Long-term clopidogrel administration following severe coronary injury reduces proliferation and inflammation via inhibition of nuclear factor-kappaB and activator protein 1 activation in pigs

BACKGROUND

The optimal duration of clopidogrel treatment following percutaneous coronary intervention (PCI) and the patient population that would benefit most are still unknown. In a porcine coronary injury model, we tested two different durations of clopidogrel treatment on severely or moderately injured arteries and examined the arterial response to injury. To understand the molecular mechanism, we also investigated the effects on transcription factors nuclear factor-kappaB (NF-kappaB) and activator protein 1 (AP-1).

MATERIALS AND METHODS

In 24 cross-bred pigs, one coronary artery was only moderately injured by percutaneous transluminal coronary angioplasty (PTCA) and one coronary artery was severely injured by PTCA and subsequent beta-irradiation (Brachy group). Animals received 325 mg aspirin daily for 3 months and 75 mg clopidogrel daily for either 28 days [short-term (ST) clopidogrel group] or 3 months [long-term (LT) clopidogrel group].

RESULTS

After 3 months, the number of proliferating cells per cross-section differed significantly between ST and LT in both injury groups (PTCA(ST) 90.2 +/- 10.3 vs. PTCA(LT )19.2 +/- 4.7, P < 0.05; Brachy(ST) 35.8 +/- 8.4 vs. Brachy(LT) 7.5 +/- 2.0, P < 0.05). Similar results were seen for inflammatory cells (CD3(+) cells): PTCA(ST) 23.5 +/- 3.55 vs. PTCA(LT )4.67 +/- 0.92, P < 0.05; Brachy(ST) 83.17 +/- 11.17 vs. Brachy(LT) 20 +/- 4.82, P < 0.05). Long-term administration also reduced the activity of NF-kappaB and AP-1 by 62-64% and 42-58%, respectively. However, the effects of different durations of clopidogrel administration on artery dimensions were not statistically significant.

CONCLUSIONS

Regarding inflammation and transcription factor activity at the PCI site, long-term clopidogrel administration is superior to short-term administration, especially in severely injured arteries. Transferring our results to the human situation, patients with more severely diseased arteries may benefit from a prolonged clopidogrel medication after PCI.

[Increased thrombocyte activation in dilated cardiomyopathy: a risk factor for development of ventricular thrombosis despite anticoagulant therapy?]

HISTORY AND CLINICAL FINDINGS

A 48-year-old patient with dilated cardiomyopathy complained of dyspnea at rest, severe sleeplessness and a slight pain in the stomach. The clinical examination was normal except for a murmur at the apex of the heart. There was no evidence of edema or congestion of the jugular veins.

INVESTIGATION

The echocardiography demonstrated a dilated left ventricle with severely compromised function. No ventricular thrombi were present at this time. Coronary artery disease was excluded by coronary angiography. Endomyocardial biopsies were obtained from the right ventricular septum. The immunohistological analysis of the endomyocardial biopsy specimens revealed pathologically increased lymphocytic infiltrates and increased expression of interstitial and endothelial MHC I and II antigens. Flow cytometric analysis of platelets surface antigens (P-selectin, GP53, thrombospondin) was performed as a measure for intravasal platelet activation. Our patient compared to a healthy control group (> 4 SD) and to other patients with dilated cardiomyopathy (> 2 SD). A high grade increase of platelet activation was found.

TREATMENT AND COURSE

ACE inhibitor, diuretics, spironolactone and digitalis were used to treat the heart insufficiency. Due to the severe left ventricular dysfunction phenprocoumone and aspirin were also prescribed. A follow-up echocardiography was performed 6 months later. Comparable to the first examination left ventricular contractility was found to be severely reduced. In addition, a marginal thrombus was now present in the left ventricle despite antithrombotic therapy.

DISCUSSION

An increased platelet activation was found in the peripheral circulation of our patient with dilated cardiomyopathy. After 6 months, ventricular thrombi were found in the dilated ventricle, although aspirin and phenprocoumone had been administred. We speculate that an additional thrombotic treatment with clopidogrel is necessary in patients with dilated cardiomyopathy and increased platelet activation.

The possible role of myocardial biopsy in systemic sclerosis

The histopathological features of heart involvement in systemic sclerosis (SSc) are not widely known. In internal and transplantation medicine, myocardial biopsies are increasingly used to diagnose cardiomyopathies including myocarditis. In two SSc patients presenting with dyspnoea with no evidence of pulmonary involvement, the cause of the compromised heart function was sought by myocardial biopsy. Immunohistological analysis revealed an increased number of CD3+ + T cells indicating myocarditis in one, and increased amounts of fibroblasts in both SSc patients. The authors think that myocardial involvement in SSc should be differentially evaluated and they propose the use of myocardial biopsies as a tool to distinguish between inflammatory and fibrotic forms of heart involvement in SSc patients.

The shift in the myocardial adenine nucleotide translocator isoform expression pattern is associated with an enteroviral infection in the absence of an active T-cell dependent immune response in human inflammatory heart disease

OBJECTIVES

This study evaluates the relevance of an enteroviral infection and the intramyocardial T-cell immune response for the alteration in the adenine nucleotide translocator isoform transcription pattern (ANTitp) in patients suspected of having myocardial inflammation.

BACKGROUND

The ANT, the only mitochondrial carrier for ADP and ATP, plays a significant role in the energy metabolism and is involved in the apoptosis process. Its function and expression were found to be altered in the myocardium of patients with dilated cardiomyopathy and myocarditis.

METHODS

The ANTitp was analyzed in endomyocardial biopsies from 53 patients with clinically suspected inflammatory heart disease (csIHD). Enteroviral RNA was detected in the biopsies using the reverse transcripted polymerase chain reaction technique. The activation of the cellular immune system was assessed by the quantification of T-lymphocytes employing immunohistochemistry.

RESULTS

The ANTitp was found to be altered in 21 csIHD patients. Enteroviral genome was found in the heart of 71.4% of these patients, but only 37.5% of the patients with a normal ANTitp were virus-positive (p < 0.02). The infiltration with CD3+, CD45R0+ and CD8+ T-cells was substantially lower in myocardial specimens with an altered ANTitp than in biopsies with a normal ANTitp. Combining the data, an altered ANTitp was primarily found in virus-positive heart tissue, which was less infiltrated with lymphocytes or not at all.

CONCLUSIONS

An enteroviral infection is linked to changes in the ANT isoform expression in human heart tissue, which shows little or no evidence of an active T-cell dependent immune response. These results make a contribution to a better understanding of the pathophysiology of enterovirus-induced human inflammatory heart disease.

Enteroviral and immune mediated myocarditis in SCID mice

Severe combined immune deficiency (SCID) mice have been used as an animal model to study both the direct cytopathic effect of enteroviruses on the heart in the absence of an effective immune system and to investigate the role of immune mediated processes in the pathogenesis of human myocarditis. The infection of SCID mice with coxsackievirus B3 resulted in severe myocarditis with very high titers of the virus in the myocardium and severe necrosis of myocytes. This direct cytopathic effect caused an impairment of the myocardial function and resulted in a high mortality rate of the infected animals. For the study of the immune mechanisms in human myocarditis, peripheral blood leukocytes of patients with myocarditis, having an impaired left ventricular function without viral persistence in the myocardium, were transferred into SCID mice. As controls peripheral blood leukocytes of normal donors were used. At 60 days after transfer, human immunoglobulines could be demonstrated in the peripheral blood of the SCID mice, however, human autoantibodies against the adenine nucleotide translocator, a myocardial autoantigen, were only present in the animals receiving peripheral blood leukocytes from patients with myocarditis. Cellular infiltrates of human leukocytes in the myocardium and an impaired left ventricular function were also only observed in animals reconstituted with peripheral blood leukocytes from patients. These effects were T cell dependent as shown by differential transfer. These results are of interest for the treatment of human myocarditis, suggesting the avoidance of an immunosuppressive therapy in acute or chronic myocarditis with viral persistence to prevent a direct cytopathic effect in the absence of an effective immune system. However, in the setting of a chronic, (auto-)immunological myocarditis with the proven absence of entero- or adenoviral sequences an immunomodulatory therapy seems to be effective and safe.

Dilated cardiomyopathy is associated with significant changes in collagen type I/III ratio

BACKGROUND

It is controversial whether myocardial fibrosis in end-stage dilated cardiomyopathy (DCM) is associated with altered collagen type I/type III (Col I/Col III) ratio.

METHODS AND RESULTS

Patients with DCM (ejection fraction [EF] <50%, n=12) and with mild global left ventricular dysfunction (EF >50%, n=18) were examined. Col I, Col III, and transforming growth factors-beta1 (TGF-beta1) and -beta2 (TGF-beta2) gene expression in endomyocardial biopsies was evaluated by quantitative competitive reverse transcriptase-polymerase chain reaction (qRT-PCR). Collagen content was quantified after picrosirius red and immunohistological staining and by hydroxyproline assay. In patients with EF <50%, there was a pronounced 2- to 6-fold increase of myocardial Col I mRNA abundance (P<0.01), with a corresponding 1.6-fold increase at the protein level versus that found in patients with EF >50%. The Col III mRNA abundance showed a 2.0-fold increase (P<0.04). There was a relevant shift in the Col I/Col III mRNA ratio for DCM patients (Col I/Col III, 8.2) compared with patients with an EF >50% (Col I/Col III, 6. 4). In addition, total collagen content was increased in patients with EF <50% (n=3) (4.3+/-0.1%) compared with patients with EF >50% (n=8) (2.7+/-0.9%) (P<0.004). The biochemically determined ratio of hydroxyproline/total protein (n=12) was correlated to the Col I mRNA abundance (P<0.05, r=0.77). TGF-beta1 and TGF-beta2 showed elevated myocardial mRNA abundances (1- to 7-fold and 4- to 5-fold, respectively) in DCM patients.

CONCLUSIONS

Differential increase of Col I and Col III leads to an increased Col I/Col III ratio in DCM myocardium. Because Col I provides substantial tensile strength and stiffness, this may contribute to systolic and in particular diastolic dysfunction in DCM.

Detection of adenoviral genome in the myocardium of adult patients with idiopathic left ventricular dysfunction

BACKGROUND

The use of molecular biological techniques has demonstrated the importance of enteroviral infection of the myocardium in the pathogenesis of myocarditis and dilated cardiomyopathy in adults and adenovirus and enterovirus infection in children. The aim of this study was to determine the frequency of adenoviral infection of the myocardium of adults with impaired left ventricular function of unknown origin.

METHODS AND RESULTS

Nested polymerase chain reaction (nPCR) was used to determine the frequency of detection of adenoviral DNA and enteroviral RNA in myocardial tissue samples from 94 adult patients with idiopathic left ventricular dysfunction and 14 control patients. Histological and immunohistological analyses were performed to detect myocardial inflammation. Adenoviral genomic DNA was detected by nPCR in 12 of the 94 patients with left ventricular dysfunction (in each case, adenovirus type 2), whereas enteroviral RNA was detected in another 12 patients. All control samples were negative for both viruses. In all patients, active myocarditis was excluded according to the Dallas criteria. However, there was significantly decreased CD2, CD3, and CD45RO T lymphocyte counts in the adenovirus-positive group compared with the adenovirus-negative group (P<0.05), whereas no differences were associated with enterovirus infection.

CONCLUSIONS

Although enteroviruses are an important causative agent in the pathogenesis of myocarditis and dilated cardiomyopathy, this study shows that adenovirus infection is also important in the pathogenesis of left ventricular failure in adults. However, the pathogenetic basis of disease associated with adenovirus infection may be different than that after infection with other agents, particularly with respect to activation of the host immune response.

Enteroviral RNA replication in the myocardium of patients with left ventricular dysfunction and clinically suspected myocarditis

BACKGROUND

Previous studies dealing with the detection of enteroviral RNA in human endomyocardial biopsies have not differentiated between latent persistence of the enteroviral genome and active viral replication. Enteroviruses that are considered important factors for the development of myocarditis have a single-strand RNA genome of positive polarity that is transcribed by a virus-encoded RNA polymerase into a minus-strand mRNA during active viral replication. The synthesis of multiple copies of minus-strand enteroviral RNA therefore occurs only at sites of active viral replication but not in tissues with mere persistence of the viral genome.

METHODS AND RESULTS

We investigated enteroviral RNA replication versus enteroviral RNA persistence in endomyocardial biopsies of 45 patients with left ventricular dysfunction and clinically suspected myocarditis. Using reverse-transcriptase polymerase chain reaction in conjunction with Southern blot hybridization, we established a highly sensitive assay to specifically detect plus-strand versus minus-strand enteroviral RNA in the biopsies. Plus-strand enteroviral RNA was detected in endomyocardial biopsies of 18 (40%) of 45 patients, whereas minus-strand RNA as an indication of active enteroviral RNA replication was detected in only 10 (56%) of these 18 plus-strand-positive patients. Enteroviral RNA was not found in biopsies of the control group (n=26).

CONCLUSIONS

These data demonstrate that a significant fraction of patients with left ventricular dysfunction and clinically suspected myocarditis had active enteroviral RNA replication in their myocardium (22%). Differentiation between patients with active viral replication and latent viral persistence should be particularly important in future studies evaluating different therapeutic strategies. In addition, molecular genetic detection of enteroviral genome and differentiation between replicating versus persistent viruses is possible in a single endomyocardial biopsy.

[Syncope in 3rd degree atrioventricular block. Detection of virus genome in the myocardium]

HISTORY AND CLINICAL FINDINGS

A 28-year-old woman was admitted after syncope which had been preceded by several flulike episodes. There was no history of any other serious disease. Physical examination was unremarkable. Heart sounds were regular and normal, there were no murmurs.

INVESTIGATIONS

White cell count was 9400/microliter, with a normal differential count. Erythrocyte sedimentation rate and C-reactive protein were also normal. Virus serology revealed no abnormality. The electrocardiogram (ECG) showed complete (third degree) atrioventricular (AV) block with an idioventricular rhythm of 38 beats/min and right bundle branch block pattern.

TREATMENT AND COURSE

A temporary transvenous pacemaker was inserted on the first hospital day. As myocarditis was suspected a right ventricular endomyocardial biopsy was obtained. Histological and immunohistological examinations demonstrated no unequivocal findings. But molecular-biological tests revealed. Coxsackie-B3 virus genome. The pacemaker was removed on the 6th day, when the ECG had shown intermittent second degree AV block. Regular sinus rhythm with a PR interval of 0.18 s was recorded on day 12, and 24-hour ECG monitoring for several days until her discharge on the 18th day confirmed this rhythm throughout.

CONCLUSION

In aetiologically undetermined disease molecular-biological techniques can be indispensable for the exact diagnosis and may be decisive for administering specific treatment.

[Detection of enteroviral RNA in endomyocardial biopsies in inflammatory cardiomyopathy and idiopathic dilated cardiomyopathy]

The role of enteroviral myocardial infection in the development of dilated cardiomyopathy could only be substantiated after the introduction of molecular biological techniques (polymerase chain reaction, in-situ hybridization) in virological diagnostics of dilated cardiomyopathy. By using histological and especially immunohistological techniques for the detection of myocardial inflammation in patients with the tentative clinical diagnosis of dilated cardiomyopathy, a differentiation between inflammatory cardiomyopathy and idiopathic dilated cardiomyopathy on the basis of the WHO classification 1995 (31) was made. Inflammatory cardiomyopathy is defined by myocarditis in association with cardiac dysfunction and is diagnosed by established histological and especially immunohistological techniques. The combination of histological, immunohistological, and molecularbiological techniques enabled a subgroup analysis of the incidence of enteroviral myocardial RNA in patients with inflammatory cardiomyopathy in comparison to patients with idiopathic dilated cardiomyopathy. The study involved a total of 75 patients with impaired left ventricular function (EF < 50%) and the tentative clinical diagnosis of dilated cardiomyopathy. Right ventricular endomyocardial biopsies were obtained from all patients for further clarification of the cause of left ventricular functional disorder. All biopsies were analyzed for the presence of acute and chronic inflammatory myocardial alterations by histological ("Dallas" criteria) and immunohistological techniques (lymphocytic infiltrates, MHC antigen expression). Furthermore, each biopsy was examined by reverse transcriptase polymerase chain reaction (RT-PCR) in combination with Southern blot hybridization for the presence of enteroviral RNA. Active myocarditis was excluded in all patients by histological examination according to the "Dallas" criteria. Using immunohistological techniques, 26/75 patients (35%) had evidence for chronic inflammatory myocardial alterations in the sense of lymphocytic infiltrates (> or = 2,0 CD3 T-lymphocytes/ visual field at 400 magnification (HPF); > or = 7 CD3 T-lymphocytes/mm2). These patients were diagnosed as having inflammatory cardiomyopathy. To differentiate between patients with and without myocardial inflammation, cases with focal cellular infiltration and an average cell number between 2.5 and 2.0 CD3 T-lymphocytes/HPF and an increased expression of additional immune markers, i.e., MHC antigens, were not addressed in the group of patients with inflammatory cardiomyopathy. This is in contrast to Kühl et al (19). Consequently these patients were classified as patients with idiopathic dilated cardiomyopathy. These criteria of diagnosing myocardial inflammation were based on published results (20, 23, 26, 27, 49) and on our own control group (n = 85) (19) in which mean CD3 T-lymphocyte count/HPF in normal myocardial tissue were 0.7 (range 0.0-1.4). In addition, a subgroup analysis was performed of patients with a CD3 T-lymphocyte count > or = 3 CD3 T-lymphocytes/HPF (> or + 11 CD3 T-lymphocytes/mm2). The other 49/75 patients without myocardial inflammation (< 2.0 CD3 T-lymphocytes /HPF) were diagnosed as having idiopathic dilated cardiomyopathy. In 27/75 patients (36%), RT-PCR in combination with Southern blot hybridization revealed enteroviral RNA in the endomyocardial biopsies. The detection rate of enteroviral RNA did not differ between inflammatory cardiomyopathy (8/26 (31%)) and idiopathic dilated cardiomyopathy (19/49 39%)). In the subgroups of patients with a CD3 T-lymphocyte cell count > or = 3 CD3 T-lymphocytes/HPF (> or = 11 CD3 T-lymphocytes/mm2) (mean 4.4 +/-2.1 CD3 T-lymphocytes/HPF), three of the ten patients were enteroviral RNA positive (30%). In summary, the introduction of histological and immunohistological techniques in the extended diagnostics of dilated cardiomyopathy enables a subgroup analysis of the incidence of enteroviral myocardial RNA in

[Cardiac sarcoidosis: diagnostic validation by endomyocardial biopsy and therapy with corticosteroids]

A 66-year-old woman with pulmonary sarcoidosis had a 1.5-year history of congestive heart failure presenting as dilated cardiomyopathy. Transvenous endomyocardial biopsy specimens initially revealed lymphocytic myocarditis but subsequently showed a non-cesating giant-cell granuloma typical of Boeck's sarcoid. In addition to standard therapy the patient was given corticosteroids. This case illustrates the difficulties and importance of diagnosing cardiac sarcoidosis as a potentially treatable form of dilated cardiomyopathy.

The role of sensitized T-cells in myocarditis and dilated cardiomyopathy

Enteroviruses like coxsackie are known to cause myocarditis both in animals and humans and enteroviral genom was found in endomyocardial biopsies of patients with myocarditis and dilated cardiomyopathy. However, subsequent to the initial viral infection, immune mechanisms seem to play an important role in the pathogenesis of both diseases. Using synthetic peptides, it was possible to identify T-cell epitopes of coxsackie B3 virus and to test their significance in the pathogenesis of myocarditis in the animal model. The T-cell response against coxsackie virus and autoantigens like the adenine nucleotide translocator is also present in the human disease, since sensitized T-cells can be cultured from about 50% of endomyocardial biopsies of patients with myocarditis and dilated cardiomyopathy. The significance of the cellular immune responses in the human disease can be demonstrated by the transfer of peripheral blood leukocytes of patients with chronic myocarditis into severe combined immune deficiency mice that develop human cellular infiltrates of the myocardium and an impairment of the left ventricular function within 60 days. Thus, these results show the presence and importance of cellular immune responses in the pathogenesis of myocarditis and dilated cardiomyopathy.

Impairment of left ventricular function in combined immune deficiency mice after transfer of peripheral blood leukocytes from patients with myocarditis

Autoimmune mechanisms are suspected to play an important role in the pathogenesis of human myocarditis. In order to evaluate the significance of autoimmune leukocytes for the development of human myocarditis (MC) and subsequent heart failure, we transferred 15 x 10(6) or 50 x 10(6) peripheral blood leukocytes (PBLs) from patients with immunohistologically proven MC and impaired left ventricular function into severe combined immune deficiency (SCID) mice that possess neither B nor T lymphocytes. PBLs from seven patients and five healthy controls were transferred into three SCID mice each by intraperitoneal injection. After 60 days human PBLs could be demonstrated in the peripheral blood of SCID mice, representing up to 10% of peripheral blood mononuclear cells. Likewise, human immunoglobulins were present in all transfused SCID mice (up to 3 mg.ml-1 IgG and IgM); however, autoantibodies against the adenine nucleotide translocator, a myocardial autoantigen, were only present in the mice receiving PBLs from patients with MC. Infiltrating human lymphocytes were also only found in the hearts of SCID mice having received PBLs from MC patients, but not in those receiving PBLs from normal controls. When we measured the slope of the left ventricular pressure pulse by direct puncture under ether anaesthesia, we found it to be decreased (dp/dt = 1750 +/- 194 mmHg.s-1 in mice receiving PBLs from MC patients, compared with mice receiving PBLs from controls (dp/dt = 2456 +/- 92 mmHg.s-1 or receiving no transfusion (dp/dt = 2576 +/- 142 mmHg.s-1. These results demonstrate that the impairment of the ventricular function seen in patients with MC can be transferred to SCID mice by transfer of PBLs. This proves the significance of autoimmune mechanisms for the pathogenesis of MC.

Transfer of human myocarditis into severe combined immunodeficiency mice

Severe combined immunodeficiency (SCID) mice possess neither T nor B lymphocytes and are thus suitable recipients for lymphocytes of different species. Because autoimmune mechanisms are suspected in the pathogenesis of myocarditis (MC), we attempted to determine whether peripheral blood lymphocytes (PBLs) from patients with MC could be transferred into SCID mice and whether they had an autoimmunologic effect. Groups of three mice each were injected intraperitoneally with up to 50 million PBLs from five MC patients with autoantibodies against the adenine nucleotide translocator (ANT), a myocardial autoantigen. The PBLs from three healthy blood donors were used as controls. After 60 days, human PBLs could be demonstrated in the peripheral blood of the SCID mice transfused with the PBLs of MC patients, representing up to 9.9% of the peripheral blood mononuclear cells. The transfused SCID mice sera showed human immunoglobulin levels of up to 3 mg/mL, both IgG and IgM. Autoantibodies against ANT were present in the mice receiving PBLs from MC patients but not from the control subjects. In addition, infiltrating human lymphocytes were present in the hearts of the SCID mice transfused with PBLs from MC patients. The presence of an ongoing autoimmune process in the SCID mice transfused with PBLs from MC patients is suggested by increased levels of soluble interleukin-2 receptor in the serum in contrast to SCID mice transfused with PBLs from healthy blood donors. We conclude that the autoimmune reactions seen in human MC can be transferred to SCID mice by the transfer of PBLs from MC patients. These findings stress the significance of autoimmune mechanisms in the pathogenesis of human MC.

Identification of serotype-specific and nonserotype-specific B-cell epitopes of coxsackie B virus using synthetic peptides

Coxsackie B viruses are thought to be involved in the induction of myocarditis. However, the diagnosis of acute infections by serology even today is practically impossible. The major problem is that no antigenic determinants of coxsackie B viruses have been identified or characterized which could be used as antigens in a rapid routine antibody screening test. Therefore, we synthesized overlapping peptides according to the sequence of the capsid protein VP1 of coxsackie B3 (CB3) virus in order to identify antigenic determinants located on VP1. Using sera raised against CB3 in mice, we were able to identify several antigenic determinants of CB3. Here we present a characterization of three epitopes found. We also tested the type-specificity of these antigenic determinants by using rabbit antisera against coxsackie viruses B1-B6. One antigenic determinant, peptide VP1-1, representing residues 1-15 of VP1, reacted highly type-specific for CB3. A second antigenic determinant (peptide VP1-3, residues 21-35 of VP1) reacted as well with the anti-CB3 sera as with the anti-CB4 sera. Therefore, the peptide VP1-3 seems to represent a non-type-specific antigenic determinant of coxsackie B viruses. Peptide VP1-24 (residues 229-243 of VP1) showed broad cross-reaction with anti-CB sera except with the anti-CB1 sera. This identification of type-specific and non-type-specific epitopes of coxsackie B viruses may provide the basis for the establishment of an effective and fast antibody screening test for coxsackie B viruses in patients with clinically suspected myocarditis.

The possible value of synthetic peptides in the diagnosis and therapy of myocarditis and dilated cardiomyopathy

The adenine nucleotide translocator (ANT) and myosin have been shown to be major autoantigens in myocarditis and dilated cardiomyopathy. We studied the use of synthetic peptides, with sequences derived from ANT and myosin, as antigens in screening tests for autoantibodies in myocarditis (MC) and dilated cardiomyopathy (DCM) and as absorbents for specific elimination of autoantibodies from the sera of patients. Using computer prediction of the secondary structure of the ANT and myosin we identified two sequences of the ANT and three sequences of myosin as possible main antigenic determinants. Using overlapping synthetic peptides and antibodies against them, the antigenicity of the selected determinants was shown. Of 72 sera from patients with MC or DCM 45 (62.5%) bound to the peptides derived from ANT, 32 (44.4%) reacted with the sequences from myosin, in contrast to healthy controls. Using the peptides from the ANT or myosin immobilized on thiopropyl-sepharose, more than 95% of the autoantibodies could be removed specifically from the positive sera. The results demonstrate the usefulness of synthetic peptides as antigens in antibody screening tests in MC and DCM and offers a new approach to the therapy of inflammatory heart disease by specific elimination of autoantibodies.

Cytotoxic T lymphocytes do not control lymphocytic choriomeningitis virus infection of BB diabetes-prone rats

BioBreeding Worcester diabetes-prone (BBdp) rats develop insulin-dependent autoimmune-driven diabetes mellitus spontaneously and intravenous administration of 1 x 10(7) p.f.u. of lymphocytic choriomeningitis virus (LCMV) to young adult mice prevents disease. The virus is lymphotropic, binding to and replicating in such cells. BBdp rats fail to generate virus-specific major histocompatibility complex-restricted cytotoxic T lymphocyte (CTL) responses when challenged with this dose or other doses of LCMV, Pichinde virus or vaccinia virus. Yet such rats clear virus effectively and show no evidence of persistent infection. Associated with this clearance of virus and establishment of immunity is the production of neutralizing antibodies. In contrast, diabetes-resistant (BBdr) rats generate virus-specific CTL responses. Furthermore LCMV binds to fewer lymphoid cells of BBdr rats (in comparison to those of BBdp rats) and replicates in fewer lymphocytes (by one order of magnitude) from these rats. Thus, unlike mice in which CTLs play a dominant role in the control of LCMV infection, BBdp rats do not overcome this infection via CTLs. In addition, both the BBdp rats and their BBdr counterpart may provide useful models for determining whether or how individual lymphocyte subsets function in the induction of CTL responses, for the analysis of virus-induced immunosuppression and for the use of viruses or their products as therapeutic modalities.

Molecular mimicry and myasthenia gravis. An autoantigenic site of the acetylcholine receptor alpha-subunit that has biologic activity and reacts immunochemically with herpes simplex virus

The large majority of patients with the autoimmune disease myasthenia gravis characteristically have detectable antibodies against the acetylcholine receptor (AChR). We used synthetic peptides to identify antibodies in sera of myasthenia gravis patients reactive with the human acetylcholine receptor (HuAChR) alpha-subunit, residues 160-167. Affinity purification of these antibodies, using the HuAChR alpha-subunit 157-170 peptide immobilized on thiopropyl-Sepharose, yielded IgG antibodies that bound to the native AChR and inhibited the binding of alpha-bungarotoxin to the receptor. The HuAChR alpha-subunit 160-167 peptide demonstrated specific immunological cross-reactivity with a shared homologous domain on herpes simplex virus glycoprotein D, residues 286-293, by both binding and inhibition studies. Thus, HuAChR alpha-subunit, residues 160-167, elicits antibodies in myasthenic patients that binds to the native AChR protein and is capable of eliciting a biologic effect. Immunologic cross-reactivity of this "self" epitope with herpes simplex virus suggest that this virus may be associated with the initiation of some cases of myasthenia.

Cross-reactive epitope with Klebsiella pneumoniae nitrogenase in articular tissue of HLA-B27+ patients with ankylosing spondylitis

Synovial tissues from patients with ankylosing spondylitis or reactive arthritis were examined by an immunoperoxidase technique, using antisera to synthetic peptides representing antigens shared between HLA-B27.1 and Klebsiella pneumoniae nitrogenase. With either antiserum, all HLA-B27+ patients with synovial inflammation showed strong immunoperoxidase staining in synovial lining cells, vascular endothelium, and infiltrating inflammatory cells. These findings indicate that antigens showing cross-reactivity between HLA-B27.1 and Klebsiella nitrogenase epitopes are strongly expressed within inflamed synovial tissues of HLA-B27+ patients.

Molecular mimicry between human leukocyte antigen B27 and Klebsiella. Consequences for spondyloarthropathies

Ankylosing spondylitis and Reiter's syndrome are the two major spondyloarthropathies highly associated with human leukocyte antigen (HLA) B27. Although the development of spondylitis is unclear, it has been hypothesized that HLA-B27 may predispose to spondyloarthropathies via the phenomenon of molecular mimicry. A computer search for homologies between HLA-B27 and microbes revealed a sequence of six consecutive amino acids (glutamine-threonine-aspartic acid-arginine-glutamic acid-aspartic acid) shared by HLA-B27.1 (residues 72 to 77), and Klebsiella pneumoniae nitrogenase (residues 188 to 193). Antibodies raised against a peptide derived from HLA-B27 containing this six-amino-acid sequence cross-reacted with the peptide derived from Klebsiella that contained these six amino acids, and vice-versa. These antibodies also reacted with articular tissues from HLA-B27-positive patients with ankylosing spondylitis. Sera from 53 percent of Reiter's patients and 27 percent of patients with ankylosing spondylitis showed binding to these same peptides. These results suggest that molecular mimicry may have a role in disease development.

Abrogation of diabetes in BB rats by acute virus infection. Association of viral-lymphocyte interactions

The BB rat spontaneously develops an insulin-dependent diabetes mellitus (IDDM) that closely resembles this disease in man. The pathogenesis involves autoimmune destruction of pancreatic beta-cells. In the present study, inoculation of diabetes-prone BB rats at 30 days of age with a lymphotropic variant of lymphocytic choriomeningitis virus significantly reduced the incidence of diabetes. Such virus-inoculated, diabetes-free rats had normal levels of pancreatic insulin and little or no mononuclear cell infiltration in the islets. Virus was recovered from lymphocytes by cocultivation with permissive cells. In contrast, virus was not detected in a wide variety of organs, indicating that infection in BB rats was primarily lymphotropic. PBL analyzed by FACS and monoclonal markers showed a marked reduction of pan-T. Th, and T suppressor/cytotoxic lymphocyte subsets restricted to 4 and 7 days after infection when compared with numbers of lymphocytes in uninoculated diabetes-prone rats. To prevent IDDM, replicating virus was required, because the expected incidence of IDDM in diabetes prone rats inoculated with UV-inactivated virus was equivalent to that of untreated animals. These results suggest that a virus can suppress the autoimmune response that would otherwise have caused IDDM and may be useful as a probe in dissecting the molecular basis of this autoimmune disorder.

Abrogation of diabetes in BB rats by acute virus infection. Association of viral-lymphocyte interactions

The BB rat spontaneously develops an insulin-dependent diabetes mellitus (IDDM) that closely resembles this disease in man. The pathogenesis involves autoimmune destruction of pancreatic beta-cells. In the present study, inoculation of diabetes-prone BB rats at 30 days of age with a lymphotropic variant of lymphocytic choriomeningitis virus significantly reduced the incidence of diabetes. Such virus-inoculated, diabetes-free rats had normal levels of pancreatic insulin and little or no mononuclear cell infiltration in the islets. Virus was recovered from lymphocytes by cocultivation with permissive cells. In contrast, virus was not detected in a wide variety of organs, indicating that infection in BB rats was primarily lymphotropic. PBL analyzed by FACS and monoclonal markers showed a marked reduction of pan-T. Th, and T suppressor/cytotoxic lymphocyte subsets restricted to 4 and 7 days after infection when compared with numbers of lymphocytes in uninoculated diabetes-prone rats. To prevent IDDM, replicating virus was required, because the expected incidence of IDDM in diabetes prone rats inoculated with UV-inactivated virus was equivalent to that of untreated animals. These results suggest that a virus can suppress the autoimmune response that would otherwise have caused IDDM and may be useful as a probe in dissecting the molecular basis of this autoimmune disorder.

Antibody to synthetic somatostatin-28(1-12): immunoreactivity with somatostatin in brain is dependent on orientation of immunizing peptide

Rabbits were immunized with synthetic peptides representing the neurotransmitter dodecapeptide somatostatin-28(1-12) (SANSNPAMAPRE) coupled to the carrier protein keyhole limpet hemocyanin (KLH) at either the amino or the carboxyl terminus. Although all rabbits produced high-titer antisera to immunizing peptide, as assayed by ELISA, only rabbits immunized with peptide coupled to carrier at the amino terminus yielded antibodies that bound to native somatostatin in mouse brain slices. This effect of peptide coupling orientation on epitope specificity of peptide antisera is likely to be significant to other investigators who use predetermined peptide sequences to generate immunohistochemical reagents.

Inhibition of diabetes in BB rats by virus infection

BB rats serve as a model for human insulin-dependent diabetes mellitus (IDDM), since without insulin treatment, most 60-140-d-old animals die within 1 to 2 wk of developing polyuria, polydypsia, hyperglycemia, and hypoinsulinemia. Lymphoid cells accumulate in the islets of Langerhans and beta cells undergo destruction. We report that inoculation of such BB rats with lymphocytic choriomeningitis virus (Armstrong strain, clone 13) reduces over a prolonged period the incidence of IDDM, normalizes the concentration of blood sugar and pancreatic insulin, prevents the mononuclear cell infiltration in the islets of Langerhans, and for a short time after inoculation alters T lymphocyte subsets. Thus, a virus might be programmed to carry out useful functions.

Diagnosis of AIDS by using a 12-amino acid peptide representing an immunodominant epitope of the human immunodeficiency virus

We mapped an immunodominant domain of the human immunodeficiency virus (HIV). We selected hydrophilic amino acid sequences encoded by conserved regions of the gag, pol, and env genes of HIV as potential antigenic domains. Eighteen peptides representing these sequences were synthesized; the peptides elicited strong antibody responses in rabbits. Sera from 53 HIV-infected patients and 50 controls were tested against the synthetic peptides. Although no antibodies to peptides from gag, pol, or env gp120 proteins were present, antibodies to four of the six peptides from env gp41 were detected. Epitope mapping using overlapping peptides showed that sera from 53 (100%) of 53 HIV-infected patients (and from none of 50 controls) reacted with peptides aa584-609 and aa598-609 from gp41, sera from 32 (60%) of 53 patients reacted with peptide aa603-614, and sera from 19 (35%) of 53 patients reacted with peptides aa609-620. Thus, amino acid sequence LeuGlyIleTrpGlyCysSerGlyLysLeuIleCys (aa598-609) from the transmembrane glycoprotein is an immunodominant domain of HIV recognized by serum antibodies from HIV-infected patients.

Autoantibodies to HLA B27 in the sera of HLA B27 patients with ankylosing spondylitis and Reiter's syndrome. Molecular mimicry with Klebsiella pneumoniae as potential mechanism of autoimmune disease

Ankylosing spondylitis (AS) and Reiter's syndrome (RS) both show a strong correlation with the HLA B27 haplotype. We studied whether sharing of homologous amino acid sequences in the HLA B27 antigen with an invading microbe might occur, and if so, what is the biological significance of such homology. In a computer search of the Dayhoff data bank, we found a homology of six consecutive amino acids between HLA B27.1 antigen residues 72-77 and Klebsiella pneumoniae nitrogenase residues 188-193. These shared sequences are hydrophilic, suggesting locations on molecules exposed to the cell surface. Immunochemical analysis showed that 18 of 34 sera from patients with RS (53%) and 7 of 24 sera from patients with AS (29%) contained antibodies that bound to a synthesized peptide sequence representing residues 69-84 of HLA B27.1. In contrast, only 1 of 22 sera from healthy, B27+ controls (5%) contained antibodies to this peptide (p less than 0.01). Sera from three HLA B27- patients with RS did not possess antibodies to the HLA B27 peptide. Additionally, greater than 40% of HLA B27 patients with AS or RS had antibodies to Klebsiella residues 184-193, while none of the normal nonarthritic HLA B27 haplotype subjects did. Our results suggest that an autoimmune response(s) directed against HLA B27.1 may be a pathogenic mechanism in a subset of patients with AS and RS. Further, this response may initially be induced against Klebsiella pneumoniae, a microorganism that shares sequence homology with HLA B27.