[show abstract][hide abstract] ABSTRACT: Previous studies highlight a complex relationship between lineage and phenotype for adipose tissue macrophages (ATMs), adipose stem cells (ASCs), and adipocytes, suggesting a high degree of plasticity of these cells. In the present study, using a novel co-culture system, we further characterized the interaction between ATMs, ASCs and adipocytes.
Human adipocytes and the stromal vascular fraction containing ATMs and ASCs were isolated from human adipose tissue and co-cultured for 24 hours. FACS was used to characterize ATMs and ASCs before and after co-culture. Preadipocytes generated after co-culture were characterized by immunostaining for DLK (preadipocytes), CD14 and CD68 (ATMs), CD34 (ASCs), and Nile Red staining for lipid drops. qRT-PCR was used to quantify adipogenic markers such as C/EBPα and PPARγ. A novel fluorescent nanobead lineage tracing method was utilized before co-culture where fluorescent nanobeads were internalized by CD68 (+) ATMs.
Co-culture of adipocytes with ATMs and ASCs increased the formation of new preadipocytes, thereby increasing lipid accumulation and C/EBPα and PPARγ gene expression. Preadipocytes originating after co-culture were positive for markers of preadipocytes, ATMs and ASCs. Moreover, fluorescent nanobeads were internalized by ATMs before co-culture and the new preadipocytes formed after co-culture also contained fluorescent nanobeads, suggesting that new preadipocytes originated in part from ATMs. The formation of CD34(+)/CD68(+)/DLK (+) cell spheres supported the interaction of ATMs, ASCs and preadipocytes.
Cross-talk between adipocytes, ATMs and ASCs promotes preadipocyte formation. The regulation of this novel adipogenic pathway involves differentiation of ATMs to preadipocytes. The presence of CD34(+)/CD68(+)/DLK(+) cells grouped in spheres suggest that paracrine interactions between these cell types plays an important role in the generation and proliferation of new preadipocytes. This phenomenon may reflect the in vivo plasticity of adipose tissue in which ATMs play an additional role during inflammation and other disease states. Understanding this novel pathway could influence adipogenesis, leading to new treatments for obesity, inflammation, and type 2 diabetes.
PLoS ONE 01/2011; 6(3):e17834. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Context: Adipose tissue dysfunction associated with low-grade chronic inflammation and dysregulation of adipokine secretion might significantly contribute to the pathogenesis of polycystic ovary syndrome (PCOS). Objective: The objective of the study was to determine whether the effect of TNF-alpha, IL-6, monocyte chemoattractant protein-1, or coculture of adipocytes and adipose tissue macrophages (ATMs), on the secretion of adiponectin by adipocytes, differs in PCOS compared with controls. Design and Participants: Primary cultures of sc adipocytes and coculture of adipocytes and ATMs from overweight and obese patients with PCOS and healthy control women were used. Main Outcome Measures: Adiponectin secretion by adipocytes was measured. Results: The baseline secretion of adiponectin by isolated adipocytes did not differ between PCOS and control samples. The net change in adiponectin secretion in response to IL-6, monocyte chemoattractant protein-1, and TNF-alpha differed between PCOS (decreasing) and control (increasing) adipocytes, although the difference reached significance only for TNF-alpha (P < 0.04). Coculture of isolated adipocytes and ATMs resulted in a decrease in adiponectin secretion by PCOS (P < 0.05) but not control adipocytes, and the difference between the net change in adiponectin secretion in PCOS vs. control samples was significant (P < 0.03). Conclusions: Our results suggest that adiponectin secretion by adipocytes in response to cytokines/chemokines and most notably in response to coculturing with ATMs differs between PCOS and control women, favoring greater suppression of adiponectin in PCOS. The mechanisms underlying these defects and the role of concurrent obesity remain to be determined.
The Journal of clinical endocrinology and metabolism 02/2010; 95(2):935-42. · 6.50 Impact Factor
[show abstract][hide abstract] ABSTRACT: Women with polycystic ovary syndrome (PCOS) have a myriad of phenotypic and clinical features that may guide therapeutic options for metabolic protection and ovulation induction. The use of metformin may prove beneficial in a subset of the population of women with PCOS. Hyperinsulinemia, as demonstrated by elevated insulin levels on a 2-hour 75-g load glucose tolerance test, is an important parameter in deciding whether or not to initiate metformin therapy to women with PCOS with the hope of preventing or delaying the onset of type 2 diabetes mellitus (DM). Cardiovascular risk factors including markers of subclinical inflammation, and dyslipidemia may also be improved by metformin therapy. For ovulation induction, metformin is not as effective as clomiphene citrate as first-line therapy for women with PCOS. There are no clear data to suggest that metformin reduces pregnancy loss or improves pregnancy outcome in PCOS, and it is currently recommended that metformin be discontinued with the first positive pregnancy test result, unless there are other medical indications (eg, type 2 DM). This review addresses practical management guidelines for the uses of metformin in women with PCOS.
American journal of obstetrics and gynecology 01/2009; 199(6):596-609. · 3.28 Impact Factor
[show abstract][hide abstract] ABSTRACT: Polycystic ovary syndrome (PCOS) is a diagnosis of exclusion, with other androgen excess and ovulatory dysfunction disorders to be ruled out. There are 3 principal features of the syndrome, including hyperandrogenism, ovulatory dysfunction, and polycystic ovarian morphology. These features have been included in slightly different permutations in the 3 criteria currently available to diagnose PCOS, including that of the National Institutes of Health (NIH) 1990, Rotterdam 2003, and the Androgen Excess Society 2006. Overall, at least 1 in 15 women of reproductive age will be affected by PCOS, making this disorder the most common endocrine abnormality in this age group, with a health burden of over 4 billion dollars in the United States alone.
Clinical Obstetrics and Gynecology 04/2007; 50(1):168-77. · 1.84 Impact Factor