Additive effect of recombinant Mycobacterium tuberculosis ESAT-6 protein and ESAT-6/CFP-10 fusion protein in adhesion of macrophages through fibronectin receptors

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• 作者：Mina Hemmati^a ; ^b ; ^e ; Atefeh Seghatoleslam^a ; ^c ; ^e ; Mozhgan Rasti^a ; Saeedeh Ebadat^a ; Fakhraddin Naghibalhossaini^a ; Zohreh Mostafavi-Pour^a ; ^d ; ^{zmostavaripour88@yahoo.co.uk" class="auth_mail" title="E-mail the corresponding author}
• 关键词：early secreted antigenic target-6/culture filtrate protein-10 fusion protein ; integrin ; Mycobacterium tuberculosis
• 刊名：Journal of Microbiology, Immunology and Infection
• 出版年：2016
• 出版时间：April 2016
• 年：2016
• 卷：49
• 期：2
• 页码：249-256
• 全文大小：1239 K

文摘

Tuberculous granulomas are the sites of interaction between the T cells, macrophages, and extracellular matrix (ECM) to control the infection caused by Mycobacterium tuberculosis (M. tuberculosis). A predominant role of RD-1-encoded secretory proteins, early secreted antigenic target-6 (ESAT-6), and culture filtrate protein-10 (CFP-10) in the formation of granulomas has recently been emphasized. However, the precise molecular events that induce the formation of these granulomatous structures are yet to be elucidated. Macrophages use integrins to adhere to fibronectin (FN) as a major component of the ECM. The major goal of this study was to investigate whether recombinant M. tuberculosis antigens can modulate integrin-mediated macrophage adhesion.

Methods

Differentiated THP-1 cell line was stimulated with recombinant ESAT-6, CFP-10, and ESAT-6/CFP-10 proteins and evaluated for alterations in the expression levels of α₅β₁ and α₄β₁ by semiquantitative real-time polymerase chain reaction. The role of these recombinant antigens in the cytoskeleton rearrangement was determined by adhesion assay and immunofluorescent microscopy.

Results

Our data showed that ESAT-6 and ESAT-6/CFP-10 fusion proteins could induce adhesion of macrophages to FN through α₄β₁ integrin. An increased expression level of α₄β₁ integrin in comparison with α₅β₁ integrin in differentiated THP-1 cells was also observed. Results of immunofluorescence studies showed that recombinant proteins-treated THP-1 cells form well-organized stress fibers and focal contacts containing vinculin compared with untreated THP-1 cells.

Conclusion

Increased expression level of α₄β₁ in differentiated THP-1 cells could suggest the important role of α₄β₁ integrin in adhesion and focal contact formation of macrophages exposed to M. tuberculosis antigens.