Filter sterilization of highly infectious samples to prevent false negative analysis of matrix metalloproteinase...

Area of Science:

• Immunology
• Biochemistry
• Infectious Diseases

Background:

• Matrix metalloproteinases (MMPs) play a role in the immunopathology of infectious diseases.
• Analysis of MMPs in high-risk samples, such as those from Mycobacterium tuberculosis infection, often requires filter sterilization.

Purpose of the Study:

• To investigate the potential for commercial filter membranes to cause artifacts by binding MMPs during sample processing.
• To evaluate the impact of different filter types and pore sizes on MMP concentrations.

Main Methods:

• Filtration of samples containing MMP-1, MMP-7, and MMP-9 using various commercial membranes (Anopore, Polypropylene, Polysulphone, Durapore, Bio-inert) with different pore sizes (0.2 µM and 0.45 µM).
• Analysis of MMP concentrations and activity using zymography and Western blotting.

Main Results:

• Anopore 0.2 µM membrane filtration reduced MMP-1 concentrations to undetectable levels and removed all MMP-7 and MMP-9 activity.
• Polypropylene 0.45 µM filtration partially removed MMP-1.
• Polysulphone, Durapore, and Bio-inert 0.2 µM membranes did not significantly remove MMP-1.

Conclusions:

• Commercial filter membranes, particularly Anopore, can bind and remove MMPs from samples.
• The conserved MMP catalytic domain likely binds to the filter membrane.
• Careful selection of filter membranes is crucial to avoid artifacts and accurately assess MMP involvement in infectious disease immunopathology.