Liver sinusoidal endothelial cells (LSECs) and Kupffer cells (KCs; liver resident macrophages) form the body’s most effective scavenger cell system for the removal of harmful blood-borne substances, ranging from modified self-proteins to pathogens and xenobiotics. Controversies in the literature regarding the LSEC phenotype pose a challenge when determining distinct functionalities of KCs and LSECs. This may be due to overlapping functions of the two cells, insufficient purification and/or identification of the cells, rapid dedifferentiation of LSECs in vitro, or species differences. We therefore characterized and quantitatively compared expressed gene products of freshly isolated, highly pure LSECs (fenestrated SE-1/FcγRIIb2+) and KCs (CD11b/c+) from Sprague Dawley, Crl:CD (SD), male rats using high throughput mRNA-sequencing and label-free proteomics. We observed a robust correlation between the proteomes and transcriptomes of the two cell types. Integrative analysis of the global molecular profile demonstrated the immunological aspects of LSECs. The constitutive expression of several immune genes and corresponding proteins of LSECs bore some resemblance with the expression in macrophages. LSECs and KCs both expressed high levels of scavenger receptors (SR) and C-type lectins. Equivalent expression of SR-A1 (Msr1), mannose receptor (Mrc1), SR-B1 (Scarb1), and SR-B3 (Scarb2) suggested functional similarity between the two cell types, while functional distinction between the cells was evidenced by LSEC-specific expression of the SRs stabilin-1 (Stab1) and stabilin-2 (Stab2), and the C-type lectins LSECtin (Clec4g) and DC-SIGNR (Clec4m). Many immune regulatory factors were differentially expressed in LSECs and KCs, with one cell predominantly expressing a specific cytokine/chemokine and the other cell the cognate receptor, illustrating the complex cytokine milieu of the sinusoids. Both cells expressed genes and proteins involved in antigen processing and presentation, and lymphocyte co-stimulation. Our findings support complementary and partly overlapping scavenging and immune functions of LSECs and KCs. This highlights the importance of including LSECs in studies of liver immunity, and liver clearance and toxicity of large molecule drugs and nano-formulations.

中文翻译：

---

转录组和蛋白质组图谱揭示了大鼠肝正弦内皮细胞和肝巨噬细胞的互补清除剂和免疫特征

肝窦形内皮细胞（LSEC）和库普弗细胞（KC;肝脏常驻巨噬细胞）形成了人体最有效的清除细胞系统，用于清除有害的血源性物质，从修饰的自身蛋白到病原体和异种生物。当确定KC和LSEC的不同功能时，有关LSEC表型的文献争议提出了挑战。这可能是由于两个细胞的功能重叠，细胞的纯化和/或鉴定不足，体外LSEC的快速去分化或物种差异所致。因此，我们对来自Sprague Dawley，Crl：CD（SD）的新鲜分离的高纯度LSEC（有孔SE-1 /FcγRIIb2+）和KC（CD11b / c +）的表达基因产物进行了表征和定量比较，使用高通量mRNA测序和无标记蛋白质组学的雄性大鼠。我们观察到两种细胞类型的蛋白质组和转录组之间的密切相关。整体分子概况的综合分析表明LSECs的免疫学方面。LSEC的几种免疫基因和相应蛋白的组成型表达与巨噬细胞中的表达有些相似。LSEC和KC均表达高水平的清道夫受体（SR）和C型凝集素。SR-A1（Msr1），甘露糖受体（Mrc1），SR-B1（Scarb1）和SR-B3（Scarb2）的等效表达表明两种细胞类型之间的功能相似，而细胞之间的功能差异则由LSEC- SRs stabilin-1（Stab1）和stabilin-2（Stab2）的特定表达，C型凝集素LSECtin（Clec4g）和DC-SIGNR（Clec4m）。许多免疫调节因子在LSEC和KC中差异表达，一个细胞主要表达特定的细胞因子/趋化因子，另一个细胞表达同源的受体，说明了正弦曲线的复杂细胞因子环境。两种细胞均表达参与抗原加工和呈递以及淋巴细胞共刺激的基因和蛋白质。我们的发现支持LSEC和KC的互补和部分重叠的清除和免疫功能。这凸显了将LSECs纳入肝免疫研究，大分子药物和纳米制剂的肝清除率和毒性研究的重要性。其中一个细胞主要表达特定的细胞因子/趋化因子，另一个细胞表达同源受体，说明了正弦曲线的复杂细胞因子环境。两种细胞均表达参与抗原加工和呈递以及淋巴细胞共刺激的基因和蛋白质。我们的发现支持LSEC和KC的互补和部分重叠的清除和免疫功能。这凸显了将LSECs纳入肝免疫研究，大分子药物和纳米制剂的肝清除率和毒性研究的重要性。其中一个细胞主要表达特定的细胞因子/趋化因子，另一个细胞表达同源受体，说明了正弦曲线的复杂细胞因子环境。两种细胞均表达参与抗原加工和呈递以及淋巴细胞共刺激的基因和蛋白质。我们的发现支持LSEC和KC的互补和部分重叠的清除和免疫功能。这凸显了将LSECs纳入肝免疫研究，大分子药物和纳米制剂的肝清除率和毒性研究的重要性。我们的发现支持LSEC和KC的互补和部分重叠的清除和免疫功能。这凸显了将LSECs纳入肝免疫研究，大分子药物和纳米制剂的肝清除率和毒性研究的重要性。我们的发现支持LSEC和KC的互补和部分重叠的清除和免疫功能。这凸显了将LSECs纳入肝免疫研究，大分子药物和纳米制剂的肝清除率和毒性研究的重要性。