Granzyme-A deficiency attenuates experimental osteoarthritis in mice, but perforin deficiency does not

OBJECTIVES: This study aims to assess the development of osteoarthritis (OA) in granzyme A- (gzmA) and B- (gzmB) and perforin- (perf) knockout mice. MATERIALS AND METHODS: A total of 75 male and female C57BL/6 (eight to nine-week-old) mice were allocated to: gzmA-deficient (gzmA-/-) (11 females, 8 males), gzmB-deficient (gzmB-/-) (9 females, 8 males), perf-deficient (perf-/-) (10 females, 9 males), and control group (10 females, 10 males). Osteoarthritis was induced in the right knee by instability of the meniscus medial ligament. Sham surgery was practiced in the left knee. Knee samples obtained eight weeks after surgery were stained (Safranin-O) and blindly scored in lateral and medial femur and tibia using the Osteoarthritis Research Society International scale (OARSI) (from Grade 0, cartilage intact to 6, deformation), (five stages from 0, no OA to 4, >50% surface involvement); OARSI score (grade x stage); and a semi-quantitative scale from Grade 0 (normal) to 6 (cartilage erosion >80%). RESULTS: Significantly higher values in all scales in the right knees compared to the left knees in male and female mice were observed (p<0.05). Males of all strains showed in the right knee higher values than females on all scales. Deficiency of perforin did not modify OA severity in any sex. The gzmA-/- females presented less degenerative changes than the other groups. CONCLUSION: Our study results show that sex plays an important role in the development of experimental OA in mice. Deficiency of gzmA can protect from the development of OA in female mice.