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Reduced cardiac hypertrophy in toll-like receptor 4-deficient mice following pressure overload.

Abstract：

OBJECTIVE:We have previously demonstrated that nuclear factor kappa B (NFkappaB) activation is needed for the development of cardiac hypertrophy in vivo. NFkappaB is a downstream transcription factor in the Toll-like receptor (TLR)-mediated signaling pathway; therefore, we investigated a role of TLR4 in cardiac hypertrophy in vivo. METHODS:TLR4-deficient mice (C.C3H-Tlr4(lps-d), n = 6), wild-type (WT) genetic background mice (BALB/c, n = 6), TLR4-deleted strain (C57BL/10ScCr, n = 8), and WT controls (C57BL/10ScSn, n = 8) were subjected to aortic banding for 2 weeks. Age-matched surgically operated mice served as controls. In a separate experiment, rapamycin (2 mg/kg, daily) was administered to TLR4-deficient mice and WT mice immediately following aortic banding. The ratio of heart weight/body weight (HW/BW) was calculated, and cardiac myocyte size was examined by FITC-labeled wheat germ agglutinin staining of membranes. NFkappaB binding activity and the levels of phospho-p70S6K in the myocardium were also examined. RESULTS:Aortic banding significantly increased the ratio of HW/BW by 33.9% (0.601 +/- 0.026 vs. 0.449 +/- 0.004) and cell size by 68.4% in WT mice and by 10.00% (0.543 +/- 0.011 vs. 0.495 +/- 0.005) and by 11.8% in TLR4-deficient mice, respectively, compared with respective sham controls. NFkappaB binding activity and phospho-p70S6K levels were increased by 182.6% and 115.2% in aortic-banded WT mice and by 78.0% and 162.0% in aortic-banded TLR4-deficient mice compared with respective sham controls. In rapamycin-treated aortic-banded mice, the ratio of HW/BW was increased by 18.0% in WT mice and by 3.5% in TLR4-deficient mice compared with respective sham controls. CONCLUSION:Our results demonstrate that TLR4 is a novel receptor contributing to the development of cardiac hypertrophy in vivo and that both the TLR4-mediated pathway and PI3K/Akt/mTOR signaling are involved in the development of cardiac hypertrophy in vivo.

journal_name

Cardiovasc Res

journal_title

Cardiovascular research

authors

Ha T,Li Y,Hua F,Ma J,Gao X,Kelley J,Zhao A,Haddad GE,Williams DL,William Browder I,Kao RL,Li C

doi

10.1016/j.cardiores.2005.05.025

subject

Has Abstract

pub_date

2005-11-01 00:00:00

pages

224-34

issue

eissn

0008-6363

issn

1755-3245

pii

S0008-6363(05)00279-8

journal_volume

pub_type

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Reduced cardiac hypertrophy in toll-like receptor 4-deficient mice following pressure overload.