Sepsis-induced acute kidney injury revisited: pathophysiology, prevention and future therapies. Curr Opin Crit Care. 2014;20:588-595. [PMID: 25320909 DOI: 10.1097/MCC.0000000000000153]

Oxidative Stress in the Pathophysiology of Kidney Disease: Implications for Noninvasive Monitoring and Identification of Biomarkers

Kidney disease represents a serious global health problem. One of the main concerns is its late diagnosis, only feasible in a progressed disease state. The lack of a clinical manifestation in the early stages and the fact that the commonly measured parameters of renal function are markedly reduced only during advanced stages of the disease are the main cause. Changes at the molecular level of the kidney tissue occur even before nitrogenous substances, such as creatinine and urea, start to accumulate in the blood. Renal proximal tubules contain a large number of mitochondria and are critical for the energy-demanding process of reabsorption of water and solutes. Mitochondria are the largest producers of oxygen radicals, which, in turn, increase the susceptibility of kidneys to oxidative stress-induced damage. Free radicals and prooxidants produced during acute or chronic kidney injury may further aggravate the course of the disease and play a role in the pathogenesis of subsequent complications. Prevention might be the solution in CKD, but patients are often reluctant to undergo preventive examinations. Noninvasive markers and the possibility to obtain samples at home might help to increase compliance. This review will provide an overview of the possible uses of markers of oxidative status in noninvasive biofluids in patients with renal disease.

Neutrophil, lymphocyte and platelet ratio as a predictor of mortality in septic-acute kidney injury patients

BACKGROUND

AKI is frequent in critically ill patients, in whom the leading cause of AKI is sepsis. The role of intrarenal and systemic inflammation appears to be significant in the pathophysiology of septic-AKI. The neutrophils to lymphocytes and platelets (N/LP) ratio is an indirect marker of inflammation. The aim of this study was to evaluate the prognostic ability of N/LP ratio at admission in septic-AKI patients admitted to an intensive care unit (ICU).

METHODS

This is a retrospective analysis of 399 septic-AKI patients admitted to the Division of Intensive Medicine of the Centro Hospitalar Universitário Lisboa Norte between January 2008 and December 2014. The Kidney Disease Improving Global Outcomes (KDIGO) classification was used to define AKI. N/LP ratio was calculated as: (Neutrophil count×100)/(Lymphocyte count×Platelet count).

RESULTS

Fifty-two percent of patients were KDIGO stage 3, 25.8% KDIGO stage 2 and 22.3% KDIGO stage 1. A higher N/LP ratio was an independent predictor of increased risk of in-hospital mortality in septic-AKI patients regardless of KDIGO stage (31.59±126.8 vs 13.66±22.64, p=0.028; unadjusted OR 1.01 (95% CI 1.00-1.02), p=0.027; adjusted OR 1.01 (95% CI 1.00-1.02), p=0.015). The AUC for mortality prediction in septic-AKI was of 0.565 (95% CI (0.515-0.615), p=0.034).

CONCLUSIONS

The N/LP ratio at ICU admission was independently associated with in-hospital mortality in septic-AKI patients.

Dexmedetomidine improved renal function in patients with severe sepsis: an exploratory analysis of a randomized controlled trial

Background

Dexmedetomidine has been reported to improve organ dysfunction in critically ill patients. In a recent randomized controlled trial (Dexmedetomidine for Sepsis in Intensive Care Unit (ICU) Randomized Evolution [DESIRE]), we demonstrated that dexmedetomidine was associated with reduced mortality risk among patients with severe sepsis. We performed this exploratory sub-analysis to examine the mechanism underlying improved survival in patients sedated with dexmedetomidine.

Methods

The DESIRE trial compared a sedation strategy with and without dexmedetomidine among 201 mechanically ventilated adult patients with sepsis across eight ICUs in Japan. In the present study, we included 104 patients with Acute Physiology and Chronic Health Evaluation II (APACHE II) scores of ≥ 23 (54 in the dexmedetomidine [DEX] group and 50 in the non-dexmedetomidine [non-DEX] group). Initially, we compared the changes in the sequential organ failure assessment (SOFA) scores from the baseline within 6 days after randomization between groups. Subsequently, we evaluated the variables comprising the organ component of the SOFA score that showed relevant improvement in the initial comparison.

Results

The mean patient age was 71.0 ± 14.1 years. There was no difference in the median APACHE II score between the two groups (29 [interquartile range (IQR), 25–31] vs. 30 [IQR, 25–33]; p = 0.35). The median SOFA score at the baseline was lower in the DEX group (9 [IQR, 7–11] vs. 11 [IQR, 9–13]; p = 0.01). While the renal SOFA subscore at the baseline was similar for both groups, it significantly decreased in the DEX group on day 4 (p = 0.02). During the first 6 days, the urinary output was not significantly different (p = 0.09), but serum creatinine levels were significantly lower (p = 0.04) in the DEX group. The 28-day and in-hospital mortality rates were significantly lower in the DEX group (22% vs. 42%; p = 0.03, 28% vs. 52%; p = 0.01, respectively).

Conclusion

A sedation strategy with dexmedetomidine is associated with improved renal function and decrease mortality rates among patients with severe sepsis.

Trial registration

This trial was registered on ClinicalTrials.gov (NCT01760967) on January 1, 2013.

Evaluation of the Risk Factors for Acute Kidney Injury in Neonates Exposed to Antenatal Indomethacin

OBJECTIVE

Evidence is limited about important maternal and neonatal risk factors that affect neonatal renal function. The incidence of acute kidney injury (AKI) and identification of associated risk factors in neonates exposed to antenatal indomethacin was studied.

METHODS

A retrospective cohort of neonates exposed to antenatal indomethacin within 1 week of delivery was analyzed for development of AKI up to 15 days of life. Adjusted hazard ratios (HRs) and 95% CIs for AKI risk were calculated in time-dependent Cox proportional hazards models.

RESULTS

Among 143 neonates with mean gestational age of 28.3 ± 2.4 weeks, AKI occurred in 62 (43.3%), lasting a median duration of 144 hours (IQR, 72-216 hours). Neonates with AKI had greater exposure to postnatal NSAIDs (48.4% vs 9.9%, p < 0.001) and inotropes (37.1% vs 3.7%, p < 0.001) compared with neonates without AKI. In multivariable-adjusted models, increased AKI risk was observed with antenatal indomethacin doses received within 24 to 48 hours (HR, 1.6; 95% CI, 1.28-1.94; p = 0.036) and <24 hours (HR, 2.33; 95% CI, 1.17-4.64; p = 0.016) prior to delivery. Further, postnatal NSAIDs (HR, 2.8; 95% CI, 1.03-7.61; p = 0.044), patent ductus arteriosus (HR, 4.04; 95% CI, 1.27-12.89; p = 0.018), and bloodstream infection (HR, 3.01; 95% CI, 1.37-6.60; p = 0.006) were associated significantly with increased risk of AKI following antenatal indomethacin. Neonates with AKI experienced more bloodstream infection, severe intraventricular hemorrhage, patent ductus arteriosus, respiratory distress syndrome, and longer hospitalization.

CONCLUSIONS

Extended risk of AKI with antenatal indomethacin deserves clinical attention among this population at an already increased AKI risk.

Aerosol inhalation of a hydrogen-rich solution restored septic renal function

Sepsis-related acute kidney injury (AKI) is known to be caused by inflammation. We explored the renal protective effects of aerosol inhalation of a hydrogen-rich solution (HRS; hydrogen gas dissolved to saturation in saline) in a mouse model of septic AKI. Septic AKI was induced through 18 hours of cecal ligation and puncture. AKI occurred during the early stage of sepsis, as evidenced by increased blood urea nitrogen and serum creatinine levels, pathological changes, renal fibrosis and renal tubular epithelial cell apoptosis, accompanied by macrophage infiltration and M1 macrophage-associated pro-inflammatory cytokine (Il-6 and Tnf-α) generation in renal tissues. Aerosol inhalation of the HRS increased anti-inflammatory cytokine (Il-4 and Il-13) mRNA levels in renal tissues and promoted macrophage polarization to the M2 type, which generated additional anti-inflammatory cytokines (Il-10 and Tgf-β). Ultimately, aerosol inhalation of HRS protected the kidneys and increased survival among septic mice. HRS was confirmed to promote M2 macrophage polarization in lipopolysaccharide-stimulated RAW 264.7 cells. The TGF-β1 receptor inhibitor SB-431542 partly reversed the effects of HRS on renal function, fibrosis, tubular epithelial cell apoptosis and senescence in mice. Thus, HRS aerosol inhalation appears highly useful for renal protection and inflammation reduction in septic AKI.

Urolithiasis Is a Risk Factor for Uroseptic Shock and Acute Kidney Injury in Patients With Urinary Tract Infection

Urinary tract infection (UTI) is a common complication in patients with urolithiasis. This study aimed to compare clinical manifestations and treatment outcomes among UTI patients with or without urolithiasis. It also focused on identifying relationships among urolithiasis, uroseptic shock, and acute kidney injury (AKI). This retrospective study enrolled hospitalized UTI patients who underwent imaging in an acute care setting from January 2006 to March 2015. Of 662 participants enrolled, 113 (17.1%) had urolithiasis, 107 (16.2%) developed uroseptic shock, and 184 (27.8%) developed AKI. A multivariate logistic regression analysis showed that in UTI patients, urolithiasis is associated with an increased risk of uroseptic shock (OR 1.80, 95% CI: 1.08-3.02, P = 0.025), AKI (OR 1.95, 95% CI: 1.22-3.12, P = 0.005), and bacteremia (OR 1.68, 95% CI: 1.08-2.64, P = 0.022). Urolithiasis is common in UTI patients and is associated with an increased risk of uroseptic shock and AKI.

Heterogenous Renal Injury Biomarker Production Reveals Human Sepsis-Associated Acute Kidney Injury Subtypes

Supplemental Digital Content is available in the text.

To identify mechanisms associated with sepsis-acute kidney injury based on the expression levels of renal injury biomarkers, neutrophil gelatinase–associated lipocalin, and kidney injury molecule-1 in renal biopsies which may allow the identification of sepsis-acute kidney injury patient subtypes.

Cell-free hemoglobin augments acute kidney injury during experimental sepsis

Acute kidney injury is a common complication of severe sepsis and contributes to high mortality. The molecular mechanisms of acute kidney injury during sepsis are not fully understood. Because hemoproteins, including myoglobin and hemoglobin, are known to mediate kidney injury during rhabdomyolysis, we hypothesized that cell-free hemoglobin (CFH) would exacerbate acute kidney injury during sepsis. Sepsis was induced in mice by intraperitoneal injection of cecal slurry (CS). To mimic elevated levels of CFH observed during human sepsis, mice also received a retroorbital injection of CFH or dextrose control. Four groups of mice were analyzed: sham treated (sham), CFH alone, CS alone, and CS + CFH. The addition of CFH to CS reduced 48-h survival compared with CS alone (67% vs. 97%, P = 0.001) and increased the severity of illness. After 24 and 48 h, CS + CFH mice had a reduced glomerular filtration rate from baseline, whereas sham, CFH, and CS mice maintained baseline glomerular filtration rate. Biomarkers of acute kidney injury, neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1), were markedly elevated in CS+CFH compared with CS (8-fold for NGAL and 2.4-fold for KIM-1, P < 0.002 for each) after 48 h. Histological examination showed a trend toward increased tubular injury in CS + CFH-exposed kidneys compared with CS-exposed kidneys. However, there were similar levels of renal oxidative injury and apoptosis in the CS + CFH group compared with the CS group. Kidney levels of multiple proinflammatory cytokines were similar between CS and CS + CFH groups. Human renal tubule cells (HK-2) exposed to CFH demonstrated increased cytotoxicity. Together, these results show that CFH exacerbates acute kidney injury in a mouse model of experimental sepsis, potentially through increased renal tubular injury.

Nicotine reverses the enhanced renal vasodilator capacity in endotoxic rats: Role of α7/α4β2 nAChRs and HSP70

BACKGROUND

Nicotine alleviates renal inflammation and injury induced by endotoxemia. This study investigated (i) the nicotine modulation of hemodynamic and renal vasodilatory responses to endotoxemia in rats, and (ii) roles of α7 or α4β2-nAChRs and related HSP70/TNFα/iNOS signaling in the interaction.

METHODS

Endotoxemia was induced by ip lipopolysaccharide (5 mg/kg/day, for 2 days) and changes in systolic blood pressure and vasodilator responsiveness of isolated perfused kidney to acetylcholine or 5'-N-ethylcarboxamidoadenosine (NECA, adenosine receptor agonist) were evaluated.

RESULTS

Lipopolysaccharide had no effect on serum creatinine, reduced blood pressure, and increased renal vasodilations induced by acetylcholine or NECA in male and female preparations. Immunohistochemical analyses showed that lipopolysaccharide reduced renal HSP70 expression, but increased α7-nAChRs, α4β2-nAChRs and iNOS expressions. The co-administration of aminoguanidine (iNOS inhibitor), pentoxifylline (TNFα inhibitor), or nicotine attenuated lipopolysaccharide mediation of renal vasodilations and elevations in α7/α4β2-nAChR and iNOS expressions. Nicotine also reversed the downregulating effect of lipopolysaccharide on HSP70 expression. α7-nAChRs (methyllycaconitine citrate, MLA) or α4β2-nAChRs (dihydro-β-erythroidine, DHβE) blockade potentiated the lipopolysaccharide enhancement of renal vasodilations, and abolished the depressant effect of nicotine on lipopolysaccharide responses. A similar abolition of nicotine effects was seen after HSP70 inhibition by quercetin. Alternatively, lipopolysaccharide hypotension was eliminated in rats treated with DHβE/nicotine or quercetin/nicotine regimen in contrast to no effect for nicotine alone or combined with MLA.

CONCLUSIONS

These findings establish that nicotine offsets lipopolysaccharide facilitation of renal vasodilations possibly through a crosstalk between HSP70 and nAChRs of the α7 and α4β2 types.

Association between preoperative aspirin and acute kidney injury following coronary artery bypass grafting

OBJECTIVE

To test the hypothesis that preoperative aspirin administered within 24 hours before coronary artery bypass grafting (CABG) could reduce the incidence of postoperative acute kidney injury (AKI) following CABG.

METHODS

In this retrospective study, 696 patients were assigned to groups according to the time interval between their last aspirin dose administration and the time of surgery. A total of 322 patients received aspirin ≤24 hours before CABG, and 374 patients received aspirin between 24 and 48 hours before CABG. The primary outcome was postoperative AKI of any stage as defined by the Kidney Disease Improving Global Outcomes criteria. Propensity score matching selected 274 pairs for the final comparison.

RESULTS

Multivariable analysis showed that administration of aspirin within 24 hours of CABG was independently associated with reduction of AKI incidence by 36% (odds ratio, 0.64; 95% confidence interval, 0.45-0.91; P = .014). It was also noted that patients receiving their last aspirin dose ≤24 hours before CABG had a significantly higher glomerular filtration rate at discharge compared with patients who received aspirin between 24 and 48 hours before CABG. Propensity score matching analysis showed that patients receiving aspirin within 24 hours before CABG had a lower incidence of AKI compared with patients who discontinued aspirin between 24 and 48 hours before CABG (25.1% vs 36.8%; P = .004).

CONCLUSIONS

Continuation of aspirin until the day of surgery, with the last aspirin dose administered ≤24 hours before CABG, is associated with a significant reduction of postoperative AKI.

The role of platelets in acute kidney injury

Acute kidney injury (AKI), a major public health problem associated with high mortality and increased risk of progression towards end-stage renal disease, is characterized by the activation of intra-renal haemostatic and inflammatory processes. Platelets, which are present in high numbers in the circulation and can rapidly release a broad spectrum of bioactive mediators, are important acute modulators of inflammation and haemostasis, as they are the first cells to arrive at sites of acute injury, where they interact with endothelial cells and leukocytes. Diminished control of platelet reactivity by endothelial cells and/or an increased release of platelet-activating mediators can lead to uncontrolled platelet activation in AKI. As increased platelet sequestration and increased expression levels of the markers P-selectin, thromboxane A₂, CC-chemokine ligand 5 and platelet factor 4 on platelets have been reported in kidneys following AKI, platelet activation likely plays a part in AKI pathology. Results from animal models and some clinical studies highlight the potential of antiplatelet therapies in the preservation of renal function in the context of AKI, but as current strategies also affect other cell types and non-platelet-derived mediators, additional studies are required to further elucidate the extent of platelet contribution to the pathology of AKI and to determine the best therapeutic approach by which to specifically target related pathogenic pathways.

Basic Principles of Antibiotics Dosing in Patients with Sepsis and Acute Kidney Damage Treated with Continuous Venovenous Hemodiafiltration

Sepsis is the leading cause of acute kidney damage in patients in intensive care units. Pathophysiological mechanisms of the development of acute kidney damage in patients with sepsis may be hemodynamic and non-hemodynamic. Patients with severe sepsis, septic shock and acute kidney damage are treated with continuous venovenous hemodiafiltration. Sepsis, acute kidney damage, and continuous venovenous hemodiafiltration have a significant effect on the pharmacokinetics and pharmacodynamics of antibiotics. The impact dose of antibiotics is increased due to the increased volume of distribution (increased administration of crystalloids, hypoalbuminemia, increased capillary permeability syndrome toproteins). The dose of antibiotic maintenance depends on renal, non-renal and extracorporeal clearance. In the early stage of sepsis, there is an increased renal clearance of antibiotics, caused by glomerular hyperfiltration, while in the late stage of sepsis, as the consequence of the development of acute renal damage, renal clearance of antibiotics is reduced. The extracorporeal clearance of antibiotics depends on the hydrosolubility and pharmacokinetic characteristics of the antibiotic, but also on the type of continuous dialysis modality, dialysis dose, membrane type, blood flow rate, dialysis flow rate, net filtration rate, and effluent flow rate. Early detection of sepsis and acute kidney damage, early target therapy, early administration of antibiotics at an appropriate dose, and early extracorporeal therapy for kidney replacement and removal of the inflammatory mediators can improve the outcome of patients with sepsis in intensive care units.

MiR-106a aggravates sepsis-induced acute kidney injury by targeting THBS2 in mice model

PURPOSE

To investigate the role and related mechanisms of miR-106a in sepsis-induced AKI.

METHODS

Serum from sepsis and healthy patients was collected, sepsis mouse model was established by cecal ligation and puncture (CLP). TCMK-1 cells were treated with lipopolysaccharide (LPS) and transfected with THBS2-small interfering RNA (siTHBS2), miR-106a inhibitor, miR-106a mimics and their negative controls (NCs). The expression of miR-106a, thrombospondin 2 (THBS2), Bax, cleaved caspase-3 and Bcl-2, cell viability, relative caspase-3 activity and TNF-α, IL-1β, IL-6 content were respectively detected by quantitative real-time polymerase chain reaction (qRT-PCR), western blotting, Cell Counting Kit-8 (CCK-8) and enzyme linked immunosorbent assay (ELISA). The relationship between miR-106a and THBS2 was confirmed by dual luciferase reporter assay.

RESULTS

MiR-106a was up-regulated in serum of sepsis patients, CLP-induced mice models and LPS-induced TCMK-1 cells. LPS reduced cell viability and Bcl-2 expression, and increased caspase-3 activity, Bax expression, the content of TNF-α, IL-1β, IL-6. THBS2 was a target of miR-106a. The decreases of caspase-3 activity, TNF-α, IL-1β, IL-6, Bax expression and the increases of cell viability, Bcl-2 expression caused by miR-106a knockdown were reversed when THBS2 silencing in LPS-stimulated TCMK-1 cells.

CONCLUSION

MiR-106a aggravated LPS-induced inflammation and apoptosis of TCMK-1 cells via regulating THBS2 expression.

LPS-Binding Protein Modulates Acute Renal Fibrosis by Inducing Pericyte-to-Myofibroblast Trans-Differentiation through TLR-4 Signaling

During sepsis, the increased synthesis of circulating lipopolysaccharide (LPS)-binding protein (LBP) activates LPS/TLR4 signaling in renal resident cells, leading to acute kidney injury (AKI). Pericytes are the major source of myofibroblasts during chronic kidney disease (CKD), but their involvement in AKI is poorly understood. Here, we investigate the occurrence of pericyte-to-myofibroblast trans-differentiation (PMT) in sepsis-induced AKI. In a swine model of sepsis-induced AKI, PMT was detected within 9 h from LPS injection, as evaluated by the reduction of physiologic PDGFRβ expression and the dysfunctional α-SMA increase in peritubular pericytes. The therapeutic intervention by citrate-based coupled plasma filtration adsorption (CPFA) significantly reduced LBP, TGF-β, and endothelin-1 (ET-1) serum levels, and furthermore preserved PDGFRβ and decreased α-SMA expression in renal biopsies. In vitro, both LPS and septic sera led to PMT with a significant increase in Collagen I synthesis and α-SMA reorganization in contractile fibers by both SMAD2/3-dependent and -independent TGF-β signaling. Interestingly, the removal of LBP from septic plasma inhibited PMT. Finally, LPS-stimulated pericytes secreted LBP and TGF-β and underwent PMT also upon TGF-β receptor-blocking, indicating the crucial pro-fibrotic role of TLR4 signaling. Our data demonstrate that the selective removal of LBP may represent a therapeutic option to prevent PMT and the development of acute renal fibrosis in sepsis-induced AKI.

Host-Derived Delta-Like Canonical Notch Ligand 1 as a Novel Diagnostic Biomarker for Bacterial Sepsis-Results From a Combinational Secondary Analysis

Background: Sepsis is a life-threatening syndrome, resulting from a dysbalanced host response to infection. However, especially the early, pro-inflammatory immune response in sepsis is similar to other inflammatory conditions without infectious cause, e.g., trauma or surgery. This aspect challenges the value of current biomarkers for diagnosis, as these are often broadly induced. We earlier identified Delta-like Protein 1 (DLL1), a canonical Notch ligand, to be released from monocytes upon bacterial stimulation. Considering the importance of monocytes in the pathophysiology of sepsis, we hypothesized that this mechanism might occur also in the clinical setting and DLL1 might serve as a biomarker of life-threatening bacterial infection.

Methods: We combined samples from three different studies, including subgroups of patients with sepsis (n = 80), surgical patients (n = 50), trauma patients (n = 36), as well as healthy controls (n = 50). We assessed plasma concentrations of DLL1 using ELISA. We performed Area-under-receiver-operator-curve (AUROC) analysis to evaluate the diagnostic performance of DLL1 compared to leucocytes, C-reactive protein (CRP), and procalcitonin (PCT).

Results: Plasma concentrations of DLL1 were strongly elevated already at sepsis onset and maintained elevated until day 7. In contrast, neither surgical patients nor patients after severe trauma presented with elevated levels, while conventional biomarkers of inflammation (e.g., leucocytes and CRP), responded. AUROC analysis revealed a cut-off of 30 ng/ml associated with the best diagnostic performance, yielding a superior accuracy of 91% for DLL1, compared to 75, 79, and 81% for CRP, leucocytes, and PCT.

Conclusion: DLL1 is a novel host-derived biomarker for the diagnosis of sepsis with a better performance compared to established ones, most likely due to its high robustness in non-infectious inflammatory responses.

Clinical Trial Registration:POCSEP-Trial DRKS00008090; MIRSI DRKS00005463; SPRINT DRKS00010991.

Endotoxemia-induced endothelial fibrosis inhibition improves hypotension, tachycardia, multiple organ dysfunction syndrome, cytokine response, oxidative stress, and survival

Sepsis syndrome is the leading cause of mortality in critically ill patients admitted to intensive care. However, current therapies for sepsis treatment are unsatisfactory, and the mortality rate is still high. The main pathological characteristics observed during sepsis syndrome and endotoxemia include hypotension, tachycardia, multiple organ dysfunction syndrome (MODS), tissue damage, and cytokine and oxidative bursts. These conditions severely decrease the survival rates of endotoxemic patients. As a consequence of endotoxemia, large amounts of endotoxin circulate in the bloodstream throughout the vascular system and interact directly with endothelial cells that cover the inner wall of blood vessels. Endothelial cells exposed to lipopolysaccharides exhibit conversion to activated fibroblasts. By means of endotoxin-induced endothelial fibrosis, endothelial cells downregulate the expression of endothelial proteins and express fibrotic and ECM markers throughout endothelial protein expression reprogramming. Although endotoxin-induced endothelial fibrosis should, in theory, be detrimental to endothelial vascular function, the role of endothelial fibrosis in sepsis syndrome or endotoxemia is not known. Therefore, we employed a rat model to investigate whether the inhibition of endotoxin-induced endothelial fibrosis protects against endotoxemia and whether this inhibition increases survival. Our results show that the inhibition of endotoxin-induced endothelial fibrosis reduced both hypotension and tachycardia. Endotoxemia-induced MODS was also decreased when endothelial fibrosis was inhibited; treated rats showed normal kidney and liver function, inhibition of muscle mass wasting and normal glycemia. Liver and kidney histology was preserved, and organ fibrosis and fibrotic protein expression were reduced. Furthermore, pro-inflammatory cytokine secretion and NOX-2-mediated oxidative stress bursts were decreased when endothelial fibrosis was inhibited. Remarkably, the risk of death associated with sepsis syndrome at early and late time points was decreased when endotoxemia-induced endothelial fibrosis was inhibited, and a significant increase in survival was observed. These results reveal a potential novel treatment strategy to protect against sepsis syndrome and endotoxemia.

Monophosphoryl lipid A induces protection against LPS in medullary thick ascending limb through induction of Tollip and negative regulation of IRAK-1

LPS inhibits HCO3- absorption in the medullary thick ascending limb (MTAL) through a Toll-like receptor 4 (TLR4)-myeloid differentiation factor 88 (MyD88)-extracellular signal-regulated kinase (ERK) pathway that is upregulated by sepsis. Pretreatment with the nontoxic immunomodulator monophosphoryl lipid A (MPLA) prevents inhibition by LPS through activation of a TLR4-TIR-domain-containing adaptor-inducing interferon-β (TRIF)-phosphatidylinositol 3-kinase (PI3K) pathway that prevents LPS-induced ERK activation. Here, we identified the molecular mechanisms that underlie the protective inhibitory interaction between the MPLA-PI3K and LPS-ERK pathways. Treatment of mouse MTALs with LPS in vitro increased phosphorylation of IL-1 receptor-associated kinase (IRAK)-1, a critical mediator of LPS signaling downstream of TLR4-MyD88. Activation of ERK by LPS was eliminated by a selective IRAK-1 inhibitor, establishing IRAK-1 as the upstream mediator of ERK activation. Pretreatment of MTALs with MPLA in vitro prevented LPS-induced IRAK-1 activation; this effect was dependent on PI3K. Treatment of MTALs with MPLA increased expression of Toll-interacting protein (Tollip), an inducible protein that negatively regulates LPS signaling by inhibiting IRAK-1. The MPLA-induced increase in Tollip protein level was prevented by PI3K inhibitors. In coimmunoprecipitation experiments, MPLA increased the amount of Tollip stably bound to IRAK-1, an interaction that inhibits IRAK-1 activation. These results support a mechanism whereby MPLA increases Tollip expression in the MTAL through a PI3K-dependent pathway. Tollip, in turn, inhibits LPS-induced TLR4 signaling by suppressing activation of IRAK-1, thereby preventing activation of ERK that inhibits HCO3- absorption. These studies show that MPLA induces reprogramming of MTAL cells that protects against LPS stimulation and identify IRAK-1 and Tollip as new therapeutic targets to prevent renal tubule dysfunction in response to infectious and inflammatory stimuli.

RIPK3 mediates renal tubular epithelial cell apoptosis in endotoxin‑induced acute kidney injury

Renal tubular epithelial cell apoptosis is an important pathological mechanism of septic acute kidney injury (AKI). Endotoxin, also known as lipopolysaccharide (LPS), has a key role in septic AKI and can directly induce tubular epithelial cell apoptosis. The upregulation of receptor-interacting protein kinase 3 (RIPK3) in tubular epithelial cells has been reported in septic AKI, with RIPK3 mediating apoptosis in several cell types. In the present study, the effect of RIPK3 on endotoxin-induced AKI was investigated in mouse tubular epithelial cell apoptosis in vitro and in vivo. It was found that the expression of RIPK3 was markedly increased in endotoxin-induced AKI. Endotoxin-induced AKI and tubular epithelial cell apoptosis could be attenuated by GSK′872, a RIPK3 inhibitor. LPS stimulation also upregulated RIPK3 expression in tubular epithelial cells in a time-dependent manner. Both RIPK3 inhibitor and small interfering RNA (siRNA) targeting RIPK3 reduced LPS-induced tubular epithelial cell apoptosis in vitro. The expression of the proapoptotic protein Bax was induced by LPS and reversed by GSK′872 or RIPK3-siRNA. The present study revealed that RIPK3 mediated renal tubular cell apoptosis in endotoxin-induced AKI. RIPK3 may be a potential target for the prevention of renal tubular cell apoptosis in endotoxin-induced AKI.

[Quercetin alleviates lipopolysaccharide-induced acute kidney injury in mice by suppressing TLR4/NF-κB pathway]

OBJECTIVE

To investigate the protective effect of quercetin against lipopolysaccharide (LPS)- induced acute kidney injury (AKI) in mice and explore its mechanism.

METHODS

Forty male BALB/c mice were randomly divided into control group (with saline treatment), 15 mg/kg LPS group, and quercetin-treated groups with intragastric quercetin treatment (once daily for 3 consecutive days) at low (25 mg/kg) and high (50 mg/kg) dose prior to 15 mg/kg LPS injection. LPS was administered by intraperitoneally injection 1 after the last gavage of quercetin. The mice were sacrificed 24 h after LPS injection for analysis of kidney pathologies, blood urea nitrogen (BUN) and creatinine levels; serum levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6 were detected by ELISA, and the expressions of Toll-like receptor-4 (TLR4), MyD88, TRAF-6 and NF-κBp65 in the kidney were detected by Western blotting.

RESULTS

Quercetin significantly lessened renal pathologies, lowered BUN and creatinine levels (P < 0.05) and inhibited TNF-α, IL-1β, and IL-6 production in mice with LPS-induced AKI (P < 0.05). Pretreatment with quercetin also significantly inhibited TLR4, MyD88, and TRAF-6 expressions and NF-κBp65 activation in the kidneys of the rats with LPS challenge (P < 0.05).

CONCLUSIONS

Quercetin pretreatment can protect mice against LPSinduced AKI by inhibiting TLR4/NF-κB signaling pathway.

MiR-21-3p Plays a Crucial Role in Metabolism Alteration of Renal Tubular Epithelial Cells during Sepsis Associated Acute Kidney Injury via AKT/CDK2-FOXO1 Pathway

Objective

Sepsis and associated acute kidney injury (SAKI) are determined to be closely related to poor prognosis. Because the metabolic alterations of tubular epithelial cells (TECs) are crucial for the occurrence and development of SAKI, we carried out this present study to identify the metabolism changes of TECs during SAKI and relevant mechanisms.

Methods

Rat SAKI model and rat tubular epithelial cell line were used in our study. ELISA was used to determine the serum cytokines levels. Protein expressions were examined with Western-Blotting and the transcriptions of RNAs were determined with qRT-PCR. ADP/ATP assay and Oil Red O staining were used to examine the energy and lipid metabolism, respectively. Dual-luciferase reporter assay was carried out to determine the interactions between miRNA and specific proteins. Cell cycle arrest and apoptosis were determined with flow cytometry.

Results

Sepsis and AKI were induced 12 h after CLP. Energy and lipid metabolism reduced significantly while FOXO1 levels increased remarkably in TECs during SAKI. The expressions of both AKT and CDK2 and the transcriptions of relevant mRNAs reduced significantly in TECs during SAKI while miR-21-3p expression increased remarkably. Both AKT and CDK2 were determined as the direct targets of miR-21-3p. Furthermore, by in vitro experiments, it was demonstrated that FOXO1 levels were regulated by miR-21-3p in TECs via AKT/CDK2 and AKT/CDK2-FOXO1 pathway was crucial in the regulations of miR-21-3p on lipid metabolism, cell cycle arrest, and apoptosis of TECs.

Conclusions

MiR-21-3p mediates metabolism and cell fate alterations of TECs via manipulating AKT/CDK2-FOXO1 pathway, and that is crucial in the regulation of energy metabolism of TECs during SAKI.

Vitamin D receptor activation protects against lipopolysaccharide-induced acute kidney injury through suppression of tubular cell apoptosis

Acute kidney injury (AKI) is a common complication of sepsis characterized by a rapid degradation of renal function. The effect of vitamin D on AKI remains poorly understood. Here, we showed that vitamin D receptor (VDR) activation protects against lipopolysaccharide (LPS)-induced AKI by blocking renal tubular epithelial cell apoptosis. Mice lacking VDR developed more severe AKI than wild-type (WT) control mice after LPS treatment, which was manifested by marked increases in body weight loss and accumulation of serum blood urea nitrogen and creatinine as well as the magnitude of apoptosis of tubular epithelial cells. In the renal cortex, LPS treatment led to more dramatic downregulation of Bcl-2, more robust induction of p53-upregulated modulator of apoptosis (PUMA) and miR-155, and more severe caspase-3 activation in VDR knockout mice compared with WT control mice. Conversely, paricalcitol pretreatment markedly prevented LPS-induced AKI. Paricalcitol ameliorated body weight loss, attenuated serum blood urea nitrogen and creatinine accumulation, blocked tubular cell apoptosis, prevented the suppression of Bcl-2, and reversed PUMA and miR-155 induction and caspase-3 activation in LPS-treated WT mice. In HK2 cells, LPS induced PUMA and miR-155 by activating NF-κB, whereas 1,25(OH)2D3 blocked PUMA and miR-155 induction by repressing NF-κB activation. Both PUMA and miR-155 target Bcl-2 to promote apoptosis; namely, PUMA inhibits Bcl-2 activity, whereas miR-155 promotes Bcl-2 mRNA degradation and inhibits Bcl-2 protein translation. Collectively, these data provide strong evidence that LPS induces tubular cell apoptosis via upregulating PUMA and miR-155, whereas vitamin D/VDR signaling protects against AKI by blocking NF-κB-mediated PUMA and miR-155 upregulation.

3,3'‑Diindolylmethane mitigates lipopolysaccharide‑induced acute kidney injury in mice by inhibiting NOX‑mediated oxidative stress and the apoptosis of renal tubular epithelial cells

3,3′-Diindolylmethane (DIM) is a naturally derived indole compound found in the Brassica family of vegetables. DIM has several beneficial effects, including anti-cancer, anti-inflammatory and anti-angiogenic functions. However, the effects of DIM on acute kidney injury (AKI) stimulated by lipopolysaccharide (LPS) are poorly studied. In this present study, male BALB/c mouse models of AKI were established using intraperitoneal injections of 10 mg/kg LPS. DIM (40 mg/kg) was administered intraperitoneally 24 and 2 h before LPS exposure. The results indicated that DIM significantly mitigated histopathological changes in the kidneys and improved the levels of blood urea nitrogen and serum creatinine. DIM also suppressed the LPS-induced production of reactive oxygen species and cell apoptosis. Furthermore, DIM treatment significantly decreased the expression of NADPH oxidase 2 (NOX2) and NOX4 in LPS-treated mice. Therefore, DIM may exert its renoprotective actions by inhibiting NOX-mediated oxidative stress and the apoptosis of renal tubular epithelial cells.

Increased expression of Toll-like receptors 2, 3, 4 and 7 mRNA in the kidney and intestine of a septic mouse model

Toll-like receptors (TLRs) are the key regulators of innate and adaptive immunity and are highly expressed during sepsis. Thus, studying the expression of TLRs in an animal septic model might indicate their possible association with acute kidney injury in sepsis. Seventy-two male C57BL/6J mice were used for this study. Randomly, these animals were divided into 6 groups (N = 12/group): 3 control and 3 septic groups depending on the euthanasia time (24 h, 48 h, 72 h). Septic groups underwent cecal ligation and puncture (CLP) to induce peritonitis, while control groups had a sham operation. Hematological tests were performed in serum for immune biomarkers; immunohistochemistry, morphometry and qRT-PCR analysis were used on both kidney and intestine tissues to evaluate the expression of TLR 2, 3, 4 and 7 in a septic process. At the end of each experimental period, we found that TLRs 2, 3, 4 and 7 were expressed in both tissues but there were differences between those at various time points. Also, we found that mRNA levels were significantly higher in qRT-PCR evaluation in septic groups than control groups in both kidney and intestinal tissues (p < 0.05); showing a steady increase in the septic groups as the time to euthanasia was prolonged (p < 0.05). Overall, our study provides a suggestion that TLRs 2, 3, 4 and 7 are highly expressed in the kidneys of septic mice and especially that these TLRs are sensitive and specific markers for sepsis. Finally, our study supports the diagnostic importance of TLRs in AKI and provides an insight on the contribution of septic mice models in the study of multi organ dysfunction syndrome in general.

Relation of neutrophil-to-lymphocyte ratio to acute kidney injury in patients with sepsis and septic shock: A retrospective study

BACKGROUND

The purpose of this study was to determine the association of the neutrophil-to-lymphocyte ratio (NLR) measured at the time of admission to intensive unit (ICU) with acute kidney injury (AKI) in patients with sepsis and septic shock. In addition, we investigated whether the NLR affects in-hospital mortality in septic AKI patients.

METHODS

In this retrospective study, a total of 222 adult patients with sepsis and septic shock were included, who were admitted to the ICU of Zhongnan Hospital of Wuhan University from January 2015 to December 2017. Sepsis and septic shock were diagnosed based on sepsis-3 consensus. AKI was diagnosed according to the KDIGO-AKI criteria. The primary outcome of the study was septic AKI. The secondary endpoint was in-hospital mortality of patients with septic AKI.

RESULTS

132 patients (59.46%) had AKI, and 64 (28.83%) died, of whom 55 (41.67%) in the AKI group and 9 (10.00%) in the non-AKI group. The NLR of the AKI group was significantly higher than that of the non-AKI group, and there was a statistically significant difference between the two groups (P < 0.001). Multivariate logistic regression analysis suggested that the NLR was independent predictors of septic AKI (OR = 1.047, 95% CI: 1.005-1.091, P = 0.026). The ROC curve showed that the AUC of the NLR for predicting septic AKI was 0.656 (95% CI 0.584-0.728, P < 0.001) and the cutoff value was 17.11 (sensitivity, 62.1%; specificity, 68.9%). However, no correlation was found between the NLR and in-hospital mortality in septic AKI patients.

CONCLUSION

NLR, a laboratory variable that is simple, widely available and inexpensive, was associated with the development of septic AKI and may be potential for risk stratification of septic AKI.

Acute kidney injury following contrast media administration in the septic patient: A retrospective propensity-matched analysis

PURPOSE

To determine the risk for acute kidney injury (AKI) attributable to intravenous contrast media (CM) administration in septic patients.

MATERIALS AND METHODS

This was a single-center retrospective propensity matched cohort analysis performed in the emergency department (ED) of an academic medical center. All visits for patients ≥18 years who met sepsis diagnostic criteria and had serum creatinine (SCr) measured both on arrival to the ED and again 48 to 72 h later were included. Of 4171 visits, 1464 patients underwent contrast-enhanced CT (CECT), 976 underwent unenhanced CT and 1731 underwent no CT at all.

RESULTS

The primary outcome was incidence of AKI. Logistic regression and between-groups odds ratios with and without propensity-score matching were used to test for an independent association between CM administration and AKI. Incidence of AKI was 7.2%, 9.4% and 9.7% in those who underwent CECT, unenhanced CT and no CT. CM administration was not associated with increased incidence of AKI.

CONCLUSIONS

Sepsis is a medical emergency proven to benefit from early diagnosis and rapid initiation of treatment, which is often aided by CECT. Our findings argue against withholding CM for fear of precipitating AKI in potentially septic patients.

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.

Protective Effect of Hesperidin Against Sepsis-Induced Lung Injury by Inducing the Heat-Stable Protein 70 (Hsp70)/Toll-Like Receptor 4 (TLR4)/ Myeloid Differentiation Primary Response 88 (MyD88) Pathway

Background

Sepsis-induced lung injury is associated with high mortality. The present investigation evaluated the protective effect of hesperidin against sepsis-induced lung injury and also postulates the possible mechanism of its action.

Material/Methods

Lung injury was induced by sepsis in all animals, in which sepsis was produced by cecal ligation and puncture (CLP). Animals were treated with hesperidin 10 and 20 mg/kg i.v. 30 min after the surgery. Oxygenation index and lung injury score were determined and levels of pro-inflammatory mediators and markers of oxidative stress were also estimated in the lung tissues. Moreover, expression of caspase-3, B-cell lymphoma (Bcl-2), Toll-like receptor 4 (TLR4), heat-stable protein 70 (Hsp70) and myeloid differentiation primary response 88 (MyD88) protein was estimated by Western blot assay and immunofluorescence assay.

Results

Hesperidin attenuated the partial pressure of arterial oxygen/fraction of inspired oxygen (PaO2/FiO2) ratio and lung injury score in CLP-induced lung injury mice. There was a significant (p<0.01) decrease in the level of pro-inflammatory mediators in the lung tissue of CLP-induced lung injury mice. Moreover, markers of oxidative stress were attenuated in the hesperidin-treated group. Treatment with hesperidin attenuated the expression of caspase-3, Bcl-2, TLR4, Hsp70, and MyD88 protein in the lung tissue of CLP-induced lung injury mice.

Conclusions

Hesperidin protects against lung injury by attenuating the Hsp70/TLR4/MyD88 pathway in CLP-induced lung injury mice.

Hypertonic saline and pentoxifylline enhance survival, reducing apoptosis and oxidative stress in a rat model of strangulated closed loop small bowel obstruction

OBJECTIVES

Intestinal obstruction has a high mortality rate when therapeutic treatment is delayed. Resuscitation in intestinal obstruction requires a large volume of fluid, and fluid combinations have been studied. Therefore, we evaluated the effects of hypertonic saline solution (HS) with pentoxifylline (PTX) on apoptosis, oxidative stress and survival rate.

METHODS

Wistar rats were subjected to intestinal obstruction and ischemia through a closed loop ligation of the terminal ileum and its vessels. After 24 hours, the necrotic bowel segment was resected, and the animals were randomized into four groups according to the following resuscitation strategies: Ringer's lactate solution (RL) (RL-32 ml/kg); RL+PTX (25 mg/kg); HS+PTX (HS, 7.5%, 4 ml/kg), and no resuscitation (IO-intestinal obstruction and ischemia). Euthanasia was performed 3 hours after resuscitation to obtain kidney and intestine samples. A malondialdehyde (MDA) assay was performed to evaluate oxidative stress, and histochemical analyses (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling [TUNEL], Bcl-2 and Bax) were conducted to evaluate kidney apoptosis. Survival was analyzed with another series of animals that were observed for 15 days.

RESULTS

PTX in combination with RL or HS reduced the MDA levels (nmol/mg of protein), as follows: kidney IO=0.42; RL=0.49; RL+PTX=0.31; HS+PTX=0.34 (p<0.05); intestine: IO=0.42; RL=0.48; RL+PTX=0.29; HS+PTX=0.26 (p<0.05). The number of labeled cells for TUNEL and Bax was lower in the HS+PTX group than in the other groups (p<0.05). The Bax/Bcl-2 ratio was lower in the HS+PTX group than in the other groups (p<0.05). The survival rate on the 15th day was higher in the HS+PTX group (77%) than in the RL+PTX group (11%).

CONCLUSION

PTX in combination with HS enhanced survival and attenuated oxidative stress and apoptosis. However, when combined with RL, PTX did not reduce apoptosis or mortality.

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.

Isoliquiritigenin attenuates LPS-induced AKI by suppression of inflammation involving NF-κB pathway

Septic acute kidney injury (AKI) characterized as acute infection and renal inflammation, still lacks of effective therapies. Isoliquiritigenin (ISL) as a small molecular from licorice, is able to inhibit the expression of HMGB1. However, the role and mechanism of ISL in septic AKI has not been investigated. In this study, we used LPS injection to induce murine septic AKI. One hour before LPS injection, 50 mg/kg ISL was once orally given to the mice. For the in vitro study, HK2 human tubular cells were respectively treated with 50 μM and 100 μM ISL 5 hrs before 2 μg/ml LPS stimulation. Then we observed that ISL ameliorated renal dysfunction and attenuated renal tubular injury. ISL inhibited the phosphorylation of IκB-α and NF-κB p65 after LPS induction both in vivo and in vitro. ISL also inhibited NF-κB p65 translocation from cytoplasm to the nucleus upon LPS stimulation. Further, NF-κB p65 translocation could trigger macrophage polarization, neutrophil activation and pro-inflammatory cytokines secretion in LPS-induced inflammation. These results showed that ISL could alleviate LPS-induced AKI by suppressing NF-κB p65 translocation and inhibiting inflammatory responses, indicating protective effects of ISL in LPS-induced acute renal inflammation. This study might be useful for designing potential clinical trials to prevent and treat sepsis induced AKI in patients with serious illness.

Preventive Leptin Administration Protects Against Sepsis Through Improving Hypotension, Tachycardia, Oxidative Stress Burst, Multiple Organ Dysfunction, and Increasing Survival

Sepsis syndrome is the most important cause of mortality in critically ill patients admitted to intensive care units (ICUs). However, current therapies for its prevention and treatment are still unsatisfactory, and the mortality rate is still high. Non-septic ICU patients are vulnerable to acquire sepsis syndrome. Thus, a preventive treatment for this population is needed. During sepsis syndrome and endotoxemia, severe hypotension, tachycardia, oxidative and immune response increase, multiple organ dysfunction syndrome (MODS) and decreased survival are observed. Leptin administration protects against negative effects of sepsis syndrome and endotoxemia. Furthermore, it is has been reported that leptin elevates blood pressure mediated by sympathetic nervous system activation. However, whether leptin administration before sepsis induction mediates its protective effects during sepsis through blood pressure regulation is not known. Therefore, we investigated whether pre-treatment of leptin improves blood pressure and MODS, resulting in survival increase during endotoxemia. The results showed that leptin administration before endotoxemia induction reduced both the hypotension and tachycardia characteristically observed during endotoxemia. Notably, this protective effect was observed early and late in the course of endotoxemia. Endotoxemia-induced MODS decreased in leptin-treated rats, which was reflected in normal values for liver and kidney function, inhibition of muscle mass wasting and maintenance of glycemia. Furthermore, leptin pre-treatment decreased the oxidative stress burst in blood and blunted the increased pro-inflammatory cytokines TNF-α, IL-1β, and IL-6 observed during endotoxemia. Remarkably, according to the leptin-induced increase in survival, leptin pre-administration decreased the risk for death associated with sepsis syndrome at early and late times after endotoxemia induction. These results show a potential preventive therapy against sepsis syndrome and endotoxemia in vulnerable patients, based in the beneficial actions of leptin.

Morbidity and Mortality of Crystalloids Compared to Colloids in Critically Ill Surgical Patients

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Background

The multicenter randomized Colloids versus Crystalloids for the Resuscitation of the Critically Ill (CRISTAL) trial was designed to test whether colloids altered mortality compared to crystalloids in the resuscitation of intensive care unit patients with hypovolemic shock. This preplanned analysis tested the same hypothesis in the subgroup of surgical patients.

Methods

The CRISTAL trial prospectively defined patients as critically ill surgical patients whenever they underwent emergency or scheduled surgery immediately before or within 24 h of intensive care unit admission and had hypovolemic shock. The primary outcome measure was death by day 28. Secondary outcome measures included death by day 90, the need for renal replacement therapy, or the need for fresh frozen plasma transfusion.

Results

There were 741 critically ill surgical patients, 356 and 385 in the crystalloid and colloid arm, respectively. Median (interquartile range) age was 66 (52 to 76) yr, and 484 (65.3%) patients were male. Surgery was unscheduled in 543 (73.3%) cases. Mortality by day 28 did not significantly differ for crystalloids 84 (23.6%) versus colloids 100 (26%; adjusted odds ratio, 0.86; 95% CI, 0.61 to 1.21; P = 0.768). Death by day 90 (111 [31.2%] vs. 122 [31.7%]; adjusted odds ratio, 0.97; 95% CI, 0.70 to 1.33; P = 0.919) did not significantly differ between groups. Renal replacement therapy was required for 42 (11.8%) patients in the crystalloids arm versus 49 (12.7%) in the colloids arm (P = 0.871).

Conclusions

The authors found no survival benefit when comparing crystalloids to colloids in critically ill surgical patients.

Protective effect of sesamin in lipopolysaccharide-induced mouse model of acute kidney injury via attenuation of oxidative stress, inflammation, and apoptosis

CONTEXT

Acute kidney injury (AKI) is considered a major public health concern in today's world. Sepsis-induced AKI is large as a result of exposure to lipopolysaccharide (LPS) that is the major outer membrane component of Gram-negative bacteria. Sesamin is the main lignan of sesame seeds with multiple protective effects.

OBJECTIVE

In this research, we tried to demonstrate the protective effect of sesamin pretreatment in LPS-induced mouse model of AKI.

METHODS

LPS was injected at a single dose of 10 mg/kg (i.p.) and sesamin was given p.o. at doses of 25, 50, or 100 mg/kg, one hour prior to LPS.

RESULTS

Treatment of LPS-challenged mice with sesamin reduced serum level of creatinine and blood urea nitrogen (BUN) and returned back renal oxidative stress-related parameters including glutathione (GSH), malondialdehyde (MDA), and activity of catalase and superoxide dismutase (SOD). Moreover, sesamin alleviated inappropriate changes of renal nuclear factor-kappaB (NF-κB), toll-like receptor 4 (TLR4), cyclooxygenase-2 (COX2), tumor necrosis factor α (TNFα), interleukin-6, DNA fragmentation (an apoptotic index), and nuclear factor (erythroid-derived 2)-like 2 (Nrf2). In addition, sesamin diminished magnitude of kidney tissue damage due to LPS.

CONCLUSION

In summary, sesamin could dose-dependently abrogate LPS-induced AKI via attenuation of renal oxidative stress, inflammation, and apoptosis.

Infection-Induced Kidney Diseases

Infection induced kidney diseases are of concern for clinicians because timely detection and treatment of infections may cure or limit the extent of injury inflicted by microorganisms causing the infections. Infections can cause kidney injury by either direct invasion, or indirectly by immune mediated mechanisms, which manifest as post-infectious glomerulonephritis, or infection-related glomerulonephritis. Clinical manifestations may be acute or chronic depending on the microorganisms, endemic/epidemic nature and source of infection. All microbials virus, bacteria, mycobacteria, fungus, and protozoa have been implicated in kidney diseases either causing direct kidney injuries or immune-mediated injuries. Infection control practices in large parts of world is limited by poverty, social behavior, high population density, deforestation, inadequate access to safe drinking water, and poor health care facilities. Although, antimicrobials and vaccinations have successfully eradicated and cured many infectious diseases; however injudicious antimicrobial use and emergence of resistant organisms complicated the disease severity like secondary renal amyloidosis with chronic persistent infection. Re-emergence of various infections has been a recent pattern in developed world leading to uncertain diagnostic challenges, and association with kidney diseases.

Methane-Rich Saline Ameliorates Sepsis-Induced Acute Kidney Injury through Anti-Inflammation, Antioxidative, and Antiapoptosis Effects by Regulating Endoplasmic Reticulum Stress

Sepsis-induced acute kidney injury (AKI) is a severe complication of sepsis and an important cause of mortality in septic patients. Previous investigations showed that methane had protective properties against different diseases in animal models. This study is aimed at investigating whether methane-rich saline (MRS) has a protective effect against sepsis-induced AKI. Sepsis was induced in wild-type C57BL/6 mice by cecal ligation and puncture (CLP), and the mice were divided into three groups: a sham control group (sham), a surgery group with saline intraperitoneal injection (i.p.) treatment (CLP + NS), and a surgery group with MRS i.p. treatment (CLP + MRS). 24 h after the establishment of the sepsis, the blood and kidney tissues of mice in all groups were collected. According to the serum levels of blood urea nitrogen (BUN) and creatinine (CRE) and a histologic analysis, which included hematoxylin-eosin (H&E) staining and periodic acid-Schiff (PAS) staining, MRS treatment protected renal function and tissues from acute injury. Additionally, MRS treatment significantly ameliorated apoptosis, based on the levels of apoptosis-related protein makers, including cleaved caspase-3 and cleaved PARP, and the levels of Bcl-2/Bax expression and TUNEL staining. In addition, the endoplasmic reticulum (ER) stress-related glucose-regulated protein 78 (GRP78)/activating transcription factor 4 (ATF4)/C/EBP homologous protein (CHOP)/caspase-12 apoptosis signaling pathway was significantly suppressed in the CLP + MRS group. The levels of inflammation and oxidative stress were also reduced after MRS treatment. These results showed that MRS has the potential to ameliorate sepsis-induced acute kidney injury through its anti-inflammatory, antioxidative, and antiapoptosis properties.

Parenteral Succinate Reduces Systemic ROS Production in Septic Rats, but It Does Not Reduce Creatinine Levels

In sepsis, reactive oxygen species (ROS) production is increased. This process takes place mainly within the electron transport chain. ROS production is part of the pathophysiology of multiple organ failure in sepsis. Succinate yields Dihydroflavine-Adenine Dinucleotide (FADH₂), which enters the chain through complex II, avoiding complex I, through which electrons are lost. The aim of this work is to determine if parenteral succinate reduces systemic ROS production and improves kidney function. Rats with cecal ligation and puncture were used as model of sepsis, and 4 groups were made: Control group; Succinate group, which only received parenteral succinate; Sepsis group; and Sepsis which received parenteral succinate. Systemic ROS are measured 24 hours after the procedure. Rats subjected to cecal puncture treated with succinate had less systemic ROS than Septic untreated rats (p = 0.007), while there were no differences in creatinine levels (p = 0.07). There was no correlation between creatinine and systemic ROS levels (p = 0.3). We concluded that parenteral succinate reduces ROS levels, but it does not reduce creatinine levels. Since there is no correlation between both levels, the processes would not be related.

Sex and mortality in septic severe acute kidney injury

PURPOSE

To investigate the relationship between sex and mortality and whether menopause or the intensity of renal replacement therapy (RRT) modify this relationship in patients with severe septic acute kidney injury (AKI).

MATERIALS AND METHODS

Post-hoc analysis of patients with sepsis included in the Randomized Evaluation of Normal versus Augmented Level renal replacement therapy (RENAL) trial.

RESULTS

Of 724 patients, 458 (63.3%) were male and 266 (36.7%) were female. The mean delivered effluent flow rate was 25.6 ± 7.4 ml/kg/h (80 ± 15% of prescribed dose) in males and 27.4 ± 7.6 ml/kg/h (83 ± 15% of prescribed dose) in females (p = .01). A total of 237 (51.7%) males and 118 (44.5%) females died within 90 days of randomization (p = .06). The adjusted hazard ratio (HR) for 90-day mortality was significantly decreased in females as compared with males (HR 0.74, 95% CI 0.57 to 0.96, p = .02). The relationship between sex and mortality was not significantly altered by menopausal status (adjusted P value for interaction 0.99) or by RRT intensity allocation (adjusted P value for interaction 0.27).

CONCLUSIONS

In a cohort of patients with sepsis and severe AKI, female sex was associated with improved survival. The relationship between sex and survival was not altered by menopausal status or RRT intensity.

Oliguria in critically ill patients: a narrative review

Oliguria is often observed in critically ill patients. However, different thresholds in urine output (UO) have raised discussion as to the clinical importance of a transiently reduced UO of less than 0.5 ml/kg/h lasting for at least 6 h. While some studies have demonstrated that isolated oliguria without a concomitant increase in serum creatinine is associated with higher mortality rates, different underlying pathophysiological mechanisms suggest varied clinical importance of reduced UO, as some episodes of oliguria may be fully reversible. We aim to explore the clinical relevance of oliguria in critically ill patients and propose a clinical pathway for the diagnostic and therapeutic management of an oliguric, critically ill patient.

Monophosphoryl lipid A prevents impairment of medullary thick ascending limb [Formula: see text] absorption and improves plasma [Formula: see text] concentration in septic mice

Metabolic acidosis is the most common acid-base disorder in septic patients and is associated with increased mortality. Previously, we demonstrated that sepsis induced by cecal ligation and puncture (CLP) impairs [Formula: see text] absorption in the medullary thick ascending limb (MTAL) by 1) decreasing the intrinsic [Formula: see text] absorptive capacity and 2) enhancing inhibition of [Formula: see text] absorption by LPS through upregulation of Toll-like receptor (TLR) 4 signaling. Both effects depend on ERK activation. Monophosphoryl lipid A (MPLA) is a detoxified TLR4 agonist that enhances innate antimicrobial immunity and improves survival following sepsis. Pretreatment of MTALs with MPLA in vitro prevents LPS inhibition of [Formula: see text] absorption. Here we examined whether pretreatment with MPLA would protect the MTAL against sepsis. Vehicle or MPLA was administered to mice 48 h before sham or CLP surgery, and MTALs were studied in vitro 18 h postsurgery. Pretreatment with MPLA prevented the effects of sepsis to decrease the basal [Formula: see text] absorption rate and enhance inhibition by LPS. These protective effects were mediated through MPLA stimulation of a Toll/IL-1 receptor domain-containing adaptor-inducing IFN-β-(TRIF)-dependent phosphatidylinositol 3-kinase-Akt pathway that prevents sepsis- and LPS-induced ERK activation. The effects of MPLA to improve MTAL [Formula: see text] absorption were associated with marked improvement in plasma [Formula: see text] concentration, supporting a role for the kidneys in the pathogenesis of sepsis-induced metabolic acidosis. These studies support detoxified TLR4-based immunomodulators, such as MPLA, that enhance antimicrobial responses as a safe and effective approach to prevent or treat sepsis-induced renal tubule dysfunction and identify cell signaling pathways that can be targeted to preserve MTAL [Formula: see text] absorption and attenuate metabolic acidosis during sepsis.

Urine electrolyte measurement as a "window" into renal microcirculatory stress assessment in critically ill patients

Urine electrolyte assessment has long been used in order to understand electrolyte concentration disturbances in blood and as an easy tool for monitoring renal perfusion and structural tubular damage. In the last few years, great improvement in the pathophysiology of acute kidney injury (AKI) has occurred, and the correlation between urine biochemistry (UB) behavior and renal perfusion was frequently questioned. Many authors have suggested abandoning UB monitoring due to its unclear role in AKI monitoring. Our group has been working in this field in the critically ill population, and we believe that, although UB is indeed very useful, a different point of view regarding the interpretation of the data should be used. The aim of this review is to explain the rationale of these new concepts and make suggestions for their adequate use in daily ICU practice, especially in low-income countries where more sophisticated and expensive AKI biomarker assessments are not available.

RIPK3 promotes sepsis-induced acute kidney injury via mitochondrial dysfunction

Sepsis causes acute kidney injury (AKI) in critically ill patients, although the pathophysiology remains unclear. The receptor-interacting protein kinase-3 (RIPK3), a cardinal regulator of necroptosis, has recently been implicated in the pathogenesis of human disease. In mice subjected to polymicrobial sepsis, we demonstrate that RIPK3 promotes sepsis-induced AKI. Utilizing genetic deletion and biochemical approaches in vitro and in vivo, we identify a potentially novel pathway by which RIPK3 aggravates kidney tubular injury independently of the classical mixed lineage kinase domain-like protein-dependent (MLKL-dependent) necroptosis pathway. In kidney tubular epithelial cells, we show that RIPK3 promotes oxidative stress and mitochondrial dysfunction involving upregulation of NADPH oxidase-4 (NOX4) and inhibition of mitochondrial complex I and -III, and that RIPK3 and NOX4 are critical for kidney tubular injury in vivo. Furthermore, we demonstrate that RIPK3 is required for increased mitochondrial translocation of NOX4 in response to proinflammatory stimuli, by a mechanism involving protein-protein interactions. Finally, we observed elevated urinary and plasma RIPK3 levels in human patients with sepsis-induced AKI, representing potential markers of this condition. In conclusion, we identify a pathway by which RIPK3 promotes kidney tubular injury via mitochondrial dysfunction, independently of MLKL, which may represent a promising therapeutic target in sepsis-induced AKI.

Septic acute kidney injury patients in emergency department: The risk factors and its correlation to serum lactate

BACKGROUND

Acute kidney injury (AKI) is a common complication in septic patients, imposing a heavy burden of illness in terms of morbidity and mortality. Serum lactate is a widely used marker predicting the severity of sepsis. A paucity of research has investigated septic AKI in emergency departments (EDs) and its correlation with initial serum lactate level. This study aimed at identifying risk factors for septic AKI and clarifying the link between initial serum lactate level and septic AKI in ED patients.

METHODS

A retrospective cohort study was conducted at a single tertiary referral medical center. The medical records of all adult ED patients with measurement of serum lactate and creatinine between January 2012 and December 2016 were reviewed. A total of 696 septic patients were stratified into AKI and non-AKI groups according to Acute Kidney Injury Network (AKIN) criteria for further statistical analysis.

RESULTS

Ninety-nine septic patients (14.2%) had AKI, with AKIN-I, AKIN-II, and AKIN-III in 71.7%, 11.1%, and 17.2% of patients, respectively. Compared with the non-AKI group, the AKI group had a significantly higher mortality rate (71.7% vs. 21.3%, p < 0.001). Independent risk factors for septic AKI included liver disease (adjusted odds ratio [AOR] = 2.02, 95% confidence interval [CI] = 1.16-3.52), diabetes mellitus (AOR = 1.73, 95% CI = 1.11-2.69), chronic kidney disease (AOR = 1.68, 95% CI = 1.06-2.66), and initial serum lactate (AOR = 1.08, 95% CI = 1.02-1.14).

CONCLUSIONS

Patients with septic AKI had an overwhelmingly higher mortality rate. The comorbidities of liver disease, diabetes mellitus, and chronic kidney disease were correlated with septic AKI and in combination with an elevated initial serum lactate level had predictive regarding AKI and further mortality in ED septic patients.

In vitro comparison of the adsorption of inflammatory mediators by blood purification devices

Background

Septic shock, a leading cause of acute kidney injury, induces release of pro-/anti-inflammatory mediators, leading to increased mortality and poor renal recovery. This is the first in vitro study directly comparing three single-use blood purification devices in terms of removing sepsis-associated mediators and endotoxins.

Methods

In vitro hemoperfusion was performed using oXiris^®, CytoSorb^®, and Toraymyxin^®. Heparinized human plasma from healthy volunteers was pre-incubated with pathologic quantities of inflammatory mediators and filtered in a closed-loop circulation model for 2 h. For each device, the removal of 27 inflammatory mediators was measured over time. Endotoxin removal mediated by oXiris and Toraymyxin was assessed using hemoperfusion over 6 h.

Results

Endotoxin (lipopolysaccharide) removal was most rapid with Toraymyxin; mean adsorptive clearance over the first 30 min was ~ 20 ml/min vs ~ 8 ml/min with oXiris (p < 0.05). There was minimal endotoxin removal with CytoSorb (1 ml/min). At 120 min, there was no significant difference between the endotoxin removal rates using oXiris (mean ± standard deviation, 68.0 ± 4.4%) and Toraymyxin (83.4 ± 3.8%); both were significantly higher vs CytoSorb (− 6.3 ± 4.9%; p < 0.05). Total removal with oXiris was 6.9 μg vs 9.7 μg for Toraymyxin, where the total lipopolysaccharide quantity introduced was approximately 15.8 μg. Removal rates of pro-/anti-inflammatory cytokines and other inflammatory mediators were similar between oXiris and CytoSorb and were higher with CytoSorb and oXiris vs Toraymyxin. Granulocyte colony-stimulating factor was only effectively adsorbed by CytoSorb (99.4%). Differences were detected between the adsorption mechanism of the devices; binding to oXiris was mainly ionic, while CytoSorb was hydrophobic. No specific protein adsorption was found qualitatively with Toraymyxin.

Conclusions

Adsorption rate kinetics varied for individual inflammatory mediators using the three blood purification devices. Mechanisms of adsorption differed between the devices. oXiris was the only device tested that showed both endotoxin and cytokine removal. oXiris showed similar endotoxin adsorption to Toraymyxin and similar adsorption to CytoSorb for the removal of other inflammatory mediators. Differences in device removal capacities could enable treatment to be more tailored to patients.

Electronic supplementary material

The online version of this article (10.1186/s40635-018-0177-2) contains supplementary material, which is available to authorized users.

Sepsis-induced acute kidney injury

PURPOSE OF REVIEW

Sepsis is a common and frequently fatal condition in which mortality has been consistently linked to increasing organ dysfunction. For example, acute kidney injury (AKI) occurs in 40-50% of septic patients and increases mortality six to eight-fold. However, the mechanisms by which sepsis causes organ dysfunction are not well understood and hence current therapy remains reactive and nonspecific.

RECENT FINDINGS

Recent studies have challenged the previous notion that organ dysfunction is solely secondary to hypoperfusion, by showing, for example, that AKI occurs in the setting of normal or increased renal blood flow; and that it is characterized not by acute tubular necrosis or apoptosis, but rather by heterogeneous areas of colocalized sluggish peritubular blood flow and tubular epithelial cell oxidative stress. Evidence has also shown that microvascular dysfunction, inflammation, and the metabolic response to inflammatory injury are fundamental pathophysiologic mechanisms that may explain the development of sepsis-induced AKI.

SUMMARY

The implications of these findings are significant because in the context of decades of negative clinical trials in the field, the recognition that other mechanisms are at play opens the possibility to better understand the processes of injury and repair, and provides an invaluable opportunity to design mechanism-targeted therapeutic interventions.

Biomarkers of Sepsis-Induced Acute Kidney Injury

Sepsis, an infection-induced systemic disease, leads to pathological, physiological, and biochemical abnormalities in the body. Organ dysfunction is caused by a dysregulated host response to infection during sepsis which is a major contributing factor to acute kidney injury (AKI) and the mortality rate for sepsis doubles due to coincidence of AKI. Sepsis-induced AKI is strongly associated with increased mortality and other adverse outcomes. More timely diagnosis would allow for earlier intervention and could improve patient outcomes. Sepsis-induced AKI is characterized by a distinct pathophysiology compared with other diseases and may also have unique patterns of plasma and urinary biomarkers. This concise review summarizes properties and perspectives of the biomarkers for their individual clinical utilization.