Cell adhesion molecules regulate fibrotic process via Th1/Th2/Th17 cell balance in a bleomycin-induced scleroderma model

Circulating extracellular vesicles as predictive biomarkers of progressive interstitial lung disease in systemic sclerosis-a prospective cohort study

Objectives

To assess in patients with systemic sclerosis (SSc) the concentration of different subpopulations of circulating extracellular vesicles (EVs) and their association with the progression of interstitial lung disease (PF-ILD).

Methods

The prospective study included 59 SSc cases, 54% with interstitial lung disease (ILD). Plasma levels of EVs were analysed with flow cytometry and labelled as endothelial (EEVs), platelet (PEVs), leucocyte (LEVs), and EVs, expressing ICAM1, TF, or HMGB1. The presence of ILD was defined by HRCT. Lung functional tests were done every 3-6 months over a 3-year follow-up period. PF-ILD was defined as ≥10% decline of FVC % from baseline, or ≥5-9% along with a decline in DLCO of ≥15%.

Results

At baseline, 32/59 SSc patients had ILD, with a median disease duration of 3 years, and 38% were therapy naïve. In ILD patients, increased levels of all investigated EVs were found in respect to SSc patients without ILD (p < 0.05). Therapy naïve ILD cases had altered only ICAM1 + EVs compared to treated (p < 0.05). Multivariate regression analysis (MR) showed an independent association of PEVs (OR 1.004, 95% CI 1.001-1.01) and ICAM1 + EVs (OR 1.3, 95% CI 1.1-1.5) with ILD. During the follow-up period, 12/32 ILD patients developed PF-ILD, and in this group, the levels of all explored EVs were elevated compared to those without PF-ILD (p < 0.05). In an ROC analysis, all EVs showed a good ability to identify PF-ILD patients (p < 0.05). Cox MR confirmed the independent predictive value of ICAM1 + EVs (HR 1.1, 95% CI 1.01-1.1) with SSc PF-ILD.

Conclusion

Circulating EV levels are increased in SSc and correlate with ILD. In particular, ICAM1 + EVs may be a novel biomarker of PF-ILD, identifying SSc patients at high risk of progression who may require early aggressive treatment. Based on our results, the role of EVs in the pathogenesis and progression of ILD should be investigated further.

Dermal white adipose tissue: A new modulator in wound healing and regeneration

Dermal white adipose tissue (dWAT), distinguished by its origin from cells within the dermis and independence from subcutaneous fat tissue, has garnered significant attention for its non-metabolic functions. Characterized by strong communication with other components of the skin, dWAT mediates the proliferation and recruitment of various cell types by releasing adipogenic and inflammatory factors. Here, we focus on the modulatory role of dWAT at different stages during wound healing, highlighting its ability to mediate the adipocyte-to-myofibroblast transition which plays a pivotal role in the physiology and pathology processes of skin fibrosis, scarring, and aging. This review highlights the regulatory potential of dWAT in modulating wound healing processes and presents it as a target for developing therapeutic strategies aimed at reducing scarring and enhancing regenerative outcomes in skin-related disorders.

Inhibition of skin fibrosis via regulation of Th17/Treg imbalance in systemic sclerosis

Systemic sclerosis (SSc) is an idiopathic systemic connective tissue disorder characterized by fibrosis of the skin and internal organs, with growing interest in the imbalance between Th17 cells and regulatory T cells (Tregs) in the disease's pathogenesis. Heligmosomoides polygyrus (Hp), a natural intestinal parasite of mice, is known to induce Tregs in the host. We aimed to investigate the effects of Hp-induced Tregs on bleomycin-induced dermal fibrosis and clarify the role of the Th17/Treg balance in SSc fibrosis. Infection with Hp suppressed the development of bleomycin-induced dermal fibrosis and the infiltration of CD3+ T cells and CD68+ macrophages. Flow cytometric analysis revealed that Hp infection increased Tregs and inhibited the induction of bleomycin-induced Th17 cells. Treg depletion nullified these effects, suggesting that Hp-induced Tregs may prevent bleomycin-induced dermal fibrosis and inflammation. Analysis of the intestinal microbiota showed that bacteria positively correlated with Tregs exhibited a negative correlation with Th17 cells and dermal fibrosis in mice. SSc patients with severe fibrosis displayed a distinct microbiota profile. These results suggest that alterations in the intestinal microbiota may contribute to the Th17/Treg imbalance in SSc and its progression. Enhancing Tregs to regulate the Th17/Treg imbalance may present a promising strategy for suppressing fibrosis in SSc.

Dermal white adipose tissue: Development and impact on hair follicles, skin defense, and fibrosis

Dermal white adipose tissue (DWAT) is a distinctive adipose depot located within the lower dermis of the skin. Its significance as an ancillary fat in skin homoeostasis has recently received increased attention. New research has revealed that DWAT responses to skin pathology and physiology changes, impacting skin development, hair cycling, defense mechanisms, and fibrotic conditions. In this review, we explore the developmental process of DWAT and the adipose commitment timing of hypodermal. We explore the development process of DWAT and its pivotal role in regulating the hair cycle. We conclude the antibacterial activity and reversible dedifferentiation of dermal adipocytes in response to skin defense. Furthermore, we underscore the potentially crucial yet underestimated anti-fibrotic functions of DWAT-derived adipokines and adipocyte-myofibroblast transition.

Capsaicin ameliorate pulmonary fibrosis via antioxidant Nrf-2/ PPAR- γ pathway activation and inflammatory TGF-β1/ NF-κB/COX II pathway inhibition

Bleomycin is an effective antibiotic with a significant anticancer properties, but its use is limited due to its potential to induce dose-dependent pulmonary fibrosis. Therefore, this study aimed to assess the therapeutic potential of Capsaicin as an additional treatment to enhance patient tolerance to Bleomycin compared to the antifibrotic drug Pirfenidone. Pulmonary fibrosis was induced in rats through by a single intratracheal Bleomycin administration in day zero, followed by either Capsaicin or Pirfenidone treatment for 7 days. After the animals were sacrificed, their lungs were dissected and examined using various stains for macroscopic and histopathological evaluation. Additionally, the study assessed various antioxidant, anti-inflammatory, and antifibrotic parameters were assessed. Rats exposed to Bleomycin exhibited visible signs of fibrosis, histopathological alterations, increased collagen deposition, and elevated mucin content. Bleomycin also led to heightened increased inflammatory cells infiltration in the bronchoalveolar lavage, elevated fibrosis biomarkers such as hydroxyproline, alpha-smooth muscle actin (α-SMA) and transforming growth factor-beta (TGF-β1), increased inflammatory markers including tumor necrosis factor-alpha (TNF-α), interlukine-6 (Il-6), interlukine-1β (Il-1β) nuclear factor-kappa B (NF-κB), and Cyclooxygenase-2 (COX-2), and transforming growth factor-beta (TGF-β1),. Furthermore, it reduced the expression of peroxisome proliferator-activated receptor-gamma (PPAR-γ), increased oxidative stress biomarkers like nitric oxide (NO), malondialdehyde (MDA), myeloperoxidase (MPO) and protein carbonyl. Bleomycin also decreased the expression of nuclear factor erythroid 2-related factor 2 (Nrf-2), reduced glutathione (GSH), total antioxidant capacity, and the activities of catalase and superoxide dismutase (SOD). Treating the animals with Capsaicin and Pirfenidone following Bleomycin exposure resulted in improved lung macroscopic and microscopic characteristics, reduced collagen deposition (collagen I and collagen III) and mucin content, decreased inflammatory cell infiltration, lowered levels of hydroxyproline, α-SMA, and TGF-β1, decreased TNF-α, Il-6, Il-1β, NF-κB, and COX-2, increased PPAR-γ and Nrf-2 expression, and improvement improved in all oxidative stress biomarkers. In summary, Capsaicin demonstrates significant antifibrotic activity against Bleomycin-induced lung injury that may be attributed, at least in part, to the antioxidant and anti-inflammatory activities of Capsaicin mediated by upregulation of PPAR-γ and Nrf-2 expression and decreasing. TGF-β1, NF-κB and COX II proteins concentrations.

Systemic Sclerosis and Atherosclerosis: Potential Cellular Biomarkers and Mechanisms

Systemic sclerosis (SSc) is a rare systemic autoimmune disease of unknown etiology, which is characterized by endothelial dysfunction, pathologic vasculopathy, and increased tissue fibrosis. Traditionally, SSc has been regarded as a prototypical fibrotic disease in the family of systemic autoimmune diseases. Traditionally, emphasis has been placed on the three components of the pathogenesis of SSc: vascular, immune, and mesenchymal. Microvascular lesions, including endothelial dysfunction and smooth muscle cell migration into the intima of vessels in SSc, resemble the atherosclerotic process. Although microvascular disease is a hallmark of SSc, understanding the role of atherosclerotic vascular lesions in patients with SSc remains limited. It is still unknown whether the increased cardiovascular risk in SSc is related to specific cardiac complications (such as myocardial fibrosis) or the accelerated development of atherosclerosis. Different immune cell types appear to be involved in the immunopathogenesis of SSc via the activation of other immune cells, fibrosis, or vascular damage. Macrophages, B cells, T cells, dendritic cells, neutrophils, and endothelial cells have been reported to play the most important role in the pathogenesis of SSc and atherosclerosis. In our article, we reviewed the most significant and recent studies on the pathogenetic links between the development of SSc and the atherosclerotic process.

Targeting PRMT1 prevents acute and chronic graft-versus-host disease

Graft-versus-host disease (GVHD) is a common complication after allogeneic hematopoietic stem cell transplantation. Recent studies have reported that protein arginine methyltransferase 1 (PRMT1) is essential for the differentiation and proliferation of T and B cells. Therefore, it is possible that PRMT1 may play a critical role in GVHD. In this study, we observed that PRMT1 expression was upregulated in CD4+ T and B cells from chronic GVHD (cGVHD) patients and mice. However, the prophylactic use of a PRMT1 inhibitor significantly prevented cGVHD in mice by reducing the percentage of T helper (Th)17 cells, germinal center B cells, and plasma cells. The PRMT1 inhibitor also controlled acute GVHD (aGVHD) in mice by decreasing the percentage of Th17 cells. Moreover, inhibiting PRMT1 also weakened Th17 cell differentiation, B cell proliferation, and antibody production in cells from cGVHD patients. Additionally, further studies revealed that PRMT1 regulated B cell proliferation and antibody secretion by methylating isocitrate dehydrogenase 2 (IDH2). We observed asymmetric di-methylation of IDH2 by PRMT1 at arginine 353 promoted IDH2 homodimerization, which enhanced IDH2 activity, further increasing B cell proliferation and antibody production. Collectively, this study provides a rationale for the application of PRMT1 inhibitors in the prevention of aGVHD and cGVHD.

The Pathogenesis of Systemic Sclerosis: The Origin of Fibrosis and Interlink with Vasculopathy and Autoimmunity

Systemic sclerosis (SSc) is an autoimmune disease associated with increased mortality and poor morbidity, impairing the quality of life in patients. Whilst we know that SSc affects multiple organs via vasculopathy, inflammation, and fibrosis, its exact pathophysiology remains elusive. Microvascular injury and vasculopathy are the initial pathological features of the disease. Clinically, the vasculopathy in SSc is manifested as Raynaud's phenomenon (reversible vasospasm in reaction to the cold or emotional stress) and digital ulcers due to ischemic injury. There are several reports that medications for vasculopathy, such as bosentan and soluble guanylate cyclase (sGC) modulators, improve not only vasculopathy but also dermal fibrosis, suggesting that vasculopathy is important in SSc. Although vasculopathy is an important initial step of the pathogenesis for SSc, it is still unclear how vasculopathy is related to inflammation and fibrosis. In this review, we focused on the clinical evidence for vasculopathy, the major cellular players for the pathogenesis, including pericytes, adipocytes, endothelial cells (ECs), and myofibroblasts, and their signaling pathway to elucidate the relationship among vasculopathy, inflammation, and fibrosis in SSc.

E-Selectin, ICAM-1, and ET-1 Biomarkers Address the Concern of the Challenging Diagnosis of Interstitial Lung Disease in Patients with Autoimmune Diseases

Interstitial lung disease (ILD) constitutes the most critical comorbidity in autoimmune diseases (ADs) and its early diagnosis remains a challenge for clinicians. Accordingly, we evaluated whether E-selectin, ICAM-1, and ET-1, key molecules in endothelial damage, could be useful biomarkers for the detection of AD-ILD+. We recruited patients with rheumatoid arthritis (RA)-ILD+ (n = 21) and systemic sclerosis (SSc)-ILD+ (n = 21). We included comparison groups of patients: RA-ILD- (n = 25), SSc-ILD- (n = 20), and idiopathic pulmonary fibrosis (IPF) (n = 21). Serum levels of these proteins were determined by ELISA. E-selectin, ICAM-1, and ET-1 serum levels were increased in RA-ILD+ and IPF patients in comparison to RA-ILD- patients. Additionally, SSc-ILD+ and IPF patients exhibited higher ICAM-1 levels than those with SSc-ILD-. The ability of E-selectin, ICAM-1, and ET-1 to discriminate RA-ILD+ from RA-ILD- patients, and ICAM-1 to distinguish SSc-ILD+ from SSc-ILD- patients was confirmed using ROC curve analysis. Furthermore, elevated levels of ET-1 and E-selectin correlated with lung function decline in RA-ILD+ and SSc-ILD+ patients, respectively. In conclusion, our findings support the relevant role of E-selectin, ICAM-1, and ET-1 in RA-ILD+ patients as well as of ICAM-1 in SSc-ILD+ patients, constituting potential screening blood biomarkers of ILD in AD. Moreover, this study suggests ET-1 and E-selectin as possible indicators of worsening lung function in RA-ILD+ and SSc-ILD+ patients, respectively.

Cell Adhesion Molecules in Fibrotic Diseases

Mechanisms underlying the pathogenesis of tissue fibrosis remain incompletely understood. Emerging evidence suggests that cell adhesion molecules (CAMs) are critical in fibrotic progression in many organs, including lung, kidney, skin, and liver. CAMs promote cell-cell and cell-extracellular matrix (ECM) interactions to maintain tissue architecture and normal function in homeostasis. However, dysregulated expression and function of CAMs can lead to chronic inflammation and tissue fibrosis. The major families of CAMs include integrins, cadherins, selectins, and immunoglobulins. Here, we review the role of the CAMs in fibrosis development across various organs with a focus on integrins and cadherins, and discuss their respective roles in the development of pulmonary fibrosis.

Sex-Mediated Differences in TNF Signaling- and ECM-Related Gene Expression in Aged Rat Kidney

Aging leads to the functional decline of an organism, which is associated with age and sex. To understand the functional change of kidneys depending on age and sex, we carried out a transcriptome analysis using RNA sequencing (RNA-Seq) data from rat kidneys. Four differentially expressed gene (DEG) sets were generated according to age and sex, and Gene Ontology analysis and overlapping analysis of Kyoto Encyclopedia of Genes and Genomes pathways were performed for the DEG sets. Through the analysis, we revealed that inflammation- and extracellular matrix (ECM)-related genes and pathways were upregulated in both males and females during aging, which was more prominent in old males than in old females. Furthermore, quantitative real-time PCR analysis confirmed that the expression of tumor necrosis factor (TNF) signaling-related genes, Birc3, Socs3, and Tnfrsf1b, and ECM-related genes, Cd44, Col3a1, and Col5a2, which showed that the genes were markedly upregulated in males and not females during aging. Also, hematoxylin-eosin (H&E) staining for histological analysis showed that renal damage was highly shown in old males rather than old females. In conclusion, in the rat kidney, the genes involved in TNF signaling and ECM accumulation are upregulated in males more than in females during aging. These results suggest that the upregulation of the genes may have a higher contribution to age-related kidney inflammation and fibrosis in males than in females.

The role of PD-1/PD-L1 axis in idiopathic pulmonary fibrosis: Friend or foe?

Idiopathic pulmonary fibrosis (IPF) is a devastating interstitial lung disease with a bleak prognosis. Mounting evidence suggests that IPF shares bio-molecular similarities with lung cancer. Given the deep understanding of the programmed cell death-1 (PD-1)/programmed death-ligand 1 (PD-L1) pathway in cancer immunity and the successful application of immune checkpoint inhibitors (ICIs) in lung cancer, recent studies have noticed the role of the PD-1/PD-L1 axis in IPF. However, the conclusions are ambiguous, and the latent mechanisms remain unclear. In this review, we will summarize the role of the PD-1/PD-L1 axis in IPF based on current murine models and clinical studies. We found that the PD-1/PD-L1 pathway plays a more predominant profibrotic role than its immunomodulatory role in IPF by interacting with multiple cell types and pathways. Most preclinical studies also indicated that blockade of the PD-1/PD-L1 pathway could attenuate the severity of pulmonary fibrosis in mice models. This review will bring significant insights into understanding the role of the PD-1/PD-L1 pathway in IPF and identifying new therapeutic targets.

Identification and validation of key immune-related genes with promising diagnostic and predictive value in systemic sclerosis

AIMS

To screen and confirm key immune-related genes (IRGs) with diagnostic and predictive value in systemic sclerosis (SSc) and provide potential therapeutic targets for patients with SSc.

MATERIALS AND METHODS

In Gene Expression Omnibus database (GEO), four datasets of gene expression profiling related to SSc were downloaded and used for the analysis in this study. After differential analysis of SSc cases and controls in GSE130955, the differentially expressed genes (DEGs) were overlapped with IRGs to obtain the immune-related differentially expressed genes (IR-DEGs) in SSc. In addition, functional annotation and pathway enrichment of IR-DEGs were conducted. The protein-protein interaction network (PPI) was constructed to identify key IR-DEGs. Using GSE58095, GSE181549 and GSE130953, the diagnostic and predictive abilities for the key IR-DEGs in SSc were validated. Finally, the screened key genes were confirmed in skin derived bleomycin (BLM)-induced SSc mice by Real-time PCR.

KEY FINDINGS

NGFR, TNFSF13B, FCER1G, GIMAP5, TYROBP and CSF1R may have important or very high diagnostic value for SSc. TYROBP and TNFSF13B had moderate and mild predictive value respectively in SSc patients after treatment. Real-time PCR assay further confirmed that the expressions of Ngfr, Tyrobp, Csf1r, Fcer1g and Gimap5 were significantly higher in skin of BLM-induced SSc mice than that in controls.

SIGNIFICANCE

The key IR-DEGs, including NGFR, TNFSF13B, TYROBP, CSF1R, FCER1G and GIMAP5, may become auxiliary diagnostic indicators and potential biomarkers for SSc. Moreover, TNFSF13B and TYROBP could have good prospects as predictive indicators in SSc patients that accepted cyclophosphamide or transplantation therapy.

Combined analyses of RNA-sequence and Hi-C along with GWAS loci—A novel approach to dissect keloid disorder genetic mechanism

Keloid disorder is a tumour-like disease with invasive growth and a high recurrence rate. Genetic contribution is well expected due to the presence of autosomal dominant inheritance and various genetic mutations in keloid lesions. However, GWAS failed to reveal functional variants in exon regions but single nucleotide polymorphisms in the non-coding regions, suggesting the necessity of innovative genetic investigation. This study employed combined GWAS, RNA-sequence and Hi-C analyses to dissect keloid disorder genetic mechanisms using paired keloid tissues and normal skins. Differentially expressed genes, miRNAs and lncRNAs mined by RNA-sequence were identified to construct a network. From which, 8 significant pathways involved in keloid disorder pathogenesis were enriched and 6 of them were verified. Furthermore, topologically associated domains at susceptible loci were located via the Hi-C database and ten differentially expressed RNAs were identified. Among them, the functions of six molecules for cell proliferation, cell cycle and apoptosis were particularly examined and confirmed by overexpressing and knocking-down assays. This study firstly revealed unknown key biomarkers and pathways in keloid lesions using RNA-sequence and previously reported mutation loci, indicating a feasible approach to reveal the genetic contribution to keloid disorder and possibly to other diseases that are failed by GWAS analysis alone.

Keloid disorder is a benign skin tumour characterized by uncontrolled fibroproliferative tissue growth, which only occurs in human beings with severe reoccurrence post-therapy. It affects several hundred million people with difficulty to control its growth and relapse. It has been long thought that exonic gene mutations must play an important role, but large-scaled GWAS analyses only revealed 3 single nucleotide polymorphisms in the non-coding regions as previously reported. For the first time, this study demonstrated that the true genetic mechanism is likely to be the dysfunctional epigenetic regulation caused by mutations in regulatory elements at the non-coding region as revealed by the combined analyses of GWAS, RNA-sequence and Hi-C data. This approach may lead to the breakthrough of keloid disorder genetic/epigenetic mechanism, if further large-scaled analyses are performed along with human keloid tissue Hi-C data.

Targeting the PSGL-1 Immune Checkpoint Promotes Immunity to PD-1-Resistant Melanoma

Immune-checkpoint inhibitors have had impressive efficacy in some patients with cancer, reinvigorating long-term durable immune responses against tumors. Despite the clinical success of these therapies, most patients with cancer continue to be unresponsive to these treatments, highlighting the need for novel therapeutic options. Although P-selectin glycoprotein ligand-1 (PSGL-1) has been shown to inhibit immune responses in a variety of disease models, previous work has yet to address whether PSGL-1 can be targeted therapeutically to promote antitumor immunity. Using an aggressive melanoma tumor model, we targeted PSGL-1 in tumor-bearing mice and found increased effector CD4+ and CD8+ T-cell responses and decreased regulatory T cells (Treg) in tumors. T cells exhibited increased effector function, activation, and proliferation, which delayed tumor growth in mice after anti-PSGL-1 treatment. Targeting PD-1 in PSGL-1-deficient, tumor-bearing mice led to an increased frequency of mice with complete tumor eradication. Targeting both PSGL-1 and PD-1 in wild-type tumor-bearing mice also showed enhanced antitumor immunity and slowed melanoma tumor growth. Our findings showed that therapeutically targeting the PSGL-1 immune checkpoint can reinvigorate antitumor immunity and suggest that targeting PSGL-1 may represent a new therapeutic strategy for cancer treatment.

Immunological Regulation of Intestinal Fibrosis in Inflammatory Bowel Disease

Intestinal fibrosis is a late-stage phenotype of inflammatory bowel disease (IBD), which underlies most of the long-term complications and surgical interventions in patients, particularly those with Crohn's disease. Despite these issues, antifibrotic therapies are still scarce, mainly due to the current lack of understanding concerning the pathogenetic mechanisms that mediate fibrogenesis in patients with chronic intestinal inflammation. In the current review, we summarize recent evidence regarding the cellular and molecular factors of innate and adaptive immunity that are considered critical for the initiation and amplification of extracellular matrix deposition and stricture formation. We focus on the role of cytokines by dissecting the pro- vs antifibrotic components of the immune response, while taking into consideration their temporal association to the progressive stages of the natural history of IBD. We critically present evidence from animal models of intestinal fibrosis and analyze inflammation-fibrosis interactions that occur under such experimental scenarios. In addition, we comment on recent findings from large-scale, single-cell profiling of fibrosis-relevant populations in IBD patients. Based on such evidence, we propose future potential targets for antifibrotic therapies to treat patients with IBD.

Increased L-Selectin on Monocytes Is Linked to the Autoantibody Profile in Systemic Sclerosis

Monocytes are known to be implicated in the pathogenesis of systemic sclerosis (SSc), as they exert prominent migratory, adhesive, and chemotactic properties. The aim of our study was to characterize the surface expression of adhesion/chemotactic molecules (CD62L, CD11b, CCR2, CCR5) on the SSc monocytes and determine correlations with the clinical presentation of SSc. We included 38 SSc patients and 36 healthy age-and sex-matched controls. Isolated monocytes, as well as in vitro serum-treated monocytes, were analyzed by flow cytometry; additionally, soluble CD62L was measured in serum. We found increased soluble CD62L in the SSc serum samples and increased CD62L on the surface of the SSc monocytes in the in the same set of patients. Among samples with determined SSc-specific autoantibodies, the surface CD62L was the lowest in patients positive for anti-PM/Scl autoantibodies and the highest in patients with anti-topoisomerase I autoantibodies (ATA). The treatment of isolated healthy monocytes with ATA-positive SSc serum resulted in increased surface CD62L expression. Moreover, surface CCR5 was reduced on the monocytes from SSc patients with interstitial lung disease but also, along with CCR2, negatively correlated with the use of analgesics/anti-inflammatory drugs and immunosuppressants. In conclusion, increased CD62L on SSc monocytes, particularly in ATA-positive patients, provides new insights into the pathogenesis of SSc and suggests CD62L as a potential therapeutic target.

1,25OH-Vitamin D3 and IL-17 Inhibition Modulate Pro-Fibrotic Cytokines Production in Peripheral Blood Mononuclear Cells of Patients with Systemic Sclerosis

Objectives: IL-17 modulates the synthesis of several molecules involved in the pathogenesis of Systemic Sclerosis (SSc). Vitamin D (1,25(OH)₂D3) shows anti-fibrotic properties and it is able to affect the IL-17 production in several experimental conditions. The aim of this study is to assess the production of IL-17A and pro-fibrotic cytokines in peripheral blood mononuclear cells (PBMCs) from subjects with SSc in basal conditions and after treatment with 1,25(OH)2D3 and IL-17A neutralizing antibodies. Methods: The production of IL-17A and pro-fibrotic cytokines (TGFβ, CTGF and FGF2) in PBMCs obtained from 51 SSc patients and 31 healthy subjects was assessed both in basal conditions and in presence of anti-IL17A antibodies and several concentrations of 1,25(OH)₂D3. The association of cytokines production with clinical disease characteristics and the in vitro effect of 1,25(OH)₂D3 and IL-17A inhibition were assessed. Results: PBMCs from SSc subjects produced higher amount IL-17A, TGFβ, CTGF and FGF2 compared to healthy controls. IL17, TGFβ, CTGF and FGF2 levels were higher in SSc patients with interstitial lung disease and digital ulcers, whereas IL-17A production was lower in patients with PAH. IL- 17A inhibition reduced the production of FGF2, whereas enhanced the synthesis of TGFβ and CTGF. 1,25(OH)₂D3 decreased the production of IL17A and pro-fibrotic cytokines in a dose- dependent manner. Conclusions: IL-17A is involved in the regulation of fibrogenesis in SSc, and could represent an intriguing potential therapeutic target, even if its role remains controversial. 1,25(OH)₂D3 inhibits both IL-17A and pro-fibrotic cytokines, confirming its potential anti-fibrotic effect.

Interleukin-31 promotes fibrosis and T helper 2 polarization in systemic sclerosis

Systemic sclerosis (SSc) is a chronic multisystem disorder characterized by fibrosis and autoimmunity. Interleukin (IL)-31 has been implicated in fibrosis and T helper (Th) 2 immune responses, both of which are characteristics of SSc. The exact role of IL-31 in SSc pathogenesis is unclear. Here we show the overexpression of IL-31 and IL-31 receptor A (IL-31RA) in dermal fibroblasts (DFs) from SSc patients. We elucidate the dual role of IL-31 in SSc, where IL-31 directly promotes collagen production in DFs and indirectly enhances Th2 immune responses by increasing pro-Th2 cytokine expression in DFs. Furthermore, blockade of IL-31 with anti-IL-31RA antibody significantly ameliorates fibrosis and Th2 polarization in a mouse model of SSc. Therefore, in addition to defining IL-31 as a mediator of fibrosis and Th2 immune responses in SSc, our study provides a rationale for targeting the IL-31/IL-31RA axis in the treatment of SSc.

Systemic sclerosis (SSc) disease involves multisystem fibrosis and autoimmunity with limited treatment options. Here the authors demonstrate that IL-31 and IL-31RA are overexpressed in dermal fibroblasts from SSc patients and show that fibrosis and cytokine release can be reduced upon blocking of IL-31/IL-31RA.

[Application of lymphocytes test in peripheral blood of patients with systemic sclerosis during the treatment]

OBJECTIVE

To explore the significance of lymphocytes in systemic sclerosis (SSc), by detecting the levels of T lymphocytes, B lymphocytes and natural killer (NK) cells, and analyzing the correlation between the lymphocytes and clinical laboratory indexes.

METHODS

The numbers and proportion of T, CD4⁺T, CD8⁺T, B, and NK cells were detected by flow cytometry in peripheral blood of 32 SSc patients who had taken immunosuppressive drugs and 30 healthy controls (HC). The comparison of the lymphocyte subsets in SSc with them in the HC groups, and the correlation between the lymphocytes and other clinical and laboratory indicators were analyzed by the relevant statistical analysis.

RESULTS

Compared with the HC group, the numbers of T, CD4⁺T, CD8⁺T, and NK cells in peripheral blood of SSc group, who had taken immunosuppressive drugs, were significantly decreased (P < 0.05). More-over, the proportion of NK cells in peripheral blood of the SSc group was also significantly lower than that in the HC group (P=0.004). In addition, all the lymphocyte subsets were decreased in peripheral blood of more than 65% of the SSc patients who had taken immunosuppressive drugs. Compared with CD4⁺T normal group, the positivity of Raynaud's phenomenon, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) was significantly increased in CD4⁺T reduction group, respectively (P＝0.024, P < 0.001, P=0.018). ESR was higher in CD8⁺T reduction group than CD8⁺T normal group (P＝0.022). The prevalence of fingertip ulcer was significantly increased in B cell decrease group (P=0.019). Compared with NK cell normal group, the prevalence of fingertip ulcer was significantly increased in NK cell lower group (P=0.033), IgM was remarkablely decreased yet (P=0.049). The correlation analysis showed that ESR was negatively correlated with the counts of T lymphocytes (r＝－0.455, P＝0.009), CD4⁺T lymphocytes (r＝－0.416, P＝0.018), CD8⁺T lymphocytes (r＝－0.430, P=0.014), B cells (r＝－0.366, P＝0.039).

CONCLUSION

The number of CD4⁺T, CD8⁺T, B, and NK cells significantly decreased in peripheral blood of SSc patients who had used immunosuppressive drugs, some lymphocyte subsets might be related with Raynaud's phenomenon and fingertip ulcer, and reflected the disease activity by negatively correlated with ESR and CRP; the numbers of lymphocyte subsets in peripheral blood should be detected regularly in SSc patients who had taken immunosuppressive drugs.

Platelet Phagocytosis via P-selectin Glycoprotein Ligand 1 and Accumulation of Microparticles in Systemic Sclerosis

OBJECTIVE

It is unclear why activated platelets and platelet-derived microparticles (MPs) accumulate in the blood of patients with systemic sclerosis (SSc). This study was undertaken to investigate whether defective phagocytosis might contribute to MP accumulation in the blood of patients with SSc.

METHODS

Blood samples were obtained from a total of 81 subjects, including 25 patients with SSc and 26 patients with stable coronary artery disease (CAD). Thirty sex- and age-matched healthy volunteers served as controls. Studies were also conducted in NSG mice, in which the tail vein of the mice was injected with MPs, and samples of the lung parenchyma were obtained for analysis of the pulmonary microvasculature. Tissue samples from human subjects and from mice were assessed by flow cytometry and immunochemical analyses for determination of platelet-neutrophil interactions, phagocytosis, levels and distribution of P-selectin, P-selectin glycoprotein ligand 1 (PSGL-1), and HMGB1 on platelets and MPs, and concentration of byproducts of neutrophil extracellular trap (NET) generation/catabolism.

RESULTS

Activated P-selectin+ platelets and platelet-derived HMGB1+ MPs accumulated in the blood of SSc patients but not in the blood of healthy controls. Patients with CAD, a vasculopathy independent of systemic inflammation, had fewer P-selectin+ platelets and a negligible number of MPs. The expression of the receptor for P-selectin, PSGL-1, in neutrophils from SSc patients was significantly decreased, raising the possibility that phagocytes in SSc do not recognize activated platelets, leading to a failure of phagocytosis and continued neutrophil release of MPs. As evidence of this process, activated platelets were not detected in the neutrophils from SSc patients, whereas they were consistently present in the neutrophils from patients with CAD. HMGB1+ MPs elicited generation of NETs, which were only detected in the plasma of SSc patients. In mice, P-selectin-PSGL-1 interaction resulted in platelet phagocytosis in vitro and influenced the ability of MPs to elicit NETs, endothelial activation, and migration of leukocytes through the pulmonary microvasculature.

CONCLUSION

The clearance of activated platelets via PSGL-1 limits the undesirable effects of MP-elicited neutrophil activation. This balance is disrupted in patients with SSc. Its reconstitution might curb vascular inflammation and prevent fibrosis.

Repurposing mesalazine against cardiac fibrosis in vitro

Cardiovascular diseases are exacerbated and driven by cardiac fibrosis. TGFβ induces fibroblast activation and differentiation into myofibroblasts that secrete excessive extracellular matrix proteins leading to stiffening of the heart, concomitant cardiac dysfunction, and arrhythmias. However, effective pharmacotherapy for preventing or reversing cardiac fibrosis is presently unavailable. Therefore, drug repurposing could be a cost- and time-saving approach to discover antifibrotic interventions. The aim of this study was to investigate the antifibrotic potential of mesalazine in a cardiac fibroblast stress model. TGFβ was used to induce a profibrotic phenotype in a human cardiac fibroblast cell line. After induction, cells were treated with mesalazine or solvent control. Fibroblast proliferation, key fibrosis protein expression, extracellular collagen deposition, and mechanical properties were subsequently determined. In response to TGFβ treatment, fibroblasts underwent a profound phenoconversion towards myofibroblasts, determined by the expression of fibrillary αSMA. Mesalazine reduced differentiation nearly by half and diminished fibroblast proliferation by a third. Additionally, TGFβ led to increased cell stiffness and adhesion, which were reversed by mesalazine treatment. Collagen 1 expression and deposition-key drivers of fibrosis-were significantly increased upon TGFβ stimulation and reduced to control levels by mesalazine. SMAD2/3 and ERK1/2 phosphorylation, along with reduced nuclear NFκB translocation, were identified as potential modes of action. The current study provides experimental pre-clinical evidence for antifibrotic effects of mesalazine in an in vitro model of cardiac fibrosis. Furthermore, it sheds light on possible mechanisms of action and suggests further investigation in experimental and clinical settings.

Serum TARC Levels in Patients with Systemic Sclerosis: Clinical Association with Interstitial Lung Disease

Systemic sclerosis (SSc) is a multisystem fibrotic disorder with autoimmune background. Accumulating evidence has highlighted the importance of T helper (Th) 2 cells in the pathogenesis of SSc and its complications. Because thymus and activation-regulated chemokine (TARC) is a potent chemoattractant for Th2 cells, we measured serum TARC levels in SSc patients and analyzed their correlation with interstitial lung disease (ILD), a major complication of SSc. Serum TARC levels were significantly elevated in patients with SSc, especially in those with the diffuse subtype, compared with healthy controls. In particular, dcSSc patients with SSc-associated ILD (SSc-ILD) showed higher TARC levels than those without SSc-ILD. However, there was no significant correlation between serum TARC levels and pulmonary function in SSc patients. Serum TARC levels did not correlate with serum levels of interleukin-13, an important Th2 cytokine, either. Furthermore, in the longitudinal study, serum TARC levels did not predict the onset or progression of SSc-ILD in patients with SSc. These results were in contrast with those of KL-6 and surfactant protein D, which correlated well with the onset, severity, and progression of SSc-ILD. Overall, these results suggest that serum TARC levels are not suitable for monitoring the disease activity of SSc-ILD.

A monoclonal antibody to Siglec-8 suppresses non-allergic airway inflammation and inhibits IgE-independent mast cell activation

In addition to their well characterized role in mediating IgE-dependent allergic diseases, aberrant accumulation and activation of mast cells (MCs) is associated with many non-allergic inflammatory diseases, whereby their activation is likely triggered by non-IgE stimuli (e.g., IL-33). Siglec-8 is an inhibitory receptor expressed on MCs and eosinophils that has been shown to inhibit IgE-mediated MC responses and reduce allergic inflammation upon ligation with a monoclonal antibody (mAb). Herein, we evaluated the effects of an anti-Siglec-8 mAb (anti-S8) in non-allergic disease models of experimental cigarette-smoke-induced chronic obstructive pulmonary disease and bleomycin-induced lung injury in Siglec-8 transgenic mice. Therapeutic treatment with anti-S8 inhibited MC activation and reduced recruitment of immune cells, airway inflammation, and lung fibrosis. Similarly, using a model of MC-dependent, IL-33-induced inflammation, anti-S8 treatment suppressed neutrophil influx, and cytokine production through MC inhibition. Transcriptomic profiling of MCs further demonstrated anti-S8-mediated downregulation of MC signaling pathways induced by IL-33, including TNF signaling via NF-κB. Collectively, these findings demonstrate that ligating Siglec-8 with an antibody reduces non-allergic inflammation and inhibits IgE-independent MC activation, supporting the evaluation of an anti-Siglec-8 mAb as a therapeutic approach in both allergic and non-allergic inflammatory diseases in which MCs play a role.

Mesenchymal stem cell as a novel approach to systemic sclerosis; current status and future perspectives

Systemic sclerosis is a rare chronic autoimmune disease with extensive microvascular injury, damage of endothelial cells, activation of immune responses, and progression of tissue fibrosis in the skin and various internal organs. According to epidemiological data, women's populations are more susceptible to systemic sclerosis than men. Until now, various therapeutic options are employed to manage the symptoms of the disease. Since stem cell-based treatments have developed as a novel approach to rescue from several autoimmune diseases, it seems that stem cells, especially mesenchymal stem cells as a powerful regenerative tool can also be advantageous for systemic sclerosis treatment via their remarkable properties including immunomodulatory and anti-fibrotic effects. Accordingly, we discuss the contemporary status and future perspectives of mesenchymal stem cell transplantation for systemic sclerosis.

The Pathogenesis of Systemic Sclerosis: An Understanding Based on a Common Pathologic Cascade across Multiple Organs and Additional Organ-Specific Pathologies

Systemic sclerosis (SSc) is a multisystem autoimmune and vascular disease resulting in fibrosis of various organs with unknown etiology. Accumulating evidence suggests that a common pathologic cascade across multiple organs and additional organ-specific pathologies underpin SSc development. The common pathologic cascade starts with vascular injury due to autoimmune attacks and unknown environmental factors. After that, dysregulated angiogenesis and defective vasculogenesis promote vascular structural abnormalities, such as capillary loss and arteriolar stenosis, while aberrantly activated endothelial cells facilitate the infiltration of circulating immune cells into perivascular areas of various organs. Arteriolar stenosis directly causes pulmonary arterial hypertension, scleroderma renal crisis and digital ulcers. Chronic inflammation persistently activates interstitial fibroblasts, leading to the irreversible fibrosis of multiple organs. The common pathologic cascade interacts with a variety of modifying factors in each organ, such as keratinocytes and adipocytes in the skin, esophageal stratified squamous epithelia and myenteric nerve system in gastrointestinal tract, vasospasm of arterioles in the heart and kidney, and microaspiration of gastric content in the lung. To better understand SSc pathogenesis and develop new disease-modifying therapies, it is quite important to understand the complex pathogenesis of SSc from the two distinct perspectives, namely the common pathologic cascade and additional organ-specific pathologies.

Blockade of IL-17 signaling reverses alcohol-induced liver injury and excessive alcohol drinking in mice

Chronic alcohol abuse has a detrimental effect on the brain and liver. There is no effective treatment for these patients, and the mechanism underlying alcohol addiction and consequent alcohol-induced damage of the liver/brain axis remains unresolved. We compared experimental models of alcoholic liver disease (ALD) and alcohol dependence in mice and demonstrated that genetic ablation of IL-17 receptor A (IL-17ra-/-) or pharmacological blockade of IL-17 signaling effectively suppressed the increased voluntary alcohol drinking in alcohol-dependent mice and blocked alcohol-induced hepatocellular and neurological damage. The level of circulating IL-17A positively correlated with the alcohol use in excessive drinkers and was further increased in patients with ALD as compared with healthy individuals. Our data suggest that IL-17A is a common mediator of excessive alcohol consumption and alcohol-induced liver/brain injury, and targeting IL-17A may provide a novel strategy for treatment of alcohol-induced pathology.

Phlorofucofuroeckol A from Ecklonia cava ameliorates TGF-β1-induced fibrotic response of human tracheal fibroblasts via the downregulation of MAPKs and SMAD 2/3 pathways inactivated TGF-β receptor

The objective of this study was to investigate inhibitory effects of a bioactive compound isolated from Ecklonia cava on fibrotic responses to transforming growth factor-β1 (TGF-β1)-stimulated Hs680. Tr human tracheal fibroblasts and the associated mechanisms of action. Post consecutive purification, a potent bioactive compound was identified phlorofucofuroeckol A. Phlorofucofuroeckol A significantly suppressed protein expression levels of collagen type I and α-smooth muscle actin (α-SMA) on TGF-β1-stimulated Hs680. Tr human tracheal fibroblasts. Further mechanistic studies determined that phlorofucofuroeckol A suppressed the phosphorylation of p38, extracellular regulated kinase (ERK), and c-Jun N-terminal kinase (JNK) and SMAD 2/3 in TGF-β1-stimulated Hs680. Tr human tracheal fibroblasts. Moreover, we could show that phlorofucofuroeckol A inhibits binding of TGF-β1 to its TGF-β receptor by molecular docking. Based on the results, we propose that phlorofucofuroeckol A suppresses the MAPKs and SMAD 2/3 pathways and relieves cellular fibrotic activities, thus preventing tracheal fibrosis.

IL-17A Softens the Skin: Antifibrotic Properties of IL-17A in Systemic Sclerosis

IL-17A is abundant in scleroderma skin, but its pathologic role has remained unclear. In the Journal of Investigative Dermatology, Dufour et al. (2020) demonstrate a new role for IL-17A as an antifibrotic agent in scleroderma through modulation of keratinocyte responses to transforming growth factor-β and shifting of fibroblast responses from profibrotic to antifibrotic.

Trained immunity modulates inflammation-induced fibrosis

Chronic inflammation and fibrosis can result from inappropriately activated immune responses that are mediated by macrophages. Macrophages can acquire memory-like characteristics in response to antigen exposure. Here, we show the effect of BCG or low-dose LPS stimulation on macrophage phenotype, cytokine production, chromatin and metabolic modifications. Low-dose LPS training alleviates fibrosis and inflammation in a mouse model of systemic sclerosis (SSc), whereas BCG-training exacerbates disease in this model. Adoptive transfer of low-dose LPS-trained or BCG-trained macrophages also has beneficial or harmful effects, respectively. Furthermore, coculture with low-dose LPS trained macrophages reduces the fibro-inflammatory profile of fibroblasts from mice and patients with SSc, indicating that trained immunity might be a phenomenon that can be targeted to treat SSc and other autoimmune and inflammatory fibrotic disorders.

Innate immune cells can be trained by some stimuli or pathogen exposures to be metabolically and epigenetically altered such that they have different responses to subsequent exposures. Here the authors show that low-dose LPS trained macrophages and BCG-trained macrophages have opposing effects on fibrosis and inflammation in the context of systemic sclerosis.

Adipose-derived stromal/stem cells successfully attenuate the fibrosis of scleroderma mouse models

AIM

Systemic sclerosis (SSc) is an autoimmune disease characterized by skin and lung fibrosis. Although SSc has a high mortality risk, an effective treatment for the disease has not been established yet. Mesenchymal stromal/stem cells (MSCs) are multipotential nonhematopoietic progenitor cells that have the ability to regulate immune responses. Adipose-derived stromal/stem cells (ASCs), one of the types of MSCs, have the advantage of accessibility and potent immunomodulatory effects when compared with other MSCs, such as bone marrow-derived MSCs. This study aimed to investigate the antifibrotic effect of ASCs in scleroderma mouse models, including bleomycin-induced scleroderma and sclerodermatous chronic graft-versus-host disease (Scl-cGVHD) models.

METHOD

ASCs were intravenously administered to a bleomycin-induced scleroderma or Scl-cGVHD model on day 0. We compared the skin and lung fibrosis of scleroderma model mice between the ASC-treated group and control group.

RESULTS

Administration of ASCs attenuated the skin and lung fibrosis of bleomycin-induced scleroderma and Scl-cGVHD model mice compared to that in the control mice. Immunohistochemical staining showed that ASCs suppressed the infiltration of CD4⁺ , CD8⁺ T cells and macrophages into the dermis of bleomycin model mice compared to that in control mice. In addition, ASCs attenuated the messenger RNA expression of collagen and fibrogenic cytokines, such as interleukin (IL)-6 and IL-13, in the skin of bleomycin model mice. ASCs also reduced the frequency of fibrogenic cytokine-producing CD4⁺ T cells and effector B cells in the spleen of bleomycin model mice.

CONCLUSION

ASCs could prove to be a potential therapeutic agent for use in patients with SSc.

Biomarkers of Systemic Lupus Erythematosus and Systemic Sclerosis diseases activity in a sample of Egyptian patients :Soluble Intercellular Adhesion Molecule-1 and Soluble Interleukin-2 Receptor, Case Control Study

Systemic Lupus Erythematosus (SLE) and systemic sclerosis (SSc) are systemic inflammatory autoimmune disorders characterized by a large spectrum of clinical and laboratory features. The aim of the present study was to investigate the possible use of serum level of soluble intercellular adhesion molecule-1(sICAM-1) and soluble interleukin-2 receptor (sIL-2Ra) as biomarkers for monitoring of SLE and SSc disease activity. Moreover, it aimed to compare the specificity and sensitivity as well as cut-off value of both biomarkers in a sample of Egyptian patients. 50 SLE patients, 30 SSc patients and 60 age and sex matched healthy controls were enrolled in our study. sICAM-1and sIL-2Ra were measured in serum samples obtained from all participants. In addition to Erythosedimentation rate (ESR), complete blood count (CBC), Antineuclearantibodies (ANA) estimation, disease activity of both diseases were also assessed. sICAM-1and sIL-2Ra levels were higher in SLE and SSc patients versus control. Both parameters are correlated with each other as well as the activity parameters. A cut-off levels of 455.59 (ng/ml) &2525935 (pg/ml) in both SLE & SSs respectively was observed with the highest specificity and sensitivity. It could be concluded that sICAM-1 and sIL-2Ra are noninvasive biomarkers for SLE and SSc that could play a pathophysiologic role in development and progression of both diseases. Moreover, sICAM-1 and sIL-2Ra are correlated with the disease activity at cut-off values of 455.59 (ng/ml) & 2525935(pg/ml) respectively.

New insights into the genetics and epigenetics of systemic sclerosis

Systemic sclerosis (SSc) is a severe autoimmune disease that is characterized by vascular abnormalities, immunological alterations and fibrosis of the skin and internal organs. The results of genetic studies in patients with SSc have revealed statistically significant genetic associations with disease manifestations and progression. Nevertheless, genetic susceptibility to SSc is moderate, and the functional consequences of genetic associations remain only partially characterized. A current hypothesis is that, in genetically susceptible individuals, epigenetic modifications constitute the driving force for disease initiation. As epigenetic alterations can occur years before fibrosis appears, these changes could represent a potential link between inflammation and tissue fibrosis. Epigenetics is a fast-growing discipline, and a considerable number of important epigenetic studies in SSc have been published in the past few years that span histone post-translational modifications, DNA methylation, microRNAs and long non-coding RNAs. This Review describes the latest insights into genetic and epigenetic contributions to the pathogenesis of SSc and aims to provide an improved understanding of the molecular pathways that link inflammation and fibrosis. This knowledge will be of paramount importance for the development of medicines that are effective in treating or even reversing tissue fibrosis.

Interleukin-17 pathways in systemic sclerosis-associated fibrosis

Fibrosis is unregulated tissue repair that may cause impairment of organ function, especially in end-organ damage. Systemic sclerosis (SSc) is the prototype systemic fibrosing disorder. Classical targets for fibrosis in SSc like transforming growth factor Beta (TGF-β), Interleukin-6 (IL-6), and multiple tyrosine kinases, have not yielded therapeutic benefit. There is multitude of evidence from across different tissues like the heart, lung, skin, liver, colon, and, to some extent, the kidney, that interleukin-17 (IL-17) and its downstream pathways are strongly associated with the initiation and propagation of fibrosis. Data from scleroderma patients, as well as from animal models of SSc, mirror these findings. Interestingly, hitherto unknown to be related to IL-17, newer molecules like Programmed Death-protein1 (PD-1), the phosphatase SHP2, along with known signal transducers like signal transducer and activator of transcription (STAT3), have been recently shown to be involved in the pathogenesis of fibrosis. Related molecules include the intracellular signalling molecules Ras/Erk, mammalian target organ of rapamycin (mTOR), and complement components. The biology of these pathways has not yet been fully elucidated to predict regulatory mechanisms, redundancies, and potential off-target effects. All these need to be better understood in the context of each other, in an effort to arrive at the optimal target to modulate fibrosis.

IL-23 and dendritic cells: What are the roles of their mutual attachment in immune response and immunotherapy?

Interleukin-23 (IL-23) is a cytokine that is composed of the subunits p19 and p40, while its receptor (IL-23R) consists of two subunits, that is, IL-23Rα and IL-12Rβ1. The interaction between IL-23 and IL-23R is necessary for exerting cardinal biological effects upon certain cell types, including promotion of memory T cell proliferation and Th17 cell-mediated IL-17 secretion. Accordingly, dendritic cells (DCs) are one of the main sources for IL-23 secretion. Interestingly, IL-23R is also present on the DC plasma membrane, suggesting that IL-23 potentially acts on DCs via an autocrine manner. In this review, we have summarized a variety of IL-23-mediated effects on the intracellular signaling pathways such as Janus kinase 2, tyrosine kinase 2, signal transducer and activator of transcription (STAT), mitogen-activated protein kinase signaling, and so forth, which may underlie numerous processes such as DC maturation, antigen presentation, T cell proliferation/activation, and cytokine secretion, which may be implicated in many immune-related diseases through IL-23/DC interactions. Accordingly, these signaling pathways are extensively involved in the pathogenesis and progression of numerous diseases, including autoimmune disease (e.g., atopic dermatitis, asthma, and multiple sclerosis) and infection (e.g., bacterial, fungal, and viral infections). Taken together, they are potentially applicable to novel but promising strategies for treating numerous diseases associated with the mutual attachment of IL-23 and DCs.

Interleukin-17: Friend or foe in organ fibrosis

Fibrosis affects all vital organs accounting for a staggering 45% of deaths worldwide and no effective therapies are currently available. Unresolved inflammation triggers downstream signaling events that lead to organ fibrosis. In recent years, proinflammatory cytokine Interleukin-17 (IL-17) has been implicated in several chronic inflammatory diseases that often culminate in organ damage followed by impaired wound healing and fibrosis. In this review, we outline the contribution of the IL-17 in mediating fibrotic diseases in various organs. A comprehensive understanding of the inflammatory events, and particularly the details of IL-17 signaling in vivo, could be beneficial in designing new therapeutic or preventive approaches to treat fibrosis. Additionally, understanding organ-specific differences in IL-17 activity could lead to targeted therapies and help spare other organs from unwanted side effects.

Cerebrospinal fluid cytokine/chemokine/growth factor profiles in idiopathic hypertrophic pachymeningitis

Hypertrophic pachymeningitis (HP) is a rare neurologic disease causing inflammatory fibrous thickening of the brain and spinal dura mater. We investigated the cerebrospinal fluid cytokine profile of HP by measuring 28 cytokines/chemokines/growth factors with a multiplexed fluorescent immunoassay in 8 patients with HP (6 idiopathic, 1 IgG4-related, 1 anti-neutrophil cytoplasmic antibody-related), and 11 with other non-inflammatory neurologic diseases (OND). Interleukin (IL)-4, IL-5, IL-9, IL-10, TNF-α, and CXCL8/IL-8 levels were significantly higher in idiopathic HP (IHP) than OND. Cluster analyses disclosed two major clusters: one mainly consisted of IHP and the other of OND, suggesting a unique cytokine profile in IHP.

Macrophage migration inhibitory factor polymorphisms are a potential susceptibility marker in systemic sclerosis from southern Mexican population: association with MIF mRNA expression and cytokine profile

INTRODUCTION

Systemic sclerosis (SSc) is a complex autoimmune disease, characterized by microvascular lesions, autoimmunity, and fibrosis. It is suggested that MIF participates in the amplification of the proinflammatory process in SSc; moreover, the promoter polymorphisms - 794 CATT_5-8 (rs5844572) and - 173G>C (rs755622) in the MIF gene have been associated with an increase in MIF serum levels in several autoimmune diseases. The aim of this study was to analyze the relationship of the - 794 CATT_5-8 and - 173G>C MIF polymorphisms with mRNA expression, MIF serum levels, and the Th1/Th2/Th17 cytokine profile in SSc.

MATERIALS AND METHODS

A case-control study was carried out that included 50 patients with SSc and 100 control subjects (CS). Both polymorphisms were genotyped by PCR and PCR-RFLP. MIF levels were measured by ELISA kit. The cytokine profile and the MIF mRNA expression were quantified by BioPlex MagPix system and real-time PCR, respectively.

RESULTS

An association between the - 794 CATT₇ and - 173*C MIF alleles and the 7C haplotype with SSc susceptibility was found (p < 0.05). Also, the 7C haplotype was associated with increased MIF mRNA expression (p = 0.03) in SSc. In addition, an increase of IL-1β and IL-6 serum levels in SSc patients was found as well as a positive correlation between MIF serum levels and Th1 and Th17 cytokine profiles.

CONCLUSION

The MIF 7C haplotype is a susceptibility marker for SSc in the southern Mexican population and is associated with MIF mRNA expression. Moreover, there is a positive correlation between MIF serum levels and Th1 and Th17 inflammatory response in SSc.

Evaluation of the antifibrotic potency by knocking down SPARC, CCR2 and SMAD3

BACKGROUND

The genes of SPARC, CCR2, and SMAD3 are implicated in orchestrating inflammatory response that leads to fibrosis in scleroderma and other fibrotic disorders. The aim of the studies is to evaluate synergistic anti-fibrotic potency of the siRNAs of these genes.

METHODS

The efficacy of the siRNA-combination was evaluated in bleomycin-induced mouse fibrosis. The pathological changes of skin and lungs of the mice were assessed by hematoxylin and eosin and Masson's trichrome stains. The expression of inflammation and fibrosis associated genes and proteins in the tissues were assessed by real-time RT-PCR, RNA sequencing, Western blots and ELISA. Non-crosslinked fibrillar collagen was measured by the Sircol colorimetric assay.

FINDINGS

The applications of the combined siRNAs in bleomycin-induced mice achieved favorable anti-inflammatory and anti-fibrotic effects. Activation of fibroblasts was suppressed in parallel with inhibition of inflammation evidenced by reduced inflammatory cells and proinflammatory cytokines in the BALF and/or the tissues by the treatment. Aberrant expression of the genes normally expressed in fibroblasts, monocytes/ macrophage, endothelial and epithelial cells were significantly restrained after the treatment. In addition, transcriptome profiles indicated that some bleomycin-induced alterations of multiple biological pathways were recovered to varying degrees by the treatment.

INTERPRETATION

The application of the combined siRNAs of SPARC, CCR2, and SMAD3 genes ameliorated inflammation and fibrosis in bleomycin-induced mice. It systemically reinstated multiple biopathways, probably through controlling on different cell types including fibroblasts, monocytes/macrophages, endothelial cells and others. The multi-target-combined therapeutic approach examined herein may represent a novel and effective therapy for fibrosis.

IL-17 Receptor Signaling Negatively Regulates the Development of Tubulointerstitial Fibrosis in the Kidney

Chronic inflammation has an important role in the development and progression of most fibrotic diseases, for which no effective treatments exist. Tubulointerstitial fibrosis (TF) is characterized by irreversible deposition of fibrous tissue in chronic kidney diseases. Prolonged injurious stimuli and chronic inflammation regulate downstream events that lead to TF. In recent years, interleukin-17 (IL-17) has been strongly linked to organ fibrosis. However, the role of IL-17 receptor signaling in TF is an active area of debate. Using the unilateral ureteral obstruction (UUO) mouse model of TF, we show that IL-17 receptor A-deficient mice (Il17ra-/- ) exhibit increased TF in the obstructed kidney. Consequently, overexpression of IL-17 restored protection in mice with UUO. Reduced renal expression of matrix-degrading enzymes results in failure to degrade ECM proteins, thus contributing to the exaggerated TF phenotype in Il17ra -/- mice. We demonstrate that the antifibrotic kallikrein-kinin system (KKS) is activated in the obstructed kidney in an IL-17-dependent manner. Accordingly, Il17ra-/- mice receiving bradykinin, the major end-product of KKS activation, prevents TF development by upregulating the expression of matrix-degrading enzymes. Finally, we show that treatment with specific agonists for bradykinin receptor 1 or 2 confers renal protection against TF. Overall, our results highlight an intriguing link between IL-17 and activation of KKS in protection against TF, the common final outcome of chronic kidney conditions leading to devastating end-stage renal diseases.

Imbalance between T helper 17 and regulatory T cell subsets plays a significant role in the pathogenesis of systemic sclerosis

Systemic sclerosis (SSc) is a rare autoimmune disease that is characterized by fibrosis, inflammation, and vasculopathy of the skin and internal organs. The etiopathogenesis of SSc remains unclear. However, the pivotal role of T lymphocytes with an aberrant immune response in SSc is well established. Among T cells, IL-17-producing helper T (Th17) cell and regulatory T (Treg) cell subsets have recently been found to play crucial roles in SSc pathogenesis. Generally speaking, Th17 cell subsets up-regulate inflammation, fibrosis, and autoimmunity, which are present in SSc, while Treg cell subsets have an immunosuppressive function and resist the immunological performance of Th17 cells. Up-to-date evidence has pointed out that the imbalance and abnormal functions of Th17/Treg cells may contribute to SSc. Therefore, this review aims to summarize the current understanding of the vital cytokines and signaling pathways that are involved in Th17/Treg differentiation and functions, and their roles in the pathogenesis of SSc, thus providing novel insights about targeting the Th17/Treg balance as a potential therapy for SSc treatment in the near future.

An orally-active adiponectin receptor agonist mitigates cutaneous fibrosis, inflammation and microvascular pathology in a murine model of systemic sclerosis

The hallmarks of systemic sclerosis (SSc) are autoimmunity, microangiopathy and fibrosis. Skin fibrosis is accompanied by attrition of the dermal white adipose tissue layer, and alterations in the levels and function of adiponectin. Since these findings potentially implicate adiponectin in the pathogenesis of SSc, we employed a novel pharmacological approach to augment adiponectin signaling using AdipoRon, an orally active adiponectin receptor agonist. Chronic treatment with AdipoRon significantly ameliorated bleomycin-induced dermal fibrosis in mice. AdipoRon attenuated fibroblast activation, adipocyte-to-myofibroblast transdifferentiation, Th2/Th17-skewed polarization of the immune response, vascular injury and endothelial-to-mesenchymal transition within the lesional skin. In vitro, AdipoRon abrogated profibrotic responses elicited by TGF-β in normal fibroblasts, and reversed the inherently-activated profibrotic phenotype of SSc fibroblasts. In view of these broadly beneficial effects on all three cardinal pathomechanisms underlying the clinical manifestations of SSc, pharmacological augmentation of adiponectin signaling might represent a novel strategy for the treatment of SSc.

Serum interleukin-34 levels in patients with systemic sclerosis: Clinical association with interstitial lung disease

Interleukin (IL)-34 is a hematopoietic cytokine promoting proliferation and differentiation of macrophages. Because abnormal activation of macrophages is involved in the development of systemic sclerosis (SSc), we investigated serum IL-34 levels in patients with SSc. Serum IL-34 levels were significantly increased in diffuse cutaneous SSc compared with limited cutaneous SSc and healthy controls, while there were no significant differences between limited cutaneous SSc and healthy controls. In addition, SSc patients with increased serum IL-34 levels more often had interstitial lung disease (ILD) than those with normal levels. Moreover, in SSc patients, serum IL-34 levels negatively correlated with the percentage of predicted vital capacity, while they positively correlated with ground-glass opacity score and fibrotic score on chest computed tomography. Collectively, increased serum IL-34 levels were associated with greater frequency and severity of ILD in SSc patients. Serum IL-34 levels may be a useful serological marker for SSc-associated ILD.

Increased serum levels of adhesion molecules ICAM-1 and VCAM-1 in systemic sclerosis are not specific for pulmonary manifestations

Studies suggest elevated serum intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) levels may be markers of pulmonary arterial hypertension in systemic sclerosis (SSc-PAH). We sought to evaluate whether ICAM-1 and VCAM-1 levels are useful screening biomarkers for incident SSc-PAH. In this cross-sectional study, four groups were selected from the Australian Scleroderma Cohort Study: group 1 (n = 15) had definite PAH; group 2 (n = 19) had interstitial lung disease (ILD); group 3 (n = 30) were SSc-controls; and group 4 (n = 34) were healthy controls. Serum ICAM-1 and VCAM-1 levels were measured using the Millipore Milliplex MAP Human 2-Plex Panel. There were no differences in ICAM-1 levels in the PAH versus ILD group (263.0 ± 85.4 vs 380.4 ± 168.3 ng/mL, p = 0.136), SSc-controls (263.0 ± 85.4 vs 253.1 ± 98.0 ng/mL, p = 1.00), or healthy controls (263.0 ± 85.4 vs 201.8 ± 57.2 ng/mL, p = 0.093). Similarly, there were no differences in VCAM-1 level in PAH versus ILD groups (1476.2 ± 434.9 vs 1424.8 ± 527.6 ng/mL, p = 1.00) and SSc-controls (1476.2 ± 434.9 vs 1409.5 ± 341.1 ng/mL, p = 1.00). SSc subjects had significantly higher levels of ICAM-1 (297.4 ± 134.0 vs 201.8 ± 57.2 ng/mL, p < 0.0001) and VCAM-1 compared to healthy controls (1432.7 ± 427.4 vs 1125.6 ± 273.4 ng/mL, p < 0.0001). Neither ICAM-1 nor VCAM-1 is a specific screening biomarker of SSc-PAH. Instead, increased levels of these adhesion molecules in SSc, irrespective of pulmonary complications, suggest that they may play a role in SSc pathogenesis.

MicroRNA-17-92 is required for T-cell and B-cell pathogenicity in chronic graft-versus-host disease in mice

Chronic graft-versus-host disease (cGVHD) is characterized as autoimmune-like fibrosis and antibody production mediated by pathogenic T cells and B cells. MicroRNA-17-92 (miR-17-92) influences the survival, differentiation, and function of lymphocytes in cancer, infections, and autoimmunity. To determine whether miR-17-92 regulates T- and B-cell responses in cGVHD, we generated mice conditionally deficient for miR-17-92 in T cells, B cells, or both. Using murine models of allogeneic bone marrow transplantation, we demonstrate that expression of miR-17-92 in donor T and B cells is essential for the induction of both scleroderma and bronchiolitis obliterans in cGVHD. Mechanistically, miR-17-92 expressed in T cells not only enhances the differentiation of pathogenic T helper 1 (Th1) and Th17 cells, but also promotes the generation of follicular Th cells, germinal center (GC) B cells, and plasma cells. In B cells, miR-17-92 expression is required for autoantibody production and immunoglobulin G deposition in the skin. Furthermore, we evaluated a translational approach using antagomirs specific for either miR-17 or miR-19, key members in miR-17-92 cluster. In a lupus-like cGVHD model, systemic administration of anti-miR-17, but not anti-miR-19, alleviates clinical manifestations and proteinuria incidence in recipients through inhibiting donor lymphocyte expansion, B-cell activation, and GC responses. Blockade of miR-17 also ameliorates skin damage by reducing Th17 differentiation in a scleroderma-cGVHD model. Taken together, our work reveals that miR-17-92 is required for T-cell and B-cell differentiation and function, and thus for the development of cGVHD. Furthermore, pharmacological inhibition of miR-17 represents a potential therapeutic strategy for the prevention of cGVHD.

Fli1-haploinsufficient dermal fibroblasts promote skin-localized transdifferentiation of Th2-like regulatory T cells

Background

Friend leukemia virus integration 1 (Fli1) deficiency, a predisposing factor of systemic sclerosis (SSc), induces SSc-like phenotypes in various cell types. A recent study demonstrated the transdifferentiation of T helper type 2 cell (Th2)-like regulatory T cells (Tregs) in SSc lesional skin through interleukin (IL)-33 produced by fibroblasts. Therefore, we investigated the role of Fli1 deficiency in dermal fibroblast-mediated transdifferentiation of Tregs.

Methods

Cytokine expression was assessed in Tregs by flow cytometry and in skin samples and cultivated cells by immunostaining, immunoblotting, and/or qRT-PCR. Fli1 binding to the target gene promoters was examined by chromatin immunoprecipitation. Murine dermal fibroblasts and Tregs were cocultured with or without blocking antibodies against target cytokines.

Results

Th2- and Th17-like cell proportions in skin-homing Tregs were increased in bleomycin-treated Fli1^+/− mice compared with bleomycin-treated wild-type mice, whereas Th1-, Th2-, and Th17-like cell proportions in splenic Tregs were comparable. Fli1^+/− fibroblasts overproduced IL-33 and IL-6, in particular IL-33, and Fli1 occupied the IL33 and IL6 promoters in dermal fibroblasts. Importantly, the IL-4-producing cell proportion was significantly higher in wild-type Tregs cocultured with Fli1^+/− fibroblasts than in those cocultured with wild-type fibroblasts, which were canceled by neutralizing anti-IL-33 antibody. Under the same coculture condition, an increased tendency of IL-17A-producing cell proportion, which was possibly mediated by IL-6, was evident.

Conclusions

Fli1 haploinsufficiency increases the proportions of Th2- and Th17-like Tregs in bleomycin-induced profibrotic skin conditions, in which IL-33-producing dermal fibroblasts contribute to Th2-like Treg transdifferentiation, suggesting a critical role of Fli1 deficiency in the interaction of dermal fibroblasts with immune cells in pathological skin fibrosis.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1521-3) contains supplementary material, which is available to authorized users.

What can we learn from Fli1-deficient mice, new animal models of systemic sclerosis?

Systemic sclerosis is a complex multifactorial disease characterized by autoimmunity, vasculopathy, and selective organ fibrosis. A series of genetic and epidemiological studies have demonstrated that environmental influences play a central role in the onset of systemic sclerosis, while genetic factors determine the susceptibility to and the severity of this disease. Therefore, the identification of predisposing factors related to environmental influences would provide us with an informative clue to better understand the pathological process of this disease. Based on this concept, the deficiency of transcription factor Friend leukemia virus integration 1, which is epigenetically suppressed in systemic sclerosis, seems to be a potential candidate acting as the predisposing factor of this disease. Indeed, Fli1-mutated mice serve as a set of useful disease models to disclose the complex pathology of systemic sclerosis. This article overviews the recent advancement in systemic sclerosis animal models associated with Friend leukemia virus integration 1 deficiency.