New insights on molecular pathways utilized by salmonella species in cell binding

Salmonella infections are a principal source of gastroenteritis and enteric fever in a variety of animals, including humans. An essential step in the development of Salmonella pathogenesis is the entry of bacteria into non-phagocytic cells, including those that line the intestinal epithelium. As a consequence of specific cues from the host intestinal micro-environment, Salmonella entry into the intestinal epithelium is the product of a multistep process that culminates in host cell membrane ruffling, and subsequent bacterial uptake. The events that trigger the internalization event appear to require an array of bacterial secreted proteins, exemplified by the formation of bacterial surface appendages (invasomes) which are important for the induction of host-cell signal transduction pathways that lead to membrane ruffling. In addition, during intestinal disease states induced by Salmonella typhimurium, transepithelial migration of neutrophils rapidly follows attachment of the bacteria to the epithelial membrane. Current evidence indicates that the intestinal epithelium plays a key role in orchestrating the inflammatory response to surface attached S. typhimurium. In this review, we explore current insights on the molecular pathways utilized by Salmonella spp. in cell binding that are important not only in the processes of Salmonella internalization but also in the generation of signals which lead to active states of intestinal inflammation.