Increased Circulating Endothelin-1 in Rheumatic Mitral Stenosis

Update on rheumatic heart disease

PURPOSE OF REVIEW

The purpose is to provide a broad overview of the current state of knowledge of pathogenesis, diagnosis, and management of rheumatic heart disease (RHD).

RECENT FINDINGS

Studies on pathogenesis of RHD have focused on autoimmunity because of molecular mimicry between the streptococcal M antigen α-helical coiled-coil structure and sarcomeric proteins such as myosin and tropomyosin. More recently, nonsarcomeric autoantigens, endothelial injury and the innate immune system have been proposed to play key roles in the pathogenesis of RHD. In the 2015 revised Jones Criteria, the importance of echocardiography and subclinical carditis in the diagnosis of acute rheumatic fever is highlighted. Experimental studies with targeted anti-inflammatory therapeutics have been largely unsuccessful and the only established treatment is still lifelong antibiotics. Efforts to improve patient selection and outcomes with percutaneous mitral balloon valvuloplasty are ongoing. With regard to surgical management, several groups have demonstrated excellent operative and midterm outcomes from valve repair as opposed to valve replacement.

SUMMARY

There are still many unanswered questions regarding RHD pathogenesis. The only accepted medical treatment is still long-term antibiotic therapy, whereas advances in mitral repair techniques have led to successful durable repairs being performed in high-volume, expert centers.

Analysis of immunostaining and western blotting of endothelin 1 and its receptors in mitral stenosis

INTRODUCTION

Rheumatic Fever represents a serious public health problem in developing countries, with thousands of new cases each year. It is an autoimmune disease, which occurs in response to infection by streptococcus A.

OBJECTIVE

The aim of this study was to evaluate the immunolabeling and protein expression for endothelin-1 and 3 (ET-1, ET-3) and its receptors (ETA, ETB) in rheumatic mitral valves.

METHODS

Immunohistochemistry was used to identify ET-1/ET-3 and ETA/ETB receptors in rheumatic and control mitral valves. Quantitative analysis of immunostaining for ET-1/ET-3 and ETA/ETB receptors was performed. In addition, western blot analysis was carried out to assess protein levels in tissue samples.

RESULTS

ET-1 and ETA receptor immunostaining predominated in stenotic valves, mainly associated with fibrotic regions, inflammatory areas and neovascularization. Quantitative analysis showed that the average area with positive expression of ET-1 was 18.21 ± 14.96%. For ETA and ETB, the mean expressed areas were respectively 15.06 ± 13.13% and 9.20 ± 11.09%. ET-3 did not have a significant expression. The correlation between the expression of both endothelin receptors were strongly positive (R = 0.74, P = 0.02), but the correlation between ET-1 and its receptor were negative for both ETA (R = -0.37, P = 0.25), and ETB (R = -0.14, P = 0.39). This data was supported by western blot analysis.

CONCLUSION

The strong correlation between ET-1 and its receptors suggests that both play a role in the pathophysiology of rheumatic mitral valve stenosis and may potentially act as biomarkers of this disease.

IL-10 and ET-1 as biomarkers of rheumatic valve disease

OBJECTIVE

To evaluate the immunological profile and gene expression of endothelin-1 (ET-1) in mitral valves of patients with rheumatic fever originated from a reference service in cardiovascular surgery.

METHODS

This was a quantitative, observational and cross-sectional study. Thirty-five subjects (divided into four groups) participated in the study, 25 patients with chronic rheumatic heart disease and ten control subjects. The mean age of the sample studied was 34.5 years. Seventeen of them (48.58%) were male and 18 (51.42%) were female. Inflammatory cytokines (TNF-α, IL-4 and IL-10) were measured and ten mitral valves of patients who underwent first valve replacement were collected for determination of gene expression of endothelin-1 by real time PCR.

RESULTS

Among the groups studied (patients vs. controls), there was a statistically significant difference in IL-10 levels (P=0.002), and no differences in other cytokines. Expression of endothelin-1 was observed in 70% of samples. Quantitatively, average of ET-1 expression was 62.85±25.63%.

CONCLUSION

Inflammatory cytokine IL-10 participates in the maintenance of chronicity of rheumatic fever in patients who underwent valve replacement and those who are undergoing medical treatment. The expression of endothelin-1 in heart valve lesions in patients undergoing mitral valve replacement confirms its association with inflammatory activity in rheumatic fever.

Rheumatic mitral valve stenosis is associated with impaired flow-mediated dilatation

It has been demonstrated that rheumatic mitral valve stenosis (RMVS) is associated with an increase in markers of endothelial dysfunction. It is not known whether this association indicates an impairment of flow-mediated dilatation (FMD) of the vascular endothelium. Thirty patients with RMVS and 30 healthy subjects were studied. FMD in patients with RMVS was significantly smaller than in healthy controls (11.9+/-0.4% vs 15.4+/-0.70%, p=0.003). The absolute change in brachial artery diameter in patients with RMVS was also significantly smaller than in healthy subjects (0.42+/-0.26 mm vs 0.64+/-0.32 mm, p<0.001). These findings suggest that vascular endothelial function is altered in patients with RMVS.

Prognostic Value of Circulating Levels of Endothelin-1 in Patients After Acute Myocardial Infarction Undergoing Primary Coronary Angioplasty

BACKGROUND

The link between increased circulating level of endothelin (ET)-1 and adverse clinical outcomes after acute myocardial infarction (AMI) has been established. Current studies demonstrate that reperfusion therapy by either thrombolysis or primary percutaneous coronary intervention (PCI) can salvage myocardium, improving survival of AMI patients. However, whether reperfusion therapy by primary PCI can prevent the adverse effect of ET-1 on clinical outcomes in patients after AMI remains unclear. Therefore, this study examined the predictive value of circulating ET-1 levels on 30-day outcomes in ST-segment elevated AMI treated with primary PCI.

METHODS AND RESULTS

We conducted a prospective cohort study of 186 consecutive patients with ST-segment elevated AMI of onset < 12 h who underwent primary PCI. Blood samples for plasma concentration of ET-1 were collected in the catheterization laboratory following vascular puncture. Patients were classified into a high group (group 1, ET-1 level >or= 0.632 pg/mL, n = 93) and a low group (group 2, ET-1 level < 0.632 pg/mL, n = 93) according to the median value of ET-1 after AMI. Univariate analysis demonstrated that the 30-day composite major adverse clinical outcomes (MACO) [advanced Killip score >or= 3], severe congestive heart failure (CHF) [New York Heart Association functional class 4], and 30-day mortality were strongly associated with high ET-1 level (>or= 0.632 pg/mL; p < 0.0001), unsuccessful reperfusion (final Thrombolysis in Myocardial Infarction flow <or= 2; p < 0.0001), low left ventricular ejection fraction (< 50%; p = 0.0002), multivessel disease (p = 0.005), and female gender (p = 0.007). Multiple stepwise logistic regression analysis demonstrated that only high ET-1 level (p < 0.0001) and unsuccessful reperfusion (p < 0.0001) were independent predictors of 30-day MACO. Additionally, high ET-1 level (p = 0.0021) along with unsuccessful reperfusion (p = 0.008) and severe CHF (p < 0.0001) were significant independent predictors of increased 30-day mortality.

CONCLUSIONS

A high circulating level of ET-1 is a strong independent predictor of 30-day MACO after ST-segment elevated AMI treated with primary PCI.