Date: Sunday, November 5, 2017
Session Type: ACR Poster Session A
Session Time: 9:00AM-11:00AM
Recent animal studies have suggested that γδT-cells accumulate at enthesis, secrete IL-17 and are responsible for driving the spondyloarthritis (SpA) phenotype resulting from IL-23 overexpression in mice (1, 2). In humans examination of the immunological profile of enthesis has been hampered by lack of tissue. Recently, we used a novel strategy to show that group 3 innate lymphoid cells are present at the human enthesis (3). Here we extend our methodology to examine the broader immunological profile of human enthesis and to determine if γδT-cells are also present.
Human etheseal soft tissue (EST) and peri-entheseal bone (PEB) was harvested from normal spinous process in patients undergoing elective spinal orthopaedic procedures. Interspinous EST was dissected from PEB and enzymatically digested, followed by isolation of mononuclear cells. Flow cytometry was then used to determine the proportion of B-cells (CD45+, CD19+) NK cells (CD45+, CD3-, CD56+) and T-cells (CD45+, CD3+). T-cells were then sub divided based on expression of CD4 (T-helper cells), CD8 (Cytotoxic T-cells) and T-cell receptor (TCR) γδ (γδT-cells). For analysis of TCRγδ isoform cDNA was isolated from peripheral blood, EST and PEB and probed with TCRγδ isoform specific oligonucleotides. Entheseal data was compared to age-matched peripheral blood from healthy controls.
Entheseal digests contained on average a lower proportion of T-cells compared to peripheral blood (p=0.018). However, the proportion of T-cells not expressing either CD4 or CD8 was greater in entheseal tissues (p=0.021). As a proportion of T-cells, γδT-cells were 6-fold more numerous in EST compared to peripheral blood (p=0.024), and PEB had 3-fold more. 37% of EST γδT-cells expressed CCR6, this compared to 26% and 34% in PEB and peripheral blood respectively. 46% of EST and 54% PEB entheseal γδT-cells expressed the Vδ1 isoform of the TCR, and clear differences in TCR isoform expression could be observed between peripheral blood, EST and PEB γδT-cell cDNA.
γδT-cells are present in normal human enthesis and constitute a greater proportion of the T-cell pool compared to peripheral blood. A very similar proportion γδT-cells that expressed CCR6, a functional marker for IL-17 production, as was observed as reported in mice (2). Flow cytometry and transcript analysis indicate a high proportion of γδT-cells expressing the Vδ1 isoform of the TCR, which is also associated with homing to the gut and skin. This is the first description of γδT-cells at the human enthesis and offers tentative confirmation of findings in mouse models where these cells play a key role in SpA pathogenesis.
1. Sherlock JP, Joyce-Shaikh B, Turner SP, Chao CC, Sathe M, Grein J, et al. IL-23 induces spondyloarthropathy by acting on ROR-gammat+ CD3+CD4-CD8- entheseal resident T cells. Nat Med. 2012;18(7):1069-76.
2. Reinhardt A, Yevsa T, Worbs T, Lienenklaus S, Sandrock I, Oberdörfer L, et al. IL‐23‐dependent γδ T cells produce IL‐17 and accumulate in enthesis, aortic valve, and ciliary body. Arthritis & Rheumatology. 2016.
3. Cuthbert RJ, Fragkakis EM, Dunsmuir R, Li Z, Coles M, Marzo-Ortega H, et al. Human Enthesis Group 3 Innate Lymphoid Cells. Arthritis Rheumatol. 2017.
To cite this abstract in AMA style:Cuthbert R, Fragkakis EM, Dunsmuir R, Giannoudis P, Jones E, Newton D, McGonagle D. Normal Human Enthesis Contains a Resident Population of γδT-Cells [abstract]. Arthritis Rheumatol. 2017; 69 (suppl 10). https://acrabstracts.org/abstract/normal-human-enthesis-contains-a-resident-population-of-%ce%b3%ce%b4t-cells/. Accessed August 3, 2021.
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