Prevalence of anti-Ro52-kDa/SSA (TRIM21) antibodies and associated clinical phenotype in systemic sclerosis: Data from a French cohort, a systematic review and meta-analysis.

OBJECTIVES: Estimate the global prevalence of anti-Ro52-kDa/SSA (TRIM21) autoantibodies in systemic sclerosis (SSc), and describe the associated clinical phenotype, through a systematic review and meta-analysis of published reports and new data from our French cohort. METHODS: Anti-TRIM21 seropositivity and associated SSc characteristics were assessed in a cross-sectional study including 300 patients of Lille University Hospital. A systematic review of the literature was performed in Pubmed and Embase, followed by a meta-analysis, using data on prevalence, clinical/demographical/biological characteristics of SSc patients and the type of assay used for anti-TRIM21 antibodies detection (PROSPERO n° CRD42021223719). FINDINGS: In the cross-sectional study, anti-TRIM21 antibodies prevalence was 26% [95%CI: 21; 31]. Anti-centromere antibodies were the most frequent SSc specific autoantibodies coexisting with anti-TRIM21. Patients with anti-TRIM21 antibodies were more frequently women (91% vs 77%, p = 0.006), more likely to present an associated Sjögren's syndrome (19% vs 7%, p < 0.001), had a higher rate of pulmonary arterial hypertension (PAH) (15% vs 6%, p = 0.017) and a greater frequency of digestive complications such as dysphagia (12% vs 5%, p = 0.038) or nausea/vomiting (10% vs 3%, p = 0.009) than anti-TRIM21 negative patients. Thirty-five articles corresponding to a total of 11,751 SSc patients were included in the meta-analysis. In this population, the overall seroprevalence of anti-TRIM21 antibodies was 23% [95%CI: 21; 27] with a high degree of heterogeneity (I2: 93% Phet: <0.0001), partly explained by the methods of detection. Anti-TRIM21 seropositivity was positively associated with female sex (OR: 1.60 [95%CI: 1.25, 2.06]), limited cutaneous subset (OR: 1.29 [1.04, 1.61]), joint manifestations (OR: 1.33 [1.05, 1.68]), pulmonary hypertension (PH) (OR: 1.82 [1.42, 2.33]), and interstitial lung disease (ILD) (OR: 1.31 [1.07, 1.60]). INTERPRETATION: Anti-TRIM21 antibodies frequently co-exist with usual SSc antibodies, but are independently associated to a higher risk of cardio-pulmonary complications. The presence of these autoantibodies should therefore be considered when assessing the risk of developing PH and ILD, and deserves further studies on appropriate screening and follow-up of patients.

Can Antinuclear Antibodies Have a Pathogenic Role in Systemic Sclerosis?

Systemic sclerosis (SSc) is a connective tissue disease characterized by extensive fibrosis of the skin and internal organs, associated with vasculopathy and autoimmune features. Antinuclear antibodies (ANA) are found in almost all SSc patients and constitute strong diagnosis and prognosis biomarkers. However, it remains unclear whether ANA are simple bystanders or if they can have a role in the pathophysiology of the disease. One might think that the nuclear nature of their targets prevents any accessibility to autoantibodies. Nevertheless, recent data suggest that ANA could be pathogenic or at least contribute to the perennation of the disease. We review here first the indirect clues of the contribution of ANA to SSc: they are associated to the disease subtypes, they may precede disease onset, their titer correlates with disease activity and severity, there is an association between molecular subsets, and some patients can respond to B-cell targeting therapy. Then, we describe in a second part the mechanisms of ANA production in SSc from individual genetic background to post-transcriptional modifications of neoantigens. Finally, we elaborate on the potential mechanisms of pathogenicity: ANA could be pathogenic through immune-complex-mediated mechanisms; other processes potentially involve molecular mimicry and ANA penetration into the target cell, with a focus on anti-topoisomerase-I antibodies, which are the most probable candidate to play a role in the pathophysiology of SSc. Finally, we outline some technical and conceptual ways to improve our understanding in this field.

Effects of Immunoglobulins G From Systemic Sclerosis Patients in Normal Dermal Fibroblasts: A Multi-Omics Study.

Autoantibodies (Aabs) are frequent in systemic sclerosis (SSc). Although recognized as potent biomarkers, their pathogenic role is debated. This study explored the effect of purified immunoglobulin G (IgG) from SSc patients on protein and mRNA expression of dermal fibroblasts (FBs) using an innovative multi-omics approach. Dermal FBs were cultured in the presence of sera or purified IgG from patients with diffuse cutaneous SSc (dcSSc), limited cutaneous SSc or healthy controls (HCs). The FB proteome and transcriptome were explored using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and microarray assays, respectively. Proteomic analysis identified 3,310 proteins. SSc sera and purified IgG induced singular protein profile patterns. These FB proteome changes depended on the Aab serotype, with a singular effect observed with purified IgG from anti-topoisomerase-I autoantibody (ATA) positive patients compared to HC or other SSc serotypes. IgG from ATA positive SSc patients induced enrichment in proteins involved in focal adhesion, cadherin binding, cytosolic part, or lytic vacuole. Multi-omics analysis was performed in two ways: first by restricting the analysis of the transcriptomic data to differentially expressed proteins; and secondly, by performing a global statistical analysis integrating proteomics and transcriptomics. Transcriptomic analysis distinguished 764 differentially expressed genes and revealed that IgG from dcSSc can induce extracellular matrix (ECM) remodeling changes in gene expression profiles in FB. Global statistical analysis integrating proteomics and transcriptomics confirmed that IgG from SSc can induce ECM remodeling and activate FB profiles. This effect depended on the serotype of the patient, suggesting that SSc Aab might play a pathogenic role in some SSc subsets.

Initial characteristics and follow-up of patients with a diagnosis of angiotensin-converting enzyme inhibitor induced angioedema.

Background: A differential diagnosis between angiotensin-converting enzyme inhibitor (ACEi) angioedema (AE) and histaminergic AE (hAE) might be challenging. Follow-up data may help discriminate these conditions but are scarcely reported. Objective: To report on the follow-up of patients with suspected ACEi-AE and to describe the baseline characteristics of AE attacks in patients with a diagnosis of ACEi-AE after follow-up. Methods: Sixty-four patients with suspected ACEi-AE (i.e., with exposure to ACEi before the first attack, no urticaria associated, and normal C1-inhibitor levels) and at least one follow-up visit were included. Data were retrospectively collected at baseline and during the follow-up. Results: After the follow-up, the diagnosis of ACEi-AE was probable in only 30 patients. The remaining patients were reclassified as having probable hAE (21 patients) or undetermined-mechanism AE (13 patients). Patients with ACEi-AE were mostly men (61%), with a median age of 64 years (interquartile range [IQR] ±17 years), with a highly variable delay from ACEi introduction (median: 23 months; interquartile range: 103 months). Attacks preferentially involved lips (50%), tongue (47%), and throat (30%). Interestingly, patients with probable ACEi-AE after a follow-up also frequently presented with a history of allergy and atopic conditions (20%), attacks with preferential evening onset (25%), and spontaneous resolution in < 24 hours (26%), which are usually considered as suggestive of hAE. ACEi-AE attacks responded to icatibant in 79% of the patients. Conclusion: Patients with probable ACEi-AE were mostly men with facial involvement. A third of the patients with an initial suspected diagnosis of ACEi-AE had a final diagnosis of probable hAE. Although a follow-up of all patients should be a standard of care, it is critical to the correct diagnosis in the case of suspected bradykinin-associated AE, which may actually be due to histamine.

Passages in culture and stimulation conditions influence protein expression of primary fibroblasts.

Fibroblasts (Fb) are key effector cells in systemic sclerosis (SSc). Fb stimulation with transforming growth factor beta 1 (TGF-ß1) is considered as a positive control in studies assessing fibrogenesis. The lack of standardization of TGF-ß1 stimulation might be responsible for discrepancies in experiments performed in different conditions. Using quantitative proteomics analysis, we evaluated the impact of changes in experimental conditions on proteomic profiles of primary Fb. Principal component analysis (PCA) identified several groups of differentially expressed proteins influenced by cell passage, culture medium, and both concentration and duration of exposure to TGF-ß1 stimulation. Bioinformatics analysis revealed that late passages expressed proteins involved in senescence. TGF-ß1 concentration and time of stimulation were correlated with the expression of proteins involved in the fibrogenesis and inflammatory processes. These data underline the need for standardization of culture conditions to allow inter-data comparisons in future in vitro studies, especially when using "omics" approaches.