The role of toll-like receptors (TLRs) in urinary tract infections (UTIs)

INTRODUCTION: Urinary Tract Infections (UTIs) are caused by different types of microbial agents such as uropathogenic Escherichia coli (UPEC) and Candida albicans. The presence of strong physical barriers may prevent the breach of pathogens into the urinary tract. However, sometimes the pathogenic microorganisms may pass through the barriers and stimulate the innate and adaptive responses. Among a variety of innate immune responses, Toll-Like Receptors (TLRs) are one of the most unique and interesting molecules regarding UTIs. Thus, the authors have focused their attention on the role of TLRs in urinary tract defense against pathogenic microbial agents such as UPEC and C.albicans through this literature review. MATERIAL AND METHODS: Several papers regarding UTIs and TLRs including original and review articles were searched by PubMed and Google Scholar. They were studied and the most important aspects in association with the role of TLRs in UTIs were extracted. Additionally, this paper was prepared using the experience of the authors. RESULTS: The TLRs 2, 4 and 5 are the most functional molecules that contribute to urinary tract defense system and UTIs. It is incredible that TLRs are able to detect and recognize different parts of microbial components relating to the same pathogen. Besides, the flexibility of the TLR molecules may lead to identification of different types of microorganisms with different signaling pathways. CONCLUSIONS: Our knowledge associated with TLRs and their activities against microbial causative agents of UTIs may help us to prevent, control and treat UTIs at a higher quality level.