Anatomicopathological Study of Vascular and Biliary Systems Using Cast Samples of Fasciola-infected Bovine Livers

Extracellular vesicles of the liver fluke Opisthorchis felineus stimulate the angiogenesis of human umbilical vein endothelial cells

The liver fluke Opisthorchis felineus is a clinically important food-borne parasite of humans. Infection with O. felineus in mammals is associated with liver morbidities such as periductal fibrosis, bile duct neoplasia, and chronic inflammation. Previously we have shown that excretory-secretory products (ESP) can stimulate the healing of skin wounds in mice, which may be due to stimulated angiogenesis and extracellular matrix remodeling. However, there are no studies analyzing the angiogenic character of O. felineus, and its effects on angiogenesis, vascularity, and vascular endothelium. The aim of this study was to evaluate the capacity of ESP and extracellular vesicles (EVs) of O. felineus to stimulate angiogenesis and the formation of pseudo-capillaries in vitro. We also aimed at the assessment of the angiogenesis during the infection in vivo, and estimation of the endothelial cell type abundances from heterogeneous bulk liver transcriptome between uninfected and infected animals with single-cell information. The study revealed significant alterations in vascularity in the hamster liver and significant involvement of portal endothelial cells at the transcriptome level. We also demonstrated that the ESP and EVs of O. felineus have the capacity to stimulate the formation of pseudo-capillaries in vitro. Both ESP and EVs appeared to have similar effects on all four parameters, increasing node formation and total master segments length, and significantly decreasing total isolated branches length and number of isolated segments of pseudo-capillaries. The liver flukes manipulate the host's angiogenic response, a fact that has been related to the pathogenesis caused by these parasites. Understanding these pathogenic mechanisms may uncover new therapeutic targets to relieve or prevent the most severe complications of opisthorchiasis.

Caracterização do imunofenótipo das células envolvidas no processo fibrótico de fígados bovinos cronicamente infectados por Fasciola hepatica

RESUMO A fasciolose é uma doença parasitária causada por trematódeo do gênero Fasciola sp., que pode ocasionar fibrose hepática. Objetivou-se caracterizar o imunofenótipo das células que participam da fibrogênese de fígados bovinos frente à infecção por F. hepatica. Foram utilizados fragmentos dos lobos direito e esquerdo de 74 fígados bovinos com fasciolose. Os fragmentos foram submetidos a processamento histológico, coloração com tricrômico de Masson e imuno-histoquímica. Utilizaram-se análise estatística descritiva e teste de correlação de Spearmann com 5% de probabilidade. Na classificação do grau de fibrose, observou-se prevalência do grau 1, com associação positiva e significativa entre o grau de fibrose e o lobo hepático esquerdo (ρ=0,41; P<0,0001). Os imunofenótipos observados foram células estreladas hepáticas (CEHs) no parênquima e miofibroblastos (MFs) no espaço porta (EP). Não foram encontrados fibroblastos. Não houve correlação significativa entre o grau de fibrose e a quantidade de CEH nos lobos hepáticos, direito e esquerdo. Verificou-se aumento do número de estruturas portais, bem como do número de camadas circundando cada estrutura no EP, contudo não houve influência de qualquer estrutura sobre o grau de fibrose hepática (P>0,05). Concluiu-se que as células CEH e os MFs participam da fibrogênese de fígados bovinos com fasciolose crônica.

The role of hepatic myofibroblasts in liver cirrhosis in fallow deer (Dama dama) naturally infected with giant liver fluke (Fascioloides magna)

Background

This paper describes liver cirrhosis in 35 fallow deer infected with the giant liver fluke, as well as the distribution, origin, and role of myofibroblasts in its development.

Results

In liver of infected deer, stripes of connective tissue are wound around groups of degenerated and regenerated liver lobuli. In the connective tissue, lymphocytes and macrophages which often contain parasite hematin are also present. The walls of the bile ducts are thickened, the epithelium multiplied with mucous metaplasia, and desquamated cells, parasite eggs and brown pigment are present in their lumen.

In the livers with cirrhosis, immunopositivity to α-SMA and desmin was observed in cells in portal and septal spaces, at the edge between fibrotic septa and the surrounding parenchyma and in perisinusoidal spaces. These cells vary in size, they are round, oval, spindle-shaped or irregular in shape, similar to vascular smooth muscle cells. The derangement of epithelial-mesenchymal interactions detected in chronic cholangiopathies is most probably the pro-fibrogenic mechanism in liver cirrhosis of fallow deer (Dama dama) infected with the giant liver fluke (Fascioloides magna).

Conclusion

Myofibroblasts, especially hepatic stellate cells (HSCs), play an important role in the synthesis of extracellular matrix components in the development of parasitic fibrosis and cirrhosis in the liver of fallow deer.

Angiogenesis and parasitic helminth-associated neovascularization

Successful metazoan parasitism, among many other factors, requires a supply of nutrients and the removal of waste products. There is a prerequisite for a parasite-defined vasculature. The angiogenic mechanism(s) involved presumably depend on the characteristics of the tissue- and vascular system-dwelling, parasitic helminths. Simplistically, 2 possibilities or a combination of both have been considered in this review. The multifactorial induction of parasitic helminth-associated neovascularization could arise through, either a host-, a parasite- or a host-/parasite-dependent, angiogenic switch. Most studies appear to support the first and third hypotheses, but evidence exists for the intrahepatic cestodeEchinococcus multilocularis, the free-living nematodeCaenorhabditis elegansand the intravascular trematodeSchistosoma mansonifor the second inference. In contrast, the nematode anti-coagulant protein NAPc2 from adultAncylostoma caninumis also an anti-angiogenic factor.

Mechanisms of liver fibrosis associated with experimental Fasciola hepatica infection: roles of Fas2 proteinase and hepatic stellate cell activation

We have evaluated the possible mechanisms of liver fibrosis caused by Fasciola hepatica in an animal model and in culture using immortalized human stellate cells. Liver biopsies of F. hepatica-infected rats were performed at wk 8 and 16. Serum-starved LX-2 cells, a human stellate cell line, were exposed to increasing concentrations of Fas2 antigen. The expression of key fibrosis-related genes was evaluated by qRT-PCR. There was a significant correlation between fibrogenic gene expression and both intensity and duration of infection. LX-2 cells exposed to Fas2 showed progressively increased expression of mRNAs for Collagen I, alpha-smooth muscle-actin, platelet-derived growth factor beta receptor, and tissue inhibitor of metalloproteinase II; inhibition of Fas2 cysteine proteinase activity by E-64 abrogated these increases, suggesting that the protease activity of Fas2 is involved in fibrogenic stimulation. In summary, F. hepatica infection is associated with up-regulation of mRNAs associated with hepatic fibrogenesis in vivo and in activated hepatic stellate cells.

Detection of antibodies against Fasciola hepatica in cirrhotic patients from Peru

The prevalence of Fasciola hepatica infection, in endemic countries, in patients with established cirrhosis is unknown. We hypothesized that, in endemic countries, the presence of fascioliasis may be detected in a serum pool of cirrhotic patients. Forty-four previously stored serum samples of patients with established liver cirrhosis, in the Hospital Nacional Cayetano Heredia in Lima, Peru, were collected from 1998 to 2003 and assessed for hepatitis B, C and fascioliasis antibodies (Fas2 ELISA). Hepatitis B surface antigen (HBsAg) was positive in 8.8% (n = 34), hepatitis B core antibody (anti-HBc) in 32.5% (n = 34), hepatitis C antibodies (anti-HCV) in 9.1% (n = 33), and 9.1% (n = 44) were Fas2 ELISA positive. This disease is an example of an emerging tropical infection which can be present in chronic liver diseases, requiring greater clinician awareness especially in endemic rural areas. Further clinical studies are warranted.