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Liposome-induced immunosuppression and tumor growth is mediated by macrophages and mitigated by liposome-encapsulated alendronate.

ABSTRACT: Liposomal nanoparticles are the most commonly used drug nano-delivery platforms. However, recent reports show that certain pegylated liposomal nanoparticles (PLNs) and polymeric nanoparticles have the potential to enhance tumor growth and inhibit antitumor immunity in murine cancer models. We sought herein to identify the mechanisms and determine whether PLN-associated immunosuppression and tumor growth can be reversed using alendronate, an immune modulatory drug. By conducting in vivo and ex vivo experiments with the immunocompetent TC-1 murine tumor model, we found that macrophages were the primary cells that internalized PLN in the tumor microenvironment and that PLN-induced tumor growth was dependent on macrophages. Treatment with PLN increased immunosuppression as evidenced by increased expression of arginase-1 in CD11b+Gr1+ cells, diminished M1 functionality in macrophages, and globally suppressed T-cell cytokine production. Encapsulating alendronate in PLN reversed these effects on myeloid cells and shifted the profile of multi-cytokine producing T-cells towards an IFN?+ perforin+ response, suggesting increased cytotoxic functionality. Importantly, we also found that PLN-encapsulated alendronate (PLN-alen), but not free alendronate, abrogated PLN-induced tumor growth and increased progression-free survival. In summary, we have identified a novel mechanism of PLN-induced tumor growth through macrophage polarization and immunosuppression that can be targeted and inactivated to improve the anticancer efficacy of PLN-delivered drugs. Importantly, we also determined that PLN-alen not only reversed protumoral effects of the PLN carrier, but also had moderate antitumor activity. Our findings strongly support the inclusion of immune-responsive tumor models and in-depth immune functional studies in the preclinical drug development paradigm for cancer nanomedicines, and the further development of chemo-immunotherapy strategies to co-deliver alendronate and chemotherapy for the treatment of cancer.

SUBMITTER: Rajan R

PROVIDER: S-EPMC5880305 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature

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Liposome-induced immunosuppression and tumor growth is mediated by macrophages and mitigated by liposome-encapsulated alendronate.

Rajan Robin R Sabnani Manoj K MK Mavinkurve Vikram V Shmeeda Hilary H Mansouri Hossein H Bonkoungou Sandrine S Le Alexander D AD Wood Laurence M LM Gabizon Alberto A AA La-Beck Ninh M NM

Journal of controlled release : official journal of the Controlled Release Society 20171223

Liposomal nanoparticles are the most commonly used drug nano-delivery platforms. However, recent reports show that certain pegylated liposomal nanoparticles (PLNs) and polymeric nanoparticles have the potential to enhance tumor growth and inhibit antitumor immunity in murine cancer models. We sought herein to identify the mechanisms and determine whether PLN-associated immunosuppression and tumor growth can be reversed using alendronate, an immune modulatory drug. By conducting in vivo and ex vi ...[more]

PMID: 29277680

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Project description:Background: We have previously shown that alendronate, an amino-bisphosphonate, when reformulated in liposomes, can significantly enhance the efficacy of cytotoxic chemotherapies and help remodel the immunosuppressive tumor microenvironment towards an immune-permissive milieu resulting in increased anticancer efficacy. In addition, we have previously shown that the strong metal-chelating properties of alendronate can be exploited for nuclear imaging of liposomal biodistribution. To further improve anticancer efficacy, a pegylated liposome formulation co-encapsulating alendronate and doxorubicin (PLAD) has been developed. In this study, we examined the effects of PLAD on the tumor immunologic milieu in a mouse fibrosarcoma model in which the tumor microenvironment is heavily infiltrated with tumor-associated macrophages (TAM) that are associated with poor prognosis and treatment resistance. Methods: Doxorubicin biodistribution, characterization of the tumor immunologic milieu, cellular doxorubicin uptake, and tumor growth studies were performed in Balb/c mice bearing subcutaneously implanted WEHI-164 fibrosarcoma cells treated intravenously with PLAD, pegylated liposomal doxorubicin (PLD), free doxorubicin, or vehicle. Results: PLAD delivery resulted in a high level of tumor doxorubicin that was 20 to 30-fold greater than in free doxorubicin treated mice, and non-significantly higher than in PLD treated mice. PLAD also resulted in increased uptake in spleen and slightly lower plasma levels as compared to PLD. Importantly, our results showed that PLAD, and to a lesser extent PLD, shifted cellular drug uptake to TAM and to monocytic myeloid-derived suppressor cells (MDSC), while there was no drug uptake in neutrophilic MDSC or lymphoid cells. Free doxorubicin cellular drug uptake was below detectable levels. PLAD, and to a lesser extent PLD, also induced significant changes in number and functionality of tumor-infiltrating TAM, MDSC, Treg, NKT, and NK cells that are consistent with enhanced antitumor immune responses in the tumor microenvironment. In contrast, free doxorubicin induced moderate changes in the tumor microenvironment that could promote (decreased Treg) or be detrimental to antitumor immune responses (decreased M1 TAM and NK cells). These immune modulatory effects are reflected in the therapeutic study which showed that PLAD and PLD inhibited tumor growth and significantly prolonged survival, while free doxorubicin showed little or no anticancer activity. Conclusion: We show that liposomal delivery of doxorubicin not only alters pharmacokinetics, but also dramatically changes the immune modulatory activity of the drug cargo. In addition, our data support that the PLAD nanotheranostic platform further enhances some immune changes that may act in synergy with its cytotoxic chemotherapy effects.

Project description:Background and purposeSystemic glucocorticoid therapy may effectively attenuate lung inflammation but also induce severe side-effects. Delivery of glucocorticoids by liposomes could therefore be beneficial. We investigated if liposome-encapsulated dexamethasone inhibited ventilator-induced lung inflammation. Furthermore, we evaluated whether targeting of cellular Fcγ-receptors (FcγRs) by conjugating immunoglobulin G (IgG) to liposomes, would improve the efficacy of dexamethasone-liposomes in attenuating granulocyte infiltration, one of the hallmarks of lung inflammation.Experimental approachMice were anaesthetized, tracheotomized and mechanically ventilated for 5 h with either 'low' tidal volumes ∼7.5 mL·kg(-1) (LV(T) ) or 'high' tidal volumes ∼15 mL·kg(-1) (HV(T) ). At initiation of ventilation, we intravenously administered dexamethasone encapsulated in liposomes (Dex-liposomes), dexamethasone encapsulated in IgG-modified liposomes (IgG-Dex-liposomes) or free dexamethasone. Non-ventilated mice served as controls.Key resultsDex-liposomes attenuated granulocyte infiltration and IL-6 mRNA expression after LV(T) -ventilation, but not after HV(T) -ventilation. Dex-liposomes also down-regulated mRNA expression of IL-1β and KC, but not of CCL2 (MCP-1) in lungs of LV(T) and HV(T) -ventilated mice. Importantly, IgG-Dex-liposomes inhibited granulocyte influx caused by either LV(T) or HV(T) -ventilation. IgG-Dex-liposomes diminished IL-1β and KC mRNA expression in both ventilation groups, and IL-6 and CCL2 mRNA expression in the LV(T) -ventilated group. Free dexamethasone prevented granulocyte influx and inflammatory mediator expression induced by LV(T) or HV(T) -ventilation.Conclusions and implicationsFcγR-targeted IgG-Dex-liposomes are pharmacologically more effective than Dex-liposomes particularly in inhibiting pulmonary granulocyte infiltration. IgG-Dex-liposomes inhibited most parameters of ventilator-induced lung inflammation as effectively as free dexamethasone, with the advantage that liposome-encapsulated dexamethasone will be released locally in the lung thereby preventing systemic side-effects.

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Liposome-induced immunosuppression and tumor growth is mediated by macrophages and mitigated by liposome-encapsulated alendronate.

Publications

Liposome-induced immunosuppression and tumor growth is mediated by macrophages and mitigated by liposome-encapsulated alendronate.

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