CCL2 and chronic obstructive pulmonary disease: Data have been represented as violin box plots showing elevated levels of MCP-1 in COPD S as compared to COPD RS (p < 0.01); lower levels of IL-8 were observed in COPD RS as compared to CS (p < 0.05) and reduced TGFß1 in COPD S as compared to CS (p < 0.01) (Figure 6).