Lazaroid and pentoxifylline suppress sepsis-induced increases in renal vascular resistance via altered arachidonic acid metabolism

Alamandine treatment prevents LPS-induced acute renal and systemic dysfunction with multi-organ injury in rats via inhibiting iNOS expression

Sepsis is defined as the dysregulated immune response leading to multi-organ dysfunction and injury. Sepsis-induced acute kidney injury is a significant contributor to morbidity and mortality. Alamandine (ALA) is a novel endogenous peptide of the renin-angiotensin-aldosterone system. It is known for its anti-inflammatory and anti-apoptotic effects, but its functional and vascular effects on sepsis remain unclear. We aimed to investigate the effects of ALA, as a pre- and post-treatment agent, on lipopolysaccharide (LPS)-induced systemic and renal dysfunction and injury in the LPS-induced endotoxemia model in rats via functional, hemodynamic, vascular, molecular, biochemical, and histopathological evaluation. 10 mg/kg intraperitoneal LPS injection caused both hepatic and renal injury, decreased blood flow in several organs, and renal dysfunction at 20 h in Sprague-Dawley rats. Our results showed that ALA treatment ameliorated systemic and renal inflammation, reduced inflammatory cytokines, prevented the enhancement of the mortality rate, reversed vascular dysfunction, corrected decreased blood flows in several organs, and reduced renal and hepatic injury via inhibiting iNOS (inducible nitric oxide synthase) and caspase expressions in the kidney. In addition, expressions of different ALA-related receptors showed alterations in this model, and ALA treatment reversed these alterations. These data suggest that ALA's systemic and renal protective effects are achieved through its anti-inflammatory, anti-pyroptotic, and anti-apoptotic effects on hemodynamic and vascular functions via reduced iNOS expression.

Therapeutic regimens of endotoxaemia in sheep

Endotoxaemia is an inflammatory condition which happens due to the presence of outer cell wall layer of Gram-negative bacteria in blood circulation, containing lipopolysaccharide commonly known as endotoxin. This condition causes high mortality in affected animals and sheep are highly susceptible in this regard. Several researchers have emphasised the therapeutic regimens of endotoxaemia and its sequels in sheep. Furthermore, sheep are among the most commonly used animal species in experimental studies on endotoxaemia, and for the past five decades, ovine models have been employed to evaluate different aspects of endotoxaemia. Currently, there are several studies on experimentally induced endotoxaemia in sheep, and information regarding novel therapeutic protocols in this species contributes to better understanding and treating the condition. This review aims to specifically introduce various treatment methods of endotoxaemia in sheep.

Determination of Melatonin Deprivation Impact on Sepsis With Acute Phase Reactants

BACKGROUND

The aim of the present study is to determine the association of melatonin hormone level on CRP, Total Antioxidant Status, Leukocyte, Procalcitonin, and Malondialdehyde, all acute phase reactants in the dark and light cycle of rats with sepsis model.

MATERIALS AND METHODS

In this study, 54 rats were divided into three groups. Whereas the first and third groups had a 12 h dark-light cycle, the second group was exposed to light for 24 h at 21°C-22°C for 10 d without any water and food restrictions. In the second and third groups, sepsis model was formed by cecal ligation and puncture (CLP) method at the end of 10th day, and blood samples were taken at the end of the 10th day. C-reactive protein, Malondialdehyde, Procalcitonin in the blood samples were analyzed by ELISA, and the levels of Total Antioxidant Status and leukocyte were determined by colorimetric method in the subsequent 12 and 24 h.

RESULTS

CRP values increased in the second group rats, which were kept continuously under light and had undergone CLP, from 288.8 mg/L to 584.0 mg/L at the end of the 12 h and the end of the 24 h, approximately, two times. In rats, which were kept under 12 h of light, 12 h of darkness, and applied CLP (group 3), these values increased from 416.9 to 619.1; an increase of 1.5 times. When assessed for MDA, it was determined that the differences between Group 2 and Group 3 were more prominent between 0 h and 12 h. While the MDA values in group 2 increased from 16.53 nmol/mL at the 12 h to 17.66 nmol/mL at the 24 h. However, MDA values did not yield statistically significant changes in the third group. Changes in the in PCT values were similar to the MDA values obtained. Increase coefficient of the PCT values between 0 h and 12 h in the second group 2 was 1.26; however, in the third group, it was negligible.

CONCLUSIONS

An increase in the oxidative stress was observed in the rats that underwent CLP and melatonin deprivation via continuous 24 h light exposure for 10 d. Accordingly, deprivation of light is considered to be effective in sepsis treatment due to the increase in melatonin levels in intensive care unit patients.

Effect of pentoxifylline on renal function and urinary albumin excretion in patients with diabetic kidney disease: the PREDIAN trial

Diabetic kidney disease (DKD) is the leading cause of ESRD. We conducted an open-label, prospective, randomized trial to determine whether pentoxifylline (PTF), which reduces albuminuria, in addition to renin-angiotensin system (RAS) blockade, can slow progression of renal disease in patients with type 2 diabetes and stages 3-4 CKD. Participants were assigned to receive PTF (1200 mg/d) (n=82) or to a control group (n=87) for 2 years. All patients received similar doses of RAS inhibitors. At study end, eGFR had decreased by a mean±SEM of 2.1±0.4 ml/min per 1.73 m(2) in the PTF group compared with 6.5±0.4 ml/min per 1.73 m(2) in the control group, with a between-group difference of 4.3 ml/min per 1.73 m(2) (95% confidence interval [95% CI], 3.1 to 5.5 ml/min per 1.73 m(2); P<0.001) in favor of PTF. The proportion of patients with a rate of eGFR decline greater than the median rate of decline (0.16 ml/min per 1.73 m(2) per month) was lower in the PTF group than in the control group (33.3% versus 68.2%; P<0.001). Percentage change in urinary albumin excretion was 5.7% (95% CI, -0.3% to 11.1%) in the control group and -14.9% (95% CI, -20.4% to -9.4%) in the PTF group (P=0.001). Urine TNF-α decreased from a median 16 ng/g (interquartile range, 11-20.1 ng/g) to 14.3 ng/g (interquartile range, 9.2-18.4 ng/g) in the PTF group (P<0.01), with no changes in the control group. In this population, addition of PTF to RAS inhibitors resulted in a smaller decrease in eGFR and a greater reduction of residual albuminuria.

Propofol increases bone morphogenetic protein-7 and decreases oxidative stress in sepsis-induced acute kidney injury

BACKGROUND

Pro-inflammatory cytokines and free radicals damage renal tissue leading to acute kidney injury (AKI) during sepsis. Bone morphogenetic protein-7 (BMP-7) represses tumour necrosis factor (TNF)-α-induced inflammatory responses and protects kidney from injury. The sedative agent, propofol, has immunomodulatory and antioxidative properties. The present study investigated whether propofol could reduce AKI in caecal ligation and puncture (CLP) mice and the possible mechanism behind this.

METHODS

Mice were treated with propofol or saline immediately and 12 h after CLP surgery. Kidney injury, survival and cytokine expressions of CLP mice were observed 24 h after CLP surgery. In vitro, lipopolysaccharide (LPS)-stimulated rat mesangial cells (RMCs) or hydrogen peroxide (H(2)O(2))-exposed murine kidney epithelial cells (M1) were treated with propofol. The expression of BMP-7, TNF-α and monocyte chemotactic protein (MCP)-1 in CLP mice kidney, RMCs or M1 cells was determined by RT-PCR. Free radical generation and cell death of RMCs and M1 cells were analysed. Nuclear factor (NF)-κB and peroxisome proliferator-activated receptor (PPAR)-γ expressions in LPS-stimulated RMCs were determined by western blotting.

RESULTS

Propofol increased survival and ameliorated AKI in CLP mice. Propofol increased BMP-7 expression but decreased TNF-α and MCP-1 expressions in the kidney of CLP mice and LPS-stimulated RMCs. Propofol also inhibited free radical generation and cell death in LPS-stimulated RMCs and decreased the TNF-α expression and cell death in H(2)O(2)-exposed M1 cells. Moreover, propofol decreased NF-κB but increased PPAR-γ expression in LPS-stimulated RMCs.

CONCLUSIONS

Propofol treatment could protect kidney from sepsis-induced AKI by increasing BMP-7 expression, decreasing inflammatory cytokines and inhibiting oxidative stress.

Mechanisms, detection, and potential management of microcirculatory disturbances in sepsis

Despite improvements in resuscitation and treatment of sepsis, the morbidity and mortality remain unacceptably high. Microvascular dysfunction has been shown to play a significant role in the pathogenesis of sepsis and is a potential new target in the management of sepsis. Clinical studies, aided by new techniques that allow for real-time assessment of the microcirculation, have shown that disturbances in microcirculatory flow are common in sepsis and correlate with worse outcomes. Bedside measurement of microcirculatory perfusion has become simpler and more accessible, and may provide key insights into prognosis in sepsis and guide future therapeutics, much like mean arterial pressure (MAP), lactate, and mixed central oxygen saturation (SvO(2)) do now. The authors review here the role of microcirculatory dysfunction in sepsis and its potential role as a therapeutic target in sepsis.

ACE inhibition restores the vasodilator potency of the endothelium-derived relaxing factor, L-S-nitrosocysteine, in conscious Spontaneously Hypertensive rats

OBJECTIVE

The major aim of this study was to determine whether the angiotensin converting enzyme (ACE) inhibitors, captopril or enalapril, restore the diminished vasodilator potency of the endothelium-dependent agonist, acetylcholine (ACh), and the endothelium-derived relaxing factor (EDRF), L-S-nitrosocysteine (L-SNC), in conscious Spontaneously Hypertensive (SH) rats.

METHODS

The hemodynamic responses elicited by i.v. injections of ACh, L-SNC, and nitric oxide donors such as MAHMA NONOate, were determined in SH rats treated for 7 days with captopril, enalapril, or the direct vasodilator hydralazine. The effects of captopril, enalapril or hydralazine on oxidant stress levels in blood serum and aorta of WKY and SH rats were also determined.

RESULTS

Captopril, enalapril and hydralazine elicited equivalent falls in mean arterial pressure and systemic vascular resistances in SH rats. ACh- and L-SNC-induced vasodilation were increased in captopril- or enalapril-treated SH rats such that the responses were equal to those in normotensive Wistar Kyoto rats. The attenuated responses of ACh and L-SNC in SH rats were not improved by hydralazine. The vasodilator effects of MAHMA NONOate, which were substantially augmented in SH rats, were not affected by captopril, enalapril or hydralazine. The levels of oxidant stress were markedly reduced in captopril- or enalapril-treated but not hydralazine-treated SH rats.

CONCLUSIONS

The finding that the ACE inhibitors improved the vasodilator potencies of L-SNC and the EDRF released by ACh in SH rats, suggests that the diminished vasodilator potency of these compounds was due to augmented ACE activity, which increased oxidant stress levels. This study provides the first evidence to support the concept that ACE inhibition lowers arterial pressure in SH rats, at least in part, by restoring the vasodilator potency of endothelium-derived L-SNC.

Renal failure secondary to acute tubular necrosis: epidemiology, diagnosis, and management

Acute tubular necrosis (ATN) is a form of acute renal failure (ARF) that is common in hospitalized patients. In critical care units, it accounts for about 76% of cases of ARF. Despite the introduction of hemodialysis > 30 years ago, the mortality rates from ATN in hospitalized and ICU patients are about 37.1% and 78.6%, respectively. The purpose of this review is to discuss briefly the cause, diagnosis, and epidemiology of ARF, and to review in depth the clinical trials performed to date that have examined the influence of growth factors, hormones, antioxidants, diuretics, and dialysis. In particular, the role of the dialysis modality, dialyzer characteristics, and dosing strategies are discussed.

Cyclo-oxygenase-2, endothelium and aortic reactivity during deoxycorticosterone acetate salt-induced hypertension

OBJECTIVE

To test the hypothesis that the enhanced vascular responsiveness to norepinephrine that occurs during deoxycorticosterone acetate (DOCA)-salt induced hypertension is causally related to increased expression of cyclo-oxygenase (COX)-2 and oxidative stress, which diminishes the vasomodulatory influence of endothelium-derived nitric oxide.

METHODS

Four groups of age-matched, male Sprague-Dawley rats were studied: Sham (normotensive); DOCA-salt (hypertensive); DOCA-salt treated with manganese(III) tetra(4-benzoic acid) porphyrin chloride [MnTBAP, an antioxidant; 15 mg/kg intraperitoneally (i.p.) for 21 days]; DOCA-salt treated with {N-[2-(cyclohexyloxy)-4-nitrophenyl]-methane sulfonamide} (NS-398, a COX-2 selective blocker; 5 mg/kg i.p. for 7 days). Contraction and relaxation were measured with FT03 force transducers coupled to a Grass polygraph in aortic rings bathed with physiologic salt solution (37 degrees C) and bubbled with a 5%CO2/95%O2 gas mixture. Aortic sensitivities (pD2 values) to norepinephrine and serum isoprostanes (8-iso-prostaglandin F2alpha, a marker of oxidative stress) were measured for each experimental paradigm.

RESULTS

NS-398 significantly reduced maximal contractions in response to norepinephrine in aortic rings from Sham (44 +/- 3%) and DOCA-salt (96 +/- 2%) group rats. Expression of COX-2 protein increased significantly in vessels from DOCA-salt rats compared with those from Sham group rats. Treatment of DOCA-salt rats with either MnTBAP or NS-398 alleviated hypertension, normalized aortic pD2 values for norepinephrine and restored serum 8-isoprostane concentrations towards those observed in Sham group rats.

CONCLUSIONS

COX-2 expression increases during DOCA-salt hypertension, and mediates production of factors that enhance rat aortic contractility in response to norepinephrine. Our data also suggest a role for increased oxidative stress, which is at least in part dependent on enhanced COX-2 expression, in the mechanism(s) of enhanced aortic contractility in response to norepinephrine during DOCA-salt hypertension.

Immune cells: free radicals and antioxidants in sepsis

The excessive production of reactive oxygen species (ROS), associated with inflammation, leads to a condition of oxidative stress. Oxidative stress is a major contributing factor to the high mortality rates associated with several diseases such as endotoxic shock. This condition can be controlled to a certain degree by antioxidant therapies. Immune cells use ROS in order to support their functions and therefore need adequate levels of antioxidant defenses in order to avoid the harmful effect of an excessive production of ROS. This review discusses the toxic effects of endotoxin, paying particular attention to immune function. It continues by analyzing the mechanism to which specific cells of the immune system recognize endotoxin, and the resulting pathways leading to nuclear factor-kappaB activation and proinflammatory gene transcription. We also focus on the involvement of reactive oxygen and nitric oxide (NO) and the protective role of antioxidants. The potential clinical use of antioxidants in the treatment of sepsis and the effects on the redox state of the immune cells are discussed.

Pentoxifylline reduces acute lung injury in chronic endotoxemia

BACKGROUND

Pentoxifylline (PTX) attenuates end-organ injury in models of sepsis and hemorrhage. PTX is thought to act by inhibiting phosphodiesterase, thus increasing cAMP and decreasing tumor necrosis factor-alpha (TNF-alpha) synthesis. The effects of PTX on neutrophil and endothelial cell adhesion molecules and, ultimately, organ injury in a chronic endotoxemia model have not been studied. We hypothesized that continuous infusion of PTX reduces acute lung injury (ALI) caused by chronic lipopolysaccharide (LPS) exposure.

MATERIALS AND METHODS

Male Sprague-Dawley rats were given continuous infusion of LPS, PTX + LPS combined, or saline (sham) by implantable pumps. Neutrophil CD11b expression, lung histopathology, lung intercellular adhesion molecule-1 (ICAM-1) expression assessed by immune staining, serum TNF-alpha, serum interleukin-6 (IL-6), and bronchoalveolar lavage (BAL) IL-8 were evaluated at different time points. Lung injury was graded in a blinded fashion from 0 (normal) to 4 (severe) for interstitial inflammation, neutrophil infiltration, congestion, and edema. Total lung injury score (TLIS) was calculated by adding listed categories. White cell count in the peripheral blood and in the BAL was also performed.

RESULTS

Animals treated with PTX + LPS showed a significant reduction in lung injury score, a marked decrease in ICAM-1 expression, and a significant decrease in IL-8 levels in the BAL and serum IL-6 levels when compared with LPS-treated animals.

CONCLUSIONS

Continuous infusion of PTX reduces ALI caused by chronic endotoxemia. The effect seems to be a result of decreased expression of endothelial and epithelial ICAM-1 and modulation of proinflammatory cytokine synthesis.

Tempol, an antioxidant, restores endothelium-derived hyperpolarizing factor-mediated vasodilation during hypertension

Acetylcholine releases a non-prostanoid endothelium-derived hyperpolarizing factor (EDHF) and nitric oxide from physiological salt solution perfused rat mesenteric arteries. This study reports an impairment in EDHF-mediated vasodilation in deoxycorticosterone acetate (DOCA)-salt hypertensive versus control normotensive rats. Nitric oxide-mediated vasodilation to acetylcholine was not altered in the animals. We hypothesize that free radical species generated as by-products of arachidonic acid metabolism contribute to impaired EDHF-mediated dilation in DOCA-salt hypertension. With or without reduced nicotinamide adenine dinucleotide phosphate (NADPH) as co-factor, arterial microsomes generate free radical species upon incubation with arachidonic acid. The production of free radicals was significantly higher in DOCA-salt versus control rat microsomes, and was totally eliminated by addition of cyclooxygenase-2 inhibitors NS-398 or celecoxib at 30 microM. Treatment of DOCA-salt rats with tempol (an antioxidant; 15 mg/kg, i.p., 21 days) alleviates hypertension; improves acetylcholine-induced EDHF-mediated vasodilation in DOCA-salt rats, and decreases arachidonic acid-driven microsomal free radical production. Serum level of 8-isoprostanes is elevated in DOCA-salt hypertension versus control or sham-salt rats, and the increase was reversed by tempol treatment. These results show that EDHF-mediated dilation of rat mesenteric arteries is impaired in DOCA-salt induced hypertension. Our data also suggest that cyclooxygenase-2 mediates free radical production, and that free radicals modulate the EDHF-mediated vascular response in DOCA-salt induced hypertension.

Oxidative stress and gene expression in sepsis

Dysregulation of the immuno-inflammatory response, as seen in sepsis, may culminate in host cell and organ damage. Lipopolysaccharide from Gram-negative bacterial cell walls induces gene activation and subsequent inflammatory mediator expression. Gene activation is regulated by a number of transcription factors at the nuclear level, of which nuclear factor kappaB appears to have a central role. The redox (reduction-oxidation) cellular balance is important for normal cellular function, including transcription factor regulation. In sepsis, a state of severe oxidative stress is encountered, with host endogenous antioxidant defences overcome. This has implications for cellular function and the regulation of gene expression. This review gives an overview of the mechanisms by which transcription factor activation and inflammatory mediator overexpression occur in sepsis, together with the events surrounding the state of oxidative stress encountered and the effects on the host's antioxidant defences. The effect of oxidative stress on transcription factor regulation is considered, together with the role of antioxidant repletion in transcription factor activation and in sepsis in general. Other interventions that may modulate transcription factor activation are also highlighted.

Pentoxifylline influences the autocrine function of organ cultured donor corneas and enhances endothelial cell survival

BACKGROUND/AIMS

Scientific interest in pentoxifylline has been reawakened owing to the recognised effects of this drug on immune functions, particularly its influence on cytokine production. In a previous study, the authors demonstrated that spiking of organ culture media with endotoxin elicited a marked enhancement in the release of IL-6 and IL-8 from corneal tissue and that these events coincided with degenerative changes in endothelial cells and a higher incidence of actual loss among this population. Since traces of donor derived endotoxin can be detected in up to 50% of corneal organ cultures, this substance may have a direct influence on graft viability or trigger inflammatory responses in the host. They, therefore, wished to ascertain whether supplementation of media with pentoxifylline improved endothelial cell survival in organ cultured donor corneas.

METHODS

12 fellow pairs of donor corneas were cultured for 20 days, with a change of medium on day 10: One of each pair was incubated in the absence, and the other in the presence, of pentoxifylline (25 microg/ml). Samples of medium were withdrawn at regular intervals during the course of incubation and screened for cytokines IL-6, IL-8, and prostaglandin E2 by ELISA. Endothelial cell morphology and numerical density were assessed on days 0, 10 and 20.

RESULTS

Addition of pentoxifylline to organ culture media led to a significant improvement in endothelial cell survival. This drug also elicited a significant increase in the level of IL-6 and marginally suppressed that of IL-8 during the initial 10 day phase of incubation. During the second 10-20 day phase, the level of both IL-6 and IL-8 decreased significantly in the presence of pentoxifylline, the relation between these two cytokines being the inverse of that observed in the absence of the drug. No significant changes in the level of prostaglandin E2 were apparent.

CONCLUSION

The addition of pentoxifylline to organ culture media leads, ultimately, to a suppression of IL-6 and IL-8 secretion by corneal tissue. The potentially damaging effects of these cytokines are thereby quelled, as evidenced by the improvement in endothelial cell survival.