After being activated by antigen, helper T lymphocytes switch from a resting state to clonal expansion. This switch requires inactivation of the transcription factor Foxo1, a suppressor of proliferation expressed in resting helper T lymphocytes. In the early antigen-dependent phase of expansion, Foxo1 is inactivated by antigen receptor-mediated post-translational modifications. Here we show that in the late phase of expansion, Foxo1 was no longer post-translationally regulated but was inhibited post-transcriptionally by the interleukin 2 (IL-2)-induced microRNA miR-182. Specific inhibition of miR-182 in helper T lymphocytes limited their population expansion in vitro and in vivo. Our results demonstrate a central role for miR-182 in the physiological regulation of IL-2-driven helper T cell-mediated immune responses and open new therapeutic possibilities.

Effector memory T cells are effective in controlling acute infections, but central memory T cells play a key role in long-lasting protection against viruses and tumors. In vivo/in vitro challenge by Ag commonly supports the generation of effector memory T cells with limited longevity. To our knowledge, this study demonstrates for the first time in the human system and under rechallenge conditions that targeting IL-2R by partial mammalian target of rapamycin inhibition or blocking IL-2Rα enriches human CD4+/CD8+ central memory T cells within the virus-specific T cell product associated with enhanced functionality (i.e., multicytokine secretors, including IL-2; enhanced CD137 and CD107a expression on CD8+ and CD4+ T cells, respectively; and killing infected target cells). Remarkably, the effects on CD8+ T cells are mainly mediated via the enhancement of CD4+ T cell function. The data reveal new insights into the role of CD4+ T cell support for the quality of CD8+ T cell memory, even under rechallenge conditions. Moreover, our method offers a new approach to improve the long-lasting efficacy of adoptive T cell therapy in patients.

The immunoregulatory enzyme indoleamine 2,3-dioxygenase (IDO) controls tryptophan metabolism and is induced by pro-inflammatory stimuli. We investigated whether immunostimulatory treatment with granulocyte-macrophage colony-stimulating factor (GM-CSF) influences IDO activity and tryptophan metabolism in sepsis. Thirty-six patients with severe sepsis/septic shock and sepsis-associated immunosuppression (assessed using monocytic human leukocyte antigen-DR (mHLA-DR) expression) were assessed in a controlled trial of GM-CSF or placebo treatment for 8 days. Using tandem mass spectrometry, levels of tryptophan, kynurenine, kynurenic acid, quinolinic acid, 5-hydroxytryptophan, serotonin, and estimated IDO activity were determined in a blinded fashion over a 9-day interval. At baseline, tryptophan and metabolite levels did not differ between the study groups. Although tryptophan levels were unchanged in both groups over the treatment interval (all p>0.8), IDO activity was markedly reduced after GM-CSF treatment (35.4 +/- 21.0 vs 21.6 +/-9.9 (baseline vs day 9), p = 0.02). IDO activity differed significantly between the 2 groups after therapy (p = 0.03). Metabolites downstream of IDO (kynurenine, quinolinic acid, kynurenic acid) were all induced in sepsis and declined in the GM-CSF group, but not in controls. Serotonin pathway metabolites remained unchanged in both groups (all p>0.15). Moreover, IDO activity correlated with procalcitonin (p< 0.0001, r = 0.56) and mHLA-DR levels (p = 0.005, r = -0.28) in the overall samples group. Thus, GM-CSF therapy is associated with decreased IDO activity and reduced kynurenine pathway catabolites in sepsis. This may be due to an improved antibacterial defence.

Human cytomegalovirus infections have a major negative effect on morbidity and mortality of immunosuppressed allograft recipients and indirectly on graft function and survival. The adoptive antiviral T-cell therapy is a novel therapeutic tool to restore immune competence after solid organ transplantation. Till now, the antiviral T-cell products mainly focused on cytotoxic CD8(+) T cells, whereas CD4(+) T cells played a minor role. Here, we demonstrate the importance of CD4(+) T cells within T-cell lines specific for human cytomegalovirus besides its essential support for the quality of CD8(+) T-cell memory. Virus-specific CD4(+) T cells elicit profound functionality after rechallenge (multicytokine secretors, CD137, CD154, and CD107a expression and killing of infected target cells). The CD4(+) T cells show predominantly a Th1 phenotype with cytolytic properties that is mainly perforin-dependent. The data demonstrate the significance of CD4(+) T cells within T-cell products to achieve a successful adoption with enhanced efficacy.

Background. High-mobility group box-1 (HMGB-1) protein is released during “late sepsis” by activated monocytes. We investigated whether systemic HMGB-1 levels are associated with indices of monocytic activation/function in patients with sepsis-induced immunosuppression. Methodology. 36 patients (31 male, 64 ± 14 years) with severe sepsis/septic shock and monocytic deactivation (reduced mHLA-DR expression and TNF-α release) were assessed in a subanalysis of a placebo-controlled immunostimulatory trial using GM-CSF. HMGB-1 levels were assessed over a 9-day treatment interval. Data were compared to standardized biomarkers of monocytic immunity (mHLA-DR expression, TNF-α release). Principle findings. HMGB-1 levels were enhanced in sepsis but did not differ between treatment and placebo groups at baseline (14.6 ± 13.5 versus 12.5 ± 11.5 ng/ml, P = .62). When compared to controls, HMGB-1 level increased transiently in treated patients at day 5 (27.8 ± 21.7 versus 11.0 ± 14.9, P = .01). Between group differences were not noted at any other point of assessment. HMGB-1 levels were not associated with markers of monocytic function or clinical disease severity. Conclusions. GM-CSF treatment for sepsis-induced immunosuppression induces a moderate but only transient increase in systemic HMGB-1 levels. HMGB-1 levels should not be used for monitoring of monocytic function in immunostimulatory trials as they do not adequately portray contemporary changes in monocytic immunity.