NLRP3 inflammasome activation and NETosis positively regulate each other and exacerbate proinflammatory responses: implications of NETosis inhibition for acne skin inflammation treatment

Inflammasomes are multiprotein complexes involved in the host immune response to pathogen infections. Thus, inflammasomes participate in many conditions, such as acne. Recently, it was shown that NETosis, a type of neutrophil cell death, is induced by bacterial infection and is involved in inflammatory diseases such as delayed wound healing in patients with diabetes. However, the relationship between inflammasomes and NETosis in the pathogenesis of inflammatory diseases has not been well studied. In this study, we determined whether NETosis is induced in P. acnes-induced skin inflammation and whether activation of the nucleotide-binding domain, leucine-rich family, and pyrin domain-containing-3 (NLRP3) inflammasome is one of the key factors involved in NETosis induction in a mouse model of acne skin inflammation. We found that NETosis was induced in P. acnes-induced skin inflammation in mice and that inhibition of NETosis ameliorated P. acnes-induced skin inflammation. In addition, our results demonstrated that inhibiting inflammasome activation could suppress NETosis induction in mouse skin. These results indicate that inflammasomes and NETosis can interact with each other to induce P. acnes-induced skin inflammation and suggest that targeting NETosis could be a potential treatment for inflammasome-mediated diseases as well as NETosis-related diseases.

Integrative bioinformatics and experimental validation of hub genetic markers in acne vulgaris: Toward personalized diagnostic and therapeutic strategies

BACKGROUND

Acne vulgaris is a widespread chronic inflammatory dermatological condition. The precise molecular and genetic mechanisms of its pathogenesis remain incompletely understood. This research synthesizes existing databases, targeting a comprehensive exploration of core genetic markers.

METHODS

Gene expression datasets (GSE6475, GSE108110, and GSE53795) were retrieved from the GEO. Differentially expressed genes (DEGs) were identified using the limma package. Enrichment analyses were conducted using GSVA for pathway assessment and clusterProfiler for GO and KEGG analyses. PPI networks and immune cell infiltration were analyzed using the STRING database and ssGSEA, respectively. We investigated the correlation between hub gene biomarkers and immune cell infiltration using Spearman's rank analysis. ROC curve analysis validated the hub genes' diagnostic accuracy. miRNet, TarBase v8.0, and ChEA3 identified miRNA/transcription factor-gene interactions, while DrugBank delineated drug-gene interactions. Experiments utilized HaCaT cells stimulated with Propionibacterium acnes, treated with retinoic acid and methotrexate, and evaluated using RT-qPCR, ELISA, western blot, lentiviral transduction, CCK-8, wound-healing, and transwell assays.

RESULTS

There were 104 genes with consistent differences across the three datasets of paired acne and normal skin. Functional analyses emphasized the significant enrichment of these DEGs in immune-related pathways. PPI network analysis pinpointed hub genes PTPRC, CXCL8, ITGB2, and MMP9 as central players in acne pathogenesis. Elevated levels of specific immune cell infiltration in acne lesions corroborated the inflammatory nature of the disease. ROC curve analysis identified the acne diagnostic potential of four hub genes. Key miRNAs, particularly hsa-mir-124-3p, and central transcription factors like TFEC were noted as significant regulators. In vitro validation using HaCaT cells confirmed the upregulation of hub genes following Propionibacterium acnes exposure, while CXCL8 knockdown reduced pro-inflammatory cytokines, cell proliferation, and migration. DrugBank insights led to the exploration of retinoic acid and methotrexate, both of which mitigated gene expression upsurge and inflammatory mediator secretion.

CONCLUSION

This comprehensive study elucidated pivotal genes associated with acne pathogenesis, notably PTPRC, CXCL8, ITGB2, and MMP9. The findings underscore potential biomarkers, therapeutic targets, and the therapeutic potential of agents like retinoic acid and methotrexate. The congruence between bioinformatics and experimental validations suggests promising avenues for personalized acne treatments.

YTHDC1-Modified m6A Methylation of Hsa_circ_0102678 Promotes Keratinocyte Inflammation Induced by Cutibacterium acnes Biofilm through Regulating miR-146a/TRAF6 and IRAK1 Axis

INTRODUCTION

CircRNAs are closely related to many human diseases; however, their role in acne remains unclear. This study aimed to determine the role of hsa_circ_0102678 in regulating inflammation of acne.

METHODS

First, microarray analysis was performed to study the expression of circRNAs in acne. Subsequently, RNase R digestion assay and fluorescence in situ hybridization assay were utilized to confirm the characteristics of hsa_circ_0102678. Finally, qRT-PCR, Western blotting analysis, immunoprecipitation, luciferase reporter assay, circRNA probe pull-down assay, biotin-labeled miRNA pull-down assay, RNA immunoprecipitation assay, and m6A dot blot assay were utilized to reveal the functional roles of hsa_circ_0102678 on inflammation induced by C. acnes biofilm in human primary keratinocytes.

RESULTS

Our investigations showed that the expression of hsa_circ_0102678 was significantly decreased in acne tissues, and hsa_circ_0102678 was a type of circRNAs, which was mainly localized in the cytoplasm of primary human keratinocytes. Moreover, hsa_circ_0102678 remarkably affected the expression of IL-8, IL-6, and TNF-α, which induced by C. acnes biofilm. Importantly, mechanistic studies indicated that the YTHDC1 could bind directly to hsa_circ_0102678 and promote the export of N6-methyladenosine-modified hsa_circ_0102678 to the cytoplasm. Besides, hsa_circ_0102678 could bind to miR-146a and sponge miR-146a to promote the expression of IRAK1 and TRAF6.

CONCLUSION

Our findings revealed a previously unknown process by which hsa_circ_0102678 promoted keratinocyte inflammation induced by C. acnes biofilm via regulating miR-146a/TRAF6 and IRAK1 axis.

The Pathogenesis and Management of Acne-Induced Post-inflammatory Hyperpigmentation

Acne vulgaris is a common inflammatory disease. Among patients with darker skin phototypes (Fitzpatrick III-VI), the inflammatory processes of acne stimulate excess melanogenesis and abnormal melanin deposition, leading to pigmentary sequelae known as post-inflammatory hyperpigmentation and post-inflammatory erythema in all skin tones, although post-inflammatory hyperpigmentation is more common in darker skin and post-inflammatory erythema in lighter skin. These pigmentary alterations can be long lasting and are often more distressing to patients than the active acne lesions. This article discusses what is known about acne-related pigmentation, much of which is extrapolated from general study of nonspecific pigment deposition. Because dyspigmentation poses both a significant clinical concern to patients and a therapeutic challenge to clinicians, we formed a working group consisting of pigmentary experts with the aim of increasing awareness and education of acne-related pigmentary sequelae.

The Skin Microbiome: A New Actor in Inflammatory Acne

Our understanding of the role of Cutibacterium acnes in the pathophysiology of acne has recently undergone a paradigm shift: rather than C. acnes hyperproliferation, it is the loss of balance between the different C. acnes phylotypes, together with a dysbiosis of the skin microbiome, which results in acne development. The loss of diversity of C. acnes phylotypes acts as a trigger for innate immune system activation, leading to cutaneous inflammation. A predominance of C. acnes phylotype IA₁ has been observed, with a more virulent profile in acne than in normal skin. Other bacteria, mainly Staphylococcus epidermis, are also implicated in acne. S. epidermidis and C. acnes interact and are critical for the regulation of skin homeostasis. Recent studies also showed that the gut microbiome is involved in acne, through interactions with the skin microbiome. As commonly used topical and systemic antibiotics induce cutaneous dysbiosis, our new understanding of acne pathophysiology has prompted a change in direction for acne treatment. In the future, the development of individualized acne therapies will allow targeting of the pathogenic strains, leaving the commensal strains intact. Such alternative treatments, involving modifications of the microbiome, will form the next generation of ‘ecobiological’ anti-inflammatory treatments.

Omega-3 Versus Omega-6 Polyunsaturated Fatty Acids in the Prevention and Treatment of Inflammatory Skin Diseases

Omega-3 (ω-3) and omega-6 (ω-6) polyunsaturated fatty acids (PUFAs) are nowadays desirable components of oils with special dietary and functional properties. Their therapeutic and health-promoting effects have already been established in various chronic inflammatory and autoimmune diseases through various mechanisms, including modifications in cell membrane lipid composition, gene expression, cellular metabolism, and signal transduction. The application of ω-3 and ω-6 PUFAs in most common skin diseases has been examined in numerous studies, but their results and conclusions were mostly opposing and inconclusive. It seems that combined ω-6, gamma-linolenic acid (GLA), and ω-3 long-chain PUFAs supplementation exhibits the highest potential in diminishing inflammatory processes, which could be beneficial for the management of inflammatory skin diseases, such as atopic dermatitis, psoriasis, and acne. Due to significant population and individually-based genetic variations that impact PUFAs metabolism and associated metabolites, gene expression, and subsequent inflammatory responses, at this point, we could not recommend strict dietary and supplementation strategies for disease prevention and treatment that will be appropriate for all. Well-balanced nutrition and additional anti-inflammatory PUFA-based supplementation should be encouraged in a targeted manner for individuals in need to provide better management of skin diseases but, most importantly, to maintain and improve overall skin health.

The impact of recent advances in lipidomics and redox lipidomics on dermatological research

Dermatological research is a major beneficiary of the rapidly developing advances in lipid analytic technology and of bioinformatic tools which help to decipher and interpret the accumulating big lipid data. At its interface with the environment, the epidermis develops a blend of lipids that constitutes the epidermal lipid barrier, essential for the protection from water loss and entry of dangerous noxae. Apart from their structural role in the barrier, novel intra- and inter-cellular signaling functions of lipids and their oxidation products have been uncovered in most cutaneous cell types over the last decades, and the discovery rate has been boosted by the advent of high resolution and -throughput mass spectrometric techniques. Our understanding of epidermal development has benefited from studies on fetal surface lipids, which appear to signal for adaptation to desiccation post partum, and from studies on the dynamics of epidermal lipids during adjustment to the atmosphere in the first months of life. At birth, external insults begin to challenge the skin and its lipids, and recent years have yielded ample insights into the dynamics of lipid synthesis and -oxdiation after UV exposure, and upon contact with sensitizers and irritants. Psoriasis and atopic dermatitis are the most common chronic inflammatory skin diseases, affecting at least 3% and 7% of the global population, respectively. Consequently, novel (redox-) lipidomic techniques have been applied to study systemic and topical lipid abnormalities in patient cohorts. These studies have refined the knowledge on eicosanoid signaling in both diseases, and have identified novel biomarkers and potential disease mediators, such as lipid antigens recognized by psoriatic T cells, as well as ceramide species, which specifically correlate with atopic dermatitis severity. Both biomarkers have yielded novel mechanistic insights. Finally, the technological progress has enabled studies to be performed that have monitored the consequences of diet, lifestyle, therapy and cosmetic intervention on the skin lipidome, highlighting the translational potential of (redox-) lipidomics in dermatology.

A Subset of Type I Conventional Dendritic Cells Controls Cutaneous Bacterial Infections through VEGFα-Mediated Recruitment of Neutrophils

Skin conventional dendritic cells (cDCs) exist as two distinct subsets, cDC1s and cDC2s, which maintain the balance of immunity to pathogens and tolerance to self and microbiota. Here, we examined the roles of dermal cDC1s and cDC2s during bacterial infection, notably Propionibacterium acnes (P. acnes). cDC1s, but not cDC2s, regulated the magnitude of the immune response to P. acnes in the murine dermis by controlling neutrophil recruitment to the inflamed site and survival and function therein. Single-cell mRNA sequencing revealed that this regulation relied on secretion of the cytokine vascular endothelial growth factor α (VEGF-α) by a minor subset of activated EpCAM+CD59+Ly-6D+ cDC1s. Neutrophil recruitment by dermal cDC1s was also observed during S. aureus, bacillus Calmette-Guérin (BCG), or E. coli infection, as well as in a model of bacterial insult in human skin. Thus, skin cDC1s are essential regulators of the innate response in cutaneous immunity and have roles beyond classical antigen presentation.

Values of the systemic immunity in patients suffering from acne with different clinical course

OBJECTIVE

Introduction: Acne is chronic recurrent dermatosis, one of the essential skin inflammation in the structure of dermatological pathology, especially in young people of working age, often caused by persistent cicatricial changes in the skin, and affecting negatively the psychoemotional state of patients, their quality of life and working capacity. It has been established by today that the pathogenesis acne is complex and multifactorial, and the changes of immune reactivity of the organism play an important role in its clinical course development. The aim of the article is to determine and analyze the values of the systemic immunity in patients suffering from acne with different clinical course.

PATIENTS AND METHODS

Materials and methods: 128 patients with acne aged from 18 to 35, among which 74 women (57,8 %) and 54 men (42,2 %) were observed. According to the clinical criteria, 26 patients (20,31%) were diagnosed with comedonal form of acne, 40 patients (31.25%) had papules, 10 people (7.81%) -papular-pustular acne, 29 of the observed (22.65%) had pustules, 9 patients (7.03%) suffered from acne conglobata, and 14 patients (10.94%) were diagnosed with post-acne. The control group consisted of 34 practically healthy people (donors) of the same age.

RESULTS

Results: Consequently, most of the patients with acne had varying degrees of changes in rates of systemic immunity - the likely reduction in relative and absolute number of total lymphocytes, T-lymphocytes and their subpopulations against the growing number of B lymphocytes and the level of IgM and IgG, which generally indicates the formation in these patients secondary immunodeficiency state of T-link intensified by activation of humoral immunity in response to the development of skin inflammation. The most significant changes in rates of systemic immunity with the depletion of T-cell immunity were found in patients with papular-pustular and pustular acne, and still more significant - in patients with acne conglobate, which justifies differentiated treatment by immunomotropic drugs for these patients.

CONCLUSION

Conclusion: In patients with acne, changes in systemic immunity indexes that indicate the formation of secondary immunodeficiency state T-cell link, amid an adequate humoral immunity have been found. Relationship between the causes of changes of systemic immunity has been established.

A dermatologic perspective on autoinflammatory diseases

Autoinflammatory diseases (AIDs) encompass a heterogeneous group of disorders pathogenetically related to an abnormal activation of the innate immunity and clinically characterised by aseptic inflammation in the affected organs in the absence of high titer of circulating autoantibodies or autoreactive T cells. In classic monogenic AIDs, the skin is frequently involved with a wide range of cutaneous lesions. Monogenic AIDs result from different mutations in a single gene, which regulates the innate immunity. These mutations cause an uncontrolled activation of the inflammasome, leading to an overexpression of interleukin (IL)- 1β. IL-1β is the pivotal cytokine which is responsible for the exaggerated production of cytokines and chemokines that induce the recruitment of neutrophils, key cells in autoinflammation. Paradigmatic autoinflammatory forms are the cryopyrin-associated periodic syndromes (CAPS), whose skin involvement consists of urticarial lesions. Similar IL-1β-mediated autoinflammatory pathomechanisms also occur in deficiency of IL-1 receptor antagonist (DIRA) and deficiency of IL-36 receptor antagonist (DITRA), whose cutaneous appearance is characterised by pustular lesions, as well as in pyogenic arthritis, pyoderma gangrenosum and acne (PAPA) syndrome. Pyoderma gangrenosum, which is the cutaneous hallmark of the PAPA syndrome, is a prototypic neutrophil-mediated skin disease, manifesting as single or multiple ulcers with undermined, raised erythematous to violaceous borders. This review is focused on the CAPS, DIRA/DITRA and PAPA syndromes with emphasis on their cutaneous manifestations, as well as their histology and pathophysiology.

PAPA, PASH and PAPASH Syndromes: Pathophysiology, Presentation and Treatment

Pyoderma gangrenosum (PG) is a neutrophilic dermatosis usually manifesting as skin ulcers with undermined erythematous-violaceous borders. It may be isolated, associated with systemic conditions or occurring in the context of autoinflammatory syndromes such as PAPA (pyogenic arthritis, PG and acne), PASH (PG, acne and suppurative hidradenitis) or PAPASH (pyogenic arthritis, acne, PG and suppurative hidradenitis). From a physiopathological point of view, all these conditions share common mechanisms consisting of over-activation of the innate immune system leading to increased production of the interleukin (IL)-1 family and 'sterile' neutrophil-rich cutaneous inflammation. From a genetic point of view, a number of mutations affecting the proteins of the inflammasome complex (the molecular platform responsible for triggering autoinflammation) or the proteins that regulate inflammasome function have been described in these disorders. As these debilitating entities are all associated with the over-expression of IL-1 and tumour necrosis factor (TNF)-α, biological drugs specifically targeting these cytokines are currently the most effective treatments but, given the emerging role of IL-17 in the pathogenesis of these syndromes, IL-17 antagonists may represent the future management of these conditions.

Evolution of some indicators of systemic immunity in patients with acne while using laser therapy

INTRODUCTION

One of the important problems in modern dermatology is to improve treatment efficiency of acne being a common cause for cicatricial skin changes, loss of performance capability and social activity and negatively affects the psycho-emotional state of patients and their quality of life. The topicality of the disease is due to the high degree of its proliferation, chronic and recurrent course, and resistance to existing therapies. Reducing the effectiveness of skin diseases treatment, including that of acne, at present, is associated with developing resistance to drugs, which causes the use of non-drug methods in dermatology nowadays, including low-intensity laser therapy. Objective - to determine evolution of the systemic immunity indices in patients with acne with different degrees of severity in the course of a standard and comprehensive treatment by laser therapy.

MATERIALS AND METHODS

We observed 77 patients with acne aged 18-25 years; 32 of them received standard therapy, other 45 patients were additionally prescribed combined (superficial venous and external) laser therapy. We determined the indices of all patients' systemic immunity using well-known techniques.

RESULTS

It has been established, that using laser therapy in comprehensive treatment of patients with acne promotes the normalization or a tendency to normalization of the systemic immunity and phagocytosis with significant difference between the indices of the individuals who received a standard therapy alone.

Monogenic Auto-inflammatory Syndromes: A Review of the Literature

Auto-inflammatory syndromes are a new group of distinct hereditable disorders characterized by episodes of seemingly unprovoked inflammation (most commonly in skin, joints, gut, and eye), the absence of a high titer of auto-antibodies or auto-reactive T cells, and an inborn error of innate immunity. A narrative literature review was carried out of studies related to auto-inflammatory syndromes to discuss the pathogenesis and clinical manifestation of these syndromes. This review showed that the main monogenic auto-inflammatory syndromes are familial Mediterranean fever (FMF), mevalonate kinase deficiency (MKD), Blau syndrome, TNF receptor-associated periodic syndrome (TRAPS), cryopyrin-associated periodic syndrome (CAPS), and pyogenic arthritis with pyoderma gangrenosum and acne (PAPA). The data suggest that correct diagnosis and treatment of monogenic auto-inflammatory diseases relies on the physicians' awareness. Therefore, understanding of the underlying pathogenic mechanisms of auto-inflammatory syndromes, and especially the fact that these disorders are mediated by IL-1 secretion stimulated by monocytes and macrophages, facilitated significant progress in patient management.

Histopathological and clinical evaluation of papulopustular lesions in Behçet's disease

OBJECTIVES

Behçet's disease (BD) is a chronic inflammatory disorder characterised by aphthous stomatitis, genital ulcerations, erythema nodosum-like manifestations and papulopustular lesions. While a neutrophilic vasculitis accompanies most skin lesions it is usually regarded that the papulopustular lesions in BD are similar to acne vulgaris (AV). The aim of our current study was to further assess the clinical and histopathological features of papulopustular lesions in BD and how these features compared to those of AV.

METHODS

To analyse the histopathological features of BD and AV, 89 punch biopsies were taken from 58 BD (52 male, 6 female) and 31 AV patients (26 male, 5 female). Sections were evaluated in a blind manner by two different pathologists. A dermatologist who was blind to the patients' diagnosis counted the number of papules, pustules, comedones, folliculitis, cysts and nodules on the face, chest, back, upper and lower extremities.

RESULTS

The number of papules, pustules and comedones was higher on the face in the AV group, whereas in the BD group, both number of papules and folliculitis on the back and that of folliculitis were higher on the lower extremities in the AV group. With the exception of comedone formation, which was more frequent among the AV patients [20/31 (64.5%) vs. 23/58 (39.6%), p=0.025] the presence of suppurative folliculitis/perifolliculitis, intrafollicular abscess formation, leukocytoclastic vasculitis or microorganisms were not useful in differentiating BD from AV. However, the interobserver agreement for histologic assessment was low. Kappa was 0.17 for suppurative foliculitis/perifol¬liculitis; 0.39 for intrafollicular abscess formation; 0.51 for leukocytoclastic vasculitis.

CONCLUSIONS

In the BD group, although the inflammatory lesions located on the face were less than those in the AV group inflammatory lesions such as folliculitis on the legs were only seen, again in the BD group. The papulopustular lesions of BD could not be distinguished from AV by histology. Some of this might be due to high interobsever variation in interpretation. Acne is an inherent manifestation of BD.

Suppression of Propionibacterium acnes Infection and the Associated Inflammatory Response by the Antimicrobial Peptide P5 in Mice

The cutaneous inflammation associated with acne vulgaris is caused by the anaerobic bacterium Propionibacterium acnes through activation of the innate immune system in the skin. Current standard treatments for acne have limitations that include adverse effects and poor efficacy in many patients, making development of a more effective therapy highly desirable. In the present study, we demonstrate the protective effects of a novel customized α-helical cationic peptide, P5, against P. acnes-induced inflammatory responses in vitro and in vivo. Application of P5 significantly reduced expression of two inflammatory cytokines IL-8 and TNF-α in P. acnes-treated primary human keratinocytes, where P5 appeared to act in part by binding to bacterial lipoteichoic acid, thereby suppressing TLR2-to-NF-κB signaling. In addition, in a mouse model of acne vulgaris, P5 exerted both anti-inflammatory and antimicrobial effects against P. acnes, but exerted no cytotoxic effects against skin cells. These results demonstrate that P5, and perhaps other cationic antimicrobial peptides, offer the unique ability to reduce numbers P. acnes cells in the skin and to inhibit the inflammation they trigger. This suggests these peptides could potentially be used to effectively treat acne without adversely affecting the skin.

Dermatology facing autoinflammatory syndrome

Cutaneous symptoms are characteristic for the autoinflammatory disorders (AIDs), both in the classical autoinflammatory phenotype and in most disorders included in this syndrome, but they are not specific and inconstant. Several skin disorders (pyoderma gangrenosum and pustular acne) may be encountered either isolate or associated with autoinflammatory symptoms, forming well-defined clinical entities within the autoinflammatory syndrome. The high prevalence of cutaneous manifestations is an important characteristic of AIDs. The presence of cutaneous symptoms in AIDs opens the perspective of understanding the contribution of innate immunity mechanisms involved in skin pathology. It is possible that many diseases present the alteration, in various degrees, of the innate immune mechanisms. Recently, dermatology faced two challenges connected to AIDs. The first involves the diagnosis of skin symptoms in a clinical autoinflammatory setting and the investigative approach to identify a disorder classified as AID. The second is to identify the altered mechanisms of inborn immunity among the pathogenetic mechanisms of known dermatological diseases (e.g., neutrophilic dermatoses). On the other hand, cutaneous symptoms are in certain cases regarded as a criterion to asses the efficacy of specific or non-specific therapies with monoclonal antibodies in disorders included in AIDs. Dermatology mostly benefits from the identification and knowledge of AIDs due to the role of innate immunity in skin pathogeny and also due to the large extent of clinical forms resulting from the association of skin symptoms with other disorders included in this group.

Evaluation of retinoids for induction of the redundant gene ABCD2 as an alternative treatment option in X-linked adrenoleukodystrophy

X-linked adrenoleukodystrophy (X-ALD), the most common peroxisomal disorder, is a clinically heterogeneous disease that can manifest as devastating inflammatory cerebral demyelination (CALD) leading to death of affected males. Currently, the only curative treatment is allogeneic hematopoietic stem cell transplantation (HSCT). However, HSCT is only effective when performed at an early stage because the inflammation may progress for eighteen months after HSCT. Thus, alternative treatment options able to immediately halt the progression are urgently needed. X-ALD is caused by mutations in the ABCD1 gene, encoding the peroxisomal membrane protein ABCD1, resulting in impaired very long-chain fatty acid metabolism. The related ABCD2 protein is able to functionally compensate for ABCD1-deficiency both in vitro and in vivo. Recently, we demonstrated that of the cell types derived from CD34+ stem cells, predominantly monocytes but not lymphocytes are metabolically impaired in X-ALD. As ABCD2 is virtually not expressed in these cells, we hypothesize that a pharmacological up-regulation of ABCD2 should compensate metabolically and halt the inflammation in CALD. Retinoids are anti-inflammatory compounds known to act on ABCD2. Here, we investigated the capacity of selected retinoids for ABCD2 induction in human monocytes/macrophages. In THP-1 cells, 13-cis-retinoic acid reached the highest, fivefold, increase in ABCD2 expression. To test the efficacy of retinoids in vivo, we analyzed ABCD2 mRNA levels in blood cells isolated from acne patients receiving 13-cis-retinoic acid therapy. In treated acne patients, ABCD2 mRNA levels were comparable to pre-treatment levels in monocytes and lymphocytes. Nevertheless, when primary monocytes were in vitro differentiated into macrophages and treated with 13-cis-retinoic acid, we observed a fourfold induction of ABCD2. However, the level of ABCD2 induction obtained by retinoids alone is probably not of therapeutic relevance for X-ALD. In conclusion, our results suggest a change in promoter accessibility during macrophage differentiation allowing induction of ABCD2 by retinoids.

The Role of the Antioxidative Defense System in Papulopustular Acne

Acne vulgaris frequently occurs in the second decade of life. The pathogenesis of the disease is multifactorial. In this study, we aimed to investigate the role of reactive oxygen species in inflammation of acne by determining the activity of antioxidant defense enzymes in leukocytes. Fifty-two patients with papulopustular type acne vulgaris and 36 healthy controls were enrolled. The severity of the disease was examined by the Global Acne Grading System, and the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) enzymes as well as the level of thiobarbituric acid reactive substance (TBARS) were detected in leukocytes. The activities of SOD and GSH-Px were significantly decreased in the acne group. CAT activity and TBARS level were higher in patients than controls. Only a poor correlation was detected between GSH-Px activity and severity of the disease. Antioxidative defense enzymes are impaired in papulopustular acne, and drugs with antioxidative effects might be valuable in treatment.

Inflammation and acne: putting the pieces together

Acne vulgaris is a common skin disease in which abnormal desquamation, excess sebum production, proliferation of Propionibacterium acnes, and production of proinflammatory mediators all contribute to the pathogenesis of the disease. A review of the literature shows that our current understanding of acne pathogenesis continues to evolve. Recent data suggests that inflammatory mediators may play a more important role than previously realized; however, how these mediators work independently as well as together in acne lesion progression is not well understood. Several cell types and mediators involved in the pathology of acne are responsible for producing or exacerbating an inflammatory response. Here, we present an updated theoretical model of acne lesion progression that highlights the role inflammatory mediators may play throughout acne lesion development.

Toll-like receptor 2 and P. acnes: do they trigger initial acne vulgaris lesions?

OBJECTIVE

To elucidate the role of toll-like receptor 2 (TLR2) in the pathogenesis of acne vulgaris through its immunohistochemical localization in inflammatory and noninflammatory lesions of this disease entity.

STUDY DESIGN

Using standard immunohistochemical techniques, we examined 30 acne cases (involved and noninvolved skin) and the normal skin biopsies of 30 sex- and age-matched, healthy subjects representing the control group.

RESULTS

All examined cases showed positive TLR2 expression in epidermis, pilosebaceous units and dermal inflammatory infiltrate. There were statistically significant differences between acne-involved skin and normal skin and between acne-involved and noninvolved skin regarding TLR2 expression intensity in pilosebaceous units (p < 0.001 for both) and dermal inflammatory infiltrate (p < 0.001 for both). Intense TLR2 expression was in favor of inflammatory acne lesions in pilosebaceous units (p = 0.03) and dermal inflammatory infiltrate (p < 0.05). Intense TLR2 expression was also in favor of severe acne lesions in pilosebaceous units (p = 0.0002) and dermal inflammatory infiltrate (p = 0.001).

CONCLUSION

TLR2 is involved in the pathogenesis of inflammatory and noninflammatory acne lesions. This occurs through Propionibacterium acnes-mediated activation with the resultant release of inflammatory cytokines.

Propionibacterium acnes Induces an IL-17 Response in Acne Vulgaris that Is Regulated by Vitamin A and Vitamin D

Acne vulgaris is the most common skin disorder affecting millions of people worldwide and inflammation resulting from the immune response targeting Propionibacterium acnes has a significant role in its pathogenesis. In this study, we have demonstrated that P. acnes is a potent inducer of T helper 17 (Th17) and Th1, but not Th2 responses in human peripheral blood mononuclear cells (PBMCs). P. acnes stimulated expression of key Th17-related genes, including IL-17A, RORα, RORc, IL-17RA, and IL-17RC, and triggered IL-17 secretion from CD4(+), but not from CD8(+) T cells. Supernatants from P. acnes-stimulated PBMCs were sufficient to promote the differentiation of naive CD4(+)CD45RA T cells into Th17 cells. Furthermore, we found that the combination of IL-1β, IL-6, and transforming growth factor-β-neutralizing antibodies completely inhibited P. acnes-induced IL-17 production. Importantly, we showed that IL-17-expressing cells were present in skin biopsies from acne patients but not from normal donors. Finally, vitamin A (all-trans retinoic acid) and vitamin D (1,25-dihydroxyvitamin D3) inhibited P. acnes-induced Th17 differentiation. Together, our data demonstrate that IL-17 is induced by P. acnes and expressed in acne lesions and that both vitamin A and D could be effective tools to modulate Th17-mediated diseases such as acne.

A small peptide with therapeutic potential for inflammatory acne vulgaris

A designed peptide named LZ1 with 15 amino acid residues containing strong antimicrobial activity against bacteria pathogens of acne vulgaris including Propionibacterium acnes, Staphylococcus epidermidis and S. aureus. Especially, it exerted strong anti-P. acnes ability. The minimal inhibitory concentration against three strains of P. acnes was only 0.6 µg/ml, which is 4 times lower than that of clindamycin. In experimental mice skin colonization model, LZ1 significantly reduced the number of P. acnes colonized on the ear, P. acnes-induced ear swelling, and inflammatory cell infiltration. It ameliorated inflammation induced by P. acnes by inhibiting the secretion of inflammatory factors including tumor necrosis factor-α (TNF-α) and interleukin (IL)-1β. LZ1 showed little cytotoxicity on human keratinocyte and hemolytic activity on human blood red cells. Furthermore, LZ1 was very stable in human plasma. Combined with its potential bactericidal and anti-inflammatory properties, simple structure and high stability, LZ1 might be an ideal candidate for the treatment of acne.

[Pathophysiology of acne. What is confirmed?]

Acne is the most common skin disease worldwide. Choosing the appropriate therapeutic regimens for the clinically diversified disease phenotypes require good knowledge of its pathophysiology. New concepts in this field have been developed in the last 15 years. Acne vulgaris is an inflammatory disorder in which androgens, PPAR ligands, regulating neuropeptides and environmental factors are probably involved as triggers. These factors interrupt the natural cycling process in the sebaceous gland follicle and support the transition of microcomedones to comedones and clinically inflammatory lesions. Proinflammatory lipids, chemokines and cytokines overtake the role of mediators for the further development of acne lesions. Bacterial antigens can potentate the inflammatory phenomena.

Bioactive lipid mediators in skin inflammation and immunity

The skin is the primary barrier from the outside environment, protecting the host from injury, infectious pathogens, water loss and solar ultraviolet radiation. In this role, it is supported by a highly organized system comprising elements of innate and adaptive immunity, responsive to inflammatory stimuli. The cutaneous immune system is regulated by mediators such as cytokines and bioactive lipids that can initiate rapid immune responses with controlled inflammation, followed by efficient resolution. However, when immune responses are inadequate or mounted against non-infectious agents, these mediators contribute to skin pathologies involving unresolved or chronic inflammation. Skin is characterized by active lipid metabolism and fatty acids play crucial roles both in terms of structural integrity and functionality, in particular when transformed to bioactive mediators. Eicosanoids, endocannabinoids and sphingolipids are such key bioactive lipids, intimately involved in skin biology, inflammation and immunity. We discuss their origins, role and influence over various cells of the epidermis, dermis and cutaneous immune system and examine their function in examples of inflammatory skin conditions. We focus on psoriasis, atopic and contact dermatitis, acne vulgaris, wound healing and photodermatology that demonstrate dysregulation of bioactive lipid metabolism and examine ways of using this insight to inform novel therapeutics.

Peptides with antimicrobial and anti-inflammatory activities that have therapeutic potential for treatment of acne vulgaris

The pathogenesis of acne vulgaris is multifactorial involving infection of the pilosebaceous unit with Propionibacterium acnes and a cytokine-mediated inflammatory response. Five frog skin-derived antimicrobial peptides ([D4k]ascaphin-8, [G4K]XT-7, [T5k]temporin-DRa, brevinin-2GU, and B2RP-ERa), chosen for their low hemolytic activity against human erythrocytes, were assessed for their effects on the growth of clinical isolates of P. acnes and on the release of pro-inflammatory and anti-inflammatory cytokines from peripheral blood mononuclear (PBM) cells. All peptides inhibited the growth of P. acnes with the highest potency exhibited by [D4k]ascaphin-8 (minimum inhibitory concentration, MIC=3-12.5 μM). Release of TNF-α from concanavalin A (ConA)-stimulated PBM cells was significantly reduced by [D4k]ascaphin-8, [G4K]XT-7, brevinin-2GU, and B2RP-ERa (1 and 20 μg/ml) and by [T5k]temporin-DRa (20 μg/ml). Release of IFN-γ from unstimulated PBM cells was significantly reduced by [D4k]ascaphin-8 and brevinin-2GU (1 and 20 μg/ml). No peptide showed significant effects on Il-17 release. Release of the anti-inflammatory cytokines TGF-β, IL-4, and IL-10 from both unstimulated and ConA-treated PBM cells was significantly increased by [T5k]temporin-DRa and B2RP-ERa (1 and 20μg/ml). The potent activities of [D4k]ascaphin-8 and [T5k]temporin-DRa in inhibiting the growth of P. acnes and the release of pro-inflammatory cytokines, and in stimulating the release of anti-inflammatory cytokines suggest a possible therapeutic role in the treatment of acne vulgaris.

Inflammation in rosacea and acne: Implications for patient care

Rosacea and acne are chronic inflammatory skin conditions that share an inflammatory pathogenesis, but clinically remain quite distinct. Although many have long assumed that these conditions are primarily infectious, emerging evidence suggests that inflammation plays a critical role in the pathogenesis of these disorders. Part of the innate immune system, the antimicrobial and proinflammatory cathelicidins, may be downregulated by both azelaic acid and sub antimicrobial doxycycline. In acne, the creation of papules, pustules and nodules is clearly mediated through immune mechanisms, and the antiinflammatory effects of retinoids play a key role in management. Recent observations help us understand in greater detail the role that inflammation plays in these two diseases, and the mechanisms by which commonly used medications exert their effect by modulating inflammatory processes. This review will present and synthesize recently acquired information as it relates to inflammatory acne and rosacea pathogenesis and clinical management.

Protease-activated receptor-2 mediates the expression of inflammatory cytokines, antimicrobial peptides, and matrix metalloproteinases in keratinocytes in response to Propionibacterium acnes

Propionibacterium acnes (P. acnes) has been known to produce various exogenous proteases, however, their role in acne pathogenesis remains largely unknown. Proteases elicit cellular responses, at least in part, via proteinase-activated receptor-2 (PAR-2), which is known to mediate inflammation and immune response. In this study, we investigated whether proteases from P. acnes could activate PAR-2 on keratinocytes and induce pro-inflammatory cytokines, antimicrobial peptides (AMPs), and matrix metalloproteinases (MMPs) via PAR-2 signaling. We examined PAR-2 expression and protease activity in acne lesions using immunofluorescence staining and in situ zymography. The effect of the culture supernatant of P. acnes on Ca(2+) signaling in immortalized keratinocytes (HaCaT) was measured using a fluorescence method. HaCaT cells were treated with P. acnes strain ATCC 6919 culture supernatant, with or without pretreatment with serine protease inhibitor or selective PAR-2 antagonist and the gene expression of pro-inflammatory cytokines, AMPs, and MMPs was detected using real-time reverse transcription-polymerase chain reaction. We found that the protease activity and PAR-2 expression were increased in acne lesions. The P. acnes culture supernatant induced calcium signaling in keratinocytes via PAR-2 and stimulated the mRNA expression of interleukin (IL)-1α, -8, tumor necrosis factor (TNF)-α, human beta defensin (hBD)-2, LL-37, MMP-1, -2, -3, -9, and -13 in keratinocytes, which was significantly inhibited by serine protease inhibitor as well as selective PAR-2 specific antagonist. These results indicate that PAR-2 plays an important role in the pathogenesis of acne by inducing inflammatory mediators in response to proteases secreted from P. acnes.

Quantitative PCR of Propionibacterium acnes DNA in samples aspirated from sebaceous follicles on the normal skin of subjects with or without acne

To elucidate whether people with hair follicles containing many Propionibacterium acnes cells are prone to acne, we developed a novel method to count the number of P. acnes in hair follicles. We sampled sebaceous material in hair follicles by aspiration at a constant negative pressure from the nose, forehead, and upper arm of 86 patients with acne vulgaris and 209 control subjects with healthy skin, including 84 subjects age-matched to the patients. Genome-equivalents of P. acnes in samples were estimated by real-time quantitative PCR (TaqMan). Numbers of P. acnes genome-equivalents were extremely low in control subjects less than 10 years of age and generally higher at greater ages, with much variation in subjects in the same decade of life. In men, the median count was highest in controls aged 15-19 years; in women, it peaked twice, in controls aged 15-19 years and again in those aged 40 years or older. P. acnes counts on the forehead and nose were higher in the acne patients aged 10-14 years than in the age-matched controls in both sexes. The counts at three sites were similar in acne patients and controls aged 15 to 29 years in both sexes. The results suggest that people with hair follicles containing many P. acnes cells are not particularly prone to acne, except for younger teenagers. Our aspiration method with estimation by real-time PCR can be used to examine the cutaneous microflora of P. acnes.

The role of toll-like receptors in host defenses and their relevance to dermatologic diseases

The family of toll-like receptors (TLRs) plays a central role in the cutaneous immune defense system. To date, different TLRs have been found on several major cell populations of the skin, such as keratinocytes, fibroblasts, antigen-presenting cells, and melanocytes. Activation of TLRs leads, via different intracellular signaling pathways, to the production of pro-inflammatory stimuli, and is considered a danger signal that should transform the skin in to the functional state of defense. However, TLRs have also been implicated in tissue homeostasis and renewal. Within the group of TLRs, two types have been identified: surface-expressed TLRs, which are predominantly active against bacterial cell wall compounds; and intracellular receptors, which preferentially recognize virus-associated pattern molecules. In addition, surface-expressed receptors trigger phagocytotic and maturation signals, while the intracellular TLRs lead to the induction of antiviral genes. Our review aims to outline the importance of TLRs in the pathogenesis of numerous skin diseases and the potential of TLR agonists as a treatment option for various skin diseases.

Expression of toll-like receptor 2 on peripheral blood monocytes of patients with inflammatory and noninflammatory acne vulgaris

The pathogenesis of acne vulgaris is multifactorial and entails the interplay of hormonal, microbial and immunological events. The bacterium Propionibacterium acnes is involved in the induction of comedogenesis and maintenance of the inflammatory phase of acne. Toll-like Receptor 2 (TLR2) expressed on mononuclear inflammatory cells and possibly on keratinocytes and sebocytes is thought to be of vital importance in mediating P. acnes-induced inflammatory response in acne vulgaris. This work aimed to study the degree of expression of TLR2 on peripheral blood monocytes (PBM) from patients with non-inflammatory and inflammatory acne and to investigate the influence of systemic isotretinoin therapy on TLR2 expression. Sixteen patients with predominantly non-inflammatory acne, 16 patients with predominantly inflammatory acne and 16 age and sex matched healthy subjects were involved in this study. Cell surface expression of CD14 and TLR2 were determined by cell surface staining and flowcytometry. TLR2 expression was analyzed for 12 patients with severe and/or scaring inflammatory acne after oral isotretinoin therapy for two months. The mean fluorescence intensity (MFI) of TLR2 on PBM reported a statistically significant difference between patients with non-inflammatory acne, patients with inflammatory acne and control subjects. MFI of TLR was significantly lower for patients with inflammatory acne after systemic isotretinoin therapy. Data obtained suggest that TLR2 expression on PBM is an important event in acne pathogenesis and targeting this molecule might be a useful therapeutic goal in the future.

[Comparative estimation of medicinal and complex therapy influence on immunological indexes in the patients with acne disease]

The aim of this work is to study the indexes of immune status and level of endogenous intoxication in patients with acne disease, which have got medicinal and complex treatment with using ozone-oxygen mixture (OOM). After complex course of treatment positive changes have happened in regulatory systems - in indexes of cellular and humoral immunity. The treatment with using OOM enabled earlier normalization of absolute and percentage content of T-lymphocytes, removed immunodeficiency of suppressor and helper population of T-lymphocytes, decreased circulating immune complexes, amount of B-lymphocytes. The latter was accompanied by normalization or increase of the level of the separate classes of immunoglobulines. Using OOM resulted in normalization of nonspecific immunity indexes, its bactericide activity. Under the influence of complex treatment of acne disease, statistically important increase of active neutrophiles amount have been observed in comparison with data before treatment and decrease of spontaneous and stimulated indexes of nitroblue-tetrozolit test.

"SAPHO syndrome and infections"

The syndrome of synovitis, acne, pustulosis, hyperostosis, osteitis (SAPHO) encompasses a broad spectrum of cutaneous manifestations associated with osteitic and hyperostotic lesions, which typically may involve the anterior chest wall (ACW). The aetiopathogenetic mechanisms as well as the nosographic framing of the disease are still not fully defined although an important role has been suggested for Propionibacterium acnes (P. acnes). This germ might be able to stimulate both the innate and the T-cell-mediated immune system. The elicited immunological response could be an attempt to eliminate the germ thus inducing the perpetuation of the inflammation. Whether the osteo-articular changes seen in SAPHO could be attributable directly to the infection or to an inflammatory reaction induced by pathogenic material remains a debated issue. The current concept of SAPHO syndrome as a reactive infectious osteitis in genetic predisposed subjects seems appealing, but it has not been yet demonstrated.

CBT-SL5, a bacteriocin from Enterococcus faecalis, suppresses the expression of interleukin-8 induced by Propionibacterium acnes in cultured human keratinocytes

Propionibacterium acnes is known to play a pivotal role in the pathogenesis of acne vulgaris. CBT-SL5 is one of the antimicrobial peptides from Enterococcus faecalis SL5, and it has shown antimicrobial activity against P. acnes. The aim of this study was to investigate the anti-inflammatory effect of CBT-SL5 on the inflammation induced by P. acnes in cultured human keratinocyes. Cultured human keratinocytes derived from neonatal foreskin were treated with heatkilled P. acnes to induce inflammation, and then various concentrations of CBT-SL5 were added to the P. acnestreated keratinocytes. The mRNA expression and protein secretion of interleukin (IL)-8, an inflammation marker, was analyzed by real-time reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. We also analyzed the nuclear factor-kappa B (NF-kappaB) p65 translocation by performing immunofluorescent staining. P. acnes treatment upregulated the IL-8 mRNA expression in the keratinocytes, and this was brought about through both toll-like receptor (TLR)2 and TLR4. At the concentrations of 10, 50, and 100 ng/ml, CBT-SL5 significantly downregulated the P. acnes-induced IL-8 mRNA expression and protein production (p<0.05). At 6 h and 12 h of the treatment, CBT-SL5 significantly suppressed the P. acnesinduced IL-8 mRNA expression. Secretion of IL-8 protein was significantly reduced at 24 h. The functional inhibitory activity of CBT-SL5 was shown by CBT-SL5 suppressing the P. acnes-induced NF-kappaB translocation from the cytoplasm to the nucleus. These results demonstrated that CBT-SL5 suppressed the P. acnes-induced IL-8 expression in keratinocytes. Therefore, CBT-SL5 may be a novel anti-inflammatory treatment for acne.

Anti-Inflammatory Activity of Sertaconazole Nitrate Is Mediated via Activation of a p38–COX-2–PGE2 Pathway

Sertaconazole nitrate is an antifungal agent that exhibits anti-inflammatory activity; however, the mechanism for this action was unknown. We investigated the cellular mechanisms by which sertaconazole exerts its anti-inflammatory activity in keratinocytes and human peripheral blood mononuclear cells (PBMCs). Paradoxically, sertaconazole was found to activate the proinflammatory p38 mitogen-activated protein kinase. Treatment with sertaconazole also resulted in the induction of cyclooxygenase-2 (COX-2) and the subsequent release of prostaglandin E2 (PGE2). Knocking down p38 in keratinocytes using small interfering RNA resulted in an inhibition of sertaconazole-induced PGE2 release confirming that activation of p38 was required for PGE2 production. Additionally, in stimulated keratinocytes and human PBMCs, sertaconazole was found to suppress the release of cytokines. Treatment with anti-PGE2 antiserum or the COX-2 inhibitor NS398 reversed the inhibitory effects of sertaconazole on the release of proinflammatory cytokines, linking endogenous PGE2 with the anti-inflammatory effects. Finally, in an in vivo mouse model of tetradecanoyl phorbol acetate (TPA)-induced dermatitis, the sertaconazole-mediated inhibition of TPA-induced ear edema was reversed by NS398. Biochemical analysis of tissue biopsies revealed increase in PGE2 levels in sertaconazole-treated mice. Thus, activation of the p38-COX-2-PGE2 pathway by agents such as sertaconazole provides anti-inflammatory therapeutic benefits.

Synovitis-acne-pustulosis-hyperostosis-osteitis syndrome and psoriatic arthritis exhibit a different immunogenetic profile

BACKGROUND AND OBJECTIVES

Patients with psoriatic arthritis (PsA) as well as those with synovitis, acne, pustulosis, hyperostosis, osteitis (SAPHO) syndrome share some common features, and in fact, for many authors the SAPHO concept fits well into the broader concept of PsA. However, some clinical features are unique to the SAPHO syndrome, and in the other hand, these patients do not show the known association between the HLA-B27 antigen and the spondyloarthropathies. To date, there are no studies comparing the immunogenetic profile of these two conditions, so the main objective of the present report was to analyse whether or not both entities may share the same genetic basis.

PATIENTS AND METHODS

All patients with SAPHO syndrome (n=25) seen in a single university hospital from 1985 to 2005 were recruited and followed up in standardised manner in order to study their main characteristics and HLA profile. The HLA-Cw6, DR and B27 antigen distribution of these cases was compared to that of 50 patients with psoriasis vulgaris, 120 with PsA, and 170 healthy blood donors. PsA patients were classified in accordance with their predominant pattern observed in the last 5 years of disease evolution. Odds ratios (OR) values were calculated to measure the strength of the association between HLA antigens and disease, while the statistical significance of the association was assessed with a two-tailed Fisher's exact test. P<0.05 values were considered significant.

RESULTS

No association was found between HLA-Cw6, B27, or DR antigens, and SAPHO syndrome. HLA-Cw6 was strongly associated with psoriasis, OR 12 (95% CI: 5.6-26, p<0.0001) and PsA, OR 10 (95% CI: 5.4-19.5, p<0.0001), however this antigen was equally distributed among the three articular categories of PsA. HLA-DR4 was found under-represented in PsA patients compared to controls, OR 0.4 (95% CI: 0.2-0.7, p=0.002). HLA-DR7 correlated well with psoriatic oligoarthritis, OR 9.6 (95% CI: 2.9-28, p<0.0001), HLA-DR8 was found associated with polyarthritis, OR 6.7 (95% CI: 2-25, p=0.002), while HLA-B27 was over-represented in psoriatic spondylitis, OR 10 (95% CI: 3.3-25, p<0.0001).

CONCLUSIONS

Psoriasis/PsA and SAP-HO syndrome show a different immunogenetic background, however the genetic basis of SAPHO syndrome remains unknown.

Is minocycline therapy in acne associated with antineutrophil cytoplasmic antibody positivity? A cross-sectional study

BACKGROUND

Minocycline (MN), one of the commonly prescribed therapies for acne, is known to be associated with autoimmune disorders including drug-induced lupus. However, data are sparse regarding the prevalence of autoimmune disease in acne or in patients with acne treated with MN.

OBJECTIVES

To establish the prevalence of antinuclear antibodies (ANA), antineutrophil cytoplasmic antibodies (ANCA) and new autoimmune syndromes in an MN-exposed and unexposed population with acne.

METHODS

In a cross-sectional study, 252 patients with acne vulgaris were assessed. Sixty-nine per cent had been exposed to MN at some point or were taking the drug at the time of the interview. Data recorded included duration of disease (acne) and drug history as well as possible side-effects of drugs, in particular joint symptoms (pain and swelling). In addition, blood was taken for ANA, ANCA, liver function tests and HLA analysis.

RESULTS

There was no statistical difference in the prevalence of ANA positivity between patients exposed (13%) or not exposed (11%) to MN. However, higher titres of ANA (1/160 or higher) were found in the MN-exposed group (45% compared with 12% in the unexposed group). ANCA positivity was found in 7% of the MN-exposed group but no positivity was found in the unexposed cohort (P = 0.022). In 58% of cases, the ANCA detected were of the perinuclear pattern (p-ANCA) with myeloperoxidase specificity, and this finding was associated with clinical symptoms in the majority of cases. Two p-ANCA-positive patients were thought in retrospect to have developed a drug-induced lupus syndrome.

CONCLUSIONS

ANA positivity is seen in patients with acne irrespective of exposure to MN; however, p-ANCA appear to be a serological marker for developing autoimmune disease in patients receiving MN.

[Sebaceous glands and acne]

New studys on the sebaceous glands in recent years have facilitated the further understanding and treatment of acne vulgaris. This article summarizes the advancements in the relationship between sebaceous glands and acne, with focus on androgen metabolism in skin, abnormal lipids secretion, and immunology of sebaceous gland cells.

Variable expression of immunoreactive surface proteins of Propionibacterium acnes

Despite accumulating data implicating Propionibacterium acnes in a variety of diseases, its precise role in infection remains to be determined. P. acnes antigen-specific CD4(+) T cells are present in early inflamed acne lesions and may be involved in the inflammatory response; however, little is known about the specific antigens involved. In this study, B cell and T cell antigens from P. acnes expression libraries were cloned and evaluated and the four predominant proteins identified were investigated. Two of these antigens share some homology with an M-like protein of Streptococcus equi and have dermatan-sulphate-binding activity (PA-25957 and 5541). The remaining two antigens, PA-21693 and 4687, are similar to the product of the Corynebacterium diphtheriae htaA gene from the hmu ABC transport locus, although only one of these (PA-21693) is encoded within an hmu-like operon and conserved amongst a range of clinical isolates. All four proteins contain an LPXTG motif, although only PA-21693 contains a characteristic sortase-sorting signal. Variation in the expression of PA-4687, 25957 and 5541 is evident amongst clinical isolates and is generated both by frameshifts associated with the putative signal peptide and by variable numbers of repeat regions toward the carboxy-terminus, potentially generating heterogeneity of molecular mass and antigenic variation. In addition, in the case of PA-25957, a frameshift in a C-rich region at the extreme carboxy-terminus eliminates the LPXTG motif in some isolates. For the dermatan-sulphate-binding PA-25957, IgG1 antibody in serum from acne-positive donors was shown to be specific for the amino-terminal region of the protein, which also contains a CD4(+) T cell epitope. In contrast, serum from acne-negative donors shows an IgG2 and IgG3 antibody subclass response to the carboxy-terminal region. These data have implications for the potential role of P. acnes in inflammatory acne and other diseases.

Resolution of inflammatory acne vulgaris may involve regulation of CD4+ T-cell responses to Propionibacterium acnes

BACKGROUND

Propionibacterium acnes has been strongly implicated in inflammatory acne. However, its role in the disease is unclear. It has been hypothesized that an immune response to P. acnes and/or P. acnes heat shock proteins (HSPs) may play a role in the pathogenesis of inflammatory acne.

OBJECTIVES

To compare the cell-mediated immune response to P. acnes and HSPs in acne patients, nonacne controls and individuals with resolved acne.

METHODS

The proliferative response of peripheral blood mononuclear cells (PBMC) from acne patients, resolved acne donors and healthy controls to P. acnes, P. acnes HSP60 and HSP70, and mycobacterial HSPs was assessed by lymphocyte transformation assay (LTA). The proliferative response of purified CD4+ T cells was further analysed by limiting dilution analysis (LDA). Contingency tables (G-test) were used to analyse the proportion of individuals in each group showing a positive proliferative response for LTA or data fitting single-hit kinetics for LDA.

RESULTS

Analysis of stimulation of PBMC with P. acnes, P. acnes HSP60 and HSP70 in the LTA showed the proportion of positive responders to be independent of subject group. However, the proportion of acne patients with a positive response to mycobacterial HSPs was significantly higher than those for the other subject groups. Analysis of LDA data showed the proportion of resolved donors with responses to P. acnes fitting the single-hit kinetics model to be significantly lower than those of the other groups. There were no significant differences in responses to other antigens.

CONCLUSIONS

The significantly lower proportion of resolved donors demonstrating a single-hit kinetics response to P. acnes by LDA may represent negative regulation of the CD4+ T-cell response to P. acnes in these subjects.

Anti-inflammatory activity of cationic peptides: application to the treatment of acne vulgaris

Cationic antimicrobial peptides exhibit potent antimicrobial activity against clinically relevant microorganisms including Propionibacterium acnes. Recent studies showed that, in addition to the antimicrobial activity, these peptides can exhibit an anti-inflammatory effect. These properties make cationic peptides attractive drug candidates for the treatment of acne vulgaris, a disease with both bacterial and inflammatory components. This review focuses on the anti-inflammatory activity of cationic antimicrobial peptides and its application for the treatment of acne vulgaris. The anti-inflammatory activity of cationic peptides in acne vulgaris can be explained by their ability to both bind proinflammatory bacterial factors (e.g. lipoteichoic acid), sequestering them from the site of inflammation, and to inhibit the secretion of proinflammatory cytokines (e.g. tumor necrosis factor-alpha, IL-1) by host cells. These anti-inflammatory effects combined with potent antimicrobial activity may translate into a novel therapeutic option for acne vulgaris.

Hereditary auto-inflammatory disorders and biologics

The term auto-inflammatory disorders has been coined to describe a group of conditions characterized by spontaneously relapsing and remitting bouts of systemic inflammation without apparent involvement of antigen-specific T cells or significant production of auto-antibodies. The hereditary periodic fever syndromes are considered as the prototypic auto-inflammatory diseases, and genetic studies have yielded important new insights into innate immunity. DNA analysis has greatly enhanced the clinical characterization of these conditions, and elucidation of their molecular aetiopathogenesis has suggested that therapies may be aimed at specific targets within the immune cascade. The availability of biologic response modifiers such as inhibitors of tumour necrosis factor (TNF) and interleukin-1beta has greatly improved the outlook for some of these disorders, although effective therapies remain elusive in patients with certain conditions, including hyperimmunoglobulinaemia-D with periodic fever syndrome (HIDS) and a proportion of those with TNF-receptor associated periodic syndrome (TRAPS). Indeed, outstanding challenges and the unique potential to further elucidate molecular mechanisms in innate immunity are illustrated by the dashed early hope that TNF blockade would be a panacea for TRAPS: not only is etanercept (Enbrel) ineffective in some cases, but there are anecdotal reports of this condition being greatly exacerbated by infliximab (Remicade).

Review of the innate immune response in acne vulgaris: activation of Toll-like receptor 2 in acne triggers inflammatory cytokine responses

Acne vulgaris is a common disorder that affects 40-50 million people in the USA alone. The pathogenesis of acne is multifactorial, including hormonal, microbiological and immunological mechanisms. One of the factors that contributes to the pathogenesis of acne is Propionibacterium acnes; yet, the molecular mechanism by which P. acnes induces inflammation is not known. Recent studies have demonstrated that microbial agents trigger cytokine responses via Toll-like receptors (TLRs). TLRs are pattern recognition receptors that recognize pathogen-associated molecular patterns conserved among microorganisms and elicit immune responses. We investigated whether TLR2 mediates P. acnes-induced cytokine production in acne. Using transfectant cells we found that TLR2 was sufficient for NF-kappaB activation in response to P. acnes. In addition, peritoneal macrophages from wild-type, TLR6 knockout and TLR1 knockout mice, but not TLR2 knockout mice, produced IL-6 in response to P. acnes.P. acnes induced activation of IL-12 and IL-8 production by primary human monocytes, and this cytokine production was inhibited by anti-TLR2-blocking antibody. Finally, in acne lesions, TLR2 was expressed on the cell surface of macrophages surrounding pilosebaceous follicles. These data suggest that P. acnes triggers inflammatory cytokine responses in acne by activation of TLR2. As such, TLR2 may provide a novel target for the treatment of this common skin disease.