Blockade of VEGF-C signaling inhibits lymphatic malformations driven by oncogenic PIK3CA mutation

Lymphatic malformations (LMs) are debilitating vascular anomalies presenting with large cysts (macrocystic) or lesions that infiltrate tissues (microcystic). Cellular mechanisms underlying LM pathology are poorly understood. Here we show that the somatic PIK3CA(H1047R) mutation, resulting in constitutive activation of the p110 alpha PI3K, underlies both macrocystic and microcystic LMs in human. Using a mouse model of PIK3CA(H1047R)-driven LM, we demonstrate that both types of malformations arise due to lymphatic endothelial cell (LEC)-autonomous defects, with the developmental timing of p110 alpha activation determining the LM subtype. In the postnatal vasculature, PIK3CA(H1047R) promotes LEC migration and lymphatic hypersprouting, leading to microcystic LMs that grow progressively in a vascular endothelial growth factor C (VEGF-C)-dependent manner. Combined inhibition of VEGF-C and the PI3K downstream target mTOR using Rapamycin, but neither treatment alone, promotes regression of lesions. The best therapeutic outcome for LM is thus achieved by co-inhibition of the upstream VEGF-C/VEGFR3 and the downstream PI3K/mTOR pathways. Lymphatic malformation (LM) is a debilitating often incurable vascular disease. Using a mouse model of LM driven by a disease-causative PIK3CA mutation, the authors show that vascular growth is dependent on the upstream lymphangiogenic VEGF-C signalling, permitting effective therapeutic intervention.Peer reviewe

A Novel High-Throughput Assay for Islet Respiration Reveals Uncoupling of Rodent and Human Islets

The pancreatic beta cell is unique in its response to nutrient by increased fuel oxidation. Recent studies have demonstrated that oxygen consumption rate (OCR) may be a valuable predictor of islet quality and long term nutrient responsiveness. To date, high-throughput and user-friendly assays for islet respiration are lacking. The aim of this study was to develop such an assay and to examine bioenergetic efficiency of rodent and human islets.The XF24 respirometer platform was adapted to islets by the development of a 24-well plate specifically designed to confine islets. The islet plate generated data with low inter-well variability and enabled stable measurement of oxygen consumption for hours. The F1F0 ATP synthase blocker oligomycin was used to assess uncoupling while rotenone together with myxothiazol/antimycin was used to measure the level of non-mitochondrial respiration. The use of oligomycin in islets was validated by reversing its effect in the presence of the uncoupler FCCP. Respiratory leak averaged to 59% and 49% of basal OCR in islets from C57Bl6/J and FVB/N mice, respectively. In comparison, respiratory leak of INS-1 cells and C2C12 myotubes was measured to 38% and 23% respectively. Islets from a cohort of human donors showed a respiratory leak of 38%, significantly lower than mouse islets.The assay for islet respiration presented here provides a novel tool that can be used to study islet mitochondrial function in a relatively high-throughput manner. The data obtained in this study shows that rodent islets are less bioenergetically efficient than human islets as well as INS1 cells

Metabolites of Purine Nucleoside Phosphorylase (NP) in Serum Have the Potential to Delineate Pancreatic Adenocarcinoma

Pancreatic Adenocarcinoma (PDAC), the fourth highest cause of cancer related deaths in the United States, has the most aggressive presentation resulting in a very short median survival time for the affected patients. Early detection of PDAC is confounded by lack of specific markers that has motivated the use of high throughput molecular approaches to delineate potential biomarkers. To pursue identification of a distinct marker, this study profiled the secretory proteome in 16 PDAC, 2 carcinoma in situ (CIS) and 7 benign patients using label-free mass spectrometry coupled to 1D-SDS-PAGE and Strong Cation-Exchange Chromatography (SCX). A total of 431 proteins were detected of which 56 were found to be significantly elevated in PDAC. Included in this differential set were Parkinson disease autosomal recessive, early onset 7 (PARK 7) and Alpha Synuclein (aSyn), both of which are known to be pathognomonic to Parkinson's disease as well as metabolic enzymes like Purine Nucleoside Phosphorylase (NP) which has been exploited as therapeutic target in cancers. Tissue Microarray analysis confirmed higher expression of aSyn and NP in ductal epithelia of pancreatic tumors compared to benign ducts. Furthermore, extent of both aSyn and NP staining positively correlated with tumor stage and perineural invasion while their intensity of staining correlated with the existence of metastatic lesions in the PDAC tissues. From the biomarker perspective, NP protein levels were higher in PDAC sera and furthermore serum levels of its downstream metabolites guanosine and adenosine were able to distinguish PDAC from benign in an unsupervised hierarchical classification model. Overall, this study for the first time describes elevated levels of aSyn in PDAC as well as highlights the potential of evaluating NP protein expression and levels of its downstream metabolites to develop a multiplex panel for non-invasive detection of PDAC

Risk of imminent fracture following a previous fracture in a Swedish database study

The SummaryThis study examined the imminent risk of a future fracture within 1 and 2years following a first fracture in women aged 50years and older and assessed independent factors associated with risk of subsequent fractures. The study highlights the need to intervene rapidly after a fracture to prevent further fractures.IntroductionThis study aims to determine the imminent risk of subsequent fractures within 1 and 2years following a first fracture and to assess independent factors associated with subsequent fractures.MethodsRetrospective, observational cohort study of women aged 50years with a fragility fracture was identified from Swedish national registers. Clinical/demographic characteristics at the time of index fracture and cumulative fracture incidences up to 12 and 24months following index fracture were calculated. Risk factors for subsequent fracture were identified using multivariate regression analysis.ResultsTwo hundred forty-two thousand one hundred eight women (mean [SD] age 74 [12.5] years) were included. The cumulative subsequent fracture incidence at 12months was 7.1% (95% confidence interval [CI], 6.9-7.2) and at 24months was 12.0% (95% CI, 11.8-12.1). The rate of subsequent fractures was highest in the first month (similar to 15 fractures per 1000 patient-years) and remained steady between 4 and 24months (similar to 5 fractures/1000 patient-years). Higher age was an independent risk factor for imminent subsequent fractures (at 24months, sub-distribution hazard ratio [HR], 3.07; p<0.001 for women 80-89years [reference 50-59years]). Index vertebral fracture was a strong independent risk factor for subsequent fracture (sub-distribution HR, 2.72 versus hip fracture; p<0.001 over 12months; HR, 2.23; p<0.001 over 24months).ConclusionsOur findings highlight the need to intervene rapidly after any fragility fracture in postmenopausal women. The occurrence of a fragility fracture provides healthcare systems with a unique opportunity to intervene to reduce the increased risk of subsequent fractures

Clinical and Economic Burden of Pediatric Mild-to-Moderate Atopic Dermatitis : A Population-Based Nested Case-Control Study in Sweden

Introduction: Atopic dermatitis (AD) is a chronic, relapsing inflammatory skin condition characterized by pruritic, eczematous lesions. Recent evidence suggests that AD may be a systemic disorder, implying that management of this disease extends beyond merely controlling symptoms associated with AD. Even though this disease is highly prevalent in children and patients typically present with mild-to-moderate symptoms, the disease burden is not well established. Methods: A large, retrospective cohort study of Swedish population data was conducted to compare the clinical burden in terms of healthcare resource use and direct medical costs for pediatric mild-to-moderate (pM2M) AD patients (<= 14 years of age, N = 87,721) with matched controls. The burden of a severe AD cohort was also evaluated. Severity of AD was defined by treatment usage and systemic treatment was used as a proxy for severe AD. A robust approach was used by including any type of secondary care visits known to be more common in AD patients than in the general population; however, data for primary care visits were not available. Results: For healthcare resource use, the incidence rate ratio (pM2M AD versus reference cohort) of secondary care visits ranged from 1.56 to 2.35 during each of 5 years after AD onset (all p < 0.001), with largest differences seen in years 1-2. The average direct medical cost (SD) was euro1111 (3416) and euro524 (2446) in the pM2M AD and reference cohorts, respectively. The corresponding estimate in the severe AD cohort was euro1906 (7067). Including all secondary care visits and pharmacy-dispensed medications, the pM2M AD cohort was shown to have an additional euro118.9 million in direct medical costs over 5 years compared with the reference cohort. Conclusions: This study shows significant clinical and economic burden of pM2M AD with important secondary care resource utilization, suggesting a need for further research to increase treatment options and improve the management of these patients

Combined transcriptome and proteome profiling of the pancreatic β-cell response to palmitate unveils key pathways of β-cell lipotoxicity

BACKGROUND: Prolonged exposure to elevated free fatty acids induces β-cell failure (lipotoxicity) and contributes to the pathogenesis of type 2 diabetes. In vitro exposure of β-cells to the saturated free fatty acid palmitate is a valuable model of lipotoxicity, reproducing features of β-cell failure observed in type 2 diabetes. In order to map the β-cell response to lipotoxicity, we combined RNA-sequencing of palmitate-treated human islets with iTRAQ proteomics of insulin-secreting INS-1E cells following a time course exposure to palmitate. RESULTS: Crossing transcriptome and proteome of palmitate-treated β-cells revealed 85 upregulated and 122 downregulated genes at both transcript and protein level. Pathway analysis identified lipid metabolism, oxidative stress, amino-acid metabolism and cell cycle pathways among the most enriched palmitate-modified pathways. Palmitate induced gene expression changes compatible with increased free fatty acid mitochondrial import and β-oxidation, decreased lipogenesis and modified cholesterol transport. Palmitate modified genes regulating endoplasmic reticulum (ER) function, ER-to-Golgi transport and ER stress pathways. Furthermore, palmitate modulated cAMP/protein kinase A (PKA) signaling, inhibiting expression of PKA anchoring proteins and downregulating the GLP-1 receptor. SLC7 family amino-acid transporters were upregulated in response to palmitate but this induction did not contribute to β-cell demise. To unravel critical mediators of lipotoxicity upstream of the palmitate-modified genes, we identified overrepresented transcription factor binding sites and performed network inference analysis. These identified LXR, PPARα, FOXO1 and BACH1 as key transcription factors orchestrating the metabolic and oxidative stress responses to palmitate. CONCLUSIONS: This is the first study to combine transcriptomic and sensitive time course proteomic profiling of palmitate-exposed β-cells. Our results provide comprehensive insight into gene and protein expression changes, corroborating and expanding beyond previous findings. The identification of critical drivers and pathways of the β-cell lipotoxic response points to novel therapeutic targets for type 2 diabetes