Influence of Apoptotic Bodies and Apoptotic Microvesicles on NO Production in Macrophages

Apoptotic bodies: bioactive treasure left behind by the dying cells with robust diagnostic and therapeutic application potentials

Apoptosis, a form of programmed cell death, is essential for growth and tissue homeostasis. Apoptotic bodies (ApoBDs) are a form of extracellular vesicles (EVs) released by dying cells in the last stage of apoptosis and were previously regarded as debris of dead cells. Recent studies unraveled that ApoBDs are not cell debris but the bioactive treasure left behind by the dying cells with an important role in intercellular communications related to human health and various diseases. Defective clearance of ApoBDs and infected-cells-derived ApoBDs are possible etiology of some diseases. Therefore, it is necessary to explore the function and mechanism of the action of ApoBDs in different physiological and pathological conditions. Recent advances in ApoBDs have elucidated the immunomodulatory, virus removal, vascular protection, tissue regenerative, and disease diagnostic potential of ApoBDs. Moreover, ApoBDs can be used as drug carriers enhancing drug stability, cellular uptake, and targeted therapy efficacy. These reports from the literature indicate that ApoBDs hold promising potential for diagnosis, prognosis, and treatment of various diseases, including cancer, systemic inflammatory diseases, cardiovascular diseases, and tissue regeneration. This review summarizes the recent advances in ApoBDs-related research and discusses the role of ApoBDs in health and diseases as well as the challenges and prospects of ApoBDs-based diagnostic and therapeutic applications.

Circulating extracellular vesicles and rheumatoid arthritis: a proteomic analysis

Circulating extracellular vesicles (EVs) are membrane-bound nanoparticles secreted by most cells for intracellular communication and transportation of biomolecules. EVs carry proteins, lipids, nucleic acids, and receptors that are involved in human physiology and pathology. EV cargo is variable and highly related to the type and state of the cellular origin. Three subtypes of EVs have been identified: exosomes, microvesicles, and apoptotic bodies. Exosomes are the smallest and the most well-studied class of EVs that regulate different biological processes and participate in several diseases, such as cancers and autoimmune diseases. Proteomic analysis of exosomes succeeded in profiling numerous types of proteins involved in disease development and prognosis. In rheumatoid arthritis (RA), exosomes revealed a potential function in joint inflammation. These EVs possess a unique function, as they can transfer specific autoantigens and mediators between distant cells. Current proteomic data demonstrated that exosomes could provide beneficial effects against autoimmunity and exert an immunosuppressive action, particularly in RA. Based on these observations, effective therapeutic strategies have been developed for arthritis and other inflammatory disorders.

Exosome: A New Player in Translational Nanomedicine

Summary: Exosomes are extracellular vesicles released by the vast majority of cell types both in vivo and ex vivo, upon the fusion of multivesicular bodies (MVBs) with the cellular plasma membrane. Two main functions have been attributed to exosomes: their capacity to transport proteins, lipids and nucleic acids between cells and organs, as well as their potential to act as natural intercellular communicators in normal biological processes and in pathologies. From a clinical perspective, the majority of applications use exosomes as biomarkers of disease. A new approach uses exosomes as biologically active carriers to provide a platform for the enhanced delivery of cargo in vivo. One of the major limitations in developing exosome-based therapies is the difficulty of producing sufficient amounts of safe and efficient exosomes. The identification of potential proteins involved in exosome biogenesis is expected to directly cause a deliberate increase in exosome production. In this review, we summarize the current state of knowledge regarding exosomes, with particular emphasis on their structural features, biosynthesis pathways, production techniques and potential clinical applications.

Downregulated Rac1 promotes apoptosis and inhibits the clearance of apoptotic cells in airway epithelial cells, which may be associated with airway hyper-responsiveness in asthma

The accumulation of airway apoptotic cells may be an important factor causing airway hyper-responsiveness (AHR). Whether the apoptotic cells can be promptly removed is related to the occurrence and course of asthma. In recent years, studies have shown that Rac1 is involved in many cellular biological activities including the formation and elimination of apoptotic cells. In this study, based on the analysis of airway local cells and related factors in asthmatic mice, we evaluated the expression of Rac1 in airway epithelial cells or phagocytes and analysed its relationship with the incidence of apoptosis or scavenging of apoptotic cells. Our data showed that the expression level of Rac1 in asthmatic mice decreased significantly, while the expression of IL-33 increased obviously. The airway epithelial cell line was stimulated by curcumin at 50 μmol/L for 24-48 hours; more than 50% of the cells were apoptotic, and of which, about 20% were late apoptosis. Rac1 inhibitor (NSC23766) can enhance the apoptosis effect. In addition, the ability of phagocytosis and migration in the epithelial cells or macrophages was increased following the application of Rac1 inhibitors or specific siRNA in a dose-dependent manner, and the expression level of IL-33 was simultaneously increased after blocking Rac1. It is suggested that the down regulation of Rac1 in asthma may contribute to the apoptosis of airway epithelial cells and affect the clearance of apoptotic cells, which will lead to the aggregation of the apoptotic cells in the respiratory tract and participate in AHR.