Asthma is a worldwide health problem. Activated T cells (ATCs) in the lung, particularly T helper 2 cells (Th2), are strongly associated with inducing airway inflammatory responses and chemoattraction of inflammatory cells in asthma. Small interfering RNA (siRNA) as a promising anti-sense molecule can specifically silence inflammation related genes in ATCs, however, lack of safe and efficient siRNA delivery systems limits the application of siRNA as a therapeutic molecule in asthma. Here, we designed a novel pulmonary delivery system of siRNA, transferrin-polyethylenimine (Tf-PEI), to selectively deliver siRNA to ATCs in the lung. Tf-PEI polyplexes demonstrated optimal physicochemical properties such as size, distribution, zeta-potential, and siRNA condensation efficiency. Moreover, in vitro studies showed significantly enhanced cellular uptake and gene knockdown mediated by Tf-PEI polyplexes in human primary ATCs. Biodistribution of polyplexes in a murine asthmatic model confirmed that Tf-PEI polyplexes can efficiently and selectively deliver siRNA to ATCs. In conclusion, the present work proves the feasibility to target ATCs in asthma via Tf receptor. This strategy could potentially be used to design an efficient siRNA delivery system for asthma therapy.

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In this study, we investigated whether activated T cells (ATC) armed with bispecific antibodies (aATC) can inhibits tumor growth and MDSC development in a Th1 cytokine–enriched (IL-2 and IFN-γ) microenvironment. Cytotoxicity mediated by aATC was significantly higher (P <0.001) against breast cancer cell lines in the presence of Th1 cytokines as compared with control co-cultures. In the presence of aATC, CD33+/CD11b+/CD14−/HLA-DR−MDSC population was reduced significantly under both control (P <0.03) and Th1-enriched (P <0.036) culture conditions. Cytokine analysis in the culture supernatants showed high levels of MDSC suppressive chemokines CXCL9 and CXCL10 in Th1-enriched culture supernatants with highly significant increase (P <0.001) in the presence of aATC. Interestingly, MDSC recovered from co-cultures without aATC showed potent ability to suppress activated T-cell-mediated cytotoxicity (P <0.001), IFN-γ production (P <0.01) and T-cell proliferation (P <0.05) compared to those recovered from aATC-containing co-cultures. These data suggest that aATC can mediate enhanced killing of tumor cells and may suppress MDSC and Treg differentiation, and presence of Th1 cytokines potentiates aATC-induced suppression of MDSC, sug-gesting that Th1-enriching immunotherapy may be benefi-cial in cancer treatment.