respiratory investigation ] (] ] ] ]) ] ] ] –] ] ]Contents lists available at ScienceDirect

Respiratory Investigation
journal homepage: www.elsevier.com/locate/resinv

Original article

Low positive titer of anti-melanoma differentiationassociated gene 5 antibody is not associated with apoor long-term outcome of interstitial lung disease inpatients with dermatomyositis
Satoshi Sakamotoa, Masaki Okamotoa,n,1, Shinjiro Kaiedaa,1,Kiminori Fujimotob, Shuji Nagatab, Masaki Tominagaa,
Masayuki Nakamuraa, Yoshiaki Zaizena, Takashi Nounoa, Takuma Kogaa,
Tomotaka Kawayamaa, Masataka Kuwanac, Hiroaki Idaa, Tomoaki HoshinoaaDivision of Respirology, Neurology, and Rheumatology, Department of Internal Medicine, Kurume University School of
Medicine, Asahi-machi 67, Kurume, Fukuoka 830-0011, Japanb
Department of Radiology and Center for Diagnostic Imaging, Kurume University School of Medicine, Asahi-machi 67,
Kurume, Fukuoka 830-0011, Japanc
Department of Allergy and Rheumatology, Nippon Medical School, Sendagi 1-1-5, Bunkyo-ku, Tokyo 113-8603, Japan

art i cle i nfo

ab st rac t

Article history:

Background: Anti-melanoma differentiation-associated gene 5 antibody (anti-MDA5-Ab) is

Received 28 February 2018

associated with fatal rapidly progressive interstitial lung disease (RP-ILD) in patients with

Received in revised form

dermatomyositis (DM). We attempted to clarify whether anti-MDA5-Ab is associated with

9 July 2018

long-term outcomes in patients with DM-ILD.

Accepted 20 July 2018

Methods: Thirty-six patients with DM-ILD were retrospectively analyzed for their serum antiMDA5-Ab by using an enzyme-linked immunosorbent assay. We analyzed the association
between clinical parameters, including the serum levels of anti-MDA5-Ab and ferritin.

Abbreviations: ARS-Ab,
dermatomyositis; CI,

aminoacyl-transfer RNA synthetase antibody; AUC,

conﬁdence interval; CRP,

predicted; DM-ILD, dermatomyositis-interstitial lung disease; ELISA,
capacity, predicted; HRCT,

area under the curve; CADM,

clinically amyopathic

C-reactive protein; %DLCO, diffusing capacity of the lungs for carbon monoxide,

high-resolution computed tomography; IP,

enzyme-linked immunosorbent assay; %FVC,
immunoprecipitation; KL-6,

LDH,

lactate dehydrogenase; MDA5-Ab,

NSIP,

non-speciﬁc interstitial pneumonia; OP,melanoma differentiation-associated gene 5 antibody; NPV,

ROC,

receiver operating characteristic; RP-ILD, rapidly progressive interstitial lung disease; RR,

organizing pneumonia; OS,overall survival; PPV,

forced vital

Krebs von den Lungen 6;
negative predictive value;

positive predictive value;

relative risk; UIP,

usual interstitial

pneumonianCorresponding author. Fax: þ81 942 31 7703.
E-mail addresses: sakamoto_satoshi@med.kurume-u.ac.jp (S. Sakamoto), okamoto_masaki@med.kurume-u.ac.jp (M. Okamoto),
kaieda@med.kurume-u.ac.jp (S. Kaieda), kimichan@med.kurume-u.ac.jp (K. Fujimoto), sn4735@med.kurume-u.ac.jp (S. Nagata),
tominaga_masaki@med.kurume-u.ac.jp (M. Tominaga), nakamura_masayuki@med.kurume-u.ac.jp (M. Nakamura),zaizen_yoshiaki@med.kurume-u.ac.jp (Y. Zaizen), nouno_takashi@med.kurume-u.ac.jp (T. Nouno),koga_takuma@med.kurume-u.ac.jp (T. Koga), kawayama_tomotaka@med.kurume-u.ac.jp (T. Kawayama),
kuwanam@nms.ac.jp (M. Kuwana), ida@med.kurume-u.ac.jp (H. Ida), hoshino@med.kurume-u.ac.jp (T. Hoshino).
1
Authors contributed equally to this work.
https://doi.org/10.1016/j.resinv.2018.07.007
2212-5345/& 2018 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.

Please cite this article as: Sakamoto S, et al. Low positive titer of anti-melanoma differentiation-associated gene 5 antibody is
not associated with a poor long-term outcome of interstitial lung disease in patients with dermatomyositis. Respiratory
Investigation (2018), https://doi.org/10.1016/j.resinv.2018.07.007

2

respiratory investigation ] (] ] ] ]) ] ] ] –] ] ]Keywords:

Results: Fourteen patients (39%) were positive for anti-MDA5-Ab. The serum levels of anti-Interstitial lung disease

MDA5-Ab and ferritin in 7 patients with acute death were higher than those in the surviving

Autoimmune disease

patients. An “unclassiﬁable pattern” on chest computed tomography and the development of

Anti-melanoma differentiation-

RP-ILD were also prognostic markers. The serum levels of anti-MDA5-Ab and ferritin (cut-off

associated gene 5 antibody

levels, 100 IU/mL and 899 ng/mL, respectively) were markers predictive of acute death, showing

Rapidly progressive interstitial lunggood sensitivity (86% and 83%) and speciﬁcity (97% and 100%). All 7 patients with acute death

diseasedeveloped RP-ILD and were positive for anti-MDA5-Ab, including 6 patients with a high titerDermatomyositis(Z100 IU/mL), whereas only 2 patients (29%) developed RP-ILD among the 7 survivors with a
low titer of anti-MDA5-Ab ( o 100 IU/mL). In contrast, a low positive titer of anti-MDA5-Ab was
not associated with changes in pulmonary function for 2 years.
Conclusions: Although a high serum titer of anti-MDA5-Ab (Z100 IU/mL) is associatedwith acute death via the development of RP-ILD, outcomes in the chronic phase for patientswith a low titer of anti-MDA5-Ab ( o 100 IU/mL) were similar to those of patients withoutanti-MDA5-Ab.
& 2018 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.

1.

Introduction

Interstitial lung disease (ILD) is a common involvement indermatomyositis (DM) [1]. A phenotype of DM patients with
deﬁnite cutaneous manifestations but lacking clinically signiﬁcant muscle involvement is deﬁned as having clinicallyamyopathic DM (CADM). CADM-ILD patients frequently
develop fatal rapidly progressive ILD (RP-ILD) [2–4].
Melanoma differentiation-associated gene 5 (MDA5) is a proteinthat acts as a sensor for RNA viruses in the innate immune system[5]. The anti-CADM-140 antibody (Ab), initially identiﬁed using
protein immunoprecipitation (IP), was later found to recognize
the MDA5 antigen [3]. The fact that anti-MDA5-Ab is associatedwith CADM and/or RP-ILD is of clinical importance [2–4,6–9]. DMILD patients with anti-MDA5-Ab were reported to have a worse
prognosis, compared with anti-aminoacyl-transfer RNA synthetase
antibody (anti-ARS-Ab) [9]. However, we and other groups previously reported that DM-ILD patients with anti-MDA5-Ab who
survived for 3 months from ILD onset or after commencing therapy
did not develop fatal respiratory failure during long-term [8,9]. The
presence of anti-MDA5-Ab is a prognostic marker for developing
fatal RP-ILD, especially during the acute phase; however, the clinicalsigniﬁcance of this autoantibody in the chronic phase of DM-ILD isunclear [3]. Sato et al. suggested that a high anti-MDA5-Ab titermeasured using an enzyme-linked immunosorbent assay (ELISA)
was associated with the development of RP-ILD and a pooroutcome in DM-ILD patients [3,4,6,7]. ELISA showed high sensitivity
and speciﬁcity (85% and 100%) when the cut-off level was set at
8 IU/mL and IP was set as the reference [3]. We attempted to
identify whether a high anti-MDA5-Ab titer in DM-ILD patients wasindeed associated with acute death, and whether a low positive
titer was associated with the long-term outcome.

2.

Patients and methods

2.1.

Study subjects

We retrospectively reviewed the medical records of 36 consecutive DM-ILD patients who had visited our hospital for the ﬁrst

time between January 2007 and December 2015. DM wasdiagnosed according to the Japanese criteria for the diagnosis
of DM (revised in 2015). ILD was diagnosed on the basis of highresolution computed tomography (HRCT) and clinical data.
Patients with other conditions, such as pulmonary infectious
disease or uncontrolled malignant disease, were excluded. The
diagnosis of CADM was based on the diagnostic criteria proposed by Sontheimer [10], i.e., DM patients who had typical DM
rashes but not clinical evidence of muscle symptoms for morethan 6 months. A subset of RP-ILD patients were deﬁned as
those presenting with progressive dyspnea and hypoxemia as
well as worsening of interstitial change on chest radiography
within 1 month from the onset of respiratory symptoms, as
described previously [2]. We set the endpoint for evaluating theoutcome in the acute phase as mortality within 3 months after
commencing therapy, as reported previously [9,11]. Similarly,
we set the endpoint for evaluating the outcome in the chronic
phase as overall survival (OS) and changes in the forced vital
capacity, predicted (%FVC) and diffusing capacity of the lungs
for carbon monoxide, predicted (%DLCO) 6, 12, 18, and 24 months
after commencing therapy in patients for whom pulmonary
function testing were possible.
All procedures performed in studies involving humanparticipants were in accordance with the ethical standardsof the Institutional Review Board of our hospital (Approvaldate: March 31, 2016; Approval number: 15276) and with the2013 Helsinki Declaration. Informed consent to participate inthis study was obtained from all patients.

2.2.

Interpretation of HRCT images

The protocol for pretreatment HRCT is described in the
supplementary materials as reported previously [12]. HRCT
images were interpreted independently by two boardcertiﬁed experienced radiologists blinded to the clinicalinformation. ILD patterns were classiﬁed into deﬁnite usualinterstitial pneumonia (UIP), possible UIP, nonspeciﬁc interstitial pneumonia (NSIP), NSIP with organizing pneumonia(OP), and OP pattern based on the global guideline of idiopathic interstitial pneumonias as described in the

Please cite this article as: Sakamoto S, et al. Low positive titer of anti-melanoma differentiation-associated gene 5 antibody is
not associated with a poor long-term outcome of interstitial lung disease in patients with dermatomyositis. Respiratory
Investigation (2018), https://doi.org/10.1016/j.resinv.2018.07.007

respiratory investigation ] (] ] ] ]) ] ] ] –] ] ]3

Fig. 1 – HRCT features. Representative HRCT images. (A) An image of the lower lung zones of a 59-year-old woman without antiARS-Ab and anti-MDA5-Ab. This was classiﬁed as the NSIP pattern showing characteristic ground-glass opacities with dilated air
bronchogram (or bronchiologram) showing peribronchovascular and subpleural distribution. (B) An image of the lower lung zones ofa 51-year-old woman with anti-Jo-1-Ab and without anti-MDA5-Ab. This was classiﬁed as the NSIP with OP pattern showing
characteristic consolidations and ground-glass opacities with dilated air bronchogram (or bronchiologram) showing
peribronchovascular distribution. (C) An image of the lower lung zones of a 68-year-old woman without anti-MDA5-Ab and antiARS-Ab. This was classiﬁed as the OP pattern showing patchy consolidations without architectural distortion. (D) An image of thelower lung zones of a 50-year-old man with a high titer of anti-MDA5-Ab without anti-ARS-Ab. This was considered to be theunclassiﬁable CT pattern with consolidations and ground-glass opacities showing peripheral and subpleural distribution witharchitectural distortion. HRCT: high-resolution computed tomography; anti-ARS-Ab: anti-aminoacyl-transfer RNA synthetase
antibody; anti-MDA5-Ab: melanoma differentiation-associated gene 5 antibody; NSIP: non-speciﬁc interstitial pneumonia; OP:
organizing pneumonia.

supplementary materials [13,14]. HRCT patterns that could
not be otherwise classiﬁed were denoted as unclassiﬁable CTpatterns, as reported previously [8,13,14]. Representative
HRCT images are shown in Fig. 1.

2.3.

Measurement of autoantibodies

All serum samples were collected before commencing therapy. The anti-MDA5-Ab titer was measured using an ELISA,
as described previously [3]. The cut-off level of the ELISA for
anti-MDA5-Ab was 8 IU/mL [3]. Anti-ARS-Ab was screenedusing the RNA-IP assay, as described previously [15].

2.4.

optimal value with the highest Youden index on a receiver
operating characteristic (ROC) curve generated using logistic
regression [12]. P o 0.05 was considered to represent statisticalsigniﬁcance. All statistical analyses were performed using the
JMP 12.0 program (SAS Institute Japan, Tokyo, Japan).

Statistical analysis

Data were expressed as the median (25th to 75th percentiles of
the interquartile range). Interobserver variations in the ILD
patterns of HRCT were analyzed using the kappa statistic on
the ﬁnal diagnosis made prior to agreement by consensus.
Differences between multiple groups were analyzed appropriately by using the Wilcoxon rank-sum or Fisher's exact tests.
The cut-off levels for various parameters were deﬁned as the3.

Results

3.1.

Characteristics and clinical courses

The characteristics and clinical courses of the analyzed
patients are shown in Table 1. The 36 DM-ILD patients
included 14 (39%) CADM patients, 14 (39%) anti-MDA5-Abpositive patients, and 15 (42%) anti-ARS-Ab-positive patients.
One patient was positive for both anti-ARS-Ab and antiMDA5-Ab, and 8 were negative for both. The antibody subtypes of anti-ARS-Ab-positive patients included anti-PL-7-Ab
in 5 patients, anti-EJ-Ab in 4, anti-Jo-1-Ab in 3, anti-PL-12-Ab
in 2, and anti-KS-Ab in 1. One of the 36 DM-ILD patients had
undergone surgical lung biopsy and was diagnosed as having

Please cite this article as: Sakamoto S, et al. Low positive titer of anti-melanoma differentiation-associated gene 5 antibody is
not associated with a poor long-term outcome of interstitial lung disease in patients with dermatomyositis. Respiratory
Investigation (2018), https://doi.org/10.1016/j.resinv.2018.07.007

4respiratory investigation ] (] ] ] ]) ] ] ] –] ] ]Table 1 – Patient characteristics.
Number of DM-ILD patients
Number of CADM-ILD patients
Age
Gender: Male
SmokerNo. of RP-ILD

36
1459.5 (50.3–68.0)
13 (36%)
11 (31%)14 (39%)Overall survival (days)
Mortality
Within 3 months
Survivor
Non-survivor
Cause of deathBaseline blood data
CRP (mg/dL)
KL-6 (IU/mL)
LDH (IU/L)
Creatinine kinase (IU/L)
Ferritin (ng/mL)

0.51 (0.14–2.3)
856.0 (568.0–1398.0)
372.0 (264.8–462.8)
160.5(62.3–704.3)
357.5 (125.0–802.5)

For all observation period
Survivor
Non-survivor
Cause of death
Therapy (All course)
Corticosteroid

Serum anti-MDA5-Ab and anti-ARS-Ab
With both antibodies
With anti-MDA5-Ab alone
With anti-ARS-Ab alone
Without either antibody
Titer of anti-MDA5-Ab (IU/mL)

1 (3%)
13 (36%)
14 (39%)8 (22%)
1.3 (0.78–73.3)

Pulmonary function test (%)
%FVC
%DLCO

72.3 (64.1–84.1)
60.8 (46.9–80.0)

HRCT pattern
Deﬁnite and possible UIP
NSIP
NSIP with OP
OP
Unclassiﬁable

0
10 (28%)14 (39%)2 (6%)
10 (28%)Immunosuppressant
Tacrolimus
Cyclosporin A
Intravenous cyclophosphamide
Azathioprine
Mycophenolate mofetil

1070.0 (268.8–1543.3)

29 (81%)7 (19%)
RP-ILD, 7

28 (78%)8 (22%)
RP-ILD, 7; AE, 1
34 (94%)30 (83%)28 (78%)13 (36%)9 (25%)
2 (6%)
1 (3%)

DM-ILD: dermatomyositis-interstitial lung disease; CADM: clinically amyopathic DM; RP-ILD: rapidly progressive ILD; CRP: C-reactive protein;
KL-6: Krebs von den Lungen 6; LDH: lactate dehydrogenase; anti-MDA5-Ab: anti-melanoma differentiation-associated gene 5 antibody; antiARS-Ab: anti-aminoacyl-transfer RNA synthetase antibody; %FVC: forced vital capacity, predicted; %DLCO: diffusing capacity of the lungs forcarbon monoxide, predicted; HRCT: high-resolution computed tomography; UIP: usual interstitial pneumonia; NSIP: non-speciﬁc interstitial
pneumonia; OP: organizing pneumonia; AE: acute exacerbation.

NSIP. Fourteen of the 36 patients (39%) were diagnosed ashaving RP-ILD.
Interobserver agreement for the assessment of HRCT patterns was moderate (kappa, 0.60; P o 0.0001). The HRCT
patterns of ILD among the 36 DM-ILD patients, included NSIP
with OP pattern in 14 patients (39%), unclassiﬁable CT pattern in
10 (28%), NSIP pattern in 10 (28%), and OP pattern in 2 (5%). No
patient showed a deﬁnite or possible UIP pattern. The HRCT
images of anti-MDA5-Ab-positive patients showed the following patterns: unclassiﬁable CT pattern in 9 patients (64%), NSIP
with OP pattern in 4 (29%), and NSIP pattern in 1 (7%). The HRCT
images of anti-MDA5-Ab-negative patients showed the following patterns: NSIP with OP pattern in 10 patients (45%), NSIP
pattern in 9 (41%), OP pattern in 2 (9%), and unclassiﬁable CTpattern in 1 (5%). The unclassiﬁable CT pattern was more
frequent in patients positive for anti-MDA5-Ab-positive patients
than in anti-MDA5-Ab-negative patients (P o 0.0001*).
The median observation period from commencing therapy
was 1070 (268.8–1543.3) [range, 2–3446] days. Eight (22%) of
the 36 DM-ILD patients died during the observation period.
Seven patients (19%) died of RP-ILD within 3 months after
commencing therapy (acute phase). The remaining antiMDA5-Ab-negative patient died of respiratory failure due to
ILD after the acute phase. Thirty patients (83%) received
prednisolone in combination with an immunosuppressantand 4 (11%) received prednisolone alone.

3.2.

Predictors of acute death and OS

We compared the clinical data between the 29 survivors and 7
non-survivors at 3 months after commencing therapy to clarify
the predictors of acute death (Table 2). The serum levels of antiMDA5-Ab (P o 0.001) and ferritin (P o 0.001) were higher inpatients with acute death than in the surviving patients. The
unclassiﬁable CT pattern and development of RP-ILD were also
associated with acute death (P o 0.05). The sensitivity, speciﬁcity,
positive and negative predictive values (PPV and NPV, respectively), and results of ROC analyses for distinguishing patientswith acute death from the surviving patients are shown in
Table 3. The optimal cut-off levels of anti-MDA5-Ab and ferritin
based on the ROC curves were 100 IU/mL and 899 ng/mL,
respectively. The accuracy for predicting acute death was higher
for the anti-MDA5-Ab titer (sensitivity, 86%; speciﬁcity, 97%; PPV,86%; and NPV, 97%), ferritin level (sensitivity, 83%; speciﬁcity,100%; PPV, 100%; and NPV, 96%), and development of RP-ILD(sensitivity, 100%; speciﬁcity, 76%; PPV, 50%; and NPV, 100%) thanfor the unclassiﬁable CT pattern (sensitivity, 71%; speciﬁcity, 83%;
PPV, 50%; and NPV, 92%). Among the 14 anti-MDA5-Ab-positive
patients, we compared the clinical data between the 7 survivors
and 7 non-survivors during the acute phase (Table 4). The serum
levels of anti-MDA5-Ab, ferritin, and C-reactive protein and theincidence of RP-ILD were all higher in patients with acute deaththan in the surviving patients (all P o 0.05). Acute death patients

Please cite this article as: Sakamoto S, et al. Low positive titer of anti-melanoma differentiation-associated gene 5 antibody is
not associated with a poor long-term outcome of interstitial lung disease in patients with dermatomyositis. Respiratory
Investigation (2018), https://doi.org/10.1016/j.resinv.2018.07.007

5respiratory investigation ] (] ] ] ]) ] ] ] –] ] ]Table 2 – Clinical data for patients with or without acute death within 3 months after commencing therapy.
Survivorin acute phaseNon-survivor
in acute phase

P value

Number of DM-ILD patients
Number of CADM-ILD patients
Number of RP-ILD patients
Age
Gender; Male
Smoker29
10 (34%)7 (24%)
57.0 (50.0–68.0)
10 (34%)10 (34%)7
4 (57%)
7 (100%)62.0 (53.0–72.0)
3 (43%)
1 (14%)

NSo 0.001***
NS
NS
NS

Baseline blood test
CRP (mg/dL)
KL-6 (IU/mL)
LDH (IU/L)
Creatinine kinase (IU/L)
Ferritin (ng/mL)
Positivity for anti-MDA5-Ab
Titer of anti-MDA5-Ab
High titer ( Z 100 IU/mL)
Low titer ( o 100 IU/mL)

0.50 (0.13–1.7)
1021.0 (535.5–1477.0)
356.0 (258.0–460.5)
155.0 (62.0–753.0)
157.9 (113.5–436.5)
7 (24%)
0.98 (0.77–10.6)
1 (3%)
6 (21%)

1.8 (0.25–2.5)
693.5 (536.0–875.5)
426.0 (276.0–484.0)
191.0 (72.0–395.0)
1370.3 (768.8–2177.8)
7 (100%)311.9 (102.9–603.2)
6 (83%)
1 (17%)

NS
NS
NS
NS
o 0.001***
o 0.001***
o 0.001***

Pulmonary function test (%)
%FVC
%DLCO

72.8 (62.6–86.2)
63.3 (46.9–82.4)

64.7 (64.4–76.0)
52.8 (36.9–57.6)

NS
NS

HRCT patterns
Deﬁnite and possible UIP
NSIP
NSIP with OP
OP
Unclassiﬁable

0
10 (34%)12 (41%)2 (7%)
5 (2%)

00
2 (29%)
0
5 (71%)

o 0.05*

DM-ILD: dermatomyositis-interstitial lung disease; CADM: clinically amyopathic DM; RP-ILD: rapidly progressive ILD; CRP: C-reactive protein;
KL-6: Krebs von den Lungen 6; LDH: lactate dehydrogenase; anti-MDA5-Ab: anti-melanoma differentiation-associated gene 5 antibody; %FVC:
forced vital capacity, predicted; %DLCO: diffusing capacity of the lungs for carbon monoxide, predicted; HRCT: high-resolution computed
tomography; UIP: usual interstitial pneumonia; NSIP: non-speciﬁc interstitial pneumonia; OP: organizing pneumonia; NS: not signiﬁcant. *P o
0.05 and ***P o 0.001 were considered to represent statistical signiﬁcance.

Table 3 – Accuracy of the predictors of acute death in DM-ILD patients.
ROC analysis

Anti-MDA5-Ab
Ferritin
RP-ILD
HRCT patternCut-off level

Sensitivity (%)

Speciﬁcity (%)

PPV (%)NPV (%)AUC (%)

P value

Z100 IU/mL
Z899 ng/mL
RP-ILD
Unclassiﬁable

86
83
100
71

97
100
76
83

86
100
50
50

97
96
100
92

97
95

o 0.01**o 0.05*

DM-ILD: dermatomyositis-interstitial lung disease; ROC: receiver operating characteristic; PPV: positive predictive value; NPV: negative
predictive value; AUC: area under the curve; Anti-MDA5-Ab: anti-melanoma differentiation-associated gene 5 antibody; RP-ILD; rapidly
progressive interstitial lung disease, HRCT; high-resolution computed tomography. *P o 0.05 and **P o 0.01 were considered to represent
statistical signiﬁcance.

were also signiﬁcantly older than the surviving patients (P o0.05). All 7 acute death patients developed RP-ILD and werepositive for anti-MDA5-Ab, including 6 patients with a high titer(Z 100 IU/mL), whereas among the 7 survivors with a low titer ofanti-MDA5-Ab ( o 100 IU/mL), only 2 (29%) developed RP-ILD(Fig. 2; Table 4). Among the 29 survivors, only 1 (3%) had a hightiter of anti-MDA-5-Ab (330.6 IU/mL) and did not develop RP-ILD.
We analyzed the predictors of OS by using the log-rank test.
A higher anti-MDA5-Ab titer (Z 100 IU/mL; relative risk (RR), 26;
95% conﬁdence interval (CI), 5.7–184.2; P o 0.0001), higher
ferritin level (Z 899 ng/mL; RR, 49.6; 95% CI, 7.6–971.5;
P o 0.0001), unclassiﬁable CT pattern (RR, 5.3; 95% CI, 1.3–26.1;

P o 0.05), and development of RP-ILD (RR, 16; 95% CI, 2.8–300.4;
P o 0.001), which were the predictors of acute death, were also
predictors of OS (Fig. 2).

3.3.
Predictors of the outcome of pulmonary function in thechronic phase
We attempted to clarify the outcome of pulmonary function in
7 anti-MDA5-Ab-positive patients who survived for 3 months
after commencing therapy (acute phase). We evaluated theassociation between prognostic factors such as anti-MDA5-Ab
and changes in pulmonary function in the 29 surviving

Please cite this article as: Sakamoto S, et al. Low positive titer of anti-melanoma differentiation-associated gene 5 antibody is
not associated with a poor long-term outcome of interstitial lung disease in patients with dermatomyositis. Respiratory
Investigation (2018), https://doi.org/10.1016/j.resinv.2018.07.007

6respiratory investigation ] (] ] ] ]) ] ] ] –] ] ]Table 4 – Clinical data for 14 patients with anti-MDA5-Ab with or without acute death.
Survivorin acute phaseNon-survivor
in acute phase

P value7
5 (71%)
2 (29%)
44.0 (38.0–54.0)
2 (29%)
1 (14%)

7
4 (57%)
7 (100%)62.0 (53.0–72.0)
3 (43%)
1 (14%)

NSNS
o 0.05*o 0.05*NSNS

0.11 (0.040–0.95)
1060.0 (491.0–1398.0)
320.0 (273.0–453.0)
94.0 (49.0–324.0)
199.0 (82.0–844.0)
71.1 (45.3–86.9)
1 (17%)
6 (83%)

1.8 (0.25–2.5)
693.5 (536.0–875.5)
426.0 (276.0–484.0)
191.0 (72.0–395.0)
1370.3 (768.8–2177.8)
311.9 (102.9–603.2)
6 (83%)
1 (17%)

o 0.05*NSNSNS
o 0.05*o 0.05*

Pulmonary function test (%)
%FVC
%DLCO

77.5 (61.3–86.3)
66.4 (45.6–84.4)

64.7 (64.4–76.0)
52.8 (36.9–57.6)

NS
NS

HRCT patterns
Deﬁnite and possible UIP
NSIP
NSIP with OP
OP
Unclassiﬁable

0
1 (14%)
2 (29%)
0
4 (57%)

00
2 (29%)
0
5 (71%)

NS

Number of patients with DM-ILD
Number of patients with CADM-ILD
Number of patients with RP-ILD
Age
Sex: Male
SmokerBaseline blood
CRP (mg/dL)
KL-6 (IU/mL)
LDH (IU/L)
Creatinine kinase (IU/L)
Ferritin (ng/mL)
Titer of anti-MDA5-Ab (IU/mL)
High titer ( Z 100 IU/mL)
Low titer ( o 100 IU/mL)

MDA5-Ab: melanoma differentiation-associated gene 5 antibody; DM-ILD: dermatomyositis-interstitial lung disease; CADM: clinicallyamyopathic DM; RP-ILD: rapidly progressive ILD; CRP: C-reactive protein; KL-6: Krebs von den Lungen 6; LDH: lactate dehydrogenase; %FVC:
forced vital capacity, predicted; %DLCO: diffusing capacity of the lungs for carbon monoxide, predicted; HRCT: high-resolution computed
tomography; UIP: usual interstitial pneumonia; NSIP: non-speciﬁc interstitial pneumonia; OP: organizing pneumonia; NS: not signiﬁcant.
*P o 0.05 was considered to represent statistical signiﬁcance.

patients after the acute phase. The %FVC at 6, 12, 18, and 24
months after commencing therapy was measured in 19, 20, 15,
and 16 patients, respectively, and %DLCO was measured at thesame time points in 19, 20, 15, and 15 patients, respectively.
Fig. 3 shows the %FVC and %DLCO of patients with and withoutanti-MDA5-Ab after commencing therapy. No signiﬁcant difference was observed in the change in %FVC or %DLCO between
the patients with and without anti-MDA5-Ab at all the measurement time points during the chronic phase. Similarly,
neither the unclassiﬁable CT pattern, high serum ferritin level,nor development of RP-ILD was associated with the changes in%FVC and %DLCO (data not shown).

and ferritin exhibited high sensitivity and speciﬁcity. Sato et al.
suggested that the mean anti-MDA5-Ab titer was signiﬁcantly
higher in survivors (n ¼ 4) than in non-survivors (n ¼ 6) amonganti-MDA5-Ab-positive DM-ILD patients (356.9 vs. 110.3 IU/mL)[4]. The autoantibody titer in survivors with anti-MDA5-Ab was
higher in the previous study than in our study (71.1 IU/mL).
However, both studies equally noted that a high anti-MDA5-Ab
titer (Z 100 IU/mL) was associated with higher mortality.
Analysis involving a larger population will be needed to identify
the optimal cut-off level, as the previous and our study both
involved small cohorts. Moreover, we suggested that patientswith a low titer of anti-MDA5-Ab ( o 100 IU/mL) maintained their
pulmonary function for 2 years similar to anti-MDA5-Ab-

4.

Discussion

We conﬁrmed that a high serum level of anti-MDA5-Ab andferritin and the development of RP-ILD could predict acute deathin DM-ILD patients as reported previously [4,6,7]. A previous
study suggested that the anti-MDA5-Ab titer was signiﬁcantly
higher in anti-MDA5-Ab-positive DM patients with RP-ILD thanin those without RP-ILD [6]. A high anti-MDA5-Ab titer isconsidered to be associated with acute death via the development of RP-ILD. However, we could not prove that a low titer ofanti-MDA5-Ab was a favorable prognostic predictor of acutedeath, because few patients developed RP-ILD. In our study,
the diagnostic accuracy for the serum levels of anti-MDA5-Ab

negative patients. A decrease in FVC or DLCO is a well-known
signiﬁcant risk factor for mortality in idiopathic pulmonaryﬁbrosis patients [16,17]. The maintenance of pulmonary function
is associated with increased survival and quality of life in ILD
patients. Our results suggest that a low titer of anti-MDA5-Ab
was not associated with a poor long-term outcome in DM-ILD
patients. We have previously reported that 4 of 9 polymyositis/
dermatomyositis (PM/DM)-ILD patients with anti-MDA5-Ab diedof RP-ILD, whereas in the 5 remaining survivors positive of antiMDA5-Ab was not associated with the deterioration of pulmonary function for 1 year [9]. Thus, the clinical importance ofanti-MDA5-Ab differs between the acute and chronic phases of
DM-ILD.

Please cite this article as: Sakamoto S, et al. Low positive titer of anti-melanoma differentiation-associated gene 5 antibody is
not associated with a poor long-term outcome of interstitial lung disease in patients with dermatomyositis. Respiratory
Investigation (2018), https://doi.org/10.1016/j.resinv.2018.07.007

respiratory investigation ] (] ] ] ]) ] ] ] –] ] ]7

Fig. 2 – Survival curves. Survival curves obtained using signiﬁcant predictors of overall survival in the log-rank test. A,
positivity for anti-MDA5-Ab with a high (Z 100 IU/mL) or low (o100 IU/mL) titer; B, high serum ferritin level ( Z 899 ng/mL oro 899.9 ng/mL); C, ILD pattern on HRCT; D, development of RP-ILD. Anti-MDA5: anti-melanoma differentiation-associatedgene 5 antibody; ILD: interstitial lung disease; HRCT: high-resolution computed tomography; RP-ILD: rapidly progressiveinterstitial lung disease.

A previous report suggested that intensive immunosuppressive therapy, including corticosteroids, calcineurin inhibitors,
and intravenous cyclophosphamide, was required for DMRPILD patients with anti-MDA5-Ab from the early phase of
disease [18]. However, such therapy may be associated withsevere adverse events, such as infectious diseases. To optimize
the therapeutic strategy, a biomarker for predicting acute death
is required. A high serum anti-MDA5-Ab titer (Z100 IU/mL) as
well as a high ferritin level may have some potential as
biomarkers to identify patients who require intensive immunosuppressive therapy in the acute phase. Conversely, thepresence of this autoantibody at a low titer ( o100 IU/mL)
may not affect the therapeutic strategy used during the chronic
phase. Although anti-MDA5-Ab is a useful prognostic biomarker, it should be noted that its clinical importance differs basedon the serum titer.
In anti-MDA5-Ab-positive-DM-ILD patients, the radiological ILD pattern tended to be the unclassiﬁable CT pattern,which was predominant over the NSIP with or without OP
pattern, as reported previously [8]. Moreover, theunclassiﬁable CT pattern was associated with acute death.
In contrast, we and other groups have reported anti-ARS-Abpositive patients exhibited the radiological NSIP with orwithout OP pattern [9,19]. The NSIP with or without OP
pattern is reportedly associated with a more favorable
response to immunosuppressive therapy than other ILD
subtypes such as UIP [14]. The HRCT ﬁndings in antiMDA5-Ab-positive patients were distinct from those withoutanti-MDA5-Ab, including anti-ARS-Ab-positive patients.
Thus, in addition to serological data, radiological ﬁndings
appear valuable for predicting the prognosis of DM-ILD.
The present study had three limitations. First, because it
was a single-center study, it involved only a small patient
cohort. Second, we were unable to follow changes in the antiMDA5-Ab titer because the number of serum samples collected was insufﬁcient. However, our study suggested earlybiomarkers capable of predicting the outcome of DM-ILD.
Third, the change in pulmonary function could not bemeasured in all of the study subjects after commencing
therapy. This may have affected our results. However, wePlease cite this article as: Sakamoto S, et al. Low positive titer of anti-melanoma differentiation-associated gene 5 antibody is
not associated with a poor long-term outcome of interstitial lung disease in patients with dermatomyositis. Respiratory
Investigation (2018), https://doi.org/10.1016/j.resinv.2018.07.007

8respiratory investigation ] (] ] ] ]) ] ] ] –] ] ]Acknowledgements
We thank Yuka Okazaki (Nippon Medical School, Tokyo,
Japan) for technical assistance.

Conﬂict of interest
None.

Appendix A.

Supporting information

Supplementary data associated with this article can be foundin the online version at https://doi.org/10.1016/j.resinv.2018.
07.007.

r e f e r e n c e s

Fig. 3 – Changes in forced vital capacity, predicted (%FVC)
and diffusing capacity of the lung for carbon monoxide,
predicted (%DLCO) determined every 6 months. Changes inpulmonary function parameters at 6, 12, 18, and 24 months
after commencing therapy in groups positive and negative
for anti-MDA5-Ab (A, %FVC, B, %DLCO). Anti-MDA5-Ab: antimelanoma differentiation-associated gene 5 antibody; NS:
not signiﬁcant.

believe that our results are valid, because no signiﬁcantdifference was observed in the pulmonary function measurements between patients with and without the various prognostic factors.

5.

Conclusions

Although a high serum titer of anti-MDA5-Ab ( Z 100
IU/mL) is associated with acute death via the developmentof RP-ILD, patients with a low titer of anti-MDA5-Ab( o 100 IU/mL) showed an outcome in the chronic phasesimilar to that of anti-MDA5-Ab-negative-patients. AntiMDA5-Ab is a useful biomarker that facilitates theidentiﬁcation of DM-ILD patients who require intensive
immunosuppressive therapy in the acute phase, but does
not affect the therapeutic strategy applied during thechronic phase.

[1] Fathi M, Dastmalchi M, Rasmussen E, Lundberg IE, Tornling
G. Interstitial lung disease, a common manifestation of
newly diagnosed polymyositis and dermatomyositis. Ann
Rheum Dis 2004;63:297–301.
[2] Sato S, Hirakata M, Kuwana M, Suwa A, Inada S, Mimori T, et al.
Autoantibodies to a 140-kd polypeptide, CADM-140, in Japanesepatients with clinically amyopathic dermatomyositis. Arthritis
Rheum 2005;52:1571–6.
[3] Sato S, Hoshino K, Satoh T, Fujita T, Kawakami Y, Fujita T, et al.
RNA helicase encoded by melanoma differentiation–associatedgene 5 is a major autoantigen in patients with clinicallyamyopathic dermatomyositis: association with rapidly progressive interstitial lung disease. Arthritis Rheum
2009;60:2193–200.
[4] Sato S, Kuwana M, Fujita T, Suzuki Y. Anti-CADM-140/MDA5
autoantibody titer correlates with disease activity and predicts disease outcome in patients with dermatomyositis andrapidly progressive interstitial lung disease. Mod Rheumatol
2013;23:496–502.
[5] Kato H, Takeuchi O, Mikamo-Satoh E, Hirai R, Kawai T,
Matsushita K, et al. Length-dependent recognition of
double-stranded ribonucleic acids by retinoic acid-inducible
gene-I and melanoma differentiation-associated gene 5.
J Exp Med 2008;205:1601–10.
[6] Sato S, Murakami A, Kuwajima A, Takehara K, Mimori T,
Kawakami A, et al. Clinical utility of an enzyme-linked
immunosorbent assay for detecting anti-melanoma differentiation-associated gene 5 autoantibodies. PLoS One
2016;11:e0154285.
[7] Gono T, Sato S, Kawaguchi Y, Kuwana M, Hanaoka M,
Katsumata Y, et al. Anti-MDA5 antibody, ferritin and IL-18
are useful for the evaluation of response to treatment ininterstitial lung disease with anti-MDA5 antibody-positive
dermatomyositis. Rheumatology 2012;51:1563–70.
[8] Hozumi H, Fujisawa T, Nakashima R, Johkoh T, Sumikawa H,
Murakami A, et al. Comprehensive assessment of myositisspecific autoantibodies in polymyositis/dermatomyositisassociated interstitial lung disease. Respir Med
2016;121:91–9.
[9] Yoshida N, Okamoto M, Kaieda S, Fujimoto K, Ebata T, Tajiri
M, et al. Association of anti-aminoacyl-transfer RNA
synthetase antibody and anti-melanoma differentiationassociated gene 5 antibody with the therapeutic response ofPlease cite this article as: Sakamoto S, et al. Low positive titer of anti-melanoma differentiation-associated gene 5 antibody is
not associated with a poor long-term outcome of interstitial lung disease in patients with dermatomyositis. Respiratory
Investigation (2018), https://doi.org/10.1016/j.resinv.2018.07.007

respiratory investigation ] (] ] ] ]) ] ] ] –] ] ]polymyositis/dermatomyositis-associated interstitial lungdisease. Respir Investig 2017;55:24–32.
[10] Sontheimer RD. Would a new name hasten the acceptance ofamyopathic dermatomyositis (dermatomyositis sine myositis) as a distinctive subset within the idiopathic inflammatory dermatomyopathies spectrum of clinical illness? J Am
Acad Dermatol 2002;46:626–36.
[11] Kataoka K, Taniguchi H, Kondoh Y, Nishiyama O, Kimura T,
Matsuda T, et al. Recombinant human thrombomodulin in
acute exacerbation of idiopathic pulmonary fibrosis. Chest
2015;148:436–43.
[12] Tajiri M, Okamoto M, Fujimoto K, Johkoh T, Ono J, Tominaga
M, et al. Serum level of periostin can predict long-term
outcome of idiopathic pulmonary fibrosis. Respir Investig
2015;53:73–81.
[13] Raghu G, Collard HR, Egan JJ, Martinez FJ, Behr J, Brown KK, etal. An official ATS/ERS/JRS/ALAT statement: idiopathic pulmonary fibrosis: evidence-based guidelines for diagnosis andmanagement. Am J Respir Crit Care Med 2011;183:788–824.
[14] Travis WD, Costabel U, Hansell DM, King Jr TE, Lynch DA,
Nicholson AG, et al. An official American Thoracic Society/
European Respiratory Society statement: update of theinternational multidisciplinary classification of the9

idiopathic interstitial pneumonias. Am J Respir Crit Care Med
2013;188:733–48.
[15] Forman MS, Nakamura M, Mimori T, Gelpi C, Hardin JA.
Detection of antibodies to small nuclear ribonucleoproteinsand small cytoplasmic ribonucleoproteins using unlabeledcell extracts. Arthritis Rheum 1985;28:1356–61.
[16] Flaherty KR, Mumford JA, Murray S, Kazerooni EA, Gross BH,
Colby TV, et al. Prognostic implications of physiologic andradiographic changes in idiopathic interstitial pneumonia.
Am J Respir Crit Care Med 2003;168:543–8.
[17] Latsi PI, du Bois RM, Nicholson AG, Colby TV, Bisirtzoglou D,
Nikolakopoulou A, et al. Fibrotic idiopathic interstitial
pneumonia: the prognostic value of longitudinal functional
trends. Am J Respir Crit Care Med 2003;168:531–7.
[18] Nakashima R, Hosono Y, Mimori T. Clinical significance andnew detection system of autoantibodies in myositis withinterstitial lung disease. Lupus 2016;25:925–33.
[19] Debray MP, Borie R, Revel MP, Naccache JM, Khalil A, ToperC, et al. Interstitial lung disease in anti-synthetase syndrome: initial and follow-up CT findings. Eur J Radiol
2015;8:516–23.

Please cite this article as: Sakamoto S, et al. Low positive titer of anti-melanoma differentiation-associated gene 5 antibody is
not associated with a poor long-term outcome of interstitial lung disease in patients with dermatomyositis. Respiratory
Investigation (2018), https://doi.org/10.1016/j.resinv.2018.07.007