title: Distinct pathophysiologic mechanisms of septic acute kidney injury: role of immune suppression and renal tubular cell apoptosis in murine model of septic acute kidney injury.
abstract: OBJECTIVE
  Sepsis is the most common cause of acute kidney injury in critically ill patients; however, the mechanisms leading to acute kidney injury in sepsis remain elusive. Although sepsis has been considered an excessive systemic inflammatory response, clinical trials that inhibit inflammation have been shown to have no effect. The purpose of this study was to examine the pathophysiology of septic acute kidney injury focusing on immune responses and renal tubular cell apoptosis by providing an on-site quantitative comparison between septic- and ischemia/reperfusion-induced acute kidney injury.
  
  
  METHODS
  Twenty-four hours after cecal ligation and puncture or ischemia/reperfusion injury, biochemical, histologic, and cytokine changes were compared in C57BL/6 mice. Apoptosis was assessed, and the effect of caspase 3 inhibition on renal function was also examined. The percentage of regulatory T cells and the effect of depletion were determined and compared with ischemia/reperfusion-induced acute kidney injury. The effect of interleukin-10 blocking was also compared.
  
  
  RESULTS
  Despite comparable renal dysfunction, acute tubular necrosis or inflammation was minimal in septic kidneys. However, tubular cell apoptosis was prominent, and caspase 3 activity was positively correlated with renal dysfunction. A decrease in apoptosis by caspase 3 inhibitor resulted in attenuation of renal dysfunction. In assessment of systemic immunity, septic acute kidney injury was associated with an increase in interleukin-10, and also showed massive immune cell apoptosis with increased regulatory T cells. In contrast to ischemia/reperfusion injury in which depletion of regulatory T cells aggravated renal injury, depletion of regulatory T cells before cecal ligation and puncture resulted in renoprotection. In addition, blocking interleukin-10 rescued septic mice from the development of acute kidney injury, whereas it had no effect in ischemia/reperfusion injury.
  
  
  CONCLUSIONS
  Pathogenesis of septic acute kidney injury is thought to be different from that of ischemia/reperfusion-induced acute kidney injury. Our data showed a link between apoptosis, immune suppression, and the development of acute kidney injury during sepsis and suggest that strategies targeting apoptosis or enhancing immunity might be a potential therapeutic strategy for septic acute kidney injury.
authors.affiliation: Department of Internal Medicine, Division of Nephrology, Eulji General Hospital, Eulji University College of Medicine, Seoul, Korea.
authors.forename: So-Young
authors.initials: SY
authors.lastname: Lee
authors.forename: Yong-Su
authors.initials: YS
authors.lastname: Lee
authors.forename: Hye-Min
authors.initials: HM
authors.lastname: Choi
authors.forename: Yoon-Sook
authors.initials: YS
authors.lastname: Ko
authors.forename: Hee-Young
authors.initials: HY
authors.lastname: Lee
authors.forename: Sang-Kyung
authors.initials: SK
authors.lastname: Jo
authors.forename: Won-Yong
authors.initials: WY
authors.lastname: Cho
authors.forename: Hyoung-Kyu
authors.initials: HK
authors.lastname: Kim
mesh_terms: D058186:Acute Kidney Injury / Q000276:immunology / Q000473:pathology / Q000503:physiopathology*; D000818:Animals; D017209:Apoptosis / Q000276:immunology; D053148:Caspase 3 / Q000378:metabolism; D004195:Disease Models, Animal; D005434:Flow Cytometry; D007165:Immunosuppression Therapy; D016753:Interleukin-10 / Q000378:metabolism; D007684:Kidney Tubules / Q000473:pathology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D015427:Reperfusion Injury; D018805:Sepsis / Q000150:complications*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology
chemical_list: D016753:Interleukin-10; D053148:Caspase 3