Felix Yarovinsky. Department of Immunology, UT Southwestern Medical Center. Innate immune defense to Toxoplasma gondii

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1 Felix Yarovinsky Department of Immunology, UT Southwestern Medical Center Innate immune defense to Toxoplasma gondii

2 Pathogen recognition by innate immune cells Pathogen Parasites Viruses Bacteria Initiator sensor cell (innate immune receptors) Protective immune response

3 Major questions in the Lab: What are the molecular mechanisms of innate recognition of parasites? How does innate recognition define host protection from infectious diseases?

4 The central role for TLR11 and MyD88 in IL-12 mediated immunity against T. gondii T. gondii TLR11 TLR2 IL-12 PROFILIN GPI Pattern recognition (pathogen-decoding) MyD88 NK CD4 Th1 innate CD8 Effector phase adaptive IFN-γ IFN-γ IFN-γ Intracellular killing

5 The mucosal immune system can initiate an immune response against T. gondii in the absence of TLR11 4 Systemic (IP) Infection 4 ORAL Infection IL-12p40 (ng/ml) <0.05 <0.05 IL-12p40 (ng/ml) < WT TLR11 -/- MyD88 -/- 0 WT TLR11 -/- MyD88 -/-

6 Visualization of IL-12-positive cells during T. gondii infection T. gondii Source of IL-12p40 (YFP) in vivo? Yet40 (IL-12p40-YFP) WT (Yet40) TLR11-/-x Yet40 villus Lamina propria Adapted from Ganz (2000), Nat. Immunol

7 Visualization of IL-12-positive cells during T. gondii infection WT TLR11-/- Lamina propria DC CD11c IL-12p40 WT TLR11 KO 3.07% 0.50% CD11c IL-12p40 % CD11c+IL-12p WT TLR11 KO

8 Identification of IL-12p40 producing cells in peripheral lymphoid organs during oral infection with T. gondii. WT TLR11 KO 10 CD11c 7.02% 2.29% CD11c % CD11c+IL-12p WT TLR11 KO IL-12p40 IL-12p40 mln, day 5 post infection

9 Natural route of the T. gondii infection results in TLR11-independent Th1 responses to the parasite 10 4 WT TLR11 KO MyD88 KO Peroral infection ORAL FL4-H: IFNg APC IFN-γ FL1-H: CD4 FITC CD4 FL4-H: IFNg APC FL1-H: CD4 FITC FL4-H: IFNg APC D 4 F LI T 1 - H 4 WT TLR11 KO MyD88 KO 4 4 Systemic infection FL4-H: IFNg APC IP IFN-γ CD F L 1 - H 1 4 FL4-H: IFNg APC D 4 F F I TL C1 - H D 4 FF I L T 1 C - H FL4-H: IFNg APC

10 Two possible models Mucosal DC directly recognize T. gondii through a TLR11-independent mechanism that governs IL-12 production The mucosal microbial environment is responsible for indirect stimulation of anti-parasitic responses T. gondii Commensal bacteria Small intestine, 10 8 bacteria/ml Intestine Epithelial cells DC

11 Can mucosal DC directly recognize T. gondii through a TLR11-independent mechanism? 3 IL-12p40 (ng/ml) Toxo WT - + TLR2 KO TLR4 KO TLR2x4 DKO TLR9 KO TLR11 KO Mucosal DC IL-12 responses in vitro depend on TLR11

12 Is the mucosal microbial environment responsible for indirect stimulation of anti-parasitic responses? (d-21) Antibiotic treatment (3 wks), (d0) Toxo, oral infection Plate bacteria d3 Analysis of IL-12 production CFU/g IL-12p40 (ng/ml) WT WT + antibiotics TLR11 KO TLR11 KO + antibiotics 0 WT WT TLR11 KO + antibiotics TLR11 KO + antibiotics Commensal bacteria are required for IL-12 production in response to T. gondii in the absence of TLR11

13 Commensal bacteria are essential for Th1 immunity during oral infection infection with T. gondii in the absence of TLR11 WT TLR11 KO Control IFN-γ IFN-γ CD4 Antibiotic treated IFN-γ IFN-γ CD4 CD4 CD4

14 Gut commensal bacteria direct a protective immune response against human pathogen Toxoplasma gondii T. gondii Commensal bacteria Small intestine, 10 8 bacteria/ml Intestine Epithelial cells DC T. gondii: invasion and tissue damage Micro flora: a molecular adjuvant

15 Gut commensal bacteria regulate a protective immune response against Toxoplasma gondii TOXO antibiotics Peroral infection (+/- Abx) Alicia Benson

16 Conclusions (1) A novel function for commensal bacteria: protection against pathogens - gut commensal bacteria function as a molecular adjuvant during parasitic infections, providing TLR-dependent immunostimulatory signals

17 Pathogen recognition by innate immune cells pathogen Toxoplasma Initiator sensor cell? Dendritic cell Epithelial cell Innate immune response Macrophage Monocyte Systemic infection Neutrophil Mast cell

18 Cell-specific MyD88-dependent regulation of immunity Mice with floxed Myd88 gene Deleter mice with cellspecific expression of Cre recombinase Mice with deletion of Myd88 gene in DC, T, epithelia cells, or macrophages and neutrophils X = CD11c-Cre (DC) Mlys-Cre (Mf) Lck-Cre (T) Villin-Cre (E) floxed Targeted allele loxp loxp Myd88 Baidong Hou

19 Role of MyD88 signaling in DCs for survival of mice upon T. gondii infection Low dose (40 cysts) High dose (200 cysts) Systemic infection Alicia Benson Baidong Hou

20 Role of MyD88 in DCs for the recruitment of inflammatory cells in acute T. gondii infection

21 Expansion and dissemination of T. gondii in the DC-Myd88 -/- mice PEC PEC (Day 5)

22 Role of MyD88 in DCs for the recruitment of inflammatory cells in acute T. gondii infection

23 Induction of IFN γ in the T. gondii-infected DC-Myd88 -/- mice

24 Induction of IFN γ in the T. gondii-infected DC-Myd88 -/- mice

25 The central role for IL-12 in IFN-γ mediated immunity against T. gondii T. gondii IL-12 NK IFN-γ Intracellular killing

26 CD11c +MHC II+ CD11b low-neg F4/80 - Ly6C - Defective IL-12 induction in T. gondii-infected DC-Myd88 -/- mice

27 Induction of IL-12 in the T. gondii-infected DC-Myd88 -/- mice PBS ril-12 (day 1)

28 IL-12 NK Mo Mo IFN-γ NK TLR (MyD88) DC NK Intracellular killing IFN-γ IL-12 NO Mo IFN-γ NK

29 Activation of T cells in the DC-Myd88 -/- mice

30 Acknowledgements Alicia Benson Carolyn Sturge Reed Pifer UCSF Baidong Hou Anthony DeFranco UTSW Medical Center Lora Hooper Michael Norgard The Endowed Scholars Program in Medical Science NIH/NIAID R01AI085263; R21AI079371