Probiotic Induced Immunomodulation: Investigation into the Cellular and Molecular Mechanishm Involved

Abstract

Commensalisms or symbiosis or the concept of probiosis is a prospective outcome of the dynamic co evolution of host-bacterial relationships. The use of antibiotics is discouraged in aquaculture as it has led to the appearance of drug-resistant bacteria, immunosuppression in animals besides harmful effects on the environment and concerns on food safety. Strain specific immunomodulation by probiotic bacteria was determined experimentally. The feeding of different strains of probionts Lactbacillus rhamnosus, Bacillus subtilis, Eterococcous faecium was found to influence immune response both at local and systemic level. The non-specific cellular immune response increased with probiotic feeding as reflected in the increase of phagocytosis and super oxide anion of head kidney leucocytes in rainbow trout and humoral response as lysozyme activity. The upregulation of cytokines like, Interleukin (IL1), Tumor necrosis factor (TNF), Transforming growth factor (TGF) isolated from head kidney leucocytes and other tissues of the probiotic fed groups were observed compared to that of the control fish. Cytokines induced by these probionts may thus be important regulators of gut-associated immune system. Probiotic as a factor for immunomodulation including the immune gene modulation which in turn is correlated to the health status of this lower vertebrates, could probably be explored for developing alternate health management strategy in aquaculture.