Asia-Pacific International Center of Excellence in Malaria Research: Maximizing Impact on Malaria Control Policy and Public Health in Cambodia and Papua New Guinea

The Asia-Pacific International Center of Excellence in Malaria Research (ICEMR) was funded in 2016 to conduct a coordinated set of field and in-depth biological studies in Cambodia and Papua New Guinea (PNG), in sites that span the range of transmission intensities currently found in the Asia-Pacific regions. The overall objective is to gain an understanding of key parasite, human host, and vector factors involved in maintaining transmission in the face of intensified control and elimination programs, and to develop novel approaches to identify and target residual transmission foci. In this article, we will describe how the ICEMR program was designed to address key knowledge gaps and priority areas for the malaria control programs in each country. In PNG, partners have worked together on two consecutive ICEMR grants (2009-2016 and 2017-2024) and we present a case study of the partnership and engagement approach that has led to stronger coordination of research activities and integration with program, informing country-level strategic planning and prioritization of control activities. In both settings, the ICEMR program has generated insights into transmission foci, risk factors for ongoing transmission, highlighting the hidden burden of vivax malaria, and the need for additional complementary vector control tools. Finally, we will summarize the emerging research questions and priority areas-namely surveillance, vivax malaria, new vector control tools, and community/health systems-oriented approaches-where further tool development and implementation research have been identified as being needed to guide policy.

POS0468 EXTRACELLULAR VESICLES FROM SERUM OF MYOSITIS PATIENTS AS CIRCULATING BIOMARKERS AND DISEASE MEDIATORS

Background

Inflammatory myopathies (IM) are a heterogeneous group of disorders characterized by autoimmune inflammatory destruction of skeletal muscles. It is many times associated with lung, skin and joint involvement. Identifying biomarkers that can differentiate IM from other muscle disorders may elucidate the pathophysiology of IM, guide novel therapies, monitor disease activity/response to treatments and predict prognosis. Exosomes are membrane-bound nanovesicles with diameters of 30-150 nm that contain multiple proteins, nucleic acid, lipids and other molecules in a tissue- and cell-specific manner. Exosomes are secreted by a large variety of cells, play major roles in cell-cell interactions, and have recently emerged as circulating biomarkers in a variety of pathological conditions, including several autoimmune diseases.

Objectives

To characterize exosomes from serum of IM patients, analyze protein expression and study their potential mediators of disease pathologies.

Methods

Serum was collected from patients suffering from IM(n=5) and from patients suffering from Becker (BMD) and Duchenne (DMD) muscular dystrophies (n=6). Exosomes were isolated by Exoquick precipitation and analyzed for size distribution and by nanoparticle tracking analysis (NTA) and by Western blot for exosome markers. The effects of the isolated EVs on human satellite cell proliferation and differentiation and macrophage activation were examined.

Results

Exosomes from IM patients decreased human satellite cell proliferation (51%, P<0.01) and inhibited their myogenic differentiation as indicated by lower fusion index (24% inhibition, P<0.01) and expression of myosin heavy chain (72% inhibition, P<0.001). Similar results were obtained also with exosomes derived from DMD and BMD patients; however, their inhibitory effect were more pronounced on MyoG expression. Treatment of macrophages with exosomes from IM patients significantly increased the expression of IL-10 (3-fold, P<0.001), compared to exosomes of healthy controls and DMD patients. Another significant difference was in the expression of signaling molecules: Thus, exosomes from BMD patients increased the phosphorylation of Erk and p38, whereas a smaller effect was induced by IM exosomes.

Conclusion

Exosomes from IM patients decrease satellite cell proliferation and myogenic differentiation compared to healthy exosomes. In addition, these exosomes increased the expression of IL-10 in macrophages. These effects are unique to exosomes of IM patients compared to muscular dystrophies. These promising results suggest that serum exosomes should be further investigated as a novel biomarker with potential therapeutic implications.

Disclosure of Interests

Shaye Kivity Speakers bureau: BI, Abbvie, Lilly, Pfizer, Janssen, Neopharm, Grant/research support from: Sobi, Haya Kravitz: None declared, Coral Cohen: None declared, Darya Margoulis: None declared, Moshe Amar: None declared, Gila Kazimirsky: None declared, David Ozeri Speakers bureau: Neopharm, Consultant of: Abbvie, Amir Dori Grant/research support from: Biogen, Chaya Brodie Grant/research support from: Biogen.

STRIVE PNG: using a partnership-based approach in implementation research to strengthen surveillance and health systems in Papua New Guinea

Successful implementation research requires effective and equitable relationships between policy-makers, researchers and implementers to effect evidence-based systems change. However, mainstream research grant models between Global North and Global South institutions often (unintentionally) reinforce power imbalances between partners, which result in missed opportunities for knowledge and learning exchange between policy-makers, researchers and implementers.

This case study, centred on the STRIVE PNG project, describes how a partnership-based approach has been used to establish, maintain and review effective and equitable relationships between 13 partner organizations (independent research institutes, government health agencies and public health laboratories) to strengthen surveillance and health systems in Papua New Guinea (PNG). We provide an overview of key terms (with supporting conceptual frameworks), describe selected partnership processes and tools used within the project, and share observations regarding early outcomes achieved through this approach.

SC35 promotes sustainable stress-induced alternative splicing of neuronal acetylcholinesterase mRNA

Long-lasting alternative splicing of neuronal acetylcholinesterase (AChE) pre-mRNA occurs during neuronal development and following stress, altering synaptic properties. To explore the corresponding molecular events, we sought to identify mRNAs encoding for abundant splicing factors in the prefrontal cortex (PFC) following stress. Here we show elevated levels of the splicing factor SC35 in stressed as compared with naïve mice. In cotransfections of COS-1 and HEK293 cells with an AChE minigene allowing 3' splice variations, SC35 facilitated a shift from the primary AChE-S to the stress-induced AChE-R variant, while ASF/SF2 caused the opposite effect. Transfection with chimeric constructs comprising of SC35 and ASF/SF2 RRM/RS domains identified the SC35 RRM as responsible for AChE mRNA's alternative splicing. In poststress PFC neurons, increased SC35 mRNA and protein levels coincided with selective increase in AChE-R mRNA. In the developing mouse embryo, cortical progenitor cells in the ventricular zone displayed transient SC35 elevation concomitant with dominance of AChE-R over AChE-S mRNA. Finally, transgenic mice overexpressing human AChE-R, but not those overexpressing AChE-S, showed significant elevation in neuronal SC35 levels, suggesting a reciprocal reinforcement process. Together, these findings point to an interactive relationship of SC35 with cholinergic signals in the long-lasting consequences of stress on nervous system plasticity and development.

Striatal matrix neurons of the rat differentiate in culture from dissociated fetal progenitor cells isolated by buoyant density centrifugation

The adult striatum is composed of interlacing compartments known as patches (striosomes) and matrix, which differ with respect to a host of architectonic, biochemical and developmental parameters. We have exploited the 2-phase development of the striatum, employing buoyant-density fractionation to separate proliferating/undifferentiated neural precursors from the differentiated neurons of the E19 striatum. Primary cell cultures were established for the collected fractions, and immunohistochemistry for maturational and compartment-specific markers performed. The results indicate that the least buoyant, striatal precursors concentrate principally in the low buoyancy fraction of the gradient, and in culture express known matrix phenotype markers in an appropriate time frame.

Separation of dorsal and ventral dopaminergic neurons from embryonic rat mesencephalon by buoyant density fractionation: disassembling pattern in the ventral midbrain

The dopaminergic neurons of the ventral mesencephalon, though physically mixed with non-dopamine neurons, are organized into dorsal and ventral 'tiers' with regard to their ontogeny, efferent projections and their relative position in the various mesencephalic sub-nuclei. We have employed buoyant density fractionation to separate the dopaminergic neurons of the two compartments and compare their subsequent phenotype development with respect to their expression of the gene encoding tyrosine hydroxylase, the rate-limiting enzyme in the catecholamine biosynthetic pathway. Using immunocytochemistry, separately and combined with in situ hybridization, we demonstrate here that sedimentation of cell suspensions from E19 rat ventral mesencephalon on 5-step Percoll gradients produces cell fractions enriched in ventral and dorsal tier DA neurons, respectively.