Functional platelet-derived mitochondria induce the release of human neutrophil microvesicles.

Inflammation is an essential process of host defense against infections, illness, or tissue damage. Polymorphonuclear neutrophils (PMN) are among the first immune cells involved in acute inflammatory responses and are on the front line in the fight against bacterial infections. In the presence of bacterial fragments, PMN release inflammatory mediators, enzymes, and microvesicles in the extracellular milieu to recruit additional immune cells required to eliminate the pathogens. Recent evidence shows that platelets (PLTs), initially described for their role in coagulation, are involved in inflammatory responses. Furthermore, upon activation, PLT also release functional mitochondria (freeMitos) within their extracellular milieu. Mitochondria share characteristics with bacterial and mitochondrial damage-associated molecular patterns, which are important contributors in sterile inflammation processes. Deep sequencing transcriptome analysis demonstrates that freeMitos increase the mitochondrial gene expression in PMN. However, freeMitos do not affect the mitochondrial-dependent increase in oxygen consumption in PMN. Interestingly, freeMitos significantly induce the release of PMN-derived microvesicles. This study provides new insight into the role of freeMitos in the context of sterile inflammation.

Molecular characterization of the anticancer properties associated with bee venom and its components in glioblastoma multiforme.

Glioblastoma multiforme (GBM) is a frequent form of malignant glioma. Strategic therapeutic approaches to treat this type of brain tumor currently involves a combination of surgery, radiotherapy and chemotherapy. Nevertheless, survival of GBM patients remains in the 12-15 months range following diagnosis. Development of novel therapeutic approaches for this malignancy is therefore of utmost importance. Interestingly, bee venom and its components have shown promising anti-cancer activities in various types of cancer even though information pertaining to GBMs have been limited. The current work was thus undertaken to better characterize the anti-cancer properties of bee venom and its components in Hs683, T98G and U373 human glioma cells. MTT-based cell viability assays revealed IC50 values of 7.12, 15.35 and 7.60 µg/mL for cell lines Hs683, T98G and U373 treated with bee venom, respectively. Furthermore, melittin treatment of these cell lines resulted in IC50 values of 7.77, 31.53 and 12.34 µg/mL, respectively. Cell viability assessment by flow cytometry analysis confirmed signs of late apoptosis and necrosis after only 1 h of treatment with either bee venom or melittin in all three cell lines. Immunoblotting-based quantification of apoptotic markers demonstrated increased expression of Bak and Bax, while Caspsase-3 levels were significantly lower when compared to control cells. Quantification by qRT-PCR showed increased expression levels of long non-coding RNAs RP11-838N2.4 and XIST in glioma cells treated with either bee venom or melittin. Overall, this study provides preliminary insight on molecular mechanisms via which bee venom and its main components can impact viability of glioma cells and warrants further investigation of its anticancer potential in gliomas.

Evaluating the mitochondrial activity and inflammatory state of dimethyl sulfoxide differentiated PLB-985 cells.

Neutrophils play a key role in the innate immunity with their ability to generate and release inflammatory mediators that promote the inflammatory response and consequently restore the hemostasis. As active participants in several steps of the normal inflammatory response, neutrophils are also involved in chronic inflammatory diseases such as asthma, atherosclerosis, and arthritis. Given their dual role in the modulation of inflammation, regulating the inflammatory response of neutrophils has been suggested as an important therapeutic approach by numerous researchers. The neutrophils have a relatively short lifespan, which can be problematic for some in vitro experiments. To address this issue, researchers have used the human monomyelocyte cell line PLB-985 as an in vitro model for exploratory experiments addressing neutrophil-related physiological functions. PLB-985 cells can be differentiated into a neutrophil-like phenotype upon exposure to several agonists, including dimethyl sulfoxide (DMSO). Whether this differentiation of PLB-985 affects important features related to the neutrophil's normal functions (i.e., mitochondrial activity, eicosanoid production) remains elusive, and characterizing these changes will be the focal point of this study. Our results indicate that the differentiation affected the proliferation of PLB-985 cells, without inducing apoptosis. A significant decrease in mitochondrial respiration was observed in differentiated PLB-985 cells. However, the overall mitochondria content was not affected. Immunoblotting with mitochondrial antibodies revealed a strong modulation of the succinate dehydrogenase A, superoxide dismutase 2, ubiquinol-cytochrome c reductase core protein 2 and ATP synthase subunit α in differentiated PLB-985 cells. Finally, eicosanoids (leukotriene B4, 12-hydroxyheptadecatrienoic and 15-hydroxyeicosatetraenoic acids) production was significantly increased in differentiated cells. In summary, our data demonstrate that the differentiation process of PLB-985 cells does not impact their viability despite a reduced respiratory state of the cells. This process is also accompanied by modulation of the inflammatory state of the cell. Of importance, our data suggest that PLB-985 cells could be suitable in vitro candidates to study mitochondrial-related dysfunctions in inflammatory diseases.