Heat shock protein suppresses the senescent lung cytokine response to acute endotoxemia

DAMPs and neurodegeneration

The concept of neuroinflammation has come a full circle; from being initially regarded as a controversial viewpoint to its present day acceptance as an integral component of neurodegenerative processes. A closer look at the etiopathogenesis of many neurodegenerative conditions will reveal a patho-symbiotic relationship between neuroinflammation and neurodegeneration, where the two liaise with each other to form a self-sustaining vicious cycle that facilitates neuronal demise. Here, we focus on damage associated molecular patterns or DAMPs as a potentially important nexus in the context of this lethal neuroinflammation-neurodegeneration alliance. Since their nomenclature as "DAMPs" about a decade ago, these endogenous moieties have consistently been reported as novel players in sterile (non-infective) inflammation. However, their roles in inflammatory responses in the central nervous system (CNS), especially during chronic neurodegenerative disorders are still being actively researched. The aim of this review is to first provide a general overview of the neuroimmune response in the CNS within the purview of DAMPs, its receptors and downstream signaling. This is then followed by discussions on some of the DAMP-mediated neuroinflammatory responses involved in chronic neurodegenerative diseases. Along the way, we also highlighted some important gaps in our existing knowledge regarding the role of DAMPs in neurodegeneration, the clarification of which we believe would aid in the prospects of developing treatment or screening strategies directed at these molecules.

Riboflavin protects mice against liposaccharide-induced shock through expression of heat shock protein 25

Riboflavin (vitamin B2) is a water-soluble vitamin essential for normal cellular functions, growth and development. This study aimed to investigate the effects of vitamin B2 on the survival rate, and expressions of tissue heat shock protein 25 (HSP25) and heat shock factor 1 (HSF1) in mice undergoing lipopolysaccharide (LPS) induced shock. Mice were assigned to four groups, saline vehicle, LPS, LPS plus low dose of vitamin B2 (LB2) and LPS plus high dose of vitamin B2 (HB2). Vitamin B2 (1 and 10mg/kg BW) was administered intraperitoneally at 2 and 0 h before the i.p. administration of LPS. At the end of the experiment, the survival rate monitored was 10, 20, 60, and 100% for LPS, LB2, HB2, and saline mice, respectively. HSP25 expressions in the heart and lung were significantly enhanced in a time-dependent manner in the HB2 mice as compared to the saline mice (p < 0.05), but not altered in the LB2 mice. In the HB2 mice, plasma riboflavin concentrations reached 300 nM at 6h post LPS and returned to the 0 h level at 72 h. The results showed that high dose of riboflavin could decrease LPS-induced mortality through an increased expression of HSP25.

Effect of herbal medicine Juzentaihoto on hepatic and intestinal heat shock gene expression requires intestinal microflora in mouse

AIM: To evaluate the role of intestinal microflora in the effects of multi-herbal medicine on gene expression in the gut and liver.

METHODS: The multi-herbal medicine Juzentaihoto (JTX) was administered to five germ-free mice and regular mice for 2 wk. Among the results of the comprehensive gene chip analysis of the intestine and liver, we featured heat shock proteins (HSPs) 70 and 105 because their gene expression changed only in the presence of microflora. Real-time RT-PCR was performed to confirm the expression levels of these HSP genes. To determine whether JTX acts directly on the HSP genes, sodium arsenite (SA) was used to induce the heat shock proteins directly. To examine the change of the intestinal microflora with administration of JTX, the terminal restriction fragment polymorphism (T-RFLP) method was used. To identify the changed bacteria, DNA sequencing was performed.

RESULTS: Heat shock protein gene expression, documented by gene chip and real-time RT-PCR, changed with the administration of JTX in the regular mice but not in the germ-free mice. JTX did not suppress the direct induction of the HSPs by SA. T-RFLP suggested that JTX decreased unculturable bacteria and increased Lactobacillus johnsoni. These data suggested that JTX changed the intestinal microflora which, in turn, changed HSP gene expression.

CONCLUSION: Intestinal microflora affects multi-herbal product JTX on the gene expression in the gut and liver.

Role of ischaemic preconditioning in liver regeneration following major liver resection and transplantation

Liver ischaemic preconditioning (IPC) is known to protect the liver from the detrimental effects of ischaemic-reperfusion injury (IRI), which contributes significantly to the morbidity and mortality following major liver surgery. Recent studies have focused on the role of IPC in liver regeneration, the precise mechanism of which are not completely understood. This review discusses the current understanding of the mechanism of liver regeneration and the role of IPC in this setting. Relevant articles were reviewed from the published literature using the Medline database. The search was performed using the keywords “liver”, “ischaemic reperfusion”, “ischaemic preconditioning”, “regeneration”, “hepatectomy” and “transplantation”. The underlying mechanism of liver regeneration is a complex process involving the interaction of cytokines, growth factors and the metabolic demand of the liver. IPC, through various mediators, promotes liver regeneration by up-regulating growth-promoting factors and suppresses growth-inhibiting factors as well as damaging stresses. The increased understanding of the cellular mechanisms involved in IPC will enable the development of alternative treatment modalities aimed at promoting liver regeneration following major liver resection and transplantation.

Heat stress protects against lung injury in the neutropenic, endotoxemic rat

The objective of this study is to determine if heat stress prior to endotoxemia diminishes cardiopulmonary dysfunction by attenuating the cytokine inflammatory response. Rats were assigned to either: 1) neutropenia; 2) heat; 3) neutropenia, LPS; or 4) heat, neutropenia, LPS. Heart rate, blood gases, and blood, lung lavage, and lung mRNA for tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and macrophage inflammatory protein (MIP)-2 were measured. Heat given before LPS resulted in a similar A-a O(2) gradient as the heat-alone and neutropenic groups (8 +/- 8 versus 8 +/- 7 versus 4 +/- 3 mm Hg) and a lower A-a O(2) gradient when compared to the neutropenic, LPS rats (8 +/- 8 versus 22 +/- 8 mm Hg, p < 0.003). Blood, lung lavage, and lung mRNA for TNF-alpha, IL-1beta, and MIP-2 were similar in the LPS rats regardless of heat. Heart rate was similar in both LPS groups but higher than non-LPS groups. Heat pretreatment attenuates lung injury in the neutropenic, endotoxemic rat but not by decreasing TNF-alpha, IL-1beta, or MIP-2 in the lung. Heat prior to LPS did not prevent cardiac dysfunction in neutropenic rats.

How ischaemic preconditioning protects small liver grafts

Interleukin-1 (IL-1) and transforming growth factor-beta (TGFbeta) are key inhibitors of hepatocyte proliferation after hepatectomy. IL-1 inhibition by heat shock proteins (HSPs) has been reported in inflammatory processes. A recent study indicated the benefits of ischaemic preconditioning in reduced-size orthotopic liver transplantation (ROLT). The present study examined: (a) the effect of ischaemic preconditioning on IL-1 and TGFbeta in ROLT; (b) whether preconditioning protects small liver grafts through HSP induction; and (c) whether the potential benefits of preconditioning on HSP is related to IL-1 inhibition. Our results, obtained with an IL-1 receptor antagonist, indicated the injurious effects of IL-1 in ischaemia-reperfusion (I/R) injury and established a relationship between IL-1 and growth factors. Thus, IL-1 reduced hepatocyte growth factor (HGF) and promoted TGFbeta release, thus contributing to the impaired liver regeneration associated with ROLT. Preconditioning inhibited IL-1 through nitric oxide (NO), thereby protecting against the injurious effects of IL-1. In addition, by another pathway independent of NO, preconditioning induced HSP70 and haem-oxygenase-1 (HO-1). HO-1 protected against I/R injury and liver regeneration, whereas the benefits resulting from HSP70 were mainly related to hepatocyte proliferation. These results suggest a mechanism that explains the effectiveness of preconditioning in ROLT. They suggest, too, that other strategies, in addition to preconditioning, that modulate IL-1 and/or HSPs could be considered in clinical situations requiring liver regeneration such as small liver grafts.

Effect of zinc pretreatment on pulmonary endothelial cells in vitro and pulmonary function in a porcine model of endotoxemia

BACKGROUND

During endotoxemia, the systemic inflammatory response often leads to severe pulmonary damages. Destruction of endothelial cells, interstitial edema, and interstitial alveolitis depress pulmonary circulation and raise extravascular lung water and intrapulmonary shunt. As protective effects of zinc are described in vitro as well as in vivo, this study investigates its impact on septic porcine pulmonary endothelial monolayers as well as on the pulmonary function of endotoxemic pigs.

MATERIALS AND METHODS

Cell culture: Endothelial cells were incubated with ascending doses of zinc and pooled with septic plasma. Cellular damage, metabolism, and proliferation were measured by vital stain, XTT-assay, and BrDU-ELISA. HSP70 was visualized by immunohistochemistry. Animal study: We used an established porcine model. Twenty-four hours before endotoxemia (intravenous infusion of 1.0 microg/kg Escherichia coli endotoxin WO111:B4), each animal received an intravenous pretreatment. Group I (n = 3): saline pretreatment, group II (n = 5): zinc pretreatment (5 mg/kg elementary zinc). Monitoring included blood gas analysis and the thermal dye dilution technique.

RESULTS

In vitro, zinc leads to significantly altered rates of viable cells, metabolism, and proliferation with the strongest cell-protective effect at moderate concentrations of 1 microg/ml Zn2+. This correlates with a qualitatively increased expression of HSP70. In vivo, the zinc pretreatment before LPS-induced endotoxemia grossly improves all measured hemodynamic and pulmonary parameters.

CONCLUSION

Zinc pretreatment of endotoxemia decreases cellular damages in vitro and improved pulmonary function in vivo. This could be mediated by the heat shock response. Further studies, particularly concerning the dose-effect relationship and the underlying mode of action, are mandatory.

Evidence for a role of heat shock factor 1 in inhibition of NF-κB pathway during heat shock response-mediated lung protection

Heat shock transcription factor (HSF)-1 is recognized as a central component of the heat shock response, which protects against various harmful conditions. However, the mechanisms underlying the protection and the role of HSF-1 in these mechanisms have not yet been clearly elucidated. Using HSF-1 knockout mice ( Hsf1−/−), we examined whether heat shock response-mediated lung protection involved an inhibition of the proinflammatory pathway via an interaction between HSF-1 and NF-κB, in response to cadmium insult. The HSF-1-dependent protective effect against intranasal instillation of cadmium (10 and 100 μg/mouse) was demonstrated by the higher protein content (1.2- and 1.4-fold), macrophage (1.6- and 1.9-fold), and neutrophil (2.6- and 1.8-fold) number in bronchoalveolar fluids, higher lung wet-to-dry weight ratio, and more severe lung damage evaluated by histopathology in Hsf1−/−compared with wild-type animals. These responses were associated with higher granulocyte/macrophage colony-stimulating factor (GM-CSF; 1.7-fold) but not TNF-α concentrations in bronchoalveolar fluids of Hsf1−/−mice compared with those of wild-type animals, indicating that HSF-1 behaved as a repressor of specific cytokine production in our model. To further investigate the mechanism of GM-CSF repression, we analyzed the NF-κB activity and IκB stability. The DNA binding NF-κB activity, in particular p50 homodimer activity, was higher in Hsf1−/−mice than in wild-type mice after cadmium exposure. These results provide a first line of evidence that mechanisms of lung protection depending on HSF-1 involve specific cytokine repression via inhibition of NF-κB activation in vivo.

Overexpressed nuclear factor kappaB correlates with enhanced expression of interleukin-1beta and inducible nitric oxide synthase in aged murine lungs to endotoxic stress

BACKGROUND

Transcriptional regulation is a major determinant of interleukin-1beta (IL-1beta) protein synthesis. Nuclear factor kappaB (NF-kappaB) plays a central role in the regulation of IL-1beta and subsequent IL-1beta-dependent inflammatory processes. Previously, we observed in a murine endotoxic stress model a progressive increase with age in the amount of IL-1beta mRNA. We test the aging pulmonary response of NF-kappaB and NF-kappaB-dependent genes, IL-1beta, and inducible nitric oxide synthase (iNOS) in the same model.

METHODS

Young (2-month-old) and senescent (25-month-old) mice were given 0.5 mg/kg lipopolysaccharide (LPS) intraperitoneally. Lung and blood samples were harvested after 4 hours. IL-1beta production in blood samples and the expression levels of protein and mRNA of IL-1beta and iNOS in lung tissues were measured. NF-kappaB binding activity in lung tissues was also determined.

RESULTS

LPS induced higher levels of IL-1beta in the sera and lungs of senescent mice over young mice. Northern and Western blot analyses showed that mRNA and protein signals of IL-1beta and iNOS were significantly higher in old lungs than in young lungs. Electrophoretic mobility shift assay also showed that NF-kappaB activation was significantly higher in the older animals.

CONCLUSIONS

Our results suggest that elevated activation of NF-kappaB, at least in part, contributes to the dysregulated expression of IL-1beta and iNOS in the lungs of senescent animals. Thus increased expression of proinflammatory cytokines and inflammatory responsive genes in the lung may play a role in the increased susceptibility in aging animals to endotoxic stress.

Association of tumor necrosis factor gene polymorphisms and prolonged mechanical ventilation after coronary artery bypass surgery

OBJECTIVE

Prolonged mechanical ventilation is a common complication after coronary artery bypass graft surgery. Tumor necrosis factor alpha is an important proinflammatory mediator in the post-coronary artery bypass graft inflammatory cascade. We attempted to study the effect of polymorphisms at the -308 site in the promoter region of the tumor necrosis factor gene (TNF-308) and the +250 site within the lymphotoxin-alpha gene (LT alpha+250) on the risk of prolonged mechanical ventilation after coronary artery bypass grafting.

DESIGN

Prospective observational study.

SETTING

Tertiary care center.

PATIENTS

A total of 400 patients undergoing coronary artery bypass grafting were enrolled.

MEASUREMENTS

The primary end point was time to extubate. Secondary end points were the percentages of patients extubated at 8, 24, and 48 hrs; the length of intensive care unit and hospital stay; the need for a rehabilitation facility; and 30-day mortality. Precollected blood was used for gene analysis. Genotyping was performed by polymerase chain reaction and restriction enzyme digestion.

MAIN RESULTS

Patients with an AA genotype at the LT alpha+250 site and those without the LT alpha+250G/-308TNFG haplotype had a shorter duration of mechanical ventilation (11.5 vs. 27.8 hrs and 11.2 vs. 29.4 hrs; =.039 and.01, respectively). The risk of prolonged mechanical ventilation at 8, 24, and 48 hrs was higher for patients with a GA or GG genotype at the LT alpha+250 site and the LT alpha+250G/TNF-308G haplotype. This association between genotype and duration of mechanical ventilation was more dramatic in patients undergoing conventional coronary artery bypass grafting than in those undergoing off-pump coronary artery bypass grafting. With Bayesian analysis, clinical criteria and genotype can be used sequentially to predict the risk of prolonged mechanical ventilation.

CONCLUSIONS

The LT alpha+250 and LT alpha+250G/TNF-308G haplotypes are associated with prolonged mechanical ventilation after coronary artery bypass graft. Preoperative genetic screening may guide intraoperative management to reduce postoperative complications.

Age-related decrease in the inducibility of heat-shock protein 70 in human peripheral blood mononuclear cells

We have investigated the effect of age and of the presence of proinflammatory cytokines on Hsp 70 production in human peripheral blood mononuclear cells, using flow cytometry. Twenty-seven women and 23 men, all apparently healthy, participated in the study. At 37 degrees C, the percentage of Hsp 70-producing monocytes and lymphocytes, as well as the level of Hsp 70 in monocytes, were negatively influenced by age. After exposure of the cells to 42 degrees C, the increase of Hsp 70 production was more pronounced in monocytes than in lymphocytes; both the intensity of Hsp 70 production and the percentage of Hsp 70-producing cells were negatively influenced by the age of the subjects, as well for monocytes as for lymphocytes. There was a negative correlation between the intensity of Hsp 70 production by monocytes exposed to 42 degrees C and the serum levels of tumor necrosis factor-alpha and interleukin-6. In conclusion, in human monocytes and lymphocytes, heat-induced Hsp 70 production is reduced with increasing age and is negatively influenced in monocytes by proinflammatory cytokines.

Heat shock protein upregulation lowers cytokine levels after ischemia and reperfusion

OBJECTIVE

Studies showed that the expression of heat shock protein 70 (HSP70) by whole-body hyperthermia or warming of the heart is associated with protection against ischemia/reperfusion injury. The aim of this study is to determine a time-related response of HSP70 expression through topical cardiac warming with correlation to cytokine production.

METHODS

30 rats were divided into three groups: no heat shock, heat shocked, and controls. Heat shock was performed with 42 degrees C saline solution applied to the heart for 5, 30, and 60 min. HSP70 and cytokines were measured.

RESULTS

Heat shock treated animals showed a 1.2-fold increase after 5 min (NS) in HSP70 expression, a 2.0-fold increase (p < 0.02) after 30 min, and a 2.3-fold increase (p < 0.012) after 60 min compared to controls. The IL-1beta levels decreased from 14.3 pg/ml (normal controls) to 7.1 pg/ml after 5 min, to 1.6 pg/ml after 30 min (p < 0.002), and to 1.4 pg/ ml after 60 min of heat shock treatment (p < 0.002). The TNF-alpha levels also decreased, but not significantly.

CONCLUSIONS

Upregulation of HSP70 through this novel method is instant and detectable within hours. The amount of HSP70 expression induced is time dependent, showing an indirect correlation with cytokine levels. These results suggest that the protective effect of HSP70 is immediate and might be explained by reduced cytokine levels. No prior recovery period is needed.