Journal of Clinical and Cellular Immunology
Open Access

Abstract

Innate Immune Response to Urinary Tract Infections Involving Escherichia coli

Wanda C. Reygaert

The innate immune system responds in a rapid, initially nonspecific manner to infection in the urinary tract. There are many molecules and cells involved in this response. These include: antimicrobial peptides, toll-like receptors, chemokines, cytokines, and neutrophils. The most common cause of urinary tract infections (UTIs) are uropathogenic Escherichia coli (UPEC). The innate immune system responds to the presence of flagella, fimbriae, and the lipopolysaccharide outer membrane of these bacteria. Antimicrobial peptides are used to lyse the bacteria and also prevent the bacteria from binding to epithelial cells in the urinary tract. The toll-like receptors sense the presence of the bacteria and signal for the production of molecules that cause immune and inflammation responses. The various chemokines and cytokines such as CXCL8, CCL2, interleukins (IL-6, IL-8, IL-10, IL-17A), and granulocyte colony stimulating factor (G-CSF), are used for much of the signaling in innate immunity. In addition, neutrophils play a major role in rapid removal of invading bacteria. The rapid innate immune response is designed to remove most of the bacteria within 24 hours in an uncomplicated UTI. This review presents an overview of the innate immune response to UTIs caused by UPEC and the host molecules and cells involved.