Background/Purpose: Although studies have identified the presence of gut-associated cells in the enthesis of joints affected by spondyloarthritis, a direct link through cellular transit between the gut and joint has yet to be formally demonstrated. Using the KikGR transgenic mice to label in situ and track cellular trafficking from the distal colon to the joint under inflammatory conditions of both the gut and joint, we aimed to determine the relative roles of gut-trafficked T cells in the joint.

Methods: KikGR x TNF^DARE/+ mice, which spontaneously develop Crohn’s like intestinal inflammation and spondyloarthritis-like joint inflammation, and KikGR x TNF^+/+ controls underwent colonoscopy-guided photo-labeling of the distal colon epithelium. At 72 hours after photo-labelling, we harvested the popliteal lymph nodes (PLNs) from both KikGR x TNF^DARE/+ and KikGR x TNF^+/+ mice. Following magnetic sorting of T cells by negative selection, T cells were stimulated with anti-CD3 anti-CD28 for 4 hours in the presence of protein transport blockade. T cells then were evaluated by flow cytometry for activation, cytokine production, and transcription factors. To assess the contribution of gut-derived T cells to disease, we reconstituted Rag1^-/- mice with colon epithelium associated T cells from and TNF^DARE/+ and TNF^+/+ donors harvested by negative selection magnetic sorting. After 8 weeks of homeostatic proliferation, we assessed joint inflammation by histology 5 days following injection of complete Freund’s adjuvant (CFA) into the left hind hock.

Results: 72 hours following photo-labeling, gut-trafficked T cells are observed in the Achilles enthesis in equal proportions (~10% of total T cells) between TNF^DARE/+ and TNF^+/+ mice. In the PLNs, photo-labeled T cells expressed markers of terminal differentiation, with 51% of labeled cells Foxp3+ and 19% Roryt+, compared to 10% and 1.7% in the unlabeled fraction, respectively (P< 0.01), similar in both TNF^DARE/+ and TNF^+/+ mice. Ex vivo stimulation of T cells isolated from the PLNs demonstrated significant enrichment of TNF and IL-17A production in the photo-labeled gut-derived T cells compared to unlabeled cells. As expected, gut-derived T cells derived from TNF^DARE/+ animals produced higher levels of TNF compared to littermate controls (45% vs 5%, P=0.1); However, while we observed a large and significant enrichment for Il-17A positivity in greater proportion within gut-derived cells in TNF^+/+ mice (41% vs 1%, P< 0.0001) this enrichment was smaller and not significant in the TNF^DARE/+ (29% vs 5% P =0.2). Transfer of gut-derived T cells into Rag1^-/- mice resulted in moderately increased inflammation in recipients of TNF^+/+ T cells (P=0.056), and a significant increase in inflammation in recipients of TNF^DARE/+ cells (P=0.01), compared to unmanipulated Rag1^-/- mice, when challenged with hock injection of CFA.

Conclusion: Our data demonstrate a direct link between the gut and joint through trafficking of gut-derived T cells with the potential to be directly pathogenic through production of pro-inflammatory cytokines like IL-17 and TNF and exacerbation of joint inflammation. Altogether our data suggest a means by which gut-derived T cells may drive joint pathology.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/cytokine-competent-gut-joint-migratory-t-cells-contribute-to-inflammation-in-the-joint/