Neurophysiological Changes Induced by Chronic Toxoplasma gondii Infection

Type-1 diabetes mellitus down-regulated local cerebral glial fibrillary acidic protein expression in experimental toxoplasmosis

Cerebral toxoplasmosis is an opportunistic infection, occurring mostly in immunosuppressed patients due to the reactivation of latent Toxoplasma cysts. The cerebral comorbidity in diabetic patients tends to intensify the burden of pathogenic infection within the brain. The aim of this work was to study the effect of cerebral toxoplasmosis in experimentally infected hyperglycemic mice, on histopathology and glial fibrillary acidic protein (GFAP) expression, compared to normoglycemic mice at different time intervals. Vasculopathy was exclusively observed in diabetic groups, with features of increased severity during Toxoplasma infection. Gliosis was observed in diabetic groups, while hyperactive astroglial activity was detected in normoglycemic groups, especially at 6 weeks of infection. GFAP expression showed significant up-regulation in normoglycemic mice at 6 weeks of infection (40.03 ± 1.41) afterwards, it decreased to 22.22 ± 3.14 at 12 weeks which was statistically insignificant to the normal level, possibly indicating the successful Toxoplasma stage transformation (to bradyzoite), thereby limiting the infection within the brain. In hyperglycemic infected groups, GFAP was significantly down-regulated, in both acute and chronic phases of infection, most likely indicating failure of stage transformation and infection limitation. This may expose those vulnerable groups to the risk of dissemination, resulting in life-threatening diffuse encephalitis. The current study emphasized the importance of rapid diagnosis of Toxoplasma infection in diabetic subjects, and highlighted the value of using GFAP as a neurological indicator of disease progression in those comorbid cases.

Association of infection with Toxoplasma gondii and Toxocara on cognitive function among US adults aged 60 and over, NHANES 2011-2014

BACKGROUND

Toxoplasma gondii and Toxocara are common parasites that infect humans globally. Our aim was to examine the relationship between T. gondii and Toxocara infection and cognition.

METHODS

Multivariate logistic regression was used to test the association of T. gondii and Toxocara seropositivity on indices of cognitive function (a word list learning trial with delayed recall from the Consortium to Establish a Registry for Alzheimer's Disease, an animal fluency test (AFT) and a digit symbol substitution test (DSST)) among 2643 adults aged 60 years and older in the 2011-2014 National Health and Nutrition Examination Survey.

RESULTS

Seropositivity to T. gondii or Toxocara were both associated with lower scores in all three cognitive function measures examined in univariate analyses. Except for the DSST, these associations were not significant after adjustment for age, gender, race and Hispanic origin, poverty level, education, US birth status, depression and hypertension. On stratification to account for significant interactions, Toxocara seropositivity was associated with worse scores on the AFT among those born outside the USA, worse scores on the DSST among those aged 60-69 years, female, Hispanic and with a high school diploma or less. Lower DSST scores with Toxocara infection was greater for adults living below compared with at or above the poverty level.

CONCLUSIONS

Seropositivity to these parasites, particularly to Toxocara, may be associated with diminished cognitive performance in certain subgroups of older adults.

Curcumin ameliorates chronic Toxoplasma gondii infection-induced affective disorders through modulation of proinflammatory cytokines and oxidative stress

Objectives

Long-term infection with Toxoplasma gondii is associated with affective disorders (i.e., anxiety and depression) in adults. We aimed to explore the effects of curcumin (CR) on anxiety- and depressive-like behaviors in mice infected with T. gondii.

Materials and Methods

Animals were studied in five groups: Control, Model, Model + CR20, 40, and 80 (with IP injection of 20, 40, and 80 mg/kg CR). T. gondii infection was prolonged for four weeks. The animals were then treated with CR or vehicle for two weeks and evaluated by behavioral tests at the end of the study. Hippocampal levels of oxidative stress biomarkers (superoxide dismutase; SOD, glutathione; GSH, and malondialdehyde; MDA) and gene expression and protein levels of hippocampal proinflammatory mediators (interleukin-1β; IL-1β, IL-6, IL-18, and tumor necrosis factor- α; TNF-α) were determined.

Results

Behavioral tests confirmed that long-term infection with T. gondii led to anxiety- and depressive-like behaviors. Antidepressant effects of CR were linked to modulation of oxidative stress and cytokine network in the hippocampal region of infected mice. These results showed that CR reduced anxiety and depression symptoms via regulation of oxidative stress and proinflammatory cytokines in the hippocampus of T. gondii-infected mice.

Conclusion

Therefore, CR can be used as a potential antidepressant agent against T. gondii-induced affective disorders.

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.

Effects of diverse Types of Toxoplasma gondii on the outcome of Alzheimer's disease in the rat model

Toxoplasma gondii has lifelong persistence in the brain and its cysts can affect gene expression and change diverse biological functions of neurons. Many studies indicated T. gondii infection as a risk factor for the development of behavioral changes and neurodegenerative diseases such as Alzheimer's disease (AD), although the etiopathogenetic link between them has not been exactly elucidated. The current study aimed to examine the effects of chronic toxoplasmosis infection with Types I, II, and III strains (RH, PRU, and VEG) alone and in combination on cognitive impairments and neuronal death in the Aβ1-42-induced rat model of Alzheimer's disease. In the chronic toxoplasmosis phase, Alzheimer's induction was conducted by injecting Aβ1-42 oligomers into the rat brain hippocampus. Behavioral tests were conducted 10 days after the AD induction. Real-time PCR was performed to evaluate T. gondii parasite burden by amplification of the B1 gene. Cytokines IL-1β, TNF-α, and IL-10 were assayed in brain tissue supernatant using ELISA. Also, histopathological examinations were conducted to calculate inflammatory changes and neuronal death in the brain. Our findings showed that chronic toxoplasmosis infection with PRU reduces cognitive disorders, while the RH strain of T. gondii plays a destructive role and aggravates cognitive impairments in AD. Also, infection with a combination of PRU and VEG strains significantly improved spatial learning and memory impairments in Alzheimer's rat model. Histopathological findings also confirmed the results of behavioral tests, so that in AβPRU and AβPRU + VEG groups, neuronal death and infiltration of inflammatory cells were negligible and significantly less than in Alzheimer's and AβRH groups. Our findings indicate that chronic toxoplasmosis infection with PRU strain alone, also in combination with VEG strain can significantly improve cognitive disorders in AD rats, while RH strain plays a destructive role in AD pathogenesis.

Study on the antagonistic effects of koumiss on Toxoplasma gondii infection in mice

Toxoplasma gondii is an important food-borne zoonotic parasite, and approximately one-third of people worldwide are positive for T. gondii antibodies. To date, there are no specific drugs or vaccines against T. gondii. Therefore, developing a new safe and effective method has become a new trend in treating toxoplasmosis. Koumiss is rich in probiotics and many components that can alleviate the clinical symptoms of many diseases via the functional characteristics of koumiss and its regulation of intestinal flora. To investigate the antagonistic effect of koumiss on T. gondii infection, the model of acute and chronic T. gondii infection was established in this study. The survival rate, SHIRPA score, serum cytokine levels, brain cyst counts, β-amyloid deposition and intestinal flora changes were measured after koumiss feeding. The results showed that the clinical symptoms of mice were improved at 6 dpi and that the SHIRPA score decreased after koumiss feeding (P < 0.05). At the same time, the levels of IL-4, IFN-γ and TNF-α decreased (P < 0.001, P < 0.001, P < 0.01). There was no significant difference of survival rate between koumiss treatment and the other groups. Surprisingly, the results of chronic infection models showed that koumiss could significantly reduce the number of brain cysts in mice (P < 0.05), improve β-amyloid deposition in the hippocampus (P < 0.01) and decrease the levels of IFN-γ and TNF-α (P < 0.01, P < 0.05). Moreover, koumiss could influence the gut microbiota function in resisting T. gondii infection. In conclusion, koumiss had a significant effect on chronic T. gondii infection in mice and could improve the relevant indicators of acute T. gondii infection in mice. The research provides new evidence for the development of safe and effective anti-T. gondii methods, as well as a theoretical basis and data support for the use of probiotics against T. gondii infection and broadened thoughts for the development and utilization of koumiss.

Back to the Future: The Role of Infections in Psychopathology. Focus on OCD

OBJECTIVE

Recently, there has been a resurgence of interest in the relationship between infections and psychopathology, given the increasing data on the neurotropism and neurological/psychiatric morbidity of the SARS-COV2 virus, responsible for the current worldwide pandemic. Although the majority of observations were those obtained in mood and schizophrenic disorders, a few data are also available on the presence of bacterial or viral infections in patients suffering from obsessive-compulsive disorder (OCD). Therefore, given the limited information, the present paper aimed at reviewing the most updated evidence of infections in neuropsychiatric disorders and their possible mechanisms of actions, with a narrow focus on microbes in OCD.

METHOD

This paper is a narrative review. The databases of PubMed, Scopus, Embase, PsycINFO and Google Scholar were accessed to research and collect English language papers published between 1 January 1980 and 31 December 2021. The data on PANDAS/PANS and those observed during severe brain infections were excluded.

RESULTS

Several pathogens have been associated with an increased risk to develop a broad spectrum of neuropsychiatric conditions, such as schizophrenia, mood disorders, autism, attention-deficit/hyperactivity disorder, anorexia nervosa, and post-traumatic stress disorder. Some evidence supported a possible role of infections also in the pathophysiology of OCD. Infections from Herpes simplex virus 1, Borna disease virus, Group A-Beta Hemolytic Streptococcus, Borrelia spp., and Toxoplasma gondii were actually found in patients with OCD. Although different mechanisms have been hypothesized, all would converge to trigger functional/structural alterations of specific circuits or immune processes, with cascade dysfunctions of several other systems.

CONCLUSIONS

Based on the current evidence, a possible contribution of different types of microbes has been proposed for different neuropsychiatric disorders including OCD. However, the currently available literature is meager and heterogeneous in terms of sample characteristics and methods used. Therefore, further studies are needed to better understand the impact of infectious agents in neuropsychiatric disorders. Our opinion is that deeper insights in this field might contribute to a better definition of biological underpinnings of specific clinical pictures, as well as to promote psychiatric precision medicine, with treatments based on altered pathological pathways of single patients. This might be particularly relevant in OCD, a disorder with a high proportion of patients who are resistant or do not respond to conventional therapeutic strategies.

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.

Persisting Microbiota and Neuronal Imbalance Following T. gondii Infection Reliant on the Infection Route

Toxoplasma gondii is a highly successful parasite capable of infecting all warm-blooded animals. The natural way of infection in intermediate hosts is the oral ingestion of parasite-contaminated water or food. In murine experimental models, oral infection (p.o.) of mice with T. gondii is applied to investigate mucosal and peripheral immune cell dynamics, whereas intraperitoneal infection (i.p.) is frequently used to study peripheral inflammation as well as immune cell – neuronal interaction in the central nervous system (CNS). However, the two infection routes have not yet been systematically compared along the course of infection. Here, C57BL/6 mice were infected p.o. or i.p. with a low dose of T. gondii cysts, and the acute and chronic stages of infection were compared. A more severe course of infection was detected following i.p. challenge, characterized by an increased weight loss and marked expression of proinflammatory cytokines particularly in the CNS during the chronic stage. The elevated proinflammatory cytokine expression in the ileum was more prominent after p.o. challenge that continued following the acute phase in both i.p. or p.o. infected mice. This resulted in sustained microbial dysbiosis, especially after p.o. challenge, highlighted by increased abundance of pathobionts from the phyla proteobacteria and a reduction of beneficial commensal species. Further, we revealed that in the CNS of i.p. infected mice CD4 and CD8 T cells displayed higher IFNγ production in the chronic stage. This corresponded with an increased expression of C1q and CD68 in the CNS and reduced expression of genes involved in neuronal signal transmission. Neuroinflammation-associated synaptic alterations, especially PSD-95, VGLUT, and EAAT2 expression, were more pronounced in the cortex upon i.p. infection highlighting the profound interplay between peripheral inflammation and CNS homeostasis.

Le Petit Machiavellian Prince: Effects of Latent Toxoplasmosis on Political Beliefs and Values

Humans infected by Toxoplasma gondii express no specific symptoms but manifest higher incidence of many diseases, disorders and differences in personality and behavior. The aim of this study was to compare the political beliefs and values of Toxoplasma-infected and Toxoplasma-free participants. We measured beliefs and values of 2315 responders via an online survey (477 Toxoplasma-infected) using the Political Beliefs and Values Inventory (PI34). This study showed Toxoplasma-infected and Toxoplasma-free participants of our cross-sectional study differed in three of four factors of PI34, scoring higher in Tribalism and lower in Cultural liberalism and Anti-Authoritarianism. We found sex differences in political beliefs associated with Toxoplasma infection. Infected women scored higher in tribalism and lower in cultural liberalism, compared with the Toxoplasma-free control group, while infected men scored higher in economic equity. These results fit with sexual differences in behavior and attitude observed after toxoplasmosis infection. Controlling for the effect of worse physical health and mental health had little impact, suggesting that impaired health did not cause these changes. Rather than adaptation to prevalence of parasites, as suggested by parasite-stress theory, the differences might be side-effects of long-term mild inflammatory reaction. However, to get clear picture of the mild inflammation effects, more research focused on different infectious diseases is needed.

The Role of Intestinal Microbial Metabolites in the Immunity of Equine Animals Infected With Horse Botflies

The microbiota and its metabolites play an important role in regulating the host metabolism and immunity. However, the underlying mechanism is still not well studied. Thus, we conducted the LC-MS/MS analysis and RNA-seq analysis on Equus przewalskii with and without horse botfly infestation to determine the metabolites produced by intestinal microbiota in feces and differentially expressed genes (DEGs) related to the immune response in blood and attempted to link them together. The results showed that parasite infection could change the composition of microbial metabolites. These identified metabolites could be divided into six categories, including compounds with biological roles, bioactive peptides, endocrine-disrupting compounds, pesticides, phytochemical compounds, and lipids. The three pathways involving most metabolites were lipid metabolism, amino acid metabolism, and biosynthesis of other secondary metabolites. The significant differences between the host with and without parasites were shown in 31 metabolites with known functions, which were related to physiological activities of the host. For the gene analysis, we found that parasite infection could alarm the host immune response. The gene of “cathepsin W” involved in innate and adaptive immune responses was upregulated. The two genes of the following functions were downregulated: “protein S100-A8” and “protein S100-A9-like isoform X2” involved in chemokine and cytokine production, the toll-like receptor signaling pathway, and immune and inflammatory responses. GO and KEGG analyses showed that immune-related functions of defense response and Th17 cell differentiation had significant differences between the host with and without parasites, respectively. Last, the relationship between metabolites and genes was determined in this study. The purine metabolism and pyrimidine metabolism contained the most altered metabolites and DEGs, which mainly influenced the conversion of ATP, ADP, AMP, GTP, GMP, GDP, UTP, UDP, UMP, dTTP, dTDP, dTMP, and RNA. Thus, it could be concluded that parasitic infection can change the intestinal microbial metabolic activity and enhance immune response of the host through the pathway of purine and pyrimidine metabolism. This results will be a valuable contribution to understanding the bidirectional association of the parasite, intestinal microbiota, and host.

Impact of Plant-Based Foods and Nutraceuticals on Toxoplasma gondii Cysts: Nutritional Therapy as a Viable Approach for Managing Chronic Brain Toxoplasmosis

Toxoplasma gondii is an obligate intracellular parasite that mainly infects warm-blooded animals including humans. T. gondii can encyst and persist chronically in the brain, leading to a broad spectrum of neurological sequelae. Despite the associated health threats, no clinical drug is currently available to eliminate T. gondii cysts. In a continuous effort to uncover novel therapeutic agents for these cysts, the potential of nutritional products has been explored. Herein, we describe findings from in vitro and in vivo studies that support the efficacy of plant-based foods and nutraceuticals against brain cyst burden and cerebral pathologies associated with chronic toxoplasmosis. Finally, we discuss strategies to increase the translatability of preclinical studies and nutritional products to address whether nutritional therapy can be beneficial for coping with chronic T. gondii infections in humans.

Effects of Toxoplasma gondii on Levels of Interleukin-5 in Parkinson's Patients

Parkinson's disease (PD) is a psychiatric neurological infection of the focal sensory system and is accepted as a multifactorial disease. Chronic Toxoplasmosis is sometimes associated with the proliferation of bradyzoites in the nervous system. The measurement of interleukin-5 (IL-5) as an inflammatory mediator in patients with PD and Toxoplasmosis infection may be helpful in determining the correlation between these diseases. In the present study, 80 examples were collected, including 35 patients diagnosed with idiopathic PD and 45 samples from healthy people from Najaf, Babylon, and Baghdad provinces, Iraq. After measuring the immunoglobulin G (IgG) antibody of Toxoplasma gondii, the level of IL-5 was evaluated in different groups. Serological examination showed that the IgG antibody of Toxoplasmosis increased (P<0.05) in people with PD (65.71%). Serum levels of IL-5 significantly decreased in people with PD. It is noteworthy that comparing serum levels of IL-5 between two groups of people with and without chronic Toxoplasmosis revealed that there was a significant decrease (P<0.05) in a concentration of serum IL-5 in individuals with chronic Toxoplasmosis. The current study confirmed the conceivable association between T. gondii and PD, and further research is recommended to explain the association between PD and Toxoplasmosis.

Toxoplasmosis: Targeting neurotransmitter systems in psychiatric disorders

The most common form of the disease caused by Toxoplasma gondii (T. gondii) is latent toxoplasmosis due to the formation of tissue cysts in various organs, such as the brain. Latent toxoplasmosis is probably a risk factor in the development of some neuropsychiatric disorders. Behavioral changes after infection are caused by the host immune response, manipulation by the parasite, central nervous system (CNS) inflammation, as well as changes in hormonal and neuromodulator relationships. The present review focused on the exact mechanisms of T. gondii effect on the alteration of behavior and neurotransmitter levels, their catabolites and metabolites, as well as the interaction between immune responses and this parasite in the etiopathogenesis of psychiatric disorders. The dysfunction of neurotransmitters in the neural transmission is associated with several neuropsychiatric disorders. However, further intensive studies are required to determine the effect of this parasite on altering the level of neurotransmitters and the role of neurotransmitters in the etiology of host behavioral changes.

Coalition of Biological Agent (Melatonin) With Chemotherapeutic Agent (Amphotericin B) for Combating Visceral Leishmaniasis via Oral Administration of Modified Solid Lipid Nanoparticles

In this study, 2-hydroxypropyl-β-cyclodextrin (HPβCD) grafted solid lipid nanoparticle (SLN)-based bioconjugate was synthesized and used for administering a combination of melatonin (Mel) and amphotericin B (AmB) orally for effective visceral leishmaniasis (VL) treatment. The formulations (HPCD-Mel-AmB SLN) were synthesized by the emulsion solvent evaporation method. HPCD-Mel-AmB SLN showed a high loading capacity and a high entrapment efficiency of AmB (% DL = 9.0 ± 0.55 and % EE = 87.9 ± 0.57) and Mel (% DL = 7.5 ± 0.51 and % EE = 63 ± 6.24). The cumulative percent release of AmB and Mel was 66.10 and 73.06%, respectively, up to 72 h. Time-dependent cellular uptake was noticed for HPCD-Mel-AmB SLN for 4 h. Further, HPCD-Mel-AmB SLN did not show any toxic effects on J774A.1 macrophages and Swiss albino mice. HPCD-Mel-AmB SLN (10 mg/kg ×5 days, p.o.) has significantly diminished (98.89%) the intracellular parasite load in liver tissues of L. donovani-infected BALB/c mice, subsequently highlighting the role of melatonin toward an effective strategy in combating leishmanial infection. Therefore, these results indicated that administration of HPCD-Mel-AmB SLN improve the therapeutic index of the first-line drug in addition to the introduction of biological agent and would be a promising therapeutic candidate for effective VL therapy. In the present study, the objective is to test the efficacy of the chemotherapeutic approach in combination with a biological immunomodulatory agent against leishmanial infection using in vitro and in vivo studies. This information suggests that melatonin could be an efficacious and potent antileishmanial agent.

Coxsackievirus B4 Transplacental Infection Severely Disturbs Central Tolerogenic Mechanisms in the Fetal Thymus

Thymus plays a fundamental role in central tolerance establishment, especially during fetal life, through the generation of self-tolerant T cells. This process consists in T cells education by presenting them tissue-restricted autoantigens promiscuously expressed by thymic epithelial cells (TECs), thus preventing autoimmunity. Thymus infection by Coxsackievirus B (CV-B) during fetal life is supposed to disturb thymic functions and, hence, to be an inducing or accelerating factor in the genesis of autoimmunity. To further investigate this hypothesis, in our current study, we analyzed thymic expression of autoantigens, at the transcriptional and protein level, following in utero infection by CV-B4. mRNA expression levels of Igf2 and Myo7, major autoantigens of pancreas and heart, respectively, were analyzed in whole thymus and in enriched TECs together along with both transcription factors, Aire and Fezf2, involved in autoantigens expression in the thymus. Results show that in utero infection by CV-B4 induces a significant decrease in Igf2 and Myo7 expression at both mRNA and protein level in whole thymus and in enriched TECs as well. Moreover, a correlation between viral load and autoantigens expression can be observed in the whole thymus, indicating a direct effect of in utero infection by CV-B4 on autoantigens expression. Together, these results indicate that an in utero infection of the thymus by CV-B4 may interfere with self-tolerance establishment in TECs by decreasing autoantigen expression at both mRNA and protein level and thereby increase the risk of autoimmunity onset.

Latent Toxoplasma gondii infections are associated with elevated biomarkers of inflammation and vascular injury

BACKGROUND

Toxoplasma gondii is a protozoan parasite that infects cats as definitive hosts and other warm-blooded animals including humans as intermediate hosts. It forms infectious cysts in the brain, muscle and other tissues establishing life-long latent infection. Approximately 10% of the US population is infected. While latent infections are largely asymptomatic, they are associated with neurological deficits and elevated risks of neuropsychiatric diseases.

METHODS

This cross-sectional epidemiological study investigated associations of T. gondii infections with biomarkers of inflammation and vascular injury: soluble intercellular adhesion molecule 1 (ICAM-1), soluble vascular cell adhesion molecule 1 (VCAM-1), C-reactive protein (CRP), and serum amyloid A (SAA). Serum samples from 694 adults in the Raleigh-Durham-Chapel Hill, North Carolina metropolitan area were tested for IgG antibody response to T. gondii, and for the above biomarkers using commercially available assays.

RESULTS

T. gondii seroprevalence rate in this sample was 9.7%. Seropositivity was significantly associated with 11% (95% confidence limits 4, 20%) greater median levels of VCAM-1 (p = 0.003), and marginally significantly with 9% (1, 17%), and 36% (1, 83%) greater median levels of ICAM-1, and CRP, respectively (p = 0.04 for each) after adjusting for sociodemographic and behavioral covariates, while the 23% (- 7, 64%) adjusted effect on SAA was not statistically significant (p = 0.15).

CONCLUSIONS

Latent infections with T. gondii are associated with elevated biomarkers of chronic inflammation and vascular injury that are also known to be affected by ambient air pollution.

Toxoplasmosis: stages of the protozoan life cycle and risk assessment in humans and animals for an enhanced awareness and an improved socio-economic status

Toxoplasma gondii is a protozoan parasite distributed globally. It causes toxoplasmosis, which is prevalent in animals, birds, and soil. T. gondii infection leads to severe pathological impacts in immunodeficient patients and congenital cases. This review indicated that high prevalence groups had close contact with cats, dogs, consumed uncooked raw fruits, meat, or vegetables and the socio-economic level noted to be one of the crucial factors that influence toxoplasmosis. Toxoplasmosis infection is high in low-income countries and low in developed European countries. Immunosuppressed groups and pregnant women were the highly vulnerable groups. The epidemiology of the parasite enumerated various routes of infections; but consumption of T. gondii contaminated food was the major route of disease transmission. However, the role of meat and meat-producing animals on disease transmission remained unclear. Unfiltered water acts as the primary reservoir of toxoplasmosis transmission. The diagnostic methods for determining T. gondii infection are not the gold standard, and different approaches have been prescribed to analyze the infected populations based on the organs affected. Although toxoplasmosis was reported before 70 years, no appropriate solution noted to be recommended to treat this disease. Based on the present analyses, it concluded that the eradication of toxoplasmosis would be challenging from the world until people's socio-economic level is improved. The main aim of the present study was to analyze and update the disease transmission, epidemiology, and possible clinical interventions of toxoplasmosis.

Influence of the Host and Parasite Strain on the Immune Response During Toxoplasma Infection

Toxoplasma gondii is an exceptionally successful parasite that infects a very broad host range, including humans, across the globe. The outcome of infection differs remarkably between hosts, ranging from acute death to sterile infection. These differential disease patterns are strongly influenced by both host- and parasite-specific genetic factors. In this review, we discuss how the clinical outcome of toxoplasmosis varies between hosts and the role of different immune genes and parasite virulence factors, with a special emphasis on Toxoplasma-induced ileitis and encephalitis.

Age-related changes in cerebral congenital toxoplasmosis: Histopathological and immunohistochemical evaluation

Congenital toxoplasmosis is a widespread worldwide disease producing varying degrees of damage to the fetus including ocular and neurological impairment. However, the underlying mechanisms are not yet clear. Therefore, the current study aimed to investigate the progress of congenital cerebral toxoplasmosis in experimentally infected offspring animal model at different age groups till become adults. To fulfill this aim, the offspring of Me49 T. gondii infected pregnant mice were divided into groups; embryo, infant, young and adult phases. Blood and brain samples were collected for further hormonal and histopathological studies and immunohistochemical staining of glial fibrillary acidic protein (GFAP) and synaptophysin (SYN). Our results showed several encephalitic changes in the infected groups ranging from gliosis to reduced cortical cell number and fibrinoid degeneration of the brain. We showed increased expression of GFAP and SYN indicating activation of astrocytes and modification of the synaptic function, respectively. These changes started intrauterine following congenital infection and increased progressively afterward. Moreover, infected mice had elevated corticosterone levels. In conclusion, the current study provided new evidences for the cellular changes especially in the infected embryo and highlighted the role of GFAP and SYN that may be used as indicators for T. gondii-related neuropathy.

Association between schizophrenia and Toxoplasma gondii infection in Algeria

Toxoplasmosis has been previously associated with an increased risk of having schizophrenia in several epidemiological studies. The aim of this prospective study was to examine for the first time a possible association between positive serology to Toxoplasma gondii (T. gondii) and schizophrenia in the Algerian population. Seventy patients affected by schizophrenia according to DSM-5 criteria and seventy healthy controls were enrolled in the study. We found a significant association between schizophrenia and the infection status with a seroprevalence of 70% in patients with schizophrenia compared to 52.9% in controls and a calculated odds ratio of 2.081. In addition, while T. gondii seroprevalence increases significantly with age in controls, this association was not observed in patients with schizophrenia, which display a high percentage of seropositive subjects under 38 years of age, suggesting that T. gondii infection may promote the onset of schizophrenia. Moreover, our analysis also revealed that patients with schizophrenia had significantly lower levels of serum immunoglobulins G (IgG) to T. gondii compared to controls. Thus, this study adds to previous research questioning the asymptomatic aspect of chronic toxoplasmosis and the etiology of schizophrenia.

From conifers to cognition: Microbes, brain and behavior

A diversity of bacteria, protozoans and viruses ("endozoites") were recently uncovered within healthy tissues including the human brain. By contrast, it was already recognized a century ago that healthy plants tissues contain abundant endogenous microbes ("endophytes"). Taking endophytes as an informative precedent, we overview the nature, prevalence, and role of endozoites in mammalian tissues, centrally focusing on the brain, concluding that endozoites are ubiquitous in diverse tissues. These passengers often remain subclinical, but they are not silent. We address their routes of entry, mechanisms of persistence, tissue specificity, and potential to cause long-term behavioral changes and/or immunosuppression in mammals, where rabies virus is the exemplar. We extend the discussion to Herpesviridae, Coronaviridae, and Toxoplasma, as well as to diverse bacteria and yeasts, and debate the advantages and disadvantages that endozoite infection might afford to the host and to the ecosystem. We provide a clinical perspective in which endozoites are implicated in neurodegenerative disease, anxiety/depression, and schizophrenia. We conclude that endozoites are instrumental in the delicate balance between health and disease, including age-related brain disease, and that endozoites have played an important role in the evolution of brain function and human behavior.

Majid R. A Review on the Prevalence of Toxoplasma gondii in Humans and Animals Reported in Malaysia from 2008-2018

Toxoplasmosis is a disease caused by the protozoan parasite Toxoplasma gondii (T. gondii). Human toxoplasmosis seroprevalence in Malaysia has increased since it was first reported in 1973 as shown in previous reviews of 1991 and 2007. However, over a decade since the last review, comprehensive data on toxoplasmosis in Malaysia is lacking. This work aimed at reviewing articles on toxoplasmosis research in Malaysia in order to identify the research gaps, create public awareness, and efforts made so far and proffer management options on the disease. The present review examines the available published research articles from 2008 to 2018 related to toxoplasmosis research conducted in Malaysia. The articles reviewed were retrieved from nine credible databases such as Web of Science, Google Scholar, ScienceDirect, PubMed, Scopus, Springer, Wiley online library, Ovid, and Cochrane using the keywords; Malaysia, toxoplasmosis, Toxoplasma gondii, toxoplasma encephalitis, seroprevalence, human immunodeficiency virus (HIV) patients, pregnant women, genotype strain, anti-toxoplasma antibodies, felines, and vaccine. The data highlighted seropositive cases from healthy community members in Pangkor Island (59.7%) and among migrant workers (57.4%) at alarming rates, as well as 42.5% in pregnant women. Data on animal seroprevalence were limited and there was no information on cats as the definitive host. Genetic characterization of Toxoplasma gondii from HIV patients; pregnant women, and domestic cats is lacking. This present review on toxoplasmosis is beneficial to researchers, health workers, animal health professionals, and policymakers. Therefore, attention is required to educate and enlighten health workers and the general public about the risk factors associated with T. gondii infection in Malaysia.

Toxoplasma gondii infection and multiple sclerosis: An age- and a gender-matched case-control seroprevalence study

The link between Toxoplasma gondii infection and multiple sclerosis remains controversial. In the present study, we aimed to determine the association between T.gondii seropositivity and multiple sclerosis. Using an age- and gender-matched case-control study, we studied 45 patients who had multiple sclerosis attended in two public hospitals and 225 control subjects without this disease and other neurological disorders in Durango City, Mexico. Serum samples of cases and controls were analyzed for detection of anti-Toxoplasma IgG using a commercially available enzyme-linked immunoassay. One (2.22%) of the 45 patients with multiple sclerosis, and 15 (6.67%) of the 225 control subjects without this disease were seropositive for anti-T. gondii IgG antibodies. No statistically significant difference (OR = 0.31; 95% CI: 0.04–2.47; P = 0.48) in seroprevalence of anti-T. gondii IgG antibodies between cases and controls was found. The frequency of T. gondii seropositivity did not vary among cases and controls about sex or age groups. Results of this study do not support an association between seropositivity to T. gondii and multiple sclerosis. However, additional research with larger sample sizes to confirm this lack of association should be conducted.

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

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

The Bradyzoite: A Key Developmental Stage for the Persistence and Pathogenesis of Toxoplasmosis

Toxoplasma gondii is a ubiquitous parasitic protist found in a wide variety of hosts, including a large proportion of the human population. Beyond an acute phase which is generally self-limited in immunocompetent individuals, the ability of the parasite to persist as a dormant stage, called bradyzoite, is an important aspect of toxoplasmosis. Not only is this stage not eliminated by current treatments, but it can also reactivate in immunocompromised hosts, leading to a potentially fatal outcome. Yet, despite its critical role in the pathology, the bradyzoite stage is relatively understudied. One main explanation is that it is a considerably challenging model, which essentially has to be derived from in vivo sources. However, recent progress on genetic manipulation and in vitro differentiation models now offers interesting perspectives for tackling key biological questions related to this particularly important developmental stage.

Latent Toxoplasmosis Effects on Rodents and Humans: How Much is Real and How Much is Media Hype?

Toxoplasma gondii is a ubiquitous, intracellular protozoan parasite with a broad range of intermediate hosts, including humans and rodents. In many hosts, T. gondii establishes a latent long-term infection by converting from its rapidly dividing or lytic form to its slowly replicating and encysting form. In humans and rodents, the major organ for encystment is the central nervous system (CNS), which has led many to investigate how this persistent CNS infection might influence rodent and human behavior and, more recently, neurodegenerative diseases.

Toxoplasma gondii is a ubiquitous, intracellular protozoan parasite with a broad range of intermediate hosts, including humans and rodents. In many hosts, T. gondii establishes a latent long-term infection by converting from its rapidly dividing or lytic form to its slowly replicating and encysting form. In humans and rodents, the major organ for encystment is the central nervous system (CNS), which has led many to investigate how this persistent CNS infection might influence rodent and human behavior and, more recently, neurodegenerative diseases. Given the interest in this topic, here we seek to take a global approach to the data for and against the effects of latent T. gondii on behavior and neurodegeneration and the proposed mechanisms that might underlie behavior modifications.

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.

Exposure to common infections and risk of suicide and self-harm: a longitudinal general population study

Common infectious agents, such as Toxoplasma gondii (T. gondii) and several human herpes viruses, have been linked to increased risk of self-harm. The aim of this study was to investigate the associations between self-harm and seropositivity to T. gondii, Epstein-Barr virus (EBV), Herpes Simplex virus Type 1 (HSV-1), and Cytomegalovirus (CMV). IgM and IgG antibodies to these infections were measured in the Health 2000 project nationally representative of the whole Finnish adult population, and 6250 participants, age 30 and over, were followed for 15 years via registers. In addition, lifetime suicidal ideation and suicide attempts based on medical records and interview were assessed within a subsample of 694 participants screened to a substudy for possible psychotic symptoms or as controls. Among the 6250 participants, 14 individuals died of suicide and an additional 4 individuals had a diagnosis of intentional self-harm during follow-up. Serological evidence of lifetime or acute infections was not found to be associated with these suicidal outcomes. However, in the subsample, those seropositive for CMV had fewer suicide attempts compared to those seronegative, adjusting for gender, age, educational level, childhood family size, regional residence, CRP, and screen status (OR for multiple attempts = 0.40, 95% confidence interval 0.20‒0.83, p = 0.014). To conclude, common infections were not associated with risk of death by suicide or with self-harm diagnoses at a 15-year follow-up in the general population sample. Our finding of an increased number of suicide attempts among persons seronegative for CMV calls for further research.

Tick transmission of toxoplasmosis

Introduction: Infection with Toxoplasma gondii (T. gondii) causes the disease toxoplasmosis in humans and animals. Oral transmission alone may not explain the widespread distribution of this parasite over large species of host animals and geographic areas.Areas covered: Limited studies indicate the potential role of ticks in the distribution of T. gondii. The possibility of transmission of T. gondii has been demonstrated in Dermacentor variabilis, Dermacentor andersoni, Amblyomma americanum, Dermacentor reticulatus, Ixodes ricinus, Ixodes amblyomma, Amblyomma cajennense, Ornithodorus moubata and Haemaphysalis longicornis. Tick transmission of T. gondii, spread of ticks and pathogens by migratory birds and presence in the United States (US) of tick vectors of human and animal disease like Haemaphysalis longicornis indigenous to other parts of the world provide a possible mechanism for the widespread distribution of T. gondii, and a potentially expanding disease threat.Expert opinion: The evidence indicates that T. gondii is potentially an unrecognized tick-borne pathogen spreading toxoplasmosis, and that clinicians might consider toxoplasmosis in the differential diagnosis of tickborne diseases.

Toxoplasmosis and mental disorders in the Russian Federation (with special reference to schizophrenia)

The association of latent toxoplasmosis with mental disorders in general and with schizophrenia in particular was noticed in the mid-1950s. In subsequent years, the role of Toxoplasma gondii was established based on its ability to survive for long periods of time in the nerve cells of the brain. The acute manifestations of the infection include psychopathic symptoms resembling those of schizophrenia. In the former USSR, and in other parts of the world, a number of studies were performed with respect to the association of latent toxoplasmosis and schizophrenia. However, with the dissolution of the USSR at the beginning of the 1990s, studies on the subject were halted due to financial problems and have resumed only recently. The reasons for the resumption of such studies in contemporary Russia are related to the progressively increasing incidence of schizophrenia over the last 25-30 years in the country. According to official data, approximately 550 000 persons reported suffering from the disease in 2014. There are reasons to believe that this is only a fraction of the real burden of the disease. Economically, it cost the state no less than approximately US $10 billion. The purpose of the study was to identify the level of toxoplasmosis seroprevalence in patients with verified diagnoses of schizophrenia in comparison to healthy people in Moscow City and in the Moscow region. A total of 155 persons constituted the patients group and 152 healthy people were in the control group. An integrated approach to the diagnosis and comparison of data from the entire spectrum of serological markers of infection was used, including the detection of specific IgM and the determination of IgG concentrations. It was found that among persons with neuropsychiatric disorders, the incidence of cases with latent toxoplasmosis was higher than in the control group. The effect of toxoplasmosis was significant and similar for men and women. Further statistical analyses revealed that among patients with a diagnosis of schizophrenia, the incidence of latent toxoplasmosis was significantly higher than in the control group. These data are in agreement with the results of similar studies in other countries.

Monitoring of kynurenine pathway metabolites, neurotransmitters and their metabolites in blood plasma and brain tissue of individuals with latent toxoplasmosis

The aim of the presented work was to develop a highly sensitive, accurate and rapid analytical method for the determination of concentration levels of tryptophan and its metabolites of kynurenine catabolic pathway, as well as neurotransmitters and their metabolites in complex biological matrices (brain tissue and blood plasma). The developed analytical method consists of analytes separation from the biological matrices by protein precipitation (blood plasma) or solvent extraction (brain tissue), derivatization of the analytes and their detection by high-performance liquid chromatography combined with mass spectrometry. Individual steps of the whole process were optimized and the method was validated in the terms of selectivity, linearity (R²≥0.980), precision (RSD ≤ 13.3%), recovery (≥82.0%), limit of detection (1.8 ng/mL of blood plasma, 2.2 pg/mg of brain tissue) and limit of quantification (2.5 ng/mL of blood plasma, 2.8 pg/mg of brain tissue). The method was subsequently verified by an animal study, where the concentration levels of the analytes in biological matrices (blood plasma and brain tissue) of T. gondii - infected rats and control animals were compared. All the data obtained from the animal study were statistically evaluated. Increased concentration levels of kynurenine catabolic pathway metabolites (e.g. kynurenine, 3-hydroxykynurenine, quinolinic acid) were observed in the case of T. gondii - infected rats in contrast to the control group. The opposite effect was determined in the case of serotonin and its metabolite 5-hydroxyindoleacetic acid, where higher concentration levels were found in blood plasma of healthy subjects. Finally, Principal Component Analysis (PCA) was utilized for a score plot formation. PCA score plots have demonstrated the similarities of individuals within each group and the differences among the groups.

Maternal and Congenital Toxoplasmosis: Diagnosis and Treatment Recommendations of a French Multidisciplinary Working Group

Women infected with toxoplasmosis during pregnancy do not present symptoms in most cases, but the consequences of the congenital infection may be severe for the unborn child. Fetal damage can range from asymptomatic to severe neurological alterations to retinal lesions prone to potential flare up and relapses lifelong. Despite the possible severity of outcome, congenital toxoplasmosis (CT) is a neglected disease. There is no consensus regarding screening during pregnancy, prenatal/postnatal treatment or short or medium term follow-up. Since 1992, France has offered systematic serological testing to non-immune pregnant women, monthly until delivery. Any maternal infection is thus detected; moreover, diagnosis of congenital infection can be made at birth and follow-up can be provided. “Guidelines” drawn up by a multidisciplinary group are presented here, concerning treatment, before and after birth. The recommendations are based on the regular analysis of the literature and the results of the working group. The evaluation of the recommendations takes into account the robustness of the recommendation and the quality of the evidence.

Advances and Challenges in Understanding Cerebral Toxoplasmosis

Toxoplasma gondii is a widespread parasitic pathogen that infects over one third of the global human population. The parasite invades and chronically persists in the central nervous system (CNS) of the infected host. Parasite spread and persistence is intimately linked to an ensuing immune response, which does not only limit parasite-induced damage but also may facilitate dissemination and induce parasite-associated immunopathology. Here, we discuss various aspects of toxoplasmosis where knowledge is scarce or controversial and, the recent advances in the understanding of the delicate interplay of T. gondii with the immune system in experimental and clinical settings. This includes mechanisms for parasite passage from the circulation into the brain parenchyma across the blood-brain barrier during primary acute infection. Later, as chronic latent infection sets in with control of the parasite in the brain parenchyma, the roles of the inflammatory response and of immune cell responses in this phase of the disease are discussed. Additionally, the function of brain resident cell populations is delineated, i.e., how neurons, astrocytes and microglia serve both as target cells for the parasite but also actively contribute to the immune response. As the infection can reactivate in the CNS of immune-compromised individuals, we bring up the immunopathogenesis of reactivated toxoplasmosis, including the special case of congenital CNS manifestations. The relevance, advantages and limitations of rodent infection models for the understanding of human cerebral toxoplasmosis are discussed. Finally, this review pinpoints questions that may represent challenges to experimental and clinical science with respect to improved diagnostics, pharmacological treatments and immunotherapies.

Modelling Toxoplasma gondii infection in a 3D cell culture system In Vitro: Comparison with infection in 2D cell monolayers

Three-dimensional (3D) cell culture models bridge the gap between two-dimensional (2D) monolayer cultures and animal models. Physiologically relevant, 3D culture models have significantly advanced basic cell science and provide unique insights into host-pathogen interactions intrinsically linked to cell morphology. Toxoplasma gondii is an obligate intravacuolar parasite that chronically infects a large portion of the global human population. Our current understanding of Toxoplasma infection is largely based on 2D cell cultures, in which mammalian cells are grown on flat surfaces. However, 2D cell cultures may not recapitulate key conditions of in vivo infections as they introduce artificial pressures and tensions, which may subsequently alter infectious processes that are dependent on spatiality, e.g., invasion, replication and egress. In this study, we adapted a collagen-based 3D cell culture system to reproduce the 3D environment of T. gondii natural infections for investigation of the replication and egress of the parasite from the parasitophorous vacuole. Suspended in the 3D matrix, Toxoplasma-infected VERO cells have round morphology, as opposed to infected VERO cells in 2D monolayers. The doubling time of Toxoplasma in VERO cells within the matrix is comparable to that of parasites cultivated in VERO cell monolayers. In the absence of the pressure of flattened host cells grown in 2D cultures, the parasitophorous vacuole of T. gondii has a globular shape, with intravacuolar parasites distributed radially, forming 3D spherical ‘rosette’ structures. Parasites egress radially away from the ruptured host cell in 3D matrices, in contrast to Toxoplasma cultivated in 2D monolayer cultures, where the parasites escape perpendicularly from the flat surface below the host cells. These observations demonstrate the utility of collagen matrices for studying parasite modes of infection as these 3D assays more closely mimic in vivo conditions.

Toxoplasmosis: A pathway to neuropsychiatric disorders

Toxoplasma gondii is an obligate intracellular parasite that resides, in a latent form, in the human central nervous system. Infection with Toxoplasma drastically alters the behaviour of rodents and is associated with the incidence of specific neuropsychiatric conditions in humans. But the question remains: how does this pervasive human pathogen alter behaviour of the mammalian host? This fundamental question is receiving increasing attention as it has far reaching public health implications for a parasite that is very common in human populations. Our current understanding centres on neuronal changes that are elicited directly by this intracellular parasite versus indirect changes that occur due to activation of the immune system within the CNS, or a combination of both. In this review, we explore the interactions between Toxoplasma and its host, the proposed mechanisms and consequences on neuronal function and mental health, and discuss Toxoplasma infection as a public health issue.

Treatment of Toxoplasmosis: Historical Perspective, Animal Models, and Current Clinical Practice

Primary Toxoplasma gondii infection is usually subclinical, but cervical lymphadenopathy or ocular disease can be present in some patients. Active infection is characterized by tachyzoites, while tissue cysts characterize latent disease. Infection in the fetus and in immunocompromised patients can cause devastating disease. The combination of pyrimethamine and sulfadiazine (pyr-sulf), targeting the active stage of the infection, is the current gold standard for treating toxoplasmosis, but failure rates remain significant. Although other regimens are available, including pyrimethamine in combination with clindamycin, atovaquone, clarithromycin, or azithromycin or monotherapy with trimethoprim-sulfamethoxazole (TMP-SMX) or atovaquone, none have been found to be superior to pyr-sulf, and no regimen is active against the latent stage of the infection. Furthermore, the efficacy of these regimens against ocular disease remains uncertain. In multiple studies, systematic screening for Toxoplasma infection during gestation, followed by treatment with spiramycin for acute maternal infections and with pyr-sulf for those with established fetal infection, has been shown to be effective at preventing vertical transmission and minimizing the severity of congenital toxoplasmosis (CT). Despite significant progress in treating human disease, there is a strong impetus to develop novel therapeutics for both the acute and latent forms of the infection. Here we present an overview of toxoplasmosis treatment in humans and in animal models. Additional research is needed to identify novel drugs by use of innovative high-throughput screening technologies and to improve experimental models to reflect human disease. Such advances will pave the way for lead candidates to be tested in thoroughly designed clinical trials in defined patient populations.

Environmental risk factors for Toxoplasma gondii infections and the impact of latent infections on allostatic load in residents of Central North Carolina

BACKGROUND

Toxoplasma gondii infection can be acquired through ingestion of infectious tissue cysts in undercooked meat or environmental oocysts excreted by cats. This cross-sectional study assessed environmental risk factors for T. gondii infections and an association between latent infections and a measure of physiologic dysregulation known as allostatic load.

METHODS

Serum samples from 206 adults in the Durham-Chapel Hill, North Carolina area were tested for immunoglobulin (IgG) responses to T. gondii using commercial ELISA kits. Allostatic load was estimated as a sum of 15 serum biomarkers of metabolic, neuroendocrine and immune functions dichotomized at distribution-based cutoffs. Vegetated land cover within 500 m of residences was estimated using 1 m resolution data from US EPA's EnviroAtlas.

RESULTS

Handling soil with bare hands at least weekly and currently owning a cat were associated with 5.3 (95% confidence limits 1.4; 20.7) and 10.0 (2.0; 50.6) adjusted odds ratios (aOR) of T. gondii seropositivity, respectively. There was also a significant positive interaction effect of handling soil and owning cats on seropositivity. An interquartile range increase in weighted mean vegetated land cover within 500 m of residence was associated with 3.7 (1.5; 9.1) aOR of T. gondii seropositivity. Greater age and consumption of undercooked pork were other significant predictors of seropositivity. In turn, T. gondii seropositivity was associated with 61% (13%; 130%) greater adjusted mean allostatic load compared to seronegative individuals. In contrast, greater vegetated land cover around residence was associated with significantly reduced allostatic load in both seronegative (p < 0.0001) and seropositive (p = 0.004) individuals.

CONCLUSIONS

Residents of greener areas may be at a higher risk of acquiring T. gondii infections through inadvertent ingestion of soil contaminated with cat feces. T. gondii infections may partially offset health benefits of exposure to the natural living environment.

Toxoplasma gondii: Biological Parameters of the Connection to Schizophrenia

It is increasingly evident that the brain is not truly an immune privileged site and that cells of the central nervous system are sensitive to the inflammation generated when the brain is fighting off infection. Among the many microorganisms that have access to the brain, the apicomplexan protozoan Toxoplasma gondii has been one of the most studied. This parasite has been associated with many neuropsychiatric disorders including schizophrenia. This article provides a comprehensive review of the status of Toxoplasma research in schizophrenia. Areas of interest include (1) the limitations and improvements of immune-based assays to detect these infections in humans, (2) recent discoveries concerning the schizophrenia-Toxoplasma association, (3) findings of Toxoplasma neuropathology in animal models related to schizophrenia pathogenesis, (4) interactions of Toxoplasma with the host genome, (5) gastrointestinal effects of Toxoplasma infections, and (6) therapeutic intervention of Toxoplasma infections.

Identification and characterization of Taenia solium enolase as a plasminogen-binding protein

The larval stage of Taenia solium (cysticerci) is the causal agent of human and swine cysticercosis. When ingested by the host, T. solium eggs are activated and hatch in the intestine, releasing oncospheres that migrate to various tissues and evolve into cysticerci. Plasminogen (Plg) receptor proteins have been reported to play a role in migration processes for several pathogens. This work is aimed to identify Plg-binding proteins in T. solium cysticerci and determine whether T. solium recombinant enolase (rTsEnoA) is capable of specifically binding and activating human Plg. To identify Plg-binding proteins, a 2D-SDS-PAGE ligand blotting was performed, and recognized spots were identified by MS/MS. Seven proteins from T. solium cysticerci were found capable of binding Plg: fascicilin-1, fasciclin-2, enolase, MAPK, annexin, actin, and cytosolic malate dehydrogenase. To determine whether rTsEnoA binds human Plg, a ligand blotting was performed and the results were confirmed by ELISA both in the presence and absence of εACA, a competitive Plg inhibitor. Finally, rTsEnoA-bound Plg was activated to plasmin in the presence of tPA. To better understand the evolution of enolase isoforms in T. solium, a phylogenetic inference analysis including 75 enolase amino acid sequences was conducted. The origin of flatworm enolase isoforms, except for Eno4, is independent of their vertebrate counterparts. Therefore, herein we propose to designate tapeworm protein isoforms as A, B, C, and 4. In conclusion, recombinant enolase showed a strong plasminogen binding and activating activity in vitro. T. solium enolase could play a role in parasite invasion along with other plasminogen-binding proteins.

HLA typing using genome wide data reveals susceptibility types for infections in a psychiatric disease enriched sample

BACKGROUND

The infections Toxoplasma gondii (T. gondii), cytomegalovirus, and Herpes Simplex Virus Type 1 (HSV1) are common persistent infections that have been associated with schizophrenia and bipolar disorder. The major histocompatibility complex (MHC, termed HLA in humans) region has been implicated in these infections and these mental illnesses. The interplay of MHC genetics, mental illness, and infection has not been systematically examined in previous research.

METHODS

In a cohort of 1636 individuals, we used genome-wide association data to impute 7 HLA types (A, B, C, DRB1, DQA1, DQB1, DPB1), and combined this data with serology data for these infections. We used regression analysis to assess the association between HLA alleles, infections (individually and collectively), and mental disorder status (schizophrenia, bipolar disorder, controls).

RESULTS

After Bonferroni correction for multiple comparisons, HLA C∗07:01 was associated with increased HSV1 infection among mentally healthy controls (OR 3.4, p = 0.0007) but not in the schizophrenia or bipolar groups (P > 0.05). For the multiple infection outcome, HLA B∗ 38:01 and HLA C∗12:03 were protective in the healthy controls (OR ≈ 0.4) but did not have a statistically-significant effect in the schizophrenia or bipolar groups. T. gondii had several nominally-significant positive associations, including the haplotypes HLA DRB∗03:01 ∼ HLA DQA∗05:01 ∼ HLA DQB∗02:01 and HLA B∗08:01 ∼ HLA C∗07:01.

CONCLUSIONS

We identified HLA types that showed strong and significant associations with neurotropic infections. Since some of these associations depended on mental illness status, the engagement of HLA-related pathways may be altered in schizophrenia due to immunogenetic differences or exposure history.

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.