Polymorphisms of the immune-modulating receptor dectin-1 in pigs: their functional influence and distribution in pig populations

Dectin-1, a C-type lectin receptor that recognizes fungal beta-glucans, is involved in antifungal immunity and the regulation of intestinal immune homeostasis. Dectin-1 is involved in both synthesis and maturation of interleukin-1 beta, a key pro-inflammatory cytokine in immunity. Here, we assessed the genetic diversity in the gene encoding dectin-1 (CLEC7A) within various pig populations and examined the influence of these polymorphisms on the two different signaling pathways after ligand recognition. An amino-acid polymorphism located in the carbohydrate-recognition domain, leucine to serine at position 138 (L138S), which occurred exclusively in Japanese wild boars at low frequency, significantly increased NF-kappa B induction but not caspase-8 activity after stimulation with zymosan. In contrast, other amino-acid polymorphisms present at comparatively high frequency in commercial pig populations had little influence on ligand recognition. These results suggest that functionally neutral polymorphisms in dectin-1 are widespread in pig populations.