Ligand-competent fractalkine receptor is expressed on exosomes.

Expression of chemokine receptor CX3CR1 is reportedly restricted to several cell types including natural killer cells, cytotoxic T cells, monocytes, and macrophages. However, its expression and function on exosomes, which are nanosized extracellular vesicles known to act as mediators of intercellular communications, remain unclear. Here, we investigated CX3CR1 expression on exosomes isolated from various cell types. Although we found that all the exosomes tested in our study highly expressed CX3CR1, this chemokine receptor was expressed only inside, but barely on, their source cells. Moreover, exosomal CX3CR1 was capable of binding soluble CX3CL1. Therefore, our study suggests that CX3CR1 is a novel and ligand-competent exosome receptor.

In vitro antioxidant, anti-inflammatory, cytotoxic activities against prostate cancer of extracts from Hibiscus sabdariffa leaves.

BACKGROUND: Hibiscus sabdariffa (HS) leaves are a vegetable, which is used as a healthy sour soup for protection against chronic diseases in Thai traditional medicine. OBJECTIVES: To investigate antioxidant, anti-inflammatory and cytotoxic activities of Hibiscus sabdariffa leave extracts from diferent extraction methods. MATERIAL AND METHOD: Fresh and dry Hibiscus sabdariffa leaves were extracted by various methods such as maceration with 95% and 50% ethanol, squeeze, and boiling with water or decoction. All extracts were testedfor antioxidant activity by using DPPH radical scavenging assay, anti-inflammatory activity by determination on inhibitory effect of nitric oxide production on RAW264. 7 cell. Cytotoxic activity also tested against human prostate cancer cell line (PC-3) by using sulforhodamine B (SRB) assay. Total phenolic content determined by the Folin-Ciocalteu colorimetric method. RESULTS: The results found that the 95% ethanolic extract of Hibiscus sabdariffa dried leaves (HSDE95) showed the highest antioxidant activity with an EC50 of 34.51±2.62 µg/ml and had the highest phenolic content (57.00±3.73 mg GAE/g). HSDE95 also showed potent cytotoxicity against prostate cancer cell line with an IC50 of 8.58±0.68 µg/ml whereas HSDE95 and all of extracts ofHibiscus sabdariffa leaves had no anti-inflammatory activity. CONCLUSION: The obtained results revealed that HSDE95 extract showedpotent cytotoxic activity against prostate cancer cells but low antioxidant and anti-inflammatory activities. This extract should be further isolated as active compounds against prostate cancer.