|Year : 2019 | Volume
| Issue : 4 | Page : 563-572
Fecal B-cell-activating factor as a new noninvasive marker in the evaluation of ulcerative colitis Egyptian patients: a comparative cross-sectional study
Hany A Hussein, Rasha S Mohamed
Department of Internal Medicine, Gastroenterology and Hepatology Unit, Ain Shams University, Cairo, Egypt
|Date of Submission||28-Aug-2019|
|Date of Acceptance||08-Sep-2019|
|Date of Web Publication||18-Aug-2020|
MD Hany A Hussein
Internal Medicine, Department of Internal Medicine, Gastroenterology and Hepatology Unit, Ain Shams University, Abbasyia Square, Cairo 11211
Source of Support: None, Conflict of Interest: None
Background and aim Diagnosis of ulcerative colitis (UC) is suspected clinically and confirmed through endoscopic biopsy. It can be followed-up and assessed by noninvasive biomarkers such as fecal calprotectin. Recently, B-cell-activating factor (BAFF) has been proposed to be a regulator of B-cell and T-cell immune responses and to be associated with inflammatory processes in autoimmunity. The aim of our study was to clarify the role of fecal BAFF as a simple predictor for disease activity and severity in patients with UC.
Patients and methods Fifty Egyptian patients with UC were divided into two groups: group I including 40 patients with active UC (newly diagnosed) and group II including 10 patients with inactive UC (previously diagnosed); disease activity was assessed according to the Mayo activity scoring index; fecal BAFF and fecal calprotectin were measured for all patients using enzyme-linked immunosorbent assay.
Results Significantly higher levels of Fecal BAFF and fecal calprotectin were found among patients with active UC, as compared with inactive UC patients. Fecal BAFF more than or equal to 50 μg/g had 97.5% sensitivity and 100% specificity in predicting disease activity in comparison with fecal calprotectin, which had a sensitivity and specificity of 90% at a cut off value more than or equal to 47 μg/g. In predicting disease severity, fecal BAFF more than or equal to 340 μg/g had a sensitivity of 95% and specificity of 100%, while fecal calprotectin more than or equal to 170 μg/g had a sensitivity of 80% and specificity of 95%.
Conclusion Fecal BAFF is more sensitive and specific in predicting UC activity and severity than fecal calprotectin.
Keywords: biomarker, fecal b-cell-activating factor, fecal calprotectin, inflammatory bowel disease, ulcerative colitis
|How to cite this article:|
Hussein HA, Mohamed RS. Fecal B-cell-activating factor as a new noninvasive marker in the evaluation of ulcerative colitis Egyptian patients: a comparative cross-sectional study. Egypt J Intern Med 2019;31:563-72
|How to cite this URL:|
Hussein HA, Mohamed RS. Fecal B-cell-activating factor as a new noninvasive marker in the evaluation of ulcerative colitis Egyptian patients: a comparative cross-sectional study. Egypt J Intern Med [serial online] 2019 [cited 2020 Sep 22];31:563-72. Available from: http://www.esim.eg.net/text.asp?2019/31/4/563/292192
| Introduction|| |
Ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD) characterized by attacks of remissions and exacerbations. Although endoscopic modalities with biopsy sampling seem to be the most reliable method for estimating disease severity, they are invasive and costly .
Many serum markers are in common use in reflecting UC disease activity; however, they have only modest accuracy. Therefore, adjunctive use of other serum markers that will be more sensitive and specific for determination of disease activity and severity is strongly needed in daily clinical practice .
B-cell-activating factor (BAFF), a member of the tumor necrosis factor (TNF) superfamily predominantly produced by myeloid cells and neutrophils, is critical for the maintenance of normal B-cell development and homeostasis . Dysregulated expression and/or function of BAFF has been demonstrated to be associated with several autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, primary Sjogren’s syndrome, and B-cell malignancies .
However, limited data are present on the role of BAFF in UC; hence, the aim of our study was to investigate the role of fecal BAFF in evaluating the activity and severity of UC.
| Patients and methods|| |
Over a period of 8 months, this comparative cross-sectional study was performed on 50 Egyptian patients who were more than or equal to 18 years old and diagnosed as UC patients by colonoscopy and tissue histopathology. This study was performed according to the ethical standards for human experimentation approved by the human research committee of Ain Shams University Hospitals and informed written consents were obtained from all participants. They were recruited from the Gastroenterology outpatients’ clinic and department of Ain Shams University hospitals.
- They were divided into two groups:
Group I: 40 patients with active UC (newly diagnosed).
Group II: 10 patients with inactive UC (previously diagnosed and are being followed-up in the gastroenterology outpatients’ clinic)
- The activity of UC was assessed according to Mayo activity scoring index, which is a combined endoscopic and clinical scale; it was first proposed by Schroeder et al. . It is a composite of subscores from four categories: stool frequency, rectal bleeding, findings of colonoscopy, and physician’s global assessment ([Figure 1]). It ranges from 0 to 12, with higher scores indicating more severe disease .
- Patients with rheumatoid arthritis, systemic lupus erythematosus, primary Sjogren’s syndrome, and B-cell malignancies.
- Patients having infectious colitis within 1 month or microscopic colitis.
- Patients with a history of colorectal surgery or colorectal cancer.
- Patients who were regularly taking NSAIDs before their enrollment.
| Methods|| |
After obtaining informed written consent, the included patients were subjected to the following:
- Full history taking and clinical examination with special emphasis on abdominal pain, weight loss, rectal bleeding, diarrhea, malaise, lethargy, anorexia, nausea, tenesmus, abdominal distension, the passage of mucous, vomiting and low-grade fever. Past history of appendectomy or other operations and positive family history of IBD were also recorded, along with full clinical examination. The frequency of bowel movements and amount of rectal bleeding were scored as 0, 1, 2, 3, according to the Mayo score of activity index .
- Laboratory investigations:
- Complete blood picture.
- Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) titer.
- Rheumatoid factor titer, antinuclear antibody, anti-Ro and anti-La antibodies.
- Liver function tests: alanine transaminase, aspartate transaminase, total bilirubin, serum albumin and prothrombin time.
- Kidney function tests: serum creatinine, blood urea nitrogen, sodium (Na) and potassium (K).
- Complete stool analysis, culture and sensitivity to exclude the presence of infection (whenever needed).
- Fecal calprotectin titer:
Calprotectin assay was measured in fecal extracts by enzyme-linked immunosorbent assay using the PhiCal Calprotectin kit (Immundiagnostik AG, Bensheim, Germany) according to the manufacturer’s instructions.
- Fecal BAFF titer:
BAFF contained in fecal extracts was measured using the enzyme-linked immunosorbent assay kit (Quantikine Human BAFF/BLyS/TNFSF13B Immunoassay by R&D Systems Inc., Boston: 1 Broadway, Floor 14 Cambridge, MA, USA and Canada) according to the manufacturer’s instructions.
Reference values for stool:
Less than or equal to 50.0 μg/g was considered normal, from 50.1 to 120.0 μg/g was borderline, more than or equal to 120.1 μg/g was abnormal .
- Endoscopic assessment:
Magnesium citrate, an osmotic laxative (FDA approved), was used for bowel preparation before endoscopic workup . Colonoscopy (CF-Q260; Olympus, Tokyo, Japan) was performed, and multiple biopsies were taken by experienced endoscopists who scored the intestinal inflammation activity according to Mayo activity scoring index , blinded to the fecal markers’ results. Biopsies were examined by an expert histopathologist to confirm the diagnosis of UC.
The collected data were revised, coded, tabulated and introduced to a PC using Statistical package for Social Science (SPSS 19.0.1 for Windows, 2001; SPSS Inc., Chicago, Illinois). Statistical presentation and analysis of the present study was conducted, using the mean±SD, χ2, linear correlation coefficient (r), analysis of variance test and receiver operating characteristic curve analysis. P value less than 0.05 was considered statistically significant.
| Results|| |
Our study included 50 Egyptian patients diagnosed as having UC; there were 24 (48%) male individuals and 26 (52%) female individuals, aged 17–47 years old (mean age, 33.8±7.8 years), as shown in [Table 1] with their laboratory data.
According to the Mayo score of activity index, they were classified into the following groups: group I: 40 patients with active UC (their score range, 3–12) and group II: 10 patients with inactive UC (their score ≤2 and no subscore > 2). Active UC patients (n=40) were further classified according to their scores into those having mild disease (50%) (n=20), moderate disease (32.5%) (n=13), and severe disease (17.5%) (n=7), as shown in [Figure 2].
|Figure 2 Distribution of active UC patients according to disease severity. UC, ulcerative colitis.|
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Comparison between active (group I) and inactive UC (group II) patients with regard to their demographic data revealed no statistical significance as regards their age, sex, and family history of IBD.
While comparing the laboratory data between group I and group II, there was significant difference between them concerning hemoglobin concentration, as it was lower in active UC patients than in the inactive group (with a mean of 11.7 and 14.2, respectively) (P>0.05). As regards ESR and CRP, there were statistically significant differences between the two groups, as both titers were higher in patients with active UC (P<0.05). Concerning fecal calprotectin titer, there was significant difference between both groups, as titer was higher in patients with active UC (P<0.05). As regards fecal BAFF titer, there was a statistically significant difference between the two groups, as shown in [Table 2].
|Table 2 Comparison between the two groups as regards laboratory investigations|
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On comparing different disease severity groups of active UC (n=40) as regards fecal markers (fecal calprotectin titer and fecal BAFF titer), there was a significant difference between the three groups with highest mean titer in patients with severe UC (778.57±244.71 and 1248.57±330.93, respectively, with P<0.05), as shown in [Table 3] and [Table 4]. Moreover, there was a positive significant correlation between fecal markers and disease severity, as fecal calprotectin titer and fecal BAFF titer increase with severity of UC (r=0.75 and r=0.897, respectively, with P<0.05) ([Figure 3] and [Figure 4]). Correlation between fecal markers and studied parameters in all patients (n=50) revealed positive significant correlation between them and ESR, CRP and Mayo activity score, with negative significant correlation with hemoglobin (P<0.05), as shown in [Table 5] and [Table 6].
|Table 3 Comparison between fecal calprotectin titer and disease severity in active ulcerative colitis patients (group I) (N=40)|
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|Table 4 Comparison between fecal B-cell-activating factor titer and disease severity in group I patients (N=40)|
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|Figure 3 Correlation between fecal calprotectin titer and disease severity.|
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|Figure 4 Correlation between fecal BAFF titer and disease severity. BAFF, B-cell-activating factor.|
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|Table 5 Correlation between fecal calprotectin titer and studied parameters in all patients (n=50)|
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|Table 6 Correlation between B-cell-activating factor and other parameters in all patients (N=50)|
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At the best cut-off value of more than or equal to 50 μg/g, fecal calprotectin had a sensitivity of 90% and a specificity of 90%, for detection of active UC patients over inactive ones using receiver operating characteristic curve analysis with an overall accuracy of 95.5% ([Table 7], [Figure 5]), whereas fecal BAFF can predict active UC patients from inactive ones at the cutoff point of more than or equal to 47 μg/g with a sensitivity of 97.5% and specificity of 100%, with an overall accuracy of 99.8% ([Table 7], [Figure 5]).
|Table 7 Comparison between fecal B-cell-activating factor and fecal calprotectin titers as regards sensitivity and specificity to disease activity|
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|Figure 5 ROC curve representing sensitivity and specificity of fecal BAFF and fecal calprotectin in disease activity. BAFF, B-cell-activating factor; ROC, receiver operating characteristic.|
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With further subdivision of the first group according to the severity of the disease, the following was revealed: fecal calprotectin at a cut-off value more than or equal to 170 μg/g had 80% sensitivity and 95% specificity in predicting severe UC among active UC cases, with an overall accuracy of 88% ([Table 8], [Figure 6]). In contrast, and at a cut off value more than or equal to 340 μg/g, fecal BAFF had 95% sensitivity and 100% specificity in predicting severe UC among active UC cases, with an overall accuracy of 98.7% ([Table 8], [Figure 6]).
|Table 8 Comparison between fecal B-cell-activating factor and fecal calprotectin titers as regards sensitivity and specificity to disease severity|
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|Figure 6 ROC curve representing sensitivity and specificity of fecal BAFF and fecal calprotectin in disease severity. BAFF, B-cell-activating factor; ROC, receiver operating characteristic.|
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| Discussion|| |
Diagnosis of UC is based on a combination of history and examination, blood parameters, endoscopy and tissue histopathology . In order to avoid invasive investigations, several noninvasive markers have been evaluated for their capacity to distinguish between functional and organic inflammatory gastrointestinal disease . However, they still have limited capacity for prediction of disease activity and severity . It is evident that a simple, rapid, sensitive, specific, noninvasive marker to evaluate colonic inflammation in UC is needed .
Therefore the focus of this study was to evaluate the utility of fecal BAFF as a simple, easy and available predictor for disease activity and severity in patients with UC.
According to the Mayo activity scoring index , the studied patients were divided into two groups: 10 patients with inactive UC and 40 patients with active UC, subdivided into 20 patients with mild disease, 13 moderate and seven patients with severe UC.
As regards demographic data, the mean age of cases of UC was 33.8±7.8 years. This was in accordance with another study conducted by Zahedi et al. , who reported that the mean age of patients with UC was 39.4 years.
Under normal circumstances, CRP is produced by hepatocytes in low quantities (<1 mg/l). However, following an acute-phase stimulus such as inflammation, hepatocytes rapidly increase the production of CRP under the influence of interleukin‐6 and TNF‐α and may reach peak levels of 350–400 mg/l . The ESR determination reflects the changes in the various acute-phase proteins . Hence, as part of acute-phase reactants, both ESR and CRP are increased in active UC patients compared with inactive patients.
In our study, CRP was significantly elevated in patients with active UC compared with those with inactive UC, with mean values of 27.4±23.2 and 4.6±4, respectively. ESR also was higher in group I patients than in group II patients, with mean values of 36.6±27.3 and 11.1±6.4, respectively. Our study was in line with Peyrin-Biroulet et al. , and Solem et al. , who found that ESR and CRP were helpful in differentiating active IBD from inactive IBD; hence, they might be used as markers of disease activity. However, ESR may be influenced by the size, shape, and number of erythrocytes and by other factors, including age, sex, anemia, blood dyscrasias, and pregnancy, which can account for the different results between the studies .
It is known that colonoscopy and taking biopsies for histopathological examination is essential for diagnosing IBD. It is used to make an initial diagnosis of IBD, distinguish CD from UC, assess disease extension and activity, and monitor response to treatment and survey for dysplasia .
Aiming to find noninvasive markers for diagnosis of IBD, fecal biomarkers are the most important markers, which comprise a group of substances that are produced by the inflamed neutrophils in intestinal mucosa. The main use of these markers is in diagnosing and assessing disease severity. They may also have a role in assessing treatment effect and prediction of relapse .
As regards fecal calprotectin titer, we found in our study that there was a significant difference between both groups, being higher in the active group with a mean value of 264.4±279.56 μg/g and a mean value of 34.5±22.79 μg/g in the inactive group (P=0.013). Concerning disease severity, there was also a statistically significant difference between different disease severity groups of active UC (P>0.001). Using Spearman’s rho, there was a positive significant correlation between fecal calprotectin titer and disease severity, as its titer increases with severity of UC (r=0.75, P<0.001). This was in agreement with a study conducted by Silberer et al. , who found that fecal calprotectin correlates with the endoscopically assessed severity of intestinal inflammation. Moreover, Egea-Valenzuela et al. , have proposed fecal calprotectin as a biomarker of enteric inflammation, as its presence in the stool is directly proportional to neutrophil activity in the intestinal lumen. Our study was also in line with the study by Paduchova and Durackova , who proposed the role of fecal calprotectin to differentiate mild from moderate inflammation of the gastrointestinal tract.
Concerning fecal BAFF titer, our study found that there was a statistically significant difference between both groups, it being higher in the active group (P=0.001) with a mean value of 497.68±406.14 μg/g and a mean value of 26±10.5 μg/g in the inactive group. Comparing the ratios as regards disease severity according to Mayo activity scoring index, there was a statistical significance of fecal BAFF titer for determining disease severity as mild, moderate and severe, with the mean for them being 225.6, 511.9 and 1248.6 μg/g, respectively, with P value less than 0.001. Using Spearman’s rho, there was positive significant correlation between fecal BAFF titer and disease severity, as its titer increases with severity of UC (r=0.897, P<0.001). This study was in line with the study carried out by Zhang et al. , which demonstrated that BAFF expression is increased in serum, local colon, and feces of patients with IBD. Furthermore, a strong positive correlation was observed between BAFF and disease activity in patients with UC, and also with proinflammatory cytokines TNF-α and interleukin-1b. These results highlight an important role of elevated BAFF levels in the pathogenesis of IBD.
Comparing the two groups as regards disease activity, fecal calprotectin’s sensitivity and specificity were 90% at a cut-off value of more than or equal to 47 μg/g with an accuracy of 95.5%, positive predictive value (PPV) of 97.3% and negative predictive value (NPV) of 69.2%; while fecal BAFF’s sensitivity and specificity were 97.5 and 100%, respectively, at a cut-off value of more than or equal to 50 μg/g with an accuracy of 99.8%, PPV of 100% and NPV of 90.9%, which implies that fecal BAFF is more sensitive and specific than calprotectin for determining disease activity (according to Mayo activity scoring index). Furthermore, as regards the disease severity, fecal calprotectin’s sensitivity and specificity were 80 and 95%, respectively, at a cut-off value of more than or equal to 170 μg/g, with an accuracy of 88%, 94.1% PPV, and 82.6% NPV, while fecal BAFF’s sensitivity and specificity were 95 and 100% at a cut-off value of more than or equal to 340 μg/g, with an accuracy of 98.7%, 100% PPV, and 95.2% NPV; hence, fecal BAFF was also more sensitive and specific for determining disease severity than calprotectin.
This was in agreement with Fu et al. , who detected fecal BAFF and calprotectin levels in the same samples; they implied that fecal BAFF could be a good indicator for overall evaluation of mucosal inflammation and severity. As regards disease severity, BAFF more than or equal to 227.3 μg/g yielded 84% sensitivity, 100% specificity, 100% PPV, and 64% NPV, while calprotectin more than or equal to 50 μg/g yielded 76% sensitivity, 93% specificity, 97% PPV, and 53% NPV. Hence, fecal BAFF has a better performance as compared with fecal calprotectin in the evaluation of intestinal inflammation in UC.
The present study had a few limitations. First, the number of patients included in the present study is relatively small. Second, the underlying relations between fecal BAFF, calprotectin and extension of UC were not studied.
| Conclusion|| |
Our results revealed that fecal BAFF is a simple and noninvasive marker that can be helpful for differentiating active UC from inactive disease; it also correlates with grade of severity and with higher sensitivity and specificity than fecal calprotectin in determining disease activity and severity, implying that BAFF is a promising biomarker in UC and that it can be an additive to the other tools that clinicians use in practice. Future studies may be needed to evaluate the role of fecal BAAF as a biomarker for surveillance of colonic cancer in UC patients.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8]