Comparison between real-world practice and application of the FRAX algorithm in the treatment of osteoporosis.

BACKGROUND AND AIMS: The most recent guidelines suggest treating patients whose FRAX 10-year fracture risk scores are ≥ 20%. However, this method of evaluation does not take into account parameters that are nonetheless relevant to the therapeutic choice. Our aim was to compare the therapeutic choices for treatment based on a wider assessment (real-world practice) with those based on FRAX scores, taking 20% as the cut-off score. METHODS: We obtained the medical history, bone mineral density (BMD) values, and the presence of major fragility fractures in a sample of 856 postmenopausal women. The 10-year FRAX risk of major osteoporotic fracture was calculated, and patients were grouped into risk classes ("FRAX < 20%" = low, "FRAX ≥ 20%" = high); we then compared the treated and untreated patients in each class. After an average interval of 2.5 years, changes in lumbar and femoral BMD and appearances of new fragility fractures were recorded. RESULTS: 83% of high-risk patients and 57% of low-risk patients were treated. The therapeutic decision was based mainly on densitometric values and the presence of vertebral fractures. At the 2.5 year follow-up, lumbar spine and femur BMD had decreased in the untreated group; 9.9% of the treated patients developed new vertebral fragility fractures, compared with 5.3% of the untreated patients. DISCUSSION AND CONCLUSIONS: Our wider assessment designated as at high fracture risk a group of patients who had not been identified by the FRAX assessment. FRAX could underestimate the risk of fracture in older people, for which the therapeutic choice should consider a broader approach, also based on individual patient's needs.

Dietary inflammatory index is associated with lung function in healthy older adults.

OBJECTIVES: Aging is associated with low-grade chronic inflammation contributing to a decline in lung performance. The Dietary Inflammatory Index (DII) has been introduced to evaluate the inflammatory potential of different diets, which may further affect individuals' respiratory function. This study investigates the association between DII and lung performance in older adults. METHODS: This cross-sectional study included 155 adults aged ≥65 y recruited at public gyms in Padua, Italy. Participants were assessed on medical history, biochemical parameters, body composition (through dual energy x-ray absorptiometry), anthropometry, and lung function (by spirometry). Based on individuals' dietary habits, we computed their DII and categorized participants in the lower DII (comprising those in the lowest DII tertile) or the higher DII (comprising those in the highest DII tertiles) groups. The association of DII with forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC) was tested through multivariable linear regression analyses in the total sample and stratified by body mass index (<25 kg/m2 versus ≥25 kg/m2). RESULTS: The mean age of the sample was 71.2 y and 80% were women. Individuals in the higher DII group had FEV1 and FVC values reduced by 0.15 L (95% CI, -0.29 to -0.01 L) and 0.25 L (95% CI, -0.43 to -0.07 L), respectively, as compared with those in the lower DII group. Results seemed to be more marked among participants with excess weight conditions. CONCLUSIONS: Pro-inflammatory diets may affect lung function in fit older people, and this effect may be exacerbated in overweight or obese individuals.

Broadly Applicable Hydrogel Fabrication Procedures Guided by YAP/TAZ-Activity Reveal Stiffness, Adhesiveness, and Nuclear Projected Area as Checkpoints for Mechanosensing.

Mechanical signals are pivotal ingredients in how cells perceive and respond to their microenvironments, and to synthetic biomaterials that mimic them. In spite of increasing interest in mechanobiology, probing the effects of physical cues on cell behavior remains challenging for a cell biology laboratory without experience in fabrication of biocompatible materials. Hydrogels are ideal biomaterials recapitulating the physical cues that natural extracellular matrices (ECM) deliver to cells. Here, protocols are streamlined for the synthesis and functionalization of cell adhesive polyacrylamide-based (PAA-OH) and fully-defined polyethyleneglycol-based (PEG-RGD) hydrogels tuned at various rigidities for mechanobiology experiments, from 0.3 to >10 kPa.  The mechanosignaling properties of these hydrogels are investigated in distinct cell types by monitoring the activation state of YAP/TAZ. By independently modulating substrate stiffness and adhesiveness, it is found that although ECM stiffness represents an overarching mechanical signal, the density of adhesive sites does impact on cellular mechanosignaling at least at intermediate rigidity values, corresponding to normal and pathological states of living tissues. Using these tools, it is found that YAP/TAZ nuclear accumulation occurs when the projected area of the nucleus surpasses a critical threshold of approximatively 150 µm2 . This work suggests the existence of distinct checkpoints for cellular mechanosensing.

Simple yet effective methods to probe hydrogel stiffness for mechanobiology.

In spite of tremendous advances made in the comprehension of mechanotransduction, implementation of mechanobiology assays remains challenging for the broad community of cell biologists. Hydrogel substrates with tunable stiffness are essential tool in mechanobiology, allowing to investigate the effects of mechanical signals on cell behavior. A bottleneck that slows down the popularization of hydrogel formulations for mechanobiology is the assessment of their stiffness, typically requiring expensive and sophisticated methodologies in the domain of material science. Here we overcome such barriers offering the reader protocols to set-up and interpret two straightforward, low cost and high-throughput tools to measure hydrogel stiffness: static macroindentation and micropipette aspiration. We advanced on how to build up these tools and on the underlying theoretical modeling. Specifically, we validated our tools by comparing them with leading techniques used for measuring hydrogel stiffness (atomic force microscopy, uniaxial compression and rheometric analysis) with consistent results on PAA hydrogels or their modification. In so doing, we also took advantage of YAP/TAZ nuclear localization as biologically validated and sensitive readers of mechanosensing, all in all presenting a suite of biologically and theoretically proven protocols to be implemented in most biological laboratories to approach mechanobiology.

Single-cell analyses reveal YAP/TAZ as regulators of stemness and cell plasticity in Glioblastoma.

Glioblastoma (GBM) is a devastating human malignancy. GBM stem-like cells (GSCs) drive tumor initiation and progression. Yet, the molecular determinants defining GSCs in their native state in patients remain poorly understood. Here we used single cell datasets and identified GSCs at the apex of the differentiation hierarchy of GBM. By reconstructing the GSCs' regulatory network, we identified the YAP/TAZ coactivators as master regulators of this cell state, irrespectively of GBM subtypes. YAP/TAZ are required to install GSC properties in primary cells downstream of multiple oncogenic lesions, and required for tumor initiation and maintenance in vivo in different mouse and human GBM models. YAP/TAZ act as main roadblock of GSC differentiation and their inhibition irreversibly lock differentiated GBM cells into a non-tumorigenic state, preventing plasticity and regeneration of GSC-like cells. Thus, GSC identity is linked to a key molecular hub integrating genetics and microenvironmental inputs within the multifaceted biology of GBM.

Reprogramming normal cells into tumour precursors requires ECM stiffness and oncogene-mediated changes of cell mechanical properties.

Defining the interplay between the genetic events and microenvironmental contexts necessary to initiate tumorigenesis in normal cells is a central endeavour in cancer biology. We found that receptor tyrosine kinase (RTK)-Ras oncogenes reprogram normal, freshly explanted primary mouse and human cells into tumour precursors, in a process requiring increased force transmission between oncogene-expressing cells and their surrounding extracellular matrix. Microenvironments approximating the normal softness of healthy tissues, or blunting cellular mechanotransduction, prevent oncogene-mediated cell reprogramming and tumour emergence. However, RTK-Ras oncogenes empower a disproportional cellular response to the mechanical properties of the cell's environment, such that when cells experience even subtle supra-physiological extracellular-matrix rigidity they are converted into tumour-initiating cells. These regulations rely on YAP/TAZ mechanotransduction, and YAP/TAZ target genes account for a large fraction of the transcriptional responses downstream of oncogenic signalling. This work lays the groundwork for exploiting oncogenic mechanosignalling as a vulnerability at the onset of tumorigenesis, including tumour prevention strategies.

Publisher Correction: Reprogramming normal cells into tumour precursors requires ECM stiffness and oncogene-mediated changes of cell mechanical properties.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Biomaterials and engineered microenvironments to control YAP/TAZ-dependent cell behaviour.

Mechanical signals are increasingly recognized as overarching regulators of cell behaviour, controlling stemness, organoid biology, tissue development and regeneration. Moreover, aberrant mechanotransduction is a driver of disease, including cancer, fibrosis and cardiovascular defects. A central question remains how cells compute a host of biomechanical signals into meaningful biological behaviours. Biomaterials and microfabrication technologies are essential to address this issue. Here we review a large body of evidence that connects diverse biomaterial-based systems to the functions of YAP/TAZ, two highly related mechanosensitive transcriptional regulators. YAP/TAZ orchestrate the response to a suite of engineered microenviroments, emerging as a universal control system for cells in two and three dimensions, in static or dynamic fashions, over a range of elastic and viscoelastic stimuli, from solid to fluid states. This approach may guide the rational design of technological and material-based platforms with dramatically improved functionalities and inform the generation of new biomaterials for regenerative medicine applications.