The IL-4/IL-13 axis in skin fibrosis and scarring: mechanistic concepts and therapeutic targets

Interleukin antagonists for atopic dermatitis: a new era of therapy

INTRODUCTION

Over the last decade, increasing understanding of the immunopathogenesis of atopic dermatitis (AD) enabled the recognition of multiple therapeutic targets and subsequently the development of novel, highly effective systemic treatments, including interleukin (IL)-antagonists. To date, the IL-4Ra-inhibitor dupilumab and the IL-13 inhibitor tralokinumab have gained regulatory approval in Europe for the treatment of moderate-to-severe AD, while more than 70 new therapeutics are currently in development.

AREAS COVERED

In this review, we address the role of ILs in the pathogenesis of AD and provide an overview of the novel and investigational IL-antagonists, as regards their efficacy and safety on moderate-to-severe AD.

EXPERT OPINION

Current data have established IL-4 and IL-13 inhibitors as effective and safe for the treatment of moderate-to-severe AD, as regards the rapid control of flares as well as the long-term remission of the disease. Data regarding the efficacy and safety of other IL-inhibitors, including those targeting IL-31, IL-22, IL-33, IL-36 and IL-18, are accumulating. There is still an unmet need for real-world-evidence studies and head-to-head studies for both currently available and future agents in AD treatment. Establishing predictive biomarkers of treatment response in a disorder of such considerable heterogenicity might help physicians pursue a patient-tailored therapeutic response.

Design Strategy of Microneedle Systems for Skin Wound Healing: Based on the Structure of Tips and Therapeutic Methodologies

The skin, being the largest organ of the human body, is susceptible to damage resulting in wounds that are vulnerable to pathogenic attacks and fail to provide effective protection for internal tissues. Therefore, it is crucial to expedite wound healing. In recent years, microneedles have garnered significant attention as an innovative drug delivery system owing to their noninvasive and painless administration, simplified application process, precise control over drug release, and versatile loading capabilities. Consequently, they hold immense potential for the treatment of skin wound. This review presents a comprehensive design strategy for the microneedle system in promoting skin wound healing. First, the process of skin wound healing and the characteristics of specific wounds are elucidated. The design strategies for microneedles are subsequently presented and classified based on their structural and therapeutic methodologies. Finally, a succinct recapitulation of the previously discussed points and a prospective analysis are provided.

m6A RNA methylation: The latent string-puller in fibrosis

Fibrosis is a pathological phenomenon characterized by the aberrant accumulation of extracellular matrix (ECM) in tissues. Fibrosis is a universally age-related disease involving that many organs and is the final stage of many chronic inflammatory diseases, which often threaten the patient's health. Undoubtedly, fibrosis has become a serious economic and health burden worldwide, However, the pathogenesis of fibrosis is complex. Further, the key molecules still remain to be unraveled. Hence, so far, there have been no effective treatments designed against the key targets of fibrosis. The methylation modification on the nitrogen atom at position 6 of adenine (m6A) is the most common mRNA modification in mammals. There is increasing evidence that m6A is actively involved in the pathogenesis of fibrosis. This review aims to highlight m6A-associated mechanisms and functions in several organic fibrosis, which implies that m6A is universal and critical for fibrosis and summarize the outlook of m6A in the treatment of fibrosis. This may light up the unknown aspects of this condition for researchers interested to explore fibrosis further.

Prurigo Nodularis: Pathogenesis and the Horizon of Potential Therapeutics

Chronic pruritus that lasts for over 6 weeks can present in various forms, like papules, nodules, and plaque types, with prurigo nodularis (PN) being the most prevalent. The pathogenesis of PN involves the dysregulation of immune cell-neural circuits and is associated with peripheral neuropathies, possibly due to chronic scratching. PN is a persistent and challenging condition, involving complex interactions among the skin, immune system, and nervous system. Lesional skin in PN exhibits the infiltration of diverse immune cells like T cells, eosinophils, macrophages, and mast cells, leading to the release of inflammatory cytokines and itch-inducing substances. Activated sensory nerve fibers aggravate pruritus by releasing neurotransmitters, perpetuating a vicious cycle of itching and scratching. Traditional treatments often fail, but recent advancements in understanding the inflammatory and itch transmission mechanisms of PN have paved the way for innovative therapeutic approaches, which are explored in this review.

Fibrosis-on-Chip: A Guide to Recapitulate the Essential Features of Fibrotic Disease

Fibrosis, which is primarily marked by excessive extracellular matrix (ECM) deposition, is a pathophysiological process associated with many disorders, which ultimately leads to organ dysfunction and poor patient outcomes. Despite the high prevalence of fibrosis, currently there exist few therapeutic options, and importantly, there is a paucity of in vitro models to accurately study fibrosis. This review discusses the multifaceted nature of fibrosis from the viewpoint of developing organ-on-chip (OoC) disease models, focusing on five key features: the ECM component, inflammation, mechanical cues, hypoxia, and vascularization. The potential of OoC technology is explored for better modeling these features in the context of studying fibrotic diseases and the interplay between various key features is emphasized. This paper reviews how organ-specific fibrotic diseases are modeled in OoC platforms, which elements are included in these existing models, and the avenues for novel research directions are highlighted. Finally, this review concludes with a perspective on how to address the current gap with respect to the inclusion of multiple features to yield more sophisticated and relevant models of fibrotic diseases in an OoC format.

Beyond Encapsulation: Exploring Macrophage-Fibroblast Cross Talk in Implant-Induced Fibrosis

The foreign body response (FBR) and organ fibrosis are complex biological processes involving the interaction between macrophages and fibroblasts. Understanding the molecular mechanisms underlying macrophage-fibroblast cross talk is crucial for developing strategies to mitigate implant encapsulation, a major cause of implant failure. This article reviews the current knowledge on the role of macrophages and fibroblasts in the FBR and organ fibrosis, highlighting the similarities between these processes. The FBR is characterized by the formation of a fibrotic tissue capsule around the implant, leading to functional impairment. Various factors, including material properties such as surface chemistry, stiffness, and topography, influence the degree of encapsulation. Cross talk between macrophages and fibroblasts plays a critical role in both the FBR and organ fibrosis. However, the precise molecular mechanisms remain poorly understood. Macrophages secrete a wide range of cytokines that modulate fibroblast behavior such as abundant collagen deposition and myofibroblast differentiation. However, the heterogeneity of macrophages and fibroblasts and their dynamic behavior in different tissue environments add complexity to this cross talk. Experimental evidence from in vitro studies demonstrates the impact of material properties on macrophage cytokine secretion and fibroblast physiology. However, the correlation between in vitro response and in vivo encapsulation outcomes is not robust. Adverse outcome pathways (AOPs) offer a potential framework to understand and predict process complexity. AOPs describe causal relationships between measurable events leading to adverse outcomes, providing mechanistic insights for in vitro testing and predictive modeling. However, the development of an AOP for the FBR does require a comprehensive understanding of the molecular initiating events and key event relationships to identify which events are essential. In this article, we describe the current knowledge on macrophage-fibroblast cross talk in the FBR and discuss how targeted research can help build an AOP for implant-related fibrosis.

A critical evaluation of suitability of tralokinumab for treatment of moderate-to-severe atopic dermatitis in adolescents and adults

INTRODUCTION

Atopic dermatitis (AD) is a chronic, intensely pruritic disease associated with significant patient burden. Recent advancements in AD pathogenesis have expanded its therapeutics pipeline. Tralokinumab is a fully human monoclonal antibody that binds specifically Interleukin (IL)-13, inhibiting the downstream IL-13 signaling. Phase 3 clinical trials and some real-world studies showed that tralokinumab, as monotherapy or in combination with topical corticosteroids, is efficacious and safe in adult patients with moderate-to-severe AD. Similar results were reported in a phase 3 trial in adolescents (aged ≥12 years).

AREAS COVERED

We review the role of IL-13 in AD and discuss the value of tralokinumab for treating moderate-to-severe AD, comparing efficacy and safety results derived from clinical trials and real-life data.

EXPERT OPINION

The role of IL-13 in AD supports a targeted therapeutic approach. Tralokinumab has proven efficacious and well-tolerated in a large proportion of patients confirming its value for treating moderate-to-severe AD from age 12 years onwards; it quickly improves itching and can maintain a high-level of response over time; it can be administered with flexible dosing schedules. Future studies will further clarify the role of IL-13 pathway and which patients would be best suited to tralokinumab, shifting AD treatment into an era of precision medicine.

Cardiac regeneration: Pre-existing cardiomyocyte as the hub of novel signaling pathway

In the mammalian heart, cardiomyocytes are forced to withdraw from the cell cycle shortly after birth, limiting the ability of the heart to regenerate and repair. The development of multimodal regulation of cardiac proliferation has verified that pre-existing cardiomyocyte proliferation is an essential driver of cardiac renewal. With the continuous development of genetic lineage tracking technology, it has been revealed that cell cycle activity produces polyploid cardiomyocytes during the embryonic, juvenile, and adult stages of cardiogenesis, but newly formed mononucleated diploid cardiomyocytes also elevated sporadically during myocardial infarction. It implied that adult cardiomyocytes have a weak regenerative capacity under the condition of ischemia injury, which offers hope for the clinical treatment of myocardial infarction. However, the regeneration frequency and source of cardiomyocytes are still low, and the mechanism of regulating cardiomyocyte proliferation remains further explained. It is noteworthy to explore what force triggers endogenous cardiomyocyte proliferation and heart regeneration. Here, we focused on summarizing the recent research progress of emerging endogenous key modulators and crosstalk with other signaling pathways and furnished valuable insights into the internal mechanism of heart regeneration. In addition, myocardial transcription factors, non-coding RNAs, cyclins, and cell cycle-dependent kinases are involved in the multimodal regulation of pre-existing cardiomyocyte proliferation. Ultimately, awakening the myocardial proliferation endogenous modulator and regeneration pathways may be the final battlefield for the regenerative therapy of cardiovascular diseases.

Deciphering the fibrotic process: mechanism of chronic radiation skin injury fibrosis

This review explores the mechanisms of chronic radiation-induced skin injury fibrosis, focusing on the transition from acute radiation damage to a chronic fibrotic state. It reviewed the cellular and molecular responses of the skin to radiation, highlighting the role of myofibroblasts and the significant impact of Transforming Growth Factor-beta (TGF-β) in promoting fibroblast-to-myofibroblast transformation. The review delves into the epigenetic regulation of fibrotic gene expression, the contribution of extracellular matrix proteins to the fibrotic microenvironment, and the regulation of the immune system in the context of fibrosis. Additionally, it discusses the potential of biomaterials and artificial intelligence in medical research to advance the understanding and treatment of radiation-induced skin fibrosis, suggesting future directions involving bioinformatics and personalized therapeutic strategies to enhance patient quality of life.

Human germline gain-of-function in STAT6: from severe allergic disease to lymphoma and beyond

Signal transducer and activator of transcription (STAT)-6 is a transcription factor central to pro-allergic immune responses, although the function of human STAT6 at the whole-organism level has long remained unknown. Germline heterozygous gain-of-function (GOF) rare variants in STAT6 have been recently recognized to cause a broad and severe clinical phenotype of early-onset, multi-system allergic disease. Here, we provide an overview of the clinical presentation of STAT6-GOF disease, discussing how dysregulation of the STAT6 pathway causes severe allergic disease, and identifying possible targeted treatment approaches. Finally, we explore the mechanistic overlap between STAT6-GOF disease and other monogenic atopic disorders, and how this group of inborn errors of immunity (IEIs) powerfully inform our fundamental understanding of common human allergic disease.

Fibroblasts and immune cells: at the crossroad of organ inflammation and fibrosis

The immune and fibrotic responses have evolved to work in tandem to respond to pathogen clearance and promote tissue repair. However, excessive immune and fibrotic responses lead to chronic inflammation and fibrosis, respectively, both of which are key pathological drivers of organ pathophysiology. Fibroblasts and immune cells are central to these responses, and evidence of these two cell types communicating through soluble mediators or adopting functions from each other through direct contact is constantly emerging. Here, we review complex junctions of fibroblast-immune cell cross talk, such as immune cell modulation of fibroblast physiology and fibroblast acquisition of immune cell-like functions, as well as how these systems of communication contribute to organ pathophysiology. We review the concept of antigen presentation by fibroblasts among different organs with different regenerative capacities, and then focus on the inflammation-fibrosis axis in the heart in the complex syndrome of heart failure. We discuss the need to develop anti-inflammatory and antifibrotic therapies, so far unsuccessful to date, that target novel mechanisms that sit at the crossroads of the fibrotic and immune responses.

Cytokine, chemokine alterations and immune cell infiltration in Radiation-induced lung injury: Implications for prevention and management

Radiation therapy is one of the primary treatments for thoracic malignancies, with radiation-induced lung injury (RILI) emerging as its most prevalent complication. RILI encompasses early-stage radiation pneumonitis (RP) and the subsequent development of radiation pulmonary fibrosis (RPF). During radiation treatment, not only are tumor cells targeted, but normal tissue cells, including alveolar epithelial cells and vascular endothelial cells, also sustain damage. Within the lungs, ionizing radiation boosts the intracellular levels of reactive oxygen species across various cell types. This elevation precipitates the release of cytokines and chemokines, coupled with the infiltration of inflammatory cells, culminating in the onset of RP. This pulmonary inflammatory response can persist, spanning a duration from several months to years, ultimately progressing to RPF. This review aims to explore the alterations in cytokine and chemokine release and the influx of immune cells post-ionizing radiation exposure in the lungs, offering insights for the prevention and management of RILI.

Treatment with a red-laser-based wound therapy device exerts positive effects in models of delayed keratinocyte and fibroblast wound healing

BACKGROUND

Light therapy is widely used in medicine. Specifically, photobiomodulation has been shown to exert beneficial effects in wound healing disorders, which present a major challenge in health care. The study's aim was providing information on the effect of a novel, red-laser-based wound therapy device (WTD) on keratinocytes and fibroblasts during wound healing under optimal and non-optimal conditions.

METHODS

The scratch wound assay was employed as a wound healing model for mechanical damage with readjustment of specific cell milieus, explicitly chronic TH1 inflammation and TH2-dominant conditions. Furthermore, gene expression analysis of pro-inflammatory cytokines (IL1A, IL6, CXCL8), growth factors (TGFB1, PDGFC), transcription factors (NFKB1, TP53) and heat shock proteins (HSP90AA1, HSPA1A, HSPD1) as well as desmogleins (DSG1, DSG3) in keratinocytes and collagen (COL1A1, COL3A1) in fibroblasts was performed after WTD treatment.

RESULTS

It was shown that WTD treatment is biocompatible and supports scratch wound closure under non-optimal conditions. A distinct enhancement of desmoglein and collagen gene expression as well as induction of early growth factor gene expression was observed under chronic inflammatory conditions. Moreover, WTD increased HSPD1 transcript levels in keratinocytes and augmented collagen expression in fibroblasts during wound healing under TH2 conditions. WTD treatment also alleviated the inflammatory response in keratinocytes and induced early growth factor gene expression in fibroblasts under physiological conditions.

CONCLUSION

Positive effects described for wound treatment with WTD could be replicated in vitro and seem to be to be conferred by a direct influence on cellular processes taking place in keratinocytes and fibroblasts during wound healing.

Expression of miR-21 &IL-4 in endometriosis

BACKGROUND

Endometriosis characterized with existence of endometrial-like tissue outside the uterus. Fibrosis of ectopic lesions is an important feature of endometriosis. IL-4 induces fibrosis via fibroblast proliferation, collagen production and myofibroblast differentiation. Increasing of miR-21 expression promotes fibroblast activation and fibrosis expansion. The aim of study was to evaluate the expression of miR-21 and its relationship with IL-4 gene expression in endometrial ectopic and eutopic tissues of endometriosis patients.

METHODS AND RESULTS

Ectopic and eutopic tissue samples were taken from 20 women with endometriosis, and control samples were taken from the endometrium of 20 endometriosis-free women. The relative expression of IL-4 and miR-21 evaluated by Real Time PCR. IL-4 relative gene expression was significantly increased in ectopic tissue compared to eutopic (p = 0.025) and control tissue (p = 0.021). The relative expression of miR-21 gene in ectopic tissue was increased compared to eutopic (p = 0.850) and control tissue (p = 0.978) but these differences were not significant. Also, the correlation between IL-4 and miR-21 relative gene expression was not significant (p = 0.083).

CONCLUSION

The increased expression of miR-21 in endometrium of women with endometriosis may upregulate the IL-4 gene expression and lead to fibrosis. Further studies may suggest miR-21 and IL-4 as candidates for diagnosis of endometriosis.

Crosstalk between fibroblasts and immunocytes in fibrosis: From molecular mechanisms to clinical trials

BACKGROUND

The impact of fibroblasts on the immune system provides insight into the function of fibroblasts. In various tissue microenvironments, multiple fibroblast subtypes interact with immunocytes by secreting growth factors, cytokines, and chemokines, leading to wound healing, fibrosis, and escape of cancer immune surveillance. However, the specific mechanisms involved in the fibroblast-immunocyte interaction network have not yet been fully elucidated.

MAIN BODY AND CONCLUSION

Therefore, we systematically reviewed the molecular mechanisms of fibroblast-immunocyte interactions in fibrosis, from the history of cellular evolution and cell subtype divisions to the regulatory networks between fibroblasts and immunocytes. We also discuss how these communications function in different tissue and organ statuses, as well as potential therapies targeting the reciprocal fibroblast-immunocyte interplay in fibrosis. A comprehensive understanding of these functional cells under pathophysiological conditions and the mechanisms by which they communicate may lead to the development of effective and specific therapies targeting fibrosis.

The Molecular Mechanisms Involved in the Hypertrophic Scars Post-Burn Injury

Scar formation is a normal response to skin injuries. During the scar-remodeling phase, scar tissue is usually replaced with normal, functional tissue. However, after deep burn injuries, the scar tissue may persist and lead to contractures around joints, a condition known as hypertrophic scar tissue. Unfortunately, current treatment options for hypertrophic scars, such as surgery and pressure garments, often fail to prevent their reappearance. One of the primary challenges in treating hypertrophic scars is a lack of knowledge about the molecular mechanisms underlying their formation. In this review, we critically analyze studies that have attempted to uncover the molecular mechanisms behind hypertrophic scar formation after severe burn injuries, as well as clinical trials conducted to treat post-burn hypertrophic scars. We found that most clinical trials used pressure garments, laser treatments, steroids, and proliferative inhibitors for hypertrophic scars, with outcomes measured using subjective scar scales. However, fundamental research using human burn injury biopsies has shown that pathways such as Transforming Growth factor β (TGFβ), Phosphatase and tensin homolog (PTEN), and Toll-like receptors (TLRs) could be potentially regulated to reduce scarring. Therefore, we conclude that more testing is necessary to determine the efficacy of these molecular targets in reducing hypertrophic scarring. Specifically, double-blinded clinical trials are needed, where the outcomes can be measured with more robust quantitative molecular parameters.

IL-13 neutralization attenuates carotid artery intimal hyperplasia and increases endothelial cell migration via modulating the JAK-1/STAT-3 signaling pathway

The aim of this study was to investigate how the concentration of interleukin-13 (IL-13) affects the regulation of endothelial cell migration after injury. The incubation of recombinant human interleukin-13 (rhIL-13) strongly increased the content of reactive oxygen species (ROS) in HUVECs via the JAK-1/STAT-3/NOX-4 signaling pathway. Antagonizing the high intracellular ROS that was induced by rhIL-13 promoted the migration of HUVECs. Furthermore, IL-13 neutralization not only inhibited intimal hyperplasia, but also promoted the migration of endothelial cells (ECs) after injury. The results suggest that IL-13 inhibition is a potential means of stimulating endothelial cells recovery after injury. Therefore, the attenuation of IL-13 activation may have therapeutic value for vascular disease.

Integration of transcriptomes of senescent cell models with multi-tissue patient samples reveals reduced COL6A3 as an inducer of senescence

Senescent cells are a major contributor to age-dependent cardiovascular tissue dysfunction, but knowledge of their in vivo cell markers and tissue context is lacking. To reveal tissue-relevant senescence biology, we integrate the transcriptomes of 10 experimental senescence cell models with a 224 multi-tissue gene co-expression network based on RNA-seq data of seven tissues biopsies from ∼600 coronary artery disease (CAD) patients. We identify 56 senescence-associated modules, many enriched in CAD GWAS genes and correlated with cardiometabolic traits-which supports universality of senescence gene programs across tissues and in CAD. Cross-tissue network analyses reveal 86 candidate senescence-associated secretory phenotype (SASP) factors, including COL6A3. Experimental knockdown of COL6A3 induces transcriptional changes that overlap the majority of the experimental senescence models, with cell-cycle arrest linked to modulation of DREAM complex-targeted genes. We provide a transcriptomic resource for cellular senescence and identify candidate biomarkers, SASP factors, and potential drivers of senescence in human tissues.

Scars

Wound healing occurs as a response to disruption of the epidermis and dermis. It is an intricate and well-orchestrated response with the goal to restore skin integrity and function. However, in hundreds of millions of patients, skin wound healing results in abnormal scarring, including keloid lesions or hypertrophic scarring. Although the underlying mechanisms of hypertrophic scars and keloid lesions are not well defined, evidence suggests that the changes in the extracellular matrix are perpetuated by ongoing inflammation in susceptible individuals, resulting in a fibrotic phenotype. The lesions then become established, with ongoing deposition of excess disordered collagen. Not only can abnormal scarring be debilitating and painful, it can also cause functional impairment and profound changes in appearance, thereby substantially affecting patients' lives. Despite the vast demand on patient health and the medical society, very little progress has been made in the care of patients with abnormal scarring. To improve the outcome of pathological scarring, standardized and innovative approaches are required.

Skin Homeostasis and Repair: A T Lymphocyte Perspective

Chronic, nonhealing wounds remain a clinical challenge and a significant burden for the healthcare system. Skin-resident and infiltrating T cells that recognize pathogens, microbiota, or self-antigens participate in wound healing. A precise balance between proinflammatory T cells and regulatory T cells is required for the stages of wound repair to proceed efficiently. When diseases such as diabetes disrupt the skin microenvironment, T cell activation and function are altered, and wound repair is hindered. Recent studies have used cutting-edge technology to further define the cellular makeup of the skin prior to and during tissue repair. In this review, we discuss key advances that highlight mechanisms used by T cell subsets to populate the epidermis and dermis, maintain skin homeostasis, and regulate wound repair. Advances in our understanding of how skin cells communicate in the skin pave the way for therapeutics that modulate regulatory versus effector functions to improve nonhealing wound treatment.

Type 2 cytokines and scleroderma interstitial lung disease

Interstitial lung disease (ILD) is a life-threatening complication of systemic sclerosis (SSc). Type 2 (Th2) cytokines play a pivotal role in airway disease. Study aim was to evaluate serum level of Th2 interleukin (IL) and chemokine in SSc-ILD. Serum levels of IL-4, IL-5, IL-11, IL-13, IL-21, IL-31 and CXCL-13 were measured by Bio-Plex Multiplex Immunoassays in 60 SSc patients and 20 healthy controls (HC). Pulmonary function tests with diffusion lung capacity for carbon monoxide (DLco) and high resolution computed tomography (HRCT) were performed in SSc patients. ILD is defined as fibrotic changes (ground glass, reticular and honeycombing), assessed by Computer-Aided Lung Informatics for Pathology Evaluation and Ratings (CALIPER) software, affecting at least 10% of the lungs. Serum levels of Th2 cytokines were higher in SSc patients than HC. A linear correlation was observed between ground glass and IL-13 (r = 0.342, p < 0.01), IL-21 (r = 0.345, p < 0.01), IL-31 (r = 0.473, p < 0.001), IL-4 (r = 0.863, p < 0.001), IL-5 (r = 0.249, p < 0.05) and peripheral blood eosinophils (r = 0.463, p < 0.001). We found a negative correlation between DLco and IL-4 (r =  - 0.511, p < 0.001) and peripheral blood eosinophils (r =  - 0.446, p < 0.001). In the logistic regression analysis, IL-4 is associated with DLco ≤ 60% of the predicted [OR 1.039 (CI 95%: 1.015-1.064), p < 0.001], whilst mRSS [OR 1.138 (CI 95%: 1.023-1.266), p < 0.05] and IL-4 [OR 1.017 (CI 95%: 1-1.034), p < 0.05] were associated with ILD. Th2 inflammation could play a key role in early phase of SSc-ILD.

Pro-Fibrotic Role of Interleukin-4 in Influencing Idiopathic Epiretinal Membrane in Cataract Patients: Analysis From Clinical-Experimental Approaches

Purpose

To evaluate the role of interleukin-4 in influencing idiopathic epiretinal membrane (iERM) formation and early progression post cataract surgery (PCS) from clinical and experimental perspectives.

Methods

We quantified levels of IL-4 in aqueous humor (AH) samples from 22 iERM patients and 31 control subjects collected before and 20 hours after cataract surgeries using ELISA. After a 3-month follow-up, the association between IL-4 levels and iERM progression measurements was identified. In addition, in vitro studies were conducted to investigate the effects of IL-4 on primary rat retinal Müller glia proliferation, migration, and glial-mesenchymal transition (GMT).

Results

Concentrations of IL-4 were significantly higher in preoperative AH samples from iERM patients versus controls (P = 0.006). Postoperatively, although IL-4 levels were elevated in both groups compared to their respective preoperative levels, they were even more obviously so in the iERM group (P < 0.001). Multivariate linear regression analyses revealed that, postoperatively, IL-4 level elevation was positively associated with macular volume and thickness increase (both P < 0.05) in iERM patients. However, no correlations were observed between IL-4 level (changes) and clinical characters in the controls. In vitro studies demonstrated that IL-4 promoted Müller glia proliferation and migration and increased the expression of GMT-related markers in a manner independent of transforming growth factor-β1 (TGF-β1).

Conclusions

IL-4 plays a crucial pro-fibrotic role in iERM formation and early progression 3 months PCS possibly by stimulating Müller glia proliferation, migration, and GMT in a TGF-β1-independent manner.

Translational Relevance

The current study suggests the potential of IL-4 as a novel therapeutic target for iERM.

Pruritus in keloid scars: mechanisms and treatments

Keloids occur after cutaneous injury and can cause distress due to physical appearance and associated symptoms such as pain and pruritus. Keloid-associated pruritus is a common manifestation and has negative impacts on quality of life. The mechanism underlying this type of pruritus is multifactorial and thought to involve small nerve fiber damage, neurogenic inflammation, and a Th2-predominant inflammatory response. Various agents have been shown to reduce keloid pruritus, including intralesional corticosteroids, botulinum toxin A, 5-fluorouracil, and bleomycin. Other treatment modalities such as cryotherapy and hyperbaric oxygen therapy are also effective. Future treatments targeting the mechanisms involved in keloid-associated itch could provide improvements in pruritus and quality of life in these patients, but further studies on the efficacy of these agents are needed.

Transcriptomic profiling of mare endometrium at different stages of endometrosis

In the current study, transcriptome profiles of mare endometrium, classified into categories I, IIA, and IIB according to Kenney and Doig, were compared using RNA sequencing, analyzed, and functionally annotated using in silico analysis. In the mild stage (IIA) of endometrosis compared to category I endometrium, differentially expressed genes (DEGs) were annotated to inflammation, abnormal metabolism, wound healing, and quantity of connective tissue. In the moderate stage (IIB) of endometrosis compared to category I endometrium, DEGs were annotated to inflammation, fibrosis, cellular homeostasis, mitochondrial dysfunction, and pregnancy disorders. Ingenuity pathway analysis (IPA) identified cytokines such as transforming growth factor (TGF)-β1, interleukin (IL)-4, IL-13, and IL-17 as upstream regulators of DEGs associated with cellular homeostasis, metabolism, and fibrosis signaling pathways. In vitro studies showed the effect of these cytokines on DEGs such as ADAMTS1, -4, -5, -9, and HK2 in endometrial fibroblasts at different stages of endometrosis. The effect of cytokines on ADAMTS members' gene transcription in fibroblasts differs according to the severity of endometrosis. The identified transcriptomic changes associated with endometrosis suggest that inflammation and metabolic changes are features of mild and moderate stages of endometrosis. The changes of ADAMTS-1, -4, -5, -9, in fibrotic endometrium as well as in endometrial fibroblast in response to TGF-β1, IL-4, IL-13, and IL-17 suggest the important role of these factors in the development of endometrosis.

Functionally Relevant Cytokine/Receptor Axes in Myelofibrosis

Dysregulated inflammatory signaling is a key feature of myeloproliferative neoplasms (MPNs), most notably of myelofibrosis (MF). Indeed, MF is considered the prototype of onco-inflammatory hematologic cancers. While increased levels of circulatory and bone marrow cytokines are a well-established feature of all MPNs, a very recent body of literature is intriguingly pinpointing the selective overexpression of cytokine receptors by MF hematopoietic stem and progenitor cells (HSPCs), which, by contrast, are nearly absent or scarcely expressed in essential thrombocythemia (ET) or polycythemia vera (PV) cells. This new evidence suggests that MF CD34+ cells are uniquely capable of sensing inflammation, and that activation of specific cytokine signaling axes may contribute to the peculiar aggressive phenotype and biological behavior of this disorder. In this review, we will cover the main cytokine systems peculiarly activated in MF and how cytokine receptor targeting is shaping a novel therapeutic avenue in this disease.

Type 2 chronic inflammatory diseases: targets, therapies and unmet needs

Over the past two decades, significant progress in understanding of the pathogenesis of type 2 chronic inflammatory diseases has enabled the identification of compounds for more than 20 novel targets, which are approved or at various stages of development, finally facilitating a more targeted approach for the treatment of these disorders. Most of these newly identified pathogenic drivers of type 2 inflammation and their corresponding treatments are related to mast cells, eosinophils, T cells, B cells, epithelial cells and sensory nerves. Epithelial barrier defects and dysbiotic microbiomes represent exciting future drug targets for chronic type 2 inflammatory conditions. Here, we review common targets, current treatments and emerging therapies for the treatment of five major type 2 chronic inflammatory diseases - atopic dermatitis, chronic prurigo, chronic urticaria, asthma and chronic rhinosinusitis with nasal polyps - with a high need for targeted therapies. Unmet needs and future directions in the field are discussed.

Recent advances in strategies to target the behavior of macrophages in wound healing

Chronic wounds and scar formation are widespread due to limited suitable remedies. The macrophage is a crucial regulator in wound healing, controlling the onset and termination of inflammation and regulating other processes related to wound healing. The current breakthroughs in developing new medications and drug delivery methods have enabled the accurate targeting of macrophages in oncology and rheumatic disease therapies through clinical trials. These successes have cleared the way to utilize drugs targeting macrophages in various disorders. This review thus summarizes macrophage involvement in normal and pathologic wound healing. It further details the targets available for macrophage intervention and therapeutic strategies for targeting the behavior of macrophages in tissue repair and regeneration.

An Open-Label, Uncontrolled, Single-Arm Clinical Trial of Tofacitinib, an Oral JAK1 and JAK3 Kinase Inhibitor, in Chinese Patients with Keloid

BACKGROUND

The keloid treatment is still a thorny and complicated clinical problem, especially in multiple keloids induced by wound, severe burn, ethnic background or cultural behaviors, or unexplained skin healing. Mainstream treatments have limited efficacy in treating multiple keloids. As no oral treatment with painlessness and convenience is available, oral treatment strategies should be formulated.

OBJECTIVES

This study aimed to investigate the efficacy and therapeutic mechanism of oral tofacitinib in keloid patients.

METHODS

We recruited the 7 patients with keloid scars and prescribed 5 mg of tofacitinib twice a day orally with a maximum follow-up of 12 weeks. The Patient and Observer Scar Assessment Scale (POSAS), the Vancouver scar scale (VSS), ANTERA 3D camera, and the DUB Skin Scanner 75 were used to assess the characteristics of the lesion. Immunohistochemistry was performed to evaluate collagen synthesis, proliferation, and relative molecular pathways. Moreover, the effects of tofacitinib were assessed on keloid fibroblast in vitro.

RESULTS

After 12 weeks of oral tofacitinib, significant improvement in POSAS, VSS, and Dermatology Life Quality Index (DLQI) scores was observed (p < 0.05). The volume, lesion height, and dermis thickness of the keloid decreased (p < 0.05). Moreover, significant decreases in the expression of collagen I, Ki67, p-STAT 3, and p-SMAD2 were observed after 12 weeks of administration. In vitro experiments suggested that tofacitinib treatment inhibits fibroblast proliferation and collagen I synthesis via suppression of STAT3 and SMAD2 pathway.

CONCLUSION

Tofacitinib, a new candidate oral drug for keloid, could reduce keloid lesion volume by inhibiting collagen synthesis and inhibiting fibroblast proliferation, and alleviate itch and pain to obtain a better life quality.

Multimodal roles of transient receptor potential channel activation in inducing pathological tissue scarification

Transient receptor potential (TRP) channels are a class of transmembrane proteins that can sense a variety of physical/chemical stimuli, participate in the pathological processes of various diseases and have attracted increasing attention from researchers. Recent studies have shown that some TRP channels are involved in the development of pathological scarification (PS) and directly participate in PS fibrosis and re-epithelialization or indirectly activate immune cells to release cytokines and neuropeptides, which is subdivided into immune inflammation, fibrosis, pruritus and mechanical forces increased. This review elaborates on the characteristics of TRP channels, the mechanism of PS and how TRP channels mediate the development of PS, summarizes the important role of TRP channels in the different pathogenesis of PS and proposes that therapeutic strategies targeting TRP will be important for the prevention and treatment of PS. TRP channels are expected to become new targets for PS, which will make further breakthroughs and provide potential pharmacological targets and directions for the in-depth study of PS.

Interleukin-13 (IL-13)-A Pleiotropic Cytokine Involved in Wound Healing and Fibrosis

The liver, as a central metabolic organ, is systemically linked to metabolic-inflammatory diseases. In the pathogenesis of the metabolic syndrome, inflammatory and metabolic interactions between the intestine, liver, and adipose tissue lead to the progression of hepatic steatosis to metabolic-dysfunction-associated steatohepatitis (MASH) and consecutive MASH-induced fibrosis. Clinical and animal studies revealed that IL-13 might be protective in the development of MASH through both the preservation of metabolic functions and Th2-polarized inflammation in the liver and the adipose tissue. In contrast, IL-13-associated loss of mucosal gut barrier function and IL-13-associated enhanced hepatic fibrosis may contribute to the progression of MASH. However, there are only a few publications on the effect of IL-13 on metabolic diseases and possible therapies to influence them. In this review article, different aspects of IL-13-associated effects on the liver and metabolic liver diseases, which are partly contradictory, are summarized and discussed on the basis of the recent literature.

Evidence-based management of keloids and hypertrophic scars in dermatology

While normal, controlled wound-healing results in scars that are nearly imperceptible, hypertrophic scars (HTS) and keloids are the result of an abnormal wound-healing process that can leave unsightly, difficult-to-treat lesions. While such scars are classically associated with surgical incisions, they may also result from burns or accidental trauma to the skin. Several different measures can be taken to prevent the formation of scars or treat those that have already formed. Prevention focuses on reducing inflammation during the wound-healing process, and minimizing tension in the lesion when appropriate. Treatments range from non-invasive modalities such as pressure therapy, topicals, and symptom management, to invasive methods such as injections, lasers, and even surgery. While some treatments, such as corticosteroid injections, have been used in the treatment of HTS and keloids for decades, other newer therapies have only been described in case reports or are still in early phases of clinical trials. Because optimal scar management will not be the same for every patient, further investigation of newer agents and methods is warranted and may benefit a great number of patients. This paper will review the evidence-based management of scars, including current widely used treatment options and promising newly emerging therapies.

Roles of the HIF-1α pathway in the development and progression of keloids

Keloids, a pathological scar that is induced by the consequence of aberrant wound healing, is still a major global health concern for its unsatisfactory treatment outcomes. HIF-1α, a main regulator of hypoxia, mainly acts through some proteins or signaling pathways and plays important roles in a variety of biological processes. Accumulating evidence has shown that HIF-1α played a crucial role in the process of keloid formation. In this review, we attempted to summarize the current knowledge on the association between HIF-1α expression and the development and progression of keloids. Through a comprehensive analysis, the molecular mechanisms underlying HIF-1α in keloids were shown to be correlated to the proliferation of fibroblasts, angiogenesis, and collagen deposits. The affected proteins and the signaling pathways were multiple. For instance, HIF-1α was reported to promote keloids formation by enhancing angiogenesis, fibroblast proliferation, and collagen deposition through the activation of periostin PI3K/Akt, TGF-β/Smad and TLR4/MyD88/NF-κB pathway. However, the specific effects of HIF-1α on keloids keloid illnesses in clinical practice is are entirely unclear, and further studies in clinical trials are still warranted. Therefore, an in-depth understanding of the biological mechanisms of HIF-1α in keloid formation is significant to develop promising therapeutic targets for the treatment of keloids in clinical practice.

Exploring the contribution of pro-inflammatory cytokines to impaired wound healing in diabetes

Background

Impaired wound healing is the most common and significant complication of Diabetes. While most other complications of Diabetes have better treatment options, diabetic wounds remain a burden as they can cause pain and suffering in patients. Wound closure and repair are orchestrated by a sequence of events aided by the release of pro-inflammatory cytokines, which are dysregulated in cases of Diabetes, making the wound environment unfavorable for healing and delaying the wound healing processes. This concise review provides an overview of the dysregulation of pro-inflammatory cytokines and offers insights into better therapeutic outcomes.

Purpose of review

Although many therapeutic approaches have been lined up nowadays to treat Diabetes, there are no proper treatment modalities proposed yet in treating diabetic wounds due to the lack of understanding about the role of inflammatory mediators, especially Pro-inflammatory mediators- Cytokines, in the process of Wound healing which we mainly focus on this review.

Recent findings

Although complications of Diabetes mellitus are most reported after years of diagnosis, the most severe critical complication is impaired Wound Healing among Diabetes patients. Even though Trauma, Peripheral Artery Disease, and Peripheral Neuropathy are the leading triggering factors for the development of ulcerations, the most significant issue contributing to the development of complicated cutaneous wounds is wound healing impairment. It may even end up with amputation. Newer therapeutic approaches such as incorporating the additives in the present dressing materials, which include antimicrobial molecules and immunomodulatory cytokines is of better therapeutic value.

Summary

The adoption of these technologies and the establishment of novel therapeutic interventions is difficult since there is a gap in terms of a complete understanding of the pathophysiological mechanisms at the cellular and molecular level and the lack of data in terms of the assessment of safety and bioavailability differences in the individuals' patients. The target-specific pro-inflammatory cytokines-based therapies, either by upregulation or downregulation of them, will be helpful in the wound healing process and thereby enhances the Quality of life in patients, which is the goal of drug therapy.

Novel Therapeutic Strategies in the Treatment of Systemic Sclerosis

Systemic sclerosis is a connective tissue disease of unknown origin and with an unpredictable course, with both cutaneous and internal organ manifestations. Despite the enormous progress in rheumatology and clinical immunology, the background of this disease is largely unknown, and no specific therapy exists. The therapeutic approach aims to treat and preserve the function of internal organs, and this approach is commonly referred to as organ-based treatment. However, in modern times, data from other branches of medicine may offer insight into how to treat disease-related complications, making it possible to find new drugs to treat this disease. In this review, we present therapeutic options aiming to stop the progression of fibrotic processes, restore the aberrant immune response, stop improper signalling from proinflammatory cytokines, and halt the production of disease-related autoantibodies.

Advances in Immunomodulatory Mechanisms of Mesenchymal Stem Cells-Derived Exosome on Immune Cells in Scar Formation

Pathological scars are the result of over-repair and excessive tissue proliferation of the skin injury. It may cause serious dysfunction, resulting in psychological and physiological burdens on the patients. Currently, mesenchymal stem cells-derived exosomes (MSC-Exo) displayed a promising therapeutic effect on wound repair and scar attenuation. But the regulatory mechanisms are opinions vary. In view of inflammation has long been proven as the initial factor of wound healing and scarring, and the unique immunomodulation mechanism of MSC-Exo, the utilization of MSC-Exo may be promising therapeutic for pathological scars. However, different immune cells function differently during wound repair and scar formation. The immunoregulatory mechanism of MSC-Exo would differ among different immune cells and molecules. Herein, this review gave a comprehensive summary of MSC-Exo immunomodulating different immune cells in wound healing and scar formation to provide basic theoretical references and therapeutic exploration of inflammatory wound healing and pathological scars.

Binding, Neutralization and Internalization of the Interleukin-13 Antibody, Lebrikizumab

INTRODUCTION

IL-13 is the primary upregulated cytokine in atopic dermatitis (AD) skin and is the pathogenic mediator driving AD pathophysiology. Lebrikizumab, tralokinumab and cendakimab are therapeutic monoclonal antibodies (mAb) that target IL-13.

METHODS

We undertook studies to compare in vitro binding affinities and cell-based functional activities of lebrikizumab, tralokinumab and cendakimab.

RESULTS

Lebrikizumab bound IL-13 with higher affinity (as determined using surface plasma resonance) and slower off-rate. It was more potent in neutralizing IL-13-induced effects in STAT6 reporter and primary dermal fibroblast periostin secretion assays than either tralokinumab or cendakimab. Live imaging confocal microscopy was employed to determine the mAb effects on IL-13 internalization into cells via the decoy receptor IL-13Rα2, using A375 and HaCaT cells. The results showed that only the IL-13/lebrikizumab complex was internalized and co-localized with lysosomes, whereas IL-13/tralokinumab or IL-13/cendakimab complexes did not internalize.

CONCLUSION

Lebrikizumab is a potent, neutralizing high-affinity antibody with a slow disassociation rate from IL-13. Additionally, lebrikizumab does not interfere with IL-13 clearance. Lebrikizumab has a different mode of action to both tralokinumab and cendakimab, possibly contributing to the clinical efficacy observed by lebrikizumab in Ph2b/3 AD studies.

Dupilumab in patients with prurigo nodularis: two randomized, double-blind, placebo-controlled phase 3 trials

Prurigo nodularis (PN) is a chronic inflammatory skin disease with intensely pruritic nodules. The LIBERTY-PN PRIME and PRIME2 phase 3 trials enrolled adults with PN with ≥20 nodules and severe itch uncontrolled with topical therapies. Dupilumab, a fully human monoclonal antibody, blocks the shared receptor component for interleukin (IL)-4 and IL-13. Patients were randomized 1:1 to 300 mg dupilumab or placebo subcutaneously every 2 weeks for 24 weeks. The primary endpoint was pruritus improvement, measured by proportion of patients with a ≥4-point reduction in Worst Itch Numeric Rating Scale (WI-NRS) from baseline at week 24 (PRIME) or week 12 (PRIME2). Key secondary endpoints included nodule number reduction to ≤5 at week 24. PRIME and PRIME2 enrolled 151 and 160 patients, respectively. Both trials met all the pre-specified primary and key secondary endpoints. A ≥4-point WI-NRS reduction at week 24 in the dupilumab and placebo arms was achieved by 60.0% and 18.4% of patients, respectively, in PRIME (95% confidence interval (CI), 27.8-57.7 for the difference, P < 0.001) and at week 12 by 37.2% and 22.0% of patients, respectively, in PRIME2 (95% CI, 2.3-31.2; P = 0.022). Dupilumab demonstrated clinically meaningful and statistically significant improvements in itch and skin lesions versus placebo in PN. Safety was consistent with the known dupilumab safety profile.ClinicalTrials.gov identifiers: NCT04183335 and NCT04202679 .

Therapeutic effects of Pulsatilla koreana Nakai extract on ovalbumin-induced allergic rhinitis by inhibition of Th2 cell activation and differentiation via the IL-4/STAT6/GATA3 pathway

Allergic rhinitis (AR), caused by immunoglobulin E (IgE)-mediated inflammation, generally occurs in the upper respiratory tract. T helper type 2 (Th2) cell-mediated cytokines, including interleukin (IL)-4, IL-5, and IL-13, are important factors in AR pathogenesis. Despite various treatment options, the difficulty in alleviating AR and pharmacological side effects necessitate development of new therapies. The root of Pulsatilla koreana Nakai (P. koreana), a pasque flower, has been used as a herbal medicine. However, its effects on AR remain unclear; therefore, we aimed to explore this subject in the current study. The therapeutic effects of P. koreana water extract (PKN) on the pathophysiological functions of the nasal mucosa was examined in ovalbumin (OVA)-induced AR mice. The effect of PKN on Th2 activation and differentiation was evaluated using concanavalin A-induced splenocytes and differentiated Th2 cells from naïve CD4⁺ T cells. We also investigated the effect of changes in JAK/STAT6/GATA3 signaling on IL-4-induced Th2 cells. In OVA-induced AR mice, PKN administration alleviated allergic nasal symptoms and decreased the total number of immune cells, lymphocytes, neutrophils, and eosinophils in nasal lavage fluid; serum levels of OVA-specific IgE, histamine, and IL-13 were also significantly reduced. PKN also ameliorated OVA-induced nasal mucosal tissue thickening by inhibiting inflammation and goblet cell hyperplasia. PKN treatment significantly inhibited Th2 activity and differentiation through the IL-4/STAT-6/GATA3 pathway in Th2 cells. PKN is an effective AR treatment with the potential to improve patients' daily lives by regulating the allergic inflammatory response induced by Th2 cells.

Over 90% Percent of Childhood BCG Vaccine-Induced Keloids in Japan Occur in Women

INTRODUCTION

Keloids are a fibroproliferative, multifactorial, cutaneous disorder whose pathophysiology is not completely understood. Various factors such as high blood pressure, pregnancy, female gender, mechanical tension of local sites, and prolonged wound healing are known to worsen keloids. Childhood-onset keloids are keloids that form before 10 years of age, before various factors in adulthood come into play, and thus studying childhood-onset keloids may provide additional insight into the underlying mechanisms that lead to keloid formation.

METHODS

Retrospective chart review was performed on all patients with childhood-onset keloids who were evaluated at our plastic surgery clinic (one of the largest keloid referral centers in Japan) over a 1-year period.

RESULTS

Of the 1443 patients with diagnosis of keloids, 131 patients had childhood-onset keloids. Of these, 106 patients (80.9%) were female, 38.9% of patients had family history of keloids, and 48.9% of patients had allergies or allergy-related conditions (asthma, atopic dermatitis, or allergic rhinitis). Vaccination (47.5%) and chickenpox (19.9%) were the most common triggers. Of vaccinations, BCG was the most common trigger. The majority of keloids from BCG were in female patients (92.9%). The most common location was the chest in male patients (30.0%) and the arm in female patients (41.1%).

CONCLUSION

To our knowledge, this is the largest report in the literature on childhood-onset keloids. There was overall female predominance in childhood-onset keloids, and even more significant female predominance in BCG-induced keloids.

IL-13RA2 downregulation in fibroblasts promotes keloid fibrosis via JAK/STAT6 activation

Keloids are considered the manifestation of a fibroproliferative disease characterized by chronic inflammation that is induced following skin injury. Deciphering the underlying mechanism of keloid formation is essential for improving treatment outcomes. Here, we found that more macrophages were activated toward the M2 subtype in keloid dermis when compared with normal dermis. Western blotting revealed that the level of phosphorylated STAT6 (p-STAT6), a known inducer of M2 polarization, was higher in keloid fibroblasts as opposed to fibroblasts from normal dermis. Moreover, keloid fibrosis was shown to be positively correlated with the level of p-STAT6. Further, we identified downregulation of IL-13RA2, a decoy receptor for IL-13, in keloid fibroblasts compared with fibroblasts from normal dermis. Ectopic expression of IL-13RA2 in keloid fibroblasts resulted in inhibition of STAT6 phosphorylation, cell proliferation, migration, invasion, extracellular matrix secretion, and myofibroblast marker expression, as well as an increase in apoptosis. Consistently, knockdown of IL-13RA2 in normal fibroblasts induced a keloidal status. Furthermore, both in vitro application and intratumoral injection of p-STAT6 inhibitor AS1517499 in a patient-derived xenograft keloid-implantation mouse model resulted in proliferation inhibition and tissue necrosis, apoptosis, and myofibroblast marker reduction. Collectively, this study elucidates the key role of IL-13RA2 in keloid pathology and inspires further translational research of keloid treatment concerning JAK/STAT6 inhibition.

The Role of IL-13 and IL-4 in Adipose Tissue Fibrosis

White adipose tissue (WAT) fibrosis, characterized by an excess of extracellular (ECM) matrix components, is strongly associated with WAT inflammation and dysfunction due to obesity. Interleukin (IL)-13 and IL-4 were recently identified as critical mediators in the pathogenesis of fibrotic diseases. However, their role in WAT fibrosis is still ill-defined. We therefore established an ex vivo WAT organotypic culture system and demonstrated an upregulation of fibrosis-related genes and an increase of α-smooth muscle actin (αSMA) and fibronectin abundance upon dose-dependent stimulation with IL-13/IL-4. These fibrotic effects were lost in WAT lacking il4ra, which encodes for the underlying receptor controlling this process. Adipose tissue macrophages were found to play a key role in mediating IL-13/IL-4 effects in WAT fibrosis as their depletion through clodronate dramatically decreased the fibrotic phenotype. IL-4-induced WAT fibrosis was partly confirmed in mice injected intraperitoneally with IL-4. Furthermore, gene correlation analyses of human WAT samples revealed a strong positive correlation of fibrosis markers with IL-13/IL-4 receptors, whereas IL13 and IL4 correlations failed to confirm this association. In conclusion, IL-13 and IL-4 can induce WAT fibrosis ex vivo and partly in vivo, but their role in human WAT remains to be further elucidated.

The Exciting Future for Scleroderma

Emerging evidence shows that a complex interplay between cells and mediators and extracellular matrix factors may underlie the development and persistence of fibrosis in systemic sclerosis. Similar processes may determine vasculopathy. This article reviews recent progress in understanding how fibrosis becomes profibrotic and how the immune system, vascular, and mesenchymal compartment affect disease development. Early phase trials are informing about pathogenic mechanisms in vivo and reverse translation for observational and randomized trials is allowing hypotheses to be developed and tested. In addition to repurposing already available drugs, these studies are paving the way for the next generation of targeted therapeutics.

An Updated Review of Hypertrophic Scarring

Hypertrophic scarring (HTS) is an aberrant form of wound healing that is associated with excessive deposition of extracellular matrix and connective tissue at the site of injury. In this review article, we provide an overview of normal (acute) wound healing phases (hemostasis, inflammation, proliferation, and remodeling). We next discuss the dysregulated and/or impaired mechanisms in wound healing phases that are associated with HTS development. We next discuss the animal models of HTS and their limitations, and review the current and emerging treatments of HTS.

Comorbidities of Keloid and Hypertrophic Scars Among Participants in UK Biobank

Importance

Keloids and hypertrophic scars (excessive scarring) are relatively understudied disfiguring chronic skin conditions with high treatment resistance.

Objective

To evaluate established comorbidities of excessive scarring in European individuals, with comparisons across ethnic groups, and to identify novel comorbidities via a phenome-wide association study (PheWAS).

Design, Setting, and Participants

This multicenter cross-sectional population-based cohort study used UK Biobank (UKB) data and fitted logistic regression models for testing associations between excessive scarring and a variety of outcomes, including previously studied comorbidities and 1518 systematically defined disease categories. Additional modeling was performed within subgroups of participants defined by self-reported ethnicity (as defined in UK Biobank). Of 502 701 UKB participants, analyses were restricted to 230078 individuals with linked primary care records.

Exposures

Keloid or hypertrophic scar diagnoses.

Main Outcomes and Measures

Previously studied disease associations (hypertension, uterine leiomyoma, vitamin D deficiency, atopic eczema) and phenotypes defined in the PheWAS Catalog.

Results

Of the 972 people with excessive scarring, there was a higher proportion of female participants compared with the 229 106 controls (65% vs 55%) and a lower proportion of White ethnicity (86% vs 95%); mean (SD) age of the total cohort was 64 (8) years. Associations were identified with hypertension and atopic eczema in models accounting for age, sex, and ethnicity, and the association with atopic eczema (odds ratio [OR], 1.68; 95% CI, 1.36-2.07; P < .001) remained statistically significant after accounting for additional potential confounders. Fully adjusted analyses within ethnic groups revealed associations with hypertension in Black participants (OR, 2.05; 95% CI, 1.13-3.72; P = .02) and with vitamin D deficiency in Asian participants (OR, 2.24; 95% CI, 1.26-3.97; P = .006). The association with uterine leiomyoma was borderline significant in Black women (OR, 1.93; 95% CI, 1.00-3.71; P = .05), whereas the association with atopic eczema was significant in White participants (OR, 1.68; 95% CI, 1.34-2.12; P < .001) and showed a similar trend in Asian (OR, 2.17; 95% CI, 1.01-4.67; P = .048) and Black participants (OR, 1.89; 95% CI, 0.83-4.28; P = .13). The PheWAS identified 110 significant associations across disease systems; of the nondermatological, musculoskeletal disease and pain symptoms were prominent.

Conclusions and Relevance

This cross-sectional study validated comorbidities of excessive scarring in UKB with comprehensive coverage of health outcomes. It also documented additional phenome-wide associations that will serve as a reference for future studies to investigate common underlying pathophysiologic mechanisms.

The Complexity of the Post-Burn Immune Response: An Overview of the Associated Local and Systemic Complications

Burn injury induces a complex inflammatory response, both locally and systemically, and is not yet completely unravelled and understood. In order to enable the development of accurate treatment options, it is of paramount importance to fully understand post-burn immunology. Research in the last decades describes insights into the prolonged and excessive inflammatory response that could exist after both severe and milder burn trauma and that this response differs from that of none-burn acute trauma. Persistent activity of complement, acute phase proteins and pro- and anti-inflammatory mediators, changes in lymphocyte activity, activation of the stress response and infiltration of immune cells have all been related to post-burn local and systemic pathology. This "narrative" review explores the current state of knowledge, focusing on both the local and systemic immunology post-burn, and further questions how it is linked to the clinical outcome. Moreover, it illustrates the complexity of post-burn immunology and the existing gaps in knowledge on underlying mechanisms of burn pathology.

Subtyping based on immune cell fractions reveal heterogeneity of cardiac fibrosis in end-stage heart failure

Background

A central issue hindering the development of effective anti-fibrosis drugs for heart failure is the unclear interrelationship between fibrosis and the immune cells. This study aims at providing precise subtyping of heart failure based on immune cell fractions, elaborating their differences in fibrotic mechanisms, and proposing a biomarker panel for evaluating intrinsic features of patients' physiological statuses through subtype classification, thereby promoting the precision medicine for cardiac fibrosis.

Methods

We inferred immune cell type abundance of the ventricular samples by a computational method (CIBERSORTx) based on ventricular tissue samples from 103 patients with heart failure, and applied K-means clustering to divide patients into two subtypes based on their immune cell type abundance. We also designed a novel analytic strategy: Large-Scale Functional Score and Association Analysis (LAFSAA), to study fibrotic mechanisms in the two subtypes.

Results

Two subtypes of immune cell fractions: pro-inflammatory and pro-remodeling subtypes, were identified. LAFSAA identified 11 subtype-specific pro-fibrotic functional gene sets as the basis for personalised targeted treatments. Based on feature selection, a 30-gene biomarker panel (ImmunCard30) established for diagnosing patient subtypes achieved high classification performance, with the area under the receiver operator characteristic curve corresponding to 0.954 and 0.803 for the discovery and validation sets, respectively.

Conclusion

Patients with the two subtypes of cardiac immune cell fractions were likely having different fibrotic mechanisms. Patients' subtypes can be predicted based on the ImmunCard30 biomarker panel. We envision that our unique stratification strategy revealed in this study will unravel advance diagnostic techniques for personalised anti-fibrotic therapy.

An updated review of the immunological mechanisms of keloid scars

Keloid is a type of disfiguring pathological scarring unique to human skin. The disorder is characterized by excessive collagen deposition. Immune cell infiltration is a hallmark of both normal and pathological tissue repair. However, the immunopathological mechanisms of keloid remain unclear. Recent studies have uncovered the pivotal role of both innate and adaptive immunity in modulating the aberrant behavior of keloid fibroblasts. Several novel therapeutics attempting to restore regulation of the immune microenvironment have shown variable efficacy. We review the current understanding of keloid immunopathogenesis and highlight the potential roles of immune pathway-specific therapeutics.

IL-13/IL-4 signaling contributes to fibrotic progression of the myeloproliferative neoplasms

Myelofibrosis (MF) is a disease associated with high unmet medical needs because allogeneic stem cell transplantation is not an option for most patients, and JAK inhibitors are generally effective for only 2 to 3 years and do not delay disease progression. MF is characterized by dysplastic megakaryocytic hyperplasia and progression to fulminant disease, which is associated with progressively increasing marrow fibrosis. Despite evidence that the inflammatory milieu in MF contributes to disease progression, the specific factors that promote megakaryocyte growth are poorly understood. Here, we analyzed changes in the cytokine profiles of MF mouse models before and after the development of fibrosis, coupled with the analysis of bone marrow populations using single-cell RNA sequencing. We found high interleukin 13 (IL-13) levels in the bone marrow of MF mice. IL-13 promoted the growth of mutant megakaryocytes and induced surface expression of transforming growth factor β and collagen biosynthesis. Similarly, analysis of samples from patients with MF revealed elevated levels of IL-13 in the plasma and increased IL-13 receptor expression in marrow megakaryocytes. In vivo, IL-13 overexpression promoted disease progression, whereas reducing IL-13/IL-4 signaling reduced several features of the disease, including fibrosis. Finally, we observed an increase in the number of marrow T cells and mast cells, which are known sources of IL-13. Together, our data demonstrate that IL-13 is involved in disease progression in MF and that inhibition of the IL-13/IL-4 signaling pathway might serve as a novel therapeutic target to treat MF.

Co-expression of fibrotic genes in inflammatory bowel disease; A localized event?

Introduction

Extracellular matrix turnover, a ubiquitous dynamic biological process, can be diverted to fibrosis. The latter can affect the intestine as a serious complication of Inflammatory Bowel Diseases (IBD) and is resistant to current pharmacological interventions. It embosses the need for out-of-the-box approaches to identify and target molecular mechanisms of fibrosis.

Methods and results

In this study, a novel mRNA sequencing dataset of 22 pairs of intestinal biopsies from the terminal ileum (TI) and the sigmoid of 7 patients with Crohn's disease, 6 with ulcerative colitis and 9 control individuals (CI) served as a validation cohort of a core fibrotic transcriptomic signature (FIBSig), This signature, which was identified in publicly available data (839 samples from patients and healthy individuals) of 5 fibrotic disorders affecting different organs (GI tract, lung, skin, liver, kidney), encompasses 241 genes and the functional pathways which derive from their interactome. These genes were used in further bioinformatics co-expression analyses to elucidate the site-specific molecular background of intestinal fibrosis highlighting their involvement, particularly in the terminal ileum. We also confirmed different transcriptomic profiles of the sigmoid and terminal ileum in our validation cohort. Combining the results of these analyses we highlight 21 core hub genes within a larger single co-expression module, highly enriched in the terminal ileum of CD patients. Further pathway analysis revealed known and novel inflammation-regulated, fibrogenic pathways operating in the TI, such as IL-13 signaling and pyroptosis, respectively.

Discussion

These findings provide a rationale for the increased incidence of fibrosis at the terminal ileum of CD patients and highlight operating pathways in intestinal fibrosis for future evaluation with mechanistic and translational studies.