Effect of gut microbiota from Henoch-Schönlein Purpura patients on acid-sensitive ion channel 3 expression and intestinal motility in germ-free rats

Background It has been proven that gut microbiota alterations are involved in the development of Henoch-Schönlein Purpura (HSP). However, the pathogenesis of HSP hasn’t been eluciated. This study was to investigate the impact of gut microbiota from HSP on ASIC3 expression and interactions between microbiota and ASIC3 expression in the development of HSP. Methods Feces collected from HSP and healthy children at the First Affiliated Hospital of Anhui Medical University were made into fecal microbial solutions. Germ-free rats were randomly assigned to either the control or HSP groups. The HSP group of rats were administered the fecal microbiota solution of HSP children, while the control group rats were administered the fecal microbiota solution of healthy children. Abdominal withdrawal reflex (AWR) and intestinal propulsion rate of the rats were used to determine visceral sensitivity. Composition of the gut microbiota of HSP children was determined using 16S rRNA gene sequencing. ASIC3 expression in the colon was ascertained through qRT-PCR as well as western blotting analysis. Results The results showed a reduction in the number of species and abundance in the intestinal microbiota of children with HSP. Visceral sensitivity and intestinal propulsion rate of HSP group rats increased significantly, compared with the control group. Colon ASIC3 mRNA and protein levels in the HSP group were found to be upregulated. The microbiota dysbiosis of HSP patients could stimulate ASIC3 expression in the colon of Germ-free rats, which in turn affected intestinal motility. Conclusions These results suggested that HSP children had intestinal microbiota disorder, which might affect gut motility by down-regulating colon ASIC3 expression in rats.

Role of Enteric Glia as Bridging Element between Gut Inflammation and Visceral Pain Consolidation during Acute Colitis in Rats

Acute inflammation is particularly relevant in the pathogenesis of visceral hypersensitivity associated with inflammatory bowel diseases. Glia within the enteric nervous system, as well as within the central nervous system, contributes to neuroplasticity during inflammation, but whether enteric glia has the potential to modify visceral sensitivity following colitis is still unknown. This work aimed to investigate the occurrence of changes in the neuron–glial networks controlling visceral perception along the gut–brain axis during colitis, and to assess the effects of peripheral glial manipulation. Enteric glia activity was altered by the poison fluorocitrate (FC; 10 µmol kg−1 i.p.) before inducing colitis in animals (2,4-dinitrobenzenesulfonic acid, DNBS; 30 mg in 0.25 mL EtOH 50%), and visceral sensitivity, colon damage, and glia activation along the pain pathway were studied. FC injection significantly reduced the visceral hyperalgesia, the histological damage, and the immune activation caused by DNBS. Intestinal inflammation is associated with a parallel overexpression of TRPV1 and S100β along the gut–brain axis (colonic myenteric plexuses, dorsal root ganglion, and periaqueductal grey area). This effect was prevented by FC. Peripheral glia activity modulation emerges as a promising strategy for counteracting visceral pain induced by colitis.

Carbonic Anhydrase IV Selective Inhibitors Counteract the Development of Colitis-Associated Visceral Pain in Rats

Persistent pain affecting patients with inflammatory bowel diseases (IBDs) is still very difficult to treat. Carbonic anhydrase (CA) represents an intriguing pharmacological target considering the anti-hyperalgesic efficacy displayed by CA inhibitors in both inflammatory and neuropathic pain models. The aim of this work was to evaluate the effect of inhibiting CA IV, particularly when expressed in the gut, on visceral pain associated with colitis induced by 2,4-di-nitrobenzene sulfonic acid (DNBS) in rats. Visceral sensitivity was assessed by measuring animals’ abdominal responses to colorectal distension. Repeated treatment with the selective CA IV inhibitors AB-118 and NIK-67 effectively counteracted the development of visceral pain induced by DNBS. In addition to pain relief, AB-118 showed a protective effect against colon damage. By contrast, the anti-hyperalgesic activity of NIK-67 was independent of colon healing, suggesting a direct protective effect of NIK-67 on visceral sensitivity. The enzymatic activity and the expression of CA IV resulted significantly increased after DNBS injection. NIK-67 normalised CA IV activity in DNBS animals, while AB-118 was partially effective. None of these compounds influenced CA IV expression through the colon. Although further investigations are needed to study the underlying mechanisms, CA IV inhibitors are promising candidates in the search for therapies to relieve visceral pain in IBDs.

The role of visceral hypersensitivity in the pathogenesis of irritable bowel syndrome

This research includes visceral sensitivity and its mechanisms involved in the development of irritable bowel syndrome. Visceral hypersensitivity occupies the key place. The research has the description of etiological factors that form visceral hypersensitivity and also visceral sensitivity instrumental research methods, based on the use of the balloon dilation. The research also has the schemes of drug therapy for irritable bowel syndrome meanwhile the special attention is paid to the possible use of the sorbed probiotics and psychopharmacological drugs.

P495 The interplay of biopsychosocial factors and quality of life in Inflammatory Bowel Diseases: a network analysis

Background Quality of life (QoL) is one of the most relevant patient-reported outcomes in the treatment of patients with inflammatory bowel diseases (IBD), but does not only depend on disease activity. We aimed to investigate the interplay of biopsychosocial factors and their associations with QoL in patients IBD by using a network analytical approach (NA). Methods We measured QoL and anxiety, depression, illness identity, self-esteem, loneliness, childhood trauma, and visceral sensitivity with self-report questionnaires in two independent IBD-samples (sample 1: n=209, anonymous internet survey; sample 2: n=84, outpatients with active disease before the beginning of a biologic treatment). Additionally, fatigue, haemoglobin levels and response to biologic therapy (3–6 months after the first assessment) were assessed in sample 2. We estimated regularized partial correlation networks and conducted tests of accuracy and stability of the network parameters. Results In both samples, QoL had the strongest associations with visceral sensitivity and the illness identity dimension engulfment, a maladaptive integration of IBD into the ‘self’. QoL was uniquely associated with depressive symptoms and fatigue was an essential factor in this link (sample 2). Depression was the most central factor in the networks. Baseline depression scores were connected to response to biologic therapy in sample 2. Conclusion This is the first study using NA to assess the complex interplay between biopsychosocial factors and QoL in IBD. It reveals a comparable network structure in two independent samples emphasizing the importance of depression. Visceral sensitivity and engulfment connected most strongly to QoL. Beyond depression, visceral sensitivity and illness identity may be targetable characteristics to improve QoL in personalised holistic therapy in IBD.

Effect of gut microbiota from Henoch-Schönlein Purpura patients on acid-sensitive ion channel 3 expression and intestinal motility in Germ-free rats

Background It has been proven that intestinal microbiota alterations and acid-sensing ion channels are associated with the development of Henoch-Schönlein Purpura (HSP) and that the brain-gut axis, which involves the gut microbiota, plays important roles in many diseases. However, there have been no reports published on changes in ASIC3 expression caused by gut microbial composition and its impact on the development of HSP. This study was to investigate the impact of the intestinal microbiota in children with abdominal HSP on ASIC3 expression and interactions between the microbiota and ASIC3 expression on the development of HSP. Methods Feces collected from HSP children and healthy children at the First Affiliated Hospital of Anhui Medical University were made into fecal microbial solutions. Germ-free rats were randomly assigned to either the control or HSP groups. The HSP group of rats were administered the fecal microbiota solution of HSP children, while the control group rats were administered the fecal microbiota solution of healthy children. Abdominal withdrawal reflex (AWR) and intestinal propulsion rate of the rats were used to determine visceral sensitivity. Composition of the gut microbiota of HSP children was determined using 16S rRNA gene sequencing. ASIC3 expression in the dorsal root ganglion (DRG) was ascertained through real-time PCR as well as western blotting analysis. Results The results showed a reduction in the number of species and abundance in the intestinal microbiota of children with HSP. Visceral sensitivity and intestinal propulsion rate of HSP group rats increased significantly, compared with the control group. ASIC3 mRNA and protein levels in the DRG of the spinal cord of rats in the HSP group were found to be upregulated. Conclusions The microbiota dysbiosis of HSP patients could stimulate ASIC3 expression in the DRG of the spinal cord, which in turn affected intestinal motility. These results suggested that regulation of the brain-gut axis may show potential for the development of therapies that can prevent or treat HSP children, especially patients with severe gastrointestinal manifestations.

The role of gastrointestinal specific anxiety and alexithymia as predictors of the severity of irritable bowel syndrome in women

Aim. To analyze the role of gastrointestinal specific anxiety and alexithymia in predicting the severity of the disease in 194 women with moderate to severe IBS with refractory course (average duration of the disease 38.4 months). Methods of investigation. Gastrointestinal Symptom Rating Scale-IBS (GSRS-IBS), Irritable Bowel Syndrome Severity Scoring System (IBS-SSS), Visceral Sensitivity Index (VSI), TAS-20, HADS, and SF-12. Results. It was shown that in women, the severity of irritable bowel syndrome and the risks of refractory course are closely related to high alexithymia and uncontrolled gastrointestinal specific anxiety, which are also related to each other. Patients with severe IBS significantly differ from patients with moderate symptomocoplex manifestations (pain, bloating, diarrheal manifestations), satisfaction with the quality of life, pronounced symptoms of depression, visceral sensitivity and alexithymia, which contributes to the formation of a number of therapeutic barriers. Regression analysis showed that the severity of IBS was equally predicted by presence of alexithymia and gastrointestinal specific anxiety in the patient. Conclusions. Alexithymia, especially the difficulty of expressing negative emotions (for example, irritation, anger), describing feelings, desires to other people, was a stronger factor in women predicting the severity of IBS compared to gastrointestinal specific anxiety. The presented symptomatic picture of alexithymic manifestations in patients with IBS shows that violations of emotional awareness affect the pathogenesis, the spectrum of reinsurance and avoidance behavior.

A9 DORSAL ROOT GANGLIA NEURONAL RESPONSES AND SUBSTANCE P PRODUCTION ARE HIGHER IN MALE MICE

Background Abdominal pain is a common complaint in patients with chronic gastrointestinal disorders. Accumulating evidence suggests that gut microbiota is an important determinant of gut function, including visceral sensitivity. Germ-free (GF) mice have been shown to display visceral hypersensitivity, which normalizes after colonization. Sex also appears to play a key role in visceral sensitivity, as women report more abdominal pain than men. Thus, both gut bacteria and sex are important in the regulation of gut nociception, but the underlying mechanisms remain poorly understood. Aims To investigate the role of gut microbiota and sex in abdominal pain. Methods We used primary cultures of sensory neurons from dorsal root ganglia (DRG) of female and male conventionally raised (SPF) or germ-free (GF) mice (7–18 weeks old). To study the visceral afferent activity in vitro, calcium mobilization in DRG sensory neurons was measured by inverted fluorescence microscope using a fluorescent calcium probe Fluo-4 (1mM). Two parameters were considered i) the percentage of responding neurons ii) the intensity of the neuronal response. First, DRG sensory neurons were stimulated by a TRPV1 agonist capsaicin (12.5nM, 125nM and 1.25µM) or by a mixture of G-protein coupled receptors agonist (GPCR: bradykinin, histamine and serotonin; 1µM, 10µM and 100µM). We next measured the neuronal production of substance P and calcitonin gene-related peptide (CGRP), two neuropeptides associated with nociception, in response to capsaicin (1.25µM) or GPCR agonists (100µM) by ELISA and EIA, respectively. Results The percentage of neurons responding to capsaicin and GPCR agonists was similar in male and female SPF and GF mice. However, the intensity of the neuronal response was higher in SPF male compared to SPF female in response to capsaicin (125nM: p=0.0336; 1.25µM: p=0.033) but not to GPCR agonists. Neuronal activation was similar in GF and SPF mice of both sexes after administration of capsaicin or GPCR agonists. Furthermore, substance P and CGRP production by sensory neurons induced by capsaicin or GPCR agonists was similar in SPF and GF mice, regardless of sex. However, while the response to capsaicin was similar, the GPCR agonists-induced production of substance P was higher in SPF male mice compared to SPF females (p=0.003). The GPCR agonists-induced production of CGRP was similar in SPF male and female mice. Conclusions Our data suggest that at the level of DRG neurons, the absence of gut microbiota does not predispose to visceral hypersensitivity. The intensity of DRG neuronal responses to capsaicin and the GPCR agonists-induced production of substance P are higher in male compared to female mice, in contrast to previously published studies in various models of acute and chronic pain. Further studies are thus needed to investigate the role of sex in visceral sensitivity. Funding Agencies CIHR