Transcriptome analysis of mouse brain infected with Toxoplasma gondii

Brain -cyst-driven genes expression in Toxoplasma Gondii Tehran strain: a parasitic-immunogenicity assessment by dint of RNA-Seq

Toxoplasma gondii (T. gondii) is an obligate intracellular parasite of warm-blooded vertebrates. At present, High-throughput RNA sequencing analysis have made it possible to determine the role of effective genes in host immune response. The aim of the present study is to global transcriptome analysis of the brain of mice infected with T. gondii Tehran strain for the first time and also to evaluate the expression of effective genes in the chronic form of infection. RNA was extracted from the samples and the library was prepared and sequenced using the IlluminaNovaSeq 6000 system. After analyzing gene expression changes, the results were confirmed by real-time method. We found 125 genes that were significantly differentially expressed between infected and non-infected samples (p < 0.0005). Gene ontology analysis revealed that the expression of many genes is critical for pathways such as T cell receptor signaling pathway, Natural Killer cell mediated cytotoxicity, Lysosome and Apoptosis of the host. As infection with Tehran strain leads to chronic infection in mice, therefore, we investigated the genes effective in creating the chronic form of Toxoplasma infection. The comparative analysis of genes showed increases in the expression of genes ctla4, ccl4, cd3e, c3, lcn2, gbp5, usp18, cyba, tap1 and samhd1 in the in the infected sample, which highlights their role in causing chronic infection. RNA-seq provides a valuable tool for analyzing host transcriptomes, better understanding the parasite-host interaction, and developing future drug and vaccine targets.

Protective efficacy of recombinant Toxoplasma gondii dense granule protein 15 against toxoplasmosis in C57BL/6 mice

Toxoplasma gondii is a pervasive protozoan parasite that is responsible for significant zoonoses. A wide array of vaccines using different effector molecules of T. gondii have been studied worldwide to control toxoplasmosis. None of the existing vaccines are sufficiently effective to confer protective immunity. Among the different Toxoplasma-derived effector molecules, T. gondii dense granule protein 15 from the type II strain (GRA15 (II)) was recently characterized as an immunomodulatory molecule that induced host immunity via NF-κB. Therefore, we assessed the immunostimulatory and protective efficacy of recombinant GRA15 (II) (rGRA15) against T. gondii infection in a C57BL/6 mouse model. We observed that rGRA15 treatment increased the production of IL-12p40 from mouse peritoneal macrophages in vitro. Immunization of mice with rGRA15 induced the production of anti-TgGRA15-specific IgG, IgG1 and IgG2c antibodies. The rGRA15-sensitized spleen cells from mice inoculated with the same antigen strongly promoted spleen cell proliferation and IFN-γ production. Immunization with rGRA15 significantly enhanced the survival rate of mice and dramatically decreased parasite burden in mice challenged with the Pru (type II) strain. These results suggested that rGRA15 triggered humoral and cellular immune responses to control infection. However, all of the immunized mice died when challenged with the GRA15-deficient Pru strain or the RH (type I) strain. These results suggest that GRA15 (II)-dependent immunity plays a crucial role in protection against challenge infection with the type II strain of T. gondii. This study is the first report to show GRA15 (II) as a recombinant vaccine antigen against Toxoplasma infection.

Expression profiles of host miRNAs and circRNAs and ceRNA network during Toxoplasma gondii lytic cycle

Toxoplasma gondii is an opportunistic protozoan parasite that is highly prevalent in the human population and can lead to adverse health consequences in immunocompromised patients and pregnant women. Noncoding RNAs, such as microRNAs (miRNAs) and circular RNAs (circRNAs), play important regulatory roles in the pathogenesis of many infections. However, the differentially expressed (DE) miRNAs and circRNAs implicated in the host cell response during the lytic cycle of T. gondii are unknown. In this study, we profiled the expression of miRNAs and circRNAs in human foreskin fibroblasts (HFFs) at different time points after T. gondii infection using RNA sequencing (RNA-seq). We identified a total of 7, 7, 27, 45, 70, 148, 203, and 217 DEmiRNAs and 276, 355, 782, 1863, 1738, 6336, 1229, and 1680 DEcircRNAs at 1.5, 3, 6, 9, 12, 24, 36, and 48 h post infection (hpi), respectively. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses revealed that the DE transcripts were enriched in immune response, apoptosis, signal transduction, and metabolism-related pathways. These findings provide new insight into the involvement of miRNAs and circRNAs in the host response to T. gondii infection.

Retinal ferroptosis as a critical mechanism for the induction of retinochoroiditis during ocular toxoplasmosis

Toxoplasmosis is a major infectious disease, affecting approximately one-third of the world's population; its main clinical manifestation, ocular toxoplasmosis (OT), is a severe sight-threatening disease. Nevertheless, the diagnosis of OT is based on clinical findings, which needs improvement, even with biochemical tests, such as polymerase chain reaction and antibody detections. Furthermore, the efficacy of OT-targeted treatment is limited; thus, additional measures for diagnosis and treatments are needed. Here, we for the first time report a significantly reduced iron concentration in the vitreous humor (VH) of human patients infected with OT. To obtain further insights into molecular mechanisms, we established a mouse model of T. gondii infection, in which intravitreally injected tracer 57Fe, was accumulated in the neurosensory retina. T. gondii-infected eyes showed increased lipid peroxidation, reduction of glutathione peroxidase-4 expression and mitochondrial deformity in the photoreceptor as cristae loss. These findings strongly suggest the involvement of ferroptotic process in the photoreceptor of OT. In addition, deferiprone, an FDA-approved iron chelator, reduced the iron uptake but also ameliorated toxoplasma-induced retinochoroiditis by reducing retinal inflammation. In conclusion, the iron levels in the VH could serve as diagnostic markers and iron chelators as potential treatments for OT.

Chronic Toxoplasma infection affects gene expression of drug-metabolizing enzymes in mouse liver

Toxoplasma gondii is an intracellular protozoan parasite causing toxoplasmosis, an infectious disease affecting warm-blooded vertebrates worldwide. Many drug-metabolizing enzymes are located in the liver, a major organ of drug metabolism, and their function can be affected by pathogen infection.Using next-generation sequencing (RNA-seq) and quantitative polymerase chain reaction (qPCR), changes in the hepatic expressions of drug-metabolizing enzymes were analysed in mice chronically infected with T. gondii. The analysis found that, among drug-metabolizing enzymes, 22 genes were upregulated and 28 genes were downregulated (≥1.5-fold); of these 5 and 17 genes, respectively, were cytochromes P450 (Cyp or P450).Subsequent qPCR analysis showed that six P450 genes were upregulated significantly (≥1.5-fold, p < 0.05), namely, Cyp1b1, Cyp2c29, Cyp2c65, Cyp2d9, Cyp2d12, and Cyp3a59, whereas nine P450 genes were downregulated significantly (≥1.5-fold, p < 0.05), namely, Cyp2c38, Cyp2c39, Cyp2c44, Cyp2c69, Cyp2d40, Cyp2e1, Cyp3a11, Cyp3a41, and Cyp3a44.Moreover, metabolic assays in infected mouse liver using typical P450 substrates revealed that midazolam 1'-hydroxylation and testosterone 2-hydroxylation activities decreased significantly (≥1.5-fold, p < 0.05), whereas testosterone 16-hydroxylation activity increased significantly (≥1.5-fold, p < 0.05).Chronic Toxoplasma infection affects drug metabolism, at least partly, by altering the gene expressions of drug-metabolizing enzymes, including P450s.

A transcriptional network required for bradyzoite development in Toxoplasma gondii is dispensable for recrudescent disease

Identification of regulators of Toxoplasma gondii bradyzoite development and cyst formation is the most direct way to address the importance of parasite development in long-term persistence and reactivation of this parasite. Here we show that a T. gondii gene (named Regulator of Cystogenesis 1; ROCY1) is sufficient for T. gondii bradyzoite formation in vitro and in vivo. ROCY1 encodes an RNA binding protein that has a preference for 3' regulatory regions of hundreds of T. gondii transcripts, and its RNA-binding domains are required to mediate bradyzoite development. Female mice infected with ΔROCY1 parasites have reduced (>90%) cyst burden. While viable parasites can be cultivated from brain tissue for up to 6 months post-infection, chronic brain-resident ΔROCY1 parasites have reduced oral infectivity compared to wild type. Despite clear defects in bradyzoite formation and oral infectivity, ΔROCY1 parasites were able to reactivate with similar timing and magnitude as wild type parasites for up to 5 months post-infection. Therefore while ROCY1 is a critical regulator of the bradyzoite developmental pathway, it is not required for parasite reactivation, raising new questions about the persisting life stage responsible for causing recrudescent disease.

Understanding of molecular basis of histological graded horn cancer by transcriptome profiling

Horn cancer is most devastating and prominent cancer in Indian zebu cattle that affects socio-economic condition of small-scale farmers who depends on their cattle for farm work. Development in the field for genomics through next generation sequencing and bioinformatics advancement have helped to identify genes which have a role in horn cancer development. Histopathological examination of cancerous tissues of horn revealed myxomatous changes, well, moderate and poorly differentiated squamous cell carcinoma. Differential gene expression analysis showed 40, 11, 66 and 29 upregulated genes and 10, 14, 08 and 07 down-regulated genes in myxomatous, well, moderate and poorly differentiated squamous cell carcinoma as compared to normal. Significant differentially expressed genes are related to cell development, cell proliferation, cell-cell communication, cell signaling and angiogenesis which are linked to Akt pathway, mTOR pathway and Wnt pathway. Activity of these genes and related pathways have already been established about their role in development of cancer. Among the candidate genes; keratin family, keratin family related gene, chemokine signaling and cytokines signaling associated genes could be a prominent target for the development of stage specific prognosis marker after further detailed study at large sample population level. CSTA, PTN, SPP1 genes have upregulation in all stages of cancer and they have enrolled as biomarkers for horn cancer.

Coixol ameliorates Toxoplasma gondii infection-induced lung injury by interfering with T. gondii HSP70/TLR4/NF-κB signaling pathway

Toxoplasma gondii (T. gondii) is an obligate intracellular protozoan parasite that causes pulmonary toxoplasmosis, although its pathogenesis is incompletely understood. There is no cure for toxoplasmosis. Coixol, a plant polyphenol extracted from coix seeds, has a variety of biological activities. However, the effects of coixol on T. gondii infection have not been clarified. In this study, we infected a mouse macrophage cell line (RAW 264.7) and BALB/c mice with the T. gondii RH strain to establish infection models in vitro and in vivo, respectively, to explore protective effects and potential mechanisms of coixol on lung injury caused by T. gondii infection. Anti-T. gondii effects and underlying anti-inflammatory mechanisms of coixol were investigated by real-time quantitative PCR, molecular docking, localized surface plasmon resonance, co-immunoprecipitation, enzyme-linked immunosorbent assay, western blotting, and immunofluorescence microscopy. The results show that coixol inhibits T. gondii loads and T. gondii-derived heat shock protein 70 (T.g.HSP70) expression. Moreover, coixol reduced inflammatory cell recruitment and infiltration, and ameliorated pathological lung injury induced by T. gondii infection. Coixol can directly bind T.g.HSP70 or Toll-like receptor 4 (TLR4) to disrupt their interaction. Coixol prevented overexpression of inducible nitric oxide synthase, tumor necrosis factor-α, and high mobility group box 1 by inhibiting activation of the TLR4/nuclear factor (NF)-κB signaling pathway, consistent with effects of the TLR4 inhibitor CLI-095. These results indicate that coixol improves T. gondii infection-induced lung injury by interfering with T.g.HSP70-mediated TLR4/NF-κB signaling. Altogether, these findings suggest that coixol is a promising effective lead compound for the treatment of toxoplasmosis.

Toxoplasma gondii induced cognitive impairment in rats via dysregulation of dopamine receptors and indoleamine 2,3 dioxygenase

Toxoplasma gondii (T. gondii) is a parasite capable of residing in the brain of their host which influences behaviour changes due to alterations in the neurotransmitters. Consequently, dopamine receptors (DRD) and indoleamine 2, 3 dioxygenase (IDO) dysregulation facilitate the progression of behaviour changes in a host as a response to infection. This study tested the effect of neurotransmitter changes as a result of T. gondii infection on rats cognitive impairment. The T. gondii strain of type I, II and III from Malaysia were previously identified by standard procedures. Sporulated oocysts each of type I, II and III were inoculated separately into three groups of Wistar rats (n = 9) respectively. Two separate control groups received either phosphate buffered saline (PBS) or MK-801 (dizocilpine). Behaviour changes were evaluated at nine weeks post infection in a square box, elevated plus maze and gene expression level of DRD and IDO compounds. The study revealed increased fatal feline attraction, reduced anxiety, decreased DRD and increased IDO gene expression in the T. gondii infected groups and MK-801 compared to the PBS control group. In conclusion, T. gondii infection alter the level of neurotransmitters in rat which cause cognitive impairment. This implies that all the T. gondii strain can cause behaviour changes if human were infected.

Immunotherapy targeting the PD-1 pathway alleviates neuroinflammation caused by chronic Toxoplasma infection

Toxoplasma gondii can infect the host brain and trigger neuroinflammation. Such neuroinflammation might persist for years if the infection is not resolved, resulting in harmful outcomes for the brain. We have previously demonstrated the efficacy of immunotherapy targeting the programmed cell death protein 1 (PD-1) pathway on clearance of Toxoplasma tissue cysts. We aimed to test whether parasite clearance would lead to the resolution of neuroinflammation in infected brains. We established chronic Toxoplasma infection in BALB/c mice using the cyst-forming Prugniaud strain. Mice then received αPD-L1 or isotype control antibodies. After completion of the therapy, mice were euthanized six weeks later. The number of brain tissue cysts, Toxoplasma-specific CD8 + T cell proliferation and IFN-γ secretion, serum cytokine and chemokine levels, and CNS inflammation were measured. In αPD-L1-treated mice, we observed reduced brain tissue cysts, increased spleen weight, elevated IFN-γ production by antigen-specific CD8 + T cells, and a general increase in multiple serum cytokines and chemokines. Importantly, αPD-L1-treated mice displayed attenuation of meningeal lymphocytes, reactive astrocytes, and C1q expression. The reduction in inflammation-related proteins is correlated with reduced parasite burden. These results suggest that promoting systemic immunity results in parasite clearance, which in turn alleviates neuroinflammation. Our study may have implications for some brain infections where neuroinflammation is a critical component.

In vivo evaluation of anticryptosporidial effects of wheat germ extracts in immunocompromised mice

Cryptosporidium species is a prime cause of diarrheal disease in individuals with competent immunity. In patients with compromised immunity, infections are more severe particularly in developing countries. Wheat germ oil was described to have antiparasitic effect. This study was done to evaluate the possible role of wheat germ extracts in Cryptosporidium parvum (C. parvum) infected immunocompromised mice. Thirty white albino mice were classified into six groups as follow: four study groups, all immunosuppressed and infected with C. parvum oocysts. These four groups received treatments as follow: Group (I): treated with nitazoxanide. Group (II): treated with wheat germ oil. Group (III): treated with wheat germ extracted by hexane. Group (IV): treated with wheat germ extracted by ethanol. The remaining two groups were immunosuppressed control groups as follow: Group (V): only infected with C. parvum oocysts (Positive control). Group (VI): non-infected (Negative control). Stool samples were collected and examined to detect oocyst and the ileocecal region was subjected to histopathological and immunohistochemical examination. Wheat germ extracts showed a statistically significant effect against C. parvum specially wheat germ oil with P value: < 0.001, this effect was also confirmed by pathological and immunohistochemical examinations. C. parvum has an influence on human health by its effect in diarrheal disease. Wheat germ oil and its extracts has proved to be a reliable herb for C. parvum. treatment confirmed by different methodologies.

Pierre J, Xiong X, Howland JG, Josselyn SA, Frankland PW, Parkinson J. Toxoplasma infection in male mice alters dopamine-sensitive behaviors and host gene expression patterns associated with neuropsychiatric disease

During chronic infection, the single celled parasite, Toxoplasma gondii, can migrate to the brain where it has been associated with altered dopamine function and the capacity to modulate host behavior, increasing risk of neurocognitive disorders. Here we explore alterations in dopamine-related behavior in a new mouse model based on stimulant (cocaine)-induced hyperactivity. In combination with cocaine, infection resulted in heightened sensorimotor deficits and impairment in prepulse inhibition response, which are commonly disrupted in neuropsychiatric conditions. To identify molecular pathways in the brain affected by chronic T. gondii infection, we investigated patterns of gene expression. As expected, infection was associated with an enrichment of genes associated with general immune response pathways, that otherwise limits statistical power to identify more informative pathways. To overcome this limitation and focus on pathways of neurological relevance, we developed a novel context enrichment approach that relies on a customized ontology. Applying this approach, we identified genes that exhibited unexpected patterns of expression arising from the combination of cocaine exposure and infection. These include sets of genes which exhibited dampened response to cocaine in infected mice, suggesting a possible mechanism for some observed behaviors and a neuroprotective effect that may be advantageous to parasite persistence. This model offers a powerful new approach to dissect the molecular pathways by which T. gondii infection contributes to neurocognitive disorders.

Activity of isoflavone biochanin A in chronic experimental toxoplasmosis: impact on inflammation

Toxoplasma gondii is a worldwide prevalent parasite. The infection has been linked to variable inflammatory effects including neuroinflammation. Biochanin A (BCA) is an isoflavone, known for its anti-inflammatory and anti-oxidative properties. In this study, we examined the effect of BCA on the brain and liver inflammatory lesions in a murine model with chronic toxoplasmosis. Mice were divided in to six groups: non-infected control, non-infected BCA-treated, and four infected groups with Toxoplasmagondii Me49-type II cystogenic strain: infected control, BCA (50 mg/kg/day)-treated, combined BCA/cotrimoxazole-treated and cotrimoxazole (370 mg/kg/day) alone-treated. Gene expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and inducible nitric oxide synthase (iNOS) was evaluated by quantitative real-time PCR in the brain and liver tissues. In the infected control group, an upregulation of TNF-α and IL-1β mRNA expression levels was found. However, a downregulation of iNOS expression was detected in the brain of infected control mice. In both BCA- and combined-treated groups, the brain and liver tissues showed significantly reduced inflammatory lesions compared to the infected control mice with inhibited TNF-α and IL-1β mRNA levels. The iNOS expression levels in the brain tissues of BCA group were significantly higher than the levels of the infected control group. BCA alone or combined significantly reduced T. gondii cyst count in the brain tissues. In conclusion, the anti-inflammatory activity of BCA was demonstrated in the brain tissues of mice with chronic toxoplasmosis with decreased TNF-α and IL-1β expression levels and increased iNOS expression levels.

Behavioral Changes Induced by Latent Toxoplasmosis Could Arise from CNS Inflammation and Neuropathogenesis

Chronic infection with Toxoplasma gondii, a neurotropic parasite, has been linked to multiple behavioral changes in rodents and humans. The pathogenic mechanisms underlying these correlations are not known. I discuss here from animal studies the distribution of tissue cysts, the constant immune surveillance, the critical role of cyst burden, and the time-dependent consequences, which I believe are crucial to explaining the behavioral changes. In line with the brain-wide distribution of tissue cysts and chronic neuroinflammation, infected mice displayed a broad range of behavioral phenotypes. Many studies suggest that behavioral changes in mice are directly associated with tissue cyst presence or cyst burden and the host immune response. Cyst burden may not exert direct effects; however, the mechanisms causing behavioral and neuropathological changes are potentially the consequence of cyst burden over time, such as the neuroinflammation required to control the reactivation of tissue cysts. The reduction of neuroinflammation has proven that neuropathogenesis and behavioral abnormalities can be reversed, at least partially, in infected mice. Overall, Toxoplasma-induced behavioral changes are likely to be an indirect consequence of the host immune response in a parasite burden-dependent manner.

Strain-specific pre-existing immunity: A key to understanding the role of chronic Toxoplasma infection in cognition and Alzheimer's diseases?

Toxoplasma exposure can elicit cellular and humoral immune responses. In the case of chronic Toxoplasma infection, these immune responses are long-lasting. Some studies suggest that pre-existing immunity from Toxoplasma infection can shape immune responses and resistance to other pathogens and brain insults later in life. Much evidence has been generated suggesting Toxoplasma infection may contribute to cognitive impairment in the elderly. However, there have also been studies that disagree with the conclusion. Toxoplasma has many strain types, with virulence being the most notable difference. There is also considerable variation in the outcomes following Toxoplasma exposure ranging from resolved to persistent infection. Therefore, the brain microenvironment, particularly cellular constituents, differs based on the infecting strain (virulent versus hypovirulent) and infection stage (resolved versus persistent). Such difference might play a critical role in determining the outcome of the host on subsequent challengings to the brain. The ability of Toxoplasma strains to set up distinct stages for neurodegenerative pathology through varying degrees of virulence provides unique experimental tools for characterizing these pathways.

Global MicroRNAs Expression Profile Analysis Reveals Possible Regulatory Mechanisms of Brain Injury Induced by Toxoplasma gondii Infection

Toxoplasma gondii (T. gondii) is an obligate intracellular parasitic protozoan that can cause toxoplasmosis in humans and other endotherms. T. gondii can manipulate the host gene expression profile by interfering with miRNA expression, which is closely associated with the molecular mechanisms of T. gondii-induced brain injury. However, it is unclear how T. gondii manipulates the gene expression of central nervous system (CNS) cells through modulation of miRNA expression in vivo during acute and chronic infection. Therefore, high-throughput sequencing was used to investigate expression profiles of brain miRNAs at 10, 25, and 50 days post-infection (DPI) in pigs infected with the Chinese I genotype T. gondii strain in this study. Compared with the control group 87, 68, and 135 differentially expressed miRNAs (DEMs) were identified in the infected porcine brains at 10, 25, and 50 DPI, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that a large number significantly enriched GO terms and KEGG pathways were found, and were mostly associated with stimulus or immune response, signal transduction, cell death or apoptosis, metabolic processes, immune system or diseases, and cancers. miRNA–gene network analysis revealed that the crucial connecting nodes, including DEMs and their target genes, might have key roles in the interactions between porcine brain and T. gondii. These results suggest that the regulatory strategies of T. gondii are involved in the modulation of a variety of host cell signaling pathways and cellular processes, containing unfolded protein response (UPR), oxidative stress (OS), autophagy, apoptosis, tumorigenesis, and inflammatory responses, by interfering with the global miRNA expression profile of CNS cells, allowing parasites to persist in the host CNS cells and contribute to pathological damage of porcine brain. To our knowledge, this is the first report on miRNA expression profile in porcine brains during acute and chronic T. gondii infection in vivo. Our results provide new insights into the mechanisms underlying T. gondii-induced brain injury during different infection stages and novel targets for developing therapeutic agents against T. gondii.

Temporal transcriptomic changes in long non-coding RNAs and messenger RNAs involved in the host immune and metabolic response during Toxoplasma gondii lytic cycle

Background

Long non-coding RNAs (lncRNAs) are important regulators of various biological and pathological processes, in particular the inflammatory response by modulating the transcriptional control of inflammatory genes. However, the role of lncRNAs in regulating the immune and inflammatory responses during infection with the protozoan parasite Toxoplasma gondii remains largely unknown.

Methods

We performed a longitudinal RNA sequencing analysis of human foreskin fibroblast (HFF) cells infected by T. gondii to identify differentially expressed long non-coding RNAs (lncRNAs) and messenger RNAs (mRNAs), and dysregulated pathways over the course of T. gondii lytic cycle. The transcriptome data were validated by qRT-PCR.

Results

RNA sequencing revealed significant transcriptional changes in the infected HFFs. A total of 697, 1234, 1499, 873, 1466, 561, 676 and 716 differentially expressed lncRNAs (DElncRNAs), and 636, 1266, 1843, 2303, 3022, 1757, 3088 and 2531 differentially expressed mRNAs (DEmRNAs) were identified at 1.5, 3, 6, 9, 12, 24, 36 and 48 h post-infection, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of DElncRNAs and DEmRNAs revealed that T. gondii infection altered the expression of genes involved in the regulation of host immune response (e.g., cytokine–cytokine receptor interaction), receptor signaling (e.g., NOD-like receptor signaling pathway), disease (e.g., Alzheimer's disease), and metabolism (e.g., fatty acid degradation).

Conclusions

These results provide novel information for further research on the role of lncRNAs in immune regulation of T. gondii infection.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-05140-3.

Transcriptomic Analysis of the Effects of Chemokine Receptor CXCR3 Deficiency on Immune Responses in the Mouse Brain during Toxoplasma gondii Infection

The obligate intracellular parasite Toxoplasma gondii infects warm-blooded animals, including humans. We previously revealed through a whole-brain transcriptome analysis that infection with T. gondii in mice causes immune response-associated genes to be upregulated, for instance, chemokines and chemokine receptors such as CXC chemokine receptor 3 (CXCR3) and its ligand CXC chemokine ligand 10 (CXCL10). Here, we describe the effect of CXCR3 on responses against T. gondii infection in the mouse brain. In vivo assays using CXCR3-deficient mice showed that the absence of CXCR3 delayed the normal recovery of body weight and increased the brain parasite burden, suggesting that CXCR3 plays a role in the control of pathology in the brain, the site where chronic infection occurs. Therefore, to further analyze the function of CXCR3 in the brain, we profiled the gene expression patterns of primary astrocytes and microglia by RNA sequencing and subsequent analyses. CXCR3 deficiency impaired the normal upregulation of immune-related genes during T. gondii infection, in astrocytes and microglia alike. Collectively, our results suggest that the immune-related genes upregulated by CXCR3 perform a particular role in controlling pathology when the host is chronically infected with T. gondii in the brain.

Microarray profiling predicts early neurological and immune phenotypic traits in advance of CNS disease during disease progression in Trypanosoma. b. brucei infected CD1 mouse brains

Human African trypanosomiasis (HAT), also known as sleeping sickness, is a major cause of mortality and morbidity in sub-Saharan Africa. We hypothesised that recent findings of neurological features and parasite brain infiltration occurring at much earlier stages in HAT than previously thought could be explained by early activation of host genetic programmes controlling CNS disease. Accordingly, a transcriptomal analysis was performed on brain tissue at 0, 7, 14, 21 and 28dpi from the HAT CD1/GVR35 mouse model. Up to 21dpi, most parasites are restricted to the blood and lymphatic system. Thereafter the trypanosomes enter the brain initiating the encephalitic stage. Analysis of ten different time point Comparison pairings, revealed a dynamic transcriptome comprising four message populations. All 7dpi Comparisons had by far more differentially expressed genes compared to all others. Prior to invasion of the parenchyma, by 7dpi, ~2,000 genes were up-regulated, denoted [7dpi↑] in contrast to a down regulated population [7dpi↓] also numbering ~2,000. However, by 14dpi both patterns had returned to around the pre-infected levels. The third, [28dpi↑] featured over three hundred transcripts which had increased modestly up to14dpi, thereafter were significantly up-regulated and peaked at 28dpi. The fourth, a minor population, [7dpi↑-28dpi↑], had similar elevated levels at 7dpi and 28dpi. KEGG and GO enrichment analysis predicted a diverse phenotype by 7dpi with changes to innate and adaptive immunity, a Type I interferon response, neurotransmission, synaptic plasticity, pleiotropic signalling, circadian activity and vascular permeability without disruption of the blood brain barrier. This key observation is consistent with recent rodent model neuroinvasion studies and clinical reports of Stage 1 HAT patients exhibiting CNS symptoms. Together, these findings challenge the strict Stage1/Stage2 phenotypic demarcation in HAT and show that that significant neurological, and immune changes can be detected prior to the onset of CNS disease.

Toll-Like Receptor 2 is Involved in Abnormal Pregnancy in Mice Infected with Toxoplasma gondii During Late Pregnancy

Infection with Toxoplasma gondii during pregnancy causes failure of pregnancy maintenance, resulting in fetal death, abortion, stillbirth, or premature birth, but the mechanism of disease onset remains unclear. Although Toll-like receptor 2 (TLR2) is expressed on antigen-presenting cells and trophoblasts, the role of TLR2 in T. gondii infection during pregnancy is unknown. In this study, we investigated the role of TLR2 in congenital toxoplasmosis using TLR2-deficient (TLR2^−/−) mice. T. gondii infection on gestational day 12.5 (Gd12.5) induced more abnormal pregnancy, including premature birth and stillbirth, in wild-type mice than in TLR2^−/− mice. Multiple calcifications were observed in the placentas of the infected wild-type mice. At Gd18.5 (6days postinfection), the parasite numbers in the placenta and uterus and the histological changes did not differ significantly between the wild-type and TLR2^−/− mice. However, T. gondii infection reduced the mRNA expression of interleukin-12p40 (IL-12p40) and increased IL-4 and IL-10 mRNAs in the placentas of the wild-type mice. In contrast, the placentas of the TLR2^−/− mice showed no changes in the expression of these cytokines, including IL-6 and tumor necrosis factor α, in response to T. gondii infection. Serum interferon-γ levels were significantly lower in the infected TLR2^−/− mice than in the infected wild-type mice on Gd18.5. Thus, the TLR2^−/− mice were less susceptible to the induction of immune responses by T. gondii infection during late pregnancy. Therefore, TLR2 signaling may play a role in the development of disease states during pregnancy, specifically placental hypofunction.

Targeted Transcriptomic Analysis of C57BL/6 and BALB/c Mice During Progressive Chronic Toxoplasma gondii Infection Reveals Changes in Host and Parasite Gene Expression Relating to Neuropathology and Resolution

Toxoplasma gondii is a resilient parasite that infects a multitude of warm-blooded hosts and results in a lifelong chronic infection requiring continuous responses by the host. Chronic infection is characterized by a balanced immune response and neuropathology that are driven by changes in gene expression. Previous research pertaining to these processes has been conducted in various mouse models, and much knowledge of infection-induced gene expression changes has been acquired through the use of high throughput sequencing techniques in different mouse strains and post-mortem human studies. However, lack of infection time course data poses a prominent missing link in the understanding of chronic infection, and there is still much that is unknown regarding changes in genes specifically relating to neuropathology and resulting repair mechanisms as infection progresses throughout the different stages of chronicity. In this paper, we present a targeted approach to gene expression analysis during T. gondii infection through the use of NanoString nCounter gene expression assays. Wild type C57BL/6 and BALB/c background mice were infected, and transcriptional changes in the brain were evaluated at 14, 28, and 56 days post infection. Results demonstrate a dramatic shift in both previously demonstrated and novel gene expression relating to neuropathology and resolution in C57BL/6 mice. In addition, comparison between BALB/c and C57BL/6 mice demonstrate initial differences in gene expression that evolve over the course of infection and indicate decreased neuropathology and enhanced repair in BALB/c mice. In conclusion, these studies provide a targeted approach to gene expression analysis in the brain during infection and provide elaboration on previously identified transcriptional changes and also offer insights into further understanding the complexities of chronic T. gondii infection.

Transcriptomics analysis of Toxoplasma gondii-infected mouse macrophages reveals coding and noncoding signatures in the presence and absence of MyD88

BACKGROUND

Toxoplasma gondii is a globally distributed protozoan parasite that establishes life-long asymptomatic infection in humans, often emerging as a life-threatening opportunistic pathogen during immunodeficiency. As an intracellular microbe, Toxoplasma establishes an intimate relationship with its host cell from the outset of infection. Macrophages are targets of infection and they are important in early innate immunity and possibly parasite dissemination throughout the host. Here, we employ an RNA-sequencing approach to identify host and parasite transcriptional responses during infection of mouse bone marrow-derived macrophages (BMDM). We incorporated into our analysis infection with the high virulence Type I RH strain and the low virulence Type II strain PTG. Because the well-known TLR-MyD88 signaling axis is likely of less importance in humans, we examined transcriptional responses in both MyD88+/+ and MyD88-/- BMDM. Long noncoding (lnc) RNA molecules are emerging as key regulators in infection and immunity, and were, therefore, included in our analysis.

RESULTS

We found significantly more host genes were differentially expressed in response to the highly virulent RH strain rather than with the less virulent PTG strain (335 versus 74 protein coding genes for RH and PTG, respectively). Enriched in these protein coding genes were subsets associated with the immune response as well as cell adhesion and migration. We identified 249 and 83 non-coding RNAs as differentially expressed during infection with RH and PTG strains, respectively. Although the majority of these are of unknown function, one conserved lncRNA termed mir17hg encodes the mir17 microRNA gene cluster that has been implicated in down-regulating host cell apoptosis during T. gondii infection. Only a minimal number of transcripts were differentially expressed between MyD88 knockout and wild type cells. However, several immune genes were among the differences. While transcripts for parasite secretory proteins were amongst the most highly expressed T. gondii genes during infection, no differentially expressed parasite genes were identified when comparing infection in MyD88 knockout and wild type host BMDM.

CONCLUSIONS

The large dataset presented here lays the groundwork for continued studies on both the MyD88-independent immune response and the function of lncRNAs during Toxoplasma gondii infection.

Metacytofilin Is a Potent Therapeutic Drug Candidate for Toxoplasmosis

BACKGROUND

Toxoplasmosis, a parasitic disease caused by Toxoplasma gondii, is an important cause of miscarriage or adverse fetal effects, including neurological and ocular manifestations in humans. Current anti-Toxoplasma drugs have limited efficacy against toxoplasmosis and also have severe side effects. Therefore, novel efficacious drugs are urgently needed. Here, we identified metacytofilin (MCF) from a fungal Metarhizium species as a potential anti-Toxoplasma compound.

METHODS

Anti-Toxoplasma activities of MCF and its derivatives were evaluated in vitro and in vivo using nonpregnant and pregnant mice. To understand the mode of action of MCF, the RNA expression of host and parasite genes was investigated by RNAseq.

RESULTS

In vitro, MCF inhibited the viability of intracellular and extracellular T. gondii. Administering MCF intraperitoneally or orally to mice after infection with T. gondii tachyzoites increased mouse survival compared with the untreated animals. Remarkably, oral administration of MCF to pregnant mice prevented vertical transmission of the parasite. Interestingly, RNA sequencing of T. gondii-infected cells treated with MCF showed that MCF inhibited DNA replication and enhanced RNA degradation in the parasites.

CONCLUSIONS

With its potent anti-T. gondii activity, MCF is a strong candidate for future drug development against toxoplasmosis.

A multi-omic analysis of the dorsal striatum in an animal model of divergent genetic risk for alcohol use disorder

The development of selectively bred high and low alcohol-preferring mice (HAP and LAP, respectively) has allowed for an assessment of the polygenetic risk for pathological alcohol consumption and phenotypes associated with alcohol use disorder (AUD). Accumulating evidence indicates that the dorsal striatum (DS) is a central node in the neurocircuitry underlying addictive processes. Therefore, knowledge of differential gene, protein, and phosphorylated protein expression in the DS of HAP and LAP mice may foster new insights into how aberrant DS functioning may contribute to AUD-related phenotypes. To begin to elucidate these basal differences, a complementary and integrated analysis of DS tissue from alcohol-naïve male and female HAP and LAP mice was performed using RNA sequencing, quantitative proteomics, and phosphoproteomics. These datasets were subjected to a thorough analysis of gene ontology, pathway enrichment, and hub gene assessment. Analyses identified 2,108, 390, and 521 significant differentially expressed genes, proteins, and phosphopeptides, respectively between the two lines. Network analyses revealed an enrichment in the differential expression of genes, proteins, and phosphorylated proteins connected to cellular organization, cytoskeletal protein binding, and pathways involved in synaptic transmission and functioning. These findings suggest that the selective breeding to generate HAP and LAP mice may lead to a rearrangement of synaptic architecture which could alter DS neurotransmission and plasticity differentially between mouse lines. These rich datasets will serve as an excellent resource to inform future studies on how inherited differences in gene, protein, and phosphorylated protein expression contribute to AUD-related phenotypes.

Transcriptomic Profiling of Mouse Brain During Acute and Chronic Infections by Toxoplasma gondii Oocysts

Infection by the protozoan Toxoplasma gondii can have a devastating impact on the structure and function of the brain of the infected individuals, particularly immunocompromised patients. A systems biology view of the brain transcriptome can identify key molecular targets and pathways that mediate the neuropathogenesis of cerebral toxoplasmosis. Here, we performed transcriptomic analysis of the brain of mice infected by T. gondii Pru strain oocysts at 11 and 33 days post-infection (dpi) compared to uninfected (control) mice using RNA sequencing (RNA-seq). T. gondii altered the expression of 936 and 2,081 transcripts at 11 and 33 dpi, respectively, and most of these were upregulated in the infected brains. Gene Ontology (GO) enrichment and pathway analysis showed that immune response, such as interferon-gamma (IFN-γ) responsive genes were strongly affected at 11dpi. Likewise, differentially expressed transcripts (DETs) related to T cell activation, cytokine production and immune cell proliferation were significantly altered at 33 dpi. Host-parasite interactome analysis showed that some DETs were involved in immune signaling, metabolism, biosynthesis-related processes and interspecies interaction. These findings should increase knowledge of the mouse brain transcriptome and the changes in transcriptional regulation and downstream signaling pathways during acute and chronic T. gondii infections.

Comparative transcriptome analysis of normal and CD44-deleted mouse brain under chronic infection with Toxoplasma gondii

Toxoplasma gondii is a globally-distributed intracellular parasitic protozoon with wide host range. Chronic infection is the most prevalent form of T. gondii infection, which can lead to significant damage. CD44 plays an important role in body's immune response, however, little is known about the function and mechanism of CD44 in T. gondii infection until now. In the present study, total RNA isolated from four groups including C57BL/6 mouse (C57), C57BL/6△CD44 mouse(C57△CD44), C57BL/6 mouse infected with T. gondii (C57-TG) and C57BL/6△CD44 infected with T. gondii (C57△CD44-TG)were subjected to comparative transcriptome analyses using RNA-seq techniques to explore the possible function of CD44 in mouse brain during chronic Toxoplasma infection. The results indicated a total of 35,908, 54,428, 51,473 and 22,387 unigenes were annotated in KOG, Swissprot, GO and KEGG databases by transcriptome analysis, respectively, and all the databases shared 9,833 unigenes. Subsequently, differentially expressed GO terms and enriched KEGG Pathways showed 20,303 unigenes were annotated belonging to three main GO categories (namely biological process, cellular component and molecular function) and six main KEGG categories (cellular processes, environmental information processing, genetic information processing, human diseases, metabolism and organismal systems) between normal C57 and C57△CD44 mice, as well as for C57-TG and C57△CD44-TG mice. For up-regulated genes, Mid1, Ttr and Cd4 were significantly up-regulated in the C57△CD44 mouse compared with the C57 mouse, and Pcp2, Ppp1r17 and Nrk were significantly up-regulated in the C57△CD44-TG mouse compared with the C57-TG mouse. As to down-regulated genes, AC114588.1, Cbln3 and Pmch were significantly down-regulated in the C57△CD44 the mouse compared with the C57 mouse, and down-regulated genes were enriched for immunoglobulins, major histocompatibility complex (MHC) class II antigens, chemokines ligands and interferon (IFN)-inducible GTPase families in the C57△CD44-TG mouse compared with the C57-TG mouse. The present study is the first trial for exploring the function of CD44 in the mouse brain during chronic infection with T. gondii at the transcriptional level, which can provide a basis for the study of the host immune defense mechanism against T. gondii infection.

Transcriptional Profiling Suggests T Cells Cluster around Neurons Injected with Toxoplasma gondii Proteins

Like other persistent intracellular pathogens, Toxoplasma gondii, a protozoan parasite, has evolved to evade the immune system and establish a chronic infection in specific cells and organs, including neurons in the CNS. Understanding T. gondii’s persistence in neurons holds the potential to identify novel, curative drug targets. The work presented here offers new insights into the neuron-T. gondii interaction in vivo. By transcriptionally profiling neurons manipulated by T. gondii, we unexpectedly revealed that immune cells, and specifically CD8⁺ T cells, appear to cluster around these neurons, suggesting that CD8⁺ T cells specifically recognize parasite-manipulated neurons. Such a possibility supports evidence from other labs that questions the long-standing dogma that neurons are often persistently infected because they are not directly recognized by immune cells such as CD8⁺ T cells. Collectively, these data suggest we reconsider the broader role of neurons in the context of infection and neuroinflammation.

Toxoplasma gondii’s tropism for and persistence in the central nervous system (CNS) underlies the symptomatic disease that T. gondii causes in humans. Our recent work has shown that neurons are the primary CNS cell with which Toxoplasma interacts and which it infects in vivo. This predilection for neurons suggests that T. gondii’s persistence in the CNS depends specifically upon parasite manipulation of the host neurons. Yet, most work on T. gondii-host cell interactions has been done in vitro and in nonneuronal cells. We address this gap by utilizing our T. gondii-Cre system that allows permanent marking and tracking of neurons injected with parasite effector proteins in vivo. Using laser capture microdissection (LCM) and RNA sequencing using RNA-seq, we isolated and transcriptionally profiled T. gondii-injected neurons (TINs), Bystander neurons (nearby non-T. gondii-injected neurons), and neurons from uninfected mice (controls). These profiles show that TIN transcriptomes significantly differ from the transcriptomes of Bystander and control neurons and that much of this difference is driven by increased levels of transcripts from immune cells, especially CD8⁺ T cells and monocytes. These data suggest that when we used LCM to isolate neurons from infected mice, we also picked up fragments of CD8⁺ T cells and monocytes clustering in extreme proximity around TINs and, to a lesser extent, Bystander neurons. In addition, we found that T. gondii transcripts were primarily found in the TIN transcriptome, not in the Bystander transcriptome. Collectively, these data suggest that, contrary to common perception, neurons that directly interact with or harbor parasites can be recognized by CD8⁺ T cells.

IMPORTANCE Like other persistent intracellular pathogens, Toxoplasma gondii, a protozoan parasite, has evolved to evade the immune system and establish a chronic infection in specific cells and organs, including neurons in the CNS. Understanding T. gondii’s persistence in neurons holds the potential to identify novel, curative drug targets. The work presented here offers new insights into the neuron-T. gondii interaction in vivo. By transcriptionally profiling neurons manipulated by T. gondii, we unexpectedly revealed that immune cells, and specifically CD8⁺ T cells, appear to cluster around these neurons, suggesting that CD8⁺ T cells specifically recognize parasite-manipulated neurons. Such a possibility supports evidence from other labs that questions the long-standing dogma that neurons are often persistently infected because they are not directly recognized by immune cells such as CD8⁺ T cells. Collectively, these data suggest we reconsider the broader role of neurons in the context of infection and neuroinflammation.

Legionella pneumophila Infection Rewires the Acanthamoeba castellanii Transcriptome, Highlighting a Class of Sirtuin Genes

Legionella pneumophila is an environmental bacterium that has evolved to survive predation by soil and water amoebae such as Acanthamoeba castellanii, and this has inadvertently led to the ability of L. pneumophila to survive and replicate in human cells. L. pneumophila causes Legionnaire's Disease, with human exposure occurring via the inhalation of water aerosols containing both amoebae and the bacteria. These aerosols originate from aquatic biofilms found in artifical water sources, such as air-conditioning cooling towers and humidifiers. In these man-made environments, A. castellanii supports L. pneumophila intracellular replication, thereby promoting persistence and dissemination of the bacteria and providing protection from external stress. Despite this close evolutionary relationship, very little is known about how A. castellanii responds to L. pneumophila infection. In this study, we examined the global transcriptional response of A. castellanii to L. pneumophila infection. We compared A. castellanii infected with wild type L. pneumophila to A. castellanii infected with an isogenic ΔdotA mutant strain, which is unable to replicate intracellularly. We showed that A. castellanii underwent clear morphological and transcriptional rewiring over the course of L. pneumophila infection. Through improved annotation of the A. castellanii genome, we determined that these transcriptional changes primarily involved biological processes utilizing small GTPases, including cellular transport, signaling, metabolism and replication. In addition, a number of sirtuin-encoding genes in A. castellanii were found to be conserved and upregulated during L. pneumophila infection. Silencing of sirtuin gene, sir6f (ACA1_153540) resulted in the inhibition of A. castellanii cell proliferation during infection and reduced L. pneumophila replication. Overall our findings identified several biological pathways in amoebae that may support L. pneumophila replication and A. castellanii proliferation in environmental conditions.

Effects of Pseudoloma neurophilia infection on the brain transcriptome in zebrafish (Danio rerio)

Laboratory zebrafish are commonly infected with the intracellular, brain-infecting microsporidian parasite Pseudoloma neurophilia. Chronic P. neurophilia infections induce inflammation in meninges, brain and spinal cord, and have been suggested to affect neural functions since parasite clusters reside inside neurons. However, underlying neural and immunological mechanisms associated with infection have not been explored. Utilizing RNA-sequencing analysis, we found that P. neurophilia infection upregulated 175 and downregulated 45 genes in the zebrafish brain, compared to uninfected controls. Four biological pathways were enriched by the parasite, all of which were associated with immune function. In addition, 14 gene ontology (GO) terms were enriched, eight of which were associated with immune responses and five with circadian rhythm. Surprisingly, no differentially expressed genes or enriched pathways were specific for nervous system function. Upregulated immune-related genes indicate that the host generally show a pro-inflammatory immune response to infection. On the other hand, we found a general downregulation of immune response genes associated with anti-pathogen functions, suggesting an immune evasion strategy by the parasite. The results reported here provide important information on host-parasite interaction and highlight possible pathways for complex effects of parasite infections on zebrafish phenotypes.

Gasdermin-D-dependent IL-1α release from microglia promotes protective immunity during chronic Toxoplasma gondii infection

Microglia, resident immune cells of the CNS, are thought to defend against infections. Toxoplasma gondii is an opportunistic infection that can cause severe neurological disease. Here we report that during T. gondii infection a strong NF-κB and inflammatory cytokine transcriptional signature is overrepresented in blood-derived macrophages versus microglia. Interestingly, IL-1α is enriched in microglia and IL-1β in macrophages. We find that mice lacking IL-1R1 or IL-1α, but not IL-1β, have impaired parasite control and immune cell infiltration within the brain. Further, we show that microglia, not peripheral myeloid cells, release IL-1α ex vivo. Finally, we show that ex vivo IL-1α release is gasdermin-D dependent, and that gasdermin-D and caspase-1/11 deficient mice show deficits in brain inflammation and parasite control. These results demonstrate that microglia and macrophages are differently equipped to propagate inflammation, and that in chronic T. gondii infection, microglia can release the alarmin IL-1α, promoting neuroinflammation and parasite control.

Control over T. gondii infection in the brain involves microglial cells, but how these cells execute this control is not clear. Here the authors show that unlike IL-1β dominant macrophages, microglia are primed for gasdermin-D-dependent IL-1α production that is critical for protection against T. gondii infection.

Analysis of the serum peptidome associated with Toxoplasma gondii infection

Toxoplasma gondii is an obligate intracellular parasite that can cause severe disease in immunocompromised individuals and congenitally infected neonates. In order to determine whether serum peptide profile could reveal disease markers or allow determination of toxoplasmosis aggressiveness, mouse sera were collected from acutely infected, chronically infected and control subjects, and analyzed by a quantitative label-free pepdomics approach (LC-MS/MS). Six hundred and seven endogenous peptides were identified among all samples, with peptide profiling of difference that readily distinguished between acutely infected samples and other samples. Among these peptides detected in this study, 81 and 68 differentially expressed peptides (DEPs) were found in the acute and chronic infection stages, respectively. Through Gene Ontology analysis, most of the precursor proteins of these DEPs were associated with biological regulation and binding activity. These findings in this study will help in the search of peptide targets with a key role in disease diagnosis and create new opportunities for the development of better means for the prevention and control of toxoplasmosis. SIGNIFICANCE: Toxoplasma gondii is an unicellular parasite which infects humans and a wide range of warm-blooded animals. The serum peptidome contains a large set of low molecular weight endogenous peptides derived from secretion, protease activity and PTMs. In the present study we quantified the effects of T. gondii infection on the serum peptidome to identify novel disease regulated secretory factors. We developed an optimized label-free LC-MS/MS method to analyze endogenous peptides during toxoplasmosis progression. This resulted in quantification of 607 unique peptides at both acute and chronic infection stages. Collectively, our deep peptidomic analysis of serum revealed that peptide variations were affected by disease development, and peptidomics is an ideal method for quantifying changes in circulating factors on a global scale in response to pathophysiological perturbations such as T. gondii infection.

Babesia microti Confers Macrophage-Based Cross-Protective Immunity Against Murine Malaria

Malaria and babesiosis, the two primary intraerythrocytic protozoan diseases of humans, have been reported in multiple cases of co-infection in endemic regions. As the geographic range and incidence of arthropod-borne infectious diseases is being affected by climate change, co-infection cases with Plasmodium and Babesia are likely to increase. The two parasites have been used in experimental settings, where prior infection with Babesia microti has been shown to protect against fatal malarial infections in mice and primates. However, the immunological mechanisms behind such phenomena of cross-protection remain unknown. Here, we investigated the effect of a primary B. microti infection on the outcome of a lethal P. chabaudi challenge infection using a murine model. Simultaneous infection with both pathogens led to high mortality rates in immunocompetent BALB/c mice, similar to control mice infected with P. chabaudi alone. On the other hand, mice with various stages of B. microti primary infection were thoroughly immune to a subsequent P. chabaudi challenge. Protected mice exhibited decreased levels of serum antibodies and pro-inflammatory cytokines during early stages of challenge infection. Mice repeatedly immunized with dead B. microti quickly succumbed to P. chabaudi infection, despite induction of high antibody responses. Notably, cross-protection was observed in mice lacking functional B and T lymphocytes. When the role of other innate immune effector cells was examined, NK cell-depleted mice with chronic B. microti infection were also found to be protected against P. chabaudi. Conversely, in vivo macrophage depletion rendered the mice vulnerable to P. chabaudi. The above results show that the mechanism of cross-protection conferred by B. microti against P. chabaudi is innate immunity-based, and suggest that it relies predominantly upon the function of macrophages. Further research is needed for elucidating the malaria-suppressing effects of babesiosis, with a vision toward development of novel tools to control malaria.

Sialylated N-glycan profile during acute and chronic infections with Toxoplasma gondii in mice

Toxoplasma gondii is associated with physiological and psychiatric perturbations. The immune response is interrelated to the progress of anhedonia and despair symptoms of T. gondii-infected subjects. We recently reported that serum N-glycans were altered in mice displayed depressive-like behaviors. However, a novel biomarker that correlated to T. gondii infection and associated behaviors is demanded. Glycomics has been used to find affected glycoproteins during depression. The objective of this study is to investigate serum N-glycomics changes during infection with T. gondii in BALB/c mice, immunocompetent, or in severe combined immunodeficient mice, and after treatment with an immunostimulant; 1-methyl tryptophan. Glycans were examined through glycoblotting-protocol then investigated by MALDI-TOF/MS. Both depressive and sickness-related behaviors were significantly abundant (P ≤ 0.001 each), during acute T. gondii in immunocompetent mice, compared to controls. Only sickness symptoms were evident in immunodeficient mice infected with T. gondii, as associated with high expression level (P ≤ 0.001) of Peak # 15 (2 × Neu5Gc) compared to controls. The alteration of sialylated N-glycan expressions is important to detect the immune status of animals/humans against T. gondii. Moreover, 1-methyl tryptophan reduced depressive-like behavior (P ≤ 0.001) compared to controls. Therefore, sialylated N-glycan (Neu5Ac/Neu5Gc-terminal) is targeted to be used as a novel biomarker of sickness/depressive-like behaviors.

A Transcriptome Analysis: Various Reasons of Adverse Pregnancy Outcomes Caused by Acute Toxoplasma gondii Infection

Background

Toxoplasma gondii (T. gondii) is an obligate intracellular parasite, which can affect the pregnancy outcomes in infected females by damaging the uterus, and the intrauterine environment as well as and the hypothalamus resulting in hormonal imbalance. However, the molecular mechanisms underlying the parasite-induced poor pregnancy outcomes and the key genes regulating these mechanisms remain unclear. Therefore, this study aimed to analyze the gene expression in the mouse’s uterus following experimentally-induced acute infection with T. gondii RH strain. Three groups of female mice were intraperitoneally injected with tachyzoites as follow; 3 days before pregnancy (FBD6), after pregnancy (FAD6), and after implantation (FID8) as the experimental groups. Another corresponding three groups served as control, were injected with normal saline at the same time. Transcriptome analysis of the total RNA extracted from both infected and non-infected mouse uterus samples was performed using RNA sequencing (RNA-Seq).

Results

The three experimental groups (FBD6, FAD6, and FID8) had a total of 4,561, 2,345, and 2,997 differentially expressed genes (DEGs) compared to the controls. The significantly upregulated and downregulated DEGs were 2,571 and 1,990 genes in FBD6, 1,042 and 1,303 genes in FAD6 and 1,162 and 1,835 genes in FID8 group, respectively. The analysis of GO annotation, and KEGG pathway showed that DEGs were mainly involved in anatomical structure development, transport, cell differentiation, embryo development, hormone biosynthetic process, signal transduction, immune system process, phagosome, pathways in cancer, and cytokine-cytokine receptor interaction pathways.

Conclusion

T. gondii infection can induce global transcriptomic changes in the uterus that may cause pregnancy hypertension, destruct the intrauterine environment, and hinder the normal development of placenta and embryo. Our results may help to understand the molecular mechanisms of the acute T. gondii infection, which could promote the development of new therapeutics or prophylactics for toxoplasmosis in pregnancy.

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.

Neuroinflammation-Associated Aspecific Manipulation of Mouse Predator Fear by Toxoplasma gondii

In rodents, the decrease of felid aversion induced by Toxoplasma gondii, a phenomenon termed fatal attraction, is interpreted as an adaptive manipulation by the neurotropic protozoan parasite. With the aim of understanding how the parasite induces such specific behavioral modifications, we performed a multiparametric analysis of T. gondii-induced changes on host behavior, physiology, and brain transcriptome as well as parasite cyst load and distribution. Using a set of complementary behavioral tests, we provide strong evidence that T. gondii lowers general anxiety in infected mice, increases explorative behaviors, and surprisingly alters predator aversion without selectivity toward felids. Furthermore, we show a positive correlation between the severity of the behavioral alterations and the cyst load, which indirectly reflects the level of inflammation during brain colonization. Taken together, these findings refute the myth of a selective loss of cat fear in T. gondii-infected mice and point toward widespread immune-related alterations of behaviors.

What a Difference 30 Years Makes! A Perspective on Changes in Research Methodologies Used to Study Toxoplasma gondii

Toxoplasma gondii is a remarkable species with a rich cell, developmental, and population biology. It is also sometimes responsible for serious disease in animals and humans and the stages responsible for such disease are relatively easy to study in vitro or in laboratory animal models. As a result of all this, Toxoplasma has become the subject of intense investigation over the last several decades, becoming a model organism for the study of the phylum of which it is a member, Apicomplexa. This has led to an ever-growing number of investigators applying an ever-expanding set of techniques to dissecting how Toxoplasma "ticks" and how it interacts with its many hosts. In this perspective piece I first wind back the clock 30 years and then trace the extraordinary pace of methodologies that have propelled the field forward to where we are today. In keeping with the theme of this collection, I focus almost exclusively on the parasite, rather than host side of the equation. I finish with a few thoughts about where the field might be headed-though if we have learned anything, the only sure prediction is that the pace of technological advance will surely continue to accelerate and the future will give us still undreamed of methods for taking apart (and then putting back together) this amazing organism with all its intricate biology. We have so far surely just scratched the surface.

Transcriptome analysis of the effect of C-C chemokine receptor 5 deficiency on cell response to Toxoplasma gondii in brain cells

BACKGROUND

Infection with Toxoplasma gondii is thought to damage the brain and be a risk factor for neurological and psychotic disorders. The immune response-participating chemokine system has recently been considered vital for brain cell signaling and neural functioning. Here, we investigated the effect of the deficiency of C-C chemokine receptor 5 (CCR5), which is previously reported to be associated with T. gondii infection, on gene expression in the brain during T. gondii infection and the relationship between CCR5 and the inflammatory response against T. gondii infection in the brain.

RESULTS

We performed a genome-wide comprehensive analysis of brain cells from wild-type and CCR5-deficient mice. Mouse primary brain cells infected with T. gondii were subjected to RNA sequencing. The expression levels of some genes, especially in astrocytes and microglia, were altered by CCR5-deficiency during T. gondii infection, and the gene ontology and Kyoto Encyclopedia of Genes and Genomes analysis revealed an enhanced immune response in the brain cells. The expression levels of genes which were highly differentially expressed in vitro were also investigated in the mouse brains during the T. gondii infections. Among the genes tested, only Saa3 (serum amyloid A3) showed partly CCR5-dependent upregulation during the acute infection phase. However, analysis of the subacute phase showed that in addition to Saa3, Hmox1 may also contribute to the protection and/or pathology partly via the CCR5 pathway.

CONCLUSIONS

Our results indicate that CCR5 is involved in T. gondii infection in the brain where it contributes to inflammatory responses and parasite elimination. We suggest that the inflammatory response by glial cells through CCR5 might be associated with neurological injury during T. gondii infection to some extent.

Involvement of Toll-like receptor 2 in the cerebral immune response and behavioral changes caused by latent Toxoplasma infection in mice

Subacute and chronic infections with the intracellular protozoan parasite Toxoplasma gondii are associated with an increased risk of psychiatric diseases like schizophrenia. However, little is known about the mechanisms involved in T. gondii-induced neuronal disorders. Recently, we reported that Toll-like receptor 2 (TLR2) was required to initiate the innate immune response in cultured mouse brain cells. However, how TLR2 contributes to latent infection with T. gondii remains unclear. Therefore, we examined the role of TLR2 in brain pathology and behavior using wild-type (TLR2^+/+) and TLR2-deficient (TLR2^-/-) mice. The behavioral analyses showed that TLR2 deficiency increased the anxiety state of the uninfected and infected animals alike, and TLR2 deficiency showed no relationship with the infection. In the contextual and cued fear-conditioning tests, T. gondii infection decreased the mouse freezing reaction while TLR2 deficiency increased it, but there was no interaction between the two factors. Our histopathological analysis showed that the TLR2^+/+ and TLR2^-/- mice had similar brain lesions at 30 days post infection (dpi) with T. gondii. Higher numbers of parasites were detected in the brains of the TLR2^-/- mice than in those from the TLR2^+/+ mice at 30 dpi, but not at 7 and 14 dpi. No significant differences were observed in the proinflammatory gene expression levels in the TLR2^+/+ and TLR2^-/- mice. Therefore, it appears that TLR2 signaling in the brain might contribute to the control of parasite growth, but not to brain pathology or the impaired fear memory response induced by infection with T. gondii.

Metabolomic signature of mouse cerebral cortex following Toxoplasma gondii infection

BACKGROUND

The protozoan parasite Toxoplasma gondii infects and alters the neurotransmission in cerebral cortex and other brain regions, leading to neurobehavioral and neuropathologic changes in humans and animals. However, the molecules that contribute to these changes remain largely unknown.

METHODS

We have investigated the impact of T. gondii infection on the overall metabolism of mouse cerebral cortex. Mass-spectrometry-based metabolomics and multivariate statistical analysis were employed to discover metabolomic signatures that discriminate between cerebral cortex of T. gondii-infected and uninfected control mice.

RESULTS

Our results identified 73, 67 and 276 differentially abundant metabolites, which were involved in 25, 37 and 64 pathways at 7, 14 and 21 days post-infection (dpi), respectively. Metabolites in the unsaturated fatty acid biosynthesis pathway were upregulated as the infection progressed, indicating that T. gondii induces the biosynthesis of unsaturated fatty acids to promote its own growth and survival. Some of the downregulated metabolites were related to pathways, such as steroid hormone biosynthesis and arachidonic acid metabolism. Nine metabolites were identified as T. gondii responsive metabolites, namely galactosylsphingosine, arachidonic acid, LysoSM(d18:1), L-palmitoylcarnitine, calcitetrol, 27-Deoxy-5b-cyprinol, L-homophenylalanine, oleic acid and ceramide (d18:1/16:0).

CONCLUSIONS

Our data provide novel insight into the dysregulation of the metabolism of the mouse cerebral cortex during T. gondii infection and have important implications for studies of T. gondii pathogenesis.

Anti-Toxoplasma activity of silver nanoparticles green synthesized with Phoenix dactylifera and Ziziphus spina-christi extracts which inhibits inflammation through liver regulation of cytokines in Balb/c mice

Toxoplasmosis constitutes a global infection caused by oblige intracellular apicomplexan protozoan parasite Toxoplasma gondii Although often asymptomatic, infection can result in more severe, potentially life threatening symptoms particularly in immunocompromised individuals. The present study evaluated the anti-Toxoplasma effects in experimental animals of silver nanoparticles synthesized in combination with extracts of natural plants (Phoenix dactylifera and Ziziphus spina-christi) as an alternative method to standard sulfadiazine drug therapy. Liver functions estimated by and AST and ALT were significantly increased in T. gondii-infected mice compared with the control group as well as hepatic nitric oxide (NO), lipid peroxidation (LPO) levels and caused significant decrease in superoxide dismutase (SOD), catalase (CAT) and glutathione activities in the liver homogenates. Nanoparticles pretreatment prevented liver damage as determined by enzyme activity inhibition, in addition to significant inhibition of hepatic NO levels and significant elevation in liver SOD and CAT activities. Moreover, nanoparticle treatment significantly decreased hepatic LPO and NO concentrations and proinflammatory cytokines but significantly boosted the antioxidant enzyme activity of liver homogenate. In addition, histological examinations showed distinct alterations in the infected compared with untreated control groups. Conversely, nanoparticles pretreatment showed improvement in the histological features indicated by slight infiltration and fibrosis, minimal pleomorphism and less hepatocyte and degeneration. Furthermore, nanoparticles treatment induced a reduction in immunoreactivity to TGF-β and NF-κB in hepatic tissues. Therefore, the present study provides new insights into various natural plants that are used traditionally for the treatment of toxoplasmosis and other parasitic infections, which may be useful as alternative treatment option for T. gondii infections.

An Overview of Peripheral Blood Mononuclear Cells as a Model for Immunological Research of Toxoplasma gondii and Other Apicomplexan Parasites

In biology, models are experimental systems meant to recreate aspects of diseases or human tissue with the goal of generating inferences and approximations that can contribute to the resolution of specific biological problems. Although there are many models for studying intracellular parasites, their data have produced critical contradictions, especially in immunological assays. Peripheral blood mononuclear cells (PBMCs) represent an attractive tissue source in pharmacogenomics and in molecular and immunologic studies, as these cells are easily collected from patients and can serve as sentinel tissue for monitoring physiological perturbations due to disease. However, these cells are a very sensitive model due to variables such as temperature, type of stimulus and time of collection as part of posterior processes. PBMCs have been used to study Toxoplasma gondii and other apicomplexan parasites. For instance, this model is frequently used in new therapies or vaccines that use peptides or recombinant proteins derived from the parasite. The immune response to T. gondii is highly variable, so it may be necessary to refine this cellular model. This mini review highlights the major approaches in which PBMCs are used as a model of study for T. gondii and other apicomplexan parasites. The variables related to this model have significant implications for data interpretation and conclusions related to host-parasite interaction.

Downregulation of the Central Noradrenergic System by Toxoplasma gondii Infection

Toxoplasma gondii is associated with physiological effects in the host. Dysregulation of catecholamines in the central nervous system has previously been observed in chronically infected animals. In the study described here, the noradrenergic system was found to be suppressed with decreased levels of norepinephrine (NE) in brains of infected animals and in infected human and rat neural cells in vitro The mechanism responsible for the NE suppression was found to be downregulation of dopamine β-hydroxylase (DBH) gene expression, encoding the enzyme that synthesizes norepinephrine from dopamine, with downregulation observed in vitro and in infected brain tissue, particularly in the dorsal locus coeruleus/pons region. The downregulation was sex specific, with males expressing reduced DBH mRNA levels whereas females were unchanged. Rather, DBH expression correlated with estrogen receptor in the female rat brains for this estrogen-regulated gene. DBH silencing was not a general response of neurons to infection, as human cytomegalovirus did not downregulate DBH expression. The noradrenergic-linked behaviors of sociability and arousal were altered in chronically infected animals, with a high correlation between DBH expression and infection intensity. A decrease in DBH expression in noradrenergic neurons can elevate dopamine levels, which provides a possible explanation for mixed observations of changes in this neurotransmitter with infection. Decreased NE is consistent with the loss of coordination and motor impairments associated with toxoplasmosis. Further, the altered norepinephrine synthesis observed here may, in part, explain behavioral effects of infection and associations with mental illness.

Acute Toxoplasma Gondii Infection in Cats Induced Tissue-Specific Transcriptional Response Dominated by Immune Signatures

RNA-sequencing was used to detect transcriptional changes in six tissues of cats, seven days after T. gondii infection. A total of 737 genes were differentially expressed (DEGs), of which 410 were up-regulated and 327 were down-regulated. The liver exhibited 151 DEGs, lung (149 DEGs), small intestine (130 DEGs), heart (123 DEGs), brain (104 DEGs), and spleen (80 DEGs)-suggesting tissue-specific transcriptional patterns. Gene ontology and KEGG analyses identified DEGs enriched in immune pathways, such as cytokine-cytokine receptor interaction, Jak-STAT signaling pathway, NOD-like receptor signaling pathway, NF-kappa B signaling pathway, MAPK signaling pathway, T cell receptor signaling pathway, and the cytosolic DNA sensing pathway. C-X-C motif chemokine 10 (CXCL10) was involved in most of the immune-related pathways. PI3K/Akt expression was down-regulated in all tissues, except the spleen. The genes for phosphatase, indoleamine 2,3-dioxygenase, Hes Family BHLH Transcription Factor 1, and guanylate-binding protein 5, playing various roles in immune defense, were co-expressed across various feline tissues. Multivariate K-means clustering analysis produced seven gene clusters featuring similar gene expression patterns specific to individual tissues, with lung tissue cluster having the largest number of DEGs. These findings suggest the presence of a broad immune defense mechanism across various tissues in cats against acute T. gondii infection.

Neospora caninum Dense Granule Protein 7 Regulates the Pathogenesis of Neosporosis by Modulating Host Immune Response

Neospora caninum is a protozoan parasite closely related to Toxoplasma gondii Neosporosis caused by N. caninum is considered one of the main causes of abortion in cattle and nervous-system dysfunction in dogs, and identification of the virulence factors of this parasite is important for the development of control measures. Here, we used a luciferase reporter assay to screen the dense granule proteins genes of N. caninum, and we found that NcGRA6, NcGRA7, and NcGRA14 are involved in the activation of the NF-κB, calcium/calcineurin, and cAMP/PKA signals. To analyze the functions of these proteins and Neospora cyclophilin, we successfully knocked out their genes in the Nc1 strain using plasmids containing the CRISPR/Cas9 components. Among the deficient lines, the NcGRA7-deficient parasites showed reduced virulence in mice. An RNA sequencing analysis of infected macrophage cultures showed that NcGRA7 mainly regulates the host cytokine and chemokine production. The levels of gamma interferon in the ascites fluid, CXCL10 expression in the peritoneal cells, and CCL2 expression in the spleen were lower 5 days after infection with the NcGRA7-deficient parasite than after infection with the parental strain. The parasite burden and the degree of necrosis in the brains of mice infected with the NcGRA7-deficient parasite were also lower than in those of the parental strain. Collectively, our data suggest that both the NcGRA7-dependent activation of the inflammatory response and the parasite burden are important in Neospora virulence.IMPORTANCENeospora caninum invades and replicates in a broad range of host species and cells within those hosts. The effector proteins exported by Neospora induce its pathogenesis by modulating the host immunity. We show that most of the transcriptomic effects in N. caninum-infected cells depend upon the activity of NcGRA7. A deficiency in NcGRA7 reduced the virulence of the parasite in mice. This study demonstrates the importance of NcGRA7 in the pathogenesis of neosporosis.

Targeting of RNA Polymerase II by a nuclear Legionella pneumophila Dot/Icm effector SnpL

The intracellular pathogen Legionella pneumophila influences numerous eukaryotic cellular processes through the Dot/Icm-dependent translocation of more than 300 effector proteins into the host cell. Although many translocated effectors localise to the Legionella replicative vacuole, other effectors can affect remote intracellular sites. Following infection, a subset of effector proteins localises to the nucleus where they subvert host cell transcriptional responses to infection. Here, we identified Lpw27461 (Lpp2587), Lpg2519 as a new nuclear-localised effector that we have termed SnpL. Upon ectopic expression or during L. pneumophila infection, SnpL showed strong nuclear localisation by immunofluorescence microscopy but was excluded from nucleoli. Using immunoprecipitation and mass spectrometry, we determined the host-binding partner of SnpL as the eukaryotic transcription elongation factor, Suppressor of Ty5 (SUPT5H)/Spt5. SUPT5H is an evolutionarily conserved component of the DRB sensitivity-inducing factor complex that regulates RNA Polymerase II dependent mRNA processing and transcription elongation. Protein interaction studies showed that SnpL bound to the central Kyprides, Ouzounis, Woese motif region of SUPT5H. Ectopic expression of SnpL led to massive upregulation of host gene expression and macrophage cell death. The activity of SnpL further highlights the ability of L. pneumophila to control fundamental eukaryotic processes such as transcription that, in the case of SnpL, leads to global upregulation of host gene expression.

Transcriptome profiling provides gene resources for understanding gill immune responses in Japanese flounder (Paralichthys olivaceus) challenged with Edwardsiella tarda

Marine organisms are commonly under threats from various pathogens. Edwardsiella tarda is one of the fish pathogens that seriously infect cultured and wild fish species. Bacteremia caused by E. tarda can be a fatal disease in humans. Fish gill is a mucosa-associated lymphoid tissue that directly contacted with sea water. Generating gill transcriptomic resources that challenged by E. tarda is crucial for understanding the molecular mechanisms underlying gill immune responses. In this study, we performed transcriptome profiling of gene expression in Japanese flounder gills (Paralichthys olivaceus) challenged by E. tarda with different stress duration. An average of 40 million clean reads per library were obtained, of which approximately 83.2% were successfully mapped to the reference genome. 456 and 1037 differential expressed genes (DEGs) were identified at 8 h and 48 h post-injection, respectively. Gene annotation analysis and protein-protein interaction networks were conducted to obtain the key interaction relationships of immune-related DEGs during pathogens infection. 24 hub genes with multiple protein-protein interaction relationships or involved in multiple KEGG signaling pathways were discovered and validated by qRT-PCR. These hub genes mainly participated in Leukocyte transendothelial migration signaling pathway, B cell receptor signaling pathway, Wnt signaling pathway and Apoptosis signaling pathway. This study represents the first gill transcriptomic analysis based on protein-protein interaction networks in fish and provides valuable gene resources for understanding the fish gill immunity, which can pave the way to understand the molecular mechanisms of immune responses with E. tarda infection.

Transcriptome profiling based on protein-protein interaction networks provides a core set of genes for understanding blood immune response mechanisms against Edwardsiella tarda infection in Japanese flounder (Paralichthys olivaceus)

Marine organisms are commonly under threat from various pathogens. Edwardsiella tarda is one of the fish pathogens that can infect both cultured and wild fish species. E. tarda can also infect other vertebrates, including amphibians, reptiles, and mammals. Bacteremia caused by E. tarda can be a fatal disease in humans. Blood acts as a pipeline for the fish immune system. Generating blood transcriptomic resources from fish challenged by E. tarda is crucial for understanding molecular mechanisms underlying blood immune response process. In this study, we performed transcriptome-wide gene expression profiling of Japanese flounder (Paralichthys olivaceus) challenged by 8 and 48 h E. tarda stress. An average of 37 million clean reads per library was obtained, and approximately 85.6% of these reads were successfully mapped to the reference genome. In addition, 808 and 1265 differential expression genes (DEGs) were found at 8 and 48 h post-injection, respectively. Gene Ontology (GO) functional enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were conducted to search immune-related DEGs. A protein-protein interaction network was constructed to obtain the interaction relationship of immune genes during pathogens stress. Based on KEGG and protein association networks analysis, 30 hub genes were discovered and validated by quantitative RT-PCR. This study represents the first transcriptome analysis based on protein-protein interaction networks in fish and provides us with valuable gene resources for the research of fish blood immunity, which can significantly assist us to further understand the molecular mechanisms of humans and other vertebrates against E. tarda.

Toxoplasma Gondii Exposure and Neurological Disorders: An Age- and Gender-Matched Case-Control Pilot Study

Little is known about the association of Toxoplasma gondii infection and neurological disorders. We performed a case-control study with 344 patients with neurological diseases and 344 neurologically healthy age- and gender-matched subjects. Sera of participants were analyzed for anti-T. gondii IgG and IgM antibodies using commercially available immunoassays. Anti-T. gondii IgG antibodies were detected in 25 (7.3%) cases and in 35 (10.2%) controls (odds ratio [OR] = 0.69; 95% confidence interval [CI]: 0.40-1.18; P = 0.17). Anti-T. gondii IgM antibodies were found in 5 (14.3%) of the 25 IgG seropositive cases and in 13 (37.1°%) of the 35 IgG seropositive controls (P = 0.15). Anti-T. gondii IgG antibodies were found in 8 (3.8%) of 213 female cases and in 23 (10.8%) of 213 female controls (OR = 0.32; 95% CI: 0.14-0.73; P = 0.005); and in 17 (13.0%) of 131 male cases and in 12 (9.2%) of 131 male controls (P = 0.32). No direct association between IgG seropositivity and specific neurological disorders was detected. We found no support for a role of latent T. gondii infection in the risk for neurological disorders in this setting. With respect to specific neurological disorders, further studies using larger patient cohorts will be required.