Oral caffeine during voluntary exercise markedly inhibits skin carcinogenesis and decreases inflammatory cytokines in UVB-treated mice

Plant Secondary Metabolites against Skin Photodamage: Mexican Plants, a Potential Source of UV-Radiation Protectant Molecules

Human skin works as a barrier against the adverse effects of environmental agents, including ultraviolet radiation (UVR). Exposure to UVR is associated with a variety of harmful effects on the skin, and it is one of the most common health concerns. Solar UVR constitutes the major etiological factor in the development of cutaneous malignancy. However, more than 90% of skin cancer cases could be avoided with appropriate preventive measures such as regular sunscreen use. Plants, constantly irradiated by sunlight, are able to synthesize specialized molecules to fight against UVR damage. Phenolic compounds, alkaloids and carotenoids constitute the major plant secondary metabolism compounds with relevant UVR protection activities. Hence, plants are an important source of molecules used to avoid UVR damage, reduce photoaging and prevent skin cancers and related illnesses. Due to its significance, we reviewed the main plant secondary metabolites related to UVR protection and its reported mechanisms. In addition, we summarized the research in Mexican plants related to UV protection. We presented the most studied Mexican plants and the photoprotective molecules found in them. Additionally, we analyzed the studies conducted to elucidate the mechanism of photoprotection of those molecules and their potential use as ingredients in sunscreen formulas.

Caffeine stimulates voluntary wheel running in mice without increasing aerobic capacity

The "energy drink" Red Bull and the "sports drink" Gatorade are often marketed to athletes, with claims that they cause performance gains. However, both are high in sugars, and also consumed by non-athletes. Few studies have addressed the effects of these drinks or their biologically active components in rodent exercise models. We used three experiments to test effects on both voluntary exercise behavior and maximal aerobic capacity in lines of mice known to differ in "athletic" traits. Mice from four replicate High Runner (HR) lines have been selectively bred for voluntary running on wheels, and run approximately three times as many revolutions per day as do mice from four non-selected Control (C) lines. HR mice also have higher endurance and maximal oxygen consumption (VO₂max) during forced treadmill exercise. In Experiment 1, we tested the hypothesis that Gatorade or Red Bull might cause or allow mice to increase their voluntary wheel running. On days 5 and 6 of 6days of wheel access, as is used to select breeders, HR mice ran 3.3-fold more than C, and females ran 1.2-fold more than males, with no linetype by sex interaction. On day 7, mice were administered Gatorade, Red Bull or tap water. During the subsequent 19-hour period, Gatorade had no statistical effect on running, but Red Bull significantly increased distance run by both sexes and in both HR and C lines. The increase in distance run caused by Red Bull was attributable to time spent running, not an increase in mean (or maximum) speed. As previous studies have found that sucrose alone does not generally increase wheel running, we tested two other active ingredients in Red Bull, caffeine and taurine, in Experiment 2. With a similar testing protocol, caffeine alone and caffeine+taurine increased running by about half the magnitude of Red Bull. In Experiment 3, we tested the hypothesis that Red Bull or caffeine alone can increase physiological performance ability during aerobic exercise, measured as VO₂max. In a repeated-measures design spanning 6days, females were housed with water bottles containing Red Bull, caffeine or water in a randomized order, and tested for VO₂max twice while receiving each fluid (6 total trials). Neither Red Bull nor caffeine significantly affected either VO₂max or a measure of trial cooperativity (rated on a scale of 1-5), but both treatments significantly reduced tiredness (rated on a scale of 1-3) scored at the end of trials for both HR and C lines. Taken together, our results suggest that caffeine increases voluntary exercise levels of mice by delaying fatigue, rather than increasing aerobic capacity.

Pseudomonas aeruginosa infection augments inflammation through miR-301b repression of c-Myb-mediated immune activation and infiltration

microRNAs (miRNAs) play critical roles in various biological processes including cell proliferation, development, and host defense. However, the molecular mechanism for miRNAs in regulating bacterial-induced inflammation remains largely unclear. Here we report that miR-301b augments pro-inflammatory response during pulmonary infection and caffeine (CAF) suppresses miR-301b’s effect and thereby augmenting respiratory immunity. LPS treatment or Pseudomonas aeruginosa infection induces miR-301b expression via a TLR4/MyD88/NF-κB pathway. Importantly, CAF decreases miR-301b expression through negative regulation of the cAMP/PKA/NF-κB axis. Further, c-Myb is identified as a target of miR-301b, which positively modulates anti-inflammatory cytokines IL-4 and TGF-β1, but negatively regulates pro-inflammatory cytokines MIP-1α and IL-17A. Moreover, repression of miR-301b results in increased transcription of c-Myb and elevated levels of neutrophil infiltration, thereby alleviating infectiou symptoms in mice. These findings reveal miR-301b as a new controller of inflammatory response by repressing c-Myb function to inhibit anti-inflammatory response to bacterial infection, representing a novel mechanism for balancing inflammation.

Coffee consumption and the risk of malignant melanoma in the Norwegian Women and Cancer (NOWAC) Study

Background

Coffee contains biologically-active substances that suppress carcinogenesis in vivo, and coffee consumption has been associated with a lower risk of malignant melanoma. We studied the impact of total coffee consumption and of different brewing methods on the incidence of malignant melanoma in a prospective cohort of Norwegian women.

Methods

We had baseline information on total coffee consumption and consumption of filtered, instant, and boiled coffee from self-administered questionnaires for 104,080 women in the Norwegian Women and Cancer (NOWAC) Study. We also had follow-up information collected 6–8 years after baseline. Multiple imputation was used to deal with missing data, and multivariable Cox regression models were used to calculate hazard ratios (HR) for malignant melanoma by consumption category of total, filtered, instant, and boiled coffee.

Results

During 1.7 million person-years of follow-up, 762 cases of malignant melanoma were diagnosed. Compared to light consumers of filtered coffee (≤1 cup/day), we found a statistically significant inverse association with low-moderate consumption (>1–3 cups/day, HR = 0.80; 95 % confidence interval [CI] 0.66–0.98) and high-moderate consumption of filtered coffee (>3–5 cups/day, HR = 0.77; 95 % CI 0.61–0.97) and melanoma risk (p_trend = 0.02). We did not find a statistically significant association between total, instant, or boiled coffee consumption and the risk of malignant melanoma in any of the consumption categories.

Conclusions

The data from the NOWAC Study indicate that a moderate intake of filtered coffee could reduce the risk of malignant melanoma.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2586-5) contains supplementary material, which is available to authorized users.

Caffeine Mitigates Lung Inflammation Induced by Ischemia-Reperfusion of Lower Limbs in Rats

Reperfusion of ischemic limbs can induce inflammation and subsequently cause acute lung injury. Caffeine, a widely used psychostimulant, possesses potent anti-inflammatory capacity. We elucidated whether caffeine can mitigate lung inflammation caused by ischemia-reperfusion (IR) of the lower limbs. Adult male Sprague-Dawley rats were randomly allocated to receive IR, IR plus caffeine (IR + Caf group), sham-operation (Sham), or sham plus caffeine (n = 12 in each group). To induce IR, lower limbs were bilaterally tied by rubber bands high around each thigh for 3 hours followed by reperfusion for 3 hours. Caffeine (50 mg/kg, intraperitoneal injection) was administered immediately after reperfusion. Our histological assay data revealed characteristics of severe lung inflammation in the IR group and mild to moderate characteristic of lung inflammation in the IR + Caf group. Total cells number and protein concentration in bronchoalveolar lavage fluid of the IR group were significantly higher than those of the IR + Caf group (P < 0.001 and P = 0.008, resp.). Similarly, pulmonary concentrations of inflammatory mediators (tumor necrosis factor-α, interleukin-1β, and macrophage inflammatory protein-2) and pulmonary myeloperoxidase activity of the IR group were significantly higher than those of the IR + Caf group (all P < 0.05). These data clearly demonstrate that caffeine could mitigate lung inflammation induced by ischemia-reperfusion of the lower limbs.

Mechanisms of Photoaging and Cutaneous Photocarcinogenesis, and Photoprotective Strategies with Phytochemicals

Photoaging and photocarcinogenesis are primarily due to solar ultraviolet (UV) radiation, which alters DNA, cellular antioxidant balance, signal transduction pathways, immunology, and the extracellular matrix (ECM). The DNA alterations include UV radiation induced thymine-thymine dimers and loss of tumor suppressor gene p53. UV radiation reduces cellular antioxidant status by generating reactive oxygen species (ROS), and the resultant oxidative stress alters signal transduction pathways such as the mitogen-activated protein kinase (MAPK), the nuclear factor-kappa beta (NF-κB)/p65, the janus kinase (JAK), signal transduction and activation of transcription (STAT) and the nuclear factor erythroid 2-related factor 2 (Nrf2). UV radiation induces pro-inflammatory genes and causes immunosuppression by depleting the number and activity of the epidermal Langerhans cells. Further, UV radiation remodels the ECM by increasing matrixmetalloproteinases (MMP) and reducing structural collagen and elastin. The photoprotective strategies to prevent/treat photoaging and photocarcinogenesis include oral or topical agents that act as sunscreens or counteract the effects of UV radiation on DNA, cellular antioxidant balance, signal transduction pathways, immunology and the ECM. Many of these agents are phytochemical derivatives and include polyphenols and non-polyphenols. The flavonoids are polyphenols and include catechins, isoflavones, proanthocyanidins, and anthocyanins, whereas the non-flavonoids comprise mono phenolic acids and stilbenes. The natural sources of polyphenols include tea, cocoa, grape/wine, soy, pomegranate, and Polypodium leucotomos. The non-phenolic phytochemicals include carotenoids, caffeine and sulphoraphance (SFN). In addition, there are other phytochemical derivatives or whole extracts such as baicalin, flavangenol, raspberry extract, and Photomorphe umbellata with photoprotective activity against UVB radiation, and thereby carcinogenesis.

Caffeine intake may modulate inflammation markers in trained rats

Caffeine is presented in many commercial products and has been proven to induce ergogenic effects in exercise, mainly related to redox status homeostasis, inflammation and oxidative stress-related adaptation mechanisms. However, most studies have mainly focused on muscle adaptations, and the role of caffeine in different tissues during exercise training has not been fully described. The aim of this study was therefore, to analyze the effects of chronic caffeine intake and exercise training on liver mitochondria functioning and plasma inflammation markers. Rats were divided into control, control/caffeine, exercise, and exercise/caffeine groups. Exercise groups underwent four weeks of swimming training and caffeine groups were supplemented with 6 mg/kg/day. Liver mitochondrial swelling and complex I activity, and plasma myeloperoxidase (MPO) and acetylcholinesterase (AChE) activities were measured. An anti-inflammatory effect of exercise was evidenced by reduced plasma MPO activity. Additionally, caffeine intake alone and combined with exercise decreased the plasma AChE and MPO activities. The per se anti-inflammatory effect of caffeine intake should be highlighted considering its widespread use as an ergogenic aid. Therefore, caffeine seems to interfere on exercise-induced adaptations and could also be used in different exercise-related health treatments.