Shared and distinct transcriptional programs underlie the hybrid nature of iNKT cells

Invariant natural killer T cells (iNKT cells) are innate-like T lymphocytes that act as critical regulators of the immune response. To better characterize this population, we profiled gene expression in iNKT cells during ontogeny and in peripheral subsets as part of the Immunological Genome Project. High-resolution comparative transcriptional analyses defined developmental and subset-specific programs of gene expression by iNKT cells. In addition, we found that iNKT cells shared an extensive transcriptional program with NK cells, similar in magnitude to that shared with major histocompatibility complex (MHC)-restricted T cells. Notably, the program shared by NK cells and iNKT cells also operated constitutively in γδ T cells and in adaptive T cells after activation. Together our findings highlight a core effector program regulated distinctly in innate and adaptive lymphocytes

Innate Immune Response of Human Alveolar Macrophages during Influenza A Infection

Alveolar macrophages (AM) are one of the key cell types for initiating inflammatory and immune responses to influenza virus in the lung. However, the genome-wide changes in response to influenza infection in AM have not been defined. We performed gene profiling of human AM in response to H1N1 influenza A virus PR/8 using Affymetrix HG-U133 Plus 2.0 chips and verified the changes at both mRNA and protein levels by real-time RT-PCR and ELISA. We confirmed the response with a contemporary H3N2 influenza virus A/New York/238/2005 (NY/238). To understand the local cellular response, we also evaluated the impact of paracrine factors on virus-induced chemokine and cytokine secretion. In addition, we investigated the changes in the expression of macrophage receptors and uptake of pathogens after PR/8 infection. Although macrophages fail to release a large amount of infectious virus, we observed a robust induction of type I and type III interferons and several cytokines and chemokines following influenza infection. CXCL9, 10, and 11 were the most highly induced chemokines by influenza infection. UV-inactivation abolished virus-induced cytokine and chemokine response, with the exception of CXCL10. The contemporary influenza virus NY/238 infection of AM induced a similar response as PR/8. Inhibition of TNF and/or IL-1β activity significantly decreased the secretion of the proinflammatory chemokines CCL5 and CXCL8 by over 50%. PR/8 infection also significantly decreased mRNA levels of macrophage receptors including C-type lectin domain family 7 member A (CLEC7A), macrophage scavenger receptor 1 (MSR1), and CD36, and reduced uptake of zymosan. In conclusion, influenza infection induced an extensive proinflammatory response in human AM. Targeting local components of innate immune response might provide a strategy for controlling influenza A infection-induced proinflammatory response in vivo

NF-κB protects NKT cells from tumor necrosis factor receptor 1-induced death

Semi-invariant natural killer T (NKT) cells are innate-like lymphocytes with immunoregulatory properties. NKT cell survival during development requires signal processing by activated RelA/NF-κB. Nonetheless, the upstream signal(s) integrated by NF-κB in developing NKT cells remains incompletely defined. We show that the introgression of Bcl-xL-coding Bcl2l1 transgene into NF-κB signalling-deficient IκBΔN transgenic mouse rescues NKT cell development and differentiation in this mouse model. We reasoned that NF-κB activation was protecting developing NKT cells from death signals emanating either from high affinity agonist recognition by the T cell receptor (TCR) or from a death receptor, such as tumor necrosis factor receptor 1 (TNFR1) or Fas. Surprisingly, the single and combined deficiency in PKC-θ or CARMA-1-the two signal transducers at the NKT TCR proximal signalling node-only partially recapitulated the NKT cell deficiency observed in IκBΔN tg mouse. Accordingly, introgression of the Bcl2l1 transgene into PKC-θ null mouse failed to rescue NKT cell development. Instead, TNFR1-deficiency, but not the Fas-deficiency, rescued NKT cell development in IκBΔN tg mice. Consistent with this finding, treatment of thymocytes with an antagonist of the inhibitor of κB kinase -which blocks downstream NF-κB activation- sensitized NKT cells to TNF-α-induced cell death in vitro. Hence, we conclude that signal integration by NF-κB protects developing NKT cells from death signals emanating from TNFR1, but not from the NKT TCR or Fas

NF-κB protects NKT cells from tumor necrosis factor receptor 1-induced death

Semi-invariant natural killer T (NKT) cells are innate-like lymphocytes with immunoregulatory properties. NKT cell survival during development requires signal processing by activated RelA/NF-κB. Nonetheless, the upstream signal(s) integrated by NF-κB in developing NKT cells remains incompletely defined. We show that the introgression of Bcl-xL-coding Bcl2l1 transgene into NF-κB signalling-deficient IκBΔN transgenic mouse rescues NKT cell development and differentiation in this mouse model. We reasoned that NF-κB activation was protecting developing NKT cells from death signals emanating either from high affinity agonist recognition by the T cell receptor (TCR) or from a death receptor, such as tumor necrosis factor receptor 1 (TNFR1) or Fas. Surprisingly, the single and combined deficiency in PKC-θ or CARMA-1-the two signal transducers at the NKT TCR proximal signalling node-only partially recapitulated the NKT cell deficiency observed in IκBΔN tg mouse. Accordingly, introgression of the Bcl2l1 transgene into PKC-θ null mouse failed to rescue NKT cell development. Instead, TNFR1-deficiency, but not the Fas-deficiency, rescued NKT cell development in IκBΔN tg mice. Consistent with this finding, treatment of thymocytes with an antagonist of the inhibitor of κB kinase -which blocks downstream NF-κB activation- sensitized NKT cells to TNF-α-induced cell death in vitro. Hence, we conclude that signal integration by NF-κB protects developing NKT cells from death signals emanating from TNFR1, but not from the NKT TCR or Fas

Nur77 controls tolerance induction, terminal differentiation, and effector functions in NKT cells

Natural killer T (NKT) cells are self-reactive lymphocytes, yet how this lineage attains self-tolerance remains unknown. NKT cells constitutively express high levels of Nr4a1-encoded Nur77, a transcription factor that integrates signal strength downstream of the T cell receptor (TCR) within activated thymocytes and peripheral T cells. Nur77 is associated with tolerance induction in conventional T cells but is of hitherto unknown function in NKT cells. Here we report that sustained Nur77 overexpression (Nur77tg) in mouse thymocytes abrogates NKT cell development. Introgression of a rearranged Vα14-Jα18 a-chain gene into the Nur77tg (Nur77tg;Vα14tg) mouse rescued development up to an early precursor stage 0. NKT cells in bone marrow chimeras that reconstituted thymic cellularity developed beyond stage 0 precursors, yielding interleukin-4-producing NKT2 but not interferon-g-producing NKT1 cell subsets. Nonetheless, NKT cells that emerged in these chimeras expressed the exhaustion marker PD1 and responded poorly to glycolipid agonists. Hence, Nur77 integrates signals emanating from the TCR to control NKT cell tolerance, terminal differentiation, and effector functions