In vivo and in vitro effect of killed Propionibacterium acnes and its purified soluble polysaccharide on mouse bone marrow stem cells and dendritic cell differentiation

Among the effects exerted by Propionibacterium acnes, a most relevant one is its capacity to modulate the Th1/Th2 cellular immune response. This effect depends on the induction and activation of antigen presenting cells, mainly dendritic cells (DCs), whose number is increased in the peripheral blood of animals treated with this bacterium. A soluble P. acnes polysaccharide (PS) extract also acts on DCs, modulating a Th1 immune response. These data led us to investigate the role of P. acnes and its soluble PS on murine bone marrow (BM) DCs. Bone marrow cells were analyzed by flow cytometry, showing an increase of stem cells and DCs in P. acnes- or PS-treated animals. Culturing in the presence of granulocyte monocyte colony stimulating factor (GM-CSF) increased the in vitro differentiation and maturation of these cells into BM-derived DCs (CD11c+ and MHC class II+). Maturation of DCs was determined by increased CD80 and CD86 expression, IL-4 and IL-12 production, reduction in phagocytic capacity and increase in the antigen presenting ability to primed or naïve T lymphocytes. These data indicate that P. acnes as well as its PS can modulate BM stem cells, originating mature DCs, which are important mainly at the initial antigen contact.

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.

Involvement of neutrophil recruitment and protease-activated receptor 2 activation in the induction of IL-18 in mice

Activated neutrophils produce serine proteases, which activate cells through protease-activated receptor 2 (PAR2). As proteinase 3 (PR3) induces the secretion of interleukin (IL)-18 from epithelial cells in combination with lipopolysaccharide (LPS) in vitro, we examined whether neutrophils, serine proteases, and PAR2 are involved in the induction of serum IL-18 and IL-18-dependent liver injury in mice treated with heat-killed Propionibacterium acnes and LPS. LPS-induced serum IL-18 levels in P. acnes-primed mice were reduced significantly by anti-Gr-1 injection (depletion of neutrophils and macrophages) but not by a macrophage "suicide" technique, using liposomes encapsulating clodronate. The IL-18 induction was decreased significantly by coadministration of a serine protease inhibitor [Nafamostat mesilate (FUT-175)] with LPS. Serum levels of tumor necrosis factor alpha and liver enzymes induced by P. acnes and LPS were abolished by anti-Gr-1 treatment, and concomitantly, liver injury (necrotic change and granuloma formation) and Gr-1(+) cell infiltration into the liver were prevented by the treatment. A deficiency of PAR2 in mice significantly impaired IL-18 induction by treatment with P. acnes and LPS, and only slight pathological changes in hepatic tissues occurred in the PAR2-deficient mice treated with P. acnes and LPS. Furthermore, coadministration of exogenous murine PR3 or a synthetic PAR2 agonist (ASKH95) with LPS in the anti-Gr-1-treated mice restored the serum IL-18 levels to those in control mice treated with P. acnes and LPS. These results indicate that neutrophil recruitment and PAR2 activation by neutrophil serine proteases are critically involved in the induction of IL-18 and IL-18-dependent liver injury in vivo.

Induction of a chemoattractive proinflammatory cytokine response after stimulation of keratinocytes with Propionibacterium acnes and coproporphyrin III

BACKGROUND

The inflammation in acne vulgaris is widely thought to be induced by an immunological reaction, but the role of Propionibacterium acnes is unclear.

OBJECTIVES

To examine the local host response mechanism of a keratinocyte cell line 3 h and 6 h after stimulation with viable and heat-killed P. acnes.

METHODS

The quantitative expression of cytokines was measured at the mRNA level by real-time reverse transcription-polymerase chain reaction.

RESULTS

The coincubation of a keratinocyte cell line with viable, but not heat-killed, P. acnes modulated an adequate cytokine response for interleukin (IL)-1beta, granulocyte/macrophage colony-stimulating factor and IL-8. High-performance liquid chromatographic analysis of the in vivo porphyrin pattern secreted by P. acnes revealed a predominance of coproporphyrin III in acne lesions. This same porphyrin fraction also modestly induced IL-8 expression by keratinocytes.

CONCLUSIONS

This cytokine pattern may favour a chemotactic response and implicates P. acnes and coproporphyrin III in the recruitment of inflammatory cells to the site of infection and in the development of acne lesions.

Exacerbation of granuloma formation in IL-1 receptor antagonist-deficient mice with impaired dendritic cell maturation associated with Th2 cytokine production

Dendritic cell (DC) maturation at the site of inflammation and migration into draining lymph nodes is fundamental to initiate Ag-specific immune responses. Although several proinflammatory cytokines, including IL-1, are known to promote DC maturation in vitro, their contributions to DC activation and migration within peripheral inflamed tissue compartments are not yet fully understood. We show here that endogenous IL-1 receptor antagonist (IL-1ra) controls the activation state of liver-recruited DCs and their migration in a Propionibacterium acnes-induced murine granulomatous liver disease model. After P. acnes treatment, formation of portal tract-associated lymphoid tissue was conversely impaired in IL-1ra-deficient mice. IL-1ra-deficient mice developed hepatic granulomas within 3 days after P. acnes administration and showed a more pronounced granuloma formation than wild-type mice. Although sinusoidal granulomas contained numerous CD11c+ DCs at day 7, expressions of CCR7, IL-12p40 by these DCs were dramatically decreased in IL-1ra-deficient mice, suggesting aberrant DC maturation and sinusoid portal migration in the absence of endogenous IL-1ra. This was accompanied with enhanced intrahepatic Th2 cytokine production and severe hepatocellular damage. Thus, hepatocyte-derived IL-1ra may control optimal activation and migration of inflammatory DCs within the liver and thereby determine the local immune responses in granulomatous liver disease.

Requirement for TLR9 in the Immunomodulatory Activity ofPropionibacterium acnes

Propionibacterium acnes (formerly Corynebacterium parvum) is part of the human flora and, as such, is associated with several human pathologies. It possesses strong immunomodulatory activities, which makes this bacterium interesting for prophylactic and therapeutic vaccination. The bacterial component(s) and the host receptor(s) involved in the induction of these activities are poorly understood. We show in this study that TLR9 is crucial in generating the characteristic effects of killed P. acnes priming in the spleen, such as extramedullary hemopoiesis and organ enlargement, and granuloma formation in the liver. Furthermore, the ability to overproduce TNF-alpha and IFN-gamma in response to LPS, lipid A, synthetic lipopeptide Pam(3)CysK(4), or whole killed bacteria was present in P. acnes-primed wild-type, but not TLR9(-/-), mice. Finally, P. acnes priming failed to induce enhanced resistance to murine typhoid fever in TLR9(-/-) mice. Thus, TLR9 plays an essential role in the induction of immunomodulatory effects by P. acnes. Because IFN-gamma is a key mediator of these effects, and enhanced IFN-gamma mRNA expression was absent in spleen and liver of P. acnes-primed TLR9(-/-) mice, we conclude that TLR9 is required for the induction of IFN-gamma by P. acnes.

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.

The potential immunomodulatory effects of topical retinoids

New research has refined our understanding of the immunopathophysiology of acne. Various immune factors, including both innate and adaptive immune responses, have been implicated in the pathophysiology of inflammatory acne. Topical retinoids such as tretinoin, adapalene, and tazarotene, exhibit immunomodulatory effects that may help to explain their efficacy in the resolution of inflammatory lesions.

Propionibacterium acnes types I and II represent phylogenetically distinct groups

Although two phenotypes of the opportunistic pathogen Propionibacterium acnes (types I and II) have been described, epidemiological investigations of their roles in different infections have not been widely reported. Using immunofluorescence microscopy with monoclonal antibodies (MAbs) QUBPa1 and QUBPa2, specific for types I and II, respectively, we investigated the prevalences of the two types among 132 P. acnes isolates. Analysis of isolates from failed prosthetic hip implants (n = 40) revealed approximately equal numbers of type I and II organisms. Isolates from failed prosthetic hip-associated bone (n = 6) and tissue (n = 38) samples, as well as isolates from acne (n = 22), dental infections (n = 8), and skin removed during surgical incision (n = 18) were predominately of type I. A total of 11 (8%) isolates showed atypical MAb labeling and could not be conclusively identified. Phylogenetic analysis of P. acnes by nucleotide sequencing revealed the 16S rRNA gene to be highly conserved between types I and II. In contrast, sequence analysis of recA and a putative hemolysin gene (tly) revealed significantly greater type-specific polymorphisms that corresponded to phylogenetically distinct cluster groups. All 11 isolates with atypical MAb labeling were identified as type I by sequencing. Within the recA and tly phylogenetic trees, nine of these isolates formed a cluster distinct from other type I organisms, suggesting a further phylogenetic subdivision within type I. Our study therefore demonstrates that the phenotypic differences between P. acnes types I and II reflect deeper differences in their phylogeny. Furthermore, nucleotide sequencing provides an accurate method for identifying the type status of P. acnes isolates.

Cutting Edge: All-transRetinoic Acid Down-Regulates TLR2 Expression and Function

A major consequence of microbial infection is the tissue injury that results from the host inflammatory response. In acne, inflammation is due in part to the ability of Propionibacterium acnes to activate TLR2. Because all-trans retinoic acid (ATRA) decreases inflammation in acne, we investigated whether it regulates TLR2 expression and function. Treatment of primary human monocytes with ATRA led to the down-regulation of TLR2 as well as its coreceptor CD14, but not TLR1 or TLR4. The ability of a TLR2/1 ligand to trigger monocyte cytokine release was inhibited by pre- and cotreatment with ATRA; however, TLR4 activation was affected by cotreatment only. ATRA also down-regulated monocyte cytokine induction by P. acnes. These data indicate that ATRA exerts an anti-inflammatory effect on monocytes via two pathways, one specifically affecting TLR2/1 and CD14 expression and one independent of TLR expression. Agents that target TLR expression and function represent a novel strategy to treat inflammation in humans.

Involvement of CD14 in lipopolysaccharide- induced liver injury in mice pretreated with Propionibacterium acnes

OBJECTIVE

The aim of this study was to elucidate the role of CD14 in the Propionibacterium acnes-lipopolysaccharide (LPS) system.

METHODS AND RESULTS

CD14 transgenic mice (M14M), which expressed heterotopic CD14 and showed decreased responses to LPS in vivo, were used. Seven days after priming, the size of granulomas induced by an intraperitoneal administration of P. acnes in the M14M mice was smaller than that in the nontransgenic mice. The number of CD14-positive cells in granulomas was also decreased in the M14M mice compared to the nontransgenic mice. An LPS challenge induced apoptotic and necrotic changes in hepatocytes in the nontransgenic mice but not in the M14M mice. Seven days after priming, tumor necrosis factor-alpha expression was found in monocytic cells in granulomas and Kupffer cells in the nontransgenic mice and was significantly upregulated after LPS injection, whereas the expression was very weak in these cells in the M14M mice.

CONCLUSIONS

CD14 plays a role in the P. acnes-LPS system in both priming and induction phases.

Enhanced resistance to Gram-positive bacterium and increased susceptibility to bacterial endotoxin in mice sensitized withPropionibacterium acnes: involvement of Toll-like receptor

Mice sensitized with Propionibacterium acnes showed an enhanced resistance against infection with Listeria monocytogenes in contrast to the increased susceptibility to LPS-induced endotoxin shock. The enhanced protection to L. monocytogenes was mediated by activated innate immunity but not by generation of Listeria-specific acquired immunity. After infection with L. monocytogenes, the elimination of bacteria was observed earlier in accordance with a higher level of endogenous cytokine production in P. acnes-sensitized mice than in control mice. Peritoneal cells from P. acnes-sensitized mice produced a larger amount of IL-12p70 and nitric oxide after stimulation with heat-killed L. monocytogenes or peptidoglycan purified from Staphylococcus aureus. RT-PCR analysis showed that the expression of TLR2 but not TLR1, TLR4 nor TLR6 was induced by injection of P. acnes in peritoneal cells. These results indicated that P. acnes-sensitization could induce the activation of innate immunity against L. monocytogenes through increased recognition of bacterial components by TLR2.

TLR Ligands Can Activate Dendritic Cells to Provide a MyD88-Dependent Negative Signal for Th2 Cell Development

During infection, CD4(+) Th cell responses polarize to become primarily Th1 or Th2. Th1 cells, which make IFN-gamma, are crucial for immunity to many bacterial and protozoal infections, whereas Th2 cells, which make IL-4, IL-5, and IL-13, are important for resistance to helminth infections. Polarized Th1 responses are induced by dendritic cells (DCs), which respond to pathogen-derived TLR ligands to produce IL-12 and related cytokines that are instrumental in Th1 cell outgrowth, and coordinately process and present Ag in the context of MHC class II to activate naive Th cells. In this study we show that in addition to providing positive signals for Th1 cell development, mouse DCs activated by TLR engagement can also provide a potent negative signal that prevents the development of Th2 cells. Production of this signal, which is not IL-12, IL-18, IL-23, IL-27, or IFN-gamma and is not provided via Th1 cells, is dependent upon a MyD88-dependent, TNF receptor-associated factor-6-independent signaling pathway in DCs. The signal is released from DCs in response to activation via TLR ligands and exerts an effect directly on Th cells rather than through a third-party cell. Our findings indicate that DCs can provide potent negative as well as positive instruction for Th response polarization, and that these instructional signals are distinct and independent.

Different pro-inflammatory and immunogenic potentials of Propionibacterium acnes and Staphylococcus epidermidis: implications for chronic inflammatory acne

INTRODUCTION

Propionibacterium acnes (PA) and Staphyloccocus epidermidis (SE) are two major bacterial strains isolated from acne lesions. Nevertheless, only PA seems to be implicated in the pathogenesis of inflammatory acne vulgaris. Evidence for this, however, remains indirect and the precise role of PA in inflammatory acne is still a matter for conjecture. The aim of this study was to compare some pro-inflammatory and adjuvant properties of PA and SE.

MATERIAL/METHODS

To determine some of the pathogenic, immunostimulatory, and pro-inflammatory proper of PA and SE, two experimental models of inflammation were used. In vivo; chronic inflammation was induced by intradermal injection of living bacteria into the ear. In vitro; peritoneal macrophages elicited by the bacteria were examined for their ability to generate reactive oxygen species (ROS), nitric oxide (NO), and cytokines.

RESULTS

PA, but not SE, evoked mild local inflammation of infected ears. Macrophages elicited with PA produced more tumor necrosis factor alpha and interleukin IL-12 than those induced with SE, while SE was a stronger inducer of IL-10 production. Both bacteria equally induced the generation of NO and ROS. In contrast, only PA showed adjuvant proper-ties.

CONCLUSIONS

The results of these studies indicate that SE, in contrast to PA, does not exert pro-inflammatory properties. Thus it is unlikely that SE may be implicated in the pathogenesis of inflammatory acne vulgaris.

Increased interleukin-10 associated with low IL-6 concentration correlated with greater survival rates in mice infected by rabies virus vaccinated against it and immunomodulated with P. acnes

Macrophage activity, cytokines serum concentration, serum neutralizing antibodies and lethality by rabies were evaluated in swiss mice experimentally infected with street rabies virus and submitted or not to antirabies vaccination and immunomodulation with P. acnes. Animals were killed at different times and serum was collected in order to evaluate cytokines concentration; peritonial and splenic macrophages were collected for macrophage activity evaluation. Greater survival rates higher IL-10 and low IL-6 serum concentration were observed in vaccinated animals treated using P. acnes.

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.

Selective priming to Toll-like receptor 4 (TLR4), not TLR2, ligands by P. acnes involves up-regulation of MD-2 in mice

Lipopolysaccharide (LPS) triggers cytokine production through Toll-like receptor 4 (TLR4), which shares downstream signaling pathways with TLR2. We investigated the roles of TLR2 and TLR4 in Propionibacterium acnes (P. acnes)-primed, LPS-induced liver damage using selective TLR ligands. Stock LPS induced interleukin 8 in both TLR4- and TLR2-expressing human embryonic kidney (HEK) 293 cells. Purified LPS (TLR4 ligand) activated HEK/TLR4 cells, while peptidoglycan and lipoteichoic acid (TLR2 ligands) activated HEK/TLR2 cells, respectively. In mice, P. acnes priming resulted in increased liver messenger RNA (mRNA) and serum levels of tumor necrosis factor alpha, interleukin 12, and interferon gamma (IFN-gamma) by both stock LPS and purified LPS challenges compared with nonprimed controls. In contrast, P. acnes failed to sensitize to TLR2 ligands (peptidoglycan + lipoteichoic acid). In the liver, P. acnes-priming was associated with up-regulation of TLR4 and MD-2 proteins, and subsequent LPS challenge further increased MD-2 and CD14 mRNA levels. The lack of sensitization to TLR2 ligands by P. acnes correlated with no increase in hepatic TLR1 or TLR6 mRNA. In vitro, P. acnes pretreatment desensitized RAW macrophages to a secondary stimulation via both TLR2 and TLR4. However, IFN-gamma could selectively prevent desensitization to TLR4 but not to TLR2 ligands. Furthermore, P. acnes induced production of IFN-gamma in vivo as well as in isolated splenocytes. In vitro, P. acnes-primed Hepa 1-6 hepatocytes but not RAW macrophages produced increased MD-2 and CD14 mRNA levels after an LPS challenge. In conclusion, P. acnes priming to selective TLR4-mediated liver injury is associated with up-regulation of TLR4 and MD-2 and is likely to involve IFN-gamma and prevent TLR4 desensitization by P. acnes.

Indigenous pulmonary Propionibacterium acnes primes the host in the development of sarcoid-like pulmonary granulomatosis in mice

Although many cases of sarcoidosis are self-limiting with spontaneous remission, uncontrolled pulmonary granulomatosis with fibrosis produces intolerable long-term respiratory symptoms in a minority of patients. Individuals with chronic pulmonary sarcoidosis require an alternative therapy to corticosteroidal treatment because of its insufficient effectiveness. Although many researchers have considered infection as the triggering factor for this disease, the mechanisms by which the candidate causative organisms induce this disorder remain unclear. We report here that extrapulmonary sensitization to Propionibacterium acnes, which is one of the candidates to date, induced pulmonary Th-1 granulomas mainly in the subpleural and peribronchovascular regions often observed in sarcoidosis. These granulomas appear to be caused by indigenous P. acnes pre-existing in the lower respiratory tract of the normal lung, which is believed to be germ-free, and by an influx of P. acnes-sensitized CD4(+) T cells from the circulation. Importantly, the eradication of indigenous P. acnes with antibiotics alleviated the granulomatous lung disease. This is the first report to present clear evidence of the contribution of an indigenous pulmonary bacterium to the formation of granulomatous lesions in the lung. We propose that treatment targeting indigenous P. acnes in the lung may be a possible remedy for pulmonary sarcoidosis.

The Complete Genome Sequence of Propionibacterium Acnes, a Commensal of Human Skin

Propionibacterium acnes is a major inhabitant of adult human skin, where it resides within sebaceous follicles, usually as a harmless commensal although it has been implicated in acne vulgaris formation. The entire genome sequence of this Gram-positive bacterium encodes 2333 putative genes and revealed numerous gene products involved in degrading host molecules, including sialidases, neuraminidases, endoglycoceramidases, lipases, and pore-forming factors. Surface-associated and other immunogenic factors have been identified, which might be involved in triggering acne inflammation and other P. acnes-associated diseases.

Evidence for recruitment of plasmacytoid dendritic cell precursors to inflamed lymph nodes through high endothelial venules

Recruitment of dendritic cells (DCs) to lymph nodes (LNs) is pivotal to the establishment of immune response. Whereas DCs have been proven to undergo afferent lymphatic pathway to enter LNs from peripheral tissues, a question remains if DCs also migrate into LNs directly from the circulation. Here we demonstrate that plasmacytoid DC (pDC) precursors can transmigrate across high endothelial venules (HEVs) of inflamed LNs in mice. Bacterial infection induces a significant number of pDC and myeloid DC (mDC) precursors into the circulation. Both subsets express a common set of chemokine receptors except CXCR3, display parallel mobilization into the blood, but show distinct trafficking pathway to the LNs. In a short-term homing assay, whereas mDC precursors migrate to peripheral tissues and subsequently to draining LNs, pDC precursors directly enter the LNs in a CXCL9 and E-selectin dependent manner. Tumor necrosis factor-alpha controls not only DC precursor mobilization into the blood but also chemokine up-regulation on LN HEVs. A similar trafficking pathway is observed also in viral infection, and CXCR3(-/-) mice-derived pDC precursors show defective trans-HEV migration. This study clarifies the inflammation-dependent, chemokine-driven distinct property of DC precursor trafficking.

Antibody response to crude cell lysate of propionibacterium acnes and induction of pro-inflammatory cytokines in patients with acne and normal healthy subjects

Propionibacterium acnes (P. acnes) plays an important role in the disease pathogenesis of acne vulgaris, a disorder of pilosebaceous follicles, seen primarily in the adolescent age group. In the present study, the presence of antibodies against P. acnes (MTCC1951) were detected in acne patient (n=50) and disease free controls (n=25) using dot-ELISA and Western blot assay. The ability of P. acnes to induce pro-inflammatory cytokines by human peripheral blood mononuclear cells (PBMCs), obtained from acne patients and healthy subjects, were also analysed. The patients (n=26) who were culture positive for skin swab culture, were found to have a more advanced disease and higher antibody titres (1:4000 to > 1:16000) compared to the P. acnes negative patients (n=24) and normal controls (n=25). An analysis of patients' sera by western blot assay recognized a number of antigenic components of P. acnes, ranging from 29 to 205 kDa. The major reactive component was an approximately 96 kDa polypeptide, which was recognised in 92% (24 of 26) of the patients sera. Further, the P. acnes culture supernatant, crude cell lysate and heat killed P. acnes whole cells, obtained from 72-h incubation culture, were observed to be able to induce significant amounts of IL-8 and tumor necrosis factor alpha (TNF-alpha) by the PBMCs in both the healthy subjects and patients, as analysed by cytokine-ELISA. The levels of cytokines were significantly higher in the patients than the healthy subjects. A major 96 kDa polypeptide reactant was eluted from the gel and was found to cause dose dependent stimulation of the productions of IL-8 and TNF-alpha. Thus, the above results suggest that both humoral and pro-inflammatory responses play major roles in the pathogenesis of acne.

Cutting Edge: Dendritic Cells Copulsed with Microbial and Helminth Antigens Undergo Modified Maturation, Segregate the Antigens to Distinct Intracellular Compartments, and Concurrently Induce Microbe-Specific Th1 and Helminth-Specific Th2 Responses

To examine the ability of dendritic cells (DC) to discriminate between helminth and microbial Ag and induce appropriately polarized Th responses, mouse DC were copulsed with the helminth Ag, schistosome egg Ag (SEA), along with the bacterium Proprionebacterium acnes, Pa, and transferred into wild-type mice. Strikingly, SEA/Pa-copulsed DC induced concurrent Pa-specific Th1 (but not Th2) responses and SEA-specific Th2 (but not Th1) responses. Although DC exposed to both Ag undergo many of the maturation-associated changes that accompany exposure to Pa alone, Pa-induced IL-12 production was inhibited by SEA. Examination of Ag uptake revealed that SEA and Pa are acquired via discrete pathways and enter nonoverlapping intracellular compartments. Data suggest that segregation of SEA and Pa into distinct compartments, coupled with SEA-induced modifications of the DC maturation pathway, are significant components of the ability of DC to interpret signals inherent to SEA and Pa and induce appropriately polarized Th responses.

Pulmonary granulomas caused experimentally in mice by a recombinant trigger-factor protein of Propionibacterium acnes

Etiology of sarcoidosis remains unknown. A trigger factor from Propionibacterium acnes causes a cellular immune response in some sarcoid patients but not in nonsarcoid subjects. We examined whether experimentally induced hypersensitivity to the trigger factor gives rise to granulomas. Female C57BL/6 mice primed intravenously with P. acnes or not were sensitized with recombinant-protein RP35, a fragment of P. acnes trigger factor, and complete Freund's adjuvant. In controls, RP35 was replaced with P. acnes or one of two control proteins. In primed and unprimed mice, pulmonary granulomas were found in some of the mice sensitized with RP35 or P. acnes but in no control-protein-sensitized mice. Detection of pulmonary granulomas (25-57%) did not differ significantly between mice sensitized with RP35 or P. acnes, primed or not. No difference in popliteal lymph-node-cell reactivity and serum antibodies to these two antigens was found between mice with and without pulmonary granulomas. P. acnes was cultured from the lungs of 8 (33%) of 24 untreated mice. The recombinant trigger-factor protein of P. acnes caused pulmonary granulomas in primed and unprimed mice sensitized with the protein and adjuvant. Sarcoid granulomas may form during hypersensitivity to antigens of P. acnes indigenous to the affected organ.

TNF revisited: TNF-independent antitumor activity in sera of mice sensitized with Propionibacterium acnes and challenged with lipopolysaccharide

Sera of mice sensitized with bacteria and subsequently challenged with lipopolysaccharide promote hemorrhagic necrosis of tumors in vivo and display cytotoxic activity against tumor cells in vitro, which has been attributed to the induction of tumor necrosis factor (TNF). Here, we describe the induction of a previously unrecognized antitumor activity in such sera, which is distinct from TNF but displays tumor-specific cytocidal activity in vitro as well as potent tumor-regressing activity in vivo. Biochemical analysis of this activity yielded a molecular mass of approximately 150 kDa, closely resembling a novel tumoricidal factor of murine macrophages (Mphi) termed MTC 170 (Mphi tumor cytotoxin, approximate molecular mass 170 kDa), which we have previously proposed to constitute a major effector pathway for the destruction of tumor cells by activated Mphi.

Treatment with Propionibacterium acnes modulates the late phase reaction of immediate hypersensitivity in mice

The administration of killed Propionibacterium acnes suspension to mice enhances macrophage phagocytic and tumoricidal activities, have an adjuvant effect to antibody response and increases resistance to infection. Recent reports demonstrated that P. acnes treatment promotes IL-12 and IL-18 synthesis in mice inducing IFN-gamma release, enhancement of IgG2a switch and inhibition of Th2 cell expansion. These findings led us to investigate whether P. acnes could modulate hypersensitivity type I reaction observed in a murine model. Animals were implanted with heat coagulated hen's egg white (HEW) into the subcutaneous tissue, followed by OVA-challenge in the footpad. The observed reaction was characterized by elevated Th2 cytokine levels, especially IL-4 and increase in eosinophil infiltration as occurs in the late phase reaction (LPR) of type I hypersensitivity, a pattern observed in allergic asthma in human. Two different biological effects were induced by killed P. acnes depending on the experimental protocol used. When mice were treated with one dose of P. acnes per week during 3 weeks and the last dose administrated at the same time of HEW implantation, a strong adjuvant effect on type I hypersensitivity reaction with intense eosinophilic infiltration was observed. On the other hand, when the HEW implant was made 1 week after the administration of the last dose of P. acnes, animals developed a typical delayed type hypersensitivity reaction, and a cytokines pattern characteristic of the Th1 immune response.

Increases in cytokine and antimicrobial peptide gene expression in horses by immunomodulation with Propionibacterium acnes

Immunomodulation with Propionibacterium acnes is used for prophylaxis of respiratory disease or in horses suffering from chronic pulmonary inflammation; however, the mechanism for this response is poorly understood. Semiquantitative reverse transcriptase-polymerase chain reaction assays were used to evaluate gene expression of interleukin (IL)-2, IL-10, interferon (IFN)-gamma, and NK-lysin in healthy horses treated with P. acnes. Findings in the study indicated that horses treated with a P. acnes-based immunomodulator exhibited increased IFN-gamma and NK-lysin gene expression in peripheral blood mononuclear cells. These results suggest that part of the immunostimulating properties of a P. acnes-based immunomodulator is derived from enhanced gene expression of the type-1 cytokine IFN-gamma and NK-lysin, an antimicrobial peptide.

The role of innate immunity in the pathogenesis of acne

Acne is a multifactorial disease of the pilosebaceous follicle. The most significant pathogenetic factors of acne are: abnormal ductal keratinization, increased sebum secretion, abnormalities of the microbial flora and inflammation. The pilosebaceous unit is an immunocompetent organ. Keratinocytes and sebocytes may act as immune cells capable of pathogen recognition and abnormal lipid presentation, and they might have an important role in initiating and perpetuating the activation of both innate and adaptive immune responses. The elements of the skin immune system are involved in the development of both noninflammatory and inflammatory acne lesions.

Identification and purification of immunogenic proteins from nonliving promastigote polyvalent Leishmania vaccine (Leishvacin )

Immunogenic proteins from nonliving promastigote polyvalent Leishmania vaccine against American tegumentary leishmaniasis (Leishvacin ), produced by Biobr s (Biochemistry of Brazil ), Montes Claros, State of Minas Gerais, Brazil, were identified and purified by polyacrylamide electrophoresis gel and electroelution. C57BL/10 mice were vaccinated with proteins with estimated molecular weights of 42, 46, 63, 66, 73, 87, 97, and 160kDa in three doses of 30 g of each protein at 15-day intervals combined with 250 microg of Corynebacterium parvum followed by a challenge infection with 10(5) infective promastigotes from Leishmania (Leishmania) amazonensis. The ability of these proteins to induce immune response and protection was analyzed. No statistical difference was observed in the level of IFN-gamma induced by proteins in vaccinated groups in comparison with control groups. Six months after challenge infection, protection levels of 28.57; 42.86; 57.14; 42.86; 42.86, 57.14; 42.86 and 57.14% were demonstrated for each purified protein.

Anti-inflammatory effects of erythromycin and tetracycline on Propionibacterium acnes induced production of chemotactic factors and reactive oxygen species by human neutrophils

Propionibacterium acnes (P. acnes), an anaerobic pathogen, plays an important role in the pathogenesis of acne and seems to initiate the inflammatory process by producing neutrophil chemotactic factors (NCF). Once neutrophils attracted by bacterial chemoattractants reach the inflamed site, they release inflammatory mediators such as lysosomal enzymes and reactive oxygen species (ROS). Previously, it has been shown that antibiotics may affect acne by means other than their anti-bacterial effects. Thus, we investigated the effect of subminimal inhibitory concentration (sub-MIC) of tetracycline and erythromycin on production of NCF and ROS. NCF was tested in vivo in a mouse model and ROS was estimated on human PMNL in vitro, by nitroblue tetrazolium dye reduction test (NBT) and cytochrome-C reduction test. Tetracycline (CS-T) and Erythromycin (CS-E) treated cultures showed a significant reduction of 35.8% and 58.3% in NCF production respectively, as compared to P. acnes stimulated cultures. Tetracycline and erythromycin at their sub-MIC also significantly inhibited release of ROS from human PMNL. Thus, tetracycline and erythromycin, besides having antibacterial activity, also have an anti-inflammatory action. These antibiotics reduce the capacity of P. acnes to produce NCF, as well decrease its ability to induce ROS from PMNL.

Beneficial or deleterious effects of a preexisting hypersensitivity to bacterial components on the course and outcome of infection

Priming with heat-killed Propionibacterium acnes enhances the sensitivity of mice to lipopolysaccharide (LPS) and other biologically active bacterial components. We show that P. acnes priming has protective and deleterious effects on a subsequent serovar Typhimurium infection. It may result in a complete protection or prolonged survival, or it may accelerate mortality of the infected mice, depending on the number of serovar Typhimurium bacteria administered and on the degree of LPS hypersensitivity at the time of infection. Both effects of P. acnes-induced hypersensitivity are mediated by gamma interferon (IFN-gamma) and are based on a differential activation of the innate immune mechanisms which recognize and react against the LPS present in infecting bacteria. In P. acnes-primed mice null for LPS-binding protein (LBP(-/-) mice), the impaired LPS recognition, due to the absence of LBP, resulted in a higher resistance to serovar Typhimurium infection. A similar P. acnes priming of mice had a protective, but no deleterious effect on a subsequent L. monocytogenes infection. This effect was IFN-gamma dependent but independent of LBP.

Kupffer cell-mediated recruitment of dendritic cells to the liver crucial for a host defense

Tissue recruitment of dendritic cells (DCs) is essential for antigen presentation. When latex particulates were injected intravenously into rats, DC precursors were recruited to the liver. Propionibacterium acnes also induced the recruitment of definite mouse DC precursors. These DCs initially showed a selective binding to Kupffer cells. In the Kupffer cell-depleted rats, DCs could neither be recruited to the liver nor adhere to sinusoidal walls. Pretreatment with varied monosaccharides in vitro showed that sugar residues consisting of N-acetylgalactosamine were necessary for this binding. Mouse DC precursors had CC-chemokine receptor 1 and 5, while granulama tissues and rat Kupffer cells expressed the corresponding chemokine, macrophage inflammatory protein-lalpha. Recruited DC precursors phagocytosed latex or bacteria and some of them soon translocated to hepatic nodes and induced the immune response there. We conclude that after invasion of pathogens, Kupffer cells not only scavenge them but also recruit DCs/DC precursors via chemokine- and N-acetylgalactosamine-mediated interactions. The accelerated DC traffic and the presence of blood-lymph translocation would induce rapid and efficient immune responses and thus contribute to the local defense to antigens within liver tissues as well as systemic defense to blood-borne antigens.

[Etiology of sarcoidosis]

The cause(s) of sarcoidosis is unknown. Sarcoidosis seems to result from exposure of a genetically susceptible subject to a specific environmental antigen(s). From biopsy samples of lymph nodes from patients with sarcoidosis, Propionibacterium acnes has been isolated in culture, and many genomes of P.acnes or P.granulosum have been detected by quantitative PCR. Antigen-specific mitogenic responses of peripheral blood mononuclear cells were induced in sarcoidosis patients but not in healthy controls, when recombinant proteins from a propionibacterial trigger factor were used as stimulators. Sarcoidosis may arise from a Th1 immune response to one or more antigens of propionibacteria in an individual with a hereditary or acquired abnormality of the immune system.

Distribution of rabies virus in infected mice, vaccinated and submitted to P. acnes as immunomodulator

The lethality and distribution of rabies virus were evaluated in swiss mice experimentally infected with street rabies virus, vaccinated and submitted to immunomodulation by P .acnes (formerly Corynebacterium parvum). The animals were sacrificed at different times,when the different tissues were collected and submitted to fluorescent antibody test (FAT) and mouse inoculation test (MIT). The group submitted to vaccination and P. acnes treatment presented a percentage of survival superior to that observed in infected mice only treated with P. acnes. Control infected animals had the lowest survival rates. The distribution of rabies virus in spleen of infected mice, vaccinated and submitted to P. acnes was superior to that verified in infected mice not treated with P.acnes. The increased survival correlated with the distribution of rabies virus in lymphoid tissues, could be interpreted as the consequence of P. acnes activity on macrophages. The results suggest the role of macrophages against rabies virus infection in mice and the importance of vaccination in the post expositive treatment of rabies.

Pivotal role of dendritic cell-derived CXCL10 in the retention of T helper cell 1 lymphocytes in secondary lymph nodes

Various immune diseases are considered to be regulated by the balance of T helper (Th)1 and Th2 subsets. Although Th lymphocytes are believed to be generated in draining lymph nodes (LNs), in vivo Th cell behaviors during Th1/Th2 polarization are largely unexplored. Using a murine granulomatous liver disease model induced by Propionibacterium acnes, we show that retention of Th1 cells in the LNs is controlled by a chemokine, CXCL10/interferon (IFN) inducible protein 10 produced by mature dendritic cells (DCs). Hepatic LN DCs preferentially produced CXCL10 to attract 5'-bromo-2'-deoxyuridine (BrdU)+CD4+ T cells and form clusters with IFN-gamma-producing CD4+ T cells by day 7 after antigen challenge. Blockade of CXCL10 dramatically altered the distribution of cluster-forming BrdU+CD4+ T cells. BrdU+CD4+ T cells in the hepatic LNs were selectively diminished while those in the circulation were significantly increased by treatment with anti-CXCL10 monoclonal antibody. This was accompanied by accelerated infiltration of memory T cells into the periphery of hepatic granuloma sites, most of them were in cell cycle and further produced higher amount of IFN-gamma leading to exacerbation of liver injury. Thus, mature DC-derived CXCL10 is pivotal to retain Th1 lymphocytes within T cell areas of draining LNs and optimize the Th1-mediated immune responses.

Expression and role of CD14 in mice sensitized to lipopolysaccharide by Propionibacterium acnes

Propionibacterium acnes-primed mice develop an IFN-gamma-dependent hypersensitivity towards LPS. Since CD14 plays a key role in LPS-induced cell activation the regulation and function of CD14 in this sensitization process were studied in IFN-gamma R-/- and the respective wild-type (wt) mice. In unprimed mice, CD14 (mRNA and protein) was either absent (liver) or only weakly expressed in organs (spleen, lung) and in plasma. Priming with P. acnes led to a moderate, mainly IFN-gamma-dependent up-regulation of CD14. LPS challenge of unprimed mice induced an IFN-gamma-independent increase in CD14 mRNA and CD14 protein. LPS challenge of P. acnes-primed mice induced a strong CD14 overexpression. This response was completely absent in IFN-gamma R-/- mice and is therefore strictly IFN-gamma-dependent. The requirement for CD14 in LPS hyper-responsiveness was assessed by comparing CD14-/- and the respective wt mice with respect to their ability to produce TNF and IFN-gamma, two recognized indices of LPS activity. LPS challenge without priming led to a weaker cytokine reaction in CD14-/- than in wt mice. However, priming with P. acnes enhanced the cytokine response to LPS in both wt and CD14-/- mice, although in the latter absolute levels of cytokines were lower. Therefore, hyperreactivity to LPS is characterized by an up-regulation of CD14, but the sensitization by P. acnes is not CD14 dependent.

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.

Cutting edge: Th2 response induction by dendritic cells: a role for CD40

We investigated the influence of dendritic cell (DC) CD40 expression on Th2 and Th1 development by in vivo transfer of Ag-pulsed bone marrow-derived DC generated from wild-type (WT) or CD40(-/-) mice. Contrary to expectation, CD40(-/-) DC primed with Ag that inherently induce a Th2 response (soluble egg Ag from Schistosoma mansoni) failed to induce a Th2 response or any compensatory Th1 response, whereas CD40(-/-)DC primed with Ag that inherently induce a Th1 response (Propionibacterium acnes) generated a competent Th1 response. Thus, DC expression of CD40 is a prerequisite for initiation of Th2, but not Th1, responses by these Ag. Consistent with this, CD154(-/-) mice, unlike WT mice, failed to mount a Th2 response when directly injected with schistosome eggs but mounted a normal Th1 response after challenge with P. acnes. CD40-CD154 interaction can therefore play a major role in Th2 response induction.

Sinusoidal endothelial cell injury by superoxide anion and iron in the Propionibacterium acnes-pretreated and lipopolysaccharide-stimulated rat liver

AIMS/BACKGROUND

We attempted to measure the generation of superoxide anion, examine its site of release and determine its pathological role in Propionibacterium acnes-lipopolysaccharide-induced liver injury in the rat.

METHODS

The P. acnes-pretreated (16 mg/kg i.v.) rat liver was perfused with buffer containing lipopolysaccharide (2.5 microg/ml). Chemiluminescence enhanced with Cypridina luciferin analog, MCLA, and reduction of nitro blue tetrazolium were used for detecting superoxide anion. Leakage of enzymes and release of cytokines into the perfusate, and histological specimens were also examined.

RESULTS

Superoxide dismutase-inhibitable chemiluminescence peaked at 30 min of lipopolysaccharide infusion and blue formazan precipitate was histochemically deposited mainly on hepatic macrophages. Purine nucleoside phosphorylase (PNP) activity in the perfusate, as a marker of sinusoidal endothelial cell injury, reached its maximum at 50 min and aspartate aminotransferase (AST) activity, as a marker of hepatocyte injury, reached a plateau at 90 min. Simultaneous treatment with superoxide dismutase and deferoxamine mesylate significantly suppressed the leakage of PNP and AST. Release of tumor necrosis factor-alpha and growth-related oncogene/cytokine-induced neutrophil chemoattractant-1 lagged behind PNP leakage. Light microscopy showed destruction of the sinusoids followed by hepatocyte necrosis. Electron microscopy revealed adherence of hepatic macrophages to sinusoidal endothelial cells.

CONCLUSION

These results indicate that superoxide anion released from hepatic macrophages may induce sinusoidal endothelial cell injury via interaction with iron in the P. acnes-lipopolysaccharide-treated liver.

Protein tyrosine nitration in mouse peritoneal macrophages activated in vitro and in vivo: evidence against an essential role of peroxynitrite

Tyrosine nitration is considered a key reaction of peroxynitrite-triggered tissue injury in inflammatory diseases. We investigated the potential involvement of peroxynitrite in protein tyrosine nitration in isolated murine peritoneal macrophages activated either in vitro with interferon-gamma/lipopolysaccharide or in vivo by priming mice with Corynebacterium parvum (10 mgxkg-1). Both protocols led to release of NO and accumulation of nitrite accompanied by formation of protein-bound 3-nitrotyrosine. Oxidation of dihydrorhodamine 123, a measure of peroxynitrite release, remained close to basal levels upon in vitro activation of the macrophages but was increased approximately twofold in vivo. Tyrosine nitration in macrophages activated in vitro was inhibited by catalase and the time course of nitration correlated with nitrite accumulation, whereas superoxide (O2*-) and H2O2 release occurred at much earlier times. To address the contribution of O2*- and peroxynitrite to in vivo nitration, a O2*- scavenger (MnTBAP; 1 mgxkg-1) was given to C. parvum-primed mice. MnTBAP led to almost complete inhibition of C. parvum-triggered O2*- and peroxynitrite release, whereas nitrite accumulation and formation of 3-nitrotyrosine were less affected ( approximately 50% of controls). These results argue against an essential role of peroxynitrite in protein tyrosine nitration in vivo.

[Mechanisms behind the development of antibiotic resistant bacteria]

BACKGROUND

Bacterial resistance to antibiotics is an increasing threat to the successful treatment of hospital and community-acquired infections.

MATERIAL AND METHODS

Based on relevant literature, this article focuses on some of the essential resistance problems caused by pathogens such as pneumococci, staphylocci, enterococci and gram-negative rods, and provides a review of the genetic and molecular basis of bacterial resistance, as well as of the global trends in bacterial resistance.

RESULTS

Mechanisms of resistance continue to evolve and disseminate among gram-negative as well as gram-positive pathogens. New problems are developing, such as glycopeptide resistance in Staphylococcus aureus. Bacteria have become resistant to antibiotics as a result of chromosomal changes or the exchange of genetic material via plasmids and transposons. The emergence of multiresistant bacteria e.g. S. aureus, enterococci and Mycobacterium tuberculosis, has made many currently available antibiotics ineffective.

INTERPRETATION

The introduction of new antibiotics has always been followed by development of resistance.

CD8- dendritic cell activation status plays an integral role in influencing Th2 response development

Whether dendritic cells (DC) play a passive or active role in Th2 response induction is poorly understood. In this study, we show that CD8- DC pulsed with Th2-polarizing Ag (soluble egg Ag (SEA)) from Schistosoma mansoni potently stimulate Th2 responses in vivo and in vitro while failing to undergo a conventional maturation process. Thus, in contrast to DC pulsed with the Th1 response inducing Ag Propionebacterium acnes, SEA-exposed DC exhibit a phenotype that is most similar to that of immature DC, failing to up-regulate expression of CD40, CD54, CD80, CD86, or OX40L; producing no detectable IL-4, IL-10, or IL-12; and displaying only a minor increase in MHC class II expression. Importantly, in vitro derived DC exposed to SEA were phenotypically similar to CD8- DC isolated from active S. mansoni infection. By discriminating between different types of pathogen and responding appropriately, CD8- DC play a major role in the decision process to mount either a Th1 or Th2 response.

Role of monocyte chemoattractant protein-1 in Propionibacterium acnes-induced pulmonary granulomatosis

The inflammatory process in granulomatous disorders such as sarcoidosis is mainly the consequence of delayed hypersensitivity induced by causative antigens. Propionibacterial DNA was isolated recently by PCR from human sarcoidosis tissue. Hence, we developed a model using sensitized rabbits for T cell-mediated pulmonary granulomatosis induced by Propionibacterium acnes (P. acnes) and investigated the role of monocyte chemoattractant protein-1 (MCP-1) in the pathogenesis of the granuloma formation in vivo. Intravenous injection of P. acnes into sensitized rabbits induced massive pulmonary granulomas on day 3. Maximum levels of MCP-1 in sera and bronchoalveolar lavage fluid (BALF) were detected on day 1 and preceded recruitment of monocyte/macrophages and T cells. In BALF, monocyte chemotaxis peaked 1 day after P. acnes challenge, and T cell chemotaxis peaked 3 days after P. acnes challenge. Anti-MCP-1 IgG inhibited monocyte chemotaxis by 80.2% and T cell chemotaxis by 35.7%. Phenotypic analysis of migrating T cells revealed that activated and memory T cells (CD26(+)/CD45RO(+)) but not naive cells were preferentially attracted to BALF. Administration of MCP-1 antiserum in vivo inhibited the development of granulomas in both size 59.9% reduction and number 28.6% reduction, the number of infiltrating leukocytes in BALF, and the expression of adhesion molecules on leukocytes in peripheral blood and BALF. Our data indicate that MCP-1 plays important roles in granuloma formation by attracting and activating specific types of cells in this model. Furthermore, results suggest that the rabbit model resembles human angiocentric granulomatosis and would be useful for investigating the immunopathogenesis of human pulmonary granulomatosis.

Equipotent generation of protective antitumor immunity by various methods of dendritic cell loading with whole cell tumor antigens

Multiple clinically applicable methods have been used to induce dendritic cells (DCs) to express whole cell tumor antigens, including pulsing DCs with tumor lysate, and mixing DCs with apoptotic or live tumor cells. Herein we demonstrate, using two different tumor systems, that these methods are equipotent inducers of systemic antitumor immunity. Furthermore, tumor lysate pulsed DC vaccines generate more potent antitumor immunity than immunization with irradiated tumor cells plus the classic adjuvant, Corynebacterium parvum.

Antigen-specific T(h)1 cells as direct effectors of Propionibacterium acnes-primed lipopolysaccharide-induced hepatic injury

T(h)1 cells are cytotoxic effector cells that utilize Fas ligand (FasL) and tumor necrosis factor. The physiological roles of cytotoxic T(h)1 cells are considered to be immunoregulation by eliminating autoreactive lymphocytes or hyper-activated foreign antigen-specific lymphocytes. Their pathological roles, however, remain to be clarified. To investigate whether T(h)1 cells can destroy organs, we generated a Propionibacterium acnes-specific T(h)1 clone from C57BL/6 mice and tested whether the clone could serve as an effector in a P. acnes-primed lipopolysaccharide (LPS)-induced hepatic injury system, one of the septic shock models. B6SMN:C3H-FasL(gld) (B6-gld) mice, which were deficient in functional FasL, were resistant to P. acnes/LPS-induced hepatic shock. The T(h)1 clone rendered B6-gld mice sensitive to the hepatic shock after the i.v. transfer. The hepatic injury in the clone-transferred B6-gld mice, which was evaluated by both biochemical and histological examination, was inhibited by an anti-FasL mAb that we developed. These results suggested that bacterial antigen-specific T(h)1 cells like this clone can participate in organ destruction in vivo as one of the cytotoxic effectors and play a critical role in endotoxin-induced hepatic injury.

Cytokine expression in the mouse brain in response to immune activation by Corynebacterium parvum

Cytokine expression in the brain has been suggested to mediate various sickness behaviors. Here we report that intraperitoneal injection of a Corynebacterium parvum antigen in C57BL/6 mice was followed by prolonged upregulation of cytokines in the cerebral cortex and subcortical structures in a time course that coincided with reduced spontaneous running activity.

Blockade of secondary lymphoid tissue chemokine exacerbates Propionibacterium acnes-induced acute lung inflammation

Chemokine-chemokine receptor interaction plays an essential role in leukocyte/dendritic cell (DC) trafficking in inflammation and immune responses. We investigated the pathophysiological roles of secondary lymphoid tissue chemokine (SLC; CCL21) and macrophage inflammatory protein-2 (MIP-2) in the development of acute pulmonary inflammation induced by an intratracheal injection of Propionibacterium acnes in mice. Immunohistochemical studies revealed that SLC was constitutively expressed in the peribronchial areas and perivascular lymphatics in normal mice. MIP-2-positive cells were observed in alveolar spaces in mice challenged with P. acnes. Both neutralization Abs against MIP-2 and CXC chemokine receptor 2 alleviated the P. acnes-induced pulmonary inflammation when injected before P. acnes Ag challenge. On the other hand, polyclonal anti-SLC Abs (pAbs) exacerbated the pulmonary inflammation. The numbers of mature DCs (MHC class II +, CD11c+, and CD86+) as well as macrophages and neutrophils in the P. acnes Ag-challenged lungs were increased, whereas the number of CD4+ T cells, including memory T cells, was decreased. The numbers of mature and proliferating CD4+ T cells (bromodeoxyuridine(+)CD4+) in regional lymph nodes were decreased in mice injected with anti-SLC pAbs compared with those in mice treated with control Abs. An in vitro proliferation assay confirmed the impairment of the Ag-specific T cell response in regional lymph nodes of mice treated with anti-SLC pAbs. These results indicate for the first time a regulatory role for SLC-recruited mature DCs in bridging an acute inflammatory response (innate immunity) and acquired immunity in the lung.

Inherited IL-12 unresponsiveness contributes to the high LPS resistance of the Lps(d) C57BL/10ScCr mouse

LPS(d) mouse strains are characterized by the presence of a defective LPS/tlr4 gene that make them refractory to the biological activity of LPS. One of the mouse strains commonly used to study LPS defects is the C57BL/10ScCr (Cr) strain. However, unlike other LPS(d) strains, the Cr strain also has a heavily impaired IFN-gamma response to micro-organisms. As a consequence, unlike other LPS(d) mouse strains, they do not acquire a partial LPS susceptibility when treated with sensitizing bacteria. Because IL-12 is important for the microbial induction of IFN-gamma, we investigated whether the production or function of IL-12 might be defective in Cr mice. IL-12 mRNA (p35 and p40) was present in the spleen of untreated Cr mice, IL-12p40 mRNA was inducible in mice injected with live or killed Salmonella typhimurium, and IL-12 (p70) was inducible in macrophages by bacteria. Thus, Cr mice exhibit normal IL-12 responses. In functional tests, splenocytes of untreated or of S. typhimurium-infected mice failed to produce IFN-gamma when stimulated with murine rIL-12 or with a combination of IL-12 and murine rIL-18 or Con A. Furthermore, Cr mice were identical with IL-12p35/p40 and IL-12 receptor beta(1) knockout mice in their impaired in vivo and in vitro IFN-gamma responses to bacteria. Thus, Cr mice carry a second genetic defect unrelated to the Lps/tlr4 mutation that underlies the IL-12 unresponsiveness and contributes to the LPS resistance and impaired innate immune response in this strain.

Inflammatory acne represents hypersensitivity to Propionibacterium acnes

Hypersensitivity to P. acnes may account for the great variation in acne severity. Alternative explanations such as hyperandrogenism fail to account for disease severity in large numbers of patients.

Preventive effect of FK 506 (tacrolimus hydrate) on experimentally induced acute liver injury in rats

The aim of the study was to investigate the effect of the immunosuppressant FK 506 (tacrolimus hydrate) on acute liver injury induced by Propionibacterium acnes and lipopolysaccharide (LPS). Acute liver injury was induced in male Wistar rats by injecting the animals with P. acnes (10 mg/rat), and administering LPS (10 microg/rat) seven days later. One group was given FK 506 (1 mg/kg) 24 and 2 hr before administration of LPS, and the other group was given the same dose of saline. The 24-hr survival rate, serum alanine aminotransferase (ALT) concentration, and tumor necrosis factor (TNF) -alpha mRNA and protein concentrations in the liver and spleen were then compared. Hepatic macrophages were also isolated from rats seven days after P. acnes injection, LPS, and FK 506 or saline were added to the culture supernatant, and TNF-alpha production was studied. The 24-hr survival rate was 100% in the FK 506-treated group, in contrast with 16.6% in the saline group. Four hours after LPS injection, the serum ALT concentration was 755 +/- 401 in the saline group versus 119 +/- 42 units/ml (P < 0.01) in the FK 506-treated group. The serum TNF-alpha concentration was lower in the FK 506-treated group (1,419 +/- 957 pg/ml) than in the saline group (9205 +/- 2215) (P < 0.01). The mRNA and protein concentrations in the liver and spleen in the two groups did not differ significantly 1 hr after LPS injection but were significantly lower in the FK 506-treated group after 4 hr. FK 506 did not directly inhibit TNF-alpha production by isolated cultured hepatic macrophages. FK 506 is unable to inhibit initial TNF-alpha production by hepatic macrophages (or probably that by splenic macrophages either) stimulated by injection of LPS in P. acnes + LPS-induced acute liver injury. However, the immunosuppressant does limit hepatic damage by inhibiting subsequent aggravation of inflammation by the cytokine network.