MMP8 and pulmonary emphysema: In the present study, our analysis revealed an initial decrease in ECM fibers amount, which had occurred at times later than when we detected increases in polimorphonuclear leukocytes in parenchyma and in gene expression for collagenases MMP-8, -13 and for metalloelastase-12; only 21 days following emphysema induction we detected increases in some of the ECM fiber amounts in PPE groups.