Regulatory T Cells in Systemic Sclerosis

In recent years, accumulating evidence suggest that regulatory T cells (Tregs) are of paramount importance for the maintenance of immunological self-tolerance and immune homeostasis, even though they represent only about 5–10% of the peripheral CD4+ T cells in humans. Their key role is indeed supported by the spontaneous development of autoimmune diseases after Tregs depletion in mice. Moreover, there is also a growing literature that investigates possible contribution of Tregs numbers and activity in various autoimmune diseases. The contribution of Tregs in autoimmune disease has opened up a new therapeutic avenue based on restoring a healthy balance between Tregs and effector T-cells, such as Treg-based cellular transfer or low-dose IL-2 modulation. These therapies hold the promise of modulating the immune system without immunosuppression, while several issues regarding efficacy and safety need to be addressed. Systemic sclerosis (SSc) is an orphan connective tissue disease characterized by extensive immune abnormalities but also microvascular injury and fibrosis. Recently, data about the presence and function of Tregs in the pathogenesis of SSc have emerged although they remain scarce so far. First, there is a general agreement in the medical literature with regard to the decreased functional ability of circulating Tregs in SSc. Second the quantification of Tregs in patients have led to contradictory results; although the majority of the studies report reduced frequencies, there are conversely some indications suggesting that in case of disease activity circulating Tregs may increase. This paradoxical situation could be the result of a compensatory, but inefficient, amplification of Tregs in the context of inflammation. Nevertheless, these results must be tempered with regards to the heterogeneity of the studies for the phenotyping of the patients and of the most importance for Tregs definition and activity markers. Therefore, taking into account the appealing developments of Tregs roles in autoimmune diseases, together with preliminary data published in SSc, there is growing interest in deciphering Tregs in SSc, both in humans and mice models, to clarify whether the promises obtained in other autoimmune diseases may also apply to SSc

Targeting CD226/DNAX accessory molecule-1 (DNAM-1) in collagen-induced arthritis mouse models

International audienceBackground: Genetic studies have pointed out that CD226 variants, encoding DNAM-1, could be associated with susceptibility to rheumatoid arthritis. Therefore, we aimed to determine the influence of DNAM-1 on the development of arthritis using the collagen-induced arthritis (CIA) mouse model. Methods: CIA was induced in mice on a DBA/1 background, treated in parallel with a DNAM-1 neutralizing monoclonal antibody, a control IgG and PBS, respectively. CIA was also induced in mice deficient for DNAM-1(dnam1−/−) and control dnam-1+/+ mice on a C57/BL6 background. Mice were monitored for clinical and ultrasound signs of arthritis. Histological analysis was performed to search for inflammatory infiltrates and erosions. The Mann–Whitney U test for non-related samples was used for statistical analysis. Results: There was a non-significant trend for a less arthritic phenotype in mice receiving anti-DNAM-1 mAb at both clinical, ultrasound and histological assessments. But, we did not observe any difference between dnam1+/+ and dnam1−/− mice for incidence nor severity of clinical arthritis. Histological analysis revealed inflammatory scores similar in both groups, without evidence of erosion. Collagen antibodies levels were similar in all mice, confirming immunization with collagen. Conclusion: Despite some clues suggesting a role of DNAM-1 in arthritis, these complementary approaches demonstrate no contribution of CD226/DNAM-1 in the arthritic phenotype. These results contrast with previous studies showing a role in vivo of DNAM-1 in some autoimmune disorders

Systemic sclerosis-associated pulmonary hypertension: why disease-specific composite endpoints are needed

Pulmonary arterial hypertension (PAH) is a serious complication of systemic sclerosis (SSc). In clinical trials PAH-SSc has been grouped with other forms, including idiopathic PAH. The primary endpoint for most pivotal studies was improvement in exercise capacity. However, composite clinical endpoints that better reflect long-term outcome may be more meaningful. We discuss potential endpoints and consider why the same measures may not be appropriate for both idiopathic PAH and PAH-SSc due to inherent differences in clinical outcome and management strategies of these two forms of PAH. Failure to take this into account may compromise progress in managing PAH in SSc

The transcription factor JunD mediates transforming growth factor β-induced fibroblast activation and fibrosis in systemic sclerosis

Objectives: Transforming growth factor β (TGFβ) has been identified as a key player in fibrotic diseases. However, the molecular mechanisms by which TGFβ activates fibroblasts are incompletely understood. Here, the role of JunD, a member of the activator protein 1 (AP-1) family of transcription factors, as a downstream mediator of TGFβ signalling in systemic sclerosis (SSc), was investigated. Methods: The expression of JunD was analysed by real-time PCR, immunofluorescence, western blotting and immunohistochemistry. The canonical Smad pathway was specifically targeted by small interfering (si)RNA. The expression of extracellular matrix proteins in JunD deficient (JunD−/−) fibroblasts was analysed by real-time PCR and hydroxyproline assays. The mouse model of bleomycin-induced dermal fibrosis was used to assess the role of JunD in experimental fibrosis. Results: JunD was overexpressed in SSc skin and in cultured fibroblasts in a TGFβ dependent manner. The expression of JunD colocalised with pSmad 3 in fibrotic skin and silencing of Smad 3 or Smad 4 by siRNA prevented the induction of JunD by TGFβ. JunD−/− fibroblasts were less responsive to TGFβ and released less collagen upon stimulation with TGFβ. Moreover, JunD−/− mice were protected from bleomycin-induced fibrosis with reduced dermal thickening, decreased myofibroblast counts and lower collagen content of lesional skin. Conclusions: These data demonstrate that JunD is overexpressed in SSc and that JunD is a mediator of the profibrotic effects of TGFβ. Considering that inhibitors of AP-1 signalling have recently been developed and are available for clinical trials in SSc, these findings may have translational implications

Tribbles homologue 3 stimulates canonical TGF-β signalling to regulate fibroblast activation and tissue fibrosis

Objectives: Tribbles homologue 3 (TRB3) is a pseudokinase that modifies the activation of various intracellular signalling pathways to control fundamental processes extending from mitosis and cell activation to apoptosis and modulation of gene expression. Here, we aimed to analyse the role of TRB3 in fibroblast activation in systemic sclerosis (SSc). Methods: The expression of TRB3 was quantified by quantitative PCR, western blot and immunohistochemistry. The role of TRB3 was analysed in cultured fibroblasts and in experimental fibrosis using small interfering RNA (siRNA)-mediated knockdown and overexpression of TRB3. Results: TRB3 expression was increased in fibroblasts of patients with SSc and in murine models of SSc in a transforming growth factor-β (TGF-β)/Smad-dependent manner. Overexpression of TRB3 stimulated canonical TGF-β signalling and induced an activated phenotype in resting fibroblasts. In contrast, knockdown of TRB3 reduced the profibrotic effects of TGF-β and decreased the collagen synthesis. Moreover, siRNA-mediated knockdown of TRB3 exerted potent antifibrotic effects and ameliorated bleomycin as well as constitutively active TGF-β receptor I-induced fibrosis with reduced dermal thickening, decreased hydroxyproline content and impaired myofibroblast differentiation. Conclusions: The present study characterises TRB3 as a novel profibrotic mediator in SSc. TGF-β induces TRB3, which in turn activates canonical TGF-β/Smad signalling and stimulates the release of collagen, thereby inducing a positive feedback loop that may contribute to aberrant TGF-β signalling in SSc

S100A4 amplifies TGF-β-induced fibroblast activation in systemic sclerosis

Objectives S100A4 is a calcium binding protein with regulatory functions in cell homeostasis, proliferation and differentiation that has been shown to promote cancer progression and metastasis. In the present study, we evaluated the role of S100A4 in fibroblast activation in systemic sclerosis (SSc). Methods The expression of S100A4 was analysed in human samples, murine models of SSc and in cultured fibroblasts by real-time PCR, immunohistochemistry and western blot. The functional role of S100A4 was evaluated using siRNA, overexpression, recombinant protein and S100A4 knockout (S100A4−/−) mice. Transforming growth factor β (TGF-β) signalling was assessed by reporter assays, staining for phosphorylated Smad2/3 and analyses of target genes. Results The expression of S100A4 was increased in SSc skin and in experimental fibrosis in a TGF-β/Smad-dependent manner. Overexpression of S100A4 or stimulation with recombinant S100A4 induced an activated phenotype in resting normal fibroblasts. In contrast, knockdown of S100A4 reduced the pro-fibrotic effects of TGF-β and decreased the release of collagen. S100A4−/− mice were protected from bleomycin-induced skin fibrosis with reduced dermal thickening, decreased hydroxyproline content and lower myofibroblast counts. Deficiency of S100A4 also ameliorated fibrosis in the tight-skin-1 (Tsk-1) mouse model. Conclusions We characterised S100A4 as a downstream mediator of the stimulatory effects of TGF-β on fibroblasts in SSc. TGF-β induces the expression of S100A4 to stimulate the release of collagen in SSc fibroblasts and induce fibrosis. Since S100A4 is essentially required for the pro-fibrotic effects of TGF-β and neutralising antibodies against S100A4 are currently evaluated, S100A4 might be a candidate for novel antifibrotic therapies

Soluble CD163 as a Potential Biomarker in Systemic Sclerosis

Objective. To evaluate the performance of serum and urinary sCD163 concentrations as possible biomarker in systemic sclerosis (SSc). Methods. Urine and serum samples were obtained from SSc patients and age- and sex-matched controls. Serum and urinary sCD163 concentrations were measured by commercially available ELISA kit. SSc patients were assessed following international guidelines. Cross-sectional analyses were performed. Results. Two hundred and three SSc patients were included. The control group consisted of 47 age- and sex-matched patients having noninflammatory diseases, mainly osteoporosis. Serum sCD163 levels were significantly higher in SSc patients compared with controls (mean ± SD: 529 ± 251 versus 385 ± 153 ng/mL; p<0.001). Urinary sCD163 concentrations were higher in SSc patients than controls, but this did not reach significance (236 ± 498 versus 176 ± 173 ng/mg uCr; p=0.580). The sCD163 concentrations were not associated with clinical, laboratory, and instrumental characteristics of SSc patients. Conclusion. To our knowledge, this is the first evaluation of both serum and urinary sCD163 levels in SSc. Our results show a significant difference for sera values that should be prioritized for further studies as compared to urinary measurements. Our results further support that the M2 macrophages/CD163 signaling system may play a role in the pathogenesis of SSc, although we could not identify a subset of SSc patients with higher concentrations

Soluble CD163 as a Potential Biomarker in Systemic Sclerosis

Objective. To evaluate the performance of serum and urinary sCD163 concentrations as possible biomarker in systemic sclerosis (SSc). Methods. Urine and serum samples were obtained from SSc patients and age- and sex-matched controls. Serum and urinary sCD163 concentrations were measured by commercially available ELISA kit. SSc patients were assessed following international guidelines. Cross-sectional analyses were performed. Results. Two hundred and three SSc patients were included. The control group consisted of 47 age- and sex-matched patients having noninflammatory diseases, mainly osteoporosis. Serum sCD163 levels were significantly higher in SSc patients compared with controls (mean ± SD: 529 ± 251 versus 385 ± 153 ng/mL; p<0.001). Urinary sCD163 concentrations were higher in SSc patients than controls, but this did not reach significance (236 ± 498 versus 176 ± 173 ng/mg uCr; p=0.580). The sCD163 concentrations were not associated with clinical, laboratory, and instrumental characteristics of SSc patients. Conclusion. To our knowledge, this is the first evaluation of both serum and urinary sCD163 levels in SSc. Our results show a significant difference for sera values that should be prioritized for further studies as compared to urinary measurements. Our results further support that the M2 macrophages/CD163 signaling system may play a role in the pathogenesis of SSc, although we could not identify a subset of SSc patients with higher concentrations

Sex influence on outcomes of patients with systemic sclerosis-associated interstitial lung disease: an EUSTAR database analysis

OBJECTIVE Interstitial lung disease (ILD) is the leading cause of morbidity/mortality in systemic sclerosis (SSc). We aimed to study investigate the impact of sex on SSc-ILD. METHODS EUSTAR SSc patients with radiological-confirmed ILD and available %predicted forced vital capacity(%pFVC) were included. Demographics and disease features were recorded. Change in %pFVC over 12±6 months (cohort 1) was classified into stable (≤4%), mild (5-9%) and large progression (≥10%). In those with 2-year longitudinal %pFVC (cohort 2), %pFVC change at each 12±6 months interval was calculated. Logistic regression analyses (OR and 95%CI) and Cox proportional hazards models adjusted for age and %pFVC were applied. RESULTS 1136 male and 5253 female SSc-ILD patients were identified. Males were significantly younger, had a shorter disease duration, higher prevalence of CRP elevation, were had frequently a diffuse cutaneous involvement. In cohort 1(1655 females and 390 males), a higher percentage of males had stable ILD (74.4% versus 69.4%, p = 0.056). In multivariable analysis, disease duration and %pFVC(OR 0.99,0.98-0.99; 0.97,0.95-0.99) in males and age, %pFVC and anti-centromere(OR 1.02,1.00-1.04; 0.97,0.96-0.98; 0.39,0.245-0.63) in females were associated with large progression. The 1-year mortality rate was higher in males (5.1% versus 2.5%, p = 0.013). In cohort 2(849 females and 209 males), a higher percentage of females showed periods of large progression (11.7% versus 7.7%, p = 0.023), the percentage of patients with 0, 1 or 2 periods of worsening was not different. The overall death rate was 30.9% for males and 20.4% in females (p < 0.001). At survival analysis, male sex was a predictor of mortality (OR 1.95, 1.66-2.28). CONCLUSIONS Male SSc-ILD patients have a poorer prognosis and sex-specific predictors exist in SSc-ILD

JAK inhibitors and risk of major cardiovascular events or venous thromboembolism: a self-controlled case series study

PURPOSE: JAK-inhibitors (JAK-i) might be associated with venous (VTE) and arterial thromboembolic events (ATE). To evaluate the association between JAK-i and the risk of VTE and ATE. METHODS: A self-controlled case series was performed using data from the nationwide French healthcare insurance system database SNDS. We included all patients treated with JAK-i (baricitinib or tofacitinib), and having presented at least one VTE or ATE between November 1, 2017 and June 30, 2019. Associations were estimated using the incident rate ratio (IRR). Two post-exposure periods (until day 30 and until day 60) were individualized. RESULTS: Among 5870 patients with JAK-i dispensing, 92 had an incident VTE or ATE within the study period. Their median age at JAK-i initiation was 65.7 years [IQR: 56.1-75.8] and 65.2% were female (n = 60). Before event incidence, 65.2% (n = 60) received baricitinib, 32.6% (n = 30) tofacitinib and 2.2% (n = 2) had both medications. Moreover, 41.3% (n = 38) presented a VTE and 58.7% (n = 54) an ATE. The median time-to-onset after JAK-i initiation was 4.6 months [IQR: 2.5-9.2] for VTE and 6.1 months [IQR: 3.0-8.5] for ATE. An IRR of 8.27 (95% CI 3.41-20.04) for VTE was detected during JAK-i treatment and remained increased over the 30-day period of post-exposure (6.52 [2.02-21.11]). An IRR of 9.27 (3.68-23.34) was also found for ATE, which remained increased over the 30-day period of post-exposure (10.12 [3.27-31.37]). No increased risk was detected during long-term post-exposure for either VTE or ATE. CONCLUSIONS: This study shows evidence of an increased risk of VTE and ATE associated with the use of baricitinib and tofacitinib