Macrophage-conditioned medium inhibits the differentiation of 3T3-L1 and human abdominal preadipocytes.
OBJECTIVE
In obesity, a limited adipogenic capacity may promote adipocyte hypertrophy and increase the risk of insulin resistance and type 2 diabetes. Recent data indicate that macrophages reside within adipose tissue in obese rodents and humans. We hypothesised that secreted macrophage factors may inhibit adipogenesis.


METHODS
Conditioned media from cultured murine J774 or human THP-1 macrophages were collected, and added to either murine 3T3-L1 preadipocytes or human abdominal stromal preadipocytes from subcutaneous or omental fat depots.


RESULTS
Macrophage-conditioned medium (MacCM) strongly inhibited 3T3-L1 adipogenesis. Dose-response studies with J774-MacCM revealed that 80 and 100% of J774-MacCM completely suppressed triacylglycerol accumulation as well as the induction of fatty acid synthase, peroxisome proliferator-activated receptor gamma, CCAAT/enhancer binding protein alpha, and adiponectin. Similar inhibitory effects on 3T3-L1 preadipocytes were observed with THP-1-MacCM. Differentiation of human abdominal subcutaneous stromal preadipocytes was moderately reduced (subcutaneous>omental) by J744-MacCM. In contrast, the differentiation of both subcutaneous and omental stromal preadipocytes was completely inhibited by THP-1-MacCM, as determined on the basis of morphology and triacylglycerol accumulation, as well as fatty acid synthase and adiponectin protein expression.


CONCLUSIONS
Secreted macrophage products inhibit the differentiation of 3T3-L1 preadipocytes as well as human abdominal stromal preadipocytes.
Constant
V A
VA
Department of Medicine and of Biochemistry, University of Ottawa, Ottawa Health Research Institute, Ottawa Hospital, Ottawa, ON, Canada.
Gagnon
A
A
Landry
A
A
Sorisky
A
A
D016475:3T3 Cells / Q000166:cytology*; D000005:Abdomen; D017667:Adipocytes / Q000166:cytology*; D000818:Animals; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000502:physiology*; D002470:Cell Survival; D017077:Culture Media, Conditioned; D006801:Humans; D008264:Macrophages / Q000502:physiology*; D051379:Mice; D009000:Monocytes / Q000166:cytology
D017077:Culture Media, Conditioned