Kinetics of Mononuclear Cell Subpopulations in the Peripheral Blood of Patients with Giant Cell Arteritis During the Acute Phase of the Disease: The Role of Steroids.

Background/Aim: Giant cell arteritis (GCA) represents the most prevalent form of systemic vasculitis in the elderly, primarily affecting the temporal artery, the extracranial branches of carotid arteries, and the aorta. GCA is a highly heterogeneous disease in terms of clinical and histological findings, pathophysiology, and treatment selection strategies. The disease is highly responsive to glucocorticosteroids (GCs), but almost half of patients may relapse following GCs tapering. The main hypothesis of GCA pathogenesis includes altered immune responses and changes in the vascular microenvironment, leading to a dynamic interplay between innate and adaptive immunity. The aim of this study is to explore the effect of GCs on the phenotype of peripheral mononuclear cell subpopulations and on the major inflammatory molecules detected in the peripheral blood of patients during the acute phase of the disease. Methods: Patient PBMCs will be studied using Cytometry by time of flight (CyTOF). Following the CyTOF analysis, Luminex Assay will be performed on the same patient samples to identify the kinetics of the most prominent inflammatory mediators correlating with the subpopulations detected. Patient population consists of 8 patients with GCA, 6 with polymyalgia rheumatica, as disease control group and 5 healthy controls (sex and age matched) at 3 time points: disease diagnosis, 48 and 96 hours after treatment administration. Conclusion: The identification of potential alterations in cell subpopulations and the kinetics of inflammatory mediators are expected to lead to the production of new knowledge regarding the role of corticosteroids in the phase of acute inflammatory response.