Citations

Loss of BMP (bone morphogenic protein) signaling induces a phenotype switch of pulmonary arterial smooth muscle cells (PASMCs), which is the pathological basis of pulmonary vascular remodeling in pulmonary arterial hypertension (PAH). Here, we identified FGF12 (fibroblast growth factor 12) as a novel regulator of the BMP-induced phenotype change in PASMCs and elucidated its role in pulmonary vascular remodeling during PAH development. Using murine models of PAH and lung specimens of patients with PAH, we observed that FGF12 expression was significantly reduced in PASMCs. In human PASMCs, FGF12 expression was increased by canonical BMP signaling. FGF12 knockdown blocked the antiproliferative and prodifferentiation effect of BMP on human PASMCs, suggesting that FGF12 is required for the BMP-mediated acquisition of the quiescent and differentiated PASMC phenotype. Mechanistically, FGF12 regulated the BMP-induced phenotype change by inducing MEF2a (myocyte enhancer factor 2a) phosphorylation via p38MAPK signaling, thereby modulating the expression of MEF2a target genes involved in cell proliferation and differentiation. Furthermore, we observed that TG (transgenic) mice with smooth muscle cell–specific FGF12 overexpression were protected from chronic hypoxia–induced PAH development, pulmonary vascular remodeling, and right ventricular hypertrophy. Consistent with the in vitro data using human PASMCs, FGF12 TG mice showed increased MEF2a phosphorylation and a substantial change in MEF2a target gene expression, compared with the WT (wild type) controls. Overall, our findings demonstrate a novel BMP/FGF12/MEF2a pathway regulating the PASMC phenotype switch and suggest FGF12 as a potential target for the development of therapeutics for ameliorating pulmonary vascular remodeling in PAH.

Abstract Myocardial bridges are anatomical entities characterized by myocardium covering segments of coronary arteries. In some patients, the presence of a myocardial bridge is benign and is only incidentally found on autopsy. In other patients, however, myocardial bridges can lead to compression of the coronary artery during systolic contraction and delayed diastolic relaxation, resulting in myocardial ischemia. This ischemia in turn can lead to myocardial infarction, ventricular arrhythmias and sudden cardiac death. Myocardial bridges have also been linked to an increased incidence of atherosclerosis, which has been attributed to increased shear stress and the presence of vasoactive factors. Other studies however, demonstrated the protective roles of myocardial bridges. In this study, using systematic review and a meta‐analytical approach we investigate the prevalence and morphology of myocardial bridges in both clinical imaging and cadaveric dissections. We also discuss the pathophysiology, clinical significance, and management of these anatomical entities.

Background Ang‐(1‐12) is a primary non‐renin dependent substrate for direct tissue angiotensin II (Ang II) formation by chymase. This discovery challenges conventional thinking and explains the large residual risk of cardiovascular events in patients medicated with blockers of the renin angiotensin system (RAS). Here we report the first demonstration of circulating Ang‐(1‐12) as a biomarker of essential hypertension (EH) and cardio‐renal remodeling. Methods The cohort of patients from Olmsted County MN included 52 healthy adult volunteers (21 females), age 54 ± 8 years, and 23 essential hypertensive (EH) patients (14 females) age 61 ± 8 years with systolic blood pressure (SBP) ≥140 mm Hg prior to recruitment. Clinical examination, standardized BP measurements, and venous blood were obtained for measurements of plasma concentrations of angiotensinogen (AGT), Ang‐(1‐12), Ang II, aldosterone, renin activity, N‐terminal pro–B‐type natriuretic peptide (NT‐proBNP) and atrial and brain natriuretic peptides (ANP and BNP, respectively). All values are Means ± SD. Data were analyzed by 2‐way ANOVA for sex and hypertension. Results Plasma Ang‐(1‐12) levels in EHs [SBP: 134 ± 14 mm Hg; Ang‐(1‐12): 1,463 ± 446] were higher than normotensives [SBP: 117 ± 13 mm Hg; Ang‐(1‐12): 1,353 ± 379 fmol/mL, hypertension effect: P<0.05], irrespective of sex. Hypertension associated with increases in pulse pressure, PRA, and plasma AGT and NT‐proBNP concentrations (see Figure ). The elevation in circulating NT‐proBNP levels with hypertension was accounted for by a 4.6‐fold increase in hypertensive males (165 ± 134 pg/mL) while the 1.5‐fold rise in plasm NT‐proBNP did reach significance (134 ± 127 pg/mL, p> 0.05). Conclusions We show for the first time that Ang‐(1‐12) circulates in humans and its concentrations are elevated by chronic hypertension. We further demonstrate a sexual dimorphic pattern in hypertensives with respect to NT‐proBNP, the latter a biomarker for cardiac remodeling. Whether this represents a natriuretic system‐related compensatory mechanism, or worsening pathology, due to an elevated noncanonical RAS specific to male hypertensives remains to be studied. Further investigation to fully define the role of Ang‐(1‐12) as a cardiac disease biomarker in a larger, gender and ethnic diverse population and its relationship to hypertension and myocardial structure is warranted. Support or Funding Information Supported by grant HL‐051952 from the NHLBI of the NIH Lines are means ± SD Figure 1

Abstract Stearoyl‐CoA desaturases (SCD) are endoplasmic reticulum (ER)‐associated enzymes that catalyze the synthesis of the monounsaturated fatty acids (MUFAs). As such, SCD play important roles in maintaining the intracellular balance between saturated fatty acid (SFAs) and MUFAs. The roles of SCD in CD4 + T‐helper cell responses are currently unexplored. Here, we have found that murine and human follicular helper T (T FH ) cells express higher levels of SCD compared to non‐T FH cells. Further, the expression of SCD in T FH cells is dependent on the T FH lineage‐specification transcription factor BCL6. We found that the inhibition of SCD impaired T FH cell maintenance and shifted the balance between T FH and follicular regulatory T (T FR ) cells in the spleen. Consequently, SCD inhibition dampened germinal center B‐cell responses following influenza immunization. Mechanistically, we found that SCD inhibition led to increased ER stress and enhanced T FH cell apoptosis in vitro and in vivo. These results reveal a possible link between fatty acid metabolism and cellular and humoral responses induced by immunization or potentially, autoimmunity.

SummaryTransplant‐associated thrombotic microangiopathy (TA‐TMA) is a complication of allogeneic transplantation (allo‐HCT). The incidence and risk factors associated with TA‐TMA are not well known. A retrospective analysis from the Center for International Blood and Marrow Transplant Research (CIBMTR) was conducted including patients receiving allo‐HCT between 2008 and 2016, with the primary objective of evaluating the incidence of TA‐TMA. Secondary objectives included identification of risk factors associated with TA‐TMA, and the impact of TA‐TMA on overall survival and the need for renal replacement therapy (RRT). Among 23,665 allo‐HCT recipients, the 3‐year cumulative incidence of TA‐TMA was 3%. Variables independently‐associated with increased incidence of TA‐TMA included female sex, prior autologous transplant, primary disease (acute lymphoblastic leukaemia and severe aplastic anaemia), donor type (mismatched or unrelated donor), conditioning intensity (myeloablative), GVHD prophylaxis (sirolimus + calcineurin inhibitor), pre‐transplant kidney dysfunction and acute GVHD (time‐varying effect). TA‐TMA was associated with higher mortality (HR = 3·1, 95% Confidence Interval [CI] = 2·8–16·3) and RRT requirement (HR = 7·1, 95% CI = 5·7–311·6). This study provides epidemiologic data on TA‐TMA and its impact on transplant outcomes. Increased awareness of the risk factors will enable providers to be vigilant of this uncommon but serious transplant complication. The results will also provide benchmarking for future study designs and comparisons.

AbstractBackgroundThe 2018 Lipids in Parenteral Nutrition summit involved a panel of experts in clinical nutrition, lipid metabolism, and pharmacology, to assess the current state of knowledge and develop expert consensus statements regarding the use of intravenous lipid emulsions in various patient populations and clinical settings. The main purpose of the consensus statements is to assist healthcare professionals by providing practical guidance on common clinical questions related to the provision of lipid emulsions as part of parenteral nutrition (PN).MethodsThe summit was designed to allow interactive discussion and consensus development. The resulting consensus statements represent the collective opinion of the members of the expert panel, which was informed and supported by scientific evidence and clinical experience.ResultsThe current article summarizes the key discussion topics from the summit and provides a set of consensus statements designed to complement existing evidence‐based guidelines. Lipid emulsions are a major component of PN, serving as a condensed source of energy and essential fatty acids. In addition, lipids modulate a variety of biologic functions, including inflammatory and immune responses, coagulation, and cell signaling. A growing body of evidence suggests that lipid emulsions containing ω‐3 fatty acids from fish oil confer important clinical benefits via suppression of inflammatory mediators and activation of pathways involved in the resolution of inflammation.ConclusionsThis article provides a set of expert consensus statements to complement formal PN guideline recommendations.

PURPOSETo estimate age-specific relative and absolute cancer risks of breast cancer and to estimate risks of ovarian, pancreatic, male breast, prostate, and colorectal cancers associated with germline PALB2 pathogenic variants (PVs) because these risks have not been extensively characterized.METHODSWe analyzed data from 524 families with PALB2 PVs from 21 countries. Complex segregation analysis was used to estimate relative risks (RRs; relative to country-specific population incidences) and absolute risks of cancers. The models allowed for residual familial aggregation of breast and ovarian cancer and were adjusted for the family-specific ascertainment schemes.RESULTSWe found associations between PALB2 PVs and risk of female breast cancer (RR, 7.18; 95% CI, 5.82 to 8.85; P = 6.5 × 10−76), ovarian cancer (RR, 2.91; 95% CI, 1.40 to 6.04; P = 4.1 × 10−3), pancreatic cancer (RR, 2.37; 95% CI, 1.24 to 4.50; P = 8.7 × 10−3), and male breast cancer (RR, 7.34; 95% CI, 1.28 to 42.18; P = 2.6 × 10−2). There was no evidence for increased risks of prostate or colorectal cancer. The breast cancer RRs declined with age ( P for trend = 2.0 × 10−3). After adjusting for family ascertainment, breast cancer risk estimates on the basis of multiple case families were similar to the estimates from families ascertained through population-based studies ( P for difference = .41). On the basis of the combined data, the estimated risks to age 80 years were 53% (95% CI, 44% to 63%) for female breast cancer, 5% (95% CI, 2% to 10%) for ovarian cancer, 2%-3% (95% CI females, 1% to 4%; 95% CI males, 2% to 5%) for pancreatic cancer, and 1% (95% CI, 0.2% to 5%) for male breast cancer.CONCLUSIONThese results confirm PALB2 as a major breast cancer susceptibility gene and establish substantial associations between germline PALB2 PVs and ovarian, pancreatic, and male breast cancers. These findings will facilitate incorporation of PALB2 into risk prediction models and optimize the clinical cancer risk management of PALB2 PV carriers.

Thoracic outlet syndrome (TOS) refers to a constellation of symptoms resulting from neurovascular compression at the thoracic outlet, causing some combination of pain in the neck and upper extremity, weakness, sensory loss, paresthesia, swelling, and discoloration. Classification of TOS would depend on the anatomical structure that is compressed: venous TOS (VTOS)—compression of Subclavian vein; arterial TOS (ATOS)—compression of subclavian artery; and neurogenic TOS (NTOS)—compression of brachial plexus. Postural Orthostatic Tachycardia Syndrome (POTS) is characterized by orthostatic tachycardia that develops in the absence of orthostatic hypotension, with a symptom duration of >6 months. POTS is now known to be commonly associated with Ehlers-Danlos Syndrome (EDS), thereby raising speculation about the extent of prevalence of TOS symptoms in EDS patients. The aim of the study was to quantify the influx of patients with POTS, reporting symptoms of arm fatigue with or without numbness and tingling. The symptoms were quantified initially by conducting postural maneuvers that would reproduce the symptoms, to rule-in the possibility of TOS and further confirmed by using ultrasonography in upper limbs as the imaging modality of choice to evaluate arterial and/or venous compression. This study also looks at the presence of a concurrent diagnosis of EDS among the symptomatic patients who test positive for TOS.