Effect of Janus kinase inhibitors on T cell responses to herpes zoster in rheumatoid arthritis patients.

ABSTRACT

OBJECTIVES: The incidence of herpes zoster (HZ) in rheumatoid arthritis (RA) patients is greater than that in healthy controls (HC), particularly in RA patients treated with Janus kinase inhibitors (JAKi). Here, we examined the effect of JAKi on CD4+/CD8+ T cells, cytokine production, and regulation of transcriptional factors in RA patients and HC. METHODS: Peripheral blood mononuclear cells (PBMCs) obtained from RA patients (n=14) and HCs (n=7) were stimulated with varicella zoster virus lysates and exposed to three JAKi inhibitors (ruxolitinib [JAK1/2 inhibitor]; AG490 [JAK2 inhibitor]; and WHI-P154 [JAK3 inhibitor]) in the presence/absence of methotrexate. The CD4+ and CD8+ T cell populations were measured by flow cytometry. Cytokine levels in culture medium were measured by ELISA. Transcription factor expression was examined by RT-qPCR. RESULTS: There was a reduction in the CD4+IFN-γ+, CD4+CD69+IFN-γ+, CD8+IFN-γ+, and CD8+CD69+IFN-γ+ populations, and an increase in the CD4+CD25highFoxp3+ cell population, in PBMCs from RA patients and HCs after exposure to the three JAKi. ELISA revealed a reduction in IFN-γ and granzyme B levels in the presence of JAKi. JAKi reduced expression of mRNA encoding STAT1 and T-bet, but increased that of mRNA encoding STAT5 and Foxp3. Methotrexate plus the highest dose of each JAKi did not affect the Th1, cytotoxic T cell, or Treg populations, the levels of IFN-γ and granzyme B, or expression of transcription factors, significantly. CONCLUSIONS: JAKi reduce the Th1/cytotoxic T cell population and increase the Treg population in both RA patients and HC patients.