Immune Netw.  2016 Jun;16(3):189-194. 10.4110/in.2016.16.3.189.

Differential Chemokine Signature between Human Preadipocytes and Adipocytes

• Ignacio RM
• Gibbs CR
• Lee ES
• Son DS

• KMID: 2299793
• DOI: http://doi.org/10.4110/in.2016.16.3.189

Abstract

Obesity is characterized as an accumulation of adipose tissue mass represented by chronic, low-grade inflammation. Obesity-derived inflammation involves chemokines as important regulators contributing to the pathophysiology of obesity-related diseases such as cardiovascular disease, diabetes and some cancers. The obesity-driven chemokine network is poorly understood. Here, we identified the profiles of chemokine signature between human preadipocytes and adipocytes, using PCR arrays and qRT-PCR. Both preadipocytes and adipocytes showed absent or low levels in chemokine receptors in spite of some changes. On the other hand, the chemokine levels of CCL2, CCL7-8, CCL11, CXCL1-3, CXCL6 and CXCL10-11 were dominantly expressed in preadipocytes compared to adipocytes. Interestingly, CXCL14 was the most dominant chemokine expressed in adipocytes compared to preadipocytes. Moreover, there is significantly higher protein level of CXCL14 in conditioned media from adipocytes. In addition, we analyzed the data of the chemokine signatures in adipocytes obtained from healthy lean and obese postmenopausal women based on Gene Expression Omnibus (GEO) dataset. Adipocytes from obese individuals had significantly higher levels in chemokine signature as follows: CCL2, CCL13, CCL18-19, CCL23, CCL26, CXCL1, CXCL3 and CXCL14, as compared to those from lean ones. Also, among the chemokine networks, CXCL14 appeared to be the highest levels in adipocytes from both lean and obese women. Taken together, these results identify CXCL14 as an important chemokine induced during adipogenesis, requiring further research elucidating its potential therapeutic benefits in obesity.

Keyword

Chemokine; Adipogenesis; Obesity; Human adipocyte

MeSH Terms

Adipocytes*
Adipogenesis
Adipose Tissue
Cardiovascular Diseases
Chemokines
Culture Media, Conditioned
Dataset
Female
Gene Expression
Hand
Humans*
Inflammation
Obesity
Polymerase Chain Reaction
Receptors, Chemokine
Chemokines
Culture Media, Conditioned
Receptors, Chemokine

Figure

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  Figure 1 Chemokine receptor signature in human preadipocytes and adipocytes. (A) Representative images of human adipocytes during adipogenesis. Human preadipocyte and differentiated adipocytes were visualized under a digital inverted microscope at 20 X magnification. Human preadipocytes show long, thin and flatted cells, while human adipocytes show differentiated fat cells in spherical form. (B) Comparison of chemokine ligands in preadipocytes vs. adipocytes. A PCR array for chemokine receptors was performed by using total RNA isolated from nondifferentiated (preadipocytes) and differentiated cells (adipocytes). Different colors indicate the average cycle threshold with expressions that ranged from >35 to <25. Expression levels of chemokine receptors were defined as absent (>35), low (30-35) and high (<30) on average threshold cycles. Chemokines with a >2-fold increase (*) or decrease (#) were recognized as the major differences between preadipocytes and adipocytes.

• 

  Figure 2 Chemokine ligand signature in human preadipocytes and adipocytes. (A) Comparison of chemokine ligands in preadipocytes and adipocytes using PCR array containing complementary sequences for human chemokine ligand genes. Different colors indicate the average cycle threshold with expressions that ranged from >35 to <25. Expression levels of chemokines were defined as absent (>35), low (30-35) and high (<30) on average threshold cycles. Chemokines with a >2-fold increase (*) or decrease (#) were recognized as the major differences between preadipocytes and adipocytes. (B) Changes in mRNA expression of CCL2, CCL7, CCL8, CXCL6, CXCL10 and (C) CXCL14 were confirmed using specific PCR primer sets by qRT-PCR. Fold changes were calculated as a relative value after setting the first sample of adipocytes as a control group (1.0). Also, secreted CXCL14 in conditioned media from preadipocytes and adipocytes was assessed by ELISA. Experiments values for PCR array are the means from duplicate experiments, while experiments for qRT-PCR were performed at least in triplicate. All data value are presented as mean±SEM. * and # indicates significant increase or decrease (p≤0.05), respectively when tested with Student's t test.

• 

  Figure 3 Profiles of chemokine network in adipose tissues between lean and obese postmenopausal women. (A) Expression levels of chemokine ligands and receptors in subcutaneous adipose tissues between lean and obese women using microarray data via Gitools. (B) Intensity of chemokine network for statistical analysis. All values are presented as mean. Red and blue letters in chemokine signature indicate significant increase or decrease in obese women (p≤0.05), respectively, as tested with Student's t test.

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