Fig. 2

Chronic expression of cytokines leads to demyelination of subpial cortical layers. Immunofluorescence for MOG and IBA1 shows no demyelination in eGFP vector injected animals (a), but widespread demyelination in the outer cortical layers at 28 days after cytokine lentiviral injection in IFA (b) and MOG (c) immunised animals. A decrease of MOG staining can be seen in IFA animals in the cortical (d) and midline layers (e), which was greater at 56 days in MOG immunised animals (f-g). Areas with loss of MOG at 56 dpi (white box in C) showed similar levels of 200 kd neurofilament protein when compared to naive (h-i). The degree of demyelination was significantly different for both IFA and MOG immunised animals at 28 and 56 days in midline layer I (j), but only in MOG immunised animals in midline layer II-IV, compared to naïve (k)(1-way analysis of variance with Tukey post test, *P < 0.05, ***P < 0.001, ****P < 0.0001, cytokine vs naïve. Δ = p < 0.05, ΔΔ = p < 0.001 IFA vs MOG). Demyelination of cortical layers I-III was significant in MOG immunised animals at both 28 and 56 dpi, but only at 56 days in IFA animals (l). Subpial demyelination also extended in the rostral plane in MOG immunised animals at 56 days (m). Quantification of demyelination 1 mm anterior to the injection site in MOG immunised animals was equal to or greater than at the injection site at both 28 and 56 days after cytokine vector injection (n-p). Immunostaining for the transcription factor Olig2 revealed a substantial reduction in oligodendroglial lineage cells in cortical layers of MOG animals when compared to naïve (q), both for IFA and MOG immunised animals at 28 days post injection in the midline (r) and cortical layers (s), with no significant difference between IFA and MOG immunised animals (data are mean +/−SEM from n = 5–6 animals per group. Statistics: 1-way analysis of variance with Tukey post test. *p < 0.05, **P < 0.01). Scale bars = 300 μm (a-c), 50 μm (d,e)