0.9% saline versus Plasma-Lyte as initial fluid in children with diabetic ketoacidosis (SPinK trial): a double-blind randomized controlled trial

BACKGROUND

Acute kidney injury (AKI) is an important complication encountered during the course of diabetic ketoacidosis (DKA). Plasma-Lyte with lower chloride concentration than saline has been shown to be associated with reduced incidence of AKI in adults with septic shock. No study has compared this in DKA.

METHODS

This double-blind, parallel-arm, investigator-initiated, randomized controlled trial compared 0.9% saline with Plasma-Lyte-A as initial fluid in pediatric DKA. The study was done in a tertiary care, teaching, and referral hospital in India in children (> 1 month-12 years) with DKA as defined by ISPAD. Children with cerebral edema or known chronic kidney/liver disease or who had received pre-referral fluids and/or insulin were excluded. Sixty-six children were randomized to receive either Plasma-Lyte (n = 34) or 0.9% saline (n = 32).

MAIN OUTCOMES

Primary outcome was incidence of new or progressive AKI, defined as a composite outcome of change in creatinine (defined by KDIGO), estimated creatinine clearance (defined by p-RIFLE), and NGAL levels. The secondary outcomes were resolution of AKI, time to resolution of DKA (pH > 7.3, bicarbonate> 15 mEq/L & normal sensorium), change in chloride, pH and bicarbonate levels, proportion of in-hospital all-cause mortality, need for renal replacement therapy (RRT), and length of ICU and hospital stay.

RESULTS

Baseline characteristics were similar in both groups. The incidence of new or progressive AKI was similar in both [Plasma-Lyte 13 (38.2%) versus 0.9% saline 15 (46.9%); adjusted OR 1.22; 95% CI 0.43-3.43, p = 0.70]. The median (IQR) time to resolution of DKA in Plasma-Lyte-A and 0.9% saline were 14.5 (12 to 20) and 16 (8 to 20) h respectively. Time to resolution of AKI was similar in both [Plasma-Lyte 22.1 versus 0.9% saline 18.8 h (adjusted HR 1.72; 95% CI 0.83-3.57; p = 0.14)]. Length of hospital stay was also similar in both [Plasma-Lyte 9 (8 to 12) versus 0.9% saline 10 (8.25 to 11) days; p = 0.39].

CONCLUSIONS

The incidence of new or progressive AKI and resolution of AKI were similar in both groups. Plasma-Lyte-A was similar to 0.9% Saline in time to resolution of DKA, need for RRT, mortality, and lengths of PICU and hospital stay.

TRIAL REGISTRATION

Clinical trial registry of India, CTRI/2018/05/014042 (ctri.nic.in) (Retrospectively registered).

Oxidative stress and autophagy: crucial modulators of kidney injury

Both acute kidney injury (AKI) and chronic kidney disease (CKD) that lead to diminished kidney function are interdependent risk factors for increased mortality. If untreated over time, end stage renal disease (ESRD) is an inevitable outcome. Acute and chronic kidney diseases occur partly due to imbalance between the molecular mechanisms that govern oxidative stress, inflammation, autophagy and cell death. Oxidative stress refers to the cumulative effects of highly reactive oxidizing molecules that cause cellular damage. Autophagy removes damaged organelles, protein aggregates and pathogens by recruiting these substrates into double membrane vesicles called autophagosomes which subsequently fuse with lysosomes. Mounting evidence suggests that both oxidative stress and autophagy are significantly involved in kidney health and disease. However, very little is known about the signaling processes that link them. This review is focused on understanding the role of oxidative stress and autophagy in kidney diseases. In this review, we also discuss the potential relationships between oxidative stress and autophagy that may enable the development of better therapeutic intervention to halt the progression of kidney disease and promote its repair and resolution.

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The molecular mechanisms underlying the regulation of oxidative stress responses and autophagy may exhibit considerable cross-talk.

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The autophagy pathway may be regulated in the context of kidney diseases. Failure or disruption of the autophagy pathway may contribute to the pathogenesis of kidney diseases.

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Targeting the autophagy pathway may show considerable therapeutic potential in the treatment and management of kidney disorders.

Resveratrol attenuates lipopolysaccharide-induced acute kidney injury by suppressing inflammation driven by macrophages

SCOPE

Acute kidney injury (AKI) is the most frequent and serious complication in sepsis, a potentially deadly inflammatory response induced by bacterial, viral, or fungal infection. LPS-induced AKI is associated with an abnormal inflammatory response, including renal endothelial dysfunction and renal inflammation. Resveratrol, a natural phytoalexin with low toxicity and anti-inflammatory properties, is known to protect endothelial cells and modulate the immune response in sepsis.

METHODS AND RESULTS

This study investigates the potential protective effects of resveratrol on AKI induced by LPS exposure of mice. Resveratrol was administered as a pre- and posttreatment, or as a posttreatment alone following LPS injection and compared to control groups. Resveratrol significantly improved kidney function and lowered serum and kidney tissue inflammatory cytokine levels. Consistently, resveratrol prevented endotoxin-induced disruption of endothelial cell permeability and inhibited inflammation of kidney tissue. Resveratrol treatment attenuated the effects of LPS on macrophages, with significant inhibition of activation, cytokine release, and Toll-like receptor 4 activation. Resveratrol treatment also resulted in decreased expression of iNOS, Bcl-2, and Bcl-xL in macrophages, which was linked with induction of apoptosis in macrophages.

CONCLUSION

Our studies suggest that resveratrol might represent a novel therapeutic agent to prevent and treat sepsis-induced AKI.

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

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

SIGNIFICANCE

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

The dose-related effects of dexmedetomidine on renal functions and serum neutrophil gelatinase-associated lipocalin values after coronary artery bypass grafting: a randomized, triple-blind, placebo-controlled study

OBJECTIVES

Acute kidney failure after coronary artery bypass grafting (CABG) is a serious complication that increases morbidity and mortality rates. Early detection and prevention of this complication are very important. A novel biomarker named neutrophil gelatinase-associated lipocalin (NGAL) can play an important role in early diagnosis of acute kidney injury. Recent studies on the favourable effects of Dexmedetomidine on cardiac surgery have been published. The aim of this study is to investigate whether there is a dose-dependent positive effect of Dexmedetomidine on neutrophil gelatinase-associated lipocalin levels and renal functions when used after CABG.

METHODS

Our randomized, triple-blinded, placebo-controlled study was conducted among 295 patients scheduled for CABG surgery between August 2009 and March 2011 in a tertiary cardiac and vascular surgery clinic. A total of 90 consecutive patients who met inclusion criteria were randomized and divided into three groups. The first group received a placebo. The second and the third groups received 4 and 8 µg/cc concentration of the Dexmedetomidine infusion, respectively. Infusion rates were regulated to obtain sedation with a Ramsey sedation score of 2 or 3. Patients were regrouped according to the total Dexmedetomidine dose. Statistical analyses of variables including serum neutrophil gelatinase-associated lipocalin values and conventional renal function tests were made for all six possibilities before the blind was broken.

RESULTS

Results of conventional renal function tests were not significantly different. However, neutrophil gelatinase-associated lipocalin levels for the first postoperative day for placebo, low-dose and high-dose Dexmedetomidine groups were 176.8 ± 145.9, 97.7 ± 63.4 and 67.3 ± 10.9 ng/ml, respectively. These values were significantly different among the groups (P <0.001).

CONCLUSIONS

In our study, we found that Dexmedetomidine infusion for sedation after CABG under cardiopulmonary bypass can be useful in the prevention of kidney injury. Conventional renal function tests, including blood urea nitrogen, serum creatinine, urine output and creatinine clearance rate measurements typically may not detect the development of acute kidney dysfunction in the first 48-h postoperative period. Differences were detected in renal function in the early postoperative period and the development of acute kidney injury, as determined by measurements of blood NGAL levels, was significant and dose-dependent.

Persistent increase in mitochondrial superoxide mediates cisplatin-induced chronic kidney disease

Severe and recurrent cisplatin-induced acute kidney injury (AKI) as part of standard cancer therapy is a known risk factor for development of chronic kidney disease (CKD). The specific role of superoxide (O₂^•-)-mediated disruption of mitochondrial oxidative metabolism in CKD after cisplatin treatment is unexplored. Cisplatin is typically administered in weekly or tri-weekly cycles as part of standard cancer therapy. To investigate the role of O₂^•- in predisposing patients to future renal injury and in CKD, mice were treated with cisplatin and a mitochondrial-specific, superoxide dismutase (SOD) mimetic, GC4419. Renal function, biomarkers of oxidative stress, mitochondrial oxidative metabolism, and kidney injury markers, as well as renal histology, were assessed to evaluate the cellular changes that occur one week and one month (CKD phase) after the cisplatin insult. Cisplatin treatment resulted in persistent upregulation of kidney injury markers, increased steady-state levels of O₂^•-, increased O₂^•--mediated renal tubules damage, and upregulation of mitochondrial electron transport chain (ETC) complex I activity both one week and one month following cisplatin treatment. Treatment with a novel, clinically relevant, small-molecule superoxide dismutase (SOD) mimetic, GC4419, restored mitochondrial ETC complex I activity to control levels without affecting complexes II–IV activity, as well as ameliorated cisplatin-induced kidney injury. These data support the hypothesis that increased mitochondrial O₂^•- following cisplatin administration, as a result of disruptions of mitochondrial metabolism, may be an important contributor to both AKI and CKD progression.

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Cisplatin-induced AKI and CKD have a negative impact in long-term renal function.

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Cisplatin-induced CKD disrupts mitochondrial metabolism and increases O₂^•- levels.

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SOD mimetic, GC4419 mitigates renal damage and mitochondrial metabolism disruptions.

Serial assessment of spot urine sodium predicts effectiveness of decongestion and outcome in patients with acute heart failure

AIMS

The clinical significance of the measurement of urine sodium concentration (UNa⁺ ) in response to loop diuretic administration in patients with acute heart failure (AHF) is still unsettled. We studied the association of serial measurements of spot UNa⁺ during the first 48 h of AHF treatment with the indices of decongestion, renal function, and prognosis.

METHODS AND RESULTS

We enrolled 111 AHF patients, all of whom received intravenous furosemide on admission. The mean spot UNa⁺ significantly increased in the 6 h sample (P < 0.05 vs. baseline) and returned to baseline values in the 24 and 48 h samples. Based on the increase or decrease/no change of UNa⁺ in the 6 and 48 h samples vs. baseline, patients were divided into two groups at each time point, respectively. Patients did not differ in baseline clinical and laboratory characteristics. Patients with a decrease/no change of UNa⁺ in the 6 and 48 h samples had a lower weight loss during hospitalization. Patients with a decrease/no change of UNa⁺ in the 48 h sample had a poorer diuretic response and a significant increase in the urinary levels of the tubular biomarkers: kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin. Low UNa⁺ and decrease/no change in UNa⁺ in the 6 and 48 h samples were independent predictors of higher risk of all-cause mortality during 1-year follow-up (all P < 0.05).

CONCLUSION

In AHF, low spot UNa+ and lack to increase UNa⁺ in response to intravenous diuretics are associated with poor diuretic response, markers of tubular injury and high risk of 1-year mortality.

The role of short-chain fatty acids in kidney injury induced by gut-derived inflammatory response

It has been found that several circulating metabolites derived from gut microbiota fermentation associate with a systemic immuno-inflammatory response and kidney injury, which has been coined the gut-kidney axis. Recent evidence has suggested that short-chain fatty acids (SCFAs), which are primarily originated from fermentation of dietary fiber in the gut, play an important role in regulation of immunity, blood pressure, glucose and lipid metabolism, and seem to be the link between microbiota and host homeostasis. In addition to their important role as fuel for colonic epithelial cells, SCFAs also modulate different cell signal transduction processes via G-protein coupled receptors, and act as epigenetic regulators by the inhibition of histone deacetylase and as potential mediators involved in the autophagy pathway. Though controversial, an intimate connection between SCFAs and kidney injury has been revealed, suggesting that SCFAs may act as new therapeutic targets of kidney injury. This review is intended to provide an overview of the impact of SCFAs and the potential link to kidney injury induced by gut-derived inflammatory response.

Eriodictyol attenuates cisplatin-induced kidney injury by inhibiting oxidative stress and inflammation

Eriodictyol, a flavonoid present in citrus fruits, has been reported to have antioxidant and anti-inflammatory effects. In this study, the protective effects of eriodictyol on cisplatin (CP)-induced kidney injury were detected. CP-induced kidney injury model was established by administration of CP (20mg/kg). The results showed that treatment of eriodictyol inhibited the production of blood urea nitrogen (BUN), creatinine, MDA, TBARS, reactive oxygen species (ROS), as well as the production of TNF-α, and IL-1β in kidney tissues induced by CP. Eriodictyol also up-regulated the activities of SOD, CAT, and GSH-PX decreased by CP. Furthermore, eriodictyol was found to up-regulate the expression of Nrf2/HO-1 and inhibited CP-induced NF-κB activation in kidney tissues. In conclusion, eriodictyol protected against CP-induced kidney injury through activating Nrf2 and inhibiting NF-κB activation.

Evaluation of heat stress and cumulative incidence of acute kidney injury in sugarcane workers in Guatemala

OBJECTIVE

Agricultural workers worldwide exposed to heat stress could be at the risk of kidney injury, which could lead to chronic kidney disease of an unknown origin (CKDu). Hydration has been promoted as a key measure to reduce kidney injury. In the presence of a hydration intervention, the incidence of acute kidney injury (AKI) was calculated in a sugarcane worker population in Guatemala and several risk factors were evaluated.

METHODS

We measured kidney function at the beginning and end of the work shift at three time points in 517 sugarcane workers. We defined AKI as an increase in serum creatinine of 26.5 µmol/L or 50% or more from the pre-shift value. Associations between AKI and risk factors were examined, including interactions with hydration status.

RESULTS

The prevalence of dehydration post-shift (> 1.020 specific gravity) was 11% in February, 9% in March, and 6% in April. Cumulative incidence of AKI was 53% in February, 54% in March, and 51% in April. AKI was associated with increasing post-shift specific gravity, a dehydration marker, (OR 1.24, 95% CI 1.02-1.52) and with lower electrolyte solution intake (OR 0.94, 95% CI 0.89-0.99).

CONCLUSIONS

Dehydration and insufficient electrolyte consumption are risk factors for AKI. However even well-hydrated sugarcane workers routinely experience AKI. While hydration is important and protective, there is a need to understand other contributors to risk of AKI and identify prevention strategies with these workers.

Differential effect of quercetin on cisplatin-induced toxicity in kidney and tumor tissues

Strategies to minimize the nephrotoxicity of platinated antineoplastics without affecting its antitumour efficacy are strongly necessary to improve the pharmacotoxicological profile of these drugs. The natural flavonoid quercetin has been shown to afford nephroprotection without affecting cisplatin antitumour effect. The purpose of the present study has been to assess the differential mechanisms of action of cisplatin and quercetin on kidney and tumour tissues that could explain these effects. Wistar rats bearing subcutaneous tumours were treated with cisplatin and quercetin (and the appropriate controls). Tumour size and renal function evolution was monitored during 6 days. Platinum and quercetin content were also determined in both tissues. All the parameters studied, including blood supply, inflammation, apoptosis, critical MAPK signaling and oxidative stress in the cisplatin-treated animals are almost normalized by quercetin in the kidneys, but unaffected in the tumours. Our results suggest that in a cancer model in vivo, the protection exerted by quercetin on cisplatin nephrotoxicity is related to its antioxidant, vascular, anti-inflammatory and antiapoptotic effects, but these properties do not affect the mechanisms responsible for the antitumour effect of cisplatin.

Megalin, a multi-ligand endocytic receptor, and its participation in renal function and diseases: A review

The endocytosis mechanism is a complicated system that is essential for cell signaling and survival. Megalin, a membrane-associated endocytic receptor, and its related proteins such as cubilin, the neonatal Fc receptor for IgG, and NaPi-IIa are important in receptors-mediated endocytosis. Physiologically, megalin uptakes plasma vitamins and proteins from primary urine, preventing their loss. It also facilitates tubular retrieval of solutes and endogenous components that may be involved in modulation and recovery from kidney injuries. Moreover, megalin is responsible for endocytosis of xenobiotics and drugs in renal tubules, increasing their half-life and/or their toxicity. Fluctuations in megalin expression and/or functionality due to changes in its regulatory mechanisms are associated with some sort of kidney injury. Also, it's an important component of several pathological conditions, including diabetic nephropathy and Dent disease. Thus, exploring the fundamental role of megalin in the kidney might help in the protection and/or treatment of multiple kidney-related diseases. Hence, this review aimed to explore the physiological roles of megalin in the kidney and their implications for kidney-related injuries.

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

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

Aging-related renal injury and inflammation are associated with downregulation of Klotho and induction of RIG-I/NF-κB signaling pathway in senescence-accelerated mice

BACKGROUND AND AIMS

The predominant distribution of the antiaging Klotho protein in both the kidneys and brain may point to its essential role in protecting against dysfunction of the kidney-brain axis during the aging process. Our previous study showed that the downregulation of Klotho was involved in aging-related cognitive impairment in aged senescence-accelerated mouse prone-8 (SAMP8) mice. The present study investigated the potential role of Klotho in aging-associated inflammation and renal injury.

METHODS

Age- and gender-matched groups of SAMP8 mice and their corresponding normal control senescence-accelerated mouse resistant-1 (SAMR1) were used to investigate the potential role of Klotho in aging-associated inflammation and renal injury.

RESULTS

Compared with aged SAMR1 controls, early-stage chronic kidney disease (CKD), which is associated with an increase in the urinary albumin-to-creatinine ratio, inflammatory cell infiltration, glomerulosclerosis, and tubulointerstitial fibrosis, was observed in aged SAMP8 mice. Furthermore, the aging-related loss of Klotho-induced activation of the retinoic acid-inducible gene 1/nuclear factor-κB (RIG-I/NF-κB) signaling pathway and subsequent production of the proinflammatory mediators tumor necrosis factor α, interleukin-6, and inducible nitric oxide synthase in the kidneys of aged SAMP8 mice compared with SAMR1 controls.

CONCLUSIONS

The present results suggest that aging-related inflammation and the development of early-stage CKD are likely associated with the downregulation of Klotho and induction of the RIG-I/NF-κB signaling pathway in 12-month-old SAMP8 mice. Moreover, aged SAMP8 mice with cognitive deficits and renal damage may be a potential mouse model for investigating the kidney-brain axis in the aging process.

Protection of diabetes-induced kidney injury by phosphocreatine via the regulation of ERK/Nrf2/HO-1 signaling pathway

Diabetic nephropathy is the most common long-term complication of diabetes mellitus. The Methylglyoxal (MGO) production is mainly by metabolic pathways, such as lipolysis and glycolysis, its increases in the DM enhances oxidative stress and plays a crucial role in the diabetic nephrotic pathogenesis. Phosphocreatine (PCr) can improve lipopolysaccharide, ox-LDL-induced atherosclerosis, and alleviate vascular endothelial cell injury in diabetes. The aim of our present study is to examine the potential role of phosphocreatine (PCr) as a molecule protects against diabetes-induced Kidney Injury in-vitro and in-vivo through ERK/Nrf2/HO-1 signaling pathway. NRK-52E cells treatment with PCr obviously suppressed MGO-induced change of viability, apoptosis, coupled with decreased Bax/Bcl-2ratio, casapse-9 and caspase-3expressions. We determined the generation of reactive oxygen species (ROS) using membrane permeable fluorescent probe DCFH-DA as well as intracellular calcium by flow cytometry. ERK, Nrf2 and HO-1 expressions were determined by Western blot. PCr pretreatment significantly returned the oxidative stress enzymes to normal condition in-vitro and in-vivo. PCr pretreatment significantly reduced apoptosis, calcium and ROS production, induced by MGO, in NRK-52E cells. Moreover, pretreatment with PCr significantly inhibited cleaved caspase-3, cleaved caspase-9 and p-ERK expressions, while increased Nrf-2 and HO-1 expressions. Furthermore, PCr pretreatment significantly decreased p-ERK expression of MGO-induced injury in NRK-52E cells transfected with p-ERK cDNA. In conclusion, the renal protective effect of PCr in-vitro and in-vivo depends on suppressing apoptosis and ROS generation through ERK mediated Nrf-2/HO-1 pathway, suggesting that PCr may be a novel therapeutic candidate for the diabetic nephropathy treatment.

Protective effects of exogenous β-hydroxybutyrate on paraquat toxicity in rat kidney

In this study, we demonstrated the protective effects of β-hydroxybutyrate (β-HB) against paraquat (PQ)-induced kidney injury and elucidated the underlying molecular mechanisms. By histological examination and renal dysfunction specific markers (serum BUN and creatinine) assay, β-HB could protect the PQ-induced kidney injury in rat. PQ-induced kidney injury is associated with oxidative stress, which was measured by increased lipid peroxidation (MDA) and decreased intracellular anti-oxidative abilities (SOD, CAT and GSH). β-HB pretreatment significantly attenuated that. Caspase-mediated apoptosis pathway contributed importantly to PQ toxicity, as revealed by the activation of caspase-9/-3, cleavage of PARP, and regulation of Bcl-2 and Bax, which were also effectively blocked by β-HB. Moreover, treatment of PQ strongly decreased the nuclear Nrf2 levels. However, pre-treatment with β-HB effectively suppressed this action of PQ. This may imply the important role of β-HB on Nrf2 pathway. Taken together, this study provides a novel finding that β-HB has a renoprotective ability against paraquat-induced kidney injury.

LncRNA HOX transcript antisense RNA accelerated kidney injury induced by urine-derived sepsis through the miR-22/high mobility group box 1 pathway

OBJECTIVE

This study investigated the role of long noncoding RNA (lncRNA) HOX transcript antisense RNA (HOTAIR) in kidney injury induced by urine-derived sepsis (US).

MATERIALS AND METHODS

An Escherichia coli suspension was injected into the distal ureter of adult male Sprague Dawley rats to establish a US model. Lipopolysaccharides (LPSs) were used to induce an in vitro septic model. The interaction between HOTAIR and microRNA 22 (miR-22) was detected by RNA precipitation and RNA pull-down assays. The expression of HOTAIR, miR-22, and high mobility group box 1 (HMGB1) were detected by quantitative real time polymerase chain reaction (qRT-PCR) and Western blot analyses.

RESULTS

Compared with a sham group, HOTAIR was upregulated in kidney tissues of the US group. HOTAIR was also upregulated in LPS-induced human renal tubular epithelial cells (HK-2). Furthermore, HOTAIR negatively regulated miR-22 and promoted apoptosis of HK-2 cells. HOTAIR also promoted HMGB1 expression and HK-2 cell apoptosis by inhibiting miR-22. In addition, the miR-22/HMGB1 pathway was involved in LPS-induced HK-2 cell apoptosis. In vivo experiments showed that HOTAIR negatively modulated miR-22 and positively modulated HMGB1 and that HOTAIR knockdown decreased renal function indicators (blood urea nitrogen [BUN] and serum creatinine).

CONCLUSION

HOTAIR was upregulated in sepsis-induced kidney injury, which promoted HK-2 cell apoptosis in kidney injury through the miR-22/HMGB1 pathway.

Kidney disease and COVID-19 disease severity-systematic review and meta-analysis

We aimed to identify prevalence and association of comorbid chronic kidney disease (CKD), acute kidney injury (AKI) and utilization prevalence of continuous renal replacement therapy (CRRT) in COVID-19-hospitalized patients as a function of severity status. With the ongoing struggle across the globe to combat COVID-19 disease, published literature has described the role of kidney disease in COVID-19 patients based on single/multicenter experiences across the globe. We extracted data from observational studies describing comorbid CKD, AKI and CRRT and outcomes and severity of COVID-19-hospitalized patients from December 1, 2019-August 20, 2020 following PRISMA guidelines. Severity of COVID-19 includes intensive care unit admission, oxygen saturation < 90%, invasive mechanical ventilation utilization, in-hospital admission and mortality. Meta-analysis was performed using a random-effects model to calculate pooled estimates, and forest plots were created. In total, 29 studies with 15,017 confirmed COVID-19 patients were included. The overall prevalence of AKI was 11.6% [(430/3693)], comorbid CKD 9.7% [(1342/13,728)] and CRRT 2.58% [(102/3946)] in our meta-analysis. We also found higher odds of comorbid CKD (pooled OR: 1.70; 95%CI: 1.21-2.40; p = 0.002), AKI (8.28; 4.42-15.52; p < 0.00001) and utilization of CRRT (16.90; 9.00-31.74; p < 0.00001) in patients with severe COVID-19 disease. Conclusion Our meta-analysis suggests that comorbid CKD, AKI and utilization of CRRT were significantly associated with COVID-19 disease severity. Clinicians should focus on early triaging of COVID-19 patients with comorbid CKD and at risk for AKI to prevent complication and mortality.

Di (2-ethyl hexyl) phthalate (DEHP)-induced kidney injury in quail (Coturnix japonica) via inhibiting HSF1/HSF3-dependent heat shock response

Di (2-ethyl hexyl) phthalate (DEHP) as a plasticizer can leach away from the plastic and hence entrances into the animal food chain which caused serious hazard in organs of animals, but there are few studies on DEHP kidney toxicity. The heat-shock response (HSR) consisting of the HSPs and HSFs plays an important role in various toxicity stress conditions. To investigate the influence on kidney toxicity and the modulation of HSR during DEHP exposure, female quail were fed the diet with 0, 250, 500 and 750 mg/kg DEHP by gavage administration for 45 days. The shrinkages of glomeruli and dilation of kidney tubule epithelia cells were observed in the kidney of DEHP-exposed quail. DEHP treatment could significantly decrease the expressions of HSP25, HSP27, HSP47, HSP60, while the expressions of HSP10, HSP40, HSP70, HSP90, HSP110 were upregulated in the kidney. In addition, the expression levels of HSF1 and HSF3 were significantly increased under DEHP. This is the first study to demonstrate quail exposure to DEHP is in fact detrimental to bird kidney. Besides, DEHP could attack HSR by affecting the synthesis of HSFs to mediate the transcription of the HSPs resulting in kidney damage.

High doses of baicalin induces kidney injury and fibrosis through regulating TGF-β/Smad signaling pathway

Baicalin is a major flavonoid compound purified from Scutellariae radix, which has been described as an herb in the Chinese Pharmacopoeia. Previous studies have suggested baicalin possessed extensive anti-inflammatory, anti-cancer, anti-viral properties. However, up to known, there have been no reports of safety and toxicity in the rats following oral administration of baicalin. In this present study, we showed the first evidence that treatment of baicalin (400, 800 and 1600mg/kg/day) induced significantly kidney injury and fibrosis. The collagen synthesis and fibrosis-related protein expression were increased in the kidney of Sprague-Dawley (SD) rats after treatment with high doses of baicalin. We further investigated the potential molecular mechanism of baicalin-mediated renal fibrosis and revealed that baicalin activated the transforming growth factor-β (TGF-β)/Smad signaling pathway in a dose-dependent manner. Moreover, we also observed that baicalin induced Smad3 interaction with transcriptional coactivator p300 accompanying with increment of Smad3 acetylation. Our results may contribute to better understanding of the future pharmacological and toxicological studies of Scutellaria baicalensis Georgi and its active compounds on the human disease.

Interrelationship of environmental melamine exposure, biomarkers of oxidative stress and early kidney injury

Melamine contamination has remained pervasive in the environment even after the 2008 toxic milk scandal. Exposure to chronic low dosages of melamine is known to induce renal tubular damage, increasing the risk of stone formation and early kidney injury. This damage may come about via increased oxidative stress, but no studies of this possibility have been performed in humans. We conducted two human studies in 80 workers from melamine tableware factories (melamine workers) and 309 adult patients with calcium urolithiasis (stone patients) to evaluate the relationships between urinary melamine levels and two urinary biomarkers of oxidative stress, 8-oxo-2'-deoxyguanosine (8-OHdG) and malondialdehyde (MDA). Both human studies showed urinary melamine levels to be significantly and positively correlated with urinary 8-OHdG and MDA, indicating melamine exposure can increase oxidative stress. Additionally, we used structure equation modeling to evaluate relative contribution of type of melamine-induced oxidative stress on renal tubular injury and found that MDA mediated 36 %-53 % of the total effect of melamine on a biomarker of renal tubular injury, N-Acetyl-β-d Glucosaminidase (NAG). In conclusion, our findings suggest exposure to low-dose melamine can increase oxidative stress and increase the risk of early damage to kidneys in humans.

Prolonged exposure of mouse and human podocytes to insulin induces insulin resistance through lysosomal and proteasomal degradation of the insulin receptor

AIMS/HYPOTHESIS

Podocytes are insulin-responsive cells of the glomerular filtration barrier and are key in preventing albuminuria, a hallmark feature of diabetic nephropathy. While there is evidence that a loss of insulin signalling to podocytes is detrimental, the molecular mechanisms underpinning the development of podocyte insulin resistance in diabetes remain unclear. Thus, we aimed to further investigate podocyte insulin responses early in the context of diabetic nephropathy.

METHODS

Conditionally immortalised human and mouse podocyte cell lines and glomeruli isolated from db/db DBA/2J mice were studied. Podocyte insulin responses were investigated with western blotting, cellular glucose uptake assays and automated fluorescent imaging of the actin cytoskeleton. Quantitative (q)RT-PCR was employed to investigate changes in mRNA. Human cell lines stably overproducing the insulin receptor (IR) and nephrin were also generated, using lentiviral constructs.

RESULTS

Podocytes exposed to a diabetic environment (high glucose, high insulin and the proinflammatory cytokines TNF-α and IL-6) become insulin resistant with respect to glucose uptake and activation of phosphoinositide 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) signalling. These podocytes lose expression of the IR as a direct consequence of prolonged exposure to high insulin concentrations, which causes an increase in IR protein degradation via a proteasome-dependent and bafilomycin-sensitive pathway. Reintroducing the IR into insulin-resistant human podocytes rescues upstream phosphorylation events, but not glucose uptake. Stable expression of nephrin is also required for the insulin-stimulated glucose uptake response in podocytes and for efficient insulin-stimulated remodelling of the actin cytoskeleton.

CONCLUSIONS/INTERPRETATION

Together, these results suggest that IR degradation, caused by high levels of insulin, drives early podocyte insulin resistance, and that both the IR and nephrin are required for full insulin sensitivity of this cell. This could be highly relevant for the development of nephropathy in individuals with type 2 diabetes, who are commonly hyperinsulinaemic in the early phases of their disease.

Baicalin protects against zearalenone-induced chicks liver and kidney injury by inhibiting expression of oxidative stress, inflammatory cytokines and caspase signaling pathway

Zearalenone (ZEA) is a secondary metabolite produced by fungi such as Fusarium and Fusarium flavum, which is classified as a mycotoxin. Crops and feed in a humid surrounding are widely polluted by ZEA, which further endangering the healthful aquaculture of poultry and even human health. Up to now, prevention and cure of mycotoxicosis is still a crucial subject of poultry husbandry. Baicalin (BAI) is a flavonoid refined from dried roots of Scutellaria baicalensis possessing the function of hepatoprotective, anti-inflammatory, anti-oxidant, and anti-atherosclerotic efficacies.etc. But whether Baicalin also has a protective effect against ZEA intoxication is unclear. Therefore, the aim of this study was to establish a model of ZEA-induced toxic injury in chicks, and then to investigate the way in which Baicalin plays a protective role in the mechanism of ZEA-induced liver and kidney injury in chicks. The results exhibit that Baicalin could not only significantly decrease aspartate aminotransferase (AST) , alanine aminotransferase (ALT) and creatinine (Cre) levels in serum, but also ameliorate ZEA-induced pathologic changes of liver and kidney. Baicalin could also significantly regulate ZEA-induced the changes of catalase (CAT) , malondialdehyde (MDA) , total sulfhydryl group , except for glutathione peroxidase (GSH-px) , and inhibit the mRNA levels of inflammatory cytokines tumor necrosis factor-α (TNF-α) , interleukin-1β (IL-1β) and cyclooxygenase-2 (COX-2) with caspase-3 and caspase-11 in the caspase signaling pathway , meanwhile inhibit the cell apoptosis in immunohistochemistry. In summary, we successfully established a model of ZEA-induced liver injury in chicks, and confirm that Baicalin can reduce ZEA-induced liver and kidney injury in chicks. The mechanism of these effects is via inhibiting inflammation, oxidative stress and apoptosis, which also indicates the potential applicability of Baicalin for the prevention and treatment of ZEA-induced toxicity in chicks.

Gamma-Glutamyl Cysteine Attenuates Tissue Damage and Enhances Tissue Regeneration in a rat Model of Lead-Induced Nephrotoxicity

Lead is a biohazardous metal that is commonly involved in human illness including renal injury. Although it is a non-redox reactive metal, lead-induced renal injury is largely based on oxidative stress. The current work aimed at exploring the possible protective effect of γ-glutamyl cysteine (γGC) against lead-induced renal injury. Rats were allocated to normal and γGC control groups, lead-treated group, and lead and γGC-treated group. γGC alleviated lead-induced renal injury as evidenced by attenuation of histopathological aberration, amelioration of oxidative injury as demonstrated by significant reduction in lipid and protein oxidation, elevation of total antioxidant capacity, and glutathione level. The activity of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) was significantly elevated. γGC significantly decreased levels of the proinflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-1β and the activity of the apoptotic marker caspase-3. In addition, γGC reduced kidney lead content, enhanced weight gain, and improved renal function as demonstrated by reduced serum levels of urea and creatinine. Importantly, γGC upregulated proliferating cell nuclear antigen (PCNA) expression, denoting enhanced renal regenerative capacity. Together, our findings highlight evidence for alleviating effects of γGC against lead-induced renal injury that is potentially mediated through diminution of oxidative tissue injury, reduction of inflammatory response, attenuation of apoptosis, and enhancement of renal regenerative capacity.

Nrf2 deficiency aggravates the kidney injury induced by subacute cadmium exposure in mice

Cadmium (Cd) is a heavy metal pollutant that adversely effects the kidney. Oxidative stress and inflammation are likely major mechanisms of Cd-induced kidney injury. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is crucial in regulating antioxidant and inflammatory responses. To investigate the role of Nrf2 in the development of subacute Cd-induced renal injury, we utilized Nrf2 knockout (Nrf2-KO) and control mice (Nrf2-WT) which were given cadmium chloride (CdCl₂, 1 or 2 mg/kg i.p.) once daily for 7 days. While subacute CdCl₂ exposure induced kidney injury in a dose-dependent manner, after the higher Cd dosage exposure, Nrf2-KO mice showed elevated blood urea nitrogen (BUN) and urinary neutrophil gelatinase-associated lipocalin (NGAL) levels compared to control. In line with the findings, the renal tubule injury caused by 2 mg Cd/kg, but not lower dosage, in Nrf2-KO mice determined by Periodic acid-Schiff staining was more serious than that in control mice. Further mechanistic studies showed that Nrf2-KO mice had more apoptotic cells and severe oxidative stress and inflammation in the renal tubules in response to Cd exposures. Although there were no significant differences in Cd contents of tissues between Cd-exposed Nrf2-WT and Nrf2-KO mice, the mRNA expression of Nrf2 downstream genes, including heme oxygenase 1 and metallothionein 1, were significantly less induced by Cd exposures in the kidney of Nrf2-KO compared with Nrf2-WT mice. In conclusion, Nrf2-deficient mice are more sensitive to kidney injury induced by subacute Cd exposure due to a muted antioxidant response, as well as a likely diminished production of specific Cd detoxification metallothioneins.