Maresin 1 Attenuates Lipopolysaccharide-Induced Acute Kidney Injury via Inhibiting NOX4/ROS/NF-κB Pathway

Mitochondrial dysfunction in acute kidney injury

Acute kidney injury (AKI) is a systemic clinical syndrome increasing morbidity and mortality worldwide in recent years. Renal tubular epithelial cells (TECs) death caused by mitochondrial dysfunction is one of the pathogeneses. The imbalance of mitochondrial quality control is the main cause of mitochondrial dysfunction. Mitochondrial quality control plays a crucial role in AKI. Mitochondrial quality control mechanisms are involved in regulating mitochondrial integrity and function, including antioxidant defense, mitochondrial quality control, mitochondrial DNA (mtDNA) repair, mitochondrial dynamics, mitophagy, and mitochondrial biogenesis. Currently, many studies have used mitochondrial dysfunction as a targeted therapeutic strategy for AKI. Therefore, this review aims to present the latest research advancements on mitochondrial dysfunction in AKI, providing a valuable reference and theoretical foundation for clinical prevention and treatment of this condition, ultimately enhancing patient prognosis.

Protection of Ndrg2 deficiency on renal ischemia-reperfusion injury via activating PINK1/Parkin-mediated mitophagy

BACKGROUND

Renal ischemia-reperfusion (R-I/R) injury is the most prevalent cause of acute kidney injury, with high mortality and poor prognosis. However, the underlying pathological mechanisms are not yet fully understood. Therefore, this study aimed to investigate the role of N-myc downstream-regulated gene 2 ( Ndrg2 ) in R-I/R injury.

METHODS

We examined the expression of Ndrg2 in the kidney under normal physiological conditions and after R-I/R injury by immunofluorescence staining, real-time polymerase chain reaction, and western blotting. We then detected R-I/R injury in Ndrg2-deficient ( Ndrg2-/- ) mice and wild type ( Ndrg2+/+ ) littermates in vivo , and detected oxygen and glucose deprivation and reperfusion (OGD-R) injury in HK-2 cells. We further conducted transcriptomic sequencing to investigate the role of Ndrg2 in R-I/R injury and detected levels of oxidative stress and mitochondrial damage by dihydroethidium staining, biochemical assays, and western blot. Finally, we measured the levels of mitophagy in Ndrg2+/+ and Ndrg2-/- mice after R-I/R injury or HK-2 cells in OGD-R injury.

RESULTS

Ndrg2 was primarily expressed in renal proximal tubules and its expression was significantly decreased 24 h after R-I/R injury. Ndrg2-/- mice exhibited significantly attenuated R-I/R injury compared to Ndrg2+/+ mice. Transcriptomics profiling showed that Ndrg2 deficiency induced perturbations of multiple signaling pathways, downregulated inflammatory responses and oxidative stress, and increased autophagy following R-I/R injury. Further studies revealed that Ndrg2 deficiency reduced oxidative stress and mitochondrial damage. Notably, Ndrg2 deficiency significantly activated phosphatase and tensin homologue on chromosome ten-induced putative kinase 1 (PINK1)/Parkin-mediated mitophagy. The downregulation of NDRG2 expression significantly increased cell viability after OGD-R injury, increased the expression of heme oxygenase-1, decreased the expression of nicotinamide adenine dinucleotide phosphate oxidase 4, and increased the expression of the PINK1/Parkin pathway.

CONCLUSION

Ndrg2 deficiency might become a therapy target for R-I/R injury by decreasing oxidative stress, maintaining mitochondrial homeostasis, and activating PINK1/Parkin-mediated mitophagy.

Molecular mechanisms underlying methotrexate-induced intestinal injury and protective strategies

Methotrexate (MTX) is a folic acid reductase inhibitor that manages various malignancies as well as immune-mediated inflammatory chronic diseases. Despite being frequently prescribed, MTX's severe multiple toxicities can occasionally limit its therapeutic potential. Intestinal toxicity is a severe adverse effect associated with the administration of MTX, and patients are significantly burdened by MTX-provoked intestinal mucositis. However, the mechanism of such intestinal toxicity is not entirely understood, mechanistic studies demonstrated oxidative stress and inflammatory reactions as key factors that lead to the development of MTX-induced intestinal injury. Besides, MTX causes intestinal cells to express pro-inflammatory cytokines like interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), which activate nuclear factor-kappa B (NF-κB). This is followed by the activation of the Janus kinase/signal transducer and activator of the transcription3 (JAK/STAT3) signaling pathway. Moreover, because of its dual anti-inflammatory and antioxidative properties, nuclear factor erythroid-2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) has been considered a critical signaling pathway that counteracts oxidative stress in MTX-induced intestinal injury. Several agents have potential protective effects in counteracting MTX-provoked intestinal injury such as omega-3 polyunsaturated fatty acids, taurine, umbelliferone, vinpocetine, perindopril, rutin, hesperidin, lycopene, quercetin, apocynin, lactobacillus, berberine, zinc, and nifuroxazide. This review aims to summarize the potential redox molecular mechanisms of MTX-induced intestinal injury and how they can be alleviated. In conclusion, studying these molecular pathways might open the way for early alleviation of the intestinal damage and the development of various agent plans to attenuate MTX-mediated intestinal injury.

The dual role of lipids in chronic kidney disease: Pathogenic culprits and therapeutic allies

Chronic kidney disease (CKD) is a significant health burden, with rising incidence and prevalence, attributed in part to increasing obesity and diabetes rates. Lipid accumulation in the kidney parenchyma and chronic, low-grade inflammation are believed to significantly contribute to the development and progression of CKD. The effect of dysregulated kidney lipid metabolism in CKD progression, including altered cholesterol and fatty acid metabolism contribute to glomerular and tubular cell injury through the activation of oxidative stress and inflammatory signalling cascades. In contrast, classes of endogenous specialized pro-resolving lipid mediators (SPMs) have been described that act to limit the inflammatory response and promote the resolution of inflammation. This review highlights our current understanding of how lipids can cause damage within the kidney, and classes of protective lipid metabolites that offer therapeutic benefits.

Caveolin-1 ameliorates hepatic injury in non-alcoholic fatty liver disease by inhibiting ferroptosis via the NOX4/ROS/GPX4 pathway

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease globally, with a complex and contentious pathogenesis. Caveolin-1 (CAV1) is an important regulator of liver function and can mitigate liver injury by scavenging reactive oxygen species (ROS). Evidence suggests that NOX4 is a source of ROS production, that oxidative stress and ferroptosis are closely related, and that both are involved in the onset and progression of NAFLD. However, whether CAV1 attenuates liver injury in NAFLD caused by high-fat diet via the NOX4/ROS/GPX4 pathway remains unclear. An in vivo fatty liver model was established by feeding mice with a high-fat diet for 16 weeks. In addition, an in vitro fatty liver model was established by incubating AML-12 cells with free fatty acids for 24 h using an in vitro culture method. In our study, it was observed that a high-fat diet induces mitochondrial damage and worsens oxidative stress in NAFLD. This diet also hinders GPX4 expression, leading to an escalation of ferroptosis and lipid accumulation. To counteract these effects, intraperitoneal administration of CSD peptide in mice attenuated the high-fat diet-induced liver mitochondrial damage and ferroptosis. Likewise, overexpression of CAV1 resulted in an increase in GPX4 expression and a reduction in levels of ROS-mediated iron metamorphosis, thus mitigating the progression of the disease. However, the effects of CAV1 on GPX4-mediated ferroptosis and lipid deposition could be reversed by CAV1 small interfering RNA (SiRNA). Finally, NOX4 inhibitor (GLX351322) treatment increased CAV1 siRNA-mediated GPX4 expression and decreased the level of ROS-mediated ferroptosis. These findings suggest a potential mechanism underlying the protective role of CAV1 against high-fat diet-induced hepatotoxicity in NAFLD, shedding new light on the interplay between CAV1, GPX4, and ferroptosis in liver pathology.

Nox4 is involved in acute kidney injury associated to intravascular hemolysis

Massive intravascular hemolysis occurs not unfrequently in many clinical conditions. Breakdown of erythrocytes promotes the accumulation of heme-derivates in the kidney, increasing oxidative stress and cell death, thus promoting acute kidney injury (AKI). NADPH oxidase 4 (Nox4) is a major source of reactive oxygen species (ROS) in the kidney, however it is unknown the role of Nox4 in hemolysis and whether inhibition of this enzyme may protect from heme-mediated injury. To answer these questions, we elicited intravascular hemolysis in wild type and Nox4 knockout mice. We also evaluated whether nephrotoxic effects of heme may be reduced by using Nox4 siRNA and pharmacologic inhibition with GKT137831, a Nox4 inhibitor, both in vivo and in cultured renal cells. Our results showed that induction of massive hemolysis elicited AKI characterized by loss of renal function, morphological alterations of the tubular epithelium and podocytes, oxidative stress, inflammation, mitochondrial dysfunction, blockade of autophagy and cell death. These pathological effects were significantly prevented in Nox4-deficient mice and in animals treated with GKT137831. In vitro studies showed that Nox4 disruption by specific siRNAs or Nox4 inhibitors declined heme-mediated ROS production and cell death. Our data identify Nox4 as a key enzyme involved in intravascular hemolysis-induced AKI. Thus, Nox4 inhibition may be a potential therapeutic approach to prevent renal damage in patients with severe hemolytic crisis.

Protective effect of long-chain polyunsaturated fatty acids on hepatorenal syndrome in rats

BACKGROUND

Hepatorenal syndrome (HRS) is the most prevalent form of acute kidney injury in cirrhotic patients. It is characterized by reduced renal blood flow and represents the most severe complication in cirrhotic patients with advanced disease. Previous research has indicated that antioxidants can delay the onset of a hyperdynamic circulatory state in cirrhosis and improve renal function in HRS patients. Regular omega-3 supplementation has significantly reduced the risk of liver disease. This supplementation could represent an additional therapy for individuals with HRS.

AIM

To evaluated the antioxidant effect of omega-3 polyunsaturated fatty acid supplementation on the kidneys of cirrhotic rats.

METHODS

Secondary biliary cirrhosis was induced in rats by biliary duct ligation (BDL) for 28 d. We used 24 male Wistar rats divided into the following groups: I (control); II (treated with omega-3, 1 g/kg of body weight); III (BDL treated with omega-3, 1 g/kg of body weight); and IV (BDL without treatment). The animals were killed by overdose of anesthetic; the kidneys were dissected, removed, frozen in liquid nitrogen, and stored in a freezer at -80℃ for later analysis. We evaluated oxidative stress, nitric oxide (NO) metabolites, DNA damage by the comet assay, cell viability test, and apoptosis in the kidneys. Data were analyzed by one-way analysis of variance, and means were compared using the Tukey test, with P ≤ 0.05.

RESULTS

Omega-3 significantly decreased the production of reactive oxygen species (P < 0.001) and lipoperoxidation in the kidneys of cirrhotic rats treated with omega-3 (P < 0.001). The activity of the antioxidant enzymes superoxide dismutase and catalase increased in the BDL+omega-3 group compared to the BDL group (P < 0.01). NO production, DNA damage, and caspase-9 cleavage decreased significantly in the omega-3-treated BDL group. There was an increase in mitochondrial electrochemical potential (P < 0.001) in BDL treated with omega-3 compared to BDL. No changes in the cell survival index in HRS with omega-3 compared to the control group (P > 0.05) were observed.

CONCLUSION

The study demonstrates that omega-3 can protect cellular integrity and function by increasing antioxidant enzymes, inhibiting the formation of free radicals, and reducing apoptosis.

Pharmacological effects of specialized pro-resolving mediators in sepsis-induced organ dysfunction: a narrative review

Sepsis is a life-threatening syndrome of organ dysfunction, characterized by uncontrolled inflammatory response and immune dysregulation, often leading to multiple organ failure and even death. Specialized pro-resolving mediators (SPMs), which are typically thought to be formed via consecutive steps of oxidation of polyenoic fatty acids, have been shown to suppress inflammation and promote timely resolution of inflammation. They are mainly divided into four categories: lipoxins, resolvins, protectins, and maresins. The SPMs may improve the prognosis of sepsis by modulating the immune and inflammatory balance, thereby holding promise for clinical applications. However, their biosynthetic and pharmacological properties are very complex. Through a literature review, we aim to comprehensively elucidate the protective mechanisms of different SPMs in sepsis and its organ damage, in order to provide sufficient theoretical basis for the future clinical translation of SPMs.

Metabolic reprogramming in septic acute kidney injury: pathogenesis and therapeutic implications

Acute kidney injury (AKI) is a frequent and severe complication of sepsis and is characterized by significant mortality and morbidity. However, the pathogenesis of septic acute kidney injury (S-AKI) remains elusive. Metabolic reprogramming, which was originally referred to as the Warburg effect in cancer, is strongly related to S-AKI. At the onset of sepsis, both inflammatory cells and renal parenchymal cells, such as macrophages, neutrophils and renal tubular epithelial cells, undergo metabolic shifts toward aerobic glycolysis to amplify proinflammatory responses and fortify cellular resilience to septic stimuli. As the disease progresses, these cells revert to oxidative phosphorylation, thus promoting anti-inflammatory reactions and enhancing functional restoration. Alterations in mitochondrial dynamics and metabolic reprogramming are central to the energetic changes that occur during S-AKI. In this review, we summarize the current understanding of the pathogenesis of metabolic reprogramming in S-AKI, with a focus on each cell type involved. By identifying relevant key regulatory factors, we also explored potential metabolic reprogramming-related therapeutic targets for the management of S-AKI.

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.

Rehmapicrogenin attenuates lipopolysaccharide-induced podocyte injury and kidney dysfunctions by regulating nuclear factor E2-related factor 2/antioxidant response element signalling

BACKGROUND

Apoptosis and oxidative stress in kidneys are critical players in acute kidney injury (AKI). Rehmapicrogenin, a monomeric compound extracted from Rehmanniae radix, has been found to possess nitric oxide inhibitory and anti-inflammatory activities. Thus, this study aimed to investigate the roles and mechanisms of rehmapicrogenin in AKI.

METHODS

Lipopolysaccharide (LPS) was used to induce AKI-like conditions. Cell survival conditions were detected by cell counting kit-8 assays and flow cytometry. Several renal function markers including blood urea nitrogen, proteinuria, creatinine, and albumin were measured. Apoptosis and reactive oxygen species (ROS) production were examined by TUNEL and dihydroethidium staining, respectively. Haematoxylin-eosin staining and periodic acid-Schiff staining were conducted to assess histopathological changes. Gene expression was evaluated by western blotting, commercially available kits and immunofluorescence staining.

RESULTS

For in vitro analysis, rehmapicrogenin inhibited the LPS-induced podocyte apoptosis by activating the Nrf2/ARE pathway. For in vivo analysis, rehmapicrogenin improved renal functions in LPS-induced mice. Additionally, rehmapicrogenin suppressed LPS-induced podocyte apoptosis and oxidative stress in kidney tissues. Mechanistically, rehmapicrogenin activated the Nrf2/ARE pathway in LPS-induced mice.

CONCLUSION

Rehmapicrogenin relieves the podocyte injury and renal dysfunctions through activating the Nrf2/ARE pathway to inhibit apoptosis and oxidative stress.

SKLB023 protects against inflammation and apoptosis in sepsis-associated acute kidney injury via the inhibition of toll-like receptor 4 signaling

Sepsis-associated acute kidney injury (SA-AKI) is one of common critical illnesses with high morbidity and mortality. At present, effective therapeutic drugs for SA-AKI are remain lacking. SKLB023 is a synthetic small-molecule compound which exerts potent anti-inflammatory effects in our previous studies. Here, this study aimed to characterize the protective effect of SKLB023 on SA-AKI and explore its underlying mechanism. The SA-AKI experimental models have been established by cecum ligation/puncture (CLP) and lipopolysaccharide (LPS) injection in male C57BL/6J mice. SKLB023 was administered by gavage (50 or 25 mg/kg in CLP model and 50 mg/kg in LPS model) daily 3 days in advance and 30 min earlier on the day of modeling. Our results confirmed SKLB023 treatment could improve the survival of SA-AKI mice and ameliorate renal pathological injury, inflammation, and apoptosis in the two types of septic AKI mice. Mechanically, SKLB023 deceased the expression of TLR4 in LPS-triggered renal tubular epithelial cells, and inhibited the activation of downstream pathways including NF-κB and MAPK pathways. Our study suggested that SKLB023 is expected to be a potential drug for the prevention and treatment of septic AKI.

Proteomics coupled transcriptomics reveals Slc34a1 and Slc34a3 downregulation as potential features of nephrotoxin-induced acute kidney injury

Acute kidney injury (AKI) stands as a prevalent and economically burdensome condition worldwide, yet its complex molecular mechanisms remain incompletely understood. To address this gap, our study employs a multifaceted approach, combining mass spectrometry and RNA sequencing technologies, to elucidate the intricate molecular landscape underlying nephrotoxin-induced AKI in mice by cisplatin- and LPS-induced. By examining the protein and RNA expression profiles, we aimed to uncover novel insights into the pathogenesis of AKI and identify potential diagnostic and therapeutic targets. Our results demonstrate significant down-regulation of Slc34a1 and Slc34a3, shedding light on their crucial roles in AKI pathology and highlighting their promise as actionable targets for diagnosis and treatment. This comprehensive analysis not only enhances our understanding of AKI pathophysiology but also offers valuable avenues for the development of targeted interventions to mitigate its clinical impact. SIGNIFICANCE: Nephrotoxicity acute kidney injury (AKI) is a common clinical condition whose pathogenesis is the process by which some drugs, chemicals or other factors cause damage to the kidneys, resulting in impaired kidney function. Although it has been proved that different nephrotoxic substances can affect the kidney through different pathways, whether they have a commonality has not been registered. Here, we combined transcriptomics and proteomics to study the molecular mechanism of LPS and cisplatin-induced nephrotoxic acute kidney injury finding that the down-regulation of Slc34a1 and Slc34a3 may be a critical link in nephrotoxic acute kidney injury, which can be used as a marker for its early diagnosis.

The Dysregulation of Essential Fatty Acid (EFA) Metabolism May Be a Factor in the Pathogenesis of Sepsis

I propose that a deficiency of essential fatty acids (EFAs) and an alteration in their (EFAs) metabolism could be a major factor in the pathogenesis of sepsis and sepsis-related mortality. The failure of corticosteroids, anti-TNF-α, and anti-interleukin-6 monoclonal antibodies can be attributed to this altered EFA metabolism in sepsis. Vitamin C; folic acid; and vitamin B1, B6, and B12 serve as co-factors necessary for the activity of desaturase enzymes that are the rate-limiting steps in the metabolism of EFAs. The altered metabolism of EFAs results in an imbalance in the production and activities of pro- and anti-inflammatory eicosanoids and cytokines resulting in both hyperimmune and hypoimmune responses seen in sepsis. This implies that restoring the metabolism of EFAs to normal may form a newer therapeutic approach both in the prevention and management of sepsis and other critical illnesses.

The role of mitochondrial dysfunction in kidney injury and disease

Mitochondria are the main sites of aerobic respiration in the cell and mainly provide energy for the organism, and play key roles in adenosine triphosphate (ATP) synthesis, metabolic regulation, and cell differentiation and death. Mitochondrial dysfunction has been identified as a contributing factor to a variety of diseases. The kidney is rich in mitochondria to meet energy needs, and stable mitochondrial structure and function are essential for normal kidney function. Recently, many studies have shown a link between mitochondrial dysfunction and kidney disease, maintaining mitochondrial homeostasis has become an important target for kidney therapy. In this review, we integrate the role of mitochondrial dysfunction in different kidney diseases, and specifically elaborate the mechanism of mitochondrial reactive oxygen species (mtROS), autophagy and ferroptosis involved in the occurrence and development of kidney diseases, providing insights for improved treatment of kidney diseases.

Maresins as novel anti-inflammatory actors and putative therapeutic targets in sepsis

Sepsis, a complex clinical syndrome characterized by an exaggerated host response to infection, often necessitates hospitalization and intensive care unit admission. Delayed or inaccurate diagnosis of sepsis, coupled with suboptimal treatment strategies, can result in unfavorable outcomes, including mortality. Maresins, a newly discovered family of lipid mediators synthesized from docosahexaenoic acid by macrophages, have emerged as key players in promoting inflammation resolution and the termination of inflammatory processes. Extensive evidence has unequivocally demonstrated the beneficial effects of maresins in modulating the inflammatory response associated with sepsis; however, their bioactivity and functions exhibit remarkable diversity and complexity. This article presents a comprehensive review of recent research on the role of maresins in sepsis, aiming to enhance our understanding of their effectiveness and elucidate the specific mechanisms underlying their actions in sepsis treatment. Furthermore, emerging insights into the management of patients with sepsis are also highlighted.

Systemic inflammation response index as a prognostic factor for patients with sepsis-associated acute kidney injury: a retrospective observational study

OBJECTIVE

To assess the association between the systemic inflammation response index (SIRI) and the prognosis in patients with sepsis-associated acute kidney injury (SA-AKI).

METHODS

In this observational study, adult patients with SA-AKI were categorized into three groups based on SIRI tertiles. Survival outcomes were compared across the three groups using Kaplan-Meier survival curves. Various Cox proportional hazards regression models were developed to determine the association between the SIRI and mortality in patients with SA-AKI. Subgroup analyses were also performed to explore the association between different SIRI tertiles and all-cause mortality.

RESULTS

After adjusting for several confounders, the second SIRI tertile (2.5 < SIRI < 7.6) was found to be an independent risk factor for 30-day mortality [hazard ratio (95% confidence interval): 1.19 (1.01-1.40)], 90-day mortality [1.22 (1.06-1.41)], and 365-day mortality [1.24 (1.09-1.40)]. Furthermore, high SIRI values were associated with increased risks of 30-day, 90-day, and 365-day mortality in patients with SA-AKI across all three models. The third tertile showed a significant association with adverse outcomes in most subgroups.

CONCLUSIONS

The SIRI serves as a comprehensive biomarker for predicting all-cause mortality of critically ill patients with SA-AKI.

Aging-related NOX4-Nrf2 redox imbalance increases susceptibility to cisplatin-induced acute kidney injury by regulating mitophagy

BACKGROUND

During aging, excessive ROS production in the kidneys leads to redox imbalance, which contributes to oxidative damage and impaired organ homeostasis. However, whether and how aging-related NOX4-Nrf2 redox imbalance increases susceptibility to cisplatin-induced acute kidney injury remain largely unknown.

METHODS

In this study, we used cisplatin-challenged aging mouse models and senescent HK-2 cells to investigate the effects and mechanisms of aging on susceptibility to cisplatin-induced acute kidney injury.

RESULTS

In vivo, we found that cisplatin stimulation caused more severe renal damage, oxidative stress, mitochondrial dysfunction and mitophagy impairment in aging mice than in young mice. Moreover, Nrf2 deficiency aggravated cisplatin-induced acute kidney injury by exacerbating NOX4-Nrf2 redox imbalance and defective mitophagy. In vitro experiments on D-gal-treated human renal tubular epithelial cells (HK-2) demonstrated that senescent renal epithelial cells exhibited increased susceptibility to cisplatin-induced apoptosis, NOX4-Nrf2 redox imbalance-mediated oxidative stress and defective mitophagy. Mechanistically, we found that knockdown of Nrf2 in HK2 cells resulted in increased ROS and aggravated mitophagy impairment, whereas these effects were reversed in NOX4-knockdown cells.

CONCLUSION

The present study indicates that NOX4-Nrf2 redox imbalance is critical for mitophagy deficiency in aged renal tubular epithelial cells and is a therapeutic target for alleviating cisplatin-induced acute kidney injury in elderly patients.

Folic acid antioxidant supplementation to binge drinking adolescent rats improves hydric-saline balance and blood pressure, but fails to increase renal NO availability and glomerular filtration rate

Binge drinking (BD) is an especially pro-oxidant pattern of alcohol consumption, particularly widespread in the adolescent population. In the kidneys, it affects the glomerular filtration rate (GFR), leading to high blood pressure. BD exposure also disrupts folic acid (FA) homeostasis and its antioxidant properties. The aim of this study is to test a FA supplementation as an effective therapy against the oxidative, nitrosative, and apoptotic damage as well as the renal function alteration occurred after BD in adolescence. Four groups of adolescent rats were used: control, BD (exposed to intraperitoneal alcohol), control FA-supplemented group and BD FA-supplemented group. Dietary FA content in control groups was 2 ppm, and 8 ppm in supplemented groups. BD provoked an oxidative imbalance in the kidneys by dysregulating antioxidant enzymes and increasing the enzyme NADPH oxidase 4 (NOX4), which led to an increase in caspase-9. BD also altered the renal nitrosative status affecting the expression of the three nitric oxide (NO) synthase (NOS) isoforms, leading to a decrease in NO levels. Functionally, BD produced a hydric-electrolytic imbalance, a low GFR and an increase in blood pressure. FA supplementation to BD adolescent rats improved the oxidative, nitrosative, and apoptotic balance, recovering the hydric-electrolytic equilibrium and blood pressure. However, neither NO levels nor GFR were recovered, showing in this study for the first time that NO availability in the kidneys plays a crucial role in GFR regulation that the antioxidant effects of FA cannot repair.

Chronic cadmium exposure triggered ferroptosis by perturbing the STEAP3-mediated glutathione redox balance linked to altered metabolomic signatures in humans

Cadmium (Cd), a predominant environmental pollutant, is a canonical toxicant that acts on the kidneys. However, the nephrotoxic effect and underlying mechanism activated by chronic exposure to Cd remain unclear. In the present study, male mice (C57BL/6J, 8 weeks) were treated with 0.6 mg/L cadmium chloride (CdCl2) administered orally for 6 months, and tubular epithelial cells (TCMK-1 cells) were treated with low-dose (1, 2, and 3 μM) CdCl2 for 72 h (h). Our study results revealed that environmental Cd exposure triggered ferroptosis and renal dysfunction. Spatially resolved metabolomics enabled delineation of metabolic profiles and visualization of the disruption to glutathione homeostasis related to ferroptosis in mouse kidneys. Multiomics analysis revealed that chronic Cd exposure induced glutathione redox imbalance that depended on STEAP3-driven lysosomal iron overload. In particular, glutathione metabolic reprogramming linked to ferroptosis emerged as a metabolic hallmark in the blood of Cd-exposed workers. In conclusion, this study provides the first evidence indicating that chronic Cd exposure triggers ferroptosis and renal dysfunction that depend on STEAP3-mediated glutathione redox imbalance, greatly increasing our understanding of the metabolic reprogramming induced by Cd exposure in the kidneys and providing novel clues linking chronic Cd exposure to nephrotoxicity.

Maresin1 ameliorates MSU crystal-induced inflammation by upregulating Prdx5 expression

BACKGROUND

Maresin1 (MaR1) is a potent lipid mediator that exhibits significant anti-inflammatory activity in the context of several inflammatory diseases. A previous study reported that MaR1 could suppress MSU crystal-induced peritonitis in mice. To date, the molecular mechanism by which MaR1 inhibits MSU crystal-induced inflammation remains poorly understood.

METHODS

Mousebone marrow-derived macrophages (BMDMs) were pretreated with MaR1 and then stimulated with FAs (palmitic, C16:0 and stearic, C18:0) plus MSU crystals (FAs + MSUc). In vivo, the effects of MaR1 treatment or Prdx5 deficiency on MSUc induced peritonitis and arthritis mouse models were evaluated.

RESULTS

The current study indicated that MaR1 effectively suppressed MSUc induced inflammation in vitro and in vivo. MaR1 reversed the decrease in Prdx5 mRNA and protein levels induced by FAs + MSUc. Further assays demonstrated that MaR1 acceleratedPrdx5 expression by regulating the Keap1-Nrf2 signaling axis. Activation of AMPK by Prdx5 improved homeostasis of the TXNIP and TRX proteins and alleviated mitochondrial fragmentation. In addition, Prdx5 overexpression inhibited the expression of CPT1A, a key enzyme for fatty acid oxidation (FAO). Prdx5 protected against defects in FA + MSUc induced FAO and the urea cycle.

CONCLUSION

MaR1 treatment effectively attenuated MSUc induced inflammation by upregulating Prdx5 expression. Our study provides a new strategy by which Prdx5 may help prevent acute gout attacks.

Compound 5 alleviated acute kidney injury without affecting the antitumor effect after cisplatin treatment

Despite being a powerful weapon against cancer cells, cisplatin's therapeutic potential is hampered by numerous adverse reactions, including acute kidney injury (AKI). Compound 5 has 3-SH fragments at the end of the vertical short alkyl side chain, which is an ROS scavenger synthesized. In this study, we evaluated the protective effect of compound 5 on the kidney after cisplatin administration and its mechanism. The results founded that compound 5 can alleviate serum urea nitrogen and serum creatinine induced by cisplatin administration in vivo. In addition, histopathological analysis of the kidneys showed that compound 5 significantly reduced cisplatin-induced (Cis-induced) renal toxicity compared with the cisplatin group. A mechanism study showed that compound 5 significantly reduces NOX4 levels, improves the activity of antioxidant enzymes (SOD and GSH-Px), reduces Malondialdehyde (MDA) levels, increases the total antioxidant level, reduces oxidative stress, and thus reduces kidney tissue damage. At the same time, compound 5 activated the Nrf2 signaling pathway. In addition, it can increase the expression of Bax, reduce the expression of Bcl-2 and caspase-3, a marker of apoptosis, which is beneficial to the survival of kidney cells. Additionally, compound 5 did not interfere with the antitumor effects of cisplatin in in vivo xenotransplantation models.

Vaccarin alleviates cisplatin-induced acute kidney injury via decreasing NOX4-derived ROS

Cisplatin is a chemotherapeutant widely used in treating solid tumors, with the common side effect of acute kidney injury (AKI). Developing effective useful agent for preventing or treating cisplatin-induced AKI is of great importance. In this study, we investigate the protective effect of vaccarin, a chemical entity of flavonoid glycoside, against cisplatin-induced AKI. Cisplatin-treated C57BL/6J mice and human kidney-2 (HK-2) cells were used as the model of cisplatin-induced AKI. The levels of blood urea nitrogen (BUN) and creatine (Cr) levels and periodic acid-Schiff staining (PAS) scores decreased when vaccarin was administrated. Vaccarin had no impact on renal platinum accumulation, which was detected by the ICP-MS 6 h after cisplatin injection. Moreover, vaccarin can significantly alleviate the product of reactive oxygen species and the expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (NOX4) in cisplatin-induced AKI, both in vivo and in vitro. In addition, vaccarin decreased the receptor-interacting protein kinase 1 (RIPK1) related programmed necrosis (necroptosis), cell apoptosis (shown by the protein levels of cleaved-caspase3 and flow cytometry) and inflammation (shown by the decreased levels of NLRP3, p-P65 and the mRNA of several inflammatory factors). NOX4 inhibitor GLX351322 (GLX) and NOX4 kowndown by siRNA have equivalent protective effect of vaccarin in vitro. When vaccarin was administered together with GLX or NOX4 siRNA, this protective effect of vaccarin did not further increase, as indicating by the index of oxidative stress, cell viability, necroptosis and apoptosis. In conclusion, vaccarin can alleviate cisplatin-induced AKI via inhibiting NOX4.

Maresin1 prevents sepsis-induced acute liver injury by suppressing NF-κB/Stat3/MAPK pathways, mitigating inflammation

Aims

The treatment of sepsis remains challenging and the liver is a non-neglectful target of sepsis-induced injury. Uncontrolled inflammatory responses exert a central role in the pathophysiological process of sepsis-induced acute liver injury (SI-ALI). Maresin1 (MaR1) is a derivative of omega-3 docosahexaenoic acid (DHA), which has been shown to have anti-inflammatory effects and is effective in a variety of sepsis-related diseases. This study aimed to determine the effect of MaR1 on cecal ligation and puncture (CLP)-caused SI-ALI and explore its possible mechanisms.

Main methods

Mice were subjected to CLP, and then intravenously injected via tail vein with low-dose MaR1 (0.5 ng, 200 μL) or high-dose MaR1 (1 ng, 200 μL) or sterile normal saline (NS) (200 μL) 1 h later. Then, the survival rate, body weight change, liver function, bacterial load, neutrophil infiltration, and inflammatory cytokines were detected.

Results

MaR1 significantly increased the 7-day survival rate and reduced the bacterial load in peritoneal lavage fluid and blood in a dose-dependent manner in mice with SI-ALI. Treatment with MaR1 could also restore the function of the liver in septic mice. Besides, MaR1 exerted anti-inflammatory effects by decreasing the expression of pro-inflammatory molecules (TNF-α, IL-6 and IL-1β), bacterial load, and neutrophil infiltration and increasing the expression of anti-inflammatory molecules (IL-10).

Significance

Our experimental results showed that MaR1 alleviated liver injury induced by sepsis. This work highlighted a potential clinic use of MaR1 in treating acute inflammation of SI-ALI, but also provided new insight into the underlying molecular mechanism.

Plasma oxidative lipidomics reveals signatures for sepsis-associated acute kidney injury

BACKGROUND

Oxidized lipids are essential bioactive lipid mediators generated during infection that regulate oxidative stress and the inflammatory response, but their signatures in patients with sepsis-associated acute kidney injury (SA-AKI) are poorly understood. This study analyzed the oxidative lipidomics of plasma from patients with SA-AKI to reveal the underlying biomarkers and pathophysiological mechanisms involved in sepsis.

MATERIALS

A total of 67 patients with SA-AKI and 20 age- and sex-matched healthy controls (HCs) participated in this prospective cohort study. Among the patients with SA-AKI, 14 cases had stage I-II AKI and 53 cases had stage III AKI. Oxidative lipidomic analysis of plasma samples was conducted using ultra performance liquid chromatography coupled with tandem mass spectrometric (UPLC-MS /MS) detection.

RESULTS

Among 21 kinds of differentially oxidized lipids, 5(S),12(S)-DiHETE, 5-isoPGF2VI, 5,6-DiHETrE, 11,12-EET and 9,10-DiHOME showed the best performance. The prediction model incorporating them has shown highly sensitive and specific in distinguishing different stages of SA-AKI from HCs. The annotation of Kyoto Encyclopedia of Genes and Genomes illustrated that the overall downregulation of vascular smooth muscle contraction was closely related to the pathophysiological mechanism of SA-AKI.

CONCLUSION

This study revealed alterations in the characteristic oxidized lipids in the plasma of SA-AKI patients, and these lipids had high diagnostic efficiency and potential targeted intervention value for SA-AKI.

Sirtuin1 Mediates the Protective Effects of Echinacoside against Sepsis-Induced Acute Lung Injury via Regulating the NOX4-Nrf2 Axis

Currently, the treatment for sepsis-induced acute lung injury mainly involves mechanical ventilation with limited use of drugs, highlighting the urgent need for new therapeutic options. As a pivotal aspect of acute lung injury, the pathologic activation and apoptosis of endothelial cells related to oxidative stress play a crucial role in disease progression, with NOX4 and Nrf2 being important targets in regulating ROS production and clearance. Echinacoside, extracted from the traditional Chinese herbal plant Cistanche deserticola, possesses diverse biological activities. However, its role in sepsis-induced acute lung injury remains unexplored. Moreover, although some studies have demonstrated the regulation of NOX4 expression by SIRT1, the specific mechanisms are yet to be elucidated. Therefore, this study aimed to investigate the effects of echinacoside on sepsis-induced acute lung injury and oxidative stress in mice and to explore the intricate regulatory mechanism of SIRT1 on NOX4. We found that echinacoside inhibited sepsis-induced acute lung injury and oxidative stress while preserving endothelial function. In vitro experiments demonstrated that echinacoside activated SIRT1 and promoted its expression. The activated SIRT1 was competitively bound to p22 phox, inhibiting the activation of NOX4 and facilitating the ubiquitination and degradation of NOX4. Additionally, SIRT1 deacetylated Nrf2, promoting the downstream expression of antioxidant enzymes, thus enhancing the NOX4-Nrf2 axis and mitigating oxidative stress-induced endothelial cell pathologic activation and mitochondrial pathway apoptosis. The SIRT1-mediated anti-inflammatory and antioxidant effects of echinacoside were validated in vivo. Consequently, the SIRT1-regulated NOX4-Nrf2 axis may represent a crucial target for echinacoside in the treatment of sepsis-induced acute lung injury.

Omega-3 Lipid Mediators: Modulation of the M1/M2 Macrophage Phenotype and Its Protective Role in Chronic Liver Diseases

The complex interplay between dietary factors, inflammation, and macrophage polarization is pivotal in the pathogenesis and progression of chronic liver diseases (CLDs). Omega-3 fatty acids (FAs) have brought in attention due to their potential to modulate inflammation and exert protective effects in various pathological conditions. Omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have shown promise in mitigating inflammation and enhancing the resolution of inflammatory responses. They influence the M1/M2 macrophage phenotype balance, promoting a shift towards the M2 anti-inflammatory phenotype. Specialized pro-resolving mediators (SPMs), such as resolvins (Rvs), protectins (PDs), and maresins (MaRs), have emerged as potent regulators of inflammation and macrophage polarization. They show anti-inflammatory and pro-resolving properties, by modulating the expression of cytokines, facilitate the phagocytosis of apoptotic cells, and promote tissue repair. MaR1, in particular, has demonstrated significant hepatoprotective effects by promoting M2 macrophage polarization, reducing oxidative stress, and inhibiting key inflammatory pathways such as NF-κB. In the context of CLDs, such as nonalcoholic fatty liver disease (NAFLD) and cirrhosis, omega-3s and their SPMs have shown promise in attenuating liver injury, promoting tissue regeneration, and modulating macrophage phenotypes. The aim of this article was to analyze the emerging role of omega-3 FAs and their SPMs in the context of macrophage polarization, with special interest in the mechanisms underlying their effects and their interactions with other cell types within the liver microenvironment, focused on CLDs and the development of novel therapeutic strategies.

CircRNA itchy E3 ubiquitin protein ligase improves mitochondrial dysfunction in sepsis-induced acute kidney injury by targeting microRNA-214-3p/ATP-binding cassette A1 axis

BACKGROUND

Circular RNAs (circRNAs) are promising biomarkers and therapeutic targets for acute kidney injury (AKI). In this study, we investigated the mechanism by which circRNA itchy E3 ubiquitin protein ligase (circ-ITCH) regulates sepsis-induced AKI.

METHODS

A sepsis-induced AKI mouse model was created using LPS induction and circ-ITCH overexpression. Circ-ITCH levels were confirmed via RT-qPCR. Kidney tissue changes were examined through various stains and TUNEL. Enzyme-linked immunosorbent assay (ELISA) gauged oxidative stress and inflammation. Mitochondrial features were studied with electron microscopy. RT-qPCR and western blotting assessed mitochondrial function parameters. Using starBase, binding sites between circ-ITCH and miR-214-3p, as well as miR-214-3p and ABCA1, were predicted. Regulatory connections were proven by dual-luciferase assay, RT-qPCR, and western blotting.

RESULTS

Circ-ITCH expression was downregulated in LPS-induced sepsis mice. Overexpression of circ-ITCH ameliorates indicators of renal function (serum creatinine [SCr], blood urea nitrogen [BUN], neutrophil gelatinase-associated lipocalin [NGAL], and kidney injury molecule-1 [Kim-1]), reduces renal cell apoptosis, mitigates oxidative stress markers (reactive oxygen species [ROS] and malondialdehyde [MDA]), and diminishes inflammatory markers (interleukin [IL]-1β, IL-6, and tumor necrosis factor [TNF-α]). Moreover, circ-ITCH overexpression alleviated mitochondrial damage and dysfunction. Furthermore, circ-ITCH acts as a sponge for miR-214-3p, thereby upregulating ABCA1 expression. In addition, the miR-214-3p inhibitor repressed oxidative stress, inflammation, and mitochondrial dysfunction, which was reversed by circ-ITCH knockdown. Further cellular analysis in HK-2 cells supported these findings, highlighting the protective role of circ-ITCH against sepsis-induced AKI, particularly through the miR-214-3p/ABCA1 axis.

CONCLUSION

The novel circ-ITCH/miR-214-3p/ABCA1 pathway plays an essential role in the regulation of oxidative stress and mitochondrial dysfunction in sepsis-induced AKI.

Maresin-1 inhibits high glucose induced ferroptosis in ARPE-19 cells by activating the Nrf2/HO-1/GPX4 pathway

BACKGROUND

Maresin-1 plays an important role in diabetic illnesses and ferroptosis is associated with pathogenic processes of diabetic retinopathy (DR). The goal of this study is to explore the influence of maresin-1 on ferroptosis and its molecular mechanism in DR.

METHODS

ARPE-19 cells were exposed to high glucose (HG) condition for developing a cellular model of DR. The CCK-8 assay and flow cytometry were used to assess ARPE-19 cell proliferation and apoptosis, respectively. Furthermore, the GSH content, MDA content, ROS level, and Fe2+ level were measured by using a colorimetric GSH test kit, a Lipid Peroxidation MDA Assay Kit, a DCFH-DA assay and the phirozine technique, respectively. Immunofluorescence labelling was used to detect protein levels of ACSL4 and PTGS2. Messenger RNA and protein expression of HO-1, GPX4 and Nrf2 was evaluated through western blotting and quantitative real time-polymerase chain reaction (qRT-PCR). To establish a diabetic mouse model, mice were intraperitoneally injected 150 mg/kg streptozotocin. The MDA content, ROS level and the iron level were detected by using corresponding commercial kits.

RESULTS

Maresin-1 promoted cell proliferation while reducing the apoptotic process in HG-induced ARPE-19 cells. Maresin-1 significantly reduced ferroptosis induced by HG in ARPE-19 cells, as demonstrated as a result of decreased MDA content, ROS level, Fe2+ level, PTGS2 expression, ACSL4 expression and increased GSH content. With respect to mechanisms, maresin-1 treatment up-regulated the mRNA expression and protein expression of HO-1, GPX4 and Nrf2 in HG-induced ARPE-19 cells. Nrf2 inhibitor reversed the inhibitory effects of maresin-1 on ferroptosis in HG-induced ARPE-19 cells. In vivo experiments, we found that Maresin-1 evidently repressed ferroptosis a mouse model of DR, as evidenced by the decreased MDA content, ROS level and iron level in retinal tissues of mice.

CONCLUSION

Maresin-1 protects ARPE cells from HG-induced ferroptosis via activating the Nrf2/HO-1/GPX4 pathway, suggesting that maresin-1 prevents DR development.

Deubiquitinase BAP1 regulates stability of BRCA1 protein and inactivates the NF-κB signaling to protect mice from sepsis-induced acute kidney injury

Sepsis and its associated organ dysfunction syndrome is a leading cause of death in critically ill patients. Breast cancer susceptibility protein 1 (BRCA1)-associated protein 1 (BAP1) is a potential regulator in immune regulation and inflammatory responses. This study aims to investigate the function of BAP1 in sepsis-induced acute kidney injury (AKI). A mouse model with sepsis-induced AKI was induced by cecal ligation and puncture, and renal tubular epithelial cells (RTECs) were treated with lipopolysaccharide (LPS) to mimic an AKI condition in vitro. BAP1 was significantly poorly expressed in the kidney tissues of model mice and the LPS-treated RTECs. Artificial upregulation of BAP1 ameliorated the pathological changes, tissue injury and inflammatory responses in kidney tissues of the mice, and it reduced the LPS-induced injury and apoptosis of the RTECs. BAP1 was found to interact with BRCA1 and enhance stability of BRCA1 protein through deubiquitination modification. Further downregulation of BRCA1 activated the nuclear factor-kappa B (NF-κB) signaling pathway and blocked the protective roles of BAP1 in sepsis-induced AKI. In conclusion, this study demonstrates that BAP1 protects mice from sepsis-induced AKI through enhancing stability of BRCA1 protein and inactivating the NF-κB signaling.

Liensinine pretreatment reduces inflammation, oxidative stress, apoptosis, and autophagy to alleviate sepsis acute kidney injury

Liensinine is mainly derived from alkaloids extracted and isolated from lotus seeds (Nelumbo nucifera Gaertn). It possesses anti-inflammatory, and antioxidant, according to contemporary pharmacological investigations. However, the effects and therapeutic mechanisms of liensinine on acute kidney injury (AKI) models of sepsis are unclear. To gain insight into these mechanisms, we established a sepsis kidney injury model by LPS injection of mice treated with liensinine, and stimulation of HK-2 with LPS in vitro and treated with liensinine and inhibitors of p38 MAPK, JNK MAPK. We first found that liensinine significantly reduced kidney injury in sepsis mice, while suppressing excessive inflammatory responses, restoring renal oxidative stress-related biomarkers, reducing increased apoptosis in TUNEL-positive cells and excessive autophagy, and that this process was accompanied by an increase in JNK/ p38-ATF 2 axis. In vitro experiments further demonstrated that lensinine reduced the expression of KIM-1, NGAL, inhibited pro- and anti-inflammatory secretion disorders, regulated the activation of the JNK/p38-ATF 2 axis, and reduced the accumulation of ROS, as well as the reduction of apoptotic cells detected by flow cytometry, and that this process played the same role as that of p38 MAPK, JNK MAPK inhibitors. We speculate that liensinine and p38 MAPK, JNK MAPK inhibitors may act on the same targets and could be involved in the mechanism of alleviating sepsis kidney injury in part through modulation of the JNK/p38-ATF 2 axis. Our study demonstrates that lensinine is a potential drug and thus provides a potential avenue for the treatment of AKI.

Geranylgeranylacetone, an inducer of heat shock protein 70, attenuates pulmonary fibrosis via inhibiting NF-κB/NOX4/ROS signalling pathway in vitro and in vivo

Idiopathic pulmonary fibrosis (IPF) is a devastating and progressive pulmonary disease which is characterized by epithelial cell damage and extracellular collagen deposition. To date, the therapeutic options for IPF are still very limited, so the relevant mechanisms need to be explored. Heat shock protein 70 (HSP70), which has protective versus antitumor effects on cells under stress, is a member of the heat shock protein family. In the current study, qRT-PCR, western blotting, immunofluorescence staining, and migration assays were used to explore the Epithelial-mesenchymal transition (EMT) process in BEAS-2B cells. Moreover, the role of GGA in the process of pulmonary fibrosis was detected by HE, Masson staining, pulmonary function test and immunohistochemistry in C57BL/6 mice. Our results indicated that GGA, as an inducer of HSP70, enhanced the transformation of BEAS-2B cells from epithelial to mesenchymal cells through the NF-κB/NOX4/ROS (reactive oxygen species) signalling pathway and could significantly reduce apoptosis of BEAS-2B cells induced by TGF-β1(Transforming growth factor β1) in vitro. In vivo studies demonstrated that HSP70-inducing drugs, such as GGA, attenuated pulmonary fibrosis progression induced by bleomycin (BLM). Collectively, these results suggested that overexpression of HSP70 attenuated pulmonary fibrosis induced by BLM in C57BL/6 mice and EMT process induced by TGF-β1 through NF-κB/NOX4/ROS pathway in vitro. Thus, HSP70 might be a potential therapeutic strategy for human lung fibrosis.

Antioxidant nanozymes in kidney injury: mechanism and application

Excessive production of reactive oxygen species (ROS) in the kidneys is involved in the pathogenesis of kidney diseases, such as acute kidney injury (AKI) and diabetic kidney disease (DKD), and is the main reason for the progression of kidney injury. ROS can easily lead to lipid peroxidation and damage the tubular epithelial cell membrane, proteins and DNA, and other molecules, which can trigger cellular oxidative stress. Effective scavenging of ROS can delay or halt the progression of kidney injury by reducing inflammation and oxidative stress. With the development of nanotechnology and an improved understanding of nanomaterials, more researchers are applying nanomaterials with antioxidant activity to treat kidney injury. This article reviews the detailed mechanism between ROS and kidney injury, as well as the applications of nanozymes with antioxidant effects based on different materials for various kidney injuries. To better guide the applications of antioxidant nanozymes in kidney injury and other inflammatory diseases, at the end of this review we also summarize the aspects of nanozymes that need to be improved. An in-depth understanding of the role played by ROS in the occurrence and progression of kidney injury and the mechanism by which antioxidant nanozymes reduce oxidative stress is conducive to improving the therapeutic effect in kidney injury and inflammation-related diseases.

New insights into Sirt1: potential therapeutic targets for the treatment of cerebral ischemic stroke

Ischemic stroke is one of the main causes of mortality and disability worldwide. However, the majority of patients are currently unable to benefit from intravenous thrombolysis or intravascular mechanical thrombectomy due to the limited treatment windows and serious complications. Silent mating type information regulation 2 homolog 1 (Sirt1), a nicotine adenine dinucleotide-dependent enzyme, has emerged as a potential therapeutic target for ischemic stroke due to its ability to maintain brain homeostasis and possess neuroprotective properties in a variety of pathological conditions for the central nervous system. Animal and clinical studies have shown that activation of Sirt1 can lessen neurological deficits and reduce the infarcted volume, offering promise for the treatment of ischemic stroke. In this review, we summarized the direct evidence and related mechanisms of Sirt1 providing neuroprotection against cerebral ischemic stroke. Firstly, we introduced the protein structure, catalytic mechanism and specific location of Sirt1 in the central nervous system. Secondly, we list the activators and inhibitors of Sirt1, which are primarily divided into three categories: natural, synthetic and physiological. Finally, we reviewed the neuroprotective effects of Sirt1 in ischemic stroke and discussed the specific mechanisms, including reducing neurological deficits by inhibiting various programmed cell death such as pyroptosis, necroptosis, ferroptosis, and cuproptosis in the acute phase, as well as enhancing neurological repair by promoting angiogenesis and neurogenesis in the later stage. Our review aims to contribute to a deeper understanding of the critical role of Sirt1 in cerebral ischemic stroke and to offer novel therapeutic strategies for this condition.

Maresin-1 protects against pulmonary arterial hypertension by improving mitochondrial homeostasis through ALXR/HSP90α axis

AIMS

Pulmonary arterial hypertension (PAH) is a progressive and lethal disease characterized by continuous proliferation of pulmonary arterial smooth muscle cell (PASMCs) and increased pulmonary vascular remodeling. Maresin-1 (MaR1) is a member of pro-resolving lipid mediators and exhibits protective effects on various inflammation-related diseases. Here we aimed to study the role of MaR1 in the development and progression of PAH and to explore the underlying mechanisms.

METHODS AND RESULTS

We evaluated the effect of MaR1 treatment on PAH in both monocrotaline (MCT)-induced rat and hypoxia+SU5416 (HySu)-induced mouse models of pulmonary hypertension (PH). Plasma samples were collected from patients with PAH and rodent PH models to examine MaR1 production. Specific shRNA adenovirus or inhibitors were used to block the function of MaR1 receptors. The data showed that MaR1 significantly prevented the development and blunted the progression of PH in rodents. Blockade of the function of MaR1 receptor ALXR, but not LGR6 or RORα, with BOC-2, abolished the protective effect of MaR1 against PAH development and reduced its therapeutic potential. Mechanistically, we demonstrated that the MaR1/ALXR axis suppressed hypoxia-induced PASMCs proliferation and alleviated pulmonary vascular remodeling by inhibiting mitochondrial accumulation of heat shock protein 90α (HSP90α) and restoring mitophagy.

CONCLUSION

MaR1 protects against PAH by improving mitochondrial homeostasis through ALXR/HSP90α axis and represents a promising target for PAH prevention and treatment.

Maresin: Macrophage Mediator for Resolving Inflammation and Bridging Tissue Regeneration-A System-Based Preclinical Systematic Review

Maresins are lipid mediators derived from omega-3 fatty acids with anti-inflammatory and pro-resolving properties, capable of promoting tissue regeneration and potentially serving as a therapeutic agent for chronic inflammatory diseases. The aim of this review was to systematically investigate preclinical and clinical studies on maresin to inform translational research. Two independent reviewers performed comprehensive searches with the term "Maresin (NOT) Review" on PubMed. A total of 137 studies were included and categorized into 11 human organ systems. Data pertinent to clinical translation were specifically extracted, including delivery methods, optimal dose response, and specific functional efficacy. Maresins generally exhibit efficacy in treating inflammatory diseases, attenuating inflammation, protecting organs, and promoting tissue regeneration, mostly in rodent preclinical models. The nervous system has the highest number of original studies (n = 25), followed by the cardiovascular system, digestive system, and respiratory system, each having the second highest number of studies (n = 18) in the field. Most studies considered systemic delivery with an optimal dose response for mouse animal models ranging from 4 to 25 μg/kg or 2 to 200 ng via intraperitoneal or intravenous injection respectively, whereas human in vitro studies ranged between 1 and 10 nM. Although there has been no human interventional clinical trial yet, the levels of MaR1 in human tissue fluid can potentially serve as biomarkers, including salivary samples for predicting the occurrence of cardiovascular diseases and periodontal diseases; plasma and synovial fluid levels of MaR1 can be associated with treatment response and defining pathotypes of rheumatoid arthritis. Maresins exhibit great potency in resolving disease inflammation and bridging tissue regeneration in preclinical models, and future translational development is warranted.

Cepabiflas B and C as Novel Anti-Inflammatory and Anti-Apoptotic Agents against Endotoxin-Induced Acute Kidney and Hepatic Injury in Mice: Impact on Bax/Bcl2 and Nrf2/NF-κB Signalling Pathways

Cepabiflas B and C (CBs) are flavonoid dimers separated from Allium cepa. They demonstrated antioxidant and α-glucosidase and protein tyrosine phosphatase 1B inhibition capacities. However, their anti-inflammatory activities and their effects on endotoxemia are unknown. The current study aimed at exploring the protective activities of CBs on lipopolysaccharide (LPS)-induced kidney and liver damage in mice and investigating the possible molecular mechanisms. Mice were orally treated with a low (40 mg/kg) or high (60 mg/kg) dose of CBs for five days prior to a single intraperitoneal injection of LPS (10 mg/kg). Samples of serum and hepatic and kidney tissues were collected 24 h after the LPS challenge. Changes in serum indices of hepatic and renal injury, pathological changes, molecular biological parameters, and proteins/genes related to inflammation and apoptosis of these organs were estimated. LPS injection resulted in deleterious injury to both organs as indicated by elevation of serum ALT, AST, creatinine, and BUN. The deteriorated histopathology of hepatic and renal tissues confirmed the biochemical indices. CBs treated groups showed a reduction in these parameters and improved histopathological injurious effects of LPS. LPS-induced hepatorenal injury was linked to elevated oxidative stress as indicated by high levels of MDA, 4-HNE, as well as repressed antioxidants (TAC, SOD, and GSH) in hepatic and kidney tissues. This was accompanied with suppressed Nrf2/HO-1 activity. Additionally, there was a remarkable inflammatory response in both organs as NF-κB signalling was activated and high levels of downstream cytokines were produced following the LPS challenge. Apoptotic changes were observed as the level and gene expression of Bax and caspase-3 were elevated along with declined level and gene expression of Bcl2. Interestingly, CBs reversed all these molecular and genetic changes and restricted oxidative inflammatory and apoptotic parameters after LPS-injection. Collectedly, our findings suggested the marked anti-inflammatory and anti-apoptotic activity of CBs which encouraged its use as a new candidate for septic patients.

The pro-resolving lipid mediator Maresin 1 ameliorates pain responses and neuroinflammation in the spared nerve injury-induced neuropathic pain: A study in male and female mice

Specialized pro-resolving mediators (SPMs) have recently emerged as promising therapeutic approaches for neuropathic pain (NP). We evaluated the effects of oral treatment with the SPM Maresin 1 (MaR1) on behavioral pain responses and spinal neuroinflammation in male and female C57BL/6J mice with spared nerve injury (SNI)-induced NP. MaR1, or vehicle, was administered once daily, on post-surgical days 3 to 5, by voluntary oral intake. Sensory-discriminative and affective-motivational components of pain were evaluated with von Frey and place escape/avoidance paradigm (PEAP) tests, respectively. Spinal microglial and astrocytic activation were assessed by immunofluorescence, and the spinal concentration of cytokines IL-1β, IL-6, IL-10, and macrophage colony-stimulating factor (M-CSF) were evaluated by multiplex immunoassay. MaR1 treatment reduced SNI-induced mechanical hypersensitivity on days 7 and 11 in both male and female mice, and appeared to ameliorate the affective component of pain in males on day 11. No definitive conclusions could be drawn about the impact of MaR1 on the affective-motivational aspects of pain in female mice, since repeated suprathreshold mechanical stimulation of the affected paw in the dark compartment did not increase the preference of vehicle-treated SNI females for the light side, during the PEAP test session (a fundamental assumption for PAEP's validity). MaR1 treatment also reduced ipsilateral spinal microglial and astrocytic activation in both sexes and marginally increased M-CSF in males, while not affecting cytokines IL-1β, IL-6 and IL-10 in either sex. In summary, our study has shown that oral treatment with MaR1 (i) produces antinociception even in an already installed peripheral NP mouse model, and (ii) this antinociception may extend for several days beyond the treatment time-frame. These therapeutic effects are associated with attenuated microglial and astrocytic activation in both sexes, and possibly involve modulation of M-CSF action in males.

Maresin1: A multifunctional regulator in inflammatory bone diseases

Inflammation plays a crucial role in the physical response to danger signals, the elimination of toxic stimuli, and the restoration of homeostasis. However, dysregulated inflammatory responses lead to tissue damage, and chronic inflammation can disrupt osteogenic-osteoclastic homeostasis, ultimately leading to bone loss. Maresin1 (MaR1), a member of the specialized pro-resolving mediators (SPMs) family, has been found to possess significant anti-inflammatory, anti-allergic, pro-hemolytic, pro-healing, and pain-relieving properties. MaR1 is synthesized by macrophages (Mφs) and omega-3 fatty acids, and it may have the potential to promote bone homeostasis and treat inflammatory bone diseases. MaR1 has been found to stimulate osteoblast proliferation through leucine-rich repeat G protein-coupled receptor 6 (LGR6). It also activates Mφ phagocytosis and M2-type polarization, which helps to control the immune system. MaR1 can regulate T cells to exert anti-inflammatory effects and inhibit neutrophil infiltration and recruitment. In addition, MaR1 is involved in antioxidant signaling, including nuclear factor erythroid 2-related factor 2 (NRF2). It has also been found to promote the autophagic behavior of periodontal ligament stem cells, stimulate Mφs against pathogenic bacteria, and regulate tissue regeneration and repair. In summary, this review provides new information and a comprehensive overview of the critical roles of MaR1 in inflammatory bone diseases, indicating its potential as a therapeutic approach for managing skeletal metabolism and inflammatory bone diseases.

NOX4 is a potential therapeutic target in septic acute kidney injury by inhibiting mitochondrial dysfunction and inflammation

Rationale: Sepsis is a severe clinical syndrome featured through organ dysfunction due to infection, while the accompanying acute kidney injury (AKI) is linked to significant incidence of morbidity as well as mortality. Recently, emerging evidence has revealed that nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (NOX4) is implicated in various renal diseases, while its role and modulation in septic acute kidney injury (S-AKI) remains largely unknown. Methods: In vivo, S-AKI in wild-type and renal tubular epithelial cell (RTEC)-specific NOX4 knockout mice was induced by lipopolysaccharides (LPS) injection or cecal ligation and puncture (CLP). In vitro, TCMK-1 (mouse kidney tubular epithelium cell line) cells were treated with LPS. Serum and supernatant biochemical, mitochondrial dysfunctional, inflammatory and apoptotic parameters were measured and compared across groups. The activation of reactive oxygen species (ROS) and NF-κB signaling was also assessed. Results: NOX4 was predominantly upregulated in RTECs of S-AKI mouse model induced by LPS/CLP and cultured TCMK-1 cells exposed to LPS. RTEC-specific deletion of NOX4 or pharmacological inhibition of NOX4 by GKT137831 both alleviated LPS/CLP-injured renal function and pathology in mice. Furthermore, NOX4 inhibition alleviated mitochondrial dysfunction supported by ultrastructural damage, reduction of ATP production and mitochondrial dynamics imbalance, together with inflammation and apoptosis in kidney injured by LPS/CLP and TCMK-1 cells injured by LPS, while NOX4 overexpression aggravated the above-mentioned indices in TCMK-1 cells with LPS stimulation. Mechanism-wise, the raised NOX4 in RTECs may induce ROS and NF-κB signaling activation in S-AKI. Conclusions: Collectively, genetic or pharmacological inhibition of NOX4 protects from S-AKI by reducing generation of ROS and activation of NF-κB signal, which suppress mitochondrial dysfunction, inflammation together with apoptosis. NOX4 may act as a novel target for the S-AKI therapy.

Antioxidant, Antiapoptotic, and Anti-Inflammatory Effects of Hesperetin in a Mouse Model of Lipopolysaccharide-Induced Acute Kidney Injury

Sepsis is a severe inflammatory condition that can cause organ dysfunction, including acute kidney injury (AKI). Hesperetin is a flavonoid aglycone that has potent antioxidant and anti-inflammatory properties. However, the effect of hesperetin on septic AKI has not yet been fully investigated. This study examined whether hesperetin has a renoprotective effect on lipopolysaccharide (LPS)-induced septic AKI. Hesperetin treatment ameliorated histological abnormalities and renal dysfunction in LPS-injected mice. Mechanistically, hesperetin attenuated LPS-induced oxidative stress, as evidenced by the suppression of lipid and DNA oxidation. This beneficial effect of hesperetin was accompanied by downregulation of the pro-oxidant NADPH oxidase 4, restoration of glutathione levels, and activation of antioxidant enzymes. This flavonoid compound also inhibited apoptotic cell death via suppression of p53-dependent caspase-3 pathway. Furthermore, hesperetin alleviated Toll-like receptor 4-mediated cytokine production and macrophage infiltration. Our findings suggest that hesperetin ameliorates LPS-induced renal structural and functional injury through suppressing oxidative stress, apoptosis, and inflammation.

Blockade of Indoleamine 2,3-Dioxygenase attenuates lipopolysaccharide-induced kidney injury by inhibiting TLR4/NF-κB signaling

Blockade of indoleamine 2,3-dioxygenase (IDO) has been shown to alleviate lipopolysaccharide (LPS)-induced endotoxic shock and reduce sepsis mortality, but its effect on LPS-induced kidney damage has not been reported. Herein, we established a mouse kidney injury model by intraperitoneal injection of 10 mg/kg LPS and established an in vitro renal tubular epithelial cell injury model by stimulating TCMK-1 cells with 10 mg/L LPS. We found that pretreatment with 1-methyl tryptophan (1-MT), an IDO inhibitor, significantly improved LPS-induced mouse survival, and IDO knockout (KO) mice also had higher survival rates after LPS exposure than wild-type mice. At the same time, IDO KO or pretreatment with 1-MT not only reduced serum creatinine, blood urea nitrogen, renal tubular injury pathological score, but also inflammatory factors and oxidative stress status in serum or kidney of LPS-exposed mice. In vitro, blockade of IDO with 1-MT significantly inhibited LPS-induced apoptosis, inflammation and oxidative stress in TCMK-1 cells. In addition, blockade of IDO significantly inhibited LPS-activated TLR4/NF-κB signaling pathway in kidney of mice or in TCMK-1 cells. In conclusion, our results suggested that blockade of IDO attenuated kidney inflammation, apoptosis and oxidative stress to protect against LPS-induced septic kidney injury via inhibiting the TLR4/NF-κB signaling pathway.

Kaempferol Reverses Acute Kidney Injury in Septic Model by Inhibiting NF-κB/AKT Signaling Pathway

Sepsis is the main cause of acute kidney injury (AKI), mainly due to systemic immune dysregulation. Kaempferol (KAE) is a natural flavonoid compound with multiple biological activities including anti-inflammatory, antioxidant, and antiapoptotic properties. In this study, we constructed a sepsis-induced AKI mouse model and an LPS-induced glomerular mesangial cell (HK-2) in vitro sepsis AKI model. We found that KAE ameliorated sepsis-induced renal pathological damage, reversed renal function damage, and inhibited p-p65 and p-AKT protein expression. In addition, KAE reversed LPS-induced proliferation and inhibited apoptosis in HK-2 cells. These studies suggest that KAE reverses sepsis by inhibiting activation of the NF-κB/AKT pathway to reverse acute kidney injury.

Maresin1 can be a potential therapeutic target for nerve injury

Nerve injury significantly affects human motor and sensory function due to destruction of the integrity of nerve structure. In the wake of nerve injury, glial cells are activated, and synaptic integrity is destroyed, causing inflammation and pain hypersensitivity. Maresin1, an omega-3 fatty acid, is a derivative of docosahexaenoic acid. It has showed beneficial effects in several animal models of central and peripheral nerve injuries. In this review, we summarize the anti-inflammatory, neuroprotective and pain hypersensitivity effects of maresin1 in nerve injury and provide a theoretical basis for the clinical treatment of nerve injury using maresin1.

Resolvin D5 (RvD5) Reduces Renal Damage Caused by LPS Endotoxemia in Female Mice

In self-revolving gram-negative Escherichia coli infection, Resolvin D5 (RvD5) was found to enhance bacteria phagocytosis and reduce the production of inflammatory mediators, contributing to the resolution of infection. LPS (lipopolysaccharide) is a gram-negative bacterial structure product which activates the immune system and, at high doses, leads to endotoxemia. To our knowledge, the effect of RvD5 against LPS endotoxemia has not been investigated to date. Female Swiss mice received an i.p. treatment with RvD5 (0.1, 1 or 10 ng/animal). After 1 h, they were stimulated with LPS (10 mg/kg, i.v.), and samples were collected after additional 6 h. The resulting data demonstrated that RvD5 protected the kidneys (urea and creatinine serum levels) from tissue injury. These effects were related to an improvement in histopathological parameters and a reduction of enzymatic markers of leukocyte infiltration, pro-inflammatory cytokine (IL-1β, TNF-α, and IL-6) production, and oxidative stress. Antioxidant markers were also increased by RvD5, but IL-10 (an anti-inflammatory cytokine) levels were unaltered. We also observed that RvD5 reduced the infiltration of CD45⁺ hematopoietic cells into the kidneys, reduced the activation of NFκB and promoted the Nrf2 pathway by reducing Keap-1 levels. Our data indicate that RvD5 may be a therapeutic possibility to reduce kidney lesions in LPS endotoxemia.

Ginsenoside Rg1 ameliorates sepsis-induced acute kidney injury by inhibiting ferroptosis in renal tubular epithelial cells

Acute kidney injury (AKI) represents a prevailing complication of sepsis, and its onset involves ferroptosis. Ginsenoside Rg1 exerts a positive effect on kidney diseases. This study explored the action of ginsenoside Rg1 in sepsis-induced AKI (SI-AKI) by regulating ferroptosis in renal tubular epithelial cells (TECs). Sepsis rat models were established using cecal ligation and puncture (CLP) and cell models were established by treating human renal TECs (HK-2) with LPS to induce ferroptosis. Serum creatinine (SCr) and blood urea nitrogen (BUN) and urine KIM1 contents in rats were determined by ELISA kits. Kidney tissues were subjected to immunohistochemical and H&E stainings. Iron concentration, malondialdehyde (MDA), glutathione (GSH), and ferroptosis-related protein (ferritin light chain [FTL], ferritin heavy chain [FTH], GSH peroxidase 4 [GPX4], and Ferroptosis suppressor protein 1 [FSP1]) levels in kidney tissues and HK-2 cells were measured using ELISA kits and Western blotting. HK-2 cell viability was detected by cell counting kit-8, and cell death was observed via propidium iodide staining. Reactive oxygen species accumulation in cells was detected using C11 BODIPY 581/591 as a molecular probe. In CLP rats, ginsenoside Rg1 reduced SCr, BUN, KIM1, and NGAL levels, thus palliating SI-AKI. Additionally, ginsenoside Rg1 decreased iron content, FTL, FTH, and MDA levels, and elevated GPX4, FSP1, and GSH levels, thereby inhibiting lipid peroxidation and ferroptosis. Moreover, FSP1 knockdown annulled the inhibition of ginsenoside Rg1 on ferroptosis. In vitro experiments, ginsenoside Rg1 raised HK-2 cell viability and lowered iron accumulation and lipid peroxidation during ferroptosis, and its antiferroptosis activity was dependent on FSP1. Ginsenoside Rg1 alleviates SI-AKI, possibly resulting from inhibition of ferroptosis in renal TECs through FSP1.

Methotrexate-Induced Alteration of Renal Aquaporins 1 and 2, Oxidative Stress and Tubular Apoptosis Can Be Attenuated by Omega-3 Fatty Acids Supplementation

Methotrexate (MTX) is a potent anti-cancer drug, commonly associated with nephrotoxicity via the induction of oxidative stress and apoptosis with alteration of renal water channel proteins, namely aquaporins (AQPs). Omega-3 long-chain polyunsaturated fatty acids (LC-PUFA) have shown cytoprotective effects through their anti-oxidant and antiapoptotic activities. The present study aims for the first time to explore the role of LC-PUFA against MTX-induced nephrotoxicity. Rats were divided into the following groups: saline control, LC-PUFA control, MTX, MTX + LC-PUFA (150 mg/kg), or MTX + LC-PUFA (300 mg/kg). Then, H&E staining and immunohistochemical staining for the anti-apoptosis marker B-cell lymphoma 2 (BCL-2), the apoptosis marker BCL2-Associated X Protein (BAX), the proinflammatory marker Nuclear factor kappa B (NF-kB), AQPs 1 and 2 were performed in kidney sections with an assessment of renal oxidative stress. The MTX caused a renal histopathological alteration, upregulated renal BAX and NF-kB, downregulated Bcl-2 and AQP1, altered the distribution of AQP2, and caused oxidative stress. The LC-PUFA attenuated the pathological changes and decreased renal BAX and NF-kB, increased BCL-2 and AQP1, restored the normal distribution of AQP2, and decreased the oxidative stress. Therefore, LC-PUFA is a good adjuvant to MTX to prevent its adverse effects on kidneys through its antiapoptotic, antioxidant, and anti-inflammatory effect and its role in the restoration of the expression of AQPs 1 and 2.

Faecalibacterium prausnitzii Attenuates CKD via Butyrate-Renal GPR43 Axis

BACKGROUND

Despite available clinical management strategies, chronic kidney disease (CKD) is associated with severe morbidity and mortality worldwide, which beckons new solutions. Host-microbial interactions with a depletion of Faecalibacterium prausnitzii in CKD are reported. However, the mechanisms about if and how F prausnitzii can be used as a probiotic to treat CKD remains unknown.

METHODS

We evaluated the microbial compositions in 2 independent CKD populations for any potential probiotic. Next, we investigated if supplementation of such probiotic in a mouse CKD model can restore gut-renal homeostasis as monitored by its effects on suppression on renal inflammation, improvement in gut permeability and renal function. Last, we investigated the molecular mechanisms underlying the probiotic-induced beneficial outcomes.

RESULTS

We observed significant depletion of Faecalibacterium in the patients with CKD in both Western (n=283) and Eastern populations (n=75). Supplementation of F prausnitzii to CKD mice reduced renal dysfunction, renal inflammation, and lowered the serum levels of various uremic toxins. These are coupled with improved gut microbial ecology and intestinal integrity. Moreover, we demonstrated that the beneficial effects in kidney induced by F prausnitzii-derived butyrate were through the GPR (G protein-coupled receptor)-43.

CONCLUSIONS

Using a mouse CKD model, we uncovered a novel beneficial role of F prausnitzii in the restoration of renal function in CKD, which is, at least in part, attributed to the butyrate-mediated GPR-43 signaling in the kidney. Our study provides the necessary foundation to harness the therapeutic potential of F prausnitzii for ameliorating CKD.

TRPM7 promotes lipopolysaccharide-induced inflammatory dysfunction in renal tubular epithelial cells

BACKGROUND

Sepsis-associated acute kidney injury (S-AKI) has been reported to affect 30%-50% of all sepsis patients; this condition is associated with a notable fatality rate. Following lipopolysaccharide (LPS) stimulation, the expression of transient receptor potential cation channel subfamily M member 7 (TRPM7), a nonselective cation channel expressed by the renal tubular epithelial cells (RTECs) was found to be upregulated. We aimed to determine how TRPM7 functions in S-AKI.

METHODS

To establish an in vitro model of S-AKI, RTECs were treated with LPS. The effect of TRPM7 knockdown on cell viability, lactate dehydrogenase (LDH) release, apoptosis, inflammation, and oxidative stress was studied. The binding site between Kruppel-like factor 2 (KLF2) and TRPM7 was predicted using JASPAR. The influence of KLF2 on the regulatory roles of TRPM7 in cells, as well as the effect of their knockdown on the MAPK signaling pathway, was investigated.

RESULTS

TRPM7 was upregulated in LPS-treated cells, and knocking improved cell viability, reduced LDH levels, and minimized apoptosis, inflammation, and oxidative stress. KLF2 was shown to be associated with TRPM7 and its level decreased in LPS-treated cells. KLF2 knockdown increased TRPM7 expression and reversed the effects of TRPM7 knockdown in LPS-treated cells, including suppression of p38 MAPK, ERK1/2, and JNK activation.

CONCLUSION

Taken together, our results show that TRPM7 is negatively regulated by KLF2 and promotes LPS-induced inflammatory dysfunction by activating the MAPK pathway in RTECs. The theoretical foundation for the prevention and management of S-AKI is laid out in this article.