Fig. 6
Gene expression and immunohistological analysis of fibrotic markers: alpha smooth muscle actin (α-SMA) (ACTA2), collagen type-1 (COL1A1) and procollagen-lysine, 2-oxoglutarate 5-dioxygenase (PLOD2) in synovial tissues isolated from 2- and 9-month-old gene-trap (Prg4GT/GT) and 2- and 9-month-old recombined gene-trap (Prg4GTR/GTR) mice. The Prg4 gene-trap allele is a loss of function allele (Prg4GT/GT) whose function is restored with Cre-excision (Prg4GTR/GTR). Recombination occurred at 3 weeks of age using intraperitoneal tamoxifen (0.1 mg/g in 100 μL corn oil vehicle) daily for 10 days. Fibrotic markers were probed using specific antibodies and staining intensities (lumens per square millimeter) were quantified. *p < 0.001; **p < 0.01; ***p < 0.05. Scale = 100 μm. a ACTA2 expression was higher in 9-month Prg4GT/GT compared to 2-month littermates and was reduced by Prg4 re-expression. b Representative images showing enhanced α-SMA immunostaining in 2- and 9-month Prg4GT/GT synovia. c Prg4 re-expression reduced α-SMA content in 2- and 9-month-old animals. d COL1A1 expression was higher in 9-month-old Prg4GT/GT animals compared to 2-month and was reduced by Prg4 re-expression. e Representative images showing enhanced collagen type-I immunostaining in 9-month-old Prg4GT/GT synovia. f Collagen type-I content was higher in 9-month-old Prg4GT/GT animals and was reduced with Prg4 re-expression. g PLOD2 expression was higher in 9-month-old Prg4GT/GT animals compared to 2-month and was reduced by Prg4 re-expression. h Representative images showing enhanced PLOD2 immunostaining in Prg4GT/GT synovia. i Prg4 re-expression reduced PLOD2 content in Prg4GT/GT synovia in 2- and 9-month-old animals