William M. Howell

Gene polymorphisms, inflammatory diseases and cancer.

Genes whose products play a critical role in regulation of the immune response include the human leucocyte antigen (HLA) and cytokine families of genes. The HLA genes are the most polymorphic found in the human genome, and the bulk of this polymorphism results in functional differences in expressed HLA molecules, resulting in inter-individual differences in presentation of peptide antigens to T-cells. In addition, a considerable number of cytokine-associated gene polymorphisms have been identified, the bulk of which occur in the upstream promoter sequences of these genes, which in many cases results in differential in vitro expression of the respective pro- or anti-inflammatory gene product. Particular HLA polymorphisms result in well-defined associations with a large number of immunologically-mediated diseases, including some diseases with known dietary risk factors. For example, individuals of HLA-DQA1*0501, DQB1*0201 genotype have a greater than 200-fold increased risk of developing intolerance to dietary wheat gluten (coeliac disease), and additional HLA-related factors may influence the development of malignant lymphoma within pre-existing coeliac disease. Similarly, HLA-DRB1 alleles sharing a common sequence motif constitute the primary known genetic risk factor for rheumatoid arthritis. The influence of polymorphisms associated with differential cytokine expression on disease susceptibility is currently of much interest. Most attention has been focused on associations with susceptibility to benign immunologically-mediated diseases, including a number of gut diseases. However, recent work from our laboratory indicates that cytokine polymorphisms may influence susceptibility to and prognosis in a number of different cancers, including malignant melanoma skin cancer and solid tumours which may be influenced by diet, such as prostate cancer (collaboration with the CRC/BPG UK Familial Prostate Cancer study). In addition, preliminary work suggests that dietary modulation of expression levels of certain cytokines in healthy human subjects may be genotype dependent.

Interleukin-2 is found in the synovium of psoriatic arthritis and spondyloarthritis, not in rheumatoid arthritis

Objective of this project was to determine whether synovial expression of interleukin-2 (IL-2) in arthritis is a disease-specific phenomenon. Immunohistological examination of needle biopsies from 7 rheumatoid arthritis (RA) patients never exposed to disease modifying antirheumatic drugs (DMARDs), 13 RA patients on DMARDs, 4 patients with seronegative spondyloarthritis (SpA), and 5 psoriatic arthritis (PsA) patients. Biopsies were either snap-frozen immediately or cultured for 48 hr, with and without phytohaemagglutinin (PHA) prior to APAAP staining. In snap-frozen biopsies, IL-2 was detected in none of 18 RA samples with significant T cell infiltrates. In contrast, IL-2 was seen in 7/9 PsA/SpA samples. After culture without PHA, IL-2 was detected in 0/14 RA and 5/6 PsA/SpA samples; with PHA, IL-2 was present in 1/14 RA and 2/2 PsA/SPA samples. Synovial IL-2 protein expression appears to distinguish between RA (absent) and PsA/SpA (present). This may reflect a difference in pathophysiology between these diseases.

Genotypic Heterogeneity of Node Based Peripheral T-cell Lymphoma

PTCL represents a diverse group of histological entities that defy classification schemes based on normal T cell differentiation, differ in their clinical presentation and behave unpredictably. Genetic analyses of this phenotypically heterogeneous group have clearly shown that histologically defined PTCL may be subdivided on the basis of clonal gene rearrangements. The absence of clonal gene rearrangements in a significant proportion of PTCL cases has increased the complexity of classification. The data presented in this review suggest that a molecular classification would allow true reflection of PTCL aetiology, but carefully coordinated studies are required to evaluate the clinical usefulness of such a classification scheme.

RRR-alpha-tocopherol supplementation has pro- and anti-inflammatory and pro- and antioxidant effects in peripheral blood mononuclear cells in healthy middle-aged men depending upon dosage and genotype for xenobiotic metabolising enzymes

In healthy individuals, glucose and fatty acids are substrates for ATP generation in the heart. There is emerging evidence from patients with type 2 diabetes mellitus that preferential use of fatty acid b-oxidation for energy production may be linked to cardiomyopathy (Fink, 2004). PPARa activity is important for regulating fatty acid b-oxidation in the heart and is increased in hearts of rats with experimentally induced diabetes (Fink, 2004). Prenatal undernutrition is related inversely to risk of type 2 diabetes mellitus in man (Poole & Byrne, 2005) and insulin resistance in rats (Bertram & Hanson, 2001). We have shown that maternal dietary protein restriction induces persistent alterations to hepatic and carbohydrate metabolism in the offspring by altering the epigenetic regulation of PPARa and the glucocorticoid receptor (GR) (Lillycrop et al. 2005). Here we have tested the hypothesis that prenatal protein restriction induces hypomethylation of the GR and PPARa promoters in the heart, and that this is prevented by supplementation of the protein-restricted (PR) diet with folic acid.Induction of a modified metabolic phenotype in the offspring by feeding a protein-restricted (PR) diet during pregnancy in the rat involves DNA hypomethylation and altered covalent histone modifications leading to increased expression of specific genes (Lillycrop et al. 2005a,b). Hypomethylation of gene promoters may be achieved by impaired DNA methylation de novo, loss of CpG methylation during mitosis, or active demethylation. Histone modifications which modulate transcription involve binding of methyl CpG binding protein (MeCP)-2 to methylated DNA and recruitment of histone-modifying enzymes (Bird, 2002). We investigated in the offspring the effect of feeding a PR diet during pregnancy on the expression of hepatic DNA methyltransferase (DMNT) 1 which maintains CpG methylation, DNMT 3a and 3b which catalyse DNA methylation de novo and the DNA demethylase MBD2.

Influence of superoxide dismutase polymorphism and overweight status on clinical outcome and oxidant production and stress in healthy middle-aged men and rheumatoid patients receiving high-dose RRR-alpha-tocopherol supplementation

In healthy individuals, glucose and fatty acids are substrates for ATP generation in the heart. There is emerging evidence from patients with type 2 diabetes mellitus that preferential use of fatty acid b-oxidation for energy production may be linked to cardiomyopathy (Fink, 2004). PPARa activity is important for regulating fatty acid b-oxidation in the heart and is increased in hearts of rats with experimentally induced diabetes (Fink, 2004). Prenatal undernutrition is related inversely to risk of type 2 diabetes mellitus in man (Poole & Byrne, 2005) and insulin resistance in rats (Bertram & Hanson, 2001). We have shown that maternal dietary protein restriction induces persistent alterations to hepatic and carbohydrate metabolism in the offspring by altering the epigenetic regulation of PPARa and the glucocorticoid receptor (GR) (Lillycrop et al. 2005). Here we have tested the hypothesis that prenatal protein restriction induces hypomethylation of the GR and PPARa promoters in the heart, and that this is prevented by supplementation of the protein-restricted (PR) diet with folic acid.Induction of a modified metabolic phenotype in the offspring by feeding a protein-restricted (PR) diet during pregnancy in the rat involves DNA hypomethylation and altered covalent histone modifications leading to increased expression of specific genes (Lillycrop et al. 2005a,b). Hypomethylation of gene promoters may be achieved by impaired DNA methylation de novo, loss of CpG methylation during mitosis, or active demethylation. Histone modifications which modulate transcription involve binding of methyl CpG binding protein (MeCP)-2 to methylated DNA and recruitment of histone-modifying enzymes (Bird, 2002). We investigated in the offspring the effect of feeding a PR diet during pregnancy on the expression of hepatic DNA methyltransferase (DMNT) 1 which maintains CpG methylation, DNMT 3a and 3b which catalyse DNA methylation de novo and the DNA demethylase MBD2.