Phase I dose finding studies of an adjuvanted Clostridium difficile toxoid vaccine.

Fifty healthy adult (18-55 years) and 48 elderly (≥ 65 years) volunteers were randomized to receive a candidate Clostridium difficile toxoid vaccine (2 μg, 10 μg, or 50 μg) or placebo on Days 0, 28, and 56. No volunteer receiving placebo seroconverted. For toxin A, seroconversion by Day 56 (post-dose 2) was observed in 100% of volunteers aged 18-55 years in all dose groups and in 50%, 89%, and 100% of elderly participants in the 2 μg, 10 μg, and 50 μg dose groups, respectively.

Physical characterization of clostridium difficile toxins and toxoids: effect of the formaldehyde crosslinking on thermal stability.

Nosocomial diarrhea and pseudomembranous colitis causing toxins A and B from Clostridium difficile were studied at pH 5-8 and over the temperature range of 10-85 degrees C. The proteins were crosslinked with formaldehyde to inactivate them to toxoid forms and permit their use as vaccines. Structural changes and aggregation behavior were monitored with circular dichroism, intrinsic and extrinsic (ANS) fluorescence spectroscopy, turbidity measurements, high-resolution UV absorbance spectroscopy and dynamic light scattering.

Preformulation studies of Clostridium difficile toxoids A and B.

To enhance the physical stability of Clostridium difficile toxoids A and B, screening for stabilizing compounds was performed. The screening of 30 GRAS compounds at various concentrations and in several combinations was performed in two parts. First, a high-throughput aggregation assay was used to screen for compounds which delayed or prevented aggregation of toxoids under stress conditions (toxoids at pH 5-5.

Extracellular nucleotides mediate LPS-induced neutrophil migration in vitro and in vivo.

Extracellular nucleotides are emerging as important inflammatory mediators. Here, we demonstrate that these molecules mediate LPS-induced neutrophil migration in vitro and in vivo. Apyrase, a nucleotide scavenger, reduced the ability of LPS-stimulated monocytes to recruit neutrophils, as assayed using a modified Boyden chamber.

Toxin production by an emerging strain of Clostridium difficile associated with outbreaks of severe disease in North America and Europe.

Background: Toxins A and B are the primary virulence factors of Clostridium difficile. Since 2002, an epidemic of C difficile-associated disease with increased morbidity and mortality has been present in Quebec province, Canada. We characterised the dominant strain of this epidemic to determine whether it produces higher amounts of toxins A and B than those produced by non-epidemic strains.

Heme oxygenase-1-generated biliverdin ameliorates experimental murine colitis.

Background: Heme oxygenase-1 (HO-1) seems to have an important protective role in acute and chronic inflammation. The products of heme catalysis, biliverdin/bilirubin, carbon monoxide (CO), and iron (that induces apoferritin) mediate the beneficial effects of HO-1. Blockade of HO-1 activity results in exacerbation of experimental colitis.

Clostridium difficile toxoid vaccine in recurrent C. difficile-associated diarrhea.

Background & Aims: Recurrent C difficile -associated diarrhea (CDAD) is associated with a lack of protective immunity to C difficile toxins. A parenteral C difficile vaccine containing toxoid A and toxoid B was reported previously to be safe and immunogenic in healthy volunteers. Our aim was to examine whether the vaccine is also well tolerated and immunogenic in patients with recurrent CDAD.

Interleukin 8 secretion from monocytes of subjects heterozygous for the deltaF508 cystic fibrosis transmembrane conductance regulator gene mutation is altered.

Patients with cystic fibrosis (CF) exhibit an excessive host inflammatory response. The aim of this study was to determine (i) whether interleukin 8 (IL-8) secretion is increased from monocytes from subjects heterozygous as well as homozygous for cystic fibrosis transmembrane conductance regulator (CFTR) mutations and (ii) whether this is due to increased cell surface lipopolysaccharide (LPS) receptors or, alternatively, increased activation of mitogen-activated protein kinases (MAPK). The basal level of IL-8 secretion was higher from monocytes from CF patients than from monocytes from healthy controls (P = 0.

Active and passive immunization against Clostridium difficile diarrhea and colitis.

Clostridium difficile, a gram-positive bacterium, is the major cause of hospital-acquired infectious diarrhea and colitis in industrialized nations. C. difficile colonization results from antibiotic administration and subsequent loss of protection provided by intestinal flora.

Clostridium difficile vaccine and serum immunoglobulin G antibody response to toxin A.

There is a strong association between serum antibody responses to toxin A and protection against Clostridium difficile diarrhea. A parenteral C. difficile toxoid vaccine induced very-high-level responses to anti-toxin A immunoglobulin G (IgG) in the sera of healthy volunteers.