Heat shock treatment suppresses angiotensin II-induced activation of NF-κB pathway and heart inflammation: a role for IKK depletion by heat shock?

Heat shock response during the resolution of inflammation and its progressive suppression in chronic-degenerative inflammatory diseases

The heat shock response (HSR) is a crucial biochemical pathway that orchestrates the resolution of inflammation, primarily under proteotoxic stress conditions. This process hinges on the upregulation of heat shock proteins (HSPs) and other chaperones, notably the 70 kDa family of heat shock proteins, under the command of the heat shock transcription factor-1. However, in the context of chronic degenerative disorders characterized by persistent low-grade inflammation (such as insulin resistance, obesity, type 2 diabetes, nonalcoholic fatty liver disease, and cardiovascular diseases) a gradual suppression of the HSR does occur. This work delves into the mechanisms behind this phenomenon. It explores how the Western diet and sedentary lifestyle, culminating in the endoplasmic reticulum stress within adipose tissue cells, trigger a cascade of events. This cascade includes the unfolded protein response and activation of the NOD-like receptor pyrin domain-containing protein-3 inflammasome, leading to the emergence of the senescence-associated secretory phenotype and the propagation of inflammation throughout the body. Notably, the activation of the NOD-like receptor pyrin domain-containing protein-3 inflammasome not only fuels inflammation but also sabotages the HSR by degrading human antigen R, a crucial mRNA-binding protein responsible for maintaining heat shock transcription factor-1 mRNA expression and stability on heat shock gene promoters. This paper underscores the imperative need to comprehend how chronic inflammation stifles the HSR and the clinical significance of evaluating the HSR using cost-effective and accessible tools. Such understanding is pivotal in the development of innovative strategies aimed at the prevention and treatment of these chronic inflammatory ailments, which continue to take a heavy toll on global health and well-being.

Design of an Herbal Preparation Composed by a Combination of Ruscus aculeatus L. and Vitis vinifera L. Extracts, Magnolol and Diosmetin to Address Chronic Venous Diseases through an Anti-Inflammatory Effect and AP-1 Modulation

Chronic venous disease (CVD) is an often underestimated inflammatory pathological condition that can have a serious impact on quality of life. Many therapies have been proposed to deal with CVD, but unfortunately the symptoms recur with increasing frequency and intensity as soon as treatments are stopped. Previous studies have shown that the common inflammatory transcription factor AP-1 (activator protein-1) and nuclear factor kappa-activated B-cell light chain enhancer (NF-kB) play key roles in the initiation and progression of this vascular dysfunction. The aim of this research was to develop a herbal product that acts simultaneously on different aspects of CVD-related inflammation. Based on the evidence that several natural components of plant origin are used to treat venous insufficiency and that magnolol has been suggested as a putative modulator of AP-1, two herbal preparations based on Ruscus aculeatus root extracts, and Vitis vinifera seed extracts, as well as diosmetin and magnolol, were established. A preliminary MTT-based evaluation of the possible cytotoxic effects of these preparations led to the selection of one of them, named DMRV-2, for further investigation. First, the anti-inflammatory efficacy of DMRV-2 was demonstrated by monitoring its ability to reduce cytokine secretion from endothelial cells subjected to LPS-induced inflammation. Furthermore, using a real-time PCR-based protocol, the effect of DMRV-2 on AP-1 expression and activity was also evaluated; the results obtained demonstrated that the incubation of the endothelial cells with this preparation almost completely nullified the effects exerted by the treatment with LPS on AP-1. Similar results were also obtained for NF-kB, whose activation was evaluated by monitoring its distribution between the cytosol and the nucleus of endothelial cells after the different treatments.

Chrysin ameliorates STZ-induced diabetes in rats: possible impact of modulation of TLR4/NF-κβ pathway

Background and purpose:

Growing evidence advocates that upregulation of toll-like receptor 4 (TLR4) has been suggested as a causative influence in the development and complications of diabetes mellitus. We aimed to study the antidiabetic activity of chrysin against streptozotocin (STZ)-induced diabetes via down-regulation of TLR4/nuclear factor (NF-κβ)/heat shock protein 70 (HSP70) pathway as well as modulation of clusters of differentiation 4 (CD4+) in rats.

Experimental approach:

Fifty rats were divided into five groups (n = 10). Group I, normal rats received a single intraperitoneal injection of buffer citrate; group II, STZ-induced diabetic rats; groups III-V, diabetic rats received glimepiride (0.5 mg/kg; p.o.) or chrysin (40 and 80 mg/kg; p.o.) respectively, for 10 days. Serum samples were extracted to determine nitric oxide (NO), malondialdehyde (MDA), and reduced glutathione (GSH), insulin, CD4+, TLR4, and NF-κβ. Pancreatic tissue samples were extracted to determine glucose transporter 2 (GLUT2). Part of the pancreas was kept in formalin for pathological studies.

Findings/Results:

An elevation in blood glucose, NO, and MDA serum levels and a reduction of pancreatic GLUT2 content, insulin, and GSH serum levels were observed in diabetic rats. STZ injection, also, showed an increase in serum TLR4, NF-κβ, and HSP70 levels and a reduction in serum CD4+ levels with pancreatic cells necrosis. These biochemical and histological changes were reversed in glimepiride and chrysin groups.

Conclusion and implications:

The present study proved that chrysin has a potent anti-diabetic effect through the elevation of insulin and GLUT2 levels, the reduction of oxidative stress, and the inflammatory pathways TLR4/NF-κβ/HSP70 with the regulation of CD4+.

Heat therapy: mechanistic underpinnings and applications to cardiovascular health

Cardiovascular diseases (CVD) are the leading cause of death worldwide, and novel therapies are drastically needed to prevent or delay the onset of CVD to reduce the societal and healthcare burdens associated with these chronic diseases. One such therapy is "heat therapy," or chronic, repeated use of hot baths or saunas. Although using heat exposure to improve health is not a new concept, it has received renewed attention in recent years as a growing number of studies have demonstrated robust and widespread beneficial effects of heat therapy on cardiovascular health. Here, we review the existing literature, with particular focus on the molecular mechanisms that underscore the cardiovascular benefits of this practice.

Acute effects of leg heat therapy on walking performance and cardiovascular and inflammatory responses to exercise in patients with peripheral artery disease

Lower-extremity peripheral artery disease (PAD) is associated with increased risk of cardiovascular events and impaired exercise tolerance. We have previously reported that leg heat therapy (HT) applied using liquid-circulating trousers perfused with warm water increases leg blood flow and reduces blood pressure (BP) and the circulating levels of endothelin-1 (ET-1) in patients with symptomatic PAD. In this sham-controlled, randomized, crossover study, sixteen patients with symptomatic PAD (age 65 ± 5.7 years and ankle-brachial index: 0.69 ± 0.1) underwent a single 90-min session of HT or a sham treatment prior to a symptom-limited, graded cardiopulmonary exercise test on the treadmill. The primary outcome was the peak walking time (PWT) during the exercise test. Secondary outcomes included the claudication onset time (COT), resting and exercise BP, calf muscle oxygenation, pulmonary oxygen uptake (V̇O2 ), and plasma levels of ET-1, interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α). Systolic, but not diastolic BP, was significantly lower (~7 mmHg, p < .05) during HT when compared to the sham treatment. There was also a trend for lower SBP throughout the exercise and the recovery period following HT (p = .057). While COT did not differ between treatments (p = .77), PWT tended to increase following HT (CON: 911 ± 69 s, HT: 954 ± 77 s, p = .059). Post-exercise plasma levels of ET-1 were also lower in the HT session (CON: 2.0 ± 0.1, HT: 1.7 ± 0.1, p = .02). Calf muscle oxygenation, V̇O2 , COT, IL-6, and TNF-α did not differ between treatments. A single session of leg HT lowers BP and post-exercise circulating levels of ET-1 and may enhance treadmill walking performance in symptomatic PAD patients.

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.

Cardioprotective Effect of Decorin in Type 2 Diabetes

Cardiomyopathy is the leading cause of increased mortality in diabetes. In the present study, we investigated the effects of decorin (DCN) gene therapy on left ventricular function, cardiac inflammation and fibrosis in type 2 diabetes. Type 2 diabetes was induced in male Wistar rats by high fat diet (HFD, 60% of calories as fat) and STZ (20 mg/kg, intraperitoneal). Diabetic rats were divided into (n=6 for each group) the control group, the GFP-treated group and the DCN-treated group, received intravenous injection of saline solution, recombinant adeno-associated viral (rAAV)-GFP, and rAAV-DCN, respectively. We evaluated cardiac inflammation, fibrosis, left ventricular function at 6 months after gene delivery. Results turned out that rAAV-DCN treatment attenuated diabetic cardiomyopathy with improved LV function compared with control animals, which might be related to the reduced cardiac inflammation and fibrosis. These protective effects were associated with TGFβ1 pathway (ERK1/2 and smad-2) and NF-κB pathway, which may due to the decreased activation level of IGF-IR, increased expression of PKC-α and Hsp70. In conclusion, our results show that rAAV-mediated DCN therapy may be beneficial in the treatment of Diabetic Cardiomyopathy.

Passive heat therapy protects against endothelial cell hypoxia-reoxygenation via effects of elevations in temperature and circulating factors

KEY POINTS

Accumulating evidence indicates that passive heat therapy (chronic use of hot tubs or saunas) has widespread physiological benefits, including enhanced resistance against novel stressors ('stress resistance'). Using a cell culture model to isolate the key stimuli that are likely to underlie physiological adaptation with heat therapy, we showed that both mild elevations in temperature (to 39°C) and exposure to serum from human subjects who have undergone 8 weeks of heat therapy (i.e. altered circulating factors) independently prevented oxidative and inflammatory stress associated with hypoxia-reoxygenation in cultured endothelial cells. Our results elucidate some of the mechanisms (i.e. direct effects of temperature vs. circulating factors) by which heat therapy seems to improve resistance against oxidative and inflammatory stress. Heat therapy may be a promising intervention for reducing cellular damage following ischaemic events, which has broad implications for patients with cardiovascular diseases and conditions characterized by 'chronic' ischaemia (e.g. peripheral artery disease, metabolic diseases, obesity).

ABSTRACT

Repeated exposure to passive heat stress ('heat therapy') has widespread physiological benefits, including cellular protection against novel stressors. Increased heat shock protein (HSP) expression and upregulation of circulating factors may impart this protection. We tested the isolated abilities of mild heat pretreatment and serum from human subjects (n = 10) who had undergone 8 weeks of heat therapy to protect against cellular stress following hypoxia-reoxygenation (H/R), a model of ischaemic cardiovascular events. Cultured human umbilical vein endothelial cells were incubated for 24 h at 37°C (control), 39°C (heat pretreatment) or 37°C with 10% serum collected before and after 8 weeks of passive heat therapy (four to five times per week to increase rectal temperature to ≥ 38.5°C for 60 min). Cells were then collected before and after incubation at 1% O₂ for 16 h (hypoxia; 37°C), followed by 20% O₂ for 4 h (reoxygenation; 37°C) and assessed for markers of cell stress. In control cells, H/R increased nuclear NF-κB p65 protein (i.e. activation) by 106 ± 38%, increased IL-6 release by 37 ± 8% and increased superoxide production by 272 ± 45%. Both heat pretreatment and exposure to heat therapy serum prevented H/R-induced NF-κB activation and attenuated superoxide production; by contrast, only exposure to serum attenuated IL-6 release. H/R also decreased cytoplasmic haemeoxygenase-1 (HO-1) protein (known to suppress NF-κB), in control cells (-25 ± 8%), whereas HO-1 protein increased following H/R in cells pretreated with heat or serum-exposed, providing a possible mechanism of protection against H/R. These data indicate heat therapy is capable of imparting resistance against inflammatory and oxidative stress via direct heat and humoral factors.

Deep Transcriptomic Analysis of Black Rockfish (Sebastes schlegelii) Provides New Insights on Responses to Acute Temperature Stress

In the present study, we conducted an RNA-Seq analysis to characterize the genes and pathways involved in acute thermal and cold stress responses in the liver of black rockfish, a viviparous teleost that has the ability to cope with a wide range of temperature changes. A total of 584 annotated differentially expressed genes (DEGs) were identified in all three comparisons (HT vs NT, HT vs LT and LT vs NT). Based on an enrichment analysis, DEGs with a potential role in stress accommodation were classified into several categories, including protein folding, metabolism, immune response, signal transduction, molecule transport, membrane, and cell proliferation/apoptosis. Considering that thermal stress has a greater effect than cold stress in black rockfish, 24 shared DEGs in the intersection of the HT vs LT and HT vs NT groups were enriched in 2 oxidation-related gene ontology (GO) terms. Nine important heat-stress-reducing pathways were significantly identified and classified into 3 classes: immune and infectious diseases, organismal immune system and endocrine system. Eight DEGs (early growth response protein 1, bile salt export pump, abcb11, hsp70a, rtp3, 1,25-dihydroxyvitamin d(3) 24-hydroxylase, apoa4, transcription factor jun-b-like and an uncharacterized gene) were observed among all three comparisons, strongly implying their potentially important roles in temperature stress responses.

Epigenetics of Subcellular Structure Functioning in the Origin of Risk or Resilience to Comorbidity of Neuropsychiatric and Cardiometabolic Disorders

Mechanisms controlling mitochondrial function, protein folding in the endoplasmic reticulum (ER) and nuclear processes such as telomere length and DNA repair may be subject to epigenetic cues that relate the genomic expression and environmental exposures in early stages of life. They may also be involved in the comorbid appearance of cardiometabolic (CMD) and neuropsychiatric disorders (NPD) during adulthood. Mitochondrial function and protein folding in the endoplasmic reticulum are associated with oxidative stress and elevated intracellular calcium levels and may also underlie the vulnerability for comorbid CMD and NPD. Mitochondria provide key metabolites such as nicotinamide adenine dinucleotide (NAD+), ATP, α-ketoglutarate and acetyl coenzyme A that are required for many transcriptional and epigenetic processes. They are also a source of free radicals. On the other hand, epigenetic markers in nuclear DNA determine mitochondrial biogenesis. The ER is the subcellular organelle in which secretory proteins are folded. Many environmental factors stop the ability of cells to properly fold proteins and modify post-translationally secretory and transmembrane proteins leading to endoplasmic reticulum stress and oxidative stress. ER functioning may be epigenetically determined. Chronic ER stress is emerging as a key contributor to a growing list of human diseases, including CMD and NPD. Telomere loss causes chromosomal fusion, activation of the control of DNA damage-responses, unstable genome and altered stem cell function, which may underlie the comorbidity of CMD and NPD. The length of telomeres is related to oxidative stress and may be epigenetically programmed. Pathways involved in DNA repair may be epigenetically programmed and may contribute to diseases. In this paper, we describe subcellular mechanisms that are determined by epigenetic markers and their possible relation to the development of increased susceptibility to develop CMD and NPD.

Reductive Stress in Inflammation-Associated Diseases and the Pro-Oxidant Effect of Antioxidant Agents

Abstract: Reductive stress (RS) is the counterpart oxidative stress (OS), and can occur in response to conditions that shift the redox balance of important biological redox couples, such as the NAD⁺/NADH, NADP⁺/NADPH, and GSH/GSSG, to a more reducing state. Overexpression of antioxidant enzymatic systems leads to excess reducing equivalents that can deplete reactive oxidative species, driving the cells to RS. A feedback regulation is established in which chronic RS induces OS, which in turn, stimulates again RS. Excess reducing equivalents may regulate cellular signaling pathways, modify transcriptional activity, induce alterations in the formation of disulfide bonds in proteins, reduce mitochondrial function, decrease cellular metabolism, and thus, contribute to the development of some diseases in which NF-κB, a redox-sensitive transcription factor, participates. Here, we described the diseases in which an inflammatory condition is associated to RS, and where delayed folding, disordered transport, failed oxidation, and aggregation are found. Some of these diseases are aggregation protein cardiomyopathy, hypertrophic cardiomyopathy, muscular dystrophy, pulmonary hypertension, rheumatoid arthritis, Alzheimer's disease, and metabolic syndrome, among others. Moreover, chronic consumption of antioxidant supplements, such as vitamins and/or flavonoids, may have pro-oxidant effects that may alter the redox cellular equilibrium and contribute to RS, even diminishing life expectancy.

Angiotensin-(1-7) prevents atrial tachycardia induced-heat shock protein 27 expression

OBJECTIVE

We aimed to investigate the effects of angiotensin-(1-7) [Ang-(1-7)] on heat-shock protein 27 (HSP27) in a canine model of induced tachycardia.

METHODS

Eighteen dogs were randomized into three equal treatment groups: sham, pacing and pacing+Ang-(1-7) group. The dogs in the last two groups were subjected to 2weeks of rapid atrial pacing (500bpm). The effects of Ang-(1-7) on HSP27 were assessed by real-time polymerase chain reaction and western blot.

RESULTS

The expression levels of atrial HSP27 mRNA and protein were significantly (P<0.05) higher for the pacing group than the sham group and significantly (P<0.05) lower for the pacing+Ang-(1-7) group than the pacing group. There was no significant difference between the HSP27 expression levels in the right and left atria among all three groups.

CONCLUSIONS

Our findings suggest that the overexpression of HSP27 may possibly be occurring as an adaptive response that allows atrial tissues to cope with rapid atrial pacing, and an inhibiting effect of Ang-(1-7) on atrial remodeling may be one of the mechanisms responsible for the attenuation of HSP27 up-regulation induced by rapid pacing.

Protein kinase D signaling in cancer: A friend or foe?

Protein kinase D is a family of evolutionarily conserved serine/threonine kinases that belongs to the Ca⁺⁺/Calmodulin-dependent kinase superfamily. Signal transduction pathways mediated by PKD can be triggered by a variety of stimuli including G protein-coupled receptor agonists, growth factors, hormones, and cellular stresses. The regulatory mechanisms and physiological roles of PKD have been well documented including cell proliferation, survival, migration, angiogenesis, regulation of gene expression, and protein/membrane trafficking. However, its precise roles in disease progression, especially in cancer, remain elusive. A plethora of studies documented the cell- and tissue-specific expressions and functions of PKD in various cancer-associated biological processes, while the causes of the differential effects of PKD have not been thoroughly investigated. In this review, we have discussed the structural-functional properties, activation mechanisms, signaling pathways and physiological functions of PKD in the context of human cancer. Additionally, we have provided a comprehensive review of the reported tumor promoting or tumor suppressive functions of PKD in several major cancer types and discussed the discrepancies that have been raised on PKD as a major regulator of malignant transformation.

Extracellular Release and Signaling by Heat Shock Protein 27: Role in Modifying Vascular Inflammation

Heat shock protein 27 (HSP27) is traditionally viewed as an intracellular chaperone protein with anti-apoptotic properties. However, recent data indicate that a number of heat shock proteins, including HSP27, are also found in the extracellular space where they may signal via membrane receptors to alter gene transcription and cellular function. Therefore, there is increasing interest in better understanding how HSP27 is released from cells, its levels and composition in the extracellular space, and the cognate cell membrane receptors involved in effecting cell signaling. In this paper, the knowledge to date, as well as some emerging paradigms about the extracellular function of HSP27 is presented. Of particular interest is the role of HSP27 in attenuating atherogenesis by modifying lipid uptake and inflammation in the plaque. Moreover, the abundance of HSP27 in serum is an emerging new biomarker for ischemic events. Finally, HSP27 replacement therapy may represent a novel therapeutic opportunity for chronic inflammatory disorders, such as atherosclerosis.

Oxidative DNA damage in kidneys and heart of hypertensive mice is prevented by blocking angiotensin II and aldosterone receptors

Introduction

Recently, we could show that angiotensin II, the reactive peptide of the blood pressure-regulating renin-angiotensin-aldosterone-system, causes the formation of reactive oxygen species and DNA damage in kidneys and hearts of hypertensive mice. To further investigate on the one hand the mechanism of DNA damage caused by angiotensin II, and on the other hand possible intervention strategies against end-organ damage, the effects of substances interfering with the renin-angiotensin-aldosterone-system on angiotensin II-induced genomic damage were studied.

Methods

In C57BL/6-mice, hypertension was induced by infusion of 600 ng/kg • min angiotensin II. The animals were additionally treated with the angiotensin II type 1 receptor blocker candesartan, the mineralocorticoid receptor blocker eplerenone and the antioxidant tempol. DNA damage and the activation of transcription factors were studied by immunohistochemistry and protein expression analysis.

Results

Administration of angiotensin II led to a significant increase of blood pressure, decreased only by candesartan. In kidneys and hearts of angiotensin II-treated animals, significant oxidative stress could be detected (1.5-fold over control). The redox-sensitive transcription factors Nrf2 and NF-κB were activated in the kidney by angiotensin II-treatment (4- and 3-fold over control, respectively) and reduced by all interventions. In kidneys and hearts an increase of DNA damage (3- and 2-fold over control, respectively) and of DNA repair (3-fold over control) was found. These effects were ameliorated by all interventions in both organs. Consistently, candesartan and tempol were more effective than eplerenone.

Conclusion

Angiotensin II-induced DNA damage is caused by angiotensin II type 1 receptor-mediated formation of oxidative stress in vivo. The angiotensin II-mediated physiological increase of aldosterone adds to the DNA-damaging effects. Blocking angiotensin II and mineralocorticoid receptors therefore has beneficial effects on end-organ damage independent of blood pressure normalization.

Angiotensin II, via angiotensin receptor type 1/nuclear factor-κB activation, causes a synergistic effect on interleukin-1-β-induced inflammatory responses in cultured mesangial cells

INTRODUCTION

The nuclear factor-κB (NF-κB) is an important regulator of the inflammatory response. Angiotensin II (Ang II) activates the NF-κB pathway linked to renal inflammation. Although both AT1 and AT2 receptors are involved in Ang II-mediated NF-κB activation, the biological processes mediated by each receptor are not fully characterized. Interleukin-1β (IL-1β) is an important macrophage-derived cytokine that regulates immune and inflammatory processes, activating intracellular pathways shared with Ang II, including the NF-κB.

MATERIALS AND METHODS

In vitro studies were done in primary cultured rat mesangial cells. NF-κB pathway was evaluated by phosphorylated levels of p65/IκB and DNA binding activity. The Ang II receptor subtype was determined by pretreatment with AT1 and AT2 antagonists.

RESULTS

In mesangial cells the simultaneous presence of Ang II and IL-1β caused a synergistic activation of the NF-κB pathway and a marked upregulation of proinflammatory factors under NF-κB control, including monocyte chemoattractant protein-1. The AT1, but not AT2, antagonist abolished the synergistic effect on NF-κB activation and proinflammatory genes caused by coincubation of Ang II and IL-1β.

CONCLUSIONS

These data indicates that Ang II, via AT1/NF-κB pathway activation, cooperates with IL-β to increase the inflammatory response in mesangial cells.

Bcl10 mediates angiotensin II-induced cardiac damage and electrical remodeling

Angiotensin (Ang) II is a potent mediator of both hypertension and cardiac damage; however, the mechanisms by which this occur remain unclear. B-cell lymphoma/leukemia 10 (Bcl10) is a member of the CBM signalosome, which links Ang II and nuclear factor-κB signaling. We hypothesized that Bcl10 is pivotal in the pathogenesis of Ang II-induced cardiac damage. Ang II infusion in mice lacking Bcl10 resulted in reduced cardiac fibrosis, less cellular infiltration, and improved arrhythmogenic electric remodeling, despite a similar degree of hypertension or cardiac hypertrophy. Adoptive transfer of bone marrow (BM), whereby Bcl10 knockout or wildtype BM was transferred to their opposite genotype recipients, revealed the dual importance of Bcl10 within both cardiac and immune cells. Loss of Bcl10 in cardiac cells resulted in reduced expression of genes important for the adhesion and recruitment of immune cells. In vitro experiments demonstrated that adhesion of monocytes to Ang II-treated endothelial cells also required Bcl10. Additionally, Bcl10 deficiency in macrophages reduced their intrinsic migratory ability. To address the role of BM-derived fibroblasts in the formation of cardiac fibrosis, we explored whether Bcl10 is also important for the infiltration of BM-derived (myo)fibroblasts into the heart. The transfer of green fluorescent protein positive wildtype BM into Bcl10 knockout recipient mice revealed a reduced number of noncardiac (myo)fibroblasts compared with those wildtype recipients. Our results demonstrate the significant role of Bcl10 in multiple cell types important for the generation of Ang II-induced cardiac damage and electric remodeling and may provide a new avenue for therapeutic intervention.

Heat shock prevents insulin resistance-induced vascular complications by augmenting angiotensin-(1-7) signaling

We have investigated the role of heat shock (HS) in preventing insulin resistance-induced endothelial dysfunction. To the best of our knowledge, we report here for the first time that insulin resistance inhibits vascular HS protein (HSP) 72 expression. HS treatment (41 °C for 20 min) restored the HSP72 expression. High-fat diet (HFD)-fed, insulin-resistant rats show attenuated angiotensin (ANG)-(1-7)-induced vasodilator effect, endothelial nitric oxide synthase (eNOS) phosphorylation, AMP-activated protein kinase phosphorylation, and sirtuin 1 (SIRT1) expression. Interestingly, HS prevented this attenuation. We also provide the first evidence that HFD-fed rats show increased vascular DNA methyltransferase 1 (DNMT1) expression and that HS prevented this increase. Our data show that in HFD-fed rats HS prevented loss in the expression of ANG-(1-7) receptor Mas and ACE2, which were responsible for vascular complications. Further, the inhibition of eNOS (l-N(G)-nitro-L-arginine methyl ester), Mas (A-779), and SIRT1 (nicotinamide) prevented the favorable effects of HS. This suggests that HS augmented ANG-(1-7) signaling via the Mas/eNOS/SIRT1 pathway. Our study, for the first time, suggests that induction of intracellular HSP72 alters DNMT1 expression, and may function as an epigenetic regulator of SIRT1 and eNOS expression. We propose that induction of HSP72 is a novel approach to prevent insulin resistance-induced vascular complications.

Modulation of haemodynamics, endogeneous antioxidant enzymes, and pathophysiological changes by selective inhibition of angiotensin II type 1 receptors in pressureoverload rats

Background

Constriction of the thoracic or abdominal aorta provides an experimental model of pressure-overload cardiac hypertrophy. Blockade of AT₁ receptors is beneficial in preventing target-organ damage in hypertension.

Objective

To examine the effect of angiotensin II receptor antagonists on blood pressure, endogenous antioxidant enzyme and histopathological changes in pressure-overload rats.

Methods

Pressure overload was produced by abdominal aortic banding (AAB) using a blunt 22-guage needle in male rats as a model of cardiac hypertrophy. After surgery, the AAB-induced hypertension (AABIH) rats were treated with losartan 40 mg/kg/day, candesartan 10 mg/kg/day, irbesartan 10 mg/kg/day per os for 16 weeks. At 16 weeks of surgery, the rats were observed for general characteristics and mortality, and we determined non-invasive blood pressure (NIBP), endogenous antioxidant enzyme catalase and superoxide dismutase (SOD) activities, and histology of the target organs.

Results

In the AABIH group, significant increase in systolic blood pressure was observed from weeks 3 to 16 compared with the control group, along with reduced serum catalase and SOD activities. The treated groups showed significant reduction in systolic BP and increase in serum SOD and catalase activities. The histological changes induced in the target organs, namely heart, liver, kidneys and thoracic aorta in the AABIH rats were attenuated in the treated rats.

Conclusion

Blockade of the AT₁ receptor caused an improvement in the myocardial antioxidant reserve and decreased oxidative stress in the hypertensive rats, which was evidenced by the protection observed in the treatment groups.

Impact of exercise and metabolic disorders on heat shock proteins and vascular inflammation

Heat shock proteins (Hsp) play critical roles in the body's self-defense under a variety of stresses, including heat shock, oxidative stress, radiation, and wounds, through the regulation of folding and functions of relevant cellular proteins. Exercise increases the levels of Hsp through elevated temperature, hormones, calcium fluxes, reactive oxygen species (ROS), or mechanical deformation of tissues. Isotonic contractions and endurance- type activities tend to increase Hsp60 and Hsp70. Eccentric muscle contractions lead to phosphorylation and translocation of Hsp25/27. Exercise-induced transient increases of Hsp inhibit the generation of inflammatory mediators and vascular inflammation. Metabolic disorders (hyperglycemia and dyslipidemia) are associated with type 1 diabetes (an autoimmune disease), type 2 diabetes (the common type of diabetes usually associated with obesity), and atherosclerotic cardiovascular disease. Metabolic disorders activate HSF/Hsp pathway, which was associated with oxidative stress, increased generation of inflammatory mediators, vascular inflammation, and cell injury. Knock down of heat shock factor-1 (HSF1) reduced the activation of key inflammatory mediators in vascular cells. Accumulating lines of evidence suggest that the activation of HSF/Hsp induced by exercise or metabolic disorders may play a dual role in inflammation. The benefits of exercise on inflammation and metabolism depend on the type, intensity, and duration of physical activity.

Inducible HSP70 antagonizes IL-1β cytocidal effects through inhibiting NF-kB activation via destabilizing TAK1 in HeLa cells

Background

Despite several reports describing the HSP70-mediated cytoprotection against IL-1, the precise mechanism for this phenomenon remains to be determined.

Methods/Principal Findings

Here we used HeLa cells, a human epithelial carcinoma cell line, to evaluate the role of inducible HSP70 in response of IL-1β stimulation. We found that inducible HSP70 antagonized the cytotoxicity of IL-1β and improved the survival of HeLa cells. Further investigation demonstrated that increased expression level of inducible HSP70 reduced the complex of TAK1 and HSP90, and promoted the degradation of TAK1 protein via proteasome pathway. By overexpression and RNAi knockdown, we showed that inducible HSP70 modulated the NF-kB but not MAPKs signalings through influencing the stability of TAK1 protein in HeLa cells. Moreover, overexpression of HSP70 attenuated the production of iNOS upon IL-1β stimulation, validating that inducible HSP70 serves as a cytopretective factor to antagonize the cytocidal effects of IL-1β in HeLa cells.

Conclusions/Significance

Our observations provide evidence for a novel signaling mechanism involving HSP70, TAK1, and NF-κB in the response of IL-1β cytocidal effects. This research also provides insight into mechanisms by which HSP70 exerts its cytoprotective action upon toxic stimuli in tumor cells.

Insulin Signaling, GSK-3, Heat Shock Proteins and the Natural History of Type 2 Diabetes Mellitus: A Hypothesis

Metabolic syndrome and type 2 diabetes are progressive, indolent, multi-organ diseases. Understanding the abnormalities of heat shock proteins (HSPs) in these diseases is paramount to understanding their pathogenesis. In insulin resistant states and diabetes, heat shock factor 1(HSF-1) is low in insulin sensitive tissues, resulting in low Hsp 60, 70, and 90 levels. We propose that low Hsps levels are the result of decreased insulin action leading to less phosphorylation of PI3K, PKB, and glycogen synthase kinase-3 (GSK-3). Importantly, less GSK-3 phosphorylation (and thus more GSK-3 activity) will lower HSF-1. Low Hsps make organs vulnerable to injury, impair the stress response, accelerate systemic inflammation, raise islet amyloid polypeptide, and increase insulin resistance. Feeding this cycle is excess saturated fat and calorie consumption, hypertension, inactivity, aging, and genetic predisposition- all of which are a associated with high GSK-3 activity and low Hsps. Support for the proposed "vicious" cycle is based on the observation that GSK-3 inhibition and Hsp stimulation result in increased insulin sensitivity, reduced accumulation of degenerative proteins with in the cell, improved wound healing, decreased organ damage and improved recovery from vascular ischemia. Recognizing GSK-3 and Hsps in the pathogenesis of insulin resistance, the central common feature of the metabolic syndrome, and type 2 diabetes will expand our understanding of the disease, offering new therapeutic options.

Heat shock factor-1 knockout induces multidrug resistance gene, MDR1b, and enhances P-glycoprotein (ABCB1)-based drug extrusion in the heart

Heat-shock factor 1 (HSF-1), a transcription factor for heat-shock proteins (HSPs), is known to interfere with the transcriptional activity of many oncogenic factors. In the present work, we have discovered that HSF-1 ablation induced the multidrug resistance gene, MDR1b, in the heart and increased the expression of P-glycoprotein (P-gp, ABCB1), an ATP binding cassette that is usually associated with multidrug-resistant cancer cells. The increase in P-gp enhanced the extrusion of doxorubicin (Dox) to alleviate Dox-induced heart failure and reduce mortality in mice. Dox-induced left ventricular (LV) dysfunction was significantly reduced in HSF-1(-/-) mice. DNA-binding activity of NF-κB was higher in HSF-1(-/-) mice. IκB, the NF-κB inhibitor, was depleted due to enhanced IκB kinase (IKK)-α activity. In parallel, MDR1b gene expression and a large increase in P-gp and lowering Dox loading were observed in HSF-1(-/-) mouse hearts. Moreover, application of the P-gp antagonist, verapamil, increased Dox loading in HSF-1(-/-) cardiomyocytes, deteriorated cardiac function in HSF-1(-/-) mice, and decreased survival. MDR1 promoter activity was higher in HSF-1(-/-) cardiomyocytes, whereas a mutant MDR1 promoter with heat-shock element (HSE) mutation showed increased activity only in HSF-1(+/+) cardiomyocytes. However, deletion of HSE and NF-κB binding sites diminished luminescence in both HSF-1(+/+) and HSF-1(-/-) cardiomyocytes, suggesting that HSF-1 inhibits MDR1 activity in the heart. Thus, because high levels of HSF-1 are attributed to poor prognosis of cancer, systemic down-regulation of HSF-1 before chemotherapy is a potential therapeutic approach to ameliorate the chemotherapy-induced cardiotoxicity and enhance cancer prognosis.

The heat shock paradox and cardiac myocytes: role of heat shock factor

The induction of the heat shock (HS) response is accepted to be a protective response, reducing injury and improving cell survival. However, when inflammation precedes HS, there is an unexpected increase in injury, known as the HS paradox, which is hypothesized to be a mechanism underlying multiorgan dysfunction. We hypothesized that the HS paradox would occur in adult cardiac myocytes and that HS factor (HSF) 1 would contribute to injury. Heat shock at 42°C and TNF (10 ng/mL) were used as the HS and the inflammatory insult, respectively. The combination of TNF followed by HS (TNF/HS) caused the greatest amount of apoptosis in adult rat cardiac myocytes. TNF/HS resulted in an increase in HS protein (HSP) 60, compared with untreated cells, those receiving HS/TNF, or TNF alone. There was no increase in heme oxygenase 1 in any of the groups. Heat shock protein 72 increased in all the groups, with the greatest levels with TNF/HS. Nuclear factor κB activation was greatest with TNF/HS. Pretreatment with a DNA-binding decoy for HSF-1 prevented the increase in HSPs and decreased apoptosis in all groups. However, the increase in iNOS, seen in all treatment groups, was unaffected by the HSF-1-binding decoy. We conclude that the HS paradox occurs in adult cardiac myocytes, that HSP60 is increased as part of the HS paradox, and that HSF-1 activation contributes to injury.

Heat shock proteins in stabilization of spontaneously restored sinus rhythm in permanent atrial fibrillation patients after mitral valve surgery

A spontaneously restored sinus rhythm in permanent atrial fibrillation patients has been often observed after mitral valve (MV) surgery, but persisting duration in sinus rhythm varies from patient to patient. Heat shock proteins (Hsps) may be involved in pathogenesis of atrial fibrillation. We hypothesized that stabilization of restored sinus rhythm is associated with expression of Hsps in the atria. To test this hypothesis, clinical data, biopsies of right atrial appendage, and blood samples were collected from 135 atrial fibrillation patients who spontaneously restored sinus rhythm after conventional isolated MV replacement. Comparison was made between patients who had recurrence of atrial fibrillation within 7 days (AF) vs. patients with persisted sinus rhythm for more than 7 days (SR). Results showed that SR patients had higher activity of heat shock transcription factor 1 (HSF1) as well as upregulated expressions of heat shock cognate 70, Hsp70, and Hsp27 in the tissues. The activation of HSF1-Hsps pathway was associated with less-aggressive pathogenesis as reflected by lower rates of myolysis, apoptosis, interstitial fibrosis, and inflammation in SR patients. However, Hsp60 was lower in both tissue and plasma in SR patients, and was positively correlated with apoptosis, interstitial fibrosis, and inflammation. These findings suggest that the Hsps play important roles in stabilization of restored sinus rhythm after MV surgery by inhibiting AF-related atrial remodeling and arrhythmogenic substrates in atrial fibrillation patients. Low circulating Hsp60 levels preoperatively might predict a stable spontaneously restored sinus rhythm postoperatively.

Hyperthermia-induced Hsp90·eNOS preserves mitochondrial respiration in hyperglycemic endothelial cells by down-regulating Glut-1 and up-regulating G6PD activity

Uncoupling of NO production from NADPH oxidation by endothelial nitric-oxide synthase (eNOS) is enhanced in hyperglycemic endothelium, potentially due to dissociation of heat shock proteins 90 (Hsp90), and cellular glucose homeostasis is enhanced by a ROS-induced positive feed back mechanism. In this study we investigated how such an uncoupling impacts oxygen metabolism and how the oxidative phosphorylation can be preserved by heat shock (42 °C for 2 h, hyperthermia) in bovine aortic endothelial cells. Normal and heat-shocked bovine aortic endothelial cells were exposed to normoglycemia (NG, 5.0 mM) or hyperglycemia (30 mM). With hyperglycemia treatment, O(2) consumption rate was reduced (from V(O(2)max) = 7.51 ± 0.54 to 2.35 ± 0.27 mm Hg/min/10(6) cells), whereas in heat-shocked cells, O(2) consumption rate remained unaltered (8.19 ± 1.01 mm Hg/min/10 × 10(6) cells). Heat shock was found to enhance Hsp90/endothelial NOS interactions and produce higher NO. Moreover, ROS generation in the hyperglycemic condition was also reduced in heat-shocked cells. Interestingly, glucose uptake was reduced in heat-shocked cells as a result of decrease in Glut-1 protein level. Glucose phosphate dehydrogenase activity that gives rise to NADPH generation was increased by hyperthermia, and mitochondrial oxidative metabolism was preserved. In conclusion, the present study provides a novel mechanism wherein the reduced oxidative stress in heat-shocked hyperglycemic cells down-regulates Glut-1 and glucose uptake, and fine-tuning of this pathway may be a potential approach to use for therapeutic benefit of diabetes mellitus.

PEGylated interferon-beta modulates the acute inflammatory response and recovery when combined with forced exercise following cervical spinal contusion injury

Secondary degeneration leads to an expansion of the initial tissue damage sustained during a spinal cord injury (SCI). Dampening the cellular inflammatory response that contributes to this progressive tissue damage is one possible strategy for neuroprotection after acute SCI. We initially examined whether treatment with a PEGylated form of rat interferon-beta (IFN-beta) would modulate the expression of several markers of inflammation and neuroprotection at the site of a unilateral cervical level 5 contusion injury. Adult female Sprague-Dawley rats were injured using the Infinite Horizon Impactor at a force of 200 kdyn (equivalent to a severe injury) and a mean displacement of 1600-1800 mum. A single dose (5x10(6) units) of PEGylated IFN-beta or vehicle was administered 30 min following SCI. Here we demonstrate temporal changes in pro- and anti-inflammatory cytokine levels and the expression of heat shock proteins and iNOS (involved in neuroprotection) at the lesion epicenter and one segment caudally after SCI and PEG IFN-beta treatment. The results suggested a potential therapeutic treatment strategy for modulation of secondary damage after acute SCI. Therefore, we examined whether acute treatment with PEG IFN-beta would improve forelimb function alone or when combined with forced exercise (Ex). Animals began the Ex paradigm 5 days post SCI and continued for 5 days/week over 8 weeks. Locomotion (forelimb locomotor scale [FLS], hindlimb BBB, and TreadScan) and sensorimotor function (grid walking) was tested weekly. Additional outcome measures included lesion size and glial cell reactivity. Significant FLS improvements occurred at 1 week post SCI in the PEGylated IFN-beta-treated group but not at any other time point or with any other treatment approaches. These results suggest that this acute neuroprotective treatment strategy does not translate into long term behavioral recovery even when combined with forced exercise.

Hyperthermia ameliorates 2,4,6-trinitrobenzene sulphonic acid-induced colitis in rats: The role of heat shock proteins

PURPOSE

Hyperthermia is known to protect against cellular injury through the expression of heat shock proteins. In this study, the therapeutic effects of hyperthermia on experimental colitis in the rat were evaluated.

MATERIALS AND METHODS

Male Wistar rats were given a single intracolonic injection of 2,4,6-trinitrobenzene sulphonic acid (TNBS). Hyperthermia was induced in anesthetized rats by placing them in a temperature-controlled water bath. We started the hyperthermic treatment on the day after the enema. The severity of colitis was evaluated pathologically, and the activities of tissue myeloperoxidase were measured 6 days after the induction of colitis. Furthermore, cytokines, and hyperthermia-induced heat shock proteins in colonic mucosa were detected by enzyme-linked immunosorbent assay and Western blotting. We also investigated the effects of geranylgeranylacetone and zinc protoporphyrin IX on the therapeutic effect of hyperthermia.

RESULTS

Hyperthermia significantly improved the macroscopic scores of colitis. The TNBS-induced increases in the activities of myeloperoxidase in the colonic tissue were blunted significantly in hyperthermia-treated animals. Furthermore, hyperthermia attenuated increases in cytokine-induced neutrophil chemoattractants-1 and tumor necrosis factor-alpha in the colon. Furthermore, hyperthermia induced the production of heat shock proteins in rat colonic mucosa, and the combination of geranylgeranylacetone with hyperthermia further induced the heat shock protein HSP70, which resulted in further improvement of TNBS-induced colitis. On the other hand, the combination of zinc protoporphyrin IX with hyperthermia attenuated the therapeutic effect of hyperthermia.

CONCLUSIONS

Hyperthermia ameliorates TNBS-induced colitis in rats through the expression of HSP70 and HO-1. It is postulated that hyperthermia may be useful for the treatment of inflammatory bowel diseases.

Hyperthermia attenuates TNF-alpha-induced up regulation of endothelial cell adhesion molecules in human arterial endothelial cells

BACKGROUND AND AIM

The activation of NF-kappaB induces production of inflammatory cytokines and up regulation of endothelial cell adhesion molecules (ECAM). ECAM (e.g., E-selectin, VCAM-1 and ICAM-1) associates to the recruitment of leukocytes into tissue exposed to inflammatory situation. In this study, we investigated the effects of hyperthermia on the activation of NF-kappaB and the up regulation of E-selectin and VCAM-1 in human endothelial cells stimulated by TNF-alpha.

METHODS

Human arterial endothelial cells (HAEC) were pretreated with hyperthermia for 60 min at 42 degrees C, followed by incubation at 37 degrees C in a passively cooled incubator, before TNF-alpha stimulation. To assess the effects of hyperthermia on TNF-alpha-induced up regulation of ECAM and TNF-alpha-induced activation of NF-kappaB, we measured ECAM by ELISA, and evaluated the activation of NF-kappaB by Western blotting after TNF-alpha stimulation. The accumulation of HO-1, Hsp70 and IkappaBalpha in hyperthermia-treated HAEC was also assessed by Western blotting. To investigate the role of Hsp70, we treated HAEC with geranylgeranylacetone (GGA, Hsp70 inducer) 2 h before hyperthermia, and then measured ECAM in TNF-alpha-stimulated HAEC by ELISA.

RESULTS

Pretreatment of hyperthermia reduced TNF-alpha-induced up regulation of E-selectin and VCAM-1. In addition, accumulation of Hsp70, HO-1 and IkappaBalpha protein were up-regulated after hyperthermia. Furthermore, Western blotting analysis revealed that pretreatment of hyperthermia attenuated TNF-alpha-induced translocation of p65 into the nuclei of HAEC. Moreover, GGA enhanced Hsp70 accumulation induced by hyperthermia. Hyperthermia pretreatment combined with GGA induced further inhibition of TNF-alpha-induced up regulation of ECAM when compared with hyperthermia alone.

CONCLUSION

Pretreatment of hyperthermia blocks TNF-alpha-induced NF-kappaB activation, resulting in the inhibition of ECAM up regulation in HAEC.

Early left ventricular gene expression profile in response to increase in blood pressure

The heart adapts to increased pressure overload by hypertrophic growth of terminally differentiated cardiomyocytes. At the genetic level, the hypertrophic response is characterized by the reprogramming of gene expression, i.e. upregulation of immediate early genes, natriuretic peptide genes and genes encoding structural proteins. In the present study, we characterized the early changes in gene expression with cDNA expression arrays in response to increase in blood pressure produced by arginine8-vasopressin infusion (0.05 microg/kg/min, i.v.) for 30 min and 4 h in conscious normotensive rats. Expression profiling revealed differential expression of 14 genes in the left ventricle, and several novel factors of immediate early genetic response to pressure overload were identified, such as growth arrest and DNA damage inducible protein 45 (GADD45alpha), epidermal fatty acid-binding protein (E-FABP) and Bcl-X. Administration of angiotensin II (Ang II) for 6 h by osmotic minipumps also increased left ventricular GADD45alpha, E-FABP and Bcl-X gene expression. Furthermore, the induction of GADD45alpha and Bcl-X gene expression by Ang II was blocked by angiotensin II type 1 receptor antagonist losartan. In summary, our analysis provided new insights into the pathogenesis of pressure overload-induced hypertrophy by suggesting the existence of novel regulators of the immediate early gene expression program.

Antitumor effect of pretreatment for colon cancer cells with hyperthermia plus geranylgeranylacetone in experimental metastasis models and a subcutaneous tumor model of colon cancer in mice

PURPOSE

We examined whether hyperthermia attenuated the metastatic potential of colon cancer through the induction of heat shock protein 70 (Hsp70).

MATERIALS AND METHODS

Colon26 cells were separated into four groups: (1) no pretreatment, (2) hyperthermia at 42 degrees C for 1 hour, (3) pretreatment with geranylgeranylacetone (GGA) 10(-6) M for 2 hours, and (4) hyperthermia after GGA treatment. We measured cell viabilities and the contents of Hsp70. We assessed nuclear factor-kappa-B (NF-kappa-B) status with and without tumor necrosis factor-alpha (TNF-alpha) stimulation. For in vivo study, colon26 cells were injected via the tail vein or into a subcutaneous area of mice and the numbers of lung metastatic nodules or the volumes of subcutaneous tumors were assessed. Untreated cells were incubated with PKH26. Experimental metastasis models were then generated and used to assess the fixed cancer cells.

RESULTS

Tumor development in the subcutaneous tumor models and cell viabilities were similar among the four groups. However, the GGA plus hyperthermia group had fewer lung metastatic nodules in the experimental lung metastasis model and higher Hsp70 induction than the other cell groups. The GGA plus hyperthermia pretreatment group also showed a lower number of fixed cells in lungs and lower activation of NF-kappa-B by TNF-alpha than the other cell groups.

CONCLUSIONS

It is suggested the metastatic potential but not the proliferation potency of cancer cells is inhibited by the transient induction of Hsp70.

Attenuation of lipopolysaccharide-mediated left ventricular dysfunction by glutamine preconditioning

OBJECTIVE

Myocardial dysfunction is often seen during the inflammatory response to major surgery at 4 to 6h postoperatively. The aim of this study was to investigate the effect of glutamine pretreatment, as a means of preconditioning, on lipopolysaccharide-induced myocardial dysfunction.

METHODS

C57BL/6 mice were randomized into four groups: Control; lipopolysaccharide; glutamine plus lipopolysaccharide; and Quercetin, an inhibitor of heat shock protein synthesis plus glutamine and lipopolysaccharide. Left ventricular function was assessed at 6h following lipopolysaccharide (LPS) insult by invasive hemodynamics. Heat shock protein (HSP)72 in heart tissue was determined by Western immunoblot at 12h after glutamine administration.

RESULTS

Administration of lipopolysaccharide resulted in significant decrease in left ventricular end systolic pressure (LVESP) (69.1 +/- 2.52 mm Hg versus 106.3 +/- 3.36 mm Hg in controls), reduced dP/dtmax (4704.1 +/- 425.31 mm Hg/s versus 9389.8 +/- 999.4 mm Hg/s in controls), and the increase in left ventricular end diastolic pressure (LVEDP) (5.10 +/- 0.28 mm Hg versus 2.16 +/- 0.27 mm Hg in controls) (P < 0.05). Peritoneal injection of 25 g/kg of glutamine 12 h prior to lipopolysaccharide exposure induced HSP72 expression in heart tissues and attenuated lipopolysaccharide-induced left ventricular dysfunction: LVESP 85.94 +/- 3.8 mm Hg (P < 0.05), dP/dtmax 8331 +/- 425 mm Hg (P < 0.05), LVEDP 2.32 +/- 0.23 mm Hg (P < 0.01). Quercetin partially attenuated glutamine induced HSP72 expression and blocked the protective response of glutamine.

CONCLUSION

These data demonstrate that cardioprotection with glutamine is associated with induction of HSP72 and may be an approach to activating the preconditioning response in the heart in clinical practise.

Heat shock proteins and exercise: a primer

Heat shock proteins (HSPs) are, in general, prosurvival molecules within the cellular environment, and the overexpression of even just 1 family of HSPs can lead to protection against and improvements after a variety of stressors. Not surprisingly, a fertile area of study has grown out of efforts to exploit the innate biologic behaviour of HSPs. Exercise, because of the inherent physiologic stresses associated with it, is but 1 stimulus that can result in a robust increase in various HSPs in several tissues, not the least of which happen to be the heart and skeletal muscle. The purpose of this review is to introduce the reader to the major HSP families, the control of their expression, and some of their biologic functions, specifically with respect to the influence of exercise. Moreover, as the first in a series of reviews from a common symposium, we will briefly introduce the concepts presented by the other authors, which include the effects of different exercise paradigms on skeletal muscle HSPs in the adult and aged systems, HSPs as regulators of inflammation, and the ion channel stabilizing effects of HSPs.

Heat shock proteins 27 and 70 regulating angiotensin II-induced NF-kappaB: a possible connection to blood pressure control?

Heat shock proteins (HSPs) are critical for cell survival and have several mechanisms of action. HSPs regulate protein folding, suppress apoptosis, and regulate anti-oxidative activity. In addition, HSPs are involved in the regulation of the pro-inflammatory transcription factor nuclear factor (NF)-kappaB. When angiotensin (Ang) II is infused into rats, there is a significant increase in systolic blood pressure, and NF-kappaB is activated in the heart. If rats are heat shocked to induce the heat shock response and HSPs before Ang II infusion, there is a significant suppression of both the Ang II-induced increase in blood pressure and NF-kappaB activation in the heart. Although the role of specific HSPs in the regulation of NF-kappaB is unclear, several HSPs, including Hsp27 and Hsp70, are thought to be involved in the regulation of Ang II-induced NF-kappaB. The role of Hsp27 and Hsp70 in NF-kappaB activation is reviewed here, along with evidence suggesting that HSPs regulate Ang II-induced blood pressure through the regulation of NF-kappaB.

Contribution of IL-6 to the Hsp72, Hsp25, and alphaB-crystallin [corrected] responses to inflammation and exercise training in mouse skeletal and cardiac muscle

The heat shock proteins (Hsps) Hsp72, Hsp25, and alphaB-crystallin (alphaB C) [corrected]may protect tissues during exercise and/or inflammatory insults; however, no studies have investigated whether exercise training increases both basal and inflammation-induced expression of these Hsps in skeletal or cardiac muscle. IL-6 is produced by muscle during both exercise and inflammation and has been shown to modulate Hsp expression. These studies tested the hypothesis that voluntary wheel running (RW) increases basal and inflammation-induced Hsp72, Hsp25, and alphaB C [corrected] protein through an IL-6-dependent mechanism. We compared Hsp72, Hsp25, alphaB C, [corrected] and IL-6 protein levels 4 h after systemic inflammation induced by lipopolysaccharide (LPS) in skeletal and cardiac muscles of wild-type (IL-6(+/+)) and IL-6 deficient (IL-6(-/-)) mice after 2 wk of RW or normal cage activity (Sed). LPS significantly increased skeletal Hsp72 and Hsp25 relative to saline in Sed IL-6(+/+), but not IL-6(-/-) mice. LPS increased Hsp72 relative to saline in Sed IL-6(+/+) cardiac muscle. RW increased basal Hsp72, Hsp25, and alphaB C [corrected] in skeletal muscle in IL-6(+/+) and IL-6(-/-) mice. However, LPS was not associated with increases in any Hsp in RW IL-6(+/+) or IL-6(-/-) mice. LPS increased IL-6 protein in skeletal muscle and plasma in Sed and RW groups, with a significantly greater response in RW. The major results provide the first in vivo evidence that the absence of IL-6 is associated with reduced skeletal muscle Hsp72 and Hsp25 responses to LPS, but that IL-6 is not required for exercise-induced Hsp upregulation in skeletal or cardiac muscle.

Lack of cross-tolerance following heat and cadmium exposure in functional MDCK monolayers

Exposure of monolayers of Madin-Darby canine kidney epithelial (MDCK) cells to a mild heat stimulus induces a state of physiological thermotolerance in which epithelial barrier function is maintained following a second more severe heat stress. We have previously shown that expression of exogenous HSP70 fully mimics the effects of the conditioning heat stress. Exposure of MDCK cells to elevated temperatures or medium containing CdCl2 caused a robust increase in cellular levels of HSP70. Pretreatment of MDCK monolayers with cadmium but not heat caused a small protection of epithelial barrier function against a second challenge with cadmium. In addition, a prior exposure of monolayers to cadmium at levels sufficient to induce HSP70 expression and increased cellular chaperone activity did not afford protection against a subsequent thermal challenge. Therefore multiple stress-specific cellular pathways impinge on the ability of heat shock proteins to induce physiological thermotolerance. Occludin, a component of tight junctions, is induced in MDCK cells engineered to express high levels of exogenous HSP70, potentially accounting for an elevation in baseline resistance. However neither basal levels of occludin, nor alterations in occludin expression, were correlated with epithelial barrier function in MDCK cells either exposed to elevated temperatures or challenged with cadmium.

Molecular mechanisms of felodipine suppressing atherosclerosis in high-cholesterol-diet apolipoprotein E-knockout mice

Oxidative stress and inflammation processes are key components of atherosclerosis, from fatty streak formation to plaque rupture and thrombosis. Evidence has revealed that calcium-channel blockers (CCB) could retard atherogenesis, but the exact mechanisms have not been fully elucidated. The present study was undertaken to investigate the potential effects and molecular mechanisms of the CCB felodipine on the process of atherosclerosis in high-cholesterol-diet (HCD) apolipoprotein E-knockout (ApoE KO) mice. Adult male ApoE KO mice were given a normal diet (ND) or HCD and were randomized to no treatment or felodipine (5 mg / kg per day for 12 weeks). The ApoE KO mice with HCD were associated with a marked increase in plasma lipid levels, atherosclerotic lesion area, and the expressions of NADPH oxidase subunits (p47 and Rac-1), nuclear factor-kappaB (NF-kappaB) in nucleus, phosphor-inhibitors of kappaB (p-IkappaB), tumor necrosis-alpha (TNF-alpha), monocyte chemoattractant protein-1 (MCP-1), and vascular cell-adhesion molecule-1 (VCAM-1). These changes were suppressed in mice that were treated with felodipine (5 mg/kg per day for 12 weeks) concomitant with HCD administration, with no significant change in systolic blood pressure and plasma lipid levels. The results suggest that felodipine can attenuate atherosclerosis, and this effect is partly related to inhibition of oxidative stress and inflammatory signal-transduction pathways, which lead to decreases in the expression of inflammatory cytokines.

PKD, PKD2, and p38 MAPK mediate Hsp27 serine-82 phosphorylation induced by neurotensin in pancreatic cancer PANC-1 cells

It is widely recognized that Hsp27 is a downstream substrate of the p38 MAPK cascade whereas the role of PKD family members in mediating receptor-stimulated Hsp27 Ser-82 phosphorylation has not been evaluated. Here, we show that neurotensin induced a rapid and striking increase in Hsp27 Ser-82 phosphorylation in PANC-1 cells, which was closely correlated with stimulation of activation loop phosphorylation of PKDs and p38 MAPK Thr180/Tyr182 phosphorylation. Treatment of PANC-1 cells with either the selective PKC inhibitor GF-I or the p38 MAPK inhibitor SB202190 partially reduced neurotensin-induced Hsp27 Ser-82 phosphorylation. However, treatment of the cells with a combination of GF-I and SB202190 virtually abolished neurotensin-induced Hsp27 Ser-82 phosphorylation. Overexpression of PKD in stably transfected PANC-1 cells increased the magnitude and prolonged the duration of Hsp27 Ser-82 phosphorylation in response to neurotensin. Either PKD or PKD2 gene silencing utilizing siRNAs targeting distinct PKD or PKD2 sequences reduced neurotensin-stimulated Hsp27 Ser-82 phosphorylation, but cotransfection of siRNAs targeting both, PKD and PKD2, markedly decreased neurotensin-induced Hsp27 Ser-82 phosphorylation. Knockdown of PKD and PKD2 abolished Hsp27 phosphorylation in cells treated with SB202190. Thus, neurotensin induces Hsp27 Ser-82 phosphorylation through p38 MAPK- and PKC/PKD-dependent pathways in PANC-1 cells. Our results demonstrate, for the first time, that neurotensin induces a striking increase in Hsp27 phosphorylation on Ser-82 in PANC-1 cells through convergent p38 MAPK, PKD, and PKD2 signaling.

Altered heat stress response following streptozotocin-induced diabetes

The heat shock response involves activation of heat shock transcription factor 1 (Hsf1) followed by the rapid synthesis of the protective heat shock proteins (Hsps). To determine if the stress experienced during streptozotocin (STZ)-induced diabetes altered the heat shock response, male Sprague-Dawley rats (n = 33; 280-300 g) were assigned to 4 groups: (1) control, (2) diabetic (30 days after 55 mg/kg STZ i.v.), (3) heat stressed (42 degrees C for 15 minutes), and (4) diabetic heat-stressed group (heat stressed 42 degrees C for 15 minutes, 30 days after 55 mg/kg STZ i.v.). The content of Hsp72, Hsp25, and Hsf1 in skeletal muscles, heart, kidney, and liver was assessed by Western blotting, while electrophoretic mobility shift gel analysis was used to assess Hsf activation. Without heat stress, the constitutive expression of Hsp25, Hsp72, and Hsf1 in tissues from diabetic animals and controls was similar. However, 24 hours following heat stress, the heart, kidney, and liver from diabetic animals showed an increased Hsp72 and Hsp25 content compared to the same tissues from heat-stressed nondiabetic animals (P < 0.05). The white gastrocnemius and plantaris muscles from heat-stressed animals (diabetic and nondiabetic) both showed significant and similar elevations in Hsp72 content. Interestingly, while all muscles from nondiabetic animals showed significant (P < 0.05) increase in Hsp25 content after heat stress, no increase in Hsp25 content was detected in muscles from heat-stressed diabetic animals. As expected, Hsf activation was undetectable in all tissues from non-heat-stressed animals but was detectable in tissues from both diabetic and nondiabetic animals following heat stress with the exception of diabetic skeletal muscle, where it was attenuated. Hsf1 content was unaltered in all tissues examined except in the white gastrocnemius muscles from heat-stressed diabetic animals, where it was undetectable. These results suggest that when tissues from STZ-induced diabetic animals are heat stressed, the Hsp/stress response is altered in a tissue-specific manner. This impaired ability to activate the stress response may explain, at least in part, the selective atrophy of certain muscles or muscle fiber types during diabetes.

Heat shock protein accumulation and heat shock transcription factor activation in rat skeletal muscle during compensatory hypertrophy

AIM

To assess the stress/heat shock protein (HSP) and heat shock factor activation response in overloaded (hypertrophied) plantaris muscles.

METHODS

Male Sprague-Dawley rats (n = 5 per time point) underwent unilateral removal of the left gastrocnemius muscle. After 1, 2, 3, 5, 7, 14 and 28 days, plantaris muscles were removed, weighted rapidly frozen in liquid nitrogen. Total protein content was determined and HSP 25 and HSP 72 contents were assessed by Western blotting. Heat shock transcription factor (HSF) activation was assessed by electrophoretic mobility shift assay (EMSA).

RESULTS

While plantaris muscle mass was significantly increased 3 days after the imposition of overload and remained elevated thereafter confirming muscle hypertrophy, muscle protein content was not increased until 7 days after the imposition of overload. HSP 72 content was significantly increased at 3 days, while HSP 25 content was not significantly increased until 7 days after synergistic muscle removal. HSF activation was detected at 1, 2 and 3 days of overload but undetectable thereafter. The addition of HSF1- and HSF2-specific antibodies to extracts prior to EMSA failed to supershift the HSF-heat shock element complex.

CONCLUSION

The temporal pattern of both HSF activation and HSP expression in skeletal muscle undergoing hypertrophy suggests the increased level of the observed HSPs may be both a consequence of both the immediate stress of overload and the hypertrophic process. The inability of HSF1- and HSF2-specific antibodies to cause supershifts suggests the HSF detected during overload may not be HSF1 or HSF2.

Hsp27 decreases inclusion body formation from mutated GTP-cyclohydrolase I protein

GTP cyclohydrolase I (GCH), an oligomeric protein composed of 10 identical subunits, is required for the synthesis of neurotransmitters; mutations in GCH are associated with dopa-responsive dystonia (DRD) and hyperphenylalaninemia. Mutated GCH proteins are unstable and prone to dominant-negative effect. We show herein that expression of the GCH mutant GCH-201E or the splicing variant GCH-II caused intracellular inclusion bodies. When Hsp27 was expressed together with the GCH mutants, Hsp27 expression decreased the formation of inclusion bodies by GCH (as assessed by immunofluorescence) and decreased the amount of insoluble GCH mutant proteins (as assessed by Western blot). Transfection of pcDNA-Hsp27-S3D, a phosphorylation-mimicry Hsp27 mutant, was more effective at the mutated GCH proteins than transfection with pcDNA-Hsp27, but okadaic acid, a phosphatase inhibitor, enhanced the effect of pcDNA-Hsp27. Hsp27-S3D also abolished the dominant-negative action of GCH-II. The mutated GCH proteins interacted with the wild-type GCH protein; the inclusion bodies were positive for lysosomal marker LAMP1, soluble in 2% SDS, and were not ubiquitinated. Phophorlyated Hsp27 also decreased the inclusion body formation by the huntingtin polyglutamines. Therefore, diseases involving mutated oligomeric proteins would be manageable by chaperone therapies.

Short-term heat exposure inhibits inflammation by abrogating recruitment of and nuclear factor-{kappa}B activation in neutrophils exposed to chemotactic cytokines

Cytokines, such as granulocyte macrophage-colony stimulating factor (GM-CSF) and interleukin (IL)-8 attract neutrophils into inflammatory sites. During emigration from the blood neutrophils interact with extracellular matrix proteins such as fibronectin. Fibronectin provides beta2-integrin co-stimulation, allowing GM-CSF and IL-8 to activate nuclear factor (NF)-kappaB, an effect that does not occur in suspension. We tested the hypothesis that exposure of mice to fever-like temperatures abrogates neutrophil recruitment and NF-kappaB activation in a mouse model of skin inflammation. Mice that were exposed to 40 degrees C for 1 hour showed strongly reduced GM-CSF- and IL-8-induced neutrophilic skin inflammation. In vitro heat exposure did not interfere with neutrophil adhesion or spreading on fibronectin but strongly inhibited migration toward both cytokines. Using specific inhibitors, we found that PI3-K/Akt was pivotal for neutrophil migration and that heat down-regulated this pathway. Furthermore, neutrophils on fibronectin showed abrogated NF-kappaB activation in response to GM-CSF and IL-8 after heat. In vivo heat exposure of mice followed by ex vivo stimulation of isolated bone marrow neutrophils confirmed these results. Finally, less NF-kappaB activation was seen in the inflammatory lesions of mice exposed to fever-like temperatures as demonstrated by in situ hybridization for IkappaBalpha mRNA. These new findings suggest that heat may have anti-inflammatory effects in neutrophil-dependent inflammation.

Hsp27 regulates pro-inflammatory mediator release in keratinocytes by modulating NF-kappaB signaling

Heat-shock protein 27 (Hsp27) is a member of the small Hsp family that functions as molecular chaperones and protects cells against environmental stress. Hsp27 is expressed in the upper epidermal layers of normal human skin and has been reported to play a role in keratinocyte differentiation and apoptosis. In this investigation, we show an additional role of Hsp27 in the regulation of inflammatory pathways in keratinocytes. Downregulation of Hsp27 using Hsp27-specific small interfering RNA increased prostaglandin E(2) (PGE(2)) production in both unstimulated and tumor necrosis factor-alpha (TNF-alpha)-stimulated keratinocytes. Moreover, downregulation of Hsp27 increased the release of the pro-inflammatory cytokine IL-8 from TNF-alpha-stimulated and UV-irradiated keratinocytes, and this increase was inhibited by pretreatment with the NF-kappaB inhibitor BAY11-7082. Further studies showed that downregulation of Hsp27 resulted in induction of NF-kappaB reporter activity in keratinocytes. This correlated with enhanced degradation of IkappaB-alpha protein and accumulation of phosphorylated IkappaB-alpha in Hsp27 knockdown cells. Moreover, Hsp27 associated with the IkappaB kinase (IKK) complex. As synthesis of the pro-inflammatory cytokine IL-8 and the prostanoid PGE(2) are regulated by NF-kappaB, this could be a probable mechanism by which Hsp27 modulates the production of these inflammatory cytokines. Thus, Hsp27 plays a protective role in regulating inflammatory responses in skin.

Heat shock treatment results in increased recruitment of labeled PMN following myocardial infarction

One of the proposed mechanisms for the myocardial protective effects of heat shock (HS) treatment has been a reduction in the inflammatory response. The objective of the present study was to evaluate the impact of HS treatment in an established model of polymorphonuclear cell (PMN) migration following myocardial infarction (MI). Isolated purified PMNs (10 x 10(6) cells) labeled with (51)Cr were injected into Lewis rats following a left thoracotomy and ligation of the left anterior descending coronary artery causing MI. Two experimental groups of animals were created: MI group (n = 11) and HS+MI group (n = 7). HS treatment consisted of an elevation in core temperature to 42 degrees C for 15 min 24 h prior to MI. An additional group of control animals underwent sham thoracotomy (n = 5). All animals were euthanized at 24 h after MI, and gamma counts were obtained to estimate PMN migration. Myocardial injury was confirmed in all experimental animals (histology and echocardiography). The serum troponin I and infarct size (triphenyltetrazolium chloride) were similar in both groups. Labeled PMN migration was significantly higher in HS+MI animals (14.3 x 10(4) +/- 3.7 x 10(4) PMN) compared with MI group (9.5 x 10(4) +/- 3.6 x 10(4); P = 0.01), suggesting increased PMN migration as a result of HS treatment. HS treatment did not affect PMN migration to positive skin control sites (LPS). ICAM-1 myocardial expression was not significantly increased in HS+MI compared with MI group. In summary, HS treatment results in increased PMN migration into myocardium following MI independent of ICAM-1. These findings suggest that the proposed cardioprotective effect of HS may not be entirely due to a downregulation of myocardial inflammation as previously proposed.

Expression of heat shock proteins in myocardium of patients with atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia. Because heat shock proteins (Hsp) can protect cells from stress, we compared the levels of Hsp60, Hsp72, Hsc73, and Hsp27 in atrial myocardium from 17 patients with AF (8 paroxysmal and 9 persistent) and 7 controls in sinus rhythm (SR). Hsp60, Hsp72, and Hsc73 levels were not significantly different among the 3 groups. Hsp27 expression was slightly higher in paroxysmal AF than in SR and in persistent AF, and a borderline significant difference (P = 0.064) was seen between the paroxysmal and persistent AF subgroups. Hsp60 levels in the moderate, severe, and profound myolysis groups were significantly lower than the light myolysis group, but no differences were found in other Hsps. In summary, the data indicate that expression of Hsp27 and Hsc73 may be associated with different stages of AF and that Hsp60 also may be associated with the degree of atrial myolysis.