Introduction

We have previously described the conserved butryophilin-like (BTNL)-γδ axis in health, whereby human intestinal Vγ4 intraepithelial lymphocytes (IEL) are regulated by local, epithelial-restricted proteins BTNL 3/8¹. Mice lacking key Btnls have demonstrable absence of mature Vγ7 IEL, suggesting a T cell selection and maintenance function of these proteins². Furthermore it has previously been described that the BTNL gd axis is dysregulated in coeliac disease³. However this axis and its potential dysregulation has yet to be elucidated in IBD.

Aims & Methods

We aim to compare the status of BTNL dependent γδ T cells in IBD and in healthy tissue, and to assess the potential impact of the BTNL-γδ IEL axis on IBD incidence and progression.
Biopsies obtained at endoscopy from non-IBD controls and patients with IBD with and without inflammation were analysed by flow cytometry and RNA sequencing. We then undertook a large-scale case control study investigating whether there was an association between IBD and a previously described BTNL variant allele. These studies were performed in a test set and findings were replicated and validated using the UK IBD bioresource.

Results

RNA sequencing of colonic γδ cells demonstrated that a subset expressing the integrin α_Εβ7 (CD103) have an intraepithelial transcriptomic programme. Moreover, CD103 expression was reversibly downregulated in gut inflammation. Complete restoration of γδ CD103 expression in IBD patients on treatment (n=7) was associated with significantly lower relapse over 5 years follow up than those who demonstrated an ongoing γδ CD103 dysregulation despite therapy (n=12) (HR 6.54 (1.86 – 22.9) p=0.027). Conventional CD8 T cells also express CD103 which is downregulated by inflammation, but restoration of CD8 CD103 phenotype was not associated with sustained remission (HR 0.72 (0.2 to 2.5) ns).
It was noted that a number of patients and non-IBD controls demonstrated low levels of Vγ4 cells. We investigated whether there may be genetic factors which disrupt communication between Vγ4 IEL and the BTNL3/8 complex. A common 56kb copy number variant (CNV) has previously been described (minor allele frequency 0.310)⁴, and we showed that this polymorphism is hypomorphic in that it disrupts Vγ4-BTNL3 interactions. By phenotyping our local cohort we found that homozygous carriage of this CNV leads to lower proportions of Vγ4 IEL, and those Vγ4 IEL which remain demonstrated an altered phenotype.
To investigate the effects of this on IBD we performed a large case-control study. While there was no association between this CNV and the development of IBD, there was a significant association between the CNV and the development of penetrating Crohn’s disease (CD) in a test set (n=1817), which was subsequently replicated in an independent cohort from the UK NIHR IBD bioresource (n=4491) (OR 1.38 (1.13-1.68) p=0.0015).

Conclusion

This multi-faceted study demonstrates that γδ IEL are an hitherto undescribed marker of inflammation resolution in IBD and may be a useful biomarker of treatment response and restoration of a functioning epithelium. Furthermore, our genetics data clearly implicate the BTNL-Vγ4 axis in regulating CD severity. Only a few genes are associated with IBD prognosis, and for most, the biological pathway involved remains uncertain. By contrast, our study strongly implicates Vγ4 IEL as regulators of IBD pathobiology, possibly by driving wound healing and tissue repair, as has been implied by murine studies. Practical diagnostic and therapeutic applications of this protective pathway should be further investigated.

References

1. Melandri et al Nature Immunology 2018; 19: 1352-1365
2. Di Marco Barros et al Cell 2016; 167: 203-218
3. Mayassi et al Cell 2019; 176: 967-981
4. Aigner et al BMC genetics 2013; 14: 61
   

Disclosure

R.J.D., I.Z., P.V., N.J.P. and A.C.H. have filed provisional patent applications for work described herein. R.J.D. has received speaking/consulting fees from Janssen, Takeda, Tillotts. All unrelated to this manuscript., C.A.L. declares research support and/or fees for development and delivery of non-promotional education from Janssen, Dr Falk, Takeda, Abbvie, AstraZeneca, Eli Lilly, Orion, Pfizer, Roche, Sanofi Aventis, Ferring, UCB, Biogen and Genentech Inc. All unrelated to this manuscript. P.M.I. declares research support and/or fees for development and delivery of non-promotional education from AbbVie, Arena, Boehringer-Ingelheim, BMS, Celgene, Celltrion, Falk Pharma, Ferring, Genentech, Galapagos, Gilead, Hospira, MSD, Janssen, Lilly, Pfizer, Pharmacosmos, Prometheus, Roche, Sandoz, Samsung Bioepis, Takeda, Tillotts, Topivert, Sapphire Medical, Shire, VH2, Vifor Pharma, Warner Chilcott. A.C.H. is a scientific consultant for Prokarium and eGenesis and receives research funds from Takeda Pharmeceuticals. All other authors report no conflict of interest.

Introduction

The International Microbiota Observatory aimed to measure awareness, knowledge and behaviors about the microbiome in general populations worldwide and in patients.

Aims & Methods

The survey was conducted among 7,500 individuals aged 18 years old and over in 11 countries (France, Spain, Portugal, Poland, Finland, Morocco, United States of America, Brazil, Mexico, China and Vietnam). Automated selection from the Ipsos online Panel ensured representative samples of general population fit the quotas method based on gender, age, employment status, and country regions. Participants were asked to fill out an online questionnaire with single- or multiple-choice questions. Demographics, microbiome awareness and knowledge, behaviors, information provided by healthcare professionals were documented and analyzed using descriptive statistics. Our focus is a self-reported patients’ sub-population that included 4,509 individuals with respiratory (n=888), cardiovascular (n=1,177), digestive (n=1,036), genitourinary and kidney (n=529), neurological (315), autoimmune (n=716), osteoarticular (n=1040), psychiatric diseases (n=652), diabetes (n=745), cancer (n=270) and allergies (n=2,097).

Results

4,509 people with various chronic diseases from 11 countries completed the questionnaire (52% female, mean 47,7 years). 70% of these patients have heard of the term “microbiome”, with 24% knowing exactly what it is. However, patients' awareness varies according to the disease they have: people with diabetes are less aware (65%; (p<0.001) and people with digestive diseases are more aware (79%; (p<0.001) of this term compared to all patients. For patients with cardiovascular disease, awareness is not statistically different compared to all patients (68%). In their daily lives, 61% of patients have changed their behaviors to keep their microbiome as balanced and functional as possible. This proportion varies according to the disease they have: patients with cardiovascular diseases are less likely to change their behaviors (57%; p=0.001) while patients with digestive diseases are more likely to change them (73%; p<0.001). And among patients with diabetes, the proportion who have changed their behaviors (59%) is not statistically different compared to all patients. Only 48% of patients had received from a healthcare professional an explanation of what a microbiome is, its role and function. But, compared to all the patients, people with cardiovascular disease (43%; p<0.001) were the patients the least likely to have received this piece of information and those with digestive diseases were more likely to have received it (61%, p<0.001). Finally, 78% of patients would trust healthcare professionals as the first source of relevant and trustworthy information.

Conclusion

This survey provides insights into the need for additional education in patients. Healthcare professionals could play a crucial role in providing information about the role and functions of the microbiome, more precisely tailored to each chronic disease that patients suffer from.

References

https://www.biocodexmicrobiotainstitute.com/en/international-microbiota-observatory

Disclosure

The survey was sponsored by the Biocodex Microbiota Institute.

Introduction

Mirikizumab, a monoclonal antibody targeting the p19 subunit of IL-23, was approved in Germany in May 2024 for the treatment of moderately to severely active ulcerative colitis (UC), following favorable results in clinical trials (1,2). We aimed to evaluate the effectiveness and safety of mirikizumab (MIRI) in a real-world setting, focusing on a population of patients with prior exposure to three or more advanced therapies.

Aims & Methods

​​​​​In October 2023, we initiated a prospective observational study, collecting clinical, biochemical, and endoscopic data from adult patients (n > 100) with moderate to severe UC who began MIRI treatment in our tertiary referral center in Munich, Germany. The primary endpoints were clinical remission, defined as a Clinical Activity Index (CAI, Lichtiger score) <4 and endoscopic remission, defined as an endoscopic Mayo score ≤1 at 12 months. Secondary outcomes included monthly (1-4 mo) and bimonthly (6-12 mo) trends in fecal calprotectin levels, CAI scores, urgency numeric rating scale (NRS), frequency of re-induction therapy (300 mg every 4 weeks for 3 doses), and steroid discontinuation during the observation period. Adverse events were systematically recorded. All statistical analysis was performed by SolidPulse Software in Phyton using pandas, scipy and statsmodels. This report presents the first key results from patients who have completed at least 6 months of treatment.

Results

To date, 73 patients have initiated MIRI therapy as approved; none have discontinued treatment. Of these, 55 patients have reached the 6-month follow-up. These 55 had a median disease duration of 11 years (range 3–43), and 55% were female. All 55 patients had been exposed to three or more advanced therapies before starting MIRI, and 23 patients (42%) received MIRI concomitantly in combination with another targeted therapy. Among the 55 patients, 29 (53%) had previously lost response to ustekinumab (90 mg every 8 weeks), and 19 (35%) were on concomitant corticosteroids at the start of MIRI therapy. At baseline, 36 patients had a Mayo endoscopic score of II or III, and 19 had a score of 0 or I.
Main results:

• The rates of clinical remission (CAI <4) increased from 36% (30/55) at baseline to 42% (23/55) at 1 month (p=0,6), 40% (22/55) at 2 months (p=0,8), 49% (27/55) at 3 months (p=0,09), 58% (32/55) at 4 months (p=0,008), and 58% (32/55) at 6 months (p=0.008, McNemar test).
• Median urgency NRS scores improved from 5 (range 0–10) at baseline to 1 (range 0–9) at 6 months (p<0.0001, two-sided Wilcoxon test).
• Median calprotectin decreased from 460 (range 20–2100) at baseline to 75 (range 20–2100) at 6 months (p<0.0001, two-sided Wilcoxon test).
• Among the 29 patients with prior ustekinumab use, clinical remission increased from 41% (12/29) at baseline to 55% (16/29) at 6 months, though this change did not reach statistical significance (p = 0.3, McNemar test), possibly due to the low number of patients.

Conclusion

Mirikizumab demonstrated clinical effectiveness and was well tolerated in a real-world UC cohort, including patients with longstanding disease and multiple prior treatments with advanced therapies.

References

1) D’Haens G, Dubinsky M, Kobayashi T et al. Mirikizumab as induction and maintenance therapy for ulcerative colitis. NEJM. 2023; 388: 2444–2455.
2) Dubinsky MC, Clemow DB, Hunter Gibble T et al. Clinical effect of mirikizumab treatment on bowel urgency in patients with moderately to severely active ulcerative colitis and the clinical relevance of bowel urgency improvement for disease remission. Crohn's Colitis 360. 2023; 360: 1–13.

Disclosure

This work has been funded by a grant from Eli Lilly

Introduction

Micronutrient deficiency of amino acids display a hitherto underappreciated role in the pathophysiology of IBD. Serine is a nonessential amino acid and directly involved in the cellular redox balance. In the absence of sufficient external supply, serine can be synthesized via glycolysis through the rate-limiting enzyme phosphoglycerate dehydrogenase (PHGDH). Serine metabolism is upregulated in cancer and immune cells, maintaining survival and growth. However, its role in coordinating cellular function in the context of IBD is not known.

Aims & Methods

We hypothesized that serine metabolism provides a novel and underappreciated metabolic switch to maintain immunological homeostasis in the intestinal epithelium of IBD patients.We assessed the gene expression of the rate-limiting enzymes of de novo serine synthesis PHGDH in two cross-sectional IBD cohorts (1. N=67, 2. N=212 patients) and linked PHGDH expression with endoscopic or clinical disease activity. We used murine small intestinal epithelial cells (Mode-K cells) and murine small intestinal and colon organoids to understand the molecular regulator of de novo serine synthesis via PHGDH. To assess the potential role of PHGDH in coordinating innate immune response, Mode-K cells were treated with LPS or tunicamycin in the presence or absence of the Phgdh inhibitor BI-4916. The impact of proinflammatory cytokines Cxcl1 and Il6 was assessed through qPCR and ELISA. Upstream activation of the NFκB signaling pathway was assessed by WB. Seahorse assay was conducted to evaluate the impact of Phgdh on mitochondrial function.

Results

Compared with healthy control, serine metabolic enzyme PHGDH was significantly increased in both UC and CD patients. PHGDH expression correlated with the degree of inflammation in tissue biopsies of IBD patients correlated with ER stress marker (HSP90B1). Chemical induction of ER stress strongly increased the expression of Phgdh, Psat1, and Psph in Mode-K cells and intestinal organoids. To assess the regulatory role of serine metabolism on innate immune function, Mode-K cells were treated in serine/glycine-deprived medium. PHGDH function was inhibited using the specific inhibitor BI-4916. Treatment with tunicamycin or LPS resulted in strong induction of the proinflammatory cytokines Cxcl1 and Il6. Parallel Seahorse assay displayed significantly disrupted mitochondrial function (basal-, ATP linked- and maximum respiration). As serine feeds into the 1C-metabolism to provide mitochondrial-derived formate, we co-treated cells with glycine and formate to overcome the functional consequences of deprived de novo serine synthesis. We show that co-treatment of glycine and formate rescued mitochondrial dysfunction and inhibited Cxcl1 overactivation in intestinal epithelial cells.

Conclusion

Our data provide a novel link on how disrupted serine metabolism directly fuels epithelial-derived proinflammatory mechanisms via disruption of mitochondrial function. Our data suggest a so far underappreciated role of cellular serine metabolism on IBD pathophysiology.