Rheumatic fever and rheumatic heart disease: cellular mechanisms leading autoimmune reactivity and disease

Acute rheumatic fever and Post-streptococcal reactive arthritis

Acute rheumatic fever (ARF) and poststreptococcal reactive arthritis (PSRA) represent two distinct but related poststreptococcal conditions, both arising from an autoimmune response following Group A streptococcal (GAS) infection, typically pharyngitis. Although both illnesses have a shared trigger, their clinical presentations and long-term consequences differ markedly. ARF, a systemic inflammatory disorder, can impact several organs, particularly the heart, potentially resulting in chronic rheumatic heart disease with irreversible valve damage. The cornerstone of ARF treatment includes Streptococcus eradication therapy, symptom management, and secondary prophylaxis to prevent recurrence. In contrast, PSRA primarily presents as non-infectious, nonmigratory, persistent arthritis without carditis and generally resolves without lasting sequelae. Distinguishing PSRA from ARF is crucial for appropriate management and to avoid unnecessary long-term antibiotic prophylaxis. This review focuses on the key clinical features and diagnostic approaches for ARF and PSRA, along with an overview of their management strategies.

A mini review of the pathogenesis of acute rheumatic fever and rheumatic heart disease

Acute rheumatic fever (ARF) is an autoimmune disease caused by group A streptococcal infection. Recurrent episodes of ARF can lead to rheumatic heart disease (RHD), which is the leading cause of cardiovascular mortality in children worldwide, especially in low- and middle-income countries. Investigations into the etiology of ARF and RHD constitute a crucial milestone in the advancement of both preventive measures and therapeutic interventions. The purpose of this mini review is to delineate the etiology and pathophysiological mechanisms underlying ARF and RHD. Selective searches were conducted in PubMed to retrieve literature published between 1968 and 2024, employing key terms such as "acute rheumatic fever", "rheumatic heart disease", "group A Streptococcus", "streptococcal pharyngitis", "pathogenesis", and "pathophysiology". The pathogenesis of infections caused by group A streptococci, and their effects on ARF and RHD, have been thoroughly examined. A central hypothesis is that autoimmune responses are triggered by molecular mimicry, but alternate pathogenic mechanisms are continuously being explored. There is an urgent need for high-quality research that can inform efforts aimed at decreasing the occurrence of ARF and halting the advancement of RHD, which requires researchers to understand its causes and to develop appropriate preventive and therapeutic programs.

Age Differences in Aortic Stenosis

Aortic stenosis (AS) is a significant and growing concern, with a prevalence of 2-3% in individuals aged over 65 years. Moreover, with an aging global population, the prevalence is anticipated to double by 2050. Indeed, AS can arise from various etiologies, including calcific trileaflets, congenital valve abnormalities (e.g., bicuspid and unicuspid valves), and post-rheumatic, whereby each has a distinct influence that shapes the onset and progression of the disease. The normal aortic valve has a trilaminar structure comprising the fibrosa, spongiosa, and ventricularis, which work together to maintain its function. In calcific AS, the disease begins with early calcification starting in high mechanical stress areas of the valve and progresses slowly over decades, eventually leading to extensive calcification resulting in impaired valve function. This process involves mechanisms similar to atherosclerosis, including lipid deposition, chronic inflammation, and mineralization. The progression of calcific AS is strongly associated with aging, with additional risk factors including male gender, smoking, dyslipidemia, and metabolic syndrome exacerbating the condition. Conversely, congenital forms of AS, such as bicuspid and unicuspid aortic valves, result in an earlier disease onset, typically 10-20 years earlier than that observed in patients with a normal tricuspid aortic valve. Rheumatic AS, although less common in developed countries due to effective antibiotic treatments, also exhibits age-related characteristics, with an earlier onset in individuals who experienced rheumatic fever in their youth. The only curative therapies currently available are surgical and transcatheter aortic valve replacement (TAVR). However, these options are sometimes too invasive for older patients; thus, management of AS, particularly in older patients, requires a comprehensive approach that considers age, disease severity, comorbidities, frailty, and each patient's individual needs. Although the valves used in TAVR demonstrate promising midterm durability, long-term data are still required, especially when used in younger individuals, usually with low surgical risk. Moreover, understanding the causes and mechanisms of structural valve deterioration is crucial for appropriate treatment selections, including valve selection and pharmacological therapy, since this knowledge is essential for optimizing the lifelong management of AS.

Transcatheter Therapy for Mitral Valve Stenosis

Mitral valve stenosis remains highly prevalent among the US population although with dramatically shifting demographics. The significance of rheumatic mitral disease in developing nations persists, despite improvements in preventative measures and early detection, and its presence in developed countries is still evident as observed through international migration. In addition, the substantial growth in the aging population with a heightened occurrence of concurrent cardiovascular risk factors is leading to an increased prevalence of chronic calcific degeneration and degeneration of previously repaired or replaced valves. This article aims to review various transcatheter therapies in the treatment of mitral valve stenosis.

Inflammatory Response Genes' Polymorphism Associated with Risk of Rheumatic Heart Disease

Rheumatic heart disease (RHD) caused by group A streptococcus infection is one of the most important reasons of cardiovascular morbidity and mortality in low- and middle-income countries. Aberrant host immune response modulated by polymorphisms in inflammatory response genes plays an important role in RHD pathogenesis. This study aimed to determine risk-associated polymorphic variants in inflammatory response genes in Caucasian RHD patients. A total of 251 Caucasian RHD patients and 300 healthy donors were recruited for this study, and 27 polymorphic sites in 12 genes (TLR1, TLR2, TLR4, TLR6, IL1B, IL6R, IL6, IL10, IL12RB1, IL12B, TNF and CRP) were analyzed using allele-specific PCR. It was demonstrated that the polymorphic variants rs1800871 and rs1800872 in the IL10 gene, rs 1130864, rs3093077 and rs1205 in the CRP gene, rs375947 in the IL12RB1 gene, rs 5743551 and rs5743611 in the TLR1 gene, and rs3775073 in the TLR6 gene can modify RHD risk in a gender- and age-dependent manner. The obtained results can be used to determine the personalized risk of RHD in healthy donors during medical examination or screening, as well as to develop appropriate early prevention strategies targeting RHD in the risk groups.

Engineering antigen-presenting cells for immunotherapy of autoimmunity

Autoimmune diseases are burdensome conditions that affect a significant fraction of the global population. The hallmark of autoimmune disease is a host's immune system being licensed to attack its tissues based on specific antigens. There are no cures for autoimmune diseases. The current clinical standard for treating autoimmune diseases is the administration of immunosuppressants, which weaken the immune system and reduce auto-inflammatory responses. However, people living with autoimmune diseases are subject to toxicity, fail to mount a sufficient immune response to protect against pathogens, and are more likely to develop infections. Therefore, there is a concerted effort to develop more effective means of targeting immunomodulatory therapies to antigen-presenting cells, which are involved in modulating the immune responses to specific antigens. In this review, we highlight approaches that are currently in development to target antigen-presenting cells and improve therapeutic outcomes in autoimmune diseases.

Transcatheter Therapy for Mitral Valve Stenosis

Mitral valve stenosis remains highly prevalent among the US population although with dramatically shifting demographics. The significance of rheumatic mitral disease in developing nations persists, despite improvements in preventative measures and early detection, and its presence in developed countries is still evident as observed through international migration. In addition, the substantial growth in the aging population with a heightened occurrence of concurrent cardiovascular risk factors is leading to an increased prevalence of chronic calcific degeneration and degeneration of previously repaired or replaced valves. This article aims to review various transcatheter therapies in the treatment of mitral valve stenosis.

[Rheumatic cardiopathies and its risk factors: about 50 cases]

INTRODUCTION

Acute rheumatic fever (ARF) is a multi-systemic disease, in which cardiac involvement is the most serious major manifestation of disease. The aim of this study was to analyse cardiac involvement in children with ARF and his risk factors.

MATERIALS AND METHODS

It were a retrospective study including all children under the age of 14 years who were hospitalized for ARF in the pediatric department of the CHU Hédi Chaker of Sfax, during a period of twelve years (2010-2022).

RESULTS

We collected 50 cases (31 boys and 19 girls). Twenty-two patients (44%) developed cardiac lesions. The mean age at diagnosis was 9.6 years [5-14 years]. A pathological heart murmur was detected in 14 cases (n = 14/22) was classified as mild carditis in 15 cases, moderate carditis in 5 cases and severe in 2 cases. The median follow-up time was 3,3 years. Nineteen patients developed valvular sequelae Risk factors of cardiac lesions was: age more than 8 years, heart murmur, allonged PR, CRP > 100 mg/l and VS > 100 mm.

CONCLUSION

CR is still a public health problem in Tunisia. It is a serious pathology that can cause serious increases in morbidity rates. Thus, we must strengthen preventive strategies.

The good and the bad of T cell cross-reactivity: challenges and opportunities for novel therapeutics in autoimmunity and cancer

T cells are main actors of the immune system with an essential role in protection against pathogens and cancer. The molecular key event involved in this absolutely central task is the interaction of membrane-bound specific T cell receptors with peptide-MHC complexes which initiates T cell priming, activation and recall, and thus controls a range of downstream functions. While textbooks teach us that the repertoire of mature T cells is highly diverse, it is clear that this diversity cannot possibly cover all potential foreign peptides that might be encountered during life. TCR cross-reactivity, i.e. the ability of a single TCR to recognise different peptides, offers the best solution to this biological challenge. Reports have shown that indeed, TCR cross-reactivity is surprisingly high. Hence, the T cell dilemma is the following: be as specific as possible to target foreign danger and spare self, while being able to react to a large spectrum of body-threatening situations. This has major consequences for both autoimmune diseases and cancer, and significant implications for the development of T cell-based therapies. In this review, we will present essential experimental evidence of T cell cross-reactivity, implications for two opposite immune conditions, i.e. autoimmunity vs cancer, and how this can be differently exploited for immunotherapy approaches. Finally, we will discuss the tools available for predicting cross-reactivity and how improvements in this field might boost translational approaches.

Pertussis toxin-induced inhibition of Wnt/β-catenin signaling in dendritic cells promotes an autoimmune response in experimental autoimmune uveitis

BACKGROUND

Previous reports have indicated that disrupting the Wnt/β-catenin pathway in dendritic cells (DCs) may affect the progression of autoimmune inflammation; however, the factors and timing that regulate Wnt/β-catenin signaling have not been clearly understood.

METHODS

Experimental autoimmune uveitis (EAU) mice and Vogt-Koyanagi-Harada disease (VKH) patient samples were used to detect the expression of Wnt/β-catenin pathway genes. Western blot, real-time PCR, flow cytometry, and ELISA were performed to examine the expression of components of the Wnt/β-catenin pathway and inflammatory factors. DC-specific β-catenin knockout mice and 6-bromoindirubin-3'-oxime (BIO) administered mice were used to observe the effect of disrupting the Wnt pathway on EAU pathogenesis.

RESULTS

Wnt/β-catenin signaling was inhibited in DCs during the induction phase of EAU. The inhibition was mediated by pertussis toxin (PTX), which promoted DC maturation, in turn promoting pathogenic T cell proliferation and differentiation. In vivo experiments confirmed that deleting β-catenin in DCs enhanced EAU severity, and pre-injection of PTX advanced EAU onset. Administration of a Wnt activator (BIO) limited the effects of PTX, in turn ameliorating EAU.

CONCLUSIONS

Our results demonstrate that PTX plays a key role as a virulence factor in initiating autoimmune inflammation via DCs by inhibiting Wnt/β-catenin signaling in EAU, and highlight the potential mechanism by which infection can trigger apparent autoimmunity.

The Role of Inflammation and Oxidative Stress in Rheumatic Heart Disease

Rheumatic heart disease (RHD), an acquired valvular disease, remains an important cause of morbidity and mortality in developing countries. This chronic illness starts from untreated streptococcal throat infection, resulting in acute rheumatic fever (ARF) in susceptible individuals. Repeated infections lead to a chronic phase characterized by the damage of heart valves. Inflammation has been found to play important role in the development of this disease. All the studies presented in this review clearly show the involvement of the inflammatory state in the progression of this disease. However, the exact role of cytokines in inflammation sites remains to be examined, since most studies have so far focused on peripheral blood. Such analysis would provide information on inflammatory mechanisms in situ.

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.

Pentraxin 3 levels and correlation with disease severity in patients with acute rheumatic fever

Objectives

This study aims to investigate serum pentraxin 3 (PTX3) levels during acute episode of acute rheumatic fever (ARF) and their relationship with disease severity.

Patients and methods

The prospective study was conducted between January 2015 and December 2018 and included 52 ARF patients (22 girls, 30 boys, mean age 10.7±2.1 years; range, 5 to 16 years) experiencing an acute episode and 22 healthy children (13 girls, 9 boys, mean age 10.3±3.8 years; range, 5 to 16 years). ARF patients were classified into three groups based on the clinical course: isolated arthritis (n=17), mild carditis (n=19), and moderate/severe carditis (n=16). Blood samples were collected from all patients before treatment and from the healthy children in the control group to measure PTX3 levels. PTX3 was measured using sandwich enzyme-linked immunosorbent assay method.

Results

Plasma PTX3 levels were significantly higher in ARF group compared to the control group (4.7±5.2 and 1.2±1.7 ng/mL, p<0.001). Subgroup analysis of serum PTX3 levels in ARF patients with isolated arthritis, mild carditis, and moderate/severe carditis (3.2±3.1 ng/mL, 4.3±5 ng/mL, and 6.7±6.6 ng/mL, respectively) showed that serum PTX3 was significantly higher in the moderate/severe carditis group compared to the other groups (p<0.05). Analysis of echocardiographic data showed that serum PTX3 was positively correlated with left ventricular end-diastolic diameter, left atrial diameters, and mitral A velocity and negatively correlated with E/A ratio (p<0.05; r=0.231, 0.402, 0.562, -0.586, respectively).

Conclusion

High PTX3 level during an acute episode of ARF may help predict the clinical course and the severity of accompanying carditis. However, prospective studies with larger sample sizes are needed.

Cardiac Immunology: A New Era for Immune Cells in the Heart

The immune system is essential for the development and homeostasis of the human body. Our current understanding of the immune system on disease pathogenesis has drastically expanded over the last decade with the definition of additional non-canonical roles in various tissues. Recently, tissue-resident immune cells have become an important research topic for understanding their roles in the prevention, pathogenesis, and recovery from the diseases. Heart resident immune cells, particularly macrophage subtypes, and their characteristic morphology, distribution in the cardiac tissue, and transcriptional profile have been recently reported in the experimental animal models, unrevealing novel and unexpected roles in electrophysiological regulation of the heart both at the steady-state and diseased state. Immunological processes have been widely studied in both sterile cardiac disorders, such as myocardial infarction, autoimmune cardiac diseases, or infectious cardiac diseases, such as myocarditis, endocarditis, and acute rheumatic carditis. Following cardiac injury, innate and adaptive immunity have critical roles in pro- and anti-inflammatory processes. Heart resident immune cells not only provide defense against infectious diseases but also contribute to the homeostasis. In recent years, physiological changes and pathological processes were demonstrated to alter the abundance, distribution, polarization, and diversity of immune cells in the heart. Accumulating evidence indicates that cardiac remodeling is controlled by the complex crosstalk between cardiomyocytes and cardiac immune cells through the gap junctions, providing the ion flow to achieve synchronization and modulation of contractility. This review article aims to review the well-documented roles of both resident and recruited immune cell in the heart, as well as their recently uncovered unconventional roles in both cardiac homeostasis and cardiovascular diseases. We have mostly focused on studies on animal models used in preclinical research, underlying the need for further investigations in humans or in vitro human models. It may be foreseen that the further comprehensive investigations of cardiac immunology might harbor new therapeutic options for cardiac disorders that have tremendous medical potential.

Site-Specific Conjugation of Cell Wall Polyrhamnose to Protein SpyAD Envisioning a Safe Universal Group A Streptococcal Vaccine

Development of an effective vaccine against the leading human bacterial pathogen group A Streptococcus (GAS) is a public health priority. The species defining group A cell wall carbohydrate (GAC, Lancefield antigen) can be engineered to remove its immunodominant N-acetylglucosamine (GlcNAc) side chain, implicated in provoking autoimmune cross-reactivity in rheumatic heart disease, leaving its polyrhamnose core (GACPR). Here we generate a novel protein conjugate of the GACPR and test the utility of this conjugate antigen in active immunization. Instead of conjugation to a standard carrier protein, we selected SpyAD, a highly conserved GAS surface protein containing both B-cell and T-cell epitopes relevant to the bacterium that itself shows promise as a vaccine antigen. SpyAD was synthesized using the XpressTM cell-free protein expression system, incorporating a non-natural amino acid to which GACPR was conjugated by site-specific click chemistry to yield high molecular mass SpyAD-GACPR conjugates and avoid disruption of important T-cell and B-cell immunological epitopes. The conjugated SpyAD-GACPR elicited antibodies that bound the surface of multiple GAS strains of diverse M types and promoted opsonophagocytic killing by human neutrophils. Active immunization of mice with a multivalent vaccine consisting of SpyAD-GACPR, together with candidate vaccine antigens streptolysin O and C5a peptidase, protected against GAS challenge in a systemic infection model and localized skin infection model, without evidence of cross reactivity to human heart or brain tissue epitopes. This general approach may allow GAC to be safely and effectively included in future GAS subunit vaccine formulations with the goal of broad protection without autoreactivity.

Histopathological Characterization of Mitral Valvular Lesions from Patients with Rheumatic Heart Disease

BACKGROUND

The underlying mechanisms by which rheumatic heart disease (RHD) lead to severe valve dysfunction are not completely understood.

OBJECTIVE

The present study evaluated the histopathological changes in mitral valves (MV) seeking an association between the pattern of predominant valvular dysfunction and histopathological findings.

METHODS

In 40 patients who underwent MV replacement due to RHD, and in 20 controls that underwent heart transplant, histological aspects of the excised MV were analyzed. Clinical and echocardiographic data were also collected. Histological analyses were performed using hematoxylin-eosin staining. Inflammation, fibrosis, neoangiogenesis, calcification and adipose metaplasia were determined. A p value<0.05 was considered to be statistically significant.

RESULTS

The mean age of RHD patients was 53±13 years, 36 (90%) were female, whereas the mean age of controls was 50±12 years, similar to the cases, with the majority of males (70%). The rheumatic valve endocardium presented greater thickness than the controls (1.3±0.5 mm versus 0.90±0.4 mm, p=0.003, respectively), and a more intense inflammatory infiltrate in the endocardium (78% versus 36%; p=0.004), with predominance of mononuclear cells. Moderate to marked fibrosis occurred more frequently in rheumatic valves than in control valves (100% vs. 29%; p<0.001). Calcification occurred in 35% of rheumatic valves, especially among stenotic valves, which was associated with the mitral valve area (p=0.003).

CONCLUSIONS

Despite intense degree of fibrosis, the inflammatory process remains active in the rheumatic mitral valve, even at late disease with valve dysfunction. Calcification predominated in stenotic valves and in patients with right ventricular dysfunction.

Survey of actual conditions of erythema marginatum as a prodromal symptom in Japanese patients with hereditary angioedema

Background

Hereditary angioedema (HAE) is a rare but life-threatening condition. HAE types I and II (HAE-1/2) result from C1-inhibitor (C1–INH) deficiency. However, recent genetic analysis has established a new type of HAE with normal C1–INH (HAEnC1-INH). The mutations of factor XII, plasminogen, angiopoietin 1, and kininogen 1 genes may be the cause of HAEnC1-INH. Nevertheless, other causative molecules (HAE-unknown) may be involved. The Japanese therapeutic environment for HAE has been improving owing to the self-subcutaneous injection of icatibant, which was approved for the treatment of acute attack and enables early therapy. Erythema marginatum (EM) is a visible prodromal symptom which occasionally occurs prior to an angioedema attack; hence, recognizing the risk of an acute attack is important for early treatment. However, the detailed characteristics of EM remain unclear. In this study, we first investigated the clinical manifestations of EM in Japanese patients with HAE.

Methods

A 20-point survey was developed and distributed to 40 physicians to gather clinical data on EM from patients with HAE.

Results

Data on 68 patients with HAE (58 patients with HAE-1/2 and 10 patients with HAE-unknown) were collected. Of the patients with HAE-1/2, 53.4% experienced EM, whereas 43.1% did not. The forearm was the most frequent area of EM (64.5%), followed by the abdomen (29.0%) and upper arm and precordium (19.3%). Of the HAE-1/2 patients with EM, 41.9% always had angioedema following EM, while 29.0% always had colocalization of EM with angioedema. Moreover, 3.2% showed a correlation between the awareness of EM and severity of an angioedema attack. In 60.9% of HAE-1/2 patients with EM, the interval between the awareness of EM and appearance of angioedema was <3 h. Of the patients with HAE-unknown, 30.0% also experienced EM.

Conclusion

We confirmed that more than one-half of Japanese patients with HAE-1/2 and one-third of those with HAE-unknown develop EM as the prodromal symptom of an angioedema attack. Physicians should communicate the significance of EM to patients with HAE to prepare them for possible imminent attacks.

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.

Echocardiography Screening for Latent Rheumatic Heart Disease: What Can We Do in Indonesia?

Rheumatic heart disease (RHD), a sequela of acute rheumatic fever (ARF), is a preventable disease but remains a significant health problem, especially in developing countries. It causes disability, poor quality of life, early mortality, and national economic burden. The World Heart Federation (WHF) aimed to achieve a 25% reduction in premature deaths from ARF and RHD among individuals aged <25 years by 2025. Primordial and primary prophylaxis of RHD is aimed to prevent the occurrence of ARF, while the goal of secondary and tertiary prophylaxis is to limit the progression and reduce the consequences of RHD. Early recognition of RHD is important for early prophylaxis strategies to inhibit any progression to advanced stages. In 2012, WHF introduced the latest echocardiographic criteria to recognize the early stage of RHD. This includes the evaluation of pathological regurgitation jet and morphological features of RHD based on 2D, color, and spectral Doppler criteria. In remote areas, portable echocardiography is preferable for RHD screening. Previous portable devices were only capable of producing 2D and color images. Hence, a simplified echocardiographic criterion without spectral Doppler evaluation is needed in selected areas. Indonesia is a developing country, an archipelago with a population of over 250 million. Currently, there are no data on ARF incidence and RHD prevalence nationwide. The only data available are the number of patients in advanced stages who came to referral centers for further management. The screening program has to be introduced in Indonesia as part of national RHD prophylaxis.

Pediatric Inflammatory Multisystem Syndrome Temporally Related With SARS-CoV-2: Immunological Similarities With Acute Rheumatic Fever and Toxic Shock Syndrome

Several studies demonstrated that COVID-19 in children is a relatively mild disease. However, recently a more serious condition characterized by systemic inflammation with clinical or microbiological evidence of exposure to SARS-CoV-2 has been described. This syndrome is now known as either "Pediatric Inflammatory Multisystem Syndrome temporally related with COVID-19" (PIMS-TS) (1), or Multisystem Inflammatory Syndrome in Children (MIS-C) (2) and is currently considered a rare post-COVID-19 complication which, in a minority of cases, can lead to death. The signs and symptoms of PIMS-TS are largely overlapping with the for Kawasaki disease (KD) and toxic shock syndrome (TSS) and are characterized, by fever, systemic inflammation, abdominal pain and cardiac involvement. In this study, we describe clinical and immunological characteristics shared by PIMS-TS, acute rheumatic fever and TSS, in order to provide hypotheses to direct future clinical and basic research studies.

Evaluating Vitamin D levels in Rheumatic Heart Disease patients and matched controls: A case-control study from Nepal

Background

Diagnosis and treatment for Rheumatic Heart Disease (RHD) is inaccessible for many of the 33 million people in low and middle income countries living with this disease. More knowledge about risk factors and pathophysiologic mechanisms involved is needed in order to prevent disease and optimize treatment. This study investigated risk factors in a Nepalese population, with a special focus on Vitamin D deficiency because of its immunomodulatory effects.

Methods

Ninety-nine patients with confirmed RHD diagnosis and 97 matched, cardiac-healthy controls selected by echocardiography were recruited from hospitals in the Central and Western region of Nepal. Serum 25(OH)D concentrations were assessed using dried blood spots and anthropometric values measured to evaluate nutritional status. Conditional logistic regression analysis was used to define association between vitamin D deficiency and RHD.

Results

The mean age of RHD patients was 31 years (range 9–70) and for healthy controls 32 years (range 9–65), with a 4:1 female to male ratio. Vitamin D levels were lower than expected in both RDH and controls. RHD patients had lower vitamin D levels than controls with a mean s-25(OH)D concentration of 39 nmol/l (range 8.7–89.4) compared with controls 45 nmol/l (range 14.5–86.7) (p-value = 0.02). People with Vitamin D insufficiency had a higher risk (OR = 2.59; 95% CI: 1.04–6.50) of also having RHD compared to people with Vitamin D concentrations >50 nmol/l. Body mass index was significantly lower in RHD patients (22.6; 95% CI, 21.5–23.2) compared to controls (24.2; 95% CI, 23.3–25.1).

Conclusion

RHD patients in Nepal have lower Vitamin D levels and overall poor nutritional status compared to the non-RHD controls. Longitudinal studies are needed to explore the causality between RHD and vitamin D level. Future research is also recommended among Nepali general population to confirm the low level of vitamin D as reported in our control group.

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.

Mechanistic implications of altered protein expression in rheumatic heart disease

Rheumatic heart disease (RHD) is a major cause of cardiovascular morbidity and mortality in low- and middle-income countries, where living conditions promote spread of group A β-haemolytic streptococcus. Autoimmune reactions due to molecular mimicry of bacterial epitopes by host proteins cause acute rheumatic fever (ARF) and subsequent disease progression to RHD. Despite knowledge of the factors that predispose to ARF and RHD, determinants of the progression to valvular damage and the molecular events involved remain incompletely characterised. This review focuses on altered protein expression in heart valves, myocardial tissue and plasma of patients with RHD and pathogenic consequences on RHD. Proteins mainly involved in structural organization of the valve matrix, blood homeostasis and immune response were altered due to RHD pathogenesis. Study of secreted forms of these proteins may aid the development of non-invasive biomarkers for early diagnosis and monitoring outcomes in RHD. Valve replacement surgery, the single evidence-based strategy to improve outcomes in severe RHD, is costly, largely unavailable in low- and middle-income countries (LMIC) and requires specialised facilities. When diagnosed early, penicillin prophylaxis may be used to delay progression to severe valvular damage. Echocardiography and cardiovascular magnetic resonance and the standard imaging tools recommended to confirm early diagnosis remain largely unavailable and inaccessible in most LMIC and both require expensive equipment and highly skilled persons for manipulation as well as interpretation of results. Changes in protein expression in heart valves and myocardium are associated with progressive valvular deformation in RHD. Understanding these protein changes should shed more light on the mechanisms of pathogenicity, while secreted forms of these proteins may provide leads towards a biomarker for non-invasive early detection of RHD.

Serum periostin levels in acute rheumatic fever: is it useful as a new biomarker?

Background: Acute rheumatic fever (ARF) continues to be a public health problem in low- and middle-income countries. Because there is no specific laboratory test for the exact diagnosis of ARF, the diagnosis is made by the modified Jones criteria. Periostin is an extracellular matrix protein which has been shown to be expressed during remodelling, mechanical stress and tissue repair. There are no data on the relationship between periostin and ARF.Aim: To evaluate serum periostin levels in patients with ARF and investigate its usefulness as a biomarker for diagnosing and monitoring the efficacy of treatment.Methods: Serum periostin levels were estimated in 31 patients with ARF and compared with a control group of 25 healthy patients. The control group comprised patients referred to the outpatient clinic for further evaluation of cardiac murmur, palpitations or chest pain. Patients who were diagnosed with any other cardiac or systemic illness after detailed systemic and cardiac examination were excluded.Results: The mean (SD) age at diagnosis was 12.1 (3.3) years in the patient group, 48.4% of whom were male. There were no significant differences in age or gender between patients and controls. All the study patients had various degrees of carditis, 58.1% had arthritis and 9.6% had Sydenham chorea. Mean (SD) serum periostin levels in patients with ARF on admission [58.4 (13.9) ng/mL] were significantly higher than in the control group [35.1 (10.7) ng/mL, p < 0.01] and were also significantly decreased in the patient group after treatment [35.1 (13.1) ng/mL, p < 0.01]. There was no significant difference in serum periostin levels regarding the severity of carditis in the patient group while patients with any severity of carditis had significantly higher periostin levels than the controls (p < 0.01). Periostin levels were significantly correlated with ESR and CRP values before treatment, but this correlation was detected for only ESR after treatment. For the initial diagnosis of ARF, a serum periostin level of 53.45 ng/mL was found to be the cut-off point with 80.6% sensitivity and 100% specificity.Conclusion: There was a significant increase in serum periostin levels in patients with ARF and a reduction after adequate treatment which was independent of the severity of carditis. Periostin may be a biomarker which acts as an acute phase reactant in ARF.

Rheumatic Fever and Rheumatic Heart Disease in Children

Acute rheumatic fever (ARF) and its sequelae, Rheumatic heart disease (RHD), contribute significantly to the cardiovascular morbidity and mortality in developing countries. Generally considered a disease of poverty and poor socio-economic conditions, RHD affects the population at the most productive phase of their life. The diagnostic criteria for ARF have been constantly updated to improve the sensitivity. The diagnosis of ARF was entirely clinical however, recently echocardiographic evidence has been added as a major criterion. The disease seems to be on the decline in India, but recent studies using echocardiography have shown high prevalence of RHD among school children. The focus of management has been on prompt recognition and treatment of streptococcal pharyngitis and preventing recurrences of ARF with long-term antibiotic prophylaxis. However, emphasis should be placed on the appropriate management of patients with established RHD, in order to limit the RHD related mortality.

Circulating follicular T helper cells and humoral reactivity in rheumatic heart disease

AIMS

This study aimed to profile circulating T follicular helper cells (cTfh) and their effect on B cells in rheumatic heart disease (RHD).

MATERIALS AND METHODS

Participants were divided into healthy control (HC, n = 30) and RHD (n = 30) groups. Percentages of cTfh subpopulations, based on CD4, CXCR5, CXCR3, CCR6, Foxp3, Ki67, and PD-1 cell markers, and of CD19⁺ B cell subgroups were measured by flow cytometry and compared between the groups. Also, IL-21 concentration in plasma and mitral valve were quantitated by cytometric bead array, immunofluorescence, and western blotting.

KEY FINDINGS

The PD-1⁺ cTfh, B cells (naive B cells, plasmablasts, and plasma B cells) proportion and cTfh17/cTfh ratios in RHD group were significantly increased, compared to HC (p < 0.01 in all cases), while different types of memory B cells were diminished (p < 0.001). In RHD patients, percentages of PD-1⁺ cTfh and switched memory B cells were negatively correlated (r = -0.565, p = 0.009); meanwhile, percentages of plasmablasts and PD-1⁺ cTfh cells were positively correlated (r = 0.594, p = 0.005). Additionally, IL-21 levels in plasma and mitral valve of RHD group were higher than those in HC. Also, IL-21 levels correlated with PD-1⁺ cTfh(r = 0.557, p = 0.010), cTfh17 (r = 0.567, p = 0.009), and plasmablast (r = -0.5957, p = 0.005) cell proportions, and (cTh2 + cTh17)/cTfh1 ratio (r = -0.547, p = 0.013).

SIGNIFICANCE

The activation of PD-1⁺ cTfh and cTfh17 subtype was highly correlated with plasmablast maturation and IL-21 production in rheumatic heart disease. Thus indicating the prominent role of cTfh and humoral reactivity in the immune pathogenesis of RHD.

Alterations in the Nervous System and Gut Microbiota after β-Hemolytic Streptococcus Group A Infection-Characteristics and Diagnostic Criteria of PANDAS Recognition

The objective of this paper is to review and summarize conclusions from the available literature regarding Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS). The authors have independently reviewed articles from 1977 onwards, primarily focusing on the etiopathology, symptoms, differentiation between similar psychiatric conditions, immunological reactions, alterations in the nervous system and gut microbiota, genetics, and the available treatment for PANDAS. Recent research indicates that PANDAS patients show noticeable alterations within the structures of the central nervous system, including caudate, putamen, globus pallidus, and striatum, as well as bilateral and lentiform nuclei. Likewise, the presence of autoantibodies that interact with basal ganglia was observed in PANDAS patients. Several studies also suggest a relationship between the presence of obsessive-compulsive disorders like PANDAS and alterations to the gut microbiota. Further, genetic predispositions-including variations in the MBL gene and TNF-α-seem to be relevant regarding PANDAS syndrome. Even though the literature is still scarce, the authors have attempted to provide a thorough insight into the PANDAS syndrome, bearing in mind the diagnostic difficulties of this condition.

p53 dynamics in single cells are temperature-sensitive

Cells need to preserve genome integrity despite varying cellular and physical states. p53, the guardian of the genome, plays a crucial role in the cellular response to DNA damage by triggering cell cycle arrest, apoptosis or senescence. Mutations in p53 or alterations in its regulatory network are major driving forces in tumorigenesis. As multiple studies indicate beneficial effects for hyperthermic treatments during radiation- or chemotherapy of human cancers, we aimed to understand how p53 dynamics after genotoxic stress are modulated by changes in temperature across a physiological relevant range. To this end, we employed a combination of time-resolved live-cell microscopy and computational analysis techniques to characterise the p53 response in thousands of individual cells. Our results demonstrate that p53 dynamics upon ionizing radiation are temperature dependent. In the range of 33 °C to 39 °C, pulsatile p53 dynamics are modulated in their frequency. Above 40 °C, which corresponds to mild hyperthermia in a clinical setting, we observed a reversible phase transition towards sustained hyperaccumulation of p53 disrupting its canonical response to DNA double strand breaks. Moreover, we provide evidence that mild hyperthermia alone is sufficient to induce a p53 response in the absence of genotoxic stress. These insights highlight how the p53-mediated DNA damage response is affected by alterations in the physical state of a cell and how this can be exploited by appropriate timing of combination therapies to increase the efficiency of cancer treatments.

Genomic analysis of lncRNA and mRNA profiles in circulating exosomes of patients with rheumatic heart disease

Rheumatic heart disease (RHD) remains one of the most common cardiovascular conditions in developing countries. Accumulating evidence suggests that circulating exosomes and their cargoes, including mRNA and long noncoding RNA (lncRNA), play essential roles in many cardiovascular diseases. However, their specific roles in RHD remain unexplored. In the present study, we identified 231 lncRNAs and 179 mRNAs differentially expressed in the circulating exosomes harvested from RHD patients compared to healthy controls. We performed gene ontology (GO) and KEGG pathway analysis, and identified five pairs of lncRNAs and their flanking coding genes simultaneously dysregulated in the circulating exosomes. Collectively, we provide the first transcriptome analysis identifying differentially expressed lncRNAs and mRNAs in circulating exosomes of RHD patients, which may bring valuable insights for the discovery of potential biomarkers and therapeutic targets for RHD.

Inhibition of miR‑155‑5p attenuates the valvular damage induced by rheumatic heart disease

Autoimmunity is involved in the valvular damage caused by rheumatic heart disease (RHD). Increased evidence has linked microRNAs (miRNAs/miRs) to autoimmune disease. Signal transducer and activator of transcription 3 (STAT3) and sphingosine-1-phosphate receptor 1 (S1PR1) and suppressor of cytokine signaling 1 (SOCS1) have been widely studied for their roles in autoimmunity and inflammation. Thus, the current study aims to investigate the role played by miR-155-5p in RHD-induced valvular damage via the S1PR1, SOCS1/STAT3 and interleukin (IL)-6/STAT3 signaling pathways. An RHD rat model was induced by inactivated Group A streptococci and complete Freund's adjuvant. A recombinant adeno-associated virus (AAV-miR155-inhibitor) was used to inhibit the expression of miR-155-5p in the heart. Inflammation and fibrosis were assessed by hematoxylin and eosin staining and Sirius red staining. The expression of miR-155-5p in valvular tissues and serum exosomes was detected by reverse transcription-quantitative PCR. S1PR1, SOCS1, STAT3, phosphorylated STAT3, IL-6 and IL-17 protein expression was detected by western blotting and immunohistochemistry. The relationships between miR-155-5p and S1PR1 and SOCS1 were detected by dual luciferase assays. Cytokine concentrations were measured by ELISA. The expression of miR-155-5p in valve tissues and serum exosomes was increased along with decreased S1PR1 and activated SOCS1/STAT3 signaling in the RHD model. The expression of IL-6 and IL-17 was increased in the valves and the serum. Dual luciferase assays showed that miR-155-5p directly targeted S1PR1 and SOCS1. Inhibition of valvular miR-155-5p through AAV pretreatment increased S1PR1 expression and inhibited activation of the SOCS1/STAT3 signal pathway as a result of attenuated valvular inflammation and fibrosis as well as a decrease in IL-6 and IL-17 in the valves and serum. These results suggest that inhibition of miR-155-5p can reduce RHD-induced valvular damage via the S1PR1, SOCS1/STAT3 and IL-6/STAT3 signaling pathways.

Lessons to be learned: Using National Immunisation strategies to improve adherence to acute rheumatic fever secondary prophylaxis

Rheumatic heart disease, as a result of a single or recurrent episode of acute rheumatic fever (ARF), remains a significant cause of morbidity and mortality in northern and remote Australia; ARF has a peak incidence among 5-14-year-old Aboriginal and Torres Strait Islander children. Long-term regular benzathine penicillin G injections are the only currently successful secondary prevention strategy; however, rates of adherence remain critically low. In contrast, rates of adherence to immunisations on the National Immunisation Program (NIP) Schedule are high, even among this target population. This article compares strategies used to implement and improve ARF secondary prophylaxis with those used in the NIP. Some successful NIP strategies, such as Service Incentive Payment for health providers, home-visiting delivery models and integration into the National Immunisation Register, if applied to ARF secondary prophylaxis have the potential to improve benzathine penicillin G adherence.

Influence of IL-1β, STAT3 & 5 and TLR-5 gene polymorphisms on rheumatic heart disease susceptibility in north Indian population

BACKGROUND

Rheumatic heart disease (RHD) is the most serious complication of heart that comprises inflammatory reactions in heart valves. Many studies have demonstrated the contribution of host genetic factors in susceptibility to RHD and many cytokine gene variants have been linked with susceptibility to RHD. We sought to determine the role of genetic variants in IL-1β, STAT3, STAT5B and TLR5 genes in conferring risk of RHD in two cohorts of RHD patients.

METHODS

The study included 400 echocardiography confirmed RHD patients and 300 controls from North Indian Population. We categorized RHD patients into two sub-groups based on involvement of heart valves, mitral valve lesion alone (MVL), and combined valve lesions including mitral valve (CVL). Genotyping for all the polymorphisms was done using TaqMan /PCR-RFLP methods.

RESULTS

Our results showed that the genotypic frequencies of IL-1β, STAT3, STAT5B andTLR5 genes polymorphisms were significantly associated with RHD risk. To validate our results, we performed a replication study in additional 200 cases with similar clinical characteristics and results again confirmed consistent findings with RHD risk. In subgroup analysis, STAT3 polymorphism remained significant with MVL in RHD patients.

CONCLUSION

IL-1β, STAT3, STAT5B and TLR5 genes polymorphism may be useful markers for the identification of individuals with high risk of RHD in the susceptible population.

Group G Streptococcus Induces an Autoimmune Carditis Mediated by Interleukin 17A and Interferon γ in the Lewis Rat Model of Rheumatic Heart Disease

Acute rheumatic fever and rheumatic heart disease (ARF/RHD) have long been described as autoimmune sequelae of Streptococcus pyogenes or group A streptococcal (GAS) infection. Both antibody and T-cell responses against immunodominant GAS virulence factors, including M protein, cross-react with host tissue proteins, triggering an inflammatory response leading to permanent heart damage. However, in some ARF/RHD-endemic regions, throat carriage of GAS is low. Because Streptococcus dysgalactiae subspecies equisimilis organisms, also known as β-hemolytic group C streptococci and group G streptococci (GGS), also express M protein, we postulated that streptococci other than GAS may have the potential to initiate or exacerbate ARF/RHD. Using a model initially developed to investigate the uniquely human disease of ARF/RHD, we have discovered that GGS causes interleukin 17A/interferon γ-induced myocarditis and valvulitis, hallmarks of ARF/RHD. Remarkably the histological, immunological, and functional changes in the hearts of rats exposed to GGS are identical to those exposed to GAS. Furthermore, antibody cross-reactivity to cardiac myosin was comparable in both GGS- and GAS-exposed animals, providing additional evidence that GGS can induce and/or exacerbate ARF/RHD.

Molecular Mimicry, Autoimmunity, and Infection: The Cross-Reactive Antigens of Group A Streptococci and their Sequelae

The group A streptococci are associated with a group of diseases affecting the heart, brain, and joints that are collectively referred to as acute rheumatic fever. The streptococcal immune-mediated sequelae, including acute rheumatic fever, are due to antibody and cellular immune responses that target antigens in the heart and brain as well as the group A streptococcal cross-reactive antigens as reviewed in this article. The pathogenesis of acute rheumatic fever, rheumatic heart disease, Sydenham chorea, and other autoimmune sequelae is related to autoantibodies that are characteristic of autoimmune diseases and result from the immune responses against group A streptococcal infection by the host. The sharing of host and streptococcal epitopes leads to molecular mimicry between the streptococcal and host antigens that are recognized by the autoantibodies during the host response. This article elaborates on the discoveries that led to a better understanding of the pathogenesis of disease and provides an overview of the history and the most current thought about the immune responses against the host and streptococcal cross-reactive antigens in group A streptococcal sequelae.

Acute rheumatic fever associated with tenosynovitis and a unique cytokine profile

Acute rheumatic fever (ARF), caused by group A β-hemolytic streptococcus infection, is characterized by inflammation affecting several organs. There are few reports on magnetic resonance imaging (MRI) findings in patients with ARF. An 8-year-old Japanese boy presented with a prolonged fever of unknown cause and swelling of his right hand. MRI of his hand revealed tenosynovitis. Migratory arthritis and erythema marginatum appeared following the hand swelling. We diagnosed him as having ARF based on the clinical course and serological testing for group A β-hemolytic streptococcus. His serum interleukin-18 levels were lower than those typically seen in cases of systemic juvenile idiopathic arthritis (sJIA). After treatment with naproxen, his symptoms improved immediately. In conclusion, MRI findings of tenosynovitis may be useful for the diagnosis of not only sJIA but also ARF in patients presenting with a fever of unknown origin. Subsequently, the diagnosis of ARF can be confirmed with specific serological tests. Serum interleukin-18 levels may be helpful in the differential diagnosis of ARF and sJIA. Although ARF is rare in developed countries, including Japan, early diagnosis and appropriate treatment are important to prevent rheumatic heart disease.

Rheumatic heart disease in the modern era: recent developments and current challenges

Rheumatic heart disease (RHD) remains a major cause of preventable death and disability in children and young adults. Despite significant advances in medical technology and increased understanding of disease mechanisms, RHD continues to be a serious public health problem throughout the world, especially in low- and middle-income countries. Echocardiographic screening has played a key role in improving the accuracy of diagnosing RHD and has highlighted the disease burden. Most affected patients present with severe valve disease and limited access to life-saving cardiac surgery or percutaneous valve intervention, contributing to increased mortality and other complications. Although understanding of disease pathogenesis has advanced in recent years, key questions remain to be addressed. Preventing or providing early treatment for streptococcal infections is the most important step in reducing the burden of this disease.

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.

Antibodies in the Diagnosis, Prognosis, and Prediction of Psychotic Disorders

Blood-based biomarker discovery for psychotic disorders has yet to impact upon routine clinical practice. In physical disorders antibodies have established roles as diagnostic, prognostic and predictive (theranostic) biomarkers, particularly in disorders thought to have a substantial autoimmune or infective aetiology. Two approaches to antibody biomarker identification are distinguished: a "top-down" approach, in which antibodies to specific antigens are sought based on the known function of the antigen and its putative role in the disorder, and emerging "bottom-up" or "omics" approaches that are agnostic as to the significance of any one antigen, using high-throughput arrays to identify distinctive components of the antibody repertoire. Here we review the evidence for antibodies (to self-antigens as well as infectious organism and dietary antigens) as biomarkers of diagnosis, prognosis, and treatment response in psychotic disorders. Neuronal autoantibodies have current, and increasing, clinical utility in the diagnosis of organic or atypical psychosis syndromes. Antibodies to selected infectious agents show some promise in predicting cognitive impairment and possibly other symptom domains (eg, suicidality) within psychotic disorders. Finally, infectious antibodies and neuronal and other autoantibodies have recently emerged as potential biomarkers of response to anti-infective therapies, immunotherapies, or other novel therapeutic strategies in psychotic disorders, and have a clear role in stratifying patients for future clinical trials. As in nonpsychiatric disorders, combining biomarkers and large-scale use of "bottom-up" approaches to biomarker identification are likely to maximize the eventual clinical utility of antibody biomarkers in psychotic disorders.

Association of IL17 and IL23R gene polymorphisms with rheumatic heart disease in South Indian population

BACKGROUND

IL-23/Th17 signaling pathway plays a crucial role in the cell-mediated immune response against bacterial infections and also in the pathogenesis of inflammatory and autoimmune diseases. Recent studies indicate that Th17 cell-associated cytokines are involved in the progression and maintenance of valvular lesions in rheumatic heart disease (RHD). Variants in the genes of cytokines that are potentially involved in Th17 response may influence interindividual differences in their expression levels, thereby contributing to the pathogenesis of immune-mediated diseases such as RHD.

OBJECTIVE

The aim of the study is to investigate the association of IL17A, IL17F, and IL23R gene variants with the risk perception of RHD.

METHODS

A total of 225 individuals (99 RHD patients and 126 healthy siblings) were recruited for the study. The IL17A (rs2275913), IL17F (rs763780), and IL23R (rs10889677) polymorphisms were determined by polymerase chain reaction restriction fragment length polymorphisms and amplification-refractory mutation system-polymerase chain reaction methods, respectively.

RESULTS

The frequency of IL17A (rs2275913) A/A genotype was significantly high in pooled RHD patients (odds ratio [OR] = 2.76; p_c = 0.021), rheumatic fever (RF) patients (OR = 14.5; p_c = 0.0001), and mitral valvular lesions patients (OR = 2.74; p_c = 0.039) when compared to healthy siblings. However, the IL17F (rs763780) and IL23R (rs10889677) polymorphisms did not show any association with RHD.

CONCLUSIONS

The results suggest that IL17A (rs2275913) polymorphism is associated with the development of RF/RHD in South Indian population. Further studies are required to substantiate the association of these genes with the disease risk.

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.

Cardiac applications of hyperpolarised magnetic resonance

Cardiovascular disease is the leading cause of death world-wide. It is increasingly recognised that cardiac pathologies show, or may even be caused by, changes in metabolism, leading to impaired cardiac energetics. The heart turns over 15 times its own weight in ATP every day and thus relies heavily on the availability of substrates and on efficient oxidation to generate this ATP. A number of old and emerging drugs that target different aspects of metabolism are showing promising results with regard to improved cardiac outcomes in patients. A non-invasive imaging technique that could assess the role of different aspects of metabolism in heart disease, as well as measure changes in cardiac energetics due to treatment, would be valuable in the routine clinical care of cardiac patients. Hyperpolarised magnetic resonance spectroscopy and imaging have revolutionised metabolic imaging, allowing real-time metabolic flux assessment in vivo for the first time. In this review we summarise metabolism in the healthy and diseased heart, give an introduction to the hyperpolarisation technique, 'dynamic nuclear polarisation' (DNP), and review the preclinical studies that have thus far explored healthy cardiac metabolism and different models of human heart disease. We furthermore show what advances have been made to translate this technique into the clinic, what technical challenges still remain and what unmet clinical needs and unexplored metabolic substrates still need to be assessed by researchers in this exciting and fast-moving field.

MBL2 gene polymorphism rs1800450 and rheumatic fever with and without rheumatic heart disease: an Egyptian pilot study

BACKGROUND

Rheumatic fever (RF) is the result of an autoimmune response to pharyngitis caused by infection with Streptococcus pyogenes. RF is most prevalent in Africa and the Middle East. Rheumatic heart disease (RHD) is the most serious complication of RF. Mannose-binding lectin 2 gene (MBL2) has been reported to be correlated with different cardiac conditions. In Egyptian patients as a new studied ethnic population, it is the first time to evaluate the association between MBL2 gene polymorphism rs1800450 and RF with and without RHD.

METHODS

One hundred and sixty RF patients (80 with RHD and 80 without RHD) and eighty healthy ethnically matched controls were studied. MBL2 (rs1800450) was genotyped by real-time PCR using TaqMan® allele discrimination assay. The MBL level was measured by ELISA. Westergren erythrocytes sedimentation rate (ESR), anti-streptolysin O titer (ASOT), C-reactive protein (CRP) and complements (C3 and C4) were determined.

RESULTS

The AA genotype with high production of MBL was associated with increased risk of RHD more than the B allele carrying subjects. However, MBL2 genotype related to the low production of MBL was more frequently observed in those patients without RHD.

CONCLUSIONS

Our results suggested the involvement of MBL2 (rs1800450) polymorphism and its protein in RHD pathogenesis. Also, it might be a promising future strategy to utilize this polymorphism to help differentiate patients with RHD from those without RHD.

Vimentin and Anti Vimentin Antibodies in Chagas' Disease

BACKGROUND

Vimentin is a main structural protein of the cell, a component of intermediate cell filaments and immersed in cytoplasm. Vimentin is mimicked by some bacterial proteins and anti-vimentin antibodies occur in autoimmune cardiac disease, as rheumatic fever. In this work we studied vimentin distribution on LLC-MK2 cells infected with T. cruzi and anti-vimentin antibodies in sera from several clinical pictures of Chagas' disease or American Trypanosomiasis, in order to elucidate any vimentin involvement in the humoral response of this pathology.

OBJECTIVE

We standardized an indirect immunofluorescence assay (IFI) to determine sub cellular expression in either parasites and host cells, and ELISA to evaluate anti-vimentin antibodies in sera fron chagasic patients.

METHODS

We analyzed the distribution of vimentin in culture cells using indirect fluorescent assays, using as external controls anti-T. cruzi sera, derived from chronic infected patients for identification of the parasites in the same model. After infection and growth of T.cruzi amastigotes, those cells express larger amounts of vimentin, with heavy staining of cytoplasm outside the parasitophorous vacuole and some particle shadowing patterns, suggesting that vimentin are associated with cell cytoplasm. Anti-vimentin antibodies were present in most American trypanosomiasis samples, but notably, they are much more present in acute (76, 9%) or clinical defined syndromes, especially cardiac disease (87, 9%). Paradoxically, they were relatively infrequent in asymptomatic (25%) infected patients, which had a clearly positive serological reaction to parasite antigens, but had low frequency of anti-vimentin antibodies, similar to controls (2,5%).

CONCLUSION

Our current data revealed that anti-vimentin antibodies induced during T. cruzi infection could be a marker of active disease in the host and its levels could also justify drug therapy in American Trypanosomiasis chronic infection, as a large group of asymptomatic patients would be submitted to treatment with frequent adverse reactions of the available drugs. Anti-vimentin antibodies could be a marker of cardiac muscle cell damage, appearing in American Trypanosomiasis patients during active muscle cell damage.

Streptococcal pharyngitis and rheumatic heart disease: the superantigen hypothesis revisited

Streptococcus pyogenes is a human-specific and globally prominent bacterial pathogen that despite causing numerous human infections, this bacterium is normally found in an asymptomatic carrier state. This review provides an overview of both bacterial and human factors that likely play an important role in nasopharyngeal colonization and pharyngitis, as well as the development of acute rheumatic fever and rheumatic heart disease. Here we highlight a recently described role for bacterial superantigens in promoting acute nasopharyngeal infection, and discuss how these immune system activating toxins could be crucial to initiate the autoimmune process in rheumatic heart disease.