IL-10 signaling remodels adipose chromatin architecture to limit thermogenesis and energy expenditure [ATAC-Seq]

Signaling pathways that promote adipose tissue thermogenesis are well characterized, but the physiologic limiters of energy expenditure are largely unknown. Here we show that ablation of the anti-inflammatory cytokine IL-10 improves insulin sensitivity, protects against diet-induced obesity, and elicits the browning of white adipose tissue. Mechanistic studies define bone marrow cells as the source of the IL-10 signal and mature adipocytes as the target cell type mediating these effects. IL-10 receptor alpha is highly enriched in mature adipocytes and is induced in response to cold, obesity and aging. ATAC-seq and RNA-seq reveal that IL-10 represses the transcription of thermogenic genes in adipocytes by altering chromatin accessibility and inhibiting ATF and PGC-1alpha recruitment to key enhancer regions. These findings identify the IL-10 axis as a critical and potentially targetable regulator of thermogenesis, and expand our understanding of the links between inflammatory signaling and adipose tissue function in the setting of obesity. Immortalized brown/beige-like preadipocyte cell line (iBAd Cells) was used for ATAC-Seq and mRNA-Seq. For RNA-Seq, triplicate experiments were performed, for ATAC-Seq individual samples were sequenced after 5 days of differentiation with either control treatment, or including IL-10 overnight prior to addition of Isoproterenol for 5-6 hours. Inguinal White adipose tissue was used for RNA-Seq from either WT or IL-10-/- animals, where 11 IL10-/- mice and 9 WT mice were seperately pooled for library construction and sequencing. Primary SVF on day 9 of differentiation or primary adipose was used for ATAC-Seq. ATAC-Seq individual samples were sequenced with either control treatment, or including IL-10 overnight prior to addition of FSK. Inguinal White adipose tissue from 10 weeks old chow-fed mice were used for isolation of primary adipose nuclei.

促进脂肪组织产热的信号通路已得到充分表征，但能量消耗的生理限制因子仍未明确。本研究发现，抗炎细胞因子白细胞介素-10（IL-10）的基因敲除可提升胰岛素敏感性、抵抗饮食诱导型肥胖，并诱导白色脂肪组织褐变。机制研究明确了骨髓细胞为IL-10信号的来源，而成熟脂肪细胞为介导上述效应的靶细胞类型。IL-10受体α（IL-10 receptor alpha）在成熟脂肪细胞中高度富集，并可在寒冷、肥胖及衰老刺激下被诱导表达。转录组测序（RNA-seq）与转座酶可及性测序（ATAC-seq）结果显示，IL-10可通过改变染色质可及性、抑制转录因子ATF及过氧化物酶体增殖物激活受体γ辅激活因子1α（PGC-1α）向关键增强子区域的募集，从而抑制脂肪细胞中产热基因的转录。本研究结果证实IL-10信号轴是产热过程的关键且可靶向调控的调节因子，并加深了我们对肥胖状态下炎症信号通路与脂肪组织功能之间关联的认知。本研究使用永生化棕色/米色样前脂肪细胞系（iBAd Cells）进行ATAC-seq与mRNA-seq实验：mRNA-seq实验设置三次生物学重复；ATAC-seq则对经过5天分化后的样本进行测序，这些样本分别接受对照处理，或在加入异丙肾上腺素（Isoproterenol）处理5-6小时前，先用IL-10孵育过夜。取野生型（WT）与IL-10基因敲除（IL-10-/-）小鼠的腹股沟白色脂肪组织进行mRNA-seq，其中11只IL10-/-小鼠与9只WT小鼠分别混合后构建文库并测序。分化第9天的原代基质血管成分（stromal vascular fraction, SVF）或原代脂肪组织被用于ATAC-seq实验：ATAC-seq的单一样本分别接受对照处理，或在加入福司柯林（FSK）处理前先用IL-10孵育过夜。取10周龄普通饲料喂养小鼠的腹股沟白色脂肪组织，用于分离原代脂肪细胞核。