Angiotensin-converting enzyme 2 (ACE2) receptor plays a pivotal role in the infection of several coronaviruses, including SARS-CoV and SARS-CoV-2. We combined computational and experimental protein engineering approaches to develop ACE2-YHA, a soluble, high-affinity ACE2 decoy with pan-coronavirus preventive and therapeutic potential. Leveraging native human ACE2-SARS-CoV/SARS-CoV-2 receptor binding domain (RBD) complex homology models, we employed in silico site-saturation mutagenesis to predict key ACE2-RBD interacting residues. Subsequent generation of ACE2 mutants and high-throughput screening identified specific ACE2 residue substitutions that enhanced binding to both SARS-CoV and SARS-CoV-2 RBDs. The triple mutant ACE2-YHA demonstrated significantly enhanced binding affinity to SARS-CoV, SARS-CoV-2, and bat SARSr-CoVs' RBDs. It effectively neutralized SARS-CoV and numerous SARS-CoV-2 variants with picomolar IC50s in pseudotyped virus assays. Notably, ACE2-YHA displayed potent neutralization against major variants of concern, including Delta and Omicron, in human airway epithelia, positioning it as a promising universal decoy for current and future ACE2-binding coronavirus outbreaks.

Long-term immunosuppressive therapy typically increases the risk of viral infection, yet during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, inflammatory bowel disease (IBD) patients showed reduced severe coronavirus disease 2019 (COVID-19) susceptibility. This suggests potential overlapping molecular mechanisms between IBD and COVID-19 that warrant investigation.

From April 2020 to April 2022, we enrolled 363 IBD patients and 146 healthy donors. Serum samples were analyzed by enzyme-linked immunoadsorption assay to determine the presence of anti-SARS-CoV-2 antibodies and to measure concentrations of the host-soluble factors sACE2 and mannose-binding lectin (MBL), which have SARS-CoV-2 neutralizing activity. Furthermore, colonic mucosa biopsies were analyzed by real-time PCR to confirm the upregulation of MBL2 as well as to assess the expression of genes encoding SARS-CoV-2 entry molecules (ie, ACE2, TMPRSS2, TMPRSS4, ADAM17, AGTR1).

Intestinal mucosa expression of ACE2, TMPRSS2, and TMPRSS4 genes was significantly lower in IBD than in healthy individuals, regardless of the type of medication, while ADAM17 and AGT1R were similar across groups. Serum sACE2 levels changed minimally, whereas circulating MBL levels were significantly higher in CD and somewhat elevated in UC patients versus controls. Parallel trends in MBL2 gene expression were observed in IBD patients' intestinal mucosa.

Overall, our study indicates that the presence of higher basal circulating levels of MBL in CD patients and the decreased intestinal mucosa expression of the SARS-CoV-2 receptor ACE2 and the host cell priming proteases TMPRSS2 and TMPRSS4 in both CD and UC patients may reduce COVID-19 risk, underscoring the potential protective role of these biomarkers in IBD populations against SARS-CoV-2 infection.

Human blood vessel organoids (hBVOs) have emerged as a system to model human vascular development and disease. Here, we use single-cell multi-omics together with genetic and signaling pathway perturbations to reconstruct hBVO development. Mesodermal progenitors bifurcate into endothelial and mural fates in vitro, and xenografted BVOs acquire definitive arteriovenous endothelial cell specification. We infer a gene regulatory network and use single-cell genetic perturbations to identify transcription factors (TFs) and receptors involved in cell fate specification, including a role for MECOM in endothelial and mural specification. We assess the potential of BVOs to generate organotypic states, identify TFs lacking expression in hBVOs, and find that induced LEF1 overexpression increases brain vasculature specificity. Finally, we map vascular disease-associated genes to hBVO cell states and analyze an hBVO model of diabetes. Altogether, we provide a comprehensive cell state atlas of hBVO development and illuminate the power and limitation of hBVOs for translational research.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is an enveloped RNA virus that caused the Coronavirus Disease 2019 (COVID-19) pandemic. The SARS-CoV-2 Spike glycoprotein binds to angiotensin converting enzyme 2 (ACE2) on host cells to facilitate viral entry. However, the presence of SARS-CoV-2 in nearly all human organs - including those with little or no ACE2 expression - suggests the involvement of alternative receptors. Recent studies have identified several cellular proteins and molecules that influence SARS-CoV-2 entry through ACE2-dependent, ACE2-independent, or inhibitory mechanisms. In this review, we explore how these alternative receptors were identified, their expression patterns and roles in viral entry, and their impact on SARS-CoV-2 infection. Additionally, we discuss therapeutic strategies aimed at disrupting these virus-receptor interactions to mitigate COVID-19 pathogenesis.

The COVID-19 pandemic highlighted the need for new therapeutic strategies to counter emerging pathogenic viruses. Herein, we introduce a novel fusion protein platform that enables antiviral targeting of distinct viral species based on host receptor specificity. Proof-of-concept studies focused on the human coronavirus NL63, which shares specificity for the ACE2 host receptor with the pandemic SARS-CoV and SARS-CoV-2 species. This antiviral fusion protein combines IFN-β with the soluble extracellular domain of ACE2 (IFNβ-ACE2). Both domains retained predicted bioactivities in that the IFN-β domain exhibited potent antiproliferative activity and the ACE2 domain exhibited full binding to the transmembrane SARS-CoV-2 Spike protein. In virus-washed (virus-targeted) and non-washed in vitro infection systems, we showed that the pool of IFNβ-ACE2 targeted to the virion surface had superior antiviral activity against NL63 compared to soluble ACE2, IFN-β, or the unlinked combination of ACE2 and IFN-β. The pool of IFNβ-ACE2 on the virion surface exhibited robust antiviral efficacy based on the preemptive targeting of antiviral IFN-β activity to the proximal site of viral infection. In conclusion, virus-targeted IFN-β places interferon optimally and antecedent to viral infection to constitute a new antiviral strategy.

The microvasculature, a complex network of small blood vessels, connects systemic circulation with local tissues, facilitating the nutrient and oxygen exchange that is critical for homeostasis and organ function. Engineering these structures is paramount for advancing tissue regeneration, disease modeling, and drug testing. However, replicating the intricate architecture of native vascular systems-characterized by diverse vessel diameters, cellular constituents, and dynamic perfusion capabilities-presents significant challenges. This complexity is compounded by the need to precisely integrate biomechanical, biochemical, and cellular cues. Recent breakthroughs in microfabrication, organoids, bioprinting, organ-on-a-chip platforms, and in vivo vascularization techniques have propelled the field toward faithfully replicating vascular complexity. These innovations not only enhance our understanding of vascular biology but also enable the generation of functional, perfusable tissue constructs. Here, we explore state-of-the-art technologies and strategies in microvascular engineering, emphasizing key advancements and addressing the remaining challenges to developing fully functional vascularized tissues.

Direct SARS-CoV-2 infection of endothelial cells is challenging to study in vitro. To examine whether endothelial cell culture conditions impact the ability of SARS-CoV-2 to infect cells, we evaluated the effects of commercial cell culture media composition on SARS-CoV-2 Spike-directed viral infection. In African Green Monkey kidney epithelial cells (VeroE6), we found that commercial cell culture media (EGM2) produced inhibitory effects on recombinant vesicular stomatitis virus (rVSV-SARS-CoV-2) growth that is not seen in Dulbecco's Modified Eagle Medium (DMEM). We identified Lonza's GA-1000 supplement as a potential SARS-CoV-2 inhibitor. We then compared how titrations of GA-1000 influenced rVSV-SARS-CoV-2 and SARS-CoV-2 infection. The determined IC50 of GA-1000 is observed at a 1:450 dilution, about 2-fold higher concentration than the typical cell culture concentration, against rVSV-SARS-CoV-2. In contrast, the inhibition against SARS-CoV-2 infection is modest. This work highlights the importance of cell culture medium selection for in vitro models of infections and demonstrates a method to characterize and ameliorate media formulations for infection studies.

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19) can damage the endothelium and increase arterial stiffness, potentially leading to adverse cardiovascular events. In parallel, systemic inflammation in COVID-19 also impacts endothelial function. Angiotensin-converting enzyme 2 (ACE2) promotes vasodilation and anti-inflammatory effects, but also facilitates SARS-CoV-2 entry into human cells. Thus, concerns have been raised about the use of RAAS inhibitors (RAASi) in COVID-19 patients due to potential ACE2 upregulation. However, the clinical significance of increased plasma ACE2 (sACE2) in RAASi-treated COVID-19 patients remains unclear. Methods: This prospective, single-centre study evaluated RAASi, sACE2, and vascular function in acutely ill patients with COVID-19 in comparison with acutely ill patients without COVID-19. Adult emergency department patients with confirmed or suspected COVID-19 were enrolled and underwent pulse wave velocity, ankle brachial index, and sACE2 measurements. Results: In the 152 included patients (50% female, median age 62 years, 68% COVID-19 positive), the sACE2 values were slightly higher in the COVID-19 (0.485 [0.364-1.329]) than in the non-COVID-19 subgroup (0.458 [0.356-1.138]; p = 0.70). No significant differences in sACE2 were observed between patients with and without RAASi, regardless of COVID-19 status. Pulse wave velocity values differed significantly between groups (p = 0.015). Conclusions: In emergency department patients, sACE2 was upregulated in COVID-19 patients, probably due to oxidative stress and inflammation. RAASi did not increase sACE2, but may have protective effects against inflammation. Elevated sACE2 appeared to have a beneficial effect on arterial stiffness in all patients. These findings support continued RAASi therapy in COVID-19 patients to protect against chronic inflammation and apoptosis.

Even though in mid-2023 the World Health Organization declared the end of the public health emergency of international concern status for COVID-19, many areas of uncertainty about SARS-CoV-2 infection pathophysiology remain. Although in the last 4 years pharmaceutical industries widely invested in the development of effective antiviral treatments and vaccines, large disparities in their availability worldwide still exist, thus fostering the investigation of nutritional supplements as adjuvant therapeutic approaches for disease management, especially in resource-limited settings. During the COVID-19 pandemic, vitamin D has been widely used as an over-the-counter solution to improve disease evolution, thanks to its known immunomodulatory and anti-inflammatory actions. Ecological and observational studies support a relationship between hypovitaminosis D and COVID-19 negative outcomes and, according to this evidence, several research groups investigated the role of vitamin D supplementation in protecting from SARS-CoV-2 infection and/or improving disease evolution. This narrative review is intended to offer insights into the existing data on vitamin D's biological effects in respiratory infections, especially in COVID-19. Furthermore, it will also offer a brief overview of the complex interplay between vitamin D and vaccine-elicited immune response, with special attention to anti-COVID-19 vaccines.

Background/Objectives: The SARS-CoV-2's high mutations and replication rates contribute to its high infectivity and resistance to current vaccinations and treatments. The primary cause of resistance to most current treatments aligns within the coding regions for the spike S protein of SARS-CoV-2 that has mutated. As a potential novel immunotherapy, we generated a novel fusion protein composed of a soluble ACE2 (sACE2) linked to llama-derived anti-CD16 that targets different variants of spike proteins and enhances natural killer cells to target infected cells. Methods: Here, we generated a novel sACE2-AntiCD16VHH fusion protein using a Gly4Ser linker, synthesized and cloned into the pLVX-EF1alpha-IRES-Puro vector, and further expressed in ExpiCHO-S cells and purified using Ni+NTA chromatography. Results: The fusion protein significantly blocked SARS-CoV-2 alpha, beta, delta, gamma, and omicron S-proteins binding and activating angiotensin-converting enzyme receptor-2 (ACE2) on ACE2-expressing RAW-Blue macrophage cells and the secretion of several key inflammatory cytokines, G-CSF, MIP-1A, and MCP-1, implicated in the cytokine release storm (CRS). The sACE2-Anti-CD16VHH fusion protein also bridged NK cells to ACE2-expressing human lung carcinoma A549 cells and significantly activated NK-dependent cytotoxicity. Conclusions: The findings show that a VHH directed against CD16 could be an excellent candidate to be linked to soluble ACE2 to generate a bi-specific molecule (sACE2-AntiCD16VHH) suitable for bridging effector cells and infected target cells to inhibit SARS-CoV-2 variant spike proteins binding to the ACE2 receptor in the RAW-Blue cell line and pro-inflammatory cytokines and to activate natural killer cell cytotoxicity.

One of the major challenges in the way of better fabricating vascularized adipose organoids is the destructive effect of adipogenic differentiation on preformed vasculature, which probably stems from the discrepancy between thein vivophysiological microenvironment and thein vitroculture conditions. As an intrinsic component of adipose tissue (AT), adipose tissue-derived extracellular vesicles (AT-EVs) have demonstrated both adipogenic and angiogenic ability in recent studies. However, whether AT-EVs could be employed to coordinate the angiogenesis and adipogenesis in the vascularization of adipose organoids remains largely unexplored. Herein, we present an efficient method for isolating higher-purity AT-EV preparations from lipoaspirates, and verify the superiority of AT-EV preparations' angiogenic and adipogenic capabilities over those from unpurified lipoaspirates. Next, in the spheroid culture model, it was discovered that the addition of AT-EVs could effectively improve the aggregation through enhancing intercellular adhesion of monoculture spheroids composed of human umbilical vascular endothelial cells (HUVECs), and helped produce vascularized adipose organoids with proper lipolysis and glucose uptake ability in the coculture spheroids comprised of adipose-derived stem cells (ADSCs) and HUVECs. Subsequently, it was observed that AT-EVs could exert a retaining effect on the vasculature of prevascularized coculture spheroids cultured in an adipogenic environment, compared to the reduced vascular networks where AT-EVs were absent. Altogether, these results indicate that AT-EVs, by means of releasing bioactive molecules that emulate thein vivomicroenvironment, can modify non-replicativein vitromicroenvironments, coordinatein vitroadipogenesis and angiogenesis, and facilitate the fabrication of vascularized adipose organoids.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) enters host cells via the angiotensin-converting enzyme 2 (ACE2) receptor. Mounting evidence has indicated the presence of hepatic SARS-CoV-2 infection and liver injury in patients with coronavirus disease 2019 (COVID-19). Understanding the mechanisms of hepatic SARS-CoV-2 infection is crucial for addressing COVID-19-related liver pathology and developing targeted therapies. This editorial discusses the significance of ACE2 in hepatic SARS-CoV-2 infection, drawing on the research by Jacobs et al. Their findings indicate that hepatic ACE2 expression, frequency of hepatic SARS-CoV-2 infection, and severity of liver injury are elevated in patients with pre-existing chronic liver diseases. These data suggest that hepatic ACE2 could be a promising therapeutic target for COVID-19.

The emergence of the COVID-19 pandemic made it critical to understand the immune and inflammatory responses to the SARS-CoV-2 virus. It became increasingly recognized that the immune response was a key mediator of illness severity and that its mechanisms needed to be better understood. Early infection of both tissue and immune cells, such as macrophages, leading to pyroptosis-mediated inflammasome production in an organ system critical for systemic oxygenation likely plays a central role in the morbidity wrought by SARS-CoV-2. Delayed transcription of Type I and Type III interferons by SARS-CoV-2 may lead to early disinhibition of viral replication. Cytokines such as interleukin-1 (IL-1), IL-6, IL-12, and tumor necrosis factor α (TNFα), some of which may be produced through mechanisms involving nuclear factor kappa B (NF-κB), likely contribute to the hyperinflammatory state in patients with severe COVID-19. Lymphopenia, more apparent among natural killer (NK) cells, CD8+ T-cells, and B-cells, can contribute to disease severity and may reflect direct cytopathic effects of SARS-CoV-2 or end-organ sequestration. Direct infection and immune activation of endothelial cells by SARS-CoV-2 may be a critical mechanism through which end-organ systems are impacted. In this context, endovascular neutrophil extracellular trap (NET) formation and microthrombi development can be seen in the lungs and other critical organs throughout the body, such as the heart, gut, and brain. The kidney may be among the most impacted extrapulmonary organ by SARS-CoV-2 infection owing to a high concentration of ACE2 and exposure to systemic SARS-CoV-2. In the kidney, acute tubular injury, early myofibroblast activation, and collapsing glomerulopathy in select populations likely account for COVID-19-related AKI and CKD development. The development of COVID-19-associated nephropathy (COVAN), in particular, may be mediated through IL-6 and signal transducer and activator of transcription 3 (STAT3) signaling, suggesting a direct connection between the COVID-19-related immune response and the development of chronic disease. Chronic manifestations of COVID-19 also include systemic conditions like Multisystem Inflammatory Syndrome in Children (MIS-C) and Adults (MIS-A) and post-acute sequelae of COVID-19 (PASC), which may reflect a spectrum of clinical presentations of persistent immune dysregulation. The lessons learned and those undergoing continued study likely have broad implications for understanding viral infections' immunologic and inflammatory consequences beyond coronaviruses.

ACE2 (angiotensin-converting enzyme 2) is a monocarboxypeptidase that cleaves Ang II (angiotensin II) among other substrates. ACE2 is present in the cell membrane of many organs, most abundantly in epithelial cells of kidney proximal tubules and the small intestine, and also exists in soluble forms in plasma and body fluids. Membrane-bound ACE2 exerts a renoprotective action by metabolizing Ang II and therefore attenuating the undesirable actions of excess Ang II. Therefore, soluble ACE2, by downregulating this peptide, may exert a therapeutic action. Our laboratory has designed ACE2 truncates that pass the glomerular filtration barrier to target the kidney renin-angiotensin system directly and, therefore, compensate for loss of kidney membrane-bound ACE2. Membrane-bound ACE2 is also the essential receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Soluble ACE2 proteins have been studied as a way to intercept SARS-CoV-2 from binding to membrane-bound ACE2 and prevent cell entry of SARS-CoV-2 altogether. We bioengineered a soluble ACE2 protein, termed ACE2 618-DDC-ABD, with increased binding affinity for SARS-CoV-2 and prolonged duration of action, which, when administered intranasally, provides near-complete protection from lethality in k18hACE2 mice infected with different SARS-CoV-2 variants. The main advantage of soluble ACE2 proteins for the neutralization of SARS-CoV-2 is their immediate onset of action and universality for current and future emerging SARS-CoV-2 variants. It is notable that ACE2 is critically involved in 2 dissimilar functions: as a receptor for cell entry of many coronaviruses and as an enzyme in the metabolism of Ang II, and yet in both cases, it is a therapeutic target.

Developing disease models and screening for effective drugs are key areas of modern medical research. Traditional methodologies frequently fall short in precisely replicating the intricate architecture of bodily tissues and organs. Nevertheless, recent advancements in biomaterial-assisted organoid technology have ushered in a paradigm shift in biomedical research. This innovative approach enables the cultivation of three-dimensional cellular structures in vitro that closely emulate the structural and functional attributes of organs, offering physiologically superior models compared to conventional techniques. The evolution of biomaterials plays a pivotal role in supporting the culture and development of organ tissues, thereby facilitating more accurate disease state modeling and the rigorous evaluation of drug efficacy and safety profiles. In this review, we will explore the roles that various biomaterials play in organoid development, examine the fundamental principles and advantages of utilizing these technologies in constructing disease models, and highlight recent advances and practical applications in drug screening using disease-specific organoid models. Additionally, the challenges and future directions of organoid technology are discussed. Through continued research and innovation, we aim to make remarkable strides in disease treatment and drug development, ultimately enhancing patient quality of life.

In the pharmaceutical research of viral respiratory infections, cell culture models have traditionally been used to evaluate the therapeutic effects of candidate compounds. Although cell lines are easy to handle and cost-effective, they do not fully replicate the characteristics of human respiratory organs. Recently, organoids and microphysiological systems (MPS) have been employed to overcome this limitation for in vitro testing of drugs against viral respiratory infections. Advanced disease modeling using organoids, self-organized three-dimensional (3D) cell culture models derived from stem cells, or MPS, models for culturing multiple cell types in a microfluidic device and capable of recapitulating a physiological 3D dynamic environment, can accurately replicate the complex functions of respiratory organs, thus making them valuable tools for elucidating the organ damages caused by viral respiratory infections and evaluating the efficacy of candidate drugs against them. Recently, a wide range of organoids and MPS have been developed to model the complex pathophysiology caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and assess therapeutic drugs. In this review, we evaluate the latest pharmaceutical research on coronavirus disease 2019 (COVID-19) that utilizes organoids and MPS and discuss future perspectives of their applications.

Recent studies have found that a link between people with type 1 diabetes mellitus (T1DM) are at higher risk of morbidity as well as mortality from COVID-19 infection, indicating a need for vaccination. T1DM appears to impair innate and adaptive immunity. The overabundance of pro-inflammatory cytokines produced in COVID-19 illness that is severe and potentially fatal is known as a "cytokine storm." Numerous cohorts have revealed chronic inflammation as a key risk factor for unfavorable COVID-19 outcomes. TNF-α, interleukin (IL)-1a, IL-1, IL-2, IL-6, and other cytokines were found in higher concentrations in patients with T1DM. Even more importantly, oxidative stress contributes significantly to the severity and course of COVID- 19's significant role in the progression and severity of COVID-19 diseases. Severe glucose excursions, a defining characteristic of type 1 diabetes, are widely recognized for their potent role as mediating agents of oxidative stress via several routes, such as heightened production of advanced glycation end products (AGEs) and activation of protein kinase C (PKC). Furthermore, persistent endothelial dysfunction and hypercoagulation found in T1DM may impair microcirculation and endothelium, which could result in the development of various organ failure and acute breathing syndrome.

Recently, angiotensin-converting enzyme 2 (ACE2) gene has emerged as a potential candidate gene for susceptibility to SARS-CoV-2 infection. We investigated whether ACE2 G8790A (rs2285666) polymorphism could be a genetic marker for susceptibility to COVID-19 and disease severity in Egyptian children and adolescents.

This was a prospective case-control study included 580 cases diagnosed with COVID-19, and 580 matched control children and adolescents. The ACE2 G8790A (rs2285666) polymorphism was genotyped using polymerase chain reaction (PCR) and ACE2 serum level was measured by ELISA.

The ACE2 A/A genotype and A-allele were significantly more represented in cases with COVID-19 as compared to control group (44% vs. 30%; OR = 2.83; [95% CI: 1.27-2.63]; p = 0.006; for the A/A genotype) and (65% vs. 51%; OR = 1.9; [95% CI: 1.06-1.72]; p = 0.01; for the A-allele). The presence of ACE2 G/G genotype was an independent risk factor for severe disease (adjusted OR: 2.08; [95% CI: 1.57-6.78]; p = 0.003).

The ACE2 G8790A (rs2285666) polymorphism may confer susceptibility to COVID-19 in Egyptian children and adolescents. The ACE2 G/G genotype and G-allele was associated with lower ACE2 serum levels and may constitute independent risk factors for disease severity.

It was in 2019 that the world experienced the devastation caused by SARS-CoV-2, contributing to a large number of deaths. This contagious virus not only challenged the health care system but has also hit the economy very badly. There has been a lot of research on effective vaccine development, and there has been some success in the same, but no effective antiviral drugs are available in the market. No doubt vaccination can prevent the disease, but it doesn't have the potential to cure an infected person, for which there is a dire need to develop some effective drug. Angiotensin convertase enzyme 2 (ACE2) played a substantial role in SARS-CoV-2 pathogenesis and thus has gained much attention during the pandemic. Moreover, it has opened up new avenues for the cure of COVID-19.

SARS-CoV-2-related proteins, ACE2 and TMPRSS2, are determinants of SARS-CoV-2 infection. Although these proteins are expressed in oral-related tissues, their expression patterns and modulatory mechanisms in the salivary glands remain unknown. We herein showed that full-length ACE2, which has both a fully functional enzyme catalytic site and high-affinity SARS-CoV-2 spike S1-binding sites, was more highly expressed in salivary glands than in oral mucosal epithelial cells and the lungs. Regarding TMPRSS2, zymogen and the cleaved form were both expressed in the salivary glands, whereas only zymogen was expressed in murine lacrimal glands and the lungs. Metformin, an AMPK activator, increased stimulated saliva secretion and full-length ACE2 expression and decreased cleaved TMPRSS2 expression in the salivary glands, and exerted the same effects on soluble ACE2 (sACE2) and sTMPRSS2 in saliva. Moreover, metformin decreased the expression of beta-galactosidase, a senescence marker, and ADAM17, a sheddase of ACE2 to sACE2, in the salivary glands. In aged mice, the expression of ACE2 was decreased in the salivary glands, whereas that of sACE2 was increased in saliva, presumably by the up-regulated expression of ADAM17. The expression of TMPRSS2 in the salivary glands and sTMPRSS2 in saliva were both increased. Collectively, these results suggest that the protein expression patterns of ACE2 and TMPRSS2 in the salivary glands differ from those in other oral-related cells and tissues, and also that metformin and aging affect the salivary expression of ACE2 and TMPRSS2, which have the potential as targets for preventing the transmission of SARS-CoV-2.

A heightened risk for thrombosis is a hallmark of COVID-19. Expansive clinical experience and medical literature have characterized small (micro) and large (macro) vessel involvement of the venous and arterial circulatory systems. Most events occur in patients with serious or critical illness in the hyperacute (first 1-2 weeks) or acute phases (2-4 weeks) of SARS-CoV-2 infection. However, thrombosis involving the venous, arterial, and microcirculatory systems has been reported in the subacute (4-8 weeks), convalescent (> 8-12 weeks) and chronic phases (> 12 weeks) among patients with mild-to-moderate illness. The purpose of the current focused review is to highlight the distinguishing clinical features, pathological components, and potential mechanisms of venous, arterial, and microvascular thrombosis in patients with COVID-19. The overarching objective is to better understand the proclivity for thrombosis, laying a solid foundation for screening and surveillance modalities, preventive strategies, and optimal patient management.

Sepsis, characterized as life-threatening organ dysfunction resulting from dysregulated host responses to infection, remains a significant challenge in clinical practice. Despite advancements in understanding host-bacterial interactions, molecular responses, and therapeutic approaches, the mortality rate associated with sepsis has consistently ranged between 10 and 16%. This elevated mortality highlights critical gaps in our comprehension of sepsis etiology. Traditionally linked to bacterial and fungal pathogens, recent outbreaks of acute viral infections, including Middle East respiratory syndrome coronavirus (MERS-CoV), influenza virus, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), among other regional epidemics, have underscored the role of viral pathogenesis in sepsis, particularly when critically ill patients exhibit classic symptoms indicative of sepsis. However, many cases of viral-induced sepsis are frequently underdiagnosed because standard evaluations typically exclude viral panels. Moreover, these viruses not only activate conventional pattern recognition receptors (PRRs) and retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs) but also initiate primary antiviral pathways such as cyclic guanosine monophosphate adenosine monophosphate (GMP-AMP) synthase (cGAS)-stimulator of interferon genes (STING) signaling and interferon response mechanisms. Such activations lead to cellular stress, metabolic disturbances, and extensive cell damage that exacerbate tissue injury while leading to a spectrum of clinical manifestations. This complexity poses substantial challenges for the clinical management of affected cases. In this review, we elucidate the definition and diagnosis criteria for viral sepsis while synthesizing current knowledge regarding its etiology, epidemiology, and pathophysiology, molecular mechanisms involved therein as well as their impact on immune-mediated organ damage. Additionally, we discuss clinical considerations related to both existing therapies and advanced treatment interventions, aiming to enhance the comprehensive understanding surrounding viral sepsis.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a global pandemic and a serious impact on human life and health. The spread of this virus, coupled with the emergence of many mutants, has posed increasingly formidable challenges to the design and development of antiviral drugs. Recently, it has been discovered that dalbavancin can bind to angiotensin-converting enzyme 2 (ACE2) of host cells with high affinity, blocking the interaction between the spike protein and ACE2, thereby making it a potentially promising anti-SARS-CoV-2 drug. It's necessary to use molecular dynamics (MD) simulations and binding free energy calculations to explore the source of the high binding affinity of dalbavancin. Computation analysis showed that due to the large molecular structure of dalbavancin, it exhibits stronger van der Waals (vdW) interactions with ACE2, which enhances the total binding free energy. In addition, our study has identified the hot-spot residues, among which the residue Lys353 has the most significant contribution, providing one-third of the total binding free energy. The energy of Lys353 was also dominated by vdW interaction. These results and analysis may provide constructive insights and suggestions for the design and development of anti-SARS-CoV-2 drugs, thereby advancing the progress in viral treatment.

The potential of ursodeoxycholic acid (UDCA) in inhibiting angiotensin-converting enzyme 2 was demonstrated. However, conflicting evidence emerged regarding the association between UDCA and COVID-19 outcomes, prompting the need for a comprehensive investigation.

Patients diagnosed with COVID-19 infection were retrospectively analyzed and divided into two groups: the UDCA-treated group and the control group. Kaplan-Meier recovery analysis and Cox proportional hazards models were used to evaluate the recovery time and hazard ratios. Additionally, study-level pooled analyses for multiple clinical outcomes were performed.

In the 115-patient cohort, UDCA treatment was significantly associated with a reduced recovery time. The subgroup analysis suggests that the 300 mg subgroup had a significant (adjusted hazard ratio: 1.63 [95% CI, 1.01 to 2.60]) benefit with a shorter duration of fever. The results of pooled analyses also show that UDCA treatment can significantly reduce the incidence of severe/critical diseases in COVID-19 (adjusted odds ratio: 0.68 [95% CI, 0.50 to 0.94]).

UDCA treatment notably improves the recovery time following an Omicron strain infection without observed safety concerns. These promising results advocate for UDCA as a viable treatment for COVID-19, paving the way for further large-scale and prospective research to explore the full potential of UDCA.

Excessive oxidative stress is known to cause endothelial dysfunction and drive cardiovascular diseases (CVD). While telomerase reverse transcriptase (TERT) shows protective effects against oxidative stress in rodents and is associated to human flow-mediated dilation in CVD, its regulatory mechanisms in human vascular systems under pathological oxidative stress require further investigation.

Human induced pluripotent stem cells (hiPSCs) were used to create vascular organoids (VOs). These VOs and human umbilical vein endothelial cells (HUVECs) were subjected to oxidative stress through both hydrogen peroxide (H2O2) and oxidized low-density lipoprotein (oxLDL) models. The effects of TERT overexpression by inhibition of the ubiquitin protein ligase E3 component N-recognin 5 (UBR5) on reactive oxygen species (ROS)-induced vascular injury and cellular senescence were assessed using neovascular sprouting assays, senescence-associated β-galactosidase (SA-β-Gal) staining, and senescence-associated secretory phenotype (SASP) assays.

ROS significantly impaired VO development and endothelial progenitor cell (EPC) angiogenesis, evidenced by reduced neovascular sprouting and increased senescence markers, including elevated SA-β-Gal activity and SASP-related cytokine levels. Overexpression of TERT counteracted these effects, restoring VO development and EPC function. Immunoprecipitation-mass spectrometry identified UBR5 as a critical TERT regulator, facilitating its degradation. Inhibition of UBR5 stabilized TERT, improving VO angiogenic capacity, and reducing SA-β-Gal activity and SASP cytokine levels.

Inhibiting UBR5 stabilizes TERT, which preserves EPC angiogenic capacity, reduces VO impairment, and delays endothelial cell senescence under oxidative stress. These findings highlight the potential of targeting UBR5 to enhance vascular health in oxidative stress-related conditions.

The mutational drift of SARS-CoV-2 and the appearance of multiple variants, including the latest Omicron variant and its sub-lineages, has significantly reduced (and in some cases abolished) the protective efficacy of Wuhan spike-antigen-based vaccines and therapeutic antibodies. One of the most functionally constrained and thus largely invariable regions of the spike protein is the one involved in the interaction with the ACE2 receptor mediating the cellular entry of SARS-CoV-2. Engineered ACE2, both as a full-length protein or as an engineered polypeptide fragment, has been shown to be capable of preventing the host-cell binding of all viral variants and to be endowed with potent SARS-CoV-2 neutralization activity both in vitro and in vivo. Here, we report on the biochemical and antiviral properties of rationally designed ACE2 N-terminal, three-helix fragments that retain a native-like conformation. One of these fragments, designated as PRP8_3H and produced in recombinant form, bears structure-stabilizing and binding-affinity enhancing mutations in α-helix-I and in both α-helix I and II, respectively. While the native-like, unmodified three α-helices ACE2 fragment proved to be thermally unstable and without any detectable pseudovirion neutralization capacity, PRP8_3H was found to be highly thermostable and capable of binding to the SARS-CoV-2 spike receptor-binding domain with nanomolar affinity and to neutralize both Wuhan and Omicron spike-expressing pseudovirions at (sub)micromolar concentrations. PRP8_3H thus lends itself as a highly promising ACE2 decoy prototype suitable for a variety of formulations and prophylactic applications.

Organoids are three-dimensional (3D) cultures, normally derived from stem cells, that replicate the complex structure and function of human tissues. They offer a physiologically relevant model to address important questions in cancer research. The generation of patient-derived organoids (PDOs) from various human cancers allows for deeper insights into tumor heterogeneity and spatial organization. Additionally, interrogating non-tumor stromal cells increases the relevance in studying the tumor microenvironment, thereby enhancing the relevance of PDOs in personalized medicine. PDOs mark a significant advancement in cancer research and patient care, signifying a shift toward more innovative and patient-centric approaches. This review covers aspects of PDO cultures to address the modeling of the tumor microenvironment, including extracellular matrices, air-liquid interface and microfluidic cultures, and organ-on-chip. Specifically, the role of PDOs as preclinical models in gene editing, molecular profiling, drug testing, and biomarker discovery and their potential for guiding personalized treatment in clinical practice are discussed.

SARS-CoV-2 uses the receptor binding domain (RBD) of its spike protein to recognize and infect host cells by binding to the cell surface receptor angiotensin converting enzyme 2 (ACE2). The ACE2 receptor is composed of peptidase domain (PD), collectrin-like domain, transmembrane domain, and short cytoplasmic domain, and may exist as a dimer on cell surface. The RBD binding site is located atop of the ACE2 PD, but the involvement of other domains in virus infection is uncertain. We found that the ACE2 PD alone, whether anchored to cell membrane via a glycosylphosphatidylinositol anchor or attached to another surface protein, is fully functional as a receptor for spike-mediated cell fusion and virus infection. However, for ACE2 to function as the viral receptor, the RBD binding site must be positioned in close proximity to the cell membrane. Elevating the surface height of ACE2 using long and rigid protein spacers reduces or eliminates cell fusion and virus infection. Moreover, we found that the RBD-targeting neutralizing antibodies, nanobodies, and de novo designed miniprotein binders, when present on cell surface, also act as viral receptors, facilitating cell fusion and virus infection. Our data demonstrate that RBD binding and close membrane proximity are essential properties for a receptor to effectively mediate SARS-CoV-2 infection. Importantly, we show that soluble RBD-binders can be engineered to make cells either susceptible or resistant to virus infection, which has significant implications for antiviral therapy and various virus-mediated applications.

Myocarditis is characterized as local or diffuse inflammatory lesions in the myocardium, primarily caused by viruses and other infections. It is a common cause of sudden cardiac death and dilated cardiomyopathy. In recent years, the global prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the widespread vaccination have coincided with a notable increase in the number of reported cases of myocarditis. In light of the potential threat that myocarditis poses to global public health, numerous studies have sought to elucidate the pathogenesis of this condition. However, despite these efforts, effective treatment strategies remain elusive. To collate the current research advances in myocarditis, and thereby provide possible directions for further research, this review summarizes the mechanisms involved in viral invasion of the organism and primarily focuses on how viruses trigger excessive inflammatory responses and in result in different types of cell death. Furthermore, this article outlines existing therapeutic approaches and potential therapeutic targets for the acute phase of myocarditis. In particular, immunomodulatory treatments are emphasized and suggested as the most extensively studied and clinically promising therapeutic options.

The dysregulation of Angiotensin-converting enzyme 2 (ACE2) in central nervous system is believed associates with COVID-19 induced cognitive dysfunction. However, the detailed mechanism remains largely unknown. In this study, we performed a comprehensive system genetics analysis on hippocampal ACE2 based on BXD mice panel. Expression quantitative trait loci (eQTLs) mapping showed that Ace2 was strongly trans-regulated, and the elevation of Ace2 expression level was significantly correlated with impaired cognitive functions. Further Gene co-expression analysis showed that Ace2 may be correlated with the membrane proteins in Calcium signaling pathway. Further, qRT-PCR confirmed that SARS-CoV-2 spike S1 protein upregulated ACE2 expression together with eight membrane proteins in Calcium Signaling pathway. Moreover, such elevation can be attenuated by recombinant ACE2. Collectively, our findings revealed a potential mechanism of Ace2 in cognitive dysfunction, which could be beneficial for COVID-19-induced cognitive dysfunction prevention and potential treatment.

The 2019 widespread contagion of the human coronavirus novel type (SARS-CoV-2) led to a pandemic declaration by the World Health Organization. A daily increase in patient numbers has formed an urgent necessity to find suitable targets and treatment options for the novel coronavirus (COVID-19). Despite scientists' struggles to discover quick treatment solutions, few effective specific drugs are approved to control SARS-CoV-2 infections thoroughly. Drug repositioning or Drug repurposing and target-based approaches are promising strategies for facilitating the drug discovery process. Here, we review current in silico, in vitro, in vivo, and clinical updates regarding proposed drugs for prospective treatment options for COVID-19. Drug targets that can direct pharmaceutical sciences efforts to discover new drugs against SARS-CoV-2 are divided into two categories: Virus-based targets, for example, Spike glycoprotein and Nucleocapsid Protein, and host-based targets, for instance, inflammatory cytokines and cell receptors through which the virus infects the cell. A broad spectrum of drugs has been found to show anti-SARS-CoV-2 potential, including antiviral drugs and monoclonal antibodies, statins, anti-inflammatory agents, and herbal products.

Severe acute respiratory syndrome coronavirus (SARS-CoV-2) preferentially infects the respiratory tract; however, several studies have implicated a multi-organ involvement. Hepatic dysfunctions caused by SARS-CoV-2 infection have been increasingly recognized and described to correlate with disease severity. To elucidate molecular factors that could contribute towards hepatic infection, we concentrated on microRNAs (miRNAs), a class of small non-coding RNAs that modulate various cellular processes and which are reported to be differentially regulated during liver injury. We aimed to study the infection of primary human hepatocytes (PHH) with SARS-CoV-2 and to evaluate the potential of miRNAs for modulating viral infection.

We analysed liver autopsies from a coronavirus disease 19 (COVID-19)-positive cohort for the presence of viral RNA using Nanopore sequencing. PHH were used for the infection with SARS-CoV-2. The candidate miRNAs targeting angiotensin converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) were identified using in silico approaches. To discover the potential regulatory mechanism, transfection experiments, qRT-PCRs, western blots and luciferase reporter assays were performed.

We could detect SARS-CoV-2 RNA in COVID-19-positive liver autopsies. We show that PHH express ACE2 and TMPRSS2 and can be readily infected with SARS-CoV-2, resulting in robust replication. Transfection of selected miRNA mimics reduced SARS-CoV-2 receptor expression and SARS-CoV-2 burden in PHH. In silico and biochemical analyses supported a potential direct binding of miR-141-3p to the SARS-CoV-2 genome.

We confirm that PHH are susceptible to SARS-CoV-2 infection and demonstrate selected miRNAs targeting SARS-CoV-2 entry factors and/or the viral genome reduce viral loads. These data provide novel insights into hepatic susceptibility to SARS-CoV-2 and associated dysfunctions in COVID-19.

Organoids are self-organizing 3D cell culture models that are valuable for studying the mechanisms underlying both development and disease in multiple species, particularly, in humans. These 3D engineered tissues can mimic the structure and function of human organs in vitro. Methods to generate organoids have substantially improved to better resemble, in various ways, their in vivo counterpart. One of the major limitations in current organoid models is the lack of a functional vascular compartment. Here we discuss methodological approaches to generating perfusable blood vessel networks in organoid systems. Inclusion of perfused vascular compartments markedly enhances the physiological relevance of organoid systems and is a critical step in the establishment of next generation, higher-complexity in vitro systems for use in developmental, clinical, and drug-development settings.

The angiotensin-converting enzyme 2 (ACE2), which is expressed in cerebral vascular endothelial cells (CVECs), has been currently identified as a functional receptor for SARS-CoV-2.

We specifically induced injury to ACE2-expressing CVECs in mice and evaluated the effects of such targeted damage through magnetic resonance imaging (MRI) and cognitive behavioral tests. In parallel, we recruited a single-center cohort of COVID-19 survivors and further assessed their brain microvascular injury based on cognition and emotional scales, cranial MRI scans, and blood proteomic measurements.

Here, we show an array of pathological and behavioral alterations characteristic of cerebral small vessel disease (CSVD) in mice that targeted damage to ACE2-expressing CVECs, and COVID-19 survivors. These CSVD-like manifestations persist for at least 7 months post-recovery from COVID-19.

Our findings suggest that SARS-CoV-2 may induce cerebral small vessel damage with persistent sequelae, underscoring the imperative for heightened clinical vigilance in mitigating or treating SARS-CoV-2-mediated cerebral endothelial injury throughout infection and convalescence.

Cerebral small vessel disease-associated changes were observed after targeted damage to angiotensin-converting enzyme 2-expressing cerebral vascular endothelial cells. SARS-CoV-2 may induce cerebral small vessel damage with persistent sequelae. Clinical vigilance is needed in preventing SARS-CoV-2-induced cerebral endothelial damage during infection and recovery.