Fusobacterium nucleatum is implicated in accelerating colorectal cancer (CRC) and is found within metastatic CRC cells in patient biopsies. Here, we found that bacterial invasion of CRC cells and cocultured immune cells induced a differential cytokine secretion that may contribute to CRC metastasis. We used a modified galactose kinase markerless gene deletion approach and found that F. nucleatum invaded cultured HCT116 CRC cells through the bacterial surface adhesin Fap2. In turn, Fap2-dependent invasion induced the secretion of the proinflammatory cytokines IL-8 and CXCL1, which are associated with CRC progression and promoted HCT116 cell migration. Conditioned medium from F. nucleatum–infected HCT116 cells caused naïve cells to migrate, which was blocked by depleting CXCL1 and IL-8 from the conditioned medium. Cytokine secretion from HCT116 cells and cellular migration were attenuated by inhibiting F. nucleatum host-cell binding and entry using galactose sugars, l-arginine, neutralizing membrane protein antibodies, or fap2 deletion. F. nucleatum also induces the mobilization of immune cells in the tumor microenvironment. However, in neutrophils and macrophages, the bacterial-induced secretion of cytokines was Fap2 independent. Thus, our findings show that F. nucleatum both directly and indirectly modulates immune and cancer cell signaling and migration. Because increased IL-8 and CXCL1 production in tumors is associated with increased metastatic potential and cell seeding, poor prognosis, and enhanced recruitment of tumor-associated macrophages and fibroblasts, we propose that inhibition of host-cell binding and invasion, potentially through vaccination or novel galactoside compounds, could be an effective strategy for reducing F. nucleatum–associated CRC metastasis.

Fusobacterium nucleatum is implicated in the acceleration of colorectal cancer (CRC), y et the mechanisms by which this bacterium modulates the tumor microenvironment remain understudied. Here we show that binding and cellular invasion of CRC cells selectively induces the secretion of the pro-inflammatory and metastatic cytokines IL-8 and CXCL1, which we then show induces robust migration of HCT116 cancer cells. Next, we demonstrate that cytokine signaling by cancer cells is largely driven by invasion coordinated by the surface adhesin Fap2. By contrast, we show that F. nucleatum induced secretion of CCL3, CXCL2, and TNFα cytokines from neutrophils and macrophages is Fap2 independent. Finally, we show that inhibiting F. nucleatum host-cell binding and entry using galactose sugars, neutralizing membrane antibodies, and deletion of the fap2 gene, lead to attenuated cytokine secretion and cellular migration. As elevated IL-8 and CXCL1 levels in cancer have been associated with increased metastatic potential and cell seeding, poor prognosis, and enhanced recruitment of tumor-associated macrophages and fibroblasts within tumor microenvironments, these data show that F. nucleatum directly and indirectly modulates immune and cancer cell signaling and migration. In conclusion, as viable F. nucleatum were previously shown to migrate within metastatic CRC cells, we propose that inhibition of host cell binding and invasion, potentially through vaccination or novel galactoside compounds, could be an effective strategy for reducing F. nucleatum -induced signaling that drives metastasis and cancer cell seeding. ________________________________________________________________________________________ microbe-accelerated cancers. Two recent studies reported that F. nucleatum directly induces cancer cell metastasis through NF-κB increased expression of Keratin 7 (KRT7) ( 11 ), as well as increased expression of caspase activation and recruitment domain 3 (CARD3), and downregulation of E-cadherin ( 12 ). Herein we add to the mechanisms used by F. nucleatum to induce cellular migration. We show that direct binding and invasion of host cancer and immune cells by F. nucleatum induces the secretion of the proinflammatory and prometastatic cytokines IL-8 and CXCL1, and that conditioned media from F. nucleatum infected HCT116 CRC cells causes non-Fusobacterium exposed cells to migrate towards this cytokine rich media.Chemokines/cytokines play a crucial role in tumor initiation, progression, and metastasis ( 13 ). Initially discovered as chemotactic mediators of leukocytes, they are now known to be secreted by several cell types and can be expressed constitutively or induced by inflammatory stimuli, including bacterial infections, and function in a variety of roles including cell survival, proliferation, angiogenesis, and cell migration. In cancer, chemokines mainly function in regulating angiogenesis, activating tumor-specific immune responses, and directly stimulating the tumor through autocrine or paracrine mechanisms ( 13 ).The cytoki...

We previously showed that rhesus macaques neonatally infected with simian immunodeficiency virus (SIV) do not develop SIV encephalitis (SIVE) and maintain low brain viral loads despite having similar plasma viral loads compared to SIV-infected adults. We hypothesize that differences in myeloid cell populations that are the known target of SIV and HIV in the brain contribute to the lack of neonatal susceptibility to lentivirus-induced encephalitis. Using immunohistochemistry and immunofluorescence microscopy, we examined the frontal cortices from uninfected and SIV-infected infant and adult macaques (n = 8/ea) as well as adults with SIVE (n = 4) to determine differences in myeloid cell populations. The number of CD206+ brain perivascular macrophages (PVMs) was significantly greater in uninfected infants than in uninfected adults and was markedly lower in SIV-infected infants while microglia numbers were unchanged across groups. CD206+ PVMs, which proliferate after infection in SIVinfected adults, did not undergo proliferation in infants. While virtually all CD206+ cells in adults are also CD163+, infants have a distinct CD206 single-positive population in addition to the double-positive population commonly seen in adults. Notably, we found that more than 60% of these unique CD206+CD163− PVMs in SIV-infected infants were positive for cleaved caspase-3, an indicator of apoptosis, and that nearly 100% of this subset were concomitantly positive for the necroptosis marker receptorinteracting protein kinase-3 (RIP3). These findings show that distinct subpopulations of PVMs found in infants undergo programmed cell death instead of proliferation following SIV infection, which may lead to the absence of PVM-dependent SIVE and the limited size of the virus reservoir in the infant brain.

A boron cluster is used to template a hybrid molecular scaffold capable of killing multiple pathogenic and antibiotic-resistant bacterial strains.