Involvement of MT1‐MMP and TIMP‐2 in human periodontal disease

Oral Diseases (2010) 16 , 388–395 Objectives: Periodontal disease is characterized by an increased collagen metabolism. Although membrane type‐1 matrix metalloproteinase (MT1‐MMP) plays a critical role in collagen degradation, its involvement in human periodontitis remains to be determined. Methods: MT1‐MMP and TIMP‐2 expression and distribution were evaluated in gingival tissue samples derived from 10 healthy and 12 periodontitis‐affected human subjects. MT1‐MMP and TIMP‐2 expression were assessed through Western‐blot of tissue homogenates. The main cell types involved in MT1‐MMP and TIMP‐2 production were evaluated by means of immunohistochemistry. Results: Both MT1‐MMP and TIMP‐2 were significantly increased in periodontitis‐affected gingival tissues when compared to healthy gingiva. Moreover, the balance between MT1‐MMP and its inhibitor TIMP‐2 was altered in periodontitis‐affected tissues, suggesting an imbalance in this proteolytic axis. Immunohistochemistry demonstrated the expression of MT1‐MMP in fibroblasts and macrophages in gingival tissues. MT1‐MMP was detected in cells in close association with the gingival collagen matrix. TIMP‐2 expression was identified in fibroblasts, macrophages and epithelial cells. Conclusions: Our observations show an increased expression of MT1‐MMP and TIMP‐2 in periodontitis‐affected gingival tissues. The altered balance between these two molecular mediators of collagen remodeling suggests their involvement in human periodontal disease.     

The Influence of Micronutrient Trace Metals on Microcystis aeruginosa Growth and Toxin Production

Microcystis aeruginosa is a widespread cyanobacteria capable of producing hepatotoxic microcystins. Understanding the environmental factors that influence its growth and toxin production is essential to managing the negative effects on freshwater systems. Some micronutrients are important cofactors in cyanobacterial proteins and can influence cyanobacterial growth when availability is limited. However, micronutrient requirements are often species specific, and can be influenced by substitution between metals or by luxury uptake. In this study, M. aeruginosa was grown in modified growth media that individually excluded some micronutrients (cobalt, copper, iron, manganese, molybdenum) to assess the effect on growth, toxin production, cell morphology and iron accumulation. M. aeruginosa growth was limited when iron, cobalt and manganese were excluded from the growth media, whereas the exclusion of copper and molybdenum had no effect on growth. Intracellular microcystin-LR concentrations were variable and were at times elevated in treatments undergoing growth limitation by cobalt. Intracellular iron was notably higher in treatments grown in cobalt-deplete media compared to other treatments possibly due to inhibition or competition for transporters, or due to irons role in detoxifying reactive oxygen species (ROS).