Article

IL-6 Modulates CD5 Expression in B Cells from Patients with Lupus by Regulating DNA Methylation

Research Unit EA2216 Immunology and Pathology, IFR148 ScInBioS, Université de Brest, Brest, France.
The Journal of Immunology (Impact Factor: 4.92). 06/2009; 182(9):5623-32. DOI: 10.4049/jimmunol.0802412
Source: PubMed

ABSTRACT

B lymphocytes from patients with systemic lupus erythematosus (SLE) are characterized by reduced expression levels of membrane CD5. Recent studies from our laboratory have revealed that the level of membrane CD5 is determined by the relative level of two alternative CD5 isoforms; CD5-E1A, which is expressed on the membrane, and CD5-E1B, which is retained in the cytoplasm. Using bisulfite sequencing and methylation-sensitive endonuclease assays we show that the promoter for the alternative CD5-E1B isoform is demethylated in B cells from patients with SLE but not in healthy controls. We go on to show that differential methylation is more pronounced following BCR engagement. As a result of this demethylation, CD5-E1B mRNA is transcribed at the expense of CD5-E1A mRNA transcription. We provide further evidence that production of high IL-6 levels by SLE B cells abrogates the ability of SLE B cells to induce DNA methyl transferase (DNMT1) and then to methylate DNA, an effect that is reversed in the presence of a blocking Ab to the IL-6 receptor. The pattern of demethylation of CpG islands in the CD5-E1B promoter in SLE B cells is similar to those in B cells from healthy controls stimulated in the presence of IL-6, or treated with the methylation inhibitor PD98059. The study reveals that engagement of the BCR with constitutive IL-6 down-regulates the level of membrane CD5, which negatively regulates BCR signaling, in SLE B cells. This altered signaling could, in turn, promote the activation and expansion of autoreactive B cells in SLE patients.

Full-text

Available from: Yves Renaudineau
IL-6 Modulates CD5 Expression in B Cells from Patients with
Lupus by Regulating DNA Methylation
1
Soizic Garaud,
2
* Christelle Le Dantec,
2
* Sandrine Jousse-Joulin,
Catherine Hanrotel-Saliou,
Alain Saraux,*
Rizgar A. Mageed,
Pierre Youinou,
3
*
and Yves Renaudineau*
B lymphocytes from patients with systemic lupus erythematosus (SLE) are characterized by reduced expression levels of mem-
brane CD5. Recent studies from our laboratory have revealed that the level of membrane CD5 is determined by the relative level
of two alternative CD5 isoforms; CD5-E1A, which is expressed on the membrane, and CD5-E1B, which is retained in the cyto-
plasm. Using bisulfite sequencing and methylation-sensitive endonuclease assays we show that the promoter for the alternative
CD5-E1B isoform is demethylated in B cells from patients with SLE but not in healthy controls. We go on to show that differential
methylation is more pronounced following BCR engagement. As a result of this demethylation, CD5-E1B mRNA is transcribed
at the expense of CD5-E1A mRNA transcription. We provide further evidence that production of high IL-6 levels by SLE B cells
abrogates the ability of SLE B cells to induce DNA methyl transferase (DNMT1) and then to methylate DNA, an effect that is
reversed in the presence of a blocking Ab to the IL-6 receptor. The pattern of demethylation of CpG islands in the CD5-E1B
promoter in SLE B cells is similar to those in B cells from healthy controls stimulated in the presence of IL-6, or treated with
the methylation inhibitor PD98059. The study reveals that engagement of the BCR with constitutive IL-6 down-regulates the
level of membrane CD5, which negatively regulates BCR signaling, in SLE B cells. This altered signaling could, in turn,
promote the activation and expansion of autoreactive B cells in SLE patients. The Journal of Immunology, 2009, 182:
5623–5632.
S
ystemic lupus erythematosus (SLE)
4
is associated with di-
verse clinical manifestations (1). The main features of au-
toimmunity in SLE are B cell hyperactivity, spontaneous
lymphocyte proliferation, and the production of pathogenic Abs to
self-Ags. B cell abnormalities in SLE also include excess cytokine
production, autoantigen presentation to T cells and modulation of
the function of other immune cells (2). Thus, SLE is generally
considered a B cell disease, a theme strengthened by the efficacy of
therapies targeting B cells. For example, therapeutic approaches
using depleting anti-CD20 has proved to be highly beneficial in
treatment of SLE (3). Further, neutralization of cytokines that pro-
mote B cell responses such as IL-6, or interruption of cognate T
cell and B cell interactions has been successful in early clinical
trials (4, 5). All this provides the rationale for further investigation
of mechanisms of B cell involvement in driving autoimmunity and
to develop more selective therapeutic targets.
The central role played by B cells in immunity necessitates that
its responses are tightly regulated. B cell responses are initiated by
signaling through the BCR. Signaling initiated following BCR en-
gagement is regulated by coreceptors and by a network of protein
tyrosine kinases and phosphatases. Recent findings suggest that
defects in BCR-mediated signaling can result in lupus autoimmu-
nity. For example, there is an association between SLE autoim-
munity and mutations in a number of genes that encode B cell-
specific signaling molecules including protein tyrosine kinases,
non-receptor phosphatase type 22, B cell scaffold protein with
ankyrin repeats 1 and the inhibitory IgG Fc
RIIb (6). In addition
to direct evidence for the effect of mutations in signaling molecules
on BCR-mediated signaling, the contribution of epigenetic factors
has also been proposed (7). The most commonly observed epige-
netic abnormality implicated in SLE pathology is altered DNA
methylation at the 5-carbon position of cytosines of CpG dinucle-
otides. DNA methylation is regulated by three DNA methyl trans-
ferases (DNMTs), DNMT1, DNMT3a, and DNMT3b. DNMT1
preferentially targets hemi-methylated DNA over non-methylated
DNA. DNMT3a and DNMT3b, in contrast, exhibit de novo activ-
ities. The methyl-CpG-binding domain (MBD) protein-4 is a DNA
glycosylase that acts preferentially on hemi-methylated CpGs and
initiates demethylation by replacing a 5-methylcytosine with an
unmethylated cytosine (8). The action of MBD2 on DNA de-meth-
ylation has been suggested, but remains controversial (9). DNA
de-methylation activates the expression of many genes, such as
CD21 in B cells in patients with rheumatoid arthritis (10), CD40
ligand in T cells from patients with SLE (11), and the expression
of silenced retroviral genes (12). Increased expression of genes
resulting from de-methylation was confirmed using DNA methyl-
ation inhibitors in T cells from patients with SLE. Among those
inhibitors the ras signal blocker PD98059 appears to be the more
*Research Unit EA2216 Immunology and Pathology, IFR148 ScInBioS, Universite´
de Brest and Universite´ Europe´enne de Bretagne;
CHU Brest, Hoˆpital Morvan and
Hoˆpital de la Cavale Blanche, Brest, France;
William Harvey Research Institute,
Barts and the London School of Medicine and Dentistry, Queen Mary University of
London, London, United Kingdom
Received for publication July 30, 2008. Accepted for publication February 18, 2009.
The costs of publication of this article were defrayed in part by the payment of page
charges. This article must therefore be hereby marked advertisement in accordance
with 18 U.S.C. Section 1734 solely to indicate this fact.
1
This work was supported by grants from the Conseil Regional de Bretagne, the
Conseil Ge´ne´ral du Finiste`re, and the French Ministry for Education and Research.
2
S.G. and C.L.D. contributed equally to the work.
3
Address correspondence and reprint requests to Prof. Pierre Youinou, Laboratory of
Immunology, Brest University Medical School Hospital, BP824, F-29609, Brest,
France. E-mail address: youinou@univ-brest.fr
4
Abbreviations used in this paper: SLE, systemic lupus erythematosus; ChIP, chro-
matin immunoprecipitation; DNMT, DNA methyl transferase; HERV, human endog-
enous retrovirus; HC, healthy control; MBD, methyl-CpG-binding domain protein;
LTR, long terminal repeat; SLEDAI, SLE disease activity index.
Copyright © 2009 by The American Association of Immunologists, Inc. 0022-1767/09/$2.00
The Journal of Immunology
www.jimmunol.org/cgi/doi/10.4049/jimmunol.0802412
Page 1
relevant inhibitor because it induces cellular defects similar to
those observed in SLE (13).
B cells that express the CD5 protein, also known as B1 cells,
primarily express BCRs that are autoreactive, have a reduced ca-
pacity to enter the cell cycle, and have a longer lifespan. One
model for the role of CD5 in intracellular signaling suggests that
surface CD5 modulates signaling from the BCR and thereby con-
trols autoreactivity (14). According to this model, it is necessary
that the level of membrane CD5 is maintained to control the
threshold of BCR-mediated signaling. In humans, three mecha-
nisms have been shown to be involved in regulating the level of
membrane CD5. These are shedding (15), internalization of the
protein (16), and transcriptional regulation through altered level of
expression of two alternative CD5 isoforms (17). The first isoform,
designated CD5-E1A, corresponds to the full-length CD5 protein
which is synthesized and translocated to the cell membrane. The
second isoform derived from an alternative promoter, designated
CD5-E1B, encodes a truncated form of the protein that lacks a
leader peptide and is retained intracellularly. Indeed, CD5-E1B is
a fusion transcript from a new exon (4) that incorporates the 5
long terminal repeat (LTR) of a human endogenous retrovirus
(HERV) sequence integrated at the time of old and new world
monkeys divergence estimated at 25–30 million years ago (18).
We recently observed that transcription of mRNA for this isoform
inversely correlates with the level of DNMT1 mRNA (19).
Here, we provide evidence that relative to B cells from healthy
controls (HCs), the level of DNA methylation in BCR-mediated B
cell activation in patients with SLE is reduced. A consequence of
this hypomethylation is increased expression of CD5-E1B. Excess
production of IL-6 augments CD5-E1B transcription. Based on
this observation, we propose that modulation of B cell autoreac-
tivity in SLE could be achieved by targeting IL-6.
Materials and Methods
B lymphocyte isolation
PBMCs were isolated from the blood of 25 patients with SLE and 25 HCs
by centrifugation on Ficoll-Hypaque. All patients fulfilled the 1982 Amer-
ican College of Rheumatology criteria for SLE (20). SLE activity was
assessed by the SLE disease activity index (SLEDAI), and those with
SLEDAI of 5 were considered active. The characteristics of SLE patients
and HCs are shown in Table I. The cells were stained with FITC-anti-CD19
and PE-anti-CD5 Abs, and CD5
CD19
B cells sorted on an Epics Elite
FACS (Beckman-Coulter). All sorted cells were 98% CD19
. Informed
consent was obtained from the patients before taking blood, and the study
protocol approved by the Institutional Review Board at Brest University.
The Daudi human B cell line was purchased from American Type Culture
Collection.
FACS analysis
FITC-anti-CD19 (clone J4-119) and PE-anti-CD5 (clone BL1a) were ob-
tained from Beckman-Coulter, whereas anti-DNMT1 and anti-p27
kip1
were
obtained from Abcam. Intracellular staining was performed after perme-
abilization of the cells with 70% methanol. Binding of primary unconju-
gated Abs was revealed with FITC-conjugated anti-mouse Abs (Jackson
ImmunoResearch).
In pilot experiments, the number of CD5 molecules per cell was quan-
tified by determining the amount of Ab binding to the cells (ABC) at
saturating concentrations, using the Quantum Simply Cellular kit (Flow
Cytometry Standards). Arbitrary ABC value was then determined from a
standard ABC curve generated from the mean fluorescence intensity ob-
tained from the FACS analysis of 50
l calibrated microspheres stained
with 20
l of the same anti-CD5 Ab.
Cell culture
FACS-sorted B cells were suspended in RPMI 1640 supplemented with
10% heat-inactivated FCS, 2 mM L-glutamine, 200 U/ml penicillin and 100
g/ml streptomycin. B lymphocytes were seeded at 2 10
5
cells per well,
and incubated with 1
g/ml anti-IgM Ab-coated Sepharose beads (BioRad)
and 10 U/ml IL-2, in the presence or absence of 10 40 ng/ml anti-IL-
6RAb (R&D Systems), or 100 ng/ml rhIL-6 (Immuno Tools). Repression
of DNMTs was achieved by incubating the cells with 50
Moftheras
signal blocker PD98059. IL-6 and IFN-
were detected in sera and IL-6 in
the supernatant of cultured cells using ELISA kits according to the man-
ufacturer’s instructions (Beckman Coulter).
mRNA extraction and quantitative RT-PCR
Total mRNA was extracted using the RNAble method (Eurobio), and
cDNA synthesized by reverse transcription in 20
l volume with Super-
script II RNase H-RT (Invitrogen Corporation). Quantitative RT-PCR was
conducted in 20
l mixtures containing 50 ng template cDNA, 1X Sybr
Green PCR Master mix (Applied Biosystems), and 500 nM of each primer
(Table II). As described in detail elsewhere (17), CD5 promoter usage was
evaluated using two sets of primers. All assays included a negative control
which consisted of the reaction mixture with no template, and a positive
control which consisted of the mixture with 18S rRNA. Comparison of
cycle thresholds was completed with the 2
⫺⌬⌬ct
method using 18S as an
internal control.
RACE
The 5 transcript ends were amplified from mRNA using SMART-RACE
kit (Clontech). As described previously (17), the first strand of cDNA was
synthesized using the sense UPM primer and the gene-specific antisense
primer CD5 E5 (Table II). The PCR protocol included an initial denatur-
ation step at 94°C for 5 min, starting 5 touchdown-PCR cycles of dena-
turation at 94°C for 30 s and annealing at 72°C for 3 min. These cycles
were followed by another 5 cycles of 94°C for 30 s, 70°C for 30 s, and
72°C for 3 min, then with a decreasing temperature for 35 cycles of 94°C
for 30 s, 68°C for 30 s, and 72°C for 3 min. A nested PCR was performed
using the sense NUP primer and the gene-specific antisense primer CD5
E3. The second PCR round was for 40 cycles of 30 s at 94°C, 1 min at
56°C, and 1 min at 72°C with a final extension at 72°C for 10 min.
Methylation-specific PCR
This assay is based on the inability of some restriction enzymes to digest
a methylated 5-C
m
G-3 site. Genomic DNA was purified using QIAmp 96
DNA blood kit (Qiagen) and digested with 20 U of the methylation-sen-
sitive restriction enzymes HpaII, HaeII, FauI, HgaI, or the methylation-
insensitive restriction enzyme MspIfor3hat37°C. Undigested genomic
DNA was used as positive control. The PCR primers were positioned up-
stream and downstream of the recognition site in the promoters of E1A and
E1B of the cd5, cd19, cd70, Pax5, Syk, and HRES-1 genes (11, 19, 21, 22).
The PCR protocol included an initial denaturation at 94°C for 5 min, fol-
lowed by 35 cycles of denaturation at 94°C for 30 s, annealing at 56°C for
1 min, and primer extension at 72°C for 1 min; PCR cycles were followed
by final extension at 72°C for 10 min. The PCR products were separated on
agarose gel and visualized with 0.5
g/ml ethidium bromide.
Table I. Demographic and clinical characteristics of SLE patients and
HCs included in the study
Patients Controls
n 25 n 25
Age (years) 47.6 15.1 22–74
a
43.3 10.7 28–68
Female (%) 19 (76) 17 (68)
Ethnicity, Caucasian 25 25
SLEDAI score 3.7 5.3 0–19
SLE manifestations
Diseases duration 11.1 8.1 0–19
Skin disease 52%
Arthritis 72%
CNS disease 12%
Lupus nephritis 48%
Heart 32%
ANA 100%
Anti-dsDNA 64%
Medication usage (%)
Steroids 60%
Antimalarials 72%
Cytotoxic agents 20%
a
Mean SD min max.
5624 IL-6 CONTROLS DNA METHYLATION AND CD5 IN LUPUS B CELLS
Page 2
Bisulfite sequencing
To determine the methylation status of DNA, non-methylated cytosines
were converted to uridines by bisulfite treatment using the EZ-DNA meth-
ylation-Gold kit according to the manufacturer’s instructions (Zymo Re-
search). Unmodified DNA (100 ng) was amplified 40 times at 56°C using
specific primers. The bisulfite-converted DNA was amplified by nested
PCR using two rounds of 40 cycles each at 56°C with primers specific for
methylated cytosines (Table II). PCR products were purified using the high
pure PCR product purification kit (Roche), and directly sequenced with
internal primers by means of the BigDye Terminator Cycle Sequencing kit
using an automated ABI-310 genetic analyzer (Applied Biosystems). The
electrophoregram T and C peaks were quantified and methylation status
determined as [peak (C)/peak (T) peak (C)] 100. At the same time, the
unmodified DNA was amplified and sequenced using specific primers.
Chromatin immunoprecipitation
Chromatin immunoprecipitation (ChIP) was conducted using the EpiQuik
kit (Epigentek Group) according to the manufacturer’s instructions to eval-
uate activation of the CD5-E1B promoter. In brief, sonicated DNA (200
1000 bp) was transferred into strip wells precoated either with mouse anti-
RNA polymerase II, or with a nonspecific mouse IgG, used as a negative
control. After a 90-min incubation at room temperature and extensive
washes, precipitated DNA-protein complexes were treated with 250
g/ml
proteinase K in the DNA release buffer for 15 min, and left in the same
buffer for 90 min at 65°C. The DNA samples were collected by the P-spin
columns, washed with ethanol, and eluted. Using purified DNA as a tem-
plate, PCR was performed using GAPDH and CD5-E1B-specific primers
(Table II) and 40 cycles at 56°C. PCR products were separated on agarose
gel, and visualized with 0.5
g/ml ethidium bromide.
Computational promoter analysis
Putative transcription factor binding sites were identified by using Alibaba,
version 2.1, the transcription element search system (http://www.cbil.
open.edu/tess/index.html) and Genomatix (http://www.genomatix.de).
Statistics
The results were expressed as arithmetic means with SD. Comparisons
were made using the Mann-Whitney U test for unpaired data and the Wil-
coxon test for paired data. Correlations were established using Spearman’s
rank correlation.
Results
CD5 expression in B cells
The percentage of CD5-expressing B cells was similar in the 25
SLE patients and 25 HCs (Fig. 1A). However, membrane density
of CD5 on B1 cells was lower in the patients (Fig. 1B) compared
with the controls (49,971 15,124 vs 80,703 22,462; p
0.001). A representative example is depicted in Fig. 1C.
Table II. Oligonucleotide primers used in the study
a
Oligonucleotide Sequence Method
CD5-E1A sense 5-ATGCCCATGGGGTCTCTGCAAC-3 Quantitative PCR
CD5-E1B sense 5-GCTGAACACAGGGAAGGAAC-3 Quantitative PCR
CD5-E3 antisense 5-GCCTGGAAATCTGGGTCATA-3 Quantitative PCR
DNMT1 sense 5-CCTGTACCGAGTTGGTGATGGT-3 Quantitative PCR
DNMT1 antisense 5-CCTTCCGTGGGCGTTTC-3 Quantitative PCR
DNMT3a sense 5-CTCCTGTGGGAGCCTCAATGTTACC-3 Quantitative PCR
DNMT3a antisense 5-CAGTTCTTGCAGTTTTGGCACATTCC-3 Quantitative PCR
DNMT3b sense 5-CTCGAAGACGCACAGCTGACGAC-3 Quantitative PCR
DNMT3b antisense 5-CCTATAACAACGGCAAAGACCGAGC-3 Quantitative PCR
MBD2 sense 5-CCATGGAACTACCCAAAGGTCTT-3 Quantitative PCR
MBD2 antisense 5-CAGCAGATAAAAGGGTCTCATCATT-3 Quantitative PCR
MBD4 sense 5-TCTAGTGAGCGCCTAGTCCCAG-3 Quantitative PCR
MBD4 antisense 5-TTCCAATTCCATAGCAACATCTTCT-3 Quantitative PCR
18S sense 5-GGCTACCACATCCAAGGAAGGCAG-3 Quantitative PCR
18S antisense 5-CCAATTACAGGGCCTCGAAAGAGTC-3 Quantitative PCR
CD5-E5 antisense 5-AGTCTCTGGCAGCTGCTTCAAGAA-3 5RACE
CD5-E3 antisense 5-TGCCATCCGTCCTTGAGGTAGAC-3 5RACE
CD5 promoter-1B sense 5-GTGAAGGGCTGCTTACTGCACACAGC-3 Methylation-PCR
CD5-E1B antisense 5-CAGCCACTGCGTTGATCCTCCACAG-3 Methylation-PCR
CD5 promoter-1A sense 5-CTGGAAGGGTAAAGCAGGGTTCTC-3 Methylation-PCR
CD5-E1A antisense 5-GGAGTCTGCAACAAGAACTGGCATC-3 Methylation-PCR
CD5 promoter-1B sense 5-TTTTATTTGTGAAATGGAAAGTTGT-3 Methylation-PCR
CD5-E1B antisense 5-AAATTCCCAAAACCAATCCTATC-3 Bisulfite sequencing
CD5 promoter-1B sense 5-TGTGAAATGGAAAGTTGTGTTTATT-3 Bisulfite sequencing
CD5-E1B antisense 5-AACATACCATAAATAATTAAACCAC-3 Bisulfite sequencing
CD5 promoter-1A sense 5-GAATTGGTATTATGTTGTTTATTTTT-3 Bisulfite sequencing
CD5-E1A antisense 5-CTCCCTACCAACCTAAAAACTACTC-3 Bisulfite sequencing
CD5 promoter-1A sense 5-ATTGTTTTAGTTTTGGGTATTTTGG-3 Bisulfite sequencing
CD5-E1A antisense 5-CCCCCTACAATCTCTCTTACACTAA-3 Bisulfite sequencing
CD5-E1B sense 5-TCTGCCAAAGAGGTTCAAGC-3 ChIP
CD5-E1B antisense 5-TGCATGCACCGGTAATTAGA-3 ChIP
GAPDH sense 5-TACTAGCGGTTTTACGGGCG-3 ChIP
GAPDH antisense 5-TCGAACAGGAGGAGCAGAGAGCGA-3 ChIP
CD19 promoter sense 5-AGCGTGGCAGGGAGGAGGCAAGTGTT-3 Methylation PCR
CD19 promoter antisense 5-GCGAGGAGGTGGCATGGTGGTCAGA-3 Methylation PCR
CD70 promoter sense 5-TCACCCAAGGTCAGGAGTTC-3 Methylation PCR
CD70 promoter antisense 5-CCATCTCAACTCACCCCAAG-3 Methylation PCR
Pax5 promoter sense 5-GCAATAGTCAGGACCCCAAC-3 Methylation PCR
Pax5 promoter antisense 5-TTCTCGCCAACATCACAAGA-3 Methylation PCR
Syk promoter sense 5-GGCAGCCCCACCTTCTCT-3 Methylation PCR
Syk promoter antisense 5-CGCGGCTCTTCCTCATTT-3 Methylation PCR
HRES-1 promoter sense 5-GCATATGCACTGGGAAAGGT-3 Methylation PCR
HRES-1 promoter antisense 5-CCGCCTTTTCAAGTTTCCTC-3 Methylation PCR
a
E1A, exon 1A; E1B, exon 1B; DNMT, DNA methyltransferase; MBD, methyl-CpG binding domain protein.
5625The Journal of Immunology
Page 3
Expression of CD5-E1B, which is retained in the cytoplasm,
reduces membrane expression of CD5-E1A (17, 19). This suggests
that CD5-expressing B cells may, under certain physiological con-
ditions (such as activation), preferentially up-regulate CD5-E1B
relative to CD5-E1A. To test this proposition, levels of CD5-E1A
and CD5-E1B mRNA were determined using a 5 specific real
time PCR following 24h anti-IgM stimulation of FACS-sorted
CD5-negative B cells from the blood of 10 SLE patients and 15
HCs (Fig. 1D). BCR engagement of the cells raised the level of
CD5-E1B mRNA in B cells from the patients (54.4 68.1-fold)
but not in those from the controls (0.5 0.2-fold). In contrast,
after BCR engagement expression of CD5-E1A is increased both
in SLE patients and in HCs (7.7 4.9-fold and 5.5 5.6-fold,
NS). The 5-RACE analysis of CD5 cDNA using B cells from HCs
FIGURE 2. Amplification of methylation-sensitive, endonuclease-digested genomic DNA reveals methylation status of the alternative promoters of CD5
in resting B cells. A, Schematic representation of the affected promoters. The CD5-E1B promoter arises from a LTR element subdivided into U3, R, and
U5 regions. The two splice donors (SD) are indicated, and positions of DNA-specific primers shown. The 1177-bp CD5-E1B amplicon contains six
HpaII/MspI motifs (5-CCGG-3) at positions 8736, 8726, 8522, 8268, 8114, and 7795 bp, and one HaeII motif (5(A/G)GCGC(T/C)3)at
position 8393bp according to numbering from the established ATG initiation site in exon 1A (22). The 783-bp CD5-E1A amplicon contains one HgaI
motif (5-GACGC(N)
5
-3) at position 151, one FauI motif (5-CCCGC(N)
4
-3) at position 96, and two HpaII/MspI motifs at positions 65 and 87.
B, Analysis of CD5-E1B promoter methylation by amplification of genomic DNA digested with methylation-sensitive HaeII, HpaII, or methylation-
insensitive MspI enzymes. C, Analysis of the CD5-E1A promoter region using HgaI, FauI, HpaII, and MspI enzymes. Undigested genomic DNA is
amplified by PCR, separated on agarose gel, and visualized with ethidium bromide.
FIGURE 1. CD5 expression in B cells. A, A scatter-
gram depicting percentage of CD5-expressing B cells in
25 SLE patients and 25 HCs. B, The number of CD5
molecules per cell is given in the scattergram. The num-
bers are expressed as the amount of anti-CD5 Ab bound
to the cell membrane. C, Representative FACS profile
for cell surface expression of CD5 in blood B cells from
one SLE patient (bold line) and one HC (thin line). D,
Quantitative RT-PCR results presenting as histograms
revealing that a 24-h stimulation of B cells with anti-
IgM increased CD5-E1B transcription in B cells from
SLE patients but not HCs. Incubation of anti-
IgM-activated B cells from HCs with PD98059 resulted
in up-regulation of CD5-E1B. Mean and SD of data
from 10 SLE patients and 15 HCs are shown. E, CD5
5-RACE analysis of cDNA revealing that CD5-E1B
(639 bp) and CD5-E1A (259 bp) are induced when B
cells from the HCs were stimulated with anti-IgM in the
presence of PD98059, whereas only CD5-E1A (259 bp)
is induced in the presence of anti-IgM. These data in-
dicate that MAPK/Erk has a role in regulating CD5-
E1B up-regulation.
5626 IL-6 CONTROLS DNA METHYLATION AND CD5 IN LUPUS B CELLS
Page 4
confirmed that BCR engagement induce CD5-E1A but did not in-
duce CD5-E1B transcripts (Fig. 1E).
To test the hypothesis that epigenetic changes in the cd5 gene
contribute to the generation of alternative transcripts in activated B
cells from patients with SLE, BCR engagement was re-evaluated
in the presence of PD98059 which decreases DNA methylation. In
these conditions, an up-regulation of CD5-E1B upon anti-IgM/
PD98059 stimulation was observed in B cells from HCs using
real-time PCR (61.5 11.9-fold) and 5-RACE analysis (Fig. 1, D
and E).
The CD5-E1B promoter is hypomethylated in resting SLE
B cells
To determine whether epigenetic changes result in increased CD5-
E1B in SLE B cells, genomic DNA from six randomly selected
patients and seven HCs were analyzed for the level of DNA meth-
ylation restriction enzyme treatment of the DNA followed by PCR
(Fig. 2A). The protocol is based on the inability of methylation-
sensitive restriction enzymes to cut methylated DNA. The results
of treatment with HaeII enzyme revealed that the CD5-E1B pro-
moter was de-methylated in B cells from all 6 SLE patients but in
none of the 7 HCs (Fig. 2B). Treatment with HpaII confirmed
demethylation in two of six SLE patients but in none of the HCs.
The positive control was the DNA methylation of Daudi cell line
cells (23). The negative control was the HpaII isoschizomer, MpsI,
that cut the CpG sequences so that there were no PCR products.
In addition to this data, the methylation status of the CD5-E1A
promoter was sought using HgaII, FauI and HpaII (Fig. 2C). The
results showed that the CpG motifs were de-methylated, or hemi-
methylated in B cells from both the SLE patients and HCs.
The U3 region in CD5-E1B is hypomethylated in B cells from
SLE patients
The presence of HaeII site (site 4) in the U3 region of the 5-LTR
element of HERV-CD5, and three HpaII sites upstream U3-LTR
(site 1) or in the R region of the 5-LTR (sites 7 and 13) raises the
possibility that the HERV U3-R-U5 regulatory elements may be
de-methylated in B cells from patients with SLE (Fig. 3A). To
address this issue, bisulfite-treated genomic DNA were amplified
and sequenced.
Bisulfite C3 T transition in SLE CD5-E1B amplicons were an-
alyzed and quantified as shown in Fig. 3B and supplemental Fig.
1.
5
Among 26 CpG sites studied in the 1439-bp amplicon of CD5-
EIB, five CpG sites are hemi- or de-methylated. These CpGs (sites
2 to 6) are located in the U3-LTR at positions 8466 from the
5
The online version of this article contains supplemental material.
FIGURE 3. The U3-LTR HERV-CD5 region is de-methylated in B cells from SLE patients. A, Regulatory motifs for transcription factor binding and
TATA box location within the U3 region. Circles and boxes identify the CpG and U3-R-U5 regions. The HpaII and HaeII sites are also indicated. B, The
level of CpG methylation was determined by bisulfite sequencing using genomic DNA obtained from six SLE patients (white) and seven HCs (black). CpG
sites are numbered as in A. C, Correlation between CD5 cell surface expression and methylation status for CpG sites 3 to 6. White circle, SLE patients;
black circle, HC subjects. , p 0.05; p 0.001.
5627The Journal of Immunology
Page 5
known ATG1 initiation site (24), 8396, 8393 (HaeII), 8347,
and 8363, respectively. De-methylated CpG motifs contain, or
are located near, the binding sites of E2/Rb family proteins (con-
sensus TTT(C/G)(C/G)CGC, position 8394 to 8391), E-box
family proteins (CA(N)
3
TG, 8391 to 8388), and STAT family
proteins (inverted consensus TT(N)
4
AA, 8353 to 8344).
When comparing SLE patients to HCs, the cytosine residues
near the E2/Rb binding sites 3 and 4, plus the CpG at site 5, were
significantly less affected by the bisulfite treatment in the SLE
patients (Fig. 3B, p 0.05). Furthermore, the level of methylation
of CpG sites 3 to 5, are inversely correlated with CD5 cell surface
expression in CD5
B cells (Fig. 3C, p 0.01). However, de
-
methylation of the CD5-E1B promoter identified in B cells from
the SLE patients could be due to gene polymorphisms. Such a
proposition was discounted because only one association between
a methylated CpG motif at position 8001 and a SNP site was
observed (supplemental Fig. 2).
In contrast to CD5-E1B promoter, the 791bp amplicon for CD5-
E1A which contains 12 CpG was equally de-methylated in B cells
from the SLE patients and HCs (Fig. 2C and supplemental Fig. 1).
De-methylated CpGs were located at positions: 148, 123, 102,
73 and 64. These regions contain, or are located nearby to con-
sensus binding sites for AP-1 (151), Sp-1 (120, 96), E-box fam-
ily proteins (50) and the INR transcriptional start site (61).
Activation modifies methylation of the CD5-E1B promoter
To assess the influence of BCR engagement on methylation of the
CD5 locus, FACS-sorted CD5-negative B cells from six SLE pa-
tients and six HCs were stimulated with anti-IgM for 24 h. Meth-
ylation patterns were then compared in these activated cells with
the pattern of methylation in the cells before activation (Fig. 4). In
the SLE patients, engagement of the BCR did not modify CD5
promoter methylation status, whereas in the HCs, it resulted in
methylation of the CD5-E1B promoter at positions 3 and 4 (Fig.
4D), but not that of CD5-E1A (not shown). Interestingly, when B
cells from the HCs were stimulated with anti-IgM in the presence
of PD98059, CpG sites 3, 4, and 5 were prone to demethylation
similar to what was seen in the SLE B cells. All these results are
consistent with previous findings that the U3-LTR regions in
HERV elements are prone to demethylation (25).
Analysis of DNA methylation enzymes
To gain insights into the cause(s) of de-methylation of the CD5-
E1B promoter in B cells from SLE patients, levels of mRNA for
DNMTs and MBDs were determined in B cells from ten SLE
patients and 15 HCs. Levels of DNMT1, DNMT3a, DNMT3b,
MBD2, and MBD4 were not different in B cells from the patients
and the controls (Table III). With regard to SLE activity, we failed
to find correlations between patients with SLEDAI 5(n 3)
and changes in DNMTs or MBDs activity. On the basis of our
observation that B cell activation through the BCR influences U3-
LTR methylation, we measured the level of mRNA for DNMT1
and MBDs by real-time PCR in B cells stimulated for 24 h with
anti-IgM from ten SLE patients and 15 HCs (Fig. 5A). The ex-
pression of DNMT1 was increased by 2.3 0.2-fold in B cells
from the patients and by 16.6 13.4-fold in the controls ( p
0.005). Importantly, the expression of MBDs was not affected by
FIGURE 4. Effect of BCR engagement on cd5 gene
methylation. A, Methylation of CD5-E1B promoter an-
alyzed by restriction enzymes and bisulfite sequencing.
Enzymes and symbols used are the same as in the leg-
end to Fig. 3. B, Effect of restriction enzymes on CD5-
E1A. C, The level of CpG methylation measured by
bisulfite sequencing with (white) or without (black)
BCR engagement in six SLE patients. D, CpG methyl-
ation in B cells from six HCs stimulated with anti-IgM
in the presence (gray) or absence (white) of PD98059.
, p 0.05.
Table III. Level of DNMTs and MBDs mRNA in resting B cells from
10 SLE patients and 15 HCs
a
Patients Controls
DNMT1 14.8 8.4 15.4 10.4
DNMT3a 1.03 0.52 0.61 0.76
DNMT3b undetectable undetectable
MBD2 44.2 22.9 37.1 19.4
MBD4 34.2 21.5 23.5 12.5
a
cDNA were subjected to quantitative RT-PCR (primers indicated in Table I).
Their relative expression was adjusted to 18S levels (10
6
).
5628 IL-6 CONTROLS DNA METHYLATION AND CD5 IN LUPUS B CELLS
Page 6
stimulation of the BCR or by the addition of the DNMTs inhibitor
PD98059.
FACS analyses verified that BCR engagement modulated DNMT1
expression. Results from four of ten independent experiments are de-
picted in Fig. 5B. Interestingly, DNMT1 staining showed two peaks,
DNMT1
dim
and DNMT1
bright
. According to this dichotomy, resting B
cells could be divided into 76.1 7.9% DNMT1
dim
and 23.8 7.9%
DNMT1
bright
cells in the patients and into 74.7 12.3% DNMT1
dim
and 25.3 12.3% DNMT1
bright
cells in the controls ( p NS). A
24-h culture of B cells with anti-IgM increased the proportion of the
DNMT1
bright
population to 86.1 12.2% in the HCs compared with
46.1 7.8% in the SLE patients ( p 0.05). Thus, these results
indicate that induction of DNMT1 following BCR engagement is re-
duced in patients with SLE.
The role of IL-6 in de-methylation and CD5-E1B expression
Based on our previous observations that IL-6 over-expression con-
trols the cell cycle in BCR-activated in B cells from SLE patients,
we predicted that IL-6 by arresting the cell cycle at late G
1
phase
may control the expression of DNMT1 and its capacity to meth-
ylate DNA and subsequently CD5 cell surface expression (26 –28).
To test whether IL-6 acts on its own, or requires engagement of
the BCR, FACS-sorted B cells from six HCs were stimulated for
48 h with rhIL-6 in the presence or absence of anti-IgM. Expres-
sion of CD5-E1B increased by 4.1 3.13-fold in B cells cultured
with rhIL-6, and by 54.8 11.3-fold in B cells cultured with
rhIL-6 and anti-IgM (Fig. 6A, p 0.05). The induction of CD5-
E1B upon IgM/rhIL-6 stimulation was also demonstrated by ChIP
FIGURE 5. Involvement of DNMTs on CD5-E1B
expression. A, Quantitative PCR measurement of
DNMT1, MBD2, and MBD4 mRNA levels in ten SLE
patients and 15 HCs following BCR engagement. Role
of activation of MAPK/Erk pathway in DNMT1 induc-
tion was examined in HCs using the PD98059 inhibitor.
B, Cytoplasmic staining of DNMT1 in methanol-per-
meabilized non-activated, or B cells activated with
anti-IgM.
FIGURE 6. The effect of IL-6 on CD5-E1B expres-
sion and promoter methylation. A, FACS-sorted B cells
from HCs were incubated with IL-6 in the presence, or
absence of anti-IgM, or anti-IL-6R Abs. Quantitative
PCR measurement of CD5-E1B (white boxes) and
DNMT1 (black boxes) in six HCs. B, CD5-E1B pro-
moter ChIP analysis using a nonspecific mouse IgG as
negative control (C), or a mouse anti-RNA polymer-
ase as positive control (C). C, Cytoplasmic staining of
DNMT1 and p27
kip1
as a marker of cell cycle arrest in
the G
1
phase in methanol-permeabilized B cells from
the HCs incubated with IL-6 in the presence or absence
of anti-IgM.
5629The Journal of Immunology
Page 7
analysis. This experiment showed that RNA polymerase II was
recruited to the CD5-E1B promoter upon anti-IgM/rhIL-6 stimu-
lation (Fig. 6B). Thus, rhIL-6 induces CD5-E1B expression and
this effect is more pronounced when B cells are activated through
the BCR.
The induction of DNMT1 mRNA by anti-IgM was negated in
the presence of rhIL-6 (Fig. 6A). The experiments were re-
peated in the presence of anti-IL-6R Ab to inhibit the activity of
IL-6. DNMT1 induction was restored (10.0 3.6 vs 0.63
0.25-fold without anti-IL-6R Ab, p 0.05) and CD5-E1B was
reduced (54.8 11.3 vs 35.6 5.2-fold without anti-IL-6R Ab,
p 0.05). Moreover, FACS analyses showed that the number
of DNMT1
bright
cells was reduced after anti-IgM stimulation in
the presence of rhIL-6 (86.1 12.2% vs 33.5 3.7%, p
0.05). A representative example of two experiments is shown in
Fig. 6C. We also studied whether these differences could be
attributed to a cell cycle blockade. As suspected, the cyclin-
dependent kinases inhibitor p27
kip1
was over-expressed in anti-
IgM/rhIL-6-stimulated B cells compared with rhIL-6 or anti-
IgM stimulation alone (Fig. 6C). Overall, IL-6 appears to
control CpG methylation in SLE B cells resulting, probably,
from its effect on arresting cells at the late G
1
phase of the cell
cycle.
Effects of IgM/IL-6 stimulation on promoters of other genes
To determine the extent of IL-6 effect on methylation, we deter-
mined the methylation status of other promoters (CD19, CD70,
Pax 5, Syk, and HRES-1) that are known to be regulated by meth-
ylation (11, 21, 22). In the six HCs studied (Fig. 7), the promoters
were hypomethylated in resting cells. Stimulation of B cells with
anti-IgM only increased the methylation of the HRES-1. This ef-
fect by anti-IgM was reversed in the presence of IL-6.
Effect of IL-6 on SLE B cells
To validate the role of IL-6 in the altered methylation status of
CD5-E1B in B cells in SLE patients, membrane CD5 expression
levels were compared between patients whose sera were IL-6 pos-
itive and negative. The presence of IL-6 in serum was associated
with decreased membrane CD5 expression (Fig. 8A, p 0.01). In
FIGURE 7. Anti-IgM-induced methylation of promoters for CD19,
CD70, Pax5, Syk, and HRES-1. A, B cells from HCs were incubated with
anti-IgM in the presence or absence of anti-IL-6R Ab. The methylation
status of all five promoters was determined by PCR using predigested
genomic DNA with methylation-sensitive HpaII, or methylation-insensi-
tive MspI. B, The methylation of the HRES-1 promoter was quantified by
calculating the ratio of HpaII-digested to undigested bands in six HCs.
, p 0.05.
FIGURE 8. IL-6-dependent modulation of methyl-
ation in SLE B cells. CD5 cell surface expression in
relation to the detection level of IL-6 (A) or IFN-
(B)
in the serum of 18 SLE patients. The detection limit
used corresponds to the sensitivity limit of the ELISA.
C, FACS-sorted B cells from six SLE patients were cul-
tured with anti-IgM in the presence or absence of 40
ng/ml anti-IL-6R Ab. All SLE patients, except one,
were inactive (SLEDAI 5). Dose effect response at 10
and 20 ng/ml anti-IL-6R were performed on three SLE
patients. Quantitative PCR measurement of CD5-E1B
(white boxes) and DNMT1 (black boxes). D, Effect of
anti-IgM/anti-IL-6R (gray) on CD5-E1B promoter
methylation status.
5630 IL-6 CONTROLS DNA METHYLATION AND CD5 IN LUPUS B CELLS
Page 8
contrast, changes in membrane CD5 expression were not associ-
ated with serum IFN-
(Fig. 8B). CD5 cell surface expression was
reduced in patients who had SLEDAI 5 (39,789 11,450 vs
51,294 15,215), but this was not significant (data not shown).
Finally, the effect of a blocking anti-IL-6R Ab was studied be-
cause we previously observed that anti-IgM stimulation of B cells
from SLE patients produced higher levels of IL-6 than matched
HCs (514.1 159.7 pg/ml vs 99.0 116.0 pg/ml, data not shown)
(26). Blocking the autocrine loop of IL-6 increased DNMT1 ex-
pression (58.9 13.5-fold with 40 ng/ml anti-IL-6R) and contrib-
uted to the methylation of the U3-LTR sites 3 to 5 (Fig. 8, C and
D). In addition, expression of CD5-E1B was reduced (17.2 3.5-
fold with 40 ng/ml anti-IL-6R vs 54.4 68.1-fold without, p
0.05). Further, this effect was dose-dependent.
Discussion
This study provides evidence for the notion that reduction in the
level of membrane CD5 on circulating CD5
B cells SLE is due
to increased expression of the cytoplasmic isoform of CD5, CD5-
E1B. As a consequence of reduced membrane CD5, increased
CD5-E1B limits the negative regulatory effects of CD5 on BCR-
mediated signaling. The available evidence indicates that mem-
brane CD5 increases the threshold of BCR-mediated responses
(14). The implication of such data is that regulation of CD5-E1B,
which in turn regulates expression of CD5, is involved in main-
taining the anergy status of autoreactive B cells. Results generated
from our previous studies indicated that the modulatory effects of
CD5 protein on BCR signaling are attributed to the CD5 isoform
which contains E1A, the previously documented exon 1. Introduc-
tion of cDNA for the recently identified CD5-E1B isoform into
CD5
T and B cells reduced membrane expression of CD5 protein
(17, 19). Coexpression experiments have also shown that in the
presence of CD5-E1B, CD5-E1A was not translocated to the mem-
brane but associated with CD5-E1B in cytoplasmic aggregates
(19). The exact dynamics of the interaction between CD5-E1B and
CD5-E1A remain unknown. However, we have established that
the stretch of amino acids from positions 286 400 in CD5-E1B is
crucial for reducing membrane CD5-E1A translocation (19). Func-
tionally, these data suggest that up-regulated CD5-E1B expression
in B cells could reduce the BCR activation threshold by Ags and
thus, promote autoimmunity.
Because CD5-E1B arises from the integration of an HERV el-
ement known to be silenced by DNA methylation (19), we pre-
dicted that epigenetic modifications could be involved in regulat-
ing CD5 isoform expression in B cells. Normally, methylation of
DNA is evident in CpG-poor regions and in regions of repetitive
sequences including LTR in HERV sequences. In contrast, CpG
islands present within gene promoters resist to methylation. In nor-
mal B cells, this paradigm holds true for the cd5 locus, where the
U3-LTR element is methylated while the CD5-E1A promoter is
not. However, in SLE B cells, the rate of de-methylation is higher
in the U3 region of the HERV-CD5 element. Consistent with this
observation is the finding that another HERV element, HRES-1,
was also integrated at the stage of old world primate divergence
(22). Indeed, expression of HRES-1 retroviral proteins, HRES-1/
p28 and HRES-1/Rab4 (29), and our observations on HRES-1 pro-
moter methylation status (Fig. 7) may hint to a global defect in
controlling repetitive elements in SLE. Our preliminary results are
indeed indicative that HRES-1 methylation pattern was not in-
creased in SLE patients upon BCR engagement. In this respect,
global DNA methylation has been reported to be altered in almost
all forms of SLE including drug-induced lupus (30). As a conse-
quence, it was postulated that epigenetic transformation modifies B
cell physiology resulting in polyclonal activation, IgG1 class-
switching (31), V(D)J rearrangement by RAG1/RAG2 enzymes
(32) and a shift in cytokine profiles (33). Altered methylation also
influences T cells in SLE causing up-regulation of T cell costimu-
lating molecules (CD70, CD40 ligand), and a shift in cytokine
profile from Th1 to Th2 (for review, see Ref. 34). We propose that
these alterations, together with our findings on CD5 down-regula-
tion, contribute to promoting autoreactivity.
De-methylation of DNA can be result from the inhibition or lack
of DNMTs or be due to specific enzymatic reactions including
MBDs or a combination of both. Thus, DNA methylation patterns
can be altered owing to a shift in the balance between MBD de-
methylation and DNMT methylation enzymes. Quantitative PCR
assays were performed to evaluate the relative levels of MBD and
DNMT transcripts in resting and in anti-IgM stimulated B cells. At
basal level, B cells from SLE patients and HCs had similar levels
of DNMT1, DNMT3a, MBD2, and MBD4. The amount of
DNMT3b was very low or undetectable in both SLE patients and
HCs as previously described for T cells (35). A recent study re-
ported reductions in DNMT1 in a subgroup of SLE patients (36).
However, this study was conducted using a relatively small cohort
and was not confirmed either in CD4
T cells (35) or in B cells by
the present study. In addition, the recently reported increase in
MBD2 and MBD4 in patients with SLE (37) was also not con-
firmed in our study. These differences may be because we have
examined B cells instead of CD4
T cells, or that the patient
population included in the other study was different. Interestingly,
analysis of stimulated B cells revealed that expression of DNMT1
was reduced following engagement of the BCR in SLE in agree-
ment with findings in stimulated CD4
T cells (13).
Our results, suggesting that DNA hypomethylation in activated
SLE B cells, could be attributed to cell cycle arrest in G
1
is sur
-
prising. The surprising aspect of the observation is based on the
fact that proliferation of lymphocytes did not differ between the
patients and HCs implying that decreased DNMT1 activity in SLE
was not due to a cell cycle arrest (13). However, inhibition of the
MAPK/Erk2 pathway was clearly associated with DNMT1 reduc-
tion in those patients (13, 38). Further, inhibition of this pathway
is likely to elicit cell cycle arrest through p27
kip1
induction (39,
40). However, inhibition of MEK/Erk2 pathway using PD98059 in
pro-B induces cell growth arrest with p27
kip1
accumulation (39).
Therefore, in such a setting, it was not surprising that PD98059
decreased methylation in HCs as in stimulated SLE B cells. Hence,
these data indicate that decreased activation of the Erk pathway
could be important for the development of autoimmunity (7). This
was previously confirmed in animal models showing that treating
normal mice with inhibitors of DNA methylation, or with Erk in-
hibitors causes a lupus-like disease (41). Further, Tg mice express-
ing dominant-negative MEK leads to overexpression of methyla-
tion-sensitive genes and the production of anti-dsDNA
autoantibodies by B cells (38).
The proposed involvement of IL-6 in promoting autoreactivity
is supported by in vitro and in vivo studies. For example, high
levels of serum IL-6 is correlated with lupus disease activity and
targeting IL-6 with blocking Abs is an effective treatment for SLE
(4). However, the precise mechanism by which IL-6-mediated B
cell proliferation, differentiation, and autoantibody production in
SLE remains to be elucidated. Repression of IL-6 is associated
with hypermethylation of its promoter in HCs whereas its overex-
pression in SLE is associated with promoter hypomethylation (42).
Interestingly, by treating B cells from HCs with IL-6 in the pres-
ence of anti-IgM, we have shown that CD5-E1B expression can be
significantly increased and that this correlates with a cell cycle
arrest in late G
1
phase. In addition, this effect is associated with an
Ig gene rearrangement following RAG re-expression (26). The loss
5631The Journal of Immunology
Page 9
of, or reduction in, the inhibitory effects of CD5 is associated with
RAG re-expression in B cells in patients with SLE and these may
synergize to induce autoantibody production.
In conclusion, the finding that IL-6 activates CD5-E1B tran-
scription is relevant for understanding mechanism of action and
therapeutic benefits of anti-IL-6. Thus, treatment of patients with
SLE with anti-IL-6R mAb could inhibit autoreactive B cell expan-
sion by restoring DNA methylation and cell cycle progression. In
addition, the data provide further evidence for the pivotal role of
CD5 in maintaining anergy in autoreactive B cells.
Acknowledgments
We are grateful to the Conseil Re´gional de Bretagne, the Conseil Ge´ne´ral
du Finiste`re, the College Doctoral International, and the Universite´ Europ-
e´enne de Bretagne for support. Thanks are also due to Cindy Se´ne´ and
Simone Forest for excellent secretarial assistance.
Disclosures
The authors have no financial conflict of interest.
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5632 IL-6 CONTROLS DNA METHYLATION AND CD5 IN LUPUS B CELLS
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    • "Hypomethylation of IRSs has been investigated extensively and shown to have a role in pathogenesis of complex diseases such as cancer and autoimmune related conditions [27, 33, 34]. The mechanism of how IRS hypomethylation contributes to the pathogenesis of autoimmune diseases is unclear; however, it has been suggested that it could cause aberrant regulation of neighboring genes that have a role in the regulation of the immune response [35, 36], as well as causing nonspecific autoimmune activation via the presence of viral dsRNA or ssRNA transcripts in the circulation [37][38][39]. In this study, we investigated the role of global hypomethylation in BD and found that levels of overall methylation were Table 3: Alu methylation frequency of BD patients and healthy controls. "
    [Show abstract] [Hide abstract] ABSTRACT: Behcet’s Disease (BD) is a multisystem chronic inflammatory disease. The pathology is believed to involve both genetic susceptibility and environmental factors. Hypomethylation leading to activation of interspersed repetitive sequences (IRSs) such as LINE-1 and Alu contributes to the pathologies of autoimmune diseases and cancer. Herein, the epigenetic changes of IRSs in BD were evaluated using combined bisulfite restriction analysis-interspersed repetitive sequences (COBRA-IRS). DNA from neutrophils and peripheral blood mononuclear cells (PBMCs) of BD patients with ocular involvement that were in active or inactive states and healthy controls were used to analyze LINE-1 and Alu methylation levels. For Alu sequences, significant differences were observed in the frequency of C u C u alleles between PBMCs of patients and controls ( p = 0.03 ), and between inactive patients and controls ( p = 0.03 ). For neutrophils, the frequency of C u C u was significantly higher between patients and controls ( p = 0.006 ) and between inactive patients and controls ( p = 0.002 ). The partial methylation ( C u C m + C m C u ) frequencies of Alu between inactive patients and control samples also differed ( p = 0.02 ). No statistically significant differences for LINE-1 were detected. Thus, changes in the methylation level of IRS elements might contribute to the pathogenesis of BD. The role of Alu transcripts in BD should be investigated further.
    Full-text · Article · Mar 2016
    • "When comparing pSS patients and controls, recent studies, including ours, have reported differential methylation profiles in interferon (IFN) regulated genes when testing CD4 þ T cells [6], DNA methylation deregulation patterns in B cells [7], and important global DNA methylation changes in minor salivary gland (MSG) epithelial cells [8]. Interestingly, epigenetic mechanisms are interconnected with pSS genetic risk factors [9] and reversible, thus opening new therapeutic perspectives in pSS and other autoimmune diseases [8] [10] [11]. "
    [Show abstract] [Hide abstract] ABSTRACT: The pathogenesis of primary Sjögren's syndrome (pSS) is complex, in part due to DNA methylation abnormalities. This study was undertaken to evaluate the importance of global DNA methylation (5mC) as determined in minor salivary glands (MSG) from well characterized pSS patients. Twenty-two pSS patients and ten controls were selected, and MSG were stained with anti-5mC, anti-5mC/anti-cytokeratin (KRT)19, or with anti-SSB/La antibodies (Ab). The DNA methylation status at the SSB gene promoter P1 and P1′ was evaluated by methylation-sensitive restriction enzymes (MSRE) coupled with PCR. The effect of the DNA demethylating drug 5 azacytidine (5-Aza) was tested in the human salivary gland (HSG) cell line. In pSS, the reduction of global DNA methylation (5mC) was associated with lymphocyte infiltration, the emergence of 5mClow and KRT19high acini, and the detection of circulating anti-SSB/La Ab, but not with disease activity (ESSDAI). Next, treating HSG cells with 5-Aza was effective in inducing SSB expression. Finally in pSS patients positive for anti-SSB/La Ab, we further observed DNA demethylation at the SSB gene promoter P1 with consequent SSB overexpression at both the transcriptional and protein levels in salivary gland epithelial cells. In conclusion, our results highlight the importance of DNA methylation in the pathophysiology of pSS and to the emergence of anti-SSB/La Ab.
    No preview · Article · Dec 2015 · Journal of Autoimmunity
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    • "Part of this activity may be attributed to the powerful influence of the biotherapies on the epigenetic machinery. In pSS, treating patients with anti-CD20 mAb therapy restores global DNA methylation in SGEC [21], and the utilization of the anti-IL6 receptor mAb itolizumab in SLE B cells repairs the defective Erk/DNMT1 pathway and DNA methylation [16,29]. Citation: Dantec LC, Charras A, Brooks WH, Renaudineau Y (2015) Similarities and Differences of Epigenetic Mechanisms in Lupus and Sjögren's Syndrome. "
    [Show abstract] [Hide abstract] ABSTRACT: Systemic lupus erythematosus (SLE) and primary Sjögren's syndrome are two systemic autoimmune diseases, which are believed to develop when genetically predisposed individuals undergo epigenetic modifications in response to environmental factors. Recent advances in the understanding of the pathophysiology of these two diseases suggest a multi-step process involving environmental factors leading to distinct cell specific deregulation of the epigenetic machinery, and the effect is reinforced in those patients with risk variants mapping to epigenetically-controlled immune regulators. Finally, it was observed that the PKC-delta/Erk/DNMT1 pathway was altered in both diseases and the effects could be reversed thus providing arguments to suggest that therapeutic strategies targeting this pathway would be effective in both diseases.
    Full-text · Article · Oct 2015
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