AIM: To examine the expression of matrix metallo-proteinase-1 (MMP-1) and tumor necrosis factor-α (TNF-α) in the colon mucosa of patients with ulcerative colitis (UC). METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry were used to examine the expression of MMP-1 and TNF-α at both mRNA and protein levels in the colon mucosa of patients with UC. Correlation between MMP-1 and TNF-α and their correlation with the severity of the disease were also analyzed statistically. RESULTS: The expression of MMP-1 and TNF-α in the ulcerated and inflamed colon mucosa of patients with UC was significantly higher than that in the non-inflamed mucosa of normal controls at both mRNA and protein levels. Furthermore, the expression of MMP-1 and TNF-α in the ulcerated area was significantly higher than that in the inflamed area of patients with UC (0.9797 ± 0.1433 vs 0.6746 ± 0.0373, 0.8669 ± 0.0746 vs 0.5227 ± 0.0435, P < 0.05). There was no statistically significant difference in the non-inflamed area of normal controls. There was a significant correlation between MMP-1 and TNF-α expression (0.9797 ± 0.1433 vs 0.8669 ± 0.0746, P < 0.05), the correlating factor was 0.877. MMP-1 and TNF-α showed a significant correlation with the severity of the disease (0.0915 ± 0.0044 vs 0.0749 ± 0.0032 , 0.0932 ± 0.0019 vs 0.0724 ± 0.0043, P < 0.05), their correlating factors were 0.942 and 0.890, respectively. CONCLUSION: Excessively expressed MMP-1 directly damages the colon mucosa by degrading extracellular matrix (ECM) in patients with UC. While damaging colon mucosa, excessively expressed TNF-α stimulates MMPs secreting cells to produce more MMP-1 and aggravates the mucosa damage. MMP-1 promotes secretion ofTNF-α in a positive feedback manner to cause further injury in the colon mucosa. MMP-1 and TNF-α correlate well with the severity of the disease, and therefore, can be used clinically as biological markers to judge the severity of UC. AIM: To examine the expression of matrix metallo-proteinase-1 (MMP-1) and tumor necrosis factor-α (TNF-α) in the colon mucosa of patients with ulcerative colitis (UC). METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry were used to examine the expression of MMP-1 and TNF-α at both mRNA and protein levels in the colon mucosa of patients with UC. Correlation between MMP-1 and TNF-α and their correlation with the severity of the disease were also statistically significant. RESULTS: The expression of MMP-1 and TNF-α in the ulcerated and inflamed colon mucosa of patients with UC was significantly higher than that in the non-inflamed mucosa of normal controls at both mRNA and protein levels. Furthermore, the expression of MMP-1 and TNF-α in the ulcerated area was significantly higher than that in the inflamed area of ​​patients with UC (0.9797 ± 0.1433 vs 0.6746 ± 0.0373, 0.8669 ± 0.0746 vs 0.5227 ± 0.0435, P <0.05). There was no statistically si There was a significant correlation between MMP-1 and TNF-α expression (0.9797 ± 0.1433 vs 0.8669 ± 0.0746, P <0.05), the correlating factor was 0.877. TNF-α showed a significant correlation with the severity of the disease (0.0915 ± 0.0044 vs. 0.0749 ± 0.0032, 0.0932 ± 0.0019 vs. 0.0724 ± 0.0043, P <0.05). CONCLUSION: Excessively expressed MMP -1 directly damages the colon mucosa by degrading extracellular matrix (ECM) in patients with UC. While damaging colon mucosa, excessively expressed TNF-α stimulates MMPs secreting cells to produce more MMP-1 and aggravates the mucosa damage. MMP-1 promotes secretion of TNF- [alpha] in a positive feedback manner to cause further injury in the colon mucosa. MMP-1 and TNF- [alpha] correlate well with the severity of the disease, and therefore, can be used clinically as biological markers to judge the severity of UC.