The Expression Of AQP1and AQP3in The Endplates And Annulus Fibrosus Of Human Intervertebral Disc

[Objective] Comparing the expression level of Aquaporin1(AQP1) and Aquaporin3(AQP3) in the cartilage endplate and annulus fibrosus of human intervertebral disc (IVD), to analyze the relationship between disc degeneration of different degenerative degree and expression level of AQPs, to provide new ideas for pathophysiological mechanisms of disc degeneration.[Methods]1. All45cases including idiopathic scoliosis children’s disc and discs in patients of intervertebral disc degeneration disease assessed by the grade of Pfirrmann’s way. HE staining and real-time quantitative PCR of type II collagen mRNA were taken to assess the degree of disc degeneration.2. Immunohistochemical techniques was used to determine the expression of AQP1and AQP3in the cartilage endplate and annulus fibrosus, and measured the rate of immunopositive cells.3. Quantitative real-time PCR was implyed to determine the mRNA expression level of AQP1and AQP3in the cartilage endplates and annulus fibrosus.4. The statistical software SPSS17.0was used to analyze the data.[Results]1. HE staining results:(1) The control group:the normal cartilage endplate matrix was stained in red unifirmly, the number of chondrocytes is higher, and so was cartilage lacuna.the annular fibrosus arranged distinctly.(2) The degenerative group:the number of chondrocytes decreased, and so was cartilage lacuna. The chondrocytes shrinkaged and its intercellular substance was lightly stained and became fibrosis. The annular fibrosus were distorted and in structural disorder, the number of annulus fibrosus cell decreased.2. Immunohistochemistry results:AQP1and AQP3were positive in the cartilage endplate and annulus fibrosus of the control group and the degenerative group. AQP1was mainly expressed in the cytoplasm, AQP3also was visible in the cell membrane but weak, and no expression in the nucleus. The rate of AQP1and AQP3immunopositive cells decreased as the aggravated degeneration degree of IVD. There was no significant difference between I and II group, but the difference between high-grade degenerative group (IV, V) and low-grade degenerative group (I-III) was significant (P<0.05).3. Quantitative real time PCR results collagen type II:AQP1, AQP3and were expressed in the human Cartilage endplate and annulus fibrosus.The mRNA relative expression of collagen type II decreased as the aggravated degeneration degree of IVD. In the Cartilage endplate:there was no significant difference among group I, II and III, but the difference was significant between high-grade degenerative group (IV, V) and low-grade degenerative group (Ⅰ-Ⅲ)(P<0.05). The difference between group IVand V was significant (P<0.05). In the annulus fibrosus:the difference between between high-grade degenerative group (Ⅲ-Ⅴ) and low-grade degenerative group (Ⅰ,Ⅱ) was significant (P<0.05). The difference between between III and V was significant (P<0.05).The mRNA relative expression of AQP1and AQP3in the Cartilage endplate and annulus fibrosus decreased along with the aggravated degeneration degree of IVD. The mRNA relative expression of AQP1and AQP3in group I was similar to group Ⅱ, but higher level in group Vthan in group Ⅰ,ⅡI and Ⅲ (P<0.05). The relative expression of AQP3in group III was lower than that in group II (P<0.05), and so was group V and group III (P<0.05).[Conclusion]1. AQP1and AQP3were both expressed in cartilage endplate and annulus of human normal intervertebral disc and degenerative intervertebral disc.2. The expression level of AQP1and AQP3in control group is much higher than the one in the degenerative group.3. The decrease of AQP1and AQP3expression level were obvious when the disc degenerated hard.