Biology subjects

Cunnington, A. J.

Publications and source records attributed to Cunnington, A. J..

4 recordsLinked to original sources

bioRxiv2024

Anemia and tissue hypoxia are major determinants of malarial hypelactatemia

Hyperlactatemia, a key marker of severe malaria, is closely linked to increased mortality, though the exact mechanisms remain unclear. It may result from increased lactate production due to tissue hypoxia or reduced lactate clearance from organ dysfunction. This study used Plasmodium yoelii 17XL (Py17XL) murine model of severe malaria, which closely mimics hyperlactatemia seen in human cases, to investigate the contributions of severe anemia and infection-related organ dysfunction to hyperlactatemia. Non-infectious anemia models were also included for comparison. Anemia was found to elevate lactate in both malaria-infected and non-infectious models, but Py17XL infected mice showed higher lactate levels, indicating that anemia alone doesnt fully explain hyperlactatemia. Evidence of tissue hypoxia, particularly in the liver, kidney, and gut, was seen with hypoxyprobe staining and upregulated hypoxia-inducible factor 1-alpha (HIF-1), suggesting that hypoxia drives increased glycolysis and lactate production. Impaired lactate clearance may also play a role, as infected mice showed signs of liver and kidney dysfunction accompanied by reduced clearance of 13C3-labeled sodium-L-Lactate. Whole blood transfusion combined with artesunate significantly improved lactate clearance compared to artesunate alone, underscoring the importance of addressing anemia in treatment. A link between intestinal damage and hyperlactatemia was suggested by correlations between trefoil factor 3 (TFF3), a marker of gut injury, and lactate levels in human samples. Our findings highlight the multifactorial origin of hyperlactatemia in malaria, driven primarily by anemia and tissue hypoxia, pointing to the need for therapies targeting both aspects to reduce mortality in severe cases.

pathology↗

bioRxiv2024

Histone lactylation: a new epigenetic mark in the malaria parasite Plasmodium

Epigenetic processes play important roles in the biology of the malaria parasite Plasmodium falciparum. Here, we characterised a new epigenetic mark, histone lactylation, recently discovered in humans: it was found in two human malaria parasites, P. falciparum and P. knowlesi, and also in vivo in two rodent malaria models. Histones were lactylated rapidly in response to elevated lactate levels, and rapidly delactylated when lactate levels fell. Thus, this mark is well-placed to act as a metabolic sensor, since severe falciparum malaria characteristically leads to hyperlactataemia. Mass spectrometry showed that lysines on several parasite histones could be lactylated, as well as many non-histone chromatin proteins. Histone lactylation was less abundant and less inducible in P. knowlesi than P. falciparum, suggesting that P. falciparum may have evolved particular epigenetic responses to this characteristic feature of its pathology. Finally, in the rodent model P. yoelii, hyperlactataemia correlated with parasite transcriptomic programmes that suggested metabolic dormancy.

microbiology↗

bioRxiv2023

A novel computational pipeline for var gene expression augments the discovery of changes in the Plasmodium falciparum transcriptome during transition from in vivo to short-term in vitro culture

The pathogenesis of severe Plasmodium falciparum malaria involves cytoadhesive microvascular sequestration of infected erythrocytes, mediated by P. falciparum erythrocyte membrane protein 1 (PfEMP1). PfEMP1 variants are encoded by the highly polymorphic family of var genes, the sequences of which are largely unknown in clinical samples. Previously, we published new approaches for var gene profiling and classification of predicted binding phenotypes in clinical P. falciparum isolates (Wichers et al., 2021), which represented a major technical advance. Building on this, we report here a novel method for var gene assembly and multidimensional quantification from RNA-sequencing that outperforms the earlier approach of Wichers et al., 2021 on both laboratory and clinical isolates across a combination of metrics. Importantly, the tool can interrogate the var transcriptome in context with the rest of the transcriptome and can be applied to enhance our understanding of the role of var genes in malaria pathogenesis. We applied this new method to investigate changes in var gene expression through early transition of parasite isolates to in vitro culture, using paired sets of ex vivo samples from our previous study, cultured for up to three generations. In parallel, changes in non-polymorphic core gene expression were investigated. Modest but unpredictable var gene switching and convergence towards var2csa were observed in culture, along with differential expression of 19% of the core transcriptome between paired ex vivo and generation 1 samples. Our results cast doubt on the validity of the common practice of using short-term cultured parasites to make inferences about in vivo phenotype and behaviour.

bioinformatics↗

bioRxiv2017

Integrated pathogen load and dual transcriptome analysis of systemic host-pathogen interactions in severe malaria

The pathogenesis of severe Plasmodium falciparum malaria is incompletely understood. Since the pathogenic stage of the parasite is restricted to blood, dual RNA-sequencing of host and parasite transcripts in blood can reveal their interactions at a systemic scale. Here we identify human and parasite gene expression associated with severe disease features in Gambian children. Differences in parasite load explained up to 99% of differential expression of human genes but only a third of the differential expression of parasite genes. Co-expression analyses showed a remarkable co-regulation of host and parasite genes controlling translation, and host granulopoiesis genes uniquely co-regulated and differentially expressed in severe malaria. Our results indicate that high parasite load is the proximal stimulus for severe P. falciparum malaria, that there is an unappreciated role for many parasite genes in determining virulence, and hint at a molecular arms-race between host and parasite to synthesise protein products.

systems biology↗