Lactobacillus rhamnosus and Flavanol‐enriched Cocoa Powder Altered the Immune Response to Infection with the Parasitic Nematode Ascaris suum in a Pig Model

Abstract

Immunomodulatory effects of the probiotic bacteria Lactobacillus rhamnosus (LGG) and prebiotic effects of flavanol‐enriched cocoa have been previously reported. This study evaluated if feeding LGG and flavanol‐enriched cocoa powder to pigs would modulate the host response against a prototypical type 2 allergic immune response induced by infection with Ascaris suum. Three month old male pigs (n=8/diet) were fed diets containing 1 x 1010 cfu LGG/day or placebo (maltodextrin) and 0 or 26 grams of flavanol‐enriched cocoa powder (Acticoa, Barry‐Callebaut, Belgium)/day for 7 weeks in a 2 x2 design. Seventeen days before euthanasia, all pigs were inoculated with infective Ascaris suum eggs to mimic type 2 allergic immune response. LGG abundance in feces and intestinal contents, expression of immunomodulatory genes in the tracheobronchial lymph nodes (TBLNs), alveolar macrophages (AM), and mesenteric lymph nodes (MLNs) were determined by RT‐PCR. When compared to placebo‐treated pigs, the abundance of LGG was increased in the intestinal contents and feces of pigs fed LGG. Consumption of cocoa powder together with LGG did not affect LGG abundance. Ascaris suum induced interleukin‐13, eosinophil peroxidase, and chemokine ligand 26 gene expression levels were reduced in TBLNs of pigs fed LGG regardless of cocoa consumption. LGG consumption induced an increase in toll‐like receptor (TLR)‐9 and tumor necrosis factor (TNF)‐α gene expression in AM of infected pigs. In contrast, TLR2 gene expression in AM was only increased in response to feeding cocoa powder. After 24 hr ex vivo stimulation with LPS, AM from LGG and cocoa powder fed pigs had increased TNFα gene expression compared with other treatment groups suggesting a synergistic effect in response to the infection. Moreover, LGG fed pigs exhibited a significant increase of TLR2 and TLR4 in MLNs compared to placebo‐treated pigs. Overall, this study demonstrated that feeding LGG reduced Ascaris suum‐induced eosinophil activity in TBLNs and increased gene expression of TLRs and pro‐inflammatory TNF‐α, while consumption of cocoa powder alone modulated TLR2 expression in AM. The combination of feeding LGG and cocoa powder synergistically stimulated TNFα gene expression in LPS‐stimulated AM.Support or Funding InformationThis study was supported by USDA Project Number 8040‐51530‐056‐00 and Inter agency agreement 8040‐51530‐056‐13 with ODS at NIH