Peptide Derivatives of Human and Rabbit Cathelicidin Reduce Inflammatory Cytokines in Peripheral Blood Mononuclear Cells of Rheumatoid Arthritis Patients

Peptides, as therapeutic agents, can mimic the actions of molecules involved in inflammatory disorders. Antimicrobial peptides (AMPs), generated by the innate immune system in all organisms, exhibit a broad spectrum of biological functionalities, including immunomodulation. The purpose of this study was to evaluate the effect of two modified peptide derivatives based on rabbit and human cathelicidin (nrCap18 and nhCap18) on the level of pro-inflammatory and anti-inflammatory cytokines in PBMCs of rheumatoid arthritis patients and healthy individuals in vitro. At first, peripheral blood samples were taken from seven rheumatoid arthritis patients and seven healthy individuals, and their PBMCs were isolated and cultured. Next, the toxicity of peptides was evaluated on PBMCs of these individuals, and the potential for hemolysis of these peptides on human blood erythrocytes was also calculated. After PBMCs were treated by peptide, cytokine level changes were investigated in the supernatants. These peptides showed low toxicity on PBMCs and human red blood cells. Also, these peptides could modulate and regulate cytokines in both patient/healthy groups. It is hoped that the effects of these peptides on cytokines modulation and regulation can open a new window for introducing an anti-inflammatory peptide. However, animal studies and clinical trials are needed to prove this claim.