In many aggressive cancers, such as glioblastoma multiforme (GBM), progression is enabled by local immunosuppression driven by the accumulation of regulatory T cells (Treg) and myeloid-derived suppressor cells (MDSC). However, the mechanistic details of how Treg and MDSC are recruited in various tumors is not yet well understood. Here we report that macrophages and microglia within the glioma microenvironment produce CCL2, a chemokine that is critical for recruiting both CCR4+ Treg and CCR2+Ly-6C+ monocytic MDSC in this disease setting. In murine gliomas, we established novel roles for tumor-derived CCL20 and osteoprotegerin in inducing CCL2 production from macrophages and microglia. Tumors grown in CCL2 deficient mice failed to maximally accrue Treg and monocytic MDSC. In mixed-bone marrow chimera assays, we found that CCR4-deficient Treg and CCR2-deficient monocytic MDSC were defective in glioma accumulation. Further, administration of a small molecule antagonist of CCR4 improved median survival in the model. In clinical specimens of GBM, elevated levels of CCL2 expression correlated with reduced overall survival of patients. Lastly, we found that CD163-positive infiltrating macrophages were a major source of CCL2 in GBM patients. Collectively, our findings show how glioma cells influence the tumor microenvironment to recruit potent effectors of immunosuppression that drive progression.

Andropogon gerardii seed obtained from Kansas and Illinois was grown in a controlled environment in their own and each other's soils, with and without arbuscular mycorrhizal fungi (AMF). Each ecotype grew comparatively better in its own soil indicating adaptation to its soil of origin. Overall, A. gerardii benefited more from AMF in low-nutrient Kansas soil than Illinois soil. The two ecotypes, however, did not benefit equally from mycorrhizal infection. The Kansas ecotype was three times more responsive to mycorrhizal infection in the Kansas soil than was the Illinois ecotype. Our results indicate that plant adaptation to the nutrient levels of their local soils is likely to be due, at least in part, to a shift in their dependence on mycorrhizal fungi. The Illinois ecotype of A. gerardii has evolved a reduced dependence upon these fungi and greater reliance on a more highly branched root system. In contrast, the Kansas ecotype had a significantly coarser root system and invested proportionately greater carbon in the symbiotic association with AMF as measured by spore production. This study provides the first demonstration that plants can adapt to changing soil nutrient levels by shifting their dependence on AMF. This result has broad implications for our understanding of the role of these fungi in agricultural systems.

Enteroviruses are recognized as important pathogens in pediatric patients; however, they are often overlooked as etiologic agents of disease in adults. Here, we report a case of echovirus 18-associated severe systemic infection and acute liver failure in an adult hematopoietic stem cell transplant recipient. Additionally, we illustrate the utility of molecular methods for the detection and typing of enteroviral infections.

<div>Abstract<p>In many aggressive cancers, such as glioblastoma multiforme, progression is enabled by local immunosuppression driven by the accumulation of regulatory T cells (Treg) and myeloid-derived suppressor cells (MDSC). However, the mechanistic details of how Tregs and MDSCs are recruited in various tumors are not yet well understood. Here we report that macrophages and microglia within the glioma microenvironment produce CCL2, a chemokine that is critical for recruiting both CCR4⁺ Treg and CCR2⁺Ly-6C⁺ monocytic MDSCs in this disease setting. In murine gliomas, we established novel roles for tumor-derived CCL20 and osteoprotegerin in inducing CCL2 production from macrophages and microglia. Tumors grown in CCL2-deficient mice failed to maximally accrue Tregs and monocytic MDSCs. In mixed-bone marrow chimera assays, we found that CCR4-deficient Treg and CCR2-deficient monocytic MDSCs were defective in glioma accumulation. Furthermore, administration of a small-molecule antagonist of CCR4 improved median survival in the model. In clinical specimens of glioblastoma multiforme, elevated levels of CCL2 expression correlated with reduced overall survival of patients. Finally, we found that CD163-positive infiltrating macrophages were a major source of CCL2 in glioblastoma multiforme patients. Collectively, our findings show how glioma cells influence the tumor microenvironment to recruit potent effectors of immunosuppression that drive progression. <i>Cancer Res; 76(19); 5671–82. ©2016 AACR</i>.</p></div>

<p>(A) GL261 cells were orthotopically implanted into the right hemisphere of syngeneic immunocompetent C57BL/6 mice. At 1 week post-intracranial (i.c.) injection whole brains were homogenized followed by Percoll gradient separation of leukocytes and non-leukocytes. qRT-PCR was performed for CCL2 in mice intracranially-injected with GL261 cells (n = 4) or PBS-injected controls (n = 3). (B) Detection of CCL2 protein in both brain hemispheres at 1 week-i.c. GL261 (n = 3). (C) Immunoreactivity for CCL2 was detected at 1 week post-GL261 injection. 20Ã- and 63Ã- magnification. Scale bar = 50 microm. (D) qRT-PCR for CCL1, CCL28, CCL2, CCL22, CCL17, and CCL20 from non-leukocytes (NL) and leukocytes (L) as in (A). Images in C are representative of 3 independent replicates. Data are representative of at least 2 independent experiments. Data are represented as mean {plus minus} SEM; *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001 by one-way ANOVA with Tukey's multiple comparisons test (A, D) or Student's t test (B).</p>

<p>Word document file containing supplementary materials and methods, supplementary figure legends, and supplementary table</p>

<p>CD45.1+ recipient mice were irradiated and reconstituted with CD45.1+ WT marrow and CD45.2+ Ccr4-/- marrow. After at least 6 weeks of reconstitution, mice were implanted with GL261 tumors and brain tumor-infiltrating cells were quantified. Data are representative of at least 2 independent experiments. Data are represented as mean {plus minus} SEM; *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001 by Student's t test. n.s., not significant.</p>

<p>(A-G) Kaplan-Meier survival curves generated from TCGA data using GBM patients segregated by gene expression for a panel of putative Treg and MDSC recruiting chemokines. (H) GBM patient tissue array stained for CCL2. (I) Key showing CCL2 score corresponding to GBM patient cores. Scale bar = 7 mm. TCGA, The Cancer Genome Atlas. Survival curves were compared with the Log-rank test.</p>