Testosterone affects type I/type II interferon response of neutrophils during hepatic amebiasis

Differences in immune response between men and women may influence the outcome of infectious diseases. Intestinal infection with Entamoeba histolytica leads to hepatic amebiasis, which is more common in males. Previously, we reported that innate immune cells contribute to liver damage in males in the murine model for hepatic amebiasis. Here, we focused on the influences of sex and androgens on neutrophils in particular. Infection associated with neutrophil accumulation in the liver was higher in male than in female mice and further increased after testosterone treatment in both sexes. Compared with female neutrophils, male neutrophils exhibit a more immature and less activated status, as evidenced by a lower proinflammatory N1-like phenotype and deconvolution, decreased gene expression of type I and type II interferon stimulated genes (ISGs) as well as downregulation of signaling pathways related to neutrophil activation. Neutrophils from females showed higher protein expression of the type I ISG viperin/RSAD2 during infection, which decreased by testosterone substitution. Moreover, ex vivo stimulation of human neutrophils revealed lower production of RSAD2 in neutrophils from men compared with women. These findings indicate that sex-specific effects on neutrophil physiology associated with maturation and type I IFN responsiveness might be important in the outcome of hepatic amebiasis.

Travel history can make the difference

Entamoeba histolytica infections are rare in developed countries such as Belgium. A 53-year-old female patient presented with 10 days of fever and mild persisting pain in the right hypochondriac despite 6 days of antibiotic therapy. The anamnesis further revealed that the patient was born in Colombia and visits her native country on a regular basis. An abdominal CT-scan demonstrated a large hepatic abscess of 10×8 cm. The diagnosis of Entamoeba histolytica- infection was confirmed with real-time PCR (RT-PCR) from the aspirated material of the abscess. Remarkably, a half year ago, this patient also presented to the gastro-enterology consultation with intermittent rectal bleeding, loose stools and abdominal discomfort. Rectosigmoidoscopy at that time showed sigmoiddiverticulosis and biopsies were taken. RT-PCR on this material was performed during this second episode and was positive for E. histolytica, confirming an episode of amoebic colitis a half year prior to the discovery of the liver abscess.

Amebic Liver abscess Complicated by Inferior Vena Cava Thrombosis: A Case Report

Amebic liver abscess is the most common extraintestinal manifestation of infection with Entamoeba histolytica. It is a common disease, especially in endemic areas, but it is a rare cause of inferior vena cava (IVC) obstruction, with only a few cases appearing in the literature. The authors describe a case of amebic liver abscess in a patient who developed a rare vascular complication of inferior vena cava thrombosis. The case responded to conservative treatment and radiological intervention.

Enhanced pro-inflammatory chemokine/cytokine response triggered by pathogenic Entamoeba histolytica : basis of invasive disease

The virulence of Entamoeba histolytica is governed by adhesion/colonization in the gut which is mediated by a galactose specific lectin. Two morphologically identical but distinct species i.e. pathogenic E. histolytica and non-pathogenic E. dispar, can be differentiated by distinct epitopes in the lectin. Both species bind to colonic epithelial cells, but only E. histolytica infection induces an inflammatory response and subsequent pathogenesis. Thus, comparing the responses of the intestinal cells to pathogenic and non-pathogenic lectins is a point of interest. The pathogenic lectin causes cytolysis of epithelial and immune-competent cells. Our data (both qualitative and mRNA quantitation) indicate that the epithelial cells responded to E. histolytica lectin with an increased expression of pro-inflammatory IL-2, IL-6, IL-8, MIP-1alpha, MCP-1, RANTES, GROalpha and GMCSF as compared to E. dispar lectin. The pathogenic LCM induced a significant increase in intracellular calcium concentration, proliferative response and chemotaxis of lymphocytes from ALA patients as compared to non-pathogenic LCM. High RANTES and IL-6 were induced in patients' lymphocytes by pathogenic LCM, along with their receptors CCR5 and CD126 as compared to NP-LCM. The local release of such a complex network of cytokines/chemokines could explain the histopathology of E. histolytica infection. The comparative low levels of these chemokines/pro-inflammatory cytokines and high levels of anti-inflammatory IL-10 in response to non-pathogenic E. dispar could explain the absence of an acute inflammatory response and the disease process. The cytokines and chemokines may provide a mechanism for initiation, amplification or containment of inflammation during disease state.

Experimental hepatic amoebiasis and its application to chemotherapeutic studies

Induction of hepatic amoebiasis with two strains of Entamoeba histolytica has been attempted by direct inoculation of trophozoites into the livers of rats, hamsters, and guinea-pigs, and by intravenous injection into guinea-pigs. A high incidence of amoebic abscesses was obtained in hamsters. Rats and guinea-pigs were relatively less susceptible. The two strains of Entamoeba histolytica differed in virulence. Serial liver passage increased their virulence for the hamster liver, and also increased invasiveness to the rat caecum. The chemotherapeutic effects of chloroquine, emetine, and some anilides were determined. The procedure finally adopted was based on mean survival times of treated and untreated animals. Chloroquine and emetine were effective under conditions which greatly favoured the drugs, but the anilides showed little effect.

Amoebic liver abscess

Sonography is a major advance in the diagnosis of ALA. Identification of amoebic antigen in the pus is a specific immunodiagnostic test. Medical therapy with a single drug (metronidazole) is adequate in most instances. Routine needle aspiration or surgical drainage are not indicated. The abscess cavity may take up to 18 months for resolution and demonstration of such a lesion does not warrant repeated therapy unless clinical evidence of recurrence is present. Recurrences are rare. Clinical and laboratory evidences of poor prognosis are being identified, and may guide the treatment modality to be selected.

Pediatric liver cysts and abscesses

Cystic liver lesions in children pose diagnostic and therapeutic dilemmas. When discovered during evaluation of abdominal distension, the likely cause is benign hepatic cyst. Surgical intervention aimed at resection is highly curative. Echinococcal disease, usually distinguishable from nonparasitic cystic disease, is rare in children in the United States. Therapy is aimed at sterilization and complete excision of hydatid tissue. Cystic liver lesions in septic children represent liver abscesses, pyogenic or amebic, which are frequently fatal if not diagnosed early and treated appropriately. Ultrasonography and computed tomography have simplified the diagnosis and treatment of these diseases, but a high index of suspicion is required because the signs and symptoms of liver abscess in children are nonspecific.

Amoebic liver abscess in a bisexual man

A bisexual man who had not travelled outside the U.K. had an amoebic liver abscess. Although it is reported that Entamoeba histolytica is usually of a non-pathogenic type in homosexual men in the U.K., it is important to diagnose invasive amoebiasis in this high-risk group so that appropriate treatment can be given.

pH of amoebic liver pus

Amoebic liver pus has an acidic pH. Hence the pleural aspirate from an amoebic empyema due to rupture of an amoebic liver abscess has an acidic pH. In contrast, the pH of pleural aspirates from effusions and empyema of non-amoebic aetiology were noted to have an alkaline pH. The clinical significance of these observations is discussed.