黃 曉,張軍民,蔣 麗,王 麗, 魯 莎,蔡文瑩
馬爾尼菲青霉酸性磷酸酶在宿主氧化殺傷中的作用
黃 曉,張軍民,蔣 麗,王 麗, 魯 莎,蔡文瑩
目的 探討馬爾尼菲青霉(Penicilliummarneffei, PM)酸性磷酸酶(Acidphosphatase,ACP)在宿主氧化殺傷中的作用。方法 在培養(yǎng)基中加入不同濃度H2O2模擬氧化應(yīng)激環(huán)境,于25 ℃和37 ℃震蕩培養(yǎng)后檢測(cè)上清液中ACP的活性。通過(guò)用特定培養(yǎng)基誘導(dǎo)酶分泌、滅活、抑制劑處理的方法獲得不同酶活性的PM分生孢子,建立分生孢子與巨噬細(xì)胞共培養(yǎng)模型;利用H2DCFDA標(biāo)記聯(lián)合流式細(xì)胞術(shù)檢測(cè)巨噬細(xì)胞ROS的釋放量,CFU及透射電鏡觀察巨噬細(xì)胞對(duì)PM的殺傷情況。結(jié)果PM菌絲相及酵母相均能分泌ACP,加入H2O2后兩相ACP活性均提高;誘導(dǎo)PM分泌酸性磷酸酶,巨噬細(xì)胞ROS釋放量及對(duì)菌體殺傷能力被抑制;將酶抑制后,巨噬細(xì)胞ROS釋放量增加,對(duì)菌體殺傷能力增強(qiáng)。結(jié)論P(yáng)M在氧化應(yīng)激條件下能通過(guò)分泌ACP抑制巨噬細(xì)胞ROS產(chǎn)生,從而抵御宿主的氧化殺傷作用。
酸性磷酸酶;馬爾尼菲青霉;巨噬細(xì)胞;氧化殺傷;ROS
馬爾尼菲青霉病是由馬爾尼菲青霉(Penicilliummarneffei,PM)感染引起的深部真菌病,主要累及網(wǎng)狀內(nèi)皮-巨噬細(xì)胞系統(tǒng)[1],常引起全身廣泛播散,病死率高。馬爾尼菲青霉是一種溫度依賴性雙相真菌, 25 ℃條件下呈菌絲相生長(zhǎng),可產(chǎn)生大量分生孢子;37 ℃時(shí)呈酵母相,感染人及動(dòng)物時(shí)以酵母形態(tài)存在于宿主體內(nèi)。PM分生孢子可經(jīng)呼吸道進(jìn)入宿主體內(nèi)隨即被支氣管、肺部的巨噬細(xì)胞所吞噬,以酵母相在巨噬細(xì)胞內(nèi)分裂增殖。巨噬細(xì)胞吞噬病原體后可通過(guò)呼吸爆發(fā)產(chǎn)生大量氧活性簇(ROS)對(duì)菌體進(jìn)行氧化殺傷,作為一種細(xì)胞內(nèi)病原菌,PM如何抵御巨噬細(xì)胞的氧化殺傷作用在細(xì)胞內(nèi)存活目前尚未明確。
酸性磷酸酶(acidphosphatase,ACP)是一類廣泛存在于微生物及動(dòng)植物的水解酶,被認(rèn)為是許多病原菌的重要毒力因子[2-5],主要通過(guò)抑制宿主ROS產(chǎn)生發(fā)揮其毒力作用。既往有文獻(xiàn)報(bào)道PM可分泌ACP[6],然而ACP與PM致病性方面的研究尚未見(jiàn)報(bào)道。本實(shí)驗(yàn)通過(guò)研究PM在氧化應(yīng)激條件下ACP的分泌情況及其酶學(xué)性質(zhì),抑制ACP活性后對(duì)巨噬細(xì)胞ROS產(chǎn)生及殺傷能力的影響,初步探討酸性磷酸酶在馬爾尼菲青霉抵御巨噬細(xì)胞氧化殺傷中的作用,以明確馬爾尼菲青霉在巨噬細(xì)胞氧化應(yīng)激條件下存活的機(jī)制。
1.1 材料
1.1.1 主要試劑 DMEM培養(yǎng)基及胎牛血清購(gòu)自美國(guó)Gibco公司,馬鈴薯葡萄糖瓊脂培養(yǎng)基(PDA)購(gòu)自日本和光純藥工業(yè)株式會(huì)社, Acid Phosphatase檢測(cè)試劑盒、Acid Phosphatase 抑制劑(正釩酸鈉、酒石酸鈉、鉬酸鈉、氟化鈉、β-甘油磷酸鈉)均購(gòu)自Sigma公司,DCFH-DA熒光測(cè)定試劑盒購(gòu)自上海杰美基因醫(yī)藥科技有限公司。酸性磷酸酶誘導(dǎo)培養(yǎng)基配制試劑購(gòu)自廣州威佳生物公司(葡糖糖; NaNO3; MgSO4.7H2O; KCl; FeSO4.7H2O;檸檬酸;檸檬酸鈉)。
1.1.2 菌株來(lái)源 馬爾尼菲青霉SUMS0152 株(已經(jīng)形態(tài)學(xué)及DNA測(cè)序鑒定) ,由中山大學(xué)孫逸仙紀(jì)念醫(yī)院醫(yī)學(xué)真菌研究中心提供,分離自一名血液病患兒的血液標(biāo)本。細(xì)胞系:BALB/c小鼠來(lái)源的巨噬細(xì)胞株RAW264.7購(gòu)自中國(guó)典型培養(yǎng)物保藏中心(CCTCC)(武漢,湖北)。
1.2 方法
1.2.1PM培養(yǎng)上清及分生孢子制備 將PM分別接種于含有2mmol/L H2O2的酸性磷酸酶誘導(dǎo)液體培養(yǎng)基中(配制方法參照文獻(xiàn)[7]),對(duì)照管加入等量生理鹽水代替H2O2,25 ℃及37 ℃ , 150 r/ min 振蕩培養(yǎng)96 h,從各培養(yǎng)管中取2 mL菌懸液離心過(guò)濾得到上清液,-20 ℃保存?zhèn)溆?。PM接種于馬鈴薯斜面培養(yǎng)(PDA),25 ℃室溫下培養(yǎng)7~9 d,PBS反復(fù)沖洗培養(yǎng)基表面,離心去色素,生理鹽水重懸,鏡下觀察為單細(xì)胞性分生孢子,計(jì)數(shù)4 ℃保存?zhèn)溆谩?/p>
1.2.2 巨噬細(xì)胞培養(yǎng) 無(wú)菌操作復(fù)蘇RAW264.7細(xì)胞株,用含10%小牛血清的DMEM培養(yǎng)基培養(yǎng)2~3 d,EDTA-胰酶消化傳代2~3次后轉(zhuǎn)至六孔板,調(diào)整細(xì)胞密度為1×106/mL,每孔1 mL。根據(jù)實(shí)驗(yàn)要求分組。
1.2.3ACP活性檢測(cè) 以 p-NPP為底物,將菌懸液50 μL加入96孔板中再加入等量ACP底物,混勻,37 ℃孵育1 h后用0.5N NaOH溶液終止反應(yīng),將反應(yīng)板放入酶標(biāo)儀于405波長(zhǎng)處測(cè)各孔吸光值。根據(jù)說(shuō)明書公式計(jì)算其對(duì)應(yīng)的ACP活性(單位為Units/mL)。
1.2.4 PAS染色觀察巨噬細(xì)胞對(duì)PM的吞噬 巨噬細(xì)胞與PM共培養(yǎng)1 h制備細(xì)胞爬片,滴加PAS固定液5 min,水洗待干,滴加PASI液10 min,水洗待干,滴加PASII液室溫避光孵育30 min,流水沖洗數(shù)分鐘,蘇木素復(fù)染1~2 min,水洗待干,光學(xué)顯微鏡下觀察分生孢子被吞噬情況。
1.2.5 H2DCFDA標(biāo)記檢測(cè)巨噬細(xì)胞的ROS水平 分為3組,第1組:未加入分生孢子;第2組:加入未處理的分生孢子;第3組:加入預(yù)處理的分生孢子。PM分生孢子與RAW264.7細(xì)胞共培養(yǎng)2 h(菌與細(xì)胞比例5∶1),棄培養(yǎng)液, PBS洗3次, 每孔加入H2DCFDA 工作液(終濃度為5 μmol/L),37 ℃,5%CO2培養(yǎng)箱中避光孵育30 min,PBS洗2次,上機(jī)檢測(cè)熒光強(qiáng)度。
1.2.6 CFU檢測(cè)ACP對(duì)RAW264.7細(xì)胞殺傷P.marneffei分生孢子的影響 分組:①空白對(duì)照組;②酶抑制組;酶抑制組:將分生孢子置于含1 mmol/L正釩酸鈉的生理鹽水中37 ℃孵育4 h,空白對(duì)照組:未加入抑制劑在同等條件下孵育。PM分生孢子與RAW264.7細(xì)胞共培養(yǎng)2 h(菌與細(xì)胞比例5∶1), PBS洗去未被吞噬的PM,每孔以4 ℃預(yù)冷的無(wú)菌雙蒸水1 mL裂解細(xì)胞,倍比稀釋至1 000倍,取100 μL涂SDA平皿培養(yǎng)基,37℃溫箱培養(yǎng)2~3 d,菌落計(jì)數(shù)。每孔涂3個(gè)復(fù)培養(yǎng)皿,重復(fù)實(shí)驗(yàn)3次
1.3 數(shù)據(jù)分析 所有數(shù)據(jù)采用SPSS13.0軟件進(jìn)行統(tǒng)計(jì)處理,數(shù)據(jù)描述以平均值±標(biāo)準(zhǔn)差表示,組間比較采用t檢驗(yàn)分析,P<0.05為差異有統(tǒng)計(jì)學(xué)意義。
2.1 H2O2對(duì)酶活性的影響PM菌絲相與酵母相均可以分泌ACP,在H2O2培養(yǎng)基中菌絲相與酵母相ACP活性均明顯提高,差異有統(tǒng)計(jì)學(xué)意義。說(shuō)明氧化壓力可以促進(jìn)PM分泌ACP(表1)。
2.2 共培養(yǎng)體系的建立 將巨噬細(xì)胞RAW264.7與PM共培養(yǎng)1 h后,用PAS染色在光學(xué)顯微鏡下觀察巨噬細(xì)胞的吞噬情況。在巨噬細(xì)胞的胞漿內(nèi)可看到被PAS染成桃紅色的PM分生孢子。說(shuō)明成功建立了共培養(yǎng)體系(圖1)。
表1 H202對(duì)PM酸性磷酸酶活性的影響±s)
注:*與0 mmol/L比較,P<0.05
*P<0.05 compared with control group (0 mmol/L).
圖1PM與RAW264.7共培養(yǎng),箭頭指示被吞噬的PM分生孢子(光鏡,1 000×)
Fig.1 PM conidia are phagocyticed by RAW264.7 after co-culture (original magnification×1 000), Bar=50 μm
2.3 流式細(xì)胞術(shù)檢測(cè)巨噬細(xì)胞內(nèi)ROS水平 流式細(xì)胞術(shù)檢測(cè)巨噬細(xì)胞內(nèi)ROS水平,結(jié)果顯示LPS、LPS+酶抑制分生孢子、 LPS+滅活分生孢子、LPS+酶誘導(dǎo)分生孢子組平均熒光強(qiáng)度分別為:167.5±20.43;434.0±14.72;509.0±22.30;41.14±12.36各組間差異有統(tǒng)計(jì)學(xué)意義(P<0.01)。LPS可以刺激巨噬細(xì)胞呼吸爆發(fā)釋放ROS(圖2B),加入經(jīng)酸性磷酸酶誘導(dǎo)后的分生孢子ROS降低(圖2E),而將酶誘導(dǎo)的分生孢子用抑制劑處理或滅活后ROS升高(分別為圖2C、D),說(shuō)明酸性磷酸酶可以抑制巨噬細(xì)胞ROS產(chǎn)生(圖2A為不加熒光的對(duì)照組),(圖2)。
2.4 CFU檢測(cè)PM被巨噬細(xì)胞殺傷情況 不同酶活性PM與巨噬細(xì)胞共培養(yǎng)兩小時(shí),CFU檢測(cè)分生孢子被殺傷情況。結(jié)果顯示,酶誘導(dǎo)分生孢子、酶抑制分生孢子組CFU分別為:1.68×104±0.15與0.61×104±0.15,兩者有統(tǒng)計(jì)學(xué)差異(P<0.001)。誘導(dǎo)酸性磷酸酶分泌可以使PM存活率提高,而該酶被抑制后PM存活率降低,說(shuō)明酸性磷酸酶可以抵御巨噬細(xì)胞的殺傷作用(圖3)。
A:對(duì)照組;B:LPS;C:LPS+酶抑制分生孢子;D:LPS+滅活分生孢子; E:LPS+酶誘導(dǎo)分生孢子
Intracellular ROS generation was assayed by flow cytometry with the H2DCFA fluorescent prob.
A: control group; B: LPS; C: LPS+Enzyme inhibited conidia;D: LPS+Enzyme inactivated conidia; E: LPS+Enzyme activated conidia.
圖2 RAW264.7細(xì)胞與不同酶活性的PM共培養(yǎng)2 h后,細(xì)胞內(nèi)ROS的釋放量
Fig.2 RAW 264.7 was co-cultured with PM conidia of different enzyme activity for 2 h
The survival of PM conidia were assayed by CFU.
圖3 RAW264.7細(xì)胞與不同酶活性的PM共培養(yǎng)2h后,PM的存活率
Fig.3 RAW 264.7 was co-cultured with PM conidia of different enzyme activity for 2 h
2.5 電鏡下觀察PM被巨噬細(xì)胞殺傷情況 不同酶活性PM與巨噬細(xì)胞共培養(yǎng)2 h,可見(jiàn)巨噬細(xì)胞表面有細(xì)長(zhǎng)的突起將PM分生孢子捕獲及包繞。數(shù)量不等的分生孢子被內(nèi)吞入細(xì)胞,存在于膜包裹的吞噬體內(nèi)或游離于胞漿。共培養(yǎng)后酶誘導(dǎo)分生孢子形態(tài)結(jié)構(gòu)未見(jiàn)明顯改變,可見(jiàn)到完整的細(xì)胞壁,胞內(nèi)可見(jiàn)脂肪滴(圖4-1);而酸性磷酸酶被抑制的分生孢子可見(jiàn)形態(tài)改變,細(xì)胞壁與細(xì)胞膜分離、細(xì)胞皺縮,細(xì)胞壁與細(xì)胞內(nèi)結(jié)構(gòu)模糊,呈降解狀態(tài)(圖4-2)。提示酶抑制分生孢子抵御巨噬細(xì)胞殺傷能力較酶誘導(dǎo)分生孢子弱,進(jìn)一步說(shuō)明酸性磷酸酶可以抵御巨噬細(xì)胞的殺傷作用。
透射電鏡(20 000×)下觀察,可見(jiàn)完整的PM分生孢子(黑色箭頭所示),細(xì)胞內(nèi)可見(jiàn)脂肪滴(紅色箭頭所示)
The morphology of intact conidia (black arrow) and intracellular lipid droplets were observed by TEM(20 000×)(red arrow)
透射電鏡(20 000×)下觀察,可見(jiàn)結(jié)構(gòu)被破壞的PM分生孢子(黑色箭頭所示),細(xì)胞壁與細(xì)胞膜分離,細(xì)胞結(jié)構(gòu)模糊,呈降解狀態(tài)
As shown by TEM (20 000×), the structure of conidia were damaged (black arrow), cell membranes were separated from cell walls, conidia appeared degraded with unclear cell shape.
圖4-1PM酶誘導(dǎo)分生孢子在巨噬細(xì)胞內(nèi)生存情況
圖4-2PM酶抑制分生孢子在巨噬細(xì)胞內(nèi)生存情況
Fig. 4-1 Survival of enzyme activated PM conidia in macrophage were observed by TEM
Fig. 4-2 Survival of enzyme inhibited PM conidia
馬爾尼菲青霉 (Penicilliummarneffei,PM)是青霉屬中唯一的溫度依賴性雙相真菌,屬于機(jī)會(huì)致病菌。近幾年隨著腫瘤化療、器官移植、艾滋病的流行免疫缺陷患者日益增多,馬爾尼菲青霉病發(fā)病率逐漸增加。該菌在室溫25℃培養(yǎng)時(shí)呈菌絲相,產(chǎn)生分生孢子;37 ℃培養(yǎng)或感染人體后呈酵母相,為致病相。PM分生孢子經(jīng)呼吸道進(jìn)入宿主體內(nèi)后被巨噬細(xì)胞吞噬,當(dāng)宿主免疫系統(tǒng)缺陷時(shí)PM不能被完全清除,可在巨噬細(xì)胞內(nèi)以酵母細(xì)胞分裂增殖,并致全身播散。作為一種細(xì)胞內(nèi)病原體,PM在巨噬細(xì)胞內(nèi)存活并繁殖是其感染宿主的首要條件,被認(rèn)為是其致病的關(guān)鍵[8-9]。既往研究表明,PM在宿主巨噬細(xì)胞內(nèi)能夠通過(guò)調(diào)控異檸檬酸裂解酶(acuD)、銅鋅超氧化物歧化酶(sodA)、過(guò)氧化氫酶-過(guò)氧化物酶(cpeA)、熱休克蛋白70(hsp70)等的表達(dá)而抵御吞噬細(xì)胞的抗真菌活性,以利于其在宿主細(xì)胞內(nèi)生存[9-12]。
酸性磷酸酶(acidphosphatase,ACP)[16]是一類廣泛存在于微生物及動(dòng)植物的水解酶,被認(rèn)為是許多病原菌重要的毒力因子[2-3,5,7]。如結(jié)核分枝桿菌可分泌一種結(jié)構(gòu)、性質(zhì)與真菌相似的酸性磷酸酶[4],該酶可通過(guò)降低胞內(nèi)pH值而減弱免疫細(xì)胞的氧化應(yīng)激,敲除ACP調(diào)控基因結(jié)核分枝桿菌毒力下降[5,17]。弗朗西斯氏菌屬[2]、貝氏柯克斯體[3]等分泌的ACP可通過(guò)抑制ROS抵御宿主的氧化殺傷。Youngchim等[6]采用定性的方法發(fā)現(xiàn)PM也能分泌酸性磷酸酶,但其與PM致病性的關(guān)系尚未見(jiàn)文獻(xiàn)報(bào)道。
本研究在培養(yǎng)基中加入H2O2模擬體內(nèi)氧化應(yīng)激環(huán)境,通過(guò)定量的方法檢測(cè)培養(yǎng)上清液中ACP的活性,結(jié)果顯示H2O2能提高ACP的活性,提示氧化應(yīng)激條件下可以刺激PM分泌ACP。將PM用ACP抑制劑預(yù)處理后與巨噬細(xì)胞共培養(yǎng)兩小時(shí)后檢測(cè)巨噬細(xì)胞內(nèi)ROS的水平及其對(duì)PM的吞噬殺傷作用,研究結(jié)果發(fā)現(xiàn)ACP未被抑制時(shí)巨噬細(xì)胞內(nèi)ROS水平較低,對(duì)菌體吞噬殺傷作用較弱;而ACP被抑制后,巨噬細(xì)胞ROS水平上升,對(duì)PM吞噬殺傷能力增強(qiáng),提示巨噬細(xì)胞可以通過(guò)產(chǎn)生ROS殺傷菌體,而PM在巨噬細(xì)胞內(nèi)可以通過(guò)分泌ACP抑制ROS的產(chǎn)生抵御巨噬細(xì)胞的殺傷作用。我們推測(cè)巨噬細(xì)胞吞噬PM后通過(guò)呼吸爆發(fā)產(chǎn)生大量活性氧族(ROS)等殺傷菌體,PM在宿主氧化應(yīng)激環(huán)境下可分泌ACP等物質(zhì)抑制ROS從而抵抗宿主的氧化殺傷;當(dāng)宿主免疫力正常時(shí),巨噬細(xì)胞的氧化系統(tǒng)和PM的抗氧化系統(tǒng)處于平衡狀態(tài),病原體被殺死;相反,當(dāng)人免疫缺陷時(shí),PM抗殺傷機(jī)制占優(yōu)勢(shì)則可引起馬爾尼菲青霉病。
我們的研究結(jié)果顯示,馬爾尼菲青霉在氧化應(yīng)激條件下可分泌酸性磷酸酶,抑制該酶后巨噬細(xì)胞內(nèi)ROS水平升高,對(duì)PM的吞噬作用增強(qiáng),提示ACP可能通過(guò)抑制巨噬細(xì)胞活性氧族(ROS)產(chǎn)生抵御宿主的氧化殺傷從而參與PM的致病過(guò)程,具體的機(jī)制有待進(jìn)一步研究闡明。
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Zhang Jun-min, Email: junminmx@163.com
Role of acid phosphatase ofPenicilliummarneffeiin the host oxidative damage
HUANG Xiao,ZHANG Jun-min,JIANG Li,WANG Li,LU Sha,CAI Wen-ying
(DepartmentofDermatology,SunYat-senMemorialHospital,SunYat-senUniversity,Guangzhou510120,China)
We investigated the role of acid phosphatase ofPenicilliummarneffeiin the host oxidative damage.Penicilliummarneffeiwere inoculated in liquid medium containing H2O2at 37 ℃ or 25 ℃. Cell-free supernatants were tested for acid phosphatase activity and enzymatic properties. After pretreated with acid phosphatase inhibitor,Penicilliummarneffeiconidia were cultivated with macrophages. The levels of ROS generated by macrophages were determined by flow cytometry with the H2DCFA fluorescent prob. The activities of livingPenicilliummarneffeiin the cells were observed by electron microscopy. CFU was used to evaluate the influence of acid phosphatase on the sterilization ability of macrophages. Results showed that both mycelial and yeast phases ofPenicilliummarneffeiexpressed acid phosphatase activity. Enzyme activity was improved after exposed to H2O2. After acid phosphatase was inhibited, the amount of ROS was increased comparing with the control group. The capacity of macrophages for phagocytizing and sterilizing conidia was enhanced. It’s suggested that acid phosphatase can preventPenicilliummarneffeifrom oxidative damage by inhibiting the levels of ROS.
Penicilliummarneffei; acid phosphatase; macrophage; oxidative damage; ROS
10.3969/j.issn.1002-2694.2015.09.007
廣東省自然科學(xué)基金資助(No.S2013010015189)
張軍民,Email:junminmx@163.com
中山大學(xué)孫逸仙紀(jì)念醫(yī)院皮膚科,廣州 510120
Supported by the fund of Natural Science Foundation of Guangdong Province (No. S2013010015189)
R379
A
1002-2694(2015)09-0817-05
2015-03-11;
2015-07-17