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The article discusses the evolving field of cardiac safety in drug discovery and the need for integration with immunology. It highlights the historical evolution of cardiac safety assessments and the increasing attention given to hemodynamic and structural alterations. The article also discusses the emergence of novel models, such as in silico predictions and 3D tissue-based systems, and the importance of incorporating immune components in these models. It specifically focuses on the risk of immune-mediated myocarditis and the need for more complex human-based in vitro models. The article concludes by discussing the potential of advanced cellular models, such as organ-on-chip systems, in improving cardiac safety assessments and reducing animal testing. [Extracted from the article]

Summary The immunosuppressive transmembrane protein PD-L1 was shown to traffic via the multivesicular body (MVB) and to be released on exosomes. A high-content siRNA screen identified the endosomal sorting complexes required for transport (ESCRT)-associated protein ALIX as a regulator of both EGFR activity and PD-L1 surface presentation in basal-like breast cancer (BLBC) cells. ALIX depletion results in prolonged and enhanced stimulation-induced EGFR activity as well as defective PD-L1 trafficking through the MVB, reduced exosomal secretion, and its redistribution to the cell surface. Increased surface PD-L1 expression confers an EGFR-dependent immunosuppressive phenotype on ALIX-depleted cells. An inverse association between ALIX and PD-L1 expression was observed in human breast cancer tissues, while an immunocompetent mouse model of breast cancer revealed that ALIX-deficient tumors are larger and show an increased immunosuppressive environment. Our data suggest that ALIX modulates immunosuppression through regulation of PD-L1 and EGFR and may, therefore, present a diagnostic and therapeutic target for BLBC. [ABSTRACT FROM AUTHOR]

Background Exosomes are nanometer-sized vesicles released from cells into the blood, where they can transmit signals throughout the body. Shown to act on the heart, exosomes’ composition and the signaling pathways they activate have not been explored. We hypothesized that endogenous plasma exosomes can communicate signals to the heart and provide protection against ischemia and reperfusion injury. Objectives This study sought to isolate and characterize exosomes from rats and healthy volunteers, evaluate their cardioprotective actions, and identify the molecular mechanisms involved. Methods The exosome-rich fraction was isolated from the blood of adult rats and human volunteers and was analyzed by protein marker expression, transmission electron microscopy, and nanoparticle tracking analysis. This was then used in ex vivo, in vivo, and in vitro settings of ischemia-reperfusion, with the protective signaling pathways activated on cardiomyocytes identified using Western blot analyses and chemical inhibitors. Results Exosomes exhibited the expected size and expressed marker proteins CD63, CD81, and heat shock protein (HSP) 70. The exosome-rich fraction was powerfully cardioprotective in all tested models of cardiac ischemia-reperfusion injury. We identified a pro-survival signaling pathway activated in cardiomyocytes involving toll-like receptor (TLR) 4 and various kinases, leading to activation of the cardioprotective HSP27. Cardioprotection was prevented by a neutralizing antibody against a conserved HSP70 epitope expressed on the exosome surface and by blocking TLR4 in cardiomyocytes, identifying the HSP70/TLR4 communication axis as a critical component in exosome-mediated cardioprotection. Conclusions Exosomes deliver endogenous protective signals to the myocardium by a pathway involving TLR4 and classic cardioprotective HSPs. [ABSTRACT FROM AUTHOR]

Background: Recently years have seen the increasing evidence identifying that OXPHOS is involved in different processes of tumor progression and metastasis and has been proposed to be a potential therapeutical target for cancer treatment. However, the exploration in oxidative phosphorylation-mediated chemoresistance is still scarce. In our study, we identify exosomal transfer leads to chemoresistance by reprogramming metabolic phenotype in recipient cells. Methods: RNA sequencing analysis was used to screen altered targets mediating exosome transfer-induced chemoresistance. Seahorse assay allowed us to measure mitochondrial respiration. Stemness was measured by spheroids formation assay. Serum exosomes were isolated for circ_0001610 quantification. Results: The induced oxidative phosphorylation leads to more stem-like properties, which is dependent on the transfer of exosomal circ_0001610. Exosome transfer results in the removal of miR-30e-5p-mediated suppression of PGC-1a, a master of mitochondrial biogenesis and function. Consequently, increased PGC-1a reshapes cellular metabolism towards oxidative phosphorylation, leading to chemoresistance. Inhibition of OXPHOS or exosomal si-circ_0001610 increases the sensitivity of chemotherapy by decreasing cell stemness in vitro and in vivo . Conclusion: Our data suggests that exosomal circ_0001610-induced OXPHOS plays an important role in chemoresistance and supports a therapeutical potential of circ_0001610 inhibitors in the treatment of oxaliplatin-resistant colorectal cancer by manipulating cell stemness., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Background: Advanced head and neck squamous cell carcinoma (HNSCC) is associated with a poor prognosis, and biomarkers that predict response to treatment are highly desirable. The primary aim was to predict progression-free survival (PFS) with a multivariate risk prediction model., Methods: Experimental covariates were derived from blood samples of 56 HNSCC patients which were prospectively obtained within a Phase 2 clinical trial (NCT02633800) at baseline and after the first treatment cycle of combined platinum-based chemotherapy with cetuximab treatment. Clinical and experimental covariates were selected by Bayesian multivariate regression to form risk scores to predict PFS., Results: A 'baseline' and a 'combined' risk prediction model were generated, each of which featuring clinical and experimental covariates. The baseline risk signature has three covariates and was strongly driven by baseline percentage of CD33 + CD14 + HLADR high monocytes. The combined signature has six covariates, also featuring baseline CD33 + CD14 + HLADR high monocytes but is strongly driven by on-treatment relative change of CD8 + central memory T cells percentages. The combined model has a higher predictive power than the baseline model and was successfully validated to predict therapeutic response in an independent cohort of nine patients from an additional Phase 2 trial (NCT03494322) assessing the addition of avelumab to cetuximab treatment in HNSCC. We identified tissue counterparts for the immune cells driving the models, using imaging mass cytometry, that specifically colocalized at the tissue level and correlated with outcome., Conclusions: This immune-based combined multimodality signature, obtained through longitudinal peripheral blood monitoring and validated in an independent cohort, presents a novel means of predicting response early on during the treatment course., Funding: Daiichi Sankyo Inc, Cancer Research UK, EU IMI2 IMMUCAN, UK Medical Research Council, European Research Council (335326), Merck Serono. Cancer Research Institute, National Institute for Health Research, Guy's and St Thomas' NHS Foundation Trust and The Institute of Cancer Research., Clinical Trial Number: NCT02633800., Competing Interests: PB is a shareholder of Nano Clinical Ltd, RM, FF, GA, GW, LD, AM, FW, JV, MG, JO, JA, ST, MD No competing interests declared, KN has received honoraria from Pfizer, GSK/Tesaro and Boheringer Ingleheim, and has had travel/accommodation/expenses paid for by Tesaro, SK has received research funding in the form of a grant from Novartis and Celgene, JD, JG is in employment with Daichii Sankyo, and has stock and other ownership interests, research funding within Daichii Sankyo and has had travel/accommodation/expenses paid for by Daichii Sankyo, KH has received honoraria from Amgen; Arch Oncology; AstraZeneca; Boehringer-Ingelheim; Bristol-Myers Squibb; Codiak; Inzen; Merck; MSD; Pfizer; Replimune and is on a speakers' bureau for Amgen, AstraZeneca; Bristol-Myers Squibb; Merck, MSD; Pfizer. KH has also received research funding from AstraZeneca, Boehringer-Ingelheim, MSD and Replimune, MF has received institutional research funding from AstraZeneca, Boehringer-Ingelheim, Merck and MSD and serves in a consulting or advisory role to Achilles, Astrazeneca, Bayer, Bristol-Myers Squibb, Celgene, Guardant Health, Merck, MSD, Nanobiotix, Novartis, Oxford VacMedix, Pfizer, Roche, Takeda, UltraHuman, AC has stock and other ownership interests with Saddle Point Science Limited, TN has received research funding from Astrazeneca and Daichii Sankyo. TN is a founder and shareholder in Nano Clinical Ltd, and PRB is a shareholder, (© 2022, Barber, Mustapha, Flores-Borja et al.)

The past decade has witnessed an exponential increase in the number of publications referring to extracellular vesicles (EVs). For many years considered to be extracellular debris, EVs are now seen as novel mediators of endocrine signalling via cell-to-cell communication. With the capability of transferring proteins and nucleic acids from one cell to another, they have become an attractive focus of research for different pathological settings and are now regarded as both mediators and biomarkers of disease including cardio-metabolic disease. They also offer therapeutic potential as signalling agents capable of targeting tissues or cells with specific peptides or miRNAs. In this review, we focus on the role that microvesicles (MVs) and exosomes, the two most studied classes of EV, have in diabetes, cardiovascular disease, endothelial dysfunction, coagulopathies, and polycystic ovary syndrome. We also provide an overview of current developments in MV/exosome isolation techniques from plasma and other fluids, comparing different available commercial and non-commercial methods. We describe different techniques for their optical/biochemical characterization and quantitation. We also review the signalling pathways that exosomes and MVs activate in target cells and provide some insight into their use as biomarkers or potential therapeutic agents. In summary, we give an updated focus on the role that these exciting novel nanoparticles offer for the endocrine community., (© 2016 Society for Endocrinology.)