Heat shock protein 27 acts as a predictor of prognosis in chronic heart failure patients

The Role of Extracellular Heat Shock Proteins in Cardiovascular Diseases

In the early 1960s, heat shock proteins (HSPs) were first identified as vital intracellular proteinaceous components that help in stress physiology and reprogram the cellular responses to enable the organism's survival. By the early 1990s, HSPs were detected in extracellular spaces and found to activate gamma-delta T-lymphocytes. Subsequent investigations identified their association with varied disease conditions, including autoimmune disorders, diabetes, cancer, hepatic, pancreatic, and renal disorders, and cachexia. In cardiology, extracellular HSPs play a definite, but still unclear, role in atherosclerosis, acute coronary syndromes, and heart failure. The possibility of HSP-targeted novel molecular therapeutics has generated much interest and hope in recent years. In this review, we discuss the role of Extracellular Heat Shock Proteins (Ec-HSPs) in various disease states, with a particular focus on cardiovascular diseases.

Emerging role of heat shock proteins in cardiovascular diseases

Heat Shock Proteins (HSPs) are evolutionarily conserved proteins from prokaryotes to eukaryotes. They are ubiquitous proteins involved in key physiological and cellular pathways (viz. inflammation, immunity and apoptosis). Indeed, the survivability of the cells under various stressful conditions depends on appropriate levels of HSP expression. There is a growing line of evidence for the role of HSPs in regulating cardiovascular diseases (CVDs) (viz. hypertension, atherosclerosis, atrial fibrillation, cardiomyopathy and heart failure). Furthermore, studies indicate that a higher concentration of circulatory HSP antibodies correlate to CVDs; some are even potential markers for CVDs. The multifaceted roles of HSPs in regulating cellular signaling necessitate unraveling their links to pathophysiology of CVDs. This review aims to consolidate our understanding of transcriptional (via multiple transcription factors including HSF-1, NF-κB, CREB and STAT3) and post-transcriptional (via microRNAs including miR-1, miR-21 and miR-24) regulation of HSPs. The cytoprotective nature of HSPs catapults them to the limelight as modulators of cell survival. Yet another attractive prospect is the development of new therapeutic strategies against cardiovascular diseases (from hypertension to heart failure) by targeting the regulation of HSPs. Moreover, this review provides insights into how genetic variation of HSPs can contribute to the manifestation of CVDs. It would also offer a bird's eye view of the evolving role of different HSPs in the modulation and manifestation of cardiovascular disease.

Altered Heart Rate Turbulence and Variability Parameters Predict 1-Year Mortality in Heart Failure with Preserved Ejection Fraction

Background: Heart failure with preserved ejection fraction (HFpEF) is a complex and heterogeneous clinical syndrome. In the absence of effective and potent treatment strategies, the main challenge in HFpEF management remains the availability of strong predictors of unfavourable outcomes. In our study, we sought to evaluate the potential prognostic value of heart rate turbulence (HRT) and variability (HRV) parameters on mortality in ambulatory HFpEF patients. Methods: This was a case–control study comparing HRT and HRV parameters in HFpEF survivors vs. non-survivors. Patients from the RESPOND Heart Failure Registry with HFpEF who underwent 24 h ECG monitoring (Holter) were included; HRT parameters (i.e., turbulence onset (TO) and turbulence slope (TS)) and HRV parameters (i.e., standard deviation of NN intervals (SDNN)) derived from 24 h Holter ECGs were calculated in patients who died within 12 months, and compared to their age-, gender-, LVEF-, ECHO-, aetiology-, and therapy-matched alive controls. Results: A total of 22 patients (mean age 80 ± 7 years, 18% female, mean LVEF 57 ± 9%) were included in the final analysis. In deceased patients, values of TO were significantly higher, and values of TS and SDNN were significantly lower as compared to survivors. Conclusions: HRT and HRV parameters have the ability to differentiate individuals with HFpEF who are at the greatest risk of unfavourable outcomes. The extent of autonomic disbalance as determined by HRT and HRV could potentially assist in the prognostic assessment and risk stratification of HFpEF patients.

Role of ATP-Small Heat Shock Protein Interaction in Human Diseases

Adenosine triphosphate (ATP) is an important fuel of life for humans and Mycobacterium species. Its potential role in modulating cellular functions and implications in systemic, pulmonary, and ocular diseases is well studied. Plasma ATP has been used as a diagnostic and prognostic biomarker owing to its close association with disease’s progression. Several stresses induce altered ATP generation, causing disorders and illnesses. Small heat shock proteins (sHSPs) are dynamic oligomers that are dominantly β-sheet in nature. Some important functions that they exhibit include preventing protein aggregation, enabling protein refolding, conferring thermotolerance to cells, and exhibiting anti-apoptotic functions. Expression and functions of sHSPs in humans are closely associated with several diseases like cataracts, cardiovascular diseases, renal diseases, cancer, etc. Additionally, there are some mycobacterial sHSPs like Mycobacterium leprae HSP18 and Mycobacterium tuberculosis HSP16.3, whose molecular chaperone functions are implicated in the growth and survival of pathogens in host species. As both ATP and sHSPs, remain closely associated with several human diseases and survival of bacterial pathogens in the host, therefore substantial research has been conducted to elucidate ATP-sHSP interaction. In this mini review, the impact of ATP on the structure and function of human and mycobacterial sHSPs is discussed. Additionally, how such interactions can influence the onset of several human diseases is also discussed.

Traditional Chinese Medicine Targeting Heat Shock Proteins as Therapeutic Strategy for Heart Failure

Heart failure (HF) is the terminal stage of multifarious heart diseases and is responsible for high hospitalization rates and mortality. Pathophysiological mechanisms of HF include cardiac hypertrophy, remodeling and fibrosis resulting from cell death, inflammation and oxidative stress. Heat shock proteins (HSPs) can ameliorate folding of proteins, maintain protein structure and stability upon stress, protect the heart from cardiac dysfunction and ameliorate apoptosis. Traditional Chinese medicine (TCM) regulates expression of HSPs and has beneficial therapeutic effect in HF. In this review, we summarized the function of HSPs in HF and the role of TCM in regulating expression of HSPs. Studying the regulation of HSPs by TCM will provide novel ideas for the study of the mechanism and treatment of HF.

The inflammatory markers sST2, HSP27 and hsCRP as a prognostic biomarker panel in chronic heart failure patients

BACKGROUND

The inflammatory markers sST2, HSP27 and hsCRP have already been identified as prognostic markers in chronic heart failure (HF). Though individual biomarkers have proven their value in mortality risk prediction, the role of a multimarker strategy needs further evaluation.

MATERIALS AND METHODS

This is an exploratory reanalysis in chronic HF patients. Plasma HSP27, sST2 and hsCRP in outpatients with chronic HF were analysed. Patients were followed for a minimum of twelve months for the endpoint cardiovascular mortality and unplanned HF associated hospitalisation (=event). 15 year overall mortality was assessed retrospectively. The prognostic impact was assessed using a Cox proportional hazard model.

RESULTS

113 chronic HF patients were included. Median follow up time was 614 days and 37 patients (32.7%) experienced an event. A Kaplan-Meier analysis revealed that patients with increased sST2, HSP27 and hsCRP levels have significantly worse prognosis (p < 0.001). The use of a three-biomarker combination was superior in an independent risk prediction of an event (one high vs. two high: HR = 4.5, 95% CI: 1.3-15.5, p = 0.018; and one high vs. all high: HR = 9.8, 95% CI: 2.8-34.3, p < 0.001) as shown in a multivariable cox proportional hazard model. However, the biomarker panel did not predict 15 year overall mortality, in contrast to elevated HSP27 levels (p = 0.012).

CONCLUSIONS

The combination of all three markers is an independent predictor of cardiovascular death and unplanned HF associated hospitalisation but not overall mortality. Our findings suggest that adding those markers in combination to well established risk assessment parameters may improve risk stratification.

Systemic release of heat-shock protein 27 and 70 following severe trauma

Trauma represents a major cause of morbidity and mortality worldwide. The endogenous inflammatory response to trauma remains not fully elucidated. Pro-inflammation in the early phase is followed by immunosuppression leading to infections, multi-organ failure and mortality. Heat-shock proteins (HSPs) act as intracellular chaperons but exert also extracellular functions. However, their role in acute trauma remains unknown. The aim of this study was to evaluate serum concentrations of HSP 27 and HSP 70 in severely injured patients. We included severely injured patients with an injury severity score of at least 16 and measured serum concentration of both markers at admission and on day two. We found significantly increased serum concentrations of both HSP 27 and HSP 70 in severely injured patients. Concomitant thoracic trauma lead to a further increase of both HSPs. Also, elevated concentrations of HSP 27 and HSP 70 were associated with poor outcome in these patients. Standard laboratory parameters did not correlate with neither HSP 27, nor with HSP 70. Our findings demonstrate involvement of systemic release of HSP 27 and HSP 70 after severe trauma and their potential as biomarker in polytraumatized patients.

Endocan Is an Independent Predictor of Heart Failure-Related Mortality and Hospitalizations in Patients with Chronic Stable Heart Failure

Background

Heart failure (HF) is characterized by unfavorable prognosis. Disease trajectory of HF, however, may vary, and risk assessment of patients remains elusive. In our study, we sought to determine the prognostic impact of endocan—a novel biomarker of endothelial dysfunction and low-grade inflammation—in patients with heart failure.

Methods

In outpatients with chronic HF, baseline values of endocan were determined and clinical follow-up for a minimum of 18 months obtained. A multivariate Cox proportional hazard model was built for HF-related death or hospitalization requiring inotropic support.

Results

A total of 120 patients (mean age 71 years, 64% male, mean LVEF 36%) were included. During a mean follow-up of 656 ± 109 days, 50 patients (41.6%) experienced an event. On Cox multivariate analysis, endocan values emerged as an independent predictor of HF prognosis (HR, 1.471 CI 95% 1.183-1.829, p = 0.001, for each 1 ng/mL increase) even after adjustment for age, gender, HF etiology, LVEF, NYHA class, NT-proBNP, and exercise tolerance.

Conclusions

Endocan is an independent predictor of HF-related events in chronic HF individuals and represents a promising tool for risk assessment of HF patients.

Serum heat shock protein 27 levels predict cardiac mortality in hemodialysis patients

Background

Decreased heat shock protein 27 (HSP27) participates in many processes that are involved in cardiovascular (CV) disease. The objective of the study was to evaluate if HSP27 level was predictive of mortality as well as to evaluate factors associated with HSP27 level in a group of patients treated with HD.

Methods

Enrolled to the study were 202 HD patients. Clinical data, biochemical, echocardiographic, and carotid atherosclerosis parameters were evaluated. Patients were splited into groups on the basis of the cut-off lower and higher 50th percentile of serum HSP27 levels, and were followed-up for 28.68 ± 6.12 months.

Results

No significant difference was observed between serum HSP27 levels in patients and controls. Low HSP27 patients were older, had higher left ventricular mass index, lower ejection fraction, higher prevalence of diabetes, myocardial infarction and carotid atherosclerosis, higher C-reactive protein level, and worse oxidant/antioxidant status. The multiple regression analysis identified that HSP27 levels were independently, negatively associated with serum oxidized LDL and the number of carotid plaques. Using the Kaplan–Meier analysis it was shown that the cumulative incidences of both CV and sudden cardiac death (SCD) mortality were higher in low HSP27 group in comparison with high serum HSP27 group. A multivariate Cox analysis showed that HSP27 level is an independent and strong predictor of CV as well as SCD mortality.

Conclusions

Low serum HSP27 level is independently associated with both CV and SCD mortality but not with all-cause mortality. Low serum HSP27 level is associated with carotid atherosclerosis and oxidative stress.

Heat shock protein 70 promotes lipogenesis in HepG2 cells

Background

The increasing prevalence of non-alcoholic fatty liver disease (NAFLD) has followed the international rise in obesity rates. Multiple mechanisms are involved in NAFLD, including endoplasmic reticulum stress and oxidative stress. Heat shock protein 70 (HSP70), which is abundant in most organisms, is sensitive to stress. However, the role of HSP70 in NAFLD has not been investigated. Here, we investigated the possible role of HSP70 in lipid synthesis.

Methods

C57BL/6 mice were fed a high-fat diet, and HepG2 cells were treated with 0.5 mM palmitic acid (PA). HSP70 expression was detected by qPCR, Western blot and immunohistochemistry. Total cholesterol (TC) and triglyceride (TG) levels were detected by enzyme-linked immunosorbent assay (ELISA). After Hsp70 overexpression and knockdown, TC and TG levels and FAS, SCD, and ACC expression were detected.

Results

HSP70 expression was significantly increased in the livers of obese mice. In vitro, HSP70 expression was markedly induced by PA in HepG2 cells. Notably, HSP70 overexpression in HepG2 cells enhanced TC and TG synthesis, in parallel with the upregulation of lipogenic genes, including FAS, SCD and ACC. By contrast, HSP70 knockdown decreased the levels of cellular lipids and the expression of FAS, SCD, and ACC in HepG2 cells. Together, our results suggest that HSP70 may promote lipogenesis in HepG2 cells.

Conclusions

Heat shock protein 70 promotes lipogenesis in HepG2 cells.