IL-15 increases the frequency of effectormemory CD8^(+) T cells in rhesus monkeys immunized with HIV vaccine

Several studies have suggested that interleukin(IL)-15 is a promising adjuvant that promotes cellular immunity when administered with human immunodeficiency virus(HIV)vaccine.Here we evaluated the effect of IL-15 plasmid on HIV-specific immune responses,especially cellular immunity,in eight rhesus monkeys.These monkeys were immunized three times with HIV DNA vaccine with or without IL-15 plasmid and boosted with recombinant Tiantan strain vaccinia virus-based HIV vaccine(rTV)22 weeks after the first immunization.Although we did not detect any significant differences in the HIV-specific CD81 T-cell response between monkeys with IL-15 coimmunization and monkeys with HIV vaccine alone,our results showed that the frequency of effector CD8^(+) memory T cells in the peripheral blood was significantly higher in monkeys with IL-15 coimmunization than those with HIV vaccine alone at almost all of the time points examined.Furthermore,the titers of anti-HIV antibodies were higher in Group T than those in Group C after rTV boosting.These findings in rhesus monkeys suggest that IL-15 may be useful as a cytokine adjuvant for HIV vaccine.

TRAF2 regulates T cell immunity by maintaining a Tpl2-ERK survival signaling axis in effector and memory CD8 T cells

Generation and maintenance of antigen-specific effector and memory T cells are central events in immune responses against infections.We show that TNF receptor-associated factor 2(TRAF2)maintains a survival signaling axis in effector and memory CD8 T cells required for immune responses against infections.This signaling axis involves activation of Tpl2 and its downstream kinase ERK by NF-κB-inducing kinase(NIK)and degradation of the proapoptotic factor Bim.NIK mediates Tpl2 activation by stimulating the phosphorylation and degradation of the Tpl2 inhibitor p105.Interestingly,while NIK is required for Tpl2-ERK signaling under normal conditions,uncontrolled NIK activation due to loss of its negative regulator,TRAF2,causes constitutive degradation of p105 and Tpl2,leading to severe defects in ERK activation and effector/memory CD8 T cell survival.Thus,TRAF2 controls a previously unappreciated signaling axis mediating effector/memory CD8 T cell survival and protective immunity.

Role of Triggering Receptor Expressed on Myeloid Cell-1 Expression in Mammalian Target of Rapamycin Modulation of CD8＋ T-cell Differentiation during the Immune Response to Invasive Pulmonary Aspergillosis

Background： Triggering receptor expressed on myeloid cell- 1 （TREM- 1） may play a vital role in mammalian target ofrapamycin （mTOR） modulation ofCD8＋ T-cell differentiation through the transcription factors T-box expressed in T-cells and eomesodermin during the immune response to invasive pulmonary aspergillosis （IPA）. This study aimed to investigate whether the roTOR signaling pathway modulates the proliferation and differentiation of CD8＋ T-cells during the immune response to I PA and the role TREM-1 plays in this process. Methods： Cyclophosphamide （CTX） was injected intraperitoneally, and Asl？e;gillus.[mnigams spore suspension was inoculated intranasally to establish the immunosuppressed IPA mouse model. After inoculation, rapamycin （2 mg-kg ·d -1） or interleukin （IL）-12 （5 μg/kg every other day） was given for 7 days. The number of CD8＋ effector memory T-cells （Tern）, expression of interferon （IFN）-y, roTOR, and ribosomal protein $6 kinase （S6K）, and the levels of IL-6, IL- 10, galactomannan （GM）, and soluble TREM- 1 （sTREM-I） were measured. Results： Viable A. fumigatus was cultured from the lung tissue of the inoculated mice. Histological examination indicated greater inflammation, hemorrhage, and lung tissue injury in both IPA and CTX ＋ IPA mice groups. The expression of mTOR and S6K was significantly increased in the CTX ＋ IPA ＋ I L- 12 group compared with the control, I PA （P = 0.01 ; P - 0.001 ）, and CTX ＋ 1PA （P = 0.034; P = 0.032） groups, but significantly decreased in the CTX ＋ IPA ＋ RAPA group （P 〈 0.001 ）. Compared with the CTX ＋ IPA group, the proportion of Tern, expression of IFN-y, and the level ofsTREM-I were significantly higher after IL-12 treatment （P = 0.024, P = 0.032, and P = 0.017, respectively）, and the opposite results were observed when the roTOR pathway was blocked by rapamycin （P 〈 0.001）. Compared with the CTX ＋ I PA and CTX ＋ I PA ＋ RAPA groups, IL-12 treatment increased IL-6 and downregulated IL- 10 as well as G M, which strengthened the immune response to the IPA infection. Conclusions： mTOR modulates CD8＋ T-cell differentiation during the immune response to IPA. TREM-1 may play a vital role in signal transduction between mTOR and the downstream immune response.