Macrophage biology and their activation by protozoan-derived glycosylphosphatidylinositol anchors and hemozoin

Phosphatidylinositol synthesis, its selective salvage, and inter-regulation of anionic phospholipids in Toxoplasma gondii

Phosphatidylinositol (PtdIns) serves as an integral component of eukaryotic membranes; however, its biosynthesis in apicomplexan parasites remains poorly understood. Here we show that Toxoplasma gondii-a common intracellular pathogen of humans and animals-can import and co-utilize myo-inositol with the endogenous CDP-diacylglycerol to synthesize PtdIns. Equally, the parasite harbors a functional PtdIns synthase (PIS) containing a catalytically-vital CDP-diacylglycerol phosphotransferase motif in the Golgi apparatus. Auxin-induced depletion of PIS abrogated the lytic cycle of T. gondii in human cells due to defects in cell division, gliding motility, invasion, and egress. Isotope labeling of the PIS mutant in conjunction with lipidomics demonstrated de novo synthesis of specific PtdIns species, while revealing the salvage of other lipid species from the host cell. Not least, the mutant showed decline in phosphatidylthreonine, and elevation of selected phosphatidylserine and phosphatidylglycerol species, indicating a rerouting of CDP-diacylglycerol and homeostatic inter-regulation of anionic phospholipids upon knockdown of PIS. In conclusion, strategic allocation of own and host-derived PtdIns species to gratify its metabolic demand features as a notable adaptive trait of T. gondii. Conceivably, the dependence of T. gondii on de novo lipid synthesis and scavenging can be exploited to develop new anti-infectives.

Is diabetes associated with malaria and malaria severity? A systematic review of observational studies

Background: We conducted a systematic review to study the association between diabetes and malaria as well as malaria severity. Methods: The search was conducted in Embase, Global Health, MEDLINE, Scopus and Web of Science. Titles and abstracts were screened, full-text studied and information extracted for qualitative synthesis. Risk of bias was assessed with ROBINS-I criteria. The exposure was diabetes and the outcome malaria or malaria severity. Results: Of 1992 results, three studies were included (n=7,226). Two studies found strong associations: people with diabetes had higher odds of malaria (adjusted odds ratio (aOR): 1.46 (95% CI: 1.06-2.03)) and severe malaria (aOR: 2.98 (95% CI: 1.25-7.09)). One study did not find conclusive evidence: aOR for severe malaria was 0.95 (95% CI: 0.71-1.28). Risk of bias was high in all the studies. Conclusions: Although the available evidence on the association between diabetes and malaria is limited, the results may suggest there is a non-trivial positive relationship between these conditions.

Is diabetes associated with malaria and malaria severity? A systematic review of observational studies

Background: We conducted a systematic review to study the association between diabetes as a risk factor for malaria. Methods: The search was conducted in Embase, Global Health, MEDLINE, Scopus and Web of Science. Titles and abstracts were screened, full-text studied and information extracted for qualitative synthesis. Risk of bias was assessed with ROBINS-I criteria. The exposure was diabetes and the outcome malaria or malaria severity. Results: Of 1992 results, three studies were included (n=7,226). Two studies found strong associations: people with diabetes had higher odds of malaria (adjusted odds ratio (aOR): 1.46 (95% CI: 1.06-2.03)) and severe malaria (aOR: 2.98 (95% CI: 1.25-7.09)). One study did not find conclusive evidence: aOR for severe malaria was 0.95 (95% CI: 0.71-1.28). Risk of bias was high in all the studies. Conclusions: Although the available evidence on the association between diabetes and malaria is limited, the results may suggest there is a non-trivial positive relationship between these conditions.

Is diabetes associated with malaria and malaria severity? A systematic review of observational studies

Background: We conducted a systematic review to study the association between diabetes as a risk factor for malaria. Methods: The search was conducted in Embase, Global Health, MEDLINE, Scopus and Web of Science. Titles and abstracts were screened, full-text studied and information extracted for qualitative synthesis. Risk of bias was assessed with ROBINS-I criteria. The exposure was diabetes and the outcome malaria or malaria severity. Results: Of 1992 results, three studies were included (n=7,226). Two studies found strong associations: people with diabetes had higher odds of malaria (adjusted odds ratio (aOR): 1.46 (95% CI: 1.06-2.03)) and severe malaria (aOR: 2.98 (95% CI: 1.25-7.09)). One study did not find conclusive evidence: aOR for severe malaria was 0.95 (95% CI: 0.71-1.28). Risk of bias was high in all the studies. Conclusions: Although the available evidence on the association between diabetes and malaria is limited, the results may suggest there is a non-trivial positive relationship between these conditions.

L-Arginine supplementation in mice enhances NO production in spleen cells and inhibits Plasmodium yoelii transmission in mosquitoes

Background

The life cycle of Plasmodium is complex, requiring invasion of two different hosts, humans and mosquitoes. In humans, initiation of an effective Th1 response during early infection is critical for the control of parasite multiplication. In mosquitoes, inhibition of the development of sexual-stage parasites interrupts the parasite transmission. In this study, we aim to investigate whether dietary supplementation of L-arginine (L-Arg) in mice affects Plasmodium yoelii 17XL (Py17XL) transmission in mosquitoes.

Methods

BALB/c mice were orally administered with 1.5 mg/g L-Arg daily for 7 days and infected with Py17XL. The mRNA levels of inducible nitric oxide synthase (iNOS) and arginase 1 in spleen cells were determined by real-time RT-PCR. The amount of nitric oxide (NO) released by spleen cells in vitro was determined by the Griess method. The effect of L-Arg supplementation on subsequent development of P. yoelii gametocytes was evaluated by an in vitro ookinete culture assay and mosquito feeding assay.

Results

Pretreatment of mice with L-Arg significantly increased the transcript level of iNOS in spleen cells and the amount of NO synthesized. Dietary L-Arg supplementation also significantly reduced the number of zygotes and ookinetes formed during in vitro culture and the number of oocysts formed on mosquito midguts after blood feeding.

Conclusions

L-Arg enhances host immunity against blood-stage parasites as well as suppressing subsequent parasite development in mosquitoes. L-Arg as an inexpensive and safe supplement may be used as a novel adjunct treatment against malarial infection.