Silica particles induce lung inflammation and fibrosis. Here we show that stimulator of interferon genes (STING) is essential for silica-induced lung inflammation. In mice, silica induces lung cell death and self-dsDNA release in the bronchoalveolar space that activates STING pathway. Degradation of extracellular self-dsDNA by DNase I inhibits silica-induced STING activation and the downstream type I IFN response. Patients with silicosis have increased circulating dsDNA and CXCL10 in sputum, and patients with fibrotic interstitial lung disease display STING activation and CXCL10 in the lung. In vitro, while mitochondrial dsDNA is sensed by cGAS-STING in dendritic cells, in macrophages extracellular dsDNA activates STING independent of cGAS after silica exposure. These results reveal an essential function of STING-mediated self-dsDNA sensing after silica exposure, and identify DNase I as a potential therapy for silica-induced lung inflammation.

Live attenuated RNA viruses make highly efficient vaccines. Among them, measles virus (MV) vaccine has been given to a very large number of children and has been shown to be highly efficacious and safe. Therefore, this vaccine might be a very promising vector to immunize children against both measles and other infectious agents, such as human immunodeficiency virus. A vector was previously derived from the Edmonston B strain of MV, a vaccine strain abandoned 25 years ago. Sequence analysis revealed that the genome of this vector diverges from Edmonston B by 10 amino acid substitutions not related to any Edmonston subgroup. Here we describe an infectious cDNA for the Schwarz/Moraten strain, a widely used MV vaccine. This cDNA was constructed from a batch of commercial vaccine. The extremities of the cDNA were engineered in order to maximize virus yield during rescue. A previously described helper cell-based rescue system was adapted by cocultivating transfected cells on primary chicken embryo fibroblasts, the cells used to produce the Schwarz/ Moraten vaccine. After two passages the sequence of the rescued virus was identical to that of the cDNA and of the published Schwarz/Moraten sequence. Two additional transcription units were introduced in the cDNA for cloning foreign genetic material. The immunogenicity of rescued virus was studied in macaques and in mice transgenic for the CD46 MV receptor. Antibody titers and T-cell responses (ELISpot) in animals inoculated with low doses of rescued virus were identical to those obtained with commercial Schwarz MV vaccine. In contrast, the immunogenicity of the previously described Edmonston B strain-derived MV clone was much lower. This new molecular clone will allow for the production of MV vaccine without having to rely on seed stocks. The additional transcription units allow expressing heterologous antigens, thereby providing polyvalent vaccines based on an approved, safe, and efficient MV vaccine strain that is used worldwide.

؉ and CD4 ؉ cells specific for HIV gp120 was also detected in MV-susceptible mice. Furthermore, recombinant MV was able to raise immune responses against HIV in mice and macaques with a preexisting anti-MV immunity. Therefore, recombinant MV vaccines inducing anti-HIV neutralizing antibodies and specific T lymphocytes responses deserve to be tested as a candidate AIDS vaccine.

An inhibitor of the cytotoxic functions (ICF) mediated by human immunodeficiency virus (HIV)- or HLA-specific cytotoxic T lymphocytes, natural killer and lymphokine-activated killer (LAK) cells is secreted by CD8+CD57+ T lymphocytes, a subset expanded during infection with HIV and after bone marrow transplantation. We previously showed an apparent molecular mass of 20-30 kDa for this soluble glycosylated concanavalin A-binding inhibitor which is distinct from known cytokines. Here, we report a characterization of the mechanism of action of this CD8+CD57+ ICF. We show that the ICF-induced inhibition of LAK cell cytolytic activity is transient, with a spontaneous recovery of cytolytic potential after 18 h. When testing interactions of ICF with a large set of cytokines we found that the ICF-mediated inhibition of cytotoxic functions is antagonized by two cytokines: recombinant interleukin (rIL)-4 and recombinant interferon (rIFN)-gamma. Finally, we show that ICF acts at the level of cytolytic effector cells, where it induces a significant increase of cyclic AMP (cAMP) level. In contrast, no modification of either cell surface antigen expression or of target/effector cell conjugate formation could be evidenced. Addition of rIL-4 and rIFN-gamma reverses such an increase of cAMP levels and in parallel restores the cytolytic activity. Altogether, these data demonstrate that the glycoprotein ICF produced by CD8+CD57+ cells (1) inhibits cell-mediated cytotoxicity by sensitizing cytolytic effector cells to the cAMP pathway, and (2) is part of a cytokine network controlling cell-mediated cytotoxic functions.

Major expansions of CD8hi+CD57+ T lymphocytes frequently occur during human immunodeficiency virus (HIV) infection and after transplantation. To investigate mechanisms of such cell expansion, we compared the activation and functional status of CD8hi+CD57+ and CD57-peripheral blood lymphocytes (PBL) from normal, bone marrow transplantation (BMT) and HIV+ donors. The CD8hi+CD57+ PBL from BMT and HIV+ donors preferentially displayed CD38 and HLA-DR activation markers without correlation between CD8hi+CD57+ percentages and HIV load, the CD45RA+ isoform in all ex vivo conditions but acquired CD45RO after in vitro expansion, CD11b and CD11c in BMT and HIV+ donors but decreased expression of CD62-L, VLA-2 and VLA-6. The CD8hi+CD57+ cells were positive for perforin and granzyme B and spontaneously mediated cytolytic activity in a CD3-redirected assay. In contrast the inhibitor of cytolytic functions (ICF) produced by CD8hi+CD57+ cells down-modulated the CD3-redirected cytolytic activity but only at low levels of CD3 cross-linking. While CD3-triggering induced a low, if any, short-term proliferation of CD8+CD57+ cells, this subset could be amplified after long-term stimulation either with mitogens or with HIV antigens, thereby enriched in HIV-specific T cells producing tumor necrosis factor-alpha. Altogether these data suggest that CD8hi+CD57+ cells represent a terminal differentiation state of activated effector cytotoxic T lymphocytes which are enriched in antigen-specific T cells and down-modulate their own cytolytic potential, thus participating in a negative control of effector cell functions during persistent viral infections or transplantations.

The influence of HIV burden variations on the frequencies of Ag-specific CD8+ T cell responses was evaluated before and during highly active antiretroviral therapy by analyzing the number, diversity, and function of these cells. The frequencies of HLA-A2-restricted CD8+ PBL binding HLA-A2/HIV-epitope tetramers or producing IFN-γ were below 1%. A panel of 16 CTL epitopes covering 15 HLA class I molecules in 14 patients allowed us to test 3.8 epitopes/patient and to detect 2.2 ± 1.8 HIV epitope-specific CD8+ subsets per patient with a median frequency of 0.24% (0.11–4.79%). During the first month of treatment, viral load rapidly decreased and frequencies of HIV-specific CD8 PBL tripled, eight new HIV specificities appeared of 11 undetectable at entry, while CMV-specific CD8+ PBL also appeared. With efficient HIV load control, all HIV specificities decayed involving a reduction of the CD8+CD27+CD11ahigh HIV-specific effector subset. Virus rebounds triggered by scheduled drug interruptions or transient therapeutic failures induced four patterns of epitope-specific CD8+ lymphocyte dynamics, i.e., peaks or disappearance of preexisting specificities, emergence of new specificities, or lack of changes. The HIV load rebounds mobilized both effector/memory HIV- and CMV-specific CD8+ lymphocytes. Therefore, frequencies of virus-specific CD8 T cells appear to be positively correlated to HIV production in most cases during highly active antiretroviral therapy, but an inverse correlation can also be observed with rapid virus changes that might involve redistribution, sequestration, or expansion of these Ag-specific CD8 T cells. Future strategies of therapeutic interruptions should take into account these various HIV-specific cell dynamics during HIV rebounds.

No abstract

Leukemic T-LGL (large granular lymphocyte) composed of clonal CD3 + TCR␣␤ + CD8 ؉ CD57 ؉ cells were compared with oligoclonally CD3 ؉ CD8 hi؉ CD57 ؊ lymphocytes expanded after BMT. Leukemic CD3 ؉ CD8 hi؉ CD57 ؉ LGL showed several phenotypic differences such as an upregulation of CD16 and adhesion molecules (mainly CD11c, CD58 and CD54), activation markers and an exclusive CD45RA isoform expression. Unstimulated CD3 ؉ CD8 ؉ CD57 ؉ LGL from both leukemic and BMT donors spontaneously developed an ex vivo CTL-like CD3-redirected cytotoxicity but no NK cell activity. Different stimuli (PHA, PMA or rhIL-2) induced similar cytotoxic profiles after a 6-day culture involving a CD3-redirected lysis predominating over a low NK cell activity. However, culture of leukemic LGL with these stimuli allowed either a 2 week persistence (PMA or rhIL-2) of CD8 ؉ CD57 ؉ LGL or their disappearance after 3 days (PHA). Furthermore, leukemic CD8 hi؉ CD57 ؉ T lymphocytes produced an inhibitor of cytotoxic functions as previously described for BMT recipients' CD8 ؉ CD57 ؉ cells. Thus, despite some phenotypic differences between both cell sources, leukemic CD57 ؉ T-LGL display the same functional characteristics of cytotoxic effector and immunoregulatory T cells as CD8 ؉ CD57 ؉ T cells from BMT recipients which might represent their normal counterpart.