| 1. |
- Berglund, Martin, 1979, et al.
(author)
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Gender dependent importance of IRAK-1 in dextran sulfate sodium induced colitis
- 2009
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In: Cellular Immunology. - : Elsevier BV. - 1090-2163 .- 0008-8749. ; 259:1, s. 27-32
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Journal article (peer-reviewed)abstract
- Toll-like receptor (TLR) signaling is important for the induction of pro-inflammatory cytokines and interferon (IFN)-inducible genes in response to bacterial and viral challenge. Interleukin-1 receptor-associated kinase-1 (IRAK-1) is a signaling kinase situated downstream of the adapter protein myeloid differentiation factor 88 (MyD88) in the TLR intracellular signaling cascade and is required for normal signal transduction through this pathway. We investigated the importance of IRAK-1 in intestinal inflammation by using the dextran sulfate sodium (DSS)-colitis model. We show that IRAK-1 deficient mice are protected against systemic signs of inflammation, i.e., weight loss and spleen enlargement compared to wild-type controls irrespective of gender. However, IRAK-1(-/y) males but not IRAK-1(-/-) females display significant protection against colitis and thymic atrophy compared to wild-type mice. Our results indicate a gender specific effect of IRAK-1 in the DSS-induced colitis, an interesting finding since the Irak-1 gene is located on the X-chromosome and several inflammatory diseases have a gender dependent incidence.
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| 2. |
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| 3. |
- Berglund, Martin, et al.
(author)
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IL-1 receptor-associated kinase M downregulates DSS-induced colitis
- 2010
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In: Inflammatory Bowel Diseases. - : Oxford University Press (OUP). - 1078-0998 .- 1536-4844. ; 16:10, s. 1778-1786
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Journal article (peer-reviewed)abstract
- Background: Ulcerative colitis is associated with increased colon permeability resulting in bacterial translocation into the lamina propria. We investigate the importance of the Toll-like receptor (TLR) regulating protein IL-1 receptor-associated kinase M (IRAK-M) using the erosive dextran sulfate sodium (DSS)-induced model of colitis. Methods: IRAK-M-competent and -incompetent mice were treated with 3% DSS for 5 days followed by 2 days of regular drinking water. Clinical signs of disease were followed for 7 days. At day 7 the mice were sacrificed and plasma and tissue were collected for histopathological examination and analyses of the production of cytokines and chemokines as well as expression of T-cell transcription factors. Results: At day 7 IRAK-M-deficient mice display a reduced total body weight (77.1 +/- 2.1 versus 88.5 +/- 2.0, *P=0.002) and an increased macroscopical (2.7 +/- 0.2 versus 1.6 +/- 0.1, *P 0.002) and histopathological (6.0 +/- 0 versus 3.3 +/- 60.5, *P < 0.001) colon score compared to wildtype mice. Furthermore, IRAK-M-deficient mice have increased colon mRNA expression of proinflammatory cytokines and increased tumor necrosis factor concentrations (41.1 +/- 13.5 versus 12.8 +/- 2.0 pg/mL, *P = 0.010) in plasma. Conclusions: This is the first report examining the role of IRAK-M in colitis. We find that IRAK-M is of critical importance in downregulating induction and progression of DSS colitis, and thereby suggesting that IRAK-M might be a target for future interventional therapies. (Inflamm Bowel Dis 2010; 16: 1778-1786)
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| 4. |
- Bitar, Aziz, et al.
(author)
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Induction of immunomodulatory miR-146a and miR-155 in small intestinal epithelium of Vibrio cholerae infected patients at acute stage of cholera
- 2017
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 12:3
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Journal article (peer-reviewed)abstract
- The potential immunomodulatory role of microRNAs in small intestine of patients with acute watery diarrhea caused by Vibrio cholerae O1 or enterotoxigenic Escherichia coli (ETEC) infection was investigated. Duodenal biopsies were obtained from study-participants at the acute (day 2) and convalescent (day 21) stages of disease, and from healthy individuals. Levels of miR-146a, miR-155 and miR-375 and target gene (IRAK1, TRAF6, CARD10) and 11 cytokine mRNAs were determined by qRT-PCR. The cellular source of microRNAs in biopsies was analyzed by in situ hybridization. The ability of V. cholerae bacteria and their secreted products to cause changes in microRNA- and mRNA levels in polarized tight monolayers of intestinal epithelial cells was investigated. miR-146a and miR-155 were expressed at significantly elevated levels at acute stage of V. cholerae infection and declined to normal at convalescent stage (P<0.009 versus controls; P = 0.03 versus convalescent stage, pairwise). Both microRNAs were mainly expressed in the epithelium. Only marginal down-regulation of target genes IRAK1 and CARD10 was seen and a weak cytokine-profile was identified in the acute infected mucosa. No elevation of microRNA levels was seen in ETEC infection. Challenge of tight monolayers with the wild type V. cholerae O1 strain C6706 and clinical isolates from two study-participants, caused significant increase in miR-155 and miR-146a by the strain C6706 (P<0.01). One clinical isolate caused reduction in IRAK1 levels (P<0.05) and none of the strains induced inflammatory cytokines. In contrast, secreted factors from these strains caused markedly increased levels of IL-8, IL-1β, and CARD10 (P<0.001), without inducing microRNA expression. Thus, miR-146a and miR-155 are expressed in the duodenal epithelium at the acute stage of cholera. The inducer is probably the V. cholerae bacterium. By inducing microRNAs the bacterium can limit the innate immune response of the host, including inflammation evoked by its own secreted factors, thereby decreasing the risk of being eliminated.
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| 5. |
- Flood, Peter, et al.
(author)
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DNA sensor-associated type I interferon signaling is increased in ulcerative colitis and induces JAK-dependent inflammatory cell death in colonic organoids
- 2022
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In: American Journal of Physiology - Gastrointestinal and Liver Physiology. - : American Physiological Society. - 0193-1857 .- 1522-1547. ; 323:5, s. G439-G460
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Journal article (peer-reviewed)abstract
- DNA sensor pathways can initiate inflammasome, cell death, and type I interferon (IFN) signaling in immune-mediated inflammatory diseases (IMIDs), including type I interferonopathies. We investigated the involvement of these pathways in the pathogenesis of ulcerative colitis (UC) by analyzing the expression of DNA sensor, inflammasome, and type I IFN biomarker genes in colonic mucosal biopsy tissue from control (n = 31), inactive UC (n = 31), active UC (n = 33), and a UC single-cell RNA-Seq dataset. The effects of type I IFN (IFN-β), IFN-γ, and TNF-α on gene expression, cytokine production, and cell death were investigated in human colonic organoids. In organoids treated with cytokines alone, or in combination with NLR family pyrin domain-containing 3 (NLRP3), caspase, or JAK inhibitors, cell death was measured, and supernatants were assayed for IL-1β/IL-18/CXCL10. The expression of DNA sensor pathway genes-PYHIN family members [absent in melanoma 2 (AIM2), IFI16, myeloid cell nuclear differentiation antigen (MNDA), and pyrin and HIN domain family member 1 (PYHIN1)- as well as Z-DNA-binding protein 1 (ZBP1), cyclic GMP-AMP synthase (cGAS), and DDX41 was increased in active UC and expressed in a cell type-restricted pattern. Inflammasome genes (CASP1, IL1B, and IL18), type I IFN inducers [stimulator of interferon response cGAMP interactor 1 (STING), TBK1, and IRF3), IFNB1, and type I IFN biomarker genes (OAS2, IFIT2, and MX2) were also increased in active UC. Cotreatment of organoids with IFN-β or IFN-γ in combination with TNFα increased expression of IFI16, ZBP1, CASP1, cGAS, and STING induced cell death and IL-1β/IL-18 secretion. This inflammatory cell death was blocked by the JAK inhibitor tofacitinib but not by inflammasome or caspase inhibitors. Increased type I IFN activity may drive elevated expression of DNA sensor genes and JAK-dependent but inflammasome-independent inflammatory cell death of colonic epithelial cells in UC.NEW & NOTEWORTHY This study found that patients with active UC have significantly increased colonic gene expression of cytosolic DNA sensor, inflammasome, STING, and type I IFN signaling pathways. The type I IFN, IFN-β, in combination with TNF-α induced JAK-dependent but NLRP3 and inflammasome-independent inflammatory cell death of colonic organoids. This novel inflammatory cell death phenotype is relevant to UC immunopathology and may partially explain the efficacy of the JAKinibs tofacitinib and upadacitinib in patients with UC.
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| 6. |
- Fredin, Maria Fritsch, 1970, et al.
(author)
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Predicting and monitoring colitis development in mice by micro-computed tomography
- 2008
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In: Inflammatory Bowel Diseases. - : Oxford University Press (OUP). - 1078-0998 .- 1536-4844. ; 14:4, s. 491-499
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Journal article (peer-reviewed)abstract
- BACKGROUND: Computed tomography (CT) has been developed as a tool for monitoring human inflammatory bowel disease (IBD). The aim of this study was to evaluate colon wall thickness as a noninvasive marker in the dextran sodium sulfate (DSS) mouse model of colitis using micro-CT. METHODS: Mice were examined by micro-CT 1, 2, or 4 times between day 0 (d0) and d26 after induction of colitis to document the kinetics of changes in colon wall thickness and its relation to colitis development. RESULTS: DSS-treated mice displayed a significantly thicker colon wall at all timepoints (days 5, 8, 12, 19, and 26) investigated compared to healthy controls. Colon wall thickness showed a good correlation to the macroscopic grading of colitis (r = 0.81). The increase in colon wall thickness occurred mainly during the acute phase of colitis (between days 5 and 12) and did not progress much further in the chronic phase of colitis (d26). Colon wall thickness at d26 was thereby predicted by measurements at d12. All mice did not respond equally to DSS and this difference was manifest during the first 2 weeks of colitis, providing an important tool in stratifying responders from nonresponders. CONCLUSIONS: While the potential impact of handling and anesthesia should be considered on repeated micro-CT, irradiation exposure during repeated micro-CT did not affect the development of colitis. Thus, the results suggest that micro-CT can be used for monitoring and prediction of the inflammatory response in mouse colitis in future therapeutic studies.
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| 7. |
- Fredin, Maria Fritsch, 1970, et al.
(author)
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The application and relevance of ex vivo culture systems for assessment of IBD treatment in murine models of colitis
- 2008
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In: Pharmacological Research. - : Elsevier BV. - 1043-6618 .- 1096-1186. ; 58:3-4, s. 222-231
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Journal article (peer-reviewed)abstract
- The aim of this study was to investigate the relevance of mouse ex vivo cultures as a first screening model for new therapeutic agents of Inflammatory Bowel Disease (IBD). Two murine models (dextran sodium sulphate (DSS)-induced colitis and Gαi2-deficient mice) and two anti-inflammatory agents (methyl-prednisolone and the proteasome inhibitor MG132) were evaluated. The in vivo effects of methyl-prednisolone were assessed in both models. Ex vivo colonic tissue from both mouse models were cultured in the presence or absence of the drugs and TaqMan Low-Density arrays were used to assess the regulation of inflammatory genes before and after drug treatment. Colitis induced a similar inflammatory gene profile in both mouse models in in vivo studies and in ex vivo cultures. The differences encountered reflected the different phases of colitis in the models, e.g. innate cytokine/chemokine profile in the DSS model and T cell related markers in Gαi2-deficient mice. After steroid treatment, a similar pattern of genes was suppressed in the two mouse models. We confirmed the suppression of inflammatory gene expression for IL-1β, IL-6 and iNOS in ex vivo and in vivo colons from both mouse models by quantitative RT-PCR. Importantly, the inflammatory responses in the murine ex vivo culture system reflected the in vivo response in the inflamed colonic tissue as assessed by changes in inflammatory gene expression, suggesting that the murine culture system can be used for validation of future IBD therapies.
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| 8. |
- Melgar, Silvia
(author)
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Human intestinal T lymphocytes : a comparative analysis of phenotype and function in normal and inflamed mucosa
- 2002
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Doctoral thesis (other academic/artistic)abstract
- The epithelial lining of the gut must allow immediate contact with beneficial components as nutrients and normal microflora. At the same time it runs the constant risk of attack from pathogenic microbes and noxious agents. Only a singel layer of epithelial cells separates the body's largest lymphocyte population from foreign components in the gut lumen. I have addressed two fundamental questions: 1) How does the immune system in the gut specifically protect against infectious agents and other harmful substances and at the same time avoid overreaction against antigens in food and commensals? and 2) What causes the immune protection breakdown in inflammatory bowel disease? To this end, the phenotype, distribution and functions of T lymphocytes, key players in adaptive immunity, were compared to T lymphocytes in the chronically inflamed intestine of patients with ulcerative colitis (UC) and Crohn's disease (CD). Intestinal T lymphocytes are present both within the epithelium, intraepithelial lymphocytes (IEL), and in the underlying lamina propria (LP). Even though there are many T lymphocytes in normal intestine, there is a highly significant increase in inflamed intestine. They seem to be involved in the pathogenesis of both UC and CD. In UC, T lymphocytes populate the basal lymphoid aggregates, which occupy up to 45% of LP.Phenotype was analysed in situ by immunomorphometry and immunoelecton microscopy, and by immunoflow cytometry of isolated IEL and lamina propria lymphocytes (LPL). Cytokine production was monitored as the frequencies of cells expressing the proteins in situ and as mRNA expression in purified T lymphocytes using quantitative RT-PCR. Cytotoxicity was measured in functional assays using purified IEL and LPL as effector cells and as expression of cytotoxic effector molecules. The responsiveness to polyclonal T cell activators was assayed as proliferation and secretion of cytokines in vitro.Major findings were: (1) Interleukin-2 (IL-2), the Th1 cytokines interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α), the down-regulatory cytokine transforming growth factor-β1 (TGF-β1) and the chemokine IL-8 are normally produced by IEL and LPL in both small and large intestine. Activation in vitro enhanced IFN-γ and TGF-β1 production and induced IL-10. These data indicate ongoing controlled cell mediated immune activity and readiness for both pro-inflammatory and immunosuppressive responses. (2) IEL and LPL of both small and large intestine exhibited a capacity to kill via the Fas/FasL pathway in a T cell antigen receptor (TCR)/CD3 independent manner. FasL expressing cells were present both intraepithelially and in LP and were most abundant in LP of colon, where they constitute 30% of the immune cells. These results suggest that local immune activity in the intestinal mucosa is controlled by activation induced cell death, AICD. Small intestinal mucosa harbours a small population of CD8+ αβ+T lymphocytes with cytolytic machinery that can be triggered through the TCR/CD3 complex. These T cells use the perforin/granzyme exocytosis pathway for killing. Such cells are not detected in colon. Most probably these cytotoxic T lymphocytes are "caught in the act" of eliminating virus infected epithelial cells. (3) Inflammation in colon leads to activation of γδ T cells. In UC, Vδ1+ γδ T cells, which normally reside within the epithelium, were numerous in LP. They constituted as much as 15% of the cells in the lymphoid aggregates and showed TCR-γδ internalisation and surface down-regulation, signs of receptor mediated activation. Thus, γδ T cells appear to be recruited from the epithelium in response to nominal antigens present in LP. (4) The cytokine profile of LP T cells was markedly distorted in UC patients and regulatory T cells were induced. IL-10 production was increased and expression levels correlated with disease activity while TGF-β1 levels were unchanged. CD4+ T cells were the major source of IL-10. Moreover, cells with the regulatory/suppressor phenotype CD4+CD28-TCR-αβ+ were frequent, particularly in the aggregates. IL-2 production was shut off and production of IFN-γ and TNF-α was decreased. However, we found no evidence for a corresponding induction of the Th2 cytokines. (5) There was a parallel accumulation of FasL expressing cells with retained capacity to kill via the Fas/FasL pathway and apoptosis resistant bcl-2 expressing lymphocytes in UC. Inflammation in ileum of CD patients led to an enhanced cytotoxicity. The frequency of perforin expressing LPL was increased and the capacity of LPL to execute TCR/CD3 mediated cytotoxicity via the perforin exocytosis pathway was elevated.In summary, it appears that intestinal T lymphocytes are constantly involved in cell mediated immune activities and that cytotoxic memory CD8+ αβ T cells accumulate in the small intestinal mucosa. IEL and LPL seem capable of down-regulatory actions in the context of proinflammatory cytokines and the local homeostasis of immune reactions to luminal components seems to be regulated by IL-2 dependent AICD. The cytokine profile in UC suggests a generalised activation of regulatory T cells along the intestine. Inflammation in colon, but not in ileum, point to the importance of colonic microflora for precipitating the proinflammatory actions of IL-10.
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| 9. |
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| 10. |
- Melgar, Silvia, et al.
(author)
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Mice with experimental colitis show an altered metabolism with decreased metabolic rate
- 2007
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In: AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY. - : American Physiological Society. - 0193-1857 .- 1522-1547. ; 292:1
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Journal article (peer-reviewed)abstract
- Patients with inflammatory bowel disease (IBD) suffer from body weight loss, malnutrition, and several other metabolic alterations affecting their quality of life. The aim of this study was to investigate the metabolic changes that may occur during acute and chronic colonic inflammation induced by dextran sulfate sodium (DSS) in mice. Clinical symptoms and inflammatory markers revealed the presence of an ongoing inflammatory response in the DSS-treated mice. Mice with acute inflammation had decreased body weight, respiratory exchange ratios (RER), food intake, and body fat content. Mice with chronic inflammation had decreased nutrient uptake, body fat content, locomotor activity, metabolic rates, and bone mineral density. Despite this, the body weight, food and water intake, lean mass, and RER of these mice returned to values similar to those in healthy controls. Thus, murine experimental colitis is associated with significant metabolic alterations similar to IBD patients. Our data show that the metabolic responses during acute and chronic inflammation are different, although the metabolic rate is reduced in both phases. These observations suggest compensatory metabolic alterations in chronic colitis resulting in a healthy appearance despite gross colon pathology.
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| 11. |
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| 12. |
- Myrelid, Pär, et al.
(author)
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Effects of Anti-Inflammatory Therapy on Bursting Pressure of colonic Anastomosis in Dextran Sulfate Sodium Induced Colitis in Mice
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Other publication (other academic/artistic)abstract
- Background: The aim of this experimental study was to evaluate the effect of colitis and anti inflammatory therapies, respectively, on the healing of colonic anastomoses in mice. Methods: Eighty four female C57BL/6 mice where randomized into eight groups; four groups continued receiving plain tap water and four groups receiving dextran sulfate sodium. Intraperitoneal treatment was given for 14 days with placebo, prednisolone (2 mg/kg bodyweight), azathioprine (5 mg/kg bodyweight) or infliximab (5 mg/kg bodyweight) until surgery with transsection of the colon and an end to end colonic anastomosis was performed. All mice were sacrificed on day 2 and bursting pressure measurements were recorded. Results: In the DSS group the mice receiving placebo (n=4) had a more active inflammation with a bowel weight of 12.8 (10.6-15.0) mg/mm, which differed significantly from all the other therapy arms; prednisolone 8.1 (7.5-9.1) mg/mm (p=0.014), azathioprine 8.2 (7.0-8.5) mg/mm (p=0.0046), infliximab 6.7 (6.4-7.9) mg/mm (p=0.0055). Bursting pressure for the placebo group was 90.0 (71.5-102.8) mmHg and did not differ from the azathioprine or infliximab groups, 84.4 (70.5-112.5) and 92.3 (75.8-122.3) mmHg respectively. In contrast bursting pressure for the prednisolone-treated group was decreased compared to placebo, 55.5 (42.8-73.0) mmHg (p=0.0004), as well as compared with azathioprine (p=0.0004) and infliximab (p=0.0015). Conclusions: All given therapies had effect on the DSS-induced colitis. A severe decrease in bursting pressure of a colonic anastomosis was seen after preoperative steroids but we found no effect of azathioprine or infliximab. Thus, AZA and IFX may not increase the risk for anastomotic complications per se; the need for these therapies may rather be seen as markers of severe IBD with increased risk of surgical complications.
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| 13. |
- Myrelid, Pär, et al.
(author)
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Effects of anti-inflammatory therapy on bursting pressure of colonic anastomosis in murine dextran sulfate sodium induced colitis
- 2015
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In: Scandinavian Journal of Gastroenterology. - : TAYLOR and FRANCIS LTD. - 0036-5521 .- 1502-7708. ; 50:8, s. 991-1001
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Journal article (peer-reviewed)abstract
- Background. The aim of this study was to examine the effect of colitis and anti-inflammatory therapies on the healing of colonic anastomoses in mice. Methods. Female C57BL/6 mice were randomized into eight groups; four groups receiving plain tap-water and four groups receiving dextran sulfate sodium. Intra-peritoneal treatment was given therapeutically for 14 days with placebo, prednisolone, azathioprine, or infliximab (IFX). Colonic anastomoses were performed and bursting pressure (BP) measurements were recorded and the inflammation evaluated with histology and zymography. Results. The mice with colitis had a more active inflammation based on histology and bowel weight compared with the tap water group, 8.3 (7.6-9.5) mg/mm and 5.5 (4.8-6.2) mg/mm respectively (p less than 0.0001). Similarly mice with colitis receiving placebo had a more active inflammation, 12.8 (10.6-15.0) mg/mm, which differed significantly from all the other therapy arms among the colitic mice; prednisolone 8.1 (7.5-9.1) mg/mm (p = 0.014), azathioprine 8.2 (7.0-8.5) mg/mm (p = 0.0046), IFX 6.7 (6.4-7.9) mg/mm (p = 0.0055). BP for the placebo group was 90.0 (71.5-102.8) mmHg and did not differ from azathioprine or IFX groups, 84.4 (70.5-112.5) and 92.3 (75.8-122.3) mmHg respectively. In contrast BP for the prednisolone group was significantly decreased compared to placebo, 55.5 (42.8-73.0) mmHg (p = 0.0004). Conclusions. All therapies had a beneficial effect on the colitis. An impaired BP of colonic anastomoses was noted after preoperative steroids but not after azathioprine or IFX in this model.
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