A study using VDR knockout mice reported emphysema and reduced lung function in these mice together with increased neutrophil and macrophage influx in the lung as well as upregulation of MMP-2, MMP-9 and MMP-12, suggesting that the lack of VDR activates pathways that are associated with COPD pathogenesis [78]. This evidence concerns the gene MMP9 and pulmonary emphysema.