PD-L1– and calcitriol-dependent liposomal antigen-specific regulation of systemic inflammatory autoimmune disease
Ryan Galea, Hendrik J. Nel, Meghna Talekar, Xiao Liu, Joshua D. Ooi, Megan Huynh, Sara Hadjigol, Kate J. Robson, Yi Tian Ting, Suzanne Cole, Karyn Cochlin, Shannon Hitchcock, Bijun Zeng, Suman Yekollu, Martine Boks, Natalie Goh, Helen Roberts, Jamie Rossjohn, Hugh H. Reid, Ben J. Boyd, Ravi Malaviya, David J. Shealy, Daniel G. Baker, Loui Madakamutil, A. Richard Kitching, Brendan J. O’Sullivan, Ranjeny Thomas
Ryan Galea, Hendrik J. Nel, Meghna Talekar, Xiao Liu, Joshua D. Ooi, Megan Huynh, Sara Hadjigol, Kate J. Robson, Yi Tian Ting, Suzanne Cole, Karyn Cochlin, Shannon Hitchcock, Bijun Zeng, Suman Yekollu, Martine Boks, Natalie Goh, Helen Roberts, Jamie Rossjohn, Hugh H. Reid, Ben J. Boyd, Ravi Malaviya, David J. Shealy, Daniel G. Baker, Loui Madakamutil, A. Richard Kitching, Brendan J. O’Sullivan, Ranjeny Thomas
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Research Article Nephrology

PD-L1– and calcitriol-dependent liposomal antigen-specific regulation of systemic inflammatory autoimmune disease

Abstract

Autoimmune diseases resulting from MHC class II–restricted autoantigen-specific T cell immunity include the systemic inflammatory autoimmune conditions rheumatoid arthritis and vasculitis. While currently treated with broad-acting immunosuppressive drugs, a preferable strategy is to regulate antigen-specific effector T cells (Teffs) to restore tolerance by exploiting DC antigen presentation. We targeted draining lymph node (dLN) phagocytic DCs using liposomes encapsulating 1α,25-dihydroxyvitamin D3 (calcitriol) and antigenic peptide to elucidate mechanisms of tolerance used by DCs and responding T cells under resting and immunized conditions. PD-L1 expression was upregulated in dLNs of immunized relative to naive mice. Subcutaneous administration of liposomes encapsulating OVA323–339 and calcitriol targeted dLN PD-L1hi DCs of immunized mice and reduced their MHC class II expression. OVA323–339/calcitriol liposomes suppressed expansion, differentiation, and function of Teffs and induced Foxp3+ and IL-10+ peripheral Tregs in an antigen-specific manner, which was dependent on PD-L1. Peptide/calcitriol liposomes modulated CD40 expression by human DCs and promoted Treg induction in vitro. Liposomes encapsulating calcitriol and disease-associated peptides suppressed the severity of rheumatoid arthritis and Goodpasture’s vasculitis models with suppression of antigen-specific memory T cell differentiation and function. Accordingly, peptide/calcitriol liposomes leverage DC PD-L1 for antigen-specific T cell regulation and induce antigen-specific tolerance in inflammatory autoimmune diseases.

Authors

Ryan Galea, Hendrik J. Nel, Meghna Talekar, Xiao Liu, Joshua D. Ooi, Megan Huynh, Sara Hadjigol, Kate J. Robson, Yi Tian Ting, Suzanne Cole, Karyn Cochlin, Shannon Hitchcock, Bijun Zeng, Suman Yekollu, Martine Boks, Natalie Goh, Helen Roberts, Jamie Rossjohn, Hugh H. Reid, Ben J. Boyd, Ravi Malaviya, David J. Shealy, Daniel G. Baker, Loui Madakamutil, A. Richard Kitching, Brendan J. O’Sullivan, Ranjeny Thomas

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Figure 6

Calcitriol liposomes modulate human DC phenotype and function.

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Calcitriol liposomes modulate human DC phenotype and function. (A) Human...
(A) Human PBMCs were stimulated for 18 hours with 10 μg/ml CpG in the absence or presence of varying dilutions of blank liposomes, liposomes encapsulating 400 ng/ml calcitriol and 40 μg/ml OVA323–339, or equivalent final concentrations of free calcitriol. TNF, IL-6, IL-10, and IFN-α concentrations were measured in supernatants. Representative of 2 experiments. *P < 0.05, **P < 0.01, ***P < 0.001, ANOVA at highest calcitriol concentration. The percentage of dead cells was <0.3% for all conditions at highest final calcitriol concentration. (B) Monocyte-derived DCs generated from 3 healthy human PB donors were incubated without or with 0.05% (5 nM calcitriol final concentration) v/v DiD-labeled liposomes for 2 hours and washed, and then DiD fluorescence was analyzed by flow cytometry. (C) Liposome-treated DCs were incubated with 100 ng/ml lipopolysaccharide for 48 hours and then stained with HLA-DR, CD40, CD80, and CD86. *P < 0.05, ANOVA. (D) Liposome-treated DCs were incubated with allogeneic CD4+ T cells (ratio 1:10) for 7 days. The percentage of CD4+Foxp3+ allogeneic T cells identified by flow cytometry is plotted for each donor pair. *P < 0.05, paired t test.