Photoaged skin caused by chronic ultraviolet radiation (UVR) is characterised clinically with hyperpigmentation, coarse skin texture and deep wrinkles; the worst outcome is skin cancer. Histological investigation of the alteration within major extracellular matrices (ECM; elastic fibres, fibrillar collagens) is essential study to understand the cellular effect on skin structure from UVR. This thesis used an acute dose of radiation to examine in humans in vivo the effect of UVR on ECM components before assessing whether a dietary intervention could protect skin from UVR damage. Green tea catechins (GTCs) have anti-oxidant properties and may be an interesting option as a systemic photoprotection agent. Hence this thesis assesses: 1) the effect of acute irradiation of skin on dermal ECM damage to see whether it mimics the changes observed in photoageing and; 2) whether dietary supplementation with GTC will provide dermal ECM protection. UV-induced change in elastic fibre network. Initially, the effect of two different UV light sources on elastic fibre protein (elastic fibres, fibrillin-rich microfibrils and fibulin-2 and -5 microfibrils) remodelling was performed. The effect of ultraviolet B vs full-spectrum solar simulated radiation (SSR) were investigated in a small sample of healthy Caucasian volunteers (n = 6 per group). At 24 hour after 3× MED irradiation, Weigert's resorcin–fuchsin stained elastic fibres showed a significant reduction regardless of irradiation protocol (UVB, P<0.01; SSR P<0.05). Specific components were identified by immunohistochemistry; a significant reduction in fibrillin-rich microfibrils (FRM) was observed in UVB-irradiated skin (P<0.05), whilst fibulin-5-positive microfibrils were only affected by SSR (P<0.05). The data revealed, therefore, differential effects on UV wavelength on ECM remodelling. SSR, the more physiologically relevant light source was used in subsequent studies Supplement effect in SSR-induced damage in elastic fibre. Fifty healthy volunteers were recruited to this randomised control trial to investigate whether GTC can protect skin from photodamage. Volunteers were randomized to GTC (1080 mg plus 100 mg vitamin C; n=25) or placebo (maltodextrin; n = 25) daily for 12-weeks with compliance assessed biochemically in urine samples. Of the n = 50 recruited, 44 volunteers completed the study. In baseline, UVR challenge resulted in a significant remodeling of the cutaneous elastic fiber system (P<0.001), particularly fibulin-2 and fibulin-5-positive microfibrils at 24-hr after 3×MED irradiation. In post-supplementation, fibulin-5 positive microfibrils were protected from UVR remodeling (% staining, mean ± SE; no UV, 18.1±0.89; UVR, 17.1±0.61; P=0.30) whilst no protection was seen in the placebo group (no UVR, 19.41±0.79; UVR, 17.69±0.61; P<0.05). Supplement effect in SSR-induced damage in collagenous matrix. In the identical experiment, collagenous matrices including synthesis of procollagen I was also examined as fibrillar collagens are the major ECM components providing strength within dermis. The fibrillar collagen and newly synthesised procollagen I were stained by Picrosirius red and immunohistochemistry respectively. At baseline, acute irradiation significantly reduced papillary dermal fibrillar collagens (P<0.001) and induced deposition of newly synthesised pro-collagen I (P=0.02). In post-supplementation, GTC enhanced the deposition of thin collagen fibres in the dermis. Whilst placebo showed no effect on the altered organisation of fibrillar collagens or deposition of pro-collagen I following the irradiation challenge, GTC protected the organisation of fibrillar collagens in the papillary dermis (P=0.97).This novel in vivo human study may be used to recapitulate elastic fibre and collagen changes associated with photoageing and may be useful for dissecting out the mechanisms underlying extracellular matrix damage in response to chronic sunlight exposure. Furthermore, in a randomized control trial, dietary GTC protected fibulin-5 microfibrils and collagen fibres in the papillary dermis from UV-mediated degradation. The mechanism by which this protection occurs requires further study.

Die gesundheitsfördernden Eigenschaften von grünem Tee sind weitgehend akzeptiert. Den Teecatechinen, insbesondere dem Epigallocatechin-3-gallat (EGCG), werden zahlreiche positive Effekte zugesprochen (z. B. antioxidativ, antikanzerogen, antiinflammatorisch, Blutdruck und Cholesterinspiegel senkend). Die Mechanismen, die zu einer Reduktion der in Tierversuchen beschriebenen Körper- und Fettmasse führen, sind nicht ausreichend geklärt. Ziel dieser Arbeit bestand darin, die kurz- und mittelfristigen Wirkungen einer TEAVIGO®-Applikation (mind. 94 % EGCG) am Mausmodell im Hinblick auf den Energie- und Fettstoffwechsel sowie die Expression daran beteiligter Gene in wichtigen Organen und Geweben zu untersuchen. In verschiedenen Tierversuchen wurde männlichen C57BL/6-Mäusen eine Hochfettdiät (HFD) mit und ohne Supplementation (oral, diätetisch) des entkoffeinierten Grüntee-Extraktes TEAVIGO® in unterschiedlichen Dosierungen gefüttert. Es wurden sowohl kurz- als auch mittelfristige Wirkungen des EGCG auf die Energiebilanz (u. a. indirekte Tierkalorimetrie) und Körperzusammensetzung (NMR) sowie die exogene Substratoxidation (Stabilisotopentechnik: Atemtests, Inkorporation natürlicher 13C-angereicherter Triglyceride aus Maiskeimöl in diverse Organe/Gewebe) und Gen-expression (quantitative real-time PCR) untersucht. Die Applikationsform und ihre Dauer riefen unterschiedliche Wirkungen hervor. Mäuse mit diätetischer Supplementation zeigten bereits nach kurzer Zeit eine verminderte Körperfettmasse, die bei weiterer Verabreichung auch zu einer Reduktion der Körpermasse führte. Beide Applikationsformen resultieren, unabhängig von der Dauer der Intervention, in einer erhöhten Energieausscheidung, während die Futter- und Energieaufnahme durch EGCG nicht beeinflusst wurden. Der Energieverlust war von einer erhöhten Fett- und Stickstoffausscheidung begleitet, deren Ursache die in der Literatur beschriebene Interaktion und Hemmung digestiver Enzyme sein könnte. Besonders unter postprandialen Bedingungen wiesen EGCG-Mäuse erniedrigte Triglycerid- und Glycogengehalte in der Leber auf, was auf eine eingeschränkte intestinale Absorption der Nährstoffe hindeutet. Transkriptanalysen ergaben im Darm eine verminderte Expression von Fettsäuretransportern, während die Expression von Glucosetransportern durch EGCG erhöht wurde. Weiterhin reduzierte EGCG, nach Umstellung von Standard- auf eine maiskeimölhaltige Hochfettdiät, die Inkorporation natürlicher 13C-angereicherter Triglyceride in diverse Organe und Gewebe – insbesondere Leber, viszerales und braunes Fettgewebe sowie Skelettmuskel. Die Analyse der 13C-Anreicherung im Atem der Mäuse und die Energieumsatzmessungen ergaben nach kurzer Applikation eine erhöhte Fettoxidation, die im weiteren Verlauf der Intervention auf eine erhöhte Kohlenhydratoxidation umgeschaltet wurde. Weiterhin war die orale Applikation von EGCG bei gleichzeitiger Fütterung einer Hochfettdiät von makroskopischen und mikroskopischen degenerativen Veränderungen der Leber begleitet. Diese Effekte wurden nach diätetischer Supplementation der Hochfettdiät mit EGCG nicht beobachtet. Zusammenfassend zeigen die Ergebnisse, dass die Körpergewichts- und Fettgewebs-abnahme durch diätetisches EGCG sich durch eine herabgesetzte Verdaulichkeit der Nahrung erklären lässt. Dies führte zu verschiedenen kurz- und mittelfristigen Veränderungen in der Fettverteilung und im Fettmetabolismus. / The health-promoting properties of green tea are widely accepted. Tea catechins, particularly epigallocatechin-3-gallate (EGCG), are attributed to many positive effects (anti-oxidative, anti-cancerogen, anti-inflammatory, blood pressure and cholesterol lowering). Mechanisms leading to a reduction of body mass and fat mass in animal experiments are not fully elucidated. The aim of this study was to examine multiple effects of TEAVIGO® application (at least 94% EGCG) in a mouse model in terms of energy and fat metabolism. Expressions of genes involved in these processes were also determined in different organs and tissues. In several animal studies, male C57BL/6 mice were fed a high fat diet supplemented with decaffeinated TEAVIGO® (oral, dietetic) at different dosages. Short- and medium-term effects of EGCG were investigated on energy balance (indirect animal calorimetry), body composition (NMR), exogenous substrate oxidation (stable isotopes: breath tests, incorporation of naturally 13C-enriched triglycerides from corn oil into various organs/tissues), and gene expression (quantitative real-time PCR). Type of application and its duration elicited different effects. Supplemented mice already showed a reduced body fat mass after short- and medium-term treatment. Further administration lead to a reduction of body weight. Regardless of the duration of intervention, both types of application resulted in an increased energy excretion, while food and energy intake was not affected by EGCG. Fecal energy loss was accompanied by an increased fat and nitrogen excretion, which was probably due to an inhibition of digestive enzymes. Fed mice displayed a decreased triglyceride and glycogen content in liver suggesting a reduced absorption of nutrients in the intestine. This was supported by a decreased expression of intestinal fatty acid transporters. However, expression of glucose transporters was increased after short- and medium term application. Furthermore, EGCG attenuated incorporation of naturally 13C-enriched triglycerides into various organs and tissues – particularly liver, visceral and brown adipose tissue, and skeletal muscle. Analysis of 13C-enrichment in breath and measurement of energy expenditure revealed an initial increased fat oxidation, which was switched to an increased carbohydrate oxidation over time. Besides, a combination of oral administration of EGCG and high fat feeding was accompanied by macroscopic and microscopic deleterious changes in liver. These effects were not observed after dietary supplementation of EGCG. Altogether, reduction in body mass and fat mass by EGCG can be explained by a decreased food digestibility leading to various short- and medium-term changes in fat distribution and lipid metabolism.