Acute renal failure in endotoxemia is caused by TNF acting directly on TNF receptor-1 in kidney

Ethanol Extract of Illicium henryi Attenuates LPS-Induced Acute Kidney Injury in Mice via Regulating Inflammation and Oxidative Stress

The root bark of Illicium henryi has been used in traditional Chinese medicine to treat various diseases. Its ethanol extract (EEIH) was found to contain a large number of phenols and possess in vitro antioxidant activities. The present study aimed to investigate its protective effect against lipopolysaccharide (LPS)-induced acute kidney injury (AKI) in mice. BALB/c mice were intraperitoneally pretreated with EEIH for five days, and then LPS injection was applied to induce AKI. Blood samples and kidney tissues were collected and used for histopathology, biochemical assay, enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qRT-PCR), and Western blot analyses. EEIH not only significantly dose-dependently attenuated histological damage and reduced renal myeloperoxidase (MPO) activity (from 9.77 ± 0.73 to 0.84 ± 0.30 U/g tissue) but also decreased serum creatinine (from 55.60 ± 2.70 to 27.20 ± 2.39 µmol/L) and blood urea nitrogen (BUN) (from 29.95 ± 1.96 to 16.12 ± 1.24 mmol/L) levels in LPS-treated mice. EEIH also markedly dose-dependently inhibited mRNA expression and production of TNF-α (from 140.40 ± 5.15 to 84.74 ± 5.65 pg/mg), IL-1β (from 135.54 ± 8.20 to 77.15 ± 5.34 pg/mg), IL-6 (from 168.74 ± 7.23 to 119.16 ± 9.35 pg/mg), and COX-2 in renal tissue of LPS-treated mice via downregulating mRNA and protein expressions of toll-like receptor 4 (TLR4) and phosphorylation of nuclear factor-κB (NF-κB) p65. Moreover, EEIH significantly dose-dependently reduced malondialdehyde (MDA) (from 5.43 ± 0.43 to 2.80 ± 0.25 nmol/mg prot) and NO (from 1.01 ± 0.05 to 0.24 ± 0.05 µmol/g prot) levels and increased superoxide dismutase (SOD) (from 22.32 ± 2.92 to 47.59 ± 3.79 U/mg prot) and glutathione (GSH) (from 6.57 ± 0.53 to 16.89 ± 0.68 µmol/g prot) levels in renal tissue induced by LPS through upregulating mRNA expression of nuclear factor erythroid 2 related factor 2 (Nrf2). Furthermore, EEIH inhibited LPS-induced intracellular reactive oxygen species (ROS) production from RAW264.7 cells in a concentration-dependent manner. These results suggest that EEIH has protective effects against AKI in mice through regulating inflammation and oxidative stress.

Protective Role of Hepcidin in Polymicrobial Sepsis and Acute Kidney Injury

Background: Acute kidney injury (AKI) portends worse prognosis following sepsis, with limited available interventions. Host iron acquisition by pathogens and systemic inflammatory response are key events in the pathogenesis of sepsis. In sepsis, hepcidin induces iron sequestration to limit iron availability to pathogens. Hepcidin is also known to limit inflammation. Since its role in pathophysiology of sepsis-associated AKI is unknown, we investigated the effect of exogenous hepcidin in endotoxin- and peritonitis-induced pathology and AKI.

Methods: C57BL/6 mice were treated with saline or 50–100 µg of hepcidin, pre- and post-LPS injection, or cecal ligation and puncture (CLP, model of peritonitis). Splenectomized mice were challenged with LPS, with and without hepcidin. Mice were euthanized at 24 h after LPS injection and at different time points after CLP. Systemic inflammation and renal injury markers were assessed. Direct effect of hepcidin on renal tubular and endothelial cells was evaluated using endotoxin-induced cytotoxic serum. Role of heavy chain ferritin (H-ferritin) in mediating hepcidin-induced anti-inflammatory effect on LPS stimulated macrophages was evaluated with siRNA studies.

Results: Twenty-four hours pretreatment with hepcidin significantly reduced LPS-induced AKI. Hepcidin ameliorated LPS-induced increase in serum TNFα and renal Cox-2, and prevented loss in PGC1α and cytochrome c oxidase activity. This was associated with reduced glomerular injury and preserved mitochondrial structure. Hepcidin did not exert direct protection on the renal parenchymal cells but reduced endotoxin-induced serum cytotoxicity to mitigate renal injury. Splenectomy reduced LPS-induced early inflammation and AKI, independent of hepcidin, indicating the importance of systemic inflammation. Higher splenic H-ferritin in hepcidin-treated animals was associated with reduced splenocytes apoptosis and inflammation. Hepcidin reduced LPS-induced IL-6 secretion in macrophages in H-ferritin dependent manner. Hepcidin significantly reduced CLP-induced AKI, and mortality (20% hepcidin treated vs 80% PBS treated). Importantly hepcidin reduced bacteremia and AKI even when administered after onset of sepsis.

Conclusion: We demonstrate a protective role of hepcidin in endotoxin- and peritonitis-induced pathologies and AKI, exerted primarily through its anti-inflammatory effects, and antibacterial property. Macrophage H-ferritin plays an important role in hepcidin-mediated protection against endotoxin-induced inflammation. We uncover a novel prophylactic and therapeutic role of hepcidin in sepsis-associated bacteremia, AKI, and mortality.

Prevention of lipopolysaccharide-induced CD11b+ immune cell infiltration in the kidney: role of AT2 receptors

Immune cell infiltration plays a central role in mediating endotoxemic acute kidney injury (AKI). Recently, we have reported the anti-inflammatory and reno-protective role of angiotensin-II type-2 receptor (AT₂R) activation under chronic low-grade inflammatory condition in the obese Zucker rat model. However, the role of AT₂R activation in preventing lipopolysaccharide (LPS)-induced early infiltration of immune cells, inflammation and AKI is not known. Mice were treated with AT₂R agonist C21 (0.3 mg/kg), with and without AT₂R antagonist PD123319 (5 mg/kg) prior to or concurrently with LPS (5 mg/kg) challenge. Prior-treatment with C21, but not concurrent treatment, significantly prevented the LPS-induced renal infiltration of CD11b⁺ immune cells, increase in the levels of circulating and/or renal chemotactic cytokines, particularly interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1) and markers of renal dysfunction (blood urea nitrogen and albuminuria), while preserving anti-inflammatory interleukin-10 (IL-10) production. Moreover, C21 treatment in the absence of LPS increased renal and circulating IL-10 levels. To investigate the role of IL-10 in a cross-talk between epithelial cells and monocytes, we performed in vitro conditioned media (CM) studies in human kidney proximal tubular epithelial (HK-2) cells and macrophages (differentiated human monocytes, THP-1 cells). These studies revealed that the conditioned-media derived from the C21-treated HK-2 cells reduced LPS-induced THP-1 tumor necrosis factor-α (TNF-α) production via IL-10 originating from HK-2 cells. Our findings suggest that prior activation of AT₂R is prophylactic in preventing LPS-induced renal immune cell infiltration and dysfunction, possibly via IL-10 pathway.

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.

Procalcitonin and Liver Disease: A Literature Review

Procalcitonin (PCT) is a widely used biomarker for the diagnosis of bacterial infections. It is produced by various organs and the liver is considered to be the most important site of production. Severe liver dysfunction has been shown to influence PCT levels. Patients with no sources of infection who have liver disease are observed to have increased serum levels of PCT, thereby reducing the diagnostic utility and value within this particular patient subset. Here, we have summarized the relationship between PCT and liver disease, including liver cirrhosis, liver failure, and liver transplantation.

Endotoxin modulates the electrophysiological characteristics of human embryonic stem cell‐differentiated cardiomyocytes

Gram‐negative bacteria‐induced infections result in fever, arrhythmia, and even death. Lipopolysaccharide (LPS), a constituent of bacteria, leads to an inflammatory response under sepsis and increase arrhythmogenesis. This study analyzed the effects on human embryonic stem cell‐differentiated cardiomyocytes (HIPSC‐CMs) exposed to LPS. A whole cell patch clamp was used to record the action potential (AP) and ionic currents with or without different doses of LPS in HIPSC‐CMs. Compared with the control, a different dose (0.04, 0.2, 1, and 5 µg/ml) of LPS‐treated HIPSC‐CMs resulted in a longer AP duration. The IC50 of sodium channel current was 1.254 µg/ml, L‐type calcium channel current was 5 µg/ml, and I_k channel currents were 1.254 µg/ml. LPS‐treated HIPSC‐CMs showed a lower sodium channel current, L‐type calcium channel current, and I_k channel currents. Furthermore, the expressions of Nav1.5 were decreased, and L‐Ca, Kv11.1, and Kv7.1 were increased in LPS‐treated HIPSC‐CMs. LPS‐induced arrhythmogenesis was related to the electrophysiological characteristics of sodium channel current, L‐type calcium channel current, and I_k channel currents. These results suggest a potential mechanism of cardiomyocyte injury in endotoxemia.

Proteomics and Metabolomics for AKI Diagnosis

Acute kidney injury (AKI) is a severe and frequent condition in hospitalized patients. Currently, no efficient therapy of AKI is available. Therefore, efforts focus on early prevention and potentially early initiation of renal replacement therapy to improve the outcome in AKI. The detection of AKI in hospitalized patients implies the need for early, accurate, robust, and easily accessible biomarkers of AKI evolution and outcome prediction because only a narrow window exists to implement the earlier-described measures. Even more challenging is the multifactorial origin of AKI and the fact that the changes of molecular expression induced by AKI are difficult to distinguish from those of the diseases associated or causing AKI as shock or sepsis. During the past decade, a considerable number of protein biomarkers for AKI have been described and we expect from recent advances in the field of omics technologies that this number will increase further in the future and be extended to other sorts of biomolecules, such as RNAs, lipids, and metabolites. However, most of these biomarkers are poorly defined by their AKI-associated molecular context. In this review, we describe the state-of-the-art tissue and biofluid proteomic and metabolomic technologies and new bioinformatics approaches for proteomic and metabolomic pathway and molecular interaction analysis. In the second part of the review, we focus on AKI-associated proteomic and metabolomic biomarkers and briefly outline their pathophysiological context in AKI.

Kidney Injury Biomarkers in an Academic Hospital Setting: Where Are We Now?

Acute kidney injury (AKI) is a frequent complication in hospitalised patients and is diagnosed by urinary output and serum creatinine. Serum creatinine is an indirect marker for renal glomerular filtration, but lacks specificity for damage to kidney tissue and the relatively late response to injury precludes early recognition of AKI. Timely diagnosis of kidney injury using biomarkers that provide information about the aetiology of kidney injury is an unmet clinical need. To overcome the suboptimal performance of serum creatinine, injury biomarkers have been proposed that predict AKI in diverse clinical settings. The clinical performance of these markers is considered moderate due to the lack of specificity for kidney tissue or the underlying injury mechanisms, poor test specificity and confounding by interventions or comorbidities. Hence, it is not unequivocally beneficial to implement current kidney injury biomarkers in the clinical laboratory for diagnostic purposes. In this article we review biomarkers that might fulfil AKI-related unmet clinical needs in the academic hospital setting.

Talin1 Methylation Is Required for Neutrophil Infiltration and Lipopolysaccharide-Induced Lethality

Talin1, a well-established integrin coactivator, is critical for the transmigration of neutrophils across the vascular endothelium into various organs and the peritoneal cavity during inflammation. Several posttranslational modifications of talin1 have been proposed to play a role in this process. In this study, we show that trimethylation of talin1 at Lys2454 by cytosolic Ezh2 is substantially increased in murine peritoneal neutrophils upon induction of peritonitis. By reconstituting talin1-deficient mouse myeloid cells with wild-type, methyl-mimicking, or unmethylatable talin1 variants, we demonstrate that methylation of talin1 at Lys2454 is important for integrin-dependent neutrophil infiltration into the peritoneal cavity. Furthermore, we show that treatment with an Ezh2 inhibitor or reconstitution of talin1-deficient myeloid cells with unmethylatable talin1 significantly reduces the number of organ-infiltrating neutrophils and protects mice from LPS-induced mortality.

P53 in kidney injury and repair: Mechanism and therapeutic potentials

Acute kidney injury (AKI) is a major kidney disease with poor clinical outcome. Besides its acute consequence of high mortality, AKI may also contribute significantly to the occurrence and progression of chronic kidney diseases (CKD). Accumulating evidence has demonstrated that maladaptive and incomplete kidney repair after AKI leads to the development of renal fibrosis and, ultimately, CKD. p53, a well-known tumor suppressor, plays a critical role in AKI and subsequent kidney repair through the regulation of various cell biologic processes, including apoptosis, cell cycle arrest, and autophagy. Despite the notable progress in deciphering the involvement of p53 in kidney injury and repair, the underlying mechanisms of p53 in these pathological processes remain largely unknown. Further investigation in this area is essential for the application of p53 as therapeutic target to prevent and treat AKI or impede its progression to CKD. In this review, we summarize the recent advances in understanding p53 regulation of AKI and kidney repair, pinpoint the potential of p53 as a therapeutic target, and present future research interests and directions.

Association of Soluble TNFR-1 Concentrations with Long-Term Decline in Kidney Function: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND

TNF receptor-1 (TNFR-1), which plays a causative role in endothelial cell dysfunction and inflammation, is expressed on the cell surface in glomerular and peritubular capillary endothelium of the kidneys. Higher soluble TNF receptor-1 (sTNFR-1) concentrations are associated with kidney disease progression among persons with established diabetic kidney disease. However, no studies have assessed sTNFR-1's role in long-term kidney function changes in a multiethnic population without cardiovascular disease at baseline.

METHODS

We tested associations between baseline sTNFR-1 concentrations and 10-year decline in eGFR (incident ≥40% decline and annual proportional decline) among 2548 participants in the Multi-Ethnic Study of Atherosclerosis (MESA), a prospective cohort study. Serum creatinine concentrations were determined at enrollment and study years 3, 5, and 10.

RESULTS

Mean age of participants was 61 years old, 53% were women, and mean baseline eGFR was 79 ml/min per 1.73 m². Serum sTNFR-1 was inversely associated with baseline eGFR. Over median follow-up of 9.3 years, 110 participants developed ≥40% decline in eGFR; each SD higher concentration of sTNFR1 was associated with higher risk of 40% eGFR decline (adjusted hazard ratio, 1.43; 95% confidence interval [95% CI], 1.16 to 1.77; P<0.001). The highest sTNFR-1 tertile was associated with adjusted annualized decline in eGFR of 1.94% (95% CI, 1.79 to 2.09). Associations persisted across subgroups defined by demographics, hypertension, diabetes, and baseline CKD status.

CONCLUSIONS

Elevated serum sTNFR-1 concentrations are associated with faster declines in eGFR over the course of a decade in a multiethnic population, independent of previously known risk factors for kidney disease progression.

Acute stimulatory effect of tumor necrosis factor on the basolateral 50 pS K channels in the thick ascending limb of the rat kidney

The aim of the present study was to investigate the acute effect and mechanism of tumor necrosis factor (TNF) on basolateral 50 pS K channels in the thick ascending limb (TAL) of the rat kidney. The TAL tubules were isolated from the rat kidney, and the activity of the 50 pS K channels was recorded using the patch‑clamp technique. The results indicated that the application of TNF (10 nM) significantly activated the 50 pS K channels and the TNF effect was concentration‑dependent. Inhibition of protein kinase A, phospholipase A2 and protein tyrosine kinase using pathway inhibitors (H89, AACOCF3 and Herbimycin A, respectively) did not abolish the stimulatory effect of TNF, indicating that none of these pathways mediated the TNF effect. By contrast, the phenylarsine oxide inhibitor against protein tyrosine phosphatase (PTP) decreased the activity of the 50 pS K channels and blocked the stimulatory effect of TNF on these channels. Furthermore, western blot analysis demonstrated that the application of TNF (10 nM) in the TAL increased the phosphorylation of PTP, an indication of PTP activity stimulation. Thus, it was concluded that the acute application of TNF may stimulate the basolateral 50 pS K channel in the TAL and the stimulatory effect of TNF may be mediated by the PTP‑dependent pathway.

Farnesoid X receptor agonist obeticholic acid inhibits renal inflammation and oxidative stress during lipopolysaccharide-induced acute kidney injury

It is increasingly recognized that farnesoid X receptor (FXR) has anti-inflammatory and antioxidant activities. The present study investigated the effects of obeticholic acid (OCA), a novel synthetic FXR agonist, on renal inflammation and oxidative stress in a model of sepsis-induced acute kidney injury. All mice except controls were intraperitoneally injected with lipopolysaccharide (LPS, 2.0 mg/kg). In the OCA + LPS group, mice were orally pretreated with three doses of OCA (5 mg/kg) at 48, 24 and 1 h before LPS injection. Interestingly, OCA pretreatment alleviated LPS-induced renal dysfunction and pathological damage. Moreover, OCA pretreatment repressed renal inflammatory cytokines and chemokines during LPS-induced acute kidney injury. In addition, OCA blocked nuclear translocation of nuclear factor kappa B (NF-κB) p65 and p50 subunits in tubular epithelial cells of renal cortex. Additional experiment showed that OCA pretreatment attenuated LPS-induced renal glutathione depletion, lipid peroxidation and protein nitration. Moreover, OCA pretreatment inhibited the upregulation of renal NADPH oxidase and inos genes during LPS-induced acute kidney injury. In conclusion, OCA pretreatment protects against sepsis-induced acute kidney injury through inhibiting renal inflammation and oxidative stress. These results provide evidence for roles of FXR as an important regulator of inflammation and oxidative stress in the kidney.

NGAL protects against endotoxin-induced renal tubular cell damage by suppressing apoptosis

Background

We sought to confirm that neutrophil gelatinase-associated lipocalin (NGAL) protects against apoptosis during endotoxemia.

Methods

Endotoxemia was induced in rats with lipopolysaccharide (LPS; 3.5 mg/kg) and serum creatinine (SCr), urinary NGAL (uNGAL), renal histopathology confirmed acute kidney injury (AKI). Renal caspase 3 and NGAL were assayed with immunohistochemistry 6 h later. A HK-2 cell model was used in which NGAL and caspase 3 mRNA were evaluated by qRT-PCR within 6 h after LPS (50 μM) treatment, and correlations were studied. NGAL and caspase 3 mRNA expression were measured after delivering NGAL siRNA in HK-2 cells and apoptosis was measured with TUNEL and flow cytometry.

Results

SCr and uNGAL were significantly increased after LPS treatment and renal morphology data indicated AKI and renal tubular epithelial cell apoptosis. Caspase 3 and NGAL were predominantly expressed in the tubular epithelial cells and there was a correlation between caspase 3 and NGAL protein (r = 0.663, p = 0.01). In vitro, there was a strong correlation between caspase 3 and NGAL mRNA in LPS-injured HK-2 cells within 24 h (r = 0.448, p < 0.05). Suppressing the NGAL gene in HK-2 cells increased caspase 3 mRNA 4.5-fold and apoptosis increased 1.5-fold after LPS treatment.

Conclusions

NGAL is associated with caspase 3 in renal tubular cells with endotoxin-induced kidney injury, and may regulate its expression and inhibit apoptosis.

Bacteriolysis - a mere laboratory curiosity?

The role of bacteriolysis in the pathophysiology of microbial infections dates back to 1893 when Buchner and Pfeiffer reported for the first time the lysis of bacteria by immune serum and related this phenomenon to the immune response. Later on, basic anti-microbial peptides and certain beta-lactam antibiotics have been shown not only to kill microorganisms but also to induce bacteriolysis and the release of cell-wall components. In 2009, a novel paradigm was offered suggesting that the main cause of death in sepsis is due to the exclusive release from activated human phagocytic neutrophils (PMNs) traps adhering upon endothelial cells of highly toxic nuclear histone. Since activated PMNs also release a plethora of pro-inflammatory agonists, it stands to reason that these may act in synergy with histone to damage cells. Since certain beta lactam antibiotics may induce bacteriolysis, it is questioned whether these may aggravate sepsis patient's condition. Enigmatically, since the term bacteriolysis and its possible involvement in sepsis is hardly ever mentioned in the extensive clinical articles and reviews dealing with critical care, we hereby aim to refresh the concept of bacteriolysis and its possible role in the pathogenesis of post infectious sequelae.

Independent risk factors for postoperative AKI and the impact of the AKI on 30-day postoperative outcomes in patients with type A acute aortic dissection: an updated meta-analysis and meta-regression

Background

This meta-analysis aims to investigate the effects of postoperative acute kidney injury (AKI) on 30-day postoperative outcomes and the independent risk factors for postoperative AKI in patients with type A acute aortic dissection (TAAD).

Methods

Relevant reports published between January 1, 2011 and May 31, 2017 were searched in multiple electronic literature databases. A total of seven eligible articles were included in the meta-analysis.

Results

Postoperative AKI was associated with 249% increase in 30-day postoperative mortality [odds ratio (OR): 3.49; 95% confidence interval (CI): 2.17-5.59; P<0.0001]. Subgroup analysis revealed that patients with stage II/III AKI showed 445% increase in 30-day postoperative mortality compared with the control group (OR: 5.45; 95% CI: 2.87-10.36; P<0.0001). Postoperative AKI was also associated with 143%, 432%, and 126% increase in the incidences of 30-day postoperative stroke, bleeding, and respiratory complications, respectively. Notably, high body mass index (BMI), advanced age, and perioperative sepsis were independent risk factors for postoperative AKI in patients with TAAD.

Conclusions

This meta-analysis firstly provided clinical evidence showing the adverse effects of postoperative AKI on 30-day postoperative outcomes in patients with TAAD and identified high BMI, advanced age, and perioperative sepsis as the independent risk factors for postoperative AKI. These findings suggest that preventive or therapeutic methods to effectively manage postoperative AKI may improve 30-day postoperative outcomes in patients with TAAD.

The Nephroprotective Effect of MS-275 on Lipopolysaccharide (LPS)-Induced Acute Kidney Injury by Inhibiting Reactive Oxygen Species (ROS)-Oxidative Stress and Endoplasmic Reticulum Stress

Background

Histone deacetylase (HDAC) inhibitors can attenuate acute kidney injury (AKI)-mediated damage and reduce fibrosis in kidney disease models. The aim of the present study was to investigate the effects of the HDAC inhibitor MS-275 on lipopolysaccharide (LPS)-induced AKI and the associated mechanisms.

Material/Methods

A LPS-induced model in 6–8 weeks-old mice was established by intraperitoneal injection of LPS (10 mg/kg), with pre-treatment of MS-275 (2 mg/kg/day) administered intraperitoneally for five days. In addition, HK-2 cells were exposed to LPS (1 μg/mL) at 0.1 nM, 1 nM, 10 nM, and 100 nM. For our in vitro MS-275 study, detection programs included histology, biochemical, immunohistochemistry, mRNA and protein expression as well as apoptosis.

Results

MS-275 ameliorated renal damage, enhanced the survival rate of the LPS-induced sepsis model, decreased the expressions of TNF-α, IL-1β, IL-6, COX-2, and NF-κBp65 nucleus translocation, suppressed the HDAC activity which was enhanced in septic AKI mice, and enhanced the acetylation of histone H3 and H4. Reactive oxygen species (ROS) production was enhanced in the kidney of LPS mice compared to control mice, while MS-275 suppressed the production of ROS in kidney tissue. In the in vitro studies, MS-275 reduced the LPS-induced apoptosis of HK-2 cells, inhibited ROS and MDA production, increased the production GSH and SOD activity, decreased the expressions of CHOP, GRP78, caspase3, and capase12, which was related to endoplasmic reticulum stress in LPS stimulated HK-2 cells.

Conclusions

MS-275 pre-treatment improved renal function and ameliorated histological alterations, inflammation, and ROS production in LPS-induced AKI mice and may act through inhibiting ROS-oxidative stress and endoplasmic reticulum stress.

Nitrolipids in kidney physiology and disease

The kidneys are vital organs responsible for maintaining body fluid homeostasis within proper physiologic ranges. Kidney disease is an epidemic clinical problem causing significant morbidity and mortality, and current treatments are limited to renin-angiotensin system blockade or renal replacement therapy for the majority of affected individuals. There is a critical, unmet need for novel pharmacological agents to improve the outcome of patients with kidney disease. Nitro-oleic acid (NO2-OA) is an endogenously generated electrophilic compound with the capacity to modify thiols in proteins, altering their function. The most important targets appear to be the Keap1/Nrf2 and NF-κB pathways, which have widespread effects on antioxidant, detoxifying, and inflammatory responses in cells and tissues. Through these and potentially additional protective actions, NO2-OA may be capable of preserving or enhancing kidney function in acute and chronic kidney diseases.

Resveratrol protects against early polymicrobial sepsis-induced acute kidney injury through inhibiting endoplasmic reticulum stress-activated NF-κB pathway

Resveratrol, a polyphenol compound derived from various edible plants, protects against sepsis-induced acute kidney injury (AKI) via its anti-inflammatory activity, but the underlying mechanisms remain largely unknown. In this study, a rat model of sepsis was established by cecal ligation and puncture (CLP), 30 mg/kg resveratrol was intraperitoneally administrated immediately after the CLP operation. HK-2 cells treated by 1 μg/ml lipopolysaccharide, 0.2 μM tunicamycin, 2.5 mM irestatin 9389 and 20 μM resveratrol were used for in vitro study. The results demonstrated that resveratrol significantly improved the renal function and tubular epithelial cell injury and enhanced the survival rate of CLP-induced rat model of sepsis, which was accompanied by a substantial decrease of the serum content and renal mRNA expressions of TNF-α, IL-1β and IL-6. In addition, resveratrol obviously relieved the endoplasmic reticulum stress, inhibited the phosphorylation of inositol-requiring enzyme 1(IRE1) and nuclear factor-κB (NF-κB) in the kidney. In vitro studies showed that resveratrol enhanced the cell viability, reduced the phosphorylation of NF-κB and production of inflammatory factors in lipopolysaccharide and tunicamycin-induced HK-2 cells through inhibiting IRE1 activation. Taken together, administration of resveratrol as soon as possible after the onset of sepsis could protect against septic AKI mainly through inhibiting IRE1-NF-κB pathway-triggered inflammatory response in the kidney. Resveratrol might be a readily translatable option to improve the prognosis of sepsis.

Hyperin protects against LPS-induced acute kidney injury by inhibiting TLR4 and NLRP3 signaling pathways

Hyperin is a flavonoid compound derived from Ericaceae, Guttifera, and Celastraceae that has been shown to have various biological effects, such as anti-inflammatory and anti-oxidant effects. However, there is no evidence to show the protective effects of hyperin on lipopolysaccharide (LPS)-induced acute kidney injury (AKI). Therefore, we investigated the protective effects and mechanism of hyperin on LPS-induced AKI in mice. The levels of TNF-α, IL-6, and IL-1β were tested by ELISA. The effects of hyperin on blood urea nitrogen (BUN) and serum creatinine were also detected. In addition, the expression of TLR4, NF-κB, and NLRP3 were detected by western blot analysis. The results showed that hyperin significantly inhibited LPS-induced TNF-α, IL-6, and IL-1β production. The levels of BUN and creatinine were also suppressed by hyperin. Furthermore, LPS-induced TLR4 expression and NF-κB activation were also inhibited by hyperin. In addition, treatment of hyperin dose-dependently inhibited LPS-induced NLRP3 signaling pathway. In conclusion, the results showed that hyperin inhibited LPS-induced inflammatory response by inhibiting TLR4 and NLRP3 signaling pathways. Hyperin has potential application prospects in the treatment of sepsis-induced AKI.

MORG1+/- mice are protected from histological renal damage and inflammation in a murine model of endotoxemia

BACKGROUND

The MAPK-organizer 1 (MORG1) play a scaffold function in the MAPK and/or the PHD3 signalling paths. Recently, we reported that MORG1+/- mice are protected from renal injury induced by systemic hypoxia and acute renal ischemia-reperfusion injury via increased hypoxia-inducible factors (HIFs). Here, we explore whether MORG1 heterozygosity could attenuate renal injury in a murine model of lipopolysaccharide (LPS) induced endotoxemia.

METHODS

Endotoxemia was induced in mice by an intraperitoneal (i.p) application of 5 mg/kg BW LPS. The renal damage was estimated by periodic acid Schiff's staining; renal injury was evaluated by detection of urinary and plasma levels of neutrophil gelatinase-associated lipocalin and albumin/creatinine ratio via ELISAs. Renal mRNA expression was assessed by real-time PCR, whereas the protein expression was determined by immunohistochemistry or Western blotting.

RESULTS

LPS administration increased tubular injury, microalbuminuria, IL-6 plasma levels and renal TNF-α expression in MORG1 +/+ mice. This was accompanied with enhanced infiltration of the inflammatory T-cells in renal tissue and activation of the NF-κB transcription factors. In contrast, endotoxemic MORG1 +/- showed significantly less tubular injury, reduced plasma IL-6 levels, significantly decreased renal TNF-α expression and T-cells infiltration. In support, the renal levels of activated caspase-3 were lower in endotoxemic MORG1 +/- mice compared with endotoxemic MORG1 +/+ mice. Interestingly, LPS application induced a significantly higher accumulation of renal HIF-2α in the kidneys of MORG1+/- mice than in wild-type mice, accompanied with a diminished phosphorylation of IκB-α and IKK α,β and decreased iNOS mRNA in the renal tissues of the LPS-challenged MORG1+/- mice, indicating an inhibition of the NF-κB transcriptional activation.

CONCLUSIONS

MORG1 heterozygosity protects against histological renal damage and shows anti-inflammatory effects in a murine endotoxemia model through modulation of HIF-2α stabilisation and/or simultaneous inhibition of the NF-κB signalling. Here, we show for the first time that MORG1 scaffold could represent the missing link between innate immunity and inflammation.

Association of Heart Rate with N-Terminal Pro-B-Type Natriuretic Peptide in Septic Patients: A Prospective Observational Cohort Study

BACKGROUND

Excessive sympathetic stress has multiple adverse effects during critical illness including sepsis. Recent studies showed that heart rate control had a significant effect on reducing mortality in septic shock patients. Furthermore, elevated N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels in septic patients were reportedly associated with adverse outcome. However, no study has evaluated the relationship between hemodynamic profiles of septic patients and the circulating cardiac biomarker. Our objective was to determine whether hemodynamic profiles, specifically tachycardia and new-onset atrial fibrillation (AF), were associated with NT-proBNP elevation in septic patients.

METHODS

We consecutively enrolled patients admitted to our intensive care unit (ICU). NT-proBNP levels, heart rate, and rhythm at ICU admission were measured, and all clinical and laboratory data were prospectively collected. Tachycardia was defined as a heart rate of above 100 bpm.

RESULTS

Ninety-five patients out of 267 patients (35.6%) were diagnosed as sepsis. Of these septic patients, 47 presented with tachycardia and 6 developed new-onset AF. Multivariate Cox regression analysis revealed that tachycardia was an independent predictor of 28-day overall survival in septic patients (hazard ratio, 4.22; 95% confidence interval, 1.10-27.72; P < 0.05), but not in nonseptic patients. Multivariate linear regression analysis demonstrated that the presence of tachycardia was an independent determinant of NT-proBNP elevation (P < 0.05) in septic patients, but not in nonseptic patients.

CONCLUSIONS

Tachycardia was significantly and independently associated with NT-proBNP elevation and lower survival rate in septic patients, although no association was observed in nonseptic patients. Increased NT-proBNP in sepsis with tachycardia might predict poor outcomes in ICU.

The podoplanin-CLEC-2 axis inhibits inflammation in sepsis

Platelets play a critical role in vascular inflammation through the podoplanin and collagen/fibrin receptors, C-type-lectin-like-2 (CLEC-2) and glycoprotein VI (GPVI), respectively. Both receptors regulate endothelial permeability and prevent peri-vascular bleeding in inflammation. Here we show that platelet-specific deletion of CLEC-2 but not GPVI leads to enhanced systemic inflammation and accelerated organ injury in two mouse models of sepsis-intra-peritoneal lipopolysaccharide and cecal ligation and puncture. CLEC-2 deficiency is associated with reduced numbers of podoplanin-expressing macrophages despite increased cytokine and chemokine levels in the infected peritoneum. Pharmacological inhibition of the interaction between CLEC-2 and podoplanin regulates immune cell infiltration and the inflammatory reaction during sepsis, suggesting that activation of podoplanin underlies the anti-inflammatory action of platelet CLEC-2. We suggest podoplanin-CLEC-2 as a novel anti-inflammatory axis regulating immune cell recruitment and activation in sepsis.

Early septic insult in neonatal pigs increases serum and urinary soluble Fas ligand and decreases kidney function without inducing significant renal apoptosis

Apoptosis of renal tubular and glomerular cells during kidney disease involves activation of Fas ligand (FasL)-dependent death pathway. The significance of FasL in neonates with septic acute kidney injury (AKI) is unresolved, but an increase in renal FasL production, and/or infiltration of circulating FasL into the kidneys may occur following initial septic insult. Here, we examined whether soluble Fas ligand (sFasL) levels are altered during early phase of septic AKI in neonates. Six hours of polymicrobial sepsis elicited by cecal ligation and puncture (CLP) elevated serum C-reactive protein (CRP) (a bacteremia and sepsis marker) concentration in anesthetized and mechanically ventilated neonatal pigs. Serum creatinine and urea nitrogen concentrations were increased by ∼39% and 46%, respectively, following 6 h of CLP in the pigs. The urinary level of NGAL, an early marker of AKI was also elevated by ∼71% in the septic pigs. The basal concentration of sFasL in the serum and urine of neonatal pigs was similar. Six hours of CLP significantly increased serum and urine sFasL levels in the pigs by ∼24% and 68%, respectively. However, there was no evidence of caspase activation to suggest an induction of cellular apoptotic process in the kidneys of the septic pigs. These findings suggest that an increase in circulating and urinary sFasL during early septic AKI in neonatal pigs is not associated with renal apoptosis.

The impact of pretreatment with simvastatin on kidney tissue of rats with acute sepsis

It has been reported that changes in cytokine levels affect mitochondrial functions, levels of hypoxia-inducible factor α (HIF-1α), and tissue damage during sepsis. We aimed to investigate the effects of simvastatin pretreatment on mitochondrial enzyme activities, and on levels of ghrelin, HIF-1α, and thiobarbituric acid reactive substances (TBARS) in kidney tissue during sepsis. Rats were separated into four groups, namely, control, lipopolysaccharides (LPS) (20 mg/kg), simvastatin (20 mg/kg), and simvastatin + LPS. We measured the levels of mitochondrial enzyme activities and TBARS in the kidney using spectrophotometry. The histological structure of the kidney sections was examined after staining with hematoxylin and eosin. Tumor necrosis factor α (TNF-α), IL-10, HIF-1α, and ghrelin immunoreactivity were examined using proper antibodies. In tissue, TNF-α (p < 0.01) and HIF-1α (p < 0.05) levels were increased in the simvastatin + LPS and LPS groups. TBARS levels were higher in the LPS group than in the other groups (p < 0.01), but they were similar in the simvastatin + LPS and control groups (p > 0.05). Ghrelin immunoreactivity was lower in the LPS group (p < 0.05) and higher in the simvastatin + LPS group than in the LPS group (p < 0.01). We observed tubular damage in the sections of the LPS group. There were no differences in mitochondrial enzyme activities between the groups (p > 0.05). We observed that pretreatment of simvastatin caused favorable changes on ghrelin and TBARS levels in rats with sepsis.

Cardiorenal syndrome in sepsis: A narrative review

Multi-organ dysfunction is seen in nearly 40-60% of all patients presenting with sepsis, including renal and cardiac dysfunction. Cardiorenal syndrome type-5 reflects concomitant cardiac and renal dysfunction secondary to a systemic condition that primarily affects both organs, such as sepsis. There are limited data on the etiology, pathogenesis and clinical implications of cardiorenal syndrome in sepsis. Cardiac dysfunction and injury can be measured with cardiac biomarkers, echocardiographic dysfunction, and hemodynamic parameters. Acute kidney injury is systematically evaluated using serum creatinine and urine output criteria. This review seeks to systematically describe the epidemiology, risk factors, pathogenesis, diagnosis and management of cardiorenal syndrome type-5 in the setting of sepsis.

Cardiorenal Syndrome: Diagnosis and Management

Cardiorenal syndrome (CRS) has not been well characterized in veterinary medicine, yet an accurate appreciation of the kidney and the cardiovascular system and their interactions may have practical clinical implications. A consensus for cardiovascular-renal axis disorders of dogs and cats was recently attempted. The outcome of patients with CRS is likely to improve with the increasing awareness and ability to identify and understand the pathophysiologic characteristics of CRS. The utilization of existing and emerging organ-specific biomarkers with greater sensitivities than conventional diagnostics forecast new opportunities to diagnose and manage cardiac disease.

Serum Neutrophil Gelatinase-Associated Lipocalin: A Diagnostic Marker in Pediatric Sepsis

OBJECTIVES

Sepsis is a life-threatening condition that arises when the response of the body to infection injures its own tissues and organs. The early prediction of sepsis by current clinical and laboratory methods remains inadequate. Serum neutrophil gelatinase-associated lipocalin level is increased in sepsis irrespective of renal dysfunction. Therefore, we aimed to correlate the serum neutrophil gelatinase-associated lipocalin value determined at admission with clinical progression and severity of disease in critically ill children and to declare its role as a potential diagnostic and prognostic marker for sepsis in critically ill children in the emergency department.

DESIGN

A prospective cohort study.

SETTING

The study carried out at the PICU of Menoufia University Hospital.

PATIENTS

We serially enrolled 120 critically ill children admitted to the PICU at 2 fixed days per week in addition to 40 healthy children served as controls.

INTERVENTIONS

Clinical examination was performed including calculation of the Pediatric Risk of Mortality and Pediatric Index of Mortality 2. Serum neutrophil gelatinase-associated lipocalin measurement was performed for patients at admission and for the controls. Patients were followed up for 30 days. The discriminatory power of neutrophil gelatinase- associated lipocalin was determined using the receiver-operating characteristic and other predictive likelihood values.

MEASUREMENTS AND MAIN RESULTS

Serum neutrophil gelatinase-associated lipocalin level was significantly higher among the total patient cohort and those with sepsis than among the controls (p < 0.001), also in patients with systemic inflammatory response syndrome without sepsis and patients without systemic inflammatory response syndrome (p = 0.04 and <0.001). Furthermore, plasma level of neutrophil gelatinase-associated lipocalin was significantly elevated in nonsurvivors compared with survivors (p < 0. 001). Receiver-operating characteristic curve analysis exhibited an area under the curve of 0.84 for neutrophil gelatinase-associated lipocalin for diagnosis of sepsis, whereas C-reactive protein had an area under the curve of 0.79. Regarding the prognosis, neutrophil gelatinase-associated lipocalin had an area under the curve of 0.74 for prediction of mortality, whereas the area under the curve for Pediatric Risk of Mortality, Pediatric Index of Mortality 2, and C-reactive protein were 0.59, 0.58, and 0.62, respectively.

CONCLUSION

Overall, the data support the view that measurement at admission, serum neutrophil gelatinase-associated lipocalin results in substantial added value for early diagnosis and prognostication of sepsis in critically sick children.

Delayed Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase Inhibition by Trametinib Attenuates Systemic Inflammatory Responses and Multiple Organ Injury in Murine Sepsis

OBJECTIVE

The mitogen-activated protein kinase/extracellular signal-regulated kinase signaling pathway is an essential component of innate immunity necessary for mediating proinflammatory responses in the setting of sepsis. We previously demonstrated that the mitogen-activated protein kinase 1/2 inhibitor trametinib prevents endotoxin-induced renal injury in mice. We therefore assessed efficacy of trametinib in a more clinically relevant experimental model of sepsis.

DESIGN

Controlled in vivo laboratory study.

SETTING

University animal research laboratory.

SUBJECTS

Male C57BL/6 mice.

INTERVENTIONS

Mice were subjected to cecal ligation and puncture to induce sepsis or underwent sham operation as controls. Six hours after cecal ligation and puncture, mice were randomized to four experimental groups as follows: 1) sham control; 2) sham control + trametinib (1 mg/kg, IP); 3) cecal ligation and puncture; and 4) cecal ligation and puncture + trametinib. All animals received buprenorphine (0.05 mg/kg, SC) and imipenem/cilastatin (14 mg/kg, SC) in 1.5 mL of warm saline (40 mL/kg) at the 6-hour time point. Mice were euthanized at 18 hours after induction of cecal ligation and puncture.

MEASUREMENTS AND MAIN RESULTS

Trametinib inhibition of mitogen-activated protein kinase/extracellular signal-regulated kinase signaling 6 hours after cecal ligation and puncture attenuated increases in circulating proinflammatory cytokines (tumor necrosis factor-α, interleukin-1β, interleukin-6, and granulocyte macrophage colony-stimulating factor) and hypothermia at 18 hours. Trametinib also attenuated multiple organ injury as determined by serum creatinine, alanine aminotransferase, lactate dehydrogenase, and creatine kinase. At the organ level, trametinib completely restored peritubular capillary perfusion in the kidney. Restoration of microvascular perfusion was associated with reduced messenger RNA expression of well-characterized markers of proximal tubule injury. mitogen-activated protein kinase/extracellular signal-regulated kinase blockade attenuated cecal ligation and puncture-mediated up-regulation of cytokines (tumor necrosis factor-α, interleukin-1β) and restored interleukin-6 to control levels in the renal cortex, indicating the protective effects on the proximal tubule occur primarily through modulation of the proinflammatory response in sepsis.

CONCLUSIONS

These data reveal that the mitogen-activated protein kinase/extracellular signal-regulated kinase inhibitor trametinib attenuates systemic inflammation and multiple organ damage in a clinically relevant model of sepsis. Because trametinib has been safely used in humans, we propose that this drug might represent a translatable approach to limit organ injury in septic patients.

Growth Differentiation Factor-15 Deficiency Augments Inflammatory Response and Exacerbates Septic Heart and Renal Injury Induced by Lipopolysaccharide

Septic acute kidney injury (AKI) and myocardial dysfunction are leading causes of mortality with no accepted method of therapy. In this study we demonstrate the role of growth differentiating factor 15 (GDF15) in septic AKI and myocardial dysfunction using a murine lipopolysaccharide (LPS)-induced sepsis model and an in vitro cell culture system. Data show that GDF15 deficiency augments inflammatory response and exacerbates renal and cardiac injury induced by LPS, while over-expression of GDF15 protects the kidney and heart from LPS-induced organ dysfunction. Therefore, this study highlights the therapeutic potential of GDF15 in the treatment of endotoxin-induced sepsis.

Astragaloside IV Alleviates Lipopolysaccharide-Induced Acute Kidney Injury Through Down-Regulating Cytokines, CCR5 and p-ERK, and Elevating Anti-Oxidative Ability

Background

Astragaloside IV (AS-IV) has been shown to prevent ischemia-induced acute kidney injury (AKI) in rat models of ischemia and reperfusion. However, the effects of AS-IV on AKI during sepsis and endotoxinemia is unclear. The current study aimed to investigate the effects and molecular mechanisms of AS-IV on lipopolysaccharide (LPS)-induced AKI.

Material/Methods

Adult male CD-1 mice were randomly assigned into 6 groups (n=8/group): control group: mice were intraperitoneally (i.p.) injected with normal saline; LPS group (10 mg/kg, i.p.); low-dose AS-IV (25 mg/kg; gavage for 7 days) + LPS (i.p., 1 hour after last gavage) group; medial-dose AS-IV (50 mg/kg) + LPS group; high-dose AS-IV (100 mg/kg) + LPS group; high-dose AS-IV alone (100 mg/kg; gavage for 7 days) group. Blood samples were collected at 24 hours after LPS injection, and plasma uric acid and BUN were measured with colorimetric detection kits. The concentration of plasma tumor necrosis factor (TNF)-α and interleukin 1β, renal p-extracellular signal-regulated kinases, and urinary albumin were evaluated by ELISA. The expression of CCR5 in renal tissue was evaluated by PCR and Western blotting. Concentrations of glutathione (GSH) and reactive oxygen species (ROS) in renal tissue were also measured.

Results

AS-IV decreased LPS-stimulated production of blood TNF-α and IL-6, LPS-induced the expression of CCR5, and activation of ERK in the kidneys in a rodent model of endotoxinemia. AS-IV attenuated LPS-caused decreased GSH and increased ROS. It also attenuated LPS-induced increases in plasma uric acid, BUN, and urinary albumin.

Conclusions

AS-IV protects against AKI during bacterial endotoxinemia by attenuating expression of cytokines, CCR5, and p-ERK, and elevating anti-oxidative ability.

Protodioscin ameliorates fructose-induced renal injury via inhibition of the mitogen activated protein kinase pathway

BACKGROUND

High dietary fructose can cause metabolic syndrome and renal injury.

PURPOSE

The effects of protodioscin on metabolic syndrome and renal injury were investigated in mice receiving high-dose fructose.

METHODS

Mice received 30% (w/v) fructose in water and standard chow for 6 weeks to induce metabolic syndrome and were divided into four groups to receive carboxymethylcellulose sodium, allopurinol (5 mg/kg) and protodioscin (5 and 10 mg/kg) continuously for 6 weeks, respectively. The glucose intolerance, serum uric acid (UA), blood urea nitrogen (BUN), creatinine (Cr), total cholesterol (TC), triglyceride (TG), interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were determined.

RESULTS

Protodioscin significantly improved glucose intolerance and reduced the levels of serum UA, BUN, Cr, TC and TG. Histological examinations showed that protodioscin ameliorated glomerular and tubular pathological changes. Protodioscin significantly reduced renal concentrations of IL-1β, IL-6 and TNF-α by inhibiting the activation of nuclear factor-κB, c-Jun N-terminal kinase, p38 mitogen-activated protein kinase and extracellular signal-regulated kinase. In addition, the effect of protodioscin on the mitogen activated protein kinases (MAPK) pathway was examined.

CONCLUSION

Taken together, protodioscin is a potential drug candidate for high dietary fructose-induced metabolic syndrome and renal injury.

Modeling and Hemofiltration Treatment of Acute Inflammation

The body responds to endotoxins by triggering the acute inflammatory response system to eliminate the threat posed by gram-negative bacteria (endotoxin) and restore health. However, an uncontrolled inflammatory response can lead to tissue damage, organ failure, and ultimately death; this is clinically known as sepsis. Mathematical models of acute inflammatory disease have the potential to guide treatment decisions in critically ill patients. In this work, an 8-state (8-D) differential equation model of the acute inflammatory response system to endotoxin challenge was developed. Endotoxin challenges at 3 and 12 mg/kg were administered to rats, and dynamic cytokine data for interleukin (IL)-6, tumor necrosis factor (TNF), and IL-10 were obtained and used to calibrate the model. Evaluation of competing model structures was performed by analyzing model predictions at 3, 6, and 12 mg/kg endotoxin challenges with respect to experimental data from rats. Subsequently, a model predictive control (MPC) algorithm was synthesized to control a hemoadsorption (HA) device, a blood purification treatment for acute inflammation. A particle filter (PF) algorithm was implemented to estimate the full state vector of the endotoxemic rat based on time series cytokine measurements. Treatment simulations show that: (i) the apparent primary mechanism of HA efficacy is white blood cell (WBC) capture, with cytokine capture a secondary benefit; and (ii) differential filtering of cytokines and WBC does not provide substantial improvement in treatment outcomes vs. existing HA devices.

Pretreatment of curcumin attenuates coagulopathy and renal injury in LPS-induced endotoxemia

Disseminated intravascular coagulation (DIC) is a lethal situation in severe infections, characterized by the systemic formation of microthrombi complicated with bleeding tendency and organ dysfunction. Current clinical trials are not promising. In this study, we investigated the protective effect of curcumin in a lipopolysaccharide (LPS)-induced DIC model in rats. Experimental DIC was induced by sustained infusion of LPS (10 mg/kg body weight) for 4 h through the tail vein. Curcumin (60 mg/kg body weight) was given intraperitoneally 3 h before LPS infusion. Results showed that, in vivo, curcumin reduced the mortality rate of LPS-infused rats by decreasing the circulating TNF-α levels and the consumption of peripheral platelets and plasma fibrinogen. Furthermore, in vivo curcumin also has the effect of preventing the formation of fibrin deposition in the glomeruli of kidney. These results reveal the therapeutic potential of curcumin in infection-related coagulopathy of DIC.

p38-MAPK inhibition and endotoxin induced tubular dysfunction in men

Background: To evaluate the possibility of preventing endotoxin induced renal damage by p38-MAPK inhibition in a human model.

Design and Methods: Twenty-one healthy young male volunteers received 4 ng/kg Escherichia coli endotoxin as a single dose. Four groups of volunteers received an oral dose of placebo or 350, 700 or 1400 mg RWJ-67657, a p38-MAPK inhibitor, 20 min before endotoxin infusion. Urine samples were collected at set time intervals. The urinary excretion rate of β2-microglobulin and N-acetyl-β-D-glucosaminidase, as indicators of tubular dysfunction was determined.

Results: There was a significant increase of β2-microglobulin and N-acetyl-β-D-glucosaminidase urine excretion rate after endotoxin infusion in the placebo group. p38-MAPK inhibition prevented the increase of markers for tubulopathy.

Conclusions: Endotoxin infusion induces measurable tubular damage. Blocking the p38-MAPK may prevent this damage. The mechanism is unclear, but blocking TNF-α release is a possible explanation.

Kidney and Liver Injuries After Major Burns in Rats Are Prevented by Resolvin D2

OBJECTIVES

Innate immune dysfunction after major burn injuries increases the susceptibility to organ failure. Lipid mediators of inflammation resolution, e.g., resolvin D2, have been shown recently to restore neutrophil functionality and reduce mortality rate in a rat model of major burn injury. However, the physiological mechanisms responsible for the benefic activity of resolvin D2 are not well understood.

DESIGN

Prospective randomized animal investigation.

SETTING

Academic research setting.

SUBJECTS

Wistar male rats.

INTERVENTIONS

Animals were subjected to a full-thickness burn of 30% total body surface area. Two hours after burn, 25 ng/kg resolvin D2 was administered IV and repeated every day, for 8 days. At day 10 post burn, 2 mg/kg of lipopolysaccharide was administered IV, and the presence of renal and hepatic injuries was evaluated at day 11 post burn by histology, immunohistochemistry, and relevant blood chemistry.

MEASUREMENTS AND MAIN RESULTS

In untreated animals, we found significant tissue damage in the kidneys and liver, consistent with acute tubular necrosis and multifocal necrosis, and changes in blood chemistry, reflecting the deterioration of renal and hepatic functions. We detected less tissue damage and significantly lower values of blood urea nitrogen (26.4 ± 2.1 vs 36.0 ± 9.3 mg/dL; p ≤ 0.001), alanine aminotransferase (266.5 ± 295.2 vs 861.8 ± 813.7 U/L; p ≤ 0.01), and total bilirubin (0.13 ± 0.05 vs 0.30 ± 0.14 mg/dL; p ≤ 0.01) in resolvin D2-treated rats than in untreated animals. The mean blood pressure of all animals was above 65 mm Hg, indicating adequate tissue perfusion throughout the experiments. We measured significantly larger amounts of chromatin in the circulation of untreated than of resolvin D2-treated rats (575.1 ± 331.0 vs 264.1 ± 122.4 ng/mL; p ≤ 0.05) and identified neutrophil extracellular traps in kidney and liver tissues from untreated rats, consistent with the tissue damage.

CONCLUSIONS

Pathologic changes in kidney and liver tissues in a rat model of major burn and endotoxin insults are ameliorated by resolvin D2.

The Genetic Determinants of Renal Impairment Following Cardiac Surgery

Cardiac surgery is frequently performed, and acute renal dysfunction is a common adverse event following this procedure. Cardiac surgery-related renal injury independently predicts longer hospital stays and greater rates of morbidity and mortality. Although much work has been completed toward better understanding of this phenomenon, the state of knowledge concerning surgery-related renal injury remains limited. Currently, there is no effective paradigm to identify patients who are at risk for this condition; the specific mechanisms of renal injury during surgery are incompletely understood; and few therapies exist to prevent or treat this phenomenon. To better understand this common clinical problem, recent research has focused on the importance of genetic variability within the physiological and patho-physiological systems that underlie renal dysfunction following cardiac surgery. Emphasizing the importance of using genetics to elucidate molecular mechanisms of this disease, this article reviews the current literature on genetic polymorphisms and post cardiac surgery-related renal dysfunction.

Fabry's disease: an example of cardiorenal syndrome type 5

Cardiorenal syndrome type 5 (CRS-5) includes conditions where there is a simultaneous involvement of the heart and kidney from a systemic disorder. This is a bilateral organ cross talk. Fabry's disease (FD) is a devastating progressive inborn error of metabolism with lysosomal glycosphingolipid deposition in variety of cell types, capillary endothelial cells, renal, cardiac and nerve cells. Basic effect is absent or deficient activity of lysosomal exoglycohydrolase a-galactosidase A. Renal involvement consists of proteinuria, isosthenuria, altered tubular function, presenting in second or third decade leading to azotemia and end-stage renal disease in third to fifth decade mainly due to irreversible changes to glomerular, tubular and vascular structures, especially highlighted by podocytes foot process effacement. Cardiac involvement consists of left ventricular hypertrophy, right ventricular hypertrophy, arrhythmias (sinus node and conduction system impairment), diastolic dysfunction, myocardial ischemia, infarction, transmural replacement fibrosis, congestive heart failure and cardiac death. Management of FD is based on enzymatic replacement therapy and control of renal (with anti-proteinuric agents such as angiotensin-converting enzyme inhibitors-and/or angiotensin II receptor blockers), brain (coated aspirin, clopidogrel and statin to prevent strokes) and heart complications (calcium channel blockers for ischemic cardiomyopathy, warfarin and amiodarone or cardioverter device for arrhythmias).

Erythropoietin attenuates renal and pulmonary injury in polymicrobial induced-sepsis through EPO-R, VEGF and VEGF-R2 modulation

Sepsis remains the most important cause of acute kidney injury (AKI) and acute lung injury (ALI) in critically ill patients. The cecal ligation and puncture (CLP) model in experimental mice reproduces most of the clinical features of sepsis. Erythropoietin (EPO) is a well-known cytoprotective multifunctional hormone, which exerts anti-inflammatory, anti-oxidant, anti-apoptotic and pro-angiogenic effects in several tissues. The aim of this study was to evaluate the underlying mechanisms of EPO protection through the expression of the EPO/EPO receptor (EPO-R) and VEGF/VEF-R2 systems in kidneys and lungs of mice undergoing CLP-induced sepsis. Male inbred Balb/c mice were divided in three experimental groups: Sham, CLP, and CLP+EPO (3000IU/kg sc). Assessment of renal functional parameters, survival, histological examination, immunohistochemistry and/or Western blottings of EPO-R, VEGF and VEGF-R2 were performed at 18h post-surgery. Mice demonstrated AKI by elevation of serum creatinine and renal histologic damage. EPO treatment attenuates renal dysfunction and ameliorates kidney histopathologic changes. Additionally, EPO administration attenuates deleterious septic damage in renal cortex through the overexpression of EPO-R in tubular interstitial cells and the overexpression of the pair VEGF/VEGF-R2. Similarly CLP- induced ALI, as evidenced by parenchymal lung histopathologic alterations, was ameliorated through pulmonary EPO-R, VEGF and VEGF-R2 over expression suggesting and improvement in endothelial survival and functionality. This study demonstrates that EPO exerts protective effects in kidneys and lungs in mice with CLP-induced sepsis through the expression of EPO-R and the regulation of the VEGF/VEGF-R2 pair.

DDRGK1 in urine indicative of tubular cell injury in intensive care patients with serious infections

BACKGROUND

Acute kidney injury (AKI) is a life threatening condition. Despite intensive care treatment the occurrence cannot be predicted as very little indicators exist for direct measurement when tubular epithelial cell injury takes place. We therefore searched for novel peptide indicators expressed at intracellular level at the proximal kidney tubule for its appearance in urine samples.

OBJECTIVES

Establishing a test for urinary C20orf116 protein measurement.

PATIENTS AND METHODS

Generation of immunoreagents against C20orf116 also named DDRGK1. These were used to measure its presence in urine collected at 8-24 hours interval in a prospective study from 99 ICU patients at 4-6 time points. These patients received therapy because of serious infection and were categorized into 4 groups.

RESULTS

1) Ten tested highly for C20orf116 undergoing AKI graded Failure or Loss (3210 ± 4268 ng/mL) according to RIFLE criteria, all requiring renal replacement therapy (RRT) out of them 9 died. 2) Six patients with pre-existing kidney disease developed AKI and required RRT but had much lower C20orf116 levels of (33 ± 19), two of them died. 3) In contrast, out of 11 patients undergoing AKI grade Risk or Injury, four tested positive for C20orf116 but to much lower extent (66 ± 43) who recovered fully. 4) Out of 72 patients 25 tested positive (18 ± 12 ng/mL) not fulfilling criteria of AKI but with serum creatinine (sCr) rises of 1.2-1.4 (n = 52). Healthy donors (n = 48) showed no detectable C20orf116 at any time point.

CONCLUSIONS

C20orf116 excretion was detectable more than 24 hours before sCr rise could be measured; high level seemed to indicate severity of organ failure.

Autophagy Limits Endotoxemic Acute Kidney Injury and Alters Renal Tubular Epithelial Cell Cytokine Expression

Sepsis related acute kidney injury (AKI) is a common in-hospital complication with a dismal prognosis. Our incomplete understanding of disease pathogenesis has prevented the identification of hypothesis-driven preventive or therapeutic interventions. Increasing evidence in ischemia-reperfusion and nephrotoxic mouse models of AKI support the theory that autophagy protects renal tubular epithelial cells (RTEC) from injury. However, the role of RTEC autophagy in septic AKI remains unclear. We observed that lipopolysaccharide (LPS), a mediator of gram-negative bacterial sepsis, induces RTEC autophagy in vivo and in vitro through TLR4-initiated signaling. We modeled septic AKI through intraperitoneal LPS injection in mice in which autophagy-related protein 7 was specifically knocked out in the renal proximal tubules (ATG7KO). Compared to control littermates, ATG7KO mice developed more severe renal dysfunction (24hr BUN 100.1mg/dl +/- 14.8 vs 54.6mg/dl +/- 11.3) and parenchymal injury. After injection with LPS, analysis of kidney lysates identified higher IL-6 expression and increased STAT3 activation in kidney lysates from ATG7KO mice compared to controls. In vitro experiments confirmed an altered response to LPS in RTEC with genetic or pharmacological impairment of autophagy. In conclusion, RTEC autophagy protects against endotoxin induced injury and regulates downstream effects of RTEC TLR4 signaling.

Glycyrrhizic Acid Attenuates Sepsis-Induced Acute Kidney Injury by Inhibiting NF-κB Signaling Pathway

Glycyrrhizic acid (GA) is a major active ingredient in licorice. In our study, the effects of GA on acute kidney injury (AKI) in rats and its underlying molecular mechanisms were investigated. The sepsis model was produced by caecal ligation and puncture (CLP) in rats. The molecular and histological experiments were performed in the kidney tissues and serum samples of rats. According to the results obtained, GA alleviated sepsis-induced AKI by improving the pathological changes, decreasing the levels of blood urea nitrogen (BUN), creatinine (Cre), and increasing the survival rate of rats with AKI significantly. The production of inflammatory cytokines, such as TNF-α, IL-1β, and IL-6, was markedly inhibited by GA. Moreover, treatment with GA inhibited the production of nitric oxide (NO) and prostaglandin E2 (PGE2) and expression levels of induced nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in kidney tissues. Furtherly, the apoptosis in kidney tissue induced by AKI was suppressed by GA. Finally, GA could inhibit the activation of NF-κB signaling pathway. Our study suggests that GA alleviates sepsis-induced AKI by inhibiting the NF-κB signaling pathway, which provides a strong evidence for a new approach for treating sepsis-induced AKI.

Vitamin D3 pretreatment regulates renal inflammatory responses during lipopolysaccharide-induced acute kidney injury

Vitamin D receptor (VDR) is highly expressed in human and mouse kidneys. Nevertheless, its functions remain obscure. This study investigated the effects of vitamin D3 (VitD3) pretreatment on renal inflammation during lipopolysaccharide (LPS)-induced acute kidney injury. Mice were intraperitoneally injected with LPS. In VitD3 + LPS group, mice were pretreated with VitD3 (25 μg/kg) at 48, 24 and 1 h before LPS injection. As expected, an obvious reduction of renal function and pathological damage was observed in LPS-treated mice. VitD3 pretreatment significantly alleviated LPS-induced reduction of renal function and pathological damage. Moreover, VitD3 pretreatment attenuated LPS-induced renal inflammatory cytokines, chemokines and adhesion molecules. In addition, pretreatment with 1,25(OH)2D3, the active form of VitD3, alleviated LPS-induced up-regulation of inflammatory cytokines and chemokines in human HK-2 cells, a renal tubular epithelial cell line, in a VDR-dependent manner. Further analysis showed that VitD3, which activated renal VDR, specifically repressed LPS-induced nuclear translocation of nuclear factor kappa B (NF-κB) p65 subunit in the renal tubules. LPS, which activated renal NF-κB, reciprocally suppressed renal VDR and its target gene. Moreover, VitD3 reinforced the physical interaction between renal VDR and NF-κB p65 subunit. These results provide a mechanistic explanation for VitD3-mediated anti-inflammatory activity during LPS-induced acute kidney injury.

Zingerone ameliorates lipopolysaccharide-induced acute kidney injury by inhibiting Toll-like receptor 4 signaling pathway

Acute kidney injury (AKI) is a serious complication of sepsis. Zingerone, a phenolic alkanone isolated from ginger, has been reported to have anti-inflammatory effect. The aim of this study was to investigate the therapeutic effects of zingerone on lipopolysaccharide (LPS)-induced AKI in mice. Zingerone was administrated 1h after LPS challenge. The production of blood urea nitrogen (BUN) and creatinine were measured in this study. The expressions of inflammatory cytokines in serum and kidney tissues were detected by ELISA. The expressions of Toll-like receptor 4 (TLR4), MyD88, TRIF, Nuclear factor Kappa B (NF-κB) and IκB were measured by Western blotting. The results showed that zingerone suppressed LPS-induced BUN, creatinine, and inflammatory cytokines TNF-α, IL-6 and IL-1β levels in a dose-dependent manner. Zingerone also attenuated LPS-induced kidney histopathologic changes. Furthermore, zingerone was found to inhibit LPS-induced TLR4, MyD88, TRIF expression and NF-κB activation. In conclusion, the current study demonstrated that zingerone inhibited LPS-induced AKI by suppressing TLR4/NF-κB signaling pathway.

TNF causes changes in glomerular endothelial permeability and morphology through a Rho and myosin light chain kinase-dependent mechanism

A key function of the endothelium is to serve as a regulated barrier between tissue compartments. We have previously shown that tumor necrosis factor (TNF) plays a crucial role in lipopolysaccharide (LPS)‐induced acute kidney injury, in part by causing injury to the renal endothelium through its receptor TNFR1. Here, we report that TNF increased permeability to albumin in primary culture mouse renal endothelial cells, as well as human glomerular endothelial cells. This process occurred in association with changes in the actin cytoskeleton and was associated with gaps between previously confluent cells in culture and decreases in the tight junction protein occludin. This process was dependent on myosin light chain activation, as seen by its prevention with Rho‐associated kinase and myosin light chain kinase (MLCK) inhibitors. Surprisingly, permeability was not blocked by inhibition of apoptosis with caspase inhibitors. Additionally, we found that the renal glycocalyx, which plays an important role in barrier function, was also degraded by TNF in a Rho and MLCK dependent fashion. TNF treatment caused a decrease in the size of endothelial fenestrae, dependent on Rho and MLCK, although the relevance of this to changes in permeability is uncertain. In summary, TNF‐induced barrier dysfunction in renal endothelial cells is crucially dependent upon the Rho/MLCK signaling pathway.