Granzyme B is dispensable for immunologic tolerance to self in a murine model of systemic lupus erythematosus.

Published

Journal Article

OBJECTIVE: Proteolytic autoantigen cleavage by the serine protease granzyme B has been implicated in the development of systemic autoimmune disease; however, there has been no conclusive demonstration of a pathogenic role for granzyme B in autoimmunity. In this study, we evaluated the role of granzyme B in a murine model of autoimmunity. METHODS: To identify potential novel granzyme B substrates, complementary DNAs encoding nuclear factor 45 (NF45) and NF90 were used to generate (35)S-methionine-labeled proteins by coupled in vitro transcription/translation. Radiolabeled proteins were then incubated with purified recombinant granzyme B or caspases, and the cleavage products were analyzed by autoradiography. We also immunized granzyme B-deficient and granzyme B-intact mice with the mineral oil pristane. Production of autoantibodies directed against granzyme B substrates in response to pristane was evaluated by Western blotting, immunoprecipitation, and enzyme-linked immunosorbent assay. RESULTS: The double-stranded RNA-binding protein NF90 was identified as a novel substrate for caspases and granzyme B, both in vitro and in vivo. NF90 is uniquely cleaved by granzyme B in vitro; however, pristane immunization still induced anti-NF90 antibodies in granzyme B-deficient mice. Pristane-treated granzyme B-deficient mice also produced antibodies directed against the U1-70-kd antigen, a previously identified granzyme B substrate. Last, antibodies directed against U1-70 kd arose spontaneously in granzyme B-deficient mice. CONCLUSION: These results demonstrate that granzyme B is not required for the production of autoantibodies directed against antigens that are granzyme B substrates in vitro. The data also suggest a protective role for this proapoptotic protease in systemic autoimmunity.

Full Text

Duke Authors

Cited Authors

  • Graham, KL; Thibault, DL; Steinman, JB; Okeke, L; Kao, PN; Utz, PJ

Published Date

  • June 2005

Published In

Volume / Issue

  • 52 / 6

Start / End Page

  • 1684 - 1693

PubMed ID

  • 15934098

Pubmed Central ID

  • 15934098

International Standard Serial Number (ISSN)

  • 0004-3591

Digital Object Identifier (DOI)

  • 10.1002/art.21092

Language

  • eng

Conference Location

  • United States