Toxoplasma gondii

TgMIC6 inhibition of autophagy is partially responsible for the phenotypic differences between Chinese 1 Toxoplasma gondii strains

Chinese1 is the predominant Toxoplasma gondii lineage in China, and significant phenotypic differences are observed within the lineage. WH3 and WH6 are two representative strains of Chinese 1, which exhibit divergent virulence and pathogenicity in mice. However, virulence determinants and their modulating mechanisms remain elusive. A global genome expression analysis of the WH3 and WH6 transcriptional profiles identified microneme secretory protein 6 (MIC6), which may be associated with the phenotypic difference observed in WH3. In the present study, the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 genome-editing technique was used to generate a T. gondii microneme secretory protein (TgMIC6) knockout in WH3. Wild-type mice and different mouse and human cell lines were infected with the WH3, WH3-Δmic6, and WH6 strains. The survival rate of mice, related cytokine levels in serum, and the proliferation of parasites were observed. These results suggested that TgMIC6 is an important effector molecule that determines the differential virulence of WH3 in vivo and in vitro. Furthermore, MIC6 may enhance WH3 virulence via inhibition of host cell autophagy and activation of key molecules in the epidermal growth factor receptor (EGFR)-Akt-mammalian target of rapamycin (mTOR) classical autophagy pathway. CD40L was cleared in vivo by i.p injection of CD40L monoclonal antibody, and it was found that the virulence of WH3-Δmic6 to mice was restored to a certain extent in the absence of CD40L. This study elucidates the virulence determinants and immune escape strategies of Toxoplasma gondii in China. Moreover, these data will aid the development of effective strategies for the prevention and control of toxoplasmosis.

Monoclonal antibodies: From magic bullet to precision weapon

Monoclonal antibodies (mAbs) are used to prevent, detect, and treat a broad spectrum of non-communicable and communicable diseases. Over the past few years, the market for mAbs has grown exponentially with an expected compound annual growth rate (CAGR) of 11.07% from 2024 (237.64 billion USD estimated at the end of 2023) to 2033 (679.03 billion USD expected by the end of 2033). Ever since the advent of hybridoma technology introduced in 1975, antibody-based therapeutics were realized using murine antibodies which further progressed into humanized and fully human antibodies, reducing the risk of immunogenicity. Some benefits of using mAbs over conventional drugs include a drastic reduction in the chances of adverse reactions, interactions between drugs, and targeting specific proteins. While antibodies are very efficient, their higher production costs impede the process of commercialization. However, their cost factor has been improved by developing biosimilar antibodies as affordable versions of therapeutic antibodies. Along with the recent advancements and innovations in antibody engineering have helped and will furtherly help to design bio-better antibodies with improved efficacy than the conventional ones. These novel mAb-based therapeutics are set to revolutionize existing drug therapies targeting a wide spectrum of diseases, thereby meeting several unmet medical needs. This review provides comprehensive insights into the current fundamental landscape of mAbs development and applications and the key factors influencing the future projections, advancement, and incorporation of such promising immunotherapeutic candidates as a confrontation approach against a wide list of diseases, with a rationalistic mentioning of any limitations facing this field.

Associations between Fetal Symptoms during Pregnancy and Neonatal Clinical Complications with Toxoplasmosis

INTRODUCTION

Toxoplasmosis is a parasitism transmitted by Toxoplasma gondii, part of the TORCH complex, the most prevalent parasitism worldwide. It is asymptomatic in immunocompetent individuals but causes severe infections and developmental abnormalities in pregnant women, mainly affecting the central nervous system and the gastrointestinal system.

METHODS

In our prospective study, we analyzed cases of recent maternal Toxoplasma infections confirmed by serological testing between 1996 and 2020 at the Department of Obstetrics and Gynecology, Semmelweis University. Amniocentesis, followed by PCR, was performed in cases of recent infection confirmed by serological testing during pregnancy. After birth, a neonatological, microbiological, pediatric neurological and ophthalmological examination and a follow-up was carried out.

RESULTS

During the study period, a total of 238 cases of amniotic fluid Toxoplasma PCR testing due to Toxoplasma recent infection were performed. In terms of pregnancies, there were 219 deliveries and seven abortions. Twelve cases had no data available on the outcome of the pregnancy. In total, 133 cases of ultrasound abnormalities were detected during pregnancy, while in 105 cases, no abnormalities were detected on ultrasound examination. During amniocentesis, eight cases of Toxoplasma infection were revealed in amniotic fluid samples by PCR, and in 230 cases, the result was negative. Neonatal follow-up was performed in 139 cases, with no abnormalities during follow-up in 117 cases, and in 22 cases, there was a detectable complication that was likely to be related to Toxoplasma infection. In all 22 cases, amniotic fluid PCR Toxoplasma testing was negative.

CONCLUSIONS

The most common ultrasound abnormalities involve the nervous system and the gastrointestinal system. In cases of suspicion, it is recommended to perform amniocentesis Toxoplasma PCR testing besides the indirect methods to help the pregnant woman decide whether to carry the pregnancy to term. During follow-up, a multidisciplinary team experienced in pregnancies complicated by toxoplasmosis must carry out the follow-up, care and subsequent development.

4D label-free proteomic analysis reveals key potential pathways of Toxoplasma invasion into the central nervous system

Toxoplasma gondii is a successful parasite capable of infecting a wide range of warm-blooded animals, including people, livestock, and wildlife. In individuals with intact immune function, T. gondii can invade the host brain tissue by altering the blood-brain barrier permeability, leading to chronic infection. Proteins play crucial regulatory roles in disease progression. By monitoring changes in proteins, a deeper understanding of the molecular mechanisms underlying host resistance to infection and the potential pathogenic mechanisms of pathogens can be gained. This study analyzed differential protein expression and associated signaling pathways in mouse brain tissues during acute and chronic T. gondii infection using proteomic and bioinformatics methods. The results showed that during acute and chronic T. gondii infection stages, 74 and 498 differentially expressed proteins (DEPs) were identified in mouse brain tissue, respectively. Among them, 45 and 309 were up-regulated, while 29 and 189 were down-regulated. GO and KEGG analyses revealed that some of these DEPs were implicated in host immunity, pathogen immune evasion, and T. gondii invasion of the central nervous system, particularly interleukin production and secretion, complement system activation, and alterations in tight junction pathways. Notably, the upregulation of Rab13 was identified as a potential molecular mechanism for T. gondii to regulate blood-brain barrier permeability and facilitate central nervous system invasion. Our findings provided fundamental data for understanding host control of Toxoplasmosis infection and offered new insights into parasite immune evasion and invasion mechanisms within the central nervous system. These insights are crucial for developing strategies to prevent the establishment of chronic T. gondii infection.

Assessment of Knowledge, Attitude, and Preventive Behavior Regarding Toxoplasmosis among Females in Riyadh, Saudi Arabia: A Cross-Sectional Study

Toxoplasmosis, a prevalent parasitic zoonotic disease, is influenced by various factors such as the climate, dietary habits, and hygiene practices. This study aimed to evaluate the knowledge, attitudes, and preventive behaviors regarding toxoplasmosis among females in Riyadh, Saudi Arabia. Utilizing a bilingual Google form, a cross-sectional online survey was distributed in both Arabic and English, and it was conducted between 11 January 2024 and 4 March 2024. Statistical analysis was conducted using SPSS Version 27, with a p-value ≤ 0.05 indicating significant qualitative data. The data were analyzed using descriptive statistics and the chi-square test. A total of 533 participants were included in the study. Participants aged 18-25 years old constituted the largest group (70.4%), with those aged 26-40 years old accounting for 14.4% and ages 41-60 years old comprising 15.2%. Among the participants, 76.4% were unmarried, and 21.4% were pregnant. Notably, 79.2% of participants reported being unaware of toxoplasmosis, with only 9.0% gaining awareness from doctors and a mere 3.6% from awareness campaigns. Any understanding of the disease's severity and causative factors was limited to 15.9%. Despite a generally positive attitude towards preventive measures, significant correlations were found between toxoplasmosis and age (p-value 0.093), as well as the consumption of medium-cooked meat (p-value 0.008). Other variables, such as social status, cat ownership, handwashing before meals, and washing fruits and vegetables did not show significant correlations. Diet and hygiene practices notably impact toxoplasmosis transmission. In Riyadh, 79% of participants did not own cats, and 67.7% avoided undercooked meat. However, 6.7% used unfiltered water, and 8.4% did not wash their hands after handling raw meat and vegetables. The study concludes that there is insufficient knowledge regarding toxoplasmosis among females in Riyadh. Despite low knowledge, there is a neutral to slightly positive attitude and a willingness to learn and adopt preventive measures when informed. With better education, attitudes towards toxoplasmosis could improve due to a desire to learn and act. While general hygiene practices were favorable, specific preventive behaviors for toxoplasmosis need enhancement to reduce infection risks.

Seroepidemiological study on coinfection of toxoplasmosis and active tuberculosis in Northern Iran: a case control study

Coinfection of tuberculosis (TB) and human parasitic infections is common in developing countries. There is little information about the prevalence of Toxoplasma gondii (T. gondii) infection among TB patients in Iran. In this case-control study, anti-toxoplasma antibodies were measured by ELISA method in 100 patients with active tuberculosis and 100 healthy individuals who were matched in terms of sex, age, and place of residence. Anti-T. gondii IgG antibodies were diagnosed in 62% of TB patients (95% CI 53-71%) and 70% of control subjects (95% CI 62-78%). Anti-T. gondii IgM antibodies were found in 1% of both TB patients and control group. The seroprevalence of T. gondii infection was not significantly different between TB patients and healthy individuals (P > 0.05). None of the assessed sociodemographic and behavioral factors was recognized as a risk factor for toxoplasmosis in TB infected patients. Moreover, the level of anti-T. gondii IgG antibodies concentration in TB patients was significantly higher than in control subjects and revealed skewness towards humoral immune response in TB patients. Coinfection of toxoplasmosis and tuberculosis was prevalent but T. gondii infection was independent of active TB in this co-endemic area.

Decidual natural killer cells dysfunction is caused by IDO downregulation in dMDSCs with Toxoplasma gondii infection

Myeloid-derived suppressor cells (MDSCs) play a crucial role in maintaining maternal-fetal tolerance by expressing some immune-suppressive molecules, such as indoleamine 2,3-dioxygenase (IDO). Toxoplasma gondii (T. gondii) infection can break the immune microenvironment of maternal-fetal interface, resulting in adverse pregnancy outcomes. However, whether T. gondii affects IDO expression in dMDSCs and the molecular mechanism of its effect are still unclear. Here we show, the mRNA level of IDO is increased but the protein level decreased in infected dMDSCs. Mechanistically, the upregulation of transcriptional levels of IDO in dMDSCs is regulated through STAT3/p52-RelB pathway and the decrease of IDO expression is due to its degradation caused by increased SOCS3 after T. gondii infection. In vivo, the adverse pregnancy outcomes of IDO-/- infected mice are more severe than those of wide-type infected mice and obviously improved after exogenous kynurenine treatment. Also, the reduction of IDO in dMDSCs induced by T. gondii infection results in the downregulation of TGF-β and IL-10 expression in dNK cells regulated through Kyn/AhR/SP1 signal pathway, eventually leading to the dysfunction of dNK cells and contributing the occurrence of adverse pregnancy outcomes. This study reveals a novel molecular mechanism in adverse pregnancy outcome induced by T. gondii infection.

AP2XII-1 and AP2XI-2 Suppress Schizogony Gene Expression in Toxoplasma gondii

Toxoplasma gondii is an intracellular parasite that is important in medicine and veterinary science and undergoes distinct developmental transitions in its intermediate and definitive hosts. The switch between stages of T. gondii is meticulously regulated by a variety of factors. Previous studies have explored the role of the microrchidia (MORC) protein complex as a transcriptional suppressor of sexual commitment. By utilizing immunoprecipitation and mass spectrometry, constituents of this protein complex have been identified, including MORC, Histone Deacetylase 3 (HDAC3), and several ApiAP2 transcription factors. Conditional knockout of MORC or inhibition of HDAC3 results in upregulation of a set of genes associated with schizogony and sexual stages in T. gondii tachyzoites. Here, our focus extends to two primary ApiAP2s (AP2XII-1 and AP2XI-2), demonstrating their significant impact on the fitness of asexual tachyzoites and their target genes. Notably, the targeted disruption of AP2XII-1 and AP2XI-2 resulted in a profound alteration in merozoite-specific genes targeted by the MORC-HDAC3 complex. Additionally, considerable overlap was observed in downstream gene profiles between AP2XII-1 and AP2XI-2, with AP2XII-1 specifically binding to a subset of ApiAP2 transcription factors, including AP2XI-2. These findings reveal an intricate cascade of ApiAP2 regulatory networks involved in T. gondii schizogony development, orchestrated by AP2XII-1 and AP2XI-2. This study provides valuable insights into the transcriptional regulation of T. gondii growth and development, shedding light on the intricate life cycle of this parasitic pathogen.

Drug repurposing for parasitic protozoan diseases

Protozoan parasites are major hazards to human health, society, and the economy, especially in equatorial regions of the globe. Parasitic diseases, including leishmaniasis, malaria, and others, contribute towards majority of morbidity and mortality. Around 1.1 million people die from these diseases annually. The lack of licensed vaccinations worsens the worldwide impact of these diseases, highlighting the importance of safe and effective medications for their prevention and treatment. However, the appearance of drug resistance in parasites continuously affects the availability of medications. The demand for novel drugs motivates global antiparasitic drug discovery research, necessitating the implementation of many innovative ways to maintain a continuous supply of promising molecules. Drug repurposing has come out as a compelling tool for drug development, offering a cost-effective and efficient alternative to standard de novo approaches. A thorough examination of drug repositioning candidates revealed that certain drugs may not benefit significantly from their original indications. Still, they may exhibit more pronounced effects in other disorders. Furthermore, certain medications can produce a synergistic effect, resulting in enhanced therapeutic effectiveness when given together. In this chapter, we outline the approaches employed in drug repurposing (sometimes referred to as drug repositioning), propose novel strategies to overcome these hurdles and fully exploit the promise of drug repurposing. We highlight a few major human protozoan diseases and a range of exemplary drugs repurposed for various protozoan infections, providing excellent outcomes for each disease.

Metabolic plasticity, essentiality and therapeutic potential of ribose-5-phosphate synthesis in Toxoplasma gondii

Ribose-5-phosphate (R5P) is a precursor for nucleic acid biogenesis; however, the importance and homeostasis of R5P in the intracellular parasite Toxoplasma gondii remain enigmatic. Here, we show that the cytoplasmic sedoheptulose-1,7-bisphosphatase (SBPase) is dispensable. Still, its co-deletion with transaldolase (TAL) impairs the double mutant's growth and increases 13C-glucose-derived flux into pentose sugars via the transketolase (TKT) enzyme. Deletion of the latter protein affects the parasite's fitness but is not lethal and is correlated with an increased carbon flux via the oxidative pentose phosphate pathway. Further, loss of TKT leads to a decline in 13C incorporation into glycolysis and the TCA cycle, resulting in a decrease in ATP levels and the inability of phosphoribosyl-pyrophosphate synthetase (PRPS) to convert R5P into 5'-phosphoribosyl-pyrophosphate and thereby contribute to the production of AMP and IMP. Likewise, PRPS is essential for the lytic cycle. Not least, we show that RuPE-mediated metabolic compensation is imperative for the survival of the ΔsbpaseΔtal strain. In conclusion, we demonstrate that multiple routes can flexibly supply R5P to enable parasite growth and identify catalysis by TKT and PRPS as critical enzymatic steps. Our work provides novel biological and therapeutic insights into the network design principles of intracellular parasitism in a clinically-relevant pathogen.

RPA-CRISPR/Cas9-based method for the detection of Toxoplasma gondii: A proof of concept

Toxoplasma gondii is a widespread and specialized intracellular protozoan pathogen that affects one third of the world' s population, posing a great threat to public health. As the definitive host, cats excrete oocysts and play a crucial role in the transmission of toxoplasmosis. The current diagnostic tools usually require bulky equipment and expertize, which hinders the efficient diagnosis and intervention of Toxoplasma infection in cats. In this study, we combined (RPA) with clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technique to establish an easier method for the detection of T. gondii oocysts in cat fecal samples. The sensitivity, specificity, and practicability of the established RPA-CRISPR/Cas9 method were evaluated using a lateral flow strip, with the limitation of detection determined at 10 plasmid copies/μL (corresponding to about one oocyst), cross reactivity to none of Giardia lamblia, Cryptosporidium sp., Microsporidium biberi and Blastocystis hominis that also commonly found in cats, and comparable performance in detecting T. gondii in clinical samples to conventional PCR amplification. This RPA-CRISPR/Cas9 method provides an alternative to conventional molecular tools used in the clinical diagnosis of Toxoplasma infection in cats and other animals.

Toxoplasma gondii eIF-5A Modulates the Immune Response of Murine Macrophages In Vitro

Toxoplasma gondii (T. gondii) is an obligate intracellular protozoan that can elicit a robust immune response during infection. Macrophage cells have been shown to play an important role in the immune response against T. gondii. In our previous study, the eukaryotic translation initiation factor 5A (eIF-5A) gene of T. gondii was found to influence the invasion and replication of tachyzoites. In this study, the recombinant protein of T. gondii eIF-5A (rTgeIF-5A) was incubated with murine macrophages, and the regulatory effect of TgeIF-5A on macrophages was characterized. Immunofluorescence assay showed that TgeIF-5A was able to bind to macrophages and partially be internalized. The Toll-like receptor 4 (TLR4) level and chemotaxis of macrophages stimulated with TgeIF-5A were reduced. However, the phagocytosis and apoptosis of macrophages were amplified by TgeIF-5A. Meanwhile, the cell viability experiment indicated that TgeIF-5A can promote the viability of macrophages, and in the secretion assays, TgeIF-5A can induce the secretion of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and nitric oxide (NO) from macrophages. These findings demonstrate that eIF-5A of T. gondii can modulate the immune response of murine macrophages in vitro, which may provide a reference for further research on developing T. gondii vaccines.

Proteomics analysis of Toxoplasma gondii merozoites reveals regulatory proteins involved in sexual reproduction

Sexual reproduction plays a crucial role in the transmission and life cycle of toxoplasmosis. The merozoites are the only developmental stage capable of differentiation into male and female gametes, thereby initiating sexual reproduction to form oocysts that are excreted into the environment. Hence, our study aimed to perform proteomic analyses of T. gondii Pru strain merozoites, a pre-sexual developmental stage in cat IECs, and tachyzoites, an asexual developmental stage, using the tandem mass tag (TMT) method in order to identify the differentially expressed proteins (DEPs) of merozoites. Proteins functions were subjected to cluster analysis, and DEPs were validated through the qPCR method. The results showed that a total of 106 proteins were identified, out of which 85 proteins had quantitative data. Among these, 15 proteins were differentially expressed within merozoites, with four exhibiting up-regulation and being closely associated with the material and energy metabolism as well as the cell division of T. gondii. Two novel DEPs, namely S8GHL5 and A0A125YP41, were identified, and their homologous family members have been demonstrated to play regulatory roles in oocyte maturation and spermatogenesis in other species. Therefore, they may potentially exhibit regulatory functions during the differentiation of micro- and macro-gametophytes at the initiation stage of sexual reproduction in T. gondii. In conclusion, our results showed that the metabolic and divisional activities in the merozoites surpass those in the tachyzoites, thereby providing structural, material, and energetic support for gametophytes development. The discovery of two novel DEPs associated with sexual reproduction represents a significant advancement in understanding Toxoplasma sexual reproduction initiation and oocyst formation.

Mineralization Reduces the Toxicity and Improves Stability and Protective Immune Response Induced by Toxoplasma gondii

Vaccination is an ideal strategy for the control and prevention of toxoplasmosis. However, the thermostability and effectiveness of vaccines limit their application. Here, calcium mineralization was used to fabricate Toxoplasma gondii tachyzoites as immunogenic core-shell particles with improved immune response and thermostability. In the current study, T. gondii RH particles coated with mineralized shells were fabricated by calcium mineralization. The mineralized shells could maintain the T. gondii tachyzoites structural integrity for at least 12 months and weaken the virulence. Immunization of mice with mineralized tachyzoites induced high levels of T. gondii-specific antibodies and cytokines. The immunized mice were protected with a 100% survival rate in acute and chronic infection, and brain cyst burdens were significantly reduced. This study reported for the first time the strategy of calcium mineralization on T. gondii and proved that mineralized tachyzoites could play an immune protective role, thus expanding the application of biomineralization in T. gondii vaccine delivery.

Potential Anti-Toxoplasmosis Efficiency of Phoenix dactylifera Extracts Loaded on Selenium Nanoparticles

Background

Toxoplasmosis is a parasitic disease caused by Toxoplasma gondii that infects humans and many types of mammals and birds.

Objective

To investigate the effect of selenium nanoparticles (SeNPs) and Phoenix dactylifera (Pd) extracts loaded on SeNPs as a new agent to combat chronic T. gondii infections in murine model as an alternative method to standard Spiramycin drug therapy.

Methods

A total of 64 female mice were randomly divided into eight groups: GI: Normal control, GII: Positive control, GIII: infected and treated with Spiramycin, GIV: infected and treated with SeNPs, GV: infected and treated with aqueous extract of Pd, GVI: infected and treated with methanolic extract of Pd, GVII: infected and treated with aqueous extract of Pd loaded on SeNPs, GVIII: infected and treated with methanolic extract of Pd loaded on SeNPs. Date palm (P. dactylifera) fruits were identified and collected from the farms of Saudi Arabia. Preparation and characterization of SeNPs were done. The parasitological, histopathological examinations and biochemical changes were evaluated in all groups.

Results

Parasitological results showed significant differences in GVII in comparison to GII while GVIII showed significant differences in comparison to GII and GIII. The histopathological section of the cerebral cortex showed obvious alterations in the infected compared with untreated control groups. Aqueous and methanolic extracts of P. dactylifera loaded on SeNPs treatment showed improvement that indicated by few perivascular cuffing with few inflammatory cell infiltrations. Few granule cells with mild intracellular vacuolation and edema few deformed neurons with deep pyknotic nuclei. Microglia cells expression of Iba-1 and inflammatory cytokines (IL-4, IL-10 and INF-γ) in serum of all groups was higher in GII and lowest in GVIII followed by GVII.

Conclusion

SeNPs and P. dactylifera extracts loaded on SeNPs could be a potent agent to combat T. gondii infections.

Gut microbiota-related metabolite alpha-linolenic acid mitigates intestinal inflammation induced by oral infection with Toxoplasma gondii

BACKGROUND

Oral infection with cysts is the main transmission route of Toxoplasma gondii (T. gondii), which leads to lethal intestinal inflammation. It has been widely recognized that T. gondii infection alters the composition and metabolism of the gut microbiota, thereby affecting the progression of toxoplasmosis. However, the potential mechanisms remain unclear. In our previous study, there was a decrease in the severity of toxoplasmosis after T. gondii α-amylase (α-AMY) was knocked out. Here, we established mouse models of ME49 and Δα-amy cyst infection and then took advantage of 16S rRNA gene sequencing and metabolomics analysis to identify specific gut microbiota-related metabolites that mitigate T. gondii-induced intestinal inflammation and analyzed the underlying mechanism.

RESULTS

There were significant differences in the intestinal inflammation between ME49 cyst- and Δα-amy cyst-infected mice, and transferring feces from mice infected with Δα-amy cysts into antibiotic-treated mice mitigated colitis caused by T. gondii infection. 16S rRNA gene sequencing showed that the relative abundances of gut bacteria, such as Lactobacillus and Bacteroides, Bifidobacterium, [Prevotella], Paraprevotella and Macellibacteroides, were enriched in mice challenged with Δα-amy cysts. Spearman correlation analysis between gut microbiota and metabolites indicated that some fatty acids, including azelaic acid, suberic acid, alpha-linolenic acid (ALA), and citramalic acid, were highly positively correlated with the identified bacterial genera. Both oral administration of ALA and fecal microbiota transplantation (FMT) decreased the expression of pro-inflammatory cytokines and restrained the MyD88/NF-κB pathway, which mitigated colitis and ultimately improved host survival. Furthermore, transferring feces from mice treated with ALA reshaped the colonization of beneficial bacteria, such as Enterobacteriaceae, Proteobacteria, Shigella, Lactobacillus, and Enterococcus.

CONCLUSIONS

The present findings demonstrate that the host gut microbiota is closely associated with the severity of T. gondii infection. We provide the first evidence that ALA can alleviate T. gondii-induced colitis by improving the dysregulation of the host gut microbiota and suppressing the production of pro-inflammatory cytokines via the MyD88/NF-κB pathway. Our study provides new insight into the medical application of ALA for the treatment of lethal intestinal inflammation caused by Toxoplasma infection. Video Abstract.

Effect of arctigenin on neurological diseases: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Arctium lappa L. is a common specie of Asteraceae. Its main active ingredient, Arctigenin (AG), in mature seeds exerts pharmacological effects on the Central Nervous System (CNS).

AIM OF THE STUDY

To review studies on the specific effects of the AG mechanism on various CNS diseases and elucidate signal transduction mechanisms and their pharmacological actions.

MATERIALS AND METHODS

This investigation reviewed the essential role of AG in treating neurological disorders. Basic information on Arctium lappa L. was retrieved from the Pharmacopoeia of the People's Republic of China. The related articles from 1981 to 2022 on the network database (including CNKI, PubMed, and Wan Fang and so on) were reviewed using AG and CNS diseases-related terms such as Arctigenin and Epilepsy.

RESULTS

It was confirmed that AG has a therapeutic effect on Alzheimer's disease, Glioma, infectious CNS diseases (such as Toxoplasma and Japanese Encephalitis Virus), Parkinson's disease, Epilepsy, etc. In these diseases, related experiments such as a Western blot analysis revealed that AG could alter the content of some key factors (such as the reduction of Aβ in Alzheimer's disease). However, in-vivo AG's metabolic process and possible metabolites are still undetermined.

CONCLUSION

Based on this review, the existing pharmacological research has indeed made objective progress to elucidate how AG prevents and treats CNS diseases, especially senile degenerative disease such as Alzheimer's diseases. It was revealed that AG could be used as a potential nervous system drug as it has a wide range of effects in theory with markedly high application value, especially in the elder group. However, the existing studies are limited to in-vitro experiments; therefore, little is known about how AG metabolizes and functions in-vivo, limiting its clinical application and requiring further research.

Multiomics and bioinformatics identify differentially expressed effectors in the brain of Toxoplasma gondii infected masked palm civet

Introduction

The masked palm civet (Paguma larvata) serves as a reservoir in transmitting pathogens, such as Toxoplasma gondii, to humans. However, the pathogenesis of T. gondii infection in masked palm civets has not been explored. We studied the molecular changes in the brain tissue of masked palm civets chronically infected with T. gondii ME49.

Methods

The differentially expressed proteins in the brain tissue were investigated using iTRAQ and bioinformatics.

Results

A total of 268 differential proteins were identified, of which 111 were upregulated and 157 were downregulated. KEGG analysis identified pathways including PI3K-Akt signaling pathway, proteoglycans in cancer, carbon metabolism, T-cell receptor signaling pathway. Combing transcriptomic and proteomics data, we identified 24 genes that were differentially expressed on both mRNA and protein levels. The top four upregulated proteins were REEP3, REEP4, TEP1, and EEPD1, which was confirmed by western blot and immunohistochemistry. KEGG analysis of these 24 genes identified signaling cascades that were associated with small cell lung cancer, breast cancer, Toll-like receptor signaling pathway, Wnt signaling pathways among others. To understand the mechanism of the observed alteration, we conducted immune infiltration analysis using TIMER databases which identified immune cells that are associated with the upregulation of these proteins. Protein network analysis identified 44 proteins that were in close relation to all four proteins. These proteins were significantly enriched in immunoregulation and cancer pathways including PI3K-Akt signaling pathway, Notch signaling pathway, chemokine signaling pathway, cell cycle, breast cancer, and prostate cancer. Bioinformatics utilizing two cancer databases (TCGA and GEPIA) revealed that the four genes were upregulated in many cancer types including glioblastoma (GBM). In addition, higher expression of REEP3 and EEPD1 was associated with better prognosis, while higher expression of REEP4 and TEP1 was associated with poor prognosis in GBM patients.

Discussion

We identified the differentially expressed genes in the brain of T. gondii infected masked palm civets. These genes were associated with various cellular signaling pathways including those that are immune- and cancer-related.

Iron-overload-induced ferroptosis in mouse cerebral toxoplasmosis promotes brain injury and could be inhibited by Deferiprone

Iron is a trace metal element that is essential for the survival of cells and parasites. The role of iron in cerebral toxoplasmosis (CT) is still unclear. Deferiprone (DFP) is the orally active iron chelator that binds iron in a molar ratio of 3:1 (ligand:iron) and promotes urinary iron excretion to remove excess iron from the body. The aims of this experiment were to observe the alterations in iron in brains with Toxoplasma gondii (T. gondii) acute infections and to investigate the mechanism of ferroptosis in CT using DFP. We established a cerebral toxoplasmosis model in vivo using TgCtwh3, the dominant strains of which are prevalent in China, and treated the mice with DFP at a dose of 75 mg/kg/d. Meanwhile, we treated the HT-22 cells with 100 μM DFP for half an hour and then infected cells with TgCtwh3 in vitro. A qRT-PCR assay of TgSAG1 levels showed a response to the T. gondii burden. We used inductively coupled plasma mass spectrometry, an iron ion assay kit, Western blot analysis, glutathione and glutathione disulfide assay kits, a malonaldehyde assay kit, and immunofluorescence to detect the ferroptosis-related indexes in the mouse hippocampus and HT-22 cells. The inflammatory factors interferon-γ, tumor necrosis factor-α, transforming growth factor-β, and arginase 1 in the hippocampus and cells were detected using the Western blot assay. Hematoxylin and eosin staining, electron microscopy, and the Morris water maze experiment were used to evaluate the brain injuries of the mice. The results showed that TgCtwh3 infection is followed by the activation of ferroptosis-related signaling pathways and hippocampal pathological damage in mice. The use of DFP led to ferroptosis resistance and attenuated pathological changes, inflammatory reactions and T. gondii burden of the mice, prolonging their survival time. The HT-22 cells with TgCtwh3 activated the ferroptosis pathway and was inhibit by DFP in vitro. In TgCtwh3-infected cells, inflammatory response and mitochondrial damage were severe, but these effects could be reduced by DFP. Our study elucidates the mechanism by which T. gondii interferes with the host's iron metabolism and activates ferroptosis, complementing the pathogenic mechanism of CT and further demonstrating the potential value of DFP for the treatment of CT.

ROP16 of Toxoplasma gondii Inhibits Innate Immunity by Triggering cGAS-STING Pathway Inactivity through the Polyubiquitination of STING

cGAS-STING signaling is a major pathway in inducing type Ⅰ IFN, which plays a crucial role in the defense against T. gondii infection. In contrast, T. gondii develops multiple strategies to counteract the host defense, causing serious diseases in a wide range of hosts. Here, we demonstrate that T. gondii rhoptry protein 16 (ROP16) dampens type I interferon signaling via the inhibition of the cGAS (cyclic GMP-AMP synthase) pathway through the polyubiquitination of STING. Mechanistically, ROP16 interacts with STING through the SignalP domain and inhibits the K63-linked ubiquitination of STING in an NLS (nuclear localization signal)-domain-dependent manner. Consequently, knocking out the ROP16 in PRU tachyzoites promotes the STING-mediated production of type I IFNs and limits the replication of T. gondii. Together, these findings describe a distinct pathway where T. gondii exploits the ubiquitination of STING to evade host anti-parasite immunity, revealing new insights into the interaction between the host and parasites.

Mitochondrial ADP/ATP Carrier 1 Is Important for the Growth of Toxoplasma Tachyzoites

Metabolism associated with energy production is highly compartmentalized in eukaryotic cells. During this process, transporters that move metabolites across organelle membranes play pivotal roles. The highly conserved ADP/ATP carrier (AAC) involved in ATP and ADP exchange between the mitochondria and cytoplasm is key to linking the metabolic activities in these 2 compartments. The ATP produced in mitochondria can be exchanged with cytoplasmic ADP by AAC, thus satisfying the energy needs in the cytoplasm. Toxoplasma gondii is an obligate intracellular parasite with a wide range of hosts. Previous studies have shown that mitochondrial metabolism helps Toxoplasma to parasitize diverse host cells. Here, we identified 2 putative mitochondria ADP/ATP carriers in Toxoplasma with significant sequence similarity to known AACs from other eukaryotes. We examined the ATP transport function of TgAACs by expressing them in Escherichia coli cells and found that only TgAAC1 had ATP transport activity. Moreover, knockdown of TgAAC1 caused severe growth defects of parasites and heterologous expression of mouse ANT2 in the TgAAC1 depletion mutant restored its growth, revealing its importance for parasite growth. These results verified that TgAAC1 functions as the mitochondrial ADP/ATP carrier in T. gondii and the functional studies demonstrated the importance of TgAAC1 for tachyzoites growth. IMPORTANCE T. gondii has an efficient and flexible energy metabolism system to meet different growth needs. ATP is an energy-carrying molecule and needs to be exchanged between organelles with the assistance of transporters. However, the function of TgAACs has yet to be characterized. Here, we identified 2 putative AACs of T. gondii and verified that only TgAAC1 had ATP transport activity with expression in the intact E. coli cells. Detailed analyses found that TgAAC1 is critical for the growth of tachyzoites and TgAAC2 is dispensable. Moreover, complementation with mouse ANT2 restored the growth speed of iTgAAC1, further suggesting TgAAC1 functions as a mitochondrial ADP/ATP carrier. Our research demonstrated the importance of TgAAC1 for tachyzoites growth.

Computational screening of FDA-approved drugs to identify potential TgDHFR, TgPRS, and TgCDPK1 proteins inhibitors against Toxoplasma gondii

Toxoplasma gondii (T. gondii) is one of the most successful parasites in the world, because about a third of the world's population is seropositive for toxoplasmosis. Treatment regimens for toxoplasmosis have remained unchanged for the past 20 years, and no new drugs have been introduced to the market recently. This study, performed molecular docking to identify interactions of FDA-approved drugs with essential residues in the active site of proteins of T. gondii Dihydrofolate Reductase (TgDHFR), Prolyl-tRNA Synthetase (TgPRS), and Calcium-Dependent Protein Kinase 1 (TgCDPK1). Each protein was docked with 2100 FDA-approved drugs using AutoDock Vina. Also, the Pharmit software was used to generate pharmacophore models based on the TgDHFR complexed with TRC-2533, TgPRS in complex with halofuginone, and TgCDPK1 in complex with a bumped kinase inhibitor, RM-1-132. Molecular dynamics (MD) simulation was also performed for 100 ns to verify the stability of interaction in drug-protein complexes. Molecular Mechanics Poisson-Boltzmann Surface Area (MMPBSA) analysis evaluated the binding energy of selected complexes. Ezetimibe, Raloxifene, Sulfasalazine, Triamterene, and Zafirlukast drugs against the TgDHFR protein, Cromolyn, Cefexim, and Lactulose drugs against the TgPRS protein, and Pentaprazole, Betamethasone, and Bromocriptine drugs against TgCDPK1 protein showed the best results. These drugs had the lowest energy-based docking scores and also stable interactions based on MD analyses with TgDHFR, TgPRS, and TgCDPK1 drug targets that can be introduced as possible drugs for laboratory investigations to treat T. gondii parasite infection.

Two small-molecule inhibitors of Toxoplasma gondii proliferation in vitro

Background

Toxoplasmosis caused by Toxoplasma gondii is a globally distributed zoonosis. Most infections appear asymptomatic in immunocompetent individuals, but toxoplasmosis can be fatal in fetuses and immunocompromised adults. There is an urgent need to research and develop effective and low-toxicity anti-T. gondii drugs because of some defects in current clinical anti-T. gondii drugs, such as limited efficacy, serious side effects and drug resistance.

Methods

In this study, 152 autophagy related compounds were evaluated as anti-T. gondii drugs. The activity of β-galactosidase assay based on luminescence was used to determine the inhibitory effect on parasite growth. At the same time, MTS assay was used to further detect the effects of compounds with over 60% inhibition rate on host cell viability. The invasion, intracellular proliferation, egress and gliding abilities of T. gondii were tested to assess the inhibitory effect of the chosen drugs on the distinct steps of the T. gondii lysis cycle.

Results

The results showed that a total of 38 compounds inhibited parasite growth by more than 60%. After excluding the compounds affecting host cell activity, CGI-1746 and JH-II-127 were considered for drug reuse and further characterized. Both CGI-1746 and JH-II-127 inhibited tachyzoite growth by 60%, with IC50 values of 14.58 ± 1.52 and 5.88 ± 0.23 μM, respectively. TD50 values were 154.20 ± 20.15 and 76.39 ± 14.32 μM, respectively. Further research found that these two compounds significantly inhibited the intracellular proliferation of tachyzoites. Summarize the results, we demonstrated that CGI-1746 inhibited the invasion, egress and especially the gliding abilities of parasites, which is essential for the successful invasion of host cells, while JH-II-127 did not affect the invasion and gliding ability, but seriously damaged the morphology of mitochondria which may be related to the damage of mitochondrial electron transport chain.

Discussion

Taken together, these findings suggest that both CGI-1746 and JH-II-127 could be potentially repurposed as anti-T. gondii drugs, lays the groundwork for future therapeutic strategies.

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.

Recombinant Toxoplasma gondii Calreticulin protein provides partial protection against acute and chronic toxoplasmosis

Toxoplasma gondii, a highly prevalent apicomplexan pathogen, can cause serious or even fatal toxoplasmosis in both animals and humans. Immunoprophylaxis is considered a promising strategy for controlling this disease. Calreticulin (CRT) is known as a pleiotropic protein, which is critical for calcium storage and phagocytosis of apoptotic cells. Our study examined the protective effects of recombinant T. gondii Calreticulin (rTgCRT) as a recombinant subunit vaccine against the T. gondii challenge in mice. Here, rTgCRT was successfully expressed in vitro using prokaryptic expression system. Polyclonal antibody (pAb) has been prepared by immunizing Sprague Dawley rats with rTgCRT. Western blotting showed that rTgCRT and natural TgCRT protein were recognized by serum of T. gondii infected mice and rTgCRT pAb, respectively. T lymphocyte subsets and antibody response were monitored using flow cytometry and enzyme-linked immunosorbent assay (ELISA). The results showed that ISA 201 rTgCRT could stimulate lymphocyte proliferation and induce high levels of total and subclasses of IgG. After the RH strain challenge, a longer survival period was given by the ISA 201 rTgCRT vaccine compared to the control groups; after infection with the PRU strain, we observed a 100% survival rate and a significant reduction in cysts load and size. In the neutralization test, high concentrations of rat-rTgCRT pAb provided 100% protection, while in the passive immunization trial, only weak protection was observed after RH challenge, indicating that rTgCRT pAb needs further modification to improve its activity in vivo. Taken together, these data confirmed that rTgCRT can trigger strong cellular and humoral immune responses against acute and chronic toxoplasmosis.

Overview of Apoptosis, Autophagy, and Inflammatory Processes in Toxoplasma gondii Infected Cells

Toxoplasma gondii (T. gondii) is an obligate intracellular parasite. During the parasitic invasion, T. gondii creates a parasitophorous vacuole, which enables the modulation of cell functions, allowing its replication and host infection. It has effective strategies to escape the immune response and reach privileged immune sites and remain inactive in a controlled environment in tissue cysts. This current review presents the factors that affect host cells and the parasite, as well as changes in the immune system during host cell infection. The secretory organelles of T. gondii (dense granules, micronemes, and rhoptries) are responsible for these processes. They are involved with proteins secreted by micronemes and rhoptries (MIC, AMA, and RONs) that mediate the recognition and entry into host cells. Effector proteins (ROP and GRA) that modify the STAT signal or GTPases in immune cells determine their toxicity. Interference byhost autonomous cells during parasitic infection, gene expression, and production of microbicidal molecules such as reactive oxygen species (ROS) and nitric oxide (NO), result in the regulation of cell death. The high level of complexity in host cell mechanisms prevents cell death in its various pathways. Many of these abilities play an important role in escaping host immune responses, particularly by manipulating the expression of genes involved in apoptosis, necrosis, autophagy, and inflammation. Here we present recent works that define the mechanisms by which T. gondii interacts with these processes in infected host cells.

Microenvironment pH modified solid dispersion of Toltrazuril as a new strategy to improve the treatment of experimental Apicomplexan infection

The phylum Apicomplexa contains some of the most serious human and veterinary parasites, including Eimeria magna, Toxoplasma gondii, and many others. Toltrazuril (TOL) has activity against multiple stages of Apicomplexan parasites, but its clinical use is limited by low bioavailability. In present study, we prepared one new formulation named the microenvironment pH modified solid dispersion (pH_M-SD), which was composed of three components including Ca(OH)₂, TOL, and PVPk30 with the weight ratio of 1:8:8. In vivo evaluation for bioavailability and efficacy of the pH_M-SD was conducted following oral administration and hypodermic injection. The performance of the pH_M-SD was also contrast to corresponding results of raw material drug and commercial Baycox® to evaluate the advantages for clinical application. The results showed that the bioavailability of prototype TOL and its active metabolites toltrazuril sulfoxide (TOLSO), toltrazuril sulfone (TOLSO₂) in rabbits were improved remarkably after oral administration of the pH_M-SD. The safety of the pH_M-SD via oral administration was adequately verified via the histopathological examination. We subsequently evaluated effects of the pH_M-SD on Eimeria magna oocysts and Toxoplasma gondii tachyzoites. In vivo anti-coccidia efficacy further confirmed that the pH_M-SD could be used as a strategy to minimize the oocyst exposure. In vitro cytotoxicity and anti-Toxoplasma tests showed that the pH_M-SD had little damage to host cells within the concentration of 100 μg/ mL, and the anti-Toxoplasma efficacy was significantly improved compared with TOL. Combined with the above-mentioned experimental results, we conclude that the pH_M-SD maybe a promising candidate for providing better clinical outcomes.

Lactoferrin as a Component of Pharmaceutical Preparations: An Experimental Focus

Lactoferrin is an 80 kDa monomeric glycoprotein that exhibits multitask activities. Lactoferrin properties are of interest in the pharmaceutical field for the design of products with therapeutic potential, including nanoparticles and liposomes, among many others. In antimicrobial preparations, lactoferrin has been included either as a main bioactive component or as an enhancer of the activity and potency of first-line antibiotics. In some proposals based on nanoparticles, lactoferrin has been included in delivery systems to transport and protect drugs from enzymatic degradation in the intestine, favoring the bioavailability for the treatment of inflammatory bowel disease and colon cancer. Moreover, nanoparticles loaded with lactoferrin have been formulated as delivery systems to transport drugs for neurodegenerative diseases, which cannot cross the blood-brain barrier to enter the central nervous system. This manuscript is focused on pharmaceutical products either containing lactoferrin as the bioactive component or formulated with lactoferrin as the carrier considering its interaction with receptors expressed in tissues as targets of drugs delivered via parenteral or mucosal administration. We hope that this manuscript provides insights about the therapeutic possibilities of pharmaceutical Lf preparations with a sustainable approach that contributes to decreasing the resistance of antimicrobials and enhancing the bioavailability of first-line drugs for intestinal chronic inflammation and neurodegenerative diseases.

A novel Toxoplasma gondii TGGT1_316290 mRNA-LNP vaccine elicits protective immune response against toxoplasmosis in mice

Toxoplasma gondii (T. gondii) can infect almost all warm-blooded animals and is a major threat to global public health. Currently, there is no effective drug or vaccine for T. gondii. In this study, bioinformatics analysis on B and T cell epitopes revealed that TGGT1_316290 (TG290) had superior effects compared with the surface antigen 1 (SAG1). TG290 mRNA-LNP was constructed through the Lipid Nanoparticle (LNP) technology and intramuscularly injected into the BALB/c mice, and its immunogenicity and efficacy were explored. Analysis of antibodies, cytokines (IFN-γ, IL-12, IL-4, and IL-10), lymphocytes proliferation, cytotoxic T lymphocyte activity, dendritic cell (DC) maturation, as well as CD4⁺ and CD8⁺ T lymphocytes revealed that TG290 mRNA-LNP induced humoral and cellular immune responses in vaccinated mice. Furthermore, T-Box 21 (T-bet), nuclear factor kappa B (NF-kB) p65, and interferon regulatory factor 8 (IRF8) subunit were over-expressed in the TG290 mRNA-LNP-immunized group. The survival time of mice injected with TG290 mRNA-LNP was significantly longer (18.7 ± 3 days) compared with the survival of mice of the control groups (p < 0.0001). In addition, adoptive immunization using 300 μl serum and lymphocytes (5*10⁷) of mice immunized with TG290 mRNA-LNP significantly prolonged the survival time of these mice. This study demonstrates that TG290 mRNA-LNP induces specific immune response against T. gondii and may be a potential toxoplasmosis vaccine candidate for this infection.

Opportunistic etiological agents causing lung infections: emerging need to transform lung-targeted delivery

Lung diseases continue to draw considerable attention from biomedical and public health care agencies. The lung with the largest epithelial surface area is continuously exposed to the external environment during exchanging gas. Therefore, the chances of respiratory disorders and lung infections are overgrowing. This review has covered promising and opportunistic etiologic agents responsible for lung infections. These pathogens infect the lungs either directly or indirectly. However, it is difficult to intervene in lung diseases using available oral or parenteral antimicrobial formulations. Many pieces of research have been done in the last two decades to improve inhalable antimicrobial formulations. However, very few have been approved for human use. This review article discusses the approved inhalable antimicrobial agents (AMAs) and identifies why pulmonary delivery is explored. Additionally, the basic anatomy of the respiratory system linked with barriers to AMA delivery has been discussed here. This review opens several new scopes for researchers to work on pulmonary medicines for specific diseases and bring more respiratory medication to market.

Interferon-Inducible E3 Ligase RNF213 Facilitates Host-Protective Linear and K63-Linked Ubiquitylation of Toxoplasma gondii Parasitophorous Vacuoles

The obligate intracellular protozoan pathogen Toxoplasma gondii infects a wide range of vertebrate hosts and frequently causes zoonotic infections in humans. Whereas infected immunocompetent individuals typically remain asymptomatic, toxoplasmosis in immunocompromised individuals can manifest as a severe, potentially lethal disease, and congenital Toxoplasma infections are associated with adverse pregnancy outcomes. The protective immune response of healthy individuals involves the production of lymphocyte-derived cytokines such as interferon gamma (IFN-γ), which elicits cell-autonomous immunity in host cells. IFN-γ-inducible antiparasitic defense programs comprise nutritional immunity, the production of noxious gases, and the ubiquitylation of the Toxoplasma-containing parasitophorous vacuole (PV). PV ubiquitylation prompts the recruitment of host defense proteins to the PV and the consequential execution of antimicrobial effector programs, which reduce parasitic burden. However, the ubiquitin E3 ligase orchestrating these events has remained unknown. Here, we demonstrate that the IFN-γ-inducible E3 ligase RNF213 translocates to Toxoplasma PVs and facilitates PV ubiquitylation in human cells. Toxoplasma PVs become decorated with linear and K63-linked ubiquitin and recruit ubiquitin adaptor proteins in a process that is RNF213 dependent but independent of the linear ubiquitin chain assembly complex (LUBAC). IFN-γ priming fails to restrict Toxoplasma growth in cells lacking RNF213 expression, thus identifying RNF213 as a potent executioner of ubiquitylation-driven antiparasitic host defense. IMPORTANCE Globally, approximately one out of three people become infected with the obligate intracellular parasite Toxoplasma. These infections are typically asymptomatic but can cause severe disease and mortality in immunocompromised individuals. Infections can also be passed on from mother to fetus during pregnancy, potentially causing miscarriage or stillbirth. Therefore, toxoplasmosis constitutes a substantial public health burden. A better understanding of mechanisms by which healthy individuals control Toxoplasma infections could provide roadmaps toward novel therapies for vulnerable groups. Our work reveals a fundamental mechanism controlling intracellular Toxoplasma infections. Cytokines produced during Toxoplasma infections instruct human cells to produce the enzyme RNF213. We find that RNF213 labels intracellular vacuoles containing Toxoplasma with the small protein ubiquitin, which functions as an "eat-me" signal, attracting antimicrobial defense programs to fight off infection. Our work therefore identified a novel antiparasitic protein orchestrating a central aspect of the human immune response to Toxoplasma.

Understanding etiology of community-acquired central nervous system infections using metagenomic next-generation sequencing

Background

Community-acquired central nervous system infections (CA-CNS infections) have the characteristics of acute onset and rapid progression, and are associated with high levels of morbidity and mortality worldwide. However, there have been only limited studies on the etiology of this infections. Here, metagenomic next-generation sequencing (mNGS), a comprehensive diagnosis method, facilitated us to better understand the etiology of CA-CNS infections.

Methods

We conducted a single-center retrospective study between September 2018 and July 2021 in which 606 cerebrospinal fluid (CSF) samples were collected from suspected CNS infectious patients for mNGS testing, and all positive samples were included in this analysis

Results

After the exclusion criteria, a total of 131 mNGS-positive samples were finally enrolled. Bacterial, viral, fungal, parasitic, specific pathogen and mixed infections were accounted for 32.82% (43/131), 13.74% (18/131), 0.76% (1/131), 2.29% (3/131) and 6.87% (9/131), respectively. A total of 41 different pathogens were identified, including 16 bacteria, 12 viruses, 10 fungi, and 1 parasite and 3 specific pathogens. The most frequent infecting pathogens are Epstein-Barr virus (n = 14), Herpes simplex virus 1 (n = 14), Mycobacterium tuberculosis (n = 13), Streptococcus pneumoniae (n = 13), and Cryptococcus neoformans (n = 8). Some difficult-to-diagnose pathogen infections were also detected by mNGS, such as Streptococcus suis, Pseudorabies virus, Bunyavirus, Orientia tsutsugamushi and Toxoplasma gondii.

Conclusion

In this study, mNGS identified a wide variety of pathogens of CA-CNS infections and many of which could not be detected by conventional methods. Our data provide a better understanding of the etiology of CA-CNS infections and show that mNGS represents a comparative screening of CSF in an unbiased manner for a broad range of human pathogens.

Molecular basis of Toxoplasma gondii oryzalin resistance from a novel α-tubulin binding site model

Oryzalin (ORY) is a dinitroaniline derivative that inhibits the microtubule polymerization in plants and parasitic protozoa by selectively binding to the α-tubulin subunit. This herbicidal agent exhibits good antiprotozoal activity against major human parasites, such as Toxoplasma gondii (toxoplasmosis), Leishmania mexicana (leishmaniasis), and Plasmodium falciparum (malaria). Previous chemical mutagenesis assays on T. gondii α-tubulin (TgAT) have identified key mutations that lead to ORY resistance. Herein, we employed alchemical free energy methods and molecular dynamics simulations to determine if the ORY resistance mutations either decrease the TgAT's affinity of the compound or increase the protein stability. Our results here suggest that L136F and V202F mutations significantly decrease the affinity of ORY to TgAT, while T239I and V252L mutations diminish TgAT's flexibility. On the other hand, protein stability predictors determined that R243S mutation reduces TgAT stability due to the loss of its salt bridge interaction with E27. Interestingly, molecular dynamics simulations confirm that the loss of this key interaction leads to ORY binding site closure. Our study provides a better insight into the TgAT-ORY interaction, further supporting our recently proposed ORY-binding site.

Uba1: A Potential Ubiquitin-like Activator Protein of Urm1 in Toxoplasma gondii

We had shown in our previous study that TgUrm1 (ubiquitin-related Modifier 1) was involved in the regulation of anti-oxidant stress in Toxoplasma gondii by conjugating with TgAhp1. It is generally believed that Urm1 binds to target proteins through a mechanism involving Uba (ubiquitin-like activator protein). Here, we identified the TgUrm1-exclusive ubiquitin-like activator-TgUba1, which was located in the cytoplasm of Toxoplasma. TgUba1 contained three domains, including the atrophin-1 domain (ANT1), the E1-like domain (AD), and the rhodanese homology domain (RHD). We explored the interaction of TgUba1 with TgUrm1, and the AD domain was essential for the interaction of the two proteins. The TgUba1 knockout and complementary mutants were obtained based on CRISPR/Cas9 gene editing technology. The knockout of TgUba1 attenuated parasite proliferation and virulence in mice, but not invasion and egress processes, revealing the pivotal role played by TgUba1 in T. gondii survival. Meanwhile, the conjugate band of TgUrm1 was significantly reduced under oxidative stress stimulation without TgUba1, indicating that TgUba1 enhanced the targeted conjugation ability of TgUrm1 in response to oxidative stress, especially under diamide (Dia) stimulation. Furthermore, eleven TgUba1-interacting proteins were identified by proximity-based protein labeling techniques, relating them to ubiquitin-like modifications, anti-oxidative stress and metabolic regulation processes. In conclusion, TgUba1 was essential for T. gondii survival and might be a potential ubiquitin-like activator protein for TgUrm1.

Protective effect of ginsenoside Rh2 against Toxoplasma gondii infection-induced neuronal injury through binding TgCDPK1 and NLRP3 to inhibit microglial NLRP3 inflammasome signaling pathway

BACKGROUND

Toxoplasma gondii (T. gondii) is a neurotropic obligate intracellular parasite that can activate microglial and promote neuronal apoptosis, leading to central nervous system diseases. The NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome signaling complex plays a key role in inducing neuroinflammation. Our previous studies have found that ginsenoside Rh2 (GRh2) inhibits T. gondii infection-induced microglial activation and neuroinflammation by downregulating the Toll-like receptor 4/nuclear factor-kappa B signaling pathway. However, whether GRh2 reduces T. gondii infection-induced neuronal injury through actions on microglial NLRP3 inflammasome signaling has not yet been clarified.

METHODS

In this study, we employed T. gondii RH strain to establish in vitro and in vivo infection models in BV2 microglia cell line and BALB/c mice. Molecular docking, localized surface plasmon resonance assay, quantitative competitive-PCR, ELISA, western blotting, flow cytometric analysis, and immunofluorescence were performed.

RESULTS

Our results showed that GRh2 alleviated neuropathological damage and neuronal apoptosis in cortical tissue of T. gondii-infected mice. GRh2 and CY-09 (an inhibitor of NLRP3) exhibited potent anti-T. gondii effects through binding T. gondii calcium-dependent protein kinase 1 (TgCDPK1). GRh2 decreased Iba-1 (a specific microglial marker) and NLRP3 inflammasome signaling pathway-related protein expression by binding NLRP3. Co-culture of microglia/primary cortical neurons revealed that T. gondii-induced microglial activation caused neuronal apoptosis, but GRh2 reduced this effect, consistent with the effects of CY-09.

CONCLUSION

Taken together, our results show that GRh2 has a protective effect against T. gondii infection-induced neuronal injury by binding TgCDPK1 and NLRP3 to inhibit NLRP3 inflammasome signaling pathway in microglia.

Anti-Tumor Effect of Parasitic Protozoans

The immune system may aberrantly silence when against “altered self”, which consequently may develop into malignancies. With the development of tumor immunology and molecular biology, the deepened understanding of the relationship between parasites and tumors shifts the attitude towards parasitic pathogens from elimination to utilization. In recent years, the antitumor impact implemented by protozoan parasites and the derived products has been confirmed. The immune system is activated and enhanced by some protozoan parasites, thereby inhibiting tumor growth, angiogenesis, and metastasis in many animal models. In this work, we reviewed the available information on the antitumor effect of parasitic infection or induced by parasitic antigen, as well as the involved immune mechanisms that modulate cancer progression. Despite the fact that clinical trials of the protozoan parasites against tumors are limited and the specific mechanisms of the effect on tumors are not totally clear, the use of genetically modified protozoan parasites and derived molecules combined with chemotherapy could be an important element for promoting antitumor treatment in the future.

The first apicoplast tRNA thiouridylase plays a vital role in the growth of Toxoplasma gondii

Toxoplasmosis caused by the protozoan Toxoplasma gondii is one of the most common parasitic diseases in humans and almost all warm-blooded animals. Lys, Glu, and Gln-specific tRNAs contain a super-modified 2-thiourea (s²U) derivatives at the position 34, which is essential for all living organisms by maintaining the structural stability and aminoacylation of tRNA, and the precision and efficiency of codon recognition during protein translation. However, the enzyme(s) involved in this modification in T. gondii remains elusive. In this report, three putative tRNA-specific 2-thiolation enzymes were identified, of which two were involved in the s²U34 modification of tRNA^Lys, tRNA^Glu, and tRNA^Gln. One was named TgMnmA, an apicoplast-located tRNA-specific 2-thiolation enzyme in T. gondii. Knockout of TgMnmA showed that this enzyme is important for the lytic cycle of tachyzoites. Loss of TgMnmA also led to abnormities in apicoplast biogenesis and severely disturbed apicoplast genomic transcription. Notably, mice survived from the infection with 10 TgMnmA-KO RH tachyzoites. These findings provide new insights into s²U34 tRNA modification in Apicomplexa, and suggest TgMnmA, the first apicoplast tRNA thiouridylase identified in all apicomplexans, as a potential drug target.

Drug Repurposing Based on Protozoan Proteome: In Vitro Evaluation of In Silico Screened Compounds against Toxoplasma gondii

Toxoplasma gondii is a protozoan that infects up to a third of the world's population. This parasite can cause serious problems, especially if a woman is infected during pregnancy, when toxoplasmosis can cause miscarriage, or serious complications to the baby, or in an immunocompromised person, when the infection can possibly affect the patient's eyes or brain. To identify potential drug candidates that could counter toxoplasmosis, we selected 13 compounds which were pre-screened in silico based on the proteome of T. gondii to be evaluated in vitro against the parasite in a cell-based assay. Among the selected compounds, three demonstrated in vitro anti-T. gondii activity in the nanomolar range (almitrine, bortezomib, and fludarabine), and ten compounds demonstrated anti-T. gondii activity in the micromolar range (digitoxin, digoxin, doxorubicin, fusidic acid, levofloxacin, lomefloxacin, mycophenolic acid, ribavirin, trimethoprim, and valproic acid). Almitrine demonstrated a Selectivity Index (provided by the ratio between the Half Cytotoxic Concentration against human foreskin fibroblasts and the Half Effective Concentration against T. gondii tachyzoites) that was higher than 47, whilst being considered a lead compound against T. gondii. Almitrine showed interactions with the Na+/K+ ATPase transporter for Homo sapiens and Mus musculus, indicating a possible mechanism of action of this compound.

Epidemiology of Toxoplasmosis among the Pakistani Population: A Systematic Review and Meta-Analysis

Toxoplasma gondii is an intracellular obligate parasite that causes toxoplasmosis, a zoonotic infection that affects warm-blooded animals and humans worldwide. To comprehensively characterize the disease condition in Pakistan for future reference, we ascertained the prevalence of Toxoplasma infection and predisposing factors in the Pakistani population over a 20-year period. We systematically reviewed research articles published in English (2000−2020) from PubMed and Google Scholar. The search results 26 publications involving 10,924 people and 2611 seropositive cases. The toxoplasmosis seropositivity rate was higher in women (25.44%) as compared to men (21.48%) and were statistically significant (p < 0.001). Furthermore, seropositivity was high among people with direct contact with cats, who consumed uncooked meat and raw vegetables, had poor education, and lived in rural areas. The 35−65-year age group had the highest prevalence rate of T. gondii infection. Toxoplasma infection was significantly more prevalent in Khyber Pakhtunkhwa province (25.87%) than in Punjab (20.42%) (p < 0.001). This is the first comprehensive analysis of T. gondii infection epidemiology in Pakistan. It reveals a high frequency of infection among women. We strongly encourage further research to aid patient care and the development of more efficient diagnostic tests and preventative techniques.

Systematic identification of the lysine lactylation in the protozoan parasite Toxoplasma gondii

Background

Lysine lactylation (Kla) is a novelposttranslational modification (PTM) identified in histone and nonhistone proteins of several eukaryotic cells that directly activates gene expression and DNA replication. However, very little is known about the scope and cellular distribution of Kla in apicomplexan parasites despite its significance in public and animal health care.

Methods

Toxoplasma gondii, the causative agent of toxoplasmosis, is an obligate intracellular apicomplexan parasite that can infect different nucleated cell types of animals and humans. We used this parasite as a model organism and extracted the total protein of tachyzoites to produce the first global lysine lactylome profile of T. gondii through liquid chromatography–tandem mass spectrometry. We also investigated the level and localization of the Kla protein in T. gondii using western blotting and the indirect fluorescent antibody test (IFA), respectively.

Results

A total of 983 Kla sites occurring on 523 lactylated proteins were identified in the total protein extracted from Toxoplasma tachyzoites, the acute toxoplasmosis-causing stage. Bioinformatics analysis revealed that the lactylated proteins were evolutionarily conserved and involved in a wide variety of cellular functions, such as energy metabolism, gene regulation and protein biosynthesis. Subcellular localization analysis and IFA results further revealed that most of the lactylated T. gondii proteins were localized in the nucleus, indicating the potential impact of Kla on gene regulation in the T. gondii model. Notably, an extensive batch of parasite-specific proteins unique to phylum Apicomplexa is lactylated in T. gondii.

Conclusions

This study revealed that Kla is widespread in early dividing eukaryotic cells. Lactylated proteins, including a batch of unique parasite proteins, are involved in a remarkably diverse array of cellular functions. These valuable data will improve our understanding of the evolution of Kla and potentially provide the basis for developing novel therapeutic avenues.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05315-6.

Toxoplasma gondii causes changes in the host's expression of cancer‑associated miRNAs

Throughout the world, numerous individuals are infected with Toxoplasma gondii, which may improve immunity against cancer. Furthermore, microRNAs (miRs) may be differentially expressed in the host upon infection with T. gondii. In the present study, RNA-sequencing analysis and reverse transcription-quantitative PCR revealed that miR-429-3p, miR-145a-5p, miR-211-5p, miR-31-3p and miR-135a-5p were determined to be downregulated, while miR-21a-3p, miR-135b-5p, miR-210-5p and miR-146-3p were upregulated in mice post-infection with T. gondii. Antitumor genes [TNF receptor superfamily member 11b, large tumor suppressor kinase (Lats)2 and Lats1] were identified as targets of miR-429-3p, miR-145a-5p, miR-211-5p, miR-31-3p and miR-135a-5p with a luciferase reporter assay. In addition, the protein levels of Lats2 and Lats1 were detected to be higher in T. gondii-infected mice than in the control group. Therefore, these results provide favorable evidence for the suppression of cancer upon T. gondii infection and may give novel ideas for the treatment of tumors.

Toxoplasma TgAtg8-TgAtg3 Interaction Primarily Contributes to Apicoplast Inheritance and Parasite Growth in Tachyzoite

The apicoplast, which harbors key pathways involved in biosynthesis of vital metabolites, is a unique and essential nonphotosynthetic plastid organelle in apicomplexan parasites. Intriguingly, autophagy-related protein 8 (Atg8), a highly conserved eukaryotic protein, can localize to the outermost membrane of the apicoplast and modulate its inheritance in both Toxoplasma and Plasmodium parasites. The Atg8-Atg3 interaction plays a key role in Atg8 lipidation and localization, and our previously work in Toxoplasma has suggested that the core Atg8-family interacting motif (AIM) in TgAtg3, ²³⁹FADI²⁴², and the R27 residue of TgAtg8 contribute to TgAtg8-TgAtg3 interaction in vitro. However, little is known about the function of this interaction or its importance in tachyzoite growth in Toxoplasma gondii. Here, we generated two complemented cell lines, TgAtg3^F239A/I242A and TgAtg8^R27E, based on the TgAtg3 and TgAtg8 conditional knockdown cell lines, respectively. We found that both mutant complemented cell lines were severely affected in terms of tachyzoite growth and displayed delayed death upon conditional knockdown of endogenous TgAtg3 or TgAtg8. Intriguingly, both complemented lines appeared to be defective in TgAtg8 lipidation and apicoplast inheritance. Moreover, we showed that the interaction of TgAtg8 and TgAtg3 is critical for TgAtg8 apicoplast localization. In addition, we found that the TgAtg3^F239A/I242A complemented line exhibits an integral mitochondrial network upon ablation of endogenous TgAtg3, which is distinct from TgAtg3-depleted parasites with a fragmented mitochondrial network. Taken together, this work solidifies the contribution of the TgAtg8-TgAtg3 interaction to apicoplast inheritance and the growth of T. gondii tachyzoites.

IMPORTANCEToxoplasma gondiiis a widespread intracellular parasite infecting a variety of warm-blooded animals, including humans. Current frontline treatment of toxoplasmosis suffers many drawbacks, including toxicity, drug resistance, and failure to eradicate tissue cysts, underscoring the need to identify novel drug targets for suppression or treatment of toxoplasmosis. TgAtg8 is thought to serve multiple functions in lipidation and is considered essential to the growth and development of both tachyzoites and bradyzoites. Here, we show that Toxoplasma gondii has adapted a conserved Atg8-Atg3 interaction, required for canonical autophagy in other eukaryotes, to function specifically in apicoplast inheritance. Our finding not only highlights the importance of TgAtg8-TgAtg3 interaction in tachyzoite growth but also suggests that this interaction is a promising drug target for the therapy of toxoplasmosis.

Comparative Phosphoproteomic Analysis of Sporulated Oocysts and Tachyzoites of Toxoplasma gondii Reveals Stage-Specific Patterns

Toxoplasma gondii is an obligate intracellular protozoan of severe threat to humans and livestock, whose life history harbors both gamic and apogamic stages. Chinese 1 (ToxoDB#9) was a preponderant genotype epidemic in food-derived animals and humans in China, with a different pathogenesis from the strains from the other nations of the world. Posttranslational modifications (PTMs) of proteins were critical mediators of the biology, developmental transforms, and pathogenesis of protozoan parasites. The phosphoprotein profiling and the difference between the developmental phases of T. gondii, contributing to development and infectivity, remain unknown. A quantitative phosphoproteomic approach using IBT integrated with TiO₂ affinity chromatography was applied to identify and analyze the difference in the phosphoproteomes between the sporulated oocysts and the tachyzoites of the virulent ToxoDB#9 (PYS) strain of T. gondii. A total of 4058 differential phosphopeptides, consisting of 2597 upregulated and 1461 downregulated phosphopeptides, were characterized between sporulated the oocysts and tachyzoites. Twenty-one motifs extracted from the upregulated phosphopeptides contained 19 serine motifs and 2 threonine motifs (GxxTP and TP), whereas 16 motifs identified from downregulated phosphopeptides included 13 serine motifs and 3 threonine motifs (KxxT, RxxT, and TP). Beyond the traditional kinases, some infrequent classes of kinases, including Ab1, EGFR, INSR, Jak, Src and Syk, were found to be corresponding to motifs from the upregulated and downregulated phosphopeptides. Remarkable functional properties of the differentially expressed phosphoproteins were discovered by GO analysis, KEGG pathway analysis, and STRING analysis. S8GFS8 (DNMT1-RFD domain-containing protein) and S8F5G5 (Histone kinase SNF1) were the two most connected peptides in the kinase-associated network. Out of these, phosphorylated modifications in histone kinase SNF1 have functioned in mitosis and interphase of T. gondii, as well as in the regulation of gene expression relevant to differentiation. Our study discovered a remarkable difference in the abundance of phosphopeptides between the sporulated oocysts and tachyzoites of the virulent ToxoDB#9 (PYS) strain of T. gondii, which may provide a new resource for understanding stage-specific differences in PTMs and may enhance the illustration of the regulatory mechanisms contributing to the development and infectivity of T. gondii.

Ginsenoside Rh2 reduces depression in offspring of mice with maternal toxoplasma infection during pregnancy by inhibiting microglial activation via the HMGB1/TLR4/NF-κB signaling pathway

Background

Maternal Toxoplasma gondii (T. gondii) infection during pregnancy has been associated with various mental illnesses in the offspring. Ginsenoside Rh2 (GRh2) is a major bioactive compound obtained from ginseng that has an anti-T. gondii effect and attenuates microglial activation through toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signaling pathway. GRh2 also alleviated tumor-associated or lipopolysaccharide-induced depression. However, the effects and potential mechanisms of GRh2 on depression-like behavior in mouse offspring caused by maternal T. gondii infection during pregnancy have not been investigated.

Methods

We examined GRh2 effects on the depression-like behavior in mouse offspring, caused by maternal T. gondii infection during pregnancy, by measuring depression-like behaviors and assaying parameters at the neuronal and molecular level.

Results

We showed that GRh2 significantly improved behavioral measures: sucrose consumption, forced swim time and tail suspended immobility time of their offspring. These corresponded with increased tissue concentrations of 5-hydroxytryptamine and dopamine, and attenuated indoleamine 2,3-dioxygenase or enhanced tyrosine hydroxylase expression in the prefrontal cortex. GRh2 ameliorated neuronal damage in the prefrontal cortex. Molecular docking results revealed that GRh2 binds strongly to both TLR4 and high mobility group box 1 (HMGB1).

Conclusion

This study demonstrated that GRh2 ameliorated the depression-like behavior in mouse offspring of maternal T. gondii infection during pregnancy by attenuating the excessive activation of microglia and neuroinflammation through the HMGB1/TLR4/NF-κB signaling pathway. It suggests that GRh2 could be considered a potential therapy in preventing and treating psychiatric disorders in the offspring mice of mothers with prenatal exposure to T. gondii infection.

Resveratrol modulates Toxoplasma gondii infection induced liver injury by intervening in the HMGB1/TLR4/NF-κB signaling pathway

Toxoplasma gondii (T. gondii) is an obligate intracellular parasite that can cause liver diseases in the host, including hepatitis and hepatomegaly. High mobility group box 1 (HMGB1) is the main inflammatory mediator causing cell injury or necrosis. HMGB1 binds to toll like receptor 4 (TLR4), then activates the nuclear factor-κB (NF-κB) signaling pathway, which promotes the release of inflammatory factors. Our previous studies showed that HMGB1 mediated TLR4/NF-κB signaling pathway plays an important role in liver injury induced by T. gondii infection. Resveratrol (RSV) is a small polyphenol, which has anti-inflammatory, anti-cancer, anti-T. gondii effect. However, the effect of RSV on liver injury caused by T. gondii infection is unclear. This study used the RH strain tachyzoites of T. gondii to infect murine liver line, NCTC-1469 cells to establish an in vitro model and acute infection of mice for the in vivo model to explore the protective effect of RSV on liver injury induced by T. gondii infection. The results showed that RSV inhibited the proliferation of T. gondii in the liver, reduced the alanine aminotransferase/aspartate aminotransferase levels and pathological liver damage. Additionally, RSV inhibited the production of tumor necrosis factor-α, inducible nitric oxide synthase and HMGB1 by interfering with the TLR4/NF-κB signaling pathway. These results indicate that RSV can protect liver injury caused by T. gondii infection by intervening in the HMGB1/TLR4/NF-κB signaling pathway. This study will provide a theoretical basis for RSV treatment of T. gondii infection induced liver injury.

Monoclonal Antibodies for Protozoan Infections: A Future Reality or a Utopic Idea?

Following the SARS-CoV-2 pandemic, several clinical trials have been approved for the investigation of the possible use of mAbs, supporting the potential of this technology as a therapeutic approach for infectious diseases. The first monoclonal antibody (mAb), Muromonab CD3, was introduced for the prevention of kidney transplant rejection more than 30 years ago; since then more than 100 mAbs have been approved for therapeutic purposes. Nonetheless, only four mAbs are currently employed for infectious diseases: Palivizumab, for the prevention of respiratory syncytial virus (RSV) infections, Raxibacumab and Obiltoxaximab, for the prophylaxis and treatment against anthrax toxin and Bezlotoxumab, for the prevention of Clostridium difficile recurrence. Protozoan infections are often neglected diseases for which effective and safe chemotherapies are generally missing. In this context, drug resistance and drug toxicity are two crucial problems. The recent advances in bioinformatics, parasite genomics, and biochemistry methodologies are contributing to better understand parasite biology, which is essential to guide the development of new therapies. In this review, we present the efforts that are being made in the evaluation of mAbs for the prevention or treatment of leishmaniasis, Chagas disease, malaria, and toxoplasmosis. Particular emphasis will be placed on the potential strengths and weaknesses of biological treatments in the control of these protozoan diseases that are still affecting hundreds of thousands of people worldwide.

New role of sertraline against Toxoplasma gondii-induced depression-like behaviours in mice

Toxoplasma gondii (T. gondii) is a neurotropic protozoan parasite, which can cause mental and behavioural disorders. The present study aimed to elucidate the effects and underlying molecular mechanisms of sertraline (SERT) on T. gondii-induced depression-like behaviours. In the present study, a mouse model and a microglial cell line (BV2 cells) model were established by infecting with the T. gondii RH strain. In in vivo and in vitro experiments, the underlying molecular mechanisms of SERT in inhibiting depression-like behaviours and cellular perturbations caused by T. gondii infection were investigated in the mouse brain and BV2 cells. The administration of SERT significantly ameliorated depression-like behaviours in T. gondii-infected mice. Furthermore, SERT inhibited T. gondii proliferation. Treatment with SERT significantly inhibited the activation of microglia and decreased levels of pro-inflammatory cytokines such as tumour necrosis factor-alpha, and interferon-gamma, by down-regulating tumour necrosis factor receptor 1/nuclear factor-kappa B signalling pathway, thereby ameliorating the depression-like behaviours induced by T. gondii infection. Our study provides insight into the underlying molecular mechanisms of the newly discovered role of SERT against T. gondii-induced depression-like behaviours.