Fat depot-specific differences of macrophage infiltration and cellular senescence in obese bovine adipose tissues

Abstract

Obesity is associated with the chronic inflammation and senescence of adipose tissues. Macrophage is a key mediator of chronic inflammation that infiltrates obese adipose tissue and stimulates metabolic disorders. However, the fat depot-specific differences of macrophage infiltration and senescence, especially the influence on intramuscular adipose tissue, have remained unclear. We investigated the fat depot-specific differences of macrophage infiltration and senescence in obese bovine adipose tissue from three different anatomical sites (subcutaneous, intramuscular and visceral). Macrophage infiltrations and crown-like structures were observed in visceral adipose tissue, although there were few macrophages in subcutaneous and intramuscular adipose tissues. The positive reaction of senescence marker SA-βgal activity was observed in visceral adipose tissue. In contrast, the activity of SA-βgal in subcutaneous and intramuscular adipose tissues were low. The expression of p53 gene, the master regulator of cellular senescence, in visceral adipose tissue was higher than that of subcutaneous and intramuscular adipose tissue. At the cellular level, p53 gene expression was negatively correlated with the size of subcutaneous adipocytes. In contrast, p53 gene expressions were positively correlated with the size of intramuscular and visceral adipocytes. These results indicate that anatomical sites of obese adipose tissue affect macrophage infiltration and the senescent state in a fat depot-specific manner.

Moderation of mitochondrial respiration mitigates metabolic syndrome of aging

“…The roles of mitochondria in age-associated fat mass and linked diseases such as diabetes have been carefully examined for decades (18)(19)(20)(21). Increased adipose tissue is not merely a reservoir of excess nutrients (21,22), but rather an active and dynamic organ capable of expressing harmful inflammatory factors which accelerate metabolic syndrome of aging, including obesity, type 2 diabetes mellitus (T2DM), and cardiovascular diseases (22)(23)(24)(25)(26)(27). Therefore, curing obesity, diabetes, and prediabetic irregularities are priorities in promoting healthy aging and mitigating metabolic syndrome.…”

Fat depot‐specific effects of body fat distribution and adipocyte size on intramuscular fat accumulation in Wagyu cattle

“…In obese humans and rodents, increasing the number of macrophage infiltration into adipose tissue stimulate the inflammation of adipose tissue (Altintas et al., 2011; Cinti et al., 2005). We previously showed that the number of macrophage infiltration into visceral adipose tissue was higher than that of subcutaneous and intramuscular adipose tissues in fattening Wagyu (Yamada, Kamiya, Higuchi, & Nakanishi, 2018). These results suggest that increased inflammation in visceral adipose tissue of fattening Wagyu might affect the limitation of energy storage in visceral depots.…”

Breed differences in macrophage infiltration and senescence state in adipose tissues of Wagyu and Holsteins

“…Stained adipose tissues were photographed using a digital camera (DMC‐TZ85; Panasonic). SA‐βgal‐positive adipocytes within adipose tissues form a blue‐stained area (Minamino et al., 2009; Yamada et al., 2018).…”

“…mRNA expression was analyzed using real‐time PCR as described previously (Yamada, Higuchi, & Nakanishi, 2014; Yamada, Kamiya, & Higuchi, 2018). In brief, total RNA was extracted from adipose tissue using a RiboPure Kit (Ambion).…”

“…SA‐βgal staining was examined using the Senescence Detection Kit (BioVision Co.) as described previously (Yamada et al., 2018). In brief, adipose tissue samples were incubated within X‐gal staining solution, followed by washing with ice‐cold PBS to stop the enzymatic reaction.…”