S-layer glycoprotein from Lactobacillus kefiri CIDCA 8348 enhances macrophages response to LPS in a Ca+2-dependent manner
- Cátedra de Microbiología, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), La Plata (Argentina)
- Laboratorio de Inmunomodulación y Desarrollo de Vacunas, Departamento de Inmunobiología, Facultad de Medicina, UdelaR, Montevideo (Uruguay)
Highlights: • S-layer protein of L. kefiri CIDCA 8348 (SLP8348) is recognized by ConA. • Uptake of SLP8348 by murine macrophages is inhibited by glucose, mannose and EGTA. • SLP8348 significantly increased LPS-induced response of macrophages. • SLP8348-LPS synergism is abrogated by EGTA, indicating a role of Ca{sup +2} in the effect. • Results suggest the potentiality of SLP8348 for development of new adjuvants. The S-layer is a (glyco)-proteinaceous envelope constituted by self-assembled subunits that form a two-dimensional lattice covering the surface of different species of Bacteria and Archaea. It could be considered as one of the most abundant biopolymers in our planet. Because of their unique self-assembly features, exhibiting repetitive identical physicochemical properties down to the subnanometer scale, as well as their involvement in specific interactions with host cells, the S-layer proteins (SLPs) show a high potential application in different areas of biotechnology, including the development of antigen carriers or new adjuvants. The presence of a glycosylated SLP on potentially probiotic Lactobacillus kefiri strains was previously described by our research group. In this study, we aim to investigate the role of carbohydrates present in the SLP from L. kefiri CIDCA 8348 (SLP-8348) in their internalization by murine macrophages, as well as to analyze their immunomodulatory capacity and their effect on LPS-stimulated macrophages. RAW 264.7 cells internalized the SLP-8348 in a process that was mediated by carbohydrate-receptor interactions since it was inhibited by glucose, mannose or EGTA, a Ca{sup +2} chelating agent. These results correlated with the recognition of SLP-8348 by ConA lectin. We further show that while SLP-8348 was not able to induce the activation of macrophages by itself, it favored the LPS-induced response, since there was a significant increase in the expression of surface cell markers MHC-II, CD86 and CD40, as well as in IL-6 and IL-10 expression at both transcript and protein levels, in comparison with LPS-stimulated cells. The presence of EGTA completely abrogated this synergistic effect. Taken together, these results strongly suggest the involvement of both glycosidic residues and Ca{sup +2} ions in the recognition of SLP-8348 by cellular receptors on murine macrophages. Moreover, these results suggest the potentiality of the SLP-8348 for the development of new adjuvants capable of stimulating antigen presenting cells by interaction with glycan receptors.
- OSTI ID:
- 23134443
- Journal Information:
- Biochemical and Biophysical Research Communications, Vol. 495, Issue 1; Other Information: Copyright (c) 2017 Elsevier Inc. All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0006-291X
- Country of Publication:
- United States
- Language:
- English
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