A Preliminary Study of Frequency and Clinical Relevance of Cytotoxic Peripheral CD4 and CD8 T Cells in Patients with Anti-MDA5 Positive Dermatomyositis

Abstract

Objectives: Anti-melanoma differentiation-associated gene 5-positive dermatomyositis (MDA5⁺DM) is an autoimmune disease frequently accompanied by rapidly progressive interstitial lung disease (RP-ILD) with high mortality. T cells are implicated in the pathogenesis of MDA5⁺DM and this study aims to measure the frequency and clinical relevance of cytotoxic CD4 and CD8 T cells in this disease.

Methods: T cells expressing Perforin, Granzyme B (GZMB) and Granzyme K (GZMK) were analyzed by flow cytometry from peripheral blood of 19 patients with active MDA5⁺DM and 19 age- and sex-matched healthy donors (HDs). The frequency of CD4 and CD8 T cells and the cytotoxic subsets were compared between patients with MDA5⁺DM and HDs. Correlations within T cell subsets and between T cell subsets and clinical parameters of lactate dehydrogenase (LDH), ferritin, neutrophil-to-lymphocyte ratio (NLR), and Myositis Intention-to-Treat Index (MITAX) were evaluated.

Results: Compared with HDs, patients with active MDA5⁺DM significantly had increased frequency of CD4 T cells, and reduced frequency of GZMK⁺GZMB^- CD8 T cells. Furthermore, the frequency of GZMK⁺GZMB^- CD8 T cells positively correlated with serum ferritin levels in active MDA5⁺DM patients. Notably, the patients in the Dead group of MDA5⁺DM had a significant higher frequency of GZMK⁺GZMB^- CD4 and CD8 T cells.

Conclusion: Substantial changes of cytotoxic T cell subsets are observed in active MDA5⁺DM patients. In addition, a high frequency of GZMK⁺GZMB^- CD4 and CD8 T cells is associated with unfavorable prognosis in MDA5⁺DM. More studies are warranted to further explore the roles of cytotoxic T cells in MDA5⁺DM.

Keywords: anti-melanoma differentiation-associated gene 5-positive dermatomyositis; cytotoxic T cells; granzyme; prognosis.

Figure 1

Gating strategy for flow cytometry analysis of peripheral cytotoxic CD4 and CD8 T cell subsets from HDs and MDA5⁺DM patients. DM, dermatomyositis; HDs, healthy donors; MDA5, melanoma differentiation-associated gene 5.

Figure 2

Comparison of the frequency of CD4 and CD8 T cells between HD and MDA5⁺DM groups. Statistical difference between HD and MDA5⁺DM groups was analyzed using Mann–Whitney test. ^*P < 0.05. DM, dermatomyositis; HD, healthy donor; MDA5, melanoma differentiation-associated gene 5; ns: not significant.

Figure 3

Comparison of the frequency of cytotoxic CD4 and CD8 T cell subsets between HD and MDA5⁺DM groups. The frequency of Perforin⁺, GZMK⁺GZMB⁻, GZMK⁺GZMB⁺, and GZMK⁻GZMB⁺ CD4 T cells (A) or CD8 T cells (B) was compared between HD (n = 19) and MDA5⁺DM (n = 19) groups. Statistical difference between the two groups was analyzed using Mann–Whitney test. (C and D) Heatmaps showing the correlations among cytotoxic CD4 and CD8 T cell subsets from MDA5⁺DM patients (C) and HDs (D). The numbers inside the heatmaps denote correlation coefficients. Spearman correlation analysis was applied. ^*P < 0.05; ^**P < 0.01. DM, dermatomyositis; GZMB, Granzyme B; GZMK, Granzyme K; HDs, healthy donors; MDA5, melanoma differentiation-associated gene 5; ns: not significant.

Figure 4

Association of cytotoxic CD4 and CD8 T cell subsets with clinical parameters in MDA5⁺DM patients. (A) Correlation analysis between serum ferritin levels and the frequency of GZMK⁺DM patients (n = 19). Pearson correlation analysis was applied. (B) Comparison of the frequency of cytotoxic CD4 and CD8 T cells between the Alive (n = 14) and Dead (n = 5) groups in MDA5⁺DM patients (n = 19). Statistical difference between the two groups was analyzed using Student's t test. ^*P < 0.05. DM, dermatomyositis; GZMB, Granzyme B; GZMK, Granzyme K; MDA5, melanoma differentiation-associated gene 5; ns: not significant.