Expression of prostaglandin E(2) receptor subtypes in mouse hair follicles

Metabolomics reveals metabolites associated with hair follicle cycle in cashmere goats

BACKGROUND

The hair follicle is a skin accessory organ that regulates hair development, and its activity varies on a regular basis. However, the significance of metabolites in the hair follicle cycle has long been unknown.

RESULTS

Targeted metabolomics was used in this investigation to reveal the expression patterns of 1903 metabolites in cashmere goat skin during anagen to telogen. A statistical analysis was used to investigate the potential associations between metabolites and the hair follicle cycle. The findings revealed clear changes in the expression patterns of metabolites at various phases and in various feeding models. The majority of metabolites (primarily amino acids, nucleotides, their metabolites, and lipids) showed downregulated expression from anagen (An) to telogen (Tn), which was associated with gene expression, protein synthesis and transport, and cell structure, which reflected, to some extent, that the cells associated with hair follicle development are active in An and apoptotic in An-Tn. It is worth mentioning that the expression of vitamin D3 and 3,3',5-triiodo-L-thyronine decreased and then increased, which may be related to the shorter and longer duration of outdoor light, which may stimulate the hair follicle to transition from An to catagen (Cn). In the comparison of different hair follicle development stages (An, Cn, and Tn) or feeding modes (grazing and barn feeding), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that common differentially expressed metabolites (DEMs) (2'-deoxyadenosine, L-valine, 2'-deoxyuridine, riboflavin, cytidine, deoxyguanosine, L-tryptophan, and guanosine-5'-monophosphate) were enriched in ABC transporters. This finding suggested that this pathway may be involved in the hair follicle cycle. Among these DEMs, riboflavin is absorbed from food, and the expression of riboflavin and sugars (D-glucose and glycogen) in skin tissue under grazing was greater and lower than that during barn feeding, respectively, suggesting that eating patterns may also alter the hair follicle cycle.

CONCLUSIONS

The expression patterns of metabolites such as sugars, lipids, amino acids, and nucleotides in skin tissue affect hair follicle growth, in which 2'-deoxyadenosine, L-valine, 2'-deoxyuridine, riboflavin, cytidine, deoxyguanosine, L-tryptophan, and guanosine-5'-monophosphate may regulate the hair follicle cycle by participating in ABC transporters. Feeding practices may regulate hair follicle cycles by influencing the amount of hormones and vitamins expressed in the skin of cashmere goats.

The Hair Growth-Promoting Effect of Gardenia florida Fruit Extract and Its Molecular Regulation

As a herbal medicine, the extract from the fruits of Gardenia florida has been widely used for its antioxidative, hypoglycemic, and anti-inflammatory properties. However, whether G. florida fruit extract (GFFE) regulates hair growth has been rarely studied. This study was the first application of GFFE on hair growth both in vitro (human dermal papilla cells, hDPCs) and in vivo (C57BL/6 mice). The effects of GFFE on cell proliferation and hair growth-associated gene expression in hDPCs were examined. Moreover, GFFE was applied topically on the hair-shaved skin of male C57BL/6 mice, the hair length was measured, and the skin histological profile was investigated. GFFE promoted the proliferation of hDPCs and significantly stimulated hair growth-promoting genes, including vascular endothelial growth factor (VEGF) and Wnt/β-catenin signals, but suppressed the expression of the hair loss-related gene transforming growth factor-β1 (TGF-β). Furthermore, GFFE treatment resulted in a significant increase in the number, size, and depth of cultured hair follicles and stimulated the growth of hair with local effects in mice. In summary, the results provided the preclinical data to support the much potential use of the natural product GFFE as a promising agent for hair growth.

Single-Cell Sequencing Reveals Differential Cell Types in Skin Tissues of Liaoning Cashmere Goats and Key Genes Related Potentially to the Fineness of Cashmere Fiber

Cashmere fineness is one of the important factors determining cashmere quality; however, our understanding of the regulation of cashmere fineness at the cellular level is limited. Here, we used single-cell RNA sequencing and computational models to identify 13 skin cell types in Liaoning cashmere goats. We also analyzed the molecular changes in the development process by cell trajectory analysis and revealed the maturation process in the gene expression profile in Liaoning cashmere goats. Weighted gene co-expression network analysis explored hub genes in cell clusters related to cashmere formation. Secondary hair follicle dermal papilla cells (SDPCs) play an important role in the growth and density of cashmere. ACTA2, a marker gene of SDPCs, was selected for immunofluorescence (IF) and Western blot (WB) verification. Our results indicate that ACTA2 is mainly expressed in SDPCs, and WB results show different expression levels. COL1A1 is a highly expressed gene in SDPCs, which was verified by IF and WB. We then selected CXCL8 of SDPCs to verify and prove the differential expression in the coarse and fine types of Liaoning cashmere goats. Therefore, the CXCL8 gene may regulate cashmere fineness. These genes may be involved in regulating the fineness of cashmere in goat SDPCs; our research provides new insights into the mechanism of cashmere growth and fineness regulation by cells.

Analysis of Bimatoprost-Induced changes on Rabbits eyelash Follicle: Clinical and Electron microscopic study

Objective

To analyze ultrastructural changes of rabbits' eyelash follicles treated with bimatoprost eye drops to increase our knowledge of how this drug works.

Methods

The study included 15 clinically healthy male rabbits. All rabbits were treated with bimatoprost 0.03% daily for 4 weeks with one drop of the topical eye drops applied to the conjunctival fornix of the right eyes; left eyes were used as controls. Eyelash lengths were measured before and after treatment. The eyelid of each animal was dissected for light and electron microscopic analysis.

Results

Both control and treated rabbit eyes matched regarding eyelash length before treatment (9.80±0.388mm vs 9.88±0.24mm) (P=0.108). There was a significant increase in eyelash length between control (9.75±0.33 mm) and treated rabbit eyes (11.60±0.46 mm) (P=0.369). Light and electron microscopy revealed, bimatoprost treated eyes had thick epidermis. The dermis contained two hairs growing out of the same hair follicle. Heavily keratinized Henle's layer, the cortical cells (Cx) have prominent nucleolus and cytoplasm is studded with melanin granules.

Conclusion

Bimatoprost-induced eyelash changes were not restricted to increased eyelash length, thickness, and pigmentation but also showed increased number of eyelashes within the same hair follicle which were stronger and could resist pulling from the skin without any evidence of inflammatory cells within the specimens. These changes occurred as early as 1 month of treatment, giving rise to thoughts about the possibility of using bimatoprost eye drops as a prophylaxis against madarosis associated with chemotherapy if it is started 1 month before chemotherapy and continued afterwards, making eyelashes stronger and resistant to falling out.

Synchronous profiling and analysis of mRNAs and ncRNAs in the dermal papilla cells from cashmere goats

Background

Dermal papilla cells (DPCs), the “signaling center” of hair follicle (HF), delicately master continual growth of hair in mammals including cashmere, the fine fiber annually produced by secondary HF embedded in cashmere goat skins. Such unparalleled capacity bases on their exquisite character in instructing the cellular activity of hair-forming keratinocytes via secreting numerous molecular signals. Past studies suggested microRNA (miRNAs) and long non-coding RNAs (lncRNAs) play essential roles in a wide variety of biological process, including HF cycling. However, their roles and related molecular mechanisms in modulating DPCs secretory activities are still poorly understood.

Results

Here, we separately cultivated DPCs and their functionally and morphologically distinct dermal fibroblasts (DFs) from cashmere goat skins at anagen. With the advantage of high throughput RNA-seq, we synchronously identified 2540 lncRNAs and 536 miRNAs from two types of cellular samples at 4th passages. Compared with DFs, 1286 mRNAs, 18 lncRNAs, and 42 miRNAs were upregulated, while 1254 mRNAs, 53 lncRNAs and 44 miRNAs were downregulated in DPCs. Through overlapping with mice data, we ultimately defined 25 core signatures of DPCs, including HOXC8 and RSPO1, two crucial activators for hair follicle stem cells (HFSCs). Subsequently, we emphatically investigated the impacts of miRNAs and lncRNAs (cis- and trans- acting) on the genes, indicating that ncRNAs extensively exert negative and positive effects on their expressions. Furthermore, we screened lncRNAs acting as competing endogenous RNAs (ceRNAs) to sponge miRNAs and relief their repressive effects on targeted genes, and constructed related lncRNAs-miRNAs-HOXC8/RSPO1 interactive lines using bioinformatic tools. As a result, XR_310320.3-chi-miR-144-5p-HOXC8, XR_311077.2-novel_624-RSPO1 and others lines appeared, displaying that lncRNAs might serve as ceRNAs to indirectly adjust HFSCs status in hair growth.

Conclusion

The present study provides an unprecedented inventory of lncRNAs, miRNAs and mRNAs in goat DPCs and DFs. We also exhibit some miRNAs and lncRNAs potentially participate in the modulation of HFSCs activation via delicately adjusting core signatures of DPCs. Our report shines new light on the latent roles and underlying molecular mechanisms of ncRNAs on hair growth.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5861-4) contains supplementary material, which is available to authorized users.

In Vivo Analysis of Prostaglandins-induced Ocular Surface and Periocular Adnexa Modifications in Patients with Glaucoma

BACKGROUND/AIM

Prostaglandin analogues (PGAs) are a first-line medical treatment for glaucoma because of their powerful intraocular pressure (IOP) lowering effect, few systemic side-effects (SEs), and the once daily administration. Despite the high systemic safety profile, the chronic use of PGAs may induce periocular and ocular surface (OS)-related side effects, which affect a significant proportion of glaucomatous patients. In this review, we summarize the current knowledge about SEs of PGAs on periocular structures and OS, and their implications in clinical practice.

MATERIALS AND METHODS

A comprehensive literature search on the PubMed platform was performed. Two hundred fifty articles fulfilling key words were identified, of which 180 were excluded since they did not concern the effects of PGAs on the periocular tissues and OS, or because of their limited relevance. The following key words were used and combined, to narrow-down the literature: "prostaglandin" and "ocular surface," which identified 184 unique publications, of which 68 were selected; "prostaglandin" and "periocular" which identified 46 unique publications, of which 11 were selected. An additional search was conducted using "prostaglandin" and "Meibomian glands (MGs)", which identified twenty unique publications, of which 8 were selected. Thus, a total of 70 articles were chosen based on their relevance and were included in this review.

RESULTS

Prostaglandin-associated peri-orbitopathy, skin pigmentation and hypertrichosis, eyelash growth, and MGs dysfunction are the most frequent modifications of periocular tissues. They are induced by the tissue accumulation of PGAs, and FP receptor stimulation. Without preservatives, PGAs act as stimulators of conjunctival goblet cells, which are the main source of ocular surface mucoproteins, and seem to increase conjunctival epithelium microcysts proposed as in vivo hallmark of the trans-scleral aqueous humour outflow. Additional PGA-induced modifications can be recognized in the cornea, corneo-scleral limbus, conjunctival stroma and, conjunctiva-associated lymphoid tissue, mainly appearing as inflammatory changes. OS epithelia desquamation, chemosis, apoptosis, dendritic cell activation, conjunctival or episcleral vasodilation, and sub-basal nerve plexus disruption were also described in patients receiving preserved PGAs.

CONCLUSION

PGAs induce several modifications of the OS structures and adnexa; nonetheless, none of them significantly reduces the local safety profile of this class of drugs. Moreover, the OS changes do not affect the IOP lowering efficacy of PGAs. On these bases, local SEs of PGAs should not discourage clinicians in using this class of medications because of their efficacy, the systemic safety profile, and the better adherence.

Therapeutic potential of bimatoprost for the treatment of eyebrow hypotrichosis

Eyebrows serve as a key feature of the face and have many roles, including cosmetic appearance and social communication. Eyebrow hypotrichosis, which refers to reduction or absence of the eyebrow hair, could be a major problem that leads to negative functional, psychological, and social consequences. Bimatoprost is an ophthalmic prostamide analog that is approved by the United States Food and Drug Administration for the treatment of eyelash hypotrichosis. Its proposed mechanism is stimulation of the prostaglandin receptor in dermal papilla and melanocyte, thus leading to a prolonged anagen phase and increased melanogenesis. The hair follicle then increases in thickness, length, and darkness. The efficacy of bimatoprost for the treatment of eyebrow hypotrichosis has been supported by well-controlled studies. Bimatoprost, which is noninvasive, effective, and well tolerated, is worth considering as a treatment option for eyebrow hypotrichosis.

Efficacy of topical latanoprost versus minoxidil and betamethasone valerate on the treatment of alopecia areata

BACKGROUND

Alopecia areata (AA) is one of the most common causes of localized hair loss. There is no universally proven therapy that induces and sustains remission of hair growth in AA.

OBJECTIVE

To compare the efficacy and safety of topical latanoprost, minoxidil and betamethasone valerate on hair growth in patients with AA.

PATIENTS AND METHODS

Hundred patients with AA classified into five groups of 20 treated with: Group I, latanoprost 0.1% lotion; Group II, minoxidil 5% lotion; Group III, betamethasone valerate 0.1% solution; Group IV, combination of latanoprost lotion and betamethasone valerate solution and Group V, a vehicle lotion control group.

RESULTS

There was a statistically significant improvement in all therapeutic groups when compared with control group and reduction of severity of alopecia tool score of scalp and beard before and after treatment for all therapeutic groups.

CONCLUSION

Latanoprost, minoxidil and betamethasone valerate are effective and safe in the treatment of patchy AA. The use of latanoprost added to the therapeutic efficacy of topical betamethasone valerate in the treatment of AA and could be an effective adjunctive topical therapy for AA.

Molecular cloning and expression analysis of prostaglandin E receptor 2 gene in cashmere goat (Capra hircus) skin during hair follicle development

As a member of the four subtypes of receptors for prostaglandin E2 (PGE2), prostaglandin E receptor 2 (PTGER2) is in the family of G-protein coupled receptors and has been characterized to be involved in the development and growth of hair follicles. In this study, we cloned and characterized the full-length coding sequence (CDS) of PTGER2 gene from cashmere goat skin. The entire open reading frame (ORF) of PTGER2 gene was 1047 bp and encoded 348 amino acid residues. The deduced protein contained one G-protein coupled receptors family 1 signature, seven transmembrane domains, and other potential sites. Tissue expression analysis showed that PTGER2 gene was expressed strongly in the skin. The general expression tendency of PTGER2 gene at different hair follicle developmental stages in the skin was gradually decreased from anagen to catagen to telogen. After comparing with the expression of BMP4 gene and related reports, we further presume that it seems to have a relationship between the hair follicle cycle and the expression level of PTGER2 gene in cashmere goat skin.

Hair follicular expression and function of group X secreted phospholipase A2 in mouse skin

Although perturbed lipid metabolism can often lead to skin abnormality, the role of phospholipase A(2) (PLA(2)) in skin homeostasis is poorly understood. In the present study we found that group X-secreted PLA(2) (sPLA(2)-X) was expressed in the outermost epithelium of hair follicles in synchrony with the anagen phase of hair cycling. Transgenic mice overexpressing sPLA(2)-X (PLA2G10-Tg) displayed alopecia, which was accompanied by hair follicle distortion with reduced expression of genes related to hair development, during a postnatal hair cycle. Additionally, the epidermis and sebaceous glands of PLA2G10-Tg skin were hyperplasic. Proteolytic activation of sPLA(2)-X in PLA2G10-Tg skin was accompanied by preferential hydrolysis of phosphatidylethanolamine species with polyunsaturated fatty acids as well as elevated production of some if not all eicosanoids. Importantly, the skin of Pla2g10-deficient mice had abnormal hair follicles with noticeable reduction in a subset of hair genes, a hypoplasic outer root sheath, a reduced number of melanin granules, and unexpected up-regulation of prostanoid synthesis. Collectively, our study highlights the spatiotemporal expression of sPLA(2)-X in hair follicles, the presence of skin-specific machinery leading to sPLA(2)-X activation, a functional link of sPLA(2)-X with hair follicle homeostasis, and compartmentalization of the prostanoid pathway in hair follicles and epidermis.

Bimatoprost in the treatment of eyelash hypotrichosis

Eyelashes hypotrichosis is a condition indicated by an inadequate amount of eyelashes. Hypertrichosis of eyelashes, characterized by excessive eyelash growth, is a regular phenomenon associated with ophthalmic prostaglandin and prostamide analogs. Recently, the US Food and Drug Administration approved Latisse((R)) (bimatoprost 0.03% solution), identical to the ophthalmic solution for glaucoma treatment, for increasing eyelash length, thickness and darkness in patients with hypotrichosis of the eyelashes. When prostaglandin and prostamide analogs interact with the prostanoid receptors in the hair follicle, this most likely stimulates the resting follicles (telogen phase) to growing follicles (anagen phase). Prostaglandin and prostamide analogs may also prolong the anagen phase of eyelashes, leading to an increase of eyelash length. Although bimatoprost is effective in promoting increased growth of healthy eyelashes and adnexal hairs, its effectiveness in patients with eyelash alopecia areata is debatable and its protective effect is not yet studied in patients with eyelash loss secondary to radiation or chemotherapy. Bimatoprost is generally safe when applied to the base of the eyelashes at the lid margin with minimum side effects. However, other ocular or systemic side effects associated with ophthalmic prostaglandin and prostamide analogs may occur when instilled on the surface of the eye, and patients must be informed and monitored.

Eyelash growth from application of bimatoprost in gel suspension to the base of the eyelashes

OBJECTIVE

To determine whether bimatoprost (Lumigan, Allergan Inc., Irvine, CA) causes increased lash length when used in gel suspension applied to the base of the eyelashes.

DESIGN

Randomized controlled trial.

PARTICIPANTS

Nineteen subjects were enrolled.

METHODS

Subjects recruited from the Bascom Palmer Eye Institute were screened, and those who met inclusion criteria were enrolled. Each participant received 2 vials of gel suspension, which contained bimatoprost and normal saline, respectively, each mixed 1:1 with Gonak gel (Akorn Inc., Lake Forest, IL) and labeled "right eye" and "left eye" according to randomization. The suspension was applied to the upper eyelid eyelashes every evening on the designated eye for 6 weeks.

MAIN OUTCOME MEASURES

Lash length was measured with a caliper at enrollment, at weekly intervals during the application of the gel, and at 1 and 3 months after discontinuation of its use. Visual acuity, ocular symptoms, intraocular pressure, and photographs were documented at these same intervals.

RESULTS

The mean eyelash growth from baseline in the bimatoprost group was 2.0 mm versus a mean of 1.1 mm in the placebo group, which was a statistically significant difference (P=0.009). The average intraocular pressure decreased equally in both groups (2 mmHg). No change in visual acuity or iris discoloration was noted in any of the subjects.

CONCLUSIONS

Our data showed an increase in eyelash length with the use of bimatoprost in gel suspension, suggesting the product's eyelash-lengthening properties.

Male pattern baldness: current treatments, future prospects

Male pattern baldness affects up to half of the male Caucasian population by middle age, and almost all Caucasian men by old age. Especially in younger men, this heritable form of hair loss can have significant psycho-social consequences. Although approved pharmacological agents exist to manage the condition, none of the currently available options are highly efficacious. New treatments under development, and acceleration in our understanding of the underlying molecular genetic aetiology of this condition provide increased hope for future targeted treatment strategies.

Prostanoid receptors in anagen human hair follicles

Prostanoid pathway in hair follicle gained closer attention since trichogenic side-effects on hair growth has been observed concomitantly with prostaglandin F(2alpha) receptor (FP) agonist treatment of intraocular pressure. We thus investigated prostanoid receptor distribution in anagen hair follicle and different cell types from hair and skin. Using RT-PCR, Western blot and immunohistochemistry (IHC), we found that all receptors were present in hair follicle. This data shed new light on an underestimated complex network involved in hair growth control. Indeed most of these receptors showed a wide spectrum of expression in cultured cells and the whole hair follicle. Using IHC, we observed that expression of prostaglandin E(2) receptors (EP(2), EP(3), EP(4)), prostaglandin D(2) receptor (DP(2)), prostanoid thromboxane A(2) receptor (TP) and to a lesser extent EP(1) involved several hair follicle compartments. On the opposite, Prostaglandin I(2) receptor (IP) and DP(1) were more specifically expressed in hair cuticle layer and outer root sheath (ORS) basal layer, respectively. FP expression was essentially restricted to ORS companion layer and dermal papilla (DP). Although extracting a clear functional significance from this intricate network remains open challenge, FP labelling, i.e. could explain the biological effect of PGF(2alpha) on hair regrowth, by directly modulating DP function.

The expression pattern of prostaglandin E synthase and EP receptor isoforms in normal mouse skin and preinvasive skin neoplasms

Prostaglandin (PG) E(2), the predominant PG in skin, accumulates in experimentally produced mouse skin tumors. PGE(2) induces proliferation of mouse keratinocytes in vitro, epidermal hyperplasia and dysplasia, a promoted epidermis phenotype, and angiogenesis in keratin 5 promoter (K5) cyclooxygenase (COX)-2-transgenic NMRI mouse skin in vivo. PGE(2) is synthesized by COX-catalysed oxygenation of arachidonic acid to PGH(2) and its conversion to PGE(2) by prostaglandin E synthase (PGES) isoforms. PGE(2) signals via PGE(2) receptor isoforms EP1-EP4. Here, we investigated the expression profiles of PGES and EP receptors in wild type NMRI mouse skin constitutively expressing COX-1 when compared with the hyperplastic/dysplastic skin of homozygous K5 COX-2-transgenic mice and papillomas of both genotypes, which, in addition to COX-1, overexpress COX-2. The three PGES are constitutively expressed in normal and transgenic skin independent of the COX expression status. In papillomas, the increased PGE(2) levels correlate with an increased expression of mPGES-1 and cPGES. All four EP receptors were expressed in normal and transgenic skin. Only EP3 was slightly increased in transgenic skin. In papillomas of both genotypes, the expression levels of EP1 and EP4 were low when compared with those in wild type back skin. EP2 was the predominant receptor in papillomas of wild type and transgenic mice. In papillomas of wild type mice EP3 levels were slightly elevated when compared with transgenic tumors. EP1 and EP2 were localized in basal keratinocytes, sebaceous glands and CD31-positive vessels. Thus, normal and preinvasive mouse skin express the complete protein repertoire for PGE(2) biosynthesis and signalling.

Orally administered FPRL1 receptor agonist peptide MMK-1 inhibits etoposide-induced alopecia by a mechanism different from intraperitoneally administered MMK-1

Oral administration for 6 days of 100 mg/kg MMK-1, an agonist peptide selective for the FPRL1 receptor, suppressed alopecia induced by the anticancer drug etoposide in neonatal rats. The anti-alopecia effect of orally administered MMK-1 was not inhibited by pyrilamine or cimetidine, antagonists for histamine H1 and H2 receptors, respectively, which blocked the anti-alopecia effect of intraperitoneally administered MMK-1 at a dose of 10 mg/kg for 4 days. However, the anti-alopecia effect of orally administered MMK-1 was inhibited by indomethacin, an inhibitor of cyclooxygenase (COX), or AH-23848B, an antagonist of the EP4 receptor for prostaglandin (PG) E2, suggesting involvement of PGE2 release and the EP4 receptor in the oral MMK-1 anti-alopecia mechanism. The anti-alopecia effect of orally administered MMK-1 was also blocked by an inhibitor of nuclear factor-kappaB (NF-kappaB), pyrrolidine dithiocarbamate, suggesting that the oral anti-alopecia effect of MMK-1 may be mediated by activation of NF-kappaB. These results suggest that MMK-1 bound to FPRL1 receptor might suppress etoposide-induced apoptosis of hair follicle cells and alopecia by way of PGE2 release and NF-kappaB activation.

Prostaglandin E receptor EP3 deficiency modifies tumor outcome in mouse two-stage skin carcinogenesis

We have recently shown that the prostaglandin E(2) (PGE(2)) receptor EP(3) plays an important role in suppression of colon cancer cell proliferation and that its deficiency enhances late stage colon carcinogenesis. Here we examined the effects of EP(3)-deficiency on two-stage skin carcinogenesis. 7,12-Dimethylbenz[a]anthracene (50 microg/200 microl of acetone) was thus applied to the back skin of female EP(3)-knockout and wild-type mice at 8 weeks of age, followed by treatment with 12-O-tetradecanoylphorbol-13-acetate (5 microg/200 microl of acetone) twice a week for 25 weeks. First tumor appearance was observed in EP(3)-knockout mice at week 10, which was 3 weeks later than in EP(3) wild-type mice, and multiplicity observed at week 11 was significantly lower in the EP(3)-knockout case. However, histological examination showed that the tumor incidence and multiplicity at week 25 were not significantly changed in knockout mice and wild-type mice (incidence, 19/19 versus 23/24; multiplicity, 3.58 +/- 0.51 versus 3.17 +/- 0.63, respectively). Interestingly, there were no squamous cell carcinomas (SCCs) in the EP(3)-knockout mice, while SCCs were observed in 3 out of 24 wild-type mice. Furthermore, benign keratoacanthomas only developed in EP(3)-knockout mice (6/19 versus 0/24, P < 0.01). The results suggest that PGE(2) receptor EP(3) signaling might contribute to development of SCCs in the skin.

Anti-alopecia mechanisms of soymetide-4, an immunostimulating peptide derived from soy beta-conglycinin

Previously, we found that orally administered soymetide-4 (MITL), an immunostimulating peptide derived from soybean beta-conglycinin alpha' subunit, suppressed alopecia induced by the anti-cancer drug etoposide in neonatal rats. Soymetide-4 has weak affinity for N-formyl-methionyl-leucyl-phenylalanine (fMLP) receptor. fMLP showed an anti-alopecia effect after intraperitoneal administration, though it was inactive after oral administration. Anti-alopecia effect of fMLP was blocked by pyrilamine or cimetidine, antagonists for histamine H1 or H2 receptor, respectively. However, the anti-alopecia effect of soymetide-4 was not inhibited by the histamine antagonists but by indomethacin, an inhibitor of cyclooxygenase (COX), or AH-23848B, an antagonist of the EP4 receptor for PGE2. Anti-alopecia effect of soymetide-4 was also blocked by pyrrolidine dithiocarbamate, an inhibitor of nuclear factor-kappaB (NF-kappaB). These results suggest that PGE2, which is produced after activation of COX by soymetide-4, might suppress apoptosis of hair matrix cells and etoposide-induced alopecia by activating NF-kappaB.

Prostanoids in the cutaneous immune response

Prostanoids, consisting of the prostaglandins and the thromboxanes, are the cyclooxygenase metabolites of arachidonic acid. They exert a range of actions mediated by their respective receptors expressed in the target cells. In the skin, it is well known that prostanoids are abundantly produced and that the prostanoid receptors are highly expressed. However, the physiological role of prostanoids in the skin has not been clarified. Recent developments in the molecular biology of the prostanoid receptors have enabled the investigation of the physiological roles of each receptor by disruption of the respective genes in combination with prostanoid receptor selective compounds. Here, we review novel findings relating to the roles of prostanoids in the cutaneous immune responses. These may prove useful in the development of new therapeutic agents that can selectively manipulate the actions mediated by each receptor.

Cyclooxygenases in the skin: pharmacological and toxicological implications

Cyclooxygenase (COX), a prostaglandin-endoperoxide synthase (PTGS), catalyzes the formation of prostaglandins from arachidonic acid. Prostaglandins are lipid signaling mediators that play a central role in a broad range of diverse physiological and pathophysiological processes, including inflammation, reproduction, nocioception, and gastrointestinal protection. Inhibition of cyclooxygenase activity is the mechanism by which nonsteroidal antiinflammatory drugs (NSAIDS) exert their analgesic, antipyretic, antiinflammatory, and antithrombotic effects. COX is currently believed to exist in three isoforms. In this review, we provide a concise state-of-the-art description of the role of COX in pharmacology and toxicology of skin including its involvement in normal physiology, cutaneous inflammation, nociception, wound healing, and tumorigenesis. COX-dependent pathways influence keratinocyte differentiation, hair follicle development, and hair growth. The critical role of COX-2 in pathophysiology of skin is also addressed. COX-2 mediates inflammatory processes in skin, including inflammatory hyperalgesia and nociception, and administration of specific COX-2 inhibitors reduces edema, vascular permeability, and other markers of cutaneous inflammation. A number of studies in animal models and in humans show that COX-2 inhibitors possess cancer chemopreventive properties. Selective COX-2 inhibitors have a more favorable side-effect profile. Topical formulations of COX-2 inhibitors are being developed as a novel pharmacologic approach for the treatment of COX-2 mediated skin diseases.

Expression of Cyclooxygenase Isozymes During Morphogenesis and Cycling of Pelage Hair Follicles in Mouse Skin: Precocious Onset of the First Catagen Phase and Alopecia upon Cyclooxygenase-2 Overexpression

Cyclooxygenase (COX)-1 and -2 catalyze the key reaction in prostaglandin biosynthesis. Whereas COX-1 is found in most tissues, COX-2, with a few exceptions, is not expressed in normal tissues but becomes transiently induced in the course of inflammatory reactions. In many neoplastic epithelia, COX-2 is constitutively overexpressed. Here we show that COX isozymes are spatiotemporally expressed during morphogenesis of dorsal skin epithelium of NMRI mice. COX-1 and COX-2 mRNA and protein were detected in embryonic and postnatal epidermal tissue by RT-PCR, northern blot, and immunoblot analysis indicating that both isoforms may contribute to prostaglandin production. Being barely detectable in interfollicular epidermis and resting hair follicles of adult mice, COX-2 protein appeared in embryonic skin first in epidermal precursor cells and later on in the basal cells and the peridermal layer of the stratified epidermis. In the course of pelage hair follicle morphogenesis, COX-2 remained expressed in the basal interfollicular compartment and, in addition, became apparent in elongated hair germs and hair pegs and later on in the outer root sheath cells of the distal and proximal hair follicles as well as in basal sebaceous gland cells. During the subsequent synchronous phases of hair cycling, COX-2 expression declined in catagen, was barely detectable in telogen, and was reinduced in the basal outer root sheath and basal sebaceous gland cells of anagen hair follicles. COX-1 immunosignals were detected predominantly in the interfollicular spinous and granular layers of the developing, neonatal, and adult epidermis but not in follicular epithelial cells of developing or cycling hair follicles. Dendritic cells in the interfollicular epidermis and distal hair follicles were also COX-1-positive. Transgenic overexpression of COX-2 under the control of a keratin 5 promoter in basal cells of the interfollicular and follicular epidermis induced a precocious entry into the first catagen stage of postnatal hair follicle cycling and a subsequent disturbance of hair follicle phasing. Furthermore, transgenic mice developed an alopecia. Inhibition of transgenic COX-2 activity by feeding the specific COX-2 inhibitor valdecoxib suppressed the development of alopecia, indicating that COX-2-mediated prostaglandin synthesis is involved in hair follicle biology.