Exploring the Role of Circular RNA in Bone Biology: A Comprehensive Review.

Circular RNAs (circRNAs) have emerged as pivotal regulators of gene expression with diverse roles in various biological processes. In recent years, research into circRNAs' involvement in bone biology has gained significant attention, unveiling their potential as novel regulators and biomarkers in bone-related disorders and diseases. CircRNAs, characterized by their closed-loop structure, exhibit stability and resistance to degradation, underscoring their functional significance. In bone tissue, circRNAs are involved in critical processes such as osteogenic differentiation, osteoclastogenesis, and bone remodeling through intricate molecular mechanisms including microRNA regulation. Dysregulated circRNAs are associated with various bone disorders, suggesting their potential as diagnostic and prognostic biomarkers. The therapeutic targeting of these circRNAs holds promise for addressing bone-related conditions, offering new perspectives for precision medicine. Thus, circRNAs constitute integral components of bone regulatory networks, impacting both physiological bone homeostasis and pathological conditions. This review provides a comprehensive overview of circRNAs in bone biology, emphasizing their regulatory mechanisms, functional implications, and therapeutic potential.

Clinical Presentation, Diagnosis, and Management of Hyperinsulinemic Hypoglycemia in Adults: A Single-center Experience.

INTRODUCTION: Hyperinsulinemic Hypoglycemia (HH) is a rare condition characterized by inappropriately elevated insulin levels in the presence of low glucose levels. A proper diagnostic framework is fundamental to avoid patients undergoing unnecessary diagnostic and therapeutic invasive procedures. OBJECTIVE: The study aimed to assess the clinical presentation, diagnostic work-up, and treatment of a single-center cohort of patients affected by HH. METHODS: We conducted a retrospective analysis of data collected from January 2000-2023. RESULTS: Our study included 104 patients: 81 (58% F) affected by insulinoma, 11 (91% F) by autoimmune hypoglycemia, 7 (71% M) by post-gastric surgery hypoglycemia, and 5 (80% F) by factitious hypoglycemia. HH was more frequent in females (63 F vs. 41 M, p-value 0.039). The median age at diagnosis was lower in insulinoma than in the autoimmune group (52.7 vs. 63.7 y, p < 0.001). During the hypoglycemic event, insulin and C-peptide levels were significantly higher in autoimmune hypoglycemia than in insulinoma (insulin 324.6 vs. 36.4 µU/ml, p-value 0.033; C-peptide 14.25 vs. 3.99 ng/ml, p-value 0.003). Specifically, C-peptide levels <9.6 ng/ml and insulin levels <75 µU/ml exhibited 97.3% vs. 93.4% sensitivity and 80% vs. 90% specificity for insulinoma diagnosis, respectively. Regarding insulinoma, the sensitivity of localizing imaging was 88% for Endoscopic Ultrasound (EUS), 86% for Magnetic Resonance Imaging (MRI), 82% for Computed Tomography (CT) scan, 52% for nuclear imaging, and 100% for angiography with the Doppman test. Among insulinoma patients, 79% received surgical treatment while 4% radiofrequency ablation. Symptomatic remission occurred in 100% of cases. CONCLUSION: We have confirmed insulinoma as the primary cause of HH. The autoimmune form should be suspected when insulin and C-peptide levels are markedly elevated.

Incidence and clinical progression of asymptomatic peripherally inserted central catheter-related thrombosis in solid neoplasm patients: ultrasound insights from a prospective cohort study.

Background: Managing central venous catheters in patients with neoplasms is challenging, and peripherally inserted central catheter PORT (PICC-PORT) has emerged as a promising option for safety and efficacy. However, understanding the clinical progression of catheter-related thrombosis (CRT) in cancer patients with central venous catheters remains limited, especially in certain neoplasm types associated with a higher risk of venous thrombosis. Objectives: This study aims to assess the effectiveness of ultrasound-guided management in detecting and treating asymptomatic CRT in cancer patients with PICC. Methods: In this prospective cohort study of 120 patients with solid neoplasms receiving chemotherapy, we investigated the incidence of isolated upper-extremity superficial vein thrombosis, upper-extremity deep vein thrombosis, and fibrin sheath formation through ultrasound follow-up at 30 and 90 days after catheter insertion. We analyzed risk factors associated with CRT and compared incidence rates between PICC-PORT and traditional PICC. Results: Among the cohort, 69 patients (57.5%) had high-risk thromboembolic neoplasm, and 31 cases (25.8%) of CRT were observed, mostly within 30 days, with only 7 cases (22.6%) showing symptoms. Traditional PICC use (odds ratio, 5.86; 95% CI, 1.14-30) and high-risk thromboembolic neoplasm (odds ratio, 4.46; 95% CI, 1.26-15.81) were identified as independent risk factors for CRT. Conclusion: The majority of CRT present asymptomatically within the first 30 days of venous catheter insertion in patients with solid neoplasms. Ultrasound follow-up is valuable for detecting asymptomatic CRT. The risk of CRT was lower with PICC-PORT than with PICC. Additionally, the risk of CRT was found to be higher in patients with high-risk thromboembolic neoplasms. It is crucial for larger studies to confirm the utility of treating asymptomatic thromboses and isolated superficial thrombosis.

Unraveling the Connection: Visceral Adipose Tissue and Vitamin D Levels in Obesity.

Vitamin D deficiency and insufficiency are widespread on a global scale, with multiple factors playing a role in their development, such as limited exposure to sunlight, inadequate dietary consumption, as well as obesity and abdominal fat accumulation. Abdominal obesity, assessed with waist circumference (WC), is associated with metabolic syndrome and has been linked to low vitamin D levels. This study aimed to investigate the relationship between visceral adipose tissue (VAT) and vitamin D levels, particularly examining the potential threshold for vitamin D storage and sequestration using adipose tissue. The study was conducted between 2020 and 2022 with 58 patients from an internal medicine outpatient department. Patients with certain medical conditions and those taking medications affecting bone metabolism were excluded. Blood samples were collected at baseline and after 6 months of monthly cholecalciferol supplementation. Ultrasonography was used to evaluate adipose tissue measurements, including subcutaneous adipose tissue thickness, VAT, preperitoneal adipose tissue (PPAT), and prerenal adipose tissue (PRAT). Anthropometric measures such as the waist-to-hip ratio and waist-to-height ratio were also assessed. The results showed that all subjects had significant hypovitaminosis D at baseline. After 6 months of supplementation, the mean increase in vitamin D levels was 9.6 ng/mL, with 55.2% of subjects becoming deficient. The study revealed a significant correlation between follow-up vitamin D levels and waist circumference, hip circumference, and VAT. VAT exhibited a strong correlation not only with vitamin D levels but also with waist circumference. When analyzing gender differences, males showed a higher weight and waist-to-hip ratio, while females had higher body adiposity indexes and subcutaneous adipose tissue measurements. In conclusion, this study highlights the relationship between VAT and vitamin D levels, emphasizing the potential role of adipose tissue in vitamin D availability. Waist circumference was identified as a surrogate measure for VAT evaluation. Furthermore, the study showed variations in vitamin D response to supplementation between genders, with a higher percentage of males reaching normal vitamin D levels. Predictive factors for vitamin D levels differed between genders, with waist circumference being a significant predictor in males and body adiposity index in females.

DOAC in the treatment of cancer-associated venous thromboembolism: a retrospective cohort study beyond the guidelines.

BACKGROUND: The emerging use of direct oral anticoagulants (DOAC) in the management of cancer-associated venous thromboembolism (CAT) is significantly improving therapeutic adherence and quality of life. Despite this, many conditions can restrict the therapeutic index of these drugs. For all these reasons the latest guidelines recommend the use of heparins in the treatment of CAT as the preferred treatment in some clinical settings. OBJECTIVES: We evaluated the efficacy and the safety of DOAC, in terms of recurrent venous thromboembolism (VTE) and major bleeding (MB), as a composite primary outcome. Mortality and clinically relevant non-major bleeding (CRNMB) were evaluated as secondary outcomes. METHODS: We performed a retrospective study on 209 patients to compare the effects of DOAC versus heparins for the treatment of CAT. 127 patients with a high bleeding risk neoplasia were enrolled. RESULTS: A primary-outcome event occurred in 11.3% of patients treated with heparins and in 10.5% treated with DOAC (Relative Risk 0.92; 95% CI 0.42-2.01, p = 0.84). Recurrent VTE occurred in 6.1% in the heparins group and in 8.4% in the DOAC group (RR 1.37; 95% CI 0.51-3.64, p = 0.52). MB occurred in 5.2% in the heparins group and in 2.1% in the DOAC group (RR 0.40; 95% CI 0.08-1.93, p = 0.25). CONCLUSIONS: DOAC seem to be as effective and safe as heparins in the treatment of CAT. Most bleeding events occurred in patients with high-risk bleeding neoplasms regardless of the type of anticoagulant. Considering the characteristics and satisfaction of patients using DOAC in this setting, this approach should be considered as a first choice.

Effects of a 4400 km ultra-cycling non-competitive race and related training on body composition and circulating progenitors differentiation.

BACKGROUND: NorthCape4000 (NC4000) is the most participated ultra-endurance cycling race. Eight healthy male Caucasian amateur cyclists were evaluated: (a) before starting the preparation period; (b) in the week preceding NC4000 (after the training period); (c) after NC4000 race, with the aim to identify the effects of ultra-cycling on body composition, aerobic capacity and biochemical parameters as well as on the differentiation of progenitor cells. METHODS: Bioelectrical impedance analysis (BIA) and dual energy x-ray absorptiometry (DEXA) assessed body composition; cardiopulmonary exercise test (CPET) evaluated aerobic capacity. Differentiation of circulating progenitor cells was evaluated by analyzing the modulation in the expression of relevant transcription factors. In addition, in vitro experiments were performed to investigate the effects of sera of NC4000 participants on adipogenesis and myogenesis. The effects of NC4000 sera on Sestrins and Sirtuin modulation and the promotion of brown adipogenesis in progenitor cells was investigated as well. Two-tailed Student's paired-test was used to perform statistical analyses. RESULTS: We observed fat mass decrease after training as well as after NC4000 performance; we also recorded that vitamin D and lipid profiles were affected by ultra-cycling. In addition, our findings demonstrated that post-NC4000 participant's pooled sera exerted a positive effect in stimulating myogenesis and in inducing brown adipogenesis in progenitor cells. CONCLUSIONS: The training program and Ultra-cycling lead to beneficial effects on body composition and biochemical lipid parameters, as well as changes in differentiation of progenitor cells, with significant increases in brown adipogenesis and in MYOD levels.

Fisetin: An Integrated Approach to Identify a Strategy Promoting Osteogenesis.

Flavonoids may modulate the bone formation process. Among flavonoids, fisetin is known to counteract tumor growth, osteoarthritis, and rheumatoid arthritis. In addition, fisetin prevents inflammation-induced bone loss. In order to evaluate its favorable use in osteogenesis, we assayed fisetin supplementation in both in vitro and in vivo models and gathered information on nanoparticle-mediated delivery of fisetin in vitro and in a microfluidic system. Real-time RT-PCR, Western blotting, and nanoparticle synthesis were performed to evaluate the effects of fisetin in vitro, in the zebrafish model, and in ex vivo samples. Our results demonstrated that fisetin at 2.5 µM concentration promotes bone formation in vitro and mineralization in the zebrafish model. In addition, we found that fisetin stimulates osteoblast maturation in cell cultures obtained from cleidocranial dysplasia patients. Remarkably, PLGA nanoparticles increased fisetin stability and, consequently, its stimulating effects on RUNX2 and its downstream gene SP7 expression. Therefore, our findings demonstrated the positive effects of fisetin on osteogenesis and suggest that patients affected by skeletal diseases, both of genetic and metabolic origins, may actually benefit from fisetin supplementation.

Physical Activity Modulates miRNAs Levels and Enhances MYOD Expression in Myoblasts.

Stem cells functions are regulated by different factors and non-conding RNAs, such as microRNA. MiRNAsplay an important role in modulating the expression of genes involved in the commitment and differentiation of progenitor cells. MiRNAs are post transcriptional regulators which may be modulated by physical exercise. MiRNAs, by regulating different signaling pathways, play an important role in myogenesis as well as in muscle activity. MiRNAs quantification may be considered for evaluating physical performance or muscle recovery. With the aim to identify specific miRNAs potentially involved in myogenesis and modulated by physical activity, we investigated miRNAs expression following physical performance in Peripheral Blood Mononuclear Cells (PBMCs) and in sera of half marathon (HM) runnners. The effect of runners sera on Myogenesis in in vitro cellular models was also explored. Therefore, we performed Microarray Analysis and Real Time PCR assays, as well as in vitro cell cultures analysis to investigate myogenic differentiation. Our data demonstrated gender-specific expression patterns of PBMC miRNAs before physical performance. In particular, miR223-3p, miR26b-5p, miR150-5p and miR15-5p expression was higher, while miR7a-5p and miR7i-5p expression was lower in females compared to males. After HM, miR152-3p, miR143-3p, miR27a-3p levels increased while miR30b-3p decreased in both females and males: circulating miRNAs mirrored these modulations. Furthermore, we also observed that the addition of post-HM participants sera to cell cultures exerted a positive effect in stimulating myogenesis. In conclusion, our data suggest that physical activity induces the modulation of myogenesis-associated miRNAs in bothfemales and males, despite the gender-associated different expression of certain miRNAs, Noteworthy, these findings might be useful for evaluating potential targets for microRNA based-therapies in diseases affecting the myogenic stem cells population.

Modulation of miR-204 Expression during Chondrogenesis.

RUNX2 and SOX9 are two pivotal transcriptional regulators of chondrogenesis. It has been demonstrated that RUNX2 and SOX9 physically interact; RUNX2 transactivation may be inhibited by SOX9. In addition, RUNX2 exerts reciprocal inhibition on SOX9 transactivity. Epigenetic control of gene expression plays a major role in the alternative differentiation fates of stem cells; in particular, it has been reported that SOX9 can promote the expression of miRNA (miR)-204. Our aim was therefore to investigate the miR-204-5p role during chondrogenesis and to identify the relationship between this miR and the transcription factors plus downstream genes involved in chondrogenic commitment and differentiation. To evaluate the role of miR-204 in chondrogenesis, we performed in vitro transfection experiments by using Mesenchymal Stem Cells (MSCs). We also evaluated miR-204-5p expression in zebrafish models (adults and larvae). By silencing miR-204 during the early differentiation phase, we observed the upregulation of SOX9 and chondrogenic related genes compared to controls. In addition, we observed the upregulation of COL1A1 (a RUNX2 downstream gene), whereas RUNX2 expression of RUNX2 was slightly affected compared to controls. However, RUNX2 protein levels increased in miR-204-silenced cells. The positive effects of miR204 silencing on osteogenic differentiation were also observed in the intermediate phase of osteogenic differentiation. On the contrary, chondrocytes' maturation was considerably affected by miR-204 downregulation. In conclusion, our results suggest that miR-204 negatively regulates the osteochondrogenic commitment of MSCs, while it positively regulates chondrocytes' maturation.

Lysophosphatidylcholine and carotid intima-media thickness in young smokers: a role for oxidized LDL-induced expression of PBMC lipoprotein-associated phospholipase A2?

BACKGROUND: Although cigarette smoking has been associated with carotid intima-media thickness (CIMT) the mechanisms are yet not completely known. Lysophosphatidylcholine (lysoPC), a main product of lipoprotein-associated phospholipase A2 (Lp-PLA2) activity, appears to be a major determinant of the pro-atherogenic properties of oxidized LDL (oxLDL) and to induce proteoglycan synthesis, a main player in intimal thickening. In this study we assessed whether cigarette smoking-induced oxidative stress may influence plasma Lp-PLA2 and lysoPC and Lp-PLA2 expression in peripheral blood mononuclear cells (PBMC), as well as the relationship between lysoPC and CIMT. METHODS/RESULTS: 45 healthy smokers and 45 age and sex-matched subjects participated in this study. Smokers, compared to non-smokers, showed increased plasma concentrations of oxLDL, Lp-PLA2 and lysoPC together with up-regulation of Lp-PLA2 (mRNA and protein) expression in PBMC (P<0.001). Plasma Lp-PLA2 positively correlated with both lysoPC (r=0.639, P<0.001) and PBMC mRNA Lp-PLA2 (r=0.484, P<0.001) in all subjects. Moreover CIMT that was higher in smokers (P<0.001), positively correlated with lysoPC (r=0.55, P<0.001). Then in in vitro study we demonstrated that both oxLDL (at concentrations similar to those found in smoker's serum) and oxidized phospholipids contained in oxLDL, were able to up-regulate mRNA Lp-PLA2 in PBMC. This effect was likely due, at least in part, to the enrichment in oxidized phospholipids found in PBMC after exposure to oxLDL. Our results also showed that in human aortic smooth muscle cells lysoPC, at concentrations similar to those found in smokers, increased the expression of biglycan and versican, two main proteoglycans. CONCLUSIONS: In smokers a further effect of raised oxidative stress is the up-regulation of Lp-PLA2 expression in PBMC with subsequent increase of plasma Lp-PLA2 and lysoPC. Moreover the correlation between lysoPC and CIMT together with the finding that lysoPC up-regulates proteoglycan synthesis suggests that lysoPC may be a link between smoking and intimal thickening.

Serum oxidative stress-induced repression of Nrf2 and GSH depletion: a mechanism potentially involved in endothelial dysfunction of young smokers.

BACKGROUND: Although oxidative stress plays a major role in endothelial dysfunction (ED), the role of glutathione (GSH), of nuclear erythroid-related factor 2 (Nrf2) and of related antioxidant genes (ARE) are yet unknown. In this study we combined an in vivo with an in vitro model to assess whether cigarette smoking affects flow-mediated vasodilation (FMD), GSH concentrations and the Nrf2/ARE pathway in human umbilical vein endothelial cells (HUVECs). METHODS AND RESULTS: 52 healthy subjects (26 non-smokers and 26 heavy smokers) were enrolled in this study. In smokers we demonstrated increased oxidative stress, i.e., reduced concentrations of GSH and increased concentrations of oxidation products of the phospholipid 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphorylcholine (oxPAPC) in serum and in peripheral blood mononuclear cells (PBMC), used as in vivo surrogates of endothelial cells. Moreover we showed impairment of FMD in smokers and a positive correlation with the concentration of GSH in PBMC of all subjects. In HUVECs exposed to smokers' serum but not to non-smokers' serum we found that oxidative stress increased, whereas nitric oxide and GSH concentrations decreased; interestingly the expression of Nrf2, of heme oxygenase-1 (HO-1) and of glutamate-cysteine ligase catalytic (GCLC) subunit, the rate-limiting step of synthesis of GSH, was decreased. To test the hypothesis that the increased oxidative stress in smokers may have a causal role in the repression of Nrf2/ARE pathway, we exposed HUVECs to increasing concentrations of oxPAPC and found that at the highest concentration (similar to that found in smokers' serum) the expression of Nrf2/ARE pathway was reduced. The knockdown of Nrf2 was associated to a significant reduction of HO-1 and GCLC expression induced by oxPAPC in ECs. CONCLUSIONS: In young smokers with ED a novel further consequence of increased oxidative stress is a repression of Nrf2/ARE pathway leading to GSH depletion.

Cigarette smoking blocks the protective expression of Nrf2/ARE pathway in peripheral mononuclear cells of young heavy smokers favouring inflammation.

Cigarette smoking is an important risk factor for atherosclerosis, a chronic inflammatory disease. However the underlying factors of this effect are unclear. It has been hypothesized that water-soluble components of cigarette smoke can directly promote oxidative stress in vasculature and blood cells. Aim of this study was to study the relationship between oxidative stress and inflammation in a group of young smokers. To do this we evaluated: 1) the oxidation products of phospholipids (oxPAPC) in peripheral blood mononuclear cells (PBMC); 2) their role in causing PBMC reactive oxygen species (ROS) generation and changes in GSH; 3) the expression of the transcription factor NF-E2-related factor 2 (Nrf2) and of related antioxidant genes (ARE); 4) the activation of NF-kB and C-reactive protein (CRP) values. We studied 90 healthy volunteers: 32 non-smokers, 32 moderate smokers (5-10 cigarettes/day) and 26 heavy smokers (25-40 cigarettes/day). OxPAPC and p47phox expression, that reasonably reflects NADPH oxidase activity, were higher in moderate smokers and heavy smokers than in non-smokers (p<0.01), the highest values being in heavy smokers (p<0.01). In in vitro studies oxPAPC increased ROS generation via NADPH oxidase activation. GSH in PBMC and plasma was lower in moderate smokers and heavy smokers than in non-smokers (p<0.01), the lowest values being in heavy smokers (p<0.01). Nrf2 expression in PBMC was higher in moderate smokers than in non-smokers (p<0.01), but not in heavy smokers, who had the highest levels of NF-kB and CRP (p<0.01). In in vitro studies oxPAPC dose-dependently increased NF-kB activation, whereas at the highest concentrations Nrf2 expression was repressed. The small interference (si) RNA-mediated knockdown of NF-kappaB/p65 increased about three times the expression of Nrf2 stimulated with oxPAPC. Cigarette smoke promotes oxPAPC formation and oxidative stress in PBMC. This may cause the activation of NF-kB that in turn may participate in the negative regulation of Nrf2/ARE pathway favouring inflammation.

Nebivolol treatment reduces serum levels of asymmetric dimethylarginine and improves endothelial dysfunction in essential hypertensive patients.

BACKGROUND: This study was conducted to evaluate (i) the effect of nebivolol, a selective beta1-adrenergic receptor antagonist, on plasma concentration of asymmetric dimethylarginine (ADMA) and on flow-mediated dilation (FMD) in essential hypertensive patients; (ii) the effect of serum derived from the treated hypertensive patients on ADMA and on dimethylarginine dimethylaminohydrolase 2 (DDAH2), the enzyme that selectively degrades ADMA, in human umbilical vein endothelial cells (HUVECs). METHODS: Forty healthy subjects and 40 matched essential hypertensive patients treated with atenolol and nebivolol according to a double-blind, randomized design participated in the study. Evaluation of brachial artery (BA) reactivity was performed by a longitudinal B-mode scan of the right BA. ADMA and L-arginine were measured by high-performance liquid chromatography. DDAH2 expression and endothelial nitric oxide synthase activity (eNOS) were also evaluated in HUVECs. RESULTS: ADMA levels were significantly decreased and FMD increased only in patients receiving nebivolol (P < 0.01). Furthermore, in nebivolol group, we found a significant correlation between changes in ADMA levels and changes in FMD (P < 0.01). Sera derived from patients treated with nebivolol but not with atenolol decreased ADMA and increased DDAH2 expression and eNOS activity (P < 0.001) in HUVECs. CONCLUSIONS: The results of this study demonstrate that the improvement of endothelial dysfunction induced by nebivolol in hypertensive patients may be related to its effect on circulating ADMA levels. Although the mechanism by which nebivolol reduces circulating ADMA in hypertensive patients remains unclear, our ex vivo results suggest that the upregulation of DDAH2 expression may have a role.

Effects of nebivolol on endothelial gene expression during oxidative stress in human umbilical vein endothelial cells.

The endothelium plays a key role in the development of atherogenesis and its inflammatory and proliferative status influences the progression of atherosclerosis. The aim of this study is to compare the effects of two beta blockers such as nebivolol and atenolol on gene expression in human umbilical vein endothelial cells (HUVECs) following an oxidant stimulus. HUVECs were incubated with nebivolol or atenolol (10 micromol/L) for 24 hours and oxidative stress was induced by the addition of oxidized (ox)-LDL. Ox-LDL upregulated adhesion molecules (ICAM-1, ICAM-2, ICAM-3, E-selectin, and P-selectin); proteins linked to inflammation (IL-6 and TNFalpha), thrombotic state (tissue factor, PAI-1 and uPA), hypertension such as endothelin-1 (ET-1), and vascular remodeling such as metalloproteinases (MMP-2, MMP-9) and protease inhibitor (TIMP-1). The exposure of HUVECs to nebivolol, but not to atenolol, reduced these genes upregulated by oxidative stress both in terms of protein and RNA expression. The known antioxidant properties of the third generation beta blocker nebivolol seem to account to the observed differences seen when compared to atenolol and support the specific potential protective role of this beta blocker on the expression of a number of genes involved in the initiation and progression of atherosclerosis.