8159 Single Nuclei RNA-Sequencing Reveals Novel Cellular Diversity in Human Neck Adipose Tissue
Authors: Camara Henrique , David Kodani Sean , Yang Shiyi , Efthymiou Vissarion , An Kevin , Gupta Anushka , Shamsi Farnaz , Streets Aaron , Elizabeth Patti Mary , Tseng Yu-Hua 
Published: October 2024

Abstract
Disclosure: H. Camara: None. S.D. Kodani: Employee; Self; Hoxton Farm. S. Yang: None. V. Efthymiou: None. K. An: None. A. Gupta: None. F. Shamsi: None. A. Streets: None. M.E. Patti: Advisory Board Member; Self; Fractyl Laboratories. Consulting Fee; Self; AstraZeneca, Hamni, MBX Biosciences. Grant Recipient; Self; Dexcom. Y. Tseng: Consulting Fee; Self; LyGenesis. Other; Self; BioHaven.
Adipose tissue plays a crucial role in maintaining metabolic health. It fulfills distinct functions through two types of fat: white adipose tissue (WAT), the primary site of triglyceride storage, and brown adipose tissue (BAT) along with related beige fat, specializing in thermogenic energy expenditure. Despite the scarcity of BAT in humans, these thermogenic adipocytes efficiently utilize glucose and triglycerides and act as an endocrine organ by secreting batokines. Hence, increased BAT activity is associated with improved metabolic health in humans. In adults, thermogenic adipose tissue is localized in deep neck planes, exhibiting a gradient from white to beige/brown from superficial to deep layers. Mounting evidence suggests the diverse cell types within the adipose tissue and their dynamic interactions play an important role in its versatile functions. To understand the cellular compositions of human adipose tissue and directly compare the differences between human BAT vs. WAT, we collected 30 paired samples of superficial, intermediate and deep human neck adipose tissue from 15 participants who underwent anterior cervical discectomy fusion or thyroid surgery and subjected the frozen tissues to single-nucleus RNA sequencing (snRNA-seq). The integration of the samples yielded 41,337 good-quality nuclei. As expected, white adipocytes (WAd) were the dominant cell type, comprising 38% of the total cells captured. Further analysis of the WAd cluster revealed increased expression of brown adipocyte-associated genes, such as EBF2 and COBL, and enrichment of oxidative phosphorylation pathway score in cells from deep neck samples, indicating increased thermogenic potential. Bona fide brown adipocytes (BAds), marked by the expression of PPARGC1A, were predominantly located in the deep neck samples (&gt;80%) but comprised less than 2% of the dataset. Despite their low numbers, cell-cell communication analysis by CellChat predicted that BAds account for most of the communication events within this niche, highlighting their endocrine importance. snRNA-seq also captured non-adipocyte cells, including adipocyte progenitors, smooth muscle, immune, Schwann and neuron-associated cells. Among these, a novel Neuron-Associated Cell-1, marked by the expression of CNTNAP2, emerged as the second most abundant in the dataset (∼10% of total). Another neuron-associated cell population marked by expression of DNAH11, though less abundant (∼1%), was enriched in deep neck samples, potentially regulating the high levels of thermogenic potential in this region. Taken together, the identified subpopulations and their gene expression profiles offer new insights into the tissue's role in metabolic regulation. This knowledge could be pivotal for developing targeted therapies for obesity and related disorders.
Presentation: 6/1/2024