In vitro inhibition of matrix metalloproteinase activity in tracheal epithelial lining fluid from horses with recurrent airway obstruction.

This research study investigates the effects of synthetic matrix metalloproteinase (MMP) inhibitors on certain activities in horses with recurrent airway obstruction. The study found that these inhibitors can potentially reduce the destructive inflammation associated with chronic lung disease.

Background

• The study intends to explore the role of synthetic MMP inhibitors on gelatinolytic and collagenolytic activities in horses suffering from recurrent airway obstruction (RAO).
• Matrix metalloproteinases (MMPs) are enzymes that are involved in the breakdown of extracellular matrix, a function that can prove harmful in certain diseases. For example, in chronic inflammatory diseases like RAO, the excess MMP activity results in the destruction of healthy lung tissue.

Methods

• The participants in this experiment were 10 horses diagnosed with RAO and 5 healthy horses as controls.
• The research methods used were substrate-based functional assays. Such assays were deployed to measure endogenous collagenolytic and gelatinolytic activities in the tracheal epithelial lining fluid (TELF) of both the RAO-affected horses and the healthy ones.
• The MMP activity in TELF was inhibited in vitro using chemically modified tetracyclines (CMTs; CMT-3 and CMT-8) and bisphosphonates (BPs; zoledronate and pamidronate).

Results

• The results of the study demonstrated that CMT-3, CMT-8, zoledronate, and pamidronate were capable of inhibiting TELF type I collagenolytic and gelatinolytic activities in a dose-dependent manner.
• However, complete inhibition of these activities was not seen with the tested inhibitor concentrations of 25 to 500 microM.
• Among the tested inhibitors, CMTs inhibited pathologically induced collagen I degradation more effectively than BPs. Notably, CMT-3 was identified as having the most effect on restricting gelatinolytic activity, and its efficiency was comparable to that of BPs.

Conclusions

• The researchers concluded that an increase in MMP activity related to chronic lung diseases, such as in the equine respiratory tract, could potentially be hindered by administering CMTs or BPs.
• This means that these synthetic MMP inhibitors may eventually serve as an additional form of pharmacologic treatment aimed at reducing the damaging inflammation associated with ongoing active tissue destruction in chronic lung conditions.
• The study also suggests that these MMP inhibitors, by targeting only excessive MMP activities, can limit the adverse side effects typically associated with more potent inhibitors.