Tatiana Salazar

CNS Inflammation and Bone Marrow Neuropathy in Type 1 Diabetes

By using pseudorabies virus expressing green fluorescence protein, we found that efferent bone marrow-neural connections trace to sympathetic centers of the central nervous system in normal mice. However, this was markedly reduced in type 1 diabetes, suggesting a significant loss of bone marrow innervation. This loss of innervation was associated with a change in hematopoiesis toward generation of more monocytes and an altered diurnal release of monocytes in rodents and patients with type 1 diabetes. In the hypothalamus and granular insular cortex of mice with type 1 diabetes, bone marrow-derived microglia/macrophages were activated and found at a greater density than in controls. Infiltration of CD45(+)/CCR2(+)/GR-1(+)/Iba-1(+) bone marrow-derived monocytes into the hypothalamus could be mitigated by treatment with minocycline, an anti-inflammatory agent capable of crossing the blood-brain barrier. Our studies suggest that targeting central inflammation may facilitate management of microvascular complications.

Dicer Expression Exhibits a Tissue-Specific Diurnal Pattern That Is Lost during Aging and in Diabetes

Dysregulation of circadian rhythmicity is identified as a key factor in disease pathogenesis. Circadian rhythmicity is controlled at both a transcriptional and post-transcriptional level suggesting the role of microRNA (miRNA) and double-stranded RNA (dsRNA) in this process. Endonuclease Dicer controls miRNA and dsRNA processing, however the role of Dicer in circadian regulation is not known. Here we demonstrate robust diurnal oscillations of Dicer expression in central and peripheral clock control systems including suprachiasmatic nucleolus (SCN), retina, liver, and bone marrow (BM). The Dicer oscillations were either reduced or phase shifted with aging and Type 2 diabetes. The decrease and phase shift of Dicer expression was associated with a similar decrease and phase shift of miRNAs 146a and 125a-5p and with an increase in toxic Alu RNA. Restoring Dicer levels and the diurnal patterns of Dicer-controlled miRNA and RNA expression may provide new therapeutic strategies for metabolic disease and aging-associated complications.

Increase in acid sphingomyelinase level in human retinal endothelial cells and CD34+ circulating angiogenic cells isolated from diabetic individuals is associated with dysfunctional retinal vasculature and vascular repair process in diabetes

BACKGROUND Diabetic retinopathy is a microvascular disease that results from retinal vascular degeneration and defective repair due to diabetes-induced endothelial progenitor dysfunction. OBJECTIVE Understanding key molecular factors involved in vascular degeneration and repair is paramount for developing effective diabetic retinopathy treatment strategies. We propose that diabetes-induced activation of acid sphingomyelinase (ASM) plays essential role in retinal endothelial and CD34+ circulating angiogenic cell (CAC) dysfunction in diabetes. METHODS Human retinal endothelial cells (HRECs) isolated from control and diabetic donor tissue and human CD34+ CACs from control and diabetic patients were used in this study. ASM messenger RNA and protein expression were assessed by quantitative polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. To evaluate the effect of diabetes-induced ASM on HRECs and CD34+ CACs function, tube formation, CAC incorporation into endothelial tubes, and diurnal release of CD34+ CACs in diabetic individuals were determined. RESULTS ASM expression level was significantly increased in HRECs isolated from diabetic compared with control donor tissue, as well as CD34+ CACs and plasma of diabetic patients. A significant decrease in tube area was observed in HRECs from diabetic donors compared with control HRECs. The tube formation deficiency was associated with increased expression of ASM in diabetic HRECs. Moreover, diabetic CD34+ CACs with high ASM showed defective incorporation into endothelial tubes. Diurnal release of CD34+ CACs was disrupted with the rhythmicity lost in diabetic patients. CONCLUSION Collectively, these findings support that diabetes-induced ASM upregulation has a marked detrimental effect on both retinal endothelial cells and CACs.

Electroacupuncture Promotes Central Nervous System-Dependent Release of Mesenchymal Stem Cells

Electroacupuncture (EA) performed in rats and humans using limb acupuncture sites, LI‐4 and LI‐11, and GV‐14 and GV‐20 (humans) and Bai‐hui (rats) increased functional connectivity between the anterior hypothalamus and the amygdala and mobilized mesenchymal stem cells (MSCs) into the systemic circulation. In human subjects, the source of the MSC was found to be primarily adipose tissue, whereas in rodents the tissue sources were considered more heterogeneous. Pharmacological disinhibition of rat hypothalamus enhanced sympathetic nervous system (SNS) activation and similarly resulted in a release of MSC into the circulation. EA‐mediated SNS activation was further supported by browning of white adipose tissue in rats. EA treatment of rats undergoing partial rupture of the Achilles tendon resulted in reduced mechanical hyperalgesia, increased serum interleukin‐10 levels and tendon remodeling, effects blocked in propranolol‐treated rodents. To distinguish the afferent role of the peripheral nervous system, phosphoinositide‐interacting regulator of transient receptor potential channels (Pirt)‐GCaMP3 (genetically encoded calcium sensor) mice were treated with EA acupuncture points, ST‐36 and LIV‐3, and GV‐14 and Bai‐hui and resulted in a rapid activation of primary sensory neurons. EA activated sensory ganglia and SNS centers to mediate the release of MSC that can enhance tissue repair, increase anti‐inflammatory cytokine production and provide pronounced analgesic relief. Stem Cells 2017;35:1303–1315

Electroacupuncture Promotes CNS-Dependent Release of Mesenchymal Stem Cells.

Electroacupuncture (EA) performed in rats and humans using limb acupuncture sites, LI‐4 and LI‐11, and GV‐14 and GV‐20 (humans) and Bai‐hui (rats) increased functional connectivity between the anterior hypothalamus and the amygdala and mobilized mesenchymal stem cells (MSCs) into the systemic circulation. In human subjects, the source of the MSC was found to be primarily adipose tissue, whereas in rodents the tissue sources were considered more heterogeneous. Pharmacological disinhibition of rat hypothalamus enhanced sympathetic nervous system (SNS) activation and similarly resulted in a release of MSC into the circulation. EA‐mediated SNS activation was further supported by browning of white adipose tissue in rats. EA treatment of rats undergoing partial rupture of the Achilles tendon resulted in reduced mechanical hyperalgesia, increased serum interleukin‐10 levels and tendon remodeling, effects blocked in propranolol‐treated rodents. To distinguish the afferent role of the peripheral nervous system, phosphoinositide‐interacting regulator of transient receptor potential channels (Pirt)‐GCaMP3 (genetically encoded calcium sensor) mice were treated with EA acupuncture points, ST‐36 and LIV‐3, and GV‐14 and Bai‐hui and resulted in a rapid activation of primary sensory neurons. EA activated sensory ganglia and SNS centers to mediate the release of MSC that can enhance tissue repair, increase anti‐inflammatory cytokine production and provide pronounced analgesic relief. Stem Cells 2017;35:1303–1315

Loss of Angiotensin‐Converting Enzyme 2 Exacerbates Diabetic Retinopathy by Promoting Bone Marrow Dysfunction

Angiotensin‐converting enzyme 2 (ACE2) is the primary enzyme of the vasoprotective axis of the renin angiotensin system (RAS). We tested the hypothesis that loss of ACE2 would exacerbate diabetic retinopathy by promoting bone marrow dysfunction. ACE2–/y were crossed with Akita mice, a model of type 1 diabetes. When comparing the bone marrow of the ACE2–/y‐Akita mice to that of Akita mice, we observed a reduction of both short‐term and long‐term repopulating hematopoietic stem cells, a shift of hematopoiesis toward myelopoiesis, and an impairment of lineage–c‐kit+ hematopoietic stem/progenitor cell (HS/PC) migration and proliferation. Migratory and proliferative dysfunction of these cells was corrected by exposure to angiotensin‐1‐7 (Ang‐1‐7), the protective peptide generated by ACE2. Over the duration of diabetes examined, ACE2 deficiency led to progressive reduction in electrical responses assessed by electroretinography and to increases in neural infarcts observed by fundus photography. Compared with Akita mice, ACE2–/y‐Akita at 9‐months of diabetes showed an increased number of acellular capillaries indicative of more severe diabetic retinopathy. In diabetic and control human subjects, CD34+ cells, a key bone marrow HS/PC population, were assessed for changes in mRNA levels for MAS, the receptor for Ang‐1‐7. Levels were highest in CD34+ cells from diabetics without retinopathy. Higher serum Ang‐1‐7 levels predicted protection from development of retinopathy in diabetics. Treatment with Ang‐1‐7 or alamandine restored the impaired migration function of CD34+ cells from subjects with retinopathy. These data support that activation of the protective RAS within HS/PCs may represents a therapeutic strategy for prevention of diabetic retinopathy. Stem Cells 2018;36:1430–1440

Erratum to: CX3CR1 deficiency accelerates the development of retinopathy in a rodent model of type 1 diabetes (Journal of Molecular Medicine, (2016), 94, 11, (1255-1265), 10.1007/s00109-016-1433-0)

The original version of this article unfortunately contains a mistake in Fig. 1a; the wrong figure panels were used. The correct Fig. 1a is shown in this paper.