Pathogens and commensals: War and Peace at mucosal surface Nothing - - PowerPoint PPT Presentation

Philippe J Sansonetti & collaborators

Royal Society, London New Fellows Seminar July 9-10, 2014

Nothing in biology makes sense except in the light of evolution Theodosius Dobzhansky

Pathogens and commensals: War and Peace at mucosal surface

Symbionts

Innate immunity Physiological inflammation Surveillance/Tolerance Recognition network: PRRs:TLRs,NLRs, Rig1, MDA5…

Pathogens

Innate immunity Pathological inflammation Microbe & tissue destruction Amplification loop: TREM, HMGB1, Gal3, Sepsis, Septic shock Regulation Loss of control

Sansonetti, 2004, Nature Rev. Immunol. Sansonetti, 2006, Nat. Immunol. Sansonetti & Di Santo, 2007, Immunity Sansonetti & Medzhitov, 2009, Cell Sansonetti, 2010, Mucosal Immunology

Rupture of homeostasis = IBD,

• besity, diabetes, cancer ?

Adaptive immunity Pathogens recognition, capture, completion of eradication process, protection

Co-evolution has created an « immunological conundrum » that forces to conjugate tolerance to commensal bacteria and quick and efficient recognition and elimination of bacterial pathogens.

1012/ml in colon

How does one identify a harmful pathogen hidden amidst a herd of harmless symbionts ?

Bacterial life at mucosal surfaces

« Seating on a volcano »

O2, NO, ROS Antimicrobial peptides Lysozyme, proteases, lectins, phospholipases Transmigrating phagocytes sIgA Epithelium Mucus Cationic antimicrobial peptide hBD3 Sperandio et al.

Kim et al., PNAS, 2005 Arbibe et al., Nature Immunol., 2007 Sperandio et al., J. Exp. Med., 2008 Marteyn et al., Nature, 2010 Konradt et al., Cell Host Microbe, 2011 Puhar et al., Immunity, 2013

Symbionts/commensals: survive at distance or in particular niches, escape (regulate) innate defenses Pathogens: engage epithelium and subvert immune defenses

• Blocking of danger signaling
• Post-translational modification of

key immune signaling molecules

OCTN2 PepT1 QSM (hsl) MDP TLR NLR

Regulatory cascade

?

Regulatory genes

Mucus layer Regulatory cytokines, chemokines Antimicrobial molecules Epithelial apex Microbiota

Increase in ratio Treg/Th1, Th17 lymphocytes Increase in ratio Immature/mature DC and MΦ

Peace: symbiotic bacteria maintain gut homeostatic mechanisms

SYMBIONTS

Absence (limitation) of virulence factors PAMPs less agonist ? Sequestration, weak activity

• f TLRs

Life in biofilms on mucus surface (at distance of epithelium) Controled diffusion and sampling of PAMPs and prokaryotic signalisation molecules

Symbionts

Pro-inflammatory cascade

TLR

Pro-inflammatory genes

PMN Activated DC & MΦ Th1 / Th17 Pro-inflammatory cytokines, chemokines PMN

DC

K+ K+ NLRs

Caspase-1 activation IL-1β Muropeptides Flagellin

PATHOGENS

1 – Mucinases Eradication

• f

microbiota (niche occupancy) Adhesins / Invasins Secretory systems /effectors Hemolysins Massive engagement of PRRs Pathogenic properties sensed as exogenous danger signals 2 - Release of endogenous danger signals (DAMPs /small molecules) before initiation of proinflammatory transcriptional reprogramming. 3 – Subversion / dampening of innate (inflammatory) and adaptive immune responses

War: pathogenic bacteria disrupt / by-pass gut homeostatic mechanisms

Epithelial cells mucus

Basolateral macropinocytosis (TTSS) Vacuole lysis (TTSS) Escape to autophagy Motility, cell to cell spread (TTSS) IcsA

? ?

M cell MΦ B Lympho MΦ pyroptosis TTSS/IpaB

• Pyroptosis = proinflammatory apoptosis
• Activation of caspase-1, Release of IL-1β and IL-18

DC «facilitated translocation» Follicle-associated epithelium PNN Nod1 PGN NF-κB JNK TTSS Pro-inflammatory genes IL-8, other cytokines chemokines

• Development of inflammation
• Rupture of epithelial barrier
• Facilitation of invasion
• Stimulation of epithelial bactericidal

capacities Defensins and other bactericidal molecules CCL-20 B Lympho T Lympho

Pathogenesis of Shigella infection: central role

• f Type Three Secretory Apparatus (T3SA)

NOD LRRs CARD NOD LRRs CARD CARD

TLRs

NOD1 NOD2 IRAK TRAF6 RICK/Rip2

IkB IkB

P P

IkB IkB

P P

U U U U

MEKK3 IKK complex

IkB

PGN

PAMPs

Inflammatory programing based on sensing abnormal localisation of bacterial cell wall fragments and transcription of innate immunity genes

JNK Caspase-9

Girardin et coll., EMBO Reports, 2001 Girardin et coll.., Science, 2003 Girardin et coll., J.Biol.Chem., 2003

Epithelial cells

Muramyl-tri/tetrapeptide Muramyl-dipeptide

Inflammation

Pro-inflammatory genes Tri-Tetra-DAP/Nod1 MDP/Nod2

Shigella - danger signaling 1: cytosolic sensing of PGN by Nod molecules

Pyd

HSP90

Pyd NBD

SGT1

LRR NLRP3 NBD NLRP3 Caspase NBD NBD NAIP5 NLRC4/IPAF Pro-caspase-1 NLRC4/IPAF inflammasome NLRP3 inflammasome Caspase-1 Pro-IL1β Pro-IL18 IL1β IL18

Apoptosis

?

P2X7 Pannexin-1 (K+) K+ Bacterial hemolysins IpaB IpaC Uric acid cristals TTSS translocator ATP Flagellin

S.typhimurium P.aeruginosa

Flagellin

L..pneumophila

?

S.flexneri

IL1β IL18

S.aureus L.monocytogenes A.hydrophyla

Nigericin Maitotoxin K+

Zychlinsky et al., 1992, Nature Zychlinsky et al., 1994, J Clin Invest Hilbi H et al., 1998, J Biol Chem

Macrophages

Shigella

• danger signaling 2:

pyroptosis inflammasome

Rapid inflammatory programing based on release of a presynthetized pool of pro-inflammatory cytokines (Il-1β β β β, IL-18)

Inflammation

Inflammasome activation Differentiation of naive T cells to Th17 cells

HEMICHANNEL (Connexins)

x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x dx d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d

Tran Van Nhieu et al., 2003, Nat Cell Biol Puhar et al., 2013, Immunity

Shigella - danger signal 3: early epithelial cell release of ATP across connexin-based hemichannels (Danger-associated molecular patterns)

Rapid inflammatory programing based on release

• f intracellular

ATP (DAMPs) = Inflammasome activation = Th17 lymphocytes differentiation

Inflammation

VirB

ipaA, ipaB, ipaC, ipaD, ipgB1, ipgD, icsB,

• spC2/3/4,
• spD1, ospD2
• spD3, ospE1/2,
• spG,

ipaH1/2, ipaH4, ipaH7, ipaH9.8

MxiE

Expression, regulation, subversive function of T3SA effectors

before secretion after TTSS activation (target cell recognition)

INVASION MODULATION OF INNATE RESPONSES

IpaB, IpaC, IpaA, IpgB1,VirA, IpgD IpgD: phosphatidyl-inositol phosphatase, hydrolyses P in 4 in Pi(4,5)P2 (Niebuhr et al, 2002, Pendaries et al, 2006 EMBO J.). Anti-inflammatory +++ (Puhar et al., in review). OspG: kinase,binds/blocks ubiquitin transfer protein E2, protects I-kB from degradation. Anti-inflammatory +++ (Kim et al., 2005, PNAS). OspF: dephosphorylation of Erk1/2, epigenetic regulation of pro-inflammatory genes - i.e. IL-8. Regulates transmigration

• f PMNs through epithelium (Arbibe et al., 2007,Nat.Immunol.).

Phosphothreonine lyase (Li et al., 2007, Science). IpaHs: (5 + 5 chromosomal copies): New family of Ubiquitin ligases (E3) (Rohde et al., 2007, Cell Host & Microbes) IpaH9.8 targets NEMO (Ashida et al., 2010, Nat.Cell Biol.)

OTHER PHENOTYPES

IcsB: inhibion or autophagy (Ogawa et al., 2005, Science) VirA: inhibition of microtubules, facilitates actin-based motility (Yoshida et al., 2006, Science)

• spB
• spF
• spC1

virA

INHIBITION OF SECRETION

IpaB:(Mounier et al.,2012. Cell Host & Microbe)

HEMICHANNEL (Connexins)

x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d x d

IpgD

Pi(4,5)P2 Pi(5)P IpgD

Pi(5)P

Shigella T3SA effector IpgD dampens ATP-mediated danger signaling

Niebuhr et al., Mol. Micro. 2000 Niebuhr et al., EMBO J. 2002 Pendaries et al., EMBO J 2006

Inflammation x d x dx d x d x d x d

ATP release in luminal fluid, rabbit ileal loop. 4h infection Puhar et al., 2013, Immunity

wt S. flexneri) IpgD-

Histopathology, HES Rabbit ileal loop 8 h infection

IpgD

cellules épithéliales mucus macropinocytose baso-latérale (TTSS) lyse vacuole (TTSS) motilité/passage cellule-cellule (TTSS) IcsA M cell MΦ Lympho B MΦ pyroptosis TTSS/IpaB

• activation of caspase-1
• pyroptosis = pro-

inflammatory apoptosis

• release of IL-1β et IL-18

DC «facilitated translocation» follicle-associated epithelium Nod1 PGN NF-κB JNK TTSS Osp(s) TTSS IL-8 CCL-20 PNN

Suppression of humoral defense mechanisms Suppression of cellular defense mechanisms

AMPs

Kim et al. 2005. PNAS Arbibe et al. 2007. Nat Immunol Sperandio et al.2008. J Exp Med Bergounioux et al. 2012. Cell Host Microbe Sperandio et al. 2013. Infect Immun Puhar et al. 2013. Immunity, ATP

ATP

Suppression of danger signaling PR

ATP

ATP

Immunosuppressive environment induced by Shigella (innate)

Laurence Arbibe Stéphane Girardin Benoît Marteyn F-Xavier Campbell-Valois Maria Mavris Joëlle Mounier Claude Parsot Armelle Phalipon Thierry Pédron Andrea Puhar John Rohde Brice Sperandio Pamela Schnupf REST OF THE WORLD Guy Tran Van Nhieu et al. (INSERM, Coll. de France)Laurent Combettes (INSERM, Orsay) Bernard Payrastre et al. (INSERM, Toulouse) Chris Tang (University of Oxford) Philippe Jay (INSERM, IGF, Montpellier) Françoise Poirier et al. (Institut Jacques Monod, Paris) Sylvie Robine et al. (Institut Curie, Paris) Dana Philpott Marie-C. Prévost Jean-Yves Coppée Christian Muchardt Jost Enninga Nathalie Sauvonnet