OBJECTIVE: To examine differences in genes involved in fat metabolism, energy homeostasis, adipogenesis, and inflammation between endstage and early-stage knee osteoarthritis (OA) infrapatellar fat pads (IFP). METHODS: Twenty-nine endstage and 5 early-stage primary OA IFP were harvested at knee surgery. Total RNA was extracted, labeled, and hybridized to whole-genome expression arrays. Unsupervised analysis of all samples using principal components analysis or 2-way hierarchical clustering showed groupings based on tissue source and disease. Statistical testing identified sets of genes that displayed differences between the 2 fat types. Western blot analysis was performed for protein expression of an identified gene of interest. RESULTS: The 29 IFP demonstrated an elevation in the expression of adipokines such as adiponectin and leptin. A statistically significant increased expression was seen for genes of adipogenesis, such as peroxisome proliferator-activated receptor-γ (PPAR-γ), diacylglycerol acyltransferase 2 (DGAT2), cluster of differentiation (CD36), and thyroid hormone responsive spot (THRSP) in the severe OA fat pads as compared to the controls. A subset of 5 patients in the endstage OA group were consistently similar in gene expression to early OA tissue. Protein expression of PPAR-γ2 was 5.4-fold and PPAR-γ1 was 1.4-fold greater in endstage versus early OA tissue. CONCLUSION: Endstage OA fat pads demonstrated a significant upregulation of genes for fat metabolism and energy homeostasis and a mixed result for inflammatory cytokines.
OBJECTIVE: To examine differences in genes involved in fat metabolism, energy homeostasis, adipogenesis, and inflammation between endstage and early-stage knee osteoarthritis (OA) infrapatellar fat pads (IFP). METHODS: Twenty-nine endstage and 5 early-stage primary OA IFP were harvested at knee surgery. Total RNA was extracted, labeled, and hybridized to whole-genome expression arrays. Unsupervised analysis of all samples using principal components analysis or 2-way hierarchical clustering showed groupings based on tissue source and disease. Statistical testing identified sets of genes that displayed differences between the 2 fat types. Western blot analysis was performed for protein expression of an identified gene of interest. RESULTS: The 29 IFP demonstrated an elevation in the expression of adipokines such as adiponectin and leptin. A statistically significant increased expression was seen for genes of adipogenesis, such as peroxisome proliferator-activated receptor-γ (PPAR-γ), diacylglycerol acyltransferase 2 (DGAT2), cluster of differentiation (CD36), and thyroid hormone responsive spot (THRSP) in the severe OA fat pads as compared to the controls. A subset of 5 patients in the endstage OA group were consistently similar in gene expression to early OA tissue. Protein expression of PPAR-γ2 was 5.4-fold and PPAR-γ1 was 1.4-fold greater in endstage versus early OA tissue. CONCLUSION: Endstage OA fat pads demonstrated a significant upregulation of genes for fat metabolism and energy homeostasis and a mixed result for inflammatory cytokines.
Authors: Aarón Leonardo Pogacnik Murillo; Felix Eckstein; Wolfgang Wirth; Daniel Beavers; Richard F Loeser; Barbara J Nicklas; Shannon L Mihalko; Gary D Miller; David J Hunter; Stephen P Messier Journal: Cells Tissues Organs Date: 2017-02-22 Impact factor: 2.481
Authors: Magdalena Richter; Tomasz Trzeciak; Maciej Owecki; Andrzej Pucher; Jacek Kaczmarczyk Journal: Int Orthop Date: 2015-02-26 Impact factor: 3.075
Authors: Zhenhong Ni; Siru Zhou; Song Li; Liang Kuang; Hangang Chen; Xiaoqing Luo; Junjie Ouyang; Mei He; Xiaolan Du; Lin Chen Journal: Bone Res Date: 2020-06-19 Impact factor: 13.567