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Immunotherapy is revolutionizing the treatment of diseases in which dysregulated immune responses have an important role. However, most of the immunotherapy strategies currently being developed engage the adaptive immune system. In the past decade, both myeloid (monocytes, macrophages and dendritic cells) and lymphoid (natural killer cells and innate lymphoid cells) cell populations of the innate immune system have been shown to display long-term changes in their functional programme through metabolic and epigenetic programming. Such reprogramming causes these cells to be either hyperresponsive or hyporesponsive, resulting in a changed immune response to secondary stimuli. This de facto innate immune memory, which has been termed ‘trained immunity’, provides a powerful ‘targeting framework’ to regulate the delicate balance of immune homeostasis, priming, training and tolerance. In this Opinion article, we set out our vision of how to target innate immune cells and regulate trained immunity to achieve long-term therapeutic benefits in a range of immune-related diseases. These include conditions characterized by excessive trained immunity, such as inflammatory and autoimmune disorders, allergies and cardiovascular disease and conditions driven by defective trained immunity, such as cancer and certain infections.Cells in the innate immune system can display adaptive characteristics that lead to increased responsiveness to secondary stimulation by pathogens. This innate immune memory has been termed ‘trained immunity’. Here, Mulder and colleagues describe the mechanisms responsible for the induction of trained immunity and propose strategies to regulate it as a potential treatment of immune-related diseases.

Trained immunity is a functional state of the innate immune response and is characterized by long-term epigenetic reprogramming of innate immune cells. This concept originated in the field of infectious diseases — training of innate immune cells, such as monocytes, macrophages and/or natural killer cells, by infection or vaccination enhances immune responses against microbial pathogens after restimulation. Although initially reported in circulating monocytes and tissue macrophages (termed peripheral trained immunity), subsequent findings indicate that immune progenitor cells in the bone marrow can also be trained (that is, central trained immunity), which explains the long-term innate immunity-mediated protective effects of vaccination against heterologous infections. Although trained immunity is beneficial against infections, its inappropriate induction by endogenous stimuli can also lead to aberrant inflammation. For example, in systemic lupus erythematosus and systemic sclerosis, trained immunity might contribute to inflammatory activity, which promotes disease progression. In organ transplantation, trained immunity has been associated with acute rejection and suppression of trained immunity prolonged allograft survival. This novel concept provides a better understanding of the involvement of the innate immune response in different pathological conditions, and provides a new framework for the development of therapies and treatment strategies that target epigenetic and metabolic pathways of the innate immune system.Trained immunity refers to the development of immunological memory in innate immune cells. Here, the authors examine the basic features of trained immunity, as well as its role and potential therapeutic targeting in immunopathologies that involve the kidney.

Trained immunity, also known as innate immune memory, is a persistent hyper-responsive functional state of innate immune cells. Accumulating evidence implicates trained immunity as an underlying mechanism of chronic inflammation in atherosclerotic cardiovascular disease. In this context, trained immunity is induced by endogenous atherosclerosis-promoting factors, such as modified lipoproteins or hyperglycaemia, causing broad metabolic and epigenetic reprogramming of the myeloid cell compartment. In addition to traditional cardiovascular risk factors, lifestyle factors, including unhealthy diets, sedentary lifestyle, sleep deprivation and psychosocial stress, as well as inflammatory comorbidities, have been shown to activate trained immunity-like mechanisms in bone marrow haematopoietic stem cells. In this Review, we discuss the molecular and cellular mechanisms of trained immunity, its systemic regulation through haematopoietic progenitor cells in the bone marrow, and the activation of these mechanisms by cardiovascular disease risk factors. We also highlight other trained immunity features that are relevant for atherosclerotic cardiovascular disease, including the diverse cell types that show memory characteristics and transgenerational inheritance of trained immunity traits. Finally, we propose potential strategies for the therapeutic modulation of trained immunity to manage atherosclerotic cardiovascular disease.In this Review, Riksen and colleagues discuss the molecular and cellular mechanisms of trained immunity, the activation of these mechanisms by cardiovascular risk factors, and how trained immunity might contribute to atherosclerosis and atherosclerotic cardiovascular disease. The authors also propose potential strategies for the therapeutic modulation of trained immunity in atherosclerotic cardiovascular disease.

Emotional stress is associated with increased risk of cardiovascular disease. We imaged the amygdala, a brain region involved in stress, to determine whether its resting metabolic activity predicts risk of subsequent cardiovascular events. Individuals aged 30 years or older without known cardiovascular disease or active cancer disorders, who underwent 18F-fluorodexoyglucose PET/CT at Massachusetts General Hospital (Boston, MA, USA) between Jan 1, 2005, and Dec 31, 2008, were studied longitudinally. Amygdalar activity, bone-marrow activity, and arterial inflammation were assessed with validated methods. In a separate cross-sectional study we analysed the relation between perceived stress, amygdalar activity, arterial inflammation, and C-reactive protein. Image analyses and cardiovascular disease event adjudication were done by mutually blinded researchers. Relations between amygdalar activity and cardiovascular disease events were assessed with Cox models, log-rank tests, and mediation (path) analyses. 293 patients (median age 55 years [IQR 45·0–65·5]) were included in the longitudinal study, 22 of whom had a cardiovascular disease event during median follow-up of 3·7 years (IQR 2·7–4·8). Amygdalar activity was associated with increased bone-marrow activity (r=0·47; p<0·0001), arterial inflammation (r=0·49; p<0·0001), and risk of cardiovascular disease events (standardised hazard ratio 1·59, 95% CI 1·27–1·98; p<0·0001), a finding that remained significant after multivariate adjustments. The association between amygdalar activity and cardiovascular disease events seemed to be mediated by increased bone-marrow activity and arterial inflammation in series. In the separate cross-sectional study of patients who underwent psychometric analysis (n=13), amygdalar activity was significantly associated with arterial inflammation (r=0·70; p=0·0083). Perceived stress was associated with amygdalar activity (r=0·56; p=0·0485), arterial inflammation (r=0·59; p=0·0345), and C-reactive protein (r=0·83; p=0·0210). In this first study to link regional brain activity to subsequent cardiovascular disease, amygdalar activity independently and robustly predicted cardiovascular disease events. Amygdalar activity is involved partly via a path that includes increased bone-marrow activity and arterial inflammation. These findings provide novel insights into the mechanism through which emotional stressors can lead to cardiovascular disease in human beings. None.

Plant morphogenesis is strongly dependent on the directional growth and the subsequent oriented division of individual cells. It has been shown that the plant cortical microtubule array plays a key role in controlling both these processes. This ordered structure emerges as the collective result of stochastic interactions between large numbers of dynamic microtubules. To elucidate this complex self-organization process a number of analytical and computational approaches to study the dynamics of cortical microtubules have been proposed. To date, however, these models have been restricted to two dimensional planes or geometrically simple surfaces in three dimensions, which strongly limits their applicability as plant cells display a wide variety of shapes. This limitation is even more acute, as both local as well as global geometrical features of cells are expected to influence the overall organization of the array. Here we describe a framework for efficiently simulating microtubule dynamics on triangulated approximations of arbitrary three dimensional surfaces. This allows the study of microtubule array organization on realistic cell surfaces obtained by segmentation of microscopic images. We validate the framework against expected or known results for the spherical and cubical geometry. We then use it to systematically study the individual contributions of global geometry, cell-edge induced catastrophes and cell-face induced stability to array organization in a cuboidal geometry. Finally, we apply our framework to analyze the highly non-trivial geometry of leaf pavement cells of Arabidopsis thaliana, Nicotiana benthamiana and Hedera helix. We show that our simulations can predict multiple features of the microtubule array structure in these cells, revealing, among others, strong constraints on the orientation of division planes.

Key Points Nanomedicine — the use of nanotechnology for medical purposes — is a fast-growing field that has had numerous applications in cancer and is now increasingly being considered for atherosclerosis, the major cause of cardiovascular disease. Several methods of targeting atherosclerotic plaques using nanoparticles have been explored, which can be classified into nonspecific targeting, specific targeting of the vasculature as well as specific targeting of plaque components either with synthetic nanoparticles or via interaction through a natural conduit. Nanoparticle-facilitated therapeutics can potentially be applied to target the liver and change lipid levels systemically, or they can consist of direct injections of high-density lipoprotein nanoparticles to enhance the transport of cholesterol in plaques to the liver for excretion. Nanotherapy can also be used to intervene in specific atherosclerotic plaque processes by depleting monocyte recruitment or decreasing plaque inflammation and neovascularization. Silencing of plaque inflammation after a clinical event — such as a myocardial infarction or stroke — using nanotherapy is a promising therapeutic paradigm as it may improve the effectiveness of subsequent (statin) therapy. Medical imaging is increasingly being applied to assess atherosclerosis and to evaluate the effects of therapeutic interventions. It allows the direct and non-invasive visualization of plaque build-up and plaque characteristics in animal models as well as in patients. Nanoparticle-enhanced diagnostics allow the molecular imaging of atherosclerotic plaques by several clinically available imaging modalities, including magnetic resonance imaging, computed tomography, positron emission tomography and ultrasound imaging. Multimodal nanoparticles have exhibited valuable roles in the evaluation and corroboration of targeting mechanisms. Although traditionally exploited to improve anticancer drug delivery, the potential uses of nanomedicine in the management of cardiovascular disease are now recognized. Here, Mulder and colleagues review recent advances in applying nanotechnology to the diagnosis and treatment of atherosclerosis. The use of nanotechnology for medical purposes — nanomedicine — has grown exponentially over the past few decades. This is exemplified by the US Food and Drug Administration's approval of several nanotherapies for various conditions, as well as the funding of nanomedical programmes worldwide. Although originally the domain of anticancer therapy, recent advances have illustrated the considerable potential of nanomedicine in the diagnosis and treatment of atherosclerosis. This Review elaborates on nanoparticle-targeting concepts in atherosclerotic disease, provides an overview of the use of nanomedicine in atherosclerosis, and discusses potential future applications and clinical benefits.

Cells in an aqueous environment absorb diffusing nutrient molecules through nanoscale protein channels in their outer membranes. Assuming that there are constraints on the number of such channels a cell can produce, we ask the question: given a nondepleting source of nutrients, what is the optimal distribution of these channels over the cell surface? We coarse-grain this problem, phrasing it as a diffusion problem with position-dependent Robin boundary conditions on the surface. The aim is to maximize the steady-state total flux through the partially absorbing surface under an integral constraint on the local reactivities. We develop an algorithm to tackle this problem that uses the stored and processed results of a particle-based simulation with reflective boundary conditions to a posteriori estimate absorption flux at essentially negligible additional computational cost. We validate the algorithm against a few cases for which analytical or semi-analytical results are available. We apply it to two examples: a spherical cell in the presence of a point source and a spheroidal cell with an isotropic source at infinity. In the former case, there is a significant gain relative to the homogeneous case, while in the latter case the gain is only 1 % .

Background Individualised optimisation of mechanical ventilation (MV) remains cumbersome in modern intensive care medicine. Computerised, model-based support systems could help in tailoring MV settings to the complex interactions between MV and the individual patient's pathophysiology. Therefore, we critically appraised the current literature on computational physiological models (CPMs) for individualised MV in the ICU with a focus on quality, availability, and clinical readiness. Methods A systematic literature search was conducted on 13 February 2023 in MEDLINE ALL, Embase, Scopus and Web of Science to identify original research articles describing CPMs for individualised MV in the ICU. The modelled physiological phenomena, clinical applications, and level of readiness were extracted. The quality of model design reporting and validation was assessed based on American Society of Mechanical Engineers (ASME) standards. Results Out of 6,333 unique publications, 149 publications were included. CPMs emerged since the 1970s with increasing levels of readiness. A total of 131 articles (88%) modelled lung mechanics, mainly for lung-protective ventilation. Gas exchange ( n  = 38, 26%) and gas homeostasis ( n  = 36, 24%) models had mainly applications in controlling oxygenation and ventilation. Respiratory muscle function models for diaphragm-protective ventilation emerged recently ( n  = 3, 2%). Three randomised controlled trials were initiated, applying the Beacon and CURE Soft models for gas exchange and PEEP optimisation. Overall, model design and quality were reported unsatisfactory in 93% and 21% of the articles, respectively. Conclusion CPMs are advancing towards clinical application as an explainable tool to optimise individualised MV. To promote clinical application, dedicated standards for quality assessment and model reporting are essential. Trial registration number PROSPERO— CRD42022301715 . Registered 05 February, 2022.

The prevalence of adult patients with congenital heart disease (CHD) has been reported with a high degree of variability. Prevalence estimates have been calculated using birth rate, birth prevalence, and assumed survival and derived from large administrative databases. To report more robust prevalence estimate, we performed a systematic review for studies concerning CHD prevalence in adults. Moreover, to diminish bias of calculated estimates, we conducted an evidence-based calculation for the Netherlands. A systematic database search was performed to identify reports on the prevalence of adult CHD. Bicuspid aortic valve, mitral valve prolapse, Marfan syndrome, cardiomyopathy, congenital arrhythmia, and spontaneously closed defects were excluded. In addition, CHD prevalence was calculated using birth rate, birth prevalence, and survival estimates. Our search yielded 10 publications on the prevalence of CHD in adults. Four reported results from population wide cross-sectional data, whereas in 6, prevalence was calculated. Mean prevalence reported by empirical studies was 3,562 per million when unspecified lesions were included and 2,297 per million when these were excluded. Mean prevalence derived from calculation was 3,536. Our calculated estimate was 3,228 per million adults. Taking these estimates as well as the limitations inherent to their derivation into consideration, the prevalence of CHD in the adult population is approximately 3,000 per million adults. This systematic review presents a comprehensive overview of publications on the prevalence of CHD in adults. The best available evidence suggests that overall prevalence of CHD in the adult population is in the region of 3,000 per million.

The organization of cortical microtubule arrays in higher plant cells is essential for organizing cell and tissue morphogenesis, but it is not clear how specific architectures are acquired and reconfigured in response to environmental cues. Lindeboom et al. ( 10.1126/science.1245533 , published online 7 November; see the Perspective by Roll-Mecak ) used live-cell imaging and genetic studies to show that the microtubule-severing protein, katanin, plays a crucial role in reorienting cortical arrays from transverse to longitudinal in Arabidopsis seedlings in response to blue light perception. Katanin localized to microtubule intersections where, stimulated by blue light receptors, it preferentially catalyzed the severing of the newer microtubule. The microtubule “plus” end created by severing were observed to grow preferentially, effectively building a new population of microtubules orthogonal to the initial array. The net effect of this process steers the growing seedling toward light. A self-organizing system makes the microtubule array in plants rearrange in order for the shoot to turn toward blue light. Environmental and hormonal signals cause reorganization of microtubule arrays in higher plants, but the mechanisms driving these transitions have remained elusive. The organization of these arrays is required to direct morphogenesis. We discovered that microtubule severing by the protein katanin plays a crucial and unexpected role in the reorientation of cortical arrays, as triggered by blue light. Imaging and genetic experiments revealed that phototropin photoreceptors stimulate katanin-mediated severing specifically at microtubule intersections, leading to the generation of new microtubules at these locations. We show how this activity serves as the basis for a mechanism that amplifies microtubules orthogonal to the initial array, thereby driving array reorientation. Our observations show how severing is used constructively to build a new microtubule array.