NOD2 Genetic Variants Predispose One of Two Familial Adenomatous Polyposis Siblings to Pouchitis Through Microbiome Dysbiosis.

BACKGROUND AND AIMS: Individuals with familial adenomatous polyposis (FAP) may undergo a total proctocolectomy with ileal pouch-anal anastomosis (IPAA) to surgically treat their disease. Inflammation of the ileal pouch, termed pouchitis, is uncommon in FAP patients but prevalent in patients who received IPAA for ulcerative colitis, a type of inflammatory bowel disease (IBD). METHODS AND RESULTS: We report on two FAP siblings, living in the same household, who underwent IPAA surgery within one week of each other. Their mother also had an IPAA for FAP. One sibling developed pouchitis while his brother and mother have remained pouchitis-free. We investigated the genetic and microbial factors that might explain the development of pouchitis in the one sibling. We surveyed DNA isolated from the two brothers and their parents for NOD2 IBD risk variants by Sanger sequencing. The composition of mucosa-associated bacteria was analyzed by 16S rRNA gene sequencing on terminal ileum and rectal tissue collected at the time of surgical resection from the two brothers. The sibling with pouchitis inherited the IBD-associated risk alleles for NOD2 (rs17221417 and rs2076756) from his healthy father. Both the mother and unaffected brother lacked these variants. Microbiome sequencing of the terminal ileum and rectum found reduced levels of potentially 'beneficial' bacteria (Faecalibacterium prausnitzii, Bacteroides, and Ruminococcaceae) in the sibling with pouchitis relative to his brother. CONCLUSION: These findings suggest that the NOD2 signaling pathway may contribute to intrinsic bacterial dysbiosis which is pre-existing and which may then predispose individuals to pouchitis after IPAA surgery.

Combined Medical and Surgical Approach Improves Healing of Septic Perianal Crohn's Disease.

BACKGROUND: Septic perianal Crohn's disease (SPCD) is a treatment challenge in spite of tumor necrosis factor antagonists (anti-TNF). Our aim was to define the success of SPCD management with a combined medical and surgical approach and to identify clinical and genetic factors predictive of healing. STUDY DESIGN: A retrospective chart review of patients with SPCD treated at the Penn State Milton S Hershey Medical Center was done. Primary end point was complete healing (ie normal clinical exam and no pain for at least 6 months). Genetic analysis of 185 single nucleotide polymorphisms associated with Crohn's disease was performed in 78 patients. RESULTS: One hundred and thirty-five episodes of SPCD were identified in 114 patients with a mean follow-up of 77 ± 7.4 months. Overall, 80 of 135 episodes healed (59.3%) and did not differ between those receiving anti-TNF and not (60.4% vs 56.8%). There appeared to be a consistent improved heal rate in each subcategory of surgically managed patients that received anti-TNF. Female sex was significantly predictive of healing in only those receiving anti-TNF agents (63.6% vs 25.0%; p = 0.0005). Twenty-two (19.3%) patients ultimately received a permanent diversion with either a total proctocolectomy or completion proctectomy. Multivariate analysis suggested several single nucleotide polymorphisms in Crohn's disease-associated genes to be possibly associated with healing, but lost significance after Bonferroni correction. CONCLUSIONS: Overall, there is an approximate 60% rate of healing SPCD using a combined medical and surgical approach. About 20% of SPCD patients will require a permanent stoma. There were no clear genetic predictors of healing SPCD.

Ulcerative colitis neoplasia is not associated with common inflammatory bowel disease single-nucleotide polymorphisms.

BACKGROUND: Neoplasia complicating ulcerative colitis (UC-neoplasia) is a problem that is poorly addressed by present surveillance techniques. The association of greater than 300 single nucleotide polymorphisms (SNPs) with inflammatory bowel disease (IBD) suggests the possibility that certain genetic polymorphisms might identify patients with UC destined for malignant degeneration. This present study tested the hypothesis that presently known IBD-associated SNPs may correlate with UC-neoplasia. MATERIALS AND METHODS: A total of 41 patients with UC-neoplasia (mean age 56 ± 2.1 years) were identified from our divisional IBD Biobank (low-grade dysplasia n = 13, high-grade dysplasia n = 8, colorectal cancer [CRC] n = 20). These patients were individually age, sex, and disease duration matched with UC patients without neoplasia. Primary sclerosing cholangitis and family history of CRC were recorded. Patients were genotyped for 314 of the most commonly IBD-associated SNPs by a custom SNP microarray. Logistic regression and Fischer exact test were used for statistical analysis. RESULTS: After Bonferroni correction, none of the 314 IBD-associated SNPs correlated with UC-neoplasia when compared with matched UC controls. The incidence of primary sclerosing cholangitis was greater in the UC-neoplasia group (10/41, 24% vs 3/41, 7%; P = .03) compared with UC controls. The severity of neoplasia (low grade dysplasia versus high grade dysplasia versus CRC) correlated with disease duration (7.9 vs 13.4 vs 20.7 years, respectively). CONCLUSION: The lack of correlation between well-known IBD-associated SNPs and UC-neoplasia demonstrated in this study suggests that the development of neoplasia in patients with UC is associated with genetic determinants other than those that predispose to inflammation or results from posttranslational modifications or epigenetic factors rather than germline polymorphisms.

The TNFSF15 gene single nucleotide polymorphism rs7848647 is associated with surgical diverticulitis.

OBJECTIVE: To determine if single nuclear polymorphisms (SNPs) in the TFNSF15 gene play a role in patients requiring surgery for diverticulitis. BACKGROUND: A role for a genetic predisposition in diverticulitis is suggested by its association with hereditary connective tissue disorders, youthful onset in some patients, and the observation of families with multiple affected individuals. The TNFSF15 gene has been associated with other inflammatory diseases affecting the colon such as medically refractory ulcerative colitis (UC), aggressive Crohn's disease (CD), and pouchitis after restorative proctocolectomy. METHODS: In the discovery phase of this study, 21 sporadic surgical diverticulitis (SD) patients (9 female, mean age = 52 ± 5) and 5 individuals from a single family with surgically managed diverticulitis [familial diverticulitis (FD), 4 female, mean age = 51.1 ± 7] were studied. SD patients were age and sex matched with 3 separate groups of healthy, CD and UC control patients. All patients were genotyped for 5 known TNFSF15-associated SNPs. The SNP discovered to be associated with diverticulitis (rs7848647) was then confirmed in a separate test group composed of 34 additional patients (20 female, mean age 57.7 ± 2) who also underwent surgical treatment for diverticulitis. These patients were age matched to a new control cohort of patients having no history of diverticulitis (26 female). Patients were genotyped using a TaqMan assay. In the discovery phase, logistical regression on matched subjects was performed to determine an association of TNFSF SNP with diverticulitis versus the control groups. In the test phase, significance for the rs7848647 SNP was assessed by the Fischer's exact test. RESULTS: In the discovery phase, the TNFSF15 SNP rs7848647 was significantly associated with SD (p = 0.0003) versus all control groups studied. The risk allele for this SNP (G substituted for A) was found in all SD patients. The homozygous GG allele was found in 62% (13/21) of SD patients versus only 5% (1/21) of healthy controls (p = 0.001) and 24% (10/42) of all UC + CD controls (p = 0.002). All 5 members of the FD cohort were homozygous for the at-risk "G" allele. In the test group, the homozygous GG genotype was found in 56% of SD patients compared with 17% of healthy controls (p = 0.006). Risk of SD seemed to increase with number of the G alleles with 8% of SD patients having AA homozygosity, 35% of SD patients having AG heterozygosity, and 56% of SD patients having GG homozygosity. CONCLUSIONS: The SNP rs7848647 associated with the TNFSF15 gene is associated with surgical diverticulitis. This finding suggests a fundamental role for TNFSF15, a T-cell receptor gene involved in T-cell maturation, in the pathophysiology of diverticulitis requiring surgery. This SNP may be a marker of diverticular disease severity that might assist in surgical decision making.