Breast cancer cell derived exosomes reduces glycolysis of activated CD8 + T cells in a AKT-mTOR dependent manner.

Cytotoxic CD8+ T cells plays a pivotal role in the adaptive immune system to protect the organism against infections and cancer. During activation and response, T cells undergo a metabolic reprogramming that involves various metabolic pathways, with a predominant reliance on glycolysis to meet their increased energy demands and enhanced effector response. Recently, extracellular vesicles (EVs) known as exosomes have been recognized as crucial signaling mediators in regulating the tumor microenvironment (TME). Recent reports indicates that exosomes may transfer biologically functional molecules to the recipient cells, thereby facilitate cancer progression, angiogenesis, metastasis, drug resistance, and immunosuppression by reprogramming the metabolism of cancer cells. This study sought to enlighten possible involvement of cancer-derived exosomes in CD8 + T cell glucose metabolism and discover a regulated signalome as a mechanism of action. We observed reduction in glucose metabolism due to downregulation of AKT/mTOR signalome in activated CD8 + T cells after cancer derived exosome exposure. In-vivo murine breast tumor studies showed better tumor control and antitumor CD8 + T cell glycolysis and effector response after abrogation of exosome release from breast cancer cells. Summarizing, the present study establishes an immune evasion mechanism of breast cancer cell secreted exosomes that will act as a foundation for future precision cancer therapeutics.

Estimating nitric oxide (NO) from MDSCs by Griess method.

The functional importance of nitric oxide (NO) in the fields of immunology concerning its antimicrobial, anti-tumoral, anti-inflammatory, and immunosuppressive effects have made it inevitable to study its secretion from various cells. Nitrogen oxide synthase (NOS) is the enzyme responsible for synthesizing NO and its three isoforms function in a cell-dependent manner. NO is oxidized rapidly to Reactive nitrogen oxide species (RNOS) through which the roles of NO are being carried out. One of the major immune cells secreting NO is myeloid-derived suppressor cells (MDSCs). The function of these MDSCs in the suppression of T-cell proliferation as well as T-cell differentiation is found to be dependent on NO secretion. Apart from T-cell suppressive activity, NO is also known to interfere with natural killer (NK) cell functions. A convenient method to estimate NO secretion is by using Griess reagent named after Johann Peter Griess. In this method, NO reacts with the reagents to form a colored azo dye detectable using a microplate reader at a wavelength of 548nm. In this chapter, we summarized the detailed method of estimating NO from MDSCs by the Griess method.

Administration of rIL-33 Restores Altered mDC/pDC Ratio, MDSC Frequency, and Th-17/Treg Ratio during Experimental Cerebral Malaria.

The onset of malaria causes the induction of various inflammatory markers in the host's body, which in turn affect the body's homeostasis and create several cerebral complications. Polarization of myeloid-derived suppressor cells (MDSCs) from the classically activated M1 to alternatively activated M2 phenotype increases the secretion of pro-inflammatory molecules. Treatment with recombinant IL-33 (rIL-33) not only alters this MDSC's polarization but also targets the glycolysis pathway of the metabolism in MDSCs, rendering them less immunosuppressive. Along with that, the Helper T-cells subset 17 (Th17)/T regulatory cells (Tregs) ratio is skewed towards Th17, which increases inflammation by producing more IL-17. However, treating with rIL-33 also helps to restore this ratio, which brings back homeostasis. During malaria infection, there is an upregulation of IL-12 production from dendritic cells along with a distorted myeloid dendritic cells (mDC)/plasmacytoid dendritic cells (pDC) ratio towards mDCs promoting inflammation. Administering rIL-33 will also subvert this IL-12 production and increase the population of pDC in the host's immune system during malaria infection, thus restoring mDC/pDC to homeostasis. Therefore, treatment with rIL-33 to reduce the pro-inflammatory signatures and maintenance of immune homeostasis along with the increase in survivability could be a potential therapeutic approach for cerebral malaria.

Administration of soluble gp130Fc disrupts M-1 macrophage polarization, dendritic cell activation, MDSC expansion and Th-17 induction during experimental cerebral malaria.

Regulatory effect of IL-6 on various immune cells plays a crucial role during experimental cerebral malaria pathogenesis. IL-6 neutralization can restore distorted ratios of myeloid dendritic cells and plasmacytoid dendritic cells as well as the balance between Th-17 and T-regulatory cells. IL-6 can also influence immune cells through classical and trans IL-6 signalling pathways. As trans IL-6 signalling is reportedly involved during malaria pathogenesis, we focused on studying the effects of trans IL-6 signalling blockade on various immune cell populations and how they regulate ECM progression. Results show that administration of sgp130Fc recombinant chimera protein lowers the parasitemia, increases the survivability of Plasmodium berghei ANKA infected mice, and restores the distorted ratios of M1/M2 macrophage, mDC/pDC, and Th-17/Treg. IL-6 trans signalling blockade has been found to affect both expansion of myeloid derived suppressor cells (MDSCs) and expression of inflammatory markers on them during Plasmodium berghei ANKA infection indicating that trans IL-6 signalling might regulate various immune cells and their function during ECM. In this work for the first time, we delineate the effect of sgp130Fc administration on influencing the immunological changes within the host secondary lymphoid organ during ECM induced by Plasmodium berghei ANKA infection.