Lymphocyte transformation in subjects with nodulo-cystic acne

Patients with severe nodulo-cystic acne are known to have elevated serum antibody levels and increased immediate hypersensitivity reactions to Propionibacterium acnes. This organism is the predominant bacterium in normal pilosebaceous follicles of human skin, and can be consistently isolated from pustular lesions in acne. Previously it had been observed that delayed cutaneous hypersensitivity reactions to P. acnes were negative in patients with acne. The present study investigated the proliferative response of lymphocytes from patients with nodulo-cystic acne to phytohaemagglutinin (PHA) and P. acnes antigen stimulation. The response to PHA stimulation was within normal limits. The response to P. acnes antigen showed a significant increase over control values obtained by testing lymphocytes from acne-free subjects. Thus cell mediated immunity to P. acnes may be present in subjects with severe inflammatory acne. These findings raise the possibility that reactions to P. acnes may contribute to intensifying the inflammatory response in acne lesions.     

Evidence for diversity within Propionibacterium acnes: a comparison of the T-cell stimulatory activity of isolates from inflammatory acne, endocarditis and the laboratory

BACKGROUND: Propionibacterium acnes is primarily associated with the pathogenesis of acne vulgaris but reports are increasing in number implicating P. acnes in other diseases such as abscess formation, meningitis and endocarditis. The pathogenicity of P. acnes is thought to be partly due to the interaction of the bacterium with the immune system. Historically, investigations have focused on humoral and cell-mediated immune responses to P. acnes antigens without attention to the possibility that different antigens may be expressed by different isolates. OBJECTIVE: Investigations were performed to determine whether there were differences between a laboratory strain of P. acnes (P-37) and fresh clinical isolates in their ability to stimulate naive and adult lymphocytes. MATERIAL AND METHODS: The fresh isolates were collected from a patient with inflammatory acne and a patient with P. acnes-induced prosthetic valve endocarditis. The lymphocyte transformation assay was used to detect responses to whole-cell suspensions of stationary phase P. acnes isolates during 7 days of incubation. RESULTS: The acne isolate was significantly more stimulatory for cord blood mononuclear cells (CBMNCs) than the laboratory isolate (P. acnes P-37) at day 4 of incubation. There were no significant differences between the three strains at any other time points. However, the isolate cultivated from inflammatory acne was significantly more stimulatory for peripheral blood mononuclear cells (PBMNCs) from acne donors than the endocarditis isolate or the laboratory strain at most time points. There were no significant differences between the endocarditis strain and the laboratory strain. CONCLUSION: It can be hypothesized that in case of P. acnes-induced endocarditis lymphocyte stimulation is a disadvantage for the microorganism and therefore a lack of lymphocyte stimulation may be relevant to the pathogenesis of endocarditis.     

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.     

The integral role of topical and oral retinoids in the early treatment of acne

This article will review the rationale for early use of topical retinoids alone or in combination with topical antimicrobials in light of the pathogenesis of microcomedones and later lesions. Knowledge of the pathogenic processes in acne vulgaris has risen dramatically over the last three decades. It is now widely accepted that acne is the result of four distinct processes: increased proliferation, cornification, and shedding of follicular epithelium; increased sebum production; colonization of the follicle with Propionibacterium acnes ; and induction of inflammatory responses by bacterial antigens and cell signals. Clinical focus of disease management has shifted toward earlier treatment targeting these fundamental processes. Elimination of microcomedones, the precursor to all subsequent lesions, would optimize acne therapy by preventing the later inflammatory stages of disease. With the exception of oral isotretinoin, no single first-line agent addresses all pathogenic mechanisms. Topical retinoids have comedolytic and in some cases anti-inflammatory effects, but have no direct impact on P. acnes . Thus treatment with a combination of topical retinoid and topical antimicrobial is warranted. The former can also enhance penetration of the latter by increasing microcomedonal extrusion. In selecting a combination, one must consider efficacy, cost, and likelihood of compliance. Once thought to be effective primarily for treating comedones, topical retinoids have also been demonstrated to be effective in reducing inflammatory lesions. The activity of a topical retinoid combined with an antimicrobial agent has been shown to clear more lesions and to clear them more rapidly than antimicrobial therapy alone. Topical retinoids are also used effectively to maintain remissions.     

Antibiotic susceptibility of Propionibacterium acnes isolated from acne vulgaris in Korea

Propionibacterium acnes plays an important role in the development of acne, and inflammatory lesions are improved by antibiotics. Long-term use of antibiotics may result in development of resistant strains and treatment failure. The aim of the present study was to investigate the isolation rate of P. acnes and to evaluate its antibiotic susceptibility to widely used antibiotics in acne in Korea. Among 46 patients, 31 P. acnes strains were cultured. Isolated P. acnes was measured for minimum inhibitory concentration (MIC) of tetracycline, doxycycline, minocycline, erythromycin and clindamycin using an Epsilometer test. Age, disease duration and previous history of antibiotic therapy for acne were compared in relation to the MIC. The mean MIC of tetracycline, minocyclines, doxycycline, clindamycin and erythromycin were all below the breakpoint of antibiotic resistance. The patients with acne vulgaris with disease duration of more than 2 years documented higher MIC values in doxycycline, erythromycin, and clindamycin than those of less than 2 years. The patients who were previously treated with topical or systemic antibiotics showed higher MIC in doxycycline. Antibiotic resistance of P. acnes is still low in Korea, but at this point, there is an increasing trend of MIC. Caution and acknowledgement of increased risk of antibiotic resistant P. acnes should be advised in acne antibiotic treatment to minimize and avoid the emergence of the resistant strain.     

The evolving role of Propionibacterium acnes in acne

Propionibacterium acnes is a member of the resident cutaneous flora. Sebaceous follicles involved in acne are characterized by the accumulation of abnormally desquamated corneocytes and excess sebum-the microcomedo. This environment provides ideal growth conditions for P acnes. Several orders of magnitude level of P acnes are found in microcomedos. P acnes produces a variety of chemotactic factors and proinflammatory molecules that are responsible for the inflammatory phase of acne. Antibiotic therapy works by reducing the viable number of P acnes as well as by reducing the production of inflammatory stimuli. Antibiotic therapy has been a mainstay of treatment for more than 30 years. In the last decade, decreased sensitivity to antibiotics has developed and clinical resistance has been described. This development threatens the usefulness of antibiotic therapy in the future.     

Nadifloxacin, an antiacne quinolone antimicrobial, inhibits the production of proinflammatory cytokines by human peripheral blood mononuclear cells and normal human keratinocytes

BACKGROUND: Acne vulgaris is a chronic inflammatory disease involving colonization of Propionibacterium acnes (P. acnes), activation of neutrophils and lymphocytes. Circumstantial evidence suggests that antigen-independent and -dependent immune responses against P. acnes are involved in the pathogenesis of inflammatory acne. Epidermal keratinocytes are also suggested to be involved in initiation and progression of cutaneous inflammation. Nadifloxacin, a fluorinated quinolone, has potent antimicrobial activities against Gram-negative and -positive microbes and is used to treat multiple inflamed acne lesions. However, its effect on immune conferring cells such as mononuclear cells and keratinocytes has not been examined. OBJECTIVE: To evaluate the possible involvement of potential anti-inflammatory activity of nadifloxacin in its therapeutic effect on inflammatory acne, we examined the effects of nadifloxacin, in comparison with other antibiotics used to treat acne vulgaris, on cytokine production by human peripheral blood mononuclear cells (PBMC) and keratinocytes. METHODS: Cytokine production by PBMC was determined after treatment with heat-killed P. acnes in the presence or absence of antimicrobials using a real-time PCR and ELISA. Cultured human epidermal keratinocytes were stimulated by IFN-gamma plus IL-1beta and the effects of antimicrobials were examined by using ELISA. RESULTS: Nadifloxacin as well as macrolide antibiotics and clindamycin inhibited IL-12 and IFN-gamma production by PBMC stimulated by heat-killed P. acnes. The drug also inhibited the IL-1alpha, Il-6, IL-8 and GM-CMS production by keratinocytes treated with IFN-gamma plus IL-1beta. CONCLUSIONS: Inhibitory effects of nadifloxacin to activate T cells and keratinocytes may be involved at least in part in the mechanism of its therapeutic effect against inflammatory acne.     

All-trans retinoic acid shifts Propionibacterium acnes-induced matrix degradation expression profile toward matrix preservation in human monocytes

Propionibacterium acnes is a critical component in the pathogenesis of acne vulgaris, stimulating the production of various inflammatory mediators, such as cytokines and chemokines, important in the local inflammatory response found in acne. This study explored the role of P. acnes and its ability to induce matrix metalloproteinases (MMPs) in primary human monocytes and how this induction is regulated by retinoids. MMP-1- and MMP-9-expressing cells were present in perifollicular and dermal inflammatory infiltrates within acne lesions, suggesting their role in acne pathogenesis. In vitro, we found that P. acnes induced MMP-9 and MMP-1 mRNA, and the expression of MMP-9, but not of MMP-1, was found to be Toll-like receptor 2-dependent. P. acnes induced the mRNA expression of tissue inhibitors of metalloproteinase (TIMP)-1, the main regulator of MMP-9 and MMP-1. Treatment of monocytes with all-trans retinoic acid (ATRA) significantly decreased baseline MMP-9 expression. Furthermore, co-treatment of monocytes with ATRA and P. acnes inhibited MMP-9 and MMP-1 induction, while augmenting TIMP-1 expression. These data indicate that P. acnes-induced MMPs and TIMPs may be involved in acne pathogenesis and that retinoic acid modulates MMP and TIMP expression, shifting from a matrix-degradative phenotype to a matrix-preserving phenotype.     

Acne and Propionibacterium acnes

The involvement of microorganisms in the development of acne has a long and checkered history. Just over 100 years ago, Propionibacterium acnes (then known as Bacillus acnes) was isolated from acne lesions, and it was suggested that P. acnes was involved in the pathology of the disease. The 1960s saw the use of antibiotics to treat acne, and the consequent clinical success combined with reductions in P. acnes gave new impetus to the debate. Over the past two decades, the inevitable emergence of antibiotic-resistant strains of P. acnes as a consequence of acne therapy not only has reopened the debate as to the role of P. acnes in acne, but also has created some serious health care implications.     

On the propionibacteria in the pilosebaceous ducts of uninvolved skin of acne patients

Summary In 24 persons with a severe inflammatory acne and 48 control subjects, bacteria were sampled from the sebaceous gland excretory ducts with the glass sampling head method according to Holland et al. After anaerobic culture bacterial counts were performed. The total numbers of P. acnes and the frequency of detection of P. granulosum were determined. The bacterial counts of P. acnes were almost idendical in the two collectives. P. granulosum was detected at a significantly higher frequence in the acne patients than in the control subjects. It can be assumed on the basis of the results that an increase in the bacterial counts of P. acnes is not to be regarded as a pathogenetic factor in the inflammatory acne of older patients. On the other hand, they suggest that P. granulosum may have an appreciable role in acne.     

Newer approaches in topical combination therapy for acne

Acne vulgaris is a common chronic inflammatory cutaneous disease involving the pilosebaceous unit. Its pathophysiology is multifactorial and complex, including obstruction of the pilosebaceous unit due to increased sebum production, abnormal keratinization, proliferation of Propionibacterium acnes (P. acnes), and inflammation. Topical agents are the most commonly used therapy for acne. First generation topicals mainly consist of single agent retinoids, benzoyl peroxide (BPO) and antibacterials that target comedones, P. acnes, and inflammation. Novel topical therapies include combination products with advanced vehicle formulations that target multiple acne pathophysiologies and offer simplified treatment regimes. For example, the combination of clindamycin and tretinoin in a unique vehicle formulation allows for progressive follicle penetration and decreased irritation, resulting in increased efficacy. Furthermore, adapalene or clindamycin with BPO combinations target comedones, inflammation, and P. acnes synergistically. These newer combination products have the potential to increase both efficacy and patient adherence when compared with single agent treatment.     

Acne vulgaris and malignancy

Seventy patients with lymphomas and leukaemias were interviewed. Details of past acne vulgaris were recorded and a clinical examination performed. A history of acne was less common in the patients than in matched controls. In addition, fewer patients had received treatment prescribed by a medical practitioner for their acne than had the controls. Examination revealed fewer patients with acne. These results suggest a reduced incidence of acne or its more severe forms in patients who have developed lymphomas and leukemias, and provide some support for the hypothesis that increased exposure or response to P. acnes, as appears to occur with acne, could confer protection against malignant disease.     

Delayed skin test reactivity to Propionibacterium acnes correlates with severity of inflammation in acne vulgaris

Propiontibacterium acnes is the bacterial species most consistently isolated from acne lesions. Intradermal injection of a heat-killed suspension of P. acnes induced a delayed erythematous and often papular inflammatory reaction which was maximal after 24–48 h. This response was dose related and was probably mediated at least partly by immune mechanisms. In eighty-one subjects with acne of varying severity the intensity of the 48 h skin test reaction was significantly related to the severity of the acne. These findings indicate that the host response to P. acnes is an important variable in determining the severity of inflammatory acne.     

Systemic Isotretinoin Therapy Normalizes Exaggerated TLR-2-Mediated Innate Immune Responses in Acne Patients

Retinoids are used in the treatment of inflammatory skin diseases and malignancies, but studies characterizing the in vivo actions of these drugs in humans are lacking. Isotretinoin is a pro-drug for all-trans retinoic acid, which can induce long-term remissions of acne; however, its complete mechanism of action is unknown. We hypothesized that isotretinoin induces remission of acne by normalizing the innate immune response to the commensal bacterium Propionibacterium acnes. Compared with normal subjects, peripheral blood monocytes from acne patients expressed significantly higher levels of Toll-like receptor 2 (TLR-2) and exhibited significantly greater induction of TLR-2 expression following P. acnes stimulation. Treatment of patients with isotretinoin significantly decreased monocyte TLR-2 expression and subsequent inflammatory cytokine response to P. acnes after 1 week of therapy. This effect was sustained 6 months following cessation of therapy, indicating that TLR-2 modulation may be involved in the durable therapeutic response to isotretinoin. This study demonstrates that isotretinoin exerts immunomodulatory effects in patients and sheds light on a potential mechanism for its long-term effects on acne. The modulation of TLR-2 expression on monocytes has important implications in other inflammatory disorders characterized by TLR-2 dysregulation.     

Induction of toll-like receptors by Propionibacterium acnes

BACKGROUND: The bacterium Propionibacterium acnes is involved in the induction and maintenance of the inflammatory phase of acne. Recent studies have found that keratinocytes express toll-like receptors (TLRs) implicated in immediate immunity. No studies have, to date, been carried out on the action of P. acnes upon TLR activation in keratinocytes. OBJECTIVES: Focusing on the inflammatory phase of acne, to clarify the role of P. acnes in immediate immunity by inducing expression of TLR-2 and TLR-4 by keratinocytes. We also studied how the secretion and expression of matrix metalloproteinase (MMP)-9 is induced by P. acnes. METHODS: The work was carried out on two levels: in vivo with the study of the expression of TLR-2 and TLR-4 proteins in biopsies of acne lesions and in vitro on cultured keratinocyte monolayers to study the modulating effects of P. acnes on the expression of TLR-2 and TLR-4 and also on the expression and secretion of MMP-9. RESULTS: Our findings reveal that in vivo TLR-2 and TLR-4 expression is increased in the epidermis of acne lesions. In vitro, an increase in TLR-2 and TLR-4 expression by human keratinocytes occurred in the first hours of incubation with bacterial fractions as well as an increase of the expression and secretion by the keratinocytes of MMP-9, which plays a role in inflammation. CONCLUSIONS: This work demonstrates that P. acnes induces TLR expression and that this mechanism could play an essential role in acne-linked inflammation. These receptors could be involved notably in acute acne.     

Antibodies to P. acnes and P. acnes exocellular enzymes in the normal population at various ages and in patients with acne vulgaris

Total serum IgM and IgG agglutinins to P. acnes and neutralizing antibodies to P. acnes lipase, hyaluronate lyase and acid phosphatase were measured in normal individuals of different age groups. Agglutinins to P. acnes were detected in infants at 4 months of age and were present at a high level throughout life. A switch from predominantly IgM agglutinins in children, to IgG agglutinins in adults, occurred during adolescence. Anti-P. acnes lipase antibodies were present in 20% of teenagers and 17-42% of adults. Anti-P. acnes hyaluronate lyase antibodies were found in adults only (4-17%). Antibodies to acid phosphatase were not detected. Agglutinins to P. acnes were measured in individuals with mild, moderate and severe acne, and in normal controls. Only patients with severe acne had significantly higher titres than the controls. IgM and IgG agglutinins were determined in 13-14-year-olds with mild, moderate and severe acne, and in normal controls. Thirty-three per cent, 60% and 100% of the acne patients, respectively, but none of the normal controls, had predominantly IgG agglutinins. No difference in the prevalence or titre of antibodies to P. acnes exocellular enzymes was observed when patients with severe acne were compared with normal controls. There was no evidence to suggest a role for antibodies to P. acnes exocellular enzymes in the initiation of inflammatory acne.     

Distinct strains of Propionibacterium acnes induce selective human beta-defensin-2 and interleukin-8 expression in human keratinocytes through toll-like receptors

Acne is a chronic inflammatory disease of the pilosebaceous follicle. One of the main pathogenetic factors in acne is the increased proliferation of Propionibacterium acnes (P. acnes) in the pilosebaceous unit. We investigated whether direct interaction of P. acnes with keratinocytes might be involved in the inflammation and ductal hypercornification in acne. The capacities of different P. acnes strains to activate the innate immune response and the growth of cultured keratinocytes were investigated. We have found that two clinical isolates of P. acnes significantly induced human beta-defensin-2 (hBD2) messenger RNA (mRNA) expression; in contrast a third clinical isolate and the reference strain (ATCC11828) had no effect on hBD2 mRNA expression. In contrast, all four strains significantly induced the interleukin-8 (IL-8) mRNA expression. The P. acnes-induced increase in hBD2 and IL-8 gene expression could be inhibited by anti-Toll-like receptor 2 (TLR2) and anti-TLR4 neutralizing antibodies, suggesting that P. acnes-induced secretion of soluble factors in keratinocytes are both TLR2 and TLR4 dependent. In addition, the clinical isolate P. acnes (889) was capable of inducing keratinocyte cell growth in vitro. Our findings suggest that P. acnes modulates the antimicrobial peptide and chemokine expression of keratinocytes and thereby contributes to the recruitment of inflammatory cells to the sites of infections.     

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.     

痤疮的抗生素治疗及耐药现状

痤疮丙酸杆菌在痤疮发生、发展过程中起着重要作用,外用或口服抗生素对痤疮炎性皮损有肯定疗效。然而随着抗生素的广泛使用,耐药问题日益严峻,研究表明超过50%的痤疮丙酸杆菌出现了耐药,尤其是对大环内酯类抗生素。本文对抗生素治疗痤疮的作用机理与使用现状、耐药机制与耐药现状进行综述。     

Zinc salts inhibit in vitro Toll-like receptor 2 surface expression by keratinocytes

Propionibacterium acnes (P. acnes) plays an important role in the induction and maintenance of the inflammatory phase of acne. At the therapeutic level, it has been shown that zinc salts could have a beneficial effect on mild and moderate inflammatory acne lesions. However, their mechanisms of action are still only partially known. Immediate early immune response is a crucial route in the development of inflammatory reaction and, specifically, activation of Toll-like Receptors (TLRs) leading to nuclear factor (NF)-kappaB translocation and production of inflammatory cytokines such as interleukin-8 (IL-8). The aim of this work was to determine if cytokine secretion and innate immunity could be targets of zinc salts. Normal Human Epidermal Keratinocytes (NHEK) and skin explants were stimulated by P. acnes extracts and incubated (3 h) with zinc salts (1 microg/mL). Then we successively studied TLR2 expression by immunohistochemistry and IL-8 production by ELISA. After incubation with zinc salts, the increase of TLR2 surface expression in skin upon membrane fraction (FM) of P. acnes challenge was decreased as compared to that in control samples. However, this inhibition does not modify IL-8 secretion by keratinocytes. In conclusion the inhibition of TLR2 surface expression by keratinocytes could be one of the anti-inflammatory mechanisms of zinc salts in acne.