This study aims to investigate the role of IL-17 in fluoxetine resistance in depression.

The Weighted Gene Coexpression Network Analysis (WGCNA) was utilized to analyze differentially expressed genes between response to antidepressant (GRA) group and the resistance to antidepressant (AR) group. Furthermore, a treatment resistance model of depression was established in Chronic unpredictable mild stress (CUMS) mice administrated with fluoxetine (widely used clinical medication for the treatment of depression) according to sucrose preference rate. Depression-like behaviors in mice were detected in Control group, CUMS group, GRA group, AR group, and SR1001 (Th17 differentiation inhibitor) group. Subsequently, HT22 cells were exposed to IL-17 secreted by Th17 differentiation. Transcriptome sequencing from the Control and IL-17 group was used to screen differential genes. HT22 cells were then transfected with si-JAK1 or si-STAT6. Th17 differentiation, the integrity of the blood-brain barrier (BBB), JAK1-STAT6 signaling pathway related proteins were detected by western blot, immunocytochemistry, flow cytometric analysis, ELISA experiments, immunofluorescence, and PCR.

The WGCNA showed that Th17 differentiation played an important role in the treatment resistance of depression. The results of the following animal experiments showed that fluoxetine resistance resulted in a reduction in total distance and average speed in the Open Field Test (OFT), an increase in immobility time during the Forced Swim Test (FST) and Tail Suspension Test (TST). It also regulated the expression of the SERT protein, Th17 differentiation, IL-17 secretion, and compromised the integrity of BBB, yielding similar outcomes in CUMS mice. However, these results could be reversed by SR1001. Moreover, IL-17 effectively elevated the SERT protein level and activated the JAK1-STAT6 signaling pathway in vivo and in vitro.

The inhibition of Th17 differentiation and the reduction of peripheral IL-17 release could decrease sensitivity to fluoxetine resistance and relieve the depression-like behavior. This process might be associated with the JAK1-STAT6 pathway.

Psoriasis is a chronic inflammatory skin autoimmune disease. Th17 cells, when pathologically activated, significantly contribute to the progression of psoriasis. The symptoms of this skin condition could be notably alleviated by targeting and suppressing the activity of these cells. Retinoic acid receptor-associated orphan nuclear hormone receptor γ-t (RORγt), a critical transcription factor in Th17 cells, emerges as a promising therapeutic target for autoimmune conditions which are mediated by the dysregulation of these cells. In this study, we designed and synthesised a series of artemisinin analogues based on the chemical structure of artemisinin, and screened 3 compounds, QHS-1, QHS-2, and QHS-3, with better inhibition efficiency of RORγt activity. We found that each of the three artemisinin analogues were demonstrated efficacy in curbing IMQ-induced skin inflammation and the abnormal proliferation of keratinocytes within the BALB/c mouse model of psoriasis. Our findings indicate that the three artemisinin analogues not only effectively mitigated skin inflammation and the abnormal proliferation of keratinocytes in the IMQ-induced psoriasis model of BALB/c mice but also curtailed the infiltration of immune cells and the production of pro-inflammatory cytokines in the dermis. Furthermore, these compounds modulated the cytokine expression profiles within Th17 cells. They exerted a suppressive effect on the activity of Th17 cells by targeting RORγt, thereby dampening the inflammatory response in the dorsal skin of the mice. This inhibition led to a reduction in the pathological proliferation of keratinocytes. In conclusion, our research underscores the promising therapeutic potential of artemisinin analogues in the treatment of psoriasis, offering a slate of candidate compounds which could pave the way for novel drug development in this field.

The retinoic acid-related orphan receptor gamma (RORγt) acts as the major transcriptional activator in Th17 cell development and function to mediate adaptive immune defenses against pathogenic infection. RORγt engages accessible DNA response elements in the genome and interplays with coactivator proteins and accessory transcription factors to drive gene expression. However, how the chromatin environment mediates RORγt structure, dynamics, and function remains unclear. Here, we profile how the nucleosome promotes or restricts access to the main RORγt DNA response elements found in native enhancers and promoters, revealing preferential binding in regions of free DNA and nucleosomal entry/exit sites, with single base-pair resolution. Solution phase measurements using hydrogen deuterium exchange coupled to mass spectrometry identify novel allosteric effects that influence RORγt binding and mediate chromatin dynamics. A high-resolution structure of RORγt bound to the nucleosome reveals how structured elements assemble to confer binding specificity and avidity to chromatin substrates. The observations suggest an activation model where RORγt binding to chromatinized DNA promotes coregulator recruitment and chromatin decompaction.

Similarly to conventional steroids, bile acids function as signaling molecules, acting on a family of membrane and nuclear receptors. The best-characterized bile acid-regulated receptors are the farnesoid X receptor, activated by primary bile acids, and the G-protein-coupled bile acid receptor 1 (also known as Takeda G protein-coupled receptor 5), which is activated by secondary bile acids, such as lithocholic acid (LCA) and deoxycholic acid. Both the farnesoid X receptor and G-protein-coupled bile acid receptor 1 are expressed in cells of innate immunity, monocytes/macrophages, and natural killer cells. Their activation in these cells provides counter-regulatory signals that are inhibitory in nature and attenuate inflammation. In recent years, however, it has been increasingly appreciated that bile acids biotransformations by intestinal microbiota result in the formation of chemically different secondary bile acids that potently regulate adaptive immunity. The 3-oxoLCA and isoalloLCA, two LCA derivatives, bind receptors such as the retinoic acid receptor-related orphan receptor gamma t (RORγt) and the vitamin D receptor (VDR) that are expressed only by lymphoid cells, extending the regulatory role of bile acids to T cells, including T-helper 17 cells and type 3 innate lymphoid cells (ILC3). In this novel conceptual framework, bile acids have emerged as one of the main components of the postbiota, the waste array of chemical mediators generated by the intestinal microbiota. Deciphering the interaction of these mediators with the immune system in the intestine and liver is a novel and fascinating area of bile acid renaissance.

Circadian rhythm plays a critical role in the progression of autoimmune diseases. While our previous study demonstrated the therapeutic effects of melatonin in experimental autoimmune uveitis, the involvement of circadian rhythm remained unclear. Using a light-induced circadian rhythm disruption model, we showed that disrupted circadian rhythms exacerbate autoimmune uveitis by impairing the stability and function of Treg cells. Mechanistically, we identified the core clock gene Per1, which is significantly reduced under circadian disruption, is essential for Treg cell metabolism and immunoregulatory function. This study underscores the pivotal role of circadian rhythm-related Treg cells in autoimmune disease progression.

In the era of precision medicine, mounting evidence suggests that the time of therapy administration, or chronotherapy, has a great impact on treatment outcomes. Chronotherapy involves planning treatment timing by considering circadian rhythms, which are 24 h oscillations in behavior and physiology driven by synchronized molecular clocks throughout the body. The value of chronotherapy in cancer treatment is currently under investigation, notably in the effects of treatment timing on efficacy and side effects. Immune checkpoint inhibitor (ICI) therapy is a promising cancer treatment. However, many patients still experience disease progression or need to stop the therapy early due to side effects. There is accumulating evidence that the time of day at which ICI therapy is administered can have a substantial effect on ICI efficacy. Thus, it is important to investigate the intersections of circadian rhythms, chronotherapy, and ICI efficacy. In this review, we provide a brief overview of circadian rhythms in the context of immunity and cancer. Additionally, we outline current applications of chronotherapy for cancer treatment. We synthesize the 29 studies conducted to date that examine the impact of time-of-day administration on the efficacy of ICI therapy, its associated side effects, and sex differences in both efficacy and side effects. We also discuss potential mechanisms underlying these observed results. Finally, we highlight the challenges in this area and future directions for research, including the potential for a chronotherapeutic personalized medicine approach that tailors the time of ICI administration to individual patients' circadian rhythms.

The abundance and behaviour of all hematopoietic components display daily oscillations, supporting the involvement of circadian clock mechanisms. The daily variations of immune cell functions, such as trafficking between blood and tissues, differentiation, proliferation, and effector capabilities are regulated by complex intrinsic (cell-based) and extrinsic (neuro-hormonal, organism-based) mechanisms. While the role of the transcriptional/translational molecular machinery, driven by a set of well-conserved genes (Clock genes), in nucleated immune cells is increasingly recognized and understood, the presence of non-transcriptional mechanisms remains almost entirely unexplored. Studies on anucleate hematopoietic components, such as red blood cells and platelets, have shown that auto-sustained redox reaction cycles persist and operate in mammals. This opens to the possibility that transcriptional and non-transcriptional circadian mechanisms might coexist in nucleated immune cell populations, potentially complementing each other. It is becoming increasingly clear that disruption of the circadian rhythm at the central level (core clock) is strongly implicated in a plethora of diseases that are associated with maladaptive immune responses. On the other hand, several evidence imply that dysregulated immune activity (e.g. excessive inflammation) may alter/disrupt the proper functioning of peripheral clocks. This knowledge paves the way to the exploitation of chronobiological concepts in clinical practice. A better comprehension of various transcriptional/translational and biochemical mechanisms that maintain rhythmicity in immune system activities, as well as the many factors (host-derived, microbiota-derived, environment) that can alter or disrupt these processes, will facilitate the development of novel chrono-immunotherapeutic approaches.

The term "circadian rhythm" refers to the 24-h oscillations found in various physiological processes in organisms, responsible for maintaining bodily homeostasis. Many neurological diseases mainly involve the process of demyelination, and remyelination is crucial for the treatment of neurological diseases. Current research mainly focuses on the key role of circadian clocks in the pathophysiological mechanisms of multiple sclerosis. Various studies have shown that the circadian rhythm regulates various cellular molecular mechanisms and signaling pathways involved in remyelination. The process of remyelination is primarily mediated by oligodendrocyte precursor cells (OPCs), oligodendrocytes, microglia, and astrocytes. OPCs are activated, proliferate, migrate, and ultimately differentiate into oligodendrocytes after demyelination, involving many key signaling pathway and regulatory factors. Activated microglia secretes important cytokines and chemokines, promoting OPC proliferation and differentiation, and phagocytoses myelin debris that inhibits remyelination. Astrocytes play a crucial role in supporting remyelination by secreting signals that promote remyelination or facilitate the phagocytosis of myelin debris by microglia. Additionally, cell-to-cell communication via gap junctions allows for intimate contact between astrocytes and oligodendrocytes, providing metabolic support for oligodendrocytes. Therefore, gaining a deeper understanding of the mechanisms and molecular pathways of the circadian rhythm at various stages of remyelination can help elucidate the fundamental characteristics of remyelination and provide insights into treating demyelinating disorders.

Diabetic cardiomyopathy, characterized by myocardial fibrosis, is a common complication of diabetes. Retinoic acid-related orphan receptor α (RORα) participates in various pathological and physiological cardiovascular processes. The current research aims to elucidate the roles and mechanisms of RORα in high glucose induced cardiac fibroblasts proliferation. Primary neonatal cardiac fibroblasts were isolated from Sprague-Dawley rats, and pre-administrated with RORα antagonist SR3335 (20 µM) or RORα agonist SR1078 (10 µM) followed by the stimulation with normal glucose (5.5 mM) or high glucose (33.3 mM) respectively. Lactate Dehydrogenase (LDH) release into culture medium, cellular adenosine-triphosphate (ATP), and cell number were detected. Expressions of Collagen I, Collagen III, proliferating cell nuclear antigen (PCNA), α-smooth muscle actin (α-SMA), receptor-interacting protein kinase 1 (RIPK1) and receptor-interacting protein kinase 3 (RIPK3) were evaluated. The extent of oxidative stress was also assessed. Our study found that high glucose elevated LDH release, reduced cellular ATP production, increased cells numbers, elevated expression of Collagen I, Collagen III, PCNA, α-SMA, RIPK1 and RIPK3, decreased mitochondrial membrane potential, strengthened intensity of dihydroethidium (DHE) and MitoSOX fluorescence. Above effects were all further exacerbated by SR3335 but significantly reversed by SR1078. In conclusion, RORα antagonist SR3335 promoted cell injury and proliferation, enhanced collagen synthesis, facilitated oxidative stress and necroptosis in cardiac fibroblasts with high glucose stimulation, whereas RORα agonist SR1078 showed opposing effects. Our study proposed RORα as a novel target against high glucose-induced cardiac fibroblasts proliferation, which is beneficial to clarify ideal therapeutic implication for diabetic cardiomyopathy.

AT7519, which inhibits multiple cyclin-dependent kinases, has been extensively investigated in various types of cancer cells. Previous studies have demonstrated the ability of this molecule to suppress the expression of the nuclear receptor retinoic acid-related orphan receptor gamma (RORγ) and several genes involved in hepatocellular carcinoma progression. In this study, we identified a distinct agonistic effect of AT7519 on RORγt, an isoform expressed by various immune cells, including T helper 17 lymphocytes. These immune cells play pivotal roles in shaping the tumor microenvironment and promoting the anticancer response of the immune system. After exposure to AT7519 during differentiation, primary human CD4+ T cells presented increased expression of IL17A/F, IFNG and GZMB and decreased expression of PDCD1 and CTLA4. These findings elucidate a previously unrecognized facet of AT7519 activity and suggest the potential incorporation of this molecule into immune therapies to augment the effectiveness of diverse anticancer strategies involving anti-programmed cell death protein 1 (anti-PD-1) and anti-cytotoxic T-lymphocyte antigen 4 (anti-CTLA4) regimens.

Obesity is a growing healthcare problem globally. In Saudi Arabia, 24% of adults aged 15 years and above have been living with Obesity. It is considered a chronic inflammatory condition that is linked to a wide range of disorders including type 2 diabetes mellitus, insulin resistance and cardiovascular diseases. In this study, we aimed to assess the influence of obesity on the proportion of Th17 cells among healthy, overweight, and obese women in Saudi Arabia. Additionally, we aimed to explore potential ligands targeting the master transcription factor of Th17 cells: RORγt. A cross-sectional study was conducted, wherein their body mass index (BMI) and waist circumference (WC) were measured. The proportion of peripheral Th17 cells was determined using flow cytometry. We found a decrease in the proportion of peripheral Th17 among women with central obesity, though this was observed among overweight and obese participants. Interestingly, both BMI and WC were inversely correlated with the proportion of peripheral Th17 cells in women experiencing overweight or obesity, while no change was observed among healthy participants. Notably, the analysis revealed a significant moderate negative correlation between the proportion of Th17 cells and HbA1c levels, observed only among the overweight and obese participants. In this study, we identified three potential binding sites on RORγt molecules of Th17 cells, bound to 58 chemical ligands. The majority of the chemical structures (72.4%) were targeted binding pocket 1 of the RORγt molecule. These findings could provide a new insight to develop new pharmaceutical molecules targeting immune cells to combat obesity and related metabolic disorders.

Multiple sclerosis (MS) is a complex neurodegenerative disease characterized by inflammation, demyelination, and neurodegeneration. Significant hypoxia exists in brain of people with MS (pwMS), likely contributing to inflammatory, neurodegenerative, and vascular impairments. In this review, we explore the concept of a negative feedback loop between hypoxia and inflammation, discussing its potential role in disease progression based on evidence of hypoxia, and its implications for therapeutic targets.

In the experimental autoimmune encephalomyelitis (EAE) model, hypoxia has been detected in gray matter (GM) using histological stains, susceptibility MRI and implanted oxygen sensitive probes. In pwMS, hypoxia has been quantified using near-infrared spectroscopy (NIRS) to measure cortical tissue oxygen saturation (StO2), as well as through blood-based biomarkers such as Glucose Transporter-1 (GLUT-1). We outline the potential for the hypoxia-inflammation cycle to drive tissue damage even in the absence of plaques. Inflammation can drive hypoxia through blood-brain barrier (BBB) disruption and edema, mitochondrial dysfunction, oxidative stress, vessel blockage and vascular abnormalities. The hypoxia can, in turn, drive more inflammation.

The hypoxia-inflammation cycle could exacerbate neuroinflammation and disease progression. We explore therapeutic approaches that target this cycle, providing information about potential treatments in MS. There are many therapeutic approaches that could block this cycle, including inhibiting hypoxia-inducible factor 1-α (HIF-1α), blocking cell adhesion or using vasodilators or oxygen, which could reduce either inflammation or hypoxia. This review highlights the potential significance of the hypoxia-inflammation pathway in MS and suggests strategies to break the cycle. Such treatments could improve quality of life or reduce rates of progression.

Retinoic acid-related orphan receptors (RORs) serve as transcription factors that play a pivotal role in a myriad of physiological processes within the body. Their involvement extends to critical biological processes that confer protective effects in the heart, immune system, and nervous system, as well as contributing to the mitigation of several aggressive cancer types. These protective functions are attributed to ROR's regulation of key proteins and the management of various cellular processes, including autophagy, mitophagy, inflammation, oxidative stress, and glucose metabolism, highlighting the emerging need for pharmacological approaches to modulate ROR expression. Thus, the modulation of RORs is a rapidly growing area of research aimed not only at comprehending these receptors, but also at manipulating them to attain the desired physiological response. Despite the presence of natural ROR ligands, the development of synthetic agonists with high selectivity for these receptors holds substantial therapeutic potential. The exploration and advancement of such compounds can effectively target diseases associated with ROR dysregulation, thereby providing avenues for therapeutic interventions. Herein, we provide a comprehensive examination of the multifaceted role of ROR in diverse physiological and pathophysiological conditions, accompanied by an in-depth exploration of a spectrum of ROR agonists, inverse agonists, and antagonists.

Retinoic-acid-related orphan receptors (RORs) are transcription factors belonging to the nuclear receptor subfamily consisting of RORα, RORβ, and RORγ. By binding to the ROR response elements (ROREs) on target gene promoters, RORs regulate a wide variety of cellular processes, including autophagy, mitophagy, oxidative stress, and inflammation. The regulatory roles of RORs are observed in cardiac cells, hepatocytes, pulmonary epithelial cells, renal cells, immune cells, and cancer cells. A growing body of clinical and experimental evidence suggests that ROR expression levels are markedly reduced under different pathological and stress conditions, suggesting that RORs may play a critical role in the pathogenesis of a variety of disease states, including myocardial infarction, immune disorders, cancer, and metabolic syndrome. Reductions in RORs are also associated with inhibition of autophagy, increased reactive oxygen species (ROS), and increased cell death, underscoring the importance of RORs in the regulation of these processes. Herein, we highlight the relationship between RORs and homeostatic processes that influence cell viability. Understanding how these intricate processes are governed at the cellular level is of high scientific and clinical importance to develop new therapeutic strategies that modulate ROR expression and disease progression.

Primary sclerosing cholangitis (PSC) is a rare, chronic liver disease with no approved therapies. The ursodeoxycholic acid (UDCA) has been widely used, although there is no evidence that the use of UDCA delays the time to liver transplant or increases survival. Several candidate drugs are currently being developed. The largest group of these new agents is represented by FXR agonists, including obeticholic acid, cilofexor, and tropifexor. Other agents that target bile acid metabolism are ASTB/IBAP inhibitors and fibroblasts growth factor (FGF)19 analogues. Cholangiocytes, the epithelial bile duct cells, play a role in PSC development. Recent studies have revealed that these cells undergo a downregulation of GPBAR1 (TGR5), a bile acid receptor involved in bicarbonate secretion and immune regulation. Additional agents under evaluation are PPARs (elafibranor and seladelpar), anti-itching agents such as MAS-related G-protein-coupled receptors antagonists, and anti-fibrotic and immunosuppressive agents. Drugs targeting gut bacteria and bile acid pathways are also under investigation, given the strong link between PSC and gut microbiota.

Multiple sclerosis (MS) is a common autoimmune illness that is difficult to treat. The upregulation of Th17 cells is critical in the pathological process of MS. Hederagenol (Hed) has been shown to lower IL-17 levels, although its role in MS pathophysiology is uncertain. In this study, we explore whether Hed could ameliorate MS by modulating Th17 cell differentiation, with the goal of identifying new treatment targets for MS. The experimental autoimmune encephalomyelitis (EAE) mouse model was conducted and Hed was intraperitoneally injected into mice. The weight was recorded and the clinical symptom grade was assessed. Hematoxylin-eosin staining was carried out to determine the extent of inflammation in the spinal cord and liver. The luxol Fast Blue staining was performed to detect the pathological changes in the myelin sheath. Nerve damage was detected using NeuN immunofluorescence staining and terminal deoxynucleotidyl transferase dUTP nick-end labeling staining. Immunohistology approaches were used to study alterations in immune cells in the spinal cord. The proportions of T cell subsets in the spleens were analyzed by flow cytometry. RORγt levels were measured using quantitative real-time PCR or Western blot. The activity of the RORγt promoter was analyzed by Chromatin immunoprecipitation. Hed administration reduced the clinical symptom grade of EAE mice, as well as the inflammatory infiltration, demyelination, and cell disorder of the spinal cord, while having no discernible effect on the mouse weight. In addition, Hed treatment significantly reduced the number of T cells, particularly Th17 cells in the spinal cord and spleen-isolated CD4+ T cells. Hed lowered the RORγt levels in spleens and CD4+ T cells and overexpression of RORγt reversed the inhibitory effect of Hed on Th17 differentiation. Hed decreased nerve injury by modulating Th17 differentiation through the RORγt promoter. Hed regulates Th17 differentiation by reducing RORγt promoter activity, which reduces nerve injury and alleviates EAE.

Among the T helper cell subsets, Th17 cells contribute to the development of various inflammatory and autoimmune diseases, including psoriasis, rheumatoid arthritis, inflammatory bowel disease, steroid-resistant asthma, and multiple sclerosis. Retinoid-related orphan receptor gamma t (RORγt), a nuclear hormone receptor, serves as a master transcription factor for Th17 cell differentiation. Recent findings have shown that modulating the metabolic pathway is critical for Th17 cell differentiation, particularly through the engagement of de novo lipid biosynthesis. Suppression of lipid biosynthesis, either through the pharmacological inhibition or gene deletion of related enzymes in CD4+ T cells, results in significant impairment of Th17 cell differentiation. Mechanistic studies indicate that metabolic fluxes through both the fatty acid and cholesterol biosynthetic pathways have a pivotal role in the regulation of RORγt activity through the generation of endogenous RORγt lipid ligands. This review discusses recent discoveries highlighting the importance of lipid metabolism in Th17 cell differentiation and function, as well as exploring specific molecular pathways involved in RORγt activation through cellular lipid metabolism. We further elaborate on a pioneering therapeutic approach to improve inflammatory and autoimmune disorders via the inhibition of RORγt.

Cardiac glycosides, derived from plants and animals, have been recognized since ancient times. These substances hinder the function of the sodium-potassium pump within eukaryotic cells. Many reports have shown that these compounds influence the activity of nuclear receptors. Thus, we assessed the effects of various cardiac glycosides at nontoxic concentrations on RORγ and RORγT. RORγT is a crucial protein involved in the differentiation of Th17 lymphocytes. Sixteen analyzed cardiac glycosides exhibited varying toxicities in HepG2 cells, all of which demonstrated agonistic effects on RORγ, as confirmed in the RORγ-HepG2 reporter cell line. The overexpression of both the RORγ and RORγT isoforms intensified the effects of these compounds. Additionally, these glycosides induced the expression of G6PC, a gene regulated by RORγ, in HepG2 cells. Subsequently, the effects of two endogenous cardiac glycosides (marinobufagenin and ouabain) and the three most potent glycosides (bufalin, oleandrin, and telecinobufagenin) were evaluated in Th17 primary lymphocytes. All of these compounds increased the expression of the IL17A, IL17F, IFNG, and CXCL10 genes, but they exhibited varying effects on GZMB and CCL20 expression. Molecular docking analysis revealed the robust binding affinity of cardiac glycosides for the ligand binding domain of the RORγ/RORγT receptors. Thus, we demonstrated that at nontoxic concentrations, cardiac glycosides have agonistic effects on RORγ/RORγT nuclear receptors, augmenting their activity. This potential can be harnessed to modulate the phenotype of IL17-expressing cells (e.g., Th17 or Tc17 lymphocytes) in adoptive therapy for combating various types of cancer.

Th17 cells mediated immune response is the basis of a variety of autoimmune diseases, including multiple sclerosis and its mouse model of immune aspects, experimental autoimmune encephalomyelitis (EAE). The gene network that drives both the development of Th17 and the expression of its effector program is dependent on the transcription factor RORγt. In this report, we showed that Peptidylprolyl Cis/Trans Isomerase, NIMA-Interacting 1 (Pin1) formed a complex with RORγt, and enhanced its transactivation activity, thus sustained the expression of the effector genes as well as RORγt in the EAE-pathogenic Th17 cells. We first found out that PIN1 was highly expressed in the samples from patients of multiple sclerosis, and the expression of Pin1 by the infiltrating lymphocytes in the central nerve system of EAE mice was elevated as well. An array of experiments with transgenic mouse models, cellular and molecular assays was included in the study to elucidate the role of Pin1 in the pathology of EAE. It turned out that Pin1 promoted the activation and maintained the effector program of EAE-pathogenic Th17 cells in the inflammation foci, but had little effect on the priming of Th17 cells in the draining lymph nodes. Mechanistically, Pin1 stabilized the phosphorylation of STAT3 induced by proinflammatory stimuli, and interacted with STAT3 in the nucleus of Th17 cells, which resulted in the increased expression of Rorc. Moreover, Pin1 formed a complex with RORγt, and enhanced the transactivation of RORγt to the +11 kb enhancer of Rorc, which enforced and maintained the expression of both Rorc and the effector program of pathogenic Th17 cells in EAE. Finally, the inhibition of Pin1, by genetic knockdown or by small molecule inhibitor, deceased the population of Th17 cells and the neuroinflammation, and alleviated the symptoms of EAE. These findings suggest that Pin1 is a potential therapeutic target for MS and other autoimmune inflammatory diseases.

Bile acids are steroids formed at the interface of host metabolism and intestinal microbiota. While primary bile acids are generated in the liver from cholesterol metabolism, secondary bile acids represent the products of microbial enzymes. Close to 100 different enzymatic modifications of bile acids structures occur in the human intestine and clinically guided metagenomic and metabolomic analyses have led to the identification of an extraordinary number of novel metabolites. These chemical mediators make an essential contribution to the composition and function of the postbiota, participating to the bidirectional communications of the intestinal microbiota with the host and contributing to the architecture of intestinal-liver and -brain and -endocrine axes. Bile acids exert their function by binding to a group of cell membrane and nuclear receptors collectively known as bile acid-regulated receptors (BARRs), expressed in monocytes, tissue-resident macrophages, CD4+ T effector cells, including Th17, T regulatory cells, dendritic cells and type 3 of intestinal lymphoid cells and NKT cells, highlighting their role in immune regulation. In this review we report on how bile acids and their metabolitesmodulate the immune system in inflammations and cancers and could be exploiting for developing novel therapeutic approaches in these disorders.

Macrophage dysfunction is a common feature of inflammatory disorders such as asthma, which is characterized by a strong circadian rhythm.

We monitored the protein expression pattern of the molecular circadian clock in human peripheral blood monocytes from healthy, allergic, and asthmatic donors during a whole day. Monocytes cultured of these donors allowed us to examine circadian protein expression in human monocyte-derived macrophages, M1- and M2- polarized macrophages. In monocytes, particularly from allergic asthmatics, the oscillating expression of circadian proteins CLOCK, BMAL, REV ERBs, and RORs was significantly altered. Similar changes in BMAL1 were observed in polarized macrophages from allergic donors and in tissue-resident macrophages from activated precision cut lung slices. We confirmed clock modulating, anti-inflammatory, and lung-protective properties of the inverse ROR agonist SR1001 by reduced secretion of macrophage inflammatory protein and increase in phagocytosis. Using a house dust mite model, we verified the therapeutic effect of SR1001 in vivo.

Overall, our data suggest an interaction between the molecular circadian clock and monocytes/macrophages effector function in inflammatory lung diseases. The use of SR1001 leads to inflammatory resolution in vitro and in vivo and represents a promising clock-based therapeutic approach for chronic pulmonary diseases such as asthma.

Circadian clock and clock-controlled output pathways exert temporal control in diverse aspects of skeletal muscle physiology, including the maintenance of muscle mass, structure, function, and metabolism. They have emerged as significant players in understanding muscle disease etiology and potential therapeutic avenues, particularly in Duchenne muscular dystrophy (DMD). This review examines the intricate interplay between circadian rhythms and muscle physiology, highlighting how disruptions of circadian regulation may contribute to muscle pathophysiology and the specific mechanisms linking circadian clock dysregulation with DMD. Moreover, we discuss recent advancements in chronobiological research that have shed light on the circadian control of muscle function and its relevance to DMD. Understanding clock output pathways involved in muscle mass and function offers novel insights into the pathogenesis of DMD and unveils promising avenues for therapeutic interventions. We further explore potential chronotherapeutic strategies targeting the circadian clock to ameliorate muscle degeneration which may inform drug development efforts for muscular dystrophy.

Steroid receptor coactivators (SRCs) are master regulators of transcription that play key roles in human physiology and pathology. SRCs are particularly important for the regulation of the immune system with major roles in lymphocyte fate determination and function, macrophage activity, regulation of nuclear factor κB (NF-κB) transcriptional activity and other immune system biology. The three members of the p160 SRC family comprise a network of immune-regulatory proteins that can function independently or act in synergy with each other, and compensate for - or moderate - the activity of other SRCs. Recent evidence indicates that the SRCs are key participants in governing numerous aspects of CD4+ T cell biology. Here we review findings that establish the SRCs as essential regulators of regulatory T cells (Tregs) and T helper 17 (Th17) cells, with a focus on their crucial roles in Treg immunity in cancer and Treg-Th17 cell phenotypic plasticity.

Immune cells are pivotal in the dynamic interplay between hypoxia and inflammation. During hypoxic conditions, HIF-1α, a crucial transcription factor, facilitates the adaptation of immune cells to the hypoxic micro-environment. This adaptation includes regulating immune cell metabolism, significantly impacting inflammation development. Strategies for anti-inflammatory and hypoxic relief have been proposed, aiming to disrupt the hypoxia-inflammation nexus. Research extensively focuses on anti-inflammatory agents and materials that target immune cells. These primarily mitigate hypoxic inflammation by encouraging M2-macrophage polarization, restraining neutrophil proliferation and infiltration, and maintaining Treg/TH17 balance. Additionally, oxygen-releasing nano-materials play a significant role. By alleviating hypoxia and clearing reactive oxygen species (ROS), these nano-materials indirectly influence immune cell functions. This paper delves into the response of immune cells under hypoxic conditions and the resultant effects on inflammation. It provides a comprehensive overview of various therapies targeting specific immune cells for anti-inflammatory purposes and explores nano-materials that either carry or generate oxygen to alleviate anoxic micro-environments.

Hepatic fibrosis is a dynamic process characterized by the net accumulation of an extracellular matrix resulting from chronic liver injury such as nonalcoholic steatohepatitis. Activation of hepatic stellate cells (HSCs) plays a role in transdifferentiation of quiescent cells into fibrogenic myofibroblasts. We aimed to examine the function of retinoic acid receptor-related orphan receptor alpha (RORα) and its novel agonistic ligand, 1-(4-benzyloxybenzyl)-3-(2-dimethylaminoethyl)-thiourea (ODH-08) against activation of HSCs using hepatic fibrosis mouse models.

Chemical synthesis, a reporter gene assay, surface plasmon resonance analysis, and a docking study were performed to evaluate ODH-08 as a ligand of RORα. In vivo experiments with mice fed a Western diet were performed to evaluate the effect of ODH-08. The human HSC line, Lx-2, and primary mouse HSCs were employed to identify the molecular mechanisms underlying the antifibrogenic effect of ODH-08.

A novel RORα-selective ligand, ODH-08, was developed based on modification of JC1-40, an analog of N-methylthiourea. Administration of ODH-08 to the Western diet-fed mice reduced hepatic collagen deposition and expression levels of fibrogenic markers such as α-smooth muscle actin and collagen type I alpha 1 chain. Activation of RORα-either by transient overexpression of RORα or treatment with ODH-08-suppressed the expression of fibrogenic proteins in HSCs. The activation of RORα suppressed the activity of SMAD2 and 3, which are the primary downstream proteins of transforming growth factor β.

RORα and its agonist ODH-08 have a potent antifibrotic effect, which could provide a novel antifibrotic strategy against hepatic fibrosis.

Type 1 innate lymphoid cells (ILC1s) possess adaptive immune features, which confer antigen-specific memory responses against haptens and viruses. However, the transcriptional regulation of memory ILC1 responses is currently not known. We show that retinoic acid receptor-related orphan receptor alpha (RORα) has high expression in memory ILC1s in murine contact hypersensitivity (CHS) models. RORα deficiency diminishes ILC1-mediated CHS responses significantly but has no effect on memory T cell-mediated CHS responses. During sensitization, RORα promotes sensitized-ILC1 expansion by suppressing expression of cell-cycle repressors in draining lymph nodes. RORα programs gene-expression patterns related to cell survival and is required for the long-term maintenance of memory ILC1s in the liver. Our findings reveal RORα to be a key transcriptional factor for sensitized-ILC1 expansion and long-term maintenance of memory ILC1s.

Experimental autoimmune encephalitis (EAE), an animal model of multiple sclerosis (MS), provides significant insights into the mechanisms that initiate and drive autoimmunity. MS is a chronic autoimmune disease of the central nervous system, characterized by inflammatory infiltration associated with demyelination. T lymphocyte cells play a crucial role in MS, whereas natural T regulatory (nTreg) cells prevent autoimmune inflammation by suppressing lymphocyte activity. This study sought to investigate the role of PD98059, a selective MAP kinase inhibitor, in Th1, Th9, Th17, and nTreg cells using the SJL/J mouse model of EAE. Following EAE development, the mice were intraperitoneally administered PD98059 (5 mg/kg for two weeks) daily. We evaluated the effects of PD98059 on Th1 (IFN-γ and T-bet), Th9 (IL-9 and IRF4), Th17 (IL-17A and RORγT), and nTreg (FoxP3 and Helios) cells in the spleen using flow cytometry. Moreover, we explored the effects of PD98059 on the IFN-γ, T-bet, IL-9, IRF4, IL-17A, RORγT, FoxP3, and Helios mRNA and protein levels in brain tissues using qRT-PCR and Western blot analyses. PD98059 treatment significantly decreased the proportion of CD4+IFN-γ+, CD4+T-bet+, CD4+IL-9+, CD4+IRF4+, CD4+IL-17A+, CD4+RORγT+, CD4+IL-17A+, and CD4+RORγT+ cells while increasing that of CD4+FoxP3+ and CD4+Helios+ cells. In addition, PD98059 administration decreased the mRNA and protein levels of IFN-γ, T-bet, IL-9, IRF4, IL-17A, and RORγT but increased those of FoxP3 and Helios in the brain tissue of EAE mice. Our findings suggest that PD98059 corrects immune dysfunction in EAE mice, which is concurrent with the modulation of multiple signaling pathways.

Thiostrepton (TST) is a natural antibiotic with pleiotropic properties. This study aimed to elucidate the therapeutic effect of TST on experimental colitis and identify its targets. The effect of TST on colon inflammation was evaluated in a dextran sulfate sodium (DSS)-induced colitis model and a T-cell transfer colitis model. The therapeutic targets of TST were investigated by cytokine profiling, immunophenotyping and biochemical approaches. The effect of TST on the gut microbiota and its contribution to colitis were evaluated in mice with DSS-induced colitis that were subjected to gut microbiota depletion and fecal microbiota transplantation (FMT). Alterations in the gut microbiota caused by TST were determined by 16S rDNA and metagenomic sequencing. Here, we showed that TST treatment significantly ameliorated colitis in the DSS-induced and T-cell transfer models. Specifically, TST targeted the retinoic acid-related orphan nuclear receptor RORγt to reduce the production of IL-17A by γδ T cells, type 3 innate lymphoid cells (ILC3s) and Th17 cells in mice with DSS-induced colitis. Similarly, TST selectively prevented the development of Th17 cells in the T-cell transfer colitis model and the differentiation of naïve CD4+ T cells into Th17 cells in vitro. Mechanistically, TST induced the ubiquitination and degradation of RORγt by promoting the binding of Itch to RORγt. Moreover, TST also reversed dysbiosis to control colonic inflammation. Taken together, these results from our study describe the previously unexplored role of TST in alleviating colonic inflammation by reducing IL-17A production and modulating dysbiosis, suggesting that TST is a promising candidate drug for the treatment of IBD.

The NR superfamily comprises 48 transcription factors in humans that control a plethora of gene network programs involved in a wide range of physiologic processes. This review will summarize and discuss recent progress in NR biology and drug development derived from integrating various approaches, including biophysical techniques, structural studies, and translational investigation. We also highlight how defective NR signaling results in various diseases and disorders and how NRs can be targeted for therapeutic intervention via modulation via binding to synthetic lipophilic ligands. Furthermore, we also review recent studies that improved our understanding of NR structure and signaling. SIGNIFICANCE STATEMENT: Nuclear receptors (NRs) are ligand-regulated transcription factors that are critical regulators of myriad physiological processes. NRs serve as receptors for an array of drugs, and in this review, we provide an update on recent research into the roles of these drug targets.

Circadian rhythms are endogenous periodic biological processes that occur on a daily timescale. These rhythms are generated by a transcriptional/translational feedback loop that consists of the CLOCK-BMAL1 heterodimeric transcriptional activator complex and the PER1/2-CRY1/2-CK1δ/ε repressive complex. The output pathways of this molecular feedback loop generate circadian rhythmicity in various biological processes. Among these, metabolism is a primary regulatory target of the circadian clock which can also feedback to modulate clock function. This intertwined relationship between circadian rhythms and metabolism makes circadian clock components promising therapeutic targets. Despite this, pharmacological therapeutics that target the circadian clock are relatively rare. In this review, we hope to stimulate interest in chemical chronobiology by providing a comprehensive background on the molecular mechanism of mammalian circadian rhythms and their connection to metabolism, highlighting important studies in the chemical approach to circadian research, and offering our perspectives on future developments in the field.

Obesity is a known risk factor for metabolic diseases and is often associated with chronic inflammation in adipose tissue. We previously identified the polyethoxylated flavonoid Nobiletin (NOB) as a circadian clock modulator that directly binds to and activates the ROR receptors in the core oscillator, markedly improving metabolic fitness in obese mice. Here, we show that NOB enhanced the oscillation of core clock genes in differentiated 3T3-L1 adipocytes, including ROR target genes such as Bmal1, Cry1, Dec1, and Dec2. NOB inhibited lipid accumulation in 3T3-L1 and SVF cells, concomitant with the dysregulated circadian expression of adipogenic differentiation-related genes including Cebpb, Pparg, Lpl, Scd1, and Fas. Importantly, RORα/RORγ double knockdown in 3T3-L1 cells (Ror DKD) significantly attenuated the effects of NOB on circadian gene expression and lipid accumulation. Furthermore, whereas NOB upregulated the expression of IκBα, a target of RORs, to inhibit NF-κB activation and proinflammatory cytokine expression, Ror DKD cells exhibited a heightened activation of the NF-κB pathway, further indicating a requisite role of RORs for NOB efficacy in adipocytes. Together, these results highlight a significant regulatory function of the NOB-ROR axis in the circadian expression of clock and clock-controlled genes in adipocytes, thereby governing adipogenic differentiation, lipogenesis, and inflammation.

Sepsis is defined as a dysregulated host response to infection that can result in organ dysfunction and high mortality, which needs more effective treatment urgently. Pancreas is one of the most vulnerable organs in sepsis, resulting in sepsis-associated pancreatic injury, which is a fatal complication of sepsis. The aim of this study was to investigate the effect of combination of fasudil and SR1001 on sepsis-associated pancreatic injury and to explore the underlying mechanisms. The model of sepsis-associated pancreatic injury was induced by cecal ligation and puncture. Pancreatic injury was evaluated by HE staining, histopathological scores and amylase activity. The frequency of Th17 cells was analyzed by flow cytometry. Serum IL-17 level was determined by ELISA. Protein levels of RORγt, p-STAT3, GEF-H1, RhoA and ROCK1 were determined by Western blot. The apoptosis of pancreatic cells was examined by TUNEL analysis and Hoechst33342/PI staining. Compared to the sham group, the model group showed significant pathological injury including edema, hyperemia, vacuolization and necrosis. After treatment with fasudil, model mice showed an obvious reduction of Th17 cells and IL-17. SR1001 significantly reduced the expressions of GEF-H1, RhoA and ROCK1 in the model mice. The combination treatment with fasudil and SR1001 significantly inhibited the differentiation of Th17 cells, expressions of IL-17, GEF-H1, RhoA and ROCK1, which were more effective than each mono-treatment. In addition, our data revealed a remarkable decrease of apoptosis in pancreatic acinar cells culturing with fasudil or SR1001, which was further inhibited by their combination culture. Lipopolysaccharide remarkably upregulated the differentiation of Th17 cells in vitro, which could be significantly downregulated by fasudil or SR1001, and further downregulated by their combination treatment. Taken together, the combination of fasudil with SR1001 has a synergistic effect on protecting against sepsis-associated pancreatic injury in C57BL/6 mice.

In this review, we discuss a variety of immune modulating approaches that could be used to counteract tissue-damaging viral immunoinflammatory lesions which typify many chronic viral infections. We make the point that in several viral infections the lesions can be largely the result of one or more aspects of the host response mediating the cell and tissue damage rather than the virus itself being directly responsible. However, within the reactive inflammatory lesions along with the pro-inflammatory participants there are also other aspects of the host response that may be acting to constrain the activity of the damaging components and are contributing to resolution. This scenario should provide the prospect of rebalancing the contributions of different host responses and hence diminish or even fully control the virus-induced lesions. We identify several aspects of the host reactions that influence the pattern of immune responsiveness and describe approaches that have been used successfully, mainly in model systems, to modulate the activity of damaging participants and which has led to lesion control. We emphasize examples where such therapies are, or could be, translated for practical use in the clinic to control inflammatory lesions caused by viral infections.

The circadian clock is an evolutionarily conserved mechanism that exerts pervasive temporal control in stem cell behavior. This time-keeping machinery is required for orchestrating myogenic progenitor properties in regenerative myogenesis that ameliorates muscular dystrophy. Here we report a screening platform to discover circadian clock modulators that promote myogenesis and identify chlorhexidine (CHX) as a clock-activating molecule with pro-myogenic activities.

A high-throughput molecular docking pipeline was applied to identify compounds with a structural fit for a hydrophobic pocket within the key circadian transcription factor protein, Circadian Locomotor Output Cycles Kaput (CLOCK). These identified molecules were further screened for clock-modulatory activities and functional validations for pro-myogenic properties.

CHX was identified as a clock activator that promotes distinct aspects of myogenesis. CHX activated circadian clock that reduced cycling period length and augmented amplitude. This action was mediated by the targeted CLOCK structure via augmented interaction with heterodimer partner Bmal1, leading to enhanced CLOCK/Bmal1-controlled transcription with upregulation of core clock genes. Consistent with its clock-activating function, CHX displayed robust effects on stimulating myogenic differentiation in a clock-dependent manner. In addition, CHX augmented the proliferative and migratory activities of myoblasts.

Our findings demonstrate the feasibility of a screening platform to discover clock modulators with myogenic regulatory activities. Discovery of CHX as a pro-myogenic molecule could be applicable to promote regenerative capacities in ameliorating dystrophic or degenerative muscle diseases.

Cashmere is the fine bottom hair produced by the secondary hair follicles of the skin. This hair is economically important. Previous studies by our research group have shown that exogenous melatonin (MT) can regulate the periodic growth of secondary hair follicles, induce the secondary development of villi, and alter the expression of some genes related to hair follicle development. Few studies on the regulation of villus growth by MT binding receptors have been published. In this study, MT was implanted subcutaneously behind the ear of Inner Mongolia cashmere goats. RT-qPCR, in situ hybridization, Western blot analysis, immunofluorescence and RNAi techniques were used to investigate the receptors and functions of MT in regulating the development of secondary hair follicles in Inner Mongolia cashmere goats. The results showed that MT binds to the nuclear receptor RORα on dermal papilla stimulates hair follicle development and promotes villus growth. The RORα mRNA expression in the skin of Inner Mongolia cashmere goats was periodic and showed a trend of first increasing and then decreasing. The expression began to increase in February, peaked in April, and reached the lowest level in May. RORα significantly affected the mRNA expression of β-catenin gene, a key gene in hair follicle development, in the presence of MT. It will lay a solid molecular foundation for further research on the regulation mechanism between MT receptor and villus growth and development and to achieve artificial regulation of villus growth time and yield to improve the effect of villus production.

The aryl hydrocarbon receptor (AhR) regulates Th17-polarized CD4+ T cell functions, but its role in HIV-1 replication/outgrowth remains unknown. Genetic (CRISPR-Cas9) and pharmacological inhibition reveal AhR as a barrier to HIV-1 replication in T cell receptor (TCR)-activated CD4+ T cells in vitro. In single-round vesicular stomatitis virus (VSV)-G-pseudotyped HIV-1 infection, AhR blockade increases the efficacy of early/late reverse transcription and subsequently facilitated integration/translation. Moreover, AhR blockade boosts viral outgrowth in CD4+ T cells of people living with HIV-1 (PLWH) receiving antiretroviral therapy (ART). Finally, RNA sequencing reveals genes/pathways downregulated by AhR blockade in CD4+ T cells of ART-treated PLWH, including HIV-1 interactors and gut-homing molecules with AhR-responsive elements in their promoters. Among them, HIC1, a repressor of Tat-mediated HIV-1 transcription and a tissue-residency master regulator, is identified by chromatin immunoprecipitation as a direct AhR target. Thus, AhR governs a T cell transcriptional program controlling viral replication/outgrowth and tissue residency/recirculation, supporting the use of AhR inhibitors in "shock and kill" HIV-1 remission/cure strategies.

Atopic dermatitis (AD) is a chronic inflammatory skin disease featuring skin barrier dysfunction and immune dysregulation. Previously, we reported that the retinoid-related orphan nuclear receptor RORα was highly expressed in the epidermis of normal skin. We also found that it positively regulated the expression of differentiation markers and skin barrier-related genes in human keratinocytes. In contrast, epidermal RORα expression was downregulated in the skin lesions of several inflammatory skin diseases, including AD. In this study, we generated mouse strains with epidermis-specific Rora ablation to understand the roles of epidermal RORα in regulating AD pathogenesis. Although Rora deficiency did not cause overt macroscopic skin abnormalities at the steady state, it greatly amplified MC903-elicited AD-like symptoms by intensifying skin scaliness, increasing epidermal hyperproliferation and barrier impairment, and elevating dermal immune infiltrates, proinflammatory cytokines, and chemokines. Despite the normal appearance at the steady state, Rora-deficient skin showed microscopic abnormalities, including mild epidermal hyperplasia, increased TEWL, and elevated mRNA expression of Krt16, Sprr2a, and Tslp genes, indicating subclinical impairment of epidermal barrier functions. Our results substantiate the importance of epidermal RORα in partially suppressing AD development by maintaining normal keratinocyte differentiation and skin barrier function.

As a ligand-dependent transcription factor, retinoid-associated orphan receptor γt (RORγt) that controls T helper (Th) 17 cell differentiation and interleukin (IL)-17 expression plays a critical role in the progression of several inflammatory and autoimmune conditions. An emerging novel approach to the therapy of these diseases thus involves controlling the transcriptional capacity of RORγt to decrease Th17 cell development and IL-17 production. Several RORγt inhibitors including both antagonists and inverse agonists have been discovered to regulate the transcriptional activity of RORγt by binding to orthosteric- or allosteric-binding sites in the ligand-binding domain. Some of small-molecule inhibitors have entered clinical evaluations. Therefore, in current review, the role of RORγt in Th17 regulation and Th17-related inflammatory and autoimmune diseases was highlighted. Notably, the recently developed RORγt inhibitors were summarized, with an emphasis on their optimization from lead compounds, efficacy, toxicity, mechanisms of action, and clinical trials. The limitations of current development in this area were also discussed to facilitate future research.