TGF-β1 related inflammation in the posterior longitudinal ligament of cervical spondylotic myelopathy patients.

Aim: This study aimed to elucidate the pathogenesis of posterior longitudinal ligament (PLL) hypertrophy.

Methods: Cervical PLL specimens were collected from CSM patients during surgery (n = 30) and during routine autopsy (n = 14), and processed for histological examination (HE staining and Masson's Trichrome staining) and IHC (CD3, CD68, CD31, TGF-β1 and collagen II). In addition, the mRNA expression of collagen I was detected in cervical PLL specimens from 16 CSM patients (n = 16) and from routine autopsy (n = 16) by RT-PCR.

Results: Obvious fibrosis, cartilage metaplasia and calcification were found in the cervical PLL of CSM patients. In the degenerated PLL, CD68(+) macrophages were frequently identified, CD3(+) T lymphocytes were occasionally found, and many newly generated small vessels were also present. In the degenerated PLL, of the number of TGF-β1 positive cells increased markedly when compared with control group. IHC indicated TGF-β1 was secreted by macrophages. RT-PCR showed a significantly lower mRNA expression of collagen I in the PLL of CSM patients as compared to control group.

Conclusions: Macrophages are the major type of inflammatory cells involved in the cervical PLL degeneration, and TGF-β1 is related to the cervical PLL degeneration. TGF-β1 is mainly secreted by macrophages. Anti-inflammation may serve as an alternative non-surgical treatment and prophylactic strategy for PLL degeneration.