Complement activation by Corynebacterium acnes

Complement Activation in Inflammatory Skin Diseases

The complement system is a fundamental part of the innate immune system, playing a crucial role in host defense against various pathogens, such as bacteria, viruses, and fungi. Activation of complement results in production of several molecules mediating chemotaxis, opsonization, and mast cell degranulation, which can contribute to the elimination of pathogenic organisms and inflammation. Furthermore, the complement system also has regulating properties in inflammatory and immune responses. Complement activity in diseases is rather complex and may involve both aberrant expression of complement and genetic deficiencies of complement components or regulators. The skin represents an active immune organ with complex interactions between cellular components and various mediators. Complement involvement has been associated with several skin diseases, such as psoriasis, lupus erythematosus, cutaneous vasculitis, urticaria, and bullous dermatoses. Several triggers including auto-antibodies and micro-organisms can activate complement, while on the other hand complement deficiencies can contribute to impaired immune complex clearance, leading to disease. This review provides an overview of the role of complement in inflammatory skin diseases and discusses complement factors as potential new targets for therapeutic intervention.

Microbial volatile compounds in health and disease conditions

Microbial cultures and/or microbial associated diseases often have a characteristic smell. Volatile organic compounds (VOCs) are produced by all microorganisms as part of their normal metabolism. The types and classes of VOC produced is wide, including fatty acids and their derivatives (e.g. hydrocarbons, aliphatic alcohols and ketones), aromatic compounds, nitrogen containing compounds, and volatile sulfur compounds. A diversity of ecological niches exist in the human body which can support a polymicrobial community, with the exact VOC profile of a given anatomical site being dependent on that produced by both the host component and the microbial species present. The detection of VOCs is of interest to various disciplines, hence numerous analytical approaches have been developed to accurately characterize and measure VOCs in the laboratory, often from patient derived samples. Using these technological advancements it is evident that VOCs are indicative of both health and disease states. Many of these techniques are still largely confined to the research laboratory, but it is envisaged that in future bedside 'VOC profiling' will enable rapid characterization of microbial associated disease, providing vital information to healthcare practitioners.

The production of inflammatory compounds by Propionibacterium acnes and other skin organisms

Culture supernatants from four species of skin microorganisms (P. acnes, P. avidum, P. granulosum and S. epidermidis) were assayed for smooth muscle contracting substances which are indicative of inflammatory activity. At least three types of smooth muscle contracting substances were detected. These were: first, a substance active on a rat fundic strip preparation and antagonized by N,N-DMT. Activity was enhanced when cultures were grown in the presence of tryptophan. This substance was probably tryptamine. Second, a substance active on a guinea-pig ileum preparation and antagonized by mepyramine. Activity was enhanced when cultures were grown in the presence of histidine. This substance was probably histamine. Third, a substance active on a rat fundic strip preparation but not antagonized by N,N-DMT, mepyramine, atropine or indomethacin. Activity was enhanced when cultures were grown in the presence of glucose. This activity was probably due to acetate, propionate or other short-chain fatty-acid salts. Chromatographic analysis confirmed the presence of histamine, tryptamine and short-chain fatty acids in the culture supernatants. These substances if produced in vivo may cause or contribute to inflammation and pain directly without the prior mediation of the immune system. Cell extracts of Propionibacterium species were analysed by bioassay for the presence of prostaglandin-like compounds. These could not be detected in any of the eight strains of organisms tested.

Cytotoxic activity of Propionibacterium acnes and other skin organisms

Culture supernatants from four species of skin micro-organisms were tested against VERO (monkey kidney cells) and skin fibroblasts for cytotoxic activity. Cytotoxic activity was produced by the three species of Propionibacterium tested (P. acnes, P. avidum and P. granulosum), and this activity was highest when cultures were grown in the presence of glucose. In contrast, Staphylococcus epidermidis was devoid of cytotoxic activity whether grown in the presence of glucose or not. The agent responsible for the cytotoxic activity was heat stable, of low molecular weight and removable from supernatants by ether extraction. These properties, coupled with the finding that the levels of cytotoxicity are directly proportional to the concentrations of propionate measured in samples, suggests that propionate is the agent responsible for the cytotoxicity of the culture supernatants. Pure propionate and the salts of other carboxylic acids (CI to C5) were tested at the same concentrations and showed different degrees of cytotoxicity depending on their chain length. Propionate may have an important role in the aetiology of the disease acne vulgaris.

Chemotactic efficiency of various chemoattractants for polymorphonuclear leukocytes in inflammatory acne vulgaris

The chemoattractant efficiencies of a Propionibacterium acnes (P. acnes) cell wall preparation, a P. acnes culture supernatant, and a soluble comedonal extract in the presence and absence of autologous serum for polymorphonuclear leukocytes (PMNs) have been compared in the present study. It has been found that all three preparations have no or very little chemotactic activity for PMNs in the absence of serum. In the presence of autologous serum chemotactic factors is generated by all preparations via the alternative complement pathway. The relative efficiencies of the various preparations to induce chemotactic factor by the alternate complement pathway has been evaluated. Based on the bacterial numbers of the original preparations from which the test preparations had been derived the comedonal extract appears to be more efficient in generating chemotactic factor than the other preparations. It is concluded that in vivo generation of chemotactic factors occurs mainly via the alternate complement pathway activated by soluble comedonal factors diffusing through the follicular wall.

Bacteriologic and serologic investigation in diffuse sclerosing osteomyelitis (DSO) of the mandible

An attempt was made to clarify the obscure origin of diffuse sclerosing osteomyelitis (DSO) of the mandible. Bacteriologic investigations of specimens from diseased mandibles were performed with special attention to anaerobic culture technique. Propionibacterium acnes and Peptostreptococcus intermedius were in some patients found to be of etiologic importance. Sampling techniques and associated problems are discussed. An examination was made for antibodies in the patients' sera against antigens prepared from bacterial isolates. ASTA, IgM, IgG, and IgA were determined. Lymphocyte-stimulation tests were performed. The inflammatory events and chronicity of the disease could not be explained by the immunologic findings.

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

Propionibacterium 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 popular 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 of the acne. These findings indicate that the host response to P. acnes is an important variable in determining the severity of inflammatory acne.

Characterization of serum-independent polymorphonuclear leukocyte chemotactic factors produced by Propionibacterium acnes

The size and production of polymorphonuclear leukocyte (PMN) chemotactic factors by Propionibacterium acnes has been studied. All eight strains of P. acnes which were tested liberated PMN chemotactic factors in their growth culture media. The factor(s) produced by one strain, 6919, were studied in greater depth. The PMN response was proportional to the dose of culture supernatant and chemotactic activity increased with the duration of P. acnes culture. The neutrophil migration towards culture supernatants was chemotactic, with a slight stimulation of random migration by 72-h supernatants. The size of the chemotactic molecules was studied through dialysis, ultrafiltration, and Sephadex G-25 chromatography of 72-h supernatants. Low-molecular-weight chemotactic factors were found to be predominant by each method of size determination.

Polymorphonuclear leukocyte lysosomal release in response to Propionibacterium acnes in vitro and its enhancement by sera from inflammatory acne patients

Propionibacterium acnes cells were tested for the ability to trigger lysosomal hydrolase release from human polymorphonuclear leukocytes. Representative strains of P. acnes serotype I and II failed to stimulate lysosomal release in the absence of serum. P. acnes growth culture supernatants failed to trigger release under any test condition. Addition of fresh or heat-inactivated human serum resulted in lysosomal hydrolase release directly proportional to the number of P. acnes/PMN. Pooled sera from acne patients, with a high anti-P. acnes titer stimulated release to P. acnes. Preabsorption of this reagent with P. acnes cells reduced the anti-P. acnes titer and produced 93.37 +/- 11.49% inhibition of lysosomal enzyme release compared to unabsorbed anti-serum. Electron microscopy indicated that P. acnes was readily phagocytosed by PMNs when fresh or heated serum was present.

Neutrophil chemotaxis induced by anaerobic bacteria isolated from necrotic dental pulps

Anaerobic bacteria belonging to the species Bacteroides melaninogenicus, Bacteroides asaccharolyticus, Fusobacterium nucleatum, Peptostreptococcus anaerobius and Eubacterium alactolyticum, isolated from necrotic dental pulps, were tested for their capacity to induce neutrophil leukocyte chemotaxis. Generation of chemotactic factors in serum by whole bacterial cells and chemotaxis induced by bacterial extracts were studied in vitro by the Boyden technique. Subcutaneously implanted wound chambers in guinea pigs were used for testing leukocyte migration in vivo. All bacterial strains had a similar high capacity to induce neutrophil chemotaxis. The heavy accumulation of polymorhponuclear neutrophil leukocytes associated with clinical and experimental infections by B. melaninogenicus or B. asaccharolyticus cannot be ascribed to any extreme ability of these organisms to generate chemotactic factors.

Activation of the alternative pathway of complement by Malassezia ovalis (Pityrosporum ovale)

Activation of C3 and factor B in normal human serum by P. ovale was demonstrated using a standard unidirectional immunoelectrophoresis technique. Activation of complement by the alternative (properdin) pathway is a possible mechanism by which P. ovale may mediate an inflammatory response.

Complement C3 and immunoglobulin in inflammatory acne vulgaris

In patients with moderate to severe inflammatory acne, complement (C3) was detected by immunofluorescence in sixteen early inflammatory acne lesions but in only one of thirteen biopsies of non-inflamed skin from acne sites. C3 deposition occurred particularly in the walls of small dermal blood vessels and at the dermo-epidermal junction. IgM was identified in vessel walls in four of sixteen early lesions. In eight late inflammatory lesions C3 deposition was much less prominent and was present in vessel walls in only two. None of the late lesions showed vascular deposition of IgM. The observations indicate that complement activation occurs in inflammatory acne and it is suggested that this may play a pathogenic role in the inflammation.

Activation of complement-a mechanism for the inflammation in acne

An immunofluorescence investigation of thirty-six non-inflamed and thirty-four inflamed acne lesions has been carried out. Fluorescence for C3, unaccompanied by fluorescence for immunoglobulins, was found in the walls of dermal blood vessels or at the basement membrane zone of the comedo or at both these sites in fifty-seven lesions. Fluorescence for C3 accompanied by fluorescence for immunoglobulins was found in nine lesions. In two papules and three nodules the comedo was surrounded or replaced by a mononuclear cell infiltrate. These findings have been taken to indicate that cellular immune mechanisms are a late event and activation of complement is an early event in the pathogenesis of inflammation in acne. The mechanism of complement activation remains uncertain.