Systemic sclerosis following COVID-19 infection with recurrent corticosteroid-induced scleroderma renal crisis

Molecular mimicry in the pathogenesis of autoimmune rheumatic diseases

Autoimmune rheumatic diseases (ARDs) are a heterogeneous group of conditions characterized by excessive and misdirected immune responses against the body's own musculoskeletal tissues. Their exact aetiology remains unclear, with genetic, demographic, behavioural and environmental factors implicated in disease onset. One prominent hypothesis for the initial breach of immune tolerance (leading to autoimmunity) is molecular mimicry, which describes structural or sequence similarities between human and microbial proteins (mimotopes). This similarity can lead to cross-reactive antibodies and T-cell receptors, resulting in an immune response against autoantigens. Both commensal microbes in the human microbiome and pathogens can trigger molecular mimicry, thereby potentially contributing to the onset of ARDs. In this review, we focus on the role of molecular mimicry in the onset of rheumatoid arthritis and systemic lupus erythematosus. Moreover, implications of molecular mimicry are also briefly discussed for ankylosing spondylitis, systemic sclerosis and myositis.

Systemic sclerosis (positive anti-Ro 52 and anti-centromere antibodies) in a patient after COVID-19 infection: a rare case report

Introduction and importance

The SARS-CoV-2 is the source of COVID-19, a respiratory disease. It typically manifests as restricted pulmonary symptoms, but autoimmune dysfunction might occasionally show up. A COVID-19 infection may cause a multi-system connective tissue disease known as systemic sclerosis (SSc). In patients who recovered from COVID-19, autoimmunity may have multiple underlying causes.

Case presentation

The authors report the case of a 68-year-old female who, 1 month after contracting COVID-19, complained of dyspnoea and muscle exhaustion. The patient was treated for post-COVID syndrome. She developed symptoms of chronic dyspnoea, pale fingers, pursed lips, trouble chewing and swallowing, and muscle weakness after 7 weeks. A chest high-resolution computerised tomography (HRCT) scan suggested interstitial lung disease. Clinical characteristics and an autoantibody profile containing anti-Ro 52 and anti-centromere antibodies pointed towards SSc. She was treated with azathioprine and prednisolone at a reduced dosage, and she is now stable with monthly follow-ups.

Clinical discussion

COVID-19 might induce cytokine storms and immunological dysregulation, ultimately culminating in autoimmune manifestations. Several autoantibodies are observed in autoimmune illnesses in post-COVID-19 infection patients. Our situation is distinct because SSc following a COVID-19 infection is not commonly seen as an autoimmune illness.

Conclusion

The number of patients with rare autoimmune diseases, like SSc, following COVID-19 has been rising. Therefore, we should consider the possibility of autoimmune disease when looking into a patient who presents strangely or has developed new symptoms after COVID and should contact the patient's management immediately.

SARS-CoV-2 spike protein accelerates systemic sclerosis by increasing inflammatory cytokines, Th17 cells, and fibrosis

BACKGROUND

Coronavirus disease 2019 (COVID-19) induces a dysfunctional immune response, inflammation, autoantibody production, and coagulopathy, which are symptoms that bear resemblance to those of autoimmune diseases, including systemic sclerosis (SSc).

METHODS

While there is a single case report suggesting an association between COVID-19 and SSc, the effects of COVID-19 on SSc are not yet fully understood. Human embryonic kidney 293 (HEK293) cells were transfected with the SARS-CoV-2 spike protein gene, in the presence of TGF-β. The expression levels of fibrosis-related proteins were measured via Western blotting. A bleomycin (BLM)-induced SSc mouse model was employed, wherein mice were injected with the gene encoding the SARS-CoV-2 spike protein and the ACE2 receptor. The levels of fibrosis, autoantibodies, thrombotic factors, and inflammatory cytokines in tissues and serum were analyzed.

RESULTS

In vitro, the expression levels of fibrosis marker proteins were elevated in the spike protein group compared to the control group. In vivo, the skin thickness of SSc mice increased following exposure to the SARS-CoV-2 spike protein. Furthermore, the levels of autoantibodies and thrombotic factors, such as anti-phospholipid antibodies (APLA), were significantly increased in the presence of the protein. Flow cytometry analysis revealed increased expression of the proinflammatory cytokine IL-17 in the skin, lungs, and blood. Moreover, tissue fibrosis and levels of inflammatory cytokines in skin and lung tissues were markedly escalated in SSc mice subjected to the protein.

CONCLUSION

COVID-19 may accelerate the development and progression of SSc by intensifying fibrosis through the upregulation of inflammation, autoantibody production, and thrombosis.