Genes, autoimmunity and pathogenesis of rheumatic heart disease

T-Cell Receptor Sequences Identify Combined Coxsackievirus-Streptococci Infections as Triggers for Autoimmune Myocarditis and Coxsackievirus-Clostridia Infections for Type 1 Diabetes

Recent research suggests that T-cell receptor (TCR) sequences expanded during human immunodeficiency virus and SARS-CoV-2 infections unexpectedly mimic these viruses. The hypothesis tested here is that TCR sequences expanded in patients with type 1 diabetes mellitus (T1DM) and autoimmune myocarditis (AM) mimic the infectious triggers of these diseases. Indeed, TCR sequences mimicking coxsackieviruses, which are implicated as triggers of both diseases, are statistically significantly increased in both T1DM and AM patients. However, TCRs mimicking Clostridia antigens are significantly expanded in T1DM, whereas TCRs mimicking Streptococcal antigens are expanded in AM. Notably, Clostridia antigens mimic T1DM autoantigens, such as insulin and glutamic acid decarboxylase, whereas Streptococcal antigens mimic cardiac autoantigens, such as myosin and laminins. Thus, T1DM may be triggered by combined infections of coxsackieviruses with Clostridia bacteria, while AM may be triggered by coxsackieviruses with Streptococci. These TCR results are consistent with both epidemiological and clinical data and recent experimental studies of cross-reactivities of coxsackievirus, Clostridial, and Streptococcal antibodies with T1DM and AM antigens. These data provide the basis for developing novel animal models of AM and T1DM and may provide a generalizable method for revealing the etiologies of other autoimmune diseases. Theories to explain these results are explored.

The Immunomodulatory Role of Microbiota in Rheumatic Heart Disease: What Do We Know and What Can We Learn from Other Rheumatic Diseases?

Rheumatic heart disease (RHD) represents a serious cardiac sequela of acute rheumatic fever, occurring in 30-45% of patients. RHD is multifactorial, with a strong familial predisposition and known environmental risk factors that drive loss of immunological tolerance. The gut and oral microbiome have recently been implicated in the pathogenesis of RHD. Disruption of the delicate balance of the microbiome, or dysbiosis, is thought to lead to autoimmune responses through several different mechanisms including molecular mimicry, epitope spreading, and bystander activation. However, data on the microbiomes of RHD patients are scarce. Therefore, in this comprehensive review, we explore the various dimensions of the intricate relationship between the microbiome and the immune system in RHD and other rheumatic diseases to explore the potential effect of microbiota on RHD and opportunities for diagnosis and treatment.

Clostridia and Enteroviruses as Synergistic Triggers of Type 1 Diabetes Mellitus

What triggers type 1 diabetes mellitus (T1DM)? One common assumption is that triggers are individual microbes that mimic autoantibody targets such as insulin (INS). However, most microbes highly associated with T1DM pathogenesis, such as coxsackieviruses (COX), lack INS mimicry and have failed to induce T1DM in animal models. Using proteomic similarity search techniques, we found that COX actually mimicked the INS receptor (INSR). Clostridia were the best mimics of INS. Clostridia antibodies cross-reacted with INS in ELISA experiments, confirming mimicry. COX antibodies cross-reacted with INSR. Clostridia antibodies further bound to COX antibodies as idiotype-anti-idiotype pairs conserving INS-INSR complementarity. Ultraviolet spectrometry studies demonstrated that INS-like Clostridia peptides bound to INSR-like COX peptides. These complementary peptides were also recognized as antigens by T cell receptor sequences derived from T1DM patients. Finally, most sera from T1DM patients bound strongly to inactivated Clostridium sporogenes, while most sera from healthy individuals did not; T1DM sera also exhibited evidence of anti-idiotype antibodies against idiotypic INS, glutamic acid decarboxylase, and protein tyrosine phosphatase non-receptor (islet antigen-2) antibodies. These results suggest that T1DM is triggered by combined enterovirus-Clostridium (and possibly combined Epstein-Barr-virus-Streptococcal) infections, and the probable rate of such co-infections approximates the rate of new T1DM diagnoses.

IgG2 rules: N-acetyl-β-D-glucosamine-specific IgG2 and Th17/Th1 cooperation may promote the pathogenesis of acute rheumatic heart disease and be a biomarker of the autoimmune sequelae of Streptococcus pyogenes

Antecedent group A streptococcal pharyngitis is a well-established cause of acute rheumatic fever (ARF) where rheumatic valvular heart disease (RHD) and Sydenham chorea (SC) are major manifestations. In ARF, crossreactive antibodies and T cells respond to streptococcal antigens, group A carbohydrate, N-acetyl-β-D-glucosamine (GlcNAc), and M protein, respectively, and through molecular mimicry target heart and brain tissues. In this translational human study, we further address our hypothesis regarding specific pathogenic humoral and cellular immune mechanisms leading to streptococcal sequelae in a small pilot study. The aims of the study were to (1) better understand specific mechanisms of pathogenesis in ARF, (2) identify a potential early biomarker of ARF, (3) determine immunoglobulin G (IgG) subclasses directed against GlcNAc, the immunodominant epitope of the group A carbohydrate, by reaction of ARF serum IgG with GlcNAc, M protein, and human neuronal cells (SK-N-SH), and (4) determine IgG subclasses deposited on heart tissues from RHD. In 10 pediatric patients with RHD and 6 pediatric patients with SC, the serum IgG2 subclass reacted significantly with GlcNAc, and distinguished ARF from 7 pediatric patients with uncomplicated pharyngitis. Three pediatric patients who demonstrated only polymigrating arthritis, a major manifestation of ARF and part of the Jones criteria for diagnosis, lacked the elevated IgG2 subclass GlcNAc-specific reactivity. In SC, the GlcNAc-specific IgG2 subclass in cerebrospinal fluid (CSF) selectively targeted human neuronal cells as well as GlcNAc in the ELISA. In rheumatic carditis, the IgG2 subclass preferentially and strongly deposited in valve tissues (n = 4) despite elevated concentrations of IgG1 and IgG3 in RHD sera as detected by ELISA to group A streptococcal M protein. Although our human study of ARF includes a very small limited sample set, our novel research findings suggest a strong IgG2 autoantibody response against GlcNAc in RHD and SC, which targeted heart valves and neuronal cells. Cardiac IgG2 deposition was identified with an associated IL-17A/IFN-γ cooperative signature in RHD tissue which displayed both IgG2 deposition and cellular infiltrates demonstrating these cytokines simultaneously. GlcNAc-specific IgG2 may be an important autoantibody in initial stages of the pathogenesis of group A streptococcal sequelae, and future studies will determine if it can serve as a biomarker for risk of RHD and SC or early diagnosis of ARF.

Recent Advances in the Rheumatic Fever and Rheumatic Heart Disease Continuum

Nearly a century after rheumatic fever (RF) and rheumatic heart disease (RHD) was eradicated from the developed world, the disease remains endemic in many low- and middle-income countries (LMICs), with grim health and socioeconomic impacts. The neglect of RHD which persisted for a semi-centennial was further driven by competing infectious diseases, particularly the human immunodeficiency virus (HIV) pandemic. However, over the last two-decades, slowly at first but with building momentum, there has been a resurgence of interest in RF/RHD. In this narrative review, we present the advances that have been made in the RF/RHD continuum over the past two decades since the re-awakening of interest, with a more concise focus on the last decade’s achievements. Such primary advances include understanding the genetic predisposition to RHD, group A Streptococcus (GAS) vaccine development, and improved diagnostic strategies for GAS pharyngitis. Echocardiographic screening for RHD has been a major advance which has unearthed the prevailing high burden of RHD and the recent demonstration of benefit of secondary antibiotic prophylaxis on halting progression of latent RHD is a major step forward. Multiple befitting advances in tertiary management of RHD have also been realized. Finally, we summarize the research gaps and provide illumination on profitable future directions towards global eradication of RHD.

Relationship between Environmental Factors and Rheumatic Heart Disease

Background. Rheumatic fever (RF) and rheumatic heart disease (RHD) are the most common acquired heart diseases in children. Environmental factors have been reported to play an important role in RHD’s prevalence Aim. The main purpose of this study is to assess the associations between environmental factors and RHD in children. Methods. A case control study was conducted in the Department of Child Health, Haji Adam Malik Hospital from April to June 2017. The case group consisted of children aged 5-18 years with RHD while control group consisted of healthy children. Demographic, anthropometric, and laboratory data were collected along with environmental factors. Statistical analysis was done using Statistical Product and Service Solution (SPSS). A P value of <0,05 with 95% confidence interval was considered significant. Results. A total of 39 children were enrolled in each group. Subjects’ father who only went to elementary and junior high school had a higher risk of having children with RHD (OR 28; p = 0.032 and OR 15.75; p = 0.011, respectively). Subjects’ mother who only went to junior high school had 7 times higher risk of having children with RHD (p = 0.026). Low monthly income increased the risk of RHD (OR 3,68; p = 0,009). Tap water usage, meat consumption more than once per week, and feasibility to buy clothes >1 pair per year decreased the risk of RHD at 0,31 (p = 0,013), 0,3 (p = 0,016), and 0,04 times (p <0,001) respectively. Conclusion. Parent’s education, monthly family income, water source, frequency of meat consumption, and feasibility to buy clothes are related to RHD in children.

The Genetic Control of the Rheumatic Heart: Closing the Genotype-Phenotype Gap

Rheumatic heart disease (RHD) is a heritable inflammatory condition characterized by carditis, arthritis, and systemic disease. Although remaining neglected, the last 3 years has seen some promising advances in RHD research. Whilst it is clear that RHD can be triggered by recurrent group A streptococcal infections, the mechanisms driving clinical progression are still poorly understood. This review summarizes our current understanding of the genetics implicated in this process and the genetic determinants that predispose some people to RHD. The evidence demonstrating the importance of individual cell types and cellular states in delineating causal genetic variants is discussed, highlighting phenotype/genotype correlations where possible. Genetic fine mapping and functional studies in extreme phenotypes, together with large-scale omics studies including genomics, transcriptomics, epigenomics, and metabolomics, are expected to provide new information not only on RHD but also on the mechanisms of other autoimmune diseases and facilitate future clinical translation.

Cytokine gene functional polymorphisms and phenotypic expression as predictors of evolution from latent to clinical rheumatic heart disease

INTRODUCTION

Inflammation associated with rheumatic heart disease (RHD) is influenced by gene polymorphisms and inflammatory cytokines. There are currently no immunologic and genetic markers to discriminate latent versus clinical patients, critical to predict disease evolution. Employing machine-learning, we searched for predictors that could discriminate latent versus clinical RHD, and eventually identify latent patients that may progress to clinical disease.

METHODS

A total of 212 individuals were included, 77 with latent, 100 with clinical RHD, and 35 healthy controls. Circulating levels of 27 soluble factors were evaluated using Bio-Plex ProTM® Human Cytokine Standard 27-plex assay. Gene polymorphism analyses were performed using RT-PCR for the following genes: IL2, IL4, IL6, IL10, IL17A, TNF and IL23.

RESULTS

Serum levels of all cytokines were higher in clinical as compared to latent RHD patients, and in those groups than in controls. IL-4, IL-8, IL-1RA, IL-9, CCL5 and PDGF emerged in the final multivariate model as predictive factors for clinical, compared with latent RHD. IL-4, IL-8 and IL1RA had the greater power to predict clinical RHD. In univariate analysis, polymorphisms in IL2 and IL4 were associated with clinical RHD and in the logistic analysis, IL6 (GG + CG), IL10 (CT + TT), IL2 (CA + AA) and IL4 (CC) genotypes were associated with RHD.

CONCLUSION

Despite higher levels of all cytokines in clinical RHD patients, IL-4, IL-8 and IL-1RA were the best predictors of clinical disease. An association of polymorphisms in IL2, IL4, IL6 and IL10 genes and clinical RHD was observed. Gene polymorphism and phenotypic expression of IL-4 accurately discriminate latent versus clinical RHD, potentially instructing clinical management.

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.

Ficolin-3 in rheumatic fever and rheumatic heart disease

Rheumatic fever (RF) and chronic rheumatic heart disease (RHD) are complications of oropharyngeal infection caused by Streptococcus pyogenes. Despite the importance of the complement system against infections and autoimmunity diseases, studies on the role of the lectin pathway in RF and RHD are scarce. Thus, our aim was to evaluate the association of ficolin-3 serum levels, FCN3 polymorphisms and haplotypes with the susceptibility to RF and RHD. We investigated 179 patients with a history of RF (126 RHD and 53 RF only) and 170 healthy blood donors as control group. Ficolin-3 serum concentrations were measured using enzyme-linked immunosorbent assay (ELISA). Three FCN3 single nucleotide polymorphisms (SNPs rs532781899, rs28362807 and rs4494157) were genotyped through the sequence-specific PCR method. Lower ficolin-3 serum levels were observed in RF patients when compared to controls (12.81 μg/mL vs. 18.14 μg/mL respectively, p < 0.0001, OR 1.22 [1.12-1.34]), and in RHD in comparison to RF only (RFo) (12.72 μg/mL vs. 14.29 μg/mL respectively, p = 0.016, OR 1.38 [1.06-1.80]). Low ficolin-3 levels (<10.7 μg/mL) were more common in patients (39.5 %, 30/76) than controls (20.6 %, 13/63, p = 0.018, OR = 2.51 [1.14-5.31]), and in RHD (44.4 %, 28/63) than RFo (15.4 %, 2/13, p = 0.007, OR = 3.08 [1.43-6.79]). On the other hand, FCN3 polymorphism/haplotypes were not associated with ficolin-3 serum levels or the disease. Low ficolin-3 levels might be associated with RF, being a potential marker of disease progression.

Pattern of Cardiac Diseases and Co-Existing Morbidities Among Newly Registered Cardiac Patients in an Adult Cardiac Referral Clinic of Hawassa University Comprehensive Specialized Hospital, Southern-Ethiopia

Background

Currently, cardiovascular diseases (CVDs) are rising in the world and require great concern because the consequences are not only morbidity and mortality, but also a high economic burden. However, the pattern of CVDs in Ethiopia is not well known. Therefore, this study aimed to describe CVD and co-existing morbidities among newly registered cardiac patients in Hawassa University Comprehensive Specialized Hospital.

Methods

A retrospective cross-sectional study was conducted from January 1 to December 31, 2016 among newly registered cardiac patients in an adult cardiac referral clinic. Records and cardiac referral clinic logbooks were used to collect relevant information using structured checklists.

Results

Of the total 310 records of cardiac patients, 236 were explored and included in the study, while the records of 74 patients were absent in the cards room when tracing and/or incomplete to assess cardiac pattern. Rheumatic heart disease (RHD) was the leading cardiac problem and diagnosed in 70 (29.7%) cases followed by non-ischemic cardiomyopathy (55, 23.3%), ischemic heart disease (41, 17.4%), hypertensive heart disease (29, 12.3%), and cor pulmonale (14, 5.9%). The mean age of RHD patients was 28.7 (±13.1) years. Eighty-two (35%) females and 23 (19.8%) males had RHD, while 69 (29.2%) females and 23 (19.8%) males had non-ischemic cardiomyopathy. The overall rate of mitral stenosis, mitral regurgitation, and aortic regurgitation among patients with RHD were 39 (55.7%), 48 (68.6%), and 26 (37.1%), respectively. Moreover, the overall coexisted morbidity was 81 (34.3%), with a high rate of hypertension alone at 44 (18.6%) followed by hypertension with diabetes at 11 (4.7%).

Conclusion

This study indicated that more than one-third of cardiac patients had at least one of the co-existing morbidities like hypertension, diabetes mellitus, asthma and other diseases. Therefore, careful diagnosis and management of cardiac patients plays an important role to minimize comorbidity-linked complications. Moreover, population-based studies are recommended for better representing and generalization.

Throat Colonization and Antibiotic Susceptibility of Group a β-Hemolytic Streptococci Among Rheumatic Heart Disease Patients Attending a Cardiac Referral Hospital in Tanzania, a Descriptive Cross-Sectional Study

Background: Secondary prophylaxis against repeated attacks of acute rheumatic fever is an important intervention in patients with rheumatic heart disease (RHD), and it aims to prevent throat infection by group A β-hemolytic streptococcus (GAS); however, its implementation faces many challenges. This study aimed to assess throat colonization, antibiotic susceptibility, and factors associated with GAS colonization among patients with RHD attending care at Jakaya Kikwete Cardiac Institute in Dar-es-Salaam, Tanzania.

Methods: A descriptive cross-sectional study of RHD patients attending the Jakaya Kikwete Cardiac Institute was conducted from March to May 2018, where we consecutively enrolled all patients known to have RHD and coming for their regular clinic follow-up. A structured questionnaire was used to obtain patients' sociodemographic information, factors associated with GAS colonization, and status of secondary prophylaxis use and adherence. Throat swabs were taken and cultured to determine the presence of GAS, and isolates of GAS were tested for antibiotic susceptibility using Kirby–Bauer disk diffusion method according to the Clinical and Laboratory Standards Institute version 2015. Antibiotics of interest were chosen according to the Tanzanian Treatment Guidelines.

Results: In total, 194 patients with RHD were enrolled, their mean age was 28.4 ± 16.5 years, and 58.2% were females. Only 58 (29.9%) patients were on regular prophylaxis, 39 (20.1%) had stopped taking prophylaxis, whereas 97 (50.0%) had never been on prophylaxis. Throat cultures were positive for GAS in 25 (12.9%) patients. Patients who stopped prophylaxis were 3.26 times more likely to be colonized by GAS when compared to patients on regular prophylaxis. Majority (96%) of GAS isolates were susceptible to penicillin, ceftriaxone, and ciprofloxacin, whereas the highest resistance (20%) was observed with vancomycin. No GAS resistance was observed against penicillin.

Conclusion: The prevalence of GAS throat colonization is high among this population and is associated with stopping prophylaxis. The proportion of patients on regular secondary prophylaxis is unacceptably low, and interventions should target both patients' and physicians' barriers to effective secondary prophylaxis.

A novel aspect may explain the mechanisms of pathogenicity of rheumatic fever, a multifactorial, autoimmune, infectious and inflammatory disorder which "licks the joints and bites the heart": A working hypothesis

A novel hypothesis is presented to explain the pathogenesis of the multifactorial autoimmune disorder rheumatic fever (RF). It involves a synergistic interaction among streptococcal toxins, their cell wall components, M protein, immune complexes, complement components, cationic histones. These agents can act with cationic histones released by neutrophils during NETosis and bacteriolysis and can function as opsonic agents possessing properties similar to antibodies. Cationic histones can interact by strong electrostatic forces with negatively- charged domains on immune complexes and complement components. This allows their deposition and endocytosis in the myocardium, the heart valves, and in the joints. However, the main cause of cell and tissue damage observed in RF is due to a synergism among the plethora of pro-inflammatory substances released by activated neutrophils and macrophages. Cell damage may be mitigated to some extent by anionic heparins, heparinoids, and by anti-inflammatory drugs such as corticosteroids which counteract neutrophils and macrophage chemotaxis induced by cytokines.

Angiotensin Converting Enzyme Inhibitors (ACEIs) Decrease the Progression of Cardiac Fibrosis in Rheumatic Heart Disease Through the Inhibition of IL-33/sST2

Rheumatic heart disease (RHD) is common in developing countries and poses a big medical challenge and burden. The pathogenesis of RHD is influenced by the triad of host, agent, and environment. Autoantigens generated from Group A Streptococcus (GAS) infection are captured by the resident dendritic cells (DCs) in the heart's valvular endothelium. DCs differentiate into antigen presenting cells (APC) in the valve interstices. APC induces activation of autoreactive T cells, which triggers inflammation and tissue fibrosis. Cardiac fibrosis is promoted through the activation of Mitogen activated protein kinases (MAPKs) and its downstream signaling, including its interaction with transforming growth factor-β (TGF-β) and Smad proteins. TGF-β-induced phosphorylation of Smad2 complexes with Smad3 and Smad4, and translocates into the nucleus. Angiotensin II enhances the migration, maturation, and presentation of DC. In RHD, Angiotensin II induces fibrosis via the stimulation of TGF-β, which further increases the binding of IL-33 to sST2 but not ST2L, resulting in the upregulation of Angiotensin II and progression of cardiac fibrosis. This cascade of inflammation and valvular fibrosis causes calcification and stiffening of the heart valves in RHD. Angiotensin converting enzyme inhibitors (ACEIs) inhibit Angiotensin II production, which in turn decreases TGF-β expression and the onset of overt inflammatory response. This condition leads to a reduction in the sST2 as the decoy receptor to "steal" IL-33, and IL-33 binds to ST2L and results in cardioprotection against cardiac fibrosis in the pathogenesis of RHD.

Stochastic dynamics in a time-delayed model for autoimmunity

In this paper we study interactions between stochasticity and time delays in the dynamics of immune response to viral infections, with particular interest in the onset and development of autoimmune response. Starting with a deterministic time-delayed model of immune response to infection, which includes cytokines and T cells with different activation thresholds, we derive an exact delayed chemical master equation for the probability density. We use system size expansion and linear noise approximation to explore how variance and coherence of stochastic oscillations depend on parameters, and to show that stochastic oscillations become more regular when regulatory T cells become more effective at clearing autoreactive T cells. Reformulating the model as an Itô stochastic delay differential equation, we perform numerical simulations to illustrate the dynamics of the model and associated probability distributions in different parameter regimes. The results suggest that even in cases where the deterministic model has stable steady states, in individual stochastic realisations, the model can exhibit sustained stochastic oscillations, whose variance increases as one gets closer to the deterministic stability boundary. Furthermore, in the regime of bi-stability, whereas deterministically the system would approach one of the steady states (or periodic solutions) depending on the initial conditions, due to the presence of stochasticity, it is now possible for the system to reach both of those dynamical states with certain probability. Biological significance of this result lies in highlighting the fact that since normally in a laboratory or clinical setting one would observe a single individual realisation of the course of the disease, even for all parameters characterising the immune system and the strength of infection being the same, there is a proportion of cases where a spontaneous recovery can be observed, and similarly, where a disease can develop in a situation that otherwise would result in a normal disease clearance.

Mitochondrial DNA Mutations and Rheumatic Heart Diseases

Acute rheumatic fever (ARF) is an autoimmune disease affecting the heart-valve endocardium in its final stage. Although rare in developing countries, ARF persists in third-world countries, particularly Senegal, where rheumatic heart diseases (RHDs) are the most common pediatric cardiovascular pathology. This study aimed to investigate mutations in MT-CYB in ARF and RHD in Senegalese patients. MT-CYB was amplified from blood samples from ARF patients at the Clinical of Thoracic and Cardiovascular Surgery of Fann National University Hospital Centre, Dakar, Senegal (control group, healthy individuals) and sequenced. More than half of the MT-CYB mutations (58.23%) were heteroplasmic. Transitions (61.67%) were more frequent than transversions (38.33%), and non-synonymous substitutions represented 38.33% of mutations. Unoperated RHD patients harbored frequent MT-CYB polymorphisms (7.14 ± 14.70 mutations per sample) and accounted for 72.73% of mutations. Paradoxically, subjects undergoing valvular replacement harbored infrequent polymorphisms (1.39 ± 2.97 mutations per patient) and lacked 36 mutations present in unoperated subjects. A genetic differentiation was observed between these two populations, and the mutations in operated subjects were neutral, while those in unoperated subjects were under positive selection. These results indicate a narrow link (perhaps even causal) between MT-CYB mutations and ARF and its complications (i.e., RHDs) and that these mutations are largely deleterious.

Health Challenges of the Pacific Region: Insights From History, Geography, Social Determinants, Genetics, and the Microbiome

The Pacific region, also referred to as Oceania, is a geographically widespread region populated by people of diverse cultures and ethnicities. Indigenous people in the region (Melanesians, Polynesians, Micronesians, Papuans, and Indigenous Australians) are over-represented on national, regional, and global scales for the burden of infectious and non-communicable diseases. Although social and environmental factors such as poverty, education, and access to health-care are assumed to be major drivers of this disease burden, there is also developing evidence that genetic and microbiotic factors should also be considered. To date, studies investigating genetic and/or microbiotic links with vulnerabilities to infectious and non-communicable diseases have mostly focused on populations in Europe, Asia, and USA, with uncertain associations for other populations such as indigenous communities in Oceania. Recent developments in personalized medicine have shown that identifying ethnicity-linked genetic vulnerabilities can be important for medical management. Although our understanding of the impacts of the gut microbiome on health is still in the early stages, it is likely that equivalent vulnerabilities will also be identified through the interaction between gut microbiome composition and function with pathogens and the host immune system. As rapid economic, dietary, and cultural changes occur throughout Oceania it becomes increasingly important that further research is conducted within indigenous populations to address the double burden of high rates of infectious diseases and rapidly rising non-communicable diseases so that comprehensive development goals can be planned. In this article, we review the current knowledge on the impact of nutrition, genetics, and the gut microbiome on infectious diseases in indigenous people of the Pacific region.

Potential involvement of S1PR1/STAT3 signaling pathway in cardiac valve damage due to rheumatic heart disease

Rheumatic heart disease (RHD) is a public health burden in developing countries. Th17 cell-associated cytokines might play a role in the pathogenesis and development of RHD, but the specific molecular mechanism is not completely understood. We investigated the potential role of sphingosine-1-phosphate receptor 1 (S1PR1)/signal transducer and activator of transcription 3 (STAT3) signaling pathway in cardiac valve damage in a rat model of RHD. We used 20 Lewis rats divided randomly into control and RHD groups. The RHD model was constructed by injecting inactivated group A Streptococci and complete Freund's adjuvant (CFA). The rats in the control group were injected with normal saline and CFA. Th17 cell-related cytokines were measured by ELISA. Fibrosis was assessed by histological examination. RT-qPCR and western blot were used to detect the expression of S1PR1 and STAT3/phosphorylated STAT3 (p-STAT3). The S1PR1/STAT3 signaling pathway was activated in the RHD model. Compared to the control group, serum levels of IL-17 and IL-21 cytokines associated with Th17 cells were increased significantly in the RHD group; the collagen volume fraction also was substantially increased. The S1PR1/STAT3 signaling pathway might be involved in RHD induced cardiac valve damage by regulating Th17 cells.

T cell subsets: an integral component in pathogenesis of rheumatic heart disease

Acute rheumatic fever (ARF) is a consequence of pharyngeal infection of group A streptococcal (GAS) infection. Carditis is the most common manifestation of ARF which occurs in 30-45% of the susceptible individuals. Overlooked ARF cases might further progress towards rheumatic heart disease (RHD) in susceptible individuals, which ultimately leads to permanent heart valve damage. Molecular mimicry between streptococcal antigens and human proteins is the most widely accepted theory to describe the pathogenesis of RHD. In the recent past, various subsets of T cells have been reported to play an imperative role in the pathogenesis of RHD. Alterations in various T cell subsets, viz. Th1, Th2, Th17, and Treg cells, and their signature cytokines influence the immune responses and are associated with pathogenesis of RHD. Association of other T cell subsets (Th3, Th9, Th22, and T_FH) is not defined in context of RHD. Several investigations have confirmed the up-regulation of adhesion molecules and thus infiltration of T cells into the heart tissues. T cells secrete both Th type 1 and type 2 cytokines and these auto-reactive T cells play a key role in progression of heart valve damage. In this review, we are going to discuss about the role of T cell subsets and their corresponding cytokines in the pathogenesis of RHD.

Rheumatic heart disease in North Darfur: an alarmingly high burden and control initiative

Rheumatic heart disease (RHD) is the most common cause of cardiac morbidity in Sudanese young people and it is particularly prevalent in Darfur area. A retrospective review of clinical and echocardiography (echo) data for children with RHD seen in Al Fashir Hospital from 2010 to 2016 was conducted. Data from the hospital statistics, outpatient and echo clinic records were collected and analysed. A control program was started based on training modules and public awareness material. In the study period, 324 patients were admitted and 3,777 patients with RHD were seen in outpatient clinics. Complications occurred in 33% of inpatients with a case fatality of 12%. Echo revealed that 83% of patients have severe disease and 50% have a combination of more than two valves affected. Training of 50 medical assistants, 30 physicians and 10 health promoters was achieved. Public awareness programs were conducted. We found a significant burden of RHD in Al Fashir Hospital. A control program was initiated that needs substantial support from governmental and nongovernmental organizations.

Contribution of cryptic epitopes in designing a group A streptococcal vaccine

A successful vaccine needs to target multiple strains of an organism. Streptococcus pyogenes is an organism that utilizes antigenic strain variation as a successful defence mechanism to circumvent the host immune response. Despite numerous efforts, there is currently no vaccine available for this organism. Here we review and discuss the significant obstacles to vaccine development, with a focus on how cryptic epitopes may provide a strategy to circumvent the obstacles of antigenic variation.

Association Between the Interferon Gamma 874 T/A Polymorphism and the Severity of Valvular Damage in Patients with Rheumatic Heart Disease

Interferon gamma (IFN-γ) is a multifunctional cytokine that plays an important role in modulating almost all phases of the immune response and may be responsible for the increased valvular fibrosis and calcification in the pathogenesis of rheumatic heart disease (RHD). The aim of this study was to investigate the possible relationship between the IFN-γ +874 T/A polymorphism and the severity of valvular damage in the Turkish population. The IFN-γ genotypes were determined in 152 RHD patients and 151 healthy controls by ARMS-PCR. Differences in genotype distribution between patients with RHD and control were evaluated by the χ² test. All statistical analyses were performed with SPSS 15.0 Software program. Frequency of the AA genotype was found to be significantly lower and the TT genotype significantly higher in the RHD group compared to controls (p = 0.002 and p = 0.018, respectively). The TT genotype was found to be significantly higher (26.8% vs. 9.1%, p = 0.009) and the AA genotype significantly lower (29.1% vs. 8.2%, p = 0.001) in the severe valvular disease (SVD) group compared to mild valvular disease group. In the SVD group, 79 patients had mitral balloon valvotomy and/or mitral valve replacement and had significantly higher TT genotype compared to patients with medical follow-up (30.4% vs. 19%, p = 0.001). The data demonstrated that TT genotype is associated with both RHD and the severity of RHD.

Bmi1 and BRG1 drive myocardial repair by regulating cardiac stem cell function in acute rheumatic heart disease

Rheumatic heart disease (RHD) occurs due to the accumulation of complications associated with rheumatic fever, and it results in high morbidity and mortality. The majority of cases of RHD are diagnosed in the chronic stages, when treatment options are limited. A small reservoir of cardiac stem cells is responsible for maintaining cardiac homeostasis and repairing tissue damage. Understanding the role of cardiac stem cells and the various proteins responsible for their functions in different pathological stages of RHD is an important area of investigation. Polycomb complex protein BMI-1 (Bmi1) and transcription activator BRG1 (BRG1) are associated with the maintenance of stemness in various types of stem cells. The present study investigated the role served by Bmi1 and BRG1 in cardiac stem cells during various pathological stages of RHD through immunohistochemistry and western blotting. A rat model of RHD was established via immunization with the Group A Streptococcus M5 protein. The rat was demonstrated to develop acute RHD 2 months after the final immunization, characterized by cardiac inflammation and tissue damage. Chronic RHD was identified 4 months after the final immunization, revealed by cardiac tissue compression and shrinkage. Expression of the cardiac stem cell marker mast/stem cell growth factor receptor kit was identified to be elevated during acute RHD, but downregulated in the chronic stages of RHD. A similar pattern of expression was revealed for Bmi1 and BRG1, indicating that they serve a role in regulating cardiac stem cell proliferation during acute RHD. These results suggest that cardiac stem cells serve a supportive role in the acute, but not chronic, stages of RHD via expression of Bmi1 and BRG1.

DNA methylation dysregulations in rheumatic heart valve disease

Background

The epigenetic changes underlying the development of rheumatic heart valve disease (RHVD) remain incompletely understood. Limited evidence suggests that abnormal DNA methylation might be involved in the pathogenesis of RHVD. In the present study, we evaluated the DNA methylation dysregulations from myocardial tissue in RHVD patients systematically.

Methods

Right atrial myocardial tissue obtained from rheumatic valvular patients who had undergone valve replacements surgery (n = 73) and were compared to healthy controls (n = 4). the promoter methylation level of Intercellular adhesion molecule-1 (ICAM-1) gene and its correlation with ICAM-1 mRNA expression level, the global DNA methylation level and its correlation with age and mRNA expression level of DNA methyltransferase (DNMT) genes were detected.

Results

The ICAM-1 mRNA expression was increased (healthy control vs. NHYA III, 0.70 ± 0.19 vs. 4.38 ± 3.19, p = 0.011; NYHA IIvs. NHYA III, 2.60 ± 1.99 vs. 4.38 ± 3.19, p = 0.008) and the ICAM-1 gene was hypomethylated in RHVD patients (healthy controls vs. NYHA II, 0.120 ± 0.011 vs. 0.076 ± 0.057, p = 0.039; healthy control vs. NHYA III, 0.120 ± 0.011 vs. 0.041 ± 0.022, p < 0.001; NYHA IIvs. NHYA III, 0.076 ± 0.057 vs. 0.041 ± 0.022, p < 0.001). Meanwhile, The ICAM-1 mRNA expression level has negative correlation with the mean methylation level in the promoter region of ICAM-1 gene (r = −0.459, p < 0.001). The global DNA methylation levels was significantly increased in RHVD patients than in healthy controls (healthy control vs. NHYA III, 0.77 ± 0.28 vs. 2.09 ± 1.20, p = 0.017; NYHA IIvs. NHYA III, 1.57 ± 0.78 vs. 2.09 ± 1.20, p = 0.040) and had positive correlation with age (r = 0.326, p = 0.005), especially for older age group (≥ 60 years). DNMT1 likely plays an essential role in the DNA dysregulations in RHVD patients.

Conclusions

Our analysis revealed that DNA methylation dysregulations may be relevant in the pathogenesis of RHVD.

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

BACKGROUND & OBJECTIVES

Rheumatic fever (RF) and rheumatic heart disease (RHD) are the autoimmune sequelae caused by Group A Streptococcus. RHD still remains a major concern in the developing countries due to its poor diagnosis, lack of vaccines and social awareness among population. This study was aimed to identify the plausible early- and late-stage disease markers associated with RF/RHD.

METHODS

A total of 84 patients with confirmed pharyngitis (n=18), RF (n=23) and RHD (n=43) were included in the comparative analysis of different factors involved in host-pathogen interaction during RF/RHD pathogenesis.

RESULTS

This study revealed high titre of serum antistreptolysin O (ASO) antibody in pharyngitis compared to RF and RHD patients, whereas procollagen type 1 C-peptide (PICP) level was elevated in RHD which showed an inverse correlation with serum ASO titre. The significant elevation of serum anti-peptide associated with RF (PARF) antibody in RF patients was correlated as a probable stage-specific determinant. In addition, pro-inflammatory cytokine profile revealed high levels of interleukin-12 (IL-12)/IL-23p40, IL-17A in RF, whereas IL-6 concentration was higher in RHD compared to healthy controls.

INTERPRETATION & CONCLUSIONS

The overall assessment of the factors/ disease markers involved in host-pathogen interaction in RF/RHD may be suggestive of plausible disease marker in different groups of patients. Further studies with larger sample need to be done to better understand RF/RHD pathogenesis.

Nano-Au/cMWCNT Modified speB Gene Specific Amperometric Sensor for Rapidly Detecting Streptococcus pyogenes causing Rheumatic Heart Disease

A specific 5' NH₂ labeled DNA probe of speB gene was immobilized onto the gold nanoparticles/carboxylated multi walled carbon nanotubes (Nano-Au/cMWCNT) screen printed electrode using EDC/NHS cross linking chemistry. This was followed by hybridization with 0.5-50 ng/6 µl of single stranded genomic DNA Streptococcus pyogenes infected patient throat swab samples. Electrochemical amperometric assay was deciphered by using cyclic voltammetry (CV) with methylene blue a redox indicator. The sensor had a sensitivity of 104.7 µA cm^-2 ng^-1 using CV with a R² of 0.907 and 0.01 ng/6 µl as the limit of detection (LOD). The modified electrode surface morphology was characterized using scanning electron microscopy. The stability of the electrode was seen at 4 °C for 180 days having 6% loss in the initial current. The sensor is speB gene specific and can detect the pathogen within 30 min.

Association of IL-4 (intron 3) and IL-10 (-1082) gene polymorphisms with risk of mitral valve disease in children with rheumatic heart disease

Aim Rheumatic heart disease is an inflammatory disease of cardiac tissue. The underlying pathogenic mechanisms highlight a complex interplay of immunological, genetic, and environmental factors. The aim of the present study was to investigate whether IL-4 (intron 3) and IL-10 (-1082) gene polymorphisms could be associated with susceptibility and/or severity of rheumatic heart disease among patients from the Egyptian population. Materials and methods A cohort of 140 Egyptian children with rheumatic heart disease and 100 healthy controls were enrolled in this case-control study. Genotyping for IL-4 (intron 3) and IL-10 (-1082) gene polymorphisms was carried out for all patients using a polymerase chain reaction-based analysis.

RESULTS

No significant difference in the distribution of genotypes and allelic frequencies between rheumatic heart disease cases and controls for IL-4 (intron 3) (p=0.17; OR 1.07, 95% CI 0.82-3.74) and IL-10 (-1082) (p=0.49; OR 1.03, 95% CI 0.65-2.71) gene polymorphisms was observed. Further categorisation of patients into mitral valve disease and combined valve disease subgroups showed that cases with mitral valve disease have significantly higher frequency of the RP2 allele of IL-4 (intron 3) (p=0.03; OR 2.98, 95% CI 1.93-6.15) and the G allele of IL-10 (-1082) (p=0.04; OR 2.14, 95% CI 1.62-4.95) when compared with controls. Discussion Our study shows that IL-4 (intron 3) and IL-10 (-1082) gene polymorphisms are not significantly associated with susceptibility to rheumatic heart disease, but they might play a role in the pathogenesis of patients with mitral valve disease.

Gene Specific Impedimetric Bacterial DNA Sensor for Rheumatic Heart Disease

An impedimetric mga gene specific DNA sensor was developed by immobilization of single stranded DNA probe onto the screen printed modified gold-dendrimer nanohybrid composite electrode for early and rapid detection of S. pyogenes in human throat swab samples causing rheumatic heart disease. Electrochemical impedance response was measured after hybridization with bacterial single stranded genomic DNA (ssG-DNA) with probe. The sensor was found highly specific to S. pyogenes and can detect as low as 0.01 ng ssDNA in 6 µL sample only in 30 min. The nanohybrid sensor was also tested with non-specific pathogens and characterized by FTIR. An early detection of the pathogen S. pyogenes in human can save damage of mitral and aortic heart valves (rheumatic heart disease) by proper medical care.

Brief Report: Prevalence of Latent Rheumatic Heart Disease Among HIV-Infected Children in Kampala, Uganda

Rheumatic heart disease (RHD) remains highly prevalent in resource-constrained settings around the world, including countries with high rates of HIV/AIDS. Although both are immune-mediated diseases, it is unknown whether HIV modifies the risk or progression of RHD. We performed screening echocardiography to determine the prevalence of latent RHD in 488 HIV-infected children aged 5-18 in Kampala, Uganda. The overall prevalence of borderline/definite RHD was 0.82% (95% confidence interval: 0.26% to 2.23%), which is lower than the published prevalence rates of 1.5%-4% among Ugandan children. There may be protective factors that decrease the risk of RHD in HIV-infected children.

Serum Levels of IL-17 and IL-23 in Patients With Rheumatic Mitral Stenosis

Rheumatic mitral valve stenosis (RMS) is a complication of rheumatic heart disease (RHD) and leads to significant morbidity and mortality. RHD is a chronic inflammatory and autoimmune disease that is associated with cytokine activities. The etiology of RMS is not fully understood yet. Interleukin (IL)-17 and IL-23 have a key role in development of the autoimmunity. The expression of these cytokines in RMS remains unclear. In this study, we investigated the serum levels of IL-17 and IL-23 in RMS patients compared to healthy subjects.A total of 35 patients admitted to cardiology outpatient clinic between December 2014 and May 2015 who were diagnosed with RMS formed the study group. Age- and gender-matched 35 healthy subjects were included as the control group. Statistical analyses were performed using SPSS 18.0 and P value <0.05 was considered as statistically significant.The patients with RMS had higher WBC count, hsCRP, systolic pulmonary artery pressure (PAPs), left atrial diameter (LAD), IL-17, and IL-23 levels compared to the control subjects. The levels of IL-17 (P = 0.012) and IL-23 (P = 0.004) were significantly higher in the RMS group. Correlation analysis revealed that IL-17 and IL-23 levels had a significant correlation with each other and with hsCRP and LAD.We demonstrated that serum levels of IL-17 and IL-23 are significantly higher in patients with RMS compared to those of healthy subjects. IL-17 and IL-23 expression may have a possible role in inflammatory processes that result in RMS development.

Rheumatic heart disease in Africa: is there a role for genetic studies?

Rheumatic heart disease (RHD) constitutes a leading cause of premature death and incapacity in Africa, where it is encountered in younger people, and shows a much faster and more malignant course than that seen in Europe or North America. While it is well established that RHD is a consequence of recurrent, untreated group A β-haemolytic streptococcal infections (GAS), the pathogenesis is incompletely understood, and the variation in natural history and phenotypes are not fully explained. In Africa patients are rarely diagnosed with acute rheumatic fever (ARF). They usually present in the late stages of RHD, with the severe and virulent forms occurring at early ages, therefore leading to high morbidity and mortality in young patients.

Revision of the Jones Criteria for the diagnosis of acute rheumatic fever in the era of Doppler echocardiography: a scientific statement from the American Heart Association

BACKGROUND

Acute rheumatic fever remains a serious healthcare concern for the majority of the world's population despite its decline in incidence in Europe and North America. The goal of this statement was to review the historic Jones criteria used to diagnose acute rheumatic fever in the context of the current epidemiology of the disease and to update those criteria to also take into account recent evidence supporting the use of Doppler echocardiography in the diagnosis of carditis as a major manifestation of acute rheumatic fever.

METHODS AND RESULTS

To achieve this goal, the American Heart Association's Council on Cardiovascular Disease in the Young and its Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee organized a writing group to comprehensively review and evaluate the impact of population-specific differences in acute rheumatic fever presentation and changes in presentation that can result from the now worldwide availability of nonsteroidal anti-inflammatory drugs. In addition, a methodological assessment of the numerous published studies that support the use of Doppler echocardiography as a means to diagnose cardiac involvement in acute rheumatic fever, even when overt clinical findings are not apparent, was undertaken to determine the evidence basis for defining subclinical carditis and including it as a major criterion of the Jones criteria. This effort has resulted in the first substantial revision to the Jones criteria by the American Heart Association since 1992 and the first application of the Classification of Recommendations and Levels of Evidence categories developed by the American College of Cardiology/American Heart Association to the Jones criteria.

CONCLUSIONS

This revision of the Jones criteria now brings them into closer alignment with other international guidelines for the diagnosis of acute rheumatic fever by defining high-risk populations, recognizing variability in clinical presentation in these high-risk populations, and including Doppler echocardiography as a tool to diagnose cardiac involvement.

Angiotensin-converting enzyme gene insertion/deletion polymorphism in Saudi patients with rheumatic heart disease

OBJECTIVES

To investigate the association between angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism and rheumatic heart disease (RHD) in Saudi patients.

METHODS

A case-control study was conducted in Saudi RHD patients. Genomic DNA was isolated from 99 RHD patients attending the Pediatric Cardiology Clinic at the Maternity and Children Hospital, Al-Madinah, Saudi Arabia from March 2013 to June 2014, and from 145 age- and gender-matched controls. Patient clinical records were reviewed to report major and minor modified Jones' criteria for diagnosis. The diagnosis was confirmed by echocardiography. The ACE I/D polymorphism was identified by polymerase chain reaction.

RESULTS

A significant difference in ACE D allele carriage (DD+ID) distribution between RHD cases and controls was identified (p=0.02, odds ratio = 3.6, 95% confidence interval: 1.2-10.8). The D allele carriage was significantly associated with development of mitral valve lesions alone (p=0.03).

CONCLUSION

The ACE I/D polymorphism is associated with an increased risk of RHD in the Saudi population. Further studies are needed to confirm our findings and to understand the molecular mechanisms underlying this association.

A case of rheumatic valvular heart disease and autoimmune gastritis

We present a case of a 50-year-old female patient with a history of depressive disorder and anaemia (attributed to menorrhagias). She was admitted to the cardiology department with symptoms of fatigue on moderate exertion for several months, with worsening in the month before hospitalisation. Echocardiography revealed a severe mitral stenosis of rheumatic aetiology. Laboratory tests showed microcytic and hypochromic anaemia, reduced iron stores and vitamin B12 levels, and positive serum antiparietal cells autoantibodies. Endoscopy showed focal areas of erythema in the stomach, corresponding histologically to chronic atrophic gastritis. In this context, two distinct clinical entities were diagnosed in the same patient: severe rheumatic mitral stenosis and autoimmune gastritis. The patient was started on vitamin B12 and iron supplementation and underwent surgical correction of the valvular disease. There was symptomatic improvement in her signs of fatigue.

Unresolved issues in theories of autoimmune disease using myocarditis as a framework

Many theories of autoimmune disease have been proposed since the discovery that the immune system can attack the body. These theories include the hidden or cryptic antigen theory, modified antigen theory, T cell bypass, T cell-B cell mismatch, epitope spread or drift, the bystander effect, molecular mimicry, anti-idiotype theory, antigenic complementarity, and dual-affinity T cell receptors. We critically review these theories and relevant mathematical models as they apply to autoimmune myocarditis. All theories share the common assumption that autoimmune diseases are triggered by environmental factors such as infections or chemical exposure. Most, but not all, theories and mathematical models are unifactorial assuming single-agent causation of disease. Experimental and clinical evidence and mathematical models exist to support some aspects of most theories, but evidence/models that support one theory almost invariably supports other theories as well. More importantly, every theory (and every model) lacks the ability to account for some key autoimmune disease phenomena such as the fundamental roles of innate immunity, sex differences in disease susceptibility, the necessity for adjuvants in experimental animal models, and the often paradoxical effect of exposure timing and dose on disease induction. We argue that a more comprehensive and integrated theory of autoimmunity associated with new mathematical models is needed and suggest specific experimental and clinical tests for each major theory that might help to clarify how they relate to clinical disease and reveal how theories are related.

Distinct mitral valve proteomic profiles in rheumatic heart disease and myxomatous degeneration

Rheumatic heart disease (RHD) affects heart-valve tissue and is the most serious consequence of group A Streptococcus infection. Myxomatous degeneration (MXD) is the most frequent valvopathy in the western world. In the present work, key protein expression alterations in the heart-valve tissue of RHD and MXD patients were identified and characterized, with controls from cadaveric organ donors. Proteins were separated by two-dimensional (2D)-electrophoresis and identified by mass spectrometry. We found 17 differentially expressed protein spots, as compared to control samples. We observed an increased expression of ASAP-2 in the RHD patients’ valves, while collagen-VI, haptoglobin-related protein, prolargin, and cartilage oligomeric protein showed reduced expression. Valve tissue of MXD patients, on the other hand, presented lower expression of annexin-A1 and A2, septin-2, SOD (Cu/Zn), and transgelin. Tissue samples from both valvopathies displayed higher expression of apolipoprotein-A1. Biglycan was downexpressed in both diseases. Vimentin and lumican showed higher expression in RHD and lower in MXD. These results suggest that key pathogenetic mechanisms are intrinsically distinct in RHD and MXD.

Clinical significance of markers of collagen metabolism in rheumatic mitral valve disease

BACKGROUND

Rheumatic Heart Disease (RHD), a chronic acquired heart disorder results from Acute Rheumatic Fever. It is a major public health concern in developing countries. In RHD, mostly the valves get affected. The present study investigated whether extracellular matrix remodelling in rheumatic valve leads to altered levels of collagen metabolism markers and if such markers can be clinically used to diagnose or monitor disease progression.

METHODOLOGY

This is a case control study comprising 118 subjects. It included 77 cases and 41 healthy controls. Cases were classified into two groups- Mitral Stenosis (MS) and Mitral Regurgitation (MR). Carboxy-terminal propeptide of type I procollagen (PICP), amino-terminal propeptide of type III procollagen (PIIINP), total Matrix Metalloproteinase-1(MMP-1) and Tissue Inhibitor of Metalloproteinase-1 (TIMP-1) were assessed. Histopathology studies were performed on excised mitral valve leaflets. A p value <0.05 was considered statistically significant.

RESULTS

Plasma PICP and PIIINP concentrations increased significantly (p<0.01) in MS and MR subjects compared to controls but decreased gradually over a one year period post mitral valve replacement (p<0.05). In MS, PICP level and MMP-1/TIMP-1 ratio strongly correlated with mitral valve area (r = -0.40; r = 0.49 respectively) and pulmonary artery systolic pressure (r = 0.49; r = -0.49 respectively); while in MR they correlated with left ventricular internal diastolic (r = 0.68; r = -0.48 respectively) and systolic diameters (r = 0.65; r = -0.55 respectively). Receiver operating characteristic curve analysis established PICP as a better marker (AUC = 0.95; 95% CI = 0.91-0.99; p<0.0001). A cut-off >459 ng/mL for PICP provided 91% sensitivity, 90% specificity and a likelihood ratio of 9 in diagnosing RHD. Histopathology analysis revealed inflammation, scarring, neovascularisation and extensive leaflet fibrosis in diseased mitral valve.

CONCLUSIONS

Levels of collagen metabolism markers correlated with echocardiographic parameters for RHD diagnosis.

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.

Analysis of the coverage capacity of the StreptInCor candidate vaccine against Streptococcus pyogenes

Streptococcus pyogenes is responsible for infections as pharyngitis, sepsis, necrotizing fasciitis and streptococcal toxic shock syndrome. The M protein is the major bacterial antigen and consists of both polymorphic N-terminal portion and a conserved region. In the present study, we analyzed the in vitro ability of StreptInCor a C-terminal candidate vaccine against S. pyogenes to induce antibodies to neutralize/opsonize the most common S. pyogenes strains in Sao Paulo by examining the recognition by sera from StreptInCor immunized mice. We also evaluated the presence of cross-reactive antibodies against human heart valve tissue. Anti-StreptInCor antibodies were able to neutralize/opsonize at least 5 strains, showing that immunization with StreptInCor is effective against several S. pyogenes strains and can prevent infection and subsequent sequelae without causing autoimmune reactions.

StreptInCor: a candidate vaccine epitope against S. pyogenes infections induces protection in outbred mice

Infection with Streptococcus pyogenes (S. pyogenes) can result in several diseases, particularly in children. S. pyogenes M protein is the major virulence factor, and certain regions of its N-terminus can trigger autoimmune sequelae such as rheumatic fever in susceptible individuals with untreated group A streptococcal pharyngitis. In a previous study, we utilized a large panel of human peripheral blood cells to define the C-terminal protective epitope StreptInCor (medical identity), which does not induce autoimmune reactions. We recently confirmed the results in HLA-transgenic mice. In the present study, we extended the experimental assays to outbred animals (Swiss mice). Herein, we demonstrate high titers of StreptInCor-specific antibodies, as well as appropriate T-cell immune responses. No cross-reaction to cardiac myosin was detected. Additionally, immunized Swiss mice exhibited 87% survival one month after challenge with S. pyogenes. In conclusion, the data presented herein reinforce previous results in humans and animals and further emphasize that StreptInCor could be an effective and safe vaccine for the prevention of S. pyogenes infections.

The management of subacute bacterial endocarditis superimposed on rheumatic heart disease in the immediate pre-penicillin era: the case of Pasquale Imperato

Subacute bacterial endocarditis (SBE) was invariably a fatal disease in the pre-penicillin era. The availability of sulfonamide antibiotics beginning in the mid-1930s raised hopes that they would be effective in SBE. Unfortunately, except in rare instances, they were not. This paper reviews the clinical experience with sulfonamides in the pre-penicillin period in treating patients with SBE. It presents in detail the case of Pasquale Imperato, who died from the disease at the age of 72 years on 30 November 1942. In so doing, it focuses on the medical management measures then available to treat patients with SBE and on the inevitable course of the illness once it began. Also discussed is the relationship of acute rheumatic fever and its sequela, rheumatic heart disease, to predisposing people to SBE and possible genetic factors. The well-known case of Alfred S. Reinhart, a Harvard Medical School student who died from SBE in 1931 and who kept a detailed chronicle of his disease, is also discussed and contrasted with Pasquale Imperato's case.