Ehrlichiosis pathophysiology: Difference between revisions
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{{Ehrlichiosis}} | {{Ehrlichiosis}} | ||
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==Overview== | |||
The pathophysiological process of ehrlichiosis begins with the inoculation of the disease from a tick vector. Following inoculation ''ehrlichiae'' and ''anaplasmosis'' enter the circulatory system in an attempt to infect a target cell. The infectious agents will then enter the cell via a receptor-mediated [[endocytosis]]. This particular endocytosis process is facilitated by a glycophoshoinositol anchored receptor. Both the ''ehrlichiae'' and ''anaplasma'' complete their reproduction process within the host cell's [[endosome]]. Infectious agents of both disease are then able to reprogram a host cell's defense mechanisms in order to silently proliferate. | |||
==Pathophysiology== | |||
===Pathogenesis of Human Monocytotropic Ehrlichiosis=== | |||
*E. chaffeensis enter into the [[Mononuclear phagocytic system|mononuclear phagocytes]]. | |||
*[[Phagolysosome]] fusion is inhibited while host genes are suppressed and induced to enable intracellular replication. | |||
*Cytokines IL-12 and IL-18 are downregulated in THP-1 cells. | |||
*Genes that are responsible for upregulation of apoptosis such as SNAP 23, Rab5A and STX16 are downregulated in correlation to the downregulation of IL-12 and IL-18. | |||
*E. chaffeensis secretes an immunoreactive ankyrin protein (200kDa) into the host's nucleus in an attempt to manipulate the gene regulation of the host cell. | |||
*Other methods of E. chaffeensis include inhibiting the signal transduction pathway and circumventing host cell defense mechanisms. | |||
*Organ failure and other pathogenic manifestations resulting in complications or death is a result of immune mediated pathology. | |||
===Pathogenesis of Human Granulocytotropic Anaplasmosis=== | |||
*A.phagocytophilum successfully resides within the host cells (PMN cells) cytoplasmic vacuoles. | |||
*Apoptosis is suppressed due to the upregulation of bfl-1 and inhibiting anti-FAS. Both of which are responsible for inducing apoptosis within [[neutrophils]]. | |||
*Host cell gene transcription is controlled through a secreted protein, AnkA, that travels into the host cell's nucleus. | |||
*Research into the pathogensis of HGA has also shown upregulation of pro-inflammatory and IL-8 chemokines. | |||
*The pathogenesis of HGA causes immunosuppression and thus fatality may be attributed to opportunistic pathogens. | |||
===Transmission=== | |||
*''Ehrlichia'' are transported between cells through the host cell [[filopodia]] during initial stages of infection, whereas, in the final stages of infection the pathogen ruptures the host cell membrane.<ref>{{cite journal |author=Thomas S, Popov VL, Walker DH |title=Exit Mechanisms of the Intracellular ''Bacterium Ehrlichia'' |journal=PLoS ONE |volume=5 |issue=12 |pages=e15775|year=2010|url=http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0015775 |doi=10.1371/journal.pone.0015775 |pmid=21187937|pmc=3004962|editor1-last=Kaushal |editor1-first=Deepak}}</ref> | |||
*Most of the symptoms of ehrlichiosis can likely be ascribed to the immune dysfunction that it causes. | |||
*Early in infection, production of [[TNF-alpha]], a cellular product that promotes [[inflammation]] and immune response, is suppressed. | |||
*Experiments in mouse models further supports this hypothesis, as mice lacking TNF-alpha I/II receptors are resistant to liver injury caused by ''ehrlichia'' infection. | |||
*Late in infection, however, production of this substance can be upregulated by 30 fold, which is likely responsible for the "[[toxic shock]]-like" syndrome seen in some severe cases of ehrlichiosis.<ref>{{cite journal|last=McBride|first=Jere W.|coauthors=Walker, David H.|title=Molecular and cellular pathobiology of Ehrlichia infection: targets for new therapeutics and immunomodulation strategies|journal=Expert Reviews in Molecular Medicine|date=31 January 2011|volume=13|doi=10.1017/S1462399410001730}}</ref> | |||
==References== | ==References== | ||
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[[Category:Disease]] | [[Category:Disease]] | ||
Latest revision as of 17:39, 18 September 2017
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Ehrlichiosis Microchapters |
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Diagnosis |
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Treatment |
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Case Studies |
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Ehrlichiosis pathophysiology On the Web |
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American Roentgen Ray Society Images of Ehrlichiosis pathophysiology |
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Risk calculators and risk factors for Ehrlichiosis pathophysiology |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Ilan Dock, B.S.
Overview
The pathophysiological process of ehrlichiosis begins with the inoculation of the disease from a tick vector. Following inoculation ehrlichiae and anaplasmosis enter the circulatory system in an attempt to infect a target cell. The infectious agents will then enter the cell via a receptor-mediated endocytosis. This particular endocytosis process is facilitated by a glycophoshoinositol anchored receptor. Both the ehrlichiae and anaplasma complete their reproduction process within the host cell's endosome. Infectious agents of both disease are then able to reprogram a host cell's defense mechanisms in order to silently proliferate.
Pathophysiology
Pathogenesis of Human Monocytotropic Ehrlichiosis
- E. chaffeensis enter into the mononuclear phagocytes.
- Phagolysosome fusion is inhibited while host genes are suppressed and induced to enable intracellular replication.
- Cytokines IL-12 and IL-18 are downregulated in THP-1 cells.
- Genes that are responsible for upregulation of apoptosis such as SNAP 23, Rab5A and STX16 are downregulated in correlation to the downregulation of IL-12 and IL-18.
- E. chaffeensis secretes an immunoreactive ankyrin protein (200kDa) into the host's nucleus in an attempt to manipulate the gene regulation of the host cell.
- Other methods of E. chaffeensis include inhibiting the signal transduction pathway and circumventing host cell defense mechanisms.
- Organ failure and other pathogenic manifestations resulting in complications or death is a result of immune mediated pathology.
Pathogenesis of Human Granulocytotropic Anaplasmosis
- A.phagocytophilum successfully resides within the host cells (PMN cells) cytoplasmic vacuoles.
- Apoptosis is suppressed due to the upregulation of bfl-1 and inhibiting anti-FAS. Both of which are responsible for inducing apoptosis within neutrophils.
- Host cell gene transcription is controlled through a secreted protein, AnkA, that travels into the host cell's nucleus.
- Research into the pathogensis of HGA has also shown upregulation of pro-inflammatory and IL-8 chemokines.
- The pathogenesis of HGA causes immunosuppression and thus fatality may be attributed to opportunistic pathogens.
Transmission
- Ehrlichia are transported between cells through the host cell filopodia during initial stages of infection, whereas, in the final stages of infection the pathogen ruptures the host cell membrane.[1]
- Most of the symptoms of ehrlichiosis can likely be ascribed to the immune dysfunction that it causes.
- Early in infection, production of TNF-alpha, a cellular product that promotes inflammation and immune response, is suppressed.
- Experiments in mouse models further supports this hypothesis, as mice lacking TNF-alpha I/II receptors are resistant to liver injury caused by ehrlichia infection.
- Late in infection, however, production of this substance can be upregulated by 30 fold, which is likely responsible for the "toxic shock-like" syndrome seen in some severe cases of ehrlichiosis.[2]
References
- ↑ Thomas S, Popov VL, Walker DH (2010). Kaushal, Deepak, ed. "Exit Mechanisms of the Intracellular Bacterium Ehrlichia". PLoS ONE. 5 (12): e15775. doi:10.1371/journal.pone.0015775. PMC 3004962. PMID 21187937.
- ↑ McBride, Jere W. (31 January 2011). "Molecular and cellular pathobiology of Ehrlichia infection: targets for new therapeutics and immunomodulation strategies". Expert Reviews in Molecular Medicine. 13. doi:10.1017/S1462399410001730. Unknown parameter
|coauthors=ignored (help)