The Mycotoxin Deoxynivalenol Potentiates Intestinal Inflammation by Salmonella Typhimurium in Porcine Ileal Loops

Background and Aims: Both deoxynivalenol (DON) and nontyphoidal salmonellosis are emerging threats with possible hazardous effects on both human and animal health. The objective of this study was to examine whether DON at low but relevant concentrations interacts with the intestinal inflammation induced by Salmonella Typhimurium. Methodology: By using a porcine intestinal ileal loop model, we investigated whether intake of low concentrations of DON interacts with the early intestinal inflammatory response induced by Salmonella Typhimurium. Results: A significant higher expression of IL-12 and TNF alpha and a clear potentiation of the expression of IL-1 beta, IL-8, MCP-1 and IL-6 was seen in loops co-exposed to 1 mu g/mL of DON and Salmonella Typhimurium compared to loops exposed to Salmonella Typhimurium alone. This potentiation coincided with a significantly enhanced Salmonella invasion in and translocation over the intestinal epithelial IPEC-J2 cells, exposed to non-cytotoxic concentrations of DON for 24 h. Exposure of Salmonella Typhimurium to 0.250 mu g/mL of DON affected the bacterial gene expression level of a limited number of genes, however none of these expression changes seemed to give an explanation for the increased invasion and translocation of Salmonella Typhimurium and the potentiated inflammatory response in combination with DON. Conclusion: These data imply that the intake of low and relevant concentrations of DON renders the intestinal epithelium more susceptible to Salmonella Typhimurium with a subsequent potentiation of the inflammatory response in the gut

Quantification of proliferating lymphocyte subsets appearing in the intestinal lymph and the blood

Lymphocyte emigration from the intestinal wall via lymphatics is necessary to maintain gastrointestinal immunity and also to connect the different parts of the mucosal immune system. In the present study the numbers and time kinetics of proliferating lymphocyte subsets leaving the gut wall via intestinal lymphatics were analysed in mesenteric lymph node adenectomized minipigs (n = 8). After cannulation of the major intestinal lymph duct, afferent lymph was collected under non-restraining conditions. In four pigs lymphocytes taken from the intestinal lymph and blood were incubated in vitro with the thymidine analogue bromodesoxyuridine (BrdU) to label all lymphocytes in the S-phase of the cell cycle. The other four pigs received a single i.v. injection of BrdU 1 week after cannulation. The initial percentage of BrdU+ lymphocyte subsets in the intestinal lymph 15 min after BrdU injection was comparable to that after the in vitro labelling (1.5 ± 0.7% in T cells, 10.6 ± 1.6% in IgM+ cells and 30.0 ± 11.9% in IgA+ cells). From this level onwards, the percentage of in vivo labelled BrdU+ lymphocyte subsets reached a maximum at 12 h after BrdU application. A different pattern of BrdU+ subsets was seen in the blood. After an early peak at around 3–4 h, the frequency of BrdU in vivo labelled cells decreased. Each subset had a maximum between 12 h and 48 h after BrdU application (maximum of BrdU+ CD2+ T cells at 12 h, 4.6 ± 1.5%; IgM+ BrdU+ at 48 h, 8.8 ± 3.3%). The present results provide a basis to determine the time necessary for induction of specific intestinal immunity during oral vaccination studies

Effects of microflora on the neonatal development of gut mucosal T cells and myeloid cells in the mouse

Colonization with commensal flora in very early life may profoundly influence intestinal lymphoid development and bias later immune responses. We defined gut-homing T cell phenotypes and the influence of flora on intestinal immune development in mice. Intestinal T cells were phenotyped and quantified in conventional (CV), germfree (GF) and conventionalized germfree (GF/CV) neonatal mice by immunohistochemistry. Mucosal adressin cell adhesion molecule 1 (MAdCAM-1) was expressed by mucosal vessels at birth in CV and GF mice and was more prevalent in CV than GF small intestine, but was distributed similarly and did not change with age. Less MAdCAM-1 was expressed in the colon; its distribution became restricted after weaning, with no difference between CV and GF mice. CD3+β7+ cells were present in similar numbers in CV and GF intestine at birth. They were CD62L– in CV mice and were accompanied by further CD3+β7+CD62L– T cells as development progressed, but in GF and GF/CV intestine they expressed CD62L and numbers did not change. IEL numbers increased at weaning in CV mice in both small and large intestine, but showed delayed development in GF intestine. Macrophages were present at high levels from birth in GF intestine, but dendritic cells did not develop until day 16. Thus, fetus-derived T cells seed the intestinal lamina propria before birth via β–MadCAM interactions. Their activation status depends on the microbiological status of the dam, and without a commensal flora they remain naive. We propose that these cells regulate antigen responsiveness of the developing mucosal T cell pool

Probiotics and prebiotics in inflammatory bowel disease: microflora ‘on the scope’

The intestinal microflora is a large bacterial community that colonizes the gut, with a metabolic activity equal to an organ and various functions that affect the physiology and pathology of the host's mucosal immune system. Intestinal bacteria are useful in promotion of human health, but certain components of microflora, in genetically susceptible individuals, contribute to various pathological disorders, including inflammatory bowel disease. Clinical and experimental observations indicate an imbalance in protective and harmful microflora components in these disorders. Manipulation of gut flora to enhance its protective and beneficial role represents a promising field of new therapeutic strategies of inflammatory bowel disease. In this review, we discuss the implication of gut flora in the intestinal inflammation that justifies the role of probiotics and prebiotics in the prevention and treatment of inflammatory bowel disease and we address the evidence for therapeutic benefits from their use in experimental models of colitis and clinical trials

Postnatal leptin promotes organ maturation and development in IUGR piglets

Babies with intra-uterine growth restriction (IUGR) are at increased risk for experiencing negative neonatal outcomes due to their general developmental delay. The present study aimed to investigate the effects of a short postnatal leptin supply on the growth, structure, and functionality of several organs at weaning. IUGR piglets were injected from day 0 to day 5 with either 0.5 mg/kg/d leptin (IUGRLep) or saline (IUGRSal) and euthanized at day 21. Their organs were collected, weighed, and sampled for histological, biochemical, and immunohistochemical analyses. Leptin induced an increase in body weight and the relative weights of the liver, spleen, pancreas, kidneys, and small intestine without any changes in triglycerides, glucose and cholesterol levels. Notable structural and functional changes occurred in the ovaries, pancreas, and secondary lymphoid organs. The ovaries of IUGRLep piglets contained less oogonia but more oocytes enclosed in primordial and growing follicles than the ovaries of IUGRSal piglets, and FOXO3A staining grade was higher in the germ cells of IUGRLep piglets. Within the exocrine parenchyma of the pancreas, IUGRLep piglets presented a high rate of apoptotic cells associated with a higher trypsin activity. In the spleen and the Peyer’s patches, B lymphocyte follicles were much larger in IUGRLep piglets than in IUGRSal piglets. Moreover, IUGRLep piglets showed numerous CD79+cells in well-differentiated follicle structures, suggesting a more mature immune system. This study highlights a new role for leptin in general developmental processes and may provide new insight into IUGR pathology