Heat shock proteins and virus replication: hsp70s as mediators of the antiviral effects of prostaglandins

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

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

Suppressed anti-inflammatory heat shock response in high-risk COVID-19 patients: lessons from basic research (inclusive bats), light on conceivable therapies

The major risk factors to fatal outcome in COVID-19 patients, i.e., elderliness and pre-existing metabolic and cardiovascular diseases (CVD), share in common the characteristic of being chronic degenerative diseases of inflammatory nature associated with defective heat shock response (HSR). The molecular components of the HSR, the principal metabolic pathway leading to the physiological resolution of inflammation, is an anti-inflammatory biochemical pathway that involves molecular chaperones of the heat shock protein (HSP) family during homeostasis-threatening stressful situations (e.g., thermal, oxidative and metabolic stresses). The entry of SARS coronaviruses in target cells, on the other hand, aggravates the already-jeopardized HSR of this specific group of patients. In addition, cellular counterattack against virus involves interferon (IFN)-mediated inflammatory responses. Therefore, individuals with impaired HSR cannot resolve virus-induced inflammatory burst physiologically, being susceptible to exacerbated forms of inflammation, which leads to a fatal "cytokine storm". Interestingly, some species of bats that are natural reservoirs of zoonotic viruses, including SARS-CoV-2, possess an IFN-based antiviral inflammatory response perpetually activated but do not show any sign of disease or cytokine storm. This is possible because bats present a constitutive HSR that is by far (hundreds of times) more intense and rapid than that of human, being associated with a high core temperature. Similarly in humans, fever is a physiological inducer of HSR while antipyretics, which block the initial phase of inflammation, impair the resolution phase of inflammation through the HSR. These findings offer a rationale for the reevaluation of patient care and fever reduction in SARS, including COVID-19.

VER-155008 induced Hsp70 proteins expression in fish cell cultures while impeding replication of two RNA viruses

The heat-shock protein 70 (Hsp70) inhibitor, VER-155008 (VER), was explored as a potential antiviral agent for two RNA viruses important to fish aquaculture, viral hemorrhagic septicemia virus (VHSV) and infectious pancreatic necrosis virus (IPNV). Studies were done at a temperature of 14 °C, and with cell lines commonly used to propagate these viruses. These were respectively EPC from fathead minnow for VHSV and CHSE-214 from Chinook salmon embryo for IPNV. Additionally, both viruses were studied with the Atlantic salmon heart endothelial cell line ASHe. For both VHSV and IPNV, 25 μM VER impeded replication. This was evidenced by delays in the development of cytopathic effect (CPE) and the expression of viral proteins, N for VHSV and VP2 for IPNV, and by less production of viral RNA and of viral titre. As VER inhibits the activity of Hsp70 family members, these results suggest that VHSV and IPNV utilize one or more Hsp70s in their life cycles. Yet neither virus induced Hsp70. Surprisingly VER alone induced Hsp70, but whether this induction modulated VER's antiviral effects is unknown. Exploring this apparent paradox in the future should improve the usefulness of VER as an antiviral agent.

Prostaglandin A1 triggers Mayaro virus inhibition and heat shock protein 70 expression in an epithelial cell model

INTRODUCTION

The Mayaro virus (MAYV), which is an arbovirus closely related to the Chikungunya virus, causes a dengue-like acute illness that is endemic to Central and South America. We investigated the anti-MAYV activity of prostaglandin A1 (PGA1), a hormone which exhibits antiviral activity against both ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) viruses. Further, we examined the effects of inducting the stress protein HSP70 following PGA1 treatment.

METHODS

Hep-2 cells infected with MAYV were treated with PGA1 (0.1-6μg/ml) 12h before infection and for different periods post-infection. Inhibition of viral replication inhibition was analyzed via viral titer determination, whereas the effect of PGA1 on viral morphogenesis was examined via transmission electron microscopy (TEM). Autoradiography (with 35S methionine labeling) and western blotting were used to assess the effect of PGA1 treatment on viral and cellular protein synthesis, and on HSP70 induction, respectively.

RESULTS

PGA1 strongly reduced viral replication in Hep-2 cells, particularly when added during the early stages of viral replication. Although PGA1 treatment inhibited viral replication by 95% at 24 hours post-infection (hpi), viral structural protein synthesis was inhibited only by 15%. TEM analysis suggested that PGA1 inhibited replication before viral morphogenesis. Western blot and densitometry analyses showed that PGA1 treatment increased HSP70 protein levels, although this was not detectable via autoradiography.

CONCLUSIONS

PGA1 inhibits MAYV replication in Hep-2 cells at early stages of viral replication, prior to production of viral structural proteins, possibly via HSP70 induction.

Roles of heat shock factor 1 beyond the heat shock response

Various stress factors leading to protein damage induce the activation of an evolutionarily conserved cell protective mechanism, the heat shock response (HSR), to maintain protein homeostasis in virtually all eukaryotic cells. Heat shock factor 1 (HSF1) plays a central role in the HSR. HSF1 was initially known as a transcription factor that upregulates genes encoding heat shock proteins (HSPs), also called molecular chaperones, which assist in refolding or degrading injured intracellular proteins. However, recent accumulating evidence indicates multiple additional functions for HSF1 beyond the activation of HSPs. Here, we present a nearly comprehensive list of non-HSP-related target genes of HSF1 identified so far. Through controlling these targets, HSF1 acts in diverse stress-induced cellular processes and molecular mechanisms, including the endoplasmic reticulum unfolded protein response and ubiquitin-proteasome system, multidrug resistance, autophagy, apoptosis, immune response, cell growth arrest, differentiation underlying developmental diapause, chromatin remodelling, cancer development, and ageing. Hence, HSF1 emerges as a major orchestrator of cellular stress response pathways.

Nitric oxide-heat shock protein axis in menopausal hot flushes: neglected metabolic issues of chronic inflammatory diseases associated with deranged heat shock response

BACKGROUND

Although some unequivocal underlying mechanisms of menopausal hot flushes have been demonstrated in animal models, the paucity of similar approaches in humans impedes further mechanistic outcomes. Human studies might show some as yet unexpected physiological mechanisms of metabolic adaptation that permeate the phase of decreased oestrogen levels in both symptomatic and asymptomatic women. This is particularly relevant because both the severity and time span of hot flushes are associated with increased risk of chronic inflammatory disease. On the other hand, oestrogen induces the expression of heat shock proteins of the 70 kDa family (HSP70), which are anti-inflammatory and cytoprotective protein chaperones, whose expression is modulated by different types of physiologically stressful situations, including heat stress and exercise. Therefore, lower HSP70 expression secondary to oestrogen deficiency increases cardiovascular risk and predisposes the patient to senescence-associated secretory phenotype (SASP) that culminates in chronic inflammatory diseases, such as obesities, type 2 diabetes, neuromuscular and neurodegenerative diseases.

OBJECTIVE AND RATIONALE

This review focuses on HSP70 and its accompanying heat shock response (HSR), which is an anti-inflammatory and antisenescent pathway whose intracellular triggering is also oestrogen-dependent via nitric oxide (NO) production. The main goal of the manuscript was to show that the vasomotor symptoms that accompany hot flushes may be a disguised clue for important neuroendocrine alterations linking oestrogen deficiency to the anti-inflammatory HSR.

SEARCH METHODS

Results from our own group and recent evidence on hypothalamic control of central temperature guided a search on PubMed and Google Scholar websites.

OUTCOMES

Oestrogen elicits rapid production of the vasodilatory gas NO, a powerful activator of HSP70 expression. Whence, part of the protective effects of oestrogen over cardiovascular and neuroendocrine systems is tied to its capacity of inducing the NO-elicited HSR. The hypothalamic areas involved in thermoregulation (infundibular nucleus in humans and arcuate nucleus in other mammals) and whose neurons are known to have their function altered after long-term oestrogen ablation, particularly kisspeptin-neurokinin B-dynorphin neurons, (KNDy) are the same that drive neuroprotective expression of HSP70 and, in many cases, this response is via NO even in the absence of oestrogen. From thence, it is not illogical that hot flushes might be related to an evolutionary adaptation to re-equip the NO-HSP70 axis during the downfall of circulating oestrogen.

WIDER IMPLICATIONS

Understanding of HSR could shed light on yet uncovered mechanisms of menopause-associated diseases as well as on possible manipulation of HSR in menopausal women through physiological, pharmacological, nutraceutical and prebiotic interventions. Moreover, decreased HSR indices (that can be clinically determined with ease) in perimenopause could be of prognostic value in predicting the moment and appropriateness of starting a HRT.

Analysis of the spleen proteome of chickens infected with reticuloendotheliosis virus

Infection with reticuloendotheliosis virus (REV), a gammaretrovirus in the family Retroviridae, can result in immunosuppression and subsequent increased susceptibility to secondary infections. In the present study, we identified differentially expressed proteins in the spleens of chickens infected with the REV-A HLJ07I strain, using two-dimensional gel electrophoresis on samples from time points coinciding with different phases of the REV life cycle. Differentially expressed proteins were identified using one-dimensional liquid chromatography electrospray ionization tandem mass spectrometry (1D LC ESI MS/MS). Comparative analysis of multiple gels revealed that the majority of changes occurred at early stages of infection. In total, 60 protein spots representing 28 host proteins were detected as either quantitatively (false discovery rate [FDR] ≤0.05 and fold change ≥2) or qualitatively differentially expressed at least once during different sampling points. The differentially expressed proteins identified in this study included antioxidants, molecular chaperones, cellular metabolism, formation of the cytoskeleton, signal transduction, cell proliferation and cellar aging. The present findings provide a basis for further studies to elucidate the role of these proteins in REV-host interactions. This could lead to a better understanding of REV infection mechanisms that cause immune suppression.

Comparative gene expression of Wigglesworthia inhabiting non-infected and Trypanosoma brucei gambiense-infected Glossina palpalis gambiensis flies

Tsetse flies (Glossina sp.) that transmit trypanosomes causing human (and animal) African trypanosomiasis (HAT and AAT, respectively) harbor symbiotic microorganisms, including the obligate primary symbiont Wigglesworthia glossinidia. A relationship between Wigglesworthia and tsetse fly infection by trypanosomes has been suggested, as removal of the symbiont results in a higher susceptibility to midgut infection in adult flies. To investigate this relationship and to decipher the role of W. glossinidia in the fly's susceptibility to trypanosome infection, we challenged flies with trypanosomes and subsequently analyzed and compared the transcriptomes of W. glossinidia from susceptible and refractory tsetse flies at three time points (3, 10, and 20 days). More than 200 W. glossinidia genes were found to be differentially expressed between susceptible and refractory flies. The high specificity of these differentially expressed genes makes it possible to distinguish Wigglesworthia inhabiting these two distinct groups of flies. Furthermore, gene expression patterns were observed to evolve during the infection time course, such that very few differentially expressed genes were found in common in Wigglesworthia from the 3-, 10- and 20-day post-feeding fly samples. The overall results clearly demonstrate that the taking up of trypanosomes by flies, regardless of whether flies proceed with the developmental program of Trypanosoma brucei gambiense, strongly alters gene expression in Wigglesworthia. These results therefore provide a novel framework for studies that aim to decrease or even abolish tsetse fly vector competence.

Hsp70 positively regulates porcine circovirus type 2 replication in vitro

The Hsp70 chaperone plays a central role in multiple processes within cells. Porcine circovirus type 2 (PCV2) is the essential causal agent of post-weaning multisystemic wasting syndrome (PMWS), which has spread worldwide. But the mechanism of PCV2 replication remains poorly understood. In this study, we firstly found the positive effect of heat stress on the replication of PCV2 in the continuous porcine monocytic cell line 3D4/31. Downregulation of Hsp70 by the specific chaperone inhibitor Quercetin or RNA interference and upregulation of Hsp70 by expression from a recombinant adenovirus showed that Hsp70 enhanced PCV2 genome replication and virion production. A specific interaction between Hsp70 and PCV2 Cap was confirmed by colocalization by confocal microscopy and co-immunoprecipitation. Furthermore, the NF-κB pathway was activated and caspase-3 activity was reduced when Hsp70 was overexpressed in PCV2-infected 3D4/31 cells. These data suggested that Hsp70 positively regulated PCV2 replication, which being helpful for understanding the molecular mechanism of PCV2 infection.

Transcription of liver X receptor is down-regulated by 15-deoxy-Δ(12,14)-prostaglandin J(2) through oxidative stress in human neutrophils

Liver X receptors (LXRs) are ligand-activated transcription factors of the nuclear receptor superfamily. They play important roles in controlling cholesterol homeostasis and as regulators of inflammatory gene expression and innate immunity, by blunting the induction of classical pro-inflammatory genes. However, opposite data have also been reported on the consequences of LXR activation by oxysterols, resulting in the specific production of potent pro-inflammatory cytokines and reactive oxygen species (ROS). The effect of the inflammatory state on the expression of LXRs has not been studied in human cells, and constitutes the main aim of the present work. Our data show that when human neutrophils are triggered with synthetic ligands, the synthesis of LXRα mRNA became activated together with transcription of the LXR target genes ABCA1, ABCG1 and SREBP1c. An inflammatory mediator, 15-deoxy-Δ^12,14-prostaglandin J₂ (15dPGJ₂), hindered T0901317-promoted induction of LXRα mRNA expression together with transcription of its target genes in both neutrophils and human macrophages. This down-regulatory effect was dependent on the release of reactive oxygen species elicited by 15dPGJ₂, since it was enhanced by pro-oxidant treatment and reversed by antioxidants, and was also mediated by ERK1/2 activation. Present data also support that the 15dPGJ₂-induced serine phosphorylation of the LXRα molecule is mediated by ERK1/2. These results allow to postulate that down-regulation of LXR cellular levels by pro-inflammatory stimuli might be involved in the development of different vascular diseases, such as atherosclerosis.

Hsp70 protein positively regulates rabies virus infection

The Hsp70 chaperone plays a central role in multiple processes within cells, including protein translation, folding, intracellular trafficking, and degradation. This protein is implicated in the replication of numerous viruses. We have shown that rabies virus infection induced the cellular expression of Hsp70, which accumulated in Negri body-like structures, where viral transcription and replication take place. In addition, Hsp70 is present in both nucleocapsids purified from infected cells and in purified virions. Hsp70 has been shown to interact with the nucleoprotein N. The downregulation of Hsp70, using specific chaperone inhibitors, such as quercetin or RNA interference, resulted in a significant decrease of the amount of viral mRNAs, viral proteins, and virus particles. These results indicate that Hsp70 has a proviral function during rabies virus infection and suggest that Hsp70 is involved in at least one stage(s) of the viral life cycle, such as viral transcription, translation, and/or production. The mechanism by which Hsp70 controls viral infection will be discussed.

Proteomic analysis of an Aedes albopictus cell line infected with Dengue serotypes 1 and 3 viruses

Background

Proteomic analysis was performed to identify proteins regulated during infection by Dengue serotypes 1 and 3 in an Aedes albopictus cell line. The potential of these viruses to cause severe disease at primary infection is of interest although few studies have been performed with these two Dengue serotypes.

Results

The most relevant observation of our study is the significant overexpression of proteins involved in the cellular stress response and the glycolysis pathway after 48 hours of infection. Viral infection activates the translation of some host genes, which may result in stress due to responses involving unfolded proteins.

Conclusions

Therefore, the oxidation reduction and glycolytic mechanisms could participate in the antiviral response against Dengue virus. The results of our study should help to improve our knowledge of the virus-mosquito interaction at a cellular level with the aim of designing efficient strategies for the control of Dengue virus.

Cellular heat shock factor 1 positively regulates human immunodeficiency virus-1 gene expression and replication by two distinct pathways

Human immunodeficiency virus-1 (HIV-1) infection leads to changes in cellular gene expression, which in turn tend to modulate viral gene expression and replication. Cellular heat shock proteins (HSPs) are induced upon heat shock, UV irradiation and microbial or viral infections. We have reported earlier Nef-dependent induction of HSP40 leading to increased HIV-1 gene expression; however, the mechanism of induction remained to be elucidated. As expression of HSPs is regulated by heat shock factors (HSFs), we have now studied the role of HSF1 not only in Nef-dependent HSP40 induction but also in HIV-1 gene expression. Our results show that HSF1 is also induced during HIV-1 infection and it positively regulates HIV-1 gene expression by two distinct pathways. First, along with Nef it activates HSP40 promoter which in turn leads to increased HIV-1 gene expression. Second, HSF1 directly interacts with newly identified HSF1 binding sequence on HIV-1 LTR promoter and induces viral gene expression and replication. Thus, the present work not only identifies a molecular basis for HSF1-mediated enhancement of viral replication but also provides another example of how HIV-1 uses host cell machinery for its successful replication in the host.

Role of Heat Shock Proteins in Viral Infection

One of the most intriguing and less known aspects of the interaction between viruses and their host is the impact of the viral infection on the heat shock response (HSR). While both a positive and a negative role of different heat shock proteins (HSP) in the control of virus replication has been hypothesized, HSP function during the virus replication cycle is still not well understood. This chapter describes different aspects of the interactions between viruses and heat shock proteins during infection of mammalian cells: the first part focuses on the modulation of the heat shock response by human viral pathogens; the second describes the interactions of HSP and other chaperones with viral components, and their function during different steps of the virus replication cycle; the last part summarizes our knowledge on the effect of hyperthermia and HSR modulators on virus replication.

The cold adapted and temperature sensitive influenza A/Ann Arbor/6/60 virus, the master donor virus for live attenuated influenza vaccines, has multiple defects in replication at the restrictive temperature

We have previously determined that the temperature sensitive (ts) and attenuated (att) phenotypes of the cold adapted influenza A/Ann Arbor/6/60 strain (MDV-A), the master donor virus for the live attenuated influenza A vaccines (FluMist), are specified by the five amino acids in the PB1, PB2 and NP gene segments. To understand how these loci control the ts phenotype of MDV-A, replication of MDV-A at the non-permissive temperature (39 degrees C) was compared with recombinant wild-type A/Ann Arbor/6/60 (rWt). The mRNA and protein synthesis of MDV-A in the infected MDCK cells were not significantly reduced at 39 degrees C during a single-step replication, however, vRNA synthesis was reduced and the nuclear-cytoplasmic export of viral RNP (vRNP) was blocked. In addition, the virions released from MDV-A infected cells at 39 degrees C exhibited irregular morphology and had a greatly reduced amount of the M1 protein incorporated. The reduced M1 protein incorporation and vRNP export blockage correlated well with the virus ts phenotype because these defects could be partially alleviated by removing the three ts loci from the PB1 gene. The virions and vRNPs isolated from the MDV-A infected cells contained a higher level of heat shock protein 70 (Hsp70) than those of rWt, however, whether Hsp70 is involved in thermal inhibition of MDV-A replication remains to be determined. Our studies demonstrate that restrictive replication of MDV-A at the non-permissive temperature occurs in multiple steps of the virus replication cycle.

The varicella-zoster virus immediate-early 63 protein affects chromatin-controlled gene transcription in a cell-type dependent manner

Background

Varicella Zoster Virus Immediate Early 63 protein (IE63) has been shown to be essential for VZV replication, and critical for latency establishment. The activity of the protein as a transcriptional regulator is not fully clear yet. Using transient transfection assays, IE63 has been shown to repress viral and cellular promoters containing typical TATA boxes by interacting with general transcription factors.

Results

In this paper, IE63 regulation properties on endogenous gene expression were evaluated using an oligonucleotide-based micro-array approach. We found that IE63 modulates the transcription of only a few genes in HeLa cells including genes implicated in transcription or immunity. Furthermore, we showed that this effect is mediated by a modification of RNA POL II binding on the promoters tested and that IE63 phosphorylation was essential for these effects. In MeWo cells, the number of genes whose transcription was modified by IE63 was somewhat higher, including genes implicated in signal transduction, transcription, immunity, and heat-shock signalling. While IE63 did not modify the basal expression of several NF-κB dependent genes such as IL-8, ICAM-1, and IκBα, it modulates transcription of these genes upon TNFα induction. This effect was obviously correlated with the amount of p65 binding to the promoter of these genes and with histone H3 acetylation and HDAC-3 removal.

Conclusion

While IE63 only affected transcription of a small number of cellular genes, it interfered with the TNF-inducibility of several NF-κB dependent genes by the accelerated resynthesis of the inhibitor IκBα.

Pesticide and pathogen: heat shock protein expression and acetylcholinesterase inhibition in juvenile Chinook salmon in response to multiple stressors

Rapid expression of heat shock protein (hsp) families in response to a variety of stressors has been demonstrated in many organisms, including fish. The present 60-d challenge study was designed to compare hsp induction in juvenile Chinook salmon following exposure to individual pesticides, virus, and both stressors combined. Heat shock protein expression patterns over time were monitored and related to the extent of virus infection and mortality. Acetylcholinesterase (AChE) inhibition and recovery in response to applied stressors were measured in brain. High enzyme inhibition levels have been correlated with imminent mortality, and other sublethal physiological effects have been observed in fish concurrent with depressed AChE activity. Mortality was elevated considerably in fish exposed to 0.08 microg/L of the pyrethroid esfenvalerate (EV). Mortality due to infectious hematopoietic necrosis virus (IHNV) was lower in groups previously treated with pesticides; however, these fish died sooner than individuals exposed to virus only. Both pesticides, EV and the organophosphate (OP) chlorpyrifos (CP), as well as virus exposure, induced hsp expression, but highest hsp levels were observed after the combined treatments, suggesting an additive effect between virus and pesticides. Highest virus titers were accompanied by strongest hsp induction, indicating a connection between virus concentration and hsp expression. In conclusion, the measurement of hsp expression appears to be a very sensitive, integrative indicator of stress. Esfenvalerate and IHNV did not affect AChE activity, and exposure to 3.7 microg/L CP led to significantly inhibited AChE for at least 20 d. The time required for complete recovery of AChE activity raises concern about deleterious behavioral effects.

Hsp70 negatively controls rotavirus protein bioavailability in caco-2 cells infected by the rotavirus RF strain

Previous studies demonstrated that the induction of the heat shock protein Hsp70 in response to viral infection is highly specific and differs from one cell to another and for a given virus type. However, no clear consensus exists so far to explain the likely reasons for Hsp70 induction within host cells during viral infection. We show here that upon rotavirus infection of intestinal cells, Hsp70 is indeed rapidly, specifically, and transiently induced. Using small interfering RNA-Hsp70-transfected Caco-2 cells, we observed that Hsp70 silencing was associated with an increased virus protein level and enhanced progeny virus production. Upon Hsp70 silencing, we observed that the ubiquitination of the main rotavirus structural proteins was strongly reduced. In addition, the use of proteasome inhibitors in infected Caco-2 cells was shown to induce an accumulation of structural viral proteins. Together, these results are consistent with a role of Hsp70 in the control of the bioavailability of viral proteins within cells for virus morphogenesis.

Specific binding of heat shock protein 70 with HN-protein inhibits the HN-protein assembly in Sendai virus-infected Vero cells

The production of hemagglutinating virus of Japan (HVJ; Sendai virus) was inhibited at 41 degrees C, whereas it was normal at 37 degrees C. In the infected Vero cells, viral specific proteins were synthesized even at 41 degrees C, but the synthesized HN protein was not integrated into the cell membrane, resulting in the inhibition of viral production. To investigate the relationship of HSP70 to the inhibition of HN-protein integration, the expression of HSP70 was induced by prostaglandin A1 (PGA1) at 37 degrees C, and the influence on viral infection was examined. The induction of HSP70 at 37 degrees C inhibited the viral production. Viral proteins were also synthesized, even in the presence of PGA1. However, HN protein was not as present on the cell membrane following PGA1-treatment as it was at 41 degrees C, whereas F protein was detected. An immunoprecipitation assay showed that HSP70 was coprecipitated with HN protein, but not with F protein. The results suggested that the specific interaction of HSP70 with HN protein prevented the protein from integrating into the cell membrane. In addition, the abnormal virus-like particles, of which HN protein and nucleocapsid were ablated, were released in the culture medium at 41 degrees C, although the size was smaller than the normal viral virions. The results suggest that HN protein is necessary for viral morphogenesis.

Downregulation of varicella-zoster virus (VZV) immediate-early ORF62 transcription by VZV ORF63 correlates with virus replication in vitro and with latency

Varicella-zoster virus (VZV) open reading frame 63 (ORF63) protein is expressed during latency in human sensory ganglia. Deletion of ORF63 impairs virus replication in cell culture and establishment of latency in cotton rats. We found that cells infected with a VZV ORF63 deletion mutant yielded low titers of cell-free virus and produced very few enveloped virions detectable by electron microscopy compared with those infected with parental virus. Microarray analysis of cells infected with a recombinant adenovirus expressing ORF63 showed that transcription of few human genes was affected by ORF63; a heat shock 70-kDa protein gene was downregulated, and several histone genes were upregulated. In experiments using VZV transcription arrays, deletion of ORF63 from VZV resulted in a fourfold increase in expression of ORF62, the major viral transcriptional activator. A threefold increase in ORF62 protein was observed in cells infected with the ORF63 deletion mutant compared with those infected with parental virus. Cells infected with ORF63 mutants impaired for replication and latency (J. I. Cohen, T. Krogmann, S. Bontems, C. Sadzot-Delvaux, and L. Pesnicak, J. Virol. 79:5069-5077, 2005) showed an increase in ORF62 transcription compared with those infected with parental virus. In contrast, cells infected with an ORF63 mutant that is not impaired for replication or latency showed ORF62 RNA levels equivalent to those in cells infected with parental virus. The ability of ORF63 to downregulate ORF62 transcription may play an important role in virus replication and latency.

Development of a sensitive assay for the measurement of antibodies against heat shock protein binding protein 1 (HspBP1): increased levels of anti-HspBP1 IgG are prevalent in HIV infected subjects

The 70 kDa heat shock protein (Hsp70) is generally considered to be an intracellular protein, however, there is evidence that Hsp70 can be found in the extracellular environment. Hsp70 and antibodies against Hsp70 have been reported in human serum. Recent evidence has shown that Hsp70 antibodies are elevated in HIV infected individuals. This study reports on the antibody levels against a co-chaperone, HspBP1, that regulates Hsp70 activity. We have developed a solid-phase enzyme linked assay for the determination of anti-HspBP1 IgG antibodies. We report here that HspBP1 antibodies are present in human serum and the levels are elevated approximately twofold in HIV infected patients. There was no correlation between HspBP1 antibody levels and clinical parameters nor was there a relation between anti-Hsp70 levels and anti-HspBP1 levels. The presence of HspBP1 antibodies in human serum suggests that the protein may also be present in the serum. The increased level of HspBP1 antibodies in HIV infected individuals suggests a relationship directly to the virus or indirectly to secondary consequences of HIV infection.

Changes in serum levels of heat shock protein 70 in preterm delivery and pre-eclampsia

AIM

The aim of this study was to investigate heat-shock protein (Hsp)70 as a novel marker to evaluate the curative effects of treatment for preterm delivery high-risk patients and pre-eclampsia.

METHODS

After obtaining informed consent, serum samples were collected from 31 preterm delivery high-risk patients with a tocolysis index of three points or above (A), seven pre-eclampsia patients (P), 46 normal pregnant women (B), and seven non-pregnant women (C). Of the 31 preterm delivery high-risk patients, 15 had preterm delivery (Ap) and 16 had full-term delivery (Af). The levels of Hsp70 were measured using enzyme-linked immunosorbent assay.

RESULTS

The Hsp70 levels in normal pregnant women were 8.6 +/- 1.9 ng/mL (first trimester), 5.5 +/- 1.0 ng/mL (second trimester) and 5.5 +/- 0.7 ng/mL (third trimester). There was no statistical difference in the Hsp70 levels between the three trimesters. The mean Hsp70 levels were 21.9 +/- 5.3 ng/mL (A), 35.3 +/- 9.6 ng/mL (Ap), 9.4 +/- 2.2 ng/mL (Af), 24.4 +/- 3.6 ng/mL (P), 6.1 +/- 0.6 ng/mL (B), and 2.4 +/- 0.6 ng/mL (C). Group Ap had significantly higher Hsp70 levels than group Af (P = 0.0112) and group B (P <0.0001). The duration of pregnancy after hospitalization for group Ap was significantly shorter than that for group Af (P=0.0088) and group B (P <0.0001). Group P also had significantly higher Hsp70 levels than group B (P <0.0001).

CONCLUSION

Because Hsp70 levels were particularly high in treatment-resistant preterm delivery cases, Hsp70 may prove to be a useful marker for evaluating the curative effects of treatment for preterm delivery.

Proteomics analysis of human astrocytes expressing the HIV protein Tat

Astrocyte infection in HIV has been associated with rapid progression of dementia in a subset of HIV/AIDS patients. Astrogliosis and microglial activation are observed in areas of axonal and dendritic damage in HIVD. In HIV-infected astrocytes, the regulatory gene tat is over expressed and mRNA levels for Tat are elevated in brain extracts from individuals with HIV-1 dementia. Tat can be detected in HIV-infected astrocytes in vivo. The HIV-1 protein Tat transactivates viral and cellular gene expression, is actively secreted mainly from astrocytes, microglia and macrophages, into the extracellular environment, and is taken up by neighboring uninfected cells such as neurons. The HIV-1 protein Tat released from astrocytes reportedly produces trimming of neurites, mitochondrial dysfunction and cell death in neurons, while protecting its host, the astrocyte. We utilized proteomics to investigate protein expression changes in human astrocytes intracellularly expressing Tat (SVGA-Tat). By coupling 2D fingerprinting and identification of proteins by mass spectrometry, we identified phosphatase 2A, isocitrate dehydrogenase, nuclear ribonucleoprotein A1, Rho GDP dissociation inhibitor alpha, beta-tubulin, crocalbin like protein/calumenin, and vimentin/alpha-tubulin to have decreased protein expression levels in SVGA-Tat cells compared to the SVGA-pcDNA cells. Heat shock protein 70, heme oxygenase-1, and inducible nitric oxide synthase were found to have increased protein expression in SVGA-Tat cells compared to controls by slotblot technique. These findings are discussed with reference to astrocytes serving as a reservoir for the HIV virus and how Tat promotes survival of the astrocytic host.

Quantitative expression profiling of immune response genes in rainbow trout following infectious haematopoietic necrosis virus (IHNV) infection or DNA vaccination

Infectious haematopoietic necrosis virus (IHNV) is a well-studied virus of salmonid fishes. A highly efficacious DNA vaccine has been developed against this virus and studies have demonstrated that this vaccine induces both an early and transient non-specific anti-viral phase as well as long-term specific protection. The mechanisms of the early anti-viral phase are not known, but previous studies noted changes in Mx gene expression, suggesting a role for type I interferon. This study used quantitative real-time reverse transcriptase PCR methodology to compare expression changes over time of a number of cytokine or cytokine-related genes in the spleen of rainbow trout following injection with poly I:C, live IHNV, the IHNV DNA vaccine or a control plasmid encoding the non-antigenic luciferase gene. The target genes included Mx-1, viral haemorrhagic septicaemia virus induced gene 8 (Vig-8), TNF-alpha1, TNF-alpha2, IL-1beta1, IL-8, TGF-beta1 and Hsp70. Poly I:C stimulation induced several genes but the strongest and significant response was observed in the Mx-1 and Vig-8 genes. The live IHN virus induced a significant response in all genes examined except TGF-beta1. The control plasmid construct and the IHNV DNA vaccine marginally induced a number of genes, but the main difference between these two groups was a statistically significant induction of the Mx-1 and Vig-8 genes by the IHNV vaccine only. The gene expression profiles elicited by the live virus and the IHNV DNA vaccine differed in a number of aspects but this study confirms the clear role for a type I interferon-like response in early anti-viral defence.

15-Deoxy-Δ12,14-prostaglandin J2 Induces Heme Oxygenase-1 Gene Expression in a Reactive Oxygen Species-dependent Manner in Human Lymphocytes

15-Deoxy-delta(12,14)-prostaglandin J(2) (15dPGJ(2) has been recently proposed as a potent anti-inflammatory agent. However, the mechanisms by which 15dPGJ(2) mediates its therapeutic effects in vivo are unclear. We demonstrate that 15dPGJ(2) at micromolar (2.5-10 microm) concentrations induces the expression of heme oxygenase-1 (HO-1), an anti-inflammatory enzyme, at both mRNA and protein levels in human lymphocytes. In contrast, troglitazone and ciglitazone, two thiazolidinediones that mimic several effects of 15dPGJ(2) through their binding to the peroxisome proliferator-activated receptor (PPAR)-gamma, did not affect HO-1 expression, and the positive effect of 15dPGJ(2) on this process was mimicked instead by other cyclopentenone prostaglandins (PG), such as PGD(2) (the precursor of 15dPGJ(2)) and PGA(1) and PGA(2) which do not interact with PPAR-gamma. Also, 15dPGJ(2) enhanced the intracellular production of reactive oxygen species (ROS) and increased xanthine oxidase activity in vitro. Inhibition of intracellular ROS production by N-acetylcysteine, TEMPO, Me(2)SO, 1,10-phenanthroline, or allopurinol resulted in a decreased 15dPGJ(2)-dependent HO-1 expression in the cells. Furthermore, buthionine sulfoximine, an inhibitor of reduced glutathione synthesis, or Fe(2+)/Cu(2+) ions enhanced the positive effect of 15dPGJ(2) on HO-1 expression. On the other hand, the inhibition of phosphatidylinositol 3-kinase or p38 mitogen-activated protein kinase, or the blockade of transcription factor NF-kappaB activation, hindered 15dPGJ(2)-elicited HO-1 expression. Collectively, the present data suggest that 15dPGJ(2) anti-inflammatory actions at pharmacological concentrations involve the induction of HO-1 gene expression through mechanisms independent of PPAR-gamma activation and dependent on ROS produced via the xanthine/xanthine oxidase system and/or through Fenton reactions. Both phosphatidylinositol 3-kinase and p38 mitogen-activated protein kinase signaling pathways also appear implicated in modulation of HO-1 expression by 15dPGJ(2).

Elevated levels of antibodies against 70 kDa heat shock proteins in the sera of patients with HIV infection

Heat shock proteins (Hsp), especially 70 kDa heat shock protein (Hsp70) play an important role in the life cycle of HIV-1 virus. Hsp70 is overexpressed in HIV-infected cells and this is the most abundant Hsp associated with HIV virions. The aim of our study was to investigate whether HIV infection increases the extent of specific humoral immune response against Hsp70. The serum concentration of anti-Hsp70 IgG antibodies was measured in 47 HIV-infected patients, and 62 healthy, HIV-seronegative persons. Nineteen patients on highly active anti-retroviral therapy (HAART) were followed for 24 months in a longitudinal study. Anti-Hsp70 antibodies were measured by ELISA, using recombinant human Hsp70. Levels of anti-Hsp70 antibodies were significantly (P < 0.0001) higher in the HIV-infected patients (median: 1409 (25th-75th percentile: 1031-2214) AU/ml) than in healthy control subjects (626 (429-970) AU/ml). In 19 HIV patients, serum levels of anti-Hsp70 antibodies significantly (P < 0.001) decreased during 24 (11-41) months HAART (1309 (887-2213) AU/ml before and 640 (386-959) AU/ml during HAART), accompanied by viral load reduction and CD4+ count elevation. It is concluded that HIV-infection induces a marked increase in the anti-Hsp70 antibody levels, which is consistent with the enhanced expression of Hsp70 on the surface of HIV-infected cells and/or incorporation of the protein into the membrane of HIV virions.

MAP kinase cascades are activated in astrocytes and preadipocytes by 15-deoxy-Delta(12-14)-prostaglandin J(2) and the thiazolidinedione ciglitazone through peroxisome proliferator activator receptor gamma-independent mechanisms involving reactive oxygenated species

15-Deoxy-Delta(12-14)-prostaglandin J(2) (dPGJ2) and thiazolidinediones are known as ligands for the peroxisome proliferator activator receptor gamma (PPAR gamma) a member of the nuclear receptor superfamily. Herein, we show that dPGJ2 activates, in cultured primary astrocytes, Erk, Jnk, p38 MAP kinase, and ASK1, a MAP kinase kinase kinase, which can be involved in the activation of Jnk and p38 MAP kinase. The activation kinetic is similar for the three MAP kinase. The activation of the MAP kinases is detectable around 0.5 h. The activation increases with dPGJ2 in a dose dependent manner (0-15 microm). A scavenger of reactive oxygenated species (ROS), N-acetylcysteine (NAC) at 20 mm, completely suppresses the activation of MAP kinases and ASK1, suggesting a role for oxidative stress in the activation mechanism. Other prostaglandin cyclopentenones than dPGJ2, A(2), and to a lesser degree, A(1) also stimulate the MAP kinases, although they do not bind to PPAR gamma. Ciglitazone (20 microm), a thiazolidinedione that mimics several effects of dPGJ2 in different cell types, also activates the three MAP kinase families and ASK1 in cultured astrocytes. However the activation is more rapid (it is detectable at 0.25 h) and more sustained (it is still strong after 4 h). NAC prevents the activation of the three MAP kinase families by ciglitazone. Another thiazolidinedione that binds to PPAR gamma, rosiglitazone, does not activate MAP kinases, indicating that the effect of ciglitazone on MAP kinases is independent of PPAR gamma. Ciglitazone and less strongly dPGJ2 activate Erk in undifferentiated cells of the adipocyte cell line 1B8. Ciglitazone also activates Jnk and p38 MAP kinase in these preadipocytes. Our findings suggest that a part of the biological effects of dPGJ2 and ciglitazone involve the activation of the three MAP kinase families probably through PPAR gamma-independent mechanisms involving ROS.

Specific incorporation of heat shock protein 70 family members into primate lentiviral virions

To determine if any heat shock proteins are incorporated into human immunodeficiency virus type 1 (HIV-1) virions in a manner similar to that of the peptidyl-prolyl isomerase cyclophilin A, we probed purified virions with antibodies against heat shock proteins Hsp27, Hsp40, Hsp60, Hsp70, Hsc70, and Hsp90. Of these proteins, Hsp60, Hsp70, and Hsc70 associated with virions purified based on either particle density or size and were shown to be incorporated within the virion membrane, where they were protected from digestion by exogenous protease. Virion incorporation of Hsp70 was also observed with HIV-2 and with simian immunodeficiency viruses SIV(MAC) and SIV(AGM), but it appears to be specific for primate lentiviruses, since Hsp70 was not detected in association with Moloney murine leukemia virus virions. Of the HIV-1 genes, gag was found to be sufficient for Hsp70 incorporation, though Hsp70 was roughly equimolar with pol-encoded proteins in virions.

Inhibition by prostaglandin PGA1 on the multiplication of influenza virus is a dose-dependent effect

Cyclopentenone prostaglandins (PGs), are strong inhibitors of the multiplicative cycle of a wide variety of enveloped RNA and DNA viruses. Their antiviral activity is generally associated with alterations in the synthesis or maturation of specific virus proteins. In this report, we describe the effect of cyclopentenone PGA1 on the replication of influenza A virus Ulster 73 in LLC-MK2 cells. PGA1 was found to inhibit viral replication in a dose-dependent fashion and virus particle yield was reduced at a PGA1 concentration, which did not suppress protein synthesis in mock-infected cells. The kinetic of late viral protein synthesis was delayed in PGA1-treated cells till 10 h post-infection; after that period, viral polypeptide synthesis appeared to be similar in PGA1-treated as well as untreated cells both infected by Ulster 73 virus. This finding suggests that PGA1 might interfere with one or more events in the viral multiplicative cycle such as protein synthesis and assembly, correct insertion of virus polypeptides into the cell membrane and, or maturation of Ulster 73 virion particles. In particular, inhibition of viral replication in LLC-MK2 cells by PGA1 is accompanied by the induction of a cellular polypeptide of 70K molecular weight. We identified this cell protein as a heat shock protein (HSP) related to the inducible isoform of HSP 70, a polypeptide of 72K molecular weight. Induction of this polypeptide by PGA1 was found to be dose-dependent and a substantial accumulation could be seen at a PGA1 concentration that did not inhibit cell protein synthesis in uninfected cells. HSP 70 synthesis started after the beginning of PGA1 treatment and remained at the same level for at least 10 h, leading us to hypothesize that the delay of production of late Ulster 73 proteins could be the consequence of HSP 70 synthesis. These results suggest that HSP 70 could play a role in the antiviral activity of cyclopentenone PGA1 in LLC-MK2 cells.

Induction of heat shock protein 70 by herbimycin A and cyclopentenone prostaglandins in smooth muscle cells

This study characterizes Hsp70 induction in human smooth muscle cells (SMC) by herbimycin A and cyclopentenone prostaglandins. The magnitude of Hsp70 induction by cyclopentenone prostaglandins was 8- to 10-fold higher than induction by herbimycin A. Hsp70 induction by delta12PGJ2 was first observed at 10 microM, rose to 4000-5000 ng/mL within one log unit and a maximum response was not observed; concentrations of delta12PGJ2 higher than 30 microM were toxic to the cells. A maximum response with herbimycin A (500 ng/mL) was reached at 0.05 microM and maintained to 1 microM without toxicity. Both, delta12PGJ2 and herbimycin A, were inhibited by dithiothreitol (DTT, 100 microM) at lower concentrations and became less sensitive to inhibition at higher concentrations. Hsp70 induction after incubation of SMC with delta12PGJ2 followed by addition of herbimycin A was significantly higher than Hsp70 induction after incubation with herbimycin A followed by addition of delta12PGJ2. When cells were incubated with [3H]-PGJ2, followed by protein denaturation, substantial radioactivity remained protein-bound suggesting that the prostaglandin must be covalently bound. Covalent binding was largely insensitive to DTT. Maximal Hsp70 induction was observed after 5 minutes of exposure of the cells to herbimycin A followed by a 20 hour recovery period in agent-free medium. Cells required 3-4 hours of exposure to delta12PGJ2 followed by a 20 hour recovery period in order to see high Hsp70 induction. Binding of the heat shock factor (HSF) to the heat shock element (HSE) in the presence of herbimycin A or delta12PGJ2, and the effects of DTT, mirrored the results of Hsp70 induction. The results suggest that probable differences between the 2 agents are at the level of the signal transduction prior to HSF activation.

Heat shock proteins: novel therapeutic tools for HIV-infection?

Heat shock proteins (Hsps), cyclophilins (Cyps) and FK binding proteins (FKBPs) form a family of intracellular chaperone molecules that facilitate protein folding and assembly. These stress proteins are selectively expressed in cells in response to a range of stimuli, including heat, lymphokine and microbial/viral infections. This review discusses the role of stress proteins in the HIV-1 viral life cycle, with regard to the development of specific Hsp-based therapeutic strategies against HIV-1 infection. Cumulative findings are cited implicating CypA, Hsp27, Hsp70 and FKBPs in host cell and viral activation, viral entry, assembly or formation of infectious virions. Biological response modifiers that show specific high-affinity interactions with Cyp, FKBPs and Hsps, including cyclosporins, FK-506 and cyclopentenone prostaglandins respectively, may block HIV-1 replication and infection, providing novel HIV-1 therapeutic strategies. Moreover, Hsp binding to viral complexes can enhance antiviral immunity, including natural killer (NK), antibody-dependent (ADCC), gamma delta T-cell and cytotoxic T-lymphocyte (CTL) activities against HIV-1 infected cells. The ability of Hsps to interact with HIV-1 viral proteins, combined with their inherent adjuvant and immunogenic properties indicates that Hsps may also serve as vehicles for antigen delivery and the design of AIDS vaccines.

Eicosanoids and the stomach

Eicosanoids are arachidonic acid derivatives that include prostaglandins, thromboxanes, and leukotrienes. During the last three decades, it has become evident that these bioactive lipids play a pivotal role in gastric physiology. The goal of the present review is to describe their involvement in the normal regulation of gastric secretion and gastric motility, as well as in gastric mucosal defense. Their role in gastric mucosal mitogenesis, apoptosis, inflammation, and immune modulatory responses is also discussed.

Induction of heat shock protein 70 by herbimycin A and cyclopentenone prostaglandins in smooth muscle cells

This study characterizes Hsp70 induction in human smooth muscle cells (SMC) by herbimycin A and cyclopentenone prostaglandins. The magnitude of Hsp70 induction by cyclopentenone prostaglandins was 8- to 10-fold higher than induction by herbimycin A. Hsp70 induction by delta12PGJ2 was first observed at 10 microM, rose to 4000-5000 ng/mL within one log unit and a maximum response was not observed; concentrations of delta12PGJ2 higher than 30 microM were toxic to the cells. A maximum response with herbimycin A (500 ng/mL) was reached at 0.05 microM and maintained to 1 microM without toxicity. Both, delta12PGJ2 and herbimycin A, were inhibited by dithiothreitol (DTT, 100 microM) at lower concentrations and became less sensitive to inhibition at higher concentrations. Hsp70 induction after incubation of SMC with delta12PGJ2 followed by addition of herbimycin A was significantly higher than Hsp70 induction after incubation with herbimycin A followed by addition of delta12PGJ2. When cells were incubated with [3H]-PGJ2, followed by protein denaturation, substantial radioactivity remained protein-bound suggesting that the prostaglandin must be covalently bound. Covalent binding was largely insensitive to DTT. Maximal Hsp70 induction was observed after 5 minutes of exposure of the cells to herbimycin A followed by a 20 hour recovery period in agent-free medium. Cells required 3-4 hours of exposure to delta12PGJ2 followed by a 20 hour recovery period in order to see high Hsp70 induction. Binding of the heat shock factor (HSF) to the heat shock element (HSE) in the presence of herbimycin A or delta12PGJ2, and the effects of DTT, mirrored the results of Hsp70 induction. The results suggest that probable differences between the 2 agents are at the level of the signal transduction prior to HSF activation.

Preconditioning of human smooth muscle cells via cyclopentenone prostaglandins protects against toxic effects of oxidized low-density lipoprotein

Human vascular smooth muscle cells (SMC) exhibit upregulation of inducible heat shock protein 70 (Hsp70), upon exposure to oxidized low-density lipoproteins (LDL(ox)). The presence of Hsp70 is thought to protect the cell against the toxic effects of the modified lipoprotein. In order to test this hypothesis, Hsp70 in SMC was upregulated by exposure to Delta(12) prostaglandin J(2) (Delta(12)PGJ(2)) before cells were exposed to LDL(ox). Hsp70 levels were measured after exposure to Delta(12)PGJ(2) and before exposure to LDL(ox). Cell protection was monitored after LDL(ox) exposure by determination of cell toxicity measured by cell lactate dehydrogenase (LDH) release into the medium. Cells treated with Delta(12)PGJ(2) exhibited a 23-fold increase in Hsp70 levels and 56% lower LDH activity release after exposure to LDL(ox) when compared to cells that were not pretreated with Delta(12)PGJ(2). In addition, cells pretreated with prostaglandins that did not induce Hsp70 did not exhibit increased tolerance against the toxic effects of LDL(ox). The results support a protective role for Hsp70 against the toxic effects of LDL(ox) and hint at the potential for the use of small molecules for the prevention of deleterious effects of LDL(ox) through heat shock protein upregulation.

Gene transfer into hippocampal slice cultures with an adenovirus vector driven by cytomegalovirus promoter: stable co-expression of green fluorescent protein and lacZ genes

Virus-mediated gene transfer into identified neurons of organotypic hippocampal slice cultures offers a great potential for studying the cellular and molecular mechanisms of synaptic plasticity. We describe here a new adenovirus vector Ad-GFP-lacZ carrying an early cytomegalovirus (CMV) gene promoter that efficiently co-transferred the beta-galactosidase (lacZ) and green fluorescent protein (GFP) genes in rat organotypic hippocampal slice cultures. Monitoring of GFP fluorescence and immuno-histochemical staining for beta-galactosidase showed that the expression of the transferred genes was widespread in the glial cells and neurons of CA1, CA3/4, and dentate gyrus regions. Immunoblot analyses showed that the expression of gamma-galactosidase and GFP was maximal about 48 h after infection of hippocampal slices with the adenovirus vector and the expression levels were maintained for several weeks. Also, immunoblot analyses showed no significant differences in the MAP-2 and glial fibrillary acidic protein levels in the adenovirus vector infected and uninfected hippocampal slices. In addition, we found that the infection of hippocampal slices with the adenovirus vector caused no significant increase in the induction of heat shock protein (HSP)-70 and showed no change in their electrophysiological properties as measured by stable field synaptic potentials in CA1 region and its reactivity to high frequency stimulation. Our data suggest that this adenovirus vector can be exploited to transfer multiple genes into neurons and may have implications for developing strategies for gene therapy.

Heat shock protein-based therapeutic strategies against human immunodeficiency virus type 1 infection

Heat shock proteins (hsps) and cyclophilins (CypA) are intracellular chaperone molecules that facilitate protein folding and assembly. These proteins are selectively expressed in cells following exposure to a range of stress stimuli, including viral infection. Hsp species are highly immunogenic, eliciting humoral, cytotoxic T lymphocyte (CTL), and natural killer (NK) cell responses against viruses, tumours, and infectious diseases. This review discusses the roles of stress proteins in immunity and viral life cycles, vis-à-vis the development of Hsp-based therapeutic strategies against human immunodeficiency virus type-1 (HIV-1) infection. Cumulative findings are cited implicating the requirement of CypA in HIV-1 replication and formation of infectious virions. Studies by our group show the upregulated expression of hsp27 and hsp70 during single-cycle HIV infections. These species redistribute to the cell surface following HIV-infection and heat stress, serving as targets for NK and antibody-dependent cellular cytotoxicity. Co-immunoprecipitation and Western blot studies show that hsp27, hsp70, and hsp78 complex with HIV-1 viral proteins intracellularly. Hsp70, hsp56, and CypA are assembled into HIV-1 virions. The ability of hsps to interact with HIV-1 viral proteins, combined with their inherent adjuvant and immunogenic properties, indicates that hsps may serve as vehicles for antigen delivery and the design of vaccines against acquired immunodeficiency syndrome.

Sugar transport and glut transporter expression in a variety of human immunodeficiency virus-1 (HIV-1) chronically infected target cell lines

In this study, sugar transport and the cellular content of the human Glut 1 and 3 glucose transporters were ascertained in uninfected and chronically HIV-infected Jurkat and H9 cell lines (T-cell lines) and U937 cells (a promonocytic cell line). Sugar transport was determined by monitoring 2-deoxy glucose uptake (2DG) and glut transporter content was determined by Western analysis. Although 'acute' HIV infection of H9 cells led to increased cellular transport activity and Glut 3 transporter content, chronic HIV infection exhibited no significant differences in sugar transport in any of the cell types investigated whether log or stationary phase cultures were employed. When uninfected and chronically HIV-infected cell lines were compared, all cell lines expressed the Glut 1 transporter, however, significant differences in Glut 1 transporter content were not observed. The Glut 3 transporter which could only be detected in the H9 cell line exhibited no differences in Glut 3 content in uninfected or chronically HIV-infected cells (2.1 +/- 0.6 versus 3.8 +/- 2.1 x 10(-3) arbitrary units/microgram protein). A trend towards lower amino acid uptake was seen in the chronically HIV-infected cells but this was not significantly different from uninfected cell cultures. The data indicate that: (1) glucose transport and the Glut 1 and 3 transporters are not increased in cells chronically infected with HIV-1 and (2) the expression of the Glut 3 sugar transporters is not the same in all target cells.

Differential cellular distribution and dynamics of HSP70, cyclooxygenase-2, and c-Fos in the rat brain after transient focal ischemia or kainic acid

Cerebral ischemia and also excitotoxicity induce the expression of 72,000 mol. wt heat shock protein (Hsp70), c-Fos, and cyclooxygenase-2. In the present work we have examined whether Hsp70, c-Fos and cyclooxygenase-2 are expressed by the same cells in the rat brain at 6, 12 and 24 h following transient focal ischemia or kainic acid administration, by means of single and double immunohistochemistry. At 6 h after kainic acid, some co-localization of Hsp70 with c-Fos and cyclooxygenase-2 was seen in pyramidal hippocampal neurons and superficial cortical layers, however by 24 h such colocalization became rare within the cortex but was partially maintained in the hippocampus. Cyclooxygenase-2 was seen in many neurons that were also immunoreactive for c-Fos in superficial cortical layers, dentate gyrus and pyramidal cell layer of the hippocampus from 6 h after kainic acid. Co-localization of cyclooxygenase-2 and c-Fos was also observed in superficial cortical layers within the ipsilateral hemisphere at 6 h following focal ischemia. Also, some co-localization of Hsp70 with c-Fos and cyclooxygenase-2 was seen at this time. However, by 24 h cyclooxygenase-2 and c-Fos-immunoreactive cells were restricted to perifocal regions, and only a very limited co-localization with Hsp70 was seen in perifocal neurons located in the border of the penumbra-like area that surrounds the ischemic core and is strongly immunoreactive for Hsp70. This study shows a selective and dynamic cellular expression of inducible proteins following either ischemia or kainic acid, with a remarkable neuronal co-localization of c-Fos and cyclooxygenase-2. The results suggest that, first, stimuli underlying neuronal c-Fos expression can also lead to the induction of cyclooxygenase-2; second, transient co-localization of Hsp70 and c-Fos can take place in non-vulnerable neurons; and finally, expression of c-Fos, cyclooxygenase-2, and/or Hsp70 at a given time-point is part of the response to altered environmental conditions and can be related to the particular cellular sensitivity rather than the pathological outcome.

Antiviral activity of cyclopentenone prostanoids

Cyclopentenone prostanoids inhibit virus replication by turning on an intracellular defence response that involves the induction of cytoprotective heat-shock proteins, the modification of viral glycoprotein maturation and the control of NF-kappa B activation. These molecules represent an interesting model for the development of novel antiviral drugs that can affect different targets during the virus life cycle.

Inhibition of nuclear factor kappa B by prostaglandin A1: an effect associated with heat shock transcription factor activation

Prostaglandins (PGs) function as intracellular signal mediators in the regulation of a variety of physiological and pathological processes, including inflammation and immune responses. Cyclopentenone PGs are characterized by antiviral activity against several viruses, including human immunodeficiency virus type 1 (HIV-1), and by the ability to induce heat shock protein expression through activation of the heat shock transcription factor. Here we report that PGA1 is a potent inhibitor of nuclear factor-kappa B (NF-kappa B) activation in human cells and of NF-kappa B-dependent HIV-1 transcription in long terminal repeat-chloramphenicol acetyl-transferase transient transfection experiments. PGA1 acts by inhibiting phosphorylation and preventing degradation of the NF-kappa B inhibitor I kappa B-alpha. Inhibition does not require protein synthesis, is dependent on the presence of a reactive cyclopentenonic moiety, and is associated with heat shock transcription factor activation. Because NF-kappa B is critically involved in the activation of immunoregulatory and viral genes, inhibition of its activity could be a major component of the immunosuppressive and antiviral activity of PGs.

2-Cyclopenten-1-one, a new inducer of heat shock protein 70 with antiviral activity

The cytoprotective role of heat shock proteins (HSP) described in variety of human diseases, including ischemia, inflammation, and infection, suggests new therapeutic strategies relying upon the development of drugs that selectively turn on heat shock genes. Cyclopentenone prostaglandins, which contain an alpha, beta-unsaturated carbonyl group in the cyclopentane ring and possess antiviral activity against several RNA and DNA viruses, were shown to function as signal for HSP synthesis in a nonstressful situation in a variety of mammalian cells. We now report that 2-cyclopenten-1-one selectively induces the expression of the 70-kDa HSP (HSP70) in human cells, through cycloheximide-sensitive activation of heat shock transcription factor 1 (HSF1). The alpha, beta-unsaturated carbonyl group is the key structure triggering HSF1 activation. Induction is associated with antiviral activity during infection with vesicular stomatitis virus. These results identify the molecular structure of natural prostaglandins responsible for HSF1 activation and open new perspectives in the search for novel antiviral and cytoprotective drugs.