Age-related decline in rectal mucosal lymphocytes and mast cells

The human colon: Evidence for degenerative changes during aging and the physiological consequences

BACKGROUND

The incidence of constipation increases among the elderly (>65 years), while abdominal pain decreases. Causes include changes in lifestyle (e.g., diet and reduced exercise), disease and medications affecting gastrointestinal functions. Degenerative changes may also occur within the colo-rectum. However, most evidence is from rodents, animals with relatively high rates of metabolism and accelerated aging, with considerable variation in time course. In humans, cellular and non-cellular changes in the aging intestine are poorly investigated.

PURPOSE

To examine all available studies which reported the effects of aging on cellular and tissue functions of human isolated colon, noting the region studied, sex and age of tissue donors and study size. The focus on human colon reflects the ability to access full-thickness tissue over a wide age range, compared with other gastrointestinal regions. Details are important because of natural human variability. We found age-related changes within the muscle, in the enteric and nociceptor innervation, and in the submucosa. Some involve all regions of colon, but the ascending colon appears more vulnerable. Changes can be cell- and sublayer-dependent. Mechanisms are unclear but may include development of "senescent-like" and associated inflammaging, perhaps associated with increased mucosal permeability to harmful luminal contents. In summary, reduced nociceptor innervation can explain diminished abdominal pain among the elderly. Degenerative changes within the colon wall may have little impact on symptoms and colonic functions, because of high "functional reserve," but are likely to facilitate the development of constipation during age-related challenges (e.g., lifestyle, disease, and medications), now operating against a reduced functional reserve.

Alterations in metabolic pathways: a bridge between aging and weaker innate immune response

Aging is a time-dependent progressive physiological process, which results in impaired immune system function. Age-related changes in immune function increase the susceptibility to many diseases such as infections, autoimmune diseases, and cancer. Different metabolic pathways including glycolysis, tricarboxylic acid cycle, amino acid metabolism, pentose phosphate pathway, fatty acid oxidation and fatty acid synthesis regulate the development, differentiation, and response of adaptive and innate immune cells. During aging all these pathways change in the immune cells. In addition to the changes in metabolic pathways, the function and structure of mitochondria also have changed in the immune cells. Thereby, we will review changes in the metabolism of different innate immune cells during the aging process.

Mast cell evaluation in gastrointestinal biopsies: should we be counting? A critical review and practical guide for the surgical pathologist

Mast cells are residents of the tubular gastrointestinal (GI) tract, where they play an important role in host defence and other vital functions. Dysregulation of mast cells has been implicated in the pathogenesis of several neoplastic, inflammatory, and functional disorders, some of which may manifest with GI symptoms. Surgical pathologists must therefore confront when and how to evaluate GI biopsies for mast cells, and whether such decisions should be based on morphologic criteria, clinical context, or direct request from clinical colleagues. The pathologist's role in evaluation of mast cell infiltrates is best defined in the diagnosis of systemic mastocytosis, where the utility of morphologic assessment coupled with ancillary studies is well established. In contrast, in nonneoplastic mast cell disorders such as mast cell activation syndrome, irritable bowel syndrome, or so-called 'mastocytic enterocolitis', a role for histopathology, if any, is controversial. Despite this, pathologists have seen a sharp increase in requests for mast cell quantification in the latter setting, despite these requests not being supported by published evidence. Moreover, what constitutes a 'normal' number of mast cells in a luminal GI biopsy is not well established. As a result, there is considerable variation in how these requests are handled in practice. This review evaluates and summarizes the published evidence relating to mast cell evaluation in endoscopic GI biopsies in various clinical scenarios, with a goal of providing practical, evidence-based guidance for the surgical pathologist when approached with requests for mast cell quantification in GI biopsies.

Faecal Inflammatory Biomarkers and Gastrointestinal Symptoms after Bariatric Surgery: A Longitudinal Study

Background

Bariatric surgery induces various gastrointestinal (GI) modifications. We performed the first study longitudinally assessing the effect of bariatric surgery on faecal inflammatory biomarker levels and its relation with GI complaints.

Method

Faecal calprotectin, lactoferrin, and calgranulin-C levels were determined in 41 patients (34 Roux-en-Y [RYGB], 7 sleeves) before and at 6-16 weeks, 6 months, and 1 year after surgery. Changes in biomarker levels and percentage of patients above reference value were determined. Gastrointestinal symptom rating scale (GSRS) was used to assess GI complaints at corresponding time points. The postoperative relation between GSRS score and biomarker levels above reference value was investigated.

Results

After RYGB, median calprotectin levels are significantly higher (>188, 104-415 μg/g) than before surgery (40, 19-78 μg/g; p < 0.001), and over 90% of patients have levels above reference value 1 year after surgery. Median lactoferrin was 0.4 (0.2-1.6) μg/g before, and >5.9 (1.8-13.6) μg/g after surgery (p < 0.001). Median calgranulin-C levels remained far below the reference value and were 0.13 (0.05-0.24) μg/g before and <0.23 (0.06-0.33) μg/g after surgery. Similar results were found after sleeve gastrectomy. No difference was seen in GSRS score for patients with calprotectin and lactoferrin levels above reference values.

Conclusion

Faecal inflammatory biomarkers calprotectin and lactoferrin, but not calgranulin-C, rise above reference values shortly after bariatric surgery and remain elevated in the majority of patients. The discrepancy between calprotectin and calgranulin-C levels suggests no GI inflammation. Furthermore, patients after RYGB with biomarkers above the population reference value do not seem to have more GI complaints.

Infiltration of Mast Cells in Scalp Biopsies of Patients with Alopcia Areata or Androgenic Alopecia Versus Healthy Individuals: A Case Control Study

BACKGROUND

Alopecia areata (AA) and androgenic alopecia (AGA) are of the most common types of alopecias. Recently, the role of mastcells in inflammatory diseases has become the focus of many studies. However, few studies have been conducted on their role in AA and AGA. Therefore, our study aimed to quantitatively evaluate the presence of mastcells in the AA and AGA specimens.

MATERIALS AND METHODS

Three groups of AA, AGA, and healthy control were studied (each group with 20 subjects). Patients were randomly selected from those referred to the dermatology clinics of Shahid Beheshti University. Specimens were obtained from the scalp, and perifollicular and perivascular areas were investigated.

RESULTS

Significantly higher perifollicular and perivascular mastcell counts were seen in both AGA and AA groups as compared to healthy control (P<0.001 for both). Moreover, AA patients had more frequent perivascular mastcells than the AGA group (P=0.042). Among patients aged <40 years, perifollicular and perivascular mastcell counts were not significantly different among three groups; however, subjects over 40 years of age in both groups had significantly more perifollicular and perivascular mastcells than healthy participants. There was a significant positive correlation between disease severity and mast cell counts in both perifollicular and perivascular areas in AA patients (P=0.001 for both).

CONCLUSION

There is a significantly increased infiltration of mastcells in AA and AGA patients, and this increase is age and severity dependent. Moreover, the increase in mastcell proliferation is more dominant in AA patients.

Inflammatory cell distribution in colon mucosa as a new tool for diagnosis of irritable bowel syndrome: A promising pilot study

BACKGROUND

Currently, there are no histological criteria to diagnose irritable bowel syndrome (IBS). Our aims were (i) to examine the distribution of inflammatory cells in the colon of healthy and IBS subjects and (ii) to find histological diagnosis criteria for IBS.

METHODS

Colonic biopsies were taken from four distinct regions of the colon from 20 controls (HC) and 11 patients with IBS (4 with constipation (IBS-C) and 7 with diarrhea (IBS-D) and embedded in paraffin. Macrophages, mast cells, eosinophils, and T lymphocytes were immunostained and positive cells counted.

KEY RESULTS

In both HC and IBS patients, global cellularity decreased from the cecum to the rectum (P < .01) which is attributed to reduced number of macrophages (P < .05) and eosinophils (P < .001) but not T cells. Mast cells were reduced in IBS (P < .05) but not in HC, particularly in IBS-D (P < .05). Results showed higher number of macrophages in the left colon of IBS subjects than HC (P < .05).

CONCLUSION & INFERENCES

Here we report a decreasing gradient of immune cells from the cecum to the rectum of the human colon. Although global cellularity cannot be used to distinguish between IBS and HC, closer analysis of macrophages and mast cells may be useful markers to confirm IBS histologically and to differentiate between IBS-C and IBS-D when clinical presentation alternates between constipation and diarrhoea. This pilot study remains to be confirmed with greater number of patients.

Fecal Calprotectin

Calprotectin is a 36kDa member of the S100 family of proteins. It is derived predominantly from neutrophils and has direct antimicrobial effects and a role within the innate immune response. Calprotectin is found in various body fluids in proportion to the degree of any existing inflammation and its concentration in feces is about six times that of plasma. Measurement of fecal calprotectin is a useful surrogate marker of gastrointestinal inflammation. It has a high negative predictive value in ruling out inflammatory bowel disease (IBD) in undiagnosed, symptomatic patients and a high sensitivity for diagnosing the disease making it useful as a tool for prioritising endoscopy. In patients with known IBD, fecal calprotectin can be a useful tool to assist management, providing evidence of relapse or mucosal healing to enable therapy to be intensified or reduced. There are a number of commercial calprotectin assays with marked difference in performance as judged by external quality assessment and at present no standardised reference material exists. Various factors may affect results including age, medication and day to day variation. Laboratories should therefore be mindful of the characteristics of their own assay and factors that may affect results.

Randomized clinical trial on the effect of a multispecies probiotic on visceroperception in hypersensitive IBS patients

BACKGROUND

Irritable bowel syndrome (IBS) is characterized by heterogeneous pathophysiology and low response to treatment. Up to 60% of IBS patients suffers from visceral hypersensitivity, which is associated with symptom severity and underlying pathophysiological mechanisms. Recently, positive effects of probiotics in IBS have been reported, but overall the response was modest. We performed a study in IBS patients, characterized by visceral hypersensitivity measured with the rectal barostat, aiming to assess the effect of 6 weeks of multispecies probiotic mix on visceral pain perception.

METHODS

We conducted a randomized, placebo-controlled, double-blind trial in forty Rome III IBS patients with visceral hypersensitivity. Prior to intake, patients kept a 2-week symptom diary and underwent a rectal barostat measurement. When hypersensitivity was confirmed, participation was allowed and patients received a multispecies probiotic with in vitro proven potential beneficial effects on mechanisms contributing to visceral hypersensitivity (six different probiotic strains; 10(9)  cfu/g), or a placebo product of one sachet (5 g) per day for 6 weeks. At the end of the intervention period, visceroperception and symptoms were reassessed.

KEY RESULTS

Thirty-five patients completed the trial. The percentage of patients with visceral hypersensitivity decreased significantly in the probiotic and placebo group (76.5% and 71.4%, respectively; N.S. between groups). Improvement in pain scores and mean symptom score did not differ between the probiotic and placebo group.

CONCLUSIONS & INFERENCES

In this placebo-controlled trial in IBS patients with visceral hypersensitivity, no significant effect of a multispecies probiotic on viscerperception was observed. The study has been registered in the US National Library of Medicine (http://www.clinicaltrials.gov, NCT00702026).

Persistent abdominal symptoms in US adults after short-term stay in Mexico

BACKGROUND

Postinfectious irritable bowel syndrome (PI-IBS) has been reported as a complication of bacterial diarrhea including travelers' diarrhea (TD). This study assessed the role of TD among US students in Mexico in triggering the onset of persistent abdominal symptoms (PAS) and IBS.

METHODS

We conducted a 6-month follow-up of a cohort of 817 US students in Mexico as short-term study to assess the frequency of PAS and IBS. Using Rome II criteria for IBS, groups of students with PAS were then categorized as PI-IBS if they met the symptom criteria for IBS or as suffering from functional abdominal disorder (FAD) if they did not meet the criteria.

RESULTS

FAD and IBS were commonly found in US students 6 months after leaving Mexico. Important variables in their development were younger adult age, longer stays in Mexico and occurrence of acute diarrhea while in Mexico. Diarrhea while in Mexico occurred more commonly for those later diagnosed with FAD, 101/196 (52%), relative risk (RR) = 1.5 [confidence interval (CI) 1.2-1.8; p = 0.001]; IBS, 20/32 (63%), RR = 2.5 (CI 1.2-5.0; p = 0.007); and PAS (FAD + IBS), 121/228 (53%), RR = 1.5 (CI 1.2-1.8; p < 0.001) compared with subjects who had experienced diarrhea while in Mexico but were not diagnosed with PAS at 6 months, 227/589 (39%). Diarrhea caused by heat-labile enterotoxin-producing enterotoxigenic Escherichia coli or Providencia ssp. demonstrated a greater risk of developing PAS.

CONCLUSIONS

PAS occurred commonly in a subset of younger adult travelers who stayed longer in Mexico and experienced acute diarrhea while there. Further studies with this cohort will focus on host genetic associations with the development of PAS.

Colonic mucosal mediators from patients with irritable bowel syndrome excite enteric cholinergic motor neurons

BACKGROUND

Mediators released in the mucosal milieu have been suggested to be involved in visceral hypersensitivity and abdominal pain in patients with irritable bowel syndrome (IBS). However, their impact on myenteric neurons remains unsettled.

METHODS

Mucosal biopsies were obtained from the descending colon of patients with IBS and controls. Mucosal mast cells were identified immunohistochemically. The impact of spontaneously released mucosal mediators on guinea pig electrically stimulated longitudinal muscle myenteric plexus (LMMP) preparations was assessed in vitro by means of selective receptor antagonists and inhibitors.

KEY RESULTS

Patients with IBS showed an increased mast cell count compared with controls. Application of mucosal mediators of IBS to LMMPs potentiated cholinergic twitch contractions, an effect directly correlated with mast cell counts. Enhanced contractions were inhibited by 50.3% with the prostaglandin D2 antagonist BW A868C, by 31.3% and 39% with the TRPV1 antagonists capsazepine and HC-030031, respectively, and by 60.5% with purinergic P2X antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid. Conversely, the serotonin1-4, histamine1-3, tachykinin1-3 receptor blockade, and serine protease inhibition had no significant effect.

CONCLUSIONS & INFERENCES

Colonic mucosal mediators from patients with IBS excite myenteric cholinergic motor neurons. These effects were correlated with mast cell counts and mediated by activation of prostanoid receptors, TRPV1, and P2X receptors. These results support the role of mucosal inflammatory mediators and mast cell activation in altered motor function of IBS.

Analysis of colonic mucosa mast cell count in patients with chronic diarrhea

BACKGROUND/AIM

Chronic diarrhea is defined as a decrease in fecal consistency lasting for four or more weeks. Prevalence of this complication in the general population is 5%. Mast cells that play an important role in the regulation of gastrointestinal visceral sensitivity and vascular permeability may be involved in functional chronic diarrhea. In this study we tried to evaluate mast cells density in colonic mucosa of patients with chronic diarrhea.

PATIENTS AND METHODS

50 patients with chronic diarrhea and 50 persons as control group were investigated. All specimens were immunohistochemically stained for mast cell tryptase (MCT) with monoclonal mouse anti-human MCT as well as toluidine blue. Mean number of mucosal mast cells were counted in 10 high power microscopic fields of patients and control groups.

RESULTS

In patients group (age range, 15-78 years; 26 females), the number of mast cells per high power field in the immunohistochemistry staining was 21.3 ± 4.8 compared to 14.2 ± 3.4 in the control group (age range, 18-78 years; 24 females) [P < 0.001]. Also number of mast cells in toluidine blue staining was 10.3 ± 3.6 per high power field in cases and 7.1 ± 2.4 in the control group (P < 0.001).

CONCLUSION

Elevated number of colonic mast cells exist in patients with chronic diarrhea. Further research should be considered on application of these findings for new therapeutic opportunities.

Increase of colonic mast cells in obstructed defecation and their relationship with enteric glia

BACKGROUND

Mast cells are involved in visceral hypersensitivity and motor activity of the gastrointestinal tract. However, there is almost no information concerning mast cells in constipated patients.

AIMS

The purpose of this study was to investigate mast cells distribution in all colonic layers in controls and severely constipated patients with obstructed defecation.

METHODS

Full-thickness specimens from colons of patients undergoing surgery for obstructed defecation due to refractoriness to other therapeutic interventions (n = 11), compared to controls, were obtained and the number of mast cells (evaluated by specific monoclonal antibodies) were counted in the whole viscus and in the various colonic segments (cecum, ascending, transverse, descending, and sigmoid).

RESULTS

Compared to controls, constipated patients had significantly higher numbers of mast cells, both as an overall number and in single colonic segments. This increase was especially evident in the mucosa and submucosa. Mast cells were homogeneously represented in the various segment of the large bowel, in both controls and patients. Degranulated mast cells were found to be close to enteric glial cells and glial filaments.

CONCLUSIONS

Colonic mast cells are increased in obstructed defecation patients. This might represent a vicariating mechanism to the impaired colonic propulsive activity of these patients.

Colonic mast cells in controls and slow transit constipation patients

BACKGROUND

There is recent evidence that mast cells may play important roles in the gut, especially concerning visceral hypersensitivity and motor activity. However, most data are only available for clinical conditions characterised by diarrhoea, where MC have chiefly investigated in the mucosal layer of the colon and there is almost no information concerning constipation.

AIM

To investigate mast cells distribution in all colonic layers in controls and severely constipated patients.

METHODS

Full-thickness specimens from colons of patients undergoing surgery for slow transit constipation (n=29), compared with controls, were obtained and the number of mast cells (evaluated by specific monoclonal antibodies) counted as a whole and in single colonic segments (caecum, ascending, transverse, descending and sigmoid).

RESULTS

Compared with controls, constipated patients revealed significantly higher number of mast cells, both as overall number and in single colonic segments. The distribution of mast cells resulted fairly homogeneous in the various segment of the large bowel, in both controls and patients, and no significant difference in the percentage of degranulated cells was found between groups.

CONCLUSIONS

Colonic mast cells display a homogeneous distribution within the viscus. This cell population is shown to increase in severely constipated patients, which might represent a mechanism trying to compensate for the impaired propulsive activity of these patients.

Intestinal serotonin release, sensory neuron activation, and abdominal pain in irritable bowel syndrome

OBJECTIVES

Serotonin (5-hydroxytryptamine, 5-HT) metabolism may be altered in gut disorders, including in the irritable bowel syndrome (IBS). We assessed in patients with IBS vs. healthy controls (HCs) the number of colonic 5-HT-positive cells; the amount of mucosal 5-HT release; their correlation with mast cell counts and mediator release, as well as IBS symptoms; and the effects of mucosal 5-HT on electrophysiological responses in vitro.

METHODS

We enrolled 25 Rome II IBS patients and 12 HCs. IBS symptom severity and frequency were graded 0-4. 5-HT-positive enterochromaffin cells and tryptase-positive mast cells were assessed with quantitative immunohistochemistry on colonic biopsies. Mucosal 5-HT and mast cell mediators were assessed by high-performance liquid chromatography or immunoenzymatic assay, respectively. The impact of mucosal 5-HT on electrophysiological activity of rat mesenteric afferent nerves was evaluated in vitro.

RESULTS

Compared with HCs, patients with IBS showed a significant increase in 5-HT-positive cell counts (0.37 ± 0.16% vs. 0.56 ± 0.26%; P=0.039), which was significantly greater in patients with diarrhea-predominant IBS vs. constipation-predominant IBS (P=0.035). Compared with HCs, 5-HT release in patients with IBS was 10-fold significantly increased (P < 0.001), irrespective of bowel habit, and was correlated with mast cell counts. A significant correlation was found between the mucosal 5-HT release and the severity of abdominal pain (r(s)=0.582, P=0.047). The area under the curve, but not peak sensory afferent discharge evoked by IBS samples in rat jejunum, was significantly inhibited by the 5-HT₃ receptor antagonist granisetron (P<0.005).

CONCLUSIONS

In patients with IBS, 5-HT spontaneous release was significantly increased irrespective of bowel habit and correlated with mast cell counts and the severity of abdominal pain. Our results suggest that increased 5-HT release contributes to development of abdominal pain in IBS, probably through mucosal immune activation.

Numbers and distribution of immune cells in the tunica mucosa of the small and large intestine of full-thickness biopsies from healthy pet cats

In this study, CD3(+) T lymphocytes and IgA(+) , IgG(+) and IgM(+) plasma cells were quantified in the tunica mucosa of the intestinal tract of 12 pet cats without gastrointestinal diseases. The study included full-thickness biopsies of the duodenum, jejunum, ileum and colon. The distribution and quantification of CD3(+) T cells, IgA(+) , IgG(+) and IgM(+) plasma cells within the intestinal tunica mucosa was performed by using immunohistochemical methods and computer-aided morphometry. CD3(+) T cells were significantly prominent in the villi and their numbers increased from duodenum to ileum but decreased towards the colon. The predominant type of plasma cells was IgA(+) cells, followed by IgM(+) cells. The number of IgG(+) cells was generally low compared to the other plasma cell types investigated. The results of the vertical distribution showed that IgA(+) and IgM(+) plasma cells were most numerous in the lower crypt areas, whilst IgG(+) plasma cells accumulated in the upper crypt region with a decline towards the villi and the lower crypt areas of control cats. All types of plasma cells showed a general decline from the duodenum towards the caudal sections of the intestinal tract regarding the horizontal distribution of plasma cells. This study provides a comprehensive overview on the vertical and horizontal distribution and the number of CD3(+) T cells and IgA(+) , IgG(+) and IgM(+) plasma cells in the intestinal tunica mucosa of pet cats.

Severity of Giardia infection associated with post-infectious fatigue and abdominal symptoms two years after

BACKGROUND

A high rate of post-infectious fatigue and abdominal symptoms two years after a waterborne outbreak of giardiasis in Bergen, Norway in 2004 has previously been reported. The aim of this report was to identify risk factors associated with such manifestations.

METHODS

All laboratory confirmed cases of giardiasis (n = 1262) during the outbreak in Bergen in 2004 received a postal questionnaire two years after. Degree of post-infectious abdominal symptoms and fatigue, as well as previous abdominal problems, was recorded. In the statistical analyses number of treatment courses, treatment refractory infection, delayed education and sick leave were used as indices of protracted and severe Giardia infection. Age, gender, previous abdominal problems and symptoms during infection were also analysed as possible risk factors. Simple and multiple ordinal logistic regression models were used for the analyses.

RESULTS

The response rate was 81% (1017/1262), 64% were women and median age was 31 years (range 3-93), compared to 61% women and 30 years (range 2-93) among all 1262 cases. Factors in multiple regression analysis significantly associated with abdominal symptoms two years after infection were: More than one treatment course, treatment refractory infection, delayed education, bloating and female gender. Abdominal problems prior to Giardia infection were not associated with post-infectious abdominal symptoms. More than one treatment course, delayed education, sick leave more than 2 weeks, and malaise at the time of infection, were significantly associated with fatigue in the multiple regression analysis, as were increasing age and previous abdominal problems.

CONCLUSION

Protracted and severe giardiasis seemed to be a risk factor for post-infectious fatigue and abdominal symptoms two years after clearing the Giardia infection.

Infection, inflammation, and the irritable bowel syndrome

Gastrointestinal infection is ubiquitous worldwide though the pattern of infection varies widely. Poor hygiene and lack of piped water is associated with a high incidence of childhood infection, both viral and bacterial. However in developed countries bacterial infection is commoner in young adults. Studies of bacterial infections in developed countries suggest 75% of adults fully recover, however around 25% have long lasting changes in bowel habit and a smaller number develop the irritable bowel syndrome (IBS). Whether the incidence is similar in developing countries is unknown. Post-infective IBS (PI-IBS) shares many features with unselected IBS but by having a defined onset allows better definition of risk factors. These are in order of importance: severity of initial illness, smoking, female gender and adverse psychological factors. Symptoms may last many years for reasons which are unclear. They are likely to include genetic factors controlling the immune response, alterations in serotonin signaling, low grade mucosal inflammation maintained by psychological stressors and alterations in gut microbiota. As yet there are no proven specific treatments, though 5HT(3) receptor antagonists, anti-inflammatory agents and probiotics are all logical treatments which should be examined in large well-designed randomised placebo controlled trials.

Age-related faecal calprotectin, lactoferrin and tumour M2-PK concentrations in healthy volunteers

Objective

Measurement of the faecal markers calprotectin, lactoferrin and tumour M2-PK has been reported to be useful in the diagnosis and management of a range of gastrointestinal disorders in both children and adults. The aim of this study was to investigate the requirement for age-related reference ranges.

Methods

Faecal samples were obtained from 132 healthy subjects and analysis of calprotectin, lactoferrin and tumour M2-PK performed using commercially available enzyme-linked immunosorbent assay.

Results

In the healthy subjects median concentrations were as follows: for calprotectin – 2–9 y, 34 μg/g, 10–59 y, 22 μg/g and ≥60 y, 27 μg/g; for lactoferrin – 2–9 y, 2.2 μg/g, ≥10 y, 0.5 μg/g; and for tumour M2-PK all subjects <1 U/mL. Significant differences between age groups for different markers resulted in the following age-related reference ranges: calprotectin – 2–9 y, <166 μg/g, 10–59 y, <51 μg/g, ≥60 y, <112 μg/g; lactoferrin – 2–9 y, <29 μg/g, ≥10 y <4.6 μg/g.

Conclusion

In healthy individuals, we found there to be variation in the faecal inflammatory markers calprotectin and lactoferrin with age. For both calprotectin and lactoferrin children aged 2–9 y had significantly higher concentrations than subjects aged ≥10 y. For calprotectin but not lactoferrin, adults ≥60 years had a higher concentration than those aged 10–59 y. There was no change with age in the metabolomic marker faecal tumour M2-PK in healthy subjects. The knowledge of age-related reference ranges in healthy subjects is important to fully interpret changes in gastrointestinal disease.

Post-infectious irritable bowel syndrome

Post-infectious irritable bowel syndrome (PI-IBS) is a common disorder wherein symptoms of IBS begin after an episode of acute gastroenteritis. Published studies have reported incidence of PI-IBS to range between 5% and 32%. The mechanisms underlying the development of PI-IBS are not fully understood, but are believed to include persistent sub-clinical inflammation, changes in intestinal permeability and alteration of gut flora. Individual studies have suggested that risk factors for PI-IBS include patients’ demographics, psychological disorders and the severity of enteric illness. However, PI-IBS remains a diagnosis of exclusion with no specific disease markers and, to date, no definitive therapy exists. The prognosis of PI-IBS appears favorable with spontaneous and gradual resolution of symptoms in most patients.

Mucosal immune activation in irritable bowel syndrome: gender-dependence and association with digestive symptoms

OBJECTIVES

Immune activation may be involved in the pathogenesis of irritable bowel syndrome (IBS). However, the relative magnitude of this immune component and its correlation with gender and gastrointestinal complaints in IBS patients remains poorly elucidated.

METHODS

We enrolled 48 IBS patients, with either diarrhea or constipation, 12 patients with microscopic colitis, 20 patients with ulcerative colitis, and 24 healthy controls. Colonic immunocytes were identified with quantitative immunohistochemistry on mucosal biopsies. Gastrointestinal symptoms were assessed using a validated questionnaire.

RESULTS

IBS patients showed a significant 72% increase in mucosal immune cells compared to controls (P<0.001). Further analyses showed that increased immune cells were present in 50% of the IBS patients. The magnitude of the immune infiltrate in IBS was significantly lower than that of microscopic colitis or ulcerative colitis (42% and 124% increases vs. IBS, respectively; P<0.001). Compared with controls, IBS patients had increased numbers of CD3+, CD4+, and CD8+ T cells and mast cells (P<0.001). Compared to male IBS patients, female IBS patients had greater numbers of mast cells (P=0.066), but lower numbers of CD3+ and CD8+ T cells (P=0.002 and <0.001, respectively). Mucosal mast cell infiltration of IBS patients was significantly associated with abdominal bloating frequency (P=0.022) and with symptoms of dysmotility-like dyspepsia (P=0.001), but not ulcer-like dyspepsia.

CONCLUSIONS

A large subset of IBS patients shows gender-dependent mucosal infiltration of immunocytes that correlates with abdominal bloating and dysmotility-like dyspepsia. These results provide the rationale for considering immune mechanisms as a pathophysiological component in a subset of IBS patients.

Low risk of irritable bowel syndrome after Clostridium difficile infection

OBJECTIVE

The incidence of postinfectious irritable bowel syndrome (IBS) ranges between 4% and 32% of individuals after bacterial or parasitic infection. This study analyzed IBS symptoms in hospitalized patients three months after a symptomatic Clostridium difficile infection.

PATIENTS AND METHODS

All patients with a proven, symptomatic C difficile infection identified in the department of bacteriology over a four-month period were considered for enrolment. Patients were excluded in cases of pre-existing IBS or other organic gastrointestinal diseases. Patients completed both modified Talley and Rome II questionnaires within five days of clinical improvement with metronidazole and at three months postinfection, when stools were cultured and C difficile toxins were examined to exclude ongoing infection.

RESULTS

Twenty-three patients were evaluated three months after infection with C difficile. Just after infection, 15 patients were symptom free, whereas eight patients exhibited symptoms suggestive of IBS. Three months after infection, 22 patients remained symptom free, whereas one patient presented with symptoms indicative of IBS. That female patient had a prolonged infection without vomiting.

CONCLUSIONS

We have shown that while transient functional bowel disorder occurred in 34.7% of patients (eight of 23 patients) recently infected with C difficile, only 4.3% of patients (one of 23 patients) had symptoms indicative of IBS after three months (ie, postinfectious IBS). Because an age-related reduction in immune responsiveness has been documented, it can be speculated that the low incidence of postinfectious IBS may be explained by the older age of the study population. Therefore, it cannot be excluded that the findings may be different in younger patients.

Distribution of mast cell subtypes and immune cell populations in canine intestines: Evidence for age-related decline in T cells and macrophages and increase of IgA-positive plasma cells

The distribution and numbers of leucocytes and mast cells (MC) in the canine gastrointestinal tract of three different age groups was investigated immunhistochemically. In all age groups, CD3+ T cells were more prominent in the villus region than in the crypt areas without differences between intestinal segments, whereas macrophages were more randomly distributed. Kresylecht-violet and tryptase-positive MC were prominent in pericrypt regions with statistic significances. Chymase-bearing mast cells, IgA-, IgG- and IgM-containing cells did not show significant differences in their distribution but, except for IgG-positive cells, subjective trends with increasing numbers towards the crypts exist. The reasons for the distribution of T cells, macrophages, immunoglobulin-containing cells and mast cells are not clear. Lamina propria CD3+ T cells and macrophages significantly decreased whilst a significant increase of IgA-containing plasma cells with increasing age was found. For mast cell subtypes, IgG- and IgM-containing cells no significant changes in numbers with increasing age exist.

Role of infection in irritable bowel syndrome

Infection by pathogenic organisms leads to mucosal damage and disruption of the gut's extensive commensal flora, factors which may lead to prolonged bowel dysfunction. Six to 17% of unselected irritable bowel syndrome (IBS) patients believe their symptoms began with an infection, which is supported by prospective studies showing a 4%-31% incidence of postinfectious IBS-(PI) following bacterial gastroenteritis. The wide range of incidence can be accounted for by differences in risk factors, which include in order of magnitude; severity of initial illness > bacterial toxigenicity > hypochondriasis, depression and neuroticism, and adverse life events in the previous 3 months. PI-IBS has been reported after Campylobacter, Salmonella, and Shigella infections. Serial biopsies after Campylobacter jejuni gastroenteritis show an initial inflammatory infiltrate, with an increase in enterochromaffin (EC) cells, which in most cases subsides over the next 6 months. Those who go on to develop IBS show increased numbers of EC and lymphocyte cell counts at 3 months compared with those who do not develop IBS. Interleukin-1beta mRNA levels are increased in the mucosa of those who develop PI-IBS, who also show increased gut permeability. Recover can be slow, with approximately 50% still having symptoms at 5 years. Recent studies suggest an increase in peripheral blood mononuclear cell cytokine production in unselected IBS, an abnormality that may be ameliorated by probiotic treatment. The role of small-bowel bacterial overgrowth in IBS is controversial, but broad-spectrum antibiotics do have a temporary benefit in some patients. More acceptable long-term treatments altering gut flora are awaited with interest.

Histopathological alterations in irritable bowel syndrome

Irritable bowel syndrome is a common disorder defined by a symptom complex including abdominal pain and altered bowel habit. The etiopathogenesis appears to be multifactorial and to involve altered gastrointestinal motor function, enhanced perception of visceral stimuli and psychosocial factors. More recently a role for mucosal immune activation has been suggested. Routine histologic examination reveals no mucosal abnormality in the majority of cases but quantitative histological, immunohistochemical and ultrastructural analyses reveal subtle morphologic changes involving lymphocytes, mast cells, enterochromaffin cells and enteric nerves. The recent appreciation of these changes has led to new hypotheses linking central and enteric nervous systems to immune processes. This review highlights the spectrum of morphologic changes that occur in irritable bowel syndrome, examines their relationship to the pathophysiology of irritable bowel syndrome and considers their relevance to daily pathology practice.

Functional gastrointestinal disorders and mast cells: implications for therapy

The pathophysiology of functional gastrointestinal disorders is poorly understood. Accepted common mechanisms include psychosocial factors, abnormal gastrointestinal motility and disturbed visceral sensory perception, but the underlying causes remain unclear. Mast cells (MCs) are immunocytes widely distributed throughout the gastrointestinal tract. Several stimuli (e.g. allergens, neuropeptides and stress) lead to MC activation with consequent mediator release (e.g. histamine, tryptase and prostanoids). The MC mediators interact with nerves supplying the gut leading to altered gut physiology and increased sensory perception. The intestinal mucosa of irritable bowel syndrome patients contains on average an increased number of MCs. These cells release an increased amount of mediators in close vicinity to mucosal innervation. The MC activation and their close proximity to nerve fibres is correlated with the severity of perceived abdominal painful sensations. These data provide a strong basis for considering MCs as important participants in visceral hypersensitivity and pain perception in irritable bowel syndrome. Inhibition of MC function may ameliorate irritable bowel symptoms. Novel drugs with an increased potential in the control of MC function (e.g., anti-IgE antibodies, the intracellular protein tyrosine kinase inhibitor Syk) and mediator release (e.g., second generation antihistamines, proteinase-activated receptor antagonists) may be useful pharmacological tools for these common disorders.

Abnormalities of 5-hydroxytryptamine metabolism in irritable bowel syndrome

BACKGROUND & AIMS

5-hydroxytryptamine-3 (5-HT 3 ) receptor antagonists improve symptoms in patients with diarrhea-predominant irritable bowel syndrome (D-IBS), 5-HT 4 agonists help those with constipation-predominant IBS (C-IBS). These data suggest excess or deficiency in 5-HT in D-IBS or C-IBS, respectively. Mucosal 5-HT-containing enterochromaffin cells (EC) are increased in postinfectious IBS (PI-IBS). Our aim was to define the postprandial release of 5-HT in PI-IBS and C-IBS patients and to relate this to mucosal 5-HT turnover.

METHODS

Fifteen PI-IBS patients with diarrhea-predominant symptoms, 15 C-IBS patients, and 15 healthy controls underwent serial (platelet-poor) plasma 5-HT measurement for 3 hours after a standard 520-kcal meal. Rectal biopsy specimens were assayed for 5-HT and its metabolite 5-hydroxindoleacetic acid (5-HIAA). Colonic transit was measured using radio-opaque markers.

RESULTS

Colonic transit was prolonged in C-IBS patients (mean +/- SEM) (49.4 +/- 3.8 h) compared with PI-IBS (26.7 +/- 4.5) and control patients (34.1 +/- 4.5) ( P < .02). Release of 5-HT assessed by area under the curve (AUC) of platelet-poor plasma 5-HT from 0 to 180 minutes postprandially was significantly lower in C-IBS patients (2593 +/- 309 mmol/L . min) compared with P-IBS (5623 +/- 721) and control patients (4822 +/- 598) ( P < .001). PI-IBS patients showed significantly higher peak postprandial plasma 5-HT values (median, range) (71.7, 43.4-125.3) ng/L compared with C-IBS patients (31.2, 15.2-40.5) and control patients (43.6, 26.7-50.1) ( P < .01). Mucosal 5-HT turnover as assessed by mucosal 5-HIAA/5-HT ratio was decreased in both C-IBS and PI-IBS patients, .14 (.01-.6) and .21 (.02-2.5), respectively, compared with control patients 1.12 (.17-3.1) ( P < .002).

CONCLUSIONS

C-IBS patients show impaired postprandial 5-HT release whereas PI-IBS patients have higher peak levels, abnormalities that may be related to their different symptoms.