Maturation of Normal & Sensitized Airway Contractility

儿童时期哮喘患病率较高，早期呼吸道损伤可能会影响哮喘的表现 在成年人身上。几个物种的呼吸道反应性从胎儿生命和出生期间的最低水平增加到 在几天到几周内达到相当高的水平。我们已经发现了磷酸化的关键和平行作用 肌球蛋白轻链激酶(MLCK)对肌球蛋白轻链(MLC20)的作用及其机械阻力的降低 3周龄幼年儿童正常增大的气道平滑肌缩短 豚鼠和新生儿致敏后成人的免疫增强型缩短。最大力 世代不随成熟期和随后的敏化而变化。根据我们的结果：ASM缩短 从青春期到成年期下降，而对缩短RSI的内部抵抗力和被动僵硬 肌肉的增加。MLCK水平和MLC20的磷酸化水平平行下降。在预赛中 新生儿致敏可增加ASM缩短和MLCK含量，降低RSI。 仅限成人ASM。在该应用中，这些发现被集成到一种新的假设机制中，该机制 反映了一种新的范式，在正常的非新生儿青少年和 在新生儿时期就已经致敏的成人。这一范式表明，细胞骨架的变化 有助于缩短的基质与促进磷酸化的那些因素具有类似的重要性 肌球蛋白轻链。这也表明，呼吸道高反应性可能有其起源(因此 需要干预)在生命早期。具体目标是：1.确定MLCK是否增加 内容物对正常青少年和成人ASM缩短的增加起着关键的调节作用 像新生儿一样敏感。为了确定FAST亚型SM1B和SM1B的含量是否增加 肌球蛋白重链SM2B增加ASM缩短。2.确定基因和蛋白质的调控 MLCK的表达在发育和新生儿致敏后的变化。3.确定是否 在正常的青少年气管和新生儿致敏的成人中，气管缩短增加与 被动的机械性能，降低了对缩短的内部阻力。以确定是否 中间细丝结蛋白和波形蛋白的含量/磷酸化在体内起作用 对呼吸道平滑肌缩短的抵抗。

Asthma prevalence is greater during childhood and early airway insults may affect the expression of asthma in adults. Airway reactivity in several species increases from minimal during fetal life and birth to a substantial level in a few days to weeks. We have discovered key and parallel roles for the phosphorylation of myosin light chain (MLC20) by myosin light chain kinase (MLCK) and the reduced mechanical opposition to shortening in the normally augmented shortening of airway smooth muscle (ASM) in 3 week old juvenile guinea pigs and immune-augmented shortening in adults following neonatal sensitization. Maximal force generation is unchanged with maturation and following sensitization. Based on our results: ASM shortening declines from juveniles to adulthood while the internal resistance to shortening Rsi and the passive stiffness of the muscle increase. MLCK levels and the phosphorylation of MLC20 decline in parallel. In preliminary experiments neonatal sensitization increases ASM shortening and MLCK content and decreases the Rsi of ADULT ASM only. In this application, these findings are integrated into a novel hypothetical mechanism that relfects a NEW PARADIGM for augmented smooth muscle shortening in normal non-neonatal juveniles and in adults previously sensitized as neonates. This paradigm suggests that changes in the cytoskeleton matrix to facilitate shortening are of similar importance to those factors that facilitate the phosphorylation of myosin light chain. It also suggests that airway hyperresponsiveness may have its origins (and thus the need for intervention) early in life. The specific aims are: 1. To determine whether or not increased MLCK content plays a key regulatory role in the increased ASM shortening in normal juvenile trachealis and adults sensitized as newborns. To determine whether or not the increased content of the fast isoforms SM1B and SM2B of myosin heavy chain increases ASM shortening. 2. To determine the genetic and protein regulation of MLCK expression with development and following neonatal sensitization. 3. To determine whether the increased shortening in normal juvenile trachealis and in adults sensitized as newborns is associated with passive mechanical properties that reduce the internal resistance to shortening. To determine whether the content/phosphorylation of the intermediate filaments desmin and vimentin plays a role in the internal resistance to shortening of airway smooth muscle.