Heme oxygenase-1 and carbon monoxide suppress the pathogenesis of experimental cerebral malaria

Cerebral malaria claims more than 1 million lives per year. We report that heme oxygenase-1 (HO-1, encoded by Hmox1) prevents the development of experimental cerebral malaria (ECM). BALB/c mice infected with Plasmodium berghei ANKA upregulated HO-1 expression and activity and did not develop ECM. Deletion of Hmox1 and inhibition of HO activity increased ECM incidence to 83% and 78%, respectively. HO-1 upregulation was lower in infected C57BL/6 compared to BALB/c mice, and all infected C57BL/6 mice developed ECM (100% incidence). Pharmacological induction of HO-1 and exposure to the end-product of HO-1 activity, carbon monoxide (CO), reduced ECM incidence in C57BL/6 mice to 10% and 0%, respectively. Whereas neither HO-1 nor CO affected parasitemia, both prevented blood-brain barrier (BBB) disruption, brain microvasculature congestion and neuroinflammation, including CD8(+) T-cell brain sequestration. These effects were mediated by the binding of CO to hemoglobin, preventing hemoglobin oxidation and the generation of free heme, a molecule that triggers ECM pathogenesis.     

A crucial role for the C‐terminal domain of exported protein 1 during the mosquito and hepatic stages of the Plasmodium berghei life cycle

Intracellular Plasmodium parasites develop inside a parasitophorous vacuole (PV), a specialised compartment enclosed by a membrane (PVM) that contains proteins of both host and parasite origin. Although exported protein 1 (EXP1) is one of the earliest described parasitic PVM proteins, its function throughout the Plasmodium life cycle remains insufficiently understood. Here, we show that whereas the N‐terminus of Plasmodium berghei EXP1 (PbEXP1) is essential for parasite survival in the blood, parasites lacking PbEXP1's entire C‐terminal (CT) domain replicate normally in the blood but cause less severe pathology than their wild‐type counterparts. Moreover, truncation of PbEXP1's CT domain not only impairs parasite development in the mosquito but also abrogates PbEXP1 localization to the PVM of intrahepatic parasites, severely limiting their replication and preventing their egress into the blood. Our findings highlight the importance of EXP1 during the Plasmodium life cycle and identify this protein as a promising target for antiplasmodial intervention.     

Naphthoquinones from Euclea pseudebenus

Diospyrin, isodiospyrin, 8′-hydroxydiospyrin, racemic 8′-hydroxyisodiospyrin and two other naphthoquinones have been isolated from Euclea pseudebenus. Euelein is recognized to be identical to diospyrin.     

Mass separation and in vitro immunological activity of membrane-fractionated polysaccharides from fruiting body and mycelium of Agaricus subrufescens

Membrane technology has been applied to separate polysaccharides from Agaricus subrufescens (ASPs). The membrane-retained fractions and unfractionated preparations have been tested for in vitro immunological activity. Both the microfiltration (MF) and ultrafiltration (UF1) membranes were able to separate high-molecular weight polysaccharides from fruiting body (ASP-FB) and submerge-fermented mycelium (ASP-SmF) extracts. All fractions showed immunostimulatory effects on RAW 264.7 macrophages, measured by TNF-??, iNOs gene expression, and NO production. In contrast, antibody and proliferation levels in B lymphoblastoid SKW 6.4 cells were significantly increased after treatment with ASP-FB, but did not with ASP-SmF preparations. The ASPs- and LPS-induced stimulation could be differentiated by the finding that polymyxin B, a specific inhibitor of LPS, did not significantly affect the immunoactivating response and proliferation activity of ASPs on macrophages and B cells, respectively. Furthermore, the ASP-FB treatment was unable to induce IL-6 production by B cells unlike LPS activation, sustaining distinct signaling pathways for ASP-FB and LPS. The overall results provided additional information about the action of ASPs on the immune system and support the membrane method to separate and concentrate high-molecular weight ASPs for immunopharmacological and biotechnological applications.     

The Nuclear Envelope Protein,LAP1B,Is a Novel Protein Phosphatase 1 Substrate

Protein phosphatase 1 (PP1) binding proteins are quintessential regulators, determining substrate specificity and defining subcellular localization and activity of the latter. Here, we describe a novel PP1 binding protein, the nuclear membrane protein lamina associated polypeptide 1B (LAP1B), which interacts with the DYT1 dystonia protein torsinA. The PP1 binding domain in LAP1B was here identified as the REVRF motif at amino acids 55-59. The LAP1B:PP1 complex can be immunoprecipitated from cells in culture and rat cortex and the complex was further validated by yeast co-transformations and blot overlay assays. PP1, which is enriched in the nucleus, binds to the N-terminal nuclear domain of LAP1B, as shown by immunocolocalization and domain specific binding studies. PP1 dephosphorylates LAP1B, confirming the physiological relevance of this interaction. These findings place PP1 at a key position to participate in the pathogenesis of DYT1 dystonia and related nuclear envelope-based diseases.