Differences in Cultured Cardiac Fibroblast Populations Isolated From SHR and Wky Rats

Abstract

1. The mechanisms whereby angiotensin converting enzyme inhibitors reverse cardiac remodelling appear to involve angiotensin and/or bradykinin receptors. Previously we reported that cultured rat cardiac fibroblasts express angiotensin I1 (AII) receptors. In the present study we compared A11 receptor binding, gene expression of angiotensinogen and the AII, Subtype 1A (ATlA) receptor, as well as morphological changes induced by selected hormonal treatments in cultured fibroblasts derived from SHRLJ or WKYLJ rats.2. Fibroblasts were isolated from adult rat left ventricle by either collagenase B or collagenase P digestion. Collagenase B yielded cell preparations from SHRLJ which grew slower than cells from WKYLJ rats and expressed nearly two-fold fewer A11 receptors (compared to WKYLJ) while collagenase P yielded SHRLJ cells with similar binding and growth properties to WKYLJ. A good correlation was observed between receptor binding and A11 receptor, type 1A (ATlA) mRNA concentrations. In the presence of steroids collagenase B cells showed a higher tendency to transform towards a preadipocyte cell type, estimated by the formation of lipid containing vacuoles/ cell, while collagenase P cells, mainly the SHRLJ type, start to differentiate toward a myofibroblast-like cell type in the presence of AII, as calculated by the expression of a-smooth muscle actin.3. From the results obtained in this study it is evident that a subset of fibroblasts can be isolated from the SHRLJ heart using collagenase B or P which differ in growth rates, A11 receptor binding, ATlA and angiotensinogen mRNA levels, morphology and steroid responsiveness when compared to fibroblasts isolated from cardiac WKYLJ tissue.

Angiotensin-TGF-β1 Crosstalk in Human Idiopathic Pulmonary Fibrosis:Autocrine Mechanisms in Myofibroblasts and Macrophages

“…The black arrows denote AGT/ANGI labeling in the same microfoci denoted in Panel A as -SMA-positive by the white arrows. This colocalization of -SMA and AGT/ANGI labeling is consistent with the concept that myofibroblasts in the IPF lung in situ constitutively synthesize AGT as they do in other organs [17] and in culture after isolation [13][14][15][16]. In Fig.…”

“…In light of the commonality of AGT expression by myofibroblasts from a variety of tissues [12][13][14][15][16][17] and the known profibrotic roles of ANGII [18][19][20][21], the definition of the factor(s) which maintain increased basal AGT expression by myofibroblasts is a high priority. TGF-1 is considered one of the most potent stimuli for normal fibroblasts to undergo the transition to myofibroblasts [26].…”

“…Constitutive expression of AGT by myofibroblasts has been demonstrated in vitro after isolation of these cells from the fibrosing rat heart [12][13][14], from the cirrhotic human liver [15], or from the lungs of patients with Idiopathic Pulmonary Fibrosis [16]. Myofibroblasts also synthesize AGT and ANGII in vivo in the fibrosing mouse kidney [17].…”

Transforming growth factor-β1 induces angiotensin-converting enzyme synthesis in rat cardiac fibroblasts during their differentiation to myofibroblasts

“…Among fibroblast-like cells, only myofibroblasts contain filaments of α-SMA, which is a marker of this cell phenotype. 19,[73][74][75][76][77][78][79][80][81][82][83][84] There is, however, some controversy in the literature about the presence of α-SMA, i.e. Heterogeneity of fibroblast cultures, even from one anatomical site, is well-known.…”

“…18 Therefore, the presence of α-SMA indicates that our fibroblast cultures were heterogeneous and contained myofibroblasts. 16,34,35,42,83 Actin is also absent in quiescent cultures incubated in the absence of serum and growth factors 34,42 and is present in growing cultures, incubated in the presence of serum, which always contains TGF-β 1 . 19,[73][74][75][76][77][78][79][80][81][82][83][84] There is, however, some controversy in the literature about the presence of α-SMA, i.e.…”