Effects of B Cell Depletion by CD19-Targeted Chimeric Antigen Receptor T Cells in a Murine Model of Systemic Sclerosis

OBJECTIVE

Our goal was to study the tolerance and efficacy of two B cell depletion strategies, including one with CD19-targeted chimeric antigen receptor (CAR) T cells, in a preclinical model mimicking the severe lung damages observed in systemic sclerosis.

METHODS

B cell depletion strategies were evaluated in the Fra-2 transgenic (Tg) mouse model. We considered a first group of 16 untreated mice, a second group of 15 mice receiving a single dose of anti-CD20 monoclonal antibody (mAb), and a third group of 8 mice receiving CD19-targeted CAR-T cells in combination with anti-CD20 monoclonal antibody. After six weeks of clinical evaluation, different validated markers of inflammation, lung fibrosis, and pulmonary vascular remodeling were assessed.

RESULTS

CD19-targeted CAR-T cells infusion in combination with anti-CD20 mAb resulted in a deeper B cell depletion than anti-CD20 mAb alone in the peripheral blood and lesional lungs of Fra-2 Tg mice. CAR-T cell infusion worsened the clinical score and increased mortality in Fra-2 Tg mice. In line with the above findings, CAR-T cell infusion significantly increased lung collagen content, the histological fibrosis score, and right ventricular systolic pressure. CAR-T cells accumulated in lesional lungs and promoted T activation and inflammatory cytokine production. Treatment with anti-CD20 mAb in monotherapy had no impact on lung inflammation-driven fibrosis and pulmonary hypertension.

CONCLUSION

B cell therapies failed to show efficacy in the Fra2 Tg mice. The exacerbated Fra-2 lung inflammatory burden stimulated accumulation and expansion of activated CD19-targeted CAR-T cells, secondarily inducing T cell activation and systemic inflammation, finally leading to disease worsening.

Arsenic trioxide demonstrates efficacy in a mouse model of preclinical systemic sclerosis

BACKGROUND

Uncontrolled T-cell activation plays a key role in systemic sclerosis (SSc). Arsenic trioxide (ATO) has immunological effects and has demonstrated potential in preclinical SSc models. In this study, we assessed the efficacy of ATO in Fra2 transgenic (Fra2TG) mice, which develop severe vascular remodeling of pulmonary arterioles and nonspecific interstitial pneumonia-like lung disease, closely resembling human SSc-associated pulmonary hypertension, therefore partially resembling to the SSc human disease.

METHODS

The efficacy of ATO in Fra2TG mice was evaluated through histological scoring and determination of cell infiltration. Fibrotic changes in the lungs were assessed by measuring collagen content biochemically, using second harmonic generation to measure fibrillar collagen, and imaging via computed tomography. Cardiovascular effects were determined by measuring right ventricular systolic pressure and vessel remodeling. The mechanism of action of ATO was then investigated by analyzing lung cell infiltrates using flow cytometry and bulk RNA with sequencing techniques.

RESULTS

After ATO treatment, the Ashcroft histological score was substantially decreased by 33% in ATO-treated mice compared to control mice. Other investigations of fibrotic markers showed a trend of reduction in various measurements of fibrosis, but the differences did not reach significance. Further cardiovascular investigations revealed convergent findings supporting a beneficial effect of ATO, with reduced right ventricular systolic pressure and medial wall thickness, and a significant decrease in the number of muscularized distal pulmonary arteries in ATO-treated Fra2TG mice compared to untreated Fra2TG mice. Additionally, inflammatory cell infiltration was also markedly reduced in lesioned lungs. A reduction in the frequency of CD4 + and T effector memory cells, and an increase in the percentage of CD4 + T naive cells in the lungs of ATO-treated Fra-2TG mice, was observed when compared to PBS group Fra-2Tg mice. RNA-seq analysis of ATO-treated mouse lungs revealed a downregulation of biological pathways associated with immune activity and inflammation, such as T-cell activation, regulation of leucocyte activation, leucocyte cell-cell adhesion, and regulation of lymphocyte activation.

CONCLUSIONS

Our results suggest the clinical relevance of ATO treatment in SSc. Using the Fra2TG mouse model, we observed significant lung histological changes, a trend towards a decrease in various fibrotic makers, and a strong reduction in vascular remodeling. The mechanism of action of ATO appears to involve a marked counteraction of the immune activation characteristic of SSc, particularly T-cell involvement. These findings pave the way for further studies in SSc.

Relevance of circulating Semaphorin 4A for rheumatoid arthritis response to treatment

The lack of validated tools to predict rheumatoid arthritis (RA) disease course warrants the development of new reliable biomarkers. Our aim was to evaluate the merit of circulating SEMA4A for the prediction of outcomes in patients with RA. In a first cohort of 101 consecutive RA patients followed up for 41 ± 15 months, increased baseline SEMA4A levels were identified as an independent predictor of treatment failure (hazard ratio, HR 2.71, 95% CI 1.14-6.43), defined by the occurrence of patient-reported flares and initiation or change of targeted therapy. The highest predictive value of treatment failure was obtained with the combination of increased circulating SEMA4A and/or Disease Activity Score (DAS) 28-CRP > 3.2 and/or active synovitis on doppler ultrasound (HR 10.42, 95% CI 1.41-76.94). In a second independent cohort of 40 consecutive RA patients who initiated new therapy because of insufficient disease control, baseline SEMA4A levels were significantly higher in patients who further experienced none or moderate response, and SEMA4A concentrations were markedly decreased in the group of patients with good clinical response as compared to non-responders. Circulating SEMA4A appears as an appealing biomarker in RA with ability to predict treatment failure, and with association with response to therapy.

POS0538 PREDICTING VALUE OF CIRCULATING SEMAPHORIN 4A FOR RHEUMATOID ARTHRITIS PROGRESSION

Background

The lack of validated tools to predict rheumatoid arthritis (RA) disease course warrants the development of new reliable biomarkers. We have previously detected increased SEMA4A expression in endothelial cells, synovial tissue, and serum of patients with RA. In addition, SEMA4A serum levels correlated with multiple clinical, biological, and power doppler ultrasound markers of disease activity and angiogenesis (1).

Objectives

To evaluate the merit of circulating semaphorin 4A (SEMA4A) for the prediction of disease progression in RA patients.

Methods

Prospective monocentric observational study including consecutive RA patients between May 2016 and February 2018 with available SEMA4A concentrations, measured by quantitative ELISAs (Coud-Clone Corp, Katy, TX). Increased SEMA4A concentrations were defined as values >94 ng/mL, as previously reported (1). Patients were followed up on an annual basis until August 2021. Primary endpoints were the occurrence of patient-reported flares with swollen joints and the necessity to initiate or change a targeted biologic or synthetic disease-modifying anti-rheumatic drugs.

Results

A total of 101 patients (85 females, 84%) were included, with a mean age of 58±13 years and a mean disease duration of 14±11 years. During a follow-up period of 41±15 months, disease flares occurred in 38 patients and targeted therapy was added or modified in 26 patients because of insufficient disease control. Increased baseline SEMA4A levels were predictive of flares and treatment escalation (hazard ratio, HR: 2.43, 95% confidence interval, CI 1.27-4.68 and 2.73, 95%CI 1.24-5.96, respectively) (Figure 1A-B). Multivariate Cox analyses confirmed that SEMA4A was an independent predictors of flares and treatment escalation (HR: 2.12, 95%CI 1.04-4.32 and 2.71, 95%CI1.14-6.43, respectively), and revealed that DAS28-CRP and synovial hyperhemia were independent predictors of flares. Baseline age, disease duration, ACPA or RF positivity, smoking status, presence of erosions, line of targeted DMARDs, treatment with corticosteroids and CRP levels were not predictive of these outcomes. SEMA4A remained predictive of flares and treatment escalation in the 58 patients with a DAS28 <3.2 at baseline (HR: 3.68, 95%CI 1.33-10.17 and 3.50, 95%CI 1.02-12.01, respectively). Baseline SEMA4A levels also identified more active and difficult to treat patients who maintained higher mean DAS28-CRP values during the follow-up period (Figure 1C). The highest predictive value of flares and treatment escalation was obtained with the combination of increased circulating SEMA4A and/or DAS28-CRP>3.2 and/or the presence of synovial hyperemia on power-doppler ultrasound (HR:4.88, 95%CI 1.50-15.89 and 10.42, 95%CI 1.41-76.94, respectively).

Figure 1.

A-C: Predictive value of SEMA4A for the progression of rheumatoid arthritis. A, Disease flare-free survival according to circulating SEMA4A concentrations (≤ or > 94 ng/mL). B, Time to treatment escalation according to circulating SEMA4A concentrations (≤ or > 94 ng/mL). C, Course of the DAS28-CRP during the follow-up period according to baseline SEMA4A concentrations (≤ or > 94 ng/mL). All data are shown as the mean ± SEM. * p<0.05, ** p<0.01 and *** p<0.001, determined by Student’s t test.

Conclusion

Circulating SEMA4A was a robust biomarker of disease progression in this cohort, complementary of the DAS28 and synovial hyperemia on power-doppler ultrasound. These results need to be confirmed in replication cohorts.

References

[1]Avouac et al, Arthritis Rheumatol 2021

Disclosure of Interests

None declared.

Driving Role of Interleukin-2-Related Regulatory CD4+ T Cell Deficiency in the Development of Lung Fibrosis and Vascular Remodeling in a Mouse Model of Systemic Sclerosis

OBJECTIVE

Systemic sclerosis (SSc) is a debilitating autoimmune disease characterized by severe lung outcomes resulting in reduced life expectancy. Fra-2-transgenic mice offer the opportunity to decipher the relationships between the immune system and lung fibrosis. This study was undertaken to investigate whether the Fra-2-transgenic mouse lung phenotype may result from an imbalance between the effector and regulatory arms in the CD4+ T cell compartment.

METHODS

We first used multicolor flow cytometry to extensively characterize homeostasis and the phenotype of peripheral CD4+ T cells from Fra-2-transgenic mice and control mice. We then tested different treatments for their effectiveness in restoring CD4+ Treg cell homeostasis, including adoptive transfer of Treg cells and treatment with low-dose interleukin-2 (IL-2).

RESULTS

Fra-2-transgenic mice demonstrated a marked decrease in the proportion and absolute number of peripheral Treg cells that preceded accumulation of activated, T helper cell type 2-polarized, CD4+ T cells. This defect in Treg cell homeostasis was derived from a combination of mechanisms including impaired generation of these cells in both the thymus and the periphery. The impaired ability of peripheral conventional CD4+ T cells to produce IL-2 may greatly contribute to Treg cell deficiency in Fra-2-transgenic mice. Notably, adoptive transfer of Treg cells, low-dose IL-2 therapy, or combination therapy changed the phenotype of Fra-2-transgenic mice, resulting in a significant reduction in pulmonary parenchymal fibrosis and vascular remodeling in the lungs.

CONCLUSION

Immunotherapies for restoring Treg cell homeostasis could be relevant in SSc. An intervention based on low-dose IL-2 injections, as is already proposed in other autoimmune diseases, could be the most suitable treatment modality for restoring Treg cell homeostasis for future research.

Acazicolcept (ALPN-101), a dual ICOS/CD28 antagonist, demonstrates efficacy in systemic sclerosis preclinical mouse models

Background

Uncontrolled immune response with T cell activation has a key role in the pathogenesis of systemic sclerosis (SSc), a disorder that is characterized by generalized fibrosis affecting particularly the lungs and skin. Costimulatory molecules are key players during immune activation, and recent evidence supports a role of CD28 and ICOS in the development of fibrosis. We herein investigated the efficacy of acazicolcept (ALPN-101), a dual ICOS/CD28 antagonist, in two complementary SSc-related mouse models recapitulating skin fibrosis, interstitial lung disease, and pulmonary hypertension.

Methods

Expression of circulating soluble ICOS and skin-expressed ICOS was investigated in SSc patients. Thereafter, acazicolcept was evaluated in the hypochlorous acid (HOCL)-induced dermal fibrosis mouse model and in the Fra-2 transgenic (Tg) mouse model. In each model, mice received 400 μg of acazicolcept or a molar-matched dose of an Fc control protein twice a week for 6 weeks. After 6 weeks, skin and lung were evaluated.

Results

ICOS was significantly increased in the sera from SSc patients and in SSc skin biopsies as compared to samples from healthy controls. Similar body weight changes were observed between Fc control and acazicolcept groups in both HOCL and Fra-2 Tg mice suggesting a good tolerance of acazicolcept treatment. In mice challenged with HOCL, acazicolcept induced a significant decrease in dermal thickness, collagen content, myofibroblast number, and inflammatory infiltrates characterized by B cells, T cells, neutrophils, and macrophages. In the Fra-2 Tg mouse model, acazicolcept treatment reduced lung collagen content, fibrillar collagen, histological fibrosis score, and right ventricular systolic pressure (RVSP). A reduction in frequency of CD4+ and T effector memory cells and an increase in the percentage of CD4+ T naïve cells in spleen and lung of acazicolcept-treated Fra-2 Tg mice was observed as compared to Fc control-treated Fra-2 Tg mice. Moreover, acazicolcept reduced CD69 and PD-1 expression on CD4+ T cells from the spleen and the lung. Target engagement by acazicolcept was demonstrated by blockade of CD28 and ICOS detection by flow cytometry in treated mice.

Conclusions

Our results confirm the importance of costimulatory molecules in inflammatory-driven fibrosis. Our data highlight a key role of ICOS and CD28 in SSc. Using complementary models, we demonstrated that dual ICOS/CD28 blockade by acazicolcept decreased dermal and pulmonary fibrosis and alleviated pulmonary hypertension. These results pave the way for subsequent research on ICOS/CD28-targeted therapies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02709-2.

Erosive arthritis autoantibodies in systemic sclerosis

OBJECTIVE

We aimed to evaluate in two large SSc French cohorts the prevalence and associated factors with the autoantibodies linked to erosive arthritis.

METHODS

448 SSc patients were recruited from May 2015 to January 2019. Standardized clinical and laboratory variables were collected in accordance with the EUSTAR database. ELISAs for IgM rheumatoid factor (RF), IgG anti-citrullinated proteins (ACPA) and IgG anti-carbamylated proteins antibodies (anti-CarP) were all determined in a central laboratory. The prevalence and clinical associations of the different antibodies were investigated.

RESULTS

RF positivity was observed in 113 patients (25%) compared to 39 (9%) for ACPA and 63 (14%) for anti-CarP antibodies. Through multivariate regression analysis, both RF and ACPA positivity resulted to be associated with RA overlap disease (OR 5.7, 95% CI 2.3-13.8 and OR 44.1, 95% CI 15.4-126.3, respectively). Additionally, ACPA was found to be significantly related to synovitis/ tenosynovitis (OR 1.7, 95% CI 1.0-2.6). RF positivity was associated to a "vascular subset" (i.e. any major vascular complication) (OR 2.1, 95% CI 1.3-3.4). Moreover, anti-CarP antibodies were associated with a fibrotic subset and with digital ulcers (OR 2.0, 95% CI 1.1-3.6 and OR 1.9, 95% CI 1.1-3.4).

CONCLUSION

We corroborated that ACPA could be useful in identifying patients with a more prominent joint disease and RA overlap disease. Of the most interest we found that anti-CarP antibodies could be a relevant biomarker related to fibrotic skin and lung disease.

POS0378 CCN1: AN ANGIOGENIC ACTOR IMPLICATED IN THE STRUCTURAL DAMAGES OF RHEUMATOID ARTHRITIS

Background:

We have previously shown that decreased expression of the deacetylase sirtuin-1 (SIRT1) contributes to the proliferative, activated and proangiogenic profile of endothelial cells (EC) in rheumatoid arthritis (RA) (1). The matricellular protein CCN1, characterized by proangiogenic and immunomodulatory properties, may be directly implicated in these processes, since its expression is negatively regulated by SIRT1 (1).

Objectives:

To study the implication of CCN1 in RA pathogenesis.

Methods:

CCN1 expression was assessed in ECs (25 RA and 10 controls) by quantitative RT-PCR, western blot and ELISA, in the synovial tissue (5 RA and 5 controls) by immunohistochemistry and immunofluorescence, and in the serum (205 RA and 20 controls) by ELISA. Invalidation of CCN1 in RA ECs was achieved through the use of shRNA and neutralizing monoclonal antibodies. The functional consequences of CCN1 invalidation in RA ECs were studied i) in vitro by the analysis of proliferation (cell impedance), tube formation in Matrigel and migration in Boyden chambers; and ii) in vivo in the murine model of tumor neoangiogenesis.

Results:

CCN1 mRNA and protein expression were increased by 1.72- (p = 0.012) and 7.2-fold (p=0.008) in RA ECs compared to controls, respectively. CCN1 concentrations were significantly increased in RA EC culture supernatants (930±153 vs. 359±199 pg/mL, p=0.007). CCN1 was overexpressed in the synovial tissue of RA patients (Figure 1A) and confocal microscopy analyses revealed a prominent CCN1 expression in the vascular endothelium (CD31 +) and T cells (CD3 +) (Figure 1B).

In vitro, recombinant TNF-α and IL-17 induced the mRNA and protein expression of CCN1 in RA ECs. CCN1 invalidation was associated with reduced proliferative capacities, delayed capillary tube formation and decreased migration of RA ECs (Figure 1E). In vivo, subcutaneous transplantation of CT26 tumor cells combined with RA ECs transfected with CCN1 shRNA to CB17 SCID mice was associated with a 51% reduction in tumor volume (p=0.008) and a 27% reduction in tumoral vascular density (p=0.032) compared with mice transplanted with MOCK transfected RA-ECs (Figure 1F).

Serum concentrations of CCN1 were significantly reduced in the serum of RA patients compared to controls (233±118 vs. 279±75 pg/mL, p=0.045) (Figure 1C). However, serum CCN1 concentrations were significantly higher in the presence of bone erosions (253±139 vs. 202±7 pg/mL, p=0.002) (Figure 1D) and correlated with radiographic Larsen score (r=0.3, p=0.001) and HAQ (r=0.25, p=0.012).

Conclusion:

CCN1 is overexpressed in ECs and the synovial tissue of patients with RA. CCN1 also regulate the functional properties of RA ECs and their angiogenic potential in vivo. CCN1 could represent a new therapeutic target, which is being evaluated in experimental models of erosive arthritis.

CCN1 may be a reliable biomarker of structural damages given the association between its serum concentrations and the extent of radiographic lesions. The performance of CCN1 serum levels to predict structural progression is under investigation.

References:

[1]Leblond et a, Ann Rheum Dis 2020.

Figure 1.

Implication of CCN1 in the pathogenesis of rheumatoid arthritis (RA). A, Representative immunohistochemistry staining for CCN1. B, Representative confocal microscopy analyses. C-D, CCN1 serum concentrations; statistical test: Student t test, ** p<0.01. E, Representative images of RA endothelial cell (EC) migration; Y-axis shows the number of migrated cells, statistical test: Wilcoxon test, * p<0.05. F, Representative subcutaneous tumors, Y-axis shows the fluorescence area in %, statistical test: Wilcoxon test, * p<0.05.

Disclosure of Interests:

None declared

Implication of the deacetylase sirtuin-1 on synovial angiogenesis and persistence of experimental arthritis

OBJECTIVES

To decipher the phenotype of endothelial cells (ECs) derived from circulating progenitors issued from patients with rheumatoid arthritis (RA).

METHODS

RA and control ECs were compared according to their proliferative capacities, apoptotic profile, response to tumour necrosis factor (TNF)-α stimulation and angiogenic properties. Microarray experiments were performed to identify gene candidates relevant to pathological angiogenesis. Identified candidates were detected by RT-PCR and western blot analysis in ECs and by immunohistochemistry in the synovium. Their functional relevance was then evaluated in vitro after gene invalidation by small interfering RNA and adenoviral gene overexpression, and in vivo in the mouse model of methyl-bovine serum albumin-(mBSA)-induced arthritis.

RESULTS

RA ECs displayed higher proliferation rate, greater sensitisation to TNF-α and enhanced in vitro and in vivo angiogenic capacities. Microarray analyses identified the NAD-dependent protein deacetylase sirtuin-1 (SIRT1) as a relevant gene candidate. Decreased SIRT1 expression was detected in RA ECs and synovial vessels. Deficient endothelial SIRT1 expression promoted a proliferative, proapoptotic and activated state of ECs through the acetylation of p53 and p65, and lead the development of proangiogenic capacities through the upregulation of the matricellular protein cysteine-rich angiogenic protein-61. Conditional deletion of SIRT1 in ECs delayed the resolution of experimental methyl-bovine serum albumin-(mBSA)-induced arthritis. Conversely, SIRT1 activation reversed the pathological phenotype of RA ECs and alleviates signs of experimental mBSA-induced arthritis.

CONCLUSIONS

These results support a role of SIRT1 in RA and may have therapeutic implications, since targeting angiogenesis, and especially SIRT1, might be used as a complementary therapeutic approach in RA.

Estrogens Counteract the Profibrotic Effects of TGF-β and their Inhibition Exacerbates Experimental Dermal Fibrosis

Systemic sclerosis primarily affects women. This sex bias raises the question on the role female hormones could play in the development of fibrosis, which is largely unknown. Our aim was to evaluate the effects of estrogens in the development of experimental dermal fibrosis, in the mouse models of bleomycin-induced dermal fibrosis and tight skin (Tsk-1) mice, and on the activation of dermal fibroblasts by transforming growth factor-β (TGF-β). Estrogen inhibition, obtained through gene inactivation for the estrogen receptor-αknockout or treatment with tamoxifen, exacerbated skin fibrosis in the bleomycin model and in the Tsk-1 mice. In the dermal fibroblasts, treatment with 17-β-estradiol significantly decreased the stimulatory effects of TGF-β on collagen synthesis and myofibroblast differentiation, decreased the activation of canonical TGF-β signaling, and markedly reduced the expression of the TGF-β target genes. Tamoxifen reversed the inhibitory effects of estrogens by restoring Smad2/3 phosphorylation and TGF-β-induced collagen synthesis. Our results demonstrate a beneficial effect of estrogens in dermal fibrosis. Estrogens reduce the TGF-β-dependent activation of dermal fibroblasts, and estrogen inhibition leads to a more severe experimental dermal fibrosis. These findings are consistent with the prominent development of systemic sclerosis in postmenopausal women and the greater severity of the disease in men.

T-cell costimulation blockade is effective in experimental digestive and lung tissue fibrosis

Background

We aimed to investigate the efficacy of abatacept in preclinical mouse models of digestive involvement, pulmonary fibrosis, and related pulmonary hypertension (PH), mimicking internal organ involvement in systemic sclerosis (SSc).

Methods

Abatacept has been evaluated in the chronic graft-versus-host disease (cGvHD) mouse model (abatacept 1 mg/mL for 6 weeks), characterized by liver and intestinal fibrosis and in the Fra-2 mouse model (1 mg/mL or 10 mg/mL for 4 weeks), characterized by interstitial lung disease (ILD) and pulmonary vascular remodeling leading to PH.

Results

In the cGvHD model, abatacept significantly decreased liver transaminase levels and markedly improved colon inflammation. In the Fra-2 model, abatacept alleviated ILD, with a significant reduction in lung density on chest microcomputed tomography (CT), fibrosis histological score, and lung biochemical markers. Moreover, abatacept reversed PH in Fra-2 mice by improving vessel remodeling and related cardiac hemodynamic impairment. Abatacept significantly reduced fibrogenic marker levels, T-cell proliferation, and M1/M2 macrophage infiltration in lesional lungs of Fra-2 mice.

Conclusion

Abatacept improves digestive involvement, prevents lung fibrosis, and attenuates PH. These findings suggest that abatacept might be an appealing therapeutic approach beyond skin fibrosis for organ involvement in SSc.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1694-9) contains supplementary material, which is available to authorized users.

The Nrf2-Antioxidant Response Element Signaling Pathway Controls Fibrosis and Autoimmunity in Scleroderma

Systemic sclerosis (SSc) is an autoimmune disease with fibrosis of the skin and internal organs and vascular alterations. Dysregulations in the oxidant/antioxidant balance are known to be a major factor in the pathogenesis of the disease. Indeed, reactive oxygen species (ROS) trigger neoepitopes leading to a breach of immune tolerance and autoimmune responses, activate fibroblasts to proliferate and to produce excess of type I collagen. ROS also alter endothelial cells leading to vascular dysfunction. Glutathione (GSH) is the most potent antioxidant system in eukaryotic cells. Numerous studies have reported a defect in GSH in SSc animal models and humans, but the origin of this defect remains unknown. The transcription factor NRF2 is a key player in the antioxidant defense, as it can induce the transcription of antioxidant and cytoprotective genes, including GSH, through its interaction with the antioxidant response elements. In this work, we investigated whether NRF2 could be implicated in the pathogenesis of SSc, and if this pathway could represent a new therapeutic target in this orphan disease with no curative medicine. Skin biopsies from 11 patients and 10 controls were harvested, and skin fibroblasts were extracted. Experimental SSc was induced both in BALB/c and in nrf2^-/- mice by daily intradermal injections of hypochloric acid. In addition, diseased BALB/c mice were treated with an nrf2 agonist, dimethyl fumarate, or placebo. A drop in nrf2 and target genes mRNA levels was observed in skin fibroblasts of SSc patients compared to controls. Moreover, the nrf2 pathway is also downregulated in skins and lungs of SSc mice. In addition, we observed that nrf2^-/- mice have a more severe form of SSc with increased fibrosis and inflammation compared to wild-type SSc mice. Diseased mice treated with the nrf2 agonist dimethyl fumarate (DMF) exhibited reduced fibrosis and immune activation compared to untreated mice. The ex vivo treatment of skin fibroblasts from SSc mice with DMF restores GSH intracellular content, decreases ROS production and cell proliferation. These results suggest that the nrf2 pathway is highly dysregulated in human and SSc mice with deleterious consequences on fibrosis and inflammation and that Nrf2 modulation represents a therapeutic target in SSc.

Pan-PPAR agonist IVA337 is effective in experimental lung fibrosis and pulmonary hypertension

Objective

To evaluate the antifibrotic effects of the pan-peroxisome proliferator-activated receptor (PPAR) agonist IVA337 in preclinical mouse models of pulmonary fibrosis and related pulmonary hypertension (PH).

Methods

IVA337 has been evaluated in the mouse model of bleomycin-induced pulmonary fibrosis and in Fra-2 transgenic mice, this latter being characterised by non-specific interstitial pneumonia and severe vascular remodelling of pulmonary arteries leading to PH. Mice received two doses of IVA337 (30 mg/kg or 100 mg/kg) or vehicle administered by daily oral gavage up to 4 weeks.

Results

IVA337 demonstrated at a dose of 100 mg/kg a marked protection from the development of lung fibrosis in both mouse models compared with mice receiving 30 mg/kg of IVA337 or vehicle. Histological score was markedly reduced by 61% in the bleomycin model and by 50% in Fra-2 transgenic mice, and total lung hydroxyproline concentrations decreased by 28% and 48%, respectively, as compared with vehicle-treated mice. IVA337 at 100 mg/kg also significantly decreased levels of fibrogenic markers in lesional lungs of both mouse models. In addition, IVA337 substantially alleviated PH in Fra-2 transgenic mice by improving haemodynamic measurements and vascular remodelling. In primary human lung fibroblasts, IVA337 inhibited in a dose-dependent manner fibroblast to myofibroblasts transition induced by TGF-β and fibroblast proliferation mediated by PDGF.

Conclusion

We demonstrate that treatment with 100 mg/kg IVA337 prevents lung fibrosis in two complementary animal models and substantially attenuates PH in the Fra-2 mouse model. These findings confirm that the pan-PPAR agonist IVA337 is an appealing therapeutic candidate for these cardiopulmonary involvements.

Transethnic meta-analysis identifies GSDMA and PRDM1 as susceptibility genes to systemic sclerosis

OBJECTIVES

Systemic sclerosis (SSc) is an autoimmune disease characterised by skin and systemic fibrosis culminating in organ damage. Previous genetic studies including genome-wide association studies (GWAS) have identified 12 susceptibility loci satisfying genome-wide significance. Transethnic meta-analyses have successfully expanded the list of susceptibility genes and deepened biological insights for other autoimmune diseases.

METHODS

We performed transethnic meta-analysis of GWAS in the Japanese and European populations, followed by a two-staged replication study comprising a total of 4436 cases and 14 751 controls. Associations between significant single nuclear polymorphisms (SNPs) and neighbouring genes were evaluated. Enrichment analysis of H3K4Me3, a representative histone mark for active promoter was conducted with an expanded list of SSc susceptibility genes.

RESULTS

We identified two significant SNP in two loci, GSDMA and PRDM1, both of which are related to immune functions and associated with other autoimmune diseases (p=1.4×10^-10 and 6.6×10^-10, respectively). GSDMA also showed a significant association with limited cutaneous SSc. We also replicated the associations of previously reported loci including a non-GWAS locus, TNFAIP3. PRDM1 encodes BLIMP1, a transcription factor regulating T-cell proliferation and plasma cell differentiation. The top SNP in GSDMA was a missense variant and correlated with gene expression of neighbouring genes, and this could explain the association in this locus. We found different human leukocyte antigen (HLA) association patterns between the two populations. Enrichment analysis suggested the importance of CD4-naïve primary T cell.

CONCLUSIONS

GSDMA and PRDM1 are associated with SSc. These findings provide enhanced insight into the genetic and biological basis of SSc.

A candidate gene study identifies a haplotype of CD2 as novel susceptibility factor for systemic sclerosis

OBJECTIVES

Systemic sclerosis (SSc) is a rare autoimmune disease (AID) with a complex genetic etiology. Evidence for a shared pathogenesis across AIDs is given by the well-known pleiotropism of autoimmune genes. Recently, several unbiased approaches have identified an association between polymorphisms of the CD2 gene, and rheumatoid arthritis (RA) susceptibility. The objective of this study was to investigate whether CD2 polymorphisms are associated with SSc.

METHODS

Two SNPs of CD2, rs624988 and rs798036, were genotyped in a total of 1,786 SSc patients and 2,360 healthy individuals from two European populations (France and Italy). Meta-analyses were performed to assess whether an association exists between CD2 polymorphisms or haplotypes and SSc or its main subtypes.

RESULTS

The combined analyses revealed an association between the rs624988 A allele and SSc susceptibility: padj=0.023, OR=1.14 (95%CI 1.04-1.25). Single marker analysis did not reveal any association between rs798036 and SSc. Haplotype analysis identified that the A-T haplotype, previously described in RA, was associated with higher susceptibility for SSc (padj=0.029, OR=1.14, 95%CI 1.04-1.25) and with the positive anti-centromere antibody sub-group of SSc patients (padj=0.009, OR=1.19 95%CI 1.07-1.32). Genotype-mRNA expression correlations revealed that the CD2 risk haplotype was associated with decreased CD2 mRNA expression in SSc patients.

CONCLUSIONS

Our study establishes CD2 as a new susceptibility factor for SSc, in a European Caucasian population, confirming the sharing of autoimmune risk factors by SSc and RA.

Treatment with abatacept prevents experimental dermal fibrosis and induces regression of established inflammation-driven fibrosis

OBJECTIVE

Activated T cells are the main component of the inflammatory skin infiltrates that characterise systemic sclerosis (SSc). Our aim was to investigate the efficacy of abatacept, which tempers T-cell activation, in reducing skin fibrosis in complementary mouse models of SSc.

METHODS

The antifibrotic properties of abatacept were evaluated in the mouse models of bleomycin-induced dermal fibrosis and sclerodermatous chronic graft-versus-host disease, reflecting early and inflammatory stages of SSc. Thereafter, we studied the efficacy of abatacept in tight skin (Tsk-1) mice, an inflammation-independent mouse model of skin fibrosis.

RESULTS

Abatacept efficiently prevented bleomycin-induced skin fibrosis and was also effective in the treatment of established fibrosis. In this model, abatacept decreased total and activated T-cell, B-cell and monocyte infiltration in the lesional skin. Abatacept did not protect CB17-SCID mice from the development of bleomycin-induced dermal fibrosis, which supports that T cells are necessary to drive the antifibrotic effects of abatacept. Upon bleomycin injections, skin interleukin (IL) 6 and IL-10 levels were significantly reduced upon abatacept treatment. Moreover, treatment with abatacept ameliorated fibrosis in the chronic graft-versus-host disease model, but demonstrated no efficacy in Tsk-1 mice. The tolerance of abatacept was excellent in the three mouse models.

CONCLUSIONS

Using complementary models, we demonstrate that inhibition of T-cell activation by abatacept can prevent and induce the regression of inflammation-driven dermal fibrosis. Translation to human disease is now required, and targeting early and inflammatory stages of SSc sounds the most appropriate for positioning abatacept in SSc.