Exploring the function of immune cells in the heart of high-altitude yaks based on transcriptomic sequencing data

doi:10.16829/j.slxb.151004

Abstract

Abstract:

Hypoxia can affect the redox state of animal tissue cells, leading to endoplasmic reticulum（ER）stress. The heart plays a crucial role in the regulation of oxygen supply and demand in the body and is particularly susceptible to damage under ER stress. Yaks, which live year-round in high-altitude hypoxic environments, have adapted well to these conditions. However, the changes in immune cell functions within the hearts of high-altitude yaks in response to hypoxia-induced endoplasmic reticulum (ER) stress are not yet fully understood. To address this, we selected yaks from two different altitudes in Qinghai Province, China: Qumalai County (4 500 m) and Xunhua County (2 600 m). We then used transcriptome and single-cell transcriptome sequencing to investigate differences in immune-related gene expression and functional changes in major immune cells in the hearts of yaks from high and low altitudes. This study aims to deepen our understanding of the adaptive changes in the immune characteristics of yak heart tissues. The results from transcriptome sequencing data showed that, compared to low-altitude yaks, upregulated genes in the hearts of high-altitude yaks were primarily enriched in pathways related to ER stress, damaged cell clearance, and the removal of misfolded proteins, all of which are associated with immune function. Gene Set Enrichment Analysis (GSEA) revealed that pathways related to ER stress, damaged cell clearance, and the removal of misfolded proteins were activated in the heart tissues of high-altitude yaks. RT-qPCR experiments confirmed that the expression levels of immune-related genes (eg.LCP1, HLA-A, IGHM, FCGR3) were significantly higher in the heart tissues of high-altitude yaks compared to those of low-altitude yaks (P < 0.05), and the expression trends were consistent with the transcriptome results. Single-cell transcriptome sequencing results showed a decrease in the frequency of lymphocytes, macrophages, and dendritic cells in the heart tissues of high-altitude yaks. Furthermore, the sequencing revealed that upregulated genes in these three types of immune cells in high-altitude yaks were significantly enriched in immune pathways, including Fcγ-R-mediated phagocytosis, T-cell receptor signaling, and antigen processing and presentation, all of which are involved in the clearance of cellular foreign bodies. In summary, the enhanced phagocytic, cytotoxic, and immune complex clearance capabilities of immune cells in the hearts of high-altitude yaks effectively ensure the removal of increased misfolded proteins and other foreign bodies induced by ER stress. This adaptation helps them better cope with the high-altitude hypoxic environment.

Key words: Yak (Bos grunniens), Heart, Immune effects, Plateau environmental adaptation, Single-cell transcriptome

摘要：

低氧会影响动物组织细胞氧化还原状态导致内质网应激，心脏在机体氧供需平衡调控中至关重要，在内质网应激下容易受到损伤。终年生活在高海拔低氧环境的牦牛（Bos grunniens）对高原环境具有良好的适应，但高海拔牦牛心脏组织为应对低氧造成的内质网应激，其免疫细胞相关功能有何变化尚不清楚。为此，本研究选取青海曲麻莱县（海拔4 500 m）与循化县（海拔2 600 m）不同海拔的高原型牦牛作为研究对象，利用转录组测序和单细胞转录组测序技术来探究高、低海拔牦牛心脏组织中免疫作用相关基因表达差异和主要免疫细胞的功能变化，以期进一步了解牦牛心脏组织在免疫方面的适应性变化。转录组测序数据分析结果表明，相对于低海拔牦牛，高海拔牦牛心脏中上调表达基因主要富集在内质网应激导致的受损细胞、错误蛋白清除等与免疫功能相关的通路上；GSEA分析发现高海拔牦牛心脏组织中，与内质网应激、内质网应激导致的受损细胞、错误蛋白清除的通路均被激活；RT‑qPCR实验表明免疫相关基因（LCP1、HLA‑A、IGHM、FCGR3等）的表达量在高海拔牦牛心脏组织中显著高于低海拔牦牛（P < 0.05），且表达趋势与转录组结果一致；单细胞转录组测序结果显示，高海拔牦牛心脏组织中淋巴细胞、巨噬细胞和树突状细胞3种免疫细胞的细胞频率下降，且单细胞转录组测序发现高海拔牦牛3种免疫细胞中上调表达基因均显著富集在Fcγ‑R介导的吞噬通路、T细胞受体信号、抗原处理和呈递通路等细胞异物清除的免疫通路中。综上，高海拔牦牛心脏免疫细胞吞噬、杀伤、免疫复合物清除等能力的增强，可有效保证内质网应激引起的细胞内错误折叠蛋白等异物增加的清除功能，以更好地适应高原低氧环境。

关键词: 牦牛, 心脏, 免疫作用, 高原环境适应, 单细胞转录组

CLC Number:

Q952

Xun ZHANG, Nating HUANG, Jingyi LI, Jiarui CHEN, Qing WEI. Exploring the function of immune cells in the heart of high-altitude yaks based on transcriptomic sequencing data[J]. ACTA THERIOLOGICA SINICA, 2026, 46(2): 171-183.

张迅, 黄娜婷, 李静怡, 陈家瑞, 魏青. 基于转录组测序数据探讨高海拔牦牛心脏免疫细胞的功能[J]. 兽类学报, 2026, 46(2): 171-183.

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URL: https://www.mammal.cn/EN/10.16829/j.slxb.151004

https://www.mammal.cn/EN/Y2026/V46/I2/171

Figures/Tables 9

Table 1 RT-qPCR primer information

基因 Gene	引物序列（5′-3′） Primer sequence（5′-3′）	片段长度 Product length/bp
GAPDH	F： CATCACTGCCACCCAGAAGAC R： AGTGAGTGTCGCTGTTGAAGTCG	335
LCP1	F： TTTGGCTGCCAGAACTGTTGC R： GCAGCTGATGTACCCATTGC	129
HLA-A	F： CAGGCTGTAGGCTACGTGGATG R： GGCCATCTTCCTGGATCTCAC	247
IGHM	F： TCGCCGACATCTTCCTCACA R： TCGCTCAAAATACGTGTGGGTC	134
FCGR3	F： AATGGTGGCACAATGGGACT R： CTGGACCTTTGCTACAGGAGTTT	245

Fig. 1 Volcano map of differentially expressed genes in high and low altitude yak heart tissue

Fig. 2 Relative expression of mRNAs of immunity-related genes in yaks at high and low altitudes. * indicates significant difference, P < 0.05; ** indicates highly significant difference, P < 0.01

Fig. 3 Map of GO (A) and KEGG (B) enrichment analysis of up-regulated genes expressed in high and low altitude yak heart tissues. The vertical coordinate is -log10 (Qvalue), the horizontal coordinate is the Z-score value (the difference between the number of up-regulated differential genes and the number of down-regulated differential genes as a proportion of the total number of differential genes), and the yellow line represents the threshold of Qvalue = 0.05

Table 2 Highly expressed immunity genes

基因 Gene	差异倍数 FC	P值 P value	功能描述 Description
CD3D	1.70	4.78E-19	TCR受体复合物 TCR receptor complex
CD8A	1.90	5.55E-10	CD8蛋白 CD8 protein
PRF1	2.67	1.70E-18	编码穿孔素蛋白，直接参与细胞杀伤 Encodes perforin protein， directly involved in cell killing
LCP1	1.81	4.75E-34	LCP1响应CD28蛋白的共刺激增强第二信号的传导 LCP1 enhances second signalling in response to co-stimulation of CD28 protein
HLA-A	1.50	6.24E-06	MHCI蛋白 MHCI protein
IGHM	1.68	5.87E-18	免疫球蛋白Fc区 Immunoglobulin Fc zone
FCGR3	2.78	2.70E-11	Fcγ 受体 Fcγ receptor
RAC2	1.79	3.88E-12	增强吞噬细胞吞噬作用 Enhancement of phagocytosis by phagocytes
IL2RB	1.40	9.00E-26	IL-2受体 IL-2 receptor

Fig. 4 Analysis of GO term (A) and KEGG Pathway GSEA (B) in high and low altitude yak heart tissue.QML: The yaks of Qumalai County; XH-Y: The yaks of Xunhua County

Fig. 5 Cell frequencies of cardiac tissue-associated immune cells in yaks at high and low altitude

Fig. 6 Enrichment analysis of KEGG, a gene differentially expressed by three immune cells in the heart of yaks at high and low altitudes. A: lymphocytes; B: macrophages; C: dendritic cells

Fig. 7 Pathway map of relevant immune genes. A: activation of CD8+T cells and clearance of endoplasmic reticulum stress damaged cells; B: phagocytosis of immune complexes by phagocytes; ↑: up-regulated gene expression

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