Further evidence for an anti-inflammatory role of artesunate in experimental cerebral malaria

Interplay Between the Immune and Nervous Cognitive Systems in Homeostasis and in Malaria

The immune and nervous systems can be thought of as cognitive and plastic systems, since they are both involved in cognition/recognition processes and can be architecturally and functionally modified by experience, and such changes can influence each other's functioning. The immune system can affect nervous system function depending on the nature of the immune stimuli and the pro/anti-inflammatory responses they generate. Here we consider interactions between the immune and nervous systems in homeostasis and disease, including the beneficial and deleterious effects of immune stimuli on brain function and the impact of severe and non-severe malaria parasite infections on neurocognitive and behavioral parameters in human and experimental murine malaria. We also discuss the effect of immunization on the reversal of cognitive deficits associated with experimental non-severe malaria in a model susceptible to the development of the cerebral form of the illness. Finally, we consider the possibility of using human vaccines, largely exploited as immune-prophylactics for infectious diseases, as therapeutic tools to prevent or mitigate the expression of cognitive deficits in infectious and chronic degenerative diseases.

Vitamin D receptor (VDR) on the cell membrane of mouse macrophages participates in the formation of lipopolysaccharide tolerance: mVDR is related to the effect of artesunate to reverse LPS tolerance

It is unclear whether membrane vitamin D receptor (mVDR) exists on the macrophage membrane or whether mVDR is associated with lipopolysaccharide (LPS) tolerance. Herein, we report that interfering with caveolae and caveolae-dependent lipid rafts inhibited the formation of LPS tolerance. VDR was detected as co-localized with membrane molecular markers. VDR was detected on the cell membrane and its level was higher in LPS-tolerant cells than that in only LPS treatment cells. Anti-VDR antibodies could abolish the effect of artesunate (AS) to reverse LPS tolerance, and the wild-type peptides (H397 and H305) of VDR, but not the mutant peptide (H397D and H305A), led to the loss of AS's effect. AS decreased the mVDR level in LPS-tolerant cells. In vivo, AS significantly reduced VDR level in the lung tissue of LPS-tolerant mice. In summary, mVDR exists on the cell membrane of macrophages and is closely associated with the formation of LPS tolerance and the effects of AS. Video Abstract.

Medicinal and mechanistic overview of artemisinin in the treatment of human diseases

Artemisinin (ART) is a bioactive compound isolated from the plant Artemisia annua and has been traditionally used to treat conditions such as malaria, cancer, viral infections, bacterial infections, and some cardiovascular diseases, especially in Asia, North America, Europe and other parts of the world. This comprehensive review aims to update the biomedical potential of ART and its derivatives for treating human diseases highlighting its pharmacokinetic and pharmacological properties based on the results of experimental pharmacological studies in vitro and in vivo. Cellular and molecular mechanisms of action, tested doses and toxic effects of artemisinin were also described. The analysis of data based on an up-to-date literature search showed that ART and its derivatives display anticancer effects along with a wide range of pharmacological activities such as antibacterial, antiviral, antimalarial, antioxidant and cardioprotective effects. These compounds have great potential for discovering new drugs used as adjunctive therapies in cancer and various other diseases. Detailed translational and experimental studies are however needed to fully understand the pharmacological effects of these compounds.

Retinal safety and toxicity study of artesunate in vitro and in vivo

Background

Artesunate (ART), a member of the artemisinin family, possesses multi-properties, including anti-inflammation, anti-oxidation, and anti-tumor. ART was recently reported to show anti-neovascularization effect on the cornea, iris, and retina. Compared to the expensive anti-VEGF treatment, this versatile, economical treatment option is attractive in the ophthalmic field. The safety and toxicity profile of ART intravitreal application are in utmost need.

Methods

In this study, immortalized microglial (IMG) cells were treated with ART to determine the safe concentrations without inducing overt inflammatory reactions. Reverse transcription-polymerase chain reaction analysis was used to detect the cytokine expressions in IMG cells in response to ART stimulation. Various doses of ART were intravitreally injected into the right eyes of C57BL/6 mice. Retinal function was tested by electroretinogram, and retinal ganglion cell (RGC) survival was evaluated by counting Brn3a stained cells in flat-mounted retinas at 7 days after ART injection.

Results

ART below 5μM was safe for IMG cells in vitro. Both 2.5 and 5 ​μM ART treatment increased IL-10 gene expression in IMG cells while not changing IL-1β, IL-6, TNF-α, and Arg-1. In the in vivo study, intravitreal injection of ART below 100 ​μM did not cause deterioration in the retinal function and RGC survival of the mouse eyes, while 1 ​mM ART treatment significantly attenuated both the scotopic and photopic b-wave amplitudes and impaired RGC survival. In addition, treatment with ART of 25, 50, and 100 ​μM significantly decreased TNF-α gene expression while ART of 100 ​μM significantly increased IL-10 in the mouse retina.

Conclusions

Intravitreal injection of 100 ​μM ART could downregulate TNF-α while upregulate IL-10 in the mouse retina without causing retinal functional deterioration and RGC loss. ART might be used as anti-inflammatory agent for retinal disorders.

UHPLC-MS and GC-MS phytochemical profiling, amelioration of pain and inflammation with chloroform extract of Funaria hygrometrica Hedw. via modulation of inflammatory biomarkers

People of Pakistan have undisturbed customs for the employment of medicinal plants for healthcare requisites. Chloroform extract of F. hygrometrica (CE FH) was examined for its ability to reduce inflammation and to produce analgesia. Carrageenan and formalin-induced paw edema model for inflammatory activity, hot-plate and tail-flick methods to assess analgesic activity were executed. Phytochemical analysis was done by UHPLC-MS and GC-mass spectrometer. The results demonstrated that in carrageenan-induced paw edema, maximum reduction in inflammation was observed at 5th hour at the dose 100 mg/kg; while at doses 250 and 500 mg/kg, maximum response was observed at 5th and 6th hours. Analgesic activity results indicated that maximum analgesia was observed up to 120 min at 100 mg/kg, while up to 90 min in case of 250 and 500 mg/kg doses. The formalin-induced rat paw edema showed significant (p < 0.05) anti-inflammatory activity after 5 days treatment. After, testing period of 10 days, the biochemical parameters such as CBC, CRP, serum enzymes like CAT, SOD, GSH and inflammatory mediators like TNF-α, IL-6, IL-4 and IL-10 were estimated. The administration of formalin resulted in an increase in the level of leucocytes, total WBC, CRP, serum enzymes and in the diameters of paw thickness, while pre-treatment with CE FH at dose levels of 100, 250 and 500 mg/kg exhibited a diminution in the levels of SOD, GSH, CAT, total RBC and HB. Acute inflammatory mediators such as TNFα, IL -6 and IL-4 were reduced, and IL-10 was upregulated in the treated group as compared to the control. Many phytoconstituents, i.e., chitobiose, chlorovulone III, γ-tocotrienol, emmotin, cassine, hexacosanedioic acid, neophytadiene, fumaric acid, neophytadiene, hexadecanoic acid, phytol and stigmasterol were detected during UHPLC-MS and GC-MS analysis seems to be responsible for the said activity in correlation with the already reported data about these compounds. The results concluded that CE FH possess noteworthy anti-inflammatory and central analgesic action at different doses (100, 250 and 500 mg/kg).

Inflammasomes as biomarkers and therapeutic targets in traumatic brain injury and related-neurodegenerative diseases: A comprehensive overview

Given the ambiguity surrounding traumatic brain injury (TBI) pathophysiology and the lack of any Food and Drug Administration (FDA)-approved neurotherapeutic drugs, there is an increasing need to better understand the mechanisms of TBI. Recently, the roles of inflammasomes have been highlighted as both potential therapeutic targets and diagnostic markers in different neurodegenerative disorders. Indeed, inflammasome activation plays a pivotal function in the central nervous system (CNS) response to many neurological conditions, as well as to several neurodegenerative disorders, specifically, TBI. This comprehensive review summarizes and critically discusses the mechanisms that govern the activation and assembly of inflammasome complexes and the major methods used to study inflammasome activation in TBI and its implication for other neurodegenerative disorders. Also, we will review how inflammasome activation is critical in CNS homeostasis and pathogenesis, and how it can impact chronic TBI sequalae and increase the risk of developing neurodegenerative diseases. Additionally, we discuss the recent updates on inflammasome-related biomarkers and the potential to utilize inflammasomes as putative therapeutic targets that hold the potential to better diagnose and treat subjects with TBI.

The monoterpene 1,8-cineole prevents cerebral edema in a murine model of severe malaria

1,8-Cineole is a naturally occurring compound found in essential oils of different plants and has well-known anti-inflammatory and antimicrobial activities. In the present work, we aimed to investigate its potential antimalarial effect, using the following experimental models: (1) the erythrocytic cycle of Plasmodium falciparum; (2) an adhesion assay using brain microvascular endothelial cells; and (3) an experimental cerebral malaria animal model induced by Plasmodium berghei ANKA infection in susceptible mice. Using the erythrocytic cycle of Plasmodium falciparum, we characterized the schizonticidal effect of 1,8-cineole. This compound decreased parasitemia in a dose-dependent manner with a half maximal inhibitory concentration of 1045.53 ± 63.30 μM. The inhibitory effect of 972 μM 1,8-cineole was irreversible and independent of parasitemia. Moreover, 1,8-cineole reduced the progression of intracellular development of the parasite over 2 cycles, inducing important morphological changes. Ultrastructure analysis revealed a massive loss of integrity of endomembranes and hemozoin crystals in infected erythrocytes treated with 1,8-cineole. The monoterpene reduced the adhesion index of infected erythrocytes to brain microvascular endothelial cells by 60%. Using the experimental cerebral malaria model, treatment of infected mice for 6 consecutive days with 100 mg/kg/day 1,8-cineole reduced cerebral edema with a 50% reduction in parasitemia. Our data suggest a potential antimalarial effect of 1,8-cineole with an impact on the parasite erythrocytic cycle and severe disease.

Mechanism and effects of artesunate on the liver function of rats with type 1 diabetic periodontitis

Periodontitis is an inflammatory disease of the gums. Periodontitis in patients with diabetes can aggravate insulin resistance, but its molecular and biological mechanism remains unclear. This study aimed to explore the effects of diabetic periodontitis on liver function and determine the mechanism by which artesunate improves liver function. Rats with streptozotocin-induced diabetes were divided into five groups, i.e., normal control group (NC group), diabetic periodontitis group (DM+PD group), artesunate intervention group (ART group), insulin intervention group (INS group), and combined medication intervention group (ART+INS group). Drug interventions were then administered to the rats in each group as follows: 50 mg/kg artesunate to the ART group, 6 U/kg insulin to the INS group, and 50 mg/kg artesunate + 6 U/kg insulin to the ART+INS group. Blood samples, liver tissues, and the maxillary alveolar bone were collected post-sacrifice. ART was found to significantly ameliorate hyperglycemia, blood lipid levels, and liver function. The levels of inflammatory factors reduced; the effect was more pronounced in the ART+INS group. Artesunate presumably inhibits the TLR4/NF-κB signaling pathway and expression of downstream inflammatory factors, thereby exerting a protective effect on diabetes-related liver function. This offers a fresh approach to treat diabetes mellitus.

Effectiveness of artesunate combined with fractional CO2 laser in a hypertrophic scar model with underlying mechanism

BACKGROUND AND OBJECTIVES

Both artesunate and fractional CO2 laser have been proved effective in the treatment of hypertrophic scars, yet little data are available for the efficacy of artesunate combined with fractional CO2 laser. In order to assess the pre-clinical significance and the underlying mechanism of this combined treatment profile, we attempted to observe the effectiveness of this therapy in rabbit models through determining the expression of BMP-7 and Fas.

MATERIALS AND METHODS

Twenty-Four New Zealand white rabbits with established hypertrophic scar samples were randomly divided into control group and three treatment groups. Artesunate (20 μl/cm2) was injected into the rat's scar of artesunate and combination groups, while fractional CO2 laser (Combo mode, deep energy:10 mJ, super energy: 50 mJ) was applied to rats in fractional CO2 laser and combination groups at week 4 after model establishment. All rabbits underwent a total of 3 sessions of treatment once every 2 weeks. Histological and immunohistochemistry study, Western blot assay, cell viability, ELISA and RT-QPCR were performed at week 10 to observe the aspects of hypertrophic scar sample changes and expression of BMP-7 and Fas in the scar tissues.

RESULTS

Compared with control group, hypertrophic scars and the collagen fibers were significantly inhibited after treatment, and higher inhibition was seen in the samples in combination group compared to that in artesunate and fractional CO2 laser groups (P < 0.01). Meanwhile, BMP-7 and Fas expressions were both notably increased in all treatment groups, and upregulation of the two proteins was dominant in combination group (P < 0.01).

CONCLUSIONS

Artesunate combined with fractional CO2 laser is effective in hypertrophic scarring in this rabbit model. Our findings can serve as a potential alternative strategy to treatment of hypertrophic scar in clinical practice.

Verifying the outcomes of artesunate plus 595-nm PDL in hypertrophic scars via determining BMP-7 and Fas level in model rabbits

BACKGROUND AND OBJECTIVES

Single-use of artesunate (ART) or 595-nm pulsed-dye laser (PDL) has proven clinical efficacy in the treatment of hypertrophic scars (HSs), yet little research has been done on the combined use of ART and PDL. Bone morphogenetic protein-7 (BMP-7) and Fas are recognized to be two important proteins in reducing scar formation. This study was designed to observe the effect of ART combined with 595-nm PDL in the treatment of HS in rabbit models, and investigate the effect of such protocol on the expression of BMP-7 and Fas in rabbit models.

STUDY DESIGN/MATERIALS AND METHODS

Twenty-four New Zealand white rabbits were randomly divided into the control group, ART group, PDL group, and combined treatment (ART + PDL) group. ART was respectively applied to the ART group and combined treatment group. Treatment was once every 2-week for a total of three sessions for both groups. Animals in the PDL group were simply treated with 595-nm PDL. Then, hematoxylin & eosin and Van Gieson straining, immunohistochemical study, enzyme-linked immunosorbent assay (ELISA), Cell counting kit-8 test, western blot assay, and real-time polymerase chain reaction (RT-PCR) were carried out to observe the development of HS samples and expression of BMP-7 and Fas proteins in the sample tissues.

RESULTS

After treatment, the scar samples grew lower and flatter, which was particularly evident in the combined treatment group, with notably inhibited fibroblast and collagen compared to other groups (p < 0.001). Western blot assay and RT-PCR demonstrated that the expression of BMP-7 was most increased in scar samples treated by ART + PDL. BMP-7 level was correspondingly and notably upregulated in treatment groups, especially in the ART + PDL group. In addition, relevant expression of Fas was also higher after treatment, especially in the ART + PDL group compared to either ART or 595-nm PDL group. The difference was significant among groups (p < 0.001).

CONCLUSIONS

Combined use of ART and 595-nm PDL can inhibit HSs in rabbit models via inhibiting extra fibroblast and collagens. The potential mechanism may be involved in enhanced BMP-7 and Fas expression. Our observations may create an alternative therapeutic strategy for HSs in the clinic.

Artesunate strongly modulates myeloid and regulatory T cells to prevent LPS-induced systemic inflammation

Lipopolysaccharide (LPS) is the major component of the outer membrane of Gram-negative bacteria and is usually administrated to establish models of inflammation. Artesunate (ART), a water-soluble artemisinin derivative, displays multiple pharmacological actions against tumors, viral infections, and inflammation, and has been used as a therapeutic weapon against malaria. In this study, our aim was to evaluate whether ART pretreatment is capable of preventing inflammation induced by LPS. BALB/c mice were treated with 100 mg/kg of ART i.p. for 7 days followed by a single dose of LPS. ART pretreatment led to an improvement in clinical score, prevented alterations in biochemical markers, and reestablished the platelet counts. Flow cytometry analysis showed that ART protected the inflammation mainly by reducing the percentage of M1 macrophages while increasing M2 macrophages and a reestablishment of classical monocytes in the BM. In the spleen, ART pretreatment increased N2 neutrophils, myeloid-derived suppressor cells (MDSC), and regulatory T cells, the latter was also increased in peripheral blood. In addition, a marked decrease in inflammatory cytokines and chemokines was observed in the ART treated group. Our data suggest that ART prevents inflammation, reducing tissue damage and restoring homeostasis.

Parenteral artemisinins are associated with reduced mortality and neurologic deficits and improved long-term behavioral outcomes in children with severe malaria

BACKGROUND

In 2011, the World Health Organization recommended injectable artesunate as the first-line therapy for severe malaria (SM) due to its superiority in reducing mortality compared to quinine. There are limited data on long-term clinical and neurobehavioral outcomes after artemisinin use for treatment of SM.

METHODS

From 2008 to 2013, 502 Ugandan children with two common forms of SM, cerebral malaria and severe malarial anemia, were enrolled in a prospective observational study assessing long-term neurobehavioral and cognitive outcomes following SM. Children were evaluated a week after hospital discharge, and 6, 12, and 24 months of follow-up, and returned to hospital for any illness. In this study, we evaluated the impact of artemisinin derivatives on survival, post-discharge hospital readmission or death, and neurocognitive and behavioral outcomes over 2 years of follow-up.

RESULTS

346 children received quinine and 156 received parenteral artemisinin therapy (artemether or artesunate). After adjustment for disease severity, artemisinin derivatives were associated with a 78% reduction in in-hospital mortality (adjusted odds ratio, 0.22; 95% CI, 0.07-0.67). Among cerebral malaria survivors, children treated with artemisinin derivatives also had reduced neurologic deficits at discharge (quinine, 41.7%; artemisinin derivatives, 23.7%, p=0.007). Over a 2-year follow-up, artemisinin derivatives as compared to quinine were associated with better adjusted scores (negative scores better) in internalizing behavior and executive function in children irrespective of the age at severe malaria episode. After adjusting for multiple comparisons, artemisinin derivatives were associated with better adjusted scores in behavior and executive function in children <6 years of age at severe malaria exposure following adjustment for child age, sex, socioeconomic status, enrichment in the home environment, and the incidence of hospitalizations over follow-up. Children receiving artesunate had the greatest reduction in mortality and benefit in behavioral outcomes and had reduced inflammation at 1-month follow-up compared to children treated with quinine.

CONCLUSIONS

Treatment of severe malaria with artemisinin derivatives, particularly artesunate, results in reduced in-hospital mortality and neurologic deficits in children of all ages, reduced inflammation following recovery, and better long-term behavioral outcomes. These findings suggest artesunate has long-term beneficial effects in children surviving severe malaria.

Activation of GPR37 in macrophages confers protection against infection-induced sepsis and pain-like behaviour in mice

GPR37 was discovered more than two decades ago, but its biological functions remain poorly understood. Here we report a protective role of GPR37 in multiple models of infection and sepsis. Mice lacking Gpr37 exhibited increased death and/or hypothermia following challenge by lipopolysaccharide (LPS), Listeria bacteria, and the mouse malaria parasite Plasmodium berghei. Sepsis induced by LPS and Listeria in wild-type mice is protected by artesunate (ARU) and neuroprotectin D1 (NPD1), but the protective actions of these agents are lost in Gpr37^−/− mice. Notably, we found that ARU binds to GPR37 in macrophages and promotes phagocytosis and clearance of pathogens. Moreover, ablation of macrophages potentiated infection, sepsis, and their sequelae, whereas adoptive transfer of NPD1- or ARU-primed macrophages reduced infection, sepsis, and pain-like behaviors. Our findings reveal physiological actions of ARU in host cells by activating macrophages and suggest that GPR37 agonists may help to treat sepsis, bacterial infections, and malaria.

GPR37 is expressed in macrophages, and has been implicated in resolution of inflammatory pain. Here the authors show that GPR37 can modulate sepsis in several animal models.

Artesunate alleviates diabetic retinopathy by activating autophagy via the regulation of AMPK/SIRT1 pathway

CONTEXT

Artesunate (ART), an antimalarial drug, possesses the ability to induce autophagy and exhibits a protective effect on diabetes.

OBJECTIVE

This study aimed to evaluate the effects of ART on diabetic retinopathy (DR) and to explore the underlying mechanisms.

METHODS

Rats with streptozotocin-induced DR were given intravitreal injection of ART.

RESULTS

ART administration inhibited the increase in retinal thickness and prevented blood-retinal barrier in diabetic rats. Further, vascular leukocyte adherence, microglial activation, inflammatory cytokine, and ROS production in the retinas of diabetic rats were also inhibited by ART. Additionally, ART enhanced autophagy in the retinas of diabetic rats as demonstrated by up-regulated Beclin-1 expression and LC3II/I ratio and down-regulated p62. ART also activated AMP-activated protein kinase (AMPK)/sensor class III histone deacetylase sirtuin 1 (SIRT1) pathway.

CONCLUSIONS

ART, as an autophagy activator, has therapeutic potential in DR treatment.

Effect of Artesunate Combined With Fractional CO2 Laser on the Hypertrophic Scar in a Rabbit Model

BACKGROUND AND OBJECTIVES

Hypertrophic scar (HS), a common complication in wound healing, is characterized by the disarrangement of collagen, fibers, and extracellular matrix. Artesunate (ART) can inhibit the abnormal formation of fibroblasts and collagens. Fractional CO2 laser (FCO2 L) can facilitate tissue remodeling and the absorption of drugs into ablative microthermal columns in HS. So far, no research has investigated the efficacy of ART combined with an FCO2 L in treating HS. To investigate the theoretical basis and clinical significance of this combination, we established a rabbit model of HS to observe the change in the expression of transforming growth factor β1 (TGF-β1) and proliferating cell nuclear antigen (PCNA).

STUDY DESIGN/MATERIALS AND METHODS

Forty New Zealand white rabbits were randomly divided into four groups: control group, ART group, FCO2 L group, and ART + FCO2 L (combination) group. Four wounds were surgically established in the ear of each rabbit and allowed to develop into HS. ART (20 μL/cm2 ) was injected in ART and combination groups, and FCO2 L (combo mode, deep energy:10m J, super energy: 50 mJ) in FCO2 L and combination groups on the 28th day after HS occurred. Three rounds of treatment were applied (once every 14 days). HS samples were measured by hematoxylin and eosin staining, Van Gieson staining, immunohistochemistry, and Western blot analysis on the 70th day.

RESULTS

The morphological and histopathological changes in HS were significant. HSs were smoother and smaller and the collagen fibers were thinner and less disordered in the combination group than those in ART and FCO2 L groups. Meanwhile, the hypertrophic index (HI), fiber density (NA), and collagen fiber content (AA) were lower in the combination group (1.54 ± 0.15, 3.30 ± 0.22, 30.37 ± 1.41%) than in the ART group (2.51 ± 0.22, 4.69 ± 0.16, 44.68 ± 2.30%) and FCO2 L group (1.99 ± 0.14, 4.13 ± 0.12, 37.74 ± 1.38%) (P < 0.01). Additionally, the expressions of TGF-β1 and PCNA protein were suppressed in the ART group (0.30 ± 0.03, 0.25 ± 0.03) and FCO2 L group (0.35 ± 0.03, 0.32 ± 0.05), and the suppression was more significant in the combination group(0.07 ± 0.02, 0.07 ± 0.02) (P < 0.01).

CONCLUSIONS

The combination of ART and FCO2 L can effectively reduce HS in the rabbit model. This is the first report about this combination in the treatment of HS. A novel treatment is expected to be based on our findings. Lasers Surg. Med. © 2021 Wiley Periodicals LLC.

Could Artesunate Have a Positive Effect on the Neurological Complications Related to Infection When It Is Used in the Treatment of COVID-19?

Artesunate is a safe noncytotoxic drug with low side effects which is used in the treatment of chloroquine-resistant malaria. In addition to being an antimalarial drug, artesunate also has immunomodulatory, anticarcinogenic, and antiviral activity. There are in vivo and in vitro studies reporting that artesunate may have a positive effect on the treatment of COVID-19. Artesunate may be effective based on its effect on the anti-inflammatory activity, chloroquine-like endocytosis inhibition mechanism, and nuclear factor kappa B (NF-κB) signal pathway. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may cause neurological complications in addition to targeting the respiratory system. In this study, we have discussed the possible neuroprotective action mechanisms of artesunate. We think that systemic and intranasal topical artesunate administration may have a positive effect on neurological complications resulting from COVID-19.

Diarrhea in Children with Plasmodium falciparum Malaria: A Case-Control Study on the Prevalence and Response to Antimalarial Treatment

The role of Plasmodium in the etiology of acute diarrhea in developing countries remains controversial, and gastrointestinal (GI) symptoms are inconsistently reported in malaria. In this observational case-control study, we investigated the prevalence and risk factors for GI symptoms in hospitalized malarious children aged 1 month to 5 years in northern Uganda. Children with a diagnosis of Plasmodium falciparum malaria were enrolled as cases, and feverish children in whom malaria was excluded were enrolled as controls. Among 451 malarious children, 46.1% had GI symptoms at admission. Compared with controls, the frequency of diarrhea (24.8% versus 11.2%, P < 0.001) and vomiting (35.5% versus 17.5%, P < 0.001) was significantly higher in children with malaria, who had a higher chance of showing either vomiting (odds ratio [OR]: 3.22; 95% CI: 2.14-4.91) or diarrhea (OR: 3.14; 95% CI: 1.99-5.07) at hospital admission. A subgroup analysis performed in children with severe malaria, severe anemia, or high-grade fever confirmed these results. Diarrhea was more frequent in infants and children younger than 3 years than in older children. The analysis of 71 malarious children with diarrhea who received intravenous artesunate showed that the symptom resolved within the first 24 hours since the beginning of the treatment in 85.9% of cases. The 3-fold higher prevalence of diarrhea and vomiting in malarious children compared with febrile controls may provide rationale for incorporating malaria testing in the symptom-guided diagnostic approach of the young child with diarrhea and vomiting in malaria-endemic settings.

Aberrant Dopamine Receptor Signaling Plays Critical Role in the Impairment of Striatal Neurons in Experimental Cerebral Malaria

One-fourth survivors of cerebral malaria (CM) retain long-term cognitive and behavioral deficits. Structural abnormalities in striatum are reported in 80% of children with CM. Dopamine receptors (D1 and D2) are widely expressed in striatal medium spiny neurons (MSNs) that regulate critical physiological functions related to behavior and cognition. Dysregulation of dopamine receptors alters the expression of downstream proteins such as dopamine- and cAMP-regulated phosphoprotein (DARPP), Ca²⁺/calmodulin-dependent protein kinase II alpha (CaMKIIα), and p25/cyclin-dependent kinase 5 (cdk5). However, the role of dopamine receptor signaling dysfunction on the outcome of striatal neuron degeneration is unknown underlying the pathophysiology of CM. Using experimental CM (ECM), the present study attempted to understand the role of aberrant dopamine receptor signaling and its possible relation in causing MSNs morphological impairment. The effect of antimalarial drug artemether (ARM) rescue therapy was also assessed after ECM on the outcome of dopamine receptors downstream signaling. ECM was induced in C57BL/6 mice (male and female) infecting with Plasmodium berghei ANKA (PbA) parasite that reiterates the clinical setting of CM. We demonstrated that ECM caused a significant increase in the expression of D1, D2 receptors, phosphorylated DARPP, p25, cdk5, CaMKIIα, and D1-D2 heteromers. A substantial increase in neuronal damage observed in the dorsolateral striatum region of ECM brains (particularly in MSNs) as revealed by increased Fluoro-Jade C staining, reduced dendritic spine density, and impaired dendritic arborization with varicosities. While the ARM rescue therapy significantly altered the effects of ECM induced dopamine receptor signaling dysfunction and neurodegeneration. Overall, our data suggest that dysregulation of dopamine receptor signaling plays an important role in the degeneration of MSNs, and the ARM rescue therapy might provide better insights to develop effective therapeutic strategies for CM.

Artesunate interacts with the vitamin D receptor to reverse sepsis-induced immunosuppression in a mouse model via enhancing autophagy

BACKGROUND AND PURPOSE

Immunosuppression is the predominant cause of mortality for sepsis because of failure to eradicate pathogens. No effective and specific drugs capable of reversing immunosuppression are clinically available. Evidences implicate the involvement of the vitamin D receptor (NR1I1) in sepsis-induced immunosuppression. The anti-malarial artesunate was investigated to determine action on sepsis-induced immunosuppression.

EXPERIMENTAL APPROACH

The effect of artesunate on sepsis-induced immunosuppression was investigated in mice and human and mice cell lines. Bioinformatics predicted vitamin D receptor as a candidate target for artesunate, which was then identified using PCR and immunoblotting. Vdr, Atg16l1 and NF-κB p65 were modified to investigate artesunate 's effect on pro-inflammatory cytokines release, bacterial clearance and autophagy activities in sepsis-induced immunosuppression.

KEY RESULTS

Artesunate significantly reduced the mortality of caecal ligation and puncture (CLP)-induced sepsis immunosuppression mice challenged with Pseudomonas aeruginosa and enhanced pro-inflammatory cytokine release and bacterial clearance to reverse sepsis-induced immunosuppression in vivo and in vitro. Mechanistically, artesunate interacted with vitamin D receptor, inhibiting its nuclear translocation, which influenced ATG16L1 transcription and subsequent autophagy activity. Artesunate inhibited the physical interaction between vitamin D receptor and NF-κB p65 in LPS-tolerant macrophages and then promoted the nuclear translocation of NF-κB p65, which activated the transcription of NF-κB p65 target genes such as pro-inflammatory cytokines.

CONCLUSION AND IMPLICATIONS

Our findings provide evidence that artesunate interacted with vitamin D receptor to reverse sepsis-induced immunosuppression in an autophagy and NF-κB-dependent manner, highlighting a novel approach for sepsis treatment and drug repurposing of artesunate has a bidirectional immunomodulator.

Effect of Artesunate on Leishmania Amazonesis Induced Neuroinflammation and Nociceptive Behavior in Male Balb/C Mice

Simple Summary

Leishmaniasis is a multisystemic zoonotic disease with several symptoms, and treating this disease is a great challenge for veterinary medicine. Artemisinin derivatives are currently the most widely used drugs for the treatment of malaria, especially for their excellent safety profile and low cost. Artesunate is a more stable derivative of its precursor, artemisin, and has been shown to be a pluripotent agent with different pharmacological actions. In this study, we evaluated the role of neuroinflammation in leishmaniasis and its correlation with pain and sickness behavior, and the anti-inflammatory and neuroprotective effects of artesunate in a murine model of Leishmania amazonensis infection in BALB/c mice. The results from this study indicate that artesunate is a good candidate for treatment and/or as an adjuvant in anti- leishmaniasis therapy, and for preventing and alleviating leishmaniasis-induced pain and neuroinflammation.

Abstract

Background: Leishmaniasis is a multisystemic zoonotic disease with several symptoms, including neurological disorders. Leishmaniasis is accompanied by an increase in nociceptive behaviors, linked to the presence of a chronic inflammatory state, in both peripheral tissue and the central nervous system. Artesunate is a more stable derivative of its precursor artemisin and has been shown to be a pluripotent agent with different pharmacological actions. Methods: In this study, we investigated the effects of artesunate in Leishmaniaamazonensi- infected BALB/c mice, evaluating its effectiveness in reducing inflammation, neuroinflammation, and nociceptive and sickness behaviors. Results: Our results demonstrate a significant increase in pain sensitivity and sickness behaviors after L. amazonensis infection. Moreover, the infection induced a significant increase in inflammatory response at both the paw and spinal cord level. Treatment with artesunate was able to induce a significant decrease in tissue inflammation and neuroinflammation and thus induce a significant decrease in pain sensitivity and sickness behaviors. Conclusions: The results from this study indicate that artesunate is a good candidate for treatment and/or as an adjuvant in leishmanicidal therapy, and to prevent and alleviate leishmaniasis-induced pain and neuroinflammation and thereby improve the quality of life of leishmaniasis patients.

Effect of artesunate and relation with TGF-β1 and SMAD3 signaling on experimental hypertrophic scar model in rabbit ear

Artesunate (ART) is the derivative of artemisinin isolated from the traditional Chinese medicine qinghao. Although several studies reported the efficiency of artesunate in the treatment of malaria, inhibiting fibroblasts and collagen synthesis, the association between artesunate and scar formation is unclear. The research was designed to study the significance of artesunate (ART) on the expression of transforming growth factor (TGF-β1) and small mother against decapentaplegic (SMAD3) in rabbit's ear hypertrophic scar model. Twenty-four New Zealand white rabbits were randomly divided into six groups: control group, matrix group, low-concentration artesunate group (0.48%), medium-concentration artesunate group (0.96%), high-concentration artesunate group (1.92%) and silicone gel group. Punched defects were established on each rabbit’s ear which resulted in a hypertrophic scar. On the 28th day, topical artesunate creams were applied twice a day except on the control group. On the 56th day, scar samples were collected for histopathology and immunoassay. Hematoxylin and eosin staining, Van Gieson staining, immunohistochemistry and Western blot analysis were done. Amongst the six groups, findings showed that the medium-concentration artesunate group (0.92%) efficiently decreased hypertrophic scar formation and significantly reduced fibroblasts and collagen synthesis. The results had also shown a decrease in the expression of transforming growth factor (TGF-β1) and declined small signal mother against decapentaplegic (Smad3). The overall study shows efficacy and mechanism of artesunate. It concluded that the medium concentration of artesunate (0.92%) could be an effective therapeutic agent for hypertrophic scars.

TRPV1 Contributes to Cerebral Malaria Severity and Mortality by Regulating Brain Inflammation

Transient receptor potential vanilloid 1 (TRPV1) is a Ca⁺²-permeable channel expressed on neuronal and nonneuronal cells, known as an oxidative stress sensor. It plays a protective role in bacterial infection, and recent findings indicate that this receptor modulates monocyte populations in mice with malaria; however, its role in cerebral malaria progression and outcome is unclear. By using TRPV1 wild-type (WT) and knockout (KO) mice, the importance of TRPV1 to this cerebral syndrome was investigated. Infection with Plasmodium berghei ANKA decreased TRPV1 expression in the brain. Mice lacking TRPV1 were protected against Plasmodium-induced mortality and morbidity, a response that was associated with less cerebral swelling, modulation of the brain expression of endothelial tight-junction markers (junctional adhesion molecule A and claudin-5), increased oxidative stress (via inhibition of catalase activity and increased levels of H₂O₂, nitrotyrosine, and carbonyl residues), and diminished production of cytokines. Plasmodium load was not significantly affected by TRPV1 ablation. Repeated subcutaneous administration of the selective TRPV1 antagonist SB366791 after malaria induction increased TRPV1 expression in the brain tissue and enhanced mouse survival. These data indicate that TRPV1 channels contribute to the development and outcome of cerebral malaria.

Sex-Associated Differential mRNA Expression of Cytokines and Its Regulation by Sex Steroids in Different Brain Regions in a Plasmodium berghei ANKA Model of Cerebral Malaria

Cerebral malaria (CM) is the major complication associated with death in malaria patients, and its pathogenesis is associated with excessive proinflammatory cytokine production. Notably, the severity and mortality of natural infections with Plasmodium are higher in males than females, suggesting that sexual hormones influence both the pathogenesis of and immune response in CM. However, no studies on inflammation mediators in the brains of both sexes have been reported. In this work, the mRNA expression levels of the proinflammatory cytokines IL-1β, IFN-γ, TNF-α, and IL-2 were measured in the preoptic area, hypothalamus, hippocampus, olfactory bulb, frontal cortex, and lateral cortex regions of gonadectomized female and male CBA/Ca mice infected with P. berghei ANKA (a recognized experimental CM model). Our findings demonstrate that both infection with P. berghei ANKA and gonadectomy trigger a cerebral sex dimorphic mRNA expression pattern of the cytokines IL-1β, TNF-α, IFN-γ, and IL-2. This dimorphic cytokine pattern was different in each brain region analysed. In most cases, infected males exhibited higher mRNA expression levels than females, suggesting that sexual hormones differentially regulate the mRNA expression of proinflammatory cytokines in the brain and the potential use of gonadal steroids or their derivates in the immunomodulation of cerebral malaria.

Neuroprotective Effect of Artesunate in Experimental Model of Traumatic Brain Injury

Traumatic brain injuries (TBI) are an important public health challenge. In addition, subsequent events at TBI can compromise the quality of life of these patients. In fact, TBI is associated with several complications for both long and short term, some evidence shows how TBI is associated with a decline in cognitive functions such as the risk of developing dementia, cerebral atrophy, and Parkinson disease. After the direct damage from TBI, a key role in TBI injury is played by the inflammatory response and oxidative stress, that contributes to tissue damage and to neurodegenerative processes, typical of secondary injury, after TBI. Given the complex series of events that are involved after TBI injury, a multitarget pharmacological approach is needed. Artesunate is a more stable derivative of its precursor artemisin, a sesquiterpene lactone obtained from a Chinese plant Artemisia annua, a plant used for centuries in traditional Chinese medicine. artesunate has been shown to be a pluripotent agent with different pharmacological actions. therefore, in this experimental model of TBI we evaluated whether the treatment with artesunate at the dose of 30 mg\Kg, had an efficacy in reducing the neuroinflammatory process after TBI injury, and in inhibiting the NLRP3 inflammasome pathway, which plays a key role in the inflammatory process. We also assessed whether treatment with artesunate was able to exert a neuroprotective action by modulating the release of neurotrophic factors. our results show that artesunate was able to reduce the TBI-induced lesion, it also showed an anti-inflammatory action through the inhibition of Nf-kb, release of proinflammatory cytokines IL-1β and TNF-α and through the inhibition NLRP3 inflammasome complex, furthermore was able to reduce the activation of astrocytes and microglia (GFAP, Iba-1). Finally, our results show that the protective effects of artesunate also occur through the modulation of neurotrophic factors (BDNF, GDNF, NT-3) that play a key role in neuronal survival.

Doxycycline inhibits experimental cerebral malaria by reducing inflammatory immune reactions and tissue-degrading mediators

Malaria ranks among the most important infectious diseases worldwide and affects mostly people living in tropical countries. Mechanisms involved in disease progression are still not fully understood and specific treatments that might interfere with cerebral malaria (CM) are limited. Here we show that administration of doxycycline (DOX) prevented experimental CM (ECM) in Plasmodium berghei ANKA (PbA)-infected C57BL/6 wildtype (WT) mice in an IL-10-independent manner. DOX-treated mice showed an intact blood-brain barrier (BBB) and attenuated brain inflammation. Importantly, if WT mice were infected with a 20-fold increased parasite load, they could be still protected from ECM if they received DOX from day 4-6 post infection, despite similar parasitemia compared to control-infected mice that did not receive DOX and developed ECM. Infiltration of T cells and cytotoxic responses were reduced in brains of DOX-treated mice. Analysis of brain tissue by RNA-array revealed reduced expression of chemokines and tumour necrosis factor (TNF) in brains of DOX-treated mice. Furthermore, DOX-administration resulted in brains of the mice in reduced expression of matrix metalloproteinase 2 (MMP2) and granzyme B, which are both factors associated with ECM pathology. Systemic interferon gamma production was reduced and activated peripheral T cells accumulated in the spleen in DOX-treated mice. Our results suggest that DOX targeted inflammatory processes in the central nervous system (CNS) and prevented ECM by impaired brain access of effector T cells in addition to its anti-parasitic effect, thereby expanding the understanding of molecular events that underlie DOX-mediated therapeutic interventions.

Effects of Artesunate on the Expressions of Insulin-Like Growth Factor-1, Osteopontin and C-Telopeptides of Type II Collagen in a Rat Model of Osteoarthritis

Objective: The study aims to explore the effects of artesunate on insulin-like growth factor-1 (IGF-1), Osteopontin (OPN), and C-telopeptides of type II collagen (CTX-II) in serum, synovial fluid (SF), and cartilage tissues of rats with osteoarthritis (OA). Methods: OA models were established. Normal model, artesunate, and Viatril-S groups (20 rats respectively) were set. Enzyme-linked immunosorbent assay, IHC staining, and quantitative real-time polymerase chain reaction were conducted to calculate IGF-1, OPN, and CTX-II levels in serum, SF, and cartilage tissues of rats. The pathological changes in cartilage tissues were evaluated with Mankin score and Hematoxylin-Eosin staining. Results: Compared with the normal group, the model group showed increased IGF-1 level; decreased OPN, CTX-II levels in the serum and SF; and contrary results were seen in the cartilage tissues. A gradual ascending IGF-1 level and descending OPN and CTX-II levels existed in the serum and SF in the artesunate and Viatril-S groups after 2 weeks. The model group showed the most obvious pathological changes and highest Mankin score compared with the other groups. Higher IGF-1 level and lower OPN, CTX-II levels were exhibited in the cartilage tissue in the artesunate and Viatril-S groups but not in the model group. Conclusion: Artesunate and Viatril-S inhibit OA development by elevating IGF-1 level and reducing OPN and CTX-II levels.

Suppressor of cytokine signaling 2 modulates the immune response profile and development of experimental cerebral malaria

Plasmodium falciparum infection results in severe malaria in humans, affecting various organs, including the liver, spleen and brain, and resulting in high morbidity and mortality. The Plasmodium berghei ANKA (PbA) infection in mice closely recapitulates many aspects of human cerebral malaria (CM); thus, this model has been used to investigate the pathogenesis of CM. Suppressor of cytokine signaling 2 (SOCS2), an intracellular protein induced by cytokines and hormones, modulates the immune response, neural development, neurogenesis and neurotrophic pathways. However, the role of SOCS2 during CM remains unknown. SOCS2 knockout (SOCS2(-/-)) mice infected with PbA show an initial resistance to infection with reduced parasitemia and production of TNF, TGF-β, IL-12 and IL-17 in the brain. Interestingly, in the late phase of infection, SOCS2(-/-) mice display increased parasitemia and reduced Treg cell infiltration, associated with enhanced levels of Th1 and Th17 cells and related cytokines IL-17, IL-6, and TGF-β in the brain. A significant reduction in protective neurotrophic factors, such as glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF), was also observed. Moreover, the molecular alterations in the brain of infected SOCS2(-/-) mice were associated with anxiety-related behaviors and cognition impairment. Mechanistically, these results revealed enhanced nitric oxide (NO) production in PbA-infected SOCS2(-/-) mice, and the inhibition of NO synthesis through l-NAME led to a marked decrease in survival, the disruption of parasitemia control and more pronounced anxiety-like behavior. Treatment with l-NAME also shifted the levels of Th1, Th7 and Treg cells in the brains of infected SOCS2(-/-) mice to the background levels observed in infected WT, with remarkable exception of increased CD8(+)IFN(+) T cells and inflammatory monocytes. These results indicate that SOCS2 plays a dual role during PbA infection, being detrimental in the control of the parasite replication but crucial in the regulation of the immune response and production of neurotrophic factors. Here, we provided strong evidence of a critical relationship between SOCS2 and NO in the orchestration of the immune response and development of CM during PbA infection.

Cerebral malaria--clinical manifestations and pathogenesis

One of the most common central nervous system diseases in tropical countries is cerebral malaria (CM). Malaria is a common protozoan infection that is responsible for enormous worldwide mortality and economic burden on the society. Episodes of Plasmodium falciparum (Pf) caused CM may be lethal, while survivors are likely to suffer from persistent debilitating neurological deficits, especially common in children. In this review article, we have summarized the various symptoms and manifestations of CM in children and adults, and entailed the molecular basis of the disease. We have also emphasized how pathogenesis of the disease is effected by the parasite and host responses including blood brain barrier (BBB) disruption, endothelial cell activation and apoptosis, nitric oxide bioavailability, platelet activation and apoptosis, and neuroinflammation. Based on a few recent studies carried out in experimental mouse malaria models, we propose a basis for the neurological deficits and sequelae observed in human cerebral malaria, and summarize how existing drugs may improve prognosis in affected individuals.

Artesunate protects pancreatic beta cells against cytokine-induced damage via SIRT1 inhibiting NF-κB activation

AIM

Artesunate (ART) has been known as the most effective and safe reagents to treat malaria for many years. In this study, we explored whether ART could protect pancreatic beta-cell against cytokine-induced damage.

MATERIALS AND METHODS

The production of nitrite (NO) was detected with the Griess Assay Kit. SIRT1 and inducible nitric oxide synthase (iNOS) expression were determined with Western blot. The transcriptional activity of NF-κB was evaluated by luciferase reporter assay. The expression of Sirt1 was silenced by RNA interference. Glucose-stimulated insulin secretion (GSIS) and potassium-stimulated insulin secretion (KSIS) assays were performed to measure the effect of ART on pancreatic beta-cells' function. The effect of ART on beta-cells apoptosis was evaluated by using Hochest/PI staining and TUNEL assay.

RESULTS

ART enhanced GSIS (KSIS) and reduced apoptosis of pancreatic beta-cells induced by IL-1β. Further study showed that ART inhibited IL-1β-induced increase of NF-κB activity, iNOS expression, and NO production. Moreover, ART up-regulated SIRT1 expression in INS-1 cells and islets exposed to IL-1β. Inhibition of SIRT1 expression could partially abolished the inhibitory effect of ART on NF-κB activity in IL-1β-treated beta-cells. More importantly, the protective effect of ART on cytokine-induced damage was reversed by silencing SIRT1 expression.

CONCLUSIONS

ART can elicit a protective effect on beta-cells exposed to IL-1β by stimulating SIRT1 expression, which resulted in the decrease of NF-κB activity, iNOS expression, and NO production. Hence, ART might be an effective drug for diabetes.

The HFE genotype and a formulated diet controlling for iron status attenuate experimental cerebral malaria in mice

Plasmodium falciparum infects approximately 500million individuals each year. A small but significant number of infections lead to complications such as cerebral malaria. Cerebral malaria is associated with myelin damage and neurological deficits in survivors, and iron status is thought to impact the outcome of infection. We evaluated whether a mouse model of experimental cerebral malaria with Plasmodium berghei ANKA strain was altered by dietary iron deficiency or genetic iron overload (H67D HFE). We found that H67D mice had increased survival over H67H (wild type) mice. Moreover, a specifically designed formulation diet increased survival regardless of whether the diet was iron deficient or iron adequate. To determine potential mechanisms underlying demyelination in experimental cerebral malaria, we measured Semaphorin4A (Sema4A) protein levels in the brain because we found it is cytotoxic to oligodendrocytes. Sema4A was increased in wild type mice that developed experimental cerebral malaria while consuming standard rodent chow, consistent with a decrease in myelin basic protein, an indicator of myelin integrity. The brains of iron deficient and H67D mice had lower levels of Sema4A. Myelin basic protein was decreased in brains of mice fed the iron deficient diet as has been previously reported. We also examined erythropoietin, which is under consideration for treatment of cerebral malaria, and IL-6, which is known to increase during infection. We found that plasma erythropoietin was elevated and IL-6 was low in H67D mice and in the mice fed the formulation diets. These data reveal a paradigm-shifting concept that maintaining iron status may not increase the mortality associated with malaria and provide a dietary strategy for further examination. Moreover, the data provide clues for exploring the mechanism to limit the co-morbidity associated with experimental cerebral malaria that appears to include decreased Sema4A in brain as well as elevated erythropoietin and lower IL-6 in plasma.

Effects of artesunate against Trypanosma cruzi

Therapy against Trypanosma cruzi relies on only two chemically related nitro-derivative drugs, benznidazole and nifurtimox, both limited by poor efficacy and toxicity. It is suspected that with prolonged usage of these drugs, resistant parasites will be selected, which results in risk for treatment failure over the time. Herein, we studied the in vitro activity of artesunate, the most effective drug to treat severe P. falciparum and chloroquine-resistant P. vivax, on three strains of T. cruzi originated in different regions of Latin America (Argentina, Nicaragua and Brazil). The results of these assays showed that artesunate inhibits multiplication of epimastigotes (IC50 = 50, 6.10 and 23 µM, respectively) and intracellular amastigotes (IC50 = 15, 0.12 and 6.90 µM, respectively), indicating that it represents a potent anti-T. cruzi compound in terms of inhibiting parasite multiplication in vitro. We then tested the effect of artesunate in Balb/c mice infected with Brazil strain and found that it failed to cure the infection, suggesting that the drug may be unsuitable for in vivo treatment. When infected mice were treated with high doses AS + BZ, the outcome of infection was similar to that observed in mice treated with BZ alone. Nevertheless, understanding of structure-activity relationship of artesunate might lead to the development of new and effective drugs against T. cruzi.

Cannabidiol increases survival and promotes rescue of cognitive function in a murine model of cerebral malaria

Cerebral malaria (CM) is a severe complication resulting from Plasmodium falciparum infection that might cause permanent neurological deficits. Cannabidiol (CBD) is a nonpsychotomimetic compound of Cannabis sativa with neuroprotective properties. In the present work, we evaluated the effects of CBD in a murine model of CM. Female mice were infected with Plasmodium berghei ANKA (PbA) and treated with CBD (30mg/kg/day - 3 or 7days i.p.) or vehicle. On 5th day-post-infection (dpi), at the peak of the disease), animals were treated with single or repeated doses of Artesunate, an antimalarial drug. All groups were tested for memory impairment (Novel Object Recognition or Morris Water Maze) and anxiety-like behaviors (Open field or elevated plus maze test) in different stages of the disease (at the peak or after the complete clearance of the disease). Th1/Th2 cytokines and neurotrophins (brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF)) were measured in the prefrontal cortex and hippocampus of experimental groups. PbA-infected mice displayed memory deficits and exhibited increase in anxiety-like behaviors on the 5dpi or after the clearance of the parasitemia, effects prevented by CBD treatment. On 5dpi, TNF-α and IL-6 increased in the hippocampus, while only IL-6 increased in the prefrontal cortex. CBD treatment resulted in an increase in BDNF expression in the hippocampus and decreased levels of proinflammatory cytokines in the hippocampus (TNF-α) and prefrontal cortex (IL-6). Our results indicate that CBD exhibits neuroprotective effects in CM model and might be useful as an adjunctive therapy to prevent neurological symptoms following this disease.

Evidence for the contribution of adult neurogenesis and hippocampal cell death in experimental cerebral malaria cognitive outcome

Cognitive dysfunction is a major sign of cerebral malaria (CM). However, the underlying mechanisms of CM cognitive outcome remain poorly understood. A body of evidence suggests that adult neurogenesis may play a role in learning and memory processes. It has also been reported that these phenomena can be regulated by the immune system. We hypothesized that memory dysfunction in CM results from hippocampal neurogenesis impairment mediated by the deregulated immune response during the acute phase of CM. C57Bl/6 mice were infected with Plasmodium berghei ANKA (PbA) strain, using a standardized inoculation of 10(6) parasitized erythrocytes. Long-term working memory was evaluated using the novel object recognition test. The mRNA expression of brain-derived neurotrophic factor (BDNF), tropomyosin-receptor-kinase (TRK-B) and nerve growth factor (NGF) in the frontal cortex and hippocampus was estimated by real-time polymerase chain reaction (PCR). The protein levels of cytokine interleukin-2 (IL-2), IL-4, IL-6, IL-10, interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and CCL11 and neurotrophins BDNF and NGF were determined using a cytometric bead array (CBA) kit or enzyme-linked immunosorbent assay. Cell viability in the hippocampus was analyzed by Confocal Microscopy. Neurogenesis in the dentate gyrus was determined through quantification of doublecortin (DCX) positive cells. PbA-infected mice presented working memory impairment on day 5 post-infection. At this same time point, CM mice exhibited a decrease in DCX-positive cells in the dentate gyrus in parallel with increased cell death and elevated inflammatory cytokines (IL-6, TNF-α, IFN-γ and CCL11) in the hippocampus and frontal cortex. A significant reduction of BDNF mRNA expression was also found. IL-6 and TNF-α correlated negatively with BDNF and NGF levels in the hippocampus of CM mice. In summary, we provide further evidence that neuroinflammation following PbA-infection influences neurotrophin expression, impairs adult hippocampal neurogenesis and increases hippocampal cell death in association with memory impairment following CM course. The current study identified potential mediators of memory impairment in CM.

Single episode of mild murine malaria induces neuroinflammation, alters microglial profile, impairs adult neurogenesis, and causes deficits in social and anxiety-like behavior

Cerebral malaria is associated with cerebrovascular damage and neurological sequelae. However, the neurological consequences of uncomplicated malaria, the most prevalent form of the disease, remain uninvestigated. Here, using a mild malaria model, we show that a single Plasmodium chabaudi adami infection in adult mice induces neuroinflammation, neurogenic, and behavioral changes in the absence of a blood-brain barrier breach. Using cytokine arrays we show that the infection induces differential serum and brain cytokine profiles, both at peak parasitemia and 15days post-parasite clearance. At the peak of infection, along with the serum, the brain also exhibited a definitive pro-inflammatory cytokine profile, and gene expression analysis revealed that pro-inflammatory cytokines were also produced locally in the hippocampus, an adult neurogenic niche. Hippocampal microglia numbers were enhanced, and we noted a shift to an activated profile at this time point, accompanied by a striking redistribution of the microglia to the subgranular zone adjacent to hippocampal neuronal progenitors. In the hippocampus, a distinct decline in progenitor turnover and survival was observed at peak parasitemia, accompanied by a shift from neuronal to glial fate specification. Studies in transgenic Nestin-GFP reporter mice demonstrated a decline in the Nestin-GFP(+)/GFAP(+) quiescent neural stem cell pool at peak parasitemia. Although these cellular changes reverted to normal 15days post-parasite clearance, specific brain cytokines continued to exhibit dysregulation. Behavioral analysis revealed selective deficits in social and anxiety-like behaviors, with no change observed in locomotor, cognitive, and depression-like behaviors, with a return to baseline at recovery. Collectively, these findings indicate that even a single episode of mild malaria results in alterations of the brain cytokine profile, causes specific behavioral dysfunction, is accompanied by hippocampal microglial activation and redistribution, and a definitive, but transient, suppression of adult hippocampal neurogenesis.