Transduction efficacy of bone marrow-derived versus pulmonary macrophages in mice with either lentiviral or adenoviral vectors encoding for GM-CSF

Introduction: Granulocyte macrophage-colony stimulating factor (GM-CSF) is a hematopoietic growth factor involved in the terminal differentiation and survival of alveolar macrophages with important implications for macrophage-dependent lung physiological responses as well as host protective immunity against pneumotropic bacteria (J Immunol 187: 5346, 2011).

Methods: We here performed a comparative analysis of murine bone marrow-derived monocyte (BMM) versus resident alveolar macrophage (rAM) transduction with either lentiviral or adenoviral vectors encoding for murine GM-CSF (LV-GM-CSF versus AdGM-CSF).

Results: Lentiviral (LV) transduction of BMM for 16 hours resulted in increased transgene and protein expression beginning at day 3 until day 28, accompanied by significantly improved survival of LV-GM-CSF- as compared to LV-eGFP-transduced BMM over time. In contrast, rAM demonstrated substantial cytotoxic cell death relative to BMM at 16h post LV transduction, while LV transduction of rAM for 2 hours resulted in efficient transgene expression starting at day 3 until day 15. Interestingly, transfection of rAM with AdGM-CSF did not cause any cytotoxicity, and resulted in peak transgene and protein expression on day 7 post-transfection along with improved survival of AdGM-CSF versus control vector exposed rAM. In contrast, transfection of BMM with AdGM-CSF resulted in a low transgene expression peaking on day 10 with a rapid decline thereafter and no improved survival compared to control vector exposed BMM.

Discussion: The data reveal different efficacy profiles of viral vector systems in terms of transgene expression, cytotoxicity, and cell survival in monocytic cells as compared to terminally differentiated alveolar macrophage populations with implications for adoptive cell transfer studies in lung bacterial infection models.

*Presenting author