Peripheral Inflammatory and Immune Landscape in Multiple System Atrophy: A Cross‐Sectional Study

ABSTRACT Background Neuroinflammation might contribute to the pathogenesis of multiple systemic atrophy (MSA). However, specific alterations in the peripheral inflammatory and immune profiles of patients with MSA remain unclear. Objectives To determine the peripheral inflammatory and immune profiles of patients with MSA and their potential value as biomarkers for facilitating clinical diagnosis and monitoring disease severity. Methods This cross‐sectional study included 235, 240, and 235 patients with MSA, patients with Parkinson's disease (PD), and healthy controls (HCs), respectively. Inflammatory and immune parameters were measured in peripheral blood, differences between groups were assessed, and clusters were analyzed. Associations between the parameters and clinical characteristics of MSA were assessed using Spearman and partial correlation analyses. Results Significant differences were observed especially in monocytes, neutrophils‐to‐lymphocyte ratio (NLR) and neutrophils‐to‐lymphocyte ratio (MPV) between MSA patients and HCs ( P < 0.01). Monocytes and uric acid (UA) levels were also significantly different between the MSA and PD patients ( P < 0.05). The combination of NLR and MPV distinguished MSA‐P patients from HCs (areas under the curve = 0.824). In addition, complement components C4 and C3 were significantly correlated with the Scale Outcomes in PD for Autonomic Symptoms and Wexner scale, whereas immunoglobulin G (IgG) was significantly correlated with scores of Unified Multiple System Atrophy Rating Scale ( P < 0.05). Conclusions In MSA patients, monocytes, NLR and MPV might serve as potential diagnostic biomarkers, whereas MLR, C3, C4, and IgG significantly correlate with disease severity. © 2023 International Parkinson and Movement Disorder Society.