SERPINA1 and rheumatoid arthritis: However, our results showed that the addition of 50–100 μg/mL hAAT is effective, consistent with what we observed in rheumatoid arthritis and osteoporosis mouse models.19, 21 It is possible that the disease leads to endogenous AAT insufficiency, including insufficient gene expression and loss of AAT functions, which is compensated by exogenous hAAT treatment.