Modulation of autophagy as a therapeutic strategy for Toxoplasma gondii infection

Cheng, Antony S.; Zhang, Huanan; Chen, Baike; Zheng, Shengyao; Wang, Hongyi; Shi, Yijia; You, Siyao; Li, Ming; Jiang, Liping

doi:10.3389/fcimb.2022.902428

Cited by 9 publications

(12 citation statements)

References 107 publications

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“…This fact may explain the lack of expression in LC3 transcription in THP-1 cell line infected by T. gondii RH strain. Our findings represented that T. gondii in THP-1 cell downregulated transcription of atg 12, while significant phosphorylation of rpS6 in protein level, in the line of previous studies, proposes deregulation of autophagy via mTORC manipulation by T. gondii [ 61 , 62 ]. However, our finding suggests that although immunosuppressant medications prescribed in IBD condition can increase the risk of opportunistic infection and likely re-activation of latent toxoplasmosis, T. gondii tachyzoites are not able to phosphorylate mTORC and inhibit autophagy during AZA treatment in IBD patients.…”

Section: Discussionsupporting

confidence: 92%

Evaluation of the mTORC activity in the presence of Toxoplasma gondii and azathioprine in human monocyte cell line

et al. 2023

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Background Autophagy is an important part of pathogenesis of IBD. Thiopurines such as azathioprine (AZA) are approved drugs for clinical practices in IBD patients. Besides, as an escape strategy, Toxoplasma gondii can use the mTORC1 complex to inactivate autophagy. Methods In this study, we investigated whether T. gondii tachyzoites may modulate autophagy and interfere the effects of azathioprine in IBD treatment. PMA-activated human monocyte cell line (THP-1) was infected with fresh T. gondii RH tachyzoites. After 5 h of infection, the cells were treated with AZA for 6 h. The expression of atg5, atg7, atg12, lc3b, and β-actin (BACT) genes was evaluated using quantitative real-time PCR. To analyze the phosphorylation of ribosomal protein S6 (rpS6), western blot using specific primary antibodies was performed. Results The results of real-time PCR revealed that AZA, T. gondii tachyzoites, and a combination of AZA and T. gondii tachyzoites upregulated atg5 gene for 4.297-fold (P-value = 0.014), 2.49-fold (P-value = 0.006), and 4.76-fold (P-value = 0.001), respectively. The atg7 gene showed significant upregulation (2.272-fold; P-value = 0.014) and (1.51-fold; P-value = 0.020) in AZA and AZA / T. gondii, respectively. The expression of atg12 gene was significantly downregulated in AZA and T. gondii tachyzoites for (8.85-fold; P-value = 0.004) and (2.005-fold; P-value = 0.038), respectively, but upregulated in T. gondii/AZA (1.52-fold; P-value = 0.037). In addition, the lc3b gene was only significantly changed in AZA / T. gondii (3.028-fold; P-value = 0.001). Western blot analysis showed that T. gondii tachyzoites significantly phosphorylated rpS6, and tachyzoites did not interfere the effects of AZA to phosphorylate the rpS6. Conclusion Taken together, although AZA and T. gondii similarly affects the expression levels of atg5, atg7, and atg12, but T. gondii does not seem to modulate the effects of AZA via mTORC functions.

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Section: Discussionsupporting

confidence: 92%

Evaluation of the mTORC activity in the presence of Toxoplasma gondii and azathioprine in human monocyte cell line

et al. 2023

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“…Autophagy is a protective mechanism of eukaryotic cells against stress and infection. Autophagosome and lysosome can digest and degrade abnormal protein aggregation and damaged organelles, which is an adaptive response of most cells in many aspects ( Deretic et al., 2013 ; Cheng et al., 2022 ). In extracellular, T. gondii tachyzoites, autophagosomes are induced in response to amino acid starvation, but they can also be observed during normal intracellular development of the parasite ( Besteiro et al., 2011 ).…”

Section: Introductionmentioning

confidence: 99%

Two small-molecule inhibitors of Toxoplasma gondii proliferation in vitro

Hua

Lin

Xiang

et al. 2023

Front. Cell. Infect. Microbiol.

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BackgroundToxoplasmosis 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.MethodsIn 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.ResultsThe 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.DiscussionTaken 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.

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“…There are four main types of autophagy: autophagosome-mediated macroautophagy, microautophagy, chaperone-mediated autophagy, and non-canonical autophagy ( 9 ). Macroautophagy (hereinafter referred to as autophagy) inhibits T. gondii infection through the formation of a PV-containing autophagosome and its fusion with the lysosome ( 11 ). In addition, the PV can also be targeted via autophagosome-independent processes orchestrated by autophagy proteins in IFN-γ-activated cells ( 12 ).…”

Section: Introductionmentioning

confidence: 99%

“…The host cell autophagic response against T. gondii is mainly triggered by CD40- and IFN-γ-dependent signals that induce the expression and activation of autophagy-related proteins (e.g., ULK1, Beclin-1, and LC3), a process that culminates with the destruction of the parasite by lysosomal enzymes ( 13 , 14 ). Accumulating evidence indicates that activation of the host serine/threonine kinase AKT constitutes one of the strategies developed by T. gondii to avoid autophagy-mediated killing ( 11 , 15 , 16 ). In this regard, it was reported that early and prolonged activation of EGF receptor (EGFR)-dependent AKT phosphorylation by T. gondii was required to prevent accumulation of autophagosome and lysosome components around the PV (i.e., LC3 and LAMP-1, respectively) and reduce parasite replication ( 15 , 16 ).…”

Section: Introductionmentioning

confidence: 99%

Toxoplasma gondii inhibits the expression of autophagy-related genes through AKT-dependent inactivation of the transcription factor FOXO3a

Dı́ez

Leroux

Chagneau

et al. 2023

mBio

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The intracellular parasite Toxoplasma gondii induces host AKT activation to prevent autophagy-mediated clearance; however, the molecular underpinnings are not fully understood. Autophagy can be negatively regulated through AKT-sensitive phosphorylation and nuclear export of the transcription factor Forkhead box O3a (FOXO3a). Using a combination of pharmacological and genetic approaches, herein we investigated whether T. gondii hinders host autophagy through AKT-dependent inactivation of FOXO3a. We found that infection by type I and II strains of T. gondii promotes gradual and sustained AKT-dependent phosphorylation of FOXO3a at residues S253 and T32 in human foreskin fibroblasts (HFF) and murine 3T3 fibroblasts. Mechanistically, AKT-sensitive phosphorylation of FOXO3a by T. gondii required live infection and the activity of PI3K but was independent of the plasma membrane receptor EGFR and the kinase PKCα. Phosphorylation of FOXO3a at AKT-sensitive residues was paralleled by its nuclear exclusion in T. gondii -infected HFF. Importantly, the parasite was unable to drive cytoplasmic localization of FOXO3a upon pharmacological blockade of AKT or overexpression of an AKT-insensitive mutant form of FOXO3a. Transcription of a subset of bona fide autophagy-related targets of FOXO3a was reduced during T. gondii infection in an AKT-dependent fashion. However, parasite-directed repression of autophagy-related genes was AKT-resistant in cells deficient in FOXO3a. Consistent with this, T. gondii failed to inhibit the recruitment of acidic organelles and LC3, an autophagy marker, to the parasitophorous vacuole upon chemically or genetically induced nuclear retention of FOXO3a. In all, we provide evidence that T. gondii suppresses FOXO3a-regulated transcriptional programs to prevent autophagy-mediated killing. IMPORTANCE The parasite Toxoplasma gondii is the etiological agent of toxoplasmosis, an opportunistic infection commonly transmitted by ingestion of contaminated food or water. To date, no effective vaccines in humans have been developed and no promising drugs are available to treat chronic infection or prevent congenital infection. T. gondii targets numerous host cell processes to establish a favorable replicative niche. Of note, T. gondii activates the host AKT signaling pathway to prevent autophagy-mediated killing. Herein, we report that T. gondii inhibits FOXO3a, a transcription factor that regulates the expression of autophagy-related genes, through AKT-dependent phosphorylation. The parasite’s ability to block the recruitment of the autophagy machinery to the parasitophorous vacuole is impeded upon pharmacological inhibition of AKT or overexpression of an AKT-insensitive form of FOXO3a. Thus, our study provides greater granularity in the role of FOXO3a during infection and reinforces the potential of targeting autophagy as a therapeutic strategy against T. gondii .

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Modulation of autophagy as a therapeutic strategy for Toxoplasma gondii infection

Cited by 9 publications

References 107 publications

Evaluation of the mTORC activity in the presence of Toxoplasma gondii and azathioprine in human monocyte cell line

Evaluation of the mTORC activity in the presence of Toxoplasma gondii and azathioprine in human monocyte cell line

Two small-molecule inhibitors of Toxoplasma gondii proliferation in vitro

Toxoplasma gondii inhibits the expression of autophagy-related genes through AKT-dependent inactivation of the transcription factor FOXO3a

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