Table 1– Phenotype of matrix metalloproteinase (MMP)-deficient mice in different lung pathologies

Lung pathology		Deficiency	Observations	[Ref.]
COPD	Cigarette smoke exposure	MMP12	Decreased inflammation, neutrophil influx and emphysema in the lung	[13, 14]
COPD	Cigarette smoke exposure	MMP9	Normal development of cigarette smoke-induced inflammation and airspace enlargement compared	[15]
Asthma	Aspergillus fumigatus and OVA	MMP9	Disrupted trafficking of neutrophils and eosinophils into the BALF	[16]
	Aspergillus fumigatus and OVA		Massive accumulation of apoptotic cells in the lungs	[16]
	OVA		Increased airway inflammation	[17]
	German cockroach frass		Increased airway inflammation	[18]
	OVA		Impaired cellular infiltration and bronchial hyperresponsiveness	[19]
	OVA		Impaired accumulation of airway wall dendritic cells	[20]
	Aspergillus fumigatus and OVA	MMP2	Disrupted trafficking of eosinophils into the BALF	[16, 21]
			Massive accumulation of apoptotic cells in the lungs
			Increased susceptibility to asphyxiation
	Aspergillus fumigatus and OVA	MMP9/MMP2	MMP9 is the dominant airway MMP controlling inflammatory cell egression	[16]
	Cockroach antigen	MMP12	Reduced inflammatory injury	[22]
	House mite	MMP8	Airway hyperresponsiveness and decreased levels of soluble IL-13Rα2	[23]
ILD	Bleomycin	MMP8	Less fibrosis	[24]
	Bleomycin	MMP8	Decreased IL-10 processing	[24]
	Bleomycin	MMP12	No effect	[25]
	Fas-activating monoclonal antibody		Decreased expression of profibrotic genes	[26]
	Bleomycin	MMP9	Reduced alveolar bronchiolisation	[27]
	Bleomycin	MMP7	Impaired efflux of neutrophils into the alveolar space	[28]
			Reduced lethality
			Decreased alveolar fibrosis at later stages
	Bleomycin		Reduced fibrosis	[29]
ALI	High-pressure ventilation	MMP8	Decreased lung oedema and permeability	[30]
	High-pressure ventilation		Diminished histological injury	[30]
	Mechanical ventilation		Increased alveolar permeability	[31]
	LPS		Accumulation of PMN cells in alveolar space	[32]
	Bleomycin		Accumulation of PMN cells in alveolar space	[33]
			Increased alveolar capillary barrier injury
			Increased lung elastance
			Increased mortality
	LPS	MMP9	No protection	[34]
	LPS		Development of emphysema	[34]
	Ozone		Increased protein content and numbers of neutrophils and epithelial cells in BALF	[35]
	Ozone		Increased KC and MIP2 levels in BALF	[35]
	Ozone	MMP7	No effect	[35]
	Hyperoxia	MMP13	Increased inflammation because of the lack of MCP1 cleavage	[36]
	Immunoglobulin G immune complex	MMP3	Reduced lung injury	[37]
	Immunoglobulin G immune complex	MMP3	Reduction in leukocyte recruitment	[37]
Lung cancer	MMTV-PyMT	MMP13	No effect on development of lung metastasis	[38]
	B16-BL6 melanoma	MMP9	Reduced number of metastatic colonies	[39]
	Lewis lung carcinoma		Reduced number of metastatic colonies	[39]
	MMTV-PyVT		Decreased angiogenesis	[40]
	MMTV-PyVT		Decrease in lung tumour burden	[40]
	MMTV-PyVT	MMP7	No effect on development of lung metastases	[40]
	B16-BL6 melanoma	MMP2	Reduced tumour-induced angiogenesis	[41]
	Lewis lung carcinoma	MMP2	Reduced tumour-induced angiogenesis	[41]
	Lewis lung carcinoma	MMP12	Increased number of pulmonary metastases	[42]
BOS	Heterotopic airway transplant model	MMP8	Reduced neutrophil influx and collagen deposition	[43]
BOS	Heterotopic murine tracheal allografts	MMP9	Reduced neutrophil influx and collagen deposition	[44]
CLD	Pulmonary overexpression of human mature IL-1β	MMP9	Increased IL-1β-induced lung injury	[45]

COPD: chronic obstructive pulmonary disease; ILD: interstitial lung diseases; ALI: acute lung injury; BOS: bronchiolitis obliterans syndrome; CLD: chronic lung disease of prematurity; OVA: ovalbumin; BALF: bronchoalveolar lavage fluid; IL: interleukin; LPS: lipopolysaccharide; PMN: polymorphonuclear; KC: keratinocyte chemoattractant; MIP2: macrophage inflammatory protein-2; MCP1: monocyte chemoattractant protein-1; MMTV-PyMT, MMTV-PyVT: mouse mammary tumour virus with polyoma middle T-antigen promoter, mouse mammary tumour virus.