Heat shock protein induction protects human respiratory epithelium against nitric oxide-mediated cytotoxicity

Heat shock protein 70 dampens the inflammatory response of human PDL cells to mechanical loading in vitro

BACKGROUND AND OBJECTIVE

Previously, we demonstrated an inflammatory response of human PDL (hPDL) cells to mechanical loading. The cellular reaction was dampened by heat pre-treatment suggesting a protective role for heat shock proteins (HSP) during stress-induced ischemia. Here we explored if HSP70, which has already been documented in the pressure zone of tooth movement, might be regulatorily involved in the attenuation of the inflammatory response.

MATERIALS AND METHODS

Fifth passage hPDL cells were mechanically loaded in the presence of the HSP70 inhibitor VER155008. Cell morphology, HSP70 expression, viability, IL-6 and IL-8 expression were determined by means of microscopy, realtime-PCR and ELISA. The conditioned medium of mechanically loaded and pre-treated hPDL cells was used to culture monocytes to identify a potential impact on adhesion and osteoclastic differentiation capacity.

RESULTS

Mechanical cell stress resulted in a significant increase of pro-inflammatory parameters. HSP70 inhibition led to a further enhancement of cytokine expression. The conditioned medium of mechanically loaded hPDL cells significantly increased monocyte adhesion and differentiation along the osteoclastic pathway. VER155008 pronounced this effect significantly.

CONCLUSION

The results indicate a regulatory role for HSP70 in the control of the inflammatory hPDL cell response to mechanical loading and identify HSP70 as a target in the attempt to attenuate tissue damage during orthodontic tooth movement. Furthermore, the present findings point to the risk of increased periodontal destruction when medication targeting HSP70 is applied for severe medical conditions during orthodontic tooth movement.

Role of HSP70 protein in human periodontal ligament cell function and physiology

OBJECTIVE

Heat pre-treatment of mechanically loaded human periodontal ligament cells (hPDL) dampens the inflammatory cellular response, as evidenced by a reduced expression of pro-inflammatory cytokines, inhibition of monocyte adhesion and osteoclastic differentiation. These findings imply heat shock proteins (HSP) as cell protective molecules acting in the PDL that are up-regulated upon ischemia caused by mechanical loading. HSP70 and its inhibition by VER155008 as the active agent in several pharmaceuticals are established targets and strategies, respectively, in the treatment of neoproliferative diseases. However, the effect of both players on periodontal remodeling in unknown. Therefore, we analyzed the role of HSP70 and its frequently used inhibitor VER155008 in the regulation of physiological hPDL cell functions and immune cell interaction.

MATERIALS AND METHODS

Fifth passage hPDL cells were cultured in the presence of 25μm HSP70 inactivating agent VER155008. At harvest, HSP70 expression, cell proliferation, and parameters of cell interaction, colony formation and wound healing were analyzed by means of real-time PCR, immunohistochemistry, Western blot, biochemical MTS assay, microscopy, and functional assays for monocyte adhesion and differentiation.

RESULTS

Basal HSP70 expression and hPDL cell morphology were not affected by HSP70 inhibitor VER155008. In contrast, cell proliferation, tissue defect healing, and colony formation were reduced significantly following HSP70 inhibition, whereas apoptosis and necrosis, monocyte adhesion and osteoclastic differentiation were markedly increased.

CONCLUSIONS

The present data indicate a regulatory role for HSP70 protein in hPDL cell biology.

CLINICAL RELEVANCE

These findings identify HSP70 as a promising target in the attempt to modify periodontal remodeling and point to potential periodontal side effects of HSP70 pharmaceutical usage.

Short-term heat pre-treatment modulates the release of HMGB1 and pro-inflammatory cytokines in hPDL cells following mechanical loading and affects monocyte behavior

OBJECTIVE

Heat shock proteins (HSP) act as cell-protective molecules that are upregulated upon thermal insult, hypoxia, and ischemia. Such ischemic conditions can be found during tissue remodeling associated with orthodontic tooth movement or trauma when compression forces lead to cell necrosis and subsequent clearance of cellular debris by immune competent cells. Host immune overreaction can result in undesired side effects such as tooth root resorption. Here, we analyzed whether heat pre-treatment would affect the initially catabolic host immune response induced by mechanical loading of human periodontal ligament (hPDL) cells, which represent major constituents of the tooth supporting apparatus involved in the regulation of periodontal remodeling.

MATERIALS AND METHODS

Fifth passage hPDL cells were exposed to an elevated temperature of 43° for 1 h prior to mechanical loading. Cell morphology, high mobility group box protein 1 (HMGB1), interleukin (IL)-6, and IL-8 expression were analyzed microscopically and by ELISA. The physiological relevance for monocyte behavior was tested in monocyte adhesion and osteoclast differentiation assays.

RESULTS

Short-term heat pre-treatment did not show any visible effect on hPDL cell morphology, but resulted in a significant downregulation of pro-inflammatory cytokines when being additionally loaded mechanically. Supernatants of heat-exposed hPDL cell cultures demonstrated a reduced impact on monocyte adhesion and osteoclastic differentiation.

CONCLUSIONS

Heat pre-treatment of hPDL cells induces cell-protective mechanisms towards mechanical stress and favors the reduction of cell stress associated effects on monocyte/macrophage physiology.

CLINICAL RELEVANCE

These data present the induction of heat shock proteins as a promising treatment option to limit undesired side effects of periodontal remodeling.

The oxidation of HSP70 is associated with functional impairment and lack of stimulatory capacity

Expression of intracellular HSP70 is associated with cytoprotective effects against a wide range of stressful stimuli, such as inflammation, oxidative stress, hypoxia, endotoxins, infections, and fever. This cytoprotective effect is mainly attributed to their ability to stabilize protein structures through chaperone-like reversible interactions. HSP70 was recently detected in the extracellular medium, and its presence in serum is commonly associated with pathological situations, where it exerts modulatory effects on cells of the immune system. Previously, we have described the relationship between serum HSP70 levels, oxidant status, and clinical outcome of septic patients; the group of patients with higher prooxidant status and higher serum HSP70 had also higher mortality. To investigate the possible association between oxidized HSP70 and cytoprotection or cell death, we incubated RAW 264.7 macrophages with oxidized HSP70 and evaluated nitrite production, cell proliferation, cell viability, TNF-α release, and phagocytic activity. We also evaluated structural modifications caused by oxidation in purified HSP70. Oxidation of HSP70 altered its protein structure; besides, the modulatory effect of oxidized HSP70 on RAW264.7 cells was different from that of native HSP70. Macrophages treated with oxidized HSP70 presented lower proliferation and viability, lower phagocytic activity, and lower TNF-α release. These results indicate that oxidation of extracellular HSP70 modified its signaling properties, causing alterations on its modulatory effects on macrophage function and viability.

Role of heat shock proteins in oxygen radical-induced gastric apoptosis

BACKGROUND

The generation of reactive oxygen species (ROS) and their resultant oxidative damage is a common pathway for gastric mucosal injury. Developing strategies to protect the gastric epithelium against oxygen free radical damage is of profound pathophysiological interest. We have previously shown caspase-mediated apoptosis as a major cause of ROS-induced cell death in gastric mucosa. Because heat shock proteins (Hsps) confer protection against many cytotoxic agents, this study was undertaken to determine whether modulation of Hsps was protective against oxidative damage.

MATERIALS AND METHODS

AGS cells (human gastric mucosal cell line) received either no pretreatment, heat shock pretreatment (1 h at 42 ± 1°C), or pretreatment with an Hsp modulating drug (geldanamycin or quercetin). Cells were then exposed to hydrogen peroxide (H2O2), a representative ROS (1 mM, a physiologically relevant concentration), for 24 h. Caspase-3 activation and Poly ADP Ribose Polymerase (PARP) inactivation, as well as DNA-histone complex formation were used as measures of apoptosis. Inducible Hsps (Hsp70 and Hsp90) were detected using Western blot analysis.

RESULTS

Results showed heat shock pretreatment induced increased expression of Hsp70 without change in Hsp90. In response to H2O2 exposure alone, there was significant increase in DNA-histone complex formation as well as caspase-3 activation and PARP cleavage in gastric epithelium. Heat shock pretreatment resulted in statistically significant prevention in these measures of apoptosis. Geldanamycin increased Hsp70, but elicited cleavage of Hsp90 and subsequently resulted in an increase in H2O2-induced apoptosis. Quercetin decreased Hsp70 and resulted again in increased H2O2-induced apoptosis.

CONCLUSIONS

These findings indicate that heat shock pretreatment protects gastric mucosal cells against H2O2-induced apoptosis and that Hsp70 and Hsp90 may play key roles in this process. These results further suggest that perturbations in Hsp metabolism may induce mucosal injury in response to oxygen free radicals.

Heat shock protein 72 expressing stress in sepsis: unbridgeable gap between animal and human studies--a hypothetical "comparative" study

Heat shock protein 72 (Hsp72) exhibits a protective role during times of increased risk of pathogenic challenge and/or tissue damage. The aim of the study was to ascertain Hsp72 protective effect differences between animal and human studies in sepsis using a hypothetical “comparative study” model. Forty-one in vivo (56.1%), in vitro (17.1%), or combined (26.8%) animal and 14 in vivo (2) or in vitro (12) human Hsp72 studies (P < 0.0001) were enrolled in the analysis. Of the 14 human studies, 50% showed a protective Hsp72 effect compared to 95.8% protection shown in septic animal studies (P < 0.0001). Only human studies reported Hsp72-associated mortality (21.4%) or infection (7.1%) or reported results (14.3%) to be nonprotective (P < 0.001). In animal models, any Hsp72 induction method tried increased intracellular Hsp72 (100%), compared to 57.1% of human studies (P < 0.02), reduced proinflammatory cytokines (28/29), and enhanced survival (18/18). Animal studies show a clear Hsp72 protective effect in sepsis. Human studies are inconclusive, showing either protection or a possible relation to mortality and infections. This might be due to the fact that using evermore purified target cell populations in animal models, a lot of clinical information regarding the net response that occurs in sepsis is missing.

Treadmill exercise preconditioning attenuates lung damage caused by systemic endotoxemia in type 1 diabetic rats

Endotoxemia induces a series of inflammatory responses that may result in lung injury. However, heat shock protein72 (HSP72) has the potential to protect the lungs from damage. The objective of this study was to determine whether prior exercise conditioning could increase the expression of HSP72 in the lungs and attenuate lung damage in diabetic rats receiving lipopolysaccharide (LPS). Streptozotocin was used to induce diabetes in adult male Wistar rats. Rats were randomly assigned to sedentary or exercise groups. Rats in the exercise condition ran on a treadmill 5 days/week, 30-60 min/day, with an intensity of 1.0 mile/hour over a 3-week period. Rats received an intravenous infusion of LPS after 24 hrs from the last training session. Elevated lavage tumor necrosis factor-alpha (TNF- α ) level in response to LPS was more marked in diabetic rats. HSP72 expression in lungs was significantly increased after exercise conditioning, but less pronounced in diabetic rats. After administration of LPS, exercised rats displayed higher survival rate as well as decreased lavage TNF- α level and lung edema in comparison to sedentary rats. Our findings suggest that exercise conditioning could attenuate the occurrence of inflammatory responses and lung damage, thereby reducing mortality rate in diabetic rats during endotoxemia.

Heat shock protein 70, oxidative stress, and antioxidant status in periparturient crossbred cows supplemented with α-tocopherol acetate

The study was conducted to investigating the effect of α-tocopherol acetate on heat shock protein 70 (Hsp70), oxidative stress, and antioxidant status during periparturient period in medium body condition score crossbred cows. Twenty crossbred Karan Fries cows with confirmed pregnancy were selected 2 months before expected date of calving. The cows were randomly distributed in to two groups: 10 cows were kept as control and 10 were supplemented with α-tocopherol acetate during dry period for 2 months. Blood samples were collected at -20, -10, -5, 0, 5, 10, and 20 days in relation to the expected date of calving. Superoxide dismutase, catalase, and total immunoglobulin were significantly higher (P < 0.01) in treatment as compared to control cows. Heat shock protein 70 and thiobarbituric acid reactive substance levels were significantly lower (P < 0.01) in the treatment cows than their counterpart. Treatment with α-tocopherol acetate during dry period resulted in reduced oxidative stress, heat shock protein Hsp70 levels, improved antioxidant, and improved immunity status indicating beneficial effect of α-tocopherol acetate treatment.

Exercise regulates heat shock proteins and nitric oxide

Heat shock proteins (HSP) produced during exercise have important roles in modulating the effects of oxidative stresses to preserve cellular function. The ability of HSP to regulate nitric oxide, which has both protective and detrimental effects on the airways and circulation, may have implications for exercise-induced asthma. Exercise regulates HSP and nitric oxide interactions and protects against organ dysfunction and oxidative stresses.

Fluoro-edenite fibers induce expression of Hsp70 and inflammatory response

Many asbestos-like mineral fibers have been detected in the air of mountainous and volcanic areas of Italy and other parts of the world. These fibers have been suspected to be the cause of increased incidences of lung cancer and other lung diseases in these areas. However, the mechanisms of the cellular response and defense following exposure to these microscopic fibers have not been characterized. We continue to study these mechanisms to be able to propose preventive strategies in large populations. The objective of the present study was to determine comparatively biological responses of mesothelial Met-5A and monocyte-macrophage J774 cells following exposure to two types of fluoro-edenite fibers having low and high iron content (labeled 19 and 27, respectively) obtained from Biancavilla (Sicily, Italy). The reference fiber was a non-iron fibrous tremolite from Val di Susa (Piemonte, Italy). The cells were treated with 5, 50, and 100 μg of fibrous matter per 1 ml for 72 hr. We identified several key mechanisms by which cells responded and counteracted the injury induced by these fibers. The fibers caused induction of the heat shock protein 70 (Hsp70), stimulated formation of reactive oxygen species (detected by using DCFH-DA as a fluorescent probe) and NO^• (measured as nitrite). Exposure of cells to the fibers induced lactate dehydrogenase activity and decreased viability. The fluoro-endenite type 27 was the most potent fiber tested, which indicated that iron and possibly manganese contribute significantly to this fiber toxicity. The J774 cells were more sensitive to fluoro-edenite than Met-5A cells suggesting that the primary site of the fiber-induced inflammatory response could be the macrophage rather than the pulmonary epithelium. Fluoro-edenite produces more biological alterations with respect to non-iron tremolite. Hsp70 and free radicals could be important factors in the context of mineral fiber-induced acute lung injury leading possibly to mutagenic effects. We anticipate that pharmacological blockade of the fiber-dependent cellular responses could in long term offer preventive approach to combat lung diseases induced by these fibers.

Heat shock response and acute lung injury

All cells respond to stress through the activation of primitive, evolutionarily conserved genetic programs that maintain homeostasis and assure cell survival. Stress adaptation, which is known in the literature by a myriad of terms, including tolerance, desensitization, conditioning, and reprogramming, is a common paradigm found throughout nature, in which a primary exposure of a cell or organism to a stressful stimulus (e.g., heat) results in an adaptive response by which a second exposure to the same stimulus produces a minimal response. More interesting is the phenomenon of cross-tolerance, by which a primary exposure to a stressful stimulus results in an adaptive response whereby the cell or organism is resistant to a subsequent stress that is different from the initial stress (i.e., exposure to heat stress leading to resistance to oxidant stress). The heat shock response is one of the more commonly described examples of stress adaptation and is characterized by the rapid expression of a unique group of proteins collectively known as heat shock proteins (also commonly referred to as stress proteins). The expression of heat shock proteins is well described in both whole lungs and in specific lung cells from a variety of species and in response to a variety of stressors. More importantly, in vitro data, as well as data from various animal models of acute lung injury, demonstrate that heat shock proteins, especially Hsp27, Hsp32, Hsp60, and Hsp70 have an important cytoprotective role during lung inflammation and injury.

Expression of heat-shock protein 70 (Hsp70) in the respiratory tract and lungs of fire victims

Immunohistochemical investigation of the respiratory tract and lungs of 63 fire victims revealed a statistically significant enhanced expression of heat-shock protein 70 (Hsp70) in the epiglottis, the trachea, and the main and the peripheral bronchi compared with a control group. In the fire victims, a strong expression of Hsp70 was discernible not only particularly in the vessels but also in seromucous secretory cells, ciliated epithelial cells, smooth muscle cells, and alveolar cells. The results suggest a vital or supravital reaction due to the inhalation of hot fire fumes.

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.

New insights on brain stem death: From bedside to bench

As much as brain stem death is currently the clinical definition of death in many countries and is a phenomenon of paramount medical importance, there is a dearth of information on its mechanistic underpinnings. A majority of the clinical studies are concerned only with methods to determine brain stem death. Whereas a vast amount of information is available on the cellular and molecular mechanisms of cell death, rarely are these studies directed specifically towards the understanding of brain stem death. This review presents a framework for translational research on brain stem death that is based on systematically coordinated clinical and laboratory efforts that center on this phenomenon. It begins with the identification of a novel clinical marker from patients that is related specifically to brain stem death. After realizing that this "life-and-death" signal is related to the functional integrity of the brain stem, its origin is traced to the rostral ventrolateral medulla (RVLM). Subsequent laboratory studies on this neural substrate in animal models of brain stem death provide credence to the notion that both "pro-life" and "pro-death" programs are at work during the progression towards death. Those programs (mitochondrial functions, nitric oxide, peroxynitrite, superoxide anion, coenzyme Q10, heat shock proteins and ubiquitin-proteasome system) hitherto identified from the RVLM are presented, along with their cellular and molecular mechanisms. It is proposed that outcome of the interplay between the "pro-life" and "pro-death" programs (dying) in this neural substrate determines the final fate of the individual (being dead). Thus, identification of additional programs in the RVLM and delineation of their regulatory mechanisms should shed new lights on future directions for clinical management of life-and-death.

Missing effects of zinc in a porcine model of recurrent endotoxemia

Background

Chronic human sepsis often is characterised by the compensatory anti-inflammatory response syndrome (CARS). During CARS, anti-inflammatory cytokines depress the inflammatory response leading to secondary and opportunistic infections. Proved in vitro as well as in vivo, zinc's pro-inflammatory effect might overcome this depression.

Methods

We used the model of porcine LPS-induced endotoxemia established by Klosterhalfen et al. 10 pigs were divided into two groups (n = 5). Endotoxemia was induced by recurrent intravenous LPS-application (1.0 μg/kg E. coli WO 111:B4) at hours 0, 5, and 12. At hour 10, each group received an intravenous treatment (group I = saline, group II = 5.0 mg/kg elementary zinc). Monitoring included hemodynamics, blood gas analysis, and the thermal dilution technique for the measurement of extravascular lung water and intrapulmonary shunt. Plasma concentrations of IL-6 and TNF-alpha were measured by ELISA. Morphology included weight of the lungs, width of the alveolar septae, and rate of paracentral liver necrosis.

Results

Zinc's application only trended to partly improve the pulmonary function. Compared to saline, significant differences were very rare. IL-6 and TNF-alpha were predominately measured higher in the zinc group. Again, significance was only reached sporadically. Hemodynamics and morphology revealed no significant differences at all.

Conclusion

The application of zinc in this model of recurrent endotoxemia is feasible and without harmful effects. However, a protection or restoration of clinical relevance is not evident in our setting. The pulmonary function just trends to improve, cytokine liberation is only partly activated, hemodynamics and morphology were not influenced. Further pre-clinical studies have to define zinc's role as a therapeutic tool during CARS.

Stress-Induced Inhibition of the NF-κB Signaling Pathway Results from the Insolubilization of the IκB Kinase Complex following Its Dissociation from Heat Shock Protein 90

Activation of the stress response attenuates proinflammatory responses by suppressing cytokine-stimulated activation of the NF-kappaB signaling pathway. In this study, we show that the activation of the cellular stress response, either by heat shock treatment or after exposure to sodium arsenite, leads to a transient inhibition of IkappaBalpha phosphorylation. Inhibition of IkappaBalpha phosphorylation after stress was associated with the detergent insolubilization of the upstream kinases, IkappaB kinase alpha (IKKalpha) and IkappaB kinase beta, components involved in IkappaBalpha phosphorylation. Pretreatment of cells with glycerol, a chemical chaperone that reduces the extent of stress-induced protein denaturation, reduced the stress-dependent detergent insolubility of the IKK complex and restored the cytokine-stimulated phosphorylation of IkappaB. The stress-dependent insolubility of the IKK complex appeared reversible; as the cells recovered from the heat shock treatment, the IKK complex reappeared within the soluble fraction of cells and was again capable of mediating the phosphorylation of IkappaBalpha in response to added cytokines. Treatment of cells with geldanamycin, an inhibitor of heat shock protein 90 (Hsp90) function, also resulted in IKK detergent insolubility and proteasome-mediated degradation of the IKK complex. Furthermore, while IKKalpha coprecipitated with Hsp90 in control cells, coprecipitation of the two proteins was greatly reduced in those cells early after stress or following exposure to geldanamycin. Stress-induced transient insolubilization of the IkappaB kinase complex following its dissociation from Hsp90 represents a novel mechanism by which the activation of the stress response inhibits the NF-kappaB signaling pathway in response to proinflammatory stimuli.

Protective effect of heat shock protein 70 against oxidative stresses in human corneal fibroblasts

We evaluated DNA protection effect of heat shock protein (HSP) against cytotoxic effects of exogenous nitric oxide (NO) and reactive oxygen intermediate (ROI). Cultured human corneal fibroblasts were divided into 4 groups. Control (Group I) was not exposed to a sub-lethal heat treatment. Other 3 groups were exposed to 43 degrees C for 1 hr, then incubated at 37 degrees C during different duration (1, 6, 24 hr, Group II, III, IV, respectively). Expression pattern of HSP 70 was analyzed by Western blot. Cell viability was measured by MTT assay and the relationship between HSP 70 expression and DNA damage was examined by terminal deoxyribonucleotidyl transferase mediated dUTP-digoxigenin nick and labeling (TUNEL) stain and single cell gel electrophoresis. Expression pattern of HSP 70 was dependent on recovery times. Cell viability following heat treatment was significantly increased and the TUNEL positive cell number was decreased at 6 hr. In single cell gel electrophoresis, tail moments were increased in a dose-dependent manner by SNAP and X/XO. Following heat treatment, tail moments showed decreased significantly at 6 hr. These results suggest that induction of HSP 70 by sub-lethal heat treatment is closely related with cytoprotective effects against oxidative stresses in human corneal fibroblasts.

Geldanamycin treatment inhibits hemorrhage-induced increases in KLF6 and iNOS expression in unresuscitated mouse organs: role of inducible HSP70

The aim of this study was to determine whether hemorrhage affects the levels of a variety of stress-related proteins and whether changes can be inhibited by drugs reported to provide protection from ischemia and reperfusion injury. Male Swiss Webster mice were subjected to a 40% hemorrhage without resuscitation. Western blot analysis indicated that c-Jun (an AP-1 protein), Kruppel-like factor 6 (KFL6), and inducible nitric oxide synthase (iNOS) were upregulated sequentially in that order. Pretreatment of mice with geldanamycin (GA) 16 h before hemorrhage effectively inhibited the expression of the proteins KLF6 and iNOS, whereas caffeic acid phenethyl ester did not. GA pretreatment increased inducible heat shock protein (HSP) 70 but not HSP90 in both sham and hemorrhagic tissues. The overexpressed inducible HSP70 formed complexes with KLF6 and iNOS. These results suggest that GA may be therapeutically useful for reducing hemorrhage-induced injury when used as a presurgical treatment or when added to resuscitation fluids.

Expressional pattern of chaperones in neuronal, glial, amnion, mesothelial, and bronchial epithelial cell lines

Although literature is abundant on expression of individual heat shock proteins (HSPs) and molecular chaperones, no comprehensive information is given on their expressional pattern. The aim of our study was therefore to study expressional differences between several cell types that may provide evidence for the types of HSPs and chaperones that may be operating in the corresponding lineages. For this purpose neuronal (HCN-2), glial (SVG-p12), amnion, mesothelial (Met-5A), and bronchial epithelial (16HBE14o(-)) cell lines were grown, harvested, and protein was separated on two-dimensional electrophoresis with subsequent in-gel digestion and identification of protein spots by MALDI-MS and specific software. A series of 29 high abundance HSPs and chaperones were unambiguously identified altogether. We observed distinct expressional patterns and although overlapping, there was an apparent paucity of HSPs and chaperones in bronchial epithelial and mesothelial cells. We learn from this study that individual cell lines express and may use different HSP and chaperones systems and strategies. Specific functions of cells may be responsible as well as the presence of protein specific chaperones, although we cannot rule out that cell culture conditions were at least in part responsible for the different expressional patterns.

Intracellular delivery of HSP70 using HIV-1 Tat protein transduction domain

Heat shock protein 70 (HSP70) is an intracellular stress protein that confers cytoprotection to a variety of cellular stressors. Several lines of evidence have suggested that augmentation of the heat shock response by increasing the expression of HSP70 represents a potential therapeutic strategy for the treatment of critically ill patients. The Tat protein of human immunodeficiency virus 1 (HIV-1) has been used previously to deliver functional cargo proteins intracellularly when added exogenously to cultured cells. We generated a Tat-HSP70 fusion protein using recombinant methods and treated HSF -/- cells with either Tat-HSP70 or recombinant HSP70 prior to exposure to hyperoxia or lethal heat shock. We showed that biologically active, exogenous HSP70 can be delivered into cells using the HIV-1 Tat protein, and that the Tat-mediated delivery of HSP70 confers cytoprotection against thermal stress and hyperoxia and may represent a novel approach to augmenting intracellular HSP70 levels.

A DNA microarray study of nitric oxide-induced genes in mouse hepatocytes: implications for hepatic heme oxygenase-1 expression in ischemia/reperfusion

Nitric oxide (NO) can modulate numerous genes directly; however, some genes may be modulated only in the presence of the inflammatory stimuli that increase the expression of the inducible nitric oxide synthase (iNOS). One method by which to examine changes in NO-mediated gene expression is to carry out a gene array analysis on NO-nai;ve cells. Herein, we report a gene array analysis on mRNA from iNOS-null (iNOS(-/-)) mouse hepatocytes harvested from mice exposed to NO by infection with an adenovirus expressing human iNOS (Ad-iNOS). Of the 6500 genes on this array, only approximately 200 were modulated either up or down by the increased iNOS activity according to our criteria for significance. Several clearly defined families of genes were modulated, including genes coding for proinflammatory transcription factors, cytokines, cytokine receptors, proteins associated with cell proliferation and cellular energetics, as well as proteins involved in apoptosis. Our results suggest that iNOS has a generally anti-inflammatory and anti-apoptotic role in hepatocytes but also acts to suppress proliferation and protein synthesis. The expression of iNOS results in increased expression of stress-related proteins, including heme oxygenase-1 (HO-1). We used HO-1 to confirm that a significant change identified by an analysis could be demonstrated as significant in cells and tissues. The elevation of HO-1 was confirmed at the protein level in hepatocytes in vitro. Furthermore, iNOS(-/-) mice experienced greatly increased liver injury subsequent to intestinal ischemia/reperfusion injury, associated with an inability to upregulate HO-1. This is the first study to address the global gene changes induced by iNOS in any cell type, and the findings presented herein may have clinical relevance for conditions such as septic or hemorrhagic shock in which hepatocytes, NO, and HO-1 play a crucial role.

Adenoviral transfer of HSP-70 into pulmonary epithelium ameliorates experimental acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) provokes three pathologic processes: unchecked inflammation, interstitial/alveolar protein accumulation, and destruction of pulmonary epithelial cells. The highly conserved heat shock protein HSP-70 can limit all three responses but is not appropriately expressed in the lungs after cecal ligation and double puncture (2CLP), a clinically relevant model of ARDS. We hypothesize that restoring expression of HSP-70 using adenovirus-mediated gene therapy will limit pulmonary pathology following 2CLP. We administered a vector containing the porcine HSP-70 cDNA driven by a CMV promoter (AdHSP) into the lungs of rats subjected to 2CLP or sham operation. Administration of AdHSP after either sham operation or 2CLP increased HSP-70 protein expression in lung tissue, as determined by immunohistochemistry and Western blot hybridization. Administration of AdHSP significantly attenuated interstitial and alveolar edema and protein exudation and dramatically decreased neutrophil accumulation, relative to a control adenovirus. CLP-associated mortality at 48 hours was reduced by half. Modulation of HSP-70 production reduces pathologic changes and may improve outcome in experimental ARDS.

Adenoviral transfer of HSP-70 into pulmonary epithelium ameliorates experimental acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) provokes three pathologic processes: unchecked inflammation, interstitial/alveolar protein accumulation, and destruction of pulmonary epithelial cells. The highly conserved heat shock protein HSP-70 can limit all three responses but is not appropriately expressed in the lungs after cecal ligation and double puncture (2CLP), a clinically relevant model of ARDS. We hypothesize that restoring expression of HSP-70 using adenovirus-mediated gene therapy will limit pulmonary pathology following 2CLP. We administered a vector containing the porcine HSP-70 cDNA driven by a CMV promoter (AdHSP) into the lungs of rats subjected to 2CLP or sham operation. Administration of AdHSP after either sham operation or 2CLP increased HSP-70 protein expression in lung tissue, as determined by immunohistochemistry and Western blot hybridization. Administration of AdHSP significantly attenuated interstitial and alveolar edema and protein exudation and dramatically decreased neutrophil accumulation, relative to a control adenovirus. CLP-associated mortality at 48 hours was reduced by half. Modulation of HSP-70 production reduces pathologic changes and may improve outcome in experimental ARDS.

Stress preconditioning attenuates oxidative injury to the alveolar epithelium of the lung following haemorrhage in rats

Inhibition of cAMP-dependent stimulation of vectorial fluid transport across the alveolar epithelium following haemorrhagic shock is mediated by reactive nitrogen species released within the airspaces of the lung. We tested here the hypothesis that the prior activation of the cellular heat shock or stress response, via exposure to either heat or geldanamycin, would attenuate the release of airspace nitric oxide (NO) responsible for the shock-mediated failure of the alveolar epithelium to respond to catecholamines in rats. Rats were haemorrhaged to a mean arterial pressure of 30-35 mmHg for 60 min, and then resuscitated with a 4 % albumin solution. Alveolar fluid clearance was measured by change in concentration of a protein solution instilled into the airspaces 5 h after the onset of haemorrhage. Stress preconditioning restored the cAMP-mediated upregulation of alveolar liquid clearance after haemorrhage. The protective effect of stress preconditioning was mediated in part by a decrease in the expression of iNOS in the lung. Specifically, stress preconditioning decreased the production of nitrite by endotoxin-stimulated alveolar macrophages removed from haemorrhaged rats or by A549 and rat alveolar epithelial type II cell monolayers stimulated with cytomix (a mixture of TNF-alpha, IL-1beta and IFN-gamma) for 24 h. In summary, these results provide the first in vivo evidence that stress preconditioning restores a normal fluid transport capacity of the alveolar epithelium in the early phase following haemorrhagic shock by attenuating NO-mediated oxidative stress to the lung epithelium.

ARDS. The future

Improving the course and outcome of patients with ARDS presents a considerable challenge. An important component of meeting this challenge is a more comprehensive understanding of the heterogeneous pathophysiology of ARDS and the biologic response of the individual patient. This understanding may be developed through the power of genomics and its related technology. In particular, it will be crucial to characterize the immunophenotypes of individual patients with ARDS. By understanding the immune status of a given patient at a given point in the disease process, physicians can consider manipulating proinflammatory systems more rationally, such as the complement and chemokine cascades, or the anti-inflammatory arm of the immune system. Finally, a more refined molecular and genetic understanding of endogenous cytoprotective molecules and mechanisms, such as the heat shock response and HO-1, may provide further tools in the future armamentarium against ARDS.

Effects of heat shock protein 70 (Hsp70) on arsenite-induced genotoxicity

Arsenic, a human carcinogen, is genotoxic, although its mechanism(s) of action for tumorigenesis is not well understood. Among the toxicity-related properties of this chemical are its clastogenic and aneugenic activities, as well as its capacity for inducing stress-response in the form of elevated heat shock protein (HSP) expression. In the present study, we evaluated the effects of Hsp70 expression on arsenite (As)-induced structural and numerical chromosome anomalies in human cells. Human MCF-7 Tet-off cells stably transfected with a pTRE/Hsp70-1 transgene construct were used to regulate Hsp70 levels prior to in vitro As exposures. Separate cultures of relatively high vs. low Hsp70-expressing cells were established. A cytokinesis block micronucleus assay with kinetochore immunostaining was used to detect micronuclei (MN) derived from chromosome breakage (K-MN) or loss (K+MN). These studies demonstrated significant increases in micronucleus frequencies in response to As following either a long exposure (5 or 10 microM for 46 hr), or short exposure (10 or 40 microM for 8 hr) protocol. Overall, the long protocol was more efficient in producing K+MN and cells with multiple MN. Overexpressing Hsp70 resulted in significant reductions in the percent of cells positive for MN for both the long and short As exposure protocols. Both K+ and K- types of As-induced MN were lower in cells with elevated Hsp70 as compared to cells without overexpression of Hsp70. We conclude that the dose and duration of As exposure influence the type as well as amount of chromosomal alteration produced and that inducible Hsp70 protects against both the clastogenic and aneugenic effects of this chemical.

The impact of molecular biology on the practice of pediatric critical care medicine

Molecular biology is increasingly affecting all areas of clinical medicine, including pediatric critical care medicine. Recent advances in genomics will allow for a more in-depth understanding of disease processes that are relevant to the pediatric intensivist, such as sepsis, the acute respiratory distress syndrome, and multiple organ dysfunction syndrome. In turn, understanding critical illness at the genomic level may allow for more effective stratification of patient subclasses and targeted, patient-specific therapy. The related fields of pharmacogenomics and pharmacogenetics hold the promise of improved drug development and the tailoring of drug therapy based on the individual's drug metabolism profile. Therapeutic strategies aimed at modulating host inflammatory responses remain viable but will need to take into account the inherent redundancy of the host inflammatory response and the heterogenous responses between individual patients. Thus, "immuno-phenotyping" of critically ill patients will allow for more rational immune-modulating therapies, either in the form of inhibiting or enhancing specific immune/inflammatory responses. The host also contains powerful, broad cytoprotective mechanisms that could potentially be harnessed as a strategy for organ and tissue protection in many forms of critical illness. Finally, prospects for gene therapy, although quite challenging at present, may be applicable to the intensive care unit in the near future. With these rapid advancements in molecular biology, it is imperative that all pediatric critical care practitioners become, at least, familiar with the field and its related technology. Hopefully, clinician-scientists involved in pediatric critical care will also shape the direction of these future prospects.

Attenuation of sepsis-induced apoptosis by heat shock pretreatment in rats

Apoptosis is a process by which cells undergo a form of non-necrotic cellular suicide. Although it is a programmed process, apoptosis can be induced by various stressors. During sepsis, apoptosis has been regarded as an important cause of cell death in the immune system, leading to unresponsiveness to treatment. This study was designed to investigate how prior heat shock induction can influence the rate of apoptosis in animals that have experienced sepsis. Sprague-Dawley rats were used, and experimental sepsis was induced by cecal ligation and puncture (CLP). Animals in the heated group were anesthetized and received heat shock by whole-body hyperthermia. They were sacrificed 9 h and 18 h after CLP as early and late sepsis, respectively. Apoptosis was evaluated by "DNA ladder" detection in agarose electrophoresis and Tdt-mediated dUTP nick end-labeling (TUNEL) assay. Hsp72 was detected by Western blot analysis. The results showed that the DNA ladder was detected most clearly in the thymus at the late phase of sepsis with time course dependence, while it showed less clearly in heat shock treated animals. Histopathological study by TUNEL assay obtained similar results in the thymus, where the cortex was more susceptible to apoptosis than the medulla. The Western blot analysis showed that the heat shock induced Hsp72 concomitant with an increase in Bcl-2:Bax ratio. In conclusion, heat shock pretreatment prevents rats from sepsis-induced apoptosis that may account for the better outcome of experimental sepsis. An increase in the Bcl-2:Bax ratio may in part explain the molecular mechanism of the effect of heat shock pretreatment.

An electrophoretic study of vitamin E status and expression of heat shock proteins in alveolar type II and liver cells

Vitamin E is the most important lipophilic antioxidant. Oxidative injuries are prevented or minimized by vitamin E supplementation. Various physiological and pathological situations are accompanied by vitamin E deficiency. However, it is not clear whether alimentary vitamin E deficiency in itself constitutes oxidant stress that induces appropriate responses, which, in turn, can be avoided by adequate vitamin E supplies, or whether the remaining cellular antioxidants compensate a temporary vitamin E deficiency. We studied effects of the dietary vitamin E status on cellular vitamin E levels and on the expression of heat shock proteins (HSPs) in alveolar type II cells and liver. The expression of HSPs, representing an early and very sensitive marker of cellular stress, was compared with the activity of antioxidative enzymes. Vitamin E depletion caused a substantial increase in HSP32 in alveolar type II cells, whereas in liver there was a marked increase in HSP70. The activity of the antioxidant enzymes, however, did not change significantly. A reversal of HSP expression to almost normal levels was seen after vitamin E resupplementation. These results indicate that, under normal conditions, a suboptimal supply of vitamin E to rats exposes the alveolar type II cells and the liver to reversible cellular stress.

Effect of hypoxia on DNA fragmentation in different brain regions of the newborn piglet

DNA fragmentation has been studied in different regions of the newborn piglet brain following different times of normobaric hypoxia (5% O(2), 95% N(2)). After 1 hr of hypoxia, fragmented DNA was observed in cerebellum, cortex, hippocampus, and striatum but not in hypothalamus. More fragmentation occurred in these areas of the brain when the animals were kept under hypoxia for times up to 8 hr 45 min. When the animals were submitted to hypoxia for two and a half hours, integrity of DNA was recovered respectively after 3 hr of exposure to the ambient atmosphere in hippocampus and striatum, but 4 hr of recovery were necessary for cerebellum and cortex. These results are discussed in terms of the consequences of neonatal hypoxia and apnea for newborn infants and economical impact for farm animals.

Attenuation of sepsis-induced apoptosis by heat shock pretreatment in rats

Apoptosis is a process by which cells undergo a form of non-necrotic cellular suicide. Although it is a programmed process, apoptosis can be induced by various stressors. During sepsis, apoptosis has been regarded as an important cause of cell death in the immune system, leading to unresponsiveness to treatment. This study was designed to investigate how prior heat shock induction can influence the rate of apoptosis in animals that have experienced sepsis. Sprague-Dawley rats were used, and experimental sepsis was induced by cecal ligation and puncture (CLP). Animals in the heated group were anesthetized and received heat shock by whole-body hyperthermia. They were sacrificed 9 h and 18 h after CLP as early and late sepsis, respectively. Apoptosis was evaluated by "DNA ladder" detection in agarose electrophoresis and Tdt-mediated dUTP nick end-labeling (TUNEL) assay. Hsp72 was detected by Western blot analysis. The results showed that the DNA ladder was detected most clearly in the thymus at the late phase of sepsis with time course dependence, while it showed less clearly in heat shock treated animals. Histopathological study by TUNEL assay obtained similar results in the thymus, where the cortex was more susceptible to apoptosis than the medulla. The Western blot analysis showed that the heat shock induced Hsp72 concomitant with an increase in Bcl-2:Bax ratio. In conclusion, heat shock pretreatment prevents rats from sepsis-induced apoptosis that may account for the better outcome of experimental sepsis. An increase in the Bcl-2:Bax ratio may in part explain the molecular mechanism of the effect of heat shock pretreatment.

Anti-inflammatory effect of heat shock protein induction is related to stabilization of I kappa B alpha through preventing I kappa B kinase activation in respiratory epithelial cells

Heat shock protein (HSP) induction confers protection against diverse forms of cellular and tissue injury. However, the mechanism by which HSP exerts cytoprotective effects is unclear. Because HSP induction inhibits genetic expression of pro-inflammatory cytokines, the transcription of which is dependent on NF-kappa B activation, we explored the relationship between the anti-inflammatory effect of HSP induction and the NF-kappa B/I kappa B alpha pathway. Both HS and sodium arsenite treatment increased HSP70 expression time dependently at mRNA and protein levels. Prior induction of HSP suppressed cytokine-induced IL-8 and TNF-alpha expression at both mRNA and protein levels. Although HSP induction did not affect total cellular expression of NF-kappa B, TNF-alpha-induced increase in NF-kappa B-DNA binding activity and nuclear translocation of the p65 subunit of NF-kappa B were inhibited by prior HSP induction, suggesting that activation of NF-kappa B was blocked. Cytokine-induced I kappa B alpha phosphorylation and its degradation were blocked in HSP-induced cells. Immune complex kinase assays demonstrated that TNF-alpha induced increase in I kappa B kinase activity was suppressed by prior HSP induction. These results suggest that the anti-inflammatory effect of HSP induction in respiratory epithelial cells is related to stabilization of I kappa B alpha, possibly through the prevention of I kappa B kinase activation, which thereby inhibits activation of NF-kappa B.

Increased expression of heat shock protein-70 protects A549 cells against hyperoxia

Acute and chronic lung injury secondary to hyperoxia remains an important complication in critically ill patients, and, consequently, there is interest in developing strategies to protect the lung against hyperoxia. Heat shock proteins (HSPs) confer protection against a broad array of cytotoxic agents. In this study, we tested the hypothesis that increased expression of the 70-kDa HSP (HSP70) would protect cultured human respiratory epithelium against hyperoxia. Recombinant A549 cells were generated in which human HSP70 was increased by stable transfection with a plasmid containing human HSP70 cDNA under control of the cytomegalovirus promoter (A549-HSP70 cells). A549-HSP70 cells exposed to hyperoxia had greater acute survival rates and clonogenic capacity compared with wild-type A549 cells and with control cells stably transfected with the empty expression plasmid. Hyperoxia-mediated lipid peroxidation and ATP depletion were also attenuated in A549-HSP70 cells exposed to hyperoxia. Increased expression of HSP70 did not detectably alter mRNA levels of the intracellular antioxidants manganese superoxide dismutase, catalase, and glutathione peroxidase. Collectively, these data demonstrate a specific in vitro protective role for HSP70 against hyperoxia and suggest that potential mechanisms of protection involve attenuation of hyperoxia-mediated lipid peroxidation and ATP depletion.

The Heat Shock Response Inhibits RANTES Gene Expression in Cultured Human Lung Epithelium

The chemokine RANTES is thought to be involved in the pathophysiology of inflammation-associated acute lung injury. Although much is known regarding signals that induce RANTES gene expression, relatively few data exist regarding signals that inhibit RANTES gene expression. The heat shock response, a highly conserved cellular defense mechanism, has been demonstrated to inhibit a variety of lung proinflammatory responses. We tested the hypothesis that induction of the heat shock response inhibits RANTES gene expression. Treatment of A549 cells with TNF-α induced RANTES gene expression in a concentration-dependent manner. Induction of the heat shock response inhibited subsequent TNF-α-mediated RANTES mRNA expression and secretion of immunoreactive RANTES. Transient transfection assays involving a RANTES promoter-luciferase reporter plasmid demonstrated that the heat shock response inhibited TNF-α-mediated activation of the RANTES promoter. Inhibition of NF-κB nuclear translocation with isohelenin inhibited TNF-α-mediated RANTES mRNA expression, indicating that RANTES gene expression is NF-κB dependent in A549 cells. Induction of the heat shock response inhibited degradation of the NF-κB inhibitory protein, I-κBα but did not significantly inhibit phosphorylation of I-κBα. We conclude that the heat shock response inhibits RANTES gene expression by a mechanism involving inhibition of NF-κB nuclear translocation and subsequent inhibition of RANTES promoter activation. The mechanism by which the heat shock response inhibits NF-κB nuclear translocation involves stabilization of I-κBα, without significantly affecting phosphorylation of I-κBα.