Abstract 12771: When Auto-Antibodies Potentiate: The Paradoxical Signalling Role of Anti-HSP27 Auto-Antibody Immune Complexes Improves Athero-Protection
Introduction: While we recently demonstrated that elevated serum levels of the Heat Shock Protein (HSP27) are athero-protective (JACC 2013), we are cognizant of the presence of anti-HSP27 auto-antibodies in human serum that, intuitively, might attenuate the salutary functions of this protein. Interestingly, we note higher levels of anti-HSP27 auto-antibodies in healthy controls compared to CAD patients.
Hypothesis: Taking an iconoclastic perspective, we posit that auto-antibodies to HSP27 function to enhance the athero-protective effects of HSP27.
Methods / Results: Briefly, we reassessed a number of the mechanistic published parameters of the athero-protective effects of HSP27 but now in the presence of anti-HSP27 auto-antibodies.
1) HSP27-auto-antibodies increases HSP27 particle size and quench its in vitro chaperone activity yet enhance the internalization of exogenously administered HSP27.
2) Compared to the same concentration of HSP27 without antibodies, the combination of HSP27 and its autoantibodies strengthens HSP27 binding to the surface of THP-1 MΦ cells and doubles NF-κB activation (alkaline phosphatase reporter assay, p<0.001)
3) In the presence of anti-HSP27 auto-antibodies Dil-Ox-LDL uptake is inhibited ~38% (p<0.01), secretion of the anti-inflammatory cytokine IL-10 is increased (p<0.0001) while secretion of the inflammatory cytokines IL-8 and IL-1β is attenuated (p<0.03, p<0.001 respectively) in THP-1 MΦ.
4) In vitro biochemical studies indicate that the interaction of HSP27 with pattern recognition receptors (TLR4, SR-AI and CD36) is strengthened by auto-antibody coupling to HSP27.
5) HEK cells containing a reporter construct for NF-kB activation and expressing TLR4, SR-AI or CD36 respectively, show enhanced NF-kB activation when treated with HSP27 in the presence of anti-HSP27 auto-antibodies (e.g., 67% increase, p<0.001 for HEK Blue TLR4 cells).
Conclusion: Anti-HSP27 auto-antibodies enhance the athero-protective effects of HSP27 by augmenting internalization of the protein, increasing NF-kB signalling and unexpectedly producing a less inflammatory cellular milieu. Hence, there is the potential to develop HSP27 immunization strategies for the prevention and/or treatment of atherosclerosis.
Author Disclosures: C. Shi: None. Y. Chen: None. Y. Li: None. E.R. O’Brien: None.
- © 2014 by American Heart Association, Inc.