Automated evaluation of autoantibodies on human epithelial-2 cells as an approach to standardize cell-based immunofluorescence tests

INTRODUCTION: Analysis of autoantibodies (AAB) by indirect immunofluorescence (IIF) is a basic tool for the serological diagnosis of systemic rheumatic disorders. Automation of autoantibody IIF reading including pattern recognition may improve intra- and inter-laboratory variability and meet the demand for cost-effective assessment of large numbers of samples. Comparing automated and visual interpretation, the usefulness for routine laboratory diagnostics was investigated. METHODS: Autoantibody detection by IIF on human epithelial-2 (HEp-2) cells was conducted in a total of 1222 consecutive sera of patients with suspected systemic rheumatic diseases from a university routine laboratory (n = 924) and a private referral laboratory (n = 298). IIF results from routine diagnostics were compared with a novel automated interpretation system. RESULTS: Both diagnostic procedures showed a very good agreement in detecting AAB (kappa = 0.828) and differentiating respective immunofluorescence patterns. Only 98 (8.0%) of 1222 sera demonstrated discrepant results in the differentiation of positive from negative samples. The contingency coefficients of chi-square statistics were 0.646 for the university laboratory cohort with an agreement of 93.0% and 0.695 for the private laboratory cohort with an agreement of 90.6%, P < 0.0001, respectively. Comparing immunofluorescence patterns, 111 (15.3%) sera yielded differing results. CONCLUSIONS: Automated assessment of AAB by IIF on HEp-2 cells using an automated interpretation system is a reliable and robust method for positive/negative differentiation. Employing novel mathematical algorithms, automated interpretation provides reproducible detection of specific immunofluorescence patterns on HEp-2 cells. Automated interpretation can reduce drawbacks of IIF for AAB detection in routine diagnostics providing more reliable data for clinicians

Over-Expression of LEDGF/p75 in HEp-2 Cells Enhances Autoimmune IgG Response in Patients with Benign Prostatic Hyperplasia : A Novel Diagnostic Approach with Therapeutic Consequence?

Lens epithelium-derived growth factor splice variant of 75 kDa (LEDGF/p75) is an autoantigen over-expressed in solid tumors and acts as a stress-related transcriptional co-activator. Participation of autoimmune responses in the pathophysiology of benign prostatic hyperplasia (PBH) and a corresponding immunosuppressive therapy by TNFalpha antagonists has been recently suggested. Thus, autoAb testing could aid in the diagnosis of BPH patients profiting from such therapy. We generated CRISPR/Cas9 modified HEp-2 LEDGF knock-out (KO) and HEp-2 LEDGF/p75 over-expressing (OE) cells and examined IgG autoantibody reactivity to LEDGF/p75 in patients with prostate cancer (PCa, n = 89), bladder cancer (BCa, n = 116), benign prostatic hyperplasia (BPH, n = 103), and blood donors (BD, n = 60) by indirect immunofluorescence assay (IFA). Surprisingly, we could not detect elevated binding of autoAbs against LEDGF/p75 in cancer patients, but autoAb reactivity to LEDGF/p75 OE cells in about 50% of patients with BPH was unexpectedly significantly increased. Furthermore, a line immunoassay enabling the detection of 18 different autoAbs revealed a significantly increased occurrence of anti-dsDNA autoAbs in 34% of BPH patients in contrast to tumor patients and BD. This finding was confirmed by anti-mitochondrial (mDNA) autoAb detection with the Crithidia luciliae immunofluorescence test, which also showed a significantly higher prevalence (34%) of anti-mDNA autoAbs in BPH. In summary, our study provided further evidence for the occurrence of autoimmune responses in BPH. Furthermore, LEDGF/p75 over-expression renders HEp-2 cells more autoantigenic and an ideal target for autoAb analysis in BPH with a potential therapy consequence

Species-specific and pathotype-specific binding of bacteria to zymogen granule membrane glycoprotein 2 (GP2)

With interest we read the paper by Juste et al 1 proposing the amount of zymogen-granule membrane glycoprotein 2 (GP2) on the surface of intestinal bacteria as a Crohn\u27s disease (CD) marker. Indeed, a decreased GP2 level was found on microbes in patients with CD as compared to those of healthy controls. GP2 is a homologue to the urinary Tamm–Horsefall protein demonstrating an antimicrobial function by binding type 1-fimbriated uropathogenic Escherichia coli (UPEC). Likewise, GP2 seems to interact with intestinal bacteria as a specific receptor of bacterial type-1 fimbriae (FimH) on intestinal microfold cells that are partaking in immune responses against such microbes.2 GP2 is overexpressed in the inflamed intestine of patients with CD and has an immunomodulating role in innate and acquired immune responses.3 ,4Interestingly, GP2 was identified as autoantigen of pancreatic antibodies in CD.4 Altogether, these findings indicate two major GP2 sources (pancreatic/intestinal) and support a role for GP2 in the interaction between the immune system and intestinal microbiota.3 Thus, loss of tolerance to GP2 could play a role in CD\u27s pathophysiology supposed to be exacerbated by preceding intestinal infections. In general, the findings by Juste et al 1 may be explained by a lower pancreatic GP2 secretion, an impaired GP2 binding to bacteria, or by a higher prevalence of bacteria with poor or no GP2 binding in patients with CD

Porcine E. coli: Virulence-Associated Genes, Resistance Genes and Adhesion and Probiotic Activity Tested by a New Screening Method

We established an automated screening method to characterize adhesion of Escherichia colito intestinal porcine epithelial cells (IPEC-J2) and their probiotic activity against infection by enteropathogenic E. coli (EPEC). 104 intestinal E. coli isolates from domestic pigs were tested by PCR for the occurrence of virulence-associated genes, genes coding for resistances to antimicrobial agents and metals, and for phylogenetic origin by PCR. Adhesion rates and probiotic activity were examined for correlation with the presence of these genes. Finally, data were compared with those from 93 E. coli isolates from wild boars. Isolates from domestic pigs carried a broad variety of all tested genes and showed great diversity in gene patterns. Adhesions varied with a maximum of 18.3 or 24.2 mean bacteria adherence per epithelial cell after 2 or 6 hours respectively. Most isolates from domestic pigs and wild boars showed low adherence, with no correlation between adhesion/probiotic activity and E. coli genes or gene clusters. The gene sfa/foc, encoding for a subunit of F1C fimbriae did show a positive correlative association with adherence and probiotic activity; however E. coliisolates from wild boars with the sfa/foc gene showed less adhesion and probiotic activity thanE. coli with the sfa/foc gene isolated from domestic pigs after 6 hour incubation. In conclusion, screening porcine E. coli for virulence associated genes genes, adhesion to intestinal epithelial cells, and probiotic activity revealed a single important adhesion factor, several probiotic candidates, and showed important differences between E. coli of domestic pigs and wild boars

Virulence-associated genes, resistance genes and adhesion and probiotic activity tested by a new screening method

We established an automated screening method to characterize adhesion of Escherichia coli to intestinal porcine epithelial cells (IPEC-J2) and their probiotic activity against infection by enteropathogenic E. coli (EPEC). 104 intestinal E. coli isolates from domestic pigs were tested by PCR for the occurrence of virulence-associated genes, genes coding for resistances to antimicrobial agents and metals, and for phylogenetic origin by PCR. Adhesion rates and probiotic activity were examined for correlation with the presence of these genes. Finally, data were compared with those from 93 E. coli isolates from wild boars. Isolates from domestic pigs carried a broad variety of all tested genes and showed great diversity in gene patterns. Adhesions varied with a maximum of 18.3 or 24.2 mean bacteria adherence per epithelial cell after 2 or 6 hours respectively. Most isolates from domestic pigs and wild boars showed low adherence, with no correlation between adhesion/probiotic activity and E. coli genes or gene clusters. The gene sfa/foc, encoding for a subunit of F1C fimbriae did show a positive correlative association with adherence and probiotic activity; however E. coli isolates from wild boars with the sfa/foc gene showed less adhesion and probiotic activity than E. coli with the sfa/foc gene isolated from domestic pigs after 6 hour incubation. In conclusion, screening porcine E. coli for virulence associated genes genes, adhesion to intestinal epithelial cells, and probiotic activity revealed a single important adhesion factor, several probiotic candidates, and showed important differences between E. coli of domestic pigs and wild boars

New Platform Technology for Comprehensive Serological Diagnostics of Autoimmune Diseases

Antibody assessment is an essential part in the serological diagnosis of autoimmune diseases. However, different diagnostic strategies have been proposed for the work up of sera in particular from patients with systemic autoimmune rheumatic disease (SARD). In general, screening for SARD-associated antibodies by indirect immunofluorescence (IIF) is followed by confirmatory testing covering different assay techniques. Due to lacking automation, standardization, modern data management, and human bias in IIF screening, this two-stage approach has recently been challenged by multiplex techniques particularly in laboratories with high workload. However, detection of antinuclear antibodies by IIF is still recommended to be the gold standard method for antibody screening in sera from patients with suspected SARD. To address the limitations of IIF and to meet the demand for cost-efficient autoantibody screening, automated IIF methods employing novel pattern recognition algorithms for image analysis have been introduced recently. In this respect, the AKLIDES technology has been the first commercially available platform for automated interpretation of cell-based IIF testing and provides multiplexing by addressable microbead immunoassays for confirmatory testing. This paper gives an overview of recently published studies demonstrating the advantages of this new technology for SARD serology

E. coli Nissle 1917 Affects Salmonella Adhesion to Porcine Intestinal Epithelial Cells

BACKGROUND: The probiotic Escherichia coli strain Nissle 1917 (EcN) has been shown to interfere in a human in vitro model with the invasion of several bacterial pathogens into epithelial cells, but the underlying molecular mechanisms are not known. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we investigated the inhibitory effects of EcN on Salmonella Typhimurium invasion of porcine intestinal epithelial cells, focusing on EcN effects on the various stages of Salmonella infection including intracellular and extracellular Salmonella growth rates, virulence gene regulation, and adhesion. We show that EcN affects the initial Salmonella invasion steps by modulating Salmonella virulence gene regulation and Salmonella SiiE-mediated adhesion, but not extra- and intracellular Salmonella growth. However, the inhibitory activity of EcN against Salmonella invasion always correlated with EcN adhesion capacities. EcN mutants defective in the expression of F1C fimbriae and flagellae were less adherent and less inhibitory toward Salmonella invasion. Another E. coli strain expressing F1C fimbriae was also adherent to IPEC-J2 cells, and was similarly inhibitory against Salmonella invasion like EcN. CONCLUSIONS: We propose that EcN affects Salmonella adhesion through secretory components. This mechanism appears to be common to many E. coli strains, with strong adherence being a prerequisite for an effective reduction of SiiE-mediated Salmonella adhesion

Stable expression of human muscle-specific kinase in HEp-2 M4 cells for automatic immunofluorescence diagnostics of myasthenia gravis.

Muscle-specific kinase (MuSK) belongs to the nicotinic acetylcholine receptor complex which is targeted by pathogenic autoantibodies causing Myasthenia gravis. While up to 95% of patients with generalized Myasthenia gravis were shown to be positive for acetylcholine receptor-specific autoantibodies, up to 70% of the remaining patients develop autoantibodies against MuSK. Discrimination of the autoantibody specificity is important for therapy of Myasthenia gravis. Recently, the new automatic fluorescence assessment platform AKLIDES has been developed for immunofluorescence-based diagnostics of autoimmune diseases. In order to establish an AKLIDES procedure for the detection of MuSK-specific autoantibodies (anti-MuSK), we developed a recombinant HEp-2 cell clone expressing the human MuSK cDNA. Here we show at the mRNA and protein level that the cell clone HEp-2 M4 stably expresses human MuSK. We provide evidence for a localization of MuSK at the cell membrane. Using cell clone HEp-2 M4 on the AKLIDES system, we investigated 34 patient sera that were previously tested anti-MuSK positive by radioimmunoassay as positive controls. As negative controls, we tested 29 acetylcholine receptor-positive but MuSK-negative patient sera, 30 amytrophic lateral sclerosis (ALS) patient sera and 45 blood donors. HEp-2 M4 cells revealed a high specificity for the detection of MuSK autoantibodies from 25 patient sera assessed by a specific pattern on HEp-2 M4 cells. By using appropriate cell culture additives, the fraction of cells stained positive with anti-MuSK containing sera can be increased from 2-16% to 10-48%, depending on the serum. In conclusion, we provide data showing that the novel recombinant cell line HEp-2 M4 can be used to screen for anti-MuSK with the automatic AKLIDES system

Der CytoBead-Assay – Eine neue Möglichkeit der multiparametrischen Autoantikörperanalytik bei systemischen Autoimmunerkrankungen

Bei Verdacht auf Vorliegen einer systemischen Autoimmunerkrankung wird für die serologische Routinediagnostik ein Zwei-Stufen-Verfahren empfohlen. Zuerst werden Autoantikörpern (AAK) mittels sensitiver zellbasierter indirekter Immunfluoreszenz (IIF)-Teste bestimmt. Ein positives Ergebnis muss aufgrund der Möglichkeit von falsch-positiven Ergebnissen mit einem weiteren, spezifischen Test bestätigt werden. Dieses sukzessive Vorgehen ist notwendig, da zurzeit keine Assaytechnik die notwendigen Anforderungen an ein einstufiges Verfahren hinsichtlich Sensitivität und Spezifität erfüllt. Im Sinne einer effektiven AAK-Diagnostik kann heute schon eine simultane Bestimmung von mehreren AAK mittels multiparametrischer Bestätigungstests die Diagnosefindung im Vergleich zu konventionellen, monoparametrischen Tests wesentlich verkürzen. Jedoch erlauben die verfügbaren multiparametrischen AAK-Nachweismethoden nicht die Kombination von Screening- und Bestätigungstesten. Deshalb wurde basierend auf der digitalen Fluoreszenz mit der hier vorgestellten CytoBead Technologie ein neuer Ansatz entwickelt. Ziel war die Kombination der empfohlenen Stufendiagnostik bestehend aus sensitivem Screening und spezifischer Bestätigungsdiagnostik in einer Reaktionsumgebung und darüber hinaus die Möglichkeit der Adaption auf die serologische Diagnostik mehrerer Autoimmunerkrankungen. Durch a) die Nutzung von Standardglasobjektträgern, b) die Kombination von nativen zellulären oder Gewebesubstraten mit antigenbeladenen fluoreszierenden Mikropartikeln (Beads) in einer Reaktionsumgebung, c) die Möglichkeit der manuellen und automatischen Auswertung mittels IIF und d) die Erhebung von quantitativen Fluoreszenzmessergebnissen konnten die Nachteile der bisher bestehenden Testsysteme überwunden werden. Das neue Prinzip ist auf verschiedene multiparametrische AAK-Nachweise wie zum Beispiel die Bestimmung von antinukleären Antikörpern und AAK gegen entsprechende nukleäre und zytoplasmatische autoantigene Zielstrukturen anwendbar. Damit wurde weiterhin die Basis für die simultane AAK-Multiparameterbestimmung für die Serologie der Zöliakie und von ANCA-assoziierten systemischen Vaskulitiden geschaffen