Title
Lack of high BMI-related features in adipocytes and inflammatory cells in the infrapatellar fat pad (IFP)
Author
de Jong, A.J.
Klein-Wietinga, I.R.
Andersen, S.N.
Kwekkeboom, J.C.
Herb-van Toorn, L.
de Lange-Brokaar, B.J.E.
van Delft, D.
Garcia, J.
Wei, W.
van der Heide, H.J.L.
Bastiaanen-Jenniskens, Y.M.
van Osch, G.J.V.M.
Zuurmond, A.M.
Stojanovic-Susulic, V.
Nelissen, R.G.
Toes, R.E.M.
Kloppenburg, M.
Ioan-Facsinay, A.
Publication year
2017
Abstract
Background. Obesity is associated with the development and progression of osteoarthritis (OA). Although the infrapatellar fat pad (IFP) could be involved in this association, due to its intracapsular localization in the knee joint, there is currently little known about the effect of obesity on the IFP. Therefore, we investigated cellular and molecular body mass index (BMI)-related features in the IFP of OA patients. Methods. Patients with knee OA (N = 155, 68% women, mean age 65 years, mean (SD) BMI 29.9 kg/m2 (5.7)) were recruited: IFP volume was determined by magnetic resonance imaging in 79 patients with knee OA, while IFPs and subcutaneous adipose tissue (SCAT) were obtained from 106 patients undergoing arthroplasty. Crown-like structures (CLS) were determined using immunohistochemical analysis. Adipocyte size was determined by light microscopy and histological analysis. Stromal vascular fraction (SVF) cells were characterized by flow cytometry. Results. IFP volume (mean (SD) 23.6 (5.4) mm3) was associated with height, but not with BMI or other obesity-related features. Likewise, volume and size of IFP adipocytes (mean 271 pl, mean 1933 um) was not correlated with BMI. Few CLS were observed in the IFP, with no differences between overweight/obese and lean individuals. Moreover, high BMI was not associated with higher SVF immune cell numbers in the IFP, nor with changes in their phenotype. No BMI-associated molecular differences were observed, besides an increase in TNFalpha expression with high BMI. Macrophages in the IFP were mostly pro-inflammatory, producing IL-6 and TNFalpha, but little IL-10. Interestingly, however, CD206 and CD163 were associated with an anti-inflammatory phenotype, were the most abundantly expressed surface markers on macrophages (81% and 41%, respectively) and CD163+ macrophages had a more activated and pro-inflammatory phenotype than their CD163- counterparts. Conclusions. BMI-related features usually observed in SCAT and visceral adipose tissue could not be detected in the IFP of OA patients, a fat depot implicated in OA pathogenesis.
Subject
ELSS - Earth, Life and Social Sciences
Life
Healthy Living
Biomedical Innovation
Osteoarthritis
Infrapatellar fat pad
Obesity
Inflammation
Macrophages
MHR - Metabolic Health Research
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DOI
https://doi.org/10.1186/s13075-017-1395-9
TNO identifier
779167
Source
Arthritis Research and Therapy, 19 (19)
Document type
article