Lung involvement prior the onset of arthritis; increase in ankle thickness with high levels of anti‐CII antibodies; inflammatory cell infiltration(T cells and CD11bhi macrophages), ACPAs, C3 deposited in the subpleural region of the lung, increased cytokines of IL‐1β, IL‐6, IFN‐γ, TNF‐α levels, IL‐4, IL‐17, CCL3, and CCL4. Here, C3 is linked to arthritic joint disease.