Heat-shock protein 90: A novel autoantigen in human carotid atherosclerosis

Fatal attractions that trigger inflammation and drive atherosclerotic disease

BACKGROUND

Atherosclerosis is the salient, underlying cause of cardiovascular diseases, such as arrhythmia, coronary artery disease, cardiomyopathy, pulmonary embolism and myocardial infarction. In recent years, atherosclerosis pathophysiology has evolved from a lipid-based to an inflammation-centric ideology.

METHODS

This narrative review is comprised of review and original articles that were found through the PubMed search engine. The following search terms or amalgamation of terms were used: "cardiovascular disease," "atherosclerosis," "inflammation," "GRP78," "Hsp60," "oxidative low-density lipoproteins," "aldehyde dehydrogenase," "β2-glycoprotein," "lipoprotein lipase A," "human cytomegalovirus." "SARS-CoV-2," "chlamydia pneumonia," "autophagy," "thrombosis" and "therapeutics."

RESULTS

Emerging evidence supports the concept that atherosclerosis is associated with the interaction between cell surface expression of stress response chaperones, including GRP78 and Hsp60, and their respective autoantibodies. Moreover, various other autoantigens and their autoantibodies have displayed a compelling connection with the development of atherosclerosis, including oxidative low-density lipoproteins, aldehyde dehydrogenase, β2-glycoprotein and lipoprotein lipase A. Atherosclerosis progression is also concurrent with viral and bacterial activators of various diseases. This narrative review will focus on the contributions of human cytomegalovirus as well as SARS-CoV-2 and chlamydia pneumonia in atherosclerosis development. Notably, the interaction of an autoantigen with their respective autoantibodies or the presence of a foreign antigen can enhance inflammation development, which leads to atherosclerotic lesion progression.

CONCLUSION

We will highlight and discuss the complex role of the interaction between autoantigens and autoantibodies, and the presence of foreign antigens in the development of atherosclerotic lesions in relationship to pro-inflammatory responses.

Endoplasmic reticulum stress-mediated cell death in cardiovascular disease

The endoplasmic reticulum (ER) plays a vital function in maintaining cellular homeostasis. Endoplasmic reticulum stress (ERS) can trigger various modes of cell death by activating the unfolded protein response (UPR) signaling pathway. Cell death plays a crucial role in the occurrence and development of diseases such as cancer, liver diseases, neurological diseases, and cardiovascular diseases. Several cardiovascular diseases including hypertension, atherosclerosis, and heart failure are associated with ER stress. ER stress-mediated cell death is of interest in cardiovascular disease. Moreover, an increasing body of evidence supports the potential of modulating ERS for treating cardiovascular disease. This paper provides a comprehensive review of the UPR signaling pathway, the mechanisms that induce cell death, and the modes of cell death in cardiovascular diseases. Additionally, we discuss the mechanisms of ERS and UPR in common cardiovascular diseases, along with potential therapeutic strategies.

lncRNA TUG1 as potential novel biomarker for prognosis of cardiovascular diseases

Globally, cardiovascular diseases (CVDs) are among the leading causes of death. In light of the high prevalence and mortality of CVDs, it is imperative to understand the molecules involved in CVD pathogenesis and the signaling pathways that they initiate. This may facilitate the development of more precise and expedient diagnostic techniques, the identification of more effective prognostic molecules and the identification of potential therapeutic targets. Numerous studies have examined the role of lncRNAs, such as TUG1, in CVD pathogenesis in recent years. According to this review article, TUG1 can be considered a biomarker for predicting the prognosis of CVD.

Shear stress induces monocyte/macrophage-mediated inflammation by upregulating cell-surface expression of heat shock proteins

The loss of endothelial cells is associated with the accumulation of monocytes/macrophages underneath the surface of the arteries, where cells are prone to mechanical stimulation, such as shear stress. However, the impact of mechanical stimuli on monocytic cells remains unclear. To assess whether mechanical stress affects monocytic cell function, we examined the expression of inflammatory molecules and surface proteins, whose levels changed following shear stress in human THP-1 cells. Shear stress increased the inflammatory chemokine CCL2, which enhanced the migration of monocytic cells and tumor necrosis factor (TNF)-α and interleukin (IL)- 1β at transcriptional and protein levels. We identified that the surface levels of heat shock protein 70 (HSP70), HSP90, and HSP105 increased using mass spectrometry-based proteomics, which was confirmed by western blot analysis, flow cytometry, and immunofluorescence. Treatment with HSP70/HSP105 and HSP90 inhibitors suppressed the expression and secretion of CCL2 and monocytic cell migration, suggesting an association between HSPs and inflammatory responses. We also demonstrated the coexistence and colocalization of increased HSP90 immunoreactivity and CD68 positive cells in atherosclerotic plaques of ApoE deficient mice fed a high-fat diet and human femoral artery endarterectomy specimens. These results suggest that monocytes/macrophages affected by shear stress polarize to a pro-inflammatory phenotype and increase surface protein levels involved in inflammatory responses. The regulation of the abovementioned HSPs upregulated on the monocytes/macrophages surface may serve as a novel therapeutic target for inflammation due to shear stress.

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.

Targeting extracellular Hsp90: A unique frontier against cancer

The molecular chaperone Heat Shock Protein-90 (Hsp90) is known to interact with over 300 client proteins as well as regulatory factors (eg. nucleotide and proteins) that facilitate execution of its role as a chaperone and, ultimately, client protein activation. Hsp90 associates transiently with these molecular modulators during an eventful chaperone cycle, resulting in acquisition of flexible structural conformations, perfectly customized to the needs of each one of its client proteins. Due to the plethora and diverse nature of proteins it supports, the Hsp90 chaperone machinery is critical for normal cellular function particularly in response to stress. In diseases such as cancer, the Hsp90 chaperone machinery is hijacked for processes which encompass many of the hallmarks of cancer, including cell growth, survival, immune response evasion, migration, invasion, and angiogenesis. Elevated levels of extracellular Hsp90 (eHsp90) enhance tumorigenesis and the potential for metastasis. eHsp90 has been considered one of the new targets in the development of anti-cancer drugs as there are various stages of cancer progression where eHsp90 function could be targeted. Our limited understanding of the regulation of the eHsp90 chaperone machinery is a major drawback for designing successful Hsp90-targeted therapies, and more research is still warranted.

Factors influencing the soluble guanylate cyclase heme redox state in blood vessels

Soluble guanylate cyclase (sGC) plays an important role in maintaining vascular homeostasis, as an acceptor for the biological messenger nitric oxide (NO). However, only reduced sGC (with a ferrous heme) can be activated by NO; oxidized (ferric heme) and apo (absent heme) sGC cannot. In addition, the proportions of reduced, oxidized, and apo sGC change under pathological conditions. Although diseased blood vessels often show decreased NO bioavailability in the vascular wall, a shift of sGC heme redox balance in favor of the oxidized/apo forms can also occur. Therefore, sGC is of growing interest as a drug target for various cardiovascular diseases. Notably, the balance between NO-sensitive reduced sGC and NO-insensitive oxidized/apo sGC in the body is regulated in a reversible manner by various biological molecules and proteins. Many studies have attempted to identify endogenous factors and determinants that influence this redox state. For example, various reactive nitrogen and oxygen species are capable of inducing the oxidation of sGC heme. Conversely, a heme reductase and some antioxidants reduce the ferric heme in sGC to the ferrous state. This review summarizes the factors and mechanisms identified by these studies that operate to regulate the sGC heme redox state.

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.

Heat Shock Proteins: Connectors between Heart and Kidney

Over the development of eukaryotic cells, intrinsic mechanisms have been developed in order to provide the ability to defend against aggressive agents. In this sense, a group of proteins plays a crucial role in controlling the production of several proteins, guaranteeing cell survival. The heat shock proteins (HSPs), are a family of proteins that have been linked to different cellular functions, being activated under conditions of cellular stress, not only imposed by thermal variation but also toxins, radiation, infectious agents, hypoxia, etc. Regarding pathological situations as seen in cardiorenal syndrome (CRS), HSPs have been shown to be important mediators involved in the control of gene transcription and intracellular signaling, in addition to be an important connector with the immune system. CRS is classified as acute or chronic and according to the first organ to suffer the injury, which can be the heart (CRS type 1 and type 2), kidneys (CRS type 3 and 4) or both (CRS type 5). In all types of CRS, the immune system, redox balance, mitochondrial dysfunction, and tissue remodeling have been the subject of numerous studies in the literature in order to elucidate mechanisms and propose new therapeutic strategies. In this sense, HSPs have been targeted by researchers as important connectors between kidney and heart. Thus, the present review has a focus to present the state of the art regarding the role of HSPs in the pathophysiology of cardiac and renal alterations, as well their role in the kidney–heart axis.

Apolipoprotein A-I mimetic peptide inhibits atherosclerosis by increasing tetrahydrobiopterin via regulation of GTP-cyclohydrolase 1 and reducing uncoupled endothelial nitric oxide synthase activity

BACKGROUND AND AIMS

The apolipoprotein A-I mimetic peptide D-4F, among its anti-atherosclerotic effects, improves vasodilation through mechanisms not fully elucidated yet.

METHODS

Low-density lipoprotein (LDL) receptor null (LDLr-/-) mice were fed Western diet with or without D-4F. We then measured atherosclerotic lesion formation, endothelial nitric oxide synthase (eNOS) phosphorylation and its association with heat shock protein 90 (HSP90), nitric oxide (NO) and superoxide anion (O2•-) production, and tetrahydrobiopterin (BH4) and GTP-cyclohydrolase 1 (GCH-1) concentration in the aorta. Human umbilical vein endothelial cells (HUVECs) and aortas were treated with oxidized LDL (oxLDL) with or without D-4F; subsequently, BH4 and GCH-1 concentration, NO and O2•- production, eNOS association with HSP90, and endothelium-dependent vasodilation were measured.

RESULTS

Unexpectedly, eNOS phosphorylation, eNOS-HSP90 association, and O2•- production were increased, whereas BH4 and GCH-1 concentration and NO production were reduced in atherosclerosis. D-4F significantly inhibited atherosclerosis, eNOS phosphorylation, eNOS-HSP90 association, and O2•- generation but increased NO production and BH4 and GCH-1 concentration. OxLDL reduced NO production and BH4 and GCH-1 concentration but enhanced O2•- generation and eNOS association with HSP90, and impaired endothelium-dependent vasodilation. D-4F inhibited the overall effects of oxLDL.

CONCLUSIONS

Hypercholesterolemia enhanced uncoupled eNOS activity by decreasing GCH-1 concentration, thereby reducing BH4 levels. D-4F reduced uncoupled eNOS activity by increasing BH4 levels through GCH-1 expression and decreasing eNOS phosphorylation and eNOS-HSP90 association. Our findings elucidate a novel mechanism by which hypercholesterolemia induces atherosclerosis and D-4F inhibits it, providing a potential therapeutic approach.

HSP60 knockdown exerts differential response in endothelial cells and monocyte derived macrophages during atherogenic transformation

Ectopic expression of HSP60 in vascular cells is known to activate auto-immune response that is critical to atherogenic initiation. However, the pathogenic relevance of the aberrant HSP60 upregulation in intracellular signaling pathways associated with atherogenic consequences in vascular cells remains unclear. The aim of the present study was to determine the role of endogenous HSP60 in atherogenic transformation of endothelial cells and macrophages. After generating primary evidence of oxidized low density lipoprotein (OxLDL) induced HSP60 upregulation in human umbilical vein endothelial cells (HUVEC), its physiological relevance in high fat high fructose (HFHF) induced early atherogenic remodelling was investigated in C57BL/6J mice. Prominent HSP60 expression was recorded in tunica intima and media of thoracic aorta that showed hypertrophy, lumen dilation, elastin fragmentation and collagen deposition. Further, HSP60 overexpression was found to be prerequisite for its surface localization and secretion in HUVEC. eNOS downregulation and MCP-1, VCAM-1 and ICAM-1 upregulation with subsequent macrophage accumulation provided compelling evidences on HFHF induced endothelial dysfunction and activation that were also observed in OxLDL treated- and HSP60 overexpressing-HUVEC. OxLDL induced concomitant reduction in NO production and monocyte adhesion were prevented by HSP60 knockdown, implying towards HSP60 mediated possible regulation of the said genes. OxLDL induced HSP60 upregulation and secretion was also recorded in THP-1 derived macrophages (TDMs). HSP60 knockdown in TDMs accounted for higher OxLDL accumulation that correlated with altered scavenger receptors (SR-A1, CD36 and SR-B1) expression further culminating in M1 polarization. Collectively, the results highlight HSP60 upregulation as a critical vascular alteration that exerts differential regulatory role in atherogenic transformation of endothelial cells and macrophages.

Immunohistochemical detection of IL-17 and IL-23 improves the identification of patients with a possible diagnosis of Sjogren's syndrome

OBJECTIVES

The diagnosis of primary Sjogren's syndrome (pSS) continues to be difficult and several patients keep symptomatic for years with different diagnoses before confirmation of pSS. Since the IL-23-IL-17 axis is involved in the etiopathogenesis of pSS we evaluated by immunohistochemistry and morphometric methods the presence of IL-17 as well as IL-23 within minor salivary glands (MSG) obtained from patients with uncertain diagnosis of pSS.

MATERIALS AND METHODS

42 patients, with symptoms attributable to pSS, and 8 patients used as a control, were enrolled for the study. Autoantibody detection, histological analysis for the presence of Germinal Centers (GC+), immunohistochemistry to detect IL-23 and IL-17 were performed.

RESULTS

The detection of GC + anti-SSA and anti-SSB antibody in parallel with the detection of IL-17 and IL-23, displays only a diagnostic reinforcement value. Instead, the detection of a positive reaction for both IL-17 and IL-23 without GC + or autoantibody within minor salivary glands, as detected in 36 % of patients with uncertain diagnosis, may be hold as a sensitive and specific marker to identify those patients who are likely to evolve into pSS.

CONCLUSION

we suggest to use the IL-17/ IL-23 immunohistochemical detection to improve the identification of patients with a possible diagnosis in all cases which do not fully meet the American-European criteria for pSS, in particular when the GC + are not present at histopathological analysis and anti-SSA and anti-SSB antibody are undetectable in the serum.

Antibodies to Heat Shock Proteins 90α and 90β in Psoriasis

One of many hypotheses of psoriasis pathogenesis supposes an overexpression of heat shock proteins (Hsps) in different skin layers and systemic immunologic response to them. Hsp90 is one of the most abundant chaperone in eukaryotic cells. The number of studies concerning the role of Hsp90 and anti-Hsp90 antibodies in etiopathogenesis of various diseases is also constantly expanding. Still, there are not many reports concerning potential involvement of this Hsp family or anti-Hsp90 immunization in pathomechanism of psoriasis. The aim of the study was the estimation of anti-Hsp90α and anti-Hsp90β IgG antibodies in the sera of the psoriatic patients at different phases of disease activity in comparison to the sera of healthy individuals. The study material consisted of sera from psoriasis patients (n = 80) in active phase and in the remission phase and healthy individuals (n = 80). Concentrations of anti-Hsp90α and anti-Hsp90β IgG antibodies were determined using ELISA technique. In the patients with psoriasis (both in the active phase of the disease and in the remission phase) concentrations of anti-Hsp90α antibodies were significantly higher than in healthy individuals and they correlated positively with psoriasis area severity index values. The mean concentrations of anti-Hsp90β antibodies in the psoriatic patients and healthy controls were comparable. The obtained results indicate an existence of increased immunological response to Hsp90α in psoriasis. It may suggest the role of the extracellular form of this chaperone and/or anti-Hsp90α antibodies in etiopathogenesis of this dermatosis. The inhibition of Hsp90α may represent a novel therapeutic approach to treat psoriasis.

Molecular signatures of atherosclerotic plaques: An up-dated panel of protein related markers

Atherosclerosis remains the leading cause of ischemic syndromes such as myocardial infarction or brain stroke, mainly promoted by plaque rupture and subsequent arterial blockade. Identification of vulnerable or high-risk plaques constitutes a major challenge, being necessary to identify patients at risk of occlusive events in order to provide them with appropriate therapies. Clinical imaging tools have allowed the identification of certain structural indicators of prone-rupture plaques, including a necrotic lipidic core, intimal and adventitial inflammation, extracellular matrix dysregulation, and smooth muscle cell depletion and micro-calcification. Additionally, alternative approaches focused on identifying molecular biomarkers of atherosclerosis have also been applied. Among them, proteomics has provided numerous protein markers currently investigated in clinical practice. In this regard, it is quite uncertain that a single molecule can describe plaque rupture, due to the complexity of the process itself. Therefore, it should be more accurate to consider a set of markers to define plaques at risk. Herein, we propose a selection of 76 proteins, from classical inflammatory to recently related markers, all of them identified in at least two proteomic studies analyzing unstable atherosclerotic plaques. Such panel could be used as a prognostic signature of plaque instability.

Heat shock protein 90 is downregulated in calcific aortic valve disease

Background

Calcific aortic valve disease (CAVD) is an atheroinflammatory process; finally it leads to progressive calcification of the valve. There is no effective pharmacological treatment for CAVD and many of the underlying molecular mechanisms remain unknown. We conducted a proteomic study to reveal novel factors associated with CAVD.

Methods

We compared aortic valves from patients undergoing valvular replacement surgery due to non-calcified aortic insufficiency (control group, n = 5) to a stenotic group (n = 7) using two-dimensional difference gel electrophoresis (2D-DIGE). Protein spots were identified with mass spectrometry. Western blot and immunohistochemistry were used to validate the results in a separate patient cohort and Ingenuity Pathway Analysis (IPA) was exploited to predict the regulatory network of CAVD.

Results

We detected an upregulation of complement 9 (C9), serum amyloid P-component (APCS) and transgelin as well as downregulation of heat shock protein (HSP90), protein disulfide isomerase A3 (PDIA3), annexin A2 (ANXA2) and galectin-1 in patients with aortic valve stenosis. The decreased protein expression of HSP90 was confirmed with Western blot.

Conclusions

We describe here a novel data set of proteomic changes associated with CAVD, including downregulation of the pro-inflammatory cytosolic protein, HSP90.

Roles of Extracellular HSPs as Biomarkers in Immune Surveillance and Immune Evasion

Extracellular heat shock proteins (ex-HSPs) have been found in exosomes, oncosomes, membrane surfaces, as well as free HSP in cancer and various pathological conditions, also known as alarmins. Such ex-HSPs include HSP90 (α, β, Gp96, Trap1), HSP70, and large and small HSPs. Production of HSPs is coordinately induced by heat shock factor 1 (HSF1) and hypoxia-inducible factor 1 (HIF-1), while matrix metalloproteinase 3 (MMP-3) and heterochromatin protein 1 are novel inducers of HSPs. Oncosomes released by tumor cells are a major aspect of the resistance-associated secretory phenotype (RASP) by which immune evasion can be established. The concepts of RASP are: (i) releases of ex-HSP and HSP-rich oncosomes are essential in RASP, by which molecular co-transfer of HSPs with oncogenic factors to recipient cells can promote cancer progression and resistance against stresses such as hypoxia, radiation, drugs, and immune systems; (ii) RASP of tumor cells can eject anticancer drugs, targeted therapeutics, and immune checkpoint inhibitors with oncosomes; (iii) cytotoxic lipids can be also released from tumor cells as RASP. ex-HSP and membrane-surface HSP (mHSP) play immunostimulatory roles recognized by CD91+ scavenger receptor expressed by endothelial cells-1 (SREC-1)+ Toll-like receptors (TLRs)+ antigen-presenting cells, leading to antigen cross-presentation and T cell cross-priming, as well as by CD94+ natural killer cells, leading to tumor cytolysis. On the other hand, ex-HSP/CD91 signaling in cancer cells promotes cancer progression. HSPs in body fluids are potential biomarkers detectable by liquid biopsies in cancers and tissue-damaged diseases. HSP-based vaccines, inhibitors, and RNAi therapeutics are also reviewed.

The HSP90 Family: Structure, Regulation, Function, and Implications in Health and Disease

The mammalian HSP90 family of proteins is a cluster of highly conserved molecules that are involved in myriad cellular processes. Their distribution in various cellular compartments underlines their essential roles in cellular homeostasis. HSP90 and its co-chaperones orchestrate crucial physiological processes such as cell survival, cell cycle control, hormone signaling, and apoptosis. Conversely, HSP90, and its secreted forms, contribute to the development and progress of serious pathologies, including cancer and neurodegenerative diseases. Therefore, targeting HSP90 is an attractive strategy for the treatment of neoplasms and other diseases. This manuscript will review the general structure, regulation and function of HSP90 family and their potential role in pathophysiology.

Oxidative Stress Induces HSP90 Upregulation on the Surface of Primary Human Endothelial Cells: Role of the Antioxidant 7,8-Dihydroxy-4-methylcoumarin in Preventing HSP90 Exposure to the Immune System

We have previously demonstrated that human heat shock protein 90 (HSP90), an intracellular self protein, is the target of cellular and humoral autoimmune responses in patients with carotid atherosclerosis. In this study, we evaluated in vitro whether oxidative stress, a feature of atherosclerotic plaque, alters HSP90 expression in endothelial cells, thus inducing surface localization of this molecule and whether the antioxidant compound 7,8-dihydroxy-4-methylcoumarin (7,8-DHMC) is able to prevent oxidative stress-induced alterations of HSP90 localization. By the use of flow cytometry, immunofluorescence, enzyme-linked immunosorbent assay, and semiquantitative reverse-transcription polymerase chain reaction, we demonstrated that exposure of human umbilical vein endothelial cells (HUVEC) to the prooxidant compound H₂O₂ upregulated HSP90 surface expression and reduced its secretion without altering HSP90 gene expression and intracytoplasmic protein levels. Pretreatment of HUVEC with 7,8-DHMC prevented H₂O₂-induced alterations of HSP90 cellular distribution and secretion. Our results suggest that the strong oxidative conditions of atherosclerotic plaques promote the upregulation of HSP90 surface expression on endothelial cells, thus rendering the protein a possible target of autoimmune reactions. The antioxidant 7,8-DHMC, by preventing oxidative-stress-triggered HSP90 surface upregulation, may be useful to counteract possible autoreactive reactions to HSP90.

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.

Systematic analysis of the molecular mechanism underlying atherosclerosis using a text mining approach

Background

Atherosclerosis is one of the common health threats all over the world. It is a complex heritable disease that affects arterial blood vessels. Chronic inflammatory response plays an important role in atherogenesis. There has been little success in fully identifying functionally important genes in the pathogenesis of atherosclerosis.

Results

In the present study, we performed a systematic analysis of atherosclerosis-related genes using text mining. We identified a total of 1312 genes. Gene ontology (GO) analysis revealed that a total of 35 terms exhibited significance (p < 0.05) as overrepresented terms, indicating that atherosclerosis invokes many genes with a wide range of different functions. Pathway analysis demonstrated that the most highly enriched pathway is the Toll-like receptor signaling pathway. Finally, through gene network analysis, we prioritized 48 genes using the hub gene method.

Conclusions

Our study provides a valuable resource for the in-depth understanding of the mechanism underlying atherosclerosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s40246-016-0075-1) contains supplementary material, which is available to authorized users.

Increased expression of phosphorylated forms of heat-shock protein-27 and p38MAPK in macrophage-rich regions of fibro-fatty atherosclerotic lesions in the rabbit

We aimed to assess the expression and distribution of Hsp27, pHsp27 (Ser82), p38MAPK and p-p38MAPK in fibro-fatty atherosclerotic lesions and the myocardium of hypercholesterolaemic rabbits. Male New Zealand white rabbits were fed a high-cholesterol diet for 18 weeks, maintaining serum cholesterol at approximately 20 mmol/l over this period. Aortic arch and myocardial tissues were analysed by Western blot, immunohistochemistry and double immunofluorescence. Plasma Hsp27 levels were measured by ELISA. There was a significant increase in the expression of monomeric and dimeric forms of Hsp27, together with pHsp27 (Ser82), p38MAPK and p-p38MAPK in the fibro-fatty atherosclerotic lesions (P < 0.01; P < 0.05; P < 0.001; and P < 0.001, respectively) and the myocardial tissues (P < 0.001) from the cholesterol-fed rabbits compared with equivalent tissues from controls when the plasma concentration was low. Immunohistochemical analysis of the fibro-fatty lesions showed marked increases in Hsp27 and pHsp27 (Ser82) immunoreactivity. Double immunostaining showed intense expression of pHsp27 and p-p38MAPK in regions that were rich in macrophages, suggesting a close association with these inflammatory cells, whereas, in regions rich in smooth muscle cells, only p-p38MAPK was found to be strongly expressed. An increased expression of pHsp27 (Ser82) was spatially associated with increased p-p38MAPK within fibro-fatty atherosclerotic lesions and was colocalized to regions rich in macrophages. The initial increase in plasma Hsp27 levels may reflect the increase in systemic inflammation and oxidative stress in the early phases of disease. The falling concentrations subsequently may be coincident with the development of the advanced atherosclerotic lesions.

Mucosal Administration of Collagen V Ameliorates the Atherosclerotic Plaque Burden by Inducing Interleukin 35-dependent Tolerance

We have shown previously that collagen V (col(V)) autoimmunity is a consistent feature of atherosclerosis in human coronary artery disease and in the Apoe(-/-) mouse model. We have also shown sensitization of Apoe(-/-) mice with col(V) to markedly increase the atherosclerotic burden, providing evidence of a causative role for col(V) autoimmunity in atherosclerotic pathogenesis. Here we sought to determine whether induction of immune tolerance to col(V) might ameliorate atherosclerosis, providing further evidence for a causal role for col(V) autoimmunity in atherogenesis and providing insights into the potential for immunomodulatory therapeutic interventions. Mucosal inoculation successfully induced immune tolerance to col(V) with an accompanying reduction in plaque burden in Ldlr(-/-) mice on a high-cholesterol diet. The results therefore demonstrate that inoculation with col(V) can successfully ameliorate the atherosclerotic burden, suggesting novel approaches for therapeutic interventions. Surprisingly, tolerance and reduced atherosclerotic burden were both dependent on the recently described IL-35 and not on IL-10, the immunosuppressive cytokine usually studied in the context of induced tolerance and amelioration of atherosclerotic symptoms. In addition to the above, using recombinant protein fragments, we were able to localize two epitopes of the α1(V) chain involved in col(V) autoimmunity in atherosclerotic Ldlr(-/-) mice, suggesting future courses of experimentation for the characterization of such epitopes.

Targeting HSP90 Ameliorates Nephropathy and Atherosclerosis Through Suppression of NF-κB and STAT Signaling Pathways in Diabetic Mice

Heat shock proteins (HSPs) are induced by cellular stress and function as molecular chaperones that regulate protein folding. Diabetes impairs the function/expression of many HSPs, including HSP70 and HSP90, key regulators of pathological mechanisms involved in diabetes complications. Therefore, we investigated whether pharmacological HSP90 inhibition ameliorates diabetes-associated renal damage and atheroprogression in a mouse model of combined hyperglycemia and hyperlipidemia (streptozotocin-induced diabetic apolipoprotein E-deficient mouse). Treatment of diabetic mice with 17-dimethylaminoethylamino-17-demethoxygeldanamycin (DMAG, 2 and 4 mg/kg, 10 weeks) improved renal function, as evidenced by dose-dependent decreases in albuminuria, renal lesions (mesangial expansion, leukocyte infiltration, and fibrosis), and expression of proinflammatory and profibrotic genes. Furthermore, DMAG significantly reduced atherosclerotic lesions and induced a more stable plaque phenotype, characterized by lower content of lipids, leukocytes, and inflammatory markers, and increased collagen and smooth muscle cell content. Mechanistically, the renoprotective and antiatherosclerotic effects of DMAG are mediated by the induction of protective HSP70 along with inactivation of nuclear factor-κB (NF-κB) and signal transducers and activators of transcription (STAT) and target gene expression, both in diabetic mice and in cultured cells under hyperglycemic and proinflammatory conditions. In conclusion, HSP90 inhibition by DMAG restrains the progression of renal and vascular damage in experimental diabetes, with potential implications for the prevention of diabetes complications.

Purinergic signaling in atherosclerosis

Cell surface expression of specific receptors and ecto-nucleotidases makes extracellular nucleotides such as ATP, ADP, UTP, and adenosine suitable as signaling molecules for physiological and pathological events, including tissue stress and damage. Recent data have revealed the participation of purinergic signaling in atherosclerosis, depicting a scenario in which, in addition to some exceptions reflecting dual effects of individual receptor subtypes, adenosine and most P1 receptors, as well as ecto-nucleotidases, show a protective, anti-atherosclerotic function. By contrast, P2 receptors promote atherosclerosis. In consideration of these findings, modulation of purinergic signaling would represent an innovative and valuable tool to counteract atherosclerosis. We summarize recent developments on the participation of the purinergic network in atheroma formation and evolution.

Heat shock proteins and cardiovascular disease

Atherosclerosis is the leading global cause of mortality, morbidity, and disability. Heat shock proteins (HSPs) are a highly conserved family of proteins with diverse functions expressed by all cells exposed to environmental stress. Studies have reported that several HSPs may be potential risk markers of atherosclerosis and related cardiovascular diseases, or may be directly involved in the atherogenic process itself. HSPs are expressed by cells in atherosclerotic plaque and anti-HSP has been reported to be increased in patients with vascular disease. Autoimmune responses may be generated against antigens present within the atherosclerotic plaque, including HSP and may lead to a cycle of ongoing vascular injury. It has been suggested that by inducing a state of tolerance to these antigens, the atherogenic process may be limited and thus provide a potential therapeutic approach. It has been suggested that anti-HSPs are independent predictors of risk of vascular disease. In this review, we summarize the current understanding of HSP in cardiovascular disease and highlight their potential role as diagnostic agents and therapeutic targets.

The role of heat shock proteins in atherosclerosis

Atherosclerosis is a chronic, multifactorial disease that starts in youth, manifests clinically later in life, and can lead to myocardial infarction, stroke, claudication, and death. Although inflammatory processes have long been known to be involved in atherogenesis, interest in this subject has grown in the past 30-40 years. Animal experiments and human analyses of early atherosclerotic lesions have shown that the first pathogenic event in atherogenesis is the intimal infiltration of T cells at arterial branching points. These T cells recognize heat shock protein (HSP)60, which is expressed together with adhesion molecules by endothelial cells in response to classic risk factors for atherosclerosis. Although these HSP60-reactive T cells initiate atherosclerosis, antibodies to HSP60 accelerate and perpetuate the disease. All healthy humans develop cellular and humoral immunity against microbial HSP60 by infection or vaccination. Given that prokaryotic (bacterial) and eukaryotic (for instance, human) HSP60 display substantial sequence homology, atherosclerosis might be the price we pay for this protective immunity, if risk factors stress the vascular endothelial cells beyond physiological conditions.

The role of heat shock protein 90 in migration and proliferation of vascular smooth muscle cells in the development of atherosclerosis

The molecular chaperone heat shock protein 90 (HSP90) is overexpressed in plaques of atherosclerosis patients, and is associated with plaque instability. However, the role of HSP90 in atherosclerosis remains unclear. The present study investigated the effects of HSP90 inhibition on migration and proliferation of vascular smooth muscle cells (VSMCs) and involvement in atherosclerosis. To examine the role of HSP90 in VSMC migration, VSMCs were treated with the specific HSP90 inhibitors, 17-N-allylamino-17-demethoxygeldanamycin (17-AAG) and STA-9090. Results of a chemotaxis assay showed that the HSP90 inhibitors suppress migration of VSMCs. HSP90 inhibition also prevented invasion and sprout formation of VSMCs via inhibition of matrix metalloproteinase-2 proteolytic activity. Results of a flow cytometric analysis showed that HSP90 inhibition induces cell cycle arrest via regulation of cyclin D3, PCNA and pRb. To investigate the role of HSP90 in the development of atherosclerosis, low-density lipoprotein receptor (LDLR) deficient mice were fed with a high cholesterol diet for 4weeks and treated with 17-AAG for 8weeks. HSP90 inhibition suppressed migration of VSMCs into atherosclerotic plaque lesions in high cholesterol diet-stimulated LDLR(-/-) mice. Inhibition of HSP90 attenuates formation of atherosclerotic plaques via suppression of VSMC migration and proliferation, indicating that HSP90 inhibitors can be used as therapeutic agents for atherosclerosis and in stent restenosis.

Differential humoral responses against heat-shock proteins after autologous stem cell transplantation in multiple myeloma

Heat-shock proteins (HSP) are important molecules in the pathogenesis of multiple myeloma (MM). Their blockages by drugs or cellular immune response have been investigated, and a possible association with the presence of oligoclonal bands (OB) has been postulated in patients with MM after allogenic stem cell transplantation. The aim of the present study was to ascertain the serum antibody levels against three HSP (60, 70 and 90) by ELISA in patients with MM in complete remission after autologous stem cell transplantation (ASCT), with or without OB, and compare them with those patients with stable gammopathy of undetermined significance (MGUS) and healthy controls. Our results in samples after ASCT showed no differential levels of anti-HSP according to the presence or absence of the oligoclonal response. However, higher levels of anti-HSP90 were found in patients with stable MGUS in comparison with MM patients (p = 0.004). In the same line, a longer progression-free survival was observed in those patients who presented higher anti-HSP90 levels after ASCT (p = 0.042). These results suggest, for first time, the potential of anti-HSP90 humoral immune response for long-term control of malignant plasma cell disorders.

Aberrant expression and secretion of heat shock protein 90 in patients with bullous pemphigoid

The cell stress chaperone heat shock protein 90 (Hsp90) has been implicated in inflammatory responses and its inhibition has proven successful in different mouse models of autoimmune diseases, including epidermolysis bullosa acquisita. Here, we investigated expression levels and secretory responses of Hsp90 in patients with bullous pemphigoid (BP), the most common subepidermal autoimmune blistering skin disease. In comparison to healthy controls, the following observations were made: (i) Hsp90 was highly expressed in the skin of BP patients, whereas its serum levels were decreased and inversely associated with IgG autoantibody levels against the NC16A immunodominant region of the BP180 autoantigen, (ii) in contrast, neither aberrant levels of circulating Hsp90 nor any correlation of this protein with serum autoantibodies was found in a control cohort of autoimmune bullous disease patients with pemphigus vulgaris, (iii) Hsp90 was highly expressed in and restrictedly released from peripheral blood mononuclear cells of BP patients, and (iv) Hsp90 was potently induced in and restrictedly secreted from human keratinocyte (HaCaT) cells by BP serum and isolated anti-BP180 NC16A IgG autoantibodies, respectively. Our results reveal an upregulated Hsp90 expression at the site of inflammation and an autoantibody-mediated dysregulation of the intracellular and extracellular distribution of this chaperone in BP patients. These findings suggest that Hsp90 may play a pathophysiological role and represent a novel potential treatment target in BP.

Stress and obesity as risk factors in cardiovascular diseases: a neuroimmune perspective

Obesity is now growing at an alarming rate reaching epidemic proportions worldwide thus increasing morbidity and mortality rates for chronic disease. But although we have ample information on the complications associated with obesity, precisely what causes obesity remains poorly understood. Some evidence attributes a major role to a low-grade chronic inflammatory state (neurogenic inflammation) induced in obesity by inflammatory mediators produced and secreted within the expanded activated adipocyte pool. Adipose tissue is an endocrine organ that secretes numerous adipose tissue-specific or enriched hormones, known as adipokines, cytokine-like molecules thought to play a pathogenic role in cardiovascular diseases. The imbalance between increased inflammatory stimuli and decreased anti-inflammatory mechanisms may depend on chronic stress. Hence the positive correlation found between stress, obesity and cardiovascular diseases. The chronic inflammatory state associated with insulin resistance and endothelial dysfunction is highly deleterious for vascular function. This review focuses on the proposed neuroimmunodulatory mechanisms linking chronic (psychological) stress, obesity and cardiovascular diseases.

Heat shock proteins: pathogenic role in atherosclerosis and potential therapeutic implications

Heat shock proteins (HSPs) are a highly conserved group of proteins that are constitutively expressed and function as molecular chaperones, aiding in protein folding and preventing the accumulation of misfolded proteins. In the arterial wall, HSPs have a protective role under normal physiologic conditions. In disease states, however, HSPs expressed on the vascular endothelial cell surface can act as targets for detrimental autoimmunity due to their highly conserved sequences. Developing therapeutic strategies for atherosclerosis based on HSPs is challenged by the need to balance such physiologic and pathologic roles of these proteins. This paper summarizes the role of HSPs in normal vascular wall processes as well as in the development and progression of atherosclerosis. The potential implications of HSPs in clinical therapies for atherosclerosis are also discussed.

T lymphocyte autoreactivity in inflammatory mechanisms regulating atherosclerosis

Atherosclerosis has been clearly demonstrated to be a chronic inflammatory disease of the arterial wall. Both cells of the innate and the acquired immune system, particularly monocytes and T lymphocytes, are implicated in the atherogenic process, producing different cytokines with pro- and anti-inflammatory effects. The majority of pathogenic T cells involved in atherosclerosis are of the Th1 profile, that has been correlated positively with coronary artery disease. Many studies conducted to evaluate the molecular factors responsible for the activation of T cells have demonstrated that the main antigenic targets in atherosclerosis are modified endogenous structures. These self-molecules activate autoimmune reactions mainly characterized by the production of Th1 cytokines, thus sustaining the inflammatory mechanisms involved in endothelial dysfunction and plaque development. In this paper we will summarize the different T-cell subsets involved in atherosclerosis and the best characterized autoantigens involved in cardiovascular inflammation.

Neuroimmunology of the atherosclerotic plaque: a morphological approach

Atherosclerosis is a chronic inflammatory process, lasting for several decades until the onset of its clinical manifestations. The progression of the atherosclerotic lesion to a stable fibrotic plaque, narrowing the vascular lumen, or to a vulnerable plaque leading to main vascular complications, is associated to the involvement of several cell subpopulations of the innate as well as of the adaptive immunity, and to the release of chemokines and pro-inflammatory cytokines. Emerging evidence outlines that the cardiovascular risk is dependent on stress-mediators influencing cell migration and vascular remodeling. The view that atherosclerosis is initiated by monocytes and lymphocytes adhering to dysfunctional endothelial cells is substantiated by experimental and clinical observations. Macrophages, dendritic cells, T and B lymphocytes, granulocytes accumulating into the subendothelial space secrete and are stimulated by soluble factors, including peptides, proteases and cytokines acting synergistically. The final step of the disease, leading to plaque destabilization and rupture, is induced by the release, at the level of the fibrous cap, of metalloproteinases and elastases by the activated leukocytes which accumulate locally. Recruitment of specific cell subpopulations as well as the progression of atherosclerotic lesions towards a stable or an unstable phenotype, are related to the unbalance between pro-atherogenic and anti-atherogenic factors. In this connection stress hormones deserve particular attention, since their role in vascular remodeling, via vascular smooth cell proliferation, as well as in neoangiogenesis, via stimulation of endothelial cell proliferation and migration, has been already established.

Cellular and molecular players in the atherosclerotic plaque progression

Atherosclerosis initiation and progression is controlled by inflammatory molecular and cellular mediators. Cells of innate immunity, stimulated by various endogenous molecules that have undergone a transformation following an oxidative stress or nonenzymatic glycation processes, activate cells of the adaptive immunity, found at the borders of atheromas. In this way, an immune response against endogenous modified antigens takes place and gives rise to chronic low-level inflammation leading to the slow development of complex atherosclerotic plaques. These lesions will occasionally ulcerate, thus ending with fatal clinical events. Plaque macrophages represent the majority of leukocytes in the atherosclerotic lesions, and their secretory activity, including proinflammatory cytokines and matrix-degrading proteases, may be related to the fragilization of the fibrous cap and then to the rupture of the plaque. A considerable amount of work is currently focused on the identification of locally released proinflammatory factors that influence the evolution of the plaque to an unstable phenotype. A better understanding of these molecular processes may contribute to new treatment strategies. Mediators released by the immune system and associated with the development of carotid atherosclerosis are discussed.

Opposing actions of heat shock protein 90 and 70 regulate nicotinamide adenine dinucleotide phosphate oxidase stability and reactive oxygen species production

OBJECTIVE

Excessive reactive oxygen species contribute to vascular dysfunction. We have previously shown that heat shock protein (Hsp90) inhibitors potently suppress Nox 1 to 3 and 5, and the goals of this study were to identify how molecular chaperones regulate Nox function.

METHODS AND RESULTS

In vitro, protein expression of Nox 1 to 2, 5 was decreased by Hsp90 inhibitors in multiple cell types (human pulmonary artery endothelial cells, neutrophils, macrophages, and human saphenous vein). In mice treated with Hsp90 inhibitors, Nox1 expression was reduced in lung along with reduced reactive oxygen species from leukocytes. Elevated reactive oxygen species production in obese (db/db) aorta was suppressed by Hsp90 inhibition. Hsp90 inhibitors did not alter Nox5 micro RNA levels, and proteasome inhibition prevented Nox2 and 5 protein degradation and increased ubiquitin incorporation. Inhibition of Hsp90 upregulated the expression of Hsp70 and Hsp70-bound Nox2, 5 and promoted degradation. Silencing Hsp70 prevented Hsp90 inhibitor-mediated degradation of Nox5. The Hsp70-regulated ubiquitin ligase, carboxyl terminus of Hsp70-interacting protein (CHIP), also bound Nox5 and promoted increased Nox5 ubiquitination and degradation. The chaperone binding and ubiquitination domains of CHIP were required, and the silencing of CHIP blunted Hsp90 inhibitor-mediated degradation of Nox2 and 5.

CONCLUSIONS

We conclude that Hsp90 binds to and regulates Nox protein stability. These actions are opposed by Hsp70 and CHIP, which promote the ubiquitination and degradation of Nox proteins and reduce reactive oxygen species production.

Proteotoxic stress and circulating cell stress proteins in the cardiovascular diseases

The cardiovasculature is one of the major body systems and probably the one most exposed to stress. There is clear evidence that increasing levels of cell stress proteins within the heart is cardioprotective. In addition, there is rapidly emerging evidence that secreted cell stress proteins play a role in the function of the cardiovascular tissues. Those secreted proteins have three potential functions: (1) as normal homeostatic cardiovascular signals (e.g. protein disulphide isomerase); (2) as anti-inflammatory molecules, which are able to inhibit cardiovascular pathology (e.g. Hsp27); and (iii) as pro-inflammatory signals that can induce and promote cardiovascular pathology (e.g. Hsp60). As all of these various proteins may be released-at different rates-and in different cardiovascular diseases-we need to consider the cohort of potential secreted cell stress proteins as a dynamic system (network) that can aid and/or damage the equally dynamic cardiovascular system.

Matrix metalloprotein-9 activation under cell-to-cell interaction between endothelial cells and monocytes: possible role of hypoxia and tumor necrosis factor-α

Matrix metalloproteinase (MMP)-9 plays an important role in cardiovascular events. However, the mechanisms underlying in vivo activation of MMP-9 are largely unknown. We investigated the secretion and activation of MMP-9 under a cell-to-cell interaction, and the effects of hypoxia and cytokine. Human umbilical vein endothelial cell (HUVEC) and THP-1 (human monocyte cell line) were cultured individually, or cocultured under normoxic and hypoxic conditions. In a coculture of HUVEC and THP-1, proMMP-9 secretion was increased twofold compared with individual culture of HUVEC and THP-1, whereas MMP-2 secretion was unchanged. The increase in proMMP-9 secretion was suppressed by antiadhesion molecule antibodies and mitogen-activated protein kinase inhibitors, PD98059 (MAPK/ERK kinase1 inhibitor) and SP600125 (Jun N-terminal kinase inhibitor). ProMMP-9 secretion was increased by tumor necrosis factor (TNF)-α at 50 ng/ml (P < 0.05) but was not activated under normoxic (20%) conditions. ProMMP-9 in coculture was activated under hypoxic (<1%) conditions, and was potentiated by TNF-α (both P < 0.05). To further investigate the mechanism of hypoxia-induced MMP-9 activation, heat shock protein (Hsp)90, which was suggested to be related to MMP-9 activation, was measured by Western blot analysis. The ratio of Hsp90 to glyceraldehyde-3-phosphate dehydrogenase was increased in hypoxic (<1%) coculture conditions with TNF-α (P < 0.05). Treatment with geldanamycin and 17-DMAG (Hsp90 inhibitor) suppressed the active form of MMP-9. Cell-to-cell interaction between endothelial cells and monocytes promotes proMMP-9 synthesis and secretion. Hypoxia and inflammation are suggested to play an important role in activating proMMP-9, presumably via Hsp90.

Redox imbalance of red blood cells impacts T lymphocyte homeostasis: implication in carotid atherosclerosis

Oxidative stress and immune/inflammatory responses are key pathogenetic factors of atherosclerotic disease. In this contest, mechanisms that regulate survival and death of immune cells may be relevant. Previous studies have demonstrated that red blood cells (RBCs) are physiologically able to inhibit apoptosis and to promote proliferation of activated T lymphocytes from healthy subjects. The aim of the present study was to evaluate whether RBCs from patients with carotid atherosclerosis maintain their property to modulate T cell homeostasis. Peripheral blood lymphocytes (PBLs) obtained from healthy subjects were activated in vitro by phytohemagglutinin in the presence/absence of RBCs from patients with carotid atherosclerosis or of in vitro oxidised RBCs from healthy subjects. Levels of reactive oxygen species (ROS) and aging markers of RBCs as well as susceptibility to apoptosis of PBLs were evaluated by flow cytometry. PBL proliferation was evaluated by 3H-methyl-thymidine incorporation assay whereas secretion of cytokines, analysed in view of their key role in T cell function, was assessed by ELISA. Levels of ROS and phosphatidyl-serine externalisation, a sign of RBC aging, resulted significantly higher in RBCs from patients than in those from healthy subjects, whereas surface glycophorin A expression and reduced glutathione content did the opposite. Unlike RBCs obtained from healthy subjects, RBCs from patients and in vitro oxidised RBCs did not protect activated T lymphocytes from apoptosis. Hence, RBCs from patients with carotid atherosclerosis, probably due to their oxidative imbalance, impact T cell integrity and function. Our results suggest a new regulatory role for RBCs in atherosclerosis.

Oxidative stress in cardiovascular inflammation: its involvement in autoimmune responses

Recently, it has become clear that atherosclerosis is a chronic inflammatory disease in which inflammation and immune responses play a key role. Accelerated atherosclerosis has been reported in patients with autoimmune diseases, suggesting an involvement of autoimmune mechanisms in atherogenesis. Different self-antigens or modified self-molecules have been identified as target of humoral and cellular immune responses in patients with atherosclerotic disease. Oxidative stress, increasingly reported in these patients, is the major event causing structural modification of proteins with consequent appearance of neoepitopes. Self-molecules modified by oxidative events can become targets of autoimmune reactions, thus sustaining the inflammatory mechanisms involved in endothelial dysfunction and plaque development. In this paper, we will summarize the best characterized autoantigens in atherosclerosis and their possible role in cardiovascular inflammation.

Proteomic characterization of thymocyte-derived microvesicles and apoptotic bodies in BALB/c mice

Several studies have characterized exosomes derived from different cell sources. In this work we set the goal of proteomic characterization of two less studied populations of membrane vesicles, microvesicles (100-800 nm) and apoptotic bodies (> 800 nm) released by thymus cells of BALB/c mice. The vesicles were isolated by the combination of differential centrifugation and gravity driven multistep filtration of the supernatant of thymus cell cultures. The size distribution of vesicle preparations was determined by transmission electron microscopy. Proteins were released from the vesicles, digested in solution, and analyzed using nano-HPLC/MS(MS). Ingenuity pathway analysis was used to identify functions related to membrane vesicle proteins. In apoptotic bodies and microvesicles we have identified 142 and 195 proteins, respectively. A striking overlap was detected between the proteomic compositions of the two subcellular structures as 108 proteins were detected in both preparations. Identified proteins included autoantigens implicated in human autoimmune diseases, key regulators of T-cell activation, molecules involved in known immune functions or in leukocyte rolling and transendothelial transmigration. The presence and abundance of proteins with high immunological relevance within thymocyte-derived apoptotic bodies and microvesicles raise the possibility that these subcellular structures may substantially modulate T-cell maturation processes within the thymus.

Heat shock proteins in oncology: diagnostic biomarkers or therapeutic targets?

Heat shock proteins (HSP) are a family of proteins induced in cells exposed to different insults. This induction of HSPs allows cells to survive stress conditions. Mammalian HSPs have been classified into six families according to their molecular size: HSP100, HSP90, HSP70, HSP60, HSP40 and small HSPs (15 to 30kDa) including HSP27. These proteins act as molecular chaperones either helping in the refolding of misfolded proteins or assisting in their elimination if they become irreversibly damaged. In recent years, proteomic studies have characterized several different HSPs in various tumor types which may be putative clinical biomarkers or molecular targets for cancer therapy. This has led to the development of a series of molecules capable of inhibiting HSPs. Numerous studies speculated that over-expression of HSP is in part responsible for resistance to many anti-tumor agents and chemotherapeutics. Hence, from a pharmacological point of view, the co-administration of HSP inhibitors together with other anti-tumor agents is of major importance in overcoming therapeutic resistance. In this review, we provide an overview of the current status of HSPs in autoimmune, cardiovascular, and neurodegenerative diseases with special emphasis on cancer.

Matrix metalloproteinases (MMP-2,9) and their tissue inhibitors (TIMP-1,2) as novel markers of stress response and atherogenesis in children with chronic kidney disease (CKD) on conservative treatment

The system of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) may play a key role in atherogenesis of chronic kidney disease (CKD) patients by its impact on matrix accumulation. Connections with inflammation, stress, or endothelial dysfunction are also probable. However, the data on correlations between these parameters in CKD patients are scarce in adults and absent in children. The aim of our study was to evaluate serum concentrations of MMP-2, MMP-9, TIMP-1, and TIMP-2, as well as their correlations with markers of stress response (Hsp90-α, anti-Hsp60), endothelial dysfunction (sE-selectin), and inflammation (high-sensitivity C-reactive protein) in CKD children treated conservatively. Thirty-seven patients were divided into two groups according to the CKD stage (gr.CKDI, 19 children with CKD stages 2-3; gr.CKDII, 18 subjects with CKD stages 4-5). Twenty-four age-matched healthy subjects served as controls. Serum concentrations of MMP-2, MMP-9, TIMP-1, TIMP-2, Hsp90-α, anti-Hsp60, and sE-selectin were assessed by ELISA. Median values of MMP-2, MMP-9, TIMP-1, and TIMP-2 were significantly higher in all CKD children vs. controls and were increased in patients with CKD stages 4-5 vs. CKD stages 2-3. Hsp90-α, anti-Hsp60, sE-selectin, and glomerular filtration rate predicted the values of MMPs and TIMPs. Chronic kidney disease in children is characterized by MMP/TIMP system dysfunction, aggravated by the progression of renal failure. Correlations between examined parameters, heat shock proteins, and markers of endothelial damage suggest the possibility of MMP/TIMP application as indicators of stress response and atherogenesis in children with CKD on conservative treatment.

Heat shock proteins in chronic kidney disease

Heat shock proteins (HSP) form a heterogenous, evolutionarily conserved group of molecules with high sequence homology. They mainly act as intracellular chaperones, protecting the protein structure and folding under stress conditions. The extracellular HSP, released in the course of damage or necrosis, play a pivotal role in the innate and adaptive immune responses. They also take part in many pathological processes. The aim of this review is to update the recent developments in the field of HSP in chronic kidney disease (CKD), in regard to three different aspects. The first is the assessment of the role of HSP, either positive or deleterious, in the pathogenesis of CKD and the possibilities to influence its progression. The second is the impact of dialysis, being a potentially modifiable stressor, on HSP and the attempt to assess the value of these proteins as the biocompatibility markers. The last area is that of kidney transplantation and the potential role of HSP in the induction of the immune tolerance in kidney recipients.

Heat-shock proteins in cardiovascular disease

Heat-shock proteins (HSPs) belong to a group of highly conserved families of proteins expressed by all cells and organisms and their expression may be constitutive or inducible. They are generally considered as protective molecules against different types of stress and have numerous intracellular functions. Secretion or release of HSPs has also been described, and potential roles for extracellular HSPs reported. HSP expression is modulated by different stimuli involved in all steps of atherogenesis including oxidative stress, proteolytic aggression, or inflammation. Also, antibodies to HSPs may be used to monitor the response to different types of stress able to induce changes in HSP levels. In the present review, we will focus on the potential implication of HSPs in atherogenesis and discuss the limitations to the use of HSPs and anti-HSPs as biomarkers of atherothrombosis. HSPs could also be considered as potential therapeutic targets to reinforce vascular defenses and delay or avoid clinical complications associated with atherothrombosis.

Interleukin-17-dependent autoimmunity to collagen type V in atherosclerosis

RATIONALE

Considerable evidence shows atherosclerosis to be a chronic inflammatory disease in which immunity to self-antigens contributes to disease progression. We recently identified the collagen type V [col(V)] α1(V) chain as a key autoantigen driving the Th17-dependent cellular immunity underlying another chronic inflammatory disease, obliterative bronchiolitis. Because specific induction of α1(V) chains has previously been reported in human atheromas, we postulated involvement of col(V) autoimmunity in atherosclerosis.

OBJECTIVE

To determine whether col(V) autoimmunity may be involved in the pathogenesis of atherosclerosis.

METHODS AND RESULTS

Here, we demonstrate Th17-dependent anti-col(V) immunity to be characteristic of atherosclerosis in human coronary artery disease (CAD) patients and in apolipoprotein E-null (ApoE(-/-)) atherosclerotic mice. Responses were α1(V)-specific in CAD with variable Th1 pathway involvement. In early atherosclerosis in ApoE(-/-) mice, anti-col(V) immunity was tempered by an interleukin (IL)-10-dependent mechanism. In support of a causal role for col(V) autoimmunity in the pathogenesis of atherosclerosis, col(V) sensitization of ApoE(-/-) mice on a regular chow diet overcame IL-10-mediated inhibition of col(V) autoimmunity, leading to increased atherosclerotic burden in these mice and local accumulation of IL-17-producing cells, particularly in the col(V)-rich adventitia subjacent to the atheromas.

CONCLUSIONS

These findings establish col(V) as an autoantigen in human CAD and show col(V) autoimmunity to be a consistent feature in atherosclerosis in humans and mice. Furthermore, data are consistent with a causative role for col(V) in the pathogenesis of atherosclerosis.

The Role of Immune Complexes in Atherogenesis

Atherosclerosis is now recognized as a chronic inflammatory disease and is characterized by features of inflammation at all stages of its development. It also appears to display elements of autoimmunity, and several autoantibodies including those directed against oxidized low-density lipoprotein (ox-LDL) and heat shock proteins (Hsps) have been identified in atherosclerosis. Immune complexes (ICs) may form between these antigens and autoantibodies and via Fc receptor signaling and complement activation may modulate the inflammation in atherosclerosis. Antibody isotype may direct the role that ICs play in atherogenesis, immunoglobulin G (IgG) being potentially pro-atherogenic and immunoglobulin M (IgM) playing a protective role. Therapeutic options targeting complement activation and those which are potentially Fc-receptor mediated have been investigated in animal models, though targeting Fc receptor signaling is an area that needs further investigation.