BACKGROUND: Crohn's disease (CD) is an inflammatory bowel disease (IBD) and has been associated with Mycobacterium avium subspecies paratuberculosis (MAP). MAP has been detected in stool, tissue and blood samples from patients with CD. Gamma interferon (γ-IFN) is an inflammatory cytokine that plays a crucial role in killing intracellular pathogens like MAP, and its receptor (IFNGR1) mutations cause immunodeficiency and severe disseminated mycobacterial infections. The role of MAP in association with IFNGR1 mutation in CD patients have not been investigated. METHODS: In this study, we investigated blood samples of 79 human subjects for MAP infection in association with IFNGR1 gene dysfunction. Samples were divided into 22 CD, 6 Ulcerative colitis (UC), 32 normal healthy and 19 non-inflammatory bowel disease (NIBD). Five variants of IFNGR1 single nucleotide polymorphisms (SNP) were investigated using Taqman Genotyping assay, then IFNGR1 expression measured by RT-PCR and serum IFNGR1 and γ-IFN levels were measured using ELISA. MAP infection was detected using nested PCR. RESULTS: Among 28 IBD patients, 4/6 (66.67%) of UC and 18/22 (81.82%) of CD are tested positive for at least one SNP homozygous minor form compared to 21.88% and 47.37%% in 32 healthy and 19 NIBD (P < 0.05). IFNGR1 gene expression was downregulated 1.4-fold in IBD patients (P =0.07) and 1.7-fold downregulated in MAP positive IBD patients compared to MAP negative IBD patients (P=0.06). Serum IFNGR1 protein levels were downregulated 1.53-fold in IBD patients compared to normal, and 1.4-fold downregulated in MAP positive IBD patients compared to MAP negative IBD patients. MAP infection is more common in rs2234711 SNP positive patients (5/7 =71.42%) (P < 0.05). Serum γ-IFN levels were not elevated in both groups. CONCLUSION: IFNGR1 SNP's, MAP infection and IFNGR1 downregulation were found in higher incidence in IBD, suggesting role of IFNGR1 in susceptibility of MAP infection in IBD patients.
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Master of Science (M.S.)
College of Medicine
Length of Campus-only Access
Masters Thesis (Open Access)
Htun, Zin Mar, "Downregulation in IFNGR1 Increases Suspectiblity to Mycobacterium Avium Subspecies Paratuberculosis Infection in Crohn's Disease" (2017). Electronic Theses and Dissertations. 5919.
Restricted to the UCF community until 2-15-2019; it will then be open access.