Updated | A new study has shed light on the role our immune system could play in our hair turning gray when we deal with stress or illness.
更新|一項新的研究揭示了當我們在應對壓力或疾病時，我們的免疫系統在我們的頭髮變得灰白時所扮演的角色。
Cells known as melanocytes make up melanin and give our hair its color. Special stem cells then add melanocytes to new follicles when our hair falls out. When these stem cells stop working, our hair loses its pigment. It is this process and its relationship with our immune system's defenses that scientists at the National Institutes of Health (NIH) and the University of Alabama, Birmingham, (UAB) set out to investigate—in mice.
被稱為黑色素細胞的細胞組成了黑色素，並賦予頭髮顏色。當我們的頭髮脫落時，特殊的幹細胞會將黑色素細胞添加到新的毛囊中。當這些幹細胞停止工作時，我們的頭髮就失去了色素。美國國立衛生研究院（NIH）和阿拉巴馬大學伯明翰分校（UAB）的科學家開始在老鼠身上進行研究，這一過程及其與免疫系統的防禦的關係。
Our immune system is constantly defending us against viruses and bacteria, prompting cells under attack to produce signaling molecules called interferons. Interferons tell other cells to turn on the gene expression that prevents viruses from replicating, and trigger immune effector cells that protect the body.
我們的免疫系統不斷地保護我們免受病毒和細菌的侵害，促使被攻擊的細胞產生稱為干擾素的信號分子。干擾素告訴其他細胞打開阻止病毒複製的基因表達，並觸發免疫效應細胞保護身體。
Scientists believe the immune system could play a part in our hair turning gray.
科學家們認為，免疫系統可以在我們的頭髮變成灰白色時發揮作用。
JD MASON/UNSPLASH
For their paper, published in the journal PLOS Biology, the authors studied how the immune system’s response to attacks affects the MITF protein, which helps melanocytes to function. They found that when MITF loses control of the interferon response in melanocyte stem cells, the hair can turn gray. What's more, mice genetically predisposed to developing gray hair had this response even when the immune response was turned on artificially. Further research is now needed to understand what caused these reactions and also to see if these effects occur in the human body too.
他們的論文發表在PLOS Biology雜誌上，研究人員研究了免疫系統對攻擊的反應如何影響MITF蛋白質，從而幫助黑素細胞發揮作用。他們發現，當MITF失去對黑素細胞幹細胞中干擾素反應的控制時，頭髮會變成灰色。更重要的是，即使當免疫反應被人為地打開時，遺傳傾向於發育成白髮的老鼠也有這種反應。現在需要進一步的研究來了解造成這些反應的原因，以及這些反應是否也發生在人體中。
The scientists hope their research will offer new insights into diseases that affect pigmentation, including vitiligo, a condition that destroys pigment cells in the skin.
科學家們希望他們的研究能夠為影響色素沉著的疾病提供新的見解，包括白癜風，這是一種破壞皮膚色素細胞的疾病。
Melissa Harris, lead author of the study and an assistant professor in UAB's Biology Department, said in a statement, "Genomic tools allow us to assess how all of the genes within our genome change their expression under different conditions, and sometimes they change in ways that we don't anticipate.”
"We are interested in genes that affect how our stem cells are maintained over time. We like to study gray hair because it's an easy read-out of melanocyte stem celldysfunction," Harris added.
“我們對影響我們幹細胞長期維持的基因很感興趣。我們喜歡研究灰色頭髮因為它很容易就能讀出黑色素細胞的幹細胞功能障礙，”Harris補充說。
William Pavan, chief of the Genetic Disease Research Branch at the NIH's National Human Genome Research Institute and co-author of the study, said in a statement, "This new discovery suggests that genes that control pigment in hair and skin also work to control the innate immune system.
"These results may enhance our understanding of hair graying. More importantly, discovering this connection will help us understand pigmentation diseases with innate immune system involvement like vitiligo," he said.
“這些結果可能會加深我們對頭髮變白的理解，更重要的是，發現這種聯繫將有助於我們理解像白癜風一樣與先天性免疫系統有關的色素疾病，”他說。
The research follows a 2016 study by academics at University College London (UCL) that, for the first time, linked the gene called IRF4 to going gray.
這項研究是由倫敦大學學院（UCL）的學者在2016年進行的一項研究得出的，該研究首次將稱為IRF4的基因與變灰關聯起來。
The lead author, Kaustubh Adhikari of UCL's Cell and Developmental Biology Department, said in a statement at the time, “We already know several genes involved in balding and hair color, but this is the first time a gene for graying has been identified in humans, as well as other genes influencing hair shape and density.”
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