Case Report: ANCA-Associated Vasculitis Presenting With Rhabdomyolysis and Pauci-Immune Crescentic Glomerulonephritis After Pfizer-BioNTech COVID-19 mRNA Vaccination.

As the coronavirus disease 2019 (COVID-19) pandemic is ongoing and new variants of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) are emerging, there is an urgent need for COVID-19 vaccines to control disease outbreaks by herd immunity. Surveillance of rare safety issues related to these vaccines is progressing, since more granular data emerge with regard to adverse events of COVID-19 vaccines during post-marketing surveillance. Interestingly, four cases of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) presenting with pauci-immune crescentic glomerulonephritis (GN) after COVID-19 mRNA vaccination have already been reported. We here expand our current knowledge of this rare but important association and report a case of AAV presenting with massive rhabdomyolysis and pauci-immune crescentic GN after Pfizer-BioNTech COVID-19 mRNA vaccination. As huge vaccination programs are ongoing worldwide, post-marketing surveillance systems must continue to assess vaccine safety important for the detection of any events associated with COVID-19 vaccination. This is especially relevant in complex diseases where diagnosis is often challenging, as in our patient with AAV presenting with massive rhabdomyolysis and pauci-immune crescentic GN.

Complement Factor D as a Strategic Target for Regulating the Alternative Complement Pathway.

The complement system is central to first-line defense against invading pathogens. However, excessive complement activation and/or the loss of complement regulation contributes to the development of autoimmune diseases, systemic inflammation, and thrombosis. One of the three pathways of the complement system, the alternative complement pathway, plays a vital role in amplifying complement activation and pathway signaling. Complement factor D, a serine protease of this pathway that is required for the formation of C3 convertase, is the rate-limiting enzyme. In this review, we discuss the function of factor D within the alternative pathway and its implication in both healthy physiology and disease. Because the alternative pathway has a role in many diseases that are characterized by excessive or poorly mediated complement activation, this pathway is an enticing target for effective therapeutic intervention. Nonetheless, although the underlying disease mechanisms of many of these complement-driven diseases are quite well understood, some of the diseases have limited treatment options or no approved treatments at all. Therefore, in this review we explore factor D as a strategic target for advancing therapeutic control of pathological complement activation.

Pediatric P-ANCA vasculitis following COVID-19.

BACKGROUND: Perinuclear anti-neutrophil cytoplasmic antibodies (P-ANCA) are associated with a multisystem vasculitis affecting small blood vessels in the body. A handful of adult patients who developed vasculitis post-COVID-19 have been reported. Although SARS-CoV-2 has been shown to drive an exaggerated immune response in the pediatric population, such as in Multisystem Inflammatory Syndrome in Children (MIS-C), only one case of vasculitis following COVID-19 has been reported previously in children. CASE PRESENTATION: Seventeen-year-old male with a past medical history of COVID-19 pneumonia two months prior presented with acute kidney injury and diffuse alveolar hemorrhage. Rheumatologic workup revealed P-ANCA and Myeloperoxidase (MPO) positivity. Kidney biopsy showed necrotizing glomerulonephritis with limited immune complex deposition. Subsequently, he was treated with steroids and plasmapheresis, and ultimately started on cyclophosphamide. CONCLUSIONS: To our knowledge, this report presents the second reported pediatric case of P-ANCA/MPO vasculitis following COVID-19.

ANCA-associated vasculitis after COVID-19.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) are systemic autoimmune diseases that may lead to renal failure due to the infiltration of mononuclear cells and the destruction of small- and medium-sized blood vessels. It has been shown that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may trigger the presentation or exacerbation of autoimmune diseases. Crescentic glomerulonephritis (GN) has rarely been reported in patients with Coronavirus disease-2019 (COVID-19). We present rare two cases with AAV after a recent diagnosis of COVID-19. The first case was 26-year-old male patient, who was presented with acute kidney injury after COVID-19. Serum creatinine increased and active urine sediment was seen. Serological evaluation showed anti-myeloperoxidase antibody was at a level of 80.6 U/mL. Kidney biopsy showed necrotizing GN with cellular crescents. Methylprednisolone, cyclophosphamide and plasma exchange were administered. He was discharged with hemodialysis. Second case was a 36-year-old female who was hospitalized because of fever, cough and dyspnea. After she was diagnosed with COVID-19, she had total hearing loss, with cavitary lesions on bilateral lung parenchyma and an acute kidney injury. Serological evaluation showed an elevated anti-proteinase-3 with a level of 1:32. Kidney biopsy showed necrotizing GN with cellular crescents. Renal function improved after methylprednisolone and cyclophosphamide treatment. With a systematic review of the literature, we found four cases of new-onset AAV due to COVID-19. Herein, we discuss two cases and provide a literature review on cases of new-onset pauci-immune GN after COVID-19 infection.

Impaired HVJ-stimulated Interferon producing capacity in MPO-ANCA-associated vasculitis with rapidly progressive glomerulonephritis lead to susceptibility to infection.

ANCA-associated RPGN leads to renal failure through systemic vasculitis and diffuse crescentic glomerulonephritis. MPO-ANCA-RPGN patients are highly susceptible to infections. Our aim in this study was to uncover reasons why these patients were susceptible to infections. We analyzed various aspects of type I interferon system including HVJ-stimulated IFN-α producing capacity and plasmacytoid dendritic cell (pDC) number in whole blood in MPO-ANCA-RPGN patients. Compared with healthy subjects, MPO-ANCA-RPGN patients showed impaired HVJ-stimulated IFN-α producing capacity and lower pDC number with or without glucocorticoid treatment. Immuno-histological staining of MPO-ANCA-RPGN kidney samples revealed a few but apparent pDC in T cell infiltrating regions even in patients with low pDC number in their peripheral blood. Patients' low HVJ-stimulated IFN-α producing capacity and pDC numbers persisted even after patients underwent several years of treatment. Former infection was determined using patients' serum BPI, Lamp-2 and Calprotectin, since they are reflective of a history of infection. These markers were higher in MPO-ANCA-RPGN patients than in healthy subjects. These results indicate that impaired HVJ-stimulated IFN-α production as well as dysfunction of the IFN system might have resulted from a previous bout of infection and can be partially implicated in patients' long-term susceptibility and vulnerability to infection.