Search

Systemic sclerosis (SSc) is characterized by dermal fibrosis with a female predominance, suggesting a hormonal influence. Patients with SSc have elevated interleukin (IL)-6 levels, and post-menopausal women and older men also have high estradiol (E2) levels. In the skin, IL-6 increases the enzymatic activity of aromatase, thereby amplifying the conversion of testosterone to E2. Therefore, we hypothesized that an interplay between E2 and IL-6 contributes to dermal fibrosis. We used primary dermal fibroblasts from healthy donors and patients with diffuse cutaneous (dc)SSc, and healthy donor skin tissues stimulated with recombinant IL-6 and its soluble receptor (sIL-6R) or E2. Primary human dermal fibroblasts and tissues from healthy donors stimulated with IL-6+sIL-6R produced E2, while E2-stimulated dermal tissues and fibroblasts produced IL-6. Primary dermal fibroblasts from healthy donors treated with IL-6+sIL-6R and the aromatase inhibitor anastrozole (ANA) and dcSSc fibroblasts treated with ANA produced less fibronectin (FN), type III collagen A1 (Col IIIA1), and type V collagen A1 (Col VA1). Finally, dcSSc dermal fibroblasts treated with the estrogen receptor inhibitor fulvestrant also generated less FN, Col IIIA1, and Col VA1. Our data show that IL-6 exerts its pro-fibrotic influence in human skin in part through E2 and establish a positive feedback loop between E2 and IL-6.

Systemic sclerosis (SSc) is characterized by dermal fibrosis with a female predominance, suggesting a hormonal influence. Patients with SSc have elevated interleukin (IL)-6 levels, and post-menopausal women and older men also have high estradiol (E2) levels. In the skin, IL-6 increases the enzymatic activity of aromatase, thereby amplifying the conversion of testosterone to E2. Therefore, we hypothesized that an interplay between E2 and IL-6 contributes to dermal fibrosis. We used primary dermal fibroblasts from healthy donors and patients with diffuse cutaneous (dc)SSc, and healthy donor skin tissues stimulated with recombinant IL-6 and its soluble receptor (sIL-6R) or E2. Primary human dermal fibroblasts and tissues from healthy donors stimulated with IL-6+sIL-6R produced E2, while E2-stimulated dermal tissues and fibroblasts produced IL-6. Primary dermal fibroblasts from healthy donors treated with IL-6+sIL-6R and the aromatase inhibitor anastrozole (ANA) and dcSSc fibroblasts treated with ANA produced less fibronectin (FN), type III collagen A1 (Col IIIA1), and type V collagen A1 (Col VA1). Finally, dcSSc dermal fibroblasts treated with the estrogen receptor inhibitor fulvestrant also generated less FN, Col IIIA1, and Col VA1. Our data show that IL-6 exerts its pro-fibrotic influence in human skin in part through E2 and establish a positive feedback loop between E2 and IL-6. [ABSTRACT FROM AUTHOR]

Abstract Dupuytren’s contracture, a superficial dermal fibrosis, causes flexion contracture of the affected finger, impairing hand function. Specific single-nucleotide polymorphisms within genes in the Wnt signalling pathway are associated with the disease. However, the precise role of Wnt signalling dysregulation in the onset and progression of Dupuytren’s contracture remains unclear. Here, using a fibrosis mouse model and clinical samples of human Dupuytren’s contractures, we demonstrate that the activation of Wnt/β-catenin signalling in Tppp3-positive cells in the dermis of the paw is associated with the development of fibrosis. Fibrosis development and progression via Wnt/β-catenin signalling are closely related to stromal cell–macrophage interactions, and Wnt/β-catenin signalling activation in Tppp3-positive stromal cells causes M2 macrophage infiltration via chemokine Cxcl14, resulting in the formation of a TGF-β-expressing fibrotic niche. Inhibition of Cxcl14 mitigates fibrosis by decreasing macrophage infiltration. These findings suggest that Cxcl14-mediated stromal cell–macrophage interaction is a promising therapeutic target for Wnt/β-catenin-induced fibrosis.

Objective: Erythropoietin‐producing hepatocellular (Eph)/Ephrin cell–cell signaling is emerging as a key player in tissue fibrogenesis. The aim of this study was to test the hypothesis that the receptor tyrosine kinase EphB2 mediates dermal fibrosis in systemic sclerosis (SSc). Methods: We assessed normal and SSc human skin biopsies for EphB2 expression. The in vivo role of EphB2 in skin fibrosis was investigated by subjecting EphB2‐knockout mice to both bleomycin‐induced and tight skin (Tsk1/+) genetic mouse models of skin fibrosis. EphB2 kinase‐dead and overactive point mutant mice were used to evaluate the role of EphB2 forward signaling in bleomycin‐induced dermal fibrosis. In vitro studies were performed on dermal fibroblasts from patients with SSc and healthy controls, which was followed by in vivo analysis of fibroblast‐specific Ephb2‐deficient mice. Results: Expression of EphB2 is up‐regulated in SSc skin tissue and explanted SSc dermal fibroblasts compared with healthy controls. EphB2 expression is elevated in two animal models of dermal fibrosis. In mice, EphB2 drives dermal fibrosis in both the bleomycin and the Tsk1/+ models of skin fibrosis. EphB2 forward signaling is a critical mediator of dermal fibrosis. Transforming growth factor‐β (TGF‐β) cytokines up‐regulate EphB2 in dermal fibroblasts via noncanonical TGF‐β/mother against decapentaplegic signaling, and silencing EPHB2 in human dermal fibroblasts is sufficient to dampen TGF‐β–induced fibroblast‐to‐myofibroblast differentiation. Moreover, mice with fibroblast‐specific deletion of EphB2 showed impaired fibroblast‐to‐myofibroblast differentiation and reduced skin fibrosis upon bleomycin challenge. Conclusion: Our data implicate TGF‐β regulation of EphB2 overexpression and kinase‐mediated forward signaling in the development of dermal fibrosis in SSc. EphB2 thus represents a potential new therapeutic target for SSc. [ABSTRACT FROM AUTHOR]

Objectives: We previously revealed the role of tanshinone IIA (TAN IIA) on endothelial cells and the impact of TAN IIA on the endothelial‐to‐mesenchymal transition in systemic sclerosis (SSc). In this study, we sought to further determine whether TAN IIA can directly act on the skin fibroblasts of scleroderma and look into its underlying anti‐fibrotic mechanisms. Methods: Bleomycin was used to establish the SSc mouse model. After TAN IIA treatment, dermal thickness, type I collagen and hydroxyproline content were measured. Primary fibroblasts were acquired from SSc patients and cultured in vitro, and the effects of TAN IIA on proliferation, apoptosis and the cell cycle of fibroblasts were detected. Results: In a bleomycin‐induced SSc model, we discovered that TAN IIA significantly improved skin thickness and collagen deposition, demonstrating a potent anti‐fibrotic action. TAN IIA inhibits the proliferation of skin fibroblasts derived from SSc patients by causing G2/M cell cycle arrest and promoting apoptosis. Additionally, TAN IIA downregulated extracellular matrix gene transcription and collagen protein expression in skin fibroblasts in a dose‐gradient‐dependent manner. Furthermore, we showed how TAN IIA can reduce the activation of the transforming growth factor‐β (TGF‐β)/Smad and mitogen‐activated protein kinase (MAPK)/extracellular signal‐regulated kinase (ERK) pathways, which are important factors in SSc. Conclusions: In summary, these data suggest that TAN IIA can reduce SSc‐related skin fibrosis by modulating the TGF‐β/Smad and MAPK/ERK signalling pathways. More importantly, our results imply that TAN IIA can directly act on the skin fibroblasts of SSc, therefore, inhibiting fibrosis. [ABSTRACT FROM AUTHOR]

Abstract Background Systemic sclerosis is a rheumatoid disease best known for its fibrotic skin manifestations called scleroderma. Alternatively activated (M2-type) macrophages are normally involved in the resolution of inflammation and wound healing but also in fibrosing diseases such as scleroderma. TRPA1 is a non-selective cation channel, activation of which causes pain and neurogenic inflammation. In the present study, we investigated the role of TRPA1 in bleomycin-induced skin fibrosis mimicking scleroderma. Methods Wild type and TRPA1-deficient mice were challenged with intradermal bleomycin injections to induce a scleroderma-mimicking disease. Macrophages were investigated in vitro to evaluate the underlying mechanisms. Results Bleomycin induced dermal thickening and collagen accumulation in wild type mice and that was significantly attenuated in TRPA1-deficient animals. Accordingly, the expression of collagens 1A1, 1A2, and 3A1 as well as pro-fibrotic factors TGF-beta, CTGF, fibronectin-1 and YKL-40, and M2 macrophage markers Arg1 and MRC1 were lower in TRPA1-deficient than wild type mice. Furthermore, bleomycin was discovered to significantly enhance M2-marker expression particularly in the presence of IL-4 in wild type macrophages in vitro, but not in macrophages harvested from TRPA1-deficient mice. IL-4-induced PPARγ-expression in macrophages was increased by bleomycin, providing a possible mechanism behind the phenomenon. Conclusions In conclusion, the results indicate that interfering TRPA1 attenuates fibrotic and inflammatory responses in bleomycin-induced scleroderma. Therefore, TRPA1-blocking treatment could potentially alleviate M2 macrophage driven diseases like systemic sclerosis and scleroderma.

In the skin, estradiol (E2) promotes profibrotic and proinflammatory cytokines, contributing to extracellular matrix (ECM) deposition. However, the magnitude of the response differs. Using the human skin organ culture model, we evaluated donor characteristics and correlations that contribute to E2-induced interleukin-6 (IL-6), transforming growth factor beta 1 and 2 (TGFB1 and TGFB2), collagen IA2 (Col IA2), collagen IIIA1 (Col IIIA1), and fibronectin (FN) expressions. In vehicle- and E2-treated dermal skin tissue transcripts, we confirm differences in the magnitude; however, there were positive correlations between profibrotic mediators and ECM components 48 h after E2 treatment. Also, positive correlations exist between baseline and E2-induced TGFB1, IL-6, Col IIIA1, and FN transcripts. Since estrogen receptor alpha (ERA) can propagate E2′s signal, we measured and detected differences in its baseline and fold change transcript levels, with a significant decline in baseline levels 48 h after incubation and an increase 48 h after E2 treatment. There was a trend to higher transcript levels in African American donors 24 h earlier. Finally, E2-induced ERA transcript levels negatively correlated with its own baseline levels and positively correlated with FN, TGFB1, and Col IA2 transcript levels. Therefore, our data suggest ERA, E2 exposure time, and race/ethnicity contribute to E2-induced dermal fibrosis.

In the skin, estradiol (E2) promotes profibrotic and proinflammatory cytokines, contributing to extracellular matrix (ECM) deposition. However, the magnitude of the response differs. Using the human skin organ culture model, we evaluated donor characteristics and correlations that contribute to E2-induced interleukin-6 ( IL-6 ), transforming growth factor beta 1 and 2 ( TGFB1 and TGFB2 ), collagen IA2 ( Col IA2 ), collagen IIIA1 ( Col IIIA1 ), and fibronectin ( FN ) expressions. In vehicle- and E2-treated dermal skin tissue transcripts, we confirm differences in the magnitude; however, there were positive correlations between profibrotic mediators and ECM components 48 h after E2 treatment. Also, positive correlations exist between baseline and E2-induced TGFB1 , IL-6 , Col IIIA1 , and FN transcripts. Since estrogen receptor alpha (ERA) can propagate E2's signal, we measured and detected differences in its baseline and fold change transcript levels, with a significant decline in baseline levels 48 h after incubation and an increase 48 h after E2 treatment. There was a trend to higher transcript levels in African American donors 24 h earlier. Finally, E2-induced ERA transcript levels negatively correlated with its own baseline levels and positively correlated with FN , TGFB1 , and Col IA2 transcript levels. Therefore, our data suggest ERA, E2 exposure time, and race/ethnicity contribute to E2-induced dermal fibrosis.

In the original publication [...]

Considerable evidence accumulated over the past decade supports that telocytes (TCs)/CD34+ stromal cells represent an exclusive type of interstitial cells identifiable by transmission electron microscopy (TEM) or immunohistochemistry in various organs of the human body, including the skin. By means of their characteristic cellular extensions (telopodes), dermal TCs are arranged in networks intermingled with a multitude of neighboring cells and, hence, they are thought to contribute to skin homeostasis through both intercellular contacts and releasing extracellular vesicles. In this context, fibrotic skin lesions from patients with systemic sclerosis (SSc, scleroderma) appear to be characterized by a disruption of the dermal network of TCs, which has been ascribed to either cell degenerative processes or possible transformation into profibrotic myofibroblasts. In the present study, we utilized the well-established mouse model of bleomycin-induced scleroderma to gain further insights into the TC alterations found in cutaneous fibrosis. CD34 immunofluorescence revealed a severe impairment in the dermal network of TCs/CD34+ stromal cells in bleomycin-treated mice. CD31/CD34 double immunofluorescence confirmed that CD31−/CD34+ TC counts were greatly reduced in the skin of bleomycin-treated mice compared with control mice. Ultrastructural signs of TC injury were detected in the skin of bleomycin-treated mice by TEM. The analyses of skin samples from mice treated with bleomycin for different times by either TEM or double immunostaining and immunoblotting for the CD34/α-SMA antigens collectively suggested that, although a few TCs may transition to α-SMA+ myofibroblasts in the early disease stage, most of these cells rather undergo degeneration, and then are lost. Taken together, our data demonstrate that TC changes in the skin of bleomycin-treated mice mimic very closely those observed in human SSc skin, which makes this experimental model a suitable tool to (i) unravel the pathological mechanisms underlying TC damage and (ii) clarify the possible contribution of the TC loss to the development/progression of dermal fibrosis. In perspective, these findings may have important implications in the field of skin regenerative medicine.

Abstract Background Both TGFβ and estradiol (E2), a form of estrogen, are pro-fibrotic in the skin. In the connective tissue disease, systemic sclerosis (SSc), both TGFβ and E2 are likely pathogenic. Yet the regulation of TGFβ in E2-induced dermal fibrosis remains ill-defined. Elucidating those regulatory mechanisms will improve the understanding of fibrotic disease pathogenesis and set the stage for developing potential therapeutics. Using E2-stimulated primary human dermal fibroblasts in vitro and human skin tissue ex vivo, we identified the important regulatory proteins for TGFβ and investigated the extracellular matrix (ECM) components that are directly stimulated by E2-induced TGFβ signaling. Methods We used primary human dermal fibroblasts in vitro and human skin tissue ex vivo stimulated with E2 or vehicle (ethanol) to measure TGFβ1 and TGFβ2 levels using quantitative PCR (qPCR). To identify the necessary cell signaling proteins in E2-induced TGFβ1 and TGFβ2 transcription, human dermal fibroblasts were pre-treated with an inhibitor of the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathway, U0126. Finally, human skin tissue ex vivo was pre-treated with SB-431542, a TGFβ receptor inhibitor, and ICI 182,780, an estrogen receptor α (ERα) inhibitor, to establish the effects of TGFβ and ERα signaling on E2-induced collagen 22A1 (Col22A1) transcription. Results We found that expression of TGFβ1, TGFβ2, and Col22A1, a TGFβ-responsive gene, is induced in response to E2 stimulation. Mechanistically, Col22A1 induction was blocked by SB-431542 and ICI 182,780 despite E2 stimulation. Additionally, inhibiting E2-induced ERK/MAPK activation and early growth response 1 (EGR1) transcription prevents the E2-induced increase in TGFβ1 and TGFβ2 transcription and translation. Conclusions We conclude that E2-induced dermal fibrosis occurs in part through induction of TGFβ1, 2, and Col22A1, which is regulated through EGR1 and the MAPK pathway. Thus, blocking estrogen signaling and/or production may be a novel therapeutic option in pro-fibrotic diseases.

Our previous study demonstrated that heat shock protein 90 (Hsp90) is overexpressed in the involved skin of patients with systemic sclerosis (SSc) and in experimental dermal fibrosis. Pharmacological inhibition of Hsp90 prevented the stimulatory effects of transforming growth factor-beta on collagen synthesis and the development of dermal fibrosis in three preclinical models of SSc. In the next step of the preclinical analysis, herein, we aimed to evaluate the efficacy of an Hsp90 inhibitor, 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG), in the treatment of established experimental dermal fibrosis induced by bleomycin. Treatment with 17-DMAG demonstrated potent antifibrotic and anti-inflammatory properties: it decreased dermal thickening, collagen content, myofibroblast count, expression of transforming growth factor beta receptors, and pSmad3-positive cell counts, as well as leukocyte infiltration and systemic levels of crucial cytokines/chemokines involved in the pathogenesis of SSc, compared to vehicle-treated mice. 17-DMAG effectively prevented further progression and may induce regression of established bleomycin-induced dermal fibrosis to an extent comparable to nintedanib. These findings provide further evidence of the vital role of Hsp90 in the pathophysiology of SSc and characterize it as a potential target for the treatment of fibrosis with translational implications due to the availability of several Hsp90 inhibitors in clinical trials for other indications.

Abstract Progressive fibrosis of the dermal tissues is a challenging complication of radiotherapy whose underlying mechanism is not fully understood, and there are few available treatments. The canonical Wnt/β-catenin signaling pathway plays an important role in fibrosis as well as in the epithelial-to-mesenchymal transition (EMT). We investigated whether inhibition of Wnt/β-catenin signaling with sLRP6E1E2, a molecule that binds to extracellular Wnt ligands, ameliorated radiation-induced fibrosis both in vitro and in vivo. Radiation with a single dose of 2 Gy not only facilitated fibrosis in cultured human dermal fibroblasts via activation of the Wnt/β-catenin pathway but also initiated EMT in cultured keratinocytes, developing collagen-producing mesenchymal cells. sLRP6E1E2-expressing adenovirus treatment exerted anti-fibrotic activity in irradiated cultured dermal fibroblasts and keratinocytes. In a mouse model, a single fraction of 15 Gy was delivered to the dorsal skins of 36 mice randomized into three groups: those receiving PBS, those receiving control adenovirus, and those receiving decoy Wnt receptor-expressing adenovirus (dE1-k35/sLRP6E1E2). The mice were observed for 16 weeks, and excessive deposition of type I collagen was suppressed by sLRP6E1E2-expressing adenovirus treatment. These results demonstrate that the modulation of the Wnt/β-catenin pathway has the potential to decrease the severity of radiation-induced dermal fibrosis.

Raised dermal scars including hypertrophic, and keloid scars as well as scalp‐associated fibrosing Folliculitis Keloidalis Nuchae (FKN) are a group of fibrotic raised dermal lesions that mostly occur following cutaneous injury. They are characterized by increased extracellular matrix (ECM) deposition, primarily excessive collagen type 1 production by hyperproliferative fibroblasts. The extent of ECM deposition is thought to be proportional to the severity of local skin inflammation leading to excessive fibrosis of the dermis. Due to a lack of suitable study models, therapy for raised dermal scars remains ill‐defined. Immune cells and their associated markers have been strongly associated with dermal fibrosis. Therefore, modulation of the immune system and use of anti‐inflammatory cytokines are of potential interest in the management of dermal fibrosis. In this review, we will discuss the importance of immune factors in the pathogenesis of raised dermal scarring. The aim here is to provide an up‐to‐date comprehensive review of the literature, from PubMed, Scopus, and other relevant search engines in order to describe the known immunological factors associated with raised dermal scarring. The importance of immune cells including mast cells, macrophages, lymphocytes, and relevant molecules such as cytokines, chemokines, and growth factors, antibodies, transcription factors, and other immune‐associated molecules as well as tissue lymphoid aggregates identified within raised dermal scars will be presented. A growing body of evidence points to a shift from proinflammatory Th1 response to regulatory/anti‐inflammatory Th2 response being associated with the development of fibrogenesis in raised dermal scarring. In summary, a better understanding of immune cells and associated molecular markers in dermal fibrosis will likely enable future development of potential immune‐modulated therapeutic, diagnostic, and theranostic targets in raised dermal scarring. [ABSTRACT FROM AUTHOR]

Abstract Background Fibrotic diseases are characterized by tissue overgrowth, hardening, and/or scarring because of the excessive production, deposition, and contraction of the extracellular matrix (ECM). However, the detailed mechanisms underlying these disorders remain unclear. It was recently reported that α2-antiplasmin (α2AP) is elevated in fibrotic tissue and that it is associated with the development of fibrosis. In the present study, we examined the mechanism underlying the production of α2AP on the development of fibrosis. Methods To clarify the mechanism underlying the production of α2AP on the development of fibrosis, we focused on high-mobility group box 1 (HMGB1), which is associated with the development of fibrosis. The mouse model of bleomycin-induced fibrosis was used to evaluate the production of α2AP on the development of fibrosis. Results We found that HMGB1 induced the production of α2AP through receptor for advanced glycation end products (RAGE) in fibroblasts. Next, we showed that macrophage reduction by a macrophage-depleting agent, clodronate, attenuated the progression of fibrosis and the production of α2AP and HMGB1 in the bleomycin-induced mice. We also showed that IL-4-stimulated alternatively activated macrophages induced the production of HMGB1, that IL-4-stimulated alternatively activated macrophage conditioned media (CM) induced pro-fibrotic changes and α2AP production, and that the inhibition of HMGB1 and RAGE attenuated these effects in fibroblasts. Furthermore, the blockade of IL-4 signaling by IL-4Rα neutralizing antibodies attenuated the progression of fibrosis and the production of α2AP and HMGB1 in the bleomycin-induced mice. Conclusion These findings suggest that alternatively activated macrophage-derived HMGB1 induced the production of α2AP through RAGE and that these effects are associated with the development of fibrosis. Our findings may provide a clinical strategy for managing fibrotic disorders.

Background: Hypertrophic scars (HTS) result from injury to the skin and represent a clinical burden with limited treatment options. Previously, we demonstrated that statin drugs could attenuate HTS formation, but convenient topical delivery and retention of these drugs at the wound site remains a challenge. Aims: Here, we aimed to develop a topical cream formulation that can deliver statin drugs simply and conveniently to reduce scar hypertrophy. Methods: We formulated creams containing 10% pravastatin, 2% simvastatin, and 10% simvastatin. We tested these creams for their ability to reduce scar hypertrophy and attenuate dermal fibrosis in a clinically relevant HTS wound model performed in rabbit ear skin. We also monitored trans‐epidermal water loss (TEWL) over the course of wound healing in order to understand the effects of statin treatment on epidermal barrier recovery. Results: Of the three creams formulated, only application of 10% simvastatin cream significantly attenuated hypertrophy of resultant scars compared with vehicle cream application. Application of 10% simvastatin cream resulted in a decrease in macrophage and myofibroblast density at post‐operative day 28 (POD28) harvest. Application of 10% simvastatin cream resulted in visible symptoms of dryness and increased TEWL at POD28, but subsequent withdrawal of statin cream treatment resulted in rapid alleviation of dryness and decrease in TEWL back to normal levels. Conclusions: Our data demonstrate that topical administration of 10% simvastatin cream antagonizes dermal fibrosis and reduces hypertrophy in an HTS model, and withdrawal of the cream enables recovery of epidermal barrier and resolution of skin dryness. [ABSTRACT FROM AUTHOR]

Fibrosis of the skin and internal organs is a hallmark of systemic sclerosis (SSc). Although the pathogenesis of SSc is poorly understood, increasing evidence suggests that interleukins (IL)-4 and - 13 contribute to the pathogenesis of skin fibrosis by promoting collagen production and myofibroblast differentiation. Signal transducers and activators of transcription 6 (STAT6) is one of the most important downstream transcription factors activated by both IL-4 and IL-13. However, it is not completely understood whether STAT6 plays a role during the pathogenesis of skin fibrosis in SSc. In this study, we observed increased STAT6 phosphorylation in fibrotic skin samples collected from SSc patients as well as bleomycin-injected murine mice. Knockout of Stat6 in mice significantly (1) suppressed the expression of fibrotic cytokines including Il13, Il17, Il22, Ccl2, and the alternatively activated macrophage marker Cd206; (2) reduced the production of collagen and fibronectin, and (3) attenuated late-stage skin fibrosis and inflammation induced by bleomycin. Consistently, mice treated with STAT6 inhibitor AS1517499 also attenuated skin fibrosis on day 28. In addition, a co-culture experiment demonstrated that skin epithelial cells with STAT6 knockdown had reduced cytokine expression in response to IL-4/IL-13, and subsequently attenuated fibrotic protein expression in skin fibroblasts. On the other side, STAT6 depletion in skin fibroblasts attenuated IL-4/IL-13-induced cytokine and fibrotic marker expression, and reduced CXCL2 expression in co-cultured keratinocytes. In summary, our study highlighted an important yet not fully understood role of STAT6 in skin fibrosis by driving innate inflammation and differentiation of alternatively activated macrophages in response to injury., (© 2023 Federation of American Societies for Experimental Biology.)

Excessive fibrosis following surgical procedures is a challenging condition with serious consequences and no effective preventive or therapeutic option. Our group has previously shown the anti-fibrotic effect of kynurenic acid (KynA) in vitro and as topical cream formulations or nanofiber dressings in open wounds. Here, we hypothesized that the implantation of a controlled release drug delivery system loaded with KynA in a wound bed can prevent fibrosis in a closed wound. Poly (lactic-co-glycolic acid) (PLGA), and a diblock copolymer, methoxy polyethylene glycol-block-poly (D, L-lactide) (MePEG-b-PDLLA), were used for the fabrication of microspheres which were evaluated for their characteristics, encapsulation efficiency, in vitro release profile, and in vivo efficacy for reduction of fibrosis. The optimized formulation exhibited high encapsulation efficiency (>80%), low initial burst release (~10%), and a delayed, gradual release of KynA. In vivo evaluation of the fabricated microspheres in the PVA model of wound healing revealed that KynA microspheres effectively reduced collagen deposition inside and around PVA sponges and α-smooth muscle actin expression after 66 days. Our results showed that KynA can be efficiently encapsulated in PLGA microspheres and its controlled release in vivo reduces fibrotic tissue formation, suggesting a novel therapeutic option for the prevention or treatment of post-surgical fibrosis.

Objective(s): This study aims to investigate the pathogenicity and possible mechanisms of S100A9 function in mice models of scleroderma. Materials and Methods: The content of S100A9 in the skin tissues of mice with scleroderma was determined. Different concentrations of bleomycin (BLM) and S100A9 were subcutaneously injected into the backs of mice simultaneously, and then pathological changes in the skin of these mice were monitored. Specifically, the levels of inflammatory cytokines and alpha smooth muscle actin (α-SMA), the activation of extracellular regulated kinase 1/2 (ERK1/2), mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) pathways, and the expression of the receptor for advanced glycation end-product (RAGE) in the skin were determined. Results: The content of S100A9 in the skin tissues of mice with scleroderma was determined. Different concentrations of BLM and S100A9 were subcutaneously injected into the backs of mice simultaneously, and then pathological changes in the skin of these mice were monitored. Specifically, the levels of inflammatory cytokines and alpha smooth muscle actin (α-SMA), the activation of extracellular regulated kinase 1/2 (ERK1/2) mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) pathways, and the expression of the receptor for advanced glycation end-product (RAGE) in the skin were determined. Conclusion: S100A9 aggravates dermal fibrosis in BLM-induced scleroderma (BIS ) mice, and its mechanisms might be mediated by RAGE, ERK1/2, and NF-κB pathway.

Objective: One of the histologic characteristics of systemic sclerosis (SSc) is an increased number of dermal myofibroblasts, and transforming growth factor β (TGFβ) plays a crucial role in the promotion of myofibroblast differentiation from fibroblasts, leading to dermal fibrosis. This study was undertaken to 1) examine whether inhibition of the cell cycle with a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor suppresses the proliferation of fibroblasts and their differentiation into myofibroblasts, and 2) assess the therapeutic effects of a CDK4/6 inhibitor, administered as monotherapy or in combination with a TGFβ receptor (TGFβR) inhibitor, on dermal fibrosis in murine models of SSc., Methods: Fibroblasts obtained from the skin of patients with SSc were cultured in the presence or absence of TGFβ. The effects of palbociclib, a CDK4/6 inhibitor, on fibroblast proliferation and TGFβ-induced differentiation into myofibroblasts were examined using bromodeoxyuridine uptake assays as well as immunofluorescence and immunoblotting analyses. Murine models of HOCl- and bleomycin-induced dermal fibrosis were used to study the effect of a CDK4/6 inhibitor on dermal fibrosis, with the CDK4/6 inhibitor treatment administered as monotherapy or in combination with galunisertib, a TGFβR inhibitor., Results: Addition of a CDK4/6 inhibitor to the cell cultures suppressed the proliferation of human dermal SSc fibroblasts and their TGFβ-induced differentiation into myofibroblasts, without inhibiting canonical and noncanonical TGFβ signals. In murine models of dermal fibrosis, treatment of mice with a CDK4/6 inhibitor decreased dermal thickness and collagen content, as well as dermal fibroblast proliferation and the numbers of myofibroblasts. Combination therapy with the CDK4/6 inhibitor and TGFβR inhibitor resulted in additive antifibrotic effects. Mechanistically, the CDK4/6 inhibitor suppressed the expression of cellular communication network 2 and cadherin-11, which are proteins that have important roles in the development and progression of fibrosis., Conclusion: Results of this study demonstrate the therapeutic effect of a CDK4/6 inhibitor on dermal fibrosis when administered as monotherapy or in combination with a TGFβR inhibitor. CDK4/6 inhibitors, including palbociclib used in the present study, may represent novel agents for the treatment of SSc, which, if used in combination with a TGFβR inhibitor, might result in increased efficacy., (© 2021 American College of Rheumatology.)

Fibrosis of the skin and internal organs is a hallmark of systemic sclerosis (SSc). Although the pathogenesis of SSc is poorly understood, increasing evidence suggests that interleukins (IL)-4 and - 13 contribute to the pathogenesis of skin fibrosis by promoting collagen production and myofibroblast differentiation. Signal transducers and activators of transcription 6 (STAT6) is one of the most important downstream transcription factors activated by both IL-4 and IL-13. However, it is not completely understood whether STAT6 plays a role during the pathogenesis of skin fibrosis in SSc. In this study, we observed increased STAT6 phosphorylation in fibrotic skin samples collected from SSc patients as well as bleomycin-injected murine mice. Knockout of Stat6 in mice significantly (1) suppressed the expression of fibrotic cytokines including Il13, Il17, Il22, Ccl2, and the alternatively activated macrophage marker Cd206; (2) reduced the production of collagen and fibronectin, and (3) attenuated late-stage skin fibrosis and inflammation induced by bleomycin. Consistently, mice treated with STAT6 inhibitor AS1517499 also attenuated skin fibrosis on day 28. In addition, a co-culture experiment demonstrated that skin epithelial cells with STAT6 knockdown had reduced cytokine expression in response to IL-4/IL-13, and subsequently attenuated fibrotic protein expression in skin fibroblasts. On the other side, STAT6 depletion in skin fibroblasts attenuated IL-4/IL-13- induced cytokine and fibrotic marker expression, and reduced CXCL2 expression in co-cultured keratinocytes. In summary, our study highlighted an important yet not fully understood role of STAT6 in skin fibrosis by driving innate inflammation and differentiation of alternatively activated macrophages in response to injury. [ABSTRACT FROM AUTHOR]

Objective: To determine contributions and functions of autoantibodies (Abs) directed to the angiotensin receptor type 1 (AT1R), which are suggested to be involved in the pathogenesis of AT1R Abs-related diseases such as systemic sclerosis (SSc)., Methods: C57BL/6J mice were immunised with membrane-embedded human AT1R or empty membrane as control. Mice deficient for CD4 + or CD8 + T cells and B cells were immunised with membrane-embedded AT1R or an AT1R peptide proposed to be a dominant T cell epitope. A monoclonal (m)AT1R Ab was generated by hybridoma technique and transferred into C57BL/6J and AT1Ra/b knockout mice. The induced phenotype was examined by histology, immunohistochemistry, immunofluorescence, apoptosis assay and ELISA. In vitro, Abs responses towards AT1R were measured in cells of different origins and species., Results: AT1R-immunised mice developed perivascular skin and lung inflammation, lymphocytic alveolitis, weak lung endothelial apoptosis and skin fibrosis accompanied by Smad2/3 signalling, not present in controls or mice deficient for CD4 + T and B cells. The AT1R peptide 149-172 provoked lung inflammation. Application of the mAT1R Ab induced skin and lung inflammation, not observed in AT1Ra/b knockout mice. In vitro, AT1R Abs activated rat cardiomyocytes and human monocytes, enhanced angiotensin II-mediated AT1R activation in AT1R-transfected HEK293 cells via AT1R binding and mAT1R Ab-activated monocytes mediated the induction of profibrotic markers in dermal fibroblasts., Conclusion: Our immunisation strategy successfully induced AT1R Abs, contributing to inflammation and, possibly, to fibrosis via activation of AT1R. Therefore, AT1R Abs are valuable targets for future therapies of SSc and other AT1R Ab-related diseases., Competing Interests: Competing interests: HH is the owner and GR is an advisor of the company CellTrend GmbH, which produced the ME and the tests for the detection of AT1R Abs. IS and GW are shareholders of Berlin Cures GmbH, where the rat cardiomyocyte assay was performed., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY. Published by BMJ.)