Sputum levels of metalloproteinase-9 and tissue inhibitor of metalloproteinase-1, and their ratio correlate with airway obstruction in lung transplant recipients: relation to tumor necrosis factor-alpha and interleukin-10

J Heart Lung Transplant. 2001 Nov;20(11):1144-51. doi: 10.1016/s1053-2498(01)00325-4.


Background: Chronic transplant rejection is characterized by progressive narrowing of small airways caused by matrix remodeling and fibrosis. Matrix-metalloproteinases (MMPs) and their inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), are involved in the turnover of extracellular matrix.

Methods: To clarify the contribution of MMPs and TIMPs to airway inflammation in patients after lung transplantation (LTx), we used enzyme immunoassays to measure induced sputum concentrations of MMP-9, TIMP-1, and controlling cytokines tumor necrosis factor (TNF)-alpha and interleukin (IL)-10 of 30 LTx patients and 15 control subjects.

Results: Sputum concentrations of MMP-9, TIMP-1, the MMP-9:TIMP-1 ratio, and TNF-alpha were higher in LTx patients than in control subjects (p < 0.04, all comparisons). The MMP-9, MMP-9:TIMP-1, and TNF-alpha levels were also significantly higher in LTx patients with chronic rejection compared with those with stable organ function (p < 0.03, all comparisons), whereas IL-10 levels were higher in the latter group (p = 0.05). In all LTx patients, MMP-9 and the MMP-9:TIMP-1 ratio were negatively correlated with forced expiratory volume in 1 second values (rho = -0.47, p = 0.01, and rho = -0.53, p = 0.003, respectively). We found that MMP-9 positively correlated with sputum neutrophils and TNF-alpha whereas MMP-9 and TIMP-1 did not correlate with IL-10.

Conclusions: These data underline the possible contribution of proteases such as MMP-9 to chronic transplant rejection, and suggest that an imbalance of MMP-9 and TIMP-1 may be involved in the pathogenesis of airway obstruction after LTx. We found that MMP-mediated inflammation seems to be controlled by TNF-alpha whereas IL-10 might elicit anti-inflammatory effects through different pathways.

MeSH terms

  • Adolescent
  • Adult
  • Airway Obstruction / enzymology*
  • Airway Obstruction / etiology
  • Graft Rejection / enzymology
  • Humans
  • Immunoenzyme Techniques
  • Interleukin-10 / analysis*
  • Lung Transplantation*
  • Matrix Metalloproteinase 9 / analysis*
  • Middle Aged
  • Postoperative Complications
  • Sputum / chemistry*
  • Sputum / cytology
  • Tissue Inhibitor of Metalloproteinase-1 / analysis*
  • Tumor Necrosis Factor-alpha / analysis*


  • Tissue Inhibitor of Metalloproteinase-1
  • Tumor Necrosis Factor-alpha
  • Interleukin-10
  • Matrix Metalloproteinase 9