title: Poly(I:C) and CpG-ODN combined aerosolization to treat lung metastases and counter the immunosuppressive microenvironment.
abstract: The immunostimulatory ability of synthetic oligonucleotides containing CpG motifs (CpG-ODN), agonists of Toll-like receptor 9 (TLR9), can be harnessed to promote antitumor immunity by their application at the tumor site to stimulate local activation of innate immunity; however, particularly in the lung, tumor-associated immunosuppression can subvert such antitumor innate immune responses. To locally maintain continuous activation of innate subpopulations while inhibiting immunosuppressive cells, we evaluated aerosol delivery CpG-ODN combined with Poly(I:C), a TLR3 agonist able to convert tumor-supporting macrophages to tumoricidal effectors, in the treatment of B16 melanoma lung metastases in C57BL/6 mice. Aerosolization of CpG-ODN with Poly(I:C) into the bronchoalveolar space reduced the presence of M2-associated arginase- and IL-10-secreting macrophages in tumor-bearing lungs and increased the antitumor activity of aerosolized CpG-ODN alone against B16 lung metastases without apparent signs of toxicity or injury of the bronchial-bronchiolar structures and alveolar walls. Moreover, CpG-ODN/Poly(I:C) aerosol combined with dacarbazine, a therapeutic agent used in patients with inoperable metastatic melanoma able to exert immunostimulatory effects, led to a significant increase in antitumor activity as compared to treatments with aerosolized CpG-ODN/Poly(I:C) or dacarbazine alone. This effect was related to an enhanced recruitment and cytotoxic activity of tumor-infiltrating NK cells in the lung. Our results point to aerosol delivery as a convenient approach for repeated applications of immunostimulants in patients with lung metastases to maintain a continuous local activation of innate immune cells while suppressing polarization of tumor-infiltrating macrophages to an M2 phenotype.
authors.affiliation: Dipartimento di Scienze Biomediche per la Salute; Università degli Studi di Milano ; Milan, Italy.
authors.forename: Valentino
authors.initials: V
authors.lastname: Le Noci
authors.affiliation: Molecular Pharmacology Unit; Fondazione IRCCS Istituto Nazionale dei Tumori ; Milan, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Tortoreto
authors.affiliation: Dipartimento PRO.SA.MI; Unità di Immunologia dei Tumori; Universita degli Studi di Palermo ; Palermo, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Gulino
authors.affiliation: Molecular Targeting Unit; Fondazione IRCCS Istituto Nazionale dei Tumori ; Milan, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Storti
authors.affiliation: Dipartimento di Scienze Biomediche per la Salute; Università degli Studi di Milano ; Milan, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Bianchi
authors.affiliation: Molecular Pharmacology Unit; Fondazione IRCCS Istituto Nazionale dei Tumori ; Milan, Italy.
authors.forename: Nadia
authors.initials: N
authors.lastname: Zaffaroni
authors.affiliation: Dipartimento PRO.SA.MI; Unità di Immunologia dei Tumori; Universita degli Studi di Palermo ; Palermo, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Tripodo
authors.affiliation: Molecular Targeting Unit; Fondazione IRCCS Istituto Nazionale dei Tumori ; Milan, Italy.
authors.forename: Elda
authors.initials: E
authors.lastname: Tagliabue
authors.affiliation: Dipartimento di Scienze Biomediche per la Salute; Università degli Studi di Milano ; Milan, Italy ; Molecular Targeting Unit; Fondazione IRCCS Istituto Nazionale dei Tumori ; Milan, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Balsari
authors.affiliation: Dipartimento di Scienze Biomediche per la Salute; Università degli Studi di Milano ; Milan, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Sfondrini
keywords: TLR agonists; aerosol delivery; dacarbazin; lung metastases; mice