- Email: [email protected]
Fecal Calprotectin and serum chromogranin A as potential biomarkers of irritable bowel syndrome symptom severity
Medical Hypotheses xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
Medical Hypotheses journal homepage: www.elsevier.com/locate/mehy
Fecal Calprotectin and serum chromogranin A as potential biomarkers of irritable bowel syndrome symptom severity q Sanda Pletikosic a, Ivana Plavsic b, Goran Hauser b,c,⇑, Mladenka Tkalcic a a
Department of Psychology, Faculty of Humanities and Social Sciences, University of Rijeka, Croatia Centre for Emergency Medicine, Clinical Hospital Centre, Rijeka, Croatia c Department of Internal Medicine, Division of Gastroenterology, Clinical Hospital Centre, Rijeka, Croatia b
a r t i c l e
i n f o
Article history: Received 19 July 2014 Accepted 13 June 2015 Available online xxxx
a b s t r a c t Irritable bowel syndrome (IBS) is a disorder of the lower gastrointestinal (GI) tract, which manifests as abdominal pain and/or discomfort accompanied by altered bowel function, in the absence of structural pathology. The onset and precipitation of IBS is the result of an interaction among several factors, including psychological distress, altered GI sensation and processing of sensory information as well as GI inflammation. These factors have varying contributions to disorder etiology in different patients, and in line with that, there is now emerging evidence about a low-grade inflammation in a subgroup of IBS patients. Because IBS diagnosis is based on the ROME III criteria, with the exclusion of structural pathology, patients are often exposed to numerous invasive and unpleasant tests. In order to decrease the cost of repeated testing, while simultaneously alleviating patients’ anxiety, research should be aimed at detecting cost-effective biomarkers. We hypothesize chromogranin A (CgA) and fecal Calprotectin (FC) could be used to eliminate possible organic causes of IBS symptoms. Also, we hypothesize FC could be helpful in detecting IBS patients with low-grade inflammation. Forty-eight outpatients with IBS (76% females) completed a set of psychosocial measures (HRQoL, STAI, BDI, VSI, SF-36), and their FC and CgA levels were obtained. We found elevated CgA levels in 4 patients, but CgA levels were not related to any of the psychological measures used. Elevated FC levels were found in 12 patients. FC levels significantly correlated with the physical component of health related quality of life (HRQoL) (r48 = .42, p < .01). In addition, one-way ANOVA’s were performed to test possible differences in psychosocial measures depending on the patient’s FC status. The analysis showed only one significant difference. Patients with the highest levels of FC had significantly lower physical component of HRQoL compared to the other two groups of patients. Ó 2015 Elsevier Ltd. All rights reserved.
Introduction/background Irritable bowel syndrome (IBS) is a disorder of the lower gastrointestinal (GI) tract, which manifests as abdominal pain and/or discomfort accompanied by altered bowel function, in the absence of biochemical or structural pathology [1,2]. Irritable bowel syndrome has a substantial negative impact on patients’ quality of life and may affect between 1% to more than 20% of adults. IBS is one of the most common conditions managed by primary care physicians and gastroenterologists worldwide [1,3]. Diagnosis is based on q This study was funded in part by the Ministry of Science, Education and Sport, Republic of Croatia, Grant Number 009-0092660-2655 and University of Rijeka, Grant Number 13.04.1.3.1. ⇑ Corresponding author at: Department of Internal Medicine, Division of Gastroenterology, Clinical Hospital Centre, Rijeka, Kresimirova 42, 51000 Rijeka, Croatia. Tel.: +385 51 568 122; fax: +385 51 658 386. E-mail address: [email protected] (G. Hauser).
clinical appearance and Rome III criteria for functional gastrointestinal disorders (FGID) with the exclusion of red flag symptoms [1,2]. Patients with IBS are divided into subgroups based on their predominating symptoms to diarrhea predominant (IBS-D), constipation predominant (IBS-C), mixed type with diarrhea and constipation (IBS-M) and un-determined IBS. Around 75% of the patients are alternators, which illustrate the instability of symptoms over time, another characteristic of IBS [1,2]. The pathophysiology of IBS remains largely unclear due to its complex multidimensional nature. The onset and precipitation of the disorder is the result of an interaction among several factors, which can include psychological distress, affective disturbances, abnormalities of GI sensation, altered processing of afferent sensory information, motility disturbances, and GI inflammation and infection [3–6]. It is reasonable to assume that these factors have varying contributions to disorder etiology in different patients. In line with that assumption, there is now emerging evidence about
http://dx.doi.org/10.1016/j.mehy.2015.06.008 0306-9877/Ó 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Pletikosic S et al. Fecal Calprotectin and serum chromogranin A as potential biomarkers of irritable bowel syndrome symptom severity. Med Hypotheses (2015), http://dx.doi.org/10.1016/j.mehy.2015.06.008
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S. Pletikosic et al. / Medical Hypotheses xxx (2015) xxx–xxx
a low-grade mucosal inflammation that exists in a subgroup of IBS patients [7–10]. Regardless of etiology, IBS patients have heightened anxiety and depression scores, compared to healthy controls [11–14], as well as a significantly lower quality of life [11,15,16]. Lack of reliable diagnostic tests for IBS, combined with the patients’ anxiety and stress induced by symptom variability, could lead to increased health care seeking [17,18], consequently exposing patients to numerous invasive, unpleasant and often unnecessary tests. Consequently, IBS becomes not only debilitating for the patient, but also a great social and economic burden [2]. In order to decrease the cost of repeated diagnostic tests, while simultaneously alleviating patients’ anxiety and worry, research should be aimed at detecting cost-effective biomarkers [7]. Connor et al. describe the ideal biomarker as one that exhibits accuracy, reproducibility, sensitivity, specificity and patient acceptability [19]. Patient acceptability is usually greatest for noninvasive procedures, such as serological and fecal tests, so it is reasonable to explore the possible value and diagnostic contribution of serum and fecal biomarkers. One of the most promising fecal biomarkers is Calprotectin, a neutrophil derived protein which has been useful as a marker for inflammatory bowel disease (IBD) [20,21]. Fecal Calprotectin (FC) accounts for about 60% of the soluble proteins in the cytosol fraction of neutrophil granulocytes. It’s released by granulocyte activation, resulting in increased levels in stool samples of patients with active inflammation within the intestinal mucosa. Inflammation causes neutrophil activation, which results in FC release proportionate to the degree of inflammation [22]. There is growing evidence FC can be used as a non-invasive marker for intestinal/colonic inflammation [23], which could be useful in pre-screening, to decrease the number of unnecessary colonoscopies. FC reliably distinguishes IBD from functional GI disorders [21,24,25] and correlates well with IBD disease activity [24]. Increased levels have also been found in microscopic colitis [26]. Compared to fecal biomarkers, serum biomarkers are nonspecific and less successful at indicating localized inflammation in the intestinal mucosa [27]. However, some serum biomarkers are more informative than others, especially for eliminating possible biological causes underlining IBS symptoms. One such possible biomarker is chromogranin A (CgA). Chromogranins are the major components of most neuroendocrine cells. These proteins are ubiquitous in vesicles of secretory cells of the enteric, endocrine and immune systems and may reflect the activity of these systems. They are clinically relevant as markers for neuroendocrine tumors, but recent studies also indicate there could be altered (higher) plasma levels of CgA in patients with inflammatory bowel diseases [28] and IBS patients [29]. The hypothesis Considering IBS is diagnosed by excluding possible organic causes of the symptoms, there is a need for non-invasive diagnostic procedures. We hypothesize that serum CgA and FC could be used for this purpose. Elevated levels of CgA can indicate the presence of neuroendocrine tumors, while elevated FC levels are a clear indicator of bowel inflammation. Furthermore, FC could differentiate among IBS patients with and without low-grade inflammation. The presence of a low-grade inflammation could be related to symptom exacerbation and present an additional burden on patient’s quality of life. Evaluation of hypothesis Research consistently shows IBS patients express negative or clinically insignificant levels of FC. Compared to IBD patients, IBS patients have significantly lower levels of Calprotectin [30–32]
while no differences in FC are found when comparing them to healthy persons [30,32,33]. This would imply that FC can successfully distinguish IBD from IBS and prevent unnecessary colonoscopies in IBS patients. However, with a cut-off of 50 lg/g the specificity of FC is only moderate (74%), possibly indicating an organic condition such as low-grade inflammation in a portion of the IBS patients [34]. FC could also be useful for determining symptom severity or disease activity. In a study investigating the differences between IBD patients in remission with and without IBS-like symptoms, FC was significantly higher in those with IBS-like symptoms [35]. This could reflect a connection between IBS-like symptoms and microscopic inflammation in the absence of structural disease [36]. In another study, FC was related to endoscopic disease activity, with an accuracy of 89% in discriminating between an inactive, mild, moderate or highly active disease [37]. FC could serve as a screening for inflammation, prior to colonoscopy, as well as supplement information relevant for treatment. Research on CgA in IBS patients has provided somewhat conflicting results. Serum CgA levels were found to be normal in the majority of a sample of IBS-D patients, while around 7% of them (N = 15) showed elevated levels of serum CgA (>60 u/L). In 8 of those patients CgA levels normalized at follow-up, while tumors were detected in 2 of the patients [38]. In another study comparing patients with different IBS subtypes, no differences in serum CgA were found between IBS-D, IBS-C and healthy controls [39]. Finally, a sample of patients with self-reported food hypersensitivity, 89% of whom met ROME II criteria for IBS, had lower serum CgA levels than healthy controls [40]. It would seem that CgA could be helpful in excluding tumors as a possible cause of the symptoms IBS patients present with. Health related quality of life (HRQoL) is an important outcome measure in IBS, and research shows it is related to both the severity of physical symptoms as well as psychological symptom severity. Thus, quality of life can be regarded as two separate constructs, physical and mental HRQoL. Physical HRQoL refers to physical limitations in everyday functioning which are a result of bodily pain or low general health, while mental HRQoL reflects functional limitations resulting from negative mood, or poor mental and social functioning [41]. Compared to healthy controls, IBS patients have significantly lower quality of life scores [42], as do IBD patients [43]. When comparing the two patient groups, they show similarly reduced quality of life [43]. If the physical and mental components of HRQoL are taken into account, IBD patients show lower physical HRQoL scores, but there are no differences between these groups in mental HRQoL [44]. The difference in physical HRQoL is most likely the result of a difference in symptom severity, which is underlined by inflammation and structural changes in IBD patients. Considering that IBD patients in remission with IBS-like symptoms who have higher FC levels also have lower HRQoL than patients without IBS-like symptoms [35], it is possible that low-grade inflammation can lead to symptom exacerbation and a consequential reduction in HRQoL in IBS patients as well.
Empirical data Forty-eight outpatients with irritable bowel syndrome (age M = 45.20, SD = 14.15; 76% females) completed a set of psychosocial measures including State-Trait Anxiety Inventory (STAI-T), Visceral Sensitivity Index (VSI), Beck Depression Inventory (BDI), IBS quality of life Inventory (IBS-36) and Short Form-36 Health Survey (SF-36). In addition, the patients filled out a symptom severity diary for 14 days. The symptom severity score was calculated as the average intensity of present symptoms over the period of measurement. The patients’ FC and serum CgA levels were also obtained.
Please cite this article in press as: Pletikosic S et al. Fecal Calprotectin and serum chromogranin A as potential biomarkers of irritable bowel syndrome symptom severity. Med Hypotheses (2015), http://dx.doi.org/10.1016/j.mehy.2015.06.008
S. Pletikosic et al. / Medical Hypotheses xxx (2015) xxx–xxx
It is important to note that no CgA was found in almost 46% of the sample, while data was not available for 29% of the sample. In the rest of the sample (N = 12) CgA levels ranged from 6 to 163 u/L. We found elevated CgA levels (>60 u/L) [39] in 4 patients. Although 40% of the sample tested negatively for FC, the rest of the sample presented with varying FC levels, ranging from 31 lg/g to 300 lg/g. Twelve patients had FC levels above 50 lg/g, of whom only 3 patients had FC levels above 100 lg/g. In order to determine the relationship between biological markers and IBS severity correlational analyses were performed. As we expected, CgA did not correlate with FC, because it predominantly serves as neuroendocrine tumor marker while FC is used as an inflammation marker. However, CgA showed no significant correlation with any other measure used, thus no other analyses were performed. On the other hand, the level of FC significantly correlated with the physical component of HRQoL (r48 = .42, p < .01). In addition, one-way ANOVA’s were performed to test possible differences in psychosocial measures depending on the patient’s FC status (less than 30 lg/g, from 31 to 50 lg/g, more than 51 lg/g). The analysis showed only one significant difference. Patients with the highest levels of FC had significantly lower physical component of HRQoL (PC HRQoL) compared to the other two groups of patients, which can be seen in Fig. 1. Consequences of the hypothesis This preliminary data shows that serum CgA was not detected at all, or it was present in insignificant levels, in the majority of the sample (91%), thus it can be useful in eliminating endocrine tumors as the cause of reported symptoms. CgA did not offer any additional relevant information for IBS symptom severity. This is in line with previous findings. Although some researchers found reduced CgA cell density in IBS patients compared to healthy controls, there were no differences in CgA plasma levels [39]. It would seem that because CgA levels reflect the total endocrine activity of the body, they are not specific or sensitive enough to have any clinical value for the evaluation of symptom severity or disease progress in IBS. Contrary to CgA, FC levels seem to be clinically relevant for evaluating IBS patients. Again, most IBS patients (75%) had undetectable or clinically insignificant levels of FC, indicating that low-grade inflammation is not a significant contributor to their disease etiology. Additionally, patients with values above the clinical cut-off (50 lg/g) [34] had a significantly lower physical quality of life. This indicates that FC not only serves as a good marker of low-grade inflammation, but helps identify patients with more severe physical limitations due to bodily pain and low physical
Fig. 1. Differences in PC HRQoL depending on FC status.
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and general health. It is interesting to note that patients above and below the cut-off for FC did not differ in the mental component of HRQoL or any other psychological measure. These findings support the clinical importance of FC in IBS. In conclusion, CgA could be included in the IBS diagnostic procedure in order to exclude the existence of endocrine tumors. On the other hand, FC should be included to detect the existence of inflammation. The inclusion of FC in IBS diagnosis has several other advantages. First, bearing in mind that a pro-inflammatory state can aggravate symptoms of IBS and decrease patients’ HRQoL it is of great importance to detect inflammation as a possible cause of IBS symptoms. Second, blood and stool tests are much more acceptable for patients compared to invasive procedures. Third, the effectiveness of therapy and disease severity could be easily tracked through time. Finally, differentiating between patients with predominant psychological disturbances from patients with predominantly inflammatory causes would lead to more adequate and timely treatment for both groups of patients. This is especially important for patients with low-grade inflammation who could benefit from anti-inflammatory medication not only in symptom reduction but also indirectly in the improvement of their quality of life. Of course, this does not imply we should abandon symptom-based criteria for IBS but only that such additional measures of potential low-grade inflammation could be useful for determining the underlying mechanisms of symptom generation and perpetuation [45]. Conflict of interest Authors declare no conflict of interest. References [1] Brandt LJ, Chey WD, Foxx-Orenstein AE, et al. An evidence-based position statement on the management of irritable bowel syndrome. Am J Gastroenterol 2009;104(Suppl. 1):S1–S35. [2] El-Salhy M, Mazzawi T, Gundersen D, Hausken T. Chromogranin A cell density in the rectum of patients with irritable bowel syndrome. Mol Med Rep 2012;6:1223–5. [3] Fichna JMAS. Brain–gut interactions in IBS. Front Pharmacol 2012;3:127. [4] Porcelli P, Todarello O. Psychological factors affecting functional gastrointestinal disorders. Adv Psychosom Med 2007;28:34–56. [5] Spiller R, Aziz Q, Creed F, et al. Guidelines on the irritable bowel syndrome: mechanisms and practical management. Gut 2007;56:1770–98. [6] van der Veek PP, Dusseldorp E, van Rood YR, Masclee AA. Testing a biobehavioral model of irritable bowel syndrome. Eur J Gastroenterol Hepatol 2010;22:412–9. [7] Clarke G, Quigley EM, Cryan JF, Dinan TG. Irritable bowel syndrome: towards biomarker identification. Trends Mol Med 2009;15:478–89. [8] Cremon C, Gargano L, Morselli-Labate AM, et al. Mucosal immune activation in irritable bowel syndrome: gender-dependence and association with digestive symptoms. Am J Gastroenterol 2009;104:392–400. [9] Guilarte M, Santos J, de Torres I, et al. Diarrhoea-predominant IBS patients show mast cell activation and hyperplasia in the jejunum. Gut 2007;56:203–9. [10] Ortiz-Lucas M, Saz-Peiro P, Sebastian-Domingo JJ. Irritable bowel syndrome immune hypothesis. Part one: the role of lymphocytes and mast cells. Rev Esp Enferm Dig 2010;102:637–47. [11] Cho HS, Park JM, Lim CH, et al. Anxiety, depression and quality of life in patients with irritable bowel syndrome. Gut Liver 2011;5:29–36. [12] Kovacs Z, Kovacs F. Depressive and anxiety symptoms, dysfunctional attitudes and social aspects in irritable bowel syndrome and inflammatory bowel disease. Int J Psychiatry Med 2007;37:245–55. [13] Sugaya N, Nomura S. Relationship between cognitive appraisals of symptoms and negative mood for subtypes of irritable bowel syndrome. Biopsychosoc Med 2008;2:9. [14] Tosic-Golubovic S, Miljkovic S, Nagorni A, Lazarevic D, Nikolic G. Irritable bowel syndrome, anxiety, depression and personality characteristics. Psychiatr Danub 2010;22:418–24. [15] DiBonaventura M, Sun SX, Bolge SC, Wagner JS, Mody R. Health-related quality of life, work productivity and health care resource use associated with constipation predominant irritable bowel syndrome. Curr Med Res Opin 2011;27:2213–22. [16] Huang WW, Zhou FS, Bushnell DM, Diakite C, Yang XH. Cultural adaptation and application of the IBS-QOL in China: a disease-specific quality-of-life questionnaire. Qual Life Res 2007;16:991–6.
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Please cite this article in press as: Pletikosic S et al. Fecal Calprotectin and serum chromogranin A as potential biomarkers of irritable bowel syndrome symptom severity. Med Hypotheses (2015), http://dx.doi.org/10.1016/j.mehy.2015.06.008
Contents lists available at ScienceDirect
Medical Hypotheses journal homepage: www.elsevier.com/locate/mehy
Fecal Calprotectin and serum chromogranin A as potential biomarkers of irritable bowel syndrome symptom severity q Sanda Pletikosic a, Ivana Plavsic b, Goran Hauser b,c,⇑, Mladenka Tkalcic a a
Department of Psychology, Faculty of Humanities and Social Sciences, University of Rijeka, Croatia Centre for Emergency Medicine, Clinical Hospital Centre, Rijeka, Croatia c Department of Internal Medicine, Division of Gastroenterology, Clinical Hospital Centre, Rijeka, Croatia b
a r t i c l e
i n f o
Article history: Received 19 July 2014 Accepted 13 June 2015 Available online xxxx
a b s t r a c t Irritable bowel syndrome (IBS) is a disorder of the lower gastrointestinal (GI) tract, which manifests as abdominal pain and/or discomfort accompanied by altered bowel function, in the absence of structural pathology. The onset and precipitation of IBS is the result of an interaction among several factors, including psychological distress, altered GI sensation and processing of sensory information as well as GI inflammation. These factors have varying contributions to disorder etiology in different patients, and in line with that, there is now emerging evidence about a low-grade inflammation in a subgroup of IBS patients. Because IBS diagnosis is based on the ROME III criteria, with the exclusion of structural pathology, patients are often exposed to numerous invasive and unpleasant tests. In order to decrease the cost of repeated testing, while simultaneously alleviating patients’ anxiety, research should be aimed at detecting cost-effective biomarkers. We hypothesize chromogranin A (CgA) and fecal Calprotectin (FC) could be used to eliminate possible organic causes of IBS symptoms. Also, we hypothesize FC could be helpful in detecting IBS patients with low-grade inflammation. Forty-eight outpatients with IBS (76% females) completed a set of psychosocial measures (HRQoL, STAI, BDI, VSI, SF-36), and their FC and CgA levels were obtained. We found elevated CgA levels in 4 patients, but CgA levels were not related to any of the psychological measures used. Elevated FC levels were found in 12 patients. FC levels significantly correlated with the physical component of health related quality of life (HRQoL) (r48 = .42, p < .01). In addition, one-way ANOVA’s were performed to test possible differences in psychosocial measures depending on the patient’s FC status. The analysis showed only one significant difference. Patients with the highest levels of FC had significantly lower physical component of HRQoL compared to the other two groups of patients. Ó 2015 Elsevier Ltd. All rights reserved.
Introduction/background Irritable bowel syndrome (IBS) is a disorder of the lower gastrointestinal (GI) tract, which manifests as abdominal pain and/or discomfort accompanied by altered bowel function, in the absence of biochemical or structural pathology [1,2]. Irritable bowel syndrome has a substantial negative impact on patients’ quality of life and may affect between 1% to more than 20% of adults. IBS is one of the most common conditions managed by primary care physicians and gastroenterologists worldwide [1,3]. Diagnosis is based on q This study was funded in part by the Ministry of Science, Education and Sport, Republic of Croatia, Grant Number 009-0092660-2655 and University of Rijeka, Grant Number 13.04.1.3.1. ⇑ Corresponding author at: Department of Internal Medicine, Division of Gastroenterology, Clinical Hospital Centre, Rijeka, Kresimirova 42, 51000 Rijeka, Croatia. Tel.: +385 51 568 122; fax: +385 51 658 386. E-mail address: [email protected] (G. Hauser).
clinical appearance and Rome III criteria for functional gastrointestinal disorders (FGID) with the exclusion of red flag symptoms [1,2]. Patients with IBS are divided into subgroups based on their predominating symptoms to diarrhea predominant (IBS-D), constipation predominant (IBS-C), mixed type with diarrhea and constipation (IBS-M) and un-determined IBS. Around 75% of the patients are alternators, which illustrate the instability of symptoms over time, another characteristic of IBS [1,2]. The pathophysiology of IBS remains largely unclear due to its complex multidimensional nature. The onset and precipitation of the disorder is the result of an interaction among several factors, which can include psychological distress, affective disturbances, abnormalities of GI sensation, altered processing of afferent sensory information, motility disturbances, and GI inflammation and infection [3–6]. It is reasonable to assume that these factors have varying contributions to disorder etiology in different patients. In line with that assumption, there is now emerging evidence about
http://dx.doi.org/10.1016/j.mehy.2015.06.008 0306-9877/Ó 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Pletikosic S et al. Fecal Calprotectin and serum chromogranin A as potential biomarkers of irritable bowel syndrome symptom severity. Med Hypotheses (2015), http://dx.doi.org/10.1016/j.mehy.2015.06.008
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a low-grade mucosal inflammation that exists in a subgroup of IBS patients [7–10]. Regardless of etiology, IBS patients have heightened anxiety and depression scores, compared to healthy controls [11–14], as well as a significantly lower quality of life [11,15,16]. Lack of reliable diagnostic tests for IBS, combined with the patients’ anxiety and stress induced by symptom variability, could lead to increased health care seeking [17,18], consequently exposing patients to numerous invasive, unpleasant and often unnecessary tests. Consequently, IBS becomes not only debilitating for the patient, but also a great social and economic burden [2]. In order to decrease the cost of repeated diagnostic tests, while simultaneously alleviating patients’ anxiety and worry, research should be aimed at detecting cost-effective biomarkers [7]. Connor et al. describe the ideal biomarker as one that exhibits accuracy, reproducibility, sensitivity, specificity and patient acceptability [19]. Patient acceptability is usually greatest for noninvasive procedures, such as serological and fecal tests, so it is reasonable to explore the possible value and diagnostic contribution of serum and fecal biomarkers. One of the most promising fecal biomarkers is Calprotectin, a neutrophil derived protein which has been useful as a marker for inflammatory bowel disease (IBD) [20,21]. Fecal Calprotectin (FC) accounts for about 60% of the soluble proteins in the cytosol fraction of neutrophil granulocytes. It’s released by granulocyte activation, resulting in increased levels in stool samples of patients with active inflammation within the intestinal mucosa. Inflammation causes neutrophil activation, which results in FC release proportionate to the degree of inflammation [22]. There is growing evidence FC can be used as a non-invasive marker for intestinal/colonic inflammation [23], which could be useful in pre-screening, to decrease the number of unnecessary colonoscopies. FC reliably distinguishes IBD from functional GI disorders [21,24,25] and correlates well with IBD disease activity [24]. Increased levels have also been found in microscopic colitis [26]. Compared to fecal biomarkers, serum biomarkers are nonspecific and less successful at indicating localized inflammation in the intestinal mucosa [27]. However, some serum biomarkers are more informative than others, especially for eliminating possible biological causes underlining IBS symptoms. One such possible biomarker is chromogranin A (CgA). Chromogranins are the major components of most neuroendocrine cells. These proteins are ubiquitous in vesicles of secretory cells of the enteric, endocrine and immune systems and may reflect the activity of these systems. They are clinically relevant as markers for neuroendocrine tumors, but recent studies also indicate there could be altered (higher) plasma levels of CgA in patients with inflammatory bowel diseases [28] and IBS patients [29]. The hypothesis Considering IBS is diagnosed by excluding possible organic causes of the symptoms, there is a need for non-invasive diagnostic procedures. We hypothesize that serum CgA and FC could be used for this purpose. Elevated levels of CgA can indicate the presence of neuroendocrine tumors, while elevated FC levels are a clear indicator of bowel inflammation. Furthermore, FC could differentiate among IBS patients with and without low-grade inflammation. The presence of a low-grade inflammation could be related to symptom exacerbation and present an additional burden on patient’s quality of life. Evaluation of hypothesis Research consistently shows IBS patients express negative or clinically insignificant levels of FC. Compared to IBD patients, IBS patients have significantly lower levels of Calprotectin [30–32]
while no differences in FC are found when comparing them to healthy persons [30,32,33]. This would imply that FC can successfully distinguish IBD from IBS and prevent unnecessary colonoscopies in IBS patients. However, with a cut-off of 50 lg/g the specificity of FC is only moderate (74%), possibly indicating an organic condition such as low-grade inflammation in a portion of the IBS patients [34]. FC could also be useful for determining symptom severity or disease activity. In a study investigating the differences between IBD patients in remission with and without IBS-like symptoms, FC was significantly higher in those with IBS-like symptoms [35]. This could reflect a connection between IBS-like symptoms and microscopic inflammation in the absence of structural disease [36]. In another study, FC was related to endoscopic disease activity, with an accuracy of 89% in discriminating between an inactive, mild, moderate or highly active disease [37]. FC could serve as a screening for inflammation, prior to colonoscopy, as well as supplement information relevant for treatment. Research on CgA in IBS patients has provided somewhat conflicting results. Serum CgA levels were found to be normal in the majority of a sample of IBS-D patients, while around 7% of them (N = 15) showed elevated levels of serum CgA (>60 u/L). In 8 of those patients CgA levels normalized at follow-up, while tumors were detected in 2 of the patients [38]. In another study comparing patients with different IBS subtypes, no differences in serum CgA were found between IBS-D, IBS-C and healthy controls [39]. Finally, a sample of patients with self-reported food hypersensitivity, 89% of whom met ROME II criteria for IBS, had lower serum CgA levels than healthy controls [40]. It would seem that CgA could be helpful in excluding tumors as a possible cause of the symptoms IBS patients present with. Health related quality of life (HRQoL) is an important outcome measure in IBS, and research shows it is related to both the severity of physical symptoms as well as psychological symptom severity. Thus, quality of life can be regarded as two separate constructs, physical and mental HRQoL. Physical HRQoL refers to physical limitations in everyday functioning which are a result of bodily pain or low general health, while mental HRQoL reflects functional limitations resulting from negative mood, or poor mental and social functioning [41]. Compared to healthy controls, IBS patients have significantly lower quality of life scores [42], as do IBD patients [43]. When comparing the two patient groups, they show similarly reduced quality of life [43]. If the physical and mental components of HRQoL are taken into account, IBD patients show lower physical HRQoL scores, but there are no differences between these groups in mental HRQoL [44]. The difference in physical HRQoL is most likely the result of a difference in symptom severity, which is underlined by inflammation and structural changes in IBD patients. Considering that IBD patients in remission with IBS-like symptoms who have higher FC levels also have lower HRQoL than patients without IBS-like symptoms [35], it is possible that low-grade inflammation can lead to symptom exacerbation and a consequential reduction in HRQoL in IBS patients as well.
Empirical data Forty-eight outpatients with irritable bowel syndrome (age M = 45.20, SD = 14.15; 76% females) completed a set of psychosocial measures including State-Trait Anxiety Inventory (STAI-T), Visceral Sensitivity Index (VSI), Beck Depression Inventory (BDI), IBS quality of life Inventory (IBS-36) and Short Form-36 Health Survey (SF-36). In addition, the patients filled out a symptom severity diary for 14 days. The symptom severity score was calculated as the average intensity of present symptoms over the period of measurement. The patients’ FC and serum CgA levels were also obtained.
Please cite this article in press as: Pletikosic S et al. Fecal Calprotectin and serum chromogranin A as potential biomarkers of irritable bowel syndrome symptom severity. Med Hypotheses (2015), http://dx.doi.org/10.1016/j.mehy.2015.06.008
S. Pletikosic et al. / Medical Hypotheses xxx (2015) xxx–xxx
It is important to note that no CgA was found in almost 46% of the sample, while data was not available for 29% of the sample. In the rest of the sample (N = 12) CgA levels ranged from 6 to 163 u/L. We found elevated CgA levels (>60 u/L) [39] in 4 patients. Although 40% of the sample tested negatively for FC, the rest of the sample presented with varying FC levels, ranging from 31 lg/g to 300 lg/g. Twelve patients had FC levels above 50 lg/g, of whom only 3 patients had FC levels above 100 lg/g. In order to determine the relationship between biological markers and IBS severity correlational analyses were performed. As we expected, CgA did not correlate with FC, because it predominantly serves as neuroendocrine tumor marker while FC is used as an inflammation marker. However, CgA showed no significant correlation with any other measure used, thus no other analyses were performed. On the other hand, the level of FC significantly correlated with the physical component of HRQoL (r48 = .42, p < .01). In addition, one-way ANOVA’s were performed to test possible differences in psychosocial measures depending on the patient’s FC status (less than 30 lg/g, from 31 to 50 lg/g, more than 51 lg/g). The analysis showed only one significant difference. Patients with the highest levels of FC had significantly lower physical component of HRQoL (PC HRQoL) compared to the other two groups of patients, which can be seen in Fig. 1. Consequences of the hypothesis This preliminary data shows that serum CgA was not detected at all, or it was present in insignificant levels, in the majority of the sample (91%), thus it can be useful in eliminating endocrine tumors as the cause of reported symptoms. CgA did not offer any additional relevant information for IBS symptom severity. This is in line with previous findings. Although some researchers found reduced CgA cell density in IBS patients compared to healthy controls, there were no differences in CgA plasma levels [39]. It would seem that because CgA levels reflect the total endocrine activity of the body, they are not specific or sensitive enough to have any clinical value for the evaluation of symptom severity or disease progress in IBS. Contrary to CgA, FC levels seem to be clinically relevant for evaluating IBS patients. Again, most IBS patients (75%) had undetectable or clinically insignificant levels of FC, indicating that low-grade inflammation is not a significant contributor to their disease etiology. Additionally, patients with values above the clinical cut-off (50 lg/g) [34] had a significantly lower physical quality of life. This indicates that FC not only serves as a good marker of low-grade inflammation, but helps identify patients with more severe physical limitations due to bodily pain and low physical
Fig. 1. Differences in PC HRQoL depending on FC status.
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and general health. It is interesting to note that patients above and below the cut-off for FC did not differ in the mental component of HRQoL or any other psychological measure. These findings support the clinical importance of FC in IBS. In conclusion, CgA could be included in the IBS diagnostic procedure in order to exclude the existence of endocrine tumors. On the other hand, FC should be included to detect the existence of inflammation. The inclusion of FC in IBS diagnosis has several other advantages. First, bearing in mind that a pro-inflammatory state can aggravate symptoms of IBS and decrease patients’ HRQoL it is of great importance to detect inflammation as a possible cause of IBS symptoms. Second, blood and stool tests are much more acceptable for patients compared to invasive procedures. Third, the effectiveness of therapy and disease severity could be easily tracked through time. Finally, differentiating between patients with predominant psychological disturbances from patients with predominantly inflammatory causes would lead to more adequate and timely treatment for both groups of patients. This is especially important for patients with low-grade inflammation who could benefit from anti-inflammatory medication not only in symptom reduction but also indirectly in the improvement of their quality of life. Of course, this does not imply we should abandon symptom-based criteria for IBS but only that such additional measures of potential low-grade inflammation could be useful for determining the underlying mechanisms of symptom generation and perpetuation [45]. Conflict of interest Authors declare no conflict of interest. References [1] Brandt LJ, Chey WD, Foxx-Orenstein AE, et al. An evidence-based position statement on the management of irritable bowel syndrome. Am J Gastroenterol 2009;104(Suppl. 1):S1–S35. [2] El-Salhy M, Mazzawi T, Gundersen D, Hausken T. Chromogranin A cell density in the rectum of patients with irritable bowel syndrome. Mol Med Rep 2012;6:1223–5. [3] Fichna JMAS. Brain–gut interactions in IBS. Front Pharmacol 2012;3:127. [4] Porcelli P, Todarello O. Psychological factors affecting functional gastrointestinal disorders. Adv Psychosom Med 2007;28:34–56. [5] Spiller R, Aziz Q, Creed F, et al. Guidelines on the irritable bowel syndrome: mechanisms and practical management. Gut 2007;56:1770–98. [6] van der Veek PP, Dusseldorp E, van Rood YR, Masclee AA. Testing a biobehavioral model of irritable bowel syndrome. Eur J Gastroenterol Hepatol 2010;22:412–9. [7] Clarke G, Quigley EM, Cryan JF, Dinan TG. Irritable bowel syndrome: towards biomarker identification. Trends Mol Med 2009;15:478–89. [8] Cremon C, Gargano L, Morselli-Labate AM, et al. Mucosal immune activation in irritable bowel syndrome: gender-dependence and association with digestive symptoms. Am J Gastroenterol 2009;104:392–400. [9] Guilarte M, Santos J, de Torres I, et al. Diarrhoea-predominant IBS patients show mast cell activation and hyperplasia in the jejunum. Gut 2007;56:203–9. [10] Ortiz-Lucas M, Saz-Peiro P, Sebastian-Domingo JJ. Irritable bowel syndrome immune hypothesis. Part one: the role of lymphocytes and mast cells. Rev Esp Enferm Dig 2010;102:637–47. [11] Cho HS, Park JM, Lim CH, et al. Anxiety, depression and quality of life in patients with irritable bowel syndrome. Gut Liver 2011;5:29–36. [12] Kovacs Z, Kovacs F. Depressive and anxiety symptoms, dysfunctional attitudes and social aspects in irritable bowel syndrome and inflammatory bowel disease. Int J Psychiatry Med 2007;37:245–55. [13] Sugaya N, Nomura S. Relationship between cognitive appraisals of symptoms and negative mood for subtypes of irritable bowel syndrome. Biopsychosoc Med 2008;2:9. [14] Tosic-Golubovic S, Miljkovic S, Nagorni A, Lazarevic D, Nikolic G. Irritable bowel syndrome, anxiety, depression and personality characteristics. Psychiatr Danub 2010;22:418–24. [15] DiBonaventura M, Sun SX, Bolge SC, Wagner JS, Mody R. Health-related quality of life, work productivity and health care resource use associated with constipation predominant irritable bowel syndrome. Curr Med Res Opin 2011;27:2213–22. [16] Huang WW, Zhou FS, Bushnell DM, Diakite C, Yang XH. Cultural adaptation and application of the IBS-QOL in China: a disease-specific quality-of-life questionnaire. Qual Life Res 2007;16:991–6.
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Please cite this article in press as: Pletikosic S et al. Fecal Calprotectin and serum chromogranin A as potential biomarkers of irritable bowel syndrome symptom severity. Med Hypotheses (2015), http://dx.doi.org/10.1016/j.mehy.2015.06.008