Effect of resveratrol on tubular damage and interstitial fibrosis in kidneys of rats exposed to cigarette smoke

Ameliorative effect of montelukast against STZ induced diabetic nephropathy: targeting HMGB1, TLR4, NF-κB, NLRP3 inflammasome, and autophagy pathways

Diabetic nephropathy (DN) is reported as one of the most serious microvascular diabetic complications and the trigger of end-stage renal disease (ESRD), underscoring the concern of any therapeutic intervention directed at ameliorating the development and progression of DN. The current study explored the renoprotective impact of montelukast (Mon) against streptozotocin (STZ)-induced DN in rats compared to a standard anti-hyperglycemic insulin (Ins) treatment. Diabetes was induced by a single dose of STZ (55 mg/kg). Diabetic rats were treated with Mon (10 and 20 mg/kg, oral gavage) for eight weeks. Mon administration for 8 weeks after induction of diabetes conferred significant dose-dependent renoprotection, independent of blood glucose levels (unlike Ins), as evidenced by the improvement in serum creatinine, and blood urea nitrogen (BUN), and ameliorated STZ-induced renal necrotic, inflammatory alterations, and renal fibrosis. Additionally, Mon treatment in diabetic rats significantly restored redox hemostasis as evidenced by malondialdehyde (MDA) and total antioxidant capacity (TAC) levels; significantly reduced the renal expression of high mobility group box (HMGB) 1, toll-like receptor (TLR) 4, nuclear factor kappa B (NF-κB) (in the nucleus), NOD-like receptor family pyrin domain containing (NLRP) 3, and interleukin (IL)-1β. Moreover, Mon administration ameliorated the dysregulation in autophagy as evidenced by p62 and microtubule-associated protein 1A/1B-light chain 3 (LC3)-II levels. In conclusion, the renoprotective effect of Mon is potentially associated with its modulatory effect on inflammatory cytokines, antioxidant properties, and autophagy.

Toll-like receptor 4 promotes the inflammatory response in septic acute kidney injury by promoting p38 mitogen-activated protein kinase phosphorylation

Septic acute kidney injury (AKI) contributes to the mortality and morbidity of sepsis patients. Toll-like Receptor 4 (TLR4) has prominent roles in septic AKI. This study investigated the functions of TLR4 in septic AKI. A septic AKI mouse model was established by cecal ligation and puncture surgery. Mouse kidney function and kidney tissue lesion were examined using corresponding kits and H&E staining. The in vitro cell model of septic AKI was established by lipopolysaccharide induction. Cell viability, inflammatory factor (TNF-α, IL-6, IL-4, IL-1β, IL-18) levels, pyroptotic cell number changes, lactate dehydrogenase (LDH) activity, myeloperoxidase (MOP) concentration, and levels of pyroptosis-associated protein and MyD88, TRIF and p38 MAPK phosphorylation were determined by MTT, ELISA, FAM-FLICA Caspase-1 Detection kit, other corresponding kits, and Western blot. TLR4 was highly expressed in septic AKI mouse kidney tissues and human septic AKI cells. TLR4 knockdown alleviated kidney injury, increased cell viability, and reduced LDH activity and MPO concentration. TLR4 knockdown reduced cell pyroptosis by repressing p38 MAPK phosphorylation through MyD88/TRIF, suppressed pro-inflammatory factor (TNF-α, IL-6, IL-4, IL-1β, IL-18) levels, promoted anti-inflammatory factor (IL-4) level, and reduced inflammatory response, thus playing a protective role in septic AKI. Briefly, TLR4 promoted the inflammatory response in septic AKI by promoting p38 MAPK phosphorylation through MyD88/TRIF.

Sigesbeckia orientalis Extract Ameliorates the Experimental Diabetic Nephropathy by Downregulating the Inflammatory and Oxidative Stress Signaling Pathways

Diabetes in children and its complications are on the rise globally, which is accompanied by increasing in diabetes-related complications. Oxidative stress and inflammation induced by elevated blood sugar in diabetic patients are considered risk factors associated with the development of diabetes complications, including chronic kidney disease and its later development to end-stage renal disease. Microvascular changes within the kidneys of DM patients often lead to chronic kidney disease, which aggravates the illness. Sigesbeckia orientalis extract (SOE), reported to have strong antioxidative and excellent anti-inflammatory activities, is used in the modern practice of traditional Chinese medicine. Kidneys from three groups of control mice (CTR), mice with streptozotocin (STZ)-induced diabetes (DM), and mice with STZ-induced DM treated with SOE (DMRx) were excised for morphological analyses and immunohistochemical assessments. Only mice in the DM group exhibited significantly lower body weight, but higher blood sugar was present. The results revealed more obvious renal injury in the DM group than in the other groups, which appeared as greater glomerular damage and tubular injury, sores, and plenty of connective tissues within the mesangium. Not only did the DM group have a higher level of cytokine, tumor necrosis factor, and the oxidative stress marker, 8-hydroxyguanosine expression, but also factors of the nuclear factor pathway and biomarkers of microvascular status had changed. Disturbances to the kidneys in DMRx mice were attenuated compared to the DM group. We concluded that SOE is an effective medicine, with antioxidative and anti-inflammatory abilities, to protect against or attenuate diabetic nephropathy from inflammatory disturbances by oxidative stress and to cure vessel damage in a hyperglycemic situation.

Dose-dependent renoprotective impact of Lactoferrin against glycerol-induced rhabdomyolysis and acute kidney injury

Acute kidney injury (AKI) is a clinical disorder with a serious impact on the quality of patients' lives. Considering its increased worldwide prevalence, investigating novel therapeutic approaches for the management of AKI has been inevitable. Lactoferrin (LF), a glycoprotein belonging to the transferrin family, is known to play an important role in regulating iron homeostasis. This study aimed to evaluate the renoprotective effect of LF (30, 100, and 300 mg/kg orally) against glycerol (GLY)-induced rhabdomyolysis (RM) in rats. RM was induced by a single intramuscular injection of GLY 50% (10 mL/kg) after 24-h water deprivation in male Sprague-Dawley rats. LF administration conferred significant dose-dependent renoprotective impact against GLY-induced RM as evidenced by the decreased renal/somatic index and the significant improvement in renal functions as confirmed by the significant increase in creatinine clearance, decrease in serum creatinine and blood urea nitrogen, and improvement in albuminuria and proteinuria. Redox homeostasis was significantly restored in a dose-dependent manner as well. Moreover, serum interleukin-1β (IL-1β) was significantly decreased with a parallel significant decrease in renal NOD-like receptor family pyrin domain containing 3 (NLRP3) and thioredoxin interacting protein (TXNIP), kidney injury molecule-1 (KIM-1), caspase-3 expression, nuclear factor kappa B (NF-κB), cluster of differentiation (CD68) expression, and a significant increase in renal nuclear factor erythroid 2-related factor 2 (NRF2) expression. Ultimately, LF administration was associated with a significant amelioration of GLY-induced renal necrotic and inflammatory alterations. In conclusion, the observed dose-dependent nephroprotective effect of LF can be attributed to its modulatory impact on inflammatory/apoptotic/oxidative signaling.

Anti-Tn Monoclonal Antibody Ameliorates Hyperoxia-Induced Kidney Injury by Suppressing Oxidative Stress and Inflammation in Neonatal Mice

The Tn antigen, an N-acetylgalactosamine structure linked to serine or threonine, has been shown to induce high-specificity, high-affinity anti-Tn antibodies in mice. Maternal immunization with the Tn vaccine increases serum anti-Tn antibody titers and attenuates hyperoxia-induced kidney injury in neonatal rats. However, immunizing mothers to treat neonatal kidney disease is clinically impractical. This study is aimed at determining whether anti-Tn monoclonal antibody treatment ameliorates hyperoxia-induced kidney injury in neonatal mice. Newborn BALB/c mice were exposed to room air (RA) or normobaric hyperoxia (85% O₂) for 1 week. On postnatal days 2, 4, and 6, the mice were injected intraperitoneally with PBS alone or with anti-Tn monoclonal antibodies at 25 μg/g body weight in 50 μL phosphate-buffered saline (PBS). The mice were divided into four study groups: RA + PBS, RA + anti-Tn monoclonal antibody, O₂ + PBS, and O₂ + anti-Tn monoclonal antibody. The kidneys were excised for histology, oxidative stress, cytokine, and Western blot analyses on postnatal day 7. The O₂ + PBS mice exhibited significantly higher kidney injury scores, 8-hydroxy-2'-deoxyguanosine (8-OHdG) and nuclear factor-κB (NF-κB) expression, and cytokine levels than did the RA + PBS mice or RA + anti-Tn mice. Anti-Tn monoclonal antibody treatment reduced kidney injury and cytokine levels to normoxic levels. The attenuation of kidney injury was accompanied by a reduction of oxidative stress and NF-κB expression. Therefore, we propose that anti-Tn monoclonal antibody treatment ameliorates hyperoxia-induced kidney injury by suppressing oxidative stress and inflammation in neonatal mice.

Valproate attenuates hypertonic glycerol-induced rhabdomyolysis and acute kidney injury

BACKGROUND AND AIM

The current study investigated the effects of treatment with 300 mg/kg valproic acid on rhabdomyolysis and acute kidney injury induced by intramuscular injection of hypertonic glycerol in rats.

METHODS

Four groups of male wistar rats: control and hypertonic glycerol, valproic acid and valproic acid + hypertonic glycerol treated groups were used. Blood urea nitrogen, serum creatinine, creatinine kinase (CK) and CK MB, myoglobin and renal reduced glutathione (GSH) levels were measured. Histopathological examination of the kidneys was carried out to evaluate the degree of renal injury in each group. The expression of interleukin-1 beta "IL-1β" in renal tissue was detected using immunohistochemistry.

RESULTS

Hypertonic glycerol administration led to severe renal tubular damage with a significant elevation of blood urea nitrogen, serum creatinine, creatinine kinase, CK MB and myoglobin levels and overexpression of IL-1β compared to control group. Valproic acid administration attenuated both the muscle injury and the acute kidney injury induced by hypertonic glycerol, estimated through a significant reduction of creatinine kinase, myoglobin, and serum creatinine. Valproic acid administration caused a significant increase in GSH in the hypertonic glycerol + valproic acid group compared to the hypertonic glycerol group. A significant decrease in tubular necrosis grade, and expression of IL-1β in hypertonic glycerol + valproic acid group compared to the hypertonic glycerol group was observed.

CONCLUSION

This study demonstrates, for the first time to the best of our knowledge, that valproic acid could ameliorate the rhabdomyolysis and the related acute kidney injury in rats.

Immunization with anti-Tn immunogen in maternal rats protects against hyperoxia-induced kidney injury in newborn offspring

BACKGROUND

Neonatal hyperoxia increases oxidative stress and adversely disturbs glomerular and tubular maturity. Maternal Tn immunization induces anti-Tn antibody titer and attenuates hyperoxia-induced lung injury in neonatal rats.

METHODS

We intraperitoneally immunized female Sprague-Dawley rats (6 weeks old) with Tn immunogen (50 μg/dose) or carrier protein five times at biweekly intervals on 8, 6, 4, 2, and 0 weeks before the delivery day. The pups were reared for 2 weeks in either room air (RA) or in 85% oxygen-enriched atmosphere (O₂), thus generating four study groups, namely carrier protein + RA, Tn vaccine + RA, carrier protein + O₂, and Tn vaccine + O₂. On postnatal day 14, the kidneys were harvested for the oxidative stress marker 8-hydroxy-2'-deoxyguanosine (8-OHdG), nuclear factor-κB (NF-κB), and collagen expression and histological analyses.

RESULTS

Hyperoxia reduced body weight, induced tubular and glomerular injuries, and increased 8-OHdG and NF-κB expression and collagen deposition in the kidneys. By contrast, maternal Tn immunization reduced kidney injury and collagen deposition in neonatal rats. Furthermore, kidney injury attenuation was accompanied by a reduction in 8-OHdG and NF-κB expression.

CONCLUSION

Maternal Tn immunization protects against hyperoxia-induced kidney injury in neonatal rats by attenuating oxidative stress and NF-κB activity.

IMPACT

Hyperoxia increased nuclear factor-κB (NF-κB) activity and collagen deposition in neonatal rat kidney. Maternal Tn immunization reduced kidney injury as well as collagen deposition in neonatal rats. Maternal Tn immunization reduced kidney injury and was associated with a reduction in 8-hydroxy-2'-deoxyguanosine and NF-κB activity. Tn vaccine can be a promising treatment modality against hyperoxia-induced kidney injury in neonates.

Intravenous Arginine Administration Downregulates NLRP3 Inflammasome Activity and Attenuates Acute Kidney Injury in Mice with Polymicrobial Sepsis

Acute kidney injury (AKI) is a major complication of sepsis. Nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasomes are multiprotein complexes that mediate septic AKI. L-arginine (Arg) is a conditionally essential amino acid in catabolic conditions and a substrate for nitric oxide (NO) production; however, its use in sepsis is controversial. This study investigated the effect of intravenous Arg supplementation on modulating NLRP3 inflammasome activity in relation to septic AKI. Mice were divided into normal control (NC), sham, sepsis saline (SS), and sepsis Arg (SA) groups. In order to investigate the role of NO, L-N6-(1-iminoethyl)-lysine hydrochloride (L-NIL), an inducible NO synthase inhibitor, was administered to the sepsis groups. Sepsis was induced using cecal ligation and puncture (CLP). The SS and SA groups received saline or Arg via tail vein 1 h after CLP. Mice were sacrificed at 6, 12, and 24 h after sepsis. The results showed that compared to the NC group, septic mice had higher plasma kidney function parameters and lower Arg levels. Also, renal NLRP3 inflammasome protein expression and tubular injury score increased. After Arg treatment, plasma Arg and NO levels increased, kidney function improved, and expressions of renal NLRP3 inflammasome-related proteins were downregulated. Changes in plasma NO and renal NLRP3 inflammasome-related protein expression were abrogated when L-NIL was given to the Arg sepsis groups. Arg plus L-NIL administration also attenuated kidney injury after CLP. The findings suggest that intravenous Arg supplementation immediately after sepsis restores plasma Arg levels and is beneficial for attenuating septic AKI, partly via NO-mediated NLRP3 inflammasome inhibition.

Cathelicidin attenuates hyperoxia-induced kidney injury in newborn rats

Aim: Supplemental oxygen is often used to treat neonates with respiratory disorders. Human and animal studies have demonstrated that neonatal hyperoxia increases oxidative stress and induces damage and collagen deposition in kidney during the perinatal period. Cathelicidin LL-37 is one important group of human antimicrobial peptides which exhibits antioxidant activity and its overexpression resists hyperoxia-induced oxidative stress. This study was designed to evaluate the protective effects of cathelicidin in hyperoxia-induced kidney injury in newborn rats.

Methods: Sprague-Dawley rat pups were reared in either room air (RA) or hyperoxia (85% O₂) and were randomly treated with low-dose (4 mg/kg) and high-dose (8 mg/kg) cathelicidin in normal saline (NS) administered intraperitoneally on postnatal days 1–6. The following six groups were obtained: RA + NS, RA + low-dose cathelicidin, RA + high-dose cathelicidin, O₂ + NS, O₂ + low-dose cathelicidin, and O₂ + high-dose cathelicidin. Kidneys were taken for Western blot and histological analyses on postnatal day 7.

Results: The hyperoxia-reared rats exhibited significantly lower body weights and anti-inflammatory M2 macrophages, but the kidney injury scores, oxidative stress marker 8-hydroxy-2'-deoxyguanosine (8-OHdG)-positive cells, pro-inflammatory M1 macrophages, collagen deposition, and NF-κB expression were higher than did the RA-reared rats.

Conclusions: Cathelicidin treatment attenuated kidney injury as evidenced by lower kidney injury scores, 8-OHdG-positive cells, collagen deposition, and reversion of hyperoxia-induced M1/M2 macrophage polarization. The role of Cathelicidin in ameliorates kidney injury of the hyperoxia newborn rats was accompanied by decreased NF-κB expression, which probably through the modulating NF-κB activity in the kidney.

Anti-secretogranin III therapy of oxygen-induced retinopathy with optimal safety

Retinopathy of prematurity (ROP) with pathological retinal neovascularization is the most common cause of blindness in children. ROP is currently treated with laser therapy or cryotherapy, both of which may adversely affect the peripheral vision with limited efficacy. Owing to the susceptibility of the developing retina and vasculatures to pharmacological intervention, there is currently no approved drug therapy for ROP in preterm infants. Secretogranin III (Scg3) was recently discovered as a highly disease-restricted angiogenic factor, and a Scg3-neutralizing monoclonal antibody (mAb) was reported with high efficacy to alleviate oxygen-induced retinopathy (OIR) in mice, a surrogate model of ROP. Herein we independently investigated the efficacy of anti-Scg3 mAb in OIR mice and characterized its safety in neonatal mice. We developed a new Scg3-neutralizing mAb recognizing a distinct epitope and independently established the therapeutic activity of anti-Scg3 therapy to alleviate OIR-induced pathological retinal neovascularization in mice. Importantly, anti-Scg3 mAb showed no detectable adverse effects on electroretinography and developing retinal vasculature. Furthermore, systemic anti-Scg3 mAb induced no renal tubular injury or abnormality in kidney vessel development and body weight gain of neonatal mice. In contrast, anti-vascular endothelial growth factor drug aflibercept showed significant side effects in neonatal mice. These results suggest that anti-Scg3 mAb may have the safety and efficacy profiles required for ROP therapy.

Diclofenac induced gastrointestinal and renal toxicity is alleviated by thymoquinone treatment

The aim of this study was to investigate whether thymoquinone (TQ) could alleviate diclofenac (DCLF)-induced gastrointestinal and renal toxicity in rats. Diclofenac was administered via intramuscular injection twice daily for 5 days and TQ was given by gavage for the same period. Hematological and biochemical profiles were measured with autoanalyzers while reactive oxygen/nitrogen species (ROS/RNS) generation and total antioxidant capacity (TAC) were assayed by standard kits. Tissue injuries were evaluated by microscopy and histopathological scoring. Diclofenac treatment caused kidney and liver function test abnormalities, reduced hematocrit and hemoglobin levels but increased WBC and platelet counts. Histopathological findings showed renal tubular damage, gastrointestinal lesions and increased fibrosis in DCLF treated rats. Thymoquinone administration, along with DCLF treatment, attenuated hematological test abnormalities and DCLF induced renal functional impairment as evident by significantly restored serum creatinine and blood urea nitrogen levels. Similarly, TQ treatment significantly alleviated liver function test abnormalities and decreased tissue injury in the stomach and duodenum. Diclofenac treatment caused increased ROS/RNS formation and decreased TAC in the kidney, stomach and duodenal tissue. Thymoquinone administration increased gastrointestinal and renal TAC in DCLF treated rats. These results indicate that TQ could ameliorate gastrointestinal and renal toxicity induced by high dose DCLF treatment.

Hyperglycemia activates the renin-angiotensin system and induces epithelial-mesenchymal transition in streptozotocin-induced diabetic kidneys

INTRODUCTION

The renin-angiotensin system and epithelial-mesenchymal transition play crucial roles in the development of kidney fibrosis. The connection between the renin-angiotensin system and transforming growth factor-β in epithelial-mesenchymal transition remains largely unknown.

MATERIALS AND METHODS

We assessed oxidative stress, cytokine levels, renal morphology, profibrotic growth factor and renin-angiotensin system component expression, and cell-specific E- and N-cadherin expression in the kidneys of gerbils with streptozotocin-induced diabetes mellitus.

RESULTS

Animals in the experimental group received an intraperitoneal injection of streptozotocin to induce diabetes. The diabetic gerbil kidneys presented kidney injury, which was manifested as distorted glomeruli, necrosis of tubular cells, dilated tubular lumen, and brush border loss. Additionally, the diabetic gerbil kidneys exhibited significantly higher expressions of 8-hydroxy-2'-deoxyguanosine, nuclear factor-kB, toll-like receptor 4, tumor necrosis factor-α, transforming growth factor-β, connective tissue growth factor, α-smooth muscle actin, and N-cadherin and higher collagen deposition than did the control gerbil kidneys. Compared with the control kidneys, the diabetic gerbil kidneys exhibited significantly lower E-cadherin expression. These epithelial-mesenchymal transition characteristics were associated with an increase in renin-angiotensin system expression in the diabetic gerbils.

CONCLUSIONS

We demonstrate that hyperglycemia activated the renin-angiotensin system, induced epithelial-mesenchymal transition, and contributed to kidney fibrosis in an experimental diabetes mellitus model.

Glutamine Administration in Early or Late Septic Phase Downregulates Lymphocyte PD-1/PD-L1 Expression and the Inflammatory Response in Mice With Polymicrobial Sepsis

BACKGROUND

Sepsis is a severe inflammatory response to infection. Excessive compensation to inflammation leads to dysregulated immune response that ultimately results in organ damage and lethality of sepsis. This study administered glutamine (GLN) in the early or late phase of sepsis to investigate its effects on regulating leukocyte programmed cell death 1 (PD-1) and its ligand (programmed cell death ligand 1 [PD-L1]) expression, macrophage function, inflammation, and acute kidney injury in sepsis.

METHODS

Mice were randomly assigned to cecal ligation and puncture (CLP) or sham-operated groups. Septic mice were respectively injected once with saline or 0.75 g GLN/kg body weight at 3 or 10 hours post-CLP via tail vein. All mice were sacrificed 24 hours after CLP.

RESULTS

Sepsis enhanced the percentage of interferon-γ-expressing and interleukin (IL)-17A-expressing CD4⁺ T cells, expression of PD-1 on T cells, and PD-L1 on B cells and monocytes. Inflammatory mediator messenger RNA (mRNA) expression in kidney tissues and proapoptotic caspase-3 mRNA expression in mesenteric lymph nodes were also upregulated. GLN administration decreased plasma IL-6 level, downregulated the percentage of IL-17A-expressing CD4⁺ T cells, attenuated macrophage dysfunction, decreased caspase-3 mRNA expression, and reduced PD-1/PD-L1 expression by T and B cells. Histological findings also showed that kidney damage was attenuated. GLN administered at 3 and 10 hours after CLP offered nearly equal effects on PD-1/PD-L1 and inflammatory mediator expression after CLP.

CONCLUSIONS

These findings suggest that a single dose of GLN administration in either the early or late phase during sepsis promotes a more balanced immune regulation and reduced systemic and kidney inflammatory responses in mice.

Acute Exposure to Cigarette Smoking Followed by Myocardial Infarction Aggravates Renal Damage in an In Vivo Mouse Model

Cigarette smoking (S) is a risk factor for progressive chronic kidney disease, renal dysfunction, and renal failure. In this study, the effect of smoking on kidney function was investigated in a mouse model of myocardial infarction (MI) using 4 groups: control (C), smoking (S), MI, and S+MI. Histological analysis of S+MI group showed alterations in kidney structure including swelling of the proximal convoluted tubules (PCTs), thinning of the epithelial lining, focal loss of the brush border of PCTs, and patchy glomerular retraction. Molecular analysis revealed that nephrin expression was significantly reduced in the S+MI group, whereas sodium-hydrogen exchanger-1 (NHE-1) was significantly increased, suggesting altered glomerular filtration and kidney functions. Moreover, S+MI group, but not S alone, showed a significant increase in the expression of connective tissue growth factor (CTGF) and fibrotic proteins fibronectin (FN) and α-smooth muscle actin (SMA), in comparison to controls, in addition to a significant increase in mRNA levels of IL-6 and TNF-α inflammatory markers. Finally, reactive oxygen species (ROS) production was significantly accentuated in S+MI group concomitant with a significant increase in NOX-4 protein levels. In conclusion, smoking aggravates murine acute renal damage caused by MI at the structural and molecular levels by exacerbating renal dysfunction.

Long-term administration of advanced glycation end-product stimulates the activation of NLRP3 inflammasome and sparking the development of renal injury

The accumulation of advanced glycation end-products (AGEs) and the enhanced interaction of AGE with their cellular receptor (RAGE) have been implicated in the progression of chronic kidney disease. The purpose of this study was to examine whether the AGE/RAGE-induced nephrotoxic effects are associated with inflammasome activation and endothelial dysfunction. Chronic renal injury was examined in BALB/c mice by the long-term administration of carbonyl-AGE for 16 weeks. Endothelial dysfunction was detected by measuring the number of circulating endothelial progenitor cells (EPCs) and the levels of nitric oxide synthase (eNOS) and nitric oxide (NO) in kidneys. Results showed that administration of methylglyoxal-bovine serum albumin (MG-BSA) AGE accelerated renal MG, carboxyethyl lysine, carboxymethyl lysine and malondialdehyde formation and, in parallel, the levels of serum creatinine and blood urea nitrogen (BUN) were significantly increased. Expression of RAGE and NLRP3 inflammasome-related proteins (TXNIP, NLRP3, procaspase-1 and caspase-1) and IL (interleukin)-1β secretion were upregulated, whereas the levels of EPCs, eNOS and NO were lower in MG-BSA-treated mice. This induction by MG-BSA was significantly inhibited by RAGE antagonist. Our results firstly reveal a possible mechanism of AGE-mediated renal dysfunction upon NLRP3 inflammasome activation. Therapeutic blockade of RAGE may ameliorate renal and endothelial functions in subjects under high AGE burden.

Fish Oil-Based Fat Emulsion Reduces Acute Kidney Injury and Inflammatory Response in Antibiotic-Treated Polymicrobial Septic Mice

Acute kidney injury (AKI) is a common complication in sepsis. This study compared the effects of a fish oil-based with a mixed oil fat emulsion on remote renal injury in an antibiotic-treated septic murine model. Mice were randomly assigned to a normal control (NC) group and three septic groups. Sepsis was induced by cecal ligation and puncture (CLP). The antibiotic was injected intraperitoneally (IP) after CLP and then daily till the time of sacrifice. Three hours after antibiotic treatment, one of the septic groups was injected IP with a fish oil-based emulsion (FO), while the other two groups were given either a mixed oil emulsion (MO) or saline (SC). The septic groups were further divided into two separate time groups, with blood and kidneys samples collected at 24 h or 72 h post-CLP. The results showed that sepsis leads to the activation of neutrophils, T helper (Th)1/Th-2/Th-17 and Treg cells (p < 0.05). Plasma NGAL and mRNA expressions of renal MyD88 and TLR4 were also enhanced (p < 0.05). Compared to the SC group, the group given the fish oil-based emulsion had decreased plasma NGAL by 22% and Treg by 33%. Furthermore, renal gene expressions of MyD88 and TLR4 reduced by 46% and 62%, respectively, whereas heat shock protein 70 and peroxisome proliferator-activated receptor-γ increased by 158% and 69%, respectively (p < 0.05), at Day 3 after CLP. These results suggest that administration of a fish oil-based emulsion has favorable effects, maintaining blood T cell percentage, downregulating Treg expression, attenuating systemic and local inflammation and offering renal protection under conditions of antibiotic-treated polymicrobial sepsis.

Modulatory Effects of Astragalus Polysaccharides on T-Cell Polarization in Mice with Polymicrobial Sepsis

BACKGROUND

This study evaluated the impact of different doses of Astragalus polysaccharides (APS) on the functional status and phenotype of T cells during polymicrobial sepsis.

METHODS

On day 1 after cecal ligation and puncture, mice were treated with either saline, 100 (A100), 200 (A200), or 400 mg APS/kg body weight (BW) (A400) by an intraperitoneal injection daily for 4 days. All mice were sacrificed 5 days after the operation.

RESULTS

APS treatment reversed the sepsis-induced decrement in the T helper (Th) cell population, and the percentage of activated Th cells also increased in the spleen and Peyer's patches. APS administration downregulated the percentages of circulating Th2 cells and regulatory T cells (Treg), and the percentage of Th17 cells in blood was upregulated in the A400 group. Weight loss and kidney injury were attenuated in the A100 and A200 groups but not in the A400 group at the end of the study.

CONCLUSIONS

Treatments with 100 and 200 mg APS/kg BW reduced Treg populations and elicited a more-balanced Th1/Th2 response that consequently attenuated immunosuppression in polymicrobial sepsis. High-dose APS administration led to excessive responses of Th17 cells which may have adverse effects in sepsis-induced organ injury.

Neonatal Hyperoxia Exposure Induces Kidney Fibrosis in Rats

BACKGROUND

Human and animal studies have demonstrated that neonatal hyperoxia increases oxidative stress and adversely affects glomerular and tubular maturity. This study was undertaken to determine how exposure to neonatal hyperoxia affected kidney morphology and fibrosis and to elucidate the relationship between connective tissue growth factor (CTGF) and collagen expression in rat kidneys.

METHODS

Sprague-Dawley rat pups were exposed to either hyperoxia or ambient air. The control groups were maintained in ambient air for 1 week and 3 weeks. The hyperoxia groups were exposed to >95% O2 for 1 week and subsequently placed in an environment of 60% O2 for an additional 2 weeks. The animals were euthanized on Postnatal Day 7 or 21 and the kidneys underwent histological analyses and oxidative stress and total collagen measurements.

RESULTS

The rats reared in O2-enriched air exhibited significantly higher tubular injury scores (1.4 ± 0.5 vs. 0.7 ± 0.7 on Day 7; 1.4 ± 0.5 vs. 0.6 ± 0.5 on Day 21), a larger proportion of the cortex occupied by glomeruli (25.5 ± 4.1 vs. 21.3 ± 3.1% on Day 7; 20.1 ± 3.5 vs. 17.1 ± 1.7% on Day 21), larger glomerular sizes (84.7 ± 5.8 vs. 77.5 ± 6.1 μm on Day 7; 88.4 ± 2.9 vs. 84.9 ± 3.1 μm on Day 21), and higher total collagen content (54.1 ± 27.5 vs. 18.3 ± 6.3 μg/mg protein on Day 7; 397.4 ± 32.8 vs. 289.5 ± 80.0 μg/mg protein on Day 21) than did rats reared in ambient air. Immunohistochemical expressions of oxidative stress marker 8-hydroxy-2'-deoxyguanosine and CTGF immunoreactivities were significantly higher in the rats reared in O2-enriched air compared with the rats reared in ambient air on Postnatal Days 7 and 21.

CONCLUSION

Neonatal hyperoxia exposure contributes to kidney fibrosis, which is probably caused by activated CTGF expression.

Maternal nicotine exposure during gestation and lactation induces kidney injury and fibrosis in rat offspring

BACKGROUND

Maternal tobacco smoke exposure adversely affected fetal kidney development. Nicotine stimulates epithelial-mesenchymal transition and connective tissue growth factor (CTGF) expression in the renal epithelium. We hypothesized that maternal nicotine exposure would induce kidney fibrosis and involve CTGF in newborn rats.

METHODS

Nicotine was administered to pregnant Sprague-Dawley rats at a dose of 6 mg/kg/d from gestational days 7-21 and gestational day 7 to postnatal day 14. A control group was injected with normal saline. Neonatal kidney tissues underwent histological analysis, collagen measurement, and western blot analysis.

RESULTS

Tubular injury scores and total collagen contents were significantly higher in rats born to nicotine-treated dams than in rats born to normal saline-treated dams on postnatal days 7 and 21. Masson's trichrome staining further verified the presence of kidney fibrosis. Prenatal and/or postnatal nicotine exposure increased CTGF expression on postnatal days 7 and 21.

CONCLUSION

Maternal nicotine exposure during gestation and lactation induces neonatal kidney fibrosis, and CTGF may be involved in the pathogenesis of kidney fibrosis. These results may be relevant to premature low-birth-weight infants who are conveyed a high risk of developing chronic kidney disease and exposed to breast milk of smoking mothers during the neonatal period.

Prenatal nicotine exposure induced GDNF/c-Ret pathway repression-related fetal renal dysplasia and adult glomerulosclerosis in male offspring

Prenatal nicotine exposure could induce fetal renal dysplasia associated with the suppression of the GDNF/c-Ret pathway and adult glomerulosclerosis in male offspring, which might be mediated by alterations in angiotensin II receptors.

Resveratrol increases nitric oxide production in the rat thick ascending limb via Ca2+/calmodulin

The thick ascending limb of the loop of Henle reabsorbs 30% of the NaCl filtered through the glomerulus. Nitric oxide (NO) produced by NO synthase 3 (NOS3) inhibits NaCl absorption by this segment. Resveratrol, a polyphenol, has beneficial cardiovascular and renal effects, many of which are mediated by NO. Resveratrol increases intracellular Ca²⁺ (Ca_i) and AMP kinase (AMPK) and NAD-dependent deacetylase sirtuin1 (SIRT1) activities, all of which could activate NO production. We hypothesized that resveratrol stimulates NO production by thick ascending limbs via a Ca²⁺/calmodulin-dependent mechanism. To test this, the effect of resveratrol on NO bioavailability was measured in thick ascending limb suspensions. Ca_i was measured in single perfused thick ascending limbs. SIRT1 activity and expression were measured in thick ascending limb lysates. Resveratrol (100 µM) increased NO bioavailability in thick ascending limb suspensions by 1.3±0.2 AFU/mg/min (p<0.03). The NOS inhibitor L-NAME blunted resveratrol-stimulated NO bioavailability by 96±11% (p<0.03). The superoxide scavenger tempol had no effect. Resveratrol elevated Ca_i from 48±7 to 135±24 nM (p<0.01) in single tubules. In Ca²⁺-free media, the resveratrol-induced increase in NO was blunted by 60±20% (p<0.05) and the rise in Ca_i reduced by 80%. Calmodulin inhibition prevented the resveratrol-induced increase in NO (p<0.002). AMPK inhibition had no effect. Resveratrol did not increase SIRT1 activity. We conclude that resveratrol increases NO production in thick ascending limbs via a Ca²⁺/calmodulin dependent mechanism, and SIRT1 and AMPK do not participate. Resveratrol-stimulated NO production in thick ascending limbs may account for part of its beneficial effects.

Resveratrol inhibits collagen I synthesis by suppressing IGF-1R activation in intestinal fibroblasts

AIM: To investigate whether resveratrol (3,4,5-trihydroxy-trans-stilbene) inhibits collagen I synthesis induced by insulin growth factor-1 (IGF-1) in intestinal fibroblasts, and to explore the possible molecular mechanisms.

METHODS: Male Sprague-Dawley rats were randomly divided into two groups: a control group and a 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis group. After 21 d of TNBS administration, the degree of inflammation and fibrosis in colon was measured by HE staining and Masson’s trichrome staining. Western blotting was used to examine collagen I, IGF-1 and silent information regulator 1 (SIRT1) protein expression in colitis tissues. Western blotting and quantitative real-time polymerase chain reaction were used to characterize collagen I protein and col1a2 mRNA expression in mouse intestinal fibroblasts and CCD-¹⁸Co cells treated with IGF-1. A MEK inhibitor (U0126) was used to determine whether IGF-1-induced collagen I expression was mediated by extracellular signal-regulated kinase 1/2 (ERK1/2)-dependent mechanism. Effects of resveratrol on collagen I protein level, insulin growth factor-1 receptor (IGF-1R) and ERK1/2 phosphorylation levels were also examined after IGF-1 treatment in fibroblasts. To evaluate whether SIRT1 was necessary for the anti-fibrosis effect of resveratrol, cells were transfected with SIRT1-specific small interfering RNAs, wild-type SIRT1, and deacetylase-inactive mutant SIRT1.

RESULTS: Collagen I and IGF-1 expression was increased, and SIRT1 expression was decreased (0.67 ± 0.04 vs 1.05 ± 0.07, P < 0.001) in TNBS-induced colitis compared with the control group. In vitro, IGF-1 could induce collagen I expression, mainly through the ERK 1/2 signal pathway. Resveratrol reduced basal and IGF-1-induced collagen I gene and protein expression in intestinal fibroblasts. Overexpression of wild-type SIRT1, not deacetylase-inactive mutant SIRT1, decreased expression of collagen I induced by IGF-1. Moreover, silencing SIRT1 restored collagen I expression in fibroblasts challenged with resveratrol. However, disruption of SIRT1 did not influence the anti-fibrotic effects of resveratrol and IGF-1-induced collagen I expression. Further analysis revealed that resveratrol significantly decreased phosphorylation of IGF-1R and its downstream signaling molecules by inhibiting IGF-1 binding to its receptor.

CONCLUSION: Our data suggest that resveratrol effectively inhibits collagen I synthesis in IGF-1-stimulated fibroblasts, partly by inhibiting IGF-1R activation, and SIRT1 is also responsible for the process.

The effects of resveratrol against trifluralin toxicity in the urinary tract of rats

The herbicide itself and the degradation products are highly toxic on biological systems. The aim of this study is to investigate the potential toxic effects of trifluralin (TRF) on the urinary system of male rats and to investigate the protective effects of resveratrol (RSV) in TRF-induced urinary system damage. A total of 35 male Wistar rats were randomly divided into: (1) control group, (2) sham group, (3) low dose TRF group (0.8 g/kg/day), (4) high dose TRF group (2 g/kg/day) and (5) high dose TRF + RSV group 10 mg/kg/day. RSV was administered for 21 days by intragastric gavage at a dose of 10 mg/kg/day after induction of TRF. Kidney, ureter and urinary bladder tissue was examined using light microscopy and ultrastructurally. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling was performed to detect apoptosis. Superoxide dismutase (SOD), glutathion peroxidase (GPx) and malondialdehyde (MDA) levels were also evaluated biochemically for oxidative stress parameters. Histological evaluation showed that TRF increases apoptosis and oxidative stress, causes histological tissue damages and biochemical changes in the kidneys but does not cause any damage to the ureter and bladder. Treatment with RSV significantly attenuated tissue damage in the urinary system of rats. Apopitotic cells were significantly decreased in the treatment group. Additionally, treatment with RSV decreased SOD and GPx levels and increased MDA levels in the kidney tissue of animals subjected to TRF. These results show that RSV can significantly minimize histological damage and biochemical differences in treating TRF-induced kidney injury in rats.

A novel U-STAT3-dependent mechanism mediates the deleterious effects of chronic nicotine exposure on renal injury

Previous data from our group have demonstrated (Arany I, Grifoni S, Clark JS, Csongradi, Maric C, Juncos LA. Am J Physiol Renal Physiol 301: F125-F133, 2011) that chronic nicotine (NIC) exposure exacerbates acute renal ischemic injury (AKI) in mice that could increase the risk for development and progression of chronic kidney disease (CKD). It has been shown that proximal tubules of the kidney can acquire characteristics that may compromise structural recovery and favor development of inflammation and fibrosis following injury. Chronic NIC exposure can amplify this epithelial process although the mechanism is not identified. Recently, the unphosphorylated form of signal transducer and activator of transcription-3 (U-STAT3) has emerged as a noncanonical mediator of inflammation and fibrosis that may be responsible for the effects of chronic NIC. We found that levels of transforming growth factor β-1 (TGF-β1), α-smooth muscle actin (α-SMA), fibronectin, monocyte chemotactic protein-1 (MCP-1), and expression of U-STAT3 were increased in the ischemic kidneys of NIC-exposed mice. Chronic NIC exposure also increased TGF-β1-dependent F-actin reorganization, vimentin, fibronectin, and α-SMA expression as well as promoter activity of α-SMA and MCP-1 without significant loss of epithelial characteristics (E-cadherin) in cultured renal proximal tubule cells. Importantly, transduction of cells with a U-STAT3 mimetic (Y705F-STAT3) augmented stress fiber formation and also amplified NIC+TGF-β1-induced expression of α-SMA, vimentin, fibronectin, as well as promoter activity of α-SMA and MCP-1. Our results reveal a novel, chronic NIC-exposure-related and U-STAT3-dependent mechanism as mediator of a sustained transcription of genes that are linked to remodeling and inflammation in the kidney during injury. This process may facilitate progression of AKI to CKD. The obtained data may lead to devising therapeutic methods to specifically enhance the protective and/or inhibit adverse effects of STAT3 in the kidney.

Cytoarchitectural alterations in kidney of Wistar rat after oral exposure to cadmium chloride

Male Wistar rats were randomly divided into three groups--A, B and C. A dose of 5 mg and 10 mg of cadmium chloride/kg body weight/day was orally administered to groups B and C, respectively. Rats from group A served as control. Rats were sacrificed on 1st, 2nd, 4th, 6th, and 8th week after initiation of the experiment. Kidneys were removed immediately, fixed in Bouin's fixative, routinely processed and stained with hematoxylin and eosin. The present study showed that the histopathological changes were caused in kidney of rats by cadmium exposure. The changes noticed were mainly--the glomerular swelling (at initial stage), the shrinkage of glomerulus (at later stage), the tubular dilatation, hypertrophy of tubular epithelium, degeneration of glomerulus and renal tubules and deposition of eosin-positive substances in the glomerulus and renal tubules. However, lesions were depended upon the doses and duration of the treatment.

Protective effects of pentoxifylline on cigarette smoking-induced renal tissue damage in rats

In this study, we investigated the protective effect of pentoxifilline (PTX) on smoking-induced damage in rat kidney tissues. Twenty-seven male Wistar rats were used in the study. Animals were divided into three equal groups as follows: Group 1: control group with only normal saline (NS; 0.9% NaCl) injection for 8 weeks; Group 2: cigarette smoking and NS injection for 8 weeks; and Group 3: cigarette smoking and PTX injection for 8 weeks. The rats were sacrificed after 8 weeks and their kidneys were excised for histopathological analysis. Serial paraffin sections (5 µm) of the kidneys were cut and stained with hematoxylin and eosin (H&E) and periodic acid-Schiff (PAS). The terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) method was used to assess apoptosis. Glomerular diameters, glomerular cell number and proximal tubule cell numbers were compared between the groups. Our results showed that PTX treatment prevented negative effects of smoking in rat kidneys. There was a statistically significant difference in all assessed parameters between Group 2 and other groups (p < 0.05). In conclusion, our study shows that PTX treatment is effective in preventing the negative effects of cigarette smoking on kidneys by inhibiting cell damage with its antioxidant properties.