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壓力會加速免疫系統的老化

壓力會加速免疫系統的老化

老年婦女臉的概念

新的研究表明,壓力會加速免疫系統的老化,並有助於解釋與年齡相關的健康差異。

創傷性生活事件和日常壓力過早地削弱了身體的免疫細胞組合。

人們普遍認識到,當人們在過去幾年開始崛起時,他們的免疫系統就會減弱,一個明顯的例子就是持續的 COVID-19 大流行,老年人面臨的死亡率遠高於年輕人。

這種由正常衰老引起的免疫系統逐漸退化的過程稱為免疫缺陷。 但是,您可能認識年紀很大但很健康的人,反之亦然,即相對年輕但仍然容易感染的人。 什麼可以解釋同齡人免疫系統強度的差異?

壓力——以創傷事件、工作壓力、日常壓力和歧視的形式——加速了免疫系統的老化,這會增加一個人患癌症、心血管疾病和由諸如此類引起的感染的風險[{” attribute=””>COVID-19, according to a new University of Southern California (Founded in 1880, the University of Southern California is one of the world's leading private research universities. It is located in the heart of Los Angeles.

” data-gt-translate-attributes=”[{” attribute=””>USC) study.

The research, published yesterday (June 13, 2022) in the Proceedings of the National Academy of Sciences, could help explain disparities in age-related health, including the unequal toll of the pandemic, and identify possible points for intervention.

“As the world’s population of older adults increases, understanding disparities in age-related health is essential. Age-related changes in the immune system play a critical role in declining health,” said lead study author Eric Klopack, a postdoctoral scholar in the USC Leonard Davis School of Gerontology. “This study helps clarify mechanisms involved in accelerated immune aging.”

As people age, the immune system naturally begins a dramatic downgrade, a condition called immunosenescence. With advanced age, a person’s immune profile weakens, and includes too many worn-out white blood cells circulating and too few fresh, “naive” white blood cells ready to take on new invaders.

Potential problems relating to stress and the immune system

Immune aging is associated not only with cancer, but with cardiovascular disease, increased risk of pneumonia, reduced efficacy of vaccines, and organ system aging.

But what accounts for drastic health differences in same-age adults? USC researchers decided to see if they could tease out a connection between lifetime exposure to stress — a known contributor to poor health — and declining vigor in the immune system.

“Age-related changes in the immune system play a critical role in declining health.” — Eric Klopack

They queried and cross-referenced enormous data sets from University of Michigan’s Health and Retirement Study, a national longitudinal study of the economic, health, marital, family status, and public and private support systems of older Americans.

To measure exposure to various types of social stress, the researchers analyzed responses from a national sample of 5,744 adults over the age of 50. They answered a questionnaire designed to assess respondents’ experiences with social stress, including stressful life events, chronic stress, everyday discrimination and lifetime discrimination.

Blood samples from the participants were then analyzed through flow cytometry, a lab technique that counts and classifies blood cells as they pass one-by-one in a narrow stream in front of a laser.

As expected, people with higher stress scores had older-seeming immune profiles, with lower percentages of fresh disease fighters and higher percentages of worn-out white blood cells. The association between stressful life events and fewer ready-to-respond, or naive, T cells remained strong even after controlling for education, smoking, drinking, BMI, and race or ethnicity.

Some sources of stress may be impossible to control, but the researchers say there may be a workaround.

T-cells — a critical component of immunity — mature in a gland called the thymus, which sits just in front of and above the heart. As people age, the tissue in their thymus shrinks and is replaced by fatty tissue, resulting in reduced production of immune cells. Past research suggests that this process is accelerated by lifestyle factors like poor diet and low exercise, which are both associated with social stress.

“In this study, after statistically controlling for poor diet and low exercise, the connection between stress and accelerated immune aging wasn’t as strong,” said Klopack. “What this means is people who experience more stress tend to have poorer diet and exercise habits, partly explaining why they have more accelerated immune aging.”

Stress and the immune system: Impact of diet and exercise

Improving diet and exercise behaviors in older adults may help offset the immune aging associated with stress.

Additionally, cytomegalovirus (CMV) may be a target for intervention. CMV is a common, usually asymptomatic virus in humans and is known to have a strong effect on accelerating immune aging. Like shingles or cold sores, CMV is dormant most of the time but can flare up, especially when a person is experiencing high stress.

In this study, statistically controlling for CMV positivity also reduced the connection between stress and accelerated immune aging. Therefore, widespread CMV vaccination could be a relatively simple and potentially powerful intervention that could reduce the immune aging effects of stress, the researchers said.

Reference: “Social stressors associated with age-related T lymphocyte percentages in older US adults: Evidence from the US Health and Retirement Study” by Eric T. Klopack, Eileen M. Crimmins, Steve W. Cole, Teresa E. Seeman and Judith E. Carroll, 13 June 2022, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2202780119

In addition to Klopack, other authors include Eileen Crimmins, a University Professor and the AARP Chair in Gerontology at the USC Leonard Davis School; and Steve Cole and Teresa Seeman of UCLA.

The study was supported by grants from the National Institute on Aging (P30AG017265, U01AG009740).

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