6 - MATRIX METALLOPROTEINASE MEDIATED CLEAVAGE OF SURFACE PD-L1 ON (MYO)FIBROBLAST CONTRIBUTES TO THE DYSREGULATION OF T-CELL RESPONSES IN CROHN’S DISEASE
(Room Pinyon 3)
18 Jan 18
2:40 PM
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2:55 PM
Tracks:
Clinical and Research Challenges, Lloyd Mayer, MD, Young IBD Investigators Workshop
Introduction: Increased Th1/Th17 immune response is a hallmark of Crohn’s Disease (CD) Immunopathogenesis. CD90+ (myo)fibroblasts (CMF) are an abundant cells in colonic mucosa contributing to the mucosal tolerance via suppression of Th1 cell activity through PD-L1 signaling. CD-CMFs have decreased surface PD-L1, yet the mechanism responsible for this decrease is unknown. Increased expression of Matrix Metalloproteinases (MMPs), has been reported in CD. We hypothesize that increased MMP activity by CD-CMFs reduces cell surface level of PD-L1 contributing to the disruption of CMF-mediated suppression of Th1 type responses. Methods: Real-time RT-PCR, luminex arrays, and flow cytometry were used to determine MMP and PD-L1 expression & secretion in human normal- and CD- mucosa and CMFs. Results: Increase of MMP-1,-7,-9, and -10 was observed within inflamed vs non-inflamed CD-colonic mucosa. When compared to normal (N)-CMFs, CD-CMFs expressed higher basal level of MMP-7 and -10. Stimulation of CD-CMFs with the TLR4 agonist LPS, which is implicated in CD, resulted in higher expression of MMP-7,-9, and -10 mRNA when compared to N-CMF. Treatment of N-CMFs with combinations of recombinant human MMP-7,-9, and-10 resulted in significant decreased cell surface level of PD-L1. By contrast, inhibition of MMP activity with specific inhibitors or neutralizing antibodies increased surface PD-L1 in CD-CMFs. CD-CMFs demonstrate reduced capacity to suppress Th1 (Tbet and IFN-gamma) and Th17 (RORC and IL-17A) activity when co-cultured with CD3/CD28 preactivated CD4+ Tcells, while supplementation of the coculture with MMP specific inhibitors or neutralizing antibodies restored the CD-CMF mediated suppression. Conclusions: Our data suggests that increased MMP expression by CD-CMFs likely to contribute to the increase in Th1/Th17 cells activity through enzymatic cleavage of cell surface PD-LI on CD-CMFs thereby reducing its surface level and negative co-stimulator activity.