A recombinant heavy chain antibody approach blocks ART2 mediated deletion of an iNKT cell population that upon activation inhibits autoimmune diabetes

J Autoimmun. 2010 Mar;34(2):145-54. doi: 10.1016/j.jaut.2009.08.012. Epub 2009 Oct 1.

Abstract

The ectoenzyme ADP-ribosyltransferase 2.2 (ART2.2) can apoptotically delete various T-cell subsets. Depending on the involved apoptotic T-cell subset, enhanced ART2.2 activity could result in immunosuppression or autoimmunity. Diminished activity of the CD38 ectoenzyme that normally represents a counter-regulatory competitor for the NAD substrate represents one mechanism enhancing ART2.2 activity. Hence, it would be desirable to develop an agent that efficiently blocks ART2.2 activity in vivo. While the llama derived recombinant s+16 single domain antibody overcame the difficulty of specifically targeting the ART2.2 catalytic site potential therapeutic use of this reagent is limited due to short in vivo persistence. Thus, we tested if a modified version of s+16 incorporating the murine IgG1 Fc tail (s+16Fc) mediated long-term efficient in vivo suppression of ART2.2. We reasoned an ideal model to test the s+16Fc reagent were NOD mice in which genetic ablation of CD38 results in an ART2.2 mediated reduction in already sub-normal numbers of immunoregulatory natural killer T-(NKT) cells to a level that no longer allows them when activated by the super-agonist alpha-galactosylceramide (alpha-GalCer) to elicit effects inhibiting autoimmune type 1 diabetes (T1D) development. Treatment with s+16Fc efficiently mediated long-term in vivo inhibition of ART2.2 activity in NOD.CD38(null) mice, restoring their iNKT cell numbers to levels that upon alpha-GalCer activation were capable of inhibiting T1D development.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADP Ribose Transferases / genetics
  • ADP Ribose Transferases / immunology
  • ADP Ribose Transferases / metabolism*
  • ADP-ribosyl Cyclase 1 / genetics
  • ADP-ribosyl Cyclase 1 / immunology
  • ADP-ribosyl Cyclase 1 / metabolism
  • Animals
  • Diabetes Mellitus, Type 1 / immunology*
  • Diabetes Mellitus, Type 1 / therapy
  • Female
  • Galactosylceramides / immunology
  • Immunoglobulin Heavy Chains / administration & dosage*
  • Immunosuppression Therapy
  • Lymphocyte Activation / drug effects
  • Lymphocyte Activation / genetics
  • Lymphocyte Depletion
  • Mice
  • Mice, Knockout
  • Mice, Transgenic
  • Natural Killer T-Cells / drug effects
  • Natural Killer T-Cells / immunology
  • Natural Killer T-Cells / metabolism*
  • Natural Killer T-Cells / pathology
  • Protein Engineering
  • Recombinant Fusion Proteins / administration & dosage*
  • T-Lymphocytes, Regulatory / drug effects
  • T-Lymphocytes, Regulatory / immunology

Substances

  • Galactosylceramides
  • Immunoglobulin Heavy Chains
  • Recombinant Fusion Proteins
  • alpha-galactosylceramide
  • ADP Ribose Transferases
  • Art2b protein, mouse
  • ADP-ribosyl Cyclase 1