p38丝裂原活化蛋白激酶信号转导通路在严重烧伤大鼠枯否细胞肿瘤坏死因子α和白细胞介素1β产生中的作用

目的 探讨p38丝裂原活化蛋白激酶(MAPK)信号转导通路在严重烧伤大鼠枯否细胞(KCs)促炎性细胞因子肿瘤坏死因子α(TNF-α)和白细胞介素1β(IL-1β)产生中的作用。方法 健康成年的雄性SD大鼠32只,随机分为：假烫组;假烫 SB203580组;烧伤对照组;烧伤 SB203580组,每组8只。假烫或烧伤24h后分离出肝脏KCs,培养18h后加入50ng／ml的LPS进行刺激,18h后取上清液,用酶联免疫吸附法(ELISA)测定TNF-α和IL-1β的含量,并收集KCs,实时逆转录聚合酶链反应检测KCs内TNF-α和IL-1β mRNA表达的改变,蛋白印迹(Western blot)法检测KCs中p38MAPK和JNK活性的变化。结果 烧伤大鼠分离出的KCs培养上清液中TNF-α和IL-1β含量、KCs中TNF-α和IL-1β mRNA的表达均较假烫组的明显增强,同时KCs中p38 MAPK活性和JNK活性升高,SB203580能显著抑制大鼠KCs上清液中TNF-α和IL-1β含量、KCs中TNF-α和IL-1β mRNA的表达和p38MAPK活性的升高,对JNK活性无影响。结论p38MAPK信号转导通路介导了严重烧伤大鼠KCs促炎性细胞因子TNF-α和IL-1β的产生。     

白细胞介素-1β对原代培养大鼠肝细胞的细胞毒性作用

目的利用原代培养大鼠肝细胞 ,研究白细胞介素 1β(IL 1β)对肝细胞的作用。 方法无菌条件下原位胶原酶灌注Wistar大鼠肝脏分离肝细胞。观察IL 1β对肝细胞释放LDH ,肝细胞增殖(3 H标记的胸腺嘧啶掺入法 )以及肝细胞能量代谢的影响 (细胞内ATP含量和培养液中酮体比KBR)。结果在 6种培养条件下 ,各IL 1β组LDH活性均显著高于对照组 (培养条件Ⅰ～Ⅵ ,各对照组LDH活性分别为 :2 2± 2 ;2 5± 4;18± 5 ;12± 4;15± 5 ;11± 4,各IL 1β组分别为 :36± 3;43± 5 ;34± 6 ;31± 4;31± 5 ;2 2± 3,P值均小于 0 0 5 ) ;在培养条件Ⅱ情况下 ,IL 1β显著减少了原代培养大鼠肝细胞胸腺嘧啶的掺入量〔对照组 :(2 34 5 6± 312 3)Dpm/ 0 2 5× 10 6个细胞 ,IL 1β组 :(15 34 0±2 5 34 )Dpm/0 2 5× 10 6个细胞 ,P <0 0 1)〕 ;在培养条件Ⅳ、Ⅴ、Ⅵ情况下 ,IL 1β显著降低了培养细胞内ATP的含量(培养条件Ⅳ、Ⅴ、Ⅵ ,各对照组细胞内ATP的含量分别为 :10 0± 1 1;11 0± 2 3;11 5± 1 5 ,各IL 1β组分别为 :6 5± 0 5 ;5 9± 1 3;5 6± 1 2 ,P值均小于 0 0 5 ) ;在培养条件Ⅳ、Ⅴ、Ⅵ情况下 ,IL 1β显著降低了KBR(培养条件Ⅳ、Ⅴ、Ⅵ ,各对照组细胞内ATP的含量分别为 :1 0 1± 0 2 1;0 85± 0 13;0     

烟雾吸入性损伤大鼠肺组织丝裂原活化蛋白激酶通路的变化

目的 了解烟雾吸入性损伤大鼠肺组织丝裂原活化蛋白激酶(MAPK)通路及炎性细胞因子含量的变化,探讨其损伤机制. 方法建立密闭舱内烟雾吸入性损伤模型,将30只SD大鼠分为烟雾吸入性损伤后1、6、24、72 h及7 d组,另设正常对照组(6只).取各组大鼠肺组织行病理学观察,检测肺组织匀浆液中肿瘤坏死因子α(TNF-α)、巨噬细胞炎性蛋白2(MIP-2)和白细胞介素1β(IL-1β)含量,用蛋白质印迹法检测肺组织p38MAPK、c-Jun氨基末端激酶(JNK)、细胞外信号调节激酶1/2(ERK1/2)及各酶磷酸化水平.收集大鼠支气管肺泡灌洗液(BALF),检测TNF-α、MIP-2、IL-1β含量并行粒细胞分类、计数. 结果烟雾吸入使大鼠产生急性肺损伤样病理改变.伤后1 h组大鼠肺组织及BALF中TNF-α和IL-1β含量均高于正常对照组(P<0.01).各组肺组织MIP-2水平与正常对照组接近(P>0.05),伤后1 h组BALF中MIP-2水平高于正常对照组(P<0.01).各致伤组p38MAPK、ERK1/2、JNK水平接近正常对照组,但此3种酶的磷酸化水平在伤后不同时相组有高表达.伤后1 h组大鼠BALF粒细胞总数为(0.36±0.08)×106个/L,较正常对照组(0.61±0.09)×106个/L明显减少(P<0.05),伤后7 d组粒细胞总数[(1.71±0.67)×106个/L]却高于正常对照组(P<0.05).伤后6 h～7 d组中性粒细胞数多于正常对照组(P<0.05).伤后1 h组巨噬细胞数少于正常对照组(P<0.05),但6 h～7 d组逐渐增多.各组大鼠淋巴细胞数量接近(P>0.05).结论 密闭舱室内非金属材料燃烧释放的毒性气体能诱导肺组织产生明显的炎性反应,激活细胞MAPK通路中重要激酶的表达,这可能是毒性混合气体导致肺损伤的重要机制之一.     

p,p'-DDE,β-BHC单独及其联合对睾丸Sertoli细胞JNK MAPK信号转导通路机制的研究

目的:研究2,2-双-(对氯苯基)-1,1-二氯乙烯(p,p'-DDE)和β-六氯化苯(β-BHC)单独作用及联合作用对离体培养大鼠睾丸Sertoli细胞c-jun氨基末端激酶(JNK)丝裂原活化蛋白激酶(MAPK)信号转导通路的作用机制。方法:从大鼠睾丸组织中分离Sertoli细胞进行离体原代培养2d,设溶剂(DMSO)为对照组,分别以终浓度为10、30、50μmol/L的p,p'-DDE,β-BHC及二者联合染毒Sertoli细胞24h,采用二步RT-PCR法检测Sertoli细胞JNK、c-junmRNA的表达水平。结果:①染毒24h后,对照组及10、30、50μmol/Lp,p'-DDE组Sertoli细胞JNKmRNA灰度比值分别为0.068±0.001、0.164±0.002、0.207±0.006、0.499±0.017;c-junmRNA灰度比值分别为0.122±0.002、0.157±0.006、0.218±0.007、0.289±0.004,随着p,p'-DDE剂量的增加,JNK、c-junmRNA的表达水平均逐渐升高,且10、30、50μmol/L组与对照组差异存在显著性(P<0.05)。β-BHC及联合染毒各组随着染毒剂量的增大,Sertoli细胞JNK、c-junmRNA表达水平也显著增加,且呈剂量依赖性关系(P<0.05)。②p,p'-DDE、β-BHC二者联合作用与单独作用相比,10μmol/L的p,p'-DDE,β-BHC及二者联合染毒组,JNKmRNA灰度比值分别为0.164±0.002、0.149±0.003、0.178±0.004;c-junmRNA灰度比值分别为0.157±0.006、0.131±0.004、0.172±0.002,联合染毒组JNK、c-junmRNA灰度比值均显著高于两者单独作用且存在显著性差异(JNK:P<0.05;c-jun:P<0.01);30、50μmol/L染毒剂量组JNK、c-junmRNA表达水平联合染毒组也显著高于单独染毒组(JNK:P<0.05,c-jun:P<0.01),而各DMSO对照组之间mRNA表达水平无显著性差异(P>0.05)。结论:p,p'-DDE、β-BHC及二者联合作用于睾丸Sertoli细胞后,JNK及其下游的c-jun基因转录水平均明显升高,且联合作用比单独作用更加明显。     

血管紧张素Ⅱ通过JNK-c-Jun/AP-1信号通路调控系膜细胞转化生长因子β1表达

目的 探讨c-Jun氨基末端激酶(JNK)-c—Jun／活化蛋白(AP)-1信号转导通路在血管紧张素Ⅱ(AngⅡ)诱导的肾小球系膜(MC)细胞转化生长因子β1(TGF—β1)表达中的调控作用。方法 应用核酸酶保护法检测系膜细胞TGF—β1mRNA表达。应用凝胶电泳迁移率(EMSA)、超迁移实验和非放射性激酶活性检测法检测系膜细胞内AP—1活化、AP-1的组成及JNK活性。应用ELISA法检测培养上清中纤连蛋白(FN)。结果 AngⅡ可诱导MC内JNK活化，刺激30min后，JNK活性达到高峰，1h后几乎恢复至正常水平。AngⅡ刺激后MC内AP-1活性显著增强，活化的AP-1主要含有c-Jun和c—Fos亚基。AngⅡ可促进MC表达TGF—βl及分泌FN，抗TGF—β1抗体显著抑制AngⅡ促进的FN分泌。JNK特异性抑制剂SP600125显著抑制AngⅡ诱导AP-1活化、TGF—β1表达及FN分泌。结论 AngⅡ-JNK—c-Jun／AP-1-TGF—β1-FN信号转导通路在肾小球硬化中发挥一定作用，SP600125能部分抑制AngⅡ诱导的AP-1活化、TGF—β1表达及FN的合成，可能具有一定的治疗作用。     

枯否细胞NF-κB 激活对胆源性内毒素血症大鼠肝部分切除后肝细胞再生的影响

目的探讨胆源性内毒素血症(BE)大鼠肝部分切除(PH)后枯否细胞(KCs)核因子-κB(NF-κB))激活对肝细胞再生的影响.方法将Wistar大鼠分为4组(每组72只)N-PH组(正常大鼠70%PH组);BE-PH组(BE大鼠70%PH组);BE-PH 白细胞介素(IL)-10治疗组;BE-PH治疗对照组.检测70%PH后0、1、6、24、48、72h KCs NF-κB 激活、KCs肿瘤坏死因子α(TNFα)mRNA、IL-1βmRNA和IL-6 mRNA表达以及肝细胞溴脱氧核苷尿嘧啶(BrdU)标记.结果 BE-PH组KCs NF-κB活性高于N-PH组(P<0.001),KCs TNFαmRNA、IL-1βmRNA及IL-6 mRNA表达亦明显高于N-PH组,而肝细胞BrdU高峰标记指数(38.82±9.79)低于N-PH组(64.37±13.69)(P<0.01);BE-PHIL-10组KCs NF-κB 活性低于BE-PH组(P<0.01),KCs TNFα、IL-1β及IL-6 mRNA表达减少,而肝细胞BrdU高峰标记指数高于BE-PH组(P<0.05).结论 BE-PH后KCs NF-κB 高水平激活导致KCs TNFαmRNA、IL-1βmRNA及IL-6 mRNA表达增高,从而抑制肝细胞再生,适当调控KCs NF-κB 活性能促进BE-PH后肝细胞再生.     

白介素1β在升主动脉瘤和Debakey Ⅰ型胸主动脉夹层中的表达研究

目的 探讨白介素1β( interleukin-1β,IL-1β)在Debakey Ⅰ型胸主动脉夹层(TAD)和升主动脉瘤(ATAA)中的表达情况.方法 TUNEL染色、免疫组织化学染色、Western blot、实时定量PCR分别检测11例TAD,10例ATAA及7例正常主动脉标本的IL-1β、MMP-9、p38和JNK蛋白及中膜细胞凋亡在主动脉中膜中的表达和定位,并分析IL-1β的表达与中膜平滑肌细胞凋亡、MMP-9、p38和JNK蛋白表达的关系.结果 TAD和ATAA组中膜细胞凋亡较对照组高(P＜0.01).IL-1β的表达在正常组、TAD组、TAA组中逐渐升高(P＜0.01).MMP-9在TAD和ATAA组中的表达较对照组明显升高(P＜0.01).TAD组中,IL-1β与MMP-9和p38的表达呈正相关(P ＜0.01);TAA组中,IL-1β和细胞凋亡呈正相关(P＜0.01).结论 IL-1β在Ⅰ型主动脉夹层和升主动脉瘤中高表达,可能通过上调MMP-9的表达和(或)增加中膜细胞凋亡起作用,作用的信号传导通路可能是p38而非JNK信号转导通路.     

p38丝裂原活化蛋白激酶信号转导通路和核因子-κB/抑制因子κB通路在烧伤后促炎性细胞因子产生中的相互作用

目的探讨烧伤后p38丝裂原活化蛋白激酶(MAPK)信号转导通路和核因子(NF)-κB/抑制因子(I)κB通路在调控细胞因子产生方面的地位及是否存在相互作用。方法人单核细胞株THP-1分为正常血清对照组、烧伤血清组、烧伤血清+SB203580组(p38 MAPK特异性抑制剂)和烧伤血清+PDTC(NF-κB特异性抑制剂)组,每组均实验8次。血清刺激24 h后,酶联免疫吸附法测定上清液中肿瘤坏死因子α(TNF-α)和白细胞介素1β(IL-1β)的含量,蛋白印迹(W estern b lot)法检测THP-1内p38 MAPK的活性和IκBα的表达,凝胶电泳迁移率变化分析法检测THP-1内NF-κB和激活蛋白(AP-1)活性的变化。结果和正常血清相比,烧伤血清刺激后24 h,THP-1上清液中TNF-α和IL-1β的含量均明显上升[分别为(7.30±0.84)ng/m l和(2.20±0.28)ng/m l,P<0.05;(2.88±0.38)ng/m l和(0.81±0.14)ng/m l,P<0.05],p38 MAPK活性升高(4728±582和1291±163,P<0.05),IκBα含量下降(1211±115和2658±318,P<0.05),THP-1中NF-κB活性和AP-1活性均较正常血清显著升高(1636±170和317±32,P<0.05;946±137和361±40,P<0.05),使用SB203580和PDTC均能抑制烧伤血清刺激后THP-1上清液中TNF-α和IL-1β的含量的上升。预先给予SB203580能抑制烧伤血清刺激后THP-1中p38 MAPK和AP-1活性升高,但对IκBα含量和NF-κB活性无显著影响;预先给予PDTC可以防止烧伤血清刺激后THP-1中IκBα含量的下降和NF-κB活性的升高,而对p38 MAPK和AP-1活性无影响。结论在烧伤后全身炎症反应的发生中,p38 MAPK信号转导通路和NF-κB/IκB通路是两个平行和独立的信号转导通路,彼此之间没有直接的联系,共同调节着烧伤后单核细胞TNF-α和IL-1β的产生。     

JNK、p38 MAPK在移植静脉血管重塑过程中的表达研究

目的　研究c Jun氨基末端激酶 (JNK)和p38蛋白激酶 (MAPK)在移植静脉血管重塑过程中的表达。方法　Wistar大鼠 80只 ,建立自体移植静脉模型 ,术后随机分为 6h ,1、3、7,1 4、2 8、4 2、5 6d等 8组 ,于相应时点取材 ,逆转录聚合酶链反应 (RT PCR)检测JNK和p38MAPK的mRNA表达 ,Western蛋白印迹检测JNK和p38的蛋白产物及磷酸化蛋白产物表达 ,原位杂交和免疫组化方法定位mRNA及蛋白产物表达 ,脱氧核苷酸转移酶末端标记法 (TUNEL)检测血管平滑肌细胞 (VSMC)凋亡的变化。结果　移植静脉术后 6h ,JNK和p38的mRNA表达增强 ,在术后 1 4d达到高峰 ,表达值分别为(2 6± 1 0 ) %和 (5 9± 2 6 ) %,与各时点比较差异有统计学意义 (P <0. 0 1 )。JNK、p38的蛋白产物表达在1 4～ 2 8d达高峰 ,在 5 6d时仍维持一定表达量 (1 .4～ 1 . 2 )。原位杂交及免疫组化提示阳性表达多位于移植血管中层或增生内膜中的血管平滑肌细胞 (VSMC) ,p38与凋亡呈正相关 (r =0 . 892 2 ,P <0. 0 1 )。结论　JNK和p38MAPK通路的激活是移植静脉内膜增生以及血管重塑的关键环节 ,可能成为新的治疗靶点。     

丝氨酸/苏氨酸蛋白激酶对肝癌细胞凋亡的促进作用

目的评价丝氨酸/苏氨酸蛋白激酶(HIPK1)促进肿瘤坏死因子(TNF)-α诱导的JNK/p38激活及其对肝癌细胞凋亡的影响。方法Hepa1-6细胞,分别感染重组腺病毒rAd-Lacz-V5(107PFU/孔)和rAd-myc-HIPK1(107PFU/孔)48h,荧光显微镜检测Lacz和HIPK1的蛋白表达,TNF-α处理细胞后Western blot检测JNK/p38激活情况;HIPK1的RNA干扰检测HIPK1在JNK/p38激活中的作用;TNF-α处理病毒感染的Hepa1-6细胞24h,DAPI染色荧光显微镜下了解细胞凋亡情况。结果荧光显微镜下见Lacz和HIPK1蛋白在Hepa1-6细胞中表达效率高;HIPK1组中TNF-α介导的磷酸化型JNK/p38的表达明显高于Lacz组,相反HIPK1的RNA干扰组中TNF-α介导的磷酸化型JNK/p38的表达明显低于对照组;细胞核形态学检测HIPK1组中细胞凋亡率为(30.72±5.67)%,而Lacz组为(9.82±3.41)%,两组间差异有统计学意义(P<0.01)。结论HIPK1促进TNF-α介导的JNK/p38的激活并诱导肝癌细胞Hepa1-6凋亡。     

p38丝裂原活化蛋白激酶在烧伤大鼠急性肺损伤中的作用机制

目的　研究 p38丝裂原活化蛋白激酶 (MAPK)信号转导通路在严重烧伤大鼠肺部促炎细胞因子肿瘤坏死因子α(TNF α)、白细胞介素 1β(IL 1β)产生及肺血管内皮细胞损伤中的作用和相关机制。　方法　健康成年雄性SD大鼠 4 8只 ,随机分为假烫 (A)组、烫伤对照 (B)组和烫伤 p38MAPK抑制剂SB2 0 35 80(C)组 ,每组各 16只。观察烫伤 (以下称烧伤 ) 2 4h后大鼠血清和支气管肺泡灌洗液 (BALF)中TNF α和IL 1β含量、血浆和肺脏微血管vonWillebrand因子 (vWF)含量、肺脏激活蛋白 1(AP 1)活性等指标的改变。　 结果　B组大鼠烧伤后 2 4h血清和BALF中TNF α和IL 1β含量明显增高 ,血浆vWF含量为 (194 .2± 2 8.3) % ,显著高于A组的 (93.2± 14 .3) % (P <0.0 1);肺脏微血管vWF含量的积分值为 1.1± 0 .3,显著低于A组的 3.3± 0 .4 (P <0.0 1);其肺脏AP 1活性上升。C组血清和BALF中TNF α和IL 1β含量、血浆及肺脏微血管vWF含量、肺脏AP 1的活性较B组变化幅度明显偏小。　结论　p38MAPK活化后 ,通过活化转录因子AP 1,介导了严重烧伤后肺脏促炎性细胞因子TNF α和IL 1β的产生和肺血管内皮细胞的损伤     

Anti-apoptotic effect of quercetin: intervention in the JNK- and ERK-mediated apoptotic pathways

BACKGROUND: Bioflavonoid quercetin inhibits hydrogen peroxide (H2O2)-induced apoptosis via intervention in the activator protein 1 (AP-1)-mediated apoptotic pathway. In this report, we investigated molecular events involved in the anti-apoptotic effect of quercetin, focusing especially on its effects on the family of mitogen-activated protein (MAP) kinases. METHODS: Cultured mesangial cells were exposed to H2O2, and activation of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinases (ERKs), and p38 MAP kinase was evaluated in the presence or absence of quercetin. Using pharmacological and genetic inhibitors, the roles for individual MAP kinases in H2O2-induced apoptosis were examined. Involvement of ERKs in the induction and activation of AP-1 was also investigated using Northern blot analysis and a reporter assay. RESULTS: Mesangial cells exposed to H2O2 exhibited rapid phosphorylation of JNK, ERKs, and p38 MAP kinase. Quercetin abrogated the activation of all three MAP kinases in response to H2O2. Pretreatment with MAP kinase kinase inhibitor PD098059 or JNK-c-Jun/AP-1 inhibitor curcumin attenuated the H2O2-induced apoptosis. In contrast, the p38 MAP kinase inhibitor SB203580 did not improve the cell survival. Consistently, transfection with dominant-negative mutants of ERK1 and ERK2 or a dominant-negative mutant of JNK inhibited H2O2-induced apoptosis. Transfection with a dominant-negative p38 MAP kinase did not attenuate the apoptotic process. Inhibition of ERKs by PD098059 suppressed induction of c-fos without affecting early induction of c-jun, leading to attenuated activation of AP-1 in response to H2O2. CONCLUSIONS: These results suggested that (1) activation of JNK and ERKs, but not p38 kinase, is required for the H2O2-induced apoptosis; and (2) suppression of the JNK-c-Jun/AP-1 pathway and the ERK-c-Fos/AP-1 pathway is involved in the anti-apoptotic effect of quercetin.     

Epigallocatechin-3-gallate selectively inhibits interleukin-1beta-induced activation of mitogen activated protein kinase subgroup c-Jun N-terminal kinase in human osteoarthritis chondrocytes.

Activation of mitogen activated protein kinases (MAPK) is a critical event in pro-inflammatory cytokine-induced signaling cascade in synoviocytes and chondrocytes that lead to the production of several mediators of cartilage damage in an arthritic joint. Green tea (Camellia sinensis) is a widely consumed beverage and we earlier showed that polyphenols present in green tea (GTP) inhibit the development of inflammation and cartilage damage in an animal model of arthritis. In this study we evaluated the role of epigallocatechin-3-gallate (EGCG), a green tea polyphenol which mimics its anti-inflammatory effects, in modulating the IL-1beta-induced activation of MAPK's in human chondrocytes. We discovered that EGCG inhibited the IL-1beta-induced phosphorylation of c-Jun N-terminal kinase (JNK) isoforms, accumulation of phospho-c-Jun and DNA binding activity of AP-1 in osteoarthritis (OA) chondrocytes. Also IL-1beta, but not EGCG, induced the expression of JNK p46 without modulating the expression of JNK p54 in OA chondrocytes. In immunecomplex kinase assays, EGCG completely blocked the substrate phosphorylating activity of JNK but not of p38-MAPK. EGCG had no inhibitory effect on the activation of extracellular signal-regulated kinase p44/p42 (ERKp44/p42) or p38-MAPK in OA chondrocytes. EGCG or IL-1beta did not alter the total non-phosphorylated levels of either p38-MAPK or ERKp44/p42 in OA chondrocytes. These are novel findings and indicate that EGCG may be of potential benefit in inhibiting IL-1beta-induced catabolic effects in OA chondrocytes that are dependent on JNK activity.     

Modulation of JNK and p38 stress activated protein kinases in isolated islets of Langerhans: insulin as an autocrine survival signal

OBJECTIVE: The objective of this study was to determine the effects of islet isolation and cytokine exposure on e-JUN NH2 terminal kinase (JNK) and p38 activation and whether insulin or the p38 inhibitor PD169316 could modify the response. SUMMARY BACKGROUND DATA: Islet transplantation exposes the cells of the graft to a variety of stressful stimuli that could promote beta-cell death and lead to graft failure. METHODS: Islets from canine (n = 12) and cadaveric human (n = 6) pancreata were isolated and purified. Islets were cultured in CMRL 1066 with and without 100 ng/ml insulin. The response to cytokine stimulation with tumor necrosis factor (TNF)alpha and IL-1 beta and the p38 inhibitor PD169316 was also observed. Islet lysates were analyzed by Western blotting for total and phosphorylated JNK and p38 content. Apoptosis was assessed by TdT-mediated dUTP nick end labeling (TUNEL) assay and by a specific cell death enzyme-linked immunosorbant assay (ELISA). RESULTS: In unstimulated islets, JNK activity was highest immediately following isolation, declining over 3 days to a low baseline level. The activity of p38 was lowest immediately after isolation, increasing progressively with time. The addition of insulin resulted in a more rapid decline in JNK activity, as opposed to p38, which showed no decrease in phosphorylation in response to insulin. In the cytokine stimulation studies, IL-1 beta stimulated p38 activation in a dose dependent manner, while JNK was relatively unaffected. PD169316 (100 microg/ml) was able to inhibit p38 activation in response to the isolation procedure as well as cytokine stimulation. Apoptotic activity was highest 24 hours after isolation, and was significantly reduced when islets were maintained in insulin-supplemented medium. CONCLUSIONS: Inhibition of the stress-activated protein kinase (SAPK) pathways may be important for the maintenance of islet cell survival following islet isolation for transplantation. This study supports an autocrine role of insulin in this process.