Heat preconditioning attenuates renal injury in ischemic ARF in rats: role of heat-shock protein 70 on NF-kappaB-mediated inflammation and on tubular cell injury

The Mechanism of Hyperoxia-Induced Neonatal Renal Injury and the Possible Protective Effect of Resveratrol

With recent advances in neonatal intensive care, preterm infants are surviving into adulthood. Nonetheless, epidemiological data on the health status of these preterm infants have begun to reveal a worrying theme; prematurity and the supplemental oxygen therapy these infants receive after birth appear to be risk factors for kidney disease in adulthood, affecting their quality of life. As the incidence of chronic kidney disease and the survival time of preterm infants both increase, the management of the hyperoxia-induced renal disease is becoming increasingly relevant to neonatologists. The mechanism of this increased risk is currently unknown, but prematurity itself and hyperoxia exposure after birth may predispose to disease by altering the normal trajectory of kidney maturation. This article reviews altered renal reactivity due to hyperoxia, the possible mechanisms of renal injury due to hyperoxia, and the role of resveratrol in renal injury. KEY POINTS: · Premature infants commonly receive supplementary oxygen.. · Hyperoxia can cause kidney damage via signal pathways.. · We should reduce the occurrence of late sequelae..

Involvement of heat shock proteins HSP70 in the mechanisms of endogenous neuroprotection: the prospect of using HSP70 modulators

This analytical review summarizes literature data and our own research on HSP70-dependent mechanisms of neuroprotection and discusses potential pharmacological agents that can influence HSP70 expression to improve neurological outcomes and effective therapy. The authors formed a systemic concepts of the role of HSP70-dependent mechanisms of endogenous neuroprotection aimed at stopping the formation of mitochondrial dysfunction, activation of apoptosis, desensitization of estrogen receptors, reduction of oxidative and nitrosative stress, prevention of morpho-functional changes in brain cells during cerebral ischemia, and experimentally substantiated new target links for neuroprotection. Heat shock proteins (HSPs) are an evolutionarily integral part of the functioning of all cells acting as intracellular chaperones that support cell proteostasis under normal and various stress conditions (hyperthermia, hypoxia, oxidative stress, radiation, etc.). The greatest curiosity in conditions of ischemic brain damage is the HSP70 protein, as an important component of the endogenous neuroprotection system, which, first of all, performs the function of intracellular chaperones and ensures the processes of folding, holding and transport of synthesized proteins, as well as their degradation, both under normoxic conditions and stress-induced denaturation. A direct neuroprotective effect of HSP70 has been established, which is realized through the regulation the processes of apoptosis and cell necrosis due to a long-term effect on the synthesis of antioxidant enzymes, chaperone activity, and stabilization of active enzymes. An increase in the level of HSP70 leads to the normalization of the glutathione link of the thiol-disulfide system and an increase in the resistance of cells to ischemia. HSP 70 is able to activate and regulate compensatory ATP synthesis pathways during ischemia. It was found that in response to the cerebral ischemia formation, HIF-1a is expressed, which initiates the launch of compensatory mechanisms for energy production. Subsequently, the regulation of these processes switches to HSP70, which "prolongs" the action of HIF-1a, and also independently maintains the expression of mitochondrial NAD-dependent malate dehydrogenase activity, thereby maintaining the activity of the malate-aspartate shuttle mechanism for a long time. During ischemia of organs and tissues, HSP70 performs a protective function, which is realized through increased synthesis of antioxidant enzymes, stabilization of oxidatively damaged macromolecules, and direct anti-apoptotic and mitoprotective action. Such a role of these proteins in cellular reactions during ischemia raises the question of the development of new neuroprotective agents which are able to provide modulation/protection of the genes encoding the synthesis of HSP 70 and HIF-1a proteins. Numerous studies of recent years have noted the important role of HSP70 in the implementation of the mechanisms of metabolic adaptation, neuroplasticity and neuroprotection of brain cells, so the positive modulation of the HSP70 system is a perspective concept of neuroprotection, which can improve the efficiency of the treatment of ischemic-hypoxic brain damage and be the basis for substantiating of the feasibility of using of HSP70 modulators as promising neuroprotectors.

HSP70 Ameliorates Septic Acute Kidney Injury via Binding with TRAF6 to Inhibit of Inflammation-Mediated Apoptosis

Purpose

Methods

Results

Conclusion

Heat precondition is a potential strategy to combat hepatic injury triggered by severe heat stress

AIM

Environmental heat stress alters physiological and biochemical functions which leads to multiorgan dysfunction including severe hepatic injury in animals. We hypothesize that heat preconditioning can be potential intervention in combating heat illnesses.

MAIN METHODS

Sprague Dawley rats were exposed to moderate heat stress, severe heat stress and heat preconditioning in heat simulation chamber. Mean arterial pressure, heart rate, skin and core temperature were monitored in pre and post heat exposed animals. After stress exposure, blood for hemodynamic and liver tissue for liver function tests, oxidative stress, inflammatory variables and structural studies were collected from rats. Hepatic mitochondria were isolated to study the key structural alterations and functional changes by transmission electron microscopy.

KEY FINDINGS

The effect of heat precondition shows improvement in time to attain the core temperature, weight loss, blood pressure and heart rate in rats. Results exhibited decreased levels of liver function tests, elevated levels of free radicals and inflammatory cytokines in heat exposed liver as compared with heat preconditioned animals. Expression levels of mitochondrial heat shock protein 60, superoxide dismutase 1 and uncoupling protein 1 along with activity of electron transport chain complexes I-V were examined and found to be increased in heat preconditioned as compared to heat stressed animals. Morphological studies of liver parenchyma demonstrated reduction in structural deterioration of hepatic lobules and restoration of mitochondrial structural integrity in heat preconditioned rats.

SIGNIFICANCE

Present study suggests that heat preconditioning intervention plays a crucial role in protection against heat induced hepatic injury in animals.

Melatonin protects against tenofovir-induced nephrotoxicity in rats by targeting multiple cellular pathways

Nephrotoxicity is a dose-limiting side effect of long-term use of tenofovir, a reverse transcriptase inhibitor that is used for the treatment of HIV infection and chronic hepatitis B infection. Identifying an agent that prevents tenofovir disoproxil fumarate (TDF)-induced renal injury can lead to its better tolerance, and a more effective treatment can be achieved. The present study is aimed at investigating whether melatonin, a potent antioxidant and anti-inflammatory agent, protects against TDF nephrotoxicity in rats and to determine its cellular targets. Rats were divided into groups and treated as follows. Group I (control): Rats in this group (n = 6) received sterile water only by gavage for 35 days. Group II: Rats (n = 6) in this group received 600 mg/kg body weight TDF in sterile water by gavage for 35 days. Group III: Rats (n = 6) in this group received once daily 20 mg/kg bodyweight melatonin i.p. 2 h before the administration of 600 mg/kg body weight TDF in sterile water by gavage for 35 days. Group IV: Rats were pretreated daily with 20 mg/kg body weight melatonin i.p. 2 h before the administration of sterile water by gavage. All the rats were sacrificed on the 36th day, after overnight fast. Melatonin pretreatment protected the rats against TDF nephrotoxicity both histologically and biochemically. Biochemically, melatonin pretreatment attenuated TDF-induced, oxidative stress, nitrosative stress, mitochondrial pathway of apoptosis, PARP overactivation and preserved proximal tubular function (p < 0.01). This suggests that melatonin may be useful in ameliorating TDF nephrotoxicity.

Selenium Deficiency Induces Inflammation via the iNOS/NF-κB Pathway in the Brain of Pigs

Selenium (Se) is an essential trace element to maintain homeostasis in humans and animals. The aim of the present study was to clarify the mechanism of Se deficiency-induced inflammation in the pig's brain. Twenty-four healthy pigs were randomly divided into two groups (n = 12/group): control group (group C) was fed diet with 0.3 mg/kg inorganic Se, and Se-deficient group (group L) was fed diet with 0.007 mg/kg inorganic Se. At the 90th day of the experiment, the histology in the pig's brain was observed by the microscope, the NO levels and iNOS activity were assayed, and the mRNA and protein expression levels of inflammatory cytokines (iNOS, COX-2, NF-κB, and PTGEs) and HSPs (HSP27, HSP40, HSP60, HSP70, and HSP90) were detected by real-time quantitative PCR and Western blot. Compared with group C, both of NO levels and iNOS activity were increased in group L, and the mRNA and protein expression levels of inflammatory cytokines (iNOS, COX-2, NF-κB, and PTGEs) and HSPs (HSP27, HSP40, HSP60, HSP70, and HSP90) were also upregulated; histological observation displayed inflammatory response in the brain of pig. In summary, diet with Se deficiency can activate the iNOS/NF-κB pathway to upregulate the expression of inflammatory cytokines, thereby leading to inflammatory lesions in the pig's brain, and HSPs are involved in the compensatory regulation of inflammation. This study provides a reference for the prevention of pig brain inflammation from the perspective of nutrition.

Empty SV40 capsids increase survival of septic rats by eliciting numerous host signaling networks that participate in a number of systemic functions

Sepsis is an excessive, dysregulated immune response to infection that activates inflammatory and coagulation cascades, which may lead to tissue injury, multiple organ dysfunction syndrome and death. Millions of individuals die annually of sepsis. To date, the only treatment available is antibiotics, drainage of the infection source when possible, and organ support in intensive care units. Numerous previous attempts to develop therapeutic treatments, directed at discreet targets of the sepsis cascade, could not cope with the complex pathophysiology of sepsis and failed. Here we describe a novel treatment, based on empty capsids of SV40 (nanocapsids - NCs). Studies in a severe rat sepsis model showed that pre-treatment by NCs led to a dramatic increase in survival, from zero to 75%. Transcript analyses (RNAseq) demonstrated that the NC treatment is a paradigm shift. The NCs affect multiple facets of biological functions. The affected genes are modified with time, adjusting to the recovery processes. The NCs effect on normal control rats was negligible. The study shows that the NCs are capable of coping with diseases with intricate pathophysiology. Further studies are needed to determine whether when applied after sepsis onset, the NCs still improve outcome.

Resveratrol Reduces Kidney Injury in a Rat Model of Uremia and is Associated with Increased Expression of Heat Shock Protein 70 (Hsp70)

BACKGROUND This study aimed to investigate the effects of resveratrol on kidney function in a rat model of uremia and the expression of heat shock proteins. MATERIAL AND METHODS The rat model of uremia was developed by 5/6 nephrectomy of Sprague-Dawley rats. The Hsp70 inhibitor MKT-077, a rhodacyanine dye, was used. The study groups included rats with sham surgery (the sham group), the rat model of uremia (the model group), the solvent-treated control group (the control group), the rat model treated with resveratrol group (the resveratrol group), the rat model treated with MKT-077 (the MKT-077 group), and the resveratrol+MKT-077 group. Kidney tissues were studied histologically. Renal cell apoptosis was detected by the TUNEL method. Expression of p53, Bax, and Bcl-2 mRNA and protein were detected by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and immunohistochemistry, respectively. RESULTS Compared with the sham group, the expression levels of heat shock proteins Hsp70, Hsp90, Hsp27, Hsp25, Hsp40, and Hsp60 in the kidney of the rat model group increased to different degrees. Compared with the model group, the Hsp70 levels in the resveratrol group were significantly increased (p<0.05). Compared with the model group, treatment with MKT-077 reduced the survival rate of rats, which was increased following resveratrol treatment. Compared with the resveratrol group, renal function in the resveratrol+MKT-077 group was significantly reduced (p<0.05). CONCLUSIONS In a rat model of uremia, resveratrol reduced renal injury and improved both renal function and survival, which were associated with increased expression of Hsp70.

Heat shock protein signaling in brain ischemia and injury

Heat shock proteins (HSPs) are chaperones that catalyze the refolding of denatured proteins. In addition to their ability to prevent protein denaturation and aggregation, the HSPs have also been shown to modulate many signaling pathways. Among HSPs, the inducible 70 kDa HSP (HSP70) has especially been shown to improve neurological outcome in experimental models of brain ischemia and injury. HSP70 can modulate various aspects of the programmed cell death pathways and inflammation. This review will focus on potential mechanisms of the neuroprotective effects of HSP70 in stroke and brain trauma models. We also comment on potential ways in which HSP70 could be translated into clinical therapies.

A New Approach for the Prevention and Treatment of Cardiovascular Disorders. Molecular Hydrogen Significantly Reduces the Effects of Oxidative Stress

Cardiovascular diseases are the most common causes of morbidity and mortality worldwide. Redox dysregulation and a dyshomeostasis of inflammation arise from, and result in, cellular aberrations and pathological conditions, which lead to cardiovascular diseases. Despite years of intensive research, there is still no safe and effective method for their prevention and treatment. Recently, molecular hydrogen has been investigated in preclinical and clinical studies on various diseases associated with oxidative and inflammatory stress such as radiation-induced heart disease, ischemia-reperfusion injury, myocardial and brain infarction, storage of the heart, heart transplantation, etc. Hydrogen is primarily administered via inhalation, drinking hydrogen-rich water, or injection of hydrogen-rich saline. It favorably modulates signal transduction and gene expression resulting in suppression of proinflammatory cytokines, excess ROS production, and in the activation of the Nrf2 antioxidant transcription factor. Although H2 appears to be an important biological molecule with anti-oxidant, anti-inflammatory, and anti-apoptotic effects, the exact mechanisms of action remain elusive. There is no reported clinical toxicity; however, some data suggests that H2 has a mild hormetic-like effect, which likely mediate some of its benefits. The mechanistic data, coupled with the pre-clinical and clinical studies, suggest that H2 may be useful for ROS/inflammation-induced cardiotoxicity and other conditions.

HSP70 protects rats and hippocampal neurons from central nervous system oxygen toxicity by suppression of NO production and NF-κB activation

During diving, central nervous system oxygen toxicity may cause drowning or barotrauma, which has dramatically limited the working benefits of hyperbaric oxygen in underwater operations and clinical applications. The aim of this study is to understand the effects and the underlying mechanism of heat shock protein 70 on central nervous system oxygen toxicity and its mechanisms in vivo and in vitro. Rats were given geranylgeranylacetone (800 mg/kg) orally to induce hippocampal expression of heat shock protein 70 and then treated with hyperbaric oxygen. The time course of hippocampal heat shock protein 70 expression after geranylgeranylacetone administration was measured. Seizure latency and first electrical discharge were recorded to evaluate the effects of HSP70 on central nervous system oxygen toxicity. Effects of inhibitors of nitric oxide synthase and nuclear factor-κB on the seizure latencies and changes in nitric oxide, nitric oxide synthase, and nuclear factor-κB levels in the hippocampus tissues were examined. In cell experiments, hippocampal neurons were transfected with a virus vector carrying the heat shock protein 70 gene (H3445) before hyperbaric oxygen treatment. Cell viability, heat shock protein 70 expression, nitric oxide, nitric oxide synthase, and NF-κB levels in neurons were measured. The results showed that heat shock protein 70 expression significantly increased and peaked at 48 h after geranylgeranylacetone was given. Geranylgeranylacetone prolonged the first electrical discharge and seizure latencies, which was reversed by neuronal nitric oxide synthase, inducible nitric oxide synthase and NF-κB inhibitors. Nitric oxide, nitric oxide synthase, and inducible nitric oxide synthase levels in the hippocampus were significantly increased after hyperbaric oxygen exposure, but reversed by geranylgeranylacetone, while heat shock protein 70 inhibitor quercetin could inhibit this effect of geranylgeranylacetone. In the in vitro study, heat shock protein 70-overexpression decreased the nitric oxide, nitric oxide synthase, and inducible nitric oxide synthase levels as well as the cytoplasm/nucleus ratio of nuclear factor-κB and protected neurons from hyperbaric oxygen-induced cell injury. In conclusion, overexpression of heat shock protein 70 in hippocampal neurons may protect rats from central nervous system oxygen toxicity by suppression of neuronal nitric oxide synthase and inducible nitric oxide synthase-mediated nitric oxide production and translocation of nuclear factor-κB to nucleus. Impact statement Because the pathogenesis of central nervous system oxygen toxicity (CNS-OT) remains unclear, there are few interventions available. To develop an efficient strategy against CNS-OT, it is necessary to understand its pathogenesis and in particular, the relevant key factors involved. This study examined the protective effects of heat shock protein 70 (HSP70) on CNS-OT via in vivo and in vitro experiments. Our results indicated that overexpression of HSP70 in hippocampal neurons may protect rats from CNS-OT by suppression of nNOS and iNOS-mediated NO production and the activation of NF-κB. These findings contribute to clarification of the role of HSP70 in CNS-OT and provide us a potential novel target to prevent CNS-OT. Clarification of the involvement of NO, NOS and NF-κB provides new insights into the mechanism of CNS-OT and may help us to develop new approach against it by interfering these molecules.

The 70-kDa heat shock protein (Hsp70) as a therapeutic target for stroke

The 70-kDa heat shock protein (Hsp70) is a cytosolic chaperone which facilitates protein folding, degradation, complex assembly, and translocation. Following stroke, these functions have the potential to lead to cytoprotection, and this has been demonstrated using genetic mutant models, direct gene transfer or the induction of Hsp70 via heat stress, approaches which limit its translational utility. Recently, the investigation of Hsp70-inducing pharmacological compounds, which, through their ability to inhibit Hsp90, has obvious clinical implications in terms of potential therapies to mitigate cell death and inflammation, and lead to neuroprotection from brain injury. Areas covered: In this review, we will focus on the role of Hsp70 in cell death and inflammation, and the current literature surrounding the pharmacological induction in acute ischemic stroke models with comments on potential applications at the clinical level. Expert opinion: Such neuroprotectants could be used to synergistically improve neurological outcome or to extend the time window of existing interventions, thus increasing the numbers of stroke victims eligible for treatment.

Heat shock proteins and kidney disease: perspectives of HSP therapy

Heat shock proteins (HSPs) mediate a diverse range of cellular functions, prominently including folding and regulatory processes of cellular repair. A major property of these remarkable proteins, dependent on intracellular or extracellular location, is their capacity for immunoregulation that optimizes immune activity while avoiding hyperactivated inflammation. In this review, recent investigations are described, which examine roles of HSPs in protection of kidney tissue from various traumatic influences and demonstrate their potential for clinical management of nephritic disease. The HSP70 class is particularly attractive in this respect due to its multiple protective effects. The review also summarizes current understanding of HSP bioactivity in the pathophysiology of various kidney diseases, including acute kidney injury, diabetic nephropathy, chronic glomerulonephritis, and lupus nephritis-along with other promising strategies for their remediation, such as DNA vaccination.

Tanshinone IIA pretreatment attenuates ischemia/reperfusion-induced renal injury

Tanshinone IIA is a chemical compound extracted from the root of traditional Chinese herb Salvia miltiorrhiza Bunge. Tanshinone IIA has been suggested to possess anti-inflammatory activity and antioxidizing capability. Recently, accumulating results have indicated the antitumor activity of tanshinone IIA; thus, it has attracted increasing attention. In addition, tanshinone IIA has been indicated to attenuate ischemia/reperfusion induced renal injury (I/RIRI); however, little is known regarding the underlying mechanisms involved in this process. In the present study an I/RIRI rat model was used to analyze the effects of tanshinone IIA on myeloperoxidase (MPO), TNF-α and IL-6 activities using ELISA kits. Furthermore, macrophage migration inhibitory factor (MIF), cleaved caspase-3, B-cell lymphoma 2 (Bcl-2) and p38 mitogen-activated protein kinase (MAPK) protein expression levels were evaluated using western blot analysis. The results indicated that tanshinone IIA protected renal function in I/RIRI rats. ELISA demonstrated that tanshinone IIA significantly reduced MIF, TNF-α and IL-6 activities in I/RIRI rats. Western blot analysis showed that tanshinone IIA significantly suppressed MIF, cleaved caspase-3 and p38 MAPK protein expression levels in I/RIRI rats. The present results suggest that tanshinone IIA pretreatment attenuates I/RIRI via the downregulation of MPO expression, inflammation, MIF, cleaved caspase-3 and p38 MAPK.

Cytosolic calcium transients are a determinant of contraction-induced HSP72 transcription in single skeletal muscle fibers

The intrinsic activating factors that induce transcription of heat shock protein 72 (HSP72) in skeletal muscle following exercise remain unclear. We hypothesized that the cytosolic Ca(2+) transient that occurs with depolarization is a determinant. We utilized intact, single skeletal muscle fibers from Xenopus laevis to test the role of the cytosolic Ca(2+) transient and several other exercise-related factors (fatigue, hypoxia, AMP kinase, and cross-bridge cycling) on the activation of HSP72 transcription. HSP72 and HSP60 mRNA levels were assessed with real-time quantitative PCR; cytosolic Ca(2+) concentration ([Ca(2+)]cyt) was assessed with fura-2. Both fatiguing and nonfatiguing contractions resulted in a significant increase in HSP72 mRNA. As expected, peak [Ca(2+)]cyt remained tightly coupled with peak developed tension in contracting fibers. Pretreatment with N-benzyl-p-toluene sulfonamide (BTS) resulted in depressed peak developed tension with stimulation, while peak [Ca(2+)]cyt remained largely unchanged from control values. Despite excitation-contraction uncoupling, BTS-treated fibers displayed a significant increase in HSP72 mRNA. Treatment of fibers with hypoxia (Po2: <3 mmHg) or AMP kinase activation had no effect on HSP72 mRNA levels. These results suggest that the intermittent cytosolic Ca(2+) transient that occurs with skeletal muscle depolarization provides a sufficient activating stimulus for HSP72 transcription. Metabolic or mechanical factors associated with fatigue development and cross-bridge cycling likely play a more limited role.

Insights into the role of heat shock protein 72 to whole-body heat acclimation in humans

Heat acclimation results in systemic and cellular adaptions that reduce the negative effect of heat and, consequently, the risk of heat illness. Although the classical changes observed with heat acclimation lead to increased tolerance to exercise in the heat by reducing heat storage (reflected in reduced core and skin temperatures) and increasing whole-body capacity for heat dissipation (greater plasma volume, sweat output, and skin blood flow), it appears that heat acclimation also induces changes at the cellular level that might increase tolerance of the whole organism to a higher core temperature for the development of fatigue. Thermotolerance is a process that involves increased resilience to an otherwise lethal heat stress that follows a sublethal exposure to heat. Thermotolerance is believed to be the result of increased content of heat shock proteins (Hsp), specially a member of the 70 kDa family, Hsp72 kDa. In humans, we and others have reported that heat acclimation increases intracellular Hsp72 levels. This increase in intracellular Hsp72 could improve whole-body organism thermotolerance by maintaining intestinal epithelial tight junction barriers, by increasing resistance to gut-associated endotoxin translocation, or by reducing the inflammatory response. In this review, we will initially provide an overview of the physiological adaptations induced by heat acclimation and emphasize the main cellular changes that occur with heat acclimation associated with intracellular accumulation of Hsp72. Finally, we will present an argument for a role of whole-body heat acclimation in augmenting cellular thermotolerance, which may protect vital organs from deleterious effects of heat stress in humans.

Heat-shock protein-70 and regulatory T cell-mediated protection from ischemic injury

Heat preconditioning induces heat-shock protein-70 upregulation and protects from renal ischemia/reperfusion injury. Kim et al. report that heat-shock protein-70 and regulatory T cells play a key role in protective heat preconditioning. This work reinforces the utility of inducing heat-shock protein-70 expression by pharmacological agents as a novel therapy for the prevention and treatment of ischemic kidney injury.

Single-dose oral quercetin improves redox status but does not affect heat shock response in mice

Inflammation and oxidative stress are considered as likely contributors to heat injury. However, their roles in regulating the heat shock response in vivo remain unclear. We tested the hypothesis that acute quercetin treatment would improve redox status and reduce heat shock responses in mice. Mice underwent two heat tests before and after single oral administration of either quercetin (15 mg/kg) or vehicle. We measured physiologic and biochemical responses in mice during and 18 to 22 hours after heat tests, respectively. There were no significant differences in core temperature, heart rate, or blood pressure between quercetin and vehicle groups during heat exposure. Mice with relatively severe hyperthermia during the pretreatment heat test showed a significant trend toward a lower peak core temperature during the heat test after quercetin treatment. Compared with mice not exposed to heat, quercetin-treated mice had significantly lower interleukin 6 (P < .01) and higher superoxide dismutase levels (P < .01), whereas vehicle-treated mice had significantly lower total glutathione and higher 8-isoprostane levels in the circulation after heat exposure. Heat exposure significantly elevated heat shock proteins (HSPs) 72 and 90 and heat shock factor 1 levels in mouse liver, heart, and skeletal muscles, but no significant differences in tissue HSPs and heat shock factor 1 were found between quercetin- and vehicle-treated mice. These results suggest that a single moderate dose of quercetin is sufficient to alter redox status but not heat stress response in mice. Acute adaptations of peripheral tissues to heat stress may not be mediated by systemic inflammatory and redox state in vivo.

The heat-shock protein-70-induced renoprotective effect is partially mediated by CD4+ CD25+ Foxp3 + regulatory T cells in ischemia/reperfusion-induced acute kidney injury

Recent reports suggest the presence of heat-shock protein (HSP)-reactive T cells with a regulatory phenotype in various inflammatory diseases. To test whether HSP exerts renoprotective effects through regulatory T cells (Tregs), ischemia/reperfusion injury was done with or without heat preconditioning in mice. Splenocytes from heat-preconditioned mice had Treg expansion and a reduced proliferative response upon mitogenic stimulus. T cells from heat-preconditioned mice failed to reconstitute postischemic injury when adoptively transferred to T cell-deficient nu/nu mice in contrast to those from control mice. Tregs were also increased in heat-preconditioned ischemic kidneys. Depleting Tregs before heat preconditioning abolished the renoprotective effect, while adoptive transfer of these cells back into Treg-depleted mice partially restored the beneficial effect of heat preconditioning. Inhibition of HSP70 by quercetin suppressed Treg expansion, as well as renoprotective effects. Transferring Tregs in quercetin-treated heat-preconditioned mice partially restored the beneficial effect of heat preconditioning. The specificity of immune cell HSP70 in renoprotection was confirmed by partial restoration of kidney injury when T cells from HSP70-deficient heat preconditioned mice were adoptively transferred to nu/nu mice. Thus, the renoprotective effect of HSP70 may be partially mediated by a direct immunomodulatory effect through Tregs. Better understanding of immunomodulatory mechanisms of various stress proteins might facilitate discovery of new preventive strategies in acute kidney injury.

Effect of astragalus and Panax notoginseng on expression of heat shock protein 70 and GAF in atrophic gastritis in rats

AIM: To evaluate the effect of astragalus, Panax notoginseng and their mixture on expression of heat shock protein 70 (HSP70) and GAF in atrophic gastritis in rats.

METHODS: Fifty-four healthy male Wistar rats were randomly divided into six groups: control group, model group, teprenone group, astragalus group, Panax notoginseng group and astragalus plus Panax notoginseng group. Atrophic gastritis was induced by implanting a pylorus spring and intragastrically administering hot salty starch paste. The control and model groups were given normal saline (2 mL) daily, while other groups were infused with water decoction of astragalus containing crude drug 3.5 g/(kg·d), the Panax notoginseng powder containing crude drug 0.7 g/(kg·d), Panax notoginseng powder and astragalus water decoction, and teprenone water suspension containing teprenone 200 mg/(kg·d) for one month by gavage, respectively. The expression of heat shock protein 70 and GAF in the rat gastric mucosa was measured using quantum dot immunofluorescence histochemical technology.

RESULTS: HSP70 protein expression in the astragalus, Panax notoginseng, astragalus plus Panax notoginseng and teprenone groups was significantly increased (all P < 0.05) compared to the model group. The expression of GAF in the astragalus, Panax notoginseng, astragalus plus Panax notoginseng and teprenone groups was also increased significantly compared to the model group (all P < 0.01). Although the expression of HSP70 in the astragalus group was higher than that in the Panax notoginseng group (P < 0.05), there was no significant difference in the expression of GAF between the two groups (P > 0.05).

CONCLUSION: Astragalus, Panax notoginseng and their combination can improve mucosal atrophy in rats with atrophic gastritis by increasing GAF and HSP70 expression. GAF and HSP70 may be potential therapeutic targets for atrophic gastritis.

Mild electrical stimulation and heat shock ameliorates progressive proteinuria and renal inflammation in mouse model of Alport syndrome

Alport syndrome is a hereditary glomerulopathy with proteinuria and nephritis caused by defects in genes encoding type IV collagen in the glomerular basement membrane. All male and most female patients develop end-stage renal disease. Effective treatment to stop or decelerate the progression of proteinuria and nephritis is still under investigation. Here we showed that combination treatment of mild electrical stress (MES) and heat stress (HS) ameliorated progressive proteinuria and renal injury in mouse model of Alport syndrome. The expressions of kidney injury marker neutrophil gelatinase-associated lipocalin and pro-inflammatory cytokines interleukin-6, tumor necrosis factor-α and interleukin-1β were suppressed by MES+HS treatment. The anti-proteinuric effect of MES+HS treatment is mediated by podocytic activation of phosphatidylinositol 3-OH kinase (PI3K)-Akt and heat shock protein 72 (Hsp72)-dependent pathways in vitro and in vivo. The anti-inflammatory effect of MES+HS was mediated by glomerular activation of c-jun NH₂-terminal kinase 1/2 (JNK1/2) and p38-dependent pathways ex vivo. Collectively, our studies show that combination treatment of MES and HS confers anti-proteinuric and anti-inflammatory effects on Alport mice likely through the activation of multiple signaling pathways including PI3K-Akt, Hsp72, JNK1/2, and p38 pathways, providing a novel candidate therapeutic strategy to decelerate the progression of patho-phenotypes in Alport syndrome.

The role of heat shock protein 90 in modulating ischemia-reperfusion injury in the kidney

INTRODUCTION

Kidney transplantation is the gold standard treatment for end-stage renal disease. Ischemia-reperfusion injury (IRI) is an unavoidable consequence of the transplantation procedure and is responsible for delayed graft function and poorer long-term outcomes.

AREAS COVERED

Pharmacological induction of heat shock protein (Hsp) expression is an emerging pre-conditioning strategy aimed at reducing IRI following renal transplantation. Hsp90 inhibition up-regulates protective Hsps (especially Hsp70) and potentially down-regulates NF-κB by disruption of the IκB kinase (IKK) complex. However, the clinical application of Hsp90 inhibitors is currently limited by their toxicity profile and the exact mechanism of protection conferred is unknown. Toll-like receptor 4 (TLR4) is a further regulator of NF-κB and recent studies suggest TLR4 plays a dominant role in mediating kidney damage following IRI. The full interaction of Hsps with TLRs is yet to be delineated and whether TLR4 signalling can be targeted by Hsp90 inhibition in IRI remains uncertain.

EXPERT OPINION

Pharmacological pre-conditioning by Hsp90 inhibition involves direct treatment to the kidney donor and/or organ, which aims to reduce injury prior to the onset of ischemia. The major challenges going forward are to establish the exact mechanism of protection offered by these drugs and the investgiation of less toxic analogues that could be safely translated into human studies.

The nephroprotective effect of tauroursodeoxycholic acid on ischaemia/reperfusion-induced acute kidney injury by inhibiting endoplasmic reticulum stress

The incidence of acute kidney injury (AKI) is very high, and multiple physiopathological processes are involved, including endoplasmic reticulum stress (ERS). Tauroursodeoxycholic acid (TUDCA) is an endogenous bile acid derivative that has been reported to inhibit ERS. To determine whether TUDCA had a nephroprotective effect on AKI and to explore the exact mechanism, an ischaemia/reperfusion (I/R)-induced AKI mouse model and a tunicamycin-pre-treated TCMK-1 cell model were established. It was found that the renal tubular necrosis score and cell apoptosis index reached their peak 24 hr after I/R. GRP78 and C/EBP homologous protein (CHOP) expression and Caspase 12 activation were enhanced, reaching their peaks at 4 and 12 hr, respectively. TUDCA intervention not only decreased the renal tubular necrosis score and the cell apoptosis index but also down-regulated GRP78 and CHOP expression and Caspase 12 activation. The survival rate of TCMK-1 cells pre-treated with TUDCA was significantly higher than that of TCMK-1 cells without TUDCA pre-treatment. In conclusion, TUDCA had a nephroprotective effect on IR-induced AKI by inhibiting ERS and by blocking GRP78 and CHOP expression, reducing Caspase 12 activation and inhibiting cell apoptosis.

Role of heat shock protein 70 in innate alloimmunity

This article briefly describes our own experience with the proven demonstration of heat shock protein 70 (HSP70) in reperfused renal allografts from brain-dead donors and reflects about its potential role as a typical damage-associated molecular pattern (DAMP) in the setting of innate alloimmunity. In fact, our group was able to demonstrate a dramatic up-regulation of HSP70 expression after postischemic reperfusion of renal allografts. Of note, up-regulation of this stress protein expression, although to a lesser extent, was already observed after cold storage of the organ indicating that this molecule is already induced in the stressed organism of a brain-dead donor. However, whether or not the dramatic up-regulation of HSP70 expression contributes to mounting an innate alloimmune response cannot be judged in view of these clinical findings. Nevertheless, HSP70, since generated in association with postischemic reperfusion-induced allograft injury, can be called a typical DAMP - as can every molecule be termed a DAMP that is generated in association with any stressful tissue injury regardless of its final positive or negative regulatory function within the innate immune response elicited by it. In fact, as we discuss in this article, the context-dependent, even contradistinctive activities of HSP70 reflect the biological phenomenon that, throughout evolution, mammals have developed an elaborate network of positive and negative regulatory mechanisms, which provide balance between defensive and protective measures against unwarranted destruction of the host. In this sense, up-regulated expression of HSP70 in an injured allograft might reflect a pure protective response against the severe oxidative injury of a reperfused donor organ. On the other hand, up-regulated expression of this stress protein in an injured allograft might reflect a (futile) attempt of the innate immune system to restore homeostasis with the aim to eliminate the "unwanted foreign allograft invader" by contributing to development of an adaptive alloimmune response. However, this adaptive immune response against donor histocompatibility alloantigens - in its evolutionary sense aimed to restore homeostasis - is by no means protective from a recipient's view point but tragically ends up with allograft rejection. Indeed: in this sense, allograft rejection is the result of a fateful confusion by the immune system of danger and benefit!

Heat-shock proteins in cardiovascular disease

Heat-shock proteins (HSPs) belong to a group of highly conserved families of proteins expressed by all cells and organisms and their expression may be constitutive or inducible. They are generally considered as protective molecules against different types of stress and have numerous intracellular functions. Secretion or release of HSPs has also been described, and potential roles for extracellular HSPs reported. HSP expression is modulated by different stimuli involved in all steps of atherogenesis including oxidative stress, proteolytic aggression, or inflammation. Also, antibodies to HSPs may be used to monitor the response to different types of stress able to induce changes in HSP levels. In the present review, we will focus on the potential implication of HSPs in atherogenesis and discuss the limitations to the use of HSPs and anti-HSPs as biomarkers of atherothrombosis. HSPs could also be considered as potential therapeutic targets to reinforce vascular defenses and delay or avoid clinical complications associated with atherothrombosis.

Effects of whole-body heat acclimation on cell injury and cytokine responses in peripheral blood mononuclear cells

To test the hypothesis that whole-body heat acclimation (HA) would increase peripheral blood mononuclear cells' (PBMC) tolerance to heat shock (HS) and/or alter the release of cytokines (IL-1β, IL-6, IL-10 and TNF-α) to bacterial lipopolysaccharide (LPS), we heat acclimated nine subjects by exercising them for 100 min in a hot environment for 10 days. The subjects' PBMC were separated and cultured on days 1 and 10 of HA pre- and post-exercise. Pre-exercise PBMC were allocated to three treatments: control (PRE, 37°C), HS (42.5°C for 2 h), or LPS (1 ng mL(-1) for 24 h). Post-exercise samples were incubated at 37°C. PBMC lactate dehydrogenase release increased (p < 0.05) after HS but it was not different (p > 0.05) between days 1 and 10 (0.100 ± 0.012 and 0.102 ± 0.16 abs., respectively). LPS treatment induced an increased (p < 0.05) release of cytokines but HA did not alter this response (p > 0.05). Pre-exercise intracellular heat shock protein 72 (Hsp72) was higher (p < 0.05) on day 10 compared to day 1 of HA (13 ± 5 and 8 ± 5 ng mL(-1), respectively). HS treatment caused a greater increase (p < 0.05) in Hsp72 than the exercise sessions on HA days 1 and 10. In addition, after HA, the Hsp72 response to HS was reduced (day 1, 129 ± 46; day 10, 80 ± 32 ng mL(-1), p < 0.05). In conclusion, HA increases PBMC Hsp72 but it does not reduce cellular damage to HS or alter cytokine response to LPS. We speculate that the stress applied during HA is not sufficient to modify the PBMC response.

Prolonged survival of allografts induced by mycobacterial Hsp70 is dependent on CD4+CD25+ regulatory T cells

Background

Heat shock proteins (Hsps) are stress induced proteins with immunomodulatory properties. The Hsp70 of Mycobacterium tuberculosis (TBHsp70) has been shown to have an anti-inflammatory role on rodent autoimmune arthritis models, and the protective effects were demonstrated to be dependent on interleukin-10 (IL-10). We have previously observed that TBHsp70 inhibited maturation of dendritic cells (DCs) and induced IL-10 production by these cells, as well as in synovial fluid cells.

Methodology/Principal Findings

We investigated if TBHsp70 could inhibit allograft rejection in two murine allograft systems, a transplanted allogeneic melanoma and a regular skin allograft. In both systems, treatment with TBHsp70 significantly inhibited rejection of the graft, and correlated with regulatory T cells (Tregs) recruitment. This effect was not tumor mediated because injection of TBHsp70 in tumor-free mice induced an increase of Tregs in the draining lymph nodes as well as inhibition of proliferation of lymph node T cells and an increase in IL-10 production. Finally, TBHsp70 inhibited skin allograft acute rejection, and depletion of Tregs using a monoclonal antibody completely abolished this effect.

Conclusions/Significance

We present the first evidence for an immunosuppressive role for this protein in a graft rejection system, using an innovative approach – immersion of the graft tissue in TBHsp70 solution instead of protein injection. Also, this is the first study that demonstrates dependence on Treg cells for the immunosuppressive role of TBHsp70. This finding is relevant for the elucidation of the immunomodulatory mechanism of TBHsp70. We propose that this protein can be used not only for chronic inflammatory diseases, but is also useful for organ transplantation management.

Circulating heat shock protein 70 (HSPA1A) in normal and pathological pregnancies

Heat shock proteins (Hsps) are ubiquitous and phylogenetically conserved molecules. They are usually considered to be intracellular proteins with molecular chaperone and cytoprotective functions. However, Hsp70 (HSPA1A) is present in the peripheral circulation of healthy nonpregnant and pregnant individuals. In normal pregnancy, circulating Hsp70 levels are decreased, and show a positive correlation with gestational age and an inverse correlation with maternal age. The capacity of extracellular Hsp70 to elicit innate and adaptive proinflammatory (Th1-type) immune responses might be harmful in pregnancy and may lead to the maternal immune rejection of the fetus. Decreased circulating Hsp70 level, consequently, may promote the maintenance of immunological tolerance to the fetus. Indeed, elevated circulating Hsp70 concentrations are associated with an increased risk of several pregnancy complications. Elevated Hsp70 levels in healthy pregnant women at term might also have an effect on the onset of labor. In preeclampsia, serum Hsp70 levels are increased, and reflect systemic inflammation, oxidative stress and hepatocellular injury. Furthermore, serum Hsp70 levels are significantly higher in patients with the syndrome of hemolysis, elevated liver enzymes, and low platelet count (HELLP syndrome) than in severely preeclamptic patients without HELLP syndrome. In HELLP syndrome, elevated serum Hsp70 level indicates tissue damage (hemolysis and hepatocellular injury) and disease severity. Increased circulating Hsp70 level may not only be a marker of these conditions, but might also play a role in their pathogenesis. Extracellular Hsp70 derived from stressed and damaged, necrotic cells can elicit a proinflammatory (Th1) immune response, which might be involved in the development of the maternal systemic inflammatory response and resultant endothelial damage in preeclampsia and HELLP syndrome. Circulating Hsp70 level is also elevated in preterm delivery high-risk patients, particularly in treatment-resistant cases, and may be a useful marker for evaluating the curative effects of treatment for preterm delivery. In addition, increased circulating Hsp70 levels observed in asthmatic pregnant patients might play a connecting role in the pathomechanism of asthmatic inflammation and obstetrical/perinatal complications. Nevertheless, a prospective study should be undertaken to determine whether elevated serum Hsp70 level precedes the development of any pregnancy complication, and thus can help to predict adverse maternal or perinatal pregnancy outcome. Moreover, the role of circulating Hsp70 in normal and pathological pregnancies is not fully known, and further studies are warranted to address this important issue.

Nrf2-dependent and -independent responses to nitro-fatty acids in human endothelial cells: identification of heat shock response as the major pathway activated by nitro-oleic acid

Electrophilic fatty acid derivatives, including nitrolinoleic acid and nitro-oleic acid (OA-NO(2)), can mediate anti-inflammatory and pro-survival signaling reactions. The transcription factor Nrf2, activated by electrophilic fatty acids, suppresses redox-sensitive pro-inflammatory gene expression and protects against vascular endothelial oxidative injury. It was therefore postulated that activation of Nrf2 by OA-NO(2) accounts in part for its anti-inflammatory actions, motivating the characterization of Nrf2-dependent and -independent effects of OA-NO(2) on gene expression using genome-wide transcriptional profiling. Control and Nrf2-small interfering RNA-transfected human endothelial cells were treated with vehicle, oleic acid, or OA-NO(2), and differential gene expression profiles were determined. Although OA-NO(2) significantly induced the expression of Nrf2-dependent genes, including heme oxygenase-1 and glutamate-cysteine ligase modifier subunit, the majority of OA-NO(2)-regulated genes were regulated by Nrf2-independent pathways. Moreover, gene set enrichment analysis revealed that the heat shock response is the major pathway activated by OA-NO(2), with robust induction of a number of heat shock genes regulated by the heat shock transcription factor. Inasmuch as the heat shock response mediates anti-inflammatory and cytoprotective actions, this mechanism is proposed to contribute to the protective cell signaling functions of nitro-fatty acids and other electrophilic fatty acid derivatives.

Klotho reduces apoptosis in experimental ischaemic acute kidney injury via HSP-70

BACKGROUND

High Klotho expression has been detected in the kidney, and since the results of a recent study suggested that Klotho induction mitigates ischaemic damage in the kidney, in the present study we explored the mechanism by which Klotho expression reduces renal ischaemia-reperfusion injury (IRI).

METHODS

Male mice were subjected to bilateral renal ischaemia for 30 min and reperfusion for 24 h, or to a sham operation. Both the IRI group and the sham group were intravenously injected with an adenovirus harbouring the mouse Klotho gene (ad-kl) before renal IRI. In addition, mIMCD3 cells induced to overexpress Klotho by transferring the Klotho gene with ad-kl were analysed by DNA microarray and real-time PCR. Renal expression of Klotho and several genes selected by DNA microarray were assessed by real-time PCR or Western blotting, and TUNEL staining was performed to assess apoptosis.

RESULTS

Prior administration of ad-kl to the mice resulted in robust induction of Klotho mRNA in the kidney and liver. Ad-kl transfer improved the plasma creatinine values and mitigated the histological damage and apoptosis induced by IRI. Expression of several genes was altered in mIMCD3 cells as a result of the change in Klotho expression, and expression of heat shock protein 70 (HSP70), in particular, was up-regulated in ad-kl mouse kidneys and HK2 cells.

CONCLUSION

The results suggest that Klotho is involved in the pathophysiology of IRI. Klotho mitigates apoptosis in experimental ischaemic acute kidney injury via expression of HSP70.

Pentobarbital reduces rhabdomyolysis-induced acute renal failure in conscious rats

BACKGROUND

Rhabdomyolysis is one of the causes of acute renal failure. Pentobarbital enhances the action of gamma-aminobutyric acid and suppresses the activities of nuclear factor (NF)-kappaB pathways. In this study, we used pentobarbital to study the effects on the glycerol-induced rhabdomyolysis with acute renal failure in conscious rats.

METHODS

Rhabdomyolysis was induced by intramuscular injection of 10 mL/kg of 50% glycerol in conscious rats. Ten minutes later, the rats received an intravenous injection of pentobarbital (10 mg/kg in 0.5 mL/h normal saline) or normal saline (0.5 mL/h). Biochemical substances, including blood urea nitrogen (BUN), creatinine (Cre), glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), and creatine phosphokinase (CPK) were measured at 0 hour, 1 hour, 3 hours, 6 hours, 12 hours, 24 hours, and 48 hours. Rats were killed by decapitation at 48 hours after glycerol administration, and the kidneys were removed immediately for pathological findings and immunohistochemistry.

RESULTS

Intramuscular injection of glycerol significantly increased blood BUN, Cre, GOT, GPT, CPK levels and induced severe histopathologic damage in the kidneys. NF-kappaB and inducible nitric oxide synthase (iNOS) were increased, and E-cadherin was decreased after glycerol administration, as detected by immunohistochemistry in the kidneys. Posttreatment with pentobarbital decreased blood BUN, Cre, GOT, GPT, CPK levels, decreased the markers of kidney injury, and suppressed the release of NF-kappaB and iNOS after rhabdomyolysis.

CONCLUSION

Posttreatment with pentobarbital suppressed the activities of NF-kappaB and iNOS, decreased BUN, Cre, GOT, GPT, CPK levels, and decreased the markers of kidney injury after rhabdomyolysis. These actions ameliorated rhabdomyolysis-induced acute renal failure in conscious rats.

Induction of heat shock proteins for protection against oxidative stress

Heat shock proteins (Hsps) have been studied for many years and there is now a large body of evidence that demonstrates the role of Hsp upregulation in tissue and cell protection in a wide variety of stress conditions. Oxidative stress is known to be involved in a number of pathological conditions, including neurodegeneration, cardiovascular disease and stroke, and even plays a role in natural aging. In this review we summarize the current understanding of the role of Hsps and the heat shock response (HSR) in these pathological conditions and discuss the therapeutic potential of an Hsp therapy for these disorders. However, although an Hsp based therapy appears to be a promising approach for the treatment of diseases that involve oxidative damage, there are some significant hurdles that must be overcome before this approach can be successful. For example, to be effective an Hsp based therapy will need to ensure that the upregulation of Hsps occurs in the right place (i.e. be cell specific), at the right time and to a level and specificity that ensures that all the important binding partners, namely the co-chaperones, are also present at the appropriate levels. It is therefore unlikely that strategies that involve genetic modifications that result in overexpression of specific Hsps will achieve such sophisticated and coordinated effects. Similarly, it is likely that some pharmaceutical inducers of Hsps may be too generic to achieve the desired specific effects on Hsp expression, or may simply fail to reach their target cells due to delivery problems. However, if these difficulties can be overcome, it is clear that an effective Hsp based therapy would be of great benefit to the wide range of depilating conditions in which oxidative stress plays a critical role.

Renal ischemia-induced cholesterol loading: transcription factor recruitment and chromatin remodeling along the HMG CoA reductase gene

Acute kidney injury evokes renal tubular cholesterol synthesis. However, the factors during acute kidney injury that regulate HMG CoA reductase (HMGCR) activity, the rate-limiting step in cholesterol synthesis, have not been defined. To investigate these factors, mice were subjected to 30 minutes of either unilateral renal ischemia or sham surgery. After 3 days, bilateral nephrectomy was performed and cortical tissue extracts were prepared. The recruitment of RNA polymerase II (Pol II), transcription factors (SREBP-1, SREBP-2, NF-kappaB, c-Fos, and c-Jun), and heat shock proteins (HSP-70 and heme oxygenase-1) to the HMGCR promoter and transcription region (start/end exons) were assessed by Matrix ChIP assay. HMGCR mRNA, protein, and cholesterol levels were determined. Finally, histone modifications at HMGCR were assessed. Ischemia/reperfusion (I/R) induced marked cholesterol loading, which corresponded with elevated Pol II recruitment to HMGCR and increased expression levels of both HMGCR protein and mRNA. I/R also induced the binding of multiple transcription factors (SREBP-1, SREBP-2, c-Fos, c-Jun, NF-kappaB) and heat shock proteins to the HMGCR promoter and transcription regions. Significant histone modifications (increased H3K4m3, H3K19Ac, and H2A.Z variant) at these loci were also observed but were not identified at either the 5' and 3' HMGCR flanking regions (+/-5000 bps) or at negative control genes (beta-actin and beta-globin). In conclusion, I/R activates the HMGCR gene via multiple stress-activated transcriptional and epigenetic pathways, contributing to renal cholesterol loading.

Uremia induces proximal tubular cytoresistance and heme oxygenase-1 expression in the absence of acute kidney injury

Acute kidney injury (AKI) induces adaptive responses within proximal tubular (PT) cells that serve to protect them from further ischemic or toxic damage. However, it is not known whether uremia, a potential consequence of AKI, independently alters susceptibility to tubular injury. To address this issue, we subjected CD-1 mice to bilateral ureteral transection (BUTx), which produces uremia (blood urea nitrogen approximately 150 mg/dl) in the absence of direct renal damage. PT segments were then isolated from BUTx and control mice and subjected to in vitro hypoxic injury. Additionally, "in vitro uremia" was modeled in isolated tubules or in cultured PT (HK-2) cells by addition of 1) peritoneal dialysate (obtained from mice with bilateral ureteral obstruction), 2) peritoneal fluid (from BUTx mice), or 3) normal human urine (pH 7.4, with and without boiling). Effects on injury severity (lactate dehydrogenase release) were assessed. Finally, because uremia is a prooxidant state, it was hypothesized that BUTx would increase renal lipid peroxidation (malondialdehyde) and induce heme oxygenase-1 (HO-1), a redox-sensitive cytoprotective protein. BUTx conferred striking protection against hypoxic damage. This could be partially modeled in tubules and HK-2 cells by induction of in vitro uremia. Urine's protective action was heat labile (largely destroyed by boiling). BUTx caused a tripling of renal malondialdehyde and HO-1 protein levels. Increased HO-1 transcription was likely involved, as indicated by a tripling of HO-1 mRNA and RNA polymerase II binding along the HO-1 gene (chromatin immunoprecipitation assay). "Gene-activating" histone modifications [H3K4 trimethylation (H3K4m3) and histone 2 variant (H2A.Z)] at HO-1 gene loci were also observed. Uremia, per se, can contribute to the AKI-induced cytoresistance. Low-molecular-weight, heat-labile, cytoprotective factor(s) and uremia-induced renal stress responses (e.g., HO-1 gene activation) are likely involved. Finally, renal HO-1 induction following AKI may reflect direct cell injury effects and adaptations to uremia.

Inhibition of NF-kappaB in fusogenic membrane glycoprotein causing HL-60 cell death: implications for acute myeloid leukemia

Viral fusogenic membrane glycoproteins (FMGs) are new therapeutic genes for the control of tumor growth, the cellular mechanisms mediating cell death is non-apoptotic. However, the precise molecular mechanism remains to be elucidated. Here, we showed overexpression of HSP70 in HL-60 cells mediated by Gibbon Ape leukemia virus hyperfusogenic envelope protein (GALV-FMG) inhibited the nuclear translocation of p65, the transcriptive activity of NF-kappaB and prevented the degradation of IkappaB. NF-kappaB may negatively regulate HSP70 expression, which made a positive feed back loop for expression of HSP70. FMG expression in HL-60 cells leaded to the formation of multinucleated syncytia and cell death, the main death mode of cells is necrosis. This form of cell death should be effective in vivo, gene therapy basing on FMG deserve further study for the treatment of AML.

DNA-free recombinant SV40 capsids protect mice from acute renal failure by inducing stress response, survival pathway and apoptotic arrest

Viruses induce signaling and host defense during infection. Employing these natural trigger mechanisms to combat organ or tissue failure is hampered by harmful effects of most viruses. Here we demonstrate that SV40 empty capsids (Virus Like Particles-VLPs), with no DNA, induce host Hsp/c70 and Akt-1 survival pathways, key players in cellular survival mechanisms. We postulated that this signaling might protect against organ damage in vivo. Acute kidney injury (AKI) was chosen as target. AKI is critical, prevalent disorder in humans, caused by nephrotoxic agents, sepsis or ischemia, via apoptosis/necrosis of renal tubular cells, with high morbidity and mortality. Systemic administration of VLPs activated Akt-1 and upregulated Hsp/c70 in vivo. Experiments in mercury-induced AKI mouse model demonstrated that apoptosis, oxidative stress and toxic renal failure were significantly attenuated by pretreatment with capsids prior to the mercury insult. Survival rate increased from 12% to >60%, with wide dose response. This study demonstrates that SV40 VLPs, devoid of DNA, may potentially be used as prophylactic agent for AKI. We anticipate that these finding may be projected to a wide range of organ failure, using empty capsids of SV40 as well as other viruses.

Regulation of apoptotic and inflammatory cell signaling in cerebral ischemia: the complex roles of heat shock protein 70

Although heat shock proteins have been studied for decades, new intracellular and extracellular functions in a variety of diseases continue to be discovered. Heat shock proteins function within networks of interacting proteins; they can alter cellular physiology rapidly in response to stress without requiring new protein synthesis. This review focuses on the heat shock protein 70 family and considers especially the functions of the inducible member, heat shock protein 72, in the setting of cerebral ischemia. In general, inhibiting apoptotic signaling at multiple points and up-regulating survival signaling, heat shock protein 70 has a net prosurvival effect. Heat shock protein 70 has both antiinflammatory and proinflammatory effects depending on the cell type, context, and intracellular or extracellular location. Intracellular effects are often antiinflammatory with inhibition of nuclear factor-kappaB signaling. Extracellular effects can lead to inflammatory cytokine production or induction of regulatory immune cells and reduced inflammation.

Single dose intravenous thioacetamide administration as a model of acute liver damage in rats

Thioacetamide (TAA) has been used extensively in the development of animal models of acute liver injury. Frequently, TAA is administered intraperitoneally to induce liver damage under anaesthesia. However, it is rarely administered by intravenous injection in conscious rats. The experiments in this study were designed to induce acute liver damage by single intravenous injection of TAA (0, 70 and 280 mg/kg) in unrestrained rats. Biochemical parameters and cytokines measured during the 60-h period following TAA administration, included white blood cells (WBC), haemoglobulin (Hb), platelet, aspartate transferase (GOT), alanine transferase (GPT), total bilirubin (TBIL), direct bilirubin (DBI), albumin, ammonia (NH3), r-glutamyl transpeptidase (r-GT), tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). Rats were sacrificed by decapitation 60 h after TAA administration and livers were removed immediately for pathology and immunohistochemical (IHC) examination. Another group of rats were sacrificed by decapitation 1, 6 and 24 h after TAA administration and livers were removed immediately for time course change of pathology and IHC examination. TAA significantly increased blood WBC, GOT, GPT, TBIL, DBIL, NH3, r-GT, TNF-alpha and IL-6 levels but decreased the blood Hb, platelet and albumin level. The levels of histopathological damage in the liver after intravenous TAA administration were also increased with a dose-dependent trend and more increased at 60 h after TAA administration. The levels of inducible nitric oxide synthase (iNOS) and nuclear factor-kappaB (NF-kappaB) detected by IHC in the liver after intravenous TAA administration were also increased with a dose-dependent trend and more increased at 1 h after TAA administration. Single intravenous TAA administration without anaesthesia is a restorable animal model which may be used to investigate acute liver damage.

Asialoerythropoietin prevents contrast-induced nephropathy

Strategies to prevent contrast-induced nephropathy (CIN) are suboptimal. Erythropoietin was recently found to be cytoprotective in a variety of nonhematopoietic cells, so it was hypothesized that the nonhematopoietic erythropoietin derivative asialoerythropoietin would prevent CIN. Nephropathy was induced in rats by injection of the radiocontrast medium Ioversol in addition to inhibition of prostaglandin and nitric oxide synthesis. Administration of a single dose of asialoerythropoietin before the induction of nephropathy significantly attenuated the resulting renal dysfunction and histologic renal tubular injury. Contrast-induced apoptosis of renal tubular cells was inhibited by asialoerythropoietin both in vivo and in vitro, and this effect was blocked by a Janus kinase 2 (JAK2) inhibitor in vitro. Furthermore, phospho-JAK2/signal transducer and activator of transcription 5 (STAT5) and heat-shock protein 70 increased after injection of asialoerythropoietin, suggesting that the effects of asialoerythropoietin may be mediated by the activation of the JAK2/STAT5 pathway. Overall, these findings suggest that asialoerythropoietin may have potential as a new therapeutic approach to prevent CIN given its ability to preserve renal function and directly protect renal tissue.

Endogenous signals released from necrotic cells augment inflammatory responses to bacterial endotoxin

Stressed cells undergoing necrosis release molecules that acts as endogenous danger signals to alert and activate innate immune cells. Both HMGB1 and HSP70 are induced in activated monocytes/macrophages and also are released from stressed or injured cells. We investigated whether HMGB1 and HSP70 released from necrotic monocytes/macrophages, can act as danger signals to mediate proinflammatory cytokine responses to bacterial endotoxin or lipopolysaccharide (LPS). We show that cell lysate, obtained from necrotic cells directly stimulates the proinflammatory cytokine and chemokine responses in human monocyte/macrophage cell line, THP-1, as revealed by the induction of TNF-alpha, IL-6 and IL-8 mRNA expression and protein production. In the presence of LPS, necrotic cell lysate induced a more robust increase in all three proteins. We found that HMGB1 and HSP70 were indeed present in the necrotic cell lysate and were responsible for the significant induction of the proinflammatory cytokine expression, as neutralization with antibodies against both proteins blocked the increase in the cytokine production seen after incubating LPS-stimulated cells with the necrotic cell lysate. We also found that the newly identified triggering receptor expressed on myeloid cells-1 (TREM-1) was involved in mediating the HMGB1- and HSP70-induced cytokine production. Blocking TREM-1 on THP-1 cells with a recombinant chimera prevented the increase in cytokine production, while simultaneous blocking of TLR4 and TREM-1 completely abolished the proinflammatory response, suggesting that TREM-1 synergizes with TLR4 to mediate the effects of such signals from necrotic cells. In addition, blocking HMGB1 or HSP70 simultaneously with TREM-1 did not decrease the cytokine level further, confirming the involvement of TREM-1 in mediating the effect of HMGB1 and HSP70. Although the interaction of HMGB1 and HSP70 with TREM-1 induced I kappa B alpha and p38 expression, both of which are required for the inflammatory cytokine expression, blockade of TREM-1 did not affect I kappa B alpha expression but markedly reduced p38 activation, as revealed by Western blot analysis. Together, these results demonstrate that HMGB1 and HSP70 released from necrotic cells function as endogenous danger signals to augment the proinflammatory responses in monocytes/macrophage and that TREM-1 relays such signals to the cytokine expression cascade. This mechanism may contribute to the amplification and persistence of the inflammatory response to bacterial infection.

Cell stress induced HSP are targets of regulatory T cells: A role for HSP inducing compounds as anti-inflammatory immuno-modulators?

T cell responses to heat shock proteins (HSP) have disease suppressive activities through production of anti-inflammatory cytokines in patients and in models of inflammatory diseases. There is evidence that the anti-inflammatory activity of HSP-specific T cells depends on their recognition of endogenous HSP epitopes as expressed by stressed cells at sites of inflammation. Previously, we have demonstrated that such T cells can be induced by conserved sequences of microbial HSP. Now we propose that drug induced up-regulation of endogenous HSP can contribute to anti-inflammatory T cell regulation.