Two SNPs in the promoter region of the CTLA-4 gene affect binding of transcription factors and are associated with human myasthenia gravis.

OBJECTIVES: The molecular mechanisms underlying the regulation of the CD152 (CTLA-4) gene are largely unknown. Two single nucleotide polymorphisms (SNPs) located in the promoter region are suspected to contribute to the pathogenesis of myasthenia gravis (MG) through regulation of gene expression. SETTING, SUBJECTS AND DESIGN: One hundred and sixty-five unrelated Swedish-Caucasian patients with MG (103 females and 62 males, age 17 to 92 years) and 148 ethnically matched healthy individuals were studied. Gene typing of two SNPs (T/C(-1772) and A/G(-1661)) and quantification of soluble CD152 were performed in the patients. Besides the association studies, the function of these two SNPs is characterized. RESULTS: We present new genetic associations of two SNPs in the CD152 gene with human MG. These SNPs located in the promoter region are involved in transcriptional binding activity for Nuclear Factor I (NF-1) and c/EBPbeta, as demonstrated using chromatin immunoprecipitation and electromobility shift assay. MG patients with the T/C(-1772) polymorphism have elevated levels of sCD152 in sera. CONCLUSIONS: The two SNPs in the promoter region are associated with MG and might cause abnormal alternative splicing and affect the expression of CD152, thereby contributing to the pathogenesis of MG.

Treatment of a patient with myasthenia gravis using antibodies against CD25.

OBJECTIVES: To measure clinical and immunological parameters in a patient with myasthenia gravis (MG) treated with antibodies against CD25 (basiliximab, Simulect). Patient and methods - Injections of basiliximab were given repeatedly together with cyclosporin A and corticosteroids for 9 months to a patient with severe MG. Her muscle function score was monitored and the immunological parameters were followed using ELISA, flow cytometry and radioimmunoassay. RESULTS: The patient improved moderately and corticosteroid treatment could be withdrawn. The percentage of activated CD4+ T cells decreased during treatment, while that of 'naïve' T cells increased. The serum levels of sCD28, sCD152, sCD80, sCD86 and IL-10 decreased. The treatment was stopped due to repeated infections. CONCLUSION: Treatment with basiliximab appears to be suitable only for severely ill patients who do not respond to conventional treatments. However, careful monitoring of side effects is necessary.

Human Soluble CD80 is generated by alternative splicing, and recombinant soluble CD80 binds to CD28 and CD152 influencing T-cell activation.

CD80 is a costimulatory factor mainly expressed on the surface of activated monocytes, B cells and dendritic cells. In this study, we demonstrate that 24% of healthy individuals have soluble forms of CD80, sCD80, in their serum. The concentration of sCD80 ranged from 0 to 1 mg/l. At the mRNA level, we detected a spliced form s1CD80 (771 bp), in unstimulated monocytes and B cells, while another form named s2CD80 (489 bp) was expressed in activated T cells as well as in freshly isolated and activated monocytes. s1CD80 lacks the transmembrane domain, and the IgC-like domain plus the transmembrane domain are spliced out of s2CD80. We also present data demonstrating that recombinant s1CD80 binds to recombinant CD152-Ig and CD28-Ig. It can also bind to T cells, preferentially to activated T cells. Recombinant sCD80 had immunomodulatory effects shown by its inhibition of the mixed lymphocyte reaction and inhibition of T-cell proliferation. sCD80 in human serum adds a new member to the family of soluble receptors, implying a network of soluble costimulatory factors with functional relevance. The inhibitory effect of the recombinant protein on T-cell activation makes it a possible candidate for treatment of diseases associated with hyperactivated T cells.

The soluble forms of CD28, CD86 and CTLA-4 constitute possible immunological markers in patients with abdominal aortic aneurysm.

OBJECTIVE: The T cell co-stimulatory factors CD28 and CTLA-4 and their ligands CD80 and CD86 occur as receptors on T cells and antigen-presenting cells and also in soluble forms in the circulation. We determined the levels of soluble co-stimulatory molecules in patients with abdominal aortic aneurysm (AAA) and normal individuals. We further correlated these soluble co-stimulatory molecules to other clinical parameters of importance such as age of the patient, presence of hypertension, size of the aneurysm and levels of matrix metalloproteinases-9 and C-reactive protein. DESIGN, SETTING, SUBJECTS: This case-control study was designed to quantify the circulating levels of soluble co-stimulatory molecules by an in-house enzyme linked immunosorbent assay. A total of 314 subjects participated in the study including 100 patients and 214 normal controls. The statistical analysis was performed by Mann-Whitney test and Spearman's correlation rank test. RESULTS: Our results show increased plasma levels of sCD28, sCD86 (P = 0.0001) and decreased plasma levels of sCTLA-4 (P = 0.0018) in the patients compared with normal individuals. The levels of these factors were not related to the age of the patient, size of aneurysm or levels of C-reactive protein in plasma. There was, however, a significant inverse relationship between the concentrations of sCTLA-4 and sCD80 with matrix metalloproteinase-9. CONCLUSIONS: We suggest that soluble co-stimulatory molecules serve as biomarkers for the estimation of immune activation in AAA patients.

A clinical and immunological study of a myasthenia gravis patient treated with infliximab.

OBJECTIVES: To measure clinical and immunological parameters in a patient with myasthenia gravis (MG) treated with antibodies against tumour necrosis factor-alpha (infliximab, Remicade). PATIENT AND METHODS: A patient with severe MG received repeated injections of infliximab. His muscle function score was monitored and the immunological parameters were followed using enzyme-linked immunosorbent assay, flow cytometry and radioimmunoassay. RESULTS: The patient improved in muscle fatigability tests and the levels of antibodies against the acetylcholine receptor decreased during treatment. The activation marker human leucocyte antigen-DR on CD4(+) T cells also decreased. CONCLUSION: Treatment with infliximab might be beneficial for patients with severe MG but demands careful monitoring of possible serious side-effects.

Raised prolactin levels in myasthenia gravis: two case reports and a study of two patient populations.

OBJECTIVES: To describe two patients with myasthenia gravis (MG) and prolactinoma and analyze the associations between MG and prolactin (PRL) levels. DESIGN: Two case reports and a case-control study of PRL levels in 192 patients with MG. PARTICIPANTS: The Immunological Research Laboratory, Center for Molecular Medicine, Department of Medicine and the Department of Neurology, Karolinska Institutet, Stockholm, Sweden; St Petersburg Medical Academy for Postgraduate Studies, and St Petersburg State Medical Pediatric Academy, Russia. RESULTS: Two women with MG and thymic hyperplasia accompanied by prolactinomas are described. The levels of plasma PRL were raised in 101 women with MG, but not in 91 men. There was an association between high PRL levels and high levels of autoantibodies against the acetylcholine receptor. CONCLUSIONS: There is an association of MG with raised levels of PRL in women. PRL has stimulating effects on immune activation and the increased levels might thus be implied in the pathophysiology of MG.

Characterization of the expanded T-cell populations in patients with Wegener's granulomatosis.

OBJECTIVES: Wegener's granulomatosis (WG) is a chronic inflammatory disease characterized by granulomatosis inflammation, systemic vasculitis and glomerulonephritis. In patients, the peripheral T cells are characterized by mono/oligoclonal CD4+/CD8+ T-cell AV/BV receptor expansions, with aberrant expression of activation markers. This study was designed to characterize the phenotypic differences between the expanded and nonexpanded T-cell populations. Expression of markers for activation, costimulation and adhesion molecules was examined. As earlier studies have shown aberrant expression of CD28/CD152, we also analysed the expression of another costimulatory system, the tumour necrotic factor receptor (TNFR) superfamily proteins. DESIGN: Fluorocrome-conjugated monoclonal antibodies and flow cytometry was used to analyse the expression of the different markers on the surface of the expanded and nonexpanded subsets of T cells. SETTING: The Karolinska Hospital and Karolinska Institutet in Stockholm, Sweden. SUBJECTS: Nine patients with WG (six men and three women) had 16 TCRAV/BV CD4+/CD8+ expanded populations that were characterized. RESULTS: The expanded TCRA/BV CD4+ and CD8+ cells had lower percentages of cells expressing CD28 and higher of those expressing CD152 (CTLA-4). The expanded CD4+ population had more cells expressing HLA-DR, CD57 and CCR5 (CD195), whilst the expression of CD25 was present on fewer of the expanded cells. The expanded CD8+ population contained more cells expressing CD137 (4-1BB), CD137 (4-1BBL), CD30 (Ki-1), CD40 and CD134 (OX40). CONCLUSIONS: There were marked differences in the phenotypes of expanded and nonexpanded T-cell populations.

Expression of OX40 (CD134) on CD4+ T-cells from patients with myasthenia gravis.

Myasthenia gravis (MG) is commonly regarded as the prototype of an antibody-mediated, organ-specific autoimmune disease. Antibodies against the acetylcholine receptor (AChR) on the muscle endplate trigger its typical clinical manifestations of weakness and fatiguability. T-B cell interactions are thought to play a crucial role in the pathogenesis of MG. OX40 (CD134), a costimulatory molecule that is expressed on activated CD4+ T-cells, might contribute to the development or pathogenesis of immune-mediated diseases such as rheumatoid arthritis and graft-versus-host disease. In the present study, we investigated the expression of OX40 on CD4+ T-cells from patients with MG and healthy individuals. Results from 36 MG patients and 28 healthy controls revealed that more freshly isolated CD4+ T-cells from MG patients expressed OX40 than cells from healthy individuals. High levels of antibodies against the AChR, thymic hyperplasia and onset at an early age were associated with elevated expression of OX40. Upon activation by various concentrations of anti-CD3 antibodies, CD4+ T-cells from MG patients showed a tendency toward higher levels of OX40 expression than cells from healthy individuals. Given the role of OX40 in the immune system, we conclude that OX40 might contribute to the development of MG.

beta2 Adrenoceptor gene single nucleotide polymorphisms are associated with rheumatoid arthritis in northern Sweden.

BACKGROUND: beta(2) Adrenoceptor (beta(2)-AR) represents a link between the sympathetic nervous system and the immune system, and may be involved in human rheumatoid arthritis (RA). The gene encoding beta(2)-AR contains three single nucleotide polymorphisms (SNPs) at amino acid positions 16, 27, and 164. OBJECTIVE: To examine the common variants at positions 16 and 27 and their association with RA. METHODS: An allele-specific polymerase chain reaction to determine the common variants at positions 16 and 27 was used in 154 patients with RA and 198 ethnically matched healthy subjects from northern Sweden. RESULTS: Carriage of Arg16 and of Gln27 was associated with RA. Carriage of Gln27 was associated with activity of the disease and in combination with non-carriage of Arg16 with higher levels of rheumatoid factor. CONCLUSION: The beta2-AR SNPs may thus constitute an additional non-major histocompatibility complex association in RA.

Allelic polymorphisms in the repeat and promoter regions of the interleukin-4 gene and malaria severity in Ghanaian children.

Immunoglobulin E has been associated with severe malaria suggesting a regulatory role for interleukin (IL)-4 and/or IgE in the pathogenesis of severe malaria. We have investigated possible associations between polymorphisms in the IL-4 repeat region (intron 3) and promoter regions (IL-4 +33CT and - 590CT) in Ghanaian children with severe malaria. There was a significantly higher frequency of IL-4 intron-3 B1B1 genotype in the cerebral malaria group [P < 0.0001, odds ratio (OR) = 8.7]. The genotype and allele frequencies of the IL-4 -590 and +33 polymorphisms did not differ between the four study groups. Carriers of IL-4 +33T/-590T with cerebral malaria had elevated total IgE compared to non-carriers (P = 0.03). Our data suggest that IL-4 and/or IgE play a regulatory role in the pathogenesis of severe or complicated malaria.

Circulating CD4+CD25+ and CD4+CD25+ T cells in myasthenia gravis and in relation to thymectomy.

Studies in experimental animal models of human autoimmune diseases have revealed that CD4(+)CD25(+) T regulatory (Tr) cells are of thymic origin and have potentials in preventing auto-aggressive immunity. Myasthenia gravis (MG) is the best-characterized autoimmune disease. Changes in the thymus are found in a majority of patients with MG. Thymectomy has beneficial effects on the disease severity and course in a substantial proportion of MG patients. But the occurrence and characteristics of Tr cells have not yet been defined in MG. We determined the frequencies and properties of circulating CD4(+)CD25(+) versus CD4(+)CD25(-) cells in MG patients and healthy controls (HCs), with special focus on the effect of thymectomy on CD4(+)CD25(+) cells. CD4(+)CD25(high) cells comprise only about 2% of blood lymphocytes in both MG patients and HCs. Frequencies of CD4(+)CD25(high) cells were similar in MG patients irrespective of treatment with thymectomy. CD4(+)CD25(+) cells in both MG patients and HCs are mainly memory T cells and are activated to a greater extent than CD4(+)CD25(-) cells, as reflected by high levels of CD45RO and human leucocyte antigen (HLA)-DR-positive cells. In both MG patients and HCs, CD4(+)CD25(+) cells also contained a high proportion of CD95-expressing cells as possible evidence of apoptosis-proneness. Upon stimulation with anti-CD3/CD28 monoclonal antibodies, CD4(+)CD25(+) cells responded more vigorously than CD4(+)CD25(-) cells in MG, irrespective of treatment with thymectomy, as well as in HCs. Although CD4(+)CD25(-) cells are mainly naïve T cells, in non-thymectomized MG patients, they are activated to a greater extent as reflected by higher expression of HLA-DR and CD95 on the surface compared to HCs. The data thus show that there is no deficiency of CD4(+)CD25(+) cells in MG, nor is the proportion of CD4(+)CD25(+) cells influenced by thymectomy.

The autoimmune T and B cell repertoires in monozygotic twins discordant for myasthenia gravis.

Two pairs of monozygotic twins, discordant for myasthenia gravis (MG) for more than 30 years, were studied regarding T cell and antibody reactivity against disease related autoantigens, the acetylcholine receptor, one idiotypic and one anti-idiotypic human monoclonal antibody. The healthy and myasthenic twins had very similar autoantibody repertoires. IgG fractions from both healthy and myasthenic twins had the same capacity to decrease the free acetylcholine receptor content in mice after passive transfer. In comparison with their myasthenic sisters, the healthy twins had lower T cell responses against the acetylcholine receptor.

beta2-adrenergic receptor gene single-nucleotide polymorphisms are associated with rheumatoid arthritis in northern Sweden.

The beta2-adrenergic receptor (beta2-AR) belongs to the group of G-protein-coupled receptors and is present on skeletal and cardiac muscle cells and on lymphocytes. The gene encoding beta2-AR (ADRB2) displays a moderate degree of heterogeneity in the human population and the distributions of single-nucleotide polymorphisms (SNPs) at amino acid positions 16, 27, and 164 are changed in asthma, obesity, and hypertension and in the autoimmune disease myasthenia gravis. An involvement of the beta2-AR has also been suggested in human rheumatoid arthritis (RA) and its animal model. We describe here an increased prevalence of the alleles Arg16 and Gln27 and a lower prevalence of homozygosis for Gly16 and Glu27 in patients with RA. Patients having the genotype combination GlyGly16-GlnGlu27 had higher levels of rheumatoid factor (RF) and a more active disease than other patients. Patients having the genotype Arg16-Gln27+ had higher levels of RF when compared to those having Arg16+Gln27+, and patients who were carriers of Gln27 had a more active disease than non-carriers of Gln27. Our results show an association of beta2-AR SNPs with RA in a population from the northern part of Sweden. Our study also confirms the strong linkage disequilibrium of genotypes at amino acid positions 16 and 27.

Polymorphisms in interleukin-1beta and interleukin-1 receptor antagonist genes and malaria in Ghanaian children.

We have investigated the possible associations between polymorphisms in two interleukin-1 (IL-1) genes and severity of Plasmodium falciparum malaria in Ghanaian children with cerebral malaria, severe anaemia or uncomplicated malaria and controls. There was no significant difference in genotype and allele frequencies in IL-1beta exon 5 or interleukin-1 receptor antagonist (IL-1ra) polymorphisms between the studied groups, suggesting that the two polymorphisms may not be involved in the pathogenesis of severe malaria. When parasitaemias in uncomplicated malaria patients were evaluated, a significantly higher level of parasitaemia was observed among carriers of IL-1beta A2 allele as compared with noncarriers of this allele (P = 0.01). The mean parasitaemia in an age-matched asymptomatic group did not reveal such associations. These data suggest that IL-1beta exon 5 allele 2 may play a possible role in the clinical outcome of uncomplicated malaria.

Increased levels of autoantibodies against copper-oxidized low density lipoprotein, malondialdehyde-modified low density lipoprotein and cardiolipin in patients with rheumatoid arthritis.

OBJECTIVES: To analyse the association of autoantibodies against cardiolipin (CL) and oxidized low density lipoproteins [copper-oxidized low density lipoprotein (oxLDL), malondialdehyde-modified LDL (MDA-LDL)] with rheumatoid arthritis (RA) and cardiovascular complications. METHODS: One hundred and twenty-one patients with RA were consecutively included. Autoantibodies were determined by ELISA. Healthy individuals from the same region were used as controls. RESULTS: Levels of IgG, IgM and IgA antibodies against MDA-LDL and CL, as well as IgG and IgA antibodies against oxLDL were increased in the patients (P<0.01). The prevalence of IgG, IgM and IgA antibodies against CL was higher than in the normal population (74, 82 and 14%, respectively). The prevalence of IgG and IgA antibodies against oxLDL was also significantly increased (35 and 25%, respectively) and so was the prevalence of IgG and IgM antibodies against MDA-LDL (17 and 26%, respectively) compared with controls. The levels of IgM and IgA antibodies against aCL and IgM against MDA-LDL were increased in patients with extra-articular manifestations. Patients who developed myocardial infarction had a higher prevalence of IgG antibodies against MDA-LDL (P=0.04). There were substantial correlations between the levels of antibodies against oxLDL, MDA-LDL and CL. CONCLUSIONS: RA patients had increased levels and prevalence of autoantibodies against CL, oxLDL and MDA-LDL, with associations to severity of disease and cardiovascular complications.

A CTLA-4 gene polymorphism at position -318 in the promoter region affects the expression of protein.

CTLA-4 is an important negative regulator of the immune system. The regulation of the CTLA-4 gene (Ctla-4) transcription is poorly understood. A single nucleotide polymorphism (SNP) at -318 in the Ctla-4 promoter region is associated with certain autoimmune diseases. Since the -318 SNP occurs in a potential regulatory region, it is conceivable that the C' T transition may affect the expression of Ctla-4. In the present study, we show that the -318T allele is associated with a higher promoter activity than the -318C allele (8.13 +/- 0.46 vs 6.87 +/- 0.49). The presence of the -318T allele may thus contribute to up regulation of the expression of CTLA-4, and consequently represent one mechanism to inhibit exaggerated immune activity.

CDS1 and promoter single nucleotide polymorphisms of the CTLA-4 gene in human myasthenia gravis.

The cytotoxic T lymphocyte associated protein 4 (CTLA-4) gene (Ctla-4) is a candidate gene for autoimmune disease. We here report results of two single nucleotide polymorphisms (SNPs) in the Ctla-4, a +49 A/G SNP in CDS1 and a C/T promoter SNP at position -318. There were no differences in these two SNPs between patients and healthy individuals. The frequency of allele G and genotype G/G at position +49 in CDS1 was increased in patients with thymoma when compared with patients with normal and hyperplastic thymic histopathology. Patients with the G/G genotype had signs of immune activation manifested as higher levels of serum IL-1beta and higher percentage of CD28(+) T lymphocytes. There was a strong linkage between the 86bp allele in the 3'-UTR and the A(+49) allele in CDS1. Our results suggest that the SNP at position +49 in CDS1 might be associated with the manifestations of MG.

Expression of CTLA-4 by human monocytes.

Cytotoxic T lymphocyte-associated molecule-4 (CTLA-4) is a receptor present on T cells that plays a critical role in the downregulation of antigen-activated immune responses. CTLA-4 interacts with the ligands CD80 and CD86 on antigen-presenting cells (APC), and also directs the assembly of inhibitory signalling complexes that lead to quiescence or anergy. In this study, we show that human monocytes constitutively express CTLA-4. About 3% of monocytes expressed CTLA-4 on the cell surface, whereas the intracellular expression was higher and present in about 20% of the monocytes. The sequences of the cDNAs from human monocytes were identical to the sequences of CTLA-4 from T cells. Expression of CTLA-4 was also confirmed in the activated myelomonocytic cell lines U937 and THP-1. Monocytes, but not T cells, activated by interferon (IFN)-gamma also secreted soluble CTLA-4 in vitro. The CTLA-4 expression was upregulated upon treatment with phorbol 12-myristate 13-acetate (PMA) and IFN-gamma. This increased expression could be partially abolished by staurosporine, an inhibitor of protein kinase C (PKC). Ligation of CTLA-4 in the monocyte-like cell-line U937 with antibodies against CTLA-4 partially inhibited the proliferation of cells and the upregulation of cell-surface markers CD86, CD54, HLA-DR and HLA-DQ induced by IFN-gamma and Staphylococcus aureus, Cowan I strain (SAC). Ligation of CTLA-4 suppressed the PMA-stimulated activation of transcription activator protein 1 (AP-1) and nuclear factor (NF)-kappaB in the U937 cell line, indicating the involvement of an inhibitory signal transduction. These data provide the first evidence that CTLA-4 is constitutively expressed by monocytes and thus might be important for the regulation of immune mechanisms associated with monocytes.