Correlation Between Proteolytic Enzymes and Microangiogenesis in Degenerative Intervertebral Disc Nucleus

Goal of the review?

The goal of the article, ¹ explores the molecular level of intervertebral disc degeneration. Specifically, the authors examine the correlation between proteolytic enzymes, microvascular formation, or neve fibre ingrowth in the intervertebral disc nucleus. 

 

Why are they doing this review?

To aid in diagnosis and treatment, the authors argue that it is important to understand the molecular level of disc degeneration and the functional changes that accompany degenerative IVD. By measuring the extracellular matrix components, such as collagen in the disc nucleus tissue, the relationship between the degrees of degeneration of the intervertebral disc (IVD) is analyzed. 

 

 

What was done?

They selected 40 patients for the case group, all of whom had degenerative disc nucleus pulposus (NP) and were admitted to the hospital. The inclusion criteria for this group were the presence of lumbar degenerative disease and cervical spondylosis. Additionally, they selected 20 healthy subjects for the control group, with inclusion criteria of cervical vertebra and lumbar vertebra injury caused by trauma. There was no significant difference in demographic characteristics, including age, gender, and other variables. 

The researchers took blood and NP tissue from each participant and stored the samples at 80º. They then carried out H&E staining and immunohistochemical staining to observe cathepsins such as aminopeptidase and vascular endothelial positive cells. Finally, they used statistical software to determine correlations.

 

What did they find?

In the normal group, the researchers found that following H&E staining, chondrocytes were clustered in the cartilage depression, and matrix staining was more uniform. In contrast, the chondrocytes were reduced for the case group, and the nucleus was stained or disappeared. When looking at immunohistochemical staining results, the normal group had little or no expression of aminopeptidase N (APN) and leucine aminopeptidase (LAP). However, in the patient group, APN and LAP were expressed in the degenerative IVD. These are important findings as a positive correlation between APN and LAP and degenerative changes to the IVD. Research shows that degenerative changes in the IVD tissue are associated with neovascularization. The appearance of proteolytic enzymes such as APN in the IVD and the relationship between microvessel formation and nerve in growth in the IV illustrate changes at the molecular level of disc degeneration. Moreover, the NP tissue was immunohistochemically stained with CD31-labeled VEGF, and the endothelial cells were stained singly or in clusters.

 

Why do these findings matter?

Understanding molecular changes to the IVD will help to diagnose better and treat issues related to degenerative IVD.