Inflammatory activity evaluation in patients with axial spondyloarthritis using MRI relaxometry and mucosal-associated invariant T cells

Abstract

Background: Currently, there is a lack of an objective quantitative measure to comprehensively evaluate the inflammatory activity of axSpA, which poses certain challenges in accurately assessing the disease activity.

Objective: To explore the value of combined-parameter models of sacroiliac joints (SIJs) MRI relaxometry and peripheral blood Mucosal-associated invariant T (MAIT) cells in evaluating the inflammatory activity of axial spondyloarthritis (axSpA).

Methods: This retrospective clinical study included 88 axSpA patients (median age 31.0 (22.0, 41.8) years, 21.6% females) and 20 controls (median age 28.0 (20.5, 49.5) years, 40.0% females). The axSpA group was classified into active subgroup (n=50) and inactive subgroup (n=38) based on ASDAS-CRP. All participants underwent SIJs MRI examination including T1 and T2* mapping, and peripheral blood flow cytometry analysis of MAIT cells (defined as CD3⁺Vα7.2⁺CD161⁺) and their activation markers (CD69). The T1 and T2* values, as were the percentages of MAIT cells and CD69⁺MAIT cells were compared between different groups. Combined-parameter models were established using logistic regression, and ROC curves were employed to evaluate the diagnostic efficacy.

Results: The T1 values of SIJs and %CD69⁺MAIT cells in the axSpA group and its subgroup were higher than the control group (p<0.05), while %MAIT cells were lower than the control group (p<0.05). The T1 values and %CD69⁺MAIT cells correlated positively, while %MAIT cells correlated negatively, with the ASDAS-CRP (r=0.555, 0.524, -0.357, p<0.001). Between the control and axSpA groups, and between the inactive and active subgroups, the combined-parameter model T1 mapping+%CD69⁺MAIT cells has the best efficacy (AUC=0.959, 0.879, sensibility=88.6, 70%, specificity=95.0, 94.7%, respectively).

Conclusion: The combined-parameter model T1 mapping+%CD69⁺MAIT cells allows a more accurate evaluation of the level of inflammatory activity.

Keywords: T1 mapping; axial spondyloarthritis; combined-parameter model; magnetic resonance; mucosal-associated invariant T cells.

Figure 1

T1 and T2* mapping measurements in the sacroiliac joints without or with bone marrow edema (BME). Cases of regions of interest placement in the participant without BME (A) and with BME (B).

Figure 2

Correlations of the ASDAS-CRP with MRI relaxometry values and MAIT cells-related parameters. (A) The correlations of the ASDAS-CRP with T1 values. (B) The correlations of the ASDAS-CRP with T2* values. (C) The correlations of the ASDAS-CRP with %MAIT cells. (D) The correlations of the ASDAS-CRP with %CD69⁺MAIT cells.

Figure 3

(A) Male, 23 years old, HLA-B27: +, CRP:<0.715mg/L, ASDAS-CRP: 0.6, belonged to the inactive group. (B) Female, 30 years old, HLA-B27: +, CRP: 88.3mg/L, ASDAS-CRP: 5.2, belonged to the active group. (A1) The coronal plane of IWI-FS showed no obvious high signal intensity in the subchondral bone of bilateral sacroiliac joints. (A2, A3) Pseudo-color T1 and T2* mapping imaging demonstrates the T1 and T2* value were 653.73 ms and 9.3 ms, respectively. (A4, A5) The percentages of MAIT cells and CD69⁺MAIT cells were 4.6% and 12.3%, respectively. (B1) The coronal plane of IWI-FS showed obvious high signal intensity in the subchondral bone of right sacroiliac joints, and the corresponding articular surfaces are rough. (B2, B3) Pseudo-color T1 and T2* mapping imaging demonstrates the T1 and T2* value were 1317.0 ms and 14.8 ms, respectively. (B4, B5) The percentages of MAIT cells and CD69⁺MAIT cells are 2.3% and 15.2%, respectively.

Figure 4

Receiver operating characteristic curve analysis for single-parameter and combined-parameter models in the diagnosis and inflammation activity assessment of axSpA. (A) Between the control group and axSpA group. (B) Between the inactive group and active group. Model 1:T1 mapping+%MAIT cells; Model 2:T1 mapping +%CD69⁺MAIT cells; Model 3:T1 mpping+%MAIT cells+%CD69⁺MAIT cells.