Flu and immunomodulators : lights and shadows

The intestinal microbiota is an ecosystem formed by a variety of ecological niches, made of several bacterial species and a very large amount of strains. The microbiota is in close contact with the intestinal mucosa or epithelial interface which is, after the respiratory area, the largest surface of the body, occupying approximately 250-400 m2. The physiological activities of the microbiota are manifold and are just being unraveled. Based on the observations of the multiple roles played by the microbiota in health and disease, the notion of modifying it with appropriate formulations, i.e. probiotics, is being tested in several settings. This review summarizes the current knowledge on probiotics and discusses both limitations and acquired evidence to support their use in preventive and therapeutic medicine. As mentioned, all probiotics induce an immune response, whose characteristics are related to the strain or the combination of bacteria that have been used. Recent studies have shown positive effects of probiotics on the respiratory system, especially in preventing and reducing the severity of respiratory infections, due to an increase in IgA-secreting cells in the bronchial mucosa. The role of malnutrition and deficiency of some micronutrients and vitamins has also been demonstrated in the process of viral pathogens cell entry and replication. The preventive use of supplements containing substances active on the immune system plays an important role both before vaccination and as adjuvant in vaccines, to increase antibodies. in the elderly and debilitated subjects. Hereafter, we present the results of studies performed on different target populations aimed at investigating the effects of probiotics on infectious diseases of the respiratory system.