Asthma
Asthma comes from the Greek word for “panting”, which makes sense because it causes chronic inflammation of the airways, making them narrow and more difficult to breathe through. People with asthma can have asthma exacerbation or asthma attacks, which are usually triggered by something in the environment which causes immune cells to generate inflammation in the lungs which can make them even narrower and potentially be life-threatening. So, if we take a look at the lungs, you’ve got the trachea, which branches off into right and left bronchi, and then continues to branch into thousands of bronchioles.In the bronchioles you’ve got the lumen, the mucosa, which includes the inner lining of epithelial cells, as well as the lamina propria, and the submucosa which is where the smooth muscle lives. The molecular pathway that leads to asthma is actually pretty complex but it is often initiated by an environmental trigger. In asthma there is often an excessive reaction from type 2 helper cells or Th2 cells against specific allergens. Th2 cells, are an immune cell subtype, which are known to be involved in asthma, as well as atopic dermatitis, and allergic rhinitis, making up what’s called the atopic triad. What can happen with asthma is allergens from environmental triggers, like cigarette smoke, are picked up by dendritic cells which present them to a Th2 cell which produce cytokines like IL-4 and IL-5 leading to a number of features of asthma.
哮喘来自希腊语中的“喘气”，这也讲得通，因为它会引起呼吸道的慢性炎症，使呼吸道狭窄，引起呼吸困难。患有哮喘的人可能会有哮喘恶化或哮喘发作，这些疾病通常由环境因素触发，导致免疫细胞产生炎症，从而使其更加狭窄，甚至可能危及生命。所以，如果我们看一下肺，这是气管，它会分支到右和左支气管，然后继续延伸到成千上万的细支气管。在细支气管内，有腔体，粘膜，包括上皮细胞的内层、固有层、粘膜下层，也就是平滑肌所在的地方。导致哮喘的分子途径实际上相当复杂，但通常是由环境引发的。在哮喘中，2型辅助细胞或Th2细胞会对特定过敏原反应过度。Th2细胞，是一种免疫细胞亚型，已知会参与哮喘、特应性皮炎和过敏性性鼻炎，构成了所谓的变异性三体。哮喘是由环境引发的过敏原引起的，比如香烟烟雾，是由树突细胞提呈到Th2细胞中，产生细胞因子IL-4和IL-5，从而导致哮喘的许多特征。
For example, IL-4 leads the production of IgE antibodies which coat mast cells and stimulate them to release granules containing things like histamines, leukotrienes and prostaglandins. IL-5, on the other hand, activates eosinophils which promote an immune response by releasing more cytokines and leukotrienes.In this case, since IgE antibodies are being produced this is an example of a Type 1 hypersensitivity reaction.This leads to two series of events. Early on, minutes after the exposure to the allergen,smooth muscle around the bronchioles start to spasms and there is increased mucus secretion.This narrows the airways making it difficult to breathe, and this is why asthma is considered to be a type of obstructive pulmonary disease.There is also an increase in vascular permeability and and recruitment of additional immune cells from the blood. So, a few hours after exposure, these immune cells, particularly eosinophils, release chemical mediators that physically damage the endothelium of the lungs. Initially these inflammatory changes are completely reversible, but over the years irreversible changes start to take place—edema, scarring, and fibrosis build up, leading to thickening of the epithelial basement membrane, which permanently reduces the airway diameter.
例如，IL-4导致了IgE抗体的产生，覆盖在肥大细胞表面并刺激它们释放含有像组胺、白三烯和前列腺素等物质的颗粒。另一方面，IL-5激活嗜酸性粒细胞，通过释放更多的细胞因子和白三烯来促进免疫反应。在这种情况下，由于IgE抗体正在产生，这是1型超敏反应的一个例子。这导致了两件事。早期，在接触过敏原的几分钟后，细支气管周围的平滑肌开始痉挛，粘液分泌增多。呼吸道变窄，难以呼吸，这就是为什么哮喘被认为是一种阻塞性肺病。血管通透性也在增加，血液中额外的免疫细胞也参与进来。因此，接触后的几个小时，这些免疫细胞，尤其是嗜酸性粒细胞，释放出化学介质，损害肺部的内皮细胞。最初这些炎症变化是完全可逆的，但是随时间进展，不可逆的变化开始发生，水肿，瘢痕，纤维化，导致上皮基底膜增厚，从而永久性地减少气道直径。
Although the specific causes of asthma are ultimately unknown, it’s thought to be caused by a combination of genetic and environmental factors, since certain genes have been identified that increase the risk of developing asthma and having a family history of asthma seems to increase risk as well. For environmental factors, there’s the hygiene hypothesis, which suggests that reduced early immune-system exposure to bacteria and viruses which might actually increase the risk of later developing asthma, possibly by altering the overall proportion of immune cell subtypes. In general, causes of childhood asthma diagnosed before age 12 are thought to be due to a stronger genetic influence, whereas later onset asthma is more likely to be largely due to environmental factors.
尽管哮喘病的具体病因尚不清楚，但它被认为由遗传因素和环境因素共同引起的，因为某些基因已经被确认会增加患哮喘的风险，而且哮喘家族史似乎也增加了患病风险。对于环境因素，有一个卫生假说，认为早期免疫系统没有接触过细菌和病毒，事实上，可能会增加日后患哮喘的风险，可能是通过改变免疫细胞亚型的整体比例。一般来说，12岁之前被诊断出哮喘的原因是由于遗传因素影响更大，而后来的哮喘发作更可能是环境因素造成的。
Now, the triggering substance that leads to the asthma attack can differ from person to person, but some common ones include air pollution, like cigarette smoke and car exhaust, as well as allergens like dust, pet dander, cockroaches, and mold. Medications like aspirin and beta-blockers have also been known to trigger symptoms in some individuals with asthma. That said, symptoms of asthma include coughing, a feeling of chest tightness, dyspnea, or difficulty breathing, and wheezing, or a high-pitched whistling sound that usually happens during exhalation. Occasionally in the sputum there might curschmann spirals, which are spiral shaped mucus plugs which are basically elongated mucous casts from small bronchi of people with bronchial asthma. Mucus plugs can be particularly dangerous because they not only block exchange of air, but they also block inhaled medications from getting to the site of inflammation. The mucus may also contain Charcot-Leyden crystals which are shaped like needles and are formed by the breakdown of eosinophils.
导致哮喘发作的物质，人与人不同，但一些常见的包括空气污染，如香烟烟雾和汽车尾气，以及灰尘、宠物皮屑、蟑螂和霉菌等过敏原。阿司匹林和β受体阻滞剂等药物在一些哮喘病例中也会引发症状。也就是说，哮喘的症状包括咳嗽、胸闷、呼吸困难、喘息、呼气时高调吹哨音，偶尔在痰中可能会有库什曼螺旋体，也就是螺旋形的粘液栓，基本是支气管哮喘患者的小支气管塑成的细长粘液。粘液栓塞是非常危险的，因为它们不仅阻断了空气的交换，而且还阻止了吸入药物进入炎症部位。黏液中也可能含有一些形状像针的Charcot-Leyden晶体，由嗜酸性粒细胞分解形成。
Now, asthma can be classified according to the frequency of symptoms, in particular night-time and early morning symptoms, the FEV1, or forced expiratory volume in one second, the PEFR,or peak expiratory flow rates, both of which measure the amount of obstruction in the airways,and finally how often a person is using asthma medication to help with the symptoms. From least to most severe, the types of asthma are intermittent asthma, mild persistent asthma, moderate persistent asthma, and finally severe persistent asthma. While there is no cure for asthma, there are treatments available that can manage the symptoms and prevent the development of an asthma attack.
现在，哮喘可分类根据症状的频率,尤其是夜间和清晨症状，FEV1，或一秒钟用力呼气量，PEFR或呼气流速峰值，这两种可以衡量气道阻塞程度，最后是一个人多久时间用哮喘药物控制症状。从最小到最严重，哮喘的类型有间歇性哮喘，轻度持续性哮喘，中度持续性哮喘，最后是严重的持续性哮喘。虽然没有治疗哮喘的方法，但是有治疗方法可以控制症状，防止哮喘发作。
First, people with asthma should avoid or minimize contact with triggering substances by vacuuming, removing carpets and rugs, and changing the environmental conditions, like for example drying out a room in the case of molds that grow well in moist areas. There are also a number of medications that can reduce the symptoms of asthma. Bronchodilators such as short-acting beta-adrenoceptor agonists and anticholinergic medications are often administered through emergency inhalers. These fast-acting medications cause the smooth muscles in the lungs to relax and therefore dilate the airways, opening them up so that a person can breath. Individuals with more severe forms of asthma might need additional treatments like daily corticosteroids, long-acting beta-adrenoceptor agonists, or leukotriene antagonists. In very severe cases, intravenous corticosteroids, magnesium sulfate, and oxygen therapy might be needed.
首先，患有哮喘的人应避免或尽量减少接触刺激物质，通过吸尘、清除地毯，改变环境条件，例如在霉菌多的潮湿地区烘干房间。还有一些药物可以减轻哮喘的症状，支气管扩张剂，如短效的β肾上腺素受体激动剂和抗胆碱能药物通常是通过紧急吸入器进行的。这些快速起作用的药物可以使肺部平滑肌放松，从而使气道扩张，帮助呼吸。较严重哮喘的个体可能需要额外的治疗，如日常的皮质类固醇、长效的β肾上腺素受体激动剂或白三烯拮抗剂。在非常严重的情况下，可能需要静脉注射糖皮质激素、硫酸镁和氧疗。
Alright, as a quick recap, asthma is characterized by chronic inflammation in the lungs as well as asthma exacerbations or attacks, where certain triggers starting up more inflammation which leads to smooth muscle spasms and mucus production, both of which make it hard to breathe.
快速回顾，哮喘的特点是肺部慢性炎症以及哮喘急性发作，某些因素会引发更多的炎症，导致平滑肌痉挛和粘液产生，这两者会导致呼吸困难。
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