Fig. 1

Inflammation-amplifying (InfA) cells expand in aged and osteoarthritic cartilage in mice. A Schematic showing strategy for isolation of cells of InfA cells from mice knee joints. B FACS strategy for isolation of TNF-R2 and IL1R1 double-positive InfA cells. C FACS plots showing InfA population in 3-mo and 12-month-old mice; cell numbers were quantified and are represented in the bar graph as a percentage of the total number of analyzed cells. D Schematic showing induction of OA using tibia loading model and collection of limbs for analysis at 8 weeks post-injury, representative sagittal sections of knee joint cartilage from tibia-loaded and control limbs showing the presence of p-Jnk + cells (InfA cells) in the cartilage, quantification in the bar graph on the right. Significance was calculated using Student’s t test with Welch’s correction. *p < 0.05, **p < 0.01, ***p < 0.001, scale bar = 200 μm (D)—left panel, scale bar = 100 μm (D)—right panel