CD205+ polymorphonuclear myeloid-derived suppressor cells suppress antitumor immunity by overexpressing GLUT3.

Myeloid-derived suppressor cells (MDSCs) are responsible for antitumor immunodeficiency in tumor-bearing hosts. Primarily, MDSCs are classified into 2 groups: monocytic (M)-MDSCs and polymorphonuclear (PMN)-MDSCs. In most cancers, PMN-MDSCs (CD11b+ Ly6Clow Ly6G+ cells) represent the most abundant MDSC subpopulation. However, the functional and phenotypic heterogeneities of PMN-MDSC remain elusive, which delays clinical therapeutic targeting decisions. In the 4T1 murine tumor model, CD11b+ Ly6Glow PMN-MDSCs were sensitive to surgical and pharmacological interventions. By comprehensively analyzing 64 myeloid cell-related surface molecule expression profiles, cell density, nuclear morphology, and immunosuppressive activity, the PMN-MDSC population was further classified as CD11b+ Ly6Glow CD205+ and CD11b+ Ly6Ghigh TLR2+ subpopulations. The dichotomy of PMN-MDSCs based on CD205 and TLR2 is observed in 4T07 murine tumor models (but not in EMT6). Furthermore, CD11b+ Ly6Glow CD205+ cells massively accumulated at the spleen and liver of tumor-bearing mice, and their abundance correlated with in situ tumor burdens (with or without intervention). Moreover, we demonstrated that CD11b+ Ly6Glow CD205+ cells were sensitive to glucose deficiency and 2-deoxy-d-glucose (2DG) treatment. Glucose transporter 3 (GLUT3) knockdown by siRNA significantly triggered apoptosis and reduced glucose uptake in CD11b+ Ly6Glow CD205+ cells, demonstrating the dependence of CD205+ PMN-MDSCs survival on both glucose uptake and GLUT3 overexpression. As GLUT3 has been recognized as a target for the rescue of host antitumor immunity, our results further directed the PMN-MDSC subsets into the CD205+ GLUT3+ subpopulation as future targeting therapy.

Skeletal muscle stem cells confer maturing macrophages anti-inflammatory properties through insulin-like growth factor-2.

Cytokines produced by immune cells have been demonstrated to act on muscle stem cells (MuSCs) and direct their fate and behavior during muscle repair and regeneration. Nevertheless, it is unclear whether and how MuSCs can also in turn modulate the properties of immune cells. Here, we showed that in vitro expanded MuSCs exhibited a potent anti-inflammatory effect when infused into mice suffering from inflammatory bowel disease (IBD). Supernatant conditioned by MuSCs similarly ameliorated IBD. This beneficial effect of MuSCs was not observed when macrophages were depleted. The MuSC supernatant was found to greatly attenuate the expression of inflammatory cytokines but increase the expression of programmed death-ligand 1 in macrophages treated with lipopolysaccharide and interferon gamma. Further analysis revealed that MuSCs produce a large amount of insulin-like growth factor-2 (IGF-2) that instructs maturing macrophages to undergo oxidative phosphorylation and thus acquire anti-inflammatory properties. Interestingly, the IGF-2 production by MuSCs is much higher than by mesenchymal stem cells. Knockdown or neutralization of IGF-2 abrogated the anti-inflammatory effects of MuSCs and their therapeutic efficacy on IBD. Our study demonstrated that MuSCs possess a strong anti-inflammatory property and the bidirectional interactions between immune cells and MuSCs have important implications in muscle-related physiological and pathological conditions.

Development of RBC Membrane Antigen Arrays for Validating Blood Grouping Reagents.

Antibody reagents have been remained as a standard approach to characterize blood group (BG) antigens in clinic. The specificity and cross-reactivity of these BG antibodies are routine detected using the gel microcolumn assay (GMA). However, the GMA is neither specific nor sensitive, thus increasing the risk of improperly matched RBC transfusions. In this work, we describe a bead-based RBC membrane antigen array to detect BG antibody-antigen binding with ∼700-fold higher sensitivity and dynamic range than the GMA. RBC membrane antigen arrays were fabricated using fragmented RBC membranes highly enriched in BG panel antigens. The arrays were then used to screen the interactions of 15 BG reagents to three antigen panels. The majority of the antibody reactions (i.e., 86.7%; 39/45) aligned with those obtained with the GMA. The six cross-reactive, nonspecific antibody reactions identified only by our arrays (i.e., 13.3%; 6/45) were confirmed by agglutination inhibition and genotyping assays. These results demonstrate that our RBC membrane antigen array has great potential in screening BG antibodies and improving the safety of RBC transfusions.

[Anti-phagocytosis mechanism of SalK/SalR, a two-component regulatory system of Streptococcus suis serotype 2].

OBJECTIVE: To determine the role of the two-component regulatory system (TCS) SalK/SalR in the resistance of Streptococcus suis serotype 2 (SS2) phagocytosed by THP-1-derived macrophages (THP-Mphi). METHODS: Using transmission electron microscopy (TEM), the capsular differences between the wild-type strain 05ZYH33 and the mutant δsalKR were observed. The interactions of SS2 with THP-Mphi were monitored by Gram staining and immunofluorescence cytochemistry. The anti-phagocytic activity of SS2 was evaluated by the construction of phagocytosis model of THP-Mphi. RESULTS: The TEM showed that in the mutant δsalKR, the capsule was lost; the Gram staining and immunofluorescence imaging revealed that the absence of salKR caused more SS2 were engulfed by THP-Mphi. The phagocytosis model of THP-Mphi cells further demonstrated that the mutant δsalKR was easier to be phagocytosed by THP-1 cells than the wild-type strain. CONCLUSION: The SalK/SalR regulatory system resists the phagocytosis by THP- Mphi through the capsular formation, but the mechanism of how it regulates the formation of the capsule needs further elucidation.

Antiproliferative effect of the Ginkgo biloba extract is associated with the enhancement of cytochrome P450 1B1 expression in estrogen receptor-negative breast cancer cells.

Ginkgo biloba is a dioecious tree and its extract is a complex mixture that has been used for thousands of years to treat a variety of ailments in traditional Chinese medicine. The aim of this study was to present our observations on the inhibitory effects of different Ginkgo biloba extracts on human breast cancer cell proliferation and growth. Our results demonstrated that treatment of MCF-7 and MDA-MB-231 human breast cancer cells with Ginkgo biloba leaves and ginkgo fruit extract inhibited cell proliferation. It was also observed that this inhibition was accompanied by the enhancement of cytochrome P450 (CYP) 1B1 expression in MDA-MB-231 cells. In addition, treatment with ginkgo fruit extract resulted in a higher CYP1B1 expression in MDA-MB-231 cells compared to treatment with the Ginkgo biloba leaves extract. Our results suggested that the inhibitory effects of the Ginkgo biloba extract on estrogen receptor-negative breast cancer proliferation and the induction of CYP1B1 expression may be exerted through an alternative pathway, independent of the estrogen receptor or the aryl hydrocarbon receptor pathway.