Objectives
Tissue fibrosis in SSc is driven by active fibroblasts (myofibroblasts). Previous studies have shown the intracellular chloride channel 4 (CLIC4) mediates the activation of cancer-associated fibroblasts. In this study we investigated the role of CLIC4 in SSc fibroblast activation.
Methods
Fibroblasts were obtained from full thickness skin biopsies from SSc patients (early-diffuse). RNA and protein were collected from the fibroblasts and CLIC4 transcript and protein levels were assessed by qPCR and western blot. SSc patient fibroblasts were treated with the chloride channel inhibitors nitro-2-(3-phenylpropylamino)benzoic acid and indyanyloxyacetic acid 94.
Results
CLIC4 was expressed at significantly higher levels in SSc patients’ fibroblasts compared with healthy controls, at both the transcript (3.7-fold) and protein (1.7-fold) levels. Inhibition of the TGF-β receptor and its downstream transcription factor SMAD3 led to a reduction in CLIC4 expression, confirming this pathway as the main driver of CLIC4 expression. Importantly, treatment of SSc fibroblasts with known pharmacological inhibitors of CLIC4 led to reduced expression of the myofibroblast markers collagen type 1 and α-smooth muscle actin, inferring a direct role for CLIC4 in disease pathogenesis.
Conclusions
We have identified a novel role for CLIC4 in SSc myofibroblast activation, which strengthens the similarities of SSc fibroblasts with cancer-associated fibroblasts and highlights this channel as a novel target for therapeutic intervention.
ObjectivesTo assess antibody and T cell responses to SARS-CoV-2 vaccination in patients with rheumatoid arthritis (RA) on disease-modifying antirheumatic drugs (DMARDs).MethodsThis prospective study recruited 100 patients with RA on a variety of DMARDs for antibody and T cell analysis, pre-vaccination and 4 weeks post-vaccination. Positive antibody response was defined as sera IgG binding to ≥1 antigen. Those that remained seronegative after first vaccination were retested 4 weeks after second vaccination; and if still seronegative after vaccination three. A T cell response was defined an ELISpot count of ≥7 interferon (IFN)γ-positive cells when exposed to spike antigens. Type I IFN activity was determined using the luminex multiplex assay IFN score.ResultsAfter vaccine one, in patients without prior SARS-CoV-2 exposure, 37/83 (45%) developed vaccine-specific antibody responses, 44/83 (53%) vaccine-specific T cell responses and 64/83 (77%) developed either antibody or T cell responses. Reduced seroconversion was seen with abatacept, rituximab (RTX) and those on concomitant methotrexate (MTX) compared to 100% for healthy controls (p<0.001). Better seroconversion occurred with anti-tumour necrosis factor (TNF) versus RTX (p=0.012) and with age ≤50 (p=0.012). Pre-vaccine SARS-CoV-2 exposure was associated with higher quantitative seroconversion (≥3 antibodies) (p<0.001). In the subgroup of non-seroconverters, a second vaccination produced seroconversion in 54% (19/35), and after a third in 20% (2/10). IFN score analysis showed no change post-vaccine.ConclusionPatients with RA on DMARDs have reduced vaccine responses, particularly on certain DMARDs, with improvement on subsequent vaccinations but with approximately 10% still seronegative after three doses.
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