Age-associated inflammation connects RAS-induced senescence to stem cell dysfunction and epidermal malignancy.

Aging is the single biggest risk factor for malignant transformation. Among the most common age-associated malignancies are non-melanoma skin cancers, comprising the most common types of human cancer. Here we show that mutant H-Ras activation in mouse epidermis, a frequent event in cutaneous squamous cell carcinoma (SCC), elicits a differential outcome in aged versus young mice. Whereas H-Ras activation in the young skin results in hyperplasia that is mainly accompanied by rapid hair growth, H-Ras activation in the aged skin results in more dysplasia and gradual progression to in situ SCC. Progression is associated with increased inflammation, pronounced accumulation of immune cells including T cells, macrophages and mast cells as well as excessive cell senescence. We found not only an age-dependent increase in expression of several pro-inflammatory mediators, but also activation of a strong anti-inflammatory response involving enhanced IL4/IL10 expression and immune skewing toward a Th2 response. In addition, we observed an age-dependent increase in the expression of Pdl1, encoding an immune suppressive ligand that promotes cancer immune evasion. Moreover, upon switching off oncogenic H-Ras activity, young but not aged skin regenerates successfully, suggesting a failure of the aged epidermal stem cells to repair damaged tissue. Our findings support an age-dependent link between accumulation of senescent cells, immune infiltration and cancer progression, which may contribute to the increased cancer risk associated with old age.

Granule exocytosis mediates immune surveillance of senescent cells.

Senescence is a stable cell cycle arrest program that contributes to tumor suppression, organismal aging and certain wound healing responses. During liver fibrosis, for example, hepatic stellate cells initially proliferate and secrete extracellular matrix components that produce fibrosis; however, these cells eventually senesce and are cleared by immune cells, including natural killer (NK) cells. Here, we examine how NK cells target senescent cells and assess the impact of this process on liver fibrosis. We show that granule exocytosis, but not death-receptor-mediated apoptosis, is required for NK-cell-mediated killing of senescent cells. This pathway bias is due to upregulation of the decoy death receptor, Dcr2, an established senescence marker that attenuates NK-mediated cell death. Accordingly, mice with defects in granule exocytosis accumulate senescent stellate cells and display more liver fibrosis in response to a fibrogenic agent. Our results thus provide new insights into the immune surveillance of senescent cells and reveal how granule exocytosis has a protective role against liver fibrosis.

CCL2 (pM levels) as a therapeutic agent in Inflammatory Bowel Disease models in mice.

BACKGROUND: Chemokines regulate the pathways that restrict homing of specific subsets of immune cells, and thereby fine tune the immune response at specific lymphoid and peripheral tissues. CCL2 is a chemokine that induces migration of monocytes, memory T cells, and dendritic cells. Previously, we demonstrated that pM levels of CCL2 dramatically inhibit migration of T cells. The aim was to test whether subphysiological doses of CCL2 can ameliorate murine colitis and inflammation-induced colorectal cancer. METHODS: TNBS (2,4,6 trinitrobenzene sulfonic acid) colitis and dextran sodium sulfate (DSS) colitis were induced in Balb/c and C57BL/6 mice, respectively. Mice were treated daily with intraperitoneal CCL2 injections. Disease activity was assessed clinically, histologically, and by measuring inflammatory cytokine levels. In addition, an inflammatory cancer model was induced by azoxymethane-DSS (AOM-DSS) in Balb/c mice. Mice were treated daily with CCL2 for 11 weeks and then assessed for number of tumors in the colons. RESULTS: Daily administration of CCL2 (60-120 ng) significantly decreased the development of TNBS- and DSS-induced colitis. In a DSS-AOM model, CCL2-treated mice developed significantly fewer tumors (P < 0.005) at 11 weeks. Chronic inflammation in the CCL2-treated mice was significantly less pronounced as compared to phosphate-buffered saline-treated mice. CONCLUSIONS: Administration of pM levels of CCL2 significantly inhibits migration of T cells in amelioration of TNBS and DSS colitis and inhibits development of colorectal cancer in an AOM-DSS colitis model in mice. Thus, pM levels of CCL2 may be clinically beneficial as an antiinflammatory agent in IBD.

The efficiency of humectants as skin moisturizers in the presence of oil.

BACKGROUND/AIMS: The research on the treatment of "dry skin syndrome" is hampered by the lack of a suitable animal model. Formerly, we developed a validated guinea pig in vivo model in which the dry skin syndrome persists at least for 1 week. We can, therefore, compare the pharmacological effectiveness of known and potential moisturizers for the treatment of dry skin syndrome. Our aim is to study whether the moisturizing efficiency of humectants depends on the solvents in which they are dissolved. METHODS: "Dry skin syndrome" was induced on the shaved skin on one side of guinea pigs by daily application of 2% sodium lauryl sulphate in deionized water (SLS) for 3 days. The other shaved side was used as control. After ascertaining skin dryness, that side was treated for 6 days with glycerol or 1,2-hexanediol in different solvents: water, or medium chain triglycerides (MCT) or mixtures of MCT with isopropyl alcohol in different proportions. Measurement of the in vivo moisturizing effect was carried out by a Comeometer CM 825; erythema was measured by a Mexameter MX 16. RESULTS: Treatments with glycerol (1M) in water reversed the skin dryness shown by both instruments. When dissolving glycerol in MCT, no moisturizing effect was found, probably because glycerol does not dissolve in the oil. No moisturizing effect was found with different combinations of glycerol in the mixtures of MCT and isopropyl alcohol. No moisturizing effect was found using another polyol moisturizer: 1,2 hexanediol (1M) dissolved in MCT oil. Glycerol or 1,2-hexanediol abolished the erythema only when they were dissolved in water alone. CONCLUSION: Polyol moisturizers such as glycerol or 1,2-hexanediol do not act in the presence of oils against the sodium lauryl sulphate-induced dry skin in our guinea pig model. Since in an oil-in-water (O/W) emulsion, the water evaporates within several minutes, one has to question the ability of moisturizing emulsions to treat dry skin. In such instances, one cannot draw conclusions about the moisturizing efficiency of the preparation merely from the presence of the humectant. One has to study the effect of the finished preparation.

Studies on the Diffusion of Molecules through Pores in Monolayer and Multilayer Films.

A one-parameter model for species flux through pores in a crystalline monolayer or multilayer film is developed. The model is based on surface diffusion of the species on the upstream surface of the monolayer and one-directional diffusion of the species into the pores of the monolayer. It is found that the Fickian diffusivity depends on the concentration of adsorbed species on surface sites and on the pore coverage. The model contains an important parameter, the rate constant of activation, which is function of the diffusing species and film surface properties. The model is compared with experimental data on ion and gas flux through single and multilayer films. Good agreement between theory and experiment is found with all sets of the data with the rate constant as a sole adjustable parameter. Copyright 1998 Academic Press.

Effects of chronic overload training and aging on left ventricular systolic function.

To examine the effects of age and chronic overload training on left ventricular systolic function during static exercise, Doppler echocardiography studies were performed in 14 young (28 +/- 6 years) and 10 older (51 +/- 3 years) weight lifters and also in 14 young (29 +/- 6 years) and 10 older (52 +/- 1.1 years) normal individuals during upright dead-lift isometric exercise, at 30% of maximal voluntary contraction for 3 min. At rest, older weight lifters demonstrated impaired left ventricular systolic function as compared with the other three groups. During exercise, peak and mean velocity values increased significantly (p < 0.05) from resting values in the young groups, but remained unchanged in the older groups. Flow period and acceleration and deceleration times were significantly (p < 0.05) lower in the younger subjects than those observed for the old ones, with the highest (p < 0.05) values obtained by the old weight lifters. This study suggests that the differences between the groups are related to differences in impedance and not to fundamental changes in the properties of the myocardium.

Influence of the time of day on physical performance in patients with coronary artery disease.

The exercise training workload for cardiac patients is determined from the peak heart rate achieved safely during a stress test. Circadian rhythms may play a key role in changing physiological responses to the stress test. Therefore, the purpose of this study was to evaluate the influence of the time of day on cardiopulmonary and metabolic responses in highly trained men with coronary artery disease. A group of 15 patients with coronary artery disease [53.5 (SD 6) years] performed two sessions of graded tests to exhaustion: one session was performed at 10 a.m. and the second at 5 p.m. in randomized order. Treadmill velocity was kept constant at a speed of 4.8 km h-1 starting with an elevation of 0% which was increased thereafter by 2.5% every 3 min. At rest the results revealed that only oxygen uptake was significantly lower (P < 0.05) in the morning compared to that observed in the evening [2.9 (SD 0.4) compared to 3.5 (SD 0.5) ml O2.kg-1.min-1, respectively]. During exercise, differences due to time of day were found in the variables of maximal oxygen uptake which were significantly higher (P < 0.05) in the evening than in the morning [34.2 (SD 2.6) and 40.8 (SD 2.5) ml O2.kg-1.min-1, respectively]. These data indicated that in these well-trained coronary artery disease patients there was a significant time of day effect associated with metabolic responses following stress-testing.

Left ventricular responses during prolonged treadmill walking with heavy load carriage.

This study examined with metabolic cart and echo-Doppler the influence of different load carriage during 4 h of treadmill walking on left ventricular systolic function, hemodynamics, and cardiovascular responses. Twenty-six aerobically well-trained male subjects (VO2max = 65.2 +/- 5 ml.kg-1.min-1) volunteered for this study. Subjects carried a load of 38 kg during one session and a load of 50 kg during the other session. Following the 4-h exercise in each session, significant (P < 0.05) differences were noted between the 38-kg and 50-kg workloads with regard to VO2: 14.4 +/- 2 and 19 +/- 5 ml.kg-1.min-1; heart rate: 104 +/- 14 and 125 +/- 17 beats.min-1; diastolic blood pressure: 69 +/- 4 and 79 +/- 4 mm Hg; and rate pressure product 140.4 +/- 15 and 173.8 +/- 20 index.10(-2), respectively. No significant differences were noted between the workloads in regard to systolic blood pressure, perceived exertion rating, and aortic valve Doppler indices. We concluded that during prolonged treadmill walking in well-trained young subjects, the additional load above 50% up to 66% of body weight did not change the steady state of left ventricular systolic function, hemodynamics, and cardiovascular responses throughout the course of the 240 min of effort.