A Possible Role for HSV-1-Specific Humoral Response and PILRA rs1859788 Polymorphism in the Pathogenesis of Parkinson’s Disease

The etiology of Parkinson’s disease (PD), a progressive nervous system disorder that affects movement, is still unknown; both genetic and environmental factor are believed to be involved in onset of the disease and its development. Herpes simplex virus type 1 (HSV-1), in particular, is suspected to have a role in PD. Paired Immunoglobulin-like type 2 receptor alpha (PILRA) is an inhibitory receptor that down-regulates inflammation and is expressed on innate immune cells. The PILRA rs1859788 polymorphism is protective against Alzheimer’s disease, even in relation with HSV-1 antibody titers, but no data are available in PD. We analyzed HSV-1 antibody titers and PILRA rs1859788 in PD (n = 51) and age-and sex-matched healthy controls (HC; n = 73). Results showed that HSV-1, but not cytomegalovirus (CMV) or human herpes virus type 6 (HHV-6) antibody titers were significantly higher in PD compared to HC (p = 0.045). The rs1859788 polymorphism was not differentially distributed between PD and HC, but the minor allele A was more frequently carried by PD (68%) compared to HC (50%) (p = 0.06). Notably, the rs1859788 minor allele A was statically more frequent in male PD (65%) compared to male HC (37%) (p = 0.036). Finally, no relation was found between HSV-1 antibody titers and PILRA genotype. Results herein suggest an involvement of HSV-1 in PD and indicate a possible interaction between PILRA gene polymorphisms and this neuropathology.