Increased expression of p53 and p21 (Waf1/Cip1) in the lesional skin of bleomycin-induced scleroderma

Effects of Ruxolitinib on fibrosis in preclinical models of systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune fibrotic disorder notably characterized by the production of antinuclear autoantibodies, which have been linked to an excess of apoptotic cells, normally eliminated by a macrophagic efferocytosis. As interferon (IFN) signature and phosphorylation of JAK-STAT proteins are hallmarks of SSc tissues, we tested the hypothesis that a JAK inhibitor, ruxolitinib, targeting the IFN signaling, could improve efferocytosis of IFN-exposed human macrophages in vitro as well as skin and lung fibrosis. In vivo, BLM- and HOCl-induced skin thickness and fibrosis is associated with an increase of caspase-3 positive dermal cells and a significant increase of IFN-stimulated genes expression. In BLM-SSc model, ruxolitinib prevented dermal thickness, fibrosis and significantly decreased the number of cleaved caspase-3 cells in the dermis. Ruxolitinib also improved lung architecture and fibrosis although IFN signature was not entirely decreased by ruxolitinib. In vitro, ruxolitinib improves efferocytosis capacity of human monocyte-differentiated macrophages exposed to IFN-γ or IFN-β. In human fibroblasts derived from lung (HLF) biopsies isolated from patients with idiopathic pulmonary fibrosis, the reduced mRNA expression of typical TGF-β-activated markers by ruxolitinib was associated with a decrease of the phosphorylation of SMAD2 /3 and STAT3. Our finding supports the anti-fibrotic properties of ruxolitinib in a systemic SSc mouse model and in vitro in human lung fibroblasts.

Cytotoxic CD4+ T lymphocytes may induce endothelial cell apoptosis in systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune fibrotic disease whose pathogenesis is poorly understood and lacks effective therapies. We undertook quantitative analyses of T cell infiltrates in the skin of 35 untreated patients with early diffuse SSc and here show that CD4+ cytotoxic T cells and CD8+ T cells contribute prominently to these infiltrates. We also observed an accumulation of apoptotic cells in SSc tissues, suggesting that recurring cell death may contribute to tissue damage and remodeling in this fibrotic disease. HLA-DR-expressing endothelial cells were frequent targets of apoptosis in SSc, consistent with the prominent vasculopathy seen in patients with this disease. A circulating effector population of cytotoxic CD4+ T cells, which exhibited signatures of enhanced metabolic activity, was clonally expanded in patients with systemic sclerosis. These data suggest that cytotoxic T cells may induce the apoptotic death of endothelial and other cells in systemic sclerosis. Cell loss driven by immune cells may be followed by overly exuberant tissue repair processes that lead to fibrosis and tissue dysfunction.

Identification of Biomarkers Related to Systemic Sclerosis With or Without Pulmonary Hypertension Using Co-expression Analysis

Systemic sclerosis (SSc), also known as scleroderma, is an autoimmune disease with multiple system involvement, and pulmonary complications, including pulmonary hypertension (PH), are leading causes of death. This study aimed to develop early biomarkers to distinguish SSc with or without PH from normal population using bioinformatics approaches. The gene expression profile GSE22356, which contains 10 SSc samples with PH, 10 SSc samples without PH, and 10 normal samples, was obtained from the Gene Expression Omnibus database. First, we constructed co-expression networks and identified critical gene modules using the weighted gene co-expression network analysis. Then, functional enrichment analysis of significant modules was performed. Finally, the "real" hub gene was screened out by intramodule analysis and protein-protein interaction networks, and the receiver operating characteristic analysis was conducted. A total of 5046 genes were screened out to construct co-expression networks, and 18 modules were identified. Of these modules, the turquoise module had a strong correlation with SSc only, whereas the midnightblue module showed an obvious positive correlation with SSc with PH. Functional enrichment analysis indicated that the turquoise module was mainly enriched in transcription of DNA template and its regulation and protein ubiquitination and involved in apoptosis and pyrimidine metabolism pathway. The midnightblue module was significantly associated with inflammatory and immune response and pathways in Staphylococcus aureus infection and Chagas disease. The "real" hub genes in the turquoise module were WDR36, POLR1B, and SRSF1, and those in midnightblue were TLR2 and TNFAIP6.

Salvianolic acid B attenuates experimental skin fibrosis of systemic sclerosis

Systemic sclerosis (SSc) is a connective tissue disease characterized mainly by fibrosis of skin and internal organs. Our previous study has shown that salvianolic acid B (SAB), a bioactive component extracted from Salvia miltiorrhiza (SM), was one of the essential ingredients in the traditional Chinese medicine Yiqihuoxue formula, which has been used to treat SSc-related dermal and pulmonary fibrosis. The aim of the present study was to evaluate the effect of SAB on skin fibrosis and explore its underlying anti-fibrotic mechanism. We found that SAB was capable of alleviating skin fibrosis in a bleomycin-induced SSc mouse model, alleviating skin thickness and reducing collagen deposition. in vitro studies indicated that SAB reduced SSc skin fibroblast proliferation and downregulated extracellular matrix gene transcription and collagen protein expression. TGF-β/SMAD and MAPK/ERK pathway activation were also shown to be suppressed in SAB treated fibroblasts. Moreover, RNA-seq revealed that the anti-fibrotic effect of SAB might be related to antioxidant activity, the cell cycle, and the p53 signaling pathway. Taken together, our results suggest that SAB has the ability to alleviate SSc-related skin fibrosis both in vivo and in vitro.

The safety and efficacy of light emitting diodes-based ultraviolet A1 phototherapy in bleomycin-induced scleroderma in mice

PURPOSE

To define the efficacy and safety of narrowband ultraviolet A1 (UVA1) for the treatment of dermal fibrosis in bleomycin-induced mouse model of scleroderma.

MATERIALS AND METHODS

42 DBA/2 strain mice were included in the study: healthy mice and mice with established scleroderma, treated with high or medium dose of UVA1. Non-treated groups served as control. The equipment emitting 365±5nm UVA1 radiation was used in the study. The average cumulative doses were 1200J/cm² for high and 600J/cm² for medium dose course. Histological analysis was performed for the evaluation of the dermal thickness and mast cells density. The expressions of p53 and Ki-67 proteins were assessed by immunohistochemical analyses.

RESULTS

Skin thickness of mice with scleroderma, treated with high and medium dose of UVA1, were lower (272.9±113.2μm and 394±125.9μm, respectively) in comparison to the dermal thickness of non-treated animals (599±55.7μm). The dermal mast cells count in mice with scleroderma was reduced after high and medium dose treatment to 11±1.7 and 13±2.2, respectively, as compared to that in non-treated mice (23±3.0). No significant upregulation of p53 nor Ki-67 proteins was observed in the skin of healthy mice and mice with scleroderma after high- and medium-dose of UVA1.

CONCLUSIONS

The results of this study indicate that 365nm UVA1 with the cumulative doses of 1200J/cm² and 600J/cm² is safe and effective for the dermal fibrosis treatment.

Expressions of p53 and PUMA in fibroblasts of systemic sclerosis patients are normal at transcription level

BACKGROUND

Systemic sclerosis (SSc) fibroblasts show resistance apoptosis mechanisms, which enhances the fibrosis stage of the disease. Impaired function of p53 upregulated modulator of apoptosis (PUMA) has been related to deficits in p53-dependant apoptosis pathway. This study aimed to evaluate the transcriptional levels of p53 and PUMA mRNAs in fibroblasts from SSc patients and compare it with healthy individuals.

METHODS

In this case-control study, skin biopsy samples were obtained from 19 patients with diffuse cutaneous SSc (DcSSc) and 16 healthy controls. Afterward, dermal fibroblasts were isolated and cultured. After extraction of total RNA from cultured fibroblasts, complementary DNA (cDNA) was synthesized. mRNA quantification was carried out using real-time PCR, SYBR Green PCR master mix, and specific primers for p53 and PUMA.

RESULTS

No significant alteration was observed in mRNA expression levels of p53 and PUMA (P = .99 and .23, respectively) in fibroblasts from SSc patients compared with controls.

CONCLUSIONS

Apoptosis pathways are impaired in fibroblasts from patients with SSc, leading to chronic fibrosis. Nonetheless, PUMA/p53 pathway may not be involved in dysfunction of apoptosis mechanisms in fibroblasts of patients with SSc.

Investigation of sensory neurogenic components in a bleomycin-induced scleroderma model using transient receptor potential vanilloid 1 receptor- and calcitonin gene-related peptide-knockout mice

OBJECTIVE

Along with their classic afferent function (nociception), capsaicin-sensitive transient receptor potential vanilloid 1 (TRPV1) receptor-expressing sensory nerve terminals exert local and systemic efferent activities. Activation of TRPV1 causes sensory neuropeptide release, which modulates the inflammation process. The aim of the present study was to examine the role of this modulatory role of TRPV1 receptor and that of calcitonin gene-related peptide (CGRP) in bleomycin-induced scleroderma, using transgenic mice.

METHODS

Cutaneous sclerosis was induced with daily subcutaneous injections of bleomycin for 30 days. Control groups were treated with phosphate buffered saline (PBS). TRPV1 receptor gene-deficient (TRPV1(-/-)) mice and CGRP-knockout (CGRP(-/-)) mice and their wild-type (WT) counterparts were investigated. A composite sclerosis score was calculated on the basis of thickening, leukocyte infiltration, and the amount/orientation of collagen bundles. Dermal thickness and the number of alpha-smooth muscle actin (alpha-SMA)-positive cells were also determined. The quantity of the collagen-specific amino acid hydroxyproline was measured by spectrophotometry.

RESULTS

Bleomycin treatment induced marked cutaneous thickening and fibrosis compared with that observed in control mice treated with PBS. The composite sclerosis score was 18% higher, dermal thickness was 19% higher, the number of alpha-SMA-positive cells was 47% higher, and the amount of hydroxyproline was 57% higher in TRPV1(-/-) mice than in their WT counterparts. Similarly, the composite sclerosis score was 47% higher, dermal thickness was 29% higher, the number of alpha-SMA-positive cells was 76% higher, and the amount of hydroxyproline was 30% higher in CGRP(-/-) mice than in the respective WT groups.

CONCLUSION

These results suggest that activation of the TRPV1 receptor by mediators of inflammation induces sensory neuropeptide release, which might exert protective action against fibrosis. We confirmed the protective role of CGRP in the development of cutaneous sclerosis.

Wnt/beta-catenin signaling interacts differentially with Ihh signaling in controlling endochondral bone and synovial joint formation

Both the Wnt/beta-catenin and Ihh signaling pathways play essential roles in crucial aspects of endochondral ossification: osteoblast differentiation, chondrocyte proliferation and hypertrophy. To understand the genetic interaction between these two signaling pathways, we have inactivated the beta-catenin gene and upregulated Ihh signaling simultaneously in the same cells during endochondral skeletal development using beta-catenin and patched 1 floxed alleles. We uncovered previously unexpected roles of Ihh signaling in synovial joint formation and the essential function of Wnt/beta-catenin signaling in regulating chondrocyte survival. More importantly, we found that Wnt and Ihh signaling interact with each other in distinct ways to control osteoblast differentiation, chondrocyte proliferation, hypertrophy, survival and synovial joint formation in the developing endochondral bone. Beta-catenin is required downstream of Ihh signaling and osterix expression for osteoblast differentiation. But in chondrocyte survival, beta-catenin is required upstream of Ihh signaling to inhibit chondrocyte apoptosis. In addition, Ihh signaling can inhibit chondrocyte hypertrophy and synovial joint formation independently of beta-catenin. However, there is a strong synergistic interaction between Wnt/beta-catenin and Ihh signaling in regulating synovial joint formation.

Fas- and FasL-deficient mice are resistant to the induction of bleomycin-induced scleroderma

We have recently shown that apoptosis is induced in the lesional skin in a murine scleroderma model by local bleomycin injections, and the apoptotic pathway was mainly mediated by Fas/Fas ligand (FasL) signaling. To further investigate the involvement of apoptosis in scleroderma, we examined whether the induction of dermal sclerosis is suppressed in Fas-deficient (lpr) and FasL-deficient (gld) mice. Results of histological examination showed that the induction of dermal sclerosis by bleomycin treatment was significantly suppressed in both lpr and gld mice, in comparison with wild-type mice. The ratio of collagen contents in the bleomycin-treated skin as compared with PBS-treated skin was significantly lower in both lpr and gld mice than that in wild-type mice. The number of TUNEL-positive infiltrating cells was markedly increased following bleomycin exposure (60 +/- 11.4/HPF) in comparison with PBS treatment (9.5 +/- 6.0/HPF) in wild-type mice, which was significantly decreased in both lpr (22 +/- 4.5/HPF, P < 0.05) and gld (26 +/- 6.1/HPF, P < 0.05) mice. Our findings that lpr and gld mice were resistant to the induction of dermal sclerosis by bleomycin further suggest that Fas/FasL pathway is an important contributor involved in the pathophysiology of bleomycin-induced dermal sclerosis.