Decoding the multifaceted cellular and transcriptomic variations of natural killer cells generated from patients with Parkinson's disease.

Parkinson's disease (PD) is an intractable progressive neurodegenerative disease with poor prognosis in elder patients, which is largely attribute to the deficiency of ultimate pathogenesis. Longitudinal studies have indicated a pivotal role of natural killer (NK) cells, yet the systematic and detailed information of circulating NK cells in PD is largely unknowable. To explore the role of NK cells in PD, we isolated mononuclear cells from peripheral blood (PBMCs) by Ficoll-based density gradient centrifugation, and detected the content of total resident NK cells in healthy donors (HD-NKs) and PD patients (PD-NKs) and the concomitant subsets by flow cytometry (FCM) assay. Then, we took advantage of our well-established "3ILs"-based strategy for ex vivo NK cell expansion and activation, and followed by cellular viability and cytotoxicity assessment. By conducting RNA-sequencing (RNA-SEQ) and multifaceted bioinformatics analyses, we compared the transcriptomic signatures of expanded HD-NKs and PD-NKs. Compared to HD-NKs, PD-NKs showed increase in resident NK cells but minimal differences in expanded NK cells, together with diversity in the subpopulations of NK cells (CD16+, NKG2D+, NKp46+). Interestingly, PD-NKs revealed a moderate higher percentage of apoptotic cells and cytotoxicity upon the co-cultured Nalm6 and U937 tumor cell lines. Despite with high conservations in gene expression pattern and genetic variations, PD-NKs revealed multifaceted diversity in gene set-associated immune response and metabolism. Overall, our data revealed the multidimensional biological and transcriptomic signatures of resident and expanded NK cells generated from peripheral blood of PD patients and HDs. Our findings would provide new references for the further development of NK cell-based biomarkers for PD diagnosis and novel immunotherapy for neurodegenerative diseases.