Altered T Cell Migratory Capacity in the Progression from Barrett Oesophagus to Oesophageal Adenocarcinoma.

Oesophageal adenocarcinoma (OAC) is an inflammation-driven cancer with poor prognosis and incidence is increasing rapidly. OAC arises from gastro-oesophageal reflux disease (GORD) and reflux-induced Barrett oesophagus (BO). The role of T cells in this disease progression is not yet fully understood. We have previously demonstrated higher proportions of pro-tumour Th2 cells in BO tissue, implicating them in its pathogenesis. While a Th2 immune profile is thought to underlie the metaplastic transformation in BO and promote OAC development, our studies suggest that the abundance of Th2 cells in BO tissue is likely to occur through altered T cell recruitment. This study examined the chemokine networks governing T cell migration to oesophageal tissue during disease progression. Here, we have identified that circulating T cells in OAC patients, exhibit impaired migratory capacity with decreased frequencies of Th1-associated CXCR3+ and Th17-associated CCR6+ cells. Despite the abundance of Th1 chemokines RANTES (CCL5) and MIP-1α (CCL3) in OAC tumour, enrichments of intratumoural T cells expressing corresponding receptors were not observed. These data suggest that T cell infiltration of oesophageal tissue is compromised in OAC and suggest that future therapies targeting T cell trafficking should occur at the pre-neoplastic stage. This is supported by the finding that antagonism of Th2-biased CCR4 significantly reduces T cell migration in BO but not OAC patients. Since we have previously reported a predominant Th2 immune profile in BO, we suggest that chemokine receptor antagonism may be a viable treatment option to alleviate Th2-predominance in BO and interrupt progression to OAC.

The microenvironment of visceral adipose tissue and liver alter natural killer cell viability and function.

The role of NK cells in visceral adipose tissue (VAT) and liver inflammation in obesity is not fully understood. This study investigated the frequency, cytokine expression, chemokine receptor, and cytotoxicity receptor profile of NK cells in the blood, omentum, and liver of patients with the obesity-associated cancer, oesophageal adenocarcinoma (OAC). The effect of chronically inflamed tissue microenvironments on NK cell viability and function was also examined. We identified significantly lower NK cell frequencies in the liver of OAC patients compared with healthy controls and within the omentum and liver of OAC patients compared with blood, whereas IL-10-producing populations were significantly higher. Interestingly, our data suggest that reduced frequencies of NK cells in omentum and liver of OAC patients are not a result of impaired NK cell chemotaxis to these tissues. In fact, our functional data revealed that secreted factors from omentum and liver of OAC patients induce significant levels of NK cell death and lead to reduced percentages of TNF-α+ and NKP46+ NK cells and higher frequencies of IL-10-producing NK cells. Together, these data suggest that the omental and hepatic microenvironments of OAC patients alter the NK cell phenotype to a more anti-inflammatory homeostatic role.

CCR1 antagonism attenuates T cell trafficking to omentum and liver in obesity-associated cancer.

Obesity is a global health problem presenting serious risk of disease fuelled by chronic inflammation, including type 2 diabetes mellitus, cardiovascular disease, liver disease and cancer. Visceral fat, in particular the omentum and liver of obese individuals are sites of excessive inflammation. We propose that chemokine-mediated trafficking of pro-inflammatory cells to the omentum and liver contributes to local and subsequent systemic inflammation. Oesophagogastric adenocarcinoma (OAC) is an exemplar model of obesity and inflammation driven cancer. We have demonstrated that T cells actively migrate to the secreted factors from the omentum and liver of OAC patients and that both CD4(+) and CD8(+) T cells bearing the chemokine receptor CCR5 are significantly more prevalent in these tissues compared to matched blood. The CCR5 ligand and inflammatory chemokine MIP-1α is also secreted at significantly higher concentrations in the omentum and liver of our OAC patient cohort compared to matched serum. Furthermore, we report that MIP-1α receptor antagonism can significantly reduce T cell migration to the secreted factors from OAC omentum and liver. These novel data suggest that chemokine receptor antagonism may have therapeutic potential to reduce inflammatory T cell infiltration to the omentum and liver and in doing so, may ameliorate pathological inflammation in obesity and obesity-associated cancer.

Self-Powered Microfluidic Device for Rapid Assay of Antiplatelet Drugs.

We report the development of a microfluidic device for the rapid assay in whole blood of interfacial platelet-protein interactions indicative of the efficacy of antiplatelet drugs, for example, aspirin and Plavix, two of the world's most widely used drugs, in patients with cardiovascular disease (CVD). Because platelet adhesion to surface-confined protein matrices is an interfacial phenomenon modulated by fluid shear rates at the blood/protein interface, and because such binding is a better indicator of platelet function than platelet self-aggregation, we designed, fabricated, and characterized the performance of a family of disposable, self-powered microfluidic chips with well-defined flow and interfacial shear rates suitable for small blood volumes (≤200 µL). This work demonstrates that accurate quantification of cell adhesion to protein matrices, an important interfacial biological phenomenon, can be used as a powerful diagnostic tool in those with CVD, the world's leading cause of death. To enable such measurements, we developed a simple technique to fabricate single-use self-powered chips incorporating shear control (SpearChips). These parallel-plate flow devices integrate on-chip vacuum-driven blood flow, using a predegassed elastomer component to obviate active pumping, with microcontact-printed arrays of 6-µm-diameter fluorescently labeled fibrinogen dots on a cyclic olefin polymer base plate as a means to quantitatively count platelet-protein binding events. The use of SpearChips to assess in whole blood samples the effects of GPIIb/IIIa and P2Y12 inhibitors, two important classes of "antiplatelet" drugs, is reported.

Differential internalin A levels in biofilms of Listeria monocytogenes grown on different surfaces and nutrient conditions.

Listeria monoctyogenes is a foodborne pathogen containing the surface protein, internalin A (InlA). The expression of this protein permits the invasion of L. monocytogenes into intestinal epithelial cells expressing the receptor E-cadherin, thus crossing the intestinal barrier and resulting in listerosis. The main aim of this work was to investigate InlA levels in different L. monocytogenes strains in both planktonic and sessile states using an anti-InlA antibody. Biofilms were grown in high and low nutrient environments on glass, stainless steel and polytetrafluoroethylene (PTFE). This study demonstrated that InlA levels varied greatly between strains and serotypes of L. monocytogenes. However, the serotypes 1/2a, 1/2b and 4b, associated with the largest number of outbreaks of listerosis consistently showed the highest InlA levels, regardless of nutrient content or planktonic or sessile state. Differences in InlA levels were also observed in biofilms grown on different surfaces such as glass, stainless steel and PTFE, with a significant reduction in InlA levels observed in biofilms on PTFE. Interestingly, although a large number of the total cells observed in biofilms formed in tap-water were non-cultivable, the virulence factor, InlA, was expressed at levels between 78 and 85%, thus indicating that these cells may still be virulent. A greater understanding of the factors that affect the levels of InlA on the surface of L. monocytogenes, is essential in the appreciation of the role of InlA in the persistence of biofilms containing L. monocytogenes and their potential to cause food borne disease.

Impact of the inflammatory microenvironment on T-cell phenotype in the progression from reflux oesophagitis to Barrett oesophagus and oesophageal adenocarcinoma.

The incidence of oesophageal adenocarcinoma (OAC), arising from reflux-induced Barrett oesophagus (BO), is increasing dramatically. T-cells have recently been implicated in the initiation of oesophagitis; however, their role in the progression from oesophagitis to BO and OAC has not been fully elucidated. Previous studies have examined the secreted cytokines from oesophageal tissue during disease progression but this study is the first to examine the activation phenotype and the inflammatory profile of CD4(+) and CD8(+) T-cells in human oesophagitis, BO and OAC tissue. Results demonstrated significantly higher levels of IL-4 producing CD4(+) T-cells and secreted levels of IL-6, confirming a Th2 phenotype in BO. In OAC tissue, both pro- and anti-inflammatory cytokines were secreted, with significantly higher levels of IL-6, IL-1ß, TNF-α, IFN-γ, IL-2 and IL-10 compared with normal oesophageal tissue. In addition, CD4(+) T-cells infiltrating OAC tissue displayed a decreased activation profile, with significantly lower CD45RO and CD69 expression compared with normal tissue. Data from this study suggest that factors in the tissue microenvironment may alter T-cell phenotype and function early during oesophageal disease progression and may represent targets for immune intervention.

Microfiber coupler based label-free immunosensor.

Optical microfibers and related structures which incorporate large evanescent field and minimal size offer new opportunities for biosensing applications. In this paper we report the development of an immunosensor based on a tapered microfiber coupler embedded in a low refractive index polymer. Biomolecules adsorbed on the microfiber coupler surface modify the surrounding refractive index. By immobilizing antigens on the surface of the sensing area, the microfiber coupler was able to operate as a label-free immunosensor to detect specific antibodies. We experimentally demonstrated for the first time the sensing ability of this sensor using a fibrinogen antigen-antibody pair. By monitoring the spectral shift in the wavelength domain, the sensor was shown to be capable of detecting the specific binding between fibrinogen and anti-fibrinogen. The detected signal was found to be proportional to the anti-fibrinogen present.

Nanobiotechnologies for the detection and reduction of pathogens.

Advances in the manipulation of nanomaterials has permitted the development of nanobiotechnology with enhanced sensitivities and improved response times. Low levels of infection of the major pathogens require the need for sensitive detection platforms and the properties of nanomaterials make them suitable for the development of assays with enhanced sensitivity, improved response time and increased portability. Nanobiotechnologies focusing on the key requirements of signal amplification and pre-concentration for the development of sensitive assays for food-borne pathogen detection in food matrices will be described and evaluated. The potential that exists for the use of nanomaterials as antimicrobial agents will also be examined.

Generation of an anti-NAGase single chain antibody and its application in a biosensor-based assay for the detection of NAGase in milk.

Bovine mastitis, an inflammation of the mammary gland in cows, is a major challenge for the dairy industry worldwide as it lowers milk yield, reduces milk quality and increases overall production costs. Early diagnosis is of the utmost importance. N-acetyl-ß-D-glucosaminidase (NAGase) is an enzyme released into milk during inflammation and acts as an early indicator of mastitis. This paper describes the selection of anti-NAGase single chain fragment variable antibodies (scFv) from naïve human antibody libraries and their incorporation into an automated optical biosensor-based immunoassay to detect NAGase in milk. The scFv with the highest affinity for NAGase was first characterized by inhibition ELISA, followed by further evaluation using a surface plasmon resonance platform. Purified NAGase was immobilized on the surface of a CM5 chip and spiked NAGase milk samples were analyzed. The limit of detection for the assay for the assay was determined as 1µg/ml.

The increasing importance of carbon nanotubes and nanostructured conducting polymers in biosensors.

The growing need for analytical devices requiring smaller sample volumes, decreased power consumption and improved performance have been driving forces behind the rapid growth in nanomaterials research. Due to their dimensions, nanostructured materials display unique properties not traditionally observed in bulk materials. Characteristics such as increased surface area along with enhanced electrical/optical properties make them suitable for numerous applications such as nanoelectronics, photovoltaics and chemical/biological sensing. In this review we examine the potential that exists to use nanostructured materials for biosensor devices. By incorporating nanomaterials, it is possible to achieve enhanced sensitivity, improved response time and smaller size. Here we report some of the success that has been achieved in this area. Many nanoparticle and nanofibre geometries are particularly relevant, but in this paper we specifically focus on organic nanostructures, reviewing conducting polymer nanostructures and carbon nanotubes.

Mastitis detection: current trends and future perspectives.

Bovine mastitis, the most significant disease of dairy herds, has huge effects on farm economics due to reduction in milk production and treatment costs. Traditionally, methods of detection have included estimation of somatic cell counts, an indication of inflammation, measurement of biomarkers associated with the onset of the disease (e.g. the enzymes N-acetyl-beta-D-glucosaminidase and lactate dehydrogenase) and identification of the causative microorganisms, which often involves culturing methods. These methods have their limitations and there is a need for new rapid, sensitive and reliable assays. Recently, significant advances in the identification of nucleic acid markers and other novel biomarkers and the development of sensor-based platforms have taken place. These novel strategies have shown promise, and their advantages over the conventional tests are discussed.

Antibody-based sensors: principles, problems and potential for detection of pathogens and associated toxins.

Antibody-based sensors permit the rapid and sensitive analysis of a range of pathogens and associated toxins. A critical assessment of the implementation of such formats is provided, with reference to their principles, problems and potential for 'on-site' analysis. Particular emphasis is placed on the detection of foodborne bacterial pathogens, such as Escherichia coli and Listeria monocytogenes, and additional examples relating to the monitoring of fungal pathogens, viruses, mycotoxins, marine toxins and parasites are also provided.

Novel AroA with high tolerance to glyphosate, encoded by a gene of Pseudomonas putida 4G-1 isolated from an extremely polluted environment in China.

Glyphosate has been used globally as a safe herbicide for weed control. It inhibits 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase (AroA), which is a key enzyme in the aromatic amino acid biosynthetic pathway in microorganisms and plants. A Pseudomonas putida strain, 4G-1, was isolated from a soil heavily contaminated by glyphosate in China. Its AroA-encoding gene (aroA) has been cloned, sequenced, and expressed in Escherichia coli. Phylogenetic analysis revealed that this AroA belongs neither to class I nor to class II AroA enzymes. When compared with E. coli AroA, 4G-1 AroA shows similar values for K(m)[PEP], K(m)[S3P], and specific enzyme activity. Moreover, 4G-1 AroA exhibits high tolerance to glyphosate, which indicates a protein with a high potential for structural and functional studies of AroA in general and its potential usage for the generation of transgenic crops resistant to the herbicide.

Analysis of the C-terminal domain of Burkholderia sp. strain LB400 BphK reveals a conserved motif that affects catalytic activity.

The bphK gene encoding glutathione S-transferase (GST) is located in the bph operon (PCB co-metabolism) in Burkholderia sp. strain LB400 and the enzyme has recently been shown to have dechlorination activity in relation to 4-chlorobenzoate (4-CBA). Alignments using other glutathione S-transferase sequences found in PCB degradation operons identified a highly conserved region in the C-terminal domain of these enzymes that included a conserved motif implicated in protein folding in eukaryotic GSTs. Site-directed mutagenesis indicated that the region is indirectly involved in the catalytic activity and substrate specificity of BphK. Predicted hydrogen bond interactions involving Asp155 play an important role in the enzymatic properties of this glutathione S-transferase.

BphK shows dechlorination activity against 4-chlorobenzoate, an end product of bph-promoted degradation of PCBs.

A bphK gene encoding glutathione S-transferase (GST) activity is located in the bph operon in Burkholderia sp. strain LB400 but its role in polychlorinated biphenyl (PCB) metabolism is unknown. This gene was over-expressed in Escherichia coli and an in vivo assay based on growth of E. coli containing GST activity was used to identify potential novel substrates for this enzyme. Using this assay, 4-chlorobenzoate (4-CBA) was identified as a substrate for the BphK enzyme. High pressure liquid chromatography analysis and chloride ion detection showed removal of 4-CBA and an equivalent increase of chloride in cell extracts when incubated with this enzyme. These results would indicate that this BphK enzyme has dechlorination activity in relation to 4-CBA and may have a role in protection of other Bph enzymes against certain chlorinated metabolites of PCB degradation.