Investigation of the influence of cyclin-dependent kinase inhibitors on neutrophils activation

Abstract

Neutrophils, the most abundant leukocytes, play a crucial role in the initial defense against invading microbes by detecting them through various receptor systems. Nevertheless, pathological activation of neutrophils is involved in many chronic and autoimmune diseases, such as epidermolysis bullosa acquisita (EBA) where activation of neutrophils ultimately elicits skin blisters. Current treatment primarily relies on immunosuppression, contributing to increased morbidity and mortality. Hence effective and safe therapeutic strategies are urgently needed. Cyclin-dependent kinase inhibitors (CDKIs) block endogenously cell cycle progression under unfavorable conditions, leading to apoptosis, prompting interest in their potential for treating autoinflammatory and autoimmune diseases, including EBA. This study explores the impact of eleven specific CDKIs on neutrophil activation induced by immune complexes (ICs) in vitro, utilizing assays for reactive oxygen species (ROS) release and fluorescence-activated cell sorting (FACS). Among the CDKIs tested, four CDKIs Palbociclib (PD-0332991) HCl (CDK4/6I), THZ2 (CDK7I), BAY 1251152 (CDK9I, PTEFbI), and OTS964 (TOPKI, CDK11I) significantly reduce ROS production in stimulated human polymorphonuclear leukocytes (PMNs). Two CDKIs Palbociclib (PD-0332991) HCl (CDK4/6I) and THZ2 (CDK7I) showed significance regarding reducing CD18pos cells, although no CDKI demonstrated significant effects on the reduction of CD62Lneg cells. All eleven inhibitors maintained a proportion of viable cells close to 100% compared to the IC- stimulated positive control. To summarize, CDKIs have emerged as promising candidates for anti-inflammatory therapeutics, owing to their capacity to modulate the resolution of inflammatory processes, and this work confirms this impression in vitro for EBA. Furthermore, of the 11 CDKIs analyzed, THZ2 (CDK7I) and OTS964 (TOPKI, CDK11I) stand out as the most promising for further testing of the efficacy of systemic application in the murine model of EBA induced by antibody transfer.