Association between plasma levels and immunolocalization of cytokines in heart valve lesions: a possible target for treatment?

Overview of multifunctional Tregs in cardiovascular disease: From insights into cellular functions to clinical implications

Regulatory T cells (Tregs) are crucial in regulating T-cell-mediated immune responses. Numerous studies have shown that dysfunction or decreased numbers of Tregs may be involved in inflammatory cardiovascular diseases (CVDs) such as atherosclerosis, hypertension, myocardial infarction, myocarditis, cardiomyopathy, valvular heart diseases, heart failure, and abdominal aortic aneurysm. Tregs can help to ameliorate CVDs by suppressing excessive inflammation through various mechanisms, including inhibition of T cells and B cells, inhibition of macrophage-induced inflammation, inhibition of dendritic cells and foam cell formation, and induction of anti-inflammatory macrophages. Enhancing or restoring the immunosuppressive activity of Tregs may thus serve as a fundamental immunotherapy to treat hypertension and CVDs. However, the precise molecular mechanisms underlying the Tregs-induced protection against hypertension and CVDs remain to be investigated. This review focuses on recent advances in our understanding of Tregs subsets and function in CVDs. In addition, we discuss promising strategies for using Tregs through various pharmacological approaches to treat hypertension and CVDs.

Myeloid CCN3 protects against aortic valve calcification

BACKGROUND

Cellular communication network factor 3 (CCN3) has been implicated in the regulation of osteoblast differentiation. However, it is not known if CCN3 can regulate valvular calcification. While macrophages have been shown to regulate valvular calcification, the molecular and cellular mechanisms of this process remain poorly understood. In the present study, we investigated the role of macrophage-derived CCN3 in the progression of calcific aortic valve disease.

METHODS

Myeloid-specific knockout of CCN3 (Mye-CCN3-KO) and control mice were subjected to a single tail intravenous injection of AAV encoding mutant mPCSK9 (rAAV8/D377Y-mPCSK9) to induce hyperlipidemia. AAV-injected mice were then fed a high fat diet for 40 weeks. At the conclusion of high fat diet feeding, tissues were harvested and subjected to histologic and pathologic analyses. In vitro, bone marrow-derived macrophages (BMDM) were obtained from Mye-CCN3-KO and control mice and the expression of bone morphogenic protein signaling related gene were verified via quantitative real-time PCR and Western blotting. The BMDM conditioned medium was cocultured with human valvular intersititial cells which was artificially induced calcification to test the effect of the conditioned medium via Western blotting and Alizarin red staining.

RESULTS

Echocardiography revealed that both male and female Mye-CCN3-KO mice displayed compromised aortic valvular function accompanied by exacerbated valve thickness and cardiac dysfunction. Histologically, Alizarin-Red staining revealed a marked increase in aortic valve calcification in Mye-CCN3-KO mice when compared to the controls. In vitro, CCN3 deficiency augmented BMP2 production and secretion from bone marrow-derived macrophages. In addition, human valvular interstitial cells cultured with conditioned media from CCN3-deficient BMDMs resulted in exaggerated pro-calcifying gene expression and the consequent calcification.

CONCLUSION

Our data uncovered a novel role of myeloid CCN3 in the regulation of aortic valve calcification. Modulation of BMP2 production and secretion in macrophages might serve as a key mechanism for macrophage-derived CCN3's anti-calcification function in the development of CAVD. Video Abstract.

Innate and adaptive immunity: the understudied driving force of heart valve disease

Calcific aortic valve disease (CAVD), and its clinical manifestation that is calcific aortic valve stenosis, is the leading cause for valve disease within the developed world, with no current pharmacological treatment available to delay or halt its progression. Characterized by progressive fibrotic remodelling and subsequent pathogenic mineralization of the valve leaflets, valve disease affects 2.5% of the western population, thus highlighting the need for urgent intervention. Whilst the pathobiology of valve disease is complex, involving genetic factors, lipid infiltration, and oxidative damage, the immune system is now being accepted to play a crucial role in pathogenesis and disease continuation. No longer considered a passive degenerative disease, CAVD is understood to be an active inflammatory process, involving a multitude of pro-inflammatory mechanisms, with both the adaptive and the innate immune system underpinning these complex mechanisms. Within the valve, 15% of cells evolve from haemopoietic origin, and this number greatly expands following inflammation, as macrophages, T lymphocytes, B lymphocytes, and innate immune cells infiltrate the valve, promoting further inflammation. Whether chronic immune infiltration or pathogenic clonal expansion of immune cells within the valve or a combination of the two is responsible for disease progression, it is clear that greater understanding of the immune systems role in valve disease is required to inform future treatment strategies for control of CAVD development.

Adaptive immune cells in calcific aortic valve disease

Calcific aortic valve disease (CAVD) is highly prevalent and has no pharmaceutical treatment. Surgical replacement of the aortic valve has proved effective in advanced disease but is costly, time limited, and in many cases not optimal for elderly patients. This has driven an increasing interest in noninvasive therapies for patients with CAVD. Adaptive immune cell signaling in the aortic valve has shown potential as a target for such a therapy. Up to 15% of cells in the healthy aortic valve are hematopoietic in origin, and these cells, which include macrophages, T lymphocytes, and B lymphocytes, are increased further in calcified specimens. Additionally, cytokine signaling has been shown to play a causative role in aortic valve calcification both in vitro and in vivo. This review summarizes the physiological presence of hematopoietic cells in the valve, innate and adaptive immune cell infiltration in disease states, and the cytokine signaling pathways that play a significant role in CAVD pathophysiology and may prove to be pharmaceutical targets for this disease in the near future.

Association Between Inflammatory Markers and Myocardial Fibrosis

Inflammation promotes adverse ventricular remodeling. T1 mapping has been used to noninvasively assess interstitial myocardial fibrosis. We examined the association of baseline markers of systemic inflammation with interstitial myocardial fibrosis measured by extracellular volume fraction (ECV) and native T1 mapping at 10-year follow-up in the MESA (Multi-Ethnic Study of Atherosclerosis). Seven hundred seventy-two participants had complete baseline data and underwent cardiac magnetic resonance imaging. All analyses were stratified by sex. Multivariable linear regression models were constructed to assess the associations of baseline CRP (C-reactive protein), IL (interleukin)-6, and fibrinogen with native T1 time and ECV. Longer native T1 times and higher percentages of ECV represent increasing myocardial fibrosis. A 1-SD increment of log-transformed IL-6 levels was associated with 0.4% higher ECV in men (β=0.4; P=0.05). CRP and fibrinogen were not associated to ECV. A 1-SD increment in the log-transformed CRP levels was associated with 4.9 ms higher native T1 (β=4.9; P=0.03). In women, the inflammatory markers did not demonstrate association with native T1 nor ECV. Higher IL-6 and CRP levels are associated with increased interstitial myocardial fibrosis assessed by cardiac magnetic resonance in men. However, no inflammatory markers were associated to myocardial fibrosis in women.

The Role of Toll-Like Receptors and Vitamin D in Cardiovascular Diseases-A Review

Cardiovascular diseases are the leading cause of mortality worldwide. Therefore, a better understanding of their pathomechanisms and the subsequent implementation of optimal prophylactic and therapeutic strategies are of utmost importance. A growing body of evidence states that low-grade inflammation is a common feature for most of the cardiovascular diseases in which the contributing factors are the activation of toll-like receptors (TLRs) and vitamin D deficiency. In this article, available data concerning the association of cardiovascular diseases with TLRs and vitamin D status are reviewed, followed by a discussion of new possible approaches to cardiovascular disease management.

Inflammatory Mediators and Clinical Outcome in Patients With Advanced Heart Failure Receiving Cardiac Resynchronization Therapy

Expression of different cytokines and growth factors after myocardial injury has been associated with fibroplasia and dilatation versus reverse remodeling and myocardial repair. Specifically, the proinflammatory/fibrotic mediators: interleukin (IL)-6, epidermal growth factor, and fibroblast growth factor (FGF)-2 cause fibroplasia, whereas reparative cytokines including: IL-1α, IL-1β, IL-4, and IL-13 can limit fibrosis. In appropriate patients, cardiac resynchronization therapy (CRT) reverses cardiomyopathy and improves outcome. However, a significant proportion will not respond to this therapy. We conducted this study to assess the association of proinflammatory/fibrotic and/or reparative immune response mediators at baseline with outcome after CRT. In the multicenter RISK study, plasma samples were collected prospectively before CRT implantation. Plasma IL-6, epidermal growth factor, FGF-2, IL-1α, IL-1β, IL-4, and IL-13 were evaluated by Luminex technology. The primary outcome was predefined as freedom from heart failure hospitalization or death and a decrease in echocardiographic end-systolic volume of >15% at 12 months. To determine associations with the outcome, multivariate logistic regression models including baseline clinical characteristics and the specific cytokines and growth factors were constructed. On multivariate analysis of 257 patients, detectable reparative cytokine IL-13 was significantly associated with the primary outcome (odds ratio 3.79; 95% CI 2.10 to 6.82, p <0.0001). In contrast, detectable proinflammatory/fibrotic growth factor FGF-2 was negatively associated (odds ratio 0.31; 95% CI, 0.14 to 0.68; p = 0.004). In conclusion, in CRT recipients, baseline levels of inflammatory mediators affecting cardiac fibrosis versus repair were associated with subsequent clinical outcome.

The Role of VEGF in the Diabetic Patients Undergoing Endovascular Therapy of Symptomatic Aortic Valve Stenosis

The aim of this study was to explore changes in plasma vascular endothelial growth factor (VEGF) in aged patients who undergone transcatheter aortic valve implantation or balloon angioplasty for the treatment of aortic stenosis. Plasma VEGF was measured in subjects with diabetes mellitus type 2 (DM) (n=21, age 79.2±1.6 years) and in non-diabetic subjects (non-DM) (n=23, age 84.4±0.7 years), using an ELISA kit. Before the procedure plasma levels of VEGF were significantly lower in DM than in non-DM patients (P<0.05). Plasma VEGF significantly increased in both groups (DM and non-DM) 24 h (387±64 vs. 440±30 pg/ml, P<0.05) and 72 h (323±69 vs. 489±47 pg/ml, P<0.05) after the endovascular procedure. However, the VEGF in DM patients was significantly lower compared to non-DM subjects up to one month after the endovascular procedure (283±47 vs. 386±38 pg/ml, P<0.05). We conclude that increased plasma VEGF in aged patients associates with atherosclerotic aortic valve stenosis. In spite of that plasma VEGF in DM was constantly significantly lower than in non diabetic patients, both before and after the endovascular procedure, possibly reflecting a disturbance of angiogenic/anti-angiogenic balance in diabetes.

Inflammatory cytokines promote mesenchymal transformation in embryonic and adult valve endothelial cells

OBJECTIVE

Inflammatory activation of valve endothelium is an early phase of aortic valve disease pathogenesis, but subsequent mechanisms are poorly understood. Adult valve endothelial cells retain the developmental ability to undergo endothelial-to-mesenchymal transformation (EndMT), but a biological role has not been established. Here, we test whether and how inflammatory cytokines (tumor necrosis factor-α and interleukin-6) regulate EndMT in embryonic and adult valve endothelium.

METHODS AND RESULTS

Using in vitro 3-dimensional collagen gel culture assays with primary cells, we determined that interleukin-6 and tumor necrosis factor-α induce EndMT and cell invasion in dose-dependent manners. Inflammatory-EndMT occurred through an Akt/nuclear factor-κB-dependent pathway in both adult and embryonic stages. In embryonic valves, inflammatory-EndMT required canonical transforming growth factor-β signaling through activin receptor-like kinases 2 and 5 to drive EndMT. In adult valve endothelium, however, inflammatory-induced EndMT still occurred when activin receptor-like kinases 2 and 5 signaling was blocked. Inflammatory receptor gene expression was significantly upregulated in vivo during embryonic valve maturation. Endothelial-derived mesenchymal cells expressing activated nuclear factor-κB were found distal to calcific lesions in diseased human aortic valves.

CONCLUSIONS

Inflammatory cytokine-induced EndMT in valve endothelium is present in both embryonic and adult stages, acting through Akt/nuclear factor-κB, but differently using transforming growth factor-β signaling. Molecular signatures of valve EndMT may be important diagnostic and therapeutic targets in early valve disease.

Does diabetes accelerate the progression of aortic stenosis through enhanced inflammatory response within aortic valves?

Diabetes predisposes to aortic stenosis (AS). We aimed to investigate if diabetes affects the expression of selected coagulation proteins and inflammatory markers in AS valves. Twenty patients with severe AS and concomitant type 2 diabetes mellitus (DM) and 40 well-matched patients without DM scheduled for valve replacement were recruited. Valvular tissue factor (TF), TF pathway inhibitor (TFPI), prothrombin, C-reactive protein (CRP) expression were evaluated by immunostaining and TF, prothrombin, and CRP transcripts were analyzed by real-time PCR. DM patients had elevated plasma CRP (9.2 [0.74–51.9] mg/l vs. 4.7 [0.59–23.14] mg/l, p = 0.009) and TF (293.06 [192.32–386.12] pg/ml vs. 140 [104.17–177.76] pg/ml, p = 0.003) compared to non-DM patients. In DM group, TF−, TFPI−, and prothrombin expression within valves was not related to demographics, body mass index, and concomitant diseases, whereas increased expression related to DM was found for CRP on both protein (2.87 [0.5–9]% vs. 0.94 [0–4]%, p = 0.01) and transcript levels (1.3 ± 0.61 vs. 0.22 ± 0.43, p = 0.009). CRP-positive areas were positively correlated with mRNA TF (r = 0.84, p = 0.036). Diabetes mellitus is associated with enhanced inflammation within AS valves, measured by CRP expression, which may contribute to faster AS progression.

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

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

Aortic stenosis and lipids: does intervention work?

PURPOSE OF REVIEW

Aortic stenosis is a common disorder affecting increasing numbers of elderly patients, which is associated with markedly increased cardiovascular morbidity and mortality. Both histological and epidemiological studies have suggested that the process of valve degeneration may resemble atherosclerosis. This review investigates the potential role of lipid-lowering therapy in its management.

RECENT FINDINGS

The current treatment methods are surgical or endovascular intervention but it has been hoped that antiatherosclerotic therapies might result in a reduction in progression and need for intervention. There have been a number of retrospective studies of lipid-lowering therapy, which suggested that statins might be effective in reducing progression of aortic stenosis. Lately a series of trials of aggressive statin therapy on surrogate markers of progression have shown no benefit from these measures. The controversial Simvastatin-Ezetimibe and Aortic Stenosis (SEAS) endpoint trial did not show any benefit on a combined endpoint of valve-related and ischaemic events but hinted at a reduction in cardiovascular events in this high cardiovascular risk group.

SUMMARY

The data clearly shows statins have little effect in well established stenotic disease with calcification, but their effects earlier in the disease process (aortic valve sclerosis) remain to be determined.

Serum leptin levels in patients undergoing carotid endarterectomy: a pilot study

INTRODUCTION

Elevated serum leptin levels are associated with cardiovascular events. We investigated the role of serum leptin in patients undergoing carotid endarterectomy (CEA).

METHODS

A total of 74 patients (55 men; 38 symptomatic and 36 asymptomatic; mean age 66.9 +/- 8.2 years) undergoing CEA for >70% carotid artery stenosis were enrolled.

RESULTS

Serum leptin levels were lower in symptomatic compared with asymptomatic patients (7.1 +/- 1.3 vs 14.4 +/- 4.7 ng/dL; P < .001). Interleukin-6 (IL-6) levels were higher in symptomatic compared with asymptomatic patients (4.3 +/- 1.7 vs 3.3 +/- 1.1 pg/dL; P = .017). Symptomatic patients had more intense macrophage accumulation (0.7% +/- 0.1% vs 0.3% +/- 0.1%; P < .001). Serum leptin and serum IL-6 levels were independently associated with the presence of symptoms in multivariate analysis.

CONCLUSION

Serum leptin levels were decreased in symptomatic carotid artery disease. This finding requires further investigation in larger studies.

Short-term induction of thrombocytopenia delays periodontal healing in rats with periodontal disease: participation of endostatin and vascular endothelial growth factor

BACKGROUND AND OBJECTIVE

Platelets contain factors, including VEGF and endostatin, that can modulate the healing process. We evaluated the effects of severe thrombocytopenia on periodontal healing in rats and determined the contribution of VEGF and endostatin to the healing process.

MATERIAL AND METHODS

Rats were distributed into three test groups and two control groups. Cotton ligatures were placed at the gingival margin level of the lower first molar in the test groups. Sham-operated rats and rats in one of the periodontitis groups were killed 15 days later. Rats in the remaining two periodontitis groups had the ligatures removed in order to study the spontaneous recovery from the periodontal disease 15 days later, and these rats were treated with rabbit antiplatelet serum, in order to induce thrombocytopenia, or normal rabbit serum. An additional group without ligatures received antiplatet serum in the same period.

RESULTS

After ligature removal, rats treated with normal rabbit serum showed reduced myeloperoxidase activity, decreased alveolar bone loss and increased numbers of blood vessels. Thrombocytopenia caused a delay in alveolar bone regeneration, a decrease in the number of vessels and a modest decrease in myeloperoxidase activity. In the rats with periodontitis, serum endostatin concentrations were slightly decreased and serum VEGF remained unchanged compared with sham-operated animals. After ligature removal, a significant VEGF increase and endostatin decrease were observed in the rats treated with normal rabbit serum. Thrombocytopenia led to a dramatic fall in both VEGF and endostatin concentrations.

CONCLUSION

Thrombocytopenia leads to a delay of periodontal healing in the situation of experimental periodontitis, which might be mediated in part by a decrease in the serum concentration of VEGF and endostatin derived from the platelets. However, other factors derived from the platelets may also have contributed to a delay of periodontal healing in the rats with thrombocytopenia.

Innate immunity and toll-like receptor antagonists: a potential role in the treatment of cardiovascular diseases

Toll-like receptors (TLRs) are germline-encoded receptors that recognize various pathogen-associated molecular patterns (PAMPs). They are key components of the innate immunity which are activated in response to pathogens as well as non-pathogenic components of damaged tissues. TLR agonists have been developed to treat allergies, cancers, and chronic infections by upregulating the innate immune system. TLR antagonists may be used to treat a number of inflammatory conditions, such as rheumatoid arthritis and systemic lupus erythematosus. Recent research also has shown that TLRs are involved in the pathogenesis of atherosclerosis, thrombosis, myocardial remodeling, ischemic/reperfusion injury, and valvular disease. This article reviews the current experimental and clinical evidence for the role of TLRs in the cardiovascular system, and examines the mechanisms by which TLR antagonists could potentially be used in targeted therapy.

Statin treatment, carotid atherosclerotic plaque macrophage infiltration and circulating inflammatory markers

BACKGROUND

Statin treatment is considered as first line therapy in patients with atherosclerotic disease. We evaluated the effect of pre-treatment with statins on carotid plaque infiltration by macrophages and on the circulating levels of proinflammatory cytokines in patients who underwent carotid endarterectomy.

PATIENTS AND METHODS

One hundred fourteen patients were enrolled; 89 men and 25 women (mean age 67+/-8 years; range 42-83 years). Fifty three patients (46%) were on statin treatment at least 3 months before endarterectomy and 61 (54%) had never received statin treatment. The serum levels of high sensitivity C reactive protein (hsCRP), serum amyloid A (SAA), tumor necrosis factor alpha (TNFalpha), interleukin (IL)-1beta and IL-6 were evaluated preoperatively. The intensity of macrophage infiltration was evaluated by immunochemistry, using the monoclonal antibody CD 68. The area of the plaque covered by macrophages was measured as a proportion of the whole plaque area, using a custom designed image tool analysis.

RESULTS

Patients on statins had lower serum total cholesterol levels (172+/-50 vs 194+/-35 mg/dl, p= 0.014), lower low density cholesterol levels (103+/-44 vs 123+/-31 mg/dl, p= 0.010) and lower serum hsCRP levels (1.8 [1.1-3.4] vs 3.4 [1.3-4.9] mg/l, p= 0.03), while SAA, TNFalpha, IL-6 and IL-1beta levels did not differ between the 2 groups. The infiltration of atherosclerotic plaque by macrophages was similar in statin treated patients and in controls (0.55+/-0.15% vs 0.49+/-0.19%, p= 0.21).

CONCLUSION

Patients on statins have similar macrophage accumulation in their carotid atherosclerotic plaques compared with patients not on statins. Inflammatory markers were also similar in both groups except for hsCRP which was significantly lower in those taking statins.