Selected Molecular Mechanisms Involved in the Parasite⁻Host System Hymenolepis diminuta⁻Rattus norvegicus.

The rat tapeworm Hymenolepis diminuta is a parasite of the small intestine of rodents (mainly mice and rats), and accidentally humans. It is classified as a non-invasive tapeworm due to the lack of hooks on the tapeworm's scolex, which could cause mechanical damage to host tissues. However, many studies have shown that metabolites secreted by H. diminuta interfere with the functioning of the host's gastrointestinal tract, causing an increase in salivary secretion, suppression of gastric acid secretion, and an increase in the trypsin activity in the duodenum chyme. Our work presents the biochemical and molecular mechanisms of a parasite-host interaction, including the influence on ion transport and host intestinal microflora, morphology and biochemical parameters of blood, secretion of antioxidant enzymes, expression of Toll-like receptors, mechanisms of immune response, as well as the expression and activity of cyclooxygenases. We emphasize the interrelations between the parasite and the host at the cellular level resulting from the direct impact of the parasite as well as host defense reactions that lead to changes in the host's tissues and organs.

Identification of immunogenic proteins of the cysticercoid of Hymenolepis diminuta.

BACKGROUND: A wide range of molecules are used by tapeworm metacestodes to establish successful infection in the hostile environment of the host. Reports indicating the proteins in the cestode-host interactions are limited predominantly to taeniids, with no previous data available for non-taeniid species. A non-taeniid, Hymenolepis diminuta, represents one of the most important model species in cestode biology and exhibits an exceptional developmental plasticity in its life-cycle, which involves two phylogenetically distant hosts, arthropod and vertebrate. RESULTS: We identified H. diminuta cysticercoid proteins that were recognized by sera of H. diminuta-infected rats using two-dimensional gel electrophoresis (2DE), 2D-immunoblotting, and LC-MS/MS mass spectrometry. Proteomic analysis of 42 antigenic spots revealed 70 proteins. The largest number belonged to structural proteins and to the heat-shock protein (HSP) family. These results show a number of the antigenic proteins of the cysticercoid stage, which were present already in the insect host prior to contact with the mammal host. These are the first parasite antigens that the mammal host encounters after the infection, therefore they may represent some of the molecules important in host-parasite interactions at the early stage of infection. CONCLUSIONS: These results could help in understanding how H. diminuta and other cestodes adapt to their diverse and complex parasitic life-cycles and show universal molecules used among diverse groups of cestodes to escape the host response to infection.

Hymenolepis diminuta: Effect of infection on ion transport in colon and blood picture of rats.

The aim of this study was to examine the effect of an infection with Hymenolepis diminuta on ion transport in an isolated colon and blood picture of rats. Fifty rats were orally infected with five cysticercoids of H. diminuta. The experimental groups of rats were assigned to four groups: group I - 8 days post-infection (dpi), group II - 16 dpi, group III - 40 dpi and group IV- 60 dpi. The control group comprised non-infected rats. The experiments consisted of measuring the transepithelial electrical potential difference (PD) and the transepithelial electrical resistance (R) of the rat colon under controlled conditions as well as during mechanical stimulation (MS) using a modified Ussing chamber. Ion transport was modified using inhibitors of the epithelial sodium channel (amiloride - AMI) and the epithelial chloride channel (bumetanide - BUME), and also using capsaicin (CAPSA), a substance which activates C-fibres. The experimental data presented in this study indicates that experimental hymenolepidosis inhibits sodium and chloride ion transport in the epithelium of the rat colon, with preserved tight junction continuity (except at 40 dpi) and a decreased mechanical sensitivity. The effect of capsaicin on ion transport in the rat colon was varied. In control rats it increased ionic current, and in H. diminuta-infected rats it did not cause any changes in PD. Blood picture in this study showed a statistically significantly lower red blood cells (RBC) count and haemoglobin (HGB) concentration in infected rats in comparison to non-infected. Red cell distribution width (RDW) values and platelet (PLT) count were negatively correlated with the duration of infection, whereas mean corpuscular volume (MCV) value was positively correlated. We did not observe leukocytosis during infection, and amongst the differential leukocyte counts eosinophils and basophils showed statistically significant lower values in infected rats in comparison to non-infected. Our results indicate that hymenolepidosis is associated with the activation of inflammatory mediators and stimulation of nervous fibres, which significantly affects the function of ion channels in the epithelium of the colon in the host. At the same time, a significant decrease in eosinophil count during infection suggests that such an infection did not trigger a strong immunological reaction in rats.

Intestinal permeability in Hymenolepis nana as reflected by non invasive lactulose/mannitol dual permeability test and its impaction on nutritional parameters of patients.

Assessment of Hymenolepis nana infection among 102 children and adults of both sexes (5-16 years) residing 2 Welfare Institutes (Giza and Cairo) showed a prevalence of 22.33%. The effect of H. nana on intestinal permeability and on nutritional parameters of patients was studied. A total of 46 subjects were divided into 2 groups: GI (20 H. nana patients) and GII (26 parasite-free control). Both groups were subjected to lactulose/mannitol dual permeability test, anthropometric study, estimation of vitamin B12 and folate levels in plasma and estimation of haemoglobin (HB)%, RBCs and WBCs counts and haematocrite value (HCT%) for anaemia. The H. nana patients showed significant higher percent (P = 0.04) of altered intestinal permeability versus controls denoting intestinal leakage, significant means lower levels of vitamin B12 (P = 0.01) and folate (P < 0.04) in blood plasma versus control denoting liability to vitamin B12 & folate deficiencies. Means value of HB%, RBC & WBC counts and HCT% showed generalized decrease but without significant difference in H. nana patients and control denoting anaemia liability. The percent of stunting (HAZ < or =2) and of wasting (WAZ < or =2) were higher among H. nana patients versus controls but without significant difference (P = 0.19 & P = 0.47 respectively).

Study of soluble adhesion molecules in some intestinal and tissue helminthes.

Soluble adhesion molecules namely soluble intercellular adhesion molecule-1 (sICAM-1) and soluble E-selectin (sELAM-1) were assayed in hydatid patients with or without complications. It was found that sICAM-1 was significantly increased in patients with hydatid cysts as compared to the control group. In lymphoedemic filariasis cases both sICAM-1 and sELAM-1 showed highly significant increase more than the control group. However, non of both soluble adhesion molecules were significantly elevated in patients with ascariasis, hymenolepiasis, heterophyiasis and strongyloidiasis as compared to controls. The results indicated that SICAM-1 & S ELAM-1 are useful markers for hydatidosis and filariasis, but not for ascariasis, hymenolepiasis, heterophyiasis and strongyloidiasis

Interactions between rat C-reactive protein and adult Hymenolepis diminuta.

Interactions between adult Hymenolepis diminuta and rat C-reactive protein (CRP) were investigated in vivo and in vitro. Using an ELISA technique, serum levels of CRP were monitored in rats infected with 100 cysticercoids. Although infection increased the level of this protein in the early stages of parasitization, the increase was not significant until 35 days post-infection (p.i.). Secondary infections did not enhance the response. When H. diminuta was cultured in the presence of CRP, reduced worm motility and opaque areas were observed and electron microscopical studies revealed shedding of microtriches and lysis of the tegument. Initially, damage was restricted to the strobila which correlated with the regional distribution of phosphorylcholine as visualized using immunofluorescence.

The diagnostic importance of species specific and cross-reactive components of Taenia solium, Echinococcus granulosus, and Hymenolepis nana.

Sera from patients infected with Taenia solium, Hymenolepis nana and Echinococcus granulosus were tested against homologous and heterologous parasite antigens using an ELISA assay, and a high degree of cross-reactivity was verified. To identify polypeptides responsible for this cross reactivity, the Enzyme Linked Immunoelectro Transfer Blot (EITB) was used. Sera from infected patients with T.solium, H.nana, and E.granulosus were assessed against crude, ammonium sulphate precipitated (TSASP), and lentil-lectin purified antigens of T.solium and crude antigens of H.nana and E.granulosus. Several bands, recognized by sera from patients with T.solium, H.nana, and E.granulosus infections, were common to either two or all three cestodes. Unique reactive bands in H.nana were noted at 49 and 66 K-Da and in E.granulosus at 17-21 K-Da and at 27-32 K-Da. In the crude cysticercosis extract, a specific non glycoprotein band was present at 61-67 K-Da in addiction to specific glycoprotein bands of 50, 42, 24, 21, 18, 14, and 13 K-Da. None of the sera from patients with H.nana or E.granulosus infection cross reacted with these seven glycoprotein bands considered specific for T.solium infection.

Specific antibodies in serum of patients with hydatidosis recognised by immunoblotting.

Hydatid fluids from sheep, goat, pig and man, after resolution by sodium dodecyl sulphate-polyacrylamide gel electrophoresis under reducing conditions, revealed at least 15 discrete polypeptide bands of 8-116 Kda. By ELISA, sera from all 20 cases of hydatidosis showed anti-hydatid antibody, but so did 11 (73%) of 15 sera samples from cysticercosis patients, eight (67%) of 12 sera from patients with other parasitic infections (amoebic liver abscess or hymenolepiasis) and one (4%) of 25 sera from healthy controls. Antibody to cysticercus antigen was found in 14 (93%) of 15 sera from cysticercosis patients, 17 (85%) of 20 sera from hydatid patients, six (50%) of 12 sera from patients with other parasitic infections and one (4%) of 25 sera from healthy controls. Sera from 17 (85%) of 20 hydatid patients, 11 (73%) of 15 cysticercosis patients and five (42%) of 12 patients with other parasitic infections had antibodies to both hydatid and cysticercus antigens. Sera from 20 surgically confirmed cases of hydatidosis reacted with 12 polypeptides of 8-116 Kda in Western immunoblot with hydatid antigens. Polypeptides of 16, 24, 38, 45 and 58 Kda were recognised by all hydatidosis sera but also by many sera from patients with other infections. However, polypeptides of 8 and 116 Kda were recognised by all hydatidosis sera but not by any sera from patients with cysticercosis, other parasitic infections or viral hepatitis, or from healthy controls. Thus, recognition of 8- and 116-Kda hydatid antigens by a patient's serum appears to be a specific test confirming a clinical diagnosis in an individual case of hydatidosis.

Serum protein profile of mice during infection with single and repeated doses of Hymenolepis nana eggs.

Significant alterations in serum protein of mice following Hymenolepis nana infection were observed. These changes were recorded as decrease in albumin, increase in gamma globulin and a temporary rise in alpha-1, alpha-2 and beta globulins. The decrease in albumin and increase in gamma globulin occurred as early as on 1st day after infection. The alpha-1 and alpha-2 globulins did not show definite profile during infection. The beta globulin predominantly increased till the day 20 post infection and thereafter generally decreased. Repeated infection did not enhance any further alterations in serum protein. There was no significant correlation between infection dose levels and serum protein changes.

Serum and antral gastrin levels in rats infected with intestinal parasites.

Serum and antral gastrin were measured in rats infected with either Trichinella spiralis or Hymenolepis diminuta as a step in testing the hypothesis that parasites change certain aspects of host physiology by altering gastrointestinal (GI) hormone levels or responses to GI hormones. Parasitism with T. spiralis was associated with inflammatory changes in the small bowel mucosa and with a significant increase in serum gastrin. Neither changes in hormone level nor inflammation were induced in tapeworm-infected rats. These results reveal the capacity of tissue penetrating parasites to alter the level of circulating gastrin. This finding coupled with considerable indirect evidence suggests that some of the pathologic changes induced in hosts by enteric parasites may be due to changes in functions that are regulated by GI hormones.

Haematological and immunological responses to the tapeworm hymenolepis diminuta in man.

Self-infections with the tapeworm Hymenolepis diminuta were carried out to study the haematological and immunological responses in man. Infection caused pronounced eosinophilia, an increase in plasma viscosity and the production of parasite-specific IgG and IgM. Circulating IgE was not detected. There were no significant changes in erythrocyte values or serum transaminases.