Isolation and Flow Cytometric Analysis of the Stromal Vascular Fraction Isolated from Mouse Adipose Tissue

Activation of a non-neuronal cholinergic system in visceral white adipose tissue of obese mice and humans

BACKGROUND AND OBJECTIVES

Since white adipose tissue (WAT) lacks parasympathetic cholinergic innervation, the source of the acetylcholine (ACh) acting on white adipocyte cholinergic receptors is unknown. This study was designed to identify ACh-producing cells in mouse and human visceral WAT and to determine whether a non-neuronal cholinergic system becomes activated in obese inflamed WAT.

METHODS

Mouse epididymal WAT (eWAT) and human omental fat were studied in normal and obese subjects. The expression of the key molecules involved in cholinergic signaling was evaluated by qRT-PCR and western blotting whereas their tissue distribution and cellular localization were investigated by immunohistochemistry, confocal microscopy and in situ hybridization. ACh levels were measured by liquid chromatography/tandem mass spectrometry. The cellular effects of ACh were assessed in cultured human multipotent adipose-derived stem cell (hMADS) adipocytes.

RESULTS

In mouse eWAT, diet-induced obesity modulated the expression of key cholinergic molecular components and, especially, raised the expression of choline acetyltransferase (ChAT), the ACh-synthesizing enzyme, which was chiefly detected in interstitial macrophages, in macrophages forming crown-like structures (CLSs), and in multinucleated giant cells (MGCs). The stromal vascular fraction of obese mouse eWAT contained significantly higher ACh and choline levels than that of control mice. ChAT was undetectable in omental fat from healthy subjects, whereas it was expressed in a number of interstitial macrophages, CLSs, and MGCs from some obese individuals. In hMADS adipocytes stressed with tumor necrosis factor α, ACh, alone or combined with rivastigmine, significantly blunted monocyte chemoattractant protein 1 and interleukin 6 expression, it partially but significantly, restored adiponectin and GLUT4 expression, and promoted glucose uptake.

CONCLUSIONS

In mouse and human visceral WAT, obesity induces activation of a macrophage-dependent non-neuronal cholinergic system that is capable of exerting anti-inflammatory and insulin-sensitizing effects on white adipocytes.

Clostridium butyricum Inhibits Fat Deposition via Increasing the Frequency of Adipose Tissue-Resident Regulatory T Cells

SCOPE

Clostridium butyricum (CB) exerts beneficial actions in several disorders. However, the impact and molecular cues of CB in fat metabolism remain elusive. This study demonstrates the CB inhibition of fat deposition by increasing the relative number of adipose tissue-resident Treg cells (aTregs).

METHODS AND RESULTS

CB is administered orally to wild type (WT) mice fed with chow diet, which decrease fat deposition and adipogenic gene expression, associating with elevated serum levels of butyrate. Sodium butyrate (SB) feeding mimics the CB suppression of fat accumulation. Of note, the frequency of aTregs in both the CB and SB treatments, analyzed by flow cytometry, is markedly increased, accompanied by activated Wnt10b expression in white adipose tissues. However, CB and SB fail to inhibit fat deposition in Wnt10b-KO mice. Intriguingly, CB and SB are able to alleviate the obesity, fatty liver, and glucose abnormalities in high fat diet (HFD)-fed WT mice.

CONCLUSIONS

These findings suggest that CB, through its metabolite butyrate, inhibits fat deposition via potentiating aTreg cell generation, and support the option of CB and SB for therapeutic interventions in obesity and related disorders.

A FACS-based approach to obtain viable eosinophils from human adipose tissue

Eosinophils have been widely investigated in asthma and allergic diseases. More recently, new insights into the biology of these cells has illustrated eosinophils contribute to homeostatic functions in health such as regulation of adipose tissue glucose metabolism. Human translational studies are limited by the difficulty of obtaining cells taken directly from their tissue environment, relying instead on eosinophils isolated from peripheral blood. Isolation techniques for tissue-derived eosinophils can result in unwanted cell or ribonuclease activation, leading to poor cell viability or RNA quality, which may impair analysis of effector activities of these cells. Here we demonstrate a technique to obtain eosinophils from human adipose tissue samples for the purpose of downstream molecular analysis. From as little as 2 g of intact human adipose tissue, greater than 10⁴ eosinophils were purified by fluorescence-activated cell sorting (FACS) protocol resulting in ≥ 99% purity and ≥ 95% viable eosinophils. We demonstrated that the isolated eosinophils could undergo epigenetic analysis to determine differences in DNA methylation in various settings. Here we focused on comparing eosinophils isolated from human peripheral blood vs human adipose tissue. Our results open the door to future mechanistic investigations to better understand the role of tissue resident eosinophils in different context.