Peptidylarginine deiminases (PADs) have an important role in the pathogenesis of generating citrullinated proteins which is one type of protein posttranslation modifications (PTMs). Additionally, peptidylarginine deiminases 4 (PAD4) is a component of neutrophil extracellular traps (NET) that leads to autoimmune disease during NETosis. Our aim was to check the PAD4 enzyme expression at level of gene and protein expression in streptozotocin (STZ) induced diabetic rat pancreas and checking the link between PAD4 and inflammatory cytokines. Wistar rats were divided into two groups: control group and diabetic STZ group. STZ was administered by intraperitoneally (60 mg/kg/ body weight). Rats were caged for six weeks and then terminated. Pancreatic tissue was harvested for measurement of PAD4 protein expression, PAD4 mRNA, citrulli-nated histone-3 protein (CITH3), cytokines and Ca2+ content. All measurements in diabetic rats were significantly in-creased compared to non-diabetic rats (p

Rheumatoid arthritis (RA) is an autoimmune disease mainly characterized by joint inflammation. It presents extra-articular manifestations, with the lungs one of the affected areas. Among these, damage to the pulmonary interstitium (Interstitial Lung Disease -ILD) has been linked to proteins involved in the inflammatory process and related to extracellular matrix deposition and lung fibrosis establishment. Peptidyl arginine deiminase enzymes (PAD), which carry out protein citrullination, play a role in this context. A genetic association analysis was conducted on genes encoding two PAD isoforms, PAD2 and PAD4. This analysis also included ancestry informative markers and protein level determination in samples from patients with rheumatoid arthritis, RA-associated ILD, and clinically healthy controls. Significant single nucleotide variations (SNV) and a haplotype were identified as susceptibility factors for ILD-RA development. Elevated levels of PAD4 were found in ILD-RA cases, while PADI2 showed an association with RA susceptibility. This document presents the data obtained from the conducted research, which has been published.

Excessive neutrophil influx and activation in lungs during infections, such as manifest during the ongoing SARS CoV-2 pandemic, have brought neutrophil extracellular traps (NETs) and the con-comitant release of granule contents that damage surrounding tissues into sharp focus. Neutro-phil proteases, which are known to participate in NET release, also enable the binding of the viral spike protein to cellular receptors and assist in the spread of infection. Blood and tissue fluids normally also contain liver-derived protease inhibitors that balance the activity of proteases. In-terestingly, neutrophils themselves also express the protease inhibitor alpha-1-antitrypsin (AAT), the product of the SERPINA-1 gene, and store it in neutrophil cytoplasmic granules. The absence of AAT or mutations in the SERPINA-1 gene promote lung remodeling and fibrosis in diseases such as chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS) and increase the risk of allergic responses. Recent observations point to the fact that re-duced activity of AAT presents a major susceptibility factor for severe COVID-19. Here, we focus attention on the mechanism of neutrophil elastase (NE) in NET release and its inhibition by AAT as an additional factor that may determine the severity of COVID-19