Pentoxifylline protects against endotoxin-induced acute renal failure in mice

Pentoxifylline and thiamine ameliorate rhabdomyolysis-induced acute kidney injury in rats via suppressing TLR4/NF-κB and NLRP-3/caspase-1/gasdermin mediated-pyroptosis

Acute kidney injury (AKI) is a common complication of rhabdomyolysis (RM), a syndrome characterized by skeletal muscle damage resulting in renal tubular oxidative stress, inflammation, and activated toll like receptor-4 (TLR-4) and NOD-like receptor protein-3 (NLRP-3) inflammasome. Pyroptosis is a programmed cell death mediated by NLRP-3 leading to the activation of caspase-1 and gasdermin D (GSDMD), the hallmark of pyroptosis. This study aims to investigate the renoprotective effects of two antioxidants; pentoxifylline (PTX) and thiamine (TM) via targeting the aforementioned pathways. RM-AKI was induced in male Albino Wistar rats by intramuscular injection of glycerol (50% v/v, 10 ml/kg). PTX (100 mg/kg, oral) and TM (25 mg/kg, i.p) were administered for 12 days prior glycerol injection and continued for 3 days following induction of RM-AKI. Serum creatinine, blood urea nitrogen (BUN), creatin kinase, lipid peroxides, total antioxidant activity, inflammatory markers (tumor necrosis factor-α, interleukin-1β, and nuclear factor kappa B), TLR4, NLRP-3, caspase-1, GSDMD and c-myc (an apoptotic marker) were estimated. Compared to AKI model, co-administered drugs revealed a significant improvement in renal function and pathology as indicated by the reduction in serum creatinine, BUN and protein cast accumulation. The elevations of oxidative stress, and inflammatory markers as well as the over-expression of c-myc were alleviated. Protein levels of TLR4, NLRP3, cleaved caspase-1, and GSDMD were significantly elevated in RM-AKI model, and this elevation was attenuated by the tested drugs. In conclusion, PTX and TM could be a potential renoprotective approach for patients with RM through targeting TLR4/NF-κB and NLRP-3/caspase-1/gasdermin mediated-pyroptosis pathways.

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

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

Protective effect of pentoxifylline on oxidative renal cell injury associated with renal crystal formation in a hyperoxaluric rat model

The aim of the study is to investigate the effects of pentoxifylline (PTX) on the renal tubular cell injury and stone formation in a hyperoxaluric rat model induced by ethylene glycol and its possible underlying mechanisms. The study was performed with 30 male Wistar rats and randomized into three groups of teen. The sham-control (group 1) received only drinking water orally. The EG/untreated (group 2) received drinking water containing 0.75% EG for 4 weeks orally. The EG/PTX treated (group 3) received drinking water containing 0.75% EG for 4 weeks orally and PTX. Urine and blood were collected to determine some parameters. The kidneys were also removed for histological examination. Serum and urinary parameters were significantly improved in the EG/PTX treated. In the EG/PTX-treated group, the MDA, TOS and MPO activity reduced and the TAS, SOD, CAT and GSH-Px activities were increased markedly compared with the group 2. In urine of the group 2 rats, a large number of CaOx crystals were displayed and most tubules that contained crystals were dilated and showed degeneration, necrosis, and desquamation of the lining epithelium. Only few CaOx crystals were r in EG/PTX-treated animal's urine. Mild tissue damage was observed in PTX-treated rats. iNOS expression was significantly elevated in the group 2. In contrast, in the EG/PTX-treated group, eNOS expression in renal tubular epithelial cells was increased. Current study indicates that PTX may partially reduce renal tubular injury resulting from hyperoxaluria-induced oxidative and nitrosative stress.

Differences in acute kidney injury ascertainment for clinical and preclinical studies

Background

Acute kidney injury (AKI) is a common clinical condition directly associated with adverse outcomes. Several AKI biomarkers have been discovered, but their use in clinical and preclinical studies has not been well examined. This study aims to investigate the differences between clinical and preclinical studies on AKI biomarkers.

Methods

We performed a systematic review of clinical and preclinical interventional studies that considered AKI biomarkers in enrollment criteria and/or outcome assessment and described the main differences according to their setting, the inclusion of biomarkers in the definition of AKI and the use of biomarkers as primary or secondary end points.

Results

In the 151 included studies (76 clinical, 75 preclinical), clinical studies have prevalently focused on cardiac surgery (38.1%) and contrast-associated AKI (17.1%), while the majority of preclinical studies have focused on ether ischemia-reperfusion injury or drug-induced AKI (42.6% each). A total of 57.8% of clinical studies defined AKI using the standard criteria and only 19.7% of these studies used AKI biomarkers in the definition of renal injury. Conversely, the majority of preclinical studies defined AKI according to the increase in serum creatinine and blood urea nitrogen, and 32% included biomarkers in that definition. The percentage of both clinical and preclinical studies with biomarkers as a primary end point has not significantly increased in the last 10 years; however, preclinical studies are more likely to use AKI biomarkers as a primary end point compared with clinical studies [odds ratio 2.31 (95% confidence interval 1.17-4.59); P  =  0.016].

Conclusion

Differences between clinical and preclinical studies are evident and may affect the translation of preclinical findings in the clinical setting.

Hepatocyte SHP-1 is a Critical Modulator of Inflammation During Endotoxemia

Liver hepatocytes (Hep) are known to be central players during the inflammatory response to systemic infection. Interestingly, the protein tyrosine phosphatases (PTP) SHP-1, has been recognized as a major regulator of inflammation; however their implication in the control of Hep-mediated inflammatory response is still unknown. To study its implication in the regulation of the Hep-mediated inflammatory response during endotoxemia, Cre-Lox mice with a Hep-specific Ptpn6 deletion (Ptpn6^H-KO) were injected with LPS. In contrast to the wild-type mice (Ptpn6^f/f) that started to die by 24 hrs post-inoculation, the Ptpn6^H-KO mice exhibited mortality by 6 hrs. In parallel, higher amounts of metabolic markers, pro-inflammatory mediators and circulating cytokines were detected in Ptpn6^H-KO mice. Primary Hep obtained from Ptpn6^H-KO, also showed increased secretion of pro-inflammatory cytokines and nitric oxide (NO) comparatively to its wild type (Ptpn6^f/f) counterpart. Pharmacological approaches to block TNF-α and NO production protected both the Ptpn6^f/f and the Ptpn6^H-KO mice against deadly LPS-mediated endotoxemia. Collectively, these results establish hepatocyte SHP-1 is a critical player regulating systemic inflammation. Our findings further suggest that SHP-1 activation could represent a new therapeutic avenue to better control inflammatory-related pathologies.

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

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

Nitric oxide synthase in diabetic rat testicular tissue and the effects of pentoxifylline therapy

Diabetes is known to be associated with erectile dysfunction, retrograde ejaculation, level of testicular hormone, and a decrease in semen quality, respectively. In this project, we aimed to investigate at the molecular level, the effects of NOS on testes pathology in diabetes and examine the effects of pentoxifylline on healing. A total of 50 Wistar albino male rats were divided into five groups: Group I control; Group II only diabetes; Group III and IV diabetes + pentoxifylline; Group V only pentoxifylline. Group III rats received 50 mg/kg/day pentoxifylline during two months. In comparison, Group IV rats received saline in the first month followed by 50 mg/kg/day of pentoxifylline for the following month. NOS expression in testicular tissue was assessed using qRT-PCR, western blot, and immunohistochemistry. The mean seminiferous tubule diameter, Johnsen's testicular biopsy score, and serum testosterone levels decreased compared to controls. In contrast, the number of apoptotic cells, the levels of nNOS, iNOS and eNOS mRNA, and protein increased when compared to the control. Upon pentoxifylline therapy NOS decreased suggesting that it contributes to this damage and treatment with pentoxifylline may be effective in reversing this damage.

Therapeutic effects of pentoxifylline on diabetic heart tissue via NOS

Objective:

Diabetes mellitus causes a decrease in cardiac output, arterial blood pressure, and heart rate. In this study, we aimed to investigate, at the molecular level, the effect of nitric oxide synthase (NOS) on heart pathology in type 1 diabetes and look at the therapeutic effect of pentoxifylline on this pathology.

Methods:

In this experimental study, 50 Wistar albino male rats were used. The rats were divided into 5 groups: group C, control; group D, only diabetes; group D+PI and D+PII, diabetes + pentoxifylline; group P, only pentoxifylline. Group D+PI rats received 50 mg/kg/day pentoxifylline over two months. However, group D+PII rats received saline in the first month and 50 mg/kg/day of pentoxifylline over the following month. At the end of two months, NOS expressions in heart tissue were assessed through immunohistochemistry analysis. The data were compared by one-way ANOVA.

Results:

At the end of the experiments, there was increased cytoplasmic vacuolization, myofibrillar loss, cytoplasmic eosinophilia, and degeneration of cardiomyocytes; nNOS and iNOS expressions in group D decreased compared with that in group C. In group D+PI and group D+PII, nNOS and iNOS expressions improved compared with group D.

Conclusion:

As a result, we found that diabetes, a known chronic disease, causes serious damage in heart tissue. NOS plays a role in this damage, and pentoxifylline aided in improving nNOS and iNOS expression in this damage.

Attenuating effect of Ginsenoside Rb1 on LPS-induced lung injury in rats

BACKGROUND

Sepsis causes neutrophil sequestration in the lung which leads to acute lung injury (ALI). Radix Ginseng (RG), a traditional herb used as herbal remedy in eastern Asia for thousands of years, which has been traditionally used in China to improve blood circulation and ameliorate pathological hemostasis. This study investigated whether Ginsenoside Rb1, the main components of RG, can attenuate ALI induced by LPS.

METHODS

In vivo, 30 male Wistar rats were divided into three groups (n = 10 each groups) on the basis of the reagent used, which were subjected to LPS injection with or without Ginsenoside Rb1 (5 mg/kg) treatments to induce ALI model. Lung injury was assessed by pulmonary histology, lung wet-weight to dry-weight (W/D) ratio, the number of myeloperoxidase (MPO) positive cells, immunohistochemical analysis of intercellular adhesion molecule-1 (ICAM-1), gene expression of ICAM-1, ultrastructure changes of pulmonary microvasculature, concentration of inflammatory markers and in plasma. In vitro, pulmonary microvascular endothelial cells (PMVECs) were stimulated with LPS in the presence and absence of Ginsenoside Rb1 (50 mM), nuclear factor-κB (NF-κB) p65 was measured by immunocytochemistry staining and western blotting.

RESULTS

Infusion of LPS induced lung injury, in vivo, as demonstrated by pulmonary edema with infiltration of neutrophils and hemorrhage, the increase in lung W/D ratio, the number of MPO positive cells, the level of inflammatory markers such as TNF-α, MCP-1 and IL-8, enhanced expression of ICAM-1 and ICAM-1 gene. Moreover, resulted in the changes of intercellular junctions in the endothelial cells of pulmonary microvasculature. In vitro, the significant increased release of NF-κB p65 and its subsequent translocation into the nucleus in PMVECs were observed. In contrast, Ginsenoside Rb1 treatment significantly ameliorated the LPS-induced lung injury, as judged by the marked improvement in all these indices.

CONCLUSIONS

These results indicate that Ginsenoside Rb1 attenuated LPS-induced lung injury through an inhibition of the inflammatory signaling pathway, besides the direct inhibitory effect on proinflammatory molecules.

Effects of ghrelin on sepsis-induced acute kidney injury: one step forward

BACKGROUND

Among the several disorders induced by sepsis, acute kidney injury (AKI) represents the most important economic burden problem that is associated with high mortality and morbidity rates. The aim of this study was to investigate the anti-inflammatory effects of ghrelin in sepsis-induced AKI and the possible role of vagus nerve.

METHODS

Five groups were included: sham, cecal ligation and puncture (CLP), CLP-ghrelin, CLP-vagotomy and CLP-vagotomy-ghrelin group.

RESULTS

Ghrelin treatment immediately after induction of CLP, significantly improved renal Glomerular filtration rate (GFR), serum creatinine, BUN and renal necrosis score as compared to the unprotected CLP group. In addition, ghrelin significantly decreased renal TNF alpha (111.5 ± 10.35 vs. 291.8 ± 15.8 pg/mg ptn), VCAM1 (6.28 ± 1.7 vs. 12.9 ± 1.2 µ/g ptn) and MPO (0.95 ± 0.13 vs. 2.5 ± 0.4 µ/g ptn) without significant increase in renal IL-10. Those effects were abolished by vagotomy.

CONCLUSION

We concluded that ghrelin could represent new therapeutic window in early treatment of sepsis-induced AKI and this could be mainly due to its anti-inflammatory effects.

Improving effect of Sivelestat on lipopolysaccharide-induced lung injury in rats

Sepsis causes neutrophil sequestration in the lung, which leads to acute lung injury (ALI). Neutrophil elastase (NE) is thought to play an important role in the pathogenesis of ALI. This study investigated whether Sivelestat, a specific NE inhibitor, can attenuate ALI induced by lipopolysaccharide (LPS). In vivo, 30 male Wistar rats were divided into three groups (n = 10 each groups) on the basis of the reagent used, which were subjected to LPS injection with or without Sivelestat treatments to induce ALI model. Lung injury was assessed by pulmonary histology, lung wet-weight to dry-weight (W/D) ratio, immunohistochemical analysis of intercellular adhesion molecule-1 (ICAM-1), the number of myeloperoxidase (MPO)-positive cells, and gene expression of ICAM-1. In vitro, pulmonary microvascular endothelial cells (PMVECs) were stimulated with LPS in the presence and absence of Sivelestat; nuclear factor-κB (NF-κB) p65 was measured by immunocytochemistry staining and Western blotting. Infusion of LPS induced lung injury, in vivo, as demonstrated by pulmonary edema with infiltration of neutrophils, the increase in lung W/D ratio, the number of MPO-positive cells and enhanced expression of ICAM-1 and ICAM-1 gene. In vitro, the significant increased release of NF-κB p65 and its subsequent translocation into the nucleus in PMVECs. In contrast, Sivelestat treatment significantly ameliorated the LPS-induced lung injury, as judged by the marked improvement in all these indices. These results indicated that inhibition of NE attenuated LPS-induced lung injury through an inhibition of the inflammatory signaling pathway, besides the direct inhibitory effect on NE.

The effects of intraperitoneal pentoxifylline treatment in rat pups with hypoxic-ischemic encephalopathy

BACKGROUND

The aim of this study was to evaluate the effects of postischemic treatment with pentoxifylline on the cytokine gene expressions and neuronal apoptosis in neonatal rat model of hypoxic-ischemic encephalopathy.

METHODS

Seven-day-old Wistar rat pups (n = 40) of either sex, delivered spontaneously, were used in this experimental study. Control group (n = 8): after median neck incision was made, neither ligation nor hypoxia was performed, ischemia group (n = 16): 0.5 mL of saline was injected intraperitoneally immediately after hypoxia. Pentoxifylline and ischemia groups (n = 16): the rat pups were administered intraperitoneally 60 mg/kg of pentoxifylline immediately after hypoxia. Eight rats from ischemia and pentoxifylline + ischemia groups were sacrificed 4 and 24 hours after drug administration. Control group mice were decapitated 4 hours after hypoxia. Caspase-3 activity, interleukin-1β, and tumor necrosis factor-α messenger RNA expression levels were studied in the left half of the brain.

RESULTS

Induction of cerebral ischemia increased tumor necrosis factor-α and interleukin-1β messenger RNA expression levels significantly at 4 hours and 24 hours following ischemia in the left ischemic hemispheres in the ischemia group as compared with the control group. Systemic administration of pentoxifylline immediately after hypoxic-ischemic encephalopathy significantly reduced the tumor necrosis factor-α and interleukin-1β messenger RNA expression levels in ischemic tissue as compared with the ischemia group. Caspase-3 activities in the left half of the brains of ischemia group were found to be increased significantly as compared with control group. Caspase-3 activities in the brains of pentoxifylline + ischemia groups were significantly lower than in that of ischemia group.

CONCLUSIONS

Based on the significantly lower interleukin-1β and tumor necrosis factor-α gene expression measured after 4 and 24 hours and significantly reduced caspase-3 activity measured colorimetrically in the animals treated with pentoxifylline, our findings suggest that pentoxifylline may reduce brain damage due to hypoxic-ischemic injury.

Rolipram improves renal perfusion and function during sepsis in the mouse

Microcirculatory dysfunction is correlated with increased mortality among septic patients and is believed to be a major contributor to the development of acute kidney injury (AKI). Rolipram, a selective phosphodiesterase 4 (PDE4) inhibitor, has been shown to reduce microvascular permeability and in the kidney, increase renal blood flow (RBF). This led us to investigate its potential to improve the renal microcirculation and preserve renal function during sepsis using a murine cecal ligation and puncture (CLP) model to induce sepsis. Rolipram, tested at doses of 0.3-10 mg/kg i.p., acutely restored capillary perfusion in a bell-shaped dose-response effect with 1 mg/kg being the lowest most efficacious dose. This dose also acutely increased RBF despite transiently decreasing mean arterial pressure. Rolipram also reduced renal microvascular permeability. It is noteworthy that delayed treatment with rolipram at 6 hours after CLP restored the renal microcirculation, reduced blood urea nitrogen and serum creatinine, and increased glomerular filtration rate at 18 hours. However, delayed treatment with rolipram did not reduce serum nitrate/nitrite levels, a marker of nitric oxide production, nor reactive nitrogen species generation in renal tubules. These data show that restoring the microcirculation with rolipram, even with delayed treatment, is enough to improve renal function during sepsis despite the generation of oxidants and suggest that PDE4 inhibitors should be evaluated further for their ability to treat septic-induced AKI.

TRPV1 ablation aggravates inflammatory responses and organ damage during endotoxic shock

To test the hypothesis that ablation of transient receptor potential vanilloid type 1 (TRPV1) channels leads to exacerbated inflammatory responses and organ damage during endotoxic shock, lipopolysaccharide (LPS; 5 million endotoxin units/kg of body weight) was injected intraperitoneally (i.p.) into wild-type (WT) and TRPV1-null mutant (TRPV1(-/-)) mice. Mean arterial pressure and heart rate, determined by radiotelemetry, were severely depressed after LPS injection into WT and TRPV1(-/-) mice, with no distinction between the two strains. At 24 h after LPS injection, renal glomerular hypercellularity and hepatocellular injury were observed in both strains, accompanying further elevated serum levels of creatinine and alanine aminotransferase in TRPV1(-/-) mice compared to those in WT mice. At 6 or 24 h after LPS injection, neutrophil recruitment into kidneys and livers, serum cytokine (tumor necrosis factor alpha [TNF-α], interleukin 1β [IL-1β], IL-6) and renal chemokine (KC, macrophage inflammatory protein 2 [MIP-2]) levels, and renal VCAM-1 and ICAM-1 expression were greater in TRPV1(-/-) mice than WT mice. In addition, increased plasma calcitonin gene-related peptide (CGRP) levels observed in WT mice 6 h after LPS injection were absent in TRPV1(-/-) mice. Thus, TRPV1 ablation aggravates inflammatory responses, including neutrophil infiltration, proinflammatory cytokine production, and adhesion molecule expression, leading to intensified organ damage during endotoxic shock in the absence of worsened circulatory failure. The data indicate that TRPV1 activation may attenuate endotoxin-induced organ damage, possibly via its anti-inflammatory action rather than alteration of hemodynamics.

Therapeutic effect of captopril, pentoxifylline, and cordyceps sinensis in pre-hepatic portal hypertensive rats

BACKGROUND/AIM

Portal hypertension is an important and potentially fatal complication of liver disease whereby cellular and fibrotic alterations manifest to increase portal venous pressure. The aim of this study is to investigate the effect of captopril, pentoxifylline (PTX), and cordyceps sinensis in pre-hepatic portal hypertensive rats.

SETTINGS AND DESIGN

Wistar male rats were divided at random into 3 main groups: the first group: control rats. The second group: sham-operated rats and the third group: prehepatic portal hypertensive rats (PHPHT) induced by regulated pre-hepatic portal vein ligation. After 14 days, Group 3 was subdivided into 5 subgroups. Subgroup (1): portal vein-ligated (PVL) was killed at once; Subgroup (2): received distilled water for 30 days (untreated PVL group); subgroups 3-5 were treated with captopril (60 mg/kg, orally); PTX (100 mg/kg, orally); and C. sinensis (200 mg/kg, orally), respectively, as a single daily dose for 30 days.

PATIENTS AND METHODS

Portal pressure, nitric oxide (NO), antioxidant enzymes, Liver enzymes, and creatinine levels were measured to evaluate the status of the liver state.

RESULTS

Portal vein ligation produced significant increments in liver enzymes, NO, creatinine and portal pressure concomitant with significant decrements in glutathione content and superoxide dismutase activity. Treatment with captopril, PTX, and C. sinensis resulted in a significant reduction in liver enzymes, NO, creatinine and portal pressure and observable increase in antioxidant enzymes.

CONCLUSIONS

captopril, PTX, and C. sinensis have promising effect in controlling PHPHT and reducing hyperdynamic circulatory state through reduction of portal pressure and NO level.

Involvement of nitric oxide on the pathogenesis of irinotecan-induced intestinal mucositis: role of cytokines on inducible nitric oxide synthase activation

PURPOSE

Intestinal mucositis and the closely associated diarrhea are common costly side effects of irinotecan. Cytokine modulators, such as thalidomide and pentoxifylline, are found capable of attenuating intestinal mucositis progression. Nitric oxide (NO) seems to be a key mediator of the antineoplastic drug toxicity. The aim of this study was to investigate the role of NO on the pathogenesis of intestinal mucositis, as well as the participation of cytokines upon inducible nitric oxide synthase (iNOS) expression in irinotecan-induced intestinal mucositis.

METHODS

iNOS-knockout (iNOS(-/-)) and C57BL/6 (WT, wild type) animals (n = 5-6) were given either saline or irinotecan (60 mg/kg i.p for 4 days), with or without pretreatment with aminoguanidine (50 mg/kg s.c.), thalidomide (60 mg/kg s.c), infliximab (5 mg/kg i.v.), or pentoxifylline (1.7 mg/kg s.c). On day 5, diarrhea was assessed, and following euthanasia, proximal intestinal samples were obtained for myeloperoxidase (MPO) and iNOS activity, morphometric analysis, western blot and immunohistochemistry to iNOS, cytokine dosage, and for in vitro evaluation of gut contractility.

RESULTS

Irinotecan induced severe diarrhea and intestinal smooth muscle over-contractility, accompanied with histopathological changes. Additionally, increased MPO and iNOS activity and iNOS immunoexpression were found in WT animals treated with irinotecan. The rise in MPO, smooth muscle over-contractility, and diarrhea were abrogated in aminoguanidine-treated and iNOS(-/-) mice. Moreover, through western blot, we verified that infliximab and pentoxifylline significantly inhibited irinotecan-induced iNOS expression. In addition, cytokine concentration was found only partially decreased in irinotecan-treated iNOS(-/-) mice when compared with wild-type animals that were given irinotecan.

CONCLUSIONS

This study suggests a role of nitric oxide in the pathogenesis of irinotecan-induced intestinal mucositis and also provides evidence for the participation of cytokines on iNOS induction.

The individual survival benefits of tumor necrosis factor soluble receptor and fluid administration are not additive in a rat sepsis model

BACKGROUND

Tumor necrosis factor (TNF) antagonists [e.g., TNF soluble receptor (TNFsr)] improved survival in preclinical but not clinical sepsis trials. However fluid support-itself beneficial-is standard clinically but rarely employed in preclinical sepsis models. We hypothesized that these therapies may not have additive benefit.

METHODS AND RESULTS

Antibiotic-treated rats (n = 156) were randomized to intratracheal or intravenous Escherichia coli challenges (>LD50) and either placebo or TNFsr and 24 h fluid treatments alone or together. The survival effects of these therapies did not differ significantly comparing challenge routes. When averaged across route, while TNFsr or fluid alone decreased the hazard ratio of death significantly [ln ± standard error (SE): -0.65 ± 0.30 and -0.62 ± 0.30, respectively, p ≤ 0.05], together they did not (p = 0.16). Furthermore, the observed effect of TNFsr and fluid together on reducing the hazard ratio was significantly less than estimated (-0.37 ± 0.29 versus -1.27 ± 0.43, respectively, p = 0.027) based on TNFsr and fluid alone. While each treatment increased central venous pressure at 6 and 24 h, the observed effects of the combination were also less than estimated ones (p ≤ 0.0005).

CONCLUSIONS

The individual survival benefits of TNFsr and fluids were not additive in this rat sepsis model. Investigating new sepsis therapies together with conventional ones during preclinical testing may be informative.

Methylxanthines and the kidney

This chapter describes the effects of the natural methylxanthines caffeine and theophylline on kidney function. Theophylline in particular was used traditionally to increase urine out put until more potent diuretics became available in the middle of the last century. The mildly diuretic actions of both methylxanthines are mainly the result of inhibition of tubular fluid reabsorption along the renal proximal tubule. Based upon the use of specific adenosine receptor antagonists and the observation of a complete loss of diuresis in mice with targeted deletion of the A1AR gene, transport inhibition by methylxanthines is mediated mainly by antagonism of adenosine A1 receptors (A1AR) in the proximal tubule. Methylxanthines are weak renal vasodilators, and they act as competitive antagonists against adenosine-induced preglomerular vasoconstriction. Caffeine and theophylline stimulate the secretion of renin by inhibition of adenosine receptors and removal of the general inhibitory brake function of endogenous adenosine. Since enhanced intrarenal adenosine levels lead to reduced glomerular filtration rate in several pathological conditions theophylline has been tested for its therapeutic potential in the renal impairment following administration of nephrotoxic substances such as radiocontrast media, cisplatin, calcineurin inhibitors or following ischemia-reperfusion injury. In experimental animals functional improvements have been observed in all of these conditions, but available clinical data in humans are insufficient to affirm a definite therapeutic efficacy of methylxanthines in the prevention of nephrotoxic or postischemic renal injury.

Immunomodulatory properties of pentoxifylline are mediated via adenosine-dependent pathways

The phosphodiesterase inhibitor pentoxifylline (PTX) exerts multiple beneficial immunomodulatory effects in states of hyperinflammation. However, the exact mechanism of action still remains elusive, and the clinical effects of PTX cannot be reliably predicted. In immune cells, the G protein-coupled adenosine A2A receptor (A2AR) exerts strong anti-inflammatory effects. As PTX amplifies signaling pathways downstream of Gs protein-coupled receptors, the A2AR-signaling pathway might be involved in the mediation of immune-suppressive effects of PTX. Here, we investigated this assumption in LPS-stimulated human polymorphonuclear (PMN) leukocytes and in anti-CD3/CD28-stimulated human T cells. In stimulated PMN leukocytes, PTX treatment led to a 4.5-fold decrease of the 50% inhibitory concentrations of adenosine on the H2O2 production; i.e., for adenosine plus PTX (in clinically relevant concentrations), an overadditive increase of inhibitory effects from less than 20% (estimated for each) to 56% (+/-5%) was found. In T cells, adenosine plus PTX revealed similar synergistic inhibitory effects on proinflammatory cytokine production. Inhibition of interferon gamma and TNF-alpha production increased from 7% (+/-1%) and 31% (+/-6%) (PTX alone) to 49% (+/-2%) and 69% (+/-6%), respectively. In T cells and PMN leukocytes, mRNA transcription of the A2AR was significantly increased upon stimulation, which was not influenced by PTX. In human PMN leukocytes and T cells, clinically relevant anti-inflammatory effects of PTX can be achieved only in the presence of sufficient adenosine concentrations. Sufficient adenosine levels might be a prerequisite for the accessibility of sepsis patients to treatment with PTX.

The effect of diazepam on myocardial function and coronary vascular tone after endotoxemia in the isolated rat heart model

OBJECTIVE AND DESIGN

Tumor necrosis factor alpha (TNF-α) has been implicated in the pathogenesis of cardiovascular disease and sepsis-associated cardiac dysfunction. Although initially described solely as a lipopolysaccharide (LPS)-induced macrophage product, evidence exists that cardiac myocytes themselves produce substantial amounts of TNF-α in response to ischemia as well as LPS. The use of phosphodiesterase inhibitors has been shown to decrease LPS-induced TNF-α elaboration. The aim of the present study was to determine the effect of diazepam (Type IV phosphodiesterase inhibitor) on (1) myocardial function and (2) coronary vascular flow after LPS-induced endotoxic shock in an isolated rat heart model.

MATERIALS AND METHODS

Endotoxemia was induced by intraperitoneal LPS administration in adult male Wistar rats. Hearts were isolated after 6 h and perfused in a working mode with oxygenated Krebs-Henseleit buffer at 37°C. Diazepam was mixed with Krebs-Henseleit buffer and administered (3.0 μg/ml) for 20 min.

RESULTS

LPS-treated hearts showed depressed cardiac function and reduced coronary flow. Myocardial functional parameters (LVDP, +dP/dt, -dP/dt, RPP) and coronary flow (ml/min) were significantly (p < 0.01) improved by diazepam administration.

CONCLUSIONS

These findings suggest that diazepam can salvage myocardial function and undo coronary vascular constriction in the endotoxemic rat heart. These findings are clinically relevant to the treatment of cardiovascular depression caused by endotoxic shock.

Pentoxifylline in ischemia-induced acute kidney injury in rats

Ischemia is an important cause of acute kidney injury (AKI). Pentoxifylline has been shown to improve tissue oxygenation and endothelial function and inhibit proinflammatory cytokine production. The aim of this study was to evaluate a possible renal protective effect of pentoxifylline against ischemia by measuring mitochondrial respiratory metabolism as an index of cell damage. Rats were submitted to right nephrectomy. The left kidney was submitted to ischemia by clamping the renal artery for 45 minutes. Immediately after release of the clamp, 1 mL of a solution containing 20 mg of pentoxifylline/mL was injected intravenously, while a control group received 1 mL of normal saline intravenously. Five minutes after the injection, the left kidney was removed, homogenized, and subjected to refrigerated differential centrifugation. Mitochondrial respiratory metabolism was measured polarographically. The mitochondria isolated from the kidneys of saline-treated rats had an endogenous respiration of 9.20 +/- 1.0 etamol O(2)/mg protein/min compared to 8.9 +/- 1.4 etamol O(2)/mg protein/min in the pentoxifylline-treated rats (p > 0.05). When stimulated by sodium succinate, the respiratory metabolism increased in a similar fashion in both groups of animals: 17.9 +/- 2.3 and 18.1 +/- 2.1 etamol O(2)/mg protein/min in the untreated and pentoxifylline-treated groups, respectively (p > 0.05). In the present study, pentoxifylline was not found to exert any protective effect on the kidney. It is possible that at the time of pentoxifylline administration, the mitochondria had already been damaged by the process of ischemia, and its effect may have been insufficient to reverse cell damage.

[Anti-inflammatory effects of pentoxifylline: importance in cardiac surgery]

Initially introduced as a rheologic agent for use in intermittent claudication due to peripheral artery disease and in ischemic cerebrovascular disease, the methylxanthine derivative pentoxifylline (PTX) has been shown to possess several anti-inflammatory properties which make this drug an interesting immunomodulating adjunct for the management of patients undergoing cardiac surgery. As an unspecific phosphodiesterase inhibitor PTX ameliorates the inflammatory response following a septic stimulus and blunts organ dysfunction after ischemia-reperfusion injury. Apart from this several small clinical studies have shown that the use of PTX may blunt the inflammatory response induced by cardiac surgery using a cardiopulmonary bypass. Additionally it has been shown that the perioperative application of this drug may improve postoperative function of organs at risk, such as the kidneys and liver.

Ghrelin protects mice against endotoxemia-induced acute kidney injury

Acute kidney injury (AKI) in septic patients drastically increases the mortality to 50-80%. Sepsis is characterized by hemodynamic perturbations as well as overwhelming induction of proinflammatory cytokines. Since ghrelin has been shown to have anti-inflammatory properties, we hypothesized that ghrelin may afford renal protection during endotoxemia-induced AKI. Studies were conducted in a normotensive endotoxemia-induced AKI model in mice by intraperitoneal injection of 3.5 mg/kg LPS. Serum ghrelin levels were increased during endotoxemia accompanied by increased ghrelin receptor (GHSR-1a) protein expression in the kidney. Ghrelin administration (1.0 mg/kg sc 6 h and 30 min before and 14 h after LPS) significantly decreased serum cytokine levels (TNF-alpha, IL-1beta, and IL-6) and serum endothelin-1 levels which had been induced by LPS. The elevated serum nitric oxide (NO) levels and renal inducible NO synthase expression were also decreased by ghrelin. Renal TNF-alpha levels were also increased significantly in response to LPS and ghrelin significantly attenuated this increase. When administrated before LPS, ghrelin protected against the fall in glomerular filtration rate at 16 h (172.9 +/- 14.7 vs. 90.6 +/- 15.2 microl/min, P < 0.001) and 24 h (147.2 +/- 20.3 vs. 59.4 +/- 20.7 microl/min, P < 0.05) as well as renal blood flow at 16 h (1.65 +/- 0.07 vs. 1.47 +/- 0.04 ml/min, P < 0.01) and 24 h (1.56 +/- 0.08 vs. 1.22 +/- 0.03 ml/min, P < 0.05) after LPS administration without affecting mean arterial pressure. Ghrelin remained renal protective even when it was given after LPS. In summary, ghrelin offered significant protection against endotoxemia-induced AKI. The renal protective effect of ghrelin was associated with an inhibition of the proinflammatory cytokines. Of particular importance was the suppression of TNF-alpha both in the circulation and kidney tissues. Thus, ghrelin may be a promising peptide in managing endotoxemia-induced AKI.

Role of NF-kappaB and PI 3-kinase/Akt in TNF-alpha-induced cytotoxicity in microvascular endothelial cells

The interaction of tumor necrosis factor (TNF)-alpha with the endothelium is a pivotal factor during endotoxemia. Inflammatory conditions are characterized by the activation of the transcription factor NF-kappaB and the expression of inflammatory mediators. Previous reports indicate that inhibition of NF-kappaB activation during sepsis may be beneficial to the microvasculature. In addition, the phosphatidylinositol-3-kinase/Akt signaling pathway (PI3-kinase/Akt) has been shown to be cytoprotective. In this study, we examined the effect of inhibition of NF-kappaB and PI3-kinase/Akt on cell viability, cytokine production, inducible nitric oxide synthase (iNOS) expression, and nitric oxide (NO) generation by TNF-alpha-treated cultured microvascular endothelial cells. TNF-alpha induced significant cytotoxicity and was associated with increased inflammatory cytokines and NO and increased expression of iNOS. The NF-kappaB inhibitor, pyrrolidine dithiocarbamate (PDTC), prevented these increases and significantly attenuated the TNF-alpha-induced cytotoxicity. TNF-alpha also caused PI3-kinase/Akt activation, which was further increased by PDTC and prevented by the PI3-kinase inhibitor, LY294002. Inhibition of PI3-kinase/Akt also significantly potentiated TNF-alpha-mediated cytotoxicity. LY294002 treatment resulted in the appearance of increased apoptosis, compatible with the known anti-apoptotic properties of PI3-kinase/Akt. The present results therefore demonstrate a cytotoxic effect of TNF-alpha in microvascular endothelial cells which can be attenuated by NF-kappaB inhibition. In addition, PI3-kinase/Akt activation during TNF-alpha exposure may represent a compensatory anti-necrotic and anti-apoptotic pathway. The cytoprotective effects of NF-kappaB inhibition and PI3-kinase/Akt activation may have potential implications in the treatment of endotoxemia and septic shock.

Endotoxemia-related acute kidney injury in transgenic mice with endothelial overexpression of GTP cyclohydrolase-1

Endotoxin-related acute kidney injury has been shown to profoundly induce nitric oxide (NO), which activates sympathetic and renin-angiotensin system, resulting in renal vasoconstriction. While vascular muscle cells are known to upregulate inducible NO synthase (iNOS), less is known about the endothelium as a source of NO during endotoxemia. Studies were, therefore, undertaken both in vitro in mouse microvascular endothelial cells and in vivo in transgenic mice with overexpression of endothelial GTP cyclohydrolase, the rate-limiting enzyme for tetrahydrobiopterin, a cofactor for NO synthase. LPS significantly induced endothelial cell iNOS expression and NO concentration in the culture media, with no change in endothelial NO synthase expression. GTP cyclohydrolase-1 transgenic (Tg) mice demonstrated a significant increase in baseline urine NO-to-creatinine ratio and a more significant increase in renal iNOS expression and serum NO levels with LPS treatment compared with the wild-type (WT) mice. Glomerular filtration rate and renal blood flow decreased significantly in Tg mice with 1.0 mg/kg LPS, while no changes were observed in WT with the same dose of LPS. Serum IL-6 levels were significantly higher in Tg compared with WT mice during endotoxemia. The antioxidant tempol improved the glomerular filtration rate in the Tg mice. Thus endothelium can be an important source of iNOS and serum NO concentration during endotoxemia, thereby increasing the sensitivity to AKI. Reactive oxygen species appear to be involved in this acute renal injury in Tg mice during endotoxemia.

Role of sex steroids in modulating tumor necrosis factor alpha-induced changes in vascular function and blood pressure

BACKGROUND

We previously showed that the infusion of tumor necrosis factor alpha (TNF-alpha) induces hypertension and vascular dysfunction in late pregnant but not virgin rats. In the present study, we tested the hypothesis that levels of ovarian hormones to mimic pregnancy are required for TNF-alpha-induced changes in vascular function and blood pressure in rats.

METHODS

Twenty-one-day-release pellets containing 17beta-estradiol, progesterone, or both were implanted in ovariectomized (OVX) rats. Sham OVX rats were used as controls. Twelve days after implantation, TNF-alpha or vehicle was infused via osmotic minipumps (days 12 to 17). On day 18, mean arterial pressure was measured, and animals were sacrificed to assess vascular function.

RESULTS

Average estrogen and progesterone levels across all groups were 106 +/- 6 pg/mL and 88 +/- 5 ng/mL, respectively. The level of TNF-alpha was 41 +/- 7 pg/mL compared with OVX rats infused with vehicle (4 +/- 1 pg/mL). The results show that TNF-alpha did not cause elevated mean arterial pressure in OVX rats with increased estrogen, progesterone, or both. Vascular responses to the endothelium-dependent and independent agonists, acetylcholine and sodium nitroprusside, were also unchanged. Phenylephrine-induced contraction was moderately but significantly increased at the highest concentrations (10(-4) M) only in TNF-alpha-infused rats.

CONCLUSIONS

These data suggest that increased ovarian hormones to the levels observed during pregnancy are not sufficient to promote TNF-alpha-induced increases in blood pressure or vascular dysfunction.

Proinflammatory cytokines cause down-regulation of renal chloride entry pathways during sepsis

OBJECTIVE

Sepsis is the most important trigger for acute renal failure, with tubular dysfunction and collapse in urine concentration. As chloride plays a major role in the urinary concentrating mechanisms, we aimed to investigate the regulation of renal chloride entry pathways, such as kidney-specific chloride channel 1, kidney-specific chloride channel 2, Barttin, thiazide-sensitive Na+-Cl- cotransporter, renal outer medullary potassium channel, and Na+/K+-adenosine triphosphatase during sepsis.

DESIGN

Prospective animal trial.

SETTING

Laboratory of the Department of Anesthesiology.

SUBJECTS

Male C57/BL6 and B6129SF2/J mice and mice deficient for tumor necrosis factor-alpha, interleukin-1-receptor-1, interferon-gamma, or interleukin-6.

INTERVENTIONS

Mice were injected with lipopolysaccharide (LPS) or proinflammatory cytokines. Hemodynamic and renal variables, cytokine concentrations, and expression of renal chloride-reabsorbing systems were investigated. Experiments with cytokine knockout mice, renal artery-clipped mice, and mice treated with glucocorticoids, low-dose LPS, and sodium nitroprusside were performed.

MEASUREMENTS AND MAIN RESULTS

LPS-injected mice presented with decreased blood pressure and glomerular filtration rate, increased fractional chloride excretion, and depressed expression of renal chloride transporters/channels. Similar alterations were observed after application of tumor necrosis factor-alpha, interleukin-1beta, interferon-gamma, or interleukin-6. LPS-induced down-regulation of chloride transporters/channels was not affected in cytokine knockout mice. Glucocorticoid treatment inhibited LPS-induced increase of cytokine concentrations, diminished LPS-induced renal dysfunction, and attenuated the down-regulation of renal chloride transporters/channels. Injection of low-dose LPS increased renal tissue cytokines and down-regulated chloride entry pathways without arterial hypotension, indicating that renal ischemia due to systemic hypotension does not mediate down-regulation of renal chloride transporters/channels. In addition, renal ischemia induced by renal artery clipping or sodium nitroprusside administration did not influence chloride transporter/channel expression.

CONCLUSIONS

Our results demonstrate down-regulation of renal chloride transporters/channels during sepsis, which is probably mediated by proinflammatory cytokines and accounts for the development of LPS-induced tubular dysfunction. Our findings contribute to the understanding, on one hand, the failure of single-anticytokine strategies and, on the other hand, the beneficial effects of glucocorticoids in the therapy of septic patients.

Functions of TNF and its receptors in renal disease: distinct roles in inflammatory tissue injury and immune regulation

Tumor necrosis factor (TNF) alpha is a potent proinflammatory cytokine and important mediator of inflammatory tissue damage. In addition, it has important immune-regulatory functions. Many experimental studies and clinical observations support a role for TNF in the pathogenesis of acute and chronic renal disease. However, given its dual functions in inflammation and immune regulation, TNF may mediate both proinflammatory as well as immunosuppressive effects, particularly in chronic kidney diseases and systemic autoimmunity. Blockade of TNF in human rheumatoid arthritis or Crohn's disease led to the development of autoantibodies, lupus-like syndrome, and glomerulonephritis in some patients. These data raise concern about using TNF-blocking therapies in renal disease because the kidney may be especially vulnerable to the manifestation of autoimmune processes. Interestingly, recent experimental evidence suggests distinct roles for the 2 TNF receptors in mediating local inflammatory injury in the kidney and systemic immune-regulatory functions. In this review the biologic properties of TNF and its receptors, TNF receptors 1 and 2, relevant to kidney disease are summarized followed by a review of the available experimental and clinical data on the pathogenic role of the TNF system in nonimmune and immune renal diseases. Experimental evidence also is reviewed that supports a rationale for specifically blocking TNF receptor 2 versus anti-TNF therapies in some nephropathies, including immune complex-mediated glomerulonephritis.

Prostacyclin in endotoxemia-induced acute kidney injury: cyclooxygenase inhibition and renal prostacyclin synthase transgenic mice

Sepsis-related acute kidney injury (AKI) is the leading cause of AKI in intensive care units. Endotoxin is a primary initiator of inflammatory and hemodynamic consequences of sepsis and is associated with experimental AKI. The present study was undertaken to further examine the role of the endothelium, specifically prostacyclin (PGI(2)), in the pathogenesis of endotoxemia-related AKI. A low dose of endotoxin (LPS, 1 mg/kg) in wild-type (WT) mice was associated with stable glomerular filtration rate (GFR) (164.0 +/- 16.7 vs. 173.3 +/- 6.7 microl/min, P = not significant) as urinary excretion of 6-keto-PGF(1alpha), the major metabolite of PGI(2), increased. When cyclooxygenase inhibition with indomethacin abolished this rise in 6-keto-PGF(1alpha), the same low dose of LPS significantly decreased GFR (110.7 +/- 12.1 vs. 173.3 +/- 6.7 microl/min, P < 0.05). The same dose of indomethacin did not alter GFR in WT mice. To further study the role of PGI(2) in endotoxemia, renal-specific PGI synthase (PGIs) transgenic (Tg) mice were developed that had increased PGIs expression only in the kidney and increased urinary 6-keto-PGF(1alpha). These Tg mice, however, demonstrated endotoxemia-related AKI with low-dose LPS (1 mg/kg) (GFR: 12.6 +/- 3.9 vs. 196.5 +/- 21.0 microl/min P < 0.01), which did not alter GFR in WT mice (164.0 +/- 16.7 vs. 173.3 +/- 6.7 microl/min, P = not significant). An elevation in renal cAMP, however, suggested an activation of the PGI(2)-cAMP-renin system in these Tg mice. Moreover, angiotensin-converting enzyme inhibition afforded protection against endotoxin-related AKI in these Tg mice. Thus endothelial PGIs-mediated PGI(2), as previously shown with endothelial nitric oxide synthase-mediated nitric oxide, contributes to renal protection against endotoxemia-related AKI. This effect may be overridden by excessive activation of the renin-angiotensin system in renal-specific PGIs Tg mice.

Endotoxin and cisplatin synergistically induce renal dysfunction and cytokine production in mice

A major toxicity of the cancer chemotherapeutic agent cisplatin is acute renal failure. Sepsis is a common cause of acute renal failure in humans and patients who receive cisplatin are at increased risk for sepsis. Accordingly, this study examined the interactions between cisplatin and endotoxin in vivo with respect to renal function and cytokine production. Mice were treated with either a single dose of cisplatin or two doses of LPS administered 24 h apart, or both agents in combination. Administration of 10 mg/kg cisplatin had no effect on blood urea nitrogen or creatinine levels throughout the course of the study. LPS resulted in a modest rise in blood urea nitrogen at 24 and 48 h, which returned to normal by 72 h. In contrast, mice treated with both cisplatin and LPS developed severe renal failure and an increase in mortality. Urine, but not serum, TNF-alpha levels showed a synergistic increase by cisplatin and LPS. Urinary IL-6, MCP-1, KC, and GM-CSF also showed a synergistic increase with cisplatin+LPS treatment. The renal dysfunction induced by cisplatin+LPS was completely dependent on TLR4 signaling and partially dependent on TNF-alpha production. Increased cytokine production was associated with a moderate increase in infiltrating leukocytes which was not different between cisplatin+LPS and LPS alone. These results indicate that cisplatin and LPS act synergistically to produce nephrotoxicity which may involve proinflammatory cytokine production.

Regulation of renal sodium transporters during severe inflammation

Sepsis-associated acute renal failure is characterized by decreased GFR and tubular dysfunction. The pathogenesis of endotoxemic tubular dysfunction with failure in urine concentration and increased fractional sodium excretion is poorly understood. This study investigated the regulation of renal sodium transporters during severe inflammation in vivo and in vitro. Injection of high-dosage LPS reduced BP and GFR, increased fractional sodium excretion, and strongly decreased the expression of Na(+)/H(+)-exchanger, renal outer medullary potassium channel, Na(+)-K(+)-2Cl(-) co-transporter, epithelial sodium channel, and Na(+)/K(+)-ATPase in mice. Also, injection of TNF-alpha, IL-1beta, or IFN-gamma decreased renal function and expression of renal sodium transporters. LPS-induced downregulation of sodium transporters was not affected in cytokine-knockout mice. However, supplementary glucocorticoid treatment, which inhibited LPS-induced increase of tissue cytokine concentrations, attenuated LPS-induced renal dysfunction and downregulation of tubular sodium transporters. Injection of low-dosage LPS increased renal tissue cytokines and downregulated renal sodium transporters without arterial hypotension. In vitro, in cortical collecting duct cells, cytokines also decreased expression of renal outer medullary potassium channel, epithelial sodium channel, and Na(+)/K(+)-ATPase. Renal hypoperfusion by renal artery clipping did not influence renal sodium transporter expression, in contrast to renal ischemia-reperfusion injury, which depressed transporter expression. These findings demonstrate downregulation of renal sodium transporters that likely accounts for tubular dysfunction during inflammation. These data suggest that alteration of renal sodium transporters during LPS-induced acute renal failure is mediated by cytokines rather than renal ischemia. However, in a complex in vivo model of severe inflammation, the possible presence and influence of renal hypoperfusion and reperfusion on the expression of renal sodium transporters cannot be completely excluded.