[Fifth revolution in medicine: on the role of infections in pathogenesis of aging and chronic diseases].

The XXth century is marked by the substantial increase in human life expectancy. Historically, main reasons for that are four achievements of medicine: (1) improvements in common hygiene, such as waste disposal and water purification which led to the significant reduction of communicable diseases; (2) common recognition of Pasteur's Germ Theory followed by improvements in occupational and personal hygiene as well as introduction of antiseptic and aseptic measures; (3) decrease in childhood mortality due to the discovery and widespread application of vaccination; and (4) the discovery and clinical application of antibiotics. An epidemiological transition took place, i.e. the shift from communicable infectious diseases, as a main cause of morbidity and mortality, to chronic degenerative diseases, mainly considered non-infectious. Experimental evidence has been accumulated on a significant number of microorganisms, including viruses (such as a group of herpes viruses, hepatitis viruses, etc.), bacteria (Chlamydia, Helicobacter, periodontal pathogens, etc.), fungi and parasites, as an underlying reason for many of diseases, such as atherosclerosis, various cancers, type 1 and 2 diabetes, neurodegenerative and some psychiatric diseases, osteoporosis, autoimmune diseases and others. On the other hand, most of these diseases have been traditionally associated with age, together with other "age-related" disorders, such as immune system suppression, thymus involution, pathologic calcification, etc. Taken together, these facts suggest that aging, among others, has infectious origins, and that burden of infections may lead to enhanced senescence and premature death. In fact, infections may serve as a trigger of senescence, presumably via the mechanisms of chronic oxidative stress, low-grade inflammation, telomere shortening, and autoimmune processes due to the molecular mimicry. We believe that next step in human longevity increase can be possible by common appreciation of the role of infections as the main trigger of age-related diseases and disorders, and by efforts to cure and/or eradicate these infections.

[Age-related aspects of intestinal microflora and the intestinal immune system].

The importance of influence of microorganisms on human health has been recognized for years. Vast amount of data has been collected regarding interaction of intestinal microflora and elements of gut immune system. Novel technologies are offering new insights into bi-directional host-flora exchange along mucosal surfaces, one of the largest interfaces of human organism. Gut is constantly being colonized through our life, therefore, mucosal immune responses require capacity to resist pathogenic bacteria. Yet gut bacterial community has a collective metabolic activity equal to a virtual organ, and the interplay between food, host cells and microbes is indispensable for shaping both innate and adaptive immunity. Age-related changes of gut microflora are well recognized, however, little is known about the feedback effect. We hypothesize that altered intestinal microflora influences mucosal immunity what in turn promotes changes on organismic level leading to further compositional and functional shifts in the microbiota. The aim of this review is to analyze current literature on the impact of such feedback. Understanding this vicious circle will ultimately lead us to better managing of number of infectious, inflammatory and neoplastic disease processes.