Heat shock protein 70 expression in neonatal rats after hypoxic stress

Forensic application of epidermal expression of HSP27 and HSP70 for the determination of wound vitality in human compressed neck skin

Estimating the age and vitality of human skin wounds is essential in forensic practice, and the use of immunohistochemical parameters in this regard remains a challenge. Heat shock proteins (HSPs) are evolutionarily conserved universal proteins that protect biological systems from various types of stress. However, its importance in forensic pathology for determining wound activation in neck compression skin remains unclear. The expression of HSP27 and HSP70 in neck skin samples was immunohistochemically examined to understand its forensic applicability in determining wound vitality. Skin samples were obtained from 45 cases of neck compression (hanging, 32 cases; strangulation, 10 cases; manual strangulation, 2 cases; other, 1 case) during forensic autopsies; intact skin from the same individual was used as a control. HSP27 expression was detected in 17.4% of keratinocytes in the intact skin samples. In the compressed region, the frequency of HSP27 expression in keratinocytes was 75.8%, which was significantly higher than that in intact skin. Similarly, HSP70 expression was 24.8% in intact skin samples and 81.9% in compressed skin samples, significantly higher in compressed skin than in intact skin samples. This increase in case compression cases may be due to the cell defence role of HSPs. From a forensic pathology perspective, the immunohistochemical examination of HSP27 and HSP70 expression in neck skin could be considered a valuable marker for diagnosing traces of antemortem compression.

Neonatal Hypoxia Ischaemia: Mechanisms, Models, and Therapeutic Challenges

Neonatal hypoxia-ischaemia (HI) is the most common cause of death and disability in human neonates, and is often associated with persistent motor, sensory, and cognitive impairment. Improved intensive care technology has increased survival without preventing neurological disorder, increasing morbidity throughout the adult population. Early preventative or neuroprotective interventions have the potential to rescue brain development in neonates, yet only one therapeutic intervention is currently licensed for use in developed countries. Recent investigations of the transient cortical layer known as subplate, especially regarding subplate's secretory role, opens up a novel set of potential molecular modulators of neonatal HI injury. This review examines the biological mechanisms of human neonatal HI, discusses evidence for the relevance of subplate-secreted molecules to this condition, and evaluates available animal models. Neuroserpin, a neuronally released neuroprotective factor, is discussed as a case study for developing new potential pharmacological interventions for use post-ischaemic injury.

Serum Hsp70 Antigen: Early Diagnosis Marker in Perinatal Asphyxia

Background:

Perinatal asphyxia is an important cause of mortality and permanent neurological and developmental deficit. Early and accurate diagnosis would help to establish the likely prognosis and may also help in determining the most appropriate treatment. Studies in experimental animal models suggest that a protein called Hsp70 may be a good and potentially useful marker of cellular stress that may be clinically useful in determining the presence of neonatal asphyxia.

Objectives:

Regarding the importance of early and accurate diagnosis of asphyxia, we conducted this study, which is the first investigation of the comparison of the serum Hsp70 antigen level between asphyxiated and healthy infants.

Patients and Methods:

In this observational study, the serum concentrations of Hsp70 antigen were compared between neonates suffering from perinatal asphyxia (n = 50) and normal neonates (n = 51). The inclusion criteria for the cases were neonates who had reached term and had at least two clinical criteria of asphyxia. Exclusion criteria were babies with gestational age < 37 weeks, infants with congenital abnormalities or positive blood culture. Exclusion criteria in this group were the requirement to hospital stay during first week of the life or babies whose mothers had difficulties during pregnancy or delivery. Term neonates without major anomalies who had asphyxia during delivery were enrolled in the first six hours after delivery, and control group consisted of healthy term neonates without problems and normal delivery process in the first week of life. The cord blood was taken during labor to measure Hsp70 antigen level by using an in-house ELISA (The enzyme-linked immunosorbent assay).

Results:

The median values of serum anti Hsp70 titers were significantly higher in asphyxiated neonates compared with non-asphyxiated neonates (0.36 [0.04 - 1.14] vs 0.24 [0.01 - 0.63]). At cutoff point = 0.3125 ng/mL, sensitivity was 58% and specificity 76% based on ROC curve.

Conclusions:

A significant difference between the serum concentrations of Hsp70 of the control and patient group was observed in this study. It is inferred serum concentrations of Hsp70 antigen may be a useful marker for the early diagnosis of that prenatal hypoxia.

A technique for systemic mesenchymal stem cell transplantation in newborn rat pups

Mesenchymal stem cells (MSC) have the potential to aid tissue regeneration. Intravenous (IV) MSC administration is currently being assessed following tissue injury. However, few studies have been performed to establish a safe and effective method of IV MSC infusion for newborns. We have established a safe, nontraumatic and effective technique for systemic MSC transplantation in newborn rats. Yellow-fluorescent-protein (YFP)-labeled MSC were characterized using MSC markers and their differentiation potential was confirmed. Rat pups were delivered by C-section on gestational day 21. The umbilical vein (UV) was cannulated and used for IV injection of MSC or saline control, which was performed under ultrasonographic imaging. An additional control group consisted of UV MSC injection in adult mice. Mean operating time, success rate of cannulation and death rate were recorded. YFP-MSC quantification in multiple organs was performed. Mean operating time was 3.9 ± 1.1 min. The success of UV MSC injection was 92.8%. The immediate and 24 hr delayed death rate for rat pups was significantly lower than that of adult mice (p < .05). No pups receiving saline injection died. After locating the patent foramen ovale (PFO) of newborn pups by ultrasonographic imaging, extra pulse-waves and wave-shape changes were detected when MSC were injected. The number of YFP-MSC was 15.8 ± 4.1 cells per visual field (CPVF) in the lungs, 2.9 ± 1.2 CPVF in the heart, and 19.8 ± 5.0 CPVF in the intestines. We conclude that IV MSC infusion through the UV is a convenient, safe, and effective method for systemic MSC transplantation in prematurely delivered newborn rats.

Anti-hypoxia effect of adenovirus-mediated expression of heat shock protein 70 (HSP70) on primary cultured neurons

Heat shock protein 70 (HSP70) has attracted great attention recently in hypoxia injury because of its close link to the recovery after hypoxic-ischemic damage in organs. However, the cellular mechanism underlying its protective roles remains unclear. In this study, we developed a recombinant adenovirus containing HSP70-GFP (vAd-HSP70-GFP) and studied the effect of virus-mediated expression of exogenous HSP70 gene on neurons in response to hypoxia-reoxygenation injury. Virus-mediated expression of HSP70 was detected as early as 24 hr and lasted until 10 days after infection. Neurons with 48 hr vAd-HSP70-GFP infection were exposed to 0, 0.5, 1, 2, 3, or 4 hr hypoxia followed by 1 hr reoxygenation. The mRNA and protein levels of HSP70 in neurons exposed to different lengths of hypoxia were compared by using RT-PCR and Western blotting (WB). The 1-hr hypoxia exposure showed the most significant increases in the HSP70 mRNA and protein level compared with other exposure durations. MTT assay showed that HSP70 overexpression significantly increased the neuronal viability, accompanied by decreased lactate dehydrogenase (LDH) activity in the culture medium after hypoxia-reoxygenation. Neurons with vAd-HSP70-GFP exhibited increased levels of mitochondrial cytochrome C (Cyt-C) and decreased levels of cytoplasmic Cyt-C compared with vAd-GFP-infected cells. These results suggest a neuroprotective role of exogenous HSP70 against hypoxia-reoxygenation injury, possibly via preventing initiation of mitochondrial apoptosis.

Hypoxia-inducible factor 1/heme oxygenase 1 cascade as upstream signals in the prolife role of heat shock protein 70 at rostral ventrolateral medulla during experimental brain stem death

As the origin of a life-and-death signal that reflects central cardiovascular regulatory failure during brain stem death, the rostral ventrolateral medulla (RVLM) is a suitable neural substrate to delineate the cellular mechanisms of this fateful phenomenon. Based on a clinically relevant animal model that used the organophosphate pesticide mevinphos (Mev) as the experimental insult, we reported previously that heat shock protein 70 (HSP70) in RVLM plays a prolife role by ameliorating circulatory depression during brain stem death. Because Mev also elicits significant hypoxia in RVLM, this study evaluated the hypothesis that the hypoxia-inducible factor 1 (HIF-1)/heme oxygenase 1 (HO-1) cascade acts as upstream signals in the prolife role of HSP70 at RVLM during experimental brain stem death. In Sprague-Dawley rats maintained under propofol anesthesia, transcription activity assay or Western blot analysis revealed an enhancement of nuclear activity of HIF-1alpha or augmentation of HO-1 and HSP70 expression in RVLM preferentially during the prolife phase of Mev intoxication. Loss-of-function manipulations in RVLM using HIF-1alpha, HIF-1beta, or HO-1 antiserum or antisense hif-1alpha or ho-1 oligonucleotide significantly antagonized the preferential upregulation of HSP70, depressed the sustained cardiovascular regulatory machinery during the prolife phase, and exacerbated circulatory depression during the prodeath phase. Immunoneutralization of HIF-1alpha also blunted the preferential increase in HO-1 expression. We conclude that the repertoire of cellular events in RVLM during the prolife phase in our Mev intoxication of brain stem death triggered by hypoxia entails sequential activation of HIF-1, HO-1, and HSP70, leading to neuroprotection by amelioration of cardiovascular depression.

Transcriptomic changes in developing kidney exposed to chronic hypoxia

cDNA arrays compared gene expression in kidneys of neonatal mice subjected to 1, 2, and 4 weeks of chronic constant (CCH) or intermittent (CIH) hypoxia with normoxic littermates. Five to twenty percent of genes were regulated in each condition, with greater changes in CCH. Up-regulation of 42% of the solute carriers after 1 week of CCH suggests a strong activation of pH controlling pathways. Significant reduction in expression change of genes important in growth, development, and aging as a function of time indicates reduced maturation rate in CIH and CCH treatments. Regulated genes showed gender dependence in CCH, being higher in females than males at 1 week and higher in males than females thereafter. Transcriptional control was enhanced in CCH but not in CIH. Thus, CCH and CIH both alter gene expression and retard maturation with the more profound changes occurring in CCH than in CIH.

PS2 and HSP70 Expression in Rectal Adenocarcinomas

OBJECTIVE

To evaluate the expression of HSP70 and pS2 and to determine whether it may be an additional prognostic variable in the prediction of recurrence and survival in rectal adenocarcinomas.

METHODS

The paraffin sections of 45 patients with rectal carcinoma who were treated with surgical resection were stained with HSP70 and pS2 antibodies by using the standard biotin immunoperoxidase method. Cytoplasmic staining for both antibodies was scored semiquantitatively.

RESULTS

Only 16 (35.6%) tumors showed a positive cytoplasmic reaction with HSP70 antibody, while pS2 expression was observed in 26 (57.8%) tumors. There was an association between HSP70 and pS2 expression (P=0.002). No correlations were found between HSP70 and pS2 expression and tumor recurrence or overall survival and other prognostic factors. However, the type of surgical resection was significantly associated with pS2 expression status (P=0.013). Significant correlations were detected between tumor recurrence and other clinicopathologic parameters, such as clinical stage, lymph node involvement, and resection type (P=0.015, P=0.015, and P=0.03, respectively). Resection type was significantly associated with clinical outcome, recurrence, and metastasis (P=0.009, P=0.03, P<0.01, respectively). In addition, there was a statistically significant relationship between clinical stage and final outcome (P=0.005).

CONCLUSIONS

The strong correlation between pS2 expression and incomplete surgical resection suggests that pS2 may be related to invasive tumor behavior and may also play a role in tumor recurrence, although this latter association did not reach statistical significance in this study. HSP70 expression does not appear to be related to tumor invasiveness or tumor recurrence.

Mild Intermittent Hypoxia Does Not Induce Stress Responses in the Neonatal Rat Brain

We previously demonstrated that intermittent hypoxia evokes persistent changes in extracellular striatal dopamine, locomotor activity and executive function, using a rodent model emulating apnea of prematurity in which rat pups are exposed to 20-second bursts of hypoxic gas mix containing 10% oxygen (60 events/h; 6 h/day) from postnatal days 7 to 11. To determine whether subtle repetitive hypoxic insults also induce expression of stress-related genes, we employed real-time RT-PCR to assay gene transcription in neonatal rats subjected to the same paradigm. In addition, we also measured expression of stress-induced transcripts in an age-matched cohort following a more severe oxidative stressor: permanent focal ischemia. Four transcripts were elevated following the ischemic insult: heat shock protein 70 (Hsp70), CL100, nurr77, and heme oxygenase-1. In contrast, these transcripts were not regulated in the majority of neonatal rats exposed to an intermittent hypoxia protocol. Hsp70 was strongly induced, and CL100 and nurr77 were slightly induced in only 2 of 11 post-hypoxic rats compared to controls. These data demonstrate that a single ischemic event elicits expression of specific stress-related genes, whereas 5 days of brief intermittent hypoxic insults typically do not. Thus, it is unlikely that the neurochemical and behavioral morbidity observed in juvenile and adult rodents exposed to intermittent hypoxia during a critical period of brain development are related to stress-induced changes in gene expression.

Genetic polymorphisms and risk for acute renal failure in preterm neonates

Acute renal failure (ARF) affects about 10% of severely ill neonates. Recent studies have shown that genetic polymorphisms of proteins that play a role in neonatal physiology may contribute to individual susceptibility to both ARF and its risk factors. Our review summarizes the data collected to date. Studies have shown that the risk of preterm neonates for ARF is directly associated with a combination of high tumor necrosis factor-alpha producer and low interleukin-6 producer genotypes, as well as with low heat shock protein 72 producer genotype. Premature birth is itself the most important risk factor for a number of complications, including ARF, and recent studies have also shown an association between several maternal and fetal cytokine genetic polymorphisms and increased inflammatory response in preterm neonates. These polymorphisms could also be associated with increased risk for disorders such as sepsis and necrotizing enterocolitis, which lead to renal hypoperfusion and ARF. Genetic polymorphisms of the renin-angiotensin-aldosterone system have not been shown to directly influence risk for ARF. They may, however, be associated with patent ductus arteriosus, poor postnatal adaptation, and heart failure, which are all prevalent risk factors for ARF.

MYOBLAST SURVIVAL ENHANCEMENT AND TRANSPLANTATION SUCCESS IMPROVEMENT BY HEAT-SHOCK TREATMENT IN MDX MICE

BACKGROUND

Duchenne muscular dystrophy is a disease caused by the incapacity to synthesize dystrophin, which is implicated in the maintenance of the sarcolemma integrity. Myoblast transplantation is a potential treatment of this disease. However, most of the transplanted cells die very rapidly after their injection. Heat-shock proteins (HSPs) are over-expressed when cells undergo various types of stresses. Our goal was thus to investigate whether the expression of HSPs (HSP70 in particular) could protect myoblasts from death after intramuscular injection.

METHODS

HSP70 expression was induced by warming the cells at 42 degrees C for 60 minutes. HSP70 over-expression was quantified by Western blot analysis. The in vitro effect of HSPs on cell survival was evaluated by fluorescence-activated cell sorter analysis using the Hoescht/propidium iodide-labeling technique, and their in vivo effects were investigated by transplanting TnI-LacZ myoblasts labeled with [methyl-14C] thymidine.

RESULTS

Western blots indicated a sevenfold over-expression of the HSP70 after the heat-shock treatment. In vitro, the heat-shock treatment protected 18% of the cells from staurosporine- (1 microM) induced apoptosis. HSPs also protected 10% of the cells from death induced by either tumor necrosis factor-alpha (30 ng/mL) or glucose oxydase (0.1 U/mL). In vivo, the treatment improved the cell survival by twofold 5 days after the graft and increased by fourfold the long-term graft success.

CONCLUSIONS

The heat-shock treatment is a practical approach for improving the success of myoblast transplantation; in fact, using this kind of treatment, there is no need to genetically modify the cells before their transplantation.

Heat-Stress Enhances Proliferative Potential in Rat Soleus Muscle

The effects of heat-stress on proliferative potential in vivo were studied in rat skeletal muscle. Male Wistar rats (7-weeks-old) were divided into two groups: control (n=24) and heat-stressed (n=24). Rats in the experimental group were exposed to environmental heat-stress (41 degrees C for 60 min) in a heat chamber without anesthesia. The soleus muscles were dissected 1, 7, and 14 days after the heat exposure. The wet and dry weights of soleus muscle relative to body weight in the heat-stressed group were significantly higher than controls 7 days after the exposure (10.1% and 17.5%, respectively, p <0.05). The distribution of 5-bromo-2'-deoxyuridine and proliferating cell nuclear antigen-positive nuclei, that are the indicators for the cell proliferation, were increased by 2.2 and 5.1 times, respectively 1 day after heating (p <0.05). The expressions of heat shock protein 72 (58.0%) and phosphorylated p70S6 kinase (52.3%) were increased 1 day following heat exposure (p <0.05). These results suggest that heat-stress could promote the cell proliferation and induce muscular hypertrophy.

Association between heat shock protein 72 gene polymorphism and acute renal failure in premature neonates

Heat shock protein (HSP)70 plays an important role in the ischemic tolerance of fetal and neonatal kidney. We have investigated the association of genetic polymorphisms of the constitutive HSP70 (HSP73) and the inducible HSP70 (HSP72) encoding genes with the risk of acute renal failure (ARF) in very low birth weight (VLBW) neonates. Thirty-seven VLBW neonates with ARF and 93 VLBW neonates without ARF were enrolled in the study. The presence of HSP72 (1267)AG and HSP73 (190)GC polymorphism was analyzed from dried blood samples by PCR and restriction length fragment polymorphism. Allelic prevalence was related to reference values obtained in 131 healthy adults. Stepwise binary logistic regression was applied to determine the independent effect of the established risk factors to the development of ARF. Sixteen of 37 VLBW neonates with ARF and 18 of 93 VLBW neonates without ARF were homozygous for HSP72 (1267)G allele (p </= 0.01). The association between HSP72 (1267)GG genotype and ARF remained at the level of significance (p = 0.05) when it was adjusted for established risk factors of neonatal ARF. Prevalence of HSP72 (1267)GG was also higher in VLBW neonates than in the reference population (p < 0.05) and in VLBW neonates with infant respiratory distress syndrome than in those without (p < 0.001). We found that in VLBW neonates carrying HSP72 (1267)GG genetic variation, which is associated with low inducibility of HSP72, the risk of ARF was increased. Therefore, VLBW neonates with (1267)GG might express less HSP72 and might be less protected against ARF.