Extracellular bacterial compounds as mediators of lactic acid bacteria-target cell interaction

VIRGINIA RODRIGUEZ; GUILLERMO JUAREZ; GRACIELA FONT; JULIO VILLENA

Probiotics: Immunobiotics and Immunogenics

CRC Press

Año: 2013;

A considerable amount of published data, some of which have been reported here and in other review articles, indicates that several surface and extracellular components of immunobiotic lactobacilli can influence host’s immune system. However, up to date there is no molecular information about the indentity of such compounds. In addition, detailed information of the molecular mechanism of action of these immunomodulatory compounds is needed. Our research work with L. reuteri CRL1098 constitutes the first studies shedding light on the evidence about the involvement of lipid rafts in the modulation of cytokine production induced by soluble factors of a beneficial LAB. It has become apparent that processes of raft-based domain regulation at the plasma membrane are directly coupled to spatial and temporal control of signaling. Thus, local raft recruitment and raft domain assembly mediate spatial control of signaling in response to extracellular signals. Because of the key roles played by lipid rafts in coupling local molecular organizations to signaling at membranes, the results of our studies will be of major importance to a mechanistic understanding of the immunomodulatory effect of LAB soluble factors. Moreover, the knowledge of lipid rafts participation in the response induced by L. reuteri CRL1098 opens new possibilities for studying the mechanisms involved in the interaction of LAB with the host immune cells. The main challenge for the future involves achieving a better understanding of raft-mediated regulation at the molecular level. The study of extracellular proteins may provide novel strategies for the clinical application of probiotic bacteria and may allow understanding of their mechanism of action; particularly the intervention of lipid rafts in cellular response induced by probiotics proteins and peptides. These proteins may present a powerful therapeutic approach in the treatment of several diseases associated with these microdomians. Further research is needed to elucidate the precise molecular mechanism of action of each of these proteins in both IECs and immune cells, notably in DCs.