pathophysiologie des glomérulonéphrites...

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Pathophysiologie des glomérulonéphrites

extra-membraneuses

Pierre Ronco

Unité INSERM 1155

Service de Néphrologie

Hôpital Tenon

43ème Séminaire d'enseignement du CUEN

6 Juin 2016

Outline of the lecture

• Background and review of recent pathophysiologicaladvances

• From the bench to the bedside

- diagnostic tests

- predictive value of antibodies

- treatment monitoring

• Exogenous antigens

• Perspectives

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Membranous Nephropathy

Major cause of nephrotic syndrome and chronic renal failure

Aetiologies of membranous nephropathy

• 30% associated with

:- infections

- cancers

- autoimmune diseases

- drugs

• 70% « idiopathic forms »

Treatment is controversial because of unpredictable outcome vs

side-effects and lack of pathophysiology-driven therapy

•

• Proteinuria as the only biomarker for disease follow-up!

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Walter Heymann, Cleveland, 1959

Heymann nephritis

Renal BB IgG deposits Megalin, the target

antigen of HN

In situ formation of immune deposits

Podocytes

Endothelium

Rat: megalin

Human?

GBM

Proteinuria

Activation of

complement

Kerjaschki and Farquhar PNAS 1982, 79:5557 ; Ronco et al J Immunol 1986, 136:125

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The case : Hugo D. (male gender)

• 34 Wks of gestation : oligohydramnios and enlarged

kidneys

• 38 Wks : birth

• 1st Days of life : respiratory distress and oligoanuria,

followed by nephrotic range proteinuria and increased

blood pressure

• 4 Wks : CT-guided kidney biopsy

• Negative tests for syphilis, toxoplasmosis, cytomegalovirus

and hepatitis -B virus infections

• Negative Coombs’ test. Normal levels of complement

components at day 35

Debiec et al. N Engl J Med 2002, 346:2053

Antigen identification from an extreme phenotype :

Neonatal membranous nephropathy

IgG

Infant born with MN and nephrotic

syndromePLACENTA

C5b-9

MOTHER FETUS

Debiec et al. N Engl J Med. 2002, 346:2053

NEP

NEP

NEP

anti-NEP IgG

Blot: anti-NEP mAb

mother control1 2

83

175

1 2

Asymptomatic Transient nephrotic syndrome

NEP : neutral

endopeptidase

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III

A A C C T C T A CA A C T C T A C T

Wild-type

A

Wild-type Heterozygote

T C C G A G A A T C C G A G AA T C T G A G A

Heterozygote Homozygote

AA CC TC TAC A A C T C TAC T

7

15

Portugal Netherlands, Morocco,

Germany, Italy

466delCP156fsX169

1342C→TR448X

ATG TGA

7 153 2419exon

MME cDNA

Membranous nephropathy : a monogenic diseaseAll mothers have truncating mutations in MME gene

From antigen identification

to genetic defect

IgG

PLACENTA

anti-NEP IgG

MOTHER

NEP

NEPNEP deficient

FETUS

Genetic defect

Five families

Morocco Netherlands Portugal Germany Italy

Debiec et al. N Engl J Med 2002 and Lancet 2004

Y

GBM

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Auto-immune « idiopathic » MN in adults

Principle of pangenomic (GWAS) studies

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From polygenic disease

to rare association of common variants

556 Patients ; 2338 controls (Euro MN Consortium = F+UK+NL)

Stanescu et al, New Engl J Med, 2011, 364: 616 ; Coenen et al, J Am Soc Nephrol,

2013,24:677

PLA2R1

HLA-DQA1

No mutation

in PLA2R1

coding sequence

Risk of MN x 80

Are anti-PLA2R antibodies pathogenic?

• Transfer experiments impossible because of lack of expression

of PLA2R in mouse, rat and rabbit podocytes

• Lack of experimental model

• Strong predictive value of anti-PLA2R antibody

• Recurrence after transplantation : « The human model » of

passive Heymann nephritis

• Exceptional case of recurrence related to PLA2R IgG3k mAb

(Debiec et al, JASN 2012, 23:1949)

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Direct effect of autoantibodies :

The example of PLA2R

C

G1106S

M292V

H300D

Internalization

Degradation

ROS production and

activation of DNA-

damage pathways

MAPK activation

Lipid mediator

production

N 1 2 3 4 5 6 7 8

CRD FN2D CTLD

Positive regulator

Negative regulator

Extracellular domain

Conformation-dependent epitopes

TMD

CD

Putative PLA2

binding

domain

Debiec et al, Semin Immunopathol 2014, 36:381

A new podocyte antigen in adult patients with

MN : THSD7A

N 1 2 3 4 5 6 7 8

CRD FN2DCTLD

TMD

CDPutative PLA2

binding domainN 1

Conformational epitope is

located in this region

31 mer peptide from this domain

A

B

TMD

CDN

Trombospondin type-1 domains TSDs

1 2 3 4 5 6 7 8 9 10 11

RGD

motif

PLA2R

Thrombospondin type-1 domain containing 7A (THSD7A)

Kao et al, JASN 2014 ,

Sept 9 ;

Fresquet et al,

JASN 2014, Oct 6

Tomas et al, NEJM 2014,

371: 2277

10 % of PLA2R-negative patients with MN

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- diagnostic tests




• Perspectives

Hoxha E et al, NDT 2011, 26:2526

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Specificity and sensitivity of PLA2R antibody

Debiec ,Tesar and Ronco; Hofstra JASN 2012 ;

Hoxha et al, NDT 2011, KI 2012; Qin et al, JASN 2011

iMN SLE Cancer HBV GvH DC HC

N=689

70%

Po

siti

ve

fo

r a

nti

-PLA

2R

(%

)

100

75

50

25

N=71

2%

N=21

19%

N=19

15%

N=17

12%

N=90

0%

N=153

0%

« Secondary » MN

Meta-analysis (2014)

- 15 studies, 2212 patients

- Specificity = 99%

(95% CI : 96-100%)

- Sensitivity = 78%

(95% CI :66-87%)

Du et al, PLoSOne 2014, 9:e104936

Antigen detection in biopsy

is more sensitive than serology

Tenon cohort 2000-2014

- n = 106 (84 iMN ; 22 sMN)

- sensitivity PLA2R - Ag : 86%

- ‘’ aPLA2R-Ab : 76%

Pourcine et al, unpublished

Retrospective

diagnosis

Debiec and Ronco, New Engl J Med, 2011, 364 :689 ; Svobodova et al, NDT,

2013, 28:1839 ; Hofstra et al, J Am Soc Nephrol, 2012, 23:1735 ;

Ruggenenti et al, J Am Soc Nephrol, 2015, March 24

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There are exceptions…..

Secondary MN and PLA2R

Lupus MN HepB Sarcoidosis

Coincidence of iMN with the associated disease ?

Stehlé T et al, NDT 2015, 30:1047

IgG subclass distribution according

to underlying disease

IgG1 IgG2 IgG3 IgG4

Idiopathic + to +++ + + +++

Lupus +++ +++ ++ ±

Neoplasia +++ +++ + 0 to ++

Recurrent MN in the

allograft

++ ++ + +++

De novo MN in the

allograft

+++ ++ - +

Noël LH et al, Clin Immunol Immunopathol 1988, 46:186 ; Ohtani et al, NDT, 2004,

19:574 ; Qu et al, NDT 2012, 27:1931 ; Debiec, personal data ; Markowitz,

personal data

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Management of newly diagnosed MN

Newly diagnosed

Membranous nephropathy

1. Anti-PLA2R & PLA2R Antigen

in kidney biopsy

2. IgG subclasses in biopsy

3. N° inflam. cells per glomeruli

Antibody/Ag (-) OR IgG1-2

predominance OR > 8

inflammatory cells per glomeruli

Secondary MN

Search for cancer

Antibody/Ag (+) AND IgG4

predominance AND inflammatory

cells per glomeruli ≤ 8

Idiopathic MN

Stop investigation except if

personal and hereditary

cancer risk factors

Cambier J and Ronco P,

Clin JASN, 2012 7:1701

High levels of PLA2R-Ab are correlated with :

• A lower rate of remission, either spontaneous or

induced by IS treatment

• A higher risk :

- of occurrence of nephrotic syndrome in non-

nephrotic patients

- of renal function deterioration

• A longer time to remission under IS treatment

Kanigicherla D et al, Kidney Int 2013 83: 940 ;

Hofstra JM et al, JASN 2012 23: 1735 ; Hoxha E et al, JASN 2014 25:1357 ;

Ruggenenti P et al, JASN 2015, March 14; Hoxha E et al, PLoS One 2014 9:e110681

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Percent changes in proteinuria, serum

albumin and anti-PLA2R antibody levels

-100

-50

0

50

100

0 6 12 18 241 3 9

months

Anti PLA2R autoantibody

Y = -77.926+0.770*(X^-2-.975)-0.404*(X^3-1.038)

Time to 50% decrease = 0.65 months

24-h Proteinuria

Y = -46.89-99.379*(X^0.5-1.006)+24.376*(X-1.0125)

Time to 50% decrease = 10.5 months

Serum Albumin

Y = 45.91+ 19.810*(ln(X)-0.0124)+0.179*(X^3-1.038)

Time to 50% increase = 11.4 months

Me

an

pe

rce

nt

cha

ng

e v

s b

ase

lin

e

Y =mean percent change vs baseline

X = (time+1)/10

Ruggenenti, Debiec,…, Ronco, Remuzzi, J Am Soc Nephrol 2015 26:2545

13 13 13 12 11 10 9 8 6 4 2

31 31 27 26 24 16 16 12 12 11 10

0 6 12 18 24 30 36 42 48 54 60

months

0.00

0.25

0.50

0.75

1.00

0.00

0.25

0.50

0.75

1.00

10 10 10 9 8 8 8 8 6 4 2

31 31 27 26 24 16 16 12 12 11 10

0 6 12 18 24 30 36 42 48 54 60

Unadjusted HR (95%CI): 7.68 (2.04-28.91 ); p=0.003

Adjusted HR (95%CI): 6.70 (1.68-26.81); p=0.007

Increase YES

Increase NO

Patients at risk

Pro

po

rtio

n o

f p

ati

en

ts w

ith

re

lap

se

of

the

ne

ph

roti

c sy

nd

rom

e

Increase YES

Increase NO

Emergence YES

Emergence NO

Patients at risk

months

Unadjusted HR (95%CI): 7.03 (1.80-27.44 ); p=0.00

Adjusted HR (95%CI): 6.54 (1.57-27.14); p=0.010

Pro

po

rtio

n o

f p

ati

en

ts w

ith

re

lap

se

of

the

ne

ph

roti

c sy

nd

rom

e

Re-emergence YES

Re-emergence NO

PLA2R Ab titer increase or antibody re-emergence is

associated with a high risk of relapse

Ruggenenti, Debiec,…, Ronco, Remuzzi, J Am Soc Nephrol 2015 26:2545

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Anti-PLA2R antibodies predict

relapse rate after IS therapy

Bech et al, Clin JASN 2014, 9:1386

• Recurrent : about 50% anti-PLA2R

• De novo : 0

• In patients with a positive test at the time of TP there is

~80% chance of recurrence but 20% have not recurred

for up to 9 years (PPV=83%)

• If the test is negative there is still a 50% chance of

recurrence (NPV=42%)

Debiec et al, Am J Transplant 2011, 11:2144 ;

Debiec et al, JASN 2012, 23:1949 ; Larsen and Walker, Transplantation 2013 ;

Kattah A et al, Am J Transplant, 2015 15:1349

Can anti-PLA2R be useful for the diagnosis and

monitoring of patients with recurrent

and de novo MN?

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What should we do in 2016?

• Assess anti-PLA2R antibody in all adult patients with a suspected

diagnosis of MN, starting with the IF test (specificity, 100% ;

sensitivity, 70 to 80%), and anti-THSD7A antibody in PLA2R-

negative patients

• Search for PLA2R antigen in kidney biopsies from all patients with

MN, and for THSD7A in PLA2R-negative biopsies

• Determine Ig subclass in kidney biopsies from all patients with MN

• Monitor anti-PLA2R antibody titer during follow-up and in grafted

patients with MN




- diagnostic tests




• Perspectives

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Antibodies and their targets

Y

Y

PLA2R/THSD7A

Y

Y

NEP

Y Y

Placenta

Maternal alloantibodies

Autoantibodies

A Endogenous antigen

and allo- or autoantibodies

Debiec et al, Semin Immunopathol 2014, 36:381

Planted

antigen Pathogenic

antibodies

Immunization

Y

Y YY

Food Therapeutic proteins Viruses

cBSA Arylsulfatase,

α-glucosidase

Hep B

Exogenous antigen and allo- or

xenoantibodies

B

α-enolase

SOD2

Aldose reductase

• Understand the genetic bases of disease

triggering, spontaneous remission and progression

by next generation sequencing

• Identify additional antigens and T cell populations

involved in triggering and progression

• Design new therapeutic strategies

What’s next ?

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From the podocyte to new therapeutic

approaches of autoimmune diseases

33

C5b-9 complex

Ubiquitin

proteasome

system

ER

stressDepletion of B-cells

(non specific)

Inhibiting complement

activation

Protecting the podocyte

Eliminating environmental factors:

diet, toxin

Depletion of B-cells

producing pathogenic

antibodies

Development of

antibody traps or

decoys

Reducing

autoantibodies

Inhibitors of ER stress

IgG Debiec et al, Lancet, 2015, 385:1983

Drug designB. Iorga, CNRS Gif

Quantum Rattle

Humbury, PNAS 2015

D. Bazin & C. Sanchez,

Collège de France

The expanding spectrum of human

membranous nephropathies

• Neonatal, alloimmune : NEP

• Early childhood MN : cationic BSA

• Enzymotherapy-induced MN in patients treated with ERT

- a-glucosidase

- arylsulfatase

• « Idiopathic » MN

- 75-85%: PLA2R (+ other specificities : AR, SOD2, enolase…?)

- <10 %: THSD7A (10% of PLA2R negative MN), associated with cancer?

• Secondary MN : Hep B antigens, other antigens to be identified

• Graft MN :

- Recurrent : PLA2R (> 50%)

- De novo : allo-immune

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• Substitute molecular signatures for

uniform histological definition : Towards

new ontology…

• ….and personalized medicine, diagnostic

and therapy (specific immunoadsorption)

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Bergamo (I)

G. Remuzzi

P. Ruggenenti

Nijmegen (NL)

J. Wetzels

J. Hofstra

UK

R. Kleta (London)

P. Brenchley (Manchester)

CNG (Evry)

D. Bacq-Daian

V. Guigonis (Limoges, F)

A. Bensman (Paris, F)

G. Deschênes (Paris, F)

P. Niaudet (Paris, F)

T. Ulinski (Paris, F)

J. Nauta (Rotterdam, NL)

F. Janssen (Brussels, B)

J. Nortier (Brussels, B)

D. Bockenhauer (London, UK)

M. Kemper (Hamburg, D)

F. Emma, M. Vivarelli (Rome, I)

B. Stengel (Paris, F)

Acknowledgments

Paediatricians

pathophysiologie des glomérulonéphrites...

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