INTRODUCTION
Diabetes mellitus (DM), a chronic metabolic disorder, is a leading cause of foot ulcers and lower limb amputations worldwide[1]. Diabetic foot ulcers (DFUs) are of particular concern, affecting approximately 15%-25% of patients with DM throughout their lifetime[2]. DFUs are characterized by ulceration-associated neuropathy and/or peripheral arterial disease resulting from multiple factors, including poor glycemic control, foot injury, infection, foot surgery, and ischemia[3]. Various factors aggravate the development of the condition, increase its recurrence rates, and present multiple challenges to its management. Moreover, the recurrence of DFUs leads to substantial physical, psychological, and financial burdens[4]. Despite advancements in treatment, including debridement, offloading, and infection control, non-healing ulcers remain a major clinical challenge[5].
PATHOPHYSIOLOGY OF DFUS
The pathophysiology of DFUs is complex and involves a combination of persistent hyperglycemia, neuropathy, impaired wound healing, and endothelial dysfunction[6]. Prolonged hyperglycemia induces systemic damage, including peripheral nerve dysfunction, which is a key contributor to DFU development[7]. Neuropathy, a major complication of DM, progressively affects sensory, motor, and autonomic nerve functions, further aggravating foot vulnerability[8]. Peripheral sensory neuropathy reduces the patient’s perception of injury, whereas autonomic and motor neuropathy contribute to structural foot deformities, abnormal foot biomechanics, and skin dryness, amplifying vulnerability to callus formation, fissures, and ulceration[9]. Additionally, motor neuropathy alters the foot muscle mechanics, resulting in structural deformities such as hammer toe and Charcot joint[10].
Peripheral arterial disease and impaired healing mechanisms worsen tissue hypoxia, oxidative stress, inflammatory responses, and endothelial tissue dysfunction, mediating insulin resistance, vasoconstriction, and inflammation[11]. These chronic conditions, including DFUs, are associated with progressive tissue loss, complex infections, and cardiovascular disease[12]. Notably, infected ulcers contribute to over 20% of lower limb amputations[13].
DFU treatment is further complicated by nutritional insufficiencies, including deficiencies in zinc and vitamins A, C, and D[14]. Although emerging evidence suggests that vitamin D supplementation may support DFU management, clinical findings remain inconsistent[15]. The socioeconomic burden of DFUs highlights the need for improved diagnostic tools and innovative treatment strategies to effectively address the interconnected pathophysiological mechanisms of the condition.
ROLE OF EPIGENETICS IN DIABETIC WOUND HEALING
Epigenetic mechanisms such as DNA methylation and RNA modifications have recently been revealed as contributors to the development of DM and its complications. Despite the extensive body of research directed toward understanding the epigenetic mechanisms of diabetic complications such as cardiovascular diseases[16], nephropathy[17] and retinopathy[18], little is known about the role of epigenetics in the pathogenesis of DFUs. During wound healing, epigenetic mechanisms, including DNA methylation, histone modifications, and chromatin remodeling, are critical for the regulation of gene expression. Epigenetic alterations affect cellular homeostasis without modulating the underlying DNA sequence, providing control over immune responses, cell proliferation, and tissue repair[19,20]. In diabetic wounds, these processes are dysregulated, causing chronic inflammation, impaired immune cell function, and delayed healing[21]. For example, aberrant DNA methylation in immune cells such as macrophages can induce a proinflammatory environment[22]. Similarly, the disruptions of histone modification and chromatin remodeling alter the expression of genes involved in inflammation and tissue repair. These epigenetic changes are driven by factors such as hyperglycemia, inflammation, and oxidative stress, which are hallmarks of DM[23].
Presently, whether these epigenetic modifications primarily initiate changes in the diabetic wound microenvironment or exacerbate preexisting pathological conditions remains unclear. Despite studies showing that DNA methylation and hydroxymethylation regulate immune cell behavior in DFUs[19,20], direct evidence linking these changes to the onset of DFUs or proving their role in sustaining an already compromised condition remains lacking. Although the chronic nature of DFUs suggests a complex interplay among sustained hyperglycemia, inflammation, oxidative stress, and epigenetic dysregulation, the precise sequence of molecular events leading to impaired wound healing remains unresolved. Further studies are needed to determine the causal relationship between epigenetic dysregulation and DFU progression.
Accordingly, we cannot exclude the possibility that certain epigenetic modulations may serve as biomarkers of exposure to diabetic pathophysiology, possessing potential diagnostic and prognostic insights into DFU risk and progression. At the same time, other epigenetic modulations may provide mechanistic insights into how DM interrupts normal wound healing processes, potentially leading to targeted therapeutic interventions. The concept of epigenetic regulation as both a contributor and a consequence of disease is well documented in other chronic conditions, particularly cancer and cardiovascular diseases, where epigenetic dysregulation has been shown to play a dual role, acting as a key initiator of pathological transformation in some cases while exacerbating disease progression in others[24,25]. Therefore, a deeper exploration of the epigenetic mechanisms in DFUs could yield novel therapeutic strategies aimed at reversing detrimental modifications and restoring cellular homeostasis in chronic wounds.
DNA methylation and the hydroxymethylation of cytosine residues are key epigenetic mechanisms that silence gene expression[26]. Abnormal DNA methylation patterns have been observed in tissue-resident immune cells of diabetic wounds. For example, increased DNA methyltransferase 1 (DNMT1) activity in diabetic macrophages promotes a proinflammatory state and suppresses angiogenesis and extracellular matrix assembly[27,28]. Conversely, the hydroxymethylation of the regulatory region of matrix metalloproteinase 9 by TET enzymes elevates the expression of this matrix-degrading enzyme and impairs keratinocyte function and wound closure[29].
Histone modifications such as methylation and acetylation are often disrupted in diabetic wounds, causing improper gene activation or silencing[30]. For instance, Jumonji domain containing-3 (a histone demethylase) and mixed-lineage leukemia protein 1 (a histone methyltransferase) are often overexpressed in diabetic wounds, promoting macrophage-mediated inflammation[31-33]. Similarly, histone acetylation, which is associated with active gene transcription, is reduced in diabetic wounds, resulting in genes involved in tissue repair being silenced. For example, the decreased acetylation of histone H3 at the extracellular superoxide dismutase [Cu-Zn] (SOD3) gene promoter impairs antioxidative defenses, thereby exacerbating oxidative stress in diabetic wounds[34]. These observations highlight how histone modifications may serve as both markers and mediators of chronic DFUs.
Chromatin remodeling and nucleosome repositioning represent other critical epigenetic mechanisms in wound healing. In diabetic wounds, chromatin remodeling is often impaired, leading to improper gene expression and dysfunctional immune responses[35]. For example, impaired keratinocyte differentiation is associated with a low activity level of BRG1 ATPase, a key component of the SWI/SNF chromatin remodeling complex[36].
In summary, the epigenetic modulation of DNA introduces a complex layer of gene expression regulation, which is essential for effective wound healing. Dysregulation of these processes, especially in DM, can significantly impair tissue repair and regeneration. Therefore, understanding these disruptions provides opportunities for the development of therapeutic strategies to correct epigenetic errors and improve clinical outcomes in patients with chronic wounds.
KEY FINDINGS: THE WTAP-DNMT1 AXIS - A NOVEL EPIGENETIC MECHANISM
Xiao et al[37] introduced the novel concept of a Wilms tumor 1-associated protein (WTAP)-DNMT1 axis as a key epigenetic mechanism in diabetic wound healing. As a crucial component of the N6-methyladenosine (m6A) methyltransferase complex, WTAP was found to be significantly upregulated in human umbilical vein endothelial cells exposed to high glucose conditions. This increase in WTAP expression was associated with the impairment of cellular processes required for effective wound healing, including endothelial cell viability and migration as well as angiogenesis. These findings suggest that WTAP plays a detrimental role in the wound-healing process under diabetic conditions.
This study further revealed that WTAP exerts its effects through an epigenetic mechanism by modulating the m6A modification of DNMT1 mRNA, thereby enhancing its expression and causing endothelial dysfunction[37]. Furthermore, WTAP knockdown resulted in a significant reduction in the m6A modification of the DNMT1 transcripts and suppressed their expression. Notably, the reversal of DNMT1 expression restored the functions of the endothelial cells, improving their viability and migration as well as angiogenesis. These findings suggest that the WTAP-mediated m6A methylation of DNMT1 mRNA plays a critical role in impairing diabetic wound healing.
Next, the WTAP-DNMT1 axis was validated in a mouse model. WTAP knockdown in diabetic mice significantly accelerated wound healing, as evidenced by progressive wound closure, enhanced re-epithelialization, and increased collagen deposition. These observations suggest that the downregulation of WTAP promotes an effective and rapid wound-healing response under diabetic conditions. This study also demonstrated that the overexpression of DNMT1 reversed the beneficial effects of WTAP knockdown, confirming DNMT1 as a key downstream effector of WTAP. These mechanistic insights emphasize the importance of the WTAP-DNMT1 axis as a major player in diabetes-related deficits in wound healing and endothelial dysfunction[37].
As suggested by the authors, targeting the WTAP-DNMT1 axis may be a potential therapeutic strategy for diabetic wound healing. Suppressing WTAP or DNMT1 might, in principle, reverse endothelial cell dysfunction, enhance angiogenesis, and ultimately improve wound repair in patients with DM. Thus, this study opens new avenues for therapeutic interventions aimed at treating chronic complications arising from impaired wound healing in DM and offers prospects for better clinical management of the disease[37].
BROADER SIGNIFICANCE OF RNA METHYLATION IN DIABETES
The discovery of the role of WTAP in diabetic wound healing underscores the broader significance of RNA methylation in metabolic diseases. M6A modifications have been implicated in various cellular processes, including glucose metabolism, inflammation, and vascular function[38]. The dysregulation of m6A-modifying enzymes such as methyltransferase-like 3 (METTL3) and fat mass and obesity-associated (FTO) has been linked to DM-associated complications. For instance, METTL3 regulates apoptosis and inflammation in endothelial cells under high-glucose conditions[39,40]. Similarly, FTO-mediated m6A demethylation influences inflammation and vascular dysfunction[41]. Taken together, these findings highlight the potential of targeting m6A-related pathways as a therapeutic strategy for DM and its complications.
THERAPEUTIC IMPLICATIONS AND FUTURE DIRECTIONS
Targeting WTAP is a promising strategy for treating endothelial dysfunction, thereby improving DFU treatment in patients with DM. Although small-molecule inhibitors or RNA-based therapies that modulate WTAP activity have emerged as a novel class of treatments, achieving their high specificity is crucial for preventing off-target effects and preserving normal cellular functions. Additionally, combination therapies with existing treatments (e.g., growth factors or angiogenesis-promoting agents) for targeting WTAP may act synergistically to further enhance DFU treatment. These approaches illustrate the potential of multifaceted interventions in dealing with the complex pathophysiology of diabetic wounds.
In this regard, RNA-based therapeutic strategies also hold great promise[42]. The precise targeting of WTAP with small interfering RNAs (siRNAs), antisense oligonucleotides (ASOs), or mRNA-based therapies can help restore endothelial function. At the post-transcriptional level, both siRNAs and ASOs can silence WTAP, thereby reducing its expression and mitigating its pathological effects on diabetic wounds. Furthermore, the introduction of modified WTAP variants or regulatory elements through mRNA can counteract the deleterious functions of WTAP while preserving its physiological roles. Moreover, recent advances in lipid nanoparticle delivery systems have enhanced the feasibility of RNA-based therapies by enabling targeted delivery to cells in the wound microenvironment.
Beyond wound healing, the interaction between WTAP and DNMT1 in other diabetic complications such as nephropathy and retinopathy require further investigation. Studying the WTAP-DNMT1 axis in this context may reveal additional therapeutic avenues and broaden the clinical relevance of these findings. However, before these discoveries can be translated into clinical applications, further validations of the safety, efficacy, and pharmacokinetics of such treatments in larger animal models and human trials are required. Additionally, high levels of WTAP can serve as a biomarker of poor wound healing, facilitating early diagnosis and personalized treatment approaches. With the increasing recognition of RNA-based therapeutics as powerful tools in precision medicine, continued research on their application in DFUs will unlock new treatment paradigms, offering more targeted and effective solutions for managing chronic wounds and other metabolic dysfunctions.
CONCLUSION
The study by Xiao et al[37] represents a significant advancement in our understanding of diabetic wound healing. The identification of WTAP as a key epigenetic regulator as well as its interaction with DNMT1 has revealed a novel pathway that mediates endothelial dysfunction under hyperglycemic conditions. These findings not only provide new insights into the molecular mechanisms of diabetic wound pathology but also offer innovative therapeutic strategies. The increasing global burden of DM has also increased the demand for effective treatment interventions for its complications. Indeed, epigenetic therapies, including WTAP inhibitors, have great potential for treating diabetic wounds and managing DM-associated complications. Further studies are necessary to validate these findings, advance the development of targeted therapies, and explore the broader implications of RNA methylation in disease progression. Bridging the gap between molecular biology and clinical innovation is essential to improve the outcomes for millions of people living with DM.
Provenance and peer review: Invited article; Externally peer reviewed.
Peer-review model: Single blind
Specialty type: Endocrinology and metabolism
Country of origin: Kuwait
Peer-review report’s classification
Scientific Quality: Grade B
Novelty: Grade B
Creativity or Innovation: Grade B
Scientific Significance: Grade B
P-Reviewer: Chen HH S-Editor: Li L L-Editor: A P-Editor: Xu ZH
