Making sense of the cause of Crohn's - a new look at an old disease

Use of contraceptives and risk of inflammatory bowel disease: a nested case-control study

BACKGROUND

How contraceptive formulation, dose, duration of therapy and mode of delivery affects the risk of inflammatory bowel disease (IBD) is poorly described.

AIM

To examine associations between types of hormonal contraception and development of IBD.

METHODS

This was a nested case-control study using IQVIA Medical Research Data. Women aged 15-49 years with a new diagnosis of IBD were matched with up to six controls by age, practice and year. Odds ratios (OR) and 95% confidence intervals (95% CI) for incident IBD and use of contraception were calculated.

RESULTS

4932 incident cases of IBD were matched to 29 340 controls. Use of combined oral contraceptive pills (COCPs) was associated with the development of Crohn's disease and ulcerative colitis (OR 1.60 [1.41-1.82] and 1.30 [1.15-1.45], respectively). Each additional month of COCP exposure per year of follow-up increased risk of Crohn's disease by 6.4% (5.1%-7.7%) and ulcerative colitis by 3.3% (2.1%-4.4%). Progestogen-only pills had no effect on Crohn's disease risk (OR 1.09 [0.84-1.40]) but there was a modest association with ulcerative colitis (OR 1.35 [1.12-1.64]). Parenteral contraception was not associated with the development of Crohn's disease or ulcerative colitis (OR 1.15 [0.99-1.47] and 1.17 [0.98-1.39], respectively).

CONCLUSIONS

We observed an increase in the risk of IBD with increasing duration of exposure to COCPs. Progestogen-only pills were not associated with Crohn's disease but there was a modest association with ulcerative colitis. There was no association between parenteral progestogen-only contraception and IBD. These findings are broadly consistent with a hypothesis that the oestrogen component of contraception may drive IBD pathogenesis.

Inflammatory bowel disease in Hermansky-Pudlak syndrome: a retrospective single-centre cohort study

BACKGROUND

Knowledge about inflammatory bowel disease (IBD) in patients with Hermansky-Pudlak syndrome (HPS), a rare autosomal recessive disorder characterized by defective biogenesis of lysosome-related organelles, could provide insights into IBD in general.

OBJECTIVE

To expand the understanding of IBD in patients with HPS.

METHODS

Retrospective review of records from patients with HPS evaluated at the National Institutes of Health Clinical Center from 1995 to 2019 was conducted. Clinical features of IBD, genotyping results and histologic findings of colectomy specimens were analysed.

RESULTS

IBD affected 37 (14.2%; 12 male, 25 female) of 261 patients with HPS. Median age of onset was 17 years; range was 1 to 52 years. The most common symptoms of HPS IBD were hematochezia, abdominal pain and loose stools. Fistulae or extra-intestinal manifestations developed in 30% or 22%, respectively. Genotyping showed that patients with biallelic variants in HPS1, HPS3, HPS4 or HPS6 were diagnosed with IBD. Six children had very early-onset IBD. Patients with HPS-3 had mild manifestations of IBD. Medical therapy and bowel resection were utilized to treat 73% and 35% of patients with HPS IBD, respectively; 7 of 13 patients receiving anti-tumor necrosis factor alpha therapy had prolonged clinical responses. Active cryptitis, chronic inflammatory changes, granulomas and ceroid lipofuscinosis were histopathologic findings in three colectomy specimens.

CONCLUSIONS

IBD resembling Crohn's disease affects some patients with HPS; genetic heterogeneity is a feature of HPS IBD. HPS3 is a new gene associated with human IBD. Very early-onset IBD can develop in HPS.

Studies on patients establish Crohn's disease as a manifestation of impaired innate immunity

The fruitless search for the cause of Crohn's disease has been conducted for more than a century. Various theories, including autoimmunity, mycobacterial infection and aberrant response to food and other ingested materials, have been abandoned for lack of robust proof. This review will provide the evidence, obtained from patients with this condition, that the common predisposition to Crohn's is a failure of the acute inflammatory response to tissue damage. This acute inflammation normally attracts large numbers of neutrophil leucocytes which engulf and clear bacteria and autologous debris from the inflamed site. The underlying predisposition in Crohn's disease is unmasked by damage to the bowel mucosa, predominantly through infection, which allows faecal bowel contents access to the vulnerable tissues within. Consequent upon failure of the clearance of these infectious and antigenic intestinal contents, it becomes contained, leading to a chronic granulomatous inflammation, producing cytokine release, local tissue damage and systemic symptoms. Multiple molecular pathologies extending across the whole spectrum of the acute inflammatory and innate immune response lead to the common predisposition in which defective monocyte and macrophage function plays a central role. Family linkage and exome sequencing together with GWAS have identified some of the molecules involved, including receptors, molecules involved in vesicle trafficking, and effector cells. Current therapy is immunosuppressant, which controls the symptoms but accentuates the underlying problem, which can only logically be tackled by correcting the primary lesion/s by gene therapy or genome editing, or through the development of drugs that stimulate innate immunity.