Polyphenol‐rich apple extract inhibits dexamethasone‐induced sebaceous lipids production by regulating SREBP1 expression

Sebum production and excretion is a primary function of the sebaceous glands, but abnormally increased sebum production is a major cause of acne vulgaris. To identify a new candidate that regulates sebum production, we investigated the possible inhibitory effects of apple polyphenols (APP) purified from unripe apples on primary cultured human sebocytes and in patients with acne vulgaris. Dexamethasone (Dex) increased lipid synthesis and expression of the sterol response element‐binding protein 1 (SREBP 1) and its target enzymes, acetyl‐CoA carboxylase (ACC) and fatty acid synthase (FAS), in the sebocytes. However, APP inhibited Dex‐induced lipid production and expression of SREBP‐1, ACC and FAS. APP also inhibited the increase in the expression and activation of glucocorticoid receptor in the sebocytes. Taken together, these results suggest that APP may be useful to regulate sebum production and may alleviate sebum‐involved skin disease, such as acne vulgaris.     

Isotretinoin increases skin-surface levels of neutrophil gelatinase-associated lipocalin in patients treated for severe acne

Background A clear‐cut need exists for safe and effective alternatives to the use of isotretinoin in severe acne. Lack of data regarding the specifics of isotretinoin’s mechanism of action has hampered progress in this area. Recently, the protein neutrophil gelatinase‐associated lipocalin (NGAL) has been identified as a mediator of the apoptotic effect of isotretinoin on sebocytes. Objectives To establish further the clinical relevance of NGAL and to elucidate the factors that induce NGAL expression in sebocytes. Methods Methods were developed to isolate and quantify skin‐surface levels of NGAL from normal subjects and patients with acne undergoing treatment with isotretinoin. Results Patients with acne were found to have higher skin levels of NGAL compared with normal subjects. Studies in SEB‐1 sebocytes indicate that NGAL expression is increased in response to Propionibacterium acnes and interleukin (IL)‐1β. In patients, isotretinoin increases NGAL levels by 2·4‐fold on the skin surface and this increase precedes decreases in sebum and P. acnes counts. Conclusions These data support the hypothesis that NGAL is an important mediator of the early effects of isotretinoin on the sebaceous glands and provide insights into the mechanisms that regulate NGAL expression in the skin.     

TRAIL contributes to the apoptotic effect of 13-cis retinoic acid in human sebaceous gland cells

Background The full mechanism of action of isotretinoin [13‐cis retinoic acid (13‐cis RA)] in treating acne is unknown. 13‐cis RA induces key genes in sebocytes that are involved in apoptosis, including Tumor necrosis factor Related Apoptosis Inducing Ligand (TRAIL). Objectives In this study, we investigated the role of 13‐cis RA‐induced TRAIL within SEB‐1 sebocytes. Methods Using 13‐cis RA and recombinant human TRAIL (rhTRAIL) protein, we assessed induction of TRAIL and apoptosis in SEB‐1 sebocytes, normal keratinocytes and patient skin biopsies. Results Treatment with rhTRAIL protein increased TUNEL‐positive staining in SEB‐1 sebocytes. TRAIL siRNA significantly decreased the percentage of TUNEL‐positive SEB‐1 sebocytes in response to 13‐cis RA treatment. Furthermore, TRAIL expression increased in the skin of patients with acne after 1 week of isotretinoin therapy compared with baseline. TRAIL expression localized within sebaceous glands. Unlike sebocytes, TRAIL protein expression was not increased in normal human epidermal keratinocytes in response to 13‐cis RA, nor did rhTRAIL induce apoptosis in keratinocytes, suggesting that TRAIL is key in the sebocyte‐specific apoptotic effects of 13‐cis RA. Conclusions Taken together, our data suggest that TRAIL, like the neutrophil gelatinase‐associated lipocalin, is involved in mediating 13‐cis RA apoptosis of sebocytes.     

S‐allyl cysteine inhibits TNF‐α‐induced inflammation in HaCaT keratinocytes by inhibition of NF‐ κB‐dependent gene expression via sustained ERK activation

Tumor necrosis factor‐α (TNF‐α)‐induced keratinocyte inflammation plays a key role in the pathogenesis of multiple inflammatory skin diseases. Here we investigated the anti‐inflammatory effect of S‐allyl cysteine (SAC) on TNF‐α‐induced HaCaT keratinocyte cells and the mechanism behind its anti‐inflammatory potential. SAC was found to inhibit TNF‐α‐stimulated cytokine expression. Further, SAC was found to inhibit TNF‐α‐induced activation of p38, JNK and NF‐κB pathways. Interestingly, SAC was found to differentially regulate ERK MAP kinase in cells. TNF‐α‐induced transient ERK activation and SAC treatment resulted in sustained ERK activation both in the presence and absence of TNF‐α. Additionally, SAC failed to inhibit the TNF‐α‐induced expression of the pro‐inflammatory cytokines TNF‐α and IL‐1β when cells were treated with the MEK inhibitor PD98059, suggesting that the anti‐inflammatory effect of SAC is via sustained activation of the ERK pathway. Since ERK activation has been reported to negatively regulate NF‐κB‐driven gene expression and we find that SAC activates ERK and negatively regulates NF‐κB, we investigated whether there existed any crosstalk between the ERK and the NF‐κB pathways. NF‐κB‐dependent reporter assay, visualization of the nuclear translocation of NF‐κB‐p65 subunit and determination of the cellular levels of I‐κB, the inhibitor of NF‐κB, revealed that SAC inhibited TNF‐α‐induced NF‐κB activation, and PD98059 treatment reversed this effect. These results collectively suggest that SAC inhibits TNF‐α‐induced inflammation in HaCaT cells via a combined effect entailing the inhibition of the p38 and the JNK pathways and NF‐κB pathway via the sustained activation of ERK.     

Acne sans P. acnes

Acne vulgaris is a common disease that carries an enormous financial and psychosocial impact. Androgens, excessive sebum production, ductal hypercornification, changes in the microbial flora, as well as inflammation and immunological host reactions are considered the major contributors to acne pathogenesis. Despite extensive research on acne pathogenesis, the exact sequence of events and their possible mechanisms leading to the development of a microcomedone and its transformation into an inflamed lesion has remained unclear. There is a significant amount of in vitro evidence suggesting a possible pathogenetic role for Propionibacterium acnes in comedogenesis as well as inflammation in inflammatory acne. However, the microbiological data from non‐inflamed as well as inflamed acne lesions, cultured individually, do not entirely support the hypothesis that these micro‐organisms are actually responsible for their initiation. There appears to be comedones and inflamed lesions in which there is no clear evidence of Propionibacterium acnes involvement. Considering this microbiological data, alongside the in vitro evidence, we have tried to delineate the possible sequence of events and their mechanisms, leading to the development of a microcomedone and its transformation into an inflamed lesion. Based on the available literature we have analysed the evidence of both non‐inflamed as well as inflamed acne lesions occurring in the absence of Propionibacterium acnes from the pilosebaceous follicles. We propose that the development of an inflamed acne lesion depends on an imbalance between the pro‐inflammatory and anti‐inflammatory pathways rather than the incitement of inflammation by Propionibacterium acnes.     

A microbial aetiology of acne: what is the evidence?

A microbial aetiology of acne has been suggested since the beginning of the last century. There is considerable evidence, circumstantial at best, which suggests that micro‐organisms, particularly Propionibacterium acnes, are important in the pathogenesis of acne vulgaris. However, it is still unclear whether P. acnes is actually a causal agent in the development of noninflamed or inflamed acne lesions. Based on a review of the microbiological data on normal and acne‐affected skin, we propose that P. acnes neither initiates comedogenesis nor has a role in the initiation of inflammation in inflamed acne lesions.     

Differential effectiveness of selected non‐psychotropic phytocannabinoids on human sebocyte functions implicates their introduction in dry/seborrhoeic skin and acne treatment

Acne is a common skin disease characterized by elevated sebum production and inflammation of the sebaceous glands. We have previously shown that a non‐psychotropic phytocannabinoid ((–)‐cannabidiol [CBD]) exerted complex anti‐acne effects by normalizing ‘pro‐acne agents’‐induced excessive sebaceous lipid production, reducing proliferation and alleviating inflammation in human SZ95 sebocytes. Therefore, in this study we aimed to explore the putative anti‐acne effects of further non‐psychotropic phytocannabinoids ((–)‐cannabichromene [CBC], (–)‐cannabidivarin [CBDV], (–)‐cannabigerol [CBG], (–)‐cannabigerovarin [CBGV] and (–)‐Δ⁹‐tetrahydrocannabivarin [THCV]). Viability and proliferation of human SZ95 sebocytes were investigated by MTT and CyQUANT assays; cell death and lipid synthesis were monitored by DilC₁(5)‐SYTOX Green labelling and Nile Red staining, respectively. Inflammatory responses were investigated by monitoring expressions of selected cytokines upon lipopolysaccharide treatment (RT‐qPCR, ELISA). Up to 10 μm , the phytocannabinoids only negligibly altered the viability of the sebocytes, whereas high doses (≥50 μm ) induced apoptosis. Interestingly, basal sebaceous lipid synthesis was differentially modulated by the substances: CBC and THCV suppressed it, and CBDV had only minor effects, whereas CBG and CBGV increased it. Importantly, CBC, CBDV and THCV significantly reduced arachidonic acid (AA)‐induced ‘acne‐like’ lipogenesis. Moreover, THCV suppressed proliferation, and all phytocannabinoids exerted remarkable anti‐inflammatory actions. Our data suggest that CBG and CBGV may have potential in the treatment of dry‐skin syndrome, whereas CBC, CBDV and especially THCV show promise to become highly efficient, novel anti‐acne agents. Moreover, based on their remarkable anti‐inflammatory actions, phytocannabinoids could be efficient, yet safe novel tools in the management of cutaneous inflammations.     

NF‐κB is involved in inhibition of lipoxin A4 on dermal inflammation and hyperplasia induced by mezerein

Please cite this paper as: NF‐κB is involved in inhibition of lipoxin A₄ on dermal inflammation and hyperplasia induced by mezerein. Experimental Dermatology 2010; 19 : e286–e288. Abstract: The mechanisms by which lipoxin A₄ (LXA₄) inhibit skin inflammation remain unclear. In the present studies, the ear inflammatory model was induced by topical application of mezerein. Treatment of the mouse ear with LXA₄ exhibited the inhibitory effects on oedema, neutrophil infiltration, vascular permeability, expressions of interleukin (IL)‐1, IL‐6 and IL‐8 mRNA, DNA‐binding activity of nuclear factor‐κB (NF‐κB), and on dermal hyperplasia. NF‐κB reporter activities and nuclear translocations of NF‐κB p65 in cultured keratinocytes stimulated by mezerein were inhibited by pretreatment of the cells with LXA₄. LXA₄ reduced degradation, but not phosphorylation of IκBα in cultured keratinocytes stimulated by mezerein, suggesting that LXA₄‐attenuated IκBα degradation may restore the mezerein‐blocked inhibitory effects of IκB on nuclear translocation and DNA‐binding activity of NF‐κB. Our results demonstrated that LXA₄ displays the anti‐inflammatory and anti‐proliferative role on ear inflammatory model induced by mezerein and these effects were related with downregulation of DNA‐binding activity of NF‐κB.     

SIG1459: A novel phytyl‐cysteine derived TLR2 modulator with in vitro and clinical anti‐acne activity

Cutibacterium (formerly Propionibacterium acnes) is a major contributor to the pathogenesis of acne. C. acnes initiates an innate immune response in keratinocytes via recognition and activation of toll‐like receptor‐2 (TLR2), a key step in comedogenesis. Tetramethyl‐hexadecenyl‐cysteine‐formylprolinate (SIG1459), a novel anti‐acne isoprenylcysteine (IPC) small molecule, is shown in this study to have direct antibacterial activity and inhibit TLR2 inflammatory signalling. In vitro antibacterial activity of SIG1459 against C. acnes was established demonstrating minimal inhibitory concentration (MIC = 8.5 μmol\L), minimal bactericidal concentration (MBC = 16.1 μmol\L) and minimal biofilm eradication concentration (MBEC = 12.5 μmol\L). To assess SIG1459's anti‐inflammatory activity, human keratinocytes were exposed to C. acnes and different TLR2 ligands (peptidoglycan, FSL‐1, Pam3CSK4) that induce pro‐inflammatory cytokine IL‐8 and IL‐1α production. Results demonstrate SIG1459 inhibits TLR2‐induced IL‐8 release from TLR2/TLR2 (IC₅₀ = 0.086 μmol\L), TLR2/6 (IC₅₀ = 0.209 μmol\L) and IL‐1α from TLR2/TLR2 (IC₅₀ = 0.050 μmol\L). To assess the safety and in vivo anti‐acne activity of SIG1459, a vehicle controlled clinical study was conducted applying 1% SIG1459 topically (n = 35 subjects) in a head‐to‐head comparison against 3% BPO (n = 15 subjects). Utilizing the Investigator Global Assessment scale for acne as primary endpoint, results demonstrate 1% SIG1459 significantly outperformed 3% BPO over 8 weeks, resulting in 79% improvement as compared to 56% for BPO. Additionally, 1% SIG1459 was well tolerated. Thus, SIG1459 and phytyl IPC compounds represent a novel anti‐acne technology that provides a safe dual modulating benefit by killing C. acnes and reducing the inflammation it triggers via TLR2 signalling.     

Heat‐killed Propionibacterium acnes is capable of inducing inflammatory responses in skin

Abstract: The etiology of acne is a complex process, and acne is one of the most common skin disorders affecting millions of people. The pathogenesis of acne is closely associated with the bacterium, Propionibacterium acnes which was previously known as Corynebacterium parvum. Both viable and non‐viable P. acnes/C. parvum have been shown to induce an immunostimulatory effect in vivo, suggesting that even dead bacteria continue to activate an inflammatory response. Acne treatments with lasers or devices, induce a bactericidal effect through heat generation which may not address the immunogenic activity of P. acnes and the resulting acne inflammation. Therefore, we sought to determine whether killed P. acnes is capable of inducing an inflammatory response and therefore could be a contributing factor in acne. Direct heat treatment of P. acnes cultures with temperatures ranging from 50°C to 80°C reduced P. acnes viability. Both viable and heat‐killed P. acnes activated the p38 MAP kinase and its downstream substrate Hsp27. Stimulating keratinocytes with normal and heat‐inactivated P. acnes resulted in an induction of proinflammatory nitric oxide and IL‐8 production. Thus killed P. acnes is capable of inducing inflammation in skin suggesting that therapies that have both bactericidal and anti‐inflammatory effects may result in a more effective treatment of patients with acne than treatments that are bactericidal alone.     

Heterogeneity and antibiotic resistance in Propionibacterium acnes isolates and its therapeutic implications: blurring the lines between commensal and pathogenic phylotypes

Acne vulgaris is a multifactorial skin disease associated with the colonization of Propionibacterium acnes. Antibiotics are a mainstay of treatment for acne, yet the emergence of resistance against the currently approved antibiotics is a serious concern. In this case report, a slow responder had multiple Propionibacterium acnes isolates with varied levels of sensitivity to the conventional antibiotics. The bacterial isolates obtained from acne samples collected from the patient were analyzed for phylogeny, and was found to be largely restricted to two different lineage patterns. Propionibacterium acnes phylotype IA1, which is considered to be pathogenic, displayed clindamycin sensitivity, but phylotype IB, which is associated with commensals, exhibited high clindamycin resistance. Sensitivity analysis revealed uniform resistance to macrolides, but susceptibility to tetracycline and nadifloxacin. These results implicate Propionibacterium acnes in the pathophysiology of acne vulgaris, although the lines between commensal and pathological phylotypes may be blurred. Switching the patient to a combination of minocycline and nadifloxacin resulted in a significant improvement in the clinical lesions. Such a science‐driven judicious selection of antibiotics can minimize the probability of development of resistance, and might be the way forward in the treatment of acne.     

The use of oral antibiotics in treating acne vulgaris: a new approach

Although acne is not an infectious disease, oral antibiotics have remained a mainstay of treatment over the last 40 years. The anti‐inflammatory properties of oral antibiotics, particularly the tetracyclines, are efficacious in treating inflammatory acne lesions. Common prescribing practices in Dermatology exert significant selection pressure on bacteria, contributing to the development of antibiotic resistance. Antibiotic use for acne not only promotes resistance in Propionibacterium acnes, but also affects other host bacteria with pathogenic potential. This review will summarize the commonly used treatments for acne vulgaris, and how they should be combined as rational treatment. The indications for using oral antibiotics in acne will be highlighted. Strategies described in the literature to conserve the utility of oral antibiotics will be summarized. These include limiting the duration of antibiotic therapy, concomitant use of a topical non‐antibiotic agent, use of subantimicrobial dose doxycycline, and the introduction of topical dapsone.     

Acne,quorum sensing and danger

Propionibacterium acnes is a ubiquitous skin commensal bacterium, which is normally well tolerated by the immune system in healthy human skin. However, there is increasing evidence to suggest a pivotal role for P. acnes in the inflammatory process underlying the acne pathogenesis. With its features of inflammation and pustulation, acne vulgaris resembles the skin's normal reaction to bacterial pathogens. P. acnes flourishes when sebum production increases in the follicles. Bacteria may undergo behavioural changes based on the surrounding bacterial population, a process called quorum sensing (QS). Evidence from in vitro studies suggests that QS enables P. acnes to upregulate its hydrolysis of sebum triglycerides by its bacterial lipases, secreting free fatty acids (FFAs) such as oleic, palmitic and lauric acids. These FFAs act as danger‐associated molecular patterns (DAMPs), and activate Toll‐like receptor (TLR)2 and TLR4, leading to selective T‐helper (Th)‐driven immunity, with subsequent expression of Th1/Th17‐associated inflammatory cytokines. To our knowledge, there is currently no explanation as to what determines the shift of recognition by the immune system of P. acnes from being symbiotic to pathogenic. We present a novel hypothesis based on the essence of QS and DAMPs. P. acnes sends no or only ‘safety’ signals when present in ‘controlled’ quantities under commensal conditions, but becomes pathogenic and sends ‘danger’ signals via QS in the form of excess FFA production, which stimulates TLR2 and TLR4 as the bacterial population flourishes.     

Single nucleotide polymorphisms of toll‐like receptor‐4 protect against acne conglobata

Background Former studies have shown that Propionibacterium acnes may stimulate expression of toll‐like receptor 4 (TLR4) in keratinocytes of patients with acne vulgaris. Objective To investigate the impact of single nucleotide polumorphisms (SNPs) of the TLR4 gene in acne vulgaris. Methods Genomic DNA was isolated from 191 patients with acne vulgaris and 75 healthy controls. Asp299Gly and Thr399Ile SNPs were defined after cutting of the PCR products by restriction enzymes. Sebum of lesions was cultured for P. acnes. Results No differences in SNP allele frequencies were found between patients and healthy controls. 46.5% of carriers of wild‐type alleles were suffering from acne conglobata compared with 28.6% of carriers of SNP alleles (P = 0.040). After adjusting for gender, family history of acnes, intake of any therapy and skin isolation of P. acnes, carriage of TLR4 gene SNPs was the only independent variable linked with a protective role against acne conglobata (OR = 0.269, P = 0.014). No differences were found in the amount of pro‐inflammatory cytokines released by peripheral blood mononuclear cells isolated from patients with acne conglobata carrying only wild‐type alleles and SNP alleles. Conclusions Carriage of gene SNPs is protective against the development of acne conglobata even in the presence of P. acnes.     

Interleukin‐10 secretion from CD14+ peripheral blood mononuclear cells is downregulated in patients with acne vulgaris

Background Acne is a common chronic inflammatory dermatosis of the pilosebaceous unit. It is characterized by seborrhoea, comedone formation and an inflammatory response consistent with defective cellular immunity to Propionibacterium acnes. Objectives The objective of this study was to investigate the immune reactivity of patients with acne compared with healthy controls by examining the response of peripheral blood mononuclear cells (PBMCs) to stimulation with P. acnes. Particular focus was placed upon measuring the production of interleukin (IL)‐10, which has an established immunoregulatory role. Patients and methods Venous blood was collected from 47 patients with acne and 40 age‐ and sex‐matched healthy controls with no prior history of acne. PBMCs were cultured and their cytokine response to P. acnes investigated. Results Proinflammatory IL‐8 and tumour necrosis factor (TNF)‐α secretion from PBMCs was higher in patients with acne when stimulated with P. acnes. In contrast, a statistically significant reduction in PBMC secretion of anti‐inflammatory IL‐10 in patients with acne was identified. The impaired production of IL‐10 by PBMCs from patients with acne was confined to CD14+ cells presumed to be monocytes. The ability of CD14 cells from patients with acne to phagocytose P. acnes bacteria was also observed to be defective but the addition of exogenous IL‐10 to PBMC cultures restored phagocytic activity. Conclusions These data suggest that patients with acne have a proinflammatory cytokine milieu and crucially are unable to contain early inflammatory changes due to a specific defect in immunosurveillance, namely low monocyte IL‐10 production. Our observations raise the possibility that acne therapeutics might profitably target IL‐10 both as a regulator of proinflammatory cytokines and in augmenting the CD14+ cell phagocytic response.     

The potential of probiotics for treating acne vulgaris: A review of literature on acne and microbiota

Acne is known as a chronic inflammatory skin disease with sever adverse effects on quality of life in the patients. The increasing resistance to antibiotics has decreased their effectiveness in treating acne. As viable microbial dietary supplements, probiotics provide health benefits through fighting pathogens and maintaining the homeostasis of the gut and skin microbiome. The present article reviewed the potential of probiotics as beneficial microorganisms for treating acne vulgaris. This review of literature was conducted through a bibliographic search of popular databases, including Science Direct, PubMed, Scielo and Medline, using keywords such as probiotics, prebiotics, synbiotics, microbiome, and acne vulgaris to determine potential applications of these beneficial microbiomes in treating acne vulgaris. Acne lesions are associated with increases in proportion of Propionibacterium acnes as a skin commensal bacterium. The environmental studies showed inhibitory effects of probiotics on P. acnes, mediating by antibacterial proteins and bacteriocin‐like inhibitory substances, and their immunomodulatory effects onkeratinocytes and epithelial cells. Probiotics were also found to inhibit cytokine IL‐8 in epithelial cells and keratinocytes, suggesting immunomodulatory activities. Moreover, glycerol fermentation by Staphylococcus epidermidis was found to be a natural skin defense against acne and an overgrowth inhibitor of P. acnes. As an antimicrobial agent in lotions and cosmetic formulations, Lactococcus sp. can decrease the inflammatory mediators that are produced by P. acnes and cause vasodilation, edema, mast cell degranulation and TNF‐alpha release. Oral administration of probiotics was found to constitute an adjuvant therapy to conventional modalities for treating mild‐to‐moderate acne vulgaris.     

Shiunko and Chuoko,topical Kampo medicines,inhibit the expression of gehA encoding the extracellular lipase in Cutibacterium acnes

Antimicrobial agents have been used for eradication of Cutibacterium (formerly Propionibacterium) acnes that is an exacerbation factor of the skin disease acne vulgaris. However, the use of antibiotics is associated with an increased risk of promoting the emergence of resistant bacteria and leading to skin dysbiosis. Traditional Japanese Kampo medicines, such as Keigairengyoto, are used to treat acne. However, there is incomplete understanding regarding their functional mechanism in treatment of acne. In this study, we examined the antimicrobial and anti‐lipase activity of the Kampo medicines used empirically for acne treatment. Three oral medicines, Keigairengyoto, Seijoboufuto and Jumihaidokuto, were found to inhibit the growth of C. acnes and decrease the lipase activity. Especially, Keigairengyoto caused remarkable decrease of bacterial lipase activity. Furthermore, topical medicines such as Shiunko and Chuoko significantly decreased the lipase activity in a dose‐dependent manner, without inhibiting C. acnes growth. The topical medicines were found to inhibit the expression of gehA, which codes for extracellular lipase. Our results indicate that Shiunko and Chuoko have potential as effective acne therapeutic agents, especially because they do not promote the emergence of antimicrobial‐resistant bacteria and skin dysbiosis.