Role of increased neutrophil extracellular trap formation on acute kidney injury in COVID-19 patients.

Background: A strong association between elevated neutrophil extracellular trap (NET) levels and poor clinical outcomes in patients with coronavirus infection 2019 (COVID-19) has been reported. However, while acute kidney injury (AKI) is a common complication of COVID-19, the role of NETs in COVID-19-associated AKI is unclear. We investigated the association between elevated NETs and AKI and the prognostic role of NETs in COVID-19 patients. Methods: Two representative markers of NETs, circulating nucleosomes and myeloperoxidase-DNA, were measured in 115 hospitalized patients. Serum levels of interleukin [IL]-6, monocyte chemotactic protein-1 [MCP-1], plasma von Willebrand factor (vWF) and urinary biomarkers of renal tubular damage (ß2-microglobulin [ß2M] and kidney injury molecule 1 [KIM-1]) were measured. Results: AKI was found in 43 patients (37.4%), and pre-existing chronic kidney disease (CKD) was a strong risk factor for AKI. Higher circulating NET levels were a significant predictor of increased risk of initial ICU admission, in-hospital mortality (adjusted HR 3.21, 95% CI 1.08-9.19) and AKI (OR 3.67, 95% CI 1.30-10.41), independent of age, diabetes, pre-existing CKD and IL-6 levels. There were strong correlations between circulating nucleosome levels and urinary KIM-1/creatinine (r=0.368, p=0.001) and ß2M (r=0.218, p=0.049) levels. NETs were also strongly closely associated with serum vWF (r = 0.356, p<0.001), but not with IL-6 or MCP-1 levels. Conclusions: Elevated NETs were closely associated with AKI, which was a strong predictor of mortality. The close association between NETs and vWF may suggest a role for NETs in COVID-19-associated vasculopathy leading to AKI.

IgA vasculitis presenting as nephrotic syndrome following COVID-19 vaccination: a case report.

BACKGROUND: Following the strong recommendation for coronavirus disease 2019 (COVID­19) vaccination, many patients with medical comorbidities are being immunized. However, the safety of vaccination in patients with autoimmune diseases has not been well established. We report a new case of biopsy-proven IgA vasculitis with nephritis presenting as a nephrotic syndrome after mRNA COVID-19 vaccination in a patient with a history of leukocytoclastic vasculitis. CASE PRESENTATION: A 76-year-old man with a history of cutaneous leukocytoclastic vasculitis presented with purpura in both lower limbs, followed by nephrotic syndrome after the second dose of BNT162b2 mRNA COVID-19 vaccination. Skin and renal biopsy revealed IgA vasculitis with nephritis. The patient's past medical history of leukocytoclastic vasculitis and features of chronicity in renal pathology suggest an acute exacerbation of preexisting IgA vasculitis after COVID-19 vaccination. After the steroid and renin-angiotensin system inhibitor use, purpura and acute kidney injury recovered within a month. Subnephrotic proteinuria with microscopic hematuria remained upon follow-up. CONCLUSION: Physicians should keep in mind the potential (re)activation of IgA vasculitis following mRNA COVID-19 vaccines. It is important to closely monitor COVID-19 vaccinated patients, particularly those with autoimmune diseases.