Hypoxia reduces the response of human adipocytes towards TNFα resulting in reduced NF-κB signaling and MCP-1 secretion
| Autor: | A Horrighs, A Cramer, Susanne Famulla, Jürgen Eckel, Henrike Sell |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Vascular Endothelial Growth Factor A
medicine.medical_specialty Endocrinology Diabetes and Metabolism medicine.medical_treatment Down-Regulation Medicine (miscellaneous) Adipokine Adipose tissue Enzyme-Linked Immunosorbent Assay Real-Time Polymerase Chain Reaction chemistry.chemical_compound Internal medicine Adipocyte Adipocytes medicine Humans Obesity Hypoxia Chemokine CCL2 Nutrition and Dietetics Adiponectin Tumor Necrosis Factor-alpha NF-kappa B Hypoxia (medical) Peptide Fragments IκBα Cytokine Endocrinology chemistry Tumor necrosis factor alpha medicine.symptom Signal Transduction |
| Zdroj: | International Journal of Obesity. 36:986-992 |
| ISSN: | 1476-5497 0307-0565 |
| DOI: | 10.1038/ijo.2011.200 |
| Popis: | Obesity is associated with adipose tissue hypoxia, and is thought to be linked to the chronic low-grade inflammation of adipose tissue, although the precise mechanism has remained unclear. In this study, we investigated the effect of a prominent hypoxia on human primary adipocyte secretion and tumor necrosis factor alpha (TNFα)-induced nuclear factor-κB (NF-κB) signaling.Using cytokine array and ELISA analysis, we compared the secretion patterns of normoxic and hypoxic (1% O(2)) adipocytes and observed various alterations in adipokine release. We could reproduce known alterations like an induction of interleukin (IL)-6, vascular endothelial growth factor, leptin and a reduction in adiponectin release under hypoxia. Interestingly, we observed a significant reduction in the secretion of macrophage chemotactic protein (MCP)-1 and other NF-κB-related genes, such as growth-regulated oncogene-α, eotaxin and soluble TNF-Receptor1 (TNF-R1) under hypoxia. TNFα stimulation of hypoxic adipocytes resulted in a significantly reduced phosphorylation of NF-κB and its inhibitor IκBα compared with normoxic cells. Furthermore, chronic treatment of hypoxic adipocytes with TNFα resulted in an expected higher secretion of the chemokines MCP-1 and IL-8, but under hypoxia, the secretion level was substantially lower than that under normoxia. This reduction in protein release was accompanied by a reduced mRNA expression of MCP-1, whereas IL-8 mRNA expression was not altered. Additionally, we observed a significantly reduced expression of the TNF-receptor TNF-R1, possibly being one cause for the reduced responsiveness of hypoxic adipocytes towards TNFα stimulation.In conclusion, human primary adipocytes show a basal and TNFα-induced reduction of MCP-1 release under hypoxia. This effect may be due to a reduced expression of TNF-R1 and therefore attenuated TNFα-induced NF-κB signaling. These observations demonstrate a reduced responsiveness of hypoxic adipocytes towards inflammatory stimuli like TNFα, which may represent an adaptation process to maintain adipose tissue function under hypoxia and inflammatory conditions. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|