NanoString miRNA profiling of peripheral blood sorted CD14+CD16- monocytes from amyotrophic lateral sclerosis, multiple sclerosis and healthy control subjects

We investigated the innate immune system in the SOD1 ALS model. We found that splenic Ly6CHi monocytes were activated and their progressive recruitment to the spinal cord, but not brain, correlated with neuronal loss. We found a decrease in resident microglia in the spinal cord with disease progression. Two months prior to disease onset, splenic Ly6CHi monocytes had an M1 signature which included increased CCR2. At one month prior to disease onset, microglia expressed increased CCL2 and other chemotaxis-associated molecules. Microglia derived from the spinal cord of SOD1 mice recruited Ly6C+ monocytes to the CNS. Treatment with anti-Ly6C mAb modulated the Ly6CHi monocyte cytokine profile, reduced monocyte recruitment to the spinal cord, diminished neuronal loss and extended survival. In humans with ALS, CD14+/CD16- monocytes (analogue of Ly6CHi monocytes) exhibited an ALS specific microRNA inflammatory signature similar to that observed in the SOD1 mouse providing a direct link between the animal model and the human disease. Thus, the SOD1-like profile of monocytes in ALS subjects may serve as a biomarker for disease stage or progression. Our results suggest that recruitment of inflammatory monocytes plays an important role in disease progression and that modulation of these cells is a potential therapeutic approach. This study used the NanoString nCounter hybridization system and nCounter miRNA expression assays to identify and quantitate miRNAs in blood CD14+CD16- monocytes from ALS, MS and HC subjects