探討年齡對調節性B細胞的族群與功能差異的影響

Abstract

調節性 B 細胞 (Regulatory B cells, Bregs)是一類對免疫調節至關重要的B細胞，其定義主要依賴於它們產生的IL-10、IL-35和TGF-β等功能性分子，而不像Tregs一樣有明確的標誌分子（如Foxp3)。本研究探討了不同年齡組別小鼠脾臟和腹膜沖洗細胞以及Peyer’s patches中的Bregs族群，也對其功能性分子IL-10以及TGF-β的表現進行探討。我們將實驗分為成年組、中年組與老年組小鼠，並使用流式細胞儀分析Bregs族群，檢測脾臟中B10細胞（CD1dhiCD5+）、CD9+ B細胞、CD21hiCD23- MZ B細胞和Tim-1+ B細胞，這些Bregs族群在老化過程中呈現上升的趨勢。在腹膜沖洗細胞中，我們發現B1a細胞在中年組的比例也有增加的趨勢。這可能表示在老化過程中，腹腔中聚集了B1a細胞。而後我們分析了PP中的tolerogenic B cells (TolBC) 族群，結果顯示其比例在成年組和中年組之間保持相對一致，然而在老年組中卻顯著的上升，這些細胞的誘導Treg細胞的能力仍需要進一步研究。然後我們探討脾臟Bregs中IL-10+細胞的比例：我們發現在中年組脾臟B細胞中，IL-10+細胞的比例在脾臟Breg族群有上升的趨勢，這可能與免疫調節和老化過程有關，而將Breg純化出來進行功能性探討發現，B10、CD9+ B、B1a細胞分泌IL-10的能力在中年組相較於成年組有增加的情況，TGF-β的分泌則沒有顯著的差別，各Breg誘導T細胞死亡在年紀間沒有差別，誘導Treg分化的能力也在年紀組別間沒有顯著差別，然而，CD9+ B細胞、B1a細胞在中年組抑制T細胞增殖的能力顯著高於成年組，顯示老化可能使Breg的能力增加。整體而言，大部份Breg族群與IL-10在中年組中有增加的趨勢，並且抑制T細胞的功能也隨之上升，然而這背後的分子機制以及造成差異的原因仍有待進一步確認。

Regulatory B cells (Bregs) are a crucial subset of B cells involved in immune regulation, primarily defined by their production of functional molecules such as IL-10, IL-35, and TGF-β, unlike Tregs which have clear markers like Foxp3. This study investigated Breg populations in the spleen, peritoneal lavage cells, and Peyer's patches of mice from different age groups, focusing on the expression of functional molecules IL-10 and TGF-β. We divided the studying groups into young-adult, middle-aged, and old mice groups and used flow cytometry to analyze Breg populations. In the spleen, we examined B10 cells (CD1dhiCD5+), CD9+ B cells, CD21hiCD23- marginal zone (MZ) B cells, and Tim-1+ B cells, all of which showed an increasing trend with aging. In peritoneal cavity cells, we observed an increase in the proportion of B1a cells in the middle-aged and old group, indicating an accumulation of B1a cells in the peritoneum during aging. Next, we analyzed the tolerogenic B cells (TolBC) population in Peyer's patches. The results showed that its proportion remained relatively consistent between the adult and middle-aged groups but significantly increased in the old group. The ability of these cells to induce Treg cells still requires further investigation. We then examined the proportion of IL-10+ cells among splenic Bregs and found an increasing trend in the middle-aged group, which might be related to immune regulation and aging. Functional analysis of purified Bregs revealed that B10, CD9+ B, and B1a cells had an increased ability to secrete IL-10 in the middle-aged group compared to the young-adult group, while the secretion of TGF-β did not show significant differences. The ability of different Breg subsets to induce T cell death and Treg differentiation did not significantly vary with age. However, CD9+ B cells and B1a cells in the middle-aged group showed a significantly higher ability to inhibit T cell proliferation than those in the adult group, suggesting that aging might affect Breg function. Overall, most Breg populations and IL-10 production showed an increasing trend in the middle-aged group, along with an enhanced ability to inhibit T cell proliferation. However, the underlying molecular mechanisms and reasons for these changes still require further investigation.