scholarly journals The Nlrp6 inflammasome is not required for baseline colonic inner mucus layer formation or function

2019 ◽  
Vol 216 (11) ◽  
pp. 2602-2618 ◽  
Author(s):  
Joana K. Volk ◽  
Elisabeth E.L. Nyström ◽  
Sjoerd van der Post ◽  
Beatriz M. Abad ◽  
Bjoern O. Schroeder ◽  
...  
Keyword(s):  
Barrier Function ◽  
Independent Effect ◽  
Mucus Layer ◽  
Effect Analysis ◽  
Innate Immune Signaling ◽  
Inflammatory Bowel ◽  
And Function ◽  
Deficient Mice ◽  
Inflammasome Activity

The inner mucus layer (IML) is a critical barrier that protects the colonic epithelium from luminal threats and inflammatory bowel disease. Innate immune signaling is thought to regulate IML formation via goblet cell Nlrp6 inflammasome activity that controls secretion of the mucus structural component Muc2. We report that isolated colonic goblet cells express components of several inflammasomes; however, analysis of IML properties in multiple inflammasome-deficient mice, including littermate-controlled Nlrp6−/−, detect a functional IML barrier in all strains. Analysis of mice lacking inflammasome substrate cytokines identifies a defective IML in Il18−/− mice, but this phenotype is ultimately traced to a microbiota-driven, Il18-independent effect. Analysis of phenotypic transfer between IML-deficient and IML-intact mice finds that the Bacteroidales family S24-7 (Muribaculaceae) and genus Adlercrutzia consistently positively covary with IML barrier function. Together, our results demonstrate that baseline IML formation and function is independent of inflammasome activity and highlights the role of the microbiota in determining IML barrier function.

scholarly journals Irritable bowel syndrome: new insights into symptom mechanisms and advances in treatment

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 780 ◽  
Author(s):  
Robin Spiller
Keyword(s):  
Irritable Bowel Syndrome ◽  
New Agents ◽  
Enteric Nerves ◽  
Inflammatory Bowel ◽  
Magnetic Resonance Imaging Mri ◽  
Irritable Bowel ◽  
Fodmap Diet ◽  
And Function ◽  
The Impact

Despite being one of the most common conditions leading to gastroenterological referral, irritable bowel syndrome (IBS) is poorly understood. However, recent years have seen major advances. These include new understanding of the role of both inflammation and altered microbiota as well as the impact of dietary intolerances as illuminated by magnetic resonance imaging (MRI), which has thrown new light on IBS. This article will review new data on how excessive bile acid secretion mediates diarrhea and evidence from post infectious IBS which has shown how gut inflammation can alter gut microbiota and function. Studies of patients with inflammatory bowel disease (IBD) have also shown that even when inflammation is in remission, the altered enteric nerves and abnormal microbiota can generate IBS-like symptoms. The efficacy of the low FODMAP diet as a treatment for bloating, flatulence, and abdominal discomfort has been demonstrated by randomized controlled trials. MRI studies, which can quantify intestinal volumes, have provided new insights into how FODMAPs cause symptoms. This article will focus on these areas together with recent trials of new agents, which this author believes will alter clinical practice within the foreseeable future.

Establishing the role of PLVAP in protein-losing enteropathy: a homozygous missense variant leads to an attenuated phenotype

2018 ◽  
Vol 55 (11) ◽  
pp. 779-784 ◽  
Author(s):  
Alina Kurolap ◽  
Orly Eshach-Adiv ◽  
Claudia Gonzaga-Jauregui ◽  
Katya Dolnikov ◽  
Adi Mory ◽  
...  
Keyword(s):  
Barrier Function ◽  
Protein Function ◽  
Transmembrane Domain ◽  
Autosomal Recessive Inheritance ◽  
Missense Variant ◽  
Protein Loss ◽  
Protein Losing Enteropathy ◽  
Family Based ◽  
And Function

BackgroundIntestinal integrity is essential for proper nutrient absorption and tissue homeostasis, with damage leading to enteric protein loss, that is, protein-losing enteropathy (PLE). Recently, homozygous nonsense variants in the plasmalemma vesicle-associated protein gene (PLVAP) were reported in two patients with severe congenital PLE. PLVAP is the building block of endothelial cell (EC) fenestral diaphragms; its importance in barrier function is supported by mouse models of Plvap deficiency.ObjectiveTo genetically diagnose two first-degree cousins once removed, who presented with PLE at ages 22 and 2.5 years.MethodsFamily-based whole exome sequencing was performed based on an autosomal recessive inheritance model. In silico analyses were used to predict variant impact on protein structure and function.ResultsWe identified a rare homozygous variant (NM_031310.2:c.101T>C;p.Leu34Pro) in PLVAP, which co-segregated with the disease. Leu34 is predicted to be located in a highly conserved, hydrophobic, α-helical region within the protein’s transmembrane domain, suggesting Leu34Pro is likely to disrupt protein function and/or structure. Electron microscopy and PLVAP immunohistochemistry demonstrated apparently normal diaphragm morphology, predicted to be functionally affected.ConclusionsBiallelic missense variants in PLVAP can cause an attenuated form of the PLE and hypertriglyceridaemia syndrome. Our findings support the role of PLVAP in the pathophysiology of PLE, expand the phenotypic and mutation spectrums and underscore PLVAP’s importance in EC barrier function in the gut.

scholarly journals Nemo-Like Kinase in Development and Diseases: Insights from Mouse Studies

2020 ◽  
Vol 21 (23) ◽  
pp. 9203
Author(s):  
Renée Daams ◽  
Ramin Massoumi
Keyword(s):  
Tissue Homeostasis ◽  
Spinocerebellar Ataxias ◽  
Adult Tissue ◽  
Signalling Molecules ◽  
Cellular Processes ◽  
Protein Map ◽  
Mitogen Activated Protein ◽  
And Function ◽  
Deficient Mice

The Wnt signalling pathway is a central communication cascade between cells to orchestrate polarity and fate during development and adult tissue homeostasis in various organisms. This pathway can be regulated by different signalling molecules in several steps. One of the coordinators in this pathway is Nemo-like kinase (NLK), which is an atypical proline-directed serine/threonine mitogen-activated protein (MAP) kinase. Very recently, NLK was established as an essential regulator in different cellular processes and abnormal NLK expression was highlighted to affect the development and progression of various diseases. In this review, we focused on the recent discoveries by using NLK-deficient mice, which show a phenotype in the development and function of organs such as the lung, heart and skeleton. Furthermore, NLK could conduct the function and differentiation of cells from the immune system, in addition to regulating neurodegenerative diseases, such as Huntington’s disease and spinocerebellar ataxias. Overall, generations of NLK-deficient mice have taught us valuable lessons about the role of this kinase in certain diseases and development.

scholarly journals Aberrant Contraction of Antigen-Specific CD4 T Cells after Infection in the Absence of Gamma Interferon or Its Receptor

2006 ◽  
Vol 74 (11) ◽  
pp. 6252-6263 ◽  
Author(s):  
Jodie S. Haring ◽  
John T. Harty
Keyword(s):  
T Cells ◽  
Cd4 T Cells ◽  
Interleukin 2 ◽  
Gamma Interferon ◽  
Model Systems ◽  
Important Regulator ◽  
Ifn Γ ◽  
And Function ◽  
Deficient Mice

ABSTRACT Several lines of evidence from different model systems suggest that gamma interferon (IFN-γ) is an important regulator of T-cell contraction after antigen (Ag)-driven expansion. To specifically investigate the role of IFN-γ in regulating the contraction of Ag-specific CD4 T cells, we infected IFN-γ−/− and IFN-γR1−/− mice with attenuated Listeria monocytogenes and monitored the numbers of Ag-specific CD4 T cells during the expansion, contraction, and memory phases of the immune response to infection. In the absence of IFN-γ or the ligand-binding portion of its receptor, Ag-specific CD4 T cells exhibited normal expansion in numbers, but in both strains of deficient mice there was very little decrease in the number of Ag-specific CD4 T cells even at time points later than day 90 after infection. This significant delay in contraction was not due to prolonged infection, since mice treated with antibiotics to conclusively eliminate infection exhibited the same defect in contraction. In addition to altering the number of Ag-specific CD4 T cells, the absence of IFN-γ signaling also changed the phenotype of cells generated after infection. IFN-γR1−/− Ag-specific CD4 T cells reacquired expression of CD127 more quickly than wild-type cells, and more IFN-γR1−/− CD4 T cells were capable of producing both IFN-γ and interleukin 2 following Ag stimulation. From these data we conclude that IFN-γ regulates the contraction, phenotype, and function of Ag-specific CD4 T cells generated after infection.

Mast Cell Tryptase Promotes Inflammatory Bowel Disease–Induced Intestinal Fibrosis

2020 ◽  
Author(s):  
Bin Liu ◽  
Mu-Qing Yang ◽  
Tian-Yu Yu ◽  
Yang-Yang Yin ◽  
Ying Liu ◽  
...  
Keyword(s):  
Inflammatory Bowel Disease ◽  
Human Colon ◽  
Underlying Mechanism ◽  
Control Group ◽  
Wild Type ◽  
Intestinal Fibrosis ◽  
Ecm Proteins ◽  
Inflammatory Bowel ◽  
Deficient Mice

Abstract Background Intestinal fibrosis is the final pathological outcome of chronic intestinal inflammation without specific therapeutic drugs, which leads to ileus and surgical intervention. Intestinal fibrosis is characterized by excessive deposition of extracellular matrix (ECM). The role of mast cells (MCs), which are members of the sentinel immune cell population, is unknown in intestinal fibrosis. Methods In this study, we analyzed changes in MCs, tryptase proteins, and ECM components in human fibrotic and control patient intestines. We constructed dextran sodium sulfate–induced intestinal fibrosis models using wild-type mice, MC-reconstituted mice, and MC-deficient mice to explore the role of MCs and tryptase in intestinal fibrosis. The roles and mechanisms of MCs and tryptase on fibroblasts were evaluated using human MCs (HMC-1 and LAD-2), commercial tryptase proteins, human colon fibroblasts (CCD-18Co fibroblasts), the tryptase inhibitor APC366, and the protease-activated receptor-2 (PAR-2) antagonist ENMD-1068. Results Regardless of whether the colon was a human colon or a mouse colon, the fibrotic intestinal tissue had increased MC infiltration and a higher expression of ECM proteins or genes than that of the control group. The dextran sodium sulfate–induced intestinal fibrosis in MC-deficient mice was alleviated compared with that in wild-type mice. After MC reconstruction in MC-deficient mice, the alleviating effect disappeared. Tryptase, as a content stored in MC granules, was released into fibrotic intestinal tissues in the form of degranulation, resulting in an increased expression of tryptase. Compared with the control group, the tryptase inhibition group (the APC366 group) had reduced intestinal fibrosis. The CCD-18Co fibroblasts, when cocultured with MCs or treated with tryptase proteins, were activated to differentiate into myofibroblasts and secrete more ECM proteins (such as collagen and fibronectin). The underlying mechanism of fibroblast activation by tryptase was the activation of the PAR-2/Akt/mTOR pathway. Conclusions We found that MC tryptase promotes inflammatory bowel disease–induced intestinal fibrosis. The underlying mechanism is that tryptase promotes the differentiation of fibroblasts into fibrotic-phenotype myofibroblasts by activating the PAR-2/Akt/ mTOR pathway of fibroblasts.

MiR-223 is dispensable for platelet production and function in mice

2013 ◽  
Vol 110 (12) ◽  
pp. 1207-1214 ◽  
Author(s):  
Xavier Loyer ◽  
Simon Leierseder ◽  
Tobias Petzold ◽  
Lin Zhang ◽  
Steffen Massberg ◽  
...  
Keyword(s):  
Platelet Adhesion ◽  
Cell Types ◽  
Surface Expression ◽  
Wild Type ◽  
Platelet Production ◽  
Multiple Cell ◽  
And Function ◽  
Deficient Mice ◽  
Platelet Depletion

SummaryMicroRNAs (miRNAs) are key physiological regulators in multiple cell types. Here, we assessed platelet production and function in mice deficient in miR-223, one of the most abundantly expressed miRNAs in platelets and megakaryocytes. We found platelet number, size, lifespan as well as surface expression of platelet adhesion receptors to be unchanged in miR-223-deficient mice. Likewise, loss of miR-223 did not affect platelet activation, adhesion and aggregation and also had no effect on bleeding times. Moreover, miR-223 null megakaryocytes developed normally and were capable to form pro-platelets. However, we detected a transient delay in the recovery of platelet numbers following antibody-induced platelet depletion in miR-223-deficient animals. This delay was not observed after transplantation of bone marrow from miR-223-deficient animals into wild-type recipients, indicating a non-cell-autonomous role of miR-223 for thrombopoiesis. Overall, our data indicate a surprisingly modest role of miR-223 in platelet production, while the function of platelets does not seem to depend on miR-223.

Critical role of class IA PI3K for c-Rel expression in B lymphocytes

Blood ◽  
2009 ◽  
Vol 113 (5) ◽  
pp. 1037-1044 ◽  
Author(s):  
Satoshi Matsuda ◽  
Yohei Mikami ◽  
Masashi Ohtani ◽  
Mari Fujiwara ◽  
Yasuko Hirata ◽  
...  
Keyword(s):  
B Cell ◽  
Critical Role ◽  
Cell Development ◽  
B Cell Development ◽  
Transcription Factor Family ◽  
Cell Functions ◽  
Pi3k Activity ◽  
And Function ◽  
Deficient Mice

AbstractThe fact that the Xid mutation of Btk impairs the ability of pleckstrin homo-logy domain of Btk to bind phosphatidylinositol-(3,4,5)-trisphosphate, a product of class IA phosphoinositide-3 kinases (PI3Ks), has been considered strong evidence for the hypothesis that Btk functions downstream of PI3Ks. We demonstrate here that the Xid mutation renders the Btk protein unstable. Furthermore, class IA PI3K- and Btk-deficient mice show different phenotypes in B-cell development, collectively indicating that PI3Ks and Btk differentially function in BCR signal transduction. Nevertheless, both PI3K and Btk are required for the activation of NF-κB, a critical transcription factor family for B-cell development and function. We demonstrate that PI3Ks maintain the expression of NF-κB proteins, whereas Btk is known to be essential for IκB degradation and the translocation of NF-κB to the nucleus. The loss of PI3K activity results in marked reduction of c-Rel and to a lesser extent RelA expression. The lentivirus-mediated introduction of c-Rel corrects both developmental and proliferative defects in response to BCR stimulation in class IA PI3K-deficient B cells. These results show that the PI3K-mediated control of c-Rel expression is essential for B-cell functions.

scholarly journals Bile Acids and Microbiota: Multifaceted and Versatile Regulators of the Liver–Gut Axis

2021 ◽  
Vol 22 (3) ◽  
pp. 1397
Author(s):  
Niklas Grüner ◽  
Jochen Mattner
Keyword(s):  
Bile Acids ◽  
Current Knowledge ◽  
Gut Bacteria ◽  
Intestinal Lumen ◽  
Clostridioides Difficile ◽  
Physiological Processes ◽  
Local Site ◽  
Inflammatory Bowel ◽  
And Function

After their synthesis from cholesterol in hepatic tissues, bile acids (BAs) are secreted into the intestinal lumen. Most BAs are subsequently re-absorbed in the terminal ileum and are transported back for recycling to the liver. Some of them, however, reach the colon and change their physicochemical properties upon modification by gut bacteria, and vice versa, BAs also shape the composition and function of the intestinal microbiota. This mutual interplay of both BAs and gut microbiota regulates many physiological processes, including the lipid, carbohydrate and energy metabolism of the host. Emerging evidence also implies an important role of this enterohepatic BA circuit in shaping mucosal colonization resistance as well as local and distant immune responses, tissue physiology and carcinogenesis. Subsequently, disrupted interactions of gut bacteria and BAs are associated with many disorders as diverse as Clostridioides difficile or Salmonella Typhimurium infection, inflammatory bowel disease, type 1 diabetes, asthma, metabolic syndrome, obesity, Parkinson’s disease, schizophrenia and epilepsy. As we cannot address all of these interesting underlying pathophysiologic mechanisms here, we summarize the current knowledge about the physiologic and pathogenic interplay of local site microbiota and the enterohepatic BA metabolism using a few selected examples of liver and gut diseases.

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