Exercise-induced ‘browning’ of adipose tissues

Global rates of obesity continue to rise and are necessarily the consequence of a long-term imbalance between energy intake and energy expenditure. This is the result of an expansion of adipose tissue due to both the hypertrophy of existing adipocytes and hyperplasia of adipocyte precursors. Exercise elicits numerous physiological benefits on adipose tissue, which are likely to contribute to the associated cardiometabolic benefits. More recently it has been demonstrated that exercise, through a range of mechanisms, induces a phenotypic switch in adipose tissue from energy storing white adipocytes to thermogenic beige adipocytes. This has generated the hypothesis that the process of adipocyte ‘browning’ may partially underlie the improved cardiometabolic health in physically active populations. Interestingly, ‘browning’ also occurs in response to various stressors and could represent an adaptive response. In the context of exercise, it is not clear whether the appearance of beige adipocytes is metabolically beneficial or whether they occur as a transient adaptive process to exercise-induced stresses. The present review discusses the various mechanisms (e.g. fatty acid oxidation during exercise, decreased thermal insulation, stressors and angiogenesis) by which the exercise-induced ‘browning’ process may occur

Association of gene polymorphism of H and B complement pathway factors in age-related macular degeneration

Age-related macular degeneration (AMD) is a leading cause of irreversible blindness in the elderly population. The purpose this study was to test for possible association between 6 SNPs spanning the CFH gene as well as 4 SNPs from the chromosome 10 region in a cohort from central Greece. AMD individuals were recruited among patients attending the Macular Clinic at the Ophthalmology Department of the University Hospital of Larissa. The control group consisted of age and sex matched individuals without clinical evidence of macular disease. A total of 16 SNPs were genotyped in a cohort comprising of 239 control subjects, 77 subjects with dry AMD (AREDS 2 and 3), 16 subjects with geographic atrophy, and 143 subjects with neovascular AMD. Females were 54.7% of the patients and 54.4% of the controls. Mean age of patients and controls was 75.4±7.7 and 79±7.2 respectively. Four SNPs were significantly associated with increased risk of both neovascular AMD and all AMD subtypes: the CFH SNPs rs1061170 and rs35292876, and the 10q26 SNPs rs10490924 and rs11200638. The CFH SNPs rs800292 and rs2284664 were shown to significantly decrease risk of both neovascular AMD and all AMD subtypes. Only one SNP, CFH rs1061170 (Y402H) was associated with dry AMD. Specifically, the C allele was shown to increase risk of dry AMD by 2.17 fold. These associations remained significant after adjustment for age, sex, and smoking. The CFH SNP rs1065489 and the complement pathway SNPs in C2, CFB, and C3 were not significantly associated with AMD in any analysis. The findings of the present study provide evidence that CFH gene variants play a major role in the genetic susceptibility to AMD in a Greek population. These findings are of direct relevance for disease and help mapping the genetic chart of AMD.H ηλικιακή εκφύλιση της ωχράς κηλίδας (ΗΕΩ) είναι η κύρια αιτία μη αναστρέψιμης τύφλωσης στον πληθυσμό των ηλικιωμένων. Ο σκοπός αυτής της μελέτης ήταν να διερευνηθεί η πιθανή συσχέτιση μεταξύ 6 SNPs που καλύπτουν το γονίδιο CFH καθώς και 4 SNPs από την περιοχή του χρωμοσώματος 10 σε μία κοορτή από την κεντρική Ελλάδα. Τα άτομα με ΗΕΩ επιλέχτηκαν μεταξύ των ασθενών στην κλινική της ωχράς κηλίδας στο Τμήμα Οφθαλμολογίας του Πανεπιστημιακού Νοσοκομείου Λάρισας. Η ομάδα ελέγχου αποτελείτο από ίδιας ηλικίας και φύλου άτομα χωρίς κλινικές ενδείξεις της νόσου της ωχράς κηλίδας. Συνολικά ελέγχθησαν 16 SNPs γονότυποι σε μια ομάδα που αποτελούνταν από 239 άτομα-μάρτυρες, 77 άτομα με ξηρά ΗΕΩ(AREDS 2 και 3), 16 άτομα με γεωγραφική ατροφία, και 143 άτομα με νεοαγγειακή ΗΕΩ. Γυναίκες ήταν 54,7% των ασθενών και 54,4% της ομάδας ελέγχου. Η μέση ηλικία των ασθενών και της ομάδας ελέγχου ήταν 75,4 ± 7,7 και 79 ± 7,2 έτη αντίστοιχα. Τέσσερις SNPs σχετίζονταν σημαντικά με αυξημένο κίνδυνο τόσο για νεοαγγειακή ΗΕΩ, όσο και όλων των υποτύπων της ΗΕΩ: οι rs1061170 CFH SNPs και rs35292876, και οι 10q26 SNPs rs10490924 και rs11200638. Οι rs800292 CFH SNPs και rs2284664 δείχτηκε ότι μειώνουν σημαντικά τον κίνδυνο τόσο για νεοαγγειακή ΗΕΩ, όσο και για όλους τους υποτύπους της ΗΕΩ. Μόνο ένας SNP, ο rs1061170 CFH (Y402H) συνδέθηκε με την ξηρά ΗΕΩ. Συγκεκριμένα, το αλληλόμορφο C δείχθηκε ότι αυξάνει τον κίνδυνο της ξηρής ΗΕΩ κατά 2,17 φορές. Αυτοί οι συσχετισμοί παρέμειναν σημαντικοί μετά από προσαρμογή για την ηλικία, το φύλο, και το κάπνισμα. Οι rs1065489 CFH SNP και οι SNPs της οδού του συμπληρώματος σε C2, CFB, και C3 δε σχετίζονταν σημαντικά με την ΗΕΩ σε καμία ανάλυση. Τα ευρήματα της παρούσας μελέτης δείχνουν ότι οι γονιδιακές παραλλαγές CFH διαδραματίζουν σημαντικό ρόλο στην γενετική προδιάθεση για την ΗΕΩ στον ελληνικό πληθυσμό. Τα ευρήματα αυτά έχουν άμεση σχέση με την ασθένεια και θα βοηθήσουν στη γενετική χαρτογράφηση της ΗΕΩ

Adipose tissue development and the molecular regulation of lipid metabolism

The production of new adipocytes is required to maintain adipose tissue mass and involves the proliferation and differentiation of adipocyte precursor cells (APCs). In this review, we outline new developments in understanding the phenotype of APCs and provide evidence suggesting that APCs differ between distinct adipose tissue depots and are affected by obesity. Post-mitotic mature adipocytes regulate systemic lipid homeostasis by storing and releasing free fatty acids, and also modulate energy balance via the secretion of adipokines. The review highlights recent advances in understanding the cellular and molecular mechanisms regulating adipocyte metabolism, with a particular focus on lipolysis regulation and the involvement of microribonucleic acids (miRNAs)

Resolution of Macular Edema in Idiopathic Juxtafoveal Telangiectasis Using PDT

A 57-year-old woman was treated by, photodynamic therapy for macular edema due to idiopathic juxtafoveal telangiectasis (presumed type 1A) without subretinal neovascularization. Initial visual acuity of the treated eye was 20/200 and to 20/40 by 3 months after the photodynamic therapy Session. Visual acuity remained stable 32 months after the treatment. Color photographs and fundus fluorescein angiography before and after photodynamic therapy revealed regression of hemorrhages, exedates, and fluorescein leakage. Photodynamic therapy has long-term benefits for the patient with idiopathic juxtafoveal telangiectasis, presumed type 1A, because it can improve visual acuity and macular edema. [Ophthalmic Surg Lasers Imaging 2009;40:65-67.

Impact of endurance exercise training on adipocyte microRNA expression in overweight men

Adipocytes are major regulators of metabolism, and endurance exercise training improves adipocyte function; however, the molecular mechanisms that regulate chronic adaptive responses remain unresolved. microRNAs (miRNAs) influence adipocyte differentiation and metabolism. Accordingly, we aimed to determine whether adipocyte miRNA expression is responsive to exercise training and to identify exercise-responsive miRNAs that influence adipocyte metabolism. Next-generation sequencing was used to profile miRNA expression of adipocytes that were isolated from abdominal subcutaneous (ABD) and gluteofemoral (GF) adipose tissue of overweight men before and after 6 wk of endurance exercise training. Differentially expressed miRNAs were overexpressed or silenced in 3T3-L1 adipocytes, and lipid metabolism was examined. Next-generation sequencing identified 526 miRNAs in adipocytes, and there were no statistical differences in miRNA expression when comparing pre- and post-training samples for ABD and GF adipocytes. miR-10b expression was increased in ABD compared with GF adipocytes, whereas miR-204, miR-3613, and miR-4532 were more highly expressed in GF compared with ABD adipocytes. Blocking miR-10b in adipocytes suppressed β-adrenergic lipolysis but generally had a minor effect on lipid metabolism. Thus, unlike their critical role in adipogenesis, stable changes in miRNA expression do not play a prominent role in the regulation of adipocyte function in response to endurance exercise training.-Tsiloulis, T., Pike, J., Powell, D., Rossello, F. J., Canny, B. J., Meex, R. C. R., Watt, M. J. Impact of endurance exercise training on adipocyte microRNA expression in overweight men.Thomas Tsiloulis, Joshua Pike, David Powell, Fernando J. Rossello, Benedict J. Canny, Ruth C. R. Meex, Matthew J. Wat

No evidence of white adipocyte browning after endurance exercise training in obese men

Background/Objectives:The phenomenon of adipocyte ‘beiging’ involves the conversion of non-classic brown adipocytes to brown-like adipose tissue with thermogenic, fat-burning properties, and this phenomenon has been shown in rodents to slow the progression of obesity-associated metabolic diseases. Rodent studies consistently report adipocyte beiging after endurance exercise training, indicating that increased thermogenic capacity in these adipocytes may underpin the improved health benefits of exercise training. The aim of this study was to determine whether prolonged endurance exercise training induces beige adipogenesis in subcutaneous adipose tissues of obese men.Subjects/Methods:Molecular markers of beiging were examined in adipocytes obtained from abdominal subcutaneous (AbSC) and gluteofemoral (GF) subcutaneous adipose tissues before and after 6 weeks of endurance exercise training in obese men (n=6, 37.3±2.3 years, 30.1±2.3 kg m–2).Results:The mRNAs encoding the brown or beige adipocyte-selective proteins were very lowly expressed in AbSC and GF adipose tissues and exercise training did not alter the mRNA expression of UCP1, CD137, CITED, TBX1, LHX8 and TCF21. Using immunohistochemistry, neither multilocular adipocytes, nor UCP1 or CD137-positive adipocytes were detected in any sample. MicroRNAs known to regulate brown and/or beige adipose development were highly expressed in white adipocytes but endurance exercise training did not impact their expression.Conclusions:The present study reaffirms emerging data in humans demonstrating no evidence of white adipose tissue beiging in response to exercise training, and supports a growing body of work demonstrating divergence of brown/beige adipose location, molecular characterization and physiological function between rodents and humans

Genetic variants in complement pathway and ARMS2/HTRA1 genes and risk of age-related macular degeneration in a homogeneous population from central Greece

[No abstract available