Noncytotoxic Inhibition of the Immunoproteasome Regulates Human Immune Cells In Vitro and Suppresses Cutaneous Inflammation in the Mouse.

TitleNoncytotoxic Inhibition of the Immunoproteasome Regulates Human Immune Cells In Vitro and Suppresses Cutaneous Inflammation in the Mouse.
Publication TypeJournal Article
Year of Publication2021
AuthorsKioon MDominique, Pierides M, Pannellini T, Lin G, Nathan CF, Barrat FJ
JournalJ Immunol
Date Published2021 04 01
KeywordsAnimals, Cell Movement, Cells, Cultured, Cytotoxicity, Immunologic, Dendritic Cells, Disease Models, Animal, Female, Humans, Inflammation, Lupus Erythematosus, Cutaneous, Lymphocyte Activation, Macrophages, Mice, Mice, Inbred C57BL, Proteasome Endopeptidase Complex, Proteasome Inhibitors, Skin, T-Lymphocytes

Inhibitors of the immunoproteasome (i-20S) have shown promise in mouse models of autoimmune diseases and allograft rejection. In this study, we used a novel inhibitor of the immunoproteasome, PKS3053, that is reversible, noncovalent, tight-binding, and highly selective for the β5i subunit of the i-20S to evaluate the role that i-20S plays in regulating immune responses in vitro and in vivo. In contrast to irreversible, less-selective inhibitors, PKS3053 did not kill any of the primary human cell types tested, including plasmacytoid dendritic cells, conventional dendritic cells, macrophages, and T cells, all of which expressed genes encoding both the constitutive proteasome (c-20S) and i-20S. PKS3053 reduced TLR-dependent activation of plasmacytoid dendritic cells, decreasing their maturation and IFN-α response and reducing their ability to activate allogenic T cells. In addition, PKS3053 reduced T cell proliferation directly and inhibited TLR-mediated activation of conventional dendritic cells and macrophages. In a mouse model of skin injury that shares some features of cutaneous lupus erythematosus, blocking i-20S decreased inflammation, cellular infiltration, and tissue damage. We conclude that the immunoproteasome is involved in the activation of innate and adaptive immune cells, that their activation can be suppressed with an i-20S inhibitor without killing them, and that selective inhibition of β5i holds promise as a potential therapy for inflammatory skin diseases such as psoriasis, cutaneous lupus erythematosus, and systemic sclerosis.

Alternate JournalJ Immunol
PubMed ID33674446
PubMed Central IDPMC7987762
Grant ListR01 AI132447 / AI / NIAID NIH HHS / United States
R01 AI143714 / AI / NIAID NIH HHS / United States
UL1 TR002384 / TR / NCATS NIH HHS / United States
Related Faculty: 
Tania Pannellini, M.D., Ph.D.

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