Role of Blood-Brain barrier in bacterial translocation

Abstract

The blood–brain barrier (BBB) is a highly selective, semi-permeable barrier that separates the circulating blood from the brain and extracellular fluid in the central nervous system (CNS). Its primary function is to protect the brain from pathogens and toxins while allowing the passage of essential nutrients and gases. Bacterial translocation, the process by which bacteria move from the gut or other peripheral sites to normally sterile tissues, including the CNS, poses a significant challenge to the integrity of the BBB. This paper explores the role of the BBB in bacterial translocation, emphasizing its defense mechanisms and the conditions under which these defenses can be compromised. In normal physiological conditions, the BBB employs tight junctions between endothelial cells, active efflux transport systems, and metabolic barriers to prevent bacterial entry. However, certain bacteria have evolved mechanisms to breach the BBB, including the production of enzymes that degrade tight junction proteins, receptor-mediated transcytosis, and the induction of inflammatory responses that weaken BBB integrity. So, advances in this field may lead to novel therapeutic approaches that enhance BBB integrity or inhibit bacterial translocation mechanisms, thereby reducing the incidence and severity of bacterial infections in the brain.