Tadashi Umehara¹ · Masahiro Mimori¹ · Tatsushi Kokubu² · Masakazu Ozawa³ · Tomotaka Shiraishi¹ · Takeo Sato¹ · Asako Onda¹ · Hiromasa Matsuno¹ · Shusaku Omoto² · Renpei Sengoku³ · Hidetomo Murakami^1,4 · Hisayoshi Oka¹ · Yasuyuki Iguchi¹

^{Received: 22 September 2023 / Revised: 17 March 2024 / Accepted: 18 March 2024
© Springer-Verlag GmbH Germany, part of Springer Nature 2024}

Abstract
Background Accumulating evidence suggests that peripheral inflammation is associated with the pathogenesis of Parkinson’s disease (PD). We examined peripheral immune profiles and their association with clinical characteristics in patients with DLB and compared these with values in patients with PD. Methods We analyzed peripheral blood from 93 participants (drug-naïve DLB, 31; drug-naïve PD, 31; controls, 31). Absolute leukocyte counts, absolute counts of leukocyte subpopulations, and peripheral blood inflammatory indices such as neutrophil-to-lymphocyte ratio were examined. Associations with clinical characteristics, cardiac sympathetic denervation, and striatal 123I-2-carbomethoxy-3-(4-iodophenyl)-N-(3-fluoropropyl) nortropane (123I-FP-CIT) binding were also examined. Results Patients with DLB had lower absolute lymphocyte and basophil counts than did age-matched controls (both; p < 0.005). Higher basophil counts were marginally associated with higher global cognition (p = 0.054) and were significantly associated with milder motor severity (p = 0.020) and higher striatal 123I-FP-CIT binding (p = 0.038). By contrast, higher basophil counts were associated with more advanced PD characterized by decreased global cognition and severe cardiac sympathetic denervation. Although lower lymphocyte counts had relevance to more advanced PD, they had little relevance
to clinical characteristics in patients with DLB. Higher peripheral blood inflammatory indices were associated with lower body mass index in both DLB and PD.
Conclusions As in patients with PD, the peripheral immune profile is altered in patients with DLB. Some peripheral immune cell counts and inflammatory indices reflect the degree of disease progression. These findings may deepen our knowledge on the role of peripheral inflammation in the pathogenesis of DLB.

Keywords Dementia with Lewy bodies · Parkinson’s disease · Peripheral immune cell · Peripheral blood inflammatory
indices · Lymphocyte counts · Basophil counts

GKB-NON-2024-00197