Norepinephrine induces vascular endothelial growth factor gene expression in brown adipocytes through a beta -adrenoreceptor/cAMP/protein kinase A pathway involving Src but independently of Erk1/2

Increased β2-adrenergic signaling promotes fracture healing through callus neovascularization in mice

Traumatic brain injury (TBI) leads to skeletal changes, including bone loss in the unfractured skeleton, and paradoxically accelerates healing of bone fractures; however, the mechanisms remain unclear. TBI is associated with a hyperadrenergic state characterized by increased norepinephrine release. Here, we identified the β2-adrenergic receptor (ADRB2) as a mediator of skeletal changes in response to increased norepinephrine. In a murine model of femoral osteotomy combined with cortical impact brain injury, TBI was associated with ADRB2-dependent enhanced fracture healing compared with osteotomy alone. In the unfractured 12-week-old mouse skeleton, ADRB2 was required for TBI-induced decrease in bone formation and increased bone resorption. Adult 30-week-old mice had higher bone concentrations of norepinephrine, and ADRB2 expression was associated with decreased bone volume in the unfractured skeleton and better fracture healing in the injured skeleton. Norepinephrine stimulated expression of vascular endothelial growth factor A and calcitonin gene-related peptide-α (αCGRP) in periosteal cells through ADRB2, promoting formation of osteogenic type-H vessels in the fracture callus. Both ADRB2 and αCGRP were required for the beneficial effect of TBI on bone repair. Adult mice deficient in ADRB2 without TBI developed fracture nonunion despite high bone formation in uninjured bone. Blocking ADRB2 with propranolol impaired fracture healing in mice, whereas the ADRB2 agonist formoterol promoted fracture healing by regulating callus neovascularization. A retrospective cohort analysis of 72 patients with long bone fractures indicated improved callus formation in 36 patients treated with intravenous norepinephrine. These findings suggest that ADRB2 is a potential therapeutic target for promoting bone healing.

The role of ischaemia-reperfusion injury and liver regeneration in hepatic tumour recurrence

The risk of cancer recurrence after liver surgery mainly depends on tumour biology, but preclinical and clinical evidence suggests that the degree of perioperative liver injury plays a role in creating a favourable microenvironment for tumour cell engraftment or proliferation of dormant micro-metastases. Understanding the contribution of perioperative liver injury to tumour recurrence is imperative, as these pathways are potentially actionable. In this review, we examine the key mechanisms of perioperative liver injury, which comprise mechanical handling and surgical stress, ischaemia-reperfusion injury, and parenchymal loss leading to liver regeneration. We explore how these processes can trigger downstream cascades leading to the activation of the immune system and the pro-inflammatory response, cellular proliferation, angiogenesis, anti-apoptotic signals, and release of circulating tumour cells. Finally, we discuss the novel therapies under investigation to decrease ischaemia-reperfusion injury and increase regeneration after liver surgery, including pharmaceutical agents, inflow modulation, and machine perfusion.

Increased beta2-adrenergic signaling is a targetable stimulus essential for bone healing by promoting callus neovascularization

Traumatic brain injury (TBI) is associated with a hyperadrenergic state and paradoxically causes systemic bone loss while accelerating fracture healing. Here, we identify the beta2-adrenergic receptor (Adrb2) as a central mediator of these skeletal manifestations. While the negative effects of TBI on the unfractured skeleton can be explained by the established impact of Adrb2 signaling on bone formation, Adrb2 promotes neovascularization of the fracture callus under conditions of high sympathetic tone, including TBI and advanced age. Mechanistically, norepinephrine stimulates the expression of Vegfa and Cgrp primarily in periosteal cells via Adrb2, both of which synergistically promote the formation of osteogenic type-H vessels in the fracture callus. Accordingly, the beneficial effect of TBI on bone repair is abolished in mice lacking Adrb2 or Cgrp, and aged Adrb2-deficient mice without TBI develop fracture nonunions despite high bone formation in uninjured bone. Pharmacologically, the Adrb2 antagonist propranolol impairs, and the agonist formoterol promotes fracture healing in aged mice by regulating callus neovascularization. Clinically, intravenous beta-adrenergic sympathomimetics are associated with improved callus formation in trauma patients with long bone fractures. Thus, Adrb2 is a novel target for promoting bone healing, and widely used beta-blockers may cause fracture nonunion under conditions of increased sympathetic tone.

Abstract Figure

Adipose Tissue Remodeling in Obesity: An Overview of the Actions of Thyroid Hormones and Their Derivatives

Metabolic syndrome and obesity have become important health issues of epidemic proportions and are often the cause of related pathologies such as type 2 diabetes (T2DM), hypertension, and cardiovascular disease. Adipose tissues (ATs) are dynamic tissues that play crucial physiological roles in maintaining health and homeostasis. An ample body of evidence indicates that in some pathophysiological conditions, the aberrant remodeling of adipose tissue may provoke dysregulation in the production of various adipocytokines and metabolites, thus leading to disorders in metabolic organs. Thyroid hormones (THs) and some of their derivatives, such as 3,5-diiodo-l-thyronine (T2), exert numerous functions in a variety of tissues, including adipose tissues. It is known that they can improve serum lipid profiles and reduce fat accumulation. The thyroid hormone acts on the brown and/or white adipose tissues to induce uncoupled respiration through the induction of the uncoupling protein 1 (UCP1) to generate heat. Multitudinous investigations suggest that 3,3',5-triiodothyronine (T3) induces the recruitment of brown adipocytes in white adipose depots, causing the activation of a process known as "browning". Moreover, in vivo studies on adipose tissues show that T2, in addition to activating brown adipose tissue (BAT) thermogenesis, may further promote the browning of white adipose tissue (WAT), and affect adipocyte morphology, tissue vascularization, and the adipose inflammatory state in rats receiving a high-fat diet (HFD). In this review, we summarize the mechanism by which THs and thyroid hormone derivatives mediate adipose tissue activity and remodeling, thus providing noteworthy perspectives on their efficacy as therapeutic agents to counteract such morbidities as obesity, hypercholesterolemia, hypertriglyceridemia, and insulin resistance.

β-Adrenoreceptors as Therapeutic Targets for Ocular Tumors and Other Eye Diseases-Historical Aspects and Nowadays Understanding

β-adrenoreceptors (ARs) are members of the superfamily of G-protein-coupled receptors (GPCRs), and are activated by catecholamines, such as epinephrine and norepinephrine. Three subtypes of β-ARs (β₁, β₂, and β₃) have been identified with different distributions among ocular tissues. Importantly, β-ARs are an established target in the treatment of glaucoma. Moreover, β-adrenergic signaling has been associated with the development and progression of various tumor types. Hence, β-ARs are a potential therapeutic target for ocular neoplasms, such as ocular hemangioma and uveal melanoma. This review aims to discuss the expression and function of individual β-AR subtypes in ocular structures, as well as their role in the treatment of ocular diseases, including ocular tumors.

Molecular Mechanisms of Carcinogenesis in Pediatric Airways Tumors

Primary tumors of the airways in the pediatric population are very rare entities. For this reason, little is known about the pathogenesis of these neoplasms. Understanding the biology has different practical implications: for example, it could help in the differential diagnosis, have a prognostic significance, or may lead to the development of a targeted therapy. The aim of this article is to present the current knowledge about pediatric airways tumors, focusing on the molecular mechanisms that cause the onset and progression of these neoplasms. After a brief introduction of epidemiology and clinical presentation, the tumorigenesis of the most frequent pediatric airways tumors will be described: Juvenile-onset recurrent respiratory papillomatosis (JORRP), Subglottic Hemangiona (SH), Rhabdomyosarcoma (RMS), and Mucoepidermoid carcinoma (MEC).

Adrenoceptors and SCD1 in adipocytes/adipose tissues: The expression and variation in health and obesity

Obesity, considered a metabolic disorder, is one of the most significant health issues that the community has to cope with today. A rising number of studies have been conducted to find out promising genetic targets for obese treatment. The sympathetic nervous system was proven to possess remarkable roles in energy metabolism, including the stimulation of lipolysis as well as thermogenesis, via distinct adrenoceptors appearing on the membrane of adipocyte. A decrease of β-adrenoceptor expression has been observed in obese individuals, which is related to reducing energy expenditure and developing obesity. While that the deficiency of stearoyl-CoA desaturase-1 (SCD1), which is a promising target for treatments of metabolic diseases, decreases oxidation and promotes the synthesis of fatty acids. Here, we emphasized several differences between distinct adrenoceptor subtypes, including their mRNA expression level and function in white adipose tissue and brown adipose tissue. We also highlighted SCD1's roles related to the progression of adipocytes and its changing expression under the obese condition in both rodents and humans, and furthermore, tried to figure out the interaction between adrenoceptors and SCD1 in adipose tissue.

Hypoxia as a Double-Edged Sword to Combat Obesity and Comorbidities

The global epidemic of obesity is tightly associated with numerous comorbidities, such as type II diabetes, cardiovascular diseases and the metabolic syndrome. Among the key features of obesity, some studies have suggested the abnormal expansion of adipose-tissue-induced local endogenous hypoxic, while other studies indicated endogenous hyperoxia as the opposite trend. Endogenous hypoxic aggravates dysfunction in adipose tissue and stimulates secretion of inflammatory molecules, which contribute to obesity. In contrast, hypoxic exposure combined with training effectively generate exogenous hypoxic to reduce body weight and downregulate metabolic risks. The (patho)physiological effects in adipose tissue are distinct from those of endogenous hypoxic. We critically assess the latest advances on the molecular mediators of endogenous hypoxic that regulate the dysfunction in adipose tissue. Subsequently we propose potential therapeutic targets in adipose tissues and the small molecules that may reverse the detrimental effect of local endogenous hypoxic. More importantly, we discuss alterations of metabolic pathways in adipose tissue and the metabolic benefits brought by hypoxic exercise. In terms of therapeutic intervention, numerous approaches have been developed to treat obesity, nevertheless durability and safety remain the major concern. Thus, a combination of the therapies that suppress endogenous hypoxic with exercise plans that augment exogenous hypoxic may accelerate the development of more effective and durable medications to treat obesity and comorbidities.

Association between vascular endothelial growth factor-mediated blood-brain barrier dysfunction and stress-induced depression

Several lines of evidence suggest that stress induces the neurovascular dysfunction associated with increased blood-brain barrier (BBB) permeability, which could be an important pathology linking stress and psychiatric disorders, including major depressive disorder (MDD). However, the detailed mechanism resulting in BBB dysfunction associated in the pathophysiology of MDD still remains unclear. Herein, we demonstrate the role of vascular endothelial growth factor (VEGF), a key mediator of vascular angiogenesis and BBB permeability, in stress-induced BBB dysfunction and depressive-like behavior development. We implemented an animal model of depression, chronic restraint stress (RS) in BALB/c mice, and found that the BBB permeability was significantly increased in chronically stressed mice. Immunohistochemical and electron microscopic observations revealed that increased BBB permeability was associated with both paracellular and transcellular barrier alterations in the brain endothelial cells. Pharmacological inhibition of VEGF receptor 2 (VEGFR2) using a specific monoclonal antibody (DC101) prevented chronic RS-induced BBB permeability and anhedonic behavior. Considered together, these results indicate that VEGF/VEGFR2 plays a crucial role in the pathogenesis of depression by increasing the BBB permeability, and suggest that VEGFR2 inhibition could be a potential therapeutic strategy for the MDD subtype associated with BBB dysfunction.

Activation of cAMP Signaling in Response to α-Phellandrene Promotes Vascular Endothelial Growth Factor Levels and Proliferation in Human Dermal Papilla Cells

Dermal papilla cells (DPCs) are growth factor reservoirs that are specialized for hair morphogenesis and regeneration. Due to their essential role in hair growth, DPCs are commonly used as an in vitro model to investigate the effects of hair growth-regulating compounds and their molecular mechanisms of action. Cyclic adenosine monophosphate (cAMP), an intracellular second messenger, is currently employed as a growth-promoting target molecule. In a pilot test, we found that α-phellandrene, a naturally occurring phytochemical, increased cAMP levels in DPCs. Therefore, we sought to determine whether α-phellandrene increases growth factors and proliferation in human DPCs and to identify the underlying mechanisms. We demonstrated that α-phellandrene promotes cell proliferation concentration-dependently. In addition, it increases the cAMP downstream effectors, such as protein kinase A catalytic subunit (PKA Cα) and phosphorylated cAMP-responsive element-binding protein (CREB). Also, among the CREB-dependent growth factor candidates, we identified that α-phellandrene selectively upregulated vascular endothelial growth factor (VEGF) mRNA expression in DPCs. Notably, the beneficial effects of α-phellandrene were nullified by a cAMP inhibitor. This study demonstrated the cAMP-mediated growth effects in DPCs and the therapeutic potential of α-phellandrene for preventing hair loss.

Depot- and diabetes-specific differences in norepinephrine-mediated adipose tissue angiogenesis, vascular tone, collagen deposition and morphology in obesity

AIMS

Norepinephrine (NE) is a known regulator of adipose tissue (AT) metabolism, angiogenesis, vasoconstriction and fibrosis. This may be through autocrine/paracrine effects on local resistance vessel function and morphology. The aims of this study were to investigate, in human subcutaneous and omental adipose tissue (SAT and OAT): NE synthesis, angiogenesis, NE-mediated arteriolar vasoconstriction, the induction of collagen gene expression and its deposition in non-diabetic versus diabetic obese subjects.

MATERIALS AND METHODS

SAT and OAT from obese patients were used to investigate tissue NE content, tyrosine hydroxylase (TH) density, angiogenesis including capillary density, angiogenic capacity and angiogenic gene expression, NE-mediated arteriolar vasoconstriction and collagen deposition.

KEY FINDINGS

In the non-diabetic group, NE concentration, TH immunoreactivity, angiogenesis and maximal vasoconstriction were significantly higher in OAT compared to SAT (p < 0.05). However, arterioles from OAT showed lower NE sensitivity compared to SAT (10^-8 M to 10^-7.5 M, p < 0.05). A depot-specific difference in collagen deposition was also observed, being greater in OAT than SAT. In the diabetic group, no significant depot-specific differences were seen in NE synthesis, angiogenesis, vasoconstriction or collagen deposition. SAT arterioles showed significantly lower sensitivity to NE (10^-8 M to 10^-7.5 M, p < 0.05) compared to the non-diabetic group.

SIGNIFICANCE

SAT depot in non-diabetic obese patients exhibited relatively low NE synthesis, angiogenesis, tissue fibrosis and high vasoreactivity, due to preserved NE sensitivity. The local NE synthesis in OAT and diabetes desensitizes NE-induced vasoconstriction, and may also explain the greater tissue angiogenesis and fibrosis in these depots.

Skeletal muscle provides a pro-browning microenvironment for transplanted brown adipose tissue to maintain its effect to ameliorate obesity in ob/ob mice

Brown adipose tissue (BAT) transplantation is a promising means of increasing whole-body energy metabolism to ameliorate obesity. However, the changes in BAT following transplantation and the effects of the microenvironment of the recipient site on graft function have yet to be fully characterized. Therefore, we aimed to determine the effects of transplanting BAT from C57BL/6 mice into the dorsal subcutaneous region or deep to the quadriceps femoris muscle of leptin-deficient ob/ob mice. Subcutaneously transplanted BAT lost features of BAT and demonstrated greater inflammatory cell infiltration and more oil cysts 16 weeks following transplantation. By contrast, the sub-muscularly transplanted BAT maintained features of BAT and was more highly vascularized. Interestingly, sub-muscular BAT transplantation led to a significant increase in oxygen consumption and less inflammation in subcutaneous fat, which was associated with long-term reductions in insulin resistance and body mass gain, whereas the subcutaneous transplants failed after 16 weeks. These results demonstrate that the beneficial effects of BAT transplantation depend upon the microenvironment of the recipient site. Skeletal muscle may provide a microenvironment that maintains the inherent features of BAT grafts over a long period of time, which facilitates a reduction in obesity and improvements in glucose homeostasis.

Mitophagy receptor FUNDC1 is regulated by PGC-1α/NRF1 to fine tune mitochondrial homeostasis

Mitophagy is an essential cellular autophagic process that selectively removes superfluous and damaged mitochondria, and it is coordinated with mitochondrial biogenesis to fine tune the quantity and quality of mitochondria. Coordination between these two opposing processes to maintain the functional mitochondrial network is of paramount importance for normal cellular and organismal metabolism. However, the underlying mechanism is not completely understood. Here we report that PGC-1α and nuclear respiratory factor 1 (NRF1), master regulators of mitochondrial biogenesis and metabolic adaptation, also transcriptionally upregulate the gene encoding FUNDC1, a previously characterized mitophagy receptor, in response to cold stress in brown fat tissue. NRF1 binds to the classic consensus site in the promoter of Fundc1 to upregulate its expression and to enhance mitophagy through its interaction with LC3. Specific knockout of Fundc1 in BAT results in reduced mitochondrial turnover and accumulation of functionally compromised mitochondria, leading to impaired adaptive thermogenesis. Our results demonstrate that FUNDC1-dependent mitophagy is directly coupled with mitochondrial biogenesis through the PGC-1α/NRF1 pathway, which dictates mitochondrial quantity, quality, and turnover and contributes to adaptive thermogenesis.

Triiodothyronine stimulates steroid and VEGF production in murine Leydig cells via cAMP-PKA pathway

Thyroid hormones affect testicular development as well as functions like spermatogenesis and steroidogenesis, thereby influencing male fertility. Our group earlier showed that the stimulatory role of the thyroid hormone, T₃ , on the production of vascular endothelial growth factor (VEGF) by murine Leydig cells is mediated by steroids and hypoxia-inducible factor-1 (HIF-1α). The current study further defines the signalling pathway(s) utilised by T₃ to stimulate the production of steroids, VEGF and HIF-1α in mouse Leydig tumour cell line (MLTC-1). Specific inhibitors for different signalling molecules were used to study the role of cyclic AMP (cAMP), and its downstream mediators. Expression of VEGF and HIF-1α mRNA were measured by quantitative RT-PCR; VEGF secretion by ELISA; steroid secretion by radioimmunoassay and HIF-1α protein levels by western blotting. Inhibitors of adenylate cyclase (AC), protein kinase A (PKA), sarcoma kinase (SrcK), phosphoinositide 3-kinase (PI3K) and MAP kinase kinase (MEK1/2) abolished the T₃ -induced increase in VEGF mRNA and protein levels. The same signalling molecules also mediated the increased production of steroids and HIF-1α protein in response to T₃ . Therefore, it was concluded that T₃ stimulates steroid secretion and HIF-1α protein in MLTC-1 cells through the AC-cAMP-PKA-PI3K-MEK pathway, which in turn stimulate VEGF production.

Oral atenolol treatment for infantile hemangiomas: clinical analysis of 133 consecutive patients

Background

Infantile hemangiomas (IHs) are the most frequently occurring pediatric lesions. Oral propranolol has been shown to be safe and effective in infants with IHs. Side effects such as sleep disturbances have been associated with propranolol. Atenolol is a hydrophilic, selective β1-blocker and therefore may be not associated with side effects attributable to β2-adrenergic receptor blockade and lipophilicity. However, the efficacy of atenolol in the treatment of IHs is poorly understood. The aim of this study was to evaluate the efficacy of atenolol in the treatment of proliferating IHs in a clinical cohort including 133 consecutive patients.

Methods

In this study, we enrolled 133 patients diagnosed as proliferating IHs from the routine clinical and referral practices of the authors. The procedures followed were in accordance with the ethical standards of the Institute Review Board of Shanghai Ninth People's Hospital and Helsinki Declaration. Clinical characteristics, including demographic data and clinical morphology, were collated. Responses to oral atenolol therapy were graded as: excellent, good, fair and poor. According to the reaction to atenolol treatment, additional medications or therapy were used for IH patients to achieve satisfactory clinical results.

Results

In this study, 128 (96.2%) of 133 IH patients responded to oral atenolol, and the response rate (RR) was significantly different for different ages of patients (P<0.05), with the youngest patients having the highest RR. The mean time of treatment was 4.9 months. Forty-one patients who exhibited residual hyperpigmentation or telangiectasia were further treated with timolol maleate cream (n=32) or pulsed dye laser (n=9). All the 41 patients showed positive response. No life-threatening complications were noted during and after oral atenolol. Only 4 (3.0%) of 133 patients developed minor complications including diarrhea. No agitation and bronchospasm were noted in our study.

Conclusions

This study demonstrated that atenolol was effective in the treatment of IHs. Compared to propranolol, atenolol seems to have a similar effect on IHs. Furthermore, atenolol seems to be less frequently associated with potentially life-threatening side effects.

RNAi-mediated knock-down of the dopamine beta-hydroxylase gene changes growth of razor clams

Dopamine beta-hydroxylase (DβH) plays an essential role in the synthesis of catecholamines (CA) in neuroendocrine networks. In the razor clam, Sinonovacula constricta a novel gene for DβH (ScDβH-α) was identified that belongs to the copper type II ascorbate-dependent monooxygenase family. Expression analysis revealed ScDβH-α gene transcripts were abundant in the liver and expressed throughout development. Knock-down of ScDβH-α in adult clams using siRNA caused a reduction in the growth rate compared to control clams. Reduced growth was associated with strong down-regulation of gene transcripts for the growth-related factors, platelet derived growth factors A (PDGF-A) (P < 0.001) 24 h after ScDβH-α knock-down, vascular endothelial growth factor (VEGF1) (P < 0.001) and platelet derived growth factor B (PDGF-B-2) (P < 0.001) 24 h and 48 h after ScDβH-α knock-down and transforming growth factor beta (TGF-β1) (P < 0.001) 48 h and 72 h after ScDβH-α knock-down. Taken together the results suggest that the novel ScDβH-α gene through its role in CA synthesis is involved in growth regulation in the razor clam and possibly other bivalves.

Spontaneous and Induced Animal Models for Cancer Research

Considering the complexity of the current framework in oncology, the relevance of animal models in biomedical research is critical in light of the capacity to produce valuable data with clinical translation. The laboratory mouse is the most common animal model used in cancer research due to its high adaptation to different environments, genetic variability, and physiological similarities with humans. Beginning with spontaneous mutations arising in mice colonies that allow for pursuing studies of specific pathological conditions, this area of in vivo research has significantly evolved, now capable of generating humanized mice models encompassing the human immune system in biological correlation with human tumor xenografts. Moreover, the era of genetic engineering, especially of the hijacking CRISPR/Cas9 technique, offers powerful tools in designing and developing various mouse strains. Within this article, we will cover the principal mouse models used in oncology research, beginning with behavioral science of animals vs. humans, and continuing on with genetically engineered mice, microsurgical-induced cancer models, and avatar mouse models for personalized cancer therapy. Moreover, the area of spontaneous large animal models for cancer research will be briefly presented.

SYSTEMIC BETA-BLOCKERS AND RISK OF PROGRESSION TO NEOVASCULAR AGE-RELATED MACULAR DEGENERATION

PURPOSE

To determine whether oral beta-blockers (BBs) are associated with the development of neovascular age-related macular degeneration (nAMD).

METHODS

Retrospective cohort study of patients from 2000 to 2014 using data from a large national U.S. insurer's administrative medical claims database. Patients with nonexudative AMD who initiated (index date) BB, a calcium channel blocker (CCB), an angiotensin-converting enzyme/angiotensin receptor blocker, or a diuretic. Patients were excluded for <2 years in the plan before the index date, any history of nAMD or diagnosis, or treatment for an ocular disease that could be confused with nAMD. Hazard of developing of nAMD was the main outcome measure. Primary analysis compared BB with CCB patients with BB versus the other classes as secondary analyses. In addition, a sensitivity analysis was performed between BB and CCB cohorts using 1:1 propensity score matching. Cox proportional hazard regression was performed to estimate the hazard ratio (HR) of developing nAMD at 90, 180, and 365 days for BB. Covariates of interest included demographic information, year of index date, number of antihypertensive medications, and other comorbid systemic conditions.

RESULTS

Eighteen thousand seven hundred and fifty-four BB patients and 12,784 CCB patients met criteria for inclusion. After controlling for covariates, patients on BB had a lower hazard for nAMD at both 90 and 180 days than patients on CCB (HRs: 0.67-0.71; P < 0.01 for both) and diuretics (HRs: 0.55-0.62; P < 0.01). Patients on BB versus angiotensin-converting enzyme/angiotensin receptor blocker at all time points and BB versus CCB and diuretics at 365 days did not have a significantly lower association with nAMD (HR: 0.73-0.85; P > 0.06 for all comparisons). A sensitivity analysis using propensity score matching yielded similar results with patients on BB significantly less likely to develop nAMD at 90 and 180 days (HR: 0.70-0.76; P < 0.049 for both) but not at 365 days (HR: 0.88; P = 0.30) compared with patients on CCB.

CONCLUSION

No evidence was found that BB usage increased the hazard for nAMD relative to other antihypertensive medications.

Liver regeneration and liver metastasis

Surgical resection for primary and secondary hepatic neoplasms provides the best chance of cure. Advanced surgical techniques such as portal vein embolisation, two-staged hepatectomy and associated liver partition and portal vein ligation for staged-hepatectomy (ALPPS) have facilitated hepatic resection in patients with previously unresectable, bi-lobar disease. These techniques are frequently employed to ensure favourable clinical outcomes and avoid potentially fatal post-operative complications such as small for size syndrome and post-hepatectomy liver failure. However, they rely on the innate ability of the liver to regenerate. As our knowledge of liver organogenesis, liver regeneration and hepatocarcinogenesis has expanded in recent decades it has come to light that liver regeneration may also drive tumour recurrence. Clinical studies in patients undergoing portal vein embolisation indicate that tumours may progress following the procedure in concordance with liver regeneration and hypertrophy, however overall survival in these patients has not been shown to be worse. In this article, we delve into the mechanisms underlying liver regeneration to better understand the complex ways in which this may affect tumour behaviour and ultimately inform clinical decisions.

Brown Fat Promotes Muscle Growth During Regeneration

Accumulation of adipose tissue around and within muscles is highly correlated with reduced strength, functional limitations, and poor rehabilitative outcomes. Given the intimate physical contact between these tissues, paracrine cross-talk is a likely mediator of this association. The recent discovery that muscle-associated adipose tissue exhibits features of beige fat has suggested that this cross-talk may be modifiable, as beige fat can be stimulated to assume features of brown fat. In this work, we describe a novel intermuscular fat transplant model in the mouse rotator cuff to investigate cross-talk between muscle and adipose tissue. Specifically, we examine the role of transplanted fat phenotype on muscle regeneration by transplanting pieces of classical brown (interscapular), beige (inguinal), or white (epididymal) adipose tissue in conjunction with cardiotoxin injection to the adjacent supraspinatus muscle. Transplantation of brown fat, but not beige or white, significantly increased muscle mass, fiber cross-sectional area and contractile force production compared with sham injury. This effect was not seen when cardiotoxin was delivered to a distant muscle, or when adjacent muscles were injected with saline indicating that the effect is localized and specifically targeting the regenerative process. Thus, we conclude that local signaling between fat and muscle varies by phenotype and that brown fat supports regeneration. Clinical significance: Our findings suggest that the phenotype of muscle-associated fat could be a novel therapeutic target to modulate fat-muscle signaling. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1817-1826, 2019.

Adrenoceptors in white, brown, and brite adipocytes

Adrenoceptors play an important role in adipose tissue biology and physiology that includes regulating the synthesis and storage of triglycerides (lipogenesis), the breakdown of stored triglycerides (lipolysis), thermogenesis (heat production), glucose metabolism, and the secretion of adipocyte-derived hormones that can control whole-body energy homeostasis. These processes are regulated by the sympathetic nervous system through actions at different adrenoceptor subtypes expressed in adipose tissue depots. In this review, we have highlighted the role of adrenoceptor subtypes in white, brown, and brite adipocytes in both rodents and humans and have included detailed analysis of adrenoceptor expression in human adipose tissue and clonally derived adipocytes. We discuss important considerations when investigating adrenoceptor function in adipose tissue or adipocytes. LINKED ARTICLES: This article is part of a themed section on Adrenoceptors-New Roles for Old Players. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.14/issuetoc.

Molecular pathways linking adipose innervation to insulin action in obesity and diabetes mellitus

Adipose tissue comprises adipocytes and many other cell types that engage in dynamic crosstalk in a highly innervated and vascularized tissue matrix. Although adipose tissue has been studied for decades, it has been appreciated only in the past 5 years that extensive arborization of nerve fibres has a dominant role in regulating the function of adipose tissue. This Review summarizes the latest literature, which suggests that adipocytes signal to local sensory nerve fibres in response to perturbations in lipolysis and lipogenesis. Such adipocyte signalling to the central nervous system causes sympathetic output to distant adipose depots and potentially other metabolic tissues to regulate systemic glucose homeostasis. Paracrine factors identified in the past few years that mediate such adipocyte-neuron crosstalk are also reviewed. Similarly, immune cells and endothelial cells within adipose tissue communicate with local nerve fibres to modulate neurotransmitter tone, blood flow, adipocyte differentiation and energy expenditure, including adipose browning to produce heat. This understudied field of neurometabolism related to adipose tissue biology has great potential to reveal new mechanistic insights and potential therapeutic strategies for obesity and type 2 diabetes mellitus.

Norepinephrine triggers an immediate-early regulatory network response in primary human white adipocytes

BACKGROUND

Norepinephrine (NE) signaling has a key role in white adipose tissue (WAT) functions, including lipolysis, free fatty acid liberation and, under certain conditions, conversion of white into brite (brown-in-white) adipocytes. However, acute effects of NE stimulation have not been described at the transcriptional network level.

RESULTS

We used RNA-seq to uncover a broad transcriptional response. The inference of protein-protein and protein-DNA interaction networks allowed us to identify a set of immediate-early genes (IEGs) with high betweenness, validating our approach and suggesting a hierarchical control of transcriptional regulation. In addition, we identified a transcriptional regulatory network with IEGs as master regulators, including HSF1 and NFIL3 as novel NE-induced IEG candidates. Moreover, a functional enrichment analysis and gene clustering into functional modules suggest a crosstalk between metabolic, signaling, and immune responses.

CONCLUSIONS

Altogether, our network biology approach explores for the first time the immediate-early systems level response of human adipocytes to acute sympathetic activation, thereby providing a first network basis of early cell fate programs and crosstalks between metabolic and transcriptional networks required for proper WAT function.

Beyond endothelial cells: Vascular endothelial growth factors in heart, vascular anomalies and placenta

Vascular endothelial growth factors regulate vascular and lymphatic growth. Dysregulation of VEGF signaling is connected to many pathological states, including hemangiomas, arteriovenous malformations and placental abnormalities. In heart, VEGF gene transfer induces myocardial angiogenesis. Besides vascular and lymphatic endothelial cells, VEGFs affect multiple other cell types. Understanding VEGF biology and its paracrine signaling properties will offer new targets for novel treatments of several diseases.

HDAC6 regulates thermogenesis of brown adipocytes through activating PKA to induce UCP1 expression

Mitochondrial uncoupling protein 1 (UCP1) is responsible for nonshivering thermogenesis in brown adipose tissue (BAT). UCP1 increases the conductance of the inner mitochondrial membrane (IMM) for protons to make BAT mitochondria generate heat rather than ATP. HDAC6 is a cytosolic deacetylase for non-histone substrates to regulate various cellular processes, including mitochondrial quality control and dynamics. Here, we showed that the body temperature of HDAC6 knockout mice is slightly decreased in normal hosing condition. Interestingly, UCP1 was downregulated in BAT of HDAC6 knockout mice, which extensively linked mitochondrial thermogenesis. Mechanistically, we showed that cAMP-PKA signaling plays a key role in HDAC6-dependent UCP1 expression. Notably, the size of brown adipocytes and lipid droplets in HDAC6 knockout BAT is increased. Taken together, our findings suggested that HDAC6 contributes to mitochondrial thermogenesis in BAT by increasing UCP1 expression through cAMP-PKA signaling pathway.

Cell proliferation and apoptosis inhibition: essential processes for recruitment of the full thermogenic capacity of brown adipose tissue

In mice living under normal animal house conditions, the brown adipocytes in classical brown adipose tissue depots are already essentially fully differentiated: UCP1 mRNA and UCP1 protein levels are practically saturated. This means that any further recruitment - in response to cold exposure or any other browning agent - does not result in significant augmentation of these parameters. This may easily be construed to indicate that classical brown adipose tissue cannot be further recruited. However, this is far from the case: the capacity for further recruitment instead lies in the ability of the tissue to increase the number of brown-fat cells, a remarkable and highly controlled physiological recruitment process. We have compiled here the available data concerning the unique ability of norepinephrine to increase cell proliferation and inhibit apoptosis in brown adipocytes. Adrenergically stimulated cell proliferation is fully mediated via β₁-adrenoceptors and occurs through activation of stem cells in the tissue; intracellular mediation of the signal involves cAMP and protein kinase A activation, but activation of Erk1/2 is not part of the pathway. Apoptosis inhibition in brown adipocytes is induced by both β- and α₁-adrenergic receptors and here the intracellular pathway includes Erk1/2 activation. This unique ability of norepinephrine to increase cell number in an apparently mitogenically dormant tissue provides possibilities to augment the metabolic capacity of brown adipose tissue, also for therapeutic purposes.

Three-dimensional volume fluorescence-imaging of vascular plasticity in adipose tissues

Objective

The vascular system is central to sustaining tissue survival and homeostasis. Blood vessels are densely present in adipose tissues and exert essential roles in their metabolism. However, conventional immunohistochemistry methods have intrinsic limitations in examining the 3D vascular network in adipose tissues as well as other organs in general.

Methods

We established a 3D volume fluorescence-imaging technique to visualize the vasculatures in mouse adipose tissues by combining the optimized steps of whole-mount immunolabeling, tissue optical clearing, and lightsheet volume fluorescence-imaging. To demonstrate the strength of this novel imaging procedure, we comprehensively assessed the intra-adipose vasculatures under obese conditions or in response to a cold challenge.

Results

We show the entirety of the vascular network in mouse adipose tissues on the whole-tissue level at a single-capillary resolution for the first time in the field. We accurately quantify the pathological changes of vasculatures in adipose tissues in wild-type or obese mice (ob/ob, db/db, or diet-induced obesity). In addition, we identify significant and reversible changes of the intra-adipose vasculatures in the mice subjected to cold challenge (i.e., 4°). Furthermore, we demonstrate that the cold-induced vascular plasticity depends on the sympathetic-derived catecholamine signal and is involved in the beiging process of white adipose tissues.

Conclusions

We report a 3D volume fluorescence-imaging procedure that is compatible with many areas of vascular research and is poised to serve the field in future investigations of the vascular system in adipose tissues or other research scenarios.

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3D vascular network in adipose tissues is visualized at single-capillary resolution.

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Pathological remodeling of vasculatures is characterized under the obese conditions.

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Vascular plasticity during cold challenge is involved in the beiging process of WAT.

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Sympathetic-derived catecholamine signal regulates the vascular plasticity in WAT.

Effect of Iodothyronines on Thermogenesis: Focus on Brown Adipose Tissue

Thyroid hormones significantly influence energy expenditure by affecting the activity of metabolic active tissues, among which, mammalian brown adipose tissue (BAT) plays a significant role. For a long time, the modulation of BAT activity by 3,3',5-triiodo-l-thyronine (T3) has been ascribed to its direct actions on this tissue; however, recent evidence indicates that T3, by stimulating specific brain centers, activates the metabolism of BAT via the sympathetic nervous system. These distinct mechanisms of action are not mutually exclusive. New evidence indicates that 3,5-diiodo-l-thyronine (3,5-T2), a thyroid hormone derivative, exerts thermogenic effects, by influencing mitochondrial activity in metabolically active tissues, such as liver, skeletal muscle, and BAT. At the moment, due to the absence of experiments finalized to render a clear cut discrimination between peripheral and central effects induced by 3,5-T2, it is not possible to exclude that some of the metabolic effects exerted by 3,5-T2 may be mediated centrally. Despite this, some evidence suggests that 3,5-T2 plays a role in adrenergic stimulation of thermogenesis in BAT. This mini-review provides an overview of the effects induced by T3 and 3,5-T2 on BAT thermogenesis, with a focus on data suggesting the involvement of central adrenergic stimulation. These aspects may reveal new perspectives in thyroid physiology and in the control of energy metabolism.

Biventricular differences in β-adrenergic receptor signaling following burn injury

Burn injury detrimentally affects the myocardium, primarily due to over-activation of β-adrenergic receptors (β-AR). Autopsy reports from our institution reveal that patients often suffer from right ventricle (RV) failure. Since burn injury affects β-AR signaling in the left ventricle (LV), we proposed that β-AR signaling may also be altered in the RV. A rodent model with a scald burn of 60% of the total body surface area was used to test this hypothesis. Ventricles were isolated 7 days post-burn. We examined the expression of β-ARs via Western blotting and the mRNA expression of downstream signaling proteins via qRT-PCR. Cyclic adenosine monophosphate (cAMP) production and protein kinase A (PKA) activity were measured in membrane and cytosolic fractions, respectively, using enzyme immunoassay kits. β₁-AR protein expression was significantly increased in the RV following burn injury compared to non-burned RV but not in the LV (p = 0.0022). In contrast, β₂-AR expression was unaltered among the groups while G_αi expression was significantly higher in the LV post-burn (p = 0.023). B-arrestin-1 and G-protein coupled receptor kinase-2 mRNA expression were significantly increased in the left ventricle post-burn (p = 0.001, p<0.0001, respectively). cAMP production and PKA activity were significantly lower in the LV post-burn (p = 0.0063, 0.0042, respectively). These data indicate that burn injury affects the β-AR signaling pathway in the RV independently of the LV. Additionally, non-canonical β-AR signaling may be activated in the RV as cAMP production and PKA activity were unchanged despite changes in β₁-AR protein expression.

Increased inflammation, oxidative stress and mitochondrial respiration in brown adipose tissue from obese mice

Obesity is associated with severe metabolic diseases such as type 2 diabetes, insulin resistance, cardiovascular disease and some forms of cancer. The pathophysiology of obesity-induced metabolic diseases has been strongly related to white adipose tissue (WAT) dysfunction through several mechanisms such as fibrosis, apoptosis, inflammation, ER and oxidative stress. However, little is known of whether these processes are also present in brown adipose tissue (BAT) during obesity, and the potential consequences on mitochondrial activity. Here we characterized the BAT of obese and hyperglycemic mice treated with a high-fat diet (HFD) for 20 weeks. The hypertrophic BAT from obese mice showed no signs of fibrosis nor apoptosis, but higher levels of inflammation, ER stress, ROS generation and antioxidant enzyme activity than the lean counterparts. The response was attenuated compared with obesity-induced WAT derangements, which suggests that BAT is more resistant to the obesity-induced insult. In fact, mitochondrial respiration in BAT from obese mice was enhanced, with a 2-fold increase in basal oxygen consumption, through the upregulation of complex III of the electron transport chain and UCP1. Altogether, our results show that obesity is accompanied by an increase in BAT mitochondrial activity, inflammation and oxidative damage.

Cell biology of fat storage

The worldwide epidemic of obesity and type 2 diabetes has greatly increased interest in the biology and physiology of adipose tissues. Adipose (fat) cells are specialized for the storage of energy in the form of triglycerides, but research in the last few decades has shown that fat cells also play a critical role in sensing and responding to changes in systemic energy balance. White fat cells secrete important hormone-like molecules such as leptin, adiponectin, and adipsin to influence processes such as food intake, insulin sensitivity, and insulin secretion. Brown fat, on the other hand, dissipates chemical energy in the form of heat, thereby defending against hypothermia, obesity, and diabetes. It is now appreciated that there are two distinct types of thermogenic fat cells, termed brown and beige adipocytes. In addition to these distinct properties of fat cells, adipocytes exist within adipose tissue, where they are in dynamic communication with immune cells and closely influenced by innervation and blood supply. This review is intended to serve as an introduction to adipose cell biology and to familiarize the reader with how these cell types play a role in metabolic disease and, perhaps, as targets for therapeutic development.

Harnessing cAMP signaling in musculoskeletal regenerative engineering

This paper reviews the most recent findings in the search for small molecule cyclic AMP analogues regarding their potential use in musculoskeletal regenerative engineering.

Gene expression profiles and signaling mechanisms in α2B-adrenoceptor-evoked proliferation of vascular smooth muscle cells

BACKGROUND

α2-adrenoceptors are important regulators of vascular tone and blood pressure. Regulation of cell proliferation is a less well investigated consequence of α2-adrenoceptor activation. We have previously shown that α2B-adrenoceptor activation stimulates proliferation of vascular smooth muscle cells (VSMCs). This may be important for blood vessel development and plasticity and for the pathology and therapeutics of cardiovascular disorders. The underlying cellular mechanisms have remained mostly unknown. This study explored pathways of regulation of gene expression and intracellular signaling related to α2B-adrenoceptor-evoked VSMC proliferation.

RESULTS

The cellular mechanisms and signaling pathways of α2B-adrenoceptor-evoked proliferation of VSMCs are complex and include redundancy. Functional enrichment analysis and pathway analysis identified differentially expressed genes associated with α2B-adrenoceptor-regulated VSMC proliferation. They included the upregulated genes Egr1, F3, Ptgs2 and Serpine1 and the downregulated genes Cx3cl1, Cav1, Rhoa, Nppb and Prrx1. The most highly upregulated gene, Lypd8, represents a novel finding in the VSMC context. Inhibitor library screening and kinase activity profiling were applied to identify kinases in the involved signaling pathways. Putative upstream kinases identified by two different screens included PKC, Raf-1, Src, the MAP kinases p38 and JNK and the receptor tyrosine kinases EGFR and HGF/HGFR. As a novel finding, the Src family kinase Lyn was also identified as a putative upstream kinase.

CONCLUSIONS

α2B-adrenoceptors may mediate their pro-proliferative effects in VSMCs by promoting the activity of bFGF and PDGF and the growth factor receptors EGFR, HGFR and VEGFR-1/2. The Src family kinase Lyn was also identified as a putative upstream kinase. Lyn is known to be expressed in VSMCs and has been identified as an important regulator of GPCR trafficking and GPCR effects on cell proliferation. Identified Ser/Thr kinases included several PKC isoforms and the β-adrenoceptor kinases 1 and 2. Cross-talk between the signaling mechanisms involved in α2B-adrenoceptor-evoked VSMC proliferation thus appears to involve PKC activation, subsequent changes in gene expression, transactivation of EGFR, and modulation of kinase activities and growth factor-mediated signaling. While many of the identified individual signals were relatively small in terms of effect size, many of them were validated by combining pathway analysis and our integrated screening approach.

G protein, phosphorylated-GATA4 and VEGF expression in the hearts of transgenic mice overexpressing β1- and β2-adrenergic receptors

β₁- and β₂-adrenergic receptors (ARs) regulate cardiac contractility, calcium handling and protein phosphorylation. The present study aimed to examine the expression levels of vascular endothelial growth factor A (VEGF-A) and several G proteins, and the phosphorylation of transcription factor GATA binding protein 4 (GATA4), by western blot analysis, using isolated hearts from 6 month-old transgenic (TG) mice that overexpress β₁AR or β₂AR. Cardiac contractility/relaxation and heart rate was increased in both β₁AR TG and β₂AR TG mouse hearts compared with wild type; however, no significant differences were observed between the β₁- and β₂AR TG mouse hearts. Protein expression levels of inhibitory guanine nucleotide-binding protein (Gi) 2, Gi3 and G-protein-coupled receptor kinase 2 were upregulated in both TG mice, although the upregulation of Gi2 was more prominent in the β₂AR TG mice. VEGF-A expression levels were also increased in both TG mice, and were highest in the β₁AR TG mice. In addition, the levels of phosphorylated-GATA4 expression were increased in β₁- and β₂AR TG mice. In conclusion, the present study demonstrated that cardiac contractility/relaxation and heart rate is increased in β₁AR TG and β₂AR TG mice, and indicated that this increase may be related to the overexpression of G proteins and G-protein-associated proteins.

β3-Adrenergically induced glucose uptake in brown adipose tissue is independent of UCP1 presence or activity: Mediation through the mTOR pathway

Objective

Today, the presence and activity of brown adipose tissue (BAT) in adult humans is generally equated with the induced accumulation of [2-¹⁸F]2-fluoro-2-deoxy-d-glucose ([¹⁸F]FDG) in adipose tissues, as investigated by positron emission tomography (PET) scanning. In reality, PET-FDG is currently the only method available for in vivo quantification of BAT activity in adult humans. The underlying assumption is that the glucose uptake reflects the thermogenic activity of the tissue.

Methods

To examine this basic assumption, we here followed [¹⁸F]FDG uptake by PET and by tissue [³H]-2-deoxy-d-glucose uptake in wildtype and UCP1(−/−) mice, i.e. in mice that do or do not possess the unique thermogenic and calorie-consuming ability of BAT.

Results

Unexpectedly, we found that β₃-adrenergically induced (by CL-316,243) glucose uptake was UCP1-independent. Thus, whereas PET-FDG scans adequately reflect glucose uptake, this acute glucose uptake is not secondary to thermogenesis but is governed by an independent cellular signalling, here demonstrated to be mediated via the previously described KU-0063794-sensitive mTOR pathway.

Conclusions

Thus, PET-FDG scans do not exclusively reveal active BAT deposits but rather any tissue possessing an adrenergically-mediated glucose uptake pathway. In contrast, we found that the marked glucose uptake-ameliorating effect of prolonged β₃-adrenergic treatment was UCP1 dependent. Thus, therapeutically, UCP1 activity is required for any anti-diabetic effect of BAT activation.

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β₃-adrenergically glucose uptake in BAT is UCP1-independent.

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Glucose uptake is not secondary to thermogenesis but is through the mTOR pathway.

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Both glucose uptake and thermogenesis are needed to fully effect glucose homeostasis.

Alpha1B adrenoceptor expression is a marker of reduced survival and increased tumor recurrence in patients with endometrioid ovarian cancer

AIM: To investigate the expression patterns of different adrenoceptor isoforms in ovarian cancer and their association with survival and tumor recurrence.

METHODS: The protein expression levels of α1B, α2C and β2 adrenoceptor were assessed in unselected ovarian cancer using immunohistochemistry on microarrayed archival tissue samples. A database containing clinical and pathology parameters and follow-up was used to investigate the association between adrenoceptor isoform expression with ovarian specific survival and tumor recurrence, using univariate and multivariate statistical analysis.

RESULTS: Expression of α1B showed an association with reduced ovarian specific survival (P = 0.05; CI: 1.00-1.49) and increased tumor recurrence (P = 0.021, CI: 1.04-1.69) in the whole patient group. On sub-analysis the expression of α1B in endometrioid cancers (χ² = 5.867, P = 0.015) was found to predict reduced ovarian specific survival and increased tumor recurrence independently of tumor grade, clinical stage and chemotherapy. An association with clinical outcome was not seen for α2C or β2 AR.

CONCLUSION: Alpha1B adrenoceptor protein was found to predict increased risk of tumor recurrence and reduced mortality in patients with endometrioid type ovarian cancer and should be investigated as a biomarker for identifying patients at increased risk of disease progression. Furthermore, α adrenergic receptor antagonists with α1B selectivity should be investigated as a possible adjuvant therapy for treating patients with endometrioid cancer. Proof of principle could be tested in a retrospective population study.

Loss of CAR promotes migration and proliferation of HaCaT cells, and accelerates wound healing in rats via Src-p38 MAPK pathway

The coxsackie and adenovirus receptor (CAR) is a cell adhesion molecule mostly localized to cell-cell contacts in epithelial and endothelial cells. CAR is known to regulate tumor progression, however, its physiological role in keratinocyte migration and proliferation, two essential steps in re-epithelialization during wound healing, has less been investigated. Here we showed that CAR was predominantly expressed in the epidermis of human skin, CAR knockdown by RNAi significantly accelerated HaCaT cell migration and proliferation. In addition, knockdown of CAR in vitro increased p-Src, p-p38, and p-JNK protein levels; however, Src inhibitor PP2 prevented the increase of p-Src and p-p38 induced by CAR RNAi, but not p-JNK, and decelerated cell migration and proliferation. More intriguingly, in vivo CAR RNAi on the skin area surrounding the wounds on rat back visually accelerated wound healing and re-epithelialization process, while treatment with PP2 or p38 inhibitor SB203580 obviously inhibited these effects. By contrast, overexpressing CAR in HaCaT cells significantly decelerated cell migration and proliferation. Above results demonstrate that suppression of CAR could accelerate HaCaT cell migration and proliferation, and promote wound healing in rat skin, probably via Src-p38 MAPK pathway. CAR thus might serve as a novel therapeutic target for facilitating wound healing.

Adipocyte-Specific Hypoxia-Inducible Factor 2α Deficiency Exacerbates Obesity-Induced Brown Adipose Tissue Dysfunction and Metabolic Dysregulation

Angiogenesis is a central regulator for white (WAT) and brown (BAT) adipose tissue adaptation in the course of obesity. Here we show that deletion of hypoxia-inducible factor 2α (HIF2α) in adipocytes (by using Fabp4-Cre transgenic mice) but not in myeloid or endothelial cells negatively impacted WAT angiogenesis and promoted WAT inflammation, WAT dysfunction, hepatosteatosis, and systemic insulin resistance in obesity. Importantly, adipocyte HIF2α regulated vascular endothelial growth factor (VEGF) expression and angiogenesis of obese BAT as well as its thermogenic function. Consistently, obese adipocyte-specific HIF2α-deficient mice displayed BAT dysregulation, associated with reduced levels of uncoupling protein 1 (UCP1) and a dysfunctional thermogenic response to cold exposure. VEGF administration reversed WAT and BAT inflammation and BAT dysfunction in adipocyte HIF2α-deficient mice. Together, our findings show that adipocyte HIF2α is protective against maladaptation to obesity and metabolic dysregulation by promoting angiogenesis in both WAT and BAT and by counteracting obesity-mediated BAT dysfunction.

Shouldn't Propranolol Be Used to Treat All Haemangiomas?

INTRODUCTION

Infantile haemangioma is the most common childhood tumour. These tumours can cause significant functional and cosmetic problems. While there are many treatment modalities, propranolol is increasingly being recognised as the first-line treatment of problematic haemangiomas. This study investigates the use of oral propranolol for the treatment of all haemangiomas at a tertiary children's hospital.

METHOD

This is a retrospective study evaluating 15 children (3 boys and 12 girls) presenting at a tertiary children's hospital with infantile haemangioma during a 24-month period. The protocol consisted of pre-treatment ultrasonic evaluation of the lesion, followed by the commencement of propranolol therapy (2 mg/kg orally in two divided doses), with repeat imaging performed at 16-24 weeks in order to document the dimensional changes. Adverse effects of propranolol were documented. Intralesional bleomycin was utilised as a second-line modality of treatment for large or problematic haemangiomas with inadequate regression in size after oral propranolol therapy.

RESULT

Fifteen (15) patients with a mean age of 7 months (Range: 3-14 months) presented with haemangiomas. Ten patients presented with lesions affecting the head and neck region (67%). Three patients presented with an ulcerated haemangioma, which responded to propranolol and simple dressings and all healed completely. The average decrease in size between the ultrasonography procedures was 48.87%. Only one patient showed no improvement. No side effects were reported. Concomitant bleomycin treatment was reserved for large problematic haemangiomas and proved successful at speeding up the involution process.

CONCLUSION

This study suggests that propranolol become the first-line treatment of choice for all haemangiomas. It has proven to be effective and safe for reducing the size of all haemangiomas during the proliferative phase.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

β-Blockers promote angiogenesis in the mouse aortic ring assay

Recent results indicate that the reduction of β-adrenergic signaling impairs angiogenesis under ischemic conditions. Because angiogenesis may occur in the absence of ischemia, it remains to be determined whether and how β-adrenergic signaling regulates angiogenesis, which develops under normoxic conditions. The effect of β-adrenergic ligands on angiogenesis was investigated using 3-dimensional cultures of mouse aortic rings embedded in collagen type I, in which luminized microvessels develop in response to vascular endothelial growth factor (VEGF). Under normoxic conditions, both isoproterenol, a β-adrenergic receptor (β-AR) agonist, and forskolin, an adenylate cyclase activator, were unable to influence aortic microvessel sprouting. On the contrary, treatment with propranolol, a β-AR antagonist, caused an approximately 70% increase in VEGF-mediated microvessel sprouting. This effect was abolished in rings from both double β-AR and β1-AR knockout mice, but not in rings from β2-AR knockout mice. Significant increases in microvessel sprouting were also observed when mouse aortic rings from C57BL/6 mice were treated with the β1-AR-selective antagonists metoprolol and bisoprolol or with the β2-AR-selective antagonist ICI 118,551. Conversely, carvedilol, a nonselective β-AR antagonist, was unable to affect aortic sprouting. These findings suggest that some β-blockers display proangiogenic activity through a mechanism that is independent of their ability to antagonize catecholamine action. The present results also identify a new function for β-AR signaling as a facilitator for VEGF-mediated angiogenesis and have implications for understanding the mechanisms that regulate angiogenic responses under normoxic conditions.

Clinical efficacy of propranolol in the treatment of hemangioma and changes in serum VEGF, bFGF and MMP-9

The aim of this study was to observe the clinical efficacy and safety of propranolol in the treatment of hemangioma, and to reveal its possible mechanism. A total of 129 cases of proliferative hemangioma were divided into two groups: i) Treatment (n=97), in which the patients received oral propranolol therapy and ii) observation (n=32), in which the patients underwent clinical observation. The changes in the hemangiomas were noted and compared between the two groups. In addition, the heart rate, blood glucose levels, liver, kidney and thyroid function of the patients in the treatment group were monitored prior to and following treatment; the ELISA method was used for the measurement of the patients' serum concentrations of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and matrix metalloproteinase-9 (MMP-9) at the same time-points. A significant difference in curative effect was found between the treatment and observation group. The concentration of free thyroxine and sensitive thyroid-stimulating hormone and the heart rate of the treatment group exhibited significant changes prior to and following medication, but no statistical significance was found in the changes in blood glucose, liver and kidney function and free triiodothyronine concentration. Furthermore, the serum concentrations of VEGF, bFGF and MMP-9 in the treatment group 8 weeks after medication were decreased significantly compared with those before treatment. In conclusion, oral propranolol has a good curative effect in the treatment of proliferative hemangioma, with few side effects and a high level of safety. The mechanism underlying the effects of propranolol may be associated with the downregulation of VEGF, bFGF and MMP-9 expression.

The Whitening of Brown Fat and Its Implications for Weight Management in Obesity

Systemic inflammation resulting from dysfunction of white adipose tissue (WAT) accelerates the pathologies of diabetes and cardiovascular diseases. In contrast to WAT, brown adipose tissue (BAT) is abundant in mitochondria that produce heat by uncoupling respiratory chain process of ATP synthesis. Besides BAT's role in thermogenesis, accumulating evidence has shown that it is involved in regulating systemic metabolism. Studies have analyzed the "browning" processes of WAT as a means to combat obesity, whereas few studies have focused on the impact and molecular mechanisms that contribute to obesity-linked BAT dysfunction--a process that is associated with the "whitening" of this tissue. Compared to WAT, a dense vascular network is required to support the high energy consumption of BAT. Recently, vascular rarefaction was shown to be a significant causal factor in the whitening of BAT in mouse models. Vascular insufficiency leads to mitochondrial dysfunction and loss in BAT and contributes to systemic insulin resistance. These data suggest that BAT "whitening," resulting from vascular dysfunction, can impact obesity and obesity-linked diseases. Conversely, agents that promote BAT function could have utility in the treatment of these conditions.

Pathological hypertrophy reverses β2-adrenergic receptor-induced angiogenesis in mouse heart

β-adrenergic activation and angiogenesis are pivotal for myocardial function but the link between both events remains unclear. The aim of this study was to explore the cardiac angiogenesis profile in a mouse model with cardiomyocyte-restricted overexpression of β₂-adrenoceptors (β₂-TG), and the effect of cardiac pressure overload. β₂-TG mice had heightened cardiac angiogenesis, which was essential for maintenance of the hypercontractile phenotype seen in this model. Relative to controls, cardiomyocytes of β₂-TGs showed upregulated expression of vascular endothelial growth factor (VEGF), heightened phosphorylation of cAMP-responsive-element-binding protein (CREB), and increased recruitment of phospho-CREB, CREB-binding protein (CBP), and p300 to the VEGF promoter. However, when hearts were subjected to pressure overload by transverse aortic constriction (TAC), angiogenic signaling in β₂-TGs was inhibited within 1 week after TAC. β₂-TG hearts, but not controls, exposed to pressure overload for 1–2 weeks showed significant increases from baseline in phosphorylation of Ca²⁺/calmodulin-dependent kinase II (CaMKIIδ) and protein expression of p53, reduction in CREB phosphorylation, and reduced abundance of phospho-CREB, p300 and CBP recruited to the CREB-responsive element (CRE) site of VEGF promoter. These changes were associated with reduction in both VEGF expression and capillary density. While non-TG mice with TAC developed compensatory hypertrophy, (₂-TGs exhibited exaggerated hypertrophic growth at week-1 post-TAC, followed by LV dilatation and reduced fractional shortening measured by serial echocardiography. In conclusion, angiogenesis was enhanced by the cardiomyocyte (₂AR/CREB/VEGF signaling pathway. Pressure overload rapidly inhibited this signaling, likely as a consequence of activated CaMKII and p53, leading to impaired angiogenesis and functional decompensation.

The effect of depression on serum VEGF level in Alzheimer's disease

Objective. Growing evidence suggests that angiogenesis might represent a new pathogenic mechanism involved in the progression of Alzheimer's disease (AD). Among angiogenic cytokines, vascular endothelial growth factor (VEGF) levels in AD patients have been evaluated, but the results are controversial among studies. We investigated serum levels of VEGF in AD patients with depression, AD patients without depression, and the controls, respectively. The aim of this study is to elucidate the relationship between VEGF, depression, and cognitive impairment in AD. Methods. The CDR (Clinical Dementia Rating), MMSE-KC (the Mini-Mental Status Examination-Korean version), and SGDS-K (the Korean version of the Geriatric Depression Scale-Short Form) were measured in the subjects. Serum VEGF levels were measured in 24 AD patients with depression, 25 AD patients without depression, and 26 controls, using an enzyme-linked immunosorbent assay kit. Results. Serum VEGF levels in AD patients with depression were significantly higher than AD patients without depression or the control. A correlation was observed between VEGF and scores on SGDS-K, but no correlation was detected between VEGF and MMSE-KC scores. Conclusion. Serum VEGF levels in AD patients with depression were higher than those without depression. Depression might be associated with changes in serum levels of VEGF in AD patients.

Role of the autonomic nervous system in tumorigenesis and metastasis

Convergence of multiple stromal cell types is required to develop a tumorigenic niche that nurtures the initial development of cancer and its dissemination. Although the immune and vascular systems have been shown to have strong influences on cancer, a growing body of evidence points to a role of the nervous system in promoting cancer development. This review discusses past and current research that shows the intriguing role of autonomic nerves, aided by neurotrophic growth factors and axon cues, in creating a favorable environment for the promotion of tumor formation and metastasis.

3,5-Diiodo-L-thyronine activates brown adipose tissue thermogenesis in hypothyroid rats

3,5-Diiodo-l-thyronine (T2), a thyroid hormone derivative, is capable of increasing energy expenditure, as well as preventing high fat diet-induced overweight and related metabolic dysfunction. Most studies to date on T2 have been carried out on liver and skeletal muscle. Considering the role of brown adipose tissue (BAT) in energy and metabolic homeostasis, we explored whether T2 could activate BAT thermogenesis. Using euthyroid, hypothyroid, and T2-treated hypothyroid rats (all maintained at thermoneutrality) in morphological and functional studies, we found that hypothyroidism suppresses the maximal oxidative capacity of BAT and thermogenesis, as revealed by reduced mitochondrial content and respiration, enlarged cells and lipid droplets, and increased number of unilocular cells within the tissue. In vivo administration of T2 to hypothyroid rats activated BAT thermogenesis and increased the sympathetic innervation and vascularization of tissue. Likewise, T2 increased BAT oxidative capacity in vitro when added to BAT homogenates from hypothyroid rats. In vivo administration of T2 to hypothyroid rats enhanced mitochondrial respiration. Moreover, UCP1 seems to be a molecular determinant underlying the effect of T2 on mitochondrial thermogenesis. In fact, inhibition of mitochondrial respiration by GDP and its reactivation by fatty acids were greater in mitochondria from T2-treated hypothyroid rats than untreated hypothyroid rats. In vivo administration of T2 led to an increase in PGC-1α protein levels in nuclei (transient) and mitochondria (longer lasting), suggesting a coordinate effect of T2 in these organelles that ultimately promotes net activation of mitochondrial biogenesis and BAT thermogenesis. The effect of T2 on PGC-1α is similar to that elicited by triiodothyronine. As a whole, the data reported here indicate T2 is a thyroid hormone derivative able to activate BAT thermogenesis.

Cyclic Adenosine Monophosphate-Mediated Enhancement of Vascular Endothelial Growth Factor Released by Differentiated Human Monocytic Cells: The Role of Protein Kinase A

OBJECTIVE

Our investigation was designed to examine the signaling pathway involved in the enhancement of vascular endothelial growth factor (VEGF) release by β-adrenoceptor agonists.

MATERIALS AND METHODS

Human U937 cells differentiated into macrophages were primed with lipopolysaccharide (LPS) in the absence or presence of β-adrenoceptor agonists and antagonists. The VEGF released and the intracellular cyclic adenosine monophosphate (cAMP) generated were assayed by ELISA. Where necessary, differences between mean values were tested for significance using Student's t test.

RESULTS

Isoprenaline, procaterol and salbutamol concentration-dependently enhanced the release of VEGF induced by LPS in U937 cells. R*,R*-(±)-4-[2-[(2-(3-chlorophenyl)-2-hydroxyethyl)amino]propyl]phenoxyacetic acid (BRL 37344), a selective β3-adrenoceptor agonist, did not enhance VEGF release. Using isoprenaline as an agonist, propranolol, ICI 118551 and atenolol produced a parallel rightward shift of the concentration-response curve with no reduction in the maximum response. The -logKB values were 8.12 ± 0.17, 8.03 ± 0.05 and 7.23 ± 0.05 for propranolol, ICI 118551 and atenolol, respectively, indicating the possible involvement of both β1- and β2-adrenoceptor subtypes. Isoprenaline and prostaglandin E2 concentration-dependently increased cAMP generation in U937 cells. Isoprenaline, db-cAMP and 6-Bnz-cAMP, a protein kinase A (PKA) activator, all enhanced VEGF release induced by LPS, and this effect was abolished by KT 5720 and Rp-cAMPS, which are both selective PKA inhibitors, suggesting that PKA is the downstream effector of cAMP activity. 8-CPT-cAMP, a selective activator of the Epac system, had no effect on VEGF release induced by LPS, indicating that the Epac pathway played no role in the release process.

CONCLUSION

In this study, we established that β1- and β2- but not β3-adrenoceptors mediated cAMP-dependent enhancement of VEGF release induced by LPS in differentiated U937 cells, and that PKA was the downstream effector of cAMP activity.