Patterns of C1-Inhibitor Plasma Levels and Kinin-Kallikrein System Activation in Relation to COVID-19 Severity.

Background: Although more than four years have passed since the pandemic began, SARS-CoV-2 continues to be of concern. Therefore, research into the underlying mechanisms that contribute to the development of the disease, especially in more severe forms, remains a priority. Sustained activation of the complement (CS), contact (CAS), and fibrinolytic and kinin-kallikrein systems (KKS) has been shown to play a central role in the pathogenesis of the disease.

Rare connective tissue diseases in patients with C1-inhibitor deficiency hereditary angioedema: first evidence on prevalence and distribution from a large Italian cohort study.

Introduction: In patients with Hereditary Angioedema (HAE) related to primary C1 inhibitor deficiency (C1INH), the defective clearance of immune complexes and apoptotic materials along with impairment of normal humoral response potentially leads to autoimmunity. Few studies report evidence on autoimmune diseases in C1INH-HAE, but no large population studies focus on rare connective tissue diseases (RCTDs). We aim at evaluating for the first time prevalence and distribution of RCTDs - Systemic Lupus Erytematosus (SLE), primary Sjogren Syndrome (SjS), primary antiphospholipid syndrome (APS), Systemic Sclerosis (SSc), and mixed connective tissue diseases (MCTD) in a large Italian cohort of C1INH-HAE patients.