Amoebic liver abscess pathophysiology: Difference between revisions
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==Overview== | ==Overview== | ||
Ameoebic liver abscess is caused by a [[protozoan]] ''[[Entamoeba histolytica]]''. It is the most common extraintestinal manifestation of [[amoebiasis]]. | Ameoebic liver abscess is caused by a [[protozoan]] ''[[Entamoeba histolytica]]''. It is the most common extraintestinal manifestation of [[amoebiasis]]. The mode of transmission of ''[[Entamoeba histolytica]]'' include *[[fecal-oral route]] (ingestion of food and water contaminated with feces containing [[cysts]]), sexual transmission via [[oral-rectal route]] in [[homosexuals]], [[vector]] transmission via flies, cockroaches, and rodents. [[Hepatocyte]] programmed cell death induced by ''[[Entamoeba histolytica]]'' causes [[amoebic liver abscess]]. The [[infection]] is transmitted to [[liver]] by [[portal venous system]]. | ||
==Pathophysiology== | ==Pathophysiology== | ||
| Line 11: | Line 11: | ||
:*''[[Entamoeba histolytica]]'' (the [[pathogen]]) | :*''[[Entamoeba histolytica]]'' (the [[pathogen]]) | ||
:*''[[Entamoeba|Entamoeba dispar]]'' (a [[commensal]]) | :*''[[Entamoeba|Entamoeba dispar]]'' (a [[commensal]]) | ||
* | *The mode of transmission of ''[[Entamoeba histolytica]]'' include:<ref name="pmid22763633">{{cite journal| author=Fletcher SM, Stark D, Harkness J, Ellis J| title=Enteric protozoa in the developed world: a public health perspective. | journal=Clin Microbiol Rev | year= 2012 | volume= 25 | issue= 3 | pages= 420-49 | pmid=22763633 | doi=10.1128/CMR.05038-11 | pmc=3416492 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22763633 }} </ref><ref name="pmid12660071">{{cite journal| author=Stanley SL| title=Amoebiasis. | journal=Lancet | year= 2003 | volume= 361 | issue= 9362 | pages= 1025-34 | pmid=12660071 | doi=10.1016/S0140-6736(03)12830-9 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12660071 }} </ref> | ||
:*Fecal-oral route (ingestion of food and water contaminated with feces containing [[cysts]]) | :*[[Fecal-oral route]] (ingestion of food and water contaminated with feces containing [[cysts]]) | ||
:*Sexual transmission via oral-rectal route in homosexuals | :*Sexual transmission via [[oral-rectal route]] in [[homosexuals]] | ||
:*Vector transmission via flies, cockroaches, and rodents. | :*[[Vector]] transmission via flies, cockroaches, and rodents. | ||
*[[Hepatocyte]] programmed cell death induced by ''[[Entamoeba histolytica]]'' causes amoebic liver abscess. | *[[Hepatocyte]] programmed cell death induced by ''[[Entamoeba histolytica]]'' causes [[amoebic liver abscess]]. | ||
*The [[infection]] is transmitted to [[liver]] by [[portal venous system]].<ref name="pmid473308">{{cite journal |vauthors=Aikat BK, Bhusnurmath SR, Pal AK, Chhuttani PN, Datta DV |title=The pathology and pathogenesis of fatal hepatic amoebiasis--A study based on 79 autopsy cases |journal=Trans. R. Soc. Trop. Med. Hyg. |volume=73 |issue=2 |pages=188–92 |year=1979 |pmid=473308 |doi= |url=}}</ref> | *The [[infection]] is transmitted to [[liver]] by [[portal venous system]].<ref name="pmid473308">{{cite journal |vauthors=Aikat BK, Bhusnurmath SR, Pal AK, Chhuttani PN, Datta DV |title=The pathology and pathogenesis of fatal hepatic amoebiasis--A study based on 79 autopsy cases |journal=Trans. R. Soc. Trop. Med. Hyg. |volume=73 |issue=2 |pages=188–92 |year=1979 |pmid=473308 |doi= |url=}}</ref> | ||
*Clinical syndromes associated with ''[[Entamoeba histolytica]]'' [[infection]] | *Clinical syndromes associated with ''[[Entamoeba histolytica]]'' [[infection]] | ||
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Yamuna Kondapally, M.B.B.S[2]
Overview
Ameoebic liver abscess is caused by a protozoan Entamoeba histolytica. It is the most common extraintestinal manifestation of amoebiasis. The mode of transmission of Entamoeba histolytica include *fecal-oral route (ingestion of food and water contaminated with feces containing cysts), sexual transmission via oral-rectal route in homosexuals, vector transmission via flies, cockroaches, and rodents. Hepatocyte programmed cell death induced by Entamoeba histolytica causes amoebic liver abscess. The infection is transmitted to liver by portal venous system.
Pathophysiology
- Amoebic liver abscess is the most common extraintestinal manifestation of amoebiasis.
- There are two genetically different species of entamoeba.[1] They are
- The mode of transmission of Entamoeba histolytica include:[2][3]
- Fecal-oral route (ingestion of food and water contaminated with feces containing cysts)
- Sexual transmission via oral-rectal route in homosexuals
- Vector transmission via flies, cockroaches, and rodents.
- Hepatocyte programmed cell death induced by Entamoeba histolytica causes amoebic liver abscess.
- The infection is transmitted to liver by portal venous system.[4]
- Clinical syndromes associated with Entamoeba histolytica infection
| Entamoeba histolytica | |||||||||||||||||||||||||||||||||||||||||||||||
| Intestinal amoebiasis •Asymptomatic cyst passers •Acute amoebic colitis - Mucosal disease - Transmural disease - Ulcerative postdysentric colitis *Appendicitis *Amoeboma *Amoebic stricture | Extra intestinal amoebiasis *Amoebic Liver abscess *Perforation and peritonitis *Pleuropulmonary amoebiasis *Amoebic pericarditis *Cutaneous Amoebiasis | ||||||||||||||||||||||||||||||||||||||||||||||
Pathogenesis
- After ingestion of contaminated food and water, Entamoeba histolytica trophozoites adhere to epithelial cells of colon, through the galactose/N-acetylgalactosamine specific lectin.[5]
- After adhesion, the parasite releases cysteine proteinases which digest extracellular matrix proteins. This facilitate trophozoite invasion into submucosal tissue through amoebapore leading to activation of amoebic virulence programme.[6][7]
- The extracellular amoebic cysteine proteinase converts pIL-1β (precursor interleukin 1β) to active IL-1β. The chemokines and cytokines released from epithelial cells attract macrophages and neutrophils to the site of infection.[8]
- Neutrophils transmigrating to the epithelial surface facilitate E histolytica invasion by creating channels. Cysteine proteinases digest extracellular matrix protein, causing epithelial cells to break from the villi, which also aid in the parasite's direct invasion into submucosal tissues.[9]
- The mediators released by the neutrophils cause more damage to adjacent intestinal epithelial cells.[10]
- The trophozoites penetrate the mucosa, submucosal tissues and even into the portal circulation where they encounter additional host defenses, including complement system.
- E histolytica are covered by highly glycosylated and phosphorylated lipophosphoglycan which may serve as a physical barrier to complement components. The amoebic Gal/GalNAc lectin has a region with antigenic crossreactivity with CD59 which protect trophozoites against lysis.[11]
- The cysteine proteinases cleave and inactivate the anaphylatoxins C3a and C5a along with human IgA and IgG which provides further defence against host immune response.[12][13]
- The trophozoites which enter the liver through portal circulations leading to apoptosis of liver cells and abscess formation.
- Stages of abscess formation include:
- Acute inflammation
- Granuloma formation
- Necrosis with necrotic abscess or periportal fibrosis
Variants of amoebic liver abscesses
- Solitary lesions (30%-70%) are more common amoebic liver abscesses and most commonly seen in right lobe of the liver.
- The right hepatic lobule is most commonly effected due to portal circulatory system of the right colon.
| Multiple liver abscesses | Left lobe abscess | Compression lesions | Extension of the abscess |
|---|---|---|---|
|
Aspiration + anti-amoebic drugs |
Bilateral pedal edema Ascites Visible veins on anterior and posterior abdominal wall Symptoms disappear after aspiration of abscess |
|
Gross pathology
- The amoebic liver abscesses are well circumscribed regions which contain necrotic material (dead hepatocytes, liquefied cells and cellular debris) and the surrounding fibrinous border.
- The adjacent liver parenchyma is usually normal.
- The abscesses are single or multiple.
- The abscess cavity may be filled with chocolate colored pasty material (anchovy sauce-like).
Microscopic pathology
- Multiple neutrophilic abscess with areas of necrosis are seen in the liver parencyma.
- A rim of connective tissue, with few inflammatory cells and amoebic trophozoites are clustered in the fibrin at the junction of viable and necrotic tissue.
References
- ↑ Gonin P, Trudel L (2003). "Detection and differentiation of Entamoeba histolytica and Entamoeba dispar isolates in clinical samples by PCR and enzyme-linked immunosorbent assay". J Clin Microbiol. 41 (1): 237–41. PMC 149615. PMID 12517854.
- ↑ Fletcher SM, Stark D, Harkness J, Ellis J (2012). "Enteric protozoa in the developed world: a public health perspective". Clin Microbiol Rev. 25 (3): 420–49. doi:10.1128/CMR.05038-11. PMC 3416492. PMID 22763633.
- ↑ Stanley SL (2003). "Amoebiasis". Lancet. 361 (9362): 1025–34. doi:10.1016/S0140-6736(03)12830-9. PMID 12660071.
- ↑ Aikat BK, Bhusnurmath SR, Pal AK, Chhuttani PN, Datta DV (1979). "The pathology and pathogenesis of fatal hepatic amoebiasis--A study based on 79 autopsy cases". Trans. R. Soc. Trop. Med. Hyg. 73 (2): 188–92. PMID 473308.
- ↑ Mann BJ (2002). "Structure and function of the Entamoeba histolytica Gal/GalNAc lectin". Int Rev Cytol. 216: 59–80. PMID 12049210.
- ↑ Leippe M, Andrä J, Nickel R, Tannich E, Müller-Eberhard HJ (1994). "Amoebapores, a family of membranolytic peptides from cytoplasmic granules of Entamoeba histolytica: isolation, primary structure, and pore formation in bacterial cytoplasmic membranes". Mol Microbiol. 14 (5): 895–904. PMID 7715451.
- ↑ Berninghausen O, Leippe M (1997). "Necrosis versus apoptosis as the mechanism of target cell death induced by Entamoeba histolytica". Infect Immun. 65 (9): 3615–21. PMC 175514. PMID 9284127.
- ↑ Seydel KB, Li E, Swanson PE, Stanley SL (1997). "Human intestinal epithelial cells produce proinflammatory cytokines in response to infection in a SCID mouse-human intestinal xenograft model of amebiasis". Infect Immun. 65 (5): 1631–9. PMC 175187. PMID 9125540.
- ↑ Que X, Reed SL (2000). "Cysteine proteinases and the pathogenesis of amebiasis". Clin Microbiol Rev. 13 (2): 196–206. PMC 100150. PMID 10755997.
- ↑ Salata RA, Pearson RD, Ravdin JI (1985). "Interaction of human leukocytes and Entamoeba histolytica. Killing of virulent amebae by the activated macrophage". J Clin Invest. 76 (2): 491–9. doi:10.1172/JCI111998. PMC 423849. PMID 2863284.
- ↑ Braga LL, Ninomiya H, McCoy JJ, Eacker S, Wiedmer T, Pham C; et al. (1992). "Inhibition of the complement membrane attack complex by the galactose-specific adhesion of Entamoeba histolytica". J Clin Invest. 90 (3): 1131–7. doi:10.1172/JCI115931. PMC 329975. PMID 1381719.
- ↑ Kelsall BL, Ravdin JI (1993). "Degradation of human IgA by Entamoeba histolytica". J Infect Dis. 168 (5): 1319–22. PMID 8228372.
- ↑ Reed SL, Keene WE, McKerrow JH, Gigli I (1989). "Cleavage of C3 by a neutral cysteine proteinase of Entamoeba histolytica". J Immunol. 143 (1): 189–95. PMID 2543700.