The Expression of HoxB5 and its Role in Neonatal Rats with Chronic Lung Disease

The purpose of this investigation is to research the expression and effect of HoxB5 during pulmonary injury and to investigate the repairing ability of alveolar epithelial cells in such processes. Eighty neonatal rats were randomly divided into two groups: a group of high concentration of oxygen and the control group. The high oxygen group would inhale 85 to 90% oxygen and the control group would inhale air. The lung tissues on the 1st, 3rd, 7th, 14th, and 21st days would be obtained, in which immunohistochemical assay and Reverse Transcription Polymerase Chain Reaction (RT-PCR) would be performed to test the expressions of proteins and mRNAs of surfactant protein C (SPC) and AQP5. For expression of HoxB5 protein and its mRNA, immunohistochemical assay, western blot, in-situ hybridization, and RT-PCR would be run. The expression of SPC in the group of high concentration of oxygen was significantly reduced on day 3. Its expressions on day 14 and day 21 were significantly higher than those of the control group (p < 0.05). The expression ofAQP5 in the group of high concentration of oxygen progressively decreased and such difference with the control group was significant (p < 0.05). The four experimental methods all showed the expression of HoxB5 in the group with high concentration of oxygen gradually decreased since day 7 (p < 0.05). High concentration of oxygen is damaging to alveolar epithelial cells. Although the number of type II alveolar epithelial cells (AECII) increases, its ability to differentiate and transform is significantly reduced and the reduced expression level of HoxB5 is possibly the reason for AECII to lose differentiation function to AECI.