bims-toxgon 2023-04-30 papers

bims-toxgon

Biomed News

on Toxoplasma gondii metabolism

Issue of 2023–04–30
nine papers selected by
Lakesh Kumar, BITS Pilani

Toxoplasma gondii HOOK-FTS-HIP Complex is Critical for Secretory Organelle Discharge during Motility, Invasion, and Egress.
The antioxidant protein glutaredoxin 1 is essential for oxidative stress response and pathogenicity of Toxoplasma gondii.
Prenyl Transferases Regulate Secretory Protein Sorting and Parasite Morphology in Toxoplasma gondii.
Metagenomic insights into the composition and function of the gut microbiota of mice infected with Toxoplasma gondii.
Serotyping, a challenging approach for Toxoplasma gondii typing.
In Vitro Evaluation Reveals Effect and Mechanism of Artemether against Toxoplasma gondii.
Changes in K+ Concentration as a Signaling Mechanism in the Apicomplexa Parasites Plasmodium and Toxoplasma.
Protective mucosal and systemic immunity induced by virus-like particles expressing Toxoplasma gondii cyst wall protein.
Novel therapeutic opportunities for Toxoplasma gondii, Trichomonas vaginalis and Giardia intestinalis infections.

mBio. 2023 Apr 24. e0045823

Toxoplasma gondii HOOK-FTS-HIP Complex is Critical for Secretory Organelle Discharge during Motility, Invasion, and Egress.

David J Dubois, Sylia Chehade, Jean-Baptiste Marq, Kannan Venugopal, Bohumil Maco, Albert Tell I Puig, Dominique Soldati-Favre, Sabrina Marion.

  Members of the Apicomplexa phylum possess specialized secretory organelles that discharge, apically and in a timely regulated manner, key factors implicated in parasite motility, host cell invasion, egress and subversion of host cellular functions. The mechanisms regulating trafficking and apical docking of these secretory organelles are only partially elucidated. Here, we characterized two conserved endosomal trafficking regulators known to promote vesicle transport and/or fusion, HOOK and Fused Toes (FTS), in the context of organelle discharge in Toxoplasma gondii. TgHOOK and TgFTS form a complex with a coccidian-specific partner, named HOOK interacting partner (HIP). TgHOOK displays an apically enriched vesicular pattern and concentrates at the parasite apical tip where it colocalizes with TgFTS and TgHIP. Functional investigations revealed that TgHOOK is dispensable but fitness conferring. The protein regulates the apical positioning and secretion of micronemes and contributes to egress, motility, host cell attachment, and invasion. Conditional depletion of TgFTS or TgHIP impacted on the same processes but led to more severe phenotypes. This study provides evidence of endosomal trafficking regulators involved in the apical exocytosis of micronemes and possibly as a consequence or directly on the discharge of the rhoptries. IMPORTANCE Toxoplasma gondii affects between 30 and 80% of the human population, poses a life-threatening risk to immunocompromised individuals, and is a cause of abortion and birth defects following congenital transmission. T. gondii belongs to the phylum of Apicomplexa characterized by a set of unique apical secretory organelles called the micronemes and rhoptries. Upon host cell recognition, this obligatory intracellular parasite secretes specific effectors contained in micronemes and rhoptries to promote parasite invasion of host cells and subsequent persistence. Here, we identified novel T. gondii endosomal trafficking regulators and demonstrated that they regulate microneme organelle apical positioning and exocytosis, thereby strongly contributing to host cell invasion and parasite virulence.

Keywords:  Apicomplexa; FTS; Fused Toes; HOOK; Toxoplasma gondii; egress; endosomal transport; exocytosis; invasion; micronemes; motility; traffic

DOI:  https://doi.org/10.1128/mbio.00458-23
FASEB J. 2023 Jun;37(6): e22932

The antioxidant protein glutaredoxin 1 is essential for oxidative stress response and pathogenicity of Toxoplasma gondii.

Ting-Ting Li, Dan-Yu Zhao, Qin-Li Liang, Hany M Elsheikha, Meng Wang, Li-Xiu Sun, Zhi-Wei Zhang, Xiao-Qing Chen, Xing-Quan Zhu, Jin-Lei Wang.

  Glutaredoxins (Grxs) are ubiquitous antioxidant proteins involved in many molecular processes to protect cells against oxidative damage. Here, we study the roles of Grxs in the pathogenicity of Toxoplasma gondii. We show that Grxs are localized in the mitochondria (Grx1), cytoplasm (Grx2), and apicoplast (Grx3, Grx4), while Grx5 had an undetectable level of expression. We generated Δgrx1-5 mutants of T. gondii type I RH and type II Pru strains using CRISPR-Cas9 system. No significant differences in the infectivity were detected between four Δgrx (grx2-grx5) strains and their respective wild-type (WT) strains in vitro or in vivo. Additionally, no differences were detected in the production of reactive oxygen species, total antioxidant capacity, superoxide dismutase activity, and sensitivity to external oxidative stimuli. Interestingly, RHΔgrx1 or PruΔgrx1 exhibited significant differences in all the investigated aspects compared to the other grx2-grx5 mutant and WT strains. Transcriptome analysis suggests that deletion of grx1 altered the expression of genes involved in transport and metabolic pathways, signal transduction, translation, and obsolete oxidation-reduction process. The data support the conclusion that grx1 supports T. gondii resistance to oxidative killing and is essential for the parasite growth in cultured cells and pathogenicity in mice and that the active site CGFS motif was necessary for Grx1 activity.

Keywords:   Toxoplasma gondii ; biological function; glutaredoxins (Grxs); oxidative stress; virulence

DOI:  https://doi.org/10.1096/fj.202201275R
Int J Mol Sci. 2023 Apr 12. pii: 7172. [Epub ahead of print]24(8):

Prenyl Transferases Regulate Secretory Protein Sorting and Parasite Morphology in Toxoplasma gondii.

Qiang-Qiang Wang, Kai He, Muhammad-Tahir Aleem, Shaojun Long.

  Protein prenylation is an important protein modification that is responsible for diverse physiological activities in eukaryotic cells. This modification is generally catalyzed by three types of prenyl transferases, which include farnesyl transferase (FT), geranylgeranyl transferase (GGT-1) and Rab geranylgeranyl transferase (GGT-2). Studies in malaria parasites showed that these parasites contain prenylated proteins, which are proposed to play multiple functions in parasites. However, the prenyl transferases have not been functionally characterized in parasites of subphylum Apicomplexa. Here, we functionally dissected functions of three of the prenyl transferases in the Apicomplexa model organism Toxoplasma gondii (T. gondii) using a plant auxin-inducible degron system. The homologous genes of the beta subunit of FT, GGT-1 and GGT-2 were endogenously tagged with AID at the C-terminus in the TIR1 parental line using a CRISPR-Cas9 approach. Upon depletion of these prenyl transferases, GGT-1 and GGT-2 had a strong defect on parasite replication. Fluorescent assay using diverse protein markers showed that the protein markers ROP5 and GRA7 were diffused in the parasites depleted with GGT-1 and GGT-2, while the mitochondrion was strongly affected in parasites depleted with GGT-1. Importantly, depletion of GGT-2 caused the stronger defect to the sorting of rhoptry protein and the parasite morphology. Furthermore, parasite motility was observed to be affected in parasites depleted with GGT-2. Taken together, this study functionally characterized the prenyl transferases, which contributed to an overall understanding of protein prenylation in T. gondii and potentially in other related parasites.

Keywords:  TgFT; TgGGT-1; TgGGT-2; Toxoplasma gondii; conditional knockdown

DOI:  https://doi.org/10.3390/ijms24087172
Front Immunol. 2023 ;14 1156397

Metagenomic insights into the composition and function of the gut microbiota of mice infected with Toxoplasma gondii.

Jin-Xin Meng, Xin-Yu Wei, Huanping Guo, Yu Chen, Wei Wang, Hong-Li Geng, Xing Yang, Jiang Jiang, Xiao-Xuan Zhang.

   Introduction: Despite Toxoplasma gondii infection leading to dysbiosis and enteritis, the function of gut microbiota in toxoplasmosis has not been explored.
Methods: Here, shotgun metagenomics was employed to characterize the composition and function of mouse microbial community during acute and chronic T. gondii infection, respectively.
Results: The results revealed that the diversity of gut bacteria was decreased immediately after T. gondii infection, and was increased with the duration of infection. In addition, T. gondii infection led to gut microbiota dysbiosis both in acute and chronic infection periods. Therein, several signatures, including depression of Firmicutes to Bacteroidetes ratio and infection-enriched Proteobacteria, were observed in the chronic period, which may contribute to aggravated gut inflammation and disease severity. Functional analysis showed that a large amount of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways and carbohydrate-active enzymes (CAZy) family displayed distinct variation in abundance between infected and healthy mice. The lipopolysaccharide biosynthesis related pathways were activated in the chronic infection period, which might lead to immune system imbalance and involve in intestinal inflammation. Moreover, microbial and functional spectrums were more disordered in chronic than acute infection periods, thus implying gut microbiota was more likely to participate in disease process in the chronically infected mice, even exacerbated immunologic derangement and disease progression.
Discussion: Our data indicate that the gut microbiota plays a potentially important role in protecting mice from T. gondii infection, and contributes to better understand the association between gut microbiota and toxoplasmosis.

Keywords:  Toxoplasma gondii; gut microbiota; intestinal inflammation; metagenomic sequencing; toxoplasmosis

DOI:  https://doi.org/10.3389/fimmu.2023.1156397
Front Med (Lausanne). 2023 ;10 1111509

Serotyping, a challenging approach for Toxoplasma gondii typing.

Susana Sousa, Maria Fernandes, José Manuel Correia da Costa.

  Genotype analysis has revealed a high genetic diversity in strains of Toxoplasma gondii, isolated from a wide range of intermediate hosts and different geographic origins. Diversity is notably striking for parasites from wild hosts in South America, generally referred as non-archetypal genotypes. Those genotypes are implicated in the etiology of severe clinical disease, multivisceral toxoplasmosis, associated with high rate of mortality in immunocompetent individuals. Can we accept specific antibodies produced during T. gondii infection as biomarkers to identify infecting genotypes? Scientific evidence supports a positive response to this question; however, the genetic diversity of T. gondii genotypes organized into 16 haplogroups and collectively defined in 6 major clades, provides a reminder of the complexity and difficulty for the purpose. This review discusses serological approaches to genotyping T. gondii.

Keywords:  Toxoplasma gondii; antibodies; peptides; polymorphism; serotype; strain

DOI:  https://doi.org/10.3389/fmed.2023.1111509
Metabolites. 2023 Mar 27. pii: 476. [Epub ahead of print]13(4):

In Vitro Evaluation Reveals Effect and Mechanism of Artemether against Toxoplasma gondii.

Qiong Xu, Yin-Yan Duan, Ming Pan, Qi-Wang Jin, Jian-Ping Tao, Si-Yang Huang.

  Due to the limited effectiveness of existing drugs for the treatment of toxoplasmosis, there is a dire need for the discovery of new therapeutic options. Artemether is an important drug for malaria and several studies have indicated that it also exhibits anti-T. gondii activity. However, its specific effect and mechanisms are still not clear. To elucidate its specific role and potential mechanism, we first evaluated its cytotoxicity and anti-Toxoplasma effect on human foreskin fibroblast cells, and then analyzed its inhibitory activity during T. gondii invasion and intracellular proliferation. Finally, we examined its effect on mitochondrial membrane potential and reactive oxygen species (ROS) in T. gondii. The CC50 value of artemether was found to be 866.4 μM, and IC50 was 9.035 μM. It exhibited anti-T. gondii activity and inhibited the growth of T. gondii in a dose-dependent manner. We also found that the inhibition occurred primarily in intracellular proliferation, achieved by reducing the mitochondrial membrane integrity of T. gondii and stimulating ROS production. These findings suggest that the mechanism of artemether against T. gondii is related to a change in the mitochondrial membrane and the increase in ROS production, which may provide a theoretical basis for optimizing artemether derivatives and further improving their anti-Toxoplasma efficacy.

Keywords:  Toxoplasma gondii; artemether; in vitro; mechanism; mitochondria

DOI:  https://doi.org/10.3390/metabo13040476
Int J Mol Sci. 2023 Apr 14. pii: 7276. [Epub ahead of print]24(8):

Changes in K+ Concentration as a Signaling Mechanism in the Apicomplexa Parasites Plasmodium and Toxoplasma.

Benedito M Dos Santos, Jude M Przyborski, Célia R S Garcia.

  During their life cycle, apicomplexan parasites pass through different microenvironments and encounter a range of ion concentrations. The discovery that the GPCR-like SR25 in Plasmodium falciparum is activated by a shift in potassium concentration indicates that the parasite can take advantage of its development by sensing different ionic concentrations in the external milieu. This pathway involves the activation of phospholipase C and an increase in cytosolic calcium. In the present report, we summarize the information available in the literature regarding the role of potassium ions during parasite development. A deeper understanding of the mechanisms that allow the parasite to cope with ionic potassium changes contributes to our knowledge about the cell cycle of Plasmodium spp.

Keywords:  GPCR; PfSR25; Plasmodium berghei; Plasmodium falciparum; Toxoplasma gondii; calcium; malaria; potassium

DOI:  https://doi.org/10.3390/ijms24087276
PLoS One. 2023 ;18(4): e0283928

Protective mucosal and systemic immunity induced by virus-like particles expressing Toxoplasma gondii cyst wall protein.

Gi-Deok Eom, Ki-Back Chu, Hae-Ji Kang, Min-Ju Kim, Keon-Woong Yoon, Jie Mao, Su-Hwa Lee, Md Atique Ahmed, Eun-Kyung Moon, Fu-Shi Quan.

Toxoplasma gondii host cellular invasion factors such as the rhoptry proteins, micronemal antigens, or other subcellular compartment proteins have shown limited vaccine efficacies. T. gondii cyst wall protein (CST1) as a cyst persistence factor is critical for cyst wall integrity and bradyzoite persistence. Here, we generated influenza virus-like particles (VLPs) expressing the T. gondii CST1 and evaluated the mucosal as well as systemic immunities induced by VLPs. Intranasal immunization with the VLPs induced parasite-specific IgG and IgA antibody responses in sera and intestines. VLP immunization showed higher levels of germinal center B cell response and antibody-secreting cell (ASC) response upon challenge infection, indicating memory B cell response was induced. VLP-immunized mice showed a significant reduction of cyst counts and lower levels of pro-inflammatory cytokines (IFN-γ, IL-6) production in the brain upon T. gondii ME49 challenge infection compared to unimmunized control. Thus, VLP immunization protected mice from the lethal dose challenge infection with T. gondii ME49 and did not incur bodyweight loss. These results indicated that T. gondii CST1 containing VLPs can induce mucosal and systemic immunity and also suggest its developmental potential as an effective vaccine candidate against T. gondii infection.

DOI: https://doi.org/10.1371/journal.pone.0283928
Expert Opin Ther Pat. 2023 Apr 26.

Novel therapeutic opportunities for Toxoplasma gondii, Trichomonas vaginalis and Giardia intestinalis infections.

Francesca Arrighi, Arianna Granese, Paola Chimenti, Paolo Guglielmi.

   INTRODUCTION: Toxoplasma gondii, Trichomonas vaginalis and Giardia intestinalis are the causative agents of Toxoplasmosis, Trichomoniasis and Giardiasis, three important infections threatening human health and affecting millions of people worldwide. Although drugs and treatment are available to fight these protozoan parasites, side-effects and increasing drug resistance, require continuous efforts for the development of novel effective drugs.
AREAS COVERED: The patents search was carried out in September/October 2022 with four official scientific databases (Espacenet, Scifinder, Reaxys, Google Patents). Treatments for Toxoplasmosis, Trichomoniasis and Giardiasis (2015-2022) have been grouped according to their chemotypes. In particular, novel chemical entities have been reported and investigated for their structure-activity relationship, when accessible. On the other hand, drug repurposing, extensively exploited to obtain novel anti-protozoal treatment, has been in-depth described. Finally, natural metabolites and extracts have also been reported.
EXPERT OPINION: T. gondii, T. vaginalis and G. intestinalis are protozoan infections usually controlled by immune system in immunocompetent patients; however, they could represent a threatening health for immunocompromised people. The needs of novel effective drugs, endowed with new mechanisms of actions arises from the increasing drug resistance affecting antibiotic as well as antiprotozoal therapies. In this review different therapeutic approaches to treat protozoan infections have been reported.

Keywords:  Giardia intestinalis; Toxoplasma gondii; Trichomonas vaginalis; natural compounds; natural extracts; newly synthesised anti-protozoal drugs; repurposed drugs

DOI:  https://doi.org/10.1080/13543776.2023.2206017