EARLY LIFE EXPOSURE TO PARENTAL CROHN'S DISEASE IS ASSOCIATED WITH ALTERED GUT MICROBIOME COMPOSITION, IMPAIRED GUT PERMEABILITY, AND INCREASED RISK OF INCIDENT CROHN'S DISEASE

Background: Cancer is a major cause of morbidity and mortality in persons with inflammatory bowel disease (IBD). We evaluated temporal trends and relative risks of intestinal and extra-intestinal cancers among persons with IBD and matched controls.

Methods: Using population-level administrative data housed at IC/ES (Ontario, Canada), we identified persons with IBD (2002-2017) using a validated algorithm, which also identified diagnoses of Crohn's disease (CD) and ulcerative colitis (UC). Each case was age and sex matched to 10 non-IBD controls and all persons were followed to 2020 for the development of cancer, as identified in the Ontario cancer registry. Only the first organ-specific cancer was counted in each analysis, after which an individual was censored. Individuals were excluded in the analyses of colorectal cancers (CRC) if they underwent proctocolectomy before their first IBD contact and censored at the time of proctocolectomy thereafter. Individuals were censored in all analyses when they died or lost provincial health insurance coverage. Annual cancer incidence rates were age- and sex-standardized to the July 2015 Ontario IBD population. Log-transformed standardized incidence rates for each cancer were analyzed using linear regression, with a first-order autoregressive term, to derive the average annual percentage change (AAPC). Quasi-Poisson regression was used to calculate rate ratios between persons with IBD and controls (2017-2020).

Results: Of the 19,984,538 individuals in the Ontario population from 2002 to 2017, we identified 110,919 persons with IBD. Among persons with IBD, the AAPC significantly decreased for colorectal cancers (CRC) but significantly increased for small bowel cancers, non-Hodgkin’s lymphoma, melanoma and cervical cancers (Table 1). Rates of lung, breast and prostate cancers did not change in IBD, but declined significantly in controls. These trends were similar in persons with UC and matched controls (excluding small bowel cancers). Among persons with CD, the AAPC was not significant for any cancer. During 2017-2020, rates of intestinal cancers, lymphomas, biliary tract cancers and lung cancers were significantly higher in persons with IBD than controls, whereas they did not differ for melanoma or for breast, cervical or prostate cancer.

Conclusions: Rates of CRC have declined, whereas rates of small bowel cancers, NHL, melanoma and cervical cancers have risen, over the past 25 years among persons with IBD . Trends for small bowel, lung, breast, cervical and prostate cancer, as well as for NHL, are discrepant from persons without IBD. Rates of intestinal cancers, lymphomas, biliary tract cancers and lung cancers are higher in persons with IBD than those without IBD. These data should be used inform discussions regarding cancer risks between IBD patients and their practitioners.

Background
Previous studies have shown that offspring of Crohn’s disease (CD) patients have a 6-8 fold risk of incident CD than the general population. Also, newborns of women with CD (vs healthy women) have altered stool microbiome composition and elevated fecal calprotectin (FCP). The "peri-natal period" (pregnancy and first year postpartum) is critical for the development and maturation of the gut microbiome as well as immune responses. However, it is unclear if exposure to parental CD diagnosis during the peri-natal period is associated with increased risk of CD. We aimed to investigate whether peri-natal exposure to parental CD (compared to exposure later in life) has an impact on offspring’s gut barrier function, microbiome composition, and the offspring’s risk of incident CD.
Methods
We assessed 1252 healthy offspring (6-35 years of age) of patients with CD who were recruited in the Crohn’s Colitis Canada Genetic, Environmental, Microbial (CCC-GEM) Project, a large prospective cohort study following healthy first-degree relatives (FDR) of CD patients. We classified offspring into "peri-natally exposed" or "exposed later in life" to parental CD diagnosis. We measured baseline FCP and urinary fractional excretion ratio of lactulose to mannitol (marker of intestinal permeability, LMR). Fecal microbiome composition was determined by 16S rRNA gene sequencing. General estimating equation regression, MaAsLin2, and Cox-proportional hazard modeling was used to assess if peri-natal exposure to parental CD is associated with LMR, FCP, altered microbial composition, and future CD onset. Offspring’s age and sex and family clusters were accounted for in the models.
Results
Offspring exposed to a CD parent peri-natally have a 4.73 fold higher risk (adjusted HR 95%CI 1.28-17.46) of developing CD compared to those exposed to a parent who developed CD later in life (11/586 vs 3/666). Baseline LMR was significantly higher in the offspring exposed to parental CD peri-natally (p=0.003) while no significant difference was observed for FCP at recruitment (p=0.94). We identified five bacterial taxa that were significantly increased in the peri-natally exposed group (false discovery rate-adjusted p<0.05). In a subgroup of offspring of mothers with CD, a dose effect between exposure age and risk was seen; the earlier the offspring was exposed to mother’s CD diagnosis peri-natally, the higher the offspring’s risk of CD development; this trend was not seen in offspring of fathers with CD.
Conclusion
Offspring exposed to parental CD peri-natally had a higher risk of developing CD than those exposed to parental CD later in life. Early life exposure to parental CD was associated with higher baseline LMR and altered bacterial taxa. These results suggest that environmental exposure during the critical peri-natal period may determine the offspring’s future risk of developing CD.