1. ¹Renal Diagnostics and Therapeutics Unit, NIDDK, NIH, Bethesda, MD, USA
2. ²Laboratory of Parasitic Diseases, Immunobiology Section, NIAID, NIH, Bethesda, MD, USA
3. ³Tissue Array Research Program, Laboratory of Pathology, Center for Cancer Research, NCI, NIH, Bethesda, MD, USA

Correspondence: RA Star, Renal Diagnostics and Therapeutics Unit, NIDDK, 10 Center Drive, Building 10, Room 3N108, Bethesda, MD 20892-1268, USA. E-mail: Robert_Star@nih.gov

⁴Current address: Clinical Pharmacology Unit, Room E3.23, Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, UK.

Received 12 August 2005; Revised 10 October 2005; Accepted 28 October 2005; Published online 11 January 2006.

Abstract

Toll-like receptors (TLRs) are important in sepsis. Myeloid differentiation factor 88 (MyD88) is a key molecule involved in signal transduction by multiple TLRs. The objective of this study was to investigate the contribution of TLR4 and MyD88 to acute renal failure (ARF) induced by polymicrobial sepsis. Liver dysfunction and apoptosis in the spleen contribute to sepsis severity after cecal ligation and puncture (CLP). Therefore, we also investigated liver injury and splenic apoptosis. We used a mouse model of sepsis-induced ARF using CLP to generate polymicrobial sepsis. Despite fluid and antibiotic resuscitation the mice developed multi-organ failure, including ARF, which resembles human sepsis. We investigated the role of the TLR4 receptor by comparing C3H/HeJ mice (which lack TLR4) with C3H/He0UJ normal controls. The role of MyD88 was investigated by comparing MyD88 knockout mice (MyD88^-/-) with wild-type controls. Following CLP, mice lacking TLR4 and wild-type mice both developed comparable ARF. However, MyD88^-/- mice did not develop ARF compared to wild-type controls. In contrast, MyD88^-/- mice developed liver injury comparable to wild type. After CLP, MyD88^-/- mice had significantly reduced apoptosis in the spleen compared with wild type. Apoptosis was not detected in the kidney of wild-type or MyD88^-/- mice after CLP. In summary, ARF induced by polymicrobial sepsis is dependent on MyD88, but not TLR4. The absence of MyD88 dissociates ARF from liver injury; liver injury is MyD88-independent. There was MyD88-dependent apoptosis in the spleen, but no apoptosis in the kidney. MyD88 may be a good drug target for some, but not all, organ dysfunctions following sepsis.