Abstract

Recent studies have predominantly focused on the role of B cells in metabolic diseases, yet the function of B cells in adipose homeostasis remains unclear. Pax transactivation domain-interacting protein (PTIP), a licensing factor for humoral immunity, is necessary for B cell development and activation. Here, using mice that lack PTIP in B cells (PTIP^−/− mice), we explored the role of B cells in adipose homeostasis under physiological conditions. Fat deposition in 8-week-old mice was measured by micro-CT, and PTIP^−/− mice presented a marked decrease in the deposition of subcutaneous adipose tissue (SAT). Untargeted lipidomics revealed that the triglyceride composition in SAT was altered in PTIP^−/− mice. In addition, there was no difference in the number of adipocyte progenitor cells in the SAT of wild-type (WT) and PTIP^−/− mice as measured by flow cytometry. To study the effects of steady-state IgM and IgG antibody levels on fat deposition, PTIP^−/− mice were injected intraperitoneally with serum from WT mice once every 3-4 days for 4 weeks. The iSAT mass of the recipient mice showed no significant increase in comparison to the controls after 4 weeks of injections. Our findings reveal that PTIP plays an essential role in regulating subcutaneous adipocyte size, triglyceride composition, and fat deposition under physiological conditions by controlling B cells. The decreased subcutaneous fat deposition in PTIP^−/− mice does not appear to be related to the number of adipocyte progenitor cells. The steady-state levels of IgM and IgG antibodies in vivo are not associated with the subcutaneous fat deposition.

中文翻译：

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B淋巴细胞中的PTIP缺乏症减少了小鼠的皮下脂肪沉积

摘要

最近的研究主要集中在B细胞在代谢性疾病中的作用，但B细胞在脂肪稳态中的功能仍不清楚。Pax反式激活域相互作用蛋白（PTIP）是体液免疫的许可因素，对于B细胞的发育和激活是必需的。在这里，我们使用在B细胞中缺乏PTIP的小鼠（PTIP ^-/-小鼠），探索了生理条件下B细胞在脂肪稳态中的作用。通过微型CT测量了8周龄小鼠中的脂肪沉积，并且PTIP ^-/-小鼠皮下脂肪组织（SAT）的沉积显着减少。非靶向脂质组学显示SAT中的甘油三酸酯成分在PTIP中发生了改变^-/-老鼠。另外，通过流式细胞术测量，野生型（WT）和PTIP ^-/-小鼠的SAT中脂肪细胞祖细胞的数量没有差异。为了研究稳态IgM和IgG抗体水平对脂肪沉积的影响，对PTIP ^-/-小鼠腹腔注射WT小鼠血清，每3-4天一次，共4周。注射4周后，与对照组相比，受体小鼠的iSAT质量没有显示出明显的增加。我们的发现表明PTIP在生理条件下通过控制B细胞在调节皮下脂肪细胞大小，甘油三酸酯成分和脂肪沉积中起着至关重要的作用。PTIP中皮下脂肪沉积减少^-/-小鼠似乎与脂肪细胞祖细胞的数量无关。体内IgM和IgG抗体的稳态水平与皮下脂肪沉积无关。