Rheumatic fever: the interplay between host, genetics, and microbe. Lewis A. Conner memorial lecture

Pediatric neuropsychiatric disorders with motor and nonmotor phenomena

The concept of pediatric autoimmune neuropsychiatric disorders associated with group A beta-hemolytic streptococcus (PANDAS) has become seminal since first introduced more than two decades ago. At the time of this writing, most neurologists, pediatricians, psychiatrists, and general pediatricians will probably have heard of this association or treated an affected child with PANDAS. The concept of an acute-onset, and typically self-limited, postinfectious autoimmune neuropsychiatric disorder resembling PANDAS manifesting vocal and motor tics and obsessive-compulsive disorder has broadened to other putative microbes and related endogenous and exogenous disease triggers. These disorders with common features of hypometabolism in the medial temporal lobe and hippocampus in brain 18fluorodeoxyglucose positron emission tomography fused to magnetic resonance imaging (FDG PET-MRI), form a spectrum: with the neuropsychiatric disorder Tourette syndrome and PANDAS with its well-defined etiopathogenesis at one end, and pediatric abrupt-onset neuropsychiatric syndrome (PANS), alone or associated with specific bacterial and viral pathogens, at the other end. The designation of PANS in the absence of a specific trigger, as an exclusionary diagnosis, reflects the current problem in nosology.

Developing an Effective Glycan-based Vaccine for Streptococcus Pyogenes

Streptococcus pyogenes is a primary infective agent that causes approximately 700 million human infections each year, resulting in more than 500,000 deaths. Carbohydrate-based vaccines are proven to be one of the most promising subunit vaccine candidates, as the bacterial glycan pattern(s) are different from mammalian cells and show increased pathogen serotype conservancy than the protein components. In this review we highlight reverse vaccinology for use in the development of subunit vaccines against S. pyogenes, and report reproducible methods of carbohydrate antigen production, in addition to the structure-immunogenicity correlation between group A carbohydrate epitopes and alternative vaccine antigen carrier systems. We also report recent advances used to overcome hurdles in carbohydrate-based vaccine development.

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.

Towards developing a vaccine for rheumatic heart disease

Rheumatic heart disease (RHD) is the most serious manifestations of rheumatic fever, which is caused by group A Streptococcus (GAS or Streptococcus pyogenes) infection. RHD is an auto immune sequelae of GAS pharyngitis, rather than the direct bacterial infection of the heart, which leads to chronic heart valve damage. Although antibiotics like penicillin are effective against GAS infection, improper medical care such as poor patient compliance, overcrowding, poverty, and repeated exposure to GAS, leads to acute rheumatic fever and RHD. Thus, efforts have been put forth towards developing a vaccine. However, a potential global vaccine is yet to be identified due to the widespread diversity of S. pyogenes strains and cross reactivity of streptococcal proteins with host tissues. In this review, we discuss the available vaccine targets of S. pyogenes and the significance of in silico approaches in designing a vaccine for RHD.

Autoimmunity against dopamine receptors in neuropsychiatric and movement disorders: a review of Sydenham chorea and beyond

Antineuronal autoantibodies are associated with the involuntary movement disorder Sydenham chorea (SC) and paediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) which are characterized by the acute onset of tics and/or obsessive compulsive disorder (OCD). In SC and PANDAS, autoantibodies signal human neuronal cells and activate calcium calmodulin-dependent protein kinase II (CaMKII). Animal models immunized with group A streptococcal antigens demonstrate autoantibodies against dopamine receptors and concomitantly altered behaviours. Human monoclonal antibodies (mAbs) derived from SC target and signal the dopamine D2L (long) receptor (D2R). Antibodies against D2R were elevated over normal levels in SC and acute-onset PANDAS with small choreiform movements, but were not elevated over normal levels in PANDAS-like chronic tics and OCD. The expression of human SC-derived anti-D2R autoantibody V gene in B cells and serum of transgenic mice demonstrated that the human autoantibody targets dopaminergic neurones in the basal ganglia and other types of neurones in the cortex. Here, we review current evidence supporting the hypothesis that antineuronal antibodies, specifically against dopamine receptors, follow streptococcal exposures and may target dopamine receptors and alter central dopamine pathways leading to movement and neuropsychiatric disorders.

Rheumatic fever, autoimmunity, and molecular mimicry: the streptococcal connection

The group A streptococcus, Streptococcus pyogenes, and its link to autoimmune sequelae, has acquired a new level of understanding. Studies support the hypothesis that molecular mimicry between the group A streptococcus and heart or brain are important in directing immune responses in rheumatic fever. Rheumatic carditis, Sydenham chorea and a new group of behavioral disorders called pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections are reviewed with consideration of autoantibody and T cell responses and the role of molecular mimicry between the heart, brain and group A streptococcus as well as how immune responses contribute to pathogenic mechanisms in disease. In rheumatic carditis, studies have investigated human monoclonal autoantibodies and T cell clones for their crossreactivity and their mechanisms leading to valve damage in rheumatic heart disease. Although studies of human and animal sera from group A streptococcal diseases or immunization models have been crucial in providing clues to molecular mimicry and its role in the pathogenesis of rheumatic fever, study of human monoclonal autoantibodies have provided important insights into how antibodies against the valve may activate the valve endothelium and lead to T cell infiltration. Passive transfer of anti-streptococcal T cell lines in a rat model of rheumatic carditis illustrates effects of CD4+ T cells on the valve. Although Sydenham chorea has been known as the neurological manifestation of rheumatic fever for decades, the combination of autoimmunity and behavior is a relatively new concept linking brain, behavior and neuropsychiatric disorders with streptococcal infections. In Sydenham chorea, human mAbs and their expression in transgenic mice have linked autoimmunity to central dopamine pathways as well as dopamine receptors and dopaminergic neurons in basal ganglia. Taken together, the studies reviewed provide a basis for understanding streptococcal sequelae and how immune responses against group A streptococci influence autoimmunity and inflammatory responses in the heart and brain.

Brain human monoclonal autoantibody from sydenham chorea targets dopaminergic neurons in transgenic mice and signals dopamine D2 receptor: implications in human disease

How autoantibodies target the brain and lead to disease in disorders such as Sydenham chorea (SC) is not known. SC is characterized by autoantibodies against the brain and is the main neurologic manifestation of streptococcal-induced rheumatic fever. Previously, our novel SC-derived mAb 24.3.1 was found to recognize streptococcal and brain Ags. To investigate in vivo targets of human mAb 24.3.1, VH/VL genes were expressed in B cells of transgenic (Tg) mice as functional chimeric human VH 24.3.1-mouse C-region IgG1(a) autoantibody. Chimeric human-mouse IgG1(a) autoantibody colocalized with tyrosine hydroxylase in the basal ganglia within dopaminergic neurons in vivo in VH 24.3.1 Tg mice. Both human mAb 24.3.1 and IgG1(a) in Tg sera were found to react with human dopamine D2 receptor (D2R). Reactivity of chorea-derived mAb 24.3.1 or SC IgG with D2R was confirmed by dose-dependent inhibitory signaling of D2R as a potential consequence of targeting dopaminergic neurons, reaction with surface-exposed FLAG epitope-tagged D2R, and blocking of Ab reactivity by an extracellular D2R peptide. IgG from SC and a related subset of streptococcal-associated behavioral disorders called "pediatric autoimmune neuropsychiatric disorder associated with streptococci" (PANDAS) with small choreiform movements reacted in ELISA with D2R. Reaction with FLAG-tagged D2R distinguished SC from PANDAS, whereas sera from both SC and PANDAS induced inhibitory signaling of D2R on transfected cells comparably to dopamine. In this study, we define a mechanism by which the brain may be altered by Ab in movement and behavioral disorders.

Synthesis and immunological activity of an oligosaccharide-conjugate as a vaccine candidate against Group A Streptococcus

The synthesis and immunogenicity of a tetanus toxoid (TT)-conjugate of the hexasaccharide portion of the cell-wall polysaccharide (CWPS) of the Group A Streptococcus (GAS) is described. The synthesis relies on the reaction of an allyl glycoside of the hexasaccharide with cysteamine, followed by the reaction of the resultant amine with diethyl squarate to give the monoethyl squarate adduct. Subsequent reaction with the lysine ε-amino groups on TT gives the glycoconjugate containing 30 hexasaccharide haptens per TT molecule. The immunogenicity in mice is similar to that obtained with a native CWPS-TT conjugate, validating the glycoconjugate as a vaccine candidate against GAS infections.

Autoimmune myocarditis, valvulitis, and cardiomyopathy

Myocarditis and valvulitis are inflammatory diseases affecting myocardium and valve. Myocarditis, a viral-induced disease of myocardium, may lead to dilated cardiomyopathy and loss of heart function. Valvulitis leads to deformed heart valves and altered blood flow in rheumatic heart disease. Animal models recapitulating these diseases are important in understanding the human condition. Cardiac myosin is a major autoantigen in heart, and antibodies and T cells to cardiac myosin are evident in inflammatory heart diseases. This unit is a practical guide to induction and evaluation of experimental autoimmune myocarditis (EAM) in several mouse strains and the Lewis rat. Purification protocols for cardiac myosin and protocols for induction of EAM by cardiac myosin and its myocarditis-producing peptides, and coxsackievirus CVB3, are defined. Protocols for assessment of myocarditis and valvulitis in humans and animal models provide methods to define functional autoantibodies targeting cardiac myosin, β-adrenergic, and muscarinic receptors, and their deposition in tissues.

What every psychiatrist should know about PANDAS: a review

The term Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcus infections (PANDAS) was coined by Swedo et al. in 1998 to describe a subset of childhood obsessive-compulsive disorders (OCD) and tic disorders triggered by group-A beta-hemolytic Streptococcus pyogenes infection. Like adult OCD, PANDAS is associated with basal ganglia dysfunction. Other putative pathogenetic mechanisms of PANDAS include molecular mimicry and autoimmune-mediated altered neuronal signaling, involving calcium-calmodulin dependent protein (CaM) kinase II activity. Nonetheless the contrasting results from numerous studies provide no consensus on whether PANDAS should be considered as a specific nosological entity or simply a useful research framework. Herein we discuss available data that could provide insight into pathophysiology of adult OCD, or might explain cases of treatment-resistance. We also review the latest research findings on diagnostic and treatment.

Doubly branched hexasaccharide epitope on the cell wall polysaccharide of group A streptococci recognized by human and rabbit antisera

A number of epitope specificities associated with the cell wall polysaccharide antigen of group A streptococci were identified in a polyclonal rabbit antiserum induced in rabbits by whole group A streptococci and in polyclonal convalescent human antisera from children that had recovered from streptococcal A infections. The identification was achieved by using a series of synthetic oligosaccharides, glycoconjugates, and bacterial polysaccharide inhibitors to inhibit the binding of the group A helical polysaccharide to the polyclonal antisera. The exclusively dominant epitope expressed in the convalescent human antisera was the doubly branched extended helical hexasaccharide with the structure alpha-L-Rhap(1-->2)[beta-D-GlcpNAc(1-->3)]alpha-L-Rhap(1-->3)alpha-L-Rhap(1-->2)[beta-D-GlcpNAc(1-->3)]alpha-L-Rhap. The hexasaccharide epitope also bound with the highest immunoreactivity to the rabbit antiserum. In contrast, the human antisera did not show significant binding to the singly branched pentasaccharide with the structure alpha-L-Rhap(1-->2)alpha-L-Rhap(1-->3)alpha-L-Rhap(1-->2)[beta-D-GlcpNAc(1-->3)]alpha-L-Rhap or the branched trisaccharide alpha-L-Rhap(1-->2)[beta-D-GlcpNAc(1-->3)]alpha-l-Rhap, although both these haptens bound significantly to the same rabbit antiserum, albeit with less immunoreactivity than the hexasaccharide. Inhibition studies using streptococcal group A and B rabbit antisera and the inhibitors indicated above also suggested that the group A carbohydrate, unlike the group B streptococcal polysaccharide, does not contain the disaccharide alpha-L-Rhap(1-->2)alpha-L-Rhap motif at its nonreducing chain terminus, stressing the importance of mapping the determinant specificities of these two important streptococcal subcapsular group polysaccharides to fully understand the serological relationships between group A and group B streptococci.

Selective depletion of Vbeta2+CD8+ T cells in peripheral blood from rheumatic heart disease patients

Acute rheumatic fever (ARF) and its chronic valvular sequelae are the delayed consequence of a pharyngeal infection with group A Streptococcus (GAS). Several GAS proteins have been shown to be superantigens, raising the possibility that the expansion or deletion of T cells expressing specific Vbeta regions might play a role in the pathogenesis of ARF or chronic rheumatic heart disease (RHD). We therefore analyzed by four-color flow cytometry, the Vbeta repertoire on CD3, CD4 and CD8 T cells from four ARF patients, 10 RHD patients and also nine healthy controls. A selective depletion of Vbeta2+ T cells was found only in the CD8 subset of chronic RHD patients. This is of interest since a number of GAS superantigens exert their effects on Vbeta2+ cells and because only CD8+ T cells from ARF and RHD patients undergo anergy in response to GAS superantigens. Our results suggests that an ongoing immune process is present in RHD patients and that CD8+ T cells may have an important immunoregulatory role in the pathogenesis of the disease.

Saturation transfer difference 1D-TOCSY experiments to map the topography of oligosaccharides recognized by a monoclonal antibody directed against the cell-wall polysaccharide of group A streptococcus

A new saturation transfer difference 1D-TOCSY NMR experiment that allows the investigation of complex ligands interacting with proteins and its application in the mapping of which portions of oligosaccharide ligands (epitope) interact with a complementary antibody are described. The interaction between trisaccharide and hexasaccharide ligands, corresponding to fragments of the cell-wall polysaccharide of Streptococcus Group A, and a monoclonal antibody directed against the polysaccharide is investigated at the molecular level. The polysaccharide consists of alternating alpha-(1-->2) and alpha-(1-->3) linked L-rhamnopyranose (Rha) residues with branching N-acetyl-D-glucopyranosylamine (GlcNAc) residues linked beta-(1-->3) to alternate rhamnopyranose rings. The epitope is proven to consist not only of the immunodominant GlcNAc sugar but also of an entire branched trisaccharide repeating unit. The experimental NMR data serve to check and validate the computed models of the oligosaccharide-antibody complexes.

Restriction in the usage of variable beta regions in T-cells infiltrating valvular tissue from rheumatic heart disease patients

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's cardiac tissues. Several GAS proteins have been reported to be superantigens, also raising the possibility that T cells in RHD could be driven by superantigens. We therefore analysed the variable beta (V beta) repertoire of T cells infiltrating heart valves from chronic RHD patients undergoing elective valvular surgery. We analysed 15 valve specimens from patients with longstanding quiescent RHD and control valves from four non-rheumatic individuals. Total RNA was extracted from fresh valve tissue and employed to amplify 22 V beta genes by RT-PCR. In valvular tissue, a restricted number of only 2 to 9 V beta regions were detected as opposed to the findings in control valves. In 8 RHD valves, the expression of V beta1, 2, 3, 5.1, 7, 8, 9 or 14 was marked. These V beta regions have been related to GAS superantigens. Our results evidence the presence of a restricted set of T lymphocytes in valvular tissue from a majority of patients with chronic RHD and suggest that valvular sequelae in these patients might be related to a local antigen or superantigen driven inflammatory process that persists even many years after the initial triggering event.

Synthesis and conformational analysis of a pentasaccharide corresponding to the cell-wall polysaccharide of the Group A Streptococcus

The synthesis and conformational analysis of a pentasaccharide corresponding to a fragment of the cell-wall polysaccharide (CWPS) of the bacteria Streptococcus Group A are described. The polysaccharide consists of alternating alpha-(1 --> 2)- and alpha-(1 --> 3)-linked L-rhamnopyranose (Rhap) residues with branching 2-acetamido-2-deoxy-D-glucopyranose (GlcpNAc) residues linked beta-(1 --> 3) to alternate rhamnose rings. The pentasaccharide is of interest as a possible terminal unit on the CWPS, for use in a vaccine. The syntheses employed a trichloroacetimidate glycosyl donor. Molecular dynamics (MD) calculations of the pentasaccharide with the force fields CVFF and PARM22, both in gas phase and with explicit water present, gave different predictions for the flexibility and preferred conformational space. Metropolis Monte Carlo (MMC) calculations with the HSEA force field were also performed. Experimental data were obtained from 1D transient NOE measurements. Complete build-up curves were compared to those obtained by full relaxation matrix calculations in order to derive a model of the conformation. Overall, the best fit between experimental and calculated data was obtained with MMC simulations using the HSEA force field. Molecular dynamics and MMC simulations of a tetrasaccharide corresponding to the Group A-variant polysaccharide, which differs in structure from Group A in lacking the GlcpNAc residues, were also performed for purposes of comparison.

Rheumatic disorders associated with streptococcal infections

The proteins in the cell wall of Streptococcus have many functions, with some proteins being regarded as a marker of their rheumatological potential. High levels of antibodies directed against some proteins are seen in patients with acute rheumatic fever. The theory of molecular mimicry forms the basis of the relationship between the bacteria and the disease acute rheumatic fever. A distinct entity which does not fulfil Jones' criteria, and which is known as post-streptococcal reactive arthritis following infection with beta-haemolytic streptococci, is being encountered more frequently. A pyogenic form of arthritis due to Streptococcus is one of the most common and serious joint infections and requires prompt recognition and treatment.

Autoantibodies in the sera of patients with rheumatic heart disease: characterization of myocardial antigens by two-dimensional immunoblotting and N-terminal sequence analysis

The concept of antigenic mimicry in autoimmune diseases such as rheumatic fever has been under investigation for decades and the range of cross-reactive tissue antigens for streptococcal-induced antibodies identified in rheumatic heart disease is still expanding. To identify heart tissue-reactive antigens which may be implicated in the secondary immunopathogenesis of rheumatic fever, sera from 56 patients with acute rheumatic heart disease were probed in two-dimensional Western blots for reactivity against heart tissue antigens. After two-dimensional immunoblot analysis, proteins were submitted to N-terminal amino acid sequence analysis. This analysis identified creatine kinase, two mitochondrial proteins and, at a low level, various stress proteins as cross-reactive myocardial antigens. Therefore, in addition to myosin, creatine kinase may represent another major antigen for autoreactive antibodies in rheumatic heart disease. Mitochondrial proteins have been implicated in the pathogenesis of inflammatory heart disease for some years, and in this study we have identified two mitochondrial proteins as relevant antigens in rheumatic heart disease.

[D8/17 marker: implication to neuropsychiatry]

Recent studies suggest that there is a relationship between rheumatic fever (RF) and some neuropsychiatric disorders. Thus, it has been thought that autoimmune mechanisms might be related to the etiology of these neuropsychiatric disorders. It has also been demonstrated that a B cell alloantigen associated to RF is also abnormally overexpressed in patients with such neuropsychiatric disorders. This alloantigen is recognised by a monoclonal antibody known as D8/17. The aim of this article is to introduce the recent work done about D8/17 and its possible implications to the study of neuropsychiatric disorders related or not to RF.

Autoimmune mechanisms in movement disorders

A number of disorders, including childhood-onset obsessive compulsive disorder (OCD) and Gilles de la Tourette's syndrome (TS), are known to be neurobiological in nature. Both TS and OCD are neuropsychiatric diagnoses that involve congitive and perceptual dysfunction in addition to motor and psychiatric manifestations. The association of the B-cell marker with both Sydenham's chorea and a group of neuropsychiatric disorders, such as OCD, tics, and TS, has been useful as a marker in these diseases. This evidence, coupled with the recent finding of anti-brain antibodies in the sera of these patients, raises a number of interesting questions concerning the pathological mechanisms involved in these diseases. Thus, further molecular characterization of the brain and streptococcal antigens will be crucial to our understanding of the neurophysiological processes involved in these disorders.

Bivalency and epitope specificity of a high-affinity IgG3 monoclonal antibody to the Streptococcus group A carbohydrate antigen. Molecular modeling of a Fv fragment

The binding of Strep 9, a mouse monoclonal antibody (mAb) of the IgG3 subclass directed against the cell-wall polysaccharide of Group A Streptococcus (GAS), has been characterized. The intact antibody and proteolytic fragments of Strep 9 bind differently to GAS: the intact mAb and F(ab)2' have greater affinity for the carbohydrate epitope than the monomeric Fab or F(ab)'. A mode of binding in which Strep 9 binds bivalently to portions of the polysaccharide on adjacent chains on GAS is proposed. A competitive ELISA protocol using a panel of carbohydrate inhibitors shows that the branched trisaccharide, beta-D-GlcpNAc-(1-->3)-[alpha-L-Rhap-(1-->2)]-alpha-L-Rhap, and an extended surface are key components of the epitope recognized by Strep 9. Microcalorimetry measurements with the mAb and two synthetic haptens, a tetrasaccharide and a hexasaccharide, show enthalpy-entropy compensation as seen in other oligosaccharide-protein interactions. Molecular modeling of the antibody variable region by homology modeling techniques indicates a groove-shaped combining site that can readily accommodate extended surfaces. Visual docking of an oligosaccharide corresponding to the cell-wall polysaccharide into the site provides a putative model for the complex, in which a heptasaccharide unit occupies the site and the GlcpNAc residues of two adjacent branched trisaccharide units occupy binding pockets within the groove-shaped binding site.

Therapeutic plasma exchange and intravenous immunoglobulin for obsessive-compulsive disorder and tic disorders in childhood

BACKGROUND

In children, exacerbations of tics and obsessive symptoms may occur after infection with group A beta-haemolytic streptococci. If post-streptococcal autoimmunity is the cause of the exacerbations, then children might respond to immunomodulatory treatments such as plasma exchange or intravenous immunoglobulin (IVIG). We studied whether plasma exchange or IVIG would be better than placebo (sham IVIG) in reducing severity of neuropsychiatric symptoms.

METHODS

Children with severe, infection-triggered exacerbations of obsessive-compulsive disorder (OCD) or tic disorders, including Tourette syndrome, were randomly assigned treatment with plasma exchange (five single-volume exchanges over 2 weeks), IVIG (1 g/kg daily on 2 consecutive days), or placebo (saline solution given in the same manner as IVIG). Symptom severity was rated at baseline, and at 1 month and 12 months after treatment by use of standard assessment scales for OCD, tics, anxiety, depression, and global function.

FINDINGS

30 children entered the study and 29 completed the trial. Ten received plasma exchange, nine IVIG, and ten placebo. At 1 month, the IVIG and plasma exchange groups showed striking improvements in obsessive-compulsive symptoms (mean improvement on children's Yale-Brown obsessive compulsive scale score of 12 [45%] and 13 [58%], respectively), anxiety (2.1 [31%] and 3.0 [47%] improvement on National Institute of Mental Health anxiety scale), and overall functioning (2.9 [33%] and 2.8 [35%] improvement on National Institute of Mental Health global scale). Tic symptoms were also significantly improved by plasma exchange (mean change on Tourette syndrome unified rating scale of 49%). Treatment gains were maintained at 1 year, with 14 (82%) of 17 children "much" or "very much" improved over baseline (seven of eight for plasma exchange, seven of nine for IVIG).

INTERPRETATION

Plasma exchange and IVIG were both effective in lessening of symptom severity for children with infection-triggered OCD and tic disorders. Further studies are needed to determine the active mechanism of these interventions, and to determine which children with OCD and tic disorders will benefit from immunomodulatory therapies.

Antineuronal antibodies in rheumatic chorea

The objectives of our study were to examine the sera of rheumatic chorea (RhCh) patients (those with acute or chronic RhCh or with a past history of RhCh) for the presence of antineuronal antibodies (ANeurA) and to correlate the results with disease activity, chronicity, and the number and durations of choreic attacks. Subjects were inpatients of the Pediatric Hospital, Ain Shams University, and outpatients of the Outpatient Pediatric Cardiology Clinic (both in Cairo, Egypt). Forty children with RhCh (mean age, 10.9 years) and 40 healthy controls were tested. An indirect-immunofluorescence technique was used for the detection of ANeurA. ANeurA were present in the sera of 100, 93, and 44% of the patients with acute, chronic, and past histories of RhCh, respectively. A definition of chronic chorea is presented for the first time. None of the control subjects had ANeurA in their sera. The presence of ANeurA correlated with disease activity. A statistically significant increase (P < 0.01) in the prevalence of ANeurA was found for patients with active chorea (acute and chronic) compared with the prevalence in patients with past histories of RhCh (controlled chorea). ANeurA were present in the sera of both patients with acute RhCh and patients with chronic RhCh, yet patients with acute RhCh showed more brightness and cell staining than chronic patients. The severity, number, and duration of each attack were not related to the presence of ANeurA. These results strengthen further the concept of autoimmunity being the basis for the pathogenesis of RhCh. The presence of ANeurA correlated with the activity of RhCh but not with the severity, number, or duration of attacks. Humoral immunity definitely plays a role in RhCh; thus, routine administration of corticosteroids to patients with acute RhCh is suggested to prevent neuron damage and chronicity. The chronicity of chorea is not due to a further increase in ANeurA but is probably due to sensitivity to these antibodies.

The arthritogenic properties of microbial antigens. Their implications in disease states

The sharing of antigenic determinants between host and microbe is a common event and new microbial-tissue cross-reactions are being recognized each year. Almost every human organ has been implicated as a possible target. The purpose of this article is to examine the arthritogenic properties of these microbial antigens and to explore the mechanisms by which they induce pathologic damage and disease.

Rheumatic fever. The relationships between host, microbe, and genetics

Acute rheumatic fever is a delayed, nonsuppurative sequela of a pharyngeal infection with the group A streptococcus. The onset of the disease is usually characterized by an acute febrile illness; however, there may be chronic involvement of the heart and/or central nervous system. The article explores the relationship between the initial infection and host-microbial interactions that may be operative in disease pathogenesis.

Preferential recognition of human myocardial antigens by T lymphocytes from rheumatic heart disease patients

Acute rheumatic fever (ARF) and rheumatic heart disease (RHD) are autoimmune sequelae of upper respiratory infections with group A streptococci (GAS). To gain a better understanding of the pathogenesis of these diseases, we examined the in vitro proliferative responses of peripheral blood mononuclear cells (PBMC) from RHD patients to human myocardial proteins in a T-cell Western assay. A number of myocardial proteins fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis were recognized by PBMC from both patients and controls. However, PBMC from a significant percentage of RHD patients (40%) responded to a discrete band of myocardial proteins migrating with an apparent molecular mass of 50 to 54 kDa while none of the control subject PBMC responded to this protein band (P < or = 0.0001). To further investigate the link between infections with GAS and autoimmune carditis, we studied the proliferative responses of PBMC from patients and controls to myocardial proteins before and after in vitro stimulation of the cells with opsonized GAS isolated from ARF patients. Priming of PBMC with rheumatogenic GAS caused the percentage of RHD patients responding to the 50- to 54-kDa myocardial proteins to increase from 43 to 90% (P < or = 0.0284). By contrast, PBMC from control subjects failed to recognize the 50- to 54-kDa myocardial proteins even after stimulation with the opsonized streptococci (P < or = 0.0001). The assay sensitivity was increased from 40 to 90% after priming of a patient's cells with opsonized GAS, but the positive predictive value was 100% in both unprimed and primed cultures. Antibodies generated to partially purified 50- to 54-kDa myocardial proteins did not cross-react with either streptococcal homogenates, purified M protein, myosin, laminin, or vimentin, suggesting a lack of cross-reactivity at the humoral level. This study suggests that the 50- to 54-kDa myocardial proteins contain a putative antigen that is preferentially recognized by T cells from RHD patients and demonstrates that exposure to streptococcal antigens enhances the ability of patients to recognize these proteins.

Antibodies in the sera of acute rheumatic fever patients bind to human cardiac tropomyosin

Previous work from this laboratory has demonstrated the occurrence of heart reactive antibodies (HRA) in the sera of acute rheumatic fever (ARF) patients which bound primarily to the sarcolemmal sheath of cardiac myofibres. While many investigators have reported the presence of antibodies to myosin in the sera of ARF patients, the question of whether these sera also contain antibodies to other cytoskeletal proteins has not been addressed. In this study, crude human sarcolemmal sheaths were extracted with 3 M KCl and partially purified using a DEAE cellulose column and a step gradient of NaCl. Maximum reactivity with ARF sera was seen with a protein fraction eluted with 0.3 M NaCl. Using FPLC, a single polypeptide of 38 kDa reacted in ELISA preferentially with ARF sera when compared to sera from patients with uncomplicated streptococcal infections and acute post-streptococcal glomerulonephritis (APSGN). A comparison of the N-terminal sequence of the purified protein and competitive inhibition assays indicated that the reactive sarcolemmal antigen was human cardiac tropomyosin.

Antigenic specificity of lymphocytes isolated from valvular specimens of rheumatic fever patients

T cell lines were established from both valvular specimens and peripheral blood lymphocytes from seven patients with well documented rheumatic heart disease. These cell lines were stimulated with either PHA or streptococcal antigens. Proliferation assays revealed that both valvular and peripheral blood T cell lines reacted to cell wall (CW) and cell membrane (CM) antigens obtained from rheumatic fever associated group A streptococci and not to nephritogenic strains. None of the cell lines reacted to M protein, myosin or other mammalian cytoskeletal proteins. The unique reactivity of rheumatic fever T cell lines only to cellular structures obtained from rheumatogenic strains suggests that these lines react to epitopes specific for antigens obtained from these strains.

HLA class II antigens in rheumatic fever. Analysis of the DR locus by restriction fragment-length polymorphism and oligotyping

We recently described an association of serologically defined HLA class II antigens DR7 and DR53 with RF. This study aimed at determining more precisely the class II gene associated with the disease. We studied patients and age- and race-matched controls. Genomic DNA was digested with four different enzymes and hybridized with HLA cDNA probes for DR beta, DQ beta, DQ alpha, and DP beta genes. RFLP analysis disclosed a fragment of 13,81 kb on Taq I DR beta blots, which correlates with HLA-DR53 and HLA-DR16, according to data from the Tenth International Histocompatibility Workshop. Of 24 patients, 20 (83.3%), were positive for the 13.81-kb/Taq I/DR beta allogenotope, compared with 16 (34%) of 47 healthy individuals (p = 0.000079, Fisher's exact test). Search for specific nucleotide sequences was performed using polymerase chain reaction technique. Oligonucleotides corresponding either to allele-specific DR7 and DR53 sequences, or shared by DRB1 and DRB3, DRB4, or DRB5 sequences were screened. Differences were tested throughout the second exon up to codon 100. Results were as expected by simple comparison with the published sequences of individual alleles. Although a clear association with DRB loci is shown, a susceptibility associated either with an allele or with a unique sequence was not found. A promiscuous presentation of the putative cross-reacting peptide or a heterogeneity of the causative agent might be the origin of these results. Genetic complementarity may be an additional factor defining inherited susceptibility to this disease.

Beta haemolytic streptococci and reactive arthritis in adults

There is an increasing occurrence of reactive group A beta haemolytic streptococci (BHS) phenomena. This review makes a case for considering BHS in the differential diagnosis of adult reactive arthritis. This is based on (a) published reports over the past 45 years describing first attacks of rheumatic fever in adults; (b) the longstanding observation that polyarthritis is the most commonly expressed Jones major criterion in adults; (c) the broad spectrum of clinical expression of disease following streptococcal infection, with the re-emergence of the term 'poststreptococcal reactive arthritis'. The arthritis in adult rheumatic fever is characterised by sequential involvement of large weightbearing joints. Recurrent, severe, prolonged arthritis has been a prominent feature of adult poststreptococcal reactive arthritis. Carditis has been reported in 33% of adult patients with rheumatic fever. Consequently long term antibiotic prophylaxis for adults with reactive BHS phenomena should be strongly considered, and guidelines are suggested for this in individual patients. Further areas for research are discussed, particularly the interrelations between bacteria and host in disease expression, and the possibility that BHS might play a part in chronic arthritides and vasculitides.

Enhancement of IL-1, IL-2 production and IL-2 receptor generation in patients with acute rheumatic fever and active rheumatic heart disease; a prospective study

In a prospective study, patients with quiescent rheumatic heart disease (CRHD), streptococcal pharyngitis (SP) and healthy normal subjects produced comparable amounts of IL-1 and IL-2, but acute rheumatic fever (ARF) patients produced significantly elevated amounts of IL-1 and IL-2 at all intervals up to 48 weeks. In active rheumatic heart disease (ARHD), IL-1 activity returned to within normal range at 48 weeks, but IL-2 activity remained persistently elevated compared with CRHD, SP and healthy age- and sex-matched volunteers. CD4+ T lymphocytes were significantly increased in the peripheral blood of ARF and ARHD patients. The amount of IL-2 produced by ARF and ARHD patients correlated with the percentage of helper T lymphocytes (CD4+ cells) but not with the percentage of suppressor/cytotoxic T lymphocytes (CD8+ cells). Moreover, pre- and post-phytohaemagglutinin (PHA)-stimulated peripheral blood mononuclear cell (PBMC) cultures from ARF and ARHD patients contained higher proportions of IL-2R+ (CD25+) cells than those from patients with SP, CRHD and normal individuals, which persisted up to 48 weeks. The percentage of CD25+ cells in both types of PBMC cultures directly correlated with the percentage of CD4+ cells and not with CD8+ cells in active rheumatic patients only. These findings indicate that the immune response in ARF and ARHD patients is skewed to produce activated helper T cells that release IL-2 which drives the accumulation of more T helper cells. The result is an undamped helper T cell response in the peripheral blood of these patients.

Bacterium-induced autoimmune reactivity

Evidence is growing that autoimmune reactivity results from a combination of endogenous (e.g. MHC type) and environmental factors. Our experimental study focuses on the induction of autoimmune reactivity by microbial factors. Splenic formation and serum levels of anti-erythrocyte antibodies and circulating immune complexes were taken as parameters. It was found that experimental infection of mice with Escherichia coli and Salmonella typhimurium was accompanied by clear signs of autoimmune reactivity, smooth bacteria being almost ten times as potent as rough mutant strains. An attempt was made to correlate the data obtained with live bacteria to their corresponding endotoxins. It was concluded that the induction of more prominent autoimmune reactivity by smooth bacteria must be ascribed to a longer survival time in vivo. Our data support the view that bacterium-derived factors are involved in the etiology (and possibly also the course) of autoimmune diseases.

Abnormal fibroblast clone--an alternative hypothesis for pathogenesis of rheumatic heart disease

Fibrosis is an ubiquitous process. Any tissue injury can culminate in fibroblast accumulation and multiplication with collagen synthesis and deposition. A large number of chronic disease states such as rheumatic heart disease, constrictive pericarditis, cirrhosis of the liver, renal interstitial fibrosis, chronic interstitial lung disease are characterized by extensive fibrosis. In many of these patients, when there is no clinical or laboratory evidence of previous injury, it is presumed that the initiating insult/injury had been 'subclinical'. I propose that 1) the fibroblasts can be activated even in the absence of preceding inflammation, 2) it is the type of 'fibroblast clone' in a given individual together with the 'milieu' in a particular tissue/organ which decides the occurrence and severity of subsequent fibrosis. This fibroblast clonal theory adds a new dimension to the pathogenesis of various disease states and may help in identifying those at high-risk and in evolving a unified therapeutic strategy for amelioration of various disorders characterized by extensive fibrosis.

HLA and rheumatic fever in Turkish Children

We report the results of research on human leukocyte allo-antigen (HLA) and rheumatic fever (RF), the first published study to be carried out among Turkish children with RF. Ninety-three Turkish children, aged between 6 and 16 years (mean: 8 +/- 2.6), with RF participated in the study. Of the total, 26 patients had their first attack and 39 had acute rheumatic activity at the time of registration. The results demonstrate (1) negative but not significant association between HLA-A2 and RF; (2) a positive association between HLA-DR4 and RF (p less than 0.001); (3) a significant association between HLA-DR4 and carditis, but not with isolated arthritis. These results corroborate the concept of race-specific genetically determined familial susceptibility to the development of rheumatic heart disease.

Immunochemical characterization of polyclonal and monoclonal Streptococcus group A antibodies by chemically defined glycoconjugates and synthetic oligosaccharides

Synthetic oligosaccharides of increasing complexity that represent different epitopes of the Streptococcus Group A cell-wall polysaccharide were used as haptens and glycoconjugates of bovine serum albumin (BSA) and horse hemoglobin (HHb) to characterize polyclonal and monoclonal antibodies. Rabbits were immunized with the BSA glycoconjugates of a linear trisaccharide, branched trisaccharide, and branched pentasaccharide. The binding specificities of the polyclonal antisera were determined by a series of inhibition ELISA studies in which disaccharide through pentasaccharide haptens were used as inhibitors of antibody-glycoconjugate binding. Monoclonal antibodies derived from mice immunized with a killed bacterial vaccine were selected for their binding to native polysaccharide antigen coupled to BSA and the BSA glycoconjugates of the di- and linear tri-saccharides. Polyclonal antibodies were moderately specific for the oligosaccharide epitope of the immunizing glycoconjugate and only those antibodies raised to the branched pentasaccharide antigen showed cross-reaction with the bacterial antigen. The behaviour of selected monoclonal antibodies parallels the binding profile of polyclonal antibodies in that the two highest-titre antibodies were directed toward an epitope displayed by the branched pentasaccharide.

Convergent synthesis of higher-order oligosaccharides corresponding to the cell-wall polysaccharide of the beta-hemolytic Streptococci group A. A branched hexasaccharide hapten

A convergent synthesis of a hexasaccharide corresponding to the cell-wall polysaccharide of the beta-hemolytic Streptococci Group A is described. The strategy relies on the preparation of a key branched trisaccharide unit alpha-L-Rhap-(1----2)-[beta-D-GlcpNAc-(1----3)]-alpha-L-Rhap which functions both as a glycosyl acceptor and donor. The hexasaccharide is obtained after only three glycosylation reactions. This fully functionalized unit can serve, in turn, as a glycosyl acceptor or donor for the synthesis of higher-order structures. Deprotection gives a hexasaccharide for use as a hapten in immunochemical studies. The characterization of all compounds by high resolution 1H- and 13C-n.m.r. spectroscopy is also described.

Adherence of Streptococcus pyogenes M type 5 to pharyngeal and buccal cells of patients with rheumatic fever and rheumatic heart disease during a one-year follow-up

In vitro adherence of Streptococcus pyogenes M type 5 to isolated pharyngeal and buccal epithelial cells was studied in patients with acute recurrent rheumatic fever (n = 21), chronic rheumatic heart disease (n = 33), streptococcal pharyngitis (n = 12), and in normal controls. Patients were investigated at admission and one, six and 12 months later. Streptococci adhered significantly more to the pharyngeal cells of patients with rheumatic fever and rheumatic heart disease than to the pharyngeal cells of controls. Adherence of streptococci to pharyngeal cells of patients with pharyngitis was not different from age-matched controls. The adherence of streptococci to the pharyngeal cells of patients with acute rheumatic fever fell during follow-up but even after one year remained significantly higher than in the control group. These findings suggest that host factor(s) controlling streptococcal adhesion and colonization at the pharyngeal mucosa may be important in the pathogenesis of acute rheumatic fever.

Cytotoxic and viral neutralizing antibodies crossreact with streptococcal M protein, enteroviruses, and human cardiac myosin

The development of autoimmunity in certain instances is related to infectious agents. In this report, cytotoxic monoclonal antibodies (mAbs) that recognize epitopes on both enteroviruses and the bacterium Streptococcus pyogenes are described. Murine anti-streptococcal mAbs that were crossreactive with streptococcal M protein, human cardiac myosin, and other alpha-helical coiled-coil molecules were found to neutralize coxsackieviruses B3 and B4 or poliovirus type 1. The viral-neutralizing anti-streptococcal mAbs were also cytotoxic for heart and fibroblast cell lines and reacted with viral capsid proteins on a Western immunoblot. Alignment of amino acid sequences shared between streptococcal M protein, coxsackie-virus B3 capsid protein VP1, and myosin revealed 40% identity in a 14- to 15-amino acid overlap. Synthetic peptides containing these sequences blocked mAb reactivity with streptococcal M protein. The data show that antibodies against alpha-helical structures of bacterial and viral antigens can lead to cytotoxic reactions and may be one mechanism to explain the origin of autoimmune heart disease.

Frequency of D8/17 B lymphocyte alloantigen in north Indian patients with rheumatic heart disease

Ninety patients with rheumatic heart disease and 50 age- and sex-matched healthy human volunteers representing a North Indian population were typed for the B cell alloantigen D8/17 using a monoclonal antibody and a single step immunofluorescence technique. This alloantigen was expressed in 66.44% patients with RHD as compared with 14% of the normal population. A high relative risk (RR = 11.13) indicated a strong association of D8/17 B cell alloantigen with rheumatic heart disease. Increase in the frequency of the marker was observed with increasing age up to the fifth decade (40-49 years) in these patients. However, the frequency of this alloantigen, in the present study, in North Indian patients with rheumatic heart disease is lower than that reported in the American population.

Acute rheumatic fever during childhood in Saudi Arabia

During a 5-year period ending in December 1989, 73 episodes of acute rheumatic fever in 67 children aged 4-14 years were prospectively studied to ascertain the clinical profile of the disease in initial attacks and recurrences, and to compare the findings with those from other countries. Among 51 children with a first episode of acute rheumatic fever, 76% had arthritis and 43% had carditis. In 22 children with recurrences, arthritis was present in 45% and carditis in 91%. Carditis was more severe among the cases with recurrences. Mitral insufficiency was the most common valvular lesion, but no case of mitral stenosis was detected. Chorea, subcutaneous nodules, and Erythema marginatum were relatively rare. The demographic, clinical and laboratory findings of this study resemble those from Western countries, in contrast with data from tropical countries. Efforts aimed at prompt recognition and adequate treatment of streptococcal pharyngitis and maintenance of anti-streptococcal chemoprophylaxis would be rewarding in reducing the incidence of this disease and its sequelae.

Streptococcal cell wall arthritis. Passive transfer of disease with a T cell line and crossreactivity of streptococcal cell wall antigens with Mycobacterium tuberculosis

Primary lymph node cells derived from streptococcal cell wall arthritic rats or those derived from adjuvant arthritic rats proliferated in response to cell wall antigens derived from either streptococcal cell walls or those from M. tuberculosis. In addition, two T cell lines have been isolated from lymph nodes of rats during the chronic phase of streptococcal cell wall arthritis. These T cell lines transfered clinical disease to naive syngeneic irradiated recipients, and they proliferated in the presence of cell wall antigens derived from streptococci or antigens derived from Mycobacterium but failed to proliferate in the presence of the 65-kD antigen (containing the sequence TFGLQLELT) derived from Mycobacterium. These observations indicate that T cells play a crucial role in the pathogenesis of streptococcal cell wall arthritis and suggest that antigenic crossreactivity exists between cell walls of group A streptococci and antigens derived from Mycobacterium. The 65-kD Mycobacterium protein is not involved in the observed antigenic crossreactivity.

Identification of mononuclear cells and T cell subsets in rheumatic valvulitis

The composition of the mononuclear cellular filtrates was investigated in 13 valve specimens from nine patients with rheumatic carditis, some of whom had clinical and laboratory evidence of acute disease at the time of surgery. In acute valvulitis (AV) as well as in chronic active valvulitis (CAV), the cellular infiltrates were primarily composed of T cells and macrophages. In AV the majority of these T cells were of the helper phenotype (Leu 3a). The T cells subsets were more heterogeneous in CAV. In five valves, the helper T cells exceeded the number of suppressor T cells, whereas in three others, helper and cytotoxic/suppressor T cells were present in equal numbers. The HLA-DR antigen was expressed by the majority of the mononuclear cells and by the vascular endothelium. These findings indicate that the valvular injury may at least in part be mediated by delayed-type hypersensitivity mechanisms. Those cells comprising the Aschoff body were primarily positive for the HLA-DR and a novel monoclonal antibody called D8/17 which identifies an antigen known to be present on the B cells of rheumatic fever patients.