transforming-growth-factor-beta and Gram-Positive-Bacterial-Infections

Fulminant hepatic failure (FHF) is a clinical syndrome characterized by sudden and severe impairment of liver function. Mesenchymal stem cells (MSCs) have been proposed as a promising therapeutic approach for FHF. In this study we used Propionibacterium acnes (P. acnes)-primed, lipopolysaccharide (LPS)-induced liver injury in mice as an animal model of human FHF. We demonstrated that administration of MSCs significantly ameliorated liver injury and improved the survival rates of mice subjected to P. acnes plus LPS-induced FHF. Allogeneic MSCs showed similar treatment efficacy as autologous MSCs did in FHF. Treatment efficacy of MSCs could be attributed to decreased infiltration and activation of CD4(+) T cells in the liver, inhibition of T helper 1 cells, and induction of regulatory T cells (Tregs). Moreover, decreased DNA copies of P. acnes were detected in the liver of MSC-treated mice. Intriguingly, a distinct liver population of CD11c(+) MHCII(hi) CD80(lo) CD86(lo) regulatory dendritic cells (DCs) was induced by MSCs. Moreover, these DCs induced Treg differentiation through transforming growth factor-β production. Further mechanistic studies demonstrated that MSC-derived prostaglandin E2 and one of its receptors, EP4, played essential roles in the differentiation of CD11c(+) B220(-) DC precursors into regulatory DCs in a phosphoinositide 3-kinase-dependent manner.. MSCs induce regulatory DCs from CD11c(+) B220(-) DC precursors. This study elucidates an immunoregulatory mechanism of MSCs and lays a foundation for application of MSCs in FHF therapy.

Topics: Animals; Cell- and Tissue-Based Therapy; Dendritic Cells; Disease Models, Animal; Gram-Positive Bacterial Infections; Lipopolysaccharides; Liver; Liver Failure, Acute; Mesenchymal Stem Cell Transplantation; Mesenchymal Stem Cells; Mice; Mice, Inbred C57BL; Propionibacterium acnes; Receptors, Prostaglandin E, EP4 Subtype; Signal Transduction; T-Lymphocytes, Regulatory; Th1 Cells; Transforming Growth Factor beta

To examine cytokine expression profiles during periapical lesion development in response to synergetic human pathogens in a gnotobiotic mouse model.. Human strains of Fusobacterium nucleatum and Peptostreptococcus prevotii were inoculated into the root canals of germ-free mice in either mono- or bi-association. Animals were killed 7 and 14 days after infection, and periapical tissues were collected. mRNA expression of the cytokines IFN-γ, TNF-α, Receptor activator of nuclear factor kappa-B ligand (RANKL), IL-10, IL-4 and transforming growth factor β (TGF-β) was assessed using real-time PCR. Levene's test was used to assess the equality of variance of the data, whereas a t-test for independent samples was used to evaluate the significance of the differences between groups (P < 0.05).. The mRNA expression of IFN-γ and TNF-α was up-regulated by F. nucleatum during the acute (day 7) and chronic phase (day 14) of periapical lesion development. However, in bi-infection the expression of IFN-γ and TNF-α were effectively absent at both time-points. RANKL mRNA expression was down-regulated during dual infection at the chronic phase. As IL-4 expression was similar at both time-points, IL-4 does not appear to be involved in the periapical response to these bacterial strains. IL-10 was up-regulated during the chronic phase by mono-infection with either F. nucleatum or P. prevotii. Dual infection increased TGF-β mRNA expression on day 7, which paralleled the decrease in IFN-γ and TNF-α mRNA levels at the same time-point. F. nucleatum increased TGF-β mRNA expression during the chronic phase.. Cytokine profiles depend on the nature of the bacterial challenge. Both TGF-β and IL-10 appeared to be regulating the proinflammatory cytokine responses at both time-points of the periapical immune response.

Topics: Animals; Coinfection; Cytokines; Dental Pulp Diseases; Fusobacterium Infections; Fusobacterium nucleatum; Germ-Free Life; Gram-Positive Bacterial Infections; Humans; Inflammation Mediators; Interferon-gamma; Interleukin-10; Interleukin-4; Mice; Peptostreptococcus; Periapical Diseases; RANK Ligand; Real-Time Polymerase Chain Reaction; RNA, Messenger; Time Factors; Transforming Growth Factor beta; Up-Regulation

Nonpathogenic enteric bacterial species initiate and perpetuate experimental colitis in IL-10 gene-deficient mice (IL-10(-/-)). Bacteria-specific effects on the epithelium are difficult to dissect due to the complex nature of the gut microflora. We showed that IL-10(-/-) mice compared with wild-type mice fail to inhibit proinflammatory gene expression in native intestinal epithelial cells (IEC) after the colonization with colitogenic Gram-positive Enterococcus faecalis. Interestingly, proinflammatory gene expression was transient after 1 wk of E. faecalis monoassociation in IEC from wild-type mice, but persisted after 14 wk of bacterial colonization in IL-10(-/-) mice. Accordingly, wild-type IEC expressed phosphorylated NF-kappaB subunit RelA (p65) and phosphorylated Smad2 only at day 7 after bacterial colonization, whereas E. faecalis-monoassociated IL-10(-/-) mice triggered persistent RelA, but no Smad2 phosphorylation in IEC at days 3, 7, 14, and 28. Consistent with the induction of TLR2-mediated RelA phosphorylation and proinflammatory gene expression in E. faecalis-stimulated cell lines, TLR2 protein expression was absent after day 7 from E. faecalis-monoassociated wild-type mice, but persisted in IL-10(-/-) IEC. Of note, TGF-beta1-activated Smad signaling was associated with the loss of TLR2 protein expression and the inhibition of NF-kappaB-dependent gene expression in IEC lines. In conclusion, E. faecalis-monoassociated IL-10(-/-), but not wild-type mice lack protective TGF-beta/Smad signaling and fail to inhibit TLR2-mediated proinflammatory gene expression in the intestinal epithelium, suggesting a critical role for IL-10 and TGF-beta in maintaining normal epithelial cell homeostasis in the interplay with commensal enteric bacteria.

Topics: Animals; Cell Line; Cells, Cultured; Colitis; DNA-Binding Proteins; Enterococcus faecalis; Gene Expression Regulation; Gram-Positive Bacterial Infections; Inflammation Mediators; Interleukin-10; Intestinal Mucosa; Mice; Mice, Inbred C3H; Mice, Knockout; NF-kappa B; Phosphorylation; Receptors, Cell Surface; Signal Transduction; Smad Proteins; Toll-Like Receptor 2; Trans-Activators; Transcription Factor RelA; Transforming Growth Factor beta; Transforming Growth Factor beta1

The aim of the present study was to evaluate the potential prognostic value of MIP-1 alpha, TGF-beta 2, sELAM-1, and sVCAM-1 in patients with gram-positive sepsis. Twenty-eight patients with gram-positive sepsis were compared to 11 patients with gram-negative sepsis and 15 healthy volunteers. Sepsis was defined by the criteria of Bone et al. (Crit. Care Med. 21, 5447-5463, 1993) and by isolation of at least two positive blood cultures with gram-positive/gram-negative bacteria. Plasma samples for determination of the immunological parameters were collected daily. Analysis of cytokines and adhesion molecules was performed on days 0 (day of sepsis criteria fulfillment), 4, and 7 (or 1 day before death). In the gram-positive group 10 of 28 patients died; in the gram-negative group 4 of 11 died. Only sELAM-1 plasma concentrations were found to be a useful early parameter in predicting patients' outcome in gram-positive sepsis. sELAM-1 concentrations at the onset of the study (day 0) were significantly higher in the nonsurviving patients than those in the survivors. MIP-1 alpha levels were significantly higher only on days 4 and 7. With regard to the measured plasma concentrations we believe that MIP-1 alpha is not a useful parameter for predicting patients' prognosis. The increase of sVCAM-1 might play a role in the pathogenesis of gram-positive sepsis; however, it could not be relied upon as an early prognostic parameter. The potential role of TGF-beta 2 in the development of gram-positive sepsis could not evaluated in the present study, whereas routine measurements of TGF-beta 2 offered no additional prognostic information.

Topics: Adult; Aged; Aged, 80 and over; Chemokine CCL4; E-Selectin; Female; Gram-Positive Bacterial Infections; Humans; Macrophage Inflammatory Proteins; Male; Middle Aged; Prognosis; Sensitivity and Specificity; Sepsis; Transforming Growth Factor beta; Vascular Cell Adhesion Molecule-1

In view of its potent inhibitory capacity on immune cells in culture, we wished to determine the ability of transforming growth factor (TGF) beta 1 to down-regulate immune responses in vivo. Preliminary experiments suggested that, at the doses used, systemic injection of soluble TGF beta 1 could not affect bacterial-induced spleen enlargement in mice. Therefore, we sought to utilize a physiochemical property of this molecule, namely its high pI, to determine possible association between the ligand and preformed liposomes possessing an opposite charge. TGF beta 1 was preferentially associated with negatively charged, but not with neutral, liposomes. These TGF beta 1 associated liposomes were able to deliver a suppressive signal to indicator cells in vitro. Intravenous injection of TGF beta 1, associated with liposomes possessing an opposite charge, into mice immunized with heat-killed Corynebacterium parvum significantly reduced the size of the spleen as well as the number of splenocytes. Systemically administered TGF beta 1 associated liposomes could also inhibit delayed type hypersensitivity reactions to Listeria monocytogenes. These data suggest that appropriately administered, TGF beta 1 can inhibit immune responses in vivo.

Topics: Analysis of Variance; Animals; Dose-Response Relationship, Immunologic; Down-Regulation; Female; Gram-Positive Bacterial Infections; Hypersensitivity, Delayed; Immunosuppression Therapy; Injections, Intravenous; Liposomes; Listeriosis; Mice; Mice, Inbred C57BL; Organ Size; Propionibacterium acnes; Spleen; Splenomegaly; Transforming Growth Factor beta