The functional consequence of histone citrullination may vary, and, while citrullinated histones were less cytotoxic to endothelial cells, neutrophils, and bacteria, and proposed as curtailing immune reactions [33,34,35], hypercitrullinated autoantigens could drive the pathology in autoimmune diseases, and inhibition of citrullination by PAD4 inhibitors was protective against parenchymal organ damage [8,10,36]. This evidence concerns the gene PADI4 and autoimmune disease.