Department of Orthopedic Surgery, Kitasato University School of Medicine, 1-15-1 Minami-ku Kitasato, Sagamihara City, Kanagawa 252-0374, Japan.
Shonan University of Medical Sciences Research Institute, Nishikubo 500, Chigasaki City, Kanagawa 253-0083, Japan.
Biomed Res Int. 2021 Jul 12;2021:7988320. doi: 10.1155/2021/7988320. eCollection 2021.
Age is a key factor in intervertebral disc (IVD) degeneration; however, the changes that occur in IVDs with age are not fully understood. Tissue-resident macrophages are critical for tissue homeostasis and are regulated by transforming growth factor- (TGF-) . We examined changes in the proportion of resident macrophages in young versus aged mice and the role of TGF- in regulating resident macrophages in IVDs. IVDs were harvested from 4-month (young) and 18-month-old (aged) C57BL/6J mice. The proportion of macrophages in IVDs was determined using flow cytometry ( = 5 for each time point) and the expression of , , and genes, which encode CD11b, CD206, and TGF- protein, respectively, using real-time PCR. To study the role of TGF- in the polarization of resident macrophages, resident macrophages isolated from IVDs from young and aged mice were treated with recombinant TGF- with and without a TGF- inhibitor (SB431542). Additionally, SB431542 was intraperitoneally injected into young and aged mice, and expression was examined using real-time PCR ( = 10 for each time point). The proportion of CD11b+ and CD11b+ CD206+ cells was significantly reduced in aged versus young mice, as was , , and expression. TGF-/IL10 stimulation significantly increased the expression of , an M2 macrophage marker, in disc macrophages from both young and aged mice. Meanwhile, administration of a TGF- inhibitor significantly reduced expression compared to vehicle control in both groups. . Resident macrophages decrease with age in IVDs, which may be associated with the concomitant decrease in TGF-. Our findings provide new insight into the mechanisms of age-related IVD pathology.
年龄是椎间盘（IVD）退变的一个关键因素；然而，随着年龄的增长，IVD 发生的变化尚不完全清楚。组织驻留巨噬细胞对于组织稳态至关重要，并受转化生长因子（TGF-）调节。我们研究了年轻和老年小鼠的 IVD 中驻留巨噬细胞的比例变化，以及 TGF-在调节 IVD 中驻留巨噬细胞中的作用。从小鼠的 4 月龄（年轻）和 18 月龄（年老）收集 IVD。使用流式细胞术（每个时间点 = 5）确定 IVD 中的巨噬细胞比例，并使用实时 PCR 检测编码 CD11b、CD206 和 TGF-蛋白的 、 和 基因的表达。为了研究 TGF-在驻留巨噬细胞极化中的作用，从小鼠的年轻和老年 IVD 中分离出驻留巨噬细胞，并用重组 TGF-处理，同时用 TGF-抑制剂（SB431542）处理。此外，将 SB431542 腹腔内注射到年轻和老年小鼠中，并使用实时 PCR 检测 表达（每个时间点 = 10）。与年轻小鼠相比，年老小鼠的 CD11b+和 CD11b+ CD206+细胞比例显著降低， 、 、 和 表达也降低。TGF-/IL10 刺激显著增加了来自年轻和老年小鼠椎间盘巨噬细胞中 M2 巨噬细胞标志物 的表达。同时，与载体对照相比，TGF-抑制剂的给药显著降低了两组的 表达。总之，IVD 中的驻留巨噬细胞随年龄的增长而减少，这可能与 TGF-的同时减少有关。我们的研究结果为年龄相关性 IVD 病理学的机制提供了新的见解。
