Exosomes in Allergic Airway Diseases.

PURPOSE OF REVIEW: This review will cover what is known regarding exosomes and allergy, and furthermore discuss novel mechanism of exosome-mediated immune modulation and metabolic regulation via the transfer of mitochondria. RECENT FINDINGS: Exosomes are nano-sized extracellular vesicles (EVs) derived from the endosome that play a direct role in governing physiological and pathological conditions by transferring bioactive cargo such as proteins, enzymes, nucleic acids (miRNA, mRNA, DNA), and metabolites. Recent evidence suggest that exosomes may signal in autocrine but, most importantly, in paracrine and endocrine manner, being taken up by neighboring cells or carried to distant sites. Exosomes also mediate immunogenic responses, such as antigen presentation and inflammation. In asthma and allergy, exosomes facilitate cross-talk between immune and epithelial cells, and drive site-specific inflammation through the generation of pro-inflammatory mediators like leukotrienes. Recent studies suggest that myeloid cell-generated exosomes transfer mitochondria to lymphocytes. Exosomes are nano-sized mediators of the immune system which can modulate responses through antigen presentation, and the transfer of pro- and anti-inflammatory mediators. In addition to conventional mechanisms of immune modulation, exosomes may act as a novel courier of functional mitochondria that is capable of modulating the recipient cells bioenergetics, resulting in altered cellular responses. The transfer of mitochondria and modulation of bioenergetics may result in immune activation or dampening depending on the context.

Exosomes in immunoregulation of chronic lung diseases.

Exosomes are nano-sized, membrane-bound vesicles released from cells that transport cargo including DNA, RNA, and proteins, between cells as a form of intercellular communication. In addition to their role in intercellular communication, exosomes are beginning to be appreciated as agents of immunoregulation that can modulate antigen presentation, immune activation, suppression, and surveillance. This article summarizes how these multifaceted functions of exosomes may promote development and/or progression of chronic inflammatory lung diseases including asthma, chronic obstructive pulmonary disease, and pulmonary fibrosis. The potential of exosomes as a novel therapeutic is also discussed.

Refractory asthma: mechanisms, targets, and therapy.

Asthma is a common medical condition affecting 300 million people worldwide. Airway inflammation, smooth muscle bronchoconstriction leading to airflow obstruction, and mucous hypersecretion are clinical hallmarks of asthma. The NHLBI Expert Panel Report 3 recommends inhaled corticosteroids (ICS) for patients with moderate to severe persistent asthma. Inhaled corticosteroids (ICS) target gene transcription through their interactions with the glucocorticoid (GC) receptor (GR) at the glucocorticoid response element (GRE). The GC/GR complex enhances anti-inflammatory but inhibits pro-inflammatory mediator production. Classically, asthma has been described as a Th2-associated eosinophil-predominant disease, but recently alternative models have been described including a Th17-mediated neutrophil-predominant phenotype resulting in patients with more severe disease who may be less responsive to steroids. Additional mechanisms of steroid resistance include increased activity of GR phosphorylating kinases which modify the interactions of GR with transcription factors to inhibit the ability of GR to bind with GRE, leading to an increase in pro-inflammatory gene transcription. Oxidative stress also affects the balance between pro-inflammatory and anti-inflammatory gene transcription through the modification of transcription factors and cofactors (such as PI3K) leading to the inhibition of histone deacetylase 2. Continued investigations into the mechanisms behind glucocorticoid resistance will lead to novel treatments that improve control of severe refractory asthma.

A myeloid cell-binding adenovirus efficiently targets gene transfer to the lung and escapes liver tropism.

Specific and efficient gene delivery to the lung has been hampered by liver sequestration of adenovirus serotype 5 (Ad5) vectors. The complexity of Ad5 liver tropism has largely been unraveled, permitting improved efficacy of Ad5 gene delivery. However, Kupffer cell (KC) scavenging and elimination of Ad5 still represent major obstacles to lung gene delivery strategies. KC uptake substantially reduces bioavailability of Ad5 for target tissues and compensatory dose escalation leads to acute hepatotoxicity and a potent innate immune response. Here, we report a novel lung-targeting strategy through redirection of Ad5 binding to the concentrated leukocyte pool within the pulmonary microvasculature. We demonstrate that this leukocyte-binding approach retargets Ad5 specifically to lung endothelial cells and prevents KC uptake and hepatocyte transduction, resulting in 165,000-fold enhanced lung targeting, compared with Ad5. In addition, myeloid cell-specific binding is preserved in single-cell lung suspensions and only Ad.MBP-coated myeloid cells achieved efficient endothelial cell transduction ex vivo. These findings demonstrate that KC sequestration of Ad5 can be prevented through more efficient uptake of virions in target tissues and suggest that endothelial transduction is achieved by leukocyte-mediated 'hand-off' of Ad.

Gene therapy and ovarian cancer: a review.

OBJECTIVE: To provide the obstetrician-gynecologist with the basic concepts of gene therapy, an overview of cancer gene therapy treatment strategies, and a summary of currently approved human gene therapy protocols for ovarian carcinoma. DATA SOURCES: A computerized search of articles published through December 1995 was performed on the MEDLINE data base. Additional sources were identified through cross-referencing. METHODS OF STUDY SELECTION: All identified references were reviewed with particular attention to their relevance to gene therapy for ovarian cancer. TABULATION, INTEGRATION, AND RESULTS: Each reference was reviewed to determine the relevant contribution to the fundamental science of gene therapy. Particular attention was paid to those studies that offered a rational strategy that might contribute to therapy for ovarian malignancy. CONCLUSION: Advances in molecular biology, immunology, and virology have enabled the concept of gene therapy for neoplastic disorders to become a reality. Given the lack of effective conventional therapy, those patients with recurrent or refractory ovarian cancer should be considered for currently approved investigational gene therapy protocols.

Novel gene therapy strategy to accomplish growth factor modulation induces enhanced tumor cell chemosensitivity.

erbB-2 is a cell surface transmembrane glycoprotein which, when overexpressed, has been shown to be relevant to intrinsic tumor cell chemoresistance. Thus, strategies to down-regulate cell surface erbB-2 have resulted in enhanced tumor cell chemosensitivity. We have recently reported a gene therapy strategy to down-modulate erbB-2 expression using a plasmid construct encoding an intracellular single chain antibody. Therefore, we now demonstrate enhanced chemosensitivity to cis-diamminedichloroplatinum in erbB-2 overexpressing tumor cells and a model system of stable clones using an intracellular single chain antibody. These findings are consistent with the hypothesis that erbB-2 plays a role in tumor cell chemoresistance. In addition, these findings represent a novel gene therapy approach to overcome erbB-2-mediated tumor cell chemoresistance.