Human leukocyte antigen-DR15, low infant sibling exposure and multiple sclerosis: gene-environment interaction

Area of Science:

• Immunology
• Epidemiology
• Genetics

Background:

• Multiple sclerosis (MS) risk is associated with specific genetic factors like human leukocyte antigen-DRB1*1501-DQB1*0602 (HLA-DR15) genotype.
• Environmental factors, including infant sibling exposure and Epstein-Barr virus (EBV) infection, are also implicated in MS development.
• The interplay between genetic predisposition and early-life environmental exposures in MS pathogenesis remains incompletely understood.

Purpose of the Study:

• To investigate the interaction between HLA-DR15 positivity and infant sibling exposure on the risk of developing multiple sclerosis.
• To determine if this interaction is independent of Epstein-Barr nuclear antigen IgG levels.

Main Methods:

• A population-based case-control study was conducted in Tasmania, Australia.
• Data on HLA-DR15 genotype, infant sibling exposure, and Epstein-Barr nuclear antigen IgG levels were collected.
• Statistical analyses, including tests for interaction, were used to evaluate the combined effects of risk factors.

Main Results:

• A significant interaction was found between HLA-DR15 positivity and low infant sibling exposure, increasing multiple sclerosis risk by 7.88-fold (95% CI, 3.43-18.11).
• The combined effect was 3.9-fold greater than expected, indicating a synergistic relationship (p = 0.019).
• This interaction persisted regardless of Epstein-Barr nuclear antigen IgG levels.

Conclusions:

• Early life immune modulation, potentially involving HLA class II molecules, plays a crucial role in multiple sclerosis development.
• The findings highlight the importance of considering gene-environment interactions in understanding MS etiology.
• Further research into early life immune exposures and their influence on HLA-mediated immune responses is warranted.