Molecular mimicry between Streptococcus pyogenes Ags and human proteins has been considered as a mechanism leading to autoimmune reactions in rheumatic fever and rheumatic heart disease (RHD). Cardiac myosin has been shown as a putative autoantigen recognized by autoantibodies of rheumatic fever patients. We assessed the human heart-intralesional T cell response against human light meromyosin (LMM) and streptococcal M5 peptides and mitral-valve-derived proteins by proliferation assay. Cytokines induced by LMM peptides were also evaluated. The frequency of intralesional T cell clones that recognized LMM peptides was 63.2%. Thirty-four percent of T cell clones presented cross-reactivity with different patterns: 1) myosin and valve-derived proteins; 2) myosin and streptococcal M5 peptides; and 3) myosin, valve-derived proteins and M5 peptides. In addition, several LMM peptides were recognized simultaneously showing a multiple reactivity pattern of heart-infiltrating T cells. Inflammatory cytokines (IFN-γ and TNF-α) were predominantly produced by heart-infiltrating T cells upon stimulation with LMM peptides. The alignment of LMM and streptococcal M5 peptides showed frequent homology among conserved amino acid substitutions. This is the first study showing the cellular response by human heart-infiltrating T cells against cardiac myosin epitopes in RHD patients. The high percentage of reactivity against cardiac myosin strengthens its role as one of the major autoantigens involved in rheumatic heart lesions. T cell reactivity toward myosin epitopes in RHD patients may also trigger the broad recognition of valvular proteins with structural or functional similarities.

Rheumatic heart disease (RHD) is a sequel of post-streptococcal throat infection. Molecular mimicry between streptococcal and heart components has been proposed as the triggering factor of the disease, and CD4(+) T cells have been found predominantly at pathological sites in the heart of RHD patients. These infiltrating T cells are able to recognize streptococcal M protein peptides, involving mainly 1-25, 81-103 and 163-177 N-terminal amino acids residues. In the present work we focused on the TCR beta chain family (TCR BV) usage and the degree of clonality assessed by beta chain complementarity-determining region (CDR)-3 length analysis. We have shown that in chronic RHD patients, TCR BV usage in peripheral blood mononuclear cells (PBMC) paired with heart-infiltrating T cell lines (HIL) is not suggestive of a superantigen effect. Oligoclonal T cell expansions were more frequently observed in HIL than in PBMC. Some major BV expansions were shared between the mitral valve (Miv) and left atrium (LA) T cell lines, but an in-depth analysis of BJ segments usage in these shared expansions as well as nucleotide sequencing of the CDR3 regions suggested that different antigenic peptides could be predominantly recognized in the Miv and the myocardium. Since different antigenic proteins probably are constitutively represented in myocardium and valvular tissue, these findings could suggest a differential epitope recognition at the two lesional heart sites after a common initial bacterial challenge.

Objectives: to determine causes and variables related to newborn deaths of a neonate intensive care unite (ICU) in the Southern

OBJECTIVE: In order to determine the relationship between some maternal anthropometric indicators and birth weight, crown-heel length and newborn's head circumference, 92 pregnant women were followed through at the prenatal service of hospital in S. Paulo, Brazil. MATERIAL AND METHOD: The following variables were established for the mother: weight, height, mid-upper arm circumference, pre-pregnancy weight, gestational weight gain and Quetelet's index. For the newborn the following variables were recorded: birth weight, crown-heel length, head circumference and gestational age by Dubowitz's method. RESULTS: Significant associations were noted between gestational age and newborn variables. In addition, maternal mid-arm circumference (MUAC) and pre-pregnancy weight were found to be positively correlated to birth weight (r=0.399; r=0.378, respectively). The multivariate linear regression shows that gestational age, mother's arm circumference and pre-pregnancy weight continue to be significant predictors of birth weight. On the other hand, only gestational age and mother's age was associated with crown-heel length. Similarly MUAC was significantly associated with crown-heel length (r= 0.306; P=0.0030). CONCLUSION: Maternal mid-upper arm circumference is a potential indicator of maternal nutritional status. It could be used in association with other anthropometric measurements, instead of pre-pregnancy weight, as an alternative indicator to assess women at risk of poor pregnancy outcome.

Heart lesions of rheumatic heart disease (RHD) patients contain T-cell clones that recognize heart proteins and streptococcal M peptides. To functionally characterize heart-infiltrating T lymphocytes, we evaluated their cytokine profile, both directly in situ and in T-cell lines derived from the heart (HIL). Interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, interleukin (IL)-4, and IL-10 expressions were characterized in 20 heart tissue infiltrates from 14 RHD patients by immunohistochemistry. IFN-gamma-, TNF-alpha-, and IL-10-positive cells were consistently predominant, whereas IL-4 was scarce in the valves. In agreement with these data, the in vitro experiments, in which 13 HILs derived from heart samples of eight patients were stimulated with M5 protein and the immunodominant M5 (81-96) peptide, IL-4 was detected in HIL derived from the atrium (three of six) but not from the valve (zero of seven). IFN-gamma and IL-10 production were detected in culture supernatants in 11 of 13 and 6 of 12 HILs, respectively. The predominant IFN-gamma and TNF-alpha expression in the heart suggests that Th1-type cytokines could mediate RHD. Unlike in reversible myocardium inflammation, the significantly lower IL-4 expression in the valvular tissue (P = 0.02) may contribute to the progression of the RHD leading to permanent valvular damage (relative risk, 4.3; odds ratio, 15.8). The lack of IL-4 in vitro production by valve-derived HIL also emphasizes the more severe tissue destruction in valves observed in RHD.

No abstract

Rheumatic fever (RF) is an autoimmune disease which affects more than 20 million children in developing countries. It is triggered by Streptococcus pyogenes throat infection in untreated susceptible individuals. Carditis, the most serious manifestation of the disease, leads to severe and permanent valvular lesions, causing chronic rheumatic heart disease (RHD). We have been studying the mechanisms leading to pathological autoimmunity in RF/RHD for the last 15 years. Our studies allowed us a better understanding of the cellular and molecular pathogenesis of RHD, paving the way for the development of a safe vaccine for a post-infection autoimmune disease. We have focused on the search for protective T and B cell epitopes by testing 620 human blood samples against overlapping peptides spanning 99 residues of the C-terminal portion of the M protein, differing by one amino acid residue. We identified T and B cell epitopes with 22 and 25 amino acid residues, respectively. Although these epitopes were from different regions of the C-terminal portion of the M protein, they showed an identical core of 16 amino acid residues. Antibodies against the B cell epitope inhibited bacterial invasion/adhesion in vitro. Our results strongly indicated that the selected T and B cell epitopes could potentially be protective against S. pyogenes.

The authors carried out a literature review of the subject "stillbirth", with special emphasis on its conceptual and epidemiological features, aimed at highlighting its importance as a perinatal health indicator.