Microarray gene analysis demonstrated significantly
increased expression of MMP-7 in patients with IPF (fourfold) and NSIP
(33-fold) compared to normal lung in which low levels of MMP-7 were
observed. Interestingly, other metalloproteinases, such as MMP-2,
MMP-9, and TIMP-1, were not differentially expressed between normal and
diseased lungs. Subsequent immunohistochemical analysis has
demonstrated overexpression of MMP-7 in the alveolar pneumocytes and
within the interstitium in specimens from patients with NSIP and IPF.
Additionally, intense staining for MMP-7 also was seen in areas
considered to be sites of active fibrosis, termed fibroblastic
foci, in patients with IPF. While additional confirmation is
necessary, these results support the hypothesis that
metalloproteinases, especially MMP-7, may have an important role in
fibrosing lung disorders.