Diet-induced weight gain increases disease risk via disruption of the innate immune system. Flow cytometry is commonly used to assess the immune system; however, in mice such measurements traditionally require terminal procedures and tissue collection to generate sufficient sample. The present study refined an existing flow cytometry method to reduce the number of mice needed to longitudinally measure monocytes. CD-1 male mice were randomly assigned to one of the three groups: DS (diet-induced weight gain + sedentary), DE (diet-induced weight gain + forced treadmill running [total distance 35,755 ± 1832 m]) or NS (normal weight gain + sedentary). DS and DE consumed a 60% fat diet and NS consumed a 10% fat diet ad libitum. Saphenous vein blood samples were collected weekly for a period of six weeks and three-colour flow cytometry was used to measure changes in monocyte (CD11b+/14 +) concentration and cell-surface toll-like receptor 4 (TLR4) expression. DS (18%) and DE (17%) gained more weight than NS (P < 0.001). On a group basis, DS expressed 17% more TLR4 than DE and NS (P = 0.005). The present study demonstrates that a longitudinal survival model can be used to reduce the number of animals needed to complete flow cytometry experiments. Exercise during diet-induced weight prevented some (decreased monocyte TLR4 expression) but not all aspects of innate immune system function.
Bibliographical noteFunding Information:
This study was funded in part by a grant from the UH College of Education Faculty Research Grant Award Program (McFarlin) and a Texas ACSM Student Development Grant Award (Esposito). The authors did not have any conflict of interest associated with the present study. Esposito was the lead author and organizer of this study. Simpson was a senior author who assisted in study design and data analysis. Strohacker and Carpenter assisted in data collection/analysis and manuscript preparation. McFarlin was the senior/corresponding author and oversaw all aspects of the study.
- Innate immune dysfunction
- Toll-like receptor 4