Mechanisms of antagonism of HIVspecific CD4+ T cell responses BSRI

Transcription

1 Mechanisms of antagonism of HIVspecific CD4+ T cell responses BSRI

2 Problems Virus escape from immune recognition Antagonism of T cell responses

3 Peptide-MHC-TCR interaction

4 T cell antagonism Variants of a peptide recognized by a T cell can block recognition of the original peptide

5 Classes of peptides Alexander et al. J. Immunol 1993

6 CD4+ T cell antagonism Alexander et al., J Immunol 1993 DeMagistris et al., Cell 1992 Ostrov et al., J Immunol 1993 Racciopi et al., J Exp Med 1993

7 Mechanism of action of TCR antagonism No dominant negative signal in CD8+ T cells Dominant negative signal in CD4+ T cells De Magistris et al., Cell 1992 Daniels et al., J Immunol 1999 Stotz et al., J Exp Med 1999 Robertson et al., J Immunol 1999

8 Antagonism in HIV infection Antagonism of CTL response in HIV Antagonism of HIV Vaccine response Klenerman et al., Nature 1994 Kent et al., J Immunol 1997

9 T cell antagonism by a variant peptide shorter than the full length epitope

10 Viral peptide in HLA Binding Groove HLA Class II molecule HLA Class II molecule

11 Clone AC-01 Clone 1 AC-01 Clone 2 AC-25 Clone 3 161J Clone 4 CTS01 Clone 5 HLA restriction DQ5 DQ7 DR1 DR4 DQ7 Minimum epitope EEKAFSPEVIP ( ) EPRGSDIAGT ( ) PEVIPMSALSEGATP ( ) EVIPMFSALS ( ) VHAGPIAPG ( ) Norris et al., AIDS Res Hum Retrovirus 2004

12 SFC/million Net CPM OD (405) Shorter peptide PG13 not active IFN-γ Proliferation Serine esterase PP PG Concentration (μg/ml) Concentration (μm) Norris et al., Molecular Immunol. 2006

13 % inhibition Antagonism by shorter peptide PG PG13 Flu IFN-gamma Proliferation Esterase release Norris et al., Molecular Immunol. 2006

14 Why is the shorter peptide PG 13 an antagonist?

15 Tetramer staining Biotinylated MHC molecule Peptide SA-PE T cell Streptavidin coupled fluorochrome T cell receptor

16 PG 13 tetramer binds with less avidity than PP16 MFI PP16 TFR IP13 PG13 PG PG13 TFR TFR PG13 IP Tet concentration (μg/ml) Norris et al., Molecular Immunol. 2006

17 Does binding of shorter vs. longer peptide reveal function?

18 P1 P4 P6 P9

19

20 Zavala-Ruiz et al., PNAS 2004

21 Zavala-Ruiz et al., PNAS 2004

22 Glycine turn abolished GLY PRO Norris et al., Molecular Immunol. 2005

23 % inhibition Engineered antagonist peptide Flu PG P--- Norris et al., Molecular Immunol. 2005

24 Conclusions I Residues outside the MHC binding core can interact with and activate the T cell Partial T cell receptor engagement results in antagonism Antagonist peptide-mhc maintains ability to bind TCR with lower affinity than agonist

25 What gene pathways are disrupted after antagonist peptide exposure?

26 STAT signaling pathway

27 Activation truncated by antagonist Time (min) S T A T 3 S T A T 5

28 Activation truncated by antagonist

29 Multiplex detection of secreted cytokines Jacobs et al., Retrovirology 2014

30 Genes with 1.5 fold greater difference in expression between Ag and Ag+Ant B. B. Ag < Ag + Ant Ag< Ag+Ant *** *** C. Ag Ag> > Ag+Ant + Ant *** *** A. *** ** C. C. *** *** *** Jacobs et al., Retrovirology 2014

31 IPA Comparison of gene array data Yellow = Ag, Green = Ag + Ant, Predicted Activation Blue = Ant p-value Activation z-score Annotated Function State # Molecules activation of T lymphocytes 2.93E E E-09 Decreased differentiation of lymphocytes 1.67E E E expansion of T lymphocytes 3.65E E E proliferation of lymphocytes 3.88E E E proliferation of T lymphocytes 9.20E E E T cell homeostasis 3.94E E E function of T lymphocytes* 8.27E-17 Increased E stimulation of leukocytes* 4.53E-13 Increased E-05 Decreased stimulation of lymphocytes* 1.07E-14 Increased E-06 Decreased stimulation of T lymphocytes* 1.74E-14 Increased E-06 Decreased * These functions did not match to Ag + Ant condition with a significant p value. Jacobs et al., Retrovirology 2014

32 Ag Ag Ag Ag + Ant IPA Comparison of gene array data Jacobs et al., Retrovirology 2014

33 Gene expression profile of T cell stimulation matches that of SIV vaccine trial Fukazawa et al., Nat Med 2012 Jacobs et al., Retrovirology 2014

34 Conclusions II Antagonism results in aborted activation due to a dominant negative signal Link to existing vaccine study where Ag + Ant treatment showed similar profile to vaccine failure

35 Acknowledgments BSRI John Heitman Dale Hirschkorn Evan Jacobs Harvard Howell Moffett Margaret Clark Eric Rosenberg Bruce Walker University of Massachusetts Thomas Cameron Zarixia Zavala-Ruiz Jennifer Stone Larry Stern University of Toronto Des Persad Luoling Xu Longsi Ran David Kelvin