Folate regulation of planar cell polarity pathway and F-actin through folate receptor alpha.

Folate deficiency contribute to neural tube defects (NTDs) which could be rescued by folate supplementation. However, the underlying mechanisms are still not fully understood. Besides, there is considerable controversy concerning the forms of folate used for supplementation. To address this controversy, we prepared culture medium with different forms of folate, folic acid (FA), and 5-methyltetrahydrofolate (5mTHF), at concentrations of 5 µM, 500 nM, 50 nM, and folate free, respectively. Mouse embryonic fibroblasts (MEFs) were treated with different folates continuously for three passages, and cell proliferation and F-actin were monitored. We determined that compared to 5mTHF, FA showed stronger effects on promoting cell proliferation and F-actin formation. We also found that FOLR1 protein level was positively regulated by folate concentration and the non-canonical Wnt/planar cell polarity (PCP) pathway signaling was significantly enriched among different folate conditions in RNA-sequencing analyses. We demonstrated for the first time that FOLR1 could promote the transcription of Vangl2, one of PCP core genes. The transcription of Vangl2 was down-regulated under folate-deficient condition, which resulted in a decrease in PCP activity and F-actin formation. In summary, we identified a distinct advantage of FA in cell proliferation and F-actin formation over 5mTHF, as well as demonstrating that FOLR1 could promote transcription of Vangl2 and provide a new mechanism by which folate deficiency can contribute to the etiology of NTDs.

De novo heterozygous missense variants in CELSR1 as cause of fetal pleural effusions and progressive fetal hydrops.

Fetal hydrops as detected by prenatal ultrasound usually carries a poor prognosis depending on the underlying aetiology. We describe the prenatal and postnatal clinical course of two unrelated female probands in whom de novo heterozygous missense variants in the planar cell polarity gene CELSR1 were detected using exome sequencing. Using several in vitro assays, we show that the CELSR1 p.(Cys1318Tyr) variant disrupted the subcellular localisation, affected cell-cell junction, impaired planar cell polarity signalling and lowered proliferation rate. These observations suggest that deleterious rare CELSR1 variants could be a possible cause of fetal hydrops.

Could poor glycaemic control be a predictor of walking speed decline in older adults? Evidence from the English Longitudinal Study of Ageing.

AIM: Although diabetes is a risk factor for walking speed decline in older adults, it remains unclear how glycaemic control [assessed by glycated haemoglobin (HbA1c)] might affect the long-term trajectories of walking speed. We investigated whether the glycaemic control status accelerates the walking speed decline and whether this decline differs depending on previous mobility conditions. MATERIALS AND METHODS: In total, 3202 individuals aged ≥60 years from the English Longitudinal Study of Ageing (ELSA) were classified at baseline and after 4 and 8 years of follow-up according to glycaemic control status as 'without diabetes' (no self-reported diabetes and HbA1c <6.5%), 'good glycaemic control' (self-reported diabetes and HbA1c ≥6.5% and <7.0%) and 'poor glycaemic control' (PGC) (self-reported diabetes and HbA1c ≥7.0%). The generalized linear mixed models verified the walking speed trajectories in m/s. A second analysis was performed, including only participants without slowness at baseline (>0.8 m/s). RESULTS: Compared with the status 'without diabetes', the annual walking speed decline was -0.015 m/s for PGC and -0.011 m/s for good glycaemic control, totalling -0.160 and -0.130 m/s, respectively, over 8 years. Among those without slowness at baseline, only PGC had a significant walking speed decline, corresponding to -0.014 m/s per year and -0.222 m/s over 8 years. CONCLUSIONS: Poor glycaemic control is a discriminator of walking speed decline in older adults, regardless of previous mobility conditions. It may serve as an early screening tool for those at risk of decreased functional performance later in life.

Does the coexistence of pain and depressive symptoms accelerate cognitive decline?

OBJECTIVES: Investigate whether the coexistence of pain and depressive symptoms is a risk factor for cognitive decline in individuals aged 50 or older. METHOD: Longitudinal trajectory study involving 4,718 participants from the English Longitudinal Study of Ageing (ELSA). Joint pain was self-reported, and intensity was classified as mild, moderate/intense. Depressive symptoms were investigated using the Centre for Epidemiologic Studies Depression Scale (CES-D-8 ≥ 4). The sample was divided into six groups: no pain and no depression (NP/NDe), mild pain and no depression (MP/NDe), moderate/intense pain and no depression (M-IP/NDe), no pain and depression (NP/De), mild pain and depression (MP/De), and moderate/intense pain and depression (M-IP/De). The outcome of interest was performance in memory, executive function, and global cognition. Generalised linear mixed models were used to analyse performance in the cognitive domains and global cognition score as a function of pain and depressive symptoms during 12 years of follow-up. RESULTS: Over time, individuals with M-IP/De had a greater memory decline (-0.038 SD/year, 95%CI: -0.068 to -0.007) and the global cognition score (-0.033 SD/year, 95%CI: -0.063 to -0.002) than those with NP/NDe. CONCLUSION: The coexistence of moderate/intense pain and depressive symptoms is a risk factor for the decline of global cognition and memory.

Is dynapenic abdominal obesity a risk factor for cardiovascular mortality? A competing risk analysis.

BACKGROUND: Dynapenic abdominal obesity has been shown as a risk factor for all-cause mortality in older adults. However, there is no evidence on the association between this condition and cardiovascular mortality. OBJECTIVE: We aimed to investigate whether dynapenic abdominal obesity is associated with cardiovascular mortality in individuals aged 50 and older. METHODS: A longitudinal study with an 8-year follow-up was conducted involving 7,030 participants of the English Longitudinal Study of Ageing study. Abdominal obesity and dynapenia were respectively defined based on waist circumference (> 102 cm for men and > 88 cm for women) and grip strength (< 26 kg for men and < 16 kg for women). The sample was divided into four groups: non-dynapenic/non-abdominal obesity (ND/NAO), non-dynapenic/abdominal obesity (ND/AO), dynapenic/non-abdominal obesity (D/NAO) and dynapenic/abdominal obesity (D/AO). The outcome was cardiovascular mortality. The Fine-Grey regression model was used to estimate the risk of cardiovascular mortality as a function of abdominal obesity and dynapenia status in the presence of competing events controlled by socio-demographic, behavioural and clinical variables. RESULTS: The risk of cardiovascular mortality was significantly higher in individuals with D/AO compared with ND/NAO (SHR 1.85; 95% CI: 1.15-2.97). D/NAO was also associated with cardiovascular mortality (SHR: 1.62; 95% CI: 1.08-2.44). CONCLUSION: Dynapenic abdominal obesity is associated with cardiovascular mortality, with a larger effect size compared to dynapenia alone in individuals older than 50 years. Thus, prevention strategies and clinical interventions that enable mitigating the harmful effects of these conditions should be adopted to diminish such risk.

Increase in lamin B1 promotes telomere instability by disrupting the shelterin complex in human cells.

Telomere maintenance is essential to preserve genomic stability and involves telomere-specific proteins, DNA replication and repair proteins. Lamins are key components of the nuclear envelope and play numerous roles, including maintenance of the nuclear integrity, regulation of transcription, and DNA replication. Elevated levels of lamin B1, one of the major lamins, have been observed in some human pathologies and several cancers. Yet, the effect of lamin B1 dysregulation on telomere maintenance remains unknown. Here, we unveil that lamin B1 overexpression drives telomere instability through the disruption of the shelterin complex. Indeed, lamin B1 dysregulation leads to an increase in telomere dysfunction-induced foci, telomeric fusions and telomere losses in human cells. Telomere aberrations were preceded by mislocalizations of TRF2 and its binding partner RAP1. Interestingly, we identified new interactions between lamin B1 and these shelterin proteins, which are strongly enhanced at the nuclear periphery upon lamin B1 overexpression. Importantly, chromosomal fusions induced by lamin B1 in excess were rescued by TRF2 overexpression. These data indicated that lamin B1 overexpression triggers telomere instability through a mislocalization of TRF2. Altogether our results point to lamin B1 as a new interacting partner of TRF2, that is involved in telomere stability.

Grafting of Crown Ether and Cryptand Macrocycles on Large Pore Stellate Mesoporous Silica for Sodium Cation Extraction.

Regulation of the sodium cations level in the case of renal failure diseases is a very challenging task for clinicians, and new pollutant extractors based on nanomaterials are emerging as potential treatments. In this work, we report different strategies for the chemical functionalization of biocompatible large pore mesoporous silica, denoted stellate mesoporous silica (STMS), with chelating ligands able to selectively capture sodium. We address efficient methods to covalently graft highly chelating macrocycles onto STMS NPs such as crown ethers (CE) and cryptands (C221) through complementary carbodiimidation reactions. Regarding sodium capture in water, C221 cryptand-grafted STMS showed better capture efficiency than CE-STMS due to higher sodium atom chelation in the cryptand cage (Na+ coverage of 15.5% vs. 3.7%). The sodium selectivity was hence tested with C221 cryptand-grafted STMS in a multi-element aqueous solution (metallic cations with the same concentration) and in a solution mimicking peritoneal dialysis solution. Results obtained indicate that C221 cryptand-grafted STMS are relevant nanomaterials to extract sodium cations in such media and allow us to regulate their levels.

CIC missense variants contribute to susceptibility for spina bifida.

Neural tube defects (NTDs) are congenital malformations resulting from abnormal embryonic development of the brain, spine, or spinal column. The genetic etiology of human NTDs remains poorly understood despite intensive investigation. CIC, homolog of the Capicua transcription repressor, has been reported to interact with ataxin-1 (ATXN1) and participate in the pathogenesis of spinocerebellar ataxia type 1. Our previous study demonstrated that CIC loss of function (LoF) variants contributed to the cerebral folate deficiency syndrome by downregulating folate receptor 1 (FOLR1) expression. Given the importance of folate transport in neural tube formation, we hypothesized that CIC variants could contribute to increased risk for NTDs by depressing embryonic folate concentrations. In this study, we examined CIC variants from whole-genome sequencing (WGS) data of 140 isolated spina bifida cases and identified eight missense variants of CIC gene. We tested the pathogenicity of the observed variants through multiple in vitro experiments. We determined that CIC variants decreased the FOLR1 protein level and planar cell polarity (PCP) pathway signaling in a human cell line (HeLa). In a murine cell line (NIH3T3), CIC loss of function variants downregulated PCP signaling. Taken together, this study provides evidence supporting CIC as a risk gene for human NTD.

Are Serum 25-Hydroxyvitamin D Deficiency and Insufficiency Risk Factors for the Incidence of Dynapenia?

Epidemiological evidence showing the association between low 25(OH)D and age-related reduction in neuromuscular strength (dynapenia) is a paucity and controversial and, to date, the effect of osteoporosis and vitamin D supplementation on these associations has not been measured. Thus, we analyze whether serum 25(OH)D deficiency and insufficiency are risk factors for the incidence of dynapenia in individuals aged 50 or older and whether osteoporosis or vitamin D supplementation modify these associations. For that, 3205 participants of the ELSA study who were non-dynapenic at baseline were followed for 4 years. Vitamin D was measured at baseline by the serum concentration of 25(OH)D and classified as sufficient (> 50 nmol/L), insufficient (≥ 30 and ≤ 50 nmol/L) or deficient (< 30 nmol/L). The incidence of dynapenia was determined by a grip strength < 26 kg for men and < 16 kg for women at the end of the 4-year follow-up. Poisson regression models were adjusted by sociodemographic, behavioral, clinical and biochemical characteristics. Serum 25(OH)D deficient was a risk factor for the incidence of dynapenia (IRR = 1.70; 95% CI 1.04-2.79). When only individuals without osteoporosis and those who did not use vitamin D supplementation were analyzed, both serum 25(OH)D deficiency (IRR = 1.78; 95% CI 1.01-3.13) and insufficiency (IRR = 1.77; 95% CI 1.06-2.94) were risk factors for the incidence of dynapenia. In conclusion, a serum level of 25(OH)D < 30 nmol/L is a risk factor for the incidence of dynapenia. Among individuals without osteoporosis and those who do not take vitamin D supplementation, the threshold of risk is higher (≤ 50 nmol/L).

European Working Group on Sarcopenia in Older People 2010 (EWGSOP1) and 2019 (EWGSOP2) criteria or slowness: which is the best predictor of mortality risk in older adults?

OBJECTIVES: to analyse the accuracy of grip strength and gait speed in identifying mortality; to compare the association between mortality and sarcopenia defined by the EWGSOP1 and EWGSOP2 using the best cut-off found in the present study and those recommended in the literature and to test whether slowness is better than these two definitions to identify the risk of death in older adults. METHODS: a longitudinal study was conducted involving 6,182 individuals aged 60 or older who participated in the English Longitudinal Study of Ageing. Sarcopenia was defined based on the EWGSOP1 and EWGSOP2 using different cut-off for low muscle strength (LMS). Mortality was analysed in a 14-year follow-up. RESULTS: compared with the LMS definitions in the literature (<32, <30, <27 and < 26 kg for men; <21, <20 and < 16 kg for women), the cut-off of <36 kg for men (sensitivity = 58.59%, specificity = 72.96%, area under the curve [AUC] = 0.66) and < 23 kg for women (sensitivity = 68.90%, specificity = 59.03%, AUC = 0.64) as well as a low gait speed (LGS) ≤0.8 m/s (sensitivity = 53.72%, specificity = 74.02%, AUC = 0.64) demonstrated the best accuracy for mortality. Using the cut-off found in the present study, probable sarcopenia [HR = 1.30 (95%CI: 1.16-1.46)], sarcopenia [HR = 1.48 (95%CI: 1.24-1.78)] and severe sarcopenia [HR = 1.78 (95%CI: 1.49-2.12)] according to EWGSOP2 were better predictors of mortality risk than EWGSOP1. LGS ≤0.8 m/s was a better mortality risk predictor only when LMS was defined by low cut-off. CONCLUSIONS: using LMS <36 kg for men and < 23 kg for women and LGS ≤ 0.8 m/s, EWGSOP2 was the best predictor for mortality risk in older adults.

Soft drink and non-caloric soft drink intake and their association with blood pressure: the Health Workers Cohort Study.

BACKGROUND: A few prospective studies have investigated the potential association of soft drink and non-caloric soft drink intake with high blood pressure using methods that adequately consider changes in intake over time and hypertensive status at baseline. OBJECTIVE: To prospectively examine the association of soft drink and non-caloric soft drink intake with systolic and diastolic blood pressure in a sample of Mexican adults, overall and by hypertension status. METHODS: We used data from the Health Workers Cohort Study spanning from 2004 to 2018 (n = 1,324 adults). Soft drink and non-caloric soft drink intake were assessed with a semiquantitative food frequency questionnaire. We fit multivariable-adjusted fixed-effects models to test the association of soft drink and non-caloric soft drink intake with systolic and diastolic blood pressure. The models were adjusted for potential confounders and considering the potential modifying effect of hypertension status at baseline. RESULTS: A one-serving increase in soft drink intake was associated with a 2.08 mm Hg (95% CI: 0.21, 3.94) increase in systolic blood pressure and 2.09 mm Hg (95% CI: 0.81, 3.36) increase in diastolic blood pressure over ten years. A stronger association between soft drink intake and diastolic pressure was observed among participants with versus without hypertension at baseline. We found no association between non-caloric soft drink intake and blood pressure. CONCLUSIONS: Our findings support the hypothesis that soft drink intake increases blood pressure. While further studies should be conducted to confirm our findings, food policies and recommendations to limit soft drink intake are likely to help reduce blood pressure at the population level. We probably did not find an association between non-caloric soft drink intake and blood pressure because of the low consumption of this type of beverage in the cohort. More studies will be needed to understand the potential effect of non-caloric beverages on blood pressure.

Dynapenia, abdominal obesity or both: which accelerates the gait speed decline most?

OBJECTIVE: to investigate whether the combination of dynapenia and abdominal obesity is worse than these two conditions separately regarding gait speed decline over time. METHODS: a longitudinal study was conducted involving 2,294 individuals aged 60 years or older free of mobility limitation at baseline (gait speed >0.8 m/s) who participated in the English Longitudinal Study of Ageing. Dynapenia was determined as a grip strength <26 kg for men and <16 kg for women. Abdominal obesity was determined as a waist circumference >102 cm for men and >88 cm for women. The participants were divided into four groups: non-dynapenic/non-abdominal obese (ND/NAO); only abdominal obese (AO); only dynapenic (D) and dynapenic/abdominal obese (D/AO). Generalised linear mixed models were used to analyse gait speed decline (m/s) as a function of dynapenia and abdominal obesity status over an 8-year follow-up period. RESULTS: over time, only the D/AO individuals had a greater gait speed decline (-0.013 m/s per year, 95% CI: -0.024 to -0.002; P < 0.05) compared to ND/NAO individuals. Neither dynapenia nor abdominal obesity only was associated with gait speed decline. CONCLUSION: dynapenic abdominal obesity is associated with accelerated gait speed decline and is, therefore, an important modifiable condition that should be addressed in clinical practice through aerobic and strength training for the prevention of physical disability in older adults.

Orienting the Pore Morphology of Core-Shell Magnetic Mesoporous Silica with the Sol-Gel Temperature. Influence on MRI and Magnetic Hyperthermia Properties.

The controlled design of robust, well reproducible, and functional nanomaterials made according to simple processes is of key importance to envision future applications. In the field of porous materials, tuning nanoparticle features such as specific area, pore size and morphology by adjusting simple parameters such as pH, temperature or solvent is highly needed. In this work, we address the tunable control of the pore morphology of mesoporous silica (MS) nanoparticles (NPs) with the sol-gel reaction temperature (Tsg). We show that the pore morphology of MS NPs alone or of MS shell covering iron oxide nanoparticles (IO NPs) can be easily tailored with Tsg orienting either towards stellar (ST) morphology (large radial pore of around 10 nm) below 80 °C or towards a worm-like (WL) morphology (small randomly oriented pores channel network, of 3-4 nm pore size) above 80 °C. The relaxometric and magnetothermal features of IO@STMS or IO@WLMS core shell NPs having respectively stellar or worm-like morphologies are compared and discussed to understand the role of the pore structure for MRI and magnetic hyperthermia applications.

Association of Serum 25-Hydroxyvitamin D Deficiency with Risk of Incidence of Disability in Basic Activities of Daily Living in Adults >50 Years of Age.

BACKGROUND: Vitamin D deficiency compromises muscle function and is related to the etiology of several clinical conditions that can contribute to the development of disability. However, there are few epidemiological studies investigating the association between vitamin D deficiency and the incidence of disability. OBJECTIVES: We aimed to assess whether vitamin D deficiency is associated with the incidence of disability in basic activities of daily living (BADL) and to verify whether there are sex differences in this association. METHODS: A 4-y follow-up study was conducted involving individuals aged 50 y or older who participated in ELSA (English Longitudinal Study of Ageing). The sample consisted of 4814 participants free of disability at baseline according to the modified Katz Index. Vitamin D was assessed by serum 25-hydroxyvitamin D [25(OH)D] concentrations and the participants were classified as sufficient (>50 nmol/L), insufficient (>30 to ≤50 nmol/L), or deficient (≤30 nmol/L). Sociodemographic, behavioral, and clinical characteristics were also investigated. BADL were re-evaluated after 2 and 4 y of follow-up. The report of any difficulty to perform ≥1 BADL was considered as an incident case of disability. Poisson models stratified by sex and controlled for sociodemographic, behavioral, and clinical characteristics were carried out. RESULTS: After 4-y follow-up, deficient serum 25(OH)D was a risk factor for the incidence of BADL disability in both women (IRR: 1.53; 95% CI: 1.16, 2.03) and men (IRR: 1.44; 95% CI: 1.02, 2.02). However, insufficient serum 25(OH)D was not a risk factor for the incidence of BADL disability in either men or women. CONCLUSIONS: Independently of sex, deficient serum 25(OH)D concentrations were associated with increased risk of incidence of BADL disability in adults >50 y old and should be an additional target of clinical strategies to prevent disability in these populations.

Update of the treatment of nosocomial pneumonia in the ICU.

In accordance with the recommendations of, amongst others, the Surviving Sepsis Campaign and the recently published European treatment guidelines for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), in the event of a patient with such infections, empirical antibiotic treatment must be appropriate and administered as early as possible. The aim of this manuscript is to update treatment protocols by reviewing recently published studies on the treatment of nosocomial pneumonia in the critically ill patients that require invasive respiratory support and patients with HAP from hospital wards that require invasive mechanical ventilation. An interdisciplinary group of experts, comprising specialists in anaesthesia and resuscitation and in intensive care medicine, updated the epidemiology and antimicrobial resistance and established clinical management priorities based on patients' risk factors. Implementation of rapid diagnostic microbiological techniques available and the new antibiotics recently added to the therapeutic arsenal has been reviewed and updated. After analysis of the categories outlined, some recommendations were suggested, and an algorithm to update empirical and targeted treatment in critically ill patients has also been designed. These aspects are key to improve VAP outcomes because of the severity of patients and possible acquisition of multidrug-resistant organisms (MDROs).

Lower Respiratory Tract Infection and Short-Term Outcome in Patients With Acute Respiratory Distress Syndrome.

OBJECTIVE: To assess whether ventilator-associated lower respiratory tract infections (VA-LRTIs) are associated with mortality in critically ill patients with acute respiratory distress syndrome (ARDS). MATERIALS AND METHODS: Post hoc analysis of prospective cohort study including mechanically ventilated patients from a multicenter prospective observational study (TAVeM study); VA-LRTI was defined as either ventilator-associated tracheobronchitis (VAT) or ventilator-associated pneumonia (VAP) based on clinical criteria and microbiological confirmation. Association between intensive care unit (ICU) mortality in patients having ARDS with and without VA-LRTI was assessed through logistic regression controlling for relevant confounders. Association between VA-LRTI and duration of mechanical ventilation and ICU stay was assessed through competing risk analysis. Contribution of VA-LRTI to a mortality model over time was assessed through sequential random forest models. RESULTS: The cohort included 2960 patients of which 524 fulfilled criteria for ARDS; 21% had VA-LRTI (VAT = 10.3% and VAP = 10.7%). After controlling for illness severity and baseline health status, we could not find an association between VA-LRTI and ICU mortality (odds ratio: 1.07; 95% confidence interval: 0.62-1.83; P = .796); VA-LRTI was also not associated with prolonged ICU length of stay or duration of mechanical ventilation. The relative contribution of VA-LRTI to the random forest mortality model remained constant during time. The attributable VA-LRTI mortality for ARDS was higher than the attributable mortality for VA-LRTI alone. CONCLUSION: After controlling for relevant confounders, we could not find an association between occurrence of VA-LRTI and ICU mortality in patients with ARDS.

Regular consumption of soft drinks is associated with type 2 diabetes incidence in Mexican adults: findings from a prospective cohort study.

BACKGROUND: Although high consumption of soft drinks has been associated with excess of type 2 diabetes risk, the strength of this association in the Mexican population, where a type 2 diabetes genetic susceptibility has been well established, has been scarcely studied. This study aimed to estimate the risk of type 2 diabetes due to soft drinks consumption in a cohort of Mexicans. METHODS: We used data on 1445 participants from the Health Workers Cohort Study, a prospective cohort conducted in Cuernavaca, Mexico. Soft drinks consumption was assessed with a semi-quantitative 116-item food frequency questionnaire. Incident type 2 diabetes was defined as self-report of physician-diagnosed type 2 diabetes, fasting glucose > 126 mg/dl, or hypoglycemic medication at any examination. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazard models. RESULTS: With a total of 9526.2 person-years of follow-up, 109 incident cases of type 2 diabetes were observed. Type 2 diabetes incidence rate was 7.6, 11.0, and 17.1 per 1000 person-years across levels of soft drinks consumption of < 1, 1-4, and ≥ 5 servings/week, respectively (p < 0.001 for trend). The intake of ≥5 soft drinks/week was significantly associated with an increased risk of type 2 diabetes (HR 1.9 95% CI:1.0-3.5) compared with consumption of < 1/week (p-trend = 0.040). The HR was attenuated by further adjustment for body mass index (HR 1.5 95%CI:0.8-2.8) and abdominal obesity (HR 1.6 95%CI:0.8-3.0). CONCLUSIONS: The consumption of soft drinks was associated with a higher risk of type 2 diabetes in a cohort of Mexican adults. Our results further support recommendations to limit soft drinks intake to address the growing diabetes epidemic in Mexico.

Contribution of KCNQ and TREK Channels to the Resting Membrane Potential in Sympathetic Neurons at Physiological Temperature.

The ionic mechanisms controlling the resting membrane potential (RMP) in superior cervical ganglion (SCG) neurons have been widely studied and the M-current (IM, KCNQ) is one of the key players. Recently, with the discovery of the presence of functional TREK-2 (TWIK-related K+ channel 2) channels in SCG neurons, another potential main contributor for setting the value of the resting membrane potential has appeared. In the present work, we quantified the contribution of TREK-2 channels to the resting membrane potential at physiological temperature and studied its role in excitability using patch-clamp techniques. In the process we have discovered that TREK-2 channels are sensitive to the classic M-current blockers linopirdine and XE991 (IC50 = 0.310 ± 0.06 µM and 0.044 ± 0.013 µM, respectively). An increase from room temperature (23 °C) to physiological temperature (37 °C) enhanced both IM and TREK-2 currents. Likewise, inhibition of IM by tetraethylammonium (TEA) and TREK-2 current by XE991 depolarized the RMP at room and physiological temperatures. Temperature rise also enhanced adaptation in SCG neurons which was reduced due to TREK-2 and IM inhibition by XE991 application. In summary, TREK-2 and M currents contribute to the resting membrane potential and excitability at room and physiological temperature in the primary culture of mouse SCG neurons.

PIP2 Mediated Inhibition of TREK Potassium Currents by Bradykinin in Mouse Sympathetic Neurons.

Bradykinin (BK), a hormone inducing pain and inflammation, is known to inhibit potassium M-currents (IM) and to increase the excitability of the superior cervical ganglion (SCG) neurons by activating the Ca2+-calmodulin pathway. M-current is also reduced by muscarinic agonists through the depletion of membrane phosphatidylinositol 4,5-biphosphate (PIP2). Similarly, the activation of muscarinic receptors inhibits the current through two-pore domain potassium channels (K2P) of the "Tandem of pore-domains in a Weakly Inward rectifying K+ channel (TWIK)-related channels" (TREK) subfamily by reducing PIP2 in mouse SCG neurons (mSCG). The aim of this work was to test and characterize the modulation of TREK channels by bradykinin. We used the perforated-patch technique to investigate riluzole (RIL) activated currents in voltage- and current-clamp experiments. RIL is a drug used in the palliative treatment of amyotrophic lateral sclerosis and, in addition to blocking voltage-dependent sodium channels, it also selectively activates the K2P channels of the TREK subfamily. A cell-attached patch-clamp was also used to investigate TREK-2 single channel currents. We report here that BK reduces spike frequency adaptation (SFA), inhibits the riluzole-activated current (IRIL), which flows mainly through TREK-2 channels, by about 45%, and reduces the open probability of identified single TREK-2 channels in cultured mSCG cells. The effect of BK on IRIL was precluded by the bradykinin receptor (B2R) antagonist HOE-140 (d-Arg-[Hyp3, Thi5, d-Tic7, Oic8]BK) but also by diC8PIP2 which prevents PIP2 depletion when phospholipase C (PLC) is activated. On the contrary, antagonizing inositol triphosphate receptors (IP3R) using 2-aminoethoxydiphenylborane (2-APB) or inhibiting protein kinase C (PKC) with bisindolylmaleimide did not affect the inhibition of IRIL by BK. In conclusion, bradykinin inhibits TREK-2 channels through the activation of B2Rs resulting in PIP2 depletion, much like we have demonstrated for muscarinic agonists. This mechanism implies that TREK channels must be relevant for the capture of information about pain and visceral inflammation.

Design of hybrid protein-coated magnetic core-mesoporous silica shell nanocomposites for MRI and drug release assessed in a 3D tumor cell model.

In this work, we describe the design and the use of a novel theranostic hybrid nanocomposite made of an iron oxide core and a mesoporous silica shell (IO@MS) of ca. 30 nm coated by human serum albumin (HSA) layer for magnetic resonance imaging and drug delivery applications. The porosity of IO@MS nanoparticles was loaded with an antitumoral drug, Doxorubicin (Dox) reaching a high drug loading capacity (DLC) of 34 w%. To entrap the drug, a tight HSA coating held via isobutyramide (IBAM) binders was deposited. We show that this protein nanoassembly entraps the drugs efficiently and behaves as an innovative enzyme-sensitive gatekeeper that is degraded upon protease action. Finally we assess the Dox release in a 3D cell model via confocal imaging and its cytotoxicity is shown by growth inhibition studies on liver cancer cell spheroids.