High bacterial colonization and lipase activity in microcomedones.

BACKGROUND: Although acne vulgaris has a multifactorial aetiology, comedogenesis and bacteria colonization of the pilosebaceous unit are known to play a major role in the onset of inflammatory acne lesions. However, many aspects remain poorly understood such as where and when is the early stage of the Propionibacterium acnes colonization in follicular unit? Our research aimed at providing a precise analysis of microcomedone's structure to better understand the interplay between Propionibacterium acnes and follicular units, and therefore, the role of its interplay in the formation of acne lesions. METHODS: Microcomedones were sampled using cyanoacrylate skin surface stripping (CSSS). Their morphology was investigated with multiphoton imaging and their ultrastructure with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Bacterial lipase activity in the microcomedones was quantified using a dedicated enzymatic test as well as a Fourier Transform Infra-Red (FTIR) analysis. The porphyrin produced by bacteria was analysed with HPTLC and fluorescence spectroscopy. RESULTS: The imaging analysis showed that microcomedones' structure resembles a pouch, whose interior is mostly composed of lipids with clusters of bacteria and whose outer shell is made up of corneocyte layers. The extensive bacteria colonization is clearly visible using TEM. Even after sampling, clear lipase activity was still seen in the microcomedone. A high correlation, r = .85, was observed between porphyrin content measured with HPTLC and with fluorescence spectroscopy. These observations show that microcomedones, which are generally barely visible clinically, already contain a bacterial colonization.

Long-term isotretinoin use does not cause parenchymal liver change: Ultrasonographic study in 50 patients.

The effect of isotretinoin on liver enzymes and lipid profile is reported as rare and reversible. However, possible parenchymal liver changes have not been demonstrated so far. The aim of this study was to evaluate the ultrasonography findings of the liver in patients receiving long-term isotretinoin therapy. We examined ultrasonographic findings of the liver together with serum alanin aminotransferase (ALT), aspartate aminotransferase (AST), and total cholesterol and triglyceride levels in 50 consecutive patients who have taken isotretinoin 10-40 mg daily for at least 6 months between January and December 2017. Of 50 patients examined, 40 were female, 10 were male. Mean age of the patients was 24.8 years. Five patients aged between 42 and 62 were found to have Grade 1 hepatosteatosis. Despite a moderate elevation, serum ALT, AST, and total cholesterol and triglyceride levels were in normal range in these five patients. Moreover, one patient had elevated ALT, and one another patient had elevated triglyceride level although both have normal liver ultrasonographic findings. Isotretinoin did not cause parenchymal liver changes as well as serum ALT, AST, and total cholesterol and triglyceride levels in patients who take it 10-40 mg daily for at least 6 months.

Human sebum requires de novo lipogenesis, which is increased in acne vulgaris and suppressed by acetyl-CoA carboxylase inhibition.

Sebum plays important physiological roles in human skin. Excess sebum production contributes to the pathogenesis of acne vulgaris, and suppression of sebum production reduces acne incidence and severity. We demonstrate that sebum production in humans depends on local flux through the de novo lipogenesis (DNL) pathway within the sebocyte. About 80 to 85% of sebum palmitate (16:0) and sapienate (16:1n10) were derived from DNL, based on stable isotope labeling, much higher than the contribution of DNL to triglyceride palmitate in circulation (~20%), indicating a minor contribution by nonskin sources to sebum lipids. This dependence on local sebocyte DNL was not recapitulated in two widely used animal models of sebum production, Syrian hamsters and Göttingen minipigs. Confirming the importance of DNL for human sebum production, an acetyl-CoA carboxylase inhibitor, ACCi-1, dose-dependently suppressed DNL and blocked synthesis of fatty acids, triglycerides, and wax esters but not free sterols in human sebocytes in vitro. ACCi-1 dose-dependently suppressed facial sebum excretion by ~50% (placebo adjusted) in human individuals dosed orally for 2 weeks. Sebum triglycerides, wax esters, and free fatty acids were suppressed by ~66%, whereas non-DNL-dependent lipid species, cholesterol, and squalene were not reduced, confirming selective modulation of DNL-dependent lipids. Last, individuals with acne vulgaris exhibited increased sebum production rates relative to individuals with normal skin, with >80% of palmitate and sapienate derived from DNL. These findings highlight the importance of local sebocyte DNL for human skin sebaceous gland biology and illuminate a potentially exploitable therapeutic target for the treatment of acne vulgaris.

Lactase Persistence, Milk Intake, and Adult Acne: A Mendelian Randomization Study of 20,416 Danish Adults.

Whether there is a causal relationship between milk intake and acne is unknown. We tested the hypothesis that genetically determined milk intake is associated with acne in adults using a Mendelian randomization design. LCT-13910 C/T (rs4988235) is associated with lactase persistence (TT/TC) in Northern Europeans. We investigated the association between milk intake, LCT-13910 C/T (rs4988235), and acne in 20,416 adults (age-range: 20⁻96) from The Danish General Suburban Population Study (GESUS). The adjusted observational odds ratio for acne in any milk intake vs. no milk intake was 0.93(95% confidence interval: 0.48⁻1.78) in females and 0.49(0.22⁻1.08) in males aged 20⁻39 years, and 1.15(95% confidence interval: 0.66⁻1.99) in females and 1.02(0.61⁻1.72) in males above 40 years. The unadjusted odds ratio for acne in TT+TC vs. CC was 0.84(0.43⁻1.62) in the age group 20⁻39 years, and 0.99(0.52⁻1.88) above 40 years. We did not find any observational or genetic association between milk intake and acne in our population of adults.

Rational Drug Design of Topically Administered Caspase 1 Inhibitors for the Treatment of Inflammatory Acne.

The use of an interleukin ß antibody is currently being investigated in the clinic for the treatment of acne, a dermatological disorder affecting 650M persons globally. Inhibiting the protease responsible for the cleavage of inactive pro-IL1ß into active IL-1ß, caspase-1, could be an alternative small molecule approach. This report describes the discovery of uracil 20, a potent (38 nM in THP1 cells assay) caspase-1 inhibitor for the topical treatment of inflammatory acne. The uracil series was designed according to a published caspase-1 pharmacophore model involving a reactive warhead in P1 for covalent reversible inhibition and an aryl moiety in P4 for selectivity against the apoptotic caspases. Reversibility was assessed in an enzymatic dilution assay or by using different substrate concentrations. In addition to classical structure-activity-relationship exploration, topical administration challenges such as phototoxicity, organic and aqueous solubility, chemical stability in solution, and skin metabolic stability are discussed and successfully resolved.

Decreased eicosapentaenoic acid levels in acne vulgaris reveals the presence of a proinflammatory state.

This study aimed to determine circulating levels of polyunsaturated fatty acids (PUFAs), secretory phospholipase A2 (sPLA2), lipoprotein lipase (LPL) and measure circulating protein levels of angiopoietin-like protein 3 (ANGPTL3), ANGPTL4, cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2) in patients with acne vulgaris. Serum from 21 control subjects and 31 acne vulgaris patients were evaluated for levels of arachidonic acid (AA, C20:4n- 6), dihomo-gamma-linolenic acid (DGLA, C20:3n-6), eicosapentaenoic acid (EPA, C20:5n-3) and docosahexaenoic acid (DHA, C22:6n-3). PUFA levels were determined by an optimized multiple reaction monitoring (MRM) method using ultra fast-liquid chromatography (UFLC) coupled with tandem mass spectrometry (MS/MS). Lipid profile, routine biochemical and hormone parameters were assayed by standard kit methods Serum EPA levels were significantly decreased while AA/EPA and DGLA/EPA ratio were significantly increased in acne vulgaris patients compared to controls. Serum levels of AA, DGLA and DHA showed no significant difference while activity of sPLA2 and LPL were significantly increased in acne vulgaris compared to controls. Results of this study reveal the presence of a proinflammatory state in acne vulgaris as shown by significantly decreased serum EPA levels and increased activity of sPLA2, AA/EPA and DGLA/EPA ratio. Increased LPL activity in the serum of acne vulgaris patients can be protective through its anti-dyslipidemic actions. This is the first study reporting altered EPA levels and increased sPLA2 activity in acne vulgaris and supports the use of omega-3 fatty acids as adjuvant treatment for acne patients.

Acne in adult women and the markers of peripheral 3 alpha-diol G activity.

BACKGROUND: Acne in adult women is a frequent hard-to-manage disease with many relapse cases. It mostly interferes with the quality of life of patients, bringing them major metabolic and social losses. As androgenic hormones play a very important role in the acne pathogenesis, the early diagnosis of hyperandrogenic states is very useful for the proper evaluation of each patient and for a better choice of therapeutic management. Defining a pattern for laboratory profile analysis is important for the control of relapses of acne breakouts in adult women, which lately has been the aim of many published studies. AIM: To establish the relation between 3 alpha-diol G levels and acne in female patients with normal androgenic status without menstrual dysfunctions. PATIENTS/METHODS: The evaluation of serum 3 alpha-androstanediol glucuronide levels through an enzymatic immunoassay method (Androstanediol Glucuronide ELISA Kit) for a direct quantitative measurement in 26 patients with grade II and III acne, ages ranging from 13 to 50. RESULTS: Among the analyzed patients, 83% had grade II acne, and among this total, 60% were aged 14 or over. According to age, 12 studied patients showed serum 3 alpha-diol G levels within normal range and 11 patients had increased levels. CONCLUSIONS: A total of 60% of adult women with acne present increased levels of androgens and among those with normal levels and without menstrual dysfunctions, 50% show an increase in 3 alpha-diol G. Therefore, a pharmacological approach with anti-androgenic drugs for acne therapy in most of these patients is advisable.

Serial sections of atrophic acne scars help in the interpretation of microscopic findings and the selection of good therapeutic modalities.

BACKGROUND: Acne scar causes problems cosmetically and psychologically. Although microscopic examination of acne scars is a necessity for understanding and treatment of them, and it is not easy to find a paper reporting the microscopic characterization of acne scars. OBJECTIVE: The aim of this study was to examine the microscopic findings of acne scars and to select a good therapeutic modality based on the findings. METHODS: Thirty-one atrophic scars obtained from five patients for cosmesis and 18 serial sections were made from each atrophic scar. The sections were stained with H&E, Masson-trichrome or Verhoeff van Gieson stains. Immunohistochemistry was done with antibodies against transforming growth factor-ß, metalloproteinase-1 (MMP-1), MMP-2, MMP-9 and MMP-13. The stained sections were examined under the microscope. RESULTS: The epidermis of the acne scar was characterized by keratin plugging in the hair follicle orifice (32%) and multi-channelled tracts (29%). The dermis of the acne scar had characteristics including a decrease in the dermal thickness and loss of pilosebaceous units. In addition, inflammatory cell infiltrates were seen in the dermis (77%), and insufficient dense collagen fibre deposition was found in the whole dermis (29%). Other findings such as calcium deposition and foreign body reaction were discovered. CONCLUSION: We have found the characteristics of acne scar through the serial sections of several atrophic scars, and suggest that the treatment must reflect several considerations, including the understanding of histopathological findings and the use of combination therapy.

The activity of adenosine deaminase and oxidative stress biomarkers in scraping samples of acne lesions.

BACKGROUND: Acne vulgaris is one of the most common dermatological diseases, and its pathogenesis is multifactorial. Although there are some reports about role of oxidative stress biomarkers in blood, serum, plasma in the pathogenesis of acne, there has been no report about oxidative stress biomarkers in scraping samples. For this reason, the aim of our study is to determine the role of oxidative stress biomarkers and adenosine deaminase (ADA) in scraping samples of acne lesion and to determine a possible link with the clinical severity. Fifty patients with different severity of acne vulgaris and forty healthy controls were enrolled. In both groups, ADA and oxidative stress biomarkers such as the levels of malondialdehyde (MDA), and reduced glutathione (GSH), the activities of superoxide dismutase (SOD) and catalase (CAT) in scraping samples were measured spectrophotometrically. The levels of SOD, CAT, GSH, MDA, and ADA of patients with acne were higher than the control patients (P < 0.05). ADA and MDA levels in patients with severe acne were significantly higher about two- to four-fold compared with other acne groups (P < 0.05). However, CAT, SOD, and GSH levels were lower in patients with severe acne vulgaris than the others (P < 0.05). Increased antioxidant enzyme levels of scraping samples in patients might be a local response of the organism to increased oxidative stress. Also, we believe that oxidative stress increases in parallel with the disease severity, hence antioxidant therapy may be beneficial if given in addition to the routine treatment of severe acne.

17beta-Hydroxysteroid dehydrogenase inhibitors: a patent review.

IMPORTANCE OF THE FIELD: 17beta-Hydroxysteroid dehydrogenases (17beta-HSDs) mainly catalyze the reduction of C17-ketosteroids to their corresponding hydroxylated forms as well as the reverse reaction (oxidation). Able to convert inactive or less active steroid hormones into more potent ones and vice versa, certain 17beta-HSDs play a key role, especially in the regulation of estrogen and androgen levels. The therapeutic potential of this enzyme family, especially for the treatment of breast cancer, prostate cancer, acne and osteoporosis, then stimulated the development of inhibitors of 17beta-HSDs and important progress was achieved over the last years. AREAS COVERED IN THIS REVIEW: This review article reports all patent applications related to the inhibitors of 17beta-HSDs, including some articles needed to complement the information presented. WHAT THE READER WILL GAIN: Readers will be informed about the role and function of 17beta-HSDs in the first section and about the history of inhibitor development in the second section. Furthermore, in the third and main section, the readers will learn about the structures of patented inhibitors originating from different companies and academic groups. TAKE HOME MESSAGE: The increase in the number of 17beta-HSD inhibitors reported in the last years augurs well for the future. The challenge is now to translate these results into clinical studies to allow determination of the therapeutic usefulness of 17beta-HSD inhibitors.

Selective induction of apoptosis in the hamster flank sebaceous gland organ by a topical liposome 5-alpha-reductase inhibitor: a treatment strategy for acne.

Acne is a very widespread cosmesis problem. Isotretinoin, a synthetic oral retinoid is used to treat acne, which is androgen dependent. Numerous side-effects occur from this treatment. 5-alpha-Reductase plays a critical role in normal and pathological androgen-dependent processes. We have taken the approach to develop a selective, effective, topically-applied 5-alpha-reductase inhibitor to modify unwanted or pathological processes in the pilosebaceous unit such as acne. Toward this goal, we have previously developed a selective liposome hair follicle targeting system. We demonstrate in this report that the 5-alpha-reductase inhibitor N,N-diethyl-4-methyl-3-oxo-4-aza-5alpha-androstane-17beta-carboxamide (4-MA) incorporated into liposomes induces apoptosis and inhibits growth of the dihydrotestosterone (DHT)-dependent hamster flank organ sebaceous gland. We have compared topical application of liposome 4-MA and solvent-formulated 4-MA and observed selective efficacy of topical application of liposome 4-MA by the reduction of size and induction of apoptosis only in the treated hamster flank organ. Apoptosis induced by liposome 4-MA in the treated flank organ sebaceous gland cells was observed both by assays for DNA fragments (transferase deoxytidyl uridine end labeling) and by observation of condensed and fragmented nuclei. When 4-MA was topically applied formulated in ethanol and glycerol without liposomes, the selective efficacy was lost. Liposome 4-MA did not significantly affect prostate weight, testosterone/DHT ratios or bodyweight gain compared to controls indicating safety as well as efficacy of topical application of liposome 4-MA for pathological processes such as acne.

Oxidative stress in acne vulgaris.

BACKGROUND: Acne vulgaris is one of the common dermatological diseases and its pathogenesis is multifactorial. In this study, we aimed to determine the effects of oxidative stress in acne vulgaris. MATERIALS AND METHODS: The study involved 32 patients with acne vulgaris in the patient group and 34 healthy adults in the control group. The parameters of oxidative stress such as catalase (CAT), superoxide dismutase (SOD), xanthine oxidase (XO), nitric oxide (NO) and malondialdehyde (MDA) in the venous blood of patients were measured spectrophotometrically. The values were compared with those of the control group. RESULTS: The serum levels of MDA and XO activity in the patients with acne vulgaris were significantly higher than those of the controls. A significantly lower SOD and CAT activity was found in the patient group than in the control group. Although the patient group had higher serum levels of NO than the control group, the difference was not statistically significant. CONCLUSION: These results suggest that oxidative damage may play a role in the pathogenesis of acne; therefore, significant alterations may occur in the antioxidant defence system.

The frequency of 21-alpha hydroxylase enzyme deficiency and related sex hormones in Iraqi healthy male subjects versus patients with acne vulgaris.

OBJECTIVE: To find out the frequency of nonclassical congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency among Iraqi healthy male individuals versus male patients with acne vulgaris. METHODS: This case-control study and single-center examination of hormone levels in a cohort of volunteers was conducted in the Department of Dermatology, Baghdad Teaching Hospital, and in the Physiological Chemistry Department of the College of Medicine, Baghdad University, Baghdad, Iraq, from September 2007 to February 2008. RESULTS: The frequency of 21-hydroxylase enzyme deficiency in healthy male subjects was 1:43 (2.3%), while in male patients with acne vulgaris, this was 6:43 (13.95%). Serum 17-hydroxyprogesterone (OHP) levels were statistically and significantly elevated in male patients with acne vulgaris compared with healthy male controls (p=0.020). The serum total cortisol level was significantly reduced in patients with acne vulgaris in comparison with that of healthy controls (p=0.022). CONCLUSION: These results support the necessity of inclusion of the 21-alpha hydroxylase enzyme activity (serum 17-OHP level) screening test in acne patients.

Retinoic acid 4-hydroxylase inducibility and clinical response to isotretinoin in patients with acne.

BACKGROUND: The cytochrome P450 (CYP) enzyme CYP26 (retinoic acid [RA] 4-hydroxylase) initiates the catabolism of all-trans RA (tRA) and limits the effects of tRA. The CYP26 enzyme acts specifically on tRA, but not 13-cis RA (isotretinoin), a retinoid used to treat severe acne. However, 13-cis RA can isomerize to tRA, which can then be metabolized by CYP26. OBJECTIVE: In healthy individuals, we assessed the variability of CYP26 enzymatic activity. We then investigated whether response to oral 13-cis RA among patients with acne correlates with variability in CYP26 expression. METHODS: In healthy individuals, we isolated microsomal fractions from the epidermis of keratome biopsy specimens and measured CYP26 enzymatic activity in untreated skin and skin treated with tRA. Enzymatic activity was determined based on rate of formation of 4-hydroxy RA (pg/min/mg microsomal protein). Using real-time polymerase chain reaction we quantified CYP26 messenger RNA induction after tRA application in patients with acne who responded or did not respond to one course of 13-cis RA. RESULTS: In normal-appearing skin (N = 118), CYP26 enzymatic activity was widely variable (1-180 pg/min/mg microsomal fraction; mean 42.7 +/- 3.5). Furthermore, CYP26 enzymatic activity was inducible in a dose-dependent manner in normal-appearing skin after tRA application, but not correlated with age or sex (N = 29). In patients with acne, CYP26 messenger RNA induction after 0.1% tRA application did not differ (P > .05) between patients who responded (N = 8, 587 +/- 325-fold) or did not respond (N = 8, 657 +/- 227-fold) to one course of 13-cis RA. LIMITATIONS: The small number of patients with acne treated with 13-cis RA was a major limitation. CONCLUSION: Factors other than CYP26 activity may determine response to isotretinoin in acne.

Propionibacterium acnes stimulates pro-matrix metalloproteinase-2 expression through tumor necrosis factor-alpha in human dermal fibroblasts.

Propionibacterium acnes (P. acnes) is a commensal microorganism found in sebum-rich skin and plays a role in acne inflammation by stimulating keratinocyte to produce a number of proinflammatory cytokines. However, the role of P. acnes in the dermis of acne lesions, where tissue remodeling after inflammation eventually takes place, is not known. In this study, we investigated whether P. acnes induces matrix metalloproteinase (MMP), a key enzyme involved in matrix remodeling in human dermal fibroblasts (hDF). We found that P. acnes increased expression of pro-matrix metalloproteinase (proMMP)-2 mRNA/protein in hDF, but not that of proMMP-9. Concomitantly, P. acnes induced tumor necrosis factor-alpha (TNF-alpha) mRNA/protein expression in hDF, which in turn increases both proMMP-2 mRNA and protein expression. P. acnes induced such changes through the activated NF-kappaB pathway. Doxycycline was found to inhibit the expression of proMMP-2 induced either by P. acnes or TNF-alpha. These results suggest that P. acnes stimulates hDF to produce TNF-alpha, which mediates the expression of proMMP-2 through the NF-kappaB pathway. The secretion of proMMP-2 from hDF upon P. acnes stimulation may contribute to the pathogenesis of tissue remodeling in acne skin.

The relationship between CYP17 -34T/C polymorphism and acne in Chinese subjects revealed by sequencing.

BACKGROUND: Although many arguments have been raised on the role of heredity in the etiology of acne, the relevant genetic elements in the pathogenesis of the disease are not well established. OBJECTIVE: The aim of our study was to evaluate the association between a genetic polymorphism in the promoter region of the CYP17 gene and the development of acne. METHODS: 206 acne patients and 200 controls were included in the study. A polymerase chain reaction (PCR) sequencing technique was used to reveal a CYP17 gene polymorphism in its promoter region. A chi2 test was used for data analysis. RESULTS: CYP17 -34T/C polymorphism was found and the frequency distribution of the C/C homozygotes and C allele in the male patients with severe acne (33.3 and 60.9%, respectively) were statistically significantly different from those of the control samples (18.2 and 46.6%; p < 0.05). No significant difference was observed between the female patients, mild + moderate male patients and their controls, respectively. CONCLUSION: The CYP17 -34C/C homozygote Chinese men are at a significantly increased risk of developing severe acne.

Enzymes involved in the biosynthesis of leukotriene B4 and prostaglandin E2 are active in sebaceous glands.

The expression of enzymes involved in leukotriene and prostaglandin signalling pathways, of interleukins 6 and 8 and of peroxisome proliferator-activated receptors in sebaceous glands of acne-involved facial skin was compared with those of non-involved skin of acne patients and of healthy individuals. Moreover, 5-lipoxygenase and leukotriene A(4) hydrolase were expressed at mRNA and protein levels in vivo and in SZ95 sebocytes in vitro (leukotriene A(4) hydrolase > 5-lipoxygenase), while 15-lipoxygenase-1 was only detected in cultured sebocytes. Cyclooxygenase-1 and cyclooxygenase-2 were also present. Peroxisome proliferator-activated receptors were constitutively expressed. Enhanced 5-lipoxygenase, cyclooxygenase 2 and interleukin 6 expression was detected in acne-involved facial skin. Arachidonic acid stimulated leukotriene B(4) and interleukin 6 release as well as prostaglandin E(2) biosynthesis in SZ95 sebocytes, induced abundant increase in neutral lipids and down-regulated peroxisome proliferator-activated receptor-alpha, but not receptor-gamma1 mRNA levels, which were the predominant peroxisome proliferator-activated receptor isotypes in SZ95 sebocytes. In conclusion, human sebocytes possess the enzyme machinery for functional leukotriene and prostaglandin pathways. A comprehensive link between inflammation and sebaceous lipid synthesis is provided.

Matrix metalloproteinases of epithelial origin in facial sebum of patients with acne and their regulation by isotretinoin.

Acne vulgaris is a skin disorder of the sebaceous follicles, involving hyperkeratinization and perifollicular inflammation. Matrix metalloproteinases (MMP) have a predominant role in inflammatory matrix remodeling and hyperproliferative skin disorders. We investigated the expression of MMP and tissue inhibitors of MMP (TIMP) in facial sebum specimens from acne patients, before and after treatment with isotretinoin. Gelatin zymography and Western-blot analysis revealed that sebum contains proMMP-9, which was decreased following per os or topical treatment with isotretinoin and in parallel to the clinical improvement of acne. Sebum also contains MMP-1, MMP-13, TIMP-1, and TIMP-2, as assessed by ELISA and western blot, but only MMP-13 was decreased following treatment with isotretinoin. The origin of MMP and TIMP in sebum is attributed to keratinocytes and sebocytes, since we found that HaCaT keratinocytes in culture secrete proMMP-2, proMMP-9, MMP-1, MMP-13, TIMP-1, and TIMP-2. SZ95 sebocytes in culture secreted proMMP-2 and proMMP-9, which was also confirmed by microarray analysis. Isotretinoin inhibited the arachidonic acid-induced secretion and mRNA expression of proMMP-2 and -9 in both cell types and of MMP-13 in HaCaT keratinocytes. These data indicate that MMP and TIMP of epithelial origin may be involved in acne pathogenesis, and that isotretinoin-induced reduction in MMP-9 and -13 may contribute to the therapeutic effects of the agent in acne.