Complement activating antibodies against the human 60 kDa heat shock protein as a new independent family risk factor of coronary heart disease

Impact of thermal stress on expression dynamics of HSP60 in cardiac fibroblast cells of goat

The present study was aimed to determine the impact of thermal stress on expression dynamics of heat shock protein 60 (HSP60) mRNA in cultured cardiac fibroblast cells of the goat. The heart tissues (n = 6) from different goats were used for the culture study. The cardiac fibroblast cells were cultured and subjected to thermal stress at 42 °C for 0, 20, 60 and 100 min. The relative abundance of HSP60 mRNA was assessed by quantitative real-time PCR (qRT-PCR). The cardiac cells exposed to thermal stress at 42 °C for 0 min was taken as control. The relative abundance of HSP60 mRNA did not change at 20 min of thermal stress as compared to control. Thereafter, the relative abundance of HSP60 mRNA was significantly up-regulated (p < 0.05) at 60 min and 100 min of thermal stress. However, the highest mRNA expression of HSP60 was noticed at 100 min of thermal stress. The present study indicates that, thermal stress modulates the mRNA expression HSP60 in cultured caprine cardiac fibroblast cells.

Heat Shock Proteins: Protection and Potential Biomarkers for Ischemic Injury of Cardiomyocytes After Surgery

The heat shock proteins are endogenous proteins with the ability to act as molecular chaperones. Methods that provide cell protection by way of some damage can positively influence the results of surgery. The present review summarizes current knowledge concerning the cardioprotective role of the heat shock proteins as occurs in heart damage, including relevant information about the stresses that regulate the expression of these proteins and their potential role as biomarkers of heart disease.

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.

Anti-Heat Shock Protein 27 Titers and Oxidative Stress Levels are Elevated in Patients With Valvular Heart Disease

We studied the immune responses to heat shock protein (Hsp)-27 and pro-oxidant–antioxidant balance (PAB) values in patients with valvular heart disease, but free of angiographically evident coronary artery disease (CAD). Patients who were candidates for valvuloplasty surgery and 30 healthy matched controls were recruited. The anti-Hsp-27 antibody titers were 0.35 ± 0.04 absorbency units (AU) in the valvuloplasty group, being significantly higher than for the controls (0.11 ± 0.02 AU; P < .05). The PAB values were significantly higher in cases (134.67 ± 13.69 Hamidi-Koliakos(HK) unit) when compared with controls (49.78 ± 6.75 HK unit; P < .05). In cases, the ejection fraction was inversely correlated with anti-Hsp-27 antibody ( P < .05) but was not significantly related to PAB values ( P > .05). Based on the echocardiographic findings, the patients had no evident heart failure, but the high levels of anti-Hsp-27 and PAB values in patients with valvular heart disease may indicate that these variables can be used as markers of heart failure. However, a longitudinal study is required to confirm this hypothesis.

The heat shock protein profile in children with chronic kidney disease

OBJECTIVES

Chronic kidney disease (CKD) due to inflammation, lipid disorders, and endothelial dysfunction predisposes to accelerated atherosclerosis. Elevated levels of heat shock proteins (HSPs) and antibodies against them have been described in adults with atherosclerotic lesions and cardiovascular events. However, there are no investigations of these variables in children with CKD treated conservatively or on peritoneal dialysis. Therefore, we decided to evaluate the profile of HSPs and their potential role as markers of atherosclerosis in these groups of patients.

METHODS

The study group consisted of 37 children with CKD treated conservatively and 19 children and young adults on automated peritoneal dialysis (APD). The control group comprised 15 age-matched subjects with normal kidney function. HSP-60, HSP-70, HSP-90alpha, anti-HSP-60, anti-HSP-70, sE-selectin, and interleukin (IL)-4 serum concentrations were assessed by ELISA; high-sensitivity C-reactive protein (hs-CRP) serum levels were assessed by nephelometry. Serum lipid profiles (total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, triglycerides) were also estimated.

RESULTS

HSP-90alpha, anti-HSP-60, and sE-selectin concentrations in the CKD and APD patients were higher than in the controls and were lower in the predialysis subjects than in the children on dialysis. Median values of anti-HSP-70 were higher in the CKD patients than in the control group. Levels of IL-4 were increased in all patients versus controls. Median values of HSP-60 were decreased in the CKD and APD children versus controls. HSP-70 and hs-CRP concentrations were comparable in all groups.

CONCLUSIONS

The altered HSP and anti-HSP concentrations may imply that the response to stress conditions in the course of CKD is disturbed in children; APD does not aggravate that dysfunction in a significant way. Relationships between HSPs, lipid profile, and markers of inflammation suggest a possible role of the selected HSPs as markers of atherosclerosis in children with CKD.

Immune-mediated mechanisms of endothelial damage in atherosclerosis

The endothelium of the vessel wall as a barrier between blood and the subendothelial matrix proteins is essential for preventing thrombus formation and subsequent atherosclerosis development. Atherosclerosis is an inflammatory disease in which immune and autoimmune mechanisms are involved. Recently, it was demonstrated that endothelial cells in the vessel wall can be damaged not only by classic risk factors, such as hyperlipidemia, smoking and disturbed blood flow, but also (auto)immune reactions to autoantigens present in the cell surface, among which heat shock protein 60 (HSP60) was mostly studied. HSP60 normally located in mitochondria can be translocated into the cell member in response to stress stimuli. Meanwhile, autoantibodies against HSP60 are present in most subjects, especially patients with heart attack and stroke. These autoantibodies may bind to HSP60 expressed in endothelial cells resulting in the cell damage, subsequently initiating the formation of atherosclerotic lesions. Based on the recent progress in the research field, the present review will update the mechanisms of immune response to endothelial cells by which cell damage can initiate the development of atherosclerosis.

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.

Circulating anti-heat-shock-protein antibodies in normal pregnancy and preeclampsia

It has been previously reported that circulating anti-heat-shock-protein (Hsp) antibody levels are elevated in cardiovascular disorders. The aim of the present study was to determine circulating antihuman Hsp60, antimycobacterial Hsp65, and antihuman Hsp70 antibody levels in healthy pregnant women and preeclamptic patients and to investigate their relationship to the clinical characteristics of the study subjects, as well as to the markers of inflammation (C-reactive protein (CRP)), endothelial activation (von Willebrand factor antigen), or endothelial injury (fibronectin), oxidative stress (malondialdehyde) and to serum Hsp70 levels. Ninety-three preeclamptic patients and 127 normotensive healthy pregnant women were involved in this case control study. Serum anti-Hsp60, anti-Hsp65, anti-Hsp70, and Hsp70 levels were measured with enzyme-linked immunosorbent assay (ELISA). Serum CRP levels were determined by an autoanalyzer using the manufacturer's kit. Plasma von Willebrand factor antigen levels were quantified by ELISA, while plasma fibronectin concentration by nephelometry. Plasma malondialdehyde levels were measured by the thiobarbituric-acid-based colorimetric assay. For statistical analyses, nonparametric methods were applied. Anti-Hsp60, anti-Hsp65, and anti-Hsp70 antibodies were detected in all of our serum samples. There were no significant differences in serum anti-Hsp60, anti-Hsp65, and anti-Hsp70 antibody levels between the control and preeclamptic groups. Serum levels of Hsp70 and CRP, as well as plasma levels of VWF antigen, fibronectin, and malondialdehyde, were significantly higher in preeclamptic patients than in normotensive healthy pregnant women. Serum anti-Hsp60 antibody levels showed significant correlations with serum anti-Hsp65 antibody levels both in the control and the preeclamptic groups (Spearman R = 0.55 and 0.59; p < 0.001, respectively). However, no other relationship was found between clinical features (maternal age, smoking status, parity, body mass index, gestational age at blood draw, systolic and diastolic blood pressure, gestational age at delivery, and fetal birth weight) and measured laboratory parameters of the study subjects and serum anti-Hsp antibody levels in either study group. In conclusion, anti-Hsp60 and anti-Hsp70 antibodies as naturally occurring autoantibodies are present in the peripheral circulation of healthy pregnant women. Nevertheless, humoral immunity against heat shock proteins was not associated with preeclampsia. Further studies are warranted to explore the role of heat shock proteins and immune reactivity to them in the immunobiology of normal pregnancy and preeclampsia.

Genetic variation in heat shock protein 60 gene and coronary heart disease in China: tagging-SNP haplotype analysis in a case-control study

BACKGROUND

High levels of circulating heat shock protein 60 (Hsp60) and antibody to human Hsp60 have been associated with greater risk of coronary heart disease (CHD) in several studies, but associations between polymorphisms of the hsp60 gene and CHD risk have not been investigated.

METHODS

By resequencing DNA from 30 unrelated Han Chinese and using HapMap Phase I Chinese data of hsp60 gene, we selected four tagging single nucleotide polymorphisms (tagSNPs) named rs2340690, rs788016, rs2305560, and rs2565163, and determined their frequencies in 1,003 Chinese CHD patients and 1,003 age- and sex-frequency-matched controls. Furthermore, we used PHASE 2.0 software to reconstruct haplotypes and logistic regression to control for potential confounders in multivariate analyses.

RESULTS

We found 13 SNPs in hsp60 gene (including four novel SNPs) in Han Chinese subjects. Our results showed no significant differences in four selected SNPs in patients with CHD and controls after adjusting for other conventional risk factors and stratifying by age, sex, smoking status, past history of hypertension and DM; however, our results showed that subjects with the GCTC haplotype had about twofold higher risk of CHD than those with the GTTC haplotype (OR = 1.91, 95%CI: 1.26-2.89, P = 0.002).

CONCLUSIONS

Our results suggest that the GCTC haplotype in the hsp60 gene is significantly associated with higher CHD risk in a Chinese population.

HSP60 in heart failure: abnormal distribution and role in cardiac myocyte apoptosis

Heat shock protein (HSP) 60 is a mitochondrial and cytosolic protein. Previously, we reported that HSP60 doubled in end-stage heart failure, even though levels of the protective HSP72 were unchanged. Furthermore, we observed that acute injury in adult cardiac myocytes resulted in movement of HSP60 to the plasma membrane. We hypothesized that the inflammatory state of heart failure would cause translocation of HSP60 to the plasma membrane and that this would provide a pathway for cardiac injury. Two models were used to test this hypothesis: 1) a rat model of heart failure and 2) human explanted failing hearts. We found that HSP60 localized to the plasma membrane and was also found in the plasma early in heart failure. Plasma membrane HSP60 localized to lipid rafts and was detectable on the cell surface with the use of both flow cytometry and confocal microscopy. Localization of HSP60 to the cell surface correlated with increased apoptosis. In heart failure, HSP60 is in the plasma membrane fraction, on the cell surface, and in the plasma. Membrane HSP60 correlated with increased apoptosis. Release of HSP60 may activate the innate immune system, promoting a proinflammatory state, including an increase in TNF-alpha. Thus abnormal trafficking of HSP60 to the cell surface may be an early trigger for myocyte loss and the progression of heart failure.

Antibodies against heat shock proteins in environmental stresses and diseases: friend or foe?

Heat shock proteins (Hsps) can be found in two forms, intracellular and extracellular. The intracellular Hsps are induced as a result of stress and have been found to be cytoprotective in many instances due to their chaperone functions in protein folding and in protein degradation. The origin and role of extracellular Hsps is less clear. Although they were suspected originally to be released from damaged cells (necrosis), their presence in most normal individuals rather suggests that they have regulatory functions in circulation. As immunodominant molecules, Hsps can stimulate the immune system, leading to the production of autoantibodies recognizing epitopes shared by microbial and human Hsps. Thus, extracellular Hsps can influence the inflammatory response as evidenced by the production of inflammatory cytokines. Antibodies to Hsps have been found under normal conditions but seem to be increased in certain stresses and diseases. Such antibodies could regulate the inflammatory response positively or negatively. Here, we review the literature on the findings of antibodies to Hsps in situations of environmental or occupational stress and in a number of diseases and discuss their possible significance for the diagnosis, prognosis, or pathogenesis of these diseases.

Heat shock proteins in cardiovascular disease and the prognostic value of heat shock protein related measurements

Are heat shock protein antibodies directly involved in the pathogenesis of cardiovascular disease?

Autoimmune and inflammatory mechanisms in atherosclerosis

The present review focuses on the concept that cellular and humoral immunity to the phylogenetically highly conserved antigen heat shock protein 60 (HSP60) is the initiating mechanism in the earliest stages of atherosclerosis. Subjecting arterial endothelial cells to classical atherosclerosis risk factors leads to the expression of HSP60 that then may serve as a target for pre-existent cross-reactive antimicrobial HSP60 immunity or bona fide autoimmune reactions induced by biochemically altered autologous HSP60. Endothelial cells can also bind microbial or autologous HSP60 via Toll-like receptors, providing another possibility for targetting adaptive or innate immunological effector mechanisms.

Immunological aspects of heat-shock proteins-the optimum stress of life

This review summarizes the complex role of heat-shock proteins (Hsp) in immune reactions, especially the cellular effects of heat-shock proteins during the recognition processes by innate immunity. The role of heat-shock proteins in the pathogenesis of two multifactorial diseases, i.e. inflammatory bowel disease (IBD) and atherosclerosis is highlighted. A new hypothesis on "immunodeficiency burden" is presented. According to this hypothesis, susceptibility to any multifactorial disease in any given subject and in the presence of specific environmental factors is the aggregate effect of polymorphisms resulting in the failure of protective immunity with consequent disease.