Objective: The present study aimed to determine whether a different peripheral immune profile and neutrophil-to-lymphocyte ratio were present in Parkinson’s disease (PD) patients compared with healthy controls.

Background: Inflammation plays a major role in the pathophysiology of PD. The neutrophil-to-lymphocyte ratio in peripheral blood has been proven to be a novel inflammatory marker. Studies on the neutrophil-to-lymphocyte ratio and PD have shown controversial results.

Method: We conducted a case-control study including 377 PD patients and 355 healthy controls. Leukocytes, subpopulations, and the neutrophil-to-lymphocyte ratio were measured in both groups. Multivariate linear regression analyses were applied to determine the differences between groups and the association between neutrophil-to-lymphocyte ratio and clinical characteristics in PD. Electronic databases were searched in October 2020 to perform a meta-analysis to clarify the association between neutrophil-to-lymphocyte ratio and PD.

Results: In our case-control study, PD patients showed significantly lower lymphocyte counts than healthy controls (1.83±0.59 x 10^3 cells/μL vs 2.14±0.66 x 10^3 cells/μL; p<0.001). The neutrophil-to-lymphocyte ratio was significantly higher in PD patients compared with healthy controls (2.47±1.1 vs 1.98±0.91, p<0.001). No association between neutrophil-to-lymphocyte ratio and age at onset, disease severity, motor complications or disease duration was found in PD group. The meta-analysis, including our study and 7 previously published case-control studies (1219 PD patients and 862 healthy controls), showed that the neutrophil-to-lymphocyte ratio was likely to be higher in PD patients than in healthy controls (standardized mean difference 0.27; 95% CI -0.05 to 0.6).

Conclusion: Our study indicated that PD patients had an altered peripheral immune profile and a higher neutrophil-to-lymphocyte ratio, regardless of age at onset, disease duration or motor disease severity. These alterations could reflect the role of chronic inflammation and immune dysregulation in the pathogenesis of PD and could help in the development of future diagnostic biomarkers and immunomodulatory therapies.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/peripheral-immune-profile-and-neutrophil-to-lymphocyte-ratio-in-parkinsons-disease/