Surface antigens in Plasmodium falciparum malaria : PfEMP1 and SURFIN4.2

Plasmodium falciparum malaria is an infectious disease that on despite of the ongoing eradication efforts is still endemic in more than 100 countries, sometimes causing severe disease that leads to the death of around half a million people per year. Malaria pathology is tightly associated with the parasite cycle inside the human red blood cells (RBCs). Central to this cycle is the initial invasion by the merozoite and the extensive RBC modifications induced by the parasite, transporting proteins to the RBC cytoplasm and membrane. The P. falciparum Erythrocyte Membrane Protein 1 (PfEMP1) transported to the surface of the parasitized RBC (pRBC) and the surface-associated interspersed protein 4.2 (SURFIN4.2) present both at the pRBC surface as well as at the merozoite apex and surface, are the major focus of this thesis. PfEMP1 is the major surface antigen and mediates rosetting (binding of parasitized RBCs (pRBCs) to two or more RBCs), a parasite phenotype associated with the development of severe disease. The most N-terminal segment of this protein (the NTSDBL1α domain) has been identified as the ligand for rosetting and naturally acquired antibodies targeting this particular protein protect against severe disease development. In this study we wanted to address the specific regions in PfEMP1 and in other protein targets recognized by rosette-disrupting antibodies (generated upon immunization with recombinant PfEMP1 or naturally acquired during P. falciparum infection). We also wanted to explore other functional roles of these antibodies. A panel of antibodies (monoclonal and polyclonal) against rosette-mediating NTS-DBL1α domains was produced by animal immunization. The antibodies were analyzed with particular attention to their capacity to recognize the surface of the pRBC, disrupt the rosettes formed by homologous parasites and induce phagocytosis by monocytic cells. Additionally, the specific epitopes recognized by the majority of these antibodies were successfully mapped to a specific region of subdomain 3 (SD3) of the DBL1α domain, regardless of the parasite strain used. These results suggested this region as a major target of anti-rosetting antibodies. Most of these antibodies also induced opsonization for phagocytosis, a role that could be of great importance during pRBCs clearance in vivo. Interestingly, some of the antibodies with high opsonizing activity did not disrupt rosettes, indicating that other epitopes besides those involved in rosetting are exposed on the pRBC surface and are able to induce functional antibodies that could provide protection. The naturally acquired antibodies in sera from children living in a malaria endemic region were also investigated. The ability of these antibodies to recognize three parasite-derived surface proteins (PfEMP1, RIFIN-A and SURFIN4.2) was assessed. Different variables were also measured in the presence of these sera samples, including rosetting rate, surface reactivity and opsonization for phagocytosis on a rosetting model parasite grown in group O or group A RBCs. The data showed that the acquired immune response developed during natural infection could recognize the pRBC surface and more importantly could induce pRBC phagocytosis and in a few cases disrupt the rosettes formed by a heterologous parasite model. These activities however had limited access to the pRBCs inside a rosette formed with group A RBCs, where these cells act as a shield for the pRBCs, protecting it from antibodies’ recognition therefore impairing their effector function. This study also suggested that SURFIN4.2 previously identified at the pRBC surface could be involved in rosette formation, either as a direct ligand or as an accessory element for rosette strengthening. The suggestion of SURFIN4.2 as a possible mediator in rosetting prompted us to deepen the study of this protein, however, the initial results steered the approach to this protein from the rosetting phenomenon towards a more striking and understudied role of this protein during the invasion process. Using antibodies against the N-terminus, the protein was observed at the surface of the merozoite but more strikingly also in the neck of the rhoptries. The protein was shed into culture supernatant upon schizont rupture and was associated with GLURP (Glutamate Rich Protein) and RON-4 (Rhoptry Neck Protein 4) to form a complex we named SURGE (SURFIN4.2-RON-4-GLURP complEx). Importantly, SURFIN4.2 was detected at the apex of the merozoite during merozoite initial attachment and active invasion into the RBCs. The exact functional role of SURGE remains to be determined, but the presence of RON-4, a protein confined to the moving junction (MJ), strongly suggests a role in strengthening the stable contact between the merozoite apex and the RBC, possibly as and additional RBC adhesion molecule. Supporting the involvement of the protein complex during the invasion process, antibodies against the N-terminus of SURFIN4.2 partially inhibited invasion

Climate change impacts the economic development of low-income countries

Their livelihoods depend strongly on the weather, and relatively weak institutions limit their ability to cope, write David Castells-Quintana, Maria Lopez-Uribe and Tom McDermot

El papel del clima social y su relación con otras variables psicosociales en una muestra de personas privadas de libertad

El clima social tiene la base en las interacciones personales, representando la personalidad de un determinado ambiente, con posibilidades de influir en las conductas de los internos y del personal penitenciario. En este estudio se pretende analizar, en una muestra de 150 participantes, el grado y la relación del clima social con la participación social, sentido de comunidad, apoyo social y autoestima. Las personas internas perciben un negativo clima social (CIES), las puntuaciones se sitúan por debajo del 4 en una escala del 1 al 10. Se identifican las diferencias entre hombres y mujeres, entre módulos y entre los que reciben visitas o no.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Phagocytosis-inducing antibodies to Plasmodium falciparum upon immunization with a recombinant PfEMP1 NTS-DBL1α domain

Background: Individuals living in endemic areas gradually acquire natural immunity to clinical malaria, largely dependent on antibodies against parasite antigens. There are many studies indicating that the variant antigen PfEMP1 at the surface of the parasitized red blood cell (pRBC) is one of the major targets of the immune response. It is believed that antibodies against PfEMP1 confer protection by blocking sequestration (rosetting and cytoadherence), inducing antibody-dependent cellular-inhibitory effect and opsonizing pRBCs for phagocytosis. Methods: A recombinant NTS-DBL1α domain from a rosette-mediating PfEMP1 was expressed in Escherichia coli. The resulting protein was purified and used for immunization to generate polyclonal (goat) and monoclonal (mouse) antibodies. The antibodies’ ability to opsonize and induce phagocytosis in vitro was tested and contrasted with the presence of opsonizing antibodies naturally acquired during Plasmodium falciparum infection. Results: All antibodies recognized the recombinant antigen and the surface of live pRBCs, however, their capacity to opsonize the pRBCs for phagocytosis varied. The monoclonal antibodies isotyped as IgG2b did not induce phagocytosis, while those isotyped as IgG2a were in general very effective, inducing phagocytosis with similar levels as those naturally acquired during P. falciparum infection. These monoclonal antibodies displayed different patterns, some of them showing a concentration-dependent activity while others showed a prozone-like effect. The goat polyclonal antibodies were not able to induce phagocytosis. Conclusion: Immunization with an NTS-DBL1-α domain of PfEMP1 generates antibodies that not only have a biological role in rosette disruption but also effectively induce opsonization for phagocytosis of pRBCs with similar activity to naturally acquired antibodies from immune individuals living in a malaria endemic area. Some of the antibodies with high opsonizing activity were not able to disrupt rosettes, indicating that epitopes of the NTS-DBL1-α other than those involved in rosetting are exposed on the pRBC surface and are able to induce functional antibodies. The ability to induce phagocytosis largely depended on the antibody isotype and on the ability to recognize the surface of the pRBC regardless of the rosette-disrupting capacity

Climate change and the geographical and institutional drivers of economic development

This work was carried out under the Collaborative Adaptation Research Initiative in Africa and Asia (CARIAA), with financial support from the UK Government’s Department for International Development (DfID) and the International Development Research Centre (IDRC), Canada.Our review suggests that there are a potentially important set of dynamic interactions and feedback loops between institutions, climate (impacts and vulnerability) and development, which to date have been understudied. Understanding both the direct as well as the indirect effects of climate change is not only fundamental for the design of mitigation and adaptation strategies; whether by addressing the direct impacts of geographical factors, or by addressing their indirect effects on the socio-political environment, mitigation and adaptation strategies are also fundamental as key elements of broader development strategies. Moreover, as climate shocks disproportionally affect the poor, addressing climate-related risks is also a sound strategy in terms of addressing inequality and poverty reduction

A Sequence in Subdomain 2 of DBL1a of Plasmodium falciparum Erythrocyte Membrane Protein 1 Induces Strain Transcending Antibodies

Immunity to severe malaria is the first level of immunity acquired to Plasmodium falciparum. Antibodies to the variant antigen PfEMP1 (P. falciparum erythrocyte membrane protein 1) present at the surface of the parasitized red blood cell (pRBC) confer protection by blocking microvascular sequestration. Here we have generated antibodies to peptide sequences of subdomain 2 of PfEMP1-DBL1a previously identified to be associated with severe or mild malaria. A set of sera generated to the amino acid sequence KLQTLTLHQVREYWWALNRKEVWKA, containing the motif ALNRKE, stained the live pRBC. 50% of parasites tested (7/14) were positive both in flow cytometry and immunofluorescence assays with live pRBCs including both laboratory strains and in vitro adapted clinical isolates. Antibodies that reacted selectively with the sequence REYWWALNRKEVWKA in a 15-mer peptide array of DBL1a-domains were also found to react with the pRBC surface. By utilizing a peptide array to map the binding properties of the elicited anti-DBL1a antibodies, the amino acids WxxNRx were found essential for antibody binding. Complementary experiments using 135 degenerate RDSM peptide sequences obtained from 93 Ugandan patient-isolates showed that antibody binding occurred when the amino acids WxLNRKE/D were present in the peptide. The data suggests that the ALNRKE sequence motif, associated with severe malaria, induces strain-transcending antibodies that react with the pRBC surfac

Rosette-Disrupting Effect of an Anti-Plasmodial Compound for the Potential Treatment of Plasmodium falciparum Malaria Complications

The spread of artemisinin-resistant parasites could lead to higher incidence of patients with malaria complications. However, there are no current treatments that directly dislodge sequestered parasites from the microvasculature. We show that four common antiplasmodial drugs do not disperse rosettes (erythrocyte clusters formed by malaria parasites) and therefore develop a cell-based high-throughput assay to identify potential rosette-disrupting compounds. A pilot screen of 2693 compounds identified Malaria Box compound MMV006764 as a potential candidate. Although it reduced rosetting by a modest 20%, MMV006764 was validated to be similarly effective against both blood group O and A rosettes of three laboratory parasite lines. Coupled with its antiplasmodial activity and drug-likeness, MMV006764 represents the first small-molecule compound that disrupts rosetting and could potentially be used in a resource-limited setting to treat patients deteriorating rapidly from malaria complications. Such dual-action drugs that simultaneously restore microcirculation and reduce parasite load could significantly reduce malaria morbidity and mortality

OXY-SCORE: a new perspective for left ventricular hypertrophy diagnosis

Background: A recently developed global indicator of oxidative stress (OXY-SCORE), by combining individual plasma biomarkers of oxidative damage and antioxidant capacity, has been validated in several pathologies, but not in left ventricular hypertrophy (LVH). The aim of this study was to design and calculate a plasma oxidative stress global index for patients with LVH. Methods: A total of 70 consecutive adult patients were recruited in our institution and assigned to one of the two study groups (control group/LVH group) by an echocardiography study. We evaluated plasmatic biomarkers of oxidative damage (malondialdehyde and thiolated proteins) and antioxidant defense (total thiols, reduced glutathione, total antioxidant capacity, catalase, and superoxide dismutase activities) by spectrophotometry/fluorimetry in order to calculate a plasma oxidative stress global index (OXY-SCORE) in relation to LVH. Results: The OXY-SCORE exhibited a highly significant difference between the groups (p < 0.001). The area under the receiver operating characteristic curve was 0.74 (95% confidence interval (CI), 0.62–0.85; p < 0.001). At a cut-off value of −1, the 68.6% sensitivity and 68.6% specificity values suggest that OXY-SCORE could be used to screen for LVH. A multivariable logistic regression model showed a positive association (p = 0.001) between OXY-SCORE and LVH [odds ratio = 0.55 (95% CI, 0.39–0.79)], independent of gender, age, smoking, glucose, systolic and diastolic arterial pressure, dyslipidemia, estimated glomerular filtration rate, body mass index, and valvular/coronary disease. Conclusion: OXY-SCORE could help in the diagnosis of LVH and could be used to monitor treatment response.This work was supported by a grant from Spanish Health Ministry (number FIS 16/02069) and Fondos Fede

Empoderamiento del alumnado adulto y de las personas mayores para una ciudadanía activa

Esta obra reúne iniciativas y experiencias de sensibilización y formación del profesorado y del alumnado adulto y mayor hacia una educación en competencias que contribuya a desarrollar la práctica de una ciudadanía activa compartiendo el tiempo libre, los conocimientos y las experiencias en proyectos sociales que consoliden y mejoren el entramado social de la ciudad, de las personas que la habitan y de la atención a sus necesidades. Su origen fue el proyecto CiudAct cofinanciado por el Programa Erasmus+ de la Unión Europea y en su desarrollo ha intervenido un equipo interinstitucional liderado por el Aula de Mayores+55 de la Universidad de Málaga y participado por el Centro de Profesorado «José Rodríguez Galán» de Antequera, la Asociación Cívica para la Prevención (ACP), la Asociación de Igualdad de Género Universitario (AIGU), y el Ayuntamiento de Faraján (Málaga). Con ellos, y con otras tantas instituciones y sus respectivos consorcios locales en toda Europa, se participa en la red supranacional Ciudades en Crecimiento.Programa Erasmus+ de la Unión Europea (referencia de proyecto 2015-1-ES01-KA104-014944

Evasion of Classical Complement Pathway Activation on Plasmodium falciparum-Infected Erythrocytes Opsonized by PfEMP1-Specific IgG

Members of the PfEMP1 protein family are expressed on the surface of P. falciparum-infected erythrocytes (IEs), where they contribute to the pathogenesis of malaria and are important targets of acquired immunity. Although the PfEMP1-specific antibody response is dominated by the opsonizing and complement-fixing subclasses IgG1 and IgG3, activation of the classical complement pathway by antibody-opsonized IEs does not appear to be a major immune effector mechanism. To study the molecular background for this, we used ELISA and flow cytometry to assess activation of the classical component pathway by recombinant and native PfEMP1 antigen opsonized by polyclonal and monoclonal PfEMP1-specific human IgG. Polyclonal IgG specific for VAR2CSA-type PfEMP1 purified from a pool of human immune plasma efficiently activated the classical complement pathway when bound to recombinant PfEMP1 in ELISA. In contrast, no activation of complement could be detected by flow cytometry when the same IgG preparation was used to opsonize IEs expressing the corresponding native PfEMP1 antigen. After engineering of a VAR2CSA-specific monoclonal antibody to facilitate its on-target hexamerization, complement activation was detectable in an ELISA optimized for uniform orientation of the immobilized antigen. In contrast, the antibody remained unable to activate complement when bound to native VAR2CSA on IEs. Our data suggest that the display of PfEMP1 proteins on IEs is optimized to prevent activation of the classical complement pathway, and thus represents a hitherto unappreciated parasite strategy to evade acquired immunity to malaria