Identification of Atrial Fibrillation-related Inflammatory Genes and Their Association with Immune Cell Infiltration Based on Comprehensive Bioinformatic Analysis
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摘要:
目的 鉴定心房颤动 ( atrial fibrillation,AF)患者的炎症相关基因,并探讨这些基因与浸润免疫细胞在AF的发生发展过程中可能的作用和机制。 方法 通过一系列的生物信息学分析结合机器学习算法识别AF的生物标志物,使用受试者操作特性曲线(receiver operating characteristic,ROC)验证关键基因的预测及诊断价值,采用Spearman 相关分析明确关键基因与浸润免疫细胞的相关性。 结果 筛选出593个差异基因[|log2 (fold change,FC)|>1,P<0.05],7种免疫细胞亚型(P<0.05),获得190个免疫相关差异基因,识别出 3 个生物标志物(IGF1、PTGS2和PPARG),相关性分析结果显示3个标志物与浸润免疫细胞显著相关(P<0.05)。 结论 IGF1、PTGS2和PPARG是AF的炎症相关基因,推测其与免疫细胞浸润过程和途径密切相关。 Abstract:Objective To identify inflammation-related genes in atrial fibrillation (AF) and explore the possible role and mechanism of these genes and infiltrating immune cells in the development of AF. Methods A series of bioinformatics analysis combined with machine learning algorithms to identify biomarkers of AF, the receiver operating characteristic (ROC) curves were used to verify the prediction and diagnostic value of key genes, and Spearman correlation analysis was used to clarify the correlation between key genes and infiltrating immune cells. Results 593 differential genes (| log2 (fold change, FC) |> 1, P <0.05), 7 immune cell subtypes (P <0.05) were selected, 190 immune-related differential genes were obtained, 3 biomarkers (IGF1, PTGS 2 and PPARG), and the correlation analysis showed that 3 markers were significantly associated with infiltrating immune cells (P < 0.05). Conclusion IGF1, PTGS2 and PPARG are inflammation-related genes of AF, which are speculated to be closely related to the process and pathway of immune cell infiltration. -
Key words:
- Atrial fibrillation /
- Bioinformatics analysis /
- Immune infiltration /
- Inflammatory response /
- Biomarkers
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心肌缺血/再灌注损伤(myocardial ischemia-reperfusion injury,MI/RI)是治疗缺血性心脏病的主要障碍[1-3],其最主要机制为I/R(ischemia-reperfusion)过程中局部及全身的炎症反应[4]。IL-6是心肌缺血再灌注损伤时释放的关键因子[5]。心肌I/R后患者血浆中IL-6水平显著升高[6-7],而循环中的高IL-6与心肌损伤、心力衰竭和死亡率相关[8]。低功率聚焦超声辐照靶向微泡,能使IL-6单克隆抗体定点释放,不仅完成了I/R心肌的无创评价[9],同时也减轻了局部炎症反应。通过设置实验参数,超声靶向微泡破坏技术(ultrasound-targeted microbubble destruction,UTMD)不仅能够提升细胞膜通透性,且不会引起细胞的不可逆损伤[10]。本实验通过携IL-6单克隆抗体联合不同辐照强度的UTMD技术治疗MI/RI,为以后MI/RI超声靶向治疗应用于临床提供理论依据。
1. 资料与方法
1.1 动物模型的制备
健康成年日本大耳兔90只购自昆明医科大学动物实验中心,平均体重为2 000~2 500 g,动物许可证为SCXK(滇)2011-0004,随机将其分为三组:A组(15只)关胸对照组、B组(15只)开胸对照组,A、B两组再分为U0、U1、U2三组,每组5只兔,C组(60只)缺血/再灌注组,分成T1~T4时段(T1~T4再灌注时间分别为30 min、60 min、120 min、180 min,将各时段分为U0、U1、U2组,每组5只兔)。A组无需任何处置,B组开胸后相同部位仅穿线不阻断,C组通过自制套管将冠状动脉左前降支(LAD)阻断30 min,解除梗阻,分别给予再灌注30 min、60 min、120 min、180 min制备MI/RI损伤动物模型。其中各U0组均未经超声辐照,U1组、U2组分别选择0.5 w/cm2及0.75 w/cm2强度超声辐照。动态监测各组心电图情况,监测时间点为术前、缺血30 min、再灌注30 min、60 min、120 min、180 min,心肌缺血的改变为心电图上ST段畸变,弓背朝上抬高幅度大于0.5 mV。
1.2 靶向声学造影剂的制备
1.2.1 Biotin(抗体生物素)标记
根据Thermo操作说明书,依照比例(抗体∶Biotin = 1∶15)取13.5 μL Biotin添加至Anti-IL-6抗体液体内,置于避光环境下反应1 h;完成反应后,将以上液体于4 ℃、pH = 7.4 PBS溶液透析过夜;24 h后换液,约6 h后收样品,保存至−20 ℃避光环境下。
1.2.2 抗体和微泡耦联
微量取样枪把500 μg标记有生物素的IL-6抗体添加至1 mL Targestar SA微泡内,常温下进行20~30 min的孵育,连续摇动至冻干粉末彻底分散产生白色乳状、均匀的微泡混悬液,即得到IL-6靶向超声微泡。
1.3 超声靶向微泡破坏技术
兔取左侧卧位,呼吸平缓后,于胸骨左缘放置探头,选择Philips EPIQ75,S5-1探头,频率1.8/3.6 MHz。每组兔行常规超声心动图后,由兔耳缘静脉给予靶向微泡造影剂(剂量为0.05 mL/kg),完成各心肌节段显影并储存图像,待微泡稳定附着于梗死部位心肌组织后,低功率聚焦超声仪对A、B、C3组中的U1组进行强度为0.5 w/cm2的超声辐照,U2组进行0.75 w/cm2的超声辐照(频率均为1 MHz),辐照5 min。取得3组兔各U1、U2组辐照前、后的动态图像后处死实验兔获取心肌组织。图像经QLAB10.5软件分析,以左室乳头肌短轴水平前壁作为关键分析节段,获得对应的心肌视频强度,得到视频强度差值(video intensity difference,VID)。
1.4 酶联免疫吸附(ELISA)实验
取局部心肌组织(各组心肌组织均取结扎位线下5~10 mm,约2 mm厚),将其捣碎后,依照100 mg/mL DH.Z.混合物(内含细胞裂解液、蛋白酶抑制剂)置于4 ℃温度下处理一整夜,在20 000 r/min环境下离心20 min,将上清保存至−80 ℃冰箱内,之后对不同组别兔心肌组织内的IL-6含量进行检测,测得超声辐照前、后心肌组织中IL-6的水平。
1.5 统计学处理
统计分析使用SPSS软件,数值用均数±标准差(
$\bar x$ ±s)表示。两种处理方式作用于同一样本选择配对t检验,同一处理方式作用于两组样本时选择两独立样本t检验,三组间数据的统计分析使用单因素方差分析;P < 0.05为差异有统计学意义。2. 结果
2.1 模型制备情况
90只兔,B组死亡2只,其中1只死亡可能与麻药注射速度较快相关,另1只可能和不正当的手术操作相关。C组4只手术失败,分别为胸膜破裂死亡2只、阻断冠脉30 min后死亡2只,原因可能为诱发室颤。心电图结果显示:套管夹闭LAD后,ST段迅速抬高,再灌注30 min时ST段未降低,45 min时ST段下降,60 min时降到等电位线附近,120 min及180 min时ST段降到等电位线,见图1。
2.2 靶向声学造影剂的制备结果
免疫荧光染色、玻片凝集实验结果显示IL-6单克隆抗体已顺利偶联至Targestar SA微泡表面,见图2、图3。
2.3 心肌声学造影(MCE)
以开始注射造影剂为起点,对A、B、C 3组中的U1与U2组兔心肌组织进行强度为0.5 w/cm2和0.75 w/cm2的超声辐照,于辐照前、后行QLAB定量分析,结果显示:C组中T1~T4时段U2组心肌组织的超声视频强度差值高于U1组,差异有统计学意义(P < 0.05),T1~T4时段U1组及U2进行组内两两比较,差异无统计学意义(P > 0.05),见图4、表1。
表 1 各组兔超声辐照前后视频强度差值[dB,($\bar x\pm s$ )]Table 1. Video intensity difference of each group before and after ultrasonic irradiation [dB,($\bar x\pm s$ )]分组 n A组 B组 C组 T1(30 min) T2(60 min) T3(120 min) T4(180 min) U1 30 0.15 ± 0.14 5.18 ± 2.83 9.33 ± 1.14 9.32 ± 1.65 10.31 ± 2.75 9.64 ± 1.51 U2 30 0.33 ± 0.04 5.28 ± 1.13 10.99 ± 1.79* 12.05 ± 1.34* 12.34 ± 3.13* 11.61 ± 2.46* 与U1组比较,*P < 0.05。 2.4 各组兔心肌组织ELISA定量分析结果
T1~T4时段U2组VID值较U1组高(P < 0.05),T1~T4时段U2组及U1组VID值进行组内两两比较,差异无统计学意义(P > 0.05)。ELISA结果显示:超声辐照后,T1~T4时段,U2组IL-6含量比U1组低(P < 0.05),T1~T4时段U1组及U2组IL-6含量差值进行组内两两比较,差异有统计学意义(P < 0.05)。
U0组:A组与B组心肌组织内的IL-6含量差异无统计学意义(P > 0.05)。A组和B组分别与C组中T1-T4时段心肌组织IL-6含量比较,差异有统计学意义(P < 0.05),见表2。
表 2 不同时段各组兔心肌组织内IL-6水平[pg/mL,($\bar x\pm s$ )]Table 2. IL-6 level in myocardial tissue of rabbits in different time periods [pg/mL,($\bar x\pm s$ )]分组 n A组 B组 C组 T1(30 min) T2(60 min) T3(120 min) T4(180 min) U0 30 13.01 ± 2.02* 14.85 ± 2.18* 38.76 ± 5.01△▲ 54.29 ± 4.86△▲ 79.88 ± 4.02△▲ 75.25 ± 3.23△▲ U1 30 12.75 ± 2.73* 11.24 ± 2.58* 15.25 ± 2.64△ 28.02 ± 4.74△ 39.25 ± 3.31△ 36.58 ± 2.89△ U2 30 12.00 ± 2.13* 11.01 ± 2.07* 10.47 ± 1.85 25.24 ± 3.51 35.39 ± 2.31 32.36 ± 2.91 与C组比较,*P < 0.05;与U2组比较,△P < 0.05;与U1组比较,▲P < 0.05。 U1及U2组:A组、B组心肌组织IL-6含量差异无统计学意义(P > 0.05)。U2组T1-T4时段心肌组织的IL-6含量分别与U0、U1组T1-T4时段相比,差异有统计学意义(P < 0.05)。U1组T1-T4时段心肌组织的IL-6含量与U0组相比,差异有统计学意义(P < 0.05)。
2.5 VID值与心肌组织内IL-6水平差值的相关性分析
0.5 w/cm2强度超声辐照前后心肌组织内IL-6水平差值与VID值呈正相关(rU1 = 0.745,P < 0.05),0.75 w/cm2强度与VID值亦为正相关(rU2 = 0.734,P < 0.05),见图5。
2.6 超声辐照后各组兔心肌组织HE染色病理结果
开胸对照组中未经超声辐照、经0.5 w/cm2强度及0.75 w/cm2强度超声辐照的心肌细胞未见明显变化;再灌注120 min未经超声辐照的心肌细胞排列稍紊乱,细胞形态尚清晰,细胞间隙增宽,可见炎性细胞浸润;0.5 w/cm2强度超声辐照下,心肌细胞排列较规整,损伤较未经超声辐照组有所缓解,炎性细胞浸润减少;0.75 w/cm2强度超声辐照下,心肌细胞损伤缓解明显,排列基本正常,炎性细胞极少量浸润,见图6。
3. 讨论
炎症反应在MI/RI的发生发展过程中扮演着重要角色,研究表明,心肌缺血再灌注时,IL-6及其受体表达明显增加,且与预后相关[11]。在MI/RI早期,缺血、缺氧心肌细胞的IL-6呈高表达[12],IL-6能够诱导中性粒细胞、心肌细胞表达CD11b/CD18和细胞间黏附分子1,从而引起心肌损伤,还可通过诱导心肌细胞的凋亡参与再灌注后的心室重塑。因此,降低MI/RI心肌组织局部IL-6的浓度,对于缺血再灌注心肌损伤及再灌注后的心室重塑至关重要。
UTMD技术是一种新的区域或组织特异性基因传递手段,实现了超声在分子层面的显影,而其在疾病靶向治疗方面的研究也逐步深入。UTMD介导的mir-206能抑制细胞迁移和侵袭并促进细胞凋亡,使其成为HCC的潜在治疗方法[13],UTMD辅助外泌体miR-21进入心脏可显著降低细胞死亡,恢复心脏功能[14],UTMD介导的GDF11基因对老年小鼠的缺血心肌有更好的保护作用,其疗效优于腹腔注射[15]。鉴于UTMD在疾病中的应用及IL-6在MI/RI中的重要作用,本研究以IL-6为治疗靶点,将UTDM和低功率聚焦超声联合用于MI/RI中,以期筛选出UTDM治疗再灌注损伤的最佳条件。
本研究发现,在未经超声辐照及0.5 w/cm2、0.75 w/cm2强度超声辐照的MI/RI心肌组织中IL-6的含量均随着再灌注时间的延长而逐渐升高,于120 min达峰值,随后下降。这与以往的研究结果一致[16],MI/RI早期即引起心肌组织内产生高水平的IL-6,且心肌组织损伤程度随着再灌注时间的延长逐渐加重。VID值表示超声辐照后携IL-6单克隆抗体的靶向微泡与心肌组织内IL-6的中和量。同一强度超声辐照各组心肌组织后,组间VID值分析无统计学差异,提示当超声辐照强度相同时,超声能损害的微泡量及IL-6的中和量,不因再灌注时间变化而改变。同一时段,0.75 w/cm2强度超声辐照心肌组织的VID值较0.5 w/cm2强度的高,说明在相同再灌注时段,辐照强度增大,IL-6的中和量增多。0.5 w/cm2强度辐照心肌组织的VID值和IL-6水平差值为正相关,0.75 w/cm2强度辐照心肌组织的VID值和IL-6水平差值亦为正相关。进一步表明VID值能反映心肌组织IL-6的中和量。
超过一定范围的超声辐照强度会引起细胞损伤,前期研究发现1.0~1.5 w/cm2超声辐照强度可致心肌细胞出现炎症反应 [17]。在本研究中,经过0.5 w/cm2及0.75 w/cm2强度的超声辐照后,对照组心肌细胞未出现明显损伤,说明0.5 w/cm2及0.75 w/cm2强度的超声辐照不会对心肌细胞造成损伤。此外,再灌注损伤后,经过超声辐照的心肌细胞与未经辐照的心肌细胞比较,不仅心肌细胞损伤程度较前减轻,炎性细胞浸润也明显减少,且0.75 w/cm2强度的超声辐照对心肌细胞再灌注损伤的治疗效果优于0.5 w/cm2。
本实验通过携IL-6单克隆抗体微泡联合UTMD技术,对不同时间段再灌注损伤心肌进行不同强度超声辐照,IL-6抗体与心肌组织抗原结合,有效缓解炎性反应,进而对MI/RI发挥靶向治疗作用。在不引起心肌损伤的超声辐照强度下,越早干预、辐照强度越高,减轻炎症反应的效果越佳。本实验仅设定了0.5 w/cm2及0.75 w/cm2两个辐照强度,因此,存在一定局限性。
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[1] Zhu Y,Shi J,Zheng B,et al. Genetic findings in patients with primary fibrotic atrial cardiomyopathy[J]. European Journal of Medical Genetics,2022,65(3):104429. doi: 10.1016/j.ejmg.2022.104429 [2] Litviňuková M,Talavera-López C,Maatz H,et al. Cells of the adult human heart[J]. Nature,2020,588(7838):466-472. doi: 10.1038/s41586-020-2797-4 [3] Zaidi Y, Aguilar E G, Troncoso M, et al. Immune regulation of cardiac fibrosis post myocardial infarction. [Z]. 2021: 77, 109837. [4] Tian Y,Liu S,Zhang Y,et al. Immune infiltration and immunophenotyping in atrial fibrillation[J]. Aging (Albany NY),2023,15(1):213-229. doi: 10.18632/aging.204470 [5] Wynn T A,Vannella K M. Macrophages in tissue repair,regeneration,and fibrosis[J]. Immunity,2016,44(3):450-462. doi: 10.1016/j.immuni.2016.02.015 [6] Newman A M,Liu C L,Green M R,et al. Robust enumeration of cell subsets from tissue expression profiles[J]. Nat Methods,2015,12(5):453-457. doi: 10.1038/nmeth.3337 [7] Langfelder P,Horvath S. WGCNA: An R package for weighted correlation network analysis[J]. BMC Bioinformatics,2008,9(1):559. doi: 10.1186/1471-2105-9-559 [8] Liu Y, Shi Q, Ma Y, et al. The role of immune cells in atrial fibrillation[J]. J Mol Cell Cardiol, 2018: 123, 198-208. [9] Zhang Y L,Teng F,Han X,et al. Selective blocking of CXCR2 prevents and reverses atrial fibrillation in spontaneously hypertensive rats[J]. J Cell Mol Med,2020,24(19):11272-11282. doi: 10.1111/jcmm.15694 [10] Hulsmans M,Schloss M J,Lee I H,et al. Recruited macrophages elicit atrial fibrillation[J]. Science,2023,381(6654):231-239. doi: 10.1126/science.abq3061 [11] Grune J,Yamazoe M,Nahrendorf M. Electroimmunology and cardiac arrhythmia[J]. Nature reviews cardiology,2021,18(8):547-564. doi: 10.1038/s41569-021-00520-9 [12] Sun Z,Zhou D,Xie X,et al. Cross-talk between macrophages and atrial myocytes in atrial fibrillation[J]. Basic Res Cardiol,2016,111(6):63. doi: 10.1007/s00395-016-0584-z [13] Bosco M C. Macrophage polarization: reaching across the aisle?[J]. J Allergy Clin Immunol,2019,143(4):1348-1350. doi: 10.1016/j.jaci.2018.12.995 [14] Wen S,Yan W,Wang L. mRNA expression disturbance of complement system related genes in acute arterial thrombotic and paroxysmal atrial fibrillation patients[J]. Ann Palliat Med,2020,9(3):835-846. doi: 10.21037/apm.2020.04.18 [15] Liu L,Zheng Q,Lee J,et al. PD-1/PD-L1 expression on CD(4+) T cells and myeloid DCs correlates with the immune pathogenesis of atrial fibrillation[J]. J Cell Mol Med,2015,19(6):1223-1233. doi: 10.1111/jcmm.12467 [16] Cheng W L,Kao Y H,Chen Y C,et al. Macrophage migration inhibitory factor increases atrial arrhythmogenesis through CD74 signaling[J]. Transl Res,2020,216:43-56. doi: 10.1016/j.trsl.2019.10.002 [17] Chen Y,Fu L,Pu S,et al. Systemic lupus erythematosus increases risk of incident atrial fibrillation: A systematic review and meta-analysis[J]. Int J Rheum Dis,2022,25(10):1097-1106. doi: 10.1111/1756-185X.14403 [18] Kunamalla A,Ng J,Parini V,et al. Constitutive expression of a dominant-negative TGF-β type II receptor in the posterior left atrium leads to beneficial remodeling of atrial fibrillation substrate[J]. Circ Res,2016,119(1):69-82. doi: 10.1161/CIRCRESAHA.115.307878 [19] Liang Y,Zhou Y,Wang J,et al. Downregulation of fibromodulin attenuates inflammatory signaling and atrial fibrosis in spontaneously hypertensive rats with atrial fibrillation via inhibiting TLR4/NLRP3 signaling pathway[J]. Immun Inflamm Dis,2023,11(10):e1003. doi: 10.1002/iid3.1003 [20] Gao L,Kan C,Chen X,et al. Mechanism of action of Zhi Gan Cao decoction for atrial fibrillation and myocardial fibrosis in a mouse model of atrial fibrillation: A network pharmacology-based study[J]. Comput Math Methods Med,2022,2022:4525873. [21] Raman K,Aeschbacher S,Bossard M,et al. Whole blood gene expression differentiates between atrial fibrillation and sinus rhythm after cardioversion[J]. PLoS One,2016,11(6):e157550. [22] Troncoso R,Ibarra C,Vicencio J M,et al. New insights into IGF-1 signaling in the heart[J]. Trends Endocrinol Metab,2014,25(3):128-137. doi: 10.1016/j.tem.2013.12.002 [23] Fujita M,Takada Y K,Takada Y. Insulin-like growth factor (IGF) signaling requires αvβ3-IGF1-IGF type 1 receptor (IGF1R) ternary complex formation in anchorage independence,and the complex formation does not require IGF1R and Src activation[J]. J Biol Chem,2013,288(5):3059-3069. doi: 10.1074/jbc.M112.412536 [24] Zhao Z,Li R,Wang X,et al. Attenuation of atrial remodeling by aliskiren via affecting oxidative stress,inflammation and PI3K/Akt signaling pathway[J]. Cardiovasc Drugs Ther,2021,35(3):587-598. doi: 10.1007/s10557-020-07002-z [25] Cheng W,Zhu Y,Wang H. The MAPK pathway is involved in the regulation of rapid pacing-induced ionic channel remodeling in rat atrial myocytes[J]. Mol Med Rep,2016,13(3):2677-2682. doi: 10.3892/mmr.2016.4862 [26] Dalli J,Chiang N,Serhan C N. Elucidation of novel 13-series resolvins that increase with atorvastatin and clear infections[J]. Nat Med,2015,21(9):1071-1075. doi: 10.1038/nm.3911 [27] Kim S F,Huri D A,Snyder S H. Inducible nitric oxide synthase binds,S-nitrosylates,and activates cyclooxygenase-2[J]. Science,2005,310(5756):1966-1970. doi: 10.1126/science.1119407 [28] Wang Z,Zeng Z,Hu Y,et al. Network pharmacology and pharmacological mechanism of CV-3 in atrial fibrillation[J]. Evid Based Complement Alternat Med,2022,2022:5496299. [29] Barroso I,Gurnell M,Crowley V E,et al. Dominant negative mutations in human PPARgamma associated with severe insulin resistance,diabetes mellitus and hypertension[J]. Nature,1999,402(6764):880-883. doi: 10.1038/47254 [30] Park S H,Choi H J,Yang H,et al. Endoplasmic reticulum stress-activated C/EBP homologous protein enhances nuclear factor-kappaB signals via repression of peroxisome proliferator-activated receptor gamma[J]. J Biol Chem,2010,285(46):35330-35339. doi: 10.1074/jbc.M110.136259 [31] Chen Y L, Chuang J H, Wang H T, et al. Altered expression of circadian clock genes in patients with atrial fibrillation is associated with atrial high-rate episodes and left atrial remodeling[J]. Diagnostics (Basel), 2021, 11(1): 90. [32] Wang N,Yang G,Jia Z,et al. Vascular PPARgamma controls circadian variation in blood pressure and heart rate through Bmal1[J]. Cell Metab,2008,8(6):482-491. doi: 10.1016/j.cmet.2008.10.009 -