Acne from an immunological perspective.

Patients with acne vulgaris, particularly those with severe inflammatory forms of the disease, are known to have high titers of serum antibodies, and intensified immediate hypersensitivity reactions to P. acnes antigens. The significance of this fact has not been clarified, but it is possible that antigen-antibody reactions involving P. acnes in the perifollicular dermis could intensify the inflammatory response in certain forms of acne. Further studies utilizing newer, more sophisticated techniques are needed to identify the role of P. acnes antigens in affecting such fundamental phenomena as chemotaxis, cell-mediated immunity, activation of the complement cascade and reticuloendothelial system stimulation. Answers to these basic questions have the pathogenesis of that common but even more complex disease, 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.     

Evaluation of delayed type immune reactivity in patients with acne vulgaris

The delayed-type immune reactivities of 39 patients suffering from moderate to severe papulopustular or nodulo-cystic forms of Acne vulgaris were compared with healthy acne-free controls. In vivo reactivity was assessed by skin testing with four common recall antigens. In vitro the afferent arm of the immune system was assayed by antigen and mitogen simulated lymphocyte transformation and the efferent arm by granulocyte random migration and by granulocyte responsiveness to a standard migration inhibitory lymphokine preparation. Spontaneous lymphocyte transformations were also evaluated. In acne patients the skin test reactivities were in general only slightly decreased. Their lymphocytes showed relatively normal responses to mitogen stimulation, but antigen responsiveness was significantly diminished. Furthermore the patients' lymphocytes showed increased spontaneous transformation. All these changes correlated, to some extent, with the severity of the disease. The granulocytes of acne patients showed increased random migration, of borderline significance, but the granulocyte responses to the lymphokine preparation were completely normal. The results suggest that immunologic abnormalities are mild and probably secondary to the inflammatory process.     

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.     

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.     

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.     

Propionibacterium acnes and inflammation in acne; P. acnes has T-cell mitogenic activity

BACKGROUND: Circumstantial evidence suggests that Propionibacterium acnes has a role in the inflammation of acne. This could be effected by antigenic or superantigenic or mitogenic reactions. OBJECTIVES: The purpose of this investigation was to determine whether P. acnes had only antigenic activity or additional superantigenic and mitogenic activity. METHODS: A lymphocyte transformation assay was used to detect responses to a mixture of eight P. acnes whole cell isolates, and their supernatant culture fluids. In order to determine the nature of T-cell reactions to P. acnes cells a mouse-antihuman major histocompatibility complex class II monoclonal antibody was used in the lymphocyte transformation assay to inhibit the antigenic stimulation of lymphocytes. An analysis of the T-cell receptor (TCR) variable region beta (BV) repertoire was undertaken using flow cytometry of the unstimulated and stimulated cells. RESULTS: Peripheral blood mononuclear cells (PBMNC) from adults with no history of acne responded strongly to stationary growth phase cells of P. acnes, less strongly to cells in the exponential growth phase. No response was detected to supernatant culture fluids. PBMNC from five cord blood samples (CBMNC) responded maximally after 3 and 7 days of incubation with stationary growth phase cells of P. acnes. The reaction of CBMNC to P. acnes cells was not suppressed completely by the blocking antibody. The analysis of the TCRBV repertoire indicated that P. acnes induced no deletion or over-representation of certain BV element-bearing T cells. The TCRBV analysis was repeated after preincubation with the blocking antibody. Deletion of T cells bearing certain BV components occurred and there was no over-representation of T cells carrying certain BV components. CONCLUSIONS: Two mechanisms of lymphocyte activation by P. acnes cells are proposed, antigen and mitogen driven. These results are consistent with the histological evidence of inflammation in acne lesions.     

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.     

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.     

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.     

Gene array expression profiling in acne lesions reveals marked upregulation of genes involved in inflammation and matrix remodeling

The pathogenesis of acne has been linked to multiple factors such as increased sebum production, inflammation, follicular hyperkeratinization, and the action of Propionibacterium acnes within the follicle. In an attempt to understand the specific genes involved in inflammatory acne, we performed gene expression profiling in acne patients. Skin biopsies were obtained from an inflammatory papule and from normal skin in six patients with acne. Biopsies were also taken from normal skin of six subjects without acne. Gene array expression profiling was conducted using Affymetrix HG-U133A 2.0 arrays comparing lesional to nonlesional skin in acne patients and comparing nonlesional skin from acne patients to skin from normal subjects. Within the acne patients, 211 genes are upregulated in lesional skin compared to nonlesional skin. A significant proportion of these genes are involved in pathways that regulate inflammation and extracellular matrix remodeling, and they include matrix metalloproteinases 1 and 3, IL-8, human beta-defensin 4, and granzyme B. These data indicate a prominent role of matrix metalloproteinases, inflammatory cytokines, and antimicrobial peptides in acne lesions. These studies are the first describing the comprehensive changes in gene expression in inflammatory acne lesions and are valuable in identifying potential therapeutic targets in inflammatory acne.     

Levels of antibody to Staphylococcus epidermidis in patients with acne vulgaris.

Sera from 23 patients with acne vulgaris of varying degrees and sera from 15 patients with skin diseases other than acne were tested for antibody levels to Staphylococcus epidermidis by use of bacterial agglutination and agar-gel immunodiffusion. Antibody levels to S epidermidis varied from 0 to 1:160 in both the patients with acne and in the control groups. There was no correlation between the antibody level to S epidermidis and the degree of acne. In a previous investigation it was found that antibody levels to Corynebacterium acnes are significantly increased in serum from patients with papulopustular and cystic acne. Both S epidermidis and C acnes can frequently be isolated from lesions in acne. The fact that antibody levels are increased to C acnes but not to S epidermidis may indicate that the mere presence of an organism in the acne lesion is not sufficient stimulation for antibody formation. The increase of antibody to C acnes which was demonstrated previously in patients with severe acne vulgaris may therefore reflect a direct involvement of the organism in the acne process.     

Ocular surface disorders and tear function changes in nodulo-cystic acne

The aim of this study was to investigate the ocular surface disorders and tear function changes in patients with nodulo-cystic acne. Eighty-seven patients with nodulo-cystic acne vulgaris and 50 healthy subjects were included in the study. All subjects underwent full ocular examinations. Subjective ocular complaints were recorded. Corneal staining with fluorescein, tear film break-up time (BUT), and Schirmer test were applied. Abnormal tear film BUT and abnormal Schirmer scores were significantly more common in the acne group than in the control group. The tear film BUT was abnormal in 18 (20.7%) cases in the patient group and in 2 (4%) subjects in the control group (p=0.007). The mean Schirmer score was abnormal in 7 (8%) and decreased in 18 (20.7%) acne patients, and it was decreased in only 3 (6%) control subjects (p=0.005). Corneal punctuate epithelial erosions were detected in 3 (3.4%) acne patients, but not any of the control subjects. However, the difference between the groups was not statistically significant (p=0.184). Subjective ocular complaints were present in 28 cases (32.2%) in the patient group. Five (10%) subjects in the control group had such complaints (p=0.003). Tear function tests are also significantly altered in patients with nodulo-cystic acne. Our data suggest that severe acne patients should be referred to an ophthalmologist.     

Propionibacterium acnes: interaction with complement and development of an enzyme-linked immunoassay for the detection of antibody

OBJECTIVE: To characterize the immune response to Propionibacterium acnes in acne patients. DESIGN: Comparison of serologic responses in acne and normal patients using counterimmunoelectrophoresis for antibody and an enzyme-linked immunosorbent assay (ELISA) to detect immunoglobulin G (IgG) antibody. SETTING: The serum of acne and nonacne patients from the Dermatology Clinic at the Medical College of Ohio was utilized for analysis. RESULTS: Using counterimmunoelectrophoresis, antibody was detected in 13 of 20 acne patients. The antigen was detectable as an anion in the barbital buffer at pH 8.2, strongly suggesting a carbohydrate component. By ELISA, the antibody proved to be IgG, and the bacteria and its water-soluble fractions were capable of fixing complement. CONCLUSIONS: The primary instigator of inflammation in acne vulgaris is an immunologic reaction to extracellular products of P. acnes. The immunologic response involves both humoral and cell-mediated pathways. The antibodies to P. acnes have not been characterized fully, although they are largely of the IgG class. We have further characterized the dominant antigen to have a carbohydrate component.     

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.     

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.     

Delayed hypersensitivity and febrile acne conglobata.

Delayed hypersensitivity reactions were investigated in 5 patients with febrile acne conglobata. Each of them had febrile periods, large abscesses and leukocytosis. They reacted negatively to tuberculin 10 TU/ml, to Schick toxin, to oidiomycin, to trichophytin as well as to 25 common contact allergens. DNCB did not induce sensitization in those 4 patients in whom it was carried out. However, the transforamtion of lymphocytes by phytohaemagglutinin (PHA) was normal. Five of 7 control patients with cystic or ordinary acne had positive tuberculin test reactions and 3 of them were sensitized to DNCB.     

Antibody titers to Propionibacterium acnes cell wall carbohydrate in nodulocystic acne patients

In order to determine which structures in Propionibacterium acnes are most antigenic to severe acne patients, we studied the specificity of anti-P. acnes antibodies in serum from 15 nodulocystic acne patients and 5 normals. Complement fixation titers to P. acnes cell wall fractions were determined using guinea pig serum as a complement source. The mean titers of patients and normals to whole cells were 39.6 and 3 (p less than 0.1); to crude cell wall, 138 and 8 (p less than 0.01); and to protein and nucleic acid-free cell wall, 225 and 9.33 (p less than 0.001), respectively. The mean precipitin titer to P. acnes cytosol was 12.7 for patients and 0 for normals. Immunoelectrophoresis of cytosol from 8 P. acnes strains were developed with each of the 15 patient sera. A single broadly migrating anionic antigen was detected. The antigen was also present in P. acnes culture supernatants. Sephadex G-100 chromatography of cytosol revealed a single peak of antigenic reactivity at Mr = 100,000. Three patients' sera revealed a second weakly reacting antigen in the cytosol preparation. Twentyfold concentration of immunoglobulin from patient sera failed to reveal any other antigenic reactivities. The antigen was found to be resistant to nuclease, pronase, and lysozyme treatment; was precipitable with 70% ethanol; and was destroyed by sodium m-periodate--findings that are consistent with a carbohydrate structure.     

Acne: inflammation

The inflammatory stage of acne vulgaris is usually of greatest concern to the patient. A number of morphologically different inflammatory lesions may form that can be painful and unsightly. In 30% of patients, such lesions lead to scarring(1). Inflammatory acne and acne scarring can have significant psychological effects on the patient, including depression, anxiety, and poor self-image(2). Although inflammatory acne has been well characterized clinically, the mechanisms by which inflammatory lesions arise are still poorly understood. The human skin commensal bacterium, Propionibacterium acnes, has long been associated with inflammatory acne. This organism has been implicated over and above all of the other cutaneous microflora in contributing to the inflammatory response characteristic of acne. However, its precise role in the disease and its interaction with the human immune system remain to be elucidated.