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Matrix metalloproteinases and TIMP-1 production by peripheral blood granulocytes from COPD patients and asthmatics
Abstract:
Both asthmatic and COPD patients were found to have increased amounts of granulocytes and matrix metalloproteinase-9 (MMP-9) in their sputum. The present study was conducted to investigate whether the elevated amounts of MMP-9 and TIMP-1 found in such patients' airways may be linked to an enhanced secretion by granulocytes. Blood granulocytes from asthmatics (n = 10), COPD patients (n = 11), and healthy controls (n = 11) were isolated and cultured under basal conditions or after stimulation by phorbol 12-myristate 13-acetate (PMA) or N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP). MMP-9 activity was detected by zymography while MMP-8 and TIMP-1 levels were measured by ELISA. In zymography, pro- and activated forms of MMP-9 were present in each group (healthy subjects, asthmatics, and COPD patients). Spontaneous release was not different between the three groups. Stimulation by fMLP and PMA increased to a similar extent the release of MMP-9 by granulocytes in all the three groups. TIMP-1 levels were also increased after stimulation by PMA and fMLP only in healthy subjects and COPD patients. MMP-8 levels were barely detectable. We conclude that circulating granulocytes from COPD patients and asthmatics do not display an abnormal secretion of MMP-9, and that granulocytes from asthmatics have an impaired ability to release TIMP-1 upon stimulation.
Insights
Granulocytes from asthma and COPD patients do not show abnormal matrix metalloproteinase-9 (MMP-9) secretion. However, asthmatic granulocytes exhibit impaired release of tissue inhibitor of metalloproteinase-1 (TIMP-1) upon stimulation.
Area of Science:
- Respiratory Medicine
- Immunology
- Biochemistry
Background:
- Increased granulocytes and matrix metalloproteinase-9 (MMP-9) are observed in asthma and COPD airways.
- The role of granulocyte secretion in elevated MMP-9 and TIMP-1 levels in these conditions requires investigation.
Purpose of the Study:
- To investigate if granulocytes from asthma and COPD patients exhibit altered secretion of MMP-9 and TIMP-1.
- To compare MMP-9 and TIMP-1 secretion in granulocytes from healthy individuals, asthmatics, and COPD patients.
Main Methods:
- Isolated blood granulocytes from healthy subjects, asthmatics, and COPD patients.
- Cultured granulocytes under basal conditions and stimulated with PMA or fMLP.
- Assessed MMP-9 activity via zymography and MMP-8 and TIMP-1 levels using ELISA.
Main Results:
- MMP-9 (pro- and activated forms) was present in all groups.
- Granulocyte stimulation with fMLP and PMA similarly increased MMP-9 release across all groups.
- TIMP-1 levels increased post-stimulation in healthy subjects and COPD patients, but not significantly in asthmatics.
Conclusions:
- Circulating granulocytes in COPD and asthmatic patients do not show abnormal MMP-9 secretion.
- Granulocytes from asthmatic patients demonstrate an impaired capacity for TIMP-1 release upon stimulation.