Lipid peroxidation and its repair in malaria parasites

Changes in Lipid Profile Secondary to Asymptomatic Malaria in Migrants from Sub-Saharan Africa: A Retrospective Analysis of a 2010-2022 Cohort

Altered lipid profiles have been observed in acute malaria, though mechanisms remain unclear. The impact of asymptomatic submicroscopic malaria infection (AMI) on lipids is unexploredAn observational, comparative, retrospective study was conducted of 1278 asymptomatic Sub-Saharan African migrants (ASSAMs) screened for malaria and lipid profiles during health exams (2010-2022). A systematic screening protocol for infectious disease was performed, including screening for Plasmodium spp. infection by polymerase chain reaction (PCR).Among 800 ASSAMs screened for malaria, 104 (13%) were PCR-positive: P. falciparum (68.72%), P. malariae (18.27%), P. ovale (9.62%), and mixed infections (3.8%). Participants with AMIs exhibited lower baseline lipid levels: total cholesterol (146 vs. 163 mg/dL; p < 0.001), HDL (43 vs. 47 mg/dL; p < 0.001), and LDL (87.5 vs. 98 mg/dL; p < 0.001), with no differences in triglycerides. After treatment, lipid levels partially equalized: total cholesterol (156 vs. 166; p = 0.01), HDL (44 vs. 47.5; p = 0.05), LDL (102 vs. 108.5; p = 0.31), with no changes in triglycerides. Patients with AMI showed higher rates of co-infections (Strongyloides 20.61% vs. 14.35%; p < 0.001; filariae 7.69% vs. 1.91%; p = 0.02) and lower mean corpuscular volume (87.2 vs. 85; p < 0.001). Conclusions: These findings suggest that cholesterol reductions in AMI are not solely due to acute inflammation but may reflect chronic inflammatory processes triggered by asymptomatic malaria. This supports a potential link between AMI and lipid profile changes, underscoring its role in subclinical chronic inflammation.

Galleria mellonella as a drug discovery model to study oxidative stress

Biological systems are equipped with endogenous antioxidant defence mechanisms against reactive oxygen species (ROS). Accumulation of ROS usually overwhelms this, creating pathologic effects. Oxidative toxicity has been reported as a causative factor in neurodegenerative diseases, cancer and diabetes mellitus (DM). However, developing an elaborate in vivo model system for mechanistic and therapeutic studies has been challenging. This present study sought to establish Galleria mellonella larvae as an ideal model for studying oxidative toxicity as a precursor to in vitro studies. We investigated Indole-3-propionic acid, Trolox, Resveratrol, Alpha tocopherol, Alpha lipoic acid, Orotic acid, Ginsenoside RB1, and Xanthohumol in this study, based on their antioxidant effects previously reported in different disease models. Tolerable concentrations of the compounds were established in vivo. Whilst no toxicity was recorded following treatment with Alpha tocopherol and Orotic acid, the remaining compounds displayed marked toxicity. We then conducted cell viability experiments in primary human fibroblast cell lines, and observed that tolerable concentrations in larvae produced 50-100% cell viability in vitro. Finally, Resveratrol and Alpha tocopherol were observed to rescue the larvae from juglone-induced oxidative toxicity. The larvae of Galleria mellonella can therefore be used for conducting oxidative toxicity and proof-of-concept studies of compounds.

Mendelian randomization study of lipid species reveals causal relationship with syphilis

Although some studies have reported a possible association between lipid and the development and progression of syphilis, the overall causal relationship between lipid and syphilis remains unclear. Data abstracted from extensive genome-wide association studies were utilized to pinpoint genetic variations linked to 179 distinct lipid species. Subsequently, these variations served as instrumental variables in Mendelian Randomization (MR) analyses, aimed at evaluating the causal impact of these lipid species on the occurrence of syphilis. A range of methods, including Weighted Mode, Weighted Median, Simple Mode, MR Egger, and Inverse Variance Weighted, were employed to determine the causal influence. For the purpose of sensitivity analysis, techniques such as Inverse Variance Weighted, MR-Egger, the MR Steiger test, the MR-Egger Intercept Test, and MR-PRESSO were applied. Additionally, Multivariate Mendelian Randomization (MVMR) analyses were conducted to directly assess the causal effect of lipid species on the risk of syphilis. Sterol ester (SE) and phosphatidylcholine (PC) could potentially impact syphilis risk. Specifically, SE (27:1/16:0), SE (27:1/18:2), SE (27:1/18:3), SE (27:1/20:3), and SE (27:1/22:6) were linked to an elevated risk of syphilis. PC (18:2_0:0) was linked to an elevated risk of syphilis. In contrast, PC (16:1_18:0) exhibited a protective role against syphilis. No heterogeneity or horizontal pleiotropy was detected. SE (27:1/16:0), SE (27:1/18:2), SE(27:1/18:3), SE (27:1/20:3), and SE (27:1/22:6) were no longer significantly associated with syphilis in the MVMR analysis (P>0.05). In addition, the previously observed effect of PC (18:2_0:0) on syphilis in univariate MR Was no longer significant in MVMR analysis. However, genetically predicted PC (16:1_18:0) was still significantly negatively associated with syphilis, consistent with univariate MR analysis. We observed that hereditary SE and PC levels appear to be associated with syphilis susceptibility. Future research is needed to understand the mechanisms behind this supposed causation and to develop corresponding treatment strategies.

Molecular identification of a thioredoxin peroxidase in Babesia gibsoni with potential against oxidative stress

Babesia gibsoni is the infectious agent of canine babesiosis, a vector-borne infection that poses a global threat to the canine health. As B. gibsoni is an erythrocytic intracellular parasite, the completion of its genome and transcriptome sequencing and analysis facilitates the elucidation of the mechanism of B. gibsoni residue in the erythrocyte. The main function of red blood cells (RBCs) is oxygen delivery; thus, B. gibsoni may be exposed to high levels of oxidative stress. To date, no report is available on the mechanism by which B. gibsoni survives oxidative stress inside the RBCs. In this study, the thioredoxin peroxidase, an important type of peroxidoxin, was identified from B. gibsoni, with 255 amino acids and a molecular weight of 27.7 kDa. There are two conserved "VCP" domains at the N- and C-termini, respectively, indicating that this gene was a 2-Cys peroxiredoxin belonging to the PTZ00137 superfamily. It was named BgTPx-2 and was detected to be located in the B. gibsoni-infected erythrocytes through an indirect immunofluorescence assay using the polyclonal antibody against the recombinant TPx-2. Additionally, its antioxidant activity was analyzed by mixed-function oxidation assay, and BgTPx-2 could protect the pBluescript SK ( +) plasmid from oxidative damage, suggesting an antioxidant function of BgTPx-2. Moreover, the immunogenicity of BgTPx-2 was tested by Western blotting and ELISA using the serum of beagle dogs infected with B. gibsoni, and the positive serum exhibited a detectable and significant antibody response against BgTPx-2 on day 4 and day 9 post-infection, respectively.

Post-Translational Modifications of Proteins of Malaria Parasites during the Life Cycle

Post-translational modifications (PTMs) are essential for regulating protein functions, influencing various fundamental processes in eukaryotes. These include, but are not limited to, cell signaling, protein trafficking, the epigenetic control of gene expression, and control of the cell cycle, as well as cell proliferation, differentiation, and interactions between cells. In this review, we discuss protein PTMs that play a key role in the malaria parasite biology and its pathogenesis. Phosphorylation, acetylation, methylation, lipidation and lipoxidation, glycosylation, ubiquitination and sumoylation, nitrosylation and glutathionylation, all of which occur in malarial parasites, are reviewed. We provide information regarding the biological significance of these modifications along all phases of the complex life cycle of Plasmodium spp. Importantly, not only the parasite, but also the host and vector protein PTMs are often crucial for parasite growth and development. In addition to metabolic regulations, protein PTMs can result in epitopes that are able to elicit both innate and adaptive immune responses of the host or vector. We discuss some existing and prospective results from antimalarial drug discovery trials that target various PTM-related processes in the parasite or host.

Oxidative Stress in Parasitic Diseases-Reactive Oxygen Species as Mediators of Interactions between the Host and the Parasites

Oxidative stress plays a significant role in the development and course of parasitic infections, both in the attacked host organism and the parasite organism struggling to survive. The host uses large amounts of reactive oxygen species (ROS), mainly superoxide anion (O2•-) and hydrogen peroxide (H2O2), to fight the developing parasitic disease. On the other hand, the parasite develops the most effective defense mechanisms and resistance to the effects of ROS and strives to survive in the host organism it has colonized, using the resources and living environment available for its development and causing the host's weakening. The paper reviews the literature on the role of oxidative stress in parasitic diseases, which are the most critical epidemiological problem worldwide. The most common parasitosis in the world is malaria, with 300-500 million new cases and about 1 million deaths reported annually. In Europe and Poland, the essential problem is intestinal parasites. Due to a parasitic infection, the concentration of antioxidants in the host decreases, and the concentration of products of cellular components oxidation increases. In response to the increased number of reactive oxygen species attacking it, the parasites have developed effective defense mechanisms, including primarily the action of antioxidant enzymes, especially superoxide dismutase and nicotinamide adenine dinucleotide phosphate hydrogen (NADPH)-dependent complexes glutathione and thioredoxin.

Identification and characterization of Prx5 and Prx6 in Chilo suppressalis in response to environmental stress

The antioxidant proteins, peroxiredoxins (Prxs), function to protect insects from reactive oxygen species-induced toxicity. In this study, two Prx genes, CsPrx5, and CsPrx6, were cloned and characterized from the paddy field pest, Chilo suppressalis, containing open reading frames of 570 and 672 bp encoding 189 and 223 amino acid polypeptides, respectively. Then, we investigated the influence of various stresses on their expression levels using quantitative real-time PCR (qRT-PCR). The results showed expression of CsPrx5 and CsPrx6 in all developmental stages, with eggs having the highest level. CsPrx5 and CsPrx6 showed higher expression in the epidermis and fat body, and CsPrx6 also showed higher expression in midgut, fat body, and epidermis. Increasing concentrations of insecticides (chlorantraniliprole and spinetoram) and hydrogen peroxide (H2 O2 ) increased the expression levels of CsPrx5 and CsPrx6. In addition, the expression levels of CsPrx5 and CsPrx6 were almost markedly upregulated in larvae under temperature stress or fed by vetiver. Thus, CsPrx5 and CsPrx6 upregulation might increase the C. suppressalis defense response by reducing the impact of environmental stress, providing a better understanding of the relationship between environmental stresses and insect defense systems.

Micromolar Dihydroartemisinin Concentrations Elicit Lipoperoxidation in Plasmodium falciparum-Infected Erythrocytes

Malaria is still the most important parasitic infectious disease. Numerous substances are known to have antimalarial activity; among them, artemisinin is the most widely used one, and artemisinin-based combination therapy (ACT) is recommended for the treatment of Plasmodium falciparum (P.f.) malaria. Antitumor, immunomodulatory, and other therapeutic applications of artemisinin are under extensive study. Several different mechanisms of action were proposed for dihydroartemisinin (DHA), the active metabolite of artemisinin, such as eliciting oxidative stress in target cells. The goal of this study is to monitor the generation of reactive oxygen species (ROS) and lipid peroxidation product 4-hydroxynonenal (4-HNE) by DHA in P.f.-infected human erythrocytes. Checking ROS and 4-HNE-protein adducts kinetics along the maturation of the parasite, we detected the highest level of 4-HNE in ring forms of P.f. due to DHA treatment. Low micromolar concentrations of DHA quickly induced levels of 4-HNE-adducts which are supposed to be damaging. Mass spectrometry identified the P.f. protein cysteine proteinase falcipain-1 as being heavily modified by 4-HNE, and plausibly, 4-HNE conjugation with vital P.f. proteins might contribute to DHA-elicited parasite death. In conclusion, significant 4-HNE accumulation was detectable after DHA treatment, though, at concentrations well above pharmacologically effective ranges in malaria treatment, but at concentrations described for antitumor activity. Thus, lipid peroxidation with consequent 4-HNE conjugation of functionally relevant proteins might be considered as a uniform mechanism for how DHA potentiates antimalarials' action in ACT and controls the progression of tumors.