Abstract
In addition to the well-known role of adipose tissue in energy metabolism, it has recently been demonstrated that this tissue can secrete a large array of molecules, including inflammatory cytokines. Furthermore, recent studies suggest that adipose cells can behave as immune cells. Therefore, the aim of this study was to determine the presence of the two most prominent ‘pattern recognition receptors’ for bacterial and fungal cell wall components, TLR2 and TLR4 on human adipose cells, as well as to assess their functionality. We demonstrated that TLR2 and TLR4 were expressed at relatively high levels (compared to a monocyte cell line) on the surface of human adipose cells. Stimulation of human adipocytes with lipopolysaccharide (LPS), or with lipoteichoic acid (LTA), two specific ligands of TLR4 and TLR2, respectively, induced a strong increase in TNFα production. The specificity of the response was demonstrated by the use of anti-TLR4 and anti-TLR2 blocking antibodies, which were able to decrease LPS- or LTA-induced TNFα secretion. Thus, it is clear that these receptors are functional in human adipocytes. This study adds weight to the argument that human fat tissue plays a potential role in innate immunity.
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Acknowledgments
We are grateful to patient volunteers and reconstructive surgery departments (CHD Félix Guyon, Saint-Denis) for supplying adipose tissue. This work was supported by grants from the Ministère de l’Outre Mer, Ministère de l’Enseignement Supérieur et de la Recherche, and the Conseil Régional de La Réunion. We would like to thank the plastic surgeons J. F. Baron, P. Delarue and J. Gonçalves who took part in this study and allowed the collection of subcutaneous adipose tissue samples.
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Sandrine Bés-Houtmann, Régis Roche, Christian Lefebvre d’Hellencourt and Maya Cesari have contributed equally to this work.
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Bès-Houtmann, S., Roche, R., Hoareau, L. et al. Presence of functional TLR2 and TLR4 on human adipocytes. Histochem Cell Biol 127, 131–137 (2007). https://doi.org/10.1007/s00418-006-0230-1
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DOI: https://doi.org/10.1007/s00418-006-0230-1