Introduction
Irritable bowel syndrome (IBS) is a clinical condition characterized by changes in
bowel movement frequency and consistency and abdominal pain. IBS affects 10–20 % of
the population worldwide [1]. Currently, IBS diagnosis is based on the Rome IV criteria, derived from a consensus
process by a multinational group of experts [2], which have a low sensitivity of 62.7 % [3]. According to these criteria, IBS is diagnosed based on recurrent abdominal pain
related to defecation or in association with a change in stool frequency or form.
Based on the Rome IV criteria, IBS is classified into four subtypes according to patients’
reports of the proportion of time they have hard or lumpy stools versus loose or watery
stools [2].
IBS has traditionally been considered to be a chronic functional gastrointestinal
disorder [4], as there are no reliable biomarkers or specific endoscopic findings that can discriminate
affected patients from healthy controls [5]
[6]. Indeed, validation of the Rome IV diagnostic questionnaire for adults failed to
produce high diagnostic sensitivity for an objective diagnosis of IBS in affected
adults. The current modality test failed to produce an objective measured and evaluated
indicator for the diagnosis of IBS [3].
Numerous studies have identified measurable components of IBS that suggest that it
is an organic disorder. Altered gastrointestinal motility, visceral hypersensitivity,
postinfectious reactivity, brain-gut interactions, altered fecal microflora, bacterial
overgrowth, food sensitivity, carbohydrate malabsorption, and intestinal inflammation,
however, have all been implicated in IBS pathogenesis [7]. Increased numbers of inflammatory cells and levels of cytokines in the colonic
mucosa have also been detected in patients with IBS, especially those with diarrhea-predominant
IBS and postinfectious IBS [7]
[8]. These findings support the hypothesis that immune activation may have a role in
IBS pathogenesis, which has resulted in several studies exploring the use of inflammatory
and immunological markers for the diagnosis of IBS. Specifically, impaired intestinal
barrier function (gut permeability) and elevated inflammatory marker expression have
been described and correlated with IBS severity [9]. Similarly, the quantification and distribution of colonic immune cells and immune
activity have been studied by measuring cytokine levels and serum biomarker expression;
however, these measures can only be evaluated using quantitative assessments [5]
[10]
[11]
[12]
[13].
The mechanisms underlying IBS pathophysiology are complex and multifactorial. Several
studies have suggested low grade colonic inflammation as an initiator of gut dysfunction
in affected patients [11]
[14]. Other studies have shown an increase in the levels of inflammatory cytokines and
oxidative stress serum biomarker levels in patients with IBS, suggesting a systematic
inflammatory response [5]
[6]. A recent meta-analysis described an increase in the number of mucosal immune cells
in colonic biopsies of patients with IBS, specifically mast cells and CD3 + T cells
[12], suggesting that low grade colonic inflammation plays a role in IBS pathophysiology
[5]
[6]
[12]
[13].
IBS is currently considered to be a diagnosis of exclusion; however, a positive diagnosis
approach using an accurate diagnostic test is promising. White-light endoscopy can
detect macroscopic features of inflammation, but its capacity to assess inflammation,
identify specific findings and reliably diagnose IBS is low, and it is unable to detect
specific signs of IBS [15]. Instead, endoscopy is performed to exclude other causes of the patients’ symptoms.
Novel techniques, such as digital chromoendoscopy and optical magnification, cannot
provide sufficient magnification to detect microinflammation. Probe-based confocal
laser endomicroscopy (pCLE) combines real-time endoscopic and histologic evaluations
with a high magnification (1000-fold magnification) [16]. Using this technique, endoscopists can visualize cellular details in vivo at a
level comparable to that of conventional histologic slides. Furthermore, when fluorescein
is used as a contrast agent, pCLE can detect the epithelial gap density of the intestinal
epithelium, which is a marker of epithelial cell extrusion [17]. pCLE is, therefore, considered to be a reliable technique for in vivo, real-time
assessment of intestinal barrier function and inflammatory activity [18]. In addition, pCLE provides improved mucosal analysis and biopsy targeting compared
to conventional methods (colonoscopy with random biopsy samples) that yield a limited
number of biopsies for histopathologic analysis, and have a risk of false negative
results.
pCLE has been used in patients with IBS and suspected food intolerance. With this
approach, increased epithelial gap density in the small bowel, immediate breaks, increased
intervillous spaces, and increased intraepithelial lymphocytes in the mucosa have
been associated with IBS [17]
[19]. There are currently no published reports detailing pCLE findings in the colonic
mucosa of patients with IBS.
The aims of the present study were (1) to determine the presence of colorectal mucosa
microinflammation in vivo via pCLE and histologic evaluation in patients with IBS,
and (2) to determine whether pCLE is sufficiently sensitive and specific to differentiate
IBS from healthy patients.
Material and methods
Study design
This prospective, controlled, nonrandomized and single-blind diagnostic trial was
conducted at the Instituto Ecuatoriano de Enfermedades Digestivas (IECED) and registered
at ClinicalTrials.gov under code NCT02651532. Patients were enrolled from January
2016 to March 2017.
The study protocol was reviewed and approved by the Institutional Review Board and
Human Ethics Committee of our institution under protocol number ENE12016. The study
was conducted in accordance with the Declaration of Helsinki. Informed and written
consent was obtained from all participants. All authors had access to the study data
and reviewed and approved the final manuscript.
Population selection
Consecutive patients ≥ 18 years of age were invited to participate in the study and
were assigned to one of two groups: the study group or the control group. The study
group consisted of patients with an IBS diagnosis given within the past 12 months,
based on the Rome IV criteria [3]. Recurrent abdominal pain, on average, at least 1 day/week in the last 3 months,
associated with two or more of the following criteria: related to defecation, associated
with a change in the frequency of stool, associated with a change in the form (appearance)
of stool. The criteria must have been fulfilled for the last 3 months with symptom
onset at least 6 months before diagnosis.
Symptoms had to be present > 25 % of the time; symptoms were evaluated by means of
daily diaries that were completed for 15 days and included a stool consistency rating
using the Bristol stool form score [20]. The control group consisted of individuals without any digestive complaint but
who were undergoing a colonoscopy exam most commonly for colorectal cancer screening.
Control subjects had no macroscopic lesions visible by endoscopic examination, including
polyps, ulcerations, or macroscopic signs of inflammation.
All medical records, imaging data, and laboratory tests were reviewed by three gastroenterologists
to exclude potential misdiagnoses.
Inclusion criteria
The inclusion criteria were as follows: inflammatory serum biomarkers (C-reactive
protein and erythrocyte sedimentation rate) within normal limits, normal imaging tests
(endoscopic and abdominal ultrasonography evaluation), negative serology for celiac
disease, negative serial stool test examination for parasitic infection and culture,
normal breath test in patients with suspected lactose intolerance or bacterial overgrowth,
and a normal level of serum thyroid-stimulating hormone.
Exclusion criteria
Patients were excluded if they were pregnant or nursing, had a history of postinfectious
IBS, lymphocytic or collagenous colitis, psychiatric comorbidities such as major depressive
disorder or bipolar affective disorder, inflammatory bowel disease, colonic obstruction
or resection, allergy to fluorescein, an inadequate quality of bowel preparation (Boston
bowel preparation scale score < 2 in any segment of the colon), or had been administered
nonsteroidal anti-inflammatory drugs, acetylsalicylic acid, herbals, corticosteroids
or antibiotics within the past 12 months. Included subjects denied smoking and alcohol
consumption.
Colonoscopy with pCLE
All participants underwent colonoscopy examination performed by two endoscopists (CR-M,
MV); both operators had completed training for pCLE image interpretation with a score ≥ 9
and had performed more than 100 pCLE procedures before the study. These operators
were blinded to the patient medical records and group allocation. Bowel preparation
was performed using polyethylene glycol-electrolyte solution for all participants.
After deep sedation by intravenous propofol administration, a standard colonoscopy
using a high definition scope with white light (Pentax EC-3890LZi, Tokyo, Japan) was
performed. Care was given to avoid damaging the epithelium during mucosal inspection.
Patients were intravenously injected with 5 mL of 10 % fluorescein (BioGlo, Sofar
Productos, Bogota, Colombia), and then pCLE was performed in single endoscopic view
in each anatomic colon segment using a ColoFlex probe (Cellvizio; Mauna Kea Technology,
Paris, France) through the accessory channel of the scope. The probe was gently placed
in contact with the mucosa to avoid trauma. Finally, a targeted biopsy of each colon
segment evaluated by the pCLE probe was performed. A total of six biopsies per patient
were obtained, one for each colonic segment (cecum, ascending colon, transverse colon,
descending colon, sigmoid colon, and rectum). All mucosal biopsies were taken immediately
after removal of the pCLE probe and as close as possible to the pCLE imaging site.
pCLE inflammation criteria
Altered crypt architecture (difference in shape, size, and distribution of crypts),
increased epithelial gaps (increased distance between crypts) with fluorescein leaks
into the crypt lumen, and dilated and prominent branching vessels detected by pCLE
were considered to indicate inflammation [18].
Correlation between pCLE and histological findings
The Geboes scale was used to evaluate the histological aspects of the segments evaluated
initially via pCLE [21]. The Geboes scale is composed of six grades: grade 0 exhibits structural changes,
grade 1 chronic inflammation with cell infiltrate, grade 2 a lamina propria with neutrophils
and eosinophils, grade 3 neutrophils in the epithelium, grade 4 crypt destruction,
and grade 5 erosions or ulcers. All histologic samples were evaluated by a single
pathologist who was blinded to the clinical and endoscopic information.
Statistical analyses
Sample size calculation
Using a 1 % margin of error (type I and type II errors), we estimated that 37 participants
in each group would be needed to detect inflammation in the colon of IBS patients.
Prevalences of microinflammatory changes of 62.5 % and 11.1 % in the IBS and control
groups, respectively, were estimated as previously described [17].
Data analysis
Continuous and categorical variables were compared by Student’s t test, Pearson chi-squared test or Fisher’s exact test, as appropriate. The relationship
between the study group and the presence of microinflammation on pCLE was determined
using the odds ratio (OR) per colon segment. The overall diagnostic accuracy of pCLE
for the diagnosis of IBS was determined by the sensitivity, specificity, positive
predictive value (PPV), negative predictive value (NPV), and an off-line observed
interrater agreement (Cohen’s kappa). A P value < 0.05 was considered statistically significant. Data analysis was performed
using R version 3.4.3 (R Foundation for Statistical Computing, Vienna, Austria).
Results
We recruited 93 patients, of whom 37 were enrolled in the IBS group and 37 were enrolled
in the control group; 19 patients were excluded across both groups due to inadequate
bowel preparation, positive stool cultures or the presence of lesions during white
light colonoscopy. The mean age of the IBS patients was 50.62 ± 15.9 years, and there
were 29 (78.4 %) females, as IBS is more common in women. The mean age of the control
patients was 55.51 ± 12.3 years, with 19 (51.44 %) females. The IBS group included
11 (29.7 %) cases of diarrhea-predominant IBS, 21 (56.8 %) cases of constipation-predominant
IBS and five (13.5 %) cases of alternating constipation and diarrhea IBS. A Boston
Bowel Preparation Scale score of 8 (interquartile range 6–9) was attributed to both
the study group and control group. No adverse events occurred during the study.
Inflammatory lesions detected during pCLE
We detected a statistically significant difference in the number of inflammatory changes
between cases and controls by pCLE and histological evaluation in all colon segments
and the rectum. A significantly higher number of pCLE images with inflammatory lesions
were obtained in the IBS group than in the control group (OR 6.28; 4.14–9.52; P < 0.001). The percentage of pCLE images with inflammatory lesions detected in each
colon segment was 65.8 % in the IBS group. Twenty patients in the IBS group exhibited
microinflammation via pCLE in three or more colon segments, which reflects a more
severe clinical condition. In the control group, the percentage of pCLE images with
inflammatory lesions detected in each colon segment was 23.4 %. One control subject
exhibited microinflammation in three or more colon segments. In patients with IBS,
most lesions occurred in the ascending colon, and in control subjects, most lesions
occurred in the cecum. The inflammatory lesions found during pCLE in each colon segment
are summarized in [Table 1]. Subjects with a healthy colonic mucosa exhibited dark goblet cells, a round crypt
structure with regular and narrow vessels surrounding the crypts. IBS patients exhibited
cellular infiltration with fluorescein leaks into the crypt lumen; differences in
the shapes, sizes, and distribution of the crypts; a large distance between crypts
and focal crypt distribution; and mild-to-moderate increases in capillaries. [Fig. 1] shows the endoscopic, pCLE, and histological findings of a patient with constipation-predominant
IBS. These data indicate that organic alterations in patients with IBS can be detected
by pCLE and open a discussion about the functional versus organic nature of IBS.
Table 1
Number of colonic segments with inflammatory lesions detected during pCLE evaluation.
|
Cases (n = 37)
|
Control (n = 37)
|
Total (n = 74)
|
P value
|
|
Cecum, n (%)
|
25 (67.6)
|
12 (32.4)
|
37 (50.0)
|
0.003
|
|
Ascending colon, n (%)
|
28 (75.7)
|
7 (18.9)
|
35 (47.3)
|
< 0.001
|
|
Transverse colon, n (%)
|
23 (62.2)
|
10 (27.0)
|
33 (44.6)
|
0.002
|
|
Descending colon, n (%)
|
18 (48.6)
|
6 (16.2)
|
24 (32.4)
|
0.003
|
|
Sigmoid colon, n (%)
|
26 (70.3)
|
8 (21.6)
|
34 (45.9)
|
< 0.001
|
|
Rectum, n (%)
|
26 (70.3)
|
9 (24.3)
|
35 (47.3)
|
< 0.001
|
|
Total
|
146/222 (65.8)
|
52/222 (23.4)
|
198/444 (44.6)
|
< 0.001
|
pCLE, probe-confocal laser endomicroscopy.
Fig. 1 pCLE inflammation criteria. a Cellular infiltration present (arrows), fluorescein leaks into the crypt lumen (ellipse).
b Differences in shapes, sizes and distribution of crypts (ellipses); increased distance
between crypts, focal crypt distribution (arrows). c Mild to moderate increase in capillaries, dilated and distorted capillaries (dashed
lines).
pCLE target biopsy analysis
All mucosal biopsies were taken immediately after removal of the pCLE probe and as
close as possible to the pCLE imaging site. We obtained 444 biopsies from the 74 patients
included in the study. Pathology results indicated that one patient from the IBS group
had eosinophilic colitis, and no patient met the criteria for either ulcerative colitis
or lymphocytic colitis. In a sub-analysis of cell infiltrate among different IBS phenotypes
(37 IBS patients, 11/37 diarrhea-predominant IBS, 21/37 constipation-predominant IBS,
and 5/37 alternating IBS), we found no statistically significant difference (Supplementary table 1).
Histologic findings by the Geboes scale
Next, the histological findings were assigned a score according to the Geboes scale
in all evaluated segments. Here, we found that a Geboes score > 0 was more frequently
found in the IBS group than in the control group (60.8 % vs. 27.5 %; P < 0.001) ([Table 2]). Eighteen IBS patients exhibited a Geboes score > 0 in three or more colon segments.
Three control subjects exhibited a Geboes score > 0 in three or more colon segments.
We found a statistically significant difference in the distribution of the Geboes
scores between cases and control groups in the cecum, ascending colon, sigmoid colon,
and rectum expressed by the number of patients (P = 0.048, P = 0.003, P = 0.001, and P = 0.046, respectively). [Fig. 2] represents the distribution of the assigned Geboes score in each study group expressed
by the number of patients and colon segment. However, in a sub-analysis of pCLE inflammatory
findings among each Geboes score in the IBS and control group, we found no statistically
significant differences (Supplementary table 2).
Table 2
Number of colonic segments with inflammatory lesions detected during histological
evaluation according to the Geboes scale (> 0).
|
Cases (n = 37)
|
Control (n = 37)
|
P value
|
|
Cecum, n (%)
|
26 (70.27)
|
14 (37.83)
|
0.005
|
|
Ascending colon, n (%)
|
28 (75.67)
|
11 (29.72)
|
< 0.001
|
|
Transverse colon, n (%)
|
22 (59.45)
|
13 (35.13)
|
0.036
|
|
Descending colon, n (%)
|
15 (40.54)
|
8 (21.62)
|
0.079
|
|
Sigmoid colon, n (%)
|
26 (70.27)
|
8 (21.62)
|
< 001
|
|
Rectum, n (%)
|
18 (48.64)
|
7 (18.91)
|
0.007
|
|
Total
|
135/222 (60.8)
|
61/222 (27.5)
|
< 0.001
|
Fig. 2 Histological findings compatible with inflammation in accordance with the Geboes scale
in each colorectal segment.
Overall diagnostic accuracy of the pCLE inflammatory findings
When considering a target biopsy of a segment as the gold standard, the inflammatory
findings detected during pCLE colonoscopy in patients with IBS showed a sensitivity,
specificity, PPV, NPV, and observed and interrater agreement of 86.7 %, 88.7 %, 85.9 %,
89.4 %, 87.8 %, and 75.4 %, respectively ([Table 3]). There were no statistically significant differences in the pooled sensitivity
(P = 0.4680) or specificity (P = 0.1427) for each colon segment or the rectum. [Table 4] shows the overall diagnostic accuracy of the pCLE inflammatory findings per IBS
patient; biopsies were considered positive for inflammation when the Geboes score
was greater than zero. An individual was considered positive for inflammation when
more than three of the six biopsies had a Geboes score > 0.
Table 3
Overall diagnostic accuracy of pCLE in detecting inflammatory changes in the 37 patients
with IBS when considering target biopsy as the gold standard.
|
Cecum
|
Ascending colon
|
Transverse colon
|
Descending colon
|
Sigmoid colon
|
Rectum
|
Total
|
|
Sensitivity, % (range)
|
87.5 (73.2–95.8)
|
82.1 (66.5–92.5)
|
88.6 (73.3–96.8)
|
78.3 (56.3–92.5)
|
88.2 (72.6–96.7)
|
96.0 (79.7–99.9)
|
86.7 (81.2–91,2)
|
|
Specificity, % (range)
|
94.1 (80.3–99.3)
|
91.4 (76.9–98.2)
|
94.9 (82.7–99.4)
|
88.2 (76.1–5.6)
|
90.0 (76.3–97.2)
|
77.6 (63.4–88.2)
|
88.7 (84.1–92.4)
|
|
PPV, % (range)
|
94.6 (81.9–98.5)
|
91.4 (78.2–97.0)
|
93.9 (80.0–98.4)
|
75.0 (59.7–86.2)
|
88.2 (76.4–95.0)
|
68.6 (56.3–78.7)
|
85.9 (81.0–89.6)
|
|
NPV, % (range)
|
86.5 (73.7–93.6)
|
82.1 (69.9–90.0)
|
90.2 (78.6–95.9)
|
90.0 (80.5–95.2)
|
90.0 (78.1–95.8)
|
97.4 (84.7–99.6)
|
89.4 (85.5–92.4)
|
|
Observed agreement
|
90.5
|
86.5
|
91.9
|
91.9
|
89.2
|
83.8
|
87.8
|
|
Inter-rater agreement
|
81.1 (67.8–94.4)
|
73.1 (57.6–88.5)
|
83.7 (71.2–96.2)
|
65.7 (47.2–84.2)
|
78.2 (64.0–92.5)
|
67.0 (50.6–83.4)
|
75.4 (69.2–81.5)
|
IBS, irritable bowel syndrome; pCLE, probe-confocal laser endomicroscopy; PPV, positive
predictive value; NPV, negative predictive value.
Table 4
Overall diagnostic accuracy of pCLE for the inflammatory findings in the IBS group
(n = 37) per patient when considering p-CLE target biopsy as the gold standard (%,95 %
CI).
|
Cecum[1]
|
Right colon[1]
|
Transverse colon[1]
|
Left colon[1]
|
Sigmoid[1]
|
Rectum[1]
|
Total[2]
|
|
Sensitivity
|
88 (73–96)
|
82 (66–92)
|
89 (73–97)
|
78 (56–93)
|
88 (73–97)
|
96 (80–100)
|
76 (53–92)
|
|
Specificity
|
94 (80–99)
|
91 (77–98)
|
95 (83–99)
|
88 (76–96)
|
90 (76–97)
|
78 (63–88)
|
91 (79–97)
|
|
PPV
|
95 (82–99)
|
91 (77–98)
|
94 (80–99)
|
75 (53–90)
|
88 (73–97)
|
69 (51–83)
|
76 (53–92)
|
|
NPV
|
86 (71–95)
|
82 (66–92)
|
90 (77–97)
|
90 (78–97)
|
90 (76–97)
|
97 (87–100)
|
91 (79–97)
|
|
Observed agreement
|
90.5 %
|
86.4 %
|
91.9 %
|
85.1 %
|
89.1 %
|
83.7 %
|
86.5 %
|
|
Inter-rater agreement
|
81.1 % (P < 0.001)
|
73.1 % (P < 0.001)
|
83.7 % (P < 0.001)
|
65.7 % (P < 0.001)
|
78.2 % (P < 0.001)
|
67.0 % (P < 0.001)
|
66.8 %
(P < 0.001)
|
CI, confidence interval; IBS, irritable bowel syndrome; pCLE, probe-confocal laser
endomicroscopy.
1 A biopsy was positive for inflammation when Geboes > 0.
2 A case was positive for inflammation when > 3/6 biopsies were Geboes > 0.
Discussion
We aimed to determine the presence of colorectal mucosa microinflammation in vivo
via pCLE and histological evaluation in patients with IBS and to determine whether
pCLE is sufficiently sensitive and specific to differentiate IBS from healthy patients.
In the present study, we found that pCLE and histologic signs of microinflammation,
such as an altered crypt architecture, increased epithelial gaps with fluorescein
leaks, and dilated and prominent branching vessels, are sufficiently sensitive and
specific for differentiating healthy individuals from patients with IBS.
Compared to the control group, we detected a significant increase in the number of
pCLE inflammatory findings in patients with IBS, equating to an approximately six-fold
higher prevalence of microinflammation compared to healthy individuals (OR 6.28; 4.14–9.52;
P < 0.001). The ascending and sigmoid colons and the rectum exhibited the greatest
number of inflammatory lesions. Inflammatory changes have mainly been reported in
patients with diarrhea-predominant IBS and postinfectious IBS and have been detected
in the small bowel [17]. Interestingly, we detected inflammatory changes across all IBS subtypes included
in our cohort (56.8 % had constipation-predominant IBS). To the best of our knowledge,
our study might be the first to use pCLE to evaluate microinflammation markers in
vivo in the colon of patients with IBS.
IBS diagnosis is currently based on the Rome IV criteria [3]
[4]
[7], and neither endoscopic nor histologic markers can improve IBS diagnostic accuracy.
Some have proposed that inflammatory cell distribution in the colon mucosa may be
useful to facilitate the diagnosis of IBS [12]; however, one study found no difference in global cellularity in colonic biopsies
of four distinct regions of the colon between 14 IBS patients and 20 control subjects
[10]. Our study has shown that IBS patients have a higher prevalence of colorectal mucosa
microinflammation detected via pCLE and histological evaluation, with an improvement
in sensitivity over the IV Rome criteria questionnaire. However, a pilot study about
the distribution of inflammatory cells in the colon was not able to detect a difference
in the global cellularity between IBS patients and control subjects [10].
In the present study, our pCLE analysis of all colonic segments (using the proposed
inflammatory criteria for the diagnosis of microinflammation in patients with IBS)
had a sensitivity of 86.7 % and a specificity of 88.7 % using histopathological analysis
of the inflammation as the gold standard.
The cost of performing a pCLE evaluation of the colon during colonoscopy is $375.00,
with an increase in procedure time of approximately 10 minutes. Moreover, the implementation
of pCLE during colonoscopy might play a role in a positive diagnostic strategy for
IBS, thus avoiding making a diagnosis of IBS solely after the exclusion of other medical
conditions. Furthermore, current protocols of random biopsies of the colon (four biopsies
every four quadrants) in patients with inflammatory bowel disease are inferior compared
to pCLE targeted biopsies for the detection of intraepithelial neoplasia [22]. In addition, pCLE has the advantage of being cost-effective compared to random
biopsies, considering that digital biopsy via pCLE is cost-effective when more than
10 biopsies are indicated in the patient [23].
Our study has the advantage of detecting microinflammation via pCLE in the colorectal
mucosa of patients with IBS, a prevalent condition worldwide. Previous studies describing
low grade inflammation used expensive, quantitative, and time-consuming methods such
as counting the number and distribution of inflammatory cells and the number of cytokines
in the colonic mucosa. However, pCLE offers a real-time evaluation of the colonic
mucosa with a reliable detection of low grade inflammation, as confirmed by the histological
results in this study. Our study is limited by the small IBS population and its single-center
nature. Although the Geboes score was developed for judging ulcerative colitis inflammation,
we used this score to assess inflammation in the colonic mucosa of patients with IBS. In
addition, an objective measurement of IBS severity using validated scales was not
carried out in our study. Even with these constraints, all possible misdiagnoses were
excluded before pCLE and histopathological analysis, and our population was adequately
representative and included different IBS subtypes.
The present study showed the potential benefit of pCLE for identifying signs of microinflammation
in each segment of the colon in patients with IBS in addition to histopathological
deviations and opens a discussion about evaluating other specific treatments, such
as budesonide and mesalazine, for IBS patients with documented low grade microinflammation
[24]. In addition, the higher prevalence of low grade inflammation in the colonic mucosa
opens a discussion about the role of low grade microinflammation in the pathogenesis
of IBS and the rationale for anti-inflammatory drugs for the management of IBS.
Further prospective multicenter studies with larger cohorts are now necessary to validate
and ensure the utility of pCLE in mapping inflammation in the colonic mucosa in patients
with IBS. Additionally, it would be interesting to evaluate pCLE inflammatory patterns
by IBS subtypes and IBS severity of symptoms and determine the stage after initial
symptom onset at which pCLE can accurately detect inflammation in IBS patients.
In conclusion, pCLE proved to be a reliable method for detecting colorectal mucosa
microinflammation in patients with IBS, showing that patients with IBS have a six-fold
higher prevalence of colorectal mucosa microinflammatory features than healthy patients.
pCLE evaluation of the colon is an accurate diagnostic test for IBS microinflammation
detection and could be considered in a positive diagnostic approach. We hope that
this study will encourage research in the field of microinflammation in the colons
of patients with IBS.
