APS-Aetiology Angela Tincani Dipartimento di Scienze Cliniche e - - PowerPoint PPT Presentation

INTERNATIONAL CONFERENCE ON PARADIGM CHANGES in the Management of Early Pregnancy and Pregnancy Loss (PCMEP) London, UK, February 21-24, 2019

APS-Aetiology

Pregnancy Loss: Sporadic and Recurrent

Angela Tincani

Dipartimento di Scienze Cliniche e Speriimentali Universita degli Studi di Brescia U.O. C Reumatologia e Immunologia Clinica Spedali Civili di Brescia

AGENDA

• Antiphospholipid Syndrome (APS) and

antiphospholipid antibodies (aPL)

• Animal models of Obstetric APS
• Pathogenesis of obstetric APS

ANTIPHOSPHOLIPID SYNDROME (APS)

CLINICAL CRITERIA

Myiakis, et al. JTH; 2006

CLASSIFICATION CRITERIA

• Vascular thrombosis (≥ 1 episode)
• Pregnancy morbidity:
• ≥ 3 early consecutive miscarriages (<10 w)
• ≥ 1 fetal death (> 10 w)
• ≥ 1 premature birth (< 34 w) due to pre-eclampsia/eclampsia/placental insufficiency

LABORATORY CRITERIA

• aCL (IgG/IgM) (med/high titre)
• Anti-b2GPI (IgG/IgM) (med/high titre)
• LAC

(at least one, confirmed 12 weeks apart)

1 CLINICAL CRITERIA + 1 LABORATORY CRITERIA

DIAGNOSTIC AND PATHOGENETIC ROLE!

Anti- b2GPI aCL LA

ANTIPHOSPHOLIPID SYNDROME (APS)

THE ANTIBODIES

β₂GLYCOPROTEIN I: PHYSIOLOGICAL FUNCTIONS

Meroni PL, et al. Lupus; 2016

It binds to negatively charged phospholipids such as CL Abundantly present in normal plasma Highly conserved among species during evolution β₂GPI deficient individuals are healthy β₂GPI deficient mice do not display a clear phenotype

BUT…

PHYSIOLOGICAL FUNCTIONS

V III II I

+ + + + Modified from Miyakis S, Thromb Res 2004; 114:335-46

• Natural Anticoagulant
• Scavenging protein

β₂GLYCOPROTEIN I

β₂GPI is the main target Ag ➪ β₂GPI-dependent aPL are pathogenic β₂GPI can be present on the surface of several cells: extravillous trophoblasts syncytiotrophoblasts decidual endothelial cells

β₂GLYCOPROTEIN I: DOMAINS and ANTIBODIES

Anti-D1 antibodies are a more specific marker for thrombosis and pregnancy morbidity Anti-D4/5 antibodies were described in non-thrombotic, non-autoimmune conditions

V III II I

+ + + +

β₂GPI is composed of FIVE “DOMAINS”: different subpopulations of anti-β₂GPI may carry a different pathogenic potential

Modified from Miyakis S, Thromb Res 2004; 114:335-46

Chighizzola C, et al. J Autoimm; 2017

In pregnant APS patients

AGENDA

• Antiphospholipid Syndrome (APS) and

antiphospholipid antibodies (aPL)

• Animal models of Obstetric APS
• Pathogenesis of obstetric APS

ANTIPHOSPHOLIPID SYNDROME (APS)

THE ANIMAL MODELS

Branch, et al. J Obstetr Gynecol; 1990. Blank, et al. PNAS; 1991. Piona, et al. Sc J Immunol; 1995

Pathogenetic role

• f aPL in

experimental models: no need of a 2° hit

Agostinis C, et al. Blood; 2011

ANTIPHOSPHOLIPID SYNDROME (APS)

THE ANIMAL MODELS

PREGNANT MICE: in vivo distribution

• f cyanine 5.5-

labeled β2GPI The uterine signal was localized at the implantation sites, but was undetectable on the fetuses Specific β2GPI signal in the liver & in the uterus

Agostinis C, et al. Blood; 2011

ANTIPHOSPHOLIPID SYNDROME (APS)

THE ANIMAL MODELS: Passive infusion models for aPL-mediated fetal loss

Meroni PL et al. Nat Rev Rheumatol; 2011 Holers, et al. J Immunol; 2002. Girardi, et al. JCI; 2003 Shoenfeld, et al. Eur J Clin Invest; 2001 Piona, et al. Sc J Immunol; 1994. Martinez, et al. PNAS; 2007

• One shot passive infusion of small amounts
• f aPL IgG after mating/ before implantation
• Repeated passive injection of large amounts
• f aPL IgG after implantation

AGENDA

• Antiphospholipid Syndrome (APS) and

antiphospholipid antibodies (aPL)

• Animal models of Obstetric APS
• Pathogenesis of obstetric APS

OBSTETRIC-APS: PATHOGENESIS

PLACENTAL THROMBOSIS IMPARIED SPIRAL ARTERY REMODELLING DEDIDUAL INFLAMMATION DECREASED TROPHBLAST PROLIFERATION AND DIFFERENTATION

histopathologic finding in the placentae of aPL-affected human pregnancies

Viall CA, et al. Autoimmun Rev; 2015

COMPLEMENT DEPOSITION

OBSTETRIC-APS: PATHOGENESIS

Viall CA, et al. Autoimmun Rev; 2015

Increased syncytial knots Decreased vasculosyncytial membranes Decidual inflammation Imparied spiral artery remodelling Placental infarction

PLACENTAL THROMBOSIS DEFECTIVE PLACENTATION FETAL SIDE MATERNAL SIDE

OBSTETRIC-APS: PATHOGENESIS

Rand JH, et al. Blood; 2010. Giannakopoulos B, et al. Blood; 2007. Krone KA, et al. Curr Rheumatol Rep; 2010. Yang, et al. Rheumatology; 2010

• Disruption of Annexin 5 shiel of the trophoblast and endothelial cell monolayers.
• Upregulation of Tissue Factor expression.
• Interaction with endothelial cells binding to β2GPI ➪ procoagulant and pro-inflammatory

endothelial state.

• Binding to Ag expressed on platelets ➪ platelet aggregation.
• Interference with plasma components of the coagulation cascade inhibiting anticoagulant

activity.

BUT… Placental thrombosis is NOT the main pathogenic pathway…

1) THROMBOSIS

Possible prothrombotic effects of aPL:

OBSTETRIC-APS: PATHOGENESIS

2) INFLAMMATION: CYTOKINES (1)

Fischetti F, et al. Blood; 2005. Pierangeli SS, et al. Ann Rheum Dis; 2007

⇧ IL-1β and IL-8

• aPL, via TLR-4 and MyD88, induce trophoblasts to secrete IL-1β and IL-8
• Downstream of MyD88 is mediated by uric acid which activates NLRP3 inflammasome
• Downstream of TLR-4 is mediated by microRNA-146a-3p

⇧ TNF𝛃

• TNF𝛃 is a key mediator of strong inflammation in aPL-induced pregnancy loss
• link between complement C5a-C5aR activation, pathogenic aPL and fetal damage

OBSTETRIC-APS: PATHOGENESIS

2) INFLAMMATION: CYTOKINES (2)

Fischetti F, et al. Blood; 2005. Pierangeli SS, et al. Ann Rheum Dis; 2007

⇩ IL-10

• Related to aPL-induced miscarriages, fetal losses, preterm birth

⇧ IFN𝛃

• Sensitizing maternal endothelium to the antiangiogenic effects of soluble Flt-1
• Inhibition of transcription of proangiogenic VEGF
• Vasculopathic effects of elevated IFNα in active SLE patients

OBSTETRIC-APS: PATHOGENESIS

3) COMPLEMENT ACTIVATION

Fischetti F, et al. Blood; 2005. Pierangeli SS, et al. Arthritis Rheum; 2007. Girardi G, et al. J Exp Med; 2006

• C3 activation is required for aPL-induced fetal loss
• C5a key effector: upregulation of tissue factor and neutrophils inflammation
• Increased levels of Bb and sC5b-9, complement activation products, early in pregnancy were

significantly associated with adverse pregnancy outcomes (APOs)

• Protective role of heparin because of anti-complement activity
• In mice, prevention of preeclampsia by inhibition of complement activation (animals deficient in

complement components or receptors or treated with complment inhibitors)

• Presence of low complement levels during the first trimester is an independent risk factor for fetal loss in

patients on conventional treatment (p = 0.02, OR 2.3, CI 95% 1.17–9.15)

Fredi M, e al Risk Factors for adverse Maternal and Fetal Outcomes in Women With confirmed aPl Positivity: results From a Multicenter study of 283 Pregnancies. Frontiers in Immunology, 2018.

OBSTETRIC-APS: PATHOGENESIS

3) COMPLEMENT ACTIVATION

Tedesco F, et al. Front Immunol; 2018

Complement deposition (C1q, C4d, C3b, C5b-9) was found in placenta tissue from women positive for aPL by immunoproxidase staining PLACENTAL VILLI PLACENTAL DECIDUA

OBSTETRIC-APS: PATHOGENESIS

4) DEFECTIVE PLACENTATION

D’Ippolito S, Meroni PL et al, Aut Rev 2014

• Inhibition of syncytiotrophoblast differentiation (reduced secretion of hCG)
• Impairment of trophoblast invasiveness (inhibition of expression/activity MMPs)
• Decrease in trophoblast expression of cadherins and integrins

FETAL SIDE

• Inhibition of endometrial angiogenesis both in vitro and in vivo (decreased VEGF)

MATERNAL SIDE

Hypoperfusion and ischemia/reperfusion injury ➪ pregnancy loss, PE, IUGR

OBSTETRIC-APS: PATHOGENESIS

4) DEFECTIVE PLACENTATION: aPL EFFECTS ON TROPHOBLASTS

Meroni PL et al, Nat Rev 2011

• During syncitium formation, phosphatidylserine is expressed

in the outer layer of the cell membrane

• β2GPI is expressed on the cell membrane (perhaps due to

binding to phosphatidylserine)

• Circulating anti-β2GPI antibodies bind β2GPI
• Antibodies induce cell membrane perturbation

INHIBITION OF PROLIFERATION AND INVASIVINESS INDUCTION OF APOPTOSIS

CONCLUSIONS:

• Decidual inflammation
• Imparied spiral artery remodelling
• Activation of complement system
• Inhibition of proliferation and invasiveness of

trophoblasts

• Antiphospholipid Antibodies (aPL) are both

diagnostic and pathogenetic for APS

• Animal models show aPL pathogenic role in fetal loss
• Placental thrombosis is not the main pathogenic

pathway of obstetric-APS, but different pathways concur:

Andrea Lojacono Sonia Zatti Francesca Ramazzotto Cristina Zanardini Obstetric Gynecology Mario Motta Neonatal Intensive Care Unit

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