CD11b activation suppresses TLR-dependent inflammation and autoimmunity in systemic lupus erythematosus

J Clin Invest. 2017 Apr 3;127(4):1271-1283. doi: 10.1172/JCI88442. Epub 2017 Mar 6.

Abstract

Genetic variations in the ITGAM gene (encoding CD11b) strongly associate with risk for systemic lupus erythematosus (SLE). Here we have shown that 3 nonsynonymous ITGAM variants that produce defective CD11b associate with elevated levels of type I interferon (IFN-I) in lupus, suggesting a direct link between reduced CD11b activity and the chronically increased inflammatory status in patients. Treatment with the small-molecule CD11b agonist LA1 led to partial integrin activation, reduced IFN-I responses in WT but not CD11b-deficient mice, and protected lupus-prone MRL/Lpr mice from end-organ injury. CD11b activation reduced TLR-dependent proinflammatory signaling in leukocytes and suppressed IFN-I signaling via an AKT/FOXO3/IFN regulatory factor 3/7 pathway. TLR-stimulated macrophages from CD11B SNP carriers showed increased basal expression of IFN regulatory factor 7 (IRF7) and IFN-β, as well as increased nuclear exclusion of FOXO3, which was suppressed by LA1-dependent activation of CD11b. This suggests that pharmacologic activation of CD11b could be a potential mechanism for developing SLE therapeutics.

MeSH terms

  • Animals
  • CD11b Antigen / genetics
  • CD11b Antigen / immunology*
  • Female
  • Forkhead Box Protein O3 / genetics
  • Forkhead Box Protein O3 / immunology
  • Humans
  • Interferon Regulatory Factor-3 / genetics
  • Interferon Regulatory Factor-3 / immunology
  • Interferon Regulatory Factor-7 / genetics
  • Interferon Regulatory Factor-7 / immunology
  • Interferon Type I / genetics
  • Interferon Type I / immunology
  • Lupus Erythematosus, Systemic / genetics
  • Lupus Erythematosus, Systemic / immunology*
  • Lupus Erythematosus, Systemic / pathology
  • Macrophages / immunology*
  • Macrophages / pathology
  • Male
  • Mice
  • Mice, Inbred MRL lpr
  • Polymorphism, Single Nucleotide
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / immunology
  • Toll-Like Receptors / genetics
  • Toll-Like Receptors / immunology*

Substances

  • CD11b Antigen
  • FOXO3 protein, human
  • Forkhead Box Protein O3
  • FoxO3 protein, mouse
  • IRF3 protein, human
  • IRF7 protein, human
  • ITGAM protein, human
  • Interferon Regulatory Factor-3
  • Interferon Regulatory Factor-7
  • Interferon Type I
  • Irf3 protein, mouse
  • Irf7 protein, mouse
  • Toll-Like Receptors
  • Proto-Oncogene Proteins c-akt