Fig 2: Comparison of sTREM2, MMP9, and CD44 levels in serum and CSF between anti-NMDAR encephalitis patients and controls. A, B The CSF sTREM2 levels were significantly increased (p < 0.001) in the anti-NMDAR encephalitis group, and the serum sTREM2 levels also showed an increasing trend (p = 0.003) compared with the controls. C The serum MMP9 levels were higher (p = 0.016) in the anti-NMDAR encephalitis group than in the controls. D, E CD44 levels in both the serum (D, p = 0.003) and the CSF (E, p = 0.18) were significantly higher in the anti-NMDAR encephalitis group than in the control group. Differences in CSF sTREM2 levels, serum sTREM2 levels, serum MMP9 levels, and CSF CD44 levels were assessed by the Mann‒Whitney test between the anti-NMDAR encephalitis group and the control group. Differences in serum CD44 levels were assessed by the independent two-sample t test. The above statistical results have been adjusted for age and sex

Fig 3: Correlation analysis of sTRME2 levels in CSF or serum with other parameters. A–C The CSF sTREM2 level was positively related to the serum sTREM2 level (r = 0.426, p = 0.021), the CSF CD44 level (r = 0.702, p < 0.0001), and the serum MMP9 level (r = 0.428, p = 0.021). D–F The CSF sTRME2 level was positively related to the mRS scale (r = 0.422, p = 0.023) and age (r = 0.407, p = 0.028) but negatively related to the GCS score (r = − 0.401, p = 0.031). Spearman correlation coefficients were used for the analysis

Fig 4: The predictive value of CSF sTREM2 and CSF CD44 for anti-NMDAR encephalitis. A, B Each patient’s clinical outcome was classified as good or poor according to the mRS score (mRS > 3 poor outcome, mRS ≤ 3 good outcome). In anti-NMDAR encephalitis, both CSF sTREM2 (p = 0.010) and CSF CD44 (p = 0.011) showed higher concentrations in patients with poor outcomes than in patients with good outcomes. C Receiver operating characteristic curve (ROC) analysis for CSF sTREM2 (AUC = 0.800, p = 0.009) and CSF CD44 (AUC = 0.794, p = 0.0125) in distinguishing good and poor clinical outcomes in anti-NMDAR encephalitis. D Receiver operating characteristic curve (ROC) analysis was applied to determine the diagnostic value of sTREM2 (CSF sTREM2 AUC = 0.864, p < 0.0001; serum sTREM2 AUC = 0.568, p = 0.4651), CD44 (CSF CD44 AUC = 0.729, p < 0.018; serum CD44 AUC = 0.837, p = 0.0003), and MMP9 (serum MM9 AUC = 0.687, p = 0.0436) in anti-NMDAR encephalitis. The Mann‒Whitney U test was applied when comparing the differences in CSF sTREM2 and CSF CD44 between the good outcome group and poor outcome group in anti-NMDAR encephalitis

Fig 5: The correlation between plasma HA, CD44 and RHAMM levels and DKD. Spearman correlation analysis was performed to evaluate the correlation between plasma HA, CD44 and RHAMM levels and DKD.