AhR-mediated lipid peroxidation contributes to TCDD-induced cardiac defects in zebrafish.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), a persistent environmental contaminant that activates the aryl hydrocarbon receptor (AhR) pathway, has been reported to cause cardiac damage. However, the mechanism underlying AhR-induced cardiac defects in response to TCDD exposure remains unclear. In this study, we characterized the impacts of TCDD exposure on heart morphology and cardiac function in zebrafish. TCDD exposure in the early developmental stage of zebrafish embryos led to morphological heart malformation and pericardial edema, concomitant with reduced cardiac function. These cardiac defects were attenuated by inhibiting AhR activity with CH223191. Transcriptome profiling showed that, along with an upregulation of the AhR signaling pathway by TCDD treatment, the expression of pro-ferroptotic genes was upregulated, while that of genes implicated in glutathione metabolism were downregulated. Moreover, lipid peroxidation, as indicated by malonaldehyde (MDA) production, was increased in TCDD-exposed cardiac tissue. Accordingly, inhibiting lipid peroxidation with liproxstatin-1 reversed the adverse cardiac effects induced by TCDD treatment. Taken together, our findings demonstrate that AhR-mediated lipid peroxidation contributes to cardiac defects in the early developmental stage in zebrafish embryos exposed to TCDD.

Comprehensive analysis of mRNA-lncRNA co-expression profiles in mouse brain during infection with Toxoplasma gondii.

Toxoplasma gondii is an obligate intracellular protozoan parasite which seriously threatens the health of domestic animals and humans. Long non-coding RNAs (lncRNAs) are non-protein-coding transcripts greater than 200 nucleotides, which are widely involved in transcriptional and epigenetic regulations. However, little is known about the roles of host lncRNAs in the response to T. gondii infections. In this study, using Illumina sequencing technology, we analyzed the expression profiles of mRNAs and lncRNAs in BALB/c mouse brain following infection by T. gondii PRU strain (type II genotype) cysts. The identified differentially expressed (DE) RNAs were subjected to bioinformatics analysis. A total of 2,090 annotated lncRNAs along with 3,577 novel lncRNAs were identified. In the acutely infected mouse brain, a total of 330 mRNAs and 19 lncRNAs were dys-regulated, whereas 136 DE mRNAs and 9 DE lncRNAs were identified in chronically infected mouse brain. GO analysis revealed that these DE mRNAs identified at acute infection stage were involved in immune response, whereas DE mRNAs found at chronic infection stage were mostly enriched in response to protozoan. KEGG analysis showed that DE mRNAs were significantly enriched in disease related pathways. In addition, the putative mRNA-lncRNA co-expression network was constructed, and several hub regulatory RNAs were identified based on the transcriptome data. This study firstly characterized the co-expression profile of mRNAs and lncRNAs in mouse brain infected with T. gondii and provided a framework for further studies of the roles of lncRNAs in host neuropathology during toxoplasmosis progression.

Downregulation of lncRNA-11496 in the Brain Contributes to Microglia Apoptosis via Regulation of Mef2c in Chronic T. gondii Infection Mice.

Though it is well known that chronic infections of Toxoplasma gondii (T. gondii) can induce mental and behavioral disorders in the host, little is known about the role of long non-coding RNAs (lncRNAs) in this pathological process. In this study, we employed an advanced lncRNAs and mRNAs integration chip (Affymetrix HTA 2.0) to detect the expression of both lncRNAs and mRNAs in T. gondii Chinese 1 strain infected mouse brain. As a result, for the first time, the downregulation of lncRNA-11496 (NONMMUGO11496) was identified as the responsible factor for this pathological process. We showed that dysregulation of lncRNA-11496 affected proliferation, differentiation and apoptosis of mouse microglia. Furthermore, we proved that Mef2c (Myocyte-specific enhancer factor 2C), a member of the MEF2 subfamily, is the target gene of lncRNA-11496. In a more detailed study, we confirmed that lncRNA-11496 positively regulated the expression of Mef2c by binding to histone deacetylase 2 (HDAC2). Importantly, Mef2c itself could coordinate neuronal differentiation, survival, as well as synapse formation. Thus, our current study provides the first evidence in terms of the modulatory action of lncRNAs in chronic toxoplasmosis in T. gondii infected mouse brain, providing a solid scientific basis for using lncRNA-11496 as a therapeutic target to treat T. gondii induced neurological disorder.

miRNA and circRNA expression patterns in mouse brain during toxoplasmosis development.

BACKGROUND: Increasing evidence has shown that circular RNAs (circRNAs) are involved in neurodegenerative disorders, but their roles in neurological toxoplasmosis are yet to know. This study examined miRNA and circRNA expressions in mouse brain following oral infection with T. gondii Pru strain. RESULTS: Total RNA extracted from acutely infected (11 days post infection (DPI)), chronically infected (35 DPI) and uninfected mouse brain samples were subjected to genome-wide small RNA sequencing. In the acutely infected mice, 9 circRNAs and 20 miRNAs were upregulated, whereas 67 circRNAs and 28 miRNAs were downregulated. In the chronically infected mice, 2 circRNAs and 42 miRNAs were upregulated, whereas 1 circRNA and 29 miRNAs were downregulated. Gene ontology analysis predicted that the host genes that produced the dysregulated circRNAs in the acutely infected brain were primarily involved in response to stimulus and ion binding activities. Furthermore, predictive interaction networks of circRNA-miRNA and miRNA-mRNA were constructed based on genome-wide transcriptome sequencing and computational analyses, which might suggest the putative functions of miRNAs and circRNAs as a large class of post-transcriptional regulators. CONCLUSIONS: These findings will shed light on circRNA-miRNA interactions during the pathogenesis of toxoplasmosis, and they will lay solid foundation for studying the potential regulation roles of miRNAs and circRNAs in T. gondii induced pathogenesis.

Molecular Detection of Toxoplasma gondii in the Slaughter Sheep and Goats from Shandong Province, Eastern China.

It is generally recognized that sheep are susceptible to Toxoplasma gondii and play a very important role in the transmission of toxoplasmosis to humans. In China, sheep toxoplasmosis has been reported in some regions based on serological investigations. However, little is known about sheep toxoplasmosis in Shandong province, eastern China. Thus, this study was conducted to investigate the prevalence of T. gondii infection in the slaughter sheep and goats from three cities (Weihai, Yantai, and Rizhao) of Shandong province, eastern China. From November 2016 to March 2018, a total of 692 meat samples (438 sheep and 254 goats) were collected and detected by a seminested PCR-targeted T. gondii B1 gene. The overall prevalence of T. gondii in sheep and goats were 9.84% and 10.73%, respectively. Meat collected from rural markets (16.04%) had a significantly higher T. gondii prevalence than those collected from supermarkets (6.84%) (p < 0.001). Moreover, sheep and goats raised in backyard were more easily to be infected by T. gondii compared with those raised in farms (p < 0.001). This is the first report of the molecular prevalence of T. gondii infection in sheep and goats in Shandong province, eastern China, which would provide effective data for prevention and control of sheep and human toxoplasmosis in China.

Immunogenicity of a Virus-Like-Particle Vaccine Containing Multiple Antigenic Epitopes of Toxoplasma gondii Against Acute and Chronic Toxoplasmosis in Mice.

There is no effective protective vaccine against human toxoplasmosis, which is a potential threat to nearly a third of the world population. Vaccines based on virus-like particles (VLPs) have been highly successful in humans for many years, but have rarely been applied against Toxoplasma gondii infection. In this study, we inserted a B cell epitope (SAG182-102 or SAG1301-320), a CD8+ cell epitope (HF10 or ROP7), and a CD4+ cell epitope (AS15) of T. gondii into a truncated HBcΔ(amino acids1-149) particle to construct four chimeric VLP vaccine formulations, i.e., HBcΔH82, HBcΔH301, HBcΔ R82, and HBcΔ R301. When these chimeric HBc particles were expressed in Escherichia coli, they showed icosahedral morphology similar to that of the original VLPs and were evaluated as vaccine formulations against acute and chronic toxoplasmosis in a mouse model (BALB/c mice (H-2d). All these chimeric HBc VLPs induced strong humoral and cellular immune responses with high IgG antibody titers and interferon(IFN)-γ production. Only the mice immunized with HBcΔH82 showed prolonged survival time (15.6 ± 3.8 vs. 5.6 ± 0.8 days) against acute infection with RH tachyzoites and decrease in brain parasite load (1,454 ± 239 vs. 2,091 ± 263) against chronic infection with Prugniuad cysts, as compared to the findings for the control group. These findings suggest that HBc VLPs would act as an effective carrier for delivering effective multiple antigenic epitopes and would be beneficial for developing a safe and long-acting vaccine against toxoplasmosis.