Dermatomyositis with Specific Autoantibodies Appearing after Sars-Cov-2 Infection or Mrna Vaccination: Hints at a Shared Pathogenetic Mechanism

ABSTRACT

Background. Environmental factors such as infections and vaccines are known to trigger dermatomyositis (DM), and during the recent SARS-CoV-2 pandemic this has become even clearer. SARS-CoV-2 infection may share features with anti-MDA5 DM, such as rapidly progressive lung involvement, cutaneous lesions and cytokine release syndrome. A few case reports of DM following SARSCoV-2 vaccination have been published, suggesting the onset of an aberrant immune response leading to DM with specific autoantibody signatures and severe organ impairment. Methods. Clinical and laboratory data of the 2 case reports were obtained from electronic clinical charts in Humanitas Research Hospital (Rozzano, Milan, Italy). Autoantibody analysis was performed by protein-immunoprecipitation for anti-MDA5 and immunoblot for anti-Ro52 and TIF1gamma antibodies as per protocol. Results. Case report 1 is a 71-year-old woman who developed fever, cough, and anosmia, which resolved spontaneously in two weeks, but did not undergo a nasopharyngeal swab, while her relatives were diagnosed with SARS-CoV-2 infection. When symptoms improved, she developed arthralgia and skin lesions on her face, chest, and hands for which she started topical treatment, with negative SARSCoV-2 nasopharyngeal swab and positive serum test for IgG against SARS-CoV-2 spike protein. For the persistence of the skin rash and arthralgia, she was admitted to our Department in March 2021. Blood tests showed mild elevation of C reactive protein (2.1 mg/L -normal value NV<5), aspartate (84 UI/L) and alanine aminotransferase (133 UI/L -NV<35), ferritin (595 ng/ml -NV<306), troponin I (19 ng/L -NV<14), and BNP (251 pg/ml -NV<100) with normal complete blood cell count, creatine kinase, C3 and C4. IgG antibodies for SARS-CoV-2 spike protein were confirmed to be elevated (96 AU/ml -NV<15). Autoantibodies associated with connective tissue diseases were tested and only anti-MDA5 antibodies were positive at immunoprecipitation. A punch biopsy of a Gottron-like lesion on the left hand showed leukocytoclastic vasculitis. We observed reduced capillary density with neoangiogenesis and ectasic capillaries at the nailfold capillaroscopy. EKG and ecocardiography were normal, while cardiac magnetic resonance detected abnormalities in the parametric sequences, consistent with signs of previous myocarditis. A lung CT scan revealed pulmonary emphysema while respiratory function tests demonstrated reduced volumes (FVC 82%, FEV1 64%, inadequate compliance CO diffusion test). Based on the biochemical and clinical findings, a diagnosis of anti-MDA5-associated DM with skin and heart involvement was made and treatment with low-dose methylprednisolone (0.25 mg/kg daily) and azathioprine 100 mg was started, then switched to mycophenolate because not effective on skin lesions. Case report 2 is an 84-year-old woman with history of colon cancer (surgical treatment) and oral lichen treated with low doses steroids in the last 2 years. After the 2nd dose of SARS-CoV-2 mRNA vaccination, in March 2021 she developed skin rash with V-sign, Gottron's papules, periungueal ulcers, muscle weakness and fatigue, thus she performed a rheumatologic evaluation. Blood tests showed mild elevation of creatine kinase (484 UI/L, NV <167), CK-MB (9.6ng/ml, NV <3.4), BNP (215 pg/ml -NV<100) with normal values of complete blood cell count, C3 and C4. Anti-Ro52kDa and TIF1gamma were positive at immunoblot, thus we confirmed a diagnosis of DM. The clinical evaluation also showed active scleroderma pattern at nailfold capillaroscopy, normal echocardiography, bronchiectasia but not interstitial lung disease at lung CT, and normal respiratory function tests (FVC 99%, FEV1 99%, DLCO 63%, DLCO/VA 81%). A PET-CT scan was performed to exclude paraneoplastic DM, and treatment with steroids and mycophenolate was started. Conclusions. SARS-CoV-2 may induce mechanisms for escaping the innate immunity surveillance and causing autoimmune diseases, but more clinical and functional studies are needed to demonstrate this possible association.