transforming-growth-factor-beta and Bacteroides-Infections

Growth factors such as keratinocyte growth factor-2 (KGF-2) and transforming growth factor-beta (TGF-β) are important immunoregulatory and epithelial growth factors. They are also potential therapeutic proteins for inflammatory bowel disease. However, owing to protein instability in the upper gastrointestinal tract, it is difficult to achieve therapeutic levels of these proteins in the injured colon when given orally. Furthermore, the short half-life necessitates repeated dosage with large amounts of the growth factor, which may have dangerous side effects, hence the importance of temporal and spatial control of growth factor delivery.. The human commensal gut bacterium, Bacteroides ovatus, was genetically engineered to produce human KGF-2 or TGF-β1 (BO-KGF or BO-TGF) in a regulated manner in response to the dietary polysaccharide, xylan. The successful application of BO-KGF or BO-TGF in the prevention of dextran sodium sulphate induced murine colitis is presented here.. This novel drug delivery system had a significant prophylactic effect, limiting the development of intestinal inflammation both clinically and histopathologically. The ability to regulate heterologous protein production by B ovatus using xylan is both unique and an important safety feature of this drug delivery system.. The use of genetically engineered B ovatus for the controlled and localised delivery of epithelial growth promoting and immunomodulatory proteins has potential clinical applications for the treatment of various diseases targeting the colon.

Topics: Animals; Anti-Inflammatory Agents; Bacteroides; Bacteroides Infections; Colitis; Dextran Sulfate; Drug Delivery Systems; Fibroblast Growth Factor 10; Genetic Engineering; Irritants; Male; Mice; Mice, Inbred C57BL; Probiotics; Transforming Growth Factor beta; Xylans

A retrospective clinical study.. To evaluate the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) as the primary graft material for the surgical treatment of vertebral osteomyelitis.. The clinical and radiographic results using allograft, autograft, and vascularized bone flaps for the surgical treatment of osteomyelitis have been previously reported. Despite an expanding body of literature documenting the value of rhBMP-2 in spinal fusion, its application to the management of spinal infection has never before been analyzed.. Twenty patients underwent surgical treatment of vertebral osteomyelitis using rhBMP-2 and were analyzed with a mean follow-up of 40 months (range, 24-53 months). All patients were treated with anterior column debridement and instrumented reconstruction. Four (20%) patients were treated with an anterior approach alone while the remaining 16 (80%) patients underwent circumferential spinal reconstruction. Clinical outcomes were assessed by Frankel grade and Odom criteria. Radiographic fusion was characterized based on thin-section computerized tomography (CT) analysis.. Pathogens responsible for infection included Staphylococcus aureus (11; 55%), S. epidermidis (6; 30%), Bacteroides (1; 5%), and polymicrobial species (1; 5%). Infected segments of the spinal column based on region were found to be: thoracic (1; 5%), thoracolumbar (5; 25%), lumbar (11; 55%), and lumbosacral (3; 15%). The mean number of anterior and posterior segments fused was 3.3 (range, 2-5) and 6.5 (range 2-16), respectively. Forty-five percent of the subjects underwent multilevel corpectomies and fusion. All patients demonstrated clinical and radiographic evidence of spinal fusion at the time of follow-up. Patients had stable (14 patients) or improved (6 patients) Frankel grades after surgery. Odom criteria at final follow-up were: excellent (3; 15%), good (12; 60%), fair (4; 20%), and poor (1; 5%). There was no case of persistent or recurrent infection requiring revision surgery.. rhBMP-2 is a valuable graft option for the surgical treatment of vertebral osteomyelitis. When dosed in the manner reported, very high rates of fusion are achievable as is eradication of infection.

Topics: Adult; Aged; Anti-Bacterial Agents; Bacteroides; Bacteroides Infections; Bone Morphogenetic Protein 2; Bone Morphogenetic Proteins; Bone Transplantation; Combined Modality Therapy; Debridement; Female; Humans; Intraoperative Complications; Magnetic Resonance Imaging; Male; Middle Aged; Osteomyelitis; Recombinant Proteins; Retrospective Studies; Spinal Diseases; Spinal Fusion; Staphylococcal Infections; Staphylococcus aureus; Staphylococcus epidermidis; Transforming Growth Factor beta; Treatment Outcome

We have shown that non-pathogenic enteric Gram-negative Bacteroides vulgatus induces RelA phosphorylation, NF-kappaB activation, and proinflammatory gene expression in primary and intestinal epithelial cell (IEC) lines. We now demonstrate the transient induction of nuclear phospho-RelA (day 3) followed by persistent activation of phospho-Smad2 (days 3 and 7) in IEC from mucosal tissue sections of B. vulgatus-monoassociated rats, indicating that both NF-kappaB and transforming growth factor-beta1 (TGF-beta1) signaling are induced in vivo following bacterial colonization. Interestingly, TGF-beta1 inhibited B. vulgatus- and lipopolysaccharide (LPS)-induced NF-kappaB transcriptional activity as well as interleukin-6 (IL-6) mRNA accumulation and protein secretion in IEC. The inhibitory effect of TGF-beta1 is mediated independently of B. vulgatus/LPS-induced IkappaBalpha, Akt, and RelA phosphorylation as well as NF-kappaB DNA binding activity. Moreover, the specific histone deacetylase inhibitor trichostatin A blocked B. vulgatus/LPS-induced histone acetylation/phosphorylation (Lys-9/Ser-10) and reversed TGF-beta1-mediated inhibition of IL-6 gene expression. Chromatin immunoprecipitation analysis revealed that B. vulgatus/LPS-induced RelA recruitment to the IL-6 promoter is inhibited by TGF-beta1 treatment. Adenoviral delivery of Smad7 and dominant negative Smad3 (SmadDelta3) reversed the TGF-beta1-mediated inhibition of NF-kappaB transcriptional activity and NF-kappaB recruitment to the IL-6 promoter. In addition, TGF-beta1 and Ad5Smad3/4 prevent B. vulgatus/LPS-induced CBP/p300 and p65 nuclear co-association. We concluded that the TGF-beta1/Smad signaling pathway helps maintain normal intestinal homeostasis to commensal luminal enteric bacteria by regulating NF-kappaB signaling in IEC through altered histone acetylation.

Topics: Acetylation; Animals; Bacteroides; Bacteroides Infections; Cell Line; Gram-Negative Bacteria; Histones; Interleukin-6; Intestinal Mucosa; Lipopolysaccharides; Mice; NF-kappa B; Promoter Regions, Genetic; Rats; Rats, Inbred F344; Signal Transduction; Transcription, Genetic; Transforming Growth Factor beta; Transforming Growth Factor beta1

Sepsis is associated with depressed T-cell functions and increased circulating levels of immunosuppressive agents. TGF-beta is a potential anti-inflammatory cytokine that can modify T-cell growth and differentiation. The up-regulation of TGF-beta and the mechanism of its action on the T-cells during septic injury have not been resolved. We hypothesized that in sepsis TGF-beta produced by macrophages acts on T-cells in a paracrine manner to suppress interleukin (IL)-2 production and proliferation. In this study, we examined the circulating TGF-beta levels in a rat model of Gram-negative bacterial sepsis, and compared the abilities of adherent and non-adherent splenocytes to produce TGF-beta. Additionally, we investigated the causal relationships of hrTGF-beta to concanavalin A (ConA)-induced T-cell responses and the intracellular mechanism of the generation of these responses in normal splenic rat T-cells. Sepsis was induced in rats by intraabdominally implanting fecal pellets containing Escherichia coli (150 CFU) and Bacteroides fragilis (10000 CFU). Adherent and non-adherent splenocytes were isolated by differential adherence using Ficoll gradient centrifugation. T-cells were purified by use of Nylon wool columns. We observed a 3-6-fold increase in the circulating levels of TGF-beta in sepsis. Western blots and ELISA determinations revealed a 2.5-3-fold increase in cell-associated TGF-beta protein levels in adherent splenic cells. Northern analyses also showed a marked increase in TGF-beta mRNA expression in adherent cells during sepsis. On the other hand, a significant change was not observed in the TGF-beta protein and mRNA expression in non-adherent splenocytes. Pretreatment of control rat T-cells with hrTGF-beta decreased both ConA-induced proliferation (by 35-40%) and IL-2 mRNA expression (by > 50%). Further, whereas incubation of control rat T-cells with either ConA or TGF-beta for 24 h resulted in a 10-15-fold increase in cAMP generation, the addition of hrTGF-beta along with ConA resulted in a 50-60-fold increase in cAMP. These results suggest that in sepsis, TGF-beta produced by splenic macrophages can act in a paracrine manner on T-cells to depress their IL-2 mRNA expression, IL-2 production and proliferation after up-regulation of cAMP which can interfere with T-cell signaling for proliferation.

Topics: Animals; Bacteremia; Bacteroides fragilis; Bacteroides Infections; Cell Adhesion; Concanavalin A; Cyclic AMP; Enzyme-Linked Immunosorbent Assay; Escherichia coli Infections; Interleukin-2; Lymphocyte Activation; Male; Rats; Rats, Sprague-Dawley; Reference Values; Spleen; T-Lymphocytes; Transcription, Genetic; Transforming Growth Factor beta