P981 Risankizumab, but not ustekinumab or vedolizumab, downregulates IL-23-induced mucosal pathogenic Th17 cells in patients with Crohn’s disease

Abstract

Abstract Background We recently described an interleukin(IL)-23-inducible pathogenic subset of CCR6+CXCR3-CCR5+ mucosal T helper (Th)17 cells (pTh17) infiltrating Crohn’s disease (CD) inflamed mucosa and specifically activated in response to Adherent-Invasive Escherichia Coli. pTh17 cells are functionally and phenotypically distinct from CCR6+CXCR3-CCR5- Th17 cells (cTh17) and from IL-12-induced CCR6+CXCR3+ Th1/17 subset. Here, we investigated pTh17 cells' recirculation into the bloodstream, localization into the intraepithelial lymphocyte (IEL) compartment, and in-vivo modulation by different biological therapies. Methods Adult patients with active CD initiating either vedolizumab as per clinical practice or ustekinumab and risankizumab during the SEQUENCE trial were prospectively recruited at Fondazione IRCCS Cà Granda, Ospedale Policlinico di Milano. In vedolizumab-treated patients, peripheral blood and intestinal biopsies were collected at baseline and at the end of induction. In ustekinumab- and risankizumab-treated patients, intestinal biopsies were collected outside study protocol assessments at baseline and week 24. Endoscopic response was defined as a greater than 50% decrease in the Simple Endoscopic Score from baseline. Peripheral blood mononuclear cells, lamina propria mononuclear cells (LPMC), and IEL were isolated and analyzed through flow cytometry. Results Overall, 34 CD patients were assessed. Demographic and baseline disease characteristics are summarized in Table 1. At baseline, as compared with cTh17, pTh17 cells: 1. are rarely found in the peripheral blood and express low levels of CCR9 and α4β7, 2. express high levels of tissue-resident markers CD69+CD103+ in the mucosa, and 3. infiltrate the IEL layer upon binding of CD103 with E-cadherin. Baseline pTh17 cells were upregulated in patients not achieving vedolizumab-induced endoscopic response. Upon vedolizumab treatment, a selective downregulation of mucosal cTh17 cells but not pTh17 was observed. Remarkably, risankizumab induced a specific downregulation of pTh17 cells, but not cTh17, in both LPMC and IEL layers. Conversely, ustekinumab reduced Th1/17 mucosal subsets, but not pTh17 cells (Figure 1). Conclusion pTh17 cells are largely unable to recirculate through the bloodstream, express markers of gut-tissue residency, and infiltrate the IEL compartment. IL-23 neutralization by risankizumab specifically downregulates mucosal pTh17 cells, as compared with vedolizumab and ustekinumab. Our immunologic results might provide mechanistic clues to vedolizumab latency effect in CD, and potentially explain early signs of risankizumab superiority over ustekinumab in the SEQUENCE study in terms of endoscopic response at 24 weeks.