The role of the innate and adaptive immune system in pediatric inflammatory bowel disease

ATG16L1 rs2241880/T300A increases susceptibility to perianal Crohn's disease: An updated meta-analysis on inflammatory bowel disease risk and clinical outcomes

BACKGROUND

ATG16L1 plays a fundamental role in the degradative intracellular pathway known as autophagy, being a mediator of inflammation and microbial homeostasis. The variant rs2241880 can diminish these capabilities, potentially contributing to inflammatory bowel disease (IBD) pathogenesis.

OBJECTIVES

To perform an updated meta-analysis on the association between ATG16L1 rs2241880 and IBD susceptibility by exploring the impact of age, ethnicity, and geography. Moreover, to investigate the association between rs2241880 and clinical features.

METHODS

Literature searches up until September 2022 across 7 electronic public databases were performed for all case-control studies on ATG16L1 rs2241880 and IBD. Pooled odds ratios (ORP ) and 95% CI were calculated under the random effects model.

RESULTS

Our analyses included a total of 30,606 IBD patients, comprising 21,270 Crohn's disease (CD) and 9336 ulcerative colitis (UC) patients, and 33,329 controls. ATG16L1 rs2241880 was significantly associated with CD susceptibility, where the A allele was protective (ORP : 0.74, 95% CI: 0.72-0.77, p-value: <0.001), while the G allele was a risk factor (ORP : 1.23, 95% CI: 1.09-1.39, p-value: 0.001), depending on the minor allele frequencies observed in this multi-ancestry study sample. rs2241880 was predominantly relevant in Caucasians from North America and Europe, and in Latin American populations. Importantly, CD patients harbouring the G allele were significantly more predisposed to perianal disease (ORP : 1.21, 95% CI: 1.07-1.38, p-value: 0.003).

CONCLUSIONS

ATG16L1 rs2241880 (G allele) is a consistent risk factor for IBD in Caucasian cohorts and influences clinical outcomes. As its role in non-Caucasian populations remains ambiguous, further studies in under-reported populations are necessary.

Comparison of Disease Phenotype and Course among Elderly- and Early-Onset Inflammatory Bowel Diseases in the Middle East

BACKGROUND

It is unknown if the clinical manifestations and phenotype of disease are comparable between early- and elderly-onset inflammatory bowel disease (IBD). We aimed to seek differences in disease phenotype, course, complications, and treatment between early- and elderly-onset IBD patients.

METHODS

This retrospective cohort study on registered IBD patients in the Iranian Registry of Crohn's and Colitis (IRCC) compared demographics, disease phenotype, disease activity, IBD-related surgery and medications between early- and elderly-onset IBD. A generalized linear regression model was used to investigate the relative risk of age at diagnosis adjusted for gender and disease duration for the outcomes.

RESULTS

From 10048 IBD patients, 749 with early-onset (7.5%), and 472 (4.7%) elderly-onset IBD were enrolled: 855 (63.1%) ulcerative colitis (UC) and 366 (26.9%) Crohn's disease (CD). Left-sided colitis was more frequent among elderly-onset UC patients (P<0.001). Ileum and ileocolonic locations were the most common types in elderly-onset and early-onset CD patients, respectively. In comparison with elderly-onset UC, early-onset cases more often used prednisolone (22.1% vs. 11.4%, P=0.001), immunomodulators (44.9% vs 25.2%, P<0.001) and anti-tumor necrosis factors (TNF) (20.1% vs 11.9%, P=0.002). Elderly-onset UC patients had 0.7 times lower risk of aggressive phenotype (95%CI:0.6‒0.9, P=0.005). Early-onset CD was associated with higher use of prednisolone (27.7% vs 8.1%, P<0.001), immunomodulators (58.7% vs 41.8%, P=0.005) and anti-TNF (49.6% vs 35.4%, P=0.006).

CONCLUSION

Early-onset IBD was associated with a more aggressive phenotype and higher prednisolone, immunomodulators, and anti-TNF use.

Characteristics of adult patients newly diagnosed with Crohn's disease: interim analysis of the nation-wide inception cohort registry study of patients with Crohn's disease in Japan (iCREST-CD)

BACKGROUND

The Inception Cohort Registry Study of Patients with Crohn's Disease aimed to clarify clinical characteristics and disease course of newly diagnosed Crohn's disease patients in Japan throughout a 4-year period. Results from an interim analysis of the largest nation-wide registry study that covers approximately 1% of Crohn's disease patient population in Japan are reported.

METHODS

This prospective, observational registry study was conducted at 19 tertiary centers in Japan. Patients newly diagnosed with Crohn's disease after June 2016 (age ≥ 16 years at informed consent) were enrolled between December 17, 2018 and June 30, 2020. Patient demographics, diagnostic procedures and categories, disease location and lesion behavior (Montreal classification) at the time of diagnosis were recorded.

RESULTS

Of 673 patients enrolled, 672 (99.9%) were analyzed (458: men, 214: women), male-to-female ratio: 2.1, median age at diagnosis 25 (range 13-86) years; peak age of disease diagnosis: 20-24 years. Most common disease location was L3 (ileocolonic; 60.1%). Non-stricturing, non-penetrating (B1) disease was most common behavior (62.8%); 48.9% reported perianal lesions. Notably, age-wise analysis revealed disease phenotypes varied between patients aged < 40 and ≥ 40 years in terms of male-to-female ratio (2.5/1.3)/disease location (L3: 66.3%/37.0%)/disease behavior (B1: 66.4%/50.0%)/perianal lesion: (55.7%/20.5%) at Crohn's disease diagnosis, respectively.

CONCLUSIONS

Interim analysis of this nation-wide Inception Cohort Registry Study of Patients with Crohn's Disease revealed the demographics and disease characteristics of newly diagnosed Crohn's disease patients in Japan and demonstrated that disease phenotype varied between patients aged < 40 and ≥ 40 years, serving as important information for management of individual patients.

Azathioprine Has a Deleterious Effect on the Bone Health of Mice with DSS-Induced Inflammatory Bowel Disease

Patients with inflammatory bowel disease (IBD) often present poor bone health and are 40% more at risk of bone fracture. Studies have implicated autophagy in IBD pathology and drugs used to treat IBD stimulate autophagy in varying degrees, however, their effect on the skeleton is currently unknown. Here, we have utilised the dextran sulphate sodium (DSS) model of colitis in mice to examine the effects of the thiopurine drug azathioprine on the skeleton. Ten-week-old male mice (n = 6/group) received 3.0% DSS in their drinking water for four days, followed by a 14-day recovery period. Mice were treated with 10 mg/kg/day azathioprine or vehicle control. Histopathological analysis of the colon from DSS mice revealed significant increases in scores for inflammation severity, extent, and crypt damage (p < 0.05). Azathioprine provided partial protection to the colon, as reflected by a lack of significant difference in crypt damage and tissue regeneration with DSS treatment. MicroCT of vehicle-treated DSS mice revealed azathioprine treatment had a significant detrimental effect on the trabecular bone microarchitecture, independent of DSS treatment. Specifically, significant decreases were observed in bone volume/tissue volume (p < 0.01), and trabecular number (p < 0.05), with a concurrent significant increase in trabecular pattern factor (p < 0.01). Immunohistochemical labelling for LC3 revealed azathioprine to induce autophagy in the bone marrow. Together these data suggest that azathioprine treatment may have a deleterious effect on IBD patients who may already be at increased risk of osteoporotic bone fractures and thus will inform on future treatment strategies for patient stratification.

Regulatory role of NKG2D+ NK cells in intestinal lamina propria by secreting double-edged Th1 cytokines in ulcerative colitis

The role of intestinal lamina propria (LP) NKG2D+ NK cells is unclear in regulating Th1/Th2 balance in ulcerative colitis (UC). In this study, we investigated the frequency of LP NKG2D+ NK cells in DSS-induced colitis model and intestinal mucosal samples of UC patients, as well as the secretion of Th1/Th2/Th17 cytokines in NK cell lines after MICA stimulation. The role of Th1 cytokines in UC was validated by bioinformatics analysis. We found that DSS-induced colitis in mice was characterized by a Th2-mediated process. In acute phrase, the frequency of LP NKG2D+ lymphocytes increased significantly and decreased in remission, while the frequency of LP NKG2D+ NK cells decreased significantly in acute phase and increased in remission. No obvious change was found in the frequency of total LP NK cells. Similarly, severe UC patients had a higher expression of mucosal NKG2D and a lower number of NKG2D+ NK cells than mild to moderate UC. In NK cell lines, the MICA stimulation could induce a predominant secretion of Th1 cytokines (TNF, IFN-γ). Furthermore, in bioinformatics analysis, mucosal Th1 cytokine of TNF, showed a double-edged role in UC when compared to the Th1-mediated disease of Crohn's colitis. In conclusion, LP NKG2D+ NK cells partially played a regulatory role in UC through secreting Th1 cytokines to regulate the Th2-predominant Th1/Th2 imbalance, despite of the concomitant pro-inflammatory effects of Th1 cytokines.