Erythropoietin prevents sepsis-related acute kidney injury in rats by inhibiting NF-κB and upregulating endothelial nitric oxide synthase

Biotherapy of experimental acute kidney injury: emerging novel therapeutic strategies

Acute kidney injury (AKI) is a complex and heterogeneous disease with high incidence and mortality, posing a serious threat to human life and health. Usually, in clinical practice, AKI is caused by crush injury, nephrotoxin exposure, ischemia-reperfusion injury, or sepsis. Therefore, most AKI models for pharmacological experimentation are based on this. The current research promises to develop new biological therapies, including antibody therapy, non-antibody protein therapy, cell therapy, and RNA therapy, that could help mitigate the development of AKI. These approaches can promote renal repair and improve systemic hemodynamics after renal injury by reducing oxidative stress, inflammatory response, organelles damage, and cell death, or activating cytoprotective mechanisms. However, no candidate drugs for AKI prevention or treatment have been successfully translated from bench to bedside. This article summarizes the latest progress in AKI biotherapy, focusing on potential clinical targets and novel treatment strategies that merit further investigation in future pre-clinical and clinical studies.

Anti-inflammatory Effect of Low-Intensity Ultrasound in Septic Rats

OBJECTIVE

Sepsis is a severe systemic inflammatory response caused by infection. Here, the spleen region of Sprague-Dawley (SD) rats with sepsis was irradiated with low-intensity ultrasound (LIUS) to explore the regulation of inflammation and its mechanism by LIUS.

METHODS

In this study, 30 rats used for survival analysis were randomly divided into the sham-operated group (Sham, n = 10), the group in which sepsis was induced by cecal ligation and puncture (CLP, n = 10) and the group treated with LIUS immediately after CLP (LIUS, n = 10). The other 120 rats were randomly divided into the aforementioned three groups for detection at each time point. The parameters used in the LIUS group were 200 mW/cm², 0.37 MHz, 20% duty cycle and 20 min, and no ultrasonic energy was produced in the Sham and CLP groups. Seven-day survival rate, histopathology and expression of inflammatory factors and proteins were evaluated in the three groups.

RESULTS

LIUS was able to improve the survival rate of septic SD rats (p < 0.05), significantly inhibit the expression of tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), interleukin 6 (IL-6) and nuclear factor-κB p65 (NF-κB p65) (p < 0.05) and restore the ultrastructure of the spleen.

CONCLUSION

Our study determined that LIUS can relieve spleen damage and alleviate severe cytokine storm to improve survival outcomes in septic SD rats, and its mechanism may be related to the inhibition of the NF-κB signaling pathway by downregulation of IL-1β.

Erythropoietin promotes energy metabolism to improve LPS-induced injury in HK-2 cells via SIRT1/PGC1-α pathway

Acute kidney injury (AKI) is one of frequent complications of sepsis with high mortality. Mitochondria is the center of energy metabolism participating in the pathogenesis of sepsis-associated AKI, and SIRT1/PGC1-α signaling pathway plays a crucial role in the modulation of energy metabolism. Erythropoietin (EPO) exerts protective functions on chronic kidney disease. We aimed to assess the effects of EPO on cell damage and energy metabolism in a cell model of septic AKI. Renal tubular epithelial cells HK-2 were treated with LPS and human recombinant erythropoietin (rhEPO). Cell viability was detected by CCK-8 and mitochondrial membrane potential was determined using JC-1 fluorescent probe. Then the content of ATP, ADP and NADPH, as well as lactic acid, were measured for the assessment of energy metabolism. Oxidative stress was evaluated by detecting the levels of ROS, MDA, SOD and GSH. Pro-inflammatory cytokines, including TNF-α, IL-6, and IL-1β, were measured with ELISA. Moreover, qRT-PCR and western blot were performed to detect mRNA and protein expressions. shSIRT1 was used to knockdown SIRT1, while EX527 and SR-18292 were applied to inhibit SIRT1 and PGC1-α, respectively, to investigate the regulatory mechanism of rhEPO on inflammatory injury and energy metabolism. In LPS-exposed HK-2 cells, rhEPO attenuated cell damage, inflammation and abnormal energy metabolism, as indicated by the elevated cell viability, the inhibited oxidative stress, cell apoptosis and inflammation, as well as the increased mitochondrial membrane potential and energy metabolism. However, these protective effects induced by rhEPO were reversed after SIRT1 or PGC1-α inhibition. EPO activated SIRT1/PGC1-α pathway to alleviate LPS-induced abnormal energy metabolism and cell damage in HK-2 cells. Our study suggested that rhEPO played a renoprotective role through SIRT1/PGC1-α pathway, which supported its therapeutic potential in septic AKI.

Carbon monoxide mechanism of protection against renal ischemia and reperfusion injury

Carbon monoxide is quickly moving past its historic label as a molecule once feared, to a therapeutic drug that modulates inflammation. The development of carbon monoxide releasing molecules and utilization of heme oxygenase-1 inducers have shown carbon monoxide to be a promising therapy in reducing renal ischemia and reperfusion injury and other inflammatory diseases. In this review, we will discuss the developments and application of carbon monoxide releasing molecules in renal ischemia and reperfusion injury, and transplantation. We will review the anti-inflammatory mechanisms of carbon monoxide in respect to mitigating apoptosis, suppressing dendritic cell maturation and signalling, inhibiting toll-like receptor activation, promoting anti-inflammatory responses, and the effects on renal vasculature.

The role of nitric oxide in sepsis-associated kidney injury

Sepsis is one of the leading causes of acute kidney injury (AKI), and several mechanisms including microcirculatory alterations, oxidative stress, and endothelial cell dysfunction are involved. Nitric oxide (NO) is one of the common elements to all these mechanisms. Although all three nitric oxide synthase (NOS) isoforms are constitutively expressed within the kidneys, they contribute in different ways to nitrergic signaling. While the endothelial (eNOS) and neuronal (nNOS) isoforms are likely to be the main sources of NO under basal conditions and participate in the regulation of renal hemodynamics, the inducible isoform (iNOS) is dramatically increased in conditions such as sepsis. The overexpression of iNOS in the renal cortex causes a shunting of blood to this region, with consequent medullary ischemia in sepsis. Differences in the vascular reactivity among different vascular beds may also help to explain renal failure in this condition. While most of the vessels present vasoplegia and do not respond to vasoconstrictors, renal microcirculation behaves differently from nonrenal vascular beds, displaying similar constrictor responses in control and septic conditions. The selective inhibition of iNOS, without affecting other isoforms, has been described as the ideal scenario. However, iNOS is also constitutively expressed in the kidneys and the NO produced by this isoform is important for immune defense. In this sense, instead of a direct iNOS inhibition, targeting the NO effectors such as guanylate cyclase, potassium channels, peroxynitrite, and S-nitrosothiols, may be a more interesting approach in sepsis-AKI and further investigation is warranted.

Disruption of Kidney-Immune System Crosstalk in Sepsis with Acute Kidney Injury: Lessons Learned from Animal Models and Their Application to Human Health

In addition to being a leading cause of morbidity and mortality worldwide, sepsis is also the most common cause of acute kidney injury (AKI). When sepsis leads to the development of AKI, mortality increases dramatically. Since the cardinal feature of sepsis is a dysregulated host response to infection, a disruption of kidney-immune crosstalk is likely to be contributing to worsening prognosis in sepsis with acute kidney injury. Since immune-mediated injury to the kidney could disrupt its protein manufacturing capacity, an investigation of molecules mediating this crosstalk not only helps us understand the sepsis immune response, but also suggests that their supplementation could have a therapeutic effect. Erythropoietin, vitamin D and uromodulin are known to mediate kidney-immune crosstalk and their disrupted production could impact morbidity and mortality in sepsis with acute kidney injury.

Repurposing of High-Dose Erythropoietin as a Potential Drug Attenuates Sepsis in Preconditioning Renal Injury

Due to (i) the uremia-enhanced sepsis severity, (ii) the high prevalence of sepsis with pre-existing renal injury and (iii) the non-erythropoiesis immunomodulation of erythropoietin (EPO), EPO was tested in sepsis with pre-existing renal injury models with the retrospective exploration in patients. Then, EPO was subcutaneously administered in mice with (i) cecal ligation and puncture (CLP) after renal injury including 5/6 nephrectomy (5/6Nx-CLP) and bilateral nephrectomy (BiNx-CLP) or sham surgery (sham-CLP) and (ii) lipopolysaccharide (LPS) injection, along with testing in macrophages. In patients, the data of EPO administration and the disease characteristics in patients with sepsis-induced acute kidney injury (sepsis-AKI) were evaluated. As such, increased endogenous EPO was demonstrated in all sepsis models, including BiNx-CLP despite the reduced liver erythropoietin receptor (EPOR), using Western blot analysis and gene expression, in liver (partly through hepatocyte apoptosis). A high-dose EPO, but not a low-dose, attenuated sepsis in mouse models as determined by mortality and serum inflammatory cytokines. Furthermore, EPO attenuated inflammatory responses in LPS-activated macrophages as determined by supernatant cytokines and the expression of several inflammatory genes (iNOS, IL-1β, STAT3 and NFκB). In parallel, patients with sepsis-AKI who were treated with the high-dose EPO showed favorable outcomes, particularly the 29-day mortality rate. In conclusion, high-dose EPO attenuated sepsis with preconditioning renal injury in mice possibly through the macrophage anti-inflammatory effect, which might be beneficial in some patients.

MicroRNA‑93 inhibits the apoptosis and inflammatory response of tubular epithelial cells via the PTEN/AKT/mTOR pathway in acute kidney injury

Renal tubular epithelial cell injury is the main cause of septic acute kidney injury (AKI), which is characterized by the excessive inflammatory response and apoptosis. Numerous studies have demonstrated that miRNAs are associated with inflammatory response and apoptosis in numerous diseases. The present study mainly focuses on investigating the association between microRNA (miRNA/miR) expression and inflammatory response and apoptosis in the pathogenesis of AKI. In vitro and in vivo models of AKI were simulated using Escherichia coli lipopolysaccharide (LPS)‑administrated kidney epithelial cells and mice, respectively. The miRNA expression profile was examined using miRNA microarray in kidney tissues. Next, the effects of miR‑93 upregulation on the apoptosis, cytokine expression and oxidative stress in the LPS‑stimulated TCMK‑1 were tested. The target genes of this miRNA were investigated, and the regulatory association between miR‑93 and the AKT/mTOR pathway was investigated. The results demonstrated that miR‑93 was the most downregulated miRNA in mice kidney. Furthermore, in LPS‑induced renal tubular epithelial cells (TECs) injury model, that upregulation of miR‑93 was found to attenuate the apoptosis and inflammatory response, as well as reactive oxygen species generation. Mechanistically, phosphatase and tensin homolog deleted on chromosome 10 (PTEN) was identified as a target of miR‑93. Further experiments revealed that LPS‑induced the decrease of phosphorylated (p)‑AKT and p‑mTOR protein expression in vitro are reversed by the overexpression of miR‑93. The results of the present study suggested that the protective effect of miR‑93 on AKI may be associated with the activation of PTEN/AKT/mTOR pathway. miR‑93 may serve as a potential therapeutic target in sepsis‑induced AKI.

Potential anti-inflammatory effect of erythropoietin in non-clinical studies in vivo: A systematic review

Erythropoietin (EPO) is a hypoxia-induced hormone produced in adult kidneys with erythropoietic and non-erythropoietic effects. In vivo studies represent an important role to comprehend the efficacy and safety in the early phase of repurposing drugs. The aim is to evaluate the potential anti-inflammatory effect of EPO observed in animal models of disease. Following PRISMA statements, electronic database Medline via PubMed platform was used to search articles with the research expression ((erythropoietin [MeSH Terms]) AND (inflammation [MeSH Terms]) AND (disease models, animal [MeSH Terms])). The inclusion criteria were original articles, studies where EPO was administered, studies where inflammation was studied and/or evaluated, non-clinical studies in vivo with rodents, and articles published in English. Thirty-six articles met the criteria for qualitative analysis. Exogenous EPO was used in models of sepsis, traumatic brain injury, and autoimmune neuritis, with an average of 3000 IU/Kg for single and multiple doses, using mice and rats. Biomarkers such as immune-related effectors, cytokines, reactive oxygen species, prostaglandins, and other biomarkers were assessed. EPO has been recognized as a multifunctional cytokine with anti-inflammatory properties, showing its significant effect both in acute and chronic models of inflammation. Further non-clinical studies are suggested for the enlightenment of anti-inflammatory mechanisms of EPO in lower doses, allowing us to understand the translational data for humans.

Green propolis extract attenuates acute kidney injury and lung injury in a rat model of sepsis

Sepsis is the leading cause of acute kidney injury (AKI) and lung injury worldwide. Despite therapeutic advances, sepsis continues to be associated with high mortality. Because Brazilian green propolis (GP) has promising anti-inflammatory, antioxidant, and immunomodulatory properties, we hypothesized that it would protect kidneys and lungs in rats induced to sepsis by cecal ligation and puncture (CLP). Male Wistar rats were divided into groups-control (sham-operated); CLP (CLP only); and CLP + GP (CLP and treatment with GP at 6 h thereafter)-all receiving volume expansion and antibiotic therapy at 6 h after the procedures. By 24 h after the procedures, treatment with GP improved survival, attenuated sepsis-induced AKI, and restored renal tubular function. Whole-blood levels of reduced glutathione were higher in the CLP + GP group. Sepsis upregulated the Toll-like receptor 4/nuclear factor-kappa B axis in lung and renal tissues, as well as increasing inflammatory cytokine levels and macrophage infiltration; all of those effects were attenuated by GP. Treatment with GP decreased the numbers of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling-positive cells in renal and lung tissue, as well as protecting the morphology of the renal mitochondria. Our data open the prospect for clinical trials of the use of GP in sepsis.

Arbutin attenuates LPS-induced acute kidney injury by inhibiting inflammation and apoptosis via the PI3K/Akt/Nrf2 pathway

BACKGROUND

Arbutin (Ar) has anti-oxidative and anti-inflammatory activities. However, the effects of Ar on lipopolysaccharide (LPS)-induced acute kidney injury (AKI) are not clear.

PURPOSE

This study aimed to investigate the effects of Ar on LPS-induced AKI in rats.

METHODS

The possible data regarding the effects of Ar on AKI were collected by network pharmacology research. Histological changes in the kidney and the levels of blood urea nitrogen, serum creatinine, and kidney injury molecule 1 were measured to assess the effects of Ar on renal function in LPS-induced AKI. The levels of inflammatory were detected by live small-animal imaging, cytometric bead array and enzyme linked immunosorbent assay. The levels of reactive oxygen species and apoptosis of primary kidney cells were detected by flow cytometry. The oxidative stress-related markers were detected by the cuvette assay. The TLR4/NF-κB and PI3K/Akt/Nrf2 levels and apoptosis were detected by Western blot analysis. The effects of GDC-0068 (GDC, Akt inhibitor) on Ar interposed on LPS-induced NRK-52e cell apoptosis were investigated by flow cytometry.

RESULTS

The data collected by network pharmacology suggested that Ar might inhibit AKI by exerting an anti-inflammatory effect and regulating the Akt signaling pathway. The experimental results showed that Ar markedly improved renal function, and attenuated inflammation and cell apoptosis via regulating PI3K/Akt/Nrf2 pathway following LPS challenge in vivo, which blocked by GDC effectively in vitro.

CONCLUSION

In a word, this study demonstrated that Ar attenuated LPS-induced AKI by inhibiting inflammation and apoptosis via the PI3K/Akt/Nrf2 pathway.

Disrupted eNOS activity and expression account for vasodilator dysfunction in different stage of sepsis

AIMS

Sepsis is a severe endothelial dysfunction syndrome. The role of endothelial nitric oxide synthase (eNOS) in endothelial dysfunction induced by sepsis is controversial. To explore the role of eNOS in vascular dysfunction.

MAIN METHODS

The effect of sepsis on vasodilation and eNOS levels was examined in septic mouse arteries and in cell models.

KEY FINDINGS

In early sepsis mouse arteries, endothelium-dependent relaxation decreased and phosphorylation of the inhibitory Thr495 site in endothelial nitric oxide synthase increased. Mechanically, the phosphorylation of endothelial nitric oxide synthase at Thr497 in bovine aortic endothelial cells occurred in a protein kinase C-α dependent manner. In late sepsis, both nitric oxide-dependent relaxation responses and endothelial nitric oxide synthase levels were decreased in septic mice arteries. Endothelial nitric oxide synthase levels expression levels decreased in tumor necrosis factor-α-treated human umbilical vein endothelial cells and this could be prevented by the ubiquitin proteasome inhibitor (MG-132). MG-132 could reverse the decrease in endothelial nitric oxide synthase expression and improve nitric oxide-dependent vasodilator dysfunction in septic mice arteries.

SIGNIFICANCE

These data indicate that vasodilator dysfunction is induced by the increased phosphorylation of endothelial nitric oxide synthase in early sepsis and its degradation in late sepsis.

Erythropoietin Ameliorates Ischemia/Reperfusion-Induced Acute Kidney Injury via Inflammasome Suppression in Mice

Acute kidney injury (AKI) is the most common condition in hospitalized patients. As ischemia/reperfusion-induced AKI (IR-AKI) is as a major contributor to end-stage disease, an effective therapeutic intervention for IR-AKI is imperative. Erythropoietin (EPO) is a potent stimulator of erythroid progenitor cells and is significantly upregulated during hypoxia. Here, we investigated the renoprotective effects of EPO in an IR-AKI mouse model. Mice were assigned to sham, EPO only, and IR only groups, and the IR group was treated with EPO prior to injury. EPO was administered twice at 30 min prior to bilateral renal artery occlusion, and 5 min before reperfusion, with all mice sacrificed 24 h after IR-AKI. The serum was harvested for renal functional measurements. The kidneys were subjected to histological evaluation, and the biochemical changes associated with renal injury were assessed. EPO significantly attenuated the renal dysfunction associated with IR-AKI, as well as tissue injury. Apoptotic cell death and oxidative stress were significantly reduced in EPO-treated mice. Macrophage infiltration and expression of ICAM-1 and MCP-1 were also significantly reduced in EPO-treated mice. Furthermore, the expression of inflammasome-related factors (NLRP1, NLRP3, and caspase-1 cleavage), via the activation of the COX-2 and NF-B signaling pathways were significantly reduced following EPO treatment. To our knowledge, this is the first study to demonstrate that inflammasome-mediated inflammation might be a potential target of EPO as a treatment for ischemic AKI.

Therapeutic effects of IkB kinase inhibitor during systemic inflammation

Animal models of inflammatory diseases support the idea that nuclear factor κB (NF-κB) activation plays a pathophysiological role and is widely implicated in multiple organ dysfunction (MOD). Indeed, the inhibition of the IκB kinase (IKK) complex, involved in the NF-κB pathway, can represent a promising approach to prevent MOD. The present work employed a rat model of systemic inflammation to investigate the preventive effects of Inhibitor of IKK complex (IKK16). In male Wistar rats, systemic inflammation was induced by a tail vein injection of lipopolysaccharides (LPS challenge; 12 mg/kg). Treatment with IKK16 (1 mg/kg body weight) was administered, by tail vein, 15 min post-LPS. Age- and sex-matched healthy rats and LPS rats without treatment were used as controls. At 24 h post-IKK16 treatment, serum enzyme levels indicative of liver, kidney, pancreas and muscle function were evaluated by biochemical analysis, and RT-PCR technique was used to analyze gene expression of pro-inflammatory cytokines. Hemodynamic parameters were also considered to assess the LPS-induced inflammation. IKK16 treatment yielded a strong therapeutic effect in preventing LPS-induced elevation of serological enzyme levels, attenuating hepatic, renal, pancreatic and muscular dysfunction after LPS challenge. Moreover, as expected, LPS promoted a significantly overexpression of TNF-α, IL-6 and IL-1β in the heart, kidney, and liver; which was diminished by IKK16 treatment. The present study provides convincing evidence that selective inhibition of the IκB kinase complex through the action of IKK16, plays a protective role against LPS-induced multiple organ dysfunction by reducing the acute inflammatory response induced by endotoxin exposure.

Protective effect of febuxostat in sepsis-induced liver and kidney injuries after cecal ligation and puncture with the impact of xanthine oxidase, interleukin 1β, and c-Jun N-terminal kinases

Sepsis is one of the most common causes of death among hospitalized patients. Activity of xanthine oxidase (XO), a reactive oxygen species-producing enzyme, is known to be elevated in septic patients. Our aim was to investigate the possible protective role of XO inhibitor, febuxostat (FEB), in a rat model of sepsis-induced liver and kidney injures. Adult male albino rats were divided into four groups (n = 12 each): sham control, sham + FEB, cecal ligation and puncture (CLP), and CLP + FEB groups. FEB (10 mg/kg per os (p.o.)) was given once daily for 2 days and 30 min prior to laparotomy with CLP. CLP was associated with a high mortality rate accompanied by significant liver and kidney injuries indicated by elevated serum alanine aminotransferase, aspartate aminotransferase, urea, and creatinine levels and confirmed by histopathological tissue injury. Moreover, there was an increase in neutrophil gelatinase-associated lipocalin, uric acid, malondialdehyde, and nitric oxide levels and with decreased superoxide dismutase activity and total antioxidant capacity. In addition, CLP caused increased expression of the inflammatory markers tumor necrosis factor alpha, interleukin 1beta protein levels, and nuclear factor kappa B immunoexpression. Finally, CLP operated rats exhibited an upregulation in the apoptotic mediators, caspase 3, and P-C-Jun N-terminal kinases (JNK) proteins. FEB treatment of CLP rats caused a significant improvement and normalization in all measured parameters. Moreover, FEB amerliorates degenerative histopathological changes and improves the overall survival rate. In conclusion, FEB exhibited a protective effect in sepsis-induced liver and kidney injuries most probably through its anti-inflammatory, antioxidant, and antiapoptotic properties and attenuating JNK signaling pathway secondary to its XO enzyme inhibitory activity.

Immunomodulatory role of recombinant human erythropoietin in acute kidney injury induced by crush syndrome via inhibition of the TLR4/NF-κB signaling pathway in macrophages

Objective: The present study aimed to investigate whether recombinant human erythropoietin (rHuEPO) plays an immunomodulatory function by regulating the TLR4/NF-κB signaling pathway.Materials and methods: C57BL/6 mice were intraperitoneally injected with rHuEPO and, half an hour later, with 50% glycerol at the dose of 7.5 ml/kg to induce crush syndrome (CS)-acute kidney injury (AKI). The levels of TNF-α, IL-1β, IL-6, serum creatinine (Scr), and creatine kinase (CK) were measured. The kidney tissues were analyzed by HE staining, and macrophage infiltration was detected by immunohistochemistry. Double immunofluorescence staining, RT-qPCR, and western blotting were conducted to analyze TLR4/NF-κB p65 expression. Ferrous myoglobin was co-cultured with RAW264.7 cells to mimic crush injury and the production of proinflammatory cytokines. The expression levels of TLR4 and NF-κB p65 were measured.Results: In vivo study results revealed that rHuEPO ameliorated renal function, tissue damage, production of proinflammatory cytokines, and macrophage infiltration in the kidneys. The protein and mRNA expression levels of genes involved in the TLR4/NF-κB signaling pathway in CS-induced AKI mice were upregulated (p < .05). Meanwhile, the expression levels of TLR4, NF-κB p65, and proinflammatory cytokines in RAW264.7 cells were downregulated in CS-AKI mice injected with rHuEPO (p < .05).Conclusions: Our results demonstrated the immunomodulatory capacity of rHuEPO and confirmed that rHuEPO exerts protective effects against CS-induced AKI by regulating the TLR4/NF-κB signaling pathway in macrophages. Therefore, our findings highlight the therapeutic potential of rHuEPO in improving the prognosis of CS-AKI patients.

Honokiol Attenuates Sepsis-Associated Acute Kidney Injury via the Inhibition of Oxidative Stress and Inflammation

Acute kidney injury (AKI) is one of the most common complications of sepsis, which largely contributes to the high mortality rate of sepsis. Honokiol, a natural polyphenol from the traditional Chinese herb Magnolia officinalis, is known to possess anti-inflammatory and antioxidant activity. Here, the underlying mechanism of honokiol-induced amelioration of sepsis-associated AKI was analyzed. The expression patterns of oxidative stress moleculars and TLRs-mediated inflammation pathway were examined to identify the response of NRK-52E cells incubated with septic rats' serum to honokiol. The levels of iNOS, NO, and myeloperoxidase in NRK-52E cells were increased during sepsis, which could be reversed by honokiol. The production of GSH and SOD as in vivo antioxidant was increased after honokiol treatment. The administration of honokiol significantly inhibited TLR2/4/MyD88 signaling pathway in AKI-induced NRK-52E cells. Furthermore, ZnPPIX, the HO-1 inhibitor, weakened honokiol-mediated morphological amelioration, and the reduced level of TNF-α, IL-1β, and IL-6 in kidneys of rats subjected to CLP. Finally, Honokiol was shown to connect with the Nrf2-Keap1 dimensionally. These findings suggest that honokiol plays its protective role on sepsis-associated AKI against oxidative stress and inflammatory signals.

Siwu Granules and Erythropoietin Synergistically Ameliorated Anemia in Adenine-Induced Chronic Renal Failure Rats

Objective

Renal anemia in patients with end-stage chronic kidney disease is closely related to the deterioration of cardiac function, renal function, and quality of life. This study involved adenine-induced renal anemic rat models and evaluated the treatment effect of Siwu granules and/or erythropoietin (EPO).

Methods

Fifty SD rats were randomly divided into 5 groups: control, model, Siwu, EPO, and Siwu plus EPO groups. The expression levels of NO, MDA, SOD, CAT, IL-6, TNF-α, EPO, EPOR, α-SMA, and TGF-β1 were detected in rats after 8 weeks of treatment with Siwu granules and/or EPO.

Results

After modeling, 47 rats entered the stage of treatment. Siwu plus EPO treatment significantly increased the rat hemoglobin content (p < 0.05) and reduced blood urea nitrogen (p < 0.05) and serum creatinine (p < 0.001). Compared with the control group, the expression of EPO and EPOR in the kidney of rats with renal failure was significantly decreased (p < 0.05). Moreover, the Siwu plus EPO group improved the level of oxidative stress in rats with chronic renal failure and reduced the expression of inflammatory factors. The expression of α-SMA and TGF-β1 in rats with renal failure was higher, but there was no expression in the control group.

Conclusion

Combined treatment of Siwu granules with EPO increased the expression of EPO and EPOR in the renal tissues and inhibited oxidative stress and inflammatory factors, improving the renal function and anemia.

Tocilizumab attenuates acute lung and kidney injuries and improves survival in a rat model of sepsis via down-regulation of NF-κB/JNK: a possible role of P-glycoprotein

Acute lung injury (ALI) and acute kidney injury (AKI) are major causes of sepsis-induced mortality. The objective of the study is to evaluate the effect of tocilizumab (TCZ), an IL-6 receptor inhibitor, in sepsis-induced ALI and AKI using the cecal ligation and puncture (CLP) rat model of sepsis. Clinical and experimental studies have demonstrated the importance of IL-6 in sepsis; however, the role of TCZ has not been investigated. Rats subjected to CLP developed histological evidence of ALI and AKI at 24 h. We found that TCZ alleviated sepsis-induced ALI and AKI as evidenced by improvements in various pathological changes, a significant reduction in the lung wet/dry weight ratio and total protein content in bronchoalveolar lavage fluid (BALF), and a significant decrease in the elevated serum level of creatinine (CR) and blood urea nitrogen (BUN). TCZ induced an increase in the survival rate of treated rats. Additionally, TCZ markedly inhibited sepsis-induced pulmonary and renal inflammatory responses. Moreover, we found that treatment with TCZ inhibited oxidative stress and apoptosis in lung and kidney tissue. TCZ treatment significantly inhibited NF-κB activation, attenuating JNK signaling pathway and significantly up-regulated P-glycoprotein (P-gp) expression in pulmonary as well as in renal tissues. Our data provide novel evidence that TCZ has a protective effect against sepsis-induced ALI and AKI by blocking IL-6 receptor signaling. This could provide a molecular basis for a new medical treatment for sepsis-induced ALI and AKI.

CXCL8(3-72) K11R/G31P protects against sepsis-induced acute kidney injury via NF-κB and JAK2/STAT3 pathway

Background

Acute kidney injury (AKI), which is mainly caused by sepsis, has high morbidity and mortality rates. CXCL8_(3–72) K11R/G31P (G31P) can exert therapeutic effect on inflammatory diseases and malignancies. We aimed to investigate the effect and mechanism of G31P on septic AKI.

Methods

An AKI mouse model was established, and kidney injury was assessed by histological analysis. The contents of serum creatinine (SCr) and blood urea nitrogen (BUN) were measured by commercial kits, whereas neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) were detected by enzyme-linked immunosorbent assay (ELISA) kits. The expressions of CXCL8 in serum and kidney tissues were determined using ELISA and immunohistochemical analysis, respectively. Apoptosis rate of renal tissue was detected by terminal deoxynucleotidyl transfer-mediated dUTP nick end labeling (TUNEL) analysis. The expressions of inflammatory cytokines were measured by quantitative real-time PCR and Western blot, respectively. The apoptosis-related proteins, JAK2, STAT3, NF-κB and IκB were determined by Western blot.

Results

G31P could reduce the levels of SCr, BUN, HGAL and KIM-1 and inhibit the renal tissue injury in AKI mice. G31P was also found to suppress the serum and nephric CXCL8 expressions and attenuated the apoptosis rate. The levels of inflammatory cytokines, pro-apoptotic proteins were decreased, while the anti-apoptotic proteins were increased by G31P in AKI mice. G31P also inhibited the activation of JAK2, STAT3 and NF-κB in AKI mice.

Conclusion

These results suggest that G31P could protect renal function and attenuate the septic AKI. Our findings provide a potential target for the treatment of AKI.

Dexmedetomidine ameliorates lipopolysaccharide-induced acute kidney injury in rats by inhibiting inflammation and oxidative stress via the GSK-3β/Nrf2 signaling pathway

Acute kidney injury (AKI) is a frequent and serious complication of sepsis; however, there are currently no effective therapies. Inflammation and oxidative stress are the major mechanisms implicated in lipopolysaccharide (LPS)-induced AKI. Dexmedetomidine (DEX) has been reported to have remarkable anti-inflammatory and antioxidant effects. Here, we examined the renoprotective effects of DEX and potential underlying mechanisms in rats with LPS-induced AKI. We analyzed renal function and structure; serum inflammatory cytokine; renal oxidant and antioxidant levels; and renal expression of glycogen synthase kinase-3β (GSK-3β)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway-related proteins in rats 4 hr after administration of LPS. Pretreatment with DEX improved renal function and significantly reduced the levels of inflammatory cytokines and oxidative stress markers. Treatment with DEX and the GSK-3β inhibitor SB216367 promoted phosphorylation of GSK-3β, induced Nrf2 nuclear translocation, and increased transcription of the Nrf2 target genes heme oxygenase-1 and NAD(P)H quinone oxidoreductase-1, primarily in renal tubules. Alpha-2-adrenergic receptor (α2-AR) antagonist atipamezole and imidazoline I ₂ receptor (I ₂ R) antagonist idazoxan reversed the effects of DEX. These results suggest that the renoprotective effects of DEX are mediated via α2-AR and I ₂ R-dependent pathways that reduce inflammation and oxidative stress through GSK-3β/Nrf2 signaling.

Protective Effects of Evodiamine against LPS-Induced Acute Kidney Injury through Regulation of ROS-NF-κB-Mediated Inflammation

Acute kidney injury (AKI) is a critical care syndrome, which is usually associated with sepsis-related endotoxemia. Evodiamine (EVO) is an active ingredient of many traditional medicinal formulations that possess a battery of biological activities. In the study, we aimed to evaluate the potential protective effect of EVO against lipopolysaccharide- (LPS-) induced AKI and cytotoxicity. LPS-resulted pathological injuries were significantly ameliorated by the administration of EVO. EVO reduced the levels of blood urea nitrogen (BUN) and creatinine in LPS-treated rats. EVO also inhibited LPS-induced reduction of cell viability in NRK-52E cells. LPS-resulting increase of TNFα and IL-1β in both serum and kidney of rats and NRK-52E cells was inhibited by EVO. LPS-induced increase of P65 NF-κB expression was markedly inhibited by EVO. EVO-induced reduction of TNFα and IL-1β expression in LPS-treated cells was blocked by overexpression of P65 NF-κB. Moreover, the increase of cell viability in LPS-treated cells induced by EVO was remarkably suppressed by overexpression of P65 NF-κB. LPS-resulting increase of reactive oxygen species (ROS) production was suppressed by EVO. H₂O₂ suppressed EVO-induced decrease of P65 NF-κB expression and increase of cell viability in LPS-treated NRK-52E cells. Moreover, the antioxidant NAC significantly promoted EVO-induced decrease of P65 NF-κB expression and increase of cell viability in LPS-treated NRK-52E cells. In conclusion, EVO had crucial protective effects against LPS-induced AKI and cytotoxicity through the antioxidant activities and thus the inhibition of inflammation. Our data highlight EVO as a potential candidate for the development of new strategies for the treatment of AKI.

Myocardial caspase-3 and NF-κB activation promotes calpain-induced septic apoptosis: The role of Akt/eNOS/NO pathway

AIMS

To explore the potential mechanism that the role of the Akt/eNOS/NO pathway in calpain-induced caspase-3 and NF-κB activation during septic apoptosis.

MAIN METHODS

Septic rats were stimulated by LPS (8 mg/kg, i.p.). Myocardial calpain, caspase-3, NO, TNF-α and IL-1β levels were detected by ELISA. The levels of Akt/p-Akt, eNOS/p-eNOS, iNOS proteins and number of apoptotic cells were evaluated by immunohistochemistry, western blot and TUNEL method.

KEY FINDINGS

Compared with sham, LPS treatment resulted in 4.1-fold and 1.8-fold increases in myocardial calpain activity and caspase-3 activation, respectively, and a significant increase (6.8-fold) in apoptotic cardiomyocytes was observed. The administration of calpain inhibitors (calpain inhibitor-IV, PD150606 and PD151746) showed that p-Akt and p-eNOS protein levels were correlated with the levels of LPS-induced myocardial calpain and caspase-3 activity. In addition, the quantity of p-Akt protein and NO content were markedly attenuated by wortmannin, a phosphoinositide 3-kinase (PI3K) inhibitor. Pretreatment with L-NAME, an NOS inhibitor, induced a decrease in p-eNOS proteins and apoptosis in myocardial tissues, while iNOS proteins were strongly increased in septic rats.

SIGNIFICANCE

This study suggests that the Akt/eNOS/NO pathway might lead to a novel pharmacological therapy for cardiomyocytes apoptosis in sepsis.

CIDEC Is Involved in LPS-Induced Inflammation and Apoptosis in Renal Tubular Epithelial Cells

Adenosine 5'-monophosphate-activated protein kinase (AMPK) has been shown to have anti-inflammatory effect by inhibition of the nuclear factor κB (NF-κB) pathway and is involved in lipopolysaccharide (LPS)-induced inflammation. Cell-death-inducing DFF45-like effector C (CIDEC) can directly down-regulate AMPK activity through interacting with AMPKα subunit. However, whether the AMPK or CIDEC is involved in LPS-induced inflammation in renal tubular epithelial cells is still unknown. Therefore, we studied the role of AMPK and CIDEC in LPS-treated NRK-52E cells. Our results showed that LPS could up-regulate the expression of CIDEC in vitro and in vivo. Silencing CIDEC by CIDEC-siRNA could restore expression of phosphorylated-AMPKα which was decreased by LPS, suppress LPS-induced NF-κB pathway activation, and TNF-α, IL-6, and IL-1β production in NRK-52E cells. Furthermore, silencing CIDEC also partially alleviated LPS-induced epithelial cells apoptosis. In conclusion, the results demonstrated that CIDEC/AMPK signaling pathway played an important role in LPS-induced inflammation and epithelial cells apoptosis.

β-Casomorphin-7 Ameliorates Sepsis-Induced Acute Kidney Injury by Targeting NF-κB Pathway

Background

The aim of this study was to investigate the protective effect of β-casomorphin-7 (β-CM-7) and its possible mechanisms on acute kidney injury (AKI).

Material/Methods

Rats were randomly divided into a sham group, a cecal ligation and puncture (CLP) group, and a CLP+β-CM-7 group. Kidney index, kidney function, and histopathology changes were assessed. The expression of neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (Kim-1), nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor alpha (IκBα), and p-IκBα in kidney tissues were detected by Western blotting. Inflammatory and oxidative stress factors were detected by ELISA kits.

Results

The results showed that treatment with β-CM-7 reduced the levels of creatinine (Cre), blood urea nitrogen (BUN), NGAL, and Kim-1 induced by CLP, weakening the pathological damage. In the CLP + β-CM-7 group, the tumor necrosis factor-α (TNF-α) level and the DNA-binding activity of NF-κB p65 were significantly reduced and the interleukin-10 (IL-10) level was significantly increased compared with the CLP group. b-CM-7 decreased the expression of p-IκBα/IκBα. In addition, β-CM-7 increased the activity of superoxide dismutase (SOD) and decreased the level of malondialdehyde (MDA) in kidney tissue.

Conclusions

β-CM-7 attenuated sepsis-induced AKI through reducing inflammation and oxidative stress and by inhibition of nuclear factor (NF)-κB activities. This study provides a new therapeutic agent for attenuating sepsis-induced kidney injury.

Gingerol suppresses sepsis-induced acute kidney injury by modulating methylsulfonylmethane and dimethylamine production

Acute kidney injury (AKI) and metabolic dysfunction are critical complications in sepsis syndrome; however, their pathophysiological mechanisms remain poorly understood. Therefore, we evaluated whether the pharmacological properties of 6-gingerol (6G) and 10-gingerol (10G) could modulate AKI and metabolic disruption in a rat model of sepsis (faecal peritonitis). Animals from the sham and AKI groups were intraperitoneally injected with 6G or 10G (25 mg/kg). Septic AKI decreased creatinine clearance and renal antioxidant activity, but enhanced oxidative stress and the renal mRNA levels of tumour necrosis factor-α, interleukin-1β, and transforming growth factor-β. Both phenol compounds repaired kidney function through antioxidant activity related to decreased oxidative/nitrosative stress and proinflammatory cytokines. Metabolomics analysis indicated different metabolic profiles for the sham surgery group, caecal ligation and puncture model alone group, and sepsis groups treated with gingerols. ¹H nuclear magnetic resonance analysis detected important increases in urinary creatine, allantoin, and dimethylglycine levels in septic rats. However, dimethylamine and methylsulfonylmethane metabolites were more frequently detected in septic animals treated with 6G or 10G, and were associated with increased survival of septic animals. Gingerols attenuated septic AKI by decreasing renal disturbances, oxidative stress, and inflammatory response through a mechanism possibly correlated with increased production of dimethylamine and methylsulfonylmethane.

Inhibition of endogenous hydrogen sulfide production exacerbates the inflammatory response during urine-derived sepsis-induced kidney injury

The aim of the present study was to investigate the effects of endogenous H₂S on the inflammatory response in kidneys following urine-derived sepsis-induced injury. A rabbit model of urine-derived sepsis was established by injecting Escherichia coli into the ligated ureter. Rabbits were randomly divided into the, control, sham, sepsis and DL-propargylglycine (PAG)-treated sepsis groups. The same surgical procedure except for the bacteria injection was performed for the sham group, while the control group was fed on normal diet without any additional treatments. The monitoring of vital signs, routine blood examinations and kidney function tests were performed prior to surgery and at 12, 24, 36 and 48 h following surgery. The serum H₂S concentration and kidney cystathionine-γ-lyase (CSE) activity were determined following surgery. Pathological alterations were assessed by hematoxylin and eosin (H&E) staining, and the expression levels of inflammation-associated cytokines were detected by western blot analysis. The results demonstrated that rabbits in the sepsis and PAG groups exhibited a significant increase in rectal temperature, heart rate and respiratory rate following surgery when compared with the sham group; with the PAG group demonstrating the greatest increase. In addition, white cell counts and creatinine and urea nitrogen levels were significantly elevated following surgery in the sepsis and PAG groups when compared with the sham group. The serum H₂S concentration and kidney CSE activity were significantly reduced in the sepsis group compared with the sham group, and a significant decrease in the levels of these factors were observed in the PAG group compared with the sepsis group. H&E staining indicated obvious structural abnormalities in kidney tissues in the sepsis group, which were exacerbated by PAG treatment. In addition, PAG treatment significantly increased the expression levels of nuclear factor-κB and interleukin-6, and decreased transforming growth factor-β1 expression when compared with the sepsis group. In conclusion, PAG significantly exacerbated urine-derived sepsis-induced kidney injury potentially via altering the expression of inflammation-associated cytokines.

[Predictive value of red blood cell distribution width for acute kidney injury in children with sepsis]

OBJECTIVE

To study the clinical value of red blood cell distribution width (RDW) in the early prediction of acute kidney injury (AKI) in children with sepsis.

METHODS

A total of 126 children with sepsis were divided into an AKI group (n=66) and a non-AKI group (n=60) according to the presence or absence of AKI. These patients were also classified into high-RDW and low-RDW groups according to the mean RDW. The groups were compared in terms of age, male-to-female ratio, body mass index (BMI), Acute Physiology and Chronic Health Evaluation II (APACHE II) score, Sequential Organ Failure Assessment (SOFA) score, serum blood urea nitrogen (BUN), creatinine (Cr), uric acid (UA), serum C-reactive protein (CRP), and routine blood test results. Independent factors associated with RDW were analyzed by multiple linear regression.

RESULTS

Age, male-to-female ratio, BMI, CRP, SOFA score, and APACHE II score did not differ significantly between the AKI and non-AKI groups (P>0.05), but the AKI group had significantly higher BUN, Cr, UA, and RDW levels than the non-AKI group (P<0.05). Age, male-to-female ratio, and BMI did not differ significantly between the high-RDW and low-RDW groups (P>0.05), but the high-RDW group had significantly higher BUN, Cr, UA, CRP, SOFA score, APACHE II score, Hb, and mean corpuscular volume (MCV) than the low-RDW group (P<0.05). The multiple linear regression analysis showed that age, sex, APACHE II score, Cr, Hb, and MCV were independent factors associated with RDW.

CONCLUSIONS

RDW has a certain clinical value in the early prediction of AKI in children with sepsis.

Bone mesenchymal stem cells pretreated with erythropoietin enhance the effect to ameliorate cyclosporine A-induced nephrotoxicity in rats

An increasing number of experiments and clinical trials have demonstrated the safety, feasibility, and efficacy of mesenchymal stem cells (MSCs)-based therapies for the treatment of various diseases. The main drawbacks of MSC therapy are the lack of specific homing after systemic infusion and early death of injected cells because of the injury micro-environment. We pretreated bone mesenchymal stem cells (BMSCs) with erythropoietin (EPO) to investigate their positive effect on cyclosporine A (CsA)-induced nephrotoxicity. BMSCs were incubated with different concentrations of EPO (10, 100, 500, and 1000 IU/mL) for 24 and 48 h, and their proliferation rate, cytoskeletal morphology, migration ability, and the expression of CXCR4 were evaluated to determine the optimal pretreatment conditions. To investigate the therapeutic effects of BMSCs pretreated with EPO in CsA-induced nephrotoxicity, we established CsA-induced in vitro and in vivo toxicity models. In our in vitro study, preconditioning of BMSCs with 500 IU/mL EPO for 48 h induced a marked increase in their proliferation rate, cytoskeletal rearrangement, migration in the scrape-healing assay, and migration toward injured HK2 cells. In vivo, EPO-BMSCs showed higher ability to improve renal function than BMSCs, and in CsA-induced rats treated with EPO-BMSCs, interstitial lymphocyte infiltration, tubular swelling, necrosis, and interstitial fibrosis decreased. We demonstrated that pretreatment with 500 IU/mL EPO before infusion markedly increased the homing ability of BMSCs, and obviously ameliorate CsA-induced nephrotoxicity in rats.

Oral supplementation with ursolic acid ameliorates sepsis-induced acute kidney injury in a mouse model by inhibiting oxidative stress and inflammatory responses

Ursolic acid (UA) as a multiple bioactive native compound has recently been demonstrated to treat sepsis in animal models. However, the beneficial effects of UA in sepsis‑induced acute kidney injury (AKI) are not completely understood. In the present study, the effect of UA on sepsis‑induced AKI in cecal ligation and puncture (CLP) surgery mice was investigated. Renal histomorphological analysis was performed by hematoxylin and eosin staining. The expression of inflammatory markers in the kidney of septic mice was measured by reverse transcription‑quantitative polymerase chain reaction and western blotting. The results demonstrated that UA administration improved survival in septic mice induced by CLP surgery. The treatment with UA revealed protection against AKI induced by CLP surgery, including the alleviation of glomerular damage and vacuolization in the proximal tubules. In addition, the effects of UA on oxidative stress and inflammation in septic mice were determined. The findings suggested that UA may protect against sepsis‑induced AKI by inhibiting reactive oxygen species and inflammatory cytokines, including tumor necrosis factor‑α, interleukin (IL)‑1β and IL‑6, in the kidney from septic mice. Finally, UA inhibited CLP‑induced activation of nuclear factor‑κB signaling in the kidney from septic mice. The findings of the present study demonstrated that UA may be used as a potential therapeutic agent for complications of sepsis, especially for sepsis-induced AKI.

Carbon monoxide protects the kidney through the central circadian clock and CD39

Ischemia reperfusion injury (IRI) is the predominant tissue insult associated with organ transplantation. Treatment with carbon monoxide (CO) modulates the innate immune response associated with IRI and accelerates tissue recovery. The mechanism has been primarily descriptive and ascribed to the ability of CO to influence inflammation, cell death, and repair. In a model of bilateral kidney IRI in mice, we elucidate an intricate relationship between CO and purinergic signaling involving increased CD39 ectonucleotidase expression, decreased expression of Adora1, with concomitant increased expression of Adora2a/2b. This response is linked to a >20-fold increase in expression of the circadian rhythm protein Period 2 (Per2) and a fivefold increase in serum erythropoietin (EPO), both of which contribute to abrogation of kidney IRI. CO is ineffective against IRI in Cd39^-/- and Per2^-/- mice or in the presence of a neutralizing antibody to EPO. Collectively, these data elucidate a cellular signaling mechanism whereby CO modulates purinergic responses and circadian rhythm to protect against injury. Moreover, these effects involve CD39- and adenosinergic-dependent stabilization of Per2. As CO also increases serum EPO levels in human volunteers, these findings continue to support therapeutic use of CO to treat IRI in association with organ transplantation, stroke, and myocardial infarction.

Erythropoietin mediates brain-vascular-kidney crosstalk and may be a treatment target for pulmonary and resistant essential hypertension

Organ crosstalk pathways represent the next frontier for target-mining in molecular medicine for existing syndromes. Pulmonary hypertension and resistant essential hypertension are syndromes that have been proven elusive in etiology, and frequently refractory to first-line management. Underlying crosstalk mechanisms, not yet considered in these treatments, may hinder outcomes or unlock novel treatments. This review focuses systematically on erythropoietin, a synthesizable molecule, as a mediator of brain-kidney crosstalk. Insights gained from this review will be applied to cardiovascular diseases in a clinician-directed fashion.

The macro- and microcirculation of the kidney

Acute kidney injury (AKI) remains one of the main causes of morbidity and mortality in the intensive care medicine today. Its pathophysiology and progress to chronic kidney disease is still under investigation. In addition, the lack of techniques to adequately monitor renal function and microcirculation at the bedside makes its therapeutic resolution challenging. In this article, we review current concepts related to renal hemodynamics compromise as being the event underlying AKI. In doing so, we discuss the physiology of the renal circulation and the effects of alterations in systemic hemodynamics that lead to renal injury specifically in the context of reperfusion injury and sepsis. The ultimate key culprit of AKI leading to failure is the dysfunction of the renal microcirculation. The cellular and subcellular components of the renal microcirculation are discussed and how their injury contributes to AKI is described.

Anti-Inflammatory Pyranochalcone Derivative Attenuates LPS-Induced Acute Kidney Injury via Inhibiting TLR4/NF-κB Pathway

Treatment of septic acute kidney injury (AKI) has still been beyond satisfaction, although anti-inflammatory therapy is beneficial for sepsis-induced AKI. Compound 5b was derived from natural pyranochalcones and exhibited potent anti-inflammatory activity in adjuvant-induced arthritis. In this study, we aimed to investigate the renoprotective effects and potential mechanism of 5b against lipopolysaccharide (LPS)-induced AKI. C57BL/6 mice and human renal proximal tubule cell line (HK-2 cell) were treated with LPS, respectively. Compound 5b was orally administrated at a dose of 25 mg/kg/day for 5 days before LPS (10 mg/kg) intraperitoneal injection. Cells were pretreated with 25 μg/mL 5b for 30 min before LPS (1 μg/mL) treatment. Pretreatment with 5b markedly alleviated tubular injury and renal dysfunction in LPS-induced AKI. The expression of IL-1β, IL-6, and TNF-α both in renal tissue of AKI mice and in the LPS-stimulated HK-2 cell culture medium were reduced by 5b treatment (p < 0.05). The results of immunohistochemistry staining showed that 5b reduced the expression of NF-κB p65 in kidneys. Similarly, 5b decreased the LPS-induced levels of NF-κB p65 and TLR4 proteins in kidneys and HK-2 cells. These data demonstrated that a potent pyranochalcone derivative, 5b, exhibited renoprotective effect against LPS-induced AKI, which was associated with anti-inflammatory activity by inhibiting the TLR4/NF-κB pathway.

Histopathology of Septic Acute Kidney Injury: A Systematic Review of Experimental Data

OBJECTIVE

The histopathologic changes associated with septic acute kidney injury are poorly understood, in part, because of the lack of biopsy data in humans. Animal models of septic acute kidney injury may help define such changes. Therefore, we performed a systematic review of the histopathologic changes found in modern experimental septic acute kidney injury models.

DATA SOURCES

MEDLINE, EMBASE, Cumulative Index to Nursing and Allied Health Literature, and PubMed (from January 2007 to February 2015).

STUDY SELECTION

We reviewed experimental studies reporting findings on the histopathology of contemporary experimental septic acute kidney injury.

DATA EXTRACTION

We focused on the presence or the absence of acute tubular necrosis, tubular cell apoptosis, and other nonspecific findings.

DATA SYNTHESIS

We identified 102 studies in 1,059 animals. Among the 1,059 animals, 53 (5.0%) did not have any renal histopathologic changes, but acute tubular necrosis was found in 184 (17.4%). The prevalence of acute tubular necrosis was not related to animal size or model of sepsis and was only found in models with low cardiac output and decreased renal blood flow (p < 0.0001). Only 21 studies (170 animals) assessed the prevalence of tubular cell apoptosis, which was reported in 158 animals (92.9%). The prevalence of tubular cell apoptosis was significantly higher in studies using small animals (p < 0.0001) and in peritonitis models (p < 0.0001). Simultaneous acute tubular necrosis and tubular cell apoptosis was rare (55 animals [32.4%]) and only seen with decreased cardiac output and renal blood flow. Nonspecific changes (vacuolization of tubular cells, loss of brush border, and tubular cell swelling) were each observed in 423 (39.9%), 250 (23.6%) and 243 (22.9%) animals, respectively.

CONCLUSIONS

In models of experimental septic acute kidney injury in contemporary articles, acute tubular necrosis was relatively uncommon and, when present, reflected the presence of an associated low cardiac output or low renal blood flow syndrome. Tubular cell apoptosis seemed frequent in the few studies in which it was investigated. Nonspecific morphologic changes, however, were the most common histopathologic findings.

Nerolidol Protects Against LPS-induced Acute Kidney Injury via Inhibiting TLR4/NF-κB Signaling

Acute kidney injury (AKI) is a critical care syndrome, resulting in acute reduction of renal function and up to 22% mortality of hospitalized patients. Nerolidol is a major component in several essential oils that possesses various pharmacological properties. The present study aimed to investigate the potential effect of nerolidol on lipopolysaccharide (LPS)-induced AKI. Nerolidol dose-dependently reduced the pathological injuries of kidney induced by LPS in rats. Nerolidol significantly decreased the levels of blood urea nitrogen and creatinine in LPS-treated rats in a dose-dependent manner. In addition, nerolidol inhibited LPS-induced decrease of cell viability in NRK-52E rat proximal tubular cells, which effect was concentration dependent. Nerolidol notably inhibited the increase of TNFα and IL-1β in LPS-treated rats and the mRNA expression of TNFα and IL-1β in LPS-treated NRK-52E cells. Nerolidol suppressed the increase of toll-like receptor 4 (TLR4) expression, phosphorylation and nuclear translocation of p65 NF-κB in kidneys of LPS-treated rats and LPS-treated NRK-52E cells. Overexpression of TLR4 and p65 NF-κB significantly suppressed nerolidol-induced inhibition of TNFα and IL-1β expression and increase of cell viability in LPS-treated cells. In summary, we found that nerolidol played a critical anti-inflammatory effects through inhibition of TLR4/NF-κB signaling and protected against LPS-induced AKI. Copyright © 2017 John Wiley & Sons, Ltd.

Blood transfusion improves renal oxygenation and renal function in sepsis-induced acute kidney injury in rats

Background

The effects of blood transfusion on renal microcirculation during sepsis are unknown. This study aimed to investigate the effect of blood transfusion on renal microvascular oxygenation and renal function during sepsis-induced acute kidney injury.

Methods

Twenty-seven Wistar albino rats were randomized into four groups: a sham group (n = 6), a lipopolysaccharide (LPS) group (n = 7), a LPS group that received fluid resuscitation (n = 7), and a LPS group that received blood transfusion (n = 7). The mean arterial blood pressure, renal blood flow, and renal microvascular oxygenation within the kidney cortex were recorded. Acute kidney injury was assessed using the serum creatinine levels, metabolic cost, and histopathological lesions. Nitrosative stress (expression of endothelial (eNOS) and inducible nitric oxide synthase (iNOS)) within the kidney was assessed by immunohistochemistry. Hemoglobin levels, pH, serum lactate levels, and liver enzymes were measured.

Results

Fluid resuscitation and blood transfusion both significantly improved the mean arterial pressure and renal blood flow after LPS infusion. Renal microvascular oxygenation, serum creatinine levels, and tubular damage significantly improved in the LPS group that received blood transfusion compared to the group that received fluids. Moreover, the renal expression of eNOS was markedly suppressed under endotoxin challenge. Blood transfusion, but not fluid resuscitation, was able to restore the renal expression of eNOS. However, there were no significant differences in lactic acidosis or liver function between the two groups.

Conclusions

Blood transfusion significantly improved renal function in endotoxemic rats. The specific beneficial effect of blood transfusion on the kidney could have been mediated in part by the improvements in renal microvascular oxygenation and sepsis-induced endothelial dysfunction via the restoration of eNOS expression within the kidney.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1581-1) contains supplementary material, which is available to authorized users.

Treatment With Human Wharton's Jelly-Derived Mesenchymal Stem Cells Attenuates Sepsis-Induced Kidney Injury, Liver Injury, and Endothelial Dysfunction

: The pathophysiology of sepsis involves complex cytokine and inflammatory mediator networks. Downregulation of endothelial nitric oxide synthase contributes to sepsis-induced endothelial dysfunction. Human Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) are known to reduce expression of proinflammatory cytokines and markers of apoptosis. We hypothesized that treatment with WJ-MSCs would protect renal, hepatic, and endothelial function in a cecal ligation and puncture (CLP) model of sepsis in rats. Rats were randomly divided into three groups: sham-operated rats; rats submitted to CLP and left untreated; and rats submitted to CLP and intraperitoneally injected, 6 hours later, with 1 × 10(6) WJ-MSCs. The glomerular filtration rate (GFR) was measured at 6 and 24 hours after CLP or sham surgery. All other studies were conducted at 24 hours after CLP or sham surgery. By 6 hours, GFR had decreased in the CLP rats. At 24 hours, Klotho renal expression significantly decreased. Treatment with WJ-MSCs improved the GFR; improved tubular function; decreased the CD68-positive cell count; decreased the fractional interstitial area; decreased expression of nuclear factor κB and of cytokines; increased expression of eNOS, vascular endothelial growth factor, and Klotho; attenuated renal apoptosis; ameliorated hepatic function; increased glycogen deposition in the liver; and improved survival. Sepsis-induced acute kidney injury is a state of Klotho deficiency, which WJ-MSCs can attenuate. Klotho protein expression was higher in WJ-MSCs than in human adipose-derived MSCs. Because WJ-MSCs preserve renal and hepatic function, they might play a protective role in sepsis.

SIGNIFICANCE

Sepsis is the leading cause of death in intensive care units. Although many different treatments for sepsis have been tested, sepsis-related mortality rates remain high. It was hypothesized in this study that treatment with human Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) would protect renal, hepatic, and endothelial function in a model of sepsis in rats. Treatment with WJ-MSCs improved the glomerular filtration rate, improved tubular function, decreased expression of nuclear factor κB and of cytokines, increased expression of eNOS and of Klotho, attenuated renal apoptosis, and improved survival. Sepsis-induced acute kidney injury is a state of Klotho deficiency, which WJ-MSCs can attenuate.

The neutrophil elastase inhibitor, sivelestat, attenuates sepsis-related kidney injury in rats

Sepsis-induced acute kidney injury (AKI) represents a major cause of mortality in intensive care units. Sivelestat, a selective inhibitor of neutrophil elastase (NE), can attenuate sepsis-related acute lung injury. However, whether sivelestat can preserve kidney function during sepsis remains unclear. In this study, we thus examined the effects of sivelestat on sepsis-related AKI. Cecal ligation and puncture (CLP) was performed to induce multiple bacterial infection in male Sprague-Dawley rats, and subsequently, 50 or 100 mg/kg sivelestat were administered by intraperitoneal injection immediately after the surgical procedure. In the untreated rats with sepsis, the mean arterial pressure (MAP) and glomerular filtration rate (GFR) were decreased, whereas serum blood urea nitrogen (BUN) and neutrophil gelatinase-associated lipocalin (NGAL) levels were increased. We found that sivelestat promoted the survival of the rats with sepsis, restored the impairment of MAP and GFR, and inhibited the increased BUN and NGAL levels; specifically, the higher dose was more effective. In addition, sivelestat suppressed the CLP-induced macrophage infiltration, the overproduction of pro-inflammatory mediators (tumor necrosis factor-α, interleukin-1β, high-mobility group box 1 and inducible nitric oxide synthase) and serine/threonine kinase (Akt) pathway activation in the rats. Collectively, our data suggest that the inhibition of NE activity with the inhibitor, sivelestat, is beneficial in ameliorating sepsis-related kidney injury.

Metabolic acidosis aggravates experimental acute kidney injury

AIMS

Ischemia/reperfusion (I/R) injury and metabolic acidosis (MA) are two critical conditions that may simultaneously occur in clinical practice. The result of this combination can be harmful to the kidneys, but this issue has not been thoroughly investigated. The present study evaluated the influence of low systemic pH on various parameters of kidney function in rats that were subjected to an experimental model of renal I/R injury.

MAIN METHODS

Metabolic acidosis was induced in male Wistar rats by ingesting ammonium chloride (NH4Cl) in tap water, beginning 2 days before ischemic insult and maintained during the entire study. Ischemia/reperfusion was induced by clamping both renal arteries for 45 min, followed by 48 h of reperfusion. Four groups were studied: control (subjected to sham surgery, n=8), I/R (n=8), metabolic acidosis (MA; 0.28 M NH4Cl solution and sham surgery, n=6), and MA+I/R (0.28 M NH4Cl solution plus I/R, n=9).

KEY FINDINGS

Compared with I/R rats, MA+I/R rats exhibited higher mortality (50 vs. 11%, p=0.03), significant reductions of blood pH, plasma bicarbonate (pBic), and standard base excess (SBE), with a severe decline in the glomerular filtration rate and tubular function. Microscopic tubular injury signals were detected. Immunofluorescence revealed that the combination of MA and I/R markedly increased nuclear factor κB (NF-κB) and heme-oxygenase 1 (HO-1), but it did not interfere with the decrease in endothelial nitric oxide synthase (eNOS) expression that was caused by I/R injury.

SIGNIFICANCE

Acute ischemic kidney injury is exacerbated by acidic conditions.

Bridging Translation by Improving Preclinical Study Design in AKI

Despite extensive research, no therapeutic interventions have been shown to prevent AKI, accelerate recovery of AKI, or reduce progression of AKI to CKD in patients. This failure in translation has led investigators to speculate that the animal models being used do not predict therapeutic responses in humans. Although this issue continues to be debated, an important concern that has not been addressed is whether improvements in preclinical study design can be identified that might also increase the likelihood of translating basic AKI research into clinical practice using the current models. In this review, we have taken an evidence-based approach to identify common weaknesses in study design and reporting in preclinical AKI research that may contribute to the poor translatability of the findings. We focused on use of N-acetylcysteine or sodium bicarbonate for the prevention of contrast-induced AKI and use of erythropoietin for the prevention of AKI, two therapeutic approaches that have been extensively studied in clinical trials. On the basis of our findings, we identified five areas for improvement in preclinical study design and reporting. These suggested and preliminary guidelines may help improve the quality of preclinical research for AKI drug development.

Associations between single nucleotide polymorphisms in the FAS pathway and acute kidney injury

Introduction

To determine whether single nucleotide polymorphisms (SNPs) in FAS and related genes are associated with acute kidney injury (AKI) in patients with acute respiratory distress syndrome (ARDS).

Methods

We studied 401 (Caucasian N = 310 and African-American N = 91) patients aged ≥ 13 years with ALI who enrolled in the Fluid and Catheter Treatment Trial (FACTT) between 2000 and 2005 from 20 North American centers. We genotyped 367 SNPs in 45 genes of the Fas/Fas ligand pathway to identify associations between SNPs in Fas pathway genes and the development of AKI by day 2 after enrollment in FACTT, adapting Acute Kidney Injury Network (AKIN) criteria. Written informed consent was obtained from participants or legally authorized surrogates in the original FACTT study and available to use for secondary analysis.

Results

In Caucasian patients, we identified associations between two SNPs and the incidence of AKI (stage 1 and above): rs1050851 and rs2233417; both are found within the gene for nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (NFKBIA). For rs1050851 and rs2233417, the odds ratios (ORs) were 2.34 (95 % confidence interval (CI) = 1.58–3.46, p = 1.06 × 10⁻⁵, FDR = 0.003) and 2.46 (CI = 1.61–3.76, p = 1.81 × 10⁻⁵, FDR = 0.003) for each minor allele, respectively. The associations were stronger still for AKIN stage 2–3 with respective ORs 4.00 (CI = 2.10–7.62, p = 1.05 × 10⁻⁵, FDR = 0.003) and 4.03 (CI = 2.09–7.77, p = 1.88 × 10⁻⁵, FDR = 0.003) for each minor allele homozygote. We observed no significant association between these SNPs and AKI in the smaller subset of African Americans.

Conclusion

In Caucasian patients with ALI, the presence of minor alleles in two SNPs in NFKBIA was strongly associated with the development of AKI.

Trial registration

NCT00281268. Registered 20/01/2006.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-1084-5) contains supplementary material, which is available to authorized users.

Epoetin beta pegol prevents endothelial dysfunction as evaluated by flow-mediated dilation in chronic kidney disease rats

Chronic kidney disease (CKD) patients have a poor prognosis due to cardiovascular disease. Anemia and endothelial dysfunction are important risk factors for cardiovascular events in CKD patients, and treatment with erythropoiesis-stimulating agent (ESA) has been reported to improve the quality of life in CKD patients. In this study, we evaluated the effect of anemia correcting dose of epoetin beta pegol (continuous erythropoietin receptor activator; C.E.R.A.) on endothelial function in 5/6 nephrectomized rats (Nx rats). C.E.R.A. was subcutaneously administered once a fortnight, 5 times in total, from 1 week after nephrectomy. Twenty-four hours after last administration, endothelial function was evaluated by measuring flow-mediated dilation (FMD) in the femoral arteries of anesthetized Nx rats by ultrasound system. Femoral arteries were harvested for western blot analysis. C.E.R.A. significantly increased FMD of Nx rats. Endothelium-independent vasodilation induced by nitroglycerin injection was not influenced by C.E.R.A treatment. Nox4 expression and nitrotyrosine accumulation were significantly decreased, and phosphorylation of eNOS was significantly enhanced in the femoral arteries of C.E.R.A.-treated rats. C.E.R.A. normalized hemoglobin levels but did not affect body weight, systolic blood pressure, heart rate, urinary protein excretion and plasma creatinine. These results indicate that C.E.R.A. prevented endothelial dysfunction in Nx rats, possibly through reduction of local oxidative stress and enhancement of eNOS phosphorylation in the arteries. This study provides the first evidence that C.E.R.A. prevented endothelial dysfunction in CKD model rats under conditions of amelioration of anemia.