Inhibition of Macrophage Recruitment to Heart Valves Mediated by the C-C Chemokine Receptor Type 2 Attenuates Valvular Inflammation Induced by Group A Streptococcus in Lewis Rats.

BACKGROUND: Rheumatic heart disease (RHD) is an autoimmune disease caused by recurrent infections of Group A streptococcus (GAS), ultimately leading to inflammation and the fibrosis of heart valves. Recent studies have highlighted the crucial role of C-C chemokine receptor type 2-positive (CCR2+) macrophages in autoimmune diseases and tissue fibrosis. However, the specific involvement of CCR2+ macrophages in RHD remains unclear. METHODS: This study established an RHD rat model using inactivated GAS and complete Freund's adjuvant, demonstrating a correlation between CCR2+ macrophages and fibrosis in the mitral valves of these rats. RESULTS: Intraperitoneal injection of the CCR2 antagonist Rs-504393 significantly reduced macrophage infiltration, inflammation, and fibrosis in valve tissues of RHD rats compared to the solvent-treated group . Existing evidence suggests that C-C motif chemokine ligand 2 (CCL2) acts as the primary recruiting factor for CCR2+ cells. To validate this, human monocytic leukemia cells (THP-1) were cultured in vitro to assess the impact of recombinant CCL2 protein on macrophages. CCL2 exhibited pro-inflammatory effects similar to lipopolysaccharide (LPS), promoting M1 polarization in macrophages. Moreover, the combined effect of LPS and CCL2 was more potent than either alone. Knocking down CCR2 expression in THP-1 cells using small interfering RNA suppressed the pro-inflammatory response and M1 polarization induced by CCL2. CONCLUSIONS: The findings from this study indicate that CCR2+ macrophages are pivotal in the valvular remodeling process of RHD. Targeting the CCL2/CCR2 signaling pathway may therefore represent a promising therapeutic strategy to alleviate valve fibrosis in RHD.

Genome-Wide Analysis of Genetic Risk Factors for Rheumatic Heart Disease in Aboriginal Australians Provides Support for Pathogenic Molecular Mimicry.

Background: Rheumatic heart disease (RHD) after group A streptococcus (GAS) infections is heritable and prevalent in Indigenous populations. Molecular mimicry between human and GAS proteins triggers proinflammatory cardiac valve-reactive T cells. Methods: Genome-wide genetic analysis was undertaken in 1263 Aboriginal Australians (398 RHD cases; 865 controls). Single-nucleotide polymorphisms were genotyped using Illumina HumanCoreExome BeadChips. Direct typing and imputation was used to fine-map the human leukocyte antigen (HLA) region. Epitope binding affinities were mapped for human cross-reactive GAS proteins, including M5 and M6. Results: The strongest genetic association was intronic to HLA-DQA1 (rs9272622; P = 1.86 × 10-7). Conditional analyses showed rs9272622 and/or DQA1*AA16 account for the HLA signal. HLA-DQA1*0101_DQB1*0503 (odds ratio [OR], 1.44; 95% confidence interval [CI], 1.09-1.90; P = 9.56 × 10-3) and HLA-DQA1*0103_DQB1*0601 (OR, 1.27; 95% CI, 1.07-1.52; P = 7.15 × 10-3) were risk haplotypes; HLA_DQA1*0301-DQB1*0402 (OR 0.30, 95%CI 0.14-0.65, P = 2.36 × 10-3) was protective. Human myosin cross-reactive N-terminal and B repeat epitopes of GAS M5/M6 bind with higher affinity to DQA1/DQB1 alpha/beta dimers for the 2-risk haplotypes than the protective haplotype. Conclusions: Variation at HLA_DQA1-DQB1 is the major genetic risk factor for RHD in Aboriginal Australians studied here. Cross-reactive epitopes bind with higher affinity to alpha/beta dimers formed by risk haplotypes, supporting molecular mimicry as the key mechanism of RHD pathogenesis.

Predicted Coverage and Immuno-Safety of a Recombinant C-Repeat Region Based Streptococcus pyogenes Vaccine Candidate.

The C-terminal region of the M-protein of Streptococcus pyogenes is a major target for vaccine development. The major feature is the C-repeat region, consisting of 35-42 amino acid repeat units that display high but not perfect identity. SV1 is a S. pyogenes vaccine candidate that incorporates five 14mer amino acid sequences (called J14i variants) from differing C-repeat units in a single recombinant construct. Here we show that the J14i variants chosen for inclusion in SV1 are the most common variants in a dataset of 176 unique M-proteins. Murine antibodies raised against SV1 were shown to bind to each of the J14i variants present in SV1, as well as variants not present in the vaccine. Antibodies raised to the individual J14i variants were also shown to bind to multiple but different combinations of J14i variants, supporting the underlying rationale for the design of SV1. A Lewis Rat Model of valvulitis was then used to assess the capacity of SV1 to induce deleterious immune response associated with rheumatic heart disease. In this model, both SV1 and the M5 positive control protein were immunogenic. Neither of these antibodies were cross-reactive with cardiac myosin or collagen. Splenic T cells from SV1/CFA and SV1/alum immunized rats did not proliferate in response to cardiac myosin or collagen. Subsequent histological examination of heart tissue showed that 4 of 5 mice from the M5/CFA group had valvulitis and inflammatory cell infiltration into valvular tissue, whereas mice immunised with SV1/CFA, SV1/alum showed no sign of valvulitis. These results suggest that SV1 is a safe vaccine candidate that will elicit antibodies that recognise the vast majority of circulating GAS M-types.

Group C Streptococcus Causing Rheumatic Heart Disease in a Child.

BACKGROUND: Human infection with group C Streptococcus is extremely rare and a select number of cases have been reported to cause acute pharyngitis, acute glomerulonephritis, skin and soft tissue infections, septic arthritis, osteomyelitis, pneumonitis, and bacteremia. In pediatrics, this bacteria is known to cause epidemic food-borne pharyngitis, pneumonia, endocarditis, and meningitis, and has reportedly been isolated in the blood, meninges, sinuses, fingernail, peritonsillar abscess, and thyroglossal duct cyst, among others. CASE REPORT: Our patient was a 7-year-old previously healthy female who presented with abnormal movements of her upper body and grimaces of her face that progressively worsened over time. Initial laboratory resulted revealed 3+ protein on urinalysis and elevated antistreptolysin-O and anti-DNAse antibody levels, and echocardiogram showed mild-to-moderate mitral regurgitation. We describe a rare case of group C Streptococcus resulting in rheumatic heart disease in a child, with a detailed review of the literature pertaining to the diagnosis and management of this infection. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Early recognition of rheumatic heart disease is crucial in the overall outcome of the condition and therefore knowledge of the symptoms associated with condition is also imperative. Group C Streptococcus is rarely associated with rheumatic heart disease and most children exhibiting acute onset of common symptoms, such as chorea, fever, carditis, and rash (erythema marginatum) will present to the emergency department first. Increased awareness and prompt recognition, as done with this child, will result in proper follow-up and adequate management of this condition in all patients.

Demonstration of Chlamydophila pneumoniae, Mycoplasma pneumoniae, Cytomegalovirus, and Epstein-Barr virus in atherosclerotic coronary arteries, nonrheumatic calcific aortic and rheumatic stenotic mitral valves by polymerase chain reaction.

OBJECTIVE: The aim of this study was to investigate whether bacterial and viral infectious agents can be demonstrated in atherosclerotic lesions of patients with coronary artery disease (CAD) as well as in stenotic aortic and mitral valves from patients undergoing heart valve replacement. METHODS: In this cross-sectional study, the presence of Chlamydophila pneumoniae, Mycoplasma pneumoniae, Cytomegalovirus (CMV), and Epstein-Barr virus (EBV) was investigated by polymerase chain reaction in atherosclerotic and non-atherosclerotic vascular samples taken from patients undergoing coronary artery bypass surgery due to CAD, and from patients undergoing aortic (AVR) and/or mitral valve replacement (MVR) secondary to valvular stenosis. For statistical analyses ANOVA, Chi-square test or Fisher's exact test were used. RESULTS: The presence of C. pneumoniae, M. pneumoniae, and CMV in atherosclerotic versus non-atherosclerotic samples was as follows: 30% vs. 16.7% (p=0.222), 6.7% vs. 3.3% (p=0.554), and 10% vs. 0% (p=0.076), respectively. In valve group, same pathogens were present in AVR and MVR patients as follows: 24.2% vs. 21.4% (p=0.773), 9.1% vs. 7.1% (p=0.758), and 21.2% vs. 11.9% (p=0.275). EBV DNA was not detected in any of vascular specimens, but in one (3%) patient with AVR (p=0.256). CONCLUSION: Our results suggest that C. pneumoniae, M. pneumoniae, and CMV are present with similar frequency both in atherosclerotic and non-atherosclerotic vessels. We conclude that although non-atherosclerotic, vascular samples of CAD patients are invaded by infectious agents as like as atherosclerotic vessels. We further conclude that C. pneumoniae, M. pneumoniae, and CMV are present in stenotic aortic and mitral valves and atherosclerotic tissues with similar frequency indicating that atherosclerosis and valvular stenosis might share a common etiology related to infection.

Detection of nanobacteria-like material from calcified cardiac valves with rheumatic heart disease.

BACKGROUND: Nanobacterium contributes to pathological calcification in human renal stones and psammoma bodies in ovarian cancer. Pathological calcification is also present in cardiac valves with rheumatic heart disease. The aim of this study was to detect, isolate, culture, and characterize nanobacteria-like material from human calcified cardiac valves with rheumatic heart disease. METHODS: Normal and calcified cardiac valve groups, as well as positive (nanobacteria strain Se90) and negative (serum radiated with 30 kGy of γ-ray) control groups, were included in this study. Part of each valve was immunostained with nanobacterial antibody 8D10, and the remaining parts were homogenized, filtered, and maintained in culture. The cultures were checked with a microscope weekly. Culture medium at different time points was analyzed with a spectrophotometer. The cultures maintained for 3 weeks were further examined with immunofluorescence double staining and transmission electron microscopy. RESULTS: While 26 of 29 calcified valves stained positive for 8D10 antibody, all normal valves stained negative. Mobile tiny particles were observed under a microscope in the calcified valve group and the Se90 group. Optical densities were significantly different among groups (P<.001). Immunofluorescence double staining displayed tiny green fluorescence particles in the calcified valve group, in the Se90 group, and in two samples of the normal valve group. Transmission electron microscopy analysis indicated that cultured particles from calcified valves ranging in size from 88 to 341 nm had an obvious cell membrane structure similar to that of Se90. CONCLUSIONS: The nanobacteria-like material has been isolated and cultured from calcified cardiac valves with rheumatic heart disease, and its characteristics are similar to those of Se90.

[Epidemiological survey of rheumatic heart disease in schoolchildren in Guangdong and Xinjiang].

OBJECTIVE: To investigate the prevalence of rheumatic heart disease (RHD) among schoolchildren in Guangdong Province and Xinjiang Uygur Autonomous Region. METHODS: Using a cluster sampling method, an epidemiological survey of RHD was conducted in 16 682 primary and high school students by auscultation in Guangdong Province and Xinjiang Uygur Autonomous Region from 2005 to 2006. Review of the clinical records, RHD survey in adults, and examination of the positivity rate of group A beta-hemolytic Streptococcus (GAS) by throat swab cultures in the students aged between 9 and 12 years in the sampled schools were also carried out. RESULTS: No RHD patient was found in the sampled population. In Xinjiang, the prevalence of RHD was 12.9/1000 among adults, higher than that (2.2/1000) in Guangdong Province. The GAS-positive rate in the schoolchildren in Xinjiang ranged from 9.8% to 12.6%, higher than that in Guangdong (2.3%-3.9%). CONCLUSION: The GAS-positive rate among children and incidence of RHD in adults are higher in Xinjiang than in Guangdong. The prevalence of RHD among the schoolchildren shows a reduction compared with that in 1994.

Triple-valve treatment for prosthetic valve endocarditis occurring 20 years after implantation of a Carpentier-Edwards pericardial bioprosthesis in the aortic valve.

A 68-year-old woman had undergone aortic valve replacement and open commissurotomy 20 years previously. At the beginning of 2008, fever, cold, and heart failure symptoms were noted. On blood culture, Streptococcus oralis was detected three times. Surgery was performed under a diagnoses of prosthetic valve endocarditis in the aortic valve, mitral stenosis and insufficiency, and tricuspid insufficiency. Techniques consisted of additional aortic valve replacement, mitral valve replacement, and tricuspid annuloplasty. Vegetation was macroscopically and pathologically observed in the extirpated Carpentier-Edwards pericardial bioprosthesis that had been placed in the aortic valve. There was no postoperative recurrent inflammatory response. The patient was discharged 32 days after surgery.

Presencia de ADN bacteriano en el tejido valvular de pacientes con cardiopatía reumática crónica / Presence of bacterial DNA in valvular tissue of patients with rheumatic heart disease

Background: Rheumatic heart disease (RHD) is a delayed consequence of a pharyngeal infection with Group A streptococcus (GAS), usually ascribed to a cross-reactive immune response to the host cardiac tissues. Acute rheumatic fever (ARF) and its ensuing valvular sequelae are thus considered the prototype of a post-infectious autoimmune disease, with no direct evidence of residual streptococcal antigen in diseased valvular tissues. However, recent studies concerning the antigenic specificity and clonality of intralesional lymphocytes have revealed oligoclonal expansions characteristic of an antigen specific response, that might be related to GAS. Aim: To search for bacterial DNA in valvular tissue from RHD patients and controls. Material and methods: We extracted DNA from surgically excised valve specimens from 15 RHD patients and 6 non RHD controls and tested for the presence of bacterial DNA by Polymerase Chain Reaction (PCR) with primers for 16S rRNA. Results: Eighty percent (12/15) of valve specimens from RHD patients were positive for bacterial DNA, as opposed to none of the valves (n =6) from non RHD controls. Conclusions: These results suggest that GAS might persist in valvular tissue in patients with ARF and contribute to the inflammatory scarring lesion that leads to cardiovascular sequelae.

Epidemiology of infective endocarditis in Tunisia: a 10-year multicenter retrospective study.

BACKGROUND: Since the first description of infective endocarditis, the profile of the disease has evolved continuously with stable incidence. However, epidemiological features are different in developing countries compared with western countries. OBJECTIVE: To describe epidemiological, microbiological and outcome characteristics of infective endocarditis in Tunisia. PATIENTS AND METHODS: This was a descriptive multicenter retrospective study of inpatients treated for infective endocarditis from 1991 to 2000. Charts of patients with possible or definite infective endocarditis according to the Duke criteria were included in the study. RESULTS: Four hundred and forty episodes of infective endocarditis among 435 patients (242 males, 193 females; mean (SD) age=32.4 (16.8) years, range 1-78 years) were reviewed. The most common predisposing heart disease was rheumatic valvular disease (45.2%). Infective endocarditis occurred on prosthetic valves in 17.3% of cases. Causative microorganisms were identified in 50.2% of cases: streptococci (17.3%), enterococci (3.9%), staphylococci (17.9%), and other pathogens (11.1%). Blood cultures were negative in 53.6% and no microorganism was identified in 49.8%. Early valve surgery was performed in 51.2% of patients. The in-hospital mortality was 20.6%. CONCLUSION: Infective endocarditis is still frequently associated with rheumatic disease among young adults in Tunisia, with a high frequency of negative blood cultures and high in-hospital mortality, given that the population affected is relatively young.

Fungal endocarditis: an autopsy study.

Between 1990 and 2002, 237 hearts were examined at autopsy, including 16 with infective endocarditis; 6 showed fungal endocarditis. The preceding pathology was chronic rheumatic heart disease in 2 patients, one of whom had undergone double valve replacement, 2 patients had been treated for acute lymphoblastic leukemia, and one had protein-energy malnutrition. The underlying cause was unknown in one case. The organisms isolated were Aspergillus in 3 patients, Zygomycota in 1, Candida in 1, and both Candida tropicalis and Aspergillus in 1 patient. Immunosuppressed states are a cause of fungal endocarditis in India, although chronic rheumatic heart disease is the preceding pathology in the majority of patients.

Epidemiological studies on rheumatic heart disease and streptococcal carriers among school-children in Addis-Ababa, Ethiopia. Preliminary communication.

The results of the first part of epidemiological follow-up studies on rheumatic heart disease and streptococcal carriers in Addis-Ababa are presented. In 1012 school-children relatively low morbidity of rheumatic heart disease (0.49%) and relatively small percentage of carriers of A-beta-hemolytic streptococci (4.24%) were found. There was no statistically significant difference in the morbidity of rheumatic heart disease as well as in the percentage of streptococcal carriers between the two basic social groups--children of well-to-do and of poor parents. No correlations with overcrowding were found. Serological types 5/12/27 and 3/13/B3164 of group A-beta-hemolytic streptococci were isolated most frequently.

Herpesvirus hominis: isolation from human trigeminal ganglion.

Herpesvirus hominis was isolated from the trigeminal ganglion obtained at autopsy from 1 of 22 patients with no clinical evidence of active herpetic disease, and from one patient with malignant lymphoma who died with herpes zoster on the abdomen, pulmonary cytomegalic inclusion disease, and possible oral herpes simplex. Virus was isolated by cocultivation of explants of ganglion with monolayers of Vero green monkey kidney cells and required 3 weeks of culture before viral cytopathic effects were evident. These observations support the concept that latent infection of sensory ganglia may be the source of virus in recurrent herpetic disease in man.