Oral treatment with glycyrrhizin inhibits NLRP3 inflammasome activation and promotes microglial M2 polarization after traumatic spinal cord injury.

The inflammatory response induced by traumatic spinal cord injury (SCI) involves the activation of NLRP3 inflammasomes, which are closely related to the activation of microglia. Microglial polarization between M1/M2 phenotypes is a pivotal regulatory factor in neuroinflammatory responses to traumatic SCI-induced secondary injuries, and altering this polarization could be beneficial. Glycyrrhizin is a neuroprotective agent with a potent anti-inflammatory property in different neurological disorders and could potentially be useful in SCI. In this study, we investigated the potency of oral treatment with glycyrrhizin to reduce inflammation and improve functional recovery after traumatic SCI by inhibiting NLRP3 inflammasome activation and promoting microglial M2 polarization. After inducing traumatic SCI by dropping a 10 g impactor on the T9 and T10 spinal segments of male Sprague-Dawley rats, the animals were given glycyrrhizin orally immediately after injury and every 12 h for the next 3 d. Behavioral scores improved in glycyrrhizin-treated animals compared to the SCI group. The functional improvement in glycyrrhizin-treated rats paralleled the decreased expression of NLRP3 inflammasome components, such as ASC, NLRP3, and cleaved caspase-1, as well as IL-1ß and IL-18. At the histopathological level, oral treatment with glycyrrhizin diminished the SCI-enhanced production of Iba-1+CD86+ cells (M1 microglia) but improved the release of Iba-1+CD206+ cells (M2 microglia). Likewise, oral therapy with glycyrrhizin significantly enriched the protein expression levels of M2 microglia-related markers (CD206 and Arg-1) but reduced those of M1 microglia-related markers (CD86 and iNOS) in the injured spinal cord. These findings support and extend the knowledge on post-traumatic SCI glycyrrhizin-mediated neuroprotection. Glycyrrhizin's regulation of NLRP3 inflammasome activation and microglial polarization might be a new approach to understanding the anti-inflammatory potency of glycyrrhizin.

A comparative study on screw loosening in osteoporotic lumbar spine fusion between expandable and conventional pedicle screws.

INTRODUCTION: The aim of this study is to compare the rate of screw loosening and clinical outcomes of expandable pedicle screws (EPS) with those of conventional pedicle screws (CPS) in patients treated for spinal stenosis (SS) combined with osteoporosis. METHODS: One hundred and fifty-seven consecutive patients with SS received either EPS fixation (n = 80) or CPS fixation (n = 77) to obtain lumbosacral stabilization. Patients were observed for a minimum of 24 months. Outcome measures included screw loosening, fusion rate, Japanese Orthopaedic Association (JOA) scores and Oswestry disability index (ODI) scoring system, and complications. RESULTS: In the EPS group, 20 screws became loose (4.1%) in 6 patients (7.5%), and two screws (0.4%) had broken. In the CPS group, 48 screws became loose (12.9%) in 15 patients (19.5%), but no screws were broken. The fusion rate in the EPS group (92.5%) was significantly higher than that of the CPS group (80.5%). The rate of screw loosening in the EPS group (4.1%) was significantly lower than that of the CPS group (12.9%). Six EPS (1.8%) screws were removed. In the EPS group, two screws had broken but without neural complications. Twelve months after surgeries, JOA and ODI scores in the EPS group were significantly improved. There were four cases of dural tears, which healed after corresponding treatment. CONCLUSIONS: EPS can decrease the risk of screw loosening and achieve better fixation strength and clinical results in osteoporotic lumbar spine fusion.