Prevalence and diversity of Escherichia coli isolated from a barley trial supplemented with bulky organic soil amendments: green compost and bovine slurry.

UNLABELLED: A barley field trial supplemented with bulky organic soil amendments, municipal compost or bovine slurry was sampled for Escherichia coli to test the hypothesis that E. coli isolated from the soil or from barley plants were derived from bovine slurry. A qualitative analysis showed that a total of 12% of the bulk soil cores and 16% of harvested grain samples yielded E. coli. The strongest association for positive detection of E. coli from soil was with time of year and for slurry-treated plots, with irrigation. However, E. coli were detected in plots from all treatment types and not exclusively associated with bovine slurry. Phylogroup, plasmid profiling and population genetics analysis (multilocus sequence typing) revealed extensive genetic diversity. Identical sequence types for slurry and soil isolates were detected, indicative of direct transfer into the soil, although not frequently. Host interaction assays with selected isolates showed a variation in the ability to colonize barley roots, but not in interactions with bovine cells. The work has implications in appropriate use of E. coli as a faecal indicator as isolates were widespread and diverse, reinforcing the view that some are a natural part of the microflora in agricultural systems. SIGNIFICANCE AND IMPACT OF THE STUDY: Faecal deposition is considered to be the main process that introduces Escherichia coli into soil, giving rise to their use as a faecal indication species and the potential for cycling pathogens in agricultural systems. We found that bovine slurry was not the main source of E. coli in a barley trial and a high degree of diversity was present in the collection. The findings support the hypothesis that the population structure of E. coli in secondary habitats is shaped by the environment and highlight the drawbacks of its use as a faecal indicator species.

ANCA-stimulated neutrophils release BLyS and promote B cell survival: a clinically relevant cellular process.

OBJECTIVES: To determine a role for antineutrophil cytoplasmic antibody (ANCA)-activated neutrophils in promoting B cell survival through the release of B lymphocyte stimulator (BLyS). METHODS: Neutrophil BLyS expression was measured by flow cytometry. Concentrations of BLyS in cell supernatants and donor serum samples were measured by ELISA. Cell survival assays were carried out using an L3055 cell line and viability measured by flow cytometry. RESULTS: Tumour necrosis factor α and formyl-Met-Leu-Phe (fMLP) treatment of non-primed neutrophils and treatment of primed neutrophils with anti-PR3 ANCA IgG resulted in a significant increase in surface expression of BLyS within 30 min which returned to basal levels by 2 h. Supernatants from ANCA-stimulated neutrophils were shown to contain increased levels of BLyS and to promote the survival of the centroblast cell line L3055. Serum BLyS concentrations are increased in patients with active ANCA-associated systemic vasculitis and these levels are increased further following 1-3 months of treatment with rituximab. CONCLUSIONS: ANCA specifically causes the release of BLyS from activated neutrophils which can support B cell survival in vitro. The presence of serum BLyS in active disease and its increase following B cell depletion suggest it is an important factor in disease pathogenesis and may facilitate disease relapse.

A study of matrix metalloproteinase expression and activity in atopic dermatitis using a novel skin wash sampling assay for functional biomarker analysis.

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin condition that is characterized by a defective skin barrier. Despite the well-recognized role of proteases in skin barrier maintenance, relatively little is known of the contribution made by matrix metalloproteinases (MMPs) to the inflammatory process in AD. OBJECTIVES: To test a simple, novel ex vivo bioassay technique in an analysis of the MMPs present in wash samples taken from the skin surface of patients with AD. METHODS: Saline wash samples were collected from eczematous and unaffected areas of the skin of patients with AD and from the skin of normal controls. Wash samples were analysed for their MMP content using a functional peptide cleavage assay, gelatin zymography and an antibody array. RESULTS: Using a functional substrate cleavage assay, skin wash samples from AD lesions were shown to contain 10- to 24-fold more MMP activity than those from normal control skin (P < 0.02) and fivefold more than those from unaffected AD skin (P < 0.05); this activity was inhibited by a broad-spectrum MMP inhibitor Ro 31-9790. Gelatin zymography and antibody array analysis revealed substantial levels of MMP-8 (neutrophil collagenase) and MMP-9 (92-kDa gelatinase) in AD skin wash samples as well as lower levels of MMP-10 (stromelysin 2) and tissue inhibitor of metalloproteinases (TIMP)-1 and TIMP-2; low levels of MMP-1 (fibroblast collagenase), MMP-3 (stromelysin 1) and TIMP-4 were also detected. CONCLUSIONS: A simple skin wash technique suitable for the quantitative and functional analysis of biomolecules in AD is described. Using this method we show that MMPs, and in particular MMP-8 and MMP-9, represent an important potential component of the pathology of AD. The method is expected to prove useful in advancing our understanding of AD and in identifying biomarkers for the evaluation of new therapies.

Dendritic cells from control but not atopic donors respond to contact and respiratory sensitizer treatment in vitro with differential cytokine production and altered stimulatory capacity.

BACKGROUND: Chemical haptens induce both contact and allergic respiratory disease with dendritic cells (DCs) controlling and directing immune responses in vivo. Contact and respiratory haptens may promote differential cytokine production yet distinguishing these effects in vitro remains difficult due to human donor variability. Objective We sought to determine the effect of atopic status on the ability of DC to respond to contact and respiratory sensitizer treatment in vitro as DC from atopic donors are believed to promote Th2-type responses. METHODS: Enriched DC from control or atopic donors were treated for 4 h with levels of the contact sensitizer 2,4-dinitrochlorobenzene (DNCB) or the respiratory sensitizer trimellitic anhydride (TMA) that did not reduce cell viability. A sensitive intracellular detection technique was used to measure cytokine production, while T cell responses were assessed in a mixed leucocyte reaction. RESULTS: DC from control, non-atopic, donors produced cytokines differentially in response to sensitizer treatment; DNCB treatment significantly increased the production of Th1 cytokines IL-12 and IFN-gamma while TMA induced the production of IL-13. Control donor DC treated with TMA stimulated less in a mixed leucocyte reaction than untreated cells with any response reduced further by blocking IL-13 in culture. However, DC from atopic donors showed no significant alteration in either cytokine production or T cell stimulatory capacity after sensitizer treatment. CONCLUSION: Haptens modulate DC by changing the production of cytokines that may play a role in T cell stimulation and subsequent polarization of the immune response. DC from atopic donors were unresponsive to chemical sensitizer treatment, and may be deficient in inducing divergent T cell responses.

PapB paralogues and their effect on the phase variation of type 1 fimbriae in Escherichia coli.

Recent work has demonstrated that expression of type 1 fimbriae is repressed by PapB, a regulator of pyelonephritis-associated pili (P-pili). PapB belongs to family of related adhesin regulators, for which consensus residues required for DNA binding and oligomerization have been identified. Of the regulators tested in this study, PapB, SfaB (S-fimbriae) and PefB (Salmonella enterica serovar Typhimurium--plasmid-encoded fimbriae) repressed FimB-promoted off-to-on inversion of the fim switch, although complete repression was only demonstrated by PapB. DaaA, FaeB, FanA, FanB and ClpB had no effect on fim switching. In addition, only PapB stimulated FimE-promoted on-to-off inversion. Deletion analysis demonstrated that this specificity resides in the carboxy terminal of the protein, and not the amino terminal, with the central region being homologous among the family members. Exchange of Leu(82) and Ile(83) of PapB for the equivalent residues from the DaaA protein (Phe and Gln) within the carboxy terminal virtually abolished cross-talk activity. Whereas PapB can bind to a region around the left inverted repeat of the fim switch, DaaA and the PapB double mutant were effectively unable to bind this region. A previously characterized PapB DNA binding mutant also failed to bind to this region and failed to inhibit FimB activity at the fim switch. Thus, repression of fim expression appears unique to PapB and SfaB within E. coli and requires DNA binding involving amino acid residues located both within the homologous core and in the heterogeneous carboxy terminus. The variation in the carboxy terminus between the PapB family members explains their differential effects on fim. This mechanism of cross-talk seems restricted to the P and S family adhesins with type 1 fimbriae and may ensure variable and sequential expression of adhesins during urinary tract infections.