Alpha-Actinin:Renal Pathogenicity of anti-DNA Antibodies

  • Putterman, Chaim (PI)

Project: Research project

Project Details

Description

DESCRIPTION (provided by applicant): Antibodies against double stranded (ds)
DNA are a characteristic serologic hallmark of SLE. While it has been
demonstrated that anti-dsDNA antibodies play a critical role in the
pathogenesis of lupus nephritis, the mechanisms of injury are incompletely
understood. Experimental evidence strongly suggests that at least some
anti-dsDNA antibodies are pathogenic by virtue of their direct cross-reactivity
with renal antigen. We recently demonstrated that a pathogenic anti-dsDNA
antibody (R4A) binds to a 100 kD protein expressed on the cell surface of a
mesangial cell line derived from a lupus-prone MRL-lpr/lpr mouse, and that
DNAse treatment of the lysate does not affect binding. Binding was greatly
diminished in lysates of a mesangial cell line derived from a non-autoimmune
mouse, suggesting that antigen expression and/or availability at the level of
the target organ may be a factor in determining susceptibility to lupus
nephritis. Following identification of the 100 kD protein bound by R4A as
alpha-actinin, the binding of R4A to alpha-actinin was confirmed by Western
blot, ELISA, and inhibition studies. High titers of anti-alpha-actinin
antibodies were found in the serum and kidney eluates of lupus mice with
nephritis, and in the serum of lupus patients.
The goals of this proposal are to study if cross-reactivity with alpha-actinin
may be an important determinant of the renal pathogenicity of some anti-DNA
antibodies, and if the expression of alpha-actinin is genetically regulated and
modulated by gender and exposure to cytokines. We will determine if
anti-alpha-actinin antibodies are pathogenic and if they cross-react with
dsDNA, by immunization of mice with alpha-actinin and studying the
anti-alpha-actinin antibody response in normal and autoimmune mice. The
molecular basis for the differential levels of antigen display of alpha-actinin
between autoimmune and non-autoimmune mouse strains will be studied, and the
effects of age, gender, and cytokines known to be present in lupus kidneys on
alpha-actinin expression and antibody binding will be determined. Finally, we
will identify the epitopes of alpha-actinin that are recognized by pathogenic
anti-dsDNA antibodies to understand the generation of anti-alpha-actinin
antibodies, and determine the potential of alpha-actinin peptides in the
treatment of acute lupus nephritis.
StatusFinished
Effective start/end date7/12/026/30/15

ASJC

  • Medicine(all)