Differential expression of stress proteins in human adult astrocytes in response to cytokines

Putative Roles and Therapeutic Potential of the Chaperone System in Amyotrophic Lateral Sclerosis and Multiple Sclerosis

The putative pathogenic roles and therapeutic potential of the chaperone system (CS) in amyotrophic lateral sclerosis (ALS) and multiple sclerosis (MS) are reviewed to provide a bibliographic and conceptual platform for launching research on the diagnostic and therapeutic applications of CS components. Various studies suggest that dysfunction of the CS contributes to the pathogenesis of ALS and MS, and here, we identify some of the implicated CS members. The physiology and pathophysiology of the CS members can be properly understood if they are studied or experimentally or clinically manipulated for diagnostic or therapeutic purposes, bearing in mind that they belong to a physiological system with multiple interacting and dynamic components, widespread throughout the body, intra- and extracellularly. Molecular chaperones, some called heat shock protein (Hsp), are the chief components of the CS, whose canonical functions are cytoprotective. However, abnormal chaperones can be etiopathogenic factors in a wide range of disorders, chaperonopathies, including ALS and MS, according to the data reviewed. Chaperones typically form teams, and these build functional networks to maintain protein homeostasis, the canonical role of the CS. However, members of the CS also display non-canonical functions unrelated to protein homeostasis. Therefore, chaperones and other members of the CS, if abnormal, may disturb not only protein synthesis, maturation, and migration but also other physiological processes. Thus, in elucidating the role of CS components in ALS and MS, one must look at protein homeostasis abnormalities and beyond, following the clues emerging from the works discussed here.

Introducing Molecular Chaperones into the Causality and Prospective Management of Autoimmune Hepatitis

Molecular chaperones influence the immunogenicity of peptides and the activation of effector T cells, and their pathogenic roles in autoimmune hepatitis are unclear. Heat shock proteins are pivotal in the processing and presentation of peptides that activate CD8+ T cells. They can also induce regulatory B and T cells and promote immune tolerance. Tapasin and the transporter associated with antigen processing-binding protein influence the editing and loading of high-affinity peptides for presentation by class I molecules of the major histocompatibility complex. Their over-expression could enhance the autoimmune response, and their deficiency could weaken it. The lysosome-associated membrane protein-2a isoform in conjunction with heat shock cognate 70 supports the importation of cytosolic proteins into lysosomes. Chaperone-mediated autophagy can then process the peptides for activation of CD4+ T cells. Over-expression of autophagy in T cells may also eliminate negative regulators of their activity. The human leukocyte antigen B-associated transcript three facilitates the expression of class II peptide receptors, inhibits T cell apoptosis, prevents T cell exhaustion, and sustains the immune response. Immunization with heat shock proteins has induced immune tolerance in experimental models and humans with autoimmune disease by inducing regulatory T cells. Therapeutic manipulation of other molecular chaperones may promote T cell exhaustion and induce tolerogenic dendritic cells. In conclusion, molecular chaperones constitute an under-evaluated family of ancillary proteins that could affect the occurrence, severity, and outcome of autoimmune hepatitis. Clarification of their contributions to the immune mechanisms and clinical activity of autoimmune hepatitis could have therapeutic implications.

The Role of Small Heat Shock Proteins in Protein Misfolding Associated Motoneuron Diseases

Motoneuron diseases (MNDs) are neurodegenerative conditions associated with death of upper and/or lower motoneurons (MNs). Proteostasis alteration is a pathogenic mechanism involved in many MNDs and is due to the excessive presence of misfolded and aggregated proteins. Protein misfolding may be the product of gene mutations, or due to defects in the translation process, or to stress agents; all these conditions may alter the native conformation of proteins making them prone to aggregate. Alternatively, mutations in members of the protein quality control (PQC) system may determine a loss of function of the proteostasis network. This causes an impairment in the capability to handle and remove aberrant or damaged proteins. The PQC system consists of the degradative pathways, which are the autophagy and the proteasome, and a network of chaperones and co-chaperones. Among these components, Heat Shock Protein 70 represents the main factor in substrate triage to folding, refolding, or degradation, and it is assisted in this task by a subclass of the chaperone network, the small heat shock protein (sHSPs/HSPBs) family. HSPBs take part in proteostasis by bridging misfolded and aggregated proteins to the HSP70 machinery and to the degradative pathways, facilitating refolding or clearance of the potentially toxic proteins. Because of its activity against proteostasis alteration, the chaperone system plays a relevant role in the protection against proteotoxicity in MNDs. Here, we discuss the role of HSPBs in MNDs and which HSPBs may represent a valid target for therapeutic purposes.

Mitochondrial chaperones in human health and disease

Molecular chaperones are a family of proteins that maintain cellular protein homeostasis through non-covalent peptide folding and quality control mechanisms. The chaperone proteins found within mitochondria play significant protective roles in mitochondrial biogenesis, quality control, and stress response mechanisms. Defective mitochondrial chaperones have been implicated in aging, neurodegeneration, and cancer. In this review, we focus on the two most prominent mitochondrial chaperones: mtHsp60 and mtHsp70. These proteins demonstrate different cellular localization patterns, interact with different targets, and have different functional activities. We discuss the structure and function of these prominent mitochondrial chaperone proteins and give an update on newly discovered regulatory mechanisms and disease implications.

The Pathophysiological Role of Heat Shock Response in Autoimmunity: A Literature Review

Within the last two decades, there has been increasing evidence that heat-shock proteins can have a differential influence on the immune system. They can either provoke or ameliorate immune responses. This review focuses on outlining the stimulatory as well as the inhibitory effects of heat-shock proteins 27, 40, 70, 65, 60, and 90 in experimental and clinical autoimmune settings.

Regional Differences in Heat Shock Protein 25 Expression in Brain and Spinal Cord Astrocytes of Wild-Type and SOD1 G93A Mice

Heterogeneity of glia in different CNS regions may contribute to the selective vulnerability of neuronal populations in neurodegenerative conditions such as amyotrophic lateral sclerosis (ALS). Here, we explored regional variations in the expression of heat shock protein 25 in glia under conditions of acute and chronic stress. Hsp27 (Hsp27; murine orthologue: Hsp25) fulfils a number of cytoprotective functions and may therefore be a possible therapeutic target in ALS. We identified a subpopulation of astrocytes in primary murine mixed glial cultures that expressed Hsp25. Under basal conditions, the proportion of Hsp25-positive astrocytes was twice as high in spinal cord cultures than in cortical cultures. To explore the physiological role of the elevated Hsp25 expression in spinal cord astrocytes, we exposed cortical and spinal cord glia to acute stress, using heat stress and pro-inflammatory stimuli. Surprisingly, we observed no stress-induced increase in Hsp25 expression in either cortical or spinal cord astrocytes. Similarly, exposure to endogenous stress, as modelled in glial cultures from SOD1 G93A-ALS mice, did not increase Hsp25 expression above that observed in astrocytes from wild-type mice. In vivo, Hsp25 expression was greater under conditions of chronic stress present in the spinal cord of SOD1 G93A mice than in wild-type mice, although this increase in expression is likely to be due to the extensive gliosis that occurs in this model. Together, these results show that there are differences in the expression of Hsp25 in astrocytes in different regions of the central nervous system, but Hsp25 expression is not upregulated under acute or chronic stress conditions.

HSPA1L Enhances Cancer Stem Cell-Like Properties by Activating IGF1Rβ and Regulating β-Catenin Transcription

Studies have shown that cancer stem cells (CSCs) are involved in resistance and metastasis of cancer; thus, therapies targeting CSCs have been proposed. Here, we report that heat shock 70-kDa protein 1-like (HSPA1L) is partly involved in enhancing epithelial–mesenchymal transition (EMT) and CSC-like properties in non-small cell lung cancer (NSCLC) cells. Aldehyde dehydrogenase 1 (ALDH1) is considered a CSC marker in some lung cancers. Here, we analyzed transcriptional changes in genes between ALDH1high and ALDH1low cells sorted from A549 NSCLC cells and found that HSPA1L was highly expressed in ALDH1high cells. HSPA1L played two important roles in enhancing CSC-like properties. First, HSPA1L interacts directly with IGF1Rβ and integrin αV to form a triple complex that is involved in IGF1Rβ activation. HSPA1L/integrin αV complex-associated IGF1Rβ activation intensified the EMT-associated cancer stemness and γ-radiation resistance through its downstream AKT/NF-κB or AKT/GSK3β/β-catenin activation pathway. Secondly, HSPA1L was also present in the nucleus and could bind directly to the promoter region of β-catenin to function as a transcription activator of β-catenin, an important signaling protein characterizing CSCs by regulating ALDH1 expression. HSPA1L may be a novel potential target for cancer treatment because it both enhances IGF1Rβ activation and regulates γβ-catenin transcription, accumulating CSC-like properties.

Heat shock protein 60 (HSP60) modulates adiponectin signaling by stabilizing adiponectin receptor

Adiponectin, an adipokine produced and secreted by adipocytes, is involved in regulating the development and progression of insulin resistance, diabetes, and diabetic complications. Heat shock protein 60 (HSP60) is a molecular chaperone, most commonly presenting in mitochondria and participating in the maintenance of protein homeostasis. Accumulating studies have demonstrated that the elevated circulating HSP60 and the decreased intracellular HSP60 are closely associated with diabetic complications such as diabetic cardiomyopathy. However, the underlying mechanism remains poorly understood. In the present study, we reported that HSP60 interacted directly with adiponectin receptors. Its abundance was positively associated with adiponectin action. Furthermore, HSP60 depletion markedly mitigated the protective impacts of adiponectin on high glucose-induced oxidative stress and cell apoptosis in rat cardiac H9c2 cells. In addition, HSP60 knockdown significantly enhanced proteasome activity leading to the degradation of adiponectin receptor 1. Taken together, we showed for the first time that HSP60 interacted with adiponectin receptors and mediated adiponectin signaling through stabilizing adiponectin receptor. This in vitro study also provides an alternative explanation for mechanism by which adiponectin exerts its action.

Alpha B-Crystallin Overexpression Protects Oligodendrocyte Precursor Cells Against Oxidative Stress-Induced Apoptosis Through the Akt Pathway

Alpha B-crystallin (aBC), a member of the small heat shock protein family, is expressed in mature oligodendrocytes (mOLs), but not in oligodendrocyte precursor cells (OPCs). Our previous study found that the survival rate of OPCs was lower than that of mOLs under oxidative stress, suggesting that aBC may play a protective role in mOLs. In the present study, we investigated the effects of aBC overexpression on oxidative stress-induced cell injury in OPCs and examined the underlying mechanisms. We observed that the survival rates of aBC-overexpressed OPCs were significantly higher than those of control cells under oxidative stress induced by hydrogen peroxide. Akt activities were significantly suppressed by oxidative stress in control OPCs, but not in aBC-overexpressed OPCs. The expressions of Bax and cleaved caspase-3 were decreased, whereas Bcl-2 expression was increased in aBC-overexpressed OPCs under oxidative stress. These findings suggest that low Akt activity in OPCs due to aBC deficiency may cause high susceptibility of OPCs to oxidative stress. The findings may provide new insights into the implication of OPCs in demyelinating diseases.

Myelin Pathology: Involvement of Molecular Chaperones and the Promise of Chaperonotherapy

The process of axon myelination involves various proteins including molecular chaperones. Myelin alteration is a common feature in neurological diseases due to structural and functional abnormalities of one or more myelin proteins. Genetic proteinopathies may occur either in the presence of a normal chaperoning system, which is unable to assist the defective myelin protein in its folding and migration, or due to mutations in chaperone genes, leading to functional defects in assisting myelin maturation/migration. The latter are a subgroup of genetic chaperonopathies causing demyelination. In this brief review, we describe some paradigmatic examples pertaining to the chaperonins Hsp60 (HSPD1, or HSP60, or Cpn60) and CCT (chaperonin-containing TCP-1). Our aim is to make scientists and physicians aware of the possibility and advantages of classifying patients depending on the presence or absence of a chaperonopathy. In turn, this subclassification will allow the development of novel therapeutic strategies (chaperonotherapy) by using molecular chaperones as agents or targets for treatment.

Phosphorylation of αB-crystallin supports reactive astrogliosis in demyelination

The small heat shock protein αB-crystallin (CRYAB) has been implicated in multiple sclerosis (MS) pathogenesis. Earlier studies have indicated that CRYAB inhibits inflammation and attenuates clinical disease when administered in the experimental autoimmune encephalomyelitis model of MS. In this study, we evaluated the role of CRYAB in primary demyelinating events. Using the cuprizone model of demyelination, a noninflammatory model that allows the analysis of glial responses in MS, we show that endogenous CRYAB expression is associated with increased severity of demyelination. Moreover, we demonstrate a strong correlation between the expression of CRYAB and the extent of reactive astrogliosis in demyelinating areas and in in vitro assays. In addition, we reveal that CRYAB is differentially phosphorylated in astrocytes in active demyelinating MS lesions, as well as in cuprizone-induced lesions, and that this phosphorylation is required for the reactive astrocyte response associated with demyelination. Furthermore, taking a proteomics approach to identify proteins that are bound by the phosphorylated forms of CRYAB in primary cultured astrocytes, we show that there is clear differential binding of protein targets due to the specific phosphorylation of CRYAB. Subsequent Ingenuity Pathway Analysis of these targets reveals implications for intracellular pathways and biological processes that could be affected by these modifications. Together, these findings demonstrate that astrocytes play a pivotal role in demyelination, making them a potential target for therapeutic intervention, and that phosphorylation of CRYAB is a key factor supporting the pathogenic response of astrocytes to oligodendrocyte injury.

Serum Heat Shock Protein Levels and the Relationship of Heat Shock Proteins with Various Parameters in Chronic Obstructive Pulmonary Disease Patients

OBJECTIVES

Chronic Obstructive Pulmonary Disease (COPD) is accompanied by increased cellular stress and inflammation. Most of the Heat Shock Proteins (HSPs) have strong cytoprotective effects. The role of HSPs in COPD pathogenesis has not determined completely. We investigated the serum level of HSPs in COPD patients, smokers without COPD and healthy non-smoking controls. Also, we evaluated the relationship of HSPs with various parameters (inflammatory, oxidative, functional status, quality of life) in COPD patients.

MATERIAL AND METHODS

The levels of stress protein (HSP27, HSP70, HSP60, HSP90, CyPA), interleukin-6, C-reactive protein and malondialdehyde were measured in 16 healthy non-smoker, 14 smokers without COPD and 50 patients with stable COPD. Pulmonary function tests (PFT) and arterial blood gases parameters were measured. Health Related Quality of Life was evaluated and exercise capacity was measured with 6 minute walking test.

RESULTS

Only HSP27 levels was significantly higher in COPD patients when compared with both healthy non-smoker and smokers without COPD (for both, p< 0.001). There was a weak-moderate negative correlation between serum levels of HSP27 and PFT parameters and between HSP27 levels and PaO2. Serum levels of HSP27 showed a weak-moderate positive correlation with symptom, activity and total scores. Subjects evaluated only smokers without COPD and patients with COPD; HSP27 had an area under the curve (AUC) in the receiver operating characteristic (ROC) curve of 0.819 (0.702-0.935; 95% CI; p= 0.000).

CONCLUSION

Increased serum levels of HSP27 was found in COPD patients and our results showed sensitivity and specificity of serum HSP27 as diagnostic markers for COPD.

HSP60 plays a regulatory role in IL-1β-induced microglial inflammation via TLR4-p38 MAPK axis

Background

IL-1β, also known as “the master regulator of inflammation”, is a potent pro-inflammatory cytokine secreted by activated microglia in response to pathogenic invasions or neurodegeneration. It initiates a vicious cycle of inflammation and orchestrates various molecular mechanisms involved in neuroinflammation. The role of IL-1β has been extensively studied in neurodegenerative disorders; however, molecular mechanisms underlying inflammation induced by IL-1β are still poorly understood. The objective of our study is the comprehensive identification of molecular circuitry involved in IL-1β-induced inflammation in microglia through protein profiling.

Methods

To achieve our aim, we performed the proteomic analysis of N9 microglial cells with and without IL-1β treatment at different time points. Expression of HSP60 in response to IL-1β administration was checked by quantitative real-time PCR, immunoblotting, and immunofluorescence. Interaction of HSP60 with TLR4 was determined by co-immunoprecipitation. Inhibition of TLR4 was done using TLR4 inhibitor to reveal its effect on IL-1β-induced inflammation. Further, effect of HSP60 knockdown and overexpression were assessed on the inflammation in microglia. Specific MAPK inhibitors were used to reveal the downstream MAPK exclusively involved in HSP60-induced inflammation in microglia.

Results

Total 21 proteins were found to be differentially expressed in response to IL-1β treatment in N9 microglial cells. In silico analysis of these proteins revealed unfolded protein response as one of the most significant molecular functions, and HSP60 turned out to be a key hub molecule. IL-1β induced the expression as well as secretion of HSP60 in extracellular milieu during inflammation of N9 cells. Secreted HSP60 binds to TLR4 and inhibition of TLR4 suppressed IL-1β-induced inflammation to a significant extent. Our knockdown and overexpression studies demonstrated that HSP60 increases the phosphorylation of ERK, JNK, and p38 MAPKs in N9 cells during inflammation. Specific inhibition of p38 by inhibitors suppressed HSP60-induced inflammation, thus pointed towards the major role of p38 MAPK rather than ERK1/2 and JNK in HSP60-induced inflammation. Furthermore, silencing of upstream modulator of p38, i.e., MEK3/6 also reduced HSP60-induced inflammation.

Conclusions

IL-1β induces expression of HSP60 in N9 microglial cells that further augments inflammation via TLR4-p38 MAPK axis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0486-x) contains supplementary material, which is available to authorized users.

Small heat shock proteins are induced during multiple sclerosis lesion development in white but not grey matter

Introduction

The important protective role of small heat-shock proteins (HSPs) in regulating cellular survival and migration, counteracting protein aggregation, preventing apoptosis, and regulating inflammation in the central nervous system is now well-recognized. Yet, their role in the neuroinflammatory disorder multiple sclerosis (MS) is largely undocumented. With the exception of alpha B-crystallin (HSPB5), little is known about the roles of small HSPs in disease.

Results

Here, we examined the expression of four small HSPs during lesion development in MS, focussing on their cellular distribution, and regional differences between white matter (WM) and grey matter (GM). It is well known that MS lesions in these areas differ markedly in their pathology, with substantially more intense blood-brain barrier damage, leukocyte infiltration and microglial activation typifying WM but not GM lesions.

We analysed transcript levels and protein distribution profiles for HSPB1, HSPB6, HSPB8 and HSPB11 in MS lesions at different stages, comparing them with normal-appearing brain tissue from MS patients and non-neurological controls. During active stages of demyelination in WM, and especially the centre of chronic active MS lesions, we found significantly increased expression of HSPB1, HSPB6 and HSPB8, but not HSPB11. When induced, small HSPs were exclusively found in astrocytes but not in oligodendrocytes, microglia or neurons. Surprisingly, while the numbers of astrocytes displaying high expression of small HSPs were markedly increased in actively demyelinating lesions in WM, no such induction was observed in GM lesions. This difference was particularly obvious in leukocortical lesions covering both WM and GM areas.

Conclusions

Since induction of small HSPs in astrocytes is apparently a secondary response to damage, their differential expression between WM and GM likely reflects differences in mediators that accompany demyelination in either WM or GM during MS. Our findings also suggest that during MS, cortical structures fail to benefit from the protective actions of small HSPs.

Electronic supplementary material

The online version of this article (doi:10.1186/s40478-015-0267-2) contains supplementary material, which is available to authorized users.

HSPA12B regulates SSeCKS-mediated astrocyte inflammatory activation in neuroinflammation

Reactive astrocytosis has been considered either beneficial or detrimental effection in neuroinflammatory disease. HSPA12B, a new member belongs to the 70-kDa family of heat shock proteins (HSP70) which could modulate inflammatory response, also shows an connection with the astrocyte activation. Recently, it was reported that Src-Suppressed-C Kinase Substrate (SSeCKS) was detected in heat shock protein A12B (HSPA12B) interacting proteins using a yeast 2-hybrid system. SSeCKS, a major Lipopolysaccharide (LPS) response protein, has been involved in regulating astrocyte activation via production of proinflammatory factor in CNS inflammation. In this study, we found HSPA12B might regulate the expression and activity of SSeCKS to promote astrocyte inflammatory activation and release of inflammatory mediators, such as TNF-α and IL-1β in spinal cord primary astroglial cultures exposed to LPS treatment. The promoting mechanism of interaction between HSPA12B and SSeCKS on LPS-induced astrocyte activation was mediated via the activation of JNK and p38 signaling pathways but not ERK1/2 MAPK signaling pathway. HSPA12B binded to SSeCKS via its both N terminus consisted of amino acids 1-330 and C terminus consisted of amino acids 1278-1596. And, in vivo, we confirmed the interaction between HSPA12B and SSeCKS of astrocyte activation in the pathogenesis of EAE. The regulatory mechanisms of HSPA12B-SSeCKS interaction may possibly be the key therapeutic strategy of neuroinflammatory disease.

Replication-Competent Controlled Herpes Simplex Virus

We present the development and characterization of a replication-competent controlled herpes simplex virus 1 (HSV-1). Replication-essential ICP4 and ICP8 genes of HSV-1 wild-type strain 17syn+ were brought under the control of a dually responsive gene switch. The gene switch comprises (i) a transactivator that is activated by a narrow class of antiprogestins, including mifepristone and ulipristal, and whose expression is mediated by a promoter cassette that comprises an HSP70B promoter and a transactivator-responsive promoter and (ii) transactivator-responsive promoters that drive the ICP4 and ICP8 genes. Single-step growth experiments in different cell lines demonstrated that replication of the recombinant virus, HSV-GS3, is strictly dependent on an activating treatment consisting of administration of a supraphysiological heat dose in the presence of an antiprogestin. The replication-competent controlled virus replicates with an efficiency approaching that of the wild-type virus from which it was derived. Essentially no replication occurs in the absence of activating treatment or if HSV-GS3-infected cells are exposed only to heat or antiprogestin. These findings were corroborated by measurements of amounts of viral DNA and transcripts of the regulated ICP4 gene and the glycoprotein C (gC) late gene, which was not regulated. Similar findings were made in experiments with a mouse footpad infection model.

IMPORTANCE

The alphaherpesviruses have long been considered vectors for recombinant vaccines and oncolytic therapies. The traditional approach uses vector backbones containing attenuating mutations that restrict replication to ensure safety. The shortcoming of this approach is that the attenuating mutations tend to limit both the immune presentation and oncolytic properties of these vectors. HSV-GS3 represents a novel type of vector that, when activated, replicates with the efficiency of a nonattenuated virus and whose safety is derived from deliberate, stringent regulation of multiple replication-essential genes. By directing activating heat to the region of virus administration, replication is strictly confined to infected cells within this region. The requirement for antiprogestin provides an additional level of safety, ensuring that virus replication cannot be triggered inadvertently. Replication-competent controlled vectors such as HSV-GS3 may have the potential to be superior to conventional attenuated HSV vaccine and oncolytic vectors without sacrificing safety.

Control of autoimmune CNS inflammation by astrocytes

Multiple sclerosis is a neurologic disease caused by immune cell infiltration into the central nervous system, resulting in gray and white matter inflammation, progressive demyelination, and neuronal loss. Astrocytes, the most abundant cell population in the central nervous system (CNS), have been considered inert scaffold or housekeeping cells for many years. However, recently, it has become clear that this cell population actively modulates the immune response in the CNS at multiple levels. While being exposed to a plethora of cytokines during ongoing autoimmune inflammation, astrocytes modulate local CNS inflammation by secreting cytokines and chemokines, among other factors. This review article gives an overview of the most recent understanding about cytokine networks operational in astrocytes during autoimmune neuroinflammation and highlights potential targets for immunomodulatory therapies for multiple sclerosis.

Crystallins and neuroinflammation: The glial side of the story

BACKGROUND

There is an abundance of evidence to support the association of damaging neuroinflammation and neurodegeneration across a multitude of diseases. One of the links between these pathological phenomena is the role of chaperone proteins as both neuroprotective and immune-regulatory agents.

SCOPE OF REVIEW

Chaperone proteins are highly expressed at sites of neuroinflammation both in glial cells and in the injured neurons that initiate the immune response. For this reason, the use of chaperones as treatment for various diseases associated with neuroinflammation is a highly active area of investigation. This review explores the various ways that the small heat shock protein chaperones, α-crystallins, can affect glial cell function with a specific focus on their implication in the inflammatory response associated with neurodegenerative disorders, and their potential as therapeutic treatment.

MAJOR CONCLUSIONS

Although the mechanisms are still under investigation, a clear link has now been established between alpha-crystallins and neuroinflammation, especially through their roles in microglial and macroglial cells. Interestingly, similar to inflammation in itself, crystallins can have a beneficial or detrimental impact on the CNS based on the context and duration of the condition.

GENERAL SIGNIFICANCE

Overall this review points out the novel roles that chaperones such as alpha-crystallins can play outside of the classical protein folding pathways, and their potential in the development of new therapies for the treatment of neuroinflammatory/neurodegenerative diseases. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.

Analysis of IL-6, STAT3 and HSPA1L gene polymorphisms in anti-tuberculosis drug-induced hepatitis in a nested case-control study

OBJECTIVES

To investigate the association of IL-6, STAT3 and HSPA1L polymorphisms with the risk of anti-tuberculosis drug-induced hepatitis (ATDH) in Chinese Han population.

METHODS

The study was designed as a nested case-control study within a prospective cohort. Each case was matched with four controls by sex, age at baseline (±5 years), treatment history, disease severity, drug dosage and place of sample collection. Genetic polymorphisms of IL-6, STAT3 and HSPA1L were determined blindly by TaqMan single-nucleotide polymorphism (SNP) genotyping assay. Odds ratio (OR) with 95% confidence intervals (CIs) was estimated by conditional logistic regression model to measure the association between selected SNPs and the risk of ATDH.

RESULTS

A total of 89 incident ATDH cases and 356 ATDH-free controls were genotyped for IL-6 (rs2066992, rs2069837, rs1524107), STAT3 (rs1053004, rs1053023, rs1053005) and HSPA1L (rs2227956). In genotype analysis, no significant difference was observed in genotypes frequencies of the seven selected SNPs between case and control group after Bonferroni correction. In haplotype analysis, carriers with STAT3 GAT and AGC (rs1053023-rs1053005-rs1053004) haplotypes had a significantly higher risk of ATDH compared with wild-type haplotype (P<0.0001).

CONCLUSION

This study suggested that genetic variants of STAT3 might contribute to ATDH susceptibility in Chinese Han population. Studies in larger, varied populations are required to confirm these findings.

Up-regulation of inducible heat shock protein-70 expression in multiple sclerosis patients

Inducible heat shock protein (HSP)70 (HSP70-1A and HSP70-1B proteins) is a chaperone responsible for assisting proper protein folding. Following stress conditions, HSP70 is highly up-regulated to mediate cytoprotective functions. In addition, HSP70 is able to trigger innate and adaptive immune responses that promote the immune recognition of antigens and to act as a cytokine when it is released. The data in the literature are controversial with regard to expression studies in peripheral blood mononuclear cells (PBMCs). In the present study, we aimed to examine if alterations of HSP70-1A/B expression are involved in the autoimmune pathogenesis of multiple sclerosis (MS). We determined both mRNA and protein expression in PBMCs of MS patients and healthy donors (HDs). We found a baseline increased expression of the HSPA1A gene in PBMCs from MS patients compared with HDs. Gene expression findings were associated with an increased protein expression of HSP70-1A/B in T lymphocytes (CD4+ and CD8+) and monocytes from MS patients under basal conditions that may reflect the immunological activation occurring in MS patients. We also provided evidence that heat shock (HS) stimulus induced HSP70-1A/B protein expression in HDs and MS patients, and that HS-induced HSP70-1A/B protein expression in monocytes correlated with the number of T2 lesions at baseline in MS patients. However, after lipopolysaccharide inflammatory stimulus, monocytes from MS patients failed to induce HSP70-1A/B protein expression. Our data hint at altered immune responses in MS and may indicate either a state of chronic stress or increased vulnerability to physiological immune responses in MS patients.

Heat shock protein 70: roles in multiple sclerosis

Heat shock proteins (HSP) have long been considered intracellular chaperones that possess housekeeping and cytoprotective functions. Consequently, HSP overexpression was proposed as a potential therapy for neurodegenerative diseases characterized by the accumulation or aggregation of abnormal proteins. Recently, the discovery that cells release HSP with the capacity to trigger proinflammatory as well as immunoregulatory responses has focused attention on investigating the role of HSP in chronic inflammatory autoimmune diseases such as multiple sclerosis (MS). To date, the most relevant HSP is the inducible Hsp70, which exhibits both cytoprotectant and immunoregulatory functions. Several studies have presented contradictory evidence concerning the involvement of Hsp70 in MS or experimental autoimmune encephalomyelitis (EAE), the MS animal model. In this review, we dissect the functions of Hsp70 and discuss the controversial data concerning the role of Hsp70 in MS and EAE.

Heat shock protein 60 as a mediator of adipose tissue inflammation and insulin resistance

The stress protein heat shock protein 60 (Hsp60) induces secretion of proinflammatory mediators from murine adipocytes. This study aimed to study Hsp60 as a mediator of adipose tissue inflammation and skeletal muscle cell (SkMC) insulin sensitivity and to quantify plasma Hsp60 concentrations in lean and obese individuals. Regulation of Hsp60 release and Hsp60-induced cytokine secretion and signaling was measured in human adipocytes and SkMCs. Adipocytes exhibited higher Hsp60 release than preadipocytes and SkMCs, which was further stimulated by cytokines and Toll-like receptor (TLR)-4 activation. Hsp60 activated extracellular signal-related kinase (ERK)-1/2, Jun NH(2)-terminal kinase (JNK), p38, nuclear factor (NF)-κB, and impaired insulin-stimulated Akt phosphorylation in adipocytes. Furthermore, Hsp60 stimulated adipocytes to secrete tumor necrosis factor-α, interleukin (IL)-6, and IL-8. In SkMCs, Hsp60 activated ERK1/2, JNK, and NF-κB and inhibits insulin signaling and insulin-stimulated glucose uptake. SkMCs released IL-6, IL-8, and monocyte chemoattractant protein-1 on Hsp60 stimulation. Plasma Hsp60 was higher in obese males than in lean males and correlated positively with BMI, blood pressure, leptin, and homeostasis model assessment-insulin resistance. In summary, Hsp60 is released by human adipocytes, increased in plasma of obese humans, and induces insulin resistance. This is accompanied by activation of proinflammatory signaling in human adipocytes and SkMCs. Thus, Hsp60 might be a factor underlying adipose tissue inflammation and obesity-associated metabolic disorders.

Anti-inflammatory effects of β-sitosterol-β-D-glucoside from Trachelospermum jasminoides (Apocynaceae) in lipopolysaccharide-stimulated RAW 264.7 murine macrophages

Trachelospermum jasminoides (Apocynaceae) has pharmacological effects that include anti-inflammatory, anti-bacterial and anti-viral activities, which have been observed from various studies. Of these pharmacological effects, the anti-inflammatory capacity of compounds from T. jasminoides is not yet known exactly. In this study, we investigated the compound that can be used for the suppression of lipopolysacchaide (LPS) stimulated inflammatory responses in macrophages among the five isolated compounds. β-sitosterol-β-D-glucoside (1) was found to reduce nitric oxide (NO) production from LPS-induced RAW 264.7 cells the most. In addition, compound 1 strongly inhibited the interleukin 6 (IL-6) activities of stimulated macrophages. Treatment of RAW 264.7 cells with compound 1 reduced secretion of inflammatory elements including tumour necrosis factor - alpha (TNF-α) and interleukin 1 beta (IL-1β). Thus, compound 1 may be a useful candidate for the development of new drugs to treat endotoxemia and inflammation accompanied by the overproduction of NO.

Elevated HSP27 levels during attacks in patients with multiple sclerosis

OBJECTIVES

The small heat shock protein, HSP27, has been shown to have a more potent protective effect in the nervous system. However, there is limited information about the behavior of HSP27 in the course of multiple sclerosis (MS). Thus, we investigated the HSP27 levels during relapse and remission phases of MS.

MATERIALS AND METHODS

A total of 50 relapsing-remitting or secondary progressive MS patients and 45 age- and gender-matched controls without any systemic diseases were enrolled. HSP27 levels were serologically detected in serum samples of both controls and MS patients during acute attacks and after a minimum of 2 months of each individual attack.

RESULTS

The mean HSP27 level was 12.41 ± 18.21 ng/ml in the attack phase, 4.58 ± 4.75 ng/ml during remission, and 2.58 ± 3.88 ng/ml in control patients. The heat shock proteins (HSP) levels of MS patients in the attack phase were significantly higher than those obtained in the remission phase (P = 0.005). Moreover, HSP levels in the attack and remission phases of MS patients were also significantly higher when compared to controls (P = 0.001 and P = 0.03, respectively). While there was no correlation between HSP27 levels in the attack phase and age, disease duration, or expanded disability status scale scores (P = 0.69, P = 0.32, and P = 0.91, respectively), a positive correlation was observed between the HSP27 levels and the total attack number (P = 0.001).

CONCLUSIONS

Our findings revealed a marked elevation in HSP27 levels during the relapse phase. Therefore, it can be suggested that elevated HSP27 levels may guide in the accurate detection of an attack in patients with MS.

A proteomic analysis of PKCε targets in astrocytes: implications for astrogliosis

Astrocytes are glial cells in the central nervous system (CNS) that play key roles in brain physiology, controlling processes, such as neurogenesis, brain energy metabolism and synaptic transmission. Recently, immune functions have also been demonstrated in astrocytes, influencing neuronal survival in the course of neuroinflammatory pathologies. In this regard, PKCepsilon (PKCε) is a protein kinase with an outstanding role in inflammation. Our previous findings indicating that PKCε regulates voltage-dependent calcium channels as well as morphological stellation imply that this kinase controls multiple signalling pathways within astrocytes, including those implicated in activation of immune functions. The present study applies proteomics to investigate new protein targets of PKCε in astrocytes. Primary astrocyte cultures infected with an adenovirus that expresses constitutively active PKCε were compared with infection controls. Two-dimensional gel electrophoresis clearly detected 549 spots in cultured astrocytes, and analysis of differential protein expression revealed 18 spots regulated by PKCε. Protein identification by mass spectrometry (nano-LC-ESI-MS/MS) showed that PKCε targets molecules with heterogeneous functions, including chaperones, cytoskeletal components and proteins implicated in metabolism and signalling. These results support the notion that PKCε is involved in astrocyte activation; also suggesting that multiple astrocyte-dependent processes are regulated by PKCε, including those associated to neuroinflammation.

Regulation of lipopolysaccharide-induced inflammatory response by heat shock protein 27 in THP-1 cells

HSP27 is a member of the small HSP family which has been linked to different signaling pathways regulating critical cellular functions. But the role of HSP27 in LPS-induced inflammatory signaling pathways is still unclear. In the present study, both overexpression and RNA interference experiments indicated that HSP27 increased LPS-induced expression of iNOS and COX-2 and release of NO/PGE2 through enhancing NF-kappaB but not MAPK activation. The effects of HSP27 on LPS-induced iNOS/COX-2 expression and relative signaling cascade were closely related with the phosphorylation of HSP27. Further studies have shown that HSP27-regulated LPS-induced activation of NF-kappaB by interacting with TRAF6 and increasing the association of TRAF6-IKKgamma. This could be a probable mechanism by which HSP27 modulates LPS-induce inflammatory signaling pathways. Thus, HSP27 may play a potential role in regulating inflammatory responses in immunologic system.

Chlamydia trachomatis infection and anti-Hsp60 immunity: the two sides of the coin

Chlamydia trachomatis (CT) infection is one of the most common causes of reproductive tract diseases and infertility. CT-Hsp60 is synthesized during infection and is released in the bloodstream. As a consequence, immune cells will produce anti-CT-Hsp60 antibodies. Hsp60, a ubiquitous and evolutionarily conserved chaperonin, is normally sequestered inside the cell, particularly into mitochondria. However, upon cell stress, as well as during carcinogenesis, the chaperonin becomes exposed on the cell surface (sf-Hsp60) and/or is secreted from cells into the extracellular space and circulation. Reports in the literature on circulating Hsp and anti-Hsp antibodies are in many cases short on details about Hsp60 concentrations, and about the specificity spectra of the antibodies, their titers, and their true, direct, pathogenetic effects. Thus, more studies are still needed to obtain a definitive picture on these matters. Nevertheless, the information already available indicates that the concurrence of persistent CT infection and appearance of sf-Hsp60 can promote an autoimmune aggression towards stressed cells and the development of diseases such as autoimmune arthritis, multiple sclerosis, atherosclerosis, vasculitis, diabetes, and thyroiditis, among others. At the same time, immunocomplexes composed of anti-CT-Hsp60 antibodies and circulating Hsp60 (both CT and human) may form deposits in several anatomical locations, e.g., at the glomerular basal membrane. The opposite side of the coin is that pre-tumor and tumor cells with sf-Hsp60 can be destroyed with participation of the anti-Hsp60 antibody, thus stopping cancer progression before it is even noticed by the patient or physician.

A heat shock protein gene (Hsp70.1) is critically involved in the generation of the immune response to myelin antigen

Protracted inflammation has been associated with the generation of autoimmune responses. In this respect, increase in the chaperonin, heat shock protein 70 (hsp70) is an outcome of prolonged inflammatory stress. Previous experiments have shown that overexpression of inducible hsp70 in vitro enhanced myelin autoantigen recognition. To prove the role of hsp70 in myelin-directed responses in vivo, we applied a mouse deficient in the major gene encoding inducible hsp70, hsp70.1. Hsp70.1(-/-) mice sensitized for experimental autoimmune encephalomyelitis (EAE) with myelin oligodendrocyte glycoprotein (MOG) peptide 35-55, displayed almost complete resistance to the disease. This correlated with the loss of T cell proliferation and IFN-gamma production in response to MOG(35-55). T cell transfer experiments as well as antigen presentation assays in vitro demonstrated that hsp70 deficiency was associated with dysfunction in the activation of autoreactive T cells. Moreover, T cell responses to ovalbumin (OVA) peptide 323-339 were altered and CD4(+) T cells were more prone to TCR-induced apoptosis, suggesting broader spectrum of T cell defect in hsp70.1(-/-) mice. These results provide compelling evidence for generalized effect mediated by inducible hsp70 in the recognition of myelin self and non-self antigens that influences the cytokine profile of the immune response affecting autoimmune demyelination.

Stress proteins in CNS inflammation

Stress proteins or heat shock proteins (HSPs) are ubiquitous cellular components that have long been known to act as molecular chaperones. By assisting proper folding and transport of proteins, and by assisting in the degradation of aberrant proteins, they play key roles in cellular metabolism. The frequent accumulation of insoluble protein aggregates during chronic neurodegenerative disorders suggests failure of HSP functions to be a common denominator among such diseases. Recent developments have clarified that functions of HSPs extend well beyond their role in protein folding and degradation alone. Stress-inducible HSPs also regulate apoptosis, antigen presentation, inflammatory signalling pathways and, intriguingly, also serve as extracellular mediators of inflammation. Several receptors have been identified for extracellular HSPs, which control inflammatory pathways similar to those activated by cytokines and chemokines. In this review, both the traditional and the exciting novel functions of HSPs are discussed, with a focus on their relevance for neurodegeneration and neuroinflammation. Recent advances in this field suggest that HSPs represent attractive novel targets as well as therapeutic entities for CNS disorders.

Regulation of heat shock protein 70 release in astrocytes: role of signaling kinases

The ability to mount a successful stress response in the face of injury is critical to the long-term viability of individual cells and to the organism in general. The stress response, characterized in part by the upregulation of heat shock proteins, is compromised in several neurodegenerative disorders and in some neuronal populations, including motoneurons (MNs). Because astrocytes have a greater capacity than neurons to survive metabolic stress, and because they are intimately associated with the regulation of neuronal function, it is important to understand their stress response, so that we may to better appreciate the impact of stress on neuronal viability during injury or disease. We show that astrocytes subjected to hyperthermia upregulate Hsp/c70 in addition to intracellular signaling components including activated forms of extracellular-signal-regulated kinase (ERK1/2), Akt, and c-jun N-terminal kinase/stress activated protein kinase (JNK/SAPK). Furthermore, astrocytes release increasing amounts of Hsp/c70 into the extracellular environment following stress, an event that is abrogated when signaling through the ERK1/2 and phosphatidylinositol-3 kinase (PI3K) pathways is compromised and enhanced by inhibition of the JNK pathway. Last, we show that the Hsp/c70 is released from astrocytes in exosomes. Together, these data illustrate the diverse regulation of stress-induced Hsp/c70 release in exosomes, and the way in which the balance of activated signal transduction pathways affects this release. These data highlight how stressful insults can alter the microenvironment of an astrocyte, which may ultimately have implications for the survival of neighboring neurons.

The immunological basis for treatment of multiple sclerosis

During the last few years, the concept of multiple sclerosis (MS) as a pure inflammatory disease mediated by myelin reactive T cells has been challenged. Neither the specificity nor the mechanisms triggering or perpetuating the immune response are understood. Genetic studies have so far not identified therapeutic targets outside the HLA complex, but epidemiological and immunological studies have suggested putative pathogenetic factors which may be important in therapy or prevention, including the Epstein-Barr virus and vitamin D. Advances in the treatment of MS have been reached by manipulating the immune response where the pathogenesis of MS intersects experimental autoimmune encephalomyelitis, most recently by blocking T-cell migration through the blood-brain barrier. Antigen-specific approaches are effective in experimental models driven by a focused immune response against defined autoantigens, but MS may not fit into this concept. Novel candidate autoantigens which are not constitutively expressed in the brain, such as protein alpha-B crystallin or IgG V-region idiotopes, as well as evidence of pathogenetic heterogeneity and complexity, suggest that treating MS by tolerizing the immune system against an universal MS antigen may be a fata morgana. Further characterization of MS subtypes may lead to individualized treatment. However, shared immunological features, such as intrathecal production of oligoclonal IgG, suggest that potential therapeutic targets may be shared by most MS patients.

The Herpes simplex virus gene Pol expressed in herpes-associated erythema multiforme lesions upregulates/activates SP1 and inflammatory cytokines

BACKGROUND/AIMS

Herpes-simplex-virus-associated erythema multiforme (HAEM) is characterized by lesional skin expression of the viral protein Pol and localized inflammation. The objective of this study is to examine the mechanism whereby Pol induces localized inflammation.

METHODS

A431 cells transfected with Pol or an empty vector and lesional skin from HAEM or drug-induced erythema multiforme patients were examined for expression of the transcription factor SP1 and SP1-regulated genes by immunoblotting, immunohistochemistry and immunofluorescence.

RESULTS

SP1, TGF-beta, p21(waf1) and Hsp27 were upregulated in A431 cells transfected with Pol but not the empty vector. Expression was further increased by exposure to IFN-gamma. Pol+ HAEM lesional skin expressed SP1, Hsp27, TGF-beta and p21(waf1). Normal skin and drug-induced erythema multiforme lesional skin were negative.

CONCLUSION

The data indicate that Pol activates SP1, causing upregulation of SP1 target genes (notably TGF-beta) involved in localized inflammation. Upregulation is potentiated by IFN-gamma.

Differential inductions of small heat shock protein 27 and 1-Cys peroxiredoxin in reactive astrocytes in sulfatide-deficient mouse spinal cord

In myelinated fibers, various interactions among axons, oligodendrocytes, and astrocytes are present, particularly around the node of Ranvier. In the present study, we examined the protein composition of cerebroside sulfotransferase knockout (CST KO) mouse spinal cord by two-dimensional gel electrophoresis to examine the molecular changes resulting from the disruption of paranodal junctions in addition to the sulfatide-deficient condition. Interestingly, heat shock protein 27 (Hsp27) and 1-cys peroxiredoxin (1-Cys Prx) were both elevated in CST KO mice. Hsp27 was increased specifically in reactive astrocytes in the white matter, and the elevation was well correlated to the progression of neurologic symptoms. In contrast, 1-Cys Prx was elevated both in white and gray matter astrocytes in CST KO mice. These results suggest that astrocytes do not always respond stereotypically, as they display differences in their activation in these two regions. To determine whether these changes are specific to the sulfatide-deficient condition, spinal cords from CST KO mice and the hypomyelinating mutant shiverer mice were compared. The same distribution patterns of Hsp27 and 1-Cys Prx were found in reactive astrocytes in both CST KO and shiverer mice, suggesting that paranodal disruption with progressive nodal changes may underlie the similar reaction of white matter astrocytes. In contrast, CST KO and shiverer mice showed distinctly different localization patterns of connexin 43 and connexin 47, suggesting that intercellular communication between astrocytes and oligodendrocytes was different in these mutants. These results suggest that astrocytes may respond differentially to individual white matter abnormalities and may modulate specific axonal functions.

Interferon-gamma-induced expressions of heat shock protein 60 and heat shock protein 10 in C6 astroglioma cells: identification of the signal transducers and activators of transcription 3-binding site in bidirectional promoter

Heat shock protein 60 and heat shock protein 10 are mitochondrial chaperonin proteins. Here, we report that the expressions of heat shock protein 60 and heat shock protein 10 were upregulated in interferon-gamma-treated C6 astroglioma cells, and the 582 bp in the bidirectional promoter of the heat shock protein 60 and heat shock protein 10 genes is responsible for interferon-gamma-induced induction. The induction of heat shock protein 60 and heat shock protein 10 by interferon-gamma was virtually abolished by introducing mutations into the putative signal transducers and activators of transcription 3-response element in the promoter, and the same mutation impaired increment of the signal transducers and activators of transcription 3-binding after interferon-gamma treatment. Moreover, Rac1 GTPase was required for maximal heat shock protein 10 and heat shock protein 60 inductions by interferon-gamma. These results suggest that interferon-gamma-induced upregulations of heat shock protein 60 and heat shock protein 10 in C6 astroglioma cells are mediated by the signal transducers and activators of transcription 3-binding site, localized in the bidirectional promoter.

Hypoxia/reoxygenation and TGF-β increase αB-crystallin expression in human optic nerve head astrocytes

Reactive astrocytes in glaucomatous optic nerve changes are characterized by an increased expression of alphaB-crystallin and transforming growth factor-beta (TGF-beta). In the pathogenesis of glaucomatous optic nerve damage, ischemia/reperfusion injury may play an important role. The goal of the present study was to determine the influence of hypoxia/reoxygenation and TGF-beta on the expression of alphaB-crystallin in cultured human astrocytes of the optic nerve head (ONH). Cultured human astrocytes were incubated under hypoxic conditions (1% O2 for 4-12 h) with subsequent reoxygenation (12-24 h). Additionally, cells were treated with 1.0 ng/ml TGF-beta1 and TGF-beta2 for 12-48 h. Expression of alphaB-crystallin was examined by Northern- and Western-blotting. Levels of TGF-beta1 and TGF-beta2 were analyzed by RT-PCR analysis and ELISA. The effect of TGF-beta blocking on the hypoxia/reoxygenation modulated expression of alphaB-crystallin was investigated by simultaneous incubation with neutralizing antibodies against TGF-beta during the reoxygenation phase. Hypoxia/reoxygenation increased the expression of alphaB-crystallin at the mRNA (2.8- to 3.1-fold) and protein level (1.8- to 2.1-fold). Treatment with 1.0 ng/ml TGF-beta1 and TGF-beta2 for 12-48 h markedly enhanced alphaB-crystallin mRNA expression approximately three- to fourfold. Using Western blot analysis, this increase ranged from 2 to 3 times. Both cytokines showed a twofold increase after 12 and 24 h of reoxygenation at the mRNA and a two- to threefold increase at the protein level. Simultaneous treatment with neutralizing antibodies against both TGF-beta isoforms prevented the hypoxia/reoxygenation-mediated elevation of alphaB-crystallin. The process of hypoxia/reoxygenation is capable of inducing the expression of alphaB-crystallin and TGF-ss in cultured ONH astrocytes. Therefore, optimization of conditions leading to hypoxia/reoxygenation in the ONH of glaucomatous patients may help to lower the incidence of characteristic changes in the optic nerve.

Basal and infection-induced levels of heat shock proteins in human aging

Heat shock proteins (Hsp) are ubiquitously expressed proteins, which are highly inducible by a variety of stressful stimuli. As organisms age, various denatured proteins such as proteins modified by oxidation have been detected. Such abnormal proteins might serve as stress signals for the induction of Hsp, which plays indispensable roles in protecting proteins from denaturation. Although it is well known that the heat shock induced expression of Hsp decreases with age, little attention has been given to the unstimulated, basal levels of Hsp. Therefore, a study was performed to examine the expression pattern of various Hsp with aging, under normal physiological conditions in human peripheral blood cells. The basal levels of Hsp32, Hsp70 and Hsp90 increased significantly with age in controls but not patients. Moreover, the levels of Hsp32, Hsp70, Hsp90, but not Hsp27 correlated positively among each other, indicating both common and different regulatory mechanisms. Higher levels of Hsp32, Hsp70 and Hsp90 were noticed in patients with inflammation, a commonly occurring natural stimulant of Hsp production, compared to control subjects. The production of Hsp appeared to be related to the circulating levels of C-reactive protein and cytokines.

CRYAB promoter polymorphisms: Influence on multiple sclerosis susceptibility and clinical presentation

BACKGROUND

alphaB-crystallin is a molecular chaperone and potential myelin antigen, up-regulated in the earlier stages of multiple sclerosis (MS) lesions. In the alphaB-crystallin gene (CRYAB), single nucleotide polymorphisms (SNPs) have been associated with MS susceptibility (g.CRYAB-652A>G) and a rapidly progressive clinical course (g.CRYAB-650C>G).

METHOD

CRYAB was screened for mutations in 233 MS patients and 96 controls. Genomic DNA was extracted and the coding and 3' and 5' untranslated regions were amplified by PCR. Subsequently, the products were analysed by Single Strand Conformation Polymorphism technique followed by DNA sequencing of aberrant conformers.

RESULTS

In CRYAB (Genbank ) no mutations were found but SNPs were identified in the promoter region (g.CRYAB-249C>G, g.CRYAB-650C>G and g.CRYAB-652A>G), and intronic region (g.CRYAB.2398T>G). The g.CRYAB-249C>G genotype distribution was significantly different between groups (chi(2), p=0.01), caused by differences between Relapsing Remitting MS (RRMS) and controls (chi(2), p=0.025) and Secondary Progressive MS (SPMS) and controls (chi(2), p=0.05). In addition, a significant difference was observed in the g.CRYAB-249C>G allele distribution (chi(2), p=0.04), caused by a difference between SPMS and controls (chi(2), p=0.01). In RRMS and SPMS a tendency of the g.CRYAB-249GG genotype being associated with an earlier age of onset (p=0.05) and a slowly progressive cause (p=0.07) was found. Multiple sequence alignment showed conservation of the g.CRYAB-249*C between mammalian CRAYB genes and within the small heat shock protein gene family.

CONCLUSION

CRYAB polymorphisms may be involved in the pathogenesis of MS by mechanisms that could involve increased expression of the superantigen alphaB-crystallin and modulation of the immune response. CRYAB polymorphisms should be included in future multivariate biomaker studies in MS.

NO-induced downregulation of HSP10 and HSP60 expression in the postischemic brain

Heat shock protein 60 (HSP60) and HSP10 are mitochondrial chaperonin proteins and are responsible for the folding of newly imported proteins and 13 polypeptides encoded by mitochondrial DNA. The expressions of HSP60 and HSP10 are regulated simultaneously because these genes are localized head to head on chromosome, separated by a bidirectional promoter, which harbors heat shock element (HSE), CHOP, STAT3, and SP1 binding sites. In the present study, we show that the expressions of HSP60 and HSP10 in the brain after middle cerebral artery occlusion (MCAO) are induced significantly. Interestingly, the expressions of HSP60 and HSP10 were further upregulated by the administration of aminoguanidine (AG), an inhibitor of the inducible nitric oxide synthase (iNOS), which is known to reduce ischemic damage in an animal model after MCAO. The results obtained in the present study suggest that HSP10 and HSP60 are induced in the postischemic brain, yet are downregulated by NO generated from 12 hr after MCAO/reperfusion. The downregulation of HSP60 and HSP10 by NO were confirmed in vitro, wherein HSP10 and SHP60 expressions were increased by treatment of LPS and IFN gamma (LPS/INF gamma) in C6 astroglioma cells and further upregulated by NMMA, another iNOS inhibitor. Reporter gene analysis combined with deletion and mutation studies showed that STAT3 binding site in the bidirectional promoter is responsible for LPS/INF gamma-induced upregulation and for downregulation by NO. Our results indicated that NO suppresses HSP60 and HSP10 inductions in the postischemic brain by suppressing STAT3 binding to its recognition site.

Retinal glial cell responses and Fas/FasL activation in rats with chronic ocular hypertension

Responses in the retina post injury provoke glial reactions that are not completely understood. This study investigated the reaction of retinal glial cells and the expression and localization of the Fas and Fas-ligand (FasL) in rats with chronic ocular hypertension. Experimental glaucoma was induced in one eye of 60 Sprague-Dawley rats by cauterizing three episcleral vessels. It caused a moderate intraocular pressure (IOP) elevation and significant retinal ganglion cell (RGC) loss for at least 6 weeks in all animals. Immunohistochemical analysis revealed that the expression of GFAP and OX-42 increased in the injured retinae. Fas/FasL immunoreactivity was elevated in the microglia, and we also observed an incremental increase in Fas associated death domain (FADD) immunoreactivity in Müller glial cells and RGCs in the IOP-elevated retinae. The activation of glial cells and upregulation of Fas and FasL suggest that glial cells may contribute to Fas-mediated cell death in the neurodegeneration process of chronic ocular hypertensive retinal insult.

Proteomic analysis of the effects of cocaine on the enhancement of HIV-1 replication in normal human astrocytes (NHA)

The US is experiencing an epidemic of cocaine use entangled with HIV-1 infection. Normal human astrocytes (NHA) are susceptible to HIV-1 infection. We utilized LTR-R/U5 amplification, p24 antigen assay and the proteomic method of difference gel electrophoresis (DIGE) combined with protein identification through HPLC-MS/MS to investigate the effect of cocaine on HIV-1 infectivity and the proteomic profile of NHA, respectively. Data demonstrate that cocaine significantly upregulates HIV-1 infection in NHA as measured by LTR-R/U5 amplification and p24 antigen assay. Further, our results show for the first time that cocaine differentially regulates the expression of a number of proteins by NHA that may play a role in the neuropathogenesis of HIV-1 disease.

AlphaB-crystallin-reactive T cells from knockout mice are not encephalitogenic

Alpha B-crystallin (alphaB) is a small heat shock protein that is strongly up-regulated in multiple sclerosis (MS) brain tissue, and can induce strong T cell responses. Assessing a potential encephalitogenic function for alphaB protein in MS and experimental autoimmune encephalomyelitis (EAE) has been challenging due to its ubiquitous expression that likely maintains central and peripheral tolerance to this protein in mice. To address this issue, we obtained alphaB-knockout (alphaB-KO) mice in H-2b background that lack immune tolerance to alphaB protein, and thus are capable of developing alphaB-specific T cells that could be tested for encephalitogenic activity after transfer into alphaB-expressing wild type (WT) mice. We found that T cell lines from spleens of alphaB protein-immunized alphaB-KO mice proliferated strongly to alphaB protein itself, and the majority of T cells were CD4+ and capable of secreting pro-inflammatory Th1 cytokines upon restimulation. However, transfer of such alphaB-reactive T cells back into WT recipients was not sufficient to induce EAE, compared to the transfer of mouse MOG-35-55 peptide-reactive T cells from the same donors that induced severe EAE in recipients. Moreover, alphaB-specific T cells failed to augment severity of actively induced EAE in WT mice that were expressing high levels of alphaB message in the CNS at the time of transfer. These results suggest that alphaB-specific T cells are immunocompetent but not encephalitogenic in 129SvEv mice, and that immune tolerance may not be the main factor that limits the encephalitogenic potential of alphaB.

Mechanisms of interleukin-6 protection against ischemia-reperfusion injury in rat liver

Numerous animal studies simulating liver injury have demonstrated that interleukin-6 (IL-6) exerts a protective effect. This study was designed to further analyze the molecular mechanisms underlying the protective role of IL-6 in a rat model of liver ischemia/reperfusion injury. We show that IL-6: (i) at high doses reduces cell damage which occurs in ischemic-reperfused liver, while at low doses displays only a limited protective capacity, (ii) anticipates and enhances hepatocyte compensatory proliferation seen in ischemic-reperfused liver also at a low, more pharmacologically acceptable dose, (iii) sustains the acute phase response which is dampened in ischemic-reperfused liver, (iv) strengthens the heat shock-stress response shown by ischemic-reperfused liver and (v) overcomes the dysfunctions of the unfolding protein response found in ischemic-reperfused liver. We also show that IL-6-enhanced STAT3 activation probably plays a crucial role in the potentiation of the different protective pathways activated in ischemic-reperfused liver. Our data confirm that IL-6 is a potential therapeutic in liver injury of different etiologies and reveal novel mechanisms by which IL-6 sustains liver function after ischemia/reperfusion injury.

Elucidation of ATP-stimulated stress protein expression of RBA-2 type-2 astrocytes: ATP potentiate HSP60 and Cu/Zn SOD expression and stimulates pI shift of peroxiredoxin II

ATP has been shown to mediate stress responses in the brain. The present study examined the ATP-stimulated stress protein expression of RBA-2 type-2 astrocytes. Our results revealed that ATP stimulated HSP60 expression in a dose- and time-dependent manner. The stimulation requires a minimal ATP concentration of 500 microM and high concentration of extracellular ATP (1 mM) stimulated a significant increase of HSP60 expression from 2 to 24 h. In addition, the ATP-stimulated HSP60 expressions were inhibited by inhibitors for protein kinase C (PKC) and phospholipase D (PLD), and by antioxidants, resveratrol, and catalase. Furthermore, ATP stimulated the expression of Cu/Zn superoxide dismutase (SOD). In addition, ATP and P2X7 receptor selective agonist BzATP also decreased mitochondria membrane potential measured by flow cytometry. To further examine the proteins involving in ATP-mediated stress responses, we conducted proteomic analysis. We found that RBA-2 astrocytes possess abundant peroxiredoxin II (Prx II), an antioxidant enzyme. ATP and exogenous H2O2 stimulated Prx II shifting from oxidized form to reduced form. Thus, we concluded that ATP potentiated the expression of HSP60 and Cu/Zn SOD, and decreased mitochondria membrane potential. In addition, RBA-2 astrocytes expressed Prx II that might also serve as a protective mechanism to control the concentration of reactive oxygen species.

Brain-derived heat shock protein 70-peptide complexes induce NK cell-dependent tolerance to experimental autoimmune encephalomyelitis

Heat shock proteins (Hsp) are markedly up-regulated at sites of inflammation during autoimmune diseases like experimental autoimmune encephalomyelitis (EAE). In this study, we show that Hsp70-peptide complexes (pc) isolated from brains of mice with EAE prevented the development of EAE clinically and pathologically when administered before proteolipid protein 139-151 (PLP139-151) immunization. In contrast, pure Hsp70 or Hsp70-pc derived from brains of healthy mice or other inflamed tissue did not modulate the expression of EAE. In animals in which EAE had been suppressed by Hsp70-pc, lymphocytes showed increased cell death in response to PLP139-151 that correlated with elevated IFN-gamma and NO production. Coculture of spleen cells from Hsp70-pc immunized mice with spleen cells from untreated EAE mice, in addition to depletion experiments, showed that NK cells reduced reactivity to PLP139-151. Transfer of NK cells from Hsp70-pc-immunized mice to recipients sensitized for EAE abolished disease development. Thus, we propose that Hsp70 demonstrate the ability to bind to peptides generated during brain inflammation and to induce a regulatory NK cell population that is capable of preventing subsequent autoimmunization for EAE.