FOXD3-mediated transactivation of ALKBH5 promotes neuropathic pain via m6A-dependent stabilization of 5-HT3A mRNA in sensory neurons.

The N6-methyladenosine (m6A) modification of RNA is an emerging epigenetic regulatory mechanism that has been shown to participate in various pathophysiological processes. However, its involvement in modulating neuropathic pain is still poorly understood. In this study, we elucidate a functional role of the m6A demethylase alkylation repair homolog 5 (ALKBH5) in modulating trigeminal-mediated neuropathic pain. Peripheral nerve injury selectively upregulated the expression level of ALKBH5 in the injured trigeminal ganglion (TG) of rats. Blocking this upregulation in injured TGs alleviated trigeminal neuropathic pain, while mimicking the upregulation of ALKBH5 in intact TG neurons sufficiently induced pain-related behaviors. Mechanistically, histone deacetylase 11 downregulation induced by nerve injury increases histone H3 lysine 27 acetylation (H3K27ac), facilitating the binding of the transcription factor forkhead box protein D3 (FOXD3) to the Alkbh5 promoter and promoting Alkbh5 transcription. The increased ALKBH5 erases m6A sites in Htr3a messenger RNA (mRNA), resulting in an inability of YT521-B homology domain 2 (YTHDF2) to bind to Htr3a mRNA, thus causing an increase in 5-HT3A protein expression and 5-HT3 channel currents. Conversely, blocking the increased expression of ALKBH5 in the injured TG destabilizes nerve injury-induced 5-HT3A upregulation and reverses mechanical allodynia, and the effect can be blocked by 5-HT3A knockdown. Together, FOXD3-mediated transactivation of ALKBH5 promotes neuropathic pain through m6A-dependent stabilization of Htr3a mRNA in TG neurons. This mechanistic understanding may advance the discovery of new therapeutic targets for neuropathic pain management.

The Multifaceted Functions of TRPV4 and Calcium Oscillations in Tissue Repair.

The transient receptor potential vanilloid 4 (TRPV4) specifically functions as a mechanosensitive ion channel and is responsible for conveying changes in physical stimuli such as mechanical stress, osmotic pressure, and temperature. TRPV4 enables the entry of cation ions, particularly calcium ions, into the cell. Activation of TRPV4 channels initiates calcium oscillations, which trigger intracellular signaling pathways involved in a plethora of cellular processes, including tissue repair. Widely expressed throughout the body, TRPV4 can be activated by a wide array of physicochemical stimuli, thus contributing to sensory and physiological functions in multiple organs. This review focuses on how TRPV4 senses environmental cues and thereby initiates and maintains calcium oscillations, critical for responses to organ injury, tissue repair, and fibrosis. We provide a summary of TRPV4-induced calcium oscillations in distinct organ systems, along with the upstream and downstream signaling pathways involved. In addition, we delineate current animal and disease models supporting TRPV4 research and shed light on potential therapeutic targets for modulating TRPV4-induced calcium oscillation to promote tissue repair while reducing tissue fibrosis.

Metal-Organic Frameworks and Their Composites for Chronic Wound Healing: From Bench to Bedside.

Chronic wounds are characterized by delayed and dysregulated healing processes. As such, they have emerged as an increasingly significant threat. The associated morbidity and socioeconomic toll are clinically and financially challenging, necessitating novel approaches in the management of chronic wounds. Metal-organic frameworks (MOFs) are an innovative type of porous coordination polymers, with low toxicity and high eco-friendliness. Documented anti-bacterial effects and pro-angiogenic activity predestine these nanomaterials as promising systems for the treatment of chronic wounds. In this context, the therapeutic applicability and efficacy of MOFs remain to be elucidated. It is, therefore, reviewed the structural-functional properties of MOFs and their composite materials and discusses how their multifunctionality and customizability can be leveraged as a clinical therapy for chronic wounds.

Epigenetic regulation of beta-endorphin synthesis in hypothalamic arcuate nucleus neurons modulates neuropathic pain in a rodent pain model.

Although beta-endorphinergic neurons in the hypothalamic arcuate nucleus (ARC) synthesize beta-endorphin (ß-EP) to alleviate nociceptive behaviors, the underlying regulatory mechanisms remain unknown. Here, we elucidated an epigenetic pathway driven by microRNA regulation of ß-EP synthesis in ARC neurons to control neuropathic pain. In pain-injured rats miR-203a-3p was the most highly upregulated miRNA in the ARC. A similar increase was identified in the cerebrospinal fluid of trigeminal neuralgia patients. Mechanistically, we found histone deacetylase 9 was downregulated following nerve injury, which decreased deacetylation of histone H3 lysine-18, facilitating the binding of NR4A2 transcription factor to the miR-203a-3p gene promoter, thereby upregulating miR-203a-3p expression. Further, increased miR-203a-3p was found to maintain neuropathic pain by targeting proprotein convertase 1, an endopeptidase necessary for the cleavage of proopiomelanocortin, the precursor of ß-EP. The identified mechanism may provide an avenue for the development of new therapeutic targets for neuropathic pain treatment.

CD201+ fascia progenitors choreograph injury repair.

Optimal tissue recovery and organismal survival are achieved by spatiotemporal tuning of tissue inflammation, contraction and scar formation1. Here we identify a multipotent fibroblast progenitor marked by CD201 expression in the fascia, the deepest connective tissue layer of the skin. Using skin injury models in mice, single-cell transcriptomics and genetic lineage tracing, ablation and gene deletion models, we demonstrate that CD201+ progenitors control the pace of wound healing by generating multiple specialized cell types, from proinflammatory fibroblasts to myofibroblasts, in a spatiotemporally tuned sequence. We identified retinoic acid and hypoxia signalling as the entry checkpoints into proinflammatory and myofibroblast states. Modulating CD201+ progenitor differentiation impaired the spatiotemporal appearances of fibroblasts and chronically delayed wound healing. The discovery of proinflammatory and myofibroblast progenitors and their differentiation pathways provide a new roadmap to understand and clinically treat impaired wound healing.

Adiponectin receptor 1-mediated stimulation of Cav3.2 channels in trigeminal ganglion neurons induces nociceptive behaviors in mice.

BACKGROUND: Adipokines, including adiponectin, are implicated in nociceptive pain; however, the underlying cellular and molecular mechanisms remain unknown. METHODS: Using electrophysiological recording, immunostaining, molecular biological approaches and animal behaviour tests, we elucidated a pivotal role of adiponectin in regulating membrane excitability and pain sensitivity by manipulating Cav3.2 channels in trigeminal ganglion (TG) neurons. RESULTS: Adiponectin enhanced T-type Ca2+ channel currents (IT) in TG neurons through the activation of adiponectin receptor 1 (adipoR1) but independently of heterotrimeric G protein-mediated signaling. Coimmunoprecipitation revealed a physical association between AdipoR1 and casein kinase II alpha-subunits (CK2α) in the TG, and inhibiting CK2 activity by chemical inhibitor or siRNA targeting CK2α prevented the adiponectin-induced IT response. Adiponectin significantly activated protein kinase C (PKC), and this effect was abrogated by CK2α knockdown. Adiponectin increased the membrane abundance of PKC beta1 (PKCß1). Blocking PKCß1 pharmacologically or genetically abrogated the adiponectin-induced IT increase. In heterologous expression systems, activation of adipoR1 induced a selective enhancement of Cav3.2 channel currents, dependent on PKCß1 signaling. Functionally, adiponectin increased TG neuronal excitability and induced mechanical pain hypersensitivity, both attenuated by T-type channel blockade. In a trigeminal neuralgia model induced by chronic constriction injury of infraorbital nerve, blockade of adipoR1 signaling suppressed mechanical allodynia, which was prevented by silencing Cav3.2. CONCLUSION: Our study elucidates a novel signaling cascade wherein adiponectin stimulates TG Cav3.2 channels via adipoR1 coupled to a novel CK2α-dependent PKCß1. This process induces neuronal hyperexcitability and pain hypersensitivity. Insight into adipoR-Cav3.2 signaling in sensory neurons provides attractive targets for pain treatment.

Fibroblasts - the cellular choreographers of wound healing.

Injuries to our skin trigger a cascade of spatially- and temporally-synchronized healing processes. During such endogenous wound repair, the role of fibroblasts is multifaceted, ranging from the activation and recruitment of innate immune cells through the synthesis and deposition of scar tissue to the conveyor belt-like transport of fascial connective tissue into wounds. A comprehensive understanding of fibroblast diversity and versatility in the healing machinery may help to decipher wound pathologies whilst laying the foundation for novel treatment modalities. In this review, we portray the diversity of fibroblasts and delineate their unique wound healing functions. In addition, we discuss future directions through a clinical-translational lens.

Immunomodulatory Nanosystems: Advanced Delivery Tools for Treating Chronic Wounds.

The increasingly aging society led to a rise in the prevalence of chronic wounds (CWs), posing a significant burden to public health on a global scale. One of the key features of CWs is the presence of a maladjusted immune microenvironment characterized by persistent and excessive (hyper)inflammation. A variety of immunomodulatory therapies have been proposed to address this condition. Yet, to date, current delivery systems for immunomodulatory therapy remain inadequate and lack efficiency. This highlights the need for new therapeutic delivery systems, such as nanosystems, to manage the pathological inflammatory imbalance and, ultimately, improve the treatment outcomes of CWs. While a plethora of immunomodulatory nanosystems modifying the immune microenvironment of CWs have shown promising therapeutic effects, the literature on the intersection of immunomodulatory nanosystems and CWs remains relatively scarce. Therefore, this review aims to provide a comprehensive overview of the pathogenesis and characteristics of the immune microenvironment in CWs, discuss important advancements in our understanding of CW healing, and delineate the versatility and applicability of immunomodulatory nanosystems-based therapies in the therapeutic management of CWs. In addition, we herein also shed light on the main challenges and future perspectives in this rapidly evolving research field.

Wound infiltrating adipocytes are not myofibroblasts.

The origins of wound myofibroblasts and scar tissue remains unclear, but it is assumed to involve conversion of adipocytes into myofibroblasts. Here, we directly explore the potential plasticity of adipocytes and fibroblasts after skin injury. Using genetic lineage tracing and live imaging in explants and in wounded animals, we observe that injury induces a transient migratory state in adipocytes with vastly distinct cell migration patterns and behaviours from fibroblasts. Furthermore, migratory adipocytes, do not contribute to scar formation and remain non-fibrogenic in vitro, in vivo and upon transplantation into wounds in animals. Using single-cell and bulk transcriptomics we confirm that wound adipocytes do not convert into fibrogenic myofibroblasts. In summary, the injury-induced migratory adipocytes remain lineage-restricted and do not converge or reprogram into a fibrosing phenotype. These findings broadly impact basic and translational strategies in the regenerative medicine field, including clinical interventions for wound repair, diabetes, and fibrotic pathologies.

A Survey on Label-Efficient Deep Image Segmentation: Bridging the Gap Between Weak Supervision and Dense Prediction.

The rapid development of deep learning has made a great progress in image segmentation, one of the fundamental tasks of computer vision. However, the current segmentation algorithms mostly rely on the availability of pixel-level annotations, which are often expensive, tedious, and laborious. To alleviate this burden, the past years have witnessed an increasing attention in building label-efficient, deep-learning-based image segmentation algorithms. This paper offers a comprehensive review on label-efficient image segmentation methods. To this end, we first develop a taxonomy to organize these methods according to the supervision provided by different types of weak labels (including no supervision, inexact supervision, incomplete supervision and inaccurate supervision) and supplemented by the types of segmentation problems (including semantic segmentation, instance segmentation and panoptic segmentation). Next, we summarize the existing label-efficient image segmentation methods from a unified perspective that discusses an important question: how to bridge the gap between weak supervision and dense prediction - the current methods are mostly based on heuristic priors, such as cross-pixel similarity, cross-label constraint, cross-view consistency, and cross-image relation. Finally, we share our opinions about the future research directions for label-efficient deep image segmentation.

Reactive Oxygen Species-Scavenging Nanosystems in the Treatment of Diabetic Wounds.

Diabetic wounds are characterized by drug-resistant bacterial infections, biofilm formation, impaired angiogenesis and perfusion, and oxidative damage to the microenvironment. Given their complex nature, diabetic wounds remain a major challenge in clinical practice. Reactive oxygen species (ROS), which have been shown to trigger hyperinflammation and excessive cellular apoptosis, play a pivotal role in the pathogenesis of diabetic wounds. ROS-scavenging nanosystems have recently emerged as smart and multifunctional nanomedicines with broad synergistic applicability. The documented anti-inflammatory and pro-angiogenic ability of ROS-scavenging treatments predestines these nanosystems as promising options for the treatment of diabetic wounds. Yet, in this context, the therapeutic applicability and efficacy of ROS-scavenging nanosystems remain to be elucidated. Herein, the role of ROS in diabetic wounds is deciphered, and the properties and strengths of nanosystems with ROS-scavenging capacity for the treatment of diabetic wounds are summarized. In addition, the current challenges of such nanosystems and their potential future directions are discussed through a clinical-translational lens.

Therapeutic Silencing of p120 in Fascia Fibroblasts Ameliorates Tissue Repair.

Deep skin wounds rapidly heal by mobilizing extracellular matrix and cells from the fascia, deep beneath the dermal layer of the skin, to form scars. Despite wounds being an extensively studied area and an unmet clinical need, the biochemistry driving this patch-like repair remains obscure. Lacking also are efficacious therapeutic means to modulate scar formation in vivo. In this study, we identify a central role for p120 in mediating fascia mobilization and wound repair. Injury triggers p120 expression, largely within engrailed-1 lineage-positive fibroblasts of the fascia that exhibit a supracellular organization. Using adeno-associated virus‒mediated gene silencing, we show that p120 establishes the supracellular organization of fascia engrailed-1 lineage-positive fibroblasts, without which fascia mobilization is impaired. Gene silencing of p120 in fascia fibroblasts disentangles their supracellular organization, reducing the transfer of fascial cells and extracellular matrix into wounds and augmenting wound healing. Our findings place p120 as essential for fascia mobilization, opening, to our knowledge, a previously unreported therapeutic avenue for targeted intervention in the treatment of a variety of skin scar conditions.

Diversity of Fibroblasts and Their Roles in Wound Healing.

Wound healing disorders are a societal, clinical, and healthcare burden and understanding and treating them is a major challenge. A particularly important cell type in the wound healing processes is the fibroblast. Fibroblasts are not homogenous; however, there are diverse functional fibroblast subtypes coming from different embryonic origins and residing in dispersed anatomic locations including distinct classes of fibroblasts at various skin depths. In this review, we discuss the implications of fibroblast heterogeneity, with a focus on the fundamental physiological functions of the fibroblast subtypes that govern wound repair and clinical degrees of healing. A better understanding of these diverse functional fibroblast populations will likely lead to novel therapies to enhance wound healing and inhibit excessive scarring.

Prevalence and Clinical Characteristics of Calciphylaxis in Chinese Hemodialysis Patients.

Background: Calciphylaxis is a grievous life-threatening vascular disease that commonly affects dialysis population. This is the first epidemiological survey of calciphylaxis initiated in China. Methods: In the cross-sectional survey, a stratified sampling method was used to select 24 dialysis centers in Jiangsu Province. The participants were all adult patients in each center who had been on hemodialysis for more than 6 months. Calciphylaxis patients were uniformly diagnosed based on characteristic skin lesions and histopathological features. Results: A total of 3,867 hemodialysis patients (average age of 55.33 ± 13.89 years; 61.81% of males) were included. Forty eight cases were diagnosed with calciphylaxis, and prevalence was 1.24%. Among calciphylaxis patients, 33 cases were male, and the average age and median dialysis duration were 53.85 ± 15.17 years and 84.00 (48.00, 138.75) months, respectively. Skin biopsy was performed in 70.83% of calciphylaxis patients, and positive rate was 64.71%. Meanwhile, the positive rate of bone scintigraphy in the diagnosis of calciphylaxis was 62.5%. The prevalence of hyperparathyroidism in case group was as high as 72.92% with longer duration, and 42.86% had undergone parathyroidectomy. Multivariate analysis indicated that increased BMI, prolonged dialysis duration, warfarin therapy, hyperparathyroidism, diabetes, tumors, low serum albumin and high serum alkaline phosphatase levels were high-risk factors for calciphylaxis. Conclusions: The prevalence of calciphylaxis in Chinese hemodialysis patients was 1.24% according to regional epidemiological survey, but its actual prevalence would be presumably far beyond present data. It's urgent to improve clinical understanding of calciphylaxis, and multifaceted diagnostic methods should be applied for early screening.

Genital Wound Repair and Scarring.

Skin wound repair has been the central focus of clinicians and scientists for almost a century. Insights into acute and chronic wound healing as well as scarring have influenced and ameliorated wound treatment. Our knowledge of normal skin notwithstanding, little is known of acute and chronic wound repair of genital skin. In contrast to extra-genital skin, hypertrophic scarring is uncommon in genital tissue. Chronic wound healing disorders of the genitals are mostly confined to mucosal tissue diseases. This article will provide insights into the differences between extra-genital and genital skin with regard to anatomy, physiology and aberrant wound repair. In light of fundamental differences between genital and normal skin, it is recommended that reconstructive and esthetic surgery should exclusively be performed by specialists with profound expertise in genital wound repair.

The arginine methyltransferase PRMT7 promotes extravasation of monocytes resulting in tissue injury in COPD.

Extravasation of monocytes into tissue and to the site of injury is a fundamental immunological process, which requires rapid responses via post translational modifications (PTM) of proteins. Protein arginine methyltransferase 7 (PRMT7) is an epigenetic factor that has the capacity to mono-methylate histones on arginine residues. Here we show that in chronic obstructive pulmonary disease (COPD) patients, PRMT7 expression is elevated in the lung tissue and localized to the macrophages. In mouse models of COPD, lung fibrosis and skin injury, reduced expression of PRMT7 associates with decreased recruitment of monocytes to the site of injury and hence less severe symptoms. Mechanistically, activation of NF-κB/RelA in monocytes induces PRMT7 transcription and consequential mono-methylation of histones at the regulatory elements of RAP1A, which leads to increased transcription of this gene that is responsible for adhesion and migration of monocytes. Persistent monocyte-derived macrophage accumulation leads to ALOX5 over-expression and accumulation of its metabolite LTB4, which triggers expression of ACSL4 a ferroptosis promoting gene in lung epithelial cells. Conclusively, inhibition of arginine mono-methylation might offer targeted intervention in monocyte-driven inflammatory conditions that lead to extensive tissue damage if left untreated.

Interleukin 33-mediated inhibition of A-type K+ channels induces sensory neuronal hyperexcitability and nociceptive behaviors in mice.

Background: Interleukin-33 (IL-33) has been implicated in nociceptive pain behaviors. However, the underlying molecular and cellular mechanisms remain unclear. Methods: Using electrophysiological recording, immunoblot analysis, immunofluorescence labeling, reverse transcription-PCR, siRNA-mediated knockdown approach and behavior tests, we determined the role of IL-33 in regulating sensory neuronal excitability and pain sensitivity mediated by A-type K+ channels. Results: IL-33 decreased A-type transient outward K+ currents (IA) in small-sized DRG neurons in a concentration-dependent manner, whereas the delayed rectifier currents (IDR) remained unaffected. This IL-33-induced IA decrease was dependent on suppression of the tumorigenicity 2 (ST2) receptor and was associated with a hyperpolarizing shift in the steady-state inactivation. Antagonism of Syk abrogated the IL-33-induced IA response, while inhibition of JAK2 and PKA elicited no such effect. Exposure of DRG cells to IL-33 increased the activity of Akt, but surprisingly, neither Akt nor PI3K influenced the IL-33-induced IA response. IL-33 increased the level of phosphorylated p38 mitogen-activated protein kinase (MAPK). Chemical inhibition of p38 and genetic siRNA knockdown of p38 beta (p38ß), but not p38α, abrogated the IA response induced by IL-33. Moreover, IL-33 increased neuronal excitability of DRG neurons and facilitated peripheral pain sensitivity in mice; both of these effects were occluded by IA blockade. Conclusions: Our present study reveals a novel mechanism by which IL-33/ST2 suppresses IA via a Syk-dependent p38ß signaling pathway. This mechanism thereby increases DRG neuronal excitability and pain sensitivity in mice. Targeting IL-33/ST2-mediated p38ß signaling may represent a therapeutic approach to ameliorate pain behaviors.

Histone methylation-mediated microRNA-32-5p down-regulation in sensory neurons regulates pain behaviors via targeting Cav3.2 channels.

microRNA (miRNA)­mediated gene regulation has been studied as a therapeutic approach, but its functional regulatory mechanism in neuropathic pain is not well understood. Here, we identify that miRNA-32-5p (miR-32-5p) is a functional RNA in regulating trigeminal-mediated neuropathic pain. High-throughput sequencing and qPCR analysis showed that miR-32-5p was the most down-regulated miRNA in the injured trigeminal ganglion (TG) of rats. Intra-TG injection of miR-32-5p agomir or overexpression of miR-32-5p by lentiviral delivery in neurons of the injured TG attenuated established trigeminal neuropathic pain. miR-32-5p overexpression did not affect acute physiological pain, while miR-32-5p down-regulation in intact rats was sufficient to cause pain-related behaviors. Nerve injury increased the methylated histone occupancy of binding sites for the transcription factor glucocorticoid receptor in the miR-32-5p promoter region. Inhibition of the enzymes that catalyze H3K9me2 and H3K27me3 restored the expression of miR-32-5p and markedly attenuated pain behaviors. Further, miR-32-5p­targeted Cav3.2 T-type Ca2+ channels and decreased miR-32-5p associated with neuropathic pain caused an increase in Cav3.2 protein expression and T-type channel currents. Conversely, miR-32-5p overexpression in injured TG suppressed the increased expression of Cav3.2 and reversed mechanical allodynia. Together, we conclude that histone methylation-mediated miR-32-5p down-regulation in TG neurons regulates trigeminal neuropathic pain by targeting Cav3.2 channels.

Cascade Tumor Therapy Platform for Sensitized Chemotherapy and Penetration Enhanced Photothermal Therapy.

As a stand-alone therapy strategy may not be sufficient for effective cancer treatment and a combination of chemotherapy with other therapies is a main trend in cancer treatment. A combination of chemotherapy and photothermal therapy (PTT) is reported here to achieve the goal of cascade multistage cancer treatment. A thermally responsive amphiphilic copolymer is designed and then a CuS nanoparticles (NPs)-based carbon monoxide (CO) photoinduced release system and doxorubicin (Dox) are encapsulated to construct the nanomedicine. The large-sized nanomedicine can accumulate in tumors after long circulation in vivo and will generate heat to act as a photothermal therapeutic agent by near infrared (NIR) light. Moreover, synergically release of CO and Dox is achieved and acted as a sensitized chemotherapeutic agent. The combination of PTT and chemotherapy sensitization can effectively eliminate active tumor cells in the periphery of the tumor. CuS NPs are also released after the degradation of nanomedicine and small-sized CuS NPs possess better tumor penetration and achieve penetration-enhanced PTT by further NIR irradiation, thereby effectively eliminating tumor cells inside solid tumors. Hence, cascade multistage cancer treatment of "combined PTT and chemotherapy sensitization"-"penetration-enhanced PTT" is achieved, and tumor cells are comprehensively and effectively eliminated.