Study offers insight on how hot weather impairs the immune system

一项研究观察了免疫系统对炎热天气的反应，为了解气温上升时发生的情况提供了新的见解.

研究人员发现，炎热的天气与人体免疫反应之间存在联系, including levels of certain blood cells and indicators of inflammation. 这是朝着最终找到有助于保护人们免受危险高温伤害的治疗方法迈出的一步, which have been linked to increased rates of heart attack, stroke and other cardiovascular issues.

的 研究, presented Tuesday at the 美国心脏协会's Epidemiology, 预防, Lifestyle and Cardiometabolic Health conference in Chicago, 在完整的结果发表在同行评议的期刊上之前被认为是初步的.

之前的研究已经将温度和炎症联系起来，首席研究员Dr. 丹尼尔·W. 里格斯, 他是肯塔基州路易斯维尔大学医学院环境医学系的流行病学家和助理教授.

炎症, which is associated with heart disease risk, is part of the body's response to infection or injury. Different types of white blood cells also are part of that immune response. 其中一些细胞释放一种叫做细胞因子的蛋白质，这种蛋白质可以调节炎症. Other immune cells attack invaders such as bacteria and viruses directly.

细胞因子和免疫细胞可以作为身体对感知到的威胁作出反应时加强防御的标志来衡量.

早期关于热和炎症的研究只关注了身体如何反应的几个信号, 里格斯说. 他和他的同事们“想要更全面地了解高温和这些标志物之间的关系."

的 team looked at blood samples taken from 624 people who were part of the 绿心计划, 他们正在研究在路易斯维尔社区种植绿色植物如何改善空气质量并减少心脏病.

Study participants ranged in 年龄 from 20 to 70 years, with an aver年龄 年龄 of 50. About 77% were white, 18% were Black, and 59% were women. Each person gave one blood sample during the summers of 2018 and 2019.

研究人员在每个样本中测量了11种细胞因子和9种免疫细胞. 使用通用热气候指数评估每次抽血当天的天气, a measure of how temperature, humidity and wind speed affect the human body's comfort level. 的 aver年龄 24-hour UTCI during the measurements was 78 degrees Fahrenheit.

的 blood measurement was then matched with the weather readings, and the results were adjusted for differences in demographic factors such as sex, 年龄, 种族与教育. 的 results also were adjusted for body mass index (a measure of obesity), 空气污染和患者是否吸烟或服用消炎药.

研究结果表明，炎热的天气与几种细胞因子水平的升高有关. 其中之一, tnf, 是“主要炎症标志物之一，在心血管疾病中起重要作用?,里格斯说.

同时, 炎热的天气与被称为单核细胞的某些类型的白细胞水平升高有关, 这可能是高温引起炎症或引发免疫反应的迹象吗, 里格斯说.

Heat also was associated with reduced levels of another class of monocyte, 被称为非经典, 这会降低炎症. 高温还与抗感染和清洁血液的白细胞(B细胞)水平降低有关. 里格斯说，这些细胞的水平较低可能意味着一个人更容易受到感染.

他惊讶地发现，短期暴露在炎热天气下，如此多类型的细胞会发生变化. 的 study did not look at what could be causing that, 但里格斯说，热适应可能会导致热休克蛋白的增加, which are known to be involved in immune and inflammatory responses.

"I think this is an important study," said Dr. 朱迪斯·里奇曼, 纽黑文耶鲁大学公共卫生学院慢性疾病流行病学系主任, 康涅狄格. 她曾做过温度如何影响中风率的研究，但没有参与这项新研究.

之前的许多研究都着眼于热浪是否会导致更多的住院治疗或死亡, 她说. "What's so valuable about this study is they're really trying to understand, 在身体层面, the mechanisms that may be contributing to this increased risk."

的 study looks only at one neighborhood, 她说, so the findings need to be replicated more broadly. 在这样的研究中, it's not clear how much people are actually being exposed to the outdoor heat; people could be staying inside in air conditioning.

But overall, Lichtman said, this study is "opening up a new area of 研究.“随着气候的变化，了解热量对身体的影响将变得越来越重要, 如果研究人员能够开始了解环境的各个方面是如何影响健康的, "maybe we can also come up with novel ways to reduce our cardiovascular risk."

里格斯说，气候变化预计会增加极端高温沙巴体育平台点击进入的数量. “我们未来的研究将集中在极端高温沙巴体育平台点击进入对免疫反应和炎症的长期影响上, and how this relates to the progression of cardiovascular disease."

As part of the 绿心计划 in Louisville, 里格斯说, “我们将研究植树是否真的可以减轻对免疫系统和炎症的影响." Other ongoing 研究 involves collecting additional blood samples. "的 major limitation of this study is that it's only one time point,他说, and additional samples will show whether the findings persist.

"的 more you understand the mechanism, the more you can clearly work on prevention and treatment,他说.