bay-11-7082 and Acute-Kidney-Injury

Oxygen homeostasis disturbances play a critical role in the pathogenesis of acute kidney injury (AKI). The transcription factor hypoxia-inducible factor-1 (HIF-1) is a master regulator of adaptive responses to hypoxia. Aside from posttranslational hydroxylation, the mechanism of HIF-1 regulation in AKI remains largely unclear. In this study, the mechanism of HIF-α regulation in AKI was investigated. We found that tubular HIF-1α expression significantly increased at the transcriptional level in ischemia-reperfusion-, unilateral ureteral obstruction-, and sepsis-induced AKI models, which was closely associated with macrophage-dependent inflammation. Meanwhile, NF-κB, which plays a central role in the inflammation response, was involved in the increasing expression of HIF-1α in AKI, as evidenced by pharmacological modulation (NF-κB inhibitor BAY11-7082). Mechanistically, NF-κB directly bound to the HIF-1α promoter and enhanced its transcription, which occurred not only under hypoxic conditions but also under normoxic conditions. Moreover, the induced HIF-1α by inflammation protected against tubular injury in AKI. Thus, our findings not only provide novel insights into HIF-1 regulation in AKI but also offer to understand the pathophysiology of kidney diseases.

Topics: Acute Kidney Injury; Animals; Cells, Cultured; Epithelial Cells; Gene Expression Regulation; Hypoxia-Inducible Factor 1, alpha Subunit; Inflammation; Kidney; Mice; NF-kappa B; Nitriles; Sulfones

Paraquat can result in dysfunction of multiple organs after ingestion in human. However, the mechanisms of nucleotide-binding domain and leucine-rich repeat containing protein 3 (NLRP3) inflammasome activation in acute kidney injury have not been clearly demonstrated. The aim of this study was to determine the effect of NLRP3 inflammasome activation and its regulation by nuclear factor-kappa B (NF-κB) and death-associated protein kinase (DAPK). Male Wistar rats were treated with intraperitoneal injection of paraquat at 20 mg/kg, and NF-κB inhibitor BAY 11-7082 was pretreated at 10 mg/kg 1 h before paraquat exposure. Additionally, rat renal tubular epithelial cells (NRK-52E) were transfected with small interfering RNA (siRNA) against DAPK to evaluate its role in NLRP3 inflammasome activation. DAPK and NLRP3 inflammasome were evaluated by immunohistochemistry staining or Western blot; the pro-inflammatory cytokines including tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), and interleukin-18 (IL-18) were measured via ELISA. The results showed that NF-κB, DAPK, and NLRP3 inflammasome were activated in paraquat (PQ)-treated rat kidney; the secretion of pro-inflammatory cytokines was significantly increased. These toxic effects were attenuated by NF-κB inhibitor. Besides, the activation of NLRP3 inflammasome and secretion of IL-1β and IL-18 in paraquat-treated rat renal tubular epithelial cells were inhibited by siRNA against DAPK. In conclusion, NLRP3 inflammasome activation regulated by NF-κB and DAPK played an important role in paraquat-induced acute kidney injury.

Topics: Acute Kidney Injury; Animals; Cells, Cultured; Cytokines; Death-Associated Protein Kinases; Epithelial Cells; Humans; Inflammasomes; Inflammation Mediators; Kidney Tubules; Male; NF-kappa B; Nitriles; NLR Family, Pyrin Domain-Containing 3 Protein; Paraquat; Rats; Rats, Wistar; RNA, Small Interfering; Sulfones

Despite advancements in renal replacement therapy, the mortality rate for acute kidney injury (AKI) remains unacceptably high, likely due to remote organ injury. Kidney ischemia-reperfusion injury (IRI) activates cellular and soluble mediators that incite a distinct pulmonary proinflammatory and proapoptotic response. Tumor necrosis factor receptor 1 (TNFR1) has been identified as a prominent death receptor activated in the lungs during ischemic AKI. We hypothesized that circulating TNF-α released from the postischemic kidney induces TNFR1-mediated pulmonary apoptosis, and we aimed to elucidate molecular pathways to programmed cell death. Using an established murine model of kidney IRI, we characterized the time course for increased circulatory and pulmonary TNF-α levels and measured concurrent upregulation of pulmonary TNFR1 expression. We then identified TNFR1-dependent pulmonary apoptosis after ischemic AKI using TNFR1-/- mice. Subsequent TNF-α signaling disruption with Etanercept implicated circulatory TNF-α as a key soluble mediator of pulmonary apoptosis and lung microvascular barrier dysfunction during ischemic AKI. We further elucidated pathways of TNFR1-mediated apoptosis with NF-κB (Complex I) and caspase-8 (Complex II) expression and discovered that TNFR1 proapoptotic signaling induces NF-κB activation. Additionally, inhibition of NF-κB (Complex I) resulted in a proapoptotic phenotype, lung barrier leak, and altered cellular flice inhibitory protein signaling independent of caspase-8 (Complex II) activation. Ischemic AKI activates soluble TNF-α and induces TNFR1-dependent pulmonary apoptosis through augmentation of the prosurvival and proapoptotic TNFR1 signaling pathway. Kidney-lung crosstalk after ischemic AKI represents a complex pathological process, yet focusing on specific biological pathways may yield potential future therapeutic targets.

Topics: Acute Kidney Injury; Animals; Apoptosis; Capillary Permeability; CASP8 and FADD-Like Apoptosis Regulating Protein; Caspase 3; Caspase 8; Creatinine; Etanercept; Immunoglobulin G; Ischemia; Kidney; Lung; Lung Injury; Male; Mice; Mice, Inbred C57BL; NF-kappa B; Nitriles; Protein Isoforms; Receptors, Tumor Necrosis Factor; Receptors, Tumor Necrosis Factor, Type I; Reperfusion Injury; Signal Transduction; Sulfones; Tumor Necrosis Factor-alpha