Diminution of lung and bone metastasis in arthritic PyV MT mice treated with anti-IL-17A antibody. A and B: Percentage of lung (A) and bone (B) metastasis in PyV MT mice Statistics: The difference in lung metastasis between untreated and IgG treated versus anti-IL-17 treated is significant (*p = 0.006) and difference between untreated PyV MT + AA versus PyV MT with no AA is also significant (**p = 0.001). Although fewer animals developed bone metastasis with anti-IL-17 antibody treatment, significance was not reached. However there was a significant difference in bone metastasis between PyVMT mice with no AA versus PyVMT mice with AA (*p = 0.002) C: Representative images of H& E (200x magnification) of lungs to confirm metastasis in PyV MT mice with no AA (i), PyV MT mice with AA treated with control IgG antibody (ii) or with anti-IL-17A antibody (iii). D: Representative X-ray images of metastatic bone lesions in PyV MT mice with no AA (i); arthritic PyV MT model treated with control antibody (ii) or anti-IL-17A antibody (iii) (A-D: N = 6–8 mice) Arrows point to a metastatic site in the proximal humerus; note the prominent lucency in the proximal region, reflecting extensive bone loss at this site. Ei-iii: Representative images of pancytokeratin staining of bone tissue to confirm metastasis in PyV MT mice with no AA (i), PyV MT mice with AA treated with control IgG antibody (ii) or with anti-IL-17A antibody (iii).