Smoke exposure and circulating progenitor cells: evidence for modulation of antioxidant enzymes and cell count

Cigarette Smoke-Induced Reactive Oxygen Species Formation: A Concise Review

Smoking is recognized as a significant risk factor for numerous disorders, including cardiovascular diseases, respiratory conditions, and various forms of cancer. While the exact pathogenic mechanisms continue to be explored, the induction of oxidative stress via the production of excess reactive oxygen species (ROS) is widely accepted as a primary molecular event that predisposes individuals to these smoking-related ailments. This review focused on how cigarette smoke (CS) promotes ROS formation rather than the pathophysiological repercussions of ROS and oxidative stress. A comprehensive analysis of existing studies revealed the following key ways through which CS imposes ROS burden on biological systems: (1) ROS, as well as radicals, are intrinsically present in CS, (2) CS constituents generate ROS through chemical reactions with biomolecules, (3) CS stimulates cellular ROS sources to enhance production, and (4) CS disrupts the antioxidant system, aggravating the ROS generation and its functions. While the evidence supporting these mechanisms is chiefly based on in vitro and animal studies, the direct clinical relevance remains to be fully elucidated. Nevertheless, this understanding is fundamental for deciphering molecular events leading to oxidative stress and for developing intervention strategies to counter CS-induced oxidative stress.

Reduced Circulating Endothelial Progenitor Cells and Downregulated GTCPH I Pathway Related to Endothelial Dysfunction in Premenopausal Women with Isolated Impaired Glucose Tolerance

Background

Individuals at a prediabetic stage have had an augmented cardiovascular disease (CVD) risk and CVD-related mortality compared to normal glucose tolerance (NGT) individuals, which may be attributed to the impaired vascular endothelial repair capacity. In this study, circulating endothelial progenitor cells' (EPCs) number and activity were evaluated, and the underlying mechanisms in premenopausal women with impaired glucose regulation were explored.

Methods

Circulating EPCs' number and activity and flow-mediated dilation (FMD) were compared in premenopausal women with NGT, isolated impaired fasting glucose (i-IFG), or isolated impaired glucose tolerance (i-IGT). Plasma nitric oxide (NO), EPCs-secreted NO, and intracellular BH4 levels were also measured. The key proteins (Tie2, Akt, eNOS, and GTPCH I) in the guanosine triphosphate cyclohydrolase/tetrahydrobiopterin (GTPCH/BH4) pathway and Tie2/Akt/eNOS signaling pathway were evaluated in these women.

Results

It was observed that the i-IGT premenopausal women not i-IFG premenopausal women had a significant reduction in circulating EPCs' number and activity as well as reduced FMD when compared to NGT subjects. Plasma NO levels or EPCs-secreted NO also decreased only in i-IGT women. The expression of GTCPH I as well as intracellular BH4 levels declined in i-IGT women; however, the alternations of key proteins' expression in the Tie2/Akt/eNOS signaling pathway were not observed in either i-IGT or i-IFG women.

Conclusions

The endothelial repair capacity was impaired in i-IGT premenopausal women but was preserved in i-IFG counterparts. The underlying mechanism may be associated with the downregulated GTCPH I pathway and reduced NO productions.

Elevated Inflammatory Parameter Levels Negatively Impact Populations of Circulating Stem Cells (CD133+), Early Endothelial Progenitor Cells (CD133+/VEGFR2+), and Fibroblast Growth Factor in Stroke Patients

BACKGROUND

Endothelial Progenitor Cells (EPCs) are important players in neovascularization, mobilized through signalling by Angiogenic Growth Factors (AGFs) such as Vascular Endothelial Growth Factor (VEGF) and fibroblast growth factor (FGF). In vitro, inflammatory parameters impair the function and influence of EPCs on AGFs. However, this connection is not clear in vivo. To understand the mechanisms of augmented arteriogenesis and angiogenesis in acute ischemic stroke (AIS) patients, we investigated whether circulating stem cells (CD133+), early endothelial progenitor cells (CD133+/VEGFR2+), and endothelial cells (ECs; CD34¯/CD133¯/VEGFR2+) were increasingly mobilized during AIS, and whether there were correlations between EPC levels, growth factor levels and inflammatory parameters.

METHODS

Data on demographics, classical vascular risk factors, neurological deficit information (assessed using the National Institutes of Health Stroke Scale), and treatment were collected from 43 consecutive AIS patients (group I). Risk factor control patients (group II) included 22 nonstroke subjects matched by age, gender, and traditional vascular risk factors. EPCs were measured by flow cytometry and the populations of circulating stem cells (CD133+), early EPCs (CD133+/VEGFR2+), and ECs (CD34¯/CD133¯/VEGFR2+) were analysed. Correlations between EPC levels and VEGF and FGF vascular growth factor levels as well as the influence of inflammatory parameters on EPCs and AGFs were assessed.

RESULTS

Patient ages ranged from 54 to 92 years (mean age 75.2 ± 11.3 years). The number of circulating CD34¯/CD133¯/VEGF-R2+ cells was significantly higher in AIS patients than in control patients (p < 0.05). VEGF plasma levels were also significantly higher in AIS patients compared to control patients on day 7 (p < 0.05). FGF plasma levels in patients with AIS were significantly higher than those in the control group on day 3 (p < 0.05). There were no correlations between increased VEGF and FGF levels and the number of CD133+, CD133+/VEGFR2+, or CD34¯/CD133¯/VEGFR2+ cells. Leukocyte levels, FGF plasma levels, and the number of early EPCs were negatively correlated on day 3. High sensitivity C-reactive protein levels and the number of CD133+ and CD133+/VEGFR2+ cells were negatively correlated on day 7. In addition, there was a negative correlation between fibrinogen levels and FGF plasma levels as well as the number of early EPCs (CD133+/VEGFR2+).

CONCLUSION

AIS patients exhibited increased numbers of early EPCs (CD133+/VEGFR2+) and AGF (VEGF and FGF) levels. A negative correlation between inflammatory parameters and AGFs and EPCs indicated the unfavourable influence of inflammatory factors on EPC differentiation and survival. Moreover, these correlations represented an important mechanism linking inflammation to vascular disease.

Abnormal left ventricular global strain during exercise-test in young healthy smokers

Background. It is unknown how much precociously the cigarette smoking (CS) may compromise the integrity of the cardiovascular (CV) system. Myocardial function can be routinely assessed by conventional echocardiography, but abnormalities are only detected when somewhat a remodelling has already occurred. These limitations could be overcome by strain imaging. Methods. We evaluated whether young smokers with normal left ventricular (LV) geometry, wall motion and ejection fraction may present abnormalities in myocardial deformation, both at rest and during physical effort. We selected 50 young smokers with no additional CV risk factors, and 60 non-smokers to undergo a standardized exercise-test. Consistently, we evaluated the CV adaptation to exercise by both conventional echocardiography and speckle-tracking analysis (2D-STE). Results. We found no difference between smokers and controls regarding baseline characteristics; as expected, smokers presented with lower HDL-cholesterol (p < 0.005), and higher fibrinogen, C-reactive protein (CRP), and interleukin-6 (p < 0.001). Conventional echocardiography parameters were not different between groups, while we detected a different behaviour of global longitudinal strain (GLS), global circumferential strain (GCS) and twist by 2D-STE during exercise-test. Indeed, GLS, GCS and twist behaved differently during exercise test in smokers with respect to controls. We found an association between CS, inflammation and LV mechanics changes uncovered by physical effort, and regression analysis confirmed that the intensity of the exposure to cigarette smoking, together with the inflammatory status (CRP, fibrinogen and Il-6) plasma levels, drive this impairment. Conclusions. We confirm strain imaging (2D-STE) as a very useful tool to identify early changes in cardiac mechanics, as adaptation to exercise; our findings may reflect a very precocious functional abnormality in active smokers, likely long before structural damage occurs.

Attenuated endothelial function is associated with decreased endothelial progenitor cells and nitric oxide in premenopausal diabetic women

Previous studies have demonstrated that the deleterious effect of diabetes mellitus (DM) on the risk of cardiovascular disease also occurs in premenopausal women, in spite of their relatively high estrogen levels; however, the underlying mechanism remains unclear. The present study aimed to investigate the sex‑related differences in circulating endothelial progenitor cells (EPCs) in a relatively young population with type 2 DM (T2DM) and its underlying mechanism. The number and functional activity of circulating EPCs, and vascular endothelial function assessed using flow‑mediated dilation (FMD), were compared in premenopausal women and age‑matched men with or without T2DM. Nitric oxide (NO) in the plasma or NO secreted by EPCs was also measured. The number and activity of circulating EPCs, and NO levels in the plasma or culture medium, were lower in premenopausal women with T2DM compared with those without T2DM. In addition, the number and activity of circulating EPCs and NO levels were decreased in men with T2DM compared with in age‑matched premenopausal women with T2DM. FMD was positively correlated with the number and activity of circulating EPCs, and NO levels. In conclusion, DM in premenopausal women may significantly impair the repair capability of EPCs and lead to endothelial dysfunction, which may be associated with reduced NO production. In patients with both DM and normal glucose tolerance, sex‑related differences of EPCs are presented in a young population.

Effects of Angiotensin-Converting Enzyme Inhibition on Circulating Endothelial Progenitor Cells in Patients with Acute Ischemic Stroke

Background

Therapeutic neovascularization might represent an important strategy to salvage tissue after ischemia. Circulating bone marrow-derived endothelial progenitor cells (EPCs) were previously shown to augment the neovascularization of ischemic tissue. Angiotensin-converting enzyme inhibitors (ACEIs) might modulate EPC mobilization. We evaluated populations of circulating stem cells and early EPCs in acute ischemic stroke (AIS) patients and the effect of ACEI on circulating EPCs in these patients with respect to aspects of stroke pathogenesis.

Methods

We studied 43 AIS patients (group I), comprising 33 treated with ACEI (group Ia) and 10 untreated (group Ib). Risk factor controls (group II) included 22 subjects. EPCs were measured by flow cytometry.

Results

In AIS patients, the number of circulating stem cells and early EPCs upon admission was similar to that in control group individuals. There were no significant differences in the numbers of stem cells and early EPCs over subsequent days after AIS. There were also no significant differences in stem cell and early EPC numbers over the first 3 days between group Ia and group Ib. However, on day 7, these numbers were significantly higher in group Ib than in group Ia (p < 0.05). In AIS patients chronically treated with ACEI, there was a negative correlation between CD133⁺ cell number and neurological deficit on the first, third, and seventh days (p < 0.005).

Conclusions

An increased number of circulating stem cells and early EPCs were not observed in stroke patients chronically treated with ACEI. In patients chronically treated with ACEI, a significant correlation was observed between decreased neurological deficit and higher levels of CD133⁺ cells; this could be due to the positive influence of these cells on the regeneration of the endothelium and improved circulation in the ischemic penumbra.

Circulating progenitor cells in hypertensive subjects: Effectiveness of a treatment with olmesartan in improving cell number and miR profile in addition to expected pharmacological effects

CD34+ circulating progenitor cells (CD34+CPCs) are a population of multipotent cells which can delay the development of atherosclerosis and cardiovascular disease (CVD) in conditions of increased CV risk. MicroRNAs (miRs) 221 and 222 modulate different genes regulating angiogenesis and inflammation; moreover, miR221/22 have beenshown to participate in differentiation and proliferation of CD34+CPCs, inhibiting cell migration and homing. miR221/222 in CD34+CPCs from hypertensive subjects are also increased and associated with CD34+cell number and reactive oxygen species (ROS). We evaluated CD34+CPC number, intracellular miR221/222 and ROS levels, arterial stiffness (AS)and echocardiography indices at baseline (T0).Then, after a six-month treatment with olmesartan, 20 mg/day (T1), in 57 hypertensive patients with left ventricular hypertrophy (LVH) and with no additional risk factor for CVD, and in 29 healthy controls (baseline),fibrinogen, C-reactive protein (CRP), glucose and lipid profiles were also evaluated.At T1, blood pressure values, CRP and fibrinogen levels, ROS and miR221/222 were significantly decreased (all p <0.001), as were AS indices and LV mass index (p<0.001), while cell number was increased (p<0.001). Olmesartan is effective in reducing miR and ROS levels in CD34+CPCs from hypertensive subjects, as well as in increasing CD34+CPC number, providing multilevel CV protection, in addition to its expected pharmacological effects.

Endothelial Progenitor Cells for Diagnosis and Prognosis in Cardiovascular Disease

Objective. To identify, evaluate, and synthesize evidence on the predictive power of circulating endothelial progenitor cells (EPCs) in cardiovascular disease, through a systematic review of quantitative studies. Data Sources. MEDLINE was searched using keywords related to "endothelial progenitor cells" and "endothelium" and, for the different categories, respectively, "smoking"; "blood pressure"; "diabetes mellitus" or "insulin resistance"; "dyslipidemia"; "aging" or "elderly"; "angina pectoris" or "myocardial infarction"; "stroke" or "cerebrovascular disease"; "homocysteine"; "C-reactive protein"; "vitamin D". Study Selection. Database hits were evaluated against explicit inclusion criteria. From 927 database hits, 43 quantitative studies were included. Data Syntheses. EPC count has been suggested for cardiovascular risk estimation in the clinical practice, since it is currently accepted that EPCs can work as proangiogenic support cells, maintaining their importance as regenerative/reparative potential, and also as prognostic markers. Conclusions. EPCs showed an important role in identifying cardiovascular risk conditions, and to suggest their evaluation as predictor of outcomes appears to be reasonable in different defined clinical settings. Due to their capability of proliferation, circulation, and the development of functional progeny, great interest has been directed to therapeutic use of progenitor cells in atherosclerotic diseases. This trial is registered with registration number: Prospero CRD42015023717.

Oxidative stress, mitochondrial perturbations and fetal programming of renal disease induced by maternal smoking

An adverse in-utero environment is increasingly recognized to predispose to chronic disease in adulthood. Maternal smoking remains the most common modifiable adverse in-utero exposure leading to low birth weight, which is strongly associated with chronic kidney disease (CKD) in later life. In order to investigate underlying mechanisms for such susceptibility, female Balb/c mice were sham or cigarette smoke-exposed (SE) for 6 weeks before mating, throughout gestation and lactation. Offspring kidneys were examined for oxidative stress, expression of mitochondrial proteins, mitochondrial structure as well as renal functional parameters on postnatal day 1, day 20 (weaning) and week 13 (adult age). From birth throughout adulthood, SE offspring had increased renal levels of mitochondrial-derived reactive oxygen species (ROS), which left a footprint on DNA with increased 8-hydroxydeoxyguanosin (8-OHdG) in kidney tubular cells. Mitochondrial structural abnormalities were seen in SE kidneys at day 1 and week 13 along with a reduction in oxidative phosphorylation (OXPHOS) proteins and activity of mitochondrial antioxidant Manganese superoxide dismutase (MnSOD). Smoke exposure also resulted in increased mitochondrial DNA copy number (day 1-week 13) and lysosome density (day 1 and week 13). The appearance of mitochondrial defects preceded the onset of albuminuria at week 13. Thus, mitochondrial damage caused by maternal smoking may play an important role in development of CKD at adult life.

Circulating progenitor cells in hypertensive patients with different degrees of cardiovascular involvement

We investigated whether different degrees of hypertension-related cardiovascular involvement are associated with changes in circulating proangiogenic hematopoietic cell (PHC) numbers and/or phenotypes and/or in the PHC redox system in hypertensive individuals with isolated arterial stiffening (AS) hypertensives or with both carotid intima-media thickening and left ventricular hypertrophy (LVH) hypertensives. We also evaluated microRNA (miRs) 221 and 222 (miRs221/222) expression in CD34+ cells, the relationship between these miRs and cell number and reactive oxygen species (ROS) levels, and the expression of manganese superoxide dismutase (MnSOD), catalase (CAT) glutathione peroxidase type-1 (GPx-1) and gp91phox-containing nicotinamide-adenine-dinucleotide-phosphate-oxidase (NOX2). Proangiogenic hematopoietic cells (PHCs) from hypertensive patients and controls were isolated by flow cytometry. PHCs were higher in hypertensives than in controls but were lower in LVH than in AS hypertensives. In CD34+ cells from AS hypertensives, NOX2, MnSOD, CAT and GPx-1 were overexpressed; ROS, miRs and NOX2 were also increased and were associated with cell number. In LVH, we found an imbalance in the cell redox system; MnSOD showed the highest values, whereas CAT and GPx-1 were lower than in AS hypertensives. Intracellular ROS, miRs and NOX2 were higher and inversely associated with cell number. In AS hypertensives, the redox balance may sustain the increase in PHCs; by contrast, in hypertensives with more advanced lesions, redox imbalance may result in increased oxidative stress and cell reduction.

Circulating progenitor cells in rheumatoid arthritis: association with inflammation and oxidative stress

OBJECTIVES

To evaluate the association between inflammation, oxidative stress, and circulating progenitor cell (CPC) number and redox equilibrium, vascular lesions and accelerated atherosclerosis in rheumatoid arthritis (RA).

METHOD

Circulating CD34+ cells were isolated from 33 RA patients and 33 controls. Reactive oxygen species (ROS) levels and mRNA expression of manganese superoxide dismutase (MnSOD), catalase (CAT), glutathione peroxidase type 1 (GPx-1) antioxidant enzymes, and the gp91phox-containing nicotinamide adenine dinucleotide phosphate (NADPH) oxidase NOX2 were measured in CD34+ cells. C-reactive protein (CRP), fibrinogen, erythrocyte sedimentation rate (ESR), carotid intima-media thickness (cIMT), and arterial stiffness (AS) were also evaluated. We investigated the relationships between inflammatory markers, vascular parameters, cell number, and antioxidant enzymes.

RESULTS

CD34+ cell number was lower in RA patients than in controls. In CD34+ cells from RA patients, ROS levels, MnSOD mRNA, and NOX2 mRNA were higher, while mRNA expression of GPx-1 and CAT was significantly lower. The AS, pulse wave velocity (PWV), and augmentation index (AIx) were higher, as was cIMT. CD34+ cell number was inversely correlated with CRP, ROS, PWV, and AIx, and with the CAT/MnSOD and GPx-1/MnSOD ratios. CRP was correlated with MnSOD mRNA, PWV, and AIx but not with CAT and GPx-1 mRNA.

CONCLUSIONS

Our data show a link between inflammation, oxidative stress, and the impairment of the antioxidant system of CPCs and their number, and with arterial stiffness in RA subjects. This could suggest a perspective on the accelerated development of vascular damage and atherosclerosis in RA.

C-Kit/c-Kit ligand interaction of bone marrow endothelial progenitor cells is influenced in a cigarette smoke extract-induced emphysema model

BACKGROUND

Smoking causes lung endothelial cell apoptosis and emphysema. Derived from bone marrow, circulating endothelial progenitor cells (EPCs) maintain vascular integrity by replacing and repairing damaged endothelial cells. Smoking influences the number of circulating EPCs. Recruitment of EPCs from bone marrow to peripheral blood depends on the interaction of c-Kit/soluble c-Kit ligand (sKitL). We hypothesized that smoking might influence c-Kit(+) EPCs/sKitL interaction in bone marrow in the development of smoking-related emphysema. In this study, we used a cigarette smoke extract (CSE)-induced emphysema model.

METHODS

Mice were injected intraperitoneally with PBS/CSE and sacrificed at day 28. Lung function and pathology of lung tissue were measured to characterize the model. Expressions of c-Kit in the lung tissue were assayed. Bone marrow cells were isolated by red blood cell lysis. EPCs/c-Kit(+) EPCs in nonred blood cells were analyzed by flow cytometry. Expressions of KitL and MMP-9, and activity MMP-9 in bone marrow were measured.

RESULTS

Our data demonstrated that gene and protein expressions of c-Kit were decreased in the lung tissue in this model. Compared with the control group, the number of bone marrow nonred blood cells was unchanged following CSE treatment, while the depletion of bone marrow EPCs/c-Kit(+) EPCs was significant. The level of sKitL was reduced in the bone marrow in the model. The reduction of sKitL was associated with deregulated KitL expression and decreased MMP-9 activity.

CONCLUSIONS

The interaction between c-Kit and sKitL in bone marrow EPCs, a critical step in endothelial repair, is negatively affected in a CSE-induced emphysema model.

Assessment of some biochemical oxidative stress markers in male smokers with chronic periodontitis

The present study aims to assess and compare the biochemical oxidative stress markers in male smokers and non-smokers with chronic periodontitis. One hundred thirty-four male chronic periodontitis patients and 64 apparently healthy male volunteers were recruited for the study. The periodontal status was evaluated by measuring gingival index, plaque index, papillary bleeding index and clinical attachment loss using UNC-15 probe. The biochemical markers estimated were total antioxidant capacity, RBC-superoxide dismutase, glutathione peroxidase, vitamin C, malondialdehyde and C-reactive protein. The obtained results indicate higher oxidative stress in chronic periodontitis. Smokers with chronic periodontitis show significantly higher periodontal clinical parameters and relatively higher systemic oxidative stress. Vitamin C estimation may be an important biochemical parameter in conjunction with clinical parameters for diagnosis of chronic periodontitis in smokers.

Circulating progenitor cells and the elderly: a seven-year observational study

Cardiovascular (CV) diseases and related complications are the main causes of morbidity and mortality in the elderly. CV progenitor cells, including CD34+ cells, play a role in delaying the progression of atherosclerosis. In the present study we observed 100 octogenarians for seven years, in order to address the question of whether CD34+ cell number is a predictor of longevity in selected survivors. We also checked for associations of cell expression of manganese superoxide dismutase (Mn-SOD), catalase (CAT), and glutathione peroxidase type-1 (GPx-1) antioxidative enzymes, with number of CD34+ progenitor cells and mortality. We found that in very old subjects the number of CD34+ cells at baseline were higher in subjects who reached older age at death or were still living at the end of observation period, with respect to subjects who died from all causes, including CV deaths. On the other hand, HDL-C plasma levels and, with the exception of diabetes, the classic CV risk factors (hypertension, smoking, hypercholesterolemia) showed a loss of their predictive power. A significant association between the redox system of CD34+ cells and mortality was also observed. These data suggest that, even in the elderly, CD34+ cells maintain their role in predicting mortality. CD34+ cells could thus be considered as a biomarker of longevity.

The ontogeny of endothelial progenitor cells through flow cytometry

PURPOSE OF REVIEW

Since the discovery of endothelial progenitor cells (EPCs), there have been conflicting reports as to the precise phenotypic identity, and thus an accurate description of the function of these cells in disease pathology is lacking. This review will detail the protocols that have been published within 2010 to help decipher the true identity of the various cells that have been reported as EPCs in numerous clinical trials.

RECENT FINDINGS

Throughout 2010, three protocols have been published alleging to identify EPCs, yet only one provides a true nonhematopoietic origin for a cell that is classified as an EPC. In addition to the protocols published to try to establish a consensus definition, 10 studies involving EPCs across disease pathologies were published with various degrees of correlation to disease phenotype and cellular level.

SUMMARY

A true phenotypic definition of a circulating EPC capable of becoming an endothelial colony forming cell with proliferative potential has been given. It is now time the EPC field drops this ambiguous term (i.e. EPCs), as many studies purporting to measure EPCs are in fact still quantifying cells of a hematopoietic origin. It is necessary for cross study comparisons that a uniform phenotypic definition be adhered to when using the term EPC.