Reticulocyte Infection Leads to Altered Behaviour, Drug Sensitivity and Host Cell Remodelling by Plasmodium falciparum

AbstractPlasmodia are host-specific, both at the organism and cellular levels. During asexual development, Plasmodium spp. infect cells of erythroid lineage, with an overall propensity towards reticulocytes. This applies to even Plasmodium (P.) falciparum, the most common causative agent of human malaria, implications of which remain unexplored. Herein, for the first time, we characterize the developmental stages and features of P. falciparum cultured in vitro in young reticulocytes (CD71+) in comparison to standard normocyte (CD71-) cultures. We demonstrate that there are notable differences in the patterns of invasion, development and sensitivity to potent antimalarials (such as artemisinin and dihydroartemisinin) for parasites residing in CD71+ reticulocytes. Through a transcriptomic approach, we report that P. falciparum parasites are able to sense the host cell environment, and calibrate their metabolic and host cell remodelling pathways through differential gene expression. These results form an exciting avenue on which hitherto unexplored interactions between Plasmodium spp and different stages of host red blood cells could be investigated in the broader contexts of drug resistance, host tropism and zoonosis.Author SummaryParasites causing malaria infect red blood cells for development and proliferation during asexual development. This asexual erythrocytic stage determines higher parasite densities and eventual disease manifestation. Although the most virulent species of Plasmodium infecting humans known as Plasmodium falciparum is able to infect red blood cells of all ages, these parasites show a preference for younger blood cells. Of note, the biochemical and biophysical properties of young and adult red blood cells vary significantly. Herein, we undertook a comparative profiling of invasion process, parasite development and drug response of Plasmoddium falciparum in two host cells: young red blood cells (reticulocytes) and mature red blood cells (normocytes). We demonstrate that P. falciparum infects human reticulocytes with higher affinity and demonstrate differential sensitivity to drugs such as artemisinin while they reside within reticulocytes. Furthermore, we show that P. falciparum is able to detect differences in host environment and adapt to it by changing the expression of genes required for host cell remodelling.

Download Full-text

Ultrastructural observations on the in vitro cytoadherence of Plasmodium falciparum infected red blood cells

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100162132 ◽

1990 ◽

Vol 48 (3) ◽

pp. 914-915

Author(s):

D.J.P. Ferguson ◽

A.R. Berendt ◽

J. Tansey ◽

K. Marsh ◽

C.I. Newbold

Keyword(s):

Plasmodium Falciparum ◽

Red Blood Cells ◽

Blood Cells ◽

Umbilical Vein ◽

Cell Types ◽

Amelanotic Melanoma ◽

Cytoplasmic Process ◽

Umbilical Vein Endothelial Cells

In human malaria, the most serious clinical manifestation is cerebral malaria (CM) due to infection with Plasmodium falciparum. The pathology of CM is thought to relate to the fact that red blood cells containing mature forms of the parasite (PRBC) cytoadhere or sequester to post capillary venules of various tissues including the brain. This in vivo phenomenon has been studied in vitro by examining the cytoadherence of PRBCs to various cell types and purified proteins. To date, three Ijiost receptor molecules have been identified; CD36, ICAM-1 and thrombospondin. The specific changes in the PRBC membrane which mediate cytoadherence are less well understood, but they include the sub-membranous deposition of electron-dense material resulting in surface deformations called knobs. Knobs were thought to be essential for cytoadherence, lput recent work has shown that certain knob-negative (K-) lines can cytoadhere. In the present study, we have used electron microscopy to re-examine the interactions between K+ PRBCs and both C32 amelanotic melanoma cells and human umbilical vein endothelial cells (HUVEC).We confirm previous data demonstrating that C32 cells possess numerous microvilli which adhere to the PRBC, mainly via the knobs (Fig. 1). In contrast, the HUVEC were relatively smooth and the PRBCs appeared partially flattened onto the cell surface (Fig. 2). Furthermore, many of the PRBCs exhibited an invagination of the limiting membrane in the attachment zone, often containing a cytoplasmic process from the endothelial cell (Fig. 2).

Download Full-text

In Vitro Assessment of Antiplasmodial Activity and Cytotoxicity of Polyalthia longifolia Leaf Extracts on Plasmodium falciparum Strain NF54

Malaria Research and Treatment ◽

10.1155/2019/6976298 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Bethel Kwansa-Bentum ◽

Kojo Agyeman ◽

Jeffrey Larbi-Akor ◽

Claudia Anyigba ◽

Regina Appiah-Opong

Keyword(s):

Plasmodium Falciparum ◽

Ethyl Acetate ◽

Red Blood Cells ◽

Blood Cells ◽

Radical Scavenging ◽

Antimalarial Drugs ◽

Antiplasmodial Activity ◽

Leaf Extracts ◽

Polyalthia Longifolia

Background. Malaria is one of the most important life-threatening infectious diseases in the tropics. In spite of the effectiveness of artemisinin-based combination therapy, reports on reduced sensitivity of the parasite to artemisinin in Cambodia and Thailand warrants screening for new potential antimalarial drugs for future use. Ghanaian herbalists claim that Polyalthia longifolia has antimalarial activity. Therefore, antiplasmodial activity, cytotoxic effects, and antioxidant and phytochemical properties of P. longifolia leaf extract were investigated in this study. Methodology/Principal Findings. Aqueous, 70% hydroethanolic and ethyl acetate leaf extracts were prepared using standard procedures. Antiplasmodial activity was assessed in vitro by using chloroquine-sensitive malaria parasite strain NF54. The SYBR® Green and tetrazolium-based calorimetric assays were used to measure parasite growth inhibition and cytotoxicity, respectively, after extract treatment. Total antioxidant activity was evaluated using a free radical scavenging assay. Results obtained showed that extracts protected red blood cells against Plasmodium falciparum mediated damage. Fifty percent inhibitory concentration (IC50) values were 24.0±1.08 μg/ml, 22.5±0.12 μg/ml, and 9.5±0.69 μg/ml for aqueous, hydroethanolic, and ethyl acetate extracts, respectively. Flavonoids, tannins, and saponins were present in the hydroethanolic extract, whereas only the latter was observed in the aqueous extract. Aqueous and hydroethanolic extracts showed stronger antioxidant activities compared to the ethyl acetate extract. Conclusions/Significance. The extracts of P. longifolia have antiplasmodial properties and low toxicities to human red blood cells. The extracts could be developed as useful alternatives to antimalarial drugs. These results support claims of the herbalists that decoctions of P. longifolia are useful antimalarial agents.

Download Full-text

Conserved regions from Plasmodium falciparum MSP11 specifically interact with host cells and have a potential role during merozoite invasion of red blood cells

Journal of Cellular Biochemistry ◽

10.1002/jcb.22600 ◽

2010 ◽

Vol 110 (4) ◽

pp. 882-892 ◽

Cited By ~ 2

Author(s):

Ana Zuleima Obando-Martinez ◽

Hernando Curtidor ◽

Magnolia Vanegas ◽

Gabriela Arévalo-Pinzón ◽

Manuel Alfonso Patarroyo ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Red Blood Cells ◽

Blood Cells ◽

Potential Role ◽

Host Cells ◽

Merozoite Invasion ◽

Conserved Regions

Download Full-text

Identification of Proteins from Plasmodium falciparum That Are Homologous to Reticulocyte Binding Proteins inPlasmodium vivax

Infection and Immunity ◽

10.1128/iai.69.2.1084-1092.2001 ◽

2001 ◽

Vol 69 (2) ◽

pp. 1084-1092 ◽

Cited By ~ 97

Author(s):

Tony Triglia ◽

Jenny Thompson ◽

Sonia R. Caruana ◽

Mauro Delorenzi ◽

Terry Speed ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Red Blood Cells ◽

Molecular Mass ◽

Blood Cells ◽

Potential Role ◽

High Molecular Mass ◽

In Vitro Growth ◽

Merozoite Invasion ◽

Genome Databases

ABSTRACT Plasmodium falciparum infections can be fatal, whileP. vivax infections usually are not. A possible factor involved in the greater virulence of P. falciparum is that this parasite grows in red blood cells (RBCs) of all maturities whereasP. vivax is restricted to growth in reticulocytes, which represent only approximately 1% of total RBCs in the periphery. Two proteins, expressed at the apical end of the invasive merozoite stage from P. vivax, have been implicated in the targeting of reticulocytes for invasion by this parasite. A search of the P. falciparum genome databases has identified genes that are homologous to the P. vivax rbp-1 and -2 genes. Two of these genes are virtually identical over a large region of the 5′ end but are highly divergent at the 3′ end. They encode high-molecular-mass proteins of >300 kDa that are expressed in late schizonts and localized to the apical end of the merozoite. To test a potential role in merozoite invasion of RBCs, we analyzed the ability of these proteins to bind to mature RBCs and reticulocytes. No binding to mature RBCs or cell preparations enriched for reticulocytes was detected. We identified a parasite clone that lacks the gene for one of these proteins, showing that the gene is not required for normal in vitro growth. Antibodies to these proteins can inhibit merozoite invasion of RBCs.

Download Full-text

In Vitro Activities of 25 Quinolones and Fluoroquinolones against Liver and Blood Stage Plasmodium spp

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.47.8.2636-2639.2003 ◽

2003 ◽

Vol 47 (8) ◽

pp. 2636-2639 ◽

Cited By ~ 62

Author(s):

Nassira Mahmoudi ◽

Liliane Ciceron ◽

Jean-François Franetich ◽

Khemais Farhati ◽

Olivier Silvie ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Red Blood Cells ◽

Drug Concentration ◽

Blood Cells ◽

Inhibitory Effect ◽

Plasmodium Yoelii ◽

Prolonged Incubation ◽

Plasmodium Yoelii Yoelii ◽

Effective Drugs

ABSTRACT The in vitro activities of 25 quinolones and fluoroquinolones against erythrocytic stages of Plasmodium falciparum and against liver stages of Plasmodium yoelii yoelii and P. falciparum were studied. All compounds were inhibitory for chloroquine-sensitive and chloroquine-resistant P. falciparum grown in red blood cells. This inhibitory effect increased with prolonged incubation and according to the logarithm of the drug concentration. Grepafloxacin, trovafloxacin, and ciprofloxacin were the most effective drugs, with 50% inhibitory concentrations of <10 μg/ml against both strains. Only grepafloxacin, piromidic acid, and trovafloxacin had an inhibitory effect against hepatic stages of P. falciparum and P. yoelii yoelii; this effect combined reductions of the numbers and the sizes of schizonts in treated cultures. Thus, quinolones have a potential for treatment or prevention of malaria through their unique antiparasitic effect against erythrocytic and hepatic stages of Plasmodium.

Download Full-text

Heterogeneous timing of asexual cycles in Plasmodium falciparum quantified by extended time-lapse microscopy

10.1101/344812 ◽

2018 ◽

Author(s):

Heungwon Park ◽

Shuqiang Huang ◽

Katelyn A. Walzer ◽

Lingchong You ◽

Jen-Tsan Ashley Chi ◽

...

Keyword(s):

Red Blood Cells ◽

Blood Cells ◽

Single Cells ◽

Time Lapse ◽

Bimodal Distribution ◽

Host Cells ◽

Cycle Period ◽

Human Red Blood Cells ◽

Asexual Cycle

ABSTRACTMalarial fever arises from the synchronous bursting of human red blood cells by the Plasmodium parasite. The released parasites re-infect neighboring red blood cells and undergo another asexual cycle of differentiation and proliferation for 48 hours, before again bursting synchronously. The synchrony of bursting is lost during in vitro culturing of the parasite outside the human body, presumably because the asexual cycle is no longer entrained by host-specific circadian cues. Therefore, most in vitro malaria studies have relied on the artificial synchronization of the parasite population. However, much remains unknown about the degree of timing heterogeneity of asexual cycles and how artificial synchronization may affect this timing. Here, we combined time-lapse fluorescence microscopy and long-term culturing to follow single cells and directly measure the heterogeneous timing of in vitro asexual cycles. We first demonstrate that unsynchronized laboratory cultures are not fully asynchronous and the parasites exhibit a bimodal distribution in their first burst times. We then show that synchronized and unsynchronized cultures had similar asexual cycle periods, which indicates that artificial synchronization does not fundamentally perturb asexual cycle dynamics. Last, we demonstrate that sibling parasites descended from the same schizont exhibited significant variation in asexual cycle period, although smaller than the variation between non-siblings. The additional variance between non-siblings likely arises from the variable environments and/or developmental programs experienced in different host cells.

Download Full-text