Biomedical subjects

Dorian McIlroy

Publications and source records attributed to Dorian McIlroy.

6 recordsLinked to original sources

PubMed2005

Profiling dendritic cell maturation with dedicated microarrays.

Dendritic cell (DC) maturation is the process by which immature DC in the periphery differentiate into fully competent antigen-presenting cells that initiate the T cell response. However, DC respond to many distinct maturation stimuli, and different types of mature DC induce qualitatively different T cell responses. As DC maturation involves the coordinated regulation of hundreds of genes, comprehensive assessment of DC maturation status would ideally involve monitoring the expression of all of these transcripts. However, whole-genome microarrays are not well-suited for routine phenotyping of DC, as the vast majority of genes represented on such chips are not relevant to DC biology, and their cost limits their use for most laboratories. We therefore developed a DC-dedicated microarray, or "DC Chip", incorporating probes for 121 genes up-regulated during DC maturation, 93 genes down-regulated during maturation, 14 DC-specific genes, and 90 other genes with known or probable immune functions. These microarrays were used to study the kinetics of DC maturation and the differences in maturation profiles among five healthy donors after stimulation with tumor necrosis factor-alpha + polyI:C. Results obtained with the DC Chip were consistent with flow cytometry, enzyme-linked immunosorbent assay, and real-time polymerase chain reaction, as well as previously published data. Furthermore, the coordinated regulation of a cluster of genes (indoleamine dioxygenase, kynureninase, kynurenine monoxygenase, tryptophanyl tRNA synthetase, and 3-hydroxyanthranilate 3,4-dioxygenase) involved in tryptophan metabolism was observed. These data demonstrate the use of the DC Chip for monitoring the molecular processes involved in the orientation of the immune response by DC.

Antigens, CD↗

PubMed2005

FAS promoter polymorphisms correlate with activity grade in hepatitis C patients.

OBJECTIVE: Hepatocytes are susceptible to FAS-mediated apoptosis. The impact of polymorphisms in the FAS gene on histopathological features of HCV infection was therefore investigated. DESIGN/METHODS: Three single-nucleotide polymorphisms in the FAS promoter were assessed in 190 patients with chronic hepatitis C. Associations between FAS haplotypes and fibrosis stage and activity grade were tested by univariate and multivariate analyses. RESULTS: While there was no correlation between FAS promoter genotype and fibrosis stage, patients carrying the GCA haplotype (P=0.03, Fisher's exact test) and those homozygous for the GTG haplotype (P = 0.06) tended to have lower activity scores. Logistic regression showed that these associations were independent of patient age, sex and alcohol consumption. In a logistic regression model incorporating only male gender (odds ratio 2.1, 95% confidence interval 1.1-4.1 P = 0.04), the presence of the GCA haplotype (OR 0.31 95% CI 0.13-0.78 P = 0.01), and GTG homozygosity (OR 0.26 95% CI 0.08-0.83 P = 0.02), all three factors were independently correlated with activity grade. Furthermore, the GTG haplotype appeared to have lower promoter activity than the wild type GTA haplotype in a hepatocellular carcinoma cell line. CONCLUSIONS: Genetic polymorphism in the FAS gene may account for some of the histopathological variability in chronic hepatitis C.

Adult↗

PubMed2003

Optimizing dendritic cell-based anticancer immunotherapy: maturation state does have clinical impact.

Tumour immunotherapy using dendritic cells (DCs) is a new therapeutic approach, which has been applied to a variety of different cancers over the last 5 years. Here we discuss the clinical results of these trials in relation to the different protocols used to generate DCs, and in particular the effect that DC maturation state has had on clinical responses. In ten different melanoma trials a total of 167 patients have been treated, resulting in 9 complete tumour regressions, 24 partial regressions, 26 patients with stable disease, and 108 with progressive disease. Favourable response, defined as any outcome other than progressive disease, was not associated with previous chemotherapy, but was significantly correlated ( p<0.001) with the addition of TNF-alpha for the maturation of DCs in vitro. Hence DC maturation state has had an impact on clinical responses to therapy. However, TNF-alpha is not the only molecule capable of inducing DC maturation, and strategies for improving clinical responses by optimizing DC maturation are discussed.

Antineoplastic Agents↗

PubMed2003

Transient exposure of dendritic cells to maturation stimuli is sufficient to induce complete phenotypic maturation while preserving their capacity to respond to subsequent restimulation.

Dendritic cells (DC) are activated by pathogens, cytokines and activated T cells. We investigated the impact of a transient initial DC stimulation on the kinetics of maturation using a combination of double-stranded RNA and TNFalpha and subsequent restimulation by T cell-derived stimuli. Transient stimulation of DC was sufficient to start an irreversible program of phenotypic maturation which proceeded in the absence of the initial stimulus. Transiently stimulated DC secreted lower amounts of IL-12 during the 48-h period of the first stimulation than cells activated for 48 h. Although both DC preparations expressed the same level of maturation-associated markers at 48 h, DC stimulated for shorter periods preserved higher sensitivity to boosting upon subsequent stimulation by T cell-derived signals. We showed that DC initially stimulated for shorter periods were more potent stimulators of T lymphocytes and they induced a more polarized Th1 response. These results indicate that short exposure of DC to maturation stimuli enables an efficient defensive immune response induction by differentially regulating phenotypic maturation and cytokine production of DC.

Antigen Presentation↗

PubMed2003

A triple-mutated allele of granzyme B incapable of inducing apoptosis.

Granzyme B (GzmB) is a serine protease involved in many pathologies, including viral infections, autoimmunity, transplant rejection, and antitumor immunity. To measure the extent of genetic variation in GzmB, we screened the GzmB gene for polymorphisms and defined a frequently represented triple-mutated GzmB allele. In this variant, three amino acids of the mature protein Q(48)P(88)Y(245) are mutated to R(48)A(88)H(245). In CD8(+) cytotoxic T lymphocytes, GzmB was expressed at similar levels in QPY homozygous, QPY/RAH heterozygous, and RAH homozygous individuals, demonstrating that RAH GzmB is a stable protein. Active RAH GzmB expressed in glioblastoma cell lines displayed proteolytic activity, but in contrast to QPY GzmB, it did not accumulate in the nucleus and was unable to induce Bid cleavage, cytochrome c release, or apoptosis. Molecular modeling showed that the three amino acid substitutions clustered near the C-terminal alpha-helix of the protein, indicating that this region of the protein may be involved in the intracellular targeting of GzmB. The triple-mutated GzmB allele that we describe appears to be incapable of inducing apoptosis in tumor cell lines, and its presence could, therefore, influence both the prognosis of cancer patients and the success rates of antitumor cellular immunotherapy.

Alleles↗

PubMed2002

Protective effect of interleukin-4 -589T polymorphism on human immunodeficiency virus type 1 disease progression: relationship with virus load.

The interleukin (IL)-4 -589T allele bears a single nucleotide polymorphism at position -589 upstream from the open-reading frame of the IL-4 gene. To determine the influence of this allele on human immunodeficiency virus (HIV) type 1 disease, disease progression and serum virus load were assessed by IL-4 genotype in 427 white patients with known seroconversion dates who were followed in the French SEROCO cohort between 1988 and 1996. Serum virus load was 0.20 log lower during the 6-24-month plateau phase after seroconversion in patients with IL-4 -589T than in those without this allele (P=.02). Kaplan-Meier analysis survival curves showed a slower progression to clinical AIDS in carriers of IL-4 -589T (P=.04). Adjustment for early serum virus load greatly diminished the strength of this association. These results suggest that IL-4 -589T protects against HIV-1 disease progression by reducing virus load.

Acquired Immunodeficiency Syndrome↗