Ag Pockley

Detection of heat shock protein 70 (HSP70) and anti-HSP70 antibodies in the serum of normal individuals

Heat shock or stress proteins (Hsp) are typically regarded as being intracellular proteins that have a range of functions including the maintenance of cellular integrity. Members of the Hsp70 family of molecules have been implicated in the processing and presentation of antigen and the cross reactivity of lymphocytes specific for pathogen-derived heat shock proteins with self Hsp70 has been suggested to be an underlying cause of certain autoimmune diseases. This study reports the presence of soluble Hsp70 in the peripheral circulation of normal individuals. Concentrations of soluble Hsp70 in females were approximately twice those in males. Circulating anti-Hsp70 antibodies were detected in all individuals assessed, but there were no differences between males and females. However, there was a significant correlation between soluble Hsp70 concentration and antibody levels in males, but not females. The physiological role for circulating heat shock proteins is intriguing, but currently unknown. These findings extend our previous observations that Hsp60 is present in the peripheral circulation and support the proposition that soluble heat shock proteins may play a regulatory role in either the prevention or protection of pathophysiological processes involving inadvertent immunorecognition or cross-recognition of heat shock proteins.

Circulating Heat Shock Protein 60 Is Associated With Early Cardiovascular Disease

The phylogenetically conserved nature of heat shock proteins (Hsp) has led to the proposition that they may provide a link between infection and the inflammatory component to vascular disease. Hypertension is associated with atherosclerosis. Here, we measured circulating heat shock protein and heat shock protein antibody levels in association with borderline hypertension. Seventy-two men with borderline hypertension patients and 75 normotensive control subjects (diastolic blood pressure 85 to 94 and <80 mm Hg, respectively) were selected from a population-screening program. The levels of Hsp60; Hsp70; and anti-human Hsp60, anti-human Hsp70, and anti-mycobacterial Hsp65 antibodies were determined with enzyme immunoassay. The presence of carotid atherosclerosis and the intima-media thickness values were determined with ultrasonography. A major novel observation in this report was the detection of circulating Hsp60, which was present at a significantly enhanced level in patients with borderline hypertension. Furthermore, serum Hsp60 was associated with intima-media thicknesses (P<0.01). Anti-Hsp65 antibody levels were higher in borderline hypertension (P<0.001), whereas Hsp70 and anti-Hsp70 antibody levels did not differ. In contrast to anti-Hsp65 antibody, anti-Hsp60 antibody levels were lower in borderline hypertension (P<0.03), although the difference was quantitatively small. None of the parameters evaluated were associated with atherosclerosis, metabolic factors, or smoking. We identified elevated Hsp60 levels in patients with borderline hypertension and an association between early atherosclerosis and Hsp60 levels. The physiological role of Hsp60 release has yet to be defined, but given the proinflammatory properties, these proteins could be involved in the induction/progression of both hypertension and atherosclerosis, as well as being markers for early cardiovascular disease.

Serum Heat Shock Protein 70 Levels Predict the Development of Atherosclerosis in Subjects With Established Hypertension

Abstract—Although heat shock proteins (Hsp’s) are present in the sera of healthy individuals and at elevated levels in subjects with early cardiovascular disease, their physiologic role in and value for predicting the development and/or progression of atherosclerosis have not been evaluated. Serum was obtained from 218 subjects with established hypertension (diastolic pressure >95 mm Hg) before their enrollment in the European Lacidipine Study on Atherosclerosis. Hsp60 and Hsp70, and anti-human Hsp60, anti-human Hsp70, and anti-mycobacterial Hsp65 antibody levels were measured by enzyme immunoassay. As an indicator of the presence/progression of atherosclerosis, the means of the maximum intima-media (I-M) thicknesses in the far walls of common carotid arteries and bifurcations (CBMmax) were determined by ultrasonography at the time of enrollment and 4 years afterward. Increases in I-M thicknesses at follow-up were less prevalent in subjects having high serum Hsp70 levels (75th percentile) at the time of enrollment (odds ratio, 0.42; 95% confidence interval [CI], 0.22 to 0.8, P =0.008). Although a similar trend was observed for serum Hsp60 levels, this was not statistically significant (odds ratio, 0.6; 95% CI, 0.32 to 1.11, P =0.10). There was no relation between anti-Hsp antibody levels and changes in I-M thicknesses. The relation between Hsp70 levels and changes in I-M thickness was independent of age, atenolol or lacidipine treatment, smoking habits, and blood lipid levels. These findings indicate that circulating Hsp70 levels predict the development of atherosclerosis in subjects with established hypertension, and an intriguing possibility is that Hsp70 protects against or modifies the progression of atherosclerosis in this subject group.

The dual immunoregulatory roles of stress proteins

Stress proteins (SPs) from the heat shock and glucose-regulated protein families are abundant intracellular molecules that have powerful extracellular roles as immune modulators. Mammalian immune cells encounter both identical (self) SPs and non-identical SPs derived from invading pathogens. Although such extracellular SPs can function as powerful immunological adjuvants, SPs, including Hsp60 and Hsp70, can also attenuate inflammatory disease via apparent effects on immunoregulatory T cell populations. It therefore seems that the immunostimulatory and immunosuppressive potential of extracellular SPs depends on the context in which they are encountered by the cellular immune-response network. Conclusions regarding the immunobiology of these powerful immunomodulatory molecules must therefore take into account their dichotomous properties and their physiological role and importance must be interpreted in the context of the complex in vivo microenvironments in which these proteins exist.

Leptin Indirectly Activates Human Neutrophils via Induction of TNF-α

Leptin, the satiety hormone, appears to act as a link between nutritional status and immune function. It has been shown to elicit a number of immunoregulatory effects, including the promotion of T cell proliferative responses, and the induction of proinflammatory cytokines. Leptin deficiency is associated with an increased susceptibility to infection. As polymorphonuclear neutrophils (PMN) play a major role in innate immunity and host defense against infection, this study evaluated the influence of leptin on PMN activation. The presence of leptin receptor in human PMN was determined both at mRNA and protein levels, and the effect of leptin on PMN activation, as assessed by CD11b expression, was evaluated using flow cytometry. In contrast to monocytes, which express both the short and long forms of the leptin receptor (Ob-Ra and Ob-Rb, respectively), PMN expressed only Ob-Ra. Leptin up-regulated the expression of CD11b, an early marker of PMN activation, on PMN in whole blood, yet it had no effect on purified PMN, even those treated by submaximal doses of TNF-α or PMA. The kinetics of leptin-induced activation in whole blood were consistent with an indirect effect mediated by monocytes, and 71% of the leptin-stimulatory effect on PMN was blocked by a TNF-α inhibitor. Leptin-mediated induction of CD11b expression was observed when purified PMN were coincubated with purified monocytes. In conclusion, although leptin activates PMN, it does so indirectly via TNF-α release from monocytes. These findings provide an additional link among the obesity-derived hormone leptin, innate immune function, and infectious disease.

Circulating heat shock protein and heat shock protein antibody levels in established hypertension

Objective Serum Hsp60 and anti-Hsp65 antibody levels are raised in subjects with borderline hypertension, and there is an association between circulating Hsp60 levels and early atherosclerosis. Given the recognized relationship between hypertension and atherosclerosis, this study determined heat shock protein and heat shock protein antibody levels in subjects with established hypertension. Methods Samples from 111 men with hypertension were obtained from the European Lacidipine study on Atherosclerosis and samples from 75 normotensive controls were taken from a population-screening programme (diastolic pressure, > 95 and < 80 mmHg, respectively). Hsp60, Hsp70 and anti-human Hsp60, anti-human Hsp70 and anti-mycobacterial Hsp65 antibody levels were measured by enzyme immunoassay. Intima–media thickness (I–M) and the presence of carotid atherosclerosis were determined by ultrasonography. Results Hsp60, Hsp70 and anti-Hsp60 antibody levels in hypertension were similar to those in normotensive controls, whereas anti-Hsp70 and anti-Hsp65 antibody levels were elevated (P < 0.001). Hsp60 levels and atherosclerosis were not associated. Anti-Hsp70 and anti-Hsp65 antibody levels were both associated with hypertension, independently of age, smoking habits and blood lipids. Conclusions This study demonstrates elevated levels of selected heat shock protein antibodies in subjects with hypertension. Although the association between heat shock protein antibody levels and human cardiovascular stress/disease appears to be robust, the relationship of the latter with heat shock protein levels is more complex. Further studies are required before the factors inducing, and the clinical significance of, circulating heat shock proteins can be evaluated.

Elevated levels of circulating heat shock protein 70 (Hsp70) in peripheral and renal vascular disease

Abstract Heat shock proteins (Hsp) are families of phylogenetically conserved molecules that have a range of cytoprotective and intracellular functional roles. Reactivity to heat shock proteins has been implicated in the development of autoimmune disease and tissue expression of heat shock proteins and increased levels of anti-Hsp antibodies have also been reported in vascular disease. This study compared circulating levels of Hsp60 and Hsp70 and antihuman Hsp60, antihuman Hsp70, and antimycobacterial Hsp65 antibodies in peripheral (PVD) and renal (RVD) vascular disease with those in age- and sex-matched controls. Levels of Hsp70 were higher in both PVD (median 580 vs 40; P < 0.01) and RVD (median 160 vs 0; P < 0.03), whereas there were no differences in Hsp60 levels. Anti-Hsp60 antibody levels were elevated in PVD (146 vs 81 arbitrary units/ml; P < 0.04), but not RVD. This is the first study to demonstrate increased levels of circulating Hsp70 in pathological disease states; however, its physiological role remains to be determined.

Serum heat shock protein and anti-heat shock protein antibody levels in aging.

We have previously reported the presence of Hsp60 and Hsp70 in the peripheral circulation of normal individuals. Given that the capacity to generate stress proteins declines with age, this study measured Hsp60 and Hsp70 levels in the sera of 60 individuals aged between 20 and 96 years. Levels of anti-human Hsp60, anti-human Hsp70 and anti-mycobacterial Hsp65 antibody were also measured. Senieur-approximated elderly subjects were well and randomly selected from the Belfast Elderly Longitudinal Free-living Aging STudy (BELFAST). Samples from younger individuals were obtained from the Northern Ireland Blood Transfusion Service. Hsp60, anti-Hsp60, anti-Hsp70 and anti-mycobacterial Hsp65 antibodies were detected in all samples, whereas Hsp70 was detectable in only 46 of the samples analysed (77%). Regression analysis revealed a progressive decline in Hsp60 (759ng/ml < 40 years; 294ng/ml > or = 90 years) and Hsp70 (400ng/ml < 40 years; 20ng/ml > or = 90 years) levels with age whereas no relationship was apparent for anti-Hsp60 and Hsp65 antibody levels. Hsp70 antibody levels tended to increase with age (115U/ml < 40 years; 191U/ml > or = 90 years). This study in Senieur-approximated subjects demonstrates an apparent decrease in Hsp60 and Hsp70 with increasing age that does not appear to be related to anti-heat shock protein antibody status. These findings support in vitro work that demonstrates an age-related reduced ability to respond to stress. Further studies are required to understand the basis for declining serum Hsp60 and Hsp70 levels in aging and to elucidate their origin and role in the maintenance of homeostasis and resistance to environmental challenges.

Targeting membrane heat-shock protein 70 (Hsp70) on tumors by cmHsp70.1 antibody

Immunization of mice with a 14-mer peptide TKDNNLLGRFELSG, termed “TKD,” comprising amino acids 450–461 (aa450–461) in the C terminus of inducible Hsp70, resulted in the generation of an IgG1 mouse mAb cmHsp70.1. The epitope recognized by cmHsp70.1 mAb, which has been confirmed to be located in the TKD sequence by SPOT analysis, is frequently detectable on the cell surface of human and mouse tumors, but not on isogenic cells and normal tissues, and membrane Hsp70 might thus serve as a tumor-specific target structure. As shown for human tumors, Hsp70 is associated with cholesterol-rich microdomains in the plasma membrane of mouse tumors. Herein, we show that the cmHsp70.1 mAb can selectively induce antibody-dependent cellular cytotoxicity (ADCC) of membrane Hsp70+ mouse tumor cells by unstimulated mouse spleen cells. Tumor killing could be further enhanced by activating the effector cells with TKD and IL-2. Three consecutive injections of the cmHsp70.1 mAb into mice bearing CT26 tumors significantly inhibited tumor growth and enhanced the overall survival. These effects were associated with infiltrations of NK cells, macrophages, and granulocytes. The Hsp70 specificity of the ADCC response was confirmed by preventing the antitumor response in tumor-bearing mice by coinjecting the cognate TKD peptide with the cmHsp70.1 mAb, and by blocking the binding of cmHsp70.1 mAb to CT26 tumor cells using either TKD peptide or the C-terminal substrate-binding domain of Hsp70.

Risk factors for atherosclerosis in cases with severe periodontitis

AIM Studies have reported on an association between cardiovascular disease (CVD) and periodontitis. The purpose of this case-control study was to provide an insight into this association by determining the plasma levels of some risk markers for CVD in cases with periodontitis. MATERIALS AND METHODS Sixty-eight cases with periodontitis, mean age 53.9 (SD 7.9) years, and 48 randomly selected healthy controls, mean age 53.1 (SD 7.9) years, were investigated. Fasting blood plasma was analysed for glucose, lipids, markers systemic inflammation, cytokines and antibodies against heat shock proteins (Hsp). The associations between periodontitis and the various substances analysed in plasma were calculated using a multivariate logistic regression model, which compensated for age, gender, smoking and body mass index. RESULTS The regression analyses revealed a significant association between periodontitis and high levels of C-reactive protein (CRP) [odds ratio (OR) 4.0, confidence interval (CI) 1.4-11.4] and fibrinogen (OR 8.7, CI 2.6-28.4), IL-18 (OR 6.5, CI 2.2-19.5), and decreased levels of IL-4 (OR 0.12, CI 0.0-0.5). The study showed increased levels of antibodies against Hsp65 (OR 2.8, CI 1-7.6) and 70 (OR 2.9, CI 1.1-7.8) and decreased levels of antibodies against Hsp60 (OR 0.3, CI 0.1-0.8). CONCLUSIONS Periodontitis was associated with increased levels of CRP, glucose, fibrinogen and IL-18, and with decreased levels of IL-4.