Suzy Teutsch

Identification of 11 novel and common single nucleotide polymorphisms in the interleukin-7 receptor-|[alpha]| gene and their associations with multiple sclerosis

We have investigated the interleukin-7 receptor (IL-7R) α-chain gene as a positional and functional candidate gene for susceptibility to multiple sclerosis (MS), in view of its chromosomal location on 5p14–p12, a region that has shown suggestive linkage in MS genome screens, and its role in T- and B-cell proliferation and reactivity. Amplification and DNA sequencing of the IL-7Rα gene in pooled and individual samples identified 13 single nucleotide polymorphisms (SNPs), 11 of which are novel, including three in the promoter region, three in exons encoding amino-acid changes (ACC(Thr)66ATC(Ile), ATC(Ile)244ACC(Thr), ATC(Ile)336GTC(Val)), four in introns and one in the 3′ untranslated region. Four IL-7R haplotypes were identified for nine SNPs, showing linkage disequilibrium across the gene, and allowing haplotype frequency determination from just three of the nine SNPs. Genotyping of the −504 polymorphism in 101 MS and 90 controls showed a suggestive (P=0.1) association of the T allele with MS; however, this was not supported by transmission disequilibrium testing in 186 MS trio families (P=0.8). There were trends towards an increase of the GTG+ haplotype (odds ratio=1.45), and under-representation of the TTA+ haplotype (OR=0.65) in DRB1*1501-positive MS cases, suggesting that larger sample sizes and comparison in more defined MS patient groups may support an association with the IL-7R gene. These polymorphisms would also be useful for studying genetic associations with other immunologic diseases.

The CCR5 Deletion Mutation Fails to Protect Against Multiple Sclerosis

Recent advances in the understanding and identification of chemokines and their receptors have provided evidence for their consideration as candidate loci with respect to genetic susceptibility/resistance to MS. Increased levels of the chemokine, macrophage inflammatory protein (MIP)-1 alpha, have been demonstrated in the cerebrospinal fluid of both patients with MS and mice with EAE, and anti-MIP-1 alpha antibodies have been shown to prevent EAE. Recently, a common deletion mutation in the gene for the major receptor for MIP-1 alpha, chemokine receptor 5 (CCR5) has been described. Homozygotes for the mutation fail to express this receptor. Moreover, homozygotes are highly protected against HIV infection this has potential implications for the cell entry of infectious agents in other multifactorial disease where a viral component may be involved. In view of these aspects, a group of 120 unrelated Australian relapsing remitting MS and 168 unrelated control subjects were screened for the CCR5 delta 32 mutation. There was no significant difference in the allele frequency of CCR5 delta 32 gene between the MS patients (0.1125) and the control population (0.0921). The presence of two CCR5 delta 32 homozygotes in the MS patients indicates that the absence of CCR5 is not protective against MS. These data suggest that CCR5 is not an essential component in MS expression, though this may be due to redundancy in the chemokine system where different chemokine receptors may substitute for CCR5 when it is absent.

Incidence of primary hepatitis C infection and risk factors for transmission in an Australian prisoner cohort

BackgroundHepatitis C virus (HCV) infection is common in prisoner populations, particularly those with a history of injecting drug use (IDU). Previous studies of HCV incidence have been based on small case numbers and have not distinguished risk events in prison from those in the community.MethodsHCV incidence was examined in a longitudinal cohort of 488 Australian prisoners with a history of IDU and documented to be seronegative within 12 months prior to enrolment. Inmates were tested for anti-HCV antibodies and viremia, and interviewed about demographic and behavioral risk factors for transmission.ResultsThe cohort was predominantly male (65%) with high rates of prior imprisonment (72%) and tattooing (73%), as well as longstanding IDU (mean 8.5 years). Ninety-four incident HCV cases were identified (incidence 31.6 per 100 person years). Independent associations were observed between incident infection and prior imprisonment (p = 0.02) and tattooing (p = 0.03), and surprisingly also with methadone maintenance treatment (MMT) (p < 0.001).ConclusionsHigh rates of new HCV infection were found in this prisoner cohort reflecting their substantive risk behavior profile, despite having remained uninfected for many years. The association with MMT is challenging and highlights the need for better understanding of prison-specific HCV transmission risks, as well as the uptake and effectiveness of prevention programs.

Association of common T cell activation gene polymorphisms with multiple sclerosis in Australian patients

Susceptibility to multiple sclerosis (MS) may be influenced by the interaction of several genes within a biological pathway. T cell activation and costimulation may be potentially important in MS pathogenesis. We have therefore investigated associations between MS and polymorphisms in the CD152 (CTLA-4), CD28, CD80 and CD86 genes in Australian patients. We found no significant MS association with CTLA-4 exon 1 +49 alleles, and meta-analysis showed no significant association across nine comparable datasets (OR=1.04, p=0.54), nor with primary progressive MS across seven datasets (OR=1.19, p=0.21). Haplotype analysis showed a trend towards a decrease of the CTLA-4-1722C, -1577G, +49G haplotype in +49 G positive MS patients compared with controls (p=0.06). Screening of CD28, CD80 and CD86 genes identified novel polymorphisms in the putative promoter regions of CD28 (-372 G/A) and CD86 (exon 2 -359 deletionAAG). There was a significant increase of the CD28 -372 G allele frequency in MS patients vs. controls (p=0.045) and a trend towards a significant interaction between this allele and the CTLA-4 +49 G allele (OR=4.00, p=0.058). Our results suggest that the CTLA-4 +49 alone is not associated with overall susceptibility to MS, but may be important in clinical subsets of patients and/or may interact epistatically with other gene polymorphisms.

Plasma interferon‐gamma‐inducible protein‐10 (IP‐10) levels during acute hepatitis C virus infection

Systemic levels of interferon‐gamma‐inducible protein‐10 (IP‐10) are predictive of treatment‐induced clearance in chronic hepatitis C virus (HCV). In the present study, factors associated with plasma IP‐10 levels at the time of acute HCV detection and the association between IP‐10 levels and spontaneous clearance were assessed in three cohorts of acute HCV infection. Among 299 individuals, 245 (181 male, 47 human immunodeficiency virus‐positive [HIV+]) were HCV RNA+ at acute HCV detection. In adjusted analysis, factors independently associated with IP‐10 levels ≥150 pg/mL (median level) included HCV RNA levels >6 log IU/mL, HIV coinfection and non‐Aboriginal ethnicity. Among 245 HCV RNA+ at acute HCV detection, 214 were untreated (n = 137) or had persistent infection (infection duration ≥26 weeks) at treatment initiation (n = 77). Spontaneous clearance occurred in 14% (29 of 214). Individuals without spontaneous clearance had significantly higher mean plasma IP‐10 levels at the time of acute HCV detection than those with clearance (248 ± 32 versus 142 ± 22 pg/mL, P = 0.008). The proportion of individuals with spontaneous clearance was 0% (0 of 22, P = 0.048) and 16% (27 of 165) and in those with and without plasma IP‐10 levels ≥380 pg/mL. In adjusted analyses, favorable IL28B genotype was associated with spontaneous clearance, while higher HCV RNA level was independently associated with lower odds of spontaneous clearance. Conclusion: High IP‐10 levels at acute HCV detection were associated with failure to spontaneously clear HCV. Patients with acute HCV and high baseline IP‐10 levels, particularly >380 pg/mL, should be considered for early therapeutic intervention, and those with low levels should defer therapy for potential spontaneous clearance. (HEPATOLOGY 2013;)

A prospective study of hepatitis C incidence in Australian prisoners

AIMS To document the relationships between injecting drug use, imprisonment and hepatitis C virus (HCV) infection. DESIGN Prospective cohort study. SETTING Multiple prisons in New South Wales, Australia. PARTICIPANTS HCV seronegative prisoners with a life-time history of injecting drug use (IDU) were enrolled and followed prospectively (n = 210) by interview and HCV antibody and RNA testing 6-12-monthly for up to 4 years when in prison. MEASUREMENTS HCV incidence was calculated using the person-years method. Cox regression was used to identify predictors of incident infection using time-dependent covariates. RESULTS Almost half the cohort reported IDU during follow-up (103 subjects; 49.1%) and 65 (31%) also reported sharing of the injecting apparatus. There were 38 HCV incident cases in 269.94 person-years (py) of follow-up with an estimated incidence of 14.08 per 100 py [confidence interval (CI) = 9.96-19.32]. Incident infection was associated independently with Indigenous background, injecting daily or more and injecting heroin. Three subjects were RNA-positive and antibody-negative at the incident time-point, indicating early infection, which provided a second incidence estimate of 9.4%. Analysis of continuously incarcerated subjects (n = 114) followed over 126.73 py, identified 13 new HCV infections (10.26 per 100 py, CI = 5.46-17.54), one of which was an early infection case. Bleach-cleansing of injecting equipment and opioid substitution treatment were not associated with a significant reduction in incidence. CONCLUSIONS In New South Wales, Australia, imprisonment is associated with high rates of hepatitis C virus transmission. More effective harm reduction interventions are needed to control HCV in prison settings.

Transmission of Hepatitis C Virus among Prisoners, Australia, 2005-2012.

Ongoing transmission is associated with drug injection.

The DRB1 Val86/Val86genotype associates with multiple sclerosis in Australian patients

Genetic susceptibility to multiple sclerosis (MS) has so far been strongly localized to the MHC class II region encoding the alleles of the haplotype HLA-DRB1*1501, -DQA1*0102, -DQB1*0602. However, this haplotype is not carried by approximately 40% of MS patients; a potential explanation could be that they carry other MHC class II alleles with similar function due to the sharing of nucleotide sequences encoding critical amino acid residues. The DRB1 gene is polymorphic at residue 86, encoding valine or glycine. In view of the increasing evidence for a functional role for DRB1 aa86 in the binding and presentation of autoantigenic peptides such as myelin basic protein, this study investigated associations with the residue 86 polymorphism in an Australian MS population. A significant increase in the Val86/Val86 genotype was observed in the MS patients, which was still present in the absence of the DRB1*1501 allele (p = 0.032). This suggest that DRB1 aa86 may have an independent role in contributing to MS susceptibility. The Val86/Val86 genotype was correlated with genotyping for other putative MS susceptibility genes, including T cell receptor beta chain germline polymorphisms, HLA-DMB alleles, and -DQA1 and -DQB1 alleles encoding critical amino acid residues, with a significant interaction only observed with DQB1 Leu26 (p = 0.014). Additional studies of the HLA-DRB1 aa86 polymorphism in MS, and its function, are needed to more fully understand this association.

HLA-DMB gene and HLA-DRA promoter region polymorphisms in Australian multiple sclerosis patients.

The MHC region has been shown to contain a susceptibility locus for multiple sclerosis (MS). While the strongest association to date has been between HLA-DRB1*1501 and MS, the exact nature of the MHC association in MS remains unclear. Two candidate polymorphic loci within the MHC class II region, the HLA-DMB gene and the HLA-DRA promoter, which lie close to HLA-DRB1, were therefore examined in an Australian MS population. The HLA-DMB*0103 phenotype was increased in the MS patients (46% vs. 30%) and the frequency of the HLA-DRA promoter A allele was also increased (81% vs. 68%). When the subjects were stratified into HLA-DRB*1501 positive and negative individuals these associations were not significantly different. This is a result of the strong linkage disequilibrium between HLA-DRB*1501 and both HLA-DMB*0103 and the HLA-DRA promoter A allele. The complete linkage between DRB1*1501 and the HLA-DRA promoter A allele indicates that the MS susceptibility haplotype (DRB1*1501-HLA-DQB1*0602-HLA-DQA1* 0102) can be extended out to promoter of the HLA-DRA locus. Interactions between both HLA-DMB and the HLA-DRA promoter and other reported MS susceptibility loci were examined (TCRBV polymorphisms, HLA-DQA1 and HLA-DQB1). Some interactions between specific TCRBV polymorphisms and the HLA-DRA promoter were observed, which is consistent with other published reports suggesting an epistatic interaction between TCRBV and HLA-DRB1.

Canine fucosidosis: a model for retroviral gene transfer into haematopoietic stem cells

Severe progressive fatal neurological degeneration occurs in fucosidosis, a storage disease. Bone marrow transplantation into affected dogs has shown that haematopoietic stem cells can provide enzyme producing daughter cells to the central nervous system, altering disease course. This makes canine fucosidosis an ideal large animal model for gene therapy. Fucosidosis affected allogeneic or autologous canine marrow was transduced ex vivo by cocultivation, then transplanted into fucosidosis affected dogs conditioned with total lymphoid irradiation. The vectors were Moloney murine leukaemia virus based. Transduction efficiency was increased with multiple cytokines in short term marrow culture. Despite high levels of transduction, proviral sequence was detected 2 months post transplant in only one dog. Early or total graft failure occurred in all transplants. We believe lack of engraftment could be caused by differentiation or change of repopulating ability of marrow cells occurring with multiple cytokine mixes in culture media.