A Role for the Androgen Receptor in Collagen Content of the Skin

Histological and morphological development of the prepuce from birth to prepubertal age

PURPOSE

To study the histological changes of the preputial tissue from birth to prepubertal age in order to define unnoticed morphological changes.

MATERIALS AND METHODS

Prepuce samples were obtained from 79 healthy boys who underwent routine ritual circumcision. Specimens were divided into six groups according to the boys' age: newborn, 0-1 year of age, 2-3 years of age, 4-5 years of age, 6-7 years of age, and 8-9 years of age. Histologic analysis of the specimens was performed by H&E, Masson's trichrome, Verhoeff-Von Gieson, immunohistochemical staining.

RESULTS

Microscopic examinations showed that average epithelial thickness increased after the neonatal period (p=0.001). When collagen fiber density was evaluated, no significant differences between groups were found (p=0.083). When the elastic fibers in the dermis were evaluated, it was determined that the number and thickness of elastic fibers increased with age. Immunohistochemical examinations showed that the number of peripheral nerves marked with S100 was lower in the neonatal period than at other ages (p=0.048). When the vessels marked with CD105 antibody were counted, there was no significant difference between the groups (p=0.078).

CONCLUSIONS

This is the first study to examine the age-related structure of connective tissue elements in the foreskin. Our results showed that the prepuce's prepubertal maturation process is continuous, and the first 2 years of life are appropriate not only in relation to the physiological effects of age but also the optimum structural changes for wound healing, such as vessel diameter, epithelium thickness, peripheral nerve count.

Gender-related differentially expressed genes in pancreatic cancer: possible culprits or accomplices?

Pancreatic cancer (PC) is one of the leading causes of cancer mortality worldwide, and its incidence and mortality rate in several regions is higher in male patients. Although numerous efforts have been made to enhance the clinical outcomes of existing therapeutic regimens, their efficiency is still low, and drug resistance usually occurs in many patients. In addition, the exact underlying molecular basis that makes PC slightly more prevalent among males remains unknown. Providing information regarding the possible association between gender and PC tumorigenesis may offer important clues for how certain molecular cross-talks can affect PC initiation and/or progression. In this study, we used several microarray expression data to identify the common up- and downregulated genes within one specific gender, which were also specified to have binding sites for androgen and/or estrogen receptors. Using functional enrichment analysis among the others, for all the gene sets found in this study, we have shed light on the plausible importance of the androgenic effectors in tumorigenesis, such as the androgen-regulated expression of the GLI transcription factor and the potential role of testosterone in the extracellular matrix (ECM)–cell interaction, which are known for their importance in tumorigenesis. Moreover, we demonstrated that the biological process axon guidance was highlighted regarding the upregulated genes in male patients. Overall, identification of gene candidates as the possible link between gender and PC progression or survival rates may help in developing strategies to reduce the incidence of this cancer.

Anabolic androgenic steroid-induced liver injury: An update

Anabolic androgenic steroids (AASs) are a group of molecules including endogenous testosterone and synthetic derivatives that have both androgenic and anabolic effects. These properties make them therapeutically beneficial in medical conditions such as hypogonadism. However, they are commonly bought illegally and misused for their anabolic, skeletal muscle building, and performance-enhancing effects. Supraphysiologic and long-term use of AASs affects all organs, leading to cardiovascular, neurological, endocrine, gastrointestinal, renal, and hematologic disorders. Hepatotoxicity is one of the major concerns regarding AASs treatment and abuse. Testosterone and its derivatives have been most often shown to induce a specific form of cholestasis, peliosis hepatis, and hepatic benign and malignant tumors. It is currently believed that mechanisms of pathogenesis of these disorders include disturbance of antioxidative factors, upregulation of bile acid synthesis, and induction of hepatocyte hyperplasia. Most toxicity cases are treated with supportive measures and liver function normalizes with discontinuation of AAS. However, some long-term consequences are irreversible. AAS-induced liver injury should be taken in consideration in patients with liver disorders, especially with the increasing unintentional ingestion of supplements containing AAS. In this paper, we review the most current knowledge about AAS-associated adverse effects on the liver, and their clinical presentations, prevalence, and pathophysiological mechanisms.

Factors associated with canine skin extensibility in toy poodles

To assess factors for canine skin extensibility, our study investigated associations between the dogs' skin extension index and the following factors, gender, age, neuter status, weight, coat color and six coat color related gene polymorphisms. Swab samples were collected from 69 toy poodles to extract DNA. The skin extension indices of the lower back and the neck were measured using the following formula: vertical height of the skin fold divided by body length multiplied by 100. The dogs' age, weight, gender, neuter status and coat color were also recorded, as well as polymorphisms of the following six selected coat color related genes, Melanocortin 1 receptor, Tyrosinase-related protein 1, Melanophilin, Canine β-defensin-1, Major Facilitator Superfamily Domain Containing 12 and Agouti-signaling protein (ASIP). Univariable analysis showed there was a meaningful association between the lower back skin extension index and both gender and age (P<0.001 and P=0.048, respectively). Also, there was a possible association between the lower back skin extension index and ASIP Single nucleotide polymorphism (SNP) (R96C) (P=0.078). Linear model analysis showed there was a significant association between the lower back skin extension index and gender (P<0.001), and there was a tendency of the association between the lower back skin extension index and ASIP SNP (R96C) (P=0.098). In addition, there was an association between gender and age for the skin extension index. (P=0.048). Therefore, these results suggest that a greater risk of skin extensibility in toy poodle could be related to being female and the ASIP SNP (R96C), because these factors were associated with higher lower back skin extension index.

How to define the experimental conditions of skin permeation assays for drugs presenting biopharmaceutical limitations? The experience with testosterone

Cutaneous permeation assays are crucial to attest the performance or bioequivalence of topical or transdermal products. Although the official guidelines (e.g., FDA/EMA) play a key role in harmonizing the experimental design, alternative methods are often proposed by the scientific community, which makes it difficult to compare results from different studies. In this review, permeation assays with testosterone (TST) were selected to show this high variability in drug transport rate. The main sources of variation discussed were tissue thickness, animal model, donor and receptor fluid constitution, type of solubilizing agent used in aqueous fluids, drug concentration, degree of supersaturation, skin lipid content, number of experimental times and the physical-chemical stability of the molecule in test fluids. This variation becomes even more critical for molecules that present biopharmaceutical limitations such as TST. In addition, the skin presents specific receptors for this hormone due to its physiological action in this region of the body, which makes the evaluation of the TST transport rate in this tissue even more challenging. The impact of each experimental parameter mentioned above on the flux or permeation coefficient of TST is discussed in detail in the review. Assays used to evaluate tissue integrity are also presented.

The contradictory role of androgens in cutaneous and major burn wound healing

Wound healing is a complex process involving four overlapping phases: haemostasis, inflammation, cell recruitment and matrix remodeling. In mouse models, surgical, pharmacological and genetic approaches targeting androgen actions in skin have shown that androgens increase interleukin-6 and tumor necrosis factor-α production and reduce wound re-epithelization and matrix deposition, retarding cutaneous wound healing. Similarly, clinical studies have shown that cutaneous wound healing is slower in men compared to women. However, in major burn injury, which triggers not only local wound-healing processes but also systemic hypermetabolism, the role of androgens is poorly understood. Recent studies have claimed that a synthetic androgen, oxandrolone, increases protein synthesis, improves lean body mass and shortens length of hospital stay. However, the possible mechanisms by which oxandrolone regulates major burn injury have not been reported. In this review, we summarize the current findings on the roles of androgens in cutaneous and major burn wound healing, as well as androgens as a potential therapeutic treatment option for patients with major burn injuries.

Extracellular Superoxide Dismutase Prevents Skin Aging by Promoting Collagen Production through the Activation of AMPK and Nrf2/HO-1 Cascades

With aging, the skin becomes thin and drastically loses collagen. Extracellular superoxide dismutase (EC-SOD), also known as superoxide dismutase (SOD) 3, is the major SOD in the extracellular matrix of the tissues and is well-known to maintain the reduction‒oxidation homeostasis and matrix components of such tissues. However, the role of EC-SOD in aging-associated reductions of skin thickness and collagen production is not well-studied. In this study, we compared the histological differences in the dorsal skin of EC-SOD‒overexpressing transgenic mice (Sod3^+/+) of different age groups with that in wild-type mice and also determined the underlying signaling mechanism. Our data showed that the skin thickness in Sod3^+/+ mice significantly increased with aging compared with that in wild-type male mice. Furthermore, Sod3^+/+ mice had promoted collagen production through the activation of adenosine monophosphate-activated protein kinase and Nrf2/HO-1 pathways in aged mice. Interestingly, subcutaneous injection of adeno-associated virus‒overexpressing EC-SOD exhibited increased skin thickness and collagen expression. Furthermore, combined recombinant EC-SOD and dihydrotestosterone treatment synergistically elevated collagen production through the activation of TGFβ in human dermal fibroblasts. Altogether, these results showed that EC-SOD prevents skin aging by promoting collagen production in vivo and in vitro. Therefore, we propose that EC-SOD may be a potential therapeutic target for antiaging in the skin.

Multiscale molecular profiling of pathological bone resolves sexually dimorphic control of extracellular matrix composition

Collagen assembly during development is essential for successful matrix mineralisation, which determines bone quality and mechanocompetence. However, the biochemical and structural perturbations that drive pathological skeletal collagen configuration remain unclear. Deletion of vascular endothelial growth factor (VEGF; also known as VEGFA) in bone-forming osteoblasts (OBs) induces sex-specific alterations in extracellular matrix (ECM) conformation and mineralisation coupled to vascular changes, which are augmented in males. Whether this phenotypic dimorphism arises as a result of the divergent control of ECM composition and its subsequent arrangement is unknown and is the focus of this study. Herein, we used murine osteocalcin-specific Vegf knockout (OcnVEGFKO) and performed ex vivo multiscale analysis at the tibiofibular junction of both sexes. Label-free and non-destructive polarisation-resolved second-harmonic generation (p-SHG) microscopy revealed a reduction in collagen fibre number in males following the loss of VEGF, complemented by observable defects in matrix organisation by backscattered electron scanning electron microscopy. This was accompanied by localised divergence in collagen orientation, determined by p-SHG anisotropy measurements, as a result of OcnVEGFKO. Raman spectroscopy confirmed that the effect on collagen was linked to molecular dimorphic VEGF effects on collagen-specific proline and hydroxyproline, and collagen intra-strand stability, in addition to matrix carbonation and mineralisation. Vegf deletion in male and female murine OB cultures in vitro further highlighted divergence in genes regulating local ECM structure, including Adamts2, Spp1, Mmp9 and Lama1. Our results demonstrate the utility of macromolecular imaging and spectroscopic modalities for the detection of collagen arrangement and ECM composition in pathological bone. Linking the sex-specific genetic regulators to matrix signatures could be important for treatment of dimorphic bone disorders that clinically manifest in pathological nano- and macro-level disorganisation. This article has an associated First Person interview with the first author of the paper.

Morphological and Functional Changes in Skin of Adult Male Rats Chronically Treated with Letrozole, a Nonsteroidal Inhibitor of Cytochrome P450 Aromatase

Skin is a target for hormones and a site of hormone production. Aromatase inhibitors such as letrozole reduce circulating estrogen. The aim of the study was to investigate the morphology of the dermis and immunoexpression of androgen receptor (AR), estrogen receptor α and β (ERα, ERβ), luteinizing hormone receptor (LHR), follicle-stimulating hormone receptor (FSHR), and cytochrome P450 aromatase (P450arom) in male rats with a deficit of estradiol. Experiments were performed on skin of 12 male rats. Rats in the experimental group received per os letrozole for 6 months. For morphological analysis, van Gieson, Sirius Red and orcein staining of sections was performed. In immunohistochemistry, reactions with specific antibodies (anti-P450arom, LHR, FSHR, ERα, ERβ) were used. In morphometric analysis, sections were stained with hematoxylin and eosin. Differences between groups were assessed by Mann-Whitney U-test. There were no differences in the diameter of collagen fibers. The dermis of letrozole-treated animals showed areas without collagen fibers, and expression of P450arom, ERα and ERβ was diminished in the skin of these animals. This study indicates that estrogens exert an effect via ERs that has a role in maintaining proper skin morphology in males, together with androgen. This is also the first documented expression of FSHR in the skin of male rats.

Proline-dependent regulation of collagen metabolism

This review is focused on recent data on the role of proline (Pro) in collagen biosynthesis and cellular metabolism. It seems obvious that one of the main substrates for collagen biosynthesis Pro is required to form collagen molecule. The question raised in this review is whether the Pro for collagen biosynthesis is synthesized "de novo", comes directly from degraded proteins or it is converted from other amino acids. Recent data provided evidence that extracellular Pro (added to culture medium) had significant, but relatively little impact on collagen biosynthesis in fibroblasts (the main collagen synthesized cells) cultured in the presence of glutamine (Gln). However, extracellular Pro drastically increased collagen biosynthesis in the cells cultured in Gln-free medium. It suggests that Pro availability determines the rate of collagen biosynthesis and demand for Pro in fibroblasts is predominantly met by conversion from Gln. The potential mechanism of this process as well as possible implication of this knowledge in pharmacotherapy of connective tissue diseases is discussed in this review.

Facial aging trajectories: A common shape pattern in male and female faces is disrupted after menopause

Objectives

Despite variation in lifestyle and environment, first signs of human facial aging show between the ages of 20–30 years. It is a cumulative process of changes in the skin, soft tissue, and skeleton of the face. As quantifications of facial aging in living humans are still scarce, we set out to study age‐related changes in three‐dimensional facial shape using geometric morphometrics.

Materials and methods

We collected surface scans of 88 human faces (aged 26–90 years) from the coastal town Split (Croatia) and neighboring islands. Based on a geometric morphometric analysis of 585 measurement points (landmarks and semilandmarks), we modeled sex‐specific trajectories of average facial aging.

Results

Age‐related facial shape change was similar in both sexes until around age 50, at which time the female aging trajectory turned sharply. The overall magnitude of facial shape change (aging rate) was higher in women than men, especially in early postmenopause. Aging was generally associated with a flatter face, sagged soft tissue (“broken” jawline), deeper nasolabial folds, smaller visible areas of the eyes, thinner lips, and longer nose and ears. In postmenopausal women, facial aging was best predicted by the years since last menstruation and mainly attributable to bone resorption in the mandible.

Discussion

With high spatial and temporal resolution, we were able to extract a shared facial aging pattern in women and men, and its divergence after menopause. This fully quantitative three‐dimensional analysis of human facial aging may not only find applications in forensic and ancient human facial reconstructions, but shall include lifestyle and endocrinological measures, and also reach out to studies of social perception.

Abrogation of transforming growth factor-β-induced tissue fibrosis in TBRIcaCol1a2Cre transgenic mice by the second generation tyrosine kinase inhibitor SKI-606 (Bosutinib)

Transforming growth factor-β (TGF-β) plays a crucial role in the pathogenesis of Systemic Sclerosis (SSc) and other fibrotic disorders. TGF-β-mediated c-Abl and Src kinase activation induces strong profibrotic cascade signaling. The purpose of this study was to test in vivo the antifibrotic activity of Bosutinib (SKI-606), a second generation c-Abl and Src kinase inhibitor, on TGF-β induced cutaneous and pulmonary fibrosis. For this purpose, we employed the TBRIcaCol1a2Cre transgenic mice expressing an inducible constitutively active TGF-β receptor 1 constitutively activated by Col1a promoter-mediated Cre recombinase. The mice were treated parenterally with 2.5, 5.0 or 10.0 mg/kg/day of Bosutinib for 42 days. Skin and lungs from control and Bosutinib-treated mice (n = 6 per group) were assessed by histopathology, measurement of tissue hydroxyproline content, PCR analysis of tissue fibrosis associated gene expression, and evidence of myofibroblast activation. Mice with constitutive TGF-β-1 signaling displayed severe cutaneous and pulmonary fibrosis. Bosutinib administration decreased collagen deposition and hydroxyproline content in the dermis and lungs in a dose-dependent manner. Bosutinib also reversed the marked increase in profibrotic and myofibroblast activation-associated gene expression. These results demonstrate that constitutive TGF-β-1-signaling-induced cutaneous and pulmonary fibrosis were abrogated in a dose-related manner following parenteral administration of the c-Abl and Src tyrosine kinase inhibitor, Bosutinib. These results indicate that Bosutinib may be a potential therapeutic agent for tissue fibrosis in SSc and other fibroproliferative disorders.

The antiviral drug tenofovir, an inhibitor of Pannexin-1-mediated ATP release, prevents liver and skin fibrosis by downregulating adenosine levels in the liver and skin

Background

Fibrosing diseases are a leading cause of morbidity and mortality worldwide and, therefore, there is a need for safe and effective antifibrotic therapies. Adenosine, generated extracellularly by the dephosphorylation of adenine nucleotides, ligates specific receptors which play a critical role in development of hepatic and dermal fibrosis. Results of recent clinical trials indicate that tenofovir, a widely used antiviral agent, reverses hepatic fibrosis/cirrhosis in patients with chronic hepatitis B infection. Belonging to the class of acyclic nucleoside phosphonates, tenofovir is an analogue of AMP. We tested the hypothesis that tenofovir has direct antifibrotic effects in vivo by interfering with adenosine pathways of fibrosis using two distinct models of adenosine and A2AR-mediated fibrosis.

Methods

Thioacetamide (100mg/kg IP)-treated mice were treated with vehicle, or tenofovir (75mg/kg, SubQ) (n = 5–10). Bleomycin (0.25U, SubQ)-treated mice were treated with vehicle or tenofovir (75mg/kg, IP) (n = 5–10). Adenosine levels were determined by HPLC, and ATP release was quantitated as luciferase-dependent bioluminescence. Skin breaking strength was analysed and H&E and picrosirus red-stained slides were imaged. Pannexin-1expression was knocked down following retroviral-mediated expression of of Pannexin-1-specific or scrambled siRNA.

Results

Treatment of mice with tenofovir diminished adenosine release from the skin of bleomycin-treated mice and the liver of thioacetamide-treated mice, models of diffuse skin fibrosis and hepatic cirrhosis, respectively. More importantly, tenofovir treatment diminished skin and liver fibrosis in these models. Tenofovir diminished extracellular adenosine concentrations by inhibiting, in a dose-dependent fashion, cellular ATP release but not in cells lacking Pannexin-1.

Conclusions

These studies suggest that tenofovir, a widely used antiviral agent, could be useful in the treatment of fibrosing diseases.

Adenosine A2a Receptor Blockade Diminishes Wnt/β-Catenin Signaling in a Murine Model of Bleomycin-Induced Dermal Fibrosis

Adenosine A_2a receptor (A_2aR) stimulation promotes the synthesis of collagens I and III, and we have recently demonstrated that there is crosstalk between the A_2aR and WNT/β-catenin signaling pathway. In in vitro studies, A_2aR signaling for collagen III expression was mediated by WNT/β-catenin signaling in human dermal fibroblasts; we further verified whether the crosstalk between A_2aR and Wnt/β-catenin signaling was involved in diffuse dermal fibrosis in vivo. Wnt-signaling reporter mice (Tcf/Lef:H2B-GFP) were challenged with bleomycin and treated with the selective A_2aR antagonist istradefylline (KW6002) or vehicle. Dermal fibrosis was quantitated and nuclear translocation of β-catenin in fibroblasts was assessed by double-staining for Green fluorescent protein or dephosphorylated β-catenin or β-catenin phosphorylated at Ser552, and vimentin. KW6002 significantly reduced skin thickness, skinfold thickness, breaking tension, dermal hydroxyproline content, myofibroblast accumulation, and collagen alignment in bleomycin-induced dermal fibrosis. Also, there was increased expression of Tcf/Lef:H2B-GFP reporter in bleomycin-induced dermal fibrosis, an effect that was diminished by treatment with KW6002. Moreover, KW6002 significantly inhibited nuclear translocation of Tcf/Lef:H2B-GFP reporter, as well as dephosphorylated β-catenin and β-catenin phosphorylated at Ser552. Our work supports the hypothesis that pharmacologic blockade of A_2aR inhibits the WNT/β-catenin signaling pathway, contributing to its capacity to inhibit dermal fibrosis in diseases such as scleroderma.

Postnatal changes and sexual dimorphism in collagen expression in mouse skin

To investigate sexual dimorphism and postnatal changes in skin collagen expression, mRNA levels of collagens and their regulatory factors in male and female skin were examined during the first 120 days of age by quantitative realtime PCR. Levels of mRNAs encoding extracellular matrices did not show any differences between male and female mice until day 15. Col1a1 and Col1a2 mRNAs noticeably increased at day 30 and remained at high levels until day 120 in male mice, while those in female mice remained at low levels during the period. Consistent with the mRNA expression, pepsin-soluble type I collagen contents in skin was very high in mature male as compared to female. Col3a1 mRNA in male mice also showed significantly high level at day 120 as compared to female. On the other hand, expression of mRNAs encoding TGF-ßs and their receptors did not show apparent sexual dimorphism although small significant differences were observed at some points. Castration at 60 days of age resulted in a significant decrease in type I collagen mRNA expression within 3 days, and noticeably decreased expression of all fibril collagen mRNAs examined within 14 days, while administration of testosterone tube maintained the mRNA expression at high levels. Despite the in vivo effect of testosterone, administration of physiological concentrations of testosterone did not affect fibril collagen mRNA expression in either human or mouse skin fibroblasts in vitro, suggesting that testosterone does not directly affect collagen expression in fibroblasts. In summary, present study demonstrated dynamic postnatal changes in expression of collagens and their regulatory factors, and suggest that testosterone and its effects on collagen expression are responsible for the skin sexual dimorphism but the effects of testosterone is not due to direct action on dermal fibroblasts.

Aging in the Male Face: Intrinsic and Extrinsic Factors

BACKGROUND

Gender is one of the most significant factors that influence facial anatomy and behavior, both key factors in the aging process.

OBJECTIVE

To review male facial anatomy, physiology, and behavior and how it contributes to sexual dimorphism in facial aging.

METHODS

A MEDLINE search was performed for publications on gender differences in facial anatomy, aging, cutaneous physiology, and behavior.

RESULTS

There are differences in both intrinsic and extrinsic aging factors in men. Men have a thicker epidermis and dermis with more active cutaneous appendages including hair growth. Male skin has a reduced antioxidant capacity and increased ultraviolet-induced immunosuppression. The male face is larger and has a unique square shape with less subcutaneous soft tissue, especially at the medial cheek. Men are also more prone to smoking and exhibiting poor sun-protective behavior. The differences in intrinsic and extrinsic aging factors contribute to poor facial aging in men. Men develop more severe rhytides in a unique pattern, show increased periocular aging changes, and are more prone to hair loss.

CONCLUSION

This review provides insight into the factors contributing to accelerated male facial aging. Understanding gender differences in aging will help physicians tailor cosmetic treatments for men and minimize extrinsic aging factors.

Androgen actions in mouse wound healing: Minimal in vivo effects of local antiandrogen delivery

The aims of this work were to define the role of androgens in female wound healing and to develop and characterize a novel wound dressing with antiandrogens. Androgens retard wound healing in males, but their role in female wound healing has not been established. To understand androgen receptor (AR)-mediated androgen actions in male and female wound healing, we utilized the global AR knockout (ARKO) mouse model, with a mutated AR deleting the second zinc finger to disrupt DNA binding and transcriptional activation. AR inactivation enhanced wound healing rate in males by increasing re-epithelialization and collagen deposition even when wound contraction was eliminated. Cell proliferation and migration in ARKO male fibroblasts was significantly increased compared with wild-type (WT) fibroblasts. However, ARKO females showed a similar healing rate compared to WT females. To exploit local antiandrogen effects in wound healing, while minimizing off-target systemic effects, we developed a novel electrospun polycaprolactone (PCL) scaffold wound dressing material for sustained local antiandrogen delivery. Using the antiandrogen hydroxyl flutamide (HF) at 1, 5, and 10 mg/mL in PCL scaffolds, controlled HF delivery over 21 days significantly enhanced in vitro cell proliferation of human dermal fibroblasts and human keratinocytes. HF-PCL scaffolds also promoted in vivo wound healing in mice compared with open wounds but not to PCL scaffolds.

Androgen receptor actions modify skin structure and chemical carcinogen-induced skin cancer susceptibility in mice

Men are significantly more susceptible to non-melanoma skin cancers than women, and the androgen receptor (AR) is widely distributed in the skin, suggesting a ro\le for androgens acting via AR. Therefore, we explored the role of androgen action via AR in susceptibility to experimental 7,12-dimethylbenz[a]anthracene (DMBA)-induced skin carcinogenesis and in skin structural development of male and female mice. We demonstrate that both the male gender and androgen action via AR modify the susceptibility to carcinogen-induced skin cancer, but the effect depends on the carcinogenesis model used. Following systemic DMBA exposure, males were significantly (p < 0.05) more susceptible to DMBA-induced experimental skin cancer than females and AR inactivation significantly delayed cancer detection in both male (median time to palpable tumours 19 vs. >35 weeks (wild-type [WT] vs. AR knockout [ARKO], p < 0.001) and female (27 vs. >35 weeks, p = 0.008)) mice. In contrast, following DMBA/12-O-tetradecanoylphorbol-13-acetate (TPA)-induced multistage local skin carcinogenesis, AR inactivation protected against formation of DMBA-induced skin cancers in both male and female mice. The skin structure was also affected by gender effect as well as the AR inactivation and could at least partly explain the different responses between the carcinogenesis models (systemic vs. topical). In addition, AR inactivation modified Cox-1 and Cox-2 expression in the skin, suggesting possible molecular mechanism for the AR effect on skin. Finally, some gender differences are observed also in ARKO mice insensitive to androgens, suggesting that factors other than androgens also play a role in gender-dependent skin carcinogenesis.

Decreased expression of P54(nrb) /NonO correlates with collagen deposition and fibrosis in human aortic dissection

AIMS

Aortic dissection (AD) is characterized by changes in the extracellular matrix, including fibrosis with collagen production. P54(nrb) /NonO is known to be involved in collagen formation. In this study, we examined whether AD is associated with abnormal P54(nrb) /NonO expression.

METHODS AND RESULTS

Aortic specimens and serum were obtained from 10 patients with AD and 10 controls. In-vitro cultures of vascular smooth muscle cells (VSMCs) and adventitial fibroblasts (AFs) were obtained from organ donors. P54(nrb) /NonO protein and mRNA levels were determined by Western blot, immunohistochemistry and quantitative real-time reverse transcription-polymerase chain reaction (quantitative real-time RT-PCR). To evaluate collagen expression, we stained tissue sections with Masson's trichrome. Serum concentration of TNF-α was determined by enzyme-linked immunosorbent assay (ELISA). Aortic P54(nrb) /NonO protein and mRNA were decreased in AD patients, compared with controls. Decreased P54(nrb) /NonO mRNA correlated significantly with increased collagen deposition and fibrosis in AD aortas. In VSMCs and AFs from normal human aortas, P54(nrb) /NonO was expressed strongly and localized to the nucleus.

CONCLUSIONS

Patients with AD exhibited significantly decreased expression of P54(nrb) /NonO. The significant correlation between P54(nrb) /NonO and collagen may point to novel thinking about collagen metabolism research in AD aorta.

Collagen content in skin and internal organs of the tight skin mouse: an animal model of scleroderma

The Tight Skin mouse is a genetically induced animal model of tissue fibrosis caused by a large in-frame mutation in the gene encoding fibrillin-1 (Fbn-1). We examined the influence of gender on the collagen content of tissues in C57BL/6J wild type (+/+) and mutant Tight Skin (Tsk/+) mice employing hydroxyproline assays. Tissue sections were stained with Masson's trichrome to identify collagen in situ. Adult Tsk/+ mice skin contains ~15% more collagen, on average, than skin from +/+ mice of the same gender. The heart of Tsk/+ males had significantly more collagen than that of +/+ males. No significant gender differences were found in lungs and kidney collagen content. Overall, the collagen content of Tsk/+ males and +/+ males was higher than that of their Tsk/+ and +/+ female counterparts, respectively. Our data confirm increased deposition of collagen in skin and hearts of Tsk/+ mice; however, the effects of the Tsk mutation on collagen content are both tissue specific and gender specific. These results indicate that comparative studies of collagen content between normal and Tsk/+ mice skin and internal organs must take into account gender differences caused by expression of the androgen receptor.

Androgen receptor (AR) pathophysiological roles in androgen-related diseases in skin, bone/muscle, metabolic syndrome and neuron/immune systems: lessons learned from mice lacking AR in specific cells

The androgen receptor (AR) is expressed ubiquitously and plays a variety of roles in a vast number of physiological and pathophysiological processes. Recent studies of AR knockout (ARKO) mouse models, particularly the cell type- or tissue-specific ARKO models, have uncovered many AR cell type- or tissue-specific pathophysiological roles in mice, which otherwise would not be delineated from conventional castration and androgen insensitivity syndrome studies. Thus, the AR in various specific cell types plays pivotal roles in production and maturation of immune cells, bone mineralization, and muscle growth. In metabolism, the ARs in brain, particularly in the hypothalamus, and the liver appear to participate in regulation of insulin sensitivity and glucose homeostasis. The AR also plays key roles in cutaneous wound healing and cardiovascular diseases, including atherosclerosis and abdominal aortic aneurysm. This article will discuss the results obtained from the total, cell type-, or tissue-specific ARKO models. The understanding of AR cell type- or tissue-specific physiological and pathophysiological roles using these in vivo mouse models will provide useful information in uncovering AR roles in humans and eventually help us to develop better therapies via targeting the AR or its downstream signaling molecules to combat androgen/AR-related diseases.

c-MYC-induced sebaceous gland differentiation is controlled by an androgen receptor/p53 axis

Although the sebaceous gland (SG) plays an important role in skin function, the mechanisms regulating SG differentiation and carcinoma formation are poorly understood. We previously reported that c-MYC overexpression stimulates SG differentiation. We now demonstrate roles for the androgen receptor (AR) and p53. MYC-induced SG differentiation was reduced in mice lacking a functional AR. High levels of MYC triggered a p53-dependent DNA damage response, leading to accumulation of proliferative SG progenitors and inhibition of AR signaling. Conversely, testosterone treatment or p53 deletion activated AR signaling and restored MYC-induced differentiation. Poorly differentiated human sebaceous carcinomas exhibited high p53 and low AR expression. Thus, the consequences of overactivating MYC in the SG depend on whether AR or p53 is activated, as they form a regulatory axis controlling proliferation and differentiation.

Age and skin site related differences in steroid metabolism in male skin point to a key role of sebocytes in cutaneous hormone metabolism

Hormone concentrations decline with aging. Up to now it was not clear, whether the decrease of hormone concentrations in blood samples are also present in cutaneous suction blister fluids, and whether skin from different anatomical sites shows different hormone concentrations.

Analysis of suction blister fluids and paired blood samples from young (mean 27.8 y) and old (mean 62.6 y) male subjects by UPLC-MS/MS showed that DHEA concentration in blood samples was age-dependently significantly reduced, but increased in suction blister fluids, while androstenedione behaved in an opposite manner to DHEA. Testosterone decreased age-dependently in blood samples and in suction blister fluids. Regarding skin sites, DHEA was lower in samples from upper back compared with samples from the forearm. In contrast, the concentrations of androstenedione and testosterone were higher in samples from upper back.

In vitro analyses showed that SZ95 sebocytes, but neither primary fibroblasts nor keratinocytes, were able to use DHEA as precursor for testosterone biosynthesis, which was confirmed by expression analysis of 3β-hydroxysteroiddehydrogenase in skin biopsies.

In conclusion, we show an inverse pattern of DHEA and androstenedione concentrations in blood vs. suction blister fluids, highlighting age-dependent changes of dermal testosterone biosynthesis, and a stronger metabolism in young skin. Furthermore, sebocytes play a central role in cutaneous androgen metabolism.

A role for estrogen receptor-α and estrogen receptor-β in collagen biosynthesis in mouse skin

Hormonal regulation of the dermal collagenous extracellular matrix plays a key role in maintaining proper tissue homeostasis, however the factors and pathways involved in this process are not fully defined. This study investigated the role of estrogen receptors (ERs) in the regulation of collagen biosynthesis in mice lacking ERα or ERβ. Collagen content was significantly increased in the skin of ΕRα^-/- mice as measured by acetic acid extraction and the hydroxyproline assay and correlated with the decreased levels of MMP-15 and elevated collagen production by ΕRα^-/- fibroblasts. In contrast, collagen content was decreased in the skin of ERβ^-/- mice despite markedly increased collagen production by ERβ^-/- fibroblasts. However, expression of several matrix metalloproteinases (MMPs), including MMP-8 and -15 was significantly elevated suggesting increased degradation of dermal collagen. Furthermore, ERβ^-/- mice were characterized by significantly reduced levels of small leucine proteoglycans (SLRPs), lumican and decorin, leading to the defects in collagen fibrillogenesis and possibly less stable collagen fibrils. ERα^-/- mice also exhibited fibrils with irregular structure and size, which correlated with increased levels of lumican and decorin. Together, these results demonstrate distinct functions of estrogen receptors in the regulation of collagen biosynthesis in mouse skin in vivo.

The evolution of the multicoloured face of mandrills: insights from the perceptual space of colour vision

Multicomponent signals consist of several traits that are perceived as a whole. Although many animals rely on multicomponent signals to communicate, the selective pressures shaping these signals are still poorly understood. Previous work has mainly investigated the evolution of multicomponent signals by studying each trait individually, which may not accurately reflect the selective pressures exerted by the holistic perception of signal receivers. Here, we study the design of the multicoloured face of an Old World primate, the mandrill (Mandrillus sphinx), in relation to two aspects of signalling that are expected to be selected by receivers: conspicuousness and information. Using reflectance data on the blue and red colours of the faces of 34 males and a new method of hue vectorisation in a perceptual space of colour vision, we show that the blue hue maximises contrasts to both the red hue and the foliage background colouration, thereby increasing the conspicuousness of the whole display. We further show that although blue saturation, red saturation and the contrast between blue and red colours are all correlated with dominance, dominance is most accurately indicated by the blue-red contrast. Taken together our results suggest that the evolution of blue and red facial colours in male mandrills are not independent and are likely driven by the holistic perception of conspecifics. In this view, we propose that the multicoloured face of mandrills acts as a multicomponent signal. Last, we show that information accuracy increases with the conspicuousness of the whole display, indicating that both aspects of signalling can evolve in concert.

Sex steroid receptors in human lung diseases

Several epidemiological studies have reported that gender differences exist in clinical and biological manifestations of human lung diseases. In particular, women are far more likely to develop both neoplastic and non-neoplastic lung diseases than men. This gender difference above suggests that sex steroid may be involved in the pathogenesis of various lung diseases. These sex steroids mediate their effects through sex steroid receptors including estrogen receptors (ER) i.e. ERα and ERβ progesterone receptors (PR) i.e. PR-A and PR-B and androgen receptors (ARs), all of which have been reported to be expressed in lung tissue. Therefore it becomes important to clarify the potential roles of sex steroid receptor in both neoplastic and non-neoplastic lung diseases toward improved treatment options for the patients. In this review, we summarized a number of studies in humans and experimental animals that have identified possible roles of sex steroids in respiratory physiology and pathology.

Cutaneous resonance running time varies with age, body site and gender in a normal Chinese population

BACKGROUND/OBJECTIVES

One phenomenon of skin aging is loss of cutaneous elasticity. Measurement of cutaneous resonance running time (CRRT) is a method to assess skin elasticity. Yet, information regarding the directional changes of CRRT associated with age, body sites and gender is not yet available. In the present study, we assessed whether changes in CRRT vary with age, body sites and gender in a normal Chinese population.

METHODS

A Reviscometer was used to measure CRRTs in various directions on the left dorsal hand, the forehead and the left canthus of 806 normal Chinese volunteers, aged 2.5-94 years.

RESULTS

With aging, CRRTs decreased in all directions on the hand, the forehead and the canthus. A more dramatic reduction in CRRTs on the forehead and the canthus was observed in both the 2-8 and the 3-9 o'clock directions. CRRTs in males aged 11-20 years were longer than those in females in some directions on all three body sites. Females aged between 21 years and 40 years showed longer CRRTs than males in some directions of the hand. There were no gender differences in subjects aged 0-10 (except on the canthus) and those over 80 years old.

CONCLUSION

CRRTs vary with age, body sites and gender.

Lung defects in neonatal and adult stromal-derived factor-1 conditional knockout mice

Stromal-derived factor (SDF)-1/CXCL12 is a cytokine that is involved in organogenesis, hematopoiesis, chemoattraction, and wound healing. An SDF-1 knockout mouse (SDF-1(-/-)) has provided important insights into the role of SDF-1 in fetal development. Because the SDF-1 knockout is lethal in the perinatal period, we have created a conditional SDF-1 knockout mouse. In the present study, we induced conditionally knocked out SDF-1 in neonatal mice and found that lung development was compromised; neonatal lungs showed increased alveolar airspace and abnormal ultrastructure. Conditional knockout of SDF-1 in adult mice resulted in an emphysemic morphology, with increased alveolar airspace and thickened alveolar septa. Fluorescence angiography showed pulmonary vessel hyperdilation. To determine whether the hyperdilation involved nitric oxide, we inhibited endothelial nitric oxide synthase (eNOS) with N (G)-nitro-L- arginine methyl ester. This resulted in the inhibition of pulmonary vessel hyperdilation. Western blot results showed increased phosphorylation of eNOS in our induced SDF-1 knockout mice, indicating that eNOS is normally repressed in the presence of SDF-1, and that activation of eNOS contributes to pulmonary pathology. Thus, a conditional knockout mouse has been successfully created for SDF-1; initial characterization indicates that SDF-1 is intimately involved in lung development and physiology.

Effect of long-term topical application of dehydroepiandrosterone (DHEA) and oral estrogens on morphology, cell proliferation, procollagen A1 and androgen receptor levels in rat skin

BACKGROUND

After cessation of estrogen secretion by the ovaries at menopause, all estrogens and almost all androgens acting in the skin of postmenopausal women are synthesized locally from dehydroepiandrosterone (DHEA), a prohormone of adrenal origin that progressively declines with age.

OBJECTIVE

To better understand the effects of DHEA on the skin, ovariectomized (OVX) rats were treated for 9 months with local topical application of DHEA compared with oral conjugated equine estrogens.

MATERIALS AND METHODS

Morphological evaluation, immunohistochemistry for androgen receptor (AR) and Cdc47 proliferation marker, and in situ hybridization for procollagen A1 were performed on dorsal skin.

RESULTS

Local topical DHEA application increased the thickness of the granular cell layer and total epidermis in OVX animals, whereas systemic estrogens had no significant effect. Although DHEA did not affect total dermal thickness, a 190% increase in dermal procollagen A1 mRNA was observed. Moreover, DHEA treatment decreased hypodermal thickness by 47% and increased skin muscle thickness by 58%. In the epidermis, DHEA induced a non-significant increase in cell proliferation, whereas AR labeling was increased in both the epidermis and dermis by DHEA.

CONCLUSIONS

Although estrogens did not significantly modify any of the above-mentioned parameters, the androgenic action of DHEA induced significant changes in all skin layers, without any sign of toxicity or lack of tolerance to DHEA after a 9-month local application of 4% (80 mg/kg) DHEA on the skin.

Effect of dihydrotestosterone on cultured human tenocytes from intact supraspinatus tendon

The role of hormones in the pathogenesis of tendinopathy is not well recognised, even though the use of anabolic steroids is correlated with a higher incidence of spontaneous tendon ruptures. The aim of this study was to investigate the effects of dihydrotestosterone (DHT) on human tenocyte cultures from the intact supraspinatus tendon of male subjects. Cultured human tenocytes were seeded into culture plates at a density of 5 x 10(4) cells per well and incubated for 24 h. Then, 10(-9) M-10(-7) M DHT or Dulbecco's modified Eagle's medium (DMEM) only (control) was added to the culture plate wells. Cell morphology assessment and cell proliferation tests were performed 48, 72 and 96 h after DHT treatment. DHT-treated tenocytes showed an increased proliferation rate at DHT concentration higher than 10(-8) M. Differences in cell numbers between control and DHT-treated cells were statistically significant (P < 0.05) after 48 and 72 h of treatment with DHT concentrations of 10(-8) and 10(-7) M. The tenocytes treated with DHT (10(-8) and 10(-7) M) became more flattened and polygonal compared to control cells that maintained their fibroblast-like appearance during the experiment at each observation time. In conclusion, in vitro, progressive increasing concentration of DHT at doses greater than 10(-8) M had direct effects on male human tenocytes, increasing cell number after 48 and 72 h of treatment, and leading to a dedifferentiated phenotype after 48 h of treatment. This effect can be important during tendon-healing and repair, when active proliferation is required. Our results represent preliminary evidence for a possible correlation between testosterone abuse and shoulder tendinopathy.

Caffeine improves barrier function in male skin

The influence of androgens, especially testosterone and its effector dihydrotestosterone, results in a constitutive disadvantage for male skin, e.g. reduced viability of hair at the scalp and reduced epidermal permeability barrier repair capacity. Dihydrotestosterone can act, among others, as an adenyl cyclase inhibitor. Caffeine on the other hand is an inexpensive and (in regular doses) harmless substance used in various cosmetic products, which can act as a phosphodiesterase inhibitor. To prove the hypothesis that caffeine as a phosphodiesterase inhibitor is able to override testosterone-induced effects on barrier function, we performed a double-blind placebo controlled study with healthy volunteers. In this study, 0.5% caffeine in a hydroxyethylcellulose gel preparation (HEC) was applied on one forearm, HEC without caffeine on the other forearm of male and female volunteers for 7 days and transepidermal water loss (TEWL) was measured before and at the end of the treatment period. Basal TEWL did not differ significantly between male and female subjects but the application of caffeine significantly reduced TEWL in male skin compared with female skin. We conclude that caffeine is beneficial for barrier function in male skin.

Hormonal influences on lung function and response to environmental agents: lessons from animal models of respiratory disease

Numerous studies in humans and experimental animals have identified considerable sex differences in respiratory physiology and in the response of the lung to environmental agents. These differences appear to be mediated, at least in part, by sex hormones and their nuclear receptors. Moreover, animal models are increasingly used to study pathogenic mechanisms and test potential therapies for a variety of human lung diseases, many of which appear to be influenced by sex and sex hormones. In this article, data are summarized from studies of lung function and disease in which sex differences have been observed. Specific attention is paid to animal models of acute lung injury, nonallergic and allergic lung inflammation, and lung fibrosis. It is anticipated that continued investigation of the role of sex and sex hormones in animal models will provide valuable insight into the pathogenesis and potential treatments for a variety of acute and chronic human lung diseases.

Flutamide inhibits nifedipine- and interleukin-1 beta-induced collagen overproduction in gingival fibroblasts

BACKGROUND AND OBJECTIVE

To understand the role of the androgen receptor in gingival overgrowth, the effects of flutamide on interleukin-1 beta- and nifedipine-induced gene expression of connective tissue growth factor (CTGF/CCN2) and collagen production in gingival fibroblasts were examined.

MATERIAL AND METHODS

Gingival fibroblasts from healthy subjects and patients with dihydropyridine-induced gingival overgrowth (DIGO) were used. Confluent cells were treated with nifedipine, interleukin-1 beta or both. The mRNA expression was examined using real-time polymerase chain reaction, and the concentration of total soluble collagen in conditioned media was analysed by Sircol Collagen Assay. In addition, the protein expressions of androgen receptor, CTGF/CCN2 and type I collagen in gingival tissue were determined by western blot.

RESULTS

Interleukin-1 beta was more potent than nifedipine in stimulating CTGF/CCN2 and procollagen alpha1(I) mRNA expression, and there was an additive effect of the two drugs. Healthy cells exhibited an equal or stronger response of procollagen alpha1(I) than those with DIGO, but DIGO cells displayed a stronger response in the secretion of soluble collagen in the same conditions. Flutamide, an androgen receptor antagonist, inhibited stimulation by nifedipine or interleukin-1 beta. Additionally, the protein expressions of androgen receptor and type I collagen were higher in DIGO gingival tissue than those in healthy gingival tissue.

CONCLUSION

The data suggest that both nifedipine and interleukin-1 beta play an important role in DIGO via androgen receptor upregulation and that gingival overgrowth is mainly due to collagen accumulation. Flutamide decreases the gene expression and protein production of collagen from dihydropyridine-induced overgrowth cells.

Neuraminidase-1 is required for the normal assembly of elastic fibers

The assembly of elastic fibers in tissues that undergo repeated cycles of extension and recoil, such as the lungs and blood vessels, is dependent on the proper interaction and alignment of tropoelastin with a microfibrillar scaffold. Here, we describe in vivo histopathological effects of neuraminidase-1 (Neu1) deficiency on elastin assembly in the lungs and aorta of mice. These mice exhibited a tight-skin phenotype very similar to the Tsk mouse. Normal septation of Neu1-null mice did not occur in neonatal mice, resulting in enlarged alveoli that were maintained in adults. The abnormal development of elastic fibers was remarkable under electron microscopy and confirmed by the overlapping distribution of elastin, fibrillin-1, fibrillin-2, and fibulin-5 (Fib-5) by the light microscopy immunostainings. Fib-5 fibers appeared diffuse and unorganized around the alveolar walls and the apex of developing secondary septal crests. Fibrillin-2 deposition was also abnormal in neonatal and adult lungs. Dispersion of myofibroblasts appeared abnormal in developing lungs of Neu1-null mice, with a random distribution of myofibroblast around the alveolar walls, rather than concentrating at sites of elastin synthesis. The elastic lamellae in the aorta of the Neu1-null mice were thinner and separated by hypertrophic smooth muscle cells that were surrounded by an excess of the sialic acid-containing moieties. The concentration of elastin, as measure by desmosine levels, was significantly reduced in the aorta of Neu1-null mice. Message levels for tropoelastin and Fib-5 were normal, suggesting the elastic fiber defects in Neu1-null mice result from impaired extracellular assembly.

Pharmacological blockade of A2A receptors prevents dermal fibrosis in a model of elevated tissue adenosine

Adenosine is a potent modulator of inflammation and tissue repair. We have recently reported that activation of adenosine A(2A) receptors promotes collagen synthesis by human dermal fibroblasts and that blockade or deletion of this receptor in mice protects against bleomycin-induced dermal fibrosis, a murine model of scleroderma. Adenosine deaminase (ADA) is the principal catabolic enzyme for adenosine in vivo, and its deficiency leads to the spontaneous development of pulmonary fibrosis in mice. The aim of this study was to characterize further the contributions of endogenous adenosine and adenosine A(2A) receptors to skin fibrosis. Taking advantage of genetically modified ADA-deficient mice, we herein report a direct fibrogenic effect of adenosine on the skin, in which increased collagen deposition is accompanied by increased levels of key mediators of fibrosis, including transforming growth factor beta1, connective tissue growth factor, and interleukin-13. Pharmacological treatment of ADA-deficient mice with the A(2A) receptor antagonist ZM-241385 prevented the development of dermal fibrosis in this model of elevated tissue adenosine, by reducing dermal collagen content and expression of profibrotic cytokines and growth factors. These data confirm a fibrogenic role for adenosine in the skin and reveal A(2A) receptor antagonists as novel therapeutic agents for the modulation of dermal fibrotic disorders.

The anatomy of the cremaster muscle during inguinoscrotal testicular descent in the rat

BACKGROUND

Extrapolation of rat testicular descent studies to humans has been criticized because of anatomical differences of the cremaster muscle. Human cremaster is described as a thin strip rather than a large, complete sac as in rats, which is proposed to be more important in propelling the testis during descent. This study investigated cremaster muscle anatomy and ontogeny in both normal and cryptorchid rat models.

METHODS

Gubernacula from 4 groups of neonatal rats were sectioned longitudinally and transversely: normal Sprague-Dawley, capsaicin pretreated, flutamide pretreated, and congenital cryptorchid rats. Gubernacula were stained with hematoxylin-eosin, Masson trichrome, and desmin immunohistochemistry to study muscle development.

RESULTS

Myoblasts are more numerous at the gubernacular tip, whereas the most differentiated muscle is proximal. Rat cremaster develops as an elongated strip rather than a complete sac derived from abdominal wall muscles. Flutamide and capsaicin pretreatment disrupts development.

CONCLUSION

Rat cremaster muscle develops as a strip, bearing close resemblance to human cremaster muscle, permitting extrapolation of cremaster function to human testicular descent. The cremaster muscle appears to differentiate from the gubernacular tip during elongation to the scrotum, and requires intact sensory innervation and androgen.

Distinct effects of gonadectomy in male and female mice on collagen fibrillogenesis in the skin

BACKGROUND

Collagen biosynthesis and deposition is a complex, multistep process, which is tightly regulated to maintain proper tissue homeostasis. Sex steroid hormones have been implicated in regulating collagen synthesis; however the specific mechanisms regulating the process remain largely unknown.

OBJECTIVE

To investigate the role of estrogens and androgens in the regulation of genes involved in collagen synthesis and fibrillogenesis using gonadectomized C57/B6 mice.

METHODS

Collagen content was assessed by hydroxyproline measurement and acetic acid extraction of collagen with or without the addition of pepsin. The mRNA levels of fibrillar collagens and enzymes involved in fibrillogenesis were determined by QPCR analysis. The protein expression of decorin, lumican and fibromodulin was confirmed by immunostaining.

RESULTS

We have shown that castration resulted in a markedly decreased skin thickness and collagen content without affecting collagen solubility. Furthermore, the mRNA levels of fibrillar collagen genes including types I, III, and V were decreased, suggesting that androgens positively regulate the rate of collagen gene transcription. Conversely, ovariectomy mainly affected collagen solubility. The absence of estrogens resulted in decreased expression levels of several of the small leucine-rich repeat proteins and proteoglycans (SLRPs) including decorin, fibromodulin and lumican.

CONCLUSIONS

Estrogens may not be directly involved in the regulation of collagen synthesis; however, they may play a critical role in regulating organization and stability of collagen fibrils. Androgens play a positive role in the regulation of collagen biosynthesis. In summary, our data demonstrate that androgens and estrogens regulate distinct aspects of collagen fibrillogenesis in mouse skin.

The impact of sex and sex hormones on lung physiology and disease: lessons from animal studies

Numerous animal studies have revealed significant effects of sex and sex hormones on normal lung development, lung physiology, and various lung diseases. The primary goal of this review is to summarize knowledge to date on the effects of sex and sex hormones on lung development, physiology, and disease in animals. Specific emphasis will be placed on fibrosis, allergic airway disease, acute lung injury models, respiratory infection, and lung toxicology studies.

Adenosine A2A receptors in diffuse dermal fibrosis: pathogenic role in human dermal fibroblasts and in a murine model of scleroderma

OBJECTIVE

Adenosine regulates inflammation and tissue repair, and adenosine A2A receptors promote wound healing by stimulating collagen matrix production. We therefore examined whether adenosine A2A receptors contribute to the pathogenesis of dermal fibrosis.

METHODS

Collagen production by primary human dermal fibroblasts was analyzed by real-time polymerase chain reaction, 14C-proline incorporation, and Sircol assay. Intracellular signaling for dermal collagen production was investigated using inhibitors of MEK-1 and by demonstration of ERK phosphorylation. In vivo effects were studied in a bleomycin-induced dermal fibrosis model using adenosine A2A receptor-deficient wild-type littermate mice, C57BL/6 mice, and mice treated with adenosine A2A receptor antagonist. Morphometric features and levels of hydroxyproline were determined as measures of dermal fibrosis.

RESULTS

Adenosine A2A receptor occupancy promoted collagen production by primary human dermal fibroblasts, which was blocked by adenosine A2A, but not A1 or A2B, receptor antagonism. Adenosine A2A receptor ligation stimulated ERK phosphorylation, and A2A receptor-mediated collagen production by dermal fibroblasts was blocked by MEK-1 inhibitors. Adenosine A2A receptor-deficient and A2A receptor antagonist-treated mice were protected from developing bleomycin-induced dermal fibrosis.

CONCLUSION

These results demonstrate that adenosine A2A receptors play an active role in the pathogenesis of dermal fibrosis and suggest a novel therapeutic target in the treatment and prevention of dermal fibrosis in diseases such as scleroderma.

Determining mechanical properties of rabbit skin with light reflection technique verified with latex

An experimental technique to evaluate the elastic limit for rabbit skin is developed and described. The experimental technique is designed to measure small changes in the normalized reflectivity as a function of applied stretch, with a laser wavelength of 632.8 nm and power of 1 mW. When the samples of rabbit skin are stretched, the reflectivity increases until a critical point (elastic limit) is reached. After this point, the curve drops off very quickly. The elastic limit for the male dorsal samples is less than that for the female samples, with an average strain of 14.4 and 34.6% in males and females, respectively. Moreover, our results show that the average slope of the regression lines is greater for the male dorsal samples than the dorsal female samples. This indicates that the male dorsal skin is rougher than that of the female.

Perifollicular Fibrosis: Pathogenetic Role in Androgenetic Alopecia

Androgenetic alopecia (AGA) is a dihydrotestosterone (DHT)-mediated process, characterized by continuous miniaturization of androgen reactive hair follicles and accompanied by perifollicular fibrosis of follicular units in histological examination. Testosterone (T: 10(-9)-10(-7) M) treatment increased the expression of type I procollagen at mRNA and protein level. Pretreatment of finasteride (10(-8) M) inhibited the T-induced type I procollagen expression at mRNA (40.2%) and protein levels (24.9%). T treatment increased the expression of transforming growth factor-beta 1 (TGF-beta1) at protein levels by 81.9% in the human scalp dermal fibroblasts (DFs). Pretreatment of finasteride decreased the expression of TGF-beta1 protein induced by an average of T (30.4%). The type I procollagen expression after pretreatment of neutralizing TGF-beta1 antibody (10 microg/ml) was inhibited by an average of 54.3%. Our findings suggest that T-induced TGF-beta1 and type I procollagen expression may contribute to the development of perifollicular fibrosis in the AGA, and the inhibitory effects on T-induced procollagen and TGF-beta1 expression may explain another possible mechanism how finasteride works in AGA.

Analysis of the tight skin (Tsk1/+) mouse as a model for testing antifibrotic agents

The tight skin 1 (B6.CgFbn1(Tsk)+/+Pldn(pa)/J, henceforth referred to as Tsk1/+) mouse was first described as a spontaneously occurring mutant that resulted in hyperplasia of the subcutaneous loose connective tissue, and has subsequently been proposed to be a model of the human fibrotic disorder scleroderma. We have investigated the Tsk1/+ mouse as a model system for testing the efficacy of antifibrotic agents against skin fibrosis. We find that the tightness of the skin at the scruff of the neck leads to a measurably thicker skin pinch, but we suggest that this is due to hyperplasia of the subdermal loose connective tissue, which results in increased tethering of the skin to the underlying muscle layers. In contrast to previously published data, we do not find a significant difference in the dermal thickness or collagen content of the Tsk1/+ mouse skin compared with wild-type controls. In addition, expression profiling of Tsk1/+ mouse skin indicated that there are very few changes in gene expression, and that there is no evidence for upregulation of the transforming growth factor beta signaling axis. Therefore, we conclude that this model is not suitable for testing the effect of antifibrotic agents on the dermis, and that changes potentially related to scleroderma may be confined to subdermal connective tissue.