White matter hyperintensity genetic risk factor TRIM47 regulates autophagy in brain endothelial cells.

White matter hyperintensity (WMH) is strongly correlated with age-related dementia and hypertension, but its pathogenesis remains obscure. GWAS identified TRIM47 at 17q25 locus as a top genetic risk factor for WMH formation. TRIM family is a class of E3 ubiquitin ligase with pivotal functions in autophagy, which is critical for brain endothelial cell (ECs) remodeling during hypertension. We hypothesize that TRIM47 regulates autophagy and its loss-of-function disturbs cerebrovasculature. Based on transcriptomics and immunohistochemistry, TRIM47 is found selectively expressed by brain ECs in human and mouse, and its transcription is upregulated by artificially-induced autophagy while downregulated in hypertension-like conditions. Using in silico simulation, immunocytochemistry and super-resolution microscopy, we identified the highly conserved binding site between TRIM47 and the LIR (LC3-interacting region) motif of LC3B. Importantly, pharmacological autophagy induction increased Trim47 expression on mouse ECs (b.End3) culture, while silencing Trim47 significantly increased autophagy with ULK1 phosphorylation induction, transcription and vacuole formation. Together, we confirm that TRIM47 is an endogenous inhibitor of autophagy in brain ECs, and such TRIM47-mediated regulation connects genetic and physiological risk factors for WMH formation but warrants further investigation. SUMMARY STATEMENT: TRIM47, top genetic risk factor for white matter hyperintensity formation, is a negative regulator of autophagy in brain endothelial cells and implicates a novel cellular mechanism for age-related cerebrovascular changes.

Cuprizone drives divergent neuropathological changes in different mouse models of Alzheimer's disease.

Myelin degradation is a normal feature of brain aging that accelerates in Alzheimer's disease (AD). To date, however, the underlying biological basis of this correlation remains elusive. The amyloid cascade hypothesis predicts that demyelination is caused by increased levels of the ß-amyloid (Aß) peptide. Here we report on work supporting the alternative hypothesis that early demyelination is upstream of amyloid. We challenged two different mouse models of AD (R1.40 and APP/PS1) using cuprizone-induced demyelination and tracked the responses with both neuroimaging and neuropathology. In oppose to amyloid cascade hypothesis, R1.40 mice, carrying only a single human mutant APP (Swedish; APP SWE ) transgene, showed a more abnormal changes of magnetization transfer ratio and diffusivity than in APP/PS1 mice, which carry both APP SWE and a second PSEN1 transgene (delta exon 9; PSEN1 dE9 ). Although cuprizone targets oligodendrocytes (OL), magnetic resonance spectroscopy and targeted RNA-seq data in R1.40 mice suggested a possible metabolic alternation in axons. In support of alternative hypotheses, cuprizone induced significant intraneuronal amyloid deposition in young APP/PS1, but not in R1.40 mice, and it suggested the presence of PSEN deficiencies, may accelerate Aß deposition upon demyelination. In APP/PS1, mature OL is highly vulnerable to cuprizone with significant DNA double strand breaks (53BP1 + ) formation. Despite these major changes in myelin, OLs, and Aß immunoreactivity, no cognitive impairment or hippocampal pathology was detected in APP/PS1 mice after cuprizone treatment. Together, our data supports the hypothesis that myelin loss can be the cause, but not the consequence, of AD pathology. SIGNIFICANCE STATEMENT: The causal relationship between early myelin loss and the progression of Alzheimer's disease remains unclear. Using two different AD mouse models, R1.40 and APP/PS1, our study supports the hypothesis that myelin abnormalities are upstream of amyloid production and deposition. We find that acute demyelination initiates intraneuronal amyloid deposition in the frontal cortex. Further, the loss of oligodendrocytes, coupled with the accelerated intraneuronal amyloid deposition, interferes with myelin tract diffusivity at a stage before any hippocampus pathology or cognitive impairments occur. We propose that myelin loss could be the cause, not the consequence, of amyloid pathology during the early stages of Alzheimer's disease.

Apolipoprotein E ε4 disrupts oligodendrocyte differentiation by interfering with astrocyte-derived lipid transport.

Carriers of the APOE4 (apolipoprotein E ε4) variant of the APOE gene are subject to several age-related health risks, including Alzheimer's disease (AD). The deficient lipid and cholesterol transport capabilities of the APOE4 protein are one reason for the altered risk profile. In particular, APOE4 carriers are at elevated risk for sporadic AD. While deposits o misfolded proteins are present in the AD brain, white matter (WM) myelin is also disturbed. As myelin is a lipid- and cholesterol-rich structure, the connection to APOE makes considerable biological sense. To explore the APOE-WM connection, we have analyzed the impact of human APOE4 on oligodendrocytes (OLs) of the mouse both in vivo and in vitro. We find that APOE proteins is enriched in astrocytes but sparse in OL. In human APOE4 (hAPOE4) knock-in mice, myelin lipid content is increased but the density of major myelin proteins (MBP, MAG, and PLP) is largely unchanged. We also find an unexpected but significant reduction of cell density of the OL lineage (Olig2+ ) and an abnormal accumulation of OL precursors (Nkx 2.2+ ), suggesting a disruption of OL differentiation. Gene ontology analysis of an existing RNA-seq dataset confirms a robust transcriptional response to the altered chemistry of the hAPOE4 mouse brain. In culture, the uptake of astrocyte-derived APOE during Lovastatin-mediated depletion of cholesterol synthesis is sufficient to sustain OL differentiation. While endogenous hAPOE protein isoforms have no effects on OL development, exogenous hAPOE4 abolishes the ability of very low-density lipoprotein to restore myelination in Apoe-deficient, cholesterol-depleted OL. Our data suggest that APOE4 impairs myelination in the aging brain by interrupting the delivery of astrocyte-derived lipids to the oligodendrocytes. We propose that high myelin turnover and OL exhaustion found in APOE4 carriers is a likely explanation for the APOE-dependent myelin phenotypes of the AD brain.

Machine learning-based scoring system to predict in-hospital outcomes in patients hospitalized with COVID-19.

BACKGROUND: The evolution of patients hospitalized with coronavirus disease 2019 (COVID-19) is still hard to predict, even after several months of dealing with the pandemic. AIMS: To develop and validate a score to predict outcomes in patients hospitalized with COVID-19. METHODS: All consecutive adults hospitalized for COVID-19 from February to April 2020 were included in a nationwide observational study. Primary composite outcome was transfer to an intensive care unit from an emergency department or conventional ward, or in-hospital death. A score that estimates the risk of experiencing the primary outcome was constructed from a derivation cohort using stacked LASSO (Least Absolute Shrinkage and Selection Operator), and was tested in a validation cohort. RESULTS: Among 2873 patients analysed (57.9% men; 66.6±17.0 years), the primary outcome occurred in 838 (29.2%) patients: 551 (19.2%) were transferred to an intensive care unit; and 287 (10.0%) died in-hospital without transfer to an intensive care unit. Using stacked LASSO, we identified 11 variables independently associated with the primary outcome in multivariable analysis in the derivation cohort (n=2313), including demographics (sex), triage vitals (body temperature, dyspnoea, respiratory rate, fraction of inspired oxygen, blood oxygen saturation) and biological variables (pH, platelets, C-reactive protein, aspartate aminotransferase, estimated glomerular filtration rate). The Critical COVID-19 France (CCF) risk score was then developed, and displayed accurate calibration and discrimination in the derivation cohort, with C-statistics of 0.78 (95% confidence interval 0.75-0.80). The CCF risk score performed significantly better (i.e. higher C-statistics) than the usual critical care risk scores. CONCLUSIONS: The CCF risk score was built using data collected routinely at hospital admission to predict outcomes in patients with COVID-19. This score holds promise to improve early triage of patients and allocation of healthcare resources.

Utilization of Generic Cardiovascular Drugs in Medicare's Part D Program.

BACKGROUND: Generic medications cost less than brand-name medications and are similarly effective, but brand-name medications are still prescribed. We evaluated patterns in generic cardiovascular medication fills and estimated the potential cost savings with increased substitution of generic for brand-name medications. METHODS: This was a cross-sectional study of cardiovascular therapies using the Medicare Part D database of prescription medications in 2017. We evaluated drug fill patterns for therapies with available brand-name and generic options. We determined the generic substitution ratio and estimated the potential savings with increased generic substitution at the national, state, and clinician level. We compared states with laws related to mandatory pharmacist generic substitution and patient consent for substitution. RESULTS: Of ≈$22.9 billion spent on cardiovascular drugs in Medicare Part D prescription programs in 2017, ≈$11.0 billion was spent on medications with both brand-name and generic options. Although only 2.4% of medication fills were for the brand-name choice, they made up 21.2% of total spending. Accounting for estimated brand-name rebates, generic substitution for these medications would save $641 million, including $135 million in costs shouldered by patients. Furthermore, the minority of clinicians with the lowest generic utilization was responsible for a large proportion of the potential cost savings. CONCLUSIONS: There are substantial potential cost savings from substituting brand-name medications with generic medications. These savings would be primarily driven by lower use of brand-name therapies by the minority of clinicians who prescribe them at increased rates.

Outcomes in patients with acute myocardial infarction and history of illicit drug use: a French nationwide analysis.

AIMS: Several reports suggest that illicit drug use may be a major cause of acute myocardial infarction (AMI) independently of smoking habits and associated with a poorer prognosis. The aim of our study was to evaluate the impact of illicit drug use on (i) the risk of AMI and (ii) its prognosis. METHODS AND RESULTS: This French longitudinal cohort study was based on the administrative hospital-discharge database from the entire population. First, we collected data for all patients admitted in hospital in 2013 with at least 5 years of follow-up to identify potential predictors of AMI. In a second phase, we collected data for all patients admitted with AMI from January 2010 to December 2018. We identified patients with a history of illicit drug use (cannabis, cocaine, or opioid). These patients were matched with patients without illicit drug use to assess their prognosis. In 2013, 3 381 472 patients were hospitalized with a mean follow-up of 4.7 ± 1.8 years. In multivariable analysis, among all drugs under evaluation, only cannabis use was significantly associated with a higher risk of AMI [HR 1.32 (95% CI 1.09-1.59), P = 0.004]. Between January 2010 and December 2018, we then identified 738 899 AMI patients. Among these patients, 3827 (0.5%) had a known history of illicit drug use. These patients were younger, most often male and had less comorbidities. After 1:1 propensity score matching, during a mean follow-up of 1.9 ± 2.3 years, there was no significant difference between patients without illicit drug use and patients with illicit drug use regarding all-cause death, cardiovascular death, stroke, or heart failure. CONCLUSION: In a large and systematic nationwide analysis, cannabis use was an independent risk factor for the incidence of AMI. However, the prognosis of illicit drug users presenting with AMI was similar to patients without illicit drug use.

Availability of Cost-effectiveness Studies for Drugs With High Medicare Part D Expenditures.

Importance: Prescription drug spending in the US requires policy intervention to control costs and improve the value obtained from pharmaceutical spending. One such intervention is to apply cost-effectiveness evidence to decisions regarding drug coverage and pricing, but this intervention depends on the existence of such evidence to guide decisions. Objective: To characterize the availability and quality of cost-effectiveness studies for prescription drugs with the greatest Medicare Part D spending. Design, Setting, and Participants: In this national cross-sectional analysis, publicly available 2016 Medicare drug spending records were merged with 2016 US Food & Drug Administration Orange Book data and the Tufts Medical Center Cost-Effectiveness Analysis (CEA) Registry. All studies published through 2015 that evaluated the cost-effectiveness of the 250 drugs for which Medicare Part D spending was the greatest in US-based adult patient populations were included. Data were analyzed from September 2018 to June 2020. Main Outcomes and Measures: The presence and quality of published cost-effectiveness analyses for the 250 drugs for which Medicare Part D spending was greatest in 2016 were assessed based on the inclusion of key cost-effectiveness analysis elements and global ratings by independent reviewers for the Tufts CEA Registry. Results: Medicare Part D spending on the 250 drugs in the sample totaled $122.8 billion in 2016 (84.1% of total spending). Of these 250 drugs, 91 (36.4%) had a generic equivalent and 159 (63.6%) retained some patent exclusivity. There were 280 unique cost-effectiveness analyses for these drugs, representing data on 135 (54.0%) of the 250 drugs included and 67.0% of Part D spending on the top 250 drugs. The 115 drugs (46.0%) without cost-effectiveness studies accounted for 33.0% of Part D spending on the top 250 drugs. Of the 280 available studies, 128 (45.7%) were industry sponsored. A large proportion of the studies (250 [89.3%]) did not meet the minimum quality requirements. Conclusions and Relevance: In this cross-sectional study, a substantial proportion of 2016 Medicare Part D spending was for drugs with absent or low-quality cost-effectiveness analyses. The lack of quality analyses may present a challenge in efforts to develop policies addressing drug spending in terms of value.

Characteristics and outcomes of patients hospitalized for COVID-19 in France: The Critical COVID-19 France (CCF) study.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has led to a public health crisis. Only limited data are available on the characteristics and outcomes of patients hospitalized for COVID-19 in France. AIMS: To investigate the characteristics, cardiovascular complications and outcomes of patients hospitalized for COVID-19 in France. METHODS: The Critical COVID-19 France (CCF) study is a French nationwide study including all consecutive adults with a diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) infection hospitalized in 24 centres between 26 February and 20 April 2020. Patients admitted directly to intensive care were excluded. Clinical, biological and imaging parameters were systematically collected at hospital admission. The primary outcome was in-hospital death. RESULTS: Of 2878 patients included (mean±SD age 66.6±17.0 years, 57.8% men), 360 (12.5%) died in the hospital setting, of which 7 (20.7%) were transferred to intensive care before death. The majority of patients had at least one (72.6%) or two (41.6%) cardiovascular risk factors, mostly hypertension (50.8%), obesity (30.3%), dyslipidaemia (28.0%) and diabetes (23.7%). In multivariable analysis, older age (hazard ratio [HR] 1.05, 95% confidence interval [CI] 1.03-1.06; P<0.001), male sex (HR 1.69, 95% CI 1.11-2.57; P=0.01), diabetes (HR 1.72, 95% CI 1.12-2.63; P=0.01), chronic kidney failure (HR 1.57, 95% CI 1.02-2.41; P=0.04), elevated troponin (HR 1.66, 95% CI 1.11-2.49; P=0.01), elevated B-type natriuretic peptide or N-terminal pro-B-type natriuretic peptide (HR 1.69, 95% CI 1.0004-2.86; P=0.049) and quick Sequential Organ Failure Assessment score ≥2 (HR 1.71, 95% CI 1.12-2.60; P=0.01) were independently associated with in-hospital death. CONCLUSIONS: In this large nationwide cohort of patients hospitalized for COVID-19 in France, cardiovascular comorbidities and risk factors were associated with a substantial morbi-mortality burden.

History of heart failure in patients with coronavirus disease 2019: Insights from a French registry.

BACKGROUND: Although cardiovascular comorbidities seem to be strongly associated with worse outcomes in patients with coronavirus disease 2019 (COVID-19), data regarding patients with preexisting heart failure are limited. AIMS: To investigate the incidence, characteristics and clinical outcomes of patients with COVID-19 with a history of heart failure with preserved or reduced ejection fraction. METHODS: We performed an observational multicentre study including all patients hospitalized for COVID-19 across 24 centres in France from 26 February to 20 April 2020. The primary endpoint was a composite of in-hospital death or need for orotracheal intubation. RESULTS: Overall, 2809 patients (mean age 66.4±16.9years) were included. Three hundred and seventeen patients (11.2%) had a history of heart failure; among them, 49.2% had heart failure with reduced ejection fraction and 50.8% had heart failure with preserved ejection fraction. COVID-19 severity at admission, defined by a quick sequential organ failure assessment score>1, was similar in patients with versus without a history of heart failure. Before and after adjustment for age, male sex, cardiovascular comorbidities and quick sequential organ failure assessment score, history of heart failure was associated with the primary endpoint (hazard ratio [HR]: 1.41, 95% confidence interval [CI]: 1.06-1.90; P=0.02). This result seemed to be mainly driven by a history of heart failure with preserved ejection fraction (HR: 1.61, 95% CI: 1.13-2.27; P=0.01) rather than heart failure with reduced ejection fraction (HR: 1.19, 95% CI: 0.79-1.81; P=0.41). CONCLUSIONS: History of heart failure in patients with COVID-19 was associated with a higher risk of in-hospital death or orotracheal intubation. These findings suggest that patients with a history of heart failure, particularly heart failure with preserved ejection fraction, should be considered at high risk of clinical deterioration.

Long-term evolution of stents implanted in branch pulmonary arteries.

BACKGROUND: Branch pulmonary artery stenosis complicates the management of congenital heart diseases. Surgical branch pulmonary artery angioplasty is associated with a high reintervention rate. As an alternative, percutaneous or intraoperative branch pulmonary artery stents have been implanted to improve efficiency, but long-term evaluations are limited. AIM: To describe the long-term evolution of branch pulmonary artery stents. METHODS: We conducted a retrospective cohort study at Tours University Hospital. All stents implanted by surgery or catheterization in branch pulmonary arteries with a minimum follow-up of 12 months and at least one catheterization control were included. The primary endpoint combined cardiovascular mortality, surgical or percutaneous reintervention for stent complication or new stent implantation. RESULTS: Between 2007 and 2017, 76 stents in 51 patients were included (62 stents implanted by surgery, 14 by catheterization). At implantation, the patients' mean age and weight were 4.7years (interquartile range 4.2years) and 17.3kg (interquartile range 11.0kg), respectively. Mean branch pulmonary artery minimum diameter was 4.1±2.1mm (mean Z-score-4.9±2.9), and mean initial stent diameter was 9.1±3.1mm. During a follow-up of 5.3years (range 0-11.2 years), freedom from primary endpoint was 86.8% (95% confidence interval 79.6-94.8%) at 1 year, 71.5% (95% confidence interval 61.9-82.7%) at 5years and 69.6% (95% confidence interval 59.6-81.2%) at 10 years. We did not identify any factors associated with major adverse cardiovascular events. Among stents without major adverse cardiovascular events, the mean branch pulmonary artery diameter Z-score at last evaluation had increased by +4.8±3.2 compared with the initial diameter (P<0.001). After stent implantation, a median of 2 re-expansions were performed for each stent (range 0-7). CONCLUSIONS: Stent implantation should offer a good long-term solution for branch pulmonary artery stenosis, although iterative re-expansions are required.

Perforation of the atretic pulmonary valve using chronic total occlusion (CTO) wire and coronary microcatheter.

BACKGROUND AND OBJECTIVE: Chronic total occlusion (CTO) guidewire have been recently reported as an alternative to radiofrequency for perforating atretic pulmonary valve. Since procedure failures or perforation of the right ventricle still occurred with CTO, we tried to enhance the stability, steering, and pushability of the wire using a microcatheter in order to improve the safety and efficacy of the procedure. METHODS: We performed pulmonary valve perforation with CTO guidewire and microcatheter in five consecutive newborns with pulmonary atresia with intact ventricular septum (PA-IVS) under fluoroscopic and echocardiographic control. RESULTS: The valve was easily perforated at the first attempt for all patients. After perforation, the microcatheter positioned in the main pulmonary artery allowed the exchange of the CTO guidewire for a more flexible wire, avoiding lesion and facilitating manipulation in the distal pulmonary branch arteries. The pulmonary valve was then dilated with balloons of increasing size as usually performed. We did not experience any procedural or early complications. Blalock-Taussig shunt was performed in 2 children because of a persistent cyanosis, 4 and 10 days after perforation. CONCLUSIONS: The combined use of a CTO guide and a microcatheter appears to be a safe and reliable technique for perforating the pulmonary valve of newborns with PA-IVS. Further procedures with this approach are needed to confirm this first experience.

More is better: students describe successful and unsuccessful experiences with teachers differently in brief and longitudinal relationships.

PURPOSE: Clerkship experiences that structure student-teacher continuity may promote learning differently than brief student-teacher relationships. The authors compared students' successful and unsuccessful teaching experiences in brief and longitudinal relationships. METHOD: A multicenter, qualitative interview study was conducted in 2009-2010 of students in two clerkship models that provide different durations of student-teacher relationships. Each student described a successful and unsuccessful teaching relationship early and late in the core clerkship year. Questions explored teachers' strategies and behaviors and students' efforts to improve unsuccessful relationships. Interview transcripts were coded to identify major themes. RESULTS: Fifty-four students completed interviews. Students in brief relationships struggled to be known; students in longitudinal relationships felt respected as learners and partners. Teaching strategies differed in the two relationship durations. Questioning about factual knowledge was common in brief relationships; collaborative knowledge sharing and application to patients occurred in longitudinal relationships. Hierarchy characterized brief relationships. Longitudinal students experienced evolving expectations in response to their growing skills and contributions. Only students in longitudinal relationships described successfully intervening to improve unsuccessful relationships; students in brief relationships felt powerless. CONCLUSIONS: Clerkship students in brief relationships learn to adapt to teachers' preferences and questioning to facilitate their participation and knowledge acquisition; longitudinal students experience collaborative interactions focused on their development as care providers. In longitudinal relationships, students gain confidence to influence their own learning and modify circumstances to meet their learning needs. These findings suggest that medical students' clinical experiences may be enhanced by deliberately structuring longitudinal attachments to supervisors.

The role of role: learning in longitudinal integrated and traditional block clerkships.

CONTEXT: Traditional block clerkship (BC) structures may not optimally support medical student participation in the workplace, whereas longitudinal integrated clerkship (LIC) structures seem more conducive to students' active engagement in patient care over time. Understanding the ways in which these two clerkship models influence students' roles and responsibilities can inform clinical learning programme design. METHODS: This was a multicentre qualitative study. We conducted semi-structured interviews with LIC and BC medical students at three institutions early and late in the core clinical year to explore their experiences with patients and the roles they served. Using the framework of 'workplace affordances', qualitative coding focused on students' roles and qualities of the learning environment that invited or inhibited student participation. We compared transcripts of early- and late-year interviews to assess students' changing roles and conducted discrepant case analysis to ensure that coding fit the data. RESULTS: Fifty-four students participated in interviews. They described serving three major roles in clinical care that respectively involved: providing support to patients; sharing information about patients across health care settings, and functioning in a doctor-like role. Both LIC and BC students served in the providing support and transmitting information roles both early and late in the year. By contrast, LIC students commonly served in the doctor-like role in managing their patients' care, particularly late in the year, whereas BC students rarely served in this role. Continuity in settings and in supervisors, and preceptors' endorsement of students' legitimate role afforded opportunities for students to participate actively in patient care. CONCLUSIONS: Although both LIC and BC students reported serving in important roles in supporting their patients and sharing information about their care, only LIC students consistently described opportunities to grow into a doctor role with patients. The high level of integration of LIC students into care systems and their deeper relationships with preceptors and patients enhanced their motivation and feelings of competence to provide patient-centred care.

Transcriptional profiling of Vero E6 cells over-expressing SARS-CoV S2 subunit: insights on viral regulation of apoptosis and proliferation.

We have previously demonstrated that over-expression of spike protein (S) of severe acute respiratory syndrome coronavirus (SARS-CoV) or its C-terminal subunit (S2) is sufficient to induce apoptosis in vitro. To further investigate the possible roles of S2 in SARS-CoV-induced apoptosis and pathogenesis of SARS, we characterized the host expression profiles induced upon S2 over-expression in Vero E6 cells by oligonucleotide microarray analysis. Possible activation of mitochondrial apoptotic pathway in S2 expressing cells was suggested, as evidenced by the up-regulation of cytochrome c and down-regulation of the Bcl-2 family anti-apoptotic members. Inhibition of Bcl-2-related anti-apoptotic pathway was further supported by the diminution of S2-induced apoptosis in Vero E6 cells over-expressing Bcl-xL. In addition, modulation of CCN E2 and CDKN 1A implied the possible control of cell cycle arrest at G1/S phase. This study is expected to extend our understanding on the pathogenesis of SARS at a molecular level.

Molecular mechanism of tumor necrosis factor-alpha modulation of intestinal epithelial tight junction barrier.

A TNF-alpha-induced increase in intestinal epithelial tight junction (TJ) permeability has been proposed to be an important proinflammatory mechanism contributing to intestinal inflammation in Crohn's disease and other inflammatory conditions. Previous studies from our laboratory suggested that the TNF-alpha-induced increase in intestinal TJ permeability was mediated by an increase in myosin light chain kinase (MLCK) protein expression. However, the molecular mechanisms that mediate the TNF-alpha increase in intestinal TJ permeability and MLCK protein expression remain unknown. The purpose of this study was to delineate the intracellular and molecular mechanisms that mediate the TNF-alpha-induced increase in intestinal TJ permeability; using an in vitro intestinal epithelial model system consisting of filter-grown Caco-2 intestinal epithelial monolayers. To examine the molecular mechanisms involved in the TNF-alpha regulation of intestinal TJ barrier, we identified and cloned for the first time a functionally active MLCK promoter region. TNF-alpha treatment of filter-grown Caco-2 monolayers transfected with plasmid vector containing the MLCK promoter region produced an increase in MLCK promoter activity and MLCK transcription. The TNF-alpha-induced increase in MLCK transcription corresponded to a sequential increase in MLCK protein expression, MLCK activity, and Caco-2 TJ permeability. The TNF-alpha-induced increase in MLCK promoter activity was mediated by NF-kappaB activation, and the inhibition of NF-kappaB activation prevented the TNF-alpha-induced increase in promoter activity and the subsequent increase in MLCK protein expression and Caco-2 TJ permeability. The TNF-alpha-induced activation of MLCK promoter was mediated by binding of the activated NF-kappaB p50/p65 dimer to the downstream kappaB binding site (-84 to -75) on the MLCK promoter region; deletion of the kappaB binding site prevented the TNF-alpha increase in promoter activity. Additionally, siRNA silencing of NF-kappaB p65 also prevented the TNF-alpha increase in MLCK promoter activity. In conclusion, our findings indicated that the TNF-alpha-induced increase in intestinal epithelial TJ permeability was mediated by NF-kappaB p50/p65 binding and activation of the MLCK promoter. NF-kappaB p50/p65 activation of the MLCK promoter then leads to a stepwise increase in MLCK transcription, expression and activity, and MLCK-mediated opening of the intestinal TJ barrier.

Novel biocompatible phosphorylcholine-based self-assembled nanoparticles for drug delivery.

Major challenges associated with nano-sized drug delivery systems include removal from systemic circulation by phagocytic cells and controlling appropriate drug release at target sites. 2-methacryloyloxyethyl phosphorylcholine (MPC) has been copolymerised in turn with two pH responsive comonomers (2-(diethylamino)ethyl methacrylate (DEA) and 2-(diisopropylamino)ethyl methacrylate (DPA), to develop novel biocompatible drug delivery vehicles. Micelles were prepared from a series of copolymers with varying block compositions and their colloidal stability and dimensions were assessed over a range of solution pH using photon correlation spectroscopy. The drug loading capacities of these micelles were evaluated using Orange OT dye as a model compound. The cytotoxicity of the micelles was assessed using an in vitro assay. The MPC-DEA diblock copolymers formed micelles at around pH 8 and longer DEA block lengths allowed higher drug loadings. However, these micelles were not stable at physiological pH. In contrast, MPC-DPA diblock copolymers formed micelles of circa 30 nm diameter at physiological pH. In vitro assays indicated that these MPC-DPA diblock copolymers had negligible cytotoxicities. Thus novel non-toxic biocompatible micelles of appropriate size and good colloidal stability with pH-modulated drug uptake and release can be readily produced using MPC-DPA diblock copolymers.