Abstract 19493: In Type 1 Diabetes Decreased Bone Marrow Neuronal Support Shifts Normal Hematopoiesis Towards the Generation of (C-C Motif) Receptor 2 Monocytes

Abstract

We previously showed that in both type 1 (T1D) and type 2 diabetes loss of bone marrow innervation leads to circadian dysregulation of hematopoietic stem cell (HSC) release from bone marrow (BM) into the circulation. In this study, we extended these findings to humans with T1D and used T1D rodents to examine the role of key neurotransmitters/neuropeptides in the differentiation and the fate of HSCs. Diabetic (n=5) and control (n=5) subjects underwent a 2 hr blood sampling for 24 hr. Diabetic patients showed an increase in the amplitude of the peak and a phase shift (6 hrs) of the peak compared to controls (p<0.001). In marked contrast, CD34 + cells release in diabetics showed no circadian pattern while controls did. In the long bones of T1D mice, immunodetection of calcitonin gene related peptide was reduced by 65% (p<0.05), neuropeptide Y by 67% (p<0.05), acetylcholine by 51% (p<0.05), and somatostatin by 50% (p<0.05). BM cells from T1D mice showed depletion of Side Population-HSCs but increased numbers of monocyte/macrophage colony forming units. BM supernatant of T1D mice showed increased levels (2.5-fold, p<0.002) of macrophage-colony stimulating factor (M-CSF/CSF-1, a stimulator of monocyte generation) and increased levels IL-1β (2-fold, p<0.05) and IL-27 (3-fold, p<0.01). Chimeric mice (transplanted with gfp-expressing HSC) were made T1D using streptozotocin (n=12) and compared to controls (n=12). T1D retinas, kidneys and brains (enzymatically-dissociated and analyzed by flow cytometry) showed a 10-fold, 6-fold, and 4-fold increase in CD11b + /CD45hi/ (C-C motif) receptor 2 (CCR2 + ) populations compared to controls. Immunohistochemistry of these tissues showed lba + resident microglia that exhibited a ramified morphology suggesting an inflammatory activation by extravasated BM cells. Our data suggests that in diabetic subjects, circadian dysregulation of monocyte and CD34 + cell release exists. Our rodent studies support that the loss of BM neurotransmitter regulation (bone marrow neuropathy) may shift hematopoietic towards the generation of excessive numbers of CCR2 + monocytes and reduced reparative endothelial progenitors which can contribute towards both the vascular and tissue pathology observed in diabetes.