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Open Access Highly Accessed Research article

Identification of tuberculosis-associated proteins in whole blood supernatant

Takahiro Tanaka12, Shinsaku Sakurada2, Keiko Kano3, Eri Takahashi35, Kazuki Yasuda4, Hisashi Hirano5, Yasushi Kaburagi3, Nobuyuki Kobayashi6, Nguyen Thi Le Hang7, Luu Thi Lien8, Ikumi Matsushita2, Minako Hijikata2, Takafumi Uchida1 and Naoto Keicho2*

Author Affiliations

1 Molecular Enzymology, Graduate School of Agricultural Science, Tohoku University, 1-1 Amamiya-machi, Tsutsumidori, Aoba-ku, Sendai, Miyagi 981-8555, Japan

2 Department of Respiratory Diseases, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, Japan

3 Department of Diabetic Complications, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, Japan

4 Department of Metabolic Disorder, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, Japan

5 Supramolecular Biology, International Graduate School of Art and Sciences, Yokohama City University, 1-7-29 Suehirocho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan

6 Department of Respiratory Medicine, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, Japan

7 National Center for Global Health and Medicine - Bach Mai Hospital (NCGM-BMH) Medical Collaboration Center, 78 Giai Phong St., Hanoi, Vietnam

8 Hanoi Tuberculosis and Lung Disease Hospital, 44 Thanh Nhan Road, Hanoi, Vietnam

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BMC Infectious Diseases 2011, 11:71  doi:10.1186/1471-2334-11-71

Published: 22 March 2011

Abstract

Background

Biological parameters are useful tools for understanding and monitoring complicated disease processes. In this study, we attempted to identify proteins associated with active pulmonary tuberculosis (TB) using a proteomic approach.

Methods

To assess TB-associated changes in the composition of human proteins, whole blood supernatants were collected from patients with active TB and healthy control subjects. Two-dimensional difference gel electrophoresis (2D-DIGE) was performed to analyze proteins with high molecular weights (approximately >20 kDa). Baseline protein levels were initially compared between patients with active TB and control subjects. Possible changes of protein patterns in active TB were also compared ex vivo between whole blood samples incubated with Mycobacterium tuberculosis (Mtb)-specific antigens (stimulated condition) and under unstimulated conditions. Immunoblot and enzyme-linked immunosorbent assays (ELISA) were performed to confirm differences in identified proteins.

Results

Under the baseline condition, we found that the levels of retinol-binding protein 4 (RBP4), fetuin-A (also called α-HS-glycoprotein), and vitamin D-binding protein differed between patients with active TB and control subjects on 2D gels. Immunoblotting results confirmed differential expression of RBP4 and fetuin-A. ELISA results further confirmed significantly lower levels of these two proteins in samples from patients with active TB than in control subjects (P < 0.0001). Mtb-specific antigen stimulation ex vivo altered clusterin expression in whole blood samples collected from patients with active TB.

Conclusions

We identified TB-associated proteins in whole blood supernatants. The dynamics of protein expression during disease progression may improve our understanding of the pathogenesis of TB.