PPARβ/δ a potential target in pulmonary hypertension blighted by cancer risk

Pharmacological Utility of PPAR Modulation for Angiogenesis in Cardiovascular Disease

Peroxisome proliferator activated receptors, including PPARα, PPARβ/δ, and PPARγ, are ligand-activated transcription factors belonging to the nuclear receptor superfamily. They play important roles in glucose and lipid metabolism and are also supposed to reduce inflammation and atherosclerosis. All PPARs are involved in angiogenesis, a process critically involved in cardiovascular pathology. Synthetic specific agonists exist for all PPARs. PPARα agonists (fibrates) are used to treat dyslipidemia by decreasing triglyceride and increasing high-density lipoprotein (HDL) levels. PPARγ agonists (thiazolidinediones) are used to treat Type 2 diabetes mellitus by improving insulin sensitivity. PPARα/γ (dual) agonists are supposed to treat both pathological conditions at once. In contrast, PPARβ/δ agonists are not in clinical use. Although activators of PPARs were initially considered to have favorable effects on the risk factors for cardiovascular disease, their cardiovascular safety is controversial. Here, we discuss the implications of PPARs in vascular biology regarding cardiac pathology and focus on the outcomes of clinical studies evaluating their benefits in cardiovascular diseases.

Peroxisome Proliferator-Activated Receptors and the Hallmarks of Cancer

Peroxisome proliferator-activated receptors (PPARs) function as nuclear transcription factors upon the binding of physiological or pharmacological ligands and heterodimerization with retinoic X receptors. Physiological ligands include fatty acids and fatty-acid-derived compounds with low specificity for the different PPAR subtypes (alpha, beta/delta, and gamma). For each of the PPAR subtypes, specific pharmacological agonists and antagonists, as well as pan-agonists, are available. In agreement with their natural ligands, PPARs are mainly focused on as targets for the treatment of metabolic syndrome and its associated complications. Nevertheless, many publications are available that implicate PPARs in malignancies. In several instances, they are controversial for very similar models. Thus, to better predict the potential use of PPAR modulators for personalized medicine in therapies against malignancies, it seems necessary and timely to review the three PPARs in relation to the didactic concept of cancer hallmark capabilities. We previously described the functions of PPAR beta/delta with respect to the cancer hallmarks and reviewed the implications of all PPARs in angiogenesis. Thus, the current review updates our knowledge on PPAR beta and the hallmarks of cancer and extends the concept to PPAR alpha and PPAR gamma.

Anabolic steroid misuse and male infertility: management and strategies to improve patient awareness

Introduction: Anabolic androgenic steroid use is an uncommon but important cause of male infertility. As paternal age and anabolic steroid use increases, providers are more likely than ever to encounter men with infertility and prior or concurrent anabolic steroid use. In this review, we outline the background, epidemiology and pathophysiology of anabolic steroid induced male infertility and provide recommendations regarding the diagnosis, management, and future prevention of this condition.Areas covered: Male reproductive physiology is a tightly regulated process that can be influenced by exogenous sources such as anabolic steroids and selective androgen receptor modulators (SARMs). Data suggest that a combination of selective estrogen receptor modulators (SERMs), human chorionic gonadotropin (hCG), aromatase inhibitors (AIs), and recombinant follicle-stimulating hormone (rFSH) may lead to spermatogenesis recovery.Expert opinion: Anabolic steroid and SARM users continue to exhibit lack of understanding regarding the potential side effects of their use on male fertility. Current literature suggests that spermatogenesis can be safely recovered using a combination of SERMs, hCG, AIs and rFSH although additional studies are necessary. While anabolic steroid prevention strategies have largely been focused on the individual level, further investigation is necessary and should be approached in a socioecological manner.

PPARs and Myocardial Infarction

Peroxisome proliferator-activated receptors (PPARs) belong to the nuclear hormone receptor family. They are ligand-activated transcription factors and exist in three different isoforms, PPARα (NR1C1), PPARβ/δ (NR1C2), and PPARγ (NR1C3). PPARs regulate a variety of functions, including glucose and lipid homeostasis, inflammation, and development. They exhibit tissue and cell type-specific expression patterns and functions. Besides the established notion of the therapeutic potential of PPAR agonists for the treatment of glucose and lipid disorders, more recent data propose specific PPAR ligands as potential therapies for cardiovascular diseases. In this review, we focus on the knowledge of PPAR function in myocardial infarction, a severe pathological condition for which therapeutic use of PPAR modulation has been suggested.

A sentinel population: The public health benefits of monitoring enhanced body builders

There is heightened recognition of the public health implications of anabolic androgenic steroids (AAS) for the use of image and performance enhancement; with increasing evidence of their long-term negative health impacts, the hazards associated with their administration (often via injection), and the variability and unpredictability of their contents. In order to optimise the effects of these drugs, together with strict dietary and training regimes, AAS users typically supplement their use with an expansive and continually evolving range of ancillary drugs. The discovery and subsequent adoption of these drugs by the broader AAS user population is largely dependent upon a minority of social influencers within the bodybuilding community. Pioneering enhanced bodybuilders who self-experiment with a diverse range of image and performance enhancing drugs (IPEDs) and ancillary drugs have been the forerunners in the development of an underground user-led literature, online discussion forums, and were early adopters of internet-facilitated drug markets. Yet the impact of their self-experimentations extends well beyond the enhanced bodybuilding community, particularly in their use of ancillary drugs. Most significantly has been their role in the diffusion of various enhancement and psychoactive drugs to the wider population. Using the theoretical framework of the 'diffusion of innovation' we consider the role that pioneering enhanced bodybuilders have played in the diffusion of various enhancement and psychoactive drugs to the wider population through a focus on three substances: dinitrophenol (DNP), melanotan II and gamma-hydroxybtyrate (GHB). With an increasing range of drugs used by bodybuilders, coupled with an expansion in the use of online forums and online platforms to purchase pharmacological and new psychoactive drugs, we anticipate this trend of diffusion amongst the wider population will continue to flourish. Therefore, we highlight the need for policy makers to monitor emergent trends, not only in the general AAS population but particularly amongst enhanced bodybuilders.

Vascular PPARβ/δ Promotes Tumor Angiogenesis and Progression

Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors, which function as transcription factors. Among them, PPARβ/δ is highly expressed in endothelial cells. Pharmacological activation with PPARβ/δ agonists had been shown to increase their angiogenic properties. PPARβ/δ has been suggested to be involved in the regulation of the angiogenic switch in tumor progression. However, until now, it is not clear to what extent the expression of PPARβ/δ in tumor endothelium influences tumor progression and metastasis formation. We addressed this question using transgenic mice with an inducible conditional vascular-specific overexpression of PPARβ/δ. Following specific over-expression of PPARβ/δ in endothelial cells, we induced syngenic tumors. We observed an enhanced tumor growth, a higher vessel density, and enhanced metastasis formation in the tumors of animals with vessel-specific overexpression of PPARβ/δ. In order to identify molecular downstream targets of PPARβ/δ in the tumor endothelium, we sorted endothelial cells from the tumors and performed RNA sequencing. We identified platelet-derived growth factor receptor beta (Pdgfrb), platelet-derived growth factor subunit B (Pdgfb), and the tyrosinkinase KIT (c-Kit) as new PPARβ/δ -dependent molecules. We show here that PPARβ/δ activation, regardless of its action on different cancer cell types, leads to a higher tumor vascularization which favors tumor growth and metastasis formation.