OBJECTIVE: 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).
RESULTS: 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]).
CONCLUSIONS: 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.

In a number of autoimmune diseases, for example, rheumatoid arthritis and systemic lupus erythematosus, it is known that autoantibodies are present before the clinical onset. Recently we have shown that autoantibodies can be found many years before symptom onset in primary Sjögren\'s syndrome. This implies that screening for autoantibodies may be used to identify individuals at risk of developing systemic autoimmune disease. Possibly, autoantibody screening may also contribute to detection of incipient malignancy. This concept stems from a novel finding, on scleroderma patients, suggesting that an anti-tumor immune response elicited by a mutated self-antigen will cross-react with the unmodified version of the self-antigen, and thus come to trigger the formation of autoantibodies.