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Protection of eukaryotic cells against pore-forming toxins from pathogenic bacteria / THOMAS ORMSBY

Swansea University Author: THOMAS ORMSBY

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DOI (Published version): 10.23889/SUthesis.59035

Abstract

Bacterial infections are a leading cause of mortality and morbidity. Many species of pathogenic bacteria secrete pore-forming toxins to damage eukaryotic cells and facilitate pathogen invasion. Although cells can repair this damage, little is known about the intrinsic protection of cells against the...

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Published: Swansea 2021
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
Supervisor: Sheldon, I. Martin ; Cronin, James G.
URI: https://cronfa.swan.ac.uk/Record/cronfa59035
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first_indexed 2021-12-21T15:49:29Z
last_indexed 2021-12-22T04:26:40Z
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fullrecord <?xml version="1.0"?><rfc1807><datestamp>2021-12-21T16:24:46.4651921</datestamp><bib-version>v2</bib-version><id>59035</id><entry>2021-12-21</entry><title>Protection of eukaryotic cells against pore-forming toxins from pathogenic bacteria</title><swanseaauthors><author><sid>559dbd7b55ce6aa38eca17712d4f06c5</sid><firstname>THOMAS</firstname><surname>ORMSBY</surname><name>THOMAS ORMSBY</name><active>true</active><ethesisStudent>false</ethesisStudent></author></swanseaauthors><date>2021-12-21</date><abstract>Bacterial infections are a leading cause of mortality and morbidity. Many species of pathogenic bacteria secrete pore-forming toxins to damage eukaryotic cells and facilitate pathogen invasion. Although cells can repair this damage, little is known about the intrinsic protection of cells against these toxins. Side-chain oxysterols and steroids can reduce the severity of bacterial diseases by suppressing immunity. Here we tested the hypothesis that oxysterols and steroids might also enhance the intrinsic protection of eukaryotic cells against pore-forming toxins. We first used the cholesterol-dependent cytolysin pyolysin, which forms pores in bovine endometrial cells. We found that 25-hydroxycholesterol or 27-hydroxycholesterol treatment protected bovine endometrial cells against pyolysin, and that these oxysterols are present in the reproductive tract. The oxysterols reduced pyolysin-induced leakage of potassium and lactate dehydrogenase by &gt; 65%, limited changes to the actin cytoskeleton, and prevented cytolysis. The oxysterols also protected human cervical, lung, and liver epithelial cells against pyolysin damage, and protected cells against Staphylococcus aureus &#x3B1;-hemolysin. Mechanistically, oxysterol cytoprotection was partially dependent on activating acetyl-coenzyme A acetyltransferase and liver X receptors. The steroids, progesterone, oestradiol, or hydrocortisone were not protective in bovine endometrial cells. However, hydrocortisone and dexamethasone protected several types of human cells against pyolysin, reducing cytolysis from &gt; 75% to &lt; 25%, via a glucocorticoid receptor dependent mechanism. Treatment with these glucocorticoids also protected human cells against &#x3B1;-hemolysin and another cholesterol-dependent cytolysin, streptolysin O. However, glucocorticoid cytoprotection was reversibly blocked by the presence of &#x2265; 4% serum, which led to the discovery that glucocorticoid cytoprotection depended on the rate limiting enzyme of cholesterol biosynthesis, 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase. In conclusion, side-chain oxysterols and glucocorticoids enhance the intrinsic protection of eukaryotic cells against pore-forming toxins. These findings imply that oxysterols and glucocorticoids could help limit the severity of disease caused by pathogens that secrete pore-forming toxins.</abstract><type>E-Thesis</type><journal/><volume/><journalNumber/><paginationStart/><paginationEnd/><publisher/><placeOfPublication>Swansea</placeOfPublication><isbnPrint/><isbnElectronic/><issnPrint/><issnElectronic/><keywords>Pore-forming toxins, cholesterol-dependent cytolysins, cytoprotection, oxysterols, glucocorticoids</keywords><publishedDay>21</publishedDay><publishedMonth>12</publishedMonth><publishedYear>2021</publishedYear><publishedDate>2021-12-21</publishedDate><doi>10.23889/SUthesis.59035</doi><url/><notes>A selection of third party content is redacted or is partially redacted from this thesis due to copyright restrictions.ORCiD identifier: https://orcid.org/0000-0003-4371-5316</notes><college>COLLEGE NANME</college><CollegeCode>COLLEGE CODE</CollegeCode><institution>Swansea University</institution><supervisor>Sheldon, I. Martin ; Cronin, James G.</supervisor><degreelevel>Doctoral</degreelevel><degreename>Ph.D</degreename><degreesponsorsfunders>National Institutes of Health, grant number R01HD084316</degreesponsorsfunders><apcterm/><lastEdited>2021-12-21T16:24:46.4651921</lastEdited><Created>2021-12-21T15:34:28.1982313</Created><path><level id="1">Faculty of Medicine, Health and Life Sciences</level><level id="2">Swansea University Medical School - Medicine</level></path><authors><author><firstname>THOMAS</firstname><surname>ORMSBY</surname><order>1</order></author></authors><documents><document><filename>59035__21932__11bb86ca4b8c4e448365e64406b2b4c0.pdf</filename><originalFilename>Ormsby_Thomas_J_R_PhD_Thesis_Final_Redacted.pdf</originalFilename><uploaded>2021-12-21T16:07:46.8474775</uploaded><type>Output</type><contentLength>15425010</contentLength><contentType>application/pdf</contentType><version>Redacted version - open access</version><cronfaStatus>true</cronfaStatus><documentNotes>Copyright: The author, Thomas J. R. Ormsby, 2021.</documentNotes><copyrightCorrect>true</copyrightCorrect><language>eng</language></document></documents><OutputDurs/></rfc1807>
spelling 2021-12-21T16:24:46.4651921 v2 59035 2021-12-21 Protection of eukaryotic cells against pore-forming toxins from pathogenic bacteria 559dbd7b55ce6aa38eca17712d4f06c5 THOMAS ORMSBY THOMAS ORMSBY true false 2021-12-21 Bacterial infections are a leading cause of mortality and morbidity. Many species of pathogenic bacteria secrete pore-forming toxins to damage eukaryotic cells and facilitate pathogen invasion. Although cells can repair this damage, little is known about the intrinsic protection of cells against these toxins. Side-chain oxysterols and steroids can reduce the severity of bacterial diseases by suppressing immunity. Here we tested the hypothesis that oxysterols and steroids might also enhance the intrinsic protection of eukaryotic cells against pore-forming toxins. We first used the cholesterol-dependent cytolysin pyolysin, which forms pores in bovine endometrial cells. We found that 25-hydroxycholesterol or 27-hydroxycholesterol treatment protected bovine endometrial cells against pyolysin, and that these oxysterols are present in the reproductive tract. The oxysterols reduced pyolysin-induced leakage of potassium and lactate dehydrogenase by > 65%, limited changes to the actin cytoskeleton, and prevented cytolysis. The oxysterols also protected human cervical, lung, and liver epithelial cells against pyolysin damage, and protected cells against Staphylococcus aureus α-hemolysin. Mechanistically, oxysterol cytoprotection was partially dependent on activating acetyl-coenzyme A acetyltransferase and liver X receptors. The steroids, progesterone, oestradiol, or hydrocortisone were not protective in bovine endometrial cells. However, hydrocortisone and dexamethasone protected several types of human cells against pyolysin, reducing cytolysis from > 75% to < 25%, via a glucocorticoid receptor dependent mechanism. Treatment with these glucocorticoids also protected human cells against α-hemolysin and another cholesterol-dependent cytolysin, streptolysin O. However, glucocorticoid cytoprotection was reversibly blocked by the presence of ≥ 4% serum, which led to the discovery that glucocorticoid cytoprotection depended on the rate limiting enzyme of cholesterol biosynthesis, 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase. In conclusion, side-chain oxysterols and glucocorticoids enhance the intrinsic protection of eukaryotic cells against pore-forming toxins. These findings imply that oxysterols and glucocorticoids could help limit the severity of disease caused by pathogens that secrete pore-forming toxins. E-Thesis Swansea Pore-forming toxins, cholesterol-dependent cytolysins, cytoprotection, oxysterols, glucocorticoids 21 12 2021 2021-12-21 10.23889/SUthesis.59035 A selection of third party content is redacted or is partially redacted from this thesis due to copyright restrictions.ORCiD identifier: https://orcid.org/0000-0003-4371-5316 COLLEGE NANME COLLEGE CODE Swansea University Sheldon, I. Martin ; Cronin, James G. Doctoral Ph.D National Institutes of Health, grant number R01HD084316 2021-12-21T16:24:46.4651921 2021-12-21T15:34:28.1982313 Faculty of Medicine, Health and Life Sciences Swansea University Medical School - Medicine THOMAS ORMSBY 1 59035__21932__11bb86ca4b8c4e448365e64406b2b4c0.pdf Ormsby_Thomas_J_R_PhD_Thesis_Final_Redacted.pdf 2021-12-21T16:07:46.8474775 Output 15425010 application/pdf Redacted version - open access true Copyright: The author, Thomas J. R. Ormsby, 2021. true eng
title Protection of eukaryotic cells against pore-forming toxins from pathogenic bacteria
spellingShingle Protection of eukaryotic cells against pore-forming toxins from pathogenic bacteria
THOMAS ORMSBY
title_short Protection of eukaryotic cells against pore-forming toxins from pathogenic bacteria
title_full Protection of eukaryotic cells against pore-forming toxins from pathogenic bacteria
title_fullStr Protection of eukaryotic cells against pore-forming toxins from pathogenic bacteria
title_full_unstemmed Protection of eukaryotic cells against pore-forming toxins from pathogenic bacteria
title_sort Protection of eukaryotic cells against pore-forming toxins from pathogenic bacteria
author_id_str_mv 559dbd7b55ce6aa38eca17712d4f06c5
author_id_fullname_str_mv 559dbd7b55ce6aa38eca17712d4f06c5_***_THOMAS ORMSBY
author THOMAS ORMSBY
author2 THOMAS ORMSBY
format E-Thesis
publishDate 2021
institution Swansea University
doi_str_mv 10.23889/SUthesis.59035
college_str Faculty of Medicine, Health and Life Sciences
hierarchytype
hierarchy_top_id facultyofmedicinehealthandlifesciences
hierarchy_top_title Faculty of Medicine, Health and Life Sciences
hierarchy_parent_id facultyofmedicinehealthandlifesciences
hierarchy_parent_title Faculty of Medicine, Health and Life Sciences
department_str Swansea University Medical School - Medicine{{{_:::_}}}Faculty of Medicine, Health and Life Sciences{{{_:::_}}}Swansea University Medical School - Medicine
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description Bacterial infections are a leading cause of mortality and morbidity. Many species of pathogenic bacteria secrete pore-forming toxins to damage eukaryotic cells and facilitate pathogen invasion. Although cells can repair this damage, little is known about the intrinsic protection of cells against these toxins. Side-chain oxysterols and steroids can reduce the severity of bacterial diseases by suppressing immunity. Here we tested the hypothesis that oxysterols and steroids might also enhance the intrinsic protection of eukaryotic cells against pore-forming toxins. We first used the cholesterol-dependent cytolysin pyolysin, which forms pores in bovine endometrial cells. We found that 25-hydroxycholesterol or 27-hydroxycholesterol treatment protected bovine endometrial cells against pyolysin, and that these oxysterols are present in the reproductive tract. The oxysterols reduced pyolysin-induced leakage of potassium and lactate dehydrogenase by > 65%, limited changes to the actin cytoskeleton, and prevented cytolysis. The oxysterols also protected human cervical, lung, and liver epithelial cells against pyolysin damage, and protected cells against Staphylococcus aureus α-hemolysin. Mechanistically, oxysterol cytoprotection was partially dependent on activating acetyl-coenzyme A acetyltransferase and liver X receptors. The steroids, progesterone, oestradiol, or hydrocortisone were not protective in bovine endometrial cells. However, hydrocortisone and dexamethasone protected several types of human cells against pyolysin, reducing cytolysis from > 75% to < 25%, via a glucocorticoid receptor dependent mechanism. Treatment with these glucocorticoids also protected human cells against α-hemolysin and another cholesterol-dependent cytolysin, streptolysin O. However, glucocorticoid cytoprotection was reversibly blocked by the presence of ≥ 4% serum, which led to the discovery that glucocorticoid cytoprotection depended on the rate limiting enzyme of cholesterol biosynthesis, 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase. In conclusion, side-chain oxysterols and glucocorticoids enhance the intrinsic protection of eukaryotic cells against pore-forming toxins. These findings imply that oxysterols and glucocorticoids could help limit the severity of disease caused by pathogens that secrete pore-forming toxins.
published_date 2021-12-21T04:16:01Z
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score 11.037056

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