RESUMO
During virus infection, T cells must be adapted to activation and lineage differentiation states via metabolic reprogramming. Whereas effector CD8+ T cells preferentially use glycolysis for their rapid proliferation, memory CD8+ T cells utilize oxidative phosphorylation for their homeostatic maintenance. Particularly, enhanced AMP-activated protein kinase (AMPK) activity promotes the memory T cell response through different pathways. However, the level of AMPK activation required for optimal memory T cell differentiation remains unclear. A new metformin derivative, IM156, formerly known as HL156A, has been reported to ameliorate various types of fibrosis and inhibit in vitro and in vivo tumors by inducing AMPK activation more potently than metformin. Here, we evaluated the in vivo effects of IM156 on antigen-specific CD8+ T cells during their effector and memory differentiation after acute lymphocytic choriomeningitis virus infection. Unexpectedly, our results showed that in vivo treatment of IM156 exacerbated the memory differentiation of virus-specific CD8+ T cells, resulting in an increase in short-lived effector cells but decrease in memory precursor effector cells. Thus, IM156 treatment impaired the function of virus-specific memory CD8+ T cells, indicating that excessive AMPK activation weakens memory T cell differentiation, thereby suppressing recall immune responses. This study suggests that metabolic reprogramming of antigen-specific CD8+ T cells by regulating the AMPK pathway should be carefully performed and managed to improve the efficacy of T cell vaccine.
RESUMO
OBJECTIVE: CD70-expressing CD4 T cells are enriched in RA and promote autoimmunity via co-stimulatory CD70-CD27 interaction. This study aimed to explore the phenotype and cytokine production of CD70(+) CD4 T cells in RA. METHODS: Peripheral blood mononuclear cells from 32 RA patients were isolated and frequencies of CD70(+) cells within different CD4 T subsets were analysed using flow cytometry. IFN-γ and IL-17 production were compared between the CD70(+) and CD70(-) cells. Expression of master transcription factors T-bet, GATA3 and retinoic acid-related orphan receptor gamma t (RORγt) were examined by real-time PCR. Results are presented as mean (s.e.m.). RESULTS: CD4 T cells of healthy controls rarely expressed CD70 as compared with CD4 T cells of RA patients [mean 0.9% (s.e.m. 0.3%) vs 7.6 (0.6), P < 0.001]. In RA, CD70(+) cells were present within all CD4 T cell subsets, i.e. CD45RA(+)CCR7(+) naive, CD45RA(-)CCR7(+) central memory, CD45RA(-)CCR7(-) effector memory and CD45RA(+)CCR7(-) terminally differentiated effector memory T cells with a mean frequency of 3.9% (s.e.m. 1.1%), 4.0 (0.5), 4.2 (0.7) and 9.4 (4.3), respectively. As compared to CD70(-) CD4 T cells, CD70(+) CD4 T cells produced significantly more IFN-γ and IL-17 after short activation. CD70(+) CD4 T cells preferentially expressed transcription factor RORγt. CONCLUSION: CD70(+) CD4 T cells are enriched in RA and may directly contribute to RA pathogenesis by producing IFN-γ and IL-17. Targeting CD70(+) CD4 T cells might offer new therapeutic opportunities in RA.