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Obesity‐associated Inflammation Contributes to Adipose Stromal Cells Pro‐fibrotic Phenotype
Author(s) -
Springer N,
Berg M,
Seo B R,
Fischbach C
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.925.6
Subject(s) - myofibroblast , adipose tissue , stromal cell , adipocyte , inflammation , adipose tissue macrophages , macrophage , extracellular matrix , chemistry , microbiology and biotechnology , adipogenesis , lipid droplet , fibrosis , medicine , cancer research , white adipose tissue , biology , biochemistry , in vitro
Obesity is linked to breast cancer pathogenesis and physical changes to the adipose microenvironment may be important. We have observed increased myofibroblasts, cells derived from adipose stromal cells (ASC) that deposit extracellular matrix (ECM), and a correlation with macrophagic inflammation in obese fat. Our objective is to assess a functional link between inflammation, ECM stiffness and ASC differentiation. Methods Bone marrow macrophages (BMM) or RAW 264.7 cells were cultured on hydrogels mimicking the mechanical properties of lean (1 kPa) or obese (10 kPa) adipose ECM. BMM morphology and response to LPS were judged by immunofluorescence. RAW 264.7‐conditioned media (CM) tested the effect of macrophage‐secreted factors on ASC (3T3‐L1) differentiation into adipocytes and myofibroblasts. Non‐CM and TGFβ served as controls. Adipocyte and myofibroblast differentiation were quantified by lipid droplet diameter and αSMA immunofluorescence, respectively. Results BMM cultured on 10 kPa v. 1 kPa gels had increased cytoplasmic extensions and actin stress fibers. BMM from 10 kPa gels trended to reduced iNOS expression post‐LPS, which was negated by inhibiting mechanosignaling. CM increased αSMA and reduced lipid droplet size (p<0.05). Myofibroblast differentiation was similar for both stiffnesses, but CM from 10 kPa gels reduced adipogenesis more (p<0.05) and comparably to TGFβ positive control. Conclusions Stiffness alters macrophage function and macrophage‐secreted factors promote myofibroblast and hinder adipocyte differentiation of ASC. Experiments are underway to confirm macrophage mechanosignaling as a mechanism. Funding NIH T32ODO011000 & 1R01CA185293, CMM U54CA143876