Data Sheet 1_Infiltrating lipid-rich macrophage subpopulations identified as a regulator of increasing prostate size in human benign prostatic hyperplasia.xlsx

IntroductionMacrophages exhibit marked phenotypic heterogeneity within and across disease states, with lipid metabolic reprogramming contributing to macrophage activation and heterogeneity. Chronic inflammation has been observed in human benign prostatic hyperplasia (BPH) tissues, however macrophage activation states and their contributions to this hyperplastic disease have not been defined. We postulated that a shift in macrophage phenotypes with increasing prostate size could involve metabolic alterations resulting in prostatic epithelial or stromal hyperplasia.
MethodsSingle-cell RNA-seq of CD45+ transition zone leukocytes from 10 large (>90 grams) and 10 small (<40 grams) human prostates was conducted. Macrophage subpopulations were defined using marker genes and evaluated by flow cytometry.
ResultsBPH macrophages do not distinctly categorize into M1 and M2 phenotypes. Instead, macrophages with neither polarization signature preferentially accumulate in large versus small prostates. Specifically, macrophage subpopulations with altered lipid metabolism pathways, demarcated by TREM2 and MARCO expression, accumulate with increased prostate volume. TREM2high and MARCOhigh macrophage abundance positively correlates with patient body mass index and urinary symptom scores. TREM2high macrophages have a statistically significant increase in neutral lipid compared to TREM2low macrophages from BPH tissues. Lipid-rich macrophages were observed to localize within the stroma in BPH tissues. In vitro studies indicate that lipid-loaded macrophages increase prostate epithelial and stromal cell proliferation compared to control macrophages.
DiscussionThese data define two new BPH immune subpopulations, TREM2high and MARCOhigh macrophages, and suggest that lipid-rich macrophages may exacerbate lower urinary tract symptoms in patients with large prostates. Further investigation is needed to evaluate the therapeutic benefit of targeting these cells in BPH.

引言
巨噬细胞在疾病状态内部及跨疾病状态间表现出显著的表型异质性，脂质代谢重编程参与调控巨噬细胞的活化与表型异质性。人类良性前列腺增生（benign prostatic hyperplasia, BPH）组织中已被观测到存在慢性炎症，但巨噬细胞的活化状态及其在该增生性疾病中的作用尚未明确。本研究推测，随前列腺体积增大而发生的巨噬细胞表型转变，可能涉及代谢改变，进而促进前列腺上皮或基质增生。

方法
本研究对10例前列腺体积＞90g、10例＜40g的人类前列腺样本的CD45阳性移行带白细胞开展了单细胞RNA测序（single-cell RNA-seq）。借助标记基因定义巨噬细胞亚群，并通过流式细胞术（flow cytometry）进行验证。

结果
BPH相关巨噬细胞并未明确划分为M1与M2表型。反之，无任何极化特征的巨噬细胞亚群在前列腺体积较大的样本中优先富集。具体而言，以髓系细胞触发受体2（TREM2）和巨噬细胞清道夫受体MARCO的表达为特征、脂质代谢通路发生改变的巨噬细胞亚群，随前列腺体积增大而优先富集。TREM2高表达与MARCO高表达的巨噬细胞丰度与患者体质量指数及尿路症状评分呈正相关。与BPH组织中的TREM2低表达巨噬细胞相比，TREM2高表达巨噬细胞的中性脂质含量存在统计学意义上的显著升高。在BPH组织中，脂质富集的巨噬细胞定位于基质区域。体外实验表明，与对照巨噬细胞相比，脂质负载的巨噬细胞可促进前列腺上皮及基质细胞的增殖。

讨论
本研究明确了两种全新的BPH免疫细胞亚群：TREM2高表达与MARCO高表达巨噬细胞，并提示脂质富集的巨噬细胞可能加重前列腺体积较大患者的下尿路症状。未来仍需开展进一步研究，以评估靶向此类细胞用于BPH治疗的临床获益。