Unknown,Transcriptomics,Genomics,Proteomics

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An antibody leukocyte capture microarray in diagnosis of Systemic Lupus Erythematosus

ABSTRACT: The diagnosis of Systemic Lupus Erythematosus (SLE) is challenging due to its heterogeneous clinical presentation and lack of robust biomarkers for laboratory testing to distinguish it from other autoimmune or infectious diseases. Current diagnostic criterion relies on a combination of clinical examination and laboratory tests, and it does not readily distinguish between those with active clinical disease from those that are clinically quiescent. Several groups have attempted to apply emerging high throughput profiling technologies to diagnose SLE. Despite showing promising diagnostic potential, many of them are expensive and technically challenging for routine clinical uses. Here we report a pilot study of applying a technically simple and highly customisable leukocyte capture antibody microarray to profile healthy (n=24) and SLE patients (n=60) of various disease activities. Our analysis reveals a set of surface antigen biomarkers that have significant association with SLE. In addition, we present a computational method to calculate a score from the entire microarray profile to obtain a score that correlate most reliably with SLE disease activity. Although the current version of our microarray alone does not match the discriminatory power of the standard laboratory tests (serum dsDNA, complements C3 and C4), the combination of the two yields a test with significantly increased discriminatory ability than what can be achieved individually. This work paves the way for a customised SLE-specific antibody microarray for accurate diagnosis and monitoring of SLE that can be readily translated to routine clinical use. Blood samples were collected from 60 patients of Systemic Lupus Erythematosus (SLE) of different disease activity (11 active, 16 semi-active, and 33 inactive), and compared it with blood samples from 24 healthy blood donors. For each subject, we extracted PBMCs and apply them to a leukocyte capture antibody microarray. The microarray was then scaned by a DotScan™ slide reader (Medsaic; Eveleigh, NSW, Australia). The number of immobilized cells was proportional to the light scattered at each antibody spot. Binding of PBMCs to each antibody dot was monitored by light scatter and averaged between the duplicate spots on each slide. We then performed statistical analysis to identify CD antigen markers that are associated with SLE, as well as determining the potential diagnostic ability of this microarray for SLE.

ORGANISM(S): Homo sapiens

SUBMITTER: Joshua Ho

PROVIDER: E-GEOD-27293 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:The study of disease-associated immune biomarkers has revealed underlying pathogenic mechanisms and provided diagnostic and prognostic values in numerous clinical settings. Accurate immune profiling of normal age and sex demographics is crucial for understanding the relevance of disease biomarkers. The incidence of age-associated diseases in the elderly and prevalence of diseases in specific genders may be explained by these normal phenotypic variation in the cellular immune system. Here we use microarrays of cluster of differentiation (CD) antibodies to immunophenotype populations of peripheral blood mononuclear cells (PBMCs) from healthy adult blood donors. The data revealed a set of statistically significant age- and gender-dependent expression patterns across the study population. We identified functional differences in immune biomarkers on PBMC associated with major innate, adaptive and inflammatory immune functions. The CD array data supported established observations using flow cytometric methods on age-associated changes in immune biomarkers, while also identifying novel markers associated with age and/or gender. The data demonstrates the utility of CD antibody arrays in providing a systematic and quantitative basis for understanding the development and progression of diseases that have an age-dependent and gender-specific etiology. Blood samples were collected from healthy male and female blood donors acrooss various age groups, predominantly Caucasians, from the Australian Red Cross Blood Service, Sydney, Australia, and from elderly males enrolled in the Concord Health and Aging in Men Project (CHAMP) at Concord Hospital, Sydney, Australia. PBMCs were fractionated from whole blood and applied to a cell capture CD antibody microarray. The microarray was then scaned by a DotScan™ slide reader (Medsaic; Eveleigh, NSW, Australia). The number of immobilized cells was proportional to the light scattered at each antibody spot. Binding of PBMCs to each antibody dot was monitored by light scatter and averaged between the duplicate spots on each slide. We then performed statistical analysis to identify CD antigen markers that has an statistically significant association with age and/or gender

Project description:Detection of immunogenic proteins remains an important task for life sciences as it nourishes the understanding of pathogenicity, illuminates new potential vaccine candidates and broadens the spectrum of biomarkers applicable in diagnostic tools. Traditionally, immunoscreenings of expression libraries via polyclonal sera on nitrocellulose membranes or screenings of whole proteome lysates in 2-D gel electrophoresis are performed. However, these methods feature some rather inconvenient disadvantages. Screening of expression libraries to expose novel antigens from bacteria often lead to an abundance of false positive signals owing to the high cross reactivity of polyclonal antibodies towards the proteins of the expression host. A method is presented that overcomes many disadvantages of the old procedures. We incorporated a fusion tag prior to our genes of interest and attached the expressed fusion proteins covalently on microarrays. This enhances the specific binding of the proteins compared to nitrocellulose. Thus, it helps to reduce the number of false positives significantly. It enables us to screen for immunogenic proteins in a shorter time, with more samples and statistical reliability. We validated our method by employing several known genes from Campylobacter jejuni NCTC 11168. Four of proteins that have previously been described as immunogenic have successfully been assessed immunogenic abilities with our method. One protein with no known immunogenic behaviour before suggested potential immunogenicity. The method presented offers a new approach for screening of bacterial expression libraries to illuminate novel proteins with immunogenic features. It could provide a powerful and attractive alternative to existing methods and help to detect and identify bacterial virulence factors, vaccine candidates and potential biomarkers. The overall study was done with five technical replicates. Ten proteins derived from Campylobacter jejuni were tested regarding their immunogenic potential. The ten proteins derived from Campylobacter jejuni were fusion proteins, i.e., N-terminal HaloTag fused to: Gene <--> Protein cjaA <--> putative amino-acid transporter periplasmic solute-binding protein hisJ <--> histidine-binding protein precursor pal <--> peptidoglycan associated lipoprotein flaC <--> flagellin flaA <--> flagellin peb1a <--> bifunctional adhesin/ABC transporter aspartate/glutamate-binding protein pyrC <--> dihydroorotase (EC:3.5.2.3) pseB <--> UDP-GlcNAc-specific C4,6 dehydratase/C5 epimerase gapA <--> glyceraldehyde 3-phosphate dehydrogenase (EC:1.2.1.12) argC <--> N-acetyl-gamma-glutamyl-phosphate reductase (EC:1.2.1.38)

Project description:The screening of a cDNA derived expression library of Salmonella Enteritidis 125109 expressed in E. coli using a fusion construct and specific HaloTag interaction to a modified surface is shown. Thus, 1536 different clones were screened including positive (fimA) and negative (argC, gapA) reference proteins. The goal of the screening was to identify potential novel immunogenic proteins from S. Enteritidis by selecting clones showing a high signal intensity in comparison to the known antigens used as positve markers. Afterwards, the most promising clones were sequenced to identify the gene and corresponding protein and these proteins were then investigated further. Consequently, 9 novel immunogenic proteins could be identified. In total 1536 different lysates were spotted on different microarray slides. Each slides contained 3600 distinct spots, seperated into two compartments of 1800 spots each. Each compartment comprised quadruplicate replicates of each sample lysate with controls being analysed with more replicates. As controls we used: fimA from 3 different samples (40 replicates) as positive reference proteins, as it has been described as immunogenic before. GapA from Klebsiella pneumoniae and Campylobacter jejuni (40 replicates) as negative reference proteins, additionally two sets of E.coli cell lysates without fusionprotein expressed, namely Acella electrocompetent cells (40 replicates) and KRX (32 replicates). Last but not least a buffer control (24 replicates) was included. Therefore, each set of replicate slides contained 384 different samples. Each screening was performed with three replicate slides. Consequently, a total number of 12 slides were screened (4 sets of samples x 3 replicates each). For identification rabbit polyclonal antibody to S. enterica (Abcam ab35156) as primary and Goat polyclonal to Rabbit IgG conjugated with ChromeoTM-546 (Abcam ab60317) as secondary antibody were used. The top compartment was incubated first with primary antibody, while the bottom compartment was incubated with PBS at the same time. Afterwards both compartments were incubated with secondary antibody.

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An antibody leukocyte capture microarray in diagnosis of Systemic Lupus Erythematosus

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