Cinnamtannin A2 protects the renal injury by attenuates the altered expression of kidney injury molecule 1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) expression in 5/6 nephrectomized rat model

Dihydromyricetin Nanoparticles Alleviate Lipopolysaccharide-Induced Acute Kidney Injury by Decreasing Inflammation and Cell Apoptosis via the TLR4/NF-κB Pathway

Acute kidney injury (AKI) is the most severe and fatal complication of sepsis resulting from infectious trauma. Currently, effective treatment options are still lacking. Dihydromyricetin is the main component extracted from Vine tea (Ampelopsis megalophylla Diels et Gilg). In our previous research, chitosan-tripolyphosphate-encapsulated nanoparticles of dihydromyricetin (CS-DMY-NPs) have been proven to have potential protective effects against cisplatin-induced AKI. Here, we investigated the protective effects and mechanisms of DMY and its nano-formulations against LPS-induced AKI by assessing pathological and inflammatory changes in mice. In mice with LPS-AKI treated with 300 mg/kg CS-DMY-NPs, the levels of creatinine (Cr), blood urea nitrogen (BUN), and KIM-1 were significantly reduced by 56%, 49%, and 88%, respectively. CS-DMY-NPs can upregulate the levels of GSH, SOD, and CAT by 47%, 7%, and 14%, respectively, to inhibit LPS-induced oxidative stress. Moreover, CS-DMY-NPs decreased the levels of IL-6, IL-1β, and MCP-1 by 31%, 49%, and 35%, respectively, to alleviate the inflammatory response. TUNEL and immunohistochemistry showed that CS-DMY-NPs reduced the number of apoptotic cells, increased the Bcl-2/Bax ratio by 30%, and attenuated renal cell apoptosis. Western blot analysis of renal tissue indicated that CS-DMY-NPs inhibited TLR4 expression and downregulated the phosphorylation of NF-κB p65 and IκBα. In summary, DMY prevented LPS-induced AKI by increasing antioxidant capacity, reducing inflammatory responses, and blocking apoptosis, and DMY nanoparticles were shown to have a better protective effect for future applications.

Insights into the Molecular Mechanisms of NRF2 in Kidney Injury and Diseases

Redox is a constant phenomenon in organisms. From the signaling pathway transduction to the oxidative stress during the inflammation and disease process, all are related to reduction-oxidation (redox). Nuclear factor erythroid 2-related factor 2 (NRF2) is a transcription factor targeting many antioxidant genes. In non-stressed conditions, NRF2 maintains the hemostasis of redox with housekeeping work. It expresses constitutively with basal activity, maintained by Kelch-like-ECH-associated protein 1 (KEAP1)-associated ubiquitination and degradation. When encountering stress, it can be up-regulated by several mechanisms to exert its anti-oxidative ability in diseases or inflammatory processes to protect tissues and organs from further damage. From acute kidney injury to chronic kidney diseases, such as diabetic nephropathy or glomerular disease, many results of studies have suggested that, as a master of regulating redox, NRF2 is a therapeutic option. It was not until the early termination of the clinical phase 3 trial of diabetic nephropathy due to heart failure as an unexpected side effect that we renewed our understanding of NRF2. NRF2 is not just a simple antioxidant capacity but has pleiotropic activities, harmful or helpful, depending on the conditions and backgrounds.

Quercetin improves contrast-induced acute kidney injury through the HIF-1α/lncRNA NEAT1/HMGB1 pathway

CONTEXT

The risk of contrast-induced acute kidney injury (CI-AKI) is increasing and the harm is great. Quercetin is the main active component in Abelmoschus manihot (L.) Medik (Malvaceae) and was reported to reduce the expression of HIF-1α.

OBJECTIVE

We investigate whether quercetin improves the CI-AKI through the HIF-1α/lncRNA NEAT1/HMGB1 pathway.

MATERIALS AND METHODS

HK-2 cells were treated with iohexol (200 mg/mL) for 6 h to establish a CI-AKI model. Quercetin (20 μM) was administered to CI-AKI cells cultured in dishes for 24 h. Cell morphology was observed by a fluorescence microscope. MTT and TUNEL assays were used to detect cell survival rate and apoptosis. Relative mRNA levels were measured by qRT-PCR. Protein levels were detected using western blotting. IL-6 and TNF-α protein levels were tested by Elisa assay. Targeting binding sites of HIF-1α and lncRNA NEAT1 were detected by luciferase assay.

RESULTS

The IC₅₀ value of quercetin was 163.25 μM. The expression levels of HIF-1α, lncRNA NEAT1 and HMGB1 were upregulated in the CI-AKI cell model. Quercetin diminished cell injury and apoptosis via inhibiting HIF-1α. Silencing of HIF-1α targeting lncRNA MEAT1 diminished cell injury and apoptosis. Silencing lncRNA NEAT1 has the same effect via suppressing HMGB1 expression. Collectively, quercetin diminished cell injury and apoptosis in CI-AKI cell model via the inhibition of HIF-1α on lncRNA NEAT1/HMGB1 signalling pathway.

DISCUSSION AND CONCLUSIONS

Quercetin diminished cell injury and apoptosis in CI-AKI cell mode via the inhibition of HIF-1α on the lncRNA NEAT1/HMGB1 signalling pathway, offering a potential novel therapeutic target for CI-AKI therapy.