Renal Tumor Necrosis Factor-alpha Research Articles

Empagliflozin protective effects against cisplatin-induced acute nephrotoxicity by interfering with oxidative stress and inflammation in Wistar rats.

Cisplatin (Cis) is a platinum-based antineoplastic drug used in various types of cancers. This drug can induce nephrotoxicity as a cause of acute kidney injury (AKI) by inducing oxidative stress and inflammation. Empagliflozin (Empa) is a newly developed inhibitor of sodium-glucose cotransporter-2 (SGLT2) approved as an antidiabetic medication for patients with type 2 diabetes mellitus. In addition to its blood glucose-lowering effect, Empa has been shown to exert anti-inflammatory and anti-oxidant properties. The current study aimed to investigate the protective effects of Empa on Cis-induced nephrotoxicity in rats. Male Wistar albino rats were divided into five groups, each of six rats: Sham group (received vehicle for 7 days), Control group (received vehicle for 7 days and Cis injection on day 2), Cis + Empa10 (received 10mg/kg Empa for 7 days and Cis injection on day 2), Cis + Empa30 (received 30mg/kg Empa for 7 days and Cis injection on day 2) and, Empa 30 (received 30mg/kg Empa for 7 days). One day after the last injection in each group, rats were weighed and then sacrificed to analyze the hematological, biochemical, and histological parameters. Cis markedly increased levels of inflammatory parameters such as renal tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, and myeloperoxidase (MPO) activity. Notably, malondialdehyde (MDA), blood urea nitrogen (BUN), and creatinine levels were enhanced after Cis administration. Also, the chemotherapeutic agent significantly reduced antioxidant indicators such as renal catalase (CAT), glutathione peroxidase (GpX), and superoxide dismutase (SOD). Furthermore, histopathological examinations also revealed severe renal damage following Cis treatment which was improved by Empa administration. Empa treatment at both doses (10 mg/kg and 30 mg/kg) reversed Cis-induced changes in all the above renal parameters. In conclusion, Empa has protective effects on Cis-induced nephrotoxicity by inhibition of oxidative stress and inflammation.

MicroRNA‐195 regulates blood pressure by inhibiting NKCC2A

We previously showed that inhibition of renal tumor necrosis factor‐alpha (TNF) production induced by high salt intake increases Na+‐K+‐2Cl−cotransporter isoform A (NKCC2A) mRNA, protein, and phospho (p)NKCC2 expression. MicroRNA (miRNA) contributes to blood pressure regulation, however no studies have addressed the regulation of NKCC2 by miRNA. miR‐195 is one of the most abundant miRNAs expressed in the kidney and qRT‐PCR experiments showed that injection of TNF (5ng/g bw) directly into the kidney of male mice up‐regulates miR‐195 in the renal outer medulla (OM) by approximately 3.5‐fold (p<0.05). Subsequently, a potential miR‐195 binding site in the 3′‐UTR of NKCC2A was identified using the prediction tool TargetScan v5.1, and luciferase reporter gene assays confirmed that NKCC2A mRNA is directly targeted and repressed by miR‐195. Primary cultures of medullary thick ascending limb (mTAL) cells and freshly isolated mTAL tubules express NKCC2 isoforms A and F. However, only miR‐195 and NKCC2A, but not NKCC2F mRNA, were up‐regulated in mTAL cells exposed for 2 h to a change in osmolality from 300 to 500 mOsmol/kgH₂O, produced with NaCl. Transient transfection of mTAL cells with an shRNA vector targeting TNF prevented increases in miR‐195 induced by high NaCl concentration. Moreover, transfection of a miR‐195 mimic into mTAL cells suppressed NKCC2A mRNA, but not NKCC2F mRNA, by approximately 83% (p<0.05) in cells exposed to high NaCl. In contrast, transfection with anti‐miR‐195 increased NKCC2A mRNA without altering NKCC2F mRNA abundance. Laser‐scanning cytometry detected a 1.5 fold (p<0.05) increase in pNKCC2 protein expression in mTAL cells transfected with anti‐miR‐195, and a miR‐195 mimic prevented the increase of pNKCC2 induced by silencing TNF in cells exposed to high NaCl. Next, we determined whether miRNA‐195 regulates HS‐dependent changes in blood pressure by inhibiting NKCC2A. Both TNF and miR‐195 expression increased in OM from mice given 1% NaCl in the drinking water (HS) for 7 days. Intrarenal injection of a lentivirus construct that specifically silenced TNF in the kidney (U6‐TNF‐ex4) inhibited the expression of miR‐195 (p<0.05), while increasing NKCC2A mRNA expression in mice ingesting HS. However, intrarenal injection of murine recombinant TNF significantly upregulated the expression of miR‐195 and suppressed the increases of NKCC2A mRNA in mice ingesting HS. Intrarenal administration of miR‐195 prevented the increase of NKCC2A mRNA abundance in the OM from mice injected with the TNF silencing lentivirus (U6‐TNF‐ex4) compared with the control lentivirus. Moreover, the HS‐induced increase in blood pressure detected by radiotelemetry after renal silencing of TNF was markedly attenuated in mice given an intrarenal injection of miR‐195. Collectively, the study identifies miR‐195 as a salt‐sensitive and TNF inducible miRNA that inhibits HS‐mediated increases in blood pressure by inhibiting NKCC2A.

Moringa oleifera ethanolic extract attenuates tilmicosin-induced renal damage in male rats via suppression of oxidative stress, inflammatory injury, and intermediate filament proteins mRNA expression

Tilmicosin (Til) is a popular macrolide antibiotic, widely used in veterinary practice. The present study was designed to address the efficacy of Moringa oleifera ethanolic extract (MOE) in protecting against Tilmicosin (Til) - induced nephrotoxicity in Sprague Dawley rats. Animals were treated once with Til (75 mg/kg bw, subcutaneously), and/or MOE for 7 days (400 or 800 mg/kg bw, by oral gavage). Til-treatment was associated with significantly increased serum levels of creatinine, urea, sodium, potassium and GGT activity, as well as decreased total protein and albumin concentrations. Renal tissue hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels were elevated, while the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) enzymes were diminished. The levels of renal tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β) and the mRNA expression of intermediate filament protein encoding genes (desmin, nestin and vimentin) in the kidney were up- regulated with histopathological alterations in renal glomeruli, tubules and interstitial tissue. These toxic effects were markedly ameliorated by co-treatment of MOE with Til, in a dose dependent manner. Taken together, these results indicate that MO at 800 mg/kg protects against Til-induced renal injury, likely by its potent antioxidant and anti-inflammatory properties, which make it suitable to be used as a protective supplement with Til therapy.

Coenzyme Q10 Attenuates Cisplatin-induced Nephrotoxicity Through Counteracting Oxidative Stress and Inflammation

Background: Cisplatin is an anticancer drug used in the management of solid tumors, however, dose-related nephrotoxicity is one of its major problems. Agents having antioxidants, antiinflammatory and/or antiapoptotic activities may thus represent potential therapeutic options to avoid cisplatin-induced nephrotoxicity. Among these agents, coenzyme Q10 has several pharmacological properties including antioxidant, anti-inflammatory and/or anti-apoptotic effects. Objective: The current study aimed to examine whether coenzyme Q10 could attenuate cisplatininduced nephrotoxicity or not. Methods: 24 adult rats were randomly separated into three groups (8 rats per group). The first one was the control group, rats receiving vehicle (olive oil) intraperitoneally. The second group was Cisplatin treated group, rats were receiving 13 mg/kg of Cisplatin intraperitoneally as a single dose. The third group (Cisplatin + Coenzyme Q10), rats were receiving 13 mg/kg as a single intraperitoneal dose of Cisplatin and coenzyme Q10 daily for six consecutive days (10 mg/kg intraperitoneally). Results: Cisplatin caused significant increases in serum creatinine and severe histological lesions. Cisplatin treated group also showed a significant elevation in renal malondialdehyde concentration as a marker of oxidative stress; renal tumor necrosis factor-alpha concentration as a marker of inflammation; and Kidney injury molecule -1 concentration. Coenzyme Q10 significantly attenuated cisplatininduced nephrotoxicity through lowering serum creatinine and improving nephrotoxicity histological scores. Coenzyme Q10 also significantly reduced the renal concentration of MDA, TNF-α and KIM-1 relative to cisplatin treated group. Conclusions: Coenzyme Q10 has a potential nephroprotective effect against cisplatin-induced nephrotoxicity that was demonstrated by biochemical and histopathological analysis.

Abstract P218: Downregulation of Renal Tumor Necrosis Factor-Alpha Production in Response to Hypotonic Stress Facilitates Adaptive Increases in Renal Cortical Angiotensinogen and Nkcc2b

We previously showed that diverse stimuli activate the thick ascending limb of Henle’s loop (TAL) to synthesize tumor necrosis factor-alpha (TNF), which subsequently acts as an endogenous inhibitor of the Na(+)-K(+)-2Cl(-) cotransporter (NKCC2). Moreover, renal-specific silencing of TNF unmasks salt-dependent increases in blood pressure via a mechanism involving NKCC2A. The objective of the present study was to determine the effects of TNF on NKCC2 isoform and angiotensinogen (AGT) expression in the renal cortex under conditions of hypotonic stress. Mice given a low salt (0.02% NaCl) diet (LS) for 7 days exhibited a 62±7.4% decrease (p<0.5, n=4) in TNF mRNA expression in the renal cortex, compared with mice ingesting a normal salt diet (NSD), which was associated with a concomitant 4-fold increase in renal cortical AGT mRNA accumulation (p<0.05, n=4). Mice ingesting LS also exhibited about a 63% increase (p<0.05, n=4) in cortical TAL phospho-NKCC2 (pNKCC2) expression and a 3-fold increase in NKCC2B mRNA abundance without a concurrent change in NKCC2A mRNA accumulation. The increases in AGT and NKCC2B mRNA abundance were increased by 6-fold (p<0.05, n=4 ) and 5-fold (p<0.05, n=4), respectively, in mice ingesting LS that also received an intrarenal injection of a lentivirus construct designed to specifically silence TNF in the kidney (U6-TNF-ex4) compared with mice injected with control lentivirus (U6). The effects of a single intrarenal injection of murine recombinant TNF (5ng/g body weight) or saline control for 24 hr on renal AGT and NKCC2 mRNA levels were then determined in mice that ingested LS for 7 days. Administration of TNF inhibited the increase of AGT and NKCC2B mRNA abundance by approximately 42±5.9% and 49±6.5% respectively, p<0.05, n=4 ) in mice exposed to hypotonic stress. Similarly, intrarenal injection of TNF inhibited the increase in pNKCC2 by approximately 54% (p<0.05, n=4 ) in renal cortex from mice given LS for 7 days. Collectively, these findings suggest that downregulation of renal TNF production in response to hypotonic conditions contributes to the regulation of sodium chloride reabsorption via adaptive increases in AGT as well as a selective effect on NKCC2B, which is exclusively expressed by macula densa cells in the renal cortex.

Intrarenal silencing of TNF facilitates salt‐dependent increases in blood pressure

We previously showed that the thick ascending limb (TAL) produces tumor necrosis factor‐alpha (TNF) in response to diverse stimuli and acts as an endogenous inhibitor of NKCC2. The effect of renal TNF production on blood pressure and adaptation to high NaCl (HS) intake was determined in this study. We designed lentivirus constructs suitable for intrarenal administration and silencing of TNF and the NKCC2A isoform. Silencing of TNF was validated in primary cultures of mTAL cells challenged with high NaCl concentrations. For in vivo silencing of TNF purified U6‐TNF‐ex4, or control lentivirus (U6), was injected directly into each kidney. Three days later qRT‐PCR analysis showed that TNF mRNA was markedly reduced in kidney but not spleen. Accordingly, we administered 1% NaCl in the drinking water to study the intrinsic effects of TNF produced within the kidney on blood pressure regulation under normal and high salt conditions. Baseline SBP was similar in mice ingesting tap water and a normal salt diet (NSD) that were given control lentivirus (U6) and U6‐TNF‐ex4. However, silencing TNF increased SBP (127.9±4.3 mmHg) when mice were switched to 1% NaCl for 3 days compared with mice injected with U6 control (117.6±3.2 mmHg). The increases in blood pressure, which were continuously observed for 7 days and were detected concomitantly with an increase in renal but not systemic TNF production, promptly returned to baseline levels when mice were switched from 1% NaCl to tap water. Renal silencing of TNF also induced a specific 2‐fold increase in NKCC2A mRNA levels while NKCC2B and NKCC2F levels were unchanged. Analysis of daytime and nighttime periods by radiotelemetry showed that silencing of TNF not only increased MAP (108.2±4.1mmHg) compared with control (96.4±2.3 mmHg) during daytime but also increased MAP (118.7±5.0 mmHg) compared with control (107.0±2.9 mmHg) during nighttime in mice ingesting 1% NaCl. Knockdown of TNF in the kidney did not disturb the diurnal regulation of blood pressure but caused a further sensitivity to NaCl‐induced increases in blood pressure in mice with 1 kidney. Importantly, the NaCl‐mediated increases in blood pressure were completely absent when NKCC2A and TNF were concomitantly silenced in the kidney. Additionally, studies were performed using mice placed in metabolic cages that received intrarenal injections of control (U6), U6‐TNF‐ex4, or a mixture of U6‐TNF‐ex4 and U6‐N2A‐ex4. Renal silencing of TNF elicited a decrease in urine volume, sodium, and chloride excretion, while potassium excretion increased compared with mice that received injections of control lentivirus. The diuresis and natriuresis observed in response to renal TNF silencing was abolished when NKCC2A was concurrently silenced suggesting this isoform contributes to the transition from a salt‐resistant to salt‐sensitive phenotype. The data indicate that the effects of renal TNF silencing and the subsequent increase in NKCC2A set in motion changes in transporters that increase diuresis and natriuresis. Collectively, the increase in blood pressure in response to HS when TNF is silenced in the kidney suggests that deficiency of locally derived TNF production is sufficient to render normotensive healthy mice salt‐sensitive as well as alter electrolyte excretion.Support or Funding InformationThis work was supported by grants from NIH R01 HL133077, NYMC/Touro Bridge grant, and the George M. O'Brien Kidney Center at Yale, NIH P30 DK079310.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The liver X receptor agonist TO901317 protects mice against cisplatin-induced kidney injury.

Liver X receptors are in the nuclear receptor superfamily and are contained in the regulation of lipid and cholesterol metabolism. Besides, liver X receptors are considered crucial regulators of the inflammatory response and innate immunity. The current study evaluates the invivo effects that the synthetic liver X receptor agonist TO901317 protects against cisplatin-induced kidney injury in mice. Mice received cisplatin administration through a single intraperitoneal injection (20 mg/kg in saline). And then the mice were treated with the TO901317 by daily gavage (10 mg/kg/day) 12 h postcisplatin administration, and cisplatin nephrotoxicity was evaluated. At 72 h after cisplatin treatment, elevated plasma urea and creatinine levels (P < 0.05) were evidenced which indicates the renal dysfunction of the vehicle-treated mice, consistent with tubular necrosis, protein cast, dilation of renal tubules, and desquamation of epithelial cells in renal tubules. In contrast, the severity of renal dysfunction and histological damage was reduced in TO901317 treated mice (P < 0.05). In accordance, circulating tumor necrosis factor alpha levels, renal tumor necrosis factor alpha, p47(phox), gp91(phox), and protein expression levels and COX-2 mRNA, renal monocyte chemoattractant protein 1, VACAM-1 mRNA and intercellular adhesion molecule-1 contents, and renal prostaglandin E2 amounts, were higher in samples from cisplatin-treated mice in comparison with controls (P < 0.05) but attenuated in the TO901317 treatment group (P < 0.05). Taken together, treatment with the liver X receptor agonist TO901317 ameliorated the inflammatory response and oxidative stress in cisplatin-induced kidney injury in mice.

Effects of combinations of Xiexin decoction constituents on diabetic nephropathy in rats

Ethnopharmacological relevanceXiexin decoction (XXD) has been used as a treatment for diabetes mellitus for more than 1300 years. XXD constituents with protective effects against diabetic nephropathy (DN) include Rhizoma Coptidis alkaloids (RA), Radix et Rhizoma Rhei polysaccharides (RP), and Radix Scutellaria flavones (RF). The aim of the study is to investigate the effects of combinations of RA, RP, and RF on DN and their mechanisms of action. Materials and MethodsIn vitro, high glucose-induced rat mesangial cells were treated with RA, RP, RF, and combinations thereof. Cell proliferation and levels of inflammatory factors were measured. In vivo, high-fat diet and streptozotocin-induced diabetic rats were treated with different combinations of RA, RP, and RF once per day for 12 weeks. Blood and urine biochemical parameters, renal tissue morphology, and inflammation were investigated. ResultsIn vitro, the combination of the three groups of components inhibited mesangial cell proliferation and reduced the levels of monocyte chemotactic protein-1 (MCP-1) and collagen IV. The effects of the three constituent groups in combination were stronger than those of each group alone or combinations of two groups. In diabetic rats, combinations of the three groups of herb components ameliorated blood glucose, urinary albumin excretion and decreased renal mesangial matrix expansion and basement membrane thickening. In addition, the combinations reduced renal tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) protein levels, down-regulated the expression of nuclear factor κB (NF-κB) and transforming growth factor beta 1 (TGF-β1), and up-regulated the expression of inhibitor of nuclear factor κB (IκB) protein. Among the three groups of herb components, RA produced the strongest effects, followed by RP, and then by RF. ConclusionsThe combination of the three groups of herb components produced anti-DN effects through inhibition of inflammation mediated by NF-κB. Among the three groups of herb components, RA produced the strongest effect while RP and RF produced weaker effects.

Protective Effects of Aminophylline on Vancomycin-Induced Acute Kidney Injury in Rats: Anti-Oxidant and Anti-Inflammatory Roles

Background: Vancomycin is currently the antibiotic of choice for serious infections such as methicillin-resistant Staphylococcus aureus (MRSA) and Enterococcus faecium but its usefulness is limited by the development of nephrotoxicity. Aim: The present study was designed to determine the protective roles of aminophylline in vancomycin-induced acute kidney injury (AKI) in rats. Materials and Methods:Male Wister rats (n=40) were used.Vancomycin nephrotoxicity was induced through intraperitoneal injection of vancomycin (200 mg/kg twice daily) for 7 days. Aminophylline was administered once daily in a dose of 24mg/kg alone or combined with vancomycin for 7 days. Results: Vancomycin was observed to cause a severe nephrotoxicity, which was evidenced through increased kidney index, elevated blood urea nitrogen (BUN) and reduced creatinine clearance. Renal malondialdehyde (MDA) levels were significantly increased with marked decrease in renal reduced glutathione (GSH) levels as well as renal superoxide dismutase (SOD) and catalase activities. Moreover, elevated renal tumor necrosis factor-alpha (TNF-α) and low renal interleukin-10 (IL-10) levels were observed. Prior aminophylline administration to rats treated with vancomycin showed significant reduction in kidney index and BUN with elevation in creatinine clearance. In addition, aminophylline reduced elevated renal MDA and TNF-α levels and promoted renal GSH levels in addition to renal SOD and catalase activities with upregulation of renal IL-10. Conclusions: Oxidative stress and inflammation are remarkable pathways in the pathogenesis of vancomycin induced AKI. Aminophylline could be used in a prophylactic manner in vancomycin associated acute renal injury.

Cytoprotective Actions of FTY720 Modulate Severe Preservation Reperfusion Injury in RatRenal Transplants

Fingolimod (FTY720) is a potent agonist of sphingosine 1 phosphate receptors and thereby interferes with lymphocyte trafficking. We previously showed that FTY720 protects from mild preservation reperfusion injury induced by 4 hr of cold ischemia. The purpose of this study was to explore the role of FTY720 in ischemic injury and regeneration using a clinically relevant rat renal transplant model with 24 hr of cold ischemia. Donor kidneys were cold stored in the University of Wisconsin solution for 24 hr before transplantation into bilaterally nephrectomized syngeneic recipients (n=6 per group), which received 0.5 mg/kg/d FTY720 or vehicle through oral gavage. Grafts were harvested 2 or 7 days posttransplantation. Renal tissue was examined histologically, stained for apoptosis, proliferation, inflammatory cell infiltrates, and studied for transforming growth factor-beta, and tumor necrosis factor-alpha expression. Rat proximal tubular cells were incubated with 0.1 to 30 micromol/L of phosphorylated FTY720 to test for in vitro cytopathic effects. FTY720 induced peripheral lymphopenia and significantly reduced intragraft CD3 and ED1 infiltrates. Acute tubular damage scores and graft function were not influenced by FTY720. Tubular apoptosis was significantly reduced, whereas the number of proliferating cell nuclear antigen-positive tubular cells were markedly increased. FTY720 attenuated renal tumor necrosis factor-alpha and transforming growth factor-beta expression. In vitro, pharmacologic concentrations up to 1 micromol/L of phosphorylated FTY720 did not affect tubular cell viability. FTY720 confers tubular epithelial protection in the presence of severe preservation reperfusion injury. Beneficial effects may in part be due to reduction in cell-mediated immune mechanisms. Furthermore, FTY720 could be helpful in patients with delayed graft function.

Effects of Soy Protein Hydrolysate on Blood Pressure and Angiotensin-Converting Enzyme Activity in Rats with Chronic Renal Failure

We investigated the effects of soy protein and soy protein hydrolysate on blood pressure control, angiotensin-converting enzyme (ACE) activity, and renal function in a rat chronic renal failure model. Rats that had undergone a 5/6 nephrectomy were separated into three groups and fed different experimental diets for 14 weeks. At the end of the study, rats that fed a diet containing soy protein as the protein source had better blood pressure control and renal function, as well as lower circulating ACE activity and renal tumor-necrosis factor-alpha (TNF-alpha) concentration than rats fed a casein protein diet. Soy protein hydrolysate was shown to be as effective as soy protein in preventing the elevation of blood pressure, the progression of renal failure, and decreases in kidney TNF-alpha level, plasma ACE activity, and insulin concentration. In conclusion, the beneficial effects of consuming soy protein on blood pressure and renal function may be mediated mostly by its pepsin-digested hydrolysate through its ACE inhibitory activity.

A pathogenic role for JNK signaling in experimental anti-GBM glomerulonephritis

Activation of the c-Jun NH2-terminal kinase (JNK) signaling pathway is involved in the immune response; however, little is known of its role in immune-induced renal injury. In this study, we examine JNK signaling in the rat anti-glomerular basement membrane (GBM) disease model using CC-401, a specific JNK inhibitor. Animals were given CC-401, vehicle alone or no treatment starting before anti-GBM serum injection and continued treatment until killing. In acute disease, CC-401 blocked JNK signaling and reduced proteinuria in the first 24 h. The transient neutrophil influx seen at 3 h of disease was not affected, however. Continued CC-401 treatment suppressed glomerular and tubulointerstitial damage usually seen at 14 days. The protective effect may be due to modulation of macrophage activation, as CC-401 had no effect upon glomerular macrophage infiltration at day 14 despite the suppression of glomerular lesions and a marked reduction in renal tumor necrosis factor-alpha and inducible nitric oxide synthase messenger RNA levels. Treatment with CC-401 had no apparent effect on T cell or humoral immune responses. These studies suggest that JNK signaling promotes renal injury in acute and progressive rat anti-GBM disease. JNK inhibitors may be a novel therapeutic approach for the treatment of human glomerulonephritis.

Effect of anemia and renal cytokine production on erythropoietin production during blood-stage malaria

Renal dysfunction and severe anemia are clinical complications of blood-stage malaria. Erythropoietin (Epo) is a hormone produced by the kidney and plays an essential role in stimulating erythrocyte production. Renal dysfunction in malaria is associated with changes in renal cytokine levels, which may affect the production of Epo and the alleviation of anemia. Resistant C57BL/6 (B6) and susceptible A/J mice were infected with Plasmodium chabaudi AS. The levels of Epo and cytokines were measured by enzyme-linked immunosorbent assay (ELISA) and the degree of anemia was determined by hematocrit. Regression analyses were employed to estimate the influences of anemia and renal cytokines on the production of Epo during infection. A/J mice developed higher peak parasitemia, more severe anemia, and succumbed as compared to B6 mice, which survived the infection. B6 mice had higher levels of renal tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-10, whereas A/J mice had higher levels of IL-12p70, granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-4, and Epo. Regression analyses revealed that kidney Epo levels were influenced most strongly by changes in hematocrit levels. In addition, albeit to a much weaker degree, kidney Epo levels correlated negatively with GM-CSF levels but positively with IL-10 levels. Blood-stage malaria infection modulates the production of renal pro- and anti-inflammatory cytokines in resistant versus susceptible strains of mice differentially. However, despite the fluctuations of renal cytokines, the degree of anemia is the main determinant for Epo production during blood-stage malaria while kidney cytokines may exert secondary influences.

Functional protection by acute phase proteins alpha(1)-acid glycoprotein and alpha(1)-antitrypsin against ischemia/reperfusion injury by preventing apoptosis and inflammation.

Ischemia followed by reperfusion (I/R) causes apoptosis, inflammation, and tissue damage leading to organ malfunction. Ischemic preconditioning can protect against such injury. This study investigates the contribution of the acute phase proteins alpha(1)-acid glycoprotein (AGP) and alpha(1)-antitrypsin (AAT) to the protective effect of ischemic preconditioning in the kidney. Exogenous AGP and AAT inhibited apoptosis and inflammation after 45 minutes of renal I/R in a murine model. AGP and AAT administered at reperfusion prevented apoptosis at 2 hours and 24 hours, as evaluated by the presence of internucleosomal DNA cleavage, terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling, and the determination of renal caspase-1- and caspase-3-like activity. AGP and AAT exerted anti-inflammatory effects, as reflected by reduced renal tumor necrosis factor-alpha expression and neutrophil influx after 24 hours. In general, these agents improved renal function. Similar effects were observed when AGP and AAT were administered 2 hours after reperfusion but to a lesser extent and without functional improvement. Moreover, I/R elicited an acute phase response, as reflected by elevated serum AGP and serum amyloid P (SAP) levels after 24 hours, and increased hepatic acute phase protein mRNA levels after 18 hours of renal reperfusion. We propose that the antiapoptotic and anti-inflammatory effects of AGP and AAT contribute to the delayed type of protection associated with ischemic preconditioning and other insults. This mechanism is potentially involved in the course of many clinical conditions associated with I/R injury. Moreover, exogenous administration of these proteins may provide new therapeutic means of treatment.

EARLY RENAL ISCHEMIA, WITH OR WITHOUT REPERFUSION, ACTIVATES NFκB AND INCREASES TNF-α BIOACTIVITY IN THE KIDNEY

Acute tubular necrosis (ATN) and the ensuing renal failure induced by ischemia and reperfusion injury (I/R) remain a major cause of morbidity and mortality among patients in the intensive care unit. Although it is well established that exogenous tumor necrosis factor-alpha (TNF) induces renal injury, it remains unknown whether ischemia and/or reperfusion activates the signaling mechanisms required for renal TNF production. We hypothesized that ischemia and/or reperfusion would activate the oxidant sensitive TNF transcription factor, nuclear factor kappa B (NFkappaB), and thereby lead to renal TNF production. Male Sprague-Dawley rats were anesthetized with sodium pentobarbital, after which various periods of renal ischemia, with or without reperfusion, were induced in rats. At different time intervals, kidneys were harvested and NFkappaB activation (electrophoretic mobility shift assay), TNF mRNA content (RT-PCR), and TNF bioactivity (WEHI-164 cell clone cytotoxicity assay) were determined. Results indicate that 15 minutes of ischemia alone activates NFkappaB, whereas peak activation occurred at 30 minutes of ischemia alone. NFkappaB remained activated through 60 minutes reperfusion. Thirty minutes of ischemia is required to induce renal TNF mRNA production; however, renal TNF protein expression and bioactivity peaked following 1 hour of ischemia and 2 hours reperfusion. These results are the initial demonstration that renal ischemia, with or without reperfusion, activates the TNF transcription factor NFkappaB and increases TNF bioactivity in the kidney.