Lawsonia intracellularis infected enterocytes lack sucrase-isomaltase which contributes to reduced pig digestive capacity

Abstract

Lawsonia intracellularis is endemic to swine herds worldwide, however much is still unknown regarding its impact on intestinal function. Thus, this study aimed to characterize the impact of L. intracellularis on digestive function, and how vaccination mitigates these impacts. Thirty-six L. intracellularis negative barrows were assigned to treatment groups (n = 12/trt): (1) nonvaccinated, L. intracellularis negative (NC); (2) nonvaccinated, L intracellularis challenged (PC); and (3) L. intracellularis challenged, vaccinated (Enterisol® Ileitis, Boehringer Ingelheim) 7 weeks pre-challenge (VAC). On days post-inoculation (dpi) 0 PC and VAC pigs were inoculated with L. intracellularis. From dpi 19–21 fecal samples were collected for apparent total tract digestibility (ATTD) and at dpi 21, pigs were euthanized for sample collection. Post-inoculation, ADG was reduced in PC pigs compared with NC (41%, P < 0.001) and VAC (25%, P < 0.001) pigs. Ileal gross lesion severity was greater in PC pigs compared with NC (P = 0.003) and VAC (P = 0.018) pigs. Dry matter, organic matter, nitrogen, and energy ATTD were reduced in PC pigs compared with NC pigs (P ≤ 0.001 for all). RNAscope in situ hybridization revealed abolition of sucrase-isomaltase transcript in the ileum of PC pigs compared with NC and VAC pigs (P < 0.01). Conversely, abundance of stem cell signaling markers Wnt3, Hes1, and p27Kip1 were increased in PC pigs compared with NC pigs (P ≤ 0.085). Taken together, these data demonstrate that reduced digestibility during L. intracellularis challenge is partially driven by abolition of digestive machinery in lesioned tissue. Further, vaccination mitigated several of these effects, likely from lower bacterial burden and reduced disease severity.

Oral Vaccination Reduces the Effects of Lawsonia intracellularis Challenge on the Swine Small and Large Intestine Microbiome

“…Similar to F. nucleatum, Bacteroides, and B. fragilis also have been implicated in colorectal cancer, in which certain strains have been found to be capable of promoting cellular proliferation by stimulation of Wnt signaling. The latter is a signaling pathway that has also been described to be altered in pigs with PPE (4,(34)(35)(36). Increased abundance of Bacteroides has also been found in the fecal microbiome of pigs challenged with a pure culture of L. intracellularis and to be negatively associated with weight gain in swine (8, 10).…”

Alleviative Effect of Probiotic Ferment on Lawsonia intracellularis Infection in Piglets

“…In fact, it has been shown that LI -challenged pigs had lower ileal sucrase activity [ 30 ]. Helm et al also found that LI -infected enterocytes lack sucrase-isomaltase, contributing to reduced pig digestive capacity [ 32 ]. Bile acids and vitamin B 12 were nutrients absorbed primarily in the ileum, which played an important role in maintaining metabolic homeostasis and regulation [ 33 , 34 ].…”

Comparison of the gut microbiome composition between Lawsonia intracellularis vaccinated and non-vaccinated pigs in a sub-clinically infected pig herd

“…Another strategy against LI infection is vaccination. A live attenuated vaccine against LI was developed and induced immunity against wild type of LI and improvement of host clinical signs as well as higher productivity was observed [3,4]. Besides the clinical onset of proliferative enteropathy, subclinical LI infection also damaged the host intestine and loss of productivity was present [5].…”