Matrix metalloproteinase pattern in celiac duodenal mucosa

Matrix metalloproteinases (MMPs) are a family of endopeptidases playing a key role in tissue remodelling in both physiological and pathological conditions. Since little information is available about their role in celiac disease (CD), our aims were to quantify their expression/activity and to investigate their relation to proinflammatory cytokines in this condition. Duodenal biopsies from untreated, treated celiac patients and controls were used to quantify the expression of MMP-1, MMP-2, MMP-3, MMP-9, MMP-12, MMP-14, their inhibitor TIMP-1, IFN-c and TNF-a by using real-time reverse transcription-polymerase chain reaction and the gelatin/casein/elastin activities by gel zymography, and to isolate lamina propria mononuclear cells (LPMCs). These cells and myofibroblasts isolated from jejunal specimens were incubated in the absence or presence of IFN-c and TNF-a. MMP-1 and MMP-12 mRNA levels were significantly increased in active CD compared to treated (Po0.01 and Po0.0005, respectively) and normal mucosa (Po0.01 and Po0.0005, respectively), and this was paralleled by an upregulation of caseinolytic and elastolytic activities. Furthermore, MMP-12 levels significantly (Po0.05) correlated with those of IFN-c and the degree of villous flattening. MMP-2 turned out to be significantly (Po0.05) reduced in untreated and treated celiacs compared to controls. In active CD, transcripts of TIMP-1 were higher than in treated and controls (Po0.005 and Po0.05, respectively), such as those of IFN-c (Po0.05), whereas TNF-a levels were suppressed (P¼0.0001). In physiological condition, myofibroblasts represent the main source of MMP-2, whereas LPMCs produce almost all MMPs only after cytokine stimulation. Conversely, cells isolated from active patients constitutively express MMPs without any increase after cytokine stimulation, while those from treated patients are in a resting condition. In conclusion, our results show the presence of a peculiar MMP pattern in active CD strongly dominated by MMP-12, correlating either with IFN-c or the degree of mucosal damage.