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PubMed1998

Secretory immune response in patients with intestinal amoebiasis.

The secretory immune response in saliva from intestinal amoebiasis patients against antigens obtained from Entamoeba histolytica membranes was studied. Western blot analysis indicated that patient saliva contains secretory IgA antibodies against antigens with molecular masses ranging from 170 to 24 kDa, some of which were also recognized by saliva from healthy subjects. However, antigens of 170, 125, 46 and 37 kDa are recognized more frequently (> 90%) by the secretory IgA from patients with intestinal amoebiasis than by that from healthy subjects (< 10%).

Animals↗
PubMed2003

Prospect for an Entamoeba histolytica Gal-lectin-based vaccine.

Entamoeba histolytica is the aetiological agent of invasive amoebiasis, the third leading parasitic cause of mortality in the world. The disease can be easily cured by chemotherapy; however, prevention, mainly in the form of vaccination, could greatly decrease the incidence of the disease, and possibly help in its eradication. The parasite's surface galactose and N-acetyl-d-galactosamine-inhibitable adherence lectin (Gal-lectin) is highly antigenic and is the most promising subunit vaccine candidate. We have generated a Gal-lectin-based DNA vaccine and tested its immunogenicity in mice. Although further optimization will probably be required, this vaccine could help in the generation of an amoebiasis DNA vaccine for use in humans.

Animals↗
PubMed2003

Regulatory effects of IL-12 and IL-18 on Onchocerca volvulus- and Entamoeba histolytica-specific cellular reactivity and cytokine profiles.

In the present study, the cytokines interleukin (IL)-12 and IL-18 were evaluated for their capacity to modulate and to re-direct in vitro parasite antigen-specific cellular responsiveness in patients exposed to Onchocerca volvulus and Entamoeba histolytica infection. We found that IL-18 was highly capable of reducing parasite antigen-induced IL-10 production by PBMC. In contrast, addition or neutralization of IL-12, also in combination with IL-18 and the interferon-gamma-inducible chemokine IP-10 did not affect IL-10 production. Interestingly, the highest IL-10 levels were measured when IL-18 and IP-10 were both neutralized. Although having no effect on IL-10, IL-12 strongly promoted spontaneous and parasite antigen-driven IFN-gamma production by PBMC, whereas IL-18 was only moderately affecting IFN-gamma release by PBMC re-stimulated with E. histolytica- or O. volvulus-specific antigens. Both IL-12 and IL-18 diminished the cellular production of IL-13, and a synergistic effect was observed when the cytokines were combined. Likewise, neutralization of IL-12 enhanced Entamoeba and Onchocerca antigen-driven IL-13 production, but no further increase of IL-13 was observed, when anti-IL-12 and anti-IL-18 were used together. This study disclosed that IL-18 will significantly down-regulate parasite-specific IL-10 production, whereas IL-12 induced IFN-gamma and inhibited IL-13 production by PBMC from humans exposed to O. volvulus and E. histolytica. Such selective immune-regulatory capacity of IL-12 and IL-18 may comprise an important tool to re-direct polarized cytokine responses towards a balanced Th1/Th2 cytokine profile, which may prevent pathology and promote immunity against helminth and protozoan parasite infections.

Adolescent↗
PubMed2002

Differences between the large and small intestine in the immunodominant amoebic proteins recognized by IgG and IgA antibodies in BALB/c mice.

We have previously reported that there are differences in the number of predominant amoebic antigens recognized by serum and small intestinal antibodies induced after local and systemic immunization with glutarldehyde-fixed Entamoeba histolytica trophozoites (GFT) in BALB/c mice, by an immunoblot analysis. Moreover, by enzyme-linked immunosorbent assay (ELISA) analysis, we found differences in the antiamoebic antibody isotype patterns elicited at the large and small intestines. To further characterize the antiamoebic immune response induced in BALB/c mice, after local (oral and rectal) and systemic (intraperitoneal and intramuscular) immunization with GFT, we performed an immunoblot analysis of the amoebic proteins predominantly recognized by immunoglobulins (Ig)G, IgA and IgM in the serum and in the small and large intestines. The present work shows differences between the large and small intestine in the IgG- and IgA-antibody recognition pattern of amoebic proteins, thus confirming and extending our previous findings supporting the compartmentalization of the intestinal immune response. Furthermore, our reported observation that there are differences in the amoebic proteins predominantly recognized by antibodies of different isotypes was extended to the intestines, as some proteins with relative molecular weights of 24-25, 66, 140 kDa are strongly recognized by IgG but not by other antibody isotypes.

Animals↗
PubMed2004

Parasite-specific antibody and cytokine profiles in newborns from Plasmodium falciparum and Entamoeba histolytica/dispar-infected mothers.

Passage of parasites and their antigens across the placenta occurs with metazoan as well as protozoan parasites, and this study addressed to which extent exposure to and infection of mothers with Plasmodium spp. and Entamoeba histolytica/dispar has sensitized their offspring for parasite-specific immune responses. While at delivery none of the mothers presented with an acute malaria attack, 42% were seropositive for P. falciparum. In half of the mothers cysts of E. histolytica/dispar were detected in stool specimen, 51% of them were found seropositive for E. histolytica, and E. histolytica-specific immunoglobulin A (IgA) responses were detected in neonates of seropositive mothers as well. Umbilical cord blood cells (UCBC) from neonates, when activated with the mitogen phytohaemagglutinine (PHA) and bacterial streptolysin O (SL-O), released significantly less interferon (IFN)-gamma, interleukin (IL)-10 and tumor necrosis factor (TNF)-alpha into cell culture supernatants than peripheral blood cells (PBMC) of mothers. In response to Plasmodium- and Entamoeba-specific antigens UCBC and PBMC produced equal amounts of IL-1beta, TNF-alpha, IFN-gamma and IL-5, but PBMC from mothers secreted significantly more IL-10. Parasite-specific production of inflammatory and Th(1)- and Th(2)-type cytokines was similar in newborns of Plasmodium and Entamoeba seropositive and seronegative mothers. In summary, repeated exposure and subclinical infection of mothers with E. histolytica or P. falciparum will suffice to prime in utero their children for inflammatory and both Th(1)- and Th(2)-type cytokine responses, and such broad and mixed cytokine spectrum may be of advantage upon secondary parasite challenge in later life.

Adult↗
PubMed1999

Purification and biochemical characterization of a novel cysteine protease of Entamoeba histolytica.

Cysteine proteases are important virulence factors of Entamoeba histolytica, the causative agent of amoebiasis. A novel cysteine protease from parasite extracts was purified 15-fold by a procedure including concanavalin A-Sepharose, hydroxylapatite and DEAE-Sepharose chromatography. The purification resulted in the obtainment of an homogeneous protein with a molecular mass of 66 kDa on native PAGE. In 10% SDS/PAGE, three bands of 60, 54 and 50 kDa were evident. Each of the three specific mouse antisera raised against these proteins showed cross-reactivity with the three bands obtained from the purified eluate. The N-terminal sequencing of the first 10 amino acids from the three proteins showed 100% identity. These results support the hypothesis of a common precursor for the 60, 54 and 50-kDa proteins. Protease activity of the purified enzyme was demonstrated by electrophoresis in a gelatine-acrylamide copolymerized gel. Its activity was quantified by cleaving a synthetic fluorogenic peptide substrate such as N-carbobenzyloxy-arginyl-arginyl-7-amido-4-methylcoumarin. The optimum pH for the protease activity was 6.5; however, enzymatic activity was observed between pH 5 and pH 7.5. Typical of cysteine proteases, the enzyme was inhibited by 4-[(2S, 3S)-carboxyoxiran-2-ylcarbonyl-L-leucylamido]butylg uanidine and iodoacetamide, and activated by free sulfhydryl groups. The cellular location of the enzyme was examined on trophozoites before and after contact with red blood cells using indirect immunofluorescence and cellular fractionation. The 60-kDa cysteine protease translocated to the amoebic surface upon the interaction of trophozoites with red blood cells. This result provided evidence for participation of the 60-kDa protease in erythrophagocytosis.

Amino Acid Sequence↗
PubMed2003

Emphysematous pyelonephritis and renal amoebiasis in a patient with diabetes mellitus.

Emphysematous pyelonephritis is an uncommon and life-threatening infection of the kidney that is characterized by gas formation within or around the kidney and is associated with diabetes mellitus and urinary tract infection. Amoebiasis is a protozoal infection caused by Entamoeba histolytica. In its invasive forms, the disease is characterized by visceral abscess formations. We present a case of concomitant emphysematous pyelonephritis and renal amoebiasis in a 42-year-old female with uncontrolled diabetes mellitus. The patient did not respond well to initial supportive treatment and antibiotherapy. Therefore, nephrectomy was performed. She did extremely well after the operation and was discharged with antidiabetics and antibiotics.

Adult↗
PubMed1999

New insights into the role of the cytoskeleton in phagocytosis of Entamoeba histolytica.

Entamoeba histolytica, a human parasite, crosses the natural barriers of the intestine and, in turn, spreads into the deeper organs, resulting in amoebiasis. The motility of the parasite and its ability to lyse or phagocytose human cells facilitates passage of the amoeba through the intestinal epithelium. Little is known about the uptake of material by this parasite; nevertheless, the cytoskeleton is believed to play a role in phagocytosis. Myosin IB, an actin-binding protein, localizes to the phagocytic cup and, with time, surrounds the internalized phagosome itself. The role of unconventional myosins in phagocytosis has also been demonstrated in other cell types, suggesting that this molecular mechanism is a common denominator in phagocytic events. Here, we summarize the emerging view of the role of unconventional myosins as well as other cytoskeleton-associated proteins in pseudopod formation at early stages of phagocytosis and during the late step of this process in E. histolytica.

Animals↗
PubMed2000

Caspase 3-dependent killing of host cells by the parasite Entamoeba histolytica.

The parasite Entamoeba histolytica is named for its ability to lyse host tissues. To determine the factors responsible, we have initiated an examination of the contribution of parasite virulence factors and host caspases to cellular destruction by the parasite. Amoebic colitis in C3H/HeJ mice was associated with extensive host apoptosis at sites of E. histolytica invasion. In vitro studies of E. histolytica-Jurkat T-cell interactions demonstrated that apoptosis required contact via the amoebic Gal/GalNAc lectin, but was unaffected by 75% inhibition of the amoebic cysteine proteinases. Parasite-induced DNA fragmentation was unaffected in caspase 8-deficient Jurkat cells treated with the caspase 9 inhibitor Ac-LEHD-fmk. In contrast, caspase 3-like activity was observed within minutes of E. histolytica contact and the caspase 3 inhibitor Ac-DEVD-CHO blocked Jurkat T cell death, as measured by both DNA fragmentation and 51Cr release. These data demonstrate rapid parasite-induced activation of caspase 3-like caspases, independent of the upstream caspases 8 and 9, which is required for host cell death.

Animals↗
PubMed1989

[A new experimental model of cecal amebiasis in rats].

The young rat was used as an experimental model of caecal amebiasis by implanting, without injury of the caecum, a suspension of E. histolytica trophozoites gnotoxenic strain Rahman of high virulence. The degree of pathogenicity is demonstrated by the macroscopic aspect of caecum, by the density of trophozoites and by an anatomopathologic examination. As a correlation exits between all these macroscopic parameters and histology, a degree of illness is fixed which include several macro- and microscopic criteria. This model enables to observe the different phases of cicatrization and of recovering of young rats and so to appreciate the activity of antiamebic agents.

Amebiasis↗
PubMed1990

[Effects of Saccharomyces boulardii yeast on trophozoites of Entamoeba histolytica in vitro and in cecal amebiasis in young rats].

Lyophilized and rehydrated Saccharomyces boulardii yeasts were administered to young rats previously inoculated into the cecum with Entamoeba histolytica. The numbers of diseased young rats and the severity of the infection, assessed from the appearance of the cecum and its content of mucus and amebae, were significantly reduced by the treatment. The lesions observed resembled those seen in the untreated controls, although healing was faster in the treated animals. Saccharomyces boulardii had no intrinsic amebicidal action in vitro.

Animals↗
PubMed1994

[Gnathostomiasis after a stay in Thailand].

During a 4-week holiday in Thailand a 13-year-old boy from Germany briefly fell ill with diarrhoea without blood-tinged stools and fever. 5 months later oedematous, reddish swellings occurred, at first on the right upper arm, later over the right side of the chest. Especially at night these swellings were associated with severe local and generalized itching. Bilaterally the axillary lymph-nodes were hard and slightly enlarged. There was a marked eosinophilia of 56%, the white count was 22,700/microliters and the serum level of IgE was raised to 1777 IU/ml. No worm eggs or larvae were found in the stool. Enzyme-linked immunosorbent assay, using larvae of Gnathostoma spinigerum as antigen, demonstrated antibodies against this nematode. Gnathostomiasis having been diagnosed treatment was started with albendazole (200 mg twice daily for 21 days), after which the boy was symptom free. After 2 months the eosinophilia had regressed to 10%, the white cell count was normal and the antibody titre had fallen.

Adolescent↗
PubMed1988

[The importance of Entamoeba histolytica in persons returning from the tropics].

Stools from 1000 travellers returning from the tropics were examined for intestinal parasites. The most frequently isolated intestinal pathogens were Giardia lamblia (5%) and E. histolytica (3.6%). For 21 out of 36 E. histolytica isolates iso-enzyme differentiation by starch-gel electrophoresis was possible, yielding a pathogenic pattern in four. This finding correlated closely with clinical symptoms and positive serology, while E. histolytica with non-pathogenic zymodeme should not be considered as a cause of diarrhoea.

Adult↗
PubMed1988

[Gastrointestinal findings in HIV infection. Clinical aspects, microbiological findings and endoscopic picture].

Among 200 hospitalized patients treated for HIV infections there were 98 with gastrointestinal symptoms, independent of the stage of the disease. Only 22 had abnormal stool findings. But histological examination and culture of endoscopically obtained biopsies revealed opportunistic infection in 62, of whom 28 had a cytomegalovirus infection. Mycobacterium avium-intracellulare was found in the gastrointestinal mucosa of 25 patients, but its clinical significance is unclear. In 33 of the 98 patients previously classified as positive for HIV or AIDS-related complex, endoscopic demonstration of an opportunistic infection required amendment of their HIV stage. In over 60% endoscopy revealed mucosal changes. A distinction from Crohn's disease or ulcerative colitis could only be made by histology or exclusion of the causative microorganism. Demonstration of the causative microorganism from the biopsy is thus essential in patients with gastrointestinal symptoms, because specific treatment is in principle possible and successful for some opportunistic infections.

AIDS-Related Complex↗
PubMed1984

[Four kinds of parasites in an 8-year-old boy. Therapeutic effects of praziquantel against Fasciola hepatica].

An 8-year-old Turkish boy had recurrent abdominal colics associated with marked eosinophilia. Four different kinds of parasites were isolated from stool and duodenal juice: Fasciola hepatica, Entamoeba histolytica, Ascaris lumbricoides and Lamblia intestinalis. Conventional drugs were successful in treating the latter three parasites. But because of problems connected with the treatment of F. hepatica, praziquantel was administered, 15 mg/kg five times daily for 5 days, with curative results. This is the first published successful treatment of Fasciola hepatica with this drug in Europe.

Ascariasis↗
PubMed1983

[Intestinal protozoal infestation in persons with occupational sewage contact].

Intestinal protozoal infestation and antibodies against Entamoeba histolytica were determined in 614 employees of the Hamburg sewage works and compared with control groups without occupational sewage contact. The protozoal infection rate was significantly higher in sewer-men than in control persons. There was a positive correlation between the duration of exposure to sewage and the frequency of intestinal protozoal infestation. The risk of infection by sewage was higher than by a short journey to tropical or subtropical countries. Immunodiagnostic results showed no significant differences of invasive activity of E. histolytica between both investigated groups. On the basis of parasitological results classification of amoebiasis and giardiasis as occupational diseases in exposed persons is recommended.

Entamoeba histolytica↗
PubMed1999

Multifocal omental mesenteric inflammatory pseudotumor (plasma cell granuloma).

Inflammatory pseudotumor (IP) is an uncommon benign tumor during childhood. The most common location is lung, and sporadic cases of IP with extrapulmonary involvement such as liver and abdomen are reported. However, the IP among the reported cases have appeared as solitary masses. A multifocal IP in a 14-year-old girl presumed to result following an Entamoeba histolytica infestation is reported.

Adolescent↗
PubMed1981

Sexual transmission of enteric protozoa and helminths in a venereal-disease-clinic population.

We examined the prevalence of enteric protozoan and helminthic infections and the associations between infection and gender, sexual preference, and sexual practices in 180 consecutive patients at a venereal-disease clinic. Of 163 men, 29 were infected with one or more enteric parasites. None of the 17 women had an enteric infection. The prevalence of infections with Entamoeba histolytica or Giardia lamblia (or both) was 21.5 per cent in homosexual men, 6.2 per cent in bisexual men, and 0 in heterosexual men. There were significant associations between oral-anal sex and infection with E. histolytica (P less than 0.01) or with helminths (P less than 0.05). Homosexuality and oral-anal sex were the most important risk factors in E. histolytica, G. lamblia, and helminthic infections. We conclude the "hyperendemic" enteric protozoan infection rates in homosexual men are related to three factors: the original endemic level in the general population; the prevalence of sexual acts that facilitate transmission; and the frequency of exposure to an infected person.

Entamoebiasis↗