Super-high-dose methylprednisolone does not improve efficacy or induce glucocorticoid resistance in experimental...

Area of Science:

• Neuroimmunology
• Pharmacology
• Molecular Biology

Background:

• Glucocorticoids (GCs) are widely used to treat inflammatory diseases like experimental allergic encephalomyelitis (EAE).
• Understanding the mechanisms of GC resistance is crucial for optimizing therapeutic strategies.
• Methylprednisolone (MP) is a potent GC, but its optimal dosage and potential to induce resistance remain areas of investigation.

Purpose of the Study:

• To determine if super-high doses (SHD) of MP enhance therapeutic efficacy or cause GC resistance in EAE.
• To investigate the molecular mechanisms underlying potential GC resistance, focusing on glucocorticoid receptor (GR) isoforms and splicing factors.

Main Methods:

• Therapeutic effects of SHD and low-dose MP were assessed in EAE models by evaluating clinical scores, pathology, and cytokine levels.
• Immunohistochemistry and RT-PCR were employed to analyze the expression of GRα, GRβ isoforms, and the splicing factor SRp30c.

Main Results:

• Both SHD and low-dose MP demonstrated comparable therapeutic effects in EAE.
• A positive correlation was observed between the GRα/GRβ ratio and clinical score changes, indicating its association with GC sensitivity.
• No significant difference in the GRα/GRβ ratio was found between the SHD and low-dose MP groups.
• SRp30c mRNA levels were correlated with GRβ expression, suggesting its role in alternative splicing.

Conclusions:

• The GRα/GRβ ratio is a key indicator of GC sensitivity in EAE.
• SRp30c may be involved in the alternative splicing of GR pre-mRNA, leading to the generation of GRβ.
• SHD MP does not offer superior efficacy or induce GC resistance compared to low-dose MP in this EAE model.