Profiling gene expression in mesenteric lymph nodes in pigs with different levels of resistance to Ascaris suum

A single nucleotide polymorphism on chromosome 4 (SNP TXNIP) has been reported to be associated with roundworm (Ascaris suum) burden in pigs. The objective of the present study was to profile the immune response mounted by pigs with two SNP TXNIP genotypes following an A. suum infection. We selected pigs with genotypes AA (n=24) and AB (n=23) and trickle-infected them with A. suum from eight weeks of age until necropsy eight weeks later.

An uninfected control group (AA; n=5 and AB; n=5) was also included. At post mortem, we collected mesenteric lymph nodes and measured the expression of 28 selected genes. Recordings of worm burdens confirmed our previous results that pigs of the AA genotype were more resistant to infection than AB pigs.

By estimating the genotype difference in relative expression levels in infected and uninfected animals, we found that IL-13 levels tended to change with genotype (P=0.077); specifically, pigs of the AA genotype had increased IL-13 expression following A. suum infection but IL-13 expression was unchanged in AB pigs.

Furthermore, IL-13 expression tended to be associated with total worm burden in AB pigs (P=0.07). The expression of chemokine ligand 17 (CCL17) was up-regulated in AA pigs (P<0.05) but not in AB pigs following A. suum infection. Pigs of genotype AB had higher expression of the high-affinity IgG receptor (FCGR1A) than AA pigs in both infected and non-infected animals (P=1.85*10-11).

In conclusion, our results suggest the two genotypes differ in the magnitude of their Th2-type response following A. suum infection.