Progressive Multiple Sclerosis Transcriptome Deconvolution Indicates Increased M2 Macrophages in Inactive Lesions.

Accumulating evidence suggests M2 macrophages contribute to tissue reparation and limit inflammation in multiple sclerosis (MS). However, most studies have focused on murine models without substantial support through human MS observations. The present study aimed to quantify the relative abundances of M2 macrophages in different lesion types excised from human MS patients. CIBERSORTx, an established RNA deconvolution algorithm, was applied on bulk RNA-sequencing data developed from 98 lesions from 10 progressive MS patients and 5 neuropathological control donors. A validated gene signature matrix for 22 human hematopoietic cell subsets was used to infer the relative proportions of immune cells that were present in the original lesion. Deconvolution of the bulk gene expression data showed that inactive lesions contained significantly more M2 macrophages compared to normal white matter control samples. The findings suggest that M2 macrophages may play a role during lesion inactivity in MS.