Zhong-Bin Deng

Induction of myeloid-derived suppressor cells by tumor exosomes.

Myeloid‐derived suppressor cells (MDSCs) promote tumor progression. The mechanisms of MDSC development during tumor growth remain unknown. Tumor exosomes (T‐exosomes) have been implicated to play a role in immune regulation, however the role of exosomes in the induction of MDSCs is unclear. Our previous work demonstrated that exosomes isolated from tumor cells are taken up by bone marrow myeloid cells. Here, we extend those findings showing that exosomes isolated from T‐exosomes switch the differentiation pathway of these myeloid cells to the MDSC pathway (CD11b+Gr‐1+). The resulting cells exhibit MDSC phenotypic and functional characteristics including promotion of tumor growth. Furthermore, we demonstrated that in vivo MDSC mediated promotion of tumor progression is dependent on T‐exosome prostaglandin E2 (PGE2) and TGF‐β molecules. T‐exosomes can induce the accumulation of MDSCs expressing Cox2, IL‐6, VEGF, and arginase‐1. Antibodies against exosomal PGE2 and TGF‐β block the activity of these exosomes on MDSC induction and therefore attenuate MDSC‐mediated tumor‐promoting ability. Exosomal PGE2 and TGF‐β are enriched in T‐exosomes when compared with exosomes isolated from the supernatants of cultured tumor cells (C‐exosomes). The tumor microenvironment has an effect on the potency of T‐exosome mediated induction of MDSCs by regulating the sorting and the amount of exosomal PGE2 and TGF‐β available. Together, these findings lend themselves to developing specific targetable therapeutic strategies to reduce or eliminate MDSC‐induced immunosuppression and hence enhance host antitumor immunotherapy efficacy.

Adipose Tissue Exosome-Like Vesicles Mediate Activation of Macrophage-Induced Insulin Resistance

OBJECTIVE We sought to determine whether exosome-like vesicles (ELVs) released from adipose tissue play a role in activation of macrophages and subsequent development of insulin resistance in a mouse model. RESEARCH DESIGN AND METHODS ELVs released from adipose tissue were purified by sucrose gradient centrifugation and labeled with green fluorescent dye and then intravenously injected into B6 ob/ob mice (obese model) or B6 mice fed a high-fat diet. The effects of injected ELVs on the activation of macrophages were determined through analysis of activation markers by fluorescence-activated cell sorter and induction of inflammatory cytokines using an ELISA. Glucose tolerance and insulin tolerance were also evaluated. Similarly, B6 mice with different gene knockouts including TLR2, TLR4, MyD88, and Toll-interleukin-1 receptor (TIR) domain–containing adaptor protein inducing interferon-β (TRIF) were also used for testing their responses to the injected ELVs. RESULTS ELVs are taken up by peripheral blood monocytes, which then differentiate into activated macrophages with increased secretion of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). Injection of obELVs into wild-type C57BL/6 mice results in the development of insulin resistance. When the obELVs were intravenously injected into TLR4 knockout B6 mice, the levels of glucose intolerance and insulin resistance were much lower. RBP4 is enriched in the obELVs. Bone marrow–derived macrophages preincubated with recombinant RBP4 led to attenuation of obELV-mediated induction of IL-6 and TNF-α. CONCLUSIONS ELVs released by adipose tissue can act as a mode of communication between adipose tissues and macrophages. The obELV-mediated induction of TNF-α and IL-6 in macrophages and insulin resistance requires the TLR4/TRIF pathway.

Thymus Exosomes-Like Particles Induce Regulatory T Cells

Exosomes released from different types of cells have been proposed to contribute to intercellular communication. We report that thymic exosome-like particles (ELPs) released from cells of the thymus can induce the development of Foxp3+ regulatory T (Treg) cells in the lung and liver. Thymic ELPs also induce the conversion of thymic CD4+CD25− T cells into Tregs. Tregs induced by thymic ELPs suppress the proliferation of CD4+CD25− T cells in vitro and in vivo. We further show that neutralization of TGF-β in ELPs partially reverses thymic ELP-mediated induction of CD4+Foxp3+ T cells in the lung and liver. This study demonstrates that thymic ELPs participate in the induction of Foxp3+ Tregs. Also, TGF-β of thymic ELPs might be required for the generation of Tregs in the peripheral tissues.

Grape Exosome-like Nanoparticles Induce Intestinal Stem Cells and Protect Mice From DSS-Induced Colitis

Food-derived exosome-like nanoparticles pass through the intestinal tract throughout our lives, but little is known about their impact or function. Here, as a proof of concept, we show that the cells targeted by grape exosome-like nanoparticles (GELNs) are intestinal stem cells whose responses underlie the GELN-mediated intestinal tissue remodeling and protection against dextran sulfate sodium (DSS)-induced colitis. This finding is further supported by the fact that coculturing of crypt or sorted Lgr5⁺ stem cells with GELNs markedly improved organoid formation. GELN lipids play a role in induction of Lgr5⁺ stem cells, and the liposome-like nanoparticles (LLNs) assembled with lipids from GELNs are required for in vivo targeting of intestinal stem cells. Blocking β-catenin-mediated signaling pathways of GELN recipient cells attenuates the production of Lgr5⁺ stem cells. Thus, GELNs not only modulate intestinal tissue renewal processes, but can participate in the remodeling of it in response to pathological triggers.

Immature myeloid cells induced by a high-fat diet contribute to liver inflammation.

Chronic inflammation plays a critical role in promoting obesity‐related disorders, such as fatty liver disease. The inflammatory cells that mediate these effects remain unknown. This study investigated the accumulation of immature myeloid cells in the liver and their role in liver inflammation. We found that the accumulation of immature myeloid cells, i.e., CD11b+Ly6ChiLy6G− cells, in the liver of B6 mice fed a high‐fat diet contribute to liver inflammation. Adoptive transfer of CD11b+Ly6ChiLy6G− cells isolated from the liver of obese B6 mice, but not from lean B6 mice, resulted in liver damage that was evident by an increase in the activity of liver transferases in serum. CD11b+Ly6ChiLy6G− cells isolated from the liver of obese mice are more easily activated by way of Toll‐like receptor (TLR) stimulation resulting in interleukin 12 and other inflammatory cytokine expression in an MyD88‐dependent fashion. TLR7‐activated CD11b+Ly6ChiLy6G− cells also enhance liver natural killer T cell (NKT) death in an Fas‐dependent manner. Experiments using mice depleted of Gr‐1+ immature myeloid cells demonstrated the important role of CD11b+Ly6ChiLy6G− in liver inflammation. Repeated injection of exosome‐like particles causes CD11b+ cell activation and subsequent homing to and accumulation of the cells in the liver. Conclusion: Consumption of a high‐fat diet by B6 mice triggers an accumulation of immature myeloid cells in the liver. The immature myeloid cells release proinflammatory cytokines and induce NKT cell apoptosis. Activation‐induced NKT apoptosis further promotes excessive production of Th‐1 cytokines. This diet‐induced accumulation of immature myeloid cells may contribute to obesity‐related liver disease. (HEPATOLOGY 2009.)

Exosomes are endogenous nanoparticles that can deliver biological information between cells

Exosomal particular size of 30-100 nm matches the size criterion for nanoparticles, and opens up the possibility of using exosomes as a nanoparticle drug carrier. More importantly, exosomes released from different types of host cells have different biological effects and targeting specificities. Therefore, depending on the therapeutic goal, different types of exosomes can be combined with specific drugs and serve as carriers so that personalized medicine needs are met. In addition, exosomes do not appear to have cytotoxicity. Based on the perceived advantages of exosomes, they may well serve as a next generation drug delivery mechanism that combines nanoparticle size with a non-cytotoxic effect, target specificity, and a high drug carrying capacity, to make them useful in the treatment of a variety of diseases. This review will focus on exosomes as a biological nanoparticle drug carrier with emphasis on their immune-regulatory activities.

Interspecies communication between plant and mouse gut host cells through edible plant derived exosome-like nanoparticles

SCOPE Exosomes, small vesicles participating in intercellular communication, have been extensively studied recently; however, the role of edible plant derived exosomes in interspecies communication has not been investigated. Here, we investigate the biological effects of edible plant derived exosome-like nanoparticles (EPDENs) on mammalian cells. METHODS AND RESULTS In this study, exosome-like nanoparticles from four edible plants were isolated and characterized. We show that these EPDENs contain proteins, lipids, and microRNA. EPDENs are taken up by intestinal macrophages and stem cells. The results generated from EPDEN-transfected macrophages indicate that ginger EPDENs preferentially induce the expression of the antioxidation gene, heme oxygenase-1 and the anti-inflammatory cytokine, IL-10; whereas grapefruit, ginger, and carrot EPDENs promote activation of nuclear factor like (erythroid-derived 2). Furthermore, analysis of the intestines of canonical Wnt-reporter mice, i.e. B6.Cg-Tg(BAT-lacZ)3Picc/J mice, revealed that the numbers of β-galactosidase(+) (β-Gal) intestinal crypts are increased, suggesting that EPDEN treatment of mice leads to Wnt-mediated activation of the TCF4 transcription machinery in the crypts. CONCLUSION The data suggest a role for EPDEN-mediated interspecies communication by inducing expression of genes for anti-inflammation cytokines, antioxidation, and activation of Wnt signaling, which are crucial for maintaining intestinal homeostasis.

Delivery of therapeutic agents by nanoparticles made of grapefruit-derived lipids

Although the use of nanotechnology for the delivery of a wide range of medical treatments has potential to reduce adverse effects associated with drug therapy, tissue-specific delivery remains challenging. Here we show that nanoparticles made of grapefruit-derived lipids, which we call grapefruit-derived nanovectors (GNVs), can transport chemotherapeutic agents, siRNA, DNA expression vectors and proteins to different types of cells. We demonstrate the in vivo targeting specificity of GNVs by co-delivering therapeutic agents with folic acid, which in turn leads to significantly increasing targeting efficiency to cells expressing folate receptors. The therapeutic potential of GNVs was further demonstrated by enhancing the chemotherapeutic inhibition of tumor growth in two tumor animal models. GNVs are less toxic than nanoparticles made of synthetic lipids and, when injected intravenously into pregnant mice, do not pass the placental barrier, suggesting they may be a useful tool for drug delivery.

Grhl2 Determines the Epithelial Phenotype of Breast Cancers and Promotes Tumor Progression

Until now the essential transcription factor that determines the epithelial phenotype of breast cancer has not been identified and its role in epithelial-to-mesenchymal transition (EMT) and tumor progression remain unclear. Here, by analyzing large expression profiles of human breast cancer cells, we found an extraordinary correlation between the expression of Grainyhead transcription factor Grhl2 and epithelial marker E-cadherin. Knockdown of Grhl2 expression by shRNA in human mammary epithelial cell MCF10A leads to down-regulation of E-cadherin and EMT. Grhl2 is down-regulated in disseminated cancer cells that have undergone EMT, and over-expression of Grhl2 is sufficient to induce epithelial gene expression. Large clinical datasets reveal that expression of Grhl2 is significantly associated with poor relapse free survival and increased risk of metastasis in breast cancer patients. In mouse models, over-expression of Grhl2 significantly promotes tumor growth and metastasis. Further testing of several Grhl2 regulated genes leads to the same conclusions that the tumorigenic and metastatic potentials of tumor cells are linked to epithelial phenotype but not mesenchymal phenotype. In conclusion, our findings indicate that Grhl2 plays an essential role in the determination of epithelial phenotype of breast cancers, EMT and tumor progression.

Targeted Drug Delivery to Intestinal Macrophages by Bioactive Nanovesicles Released from Grapefruit

The gut mucosal immune system is considered to play an important role in counteracting potential adverse effects of food-derived antigens including nanovesicles. Whether nanovesicles naturally released from edible fruit work in a coordinated manner with gut immune cells to maintain the gut in a noninflammatory status is not known. Here, as proof of concept, we demonstrate that grapefruit-derived nanovesicles (GDNs) are selectively taken up by intestinal macrophages and ameliorate dextran sulfate sodium (DSS)-induced mouse colitis. These effects were mediated by upregulating the expression of heme oxygenase-1 (HO-1) and inhibiting the production of IL-1β and TNF-α in intestinal macrophages. The inherent biocompatibility and biodegradability, stability at wide ranges of pH values, and targeting of intestinal macrophages led us to further develop a novel GDN-based oral delivery system. Incorporating methotrexate (MTX), an anti-inflammatory drug, into GDNs and delivering the MTX-GDNs to mice significantly lowered the MTX toxicity when compared with free MTX, and remarkably increased its therapeutic effects in DSS-induced mouse colitis. These findings demonstrate that GDNs can serve as immune modulators in the intestine, maintain intestinal macrophage homeostasis, and can be developed for oral delivery of small molecule drugs to attenuate inflammatory responses in human disease.