A comparison of rat models that best mimic immune-driven preeclampsia in humans.

Preeclampsia (PE), a hypertensive pregnancy disorder, can originate from varied etiology. Placenta malperfusion has long been considered the primary cause of PE. However, we and others have showed that this disorder can also result from heightened inflammation at the maternal-fetal interface. To advance our understanding of this understudied PE subtype, it is important to establish validated rodent models to study the pathophysiology and test therapies. We evaluated three previously described approaches to induce inflammation-mediated PE-like features in pregnant rats: 1) Tumor necrosis factor-α (TNF-α) infusion via osmotic pump from gestational day (GD) 14-19 at 50ng/day/animal; 2) Polyinosinic:polycytidylic acid (Poly I:C) intraperitoneal (IP) injections from GD 10-18 (alternate days) at 10mg/kg/day/animal; and, 3) Lipopolysaccharide (LPS) IP injections from GD 13-18 at 20ug-70ug/kg/day per animal. Maternal blood pressure was measured by tail-cuff. Upon sacrifice, fetal and placenta weights were recorded. Placenta histomorphology was assessed using H&E sections. Placenta inflammation was determined by quantifying TNF-α levels and inflammatory gene expression. Placenta metabolic and mitochondrial health were determined by measuring mitochondrial respiration rates and placenta NAD+/NADH content. Of the three rodent models tested, we found that Poly I:C and LPS decreased both fetal weight and survival; and correlated with a reduction in region specific placenta growth. As the least effective model characterized, TNF-α treatment resulted in a subtle decrease in fetal/placenta weight and placenta mitochondrial respiration. Only the LPS model was able to induce maternal hypertension and exhibited pronounced placenta metabolic and mitochondrial dysfunction, common features of PE. Thus, the rat LPS model was most effective for recapitulating features observed in cases of human inflammatory PE. Future mechanistic and/or therapeutic intervention studies focuses on this distinct PE patient population may benefit from the employment of this rodent model of PE.

Both C57BL/KsJ (H2d haplotype) and CB10-H2 (H2b haplotype) mice are highly susceptible to congenital toxoplasmosis.

Congenital toxoplasmosis may cause abortion, neonatal death, or foetal abnormalities. Despite little information from human studies, a genetic influence over congenital disease was demonstrated and, host genome have been implicated to resistance/susceptibility to Toxoplasma gondii infection in both human and mice. It was previously shown that BALB/c mice (H2d) were more resistant to congenital toxoplasmosis than C57BL/6 mice (H2b). However, it is unclear whether these differences are attributable to the MHC haplotype or to other components of the mouse's genetic background. Therefore, in this work, we intend to address this question by investigating the pregnancy outcome in H2d -congenic C57BL/6 mice (C57BL/KsJ-H2d) and H2b-congenic BALB/c mice (CB10-H2-H2b). For this, animals were infected by intragastric route on the first day of pregnancy and examined on days 8 (8dP/8dI) or 18 (18dP/18dI) of gestation and infection. The pregnancy outcome, parasite burden, systemic cytokine profile and antibody response to infection were evaluated. Infected mice showed adverse pregnancy outcomes, in parallel low parasite detection in the uterus/placenta, being that the C57BL/KsJ showed the worst results in relation to CB10-H2 mice. Both mouse lineages showed an increase in IFN-γ and TNF levels systemically on 8dP/8dI and on 18dP/18dI, and C57BL/KsJ showed an increase in IL-6 levels in both gestation/infection periods. Additionally, C57BL/KsJ showed 7- and 7-fold increase in IL-6, 4- and 2.5-fold increase in IFN-γ and, 6- and 4-fold increase in TNF production on 8dP/8dI and 18dP/18dI, respectively in association with 1.5-fold decrease in TGF-ß levels on 8dP/8dI compared to CB10-H2 mice. In conclusion, the high IFN-γ and TNF serum levels observed in C57BL/KsJ (H2d) and CB10-H2 (H2b) mice were involved in the poor pregnancy outcomes in congenital toxoplasmosis. In addition, the higher IFN-γ, IL-6 and TNF levels detected in C57BL/KsJ in relation to CB10-H2 mice on 8dP/8dI seem to be related to the genetic background of C57BL/6J mice that may have contributed to the worse pregnancy outcome in this mouse lineage.

Toxoplasma gondii Infection Decreases Intestinal 5-Lipoxygenase Expression, while Exogenous LTB4 Controls Parasite Growth.

5-Lipoxygenase (5-LO) is an enzyme required for the production of leukotrienes and lipoxins and interferes with parasitic infections. In vitro, Toxoplasma gondii inhibits leukotriene B4 (LTB4) production, and mice deficient in 5-LO are highly susceptible to infection. The aim of this study was to investigate the effects of the pharmacological inhibition of the 5-LO pathway and exogenous LTB4 supplementation during experimental toxoplasmosis. For this purpose, susceptible C57BL/6 mice were orally infected with T. gondii and treated with LTB4 or MK886 (a selective leukotriene inhibitor through inhibition of 5-LO-activating protein [FLAP]). The parasitism, histology, and immunological parameters were analyzed. The infection decreased 5-LO expression in the small intestine, and treatment with MK886 reinforced this reduction during infection; in addition, MK886-treated infected mice presented higher intestinal parasitism, which was associated with lower local interleukin-6 (IL-6), interferon gamma (IFN-γ), and tumor necrosis factor (TNF) production. In contrast, treatment with LTB4 controlled parasite replication in the small intestine, liver, and lung and decreased pulmonary pathology. Interestingly, treatment with LTB4 also preserved the number of Paneth cells and increased α-defensins expression and IgA levels in the small intestine of infected mice. Altogether, these data demonstrated that T. gondii infection is associated with a decrease in 5-LO expression, and on the other hand, treatment with the 5-LO pathway product LTB4 resulted in better control of parasite growth in the organs, adding to the knowledge about the pathogenesis of T. gondii infection.

The imbalance of TNF and IL-6 levels and FOXP3 expression at the maternal-fetal interface is involved in adverse pregnancy outcomes in a susceptible murine model of congenital toxoplasmosis.

Vertical transmission of Toxoplasma gondii leads to adverse pregnancy outcomes depending on the time at which the infection occurs and the immunological state of the mother. C57BL/6 and BALB/c mice have been described as susceptible and resistant mouse lineages to congenital T. gondii infection, respectively. This study aimed to elucidate the systemic and local cytokine profile of pregnant mice infected with T. gondii and whether the expression of the transcription factor FOXP3, related to T regulatory cells, is associated with the resistance/susceptibility of these lineages of mice in the context of experimental congenital toxoplasmosis. For this purpose, C57BL/6 and BALB/c females were orally infected with the T. gondii ME-49 strain on the day of vaginal plug detection or day 14 of gestation, examined 7 or 5 days later, respectively, as models of early and late pregnancy. Cytokine levels were measured systemically and in the uterus/placenta. Additionally, the uterus/placenta were evaluated macroscopically for resorption rates and histologically for parasite and FOXP3 immunostaining. The FOXP3 protein expression was also evaluated by western blotting assay. It was found that, during early pregnancy, the infection leads to high IFN-γ, TNF and IL-6 levels systemically, with the TNF levels being higher in C57BL/6 mice. At the maternal-fetal interface, the infection induced high levels of IFN-γ in both mouse lineages; however, higher levels were observed in BALB/c, while high TNF and IL-6 levels were found in C57BL/6, but not in BALB/c mice. In contrast, in late gestation, T. gondii interfered less strongly with the cytokine profile. In early pregnancy, a reduction of FOXP3 expression at the maternal-fetal interface of infected mice was also observed, and the reduction was larger in C57BL/6 compared with BALB/c mice. Additionally, the parasite was seldom found in the uterus/placenta. Thus, the worse pregnancy outcomes observed in C57BL/6 mice were associated with higher TNF systemically, and TNF and IL-6 at the maternal-fetal interface, with lower FOXP3 expression.

Anti-parasitic activity of Annona muricata L. leaf ethanolic extract and its fractions against Toxoplasma gondii in vitro and in vivo.

ETHNOPHARMACOLOGICAL RELEVANCE: Sulfadiazine and pyrimethamine are the two drugs used as part of the standard therapy for toxoplasmosis, however; they may cause adverse side effects and fail to prevent relapse in many patients, rendering infected individuals at risk of reactivation upon becoming immunocompromised. Extracts from various parts of Annona muricata have been widely used medicinally for the management, control and/or treatment of several human diseases, acting against parasites that cause diseases in humans. AIM OF THE STUDY: This study was performed to investigate the action of the ethanolic extract of A. muricata (EtOHAm) and its fractions in the control of the apicomplexan parasite Toxoplasma gondii in vitro and in vivo, and the effect of EtOHAm on the inflammatory response and lipid profile alteration induced by in vivo T. gondii infection. MATERIALS AND METHODS: The cytotoxicity of EtOHAm and its fractions ethyl acetate (EtOAcAm), n-butanol (BuOHAm), aqueous (H2OAm), hexane (HexAm) and dichloromethane (CH2Cl2Am) was evaluated in NIH/3T3 fibroblasts using the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The cells were infected with T. gondii, treated with the extracts, and parasite proliferation was analyzed. For the in vivo experiments, C57BL/6 mice were orally infected with T. gondii and, treated with different concentrations of extract fractions that were effective in vitro (EtOHAm, EtOAcAm, HexAm and CH2Cl2Am). Tissue parasitism, histological alterations, systemic cytokine and lipid profile were investigated. RESULTS: EtOHAm, EtOAcAm, BuOHAm, H2OAm presented low cytotoxicity until doses of 200 µg/mL, while HexAm and CH2Cl2Am presented toxicity from doses of 100µg/mL. EtOHAm, HexAm and CH2Cl2Am decreased the parasitism in vitro, presenting a therapeutic index of 2.62, 2.44, and 2.96, respectively. In vivo, EtOHAm, HexAm and CH2Cl2Am improved the survival rate of infected animals, however, only EtOHAm was able to decrease the parasitism in the small intestine and lung. Additionally, EtOHAm decreased the systemic interferon (IFN)-γ and tumor necrosis factor (TNF) systemically in infected mice, and was able to maintain the triglycerides and very-low-density lipoprotein (VLDL) lipid fractions at similar levels to uninfected animals. Although treatment with EtOHAm could not control the inflammation induced by oral infection in the tissues analyzed, it was able to preserve the number of goblet cells in the small intestine. CONCLUSIONS: Ethanolic A. muricata leaf extract could be considered as a good candidate for the development of a complementary/alternative therapy against toxoplasmosis, and also as an anti-inflammatory alternative for decreasing TNF and IFN-γ concentrations and lipid fractions in specific diseases.