Many of the potential immune therapeutic targets are similarly affected in adult-onset neurodegenerative diseases such as Alzheimer’s (AD) disease, Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), and frontotemporal dementia (FTD), but also in a seemingly distinct Niemann-Pick type C disease with primarily juvenile-onset. This strongly argues for an overlap in pathogenic mechanisms. The commonly researched immune targets include various immune cell subsets such as microglia, peripheral macrophages, or regulatory T cells (Tregs), the complement system, and other soluble factors. In this review, we will compare these neurodegenerative diseases from a clinical point of view and point out the common pathways and mechanisms of protein aggregation, neurodegeneration and/or neuroinflammation that could potentially lead to shared treatment strategies. We also describe the common therapeutic approaches in treating the immune dysfunctions in these disorders, moving from immunization to microbiome regulation and stem cell treatment.

Introduction: Parkinson’s disease (PD) is a prevalent neurodegenerative disorder, with several proposed pathogenic mechanisms. Given the established role of mitochondrial dysfunction in PD, this study seeks to investigate the enrichment of rare genetic variants tied to mitochondrial metabolism in cases of early-onset and familial PD. Methods: We performed a retrospective analysis on 248 early-onset and familial PD patients and 1622 control individuals. We assessed both pathway-level and gene-level burden of germline rare variants detected using exome sequencing in 467 nuclear genes related to mitochondrial metabolism. Results: Gene-set mutation burden analysis indicated an increased burden in genes associated with mtDNA maintenance. In addition, gene-level analysis identified a possible association between PD and rare variant burden in 14 mitochondrial metabolism-related genes under dominant or recessive inheritance models. Conclusions: Our findings support a potential contribution of rare germline variants affecting mitochondrial metabolism to the susceptibility in early-onset and familial PD.