Browsing by Author "Anderson, Suzanne"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- ItemOpen AccessCCL3L1 copy number, CCR5 genotype and susceptibility to tuberculosis(2014-01-09) Carpenter, Danielle; Taype, Carmen; Goulding, Jon; Levin, Mike; Eley, Brian; Anderson, Suzanne; Shaw, Marie-Anne; Armour, John AAbstract Background Tuberculosis is a major infectious disease and functional studies have provided evidence that both the chemokine MIP-1α and its receptor CCR5 play a role in susceptibility to TB. Thus by measuring copy number variation of CCL3L1, one of the genes that encode MIP-1α, and genotyping a functional promoter polymorphism -2459A > G in CCR5 (rs1799987) we investigate the influence of MIP-1α and CCR5, independently and combined, in susceptibility to clinically active TB in three populations, a Peruvian population (n = 1132), a !Xhosa population (n = 605) and a South African Coloured population (n = 221). The three populations include patients with clinically diagnosed pulmonary TB, as well as other, less prevalent forms of extrapulmonary TB. Methods and results Copy number of CCL3L1 was measured using the paralogue ratio test and exhibited ranges between 0–6 copies per diploid genome (pdg) in Peru, between 0–12 pdg in !Xhosa samples and between 0–10 pdg in South African Coloured samples. The CCR5 promoter polymorphism was observed to differ significantly in allele frequency between populations (*A; Peru f = 0.67, !Xhosa f = 0.38, Coloured f = 0.48). Conclusions The case–control association studies performed however find, surprisingly, no evidence for an influence of variation in genes coding for MIP-1α or CCR5 individually or together in susceptibility to clinically active TB in these populations.
- ItemOpen AccessPolymorphic variation in TIRAP is not associated with susceptibility to childhood TB but may determine susceptibility to TBM in some ethnic groups(Public Library of Science, 2009) Dissanayeke, Shobana Rebecca; Levin, Samuel; Pienaar, Sandra; Wood, Kathryn; Eley, Brian; Beatty, David; Henderson, Howard; Anderson, Suzanne; Levin, MichaelHost recognition of mycobacterial surface molecules occurs through toll like receptors (TLR) 2 and 6. The adaptor protein TIRAP mediates down stream signalling of TLR2 and 4, and polymorphisms in the TIRAP gene ( TIRAP ) have been associated with susceptibility and resistance to tuberculosis (TB) in adults. In order to investigate the role of polymorphic variation in TIRAP in childhood TB in South Africa, which has one of the highest TB incidence rates in the world, we screened the entire open reading frame of TIRAP for sequence variation in two cohorts of childhood TB from different ethnic groups (Xhosa and mixed ancestry). We identified 13 SNPs, including seven previously unreported, in the two cohorts, and found significant differences in frequency of the variants between the two ethnic groups. No differences in frequency between individual SNPs or combinations were found between TB cases and controls in either cohort. However the 558C→T SNP previously associated with TB meningitis (TBM) in a Vietnamese population was found to be associated with TBM in the mixed ancestry group. Polymorphisms in TIRAP do not appear to be involved in childhood TB susceptibility in South Africa, but may play a role in determining occurrence of TBM.
- ItemOpen AccessTuberculosis and genes of the IL12/IL23/IFNγ pathway: Exploring functional significance of novel mutations in the IL12p40 promoter(2014) Pienaar, Sandra Margaret; Eley, Brian; Anderson, SuzanneThe aim of this work was to screen the IL12p40 gene promoter for association with TB disease. Initially a subcohort of children (TB cases and healthy controls) from a TB-endemic area was screened for DNA changes by the WAVE method. Thereafter, the entire paediatric cohort and a cohort of healthy adult controls were screened by Amplification Refractory Mutation System PCR. Functional testing was done by reporter assay and immunological phenotype was investigated by measurement of cytokines levels and cytokine receptor expression. WAVE screening identified two heterozygous SNPs, -1523 A/G and -1564 C/T. Statistical analysis showed that -1523 A/G may be protective against TB disease (p=0.02). This possibility was supported by the location of -1523 A/G occurring within a GTATA sequence reported to bind nuclear proteins. Specific ARMS-PCR assays were then designed for screening of additional paediatric subjects and healthy adult controls for these SNPs. Analysis of the larger group, showed that -1564 C/T may contribute to susceptibility to TB disease (p=0.03) Exploring functional relevance, normal and mutant promoter fragments were PCR amplified, using uniquely adapted primers that included restriction sites corresponding to those in the multiple cloning site of an expression vector, facilitating cloning. A truncated promoter and one with essential regions deleted, were created as negative controls. These five promoter fragments were cloned into the expression vector and functional differences tested by reporter. No significant functional differences between variant and normal promoter fragments were observed. A predictive immune phenotype was investigated by measurement of IFNγ, TNFα and IL12p70 cytokine levels and IL12βR1 receptor expression. While distinct patterns of cytokine responses were seen, these did not predict genotype. These results show that the IL12p40 gene promoter is highly conserved and sequence variants may be just one of many factors contributing to TB susceptibility.