Retinoic Acid Upregulates the Plasminogen Activator System in Human Epidermal Keratinocytes

Unveiling the potential effects of acetylsalicylic acid: insights into regeneration in endometrial stem cells

BACKGROUND

Although acetylsalicylic acid has been widely used for decades to treat and prevent various diseases, its potential effects on endometrial receptivity and subsequent pregnancy rates are still controversial due to conflicting data: many reports have shown positive effects of acetylsalicylic acid, whereas others have found that it has no effect. Furthermore, the direct effects of acetylsalicylic acid on various functions of normal endometrial cells, especially endometrial stem cells, and their underlying molecular mechanisms have not yet been proven. Recently, studies have revealed that a reduced number of active stem/progenitor cells within endometrial tissue limits cyclic endometrial regeneration and subsequently decreases pregnancy success rates, suggesting that endometrial stem cells play a critical role in endometrial regeneration and subsequent endometrial receptivity.

METHODS

We assessed whether aspirin treatment can inhibit various endometrial stem cell functions related to regenerative capacity, such as self-renewal, migration, pluripotency/stemness, and differentiation capacity, in vitro. Next, we evaluated whether SERPINB2 regulates the effects of aspirin on endometrial stem cell functions by depleting SERPINB2 expression with specific shRNA targeting SERPINB2. To further investigate whether aspirin also inhibits various endometrial stem cell functions in vivo, aspirin was administered daily to mice through intraperitoneal (i.p.) injection for 7 days.

RESULTS

In addition to its previously identified roles, to the best of our knowledge, we found for the first time that acetylsalicylic acid directly inhibits various human endometrial stem cell functions related to regenerative capacity (i.e., self-renewal, migration, differentiation, and capacity) through its novel target gene SERPINB2 in vitro. Acetylsalicylic acid exerts its function by suppressing well-known prosurvival pathways, such as Akt and/or ERK1/2 signaling, through a SERPINB2 signaling cascade. Moreover, we also found that acetylsalicylic acid markedly inhibits regenerative capacity-related functions in endometrial stem cells within tissue.

CONCLUSIONS

We have found that acetylsalicylic acid has diverse effects on various endometrial stem cell functions related to regenerative capacity. Our findings are a critical step toward the development of more effective therapeutic strategies to increase the chances of successful pregnancy. Video Abstract.

The Use of Retinoids for the Prevention and Treatment of Skin Cancers: An Updated Review

Retinoids are natural and synthetic vitamin A derivatives that are effective for the prevention and the treatment of non-melanoma skin cancers (NMSC). NMSCs constitute a heterogenous group of non-melanocyte-derived skin cancers that impose substantial burdens on patients and healthcare systems. They include entities such as basal cell carcinoma and cutaneous squamous cell carcinoma (collectively called keratinocyte carcinomas), cutaneous lymphomas and Kaposi’s sarcoma among others. The retinoid signaling pathway plays influential roles in skin physiology and pathology. These compounds regulate diverse biological processes within the skin, including proliferation, differentiation, angiogenesis and immune regulation. Collectively, retinoids can suppress skin carcinogenesis. Both topical and systemic retinoids have been investigated in clinical trials as NMSC prophylactics and treatments. Desirable efficacy and tolerability in clinical trials have prompted health regulatory bodies to approve the use of retinoids for NMSC management. Acceptable off-label uses of these compounds as drugs for skin cancers are also described. This review is a comprehensive outline on the biochemistry of retinoids, their activities in the skin, their effects on cancer cells and their adoption in clinical practice.

Therapeutic wavelengths of ultraviolet B radiation activate apoptotic, circadian rhythm, redox signalling and key canonical pathways in psoriatic epidermis

Ultraviolet B radiation (UVB) exerts pleiotropic effects on human skin. DNA damage response and repair pathways are activated by UVB; if damage cannot be repaired, apoptosis ensues. Although cumulative UVB exposure predisposes to skin cancer, UVB phototherapy is widely used as an effective treatment for psoriasis. Previous studies defined the therapeutic action spectrum of UVB and showed that psoriasis is resistant to apoptosis. This study aimed to investigate early molecular responses within psoriasis plaques following irradiation with single equi-erythemogenic doses of clinically-effective (311 nm, narrow-band) compared to clinically-ineffective (290 nm) UVB. Forty-eight micro-dissected epidermal samples from 20 psoriatic patients were analyzed using microarrays. Our bioinformatic analysis compared gene expression between 311 nm irradiated, 290 nm irradiated and control psoriasis epidermis to specifically identify 311 nm UVB differentially expressed genes (DEGs) and their upstream regulatory pathways. Key DEGs and pathways were validated by immunohistochemical analysis. There was a dynamic induction and repression of 311 nm UVB DEGs between 6 h and 18 h, only a limited number of DEGs maintained their designated expression status between time-points. Key disease and function pathways included apoptosis, cell death, cell migration and leucocyte chemotaxis. DNA damage response pathways, NRF2-mediated oxidative stress response and P53 signalling were key nodes, interconnecting apoptosis and cell cycle arrest. Interferon signalling, dendritic cell maturation, granulocyte adhesion and atherosclerotic pathways were also differentially regulated. Consistent with these findings, top transcriptional regulators of 311 nm UVB DEGs related to: a) apoptosis, DNA damage response and cell cycle control; b) innate/acquired immune regulation and inflammation; c) hypoxia/redox response and angiogenesis; d) circadian rhythmicity; f) EGR/AP1 signalling and keratinocyte differentiation; and g) mitochondrial biogenesis. This research provides important insights into the molecular targets of 311 nm UVB, underscoring key roles for apoptosis and cell death. These and the other key pathways delineated may be central to the therapeutic effects of 311 nm in psoriasis.

Novel technique for the simultaneous isolation of cardiac fibroblasts and epicardial stromal cells from the infarcted murine heart

AIMS

Myocardial infarction (MI) leads to activation of cardiac fibroblasts (aCFs) and at the same time induces the formation of epicardium-derived cells at the heart surface. To discriminate between the two cell populations, we elaborated a fast and efficient protocol for the simultaneous isolation and characterization of aCFs and epicardial stromal cells (EpiSCs) from the infarcted mouse heart.

METHODS AND RESULTS

For the isolation of aCFs and EpiSCs, infarcted hearts (50 min ischaemia/reperfusion) were digested by perfusion with a collagenase-containing medium for only 8 min, while EpiSCs were enzymatically removed from the outside by applying mild shear forces via a motor driven device. Cardiac fibroblasts (CFs) isolated from unstressed hearts served as control. Viability of isolated cells was >90%. Purity of EpiSCs was confirmed by immunofluorescence staining and qPCR of various mesenchymal markers including Wilms-tumor-protein-1. Microarray analysis of CFs, aCFs, and EpiSCs on day 5 post-MI revealed a unique gene expression pattern in the EpiSC fraction, which was enriched for epithelial markers and epithelial to mesenchymal transition-related genes. Compared to aCFs, 336 significantly altered gene entities were identified in the EpiSC fraction. qPCR analysis showed high expression of Serpinb2, Cxcl13, Adora2b, and Il10 in EpiSCs relative to CFs and aCFs. Furthermore, microarray data identified Ddah1 and Cemip to be highly up-regulated in aCFs compared to CFs. Immunostaining of the infarcted heart revealed a unique distribution of Dermokine, Aquaporin-1, Cytokeratin, Lipocalin2, and Periostin within the epicardial cell layer.

CONCLUSIONS

We describe the simultaneous isolation of viable, purified fractions of aCFs and EpiSCs from the infarcted mouse heart. In this study, several differentially expressed markers for aCFs and EpiSCs were identified, underlining the importance of cell separation to study heterogeneity of stromal cells in the healing process after MI.

An Endogenous Anti-aging Factor, Sonic Hedgehog, Suppresses Endometrial Stem Cell Aging through SERPINB2

Endometrial stem cells are located in the basal layer of the endometrium, and they are responsible for the cyclic regeneration of the uterus during the menstrual cycle. Recent studies have revealed that recurrent pregnancy loss is associated with an age-related stem cell deficiency in the endometrium. Therefore, intensive study of endometrial stem cell aging may provide new insights for preventing recurrent pregnancy loss. Sonic hedgehog (SHH) signaling has been identified as a morphogen during the embryonic development processes. In addition to this canonical function, we found that the age-associated decline in regenerative potential in the endometrium may be due to decreased SHH-signaling integrity in local stem cells with aging. Importantly, the current study also showed that SHH activity clearly declines with aging both in vitro and in vivo, and exogenous SHH treatment significantly alleviates various aging-associated declines in multiple endometrial stem cell functions, suggesting that SHH may act as an endogenous anti-aging factor in human endometrial stem cells. Moreover, we found that stem cell senescence may enhance SERPINB2 expression, which in turn mediates the effect of SHH on alleviating senescence-induced endometrial stem cell dysfunctions, suggesting that SERPINB2 is a master regulator of SHH signaling during the aging process.

SERPINB2 is a novel indicator of stem cell toxicity

The toxicological evaluation of potential drug candidates is very important in the preclinical phase of drug development. Toxic materials may cause serious decline in stem cell function and loss of stemness. Indeed, we found that toxic exposure more profoundly suppressed the growth of stem cells than terminally differentiated fibroblasts. Importantly, toxic exposure suppressed stem cell migration and multi-lineage differentiation potential in vitro and in vivo. Moreover, early-response genes involved in stem cell properties such as self-renewal and differentiation capabilities can be used as specific markers to predict toxicity. In the present study, we also identified a labile toxic response gene, SERPINB2, which is significantly increased in response to various toxic agents in human stem cells in vitro and in vivo. Consistently, self-renewal, migration, and multi-lineage differentiation potential were markedly decreased following SERPINB2 overexpression. To the best of our knowledge, this is the first study to focus on the functions of SERPINB2 on the regenerative potential of stem cells in response to various existing chemicals, and the findings will facilitate the development of promising toxicity test platforms for newly developed chemicals.

SerpinB2 Deficiency Results in a Stratum Corneum Defect and Increased Sensitivity to Topically Applied Inflammatory Agents

SerpinB2 (plasminogen activator inhibitor type 2) is constitutively expressed at high levels by differentiating keratinocytes in mice and humans; however, the physiological function of keratinocyte SerpinB2 remains unclear. Herein, we show that SerpinB2(-/-) mice are more susceptible to contact dermatitis after topical application of dinitrofluorobenzene, and show enhanced inflammatory lesions after topical applications of phorbol ester. Untreated SerpinB2(-/-) mice showed no overt changes in epithelial structure, and we were unable to find evidence for a role for keratinocyte SerpinB2 in regulating immunity, apoptosis, IL-1β production, proteasomal activity, or wound healing. Instead, the phenotype was associated with impaired skin barrier function and a defective stratum corneum, with SerpinB2(-/-) mice showing increased transepidermal water loss, increased overt loss of stratum corneum in inflammatory lesions, and impaired stratum corneum thickening after phorbol ester treatment. Immunoblotting suggested that SerpinB2 (cross-linked into the cornified envelope) is present in the stratum corneum and retains the ability to form covalent inhibitory complexes with urokinase. Data suggest that the function of keratinocyte SerpinB2 is protection of the stratum corneum from proteolysis via inhibition of urokinase, thereby maintaining the integrity and barrier function of the stratum corneum, particularly during times of skin inflammation. Implications for studies involving genetically modified mice treated with topical agents and human dermatological conditions, such as contact dermatitis, are discussed.

The role of nuclear hormone receptors in cutaneous wound repair

The cutaneous wound repair process involves balancing a dynamic series of events ranging from inflammation, oxidative stress, cell migration, proliferation, survival and differentiation. A complex series of secreted trophic factors, cytokines, surface and intracellular proteins are expressed in a temporospatial manner to restore skin integrity after wounding. Impaired initiation, maintenance or termination of the tissue repair processes can lead to perturbed healing, necrosis, fibrosis or even cancer. Nuclear hormone receptors (NHRs) in the cutaneous environment regulate tissue repair processes such as fibroplasia and angiogenesis. Defects in functional NHRs and their ligands are associated with the clinical phenotypes of chronic non-healing wounds and skin endocrine disorders. The functional relationship between NHRs and skin niche cells such as epidermal keratinocytes and dermal fibroblasts is pivotal for successful wound closure and permanent repair. The aim of this review is to delineate the cutaneous effects and cross-talk of various nuclear receptors upon injury towards functional tissue restoration.

Donor site healing dynamics: molecular, histological, and noninvasive imaging assessment in a porcine model

Understanding the physiology of donor site healing will lead to advances in how these wounds are treated and may ultimately allow faster healing, more frequent autografting, and more effective care of the burn-injured patient. Unfortunately, a paucity of data exists regarding perfusion metrics over the course of donor site healing. Furthermore, there are no studies that interrelate indices of perfusion with the molecular and cellular processes of donor site healing. Male Duroc pigs were anesthetized and donor site wounds were created using a Zimmer dermatome at a depth of 0.060 inch (1.52 mm). Digital photographs, laser Doppler images, and punch biopsies were obtained before and after excision and on days 2, 4, 7, 9, 11, 14, and 16 until wounds were healed. RNA isolation was performed and quantitative polymerase chain reaction was used to examine differential gene expression over the time course. Formalin-fixed biopsies were embedded in paraffin, sectioned, stained, and examined. Wound surfaces were 83% re-epithelialized by day 16. Perfusion peaked on day 2 then declined, but it remained significantly elevated compared to before excision (P < .05). From day 9 onward, mean perfusion units were not significantly different from baseline (P < .05). Twenty-two representative genes were selected for examination. RNA expression of collagen, tenascin-cytoactin, inflammatory cytokines, remodeling enzymes, growth factors, and Wnt was increased. Inflammatory cells and cytokines were demonstrated histologically. Nuclei per high powered field peaked at day 7 and neodermal thickness increased daily to day 14. A novel porcine model for donor site wound healing that interrelates re-epithelilaizationand perfusion with molecular and cellular indices has been demonstrated.

Loss of Arnt (Hif1β) in mouse epidermis triggers dermal angiogenesis, blood vessel dilation and clotting defects

Targeted ablation of Aryl hydrocarbon receptor nuclear translocator (Arnt) in the mouse epidermis results in severe abnormalities in dermal vasculature reminiscent of petechia induced in human skin by anticoagulants or certain genetic disorders. Lack of Arnt leads to downregulation of Egln3/Phd3 hydroxylase and concomitant hypoxia-independent stabilization of hypoxia-induced factor 1α (Hif1α) along with compensatory induction of Arnt2. Ectopic induction of Arnt2 results in its heterodimerization with stabilized Hif1α and is associated with activation of genes coding for secreted proteins implicated in control of angiogenesis, coagulation, vasodilation and blood vessel permeability such as S100a8/S100a9, S100a10, Serpine1, Defb3, Socs3, Cxcl1 and Thbd. Since ARNT and ARNT2 heterodimers with HIF1α are known to have different (yet overlapping) downstream targets our findings suggest that loss of Arnt in the epidermis activates an aberrant paracrine regulatory pathway responsible for dermal vascular phenotype in K14-Arnt KO mice. This assumption is supported by a significant decline of von Willebrand factor in dermal vasculature of these mice where Arnt level remains normal. Given the essential role of ARNT in the adaptive response to environmental stress and striking similarity between skin vascular phenotype in K14-Arnt KO mice and specific vascular features of tumour stroma and psoriatic skin, we believe that further characterization of Arnt-dependent epidermal-dermal signalling may provide insight into the role of macro- and micro-environmental factors in control of skin vasculature and in pathogenesis of environmentally modulated skin disorders.

Human papilloma virus transformed CaSki cells constitutively express high levels of functional SerpinB2

Many malignant tissues, including human papilloma virus (HPV)-associated cancers, express SerpinB2, also known as plasminogen activator inhibitor type-2 (PAI-2). Whether SerpinB2 is expressed by the HPV-transformed cancer cells, and if so, whether SerpinB2 is mutated or behaves aberrantly remains unclear. Here we show that HPV-transformed CaSki cells express high levels of constitutive wild-type SerpinB2, with cellular distribution, glycosylation, secretion, cleavage, induction and urokinase binding similar to that reported for primary cells. Neutralization of secreted SerpinB2 failed to affect CaSki cell migration or growth. Lentivirus-based over-expression of SerpinB2 also had no effect on growth, and we were unable to confirm a role for SerpinB2 in binding or regulating expression of the retinoblastoma protein. CaSki cells thus emerge as a useful tool for studying SerpinB2, with the physiological function of SerpinB2 expression by tumor cells remaining controversial. Using CaSki cells as a source of endogenous SerpinB2, we confirmed that SerpinB2 efficiently binds the proteasomal subunit member β1.

Increasing tPA activity in astrocytes induced by multipotent mesenchymal stromal cells facilitate neurite outgrowth after stroke in the mouse

We demonstrate that tissue plasminogen activator (tPA) and its inhibitors contribute to neurite outgrowth in the central nervous system (CNS) after treatment of stroke with multipotent mesenchymal stromal cells (MSCs). In vivo, administration of MSCs to mice subjected to middle cerebral artery occlusion (MCAo) significantly increased activation of tPA and downregulated PAI-1 levels in the ischemic boundary zone (IBZ) compared with control PBS treated mice, concurrently with increases of myelinated axons and synaptophysin. In vitro, MSCs significantly increased tPA levels and concomitantly reduced plasminogen activator inhibitor 1 (PAI-1) expression in astrocytes under normal and oxygen and glucose deprivation (OGD) conditions. ELISA analysis of conditioned medium revealed that MSCs stimulated astrocytes to secrete tPA. When primary cortical neurons were cultured in the conditioned medium from MSC co-cultured astrocytes, these neurons exhibited a significant increase in neurite outgrowth compared to conditioned medium from astrocytes alone. Blockage of tPA with a neutralizing antibody or knock-down of tPA with siRNA significantly attenuated the effect of the conditioned medium on neurite outgrowth. Addition of recombinant human tPA into cortical neuronal cultures also substantially enhanced neurite outgrowth. Collectively, these in vivo and in vitro data suggest that the MSC mediated increased activation of tPA in astrocytes promotes neurite outgrowth after stroke.

Identification of transcriptional regulatory cascades in retinoic acid-induced growth arrest of HepG2 cells

All-trans retinoic acid (ATRA) is a potent inducer of cell differentiation and growth arrest. Here, we investigated ATRA-induced regulatory cascades associated with growth arrest of the human hepatoma cell line HepG2. ATRA induced >2-fold changes in the expression of 402 genes including 55 linked to cell-cycle regulation, cell growth or apoptosis during 48 h treatment. Computational search predicted that 250 transcriptional regulatory factors (TRFs) could recognize the proximal upstream regions of any of the 55 genes. Expression of 61 TRF genes was significantly changed during ATRA incubation, providing many potential regulatory edges. We focused on six TRFs that could regulate many of the 55 genes and found a total of 160 potential edges in which the expression of each of the genes was changed later than the expression change of the corresponding regulator. RNAi knockdown of the selected TRFs caused perturbation of the respective potential targets. The genes showed an opposite regulation pattern by ATRA and specific siRNA treatments were selected as strong candidates for direct TRF targets. Finally, 36 transcriptional regulatory edges were validated by chromatin immunoprecipitation. These analyses enabled us to depict a part of the transcriptional regulatory cascades closely linked to ATRA-induced cell growth arrest.

Physiological Role of Retinyl Palmitate in the Skin

The skin is similar to other organs in how it absorbs, stores, and metabolizes vitamin A. However, because of the anatomical location of skin and the specialized physiological roles it plays, there are ways in which the skin is rather unique. The stratified structure of the epidermis results from the orchestration of retinoid-influenced cellular division and differentiation. Similarly, many of the physiological responses of the skin, such as dermal aging, immune defense, and wound healing, are significantly affected by retinoids. While much is known about the molecular events through which retinoids affect the skin's responses, more remains to be learned. Interest in the effects of retinol, retinyl palmitate, and other retinoids on the skin, fueled in part by the promise of improved dermatologic and cosmetic products, will undoubtedly make the effects of retinoids on skin a subject for continued intense investigation.

Effects of brief cutaneous JP-8 jet fuel exposures on time course of gene expression in the epidermis

The jet fuel jet propulsion fuel 8 (JP-8) has been shown to cause an inflammatory response in the skin, which is characterized histologically by erythema, edema, and hyperplasia. Studies in laboratory animal skin and cultured keratinocytes have identified a variety of changes in protein levels related to inflammation, oxidative damage, apoptosis, and cellular growth. Most of these studies have focused on prolonged exposures and subsequent effects. In an attempt to understand the earliest responses of the skin to JP-8, we have investigated changes in gene expression in the epidermis for up to 8 h after a 1-h cutaneous exposure in rats. After exposure, we separated the epidermis from the rest of the skin with a cryotome and isolated total mRNA. Gene expression was studied with microarray techniques, and changes from sham treatments were analyzed and characterized. We found consistent twofold increases in gene expression of 27 transcripts at 1, 4, and 8 h after the beginning of the 1-h exposure that were related primarily to structural proteins, cell signaling, inflammatory mediators, growth factors, and enzymes. Analysis of pathways changed showed that several signaling pathways were increased at 1 h and that the most significant changes at 8 h were in metabolic pathways, many of which were downregulated. These results confirm and expand many of the previous molecular studies with JP-8. Based on the 1-h changes in gene expression, we hypothesize that the trigger of the JP-8-induced, epidermal stress response is a physical disruption of osmotic, oxidative, and membrane stability which activates gene expression in the signaling pathways and results in the inflammatory, apoptotic, and growth responses that have been previously identified.

Retinoic Acid and its 4-Oxo Metabolites are Functionally Active in Human Skin Cells In Vitro

Retinoic acid exerts a variety of effects on gene transcription that regulate growth, differentiation, and inflammation in normal and neoplastic skin cells. Because there is a lack of information regarding the influence of metabolic transformation of retinoids on their pharmacologic effects in skin, we have analyzed the functional activity of all-trans-, 9-cis-, and 13-cis-retinoic acid and their 4-oxo-metabolites in normal human epidermal keratinocytes (NHEKs) and dermal fibroblasts using gene and protein expression profiling techniques, including cDNA microarrays, two-dimensional gel electrophoresis, and MALDI-MS. It was previously thought that the 4-oxo-metabolites of RA are inert catabolic end-products but our results indicate instead that they display strong and isomer-specific transcriptional regulatory activity in both NHEKs and dermal fibroblasts. Microarray and proteomic analyses identified a number of novel genes/gene products that are influenced by RA treatment of NHEKs or fibroblasts, including genes for enzymes catalyzing biotransformation of retinoids, corticosteroids, and antioxidants and structural and transport proteins known to be essential for homeostasis. Our results expand current knowledge regarding retinoic acid action within skin cells and the target tissue/cell regulatory systems that are important for modulating the physiological and pharmacological effects of this important class of dermatological drugs.

Effects of drugs and anticytokine antibodies on expression of ATP2A2 and ATP2C1 in cultured normal human keratinocytes

BACKGROUND

Darier's disease (DD) and Hailey-Hailey disease (HHD) are skin disorders arising, respectively, from autosomal dominant mutations in ATP2A2, encoding the sacro/endoplasmic reticulum calcium ATPase, and ATP2C1, encoding the Golgi apparatus calcium ATPase. Exposure to ultraviolet (UV) B irradiation exacerbates the skin lesions, which can be treated with corticosteroids and retinoids.

OBJECTIVES

To investigate the molecular basis for DD and HHD.

METHODS

We used quantitative reverse transcriptase-polymerase chain reactions to examine the effects of UVB irradiation on ATP2A2 and ATP2C1 mRNA levels in cultured normal keratinocytes.

RESULTS

We observed that UVB irradiation reduced ATP2A2 and ATP2C mRNA levels. The addition of retinoids or corticosteroids to the cell culture inhibited the UVB-induced suppression of both ATP2A2 and ATP2C1 mRNA levels, and UVB-induced suppression of ATP2C1 mRNA was also inhibited by the addition of ciclosporin, tacrolimus and vitamin D(3). The addition of anti-interleukin (IL)-6 antibody to the cell culture prevented the UVB-induced suppression of ATP2A2 and ATP2C1 mRNA; in contrast, the addition of anti-IL-8 antibody slightly accelerated the suppression.

CONCLUSIONS

These results suggest that drugs effective for DD and HHD act by modulating ATP2A2 and ATP2C1 mRNA expression, respectively, and that the proinflammatory cytokines IL-6 and IL-8 play important roles in the regulation of ATPA2 and ATP2C1 expression in homeostasis and/or inflammation of the skin.

Factors that affect equine wound repair

The rate and outcome of wound healing are determined by many factors,some of which are already in effect when the horse is first presented to the veterinarian. A thorough understanding of wound healing principles,coupled with clear client communication, should enable the practitioner to minimize the number of additional factors that may exacerbate the initial situation.

The effect of topical tretinoin on tissue strength and skin components in a murine incisional wound model

BACKGROUND

Vitamin A derivatives modulate the inflammatory phase in wound healing. Retinoic acid can restore decreased tensile strength and collagen content in steroid- or diabetes-impaired wounds. It is hypothesized that retinoic acid can lead to accelerated healing with improved breaking strength in unimpaired incisional wounds.

MATERIALS AND METHODS

Skin incisions were made in 45 CD-1 mice. The sutured wounds were treated once daily with topical all-trans-retinoic acid 0.1% (n = 15), vehicle ointment (n = 15), or left untreated (n = 15). Skin biopsies at 1-, 2-, and 3-week intervals were examined using hematoxylin and eosin (H&E), Masson's trichrome, and immunoperoxidase staining methods. Wound breaking strength was determined by biomechanical analysis.

RESULTS

Incisions treated with retinoic acid exhibited a significantly reduced breaking strength at week 1 when compared to the vehicle and control group. Histologic examination showed a prolonged inflammatory reaction with abundant deposition of granulation tissue. Despite an increased fibroplastic proliferation in the tretinoin-treated wounds, the production of collagen was diminished.

CONCLUSIONS

Topical retinoic acid does not enhance the healing of unimpaired incisional wounds. The inadequate tensile strength in the early phase of the healing process is possibly the result of an increased dermal inflammatory response and the decreased collagen content. Although these adverse effects disappeared by 3 weeks postwounding, we found no discernible benefit of supplemental retinoic acid in unimpaired wounds.

Inhibition of retinoblastoma protein degradation by interaction with the serpin plasminogen activator inhibitor 2 via a novel consensus motif

Plasminogen activator inhibitor-2 (PAI-2) is well documented as an inhibitor of the extracellular serine proteinase urokinase-type plasminogen activator (uPA) and is expressed in activated monocytes and macrophages, differentiating keratinocytes, and many tumors. Here we show that PAI-2 has a novel intracellular function as a retinoblastoma protein (Rb)-binding protein. PAI-2 colocalized with Rb in the nucleus and inhibited the turnover of Rb, which led to increases in Rb protein levels and Rb-mediated activities. Although PAI-2 contains an LXCXE motif, Rb binding was primarily mediated by the C-D interhelical region of PAI-2, which was found to bind to the C pocket of Rb. The C-D interhelical region of PAI-2 contained a novel Rb-binding motif, termed the PENF homology motif, which is shared by many cellular and viral Rb-binding proteins. PAI-2 expression also protected Rb from the accelerated degradation mediated by human papillomavirus (HPV) E7, leading to recovery of Rb and inhibition of E6/E7 mRNA expression. Protection of Rb by PAI-2 begins to explain many of the diverse, uPA-independent phenotypes conferred by PAI-2 expression. These results indicate that PAI-2 may enhance Rb's tumor suppressor activity and suggest a potential therapeutic role for PAI-2 against HPV-transformed lesions.

Malodorous fungating wounds: uncertain concepts underlying the management of social isolation

Malodorous fungating wounds can exacerbate the social isolation of patients with palliative care needs through changes in patients' body image. There is a lack of consensus regarding the most effective management approaches for patients with malodorous fungating wounds. This appears to relate to the existence of different theoretical frameworks for understanding altered body image. This article explores the theories used to create frameworks that have been used for interventions with patients experiencing social isolation arising from altered body image. It argues that there is a need for health care professionals to appreciate the lack of consensus within the literature and to understand this in the context of the relationship between theory and research. The author offers research and clinical recommendations.

Protease inhibitors prevent plasminogen-mediated, but not pemphigus vulgaris-induced, acantholysis in human epidermis

Pemphigus is an autoimmune blistering disease of the skin and mucous membranes. It is caused by autoantibodies directed against desmosomes, which are the principal adhesion structures between epidermal keratinocytes. Binding of autoantibodies leads to the destruction of desmosomes resulting in the loss of cell-cell adhesion (acantholysis) and epidermal blisters. The plasminogen activator system has been implicated as a proteolytic effector in pemphigus. We have tested inhibitors of the plasminogen activator system with regard to their potential to prevent pemphigus-induced cutaneous pathology. In a human split skin culture system, IgG preparations of sera from pemphigus vulgaris patients caused histopathologic changes (acantholysis) similar to those observed in the original pemphigus disease. All inhibitors that were tested (active site inhibitors directed against uPA, tPA, and/or plasmin; antibodies neutralizing the enzymatic activity of uPA or tPA; substances interfering with the binding of uPA to its specific cell surface receptor uPAR) failed to prevent pemphigus vulgaris IgG-mediated acantholysis. Plasminogen-mediated acantholysis, however, was effectively antagonized by the synthetic active site serine protease inhibitor WX-UK1 or by p-aminomethylbenzoic acid. Our data argue against applying anti-plasminogen activator/anti-plasmin strategies in the management of pemphigus.