The high molecular weight components of the MMP Pathway (HMW1 and HMW2) together with pro-MMP9 were clearly identifiable in the homogenates (Figure 2(a)).
In all donor samples, the HMW2 species existed in predominantly the bound state.
After a tenfold dilution of the homogenate, the levels of HMW2, HMW1, and pro-MMP2 were too low to be detected on the zymograms (Figure 3).
In control samples (donors 1 and 2), HMW1, HMW2, and pro-MMP9 species were present at the elution front (signifying the presence of the LMMC complex) but free MMPs were not detected in the later fractions implying that most of the MMP species present in the supernatant was bound within the LMMC complex.
AD samples (donors 7 and 9) showed little or no HMW1 and HMW2 in the LMMC region but the presence of considerable free levels of HMW1 and pro-MMP9.
These species were equivalent to the current designation from analysis of Bruch's membrane and other ocular tissues of pro-MMP2, pro-MMP9, HMW1, and HMW2, respectively .
As explained earlier, in AMD, the >3-fold increase in free pro-MMP9 increased the complexation with pro-MMP2 to form HMW2 (via the MMP Pathway) resulting in decreased levels of active-MMP2 .
High molecular weight gelatinase species of 130 and 280 kDa (corresponding to the current designation of HMW1 and HMW2, resp.) had previously been noted in brain tissue but the relevance of these findings to control of free MMP levels was not investigated [48, 49, 65].
The HMW2 species was virtually all bound in both control and AD brain samples.
In control brain supernatant samples, the content of HMW1 and HMW2 was associated with the LMMC complex with the virtual absence of free forms.
In control tissue (Figures 5 and 6) there is very little free HMW1, HMW2, or pro-MMP9 and it could be argued that these species may be aggregating with released cellular components to form the LMMC complex.
2.40 X 105 PP1 670,400 18,900 35.5 5.70 X 104 LMW 25,100 2280 11.0 2.99 X 101 HMW2
475,000 92,600 5.1 -- HMW3 686,000 87,000 7.9 -- Table 3 Determined Relaxation Spectra, Damping Functions, and Flow Activation Energies for Different Materials Used in This Work.