Immunomodulatory effects of poly(I:C)-stimulated exosomes derived from chicken macrophages

Production, Isolation, and Detection of Poly IC in Extracellular Vesicles from U937 Cells

Double-stranded RNA is produced by viruses during their replicative cycle. It is a potent immune modulator and indicator of viral infection within the body. Extracellular vesicles (EVs) are lipid-bound particles released from cells homeostatically. Recent studies have shown that a commercially available dsRNA, poly inosinic: poly cytidylic acid (poly IC), can be detected within EVs. This finding opens the door for studying EVs as (1) carriers for dsRNA and (2) indicators of viral infection. To study dsRNA-containing EVs, we must have reliable methods for producing, isolating, and detecting them. This chapter uses U937, a pro-monocytic, human myeloid leukemia cell line, as the EV producer following poly IC treatment, and an immunoblot using an anti-dsRNA antibody (J2) for detection. Two methods for isolating the EVs and two methods for isolating the RNA from these EVs are described. Together, these methods effectively produce, isolate, and detect long dsRNA from EVs.

Progress towards Adjuvant Development: Focus on Antiviral Therapy

In recent decades, vaccines have been extraordinary resources to prevent pathogen diffusion and cancer. Even if they can be formed by a single antigen, the addition of one or more adjuvants represents the key to enhance the response of the immune signal to the antigen, thus accelerating and increasing the duration and the potency of the protective effect. Their use is of particular importance for vulnerable populations, such as the elderly or immunocompromised people. Despite their importance, only in the last forty years has the search for novel adjuvants increased, with the discovery of novel classes of immune potentiators and immunomodulators. Due to the complexity of the cascades involved in immune signal activation, their mechanism of action remains poorly understood, even if significant discovery has been recently made thanks to recombinant technology and metabolomics. This review focuses on the classes of adjuvants under research, recent mechanism of action studies, as well as nanodelivery systems and novel classes of adjuvants that can be chemically manipulated to create novel small molecule adjuvants.

Comparative analysis of exosomal miRNAs derived from lipopolysaccharide and polyinosinic-polycytidylic acid -stimulated chicken macrophage cell line

Exosomes play important roles in cellular communication by delivering exosomal proteins and nucleic acid molecules to cells. In particular, exosomal miRNAs can modulate various biological processes in recipient cells by repressing target gene expression. In this study, to identify the composition of exosomal miRNAs and their regulatory mechanisms against bacterial and viral infections, profiles of exosomal miRNAs from lipopolysaccharide (LPS) and polyinosinic-polycytidylic acid (poly(I:C))-stimulated chicken macrophage cell line (HD11) were analyzed by small RNA sequencing. Exosomes were purified after stimulation with LPS (1 μg/mL) and poly(I:C) (50 μg/mL) for 24 h. Then, exosomal RNA were analyzed for small RNA sequencing using the HiSeq 2500 System. Thirty six differentially expressed miRNAs (DE miRNAs) were obtained by comparing LPS-stimulated exosomes (LPS-EXO) and unstimulated exosomes (CTRL-EXO), 42 DE miRNAs in poly(I:C)-stimulated exosomes (POLY-EXO) and CTRL-EXO, and 45 DE miRNAs in LPS-EXO and POLY-EXO. Target genes of DE miRNAs were predicted using miRDB and TargetScan. KEGG pathway analysis showed that most of the target genes were related to mitogen-activated protein kinase and Wnt signaling pathways. Moreover, results of qRT-PCR for miRNAs (gga-miR-142-3p, gga-miR-19a-3p, gga-miR-21-3p, gga-miR-301a-3p, gga-miR-338-3p, and gga-miR-3523) were consistent with the sequencing results. This study will provide knowledge about immuno-regulatory mechanisms of exosomal miRNAs derived from macrophages against pathological insults such as bacterial and viral infections.

Functional genome-wide short hairpin RNA library screening identifies key molecules for extracellular vesicle secretion from microglia

Activated microglia release extracellular vesicles (EVs) as modulators of brain homeostasis and innate immunity. However, the molecules critical for regulating EV production from microglia are poorly understood. Here we establish a murine microglial cell model to monitor EV secretion by measuring the fluorescence signal of tdTomato, which is linked to tetraspanin CD63. Stimulation of tdTomato⁺ cells with ATP induces rapid secretion of EVs and a reduction in cellular tdTomato intensity, reflecting EV secretion. We generate a GFP⁺ tdTomato⁺ cell library expressing TurboGFP and barcoded short hairpin RNAs for genome-wide screening using next-generation sequencing. We identify Mcfd2, Sepp1, and Sdc1 as critical regulators of ATP-induced EV secretion from murine microglia. Small interfering RNA (siRNA-based) silencing of each of these genes suppresses lipopolysaccharide- and ATP-induced inflammasome activation, as determined by interleukin-1β release from primary cultured murine microglia. These molecules are critical for microglial EV secretion and are potential therapeutic targets for neuroinflammatory disorders.

Ruan et al. report genome-wide shRNA library screening on a tdTomato-CD63⁺ microglia cell model to identify factors implicated in the process of extracellular vesicle (EV) release. The molecules Sepp1, Mcfd2, and Sdc1 are critical for ATP-induced secretion of EV and EV-associated interleukin-1β from murine microglia.

Characterization of the Role of Extracellular Vesicles Released from Chicken Tracheal Cells in the Antiviral Responses against Avian Influenza Virus

During viral respiratory infections, the innate antiviral response engages a complex network of cells and coordinates the secretion of key antiviral factors, such as cytokines, which requires high levels of regulation and communication. Extracellular vesicles (EVs) are particles released from cells that contain an array of biomolecules, including lipids, proteins, and RNAs. The contents of EVs can be influenced by viral infections and may play a role in the regulation of antiviral responses. We hypothesized that the contents of EVs released from chicken tracheal cells are influenced by viral infection and that these EVs regulate the function of other immune cells, such as macrophages. To this end, we characterized the protein profile of EVs during avian influenza virus (AIV) infection and evaluated the impact of EV stimulation on chicken macrophage functions. A total of 140 differentially expressed proteins were identified upon stimulation with various stimuli. These proteins were shown to be involved in immune responses and cell signaling pathways. In addition, we demonstrated that EVs can activate macrophages. These results suggest that EVs play a role in the induction and modulation of antiviral responses during viral respiratory infections in chickens.

Investigating the growth performance, meat quality, immune function and proteomic profiles of plasmal exosomes in Lactobacillus plantarum-treated broilers with immunological stress

Exosomes are extracellular membranous nanovesicles that carry functional molecules to mediate cell-to-cell communication. To date, whether probiotics improve the immune function of broilers by plasmal exosome cargo is unclear. In this study, 300 broilers were allocated to three treatments: control diet (CON group), control diet + dexamethasone injection (DEX group), and control diet containing 1 × 10⁸ cfu g^-1 P8 + DEX injection (P8 + DEX group). The growth performance, meat quality and immune function of plasma and jejunal mucosa were detected. Exosomes were isolated from the plasma and characterized. Then, the exosome protein profile was determined by proteomic analysis. Correlation analyses between the exosomal proteins and growth performance, meat quality, immune function were performed. Lastly, the related protein levels were verified by multiple reaction monitoring (MRM). Results showed that P8 treatment increased the growth performance, meat quality and immune function of DEX-induced broilers with immunological stress. Moreover, the average diameters, cup-shaped morphology and expressed exosomal proteins confirmed that the isolated extracellular vesicles were exosomes. A total of 784 proteins were identified in the exosomes; among which, 126 differentially expressed proteins (DEPs) were found between the DEX and CON groups and 102 DEPs were found between the P8 + DEX and DEX groups. Gene ontology analysis indicated that DEPs between the DEX and CON groups are mainly involved in the metabolic process, cellular anatomical entity, cytoplasm, etc. DEPs between the P8 + DEX and DEX groups are mainly involved in the multicellular organismal process, response to stimulus, cytoplasm, etc. Pathway analysis revealed that most of the DEPs between the DEX and CON groups participated in the ECM-receptor interaction, focal adhesion, regulation of actin cytoskeleton, etc. Most of the DEPs between the P8 + DEX and DEX groups participated in the ErbB and PPAR signaling pathways. Moreover, many DEPs were correlated with the altered parameters of growth performance, meat quality and immunity in P8-treated broilers. MRM further revealed that the upregulated FABP6 and EPCAM in the DEX group were decreased by P8 + DEX treatment, and the downregulated C1QTNF3 in the DEX group was increased by P8 + DEX treatment. In conclusion, our findings demonstrated that P8 may promote the immune function, growth performance and meat quality of broilers with immunological stress by regulating the plasma exosomal proteins, especially the proteins of FABP6, EPCAM and C1QTNF3 and the pathway of PPAR (ILK/FABP6).