Molecular Examination of Differentially Expressed Genes in the Brains of Experimental Autoimmune Encephalomyelitis Mice Post Herceptin Treatment

Abstract

Objective: Herceptin (trastuzumab) is an approved drug for treating HER2+ breast cancer patients, but its use for other diseases is not established. We sought to investigate the effects of Herceptin on ameliorating experimental autoimmune encephalomyelitis (EAE) and to examine its effects on the expression of various genes.

Methods: We used in-silico analysis of publicly available data, qRT-PCR, and immunohistochemistry (IHC) to determine the expression of HER2+ cells in the brains of EAE mice. IHC was also utilized to determine the anti-inflammatory effects of Herceptin. The ability of Herceptin to alleviate the EAE clinical score was measured in these mice. Bioinformatics analysis of publicly available data and qRT-PCR were performed to investigate the differentially expressed genes that were either up-regulated or down-regulated during the high clinical score (HCS) of the disease.

Results: We observed that HER2/Erbb2, the receptor for Herceptin is upregulated in the brains of EAE mice when the brains were examined at the HCS stage. Further, we demonstrated that Herceptin ameliorates the EAE disease, increasing re-myelination, reducing brain inflammation, CD3+ T cell accumulation, and HER2+ cells in the brains of these mice. Molecular analysis demonstrated the expression of different genes that were either up-regulated or down-regulated during the HCS of the disease. Our combined bioinformatics and qRT-PCR analyses show increased mRNA expression of Atp6v0d2, C3, C3ar1, Ccl3, Ccl6, Cd74, Clec7a, Cybb, H2-Aa, Hspb1, Lilr4b, Lilrb4a, Mpeg1, Ms4a4a, Ms4a6c, Saa3, Serpina3n and Timp1, at HCS. Except for the mRNA levels of Cd74 and Clec7a which were increased at HCS when Herceptin was used in both prophylactic and therapeutic regimens, the levels of other described mRNAs were reduced.

Conclusion: These novel findings show that Herceptin ameliorates the clinical score in EAE mice and are the first to investigate in detail the differential gene expression post-treatment with the drug.