Mucosal mast cells are pivotal elements in inflammatory bowel disease that connect the dots: Stress, intestinal hyperpermeability and inflammation

The Power of Psychobiotics in Depression: A Modern Approach through the Microbiota-Gut-Brain Axis: A Literature Review

The microbiota-gut-brain (MGB) axis is a complex communication network linking the gut, microbiota, and brain, influencing various aspects of health and disease. Dysbiosis, a disturbance in the gut microbiome equilibrium, can significantly impact the MGB axis, leading to alterations in microbial composition and function. Emerging evidence highlights the connection between microbiota alterations and neurological and psychiatric disorders, including depression. This review explores the potential of psychobiotics in managing depressive disorders, emphasizing their role in restoring microbial balance and influencing the MGB axis. Psychobiotics exhibit positive effects on the intestinal barrier, immune response, cortisol levels, and the hypothalamic-pituitary-adrenal (HPA) axis. Studies suggest that probiotics may serve as an adjunct therapy for depression, especially in treatment-resistant cases. This review discusses key findings from studies on psychobiotics interventions, emphasizing their impact on the gut-brain axis and mental health. The increasing acceptance of the expanded concept of the MGB axis underscores the importance of microorganisms in mental well-being. As our understanding of the microbiome's role in health and disease grows, probiotics emerge as promising agents for addressing mental health issues, providing new avenues for therapeutic interventions in depressive disorders.

Neurotensin agonist PD149163 modulates lipopolysaccharide induced inflammation and oxidative stress in the female reproductive system of mice

Inflammation-mediated reproductive health problems in females have become an emerging concern. The present investigation was aimed to elucidate the efficacy of the PD149163, agonist of the type I neurotensin receptor, in preventing/ameliorating the lipopolysaccharide (LPS) induced inflammation of the female reproductive system of the mice. Female Swiss Albino Mice (8 weeks old) were maintained in three groups (6/group): Group I as Control, Group II and Group III were exposed to intraperitoneal (i.p) LPS (1 mg/kg bw) for 5 days followed by treatment with PD149163 (100 μg/kg BW i.p.) to Group III (LPS + PD) for 28 days. After termination of the experiment on 29th day, plasma levels of inflammatory cytokines, LH, FSH, estradiol, corticosterone, oxidative stress effects in the ovary and histopathological study of the ovary and uterine horn were done. LPS-induced inflammation of the ovary and uterine horn was ameliorated/prevented by PD149163 as reflected in the reduced histopathological scores, significant elevation of the plasma anti-inflammatory cytokine IL-10 and decrease of the pro inflammatory cytokines TNF-α and IL-6. Significant decrease of lipid peroxide, increase of antioxidant defense enzymes, Superoxide dismutase and Catalase in the ovary indicated reduction of oxidative stress. The plasma levels of the reproduction related hormones and corticosterone were restored. PD149163 acts as an anti-inflammatory and anti-oxidative agent in modulation of inflammation in the female reproductive system (ovary & uterine horn). These findings suggest that the therapeutic potential of the analogs of neurotensin including PD149163 should be explored for the treatment of the female reproductive health issues.

Investigating intestinal mast cell dynamics during acute heat stress in growing pigs

Objectives were to examine the temporal pattern of intestinal mast cell dynamics and the effects of a mast cell stabilizer (ketotifen [Ket]) during acute heat stress (HS) in growing pigs. Crossbred barrows (n = 42; 32.3 ± 1.9 kg body weight [BW]) were randomly assigned to 1 of 7 environmental-therapeutic treatments: (1) thermoneutral (TN) control (TNCon; n = 6), (2) 2 h HS control (2 h HSCon; n = 6), (3) 2 h HS + Ket (2 h HSKet; n = 6); (4) 6 h HSCon (n = 6), (5) 6 h HSKet (n = 6), (6) 12 h HSCon (n = 6), or (7) 12 h HSKet (n = 6). Following 5 d of acclimation to individual pens, pigs were enrolled in two experimental periods (P). During P1 (3 d), pigs were housed in TN conditions (21.5 ± 0.8 °C) for the collection of baseline measurements. During P2, TNCon pigs remained in TN conditions for 12 h, while HS pigs were exposed to constant HS (38.1 ± 0.2 °C) for either 2, 6, or 12 h. Pigs were euthanized at the end of P2, and blood and tissue samples were collected. Regardless of time or therapeutic treatment, pigs exposed to HS had increased rectal temperature, skin temperature, and respiration rate compared to their TNCon counterparts (1.9 °C, 6.9° C, and 119 breaths/min; P < 0.01). As expected, feed intake and BW gain markedly decreased in HS pigs relative to their TNCon counterparts (P < 0.01). Irrespective of therapeutic treatment, circulating corticotropin-releasing factor decreased from 2 to 12 h of HS relative to TNCon pigs (P < 0.01). Blood cortisol increased at 2 h of HS (2-fold; P = 0.04) and returned to baseline by 6 h. Plasma histamine (a proxy of mast cell activation) remained similar across thermal treatments and was not affected by Ket administration (P > 0.54). Independent of Ket or time, HS increased mast cell numbers in the jejunum (94%; P < 0.01); however, no effects of HS on mast cell numbers were detected in the ileum or colon. Jejunum and ileum myeloperoxidase area remained similar among treatments (P > 0.58) but it tended to increase (12%; P = 0.08) in the colon in HSCon relative to TNCon pigs. Circulating lymphocytes and basophils decreased in HSKet relative to TN and HSCon pigs (P ≤ 0.06). Blood monocytes and eosinophils were reduced in HS pigs relative to their TNCon counterparts (P < 0.01). In summary, HS increased jejunum mast cell numbers and altered leukocyte dynamics and proinflammatory biomarkers. However, Ket administration had no effects on mast cell dynamics measured herein.

Neuro-Immuno-Psychological Aspects of Chronic Urticaria

Urticaria is a condition characterized by the development of itchy wheals (hives), angioedema, or both. The pathophysiology of chronic spontaneous urticaria (CSU) is still poorly understood. It is suggested that there is no dominant and independent mechanism of CSU; however, there are different immunological and non-immunological abnormalities that act simultaneously or/and follow each other resulting in clinical symptoms. The latest hypothesis points out that mast cells (MCs) to be activated via autoantibodies in autoallergic or autoimmune mechanism mediators released from degranulated MCs are responsible for the vasoactive and neurospecific effect in CSU. According to many clinical observations, it is suggested that psychological stress can be both a triggering factor in the onset of CSU and a modulating one in the course of the disease and therapy effectiveness. Of importance, the mechanistic background of the psychological stress response in the skin has not yet been fully elucidated. However, of note, a variety of inflammatory mediators, neuropeptides, and neurotransmitters facilitate this phenomenon. This review presents recent findings on the neuro-immuno-psychological aspects of CSU, highlighting an emerging role of neuro-immune interactions. It also points out the usefulness of psychological tools employment for the baseline diagnosis of perceived stress level and the presence of its symptoms. Furthermore, it proposes the implementation of non-invasive interventions to reduce psychological stress and anxiety. A bio-psycho-social approach including psychological support and patient education seems to be as important as traditional pharmacotherapy for CSU. It facilitates the effective control of active disease and a prolonged remission time in this disease.

Neurotensin modulation of lipopolysaccharide induced inflammation of gut-liver axis: Evaluation using neurotensin receptor agonist and antagonist

Lipopolysaccharide (LPS), a toxic component of the cell wall of Gram-negative bacteria, is a potent immune stressor. LPS-induced inflammation of the gut-liver axis is well demonstrated. Neurotensin (NTS), a tri-decapeptide present in the gastrointestinal tract, has anti-inflammatory, anti-oxidative, and growth-promoting properties. This study elucidated the efficacy of PD149163, the type I NTS receptor agonist (NTS₁) in the modulation of LPS-induced inflammation of the gut-liver axis of mice. Young-adult female mice (Age: 8 weeks; BW: 25 ± 2.5 g) were maintained in six groups (6/group); Group I as control and Group II, III & IV were exposed to LPS (1 mg/kg BW/Day; i.p.) for five days. LPS pre-exposed Group III and Group IV mice were treated with NTS₁ agonist PD149163 (100 μg/kg BW i.p.) and antagonist SR48692 (0.5 mg/kg BW i.p.) respectively for 28 days. Group V and Group VI mice were exposed to only PD149163 and only SR48692 respectively with the doses as mentioned above for 28 days. Group I and LPS-exposed Group II mice were also maintained four weeks without further treatment. Histopathology revealed LPS-induced inflammation of the gut and liver. Significant elevation of plasma TNF-α and IL-6 and serum ALT and AST reflected as biomarkers of inflammation. Oxidative stress on both organs was distinct from decreased glutathione reductase and increased lipid peroxidation. PD149163 but not SR48692 ameliorated LPS-induced inflammation in both gut and liver counteracting inflammatory responses and oxidative stress. The use of NTS agonists including PD149163 could be exploited for therapeutic intervention of inflammatory diseases including that of the gut-liver axis.

Role of the duodenal microbiota in functional dyspepsia

BACKGROUND

Functional dyspepsia (FD) is a common and debilitating gastrointestinal disorder attributed to altered gut-brain interactions. While the etiology of FD remains unknown, emerging research suggests the mechanisms are likely multifactorial and heterogenous among patient subgroups. Small bowel motor disturbances, visceral hypersensitivity, chronic microinflammation, and increased intestinal tract permeability have all been linked to the pathogenesis of FD. Recently, alterations to the gut microbiome have also been implicated to play an important role in the disease. Changes to the duodenal microbiota may either trigger or be a consequence of immune and neuronal disturbances observed in the disease, but the mechanisms of influence of small intestinal flora on gastrointestinal function and symptomatology are unknown.

PURPOSE

This review summarizes and synthesizes the literature on the link between the microbiota, low-grade inflammatory changes in the duodenum and FD. This review is not intended to provide a complete overview of FD or the small intestinal microbiota, but instead outline some of the key conceptual advances in understanding the interactions between altered gastrointestinal bacterial communities; dietary factors; host immune activation; and stimulation of the gut-brain axes in patients with FD versus controls. Current and emerging treatment approaches such as dietary interventions and antibiotic or probiotic use that have demonstrated symptom benefits for patients are reviewed, and their role in modulating the host-microbiota is discussed. Finally, suggested opportunities for diagnostic and therapeutic improvements for patients with this condition are presented.

Effect of L-Glutamine on Chylomicron Formation and Fat-Induced Activation of Intestinal Mucosal Mast Cells in Sprague-Dawley Rats

Glutamine (Gln) is required for intestinal mucosal homeostasis, and it can promote triglyceride absorption. The intestinal mucosal mast cells (MMCs) are activated during fat absorption. This study investigated the potential role of Gln on fat absorption-induced activation of MMCs in rats. Lymph fistula rats (n = 24) were studied after an overnight recovery with the infusion of saline only, saline plus 85 mM L-glutamine (L-Gln) or 85 mM D-glutamine (D-Gln), respectively. On the test day, rats (n = 8/group) were given an intraduodenal bolus of 20% Intralipid contained either saline only (vehicle group), 85 mM L-Gln (L-Gln group), or 85 mM D-Gln (D-Gln group). Lymph was collected hourly for up to 6 h for analyses. The results showed that intestinal lymph from rats given L-Gln had increased levels of apolipoprotein B (ApoB) and A-I (ApoA-I), concomitant with an increased spectrum of smaller chylomicron particles. Unexpectedly, L-Gln also increased levels of rat mucosal mast cell protease II (RMCPII), as well as histamine and prostaglandin D2 (PGD2) in response to dietary lipid. However, these effects were not observed in rats treated with 85 mM of the stereoisomer D-Gln. Our results showed that L-glutamine could specifically activate MMCs to degranulate and release MMC mediators to the lymph during fat absorption. This observation is potentially important clinically since L-glutamine is often used to promote gut health and repair leaky gut.

Mitochondrial DNA Release Contributes to Intestinal Ischemia/Reperfusion Injury

Mitochondria release many damage-associated molecular patterns (DAMPs) when cells are damaged or stressed, with mitochondrial DNA (mtDNA) being. MtDNA activates innate immune responses and induces inflammation through the TLR-9, NLRP3 inflammasome, and cGAS-STING signaling pathways. Released inflammatory factors cause damage to intestinal barrier function. Many bacteria and endotoxins migrate to the circulatory system and lymphatic system, leading to systemic inflammatory response syndrome (SIRS) and even damaging the function of multiple organs throughout the body. This process may ultimately lead to multiple organ dysfunction syndrome (MODS). Recent studies have shown that various factors, such as the release of mtDNA and the massive infiltration of inflammatory factors, can cause intestinal ischemia/reperfusion (I/R) injury. This destroys intestinal barrier function, induces an inflammatory storm, leads to SIRS, increases the vulnerability of organs, and develops into MODS. Mitophagy eliminates dysfunctional mitochondria to maintain cellular homeostasis. This review discusses mtDNA release during the pathogenesis of intestinal I/R and summarizes methods for the prevention or treatment of intestinal I/R. We also discuss the effects of inflammation and increased intestinal barrier permeability on drugs.

Protective effect of neurotensin receptor-1 agonist PD 149163 against lipopolysaccharide-induced gut toxicity in mice

The interaction between neuroendocrine and immune components of the gut maintains the organism's physical and psychological health. Its disruption may reflect in disease conditions such as inflammatory bowel disease (IBD) and mental illness. The lipopolysaccharide (LPS) disrupts the endocrine-immune homeostasis resulting in gut toxicity. The Neurotensin receptor-1 (NTR-1) agonist PD 149163 (PD) acts as an atypical antipsychotic drug in psychiatric illness, but its role in modulating gut pathophysiology remains unknown. Therefore, the aim of the present study was to evaluate the protective effect of PD against LPS-induced gut toxicity. Swiss albino female mice (12 weeks) were divided into six groups (n = 6/group): (I) Control, (II) LPS (1 mg/kg, for 5 days), (III) LPS (1 mg/kg, for 5 days)+PD low (100 µg/kg, for 21 days), (IV) LPS (1 mg/kg, for 5 days)+PD high (300 µg/kg, for 21 days), (V) PD low (100 µg/kg, for 21 days), and (VI) PD high (300 µg/kg, for 21 days). Drugs were given intraperitoneal in the morning. PD administration prevented the LPS-induced gut inflammation observed in damage of epithelial barrier, disruption of goblet cells, and condensation of lamina propria (LP). The LPS-induced oxidative stress characterized by decreased superoxide dismutase (SOD) activity and increased lipid hydroperoxide (LOOH) (p < 0.001 for both), and enhanced interleukine-6 (IL-6) & tumor necrosis factor-α (TNF-α) (p < 0.001 for both) as well as immunointensity of NT (p < 0.01) and NTR-1 (p < 0.05) were reversed and normalized to control after PD treatment. Thus, the anti-inflammatory, anti-oxidative, and cell proliferation properties of PD modulate the gut toxicity in LPS-challenged mice.

Quantitative Analysis of Intramucosal Mast Cells in Irritable Bowel Syndrome: A Comparison With Inflammatory Bowel Disease in Remission

GOAL

We aimed to study the density of intramucosal mast cells in histologically normal colonic mucosa biopsied from patients with a clinical diagnosis of irritable bowel syndrome (IBS).

BACKGROUND

Mast cell activation has been thought to implicate in the pathogenesis of inflammatory bowel disease (IBD). Whether it serves a role in the pathogenesis of IBS remains controversial.

STUDY

A total of 127 colonoscopic mucosal biopsies were immunohistochemically stained, including 51 IBS, 66 IBD, and 10 normal control samples. Intact mast cells were quantified in 3 high power fields (HPF) in areas showing the highest density.

RESULTS

CD117 was sensitive in detecting mast cells in colonic mucosa. The mast cell counts in all biopsies ranged from 2 to 60 per HPF (mean=17.5±7.2). The density of intramucosal mast cells were similar among IBS, IBD and normal control groups (P=0.6733). IBD in remission versus IBS (17.1±8.0 vs. 18.1±7.0; P=0.4804), Crohn disease versus ulcerative colitis (17.1±10.4 vs. 17.2±5.2; P=0.9463), IBS with diarrhea versus without diarrhea (19.5±6.3 vs. 16.8±6.9; P=0.1404). Forty biopsies (31.5%) showing ≥20 mast cells per HPF appeared to equally distribute among various disease groups (P=0.7283).

CONCLUSIONS

There is no significant difference in the number of intramucosal mast cells between IBS and IBD that show normal colonic biopsies. In IBS patients, the number of intramucosal mast cell does not correlate with symptoms. The mast cell count (≥20/HPF) is not a reliable criterion for the diagnosis of IBS or for the distinction between patients with IBS and those with IBD in remission.

The Potential Effects of Probiotics and ω-3 Fatty Acids on Chronic Low-Grade Inflammation

Chronic low-grade inflammation negatively impacts health and is associated with aging and obesity, among other health outcomes. A large number of immune mediators are present in the digestive tract and interact with gut bacteria to impact immune function. The gut microbiota itself is also an important initiator of inflammation, for example by releasing compounds such as lipopolysaccharides (LPS) that may influence cytokine production and immune cell function. Certain nutrients (e.g., probiotics, ω-3 fatty acids [FA]) may increase gut microbiota diversity and reduce inflammation. Lactobacilli and Bifidobacteria, among others, prevent gut hyperpermeability and lower LPS-dependent chronic low-grade inflammation. Furthermore, ω-3 FA generate positive effects on inflammation-related conditions (e.g., hypertriglyceridemia, diabetes) by interacting with immune, metabolic, and inflammatory pathways. Ω-3 FA also increase LPS-suppressing bacteria (i.e., Bifidobacteria) and decrease LPS-producing bacteria (i.e., Enterobacteria). Additionally, ω-3 FA appear to promote short-chain FA production. Therefore, combining probiotics with ω-3 FA presents a promising strategy to promote beneficial immune regulation via the gut microbiota, with potential beneficial effects on conditions of inflammatory origin, as commonly experienced by aged and obese individuals, as well as improvements in gut-brain-axis communication.

Association between Irritable Bowel Syndrome and Allergic Diseases: To Make a Case for Aeroallergen

Irritable bowel syndrome (IBS) is a functional gastrointestinal disease and the most common cause of prolonged abdominal pain and bowel disturbances in the developed world. While initially thought to be functional or psychosomatic in nature, IBS is now recognized as a heterogeneous group of conditions. A subset of IBS patients and patients with allergic diseases share some characteristic inflammatory features. In fact, atopic children show an increased likelihood of developing IBS as adults. Given these findings, a subset of IBS may be suffering from allergy-related gut diseases. In this review, we present the allergy-related comorbidities of IBS, including genetic, environmental, and immunologic factors. We discuss studies demonstrating an increased sensitization of IBS patients to aeroallergens compared to food allergens. We then postulate potential pathophysiological mechanisms underlying both IBS and aeroallergens in the gut, followed by potential implications in the screening and treatment of allergies in IBS patients.

Chronic Unpredictable Mild Stress in Rats Induces Colonic Inflammation

Chronic psychological stress is associated with an increased risk for relapse of inflammatory bowel diseases (IBD) and impedes the treatment of this condition. However, the impact of stress on the risk of IBD onset remains unclear. The goal of the present study was to examine whether chronic unpredictable mild stress (CUMS) could initiate or aggravate the onset of colon inflammation in rats which, in turn, would be capable of triggering bowel disease. We found that CUMS exposure increased infiltration of CD-45 positive cells and MPO activity, as well as augmented the expression of the inflammatory cytokines, IFN-γ and IL-6 within the colon of these rats. In addition, CUMS treatment changed the composition and diversity of gut microbiota and enhanced intestinal epithelial permeability, indicating the presence of a defect in the intestinal barrier. This CUMS-induced disruption of mucosal barrier integrity was associated with a reduction in expression of the tight junction protein, occludin 1, and an inhibition in mucosal layer functioning via reductions in goblet cells. Results from bacterial cultures revealed an increased presence of bacterial invasion after CUMS treatment as compared with that observed in controls. Thus, our data indicate that CUMS treatment induces alterations of the fecal microbiome and intestinal barrier defects, which facilitates bacterial invasion into colonic mucosa and further exacerbates inflammatory reactions within the colon. Accordingly, chronic stress may predispose patients to gastrointestinal infection and increase the risk of inflammation-related gut diseases.

On the role of corticosterone in behavioral disorders, microbiota composition alteration and neuroimmune response in adult male mice subjected to maternal separation stress

Experiencing psychosocial adversities in early life such as maternal separation (MS) increases the risk of psychiatric disorders. Immune-inflammatory responses have imperative roles in the pathophysiology of psychiatric disorders. MS relatively changes the composition of intestinal microbiota leading to an overactivation of the hypothalamic-pituitary-adrenal (HPA) axis, and subsequently increases the corticosterone level. In this study, we aimed to evaluate the role of corticosterone in behavioral changes and microbiota modifications in a mouse model of MS afflicted neuroinflammatory response in the hippocampus. For this purpose, 180 min of MS stress was applied to mice at postnatal day (PND) 2-14 followed by behavioral tests including forced swimming test (FST), splash test, open field test (OFT) and elevated plus maze (EPM) at PND 50-52. For evaluating the role of corticosterone, mice were subjected to adrenalectomy. Using real-time RT-PCR, the expression of inflammatory genes was determined in the hippocampus and colon tissues. We found that MS provoked depressive- and anxiety-like behaviors in adult male mice. In addition, MS was able to active a neuroimmune response in the hippocampus, motivate inflammation and histopathologic changes in the colon tissue and modify the composition of gut microbiota as well. Interestingly, our findings showed that adrenalectomy (decline in the corticosterone level), could modulate the above-mentioned negative effects of MS. In conclusion, our results demonstrated that overactivation of HPA axis and the subsequent increased level of corticosterone could act, possibly, as the deleterious effects of MS on behavior, microbiota composition changes and activation of neuroimmune response.

Intestinal hyperpermeability: a gateway to multi-organ failure?

In critically ill patients, disruption of intestinal epithelial cell function occurs due to exposure of the epithelium to toxic internal and external inflammatory stimuli, which are key factors that trigger sepsis and multi-organ dysfunction syndrome (MODS). A greater understanding of how trauma and gut failure lead to sepsis and progression to MODS is much needed. In this issue of the JCI, Armacki and colleagues identify mechanisms by which thirty-eight-negative kinase 1 (TNK1) promotes the progression from intestinal apoptosis and gut failure to bacterial translocation, sepsis, and MODS. Moreover, the results of this study suggest TNK1 as a potential therapeutic target to prevent sepsis and MODS.

Downregulation of iNOS, IL-1β, and P2X7 Expression in Mast Cells via Activation of PAR4 Contributes to the Inhibition of Visceral Hyperalgesia in Rats

Protease-activated receptor 4 (PAR4) is implicated in the inhibition of visceral hyperalgesia. In the present study, the effects of PAR4 activation on visceral hypersensitivity and expression of inflammatory mediators, including interleukin-1β (IL-1β), P2RX7 purinergic receptor (P2X7), inducible nitric oxide synthase (iNOS), and tryptase, in mast cells (MCs) were investigated via in vivo and in vitro studies. The numbers of tryptase-positive MCs with extensive PAR4, P2X7, and iNOS expression were increased in the colons of visceral hyperalgesia rats compared with controls. Intracolonic administration of PAR4-activating peptide (PAR4-AP) significantly attenuated the visceral hypersensitivity to colorectal distention and reduced the iNOS, IL-1β, P2X7, and tryptase protein and mRNA levels in the colonic mucosa. Treatment of rat bone marrow MCs (BMMCs) with PAR4-AP also reduced the iNOS, IL-1β, P2X7, and tryptase protein and mRNA levels. ERK1/2 and p38 activators (t-butylhydroquinone, tBHQ, and U-46619) reversed the suppressive effect of PAR4 activation on IL-1β and iNOS expression, whereas ERK1/2 and p38 inhibitors (PD98059 and SB203580) reversed the suppressive effect of PAR4 activation on P2X7 and tryptase expression. Our results indicate that the downregulation of inflammatory mediators, including iNOS, IL-1β, P2X7, and tryptase, in MCs that are mediated by PAR4 activation could inhibit visceral hyperalgesia via the mitogen-activated protein kinase (MAPK) signal pathway.

Th9 Cells: Probable players in ulcerative colitis pathogenesis

T lymphocytes represent an important part of adaptive immune system undertaking different functions to regulate immune responses. CD4+ T cells are the most important activator cells in inflammatory conditions. Depending on the type of induced cells and inflamed sites, expression and activity of different subtypes of helper T cells are changed. Recent studies have confirmed the existence of a new subset of helper T lymphocytes called Th9. Naive T cells can differentiate into Th9 subtypes if they are exposed simultaneously by interleukin (IL) 4 and transforming growth factor β and also secondary activation of a complicated network of transcription factors such as interferon regulatory factor 4 (IRF4) and Smads which are essential for adequate induction of this phenotype. Th9 cells specifically produce interleukin 9 and their probable roles in promoting intestinal inflammation are being investigated in human subjects and experimental models of ulcerative colitis (UC). Recently, infiltration of Th9 cells, overexpression of IL-9, and certain genes associated with Th9 differentiation have been demonstrated in inflammatory microenvironment of UC. Intestinal oversecretion of IL-9 protein is likely to break down epithelial barriers and compromise tolerance to certain commensal microorganisms which leads to inflammation. Th9 pathogenicity has not yet been adequately explored in UC and they are far from being considered as inflammatory cells in this milieu, therefore precise understanding the role of these newly identified cells in particular their potential role in gut pathogenesis may enable us to develop novel therapeutic approaches for inflammatory bowel disease. So, this article tries to discuss the latest knowledge on the above-mentioned field.

Preschoolers With Allergic Diseases Have an Increased Risk of Irritable Bowel Syndrome When Reaching School Age

OBJECTIVES

The aim of the study was to systemically investigate the risk of subsequent irritable bowel syndrome (IBS) in children with antecedent allergic diseases in a population-based case-control study in Taiwan.

METHODS

We evaluated 11,242 children (age range: 7-18 years) with IBS and 44,968 age- and sex-matched control subjects who had been examined between 2000 and 2008. IBS odds ratios were calculated for children with antecedent allergic diseases, including allergic conjunctivitis, allergic rhinitis, asthma, atopic dermatitis, urticaria, and food allergy.

RESULTS

Children with antecedent allergic diseases had a greater risk of IBS than did control subjects (P < 0.001). Among the 6 evaluated diseases, the highest adjusted odds ratio of 1.78 was observed with allergic rhinitis (95% confidence interval [CI], 1.69-1.87). With 2 or more allergic diseases, the adjusted odds ratios increased to 2.06 (95% CI, 1.93-2.19) for all subjects, 2.07 (95% CI, 1.88-2.28) for girls, and 2.18 (95% CI, 2.02-2.35) for children 12 years or older.

CONCLUSIONS

Preschoolers with a history of allergic disease had an increased risk of subsequent IBS development upon reaching school age. This risk increased in the presence of concurrent allergic disease and a higher clinical allergy burden.

Antibiotics Suppress Activation of Intestinal Mucosal Mast Cells and Reduce Dietary Lipid Absorption in Sprague-Dawley Rats

BACKGROUND & AIMS

The gut microbiota affects intestinal permeability and mucosal mast cells (MMCs) responses. Activation of MMCs has been associated with absorption of dietary fat. We investigated whether the gut microbiota contributes to the fat-induced activation of MMCs in rats, and how antibiotics might affect this process.

METHODS

Adult male Sprague-Dawley rats were given streptomycin and penicillin for 4 days (n = 6-8) to reduce the abundance of their gut flora, or normal drinking water (controls, n = 6-8). They underwent lymph fistula surgery and after an overnight recovery were given an intraduodenal bolus of intralipid. We collected intestinal tissues and lymph fluid and assessed activation of MMCs, intestinal permeability, and fat transport parameters.

RESULTS

Compared with controls, intestinal lymph from rats given antibiotics had reduced levels of mucosal mast cell protease II (produced by MMCs) and decreased activity of diamine oxidase (produced by enterocytes) (P < .05). Rats given antibiotics had reduced intestinal permeability in response to dietary lipid compared with controls (P < .01). Unexpectedly, antibiotics also reduced lymphatic transport of triacylglycerol and phospholipid (P < .01), concomitant with decreased levels of mucosal apolipoproteins B, A-I, and A-IV (P < .01). No differences were found in intestinal motility or luminal pancreatic lipase activity between rats given antibiotics and controls. These effects were not seen with an acute dose of antibiotics or 4 weeks after the antibiotic regimen ended.

CONCLUSIONS

The intestinal microbiota appears to activate MMCs after the ingestion of fat in rats; this contributes to fat-induced intestinal permeability. We found that the gut microbiome promotes absorption of lipid, probably by intestinal production of apolipoproteins and secretion of chylomicrons.

Expression of inducible nitric oxide synthase in mast cells contributes to the regulation of inflammatory cytokines in irritable bowel syndrome with diarrhea

BACKGROUND

Nitric oxide (NO) and mast cells (MCs) are possibly involved in the development of irritable bowel syndrome (IBS), but details on their role and interactions still remain undetermined. We aimed to investigate the expression of inducible NO synthase (iNOS) in MCs of the colon of IBS with diarrhea (IBS-D), and elucidated a potential role of NO in the differential regulation of cytokines in MCs.

METHODS

Colonic mucosal biopsies of 19 IBS-D patients and 16 healthy controls were collected. The expression of tryptase and iNOS was investigated by immunohistochemistry, Western blotting, and real-time PCR. Effects of NO on the expression of cytokines in rat bone marrow MCs (BMMCs) were examined using a cytokine array by NG-nitro-l-arginine methyl ester (L-NAME) treatment.

KEY RESULTS

Immunohistochemistry for tryptase revealed an increase in number of MCs with extensive iNOS expression in the colonic mucosa of IBS-D. Tryptase, iNOS and interleukin (IL)-1β mRNA and protein levels were upregulated in IBS-D compared with healthy controls. Specifically, a positive correlation between tryptase and iNOS protein expression was observed in the colon of IBS-D (r = 0.667, p < 0.05). Supernatant from IBS-D increased iNOS expression in BMMCs. Antibody array showed that agrin, beta-nerve growth factor, fractalkine, granulocyte-macrophage colony-stimulating factor, IL-1β, IL-1R6, IL-13, leptin, tumor necrosis factor alpha were suppressed, and cytokine-induced neutrophil chemoattractant (CINC)-1, CINC-2α, CINC-3, monocyte chemotactic protein-1, matrix metalloproteinase-8 were strongly produced in L-NAME treated BMMCs, comparable to levels in the control group.

CONCLUSIONS & INFERENCES

Our findings provide new evidence that NO is able to regulate many cytokines in MCs that may be involved in the development of IBS.

Concurrent Ulcerative Colitis and Neurofibromatosis Type 1: The Question of a Common Pathway

Patients with neurofibromatosis type 1 (NF1) are prone to the development of gastrointestinal stromal tumors, which may present clinically with hematochezia, obstruction, or abdominal pain. These symptoms are also commonly associated with the presentation of ulcerative colitis (UC). Within the past 5 years, there have been 2 reports of concurrent NF1 and UC and a common pathophysiologic pathway involving mast cells has been postulated. We present the case of a 15-year-old boy with a known history of NF1 who presented with 3 months of hematochezia and loose stools. A colonoscopy revealed pancolitis and histology demonstrating acute cryptitis, focal crypt abscesses, and architectural distortion consistent with UC. Due to the paucity of reported cases, the findings of both diseases in the same individual could reasonably be discounted as coincidence. However, in light of increasing reports of concurrent NF1 and UC, advances in characterizing the microenvironment within neurofibromas, and recent findings regarding potential shared genetic susceptibility, it is increasingly possible that the proposed common pathway is accurate. Our case adds to the literature and underscores the need for further investigation.

Towards a systems view of IBS

Despite an extensive body of reported information about peripheral and central mechanisms involved in the pathophysiology of IBS symptoms, no comprehensive disease model has emerged that would guide the development of novel, effective therapies. In this Review, we will first describe novel insights into some key components of brain-gut interactions, starting with the emerging findings of distinct functional and structural brain signatures of IBS. We will then point out emerging correlations between these brain networks and genomic, gastrointestinal, immune and gut-microbiome-related parameters. We will incorporate this new information, as well as the reported extensive literature on various peripheral mechanisms, into a systems-based disease model of IBS, and discuss the implications of such a model for improved understanding of the disorder, and for the development of more-effective treatment approaches in the future.

Therapeutic strategies for functional dyspepsia and irritable bowel syndrome based on pathophysiology

Functional gastrointestinal disorders (FGIDs) are common and distressing. They are so named because a defined pathophysiology in terms of structural or biochemical pathways is lacking. Traditionally FGIDs have been conceptualized as brain-gut disorders, with subgroups of patients demonstrating visceral hypersensitivity and motility abnormalities as well as psychological distress. However, it is becoming apparent that there are certain structural or biochemical gut alterations among subsets with the common FGIDs, most notably functional dyspepsia (FD) and irritable bowel syndrome (IBS). For example, a sodium channel mutation has been identified in IBS that may account for 2 % of cases, and subtle intestinal inflammation has been observed in both IBS and FD. Other research has implicated early life events and stress, autoimmune disorders and atopy and infections, the gut microbiome and disordered mucosal immune activation in patients with IBS or FD. Understanding the origin of symptoms in FGIDs will allow therapy to be targeted at the pathophysiological changes, not at merely alleviating symptoms, and holds hope for eventual cure in some cases. For example, there are promising developments in manipulating the microbiome through diet, prebiotics and antibiotics in IBS, and testing and treating patients for Helicobacter pylori infection remains a mainstay of therapy in patients with dyspepsia and this infection. Locally acting drugs such as linaclotide have been an advance in treating the symptoms of constipation-predominant IBS, but do not alter the natural history of the disease. A role for a holistic approach to patients with FGIDs is warranted, as brain-to-gut and gut-to-brain pathways appear to be activated.

Role of Corticotropin-releasing Factor in Gastrointestinal Permeability

The interface between the intestinal lumen and the mucosa is the location where the majority of ingested immunogenic particles face the scrutiny of the vast gastrointestinal immune system. Upon regular physiological conditions, the intestinal micro-flora and the epithelial barrier are well prepared to process daily a huge amount of food-derived antigens and non-immunogenic particles. Similarly, they are ready to prevent environmental toxins and microbial antigens to penetrate further and interact with the mucosal-associated immune system. These functions promote the development of proper immune responses and oral tolerance and prevent disease and inflammation. Brain-gut axis structures participate in the processing and execution of response signals to external and internal stimuli. The brain-gut axis integrates local and distant regulatory networks and super-systems that serve key housekeeping physiological functions including the balanced functioning of the intestinal barrier. Disturbance of the brain-gut axis may induce intestinal barrier dysfunction, increasing the risk of uncontrolled immunological reactions, which may indeed trigger transient mucosal inflammation and gut disease. There is a large body of evidence indicating that stress, through the brain-gut axis, may cause intestinal barrier dysfunction, mainly via the systemic and peripheral release of corticotropin-releasing factor. In this review, we describe the role of stress and corticotropin-releasing factor in the regulation of gastrointestinal permeability, and discuss the link to both health and pathological conditions.

Mast cells in human health and disease

Mast cells are primarily known for their role in defense against pathogens, particularly bacteria; neutralization of venom toxins; and for triggering allergic responses and anaphylaxis. In addition to these direct effector functions, activated mast cells rapidly recruit other innate and adaptive immune cells and can participate in "tuning" the immune response. In this review we touch briefly on these important functions and then focus on some of the less-appreciated roles of mast cells in human disease including cancer, autoimmune inflammation, organ transplant, and fibrosis. Although it is difficult to formally assign causal roles to mast cells in human disease, we offer a general review of data that correlate the presence and activation of mast cells with exacerbated inflammation and disease progression. Conversely, in some restricted contexts, mast cells may offer protective roles. For example, the presence of mast cells in some malignant or cardiovascular diseases is associated with favorable prognosis. In these cases, specific localization of mast cells within the tissue and whether they express chymase or tryptase (or both) are diagnostically important considerations. Finally, we review experimental animal models that imply a causal role for mast cells in disease and discuss important caveats and controversies of these findings.

Tachykinin peptide, substance P, and its receptor NK-1R play an important role in alimentary tract mucosal inflammation during cytotoxic therapy

The alimentary tract mucosal inflammation has been a topic of concern in oncology; though many modalities of treatment have been proposed for mucosal inflammation, the contributing adverse effects have severely affected the quality of life of patients. This review focuses on the importance of neurogenic peptide, Substance P and its receptor NK-1R in modulating the cascades of events in mucosal inflammation during cytotoxic therapy. There are various preclinical and clinical models showing increased expression of Substance P/NK-1R in ionizing radiation and chemotherapy, but only very few preclinical studies to our knowledge have highlighted or examined its role in mucosal inflammation. Hence, the importance of neuropeptide involved in the inflammatory events in mucosal inflammation in cytotoxic therapy could be a major breakthrough for future research purposes and treatment. The factors contributing to the severity of tissue reactions have been multietiogenic; thus, resultant treatment also has to be directed toward multiple contributing factors. This review also focuses on the significance of care strategy to be adopted in alimentary tract mucositis when multietiogenic factors are taken into consideration.

Stress and food allergy: mechanistic considerations

Recent years have seen a marked increase in food allergy prevalence among children, particularly in Western countries, that cannot be explained by genetic factors alone. This has resulted in an increased effort to identify environmental risk factors underlying food allergies and to understand how these factors may be modified through interventions. Food allergy is an immune-mediated adverse reaction to food. Consequently, considerations of candidate risk factors have begun to focus on environmental influences that perturb the healthy development of the emerging immune system during critical periods of development (eg, prenatally and during early childhood), particularly in the gut. Given that psychosocial stress is known to play an important role in other allergic and inflammatory diseases, such as asthma, its potential role in food allergy is a growing area of research. However, research to date has largely focused on animal studies. This review synthesizes relevant animal research and epidemiological data, providing proof of concept for moderating influences of psychological stress on food allergy outcomes in humans. Pathways that may underlie associations between psychosocial stress and the expression of food allergy are discussed.

Predictive factors of impaired quality of life in Korean patients with inactive inflammatory bowel disease: association with functional gastrointestinal disorders and mood disorders

BACKGROUND AND AIM

Inflammatory bowel disease is a chronic and relapsing inflammatory disorder of the intestine and has a great effect on patients' health-related quality of life (HRQOL). Some patients in remission are known to show functional gastrointestinal disorders (FGIDs) and mood disorders (MDs), which may also negatively impact HRQOL. The aim of this study was to evaluate predictors of impaired HRQOL in inactive inflammatory bowel disease (IBD) patients.

METHODS

Patients presenting a long-standing remission during the previous year completed questionnaires of EuroQol, Rome III criteria for FGID, and Hospital Anxiety and Depression Survey. Demographic data including age, sex, employment status, education, smoking, and location of residence were also collected.

RESULTS

Among the 513 patients with IBD, 226 (Crohn's disease 107 and ulcerative colitis 119, age 39.01±15.63, male 141) defined in remission were enrolled. Overall, 147 (65.0%) had at least 1 FGID with irritable bowel syndrome being the most common disorder (36.3%). Anxiety and depression were identified in 27.4% and 33.6%, respectively. Participants with FGID or MD had a significantly lower HRQOL status than those without disorders (P<0.01). Among various demographic and clinical variables, aged 40 or older [odds ratio (OR), 2.342; 95% confidence interval (CI), 1.195-4.590; P=0.01], irritable bowel syndrome (OR, 3.932; 95% CI, 1.937-7.982; P<0.01), and anxiety (OR, 2.423; 95% CI, 1.067-5.502; P=0.03) were significant independent predictors of impaired HRQOL in inactive IBD patients.

CONCLUSIONS

FGID and MD are common in Korean quiescent IBD patients. Appropriate management should be administered according to age of patients and presence of concomitant FGID and MD to improve patients' HRQOL.

Mast Cells in Adjacent Normal Colon Mucosa rather than Those in Invasive Margin are Related to Progression of Colon Cancer

OBJECTIVE

Mast cells (MC) reside in the mucosa of the digestive tract as the first line against bacteria and toxins. Clinical evidence has implied that the infiltration of mast cells in colorectal cancers is related to malignant phenotypes and a poor prognosis. This study compared the role of mast cells in adjacent normal colon mucosa and in the invasive margin during the progression of colon cancer.

METHODS

Specimens were obtained from 39 patients with colon adenomas and 155 patients with colon cancers treated at the Sun Yat-sen University Cancer Center between January 1999 and July 2004. The density of mast cells was scored by an immunohistochemical assay. The pattern of mast cell distribution and its relationship with clinicopathologic parameters and 5-year survival were analyzed.

RESULTS

The majority of mast cells were located in the adjacent normal colon mucosa, followed by the invasive margin and least in the cancer stroma. Mast cell count in adjacent normal colon mucosa (MCC(adjacent)) was associated with pathologic classification, distant metastases and hepatic metastases, although it was not a prognostic factor. In contrast, mast cell count in the invasive margin (MCC(invasive)) was associated with neither the clinicopathlogic parameters nor overall survival.

CONCLUSION

Mast cells in the adjacent normal colon mucosa were related to the progression of colon cancer, suggesting that mast cells might modulate tumor progression via a long-distance mechanism.

Review article: Associations between immune activation, intestinal permeability and the irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS), one of the most common gastrointestinal disorders, markedly impairing patients' quality of life. Drug development for IBS treatment has been hampered by the lack of understanding of IBS aetiology. In recent years, numerous data have emerged that suggest the involvement of immune activation in IBS, at least in a subset of patients.

AIM

To determine whether immune activation and intestinal permeabilisation are more frequently observed in IBS patients compared with healthy controls.

METHODS

The scientific bibliography was searched using the following keywords: irritable bowel syndrome, inflammation, immune activation, permeabilisation, intestine, assay, histology and human. The retrieved studies, including blood, faecal and histological studies, were analysed to provide a comprehensive and structured overview of the available data including the type of assay, type of inflammatory marker investigated or intestinal segment studied.

RESULTS

Immune activation was more frequently observed in IBS patients than in healthy controls. An increase in the number of mast cells and lymphocytes, an alteration in cytokine levels and intestinal permeabilisation were reported in IBS patients. No consistent changes in the numbers of B cells or enterochromaffin cells or in mucosal serotonin production were demonstrated.

CONCLUSIONS

The changes observed were modest and often heterogeneous among the studied population. Only appropriate interventions improving irritable bowel syndrome symptoms could highlight and confirm the role of immune activation in this pathophysiology.

Altered neuro-endocrine-immune pathways in the irritable bowel syndrome: the top-down and the bottom-up model

The interaction between the brain and the gut as a pathological mechanism of functional gastrointestinal disorders has been recently recognized in the pathophysiology of the irritable bowel syndrome. Communication between central nervous system and enteric nervous system is two-directional: the brain can influence the function of the enteric nervous system and the gut can influence the brain via vagal and sympathetic afferents. In patients with irritable bowel syndrome, symptoms may be caused by alterations either primarily in the central nervous system (top-down model), or in the gut (bottom-up model), or in a combination of both. The brain-gut axis may be stimulated by various stressors either directed to the central nervous system (exteroreceptive stress) or to the gut (interoceptive stress). Particularly, clinical evidence suggest that in complex and multifactorial diseases such as irritable bowel syndrome, psychological disorders represent significant factors in the pathogenesis and course of the syndrome. Neuroimaging techniques have shown functional differences between central process in healthy subjects and patients with irritable bowel syndrome. Moreover, a high prevalence of psychological/psychiatric disorders have been reported in IBS patients compared to controls. Several data also suggest an alteration of neuro-endocrine and autonomic output to the periphery in these patients. This review will examine and discuss the complex interplay of neuro-endocrine-immune pathways, closely associated with neuropsychiatric disorders.

Activation of rat intestinal mucosal mast cells by fat absorption

Previous studies have linked certain types of gut mucosal immune cells with fat intake. We determined whether fat absorption activates intestinal mucosal mast cells (MMC), a key component of the gut mucosal immune system. Conscious intestinal lymph fistula rats were used. The mesenteric lymph ducts were cannulated, and the intraduodenal (i.d.) tubes were installed for the infusion of Liposyn II 20% (an intralipid emulsion). Lymphatic concentrations of histamine, rat MMC protease II (RMCPII), a specific marker of rat intestinal MMC degranulation, and prostaglandin D(2) (PGD(2)) were measured by ELISA. Intestinal MMC degranulation was visualized by immunofluorescent microscopy of jejunum sections taken at 1 h after Liposyn II gavage. Intraduodenal bolus infusion of Liposyn II 20% (4.4 kcal/3 ml) induced approximately a onefold increase in lymphatic histamine and PGD(2), ∼20-fold increase in lymphatic RMCPII, but only onefold increase in peripheral serum RMCPII concentrations. Release of RMCPII into lymph increased dose dependently with the amount of lipid fed. In addition, i.d. infusion of long-chain triacylglycerol trilinolein (C18:2 n-6, the major composite in Liposyn II) significantly increased the lymphatic RMCPII concentration, whereas medium-chain triacylglycerol tricaprylin (C8:0) did not alter lymph RMCPII secretion. Immunohistochemistry image revealed the degranulation of MMC into lamina propria after lipid feeding. These novel findings indicate that intestinal MMC are activated and degranulate to release MMC mediators to the circulation during fat absorption. This action of fatty acid is dose and chain length dependent.

Brief report: "allergic symptoms" in children with Autism Spectrum Disorders. More than meets the eye?

Many children with Autism Spectrum Disorders (ASD) have either family and/or personal history of "allergic symptomatology", often in the absence of positive skin or RAST tests. These symptoms may suggest mast cell activation by non-allergic triggers. Moreover, children with mastocytosis or mast cell activation syndrome (MCAS), a spectrum of rare diseases characterized by increased number of activated mast cells in many organs, appear to have ASD at a rate tenfold higher (1/10 children) than that of the general population (1/100 children). Mast cell activation by allergic, infectious, environmental and stress-related triggers, especially perinatally, would release pro-inflammatory and neurotoxic molecules. We speculate these could disrupt the gut-blood-brain barriers, thus contributing to brain inflammation and ASD pathogenesis. Increased mast cell responsiveness may define at least a subgroup of ASD subjects, who could benefit from inhibition of mast cell activation.

Soluble mediators released from PI-IBS patients' colon induced alteration of mast cell: involvement of reactive oxygen species

BACKGROUND

Growing evidence suggests that patients with post-infectious irritable bowel syndrome (PI-IBS) have increased mast cell activation, and that mucosal soluble mediators are involved in the pathophysiology of visceral hyperalgesia. In addition, previous findings show that reactive oxygen species (ROS) and protease-activated receptors (PARs) are mediators of persistent hyperalgesia.

AIMS

This article aims to investigate: (1) the ability of soluble factors from colonic biopsies to active peritoneal mast cells (PMCs) in vitro; (2) whether the effects of PMCs degranulation induced by soluble mediators are related to PARs activation; and (3) the ability of phenyl N-tert-butylnitrone (PBN), a ROS scavenger, to modify these alterations.

METHODS

Supernatant (SUP) from colonic biopsies was collected and applied to PMCs for 12 h. Activation of PMCs was evaluated. The expression of PAR(2) in PMCs was examined by RT-PCR and double-immunofluorescence staining. PBN (10 mM) treatment was administered, then previous alterations were observed again.

RESULTS

Stimulation with SUP of PI-IBS led to an increase in activation of PMCs. PAR(2)mRNA expression was significantly increased in PMCs induced by SUP of PI-IBS compared to healthy subjects. After being treated by PBN, the SUP-induced enhancement of PMCs activities could be weakened, and PAR(2)mRNA expression was significantly decreased. A similar result of immunoreactivity for PAR(2) was observed in PMCs.

CONCLUSIONS

The study shows that ROS scavenger reverses the SUP of PI-IBS-induced enhancement of PMCs activities, and that these effects may be related to activation of PAR(2). These findings might pave the way to new therapeutic targets in PI-IBS.

Combination of allergic factors can worsen diarrheic irritable bowel syndrome: role of barrier defects and mast cells

OBJECTIVES

Recent evidence suggests a role for increased colonic permeability and mucosal mast cell (MC) mediators on symptoms related to the irritable bowel syndrome (IBS). Whether allergic factors (AFs) are involved in the pathophysiology of IBS is unclear. We addressed the question of the possible influence of an allergic background on IBS symptoms.

METHODS

We assessed paracellular permeability, mucosal MCs counts, and spontaneous release of tryptase of colonic biopsy specimens in 34 IBS patients and 15 healthy subjects. The severity of IBS was assessed through self-reported questionnaires. All individuals were tested for the presence of AF, including self-perception of adverse reaction to food, personal and familial history of atopic disease, elevated total or specific immunoglobulin E against food/inhalant antigens, blood eosinophilia, and skin tests.

RESULTS

IBS patients had significant enhanced colonic permeability, higher number of MCs, and spontaneous release of tryptase than healthy subjects. The severity of IBS was significantly correlated with colonic permeability (r=0.48, P=0.004), MCs counts (r=0.36, P=0.03), and tryptase (r=0.48, P=0.01). In 13 IBS patients (38.2%) having at least three AFs, symptoms scores, colonic permeability, MCs counts, and tryptase release by colonic biopsies were significantly higher than in those with less than three AFs. IBS patients with at least three AFs were more prone to diarrhea or alternating symptoms. None AF was found to be predictive of IBS severity.

CONCLUSIONS

In IBS patients, the presence of an allergic background correlates with a more severe disease and diarrhea predominance, possibly by enhancing mucosal MC activation and paracellular permeability.

Nutrient-induced inflammation in the intestine

PURPOSE OF REVIEW

To review our current understanding of the relationship between absorption of nutrients and intestinal inflammatory response.

RECENT FINDINGS

There is increasing evidence linking gut local inflammatory events with the intake of nutrients. Our recent studies, using the conscious lymph fistula rat model, demonstrate that fat absorption activates the intestinal mucosal mast cells. This is accompanied by a dramatic increase in the lymphatic release of mast cell mediators including histamine, rat mucosal mast cell protease II (RMCPII), as well as the lipid mediator prostaglandin D2 (PGD2). Clinical studies suggest that increased consumption of animal fat may play a role in the pathogenesis of inflammatory bowel disease. This impact of dietary fat may not be restricted to the gut but may extend to the whole body. There is evidence linking a high-fat diet-induced metabolic syndrome, with a low-grade chronic inflammatory state. In this review, we hope to convince the readers that fat absorption can have far reaching physiological and pathophysiological consequences.

SUMMARY

Understanding the relationship between nutrient absorption and intestinal inflammation is important. We need a better understanding of the interaction between enterocytes and the intestinal immune cells in nutrient absorption and the gut inflammatory responses.

Normal quantity and distribution of mast cells and eosinophils in the pediatric colon

The normal number and distribution of mast cells (MCs) and eosinophils in colonic mucosa are largely unknown. Accordingly, we examined colonic biopsies obtained during endoscopic examinations of pediatric patients. The study included 41 patients (21 males and 20 females). The mean age was 11.72 years (range 3.3-19.7 years). Patients were followed for a mean time of 23.4 months (range 12-50 months). Our results showed a gradual decrease in the number of eosinophils in the lamina propria from the cecum to the descending colon (14.2 ± 6.1 and 10.7 ± 5.6 eosinophils//high-power field [hpf], respectively), with another peak in the rectosigmoid (12.4 ± 6.1 eosinophils/hpf). Eosinophils within the surface and crypt epithelium were more commonly encountered in the cecum and the rectosigmoid. Eosinophils clusters were rare but were more frequently found in the cecum and rectosigmoid. The largest number of MCs was observed in the descending colon and the lowest in the rectosigmoid (17.56 ± 7.28 and 14.5 ± 6.35 MCs/hpf, respectively). No MCs were identified within the surface epithelium. Very rare MCs were observed within the crypt epithelium, with the highest number observed in the cecum (0.34 ± 0.53 MCs/hpf) and the lowest number observed in the descending colon (0.02 ± 0.16 MCs/hpf). More MCs were present in the cecum and descending colon of females vs males (P  =  0.02 and 0.04, respectively). Our results establish baseline gastrointestinal eosinophils and MC counts in various parts of the pediatric colon.

Need for a comprehensive medical approach to the neuro-immuno-gastroenterology of irritable bowel syndrome

Irritable bowel syndrome (IBS) is defined by the Rome III criteria as symptoms of recurrent abdominal pain or discomfort with the onset of a marked change in bowel habits with no evidence of an inflammatory, anatomic, metabolic, or neoplastic process. As such, many clinicians regard IBS as a central nervous system problem of altered pain perception. Here, we review the recent literature and discuss the evidence that supports an organic based model, which views IBS as a complex, heterogeneous, inter-dependent, and multi-variable inflammatory process along the neuronal-gut axis. We delineate the organic pathophysiology of IBS, demonstrate the role of inflammation in IBS, review the possible differences between adult and pediatric IBS, discuss the merits of a comprehensive treatment model as taught by the Institute of Functional Medicine, and describe the potential for future research for this syndrome.

Maternal separation as a model of brain-gut axis dysfunction

RATIONALE

Early life stress has been implicated in many psychiatric disorders ranging from depression to anxiety. Maternal separation in rodents is a well-studied model of early life stress. However, stress during this critical period also induces alterations in many systems throughout the body. Thus, a variety of other disorders that are associated with adverse early life events are often comorbid with psychiatric illnesses, suggesting a common underlying aetiology. Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder that is thought to involve a dysfunctional interaction between the brain and the gut. Essential aspects of the brain-gut axis include spinal pathways, the hypothalamic pituitary adrenal axis, the immune system, as well as the enteric microbiota. Accumulating evidence suggest that stress, especially in early life, is a predisposing factor to IBS.

OBJECTIVE

The objective of this review was to assess and compile the most relevant data on early life stress and alterations at all levels of the brain gut axis.

RESULTS

In this review, we describe the components of the brain-gut axis individually and how they are altered by maternal separation. The separated phenotype is characterised by alterations of the intestinal barrier function, altered balance in enteric microflora, exaggerated stress response and visceral hypersensitivity, which are all evident in IBS.

CONCLUSION

Thus, maternally separated animals are an excellent model of brain-gut axis dysfunction for the study of disorders such as IBS and for the development of novel therapeutic interventions.

Effects of intestinal mucosal blood flow and motility on intestinal mucosa

AIM: To investigate the role of intestinal mucosal blood flow (IMBF) and motility in the damage of intestinal mucosal barrier in rats with traumatic brain injury.

METHODS: Sixty-four healthy male Wistar rats were divided randomly into two groups: traumatic brain injury (TBI) group (n = 32), rats with traumatic brain injury; and control group (n = 32), rats with sham-operation. Each group was divided into four subgroups (n = 8) as 6, 12, 24 and 48 h after operation. Intestinal motility was measured by the propulsion ratio of a semi-solid colored marker (carbon-ink). IMBF was measured with the laser-Doppler technique. Endotoxin and D-xylose levels in plasma were measured to evaluate the change of intestinal mucosal barrier function following TBI.

RESULTS: The level of endotoxin was significantly higher in TBI group than in the control group at each time point (0.382 ± 0.014 EU/mL vs 0.102 ± 0.007 EU/mL, 0.466 ± 0.018 EU/mL vs 0.114 ± 0.021 EU/mL, 0.478 ± 0.029 EU/mL vs 0.112 ± 0.018 EU/mL and 0.412 ± 0.036 EU/mL vs 0.108 ± 0.011 EU/mL, P < 0.05). D-xylose concentrations in plasma in TBI group were significantly higher than in the control group (6.68 ± 2.37 mmol/L vs 3.66 ± 1.07 mmol/L, 8.51 ± 2.69 mmol /L vs 3.15 ± 0.95 mmol/L, 11.68 ± 3.24 mmol/L vs 3.78 ± 1.12 mmol/L and 10.23 ± 2.83 mmol/L vs 3.34 ± 1.23 mmol/ L, P < 0.05). The IMBF in TBI group was significantly lower than that in the control group (38.5 ± 2.8 PU vs 45.6 ± 4.6 PU, 25.2 ± 3.1 PU vs 48.2 ± 5.3 PU, 21.5 ± 2.7 PU vs 44.9 ± 2.8 PU, 29. 4 ± 3.8 PU vs 46.7 ± 3.2 PU) (P < 0.05). Significant decelerations of intestinal propulsion ratio in TBI groups were found compared with the control group (0.48% ± 0.06% vs 0.62% ± 0.03%, 0.37% ± 0.05% vs 0.64% ± 0.01%, 0.39% ± 0.07% vs 0.63% ± 0.05% and 0.46% ± 0.03% vs 0.65% ± 0.02%) (P < 0.05).

CONCLUSION: The intestinal mucosal permeability is increased obviously in TBI rats. Decrease of intestinal motility and IMBF occur early in TBI, both are important pathogenic factors for stress-related damage of the intestinal mucosal barrier in TBI.

Mast cell activation and autism

Autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by varying degrees of dysfunctional communication and social interactions, repetitive and stereotypic behaviors, as well as learning and sensory deficits. Despite the impressive rise in the prevalence of autism during the last two decades, there are few if any clues for its pathogenesis, early detection or treatment. Increasing evidence indicates high brain expression of pro-inflammatory cytokines and the presence of circulating antibodies against brain proteins. A number of papers, mostly based on parental reporting on their children's health problems, suggest that ASD children may present with "allergic-like" problems in the absence of elevated serum IgE and chronic urticaria. These findings suggest non-allergic mast cell activation, probably in response to environmental and stress triggers that could contribute to inflammation. In utero inflammation can lead to preterm labor and has itself been strongly associated with adverse neurodevelopmental outcomes. Premature babies have about four times higher risk of developing ASD and are also more vulnerable to infections, while delayed development of their gut-blood-brain barriers makes exposure to potential neurotoxins likely. Perinatal mast cell activation by infectious, stress-related, environmental or allergic triggers can lead to release of pro-inflammatory and neurotoxic molecules, thus contributing to brain inflammation and ASD pathogenesis, at least in a subgroup of ASD patients. This article is part of a Special Issue entitled: Mast cells in inflammation.

The enteric nervous system as a regulator of intestinal epithelial barrier function in health and disease

The intestinal epithelia proliferate and differentiate along the crypt villus axis to constitute a barrier cell layer separating some 10¹³ potentially harmful bacteria from a sterile mucosal compartment. Strict regulatory mechanisms are required to maintain a balance between the appropriate uptake of luminal food components and proteins, while constraining the exposure of the mucosal compartment to luminal antigens and microbes. The enteric nervous system is increasingly recognized as such a regulatory housekeeper of the epithelial barrier integrity, in addition to its ascribed immunomodulatory potential. Inflammation affects both epithelial integrity and barrier function and, in turn, loss of barrier function perpetuates inflammatory conditions. The observation that inflammatory conditions affect enteric neurons may add to the dysregulated barrier function in chronic disease. Here, we review the current understanding of the regulatory role of the nervous system in the maintenance of barrier function in healthy state, or during pathological conditions of, for instance, stress-induced colitis, surgical trauma or inflammation. We will discuss the clinical potential for advances in understanding the role of the enteric nervous system in this important phenomenon.

Partial hepatectomy, partial portal vein stenosis and mesenteric lymphadenectomy increase splanchnic mast cell infiltration in the rat

It is currently believed that portal hypertension induces an inflammatory response in which mast cells may be involved. The aim of this study was to verify the involvement of the intestinal submucosal and mesenteric lymph node mast cells in the splanchnic inflammatory response related to portal hypertension. Mast cell infiltration in the intestine (duodenum, jejunum, ileum, caecum and distal colon) and in the mesenteric lymph node complex (MLC) was measured using a stereological method in sham-operated rats (SO; n = 12), in two experimental models of portal hypertension, chronic (triple partial portal vein ligation, TPVL; n = 12) and transient (microsurgical partial hepatectomy; n = 12) and in rats in which the MLC was resected (n = 12). The small and large bowel submucosal infiltration increases in MLC-resected rats (p = 0.0001), in TPVL rats (p = 0.0001) and in rats with partial hepatectomy (p = 0.0001). An extensive mast cell infiltration in the MLC (p = 0.0001) was found in TPVL rats and in rats with partial hepatectomy (347.40+/-45.25 and 351.92+/-99.28/mm(3), respectively) in relation to sham-operated rats (135.27+/-30.28/mm(3)). We conclude that mast cells could be involved in the splanchnic alterations developed in the surgical experimental models of portal hypertension studied.

Peripheral and gastrointestinal immune systems of healthy cattle raised outdoors at pasture or indoors on a concentrate-based ration

Background

Despite an increasing preference of consumers for beef produced from more extensive pasture-based production systems and potential human health benefits from the consumption of such beef, data regarding the health status of animals raised on pasture are limited. The objective of this study was to characterise specific aspects of the bovine peripheral and the gastrointestinal muscosal immune systems of cattle raised on an outdoor pasture system in comparison to animals raised on a conventional intensive indoor concentrate-based system.

Results

A number of in vitro functional tests of immune cells suggested subtle differences between the animals on the outdoor versus indoor production systems. There was a decrease in the number of neutrophils and monocytes engaged in phagocytosis in outdoor cattle (P < 0.01 and P < 0.05, respectively) in comparison to those indoors. Following mitogen stimulation, a lower level of interferon-γ was produced in leukocytes from the outdoor animals (P < 0.05). There was evidence of a gastrointestinal nematode infection in the outdoor animals with elevated levels of serum pepsinogen (P < 0.001), a higher number of eosinophils (P < 0.05) and a higher level of interleukin-4 and stem cell factor mRNA expression (P < 0.05) in the outdoor animals in comparison to the indoor animals. Lower levels of copper and iodine were measured in the outdoor animals in comparison to indoor animals (P < 0.001).

Conclusion

Despite distinctly contrasting production systems, only subtle differences were identified in the peripheral immune parameters measured between cattle raised at pasture in comparison to animals raised on a conventional intensive indoor concentrate-based production system.

Early weaning stress impairs development of mucosal barrier function in the porcine intestine

Early life stress is a predisposing factor for the development of chronic intestinal disorders in adult life. Here, we show that stress associated with early weaning in pigs leads to impaired mucosal barrier function. Early weaning (15- to 21-day weaning age) resulted in sustained impairment in intestinal barrier function, as indicated by reductions in jejunal transepithelial electrical resistance and elevations in mucosal-to-serosal flux of paracellular probes [(3)H]mannitol and [(14)C]inulin measured at 5 and 9 wk of age, compared with that shown in late-weaned pigs (23- to 28-day weaning age). Elevated baseline short-circuit current was observed in jejunum from early-weaned pigs and was shown to be mediated via enhanced Cl(-) secretion. Jejunal barrier dysfunction in early-weaned pigs coincided with increased lamina propria immune cell density particularly mucosal mast cells. The mast cell stabilizer drug sodium cromoglycolate ameliorated barrier dysfunction and hypersecretion in early-weaned pigs, demonstrating an important role of mast cells. Furthermore, activation of mast cells ex vivo with c48/80 and corticotrophin-releasing factor (CRF) in pig jejunum mounted in Ussing chambers induced barrier dysfunction and elevations in short-circuit current that were inhibited with mast cell protease inhibitors. Experiments in which selective CRF receptor antagonists were administered to early-weaned pigs revealed that CRF receptor 1 (CRFr1) activation mediates barrier dysfunction and hypersecretion, whereas CRFr2 activation may be responsible for novel protective properties in the porcine intestine in response to early life stress.

Stress-related modulation of inflammation in experimental models of bowel disease and post-infectious irritable bowel syndrome: role of corticotropin-releasing factor receptors

The interaction between gut inflammatory processes and stress is gaining increasing recognition. Corticotropin-releasing factor (CRF)-receptor activation in the brain is well established as a key signaling pathway initiating the various components of the stress response including in the viscera. In addition, a local CRF signaling system has been recently established in the gut. This review summarize the present knowledge on mechanisms through which both brain and gut CRF receptors modulate intestinal inflammatory processes and its relevance towards increased inflammatory bowel disease (IBD) activity and post-infectious irritable bowel syndrome (IBS) susceptibility induced by stress.

The gut immune barrier and the blood-brain barrier: are they so different?

In order to protect itself from a diverse set of environmental pathogens and toxins, the body has developed a number of barrier mechanisms to limit the entry of potential hazards. Here, we compare two such barriers: the gut immune barrier, which is the primary barrier against pathogens and toxins ingested in food, and the blood-brain barrier, which protects the central nervous system from pathogens and toxins in the blood. Although each barrier provides defense in very different environments, there are many similarities in their mechanisms of action. In both cases, there is a physical barrier formed by a cellular layer that tightly regulates the movement of ions, molecules, and cells between two tissue spaces. These barrier cells interact with different cell types, which dynamically regulate their function, and with a different array of immune cells that survey the physical barrier and provide innate and adaptive immunity.