Nice work everyone. This is a growing field in nephrology. Please see the recent Nature Review Nephrology review on Toll like receptors and kidney disease. In general, these receptors recognize pathogen associated molecular patterns and molecules that are released from damaged cells. They are key players in innate immunity, and also play a role in adaptive immunity. They are expressed in variety of immune cells including mast cells, macrophages, dendritic cells, T and B lymphocytes and granulocytes. Overactivation, not underactivation of these receptors might contribute to pathogenesis of few renal diseases such as rejection, immune complex glomerulonephritis, ischemic ATN and perhaps even UTIs and renal leptospirosis.
Some recent data also suggests some role of TLR inhibitors as a therapy for above diseases.
Image source: Nature Review Immunology.
Good reference: http://www.ncbi.nlm.nih.gov/pubmed/20177402