Screening and management of hypertensive patients with chronic kidney disease referred to Hypertension Excellence Centres among 27 countries. A pilot survey based on questionnaire.

OBJECTIVE: Real-life management of hypertensive patients with chronic kidney disease (CKD) is unclear. METHODS: A survey was conducted in 2023 by the European Society of Hypertension (ESH) to assess management of CKD patients referred to ESH-Hypertension Excellence Centres (ESH-ECs) at first referral visit. The questionnaire contained 64 questions with which ESH-ECs representatives were asked to estimate preexisting CKD management quality. RESULTS: Overall, 88 ESH-ECs from 27 countries participated (fully completed surveys: 66/88 [75.0%]). ESH-ECs reported that 28% (median, interquartile range: 15-50%) had preexisting CKD, with 10% of them (5-30%) previously referred to a nephrologist, while 30% (15-40%) had resistant hypertension. The reported rate of previous recent (<6 months) estimated glomerular filtration rate (eGFR) and urine albumin-creatinine ratio (UACR) testing were 80% (50-95%) and 30% (15-50%), respectively. The reported use of renin-angiotensin system blockers was 80% (70-90%). When a nephrologist was part of the ESH-EC teams the reported rates SGLT2 inhibitors (27.5% [20-40%] vs. 15% [10-25], P = 0.003), GLP1-RA (10% [10-20%] vs. 5% [5-10%], P = 0.003) and mineralocorticoid receptor antagonists (20% [10-30%] vs. 15% [10-20%], P = 0.05) use were greater as compared to ESH-ECs without nephrologist participation. The rate of reported resistant hypertension, recent eGFR and UACR results and management of CKD patients prior to referral varied widely across countries. CONCLUSIONS: Our estimation indicates deficits regarding CKD screening, use of nephroprotective drugs and referral to nephrologists before referral to ESH-ECs but results varied widely across countries. This information can be used to build specific programs to improve care in hypertensives with CKD.

Molecular mechanisms underlying TNFα-induced mitochondrial fragmentation in human airway smooth muscle cells.

Tumor necrosis factor α (TNFα), a proinflammatory cytokine, plays a significant role in mediating the effects of acute inflammation in response to allergens, pollutants, and respiratory infections. Previously, we showed that acute exposure to TNFα induces mitochondrial fragmentation in human airway smooth muscle (hASM) cells, which is associated with increased expression of dynamin-related protein 1 (DRP1). Phosphorylation of DRP1 at serine 616 (pDRP1S616) promotes its translocation and binding to the outer mitochondrial membrane (OMM) and mediates mitochondrial fragmentation. Previously, we reported that TNFα exposure triggers protein unfolding and triggers an endoplasmic reticulum (ER) stress response involving phosphorylation of inositol-requiring enzyme 1α (pIRE1α) at serine 724 (pIRE1αS724) and subsequent splicing of X-box binding protein 1 (XBP1s) in hASM cells. We hypothesize that TNFα-mediated activation of the pIRE1αS724/XBP1s ER stress pathway in hASM cells transcriptionally activates genes that encode kinases responsible for pDRP1S616 phosphorylation. Using 3-D confocal imaging of MitoTracker green-labeled mitochondria, we found that TNFα treatment for 6 h induces mitochondrial fragmentation in hASM cells. We also confirmed that 6 h TNFα treatment activates the pIRE1α/XBP1s ER stress pathway. Using in silico analysis and ChIP assay, we showed that CDK1 and CDK5, kinases involved in the phosphorylation of pDRP1S616, are transcriptionally targeted by XBP1s. TNFα treatment increased the binding affinity of XBP1s on the promoter regions of CDK1 and CDK5, and this was associated with an increase in pDRP1S616 and mitochondria fragmentation. This study reveals a new underlying molecular mechanism for TNFα-induced mitochondrial fragmentation in hASM cells.NEW & NOTEWORTHY Airway inflammation is increasing worldwide. Proinflammatory cytokines mediate an adaptive mechanism to overcome inflammation-induced cellular stress. Previously, we reported that TNFα mediates hASM cellular responses, leading to increased force and ATP consumption associated with increased O2 consumption, and oxidative stress. This study indicates that TNFα induces ER stress, which induces mitochondrial fragmentation via pIRE1αS724/XBP1s mediated CDK1/5 upregulation and pDRP1S616 phosphorylation. Mitochondrial fragmentation may promote hASM mitochondrial biogenesis to maintain healthy mitochondrial pool.

Chemical Chaperone 4-PBA Mitigates Tumor Necrosis Factor Alpha-Induced Endoplasmic Reticulum Stress in Human Airway Smooth Muscle.

Airway inflammation and pro-inflammatory cytokines such as tumor necrosis factor alpha (TNFα) underlie the pathophysiology of respiratory diseases, including asthma. Previously, we showed that TNFα activates the inositol-requiring enzyme 1α (IRE1α)/X-box binding protein 1 spliced (XBP1s) endoplasmic reticulum (ER) stress pathway in human airway smooth muscle (hASM) cells. The ER stress pathway is activated by the accumulation of unfolded proteins in the ER. Accordingly, chemical chaperones such as 4-phenylbutyric acid (4-PBA) may reduce ER stress activation. In the present study, we hypothesized that chemical chaperone 4-PBA mitigates TNFα-induced ER stress in hASM cells. hASM cells were isolated from bronchiolar tissue obtained from five patients with no history of smoking or respiratory diseases. The hASM cells' phenotype was confirmed via the expression of alpha-smooth muscle actin and elongated morphology. hASM cells from the same patient sample were then separated into three 12 h treatment groups: (1) TNFα (20 ng/mL), (2) TNFα + 4-PBA (1 µM, 30 min pretreatment), and (3) untreated control. The expressions of total IRE1α and phosphorylated IRE1α (pIRE1αS724) were determined through Western blotting. The splicing of XBP1 mRNA was analyzed using RT-PCR. We found that TNFα induced an increase in pIRE1αS724 phosphorylation, which was mitigated by treatment with chemical chaperone 4-PBA. We also found that TNFα induced an increase in XBP1s mRNA, which was also mitigated by treatment with chemical chaperone 4-PBA. These results support our hypothesis and indicate that chemical chaperone 4-PBA treatment mitigates TNFα-induced ER stress in hASM cells.

Cell-Based Measurement of Mitochondrial Function in Human Airway Smooth Muscle Cells.

Cellular mitochondrial function can be assessed using high-resolution respirometry that measures the O2 consumption rate (OCR) across a number of cells. However, a direct measurement of cellular mitochondrial function provides valuable information and physiological insight. In the present study, we used a quantitative histochemical technique to measure the activity of succinate dehydrogenase (SDH), a key enzyme located in the inner mitochondrial membrane, which participates in both the tricarboxylic acid (TCA) cycle and electron transport chain (ETC) as Complex II. In this study, we determine the maximum velocity of the SDH reaction (SDHmax) in individual human airway smooth muscle (hASM) cells. To measure SDHmax, hASM cells were exposed to a solution containing 80 mM succinate and 1.5 mM nitroblue tetrazolium (NBT, reaction indicator). As the reaction proceeded, the change in optical density (OD) due to the reduction of NBT to its diformazan (peak absorbance wavelength of 570 nm) was measured using a confocal microscope with the pathlength for light absorbance tightly controlled. SDHmax was determined during the linear period of the SDH reaction and expressed as mmol fumarate/liter of cell/min. We determine that this technique is rigorous and reproducible, and reliable for the measurement of mitochondrial function in individual cells.

Bioresorbable Magnesium-Based Stent: Real-World Clinical Experience and Feasibility of Follow-Up by Coronary Computed Tomography: A New Window to Look at New Scaffolds.

(1) Background: The diagnostic accuracy of coronary computed tomography angiography (CCTA) for coronary artery disease (CAD) has greatly improved so CCTA represents a transition in the care of patients suffering from CAD. Magnesium-based bioresorbable stents (Mg-BRS) secure acute percutaneous coronary intervention (PCI) results without leaving, in the long term, a metallic caging effect. The purpose of this real-world study was to assess clinical and CCTA medium- and long-term follow-up of all our patients with implanted Mg-BRS. (2) Methods: The patency of 52 Mg-BRS implanted in 44 patients with de novo lesions (24 of which had acute coronary syndrome (ACS)) was evaluated by CCTA and compared to quantitative coronary angiography (QCA) post-implantation. (3) Results: ten events including four deaths occurred during a median follow-up of 48 months. CCTA was interpretable and in-stent measurements were successful at follow-up without being hindered by the stent strut's "blooming effect". Minimal in-stent diameters on CCTA were found to be 1.03 ± 0.60 mm smaller than the expected diameter after post-dilation on implantation (p < 0.05), a difference not found in comparing CCTA and QCA. (4) Conclusions: CCTA follow-up of implanted Mg-BRS is fully interpretable and we confirm the long-term Mg-BRS safety profile.

High Fidelity Pressure Wires Provide Accurate Validation of Non-Invasive Central Blood Pressure and Pulse Wave Velocity Measurements.

Central blood pressure (cBP) is known to be a better predictor of the damage caused by hypertension in comparison with peripheral blood pressure. During cardiac catheterization, we measured cBP in the ascending aorta with a fluid-filled guiding catheter (FF) in 75 patients and with a high-fidelity micromanometer tipped wire (FFR) in 20 patients. The wire was withdrawn into the brachial artery and aorto-brachial pulse wave velocity (abPWV) was calculated from the length of the pullback and the time delay between the ascending aorta and the brachial artery pulse waves by gating to the R-wave of the ECG for both measurements. In 23 patients, a cuff was inflated around the calf and an aorta-tibial pulse wave velocity (atPWV) was calculated from the distance between the cuff around the leg and the axillary notch and the time delay between the ascending aorta and the tibial pulse waves. Brachial BP was measured non-invasively and cBP was estimated using a new suprasystolic oscillometric technology. The mean differences between invasively measured cBP by FFR and non-invasive estimation were -0.4 ± 5.7 mmHg and by FF 5.4 ± 9.4 mmHg in 52 patients. Diastolic and mean cBP were both overestimated by oscillometry, with mean differences of -8.9 ± 5.5 mmHg and -6.4 ± 5.1 mmHg compared with the FFR and -10.6 ± 6.3 mmHg and -5.9 ± 6.2 mmHg with the FF. Non-invasive systolic cBP compared accurately with the high-fidelity FFR measurements, demonstrating a low bias (≤5 mmHg) and high precision (SD ≤ 8 mmHg). These criteria were not met when using the FF measurements. Invasively derived average Ao-brachial abPWV was 7.0 ± 1.4 m/s and that of Ao-tibial atPWV was 9.1 ± 1.8 m/s. Non-invasively estimated PWV based on the reflected wave transit time did not correlate with abPWV or with atPWV. In conclusion, we demonstrate the advantages of a novel method of validation for non-invasive cBP monitoring devices using acknowledged gold standard FFR wire transducers and the possibility to easily measure PWV during coronary angiography with the impact of cardiovascular risk factors.

Molecular Mechanisms Underlying TNFα-Induced Mitochondrial Biogenesis in Human Airway Smooth Muscle.

Proinflammatory cytokines such as TNFα mediate airway inflammation. Previously, we showed that TNFα increases mitochondrial biogenesis in human ASM (hASM) cells, which is associated with increased PGC1α expression. We hypothesized that TNFα induces CREB and ATF1 phosphorylation (pCREBS133 and pATF1S63), which transcriptionally co-activate PGC1α expression. Primary hASM cells were dissociated from bronchiolar tissue obtained from patients undergoing lung resection, cultured (one-three passages), and then differentiated by serum deprivation (48 h). hASM cells from the same patient were divided into two groups: TNFα (20 ng/mL) treated for 6 h and untreated controls. Mitochondria were labeled using MitoTracker green and imaged using 3D confocal microscopy to determine mitochondrial volume density. Mitochondrial biogenesis was assessed based on relative mitochondrial DNA (mtDNA) copy number determined by quantitative real-time PCR (qPCR). Gene and/or protein expression of pCREBS133, pATF1S63, PCG1α, and downstream signaling molecules (NRFs, TFAM) that regulate transcription and replication of the mitochondrial genome, were determined by qPCR and/or Western blot. TNFα increased mitochondrial volume density and mitochondrial biogenesis in hASM cells, which was associated with an increase in pCREBS133, pATF1S63 and PCG1α expression, with downstream transcriptional activation of NRF1, NRF2, and TFAM. We conclude that TNFα increases mitochondrial volume density in hASM cells via a pCREBS133/pATF1S63/PCG1α-mediated pathway.

Effects of TNFα on Dynamic Cytosolic Ca2 + and Force Responses to Muscarinic Stimulation in Airway Smooth Muscle.

Previously, we reported that in airway smooth muscle (ASM), the cytosolic Ca2+ ([Ca2+] cyt ) and force response induced by acetyl choline (ACh) are increased by exposure to the pro-inflammatory cytokine tumor necrosis factor α (TNFα). The increase in ASM force induced by TNFα was not associated with an increase in regulatory myosin light chain (rMLC20) phosphorylation but was associated with an increase in contractile protein (actin and myosin) concentration and an enhancement of Ca2+ dependent actin polymerization. The sensitivity of ASM force generation to elevated [Ca2+] cyt (Ca2+ sensitivity) is dynamic involving both the shorter-term canonical calmodulin-myosin light chain kinase (MLCK) signaling cascade that regulates rMLC20 phosphorylation and cross-bridge recruitment as well as the longer-term regulation of actin polymerization that regulates contractile unit recruitment and actin tethering to the cortical cytoskeleton. In this study, we simultaneously measured [Ca2+] cyt and force responses to ACh and explored the impact of 24-h TNFα on the dynamic relationship between [Ca2+] cyt and force responses. The temporal delay between the onset of [Ca2+] cyt and force responses was not affected by TNFα. Similarly, the rates of rise of [Ca2+] cyt and force responses were not affected by TNFα. The absence of an impact of TNFα on the short delay relationships between [Ca2+] cyt and force was consistent with the absence of an effect of [Ca2+] cyt and force on rMLC20 phosphorylation. However, the integral of the phase-loop plot of [Ca2+] cyt and force increased with TNFα, consistent with an impact on actin polymerization and, contractile unit recruitment and actin tethering to the cortical cytoskeleton.

Dynamic cytosolic Ca2+ and force responses to muscarinic stimulation in airway smooth muscle.

During agonist stimulation of airway smooth muscle (ASM), agonists such as ACh induce a transient increase in cytosolic Ca2+ concentration ([Ca2+]cyt), which leads to a contractile response [excitation-contraction (E-C) coupling]. Previously, the sensitivity of the contractile response of ASM to elevated [Ca2+]cyt (Ca2+ sensitivity) was assessed as the ratio of maximum force to maximum [Ca2+]cyt. However, this static assessment of Ca2+ sensitivity overlooks the dynamic nature of E-C coupling in ASM. In this study, we simultaneously measured [Ca2+]cyt and isometric force responses to three concentrations of ACh (1, 2.6, and 10 µM). Both maximum [Ca2+]cyt and maximum force responses were ACh concentration dependent, but force increased disproportionately, thereby increasing static Ca2+ sensitivity. The dynamic properties of E-C coupling were assessed in several ways. The temporal delay between the onset of ACh-induced [Ca2+]cyt and onset force responses was not affected by ACh concentration. The rates of rise of the ACh-induced [Ca2+]cyt and force responses increased with increasing ACh concentration. The integral of the phase-loop plot of [Ca2+]cyt and force from onset to steady state also increased with increasing ACh concentration, whereas the rate of relaxation remained unchanged. Although these results suggest an ACh concentration-dependent increase in the rate of cross-bridge recruitment and in the rate of rise of [Ca2+]cyt, the extent of regulatory myosin light-chain (rMLC20) phosphorylation was not dependent on ACh concentration. We conclude that the dynamic properties of [Ca2+]cyt and force responses in ASM are dependent on ACh concentration but reflect more than changes in the extent of rMLC20 phosphorylation.

The European/International Fibromuscular Dysplasia Registry and Initiative (FEIRI)-clinical phenotypes and their predictors based on a cohort of 1000 patients.

AIMS: Since December 2015, the European/International Fibromuscular Dysplasia (FMD) Registry enrolled 1022 patients from 22 countries. We present their characteristics according to disease subtype, age and gender, as well as predictors of widespread disease, aneurysms and dissections. METHODS AND RESULTS: All patients diagnosed with FMD (string-of-beads or focal stenosis in at least one vascular bed) based on computed tomography angiography, magnetic resonance angiography, and/or catheter-based angiography were eligible. Patients were predominantly women (82%) and Caucasians (88%). Age at diagnosis was 46 ± 16 years (12% ≥65 years old), 86% were hypertensive, 72% had multifocal, and 57% multivessel FMD. Compared to patients with multifocal FMD, patients with focal FMD were younger, more often men, had less often multivessel FMD but more revascularizations. Compared to women with FMD, men were younger, had more often focal FMD and arterial dissections. Compared to younger patients with FMD, patients ≥65 years old had more often multifocal FMD, lower estimated glomerular filtration rate and more atherosclerotic lesions. Independent predictors of multivessel FMD were age at FMD diagnosis, stroke, multifocal subtype, presence of aneurysm or dissection, and family history of FMD. Predictors of aneurysms were multivessel and multifocal FMD. Predictors of dissections were age at FMD diagnosis, male gender, stroke, and multivessel FMD. CONCLUSIONS: The European/International FMD Registry allowed large-scale characterization of distinct profiles of patients with FMD and, more importantly, identification of a unique set of independent predictors of widespread disease, aneurysms and dissections, paving the way for targeted screening, management, and follow-up of FMD.

TNFα induces mitochondrial fragmentation and biogenesis in human airway smooth muscle.

In human airway smooth muscle (hASM), mitochondrial volume density is greater in asthmatic patients compared with normal controls. There is also an increase in mitochondrial fragmentation in hASM of moderate asthmatics associated with an increase in dynamin-related protein 1 (Drp1) and a decrease in mitofusin 2 (Mfn2) expression, mitochondrial fission, and fusion proteins, respectively. Proinflammatory cytokines such TNFα contribute to hASM hyperreactivity and cell proliferation associated with asthma. However, the involvement of proinflammatory cytokines in mitochondrial remodeling is not clearly established. In nonasthmatic hASM cells, mitochondria were labeled using MitoTracker Red and imaged in three dimensions using a confocal microscope. After 24-h TNFα exposure, mitochondria in hASM cells were more fragmented, evidenced by decreased form factor and aspect ratio and increased sphericity. Associated with increased mitochondrial fragmentation, Drp1 expression increased while Mfn2 expression was reduced. TNFα also increased mitochondrial biogenesis in hASM cells reflected by increased peroxisome proliferator-activated receptor-γ coactivator 1α expression and increased mitochondrial DNA copy number. Associated with mitochondrial biogenesis, TNFα exposure also increased mitochondrial volume density and porin expression, resulting in an increase in maximum O2 consumption rate. However, when normalized for mitochondrial volume density, O2 consumption rate per mitochondrion was reduced by TNFα exposure. Associated with mitochondrial fragmentation and biogenesis, TNFα also increased hASM cell proliferation, an effect mimicked by siRNA knockdown of Mfn2 expression and mitigated by Mfn2 overexpression. The results of this study support our hypothesis that in hASM cells exposed to TNFα mitochondria are more fragmented, with an increase in mitochondrial biogenesis and mitochondrial volume density resulting in reduced O2 consumption rate per mitochondrion.

Extramyocellular interleukin-6 influences skeletal muscle mitochondrial physiology through canonical JAK/STAT signaling pathways.

Interleukin-6 (IL-6) is a pleiotropic cytokine that has been shown to be produced acutely by skeletal muscle in response to exercise, yet chronically elevated with obesity and aging. The mechanisms by which IL-6 influences skeletal muscle mitochondria acutely and chronically are unclear. To better understand the influence of extramyocellular IL-6 on skeletal muscle mitochondrial physiology, we treated differentiated myotubes with exogenous IL-6 to evaluate the dose- and duration-dependent effects of IL-6 on salient aspects of mitochondrial biology and the role of canonical IL-6 signaling in muscle cells. Acute exposure of myotubes to IL-6 increased the mitochondrial reactive oxygen species (mtROS) production and oxygen consumption rates (JO2 ) in a manner that was dependent on activation of the JAK/STAT pathway. Furthermore, STAT3 activation by IL-6 was partly attenuated by MitoQ, a mitochondrial-targeted antioxidant, suggesting that mtROS potentiates STAT3 signaling in skeletal muscle in response to IL-6 exposure. In concert with effects on mitochondrial physiology, acute IL-6 exposure induced several mitochondrial adaptations, consistent with the stress-induced mitochondrial hyperfusion. Exposure of myotubes to chronically elevated IL-6 further increased mtROS with eventual loss of respiratory capacity. These data provide new evidence supporting the interplay between cytokine signaling and mitochondrial physiology in skeletal muscle.

COVID-19 Outbreak in a Hemodialysis Center: A Retrospective Monocentric Case Series.

BACKGROUND: The rapid worldwide spread of COVID-19 has posed a serious threat to patients treated with kidney replacement therapy (KRT). Moreover, the impact of the disease on hemodialysis centers, the patients, and the health care workers is still not completely understood. OBJECTIVE: We present the analysis of a COVID-19 outbreak in a hemodialysis center in Belgium and report the incidence, clinical course, and outcome of the disease. DESIGN: A retrospective cross-sectional cohort study. SETTING: A hemodialysis center during the COVID-19 outbreak. PATIENTS: A total of 62 patients on maintenance hemodialysis at a tertiary care center in Belgium attended by 26 health care workers. MEASUREMENTS: Baseline patients' characteristics were retrieved. The incidence, clinical course, and outcome were reported. The differences between COVID-19 survivors and nonsurvivors were assessed along with the differences between COVID-19-hospitalized and nonhospitalized patients. The incidence of the disease and outcome of health care workers were also reported. METHODS: Proportions for categorical variables were compared using the Fisher exact test and χ2. The Mann-Whitney rank sum test was used to compare continuous variables. Univariate analysis and a binomial logistic regression were used to explore variables as predictors of death. RESULTS: Between March 6 and April 14, 2020, 40 of 62 (65%) patients tested positive for severe acute respiratory syndrome beta coronavirus 2 (SARS-CoV-2) along with 18 of 26 (69%) health care professionals. Twenty-five (63%) of the infected patients were hospitalized with a median time for hospitalization-to-discharge of 8 (interquartile range [IQR] = 4-12) days. Eleven (28%) COVID-19-related deaths were recorded with a median time for onset of symptoms-to-death of 9 (IQR = 5-14) days. Lymphocytopenia was prevalent among the cohort and was found in 9 of 11 (82%) reported deaths (P = .4). There was no influence of the use of angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers on COVID-19-related deaths (P = .3). Advanced age, cardiovascular disease (CVD), and obstructive sleep apnea syndrome were all found to be significantly related to death. Of the 18 infected health care professionals, 13 (72%) were symptomatic and 2 (11%) were hospitalized. There was no reported death among the health care workers. LIMITATIONS: Limited follow-up time compared with the course of the disease along with a small sample size. CONCLUSIONS: Patients treated with KRT show a high mortality rate secondary to COVID-19. CVD and age are shown to impact survival. Proactive measures must be taken to prevent the spread of the virus in such facilities. TRIAL REGISTRATION: Not applicable as this is a retrospective study.

Cytoskeletal remodeling slows cross-bridge cycling and ATP hydrolysis rates in airway smooth muscle.

During isometric activation of airway smooth muscle (ASM), cross-bridge cycling and ATP hydrolysis rates decline across time even though isometric force is sustained. Thus, tension cost (i.e., ATP hydrolysis rate per unit of force during activation) decreases with time. The "latch-state" hypothesis attributes the dynamic change in cross-bridge cycling and ATP hydrolysis rates to changes in phosphorylation of the regulatory myosin light chain (rMLC20 ). However, we previously showed that in ASM, the extent of rMLC20 phosphorylation remains unchanged during sustained isometric force. As an alternative, we hypothesized that cytoskeletal remodeling within ASM cells results in increased internal loading of contractile proteins that slows cross-bridge cycling and ATP hydrolysis rates. To test this hypothesis, we simultaneously measured isometric force and ATP hydrolysis rate in permeabilized porcine ASM strips activated by Ca2+ (pCa 4.0). The extent of rMLC20 phosphorylation remained unchanged during isometric activation, even though ATP hydrolysis rate (tension cost) declined with time. The effect of cytoskeletal remodeling was assessed by inhibiting actin polymerization using Cytochalasin D (Cyto-D). In Cyto-D treated ASM, isometric force was reduced while ATP hydrolysis rate increased compared to untreated ASM strips. These results indicate that external transmission of force, cross-bridge cycling and ATP hydrolysis rates are affected by internal loading of contractile proteins.

Pregnancy-Related Complications in Patients With Fibromuscular Dysplasia: A Report From the European/International Fibromuscular Dysplasia Registry.

Current literature suggests a higher risk of pregnancy-related complications in patients with renal fibromuscular dysplasia (FMD). The aim of our study was to assess the nature and prevalence of pregnancy-related complications in patients subsequently diagnosed with FMD. A call for participation was sent to centers contributing to the European/International FMD Registry. Patients with at least 1 pregnancy were included. Data on pregnancy were collected through medical files and FMD characteristics through the European/International FMD Registry. Data from 534 pregnancies were obtained in 237 patients. Despite the fact that, in 96% of cases, FMD was not diagnosed before pregnancy, 40% of women (n=93) experienced pregnancy-related complications, mostly gestational hypertension (25%) and preterm birth (20%), while preeclampsia was reported in only 7.5%. Only 1 patient experienced arterial dissection and another patient an aneurysm rupture. When compared with patients without pregnancy-related complications, patients with complicated pregnancies were younger at FMD diagnosis (43 versus 51 years old; P<0.001) and had a lower prevalence of cerebrovascular FMD (30% versus 52%; P=0.003) but underwent more often renal revascularization (63% versus 40%, P<0.001). In conclusion, the prevalence of pregnancy-related complications such as gestational hypertension and preterm birth was high in patients with FMD, probably related to the severity of renal FMD. However, the prevalence of preeclampsia and arterial complications was low/moderate. These findings emphasize the need to screen hypertensive women for FMD to ensure revascularization before pregnancy if indicated and appropriate follow-up during pregnancy, without discouraging patients with FMD from considering pregnancy.

TNFα selectively activates the IRE1α/XBP1 endoplasmic reticulum stress pathway in human airway smooth muscle cells.

Airway inflammation is a key aspect of diseases such as asthma. Proinflammatory cytokines such as TNFα mediate the inflammatory response. In various diseases, inflammation leads to endoplasmic reticulum (ER) stress, the accumulation of unfolded proteins, which triggers homeostatic responses to restore normal cellular function. We hypothesized that TNFα triggers ER stress through an increase in reactive oxygen species generation in human airway smooth muscle (hASM) with a downstream effect on mitofusin 2 (Mfn2). In hASM cells isolated from lung specimens incidental to patient surgery, dose- and time-dependent effects of TNFα exposure were assessed. Exposure of hASM to tunicamycin was used as a positive control. Tempol (500 µM) was used as superoxide scavenger. Activation of three ER stress pathways were evaluated by Western blotting: 1) autophosphorylation of inositol-requiring enzyme1 (IRE1α) leading to splicing of X-box binding protein 1 (XBP1); 2) autophosphorylation of protein kinase RNA-like endoplasmic reticulum kinase (PERK) leading to phosphorylation of eukaryotic initiation factor 2α; and 3) translocation and cleavage of activating transcription factor 6 (ATF6). We found that exposure of hASM cells to tunicamycin activated all three ER stress pathways. In contrast, TNFα selectively activated the IRE1α/XBP1 pathway in a dose- and time-dependent fashion. Our results indicate that TNFα does not activate the PERK and ATF6 pathways. Exposure of hASM cells to TNFα also decreased Mfn2 protein expression. Concurrent exposure to TNFα and tempol reversed the effect of TNFα on IRE1α phosphorylation and Mfn2 protein expression. Selective activation of the IRE1α/XBP1 pathway in hASM cells after exposure to TNFα may reflect a unique homeostatic role of this pathway in the inflammatory response of hASM cells.

Inflammation-Induced Protein Unfolding in Airway Smooth Muscle Triggers a Homeostatic Response in Mitochondria.

The effects of airway inflammation on airway smooth muscle (ASM) are mediated by pro-inflammatory cytokines such as tumor necrosis factor alpha (TNFα). In this review article, we will provide a unifying hypothesis for a homeostatic response to airway inflammation that mitigates oxidative stress and thereby provides resilience to ASM. Previous studies have shown that acute exposure to TNFα increases ASM force generation in response to muscarinic stimulation (hyper-reactivity) resulting in increased ATP consumption and increased tension cost. To meet this increased energetic demand, mitochondrial O2 consumption and oxidative phosphorylation increases but at the cost of increased reactive oxygen species (ROS) production (oxidative stress). TNFα-induced oxidative stress results in the accumulation of unfolded proteins in the endoplasmic reticulum (ER) and mitochondria of ASM. In the ER, TNFα selectively phosphorylates inositol-requiring enzyme 1 alpha (pIRE1α) triggering downstream splicing of the transcription factor X-box binding protein 1 (XBP1s); thus, activating the pIRE1α/XBP1s ER stress pathway. Protein unfolding in mitochondria also triggers an unfolded protein response (mtUPR). In our conceptual framework, we hypothesize that activation of these pathways is homeostatically directed towards mitochondrial remodeling via an increase in peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC1α) expression, which in turn triggers: (1) mitochondrial fragmentation (increased dynamin-related protein-1 (Drp1) and reduced mitofusin-2 (Mfn2) expression) and mitophagy (activation of the Phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1)/Parkin mitophagy pathway) to improve mitochondrial quality; (2) reduced Mfn2 also results in a disruption of mitochondrial tethering to the ER and reduced mitochondrial Ca2+ influx; and (3) mitochondrial biogenesis and increased mitochondrial volume density. The homeostatic remodeling of mitochondria results in more efficient O2 consumption and oxidative phosphorylation and reduced ROS formation by individual mitochondrion, while still meeting the increased ATP demand. Thus, the energetic load of hyper-reactivity is shared across the mitochondrial pool within ASM cells.

Mechanisms underlying TNFα-induced enhancement of force generation in airway smooth muscle.

Airway diseases such as asthma are triggered by inflammation and mediated by proinflammatory cytokines such as tumor necrosis factor alpha (TNFα). Our goal was to systematically examine the potential mechanisms underlying the effect of TNFα on airway smooth muscle (ASM) contractility. Porcine ASM strips were incubated for 24 h with and without TNFα. Exposure to TNFα increased maximum ASM force in response to acetylcholine (Ach), with an increase in ACh sensitivity (hyperreactivity), as reflected by a leftward shift in the dose-response curve (EC50 ). At the EC50 , the [Ca2+ ]cyt response to ACh was similar between TNFα and control ASM, while force increased; thus, Ca2+ sensitivity appeared to increase. Exposure to TNFα increased the basal level of regulatory myosin light chain (rMLC) phosphorylation in ASM; however, the ACh-dependent increase in rMLC phosphorylation was blunted by TNFα with no difference in the extent of rMLC phosphorylation at the EC50 ACh concentration. In TNFα-treated ASM, total actin and myosin heavy chain concentrations increased. TNFα exposure also enhanced the ACh-dependent polymerization of G- to F-actin. The results of this study confirm TNFα-induced hyperreactivity to ACh in porcine ASM. We conclude that the TNFα-induced increase in ASM force, cannot be attributed to an enhanced [Ca2+ ]cyt response or to an increase in rMLC phosphorylation. Instead, TNFα increases Ca2+ sensitivity of ASM force generation due to increased contractile protein content (greater number of contractile units) and enhanced cytoskeletal remodeling (actin polymerization) resulting in increased tethering of contractile elements to the cortical cytoskeleton and force translation to the extracellular matrix.

Endoplasmic Reticulum Stress and Mitochondrial Function in Airway Smooth Muscle.

Inflammatory airway diseases such as asthma affect more than 300 million people world-wide. Inflammation triggers pathophysiology via such as tumor necrosis factor α (TNFα) and interleukins (e.g., IL-13). Hypercontraction of airway smooth muscle (ASM) and ASM cell proliferation are major contributors to the exaggerated airway narrowing that occurs during agonist stimulation. An emergent theme in this context is the role of inflammation-induced endoplasmic reticulum (ER) stress and altered mitochondrial function including an increase in the formation of reactive oxygen species (ROS). This may establish a vicious cycle as excess ROS generation leads to further ER stress. Yet, it is unclear whether inflammation-induced ROS is the major mechanism leading to ER stress or the consequence of ER stress. In various diseases, inflammation leads to an increase in mitochondrial fission (fragmentation), associated with reduced levels of mitochondrial fusion proteins, such as mitofusin 2 (Mfn2). Mitochondrial fragmentation may be a homeostatic response since it is generally coupled with mitochondrial biogenesis and mitochondrial volume density thereby reducing demand on individual mitochondrion. ER stress is triggered by the accumulation of unfolded proteins, which induces a homeostatic response to alter protein balance via effects on protein synthesis and degradation. In addition, the ER stress response promotes protein folding via increased expression of molecular chaperone proteins. Reduced Mfn2 and altered mitochondrial dynamics may not only be downstream to ER stress but also upstream such that a reduction in Mfn2 triggers further ER stress. In this review, we summarize the current understanding of the link between inflammation-induced ER stress and mitochondrial function and the role played in the pathophysiology of inflammatory airway diseases.