Expression analysis of BDNF, BACE1 and their antisense transcripts in inflammatory demyelinating polyradiculoneuropathy

Types and Concentrations of Blood-Based Biomarkers in Adults With Peripheral Neuropathies: A Systematic Review and Meta-analysis

Importance

Peripheral neuropathies are common conditions and can result in numbness, paresthesia, motor deficits, and pain. There is increasing evidence for the use of biomarkers as clinical indicators of the presence, severity, and prognosis of nerve lesions; however, biomarker identification has largely been focused on disorders of the central nervous system, and less is known about their role in the peripheral nervous system.

Objective

To assess blood-based biomarker concentrations associated with nerve involvement in patients with peripheral neuropathy compared with control participants.

Data Sources

Ovid, MEDLINE, Embase, and CINAHL were searched from inception to September 23, 2021.

Study Selection

Observational studies reporting on blood biomarkers in patients diagnosed with peripheral neuropathy were included. This review was preregistered on PROSPERO and followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline. Data were abstracted by 1 investigator and independently reviewed by a second.

Data Extraction and Synthesis

Data were meta-analyzed when at least 2 studies reported the same biomarker with comparable methodology. Fixed-effects models were used when only 2 studies were included; random-effects models were used when more than 2 studies were included.

Main Outcomes and Measures

The outcome of interest was concentration of biomarkers.

Results

This review included 36 studies reporting on 4414 participants, including 2113 control participants and 2301 patients with peripheral neuropathy with 13 distinct peripheral neuropathy diagnoses. Diabetic neuropathy was the most common neuropathy diagnosis (13 studies), followed by Charcot-Marie-Tooth disease (6 studies) and Guillain-Barre syndrome (6 studies). Overall, 16 different blood-based biomarkers associated with nerve involvement were evaluated. The most used were neurofilament light chain, S100B, brain-derived neurotrophic factor, and neuron-specific enolase. Patients with peripheral neuropathy demonstrated significantly higher levels of neurofilament light chain compared with controls (standardized mean difference [SMD], 0.93 [95% CI, 0.82 to 1.05]; P < .001). There were no significant differences in levels of S100B (SMD, 1.10 [95% CI, -3.08 to 5.28]; P = .38), brain-derived neurotrophic factor (SMD, -0.52 [95% CI, -2.23 to 1.19]; P = .40), or neuron-specific enolase (SMD, -0.00 [95% CI, -1.99 to 1.98]; P = .10) in patients with peripheral neuropathy compared with control participants.

Conclusions and Relevance

The findings of this systematic review and meta-analysis support the use of neurofilament light chain as a blood-based measure associated with the presence of neuronal injury in patients with peripheral neuropathy.

Dysregulation of lncRNAs in autoimmune neuropathies

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and Guillain-Barré syndrome (GBS) are inflammatory neuropathies with different clinical courses but similar underlying mechanisms. Long non-coding RNAs (lncRNAs) might affect pathogenesis of these conditions. In the current project, we have selected HULC, PVT1, MEG3, SPRY4-IT1, LINC-ROR and DSCAM-AS1 lncRNAs to appraise their transcript levels in the circulation of CIDP and GBS cases versus controls. Expression of HULC was higher in CIDP patients compared with healthy persons (Ratio of mean expression (RME) = 7.62, SE = 0.72, P < 0.001). While expression of this lncRNA was not different between female CIDP cases and female controls, its expression was higher in male CIDP cases compared with male controls (RME = 13.50, SE = 0.98, P < 0.001). Similarly, expression of HULC was higher in total GBS cases compared with healthy persons (RME = 4.57, SE = 0.65, P < 0.001) and in male cases compared with male controls (RME = 5.48, SE = 0.82, P < 0.001). Similar pattern of expression was detected between total cases and total controls. PVT1 was up-regulated in CIDP cases compared with controls (RME = 3.04, SE = 0.51, P < 0.001) and in both male and female CIDP cases compared with sex-matched controls. Similarly, PVT1 was up-regulated in GBS cases compared with controls (RME = 2.99, SE = 0.55, P vale < 0.001) and in total patients compared with total controls (RME = 3.02, SE = 0.43, P < 0.001). Expression levels of DSCAM-AS1 and SPRY4-IT1 were higher in CIDP and GBS cases compared with healthy subjects and in both sexes compared with gender-matched healthy persons. Although LINC-ROR was up-regulated in total CIDP and total GBS cases compared with controls, in sex-based comparisons, it was only up-regulated in male CIDP cases compared with male controls (RME = 3.06, P = 0.03). Finally, expression of MEG3 was up-regulated in all subgroups of patients versus controls except for male GBS controls. SPRY4-IT could differentiate CIDP cases from controls with AUC = 0.84, sensitivity = 0.63 and specificity = 0.97. AUC values of DSCAM-AS1, MEG3, HULC, PVT1 and LINC-ROR were 0.80, 0.75, 0.74, 0.73 and 0.72, respectively. In differentiation between GBS cases and controls, SPRY4-IT and DSCAM-AS1 has the AUC value of 0.8. None of lncRNAs could appropriately differentiate between CIDP and GBS cases. Combination of all lncRNAs could not significantly enhance the diagnostic power. Taken together, these lncRNAs might be involved in the development of CIDP or GBS.

Abnormal gene expression of BDNF, but not BDNF-AS, in iPSC, neural stem cells and postmortem brain samples from bipolar disorder

BACKGROUND

Brain-derived neurotrophic factor (BDNF) antisense RNA (BDNF-AS) was identified as naturally conserved non-coding antisense RNA that suppresses the transcription of BDNF.

METHODS

We measured the expression of BDNF mRNA and BDNF-AS mRNA in iPSC and NSC from bipolar disorder (BD) patients and healthy control subjects, and postmortem brain samples such as the corpus callosum, the Brodmann area (BA8), and BA46 from BD patients and age- and sex-matched controls.

RESULTS

The expression of BDNF mRNA in iPSC from BD patients (n = 6) was significantly lower than that of control subjects (n = 4) although the expression of BDNF mRNA in NSC from BD patients was significantly higher than that of control subjects. In contrast, there were no changes in the expression of BDNF-AS mRNA in both iPSC and NSC between two groups. The expression of BDNF mRNA in the BA46 from BD patients (n = 35) was significantly lower than that of controls (n = 34) although the expression of BDNF mRNA in the corpus callosum and BA8 was not different between two groups (n = 15). In contrast, there were no changes in expression of BDNF-AS mRNA in the three brain regions between two groups. Interestingly, there were significant positive correlations between BDNF mRNA expression and BDNF-AS mRNA expression in the postmortem brain samples.

LIMITATIONS

Sample sizes are relatively low.

CONCLUSIONS

Our data suggest that abnormalities in the expression of BDNF, but not BDNF-AS, play a role in the pathogenesis of BD.