Page 73 - Haematologica March 2020

Cytokine blockade reduces myeloid expansion in RA
significantly different (Figure 1B). While the overall num- ber of BM cells in the femora and tibiae of CIA mice were unchanged, (Figure 1C), Mac-1+Gr1hi BM granulocytes were significantly increased in CIA mice while the num- bers of Mac-1+Gr1intLy6C- immature granulocytes and Mac-1+Gr1intLy6C+ monocytes were unchanged (Figure 1D and Online Supplementary Figure S1B). On the other hand, the numbers of CD19+IgM+ immature B cells and CD19+ IgM- B cells were significantly decreased, as were the numbers of CD4+ and CD8+ T cells (Figure 1D-F and
Online Supplementary Figure S1B). CIA mice were anemic, with significantly decreased hematocrit and hemoglobin levels (Figure 1G). CIA BM was also pale, with decreased basophilic erythroblasts (population II) (Figure 1H, I and Online Supplementary Figure S1B). Altogether, CIA mice exhibited myeloid expansion, consistent with previously published studies using the KRN×G7 genetic autoimmune arthritis model.13 Importantly our findings mirror features of human RA, such as leukocytosis, anemia and immunosenescence.14,15
A
B
CDE
F
GHI
Figure 1. Altered blood system in mice with collagen-induced arthritis. (A) The strategy for producing collagen-induced arthritis (CIA) and representative images show- ing swelling and anklyosis in the hind paws of a CIA mouse and a control (Ctrl) mouse 21 days after disease induction. (B) Peripheral blood (PB) parameters, deter- mined by a complete blood count, of Ctrl and CIA mice (n=5 per group). (C) Total bone marrow (BM) cellularity of hind legs, and (D-F) numbers of the indicated pop- ulations (see Online Supplementary Figure S1 for FACS gating and surface marker definitions) expressed as number per million BM cells (n=6 Ctrl and 11 CIA). (G) Red blood cell parameters in PB (n=5 per group). (H) Representative image of flushed BM. (I) Erythroblast number per million BM cells (n=6 Ctrl and 11 CIA). *P<0.05; **P<0.01 ***P<0.001, as determined by the Mann-Whitney U-test. The data were compiled from three independent experiments. CFA: complete Freund adjuvant; Gr: mature granulocytes; Pre-Gr: immature granulocytes; Mon: monocytes; RBC: red blood cells.
haematologica | 2020; 105(3)
587