Vitamin D levels in systemic sclerosis patients: a meta-analysis.

PURPOSE: This study aimed to investigate the association between vitamin D and systemic sclerosis (SSc) by meta-analysis. METHODS: A comprehensive search was performed through June 12, 2017. Pooled standardized mean difference (SMD) was used to estimate the mean vitamin D difference between case and control groups (or between diffused- and limited-type SSc). Pooled risk ratios (RRs) with 95% confidence intervals (CIs) were used to assess the impact of vitamin D level on clinical characteristics of SSc patients. All statistical analyses were performed using Revman 5.0 software. RESULTS: The search yielded six studies with a total of 554 SSc patients and 321 healthy controls. The meta-analysis showed that SSc patients suffered from decreased vitamin D levels (SMD =-8.72 ng/mL; 95% CI: -10.11 to -7.32) compared with healthy controls. The meta-analysis results of three studies with 240 SSc patients (93 diffused-type and 147 limited-type SSc patients) showed that diffused-type SSc patients exhibited lower vitamin D levels (SMD =-4.71 ng/mL; 95% CI: -8.98 to -0.44) compared with limited-type SSc patients. However, vitamin D level was not found to be associated with Rodnan score (SMD =-2.29 ng/mL, 95% CI: -8.49 to 3.91, P=0.47), systolic pulmonary pressure (SMD =-1.68 ng/mL, 95% CI: -10.79 to 7.43, P=0.72), gastrointestinal ulcer (RR =1.01, 95% CI: 0.53-1.93, P=0.98), or pulmonary involvement (RR =1.01, 95% CI: 0.36-2.86, P=0.99) in SSc patients. CONCLUSION: SSc patients exhibited lower vitamin D levels compared with healthy controls. Vitamin D levels in diffused-type SSc patients were significantly lower than those in limited-type SSc patients. The severity of clinical features was not associated with the extent of vitamin D deficit. Therefore, we hypothesize that SSc patients, especially diffused type, have lower vitamin D levels, and that the decrease of vitamin D levels might not be an accelerating factor of SSc severity.

Glycyrrhizin improves p75NTR-associated sciatic nerve regeneration in a BALB/c mouse model.

Glycyrrhizin has a role in immune regulation in the central nervous system, but its impact on sciatic nerve injury had not previously been reported. In this study, a BALB/c mouse model of sciatic nerve injury was used to explore the role of glycyrrhizin in sciatic nerve repair and its underlying mechanism. Glycyrrhizin with intragastric gavage of 10 and 20 mg/kg weight per day (mid- and high-dose, respectively) inhibited p75 neurotrophin receptor (p75NTR) expression at the protein and mRNA levels versus the 5 mg/kg (low-dose) group and control (0.9% NaCl solution) at one, two, four and eight weeks following sciatic nerve injury, and simultaneously improved the action potential amplitude and motor nerve conductive velocity. Combined Marsland, Glees and Erikson's silver stain and Luxol fast blue staining results indicated that high- and mid-dose glycyrrhizin promoted improved sciatic nerve myelination compared with the low-dose or control groups eight weeks after injury. Immunofluorescence staining demonstrated that glycyrrhizin had an inhibitory effect to a certain degree on local hypertrophic scar and inflammatory responses in the mouse model. In conclusion, glycyrrhizin can promote sciatic nerve regeneration and functional repair, in which doses of 10 and 20 mg/kg per day are more effective than lower doses, and such regeneration is associated with the downregulation of p75NTR.