Association between plasma levels of heat shock protein 60 and cardiovascular disease in patients with diabetes mellitus

Reactivity to neural tissue epitopes, aquaporin 4 and heat shock protein 60 is associated with activated immune-inflammatory pathways and the onset of delirium following hip fracture surgery

OBJECTIVES

Activation of the immune-inflammatory response system (IRS) and a deficiency in the compensatory immunoregulatory system (CIRS), neuronal injuries, and alterations in the glutamate receptor (GlutaR), aquaporin-4 (AQP4) and heat shock protein 60 (HSP60) are involved in delirium. Increased serum levels of neurofilament protein (NFP), glial fibrillary acidic protein (GFAP) and myelin basic protein (MBP) are biomarkers of neuronal injury. This investigation delineates whether elevated IgA/IgG reactivity against those self-antigens is associated with delirium severity and IRS activation.

METHODS

We measured peak Delirium Rating Scale (DRS) scores on days 2 and 3 following surgery in 59 hip fractured older adults, and IgA and IgG antibody levels against MBP, NFP, GFAP and myelin oligodendrocyte glycoprotein (MOG), metabotropic glutamate receptors mGluRs 1 and 5, N-Methyl-D-Aspartate receptor (NMDAR) GLU₁ (NR₁) and GLU₂ (NR₂), APQ4 and HSP60.

RESULTS

The IgA antibody levels against those self-antigens, especially GFAP, MBP and HSP60, strongly predict peak DRS scores on days 2 and 3 post-surgery. IgA reactivity against NMDAR and baseline DRS scores explained 40.6% of the variance in peak DRS scores, while IgA against NMDAR, IgG against MBP and age explained 29.1% of the variance in the IRS/CIRS ratio. There was no correlation between DRS scores and IgG directed against other self-antigens.

CONCLUSIONS

Increased IgA levels against neuronal self-antigens, AQP4 and HSP60 are risk factors for delirium. Polyreactive antibody-associated breakdown of immune tolerance, IRS activation and injuries in the neuronal cytoskeleton, oligodendrocytes, astrocytes, glial cells, and myelin sheath are involved in the pathophysiology of delirium.

Extracellular Hsp90α, which participates in vascular inflammation, is a novel serum predictor of atherosclerosis in type 2 diabetes

INTRODUCTION

Atherosclerosis is the main pathological change in diabetic angiopathy, and vascular inflammation plays an important role in early atherosclerosis. Extracellular heat shock protein 90 (eHsp90) is secreted into the serum and is involved in various physiological and pathophysiological processes. However, the specific mechanism of eHsp90 in early atherosclerosis remains unclear. This study explored the relationship between Hsp90 and diabetic lower extremity arterial disease and investigated the expression of eHsp90 in vascular endothelial cells under environmental stimulation and the function and mechanism of eHsp90α involved in diabetic atherosclerosis.

RESEARCH DESIGN AND METHODS

One hundred and three selected patients were divided into three groups: the diabetes mellitus group (n=27), the diabetic lower extremity arterial disease group (n=46), and the diabetic critical limb ischemia group (n=30). The relationships among serum Hsp90, oxidative stress indexes, and patient outcomes and the correlations among the indexes were analyzed. H&E staining and immunohistochemistry were used to observe the vasculature of amputated feet from patients with diabetic foot. An oxidative stress endothelial injury model was established under high glucose in vitro to explore the role of eHsp90 release in atherosclerosis progression.

RESULTS

The level of serum Hsp90 was upregulated with aggravation of diabetic vascular disease. Hsp90α was correlated with malondialdehyde to some extent and was an independent risk factor in the progression of diabetic vascular disease, with predictive ability. The expression area of Hsp90α was consistent with the area of inflammatory infiltration in the vessel lumen. Vascular endothelial cells were found to increase eHsp90α secretion under stress. Then inhibition of eHsp90α can reduce the degree of cellular inflammation and damage. Endothelial cell-conditioned medium and recombinant human Hsp90α increased monocyte migration via the low-denisity lipoprotein receptor-related protein 1 (LRP1) receptor to promote disease progression.

CONCLUSIONS

eHsp90α plays a critical role in the early inflammatory injury stage of atherosclerosis.

TRIAL REGISTRATION NUMBER

NCT04787770.

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.

Plasma heat shock protein response to euglycemia in type 2 diabetes

INTRODUCTION

Glucose variability is associated with mortality and macrovascular diabetes complications. The mechanisms through which glucose variability mediates tissue damage are not well understood, although cellular oxidative stress is likely involved. As heat shock proteins (HSPs) play a role in the pathogenesis of type 2 diabetes (T2D) complications and are rapidly responsive, we hypothesized that HSP-related proteins (HSPRPs) would differ in diabetes and may respond to glucose normalization.

RESEARCH DESIGN AND METHODS

A prospective, parallel study in T2D (n=23) and controls (n=23) was undertaken. T2D subjects underwent insulin-induced blood glucose normalization from baseline 7.6±0.4 mmol/L (136.8±7.2 mg/dL) to 4.5±0.07 mmol/L (81±1.2 mg/dL) for 1 hour. Control subjects were maintained at 4.9±0.1 mmol/L (88.2±1.8 mg/dL). Slow Off-rate Modified Aptamer-scan plasma protein measurement determined a panel of HSPRPs.

RESULTS

At baseline, E3-ubiquitin-protein ligase (carboxyl-terminus of Hsc70 interacting protein (CHIP) or HSPABP2) was lower (p=0.03) and ubiquitin-conjugating enzyme E2G2 higher (p=0.003) in T2D versus controls. Following glucose normalization, DnaJ homolog subfamily B member 1 (DNAJB1 or HSP40) was reduced (p=0.02) in T2D, with HSP beta-1 (HSPB1) and HSP-70-1A (HSP70-1A) (p=0.07 and p=0.09, respectively) also approaching significance relative to T2D baseline levels.

CONCLUSIONS

Key HSPRPs involved in critical protein interactions, CHIP and UBE2G2, were altered in diabetes at baseline. DNAJB1 fell in response to euglycemia, suggesting that HSPs are reacting to basal stress that could be mitigated by tight glucose control with reduction of glucose variability.

Are Heat Shock Proteins an Important Link between Type 2 Diabetes and Alzheimer Disease?

Type 2 diabetes (T2D) and Alzheimer’s disease (AD) are growing in prevalence worldwide. The development of T2D increases the risk of AD disease, while AD patients can show glucose imbalance due to an increased insulin resistance. T2D and AD share similar pathological features and underlying mechanisms, including the deposition of amyloidogenic peptides in pancreatic islets (i.e., islet amyloid polypeptide; IAPP) and brain (β-Amyloid; Aβ). Both IAPP and Aβ can undergo misfolding and aggregation and accumulate in the extracellular space of their respective tissues of origin. As a main response to protein misfolding, there is evidence of the role of heat shock proteins (HSPs) in moderating T2D and AD. HSPs play a pivotal role in cell homeostasis by providing cytoprotection during acute and chronic metabolic stresses. In T2D and AD, intracellular HSP (iHSP) levels are reduced, potentially due to the ability of the cell to export HSPs to the extracellular space (eHSP). The increase in eHSPs can contribute to oxidative damage and is associated with various pro-inflammatory pathways in T2D and AD. Here, we review the role of HSP in moderating T2D and AD, as well as propose that these chaperone proteins are an important link in the relationship between T2D and AD.

Heat Shock Protein 60 in Cardiovascular Physiology and Diseases

Heat shock protein 60 (HSP60) is a highly conserved protein abundantly expressed in both prokaryotic and eukaryotic cells. In mammals, HSP60 has been primarily considered to reside in the mitochondria, where HSP60 and HSP10 form a complex and facilitate mitochondrial protein folding. However, HSP60 is also observed in the cytoplasm, the plasma membrane, and the extracellular space. HSP60 regulates a broad spectrum of cellular events including protein trafficking, peptide hormone signaling, cell survival, cell proliferation, inflammation, and immunization. In the cardiovascular system, growing evidence indicates that HSP60 could not only play an important role under physiological conditions, but also regulate the initiation and progression of heart failure and atherosclerosis. In this review, we focus on recent progress in understanding the function of HSP60 in cardiomyocytes, endothelial cells, and vascular smooth muscle cells (VSMCs), respectively, and discuss the related signaling pathways that have been found in these cells, so as to illustrate the role of HSP60 in the development of cardiovascular disease.

High risk for cardiovascular disease in postmenopausal breast cancer survivors

OBJECTIVE

Breast cancer patients have a higher mortality risk of cardiovascular disease (CVD) than women from the general population. CVD risk may increase significantly in postmenopausal women with early-stage breast cancer. The aim of this study was to evaluate risk factors for CVD in postmenopausal breast cancer survivors.

METHODS

In this cross-sectional study, 96 postmenopausal breast cancer survivors were compared with 192 postmenopausal women. The main group included women with amenorrhea >12 months, aged ≥45 years, with breast cancer, and without established CVD. The control group fulfilled the same criteria, but did not have breast cancer. Groups were matched by age, time since menopause, and body mass index, in a ratio of 1 case to 2 controls (1:2). Women with three or more of the following criteria were diagnosed with metabolic syndrome: waist circumference >88 cm; triglycerides ≥150 mg/dL; high-density lipoprotein cholesterol <50 mg/dL; blood pressure ≥130/85 mm Hg; and glucose ≥100 mg/dL. Immunoassays were used (enzyme-linked immunosorbent assay test) for measurement of plasma heat shock proteins (HSP) 60 and 70 concentrations. Atherosclerotic disease was determined by intima-media thickness (>1 mm) of the carotid arteries and/or the presence of atheromatous plaque assessed by carotid artery ultrasound (scanner duplex).

RESULTS

Breast cancer patients had higher HSP60 levels and lower HSP70 levels than controls (P < 0.05). Analysis showed that the odds of developing metabolic syndrome (odds ratio [OR] = 4.21, 95% CI, 2.28-7.76), atheromatous plaque (OR = 2.61, 95% CI, 1.19-5.72), diabetes (OR = 4.42; 95% CI, 1.86-10.49), hypertriglyceridemia (OR = 2.32, 95% CI, 1.33-4.0), and increased waist circumference (OR = 11.22, 95% CI, 4.0-31.65) was significantly higher in women treated for cancer than in women without breast cancer.

CONCLUSIONS

Postmenopausal breast cancer survivors had a stronger association with risk factors for cardiovascular disease than postmenopausal women without breast cancer.

Association between circulating levels of heat-shock protein 27 and aggressive periodontitis

Heat-shock protein (Hsp) 27 is a major intracellular molecular chaperone and controller of intracellular responses to inflammatory signals. In the extracellular space, recombinant Hsp27 has been described to exert anti-inflammatory activities. The aim of this study was to assess the association between circulating levels of Hsp27 and different types of periodontitis. Pro- and anti-inflammatory cytokines and the stress proteins Hsp27 and Hsp60 with proposed anti- and pro-inflammatory properties, respectively, were measured by two-site ELISA in the serum of patients with aggressive periodontitis (AgP, n = 30), chronic periodontitis (CP, n = 29) and periodontally healthy controls (H, n = 28). Furthermore, Hsp27 and Hsp60 levels were also measured longitudinally in 12 AgP patients at 6 time points up to 3 months after treatment. AgP patients had lower levels of Hsp27 compared to CP patients and healthy subjects (adjusted one-way ANOVA, p < 0.001, followed by post hoc Tukey HSD comparisons), while no differences in levels of Hsp60 or cytokines between the three groups were detected. In CP patients and H subjects, the systemic Hsp27 levels correlated with Hsp60 (r = 0.43, p < 0.001; r = 0.59, p < 0.001, respectively) and with pro-inflammatory cytokines TNF-α (r = 0.48, p < 0.001; r = 0.55, p < 0.001, respectively) and IL-6 (r = 0.44, p < 0.01). However, no such correlations were detected in AgP cases. No consistent temporal patterns of changes of Hsp27 concentration were detected across AgP patients following periodontal treatment. This study provides the first evidence that Hsp27 may be differentially expressed and regulated in AgP patients as compared with CP patients and healthy individuals.

Extracellular cell stress (heat shock) proteins-immune responses and disease: an overview

Extracellular cell stress proteins are highly conserved phylogenetically and have been shown to act as powerful signalling agonists and receptors for selected ligands in several different settings. They also act as immunostimulatory 'danger signals' for the innate and adaptive immune systems. Other studies have shown that cell stress proteins and the induction of immune reactivity to self-cell stress proteins can attenuate disease processes. Some proteins (e.g. Hsp60, Hsp70, gp96) exhibit both inflammatory and anti-inflammatory properties, depending on the context in which they encounter responding immune cells. The burgeoning literature reporting the presence of stress proteins in a range of biological fluids in healthy individuals/non-diseased settings, the association of extracellular stress protein levels with a plethora of clinical and pathological conditions and the selective expression of a membrane form of Hsp70 on cancer cells now supports the concept that extracellular cell stress proteins are involved in maintaining/regulating organismal homeostasis and in disease processes and phenotype. Cell stress proteins, therefore, form a biologically complex extracellular cell stress protein network having diverse biological, homeostatic and immunomodulatory properties, the understanding of which offers exciting opportunities for delivering novel approaches to predict, identify, diagnose, manage and treat disease.This article is part of the theme issue 'Heat shock proteins as modulators and therapeutic targets of chronic disease: an integrated perspective'.

Heat Shock Proteins in Vascular Diabetic Complications: Review and Future Perspective

Heat shock proteins (HSPs) are a large family of proteins highly conserved throughout evolution because of their unique cytoprotective properties. Besides assisting protein refolding and regulating proteostasis under stressful conditions, HSPs also play an important role in protecting cells from oxidative stress, inflammation, and apoptosis. Therefore, HSPs are crucial in counteracting the deleterious effects of hyperglycemia in target organs of diabetes vascular complications. Changes in HSP expression have been demonstrated in diabetic complications and functionally related to hyperglycemia-induced cell injury. Moreover, associations between diabetic complications and altered circulating levels of both HSPs and anti-HSPs have been shown in clinical studies. HSPs thus represent an exciting therapeutic opportunity and might also be valuable as clinical biomarkers. However, this field of research is still in its infancy and further studies in both experimental diabetes and humans are required to gain a full understanding of HSP relevance. In this review, we summarize current knowledge and discuss future perspective.

Paying for the Tolls: The High Cost of the Innate Immune System for the Cardiac Myocyte

The cardiac myocyte differs strikingly from the specialized cells of the immune system, which has two different responses to invading organisms and tissue damage. Adaptive or acquired immunity generates highly specific antibodies in response to threats and is an essential component of immunity; however, adaptive immunity can take 4-7 days to mobilize, and a more primitive response, innate immunity, fills the gap. Innate immunity is expressed in complex and in primitive life forms. Specialized receptors, Toll-like receptors (TLRs), which are widely distributed throughout different tissues recognize danger signals and rapidly respond with the release of noxious substances, such as TNFα. The problem is that many endogenous molecules have been found to act as ligands for specific TLRs, and when these molecules are released into the extracellular environment, they can cause problems by activating innate immunity and an inflammatory response. In cardiac myocytes heat shock protein (HSP)60 can activate TLR4, as can HMGB1, and this type of response can amplify the response to ischemia/reperfusion leading to increased cell and tissue injury. Activation of TLRs can potentially amplify chronic, inflammatory diseases, such as ischemic heart failure. Thus, it is important to understand the regulation of the TLRs and their downstream effects. This chapter will focus on the TLRs and cardiac myocytes.

Biomarkers of Diabetic Retinopathy

Diabetic retinopathy (DR), a leading cause of acquired vision loss, is a microvascular complication of diabetes. While traditional risk factors for diabetic retinopathy including longer duration of diabetes, poor blood glucose control, and dyslipidemia are helpful in stratifying patient's risk for developing retinopathy, many patients without these traditional risk factors develop DR; furthermore, there are persons with long diabetes duration who do not develop DR. Thus, identifying biomarkers to predict DR or to determine therapeutic response is important. A biomarker can be defined as a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. Incorporation of biomarkers into risk stratification of persons with diabetes would likely aid in early diagnosis and guide treatment methods for those with DR or with worsening DR. Systemic biomarkers of DR include serum measures including genomic, proteomic, and metabolomics biomarkers. Ocular biomarkers including tears and vitreous and retinal vascular structural changes have also been studied extensively to prognosticate the risk of DR development. The current studies on biomarkers are limited by the need for larger sample sizes, cross-validation in different populations and ethnic groups, and time-efficient and cost-effective analytical techniques. Future research is important to explore novel DR biomarkers that are non-invasive, rapid, economical, and accurate to help reduce the incidence and progression of DR in people with diabetes.

Heat Shock Proteins and Diabetes

Diabetes is a chronic disease, and its prevalence continues to rise and can increase the risk for the progression of microvascular (such as nephropathy, retinopathy and neuropathy) and also macrovascular complications. Diabetes is a condition in which the oxidative stress and inflammation rise. Heat shock proteins (HSPs) are a highly conserved family of proteins that are expressed by all cells exposed to environmental stress, and they have diverse functions. In patients with diabetes, the expression and levels of HSPs decrease, but these chaperones can aid in improving some complications of diabetes, such as oxidative stress and inflammation. (The suppression of some HSPs is associated with a generalized increase in tissue inflammation.) In this review, we summarize the current understanding of HSPs in diabetes as well as their complications, and we also highlight their potential role as therapeutic targets in diabetes.

Diastolic dysfunction in prediabetic male rats: Role of mitochondrial oxidative stress

Although incidence and prevalence of prediabetes are increasing, little is known about its cardiac effects. Therefore, our aim was to investigate the effect of prediabetes on cardiac function and to characterize parameters and pathways associated with deteriorated cardiac performance. Long-Evans rats were fed with either control or high-fat chow for 21 wk and treated with a single low dose (20 mg/kg) of streptozotocin at week 4 High-fat and streptozotocin treatment induced prediabetes as characterized by slightly elevated fasting blood glucose, impaired glucose and insulin tolerance, increased visceral adipose tissue and plasma leptin levels, as well as sensory neuropathy. In prediabetic animals, a mild diastolic dysfunction was observed, the number of myocardial lipid droplets increased, and left ventricular mass and wall thickness were elevated; however, no molecular sign of fibrosis or cardiac hypertrophy was shown. In prediabetes, production of reactive oxygen species was elevated in subsarcolemmal mitochondria. Expression of mitofusin-2 was increased, while the phosphorylation of phospholamban and expression of Bcl-2/adenovirus E1B 19-kDa protein-interacting protein 3 (BNIP3, a marker of mitophagy) decreased. However, expression of other markers of cardiac auto- and mitophagy, mitochondrial dynamics, inflammation, heat shock proteins, Ca²⁺/calmodulin-dependent protein kinase II, mammalian target of rapamycin, or apoptotic pathways were unchanged in prediabetes. This is the first comprehensive analysis of cardiac effects of prediabetes indicating that mild diastolic dysfunction and cardiac hypertrophy are multifactorial phenomena that are associated with early changes in mitophagy, cardiac lipid accumulation, and elevated oxidative stress and that prediabetes-induced oxidative stress originates from the subsarcolemmal mitochondria.

Plasma Heat Shock Proteins (HSPs) 70 and 47 levels in diabetic foot and its possible correlation with clinical variables in a North Indian Tertiary care hospital

OBJECTIVE

HSPs have been proposed to have a role in the wound healing process, supported by finding that its expression is rapidly induced after skin is wounded in animal models. Because of this phenomenon, we have made a hypothesis that circulating HSPs will have any relationship with DFU.

METHODS

The circulating levels of HSP 70 and HSP 47 were measured in diabetic patients with an ulcer (Group A: n=30), without ulcer (Group B: n=30) and healthy subjects (Group C: n=30).

RESULTS

Diabetic foot ulcer showed higher median plasma level of HSP 70 [3229.01 (1984.5-4137.1) vs 1625.7 (1435.1-2253.5) vs 1025.7 (835.1-1653.5)] ng/ml and HSP 47 [2.33 (2.118-2.58) vs 0.98 (0.83-1.07) vs 0.58 (0.42-0.68) pg/ml] of the diabetic foot, diabetic control and healthy subjects. Odds ratio and risk ratio for DFU after age adjusted were BMI (>25 kg/m(2)) [OR 1.78, RR 1.35], HbA1c>7% [OR 3.37), RR 1.76], neuropathy [OR 5.79, RR 3.13], retinopathy [OR 3.44, RR 1.82], hypertension [OR 1.54, RR 1.18], and smoking cessation [OR 4.53, RR 2.09].

CONCLUSION

In the near future, it would be interesting to find out whether this high plasma HSPs precedes in early would healing mechanism and will have a relationship with type of infections and/or nature of therapy for infection in such patients.

Extracellular cell stress proteins as biomarkers of human disease

Although heat-shock (cell stress) proteins are commonly considered as being intracellular molecular chaperones that undertake a number of cytoprotective and cellular housekeeping functions, there is now a wealth of evidence to indicate that these proteins can be released by cells via active processes. Many molecular chaperones are secreted, or exist as cell surface proteins which can act as powerful signalling agonists and also as receptors for selected ligands. Levels of heat-shock (cell stress) proteins in biological fluids are now being associated with a plethora of clinical conditions, and these proteins therefore have potential utility as biomarkers of disease and/or response to therapeutic intervention. The present article summarizes current knowledge relating to extracellular cell stress proteins as biomarkers of human disease.

Biomarkers of Coronary Artery Disease Differ Between Asians and Caucasians in the General Population

Coronary artery disease (CAD) markers have not been thoroughly investigated among Asians. The incidence of CAD, however, is rising rapidly in Asia. In this review, we systematically discuss publications that compare CAD biomarkers between Asians and Caucasians in the general population. A PubMed search yielded 5,570 hits, containing 59 articles describing 47 unique cohorts that directly compare Asians with Caucasians. Ten biomarkers were taken into account for this review: total cholesterol; triglycerides; high-density lipoprotein cholesterol; low-density lipoprotein cholesterol; C-reactive protein; glucose; insulin; glycated hemoglobin; fibrinogen; and plasminogen activator inhibitor-1. Triglycerides were 1.13-fold higher in South Asians than in Caucasians, and insulin levels were 1.33-fold higher. In Japanese and Chinese subjects, lower C-reactive protein levels were reported: 0.52 and 0.36-fold, respectively. Ethnicity-specific prognostic measures of CAD biomarkers were rarely reported. CAD biomarker levels differ between Asians and Caucasians and among Asian ethnic groups in population-based cohorts. The ethnicity-specific prognostic value of CAD biomarkers is yet to be determined.

Cardiac myocyte exosomes: stability, HSP60, and proteomics

Exosomes, which are 50- to 100-nm-diameter lipid vesicles, have been implicated in intercellular communication, including transmitting malignancy, and as a way for viral particles to evade detection while spreading to new cells. Previously, we demonstrated that adult cardiac myocytes release heat shock protein (HSP)60 in exosomes. Extracellular HSP60, when not in exosomes, causes cardiac myocyte apoptosis via the activation of Toll-like receptor 4. Thus, release of HSP60 from exosomes would be damaging to the surrounding cardiac myocytes. We hypothesized that 1) pathological changes in the environment, such as fever, change in pH, or ethanol consumption, would increase exosome permeability; 2) different exosome inducers would result in different exosomal protein content; 3) ethanol at "physiological" concentrations would cause exosome release; and 4) ROS production is an underlying mechanism of increased exosome production. We found the following: first, exosomes retained their protein cargo under different physiological/pathological conditions, based on Western blot analyses. Second, mass spectrometry demonstrated that the protein content of cardiac exosomes differed significantly from other types of exosomes in the literature and contained cytosolic, sarcomeric, and mitochondrial proteins. Third, ethanol did not affect exosome stability but greatly increased the production of exosomes by cardiac myocytes. Fourth, ethanol- and hypoxia/reoxygenation-derived exosomes had different protein content. Finally, ROS inhibition reduced exosome production but did not completely inhibit it. In conclusion, exosomal protein content is influenced by the cell source and stimulus for exosome formation. ROS stimulate exosome production. The functions of exosomes remain to be fully elucidated.

Improved Metabolic Control in Diabetes, HSP60, and Proinflammatory Mediators

The diabetes-atherosclerosis relationship remains to be fully defined. Repeated prolonged hyperglycemia, increased ROS production and endothelial dysfunction are important factors. One theory is that increased blood levels of heat shock protein (HSP)60 are proinflammatory, through activation of innate immunity, and contribute to the progression of vascular disease. It was hypothesized that improvement of diabetes control in patients presenting with metabolic syndrome would lower HSP60, and anti-HSP60 antibody levels and decrease inflammatory markers. Paired sera of 17 Italian patients, before and after intensive treatment, were assayed for cytokines, HSP60 and anti-HSP60 antibodies. As expected, intensive treatment was associated with a decrease in HgbA1C (P < 0.001) and BMI (P < 0.001). After treatment, there was a significant decrease in IL-6 (P < 0.05). HSP60 levels were before treatment −6.9 + 1.9, after treatment −7.1 + 2.0 ng/mL (P = ns). Overall HSP60 concentrations were lower than published reports. Anti-HSP60 antibody titers were high and did not decrease with treatment. In conclusion, improvement of diabetic control did not alter HSP60 concentrations or antiHSP60 antibody titers, but led to a reduction of IL-6 levels.

Metformin induced expression of Hsp60 in human THP-1 monocyte cells

Metformin is in widespread clinical use for the treatment of diabetes mellitus in patients. It has been shown to inhibit mitochondrial bioenergetic functions by inhibiting complex I of the electron transport chain. The expression of mitochondrial-specific molecular stress protein Hsp60 is a key consequence of mitochondrial impairment. Since this protein has important immune-modulatory properties, we have investigated the expression of Hsp60 in human THP-1 monocyte cells exposed to metformin. In this study, we demonstrate significant up-regulation of Hsp60 at both mRNA and protein levels when these cells were exposed to metformin at therapeutic dosage levels. Interestingly, there was also an increase in expression of CD14 mRNA in these cells. This suggested a possible modulation of the differentiation rates of the THP-1 cells during exposure to metformin. As monocyte differentiation marks a critical step in atherosclerosis, these observations suggest that long-term exposure to metformin could have important implications for the diabetic patient.

Detection of Hsp60 in saliva and serum from type 2 diabetic and non-diabetic control subjects

There is increasing evidence that mitochondrial dysfunction and oxidative stress may be integral to the pathogenesis of type 2 diabetes mellitus. Heat shock protein (Hsp60) is a mitochondrial stress protein known to be induced under conditions of mitochondrial impairment. Although this intracellular protein is normally found in the mitochondrion, several studies have shown that this protein is also present in systemic circulation. In this study, we report the presence of elevated levels of Hsp60 in both saliva and serum of type 2 diabetic patients compared to non-diabetic controls. Hsp60 was detectable in the saliva of 10% of control and 93% of type 2 diabetic patients. Levels detected were in the range of 3-7 ng/ml in control and 3-75 ng/ml in type 2 diabetic patients. Serum Hsp60 levels in the range of 3-88 ng/ml were detected in 33% of control subjects, and levels in the range of 28-1,043 ng/ml were detected in 100% of type 2 diabetic patients. This is the first reporting of the presence of mitochondrial stress protein in salivary secretions. The serum Hsp60 levels were 16-fold higher compared to those in saliva, and there was a good positive correlation between salivary and serum Hsp60 levels (r = 0.55). While the exact mechanisms responsible for the secretion of Hsp60 into biological fluids such as saliva and blood are not yet known. The presence of this molecular marker of mitochondrial stress in saliva offers a non-invasive route to further investigate the biological functions of extracellular Hsp60 in type 2 diabetes mellitus and other conditions.

Comparison of tear proteins between healthy and early diabetic retinopathy patients

OBJECTIVES

To identify potential prognostic or diagnostic marker tear proteins for early diabetic retinopathy (DR) and to investigate the pathogenesis of this disease using proteomics techniques.

DESIGN AND METHODS

The tear proteins expressed in patients suffering from diabetes mellitus without the retinopathy symptoms, nonproliferative diabetic retinopathy and healthy volunteers were analyzed by 2-DE. The differentially expressed proteins in patients were identified by ESI-Q-TOF and confirmed by Western blotting.

RESULTS

Proteins which were differentially expressed with statistical significance (P<0.05) in two diabetic groups as compared to those in healthy group were selected and identified by ESI-Q-TOF MS/MS. Among these proteins, three proteins (LCN-1, HSP27 and B2M) were found to exhibit a progressive reduction in two disease groups. The expression levels of which might be useful as diagnostic biomarkers of DR were verified by Western blotting

CONCLUSIONS

Proteomic analysis using tear is a novel approach that can provide insight into possible biomarker and the pathogenesis of early DR.

Proteomic analysis of circulating human monocytes in coronary artery disease

Monocytes play an important role in inflammation and atherosclerosis; however, the molecular details underlying these diverse functions are not completely understood. Proteomic analysis of monocytes can provide new insights into their biological role in coronary artery disease (CAD). Twenty angiographically confirmed male, CAD patients (≥50% stenosis) attending cardiology clinic of Nehru Hospital, PGIMER, Chandigarh, and who were not receiving any lipid lowering therapy and 20 TMT negative subjects who served as controls were enrolled in the study. Circulating monocytes isolated from overnight fasting blood samples were analyzed by 2D gel electrophoresis (pH 4-7), and differentially expressed protein spots were subjected to mass spectrometry and identification of proteins. We observed 333 ± 40 protein spots in monocytes from patients and 312 ± 20 in controls; out of which 63 protein spots showed altered intensity in CAD patients. Thirteen spots showed fivefold increased and two protein spots showed fivefold decreased expression in CAD group as compared to control group, respectively. Two proteins showing decreased expression in monocytes from CAD patients were identified as: (i) glutathione transferase and (ii) heat shock protein 70 KDa. Proteins showing increased expression in CAD patients were identified as: (i) vimentin, (ii) mannose binding lectin receptor protein, and (iii) S100A8 calcium-binding protein. The results of our study offer identification of several proteins in monocytes which can provide new perspectives in role of monocytes in pathogenesis of atherosclerosis.

Hsp60 and heme oxygenase-1 (Hsp32) in acute myocardial infarction

Heat shock proteins (Hsps) are produced in response to various stressors, including ischemia-reperfusion, and they can exit cells and reach the blood. In this pilot study, we determined serum levels of Hsp60 and heme-oxygenase-1 (HO-1; also named Hsp32) in subjects with acute myocardial infarction (AMI) to assess their clinical significance and potential prognostic value. We also performed a bioinformatics analysis of the 2 molecules in search of structural clues on the mechanism of their release from cells. We studied 40 patients consecutively admitted for AMI (male:female patient ratio=20:20, mean age: 64 ± 13 years) and 40 matched controls. A blood sample was drawn for biochemical analyses within 24 h of symptoms onset, and Hsp60 and HO-1 concentrations were determined by enzyme-linked immunosorbent assay (ELISA). All patients were followed up for 6 months to register adverse post-AMI cardiovascular events. A multivariate analysis demonstrated that elevated Hsp60 (P=0.0361), creatine phosphokinase-muscle brain (CK-MB) (P=0.0446), and troponin (P=0.0490) were predictive of post-AMI adverse events. In contrast, increased HO-1 showed a significant association with less severity of coronary artery diseases (P=0.0223). These findings suggest that Hsp60 and HO-1 play distinct roles in the pathogenesis of AMI and subsequent AMI-related pathology. The possibility that these proteins differ in their roles and mechanisms of action in AMI and post-AMI pathology was supported also by the bioinformatics estimates of probability of their localization in various subcellular compartments. The results clear the way for subsequent investigation on the pathogenetic role and clinical significance of Hsp60 and HO-1 in AMI.

The potential role of heat shock protein 27 in cardiovascular disease

Heat shock proteins (Hsps) comprise several families of proteins expressed by a number of cell types following exposure to stressful environmental conditions that include heat, free radicals, toxins and ischemia, and are particularly involved in the recognition and renaturation of mis-folded proteins. Heat shock protein-27 (Hsp27) is a member of the small Hsp (sHsp) family with a molecular weight of approximately 27 KDa. In addition to its chaperoning functions, Hsp27 also appears to be involved in a diverse range of cellular functions, promoting cell survival through effects on the apoptotic pathway and plays important roles in cytoskeleton dynamics, cell differentiation and embryogenesis. Over the past two decades there has been an increasing interest in the relationship between Hsp27 and cardiovascular disease. Hsp27 is thought to exert an important role in the atherosclerotic process. Serum Hsp27 concentrations appear to be a biomarker of myocardial ischemia. In this review, we will focus on the possible protective and immuno-modulatory roles of Hsp27 in atherogenesis with special emphasis on their changes following acute coronary events and their potential as diagnostic and therapeutic targets.

The effect of balneotherapy on C-reactive protein, serum cholesterol, triglyceride, total antioxidant status and HSP-60 levels

An increasing body of evidence substantiating the effectiveness of balneotherapy has accumulated during recent decades. In the present study, 42 ambulatory patients (23 males and 19 females, mean age 59.5 years) with degenerative musculoskeletal disease were randomised into one of two groups-bathing in tap water or in mineral water at the same temperature-and subjected to 30-min balneotherapy sessions on 15 occasions. Study parameters comprised serum levels of sensitised C-reactive protein (CRP), plasma lipids, heat shock protein (HSP-60) and total antioxidant status (TAS). In both groups, CRP levels followed a decreasing tendency, which still persisted 3 months later. At 3 months after balneotherapy, serum cholesterol levels were still decreasing in patients who had used medicinal water, but exhibited a trend towards an increase in the control group. Triglyceride levels followed a decreasing trend in both patient groups. TAS showed a declining tendency in both groups. No changes of HSP-60 levels were observed in either group. Balneotherapy with the thermal water from Hajdúszoboszló spa had a more pronounced physiological effect compared to that seen in the control group treated with tap water in a 3 month period.

Heat-shock protein 60 and cardiovascular disease: a paradoxical role

Heat-shock proteins (HSPs) are members of a highly conserved group of proteins that are induced in response to stress and injury. These proteins have protective properties, and can protect the heart from injury. HSP60 is found in the mitochondria and cytosol, and has essential intracellular functions including folding key proteins after their import into the mitochondria. In the cytosol, HSP60 binds to proapoptotic proteins, sequestering them. HSPs are highly conserved and, thus, are similar to bacterial proteins. Many individuals have antibodies to HSP60, possibly from prior infections. HSP60 can be found in the plasma membrane and in the serum in disease states. Serum HSP60 may be a marker for coronary artery disease. Once extracellular, HSP60 can cause cell injury. Thus, this protein has dichotomous functions for which the role in disease remains to be fully elucidated.

Is heat shock protein 60 associated with type 2 diabetes mellitus?

AIMS

HSP60 plays a protective role against heat, oxidative injury and ultraviolet. Recently, animal and clinical studies have suggested that HSP60 plays a role in various diseases. However, few epidemiological studies have demonstrated an association between HSP60 levels and type 2 diabetes mellitus. Therefore, an epidemiological study was conducted to examine the association of HSP60 with type 2 diabetes mellitus.

METHODS

This study included 83 type 2 diabetes mellitus patients and 161 controls that were recruited from male employees who received annual health check-ups between 2005 and 2007. The serum HSP60 levels were measured using the ELISA method.

RESULTS

Because the HSP60 levels were not detectable (<3.125 ng/mL) in 48.0% of the study subjects, HSP60 levels were divided into two categories (detectable or undetectable). A logistic regression analysis showed that the subjects in the undetectable had a 2.03 times higher risk of diabetes mellitus than those in the detectable after adjustment for age, BMI and rate of hypertension medication.

CONCLUSIONS

This study was the first epidemiological study to demonstrate an association between type 2 diabetes mellitus and HSP60, thus suggesting that HSP60 may play an important role in the type 2 diabetes mellitus pathology.

Elevated heat shock protein 60 levels are associated with higher risk of coronary heart disease in Chinese

BACKGROUND

Although heat shock protein 60 (Hsp60) is implicated in the pathogenesis of atherosclerosis, its role in coronary heart disease (CHD) is uncertain. This study explored the influence of circulating Hsp60 on CHD in a large case-control study, as well as the impact of acute myocardial infarction on Hsp60 levels in a prospective study.

METHODS AND RESULTS

Plasma Hsp60 and anti-Hsp60 antibody levels were determined by immunoassay. In the case-control study (1003 patients with CHD, 1003 matched control subjects), Hsp60 levels were higher in patients with CHD and were related to CHD (OR comparing extreme quartiles=4.14, P<0.0001). This association remained after adjustment for traditional risk factors (P for trend <0.0001). Individuals having high levels of Hsp60 (greater than the median of 160.24 ng/mL) and anti-Hsp60 antibody (greater than the median of 38.42 U/mL) were at a greater risk of CHD than those with low levels (OR 2.30, P<0.0001). Stronger additive effects (OR 14.04, P<0.0001) were apparent at higher Hsp60 and anti-Hsp60 antibody levels (>1000 ng/mL and greater than the median of 38.42 U/mL, respectively). The simultaneous presence of high Hsp60 and anti-Hsp60 antibody levels, current smoking, hypertension, and diabetes were cumulatively associated with CHD. Individuals who had any 4 or more of these 5 factors had an OR of 38.61 for CHD (P<0.0001) compared with individuals who had none of these factors. For the prospective study, blood was drawn from 20 patients immediately after admission for acute myocardial infarction and 2, 3, and 7 days thereafter. Hsp60 levels were significantly higher on the day of and the day after arrival than 7 days after an acute myocardial infarction (P=0.011 and P=0.026, respectively).

CONCLUSIONS

Elevated Hsp60 levels are associated with an increased risk for CHD, and Hsp60 and anti-Hsp60 antibody levels combine to increase this risk. In addition, acute myocardial infarction induces Hsp60 release.

Relation of serum heat shock protein 60 level to severity and prognosis in chronic heart failure secondary to ischemic or idiopathic dilated cardiomyopathy

Heat shock protein (HSP) 60 is induced by a variety of stressors, including oxidative stress and inflammation, and it plays a protective role against stress-induced cardiomyocyte injury. Recently, it has been reported that HSP 60 exists in the circulation. Chronic heart failure (CHF) is characterized by systemic abnormalities, and the myocardium is exposed to various stressors. However, the clinical significance of serum HSP 60 has not been examined in CHF. Therefore, the purpose of this study was to examine whether HSP 60 is correlated with the severity of CHF and whether HSP 60 can predict clinical outcomes in patients with CHF. Serum HSP 60 levels were measured in 112 patients with CHF and 62 control subjects. Serum HSP 60 levels were higher in patients with CHF than in control subjects and increased with advancing New York Heart Association functional class. There were 37 cardiac events during a mean follow-up period of 569 +/- 476 days (range 17 to 1,986). Serum HSP 60 levels were higher in patients with cardiac events than in event-free patients. Patients were divided into 4 groups on the basis of HSP 60 level. Cox proportional-hazards regression analysis and Kaplan-Meier analysis revealed that the fourth quartile was associated with the greatest risk for cardiac events. In conclusion, serum HSP 60 level was related to the severity of CHF and associated with a high risk for adverse cardiac events in patients CHF.

Heat shock protein 60 induces inflammatory mediators in mouse adipocytes

Adipocytes represent an important cellular source of inflammatory mediators. However, the signals for the induction of proinflammatory adipocyte activities are largely unknown. Here, we demonstrate that heat shock protein (Hsp) 60, a potent stimulator of innate immunity, induces the release of the inflammatory mediators interleukin-6, CXCL1 and monocyte chemoattractant protein-1 in a time- and concentration-dependent manner from cells of the adipocyte line 3T3-L1 and from adipocytes of obese mice. These results identify Hsp60 as an important regulator of adipocyte functions which contribute to the development of inflammatory processes as observed in diabetes and diabetes-associated complications.

Joint Effects of Antibody to Heat Shock Protein 60, Hypertension, and Diabetes on Risk of Coronary Heart Disease in Chinese

Background: Several studies have suggested an association between antibody to human heat shock protein 60 (anti-Hsp60) and coronary atherosclerosis, but the results have been inconsistent. The aim of this study was to investigate the association between anti-Hsp60 and coronary heart disease (CHD) and to determine whether anti-Hsp60, hypertension, and diabetes have joint effects on CHD risk.

Methods: We measured the concentrations of anti-Hsp60 in 1003 CHD patients and 1003 age- and sex-matched control subjects without CHD events.

Results: Concentrations of anti-Hsp60 were significantly higher in CHD patients than in controls. Increasing concentrations of anti-Hsp60 were significantly associated with higher risk of CHD (P for trend &lt;0.0001) and with increasing severity of CHD as assessed by number of diseased vessels detected with angiography [odds ratio (OR) 3.67, 95% CI 1.56–8.64, P = 0.003] after multivariate adjustment for traditional CHD risk factors. There were strong joint effects of high concentrations of anti-Hsp60 and hypertension (OR 5.17, 95% CI 3.95–6.75, P &lt; 0.0001) and diabetes (OR 6.49, 95% CI 4.52–9.33, P &lt; 0.0001) on CHD risk; simultaneous occurrence of high anti-Hsp60 concentrations, hypertension, and diabetes conferred a dramatically higher risk of CHD (OR 20.99, 95% CI 12.50–35.24, P &lt; 0.0001) in multivariate analyses.

Conclusions: Anti-Hsp60 is independently associated with CHD risk, and a combination of high anti-Hsp60, hypertension, and diabetes is particularly detrimental for CHD risk.

The autoimmune origin of atherosclerosis

Atherosclerosis is a chronic inflammatory disease. Many studies and observations suggest that it could be caused by an immune reaction against autoantigens at the endothelial level, the most relevant of which are oxidized LDL and heat shock proteins (HSP) 60/65. Endothelial dysfunction plays a fundamental role. The first antigen is related to the increased leakage and oxidation of LDL; the second to cellular reaction to stress. Experimental and clinical observations confirm the pathogenetic role of these antigens. Both innate and adaptive immunity and impaired regulatory mechanisms of the autoimmune reaction are involved. Different triggering factors are examined: infectious agents, smoking, air pollution, diabetes and hypercholesterolemia. Analogies and differences between systemic atherosclerosis and transplant-related coronary atherosclerosis help to understand their respective nature. Immune mechanisms might be responsible for the passage from stable plaque to unstable and rupture-prone plaque. Finally, prospects of treatment and prevention are linked to the induction of tolerance to responsible antigens, activation of immune regulatory response and the use of immunomodulatory drugs.

Plasma heat shock protein 60 and cardiovascular disease risk: the role of psychosocial, genetic, and biological factors

The Whitehall Study is a prospective epidemiological study of cardiovascular risk factors in healthy members of the British Civil Service, which has identified psychological distress as a major risk factor for coronary heart disease. The levels of circulating Hsp60 in 860 participants from the Whitehall cohort and 761 individuals diagnosed with diabetes have been measured and related to psychological, biological, and genetic factors. In the Whitehall participants, concentrations of Hsp60 ranged from undetectable to mg/mL levels. Circulating Hsp60 correlated with total and low-density lipoprotein (LDL) cholesterol and was positively associated with a flattened slope of cortisol decline over the day. Levels of this stress protein also correlated with measures of psychological stress including psychological distress, job demand, and low emotional support. Mass spectrometric analysis of circulating immunoreactive Hsp60 reveal that it is predominantly the intact protein with no mitochondrial import peptide, suggesting that this circulating protein emanates from mitochondria. The Hsp60 is stable when added to plasma and the levels in the circulation of individuals are remarkably constant over a 4-year period, suggesting plasma levels are partly genetically controlled. Sequence analysis of the HSP60-HSP10 intergenic promoter region identified a common variant 3175 C>G where the G allele had a frequency of 0.30 and was associated with higher Hsp60 levels in 761 type 2 diabetic patients. The extended range of plasma Hsp60 concentrations in the general population is genuine and is likely to be related to genetic, biological, and psychosocial risk factors for coronary artery disease.

Characterization of human mesenchymal stem cell secretome at early steps of adipocyte and osteoblast differentiation

Background

It is well established that adipose tissue plays a key role in energy storage and release but is also a secretory organ and a source of stem cells. Among different lineages, stem cells are able to differentiate into adipocytes and osteoblasts. As secreted proteins could regulate the balance between both lineages, we aimed at characterizing the secretome of human multipotent adipose-derived stem cell (hMADS) at an early step of commitment to adipocytes and osteoblasts.

Results

A proteomic approach, using mono-dimensional electrophoresis and tandem mass spectrometry, allowed us to identify a total of 73 proteins at day 0 and day 3 of adipocyte and osteoblast differentiation. Analysis of identified proteins showed that 52 % corresponded to classical secreted proteins characterized by a signal peptide, that 37 % previously described in the extracellular compartment were devoid of signal peptide and that 11 % neither exhibited a signal peptide nor had been previously described extracellularly. These proteins were classified into 8 clusters according to their function. Quantitative analysis has been performed for 8 candidates: PAI-1, PEDF, BIGH3, PTX3, SPARC, ENO1, GRP78 and MMP2. Among them, PAI-1 was detected at day 0 and day 3 of osteoblast differentiation but never in adipocyte secretome. Furthermore we showed that PAI-1 mRNA was down-regulated in the bone of ovariectomized mice.

Conclusion

Given its regulation during the early events of hMADS cell differentiation and its status in ovariectomized mice, PAI-1 could play a role in the adipocyte/osteoblast balance and thus in bone diseases such as osteoporosis.

Identification by a differential proteomic approach of the induced stress and redox proteins by resveratrol in the normal and diabetic rat heart

A recent study showed cardioprotective effects of resveratrol on the diabetic heart. The present study sought to compare the protein profiles of the normal versus diabetic hearts after resveratrol treatment using differential proteomic analysis. Rats were randomly divided into two groups: control and diabetic. Both groups of rats were fed resveratrol (2.5 mg/kg/day) for 7 days, and then the rats were sacrificed, hearts were isolated and cytoplasmic fraction from left ventricular tissue was collected to carry out proteomic profiling as well as immunoblotting. Compared to normal hearts, diabetic hearts show increased myocardial infarct size and cardiomy-ocyte apoptosis upon ex vivo global ischaemia of 30 min. followed by 2 hrs of reperfusion. Resveratrol reduced infarct size and apop-totic cell death for both the groups, but the extent of infarct size and apoptosis remained higher for the diabetic group compared to the normal group. The left ventricular cytoplasmic proteins were analysed by 2D-DIGE and differentially displayed bands were further analysed by nano Liquid Chromatography-Mass Spectroscopy (LC-MS/MS). The results showed differential regulation of normal versus diabetic hearts treated with resveratrol of many proteins related to energy metabolism of which several were identified as mitochondrial proteins. Of particular interest is the increased expression of several chaperone proteins and oxidative stress and redox proteins in the diabetic group including Hsc70, HSPp6, GRP75, peroxiredoxin (Prdx)-1 and Prdx-3 whose expression was reversed by resveratrol. Western blot analysis was performed to validate the up- or down-regulation of these stress proteins. The results indicate the differential regulation by resveratrol of stress proteins in diabetic versus normal hearts, which may explain in part the beneficial effects of resveratrol in diabetic induced cardiovascular complications.

Differential regulation of circulating levels of molecular chaperones in patients undergoing treatment for periodontal disease

Background

Evidence is emerging that molecular chaperones, in addition to their intracellular protein folding actions, can act as intercellular signaling proteins with an ability to modulate leukocyte function. Recent evidence has also shown that these proteins can exist in the circulation and may be involved in disease pathogenesis. We have used periodontitis and its treatment as a model of inflammation in the human to determine its effects on levels of circulating HSP10, HSP60 and BiP.

Methodology/Principal Findings

A group of periodontal patients and matched controls were examined at the beginning of the study and then at 1 day and 6 months following periodontal or control therapy. Plasma levels of HSP10, HSP60 and BiP were measured by immunoassay and related to other plasma measures of inflammation. Periodontal patients had significantly less circulating levels of HSP10 or BiP compared with the controls. In contrast, more periodontal patients had intermediate levels of HSP60. Treatment of the periodontitis caused an increase in plasma levels of HSP10 although it had no effect on BiP. Treatment had no influence of HSP60 levels. Plasma HSP10 levels after therapy correlated with markers of periodontal clinical improvement.

Conclusions/Significance

Circulating levels of molecular chaperones are influenced by local inflammation. HSP10 is known to be an anti-inflammatory factor. The marked decrease of this circulating protein in active inflammation and its recovery post-treatment suggests that it may have a role in controlling periodontal inflammation.

Circulating human monocytes in the acute coronary syndrome express a characteristic proteomic profile

We examined the proteome of circulating monocytes of patients with acute coronary syndrome at different times in comparison to that of patients with stable coronary artery disease. On admission, the expression of 18 spot proteins was altered, 10 of which were totally absent. This pattern changed progressively, and at 6 months, there were no differences with the monocyte proteome of stable patients.

Protective effect of human heat shock protein 60 suggested by its association with decreased seropositivity to pathogens

The presence of heat shock protein 60 (Hsp60) in human plasma has been linked with cardiovascular disease (CVD). In this study, the examination of the relationship between Hsp60 in plasma and seropositivity for three microbial agents, which are thought to be risk factors for CVD, surprisingly revealed a negative association between Hsp60 and seropositivity, suggesting a protective effect of this circulating stress protein.