Factors of immune protection in the pathogenesis of urinary infections (literature review)

Abstract

In recent years, ideas about the pathogenesis of urinary tract infections have been changed significantly. Various pathogenetic factors of microorganisms and new defense mechanisms against them have been discovered. A significant part of pathogens is inactivated by the first line of defense - innate immunity which includes epithelial barriers (mucous membranes), cellular (phagocytes, dendritic cells, NK-cells) and humoral (chemokines, cytokines, complement) components, as well as antimi­crobial proteins). The second and more specific line of defense is the acquired (adaptive) immune system - humoral (B-cells, antibodies) immunity and cellular (T-cells) immunity. However, epithelial cells play an important role in the immune response. These cells interact with the components of both innate immunity and acquired one. Antimicrobial proteins are one of the most ancient and primitive components of the immune system and they are very widely spread in nature. More than 800 antimicro­bial proteins have been described and more than 100 of them have been found in the human body. The mechanism of these proteins is mainly connected with the violation of the bacterial membrane integrity. Nevertheless, some proteins can inhibit protein and/or DNA synthesis. The most common protein in the urine is uromodulin (Tamm-Horsfall protein), synthesized in the thick ascending section of the Henle loop. Uromodulin does not have direct antimicrobial activity, but it is involved in the pathogenesis of many inflammatory kidney diseases. In addition, uromodulin acting through the TLR4 signaling pathway pro­motes the maturation of dendritic cells, thereby further activating innate and acquired immunity. Currently, the role of antimi­crobial proteins and dendritic cells in the pathogenesis of the infectious process is being actively studied. It will probably have a significant practical value. Thus, the development of urinary tract infections is the process of competing for the interaction of the uropathogenic and the macroorganism. The treatment of these diseases (especially chronic) should not be limited to the use of antibacterial drugs. An important component of the pathogen eradication is to increase the activity of its own protective mechanisms.