Inflammatory hallmarks in 6-OHDA- and LPS-induced Parkinson's disease in rats

Parkinson's disease (PD) is the second most common neurodegenerative disease, affecting more than 1% of aged people. PD, which was previously identified as movement disorder, now is recognized as a multi-factorial systemic disease with important pathogenetic and pathophysiological role of inflammation. Reproducing local and systemic inflammation, which is inherent in PD, in animal models is essential for maximizing the translation of their potential to the clinic, as well as for developing putative anti-inflammatory neuroprotective agents. This study was aimed to compare activation patterns of microglia/macrophage population and systemic inflammation indices in rats with 6-Hydroxydopamine (6-OHDA)- and Lipopolysaccharide (LPS)-induced PD. Metabolic and phenotypic characteristics of microglia/macrophage population were examined by flow cytometry, systemic inflammatory markers were calculated using hematological parameters in 6-OHDA- and LPS-lesioned Wistar rats 29 days after the surgery. Microglia/macrophages from rats in both models exhibited pro-inflammatory metabolic shift. Nevertheless, in LPS-lesioned animals, highly increased proportion of CD80/86+ cells in microglia/macrophage population was registered alongside increased values of systemic inflammatory indices: neutrophil to lymphocyte ratio (NLR), derived neutrophil to lymphocyte ratio (dNLR), platelet to lymphocyte ratio and systemic immune inflammation index (SII). There was significant positive correlation between the count of CD80/86+ cells and systemic inflammatory indices in these animals. Microglia/macrophages from 6-OHDA-lesioned rats were characterized by the increased fraction of CD206+ cells alongside decreased proportion of CD80/86+ cells. No signs of systemic inflammation were observed. Negative correlation between quantitation characteristics of CD80/86+ cells and values of systemic inflammatory indices was registered. Collectively, our data show that LPS-PD model unlike 6-OHDA-PD replicates crosstalk between local and systemic inflammatory responses, which is inherent in PD pathogenesis and pathophysiology.