Martins Joilson O, Wittlin Beatriz M, Anger Denise B C, Martins Daniel O, Sannomiya Paulina, Jancar Sonia
Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.
Cell Physiol Biochem. 2010;26(4-5):739-48. doi: 10.1159/000322341. Epub 2010 Oct 29.
Allergic lung inflammation is impaired in diabetic rats and is restored by insulin treatment. In the present study we investigated the effect of insulin on the signaling pathways triggered by allergic inflammation in the lung and the release of selected mediators.
Diabetic male Wistar rats (alloxan, 42 mg/kg, i.v., 10 days) and matching controls were sensitized by s.c. injections of ovalbumin (OA) in aluminium hydroxide, 14 days before OA (1 mg/0.4 ml) or saline intratracheal challenge. A group of diabetic rats were treated with neutral protamine Hagedorn insulin (NPH, 4 IU, s.c.), 2 h before the OA challenge. Six hours after the challenge, bronchoalveolar lavage (BAL) was performed for mediator release and lung tissue was homogenized for Western blotting analysis of signaling pathways.
Relative to non-diabetic rats, the diabetic rats exhibited a significant reduction in OA-induced phosphorylation of the extracellular signal-regulated kinase (ERK, 59%), p38 (53%), protein kinase B (Akt, 46%), protein kinase C (PKC)-α (63%) and PKC-δ (38%) in lung homogenates following the antigen challenge. Activation of the NF-κB p65 subunit and phosphorylation of IκBα were almost suppressed in diabetic rats. Reduced expression of inducible nitric oxide synthase (iNOS, 32%) and cyclooxygenase-2 (COX-2, 46%) in the lung homogenates was also observed. The BAL concentration of prostaglandin (PG)-E(2), nitric oxide (NO) and interleukin (IL)-6 was reduced in diabetic rats (74%, 44% and 65%, respectively), whereas the cytokine-induced neutrophil chemoattractant (CINC)-2 concentration was not different from the control animals. Treatment of diabetic rats with insulin completely or partially restored all of these parameters. This protocol of insulin treatment only partially reduced the blood glucose levels.
The data presented show that insulin regulates MAPK, PI3K, PKC and NF-κB pathways, the expression of the inducible enzymes iNOS and COX-2, and the levels of NO, PGE(2) and IL-6 in the early phase of allergic lung inflammation in diabetic rats. It is suggested that insulin is required for optimal transduction of the intracellular signals that follow allergic stimulation.
糖尿病大鼠的过敏性肺部炎症受损，胰岛素治疗可使其恢复。在本研究中，我们调查了胰岛素对肺部过敏性炎症触发的信号通路以及特定介质释放的影响。
糖尿病雄性Wistar大鼠（用42 mg/kg四氧嘧啶静脉注射，持续10天）和匹配的对照大鼠，在经气管内给予卵清蛋白（OA，1 mg/0.4 ml）或生理盐水激发前14天，通过皮下注射氢氧化铝佐剂卵清蛋白进行致敏。一组糖尿病大鼠在OA激发前2小时接受中性鱼精蛋白锌胰岛素（NPH，4 IU，皮下注射）治疗。激发后6小时，进行支气管肺泡灌洗（BAL）以检测介质释放，并将肺组织匀浆用于信号通路的蛋白质印迹分析。
与非糖尿病大鼠相比，糖尿病大鼠在抗原激发后肺匀浆中OA诱导的细胞外信号调节激酶（ERK，降低59%）、p38（降低53%）、蛋白激酶B（Akt，降低46%）、蛋白激酶C（PKC）-α（降低63%）和PKC-δ（降低38%）的磷酸化显著降低。糖尿病大鼠中NF-κB p65亚基的激活和IκBα的磷酸化几乎受到抑制。在肺匀浆中还观察到诱导型一氧化氮合酶（iNOS，降低32%）和环氧化酶-2（COX-2，降低46%）的表达减少。糖尿病大鼠支气管肺泡灌洗液中前列腺素（PG）-E2、一氧化氮（NO）和白细胞介素（IL）-6的浓度降低（分别降低74%、44%和65%），而细胞因子诱导的中性粒细胞趋化因子（CINC）-2浓度与对照动物无差异。用胰岛素治疗糖尿病大鼠可完全或部分恢复所有这些参数。该胰岛素治疗方案仅部分降低了血糖水平。
所呈现的数据表明，胰岛素在糖尿病大鼠过敏性肺部炎症的早期阶段调节丝裂原活化蛋白激酶（MAPK）、磷脂酰肌醇-3激酶（PI3K）、蛋白激酶C（PKC）和核因子κB（NF-κB）信号通路、诱导型酶iNOS和COX-2的表达以及NO、PGE2和IL-6的水平。提示胰岛素是过敏性刺激后细胞内信号最佳转导所必需的。
