Figure 4. MATN2 is released from neurons following axonal injury in spinal cord lesions.

(A) Colabeling for MATN2, synaptophysin, and pan-neurofilament (NF) (top) in acute spinal cord lesions showing clear intraaxonal as well as extraaxonal MATN2 expression. Scale bar: 12.5 μm (top); 1.5 μm (bottom). (B) Confocal 3D image showing colabeling for MATN2 and neurofilament (NF) in an acute spinal cord lesion. Scale bar: 1.5 μm. (C) Matn2 expression (mean ± SEM, qRT-PCR) in mono- and cocultures following 24-hour LPS addition shows increased Matn2 expression in LPS-treated cocultures (n = 6–9 per group). Gene expression is shown relative to untreated cultures. ***P < 0.001, P ≥ 0.5 = not significant, 2-way ANOVA. (D) Immunoblot analysis reveals specific MATN2 protein expression in WT neuron (WT n) cultures compared with KO controls (KO n) and is increased in cocultures following LPS addition (24 hours). WT m, WT macrophage; rec. MATN2, recombinant MATN2. (E) Colabeling for MATN2 and IBA-1 or GFAP, RIP, or CD3 in acute spinal cord lesions demonstrates close association of MATN2 with macrophages (inset). No colocalization was detected. Nuclei were visualized with DAPI. Scale bar: 10 μm; 2.5 μm (inset).