BACKGROUNDRepeated attacks of bronchial asthma lead to different degrees of airway remodeling, the mechanism of which is not yet clear. Some evidences indicate that it is related to the excessive expression of some growth promotion factors. Angiotensin II is a polypeptide that may be involved in airway remodeling. To evaluate its role in airway remodeling in asthma, we observed the effects of an angiotensin II type 1 receptor antagonist (valsartan) on the expression of collagen III, collagen V, and transforming growth factor beta1 (TGF-beta1) mRNA and protein in the airway walls of sensitized rats.

METHODSForty Wistar rats were randomly divided into 5 groups: control group, sensitized group, and valsartan groups 1, 2, and 3. The rats in the sensitized group and in valsartan groups 1, 2, and 3 were sensitized and challenged with ovalbumin. Rats in control group were sensitized and challenged with 0.9% NaCl. Rats from valsartan groups 1, 2, and 3 were drenched with valsartan (10 microg, 20 microg, or 30 microg, respectively) at the time of the ovalbumin challenges. The expression of collagen III, collagen V, and TGF-beta1 protein were detected using immunohistochemical method in combination with image analysis methods. The expression of TGF-beta1 mRNA was detected by in situ hybridization.

RESULTSThe expression in the airways of collagen III and collagen V was significantly higher in rats from the sensitized group (7.73 +/- 0.81, 1.34 +/- 0.28) and from valsartan groups 1, 2, and 3 (5.73 +/- 0.64, 1.13 +/- 0.15; 4.96 +/- 0.51, 0.98 +/- 0.08; 4.43 +/- 0.35, 0.93 +/- 0.06, respectively) than those in the control group (2.65 +/- 0.38, 0.67 +/- 0.08, P < 0.05). In addition, collagen levels were significantly lower in valsartan groups 1, 2, and 3 than those from the sensitized group (P < 0.05). The expression of TGF-beta1 mRNA and protein in the airways was significantly higher in rats from the sensitized group (20.49% +/- 3.46%, 29.73% +/- 3.25%) and from valsartan groups 1, 2, and 3 (16.47% +/- 1.94%, 19.41% +/- 1.87%; 14.38% +/- 1.58%, 18.29% +/- 1.43%; 12.96% +/- 1.73%, 18.63% +/- 1.11%, respectively) than that from the control group (7.84% +/- 1.61%, 5.63% +/- 1.07%, P < 0.05). TGF-beta1 mRNA and protein levels were significantly lower in valsartan groups 1, 2, and 3 than that in the sensitized group (P < 0.05).

CONCLUSIONSAngiotensin II receptor antagonist valsartan can suppress synthesis of collagen III and collagen V by downregulating TGF-beta1 mRNA and protein expression. Valsartan can decrease airway remodeling and could play a role in asthma therapy.

Angiotensin Receptor Antagonists ; Animals ; Asthma ; physiopathology ; Bronchi ; metabolism ; Collagen Type III ; analysis ; Collagen Type V ; analysis ; Immunization ; Male ; Ovalbumin ; RNA, Messenger ; analysis ; Random Allocation ; Rats ; Rats, Wistar ; Tetrazoles ; pharmacology ; Transforming Growth Factor beta ; analysis ; Valine ; analogs & derivatives ; pharmacology ; Valsartan

OBJECTIVEBronchial asthma is a chronic inflammatory disorder. Long-term inflammation leads to varying degrees of structural changes in the airway wall known as airway reconstruction or remodeling. These structural changes are found in the airways of most patients with prolonged disease. After remodeling, the airway walls show the submucous membrane becomes thick with collagen deposition, and the smooth muscle cells show hyperplasia and hypertrophy. Smooth muscle cells are a vital component of the airway wall, and a major effector cell involved in the course of bronchial contraction. Smooth muscle cell hyperplasia and hypertrophy are important pathological changes in airway remodeling. This study investigated the expression of markers of human airway smooth muscle cells (ASMCs) phenotypic change, which were matrix Gla protein (MGP) and major fibrosis proteins, after in vitro treatment with transforming growth factor-beta(1) (TGF-beta(1)).

METHODSHuman ASMCs were subjected to primary culture in vitro. Ten groups of cells were treated with 100 microg/ml of TGF-beta(1), while the cells in the control groups were treated with 10% fetal bovine serum. After being cultured for 7 d, the cells of both groups were harvested. MGP mRNA expression was detected by RT-PCR. Protein levels of collagen I, III and V were determined by Western blot analysis.

RESULTSTreated with TGF-beta(1), airway smooth muscle cells expressed MGP mRNA greater than controls [(62.3 +/- 13.1)% vs (27.4 +/- 11.4)%, P < 0.01]. Also, airway smooth muscle cells stimulated by TGF-beta(1) produced more collagen I, III and V than the control group (P < 0.01).

CONCLUSIONSTGF-beta(1) induced expression of collagen III and V, which are early markers of the switch from a contractile to a synthetic phenotype in ASMCs. This induction is an indication that ASMCs have the potential to make this switch and that TGF-beta(1) is involved in airway remodeling.

Biomarkers ; metabolism ; Blotting, Western ; Bronchi ; cytology ; Calcium-Binding Proteins ; genetics ; metabolism ; Cells, Cultured ; Collagen Type I ; metabolism ; Collagen Type III ; metabolism ; Collagen Type V ; metabolism ; Extracellular Matrix Proteins ; genetics ; metabolism ; Humans ; Myocytes, Smooth Muscle ; cytology ; drug effects ; metabolism ; RNA, Messenger ; drug effects ; Reverse Transcriptase Polymerase Chain Reaction ; Transforming Growth Factor beta1 ; pharmacology

Periodontal ligament(PDL) cells have been known as playing an important roles in periodontal regeneration and gingival fibroblasts are also important to periodontal regeneration by forming connective tissue attachment. There were rare studies about the gene expression patterns of PDL cells and gingival fibroblasts, therefore in this study, we tried cDNA microarray-based gene expression monitoring to explain the functional differences of PDL cells and gingival fibroblasts in vivo and to confirm the characteristics of PDL cells. Total RNA were extracted from PDL cells and gingival fibroblasts of same person and same passages, and mRNA were isolated from the total RNA using Oligotex mRNA midi kit(Qiagen) and then fluorescent cDNA probe were prepared. And microarray hybridization were performed. The gene expression patterns of PDL cells and gingival fibroblasts were quite different. About 400 genes were expressed more highly in the PDL cells than gingival fibroblasts and about 300 genes were more highly expressed in the gingival fibroblasts than PDL cells. Compared growth factor- and growth factor receptor-related gene expression patterns of PDL cells with gingival fibroblasts, IGF-2, IGF-2 associated protein, nerve growth factor, placental bone morphogenic protein, neuron-specific growth- associated protein, FGF receptor, EGF receptor-related gene and PDGF receptor were more highly expressed in the PDL cells than gingival fibroblasts. The results of collagen gene expression patterns showed that collagen type I, type III, type VI and type VII were more highly expressed in the PDL cells than gingival fibroblasts, and in the gingival fibroblasts collagen type V, XII were more highly expressed than PDL cells. The results of osteoblast-related gene expression patterns showed that osteoblast specific cysteine-rich protein were more highly expressed in the PDL cells than gingival fibroblasts. The results of cytoskeletal proteins gene expression patterns showed that alpha-smooth muscle actin, actin binding protein, smooth muscle myosin heavy chain homolog and myosin light chain were more highly expressed in the PDL cells than gingival fibrobalsts, and beta-actin, actin-capping protein(beta subunit), actin- related protein Arp3(ARP) and myosin class I(myh-1c) were more highly expressed in the gingival fibroblasts than PDL cells. Osteoprotegerin/osteoclastogenesis inhibitory factor(OPG/OCIF) was more highly expressed in the PDL cells than gingival fibroblasts. According to the results of this study, PDL cells and gingival fibroblasts were quite different gene expression patterns though they are the fibroblast which have similar shape. Therefore PDL cells & gingival fibroblasts are heterogeneous populations which represent distinct characteristics. If more studies about genes that were differently expressed in each PDL cells & gingival fibroblasts would be performed in the future, it would be expected that the characteristics of PDL cells would be more clear.
Actins ; Carrier Proteins ; Collagen ; Collagen Type I ; Collagen Type V ; Connective Tissue ; Cytoskeletal Proteins ; DNA, Complementary* ; Epidermal Growth Factor ; Fibroblasts* ; Gene Expression Profiling ; Gene Expression* ; Humans ; Insulin-Like Growth Factor II ; Muscle, Smooth ; Myosin Heavy Chains ; Myosin Light Chains ; Myosins ; Nerve Growth Factor ; Oligonucleotide Array Sequence Analysis* ; Osteoblasts ; Periodontal Ligament* ; Receptors, Fibroblast Growth Factor ; Receptors, Platelet-Derived Growth Factor ; Regeneration ; RNA ; RNA, Messenger

This study investigated the effects of SIRT1 gene knock-out on osteoarthritis in mice, and the possible roles of SREBP2 protein and the PI3K/AKT signaling pathway in the effects. Mice were randomly divided into a normal group and a SIRT1 gene knock-out group (6 mice in each group). In these groups, one side of the knee anterior cruciate ligament was traversed, and the ipsilateral medial meniscus was cut to establish an osteoarthritis model of knee joint. The countralateral synovial bursa was cut out, serving as controls. The knee joint specimens were then divided into four groups: SIRT1control group (group A, n=6); SIRT1osteoarthritis group (group B, n=6); SIRT1control group (group C, n=6); SIRT1osteoarthritis group (group D, n=6). HE staining, Masson staining, Safranin O-Fast Green staining and Van Gieson staining were used to observe the morphological changes in the articular cartilage of the knee. Immunohistochemical staining was employed to detect the expression of SIRT1, SREBP2, VEGF, AKT, HMGCR and type II collagen proteins. SA-β-gal staining was utilized to evaluate chondrocyte aging. The results showed clear knee joint cartilage destruction and degeneration in the SIRT1osteoarthritis group. The tidal line was twisted and displaced anteriorly. Type II collagen was destroyed and distributed unevenly. Compared with the SIRT1osteoarthritis group and SIRT1control group, SIRT1 protein expression was not obviously changed in the SIRT1osteoarthritis group (P>0.05), while the expression levels of the SREBP2, VEGF and HMGCR proteins were significantly increased (P<0.05) and the levels of AKT and type II collagen proteins were significantly decreased (P<0.05). SIRT1 gene knock-out may aggravate cartilage degeneration in osteoarthritis by activating the SREBP2 protein-mediated PI3K/AKT signalling pathway, suggesting that SIRT1 gene may play a protective role against osteoarthritis.
Animals ; Cartilage ; pathology ; Chondrocytes ; metabolism ; Collagen Type II ; metabolism ; Disease Models, Animal ; Humans ; Knee Joint ; metabolism ; pathology ; Mice ; Mice, Knockout ; Oncogene Protein v-akt ; genetics ; Osteoarthritis ; genetics ; pathology ; Phosphatidylinositol 3-Kinases ; genetics ; Signal Transduction ; genetics ; Sirtuin 1 ; genetics ; Sterol Regulatory Element Binding Protein 2 ; biosynthesis ; genetics ; Vascular Endothelial Growth Factor A ; biosynthesis