No abstract

Salmonella exploit host-derived nitrate for growth in the lumen of the inflamed intestine. The generation of host-derived nitrate is dependent on Nos2 , which encodes inducible nitric oxide synthase (iNOS), an enzyme that catalyzes nitric oxide (NO) production. However, the cellular sources of iNOS and, therefore, NO-derived nitrate used by Salmonella for growth in the lumen of the inflamed intestine remain unidentified. Here, we show that iNOS-producing inflammatory monocytes infiltrate ceca of mice infected with Salmonella . In addition, we show that inactivation of type-three secretion system (T3SS)-1 and T3SS-2 renders Salmonella unable to induce CC- chemokine receptor-2- and CC-chemokine ligand-2-dependent inflammatory monocyte recruitment. Furthermore, we show that the severity of the pathology of Salmonella - induced colitis as well as the nitrate-dependent growth of Salmonella in the lumen of the inflamed intestine are reduced in mice that lack Ccr2 and, therefore, inflammatory monocytes in the tissues. Thus, inflammatory monocytes provide a niche for Salmonella expansion in the lumen of the inflamed intestine.

29Mutations in the p53 tumor suppressor occur very frequently in human cancer. 30Often, such mutations lead to the constitutive overproduction of mutant p53 31 (mtp53) proteins, which can exert a cancer-promoting gain-of-function (GOF). We 32 have identified a novel mechanism by which mtp53 controls both cell-autonomous 33 and non-cell autonomous signaling to promote cancer cell survival and suppress 34 tumor immune surveillance. Mtp53 interferes with the function of the cytoplasmic 35 DNA sensing machinery, cGAS-STING-TBK1-IRF3, that controls the activation of 36 the innate immune response. We find that mtp53, but not wildtype p53, binds to 37 TANK binding protein kinase (TBK1) and inhibits both its basal and agonist-38 induced activity. The association of mtp53 with TBK1 prevents the formation of a 39 trimeric complex between TBK1-STING-IRF3, which is required for activation, 40 nuclear translocation and transcriptional activity of IRF3. Mtp53 knockdown 41 restores TBK1 activity, resulting in the transcriptional induction of IRF3 target 42 genes and IRF3-dependent apoptosis. Furthermore, inactivation of innate immune 43 signaling by mtp53 alters cytokine production resulting in immune evasion. 44 Restored TBK1 signaling was sufficient to bypass mtp53 and reactivate cell-45 autonomous and non-cell autonomous tumor control. Thus, overriding mtp53's 46 inhibition of this cytosolic DNA sensing pathway may ultimately lead to restored 47 an oncogenic mtp53 protein that exhibits gain-of function activities.(5) Recently, it has been 62 reported that 91% of cancers that have a mtp53 allele have lost their second allele through 63 mutation or chromosomal loss.(6) Furthermore, the presence of mtp53 correlates with increased 64 chromosomal instability leading to loss of tumor suppressor genes and amplification of 65 oncogenes.(6, 7) 66 Aneuploidy is considered one of the hallmarks of cancer and is thought to play an 67 important role in driving tumor cell evolution.(8) Aneuploidy has been shown to provoke cell 68 cycle arrest, senescence, increased pro-inflammatory cytokine production and upregulation of 69 Natural Killer (NK) cell ligands in tumor cells, resulting in their subsequent killing by NK 70 cells.(9) In an in vivo setting, the increased production of pro-inflammatory cytokines coupled 71 with increased NK cell ligand expression permits the recruitment of immune cells and clearance 72 of abnormal cells.(10) Thus, in addition to the cell-autonomous mechanisms that suppress 73 genetic instability, cells also utilize non-cell autonomous mechanisms to signal their own 74 destruction.(9) However, chromosomal instability can give rise to micronuclei, which are prone 75 to rupturing and releasing the DNA into the cytoplasm.(11) DNA leaked into the cytoplasm is 76 recognized by the DNA binding protein, cyclic GMP-AMP synthase (cGAS), which in turn triggers 77 innate immune signaling that results in the production of type I interferons.(12) Mechanistically, 78 DNA promotes cGAS homodimerization and production of the secon...

Although murine γδ T cells are largely considered innate immune cells, they have recently been reported to form long-lived memory populations. Much remains unknown about the biology and specificity of memory γδ T cells. Here, we interrogated intestinal memory Vγ4Vδ1 T cells generated after foodborne Listeria monocytogenes (Lm) infection to uncover an unanticipated complexity in the specificity of these cells. Deep TCR sequencing revealed that a subset of non-canonical Vδ1 clones are selected by Lm infection, consistent with antigen-specific clonal expansion. Ex vivo stimulations and in vivo heterologous challenge infections with diverse pathogenic bacteria revealed that Lm -elicited memory Vγ4Vδ1 T cells are broadly reactive. The Vγ4Vδ1 T cell recall response to Lm, Salmonella enterica serovar Typhimurium (STm) and Citrobacter rodentium was largely mediated by the γδTCR as internalizing the γδTCR prevented T cell expansion. Both broadly-reactive canonical and pathogen-selected non-canonical Vδ1 clones contributed to memory responses to Lm and STm. Interestingly, some non-canonical γδ T cell clones selected by Lm infection also responded after S Tm infection, suggesting some level of cross-reactivity. These findings underscore the promiscuous nature of memory γδ T cells and suggest that pathogen-elicited memory γδ T cells are potential targets for broad-spectrum anti-infective vaccines.