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Holm, Lena
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Publications (10 of 75) Show all publications
Shore, R., Bjorne, H., Omoto, Y., Siemiatkowska, A., Gustafsson, J.-Å., Lindblad, M. & Holm, L. (2017). Sex differences and effects of oestrogen in rat gastric mucosal defence. World Journal of Gastroenterology, 23(3), 426-436
Open this publication in new window or tab >>Sex differences and effects of oestrogen in rat gastric mucosal defence
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2017 (English)In: World Journal of Gastroenterology, ISSN 1007-9327, E-ISSN 2219-2840, Vol. 23, no 3, p. 426-436Article in journal (Refereed) Published
Abstract [en]

AIM To evaluate sex differences and the effects of oestrogen administration in rat gastric mucosal defence. METHODS Sex differences in gastric mucus thickness and accumulation rate, absolute gastric mucosal blood flow using microspheres, the integrity of the gastric mucosal epithelium in response to a chemical irritant and the effects of oestrogen administration on relative gastric mucosal blood flow in an acute setting was assessed in an in vivo rat experimental model. Subsequently, sex differences in the distribution of oestrogen receptors and calcitonin gene related peptide in the gastric mucosa of animals exposed to oestrogen in the above experiments was evaluated using immunohistochemistry. RESULTS The absolute blood flow in the GI-tract was generally higher in males, but only significantly different in the corpus part of the stomach (1.12 +/- 0.12 mL/min.g in males and 0.51 +/- 0.03 mL/min.g in females) (P = 0.002). After removal of the loosely adherent mucus layer the thickness of the firmly adherent mucus layer in males and females was 79 +/- 1 mu m and 80 +/- 3 mu m respectively. After 60 min the mucus thickness increased to 113 +/- 3 mu m in males and 121 +/- 3 mu m in females with no statistically significant difference seen between the sexes. Following oestrogen administration (0.1 followed by 1 mu g/kg.min), mean blood flow in the gastric mucosa decreased by 31% [68 +/- 13 perfusion units (PFU)] in males which was significantly different compared to baseline (P = 0.02). In females however, mean blood flow remained largely unchanged with a 4% (5 +/- 33 PFU) reduction. The permeability of the gastric mucosa increased to a higher level in females than in males (P = 0.01) after taurocholate challenge. However, the calculated mean clearance increase did not significantly differ between the sexes [0.1 +/- 0.04 to 1.1 +/- 0.1 mL/min.100 g in males and 0.4 +/- 0.3 to 2.1 +/- 0.3 mL/min.100 g in females (P = 0.065)]. There were no significant differences between 17 beta-Estradiol treated males (mean ratio of positive staining +/- SEM) (0.06 +/- 0.07) and females (0.11 +/- 0.11) in the staining of ER alpha (P = 0.24). Also, there were no significant differences between 17 beta-Estradiol treated males (0.18 +/- 0.21) and females (0.06 +/- 0.12) in the staining of ER beta (P = 0.11). Finally, there were no significant differences between 17 beta-Estradiol treated males (0.04 +/- 0.05) and females (0.11 +/- 0.10) in the staining of CGRP (P = 0.14). CONCLUSION Gastric mucosal blood flow is higher in male than in female rats and is reduced in male rats by oestrogen administration.

Keyword
Sex differences, Gastric mucosal defence, Blood flow, Oestrogen, Gastric physiology, Mucus
National Category
Gastroenterology and Hepatology
Identifiers
urn:nbn:se:uu:diva-316024 (URN)10.3748/wjg.v23.i3.426 (DOI)000391956000005 ()
Available from: 2017-02-24 Created: 2017-02-24 Last updated: 2017-11-29Bibliographically approved
Karimi, S., Ahl, D., Vagesjö, E., Holm, L., Phillipson, M., Jonsson, H. & Roos, S. (2016). In Vivo and In Vitro Detection of Luminescent and Fluorescent Lactobacillus reuteri and Application of Red Fluorescent mCherry for Assessing Plasmid Persistence. PLoS ONE, 11(3), Article ID e0151969.
Open this publication in new window or tab >>In Vivo and In Vitro Detection of Luminescent and Fluorescent Lactobacillus reuteri and Application of Red Fluorescent mCherry for Assessing Plasmid Persistence
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2016 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 3, article id e0151969Article in journal (Refereed) Published
Abstract [en]

Lactobacillus reuteri is a symbiont that inhabits the gastrointestinal (GI) tract of mammals, and several strains are used as probiotics. After introduction of probiotic strains in a complex ecosystem like the GI tract, keeping track of them is a challenge. The main objectives of this study were to introduce reporter proteins that would enable in vivo and in vitro detection of L. reuteri and increase knowledge about its interactions with the host. We describe for the first time cloning of codon-optimized reporter genes encoding click beetle red luciferase (CBRluc) and red fluorescent protein mCherry in L. reuteri strains ATCC PTA 6475 and R2LC. The plasmid persistence of mCherry-expressing lactobacilli was evaluated by both flow cytometry (FCM) and conventional plate count (PC), and the plasmid loss rates measured by FCM were lower overall than those determined by PC. Neutralization of pH and longer induction duration significantly improved the mCherry signal. The persistency, dose-dependent signal intensity and localization of the recombinant bacteria in the GI tract of mice were studied with an in vivo imaging system (IVIS), which allowed us to detect fluorescence from 6475-CBRluc-mCherry given at a dose of 1x10(10) CFU and luminescence signals at doses ranging from 1x10(5) to 1x10(10) CFU. Both 6475-CBRluc-mCherry and R2LC-CBRluc were localized in the colon 1 and 2 h after ingestion, but the majority of the latter were still found in the stomach, possibly reflecting niche specificity for R2LC. Finally, an in vitro experiment showed that mCherry-producing R2LC adhered efficiently to the intra cellular junctions of cultured IPEC-J2 cells. In conclusion, the two reporter genes CBRluc and mCherry were shown to be suitable markers for biophotonic imaging (BPI) of L. reuteri and may provide useful tools for future studies of in vivo and in vitro interactions between the bacteria and the host.

National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:uu:diva-286655 (URN)10.1371/journal.pone.0151969 (DOI)000372697400062 ()27002525 (PubMedID)
Available from: 2016-04-27 Created: 2016-04-21 Last updated: 2018-01-10Bibliographically approved
Ahl, D., Liu, H., Schreiber, O., Roos, S., Phillipson, M. & Holm, L. (2016). Lactobacillus reuteri increases mucus thickness and ameliorates dextran sulphate sodium-induced colitis in mice. Acta Physiologica, 217(4), 300-310
Open this publication in new window or tab >>Lactobacillus reuteri increases mucus thickness and ameliorates dextran sulphate sodium-induced colitis in mice
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2016 (English)In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 217, no 4, p. 300-310Article in journal (Refereed) Published
Abstract [en]

Aim: The aim of this study was to investigate whether two Lactobacillus reuteri strains (rat-derived R2LC and human-derived ATCC PTA 4659 (4659)) could protect mice against colitis, as well as delineate the mechanisms behind this protection.

Methods: Mice were given L.reuteri R2LC or 4659 by gavage once daily for 14days, and colitis was induced by addition of 3% DSS (dextran sulphate sodium) to drinking water for the last 7days of this period. The severity of disease was assessed through clinical observations, histological evaluation and ELISA measurements of myeloperoxidase (MPO) and pro-inflammatory cytokines from colonic samples. Mucus thickness was measured invivo with micropipettes, and tight junction protein expression was assessed using immunohistochemistry.

Results: Colitis severity was significantly reduced by L.reuteri R2LC or 4659 when evaluated both clinically and histologically. The inflammation markers MPO, IL-1, IL-6 and mKC (mouse keratinocyte chemoattractant) were increased by DSS and significantly reduced by the L.reuteri strains. The firmly adherent mucus thickness was reduced by DSS, but significantly increased by L.reuteri in both control and DSS-treated mice. Expression of the tight junction proteins occludin and ZO-1 was significantly increased in the bottom of the colonic crypts by L.reuteri R2LC.

Conclusion: These results demonstrate that each of the two different L. reuteri strains, one human-derived and one-rat-derived, protects against colitis in mice. Mechanisms behind this protection could at least partly be explained by the increased mucus thickness as well as a tightened epithelium in the stem cell area of the crypts.

Keyword
colon, dextran sulphate sodium, inflammatory bowel disease, mucus thickness, probiotics, tight junctions
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-301010 (URN)10.1111/apha.12695 (DOI)000379972300007 ()27096537 (PubMedID)
Available from: 2016-08-17 Created: 2016-08-17 Last updated: 2017-11-28Bibliographically approved
Petersson, J., Jadert, C., Phillipson, M., Borniquel, S., Lundberg, J. O. & Holm, L. (2015). Physiological recycling of endogenous nitrate by oral bacteria regulates gastric mucus thickness. Free Radical Biology & Medicine, 89, 241-247
Open this publication in new window or tab >>Physiological recycling of endogenous nitrate by oral bacteria regulates gastric mucus thickness
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2015 (English)In: Free Radical Biology & Medicine, ISSN 0891-5849, E-ISSN 1873-4596, Vol. 89, p. 241-247Article in journal (Refereed) Published
Abstract [en]

Background: Inorganic nitrate from exogenous and endogenous sources is accumulated in saliva, reduced to nitrite by oral bacteria and further converted to nitric oxide (NO) and other bioactive nitrogen oxides in the acidic gastric lumen. To further explore the role of oral microbiota in this process we examined the gastric mucus layer in germ free (GF) and conventional mice given different doses of nitrate and nitrite. Methods: Mice were given either nitrate (100 mg/kg/d) or nitrite (0.55-11 mg/kg/d) in the drinking water for 7 days, with the lowest nitrite dose resembling the levels provided by swallowing of fasting saliva. The gastric mucus layer was measured in vivo. Results: GF animals were almost devoid of the firmly adherent mucus layer compared to conventional mice. Dietary nitrate increased the mucus thickness in conventional animals but had no effect in GF mice. In contrast, nitrite at all doses, restored the mucus thickness in GF mice to the same levels as in conventional animals. The nitrite-mediated increase in gastric mucus thickness was not inhibited by the soluble guanylyl cyclase inhibitor ODQ. Mice treated with antibiotics had significantly thinner mucus than controls. Additional studies on mucin gene expression demonstrated down regulation of Muc5ac and Much in germ free mice after nitrite treatment. Conclusion: Oral bacteria remotely modulate gastric mucus generation via bioactivation of salivary nitrate. In the absence of a dietary nitrate intake, salivary nitrate originates mainly from NO synthase. Thus, oxidized NO from the endothelium and elsewhere is recycled to regulate gastric mucus homeostasis.

Keyword
Nitric oxide, Nitrosothiols, Gut microbiota, Nitrite, Ulcer
National Category
Physiology
Identifiers
urn:nbn:se:uu:diva-274292 (URN)10.1016/j.freeradbiomed.2015.07.003 (DOI)000366355800023 ()
Funder
Torsten Söderbergs stiftelseSwedish Research Council, 08646
Available from: 2016-01-26 Created: 2016-01-20 Last updated: 2018-01-10Bibliographically approved
Granger, D. N., Holm, L. & Kvietys, P. (2015). The Gastrointestinal Circulation: Physiology and Pathophysiology. COMPREHENSIVE PHYSIOLOGY, 5(3), 1541-1583
Open this publication in new window or tab >>The Gastrointestinal Circulation: Physiology and Pathophysiology
2015 (English)In: COMPREHENSIVE PHYSIOLOGY, ISSN 2040-4603, Vol. 5, no 3, p. 1541-1583Article in journal (Refereed) Published
Abstract [en]

The gastrointestinal (GI) circulation receives a large fraction of cardiac output and this increases following ingestion of a meal. While blood flow regulation is not the intense phenomenon noted in other vascular beds, the combined responses of blood flow, and capillary oxygen exchange help ensure a level of tissue oxygenation that is commensurate with organ metabolism and function. This is evidenced in the vascular responses of the stomach to increased acid production and in intestine during periods of enhanced nutrient absorption. Complimenting the metabolic vasoregulation is a strong myogenic response that contributes to basal vascular tone and to the responses elicited by changes in intravascular pressure. The GI circulation also contributes to a mucosal defense mechanism that protects against excessive damage to the epithelial lining following ingestion of toxins and/or noxious agents. Profound reductions in GI blood flow are evidenced in certain physiological (strenuous exercise) and pathological (hemorrhage) conditions, while some disease states (e.g., chronic portal hypertension) are associated with a hyperdynamic circulation. The sacrificial nature of GI blood flow is essential for ensuring adequate perfusion of vital organs during periods of whole body stress. The restoration of blood flow (reperfusion) to GI organs following ischemia elicits an exaggerated tissue injury response that reflects the potential of this organ system to generate reactive oxygen species and to mount an inflammatory response. Human and animal studies of inflammatory bowel disease have also revealed a contribution of the vasculature to the initiation and perpetuation of the tissue inflammation and associated injury response. (C) 2015 American Physiological Society.

National Category
Physiology
Identifiers
urn:nbn:se:uu:diva-259661 (URN)10.1002/cphy.c150007 (DOI)000357596400020 ()26140727 (PubMedID)
Note

Funding: National Heart Lung and Blood Institute, King Abdulaziz City for Science and Technology

Available from: 2015-08-20 Created: 2015-08-10 Last updated: 2018-01-11Bibliographically approved
Ahl, D., Roos, S., Phillipson, M. & Holm, L. (2014). CX3CR1 deficiency alters response to L-reuteri treatment of DSS-induced colitis in mice. Paper presented at EXPERIMENTAL BIOLOGY 2014 - Transforming the Future through Science, EB, April 26-30, 2014, Sand Diego, USA. The FASEB Journal, 28(1), Article ID 902.10.
Open this publication in new window or tab >>CX3CR1 deficiency alters response to L-reuteri treatment of DSS-induced colitis in mice
2014 (English)In: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 28, no 1, article id 902.10Article in journal, Meeting abstract (Other academic) Published
National Category
Biological Sciences
Identifiers
urn:nbn:se:uu:diva-246749 (URN)000346651003277 ()
Conference
EXPERIMENTAL BIOLOGY 2014 - Transforming the Future through Science, EB, April 26-30, 2014, Sand Diego, USA
Available from: 2015-03-10 Created: 2015-03-10 Last updated: 2017-12-04Bibliographically approved
Jädert, C., Phillipson, M., Holm, L., Lundberg, J. O. & Borniquel, S. (2014). Preventive and therapeutic effects of nitrite supplementation in experimental inflammatory bowel disease. Redox biology, 2, 73-81
Open this publication in new window or tab >>Preventive and therapeutic effects of nitrite supplementation in experimental inflammatory bowel disease
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2014 (English)In: Redox biology, ISSN 2213-2317, Vol. 2, p. 73-81Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Inorganic nitrate and nitrite have emerged as alternative substrates for nitric oxide (NO) generation in the gastrointestinal tract, and have shown to be protective against drug-induced gastric injury. The aim of this study was to investigate the preventive and therapeutic effects of nitrate and nitrite in a model of experimental colitis.

METHODS: Colitis was induced in mice by administrating dextran sulfate sodium (DSS) with concurrent administration of nitrite (1 mM) or nitrate (10 mM) in the drinking water for 7 days. A therapeutic approach was also investigated by initiating nitrite treatment 3 days after DSS-induced colitis. Clinical and inflammatory markers were assessed and the colonic mucus thickness was measured in vivo. The effect of nitrite on wound healing was evaluated using colon epithelial cells.

RESULTS: Concurrent administration of DSS and nitrite (1 mM) alleviated inflammation as determined by reduced disease activity index score (DAI) and increased colon length, while nitrate (10 mM) only reduced the DAI-score. Nitrite also displayed therapeutic effects by ameliorating established colonic inflammation with reduced colonic expression of iNOS and improving histopathology. DSS-induced decrease in colonic mucus thickness was completely prevented by nitrite administration. In addition, goblet cell abundance was lower by DSS treatment, but was increased by addition of nitrite. Further studies using colon epithelial cells revealed an NO-dependent improvement in wound healing with nitrite administration.

CONCLUSION: Nitrite exerts both preventive and therapeutic effects in colonic inflammation. The protective effects involve preservation of an intact adherent mucus layer and regulation of epithelial cell restitution.

National Category
Biological Sciences
Identifiers
urn:nbn:se:uu:diva-220700 (URN)10.1016/j.redox.2013.12.012 (DOI)000350769600011 ()24494186 (PubMedID)
Available from: 2014-04-07 Created: 2014-03-19 Last updated: 2015-04-24Bibliographically approved
Vågesjö, E., Christoffersson, G., Korsgren, O., Essand, M., Holm, L. & Phillipson, M. (2014). Strategical steering of the immune system: induction of leukocyte vascular chaperoning increases functional blood flow responses in ischemic muscle. Paper presented at Experimental Biology Meeting, APR 26-30, 2014, San Diego, CA. The FASEB Journal, 28(1), Article ID 670.6.
Open this publication in new window or tab >>Strategical steering of the immune system: induction of leukocyte vascular chaperoning increases functional blood flow responses in ischemic muscle
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2014 (English)In: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 28, no 1, article id 670.6Article in journal, Meeting abstract (Other academic) Published
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:uu:diva-246842 (URN)000346646703065 ()
Conference
Experimental Biology Meeting, APR 26-30, 2014, San Diego, CA
Available from: 2015-03-10 Created: 2015-03-10 Last updated: 2017-12-04Bibliographically approved
Kober, O., Ahl, D., Pin, C., Holm, L., Carding, S. R. & Juge, N. (2014). γδ T-cell-deficient mice show alterations in mucin expression, glycosylation and goblet cells but maintain an intact mucus layer.. American Journal of Physiology - Gastrointestinal and Liver Physiology, 306(7), G582-G593
Open this publication in new window or tab >>γδ T-cell-deficient mice show alterations in mucin expression, glycosylation and goblet cells but maintain an intact mucus layer.
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2014 (English)In: American Journal of Physiology - Gastrointestinal and Liver Physiology, ISSN 0193-1857, E-ISSN 1522-1547, Vol. 306, no 7, p. G582-G593Article in journal (Refereed) Published
Abstract [en]

Intestinal homeostasis is maintained by a hierarchy of immune defences acting in concert to minimize contact between luminal microorganisms and the intestinal epithelial cell surface. The intestinal mucus layer, covering the gastrointestinal (GI) tract epithelial cells, contributes to mucosal homeostasis by limiting bacterial invasion. In this study, we used γδ T-cell-deficient (TCRδ(-/-)) mice to examine whether and how γδ T-cells modulate the properties of the intestinal mucus layer. Increased susceptibility of TCRδ(-/-) mice to dextran sodium sulphate (DSS)-induced colitis is associated with a reduced number of goblet cells. Alterations in the number of goblet cells and crypt lengths were observed in the small intestine (SI) and colon of TCRδ(-/-) mice compared to C57BL/6 wt mice. Addition of keratinocyte growth factor (KGF) to small intestinal organoid cultures from TCRδ(-/-) mice showed a marked increase in crypt growth, and both goblet cell number and redistribution along the crypts. There was no apparent difference in the thickness or organisation of the mucus layer between TCRδ(-/-) and wt mice, as measured in vivo. However, γδ T-cell deficiency led to reduced sialylated mucins in association with increased gene expression of gel-secreting Muc2 and membrane-bound mucins, including Muc13 and Muc17. Collectively, these data provide evidence that γδ T cells play an important role in maintenance of mucosal homeostasis by regulating mucin expression and promoting goblet cell function in the small intestine.

National Category
Gastroenterology and Hepatology Physiology
Identifiers
urn:nbn:se:uu:diva-220702 (URN)10.1152/ajpgi.00218.2013 (DOI)000334674000004 ()24503767 (PubMedID)
Available from: 2014-04-07 Created: 2014-03-19 Last updated: 2018-01-11Bibliographically approved
Schreiber, O., Petersson, J., Walden, T., Ahl, D., Sandler, S., Phillipson, M. & Holm, L. (2013). iNOS-Dependent Increase in Colonic Mucus Thickness in DSS-Colitic Rats. PLoS ONE, 8(8), e71843
Open this publication in new window or tab >>iNOS-Dependent Increase in Colonic Mucus Thickness in DSS-Colitic Rats
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2013 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 8, p. e71843-Article in journal (Refereed) Published
Abstract [en]

Aim: To investigate colonic mucus thickness in vivo in health and during experimental inflammatory bowel disease. Methods: Colitis was induced with 5% DSS in drinking water for 8 days prior to experiment, when the descending colonic mucosa of anesthetized rats was studied using intravital microscopy. Mucus thickness was measured with micropipettes attached to a micromanipulator. To assess the contributions of NOS and prostaglandins in the regulation of colonic mucus thickness, the non-selective NOS-inhibitor L-NNA (10 mg/kg bolus followed by 3 mg/kg/h), the selective iNOS-inhibitor L-NIL (10 mg/kg bolus followed by 3 mg/kg/h) and the non-selective COX-inhibitor diclofenac (5 mg/kg) were administered intravenously prior to experiment. To further investigate the role of iNOS in the regulation of colonic mucus thickness, iNOS -/- mice were used. Results: Colitic rats had a thicker firmly adherent mucus layer following 8 days of DSS treatment than untreated rats (88 +/- 2 mu m vs 76 +/- 1 mu m). During induction of colitis, the thickness of the colonic mucus layer initially decreased but was from day 3 significantly thicker than in untreated rats. Diclofenac reduced the mucus thickness similarly in colitic and untreated rats (-16 +/- 5 mu m vs -14 +/- 2 mu m). While L-NNA had no effect on colonic mucus thickness in DSS or untreated controls (+3 +/- 2 mm vs +3 +/- 1 mu m), L-NIL reduced the mucus thickness significantly more in colitic rats than in controls (-33 +/- 4 mu m vs -10 +/- 3 mu m). The importance of iNOS in regulating the colonic mucus thickness was confirmed in iNOS-/- mice, which had thinner colonic mucus than wild-type mice (35 +/- 3 mu m vs 50 +/- 2 mu m, respectively). Furthermore, immunohistochemistry revealed increased levels of iNOS in the colonic surface epithelium following DSS treatment. Conclusion: Both prostaglandins and nitric oxide regulate basal colonic mucus thickness. During onset of colitis, the thickness of the mucus layer is initially reduced followed by an iNOS mediated increase.

National Category
Medical and Health Sciences Natural Sciences
Identifiers
urn:nbn:se:uu:diva-208083 (URN)10.1371/journal.pone.0071843 (DOI)000323425700106 ()
Available from: 2013-09-23 Created: 2013-09-23 Last updated: 2017-12-06Bibliographically approved
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