Cells have the ability to communicate with their immediate and distant neighbors through the release of extracellular vesicles (EVs). EVs facilitate intercellular signaling through the packaging of specific cargo in all type of cells, and perturbations of EV biogenesis, sorting, release and uptake is the basis of a number of disorders. In this review, we summarize recent advances of the complex roles of the sphingolipid ceramide and lysosomes in the journey of EV biogenesis to uptake.

According to the endosymbiotic theory of mitochondrial origin, an α‐proteobacterium entered a prokaryotic cell and, through symbiosis, evolved into the mitochondria—the powerhouse of the cell. Like other bacteria, the α‐proteobacteria generate their own extracellular vesicles (EVs), a trait that was passed onto the mitochondria, enabling them to generate mitochondria‐derived vesicles (MDVs). MDVs, similar to small EVs (sEVs), are vesicles ranging from 30 to 200 nm in diameter and carry cargo for degradation by lysosomes and peroxisomes. MDVs share several features with sEVs, including targeted cargo degradation, biogenesis, packaging into multivesicular bodies, nucleic acid and protein transportation, induction of immune responses, and surface antigen presentation. MDVs may also be released from the cell in a manner similar to sEVs, potentially influencing intercellular communication and immune responses. Furthermore, the presence of MDVs presents opportunities for early disease detection, including neurodegenerative disorders and cancer. In this review, we explore the differences and similarities between MDVs and EVs, including their roles in immunity.

Smac mimetic compounds (SMCs) are small molecule drugs that sensitize cancer cells to TNF-α-induced cell death and have multiple immunostimulatory effects through alterations in NF-κB signaling. The combination of SMCs with immunotherapies has been reported to result in durable cures of up to 40% in syngeneic, orthotopic murine glioblastoma (GBM) models. Herein, we find that SMC resistance is not due to a cell-intrinsic mechanism of resistance. We thus evaluated the contribution of GBM and brain stromal components to identify parameters leading to SMC efficacy and resistance. The common physiological features of GBM tumors, such as hypoxia, hyaluronic acid, and glucose deprivation were found not to play a significant role in SMC efficacy. SMCs induced the death of microglia and macrophages, which are the major immune infiltrates in the tumor microenvironment. This death of microglia and macrophages then enhances the ability of SMCs to induce GBM cell death. Conversely, astrocytes promoted GBM cell growth and abrogated the ability of SMCs to induce death of GBM cells. The astrocyte-mediated resistance can be overcome in the presence of exogenous TNF-α. Overall, our results highlight that SMCs can induce death of microglia and macrophages, which then provides a source of death ligands for GBM cells, and that the targeting of astrocytes is a potential mechanism for overcoming SMC resistance for the treatment of GBM.

A dual immunotherapy approach employing small-molecule inhibitors of apoptosis (IAP) protein antagonists in combination with innate immune stimuli has proven to be highly synergistic and effective ...

Deregulation of mRNA translation engenders many human disorders, including obesity, neurodegenerative diseases, and cancer, and is associated with pathogen infections. The role of eIF4E-dependent translational control in macrophage inflammatory responses in vivo is largely unexplored. In this study, we investigated the involvement of the translation inhibitors eIF4E-binding proteins (4E-BPs) in the regulation of macrophage inflammatory responses in vitro and in vivo. We show that the lack of 4E-BPs exacerbates inflammatory polarization of bone marrow–derived macrophages and that 4E-BP–null adipose tissue macrophages display enhanced inflammatory gene expression following exposure to a high-fat diet (HFD). The exaggerated inflammatory response in HFD-fed 4E-BP–null mice coincides with significantly higher weight gain, higher Irf8 mRNA translation, and increased expression of IRF8 in adipose tissue compared with wild-type mice. Thus, 4E-BP–dependent translational control limits, in part, the proinflammatory response during HFD. These data underscore the activity of the 4E-BP–IRF8 axis as a paramount regulatory mechanism of proinflammatory responses in adipose tissue macrophages. Key Points The lack of 4E-BPs promotes Mϕ inflammatory responses. 4E-BP–null mice are prone to HFD-induced obesity. 4E-BPs control translation of Irf8.

Autophagy is a fundamental catabolic process essential for the maintenance of cellular and tissue homeostasis, as well as directly contributing to the control of invading pathogens. Unsurprisingly, this process becomes critical in supporting cellular dysregulation that occurs in cancer, particularly the tumor microenvironments and their immune cell infiltration, ultimately playing a role in responses to cancer therapies. Therefore, understanding “cancer autophagy” could help turn this cellular waste-management service into a powerful ally for specific therapeutics. For instance, numerous regulatory mechanisms of the autophagic machinery can contribute to the anti-tumor properties of oncolytic viruses (OVs), which comprise a diverse class of replication-competent viruses with potential as cancer immunotherapeutics. In that context, autophagy can either: promote OV anti-tumor effects by enhancing infectivity and replication, mediating oncolysis, and inducing autophagic and immunogenic cell death; or reduce OV cytotoxicity by providing survival cues to tumor cells. These properties make the catabolic process of autophagy an attractive target for therapeutic combinations looking to enhance the efficacy of OVs. In this article, we review the complicated role of autophagy in cancer initiation and development, its effect on modulating OVs and immunity, and we discuss recent progress and opportunities/challenges in targeting autophagy to enhance oncolytic viral immunotherapy.