Intraepithelial lymphocytes in the pig intestine: T cell and innate lymphoid cell contributions to intestinal barrier immunity

Abstract

Intraepithelial lymphocytes (IELs) include T cells and innate lymphoid cells that are important mediators of intestinal immunity and barrier defense, yet most knowledge of IELs is derived from the study of humans and rodent models. Pigs are an important global food source and promising biomedical model, yet relatively little is known about IELs in the porcine intestine, especially during formative ages of intestinal development. Due to the biological significance of IELs, global importance of pig health, and potential of early life events to influence IELs, we collate current knowledge of porcine IEL functional and phenotypic maturation in the context of the developing intestinal tract and outline areas where further research is needed. Based on available findings, we formulate probable implications of IELs on intestinal and overall health outcomes and highlight key findings in relation to human IELs to emphasize potential applicability of pigs as a biomedical model for intestinal IEL research. Review of current literature suggests the study of porcine intestinal IELs as an exciting research frontier with dual application for betterment of animal and human health.

Acute and persistent effects of oral glutamine supplementation on growth, cellular proliferation, and tight junction protein transcript abundance in jejunal tissue of low and normal birthweight pre-weaning piglets

“…Piglets are born without an acquired immune system and an incomplete mucosal immunity therefore rely on immunoglobulin intake from maternal colostrum [ 57 ]. Under commercial conditions, piglets are weaned with an incompletely adapted enteric immune system [ 1 , 57 ].…”

“…Piglets are born without an acquired immune system and an incomplete mucosal immunity therefore rely on immunoglobulin intake from maternal colostrum [ 57 ]. Under commercial conditions, piglets are weaned with an incompletely adapted enteric immune system [ 1 , 57 ]. Our IHC-analysis shows that the number of intraepithelial lymphocytes was higher in the 26-day group than in the 12-day group but the number of intraepithelial lymphocytes is still lower than in adult pigs, suggesting that the development of the intestinal mucosal is not yet complete [ 58 ].…”

A TriAdj-Adjuvanted Chlamydia trachomatis CPAF Protein Vaccine Is Highly Immunogenic in Pigs

“…Based on high similarities regarding size, physiology, reproductive cycles, immunology, and susceptibility to Ct, pigs have been used as biomedical animal models [9][10][11][12], including the study of immunity [13][14][15], STIs [16,17], and Ct vaccine development [18][19][20][21][22]. In addition, pigs can be infected both ocularly [23] and genitally [22,24] with C. suis (Cs).…”

Conserved B cell signaling, activation, and differentiation in porcine jejunal and ileal Peyer's patches despite distinct immune landscapes

“…While non-human primates share more similarities with humans than rodents 33 , increased ethical, financial, and zoonotic disease transmission constraints impede the use of non-human primates as biomedical models. Pig and human intestinal physiology, nutrition, microbiota, and immunity share many similarities 30,32,[34][35][36][37] , and intestinal immune cells, including B cells associated with PPs, have highly conserved transcriptional programs between pigs and humans 38,39 . Moreover, pigs are the largest global dietary animal protein source 40 , and using pigs as a biomedical model exemplifies dual benefits to human and animal health highlighted under the One Health research approach 41 .…”