Spontaneous air space enlargement in the lungs of mice lacking tissue inhibitor of metalloproteinases-3 (TIMP-3)
Kevin J. Leco, … , Tak W. Mak, Rama Khokha
Kevin J. Leco, … , Tak W. Mak, Rama Khokha
Published September 15, 2001
Citation Information: J Clin Invest. 2001;108(6):817-829. https://doi.org/10.1172/JCI12067.
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Article

Spontaneous air space enlargement in the lungs of mice lacking tissue inhibitor of metalloproteinases-3 (TIMP-3)

Abstract

Tissue inhibitors of metalloproteinases regulate ECM degradation by matrix metalloproteinases (MMPs). We have developed a mouse line deficient for tissue inhibitor of metalloproteinases-3 (TIMP-3), the only TIMP known to reside within the ECM. Homozygous Timp-3–null animals develop spontaneous air space enlargement in the lung that is evident at 2 weeks after birth and progresses with age of the animal. As early as 13 months of age animals become moribund. Lung function, measured by carbon monoxide uptake, is impaired in aged null animals. Lungs from aged null animals have reduced abundance of collagen, enhanced degradation of collagen in the peribronchiolar space, and disorganization of collagen fibrils in the alveolar interstitium, but no increase in inflammatory cell infiltration or evidence of fibrosis in comparison with controls. Using in situ zymography, we show that lungs from aged null animals have heightened MMP activity over wild-type and heterozygotic animals. Finally, TIMP-3–null fibroblast cultures demonstrate enhanced destruction of ECM molecules in vitro. We propose that the deletion of TIMP-3 results in a shift of the TIMP/MMP balance in the lung to favor ECM degradation, culminating in incapacitating illness and a shorter life span.

Authors

Kevin J. Leco, Paul Waterhouse, Otto H. Sanchez, Katrina L.M. Gowing, A. Robin Poole, Andrew Wakeham, Tak W. Mak, Rama Khokha

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Generation of TIMP-3–null animals. (a) Targeting strategy: Approximately...
Generation of TIMP-3–null animals. (a) Targeting strategy: Approximately 700 bp of Timp-3 promoter sequence and 6 kb from exons 2 and 3 (including the second intron) were placed on either side of a NeoR cassette in the opposite transcriptional orientation. (b) Southern blot analysis: A flanking Timp-3 or NeoR cDNA probe detected the mutant allele (18 kb) in heterozygote ES cells and heterozygote and null animals. (c) Northern blot analysis: Abundance of the Timp-3 mRNA was reduced in heterozygote and null animals while expression of a NeoR mRNA (evidently under the tissue-specific direction of the TIMP-3 promoter) was detected in heterozygote and null animals. (d) Reverse zymographic analysis: TIMP-3 protein was reduced in heterozygotic kidney extracts by approximately half compared with wild-type and was absent in the null extracts.