Systemic lupus erythematosus

서울의대 류마티스내과 이은영

Table of Contents

• Introduction• Clinical aspect of SLE• Basic science of SLE - overview - B cell biology - cytokine network - organ damage• Summary

Introduction

• Systemic lupus erythematosus (SLE)– Autoimmune disease

• Autoantibodies• Immune complex

– Multi-organ involvement– Heterogenous manifestations

– Unclear pathogenesis– Unpredictable acute flare

Epidemiology

• Epidemiology– ‘Disease of women of child-bearing age’

– Between late 10s and early 40s– M : F = 1 : 9 (1 : 2 in the child & aged)– Black > White

• Prevalence– 200/100,000 (Black)– 40/100,000 (Northern Europeans)

• Incidence– 1.8-7.6/100,000 (America)

– 3.3-4.8/100,000 (Europe)

pathogenesis

• Abnormal immune re-sponse

– Activation of innate immunity (dendritic cells)

– Activation of adaptive immu-nity (antigen-specific T & B cells)

– Inhibition of regulatory & in-hibitory T cells

– Reduced clearance of apop-totic cells & immune com-plexes

Im-mune Reac-tion

Genetic factor Environmental factor

Etiology

• Genetic factor– Concordancy in twins

• 50-60% in monozygotic twins• 5-10% in dizygotic twins

– Familial aggregation in 10%

– Association with gene polymorphisms• Increased frequency of HLA-B7, B8, DR2, DR3 &

DQw1• Complement; C4AQ0, C1q or C4 deficiency• Fc γ receptor IIA low-affinity phenotype

• Genetic factor– Chromosome Loci and Genes Associated with SLE

Dendritic cell function & IFN signalingIRF5, STAT4, SPP1, IRAK1, TREX1, TNFAIP3, TNIP1, PRDM1, PHRF1, TYK2, SLC15A4, and TLR8

Immune-complex processing and innate immunityITGAM, C1QA, C2, C4A, C4B, FCGR2A, FCGR3A, FCGR3B,KLK1/3, KLRG1, and KIR2DS4

Other genesPXK, ICA1, XKR6, and SCUBE1

T cell function and signalingPTPN22, TNFSF4, PDCD1, IL10, BCL6, IL16, TYK2, PRL, STAT4, and RASGRP3

Cell cycle, apoptosis, and cellular metabolismCASP10, NMNAT2, PTTG1, MSH5, PTPRT, UBE2L3, ATG5, and RASGRP3

B cell function and signalingBANK1, BLK, LYN, BCL6, and RASGRP3

Transcriptional regulationJAZF1, UHRF1BP1, BCL6, MECP2, ETS1, and IKZF1

SLE-associated locus

Tsokos GC. N Engl J Med. 2011;365(22):2110-21

• Hormonal factor– Androgen as a suppressor and estrogen as an accel-

erator• Environmental factor

– Infection (viral, bacterial)• EBV-homology between Sm Ag & EBNA (PPPGMRPP

vs PPPGRRP)• EBV viral load ↑, serologic response, impaired CD8

response– Drugs – UV light

• Abnormalities in the regulatory mechanism of the im-mune response – Abnormalities and dysregulation of cytokines or apop-

tosis

Clinical symptoms and signs

• skin

Discoid rash

Malar rash

SCLE

• Joint involvement– 95%– Hand, wrist, knee– Rare deformity

• Avascular necrosis of bone– 5-10% – Most common on femoral head– SLE 자체 혹은 Steroid 치료와

연관

• Renal involvement

• Pleuritis, pericarditis

• CNS involvement

Target sign

• Gastrointestinal involvement – lupus enteritis, lupus pancreatitis,

…

• Vascular occlusion - antiphospholipid syndrome: stroke,

coronary artery disease, …

Laboratory findings

• Antinuclear antibody - 핵 내에 있는 여러 항원을 targeting 하는 항체

– ANA-positive sera 는 여러가지 다른 핵내 항원들과 반응

– ds-DNA small nuclear ribonucleoproteins: Ro (SS-A), La (SS-B), nRNP,

& Sm enzymes: topoisomerase-1 (Scl-70) histone proteins

• 표준 검사 : indirect immunofluorescence– ANA by EIA

+

Hep-2 cell

Hep-2 cell nucleus Serum of patients

+

+FITC-tagging 2 Ab

• ANA 양성인 질환이나 condition 은 매우 다양 .

• Most useful in SLE; sensitive but not specific for SLE

• Tan EM et al. Range of antinuclear antibodies in "healthy" individuals. Arthritis Rheum. 1997;40(9):1601-11.

– 정상인에서 ANA 양성률• 31.7% at 1:40 dilution • 13.3% at 1:80 dilution• 5.0% at 1:160 dilution• 3.3% at 1:320 dilution

– Best discriminating dilution is 1:160 • Sensitivity 95% in SLE• Sensitivity 87% in systemic slcerosis

Titer of ANA positivity

Patterns of ANA

CREST SyndromeAnti-centromereCentromere(discrete speckled)

Systemic slcerosisInflammatory myopathy

Anti-Scl-70Anti-PM-Scl

Nucleolar

SLEAnti-dsDNAPeripheral (rim)

SLEMCTDSjgoren's syndromeSystemic slcerosis

Anti-SmAnti-RNPAnti-Ro/SSAAnti-La/SSB

Speckled

SLEAnti-dsDNAHomogeneous

Associated diseaseSpecific antibodyPattern

Anti-ENA

• ANA 의 subset, ENA(extractable nuclear antigens)에 대해 반응

• 질환과의 연관성– Anti-Ro: primary Sjogren’s syndrome, SLE– Anti-Scl 70: systemic sclerosis (diffuse scleroderma)– Anti-centromere: systemic sclerosis (limited

scleroderma)– Anti-Jo-1: Polymyositis and dermatomyositis– Anti-Smith: SLE– Anti-RNP: mixed connective tissue disease

• Sensitivity 가 낮기 때문에 , rheumatic disease 가 의심되면서 ANA 강양성일 때 검사를 내는 것이 바람직하다– Diagnostic information– Possibility of more severe disease manifestations

• 진단기준

Treatment

• Limitation– No cure– Rare complete sustained remissions

• Therapeutic goal– Control acute flares– Relieve symptoms– Prevent organ damages

Therapeutic algorithm

Life-threatening ?

Conservative

Hydroxychloroquine, ..

No

High dose corticosteroid

Yes

Improved QOL ?

Low dose corticosteroid

No

Cyclophos-phamide

Mycopheno-late mofetil

Mycophenolate mofetil/azathio-prine

Biologic agent

Stem cell transplantation

No response

Basic science of SLE

Disease course of systemic lupus erythematosus (SLE).

Bertsias G K et al. Ann Rheum Dis 2010;69:1603-1611

The Spiral of disease progress in SLE

Apoptosis and antigen• In SLE, apoptotic cells become secondarily necrotic because of

their impaired clearance.

Eggleton, P. 2006. Antigen–Antibody Complexes. eLS.Nature Genetics 2000;25:135

전신 홍반 루푸스 발생전 자가항체의 존재

• At least one SLE autoantibody was present before the diag-nosis in 88% of SLE patients . – ANA, anti-phospholipid, anti-Ro, and anti-La in a mean

3.4 years before the Dx.– Anti-ds DNA antibodies in a mean 2.2 years before the

Dx.– Anti-Sm and anti-nRNP in a mean 1.2 years before the

Dx.

Arbuckle MR, et al. N Engl J Med. 2003;349(16):1526-33.

전신 홍반 루푸스의 발병모델

Harrison’s Principles of Internal Medicine. 18th Eds.Robbins and Cotran Pathologic Basis of Disease.8th Eds.

Nature Rev Rheumatol 2010;6:339-47.

Cytokines involved in the pathogenesis of SLE

B cell biology

• Role of B cells in SLE - Loss of B cell tolerance - Abnormalities in the B cell compartment - Initiation and propagation of autoimmunity - Autoantibody-independent function

Loss of B cell tolerance

• Gene defects may affect

1) B-cell activation thresholds (eg, Fc receptor [FcR])

2) B-cell longevity (eg, B-cell activator of the tumor necrosis factor family [BAFF] transgenics)

3) apoptotic cell/autoantigen processing (eg, mer knockout)

Abnormalities in the B cell compartment in human SLE

• Healthy subject

- Important tolerance checkpoint operates to censor autoreactive B cells in the mature naive compartment

- 50% to 75% of newly produced human B cells are autoreactive and must be silenced by tolerance mechanisms

• Key checkpoints

- immature B-cell stage in the BM

- between new transitional emigrants and mature B cells in the pe-riphery

• SLE

- Defect in transitional B-cell checkpoint

B cell development, selection, and function

• increased calcium flux on signaling through the BCR

- high or aberrant expression of costimulatory molecules (CD80, CD86, and CD40 ligand)

• abnormalities in B-cell homeostasis - naive B-cell lymphopenia - expansion of peripheral blood plasma cells - increased transitional B cells - expansion of activated memory B-cell subsets

Abnormalities in the B cell compartment in human SLE

Initiation and propagation of autoimmunity

• Immune dysregulation by B cells in SLE - serving as the precursors of antibody-secreting

cells - taking up and presenting autoantigens to T cells - helping to regulate and organize inflammatory

responses through cytokine and chemokine se-cretion

- regulating other immune cells

Immune complex binding -> activation of plasmacytoid dendritic cells (DCs) by costimulation of TLRs (TLR-7, -8, or -9) and FcRs -> stimulating the secretion of large quantities of IFN-a -> activation and maturation of DCs and stimulation of T and B cells -> myeloid DCs produce BAFF, triggers more B-cell activation

Binding autoantibodies-> can directly trigger activation and proliferation of autoantibody-producing B cells

- Deficiency of TLR-7 or -9 - prevent autoAb production in mouse models- Mechanisms of action of antimalarials - inhibition of TLR signaling

Autoantibody-dependent and independent mechanisms

Recruit CXCR5+ follicular T helper (TFH) cells to GC -> influence of B cells on TFH cells via ICOSL and OX40L cos-timulation -> hyperactive GC, breakdown of B-cell tolerance, autoAb production, lupus-like phenoy-type

Cytokines involved in SLE

• Activation of antigen-specific CD4+ T cell Activation of B cells by cytokines

– TNF-α (Tumor necrosis factor-α)– IFN type 1, 2 (Interferon type 1, 2)– BLyS (B lymphocyte stimulator)– IL-6, IL-10 (Interleukin-6, 10)

– IL-2, TGF (Transforming growth factor) ↓• Decreased induction of regulatory & inhibitory T cells

Roles of pro- and anti-inflammatory cytokines in SLE

B-cell growth factors

Ligands

ReceptorsBAFF-R BCMA TACI

BLyS APRIL Heterotrimer

Proteoglycans

Increased B-cell survivalCostimulation of B-cell prolferation

Ig class switch recombination Enhanced APC function Germinal center formation Regulation of B-cell tolerance

Sequester APRIL at cell surface to improve TACI and/or BCMA sig-nalling?

Mediate plasma cell trafficking

Issacs JD, et al. EULAR 2007, Barcelona #SP0069

Interferon-alpha in SLE

• Family of type I IFNs: IFN-α, IFN-β

- induced by DNA and RNA virus infection (through intracellular nucleic

acid receptors or after engagement of TLR: TLR3 for double-stranded RNA, TLR7 or -8 for single-stranded RNA, or TLR9 for demethylated CpG-richDNA)

- mainly by plasmacytoid dendritic cells (pDCs)

• Function of IFN-α - differentiation of monocytes into dendritic-like cells

- induction of natural killer and natural killer T cells

- promotion of IFN-γ production

- support for B-cell differentiation into class-switched antibody produc-ing cells

- occasionally induce apoptosis -> produce self antigen

Insights from gene expression studies

• Microarray

- increased levels of type I IFN–induced genes in lupus PBMCs (MX1, the OAS family, and IFIT1)

- both type I IFNs and type II IFN (IFN-γ)

• fluctuation of IFN levels in individual patients

- ELISA platforms for measuring IFN-α have not been use-ful

- fluctuations in IFN-inducible gene expression in PBMC over time, in some cases, with close parallel to fluctua-tions in disease activity scores or response to therapy

Bertsias G K et al. Ann Rheum Dis 2010;69:1603-1611

In SLE, all pathways lead to endogenous nucleic acids-mediated production of interferon (IFNα).

• Advances in research into mechanisms of IFN pathway activation in SLE

- Genetic contributions to type I interferon production and response (IRF5, TRF7, TNFAIP3, STAT4, ..)

- Molecular pathways mediating production of IFN-α (Fc receptor, TLR7, TLR9, anti RBP, .. )

- IFN-α in murine lupus model (pristane administra-tion)

Mechanisms of organ damage in SLE

Animal model of SLE

• Spontaneous Lupus - NZB/W F1 - MRL/lpr - BXSB/Yaa• Induced Models - Pristane-Induced Lupus Model - Chronic Graft-versus-Host Disease

Biomarkers of SLE• Previous: ex) GFR, serum creatinine, ESR, CRP…

• defined as a genetic, biologic, biochemical, or event re-lated

• correlate with disease pathogenesis or manifestations

• can be evaluated qualitatively and/or quantitatively in laboratories

• should be

(1) biologically active and pathophysiologically relevant

(2) be simple to use in routine practice

(3) accurately and sensitively change with disease activ-ity

Biomarkers in SLE

Overall disease activ-ity

Genes PTPN22, IRF-5, STAT-4, type I interferon, IFIT1, OAS1, LY6E, ISG15, Mx1, FCγIIa polymorphysm

Interleukins IL-22, IL-6, IL-10, IL-12, IL-18, IL-2 receptor α

Chemokines RANTES, CXCL-11, CCL-19, MCP-1, CXCL-13, IP-10

Other molecules CD27, Reticulocyte-C4d, BLys

Lupus diagnosis E-C4d, anti-ds DNA, ANA, AntinucleosomeOrgan specific

Renal involvement -serum

Antinucleosome, Anti-C1q, α-actinin, anti-α-ac-tinin, Adrenomedulin

Urine Endothelial-1, Lipocalin-2, U-MCP-1, Migration inhibition factor, Adiponectin, VCAM-1, P-se-lectin, CXCL-16, FOXP3, TWEAK, Osteoprote-gerin

Neural Antihistone, Anti-N, AECA, MMP-9, Anti-NMDA, Anti-NR2, Anti-P ribosome

Skin Anticyclic citrullinated peptide

Summary

• B cell is a critical player in the pathogenesis of SLE. B cells contribute to SLE pathogenesis by antibody-depen-dent and –independent mechanisms.

• Although the primary triggers of SLE and the IFN path-way remain undefined, many studies showed crucial roles of IFN pathway in SLE pathogenesis.

• To understand these cytokine abnormalities may be ben-eficial in figuring out the pathogenesis of SLE and devel-oping effective targeting therapeutics.