创伤弧菌溶细胞素融合蛋白对小鼠单核巨噬细胞产NO及其合酶的影响

目的 研究创伤弧菌溶细胞素融合蛋白(rVvhA)对小鼠单核-巨噬细胞(J774A.1)产生一氧化氮(NO)和诱导型一氧化氮合酶(iNOS)表达的影响.方法 应用MTT法检测rVvhA对J774A.1增殖的抑制作用;Griess法检测NO含量;RT-PCR和免疫荧光法检测iNOS mRNA和蛋白表达水平.结果 0.8 HU/ml及以上浓度rVvhA可显著抑制J774A.1的增殖;在IFN-γ的辅助作用下,0.4 HU/ml的rVvhA即可诱导J774A.1产生大量NO,显著增加细胞内活性以及iNOS mRNA和蛋白表达水平.结论 rVvhA可诱导巨噬细胞产生NO和iNOS表达,在创伤弧菌的致病机制中具有重要意义.     

问号钩端螺旋体侵入单核-巨噬细胞方式及其吞噬泡形成差异性研究

目的 探讨问号钩端螺旋体(简称钩体)侵入人或鼠单核-巨噬细胞方式及其吞噬泡形成差异性.方法 采用透射电镜观察问号钩体黄疸出血群赖型赖株侵入小鼠单核-巨噬样细胞J774A.1和佛波酯(PMA)激活的人单核细胞THP-1后吞噬泡形成情况.采用免疫荧光联合激光共聚焦显微镜及荧光分光光度仪等方法,观察细胞内吞抑制剂单丹磺酰尸胺(MDC)、氧化酚砷(PAO)阻断及内吞相关网格蛋白抗体封闭前后,J774A.1细胞和PMA激活的THP-1细胞内问号钩体赖株数量的变化.结果 J774A.1细胞内问号钩体存在于吞噬泡内,THP-1细胞内问号钩体无吞噬泡膜包绕.MDC和PAO能以剂量依赖方式抑制J774A.1和THP-1细胞内吞问号钩体,其中10 μmol/L以上MDC和1 μmol/L以上PAO阻断的J774A.1和THP-1细胞内问号钩体数量明显少于未阻断细胞(P＜0.05).网格蛋白抗体封闭后,J774A.1和THP-1细胞内问号钩体数量也明显减少(P＜0.05).结论 问号钩体以网格蛋白依赖性内吞途径侵入人或鼠单核-巨噬细胞.人或鼠单核-巨噬细胞内问号钩体吞噬泡形成有明显差异,这可能是人或鼠感染问号钩体后发病情况不同的原因之一.     

细胞周期及其调控基因对问号钩端螺旋体诱导单核-巨噬细胞凋亡的影响

目的 了解不同细胞周期及其调控基因对问号钩端螺旋体(简称钩体)诱导人或鼠单核-巨噬细胞凋亡的影响.方法 采用细胞周期染色试剂盒及流式细胞仪检测问号钩体黄疸出血群赖型赖株感染前后小鼠单核-巨噬样细胞株J774A.1和人单核细胞株THP-1的细胞周期及其变化.采用细胞周期阻滞剂及流式细胞仪建立细胞周期同步化的J774A.1和THP-1细胞并进行鉴定.采用AnnexinV/PI凋亡检测试剂盒及流式细胞仪检测问号钩体赖株感染后细胞周期同步化与非同步化J774A.1和THP-1细胞早期凋亡、晚期凋亡/坏死率.采用实时荧光定量RT-PCR检测问号钩体赖株感染前后J774A.1和THP-1细胞的细胞周期及凋亡基因p21、p27、p53、c-myc和cycA mRNAs水平变化.结果 未感染钩体的正常J774A.1和THP-1细胞均分别处于G1、S和G2/M期,感染后均以G1期细胞为主,但S期THP-1细胞有所增加,J774A.1细胞则否(P＜0.05).J774A.1和THP-1细胞可分别被不同细胞周期阻滞剂阻滞在G1、S、G2/M或M期.G1期J774A.1和THP-1细胞感染后均无明显的早期凋亡现象,M期细胞早期凋亡、晚期凋亡/坏死率均明显升高(P＜0.05),G1期THP-1细胞晚期凋亡/坏死率明显升高(P＜0.05),J774A.1细胞则否.J774A.1和THP-1细胞感染后,p21 mR-NA水平均明显高于未感染细胞(P＜0.05),J774A.1细胞c-myc和p27 mRNAs水平、THP-1细胞cycAmRNA水平也高于未感染细胞(P＜0.05).结论 不同细胞周期及其调控基因对问号钩体诱导人或鼠单核-巨噬细胞凋亡有明显影响,但存在细胞种类差异性.     

感染细胞内问号钩端螺旋体吞噬泡形成及其与溶酶体的融合

目的了解问号钩端螺旋体（简称钩体）感染宿主细胞后吞噬泡形成、吞噬泡与溶酶体融合及感染细胞超微结构改变。方法用问号钩体黄疸出血群赖型56601株感染小鼠单核巨噬样细胞j774A．1和猴肾成纤维细胞Cos-7。采用透射电镜观察J774A．1细胞和Cos-7细胞胞内钩体吞噬泡的形成及感染细胞超微结构的改变。采用免疫双荧光染色法和激光共聚焦显微镜，观察含钩体吞噬泡与溶酶体融合情况。结果问号钩体56601株感染J774A．1细胞30min、感染Cos-7细胞15min即可在胞浆中发现膜包绕的含钩体吞噬泡，吞噬泡内钩体均保持原有生理弯曲。56601株问号钩体感染Cos-7细胞2h后，钩体吞噬泡膜开始消失，但未发现j774A．1细胞内钩体吞噬泡膜消失的现象。J774A．1细胞内钩体吞噬泡与溶酶体发生共区域化，表明吞噬泡与溶酶体发生融合。J774A．1细胞感染钩体后出现染色质浓缩形成的凋亡小体样结构、细胞空泡变性、线粒体肿胀等超微结构病变，但Cos-7细胞感染钩体后其超微结构基本正常。结论问号钩体感染J774A．1细胞和Cos-7细胞后可迅速形成吞噬泡并可能与钩体Ⅲ型分泌系统产物有关。J774A．1细胞内钩体吞噬泡可与溶酶体发生融合。不同细胞的钩体吞噬泡膜消失及超微结构改变有明显差异。     

猪苓多糖协同卡介苗对巨噬细胞表达CD11b、CD18以及协同刺激分子的影响

目的：了解猪苓多糖协同对巨噬细胞J774 A.1CD11b、CD18及协同刺激分子表达的影响.方法：应用流式细胞术检测猪苓多糖协同卡介苗刺激J774 A.10.5 h、1 h、3 h、6 h、12 h、24 h及48 h后,其CD11b、CD18及协同刺激分子CD86、CD40表达的变化.结果：BCG（50 mg/L）组作用1 h后,J774 A.1 CD11b、CD18的表达高于空白组;联合应用PPS（50 mg/L）组刺激12 h,其CD11b、CD18的表达明显高于BCG组（P＜0.05）.BCG组0.5 h、3 h、12 h、24 h、48 h,其协同刺激分子的表达增高;联合应用PPS协同刺激J774 A.10.5 h、1 h、3 h、6 h,协同刺激分子的表达高于BCG组.结论：卡介苗能提高巨噬细胞CD11b、CD18及协同刺激分子的表达,联合应用猪苓多糖可使其作用增强.     

问号钩端螺旋体在体外诱导细胞凋亡及相关信号通路的研究

目的 了解问号钩端螺旋体诱导不同宿主细胞凋亡的作用及相关胞内信号传导通路.方法 建立问号钩体黄疸出血群赖型赖株小鼠单核-巨噬样细胞J774A.1、人脐静脉内皮细胞EVC304和人Ⅱ型肺泡上皮细胞A549感染模型.采用FITC-Annexin V/PI荧光标记流式细胞术检测细胞凋亡或坏死情况.分别采用荧光比色法和Western blot检测感染的J774A.1细胞caspase-3,-8,-9活性和凋亡相关蛋白FADD(Fas-associated death domain)表达水平.结果 问号钩体赖株感染1～6 h后,36.70%～63.70%的J774A.1细胞可H{现明显的早期凋亡,感染12 h时转变为晚期凋亡或坏死为主(53.68%).78.52%问号钩体赖株感染的A549细胞仪出现晚期凋亡或坏死.问号钩体赖株感染的EVC304细胞无细胞凋亡或坏死现象.感染的J774A.1细胞caspase-3和-8最大活性分别为(1453.41±36.07)和(1402.15±59.09)Fu,是未感染细胞的16.38和29.99倍.感染的J774A.1细胞caspase-9虽略有升高为(89.42±5.08)Fu,但明显低于caspase-3和-8(P<0.001).随着感染时间的延长,感染的J774A.1细胞FADD蛋白表达量逐步增加.结论 问号钩体诱导宿主细胞凋亡的效应町因细胞种类不同而有明显差异,FADD→caspase-8→caspase-3是介导问号钩体感染J774A.1细胞凋亡的主要信号通路.     

猪苓多糖联合卡介苗诱导的细胞外热休克蛋白对巨噬细胞功能的影响

目的 研究猪苓多糖联合卡介苗刺激T24膀胱癌细胞株后,细胞外HSP的表达及其对J774A.1巨噬细胞TLR2、TLR4,胞内钙离子(Ca2+)、一氧化氮(NO)和活性氧(ROS)表达的影响,探讨膀胱内灌注卡介苗治疗浅表性膀胱癌的免疫启动和免疫调节机制.方法 用ELISA的方法检测猪苓多糖和卡介苗联合刺激T24膀胱癌细胞后胞外HSP90、HSP70、HSP60、HSP27的表达,胞外HSP作用于J774A.1巨噬细胞后,用流式细胞术检测J774A.1巨噬细胞表面TLR4和TLR2的表达,应用激光共聚焦扫描技术,检测J774A.1细胞内Ca2+、NO和ROS的动态变化.结果 猪苓多糖和卡介苗联合作用组胞外HSP的表达明显高于猪苓多糖和BCG单独使用组(P＜0.05),48h时胞外HSP的表达至峰值,且胞外HSP70呈优势表达;胞外HSP可上调J774A.1巨噬细胞TLR4的表达(P＜0.05),对J774A.1细胞内Ca2+、NO和ROS有明显的调节作用(P＜0.05).结论卡介苗体外直接刺激人T24膀胱癌细胞后,可表达细胞外HSP90、HSP70、HSP60、HSP27,猪苓多糖和卡介苗联合使用可增加其表达.细胞外HSP对J774巨噬细胞有一定的免疫调节作用.     

巨噬细胞J774A.1外泌体促进结直肠癌细胞系MC38和CT26的增殖和迁移

目的探讨巨噬细胞J774A.1分泌的外泌体对小鼠结直肠癌细胞系MC38和CT26增殖和迁移的影响及作用机制。方法应用流式细胞术对J774A.1细胞进行表型鉴定;应用透射电镜、纳米颗粒跟踪分析(NTA)和Western blot分别检测J774A.1细胞外泌体的形态特征、大小和表面标志物;荧光显微镜下观察MC38和CT26细胞对外泌体的摄取情况;应用CCK8法检测外泌体对MC38和CT26细胞增殖作用的影响;细胞划痕实验检测MC38和CT26细胞的迁移能力;Western blot检测增殖相关通路的磷酸化蛋白p-MEK1/2和p-ERK1/2的表达变化。结果 J774A.1细胞为表达细胞表面标志分子CD68和CD206的M2型巨噬细胞。J774A.1细胞的外泌体均能被结直肠癌细胞MC38和CT26摄取,而且能够促进它们增殖(P0.05)、迁移及MEK-ERK信号通路激活。结论巨噬细胞J774A.1的外泌体能够促进结直肠癌细胞系MC38和CT26的增殖及迁移,这可能与MEK-ERK信号通路的磷酸化增加有关。     

猪苓多糖/卡介苗诱导的热休克蛋白对巨噬细胞表面分子的影响

目的:观察猪苓多糖/卡介苗诱导T24膀胱癌细胞产生的细胞外热休克蛋白对J774A.1巨噬细胞TLR、共刺激分子、粘附分子、活化分子表达的影响,探讨猪苓多糖/卡介苗灌注治疗膀胱癌的天然免疫启动机制.方法:(1)ELISA检测猪苓多糖/卡介苗与T24膀胱癌细胞共培养上清中HSP90、HSP70、HSP60、HSP27的表达.(2)流式细胞术检测含HSP共培养上清(eHSP)对小鼠J774A.1巨噬细胞表面分子CD14、TLR2/4、MHCⅠ/Ⅱ;活化分子CD25;共刺激分子CD80、CD86、CD40;粘附分子CD44、CD62L、CD11b、CD18表达的影响.(3)用流式细胞术检测TLR4/MD2抗体复合物阻断J774A.1巨噬细胞表面TLR4后,eHSP对其表面分子MHCⅠ/Ⅱ、CD25、CD80、CD86、CD40、CD44、CD62L、CD11b、CD18的表达.结果:(1)猪苓多糖/卡介苗诱导T24膀胱癌细胞产生的热休克蛋白呈剂量和时间依赖性,猪苓多糖(2 mg/ml)和卡介苗(250 μg/ml)作用48小时时HSP的表达至峰值,其中HSP70呈优势表达;(2)含HSP的共培养上清可上调J774A.1巨噬细胞TLR4、MHCⅠ、CD86、CD40、CD25分子的表达,增强粘附分子CD44、CD62L荧光强度;(3)含HSP的共培养上清作用于用TLR4/MD2阻断后的巨噬细胞,其表面分子CD86、MHCⅠ、CD40、CD25的表达降低.结论:猪苓多糖/卡介苗可诱导T24膀胱癌细胞产生危险信号热休克蛋白,并且热休克蛋白可通过激活小鼠J774A.1巨噬细胞TLR4信号通路,上调其表面分子的表达,启动抗膀胱癌天然免疫应答.     

钩端螺旋体溶血素Sph2表达模式及诱导巨噬细胞和肝细胞凋亡活性

目的 了解问号钩端螺旋体(简称钩体)感染细胞前后sph2基因表达水平变化,确定鞘磷脂酶类溶血素Sph2及诱导细胞凋亡的活性.方法 采用PCR从黄疸出血群赖型赖株钩体基因组DNA中扩增全长sph2基因片段,T-A克隆后测序.构建sph2基因原核表达系统,采用SDS-PAGE检查重组Sph2(rSph2)的表达情况,Ni-NTA亲和层析法提纯rSph2.采用绵羊血平板溶血试验及血红蛋白分光光度法测定rSph2的溶血活性.采用流式细胞术检测rSph2诱导小鼠单核-巨噬样细胞株J774A.1和肝细胞株IAR20凋亡的活性,实时荧光定量PCR检测赖株钩体感染J774A.1和IAR20细胞前后sph2基因mRNA水平变化.结果 与GenBank中sph2基因比较,所克隆的sph2基因序列相似性为100%.所构建的原核表达系统能高效表达rSph2.rSph2以浓度依赖方式溶解绵羊红细胞.10 μg/ml rSph2可诱导J774A.1和IAR20细胞凋亡,凋亡率峰值分别为23.96%和32.92%.赖株钩体感染J774A.1和IAR20细胞后0.5～2 h内sph2基因mRNA水平显著升高,2 h后mRNA水平迅速下降.结论 钩体sph2基因呈宿主细胞接触式瞬时表达.rSph2有溶解绵羊红细胞及诱导巨噬细胞和肝细胞凋亡的活性,因而Sph2是钩体致病过程中重要的毒力因子.     

Co-culture supernatants from Vibrio vulnificus-infected INT-407 cells induce IL-8 production in intestinal epithelial cells: crucial role of V. vulnificus rtxE

In a previous study, we reported that a gene mutation of repeat in toxin E (RtxE), a transporter of cytotoxic factors, resulted in a significant impairment of epithelial cell cytotoxicity in Vibrio vulnificus, and that the expression of the rtxE gene was induced by the exposure to the host cells. In this study, we evaluated and compared the effects of co-culture supernatants from V. vulnificus-infected INT-407 cells and either the V. vulnificus wild-type or rtxE mutant on the production of interleukin (IL)-8, a pro-inflammatory cytokine, as well as its underlying mechanisms in human intestinal epithelial cells. INT-407 cells were co-cultured with the wild-type V. vulnificus or the rtxE mutant strain to obtain the conditioned supernatants. IL-8 production and nuclear factor (NF)-κB activation from the INT-407 cells treated with each supernatant, were investigated. The co-culture supernatants from the rtxE mutant V. vulnificus-infected INT-407 cells significantly induced lower levels of IL-8 production and promoter activation, NF-κB DNA binding activity, and NF-κB minimal promoter activation in human intestinal epithelial cells, than those from the wild-type V. vulnificus-infected INT-407 cells. Importantly, the reduced IL-8 production and NF-κB activity of the V. vulnificus rtxE mutant, were restored by co-culture supernatants from the rtxE-complemented V. vulnificus. On the whole, these results show that the rtxE gene of V. vulnificus performs a critical role in the secretion of factors from bacteria and host cells, which are involved in IL-8 production via the NF-κB activation pathway in host cells.     

Comparative analysis of proteins in the culture supernatants of human intestinal epithelial cells infected with the wild-type and rtxE mutant of Vibrio vulnificus

Bacterial virulence factors and secreted extracellular proteins from damaged host cells following infection have been recognized as key mediators in the pathophysiological alterations observed in septic shock, and have also been shown to have a synergistic influence on bacterial pathogenicity. We hypothesized that during infections, virulence factors as well as host-shed proteins may synergistically influence aspects of the pathogenicity of V. vulnificus, such as primary septic shock and overproduction of proinflammatory cytokines. However, virulence factors and host-derived proteins have yet to be clearly evaluated during V. vulnificus infection. In this study, we analyzed and compared the proteins in conditioned supernatants generated from co-cultures of host cells and either wild-type or rtxE mutant V. vulnificus using LC-QTOF-MS/MS analysis. In a previous study, we determined that the culture supernatants of the rtxE mutant V. vulnificus-infected INT-407 cells induced significantly lower levels of IL-8 production from human intestinal epithelial cells than did the culture supernatants of wild-type V. vulnificus-infected INT-407 cells. LC-QTOF-MS/MS analysis results demonstrated that levels of proteins such as HSP90 α/β, 14-3-3 γ, PRX II, hnRNP K, β-actin, α-tubulin and V. vulnificus flagellin were significantly lower in the culture supernatants of rtxE mutant V. vulnificus-infected INT-407 cells than in the culture supernatants of wild-type V. vulnificus-infected INT-407 cells. These results demonstrate that V. vulnificus RTX toxins acting via rtxE, a transporter of virulence factors, play a very important role in the pathogenesis of V. vulnificus, as well as in its initial role in inducing pathogenic mediators from host cells.     

Csk overexpression reduces several monokines and nitric oxide productions but enhances prostaglandin E2 production in response to lipopolysaccharide in the macrophage cell line J774A.1

The catalytic activity of src-family protein tyrosine kinases (src-PTK) is suppressed when a C-terminal tyrosine is phosphorylated by an intracellular PTK, C-terminal Src kinase (Csk). In the present report, to study the regulatory functions of the Csk in cells of monocyte/macrophage lineage, we transfected a eukaryotic expression vector containing rat csk cDNA in a macrophage cell line, J774A.1, and examined alterations of the response to lipopolysaccharide (LPS) in the transfectants which overexpressed Csk. Csk overexpression resulted primarily in a down-regulation of Fgr activity, an src-PTK expressed in J774A.1, and hyperphosphorylation of several cellular proteins of 35, 57, 66, 97 and 120–130 kDa. Furthermore, in these Csk transfectants, production of interleukin (IL)-1α, IL-6, tumor necrosis factor-α, and nitric oxide (NO) following LPS stimulation were reduced compared with those in parental J774A.1 or J774A.1 transfected with the vector alone. The extent of reduction paralleled the amounts of Csk proteins expressed in the Csk-transfected J774A.1. The reduced NO production in these cells was associated with low levels of mRNA of inducible NO synthetase. On the other hand, an enhancement of prostaglandin E₂ production was observed in the Csk-transfected J774A.1 cells upon stimulation with LPS, which appeared to result from the high level of prostaglandin-H synthetase in the transfectants. The present findings indicate that overexpression of Csk has differential effects on the regulation of production of chemical mediators and monokines, probably via modulation of signal transduction downstream of LPS-mediated signals.     

NLRP3炎症小体活化促进上皮细胞焦亡诱导变应性鼻炎

目的 研究NLRP3炎症小体激活在变异性鼻炎的发生发展中的作用,并试图探讨其潜在的机制.方法 利用野生型(wide-type,WT)和NLRP3基因敲除(knock out,KO)小鼠构建卵清蛋白(ovalbumin,OVA)诱导的变异性鼻炎模型.按照体质量将小鼠随机分为4组:WT、WT-OVA、NLRP3 KO、NL...     

rVvhA诱导小鼠单核巨噬细胞凋亡的作用及其机制

目的 研究重组创伤弧菌溶细胞素(rVvhA)诱导小鼠单核巨噬细胞(J774A.1)凋亡的作用及机制.方法 MTT法、电子透射电镜、流式细胞仪结合Annexin V-PI标记法、线粒体膜电位和cagpase活性检测等方法测定rVvhA诱导J774A.1凋亡的作用.结果 MTT结果显示rVvhA能够抑制J774A.1生长.2.0溶血单位(HU)/ml和3.0 HU/ml的rVvhA作用J774A.18 h后,透射电镜观察细胞和线粒体形态发生凋亡改变;流式细胞仪检测凋亡率分别为(7.80±0.62)%、(12.33±0.12)%,均高于正常组(3.07±0.67)%;线粒体膜电位也下降,流式细胞仪结果显示绿色荧光率分别是9.8%、39.2%.其中3.0 HU/ml rVvhA作用组,caspage-3、9活性增加,并且具有时间依赖性,而cagpage-8活性没有明显改变.3.0HU/ml rVvhA加caspage-3抑制剂(Ac-DEVD-FMK)或caspase-9抑制剂(Ac-LEHD-FMK)的凋亡率与3.0 HU/ml rVvhA作用组相比都降低,分别为(6.23±3.95)%、(9.60±3.14)%;同时cagpage-3、9活性也下降.结论 rVvhA具有诱导J774A.1凋亡的生物学活性;其机制可能与依赖cagpase的线粒体途径有关.     

Cytotoxicity of, and innate immune response to, size-controlled polypyrrole nanoparticles in mammalian cells

Monodisperse polypyrrole (PPy) nanoparticles with five different diameters (20, 40, 60, 80, and 100?nm) were fabricated via chemical oxidation polymerization in order to evaluate size-dependent cytotoxicity. The cellular uptake of PPy nanoparticles in human lung fibroblasts (IMR90) and mouse alveolar macrophages (J774A.1) was observed by transmission electron microscopy. The nanoparticles were internalized into the IMR90 via endocytosis. In the J774A.1, the nanoparticles were entered via phagocytosis and endocytosis. Endocytosed nanoparticles were transported to lysosome via endosome-network. The cytotoxicity and innate immune response of PPy-treated cells were systematically investigated by viability assay, oxidative stress, apoptosis/necrosis, and expression of costimulatory molecules. The viability, oxidative stress, and apoptosis/necrosis of PPy-treated cells revealed size- and dose-dependency. Because of phagocytosis, PPy treatment had more adverse effects on the J774A.1 than the IMR90. Innate immune response of PPy-treated macrophages was measured by the expression of costimulatory molecules on surface of the cells. The expression of costimulatory molecules involved in Th1 response (CD40 and CD80) was lightly up-regulated and the other costimulatory molecule related in Th2 response (CD86) was less expressed than a negative control. These findings may provide better nanotoxicological information of polymer nanomaterials, and support the further development of PPy nanoparticles in bioelectronic applications.     

Role of Surfactant Protein D in Experimental Otitis Media

Surfactant protein D (SP-D) is a C-type collectin and plays an important role in innate immunity and homeostasis in the lung. This study studied SP-D role in the nontypeable Haemophilus influenzae (NTHi)-induced otitis media (OM) mouse model. Wild-type C57BL/6 (WT) and SP-D knockout (KO) mice were used in this study. Mice were injected in the middle ear (ME) with 5 μL of NTHi bacterial solution (3.5 × 10⁵ CFU/ear) or with the same volume of sterile saline (control). Mice were sacrificed at 3 time points, days 1, 3, and 7, after treatment. We found SP-D expression in the Eustachian tube (ET) and ME mucosa of WT mice but not in SP-D KO mice. After infection, SP-D KO mice showed more intense inflammatory changes evidenced by the increased mucosal thickness and inflammatory cell infiltration in the ME and ET compared to WT mice (p < 0.05). Increased bacterial colony-forming units and cytokine (IL-6 and IL-1β) levels in the ear washing fluid of infected SP-D KO mice were compared to infected WT mice. Molecular analysis revealed higher levels of NF-κB and NLRP3 activation in infected SP-D KO compared to WT mice (p < 0.05). In vitro studies demonstrated that SP-D significantly induced NTHi bacterial aggregation and enhanced bacterial phagocytosis by macrophages (p < 0.05). Furthermore, human ME epithelial cells showed a dose-dependent increased expression of NLRP3 and SP-D proteins after LPS treatment. We conclude that SP-D plays a critical role in innate immunity and disease resolution through enhancing host defense and regulating inflammatory NF-κB and NLRP3 activation in experimental OM mice.     

Group B streptococcus-induced nitric oxide production in murine macrophages is CR3 (CD11b/CD18) dependent.

Nitric oxide (NO) is produced by murine macrophages in response to cytokines and/or gram-negative bacterial lipopolysaccharide. NO induction by gram-positive bacteria such as group B streptococci (GBS), the major etiologic agents of neonatal pneumonia and meningitis, has received little study. GBS as well as two other gram-positive bacterial species, Staphylococcus aureus and Staphylococcus epidermidis, were found to stimulate NO production in thioglycolate-elicited murine macrophages and in the mouse macrophage cell line J774A.1 in the presence of gamma interferon. Serotype Ia and III GBS were both stimulatory, as were asialo- and type antigen-deficient mutant strains of type III GBS. NO production was dose dependent, inhibitable by L-arginine analogs, and unaffected by polymyxin B. Since phagocytosis by murine and human phagocytes of GBS is dependent on complement receptor type 3 (CR3), the role of CR3 in the NO response to GBS was tested in the CR3-deficient myelomonocytic cell line WEHI-3. GBS did not induce NO, whereas S. aureus or lipopolysaccharide did induce NO in WEHI-3 cells. S. epidermidis, whose nonopsonic phagocytosis is also CR3 dependent, failed to induce NO in WEHI-3 cells. Monoclonal anti-CR3 (anti-CD11b or anti-CD18) in the presence of interferon also induced NO production in thioglycolate-elicited macrophages and in J774A.1 cells but not in WEHI-3 cells. This evidence suggests that ligated CR3 and gamma interferon act synergistically to induce NO production and that CR3 mediates the GBS-induced signal for NO production in interferon-treated macrophages.