The Role of Lipopeptidophosphoglycan in the Immune Response to Entamoeba histolytica

The sensing of Pathogen Associated Molecular Patterns (PAMPs) by innate immune receptors, such as Toll-like receptors (TLRs), is the first step in the inflammatory response to pathogens. Entamoeba histolytica, the etiological agent of amebiasis, has a surface molecule with the characteristics of a PAMP. This molecule, which was termed lipopeptidophosphoglycan (LPPG), is recognized through TLR2 and TLR4 and leads to the release of cytokines from human monocytes, macrophages, and dendritic cells; LPPG-activated dendritic cells have increased expression of costimulatory molecules. LPPG activates NKT cells in a CD1d-dependent manner, and this interaction limits amebic liver abscess development. LPPG also induces antibody production, and anti-LPPG antibodies prevent disease development in animal models of amebiasis. Because LPPG is recognized by both the innate and the adaptive immune system (it is a “Pamptigen”), it may be a good candidate to develop a vaccine against E. histolytica infection and an effective adjuvant

Ecological and Physiological Studies of Gymnodinium catenatum in the Mexican Pacific: A Review

This review presents a detailed analysis of the state of knowledge of studies done in Mexico related to the dinoflagellate Gymnodinium catenatum, a paralytic toxin producer. This species was first reported in the Gulf of California in 1939; since then most studies in Mexico have focused on local blooms and seasonal variations. G. catenatum is most abundant during March and April, usually associated with water temperatures between 18 and 25 ºC and an increase in nutrients. In vitro studies of G. catenatum strains from different bays along the Pacific coast of Mexico show that this species can grow in wide ranges of salinities, temperatures, and N:P ratios. Latitudinal differences are observed in the toxicity and toxin profile, but the presence of dcSTX, dcGTX2-3, C1, and C2 are usual components. A common characteristic of the toxin profile found in shellfish, when G. catenatum is present in the coastal environment, is the detection of dcGTX2-3, dcSTX, C1, and C2. Few bioassay studies have reported effects in mollusks and lethal effects in mice, and shrimp; however no adverse effects have been observed in the copepod Acartia clausi. Interestingly, genetic sequencing of D1-D2 LSU rDNA revealed that it differs only in one base pair, compared with strains from other regions

Pregnant women infected with pandemic H1N1pdm2009 influenza virus displayed overproduction of peripheral blood CD69+ lymphocytes and increased levels of serum cytokines.

The first pandemic of the 21st century occurred in 2009 and was caused by the H1N1pdm influenza A virus. Severe cases of H1N1pdm infection in adults are characterized by sustained immune activation, whereas pregnant women are prone to more severe forms of influenza, with increased morbi-mortality. During the H1N1pdm09 pandemic, few studies assessed the immune status of infected pregnant women. The objective of this study was to evaluate the behavior of several immune markers in 13 H1N1pdm2009 virus-infected pregnant (PH1N1) women, in comparison to pregnant women with an influenza-like illness (ILI), healthy pregnant women (HP) and healthy non-pregnant women (HW). The blood leukocyte phenotypes and the serological cytokine and chemokine concentrations of the blood leukocytes, as measured by flow cytometry, showed that the CD69+ cell counts in the T and B-lymphocytes were significantly higher in the PH1N1 group. We found that pro-inflammatory (TNF-α, IL-1β, IL-6) and anti-inflammatory (IL-10) cytokines and some chemokines (CXCL8, CXCL10), which are typically at lower levels during pregnancy, were substantially increased in the women in the ILI group. Our findings suggest that CD69 overexpression in blood lymphocytes and elevated levels of serum cytokines might be potential markers for the discrimination of H1N1 disease from other influenza-like illnesses in pregnant women

Demographic and obstetric characteristics of the study population.

<p>HW. Healthy women.</p><p>HP. Healthy pregnant women.</p><p>ILI. Pregnant women with influenza-like illness.</p><p>PH1N1. H1N1pdm2009 virus-infected pregnant women.</p><p>Gw. Gestational weeks.</p><p>n/a not applicable.</p><p>*Fisher’s exact test.</p><p>Demographic and obstetric characteristics of the study population.</p

Higher percentage of CD69+ lymphocytes in H1N1pdm2009 virus-infected pregnant women.

<p>The peripheral blood leukocytes from the HW, HP, ILI and PH1N1 women were immunostained with CD3-, CD19-, CD14- and CD69-specific antibodies and analyzed by flow cytometry. Representative data of each group are shown in the dot plots for CD69+CD3+ cells (a). The distribution of CD69 expression on CD3− (b), CD19− (c) or CD14− (d) gated cells. The Kruskal-Wallis test with Dunn’s multiple comparison post-test was performed using the GraphPad Software. The significance values were *p<0.05, **p<0.01, ***p<0.001.</p

Clinical manifestations in the ILI and PH1N1 women.

<p>ILI: Pregnant women with influenza-like illness.</p><p>PH1N1: Confirmed H1N1pdm2009 virus-infected pregnant women.</p><p>*Fisher’s exact test.</p><p>Clinical manifestations in the ILI and PH1N1 women.</p

Serum cytokine concentrations in HW, HP, ILI and PH1N1 women.

<p>Pro-inflammatory TNF-α (a), IL-1β (b) and IL-6 (c) and anti-inflammatory IL-10 (d) cytokines were quantified using a CBA system with flow cytometry. The Kruskal-Wallis test with Dunn’s multiple comparison post-test was performed using the GraphPad Software. The significance values were *p<0.05, **p<0.01, ***p<0.001.</p

Distribution of leukocytes in the blood.

<p>HW. Healthy women.</p><p>HP. Healthy pregnant women.</p><p>ILI. Pregnant women with influenza-like illness.</p><p>PH1N1. H1N1pdm2009 virus-infected pregnant women.</p><p>a. HW vs ILI.</p><p>b. ILI vs PH1N1.</p><p>c. HW vs PH1N1.</p><p>d. HP vs PH1N1.</p><p>e. HW vs HP.</p><p>f. HP vs ILI.</p>±<p>Kruskal-Wallis test with Dunn’s multiple comparison post-test.</p><p>P values: * = p<0.05; ** = p<0.01; *** = p<0.001.</p><p>Distribution of leukocytes in the blood.</p

A Toll/IL-1R/resistance domain-containing thioredoxin regulates phagocytosis in <it>Entamoeba histolytica</it>

<p>Abstract</p> <p>Background</p> <p><it>Entamoeba histolytica</it> is a protozoan parasite that infects humans and causes amebiasis affecting developing countries. Phagocytosis of epithelial cells, erythrocytes, leucocytes, and commensal microbiota bacteria is a major pathogenic mechanism used by this parasite. A Toll/IL-1R/Resistance (TIR) domain-containing protein is required in phagocytosis in the social ameba <it>Dictyostelium discoideum</it>, an ameba closely related to <it>Entamoeba histolytica</it> in phylogeny. In insects and vertebrates, TIR domain-containing proteins regulate phagocytic and cell activation. Therefore, we investigated whether <it>E. histolytica</it> expresses TIR domain-containing molecules that may be involved in the phagocytosis of erythrocytes and bacteria.</p> <p>Methods</p> <p>Using <it>in silico</it> analysis we explored in <it>Entamoeba histolytica</it> databases for TIR domain containing sequences. After silencing TIR domain containing sequences in trophozoites by siRNA we evaluated phagocytosis of erythrocytes and bacteria.</p> <p>Results</p> <p>We identified an <it>E. histolytica</it> thioredoxin containing a TIR-like domain. The secondary and tertiary structure of this sequence exhibited structural similarity to TIR domain family. Thioredoxin transcripts silenced in <it>E. histolytica</it> trophozoites decreased erythrocytes and <it>E. coli</it> phagocytosis.</p> <p>Conclusion</p> <p>TIR domain-containing thioredoxin of <it>E. histolytica</it> could be an important element in erythrocytes and bacteria phagocytosis.</p