P077 Group 1 innate lymphoid cells in creeping fat of Crohn’s disease
Mori, R.(1)*;Ogino, T.(1,2);Sekido, Y.(1);Hata, T.(1);Hamabe, A.(1);Takahashi, H.(1);Miyoshi, N.(1);Uemura, M.(1);Mizushima, T.(1,2,3);Doki, Y.(1);Eguchi, H.(1);
(1)Osaka University, Department of Gastroenterological Surgery- Graduate School of Medicine, Suita- Osaka, Japan;(2)Osaka University, Department of Therapeutics for Inflammatory Bowel Diseases- Graduate School of Medicine, Suita- Osaka, Japan;(3)Osaka Police Hospital, Department of Gastroenterological Surgery, Osaka, Japan;
About half of patients with Crohn’s Disease (CD) require surgery in the course of treatment, furthermore, reoperation for later recurrence is also performed in high frequency. One of the characteristic findings for CD patients is creeping fat (CF) wrapped around inflamed areas of the intestine, and CF correlates with stenosis of the intestinal tract resulting from changes in the connective tissue of the intestinal wall. Lower postoperative recurrences have been reported among CD patients who underwent extensive CF resection, suggesting that CF would be clinically important. However, the detail mechanisms are still unknown. The aim of this study is to examine the functional mechanism and clinical significance of CF focused on innate lymphoid cells (ILCs) and macrophages.
Normal mesentery (NM) of ileum was obtained from microscopically and macroscopically intact areas in patients with colorectal cancer. Mesentery was also obtained from surgically resected specimens from patients with CD who were diagnosed based on established clinical, radiologic, and endoscopic criteria. Mesenteric stromal vascular fraction were isolated by enzymatic digestion. Mesentery from CD patients divided CF and areas with no or slight inflammation (non-CF). Early recurrence was defined as Rutgeerts score (≥2) or worsening of clinical symptoms (CDAI≥220).
RNA-seq of CF revealed that expression of immune-related genes and of fibrosis-related genes were elevated compared with NM and non-CF. Both frequency and numbers of ILC1 were increased, and those of ILC2 and ILC3 were decreased in CF compared with NM. Positive associations between ILC1 and inflammatory macrophages (CD14+ CD163low) related to fat fibrosis were observed in frequency and number per unit weight. FACS and RT-PCR showed ILC1 from CF had higher expression of IFNγ than those from non-CF. Co-culture experiment of ILC1 from CF and SVF from NM showed increased expression of fibrosis associated genes (COL1A, COL3A), inflammatory markers of macrophages (iNOS, Mincle), and TGFB1, and these effects were cancelled by IFNγ-neutralizing antibody. Evaluation of risk factors of early recurrence showed high frequency of ILC1 from CF and low preoperative serum albumin level were significantly associated with early recurrence (P = 0.004, P = 0.04, each). There was a significant difference between the ILC1 high (≥ 80 %) and ILC1 low (< 80 %) from CF in terms of early recurrence-free survival (P = 0.02).
In CF, ILC1 plays a certain role in macrophage function related to fat fibrosis via IFNγ production. CD patients with high ILC1 (≥80%) in the CF have tendency of early recurrence.