Peter I. Ghenev

Adipobiology of Disease: Adipokines and Adipokine-Targeted Pharmacology

In recent years, the simple paradigm of adipose tissue as merely a fat store is rapidly evolving into a complex paradigm of this tissue as multipotential secretory organ, partitioned into a few large depots, including visceral and subcutaneous location, and many small depots, associated with a variety of organs in the human body. The major secretory compartment of adipose tissue consists of adipocytes, fibroblasts, and mast cells. These cells, using endocrine, paracrine and autocrine pathways, secrete multiple bioactive molecules, conceptualized as adipokines or adipocytokines. This review examines current information in adipobiology of various diseases besides obesity and related diseases such as type 2 diabetes, metabolic syndrome, and cardiovascular disease. Finally, we emphasize the possibilities for adipokine-targeted pharmacology in adiponectin (Acrp30, apM1, AdipoQ, GBP28), angiotensin II, estrogens, nerve growth factor, tumor necrosis factor-alpha, and also adipose mast cells.

Neurotrophin presence in human coronary atherosclerosis and metabolic syndrome: a role for NGF and BDNF in cardiovascular disease?

The development of atherosclerotic cardiovascular disease is a common comorbidity in patients with the metabolic syndrome, a concurrence of cardiovascular risk factors in one individual. While multiple growth factors and adipokines are identified in atherosclerotic lesions, as well as neurotrophins implicated in both cardiac ischemia and lipid and glucose metabolism, the potential role of neurotrophins in human coronary atherosclerosis and in the metabolic syndrome still remains to be elucidated. Here we describe and discuss our results that represent a novel attempt to study the cardiovascular and metabolic biology of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and mast cells (MC). The local amount of NGF, the immunolocalization of p75 neurotrophin receptor (p75NTR) and the number of MC were correlatively examined in coronary vascular wall and in the surrounding subepicardial adipose tissue, obtained from autopsy cases in humans with advanced coronary atherosclerosis. We also analyzed the plasma levels of NGF, BDNF and leptin and the number of MC in biopsies from abdominal subcutaneous adipose tissue in patients with a severe form of the metabolic syndrome. The results demonstrate that NGF levels are decreased in atherosclerotic coronary vascular tissue but increased in the subepicardial adipose tissue, whereas both tissues express a greater number of MC and a stronger p75NTR immunoreactivity, compared to controls. Metabolic syndrome patients display a significant hyponeurotrophinemia and an increased number of adipose MC; the later correlates with elevated plasma leptin levels. In effect, we provide the first evidence for (i) an altered presence of NGF, p75NTR and MC in both coronary vascular and subepicardial adipose tissue in human coronary atherosclerosis, and (ii) a significant decrease in plasma NGF and BDNF levels and an elevated amount of plasma leptin and adipose MC in metabolic syndrome patients. Together our findings suggest that neuroimmune mediators such as NGF, BDNF, leptin and MC may be involved in the development of cardiovascular disease and related disorders.

Nerve growth factor levels and mast cell distribution in human coronary atherosclerosis

Nerve growth factor (NGF), in addition to its neurotrophic function, acts on a variety of non-neuronal cells including immune cells and vascular smooth muscle cells. The aim of the present study was to determine the NGF levels and the distribution of NGF and low-affinity NGF receptor (p75NGFR) and mast cells (MC) in human atherosclerotic coronary arteries. Specimens of human coronary arteries obtained from autopsy cases (n=12, subjects with atherosclerotic lesions; n=9, subjects without atherosclerotic lesions/controls) were used. The present study showed that in the atherosclerosis-lesioned arteries, the amount of NGF decreased, whereas the expression of p75NGFR immunoreactivity and the number, both of MC and vasa vasorum, particularly in the adventitia, significantly increased, compared with the control arteries. Cumulatively, our findings help to set the neurotrophic theory and its currently extended neuroimmune framework into the context of pathobiology of atherosclerosis, suggesting that altered presence of NGF, p75NGFR, and MC may play a role in neuroimmune mechanisms of human coronary atherosclerosis.

Adipoparacrinology - Vascular periadventitial adipose tissue (Tunica adiposa) as an example

Human adipose tissue is partitioned into two large depots (subcutaneous and visceral), and many small depots associated with internal organs, e.g. heart, blood vessels, major lymph nodes, pancreas, prostate gland and ovaries. Since the adipose ‘Big Bang’ led to the discovery of leptin (Zhang, Proenca, Maffei, Barone, Leopold and Friedman, Nature 1994;372:425–32), adipose tissue has been seen not merely as a lipid store, but as a secretory – endocrine and paracrine – organ, particularly in the pathogenesis of a number of diseases. Accordingly, two major sub‐fields of adipobiology have emerged, viz. adipoendocrinology and adipoparacrinology, the latter herein being illustrated by PAAT (periadventitial adipose tissue) in vascular walls. A long‐standing paradigm holds that the vascular wall consists of three coats, tunica intima, tunica media and tunica adventitia. It is now imperative that ‘to further elucidate vascular function, we should no longer, as hitherto, separate adventitia and PAAT from the vascular wall, but keep them attached and in place, and subject to thorough examination’ (Chaldakov, Fiore, Ghenev, Stankulov and Aloe, Int Med J 2000;7:43–9; Chaldakov, Stankulov and Aloe, Atherosclerosis 2001;154:237–8; Chaldakov GN, Stankulov IS, Fiore M, Ghenev PI and Aloe L, Atherosclerosis 2001;159:57–66). From the available data, we propose that it is time to rethink about vascular wall composition, and suggest that the PAAT may be considered the fourth and outermost vascular coat, hence, tunica adiposa (regarding the proximal segment of coronary artery, it is the innermost part of the EAT (epicardial adipose tissue) situated around the coronary adventitia). Its significance in the pathogenesis and therapy of CMDs (cardiometabolic diseases), particularly atherosclerosis and hypertension, requires further basic, translational and clinical studies.

Triactome: Neuro–Immune–Adipose Interactions. Implication in Vascular Biology

Understanding how the precise interactions of nerves, immune cells, and adipose tissue account for cardiovascular and metabolic biology is a central aim of biomedical research at present. A long standing paradigm holds that the vascular wall is composed of three concentric tissue coats (tunicae): intima, media, and adventitia. However, large- and medium-sized arteries, where usually atherosclerotic lesions develop, are consistently surrounded by periadventitial adipose tissue (PAAT), we recently designated tunica adiposa (in brief, adiposa like intima, media, and adventitia). Today, atherosclerosis is considered an immune-mediated inflammatory disease featured by endothelial dysfunction/intimal thickening, medial atrophy, and adventitial lesions associated with adipose dysfunction, whereas hypertension is characterized by hyperinnervation-associated medial thickening due to smooth muscle cell hypertrophy/hyperplasia. PAAT expansion is associated with increased infiltration of immune cells, both adipocytes and immunocytes secreting pro-inflammatory and anti-inflammatory (metabotrophic) signaling proteins collectively dubbed adipokines. However, the role of vascular nerves and their interactions with immune cells and paracrine adipose tissue is not yet evaluated in such an integrated way. The present review attempts to briefly highlight the findings in basic and translational sciences in this area focusing on neuro–immune–adipose interactions, herein referred to as triactome. Triactome-targeted pharmacology may provide a novel therapeutic approach in cardiovascular disease.

Cell biology of glioblastoma multiforme: from basic science to diagnosis and treatment

First described in the 1800s, glioblastoma multiforme (GBM), a class IV neoplasm with astrocytic differentiation, as per the revised 2016 World Health Organization classification of tumors of the central nervous system (CNS) is the most common malignant tumor of the CNS. GBM has an extremely wide set of alterations, both genetic and epigenetic, which yield a great number of mutation subgroups, some of which have an established role in independent patient survival and treatment response. All of those components not only represent a closed cycle but are also relevant to the tumor biological behavior and resistance to treatment as they form the pathobiological behavior and clinical course. The presence of different triggering mutations on the background of the presence of key mutations in the GBM stem cells (GBMsc) further separates GBM as primary arising de novo from neural stem cell precursors developing into GBMsc and secondary, by means of aggregated mutations. Some of the change in cellular biology in GBM can be observed via light microscope as they form the cellular and tissue hallmarks of the condition. Changes in genetic information, resulting in alteration, suppression and expression of genes compared to their physiological levels in healthy astrocytes lead to not only cellular, but also extracellular matrix reorganization. These changes result in a multiform number of micromorphological and purely immunological/biochemical forms. Therefore, in the twenty-first century the term multiforme, previously outcast from nomenclatures, has gained new popularity on the background of genotypic diversity in this neoplastic entry.

Serum levels of RIPK3 and troponin I as potential biomarkers for predicting impaired left ventricular function in patients with myocardial infarction with ST segment elevation and normal troponin I levels prior percutaneous coronary intervention

The current study examined the serum levels of receptor-interacting protein kinase 3 (RIPK3) in 51 patients with New York Heart Association (NYHA) class III-IV heart failure, 53 patients with myocardial infarction with ST elevation (STEMI), and 19 healthy subjects serving as a control group. An enzyme-linked immunoadsorbent assay (ELISA) was used to measure the levels of RIPK3 expression in serum. The area under the receiver operating characteristic curve (AUC) was then used to evaluate the predictive performance of RIPK3 and troponin I in patients with STEMI. In patients with normal levels of troponin I prior to percutaneous coronary intervention (PCI), serum levels of RIPK3 and troponin I after PCI were sufficient to differentiate patients with a preserved left ventricular ejection fraction (LVEF) from those with impaired left ventricular function after PCI (AUC = 0.780 (95% CI: 0.565-0.995, p = 0.043) with a sensitivity of 76.9% and a specificity of 71.4% vs. AUC = 0.735 (95% CI: 0.530-0.941, p = 0.038) with a sensitivity of 88.2% and a specificity of 63.6% at the optimal cutoff values, respectively). Moreover, elevated levels of troponin I after PCI were associated with an increased risk of an LVEF < 50% prior to discharge (odds ratio, 1.014; 95 % CI, 1.001 to 1.027; p = 0.03), while elevated levels of RIPK3 were not associated with such a risk. The current findings suggest that in patients with normal levels of troponin I prior to PCI, serum levels of RIPK3 and troponin I can serve as a potential marker to identify patients with a decreased LVEF, thus possibly allowing an early shift to more intensive therapy.

Quantitative Analysis of Tumor-associated Tissue Eosinophilia in Recurring Bladder Cancer

The relatively high incidence of recurrence of bladder cancer is a serious problem in clinical practice. At present, there are no objective microscopic criteria for evaluation of the tendency for local relapse. Besides the phenotypic properties of the tumor parenchymal cells, possible signs in regard to recurrence could also be derived from the peculiarities of the tumor stroma. The stromal reaction, manifested by inflammatory infiltration in the tumor is considered to influence the biological behavior of tumors. Also, a relationship has been reported between the number of eosinophils and the survival of patients. The aim of the present study is to analyze tumor-associated tissue eosinophilia (TATE) and to compare TATE density in the initial foci of age and gender-matched 156 cases of recurrent and non-recurrent bladder cancers; the tumors that have relapsed within six months after removal and contained statistically significant greater numbers of eosinophils in primary cancer sites. These results suggest that TATE may be one of the probable prognostic signs for local relapse of urothelial cancer.

A Comparative Review of Demographics, Incidence, and Epidemiology of Histologically Confirmed Intracranial Tumors in Brazil and Bulgaria

Intracranial tumors (ICTs) attract numerous scientific teams and tremendous financial resources worldwide. These lesions of the central nervous system (CNS) can be both benign and malignant in biological behavior as well as local or metastatic in origin. We compared data from two studies on primary and metastatic ICTs from Brazil and Bulgaria, based on histopathologically confirmed ICTs from tertiary health centers. Primary ICTs significantly outweigh the frequency of metastatic ICTs. Primary ICTs represent 86.45% in Brazil and 69.17% in Bulgaria, with around 60% of their totals being malignant. There is a statistical dominance of tumors from the neuroepithelial origin, with the most common entry being glioblastoma multiforme. The second-most common primary ICT group comprises tumors of meningeal origin. Metastatic ICTs show great variance; 13.55% in Brazil and 31.38% in Bulgaria of all ICT cases being attributed to them. However, metastatic ICTs are even a more diverse group than neuroepithelial tumors, with the majority of this group comprising metastatic colorectal adenocarcinoma (almost exclusively in males), metastatic breast adenocarcinoma in females, metastatic pulmonary carcinomas (primarily from the non-small cell group with a male predominance), and metastatic melanoma with an even gender ratio.

The Diagnostic Dilemma of Epithelial Marker Expression in Glioblastoma

To the Editor, Glioblastoma Multiforme (GBM) is a hot topic for research as the intimacies of this type of malignancy seem to be a long way from being truly understood. Diagnostically however, despite decades of research and many attempts at standardizing the histopathological diagnostic process, GBM remains an entry to be diagnosed by experienced neuropathologists. A key point in the pathological diagnostic process is the immunohistochemical (IHC) phenotypisation of tumor samples. While some glial specific IHC markers such as glial fibrillary acidic protein (GFAP) give a constant positive reaction, and are used as a diagnostic medium in GBM, there is a wide panel of IHC markers that give positive IHC reactions with GBM tissue samples. Some of these such as Vimentin are very unspecific and are mainly used as a positive control for IHC reactions, but can also be used in some instances to distinguish between epithelial and non-epithelial tumors. Some IHC markers, such as cytokeratin (CK) AE1/AE3 and epithelial membrane antigen (EMA) are highly specific to epithelial cells, but can very often give positive IHC reaction with GBM tumor tissue, producing a diagnostic dilemma (Figs. 1 and 2) [1–5]. Terada (2015) reported positive IHC expression of several types of keratin antibodies, especially for the CKAE1/AE3 antibody, confirming the findings reported by other similar studies [1–3]. Terada also stated that this positivity is due to the production of keratin proteins from GBM cells, but this statement is not supported by anything more than IHC investigations [1]. However, IHC is not the most specific immunology based test and a phenotypically positive tissue sample on IHC may not truly express the antigens tested due to conformational mimicry between the antibody and a similar epitope in another antigen. Such is the case with keratins and perhaps also with other epithelial markers, such as EMA, in GBM [2–5]. Whilst many authors and practicing pathologists believe that IHC is a full proof testing method and that a high number of GBM cases express some type of keratin molecules, especially the epitheloid and giant-cell GBM subtypes. This is not entirely true, as demonstrated by Kriho et al. in 1997 in a comparative study of keratin expression in GBM [2]. She concluded that the AE3 fraction of the CKAE1/AE3 antibody cocktail is the one that reacts with an antigen in GBM cells, however in immunoblot and electrophoresis test a protein with the characteristics of keratin filaments was not detected [2]. Therefore, Kriho suggested that these IHC false positive results are caused by a three-dimensional conformational mimicry with another intermediate cytoskeletal protein such as the dysmorphic GFAP produced by the neoplastic astrocytes [2]. Although the result of Kriho et al. have not been recreated since, the specifics of a Western immunoblot test highly outweigh those of IHC and are used in explaining the GBM-CK AE1/AE3 phenomena by a number of authors [2–4]. Some * George Stoyanov georgi.geesh@gmail.com