Molecular characterization and potential function of Rxrγ in gonadal differentiation of Chinese soft-shelled turtle (Pelodiscus sinensis).

Retinoid X receptor (RXR) is a member of the ligand-dependent nuclear receptor family. Previous studies revealed that RXRs are involved in reproduction in vertebrates. However, information on the function of RXRs in turtles is scarce. In this study, the Rxrγ cDNA sequence of Pelodiscus sinensis was cloned and analyzed, and a polyclonal antibody was constructed. RXRγ protein showed a positive signal in both mature and differentiated gonads of the turtle. Subsequently, the function of the Rxrγ gene in gonadal differentiation was confirmed using short interfering RNA (RNAi). The full-length cDNA sequence of the Rxrγ gene in P. sinensis was 2152 bp, encoding 407 amino acids and containing typical nuclear receptor family domains, including the DNA-binding domain (DBD), ligand-binding domain (LBD), and activation function 1 (AF1). Moreover, gonadal Ps-Rxrγ showed sexual dimorphism expression patterns in differentiated gonads. Real-time quantitative PCR results revealed that the Rxrγ gene was highly expressed in the turtle ovary. RNAi treatment increased the number of Sertoli cells in ZZ embryonic gonads. Furthermore, RNA interference upregulated Dmrt1 and Sox9 in ZZ and ZW embryonic gonads. However, Foxl2, Cyp19a1, Stra8, and Cyp26b1 were downregulated in embryonic gonads. The results indicated that Rxrγ participated in gonadal differentiation and development in P. sinensis.

Voltage-gated sodium channel inhibitor reduces atherosclerosis by modulating monocyte/macrophage subsets and suppressing macrophage proliferation.

Inflammatory monocyte and macrophage subset accumulation during the inflammatory response that drives atherosclerosis can exacerbate the extent of atherosclerosis. It has been demonstrated that voltage-gated sodium channels (VGSCs) can regulate cell bioactivities in monocytes/macrophages. We hypothesized that blockade of mononuclear phagocyte VGSCs was atheroprotective through monocyte/macrophage subset modulation and macrophage proliferation suppression in atherosclerotic lesions. In this experimental study, when VGSCs were knocked down with RNA interference plasmid transfection in mouse peripheral blood monocytes and monocyte-macrophage lineage RAW264.7 cells in vitro, the biological characteristics of proliferation, phagocytosis, and migration in RAW264.7 cells declined. In addition, suppression of LPS-induced M1 polarization and facilitation of IL-4-induced M2 polarization were also observed. In an in vivo study, ApoE knockout (ApoE-/-) mice were fed a standard chow diet (CD) or a western diet (WD). After feeding with phenytoin (PHT), no significant differences were detected in plasma lipids, and the anti-inflammatory phenotypes of both monocytes and macrophages were elevated and proinflammatory phenotypes declined. The local proliferation of macrophages was also distinctly suppressed, along with a significant reduction in atheromatous plaques. In conclusion, blockade of VGSCs in the mononuclear phagocyte system reduced atherosclerotic lesions, which may occur through altering monocyte/macrophage subsets and suppressing macrophage proliferation in atherosclerotic plaques. Blockage of VGSCs may play an important role in cardiovascular protection.

Discordance Between VASP Phosphorylation and Platelet Aggregation in Defining High On-Clopidogrel Platelet Reactivity After ST-Segment Elevation Myocardial Infarction.

To investigate potential clinical characteristics associated with discordance between platelet vasodilator-stimulated phosphoprotein phosphorylation (VASP-P) flow cytometry (FCM) assay and light transmission aggregometry (LTA) in defining high on-clopidogrel platelet reactivity (HPR) after ST-segment elevation myocardial infarction (STEMI). In this study, platelet responsiveness was measured by the above 2 methods simultaneously on day 1 and on day 6 of STEMI onset in 90 consecutive patients who underwent primary percutaneous coronary intervention. The FCM-derived platelet reactivity index and LTA-derived platelet aggregation rate were both significantly reduced after dual antiplatelet therapy on day 6. Multiple variable-adjusted logistic regression analysis revealed that smoking (odds ratio [OR]: 4.507, 95% confidence interval [CI]: 1.123-18.09, P = .034) and onset-to-admission time (per 1 hour increase, OR: 1.196, 95% CI: 1.023-1.398, P = .025) both were independent predictors for the discordance between the 2 methods. Additionally, improved correlation and concordance was observed in nonsmokers compared with smokers. Our data show that smoking and prolonged onset-to-admission time are associated with discordance between platelet VASP-P and LTA in defining HPR after STEMI, which should be considered when planning personalized antiplatelet therapy.

The influence of different anticoagulants and time-delayed sample processing and measurements on human monocyte subset and monocyte-platelet aggregate analyses.

BACKGROUND: Measuring human monocyte subsets (CD14++CD16-, CD14++CD16+, and CD14 + CD16++) and subset-specific monocyte-platelet aggregates (MPA) is vulnerable to analytical bias due to unavailability of a standardized methodology. We aimed to address this issue by focusing on the impacts of time-delayed sample processing and measurement between two commonly used anticoagulants. METHODS: Ethylenediaminetetraacetic acid (EDTA)- and sodium citrate (SC)-anticoagulated blood samples from 12 healthy donors were subject to either delayed (2-h delay, kept at 4°C) or immediate processing (without fixation) before four-color flow cytometry (FCM) analysis. RESULTS: In SC-anticoagulated samples, a 2-h delay in sample processing contributed to a significant decrease in CD14++CD16- monocyte percent and a reciprocal increase in CD14++CD16+ monocytes, as well as increases in all three subset-specific MPA. Similar slight, but non-significant changes were observed in EDTA-treated samples. In samples processed immediately and stored at 4°C, delayed measurement at 0, 1, 3, and 5 h after processing led to a time-dependent decrease in CD14++CD16- monocyte percent and a reciprocal increase in CD14++CD16+ subset in SC-treated, but not in EDTA-treated, samples. Moreover, a time-dependent increase in all three subset-specific MPA was observed in SC-treated samples, which, to a lesser extent, was only observed in CD14++CD16+ MPA in EDTA-treated samples after storage at 4°C for 3-5 h after processing. CONCLUSIONS: We recommend EDTA for anticoagulation. Additionally, sample should be stored at 4°C and processing and measuring should be performed within 2 h after harvest and 3 h after processing, respectively. © 2016 International Clinical Cytometry Society.

Neutrophil extracellular traps in ischemia-reperfusion injury-induced myocardial no-reflow: therapeutic potential of DNase-based reperfusion strategy.

Emerging evidence suggests a potential role of neutrophil extracellular traps (NETs) in linking sterile inflammation and thrombosis. We hypothesized that NETs would be induced during myocardial ischemia-reperfusion (I/R), and NET-mediated microthrombosis may contribute to myocardial "no-reflow". Male Wistar rats were randomly divided into I/R control, DNase (DNase I, 20 µg/rat), recombinant tissue-type plasminogen activator (rt-PA, 420 µg/rat), DNase + rt-PA, and sham control groups after 45-min myocardial ischemia. In situ NET formation, the anatomic "no re-flow" area, and infarct size were evaluated immediately after 3 h of reperfusion. Long-term left ventricular (LV) functional and histological analyses were performed 45 days after operation. Compared with the I/R controls, the DNase + rt-PA group exhibited reduced NET density [8.38 ± 1.98 vs. 26.86 ± 3.07 (per 200 × field), P < 0.001] and "no-flow" area (15.22 ± 0.06 vs. 34.6 ± 0.05%, P < 0.05) in the ischemic region, as well as reduced infarct size (38.39 ± 0.05 vs. 71.00 ± 0.03%, P < 0.001). Additionally, compared with the I/R controls, DNase + rt-PA treatment significantly ameliorated I/R injury-induced LV remodeling (LV ejection fraction: 64.22 ± 3.37 vs. 33.81 ± 2.98%, P < 0.05; LV maximal slope of the LV systolic pressure increment: 3,785 ± 216 vs. 2,596 ± 299 mmHg/s, P < 0.05). The beneficial effect was not observed in rats treated with DNase I or rt-PA alone. Our study provides evidence for the existence of NETs in I/R-challenged myocardium and confirms the long-term benefit of a novel DNase-based reperfusion strategy (DNase I + rt-PA), which might be a promising option for the treatment of myocardial I/R injury and coronary no-reflow.

Monocyte subsets and monocyte-platelet aggregates in patients with unstable angina.

Monocyte subsets and monocyte-platelet aggregates (MPAs) play important role in atherosclerosis and thrombosis. We aimed to determine their changes in patients with unstable angina (UA). In this cross-sectional case-control study, Global Registry of Acute Coronary Events (GRACE) score was determined in 95 UA patients without elevated troponin level. Thirty age-and-sex matched stable coronary heart disease (CHD) subjects served as control group. The classical (CD14++CD16-, Mon1), the intermediate (CD14++CD16+, Mon2) and the non-classical (CD14+CD16++, Mon3) monocytes, as well as subset-specific MPAs, were measured by flow cytometry. Compared with stable CHD patients, UA patients had increased Mon2 and Mon3 counts (all P < 0.001). For UA subjects, compared with GRACE score-determined low risk patients (GRACE score ≤108, n = 70), intermediate-to-high risk patients (GRACE score >108, n = 25) had higher counts of Mon2 and total MPAs, as well as Mon1- and Mon2-associated MPAs (all P < 0.001). Adjusted binary logistic regression analysis revealed that increased counts of Mon2 subset (for per 5 cells/µL increase, OR 1.186, 95% CI 1.044-1.347, P = 0.009), Mon2 MPAs (for per 5 cells/µL increase, OR 1.228, 95% CI 1.062-1.421, P = 0.006) and total MPAs (for per 5 cells/µL increase, OR 1.072, 95 % CI 1.010-1.137, P = 0.022) independently associated with GRACE score-determined intermediate-to-high risk UA patients. In UA patients with intermediate-to-high risk (determined by GRACE score), counts of Mon2 subset, Mon2-associated MPAs and total MPAs are increased, which are independent of traditional risk factors.

High-salt intake induced visceral adipose tissue hypoxia and its association with circulating monocyte subsets in humans.

OBJECTIVE: To investigate the feasibility of blood oxygen level dependent magnetic resonance imaging (BOLD-MRI) in evaluating human visceral adipose tissue (AT) oxygenation induced by salt loading/depletion and its association with changes in circulating monocyte subsets. METHODS: A dietary intervention study was performed in 23 healthy volunteers beginning with a 3-day usual diet followed by a 7-day high-salt diet (≥15 g NaCl/day) and a 7-day low-salt diet (≤5 g NaCl/day). BOLD-MRI was used to evaluate oxygenation in perirenal AT. RESULTS: Salt loading led to a consistent AT hypoxia (increase in the R2* signal, 25.2 ± 0.90 s(-1) vs. baseline 21.5 ± 0.71 s(-1) , P < 0.001) and suppression of circulating renin-angiotensin-aldosterone system (RAAS), as well as an expansion of the CD14++CD16+ monocytes and monocyte pro-inflammatory activation. In salt depletion phase, the hypoxic state of AT and the expanded CD14++CD16+ monocyte pool were regressed to baseline levels, accompanied by a rebound activation of RAAS. Moreover, AT oxygenation level was positively correlated with the CD14++CD16+ monocytes (r = 0.419, P < 0.001). CONCLUSIONS: This work provides proof-of-principle evidence supporting the feasibility of BOLD-MRI in monitoring visceral AT oxygenation in humans induced by dietary salt loading/depletion. In addition, the CD14++CD16+ monocytes may participate in the pathogenesis of high-salt intake induced AT hypoxia.

[Dynamic changes of peripheral blood monocyte subsets after myocardial ischemia/reperfusion in rats].

OBJECTIVE: To investigate the dynamic changes of monocyte subsets after myocardial ischemia/reperfusion (I/R) in rats and their correlations with myocardial repair after I/R injury. METHODS: Sixteen male Wistar rats were randomly divided into two groups: I/R group and sham group. Myocardial I/R was induced by left anterior descending coronary artery ligation for 45 min followed by permanent reperfusion. Peripheral blood was harvested from the tail vein to evaluate the dynamics of CD172a(+);CD43(low); and CD172a(+);CD43(high); monocyte subsets by flow cytometry at baseline and on day 1, 3, 5, 7 and 14 after I/R injury. Survival rats were sacrificed on day 30, and the hearts were prepared for the evaluation of collagen deposition (Masson's trichrome staining) and myocardial hypertrophy (wheat-germ agglutinin staining). RESULTS: In I/R group, there was a significant increase of CD172a(+);CD43(low); monocytes on day 1 compared with the baseline (P<0.05), followed by an increasing trend, which peaked on day 3 (P<0.01), and then underwent a gradual decreasing trend to the baseline on day 7. In sham group, a similar increasing trend of CD172a(+);CD43(low); monocytes was observed on day 1 (P<0.05) compared with the baseline, whereas this trend declined rapidly to the baseline level on day 3. The proportion of CD172a(+);CD43(low); in I/R group on day 3 was much higher than that in the sham group (P<0.01). There were no significant differences between the two groups at any other time points. A reciprocal change of CD172a(+);CD43(high); monocytes was observed during investigation. Cardiac pathological evaluation revealed that there was a significant reparative fibrosis in the infarct area (P<0.05) along with a significant myocardial hypertrophy in non-infarct area (P<0.01) in I/R group. Correlation analysis showed that the proportion of CD172a(+);CD43(low); monocytes on day 3, but not CD172a(+);CD43(high); monocytes, was positively correlated with the level of collagen deposition in the infarct area (r=0.86, P<0.05). CONCLUSION: The study demonstrates the dynamic profile of circulating monocyte subsets following myocardial I/R injury in rats, which indicates that the proinflammatory CD172a(+);CD43(low); monocytes might be a therapeutic target to attenuate myocardial I/R injury.

Decreased circulating microRNA-223 level predicts high on-treatment platelet reactivity in patients with troponin-negative non-ST elevation acute coronary syndrome.

To investigate the relationship between circulating microRNA 223 (miR-223) levels and clopidogrel responsiveness in patients with coronary heart disease. A total of 62 consecutive patients with troponin-negative non-ST elevation acute coronary syndrome (NSTE-ACS) scheduled for elective percutaneous coronary intervention were enrolled. The plasma circulating miR-223 levels were quantified by real-time PCR, and platelet reactivity was determined by platelet reactivity index (PRI), measured by vasodilator-stimulated phosphoprotein (VASP) phosphorylation flow cytometry after 300 mg (for at least 24 h) or 75 mg clopidogel (for at least 5 days) plus aspirin treatment. All subjects were dichotomized according to PRI median (normal-responders: PRI ≤ 56.3%, n = 31 and low-responders: PRI > 56.3%, n = 31). Compared with normal-responders, circulating miR-223 level was significantly decreased in low-responders (P = 0.007). In addition, miR-223 level was statistically correlated with PRI (Spearman r = -0.379, P = 0.002). Stepwise binary logistic regression analysis revealed that among factors that potentially influence platelet reactivity (CYP2C19*2/*3 loss-of-function genotypes, use of calcium channel blockers/proton-pump inhibitors, age, diabetes and smoking), decreased circulating miR-223 level was the only independent predictor for the presence of PRI-determined lower responders (OR 0.111, 95% CI 0.018-0.692, P = 0.019). Our data suggest that circulating miR-223 may serve as a novel biomarker for assessment of clopidogrel responsiveness in troponin-negative NSTE-ACS patients.

Temporal and spatial characterization of mononuclear phagocytes in circulating, lung alveolar and interstitial compartments in a mouse model of bleomycin-induced pulmonary injury.

The mononuclear phagocyte system, including circulating monocytes and tissue resident macrophages, plays an important role in acute lung injury and fibrosis. The detailed dynamic changes of mononuclear phagocytes in the circulating, lung alveolar and interstitial compartments in bleomycin-induced pulmonary injury model have not been fully characterized. The present study was designed to address this issue and analyzed their relationships with pulmonary pathological evolution after bleomycin challenge. A total of 100 male C57BL/6 mice were randomly divided to receive bleomycin (2.5mg/kg, n=50) or normal saline (n=50) via oropharyngeal approach, and were sacrificed on days 1, 3, 7, 14 and 21. Circulating monocyte subsets, polarization state of bronchoalveolar lavage fluid (BALF)-derived alveolar macrophages (AMφ) and lung interstitial macrophages (IMφ, derived from enzymatically digested lung tissue) were analyzed by flow cytometry. There was a rapid expansion of circulating Ly6C(hi) monocytes which peaked on day 3, and its magnitude was positively associated with pulmonary inflammatory response. Moreover, an expansion of M2-like AMφ (F4/80+CD11c+CD206+) peaked on day 14, and was positively correlated with the magnitude of lung fibrosis. The polarization state of IMφ remained relatively stable in the early- and mid-stage after bleomycin challenge, expect for an increase of M2-like (F4/80+CD11c-CD206+) IMφ on day 21. These results support the notion that there is a Ly6C(hi)-monocyte-directed pulmonary AMφ alternative activation. Our result provides a dynamic view of mononuclear phagocyte change in three compartments after bleomycin challenge, which is relevant for designing new treatment strategies targeting mononuclear phagocytes in this model.

Spironolactone attenuates bleomycin-induced pulmonary injury partially via modulating mononuclear phagocyte phenotype switching in circulating and alveolar compartments.

BACKGROUND: Recent experimental studies provide evidence indicating that manipulation of the mononuclear phagocyte phenotype could be a feasible approach to alter the severity and persistence of pulmonary injury and fibrosis. Mineralocorticoid receptor (MR) has been reported as a target to regulate macrophage polarization. The present work was designed to investigate the therapeutic potential of MR antagonism in bleomycin-induced acute lung injury and fibrosis. METHODOLOGY/PRINCIPAL FINDINGS: We first demonstrated the expression of MR in magnetic bead-purified Ly6G-/CD11b+ circulating monocytes and in alveolar macrophages harvested in bronchoalveolar lavage fluid (BALF) from C57BL/6 mice. Then, a pharmacological intervention study using spironolactone (20 mg/kg/day by oral gavage) revealed that MR antagonism led to decreased inflammatory cell infiltration, cytokine production (downregulated monocyte chemoattractant protein-1, transforming growth factor ß1, and interleukin-1ß at mRNA and protein levels) and collagen deposition (decreased lung total hydroxyproline content and collagen positive area by Masson' trichrome staining) in bleomycin treated (2.5 mg/kg, via oropharyngeal instillation) male C57BL/6 mice. Moreover, serial flow cytometry analysis in blood, BALF and enzymatically digested lung tissue, revealed that spironolactone could partially inhibit bleomycin-induced circulating Ly6C(hi) monocyte expansion, and reduce alternative activation (F4/80+CD11c+CD206+) of mononuclear phagocyte in alveoli, whereas the phenotype of interstitial macrophage (F4/80+CD11c-) remained unaffected by spironolactone during investigation. CONCLUSIONS/SIGNIFICANCE: The present work provides the experimental evidence that spironolactone could attenuate bleomycin-induced acute pulmonary injury and fibrosis, partially via inhibition of MR-mediated circulating monocyte and alveolar macrophage phenotype switching.

Modulation of mononuclear phagocyte inflammatory response by liposome-encapsulated voltage gated sodium channel inhibitor ameliorates myocardial ischemia/reperfusion injury in rats.

BACKGROUND: Emerging evidence shows that anti-inflammatory strategies targeting inflammatory monocyte subset could reduce excessive inflammation and improve cardiovascular outcomes. Functional expression of voltage-gated sodium channels (VGSCs) have been demonstrated in monocytes and macrophages. We hypothesized that mononuclear phagocyte VGSCs are a target for monocyte/macrophage phenotypic switch, and liposome mediated inhibition of mononuclear phagocyte VGSC may attenuate myocardial ischemia/reperfusion (I/R) injury and improve post-infarction left ventricular remodeling. METHODOLOGY/PRINCIPAL FINDINGS: Thin film dispersion method was used to prepare phenytoin (PHT, a non-selective VGSC inhibitor) entrapped liposomes. Pharmacokinetic study revealed that the distribution and elimination half-life of PHT entrapped liposomes were shorter than those of free PHT, indicating a rapid uptake by mononuclear phagocytes after intravenous injection. In rat peritoneal macrophages, several VGSC α subunits (NaV1.1, NaV1.3, NaV1.4, NaV1.5, NaV1.6, NaV1.7, NaVX, Scn1b, Scn3b and Scn4b) and ß subunits were expressed at mRNA level, and PHT could suppress lipopolysaccharide induced M1 polarization (decreased TNF-α and CCL5 expression) and facilitate interleukin-4 induced M2 polarization (increased Arg1 and TGF-ß1 expression). In vivo study using rat model of myocardial I/R injury, demonstrated that PHT entrapped liposome could partially suppress I/R injury induced CD43+ inflammatory monocyte expansion, along with decreased infarct size and left ventricular fibrosis. Transthoracic echocardiography and invasive hemodynamic analysis revealed that PHT entrapped liposome treatment could attenuate left ventricular structural and functional remodeling, as shown by increased ejection fraction, reduced end-systolic and end-diastolic volume, as well as an amelioration of left ventricular systolic (+dP/dt max) and diastolic (-dP/dt min) functions. CONCLUSIONS/SIGNIFICANCE: Our work for the first time demonstrates the therapeutic potential of VGSC antagonism via liposome mediated monocyte/macrophage targeting in acute phase after myocardial I/R injury. These results suggest that VGSCs in mononuclear phagocyte system might be a novel target for immunomodulation and treatment of myocardial I/R injury.

[Inhibitory effect of NaV1.9 gene silencing on proliferation, phagocytosis and migration in RAW264.7 cells].

OBJECTIVE: To establish the cell line with stable voltage-gated sodium channels (VGSCs/NaVs) α subunit NaV1.9 gene silencing through RNA interference (RNAi) in murine RAW264.7 macrophages, and to investigate proliferation, phagocytosis and migration in this cell line. METHODS: The stable NaV1.9-deficient cell line was generated by selection in G418 after the transfection of short hairpin (shRNA) plasmid with Lipofectamine TM2000. RNAi efficiency was qualified by RT-PCR; proliferation ability was measured by CCK-8 assay; cell cycle and phagocytic ability were analyzed by flow cytometry; and migrating ability was detected by Transwell migration assay. RESULTS: Stable NaV1.9-deficient cell line was established and the expression of NaV1.9 was reduced by 80%. CCK-8 assay and flow cytometry showed that the proliferation of the NaV1.9-deficient cell line was inhibited (P<0.05). Flow cytometry revealed that phagocytic ability was reduced in the cell line (P<0.05). Transwell migration assay demonstrated that migrating ability was depressed in the cell line (P<0.05). CONCLUSION: In the stable NaV1.9-deficient cells we successfully constructed, proliferation, phagocytosis and migration were obviously inhibited.

[Effect of Kruppel like factor 4 gene silencing on apoptosis and phagocytosis of murine RAW264.7 macrophages].

OBJECTIVE: To investigate the effect of down-regulation of Kruppel like factor 4 (KLF4) by RNA interference on proliferation, apoptosis and phagocytosis in murine RAW264.7 macrophage cell line. METHODS: Stable KLF4 silencing in RAW264.7 cells was achieved by recombinant shRNA plasmid targeting murine KLF4 gene via liposome mediated transfection, followed by G418 selection. The efficacy of KLF4 silencing in G418 resistant cells was verified by fluorescent microcopy and Western blotting, respectively. Proliferative activity was analyzed by CCK-8 assay. Apoptosis and phagocytosis were evaluated by annexinV-FITC/PI staining and flow cytometry with assistant use of fluorescein-labeled E.coli K-12 particles, respectively. RESULTS: KLF4 protein expression was significantly down-regulated by the recombinant shRNA plasmid as compared with negative control (NC) plasmid transfection, inhibition rate being over 76%. From the third day, KLF4-silencing cells exhibited lower proliferative activity as compared with NC RAW264.7 cells (P<0.05). In resting state, apoptosis rate in wide type, NC and KLF4-silencing cells were 1.73%, 6.85% and 12.76%, respectively, and KLF4-silencing resulted in a statistical difference in apoptosis as compared with NC cells (P<0.05). Finally, phagocytic capability in wide type, NC and KLF4-silencing cells revealed by the mean fluorescence intensity of engulfed FITC-labeled E.coli particles were 122.0 ± 2.80, 48.97 ± 5.69 and 80.10 ± 4.61, respectively, and compared with NC cells, KLF4-silencing cells had a significant increase in phagocytosis (P<0.05). CONCLUSION: KLF4 gene silencing inhibits RAW264.7 macrophage proliferation, increase apoptosis and enhance phagocytic function in resting state, which provides a novel tool for revealing the role of KLF4 in macrophage immunity.

Decreased platelet miR-223 expression is associated with high on-clopidogrel platelet reactivity.

OBJECTIVES: We aimed to investigate the relationship between platelet microRNA (miR-223 and miR-96) expression and clopidogrel responsiveness in patients with coronary heart disease (CHD). MATERIALS AND METHODS: A total of 33 consecutive non-diabetic CHD patients scheduled for percutaneous coronary intervention were enrolled. Platelet reactivity after clopidogrel loading dose (300 mg) was determined by two methods [platelet reactivity index (PRI), measured by vasodilator-stimulated phosphoprotein (VASP) phosphorylation flow cytometry and ADP-induced platelet aggregation (PAG), measured by light transmission aggregometry]. Total platelet RNA was isolated from purified platelets (CD45 magnetic bead negative selection) to quantify miR-223 and miR-96 expression by real-time PCR. RESULTS: All subjects were dichotomized according to PRI medians (normal-responders: PRI < 56.5%, n = 17 and low-responders: PRI > 56.5%, n = 16) and PAG medians (normal-responders: PAG < 43%, n = 17 and low-responders: PAG > 43%, n = 16). Compared with PRI-determined normal-responders, miR-223 expression, but not miR-96, was significantly decreased in low-responders (P = 0.037). No differential expression of miR-223 and miR-96 was observed via PAG determination between normal- and low-responders. In addition, miR-223 expression, but not miR96, was statistically correlated with PRI (Spearman r = -0.403, P = 0.020). Stepwise binary logistic regression analysis revealed that among factors that potentially influence platelet reactivity (CYP2C19*2 loss-of-function genotypes, use of calcium channel blockers/proton-pump inhibitors, age, obesity, smoking and platelet microRNAs), decreased miR-223 expression was the only independent predictor associated with the presence of PRI-determined low responders to clopidogrel (OR 0.189, 95% CI 0.043 to 0.836, P = 0.028). CONCLUSIONS: The present work identifies decreased platelet miR-223 expression as a novel mechanism involved in blunted platelet response to clopidogrel in a Chinese population.