Hydrogen sulfide is expressed in the human and the rat cultured nucleus pulposus cells and suppresses apoptosis induced by hypoxia

Apoptosis plays pivotal role in the pathogenesis of degenerative disc diseases, which is the primary contributor to low back pain. Although the role of hydrogen sulfide (H2S) in cell apoptosis is well appreciated, the effects and mechanism that H2S regulates the program death of intervertebral disc cell are not yet elucidated. In this study, we utilized the nucleus pulposus (NP) from patients with lumbar disc herniation to investigate the relationship between endogenous H2S and NP cells apoptosis in human. Furthermore, we analyzed primary rat NP cells to study the effects of exogenous H2S on hypoxia induced cell apoptosis. Human NP samples were obtained from patients with lumbar disc herniation and were divided into uncontained and contained herniation groups. Using immunohistochemistry staining and sulphur-sensitive electrode, we detected the expression of cystathionine-β-synthase (CBS) and cystathionine γ-lyase (CSE), as well as the production of endogenous H2S in human NP. Tunel staining showed increased apoptosis in NP from herniated disc; and there was significant correlation between H2S generation and apoptosis in human NP. CoCl2 was then used to induce hypoxia in cultured primary rat NP cells. Annexin V staining indicated that exogenous NaHS attenuated hypoxia induced apoptosis in rat NP cells. Furthermore, hypoxia significantly increased the levels of multiple apoptosis associated proteins (Fas, Cytochromes C, Caspase 9 and cleaved-Caspase-3) in cells, which were eliminated by NaHS. Our study demonstrates the presence of endogenous H2S in human intervertebral disc; and the endogenous H2S generation rate is associated with NP apoptosis in herniated disc. In vitro study showes exogenous H2S donor attenuates hypoxia induced apoptosis in primary rat NP cells. Thus, our work provides insights that H2S may have beneficial effects in treating degenerative disc diseases.