Activation of Bcl-2-Caspase-9 Apoptosis Pathway in the Testis of Asthmatic Mice

BACKGROUND Apoptosis plays a critical role in controlling the proliferation and differentiation of germ cells during spermatogenesis. Dysregulation of the fine-tuned balance may lead to the onset of testicular diseases. In this study, we investigated the activation status of apoptosis pathways in the testicular tissues under the background of an asthmatic mouse model. METHODS Ten BALB/c mice were divided into two groups: the acute asthma group and the control group. In the acute asthma group, ovalbumin (OVA)-sensitized mice were challenged with aerosolized OVA for 7 days, while the control group was treated with physiological saline. After that, both epididymis and testis were collected to determine the sperm count and motility. Apoptosis in the testis was evaluated by DNA ladder, immunochemistry and further by PCR array of apoptosis-related genes. Finally, the cleavage of caspase-3 and poly ADP-ribose polymerase (PARP) was determined by western blot and the enzymatic activities of caspase-9 and 3/7 were assessed using Caspase-Glo kits. RESULTS Compared with control mice, significant decreases in the body weight, testis weight, sperm count and motility were seen in the experimental group. DNA ladder and immunochemistry showed significant increase in apoptotic index of the asthmatic testis, whereas a decrease in mRNA expression of Bcl-2 and increases in Bax, BNIP3, caspase-9, and AIF were observed in the asthma group. Furthermore, protein levels of AIF were significantly upregulated, while the translational expression of Bcl-2 was downregulated markedly. Consistently, caspase-9 activity in the testis of asthma mice was significantly higher than that of the control group. CONCLUSION Collectively, these results showed that Bcl-2-caspase-9 apoptosis pathway was clearly activated in the testis of asthmatic mice with the increased expression of apoptosis-related genes and proteins. To our knowledge, this is the first report demonstrating that asthma could lead to the activation of the mitochondrial apoptosis signaling pathway in the mouse testis.