Tracheal Smooth Muscle Cells Stimulated by Stem Cell Factor-c-Kit Coordinate the Production of Transforming Growth Factor-ß1 and Fibroblast Growth Factor-2 Mediated by Chemokine (C-C Motif) Ligand 3.

The aim of this study was to evaluate the mechanism involved in the stem cell factor (SCF)-induced production of fibroblast growth factor-2 (FGF-2), transforming growth factor-ß1 (TGF-ß1), and chemokine (C-C motif) ligand 3 (CCL3) in tracheal smooth muscle cells (tSMCs) and the signaling pathway involved in the process. tSMC primary cultures were stimulated with SCF and evaluated at 24 h. Cells treated with specific antibodies did not show any immunolabeling for cytokeratin or fibroblast activation protein, but were positive for α-smooth muscle actin, indicating the purity of the primary cell line. Western blot analysis showed constitutive phosphorylation of c-Kit, as well as increased total protein and phosphorylated c-Kit levels in tSMCs after SCF stimulation. Flow cytometry analysis also showed an increase in cell-surface c-Kit expression in the presence of SCF. SCF induced TGF-ß mRNA expression in tSMCs, as well as the production of TGF-ß1, CCL3, and FGF-2. Pretreatment with anti-CCL3 antibody blocked TGF-ß1 expression and partially inhibited FGF-2 production. On the other hand, anti-c-Kit antibody blocked TGF-ß1 expression and FGF-2 production. Thus, TGF-ß1 and FGF-2 production were mediated by CCL3 production through c-Kit. Pretreatment with mitogen-activated protein kinase kinase 1, p38, and Jun N-terminal kinase inhibitors showed that the effects mediated by SCF were involved with the modulation of mitogen-activated protein kinase (MAPK) pathways. Development of inhibitors targeting CCL3 through MAPK activation could thus be an attractive strategy to inhibit tSMC activation during asthma.

Stem cell factor estimula células da musculatura lisa da traqueia a produzir TGF-B, FGF-2 e CCL3/MIP-1a / Stem cell factor stimulates tracheal smooth muscle cells to produce TGF-B, FGF-2 and CCL3/MIP-1a

O objetivo deste estudo foi avaliar o mecanismo envolvido na produção de TGF-β, FGF-2 e CCL3/MIP-1α induzida por Stem cell factor (SCF) em células da musculatura lisa de traqueia (CMLT) e as vias de transdução de sinalização ativadas. Traqueias de camundongos normais foram coletadas, fragmentadas e colocadas em garrafas contendo meio de cultura DMEM com 10% de Soro Fetal Bovino. CMLT foram estimuladas com SCF (1, 10 and 100 ng/mL) e avaliadas após 1, 6 e 24 horas. Características fenotípicas das CMLT foram analisadas por imunofluorescência para α-actina de músculo liso (α-AML), α-citoqueratina e α-proteína de ativação de fibroblastos (α-FAP). Ativação de c-kit em CMLT estimuladas por SCF foi avaliada por citometria de fluxo. A expressão de RNAm para TGF-β foi observada pela reação de polimerase em cadeia-transcriptase reversa (RT-PCR) e a produção da proteína, por ensaio de imunoabsorção enzimática (ELISA). A produção de FGF-2 foi avaliada por immunoblot e a produção de CCL3/MIP-1α por ELISA. Em outro conjunto de experimentos, CMLT foram pré-tratadas com inibidores de MAPK p42/44(PD 98059 [PD]), p38(SB 202190[SB]), e JNK (SP 600125 [SP]) por 30 minutos seguidos de estimulação com SCF (10 ng/mL) por 24 horas. Células pré-tratadas com anticorpos específicos não revelaram qualquer marcação para citoqueratina nem para α-FAP, contudo, ocorrendo a marcação para α-AML, indicando a pureza da linhagem celular primária. SCF induziu a expressão de receptores c-kit em CMLT. CMLT estimuladas por 10 ng/mL de SCF expressaram TGF-β mRNA e produziram TGF- β proteína, FGF-2 e CCL3/MIP-1α após 24 horas. O pré-tratamento com SB, PD e SP inibiu estas produções. Estas produções foram mediadas pela ativação das vias p42/44, p38, e JNK. CMLT parecem ser importantes células residentes envolvidas na ativação e reparo tecidual, visto que são capazes de produzir fatores de crescimentos e quimiocinas, adicionando novas informações sobre o papel da musculatura lisa de traqueia na...

The aim of this study was to evaluate the mechanism involved in SCF-induced TGF-β, FGF-2 and CCL3/MIP-1α production in tracheal smooth muscle cells (tSMC) and the activated signaling transduction pathway. Normal mouse tracheas were collected, fragmented and placed in bottles containing the culture medium DMEM with 10% Fetal Bovine Serum. tSMC primary cultures were stimulated with SCF (1, 10 and 100 ng/mL) and evaluated at 1, 6 and 24 hours. The phenotypic characteristic of tSMC in primary culture was analyzed using immunofluorescence staining for α-smooth muscle actin (α-SMA), α-cytokeratin and α-Fibroblast Activation Protein (α-FAP). c-Kit activation in SCF-stimulated tSMC was evaluated by flow cytometric. The TGF-β mRNA expression was observed by reverse-transcriptase polymerase chain reaction (RT-PCR) and protein production by enzyme-linked immunosorbent assay (ELISA). FGF-2 production was evaluated by immunoblot and CCL3/MIP-1α production by ELISA. In other set of experiment, tSMC were pretreated p42/44 inhibitor (PD 98059 [PD]), p38 inhibitor (SB 202190[SB]), or JNK inhibitor (SP 600125 [SP]) for 30 minutes followed by stimulation with SCF (10 ng/mL) for 24 hour. Cells treated with specific antibodies, showing neither labeling for cytokeratin nor either FAP, however, labeling for α-SMA indicating purity of the primary cell line. SCF induces c-Kit expression on tSMC. SCF-stimulated tSMC express TGF-β mRNA expression and FGF-2 and CCL3/MIP-1α production at 10 ng/mL after 24 hours. SB, PD and SP pre-treatment inhibited these productions. These productions were mediated by activation pathways p42/44, p38, and JNK. tSMC seems to be important resident cells involved in the cell activation and tissue repair, since they are capable of producing growth factors and chemokines and added new information about the role of tracheal smooth muscle cells in the allergic inflammation...