Recruitment of Human C1 Esterase Inhibitor Controls Complement Activation on Blood Stage Plasmodium falciparum Merozoites.

The complement system is a front-line defense system that opsonizes and lyses invading pathogens. To survive, microbes exposed to serum must evade the complement response. To achieve this, many pathogens recruit soluble human complement regulators to their surfaces and hijack their regulatory function for protection from complement activation. C1 esterase inhibitor (C1-INH) is a soluble regulator of complement activation that negatively regulates the classical and lectin pathways of complement to protect human tissue from aberrant activation. In this article, we show that Plasmodium falciparum merozoites, the invasive form of blood stage malaria parasites, actively recruit C1-INH to their surfaces when exposed to human serum. We identified PfMSP3.1, a member of the merozoite surface protein 3 family of merozoite surface proteins, as the direct interaction partner. When bound to the merozoite surface, C1-INH retains its ability to complex with and inhibit C1s, MASP1, and MASP2, the activating proteases of the complement cascade. P. falciparum merozoites that lack PfMSP3.1 showed a marked reduction in C1-INH recruitment and increased C3b deposition on their surfaces. However, these ΔPfMSP3.1 merozoites exhibit enhanced invasion of RBCs in the presence of active complement. This study characterizes an immune-evasion strategy used by malaria parasites and highlights the complex relationship between merozoites and the complement system.

Protocol for a pragmatic randomised controlled feasibility study of MS WorkSmart: an online intervention for Australians with MS who are employed.

INTRODUCTION: Multiple sclerosis (MS) causes a wide variety of symptoms. Loss of income due to sickness and early retirement comprise one-third of the total cost of MS in Australia. An intervention that maximises work productivity and keeps people with MS in the workforce for longer could provide a large societal cost saving and improve quality of life. The aim is to test the feasibility of delivering and evaluating a 10-week digitally delivered intervention called 'MS WorkSmart'. Findings will provide insights into participant profiles and address key methodological and procedural uncertainties (recruitment, retention, intervention adherence and engagement, and selection of primary outcome) in preparation for a subsequent definitive trial. METHODS AND ANALYSIS: A parallel-arm randomised controlled feasibility study, comparing those randomised to receive the MS WorkSmart package plus usual care (n=20) to those receiving usual care only (n=20). Australians with MS, aged 18-60 years, who are employed, and self-report work instability will be recruited from the Australian MS Longitudinal Study. Online surveys, at baseline and 1-month postintervention, will include MS-related work productivity loss and risk of job loss, MS work behaviour self-efficacy, health-related quality of life, fatigue severity, MS symptom impact on work, intention to retire due to MS, MS-related work difficulties, and awareness and readiness for change at work. Qualitative feedback will be obtained via a semistructured survey following the intervention (for participants) and via interviews (coaches). Analyses will be primarily descriptive and focus on the feasibility and acceptability of the intervention and study procedures. Progression criteria will guide decisions around whether to progress to a full trial. ETHICS AND DISSEMINATION: The study has been approved by the University of Tasmania Human Research Ethics Committee (H0024544). Findings will be disseminated via publication in peer-reviewed journals, conference presentations and community presentations. TRIAL REGISTRATION NUMBER: ACTRN12622000826741.

PIM activity in tumours: A key node of therapy resistance.

The PIM kinases are proto-oncogenes which have been shown to facilitate cell survival and proliferation to drive malignancy and resistance post-therapy. They are able to suppress cell death signals, sustain PI3K/AKT/mTORC1 pathway activity and regulate the MYC oncogenic program. Recent work has revealed PIM kinase essentiality for advanced tumour maintenance and described tumour sensitivity to small molecule inhibitors targeting PIM kinase in multiple malignancies.

Patient-derived Models of Abiraterone- and Enzalutamide-resistant Prostate Cancer Reveal Sensitivity to Ribosome-directed Therapy.

BACKGROUND: The intractability of castration-resistant prostate cancer (CRPC) is exacerbated by tumour heterogeneity, including diverse alterations to the androgen receptor (AR) axis and AR-independent phenotypes. The availability of additional models encompassing this heterogeneity would facilitate the identification of more effective therapies for CRPC. OBJECTIVE: To discover therapeutic strategies by exploiting patient-derived models that exemplify the heterogeneity of CRPC. DESIGN, SETTING, AND PARTICIPANTS: Four new patient-derived xenografts (PDXs) were established from independent metastases of two patients and characterised using integrative genomics. A panel of rationally selected drugs was tested using an innovative ex vivo PDX culture system. INTERVENTION: The following drugs were evaluated: AR signalling inhibitors (enzalutamide and galeterone), a PARP inhibitor (talazoparib), a chemotherapeutic (cisplatin), a CDK4/6 inhibitor (ribociclib), bromodomain and extraterminal (BET) protein inhibitors (iBET151 and JQ1), and inhibitors of ribosome biogenesis/function (RNA polymerase I inhibitor CX-5461 and pan-PIM kinase inhibitor CX-6258). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Drug efficacy in ex vivo cultures of PDX tissues was evaluated using immunohistochemistry for Ki67 and cleaved caspase-3 levels. Candidate drugs were also tested for antitumour efficacy in vivo, with tumour volume being the primary endpoint. Two-tailed t tests were used to compare drug and control treatments. RESULTS AND LIMITATIONS: Integrative genomics revealed that the new PDXs exhibited heterogeneous mechanisms of resistance, including known and novel AR mutations, genomic structural rearrangements of the AR gene, and a neuroendocrine-like AR-null phenotype. Despite their heterogeneity, all models were sensitive to the combination of ribosome-targeting agents CX-5461 and CX-6258. CONCLUSIONS: This study demonstrates that ribosome-targeting drugs may be effective against diverse CRPC subtypes including AR-null disease, and highlights the potential of contemporary patient-derived models to prioritise treatment strategies for clinical translation. PATIENT SUMMARY: Diverse types of therapy-resistant prostate cancers are sensitive to a new combination of drugs that inhibit protein synthesis pathways in cancer cells.