Anti-integrin αvβ6 antibody as a diagnostic marker for pediatric patients with ulcerative colitis

概要

Gastroenterology 2022;163:1094–1097

Anti–Integrin avb6 Antibody as a Diagnostic Marker for
Pediatric Patients With Ulcerative Colitis

U

RESEARCH LETTERS

lcerative colitis (UC) is a multifactorial chronic disorder with a high prevalence worldwide. UC affects
patients in all age groups; however, pediatric-onset UC is
generally more severe than adult-onset UC.1 To avoid longterm unfavorable outcomes, such as growth failure, early
and proper diagnosis with subsequent treatment is needed
for pediatric UC patients. Gastrointestinal endoscopy is the
criterion standard for a diagnosis of UC, but the procedure is
invasive for pediatric patients, often requiring the use of
general anesthesia. Thus, a non-invasive and disease-specific
marker for diagnosing pediatric UC is strongly required.
We recently identified anti–integrin avb6 antibody in
adult UC patients with very high sensitivity and specificity,
indicating that this autoantibody can be a useful diagnostic
marker for UC in adult patients.2 Here, we examined the
presence and diagnostic value of this antibody in pediatric
patients with inflammatory bowel disease (IBD), including UC.
We enrolled 261 pediatric IBD patients (131 UC, 95
Crohn’s disease [CD], 10 IBD—unclassified [IBD-U], 25 primary immunodeficiency [PID] with IBD), 40 non-IBD patients (13 PID without IBD and 27 non-IBD enterocolitis),
and 28 non-enterocolitis control subjects (Supplementary
Figure 1A). Details of patients and control subjects are
provided in the Supplementary Methods.
A total of 124 of the 131 UC patients (94.7%) had
immunoglobulin (Ig) G antibodies against integrin avb6
based on a cutoff value of the mean plus 3 standard deviations (optical density ¼ 0.2525) for the non-enterocolitis
control subjects. Moreover, these IgG antibodies were
detected in 31/95 (32.6%) CD, 2/10 (20.0%) IBD-U, 2/25
(8.0%) PID with IBD, 0/13 (0%) PID without IBD, and 1/27
(3.7%) non-IBD enterocolitis patients, and in 1/28 (3.6%)
non-enterocolitis control subjects (Figure 1A). The sensitivity and specificity of anti–integrin avb6 IgG autoantibodies in UC patients were, respectively, 94.7% (124/131)
and 81.3% (161/198). On the other hand, the specificity of
anti–integrin avb6 IgG autoantibodies in the diagnosis of UC
against CD was 67.4% (64/95).
Next, we examined the IgG subclasses and autoantibody
isotypes. Among 47 randomly selected antibody-positive UC
patients, 47 (100.0%), 38 (80.9%), 14 (29.8%), 26 (55.3%),
9 (19.1%), 28 (59.6%), and 12 (25.5%) had IgG1, IgG2, IgG3,
IgG4, IgM, IgA, and IgE antibodies, respectively
(Supplementary Figure 1B and C). These data are similar to
those found in the adult patients previously reported with
UC.2 Moreover, the subclasses and isotypes of anti–integrin
avb6 antibodies in patients with CD or PID with IBD were
similar to those of patients with UC (Supplementary
Figure 1B and C)
Previously, we showed that IgG of adult UC patients
blocked integrin avb6–fibronectin binding through an
Arg-Gly-Asp (RGD) tripeptide motif (Supplementary

Figure 2A). Consistently, a solid-phase binding assay
showed that IgG of 45/47 (95.7%) antibody-positive pediatric UC patients blocked integrin avb6–fibronectin binding
(Figure 1B). The blocking activity of IgG was correlated with
the anti–integrin avb6 antibody titers (r ¼ 0.83; P < 0.001)
(Supplementary Figure 2B). Furthermore, RGD-serine (RGDS)
peptides inhibited the binding of IgG to integrin avb6 in a
dose-dependent manner, whereas Arg-Gly-Glu-Ser (RGES)
peptides did not block such binding (Supplementary
Figure 2C). Moreover, IgG of 23/25 (92.0%) CD, 2/2
(100%) IBD-U, and 2/2 (100%) PID with IBD patients with
anti–integrin avb6 antibody inhibited integrin avb6–fibronectin binding (Figure 1B), and RGDS peptides blocked the
binding of IgG of these patients to integrin avb6
(Supplementary Figure 2D and E). In contrast, IgG of non-IBD
enterocolitis patients and non-enterocolitis control subjects
with anti–integrin avb6 antibody neither blocked integrin
avb6–fibronectin binding nor competed with RGDS peptides
on binding to integrin avb6 (Figure 1B and Supplementary
Figure 2E).
Notably, a considerable number of CD patients in this
study (31/95, 32.6%) (Figure 1A) had anti–integrin avb6
antibodies, in contrast to its low number in adult CD patients
(5/71, 7.0%).2 Moreover, these antibodies of CD patients
showed characteristics similar to those of UC patients,
including IgG subclasses, isotypes, blocking activity on
integrin avb6–fibronectin binding, and inhibition of RGDS
peptide binding to integrin avb6. Therefore, we focused on
the clinical characteristics of our pediatric CD patients. We
classified various endoscopic and pathologic findings of the
CD patients into typical UC and typical CD findings, as
described in the Supplementary Methods (Supplementary
Figure 1D).3,4 The average total number of typical UC findings was significantly higher (3.23 vs 0.61; P < 0.001)
whereas the average number of typical CD findings was
significantly lower (2.00 vs 3.02; P < 0.001) in antibodypositive CD patients than in antibody-negative CD patients
(Figure 1C and Supplementary Figure 1E). This result suggests that pediatric CD patients positive for anti–integrin
avb6 antibody have UC-like characteristics. Of note, in pediatric IBD, the diagnosis of UC may change to CD.5 Indeed, 15
of the 95 CD patients in this study had been initially

Abbreviations used in this paper: CD, Crohn’s disease; IBD, inflammatory
bowel disease; IBD-U, inflammatory bowel disease—unclassified; PID,
primary immunodeficiency; UC, ulcerative colitis.
Most current article
© 2022 The Authors. Published by Elsevier Inc. on behalf of the AGA
Institute. This is an open access article under the CC BY license (http://
creativecommons.org/licenses/by/4.0/).
0016-5085
https://doi.org/10.1053/j.gastro.2022.06.026

Anti–Integrin avb6 Antibody in Pediatric UC 1095

October 2022

A

Serum anti-integrin αvβ6
IgG levels (A450)

2.5

2.0

1.5

1.0

0.5

0.0

UC
(n=131)

CD
(n=95)

B

IBD-U
(n=10)

Non-IBD
PID
Non-enterocolitis
PID with IBD
without IBD Enterocolitis
(n=28)
(n=25)
(n=27)
(n=13)

Inhibition of Fibronectin Binding by Patient or Control IgG

80

60

40

20

0

Non-IBD
PID with IBD
Enterocolitis
n=2
n=1

IBD-U
n=2

CD
n=25

UC
n=47

Nonenterocolitis
n=1

with
anti-integrin αvβ6
antibodies

4
3
2
1
0
Positive
n=31

Negative
n=64

4
3
2
1
0
Positive
n=31

Crohn’s disease patients

Negative
n=64

D

without
anti-integrin αvβ6
antibodies

p=0.24

p=1.00

Number of Crohn disease-like findings

5

p<0.001
5

Number of ulcerative colitis-like findings

p<0.001

Number of Crohn’s disease-like findings

Number of ulcerative colitis-like findings

C

5
4
3
2
1
0
Positive Negative
n=2
n=8

Nonenterocolitis
n=13

E

5
4
3
2

F

1
0
Positive Negative
n=2
n=8

IBD-U patients

Figure 1. (A) Serum IgG antibodies against integrin avb6 were detected with the use of an enzyme-linked immunosorbent
assay. The sera of 131 pediatric patients with UC, 95 pediatric patients with CD, 10 patients with IBD-U, 25 patients with PID
with IBD, 13 patients with PID without IBD, 27 patients with non-IBD enterocolitis, and 28 patients without enterocolitis
(control) were examined. The cutoff optical density (OD), defined as the mean plus 3 standard deviations of the sera of nonenterocolitis patients, is indicated by a dashed line. (B) Inhibition of integrin avb6–fibronectin binding by IgG of anti–integrin
avb6 antibody–positive pediatric patients according to solid-phase binding assay. The cutoff OD, defined as the mean plus
3 standard deviations of IgG from the non-enterocolitis control patients, is indicated by a dashed line. (C) Comparison of
endoscopic and pathologic findings between pediatric CD patients with and without anti–integrin avb6 antibodies. We
classified various endoscopic and pathologic findings into typical UC findings or typical CD findings as previously reported
(Supplementary Figure 1D). (D) Comparison of endoscopic and pathologic findings between pediatric IBD-U patients with and
without anti–integrin avb6 antibodies. (E) Colonoscopy of a patient with cytotoxic T-lymphocyte–associated antigen 4 haploinsufficiency showed continuous, circumferential, and diffuse erythema and ulceration in the rectum to the transverse colon
and descending colon. (F) Pathologic images of the biopsies of the same patient showed intraepithelial infiltration of neutrophils and eosinophils (cryptitis, crypt abscess). Hematoxylin and eosin staining; scale bar ¼ 100 mm.

RESEARCH LETTERS

Percent Inhibition of
Fibronectin Binding to Integrin αvβ6

100

1096 Muramoto et al

RESEARCH LETTERS

diagnosed with UC, which was later changed to CD; 13 of
these 15 patients had anti–integrin avb6 antibodies (86.7%).
IBD-U patients with anti–integrin avb6 antibodies had UClike findings, whereas those without anti–integrin avb6 antibodies were less likely to have UC-like findings (Figure 1D).
One of the 2 PID with IBD patients who were positive for
anti–integrin avb6 antibodies (Figure 1A) had cytotoxic Tlymphocyte–associated antigen 4 haploinsufficiency. The
colonoscopy of this patient showed continuous circumferential and diffuse inflammation in the rectum similar to that
found in UC (Figure 1E). Biopsies showed crypt abscesses,
which is also a pathology resembling UC (Figure 1F). The
other patient had activated phosphatidylinositol-4,5bisphosphate 3-kinase catalytic subunit delta syndrome.
Colonoscopy showed lymphoid follicular hyperplasia with
erythema continuous from the lower rectum, which was
previously reported as an early sign of UC.6 These 2 diseases
are characterized by T-cell dysfunction and presence of
various autoantibodies.7,8 Thus, such T-cell dysregulation
might have induced the production of anti–integrin avb6
antibodies along with development of UC-like colitis in the 2
patients.
In conclusion, we found that anti–integrin avb6 antibodies with characteristics similar to those in adult UC patients are present in pediatric UC patients with high
sensitivity. ...

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