The gastrointestinal tract of mammals is inhabited by several hundred bacterial species. The importance Pig. of understanding the relationships between mammals and their resident microbial populations has been emphasized for over 100 years. Disruption of the intestinal homeostasis and tolerance towards the commensal microbiota is a major mechanism involved in the development of many civilization disorders.

Laboratory assistant.

Only gnotobionts - germ-free or animals colonized with defined microbiota could help us to understand both the generality and specificity of the relationship between a host and bacterial components. Forty years ago we established in our laboratory gnotobiology colonies of germ-free rats, mice, rabbits as well as piglets which are used in our experiments.

The goals of our projects are to study the effects of bacterial component of the intestinal microbiota on Animal room. the development of experimental models of human diseases which development is supposed to be a consequence of disturbed microbiota (inflammatory bowel diseases, allergies, atherosclerosis). Prevalence of allergic disorders in western countries has been linked to the high hygienic standards associated with a reduced microbial stimulation affecting mucosal immune system. Whereas some bacteria are inducers of several diseases, others, known as probiotics, have protective effects. These include the development of lymphocyte subpopulations in central, peripheral and mucosal lymphatic tissues. Antibody responses as well as cytokine profiles and the levels of brush border enzymes are investigated in fetal and newborn pigs, mice and rats. The regulation of innate immune responses against enteropathogenic E. coli and Salmonella is studied in gnotobiotic piglets.

Rats.

Very important studies are performed in ontogeny of porcine lymphocyte subsets. The ability to identify factors responsible for disease in all species depends on the ability to separate those factors which are environmental from those that are intrinsic. This is particularly important for studies on the development of the adaptive immune response of neonates. Cellular and humoral aspects of the immune response develop sequentially in the fetus. Basic questions including the identification of the first lympho-hematopoietic sites, the origin of T and B lymphocytes, the development of different subpopulations of alpha/beta T, gamma/delta T and B lymphocytes as well as development of innate immunity and the acquisition of full developed immune responses are studied. Studies on swine aided our understanding of passive immunity and provide opportunities to use swine to address specific issues in veterinary and biomedical research and immunotherapy.