Decrease of blood anti-α1,3 Galactose Abs levels in multiple sclerosis (MS) and clinically isolated syndrome (CIS) patients

The etiology of multiple sclerosis (MS) remains elusive. Among the possible causes, the increase of anti-Neu5Gc antibodies during EBV primo-infection of Infectious mononucleosis (IMN) may damage the integrity of the blood-brain barrier facilitating the transfer of EBV-infected B cells and anti-EBV T cell clones in the brain. We investigated the change in titers of anti-Neu5Gc and anti-α1,3 Galactose antibodies in 49 IMN, in 76 MS, and 73 clinically isolated syndrome (CIS) patients, as well as age/gender-matched healthy individuals. Anti-Gal and anti-Neu5Gc are significantly increased during IMN (p=0.02 and p<1.10^-4 respectively), but not in acute CMV primo-infection. We show that, whereas there was no change in anti-Neu5Gc in MS/CIS, the two populations exhibit a significant decrease in anti-Gal (combined p=2.7.10^-3), in contrast with patients with non-MS/CIS central nervous system pathologies. Since anti-Gal result from an immunization against α1,3 Gal, lacking in humans but produced in the gut, our data suggest that CIS and MS patients have an altered microbiota or an altered response to this microbiotic epitope.

Characterization of a new human monoclonal antibody directed against the Vel antigen

BACKGROUND AND OBJECTIVES

The Vel blood group antigen is a poorly characterized high-prevalence antigen. Until now, anti-Vel antibodies have been observed in only alloimmunized Vel-negative individuals. In this study, we aimed to establish a human hybridoma cell line secreting the first anti-Vel monoclonal antibody (mAb), clone SpG213Dc.

MATERIALS AND METHODS

Peripheral blood lymphocytes from a French Vel-negative woman with anti-Vel in her plasma were transformed with Epstein-Barr virus and then hybridized with the myeloma cell line Sp2/O-Ag14 using the polyethylene glycol (PEG) method. A specific anti-Vel mAb was successfully produced and was extensively characterized by serological, flow cytometry and Western blot analyses.

RESULTS

One human anti-Vel-secreting clone was produced and the secreted anti-Vel mAb (SpG213Dc) was examined. The specificity of the SpG213Dc mAb was assessed by its reactivity against a panel of nine genotyped RBCs including, respectively, three Vel-negative and six Vel-positive (three wild-type homozygous and three heterozygous) samples using flow cytometry method. Vel-positive RBCs were specifically stained and were subsequently used to perform Western blot and immunoprecipitation analysis of the Vel antigen.

CONCLUSION

Serological characterization of the new monoclonal anti-Vel SpG213Dc showed a heterogeneous level of expression of the Vel antigen on the different RBCs. Our results suggest that the mAb SpG213Dc can be reliably used as a blood grouping reagent, thus allowing the mass-scale phenotyping of blood donors to strengthen rare blood banks with Vel-negative RBC units.

Evaluation of CytoDiff™ on cord blood WBC differential

INTRODUCTION

An umbilical cord blood bank was recently opened in our institution as an alternative source of hematopoietic stem cells. Before inclusion of a cord blood in an international register, a WBC with differential is requested, among others. Currently, the reference method is the microscopic manual count, and we sought to evaluate the routine flow cytometric method (CytoDiff™) as an alternative.

METHODS

A total of 161 cord bloods were analyzed between November 2010 and February 2011. WBC differentials were determined for each sample, by (i) the cell counter (DxH800), (ii) a manual review, and (iii) the flow cytometry using the CytoDiff™ antibody cocktail.

RESULTS

Correlation coefficients between flow cytometry and microscopic count were satisfying for neutrophils, lymphocytes, and immature granulocytes and acceptable for eosinophils. On the other hand, we found lower correlation coefficient for basophils and monocytes. Monocytes' correlation was better when comparing flow cytometry with cell counter.

CONCLUSION

The flow cytometric approach is suitable to realize cord blood WBC differential and allows for the identification of additional cell subsets.

Characterization of intratumoral follicular helper T cells in follicular lymphoma: role in the survival of malignant B cells

Accumulating evidences indicate that the cellular and molecular microenvironment of follicular lymphoma (FL) has a key role in both lymphomagenesis and patient outcome. Malignant FL B cells are found admixed to specific stromal and immune cell subsets, in particular CD4(pos) T cells displaying phenotypic features of follicular helper T cells (T(FH)). The goal of our study was to functionally characterize intratumoral CD4(pos) T cells. We showed that CXCR5(hi)ICOS(hi)CD4(pos) T cells sorted from FL biopsies comprise at least two separate cell populations with distinct genetic and functional features: (i) CD25(pos) follicular regulatory T cells (T(FR)), and (ii) CD25(neg) T(FH) displaying a FL-B cell supportive activity without regulatory functions. Furthermore, despite their strong similarities with tonsil-derived T(FH), purified FL-derived T(FH) displayed a specific gene expression profile including an overexpression of several genes potentially involved directly or indirectly in lymphomagenesis, in particular TNF, LTA, IL4 or CD40LG. Interestingly, we further demonstrated that these two last signals efficiently rescued malignant B cells from spontaneous and rituximab-induced apoptosis. Altogether, our study demonstrates that tumor-infiltrating CD4(pos) T cells are more heterogeneous than previously presumed, and underlines for the first time the crucial role of T(FH) in the complex set of cellular interactions within FL microenvironment.

Soluble human leucocyte antigen-G molecules in peripheral blood haematopoietic stem cell transplantation: a specific role to prevent acute graft-versus-host disease and a link with regulatory T cells

Haematopoietic stem cell transplantation is often complicated by the life-threatening graft-versus-host disease (GVHD) which consists of an allogeneic reaction of the graft cells against the host organs. The aim of this study was to investigate the putative involvement of soluble human leucocyte antigen (sHLA) class I molecules, and particularly sHLA-G molecules, in the occurrence and/or prevention of acute GVHD (aGVHD) in allogeneic peripheral blood stem cell (PSC) transplantation. Whole sHLA class I molecules seem to be involved in aGVHD pathogenesis because detection of a high concentration of these molecules in the first month post allograft is correlated with aGVHD occurrence. Conversely, a high level of sHLA-G molecules before and after allograft could indicate good prognosis in PSC allograft transplantation. sHLA-G molecules seem to be involved in aGVHD prevention, not only because they are enriched in plasma of patients without aGVHD, but also because: (i) a positive correlation has been found between sHLA-G level and CD4+ CD25+ CD152+ natural regulatory T cell (T(reg)) frequency in the blood of transplanted patients; and (ii) the presence of CD4+ CD25+ CD152+ natural T(reg) is correlated with increased sHLA-G expression in in vitro mixed leucocyte reaction cultures. Altogether, these results support the immunomodulatory function of sHLA-G molecules that might create a regulatory network together with the natural T(reg) to foster the induction of a tolerogenic environment and improve PSC transplantation favourable outcome.

A second-generation genomic screen for multiple sclerosis

Multiple sclerosis (MS) is a debilitating neuroimmunological and neurodegenerative disorder. Despite substantial evidence for polygenic inheritance of the disease, the major histocompatibility complex is the only region that clearly and consistently demonstrates linkage and association in MS studies. The goal of this study was to identify additional chromosomal regions that harbor susceptibility genes for MS. With a panel of 390 microsatellite markers genotyped in 245 U.S. and French multiplex families (456 affected relative pairs), this is the largest genomic screen for MS conducted to date. Four regions met both of our primary criteria for further interest (heterogeneity LOD [HLOD] and Z scores >2.0): 1q (HLOD=2.17; Z=3.38), 6p (HLOD=4.21; Z=2.26), 9q (HLOD; Z=2.71), and 16p (HLOD=2.64; Z=2.05). Two additional regions met only the Z score criterion: 3q (Z=2.39) and 5q (Z=2.17). Further examination of the data by country (United States vs. France) identified one additional region demonstrating suggestive linkage in the U.S. subset (18p [HLOD=2.39]) and two additional regions generating suggestive linkage in the French subset (1p [HLOD=2.08] and 22q [HLOD=2.06]). Examination of the data by human leukocyte antigen (HLA)-DR2 stratification identified four additional regions demonstrating suggestive linkage: 2q (HLOD=3.09 in the U.S. DR2- families), 6q (HLOD=3.10 in the French DR2- families), 13q (HLOD=2.32 in all DR2+ families and HLOD=2.17 in the U.S. DR2+ families), and 16q (HLOD=2.32 in all DR2+ families and HLOD=2.13 in the U.S. DR2+ families). These data suggest several regions that warrant further investigation in the search for MS susceptibility genes.

Genetic and functional studies in multiple sclerosis patients from Martinique attest for a specific and direct role of the HLA-DR locus in the syndrome

Among candidate genes involved in multiple sclerosis (MS) genetic susceptibility, MHC genes and particularly HLA-DRB1*1501-DQB1*0602 haplotype play a major role. Based on the strong linkage disequilibrium observed in Caucasians between DRB1*1501 and DQB1*0602 alleles, it is still impossible to draw a firm conclusion about the DRB1 or DQB1 locus involvement. In order to address this issue a strategy associating a genetic and a functional approach was conducted in a population of-non-Caucasian MS patients. We observed that in Martinicans (55 MS and 100 controls), the DRB1*15 and DRB1*07 alleles were positively associated with the disease. However in Martinicans the most common DRB1*15 subtype was *1503 and not *1501. Moreover, in Martinicans, the frequency of DQB1*0602, found in association with other DRB1 alleles than DRB1*15 (42% of DQB1*0602 haplotypes), was not increased in DRB1*15-negative MS patients, suggesting a neutral role of DQB1*0602 in MS genetics. In a second step, we demonstrated the capability of the DRB1*1503 allele associated with MS in Martinicans to present the immunodominant autoantigen MBP 85-99 peptide to a DRB1*1501 restricted MBP specific T cell line. Interestingly, structural features of DRB1*1501 or DRB1*1503 molecules are in good fit with the hypothesis that *1501 and *1503 molecules may act similarly in MS development by presenting the same immunodominant MBP peptide. On the whole, our results show a prominent role of the DRB1 locus (DRB1*1501 and/or DRB1*1503 alleles) in the immunodominant MBP 85-99 peptide presentation to genetically different MS patients and suggest a neutral role of the DQB1 encoded molecule in MS susceptibility.

HLA class I and class II allele and haplotype diversity in Martinicans

The Martinican population is mainly the product of admixture between African people and French Caucasians. The aim of the present study is to investigate at the DNA level the polymorphism of HLA class I (HLA-A, HLA-B) and class II (HLA-DRB1, DQB1 and DPB1) genes in a population of 100 Martinicans. Allelic distributions and interlocus linkage disequilibria were compared to those observed in a French Caucasian population and in African or North American African populations. Our data revealed a higher degree of polymorphism in Martinicans than in Caucasians and showed a prominant contribution of African origin in the admixed genetic feature of this population. African characteristic alleles were significantly represented in Martinicans: A*30, *33 *34, *66, *74, *8001, B*1510, *35, *42, *53, DRB1*0302, *0804, *1202, *1304, *1503, DPB1*0101, *1701, *1801, *3901. Moreover a higher diversity of A*-B* and DRB1*-DQB1* associations was observed in Martinicans compared to Caucasians which also reflects the African genetic background of this population. In the whole, using PCR-based genotyping methods for HLA class I and class II loci, this study allows a preliminary description of HLA allele distribution in this Caribbean island and gives new elements which may be helpful in the anthropologic field as well as in HLA and disease association studies.

Influence of shared epitope-negative HLA-DRB1 alleles on genetic susceptibility to rheumatoid arthritis

OBJECTIVE

Most patients with rheumatoid arthritis (RA) express the shared epitope (SE). It is not known whether SE-negative HLA-DRB1 alleles influence the development of RA. This study examined the influence of SE-negative HLA-DR alleles (DRB1*X) on the development of RA in 3 different French populations.

METHODS

HLA-DRB1 alleles were defined by polymerase chain reaction with sequence-specific oligonucleotide hybridization or sequence-specific primers. SE-negative alleles were classified according to the electric charge of their P4 pocket. HLA-DRB1 alleles *0103, *0402, *07, *08, *11 (except *1107), *12, and *13 have a neutral or negative P4 charge and are called DRB1*XP4n. HLA-DRB1*03, *0403, *0406, *0407, *0901, *1107, *14, *15, and *16 have a positive P4 charge and are called DRB1*XP4p.

RESULTS

Among the SE-negative subjects, DRB1 genotypes with 1 or 2 DRB1*XP4n alleles were significantly overrepresented in the control subjects compared with the RA patients, whereas DRB1*XP4p/XP4p genotypes were equally represented in the patients and controls. In single-dose SE-positive subjects, SE/XP4n genotypes were equally represented in the patients and controls. However, SE/XP4p genotypes were significantly overrepresented in the RA patients.

CONCLUSION

The DRB1*X allele polymorphism influences susceptibility to RA. Alleles that have a neutral or negative electric charge in their P4 pocket (DRB1*XP4n), such as DRB1*0103, *0402, *07, *08, *11 (except *1107), *12, and *13, protect against RA. Alleles that have a positive electric charge in their P4 pocket (DRB1*XP4p), such as DRB1*03, *0403, *0406, *0407, *0901, *1107, *14, *15, and *16, have no influence on the predisposition to RA.

Analysis of TNFalpha microsatellites in 35 patients with primary Sjögren's syndrome

OBJECTIVES

Although the cause of Sjögren's syndrome remains unknown, many arguments suggest a role for both environmental and genetic factors. An association with HLA molecules has been established. Other genes on the short arm of chromosome 6 may be involved, most notably the TNF gene, which may be pivotal in the development of the epithelial lesions.

METHODS

We investigated TNFalpha microsatellites in 35 patients with primary Sjogren's syndrome and in 146 healthy controls.

RESULTS

The frequency of the TNFalpha10 allele showed a non-significant increase in the Sjögren's disease group (28.6% vs 15.8%; P = NS). We found significant increases when we considered only those Sjögren's disease patients with joint manifestations (N = 24; 37.5% vs 15.7%; P < 0.05) or only those with anti-Ro(SSA) antibodies (N = 10; 50% vs 15.7%; P < 0.05).

CONCLUSION

Our data support a role for the TNFalpha10 allele in primary Sjögren's syndrome, particularly those forms with joint symptoms and anti-Ro(SS-A) antibodies.

No evidence for transmission disequilibrium between a new marker at the myelin basic protein locus and multiple sclerosis in French patients

The myelin basic protein (MBP) gene is a candidate locus for susceptibility to multiple sclerosis. Several groups have tested a complex (TGGA)n repeat in the 5' region of this gene for association/linkage with multiple sclerosis, with divergent results. This region of tandem repetitive sequence has been subjected to complex rearrangements, and there is a possibility that alleles of the same size have different internal structures, which reduces the interest of this marker for linkage disequilibrium studies and may at least partly explain the conflicting results obtained so far. To overcome this problem, we isolated a new polymorphic (CA)n repeat within the Golli-MBP locus. The limited number of alleles identified makes this other marker suitable for transmission disequilibrium studies. We tested this marker for linkage with multiple sclerosis, using the transmission-disequilibrium test (TDT) on a sample of 196 nuclear families in which the genotypes of both parents could be unambiguously defined. We found no evidence of transmission disequilibrium between multiple sclerosis and any of the three alleles of this marker, even when the patients were subdivided according to their HLA-DRB1*1501 status. The present data thus provide no evidence for a contribution of the MBP gene to multiple sclerosis susceptibility in French patients.

[Discovery of a chronic HVC infection without seroconversion in a blood donor in France during 28 months]

The HCV-RNA screening technique developed by the French Fractionation and Biotechnology Laboratory singled out in March 1998 a case of positive HCV-RNA viremia in a blood donor without any anti-HCV antibody. That donor was a 46-year-old woman who had made 54 donations of blood products from 1988 to 1997. She had no history of blood transfusion, no history of hepatitis and no life-style risk factor. Clinical examination was normal. Liver tests (serum alanine amino transferases, gamma glutamyl transpeptidase , alkaline phosphatase, bilirubin , prothrombin and albumin) were normal. Total blood count was normal. Lymphocyte count was normal as well as in vitro functional analysis of lymphocytes (stimulation with different antigens). All screening HCV Elisa tests and immunoblot System available on the French market were unable to detect anti-HCV antibodies. Quantification of serum HCV-RNA (Amplicor Monitor Roche) showed 294,000 copies/mL and HCV genotype 1b determination was performed using Innolipa assay. Further examination of the HCV genotype by direct sequencing of the PCR product showed a classical 1b genotype sequence. The hemovigilance inquiry identified 25 labile products distributed since 1988. Analyzing the records of the recipients that have so far been traced and identified revealed three periods: 1997 to 1995: three recipients were found to be positive for anti-HCV antibodies; two are now cured of hepatitis C. In one recipient, direct sequencing after specific PCR of the hypervariable region coding for the envelope domain showed 100% homology with the donor; 1993 to 1990: four recipients were identified and traced without contamination; in 1988: three of four blood product recipients were anti-HCV negative without HCV-RNA viremia. The forth carried anti-HCV antibodies and genotype 1b HCV-RNA but had a history of multiple surgery. Alter et al. [4] and Bush et al. [5] have previously suggested the possibility of a chronic, immunologically silent state of infection. The case described herein, is the first evidence for this hypothesis. Indeed, the donor has not yet seroconverted 28 months after viremia was discovered. This blood donor was identified by HCV-RNA screening of plasma products. The identification of the same sequence in a recipient of blood from this donor clearly establishes the transmission of the virus by transfusion. The prevalence of such cases of infectious silent chronic HCV carriers has to be determined and the mechanisms responsible for the absence of antibody production need to be clarified.

T cell autoreactivity to proinsulin epitopes in diabetic patients and healthy subjects

We investigated the immune response to proinsulin, a potential autoantigen in IDDM secreted exclusively by pancreatic beta-cells. A total of 2,142 short-term cell lines were generated from 19 individuals; seven IDDM patients at the disease onset and 12 control subjects. No increase in the frequency of proinsulin reactive cells was observed in the IDDM group. To define proinsulin epitopes, proliferative responses of proinsulin-specific lines were examined against 10 overlapping 15 amino acid peptides encompassing the human proinsulin sequence. The predominant immune response was directed against the proinsulin p35-50 peptide located in the (C) connecting peptide between the alpha- and beta-chain of insulin. Recognition of the proinsulin p35-50 peptide could be shown by generating specific T cell clones against the peptide. However, unlike responses to other tissue-specific autoantigens there were only low proliferative responses to proinsulin as measured by 3H-thymidine incorporation. This low reactivity may be partially explained by the location of the p35-50 peptide in the C-peptide which is released into the circulation and therefore, may induce a clonal anergy of T reactive cells. However, the significantly higher 3H-thymidine incorporation after CD3-CD28 triggering showed that peptide specific T cells were capable of a significant response with a stronger TCR signal.

Familial factors influence disability in MS multiplex families. French Multiple Sclerosis Genetics Group

BACKGROUND

Both genetic and environmental factors play a role in the pathophysiology of MS and may influence the clinical expression of the disease.

OBJECTIVE

To determine the contribution of familial factors to the clinical expression of MS.

METHODS

The French Multiple Sclerosis Genetics Group identified 87 sibling pairs. For each patient, sex, age at onset, duration of the disease, and disease course from onset were recorded. Disability was determined by the progression index (PI), defined as the ratio of the Expanded Disability Status Scale (EDSS) score disease duration when the latter exceeded 5 years. Statistical analyses were performed either with a group of patients (clinical features, relation between human leukocyte antigen and clinical features) or with a group of sibpairs (concordance for clinical features).

RESULTS

The mean age at onset was 29.6 years, the ratio of women to men was 59:28, and the mean PI was 0.27. There was no correlation for disease course and age at onset between sibs with MS. In contrast, we observed a weak but significant correlation of the PI in MS sibpairs (r = 0.234, p = 0.03).

CONCLUSION

This study revealed a concordance in MS sibling pairs for the disease severity, supporting the hypothesis that the degree of disability might be partly influenced by familial factors (environmental or genetic).

Positive association of the HLA DMB1*0101-0101 genotype with rheumatoid arthritis

OBJECTIVE

HLA DM is a non-classical major histocompatibility complex (MHC) class II molecule that has been shown to facilitate peptide loading with classical class II molecules.

METHODS

In this study, we analysed the polymorphism in exon 3 of HLA DMA and DMB genes by a polymerase chain reaction-sequence-specific oligonucleotide probe method in 163 rheumatoid arthritis (RA) patients and 146 ethnically matched controls. The HLA-DRB1 genotype was also analysed by a reverse-dot blot method.

RESULTS

Our results show in RA patients a significant increase in the HLA DMB*0101 allele frequency (83% vs 72.3% of the controls, P < 1.6 x 10(-3), significance at P < 0.0125) and in the HLA DMB*0101-0101 homozygote genotype frequency [70.8% vs 50% of the controls, P < 4.2 x 10(-4), significance at P < 0.00625, odds ratio (OR) = 2.4, 95% confidence interval (CI): 1.43-4]. The increase in DMB*0101 allele and homozygote genotype frequencies was independent of a linkage disequilibrium between DMB and DRB1 alleles. The analysis of non-random associations between the HLA-DM and DRB1 alleles only revealed a significant association in controls between DMB*0104 and DRB1*07 alleles (delta = 0.01, P < 7 x 10(-4), significance at P < 9.6 x 10(-4)). On the other hand, the DMB*0101-0102 genotype frequency was increased in DRB1*0401-negative RA patients as compared to controls (11% vs 2%, P < 0.011, significance at P < 0.015, OR = 6.2, 95% CI: 1.2-30).

CONCLUSION

Our data suggest that HLA-DM alleles could play a role in the genetic susceptibility to RA.

Pregnancy-associated autoimmune neonatal thrombocytopenia: role of maternal HLA genotype

In a prospective study between 1993 and 1998, data was collected from 46 pregnant women and subsequently from their babies. 25 pregnant women with active autoimmune thrombocytopenic purpura (AITP) or a history of AITP (group A) and 21 pregnant women with isolated thrombocytopenia and identification of specific platelet autoantibodies detected by monoclonal antibody-specific immobilization of platelet antigens (MAIPA) assay (group B) were evaluated for platelet-associated immunoglobulin-G (PAIgG), MAIPA assay and HLA genotype. Neonatal platelet counts were performed at least three times in the first week. 11 neonates were thrombocytopenic (23.9%). No severe haemorrhage occurred. There were no significant differences regarding the values of PAIgG or positive MAIPA tests between mothers of thrombocytopenic or healthy newborns. A significant difference, however, regarding the HLA DRB3* allele was found, with a high incidence in the subgroup of mothers of healthy newborns (P = 0.005). A similar trend was found among mothers with anti-GPIIbIIIa antibodies (P = 0.06). In contrast, HLA DRB5* allele appeared to be present especially in mothers of thrombocytopenic newborns (not significant). Our data suggest that mothers with AITP who have the HLA DRB3* genotype are unlikely to give birth to a thrombocytopenic baby. This study provides a preliminary report on a noninvasive test to identify infants who are likely to be affected.

DRB1*15 and DRB1*03 extended haplotype interaction in primary Sjögren's syndrome genetic susceptibility

OBJECTIVE

Sjögren's syndrome (SS) is a chronic autoimmune disease with a genetic component. Among the genetic factors, the role of HLA class II genes has been suggested and a positive association with DRB1*03 allele has been described. However, there is no consensus on a unique HLA locus for this disease nor on the role of the HLA gene product in the disease. The aim of this study was to analyse prospectively MHC region involvement in the genetic susceptibility to SS by studying DRB1, DQB1, DPB1, TAP1, TAP2 genes and TNF microsatellites in a population of 45 primary SS patients.

METHODS

All the polymorphisms studied were analysed at the genomic level using PCR-based methodologies.

RESULTS

Concerning HLA class II alleles, the highest relative risk to develop the disease was associated with the DRB1*15-DRB1*0301 heterozygous genotype (17.8% vs 3.5% in controls - pc < 0.005, OR = 5.96). Analysing other genes located on the same region allowed us to further determine the DRB1 haplotypes at risk. For instance, the DRB1*0301 haplotype involved in the genetic susceptibility to SS was more often associated with the DPB1* 0201 and TNF-a2 alleles in SS patients than in controls. Moreover, all the DRB1*15-DRB1*0301 SS patients were TAP1-0101, TAP2-0101 homozygous, allowing us to deduce the extended genotype at risk as DRB1*15, TAP1-0101, TAP2-0101/DRB1*0301, TAP1-0101, TAP2-0101 which was carried by only 3 controls out of the 130 tested (p < 0.01, OR = 6.68).

CONCLUSION

This study confirmed the role of the MHC region in the susceptibility to Sjögren's disease, and for the first time suggests a synergistic interaction between two HLA-DRB1 extended haplotypes in the genetic mechanisms controlling the disease.

A systematic study of oligodendrocyte growth factors as candidates for genetic susceptibility to MS. French Multiple Sclerosis Genetics Group

OBJECTIVE

To test 23 genes coding for growth factors and their receptors as candidates for MS genetic susceptibility in 84 multiplex families of French origin by linkage analysis.

BACKGROUND

Epidemiologic studies have indicated that genetic susceptibility in MS exists. To identify MS susceptibility genes, association and linkage studies were performed with candidate genes suggested by the pathology of MS. The most consistent result was genetic association and linkage of MS to human leukocyte antigen (HLA) DR15. Recent advances in the knowledge of MS pathology have suggested that the oligodendrocyte, the myelin-forming cell in the CNS, and its growth factors might play a crucial role in MS.

METHODS

Fifty-two polymorphic markers within or flanking 23 candidate genes were used. Data were analyzed with the maximum likelihood score (MLS) approach. We also searched for a genetic interaction with HLA.

RESULTS

Negative results were obtained for all candidate genes. The lower limits of the relative risk (Xs) possibly excluded for any candidate gene ranged from 1.3 to 2.8. Positive MLS values (up to 0.93) were observed for transforming growth factor beta 3 (TGFbeta3) in HLA DR15-associated families, suggesting a possible role for this growth factor in interaction with HLA.

CONCLUSIONS

Oligodendrocyte growth factors do not play a significant role in MS genetic susceptibility, at least in the tested sample. TGFbeta3, the only gene highlighted by this study, deserves further analysis.

[Polymorphism of the microsatellites and tumor necrosis factor genes in chronic inflammatory bowel diseases]

OBJECTIVES

Multiplex family studies have excluded chromosome 6 as a candidate gene of susceptibility to inflammatory bowel disease. However, one recent study suggested that a gene involved in the pathogenesis of Crohn's disease is located on chromosome 6 confering to a microsatellite allelic combination (a2, b1, c2, d4, e1) a strong genetic risk factor in Crohn's disease. The aim of our study was to determine simultaneously the polymorphisms of the TNF microsatellites and of the genes coding for TNF synthesis in patients with inflammatory bowel disease.

PATIENTS AND METHODS

Sixty patients with ulcerative colitis, 100 patients with Crohn's disease were compared to 64 healthy ethnically matched controls. Five TNF microsatellite loci (a, b, c, d, e) were typed using polymerase chain reaction PCR, and two dimorphisms of TNF alpha and TNF beta (intron 1) were studied by restriction fragment length polymorphism (RFLP).

RESULTS

Allelic frequencies of TNF microsatellites and of TNF alpha and beta genes were similar in Crohn's disease, ulcerative colitis and controls. Five loci microsatellite haplotypes, especially a2 b1 c2 d4 e1 allelic combination, were not more frequent in Crohn's disease (25%) compared to ulcerative colitis (27%) or controls (20%). Subgroups stratification according to clinical characteristics did not modify haplotype frequencies. Analysis of our data taking simultaneously into account the MHC alleles (DRB*01 or DRB1*04) did not modify our data; however, it suggested that extended haplotype on short arm of chromosome 6 differed between patients and controls. Linkage disequilibrium (delta = -360.10(-4); P < 0.01) between a2, b1, c2, d4, e1 allelic combination and DRB1*04 allele was observed only in Crohn's disease.

CONCLUSION

Percentages of patients with Crohn's disease or ulcerative colitis carrying TNF microsatellite or TNF alpha and beta gene haplotypes were similar to those of healthy controls. These data argue against involvement of the TNF locus without exclusion of short arm of chromosome 6 implication in Crohn's disease pathogenesis.

Primary Sjögren's syndrome: role of the HLA-DRB1*0301-*1501 heterozygotes

OBJECTIVE

To examine the respective role of the DRB1*, DQB1*, and DPB1* HLA alleles in primary Sjögren's syndrome (SS) and in the clinical and autoantibody profile of primary SS.

METHODS

HLA-DRB1*, DQB1*, and DPB1* alleles were analyzed in 42 patients with primary SS and 200 controls by reverse dot blot hybridization for DRB1* and DPB1* and by polymerase chain reaction-restriction fragment length polymorphism for DQB1*.

RESULTS

We found a significant increase of the HLA-DRB1*15-*03 heterozygote genotype frequency (19% primary SS vs 3.5% controls; p<0.0006, OR=6.49) and especially for the HLA-DRBI*1501-*0301 genotype (16.7% primary SS vs 3% controls; p<0.002, OR=6.47). The DQB1*0201-*0602 genotype was also significantly increased in primary SS (17.1% primary SS vs 4% controls; p<0.006, OR=4.86). However, the higher risk to primary SS development was associated with the DRB1*1501-*0301 genotype (OR=6.47 vs 4.86). There were no differences between patients and controls in DPB1* allele frequencies. The HLA-DRB1*15-*03 heterozygote genotype was also associated with systemic features such as hematologic manifestations and Raynaud's phenomenon (RP) and with autoantibody production such as antinuclear, anti-Ro(SSA) or La(SSB) autoantibodies and rheumatoid factor.

CONCLUSION

Our data suggest a role of the HLA-DRB1*1501-*0301 heterozygote genotype in susceptibility to primary SS. Moreover, the HLA-DRB1*1501-*0301 genotype was also found to be associated with a particular form of the disease characterized by RP, hematologic manifestations, and autoantibody production.

TCR repertoire and cytokine profiles of cerebrospinal fluid- and peripheral blood-derived T lymphocytes from patients with multiple sclerosis

The cerebrospinal fluid (CSF) represents an important source of T lymphocytes that could be involved in the inflammatory response occurring in the central nervous system in multiple sclerosis (MS). In order to investigate whether the Vbeta gene usage of CSF T lymphocytes is restricted, we analyzed the TCR Vbeta expression in twelve CSF expanded by in vitro culture compared to the paired in vitro-stimulated peripheral blood T lymphocytes. The overexpression of one or two Vbeta genes was demonstrated in ten CSF, but the type of Vbeta over expressed varied from one patient to another. For one patient, the Vbeta repertoire was also investigated by single cell cloning. High frequency of BV6S7-expressing T cell clones was observed in the CSF while no BV6S7 clone was derived from the peripheral blood T lymphocytes suggesting that these cells could be involved in the immunopathological process in the central nervous system (CNS). The cytokine patterns of the T cell clones derived from the CSF- and peripheral blood-T lymphocytes of this patient were determined. The CSF T cell clones produced higher levels of cytokines than the peripheral blood T cell clones. The high frequency of IL-4-producing-T cell clones observed in CSF demonstrate that T cells which could downregulate the inflammatory process are present in the CNS.

TAP gene transporter polymorphism in inflammatory bowel diseases

BACKGROUND

Many studies suggest the implication of genetic factors in inflammatory bowel diseases. Despite some associations with HLA genes, the lack of definite data may be due to ethnic variations, clinical heterogeneity, or the involvement of additional susceptibility genes beside or within the major histocompatibility complex (MHC), such as TAP genes. The aim of this study was to analyze in patients with ulcerative colitis (UC) or Crohn's disease (CD) the polymorphism of TAP genes that encode the proteins necessary for the transfer of antigenic peptides through the endoplasmic reticulum membrane.

METHODS

One hundred and one UC and 148 CD patients were compared with 173 unrelated healthy controls. Dimorphisms within the TAP1 and TAP2 alleles were analyzed by sequence-specific oligonucleotide typing.

RESULTS

No difference was found between patient groups and controls. However, when CD patients were classified on the basis of their responsiveness to steroid therapy, a significant decrease of TAP2 AA (*0101/*0101) genotype was found in CD patients who did not respond to steroid therapy (22.9% versus 43.7% in steroid responder group; Pc < 0.05; odds ratio = 2.6; 95% confidence limits (CL) = 1.2-5.9). These data appear independent of the distribution of HLA DRB1*01 or DRB1*03 alleles despite a significant linkage disequilibrium between these alleles and TAP2A.

CONCLUSIONS

This result suggests, despite the absence of arguments favoring a genetic susceptibility to CD, that the TAP2 gene or other genes located on chromosome 6 may be involved in the genetic heterogeneity of CD.

Human monocyte-derived macrophages and dendritic cells are comparably effective in vitro in presenting HLA class I-restricted exogenous peptides

Recent experimental data have shown that mice could be immunized efficiently, in particular against cancer, by the injection of antigen-loaded dendritic cells (DC) or macrophages (MPH). In the present work, these two antigen-presenting cells (APC) were prepared in humans from circulating mononuclear cells (MNC). MPH were obtained from MNC that were cultured in hydrophobic plastic bags and purified by elutriation. DC were from the culture of adherent elutriation-purified monocytes in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4). The two APC were prepared in parallel from the same donors and their phenotype and antigen-presenting capacity were compared. DC differed from MPH by a higher expression of HLA-DR and CD23 and a lower expression of CD14, CD64 and of adhesion molecules. DC and MPH were comparably effective in (a) enhancing the mitotic response of autologous lymphocytes to immobilized anti-CD3 (accessory function); (b) presenting melanoma peptides to specific cytotoxic T lymphocyte (CTL) clones; and (c) stimulating the generation of CTL directed against a myxovirus influenza peptide. However, DC were more effective than MPH in inducing the mitotic response of allogeneic peripheral blood leucocytes (PBL), possibly because of their higher expression of HLA class II molecules. In conclusion, DC and MPH prepared from blood MNC did not differ substantially in their ability to activate HLA class I-restricted T-cell responses by exogenous peptide presentation.

Significance of interleukin-1beta and interleukin-1 receptor antagonist genetic polymorphism in inflammatory bowel diseases

OBJECTIVE

Genetic susceptibility to inflammatory bowel disease is well recognized. There is also increasing evidence for the activation of the mucosal immune system and the production of inflammatory cytokines, i.e., interleukin (IL)-1ra and IL-1beta in the inflammatory bowel disease. The aim of this study was to analyze the IL-1beta and IL-1ra gene polymorphism and linkage disequilibrium coefficient between the different alleles of these genes in patients with Crohn's disease (CD) or ulcerative colitis (UC), according to the severity of the disease.

METHODS

Two hundred twenty-eight inflammatory bowel disease patients (87 UC and 141 CD) were included in this study and compared with 113 unrelated controls. The IL-1beta and IL-1ra gene polymorphism was studied after specific amplification of variable regions by PCR. A penta-allelic polymorphism, corresponding to a VNTR region located in intron 2 of the IL-1ra gene, was analyzed, whereas bi-allelic RFLPs displayed by two restriction enzymes (TaqI and AvaI) at position -511 of the IL-1beta gene were analyzed.

RESULTS

There was no significant difference of genotype distribution between controls and CD or UC patients. However, surgically treated UC patients were characterized by a higher frequency of genotype IL-1ra 1-2 (39 vs 16%, pc < 0.01) compared with nonoperated UC patients. Moreover, nonoperated UC patients displayed a lower frequency of IL-1ra allele 2 than surgically treated UC patients (14 vs 34%, pc < 0.002) or controls (14 vs 30%, pc < 0.005). Furthermore, simultaneous analysis of the IL-1beta and IL-1ra genes that are located in the same region of chromosome 2 revealed that CD patients carrying the IL-1beta allele 2 were more often noncarriers of IL-1ra allele 2 (p < 0.005). Moreover, UC and CD patients were, characterized by a lower frequency of the association of IL-1ra allele 2 and IL-1beta allele 2 compared with controls (8.3 vs 20.3% and 10.6 vs 20.3%, p < 0.03).

CONCLUSIONS

IL-1ra and IL-1beta gene polymorphism analysis from a clinical standpoint might help in defining UC prognosis. However, functional studies at both the circulating and mucosal level with stratification on allele associations, especially IL-1ra allele 2-IL-1beta allele 2 subgroups must be realized before therapeutic implications.

Role of HLA-DR-DR and DR-DQ associations in the expression of extraarticular manifestations and rheumatoid factor in rheumatoid arthritis

OBJECTIVE

To investigate the role of HLA-DRB1 genotypes and HLA-DRB1*0401-DQB1*03 haplotypes in the expression of extraarticular manifestations and rheumatoid factor (RF) in rheumatoid arthritis (RA).

METHODS

189 patients with RA were classified according to the presence of vasculitis and seropositivity for RF. IgM RF were determined by at least 2 of the following methods: standard latex agglutination, the Waaler-Rose test, and nephelometry. HLA genotyping was performed by reverse dot blot hybridization for DRB1 alleles and the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method for DQB1 alleles.

RESULTS

The QKRAA susceptibility sequence, which characterizes the HLA-DRB1*0401 allele, was observed in 71.5% of the 21 patients with vasculitis and 57.6% of the 158 RF positive patients. The influence of a 2nd allele within the major histocompatibility complex was observed but the allele differed according to the clinical features examined. Higher risk for vasculitis was observed in patients who carried 2 DRB1 susceptibility alleles, one characterized by the QKRAA sequence and the other by the QRRAA sequence (OR = 3). Conversely, the higher risk for IgM RF positivity was observed in patients who carried the QKRAA sequence of the DRB1 alleles with the DQB1*0301 alleles of the DQ region (OR = 4.7).

CONCLUSION

Our data suggest that a distinct immunogenetic association is involved in the extraarticular manifestations of RA and in the expression of RF.

Survival, proliferation, and functions of porcine hepatocytes encapsulated in coated alginate beads: a step toward a reliable bioartificial liver

Orthotopic liver transplantation is the most effective treatment for fulminant hepatic failure. As an alternative treatment, an efficient extracorporeal bioartificial liver should contain a large yield of functional hepatocytes with an immunoprotective barrier, for providing temporary adequate metabolic support to allow spontaneous liver regeneration or for acting as a bridge toward transplantation. Survival, proliferation, and functions of porcine hepatocytes were evaluated in primary cultures and after embedding in alginate beads, which were subsequently coated with a membrane made by a transacylation reaction between propylene glycol alginate and human serum albumin. Disruption of total pig livers by collagenase perfusion/recirculation allowed the obtention of up to 10(11) hepatocytes with a viability greater than 95%. Hepatocytes in conventional cultures or embedded in coated alginate beads survived for about 10 days, secreted proteins, particularly albumin, and maintained several phase I and II enzymatic activities, namely ethoxyresorufin-O-deethylase, oxidation of nifedipine to pyridine, phenacetin deethylation to paracetamol, glucuroconjugation of paracetamol, and N-acetylation of procainamide. Typical features of mitosis and [3H]thymidine incorporation indicated that porcine hepatocytes proliferated in both conventional cultures and alginate beads. The efficacy of the membrane surrounding alginate beads for protecting cells from immunoglobulins was tested by embedding HLA-typed human lymphocytes, which were subsequently incubated with specific anti-HLA immunoglobulin G and complement. These data show that large yields of porcine hepatocytes that are embedded in coated alginate beads remain functional and are isolated from large molecular weight molecules, such as immunoglobulins. This system represents a promising tool for the design of an extracorporeal bioartificial liver, containing xenogeneic hepatocytes, to treat acute liver disease in humans.