Effect of TRPV1 Channel on Proliferation and Apoptosis of Airway Smooth Muscle Cells of Rats

Airway remodeling is an important pathological feature of asthma and the basis of severe asthma. Proliferation of airway smooth muscle cells （ASMCs） is a major contributor to airway remod- eling. As an important Ca2＋ channel, transient receptor potential vanilloid 1 （TRPV1） plays the key role in the cell pathological and physiological processes. This study investigated the expression and activity of TRPV1 channel, and further clarified the effect of TRPV1 channel on the ASMCs proliferation and apoptosis in order to provide the scientific basis to treat asthmatic airway remodeling in clinical practice Immunofluorescence staining and reverse transcription polymerase chain reaction （RT-PCR） were used to detect the expression of TRPVI in rat ASMCs. Intracellular Ca2＋ was detected using the single cell confocal fluorescence microscopy measurement loaded with Fluo-4/AM. The cell cycles were observed by flow cytometry. MTT assay and Hoechst 33258 staining were used to detect the proliferation and apoptosis of ASMCs in rats respectively. The data showed that： （1） TRPV1 channel was present in rat ASMCs. （2） TRPV1 channel agonist, capsaicin, increased the Ca2~ influx in a concentration-dependent manner （EC50=284.3＋58 nmol/L）. TRPV1 channel antagonist, capsazepine, inhibited Ca2＋ influx in rat ASMCs. （3） Capsaicin significantly increased the percentage of S＋G2M ASMCs and the absorbance of MTT assay. Capsazepine had the opposite effect. （4） Capsaicin significantly inhibited the apoptosis, whereas capsazepine had the opposite effect. These results suggest that TRPV1 is present and mediates Ca2＋ influx in rat ASMCs. TRPV1 activity stimulates proliferation of ASMCs in rats.

Effect of Cigarette Smoke Extract on the Role of Protein Kinase C in the Proliferation of Passively Sensitized Human Airway Smooth Muscle Cells

To investigate the effect of cigarette smoke extract (CSE) on the role of protein kinase C (PKC) in the proliferation of passively sensitized human airway smooth muscle cells (HASMCs). After synchronization of cultured HASMCs, they were divided into a group A and Group B. The group A was treated with normal human serum and served as controls and the group B was treated with the serum of asthma patients. The group A was further divided into group of A_1, A_2 and A_3 and the group B was sub-divided into the group of B_1, B_2, B_3, B_4 and B_5. No other agents were added to the group A_1 and B_1. The cells of group A_2 and B_2 were stimulated with 5 % CSE for 24 h. HASMCs from group A_3 and B_3 were treated with PKC agonist PMA (10 nmol/L) and CSE (5 %) for 24 h. PKC inhibitor Ro-31-8220 (5 μmol/L) was added to the HASMCs of group B_4 for 24 h. The cells from group B_5 were stimulated with Ro-31-8220 (5 μmol/L) and CSE (5 %) for 24 h. The proliferation of HASMCs isolated from group A and B was examined by cell cycle analysis, MTT colorimetric assay and 3H-TdR incorporation test. The expression of PKC-α in each group was observed by Western blotting and RT-PCR, respectively. The results showed that the percentage of S phase, absorbance (A) value, the rate of 3H-TdR incorporation, the ratios of A value of PKC-α mRNA and the A value of PKC-α protein in HASMCs from group B_1, B_2 and B_3 were significantly increased compared to those of group A_1, A_2 and A_3 correspondingly and respectively (P<0.01). The proliferation of HASMCs of group A_2 and B_2 stimulated with CSE and group A_3 and B_3 stimulated with CSE and PMA were also significantly enhanced when group A_1, A_2 and A_3 and group B_1, B_2 and B_3 compared to each other (P<0.05, P<0.01, respectively). The percentage of S phase, absorbency (A) value, 3H-TdR incorporation rate, the ratios of A value of PKC-α mRNA and the A value of PKC-α protein in HASMCs from group B_4 treated with Ro-31-8220 and group B_5 treated with CSE and Ro-31-8220 were significantly decreased as compared to those of group B_1 and B_2 correspondingly and respectively (P<0.05, P<0.01). It was concluded that CSE can enhance the passively sensitized HASMC proliferation and the expression of PKC alpha. PKC and its alpha subtype may contribute to this process. Our results suggest cigarette may play an important role in ASMCs proliferation of asthma through PKC signal pathway.

Role of Protein Kinase C in the Activation of Store-operated Ca^(2+) Entry in Airway Smooth Muscle Cells

Store-operated Ca2＋ channels （SOCs） are plasma membrane Ca2＋ permeable channels activated by depletion of intracellular Ca2＋ store. Ca2＋ entry through SOCs is known as store-operated Ca2＋ entry （SOCE）, which plays an important role in the functional regulation of airway smooth muscle cells （ASMCs）. Protein kinase C （PKC） has been shown to have an activating or inhibiting effect on SOCE, depending on cell types and PKC isoforms that are involved. In ASMCs, the effect of PKC on SOCE has not been elucidated so far. In this study, the role of PKC in the activation of SOCE in rat ASMCs was examined by using Ca2＋ fluorescence imaging technique. The results showed that acute application of PKC activators PMA and PDBu did not affect SOCE induced by the sarcoplasmic reticulum Ca2＋-ATPase （SERCA） inhibitor thapsigargin. The non-selective PKC inhibitor chelerythrine significantly inhibited thapsigargin- and bradykinin-induced SOCE. RT-PCR assay identified PKCα, δ and ε isoforms in rat ASMCs. PKCα-selective inhibitor G6976 and PKCε-inhibiting peptide Epsilon-V1-2 had no effect on SOCE; by contrast, PKCδ-selective inhibitor rottlerin attenuated SOCE dramatically, suggesting that PKCδ was the major PKC isoform involved in the activation of SOCE in ASMCs. Moreover, PKC down-regulation by extended exposure to high doses of PMA or PDBu also reduced SOCE, confirming the essential role of PKC in the activation of SOCE in ASMCs. In addition, PKC down-regulation did not influence the expression of stromal interaction molecule 1 （STIM1） and Orai1, two elementary molecules in the regulation and activation of SOCs. These results identified PKCδ as an essential PKC isoform involved in the activation of SOCE, and confirmed that PKC regulates the function of ASMCs in a SOCE-dependent manner.

Midkine ameliorates LPS-induced apoptosis of airway smooth muscle cells via the Notch2 pathway

Objective:To evaluate the effect of midkine on lipopolysaccharide(LPS)-induced airway smooth muscle cells(ASMCs).Methods:LPS-stimulated acute lung injury model was used to analyze the effect of midkine on ASMCs in vitro.Recombinant midkine and midkine siRNA were used to investigate the role of Notch2 signaling pathway.Cell proliferation was assessed using Cell Counting Kit-8 assay.Additionally,apoptosis was measured by flow cytometry and protein and mRNA expression of midkine and Notch2 was assessed by Western blotting and qPCR,respectively.Immunofluorescence analysis was also conducted.Results:LPS increased the mRNA and protein expression of midkine and Notch2.Midkine silencing reduced LPS-induced midkine and Notch2 expression.In addition,midkine silencing further reduced the viability and increased apoptosis of ASMCs induced by LPS,which was attenuated by recombinant midkine.Conclusions:The midkine/Notch2 signaling pathway plays a regulatory role in ASMC proliferation and apoptosis in airway inflammation.

Effect of basic fibroblast growth factor on the proliferation, migration and phenotypic modulation of airway smooth muscle cells

Background Proliferation, cell migration and phenotypic modulation of airway smooth muscle cells （ASMCs） are important features of airway remodelling in asthma. The precise cellular and molecular mechanisms that regulate ASMCs proliferation, migration and phenotypic modulation in the lung remain unknown. Basic fibroblast growth factor （bFGF）, a highly specific chemotactic and mitogenic factor for many cell types, appears to be involved in the development of airway remodelling. Our study assessed whether bFGF directly stimulates the proliferation, migration and phenotypic modulation of ASMCs. Methods Confluent and growth arrested human ASMCs were treated with human recombinant FGF. Proliferation was measured by BrdU incorporation and cell counting. Migration was examined using Boyden chamber apparatus. Expressions of smooth muscle （sm）-α-actin and sm-myosin heavy chain （MHC） isoform 1 were determined by RT-PCR and Westem blot analysis. Results It was found that hrbFGF （10 ng/ml）, when added to ASMCs, induced a significant increase in BrdU uptake and cell number by ASMCs as compared to controls and a significant increase in ASMCs migration with respect to controls. The mRNA and protein expressions of sm-α-actin and sm-MHC in ASMCs that were stimulated with hrbFGF decreased with respect to controls. Conclusion It appears that bFGF can directly stimulate proliferation and migration of ASMCs, however, the expressions of cells＇ contractive phenotype decreased.

Cigarette smoke extract promotes proliferation of airway smooth muscle cells in asthmatic rats via regulating cyclin D1 expression

Background Increased proliferation of airway smooth muscle cells （ASMCs） are observed in asthmatic patients and smoking can accelerate proliferation of ASMCs in asthma. To elucidate the molecular mechanisms leading to these changes, we studied in vitro the effect of cigarette smoke extract （CSE） on the proliferation of ASMCs and the expression of cyclin D1, an important regulatory protein implicated in cell cycle. Methods ASMCs cultured from 8 asthmatic Brown Norway rats were studied. Cells between passage 3 and 6 were used in the study and were divided into control group, pcDNA3.1 group, pcDNA3.1-antisense cyclin D1 （ascyclin D1） group, CSE group, CSE＋pcDNA3.1 group and CSE＋pcDNA3.1-ascyclin D1 group based on the conditions for intervention. The proliferation of ASMCs was examined with cell cycle analysis, MTT colorimetric assay and proliferating cell nuclear antigen （PCNA） immunocytochemical staining. The expression of cyclin D1 was detected by reverse transcriptase-PCR （RT-PCR） and Western blotting. Results （1） The percentage of S＋G2M phase, absorbance value at 490 nm wavelength （A490） and the expression rate of PCNA protein in CSE group were （31.22±1.17）%, 0.782±0.221, （90.2±7.0）% respectively, which were significantly increased compared with those of control group （18.36±1.02）%, 0.521±0.109, and （54.1±3.5）%, respectively） （P 〈0.01）. After the transfection with antisense cyclin D1 plasmid for 30 hours, the percentage of S＋G2M phase, A490 and the expression rate of PCNA protein in ASMCs were much lower than in untreated cells （P 〈0.01）. （2） The ratios of A490 of cyclin D1 mRNA in CSE group was 0.288±0.034, which was significantly increased compared with that of control group （0.158±0.006） （P 〈0.01）. After the transfection with antisense cyclin D1 plasmid for 30 hours, the ratios of A49o of cyclin D1 mRNA in ASMCs was much lower than in untreated cells （P 〈0.01）. （3） The ratios of A490 of cyclin D1 protein expression in CSE group was 0.375±0.008, which was significantly increased compared with that of control group （0.268±0.004） （P 〈0.01）. After the transfection with antisense cyclin D1 plasmid for 30 hours, the ratios of A490 of cyclin D1 protein expression in ASMCs was much lower than in untreated cells （P 〈0.01）. Conclusion CSE may increase the proliferation of ASMCs in asthmatic rats via regulating cyclin D1 expression.

Contribution of protein kinase C to passively sensitized human airway smooth muscle cells proliferation

Background Airway smooth muscle proliferation plays an important role in airway remodeling in asthma. But little is known about the intracellular signal pathway in the airway smooth muscle cell proliferation in asthma. The objective of this paper is to investigate the contribution of protein kinase C (PKC) and its alpha isoform to passively sensitized human airway smooth muscle cells (HASMCs) proliferation. Methods HASMCs in culture were passively sensitized with 10% serum from asthmatic patients,with non-asthmatic human serum treated HASMCs used as the control. The proliferation of HASMCs was examined by cell cycle analysis,3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazoliumbromide (MTT) colorimetric assay and proliferating cell nuclear antigen (PCNA) immunofluorescence staining. The effect of PKC agonist phorbol 12-myristate 13-acetate (PMA) and PKC inhibitor Ro-31-8220 on the proliferation of HASMCs exposed to human asthmatic serum and non-asthmatic control serum was also examined by the same methods. The protein and mRNA expression of PKC-α in passively sensitized HASMCs were detected by immunofluorescence staining and reverse transcription-polymerase chain reaction. Results The percentage of S phase,absorbance (value A) and the positive percentage of PCNA protein expression in HASMCs passively sensitized with asthmatic serum were (16.30±2.68)%,0.430±0.060 and (63.4±7.4)% respectively,which were significantly increased compared with HASMCs treated with control serum [(10.01±1.38)%,0.328±0.034 and (37.2±4.8)%,respectively] ( P <0.05). After HASMCs were passively sensitized with asthmatic serum,they were treated with PMA,the percentage of S phase,value A and the positive percentage of PCNA protein expression were (20.33±3.39)%,0.542±0.065 and (76.0±8.7)% respectively,which were significantly increased compared with asthmatic serum sensitized HASMCs without PMA( P <0.05). After HASMCs passively sensitized with asthmatic serum were treated with Ro-31-8220,the percentage of S phase,value A and the positive percentage of PCNA protein expression were (11.21±1.56)%,0.331±0.047 and (38.8±6.0)% respectively,which were significantly decreased compared with asthmatic serum sensitized HASMCs without Ro-31-8220 ( P <0.05). The relative ratio of value A of PKC-α mRNA and the positive percentage of PKC-α protein expression in passively sensitized HASMCs were 1.23±0.10 and (61.1±9.4)% respectively, which were significantly increased compared with HASMCs treated with control serum [1.05±0.09 and (34.9±6.7)%,respectively] ( P <0.05). Conclusions The proliferation of HASMCs passively sensitized with human asthmatic serum is increased. PKC and its alpha isoform may contribute to this proliferation.

The signal transduction pathway in the proliferation of airway smooth muscle cells induced by urotensin Ⅱ

Background Human urotensin Ⅱ (UⅡ) is the most potent mammalian vasoconstrictor identified so far. Our previous study showed that UⅡ is a potent mitogen of airway smooth muscle cells (ASMC) inducing ASMC proliferation in a dose-dependent manner. The signal transduction pathway of UⅡ mitogenic effect remains to be clarified. This study was conducted to investigate the signal transduction pathway in the proliferation of ASMC induced by UⅡ. Methods In primary cultures of rat ASMCs,activities of protein kinase C (PKC),mitogen-activated protein kinase (MAPK) and calcineurin (CaN) induced by UⅡ were measured. The effect of CaN on PKC and MAPK was studied by adding cyclosporin A (CsA),a specific inhibitor of CaN. Using H_7 and PD_ 98059 , inhibitors of PKC and MAPK,respectively,to study the effect of PKC and MAPK on CaN. The cytosolic free calcium concentration induced by UⅡ was measured using Fura-2/AM. Results UⅡ 10 -7 mol/L stimulated ASMC PKC and MAPK activities by 44% and 24% ( P <0.01), respectively,after incubating for 20 minutes. It increased CaN activity in a time-dependent manner,being 1.68 times as that of control for 24 hours ( P <0.01). It promoted the cytosolic free calcium concentration increase of 18% ( P <0.01). CsA 10 -6 mol/L and H_7 50 μmol/L inhibited UⅡ-stimulated CaN activity by 45% ( P <0.01) and 21% ( P <0.05),respectively,while PD_ 98059 50 μmol/L had no effect on CaN activity ( P >0.05). CsA 10 -6 mol/L inhibited UⅡ-stimulated PKC activity by 14% ( P <0.05),while having no effect on MAPK activity ( P >0.05). Conclusions UⅡ increases cytosolic free calcium concentration and activates PKC,MAPK and CaN. The signal transduction pathway between PKC and CaN has cross-talk.

Effects of pinacidil on proliferation of cultured rabbit airway smooth muscle cells induced by endothelin-1

It has been found that the potassium channel dysfunction of the membrane of airway smooth muscle cells (ASMCs) is closely associated with proliferation of ASMCs.~1 Preliminary research has demonstrated that pinacidil, an ATP sensitive potassium channel (K_(ATP)) opener, could play a remarkable role in the prevention and treatment of antigen induced bronchial asthma in guinea pigs.~2 (This study)was designed to investigate further the role and molecular mechanism of the proliferation of ASMCs: a chief pathological change of the nonacute phase of bronchial asthmatic episodes.

Effect of vascular endothelial growth factor and its receptor KDR on human airway smooth muscle cells proliferation

Airway remodeling with inflammatory cell infiltration, epithelial shedding, basement membrane thickening and increased mass of airway smooth muscle (ASM) is an important determinant of bronchial obstruction and hyperresponsiveness in asthma.^(1,2) Increased ASM mass is by far the most important abnormality responsible for excessive airway narrowing and compliance of the airway wall in asthma.^(1-3) ASM growth and proliferation in asthma is a complex phenomenon of which the underlying mechanisms are difficult to investigate in vivo. The increased amount of ASM in asthmatics is an indication of abnormal cell proliferation and growth, but little is known regarding the molecular mechanisms and factors that regulate ASM cell proliferation and growth in asthma.

Effects of Shenmai and Aminophylline on Apoptosis of Small Airway Smooth Muscle Cells and the Expression of Relevant Genes in Rats with Emphysema

The effects of Shenmai injection (SMI) and am inophylline on apoptosis of sm all airway smooth muscle cells (SASMC) and the Fas/ Fas L expression in rats with papain- induced em physe- ma were investigated.Rat emphysema model was established by a single intratracheal instillation of papain.Apoptosis and Fas/Fas L expression of SASMC were detected by im munohistochemistry SABC and TU NEL assay at day1,3,5 ,7,15 ,30 after modeling,and the effect of SMI and am inophylline on them were observed.The results indicated that the Fas/Fas L expression positive rate in SASMC was2 .31± 0 .5 5 /1.2 8± 0 .4 7respectively.After a single intratracheal instillation of papain,the expression of Fas/Fas L positive rate in the placebo group was increased in a tim e- dependent manner.SMI could inhibit the expression of Fas/ Fas L ,but aminophylline couldn't. The positive rate of apoptosis in the control group was 0 .87± 0 .32 .After a single intratracheal in- stillation of papain,the SASMC apoptosis positive rate in the placebo group was increased in a tim e- dependent manner.The SASMC apoptosis rate in all groups was declined after treatment with SMI,but the effect of am inophylline was notobvious.Itwas dem onstrated thatin the patho- genesis of emphysem a Fas/Fas L played an important role in the regulation of SASMC apoptosis. SMI influenced the expression of Fas/ Fas L and declined SASMC apoptosis by inhibiting the releas- ing of inflamm atory m edia and played an im portant role in the therapy of em physema.

AIRWAY SMOOTH MUSCLE CELLS CULTURE AND APPLYING PERSPECTIVES

In order to study the physiological or pathophysiological responsiveness, airway smooth muscle cells were isolated from the rat trachea and cultured. The tracheas of adult rats were obtained by autopsy within 30 minutes after death and placed into a modified Hank’s solution. The experiments were performed on the large branches of the rat bronchi following entry into the lung. At the terminal level of the airway, no cartilage segments were seen. The muscle layer was prepared by careful removal of the connective tissue, cut into small pieces (1 mm3), and dispersed enzymatically (collagenase, elastase) into single cells. Freshly isolated cells could be used the same day. The small muscle pieces and isolated cells were cultured in the modified Hank’s or modified Eagle’s medium with 5% CO2 at 37℃ .

Effects of Mitochondrial ATP-sensitive K^+ Channel on Protein Kinase C Pathway and Airway Smooth Muscle Cell Proliferation in Asthma

The effects of ATP-sensitive mitochondrial K + channel(mitoK ATP) on mitochondrial membrane potential(Δψm),cell proliferation and protein kinase C alpha(PKCα) expression in airway smooth muscle cells(ASMCs) were investigated.Thirty-six Sprague-Dawley(SD) rats were immunized with saline(controls) or ovalbumin(OVA) with alum(asthma models).ASMCs were cultured from the lung of control and asthma rats.ASMCs were treated with diazoxide(the potent activator of mitoK ATP) or 5-hydroxydencanote(5-HD,the inhibitor of mitoK ATP).Rhodamine-123(R-123) was used to detect Δψm.The expression of PKCα protein was examined by using Western blotting,while PKCα mRNA expression was detected by using real-time PCR.The proliferation of ASMCs was measured by MTT assay and cell cycle analysis.In diazoxide-treated normal ASMCs,the R-123 fluorescence intensity,protein and mRNA levels of PKCα,MTT A values and percentage of cells in S phase were markedly increased as compared with untreated controls.The ratio of G 0 /G 1 cells was decreased(P<0.05) in diazoxide-treated ASMCs from normal rats.However,there were no significant differences between the ASMCs from healthy rats treated with 5-HD and the normal control group.In untreated and diazoxide-treated ASMCs of asthmatic rats,the R-123 fluorescence intensity,protein and mRNA levels of PKCα,MTT A values and the percentage of cells in S phase were increased in comparison to the normal control group.Furthermore,in comparison to ASMCs from asthmatic rats,these values were considerably increased in asthmatic group treated with diazoxide(P<0.05).After exposure to 5-HD for 24 h,these values were decreased as compared with asthma control group(P<0.05).In ASMCs of asthma,the signal transduction pathway of PKCα may be involved in cell proliferation,which is induced by the opening of mitoK ATP and the depolarization of Δψm.

K^+ Channels and Their Effects on Membrane Potential in Rat Bronchial Smooth Muscle Cells

In order to investigate the K+ channels and their effects on resting membrane potential (Em) and excitability in rat bronchial smooth muscle cells (BSMCs), the components of outward K+ channel currents and the effects of K+ channels on Em and tension in rat bronchial smooth muscle were observed by using standard whole-cell recording of patch clamp and isometric tension recording techniques. The results showed that under resting conditions, total outward K+ channel currents in freshly isolated BSMCs were unaffected by ATP-sensitive K+ channel blocker. There were two types of K+ currents: voltage-dependent delayed rectifier K+ channel (Kv) and large conductance calcium-activated K+ channel (BKc.) currents. 1 mmol/L 4-aminopyridine (4-AP, an inhibitor of Kv) caused a significant depolarization (from -8. 7±5. 9 mV to -25. 4±3. 1 mV, n=18, P<0. 001). In contrast, 1 mmol/L tetraethylammonium (TEA, an inhibitor of BKc.) had no significant effect on Em (from -37. 6±4. 8 mV to -36. 8±4.1mV, n=12, P>0. 05). 4-AP caused a concentration-dependent contraction in resting bronchial strips. TEA had no effect on resting tension, but application of 5 mmol/L TEA resulted in a left shift with bigger pD2(the negative logarithm of the drug concentration causing 50% of maximal effect) (from 6. 27±0. 38 to 6. 89±0. 54, n= 10, P<0. 05) in the concentration-effect curve of endothine-1, and a right shift with smaller pD2(from 8. 10±0. 23 to 7. 69±0. 08, n=10, P<0. 05) in the concentration-effect curve of isoprenaline. It was suggested that in rat BSMCs there may be two types of K+ channels, Kv and BKca, which serve distinct roles. Kv participates in the control of resting Em and tension. BKca is involved in the regulation of relaxation or contraction associated with excitation.

Effect of inhibiting miR-155 expression on proliferation and migration of airway smooth muscle cell in patients with COPD

Objective:To investigate the effect of inhibiting miR-155 expression on the proliferation and migration of airway smooth muscle cells(ASMCs)in patients with chronic obstructive pulmonary disease(COPD).Methods:ASMCs were isolated and cultured from 8 patients with COPD(observation group)and 3 patients with benign lung cancer without COPD(control group).The ASMCs were transfected with miR-155 suppression expression plasmid(to detect the expression of miR-155;flow cytometry was used to detect the cell cycler of cell clones;Transwell was used to detect cell migration and invasion;Enzyme-linked immunosorbent aanti-miR-155)and the negative contre;clone formation experiment was used to detect the numbol plasmid(anti-miR-NC),and blank control group was set.Real-time quantitative PCR(RT-qPCR)was usedssay(ELISA)method was used to detect tumor necrosis factor-α(TNF-α),interleukin-6(IL-6)level.Results:The expression level of miR-155 in ASMCs of observation group was significantly higher than that in the control group(P<0.05).The miR-155 expression level in inhibited miR-155 expression group was significantly lower,compared with the negative control group and the blank group(P<0.05).In the inhibited miR-155 expression group,the proportion of G0-G1 phase cells was increased,the proportion of S phase cells was decreased,the number of cell clones,migration,and the number of invasive cells were decreased,and the levels of TNF-αand IL-6 were increased(P<0.05).Conclusions:Inhibiting the expression of miR-155 can inhibit the proliferation and migration of airway smooth muscle cells in COPD patients,and inhibit the release of proinflammatory factors.

Shenmai Injection(参麦注射液) Inhibiting the Extracellular Signal Regulated Kinase-lnduced Human Airway Smooth Muscle Proliferation in Asthma

Objective： To investigate the relationship between the proliferation of sensitized human airway smooth muscle cells （HASMCs） and the expression of extracellular signal regulated kinase （ERK） and the effect of Shenmai Injection （参麦注射液, SMI） on HASMCs. Methods： The HASMCs cultured in vitro were divided into three groups： （1） control group; （2） sensitized group： containing 10% asthmatic serum; （3） SMI group： further divided into three different concentration subgroups interferred with 10 μL/mL, 50 μL/mL, and 100 μL/mL SMI, respectively. The proliferation of HASMCs was detected using MTT method, the expression of proliferating cell nucleus antigen （PCNA） in HASMCs was detected using immunocytochemical staining, and the expression of phosphoration-ERK1/2 （p-ERK1/2） protein was detected using Western-blot. Results： After passive sensitization, the optical density value （A49o value） of HASMCs was significantly increased from 0.366± 0.086 to 0.839 ± 0.168 （P〈0.05）. In addition, the expression of PCNA was significantly increased from 28.7% ± 5.9% in the control group to 69.8% ±7.5% in the sensitized group （P〈0.05）. At the same time, the expression of p-ERK1/2 in passively sensitized HASMCs was significantly increased compared with the control group （all P〈0.05）. Affer application of 10 μL/mL, 50 μL/mL, and 100 μL/mL SMI to the cultured media of passively sensitized group, the A570 value was significantly decreased from 0.839 ±0.168 to 0.612 ±0.100, 0.412 ± 0.092, and 0.339 ± 0.077, respectively （P〈0.05）. Moreover, the expression of PCNA was significantly decreased from 69.8% ±7.5% to 57.8% ± 6.2%, 40.7%±5.4%, and 26.1% ± 5.2%, respectively. At the same time, the expression of p-ERK1/2 in each SMI group was significantly decreased compared with the sensitized group （all ,P〈0.05）. Conclusion： ERK signal transduction pathway may be involved in the airway remodeling in asthma. The expression of ERK can be inhibited by SMI in a dose-dependent manner, thus preventing the proliferation of HASMCs.

otassium channels in airway smooth muscle and airway hyperreactivity in asthma

Our knowledge of the physiology of ion channels has increased tremendously during the past 20 years because of the advances of the single-channel recording and molecular cloning techniques. More than 50 different identified potassium channels have already been found.1,2 They are distributed ubiquitously in wide variety of cells including airway smooth muscle （ASM） cells and inflammatory cells in airway such as eosinophils, basophils, macrophages and so on.3 Several types of K+ channels have been identified in ASM cells, e.g., a large-conductance, voltgage-dependent Ca2+-activated K+ channel(BKCa), a voltage-dependent delayed-rectifier K+ channel（Kv）, and an ATP-sensitve K+ channel(KATP).1 In such excitable cells,

Changes in delayed rectifier K^+ channel function and its regulation by protein kinase C pathway in bronchial myocytes from asthmatic rats

Objective To investigate changes in the delayed rectifier K + channel (Kv) function and the regulation of Kv by the protein kinase C (PKC) pathway in bronchial myocytes from asthmatic rats. Methods The Kv currents and membrane potentials in bronchial myocytes from asthmatic rats and from controls were observed, using whole cell voltage- and current-patch clamp techniques.Results Bronchial myocytes from asthmatic rats showed a significant reduction in Kv-current density (51.6±9.4 pA/pF, n=14, P<0.01) in comparison with those from control rats (72.4±12.3 pA/pF, n=14) at +50 mV. The current-voltage relationship curve exhibited a significant downward shift. Bronchial myocytes from asthmatic rats had no significantly different capacitances (P>0.05), but had more positive membrane potential ( P<0.01) compared with those from controls. 1 μmol/L phorbol 12-myristate 13-acetate, a PKC activator, caused an obvious reduction in Kv-current density (P<0.01) and a significant downward shift in the current-voltage relationship curve, an effect which was partly abolished by 1 μmol/L Ro31-8220 (a PKC inhibitor); 1 μmol/L phorbol 12-myristate 13-acetate caused more positive membrane potential (Em), from -36.8±5.7 mV to -30.4±7.3 mV, in rat bronchial myocytes (P<0.05). This effect was partly abolished by 1 μmol/L Ro31-8220. Conclusions Bronchial myocytes from asthmatic rats have inhibited Kv function, more positive membrane potential, and higher excitability, all of which can also be induced by PKC activation. These characteristics may contribute to the development of airway hyperreactivity in asthma.