Preconditioned suppression of prolyl-hydroxylases attenuates renal injury but increases mortality in septic murine models.

Background: Septic conditions contribute to tissue hypoxia, potentially leading to multiple organ failure, including acute kidney injury. The regulation of cellular adaptation to low oxygen levels is regulated by hypoxia-inducible transcription factors (HIFs). While the role of HIFs in ischaemia/reperfusion is more studied, their function in sepsis-induced renal injury is not well characterized. In this study, we investigated whether pharmacological activation of HIFs by suppression of prolyl-hydroxylases (PHDs) protects against septic acute kidney injury.

Methods: Two models of sepsis-caecal ligation and punction and peritoneal contamination and infection-were induced on 12-week-old C57BL6/J mice. Pharmacological inhibition of PHDs, leading to HIF activation, was achieved by intraperitoneal application of 3,4-dihydroxybenzoate (3,4-DHB) before sepsis. A quantitative real-time reverse transcription polymerase chain reaction, immunohistology and enzyme-linked immunosorbent assays were utilized to detect gene expression, renal protein levels and renal functional parameters, respectively. Tissue morphology was analysed by periodic acid-Schiff reaction. Early kidney injury was estimated by kidney injury molecule-1 analyses. Apoptosis was detected in situ by terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling stain. The systemic effect of 3,4-DHB pretreatment in sepsis was analysed by 72-h survival studies.

Results: Pharmacological activation of HIFs before sepsis induction attenuated sepsis-related vacuolization and dilation of the proximal tubules, reduced tubular apoptosis and correlated to lower T-cell infiltration in renal tissue compared with the non-treated septic animals. PHD suppression elevated the basal renal HIF-1α expression and basal plasma concentrations of HIF targets erythropoietin and vascular endothelial growth factor. Whereas it preserved renal structure in both models, it improved renal function in a model-dependent manner. Moreover, inhibition of PHDs led to increased mortality in both models. Analysis of liver function showed increased organ destruction with massive glycogen loss and hepatocyte's apoptosis due to 3,4-DHB administration before sepsis induction.

Conclusions: In summary, the pharmacological activation of HIFs by 3,4-DHB administration, although it showed renoprotective effects in sepsis-related kidney injury, induced more severe problems in other organs such as the liver during sepsis, leading to increased mortality.