PADI4 and rheumatoid arthritis: Indeed, PAD4 inhibition using pan-PAD inhibitors like Cl-amidine or PAD4-specific inhibitors such as GSK199 can disrupt NETosis and hence ameliorate disease severity in mouse models of SLE, RA, and AAV.[31,32,33] Moreover, recent studies revealed that PAD4-specific inhibitors have the advantage of few off-target effects, further supporting their utility as treatment options for rheumatic patients.[43] However, the efficacy of PAD4 inhibitors in the treatment of rheumatic diseases remains to be determined in clinical trials.