Expansion and inflammation of white adipose tissue - focusing on adipocyte progenitors

Abstract

Adipose tissue is an important organ in our body, participating not only in energy metabolism but also immune regulation. It is broadly classified as white (WAT) and brown (BAT) adipose tissues. WAT is highly heterogeneous, composed of adipocytes, various immune, progenitor and stem cells, as well as the stromal vascular populations. The expansion and inflammation of WAT are hallmarks of obesity and play a causal role in the development of metabolic and cardiovascular diseases. The primary event triggering the inflammatory expansion of WAT remains unclear. The present review focuses on the role of adipocyte progenitors (APS), which give rise to specialized adipocytes, in obesity-associated WAT expansion, inflammation and fibrosis.

Distinct Adipogenic and Fibrogenic Differentiation Capacities of Mesenchymal Stromal Cells from Pancreas and White Adipose Tissue

“…Our study identified marked variations in the expression profile and differentiation characteristics between MSCs isolated from pancreas (pMSCs) and iWAT (iwatMSCs). In general, MSCs are able to differentiate into several lineages, e.g., adipocytes and fibroblasts [3,23]. As expected, iwatMSCs exhibit a major potential to differentiate into adipocytes.…”

“…In obesity, WAT expansion occurs through (i) lipid filling within existing fat cells (adipocyte hypertrophy) and (ii) formation of new adipocytes from mesenchymal stromal cells (MSCs) with adipogenic differentiation potential (adipocyte hyperplasia), also well-known as adipogenic precursor cells (APC) [2]. When MSCs exhibit a low ability to differentiate into mature fat-storing adipocytes, the rate of adipocyte hypertrophy is increased [2,3]. However, excessive levels of circulating lipids combined with a limited adipocyte storage capacity result in ectopic fat accumulation in non-adipose tissue organs such as liver and muscle, taking the shape of intra-hepatocyte and intra-myocyte lipid droplet stores or as bona fide mature adipocytes interspersed within bone tissue, and the pancreas [4][5][6][7][8].…”

Inhibition of Lipid Accumulation and Cyclooxygenase-2 Expression in Differentiating 3T3-L1 Preadipocytes by Pazopanib, a Multikinase Inhibitor

“…In the present study, of interest, we found that treatment with pazopanib at 5–15 μM for 4 h largely inhibits TNF-α-induced expression of COX-2 in both 3T3-L1 preadipocytes and differentiated cells. It is documented that inflammation confers expansion of the white adipose tissues by increasing adipogenesis, though the primary event triggering this is not fully understood [ 59 ]. It is assumed that acute and chronic expression of inflammatory mediators in the white adipose tissues and (pre)adipocytes partly leads to the development of obesity [ 58 ].…”

Cudratricusxanthone A Inhibits Lipid Accumulation and Expression of Inducible Nitric Oxide Synthase in 3T3-L1 Preadipocytes

“…Although not directly related to the current study, we have previously reported that CTXA protects sepsis-triggered renal damage in mice by inhibiting induction of iNOS expression [ 56 ] and attenuates sepsis-induced liver injury partially through the reduced expression of inflammatory cytokines including TNF-α [ 57 ], supporting this natural compound’s anti-inflammatory effect via iNOS and TNF-α down-regulation in vivo. It is known that inflammation contributes to the expansion of white adipocyte tissues by increasing adipogenesis, though the primary event triggering this remains unclear [ 58 ]. Overexpression and hyper-activation of inflammatory mediators in white adipose tissues partly leads to the development of obesity.…”