Background IgG4-related disease (IgG4-RD) is a systemic condition of unknown etiology, characterized by highly fibrotic lesions with dense lymphoplasmacytic infiltrates. CD4+ T cells constitute the major inflammatory cell population in IgG4-RD lesions. Objective We used an unbiased approach to characterize CD4+ T cell subsets in IgG4-RD subjects based on their clonal expansion and their ability to infiltrate affected tissue sites. Methods We used flow cytometry to identify CD4+ effector/memory T cells (TEM) in a cohort of 101 IgG4-related disease (IgG4-RD) patients. These expanded cells were characterized by gene expression analysis and flow cytometry. Next-generation sequencing of the T cell receptor β chain gene was performed on CD4+SLAMF7+ CTLs and CD4+GATA3+ TH2 cells in a subset of patients to identify their clonality. Tissue infiltration by specific T cells was examined using quantitative multi-color imaging. Results CD4+ effector/memory T cells with a cytolytic phenotype were expanded in IgG4-RD patients. Next-generation sequencing revealed prominent clonal expansions of these CD4+CTLs but not CD4+GATA3+ memory TH2 cells in subjects with IgG4-RD. The dominant T cells infiltrating a range of inflamed IgG4-RD tissue sites were clonally-expanded CD4+CTLs that expressed SLAMF7, granzyme A, IL-1β, and TGF-β1. Clinical remission induced by rituximab-mediated B cell depletion was associated with a reduction in disease-associated CD4+ CTLs Conclusions IgG4-RD is prominently linked to clonally-expanded, IL-1β, and TGF- β1 secreting, CD4+ CTLs in peripheral blood as well as in inflammatory tissue lesions. These active, terminally-differentiated, cytokine-secreting effector CD4+ T cells are now linked to a human disease characterized by chronic inflammation and fibrosis.

Objective T cells play a key role in the pathogenesis of early systemic sclerosis. This study was undertaken to assess the safety and efficacy of abatacept in patients with diffuse cutaneous systemic sclerosis (dcSSc). Methods In this 12‐month, randomized, double‐blind, placebo‐controlled trial, participants were randomized 1:1 to receive either subcutaneous abatacept 125 mg or matching placebo, stratified by duration of dcSSc. Escape therapy was allowed at 6 months for worsening disease. The coprimary end points were change in the modified Rodnan skin thickness score (MRSS) compared to baseline and safety over 12 months. Differences in longitudinal outcomes were assessed according to treatment using linear mixed models, with outcomes censored after initiation of escape therapy. Skin tissue obtained from participants at baseline was classified into intrinsic gene expression subsets. Results Among 88 participants, the adjusted mean change in the MRSS at 12 months was −6.24 units for those receiving abatacept and −4.49 units for those receiving placebo, with an adjusted mean treatment difference of −1.75 units (P = 0.28). Outcomes for 2 secondary measures (Health Assessment Questionnaire disability index and a composite measure) were clinically and statistically significantly better with abatacept. The proportion of subjects in whom escape therapy was needed was higher in the placebo group relative to the abatacept group (36% versus 16%). In the inflammatory and normal‐like skin gene expression subsets, decline in the MRSS over 12 months was clinically and significantly greater in the abatacept group versus the placebo group (P < 0.001 and P = 0.03, respectively). In the abatacept group, adverse events occurred in 35 participants versus 40 participants in the placebo group, including 2 deaths and 1 death, respectively. Conclusion In this phase II trial, abatacept was well‐tolerated, but change in the MRSS was not statistically significant. Secondary outcome measures, including gene expression subsets, showed evidence in support of abatacept. These data should be confirmed in a phase III trial.

RationaleClinical trial design in interstitial lung diseases (ILDs) has been hampered by lack of consensus on appropriate outcome measures for reliably assessing treatment response. In the setting of connective tissue diseases (CTDs), some measures of ILD disease activity and severity may be confounded by non-pulmonary comorbidities.MethodsThe Connective Tissue Disease associated Interstitial Lung Disease (CTD-ILD) working group of Outcome Measures in Rheumatology—a non-profit international organisation dedicated to consensus methodology in identification of outcome measures—conducted a series of investigations which included a Delphi process including >248 ILD medical experts as well as patient focus groups culminating in a nominal group panel of ILD experts and patients. The goal was to define and develop a consensus on the status of outcome measure candidates for use in randomised controlled trials in CTD-ILD and idiopathic pulmonary fibrosis (IPF).ResultsA core set comprising specific measures in the domains of lung physiology, lung imaging, survival, dyspnoea, cough and health-related quality of life is proposed as appropriate for consideration for use in a hypothetical 1-year multicentre clinical trial for either CTD-ILD or IPF. As many widely used instruments were found to lack full validation, an agenda for future research is proposed.ConclusionIdentification of consensus preliminary domains and instruments to measure them was attained and is a major advance anticipated to facilitate multicentre RCTs in the field.

Objective. Scleroderma (systemic sclerosis [SSc]), is characterized by progressive multiorgan fibrosis. We recently implicated lysophosphatidic acid (LPA) in the pathogenesis of pulmonary fibrosis. The purpose of the present study was to investigate the roles of LPA and two of its receptors, LPA 1 and LPA 2 , in dermal fibrosis in a mouse model of SSc.Methods. Wild type (WT), and LPA 1 -knockout (KO) and LPA 2 -KO mice were injected subcutaneously with bleomycin or phosphate buffered saline (PBS) once daily for 28 days. Dermal thickness, collagen content, and numbers of cells positive for ␣-smooth muscle actin (␣-SMA) or phospho-Smad2 were determined in bleomycin-injected and PBS-injected skin. In separate experiments, a novel selective LPA 1 antagonist AM095 or vehicle alone was administered by oral gavage to C57BL/6 mice that were challenged with 28 daily injections of bleomycin or PBS. AM095 or vehicle treatments were initiated concurrently with, or 7 or 14 days after, the initiation of bleomycin and PBS injections and continued to the end of the experiments. Dermal thickness and collagen content were determined in injected skin.Results. The LPA 1 -KO mice were markedly resistant to bleomycin-induced increases in dermal thickness and collagen content, whereas the LPA 2 -KO mice were as susceptible as the WT mice. Bleomycin-induced increases in dermal ␣-SMA؉ and phospho-Smad2؉ cells were abrogated in LPA 1 -KO mice. Pharmacologic antagonism of LPA 1 with AM095 significantly attenuated bleomycin-induced dermal fibrosis when administered according to either a preventive regimen or two therapeutic regimens.Conclusion. These results suggest that LPA/LPA 1 pathway inhibition has the potential to be an effective new therapeutic strategy for SSc, and that LPA 1 is an attractive pharmacologic target in dermal fibrosis.

Interstitial lung disease (ILD) is a challenging clinical entity associated with multiple connective tissue diseases, and is a significant cause of morbidity and mortality. Effective therapies for connective tissue disease-associated interstitial lung disease (CTD-ILD) are still lacking. Multidisciplinary clinics dedicated to the early diagnosis and improved management of patients with CTD-ILD are now being established. There is rapid progress in understanding and identifying the effector cells, the proinflammatory and profibrotic mediators, and the pathways involved in the pathogenesis of CTD-ILD. Serum biomarkers may provide new insights as risk factors for pulmonary fibrosis and as measures of disease progression. Despite these recent advances, the management of patients with CTD-ILD remains suboptimal. Further studies are therefore urgently needed to better understand these conditions, and to develop effective therapeutic interventions.

ObjectivesDetermine global skin transcriptome patterns of early diffuse systemic sclerosis (SSc) and how they differ from later disease.MethodsSkin biopsy RNA from 48 patients in the Prospective Registry for Early Systemic Sclerosis (PRESS) cohort (mean disease duration 1.3 years) and 33 matched healthy controls was examined by next-generation RNA sequencing. Data were analysed for cell type-specific signatures and compared with similarly obtained data from 55 previously biopsied patients in Genetics versus Environment in Scleroderma Outcomes Study cohort with longer disease duration (mean 7.4 years) and their matched controls. Correlations with histological features and clinical course were also evaluated.ResultsSSc patients in PRESS had a high prevalence of M2 (96%) and M1 (94%) macrophage and CD8 T cell (65%), CD4 T cell (60%) and B cell (69%) signatures. Immunohistochemical staining of immune cell markers correlated with the gene expression-based immune cell signatures. The prevalence of immune cell signatures in early diffuse SSc patients was higher than in patients with longer disease duration. In the multivariable model, adaptive immune cell signatures were significantly associated with shorter disease duration, while fibroblast and macrophage cell type signatures were associated with higher modified Rodnan Skin Score (mRSS). Immune cell signatures also correlated with skin thickness progression rate prior to biopsy, but did not predict subsequent mRSS progression.ConclusionsSkin in early diffuse SSc has prominent innate and adaptive immune cell signatures. As a prominently affected end organ, these signatures reflect the preceding rate of disease progression. These findings could have implications in understanding SSc pathogenesis and clinical trial design.

Synopsis Systemic sclerosis (SSc) is a heterogeneous disease of unknown etiology and with limited effective therapies. It is characterized by autoimmunity, vasculopathy and fibrosis and is clinically manifested by multi-organ involvement. Interstitial lung disease (ILD) is a common complication of the disease and is associated with significant morbidity and mortality. The diagnosis of ILD hinges upon careful clinical evaluation as well as pulmonary function tests (PFTs) and high resolution computed tomography (HRCT). A number of pro-inflammatory and pro-fibrotic mediators are involved in the pathogenesis of SSc-ILD, with transforming growth factor-beta (TGF-β) playing a key role in the development of fibrosis. Despite recent advances in the understanding of the mechanisms of disease initiation and progression, effective therapeutic options are still limited. A number of experimental therapies are currently in early phase clinical trials and show promise.

Objective We previously implicated the lipid mediator lysophosphatidic acid (LPA) in dermal fibrosis in systemic sclerosis (SSc). Here we identify the role of the LPA-producing enzyme autotaxin (ATX), and connect the ATX-LPA and IL-6 pathways in SSc. Methods We evaluated a novel ATX inhibitor, PAT-048, on fibrosis and IL-6 expression in the bleomycin (BLM) mouse model of dermal fibrosis. We utilized SSc patient and control dermal fibroblasts to evaluate LPA induction of IL-6, and IL-6 induction of ATX. We next evaluated whether LPA-induced ATX expression is dependent on IL-6, and whether baseline IL-6 expression in SSc fibroblasts is dependent on ATX. Finally, we compared ATX and IL-6 expression in SSc and healthy subject skin. Results PAT-048 markedly attenuated BLM-induced dermal fibrosis when initiated before or after fibrosis development. LPA stimulated human dermal fibroblast IL-6 expression, and IL-6 stimulated fibroblast ATX expression, connecting the ATX-LPA and IL-6 pathways in an amplification loop. IL-6 knockdown abrogated LPA-induced ATX expression in fibroblasts, and ATX inhibition attenuated IL-6 expression in fibroblasts and the skin of BLM-challenged mice. Both ATX and IL-6 expression were increased in SSc skin, and LPA-induced IL-6 levels and IL-6-induced ATX levels were increased in SSc fibroblasts compared to controls. Conclusion ATX is required for the development and maintenance of dermal fibrosis in the BLM model and enables two major mediators of SSc fibrogenesis, LPA and IL-6, to amplify each other’s production. Our results suggest that concurrent inhibition of these two pathways may be an effective therapeutic strategy for SSc fibrosis.