Follistatin-based ligand trap ACE-083 induces localized hypertrophy of skeletal muscle with functional improvement in models of neuromuscular disease.

Skeletal muscle is under inhibitory homeostatic regulation by multiple ligands of the transforming growth factor-ß (TGFß) superfamily. Follistatin is a secreted protein that promotes muscle growth and function by sequestering these ligands extracellularly. In the present study, we evaluated the potential of ACE-083 - a locally acting, follistatin-based fusion protein - as a novel therapeutic agent for focal or asymmetric myopathies. Characterization of ACE-083 in vitro revealed its high affinity for heparin and extracellular matrix while surface plasmon resonance and cell-based assays confirmed that ACE-083 binds and potently neutralizes myostatin, activin A, activin B and growth differentiation factor 11 (GDF11). Intramuscular administration of ACE-083 caused localized, dose-dependent hypertrophy of the injected muscle in wild-type mice and mouse models of Charcot-Marie-Tooth disease (CMT) and Duchenne muscular dystrophy, with no evidence of systemic muscle effects or endocrine perturbation. Importantly, ACE-083 also increased the force of isometric contraction in situ by the injected tibialis anterior muscle in wild-type mice and disease models and increased ankle dorsiflexion torque in CMT mice. Our results demonstrate the potential of ACE-083 as a therapeutic agent for patients with CMT, muscular dystrophy and other disorders with focal or asymmetric muscle atrophy or weakness.

Helicobacter pylori infection stimulates plasminogen activator inhibitor 1 production by gastric epithelial cells.

Chronic infection with the gastric pathogen Helicobacter pylori significantly increases the risk of developing atrophic gastritis, peptic ulcer disease, and gastric adenocarcinoma. H. pylori strains that possess the cag pathogenicity island, which translocates CagA into the host cells, augment these risks. The aim of this study was to determine the molecular mechanisms through which H. pylori upregulates the expression of plasminogen activator inhibitor 1 (PAI-1), a member of the urokinase activator system that is involved in tumor metastasis and angiogenesis. Levels of PAI-1 mRNA and protein were examined in tissues from H. pylori-infected patients and in vitro using AGS gastric epithelial cells. In vitro, cells were infected with toxigenic cag-positive or nontoxigenic cag-negative strains of H. pylori or isogenic mutants. The amount of PAI-1 secretion was measured by enzyme-linked immunosorbent assay, and mRNA levels were determined using real-time PCR. The regulation of PAI-1 was examined using the extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor and small interfering RNA. Analysis of human biopsy samples revealed an increase in both PAI-1 mRNA and protein levels in patients with H. pylori gastritis compared to those of uninfected controls. Infection of AGS cells with H. pylori significantly increased PAI-1 mRNA expression and the secretion of PAI-1 protein. Moreover, PAI-1 mRNA and protein production was more pronounced when AGS cells were infected by H. pylori strains carrying a functional cag secretion system than when cells were infected by strains lacking this system. PAI-1 secretion was also reduced when cells were infected with either cagE-negative or cagA-negative mutants. The ectopic overexpression of CagA significantly increased the levels of PAI-1 mRNA and protein, whereas blockade of the ERK1/2 pathway inhibited H. pylori-mediated PAI-1 upregulation. These findings suggest that the upregulation of PAI-1 in H. pylori-infected gastric epithelial cells may contribute to the carcinogenic process.

p38 MAP kinase activation by Clostridium difficile toxin A mediates monocyte necrosis, IL-8 production, and enteritis.

Clostridium difficile toxin A causes acute neutrophil infiltration and intestinal mucosal injury. In cultured cells, toxin A inactivates Rho proteins by monoglucosylation. In monocytes, toxin A induces IL-8 production and necrosis by unknown mechanisms. We investigated the role of mitogen-activated protein (MAP) kinases in these events. In THP-1 monocytic cells, toxin A activated the 3 main MAP kinase cascades within 1 to 2 minutes. Activation of p38 was sustained, whereas stimulation of extracellular signal-regulated kinases and c-Jun NH(2)-terminal kinase was transient. Rho glucosylation became evident after 15 minutes. IL-8 gene expression was reduced by 70% by the MEK inhibitor PD98059 and abrogated by the p38 inhibitor SB203580 or by overexpression of dominant-negative mutants of the p38-activating kinases MKK3 and MKK6. SB203580 also blocked monocyte necrosis and IL-1beta release caused by toxin A but not by other toxins. Finally, in mouse ileum, SB203580 prevented toxin A-induced neutrophil recruitment by 92% and villous destruction by 90%. Thus, in monocytes exposed to toxin A, MAP kinase activation appears to precede Rho glucosylation and is required for IL-8 transcription and cell necrosis. p38 MAP kinase also mediates intestinal inflammation and mucosal damage induced by toxin A.

L-Ascorbic acid and L-galactose are sources for oxalic acid and calcium oxalate in Pistia stratiotes.

Axenic Pistia stratiotes L. plants were pulse-chase labeled with [14C]oxalic acid, L[1-14C]ascorbic acid, L-6-14C]ascorbic acid, D-[1-14C]erythorbic acid, L-[1-14C]galactose, or [1-14C]glycolate. Specific radioactivities of L-ascorbic acid (AsA), free oxalic acid (OxA) and calcium oxalate (CaOx) in labeled plants were compared. Samples of leaf tissue were fixed for microautoradiography and examined by confocal microscopy. Results demonstrate a biosynthetic role for AsA as precursor of OxA and its crystalline deposition product, CaOx, in idioblast cells of P. stratiotes and support the recent discovery of Wheeler, Jones and Smirnoff (Wheeler, G.L., Jones M.A., & Smirnoff, N. (1998). The biosynthetic pathway of vitamin C in higher plants. Nature, 393, 365-369) that L-galactose is a key intermediate in the conversion of D-glucose to AsA in plants. D-[1-14C]erythorbic acid (a diastereomeric analog of AsA) is utilized also by P. stratiotes as a precursor of OxA and its calcium salt deposition product in idioblasts. Labeled OxA is rapidly incorporated into CaOx in idioblasts, but microautoradiography shows there is also significant incorporation of carbon from OxA into other components of growing cells, contrary to the dogma that OxA is a relatively stable end product of metabolism. Glycolate is a poor substrate for synthesis of OxA and CaOx formation, further establishing AsA as th immediate precursor in the synthesis of OxA used for calcium precipitation in crystal idioblasts.

5-O-(alpha-D-galactopyranosyl)-D-glycero-pent-2-enono-1,4-lactone: characterization in the oxalate-producing fungus, Sclerotinia sclerotiorum.

Extracts of sclerotia from Sclerotinia sclerotiorum, a fungal phytopathogen, contain two electrochemically-active constituents, D-glycero-pent-2-enono-1,4-lactone (trivial name: D-erythroascorbic acid), and a previously unidentified compound, here characterized as 5-O-(alpha-D-galactopyranosyl)-D-glycero-pent-2-enono-1,4-lactone on the basis of its physical and chemical properties and its two hydrolytic products, D-galactose and D-erythroascorbic acid. Treatment of this galactoside with alkaline hydrogen peroxide produces oxalic acid as observed earlier with erythroascorbic acid.

Patterns of nucleotide misincorporations during enzymatic amplification and direct large-scale sequencing of ancient DNA.

Whereas evolutionary inferences derived from present-day DNA sequences are by necessity indirect, ancient DNA sequences provide a direct view of past genetic variants. However, base lesions that accumulate in DNA over time may cause nucleotide misincorporations when ancient DNA sequences are replicated. By repeated amplifications of mitochondrial DNA sequences from a large number of ancient wolf remains, we show that C/G-to-T/A transitions are the predominant type of such misincorporations. Using a massively parallel sequencing method that allows large numbers of single DNA strands to be sequenced, we show that modifications of C, as well as to a lesser extent of G, residues cause such misincorporations. Experiments where oligonucleotides containing modified bases are used as templates in amplification reactions suggest that both of these types of misincorporations can be caused by deamination of the template bases. New DNA sequencing methods in conjunction with knowledge of misincorporation processes have now, in principle, opened the way for the determination of complete genomes from organisms that became extinct during and after the last glaciation.

Transactivation of the epidermal growth factor receptor by cag+ Helicobacter pylori induces upregulation of the early growth response gene Egr-1 in gastric epithelial cells.

BACKGROUND AND AIMS: Helicobacter pylori, in particular cytotoxin associated gene (cag)+ strains, have been shown to enhance gastric epithelial cell proliferation in vivo, an effect that likely contributes to gastric carcinogenesis. Early growth response gene 1 (Egr-1) is a crucial regulator of cell growth, differentiation, and survival, which is known to play a role in carcinogenesis and cancer progression. The aims of this study were to: (1) examine whether H pylori could upregulate Egr-1 in gastric epithelial cell lines; (2) determine whether there was a differential response to infection with different strains; (3) examine the role of the cag pathogenicity island in this process; and (4) elucidate the molecular mechanisms leading to Egr-1 upregulation. METHODS AND RESULTS: We found that infection of AGS cells with cag+H pylori resulted in a rapid (1-2 hours) but transient increase in Egr-1 mRNA and protein levels whereas coculture with cag- isolates did not elicit this response. Furthermore, two independent cagE- isogenic mutants of H pylori also demonstrated impaired ability to upregulate Egr-1. Upregulation of Egr-1 protein was inhibited by the extracellular regulated kinase (ERK)1/2 inhibitor PD98059 and overexpression of dominant negative MEK1 downregulated Egr-1 luciferase reporter gene activity. Treatment of AGS cells with the epidermal growth factor receptor (EGFR) kinase inhibitors PD153035 and AG1478 resulted in a reduction in H pylori mediated Egr-1 upregulation, demonstrating that EGFR transactivation plays a role in this early cellular process. CONCLUSIONS: Our findings show that cag+H pylori cause rapid induction of Egr-1 in gastric epithelial cells which may contribute to H pylori mediated pathogenesis.

Enterocytes are the primary source of the chemokine ENA-78 in normal colon and ulcerative colitis.

Epithelial cell-derived neutrophil-activating protein-78 (ENA-78) is a neutrophil-directed C-X-C chemokine. We report that Caco-2 and T84 human intestinal epithelial cells produce ENA-78 after stimulation by interleukin (IL)-1 beta or tumor necrosis factor-alpha. Caco-2 cells show increased IL-8 production at 4-12 h and increased ENA-78 production at 8-24 h after cytokine stimulation. Immunohistochemical studies in normal human colon and in ulcerative colitis demonstrate ENA-78 immunoreactivity principally associated with crypt epithelial cells. Furthermore, human colonic tissues from patients with ulcerative colitis show elevated levels of ENA-78 mRNA (24-fold increase, P < 0.01) and protein (4-fold increase, P < 0.05) compared with normal controls. Thus ENA-78 is produced in normal colon and in ulcerative colitis and is predominantly of enterocyte origin. The kinetics of ENA-78 induction in human colon epithelial cell lines are delayed and prolonged compared with IL-8. We propose that ENA-78 and IL-8 serve complementary and sequential roles in neutrophil recruitment in ulcerative colitis. ENA-78 as an enterocyte-derived, neutrophil-activating chemokine may be especially important in neutrophil recruitment from the lamina propria into the epithelial layer.

Helicobacter pylori infection activates NF-kappa B in gastric epithelial cells.

BACKGROUND & AIMS: Helicobacter pylori adheres to gastric epithelial cells and stimulates interleukin (IL)-8 production. This may be instrumental in neutrophil infiltration of the gastric epithelium that characterizes H. pylori gastritis. This study examined the molecular mechanisms leading to H. pylori-induced epithelial cell IL-8 production. METHODS: Electrophoretic mobility shift analyses for NF-kappa B were performed on cell and nuclear extracts from H. pylori-infected AGS and Kato III human gastric epithelial cells. RESULTS: H. pylori infection activated the transcription factor NF-kappa B and induced nuclear translocation of both NF-kappa B p50/p65 heterodimers and p50 homodimers. Nuclear translocation of NF-kappa B (30 minutes) was followed by increased IL-8 messenger RNA (1 hour) and protein levels (4 hours) consistent with NF-kappa B up-regulation of IL-8 gene transcription. Pretreatment of AGS cells with PDTC, which blocks NF-kappa B activation, inhibited H. pylori-induced increases in IL-8 production by 90%. Immunohistochemical studies using a monoclonal antibody that recognizes the I-kappa B binding region of p65 showed activated NF-kappa B in gastric epithelial cells of patients with H. pylori gastritis. CONCLUSIONS: H. pylori infection activates NF-kappa B in gastric epithelial cells in vitro and in vivo. NF-kappa B is a transcriptional regulator of IL-8 production, and its activation after bacterial infection may be an important defense response in gastrointestinal epithelial cells.

Helicobacter pylori lipopolysaccharide binds to CD14 and stimulates release of interleukin-8, epithelial neutrophil-activating peptide 78, and monocyte chemotactic protein 1 by human monocytes.

Helicobacter pylori gastritis is characterized by leukocyte infiltration of the gastric mucosa. The aims of this study were to determine whether H. pylori-derived factors stimulate chemokine release from human monocytes and to ascertain whether H. pylori lipopolysaccharide (LPS) may be responsible for this effect. Human peripheral blood monocytes were exposed to an H. pylori water extract (HPE) or to purified H. pylori LPS. Levels of the chemokines interleukin-8 (IL-8), epithelial neutrophil-activating peptide 78 (ENA-78), and monocyte chemotactic protein 1 (MCP-1) were measured by enzyme-linked immunosorbent assay. The contribution of H. pylori LPS to monocyte activation was determined by using the LPS antagonist Rhodobacter sphaeroides lipid A (RSLA) and a blocking monoclonal antibody to CD14 (60bca). HPE increased monocyte secretion of IL-8, ENA-78, and MCP-1. Heat treatment of HPE did not reduce its ability to activate monocytes. Purified H. pylori LPS also stimulated monocyte chemokine production but was 1,000-fold less potent than Salmonella minnesota lipid A. RSLA blocked H. pylori LPS-induced monocyte IL-8 release in a dose-dependent fashion (maximal inhibition 82%, P < 0.001). RSLA also inhibited HPE-induced IL-8 release (by 93%, P < 0.001). The anti-CD14 monoclonal antibody 60bca substantially inhibited IL-8 release from HPE-stimulated monocytes (by 88%, P < 0.01), whereas the nonblocking anti-CD14 monoclonal antibody did not. These experiments with potent and specific LPS inhibitors indicate that the main monocyte-stimulating factor in HPE is LPS. H. pylori LPS, acting through CD14, stimulates human monocytes to release the neutrophil-activating chemokines IL-8 and ENA-78 and the monocyte-activating chemokine MCP-1. Despite its low relative potency, H. pylori LPS may play an important role in the pathogenesis of H. pylori gastritis.

Colonic epithelial cells are a major site of macrophage inflammatory protein 3alpha (MIP-3alpha) production in normal colon and inflammatory bowel disease.

BACKGROUND AND AIM: Macrophage inflammatory protein 3alpha (MIP-3alpha) is a recently described lymphocyte directed C-C chemokine expressed predominately at extralymphoid sites, including the intestine. The aim of this study was to determine whether colonic epithelial cells produce MIP-3alpha and whether its expression is upregulated in inflammatory bowel disease. METHODS AND RESULTS: We found that interleukin 1beta and tumour necrosis factor alpha dose dependently stimulated MIP-3alpha production in Caco-2 and HT-29 intestinal epithelial cells. In cytokine treated Caco-2 and HT-29 cells, a significant increase in MIP-3alpha protein production was observed after three hours and continued for at least 24 hours. Analysis of colonic tissues by quantitative real time polymerase chain reaction and ELISA revealed significantly elevated MIP-3alpha mRNA levels (7.9-fold; p<0.05) and protein levels (8.9-fold; p<0.05) in Crohn's disease compared with controls or ulcerative colitis. MIP-3alpha immunoreactivity in normal colon and inflammatory bowel disease was principally associated with crypt and surface epithelial cells. Moreover, MIP-3alpha protein levels were elevated in primary epithelial cells isolated from patients with inflammatory bowel disease. CONCLUSIONS: These findings indicate that increased enterocyte MIP-3alpha production may play an important role in lymphocyte activation and recruitment to the colonic epithelium in Crohn's disease and ulcerative colitis.

IL-8 secretion and neutrophil activation by HT-29 colonic epithelial cells.

This study examines the ability of HT-29 human colonic epithelial cells to stimulate neutrophil migration and adhesion. Interleukin-8 (IL-8), a potent neutrophil chemoattractant, was detected in conditioned media from both unstimulated (1.1 ng/ml) and IL-1 beta-stimulated (16.1 ng/ml) HT-29 cultures. Conditioned medium from IL-1 beta-exposed HT-29 cells stimulated neutrophil migration (395% of control, P < 0.01), and this effect was completely inhibited by anti-IL-8 antibody. HT-29 medium also induced shedding of neutrophil L-selectin and increased expression of neutrophil CD11/CD18 adhesion receptors. Coculture of HT-29 cells with human endothelial cell monolayers resulted in increased neutrophil transendothelial migration (169% of control, P < 0.01), which was blocked by both anti-IL-8 and anti-CD18 antibody. Northern hybridization analysis demonstrated increased levels of mRNA for IL-8 and intercellular adhesion molecule-1 (ICAM-1) in cytokine-treated HT-29 cells. Cytokine stimulation of HT-29 monolayers was also associated with increased neutrophil adhesion to these cells. Neutrophil-HT-29 cell adhesion was blocked by monoclonal antibodies to neutrophil CD18 or to ICAM-1 on the HT-29 cells (86% and 56% inhibition, respectively, P < 0.01 for both). These data suggest that IL-8 secretion by activated colonic epithelial cells may contribute to neutrophil extravasation and tissue infiltration in intestinal inflammation.

Intravenous immunoglobulin therapy for severe Clostridium difficile colitis.

BACKGROUND: Many individuals have serum antibodies against Clostridium difficile toxins. Those with an impaired antitoxin response may be susceptible to recurrent, prolonged, or severe C difficile diarrhoea and colitis. AIMS: To examine whether treatment with intravenous immunoglobulin might be effective in patients with severe pseudomembranous colitis unresponsive to standard antimicrobial therapy. PATIENTS: Two patients with pseudomembranous colitis not responding to metronidazole and vancomycin were given normal pooled human immunoglobulin intravenously (200-300 mg/kg). METHODS: Antibodies against C difficile toxins were measured in nine immunoglobulin preparations by ELISA and by cytotoxin neutralisation assay. RESULTS: Both patients responded quickly as shown by resolution of diarrhoea, abdominal tenderness, and distension. All immunoglobulin preparations tested contained IgG against C difficile toxins A and B by ELISA and neutralised the cytotoxic activity of C difficile toxins in vitro at IgG concentrations of 0.4-1.6 mg/ml. CONCLUSION: Passive immunotherapy with intravenous immunoglobulin may be a useful addition to antibiotic therapy for severe, refractory C difficile colitis. IgG antitoxin is present in standard immunoglobulin preparations and C difficile toxin neutralising activity is evident at IgG concentrations which are readily achieved in the serum by intravenous immunoglobulin administration.

Differential activation of mitogen-activated protein kinases in AGS gastric epithelial cells by cag+ and cag- Helicobacter pylori.

The aim of this study was to determine whether Helicobacter pylori activates mitogen-activated protein (MAP) kinases in gastric epithelial cells. Infection of AGS cells with an H. pylori cag+ strain rapidly (5 min) induced a dose-dependent activation of extracellular signal-regulated kinases (ERK), p38, and c-Jun N-terminal kinase (JNK) MAP kinases, as determined by Western blot analysis and in vitro kinase assay. Compared with cag+ strains, cag- clinical isolates were less potent in inducing MAP kinase, particularly JNK and p38, activation. Isogenic inactivation of the picB region of the cag pathogenicity island resulted in a similar loss of JNK and p38 MAP kinase activation. The specific MAP kinase inhibitors, PD98059 (25 microM; MAP kinase kinase (MEK-1) inhibitor) and SB203580 (10 microM; p38 inhibitor), reduced H. pylori-induced IL-8 production in AGS cells by 78 and 82%, respectively (p < 0.01 for each). Both inhibitors together completely blocked IL-8 production (p < 0.001). However, the MAP kinase inhibitors did not prevent H. pylori-induced IkappaBalpha degradation or NF-kappaB activation. Thus, H. pylori rapidly activates ERK, p38, and JNK MAP kinases in gastric epithelial cells; cag+ isolates are more potent than cag- strains in inducing MAP kinase phosphorylation and gene products of the cag pathogenicity island are required for maximal MAP kinase activation. p38 and MEK-1 activity are required for H. pylori-induced IL-8 production, but do not appear to be essential for H. pylori-induced NF-kappaB activation. Since MAP kinases regulate cell proliferation, differentiation, programmed death, stress, and inflammatory responses, activation of gastric epithelial cell MAP kinases by H. pylori cag+ strains may be instrumental in inducing gastroduodenal inflammation, ulceration, and neoplasia.

cag+ Helicobacter pylori induce transactivation of the epidermal growth factor receptor in AGS gastric epithelial cells.

The gastric pathogen Helicobacter pylori is known to activate epithelial cell signaling pathways that regulate numerous inflammatory response genes. The aim of this study was to elucidate the pathway leading to extracellular signal-regulated kinase (ERK) 1/2 phosphorylation in H. pylori-infected AGS gastric epithelial cells. We find that H. pylori, via activation of the epidermal growth factor (EGF) receptor activates the small GTP-binding protein Ras, which in turn, mediates ERK1/2 phosphorylation. cag+ strains of H. pylori are able to induce greater EGF receptor activation than cag- strains, and studies with isogenic mutants indicate that an intact type IV bacterial secretion system is required for this effect. Blockade of EGF receptor activation using tyrphostin AG1478 prevents H. pylori-mediated Ras activation, inhibits ERK1/2 phosphorylation, and substantially decreases interleukin-8 gene expression and protein production. Investigations into the mechanism of EGF receptor activation, using heparin, a metalloproteinase inhibitor and neutralizing antibodies reveal that H. pylori transactivates the EGF receptor via activation of the endogenous ligand heparin-binding EGF-like growth factor. Transactivation of gastric epithelial cell EGF receptors may be instrumental in regulating both proliferative and inflammatory responses induced by cag+ H. pylori infection.

IL-8 release and neutrophil activation by Clostridium difficile toxin-exposed human monocytes.

Neutrophil infiltration is central to the pathogenesis of Clostridium difficile toxin A-induced enterocolitis. This study examines whether monocyte activation by C. difficile toxins is instrumental in initiating neutrophil activation and recruitment. Human monocytes were exposed to low concentrations of highly purified C. difficile toxins, and the conditioned media were harvested for cytokine and functional assays. Monocytes exposed to C. difficile toxin A (10(-10) M) or toxin B (10(-12) M) released 100 and 20 times basal levels, respectively, of the neutrophil chemoattractant interleukin-8 (IL-8). Reverse transcriptase-polymerase chain reaction demonstrated a marked increase in IL-8 mRNA expression by monocytes 3 h after toxin exposure. Conditioned media from toxin A- and toxin B-treated monocytes stimulated neutrophil migration (324 and 245% of control, respectively). This effect was completely blocked by IL-8 antiserum. These media also upregulated neutrophil CD11b/CD18 and endothelial cell intercellular adhesion molecule-1 expression. C. difficile toxins, at low concentrations, potently activate monocytes to release factors, including IL-8, that facilitate neutrophil extravasation and tissue infiltration. Our findings indicate a major role for toxin-mediated monocyte and macrophage activation in C. difficile colitis.

Anti-Clostridium difficile bovine immunoglobulin concentrate inhibits cytotoxicity and enterotoxicity of C. difficile toxins.

Clostridium difficile diarrhea and colitis result from the actions of bacterial exotoxins on the colonic mucosa. This study examined the ability of hyperimmune bovine colostral antibodies to neutralize the biological effects of these toxins. Anti-C. difficile bovine immunoglobulin concentrate was prepared from the colostral milk of Holstein cows previously immunized with C. difficile toxoids. The anti-C. difficile bovine immunoglobulin concentrate contained high levels of bovine immunoglobulin G specific for C. difficile toxins A and B, as evaluated by enzyme-linked immunosorbent assay. Anti-C. difficile bovine immunoglobulin concentrate neutralized the cytotoxic effects of purified toxin A and toxin B on cultured human fibroblasts, whereas control bovine immunoglobulin concentrate had little toxin-neutralizing activity. Anti-C. difficile bovine immunoglobulin concentrate also blocked the binding of toxin A to its enterocyte receptor and inhibited the enterotoxic effects of C. difficile toxins on the rat ileum, as measured by an increased rat ileal loop weight/length ratio (63% inhibition; P < 0.01), increased mannitol permeability (92% inhibition; P < 0.01), and histologic grading of enteritis (P < 0.01 versus nonimmune bovine immunoglobulin concentrate). Thus, anti-C. difficile bovine immunoglobulin concentrate neutralizes the cytotoxic effects of C. difficile toxins in vitro and inhibits their enterotoxic effects in vivo. This agent may be clinically useful in the prevention and treatment of C. difficile diarrhea and colitis.

Survival of anti-Clostridium difficile bovine immunoglobulin concentrate in the human gastrointestinal tract.

To be therapeutically active, oral hyperimmune bovine immunoglobulin concentrate (BIC) must survive its passage through the intestinal tract. This led us to study the gastrointestinal stability of orally administered BIC directed against Clostridium difficile toxins (BIC-C. difficile). BIC-C. difficile was stable at neutral pH in vitro but was degraded at low pH, particularly in the presence of pepsin. Healthy volunteers (n = 6) took BIC-C. difficile (45 or 8 g) as a single oral dose. Total bovine immunoglobulin G (IgG) and specific anti-C. difficile IgG were measured in the stool. BIC was given under the following conditions: in the fasting state, in the fed state, with antacid, during omeprazole therapy, or in enteric capsules (released at pH > 6). The mean fecal bovine IgG content of 3-day stool collections was similar in the fasting (536 mg; 3.8% of the ingested dose of BIC), fed (221 mg; 1.6%), and antacid (381 mg; 2.7%) groups. Omeprazole therapy was associated with increased fecal bovine IgG levels (1253 mg; 8.8%), but this difference did not reach statistical significance (P = 0.07). Administration of 8 g of BIC-C. difficile in enteric capsules resulted in substantially higher fecal bovine IgG levels (1,124 mg; 32.7% of the oral dose) than those obtained after administration of nonencapsulated BIC (22 MG; 0.6%; P = 0.004). An inverse relationship was noted between intestinal transit time and fecal bovine IgG content (R = 0.83; P = 0.04 [data from omeprazole group]). Filtrates of stool samples collected after oral administration of BIC-C. difficile neutralized the cytotoxicity of C. difficile toxins A and B, whereas control stool filtrates did not. Bovine colostral IgG undergoes partial degradation in the intestinal tract. Exposure to acidic gastric secretions and prolonged colonic transit may both contribute to IgG degradation. Nonetheless, humans taking BIC-C. difficile orally have neutralizing antitoxin activity in their stool.

ZBP-89, Sp1, and nuclear factor-kappa B regulate epithelial neutrophil-activating peptide-78 gene expression in Caco-2 human colonic epithelial cells.

We reported previously that human colonic epithelial cells produce the C-X-C chemokine epithelial neutrophil-activating peptide-78 (ENA-78) and that its expression is up-regulated in ulcerative colitis. The aim of this study was to investigate the transcriptional regulation of ENA-78 gene expression in Caco-2 intestinal epithelial cells. Reporter gene transfection and electrophoretic mobility shift assay studies demonstrated that cooperation between two regions of the ENA-78 promoter were required for maximal gene expression in interleukin-1beta-stimulated Caco-2 cells. Binding of activated p50/p65 nuclear factor-kappaB to nucleotides -82 to -91 was essential for interleukin-1beta-dependent gene transcription, whereas binding of constitutively expressed zinc-requiring nuclear factors to nucleotides -125 to -134 (site A) was required for basal gene expression. Scanning mutagenesis of site A demonstrated overlapping binding elements at this locus. One site (CTCCCCC) bound Sp1 and Sp3, and overexpression of Sp1 (but not Sp3) up-regulated basal ENA-78 transcription. Another site (CCCCTCCCCC) was found to bind the zinc finger nuclear factor ZBP-89, and overexpression of this protein significantly repressed ENA-78 reporter gene activity. This study demonstrates that ENA-78 gene expression in Caco-2 intestinal epithelial cells is subject to complex regulation involving the coordinate binding of ZBP-89, Sp1, and nuclear factor-kappaB to the ENA-78 promoter.