Toxoplasma gondii infection induces lipid metabolism alterations in the murine host

Impact of Toxoplasma gondii infection on TM3 Leydig cells: Alterations in testosterone and cytokines levels

Leydig cells play pivotal roles in eliciting male characteristics by producing testosterone and any damage to these cells can compromise male fertility Toxoplasma gondii (T. gondii) is an intracellular parasite capable to invade any nucleated cell, including cells from male reproductive system. Herein, we evaluated the capacity of RH strain of T. gondii to infect TM3 Leydig cells and the impact of this infection on testosterone and inflammatory mediators production. We first, by performing adherence, infection, and intracellular proliferation assays, we found a significant increase in the number of infected Leydig cells, peaking 48 h after the infection with T. gondii. Supernatants of TM3 infected cells exhibited, in a time-dependent manner, increased levels of testosterone as well as monocyte chemoattractant protein-1 (MCP-1) and interferon-γ (IFN-γ), which is correlated with the robust T. gondii infection. In conclusion, our study provides new insights regarding the harmful effects of T. gondii infection on male reproductive system.

The influence of exposure to Toxoplasma Gondii on host lipid metabolism

BACKGROUND

Mounting evidence suggested a complex correlation between host lipid metabolism and Toxoplasma gondii (T. gondii) infection. However, the inherent association between T. gondii infection and host lipid state remains elusive either in mice or in human hosts.

METHODS

Through a study in a sample of 1045 healthy participants from eastern China, we determined the association of T. gondii infection and host lipid levels using serological methods. We then examined the host lipid levels in C57BL/6 J mice at both acute and chronic T. gondii infection stages (for a period up to 36 weeks post infection).

RESULTS

In our case-control study, T. gondii seropositive individuals had higher low-density lipoproteins (LDL) (P = 0.0043) and total cholesterol (TC) (P = 0.0134) levels compared to seronegative individuals. Furthermore, individuals with LDL (OR = 3.25; 95% CI:1.60-6.61) and TC (OR = 2.10; 95% CI:1.22-3.63) levels above the upper limit of normal range had higher odds ratio to be T. gondii IgG positive. Consistently, in vivo data revealed that a significantly increased LDL level was first observed at early acute stage but plateaued to later time (chronic infection with T. gondii).

CONCLUSIONS

In both healthy population and T. gondii-infected mice, seropositive individuals had higher LDL level. Individuals with positive T. gondii IgG had more odds of being with LDL and TC abnormality. Latent T. gondii infection is common worldwide, potential medical interventions to host lipid metabolism may be a breakthrough point to the prevention and control of this parasite infection.

Latent Toxoplasma gondii infection is associated with decreased serum triglyceride to high-density lipoprotein cholesterol ratio in male patients with schizophrenia

BACKGROUND

Previous studies suggested a complex association between Toxoplasma gondii (TG) infection and host lipid metabolism. Both TG infection and metabolic disturbances are very common in patients with schizophrenia, but this relationship is not clear.

METHODS

In this cross-sectional study, we evaluated the association between TG seropositivity, serum lipid levels, body mass index (BMI) and metabolic syndrome (MetS) in 210 male inpatients with schizophrenia.

RESULTS

In our sample of schizophrenia patients, with the mean age of 43.90 ± 12.70 years, the rate of TG seropositivity was 52.38% and the prevalence of MetS was 17%. Patients with the TG antibodies had lower serum triglyceride levels and body weight compared to TG seronegative patients, despite having more frequently received antipsychotics (clozapine, olanzapine risperidone and quetiapine), which are well known to induce weight gain and metabolic abnormalities. However, the only significant change in metabolic parameters, observed in TG seropositive patients with schizophrenia, was decreased serum triglyceride to high-density lipoprotein cholesterol (HDL-C) ratio. No associations were observed between TG seropositivity and serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and glucose levels, waist circumference, BMI and the rate of MetS.

CONCLUSION

This is the first report of the association between TG infection and decreased serum triglyceride to HDL-C ratio in a sample of carefully selected men with chronic schizophrenia.

Evidence for host genetic regulation of altered lipid metabolism in experimental toxoplasmosis supported with gene data mining results

Toxoplasma gondii is one of the most successful parasites on Earth, infecting a wide array of mammals including one third of the global human population. The obligate intracellular protozoon is not capable of synthesizing cholesterol (Chl), and thus depends on uptake of host Chl for its own development. To explore the genetic regulation of previously observed lipid metabolism alterations during acute murine T. gondii infection, we here assessed total Chl and its fractions in serum and selected tissues at the pathophysiological and molecular level, and integrated the observed gene expression of selected molecules relevant for Chl metabolism, including its biosynthetic and export KEGG pathways, with the results of published transcriptomes obtained in similar murine models of T. gondii infection. The serum lipid status as well as the transcript levels of relevant genes in the brain and the liver were assessed in experimental models of acute and chronic toxoplasmosis in wild-type mice. The results showed that acute infection was associated with a decrease in Chl content in both the liver and periphery (brain, peripheral lymphocytes), and a decrease in Chl reverse transport. In contrast, in chronic infection, a return to normal levels of Chl metabolism has been noted. These changes corresponded to the brain and liver gene expression results as well as to data obtained via mining. We propose that the observed changes in Chl metabolism are part of the host defense response. Further insight into the lipid metabolism in T. gondii infection may provide novel targets for therapeutic agents.

Toxoplasmosis--a global threat. Correlation of latent toxoplasmosis with specific disease burden in a set of 88 countries

BACKGROUND

Toxoplasmosis is becoming a global health hazard as it infects 30-50% of the world human population. Clinically, the life-long presence of the parasite in tissues of a majority of infected individuals is usually considered asymptomatic. However, a number of studies show that this 'asymptomatic infection' may also lead to development of other human pathologies.

AIMS OF THE STUDY

The purpose of the study was to collect available geoepidemiological data on seroprevalence of toxoplasmosis and search for its relationship with mortality and disability rates in different countries.

METHODS AND FINDINGS

Prevalence data published between 1995-2008 for women in child-bearing age were collected for 88 countries (29 European). The association between prevalence of toxoplasmosis and specific disease burden estimated with age-standardized Disability Adjusted Life Year (DALY) or with mortality, was calculated using General Linear Method with Gross Domestic Product per capita (GDP), geolatitude and humidity as covariates, and also using nonparametric partial Kendall correlation test with GDP as a covariate. The prevalence of toxoplasmosis correlated with specific disease burden in particular countries explaining 23% of variability in disease burden in Europe. The analyses revealed that for example, DALY of 23 of 128 analyzed diseases and disease categories on the WHO list showed correlations (18 positive, 5 negative) with prevalence of toxoplasmosis and another 12 diseases showed positive trends (p<0.1). For several obtained significant correlations between the seroprevalence of toxoplasmosis and specific diseases/clinical entities, possible pathophysiological, biochemical and molecular explanations are presented.

CONCLUSIONS

The seroprevalence of toxoplasmosis correlated with various disease burden. Statistical associations does not necessarily mean causality. The precautionary principle suggests however that possible role of toxoplasmosis as a triggering factor responsible for development of several clinical entities deserves much more attention and financial support both in everyday medical practice and future clinical research.

Strain specific transcriptional response in Mycobacterium tuberculosis infected macrophages

Background

Tuberculosis (TB), a bacterial infection caused by Mycobacterium tuberculosis (Mtb) remains a significant health problem worldwide with a third of the world population infected and nearly nine million new cases claiming 1.1 million deaths every year. The outcome following infection by Mtb is determined by a complex and dynamic host-pathogen interaction in which the phenotype of the pathogen and the immune status of the host play a role. However, the molecular mechanism by which Mtb strains induce different responses during intracellular infection of the host macrophage is not fully understood. To explore the early molecular events triggered upon Mtb infection of macrophages, we studied the transcriptional responses of murine bone marrow-derived macrophages (BMM) to infection with two clinical Mtb strains, CDC1551 and HN878. These strains have previously been shown to differ in their virulence/immunogenicity in the mouse and rabbit models of pulmonary TB.

Results

In spite of similar intracellular growth rates, we observed that compared to HN878, infection by CDC1551 of BMM was associated with an increased global transcriptome, up-regulation of a specific early (6 hours) immune response network and significantly elevated nitric oxide production. In contrast, at 24 hours post-infection of BMM by HN878, more host genes involved in lipid metabolism, including cholesterol metabolism and prostaglandin synthesis were up-regulated, compared to infection with CDC1551.

In association with the differences in the macrophage responses to infection with the 2 Mtb strains, intracellular CDC1551 expressed higher levels of stress response genes than did HN878.

Conclusions

In association with the early and more robust macrophage activation, intracellular CDC1551 cells were exposed to a higher level of stress leading to increased up-regulation of the bacterial stress response genes. In contrast, sub-optimal activation of macrophages and induction of a dysregulated host cell lipid metabolism favored a less stressful intracellular environment for HN878. Our findings suggest that the ability of CDC1551 and HN878 to differentially activate macrophages during infection probably determines their ability to either resist host cell immunity and progress to active disease or to succumb to the host protective responses and be driven into a non-replicating latent state in rabbit lungs.