Generation and evaluation of antibodies against human MGF E-peptide by reverse phase protein microarray and reverse competitive ELISA

Circulation autoantibodies against C-terminus of NuMA in patients with Behçet's disease

Circulating autoantibodies have a close association with autoimmune diseases, which may be seen even in healthy individuals. These are also considered as promising source of new biomarkers in various autoimmune diseases. However, their profile is not completely understood till now. Here, we evaluated autoantibodies against nuclear mitotic apparatus protein located at the carboxy terminus (C-NuMA)in blood circulation of Han Chinese patients, using different technical approaches to discover pathological reaction leading to Behçet's disease (BD). In the first step, the recombinant human carboxy-terminal region of NuMA peptide (C-NuMA) was over-expressed and purified. In the second step, the indirect immunofluorescence method was used with patients' sera, and commercial anti-NuMA antibody was used to determine the NuMA as a potential autoantigen. Results were confirmed at cell level by western blots, indicating that two of ten patients with Behçet's disease could react with the recombinant C-NuMA,and the presence of antibodies were further verified by immunoprecipitation technique. Finally, the corresponding immunoassay (ELISA) was developed and optimized with specific recombinant C-NuMA as an in vitro method to test the confirmed patients with Behçet's disease. Our findings demonstrated that C-terminus of NuMA is an immune target of Behçet's disease in Han Chinese patients.

Circulation autoantibody against Lamin A/C in patients with Sjögren's syndrome

Lamin A/C proteins are major components of nuclear laminae and were encoded by the LMNA gene. Recent studies have found that in addition to provides nuclear-membrane strength; it also regulates the gene expression. Lamin A/C has been confirmed as an autoantigen in RA, SLE and vasculitis. Anti-Lamin A/C antibodies also have been found by indirect immunofluorescence method. In this study, we used various research methods to confirm Lamin A/C is an autoantigen in Han Chinese patients with confirmed Sjögren's syndrome (SS). To further investigate the relationship between the autoimmune disease antigens, we compared the amino acid sequence of Lamin A/C epitope and several common antigens' antigenic determinant. As a result, we found that Lamin A/C has similar epitopes with U1RNP. It means that the potential relationship exist between Lamin A/C and U1RNP. Clinical data we collected also showed that anti-Lamin A/C and anti-U1RNP antibodies always appear in same serum sample. Therefore, we speculated that cross-reaction may take place between antigen and potential antigen, which have similar epitope. Then, by epitope spreading, the potential antigen can be a new autoantigen. Our study provided a new thinking for further research about the relationship between autoantigens and their development mechanism in autoimmune diseases.

Screening hybridomas for anabolic androgenic steroids by steroid analog antigen microarray

BACKGROUND

Currently, dozens of anabolic androgenic steroids (AAS) are forbidden in the World Anti-Doping Agency Prohibited List, however, despite extensive investigation, there are still lots of AAS without corresponding monoclonal antibodies.

RESULTS

A steroid analog antigen microarray made up of ten AAS was fabricated to screen the hybridoma and it was found an original unsuccessful clone turned out to be a candidate anti-boldenone antibody, without any cross-reactions with endogenous AAS or 44 different AAS standard reference materials tested.

CONCLUSION

Our findings suggested that steroid analog antigen microarray could be a promising tool to screen and characterize new applications of antibodies for structure analogs, and this also exhibits the potential to fast identify effective epitopes of hybridomas in a single assay.

Prohibitin Is Involved in Patients with IgG4 Related Disease

Objective

IgG4-related disease (IgG4-RD) is a chronic systemic disease involved in many organs and tissues. As only limited autoantigens have been found since the beginning of this century, the aim of this study was to reveal new candidate autoantigens of IgG4-RD.

Methods

Multiple cell lines including HT-29, EA.hy926, HEK 293 and HepG2 were used to test the binding ability of circulating autoantibodies from IgG4-RD sera. The amino-acid sequence was then analyzed by matrix-assisted laser desorption/ionization time-of-flight tandem (MALDI-TOF/TOF) mass spectrometry. After the cloning and expression of recombinant putative autoantigen in a bacterial expression system, the corresponding immuno assay was set up and utilized to observe the prevalence of serum autoantibodies in a large set of confirmed clinical samples.

Results

One positive autoantigen was identified as prohibitin. ELISA analysis showed that a majority of patients with IgG4-RD have antibodies against prohibitin. Anti-prohibitin antibodies were present in the sera of patients with definite autoimmune pancreatitis (25/34; 73.5%), Mikulicz’s disease (8/15; 53.3%), retroperitoneal fibrosis (6/11; 54.5%), other probable IgG4-RD (26/29; 89.7%) and Sjögren’s syndrome (4/30; 13.3%) but not in apparently healthy donors (1/70; 1.4%).

Conclusions

An association between prohibitin and patients with some IgG4-RD was observed, although the results were quite heterogeneous among different individuals within autoimmune pancreatitis, Mikulicz’s disease and retroperitoneal fibrosis.

Electron Transfer Flavoprotein Subunit Beta Is a Candidate Endothelial Cell Autoantigen in Behçet's Disease

Behçet’s disease (BD) is a chronic inflammatory disease with multisystem involvement, and it is listed as a rare disease in the United States but is common in the Middle East, China, and Japan. The aim of this study was to identify novel autoantigens in Chinese patients with BD. First, the candidate autoantigens were screened by Western blotting, and the sequences of putative antigens were identified by LC-MALDI-TOF/TOF mass spectrometry. Next, the screened protein was cloned, expressed and purified. Then, an optimized ELISA was developed, and the serological criteria were evaluated using a large number of confirmed patients. One antigen with a molecular weight of approximately 28 kDa was identified as electron transfer flavoprotein subunit beta (ETFB). Positive reactivity was detected in recombinant human ETFB sera from 38 of 92 BD patients (41 %) and 1 of 90 healthy controls (1 %).

Prohibitin as a novel autoantigen in rheumatoid arthritis

The aim of this study

The aim of this study was to verify whether prohibitin is a novel autoantigen in rheumatoid arthritis.

Material and methods

First, recombinant human prohibitin (rhPHB) protein was cloned, expressed, and purified. Then the anti-prohibitin autoantibodies were detected by western blotting by using rhPHB protein to incubate sera from patients with rheumatoid arthritis (RA). Next, immunoprecipitation was employed to further illustrate whether anti-prohibitin antibodies exist in RA patients. And finally, autoantibodies against the rhPHB protein were investigated using a homemade ELISA kit through the assessment of 258 real clinical samples.

Results

It was revealed that anti-prohibitin antibodies existed in the sera of patients with RA. Reactivity of serum IgG against rhPHB was detected in 26 of 86 RA patients (30.3%), 7 of 86 systemic lupus erythematosus (SLE) patients (8.1%), and 1 of 86 apparently healthy donors (HC) (1.2%).

Conclusions

Prohibitin was proved to be a novel autoantigen and the corresponding anti-prohibitin autoantibodies were present in the RA patients' blood circulation.

Annexin A2 as a target endothelial cell membrane autoantigen in Behçet's disease

Cell membrane proteins are believed to play a critical role in the pathogenesis of autoimmune diseases. However, few membrane autoantigens have been linked with Behçet's disease. Here, a cell-chip was performed to identify autoantibody target cells, and the suspected autoantigens were detected using immunoblotting. The amino acid sequences of the detected proteins were determined using LC-MALDI-TOF/TOF. Putative proteins were recombinantly expressed and purified, and a corresponding ELISA was developed and clinically validated using real clinical samples. It was found that a 36-kDa membrane protein--annexin A2--was detected in approximately one-third of the patients' blood circulation. The immunohistochemistry results showed that annexin A2 was highly expressed in vascular endothelial cells. Moreover, vascular involvement was significantly higher in the anti-annexin A2 antibody-positive group versus the anti-annexin A2 antibody-negative group among all the clinical samples analyzed, indicating that annexin A2 is a novel endothelial cell membrane antigen involved in Behçet's disease.

Identification of heat shock protein 27 as a novel autoantigen of Behçet's disease

OBJECTIVE

The aim of this study was to identify candidate pathogenic autoantigens of Behçet's disease (BD) in pathogen-stimulated target cells.

METHODS

First, three cell lines were used as target cells to screen autoantibody. Second, selected target cells were simulated with pathogens. Third, western blotting was used for detecting the auto-antigens in cell extracts. Next, immunoprecipitation was performed and the amino-acid sequences of target antigens were analyzed by LC-MALDI-TOF/TOF. Then, the potential target antigen was expressed, purified, and immunologically confirmed. And finally, an ELISA kit was developed and clinically validated through the assessments of 456 clinical samples with BD.

RESULTS

One antigen with a molecular weight of approximately 27-kDa was identified as heat shock protein 27 (HSP27). The reactivity of serum IgG against recombinant human HSP27 was detected in 52 of 91 BD patients (57%), 66 of 92 rheumatoid arthritis (RA) patients (72%), 32 of 90 Sjogren syndrome (SS) patients (36%), 22 of 92 systemic lupus erythematosus (SLE) patients (24%) and 0 of 91 healthy controls (HC). The reactivity of BD serum IgG antibodies against HSP27 was significantly higher than SLE (P<0.0001) SS (P<0.0001) and HC (P<0.0001).

CONCLUSIONS

This study identified HSP27 as a candidate endothelial cell autoantigen of BD, which is interesting and probably worth further exploration.

Identification of prohibitin as an antigen in Behcet's disease

OBJECTIVE

This study is intended to screen potential antigen for Behcet's disease (BD) by using human microvascular endothelial cells (HUVEC).

METHODS

Following cell-based indirect immunofluorescence assay with sera from BD patients, proteins extracted from HUVEC were separated and detected by Western blotting. Then the target protein was identified by LC-MALDI-TOF/TOF, the recombinant target protein was expressed, purified and then used as coating antigen to test the prevalence of autoantibodies in patient's sera.

RESULTS

The Western blotting result showed that some patients' sera could react with a protein band with about 30 kDa of molecular weight, which was further identified as prohibitin by mass spectrometry. The prevalence of serum antibodies against recombinant human prohibitin was detected in 16 of 58 BD patients (28%) but none in healthy controls.