CDK7, CDK9, or CDK11 Inhibition Reduces Neutrophil-Driven Inflammation and Tissue Damage in Experimental Autoimmune Models

BackgroundCyclin-dependent kinases (CDKs) are involved in basic cellular processes like regulation of cell-cycle progression and transcription. However, recent data also indicate a specific role in terminally differentiated neutrophils by promoting reactive oxygen species (ROS) release, degranulation, neutrophil extracellular trap formation, or apoptosis. Since these mechanisms are implicated in multiple autoimmune diseases, we aimed to delineate the role of CDKs in IC-mediated autoimmune diseases both in vitro and in vivo. MethodsWe analyzed CDK gene expression in unstimulated and immune complex (IC)-stimulated neutrophils. Subsequently, we investigated the effect of pharmacological CDK inhibition on IC-activated neutrophil functions. To analyze the inhibitors in a more translational approach, we proceeded with the systemic and topical application of the effective inhibitors in a murine antibody transfer-induced local epidermolysis bullosa acquisita (EBA) model. The most efficient inhibitor, MC180295, was validated in two other IC-mediated models of autoimmune disease: Serum-transfer arthritis (STA), which also, but not exclusively, depends on neutrophils and immune thrombocytopenia (ITP), which is considered less neutrophil-dependent. ResultsWe found 14 CDKs expressed in unstimulated cells, while the IC-stimulation showed an upregulation of CDK2 and CDK4 expression. Inhibitors selectively targeting CDK1, CDK2, CDK4/6, CDK7, CDK9, CDK11, and CDK12 showed effects on different neutrophil functions (surface activation marker expression, ROS release, adhesion, apoptosis) in vitro. In the predominantly neutrophil-driven EBA model, we observed a reduction of disease severity upon treatment with CDK7, CDK9, or CDK11 inhibitors. Inhibiting these CDKs with topical THZ2, MC180295, or OTS964, respectively, also improved the clinical phenotype. In line with our hypothesis, MC180295 impaired the development of STA, but not ITP. ConclusionsCDK7, CDK11, and especially CDK9 inhibition show therapeutic potential in IC-driven neutrophil-mediated diseases such as rheumatoid arthritis and EBA.