Macrophage polarisation to anti-inflammatory state in central nervous system after chondroitinase ABC treatment

Abstract

The microenvironment of the injured spinal cord activates macrophages to acquire pro-inflammatory M1 polarization with but transient and few acquiring anti-inflammatory M2 polarization. Given our observation of lowered numbers of pro-inflammatory macrophages/microglia following chondroitinase ABC (ChABC) treatment of the hemisected cord in a rat model, we hypothesized that chondroitin sulfate proteoglycans upregulated in the injured environment influences the balance between M1 and M2 polarization states. To test this, macrophages were derived from collections of bone marrow from adult rats and stimulated with lipopolysaccharide to trigger transition to the pro-inflammatory state. Following acute treatment of the cultures with ChABC versus vehicle control, RNA was recovered from the macrophage cultures for RT-PCR analysis of expression of polarization markers. Such M1 markers as inducible nitric oxide synthase and CD86 were found to be lowered in the ChABC-treated samples. In contrast, such M2 markers as arginase-1, CCL22 and IL10 were found to be higher. Experiments with the rat model revealed that ChABC treatment of the injured cord environment resulted in increased level of the IL10 transcript as compared to the vehicle control. The results so far support the hypothesis and add impetus to find strategies that shift the M1:M2 polarization as a therapeutic goal.