Targeting Costimulatory Pathways in Systemic Sclerosis

Systemic sclerosis (SSc) is an autoimmune T-cell disease that is characterized by pathological fibrosis of the skin and internal organs. SSc is considered a prototype condition for studying the links between autoimmunity and fibrosis. Costimulatory pathways such as CD28/CTLA-4, ICOS-B7RP1, CD70-CD27, CD40-CD154, or OX40-OX40L play an essential role in the modulation of T-cell and inflammatory immune responses. A growing body of evidence suggests that T-cell costimulation signals might be implicated in the pathogenesis of SSc. CD28, CTLA-4, ICOS, and OX40L are overexpressed in patients with SSc, particularly in patients with cutaneous diffuse forms. In pre-clinical models of SSc, T-cell costimulation blockade with abatacept (CTLA-4-Ig) prevented and induced the regression of inflammation-driven dermal fibrosis, improved digestive involvement, prevented lung fibrosis, and attenuated pulmonary hypertension in complementary models of SSc. Likewise, potent anti-fibrotic effects were seen with the blockade of OX40L by reducing the infiltration of inflammatory cells into lesional tissues leading to decreased fibroblast activation. Concerning clinical effects, a preliminary observational study suggested some effectiveness of abatacept on inflammatory joint involvement, whereas clinical improvement of skin fibrosis was observed in a small placebo-controlled randomized trial. Currently there is one ongoing phase II clinical trial assessing the efficacy of abatacept in SSc (ASSET trial, NCT02161406). Overall, given the lack of available effective agents and the known toxic effects of immunosuppressive agents approved for use in SSc, costimulatory pathways offer the advantage of a targeted approach to costimulatory signals and potentially a better safety profile

Nifedipine decreases sVCAM-1 concentrations and oxidative stress in systemic sclerosis but does not affect the concentrations of vascular endothelial growth factor or its soluble receptor 1

Microvascular injury, oxidative stress, and impaired angiogenesis are prominent features of systemic sclerosis (SSc). We compared serum markers of these phenomena at baseline and after treatment with nifedipine in SSc patients. Forty successive SSc patients were compared with 20 matched healthy subjects. All SSc patients stopped taking calcium-channel blockers 72 hours before measurements. Twenty SSc patients were also examined after 14 days of treatment with nifedipine (60 mg/day). Quantitative ELISA was used to measure the serum concentrations of vascular endothelial growth factor (VEGF), soluble VEGF receptor 1 (sVEGFR-1), soluble vascular cell adhesion molecule 1 (sVCAM-1), carbonyl residues, and advanced oxidation protein products (AOPP). The median concentrations of VEGF, sVEGFR-1, sVCAM-1, carbonyl residues, and AOPP were significantly higher in SSc patients than in healthy subjects at baseline. A correlation was found between VEGF concentration and carbonyl residue concentration (r = 0.43; P = 0.007). Nifedipine treatment led to a significant decrease in concentrations of sVCAM-1, carbonyl residues, and AOPP but did not affect concentrations of VEGF and sVEGFR-1. Nifedipine treatment ameliorated endothelium injury in patients with SSc, as shown by the concentrations of adhesion molecules and oxidative damage markers. The fact that VEGF and sVEGFR-1 concentrations were not changed whereas oxidative stress was ameliorated by nifedipine is consistent with the hypothesis that VEGF signalling is impaired in SSc. However, more experimental evidence is needed to determine whether the VEGF pathway is intrinsically defective in SSc

Increased frequency of circulating Th22 in addition to Th17 and Th2 lymphocytes in systemic sclerosis: association with interstitial lung disease

International audienceABSTRACT: INTRODUCTION: T cell abnormalities have been associated with the pathogenesis of systemic sclerosis (SSc). Recently, besides T helper (Th)17 cells the Th22 subset has been identified in humans. Our purpose was to investigate the pattern of cytokines produced and chemokine-receptors expressed by peripheral blood (PB) Th cells in SSc and healthy donors (HD) focusing on cells producing interleukin (IL)-17 and IL-22 and to identify specific clinical associations. METHODS: Clinical data and peripheral blood were collected in 33 SSc individuals and 29 HD. IL-17A, IL-22, interferon gamma (IFN-gamma, IL-4 production, the chemokine receptors CCR4, CCR6, CCR10, CXCR3 expression and the CD161 Th17 cell marker were assessed by multiparametric flow cytometry in PB CD4+ T cells. Intracellular cytokine accumulation was further investigated in CD4+ T cells expanded in vitro for 7 days. RESULTS: The frequency of Th22, Th17, Th2 but not Th1 cells was significantly increased in SSc individuals compared to HD. The percentage of CD161+CD4+ T cells was increased in SSc and correlated with the percentage of IL-17A producing cells. Moreover, the expression of the skin- and lung-homing chemokine receptor CCR6 correlated with the frequency of IL-22 and IL-17A-producing cells in SSc but not in HD. Finally, SSc interstitial lung disease (ILD) was strongly associated with higher numbers of IL-22 and, to a lesser extent, IL-17A-producing cells. CONCLUSIONS: IL-22 and IL-17A-producing T cells with skin- and lung-homing capabilities are characteristically increased in SSc. These findings support the hypothesis that Th22 in addition to Th17 cells may be involved in pathological processes leading to SSc. While the association between IL-22 producing cells and ILD needs to be assessed in larger cohorts of patients, the increased frequency of Th22 cells appears to be a useful novel biomarker in SSc

Nifedipine protects against overproduction of superoxide anion by monocytes from patients with systemic sclerosis

We have reported previously that dihydropyridine-type calcium-channel antagonists (DTCCA) such as nifedipine decrease plasma markers of oxidative stress damage in systemic sclerosis (SSc). To clarify the cellular basis of these beneficial effects, we investigated the effects in vivo and in vitro of nifedipine on superoxide anion (O(2)(•-)) production by peripheral blood monocytes. We compared 10 healthy controls with 12 patients with SSc, first after interruption of treatment with DTCCA and second after 2 weeks of treatment with nifedipine (60 mg/day). O(2)(•- )production by monocytes stimulated with phorbol myristate acetate (PMA) was quantified by the cytochrome c reduction method. We also investigated the effects in vitro of DTCCA on O(2)(•- )production and protein phosphorylation in healthy monocytes and on protein kinase C (PKC) activity using recombinant PKC. After DTCCA had been washed out, monocytes from patients with SSc produced more O(2)(•- )than those from controls. Nifedipine treatment considerably decreased O(2)(•- )production by PMA-stimulated monocytes. Treatment of healthy monocytes with nifedipine in vitro inhibited PMA-induced O(2)(•- )production and protein phosphorylation in a dose-dependent manner. Finally, nifedipine strongly inhibited the activity of recombinant PKC in vitro. Thus, the oxidative stress damage observed in SSc is consistent with O(2)(•- )overproduction by primed monocytes. This was decreased by nifedipine treatment both in vivo and in vitro. This beneficial property of nifedipine seems to be mediated by its cellular action and by the inhibition of PKC activity. This supports the hypothesis that this drug could be useful for the treatment of diseases associated with oxidative stress

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

Raynaud phenomenon and digital ulcers in systemic sclerosis

Raynaud phenomenon is a symptom complex caused by impaired digital perfusion and can occur as a primary phenomenon or secondary to a wide range of underlying causes. Raynaud phenomenon occurs in virtually all patients with systemic sclerosis (SSc) and is often the earliest clinical manifestation to occur. Careful assessment is required in patients with Raynaud phenomenon to avoid missing secondary causes such as SSc. Digital ulcers are a painful and disabling visible manifestation of digital vascular injury in patients with SSc. Progress has been made in the classification and assessment of digital ulcers and in understanding ulcer pathogenesis, and there are a wide range of treatments available to both prevent and heal digital ulcers, some of which are also used in Raynaud phenomenon management. In this Review, the assessment of patients with Raynaud phenomenon is discussed, including ‘red flags’ that are suggestive of SSc. The pathogenesis, classification and assessment of SSc-associated digital ulcers are also covered, alongside an overview of management approaches for SSc-associated Raynaud phenomenon and digital ulcers. Finally, unmet needs are discussed and the concept of a unified vascular phenotype in which therapies that affect the vasculature to support disease modification strategies is introduced

Type 1 interferon activation in systemic sclerosis: a biomarker, a target or the culprit

PURPOSE OF REVIEW: Activation of the type 1 interferon (T1 IFN) pathway has been implicated in the pathogenesis of systemic sclerosis (SSc) by an increasing number of studies, most of which share key findings with similar studies in systemic lupus erythematosus (SLE). Here we will focus on the evidence for T1 IFN activation and dysregulation in SSc, and the rationale behind targeting the pathway going forward. RECENT FINDINGS: An increased expression and activation of T1 IFN-regulated genes has been shown to be present in a significant proportion of SSc patients. TI IFN activation markers have been found to predict and correlate with response to immunosuppressive treatment as well as severity of organ involvement. As inhibition of the IFN-α receptor has been proven to be effective in active SLE, benefit may be seen in targeting the IFN pathway in SSc. SUMMARY: The role played by T1 IFN and its regulatory genes in SSc is becoming increasingly evident and strikingly similar to the role observed in SLE. This observation, together with the benefit of type 1 IFN targeting in SLE, supports the notion of a potential therapeutic benefit in targeting T1 IFN in 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