Abstract Weaning in conventional pig production is a stressful event that involves abrupt dietary and environmental changes, and the post-weaning period is associated with increased incidence of disease and antibiotic use. As a result, there is a growing demand for non-antibiotic practices to enhance health during this phase of production. Current production systems wean piglets at a relatively young age, and it is unclear if age at weaning impacts shifts in intestinal immune populations, particularly intraepithelial T lymphocyte (T-IEL) populations, or bacterial communities in a comparable timeframe and magnitude. T-IELs reside in the intestinal epithelium and play a role in intestinal integrity and defense. While later weaning may be an approach to minimize the negative impacts of weaning, the impact of age at weaning on T-IEL abundances and function is not clearly understood. Our results indicate pigs weaned at 18–21 days of age (standard weaned, SW), which is consistent with production practices in the United States, had delayed shifts in T-IEL populations when compared to pigs weaned at 25–28 days of age (late weaned, LW), which is consistent with practices in the European Union. Specifically, the abundance of induced T-IELs (CD8ab+ ab T cells) in the jejunum increased between 0 and 3 days post weaning (dpw) for the LW group and stabilized, but shifts were delayed until between 3dpw and 7dpw in the SW group. Concomitant decreases in the abundance of natural T-IEL (gd T cells) were detected. The structure of jejunal mucosal bacterial communities were comparable between SW and LW pigs at 0dpw, but the SW group had more pronounced shifts from 3dpw to 7dpw and 7dpw to 14dpw compared to minimal shift in LW group from 7dpw to 14dpw. Body weight between groups was comparable when adjusted for age. Overall, the bacterial communities of the jejunal mucosa were more stable after weaning in LW than SW pigs, and jejunal T-IEL abundances stabilized more rapidly in the LW group. As T-IELs play a key role in intestinal homeostasis and barrier integrity, the early differences in population abundance may be indicative of functional differences as well.

Atherosclerosis is an inflammatory disorder responsible for cardiovascular disease. Reactivation of efferocytosis, the phagocytic removal of cells by macrophages, has emerged as a translational target for atherosclerosis. Systemic blockade of the key 'don't-eat-me' molecule, CD47, triggers the engulfment of apoptotic vascular tissue and potently reduces plaque burden. However, it also induces red blood cell clearance, leading to anemia. To overcome this, we previously developed a macrophage-specific nanotherapy loaded with a chemical inhibitor that promotes efferocytosis. Because it was found to be safe and effective in murine studies, we aimed to advance our nanoparticle into a porcine model of atherosclerosis. Here, we demonstrate that production can be scaled without impairing nanoparticle function. At an early stage of disease, we find our nanotherapy reduces apoptotic cell accumulation and inflammation in the atherosclerotic lesion. Notably, this therapy does not induce anemia, highlighting the translational potential of targeted macrophage checkpoint inhibitors.
© 2024. The Author(s).

The use of next-generation probiotics (NGP) in pigs for combating diseases has been subject to limited research. Here we explored the potential of a well-known NGP candidate Akkermansia muciniphila targeting pig gut health. In the first screening experiment, we found that the abundance of A. muciniphila peaked at 14 d old but decreased at weaning (21 d old; P < 0.05), suggesting the weaning period may be an effective window for A. muciniphila intervention. Following that, 48 crossbred weaned pigs at 28 d old were randomly assigned to five groups: control (CON), high/low live A. muciniphila (HA/LA), and high/low heat-killed A. muciniphila (HIA/LIA). From 1 to 28 d old, the CON group received gastric infusion of anaerobic sterile saline every other day; the HA and LA groups were gavaged every other day with 1 × 1010 CFU/5 mL and 5 × 108 CFU/5 mL live A. muciniphila, respectively; and the HIA and LIA groups were gavaged every other day with 1 × 1010 CFU/5 mL and 5 × 108 CFU/5 mL heat-killed A. muciniphila, respectively. At d 29, pigs in the CON group were randomly and equally divided into two groups, one of which was named the enterotoxigenic Escherichia coli (ETEC) group, and all groups except CON received a 5-d ETEC challenge. The supplementation of A. muciniphila numerically reduced the diarrhea rate of weaned pigs compared to the pigs that only received the ETEC challenge (P = 0.57), but the LIA group had a higher diarrhea rate than the CON group (P < 0.05). Consistent with this, the supplementation of A. muciniphila improved the small intestinal morphology and structure, proportion of CD4+ T lymphocytes in the blood, as well as the expression of genes related to intestinal barrier and antioxidant indices of pigs with ETEC challenge, especially for the LA group (P < 0.05). Meanwhile, A. muciniphila supplementation reduced the expression of ETEC virulence factor genes in the ileum and colon of pigs challenged by ETEC (P < 0.05). Therefore, A. muciniphila may protect the intestinal health of weaned piglets from damage caused by ETEC infection, but the effect may vary depending on the concentration and activity of A. muciniphila.
© 2024 The Authors.

Vaccine adjuvants are able to boost immune responses and steer immunity towards a desired direction. Liposome-based cationic adjuvant formulations (CAFs) are effective in inducing cell-mediated immune responses in mice, non-human primates and humans. In the translation from mouse to humans, pigs could play an important role. In this study, we thus used commercial pigs housed under field conditions to investigate the effects of four different CAFs incorporating distinct immunomodulators: C-type lectin receptor ligands trehalose-6,6’-dibehenate and monomycolyl glycerol, toll-like receptor ligand Poly(I:C) or retinoic acid. The vaccines were formulated with a recombinant Chlamydia model protein antigen and administered via distinct injection routes. All adjuvants significantly increased antigen-specific IgA and IgG in serum, compared to non-adjuvanted antigen. Administering the vaccines through intramuscular and intraperitoneal routes induced significantly higher antigen-specific IgA and IgG serum antibodies, than the perirectal route. Although the immunizations triggered cell-mediated immunity, no significant differences between the adjuvants or injection sites were detected by intracellular flow cytometry or cytokine-release assays. Genes depicting T cell subtypes were monitored by qPCR, which revealed minor differences only. Our findings suggest that the adjuvant-specific signature of the tested adjuvant immunomodulation does not translate well from mice to pigs. This study provides new insights into immune responses to CAFs in the pig model, and highlights that adjuvant studies should be ideally carried out in the intended species of interest.

Intraepithelial T lymphocytes (T-IELs) are T cells located within the epithelium that provide a critical line of immune defense in the intestinal tract. In pigs, T-IEL abundances and phenotypes are used to infer putative T-IEL functions and vary by intestinal location and age, though investigations regarding porcine T-IELs are relatively limited. In this study, we expand on analyses of porcine intestinal T-IELs to include additional phenotypic designations not previously recognized in pigs. We describe non-conventional CD8α+CD8β- αβ T-IELs that were most prevalent in the distal intestinal tract and primarily CD16+CD27-, a phenotype suggestive of innate-like activation and an activated cell state. Additional T-IEL populations included CD8α+CD8β+ αβ, CD2+CD8α+ γδ, and CD2+CD8α- γδ T-IELs, with increasing proportions of CD16+CD27- phenotype in the distal intestine. Thus, putative non-conventional, activated T-IELs were most abundant in the distal intestine within multiple γδ and αβ T-IEL populations. A comparison of T-IEL and respective mucosal microbial community structures across jejunum, ileum, and cecum of 5- and 7-week-old pigs revealed largest community differences were tissue-dependent for both T-IELs and the microbiota. Between 5 and 7 weeks of age, the largest shifts in microbial community compositions occurred in the large intestine, while the largest shifts in T-IEL communities were in the small intestine. Therefore, results indicate different rates of community maturation and stabilization for porcine T-IELs and the mucosal microbiota for proximal versus distal intestinal locations between 5 and 7 weeks of age. Collectively, data emphasize the intestinal tract as a site of location- and age-specific T-IEL and microbial communities that have important implications for understanding intestinal health in pigs.
Published by Elsevier Ltd.