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Dermot P B McGovern

Publications and source records attributed to Dermot P B McGovern.

11 recordsLinked to original sources
PubMed2024

Macrophage LRRK2 hyperactivity impairs autophagy and induces Paneth cell dysfunction.

LRRK2 polymorphisms (G2019S/N2081D) that increase susceptibility to Parkinson's disease and Crohn's disease (CD) lead to LRRK2 kinase hyperactivity and suppress autophagy. This connection suggests that LRRK2 kinase inhibition, a therapeutic strategy being explored for Parkinson's disease, may also benefit patients with CD. Paneth cell homeostasis is tightly regulated by autophagy, and their dysfunction is a precursor to gut inflammation in CD. Here, we found that patients with CD and mice carrying hyperactive LRRK2 polymorphisms developed Paneth cell dysfunction. We also found that LRRK2 kinase can be activated in the context of interactions between genes (genetic autophagy deficiency) and the environment (cigarette smoking). Unexpectedly, lamina propria immune cells were the main intestinal cell types that express LRRK2, instead of Paneth cells as previously suggested. We showed that LRRK2-mediated pro-inflammatory cytokine release from phagocytes impaired Paneth cell function, which was rescued by LRRK2 kinase inhibition through activation of autophagy. Together, these data suggest that LRRK2 kinase inhibitors maintain Paneth cell homeostasis by restoring autophagy and may represent a therapeutic strategy for CD.

Leucine-Rich Repeat Serine-Threonine Protein Kinas↗
PubMed2006

TUCAN (CARD8) genetic variants and inflammatory bowel disease.

BACKGROUND & AIMS: The identification of the association between Crohn's disease (CD) and NOD2 (CARD15) confirmed both the heritability of CD and highlighted the role of the nuclear factor kappaB (NFkappaB) pathway in disease pathogenesis. Other susceptibility loci exist. TUCAN (CARD8) is located beneath a CD peak of linkage on chromosome 19q. TUCAN is expressed in the gut and is a negative regulator of NFkappaB, making it an excellent candidate gene for gastrointestinal inflammation. METHODS: Ten single nucleotide polymorphisms (SNP) across TUCAN were genotyped in 365 controls, 372 patients with CD, and 373 patients with ulcerative colitis. A diagnostic panel for CD was constructed using smoking status and TUCAN, NOD2, IBD5, NOD1, and TNFSF15 data. RESULTS: We demonstrate significant association between a TUCAN SNP and CD (OR 1.35, P = .0083). The association was more pronounced with disease affecting sites other than the colon (odds ratio, 1.52) and NOD2-negative CD (odds ratio, 1.50). Combination of these data with smoking and NOD2, IBD5, NOD1, and TNFSF15 status demonstrated very strong associations with CD and high sensitivities (96.3%), specificities (99.4%), and likelihood ratios (12.8) for CD, although further work will be needed before this model can be translated into direct clinical utility. CONCLUSIONS: We have shown an association between a likely functional polymorphism in TUCAN and CD. The combination of these data in a genetic panel suggests that clinicians may soon be able to translate genetic advances into direct benefits for patients.

CARD Signaling Adaptor Proteins↗
PubMed2005

Association between a complex insertion/deletion polymorphism in NOD1 (CARD4) and susceptibility to inflammatory bowel disease.

The identification of the role of genetic variants within NOD2 (CARD15) in Crohn's disease and ulcerative colitis susceptibility highlight the role of the innate immune system in inflammatory bowel disease (IBD) pathogenesis. NOD1 (CARD4) is located on chromosome 7p14.3, in a region of known linkage to IBD and encodes an intracellular bacterial pathogen-associated molecular pattern receptor that is closely related to NOD2. We have identified strong association between haplotypes in the terminal exons of NOD1 and IBD (multi-allelic P = 0.0000003) in a panel of 556 IBD trios. The deletion allele of a complex functional NOD1 indel polymorphism (ND(1) + 32656*1) was significantly associated with early-onset IBD (P = 0.0003) in unrelated cases and controls. ND1 + 32656*1 was also associated with extra-intestinal manifestations of IBD (P = 0.04). These findings in two independent populations provide strong evidence for a role for NOD1 variants in IBD susceptibility and reinforce the role of the innate immune system in IBD pathogenesis.

Adaptor Proteins, Signal Transducing↗
PubMed2005

A common CTLA4 haplotype associated with coeliac disease.

Coeliac disease is a common enteropathy with a strong inherited risk characterised by dietary wheat, rye and barley induced T-cell activation. Although there is replicated linkage to 2q33, results are inconsistent from association studies of the most promising candidate genes: the CD28/CTLA4/ICOS cluster. CTLA4 plays a key role in regulating T lymphocyte mediated inflammatory responses, and variants in the 3' region influence development of diabetes and thyroid disease. We genotyped CTLA4 variants (-1722 C/T, -658 T/C, -318 C/T, +49 A/G, +1822 C/T, CT60 A/G) to tag all common haplotypes (>5% frequency) and an ICOS variant (IVS+173 C/T) in 340 white UK Caucasian coeliac disease cases. Strict ascertainment criteria for coeliac cases required both villous atrophy at diagnosis and positive serology. In total, 973 healthy controls were available for SNP, and 705 for CTLA4 haplotype, based association analyses. Coeliac disease showed weak association with the CTLA4 +1822T (P=0.019) and CT60 G (P=0.047) alleles. Strong association was seen with a common CTLA4 haplotype (P=0.00067, odds ratio 1.41) of frequency 32.7% in coeliac disease and 25.5% in healthy controls. A common CTLA4 haplotype shows strong association with coeliac disease, and contains multiple alleles reported to affect immunological function. Loss of tolerance to dietary antigens in coeliac disease may be mediated in part by heritable variants in co-signalling genes regulating T-cell responses.

Antigens, CD↗
PubMed2005

NOD2, not yet: con.

Explore the source record for details and available documents.

Colitis, Ulcerative↗
PubMed2003

The IBD6 Crohn's disease locus demonstrates complex interactions with CARD15 and IBD5 disease-associated variants.

Genetic studies in inflammatory bowel disease have identified multiple susceptibility loci, whose relevance depends critically on verification in independent cohorts. Genetic variants associated with Crohn's disease have now been identified on chromosomes 5 (IBD5/5q31 risk haplotype) and 16 (IBD1 locus, CARD15/NOD2 mutations). Stratification of genome-wide linkage analyses by disease associated variants is now possible, offering both increased power for identification of other loci and improved understanding of genetic mechanisms. We performed a genome-wide scan of 137 Crohn's disease affected relative pairs from 112 families. Multipoint non-parametric linkage analyses were performed, with further stratification of affection status by common CARD15 mutations and the IBD5 haplotype. We verified linkage of Crohn's disease to regions on chromosome 3 (P=0.0009) and X (P=0.001) in our cohort. Linkage to chromosome 16 (IBD1) was observed in Crohn's disease pairs not possessing common CARD15 mutations (P=0.0007), approximately 25 cM q telomeric of CARD15. Evidence for linkage to chromosome 19 (IBD6) was observed in Crohn's disease pairs not possessing CARD15 mutations (P=0.0001), and in pairs possessing one or two copies of the IBD5 risk haplotype (P=0.0005), with significant evidence for genetic heterogeneity and epistasis, respectively. These analyses demonstrate the complex genetic basis to Crohn's disease, and show that the discovery of disease-causing variants may be used to aid identification of further susceptibility loci in complex disease.

Chromosomes, Human, Pair 16↗
PubMed2003

Thiopurine therapy: when to start and when to stop.

The thiopurines azathioprine and 6-mercaptopurine are effective both for active disease and for maintaining remission in both Crohn's disease and ulcerative colitis. This review describes criteria for starting thiopurines (two or more courses of steroids in a calendar year, relapse as prednisolone is reduced below 15 mg/day, within 6 weeks of stopping steroids) and the benefits of continuing treatment for up to 5 years. Challenging issues, such as thiopurine intolerance, relative merits of azathioprine, 6-mercaptopurine, monitoring therapy and thiopurines in pregnancy are addressed.

Azathioprine↗
PubMed2002

Fine mapping of the IBD1 locus did not identify Crohn disease-associated NOD2 variants: implications for complex disease genetics.

Crohn disease (CD) is a chronic relapsing inflammatory condition of the gastrointestinal tract. Recently, polymorphisms in NOD2 (CARD15), a gene mapping to the chromosome 16 IBD1 susceptibility locus, have been associated with susceptibility to CD. One group identified the gene by using classic positional cloning methods. Here, we report linkage and fine mapping analyses using 27 microsatellite markers encompassing the IBD1 susceptibility locus in 131 CD affected sibling pairs, and a simplex family cohort. No evidence for linkage was observed, and microsatellite markers close to NOD2 did not show association. However, significant association was confirmed in 294 CD trios for the NOD2 variants Arg702Trp and Leu1007fsinsC. Our fine mapping study of the IBD1 locus did not enable us to identify NOD2 as a CD gene, despite the presence of association with disease-causing alleles. This study illustrates the difficulties facing microsatellite linkage and linkage disequilibrium mapping methods for identifying disease genes in complex traits.

Carrier Proteins↗
PubMed2002

Role of NOD2 variants in spondylarthritis.

OBJECTIVE: To investigate the role of the gene NOD2 in susceptibility to, and clinical manifestations of, ankylosing spondylitis (AS). METHODS: A case-control study of NOD2 polymorphisms known to be associated with Crohn's disease (CD) (Pro(268)Ser, Arg(702)Trp, Gly(908)Arg, and Leu(1007)fsinsC) was performed in 229 cases of primary AS with no diagnosed inflammatory bowel disease (IBD), 197 cases of AS associated with IBD (referred to as colitic spondylarthritis; comprising 78 with CD and 119 with ulcerative colitis [UC]), and 229 ethnically matched, healthy controls. Associations between NOD2 polymorphisms and several clinical features of AS, including disease severity assessed by questionnaire and age at spondylarthritis onset, were also investigated. Exclusion linkage mapping of chromosome 16 was performed in a separate group of 185 multicase families with AS. RESULTS: An association was identified between Gly(908)Arg and UC spondylarthritis (P = 0.016, odds ratio [OR] 4.6, 95% confidence interval [95% CI] 1.3-16), and a nonsignificant trend with a similar magnitude was observed in association with CD spondylarthritis (P = 0.08, OR 3.9, 95% CI 0.8-18). The Pro(268)Ser variant was inversely associated with UC spondylarthritis (P = 0.003, OR 0.55, 95% CI 0.37-0.82), but not with CD spondylarthritis. No association was demonstrated between NOD2 variants and primary AS, or between other variants of NOD2 and either UC or CD spondylarthritis. Carriage of the Pro(268)Ser polymorphism was associated with greater disease activity as measured by the Bath Ankylosing Spondylitis Disease Activity Index (P = 0.002). Although patients with CD had a younger age at spondylarthritis onset than did those with UC (22.4 years versus 26.4 years; P = 0.01), no association was noted between the NOD2 variants linked with CD and age at spondylarthritis onset. In primary AS, the presence of a gene with a magnitude of association >2.0 was excluded (exclusion logarithm of odds score less than -2.0), and no association was observed with the microsatellite D16S3136. CONCLUSION: NOD2 variants do not significantly affect the risk of developing primary AS, but may influence susceptibility to, and clinical manifestations of, colitic spondylarthritis.

Adult↗
PubMedDate not supplied

Muramyl dipeptide and toll-like receptor sensitivity in NOD2-associated Crohn's disease.

Both NOD2 (CARD15) alleles are mutated in roughly 15% of patients with Crohn's disease, but functional effects are unclear. We analysed the cytokine response of peripheral blood mononuclear cells to muramyl dipeptide (MDP), the ligand for NOD2. MDP induced little TNFalpha or interleukin 1beta, but strong interleukin-8 secretion. MDP also substantially upregulated secretion of TNFalpha and interleukin 1beta induced by toll-like receptor ligands. These effects were abolished by the most common Crohn's NOD2 double mutant genotypes at low nanomolar MDP concentrations, and provide the basis to develop a test of NOD2 functional deficiency. In Crohn's disease, there are defects in neutrophil recruitment driven by NOD2 and interleukin 8 and in cross talk between the NOD2 and toll-like receptor pathways, which suggests that the immune system fails to receive an early priming signal.

Acetylmuramyl-Alanyl-Isoglutamine↗