LC3B labeling of the parasitophorous vacuole membrane of Plasmodium berghei liver stage parasites depends on the V-ATPase and ATG16L1

The protozoan parasite Plasmodium, the causative agent of malaria, undergoes an obligatory stage of intra-hepatic development before initiating a blood-stage infection. Productive invasion of hepatocytes involves the formation of a parasitophorous vacuole (PV) generated by the invagination of the host cell plasma membrane. Surrounded by the PV membrane (PVM), the parasite undergoes extensive replication. During intracellular development in the hepatocyte, the parasites provoke the Plasmodium-associated autophagy-related (PAAR) response. This is characterized by a long-lasting association of the autophagy marker protein, and ATG8 family member, LC3B with the PVM. LC3B localization at the PVM does not follow the canonical autophagy pathway since upstream events specific to canonical autophagy are dispensable. Here, we describe that LC3B localization at the PVM of Plasmodium parasites requires the V-ATPase and its interaction with ATG16L1. The WD40 domain of ATG16L1 is crucial for its recruitment to the PVM. Thus, we provide new mechanistic insight into the previously described PAAR response targeting Plasmodium liver stage parasites.

Feasibility of an Application-Based Outpatient Rehabilitation Program for Stroke Survivors: Acceptability and Preliminary Results for Patient-Reported Outcomes

BACKGROUND

The majority of stroke survivors experience long-term impairments. Regular physical activity and other lifestyle modifications play an important role in rehabilitation. Outpatient rehabilitation using telemedicine might be suitable to improve functional ability and long-term secondary prevention. The Strokecoach Intervention Program (SIP, Strokecoach GmbH, Cologne, Germany) comprises training, coaching and monitoring with the aim of improving or at least maintaining functional independence and preventing further stroke through more targeted physical activity. The SIP is provided as blended care, which refers to the integrated and coordinated delivery of healthcare services that combines traditional in-person interactions with technology-mediated interventions, optimizing the use of both face-to-face and virtual modalities to enhance patient outcomes.

OBJECTIVE

The aim of this study was to evaluate the acceptance of the SIP by the participants and its practical application, as well as to obtain initial indications of effects of the SIP on the basis of patient-related outcome measures, blood pressure measurements and recording of physical activity in parallel with the intervention.

METHODS

Data from individuals with stroke participating in the SIP were analyzed retrospectively. Within the SIP, participants received an application-based training program, were instructed to measure their blood pressure daily and to wear an activity tracker (pedometer). During the intervention period of either 6 or 12 weeks, the participants were supported and motivated by a personal coach via a messenger application. The primary outcomes of the analysis were recruitment, acceptance of and satisfaction with the SIP. Secondary outcomes included functional measures, mobility and health-related quality of life.

RESULTS

A total of 122 individuals with stroke could be recruited for the SIP. A total of 96 out of 122 were able to start the program (54% female, mean age 54.8 (SD = 13.1), 6.1 (SD = 6.6) years after stroke onset) and 88 completed the SIP. Participants wore the activity tracker on 66% and tracked their blood pressure on 72% of their intervention days. A further analyzed subgroup of 38 participants showed small improvements in patient-reported outcomes such as health-related quality of life (SF-36) with an increase of 12 points in the subdomain mental health, vitality (12.6) and physical functioning (9.1). However, no statistically significant improvements were found in other performance-based measures (Timed Up and Go test, gait speed).

CONCLUSIONS

This study showed that a blended therapy approach for stroke survivors with mild to moderate impairments in the chronic phase is feasible and was highly accepted by participants, who benefitted from the additional coaching.

Autophagy in protists and their hosts: When, how and why?

Pathogenic protists are a group of organisms responsible for causing a variety of human diseases including malaria, sleeping sickness, Chagas disease, leishmaniasis, and toxoplasmosis, among others. These diseases, which affect more than one billion people globally, mainly the poorest populations, are characterized by severe chronic stages and the lack of effective antiparasitic treatment. Parasitic protists display complex life-cycles and go through different cellular transformations in order to adapt to the different hosts they live in. Autophagy, a highly conserved cellular degradation process, has emerged as a key mechanism required for these differentiation processes, as well as other functions that are crucial to parasite fitness. In contrast to yeasts and mammals, protist autophagy is characterized by a modest number of conserved autophagy-related proteins (ATGs) that, even though, can drive the autophagosome formation and degradation. In addition, during their intracellular cycle, the interaction of these pathogens with the host autophagy system plays a crucial role resulting in a beneficial or harmful effect that is important for the outcome of the infection. In this review, we summarize the current state of knowledge on autophagy and other related mechanisms in pathogenic protists and their hosts. We sought to emphasize when, how, and why this process takes place, and the effects it may have on the parasitic cycle. A better understanding of the significance of autophagy for the protist life-cycle will potentially be helpful to design novel anti-parasitic strategies.

Same, same but different: Exploring Plasmodium cell division during liver stage development

Plasmodium parasites have a complex life cycle alternating between a mosquito and a vertebrate host. Following the bite of an Anopheles female mosquito, Plasmodium sporozoites are transmitted from the skin to the liver; their first place of replication within the host. Successfully invaded sporozoites undergo a massive replication and growth involving asynchronous DNA replication and division that results in the generation of tens of thousands or even hundreds of thousands of merozoites depending on the Plasmodium species. The generation of a high number of daughter parasites requires biogenesis and segregation of organelles to finally reach a relatively synchronous cytokinesis event. At the end of liver stage (LS) development, merozoites are packed into merosomes and released into the bloodstream. They are then liberated and infect red blood cells to again produce merozoites by schizogony for the erythrocytic stage of the life cycle. Although parasite LS and asexual blood stage (ABS) differ in many respects, important similarities exist between the two. This review focuses on the cell division of Plasmodium parasite LS in comparison with other life cycle stages especially the parasite blood stage.

Plasmodium berghei sporozoites in nonreplicative vacuole are eliminated by a PI3P-mediated autophagy-independent pathway

The protozoan parasite Plasmodium, causative agent of malaria, invades hepatocytes by invaginating the host cell plasma membrane and forming a parasitophorous vacuole membrane (PVM). Surrounded by this PVM, the parasite undergoes extensive replication. Parasites inside a PVM provoke the Plasmodium‐associated autophagy‐related (PAAR) response. This is characterised by a long‐lasting association of the autophagy marker protein LC3 with the PVM, which is not preceded by phosphatidylinositol 3‐phosphate (PI3P)‐labelling. Prior to productive invasion, sporozoites transmigrate several cells and here we describe that a proportion of traversing sporozoites become trapped in a transient traversal vacuole, provoking a host cell response that clearly differs from the PAAR response. These trapped sporozoites provoke PI3P‐labelling of the surrounding vacuolar membrane immediately after cell entry, followed by transient LC3‐labelling and elimination of the parasite by lysosomal acidification. Our data suggest that this PI3P response is not only restricted to sporozoites trapped during transmigration but also affects invaded parasites residing in a compromised vacuole. Thus, host cells can employ a pathway distinct from the previously described PAAR response to efficiently recognise and eliminate Plasmodium parasites.