Role of OPG/RANKL/RANK/TLR4 signaling pathway in sepsis-associated acute kidney injury.

Sepsis-associated acute kidney injury (SA-AKI) has high mortality rates. The osteoprotegerin (OPG)/receptor activator of nuclear factor-κB ligand (RANKL)/receptor activator of nuclear factor-κB (RANK)/Toll-like receptor 4 (TLR4) pathway and its potential role in SA-AKI pathogenesis remain to be fully understood. Herein, we addressed this issue using mouse models. An SA-AKI mouse model was established using the cecal ligation and puncture method (CLP). Mice were grouped into sham, CLP model, CLP + recombinant RANKL, and CLP + anti-RANKL groups. Serum creatinine (Scr) and blood urea nitrogen (BUN) levels were measured to assess kidney function. ELISA was used to detect serum IL-1β, TNF-α, and IL-6 levels. Real-time quantitative PCR and Western blot were used to detect the mRNA and protein expression levels of OPG, RANKL, RANK, and TLR4 in kidney tissues. HE staining was performed to evaluate the pathological changes. The CLP model group showed higher levels of Scr and BUN, indicating impaired kidney function in SA-AKI, compared to the sham group. Treatment with recombinant RANKL in the CLP + recombinant RANKL group reduced Scr and BUN levels, while anti-RANKL treatment in the CLP + anti-RANKL group elevated their levels. Moreover, the CLP model group had significantly increased IL-1β, TNF-α, and IL-6 than the sham group, indicating elevated inflammation in SA-AKI. The CLP + recombinant RANKL group demonstrated decreased cytokine levels, whereas the CLP + anti-RANKL group showed an increase. Additionally, the histopathological evaluation revealed distinct kidney tissue damage in the CLP model group. Recombinant RANKL treatment reduced this damage, while anti-RANKL treatment exacerbated it. Mechanically, the mRNA and protein expression of RANKL were significantly decreased, while those of OPG, RANK, and TLR4 were significantly increased in the CLP model group and the CLP + anti-RANKL group. Interestingly, treatment with recombinant RANKL reversed these changes, as evidenced by significantly increased RANKL but decreased OPG, RANK, and TLR4. The OPG/RANKL/RANK/TLR4 pathway is involved in SA-AKI pathogenesis. Recombinant RANKL treatment attenuates the inflammatory response and kidney tissue damage in SA-AKI, possibly via regulating this pathway. This pathway shows promise as a therapeutic target for SA-AKI.

Niu X ，Wang C ，Li H ，Chen W ... -  《BMC Nephrology》

TAK-242 improves sepsis-associated acute kidney injury in rats by inhibiting the TLR4/NF-κB signaling pathway.

Xia YM ，Guan YQ ，Liang JF ，Wu WD ... -  《-》

2,5-Dihydroxyacetophenone attenuates acute kidney injury induced by intra-abdominal infection in rats.

As one of the most serious complications of sepsis, acute kidney injury (AKI) is pathologically associated with excessive inflammation. 2,5-Dihydroxyacetophenone (DHAP) is isolated from Radix rehmanniae praeparata and exhibit potent anti-inflammatory property. This research aimed at determining the role of DHAP in sepsis-associated AKI (SA-AKI) and the underlying mechanism. Plasma creatinine (Cre), blood urea nitrogen (BUN), tumour necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) levels of SA-AKI patients were detected to evaluate their clinical characteristics. SA-AKI rat models were established by using caecum ligation puncture (CLP) surgery. CLP-induced rats were administered via oral gavage with 20 or 40 mg DHAP after 2 h of CLP surgery. Subsequently, survival rates, serum indexes, histopathological changes, inflammatory factors, renal function indexes and extracellular regulated protein kinases (ERK) and nuclear factor-κB (NF-κB) signalling pathways were detected. SA-AKI patients exhibited markedly higher levels of plasma Cre, BUN, TNF-α and IL-1β than healthy people. Compared with sham rats, CLP-induced septic rats showed significantly decreased survival rate, increased serum lactate dehydrogenase activity and serum lactate level, obvious renal histopathological injury, upregulated TNF-α, IL-1β and TGF-β1 levels, elevated serum creatinine, BUN and serum cystatin C concentrations, serum neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 levels and reduced renal artery blood flow. All the above CLP-induced changes in septic rats were mitigated after DHAP administration. Additionally, CLP-induced elevation in phosphorylated-ERK1/2 and nuclear NF-κB p65 protein levels was inhibited by DHAP treatment. DHAP hinders SA-AKI progression in rat models by inhibiting ERK and NF-κB signalling pathways.

Han T ，Jiang Y ，Ge W ，Lu Y ，Liu R ，Sun Z ... -  《-》

Neoastilbin ameliorates sepsis-induced liver and kidney injury by blocking the TLR4/NF-κB pathway.

Sepsis frequently causes systemic inflammatory response syndrome and multiple organ failure in patients. Neoastilbin (NAS) is a flavonoid that plays vital functions in inflammation. This work aims to investigate the protective effects of NAS against sepsis-induced liver and kidney injury and elucidate its underlying mechanisms. The mouse model was established using cecal ligation puncture (CLP) induction. NAS was given to mice by gavage for 7 consecutive days before surgery. Liver and kidney function, oxidative stress, and inflammatory factors in serum or tissues were examined by ELISA or related kits. The expression of relevant proteins was assessed by Western blot. Hematoxylin and eosin and/or periodic acid-Schiff staining revealed that NAS ameliorated the pathological damage in liver and kidney tissues of CLP-induced mice. NAS improved liver and kidney functions, as evidenced by elevated levels of blood urea nitrogen, Creatinine, ALT, and AST in the serum of septic mice. TUNEL assay and the expression of Bcl-2 and Bax showed that NAS dramatically reduced apoptosis in liver and renal tissues. NAS treatment lowered the levels of myeloperoxidase and malondialdehyde, while elevated the superoxide dismutase content in liver and kidney tissues of CLP-induced mice. The levels of inflammatory cytokines (IL-6, TNF-α, and IL-1β) in the serum and both tissues of CLP-injured mice were markedly decreased by NAS. Mechanically, NAS downregulated TLR4 expression and inhibited NF-κB activation, and overexpression of TLR4 reversed the protective effects of NAS against liver and kidney injury. Collectively, NAS attenuated CLP-induced apoptosis, oxidative stress, inflammation, and dysfunction in the liver and kidney by restraining the TLR4/NF-κB pathway.

Xu R ，Wang D ，Shao Z ，Li X ，Cao Q ... -  《-》

Expression of the RANK/RANKL/OPG system in the human intervertebral disc: implication for the pathogenesis of intervertebral disc degeneration.

Sano T ，Akeda K ，Yamada J ，Takegami N ，Sudo T ，Sudo A ... -  《BMC MUSCULOSKELETAL DISORDERS》