Sarah Jahn

Brief secondhand smoke exposure depresses endothelial progenitor cells activity and endothelial function: sustained vascular injury and blunted nitric oxide production.

OBJECTIVES This study sought to analyze the effects of acute secondhand smoke (SHS) exposure on the number and function of endothelial progenitor cells (EPCs) over 24 h. BACKGROUND Secondhand smoke increases the risk of vascular disease and is a major public health concern, but the mechanism(s) of action are not fully understood. METHODS Healthy nonsmokers (age SEM 30.3 +/- 1.3 years, n = 10) were exposed to 30 min of SHS yielding cotinine levels commonly observed in passive smokers and to smokefree air on 2 separate days. Measurements were taken before exposure (baseline), immediately after (0 h), and at 1 h, 2.5 h, and 24 h after. The EPCs (CD133(+)/KDR(+), CD34(+)/KDR(+)) and endothelial microparticles (EMPs: CD31(+)/CD41(-), CD144(+), CD62e(+)) were determined in blood using flow cytometry. The EPC chemotaxis toward vascular endothelial growth factor was measured. Endothelial function was assessed as flow-mediated dilation (FMD) using ultrasound. RESULTS Secondhand smoke exposure increased EPCs and plasma vascular endothelial growth factor and completely abolished EPC chemotaxis during 24 h after exposure. Secondhand smoke increased EMPs and decreased FMD. Although FMD returned to baseline at 2.5 h, EMPs and vascular endothelial growth factor levels remained elevated at 24 h, suggesting endothelial activation and injury with functional impairment of the vascular endothelium. Exposure to smokefree air had no effect. Incubation of EPCs from nonexposed subjects with plasma isolated from SHS-exposed subjects in vitro decreased chemotaxis by blockade of vascular endothelial growth factor-stimulated nitric oxide production. CONCLUSIONS Brief exposure to real-world levels of SHS leads to sustained vascular injury characterized by mobilization of dysfunctional EPCs with blocked nitric oxide production. Our results suggest that SHS not only affects the vascular endothelium, but also the function of EPCs.

Improvement of Endothelial Function With Dietary Flavanols Is Associated With Mobilization of Circulating Angiogenic Cells in Patients With Coronary Artery Disease

OBJECTIVES In patients with coronary artery disease (CAD) medically managed according to currently accepted guidelines, we tested whether a 1-month dietary intervention with flavanol-containing cocoa leads to an improvement of endothelial dysfunction and whether this is associated with an enhanced number and function of circulating angiogenic cells (CACs). BACKGROUND Dietary flavanols can improve endothelial dysfunction. The CACs, also termed endothelial progenitor cells, are critical for vascular repair and maintenance of endothelial function. METHODS In a randomized, controlled, double-masked, cross-over trial, 16 CAD patients (64+/-3 years of age) received a dietary high-flavanol intervention (HiFI [375 mg]) and a macronutrient- and micronutrient-matched low-flavanol intervention (LoFI [9 mg]) twice daily in random order over 30 days. RESULTS Endothelium-dependent vasomotor function, as measured by flow-mediated vasodilation of the brachial artery, improved by 47% in the HiFI period compared with the LoFI period. After HiFI, the number of CD34+/KDR+-CACs, as measured by flow cytometry, increased 2.2-fold as compared with after LoFI. The CAC functions, as measured by the capacity to survive, differentiate, proliferate, and to migrate were not different between the groups. The HiFI led to a decrease in systolic blood pressure (mean change over LoFI: -4.2+/-2.7 mm Hg), and increase in plasma nitrite level (mean change over LoFI: 74+/-32 nM). Applying a mixed-effects linear regression model, the results demonstrated a significant increase in flow-mediated vasodilation and a decrease in systolic blood pressure with increasing levels of CD34+/KDR+-CACs. CONCLUSIONS Sustained improvements in endothelial dysfunction by regular dietary intake of flavanols are associated with mobilization of functional CACs. (Effect of Cocoa Flavanols on Vascular Function in Optimally Treated Coronary Artery Disease Patients: Interaction Between Endothelial Progenitor Cells, Reactivity of Micro- and Macrocirculation; NCT00553774).

Rituximab Efficiently Depletes Increased CD20-Expressing T Cells in Multiple Sclerosis Patients

In multiple sclerosis (MS), B cell–depleting therapy using monoclonal anti-CD20 Abs, including rituximab (RTX) and ocrelizumab, effectively reduces disease activity. Based on indirect evidence, it is generally believed that elimination of the Ag-presenting capabilities and Ag nonspecific immune functions of B cells underlie the therapeutic efficacy. However, a small subset of T lymphocytes (T cells) was shown to also express CD20, but controversy prevails surrounding the true existence of this T cell subpopulation. Using single-cell imaging flow cytometry and expression profiling of sorted lymphocyte subsets, we unequivocally demonstrate the existence of CD3+CD20dim T cells. We show that in MS patients, increased levels of CD3+CD20dim T cells are effectively depleted by RTX. The pathological relevance of this T cell subset in MS remains to be determined. However, given their potential proinflammatory functionality, depletion of CD20-expressing T cells may also contribute to the therapeutic effect of RTX and other mAbs targeting CD20.

Nitric Oxide Synthase Expression and Functional Response to Nitric Oxide Are Both Important Modulators of Circulating Angiogenic Cell Response to Angiogenic Stimuli

Objective—Circulating angiogenic cells (CACs), also termed endothelial progenitor cells, play an integral role in vascular repair and are functionally impaired in coronary artery disease (CAD). The role of nitric oxide (NO) in CAC function is poorly understood. We hypothesized that CAC migration toward angiogenic signals is modulated by both NO synthase (NOS) expression and functional response to NO. Methods and Results—Similar to endothelial cells, CAC chemotaxis to vascular endothelial growth factor (VEGF) was blocked by inhibition of NOS, phosphatidylinositol 3-kinase, or guanylyl cyclase or by treatment with an NO scavenger. Addition of an NO donor (S-nitroso-N-acetylpenicillamine) and the NOS substrate l-arginine increased random cell migration (chemokinesis) and enhanced VEGF-dependent chemotaxis. Healthy CACs expressed endothelial NOS, but endothelial NOS was not detected in CAD patient CACs. Both chemokinesis and chemotaxis to VEGF of patient CACs were decreased compared with healthy CACs but were restored to healthy values by S-nitroso-N-acetylpenicillamine. In parallel, CAD patients exhibited lower flow-mediated vasodilation and plasma NO source nitrite than young, healthy subjects, indicating endothelial dysfunction with reduced NO bioavailability. Conclusion—NOS activity is required for CAC chemotaxis. In CAD patients, impairment of NOS expression and NO bioavailability, rather than response to NO, may contribute to dysfunction of CACs and limit their regenerative capacity.

Cytokine Combination Therapy With Long-Acting Erythropoietin and Granulocyte Colony Stimulating Factor Improves Cardiac Function But is Not Superior Than Monotherapy in a Mouse Model of Acute Myocardial Infarction

BACKGROUND Erythropoietin (EPO) and granulocyte colony stimulating factor (GCSF) are potential novel therapies after myocardial infarction (MI). We first established the optimal and clinically applicable dosages of these drugs in mobilizing hematopoietic stem cells (HSC), and then tested the efficacy of monotherapy and combination therapy post-MI. METHODS AND RESULTS Optimal doses were established in enhanced green fluorescent protein (eGFP) + chimeric mice (n = 30). Next, mice underwent MI and randomized into 4 groups (n = 18/group): 1) GCSF; 2) EPO; 3) EPO+GCSF; and 4) control. Left ventricular (LV) function was analyzed pre-MI, at 4 hours and at 28 days post-MI. Histological assessment of infarct size, blood vessels, apoptotic cardiomyocytes, and engraftment of eGFP+ mobilized cells were analyzed at day 28. LV function in the control group continued to deteriorate, whereas all treatments showed stabilization. The treatment groups resulted in less scarring, increased numbers of mobilized cells to the infarct border zone (BZ), and a reduction in the number of apoptotic cardiomyocytes. Both EPO groups had significantly more capillaries and arterioles at the BZ. CONCLUSION We have established the optimal doses for EPO and GCSF in mobilizing HSC from the bone marrow and demonstrated that therapy with these agents, either as monotherapy or combination therapy, led to improvement of cardiac function post-MI. Combination therapy does not seem to have additive benefit over monotherapy in this model.

The myelin oligodendrocyte glycoprotein directly binds nerve growth factor to modulate central axon circuitry.

Myelin oligodendrocyte glycoprotein, expressed on the outermost lamellae of the myelin sheath, is a novel and specific binding partner for NGF that may modulate local concentrations of the neurotrophin in the spinal cord microenvironment.