S100A8 inhibits PDGF-induced proliferation of airway smooth muscle cells dependent on the receptor for advanced glycation end-products.

BACKGROUND: Airway remodeling is a key feature of asthma, characterized by increased proliferation of airway smooth muscle cells (ASMCs). S100A8 is a calcium-binding protein with a potential to regulate cell proliferation. Here, the effect of exogenous S100A8 protein on the proliferation of ASMCs induced by platelet-derived growth factor (PDGF) and the underlying molecular mechanism was investigated. METHODS: Rat ASMCs were cultured with or without a neutralizing antibody to the receptor for advanced glycation end-products (RAGE), a potential receptor for S100A8 protein. Purified recombinant rat S100A8 protein was then added into the cultured cells, and the proliferation of ASMCs induced by PDGF was detected by colorimetric-based WST-8 assay and ampedance-based xCELLigence proliferation assay. The expression levels of RAGE in ASMCs were analyzed using western blotting assay. RESULTS: Results showed that exogenous S100A8 inhibited the PDGF-induced proliferation of rat ASMCs in a dose-dependent manner with the maximal effect at 1 µg/ml in vitro. Furthermore, when ASMCs was pre-treated with anti-RAGE neutralizing antibody, the inhibitory effect of S100A8 on PDGF-induced proliferation was significantly suppressed. In addition, neither the treatment with S100A8 or PDGF alone nor the pre-treatment with rS100A8 followed by PDGF stimulation affected the expression levels of RAGE. CONCLUSIONS: Our study demonstrated that S100A8 inhibits PDGF-induced ASMCs proliferation in a manner dependent on membrane receptor RAGE.

S100A8 protein attenuates airway hyperresponsiveness by suppressing the contraction of airway smooth muscle.

Airway hyperresponsiveness (AHR) is a major clinical problem in allergic asthma mainly caused by the hypercontractility of airway smooth muscles (ASM). S100A8 is an important member of the S100 calcium-binding protein family with a potential to regulate cell contractility. Here, we analyze the potential of S100A8 to regulate allergen-induced AHR and ASM contraction. Treatment with recombinant S100A8 (rS100A8) diminished airway hyperresponsiveness in OVA-sensitized rats. ASM contraction assays showed that rS100A8 reduced hypercontractility in both isolated tracheal rings and primary ASM cells treated by acetylcholine. rS100A8 markedly rescued the phosphorylation level of myosin light chain induced by acetylcholine in ASM cells. These results show that rS100A8 plays a protective role in regulating AHR in asthma by inhibiting ASM contraction. These results support S100A8 as a novel therapeutic target to control ASM contraction in asthma.

Serum from asthmatic rat treated with acupuncture inhibits acetylcholine- induced contractile responses of airway smooth muscle cells.

OBJECTIVE: To investigate the influence of serum from asthmatic rat treated with acupuncture (acupuncture serum) on the contractile responses of airway smooth muscle cells (ASMCs). METHODS: OVA-induced asthmatic rats were subject to acupuncture treatment at the points of Dazhui (GV 14), Fengmen (BL 12), and Feishu (BL 13). The resulting serum was collected, as well as serum from normal animals. Contraction of ASMCs was induced with 10 µM acetylcholine (Ach), and acupuncture serum or normal serum was supplemented 15 min later. The effects of the sera on the changes in cell length, width, and surface area were monitored in real time via a live cell imaging system. RESULTS: The contraction rates of ASMCs 15 min and 30 min after Ach stimulation reached 38.2% ± 3.8% and 49.7% ± 4.6%, both of which were significantly higher than unstimulated control cells (P < 0.01). Acupuncture serum at the 1:100 dosage reduced the contraction rate of ASMCs from 40.1% ± 5.1% to 17.6% ± 6.5% (P < 0.01). Thus, the treatment significantly inhibited the Ach-induced contractile responses of ASMCs and yielded a relaxation efficiency of 58%, which was greater than the effects obtained with a 1:250 dosage. Treatment with acupuncture serum at 1:500 dosage or normal serum displayed no clear effect of suppressing Ach-induced contraction of ASMCs. CONCLUSION: Our data suggest that acupuncture serum has the effect of inhibiting Ach-induced contraction of ASMCs, thereby promoting relaxation of the cells.

S100A8 inhibits PDGF-induced proliferation of airway smooth muscle cells dependent on the receptor for advanced glycation end-products

BACKGROUND: Airway remodeling is a key feature of asthma, characterized by increased proliferation of airway smooth muscle cells (ASMCs). S100A8 is a calcium-binding protein with a potential to regulate cell proliferation. Here, the effect of exogenous S100A8 protein on the proliferation of ASMCs induced by platelet-derived growth factor (PDGF) and the underlying molecular mechanism was investigated. METHODS: Rat ASMCs were cultured with or without a neutralizing antibody to the receptor for advanced glycation end-products (RAGE), a potential receptor for S100A8 protein. Purified recombinant rat S100A8 protein was then added into the cultured cells, and the proliferation of ASMCs induced by PDGF was detected by colorimetric-based WST-8 assay and ampedance-based xCELLigence proliferation assay. The expression levels of RAGE in ASMCs were analyzed using western blotting assay. RESULTS: Results showed that exogenous S100A8 inhibited the PDGF-induced proliferation of rat ASMCs in a dose- dependent manner with the maximal effect at 1 µg/ml in vitro. Furthermore, when ASMCs was pre-treated with anti-RAGE neutralizing antibody, the inhibitory effect of S100A8 on PDGF-induced proliferation was significantly suppressed. In addition, neither the treatment with S100A8 or PDGF alone nor the pre-treatment with rS100A8 followed by PDGF stimulation affected the expression levels of RAGE. CONCLUSIONS: Our study demonstrated that S100A8 inhibits PDGF-induced ASMCs proliferation in a manner dependent on membrane receptor RAGE.

Exogenous S100A8 protein inhibits PDGF-induced migration of airway smooth muscle cells in a RAGE-dependent manner.

S100A8 is an important member of the S100 protein family, which is involved in intracellular and extracellular regulatory activities. We previously reported that the S100A8 protein was differentially expressed in the asthmatic respiratory tracts. To understand the potential role of S100A8 in asthma, we investigated the effect of recombinant S100A8 protein on the platelet-derived growth factor (PDGF)-induced migration of airway smooth muscle cells (ASMCs) and the underlying molecular mechanism by using multiple methods, such as impedance-based xCELLigence migration assay, transwell migration assays and wound-healing assays. We found that exogenous S100A8 protein significantly inhibited PDGF-induced ASMC migration. Furthermore, the migration inhibition effect of S100A8 was blocked by neutralizing antibody against the receptor for advanced glycation end-products (RAGE), a potential receptor for the S100A8 protein. These findings provide direct evidence that exogenous S100A8 protein inhibits the PDGF-induced migration of ASMCs through the membrane receptor RAGE. Our study highlights a novel role of S100A8 as a potential means of counteracting airway remodeling in chronic airway diseases.

Non-specific physiological background effects of acupuncture revealed by proteomic analysis in normal rats.

BACKGROUND: The total effects of adequate real acupuncture treatment consist of pathologic-specific and non-specific physiological effects. The latter may be the fundamental component of the therapeutic effects of acupuncture. This study investigated the physiological background effects of acupuncture in normal rats treated with acupuncture. METHODS: Manual acupuncture was performed on normal rats at experienced acupoints, GV14 (Dazhui), BL12 (Fengmen) and BL13 (Feishu), once every other day for two weeks. The proteomic profile of rat lung tissue was examined using 2-DE/MS-based proteomic techniques. Gene Ontology (GO) enrichment and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway were analyzed for differentially expressed proteins using the WebGestalt toolkit. RESULTS: In total, 25 differentially expressed protein spots were detected in the 2-DE gels. Among these spots, 24 corresponded to 20 unique proteins that were successfully identified using mass spectrometry. Subsequent GO and KEGG pathway analyses demonstrated that these altered proteins were mainly involved in biological processes, such as 'protein stabilization', 'glycolysis/gluconeogenesis' and 'response to stimulus'. CONCLUSIONS: Our study indicated the non-specific background effects of acupuncture at acupoints GV14, BL12 and BL13 likely maintained internal homeostasis via regulation of the local stimulus response, energy metabolism, and biomolecule function balance, which may be important contributors to the therapeutic effects of acupuncture.