👤 Frank Westermann

Fibroblast growth factor receptor 1 (FGFR1) is recurrently mutated at p.N546 in neuroblastoma. We examined whether mutant FGFR1 is an oncogenic driver, a predictive biomarker, and an actionable vulnerability in this malignancy. FGFR1 mutations at p.N546 were associated with high-risk disease and rapid tumor progression, resulting in dismal outcome for these patients. Ectopic expression of FGFR1N546K induced constitutive downstream signaling and IL-3-independent growth in Ba/F3 cells, indicating oncogene-addicted proliferation. In FGFR1N546K;MYCN transgenic mice, neuroblastoma developed within the first days of life, with fatal outcome within 3 weeks, reflecting the devastating clinical phenotypes of patients with FGFR1-mutant, high-risk neuroblastoma. Treatment with FGFR inhibitors impaired proliferation and pathway activation in FGFR1N546K-expressing Ba/F3 and patient-derived FGFR1N546K-mutant neuroblastoma cells and inhibited tumor growth in FGFR1N546K;MYCN transgenic mice and in a chemotherapy-resistant, patient-derived xenograft mouse model. In addition, partial regression of FGFR1N546K-mutant tumor lesions occurred upon treatment with the FGFR inhibitor futibatinib and low-intensity chemotherapy in a patient with refractory neuroblastoma. Together, our data demonstrate that FGFR1N546K is a strong oncogenic driver in neuroblastoma associated with failure of current standard chemotherapy and suggest potential clinical benefit of FGFR-directed therapies in patients with high-risk mutant FGFR1. Show less

OxPL-apoB (oxidized phospholipids [OxPL] on apoB-100), which include OxPL present on Lp(a) (lipoprotein[a]), are associated with higher cardiovascular risk. Experimental studies suggest that OxPL may influence platelet function. This observational study assessed the association of OxPL-apoB with intrinsic and on‑clopidogrel platelet reactivity and long-term cardiovascular events in patients undergoing coronary angiography with or without percutaneous coronary intervention in 2040 patients in the EXCELSIOR trial (Impact of Extent of Clopidogrel-Induced Platelet Inhibition During Elective Stent Implantation on Clinical Event Rate). The association of OxPL-apoB to expression of CD62P, CD41, or PAC-1 levels and intrinsic and on-clopidogrel platelet reactivity to collagen and ADP was determined. The relationship of OxPL-apoB and Lp(a) to myocardial infarction-free survival and all-cause mortality at a median of 7 years was assessed using Cox regression models. Elevated levels of OxPL-apoB were associated with the severity of coronary obstruction, and higher prevalence of prior myocardial infarction, percutaneous coronary intervention, and coronary artery bypass graft surgery. No significant associations were present between OxPL-apoB and intrinsic or on-clopidogrel platelet reactivity or activation of platelet receptors. Analyzed individually in separate multivariable models, both OxPL-apoB (hazard ratio, 1.022 [95% CI, 1.005-1.040]; In patients undergoing coronary angiography with or without percutaneous coronary intervention, OxPL-apoB was not associated with intrinsic and on-clopidogrel platelet reactivity mediated by collagen or ADP. The association of OxPL-apoB and Lp(a) suggests that the accumulation of OxPL on Lp(a) may be a key determinant of long-term cardiovascular outcomes. URL: https://www.clinicaltrials.gov; Unique identifier: NCT00457236. Show less

The repertoire of adhesion receptors and ligands is supported by molecules, which are primarily recognized for their roles in immunity. We have recently shown that the co-stimulatory molecule CD40 ligand (CD154/CD40L) is pro-atherogenic and serves as an adhesive ligand for cells expressing the integrin Mac-1 (CD11b/CD18). Here, we studied the role of endothelial CD40L in several models of cardiovascular inflammation. We generated mice with an endothelial cell-specific deficiency of CD40L, Bmx-Cre In this functional validation study, we demonstrate that endothelial cell-expressed CD40L serves as an adhesion molecule in different models of acute inflammation in the aortic, peritoneal, mesenteric, and coronary vasculature. CD40L may therefore represent a promising therapeutic target at the interface of adaptive immunity and myeloid inflammation. Show less

Elevated Lipoprotein(a) Lp(a) levels are associated with coronary atherosclerosis as detected by cardiac computed tomography angiography (CCTA). However, quantitative data including coronary plaque volumes and characteristics are scarce. The current study evaluated the sex-specific correlations between (Lp(a)) levels and the extent and composition of coronary stenosis and plaques. 1,946 patients undergoing CCTA (third-generation dual-source scanner) for suspected coronary artery disease were included whose Lp(a) levels were available. Lp(a) values ≥ 125 nmol/L were classified as high. High Lp(a) levels were observed in 336 patients, who had greater maximum degree of stenosis (49.5 ± 26.4% vs. 43.5 ± 27.6%, P = 0.002), mainly as a result of the pronounced difference in males (53.8 ± 26.0% vs. 46.2 ± 26.8%, P = 0.001). A strong correlation between higher Lp(a) values and high-risk plaque features was noted in the overall cohort (odds ratio [OR]: 1.645; 95% confidence interval [CI]: 1.011 to 2.593; P = 0.037), independent of age and LDL-cholesterol values. In males, high Lp(a) levels were associated with greater total plaque volumes (118.1 [IQR 18.3-284.4] vs. 83.2 [IQR 11.8-226.3] mm Our study identifies novel sex-specific correlations between Lp(a) levels and coronary plaque characteristics. High Lp(a) levels in men seems to be associated with increased fibrotic plaque volumes and may contribute to greater total plaque burden and high-risk plaque features. Show less

Lysosomes are implicated in a wide spectrum of human diseases, including monogenic lysosomal storage disorders (LSDs), age-associated neurodegeneration, and cancer. Profiling lysosomal content using tag-based lysosomal immunoprecipitation (LysoTagIP) in cell and animal models has substantially moved the field forward, but studying lysosomal dysfunction in patients remains challenging. Here, we report the development of the 'tagless LysoIP' method, designed to enable the rapid enrichment of lysosomes, via immunoprecipitation, using the endogenous integral lysosomal membrane protein TMEM192, directly from clinical samples and human cell lines (e.g., induced pluripotent stem cell-derived neurons). Isolated lysosomes were intact and suitable for subsequent multimodal omics analyses. To validate our approach, we applied the tagless LysoIP to enrich lysosomes from peripheral blood mononuclear cells derived from fresh blood of healthy donors and patients with CLN3 disease, an autosomal recessive neurodegenerative LSD. Metabolic profiling of isolated lysosomes revealed massive accumulation of glycerophosphodiesters (GPDs) in patients' lysosomes. Interestingly, a patient with a milder phenotype and genotype displayed lower accumulation of lysosomal GPDs, consistent with their potential role as disease biomarkers. Altogether, the tagless LysoIP provides a framework to study native lysosomes from patient samples, identify disease biomarkers, and discover human-relevant disease mechanisms. Show less

Hypertrophic cardiomyopathy (HCM) is the most common cardiac genetic disorder caused by sarcomeric gene variants and associated with left ventricular hypertrophy and diastolic dysfunction. The role of the microtubule network has recently gained interest with the findings that microtubule detyrosination (dTyr-MT) is markedly elevated in heart failure. Acute reduction of dTyr-MT by inhibition of the detyrosinase (VASH [vasohibin]/SVBP [small VASH-binding protein] complex) or activation of the tyrosinase (TTL [tubulin tyrosine ligase]) markedly improved contractility and reduced stiffness in human failing cardiomyocytes and thus posed a new perspective for HCM treatment. In this study, we tested the impact of chronic tubulin tyrosination in an HCM mouse model ( Adeno-associated virus serotype 9-mediated TTL transfer was applied in neonatal wild-type rodents, in 3-week-old knock-in mice, and in HCM human induced pluripotent stem cell-derived cardiomyocytes. We show (1) TTL for 6 weeks dose dependently reduced dTyr-MT and improved contractility without affecting cytosolic calcium transients in wild-type cardiomyocytes; (2) TTL for 12 weeks reduced the abundance of dTyr-MT in the myocardium, improved diastolic filling, compliance, cardiac output, and stroke volume in knock-in mice; (3) TTL for 10 days normalized cell area in HCM human induced pluripotent stem cell-derived cardiomyocytes; (4) TTL overexpression activated transcription of tubulins and other cytoskeleton components but did not significantly impact the proteome in knock-in mice; (5) SVBP-deficient EHTs exhibited reduced dTyr-MT levels, higher force, and faster relaxation than TTL-deficient and wild-type EHTs. RNA sequencing and mass spectrometry analysis revealed distinct enrichment of cardiomyocyte components and pathways in SVBP-deficient versus TTL-deficient EHTs. This study provides the first proof of concept that chronic activation of tubulin tyrosination in HCM mice and in human EHTs improves heart function and holds promise for targeting the nonsarcomeric cytoskeleton in heart disease. Show less