Toll like receptor 4- a potential transmembrane receptor contributes to the cardiac remodeling of hypertension

AIM: To observe the expression of Toll like receptor 4 (TLR4) in the left ventricle of Goldblatt rats and to explore the role and mechanism of TLR4 in left ventricular remodeling of hypertension.METHODS: Goldblatt model of Two-kidney,one-clip(2K1C) renovascular hypertension was induced in twenty-five rats(H group),and twenty rats served the sham-operated group(sham group).The tail cuff blood pressure was detected every week and echocardiogram was observed every other week.After eight weeks of operation,the rats were killed and the samples of the left ventricle were collected.The concentration of AngⅡ in left ventricle was assessed by radioimmunoassay.Western blotting and RT-PCR were used to exam the mRNA and protein expression of TLR4 in the left ventricle.Immunohistochemistry was adopted to exam the location of TLR4 in the myocardium.RESULTS: TLR4 mRNA and protein expression were consistently upregulated in the left ventricle of H group compared with sham group.In H group,predominantly sarcolemmal staining was observed,especially focal areas of intense TLR4 staining were found in juxtaposed regions of two or more adjacent myocytes;However,in sham group,TLR4 expression was diffuse and presumably cytoplasmic.Considerable correlation was found between blood pressure,MESS,LVMI,RWT,the concentration of AngⅡ in left ventricle and the protein expression of TLR4 in myocytes.CONCLUSION: During the development of left ventricular remodeling of Goldblatt rats,expression of TLR4 increases significantly.Enhanced expression of TLR4 locates in the sarcolemma,especially in juxtaposed regions of two or more adjacent myocytes.These indicate that TLR4 transmembrane receptor which is closely relative with inflammation and immunity probably contributes to the development of ventricular remodeling.