Low macrophage accumulation in skeletal muscle of obese type 2 diabetics and elderly subjects.
In addition to adipose tissue, recent studies suggest that skeletal muscle may also be a source of low-grade inflammation, particularly in inactive and/or overweight individuals. The aim of this study was to examine the presence of macrophages in skeletal muscle from obese subjects with type 2 diabetes (T2D) before and after a 9-month exercise program (vs. a non-exercising control group) (Study 1) and in young vs. elderly subjects (Study 2). In both studies, CD68(+) macrophages in vastus lateralis biopsies were determined by immunohistochemistry and inflammation gene expression measured. Macrophage content (%) was calculated by the number of macrophages per 100 muscle fibers. In Study 1, we found relatively low numbers (2-3%) of CD68(+) macrophages in skeletal muscle in obese T2D subjects (BMI = 37.3 ± 5.2 kg/m(2)), which were unchanged after a 9-month exercise program (P = 0.42). Similarly, in Study 2 (BMI = 27.1 ± 2.5 kg/m(2)), CD68(+) macrophages were relatively low in muscle (4-5%) and were not different between young and elderly individuals (P = 0.42). However, elderly subjects had twofold higher CD68 and CD206 gene expression (both P < 0.002) than young participants. In both studies, CD68(+) muscle macrophages were not associated with BMI. In conclusion, we found little evidence of macrophage accumulation in skeletal muscle in obese T2D subjects or in elderly individuals. A 9-month exercise program was not associated with a decrease in macrophage content.
Pennington Biomedical Research Center, Baton Rouge, LA, USA.
Charmaine S
CS
Tam
Lauren M
LM
Sparks
Darcy L
DL
Johannsen
Jeffrey D
JD
Covington
Timothy S
TS
Church
Eric
E
Ravussin
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000235:genetics / Q000378:metabolism*; D015703:Antigens, CD / Q000378:metabolism*; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism*; D001786:Blood Glucose / Q000378:metabolism*; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000378:metabolism*; D005081:Exercise Therapy / Q000379:methods; D005260:Female; D015870:Gene Expression; D005951:Glucose Tolerance Test; D006801:Humans; D007150:Immunohistochemistry; D007249:Inflammation / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008264:Macrophages / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology*; D009765:Obesity / Q000235:genetics / Q000473:pathology*; D055815:Young Adult; D000097382:CD68 Molecule
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D001786:Blood Glucose; C067980:CD68 antigen, human; D000097382:CD68 Molecule