富氢液对脓毒症小鼠心肌细胞线粒体自噬的影响

为评价富氢液（hydrogen-rich saline,HRS）对脓毒症小鼠心肌细胞线粒体自噬的调节及其对心功能障碍的治疗作用,选取72只雄性C57BL/6J小鼠作为研究对象,采用随机数字表法分为假手术组（Sham组）、假手术+富氢液组（Sham+HRS组）、脓毒症组（CLP组）、CLP+富氢液组（CLP+HRS组）,每组18只。采用盲肠结扎穿孔法建立小鼠CLP模型。Sham+HRS组和CLP+HRS组分别于造模后1、6 h时腹腔注射富氢液10 mL·kg^-1。每组随机取6只小鼠,于造模后24 h时收集小鼠颈动脉血样,采用ELISA法测定血液肿瘤坏死因子α（tumor necrosis factor-α,TNF-α）、白细胞介素（interleukin-1β,IL-1β）、肌钙蛋白I（cardiac troponin I,cTnI）和肌酸激酶同工酶（creatine kinase MB,CK-MB）水平;于造模后24 h时取心肌组织,采用荧光素-荧光酶发光法检测ATP,荧光分光光度法检测线粒体膜电位（mitochondrial membrane potential,MMP）。造模后24 h采用Western blot法测定心肌组织线粒体自噬相关蛋白微管关联蛋白轻链3Ⅱ/轻链3Ⅰ（microtubule-associated protein 1 light/protein 3 light,LC3Ⅱ/LC3Ⅰ）和蛋白62（protein 62,P62）的表达水平。结果显示,与Sham组比较,CLP组血清TNF-α、IL-1β、cTnI和CK-MB水平升高,心肌ATP、MMP水平下降,心肌LC3Ⅱ/LC3Ⅰ表达水平上调,P62表达水平下调,差异有统计学意义（P<0.05）;与CLP组比较,CLP+HRS组血清TNF-α、IL-1β、cTnI和CK-MB含量下降,心肌组织ATP、MMP水平升高,LC3Ⅱ/LC3Ⅰ表达水平进一步上调,P62表达进一步下调（P<0.05）。结果表明,富氢液对脓毒症小鼠心功能障碍的治疗作用可能是通过调节心肌细胞线粒体自噬实现的。研究旨在探讨富氢液对脓毒症小鼠心功能障碍的治疗作用及机制,以期为富氢液的临床转化提供理论依据。     

miR-135b-5p抑制脓毒症引起的小鼠急性肺损伤(ALI)的作用及机制*

目的: 探究miR-135b-5p在小鼠脓毒症(sepsis)引起的急性肺损伤(ALI)模型中的表达水平及其对小鼠肺部炎症反应和细胞焦亡的影响。方法: 将C57BL/6小鼠随机分为6组,每组8只,通过盲肠结扎穿刺法(CLP)手术构建CLP诱导的脓毒症小鼠模型:腹腔注射0.1 mg/kg的巴比妥麻醉,腹部纵向切开暴露盲肠,结扎盲肠并用注射器针头进行穿孔,挤出部分肠道内容物后缝合伤口。假手术组(Sham组)开腹后不做任何处理缝合伤口,无CLP手术处理。治疗组分为CLP+NC mimic组,CLP+miR-135b-5p mimic组,CLP+NC mimic+empty vector组,CLP+消皮素D (GSDMD)组,CLP+miR-135b-5p mimic+GSDMD组。治疗组小鼠在CLP手术前一周皮下注射200 μl溶解于生理盐水的NC mimic(200 nmol/L),miR-135b-5p mimic(200 nmol/L),empty vector(100 nmol/L),GSDMD vector(100 nmol/L),每天注射1次,连续一周。术后24 h采用二氧化碳窒息法实施安乐死。采用qRT-PCR检测小鼠肺组织样本中miR-135b-5p和GSDMD mRNA的表达水平;苏木精-伊红(HE)染色检测小鼠肺组织形态和损伤状态;采用5 ml生理盐水冲洗小鼠右肺3次,每次持续约3~5 min,收集肺泡灌洗液(BALF),酶联免疫吸附实验(ELISA)检测小鼠肺泡灌洗液(BALF)中GSDMD、白介素1β(IL-1β)和白介素18(IL-18)的表达水平;蛋白免疫印迹法检测小鼠肺组织内含NLR家族PYRIN域蛋白3(NLRP3),半胱氨酸天冬氨酸蛋白水解酶1(caspase 1)以及切割后的N-端GSDMD端蛋白结构域(cleaved-GSDMD-N)的表达水平。双荧光素酶报告基因检测系统验证miR-135b-5p与GSDMD的靶向结合关系。结果: 与对照组相比,CLP组小鼠肺组织中有大量的炎症细胞浸润,肺泡损伤,细胞间质水肿及肺泡塌陷等病理特征,小鼠肺组织内细胞焦亡相关蛋白(NLRP3,caspase-1和GSDMD)的表达水平明显增加(P<0.01),但miR-135b-5p的表达水平明显下调(P<0.01);与CLP组相比,超表达miR-135b-5p能够明显抑制CLP诱导的小鼠肺组织内细胞焦亡(P<0.01),靶向抑制GSDMD的表达水平(P<0.01);超表达GSDMD能够逆转超表达miR-135b-5p对肺组织细胞焦亡的抑制作用(P<0.01),超表达miR-135b-5p能够通过靶向GSDMD抑制小鼠BALF中IL-1β及IL-18的表达水平(P<0.01)。结论: miR-135b-5p靶向下调GSDMD抑制细胞焦亡,改善脓毒症引起的ALI,为脓毒症诱导的ALI治疗提供了潜在的治疗靶点和理论依据。     

MOTS-c通过TLR4对肠源性脓毒症的作用及其机制

目的:脓毒症是机体对感染产生的全身性炎症反应综合征,由于具体机制尚不明确,临床治疗效果不佳,死亡率一直居高不下。本实验通过研究线粒体来源多肽MOTS-c通过影响Toll样受体4在肠源性脓毒症小鼠模型中的作用及其相关机制,寻找新的临床治疗靶标,为感染性疾病的研究开拓新的思路。方法:在盲肠结扎穿孔(CLP)所致肠源性脓毒症小鼠给予MOTS-c处理后检测小肠组织中检测炎症相关因子TNF-α,IL-6,IL-1β水平,检测TLR4表达水平,并且在野生型和TLR4过表达小鼠中构建CLP模型并给予MOTS-c处理,将其与对照组进行比较,以明确TLR4在MOTS-c对脓毒症影响中的作用。结果:在MOTS-c组CLP小鼠模型中,小鼠体内促炎因子TNF-α,IL-6,IL-1β水平与对照组相比显著降低(P0.05),此外,TLR4与对照组相比表达下降,进一步在TLR4过表达小鼠CLP模型中对小鼠给予MOTS-c处理发现,MOTS-c对小鼠CLP的抗炎作用被抑制,小鼠体内促炎性因子TNF-α,IL-6,IL-1β水平与野生型小鼠比较均显著上升,差异具有统计学意义,说明过表达TLR4逆转了MOTS-c的抗炎作用,提示MOTS-c可以在肠源性脓毒症中发挥抗炎作用,并且此过程可能依赖于TLR4。结论:MOTS-c可以在脓毒症中抑制小肠上皮细胞中TLR4过度激活,最终抑制炎症,因此可能对脓毒症有治疗效果,有望用于临床治疗。     

重组人脑利钠肽对脓毒症相关性脑病小鼠神经细胞凋亡的治疗作用

目的:探讨重组人脑利钠肽(recombinant human brain natriuretic peptide, rhBNP)对脓毒症小鼠脑病理损伤和认知功能障碍的治疗效应,明确其脑保护作用机制。方法:采用盲肠结扎穿刺法(Cecal ligation and puncture, CLP)建立脓毒症小鼠模型。在CLP手术后6小时皮下注射rhBNP,相同容积的生理盐水被作为对照,连续14天,每日一次。通过旷场实验,评价动物基础运动状态、探索能力和焦虑情绪;采用条件相关恐惧实验,检测动物情景相关记忆能力变化。TUNEL染色检测动物海马CA1区神经细胞凋亡变化;蛋白质免疫印迹法(Western blot, WB)检测动物海马组织TNF-α、Caspase-8和Caspase-3蛋白表达水平变化。结果:在旷场实验中,与Sham+Veh组小鼠相比较,CLP+Veh组小鼠表现出平均运动速度(P0.0001)、5分钟穿格次数(P0.0001)和中央区域运动时间明显下降(P0.0001)。与CLP+Veh组小鼠相比较,CLP+rhBNP组小鼠旷场中平均运动速度(P=0.35)和5分钟穿格次数(P=0.064)无显著变化,中央区域运动时间明显增加(P=0.0005)。在条件相关恐惧测试中,与Sham+Veh组小鼠相比较,CLP+Veh组小鼠表现为僵直时间比例明显减少(P0.0001)。与CLP+Veh组小鼠相比较,CLP+rhBNP组小鼠表现为僵直时间比例显著增加(P=0.0014)。CLP诱导的脓毒症小鼠表现出海马CA1区神经细胞凋亡。rhBNP治疗可以明显的减轻脑病理变化,并且通过抑制Caspase-3上游信号通路TNF-a-Caspase-8减轻神经细胞凋亡。结论:rhBNP对SAE具有治疗作用,其机制可能与抑制神经细胞凋亡有关。     

抗炎合剂对脓毒症小鼠心肌损伤的保护作用及机制

摘要 目的：探讨抗炎合剂对脓毒症致心肌损伤的保护作用及可能机制。方法：将32只体重22～25 g的雄性C57小鼠随机分为4组：正常组、假手术组、模型组（脓毒症模型）、抗炎合剂组。采用盲肠结扎穿孔术（cecal ligation and puncture，CLP）建立脓毒症模型，模型组、抗炎合剂组在造模后分别用生理盐水、抗炎合剂（Anti-inflammation mixture，AIM）对大鼠进行干预。正常组：正常进食饮水；假手术组：假手术前每天给予生理盐水（1.4 mL/100 g），并腹腔注射生理盐水（5 mg/kg）每日1次，连续3日。第4日行假手术；模型组（CLP组）：CLP术前给予生理盐水（1.4 mL/100 g），每天1次，并腹腔注射生理盐水（5 mg/kg）每日1次，连续3日。第4日CLP；抗炎合剂组：CLP术前给予中药抗炎合剂（1.4 mL/100 g），每天1次，并腹腔注射生理盐水（5 mg/kg）每日1次，连续3日。第4日行CLP；各组分别于手术后24小时行标本采集，采用HE染色和TUNEL染色观察小鼠心肌组织损伤情况，同时检测小鼠血清肿瘤坏死因子-α（TNF-α）和炎症因子白细胞介素-1β（IL-1β）水平。结果：与正常对照组或假手术组相比，CLP模型组小鼠的心肌组织出现大量炎性细胞浸润，心肌细胞凋亡率显著升高（P<0.01）；而抗炎合剂组相较于CLP模型组心肌细胞凋亡率显著下降（P<0.01）。与正常对照组或假手术组相比，CLP模型小鼠血清TNF-α、IL-1β水平显著升高（P<0.001），而中药抗炎合剂组TNF-α、IL-1β水平相较于模型组显著降低（P<0.01）。此外，与正常对照组和假手术组相比，模型组SIRT1 mRNA水平和蛋白表达水平显著降低，抗炎合剂显著提高SIRT1的mRNA和蛋白表达水平。结论：抗炎合剂可能通过提高SIRT1的表达，抑制CLP脓毒症小鼠的炎症反应，进而减轻心肌损伤。     

miR-155通过促进炎症因子释放参与脓毒症肠道屏障功能障碍的发生发展

摘要 目的：探讨miR-155在脓毒症致肠道功能障碍中的表达及作用。方法：（1）临床实验：以2022年5月至2022年8月入住新疆医科大学第一附属医院重症医学科的脓毒症患者和同期健康体检者为研究对象,根据急性胃肠损伤分级（AGI）将脓毒症患者分为AGI组和非AGI组。根据28 d生存情况分为存活组和死亡组,采用实时荧光定量反转录-聚合酶链反应（qRT-PCR）法前瞻性观察各组外周血miR-155的变化。（2）体内实验：将20只雄性S/D大鼠按照随机数字表法分为假手术组（sham组）和盲肠结扎穿孔术组（CLP组）,采用qRT-PCR及Western blot法检测miR-155、肠道紧密连接蛋白（ZO-1、claudin-1）的表达,ELISA法检测大鼠肠道组织中IL-1β、IL-6、IL-18的表达水平。(3)体外实验：培养人结直肠腺癌细胞（Caco-2）,并分为正常对照组(完全培养基培养48 h)、脂多糖组（完全培养基培养24 h后加入10 μg/mL LPS处理24 h）。采用qRT-PCR检测miR-155的表达。在倒置荧光显微镜下观察细胞形态的变化。采用CCK-8检测细胞活力。采用免疫荧光观察Caco-2细胞中紧密连接蛋白ZO-1分布的变化。并行细胞旁通透性实验,观察两组细胞旁通透性的变化。结果：（1）脓毒症组和健康对照组相比,脓毒症患者外周血miR-155较健康对照组明显升高,差异具有统计学意义（P<0.05）。AGI组患者外周血miR-155表达较非AGI组明显升高,差异具有统计学意义(P<0.05)。脓毒症死亡患者外周血miR-155表达显著升高(P<0.05)。（2）应用CLP模型进行体内动物实验,CLP组大鼠肠道组织miR-155表达较假手术组（sham组）明显升高。CLP组大鼠肠道紧密连接蛋白（ZO-1、claudin-1）较sham组下降,差异具有统 计学意义(P<0.05)。ELISA结果提示,CLP大鼠肠道组织中IL-1β、IL-6、IL-18水平较sham组显著升高（P<0.05）,且肠道组织中miR-155水平与IL-1β、IL-6、IL-18呈正相关（r=0.542,r=0.906,r=868,P<0.05）。（3）与正常对照组相比,经LPS处理后细胞形态破坏、细胞间紧密连接破坏、细胞活力减弱、细胞旁通透性增加。结论：脓毒症发生时伴有肠道屏障功能障碍,miR-155在脓毒症肠道屏障功能障碍中表达升高,并可能通过促进炎症因子的释放参与脓毒症肠道屏障功能障碍的发生发展。miR-155异常表达对脓毒症患者早期肠道功能障碍诊断及预后的评估具有重要价值,可作为脓毒症早期肠道损伤诊断及预后情况的重要指标。     

人参皂苷Rg3通过调节自噬减轻脓毒症心肌损伤

摘要 目的：探讨人参皂苷Rg3（ginsenoside Rg3,Rg3）对脓毒症介导的心肌损伤的作用效果及机制。方法：本研究通过对小鼠进行盲肠结扎穿孔手术的方法构建脓毒症模型。32只BALB/c小鼠随机分为假手术组（Sham组）、脓毒症组（CLP组）、人参皂苷Rg3治疗组（Rg3+CLP组）以及自噬抑制剂干预组（3-MA+Rg3+CLP组）,每组8只。术后18 h分别留取各组小鼠血浆及心肌组织。通过ELISA方法检测白细胞介素-1β（IL-1β）、白细胞介素-18（IL-18）、乳酸脱氢酶（LDH）、肌酸激酶同工酶MB（CK-MB）及半胱氨酸蛋白酶-3（Caspase-3）表达水平。通过HE染色观察心肌组织形态结构的变化。应用Western-blot方法检测自噬及NLRP3炎性小体相关蛋白（NLRP3、ASC、Caspase-1）的表达。结果：与Sham组相比,CLP组小鼠心肌组织结构紊乱,炎性细胞浸润明显。另外,Caspase-3活性增加,NLRP3炎性小体相关蛋白（NLRP3、ASC、Caspase-1）表达升高,差异均有统计学意义（P＜0.05）。与CLP组相比,外源应用Rg3组小鼠心肌组织炎性细胞浸润减少,并且Caspase-3活性降低,NLRP3炎性小体相关蛋白表达下降,差异有统计学意义（P＜0.05）,而部分自噬相关蛋白表达升高。应用自噬抑制剂后,较单纯应用Rg3组,心肌组织损伤明显,而NLRP3炎性小体活性增加,差异有统计学意义（P＜0.05）。结论：脓毒症时NLRP3炎性小体激活,释放大量的细胞因子,进而导致心肌损伤。而Rg3治疗后,可以调节心肌细胞自噬,抑制NLRP3炎性小体激活,进而减轻细胞因子对心肌细胞的损伤。本研究表明Rg3可能通过调节心肌自噬,抑制NLRP3炎性小体的激活,进而减轻脓毒症时心脏的损伤。     

线粒体来源肽MOTS-c通过抑制促炎性因子分泌改善脓毒症小鼠生存率

目的:研究一种新的线粒体来源肽MOTS-c对脓毒症小鼠生存率的影响。方法:构建了LPS和CLP诱导的两种脓毒症小鼠模型,观察MOTS-c治疗对小鼠生存率及促炎性因子TNF-α和IL-6水平的影响。Western-blot方法检测MOTS-c对巨噬细胞NF-κB活化的影响。结果:与对照组相比,MOTS-c治疗使LPS诱导的脓毒症小鼠生存率从10%提高至60%(P0.05),而CLP诱导的脓毒症小鼠生存率则从10%提高至50%(P0.05)。ELISA结果显示,在LPS诱导的脓毒症模型中,MOTS-c治疗使小鼠血浆中的TNF-α和IL-6的水平显著降低(P0.05);与之类似,在CLP诱导的脓毒症模型中,小鼠血浆和腹腔灌洗液中的TNF-α和IL-6的水平也显著下降(P0.05)。机制研究结果表明,MOTS-c能够显著抑制巨噬细胞中LPS诱导的转录因子NF-κB的活化。结论:MOTS-c能够提高脓毒症小鼠的生存率,其机制可能与抑制NF-κB的转录激活、降低体内促炎性细胞因子的水平相关。     

Shh信号参与调控BMP9诱导的间充质干细胞成骨分化

目的：观察sonic hedgehog（Shh）信号通路在骨形态发生蛋白9（BMP9）诱导的小鼠间充质干细胞（MSCs）C3H10T1/2和C2C12成骨分化中的作用,并初步探讨其作用机制。方法：Shh信号通路抑制剂Cyclopamine和激活剂Purmorphamine以及过表达Shh腺病毒分别作用于BMP9处理的C3H10T1/2和C2C12细胞,碱性磷酸酶（ALP）检测早期成骨指标ALP,茜素红S染色检测晚期成骨指标钙盐沉积,RT-PCR检测Shh信号相关基因以及成骨关键转录因子的表达,Western blot检测Shh的表达,荧光素酶报告基因检测Smad1/5/8的转录调控活性。结果：BMP9促进Shh信号相关基因的表达,激活Shh信号可增强BMP9诱导的C3H10T1/2和C2C12细胞早晚期成骨分化并促进了BMP9诱导的Smad荧光素酶活性,抑制Shh信号后作用相反。结论：激活Shh信号通路可促进BMP9诱导的小鼠MSCs成骨分化,抑制其活性后作用相反。     

Transgenic Expression of FoxM1 Promotes Endothelial Repair following Lung Injury Induced by Polymicrobial Sepsis in Mice

Enhancing endothelial barrier integrity for the treatment of acute lung injury (ALI) is an emerging novel therapeutic strategy. Our previous studies have demonstrated the essential role of FoxM1 in mediating endothelial regeneration and barrier repair following lipopolysaccharide-induced lung injury. However, it remains unclear whether FoxM1 expression is sufficient to promote endothelial repair in experimental models of sepsis. Here, employing the FoxM1 transgenic (FoxM1 Tg) mice, we showed that transgenic expression of FoxM1 promoted rapid recovery of endothelial barrier function and survival in a clinically relevant model of sepsis induced by cecal ligation and puncture (CLP). We observed lung vascular permeability was rapidly recovered and returned to levels similar to baseline at 48 h post-CLP challenge in FoxM1 Tg mice whereas it remained markedly elevated in WT mice. Lung edema and inflammation were resolved only in FoxM1 Tg mice at 24 h post-CLP. 5-bromo-2-deoxyuridine incorporation assay revealed a drastic induction of endothelial proliferation in FoxM1 Tg lungs at 24h post-CLP, correlating with early induction of expression of FoxM1 target genes essential for cell cycle progression. Additionally, deletion of FoxM1 in endothelial cells, employing the mouse model with endothelial cell-restricted disruption of FoxM1 (FoxM1 CKO) resulted in impaired endothelial repair following CLP challenge. Together, these data suggest FoxM1 expression in endothelial cells is necessary and sufficient to mediate endothelial repair and thereby promote survival following sepsis challenge.     

Role of endotoxin in the expression of endothelial selectins after cecal ligation and perforation

The objectives of this study were to determine 1) the changes in endothelial cell adhesion molecule expression that occur in a clinically relevant model of sepsis and 2) the dependence of these changes on endotoxin [lipopolysaccharide (LPS)]. The dual radiolabeled monoclonal antibody technique was used to quantify the expression of E- and P-selectin in LPS-sensitive (C3HeB/FeJ) and LPS-insensitive (C3H/HeJ) mice that were subjected to acute peritonitis by cecal ligation and perforation (CLP). At 6 h after CLP, the expression of both E- and P-selectin was increased in the gut (mesentery, pancreas, and small and large bowel) compared with the sham-operated and/or control animals, with a more marked response noted in LPS-insensitive mice. The lung also exhibited an increased P-selectin expression in both mouse strains. An accumulation of granulocytes, assessed using tissue myeloperoxidase activity, was noted in the lung and intestine of LPS-sensitive but not LPS-insensitive mice exposed to CLP. These results indicate that the CLP model of sepsis is associated with an upregulation of endothelial selectins in the gut vasculature and that enteric LPS does not contribute to this endothelial cell activation response.     

Hepatic Scavenger Receptor BI Protects Against Polymicrobial-induced Sepsis through Promoting LPS Clearance in Mice

Recent studies revealed that scavenger receptor BI (SR-BI or Scarb1) plays a critical protective role in sepsis. However, the mechanisms underlying this protection remain largely unknown. In this study, using Scarb1^I179N mice, a mouse model specifically deficient in hepatic SR-BI, we report that hepatic SR-BI protects against cecal ligation and puncture (CLP)-induced sepsis as shown by 75% fatality in Scarb1^I179N mice, but only 21% fatality in C57BL/6J control mice. The increase in fatality in Scarb1^I179N mice was associated with an exacerbated inflammatory cytokine production. Further study demonstrated that hepatic SR-BI exerts its protection against sepsis through its role in promoting LPS clearance without affecting the inflammatory response in macrophages, the glucocorticoid production in adrenal glands, the leukocyte recruitment to peritoneum or the bacterial clearance in liver. Our findings reveal hepatic SR-BI as a critical protective factor in sepsis and point out that promoting hepatic SR-BI-mediated LPS clearance may provide a therapeutic approach for sepsis.     

Protective effects of IL-6 blockade in sepsis are linked to reduced C5a receptor expression

IL-6 is known to be an important pro- and anti-inflammatory cytokine, which is up-regulated during sepsis. Our previous work has suggested a role for IL-6 in the up-regulation of C5aR in sepsis. We reported earlier that interception of C5a or C5aR results in improved outcomes in experimental sepsis. Using the cecal ligation/puncture (CLP) model in mice, we now demonstrate that treatment with anti-IL-6 Ab (anti-IL-6) results in significantly improved survival, dependent on the amount of Ab infused. CLP animals showed significantly increased binding of 125I-labeled anti-C5aR to organs when compared to either control mice at 0 h or CLP animals infused with normal rabbit 125I-labeled IgG. Binding of 125I-labeled anti-C5aR to lung, liver, kidney, and heart was significantly decreased in anti-IL-6-treated animals 6 h after CLP. RT-PCR experiments with mRNA isolated from various organs obtained 3, 6, and 12 h after CLP demonstrated increased C5aR mRNA expression during the onset of sepsis, which was greatly suppressed in CLP mice treated with anti-IL-6. These data suggest that IL-6 plays an important role in the increased expression of C5aR in lung, liver, kidney, and heart during the development of sepsis in mice and that interception of IL-6 leads to reduced expression of C5aR and improved survival.     

Effect of penehyclidine hydrochloride on expressions of MAPK in mice with CLP-induced acute lung injury

Penehyclidine hydrochloride (PHC) is a new anticholinergic drug. PHC has been shown to have a good curative effect for sepsis. Mitogen-activated protein kinase (MAPK) has recently been considered to play an important role in sepsis. In this study, the role of MAPK signal pathways in protective effects of PHC preconditioning on acute lung injury in cecal ligation and puncture (CLP)-induced sepsis was investigated. Healthy female mice were randomly divided into 4 groups: sham control, CLP, and 0.3 or 0.45 mg/kg PHC. At 12 h after surgery, arterial blood was drawn for blood gas analysis, and lung tissue samples were collected to examine pulmonary microvascular permeability, IL-6 levels and myeloperoxidase (MPO) activity. MAPK protein expressions were measured using western blot technique. Compared with sham control mice, acute lung injury was induced in CLP group, which was indicated by decreased PaO₂/FiO₂, increased pulmonary microvascular permeability, IL-6 levels and MPO activity. Furthermore, mice’ exposure to CLP induced the increased protein levels of MAPK. Treatment of 0.45 mg/kg PHC markedly improved PaO₂/FiO₂, decreased pulmonary microvascular permeability, IL-6 levels and MPO activity, and inhibited expressions of extracellular signal-regulated kinase (ERK1/2) and p38 MAPK. Taken together, these results suggest that PHC ameliorated acute lung injury through the inhibition of extracellular signal-regulated kinase (ERK1/2) and p38 MAPK activation in septic mice.     

Lactobacillus rhamnosus GG and Bifidobacterium longum Attenuate Lung Injury and Inflammatory Response in Experimental Sepsis

Introduction

Probiotic use to prevent nosocomial gastrointestinal and potentially respiratory tract infections in critical care has shown great promise in recent clinical trials of adult and pediatric patients. Despite well-documented benefits of probiotic use in intestinal disorders, the potential for probiotic treatment to reduce lung injury following infection and shock has not been well explored.

Objective

Evaluate if Lactobacillus rhamnosus GG (LGG) or Bifidobacterium longum (BL) treatment in a weanling mouse model of cecal ligation and puncture (CLP) peritonitis will protect against lung injury.

Methods

3 week-old FVB/N mice were orally gavaged with 200 µl of either LGG, BL or sterile water (vehicle) immediately prior to CLP. Mice were euthanized at 24 h. Lung injury was evaluated via histology and lung neutrophil infiltration was evaluated by myeloperoxidase (MPO) staining. mRNA levels of IL-6, TNF-α, MyD88, TLR-4, TLR-2, NFΚB (p50/p105) and Cox-2 in the lung analyzed via real-time PCR. TNF-α and IL-6 in lung was analyzed via ELISA.

Results

LGG and BL treatment significantly improved lung injury following experimental infection and sepsis and lung neutrophil infiltration was significantly lower than in untreated septic mice. Lung mRNA and protein levels of IL-6 and TNF-α and gene expression of Cox-2 were also significantly reduced in mice receiving LGG or BL treatment. Gene expression of TLR-2, MyD88 and NFΚB (p50/p105) was significantly increased in septic mice compared to shams and decreased in the lung of mice receiving LGG or BL while TLR-4 levels remained unchanged.

Conclusions

Treatment with LGG and BL can reduce lung injury following experimental infection and sepsis and is associated with reduced lung inflammatory cell infiltrate and decreased markers of lung inflammatory response. Probiotic therapy may be a promising intervention to improve clinical lung injury following systemic infection and sepsis.