Nanoanalytical analysis of bisphosphonate-driven alterations of microcalcifications using a 3D hydrogel system and in vivo mouse model

Vascular calcification predicts atherosclerotic plaque rupture and cardiovascular events. Retrospective studies of women taking bisphosphonates (BiPs), a proposed therapy for vascular calcification, showed that BiPs paradoxically increased morbidity in patients with prior acute cardiovascular events but decreased mortality in event-free patients. Calcifying extracellular vesicles (EVs), released by cells within atherosclerotic plaques, aggregate and nucleate calcification. We hypothesized that BiPs block EV aggregation and modify existing mineral growth, potentially altering microcalcification morphology and the risk of plaque rupture. Three-dimensional (3D) collagen hydrogels incubated with calcifying EVs were used to mimic fibrous cap calcification in vitro, while an ApoE^−/− mouse was used as a model of atherosclerosis in vivo. EV aggregation and formation of stress-inducing microcalcifications was imaged via scanning electron microscopy (SEM) and atomic force microscopy (AFM). In both models, BiP (ibandronate) treatment resulted in time-dependent changes in microcalcification size and mineral morphology, dependent on whether BiP treatment was initiated before or after the expected onset of microcalcification formation. Following BiP treatment at any time, microcalcifications formed in vitro were predicted to have an associated threefold decrease in fibrous cap tensile stress compared to untreated controls, estimated using finite element analysis (FEA). These findings support our hypothesis that BiPs alter EV-driven calcification. The study also confirmed that our 3D hydrogel is a viable platform to study EV-mediated mineral nucleation and evaluate potential therapies for cardiovascular calcification.

Atherosclerotic plaque rupture is the leading cause of myocardial infarction and stroke (1, 2). Studies assessing the correlation between calcium scores and cardiovascular events have demonstrated a predictive power that is superior to and independent from that of lipid scores (3, 4). Additionally, clinical imaging studies have revealed that the risk of plaque rupture is further heightened by the presence of small, “spotty” calcifications, or microcalcifications (5, 6), and cardiovascular risk is inversely correlated with the size of calcific deposits, quantified as a calcium density score (7). Indeed, computational modeling has demonstrated that, while large calcifications can reinforce the fibrous cap (8), microcalcifications (typically 5 to 15 μm in diameter) uniquely mediate an increase in mechanical stress of the relatively soft, collagen-rich fibrous cap (9–12).Histologic studies have revealed the presence of cell-derived vesicles within calcifying atherosclerotic lesions (13–16). The inflammatory environment of the atherosclerotic lesion can induce vascular smooth muscle cells (vSMCs) to take on an osteochondrogenic phenotype and release calcifying extracellular vesicles (EVs) (17–19). Macrophages have also been shown to release procalcifying vesicles (20, 21). Thus, just as bone formation is hypothesized to be an active, cell-driven process (22, 23), mediated by calcifying matrix vesicles, atheroma-associated calcification may similarly be initiated by the production and aggregation of calcifying EVs (11, 20, 24–28).One proposed strategy for halting pathologic calcification has been the use of bisphosphonates (BiPs). BiPs are analogs of pyrophosphate (29), a naturally occurring compound derived in vivo from adenosine triphosphate (ATP) (30). Pyrophosphate binds to calcium phosphate and inhibits calcification via physicochemical mechanisms, namely, by blocking calcium and phosphate ions from forming crystals, preventing crystal aggregation, and preventing mineral transformation from amorphous calcium phosphate to hydroxyapatite (29). BiPs were identified as pyrophosphate analogs that, unlike pyrophosphate itself, resist enzymatic hydrolysis. A second, distinct property of BiPs is the ability to inhibit bone resorption via biological activity directed against osteoclasts following osteoclast endocytosis of the BiP molecule adsorbed to the surface of bone (29, 31). First-generation, or nonnitrogen-containing BiPs, are incorporated into nonhydrolyzable ATP analogs, and induce osteoclast apoptosis by limiting ATP-dependent enzymes. In contrast, nitrogen-containing BiPs inhibit farnesyl pyrophosphate synthetase and thereby induce osteoclast apoptosis (31).In vivo animal investigations have been performed to explore the potential for BiPs to inhibit cardiovascular calcification. Studies of first-generation BiPs revealed that the doses required to inhibit cardiovascular calcification also critically compromised normal bone mineralization (29, 32). However, newer, nitrogen-containing BiPs effectively arrested cardiovascular calcification in animal models at doses that did not compromise bone formation (32). Further, while it has been proposed that BiP treatment modifies cardiovascular calcification via its impact on bone-regulated circulating calcium and phosphate levels, a study in uremic rats demonstrated that BiP treatment inhibited medial aortic calcification with no significant change in plasma calcium and phosphate levels (33). The same study demonstrated that BiP treatment inhibited calcification of explanted rat aortas, indicating that BiPs can act directly on vascular tissue, independent of bone metabolism (33).Retrospective clinical data examining the effect of BiP therapy on cardiovascular calcification has demonstrated conflicting findings and intriguing paradoxes. In women with chronic kidney disease, BiP therapy decreased the mortality rate for patients without a prior history of cardiovascular disease (34), but for those patients with a history of prior cardiovascular events, BiP therapy was associated with an increased mortality rate (35). In another study, BiP therapy correlated with a lower rate of cardiovascular calcification in older patients (>65 y), but a greater rate in younger patients (<65 y) (36). These clinical findings motivated our study, in which we sought to further understand how BiP therapy impacts cardiovascular outcomes. Given that cardiovascular calcification, and especially the presence of microcalcification, is a strong and independent risk factor for adverse cardiac events, and BiPs are prescribed to modulate pathologies of mineralization, we hypothesize that BiPs modulate cardiovascular outcomes by altering the dynamics of cardiovascular calcification.EVs are smaller than the resolution limits of traditional microscopy techniques, hindering studies into the mechanisms of calcification nucleation and growth. We previously developed an in vitro collagen hydrogel platform that allowed the visualization of calcific mineral development mediated by EVs isolated from vSMCs (24). Using superresolution microscopy, confocal, and electron microscopy techniques, we showed that calcification requires the accumulation of EVs that aggregate and merge to build mineral. Collagen serves as a scaffold that promotes associations between EVs that spread into interfibrillar spaces. The resultant mineral that forms within the collagen hydrogel appears spectroscopically similar to microcalcifications in human tissues and allows the study of these structures on the time scale of 1 wk. In this study, we utilized this three-dimensional (3D) acellular platform to examine the direct effect of ibandronate, a nitrogen-containing BiP, on the EV-directed nucleation and growth of microcalcifications, a process that cannot be isolated from cellular and tissue-level mechanisms in a more complex, in vivo system. In parallel, we utilized a mouse model of atherosclerosis to assess the effect of ibandronate therapy on plaque-associated calcification, comparing mineral morphologies between the in vitro and in vivo samples. We hypothesize that BiPs block EV aggregation and modify existing mineral growth, potentially altering microcalcification morphology and the risk of plaque rupture. Understanding the EV-specific action of BiPs is imperative both to develop anticalcific therapeutics targeting EV mineralization and to understand one potential mechanism driving the cardiovascular impact of BiPs used in clinical settings.     

Rapid dark aging of biomass burning as an overlooked source of oxidized organic aerosol

Oxidized organic aerosol (OOA) is a major component of ambient particulate matter, substantially impacting climate, human health, and ecosystems. OOA is readily produced in the presence of sunlight, and requires days of photooxidation to reach the levels observed in the atmosphere. High concentrations of OOA are thus expected in the summer; however, our current mechanistic understanding fails to explain elevated OOA during wintertime periods of low photochemical activity that coincide with periods of intense biomass burning. As a result, atmospheric models underpredict OOA concentrations by a factor of 3 to 5. Here we show that fresh emissions from biomass burning exposed to NO₂ and O₃ (precursors to the NO₃ radical) rapidly form OOA in the laboratory over a few hours and without any sunlight. The extent of oxidation is sensitive to relative humidity. The resulting OOA chemical composition is consistent with the observed OOA in field studies in major urban areas. Additionally, this dark chemical processing leads to significant enhancements in secondary nitrate aerosol, of which 50 to 60% is estimated to be organic. Simulations that include this understanding of dark chemical processing show that over 70% of organic aerosol from biomass burning is substantially influenced by dark oxidation. This rapid and extensive dark oxidation elevates the importance of nocturnal chemistry and biomass burning as a global source of OOA.

Highly oxidized organic aerosol (OOA) is a dominant component of particulate matter air pollution globally (1–3); however, sources of OOA remain uncertain, limiting the ability of models to accurately represent OOA and thus predict the associated climate, ecosystem, and health implications (4, 5). The current conceptual model of OOA formation suggests that anthropogenic OOA predominantly originates from the oxidation of volatile (VOCs), intermediate volatility (IVOCs), and semivolatile (SVOCs) organic compounds by the OH radical, resulting in lower-volatility products that condense to the particle phase (6). As the OH radical is formed through photolysis and has a very short atmospheric lifetime [less than a second (7)], this oxidation mechanism only occurs in the presence of sunlight. Further, the time scale for OOA formation through oxidation with OH in models is on the order of a few days (8). While this understanding is sufficient in explaining OOA concentrations in summer or periods with high solar radiation, atmospheric models fail to reproduce the observed concentration of OOA in the ambient atmosphere during winter and low-light conditions (9, 10). Fountoukis et al. (9) found simulated OOA concentrations significantly underestimated in wintertime Paris. Tsimpidi et al. (10) also reported an underprediction of simulated OOA globally in winter, suggesting missing sources of both primary OA (POA) and secondary formation pathways. This underproduction suggests a possible overlooked conversion pathway of organic vapors or particles to OOA that is not accounted for in current chemical transport and climate models.As stricter controls on fossil fuel combustion are implemented, residential biomass burning (BB) as a source of heating or cooking is becoming an increasingly important source of OA in urban environments (1, 11, 12). Further, increasing rates of wildfires from climate change are increasing the frequency of smoke-impacted days in urban areas (12–14). BB emissions include high concentrations of POA, SVOCs, IVOCs, and VOCs (15, 16), thus making BB a key source of OOA. Previous research has focused on quantifying the concentration of OOA formed through photochemical oxidation reactions (i.e., OH) with BB emissions (17, 18). However, oxidation of BB emissions in low or no sunlight is less well understood and is not included in chemical transport models. As opposed to OH, the NO₃ radical is formed through reactions with NO₂ and O₃ and is rapidly lost in the presence of sunlight (19). Thus, the NO₃ radical is only available in significant concentrations at night or other low-light conditions (20, 21). Previous research has established that biogenic VOCs may undergo oxidation at night when mixed with anthropogenic emissions containing NO₂ and O₃ (19, 22–27). There have been only a few studies that consider that nighttime oxidation of residential wood combustion may proceed through similar pathways (28–31); however, the magnitude and relevance to observed OOA in the ambient atmosphere has not yet been established. By combining laboratory experiments and ambient observations to inform a chemical transport model, we present strong evidence that nighttime oxidation of BB plumes (proceeding through reactions with O₃ and the NO₃ radical) is an important source of OOA.     

TSH/cAMP up-regulate sarco/endoplasmic reticulum Ca2+-ATPases expression and activity in PC Cl3 thyroid cells

OBJECTIVE: We recently reported that the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) 2b is the SERCA form preferentially expressed in rat thyroid. Moreover, SERCA2b expression dramatically decreases in virally transformed, highly tumorigenic, PC Cl3 thyroid cells. These results suggest that, in the thyroid, SERCA2b, in addition to its housekeeping role, is linked to differentiation and is a regulated gene. We therefore sought to study the effect of TSH, the main regulator of thyroid function, on SERCA2b expression and activity. METHODS: PC Cl3 cells were hormone starved in low-serum medium and stimulated for long (48 h) or short (1, 2 and 4 h) times. SERCA2b expression and activity were evaluated by Northern and Western blots, Ca2+-ATPase activity and Ca2+ store content. RESULTS: In PC Cl3 cells, SERCA2b mRNA and protein were induced twofold by a 48-h long treatment with TSH. Long-term elevation (48 h) of intracellular cAMP levels, by forskolin or 8-Br-cAMP, had similar effects on SERCA2b mRNA and protein. We also measured Ca2+-ATPase activity and Ca2+ store content. Both long (48 h) and short (0.5-1 h) treatments with TSH, forskolin or 8-Br-cAMP induced a marked increase of SERCA2b activity. This effect was completely abolished by H89, a specific inhibitor of cAMP-dependent protein kinase A (PKA). TSH and 8-Br-cAMP increased Ca2+ store content after both long (48 h) and short (1-2 h) treatments. CONCLUSIONS: These data suggested that TSH/cAMP acts as an important regulator of both SERCA2b expression and activity in the thyroid system, through PKA activation.     

Crystal structure of a eukaryotic zinc-dependent histone deacetylase, human HDAC8, complexed with a hydroxamic acid inhibitor

Histone deacetylases (HDACs) are a family of enzymes involved in the regulation of gene expression, DNA repair, and stress response. These processes often are altered in tumors, and HDAC inhibitors have had pronounced antitumor activity with promising results in clinical trials. Here, we report the crystal structure of human HDAC8 in complex with a hydroxamic acid inhibitor. Such a structure of a eukaryotic zinc-dependent HDAC has not be described previously. Similar to bacterial HDAC-like protein, HDAC8 folds in a single alpha/beta domain. The inhibitor and the zinc-binding sites are similar in both proteins. However, significant differences are observed in the length and structure of the loops surrounding the active site, including the presence of two potassium ions in HDAC8 structure, one of which interacts with key catalytic residues. CD data suggest a direct role of potassium in the fold stabilization of HDAC8. Knockdown of HDAC8 by RNA interference inhibits growth of human lung, colon, and cervical cancer cell lines, highlighting the importance of this HDAC subtype for tumor cell proliferation. Our findings open the way for the design and development of selective inhibitors of HDAC8 as possible antitumor agents.     

Pharmacotherapeutic options for treating brain metastases in non-small cell lung cancer

Introduction: Central nervous system (CNS) metastases represent an important cause of morbidity and mortality in non-small cell lung cancer (NSCLC) patients. Local approaches of neurosurgery (usually for single brain lesions), whole brain radiotherapy, and stereotactic radiosurgery are often withheld for the treatment of NSCLC-derived brain metastases (BMs). However, systemic treatment is consistently emerging as an option for patients with asymptomatic BMs, which could allow for delaying cranial radiotherapy at symptomatic/radiological progression.

Areas covered: Chemotherapy, monoclonal antibodies, tyrosine-kinase inhibitors (TKIs) for molecularly selected NSCLCs, such as epidermal growth factor receptor (EGFR)-mutant and anaplastic lymphoma kinase (ALK)-rearranged diseases, and immune checkpoint inhibitors are all systemic treatments that have shown activity against NSCLC-derived CNS metastases. Among these, EGFR- and ALK-TKIs will be discussed more in detail owing to their superior efficacy in this context.

Expert opinion: Up-front systemic treatment should be considered for patients with asymptomatic, multiple BMs, as recently acknowledged by the European Society of Medical Oncology guidelines. Nevertheless, it must be emphasized that the best treatment strategy for NSCLC-derived BMs has to be defined within a multidisciplinary team.     

Novel de novo heterozygous loss-of-function variants in MED13L and further delineation of the MED13L haploinsufficiency syndrome

MED13L haploinsufficiency has recently been described as responsible for syndromic intellectual disability. We planned a search for causative gene variants in seven subjects with intellectual disability and overlapping dysmorphic facial features such as bulbous nasal tip, short mouth and straight eyebrows. We found two de novo frameshift variants in MED13L, consisting in single-nucleotide deletion (c.3765delC) and duplication (c.607dupT). A de novo nonsense variant (c.4420A>T) in MED13L was detected in a further subject in the course of routine whole-exome sequencing. By analyzing the clinical data of our patients along with those recently described in the literature, we confirm that there is a common, recognizable phenotype associated with MED13L haploinsufficiency, which includes intellectual disability and a distinctive facial appearance. Congenital heart diseases are found in some subjects with various degree of severity. Our observation of cleft palate, ataxia, epilepsy and childhood leukemia observed in single cases broadens the known clinical spectrum. Haploinsufficiency for MED13L should be considered in the differential diagnosis of the 1p36 microdeletion syndrome, due to overlapping dysmorphic facial features in some patients. The introduction of massive parallel-sequencing techniques into clinical practice is expected to allow for detection of other causative point variants in MED13L. Analysis of genomic data in connection with deep clinical evaluation of patients could elucidate genetic heterogeneity of the MED13L haploinsufficiency phenotype.     

Effects of estrogen and medroxyprogesterone acetate on subpopulations of triglyceride-rich lipoproteins and high-density lipoproteins

Hormonal replacement therapy (HRT) in postmenopausal women has been shown to increase both triglyceride (TG) and high-density lipoprotein (HDL) cholesterol levels. To better understand the effects of conjugated equine estrogen (CEE) and medroxyprogesterone acetate (MPA), the 2 most commonly prescribed hormones in HRT, on the different subpopulations of TG-rich and HDL lipoproteins, we conducted a placebo-controlled, double-blind, randomized, crossover study consisting of 3 different phases in 14 postmenopausal women. The 3 phases, each 8-week long, included: (1) placebo, (2) CEE 0.625 mg/d, and (3) CEE 0.625 mg/d and MPA 2.5 mg/d. Slight and statistically nonsignificant elevations in TG levels were observed during the CEE treatment. While very-low-density lipoprotein (VLDL) cholesterol levels were not significantly affected by CEE and CEE + MPA, both HRT treatments lowered remnant lipoprotein (RLP) cholesterol (-14% and -37%, respectively). Compared with placebo, CEE caused a significant increase in HDL, HDL(2), apolipoprotein (apo) A-I, LpAI, alpha1, and prealpha1 levels (12%, 27%, 17%, 26%, 60%, and 102%, respectively). The combination therapy blunted the CEE effect on all HDL parameters, resulting in HDL, HDL(2), and LpAI levels being no longer significantly different from placebo. Apo A-I levels and alpha1, and prealpha1 levels were still significantly higher than placebo (+11%, +50%, and +112%, respectively). These results indicate that HRT has beneficial effects on RLP levels and that, while the estrogen component of HRT has a beneficial effect on the HDL subpopulations mostly associated with coronary heart disease (CHD) protection, MPA partially inhibits this effect.     

Relationships between leisure-time physical activity, obesity and disability in elderly men

BACKGROUND AND AIMS: Relationships have already been shown between leisure-time physical activity, obesity and body composition in young adults. However, this association needs to be confirmed in the elderly. The aim of this study was to investigate the relationship between leisure-time physical activity, obesity, preservation of muscle mass and disability in elderly men. METHODS: Cross-sectional analysis of a sample of 85 community-dwelling men, 68 to 79 years of age. Body mass index (BMI) was used to quantify obesity. Body composition was evaluated using Dual Energy X-ray Absorptiometry. Disability was measured using a modified version of the Activities of Daily Living scale. Leisure-time physical activity was evaluated by a validated self-administered questionnaire. RESULTS: A negative relation between obesity and weekly walking was observed. Walking less than 30 minutes per day was associated with a 2.7 greater probability of being obese (95% CI 1.1-6.7). High-intensity exercise, such as brisk walking or gardening, was inversely correlated with body fat (R = -0.296, p < 0.01) and directly correlated with appendicular skeletal mass (R = 0.238, p < 0.05). The prevalence of disability was the highest (58%) among overweight elderly subjects at the lowest tertile of exercise. Multiple logistic regression selected BMI as a positive predictor and high-intensity exercise as a negative predictor of disability. CONCLUSIONS: Our study shows that, in elderly men, leisure-time physical activity is inversely associated with body fat, BMI, and reported disability, but positively associated with appendicular fat-free mass. The highest prevalence of reported disability was observed in sedentary subjects with BMI higher than 25 kg/m2.     

Weekly docetaxel versus CMF as adjuvant chemotherapy for elderly breast cancer patients: safety data from the multicentre phase 3 randomised ELDA trial

Within an ongoing multicentre phase 3 randomised trial (ELDA, cancertrials.gov ID: NCT00331097), early breast cancer patients, 65-79 years old, with average to high risk of recurrence, are randomly assigned to receive CMF (cyclophosphamide 600 mg/m2, methotrexate 40 mg/m2, fluorouracil 600 mg/m2, days 1-8) or docetaxel (35 mg/m2 days 1-8-15), every 4 weeks. Here we report an unplanned safety analysis prompted by an amendment introducing creatinine clearance as a tool to adjust methotrexate dose. Before such change, 101 patients with a median age of 70 were randomly assigned CMF (53 patients) or docetaxel (48 patients). At least one grades 3-4 toxic event of any type was reported in 40 (75.5%) and 19 (39.6%) patients with CMF and docetaxel, respectively (p=0.0002). Grades 3-4 hematological events were observed in 37 (69.8%) vs. 4 (8.3%) cases (p<0.0001) and grades 3-4 non-hematological toxicity in 12 (22.6%) vs. 15 (31.2%) patients (p=0.11), with CMF and docetaxel, respectively. A higher incidence of anemia, neutropenia, thrombocytopenia and febrile neutropenia was reported with CMF. Constipation, mucositis, nausea and vomiting were more common with CMF; diarrhoea, abdominal pain, dysgeusia, neuropathy and liver toxicity were more frequent with docetaxel. No significant interaction was found between the occurrence of severe toxicity and baseline variables, including creatinine clearance and geriatric activity scales. In conclusion, weekly docetaxel appears to be less toxic than CMF in terms of hematological toxicity.