Figure 5.

SBDS deficiency induces altered BM niche expression of chemokines and selectins after TBI that favor inflammatory cell recruitment. (A) CXCL1, CXCL9, CXCL12, and CCL22 expression by ELISA, demonstrating reductions in all 4 chemokines in BM plasma supernatants of Mx1^CreSbds^Exc (n = 5) vs control mice (n = 6) 48 hours after 1100-cGy TBI. (B) CXCL13, CCL3, and CCL9 expression by ELISA demonstrating increases in these proinflammatory chemokines in BM plasma harvested from Mx1^CreSBDS^Exc (n = 5) vs controls (n = 6) at 48 hours after 1100-cGy TBI. (C) Immunohistochemistry staining demonstrates lower CXCL12 expression in BM from Mx1^CreSbds^Exc mice compared with controls at 48 hours after 1100-cGy TBI. Arrowheads indicate CXCL12-positivity surrounding megakaryocytes. Scale bar: 500 µm for the first column and 50 µm for the second column. (D) Representative dot plots (top) show gating strategies used to define CD45⁺CD41⁺ megakaryocytes in post-TBI BM. Mx1^CreSBDS^Exc mice (n = 5) exhibit a trend toward decreased numbers of CD45⁺CD41⁺ megakaryocytes in the BM niche than controls (n = 7) at 24 hours after 1100-cGy TBI (bottom). P = 0.06; Student t-test. (E) P- and E-selectin levels by ELISA in BM cell lysates and BM supernatants, respectively, demonstrating lower P-selectin but higher E-selectin levels in Mx1^CreSbds^Exc (n = 5) vs control mice (n = 6) 48 hours after 1100-cGy TBI. (F) mRNA expression of Selplg (encodes P-selectin) and Sele (encodes E-selectin) in BM stromal cells of irradiated (24 hours after 1100-cGy TBI) Mx1^CreSBDS^Exc mice compared with controls (n = 5 mice per group). *P < .05; **P < .01; ***P < .001; Student t-test used for ELISA data or DESeq2 statistical test for RNA-seq data.