mTOR inhibition by rapamycin increases ceramide synthesis by promoting transforming growth factor-β1/Smad signaling in the skin

Although mammalian target of rapamycin (mTOR) mediates a wide variety of biological functions, little information is available on the effect of mTOR on the functions of skin cells. In this study, we investigated effects of mTOR inhibition by rapamycin on ceramide synthesis in the skin of rats and human keratinocytes and its regulatory mechanisms. The phosphorylation of p70 S6 kinase, which indicates mTOR activation, was induced in the skin of rats fed a high-fat diet, but this abnormality was reversed by supplementation with rapamycin. Ceramide levels and the mRNA levels of serine palmitoyltransferase (SPT) and transforming growth factor (TGF)-β1 were suppressed in the skin of rats fed high-fat diets, but this abnormality was reversed by supplementation with rapamycin. TGF-β1-induced SPT mRNA expression was blocked by SB525334, an inhibitor of TGF-β1-induced Smad2/3 nuclear localization, in human keratinocytes. Rapamycin-induced SPT mRNA expression was blocked by an anti-TGF-β1 antibody or SB525334 in human keratinocytes. These results show that mTOR inhibition by rapamycin increases ceramide synthesis by promoting TGF-β1/Smad signaling in the skin.

N-methyl-d-aspartate receptor coagonist d-serine suppresses intake of high-preference food

d-Serine is abundant in the forebrain and physiologically important for modulating excitatory glutamatergic neurotransmission as a coagonist of synaptic N-methyl-d-aspartate (NMDA) receptor. NMDA signaling has been implicated in the control of food intake. However, the role of d-serine on appetite regulation is unknown. To clarify the effects of d-serine on appetite, we investigated the effect of oral d-serine ingestion on food intake in three different feeding paradigms (one-food access, two-food choice, and refeeding after 24-h fasting) using three different strains of male mice (C57Bl/6J, BKS, and ICR). The effect of d-serine was also tested in leptin signaling-deficient db/db mice and sensory-deafferented (capsaicin-treated) mice. The expression of orexigenic neuropeptides [neuropeptide Y (Npy) and agouti-related protein (Agrp)] in the hypothalamus was compared in fast/refed experiments. Conditioned taste aversion for high-fat diet (HFD) was tested in the d-serine-treated mice. Under the one-food-access paradigm, some of the d-serine-treated mice showed starvation, but not when fed normal chow. HFD feeding with d-serine ingestion did not cause aversion. Under the two-food-choice paradigm, d-serine suppressed the intake of high-preference food but not normal chow. d-Serine also effectively suppressed HFD intake but not normal chow in db/db mice and sensory-deafferented mice. In addition, d-serine suppressed normal chow intake after 24-h fasting despite higher orexigenic gene expression in the hypothalamus. d-Serine failed to suppress HFD intake in the presence of L-701,324, the selective and full antagonist at the glycine-binding site of the NMDA receptor. Therefore, d-serine suppresses the intake of high-preference food through coagonism toward NMDA receptors.

Calcitonin gene-related peptide regulates mitogen-activated protein kinase pathway to decrease transforming growth factor β1-induced hepatic plasminogen activator inhibitor-1 mRNA expression in HepG2 cells

Transforming growth factor (TGF) β1-induced plasminogen activator inhibitor (PAI)-1 is one of factors associated with the development of hepatic fibrosis. Calcitonin gene-related peptide (CGRP) shows hepatoprotective effect during hepatic injuries, including fibrosis. However, the effects of CGRP on PAI-1 expression induced by TGFβ1 are unknown. In this study, we investigated the effect of CGRP on TGFβ1-induced PAI-1 expression and its regulatory mechanisms in HepG2 cells. CGRP inhibited TGFβ1-induced PAI-1 expression. H89, a protein kinase A inhibitor, abolished the inhibition of TGFβ1-induced PAI-1 expression by CGRP. TGFβ1 activated mitogen-activated protein kinase (MAPK), including extracellular signal-regulated kinase, c-jun NH2-terminal kinase, and p38, and this activation was abolished by CGRP. These results show that the CGRP-induced cAMP/PKA activation suppresses activation of MAPK induced by TGFβ1, leading to decreased PAI-1 expression in HepG2 cells.

Three-year denosumab treatment in postmenopausal Japanese women and men with osteoporosis: results from a 1-year open-label extension of the Denosumab Fracture Intervention Randomized Placebo Controlled Trial (DIRECT)

SUMMARY

A 12-month extension phase of DIRECT in Japanese subjects with osteoporosis showed that total 3 years of denosumab treatment in Japanese postmenopausal women and men with osteoporosis was associated with low fracture rates, persistent bone turnover marker (BTM) reductions, continuous bone mineral density (BMD) increases, and a favorable overall benefit/risk profile.

INTRODUCTION

The DIRECT trial demonstrated that 2 years of treatment with denosumab 60 mg subcutaneously every 6 months significantly reduced the incidence of vertebral fracture compared to placebo in Japanese postmenopausal women and men with osteoporosis. The purpose of this study is to evaluate the efficacy and safety of denosumab treatment for up to 3 years.

METHODS

This study includes a 2-year randomized, double-blind, placebo-controlled phase and a 1-year open-label extension phase in which all subjects received denosumab. The data correspond to 3 years of denosumab treatment in subjects who received denosumab (long-term group) and 1 year of denosumab treatment in subjects who received placebo (cross-over group) in the double-blind phase.

RESULTS

Eight hundred and ten subjects who completed the double-blind phase enrolled into the extension phase, and 775 subjects completed the study. All subjects received denosumab with daily supplements of calcium and vitamin D. The cumulative 36-month incidences of new or worsening vertebral fractures and new vertebral fractures were 3.8 and 2.5 %, respectively, in the long-term group. In this group, the BMD continued to increase, and the reduction in BTMs was maintained. In the cross-over group, comparable BMD increases and BTMs reductions to those of in their first year of the long-term group were confirmed. Adverse events did not show a notable increase with long-term denosumab administration. One event of osteonecrosis of the jaw occurred in the cross-over group.

CONCLUSIONS

Three-year denosumab treatment in Japanese subjects with osteoporosis showed a favorable benefit/risk profile.

Overexpression of insulin receptor partially improves obese and diabetic phenotypes in db/db mice

Type 2 diabetes mellitus (T2DM) is one of the major health concern among the world. Several treatment options for T2DM are in clinical use, including injecting insulin, promoting insulin secretion by insulin secretagogues, and improving insulin sensitivity by insulin sensitizers. However, increasing the amount of insulin receptor in insulin-target tissues has not been explored. In order to test the efficacy of insulin receptor overexpression for improving glucose control, we established a transgenic mouse line expressing human insulin receptor (INSR). We analyzed, growth, energy balance, and glucose control of INSR-overexpressing db/db mice (INSR; db/db), which we produced by mating INSR transgenic mice with db/db mice, a genetic model of obesity due to insufficient leptin signaling. Compared to db/db mice, INSR; db/db mice were rescued from hyperphagia and obesity, leading to improved blood glucose levels. Unexpectedly, however, INSR; db/db mice presented with stunted growth, accompanied by decreased plasma levels of free IGF1 and IGFBP-3, indicating the down-regulation of GH/IGF1 axis. These phenotypes were observed in INSR; db/db mice but not in INSR littermates. Meanwhile, bone defects observed in db/db male mice were not rescued. Moreover, improved blood glucose was not accompanied by improved insulin sensitivity. Therefore, overexpression of insulin receptor improves obese and diabetic phenotypes in db/db mice, with consequences on growth.

Arterial stiffness is increased in young women with endometriosis

Endometriosis is a chronic gynaecological disorder that is accompanied by inflammation and oxidative stress. Atherosclerosis has a long subclinical progression in arteries of children and young adults decades before overt clinical manifestations of the disease. In this study, we determined arterial stiffness by measuring brachial-ankle pulse wave velocity (baPWV) in women with endometriosis to assess the presence of subclinical atherosclerosis. We also measured markers of inflammation and oxidative stress in women with endometriosis. baPWV in women with endometriosis aged over 30 years was significantly higher than that in women without endometriosis aged over 30 years (p < 0.05), but not in women aged less than 30. Serum high-sensitivity C-reactive protein level in women with endometriosis was significantly higher than that in controls (p < 0.05). Young women with endometriosis show significantly increased arterial stiffness, suggesting that women with endometriosis need to be cautious of the future onset of atherosclerosis.

Sirt1 rescues the obesity induced by insulin-resistant constitutively-nuclear FoxO1 in POMC neurons of male mice

OBJECTIVE

The hypothalamus is the brain center that controls the energy balance. Anorexigenic proopiomelanocortin (POMC) neurons and orexigenic AgRP neurons in the arcuate nucleus of the hypothalamus plays critical roles in energy balance regulation. FoxO1 is a transcription factor regulated by insulin signaling that is deacetylated by Sirt1, a nicotinamide adenine dinucleotide- (NAD(+) -) dependent deacetylase. Overexpression of insulin-resistant constitutively-nuclear FoxO1 (CN-FoxO1) in POMC neurons leads to obesity, whereas Sirt1 overexpression in POMC neurons leads to leanness. Whether overexpression of Sirt1 in POMC neurons could rescue the obesity caused by insulin-resistant CN-FoxO1 was tested here.

METHODS

POMC neuron-specific CN-FoxO1/Sirt1 double-KI (DKI) mice were analyzed.

RESULTS

The obese phenotype of CN-FoxO1 KI mice was rescued in male DKI mice. Reduced O2 consumption, increased adiposity, and fewer POMC neurons observed in CN-FoxO1 mice were rescued in male DKI mice without affecting food intake and locomotor activity. Sirt1 overexpression decreased FoxO1 acetylation and protein levels without affecting its nuclear localization in mouse embryonic fibroblasts and hypothalamic N41 cells.

CONCLUSIONS

Sirt1 rescues the obesity induced by insulin-resistant CN-FoxO1 in POMC neurons of male mice by decreasing FoxO1 protein through deacetylation. Sirt1 ameliorates obesity caused by a genetic model of central insulin resistance.

Ultraviolet B irradiation reduces the expression of adiponectin in ovarial adipose tissues through endocrine actions of calcitonin gene-related peptide-induced serum amyloid A

Ultraviolet (UV) B irradiation decreases blood adiponectin levels, but the mechanism is not well understood. This study investigated how UVB irradiation reduces adiponectin expression in ovarial adipose tissues. Female Hos:HR-1 hairless mice were exposed to UVB (1.6 J/cm²) irradiation and were killed 24 h later. UVB irradiation decreased the adiponectin protein level in the serum and the adiponectin mRNA level in ovarial adipose tissues. UVB irradiation also decreased the mRNA levels of peroxisome proliferator-activated receptor (PPAR) γ, CCAAT/enhancer binding protein (C/EBP) α, C/EBPβ, and fatty acid binding protein 4 (aP2) in ovarial adipose tissues. In contrast, UVB irradiation increased the mRNA levels of interleukin (IL)-6 and monocyte chemoattractant protein (MCP)-1 in ovarial adipose tissues. In the serum and liver, the levels of serum amyloid A (SAA), involved in PPARγ, C/EBPα, C/EBPβ, aP2, IL-6, and MCP-1 regulation, increased after UVB irradiation. The SAA gene is regulated by IL-1β, IL-6, and tumor necrosis factor-α, but only IL-6 expression increased in the liver after UVB irradiation. Additionally, in the liver, hypothalamus, and epidermis, UVB irradiation increased the expression of calcitonin gene-related peptide (CGRP), which upregulates SAA in the liver. Collectively, our results suggest that the CGRP signal induced by skin exposure to UVB transfers to the liver, possibly through the brain, and increases SAA production via IL-6 in the liver. In turn, serum SAA acts in an endocrine manner to decreases the serum adiponectin level by downregulating factors that regulate adiponectin expression in adipose tissues.

Difference in the ratio of high-molecular weight (HMW) to total adiponectin and HMW adiponectin in late post-menopausal women

OBJECTIVE

High-molecular weight (HMW) isoform level and HMW ratio have been shown to be better predictors of insulin sensitivity and metabolic syndrome than total adiponectin level.We examined the changes in circulating levels of HMW adiponectin and ratios of HMW to total adiponectin in women during the menopausal transition.

METHODS

We conducted a cross-sectional study in 217 healthy women and divided them into 4 stages: 58 women in pre-menopausal, 69 women in perimenopausal, 62 women in early post-menopausal and 28 women in late post-menopausal phase. Serum levels of total adiponectin and HMW adiponectin were measured by an enzyme-linked immunosorbent assay.

RESULTS

In late post-menopausal women, HMW adiponectin level was significantly higher than that in peri-menopausal women and the HMW to total adiponectin ratio was significantly lower than that in early post-menopausal women. In peri-menopausal women, HMW adiponectin level was significantly lower than that in pre-menopausal women and HMW to total adiponectin ratio was significantly lower than the ratios in pre-menopausal and early post-menopausal women.

CONCLUSION

The ratio of HMW to total adiponectin is low in late post-menopausal women, though both levels of total and HMW adiponectin were high after menopause in our cross-sectional study.

Hydrocellular foam dressing promotes wound healing along with increases in hyaluronan synthase 3 and PPARα gene expression in epidermis

BACKGROUND

Hydrocellular foam dressing, modern wound dressing, induces moist wound environment and promotes wound healing: however, the regulatory mechanisms responsible for these effects are poorly understood. This study was aimed to reveal the effect of hydrocellular foam dressing on hyaluronan, which has been shown to have positive effects on wound healing, and examined its regulatory mechanisms in rat skin.

METHODOLOGY/PRINCIPAL FINDINGS

We created two full-thickness wounds on the dorsolateral skin of rats. Each wound was covered with either a hydrocellular foam dressing or a film dressing and hyaluronan levels in the periwound skin was measured. We also investigated the mechanism by which the hydrocellular foam dressing regulates hyaluronan production by measuring the gene expression of hyaluronan synthase 3 (Has3), peroxisome proliferator-activated receptor α (PPARα), and CD44. Hydrocellular foam dressing promoted wound healing and upregulated hyaluronan synthesis, along with an increase in the mRNA levels of Has3, which plays a primary role in hyaluronan synthesis in epidermis. In addition, hydrocellular foam dressing enhanced the mRNA levels of PPARα, which upregulates Has3 gene expression, and the major hyaluronan receptor CD44.

CONCLUSIONS/SIGNIFICANCE

These findings suggests that hydrocellular foam dressing may be beneficial for wound healing along with increases in hyaluronan synthase 3 and PPARα gene expression in epidermis. We believe that the present study would contribute to the elucidation of the mechanisms underlying the effects of hydrocellular foam dressing-induced moist environment on wound healing and practice evidence-based wound care.

Increased frequency of skin-infiltrating FoxP3+ regulatory T cells as a diagnostic indicator of severe atopic dermatitis from cutaneous T cell lymphoma

Differential diagnosis of cutaneous T cell lymphoma (CTCL) and severe atopic dermatitis (AD) is often difficult because of the similarity in their skin manifestations. However, such differentiation is extremely important because of the differences in remedy and prognosis. The aim of this study was to investigate new, helpful diagnostic aids for distinguishing CTCL from AD. The frequency of forkhead box protein 3(+) (FoxP3(+)) regulatory T cells (T(regs)) in cutaneous lesions was evaluated among the three populations. Serum-soluble interleukin-2 receptor (sIL-2R), immunoglobulin (Ig)E-radioimmunosorbent test, lactate dehydrogenase (LDH) and blood eosinophil count were measured in 11 CTCL patients (including three CTCL patients misdiagnosed previously with intractable AD), 10 adult AD patients and nine psoriasis patients. The frequency of T(regs) was increased significantly in cutaneous lesions of AD compared with those of CTCL. Serum IgE and LDH levels were also elevated significantly in AD compared with CTCL, whereas there were no significant differences in serum sIL-2R levels between CTCL and AD. In the three CTCL patients who were misdiagnosed with intractable AD, IgE and LDH levels were lower than in AD patients, whereas serum sIL-2R levels were as high as in AD patients and higher than in the other eight CTCL patients. The higher frequency of T(regs) in the cutaneous lesions of patients with AD than in those with CTCL and higher serum IgE and LDH levels in patients with AD than in those with CTCL might be helpful reference values for the differential diagnosis of these two diseases.

P53 expression in esophageal dysplasia - a possible biomarker for carcinogenesis of esophageal squamous-cell carcinoma

The tumor suppressor gene product p53 has been detected in a high percentage of esophageal squamous cell carcinoma. To evaluate the role of this protein in carcinogenesis, we examined the p53 overexpression both in esophageal dysplasia and in esophageal squamous cell carcinoma in the same patients. Using anti-p53 antibodies pAb1801 and CM-1, we analyzed immunohistochemically 36 dysplastic lesions from 36 patients with esophageal cancer. Nuclear p53 was detected in 14 of 36 dysplasias (39%). From mild to moderate to severe dysplasia, p53 positivity showed tendency to increase in number. Seventeen of the 36 squamous cell carcinomas showed p53 expression (47%). There was a significant concurrent p53 expression in esophageal dysplasia and its related squamous cell carcinoma (p=0.00345). These results indicate that p53 mutation is closely associated with the initiation of this cancer.