Ethanolic Extract of Emilia sonchifolia Leaves Possess Erythropoietic and Hepatoprotective Effect in Mice Infected with Plasmodium Berghei Berghei

Aim: This study was designed to investigate the effect of ethanolic extracts of the leaves of Emilia sonchifolia on the haematological parameters and histomorphology of the liver of male Swiss albino mice infected with Plasmodium berghei berghei (Pbb).Material and Methods: 35 mice were divided into; Group 1 (control) given normal saline 0.3 ml, Group 2 passaged with Pbb only, Group 3 passaged with Pbb, and then treated with Coartem®, Group 4 treated with E. sonchifolia 325 mg/kg only, Group 5 treated with E. sonchifolia 650 mg/kg only, Group 6 passaged with Pbb then treated with E. sonchifolia 325 mg/kg, while Group 7 was passaged with Pbb then treated with E. sonchifolia 650 mg/kg. Pbb was passaged intraperitoneally, while the test drug and extracts was given via orogavage once daily.Results: The result showed significantly (P<0.001) reduced RBC parameters at in Group 5 treated with 650 mg/kg similar with Group 2 compared to Group 1, while there was significant (P<0.01) increased WBC and differentials in Parasitized groups compared with Group 1. The micrographs showed slightly inflamed nuclei in Group 4, with few nuclei shrinkage Group 5, whereas in the parasitized groups treated with the extract there appeared to be hepatoprotection compared to Group 2.Conclusion: In conclusion, the extract promotes erythropoiesis at 325 mg/kg, but was haemolytic at 650 mg/kg, and exerts its effect possibly through an agonistic and a synergistic activity of its rich bioactive ingredients. It showed mild toxic effect in the histomorphology of the non-parasitized mice at 325 mg/kg and 650 mg/kg, and also appeared to offer hepatoprotection in parasitized mice compared to the parasitized group that had no treatment

Angiotensin receptors and β-catenin regulate brain endothelial integrity in malaria.

Cerebral malaria is characterized by cytoadhesion of Plasmodium falciparum-infected red blood cells (Pf-iRBCs) to endothelial cells in the brain, disruption of the blood-brain barrier, and cerebral microhemorrhages. No available antimalarial drugs specifically target the endothelial disruptions underlying this complication, which is responsible for the majority of malaria-associated deaths. Here, we have demonstrated that ruptured Pf-iRBCs induce activation of β-catenin, leading to disruption of inter-endothelial cell junctions in human brain microvascular endothelial cells (HBMECs). Inhibition of β-catenin-induced TCF/LEF transcription in the nucleus of HBMECs prevented the disruption of endothelial junctions, confirming that β-catenin is a key mediator of P. falciparum adverse effects on endothelial integrity. Blockade of the angiotensin II type 1 receptor (AT1) or stimulation of the type 2 receptor (AT2) abrogated Pf-iRBC-induced activation of β-catenin and prevented the disruption of HBMEC monolayers. In a mouse model of cerebral malaria, modulation of angiotensin II receptors produced similar effects, leading to protection against cerebral malaria, reduced cerebral hemorrhages, and increased survival. In contrast, AT2-deficient mice were more susceptible to cerebral malaria. The interrelation of the β-catenin and the angiotensin II signaling pathways opens immediate host-targeted therapeutic possibilities for cerebral malaria and other diseases in which brain endothelial integrity is compromised

Angiotensin II Moderately Decreases Plasmodium Infection and Experimental Cerebral Malaria in Mice.

Angiotensin II, a peptide hormone that regulates blood pressure, has been proposed as a protective factor against cerebral malaria based on a genetic analysis. In vitro studies have documented an inhibitory effect of angiotensin II on Plasmodium growth, while studies using chemical inhibitors of angiotensin II in mice showed protection against experimental cerebral malaria but not major effects on parasite growth. To determine whether the level of angiotensin II affects Plasmodium growth and/or disease outcome in malaria, elevated levels of angiotensin II were induced in mice by intradermal implantation of osmotic mini-pumps providing constant release of this hormone. Mice were then infected with P. berghei and monitored for parasitemia and incidence of cerebral malaria. Mice infused with angiotensin II showed decreased parasitemia seven days after infection. The development of experimental cerebral malaria was delayed and a moderate increase in survival was observed in mice with elevated angiotensin II, as confirmed by decreased number of cerebral hemorrhages compared to controls. The results presented here show for the first time the effect of elevated levels of angiotensin II in an in vivo model of malaria. The decreased pathogenesis observed in mice complements a previous human genetic study, reinforcing the hypothesis of a beneficial effect of angiotensin II in malaria

Ang II inhibits <i>P</i>. <i>falciparum</i> growth <i>in vitro</i> and <i>P</i>. <i>berghei</i> growth in mice.

<p>A) Parasite levels in cultures of <i>P</i>. <i>falciparum</i> incubated with different concentrations of Ang II <i>in vitro</i>. Ratio of day 0 (initial parasitemia) to day 1 (right axis, circles) and percentage rupture of infected erythrocytes (left axis, squares). B) Parasitemia was determined in groups of mice that were infected with <i>P</i>. <i>berghei</i> (day 0) and had been subjected (n = 8; circles) or not (n = 8; squares) to implantation of subcutaneous mini-pumps releasing saline buffer. C) Parasitemia of groups of mice infected with <i>P</i>. <i>berghei</i>: control (n = 14; circles), implanted with intradermal micro-pumps releasing Ang II at 100 ng/kg/min (n = 15; squares) or 500 ng/kg/min (n = 15; triangles). Number of surviving mice in each group are indicated in the table. Mice numbers decrease due to experimental cerebral malaria induced death (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0138191#pone.0138191.g002" target="_blank">Fig 2B</a>). (B,C) Statistical analysis by t-Student (B) and Kruskal Wallis (C). Average plus standard error is shown. * <i>p</i><0.05; **<i>p</i><0.01; ***<i>p</i><0.001.</p

Ang II decreases brain hemorrhages, delays experimental cerebral malaria and increases survival of mice.

<p>Groups of mice as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0138191#pone.0138191.g001" target="_blank">Fig 1C</a>, control (black circles); Ang II at 100 and 500 ng/kg/min (black squares and triangles, respectively) were observed twice a day for determination of cerebral malaria based on neurological symptoms (as described in methods) (A) and survival (time of euthanasia) (B). Kaplan-Meier analyses were conducted to determine differences among the groups. Cerebral malaria and survival distribution of the groups were significantly different (<i>p</i><0.010 and <i>p</i><0.013, respectively). Pairwise log rank comparison after applying Bonferroni correction (statistical significance accepted at the <i>p</i><0.0167 level) showed that for cerebral malaria there was a statistically significant difference between control <i>vs</i> Ang II (100) (<i>p</i> = 0.0021) but not <i>vs</i> Ang II (500) (<i>p</i> = 0.0258). For survival, both Ang II groups showed significant differences vs control group (<i>p</i> = 0.0087 and <i>p</i> = 0.0100 for Ang II (100) and Ang II (500) <i>vs</i> control, respectively). No significant differences were found between angiotensin groups, Ang II (100) and Ang II (500) (<i>p</i> = 0.511 and <i>p</i> = 0.524 for cerebral malaria and survival respectively). Histological sections of the brains of mice control (C), Ang II at 100 ng/kg/min (D) and Ang II at 500 ng/kg/min (E) were analyzed for the presence and size of hemorrhages. Bar is 50μm. Quantification of the number (F) and size (G) of hemorrhages per mm². Mice that were sacrificed with a cerebral malaria score of 3 (black circles), 4 (blue circles) or 5 (red circles) and mice that did not develop cerebral malaria (gray circles) are indicated. Average values for each mouse are shown. **<i>p</i><0.01 by ANOVA. No significant differences were observed between groups in (G).</p