Gut fungi in irritable bowel syndrome: A painful recognition

This thesis focused on the role of fungi in the irritable bowel syndrome (IBS). IBS is a common, stress related, functional gastrointestinal disorder, characterized by chronic abdominal pain. A part of IBS patients show increased perception of pain to a rectal stimulus compared to healthy subjects. This so called hypersensitivity of the viscera is thought to represent a pathological mechanism behind the abdominal pain characteristic for IBS. The relevance of fungi was studied in the pre-clinical rat maternal separation model. In this model, rat pups are predisposed by maternal separation, and subjection to acute stress at adult age triggers, similar to IBS patients, hypersensitivity of the viscera. We observed that treatment with antifungals prevented the development of post stress visceral hypersensitivity. Remarkably, this hypersensitive phenotype in IBS model rats was accompanied by a specific fungal signature. Probably the development visceral hypersensitivity involves the recognition of fungal cell wall β-glucans by Dectine-1, a pathogen recognition receptor expressed on mast cells. After Dectine-1 activation, mast cells respond by the release of histamine which ultimately results in sensitization of afferent neurons. There is no current treatment for abdominal pain in IBS. Our research has identified a completely novel mechanism by which IBS develops and might thus lead to novel therapies

Gut fungi in irritable bowel syndrome:A painful recognition

This thesis focused on the role of fungi in the irritable bowel syndrome (IBS). IBS is a common, stress related, functional gastrointestinal disorder, characterized by chronic abdominal pain. A part of IBS patients show increased perception of pain to a rectal stimulus compared to healthy subjects. This so called hypersensitivity of the viscera is thought to represent a pathological mechanism behind the abdominal pain characteristic for IBS. The relevance of fungi was studied in the pre-clinical rat maternal separation model. In this model, rat pups are predisposed by maternal separation, and subjection to acute stress at adult age triggers, similar to IBS patients, hypersensitivity of the viscera. We observed that treatment with antifungals prevented the development of post stress visceral hypersensitivity. Remarkably, this hypersensitive phenotype in IBS model rats was accompanied by a specific fungal signature. Probably the development visceral hypersensitivity involves the recognition of fungal cell wall β-glucans by Dectine-1, a pathogen recognition receptor expressed on mast cells. After Dectine-1 activation, mast cells respond by the release of histamine which ultimately results in sensitization of afferent neurons. There is no current treatment for abdominal pain in IBS. Our research has identified a completely novel mechanism by which IBS develops and might thus lead to novel therapies

Painful interactions: Microbial compounds and visceral pain

Visceral pain, characterized by abdominal discomfort, originates from organs in the abdominal cavity and is a characteristic symptom in patients suffering from irritable bowel syndrome, vulvodynia or interstitial cystitis. Most organs in which visceral pain originates are in contact with the external milieu and continuously exposed to microbes. In order to maintain homeostasis and prevent infections, the immune- and nervous system in these organs cooperate to sense and eliminate (harmful) microbes. Recognition of microbial components or products by receptors expressed on cells from the immune and nervous system can activate immune responses but may also cause pain. We review the microbial compounds and their receptors that could be involved in visceral pain development

A novel, high stringency selection system allows screening of few clones for high protein expression.

To obtain highly productive mammalian cell lines, often large numbers of clones need to be screened. This is largely due to low selection stringencies, creating many, but low protein producing clones. To remedy this problem, a novel, very stringent selection system was designed, to create few, but high protein producing clones. In essence, a selection marker with a startcodon that confers attenuated translation initiation frequency was placed upstream of the gene of interest with a startcodon that confers optimal translation initiation. From the transcribed bicistronic mRNA, the selection marker is translated at a low frequency, and the protein of interest at a high frequency. This selection system is so stringent that clones form only rarely. However, application of anti-repressor elements, which increase promoter activity, did induce the formation of clones that expressed proteins at high levels. When combined with anti-repressor elements, this novel selection system can be a valuable tool to rapidly create few, but highly productive mammalian cell lines

Reversal of visceral hypersensitivity in rat by Menthacarin , a proprietary combination of essential oils from peppermint and caraway, coincides with mycobiome modulation

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder associated with altered gastrointestinal microflora and increased nociception to colonic distension. This visceral hypersensitivity can be reversed in our rat maternal separation model by fungicides. Menthacarin is a proprietary combination of essential oils from Mentha x piperita L. and Carum carvi. Because these oils exhibit antifungal and antibacterial properties, we investigated whether Menthacarin can reverse existing visceral hypersensitivity in maternally separated rats. In non-handled and maternally separated rats, we used the visceromotor responses to colorectal distension as measure for visceral sensitivity. We evaluated this response before and 24 hours after water-avoidance stress and after 7 days treatment with Menthacarin or control. The pre- and post-treatment mycobiome and microbiome were characterized by sequencing of fungal internal transcribed spacer 1 (ITS-1) and bacterial 16s rDNA regions. In vitro antifungal and antimicrobial properties of Menthacarin were studied with radial diffusion assay. Menthacarin inhibited in vitro growth of yeast and bacteria. Water-avoidance caused visceral hypersensitivity in maternally separated rats, and this was reversed by treatment. Multivariate analyses of ITS-1 and 16S high throughput data showed that maternal separation, induced changes in the myco- and microbiome. Menthacarin treatment of non-handled and maternally separated rats shifted the mycobiomes to more similar compositions. The development of visceral hypersensitivity in maternally separated rats and the Menthacarin -mediated reversal of hypersensitivity is associated with changes in the mycobiome. Therefore, Menthacarin may be a safe and effective treatment option that should be tested for IB

Reversal of visceral hypersensitivity in rat by Menthacarin , a proprietary combination of essential oils from peppermint and caraway, coincides with mycobiome modulation

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder associated with altered gastrointestinal microflora and increased nociception to colonic distension. This visceral hypersensitivity can be reversed in our rat maternal separation model by fungicides. Menthacarin is a proprietary combination of essential oils from Mentha x piperita L. and Carum carvi. Because these oils exhibit antifungal and antibacterial properties, we investigated whether Menthacarin can reverse existing visceral hypersensitivity in maternally separated rats. In non-handled and maternally separated rats, we used the visceromotor responses to colorectal distension as measure for visceral sensitivity. We evaluated this response before and 24 hours after water-avoidance stress and after 7 days treatment with Menthacarin or control. The pre- and post-treatment mycobiome and microbiome were characterized by sequencing of fungal internal transcribed spacer 1 (ITS-1) and bacterial 16s rDNA regions. In vitro antifungal and antimicrobial properties of Menthacarin were studied with radial diffusion assay. Menthacarin inhibited in vitro growth of yeast and bacteria. Water-avoidance caused visceral hypersensitivity in maternally separated rats, and this was reversed by treatment. Multivariate analyses of ITS-1 and 16S high throughput data showed that maternal separation, induced changes in the myco- and microbiome. Menthacarin treatment of non-handled and maternally separated rats shifted the mycobiomes to more similar compositions. The development of visceral hypersensitivity in maternally separated rats and the Menthacarin -mediated reversal of hypersensitivity is associated with changes in the mycobiome. Therefore, Menthacarin may be a safe and effective treatment option that should be tested for IB