Effect of hepatocyte growth factor and transforming growth factor-β(1) on atrial fibroblasts fibrosis / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the effect of hepatocyte growth factor (HGF) and transforming growth factor-β(1) (TGFβ(1)) on the expression of α-smooth muscle actin (α-SMA) and collagen I in human atrial fibroblast in vitro, and to explore the possible molecular mechanism of atrial fibrosis in patients with atrial fibrillation (AF).</p><p><b>METHODS</b>Human atrial fibroblast, isolated from aseptic right atrial appendage tissues of 10 sinus rhythm (SR) and 10 chronic atrial fibrillation (CAF) patients, were cultured with HGF and TGFβ(1). mRNA expressions of collagen I and α-SMA were detected by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR), the protein expression of α-SMA was determined by immunofluorescence and Western blot.</p><p><b>RESULTS</b>(1) Compared with SR group, left atrium was significantly dilated in CAF group (t = 2.692, P < 0.05), the mRNA expression of collagen I and α-SMA of atrial fibroblasts were significantly upregulated (all P < 0.01), mRNA expression of collagen I was positively correlated with left atrial dimension (LAD) (r = 0.836, P = 0.014), AF duration (r = 0.739, P = 0.045) and α-SMA mRNA level (r = 0.886, P = 0.012). (2) Compared with SR group, the expression of α-SMA protein in CAF atrial fibroblasts were significantly increased (P < 0.01). (3) TGFβ(1) further stimulated while HGF significantly attenuated the expression of collagen I and α-SMA in CAF atrial fibroblasts (all P < 0.01).</p><p><b>CONCLUSIONS</b>Increasing expression of collagen I and α-SMA in human atrial fibroblasts might promote atria remodeling leading to the development and sustaining of AF. HGF is involved in the negative regulation on the expression of α-SMA and collagen I.</p>

Relationship between atrial fibroblast proliferation/fibrosis and atrial fibrillation in patients with rheumatic heart disease / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the association between gene expressions of basic fibroblast growth factor (bFGF), smooth muscle alpha-actin (alpha-SMA) and proliferating cell nuclear antigen (PCNA) and atrial fibrosis in patients with atrial fibrillation (AF).</p><p><b>METHODS</b>The right atrial tissue samples were taken from 75 patients with rheumatic heart disease underwent heart valve replacement surgery (34 patients with sinus rhythm, 11 patients with paroxysmal AF and 30 patients with persistent AF) and stained with picrosirius red for quantitative analysis of collagen accumulation. The mRNA and protein levels of bFGF, alpha-SMA and PCNA were detected by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemical technique, respectively.</p><p><b>RESULTS</b>The percent volume fraction of collagen (CVF) was the highest in persistent AF group and the lowest in the sinus rhythm group (all P < 0.01). CVF significantly correlated with AF duration (r = 0.390, P = 0.010) and left atria (LA) dimension (r = 0.320, P = 0.005). The mRNA and protein levels of bFGF, alpha-SMA and PCNA were significantly higher in the persistent AF group than those in the paroxysmal AF group (all P < 0.05) and significantly higher in both AF groups than those in the sinus rhythm group (P < 0.05-0.01). The mRNA and protein levels of bFGF were positively correlated with CVF (r = 0.330, P = 0.004 and r = 0.292, P = 0.013, respectively), AF duration (r = 0.330, P = 0.005 and r = 0.299, P = 0.010, respectively) and left atrial dimension (r = 0.342, P = 0.003 and r = 0.285, P = 0.015, respectively).</p><p><b>CONCLUSION</b>The increased gene expressions of bFGF, alpha-SMA and PCNA in atrium during AF may contribute to atrial fibrosis by promoting fibroblast proliferation in AF patients.</p>

Changes in gelatinases expression and activity in human atria during atrial fibrillation / 中华心血管病杂志

<p><b>OBJECTIVE</b>To determine whether expression and activity of atrial gelatinases are altered in patients with atrial fibrillation (AF).</p><p><b>METHODS</b>The right atrial tissue samples were taken from 75 patients with rheumatic heart disease who underwent heart valve replacement surgery. 34 patients were in sinus rhythm, 11 patients had paroxysmal AF and 30 patients had persistent AF. The mRNA and protein level of MMP-2, MMP-9, TIMP-1, TIMP-2 were measured by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western-blotting analysis respectively. The activity of MMP-2 and MMP-9 was measured by zymographic analysis.</p><p><b>RESULTS</b>(1) The mRNA level of MMP-2 increased significantly in the persistent AF group followed by the paroxysmal AF group compared with the sinus rhythm group (P < 0.01, respectively). MMP-9 mRNA expression remained compatible within groups (P > 0.05). MMP-2 and MMP-9 protein expression was prominent in the persistent AF group compared with the sinus rhythm and paroxysmal AF groups (P < 0.01), the significant difference was also observed between the paroxysmal AF and sinus groups (P < 0.05). (2) TIMP-1 and TIMP-2 expression at mRNA and protein level were all down-regulated in the persistent AF group compared with the sinus rhythm group (P < 0.05), however, the trends of reduction did not reach statistical significance in the paroxysmal AF group (P > 0.05) except that of the mRNA level of TIMP-2 (P < 0.05). (3) The activity of MMP-2 and MMP-9 significantly increased in both paroxysmal AF and persistent AF groups compared with the sinus rhythm group (P < 0.05). The significant difference in MMP-9 was also observed between the persistent AF and paroxysmal AF groups (P < 0.01). (4) MMP-2 and MMP-9 expression at mRNA and protein level were positively correlated with left atrial dimension and AF duration (P < 0.05) and were negatively correlated with the mRNA and protein level of TIMP-2 and TIMP-1 respectively (P < 0.01).</p><p><b>CONCLUSIONS</b>The upregulation of MMP-2,9 gene expression and activity, along with the selective downregulation of TIMP-1,2 may have contributed to the atrial structural remodeling during AF through influencing collagen metabolism.</p>

Clinical on molecular basis of atrial fibrosis in patients with atrial fibrillation investigation / 中华心血管病杂志

<p><b>OBJECTIVE</b>To determine the molecular mechanisms involved in atrial fibrosis which occurs in patients with atrial fibrillation (AF) and to investigate their effects on the initiation and maintenance of AF.</p><p><b>METHODS</b>The right atrial tissue samples were taken from 73 patients with rheumatic heart disease who underwent heart valve replacement surgery. 34 patients had no history of AF (sinus rhythm group), 9 patients had paroxysmal AF and 30 patients had persistent AF. The mRNA content of collagen type I, collagen type III, MMP-2, TIMP-1, TIMP-2, TIMP-3 and TIMP-4 was measured by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and normalized to beta-actin or GAPDH.</p><p><b>RESULTS</b>Compared to sinus rhythm group, the mRNA of collagen type I and MMP-2 increased significantly in the persistent AF group (all, P < 0.01), followed by the paroxysmal AF group (all, P < 0.05). The mRNA of collagen type III was slightly higher in both AF groups than in the sinus rhythm group, but the differences were not statistically significant (P > 0.05). The mRNA of TIMP-1, TIMP-2 and TIMP-3 was down-regulated in the persistent AF group (all, P < 0.01, respectively), however, the trends of reduction did not reach statistical significance in the paroxysmal AF group (P > 0.05). The mRNA of TIMP-4 remained compatible in each group. The mRNA of collagen type I was significantly correlated with left atrial dimension (r = 0.336, P = 0.004) and AF duration (r = 0.339, P = 0.003). The mRNA of MMP-2 was significantly correlated with the mRNA of TIMP-2 (r = -0.326, P = 0.006), the mRNA of collagen type I (r = 0.322, P = 0.006), left atrial dimension (r = 0.300, P = 0.011) and AF duration (r = 0.300, P = 0.010).</p><p><b>CONCLUSION</b>The increased level of collagen type I associated with selective downregulation of TIMP-2 and upregulation of MMP-2 gene expression in atrium could be one of the molecular mechanisms of atrial fibrosis during atrial fibrillation, which correlates with the initiation and maintenance of AF.</p>

Relationship between collagen Ⅰ,MMP-2 and TIMP-2 gene expression and atrial fibrosis and fibrillation during heart failure in dogs / 中华老年医学杂志

Objective To study the relationship between Couagen Ⅰ,MMP-2,TIMP-2 gene expression and atrial fibrosis during heart failure(HF)in dog.Methods Fourteen dogs were used and randomized into HF induced by ventricular tachypacing and control group.Burst atrial pacing was used to induce atrial fibrillation(AF).And the mRNA and protein level of collagen Ⅰ,MMP-2 and TIMP-2 were detected by RT-PCR and immunohistochemical technique.Tissue samples were stained with Mallory trichrome.Results Left ventricular ejection fraction (LVEF) decreased from (67.4? 6.0)% to (29.2?7.8)%,the inducible rate of AF(7/7 vs 2/7) and sustained AF(5/7 vs 0/7) increased and duration of AF stabeatrial fibrillation(SAF) [(462.12?181.43)s vs(0.57?0.57) s] prolonged significantly in HF group.Atrial fibrous tissue content and atrial size of HF group were significantly greater than the controls dogs(268.8% in lefe atria and 190.3% in right atria).The mRNA and protein level of collagen Ⅰ(56.2% and 132.2% in lefe atria,37.4% and 78.0% in right atria)and MMP-2 (100.0% and 115.7% in lefe atria,65.7% and 96.8% in right atria) increased evidently in both lefe atria and right atria,TIMP-2 mRNA decreased 46.3% in lefe atria and had no change in right atria and that its protein had no change in both atrium,whereas the ratio of MMP-2/ TIMP-2 of mRNA and protein increased markedly in both lefe atria (285.3% and 148.8%)and right atria (106.1% and 134.7%)of HF group.SAF had a positive correlation with fibrosis and the gene level of collagen Ⅰ in lefe atria,the ratio of MMP-2/TIMP-2 had a positive correlation with fibrosis and collagen Ⅰ gene level in lefe atria during HF.Conclusions The changes of collagen Ⅰ,MMP-2 and TIMP-2 gene expression appear to be a molecular mechanism of AF, and the molecular remodeling of collagen Ⅰ induced by regulation unbalance of MMP-2/TIMP-2 appears to be an important mechanism of atrial fibrosis during HF.