Shear Forces Induced Platelet Clearance Is a New Mechanism of Thrombocytopenia.

BACKGROUND: Thrombocytopenia has been consistently described in patients with extracorporeal membrane oxygenation (ECMO) and associated with poor outcome. However, the prevalence and underlying mechanisms remain largely unknown, and a device-related role of ECMO in thrombocytopenia has been hypothesized. This study aims to investigate the mechanisms underlying thrombocytopenia in ECMO patients. METHODS: In a prospective cohort of 107 ECMO patients, we investigated platelet count, functions, and glycoprotein shedding. In an ex vivo mock circulatory ECMO loop, we assessed platelet responses and VWF (von Willebrand factor)-GP Ibα (glycoprotein Ibα) interactions at low- and high-flow rates, in the presence or absence of red blood cells. The clearance of human platelets subjected or not to ex vivo perfusion was studied using an in vivo transfusion model in NOD/SCID (nonobese diabetic/severe combined Immunodeficient) mice. RESULTS: In ECMO patients, we observed a time-dependent decrease in platelet count starting 1 hour after device onset, with a mean drop of 7%, 35%, and 41% at 1, 24, and 48 hours post-ECMO initiation (P=0.00013, P<0.0001, and P<0.0001, respectively), regardless of the type of ECMO. This drop in platelet count was associated with a decrease in platelet GP Ibα expression (before: 47.8±9.1 versus 24 hours post-ECMO: 42.3±8.9 mean fluorescence intensity; P=0.002) and an increase in soluble GP Ibα plasma levels (before: 5.6±3.3 versus 24 hours post-ECMO: 10.8±4.1 µg/mL; P<0.0001). GP Ibα shedding was also observed ex vivo and was unaffected by (1) red blood cells, (2) the coagulation potential, (3) an antibody blocking VWF-GP Ibα interaction, (4) an antibody limiting VWF degradation, and (5) supraphysiological VWF plasma concentrations. In contrast, GP Ibα shedding was dependent on rheological conditions, with a 2.8-fold increase at high- versus low-flow rates. Platelets perfused at high-flow rates before being transfused to immunodeficient mice were eliminated faster in vivo with an accelerated clearance of GP Ibα-negative versus GP Ibα-positive platelets. CONCLUSIONS: ECMO-associated shear forces induce GP Ibα shedding and thrombocytopenia due to faster clearance of GP Ibα-negative platelets. Inhibiting GP Ibα shedding could represent an approach to reduce thrombocytopenia during ECMO.

The unexpected increase of clotrimazole apparent solubility using randomly methylated ß-cyclodextrin.

Clotrimazole (CTZ) and cyclodextrin (CD) inclusion complexes having improved apparent water solubility were obtained from phase solubility diagrams. ß-CD (1.5% w/w) and hydroxypropyl-ß-CD (40% w/w) offered poor CTZ solubility enhancements (12 and 384 times, respectively). Unexpectedly, the apparent solubility of CTZ was 9980 times increased from 0.4 µg.mL(-1) (1.42 µM) without CD to 4.89 mg.mL(-1) (14.9 mM) using randomly-methylated ß-CD (Me-ß-CD) (40% w/w). This is the highest apparent CTZ solubility improvement ever reported in the literature using conventional CDs. Quantitative nuclear magnetic resonance ((1) H-NMR) coupled with two-dimensional nuclear Overhauser effect (NOESY) experiments and molecular docking calculations showed that the highest interactions with Me-ß-CD were reported for CTZ two phenyl groups. A lower interaction was reported for chlorophenyl, while imidazole had the weakest interaction with Me-ß-CD.

Drug-free chitosan coated poly(isobutylcyanoacrylate) nanoparticles are active against trichomonas vaginalis and non-toxic towards pig vaginal mucosa.

PURPOSE: The present work reports a non-conventional therapeutic strategy based on the use of vaginally-applied formulations for the treatment of trichomoniasis due to Trichomonas vaginalis without adding a drug. METHODS: The formulations were based on a thermosensitive pluronic® F127 hydrogel containing mucoadhesive poly(isobutylcyanoacrylate) nanoparticles coated with a mixture of chitosan and thiolated chitosan (75/25 wt%). The nanoparticles were obtained by anionic emulsion polymerization of isobutylcyanoacrylate. The anti-T. vaginalis activity of the formulations was evaluated in vitro. RESULTS: Chitosan-coated nanoparticles showed a strong anti-T. vaginalis activity at 100 µg/mL independently on the proportion of thiolated chitosan. No anti-T. vaginalis activity was reported neither with chitosan-uncoated poly(isobutylcyanoacrylate) nanoparticles nor with chitosan used as a solution. These results suggest that the anti-T. vaginalis activity was related to poly(isobutylcyanoacrylate) nanoparticles but only when they are coated with chitosan. Histological analysis of ex vivo pig vaginal mucosa in contact with pluronic® F127 hydrogel containing poly(isobutylcyanoacrylate) nanoparticles coated with the mixture chitosan/thiolated chitosan (75/25 wt%) did not reveal any toxicity. CONCLUSION: This study demonstrated that poly(isobutylcyanoacrylate) nanoparticles coated with chitosan were active against T. vaginalis without adding a drug. Besides their anti-T. vaginalis activity, the formulations are non-toxic towards pig vaginal mucosa.

Adherent Bacteria and Parasiticidal Secretion Products of Human Cervicovaginal Microbiota-Associated Lactobacillus gasseri Confer Non-Identical Cell Protection against Trichomonas vaginalis-Induced Cell Detachment.

Trichomonas vaginalis, a protozoan parasite specific to the human genital tract, is one of the most common sexually transmitted pathogens. Its pathogenicity is strongly associated with its expression of a broad array of proteases triggering cytotoxic effects in host epithelial cells. Vaginal microbiota-associated Lactobacillus, including those of L. gasseri in particular, can counteract T. vaginalis pathogenesis, but the mechanisms involved have yet to be clarified. T. vaginalis strain G3 (Tv G3) cytotoxicity was assessed by examining cell morphology, cell detachment, and fluorescent labeling of the F-actin cytoskeleton and immunolabeling of vinculin-position focal adhesions (FAs) by confocal laser scanning electron microscopy on confluent cervicovaginal epithelial HeLa cell monolayers. The inhibitory effects of bacterial cells and secreted products of L. gasseri ATCC 9857 and KS 120.1 on the Tv G3 viability and parasite deleterious effects on HeLa cells were investigated. Pre-adhering L. gasseri cells delayed but did not inhibit Tv G3-induced cell detachment, F-actin cytoskeleton disorganization and the disappearance of vinculin-positive focal FAs. L. gasseri KS 120.1 secretion products had a rapid parasiticide activity by killing time- and concentration-dependent Tv G3 parasites after direct contact. By killing Tv G3 parasites already associated with the epithelial cells, secretion products have abolished parasite-induced cell detachment. Our findings suggest that vagina microbiota-associated L. gasseri creates a physical barrier and exerts pharmacological-type mechanisms to counteract the deleterious cytotoxic effects of T. vaginalis.

Thrombus formation during ECMO: Insights from a detailed histological analysis of thrombus composition.

OBJECTIVES: Intra-device thrombosis remains one of the most common complications during extracorporeal membrane oxygenation (ECMO). Despite anticoagulation, approximately 35% of patients develop thrombi in the membrane oxygenator, pump heads, or tubing. The aim of this study was to describe the molecular and cellular features of ECMO thrombi and to study the main drivers of thrombus formation at different sites in the ECMO circuits. APPROACH AND RESULTS: Thrombi (n = 85) were collected immediately after veno-arterial-(VA)-ECMO circuit removal from 25 patients: 23 thrombi from the pump, 25 from the oxygenator, and 37 from the tubing. Quantitative histological analysis was performed for the amount of red blood cells (RBCs), platelets, fibrin, von Willebrand factor (VWF), leukocytes, and citrullinated histone H3 (H3Cit). ECMO thrombi consist of a heterogenous composition with fibrin and VWF being the major thrombus components. A clustering analysis of the four major histological parameters identified two typical thrombus types: RBC-rich and RBC-poor/fibrin-rich thrombi with no significant differences in VWF and platelet content. Thrombus composition was not associated with the thrombus location, except for higher amounts of H3Cit that were found in pump and oxygenator thrombi compared to tubing samples. We observed higher blood leukocyte count and lactate dehydrogenase levels in patients with fibrin-rich thrombi. CONCLUSION: We found that thrombus composition is heterogenous, independent of their location, consisting of two types: RBC-rich and a fibrin-rich types. We also found that NETs play a minor role. These findings are important to improve current anticoagulation strategies in ECMO.

Gastrointestinal bleeding from angiodysplasia in von Willebrand disease: Improved diagnosis and outcome prediction using videocapsule on top of conventional endoscopy.

BACKGROUND: Despite a high prevalence of angiodysplasia, no specific guidelines are available for the modalities of endoscopic exploration of gastrointestinal (GI) bleeding in von Willebrand disease (VWD). Whether VWD patients could benefit from video capsule endoscopy (VCE) looking for angiodysplasia eligible to endoscopic treatment or at high risk of bleeding is unknown. OBJECTIVES: To assess the diagnostic efficacy for angiodysplasia and the prognostic value of VCE on top of conventional endoscopy in VWD patients with GI bleeding. PATIENTS/METHODS: A survey was sent to the 30 centers of the French-network on inherited bleeding disorders to identify VWD patients referred for endoscopic exploration of GI bleeding from January 2015 to December 2017. Data obtained included patient characteristics, VWD phenotype/genotype, GI bleeding pattern, results of endoscopic investigations, and medical management applied including endoscopic therapy. We assessed by Kaplan-Meier analysis the recurrence-free survival after the first GI bleeding event according to endoscopic categorization and, in patients with angiodysplasia, to the presence of small-bowel localizations on VCE exploration. RESULTS: GI bleeding source localization was significantly improved when including VCE exploration (P < .01), even in patients without history of angiodysplasia (P < .05). Patients with angiodysplasia had more GI bleeding recurrences (P < .01). A lower recurrence-free survival was observed in patients with angiodysplasia (log-rank test, P = .02), and especially when lesions were located in the small bowel (log-rank test, P < .01), even after endoscopic treatment with argon plasma coagulation (log-rank test, P < .01). CONCLUSION: VCE should be more systematically used in VWD patients with unexplained or recurrent GI bleeding looking for angiodysplasia eligible to endoscopic treatment or at high risk of relapse.

In situ forming pluronic® F127/chitosan hydrogel limits metronidazole transmucosal absorption.

The objective of this work is to design topically-applied thermosensitive and mucoadhesive hydrogel containing metronidazole (MTZ) for the treatment of Trichomonas vaginalis infections. Hydrogel composed of pluronic® F127 (20wt%), chitosan (1wt%) and metronidazole MTZ (0.7wt%) mixture showed its ability to decrease by a factor 4 MTZ flux and apparent permeability absorption through vaginal mucosa. The impact of hydrogel on transmucosal penetration of MTZ was evaluated ex vivo on excised porcine vaginal mucosa mounted on Franz diffusion cell. The anti-T. vaginalis activity of MTZ formulated into F127/chitosan hydrogel was preserved since the viability curve evaluated in vitro was similar to MTZ solution.

Gelation and micellization behaviors of pluronic(®) F127 hydrogel containing poly(isobutylcyanoacrylate) nanoparticles specifically designed for mucosal application.

The aim of this investigation is to combine the advantages of pluronic(®) F127 hydrogels and nanoparticles composed of poly(isobutylcyanoacrylate) (PIBCA) core coated with a mixture of chitosan and thiolated chitosan to design novel multifunctional formulation for mucosal application. Nanoparticles offer the advantage of being mucoadhesive while pluronic(®) F127 hydrogel allowed prolonged contact time onto mucosal surfaces. This work highlights an unprecedented comprehensive study on the effect of nanoparticles on gelation and micellization behaviors of pluronic(®) F127 using rheology and micro-calorimetry experiments. Results showed that presence of nanoparticles induced (i) smaller crystal peak of F127, (ii) a decrease of the enthalpy of F127 micellization and (iii) a non-reversibility of micelle formation (during heating ramp) and micelle melting (during cooling ramp). Together, these findings suggest that a part of F127 was not able to associate into micelles and the formation of mixed micelles containing F127 unimers and PIBCA/(chitosan/thiolated chitosan) copolymer and/or PIBCA homopolymer was suspected. The interaction of F127 unimers with nanoparticles resulted from their physical de-structuration as revealed by nanoparticle size measurement. In addition, we found that short polymerization duration of one hour induced more pronounced nanoparticle de-structuration. Twenty-four hour-polymerization of isobutylcyanoacrylate in the presence of chitosan and thiolated chitosan led to more stable nanoparticles when mixed with pluronic(®) F127.

Cell line-dependent cytotoxicity of poly(isobutylcyanoacrylate) nanoparticles coated with chitosan and thiolated chitosan: Insights from cultured human epithelial HeLa, Caco2/TC7 and HT-29/MTX cells.

Nanoparticles composed of poly(isobutylcyanoacrylate) core coated with a mixture of chitosan and thiolated chitosan have already shown promising results in terms of mucoadhesion and permeation enhancement properties of pharmaceutical active drugs delivered via mucosal routes. In the present work, the cytotoxicity of these nanoparticles was first investigated using direct contact assay on undifferentiated human cervix epithelial HeLa cells. The results showed strong toxicity in HeLa cells for the two investigated concentrations 25 and 50 µg/mL. The cytotoxic effect was mainly attributed to the poly(isobutylcyanoacrylate) core since no significant differences in nanoparticle cytotoxicity were reported when nanoparticle shell composition was modified by adding chitosan or thiolated chitosan. In contrast, lower nanoparticle toxicity was reported using human fully-differentiated enterocyte-like Caco-2/TC7, and fully-differentiated mucus-secreting HT-29/MTX cells forming monolayer in culture mimicking an intestinal epithelial barrier. This study demonstrated that the toxicity of poly(isobutylcyanoacrylate) nanoparticles is highly cell line-dependent.

Investigation of the complexation of albendazole with cyclodextrins for the design of new antiparasitic formulations.

Albendazole (ABZ) exhibits a potent antiparasitic activity against a broad spectrum of parasites. Unfortunately, the very low water solubility of ABZ (0.2 µg mL(-1), 0.7 µM) impairs considerably its formulation. Phase solubility diagrams showed that α-cyclodextrin (10% w/w), hydroxypropyl-ß-cyclodextrin (40% w/w) and sulfobutylether-ß-cyclodextrin (40% w/w) allowed an increase of apparent solubility with enhancement factors of 570, 3970, and 5880, respectively. The apparent aqueous solubility of ABZ was markedly increased from 0.2 µg mL(-1) (0.7 µM) without cyclodextrins to 1.52 mg mL(-1) (5.69 mM) with random methyl-ß-cyclodextrin (Me-ß-CD) (40% w/w). This corresponds to an apparent solubility enhancement factor of 7600 which is the maximal enhancement factor of ABZ apparent aqueous solubility ever reported in the literature using conventional cyclodextrins. The complexation mechanism between ABZ and cyclodextrins has been investigated using phase solubility diagrams, nuclear magnetic resonance ((1)H NMR) coupled with two-dimensional nuclear Overhauser effect (NOESY) experiments and molecular docking calculations. The results showed that the central bicyclic fragment from ABZ interacts with Me-ß-CD according to 1:1 stoichiometry.