Plasmodium Berghei ANKA Research Articles

Effects of nanocapsules containing lumefantrine and artemether in an experimental model of cerebral malaria.

Malaria, a tropical neglected disease, imposes a significant burden on global health, leading to the loss of thousands of lives annually. Its gold standard treatment is a combination therapy of lumefantrine (LUM) and artemether (ART). Nanotechnology holds significant potential for improving drug bioavailability and potency while reducing adverse effects. This study aimed to develop lipid-core nanocapsules containing ART and LUM and evaluate their effects in an experimental cerebral malaria model (ECM). The polymeric interfacial deposition method was used to develop lipid-core nanocapsules (LNCs) containing ART and LUM (LNCARTLUM) and were characterized using micrometric and nanometric scales. Male C57BL/6 mice were infected with Plasmodium (P.) berghei ANKA (PbA, 1 × 105 PbA-parasitized red blood cells, intraperitoneally). On day 5 post-infection, PbA-infected mice were orally administered with ART + LUM, LNCARTLUM, blank nanocapsules (LNCBL), or ethanol as a control. Parasitemia, clinical scores, and survival rates were monitored throughout the experiment. Organ-to-body weight ratios, cytokine quantification, and intravital microscopy analyses were conducted on day 7 post-infection. LNCs were successfully developed and characterized. The treatment with LNCARTLUM in ECM resulted in complete clearance of parasitemia at 10 dpi, decreased clinical scores, and maintained 100% survival rates. Thereated mice exhibited splenomegaly and reduced TNF-α, IL-1β, and MCP1 levels in the brain. Furthermore, the LNCARTLUM treatment protected the brain microvasculature, reducing the number of cells in the rolling process and adherent to the microvasculature endothelium. Nanoformulations can potentially improve the efficacy of antimalarial drugs and be considered a promising approach to treat malaria.

Triple Artemisinin-based Combination Therapy (TACT): Efficacy of dihydroartemisinin-piperaquine plus chloroquine against Plasmodium berghei ANKA strains with different drug sensitivities in a murine malaria model.

BackgroundEvident detection of artemisinin resistance markers in patient isolates of Plasmodium falciparum from East Africa threatens the efficacy of artemisinin-based combination therapies (ACTs) as first-line treatment of malaria in sub-Saharan Africa. Repositioning previously used antimalarials as complementary addition to ACTs has been suggested as a viable option to mitigating this threat. This study evaluated the potential benefit of chloroquine (CQ) as a complementary partner to dihydroartemisinin/piperaquine (DHA/PQ) in the treatment of malaria in a mice model. MethodsThe comparative efficacy of the combination of DHA/PQ/CQ and DHA/PQ against two strains of Plasmodium berghei ANKA (MRA 311 and 671) with different levels of sensitivities to chloroquine was evaluated in separate experiments. Parasitological activities including; parasite suppression time, parasite clearance time, recrudescence time, and parasite reduction ratio were evaluated in vivo. The mean survival time was also monitored throughout the duration of the study. ResultsIn both parasite lines, 99.99% chemo-suppression was observed on day 4 in the drug treatment groups (CQ alone, DHA/PQ and DHA/PQ/CQ). In the curative test, there were significant differences between DHA/PQ/CQ and DHQ/PQ treatment, highlighted by reduced parasite clearance time (4.75±0.3 Vs 5.5±0.3 days, P<0.05), significantly delayed recrudescence time (28.5±1.04 Vs 13.3±0.48 days, P<0.01), a 1.5-fold change in parasite reduction ratio, and a prolonged mean survival time (34.5±1.04 Vs 26.7±0.48 days, P<0.05). ConclusionThe addition of chloroquine to dihydroartemisinin-piperaquine may be beneficial in the treatment of malaria, especially in areas where malaria parasite sensitivity to chloroquine is predominant.

Lung Damage Induced by Plasmodium berghei ANKA in Murine Model of Malarial Infection is Mitigated by Dietary Supplementation with DHA-Rich Omega-3.

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are severe complications that can occur in infections caused by any Plasmodium species. Due to the high lethality rate and the lack of specific treatment for ALI/ARDS, studies aimed at understanding and searching for treatment strategies for such complications have been fundamental. Here, we investigated the protective role of dietary supplementation with DHA-rich fish oil against lung damage induced by Plasmodium berghei ANKA in a murine model. Our results demonstrated that alveolar vascular damage, lung edema, and histopathological alterations were significantly reduced in mice that received dietary supplementation compared to those that did not receive the supplementation. Furthermore, a significant reduction in the number of CD8+ T lymphocytes, in addition to reduced infiltration of inflammatory cells in the bronchoalveolar lavage fluid was also observed. High levels of IL-10, but not of TNF-α and IFN-γ, were also observed in infected mice that received the supplementation, along with a reduction in local oxidative stress. Together, the data suggest that dietary supplementation with DHA-rich fish oil in malarial endemic areas may help reduce lung damage resulting from the infection, thus preventing worsening of the condition.

Bovine lactoferrin inhibits Plasmodium berghei growth by binding to heme

Bovine lactoferrin (bLF) is a 77 kDa glycoprotein that is abundant in bovine breast milk and exerts various bioactive functions, including antibacterial and antiviral functions. Few studies have explored bLF activity against parasites. We found that bLF affects hemozoin synthesis by binding to heme, inhibiting heme iron polymerization necessary for Plasmodium berghei ANKA survival in infected erythrocytes, and also binds to hemozoin, causing it to disassemble. In a challenge test, bLF administration inhibited the growth of murine malaria parasites compared to untreated group growth. To determine whether the iron content of bLF affects the inhibition of malaria growth, we tested bLFs containing different amounts of iron (apo-bLF, native-bLF, and holo-bLF), but found no significant difference in their effects. This indicated that the active sites were located within the bLFs themselves. Further studies showed that the C-lobe domain of bLF can inhibit hemozoin formation and the growth of P. berghei ANKA. Evaluation of pepsin degradation products of the C-lobe identified a 47-amino-acid section, C-1, as the smallest effective region that could inhibit hemozoin formation. This study highlights bLF’s potential as a novel therapeutic agent against malaria, underscoring the importance of its non-iron-dependent bioactive sites in combating parasite growth.

Noscapine shows antimalarial activity against Plasmodium falciparum 3D7, its clinical isolate Pf140/SS, and Plasmodium berghei ANKA

Objective: To evaluate the antimalarial activity of noscapine against Plasmodium falciparum 3D7 strain (Pf3D7), its clinical isolate (Pf140/SS), and Plasmodium berghei ANKA (PbA). Methods: Using ring-stage survival assay, phenotypic assessments, and SYBR-green-based fluorescence assay, the antimalarial activities of noscapine were assessed compared with dihydroartemisinin (DHA) in in vivo and in vitro studies. In addition, hemolysis and cytotoxicity tests were carried out to evaluate its safety. RT-PCR assay was also conducted to determine the effect of noscapine on papain-like cysteine protease Plasmodium falciparum falcipain-2 (PfFP-2). Results: The antimalarial efficacy of noscapine against Pf3D7 and Pf140/SS was comparable to DHA, with IC50 values of (7.68±0.88) and (5.57±0.74) nM/mL, respectively, and &gt;95% inhibition of PbA infected rats. Noscapine also showed a safe profile, as evidenced by low hemolysis and cytotoxicity even at high concentrations. Moreover, PfFP-2 expression was significantly inhibited in both noscapine-treated Pf3D7 and Pf140/SS (P&lt;0.01). Conclusions: Noscapine has antimalarial properties comparable to standard antimalarial DHA with better safety profiles, which may be further explored as a therapeutic candidate for the treatment of malaria.

Increased Superoxide Dismuatase (SOD) In Mice Infected by Plasmodium Berghei ANKA Treated with Nanoparticle Extract of Beetroot (Beta Vulgaris L)

BACKGROUND: Malaria infection causes increased free radicals which leads to severity and decreases antioxidant activity, thus increasing the risk of severe malaria complications. Beetroot extract has active compounds that function as anti-inflammatory and antioxidants. Nanoparticles are a technology that can be used to improve drug delivery efficiency in smaller doses. AIMS: to prove the effectiveness of beetroot extract nanoparticles on SOD levels in mice infected with malaria and treated with artemisinin METHOD: An experimental study using a post-test-only randomized control group design. The research sample used 30 male Balb/c mice divided into 6 groups. Group 1 was the healthy group, group 2 was the infected group without treatment, group 3 was the infected group with artemisinin treatment, group 4 was the infected group with artemisinin treatment and 50 mg/kgBW/day beetroot extract nanoparticles, group 5 was the infected group with artemisinin treatment and 100 mg/kg BW/day beetroot extract nanoparticles, and group 6 was the infected group with artemisinin treatment and 200 mg/kg BW/day beetroot extract nanoparticles. Beetroot extract and artemisinin supplementation were given after parasitemia index &gt; 1% and given for 4 days. On the 5th day after therapy, serum SOD levels were measured using ELISA. RESULT: The measurement of SOD levels in the artemisinin group supplemented with nanoparticle extracts of beetroot at doses 100-200 mg/KgBW were 21,48-21,59 ng/ml. Kruskal Wallis and Mann Whitney test showed that they are significantly higher serum SOD levels compared to the infected mice group (p&lt;0.05). CONCLUSION: Supplementation of beetroot extract nanoparticles has an antioxidant effect by increasing SOD levels in mice infected with malaria and receiving artemisinin therapy.

Mouse NOD/Shi and NSY/Hos strains infected with Plasmodium berghei ANKA are models for experimental cerebral malaria.

In humans, cerebral malaria is the most common cause of malaria-related mortality. Mouse C57BL/6 (B6) sub-strains are the major model system for experimental cerebral malaria (ECM) as they show similar pathophysiology to human cerebral malaria after infection with the rodent malaria parasite Plasmodium berghei ANKA. This model system has been used to analyze the molecular mechanisms of cerebral malaria. To develop new mouse models, we analyzed the ECM susceptibility of NOD/Shi (NOD) and NSY/Hos (NSY) strains established from the non-inbred ICR strain. Both NOD and NSY strains exhibited clinical symptoms and pathologies similar to ECM in C57BL/6J (B6J) mice and died within 11 days of infection. Thus, the NOD and NSY strains are susceptible to ECM and may be useful as new ECM models. The ECM susceptibility of both strains is suggested to be due to homozygosity for the cerebral malaria susceptibility allele of the ECM susceptible ICR strain. Although analyses using B6 sub-strains have proposed that complement component 5 (C5) plays an important role in ECM pathogenesis, we found that C5 was not essential as the ECM susceptible NOD strain is C5 deficient. Thus, results obtained from B6 sub-strains may not reflect the full picture of ECM in mice. Comparative analyses of multiple ECM models will contribute to a more accurate identification of the factors essential for ECM.

Circadian Control of the Response of Macrophages to Plasmodium Spp.-Infected Red Blood Cells.

Malaria is a serious vector-borne disease characterized by periodic episodes of high fever and strong immune responses that are coordinated with the daily synchronized parasite replication cycle inside RBCs. As immune cells harbor an autonomous circadian clock that controls various aspects of the immune response, we sought to determine whether the intensity of the immune response to Plasmodium spp., the parasite causing malaria, depends on time of infection. To do this, we developed a culture model in which mouse bone marrow-derived macrophages are stimulated with RBCs infected with Plasmodium berghei ANKA (iRBCs). Lysed iRBCs, but not intact iRBCs or uninfected RBCs, triggered an inflammatory immune response in bone marrow-derived macrophages. By stimulating at four different circadian time points (16, 22, 28, or 34 h postsynchronization of the cells' clock), 24-h rhythms in reactive oxygen species and cytokines/chemokines were found. Furthermore, the analysis of the macrophage proteome and phosphoproteome revealed global changes in response to iRBCs that varied according to circadian time. This included many proteins and signaling pathways known to be involved in the response to Plasmodium infection. In summary, our findings show that the circadian clock within macrophages determines the magnitude of the inflammatory response upon stimulation with ruptured iRBCs, along with changes of the cell proteome and phosphoproteome.

Neurons upregulate PD-L1 via IFN/STAT1/IRF1 to alleviate damage by CD8+ T cells in cerebral malaria

BackgroundCerebral malaria (CM) is the most lethal complication of malaria, and survivors usually endure neurological sequelae. Notably, the cytotoxic effect of infiltrating Plasmodium-activated CD8+ T cells on cerebral microvasculature endothelial cells is a prominent feature of the experimental CM (ECM) model with blood–brain barrier disruption. However, the damage effect of CD8+ T cells infiltrating the brain parenchyma on neurons remains unclear. Based on the immunosuppressive effect of the PD-1/PD-L1 pathway on T cells, our previous study demonstrated that the systemic upregulation of PD-L1 to inhibit CD8+ T cell function could effectively alleviate the symptoms of ECM mice. However, it has not been reported whether neurons can suppress the pathogenic effect of CD8+ T cells through the PD-1/PD-L1 negative immunomodulatory pathway. As the important inflammatory factor of CM, interferons can induce the expression of PD-L1 via different molecular mechanisms according to the neuro-immune microenvironment. Therefore, this study aimed to investigate the direct interaction between CD8+ T cells and neurons, as well as the mechanism of neurons to alleviate the pathogenic effect of CD8+ T cells through up-regulating PD-L1 induced by IFNs.MethodsUsing the ECM model of C57BL/6J mice infected with Plasmodium berghei ANKA (PbA), morphological observations were conducted in vivo by electron microscope and IF staining. The interaction between the ECM CD8+ T cells (immune magnetic bead sorting from spleen of ECM mice) and primary cultured cortical neurons in vitro was observed by IF staining and time-lapse photography. RNA-seq was performed to analyze the signaling pathway of PD-L1 upregulation in neurons induced by IFNβ or IFNγ, and verified through q-PCR, WB, IF staining, and flow cytometry both in vitro and in vivo using IFNAR or IFNGR gene knockout mice. The protective effect of adenovirus-mediated PD-L1 IgGFc fusion protein expression was verified in ECM mice with brain stereotaxic injection in vivo and in primary cultured neurons via viral infection in vitro.ResultsIn vivo, ECM mice showed infiltration of activated CD8+ T cells and neuronal injury in the brain parenchyma. In vitro, ECM CD8+ T cells were in direct contact with neurons and induced axonal damage, as an active behavior. The PD-L1 protein level was elevated in neurons of ECM mice and in primary cultured neurons induced by IFNβ, IFNγ, or ECM CD8+ T cells in vitro. Furthermore, the IFNβ or IFNγ induced neuronal expression of PD-L1 was mediated by increasing STAT1/IRF1 pathway via IFN receptors. The increase of PD-L1 expression in neurons during PbA infection was weakened after deleting the IFNAR or IFNGR. Increased PD-L1 expression by adenovirus partially protected neurons from CD8+ T cell-mediated damage both in vitro and in vivo.ConclusionOur study demonstrates that both type I and type II IFNs can induce neurons to upregulate PD-L1 via the STAT1/IRF1 pathway mediated by IFN receptors to protect against activated CD8+ T cell-mediated damage, providing a targeted pathway to alleviate neuroinflammation during ECM.Graphical

Involvement of Inflammatory Cytokines, Renal NaPi-IIa Cotransporter, and TRAIL Induced-Apoptosis in Experimental Malaria-Associated Acute Kidney Injury.

The murine model of experimental cerebral malaria (ECM) induced by Plasmodium berghei ANKA was used to investigate the relationship among pro-inflammatory cytokines, alterations in renal function biomarkers, and the induction of the TRAIL apoptosis pathway during malaria-associated acute kidney injury (AKI). Renal function was evaluated through the measurement of plasma creatinine and blood urea nitrogen (BUN). The mRNA expression of several cytokines and NaPi-IIa was quantified. Kidney sections were examined and cytokine levels were assessed using cytometric bead array (CBA) assays. The presence of glomerular IgG deposits and apoptosis-related proteins were investigated using in situ immunofluorescence assays and quantitative real-time PCR, respectively. NaPi-IIa downregulation in the kidneys provided novel insights into the pathogenesis of hypophosphatemia during CM. Histopathological analysis revealed characteristic features of severe malaria-associated nephritis, including glomerular collapse and tubular alterations. Pro-inflammatory cytokines, such as TNF-α, IL-1β, and IL-6, were upregulated. The TRAIL apoptosis pathway was significantly activated, implicating its role in renal apoptosis. The observed alterations in renal biomarkers and the downregulation of NaPi-IIa shed light on potential mechanisms contributing to renal dysfunction in ECM. The intricate balance between pro- and anti-inflammatory cytokines, along with the activation of the TRAIL apoptosis pathway, highlights the complexity of malaria-associated AKI and provides new therapeutic targets.

Oral administration of IPI549 protects mice from neuropathology and an overwhelming inflammatory response during experimental cerebral malaria

Infection with Plasmodium falciparum is often deadly when it results in cerebral malaria, which is associated with neuropathology described as an overwhelming inflammatory response and mechanical obstruction of cerebral microvascular. PI3Kγ is a critical component of intracellular signal transduction and plays a central role in regulating cell chemotaxis, migration, and activation. The purpose of this study was to examine the relationship between inhibiting the PI3Kγ pathway and the outcome of experimental cerebral malaria (ECM) in C57BL/6J mice infected with the mouse malaria parasite, Plasmodium berghei ANKA. We observed that oral administration of the PI3Kγ inhibitor IPI549 after infection completely protected mice from ECM. IPI549 treatment significantly dampened the magnitude of inflammatory responses, with reduced production of pro-inflammatory factors, decreased T cell activation, and altered differentiation of antigen-presenting cells. IPI549 treatment protected the infected mice from neuropathology, as assessed by an observed reduction of pathogenic T cells in the brain. Treating the infected mice with IPI549 three days after parasite inoculation improved the murine blood brain barrier (BBB) integrity and helped the mice pass the onset of ECM. Together, these data indicate that oral administration of the PI3Kγ inhibitor IPI549 has a suppressive role in host inflammation and alleviates cerebral pathology, which supports IPI549 as a new malaria treatment option with potential therapeutic implications for cerebral malaria.

Antimalarial potential of Kerala Ayurvedic Water "Pathimugam".

The persistent threat of drug resistant malaria demands new cures. Low prevalence of malaria in the Indian state of Kerala compared with other proximal states led us to explore if there is any traditional practice in Kerala which may confer protection against malaria. In this context, our attention was drawn to "Pathimugam" i.e., Ceasalpinia sappan whose heartwood is used to prepare a red aqueous extract which is a uniquely popular drink all over Kerala. Aqueous and methanolic extracts of various organs of C. sappan were prepared and tested against Plasmodium falciparum grown in vitro culture using SYBR Green-I assay. The cytotoxicity of active extracts/fractions was studied using mammalian HeLa cell line. In vivo efficacy was determined using Plasmodium berghei ANKA infected mice. The highest antiplasmodial activities in the alcoholic and aqueous extracts were observed in leaf methanolic extract (IC 2 μg/ml) and heartwood aqueous extract (IC 12.5 μg/ml). C. sappan extracts were equipotent against both chloroquine sensitive Pf3D7 and resistant Pf INDO strains and showed suppression of % parasitemia in P. berghei infected mice. Activity guided chromatographic fractionation of aqueous wood extract led to the fortification of antiplasmodial activity (IC 5 μg/ml). Our results establish the antiplasmodial potential of C. sappan and suggest that its regular use might have prophylactic or curative actions that may assist in keeping check on malaria in the Indian state of Kerala.

In vivo antimalarial effect of 1-hydroxy-5,6,7-trimethoxyxanthone isolated from Mammea siamensis T. Anders. flowers: pharmacokinetic and acute toxicity studies

BackgroundThe potent antiplasmodial activity of 1-hydroxy-5,6,7-trimethoxyxanthone (HTX), isolated from Mammea siamensis T. Anders. flowers, has previously been demonstrated in vitro. However, its in vivo activity has not been reported. Therefore, this study aimed to investigate the antimalarial activity and acute toxicity of HTX in a mouse model and to evaluate the pharmacokinetic profile of HTX following a single intraperitoneal administration.MethodsThe in vivo antimalarial activity of HTX was evaluated using a 4-day suppressive test. Mice were intraperitoneally injected with Plasmodium berghei ANKA strain and given HTX daily for 4 days. To detect acute toxicity, mice received a single dose of HTX and were observed for 14 days. Additionally, the biochemical parameters of the liver and kidney functions as well as the histopathology of liver and kidney tissues were examined. HTX pharmacokinetics after intraperitoneal administration was also investigated in a mouse model. Liquid chromatography triple quadrupole mass spectrometry was used to quantify plasma HTX and calculate pharmacokinetic parameters with the PKSolver software.ResultsHTX at 10 mg/kg body weight significantly suppressed parasitemia in malaria-infected mice by 74.26%. Mice treated with 3 mg/kg HTX showed 46.88% suppression, whereas mice treated with 1 mg/kg displayed 34.56% suppression. Additionally, no symptoms of acute toxicity were observed in the HTX-treated groups. There were no significant alterations in the biochemical parameters of the liver and kidney functions and no histological changes in liver or kidney tissues. Following intraperitoneal HTX administration, the pharmacokinetic profile exhibited a maximum concentration (Cmax) of 94.02 ng/mL, time to attain Cmax (Tmax) of 0.5 h, mean resident time of 14.80 h, and elimination half-life of 13.88 h.ConclusionsHTX has in vivo antimalarial properties against P. berghei infection. Acute toxicity studies of HTX did not show behavioral changes or mortality. The median lethal dose was greater than 50 mg/kg body weight. Pharmacokinetic studies showed that HTX has a long elimination half-life; hence, shortening the duration of malaria treatment may be required to minimize toxicity.

Effect of moringa extract on parasitemia, monocyte activation and organomegaly among Mus musculus infected by Plasmodium berghei ANKA.

In Indonesia, malaria remains a problem, with 94,610 active cases in 2021 and its current therapy includes chloroquine and artemisinin; however, resistance has been commonly reported. To overcome this problem, studies about potential medicinal plants that can be used as antimalaria, such as moringa (Moringa oleifera) started to receive more attention. The aim of this study was to investigate the effects of moringa in parasitemia, monocyte activation, and organomegaly on animal model malaria. This experimental study used male Mus musculus, infected by Plasmodium berghei ANKA, as an animal malaria model. The extract was made by maceration of dry moringa leaves, which were then divided into three concentrations: 25%, 50%, and 75%. Dihydroartemisinin-piperazine was used as a positive control treatment, and distilled water as a negative control treatment. The animals were observed for six days to assess the parasitemia count and the number of monocyte activation. On day 7, the animals were terminated, and the liver, spleen, and kidney were weighed. The results showed that the effective concentrations in reducing parasitemia and inducing monocyte activation were 50% and 25% of moringa leaf extract, respectively. The smallest liver and spleen enlargement was observed among animals within the group treated with a 50% concentration of M. oleifera extract. In contrast, the smallest kidney enlargement was observed in the group treated with 25% of M. oleifera extract. Further analysis is recommended to isolate compounds with antimalarial properties in moringa leaves.

Navigating the terrain of neutrophil extracellular traps in severe malaria pathogenesis

Du, Ren, et al. recently showed in a Plasmodium berghei ANKA (PbA) experimental malaria model that phosphatase of regenerating liver 2 (PRL2) regulates neutrophil extracellular traps (NETs) in severe malaria (SM)-related acute lung injury (ALI). PRL2 deficiency caused SM with ALI in a mouse model by increasing NETs in pulmonary tissue; hydroxychloroquine (HCQ) may ameliorate this.

Synthetic angiotensin II peptide derivatives confer protection against cerebral and severe non-cerebral malaria in murine models

Malaria can have severe long-term effects. Even after treatment with antimalarial drugs eliminates the parasite, survivors of cerebral malaria may suffer from irreversible brain damage, leading to cognitive deficits. Angiotensin II, a natural human peptide hormone that regulates blood pressure, has been shown to be active against Plasmodium spp., the etiologic agent of malaria. Here, we tested two Ang II derivatives that do not elicit vasoconstriction in mice: VIPF, a linear tetrapeptide, which constitutes part of the hydrophobic portion of Ang II; and Ang II-SS, a disulfide-bridged derivative. The antiplasmodial potential of both peptides was evaluated with two mouse models: an experimental cerebral malaria model and a mouse model of non-cerebral malaria. The latter consisted of BALB/c mice infected with Plasmodium berghei ANKA. The peptides had no effect on mean blood pressure and significantly reduced parasitemia in both mouse models. Both peptides reduced the SHIRPA score, an assay used to assess murine health and behavior. However, only the constrained derivative (Ang II-SS), which was also resistant to proteolytic degradation, significantly increased mouse survival. Here, we show that synthetic peptides derived from Ang II are capable of conferring protection against severe manifestations of malaria in mouse models while overcoming the vasoconstrictive side effects of the parent peptide.

IL-15 Complex-Induced IL-10 Enhances Plasmodium-specific CD4+ T Follicular Helper Differentiation and Antibody Production.

Malaria, which results from infection with Plasmodium parasites, remains a major public health problem. Although humans do not develop long-lived, sterilizing immunity, protection against symptomatic disease develops after repeated exposure to Plasmodium parasites and correlates with the acquisition of humoral immunity. Despite the established role Abs play in protection from malaria disease, dysregulated inflammation is thought to contribute to the suboptimal immune response to Plasmodium infection. Plasmodium berghei ANKA (PbA) infection results in a fatal severe malaria disease in mice. We previously demonstrated that treatment of mice with IL-15 complex (IL-15C; IL-15 bound to an IL-15Rα-Fc fusion protein) induces IL-10 expression in NK cells, which protects mice from PbA-induced death. Using a novel MHC class II tetramer to identify PbA-specific CD4+ T cells, in this study we demonstrate that IL-15C treatment enhances T follicular helper (Tfh) differentiation and modulates cytokine production by CD4+ T cells. Moreover, genetic deletion of NK cell-derived IL-10 or IL-10R expression on T cells prevents IL-15C-induced Tfh differentiation. Additionally, IL-15C treatment results in increased anti-PbA IgG Ab levels and improves survival following reinfection. Overall, these data demonstrate that IL-15C treatment, via its induction of IL-10 from NK cells, modulates the dysregulated inflammation during Plasmodium infection to promote Tfh differentiation and Ab generation, correlating with improved survival from reinfection. These findings will facilitate improved control of malaria infection and protection from disease by informing therapeutic strategies and vaccine design.

Blockage of mechanosensitive Piezo1 channel alleviates the severity of experimental malaria-associated acute lung injury

BackgroundMalaria-associated acute lung injury (MA-ALI) is a well-recognized clinical complication of severe, complicated malaria that is partly driven by sequestrations of infected red blood cells (iRBCs) on lung postcapillary induced impaired blood flow. In earlier studies the mechanosensitive Piezo1 channel emerged as a regulator of mechanical stimuli, but the function and underlying mechanism of Piezo1 impacting MA-ALI severity via sensing the impaired pulmonary blood flow are still not fully elucidated. Thus, the present study aimed to explore the role of Piezo1 in the severity of murine MA-ALI.MethodsHere, we utilized a widely accepted murine model of MA-ALI using C57BL/6 mice with Plasmodium berghei ANKA infection and then added a Piezo1 inhibitor (GsMTx4) to the model. The iRBC-stimulated Raw264.7 macrophages in vitro were also targeted with GsMTx4 to further explore the potential mechanism.ResultsOur data showed an elevation in the expression of Piezo1 and number of Piezo1+-CD68+ macrophages in lung tissues of the experimental MA-ALI mice. Compared to the infected control mice, the blockage of Piezo1 with GsMTx4 dramatically improved the survival rate but decreased body weight loss, peripheral blood parasitemia/lung parasite burden, experimental cerebral malaria incidence, total protein concentrations in bronchoalveolar lavage fluid, lung wet/dry weight ratio, vascular leakage, pathological damage, apoptosis and number of CD68+ and CD86+ macrophages in lung tissues. This was accompanied by a dramatic increase in the number of CD206+ macrophages (M2-like subtype), upregulation of anti-inflammatory cytokines (e.g. IL-4 and IL-10) and downregulation of pro-inflammatory cytokines (e.g. TNF-α and IL-1β). In addition, GsMTx4 treatment remarkably decreased pulmonary intracellular iron accumulation, protein level of 4-HNE (an activator of ferroptosis) and the number of CD68+-Piezo1+ and CD68+-4-HNE+ macrophages but significantly increased protein levels of GPX4 (an inhibitor of ferroptosis) in experimental MA-ALI mice. Similarly, in vitro study showed that the administration of GsMTx4 led to a remarkable elevation in the mRNA levels of CD206, IL-4, IL-10 and GPX-4 but to a substantial decline in CD86, TNF-α, IL-1β and 4-HNE in the iRBC-stimulated Raw264.7 cells.ConclusionsOur findings indicated that blockage of Piezo1 with GsMTx4 alleviated the severity of experimental MA-ALI in mice partly by triggering pulmonary macrophage M2 polarization and subsequent anti-inflammatory responses but inhibited apoptosis and ferroptosis in lung tissue. Our data suggested that targeting Piezo1 in macrophages could be a promising therapeutic strategy for treating MA-ALI.Graphical

Lycopene supplementation promoted increased survival and decreased parasitemia in mice with severe malaria: comparison with N-acetylcysteine.

Oxidative stress is involved in the pathogenesis of malaria, causing anemia, respiratory complications, and cerebral malaria. To mitigate oxidative stress, we investigated the effect of nutritional supplementation whit lycopene (LYC) on the evolution of parasitemia and survival rate in mice infected with Plasmodium berghei ANKA (Pb), comparing to the effects promoted by N-acetylcysteine (NAC). Therefore, 175 mice were randomly distributed into 4 groups; Sham: untreated and uninfected animals; Pb: animals infected with Pb; LYC+Pb: animals treated with LYC and infected with Pb; NAC+Pb: animals treated with NAC and infected with Pb. The animals were followed for 12 days after infection, and survival and parasitemia rates were evaluated. There was a 40.1% increase in parasitemia in the animals of the Pb group on the 12th day, and a survival rate of 45%. LYC supplementation slowed the development of parasitemia to 19% and promoted a significative increase in the survival rate of 80% on the 12th day after infection, compared to the Pb group, effects superior to those promoted by NAC, providing strong evidence of the beneficial effect of LYC on in vivo malaria and stressing the importance of antioxidant supplementation in the treatment of this disease.

N-(coumarin-3-yl)cinnamamide Promotes Immunomodulatory, Neuroprotective, and Lung Function-Preserving Effects during Severe Malaria.

Plasmodium berghei ANKA (PbA) infection in mice resembles several aspects of severe malaria in humans, such as cerebral malaria and acute respiratory distress syndrome. Herein, the effects of N-(coumarin-3-yl)cinnamamide (M220) against severe experimental malaria have been investigated. Treatment with M220 proved to protect cognitive abilities and lung function in PbA-infected mice, observed by an object recognition test and spirometry, respectively. In addition, treated mice demonstrated decreased levels of brain and lung inflammation. The production and accumulation of microglia, and immune cells that produce the inflammatory cytokines TNF and IFN-γ, decreased, while the production of the anti-inflammatory cytokine IL-10 by innate and adaptive immune cells was enhanced. Treatment with M220 promotes immunomodulatory, neuroprotective, and lung function-preserving effects during experimental severe malaria. Therefore, it may be an interesting therapeutic candidate to treat severe malaria effects.