*2.5. E*ff*ect of AT1R Deficiency on the Severity of Inflammatory Cell Infiltration in TNFtg Mice*

Since an excess of exogenous Ang II accelerated inflammatory bone destruction (Figure 2A), we investigated whether endogenous Ang II could play a role in bone destruction using AT1R-deficient arthritic mice generated by crossing TNFtg mice with AT1R-knockout (AT1R−/−) mice. AT1R deficiency did not significantly alter body weight (Figure 4A). We found that the severity of clinical arthritis (Figure 4B,C) and the extent of inflammatory cell infiltration (Figure 4D,E) were comparable between TNFtg and TNFtg/AT1R−/<sup>−</sup> mice. In addition, the severity of cartilage damage was not affected by AT1R deficiency (Figure 4D,F).

**Figure 4.** Effect of angiotensin II type 1 receptor (AT1R) deficiency on the severity of inflammatory cell infiltration in tumor necrosis factor-transgenic (TNFtg) mice. TNFtg mice were crossed with AT1R-deficient (AT1R−/−) mice. WT (*n* = 9), AT1R−/<sup>−</sup> (*n* = 7), TNFtg (*n* = 12), and TNFtg AT1R−/<sup>−</sup> (*n* = 8) male mice were analyzed at the age of 16 weeks. (**A**) Body weight at the age of 16 weeks. (**B**) Arthritis score at the age of 16 weeks. (**C**) The number of arthritic paws with an arthritis score of 2 or higher. (**D**) Representative images of stained sections around the talus bones of indicated mice; sections were stained with hematoxylin and eosin (H&E) and Safranin O; original magnification ×40. (**E**,**F**) Histological scores of inflammation (**E**) and cartilage damage (**F**). Values are the mean ± SEM. n.s., not significant. \*, *p* < 0.05.
