Inhibition of collagen degradative enzymes by retinoic acid in vitro

A prospective, randomized, split-face study of concomitant administration of low-dose oral isotretinoin with 30% salicylic acid chemical peeling for the treatment of acne vulgaris in Asian population

BACKGROUND

Acne vulgaris (AV) is a common dermatosis. For moderate to severe AV, isotretinoin is the first-line treatment. Chemical peeling with supramolecular salicylic acid (SSA) was developed with water solubility and advanced skin penetration properties. In the present study, we investigated the efficacy and safety of oral low-dose isotretinoin combined with 30% SSA chemical peeling.

METHODS

Thirty-three moderate-to-severe acne patients were enrolled and received oral low-dose (0.2-0.4 mg/kg/d) isotretinoin and were then randomly assigned to receive 30% SSA or not on each side of the face with 2-week intervals for four sessions. Photos, the number of lesions, GAGS score, skin indices (melanin, erythema, pore, and texture), hydration, and transepidermal water loss (TEWL) were assessed at 0, 2, 4, 6, and 10 weeks. Side effects, efficacy, and satisfactory rates were recorded.

RESULTS

A total of 29 patients completed the study. Oral isotretinoin combined with SSA decreased response time compared to isotretinoin monotherapy, with significantly improved GAGS score, count of lesions, and efficacy (%) at 4-6 weeks. Skin indices of melanin, erythema, pore, and texture evaluated at week 10 were improved as well. Oral isotretinoin with or without SSA was effective by the lesion clearance; only SSA significantly improved the TEWL. All the side effects were temporary and tolerable, and no adverse effects were observed.

CONCLUSION

Oral low-dose isotretinoin combined with 30% SSA is safe and effective, which advanced the onset of action and improves lesion clearance.

Collagenase inhibition by water-pepper (Polygonum hydropiper L.) sprout extract

Introduction: Collagenase plays an important role in the degradation of dermal matrix proteins leading to wrinkle formation. The objectives of this study were to evaluate the inhibitory effect of water-pepper (Polygonum hydropiper L.) sprout extract on the activity of collagenase and to identify the inhibitory compounds.Methods: Collagenase inhibitory activity was measured by spectrophotometric assay. Activity-guided fractionation was performed using liquid-liquid extraction of water and n-butanol and Diaion HP-20 column chromatography, followed by high-performance liquid chromatography (HPLC) fraction collection.Results: A methanolic extract of water-pepper sprout inhibited collagenase activity in a concentration-dependent manner with an IC50 value of 156.7 μg/mL. Collagenase inhibitory activity (IC50 = 23.5 μg/mL) was found in 50% methanol eluate from the HP-20 column chromatography of the n-butanol soluble fraction. The active compound (IC50 = 1.9 μg/mL) in the eluate was isolated by HPLC and identified as quercetin-3-O-galactoside (hyperoside) from comparing retention time, UV-Vis absorption, and mass spectra with those of the standard. Lineweaver-Burk plots revealed that hyperoside was an uncompetitive inhibitor against collagenase. Hyperoside was also the most abundant flavonoid present in the methanolic extract.Conclusion: These results suggest that water-pepper sprouts could be beneficial as a natural source of collagenase inhibitor which might be used for the treatment of skin aging.

Effects of oral ısotretinoin on normal and wounded nasal mucosa: an experimental study

BACKGROUND

We aimed to investigate the effect of systemic isotretinoin therapy on normal and wounded nasal septal mucosa histopathologically in an experimental rabbit model.

METHODS

Circular mucosal defect with a 7 mm diameter was made in the left septum of 12 New Zealand white rabbits. The rabbits were divided into two groups (six rabbits in each group) oral isotretinoin was given with olive oil at the operation day to the first group. The control group was only oil given group. The harvested septum mucosas were divided into four groups (1-wounded-drug given side, 2-unwounded and drug-given side, 3-wounded-control and 4-unwounded-control side). The diameter of the defect, mucosal thickness, epithelial thickness, ciliated cell level, goblet cell level and inflammation were evaluated every week for 4 weeks.

RESULTS

At both wounded and normal side, thinning of normal respiratory ciliated epithelium was observed in the postoperative period. In study group at the wounded side; mean mucosal thickness was measured 139.66 µ (± 26.24), and in the control group, mean mucosal thickness was 238.33 µ (± 39.7) at the wounded side. (p < 0.001). The difference between the groups in thickness of normal septal mucosa was also statistically significant (p = 0.016) [190 µ (± 14.6) and 256.66 µ (± 44.66)]. The average cilia level was observed 1.16 in the wounded study group, while the average level was 2.33 in the wounded control group (p = 0.012). Average score measurements of the regenerated mucosa suggested that isotretinoin-given wounded animals have reduced goblet cell recovery, compared to the control both on the regenerated and unwounded mucosas (p = 0.007, p = 0.002, respectively). Inflammation was significantly higher in the wounded isotretinoin group (p = 0.018).

CONCLUSION

Oral isotretinoin has negative effects on epithelial and ciliary regeneration, significantly reduces mucosal thickness and goblet cell counts of the normal and regenerated mucosa, causes severe inflammation and significant reactive changes.

Retinoic acid for treatment of systemic sclerosis and morphea: A literature review

Systemic sclerosis and morphea are connective tissue diseases characterized by tightening, thickening, and hardening of the skin, leading to significant morbidity. Unfortunately, current treatment options have limited efficacy for many patients. Cutaneous manifestations of these diseases arise from excess collagen deposition and fibrosis in the skin, through pathogenic mechanisms which have yet to be extensively detailed at the causal immune and cellular levels. Research elucidating the mechanism of action of retinoic acid on collagen production in the skin and case series highlighting the success of retinoic acid on the skin manifestations of systemic sclerosis and on morphea demonstrate its promise as a treatment. Herein they will briefly review the treatment options for both systemic sclerosis and morphea, and will discuss the potential of retinoic acid as a therapy and the supporting evidence from the literature, highlighting the previously published basic science and clinical studies investigating the role of retinoic acid in the treatment of sclerotic skin diseases.

Inhibition of matrix metalloproteinases expression in human dental pulp cells by all-trans retinoic acid

All-trans retinoic acid (ATRA) inhibits matrix metalloproteinase (MMP)-2 and MMP-9 in synovial fibroblasts, skin fibroblasts, bronchoalveolar lavage cells and cancer cells, but activates MMP-9 in neuroblast and leukemia cells. Very little is known regarding whether ATRA can activate or inhibit MMPs in human dental pulp cells (HDPCs). The purpose of this study was to determine the effects of ATRA on the production and secretion of MMP-2 and -9 in HDPCs. The productions and messenger RNA (mRNA) expressions of MMP-2 and -9 were accessed by gelatin zymography and real-time polymerase chain reaction (PCR), respectively. ATRA was found to decrease MMP-2 level in a dose-dependent manner. Significant reduction in MMP-2 mRNA expression was also observed in HDPCs treated with 25 µmol⋅L(-1) ATRA. However, HDPCs treated with ATRA had no effect on the pattern of MMP-9 produced or secreted in either cell extracts or conditioned medium fractions. Taken together, ATRA had an inhibitory effect on MMP-2 expression in HDPCs, which suggests that ATRA could be a candidate as a medicament which could control the inflammation of pulp tissue in vital pulp therapy and regenerative endodontics.

Possible isotretinoin-induced keloids in a patient with Behcet's disease

Isotretinoin-induced keloid formation has occasionally been reported in patients who have undergone dermabrasion or laser treatment. This report describes a man with Behçet's disease (BD) who was prescribed isotretinoin for nodulocystic acne. After approximately 8 weeks of this treatment, the patient developed extensive keloids. There are no previous reports of possible isotretinoin-induced keloid formation in the setting of BD. This article discusses possible connections between BD, keloid formation and isotretinoin, which may be manifested in this case.

Complications associated with isotretinoin use after rhinoplasty

BACKGROUND

This study aimed to evaluate the association between the postoperative use of isotretinoin and the formation of nasal tip deformities after rhinoplasty.

METHODS

A retrospective study investigated a case series of patients who presented with nasal tip deformities subsequent to the use of isotretinoin after rhinoplasty. Patients who had taken isotretinoin after rhinoplasty were identified from a single surgeon's case log. Clinic charts and operative reports were reviewed. Predisposing factors and time intervals to complications were identified.

RESULTS

Three patients were found to have undergone isotretinoin therapy after rhinoplasty. Nasal tip deformities included bossa formation, asymmetry, and prominence of a composite graft. All three patients required subsequent procedures to repair soft tissue nasal tip deformities. In all three cases, isotretinoin was started within 2 years of the primary rhinoplasty. The nasal tip deformities were first observed within 6 months after isotretinoin was started.

CONCLUSIONS

Three cases are described in which postoperative use of isotretinoin was associated with nasal tip deformities after rhinoplasty. Further studies are needed to investigate this possible causative relationship and to describe the risks involved.

Chemoprevention of squamous cell carcinoma in recessive dystrophic epidermolysis bullosa: results of a phase 1 trial of systemic isotretinoin

BACKGROUND

Patients with recessive dystrophic epidermolysis bullosa (RDEB) are at high risk of developing squamous cell carcinoma on or after midadolescence, and most patients die of metastatic squamous cell carcinoma within 5 years of diagnosis of their first squamous cell carcinoma.

OBJECTIVE

We sought to determine whether isotretinoin can be safely administered to patients with RDEB as a possible chemopreventive agent.

METHODS

A total of 20 patients with RDEB aged 15 years or older were treated daily for 8 months with isotretinoin (with a targeted dosage of 0.5 mg/kg/d).

RESULTS

No unusual adverse reactions were noted in this patient population. Several patients experienced reduced blistering at lower doses and increased mechanical fragility at maintenance dosage.

CONCLUSIONS

Isotretinoin, at least up to a dosage of 0.5 mg/kg/d, may be safely used in patients with RDEB. Although increased fragility may occur, patients tolerated this drug well and were receptive to its long-term use for possible chemoprevention of cancer. Whether such an effect will occur is yet to be proven.

Modulation of type VII collagen (anchoring fibril) expression by retinoids in human skin cells

We examined the effects of retinoids on the expression of type VII collagen, a major component of anchoring fibrils, in human keratinocytes and amnion cells (WISH). All-trans retinoic acid (RA) (5 X l0(-6) M) decreased the steady-state levels of type VII collagen mRNA by at least 80% after 18 h. The inhibition was evident within 6 h after the addition of RA, maximal at 18 h, and was dose-dependent. Reduction of type VII mRNA expression also occurred when cell cultures were incubated with retinol, retinal, and 13-cis RA. Retinoid-mediated inhibition of type VII collagen mRNA expression was observed in keratinocytes growing in either serum-free keratinocyte growth medium (KGM) or KGM supplemented with 1.4 mM Ca2+. Cycloheximide blocked RA-mediated inhibition of type VII collagen mRNA, demonstrating the need for de novo protein synthesis. The mRNA levels for fibronectin and glyceraldehyde phosphate dehydrogenase were not affected by the retinoids, suggesting selective inhibition on type VII collagen expression. In addition, the decrease in type VII collagen mRNA was accompanied by a parallel decrease in secretion of the 290 kDa, type VII collagen alpha chains.

Radiation therapy for squamous cell carcinoma in dystrophic epidermolysis bullosa: case reports and literature review

Dystrophic epidermolysis bullosa (DEB) is a debilitating systemic disease frequently associated with biologically aggressive secondary squamous cell carcinomas arising from affected skin or mucosal surfaces. Treatment of these carcinomas with surgery, chemotherapy, or radiation is complicated by inherently poor wound healing. We report on two DEB patients treated with radiation therapy for locally advanced squamous cell carcinoma, and retrospectively analyze 10 DEB patients treated with radiation, reported in the literature. Of the 11 fully available and described case results from radiation therapy, six (54%) patients demonstrated a partial tumor response. All patients receiving > 4,500 cGy developed moist skin desquamation and delayed skin healing. Radiation therapy may be of benefit in palliating DEB patients who have locally advanced carcinoma, but has been associated with enhanced normal tissue toxicity, suggesting a narrow or absent therapeutic index between irradiated carcinoma and skin.

Systemic oral isotretinoin therapy and flow rate, pH, and matrix metalloproteinase-9 activity of stimulated saliva

Systemic retinoids are known to cause dryness of the mouth and changes in oral and lip mucosa. The purpose of this study was to evaluate changes in salivary variables during treatment with oral isotretinoin in patients receiving the drug for 3 months for cutaneous acne. Patients were examined 1 month after initiation of medication and approximately 3.7 months after its discontinuation. Salivary flow and pH could be measured in 8 and the relative amount of matrix metalloproteinase-9 (MMP-9) of stimulated saliva in 17 patients. The mean flow rate of stimulated saliva was lower during medication than at control examination (P = 0.0277), but no change in the mean pH value was observed during medication. The mean activity of MMP-9 during medication was higher than at control examination (P = 0.0442). The enzyme activity increased in 13 of 17 and decreased in 4 of 17 cases.

Treatment of vulvar lichen sclerosus in the elderly: an update

Lichen sclerosus et atrophicus is a disorder of the skin that can occur anywhere on the body and in all age groups but mainly affects middle-aged and elderly women in the vulvoperineal area. It consists of ivory or pink papules or macules that eventually coalesce into thin, gray, parchment-like areas. Clinically, the main symptoms are severe and intractable itching and vaginal soreness with dyspareunia. Although it has been described to be associated with an increased risk for epithelial malignancy this, in fact, very rarely occurs. The exact nature of LSA is still unknown. The accumulation of evidence does little to clarify its pathogenesis and etiology. The different reports indicate at least three general possibilities; autoimmune, metabolic, and more recently infectious etiology. The coexistence of such diverse findings in one disease entity may indicate one of the two; either we are facing a group of very similar conditions, which will be separated in the future into several closely related clinical entities, each with its own etiology, or that all findings represent a complex multi-step single pathogenetic mechanism. The latter possibility seems more probable because it has previously been suggested that B. burgdorferi, a recent prime suspect in the pathogenesis of LSA, may induce both metabolic and autoimmune abnormalities in the course of infection. New therapeutic options and attitudes emerge that dramatically improved the conservative treatment of this disease (Table 5).(ABSTRACT TRUNCATED AT 250 WORDS)

All-trans retinoic acid (RA) stimulates events in organ-cultured human skin that underlie repair. Adult skin from sun-protected and sun-exposed sites responds in an identical manner to RA while neonatal foreskin responds differently

Adult human skin from a sun-protected site (hip) and from a sun-exposed site (forearm) was maintained in organ culture for 12 d in the presence of a serum-free, growth factor-free basal medium. Cultures were incubated under conditions optimized for keratinocyte growth (i.e., in 0.15 mM extracellular Ca2+) or for fibroblast growth (i.e., in 1.4 mM extracellular Ca2+). Treatment with all-trans retinoic acid (RA) induced histological changes in the organ-cultured skin under both conditions which were similar to the changes seen in intact skin after topical application. These included expansion of the viable portion of the epidermis and activation of cells in the dermis. In sun-damaged skin samples, which were characterized by destruction of normal connective tissue elements and presence of thick, dark-staining elastotic fibers, a zone of healthy connective tissue could be seen immediately below the dermo-epidermal junction. This zone was more prominent in RA-treated organ cultures than in matched controls. Associated with these histological changes was an increase in overall protein and extracellular matrix synthesis. In concomitant studies, it was found that RA treatment enhanced survival and proliferation of adult keratinocytes and adult dermal fibroblasts under both low- and high-Ca2+ conditions. In all of these assays, responses of sun-protected and sun-exposed skin were identical. In contrast, responses of neonatal foreskin to RA were similar to those of adult skin in the presence of low-Ca2+ culture medium, but under conditions of high extracellular Ca2+ RA provided little or no additional stimulus. Together these studies suggest that the ability of RA to enhance repair of sun-damaged skin (documented in previous studies) may reflect its ability to influence the behavior of skin in a manner that is age dependent but independent of sun-exposure status.

all-trans-retinoic acid preserves viability of fibroblasts and keratinocytes in full-thickness human skin and fibroblasts in isolated dermis in organ culture

Human dermal fibroblast and human epidermal keratinocyte survival was examined under various conditions in organ culture. Using cell recovery from organ-cultured tissue as the criterion, it was observed that no keratinocytes and few fibroblasts survived incubation for 10-12 days in serum-free basal medium containing a low level (0.15 mM) of extracellular Ca2+. Increasing the extracellular Ca2+ concentration to 1.4 mM or treating the tissue with 3 microM retinoic acid (RA) under low Ca2+ conditions resulted in increased keratinocyte and fibroblast survival; the two treatments together were more effective than either treatment alone. The same treatments preserved fibroblast survival when pieces of isolated dermal tissue were incubated in organ culture and also supported fibroblast survival in monolayer culture. These findings indicate that recovery of keratinocytes and fibroblasts from skin after maintenance in organ culture provides a simple but definitive measure of the viability of the major cellular elements present in the tissue. These findings suggest that RA treatment enhances survival of both fibroblasts and keratinocytes and that these effects of RA can be seen at physiological Ca2+ concentrations as well as at suboptimal levels of extracellular Ca2+. Finally, these results indicate that the dermis is a direct target of RA.

Atypical facial scarring after isotretinoin therapy in a patient with previous dermabrasion

The increased use of isotretinoin therapy for severe cystic acne has posed new problems for dermatologic surgeons. There have been recent reports in the literature of unexpected "atypical" scarring after dermabrasion in patients who have previously taken isotretinoin. This scarring was considered atypical because it occurred outside the typical "danger zones" (e.g., mandible and malar eminences) where scarring most often occurs after dermabrasion. This is the first reported case of atypical scarring in a patient who began isotretinoin therapy 2 months after dermabrasion.

Restoration of collagen formation in photodamaged human skin by tretinoin (retinoic acid)

BACKGROUND

Topical tretinoin (retinoic acid) modifies fine wrinkles and certain other features of human skin damaged by exposure to the sun (photodamage), but histologic changes do not account for this improvement. In mice with photodamage induced by ultraviolet light, effacement of fine wrinkles by tretinoin is correlated with dermal collagen synthesis but not with histologic changes. We investigated whether collagen synthesis was reduced in photodamaged human skin and, if so, whether it could be restored by treatment with topical tretinoin.

METHODS

Biopsies of photodamaged skin from the extensor aspect of the forearm and skin from the buttocks, which had been protected from the sun, were performed on 26 healthy subjects. In addition, 29 patients with photodamaged skin were treated for 10 to 12 months with a daily application of 0.1 percent tretinoin cream (15 patients) or vehicle cream (14 patients). Skin-biopsy specimens obtained at base line and after treatment were assessed immunohistologically for evidence of dermal collagen I formation (collagen synthesis).

RESULTS

Collagen I formation was 56 percent less in the papillary dermis of photodamaged skin than in skin protected from the sun (P < 0.001) and was correlated with the clinical severity of photodamage (r = -0.58, P = 0.002). Treatment of photodamaged skin with tretinoin produced an 80 percent increase in collagen I formation, as compared with a 14 percent decrease in collagen formation with the use of vehicle alone (P = 0.006).

CONCLUSIONS

The formation of collagen I is significantly decreased in photodamaged human skin, and this process is partly restored by treatment with tretinoin.

The secretion of the tissue inhibitor of metalloproteinases (TIMP) by human synovial fibroblasts is modulated by all-trans-retinoic acid

The matrix metalloproteinases are a family of enzymes involved in the turnover of the connective tissues. The regulation of these enzymes is complex, involving the control of synthesis, the activation of proenzyme forms and the presence of specific inhibitors. Retinoids have been reported to inhibit the production of metalloproteinases by human and rabbit synovial fibroblasts and by human skin fibroblasts. The production of the highly specific tissue inhibitor of metalloproteinases (TIMP) by connective tissue cells may be crucial in the regulation of connective tissue breakdown and this present study was undertaken to determine if retinoic acid (RA) could modulate TIMP and collagenase production by synovial fibroblasts. The results show that RA at concentrations from 10(-7) to 10(-5) M significantly stimulated the secretion of TIMP by two of three human synovial cell lines. The effect of mononuclear cell factor (MCF) on TIMP and collagenase levels was also investigated. The apparent reduction of collagenase levels in the presence of RA, could result from a failure to accurately measure this enzyme in the presence of increased levels of TIMP.

Ultraviolet radiation in skin ageing and carcinogenesis: the role of retinoids for treatment and prevention

The mechanisms of UV-induced ageing and carcinogenesis of the skin have been elucidated in animals and humans, and both UVB and UVA radiation have been shown to have deleterious effects on the skin. Thus the use of solaria which deliver mostly UVA radiation is not safe. There is also an increased risk of ageing when using therapeutic UV sources. UV radiation is beneficial in many cases of skin disorders such as psoriasis, atopic eczema, acne and pruritus. Nevertheless by careful patient selection and follow-up the risks of UV can be minimised when treating patients with artificial UV radiation. During recent years there has been intensive research into the development of agents which prevent harmful effects of radiation. The retinoids are particularly interesting as they enhance skin repair after UV damage, have an anticarcinogenic effect and are effective for treating precancerous lesions such as solar keratosis and as adjuvant therapy for skin cancers. Topical retinoids are already used for the treatment of actinic skin damage, and systemic retinoids are also used in certain groups of patients who have an increased risk of contracting skin cancers such as xeroderma pigmentosum.

Systemic isotretinoin: effects on dermal wound healing in a rabbit ear model in vivo

Clinical observations have suggested that wound healing may be altered in patients treated with systemic isotretinoin. In this study, we examined the effects of systemic isotretinoin on dermal wound healing and connective tissue metabolism in a rabbit ear model. Forty 6-mm punch-biopsy wounds were created in the ears of two control rabbits as well as two experimental animals fed isotretinoin, 4 mg/kg per day. Clinical inspection and histologic examination revealed no difference between the control and isotretinoin-treated rabbits in terms of the time required for complete wound healing or the appearance of the final scar. The tissue removed from the wound site at days 0, 7, 14, and 21 after wounding was subjected to analysis of a collagen production and collagen gene expression. Collagen production, determined by the synthesis of [3H]hydroxyproline after incubation of tissue slices with [3H]proline in vitro or by the measurement of the steady-state levels of types I and III procollagen mRNAs, was not significantly different between the two groups. The results indicate that systemic administration of isotretinoin does not affect collagen synthesis in the rabbit ear model of wound healing.

Risk: benefit ratio in the treatment of psoriasis with systemic retinoids

This is a review of the efficacy of etretinate/acitretin in the treatment of psoriasis and of the currently reported side-effects. The data indicate that retinoids bring significant improvement (if not total clearing) with frequent low-morbidity but rarely serious side-effects. The most serious side-effect of etretinate/acitretin is teratogenicity.

Granulation tissue that developed after a minor trauma in a psoriatic patient on long-term etretinate therapy

Synthetic analogues of retinoic acid, isotretinoin in particular, are known to cause granulation tissue in the nail sulcus and healing cystic acne. We observed granulation tissue that developed in a psoriatic patient on long-term oral etretinate therapy (30 mg/day for 3 years), another synthetic analogue of retinoic acid. In August of 1988, the patient, a 44-year-old male, hit his lower leg against a wooden stick, resulting in a laceration. At that time he had relatively limited patches of psoriasis, but his skin was generally thin with telangiectasia, even in areas without psoriasis, probably due to the long-term use of oral etretinate and topical steroid. In spite of treatment with topical disinfectants and oral antibiotics, the wound progressed into granulation tissue surrounded by erythema and multiple punctate erosions with marked secretion of a clear exudate. The histological findings of the granulation tissue included the presence of proliferating microvessels and a relatively dense cell infiltration with a predominance of plasma cells on the sparse edematous connective tissue. Based on these findings, the rash was considered to be retinoid-induced granulation tissue. As compared with previous reports, our case had the following characteristics: development of rash after minor trauma, rash on the lower leg, eosinophil infiltration into the rash. We believe that long-term users of oral etretinate should be cautioned about the potential for delayed wound healing and the formation of granulation tissue.

Retinoic acid inhibits the production of collagenase by human epidermal keratinocytes

Lattices made of collagen and fibroblasts can be used as dermal equivalents to grow human keratinocytes in vitro. When these cultures are performed in a medium containing delipidized serum, the lattice is eventually degraded by the growing epithelium. The digestion of the dermal equivalent is due to the secretion of a collagenase by the keratinocytes. This degradation does not occur in cultures containing total serum or supplemented with retinoic acid. We show in this paper that retinoic acid inhibits the secretion of this keratinocyte collagenase in a dose-dependent manner. In the light of this result, the possible involvement of collagenase inhibition in the therapeutic effect of retinoic acid in skin disorders and skin aging must be considered.

Retinoid binding proteins and human skin

New techniques for the analysis of proteins with specific binding for natural retinoids in human plasma and skin extracts have been developed. Polyacrylamide gel electrophoresis (PAGE), followed by protein blotting with an antiserum specific to retinol-binding protein (RBP), the plasma carrier of retinol, showed that: (1) retinoic acid induced striking conformational changes when bound to RBP, and (2) none of the several synthetic retinoids used in human therapy were found to bind to RBP. This directly confirms and extends previous indirect observations that synthetic retinoids are not delivered to the target organs through RBP. Human skin extracts incubated with either [3H]retinol or [3H]retinoic acid and analyzed by PAGE is a novel technique for the study of cellular retinol-(CRBP) and retinoic acid-(CRABP) binding proteins; it allows one to more specifically analyse these binding proteins and differentiate them from RBP. This technique confirmed and extended our previous observations: (1) CRABP is present in much higher amounts in the epidermis than in the dermis, whereas CRBP is detectable in very low amounts in both tissues, (2) a dramatic increase of CRABP is found in psoriatic plaques and (3) there is an up-modulation of epidermal CRABP during systemic or topical synthetic retinoid therapy. When the ability of some synthetic analogs of retinoic acid to compete with [3H]retinoic acid binding on human skin CRABP was studied, two important observations were made: (1) the analogs that, when given to human subjects were pharmacologically active, were found to be good competitors and vice-versa, (2) no strict correlation was found between the IC50 and the pharmacological potency of the retinoid.

Regulation of the expression of tissue inhibitor of metalloproteinases and collagenase by retinoids and glucocorticoids in human fibroblasts

The regulation of the expression of interstitial collagenase and tissue inhibitor of metalloproteinases (TIMP) was examined in response to both retinoid compounds and glucocorticoids. Effective retinoids induced a dose-dependent, specific increase in the production of TIMP of approximately two- to threefold by monolayer cultures of human fibroblasts derived from various tissues, while simultaneously causing a decrease in collagenase secretion of similar magnitude. These effects were apparent by 8-12 h in culture and disappeared within 24 h after the withdrawal of retinoid compounds. The retinoid effect on TIMP production was mediated via an increased biosynthesis of new inhibitor protein. Similarly, increased steady state levels of TIMP messenger RNA (mRNA) accompanied by decreased quantities of collagenase mRNA were demonstrated, suggesting transcriptional control of the retinoid action. The data suggest that retinoids co-regulate the expression of collagenase and TIMP, and do so in an inverse manner. Dexamethasone caused a dose-dependent, specific decrease in collagenase production without altering the biosynthesis of TIMP. These findings were paralleled by a marked reduction in collagenase mRNA, without any accompanying change in TIMP mRNA. Therefore, TIMP and collagenase expression appear to be independently modulated by glucocorticoids.

Molecular cloning of human synovial cell collagenase and selection of a single gene from genomic DNA

We used a subclone of a rabbit genomic clone for collagenase that cross-hybridizes with human synovial cell messenger RNA (mRNA) to identify a human collagenase complementary DNA (cDNA) clone. The human cDNA clone is 2.1 kilobases (kb) and selects a mRNA transcript of approximately the same size from primary cultures of rheumatoid synovial cells that produce collagenase, but no mRNA is selected from control (nonproducing) synovial fibroblasts. Restriction enzyme analysis and DNA sequence data indicate that our cDNA clone is full length and that it is identical to that recently described for human skin fibroblast collagenase. The cDNA clone identified a single collagenase gene of approximately 17 kb from blots of human genomic DNA. The identity of human skin and synovial cell collagenase and the ubiquity of this enzyme and of its substrates, the interstitial collagens types I, II, and III, imply that common mechanisms controlling collagenolysis throughout the human body may be operative in both normal and disease states.

Vitamin A and wound healing

Retinoids have long been associated with wound healing, but objective data, until recently, have been scarce. Vitamin A deficiency retards repair. Secondly, retinoids restore steroid-retarded repair toward normal. Because vitamin A tends to suppress fibroblasts in cell culture and stimulate steroid-treated macrophages to initiate reparative behavior in tissue, we favor the hypothesis that retinoids are particularly important in macrophagic inflammation, which plays a central role in the control of wound healing. Probably all patients who take anti-inflammatory steroids should control their retinoid intake, but how they should control it is as yet unknown.

Basal cell carcinoma and collagenase

The interaction of connective tissue stroma and epithelial cutaneous cancer is an active area of investigation in dermatology. Studies summarized here explore the role of collagenase in basal cell carcinoma (BCC) invasiveness. Evidence is presented to support the role of a cytokine or cytokines secreted by BCCs that stimulate collagenase production by surrounding stromal fibroblasts. Prospects for further research in this area are proposed.

Atypical keloids after dermabrasion of patients taking isotretinoin

Six patients underwent dermabrasion while on or having recently completed isotretinoin (Accutane) therapy. All patients developed keloids in atypical locations; the keloids eventually responded to topical or intralesional steroid therapy. Retinoids have a modulatory effect on connective tissue metabolism, including suppression of collagenase, which may enhance keloid formation. Dermabrasion should be delayed in those patients taking or recently on isotretinoin therapy.

Granulation tissue proliferation during isotretinoin treatment

Excessive, pseudotumoral granulation tissue proliferations appeared in three patients receiving isotretinoin for nodulocystic acne. A review of the literature disclosed few reports of this unusual adverse reaction. Two clinical patterns have been reported; one in a periungual location and the other occurring in the sites of acne lesions during isotretinoin therapy. Loose edematous connective tissue with small vessels and chronic inflammatory infiltrate were the histologic findings in all three cases.

Elastase and neutral cathepsin production by human fibroblasts: effect of culture conditions on synthesis and secretion

Fibroblasts from normal adult forearm skin and neonatal foreskin were cultured and examined for their ability to synthesize and secrete elastase and neutral cathepsin. All of the cultures examined produced detectable amounts of elastase using insoluble elastin as substrate. An enzyme was also found that hydrolyzed the synthetic elastin substrate, N-succinyl-(Ala)3-p-nitroanilide, but did not degrade insoluble elastin. In addition, activity against the synthetic cathepsin substrate N-benzoyl-DL-phenylalanine-naphthyl ester was found. Inhibitor profiles indicate that the elastin and N-succinyl-(Ala)3-p-nitroanilide degrading activities are due to metalloproteinases. Degradation of N-benzoyl-DL-phenylalanine-naphthyl ester can be inhibited by phenylmethylsulfonyl fluoride. These proteinases were usually found associated with the cell layer. Although activities of the measured proteinases were detected in all cultures, increased or decreased enzyme activities were not predictably related to passage number or length of serum starvation. Degree of confluence also affected proteinase activities. Separation of the dermal-epidermal junction can be produced by the injection of these proteinases into intact mouse skin.

Demonstration of cellular retinoic acid binding protein in cultured human skin fibroblasts

Previous studies have indicated that retinoids, such as all-trans-retinoic acid and 13-cis-retinoic acid, can modulate connective tissue metabolism in human skin fibroblast cultures. Such effects could be mediated through binding of these retinoids to specific cellular binding proteins. In the present study we have demonstrated cellular retinoic acid binding protein using both whole cell and cytosol binding assays with [3H]all-trans-retinoic acid or [3H]13-cis-retinoic acid as the ligand. Specific binding of [3H]all-trans-retinoic acid could be demonstrated by both techniques and the binding could be displaced by unlabelled all-trans-retinoic acid and 13-cis-retinoic acid, but not by retinol or RO-10-9359 (etretinate) in a 100-fold excess. Gel filtration chromatography of the cytosol proteins after incubation with [3H]all-trans-retinoic acid demonstrated that the specific binding protein had an apparent molecular weight of approximately 15 000 daltons. Thus, the cellular retinoic acid binding protein demonstrated in human skin fibroblasts may mediate the effects of the retinoids on connective tissue metabolism in these cells.

Coregulation of collagenase and collagenase inhibitor production by phorbol myristate acetate in human skin fibroblasts

Phorbol myristate acetate (PMA), a tumor promotor known to stimulate collagenase production in fibroblasts and endothelial cells, was examined with regard to its ability to regulate the expression of the collagenase inhibitor secreted by human skin fibroblasts. Confluent human skin fibroblasts were incubated with concentrations of PMA ranging from 10(-11) to 10(-7) M, and the conditioned medium was analyzed by enzyme-linked immunosorbent assay for both immunoreactive collagenase and collagenase inhibitor. PMA stimulated the production of both collagenase and collagenase inhibitor in several cell lines to maximal rates that were very similar, 300 to 350 vs 230 to 330 pmol 10 micrograms DNA-1 48 h-1, respectively. Due to differences in the basal levels of expression of these proteins, such rates reflected a two- to sevenfold stimulation in collagenase production, in comparison to a more uniform two- to threefold enhancement in inhibitor synthesis. Production of inhibitor was 50% of maximal at 7 X 10(-9) M and maximal at 10(-7) M phorbol. This concentration-dependent effect was very similar to that observed for collagenase expression. Total protein synthesis by the phorbol-conditioned cells, as studied by incorporation of [3H]leucine into newly synthesized protein, was not significantly increased, nor was cellular DNA content. The onset of the effect of PMA on inhibitor production occurred between 4 and 8 h, was maximal by 8 h, and continued undiminished for at least another 64 h. After the first 8 h, inhibitor production continued at a roughly constant rate of approximately 10 pmol 10 micrograms DNA-1 h-1. Interestingly, following the removal of phorbol from culture medium, such fibroblasts continued to produce increased quantities of inhibitor protein for at least 72 h. Metabolic labeling studies in which fibroblasts were exposed to [3H]leucine followed by immunoprecipitation using inhibitor-specific antibody suggested that stimulation of inhibitor production by PMA was mediated via an increased synthesis of new inhibitor protein. Therefore, in response to the tumor promoter, PMA collagenase and collagenase inhibitor expression by human skin fibroblasts appear to be coregulated.

Purification of gelatin-specific neutral protease from human skin by conventional and high-performance liquid chromatography

Human skin, maintained in serum-free organ culture, secretes a neutral metalloendopeptidase which is remarkably specific for gelatin. Because the product peptides from the action of collagenase on collagen become denatured into random coil polypeptides of 25000 and 75000 daltons at physiological temperature, it is thought that this "gelatinase" is the second, and possibly the only other enzyme in the pathway of extracellular collagen degradation. New types of high-performance liquid chromatography (HPLC) columns have enabled us to improve the yields of active gelatinase from skin culture medium. Raw medium, which has been dialyzed and lyophilized, is fractionated with ammonium sulfate, and applied to Pharmacia Blue Sepharose in a batch step. The 0.4 M sodium chloride eluate is then subjected to gel filtration on Sephacryl S-200, followed by gradient elution from Amicon Green Sepharose. The fractions with gelatinolytic activity are applied to a Bio-Rad TSK-Phenyl-5PW HPLC column for mild hydrophobic chromatography with a gradient of decreasing ammonium sulfate concentration. In the final step, the enzyme is applied to a Pharmacia Mono-Q FPLC column and eluted with a gradient of sodium chloride. At this point, the enzyme appears as two bands, corresponding to enzymatic activity zymograms on sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Modulation of procollagen gene expression by retinoids. Inhibition of collagen production by retinoic acid accompanied by reduced type I procollagen messenger ribonucleic acid levels in human skin fibroblast cultures

Recent clinical observations have suggested that retinoids, which are in frequent use in dermatology, can affect the connective tissue metabolism in skin and other tissues. In this study, we examined the effects of several retinoids on the metabolism of collagen by human skin fibroblasts in culture. Incubation of cultured fibroblasts with all-trans-retinoic acid or 13-cis-retinoic acid, in 10(-5) M or higher concentrations, markedly reduced the procollagen production, as measured by synthesis of radioactive hydroxyproline. The effect was selective in that little, if any, inhibition was noted in the incorporation of [3H]leucine into the noncollagenous proteins, when the cells were incubated with the retinoids in 10(-5) M concentration. Similar reduction in procollagen production was noted with retinol and retinal, whereas an aromatic analogue of retinoic acid ethyl ester (RO-10-9359) resulted in a slight increase in procollagen production in these cultures. The reduction in procollagen production by all-trans-retinoic acid was accompanied by a similar reduction in pro alpha 2(I) of type I procollagen specific messenger RNA (mRNA), as detected by dot blot and Northern blot hybridizations. Hybridizations with human fibronectin and beta-actin specific DNA probes indicated that the levels of the corresponding mRNAs were not affected by the retinoids, further suggesting selectivity in the inhibition of procollagen gene expression. Further control experiments indicated that all-trans-retinoic acid, under the culture conditions employed, did not affect the posttranslational hydroxylation of prolyl residues, the mannosylation of newly synthesized procollagen, the specific radioactivity of the intracellular prolyltransfer RNA pool, or DNA replication. All-trans-retinoic acid also elicited a reduction in trypsin-activatable collagenase, but not in the activity of prolyl hydroxylase or an elastaselike neutral protease in the fibroblast cultures. Incubation of three fibroblast lines established from human keloids with all-trans-retinoic acid or 13-cis-retinoic acid also resulted in a marked reduction in procollagen production. The results, therefore, suggest that further development of retinoids might provide a novel means of modulating collagen gene expression in patients with various diseases affecting the connective tissues.

Excess granulation tissue responses associated with isotretinoin therapy

Multiple polypoid projections of granulation tissue developed in two patients receiving isotretinoin for acne. Histological study of the lesions revealed increased amounts of non-sulphated acid mucopolysaccharides in the ground substance of the granulation tissue stroma. Complete resolution occurred following curettage with or without chemical cautery. The role of isotretinoin in the development of these lesions is discussed.