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β 1 ‐adrenergic receptor autoantibodies from heart failure patients enhanced TNF‐α secretion in RAW264.7 macrophages in a largely PKA‐dependent fashion
Author(s) -
Du Yunhui,
Yan Li,
Du Hongwei,
Wang Li,
Ding Fan,
Quan Lin,
Cheng Xiuli,
Song Kai,
Liu Huirong
Publication year - 2012
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.24198
Subject(s) - secretion , heart failure , receptor , extracellular , metoprolol , western blot , medicine , endocrinology , adrenergic receptor , catecholamine , adrenergic , cell culture , autoantibody , antagonist , tumor necrosis factor alpha , biology , immunology , antibody , microbiology and biotechnology , biochemistry , genetics , gene
Autoantibodies against the second extracellular loop of β 1 ‐adrenergic receptor (β 1 ‐AA) not only contribute to increased susceptibility to heart failure, but also play a causative role in myocardial remodeling through their catecholamine‐like effects via binding with the β 1 ‐adrenergic receptor. The current study was designed to determine whether β 1 ‐AA isolated from the sera of heart failure patients could cause TNF‐α secretion from the murine macrophage‐like cell line RAW264.7. Blood samples were collected from 40 patients who had suffered heart failure, as well as from 40 healthy subjects. The titer of β 1 ‐AA and the level of TNF‐α were detected using ELISA. The effect of β 1 ‐AA on murine macrophage‐like cell line RAW264.7 proliferation was detected by CCK‐8 kits and CFSE assay. Western blot assay was used to analyze the expression of phospho‐VASP. β 1 ‐AA appeared more frequently in patients with heart failure than in healthy subjects. The β 1 ‐AA isolated from heart failure patients promoted an increase of TNF‐α levels, which could be completely blocked by the selective β 1 ‐adrenergic receptor antagonist metoprolol and the second extracellular loop of β 1 ‐adrenergic receptor (β 1 ‐AR‐EC II ), but only partially inhibited by PKA inhibitor H89. Furthermore, the β 1 ‐AA could enhance the proliferation of RAW264.7 cells in vitro. Meanwhile, the expression of phospho‐VASP was markedly increased in the presence of β 1 ‐AA. These results demonstrate for the first time that the β 1 ‐AA isolated from heart failure patients could bind with β 1 ‐AR on the surface of RAW264.7 cells, causing the release of TNF‐α largely in a PKA‐dependent fashion. J. Cell. Biochem. 113: 3218–3228, 2012. © 2012 Wiley Periodicals, Inc.