Identification of peptides specific for antibodies in vitiligo using a phage library

Differential expression of mRNA for T-bet and GATA-3 transcription factors in peripheral blood mononuclear cells of patients with vitiligo

BACKGROUND

There is accumulating evidence that aberrant T helper (Th)1 and Th2 cell responses play critical roles in the pathogenesis of autoimmune diseases. However, their importance in the pathobiology of vitiligo have yet to be elucidated.

AIM

To evaluate the expression profile of two transcription factors, namely, T-bet, a Th1-specific T box transcription factor and GATA binding protein 3 (GATA-3), a Th2-specific transcription factor, and to measure expression levels of interferon (IFN)-γ and interleukin (IL)-4 mRNAs as the signature cytokines of Th1 and Th2 cells, respectively.

METHODS

Gene expression analysis of peripheral blood mononuclear cells (PBMCs) was performed using real-time reverse transcriptase PCR.

RESULTS

In patients with vitiligo compared with controls, mRNA expression was significantly higher for T-bet and IFN-γ, and significantly lower for GATA-3 and IL-4 mRNAs (P ≤ 0.05).

CONCLUSION

These data suggest additional implications for the role of Th1/Th2 balance in the immunopathogenesis of vitiligo.

Unravelling autoimmune pathogenesis by screening random peptide libraries with human sera

The incidence of autoimmunity is increasing worldwide. The long preclinical period of autoimmune disorders is characterised by an enhanced exposure over time of autoreactive T cells to an increased number of autoantigenic determinants and autoantibodies production. The discovery of novel autoimmune-disease related epitopes is a task that remains extremely challenging in order to establish predictive and preventive strategies of the disease onset. In this Opinion article we highlight the contribution of screening combinatorial random peptide libraries with patients sera in unravelling the etiopathogenesis of autoimmunity.

Mapping of melanin-concentrating hormone receptor 1 B cell epitopes predicts two major binding sites for vitiligo patient autoantibodies

The melanin-concentrating hormone receptor 1 (MCHR1) has been identified as a B cell autoantigen in vitiligo with antibodies to the receptor detectable in binding and function-blocking assays. Two epitope domains (amino acids 1-138 and 139-298) have been previously identified. In this study, we aimed to further define the epitope specificity of MCHR1 antibodies using phage-display technology and to identify the epitopes recognised by receptor antibodies detected in MCHR1 function-blocking assays. Antibody reactivity to MCHR1 peptides 51-80, 85-98, 154-158 and 254-260 was identified by phage-display and subsequently confirmed in phage ELISA in 2/12, 5/12, 3/12 and 6/12 of vitiligo patients, respectively. The results suggest that major autoantibody epitopes are localised in the 85-98 and 254-260 amino acid regions of MCHR1 with minor epitopes in amino acid sequences 51-80 and 154-158. Antibodies with MCHR1 function-blocking activity were determined to recognise epitope 254-260, this being the first epitope to be reported as a target site for antibodies that block the function of the receptor.