Fig 2: Decorin suppresses Nf1-OPG formation through microglia NFkB inhibition.a Nf1OPG mouse optic nerves (n = 3) have increased Iκbα phosphorylation relative to WT mice (n = 3). b The increased Iκbα phosphorylation in PBS-treated Nf1OPG mouse optic nerves (n = 3) was reduced by OVA treatment (n = 3). c Activated TCM (act-Tm) increased Iκbα phosphorylation in microglia, which was reduced following the addition of decorin (800 pg/ml). d Decorin (800 pg/ml) blocks the increased p65-NFκB Ser536 phosphorylation induced by activated TCM (act-Tm) treatment (n = 3). e Decorin (800 pg/ml) blocks the increased total p65-NFκB expression, (f) as well as the nuclear localization of p65-NFκB, induced by activated TCM (act-Tm) treatment (n = 3). β-actin and HDAC are used as controls for total protein expression and the nuclear fractions, respectively. g Schematic representation of the NFκB inhibitor treatment used. Nf1OPG mice were treated between 4 and 6 weeks of age with the CAPE NFκB inhibitor (n = 8), whereas control Nf1OPG mice received PBS only (n = 8). Isolated optic nerves were analyzed at 12 weeks of age. h NFκB inhibitor treatment reduced optic glioma volume and (i) proliferation (%Ki67+ cells), as well as microglia (%Iba1+ cells) and T-cell (CD3+) content within the optic nerves of Nf1OPG mice relative to vehicle-treated controls. Two-tailed Student’s t test. j Reduced Ccl5 RNA expression was observed in the optic nerves from Nf1OPG mice treated with the CAPE NFκB inhibitor (NFκB-IN) (n = 5). Two-tailed Student’s t test. k Proposed model of asthma-induced decorin suppression of the Nf1OPG neuron-immune-cancer cell axis. Asthma induces T cell production of decorin, which reduces T cell Ccl4-mediated microglia Ccl5 expression through inhibition of NFκB signaling. Data are presented as the means ± SEM. Exact P values are indicated within each panel. i Scale bars 40 µm. From left to right in each panel: h P = 0.0288; i P = 0.0003, P = 0.0196, P = 0.0025; j P = 0.0018.

Fig 3: Decorin inhibits Nf1-OPG formation.a Decorin (800 pg/ml) attenuated activated TCM (act-Tm)-mediated microglia Ccl5 production (n = 3). Two-tailed Student’s t test. Exact P values are indicated within each panel (ns, not significant). b Decorin reduces microglia Ccl5 production in response to Ccl4 exposure (6 ng/ml) over a physiologic dose range in vitro (n = 4). One-way ANOVA with Bonferroni post hoc correction. Data are presented as the means ± SEM. c TCM (activated T cell-conditioned media) induced microglial Ccl5 production was significantly attenuated by decorin. The addition of Dcn with CCR5 has the greatest inhibition similar to the combination of CCR5 and CCR8 inhibitors (n = 6). One-way ANOVA with Bonferroni post hoc correction. Data are presented as the means ± SEM. d Schematic representation of decorin binding to the CCR8 receptor on microglia, culminating is reduced microglial Ccl5 production by inhibiting NFκB activation. e Schematic representation of decorin treatment of Nf1OPG mice. Nf1OPG mice were treated between 4 and 6 weeks of age with decorin, while control Nf1OPG mice received PBS only. Isolated optic nerves were analyzed at 12 weeks of age. f Decorin treatment has no change on optic nerve volume, but (g) decreased proliferation (%Ki67+ cells) of Nf1OPG mice relative to the vehicle-treated Nf1OPG controls (PBS, n = 8, Decorin, n = 8). No difference in microglia (%Iba1+ cells) or T cell (CD3+ cells) content was observed between decorin-treated mice and their respective controls. Two-tailed Student’s t test (ns, not significant). g Scale bars, 40 µm. From left to right in each panel: a P = 0.0134, b P < 0.0001, P = 0.0035; c P < 0.0001, ns, P = 0.0086, ns; f ns; g P = 0.0010, ns, ns.

Fig 4: Asthma reduces T cell induction of Ccl5 in microglia.a Schematic representation of the mouse Nf1OPG neuron-immune-cancer cell axis in the setting of asthma. b No difference in optic nerve Mdk RNA expression was observed between OVA- (n = 3) or HDM- (n = 3) treated mice and controls (n = 6). Bar graphs represent the means ± SEM of independent biological samples. One-way ANOVA with Bonferroni post hoc correction. c Ccl4 levels are similarly induced with increasing midkine concentrations (0–100 ng/ml) in CD3+ T cells from OVA- and PBS-treated mice. Data are presented as the means ± SEM of n = 3 independent biological samples. One-way ANOVA with Bonferroni post hoc correction. Data are presented as the means ± SEM. d, e Similarly increased CD8+, relative to CD4+, T cell content was detected in the optic nerves of Nf1OPG mice treated with PBS (n = 8), OVA (n = 8) or HDM (n = 8). One-way ANOVA with Bonferroni post hoc correction. Activated T cell medium from (f) OVA- (n = 4) and g HDM- (n = 4) treated mice induced lower levels of microglial Ccl5 relative to PBS-treated Nf1OPG mice. Two-tailed Student’s t test. Similar reductions of Ccl5 expression were observed in CD4+ and CD8+ T cells from (h) OVA- (n = 3) and (i) HDM- (n = 3) treated mice relative to PBS-treated controls (n = 3). One-way ANOVA with Bonferroni post hoc correction. Data are presented as the means ± SEM. d Scale bars, 40 µm. From left to right in each panel: b ns; c ns; ns; ns; ns; e P < 0.0001, P = 0.0022, P = 0.0011; f P = 0.0008; g P = 0.0015; h P = 0.0186, P = 0.0054; i P = 0.0224, P = 0.0007.