Cells respond to mechanical stress by rapid disassembly of caveolae.

The functions of caveolae, the characteristic plasma membrane invaginations, remain debated. Their abundance in cells experiencing mechanical stress led us to investigate their role in membrane-mediated mechanical response. Acute mechanical stress induced by osmotic swelling or by uniaxial stretching results in a rapid disappearance of caveolae, in a reduced caveolin/Cavin1 interaction, and in an increase of free caveolins at the plasma membrane. Tether-pulling force measurements in cells and in plasma membrane spheres demonstrate that caveola flattening and disassembly is the primary actin- and ATP-independent cell response that buffers membrane tension surges during mechanical stress. Conversely, stress release leads to complete caveola reassembly in an actin- and ATP-dependent process. The absence of a functional caveola reservoir in myotubes from muscular dystrophic patients enhanced membrane fragility under mechanical stress. Our findings support a new role for caveolae as a physiological membrane reservoir that quickly accommodates sudden and acute mechanical stresses.

A plasma metabolomic signature of Leber hereditary optic neuropathy showing taurine and nicotinamide deficiencies.

Leber's hereditary optic neuropathy (LHON) is the most common disorder due to mitochondrial DNA mutations and complex I deficiency. It is characterized by an acute vision loss, generally in young adults, with a higher penetrance in males. How complex I dysfunction induces the peculiar LHON clinical presentation remains an unanswered question. To gain an insight into this question, we carried out a non-targeted metabolomic investigation using the plasma of 18 LHON patients, during the chronic phase of the disease, comparing them to 18 healthy controls. A total of 500 metabolites were screened of which 156 were accurately detected. A supervised Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA) highlighted a robust model for disease prediction with a Q2 (cum) of 55.5%, with a reliable performance during the permutation test (cross-validation analysis of variance, P-value = 5.02284e-05) and a good prediction of a test set (P = 0.05). This model highlighted 10 metabolites with variable importance in the projection (VIP) > 0.8. Univariate analyses revealed nine discriminating metabolites, six of which were the same as those found in the Orthogonal Projections to Latent Structures Discriminant Analysis model. In total, the 13 discriminating metabolites identified underlining dietary metabolites (nicotinamide, taurine, choline, 1-methylhistidine and hippurate), mitochondrial energetic substrates (acetoacetate, glutamate and fumarate) and purine metabolism (inosine). The decreased concentration of taurine and nicotinamide (vitamin B3) suggest interesting therapeutic targets, given their neuroprotective roles that have already been demonstrated for retinal ganglion cells. Our results show a reliable predictive metabolomic signature in the plasma of LHON patients and highlighted taurine and nicotinamide deficiencies.

Ultrasensitive Troponin I and Incident Cardiovascular Disease.

BACKGROUND: To examine the association of ultrasensitive cTnI (cardiac troponin I) with incident cardiovascular disease events (CVDs) in the primary prevention setting. METHODS: cTnI was analyzed in the baseline plasma (2008-2012) of CVD-free volunteers from the Paris Prospective Study III using a novel ultrasensitive immunoassay (Simoa Troponin-I 2.0 Kit, Quanterix, Lexington) with a limit of detection of 0.013 pg/mL. Incident CVD hospitalizations (coronary heart disease, stroke, cardiac arrhythmias, deep venous thrombosis or pulmonary embolism, heart failure, or arterial aneurysm) were validated by critical review of the hospital records. Hazard ratios were estimated per log-transformed SD increase of cTnI in Cox models using age as the time scale. RESULTS: The study population includes 9503 participants (40% women) aged 59.6 (6.3) years. cTnI was detected in 99.6% of the participants (median value=0.63 pg/mL, interquartile range, 0.39-1.09). After a median follow-up of 8.34 years (interquartile range, 8.0-10.07), 516 participants suffered 612 events. In fully adjusted analysis, higher cTnI (per 1 SD increase of log cTnI) was significantly associated with CVD events combined (hazard ratio, 1.18 [1.08-1.30]). Among all single risk factors, cTnI had the highest discrimination capacity for incident CVD events (C index=0.6349). Adding log cTnI to the SCORE 2 (Systematic Coronary Risk Evaluation) risk improved moderately discriminatory capacity (C index 0.698 versus 0.685; bootstrapped C index difference: 0.0135 [95% CI, 0.0131-0.0138]), and reclassification of the participants (categorical net reclassification index, 0.0628 [95% CI, 0.023-0.102]). Findings were consistent using the US pooled cohort risk equation. CONCLUSIONS: Ultrasensitive cTnI is an independent marker of CVD events in the primary prevention setting.

Bioprosthetic Total Artificial Heart in Autoregulated Mode Is Biologically Hemocompatible: Insights for Multimers of von Willebrand Factor.

BACKGROUND: Carmat bioprosthetic total artificial heart (Aeson; A-TAH) is a pulsatile and autoregulated device. The aim of this study is to evaluate level of hemolysis potential acquired von Willebrand syndrome after A-TAH implantation. METHODS: We examined the presence of hemolysis and acquired von Willebrand syndrome in adult patients receiving A-TAH support (n=10) during their whole clinical follow-up in comparison with control subjects and adult patients receiving Heartmate II or Heartmate III support. We also performed a fluid structure interaction model coupled with computational fluid dynamics simulation to evaluate the A-TAH resulting shear stress and its distribution in the blood volume. RESULTS: The cumulative duration of A-TAH support was 2087 days. A-TAH implantation did not affect plasma free hemoglobin over time, and there was no association between plasma free hemoglobin and cardiac output or beat rate. For VWF (von Willebrand factor) evaluation, A-TAH implantation did not modify multimers profile of VWF in contrast to Heartmate II and Heartmate III. Furthermore, fluid structure interaction coupled with computational fluid dynamics showed a gradually increase of blood damage according to increase of cardiac output (P<0.01), however, the blood volume fraction that endured significant shear stresses was always inferior to 0.03% of the volume for both ventricles in all regimens tested. An inverse association between cardiac output, beat rate, and high-molecular weight multimers ratio was found. CONCLUSIONS: We demonstrated that A-TAH does not cause hemolysis or AWVS. However, relationship between HMWM and cardiac output depending flow confirms relevance of VWF as a biological sensor of blood flow, even in normal range.

Poor Masticatory Capacity and Blood Biomarkers of Elevated Cardiovascular Disease Risk in the Community: The Paris Prospective Study III.

[Figure: see text].

Sera Neutralizing Activities Against Severe Acute Respiratory Syndrome Coronavirus 2 and Multiple Variants 6 Months After Hospitalization for Coronavirus Disease 2019.

BACKGROUND: Humoral response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) occurs within the first weeks after coronavirus disease 2019 (COVID-19). Those antibodies exert a neutralizing activity against SARS-CoV-2, whose evolution over time after COVID-19 as well as efficiency against novel variants are poorly characterized. METHODS: In this prospective study, sera of 107 patients hospitalized with COVID-19 were collected at 3 and 6 months postinfection. We performed quantitative neutralization experiments on top of high-throughput serological assays evaluating anti-spike (S) and anti-nucleocapsid (NP) immunoglobulin G (IgG). RESULTS: Levels of seroneutralization and IgG rates against the ancestral strain decreased significantly over time. After 6 months, 2.8% of the patients had a negative serological status for both anti-S and anti-NP IgG. However, all sera had a persistent and effective neutralizing effect against SARS-CoV-2. IgG levels correlated with seroneutralization, and this correlation was stronger for anti-S than for anti-NP antibodies. The level of seroneutralization quantified at 6 months correlated with markers of initial severity, notably admission to intensive care units and the need for mechanical invasive ventilation. In addition, sera collected at 6 months were tested against multiple SARS-CoV-2 variants and showed efficient neutralizing effects against the D614G, B.1.1.7, and P.1 variants but significantly weaker activity against the B.1.351 variant. CONCLUSIONS: Decrease in IgG rates and serological assays becoming negative did not imply loss of neutralizing capacity. Our results indicate a sustained humoral response against the ancestral strain and the D614G, B.1.1.7, and P.1 variants for at least 6 months in patients previously hospitalized for COVID-19. A weaker protection was, however, observed for the B.1.351 variant.

STARD3 mediates endoplasmic reticulum-to-endosome cholesterol transport at membrane contact sites.

StAR-related lipid transfer domain-3 (STARD3) is a sterol-binding protein that creates endoplasmic reticulum (ER)-endosome contact sites. How this protein, at the crossroad between sterol uptake and synthesis pathways, impacts the intracellular distribution of this lipid was ill-defined. Here, by using in situ cholesterol labeling and quantification, we demonstrated that STARD3 induces cholesterol accumulation in endosomes at the expense of the plasma membrane. STARD3-mediated cholesterol routing depends both on its lipid transfer activity and its ability to create ER-endosome contacts. Corroborating this, in vitro reconstitution assays indicated that STARD3 and its ER-anchored partner, Vesicle-associated membrane protein-associated protein (VAP), assemble into a machine that allows a highly efficient transport of cholesterol within membrane contacts. Thus, STARD3 is a cholesterol transporter scaffolding ER-endosome contacts and modulating cellular cholesterol repartition by delivering cholesterol to endosomes.

Eicosapentaenoic acid membrane incorporation impairs ABCA1-dependent cholesterol efflux via a protein kinase A signaling pathway in primary human macrophages.

A diet rich in n-3/n-6 polyunsaturated fatty acids (PUFAs) is cardioprotective. Dietary PUFAs affect the cellular phospholipids composition, which may influence the function of membrane proteins. We investigated the impact of the membrane incorporation of several PUFAs on ABCA1-mediated cholesterol efflux, a key antiatherogenic pathway. Arachidonic acid (AA) (C20:4 n-6) and docosahexaenoic acid (DHA) (C22:6 n-3) decreased or increased cholesterol efflux from J774 mouse macrophages, respectively, whereas they had no effect on efflux from human monocyte-derived macrophages (HMDM). Importantly, eicosapentaenoic acid (EPA) (C20:5 n-3) induced a dose-dependent reduction of ABCA1 functionality in both cellular models (-28% for 70µM of EPA in HMDM), without any alterations in ABCA1 expression. These results show that PUFA membrane incorporation does not have the same consequences on cholesterol efflux from mouse and human macrophages. The EPA-treated HMDM exhibited strong phospholipid composition changes, with high levels of both EPA and its elongation product docosapentaenoic acid (DPA) (C22:5 n-3), which is associated with a decreased level of AA. In HMDM, EPA reduced the ATPase activity of the membrane transporter. Moreover, the activation of adenylate cyclase by forskolin and the inhibition of cAMP phosphodiesterase by isobutylmethylxanthine restored ABCA1 cholesterol efflux in EPA-treated human macrophages. In conclusion, EPA membrane incorporation reduces ABCA1 functionality in mouse macrophages as well as in primary human macrophages and this effect seems to be PKA-dependent in human macrophages.

Eicosapentaenoic acid membrane incorporation impairs cholesterol efflux from cholesterol-loaded human macrophages by reducing the cholesteryl ester mobilization from lipid droplets.

A diet containing a high n-3/n-6 polyunsaturated fatty acids (PUFA) ratio has cardioprotective properties. PUFAs incorporation into membranes influences the function of membrane proteins. We investigated the impact of the membrane incorporation of PUFAs, especially eicosapentaenoic acid (EPA) (C20:5 n-3), on the anti-atherogenic cholesterol efflux pathways. We used cholesteryl esters (CE)-loaded human monocyte-derived macrophages (HMDM) to mimic foam cells exposed to the FAs for a long period of time to ensure their incorporation into cellular membranes. Phospholipid fraction of EPA cells exhibited high levels of EPA and its elongation product docosapentaenoic acid (DPA) (C22:5 n-3), which was associated with a decreased level of arachidonic acid (AA) (C20:4 n-6). EPA 70µM reduced ABCA1-mediated cholesterol efflux to apolipoprotein (apo) AI by 30% without any alteration in ABCA1 expression. The other tested PUFAs, DPA, docosahexaenoic acid (DHA) (C22:6 n-3), and AA, were also able to reduce ABCA1 functionality while the monounsaturated oleic FA slightly decreased efflux and the saturated palmitic FA had no impact. Moreover, EPA also reduced cholesterol efflux to HDL mediated by the Cla-1 and ABCG1 pathways. EPA incorporation did not hinder efflux in free cholesterol-loaded HMDM and did not promote esterification of cholesterol. Conversely, EPA reduced the neutral hydrolysis of cytoplasmic CE by 24%. The reduced CE hydrolysis was likely attributed to the increase in cellular TG contents and/or the decrease in apo E secretion after EPA treatment. In conclusion, EPA membrane incorporation reduces cholesterol efflux in human foam cells by reducing the cholesteryl ester mobilization from lipid droplets.

Rab7 is functionally required for selective cargo sorting at the early endosome.

The small GTPases of the Rab family act as a molecular switch regulating various aspects of membrane trafficking through the selective recruitment of effector proteins. Whereas Rab7 has been classically involved in the regulation of transport within the endolysosomal network, persistent controversy remains as to whether Rab7 also plays a role in earlier steps of endosomal trafficking. In this study, we show that Rab7 depletion or inactivation results in enlargement of both early and late endosomes. Rab7 depletion led to the retention of a significant fraction of internalized low-density lipoproteins (LDL) mainly in enlarged early endosomes (EE). As a result, LDL processing and the transcriptional regulation of sterol-sensitive genes were impaired. We found that Rab7 activity was also required for the sorting of the mannose-6-phosphate receptor, the interferon alpha-receptor and the Shiga toxin B-subunit. In contrast, epidermal growth factor (EGF) sorting at the EE or the recycling of transferrin and LDL-R were not affected by Rab7 depletion. Our findings demonstrate that in addition to regulating late endosomes (LE) to lysosomes transport, Rab7 plays a functional role in the selective sorting of distinct cargos at the EE and that the Rab5 to Rab7 exchange occurs early in the endosomal maturation process.

Contrasting effects of arachidonic acid and docosahexaenoic acid membrane incorporation into cardiomyocytes on free cholesterol turnover.

The preservation of a constant pool of free cholesterol (FC) is critical to ensure several functions of cardiomyocytes. We investigated the impact of the membrane incorporation of arachidonic acid (C20:4 ω6, AA) or docosahexaenoic acid (C22:6 ω3, DHA) as ω6 or ω3 polyunsaturated fatty acids (PUFAs) on cholesterol homeostasis in primary cultures of neonatal rat cardiac myocytes. We measured significant alterations to the phospholipid FA profiles, which had markedly different ω6/ω3 ratios between the AA and DHA cells (13 vs. 1). The AA cells showed a 2.7-fold lower cholesterol biosynthesis than the DHA cells. Overall, the AA cells showed 2-fold lower FC masses and 2-fold higher cholesteryl ester masses than the DHA cells. The AA cells had a lower FC to phospholipid ratio and higher triglyceride levels than the DHA cells. Moreover, the AA cells showed a 40% decrease in ATP binding cassette transporter A1 (ABCA1)-mediated and a 19% decrease in ABCG1-mediated cholesterol efflux than the DHA cells. The differences in cholesterol efflux pathways induced by AA or DHA incorporation were not caused by variations in ABCs transporter expression and were reduced when ABC transporters were overexpressed by exposure to LXR/RXR agonists. These results show that AA incorporation into cardiomyocyte membranes decreased the FC turnover by markedly decreasing the endogenous cholesterol synthesis and by decreasing the ABCA1- and ABCG1-cholesterol efflux pathways, whereas DHA had the opposite effects. We propose that these observations may partially contribute to the beneficial effects on the heart of a diet containing a high ω3/ω6 PUFA ratio.

Humoral complementomics - exploration of noninvasive complement biomarkers as predictors of renal cancer progression.

Despite the progress of anti-cancer treatment, the prognosis of many patients with solid tumors is still dismal. Reliable noninvasive biomarkers are needed to predict patient survival and therapy response. Here, we propose a Humoral Complementomics approach: a work-up of assays to comprehensively evaluate complement proteins, activation fragments, and autoantibodies targeting complement proteins in plasma, which we correlated with the intratumoral complement activation, and/or local production, focusing on localized and metastatic clear cell renal cell carcinoma (ccRCC). In two prospective ccRCC cohorts, plasma C2, C5, Factor D and properdin were elevated compared to healthy controls, reflecting an inflammatory phenotype that correlated with plasma calprotectin levels but did not associate with CRP or with patient prognosis. Conversely, autoantibodies against the complement C3 and the reduced form of FH (a tumor neo-epitope reported in lung cancer) correlated with a favorable outcome. Our findings pointed to a specific group of patients with elevated plasma C4d and C1s-C1INH complexes, indicating the initiation of the classical pathway, along with elevated Ba and Bb, indicating alternative pathway activation. Boostrapped Lasso regularized Cox regression revealed that the most predictive complement biomarkers were elevated plasma C4d and Bb levels at the time of surgery, which correlated with poor prognosis. In conclusion, we propose Humoral Complementomics as an unbiased approach to study the global state of the complement system in any pathological plasma sample and disease context. Its implementation for ccRCC revealed that elevated C4d and Bb in plasma are promising prognostic biomarkers, correlating with shorter progression-free survival.

Deleterious impact of elaidic fatty acid on ABCA1-mediated cholesterol efflux from mouse and human macrophages.

Consumption of trans fatty acids (TFA) increase cardiovascular risk more than do saturated FA, but the mechanisms explaining their atherogenicity are still unclear. We investigated the impact of membrane incorporation of TFA on cholesterol efflux by exposing J774 mouse macrophages or human monocyte-derived macrophages (HMDM) to media enriched or not (standard medium) with industrially produced elaidic (trans-9 18:1) acid, naturally produced vaccenic (trans-11 18:1) acid (34 h, 70 µM) or palmitic acid. In J774 macrophages, elaidic and palmitic acid, but not vaccenic acid, reduced ABCA1-mediated efflux by ~23% without affecting aqueous diffusion, SR-BI or ABCG1-mediated pathways, and this effect was maintained in cholesterol-loaded cells. The impact of elaidic acid on the ABCA1 pathway was weaker in cholesterol-normal HMDM, but elaidic acid induced a strong reduction of ABCA1-mediated efflux in cholesterol-loaded cells (-36%). In J774 cells, the FA supplies had no impact on cellular free cholesterol or cholesteryl ester masses, the abundance of ABCA1 mRNA or the total and plasma membrane ABCA1 protein content. Conversely, TFA or palmitic acid incorporation induced strong modifications of the membrane FA composition with a decrease in the ratio of (cis-monounsaturated FA+polyunsaturated FA):(saturated FA+TFA), with elaidic and vaccenic acids representing each 20% and 13% of the total FA composition, respectively. Moreover, we demonstrated that cellular ATP was required for the effect of elaidic acid, suggesting that it contributes to atherogenesis by impairing ABCA1-mediated cholesterol efflux in macrophages, likely by decreasing the membrane fluidity, which could thereby reduce ATPase activity and the function of the transporter.

[Pernicious anemia with false normal vitamin B12 levels caused by intrinsic factor antibodies interference: a case report]. / Maladie de Biermer avec dosage de vitamine B12 faussement normal par interférence avec les anticorps anti-facteur intrinsèque : à propos d'un cas.

We present a case of a 48-year-old woman with a fortuitous discovery of macrocytic anemia and thrombocytopenia. Serum folate and vitamin B12 levels were normal. However, due to the presence of indirect signs of cobalamin deficiency, such as elevated homocysteine and methylmalonic acid, and signs of dyserythropoiesis on the bone marrow aspirate, pernicious anemia was suspected. Vitamin B12 dosage was repeated finding fluctuating but always normal results. Anti-intrinsic factor antibodies were present at a very high level, explaining the fluctuations and the interference found on the assay using competitive binding chemiluminescence (CBLA). Serum vitamin B12 dosage by electrochemiluminescence, a method described as not interfering with intrinsic factor antibodies, showed a collapsed vitamin B12 level. Measurement of vitamin B12 with CBLA after adsorption of immunoglobulins in the sample using protein G SepharoseTM, confirmed the interference of the cobalamin assay with autoantibodies. This case illustrates the difficulties regarding the analysis and standardization of the vitamin B12 assay for the diagnosis of pernicious anemia.

Involvement of cholesterol efflux pathway in the control of cardiomyocytes cholesterol homeostasis.

Although cholesterol-rich microdomains are highly involved in the functions of cardiomyocytes, the cholesterol homeostasis is largely unknown in these cells. We developed experimental procedures to assess cholesterol synthesis, cholesterol masses and cholesterol efflux from primary cultures of cardiac myocytes obtained from 2 to 4 days old Wistar rats. We first observed that cardiomyocytes poorly internalized exogenously supplied native or modified LDL and that free cholesterol (FC) efflux to free apolipoprotein AI (apo AI) and to HDL was mediated by ATP binding cassette transporter A1 (ABCA1) and likely by ATP binding cassette transporter G1 (ABCG1), respectively, which are both upregulated by liver X receptor/retinoid X receptor (LXR/RXR) activation. We then investigated the consequences of cholesterol synthesis inhibition on cholesterol homeostasis using an HMGCoA reductase inhibitor (pravastatin, 90% effective concentration (EC90): 0.11 mM, 18 h). We observed no impact of cholesterol synthesis inhibition on the FC or cholesteryl ester (CE) masses. Consistently with no FC mass changes, pravastatin treatment had no notable impact on LDL receptors mRNA expression or on the capacity of cardiomyocytes to uptake radiolabeled LDL. Conversely, pravastatin treatment induced a significant decrease of cholesterol efflux to both apo AI and HDL whereas the passive aqueous diffusion remained unchanged. The cholesterol efflux pathway reductions induced by cholesterol synthesis inhibition were not caused by a reduction of ABC transporter expression (mRNA or protein). These results show that cardiac myocytes down-regulate active cholesterol efflux processes when endogenous cholesterol synthesis is inhibited, allowing them to preserve cholesterol homeostasis.

Clinical diagnosis, outcomes and treatment of thiamine deficiency in a tertiary hospital.

BACKGROUND: Acute thiamine deficiency can occur in patients with or without history of alcohol abuse and can lead to life-threatening complications. Clinical diagnosis is challenging, often resulting in delayed recognition and treatment. Patients may present with heterogenous symptoms, more diverse than the historical neurological description. Cerebral MRI can contribute to the diagnosis in patients with neurological signs but it is not always feasible in emergency settings. Prompt parenteral supplementation is required to obtain the improvement of symptoms and avoid chronic complications. AIMS: To describe the clinical presentation of reported cases of thiamine deficiency, assess prescription and results of cerebral imaging, review treatments that had been prescribed in accordance or not with available guidelines, and study the short-term outcome of these patients. METHODS: This is a monocentric retrospective analysis of all reported cases of thiamine deficiency in a French tertiary hospital between January 1st 2008 and December 31st 2018. RESULTS: Fifty-six cases were identified during the study period. Forty-five (80%) patients had a history of alcohol abuse. Most patients were diagnosed based on neurological symptoms but non-specific and digestive symptoms were frequent. Thirty-four percent of patients fulfilled clinical criteria for malnutrition. A brain MRI was performed in 54% of patients and was abnormal in 63% of these cases. Eighty-five percent of patients were treated by parenteral thiamine administration and the supplementation was continued orally in 55% of them. The majority of patients initially received 1000 mg daily of IV thiamine but the dose and duration of thiamine supplementation were variable. At the time of discharge, partial or complete improvement of symptoms was noted in 59% of patients. CONCLUSION: This study highlights the clinical and radiological heterogeneity of thiamine deficiency. These observations should encourage starting thiamine supplementation early in patients with risk factors or suggestive symptoms even in non-alcoholic patients, and underline the importance of early nutritional support.

Imbalance between alpha-1-antitrypsin and interleukin 6 is associated with in-hospital mortality and thrombosis during COVID-19.

Thrombosis is a hallmark of severe COVID-19. Alpha-1-antitrypsin (AAT), an inflammation-inducible serpin with anti-inflammatory, tissue protective and anticoagulant properties may be involved in severe COVID-19 pathophysiology including thrombosis onset. In this study, we examined AAT ability to predict occurrence of thrombosis and in-hospital mortality during COVID-19. To do so, we performed a monocentric cross-sectional study of 137 hospitalized patients with COVID-19 of whom 56 (41%) were critically ill and 33 (22.4%) suffered from thrombosis during hospitalization. We measured AAT and IL-6 plasma levels in all patients and phenotyped AAT in a subset of patients with or without thrombosis paired for age, sex and COVID-19 severity. We observed that AAT levels at admission were higher in both non-survivors and thrombosis patients than in survivors and non-thrombosis patients. AAT: IL-6 ratio was lower in non-survivors and thrombosis patients. In a logistic regression multivariable analysis model adjusted on age, BMI and D-dimer levels, a higher AAT: IL-6 was a protective factor of both in-hospital mortality (Odds ratio, OR: 0.07 95%CI [0.02-0.25], p < 0.001) and thrombosis (OR 0.36 95%CI [0.14-0.82], p = 0.02). AAT phenotyping did not show a higher proportion of AAT abnormal variants in thrombosis patients.Our findings suggest an insufficient production of AAT regarding inflammation intensity during severe COVID-19. AAT appeared as a powerful predictive marker of severity, mortality and thrombosis mirroring the imbalance between harmful inflammation and protective counter-balancing mechanism in COVID-19. Restoring the balance between AAT and inflammation could offer therapeutic opportunities in severe COVID-19.

Clarifying the relationship between pulmonary langerhans cell histiocytosis and Alpha 1 antitrypsin deficiency.

Pulmonary Langerhans cell histiocytosis (PLCH) is a rare, smoking related, progressive diffuse cystic lung disease that occurs primarily in smokers. The aim of this study was to determine if there was an increase in alpha-1 antitrypsin deficient alleles or phenotypes in a large series of PLCH patients and whether serum alpha-1 antitrypsin levels correlated with markers of disease severity. Fifty PLCH patients, 24 with a diffuse cystic lung pattern and 26 with a typical nodulo-cystic pattern on imaging were included. The mean alpha-1 antitrypsin levels were in normal range for both the population with diffuse cystic lung pattern population (1.39 g/L ± 0.37) and the nodulo-cystic pattern group (1.41 g/L ± 0.21). Deficiency alleles PiZ and PiS were 1% and 2% respectively in the entire study population of 50 patients, demonstrating no increased incidence of alpha-1 antitrypsin deficiency in PLCH. Alpha-1 antitrypsin levels showed no correlation with lung function parameters or extent of cystic lesions on lung computed tomography.

No SARS-CoV-2 reinfection among staff health-care workers: Prospective hospital-wide screening during the first and second waves in Paris.

OBJECTIVES: Risk of reinfection with SARS-CoV-2 among health-care workers (HCWs) is unknown. We assessed the incidence rate of SARS-CoV-2 reinfection in the real-life setting of a longitudinal observational cohort of HCWs from the Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, France, during the first and second waves of COVID-19 epidemic. METHODS: From March to December 2020, HCWs were subjected to molecular and serology testing of SARS-CoV-2. Reinfection was defined as a positive test result during the first wave, either by serology or PCR, followed by a positive PCR during the second wave. Evolution of COVID-19 status of HWCs was assessed by a Sankey diagram. RESULTS: A total of 7765 tests (4579 PCR and 3186 serology) were carried out and 4168 HCWs had at least one test result during the follow-up period with a positivity rate of 15.9%. No case of reinfection during the second wave could be observed among 102 positive HCWs of the first wave, nor among 175 HCWs found positive by PCR during the second wave who were negative during the first wave. CONCLUSIONS: SARS-CoV-2 reinfection was not observed among HCWs, suggesting a protective immunity against reinfection that lasts at least 8 months post infection.

Eicosapentaenoic acid membrane incorporation stimulates ABCA1-mediated cholesterol efflux from human THP-1 macrophages.

A high intake in polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic acid (EPA) (C20:5 n-3), is cardioprotective. Dietary PUFAs incorporate into membrane phospholipids, which may modify the function of membrane proteins. We investigated the consequences of the membrane incorporation of several PUFAs on the key antiatherogenic ABCA1-mediated cholesterol efflux pathway. Human THP-1 macrophages were incubated with EPA, arachidonic acid (AA) (C20:4 n-6) or docosahexaenoic acid (DHA) (C22:6 n-3) for a long time to mimic a chronic exposure. EPA 70 µM, but not AA 50 µM or DHA 15 µM, increased ABCA1-mediated cholesterol efflux to apolipoprotein (apo) AI by 28% without altering aqueous diffusion. No variation in ABCA1 expression or localization was observed after EPA treatment. EPA incorporation did not affect the phenotype of THP-1 macrophages. The membrane phospholipids composition of EPA cells displayed higher levels of both EPA and its elongation product docosapentaenoic acid, which was associated with drastic lower levels of AA. Treatment by EPA increased the ATPase activity of the transporter, likely through a PKA-dependent mechanism. Eicosanoids were not involved in the stimulated ABCA1-mediated cholesterol efflux from EPA-enriched macrophages. In addition, EPA supplementation increased the apo AI binding capacity from macrophages by 38%. Moreover, the increased apo AI binding in EPA-enriched macrophages can be competed. In conclusion, EPA membrane incorporation increased ABCA1 functionality in cholesterol-normal human THP-1 macrophages, likely through a combination of different mechanisms. This beneficial in vitro effect may partly contribute to the cardioprotective effect of a diet enriched with EPA highlighted by several recent clinical trials.