Association of rheumatic fever & rheumatic heart disease with plausible early & late-stage disease markers

Plausible Role of NLRP3 Inflammasome and Associated Cytokines in Pathogenesis of Rheumatic Heart Disease

Rheumatic heart disease (RHD) is a post-streptococcal sequela caused by Streptococcus pyogenes. The global burden of disease is high among people with low socio-economic status, with significant cases emerging every year despite global eradication efforts. The current treatment includes antibiotic therapies to target strep throat and rheumatic fever and valve replacement strategies as a corrective measure for chronic RHD patients. Valvular damage and valve calcification are considered to be the end-stage processes of the disease resulting from impairment of the endothelial arrangement due to immune infiltration. This immune infiltration is mediated by a cascade of events involving NLRP3 inflammasome activation. NLRP3 inflammasome is activated by wide range of stimuli including bacterial cell wall components like M proteins and leukocidal toxins like nicotinamide dehydrogenase (NADase) and streptolysin O (SLO) and these play a major role in sustaining the virulence of Streptococcus pyogenes and progression of RHD. In this review, we are discussing NLRP3 inflammasome and its plausible role in the pathogenesis of RHD by exploiting the host-pathogen interaction mainly focusing on the NLRP3 inflammasome-mediated cytokines IL-1β and IL-18. Different therapeutic approaches involving NLRP3 inflammasome inactivation, caspase-1 inhibition, and blockade of IL-1β and IL-18 are discussed in this review and may be promising for treating RHD patients.

The Immune and Inflammatory Basis of Acquired Pediatric Cardiac Disease

Children with acquired heart disease face significant health challenges, including a lifetime of strict medical management, multiple cardiac surgeries, and a high mortality risk. Though the presentation of these conditions is diverse, a unifying factor is the role of immune and inflammatory responses in their development and/or progression. For example, infectious agents have been linked to pediatric cardiovascular disease, leading to a large health burden that disproportionately affects low-income areas. Other implicated mechanisms include antibody targeting of cardiac proteins, infection of cardiac cells, and inflammation-mediated damage to cardiac structures. These changes can alter blood flow patterns, change extracellular matrix composition, and induce cardiac remodeling. Therefore, understanding the relationship between the immune system and cardiovascular disease can inform targeted diagnostic and treatment approaches. In this review, we discuss the current understanding of pediatric immune-associated cardiac diseases, challenges in the field, and areas of research with potential for clinical benefit.

Rheumatic heart disease: A review of the current status of global research activity

Rheumatic heart disease (RHD) is a serious and long-term consequence of acute rheumatic fever (ARF), an autoimmune sequela of a mucosal infection by Streptococcus pyogenes (Group A Streptococcus, Strep A). The pathogenesis of ARF and RHD is complex and not fully understood but involves host and bacterial factors, molecular mimicry, and aberrant host innate and adaptive immune responses that result in loss of self-tolerance and subsequent cross-reactivity with host tissues. RHD is entirely preventable yet claims an estimated 320 000 lives annually. The major burden of disease is carried by developing nations and Indigenous populations within developed nations, including Australia. This review will focus on the epidemiology, pathogenesis and treatment of ARF and RHD in Australia, where: streptococcal pyoderma, rather than streptococcal pharyngitis, and Group C and Group G Streptococcus, have been implicated as antecedents to ARF; the rates of RHD in remote Indigenous communities are persistently among the highest in the world; government register-based programs coordinate disease screening and delivery of prophylaxis with variable success; and researchers are making significant progress in the development of a broad-spectrum vaccine against Strep A.

Matrix metalloproteinase-9 in pediatric rheumatic heart disease with and without heart failure

In cardiovascular disorders, the myocardium may be subjected to the breakdown and remodeling of collagen by metalloproteinase-9 (MMP-9). We hypothesized that the serum MMP-9 concentration may be elevated in pediatric patients with rheumatic heart disease (RHD) and heart failure (HF), and its level can be correlated with the HF severity. Thus, in the present study, we aimed to evaluate the sensitivity and accuracy of MMP-9 to predict HF in children with RHD and to determine its effectiveness as an indicator of the degree of HF. This study included 98 consecutive children admitted to the Department of Pediatrics, Zagazig University Hospital, Al Sharqia Governorate, Egypt with newly diagnosed RHD. Their ages ranged from 8.5 to 16 years. Fifty-eight children had RHD without HF while 40 children were complicated with HF which was diagnosed clinically and by echocardiography. A total of 44 healthy children were enrolled as a control group. MMP-9 serum levels were estimated by enzyme-linked immunosorbent assay. The serum MMP-9 concentration was higher in the RHD without HF and RHD with HF groups than this level noted in the control (P<0.001). MMP-9 was a significant predictor of HF; area under the curve (AUC)=0.85 [95% confidence interval (CI), 0.76-0.94]. At the level of 386.9 ng/ml, MMP-9 detected HF with a sensitivity 95% (95% CI, 83.08-99.39), specificity 74.14% (95% CI, 60.96-84.74), positive predictive value 71.70% (95% CI, 61.96-79.75), negative predictive value 95.56% (95% CI, 84.67-98.82) and accuracy 82.65% (95% CI, 73.69-89.56). In addition, MMP-9 showed a significant negative correlation with ejection fraction and fractional shortening (P=0.01 and P=0.02, respectively). In conclusion; MMP-9 may be an independent sensitive marker with which to detect HF in children with RHD and it can predict the prognoses of these patients as it correlates with the severity of HF. Further studies considering MMP-9 in the detection of 'silent' RHD in school aged children and asymptomatic HF in children with known RHD especially in rural areas, are highly recommended.

Circulating cytokines predict severity of rheumatic heart disease

BACKGROUND

Rheumatic heart disease (RHD) is associated with inflammation that damages cardiac valves, often requiring surgical interventions. The underlying mechanisms involved in the disease progression are not completely understood. This study aimed to evaluate cytokine plasma levels in patients with RHD as possible markers of disease severity.

METHODS AND RESULTS

Eighty-nine patients with RHD, age of 41 years ±11.5 years, were prospectively enrolled. RHD severity was defined as valve dysfunction that required invasive intervention, either valve repair or replacement. Peripheral blood samples were collected from all patients for cytokine measurements. The patients were followed up to look at adverse clinical events defined as either the need for valve intervention or death. At baseline, 64 (71.9%) patients had previously undergone valve intervention, whereas 25 patients had stable clinical presentation. Patients with severe RHD displayed higher levels of inflammatory cytokines than patients with stable disease. Cluster analysis showed segregation of severe and stable RHD based on IL-6/TNF-α and IL-6/IL-17A, respectively. IL-6 and TNF-α expression were positively correlated in severe but not in stable RHD patients. During a median follow-up of 23 months, 16 patients (18%) had an adverse outcome. IL-10 at baseline (HR 1.24, 95% CI 1.08-1.43, p = 0.003), and IL-4 (HR 1.12, 95% CI 1.01-1.24, p = 0.041) were predictors of events during the follow-up.

CONCLUSIONS

High levels of cytokines are associated with severity of RHD. The co-regulated expression of IL-6 and TNF-α is associated with severe valve dysfunction, whereas high IL-10 and IL-4 levels predicted subsequently adverse outcome.

Anti-endothelial cell antibody rich sera from rheumatic heart disease patients induces proinflammatory phenotype and methylation alteration in endothelial cells

Rheumatic heart disease (RHD) is a major cause of cardiovascular morbidity and mortality in developing nations like India. RHD commonly affects the mitral valve which is lined by a single layer of endothelial cells (ECs). The role of ECs in mitral valve damage during RHD is not well elucidated. In here, anti-endothelial cell antibody from RHD patients has been used to stimulate the ECs (HUVECs and HMVECs). ECs proinflammatory phenotype with increased expression of TNFα, IL-6, IL-8, IFNγ, IL-1β, ICAM1, VCAM1, E-selectin, laminin B, and vimentin was documented in both ECs. The promoter hypomethylation of various key inflammatory cytokines (TNFα, IL-6, and IL-8), integrin (ICAM1) associated with leukocyte transendothelial migration, and extracellular matrix genes (vimentin, and laminin) were also observed. Further, the in-vitro data was in accordance with ex-vivo observations which correlated significantly with the etiological factors such as smoking, socioeconomic status, and housing. Thus, the study sheds light on the role of ECs in RHD which is a step forward in the elucidation of disease pathogenesis.