Reparative immunological consequences of stem cell transplantation as a cellular therapy for refractory Crohns disease

Background
Treatment strategies for Crohn’s disease (CD) suppress diverse inflammatory pathways but many patients remain refractory to treatment. Autologous haematopoietic stem cell transplantation (SCT) is an emerging therapy for medically refractory CD though the mechanisms through which it circumvents refractory pathophysiology are unknown.

Objective
The objective of this study is to understand how the immune system reconstitutes post-SCT and whether SCT may function as a cellular therapy restoring appropriately responsive immune cell populations from haematopoietic stem cells (HSCs).

Design
Adults with CD with active clinical and endoscopic disease who failed available medical therapies were enrolled in a phase II study of SCT for refractory CD (n=19). Blood and intestinal samples were collected longitudinally and analysed using CyTOF and scRNA-seq. Stem cell autografts were functionally assayed in mouse xenograft models.

Results
scRNA-seq and CyTOF analyses reveal that SCT predominantly affected the intestinal myeloid lineage with loss of inflammatory populations and return of macrophages capable of supporting mucosal healing. Xenograft models using patient HSCs suggested that HSCs support the early reconstitution of the myeloid lineage and reveal an impairment of short and long-term HSC engraftment that may determine SCT outcomes.

Conclusions
This study suggests SCT functions as a myeloid-directed cellular therapy reinforcing the critical role of macrophages in refractory CD pathophysiology and as a target for cellular therapies. Furthermore, we report an unrecognised functional heterogeneity among HSC subpopulations in CD that may be relevant to our understanding of CD treatment and pathophysiology.

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Cohort profile: the Swedish Inception Cohort in inflammatory bowel disease (SIC-IBD)

Purpose
There is a need for diagnostic and prognostic biosignatures to improve long-term outcomes in inflammatory bowel disease (IBD). Here, we describe the establishment of the Swedish Inception Cohort in IBD (SIC-IBD) and demonstrate its potential for the identification of such signatures.

Participants
Patients aged ≥18 years with gastrointestinal symptoms who were referred to the gastroenterology unit due to suspected IBD at eight Swedish hospitals between November 2011 and March 2021 were eligible for inclusion.

Findings to date
In total, 367 patients with IBD (Crohn’s disease, n=142; ulcerative colitis, n=201; IBD-unclassified, n=24) and 168 symptomatic controls were included. In addition, 59 healthy controls without gastrointestinal symptoms were recruited as a second control group. Biospecimens and clinical data were collected at inclusion and in patients with IBD also during follow-up to 10 years. Levels of faecal calprotectin and high-sensitivity C-reactive protein were higher in patients with IBD compared with symptomatic controls and healthy controls. Preliminary results highlight the potential of serum protein signatures and autoantibodies, as well as results from faecal markers, to differentiate between IBD and symptomatic controls in the cohort. During the first year of follow-up, 37% (53/142) of the patients with Crohn’s disease, 24% (48/201) with ulcerative colitis and 4% (1/24) with IBD-U experienced an aggressive disease course.

Future plans
We have established an inception cohort enabling ongoing initiatives to collect and generate clinical data and multi-omics datasets. The cohort will allow analyses for translation into candidate biosignatures to support clinical decision-making in IBD. Additionally, the data will provide insights into mechanisms of disease pathogenesis.

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Faecal microbiota transplantation in Crohns disease: an Australian randomised placebo-controlled trial protocol

Introduction
The enteric microbiota drives inflammation in Crohn’s disease. Yet, there are no placebo controlled trials evaluating the efficacy and safety of faecal microbiota transplantation (FMT) in inducing and maintaining remission in patients with active Crohn’s disease. The Microbial Restoration (MIRO) study aims to establish this evidence.

Methods and analysis
At two specialist inflammatory bowel disease centres, 120 enrolled patients will have a 3-week period of diet optimisation (removal of ultra-processed foods) together with a 7-day course of antibiotics (to facilitate subsequent FMT engraftment). Patients will then be stratified to upper gut (for disease proximal to the splenic flexure) or lower gut (distal to the splenic flexure) disease. Patients will then be randomised in a 2:1 ratio to receive anaerobically prepared stool or placebo for 8 weeks either by gastroscopy, or colonoscopy and enemas. Clinical response at 8 weeks (Crohn’s Disease Activity Index (CDAI) reduction ≥100 points or to

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