Background
Chondroitin sulfate proteoglycans (CSPGs) are potent inhibitors of axonal regrowth and remyelination. More recently, they have also been highlighted as a modulator of macrophage infiltration into the central nervous system in experimental autoimmune encephalomyelitis, an inflammatory model of multiple sclerosis.
Conclusions
These results emphasize CSPGs as a prominent modulator of neuroinflammation and they highlight CSPGs accumulating in lesions in promoting axonal injury.
Methods
We interrogated
Results
The strongest evidence for genetic association was seen for SNPs mapping to the region containing the glycosyltransferase exostosin-like 2 (EXTL2), an enzyme that normally suppresses CSPG biosynthesis. Six of these SNPs showed genome-wide significant evidence for association in one of the studies with concordant and nominally significant effects in the second study. We then went on to show that a demyelinating injury to the spinal cord of EXTL2-/- mice resulted in excessive deposition of CSPGs in the lesion area. EXTL2-/- mice had exacerbated axonal damage and myelin disruption relative to wild-type mice, and increased representation of microglia/macrophages within lesions. In tissue culture, activated bone marrow-derived macrophages from EXTL2-/- mice overproduce tumor necrosis factor α (TNFα) and matrix metalloproteinases (MMPs). Conclusions: These results emphasize CSPGs as a prominent modulator of neuroinflammation and they highlight CSPGs accumulating in lesions in promoting axonal injury.