Piezo1 channels are mechanosensors in human fetoplacental endothelial cells

STUDY QUESTION

Does the shear stress sensing ion channel subunit Piezo1 have an important mechanotransduction role in human fetoplacental endothelium?

SUMMARY ANSWER

Piezo1 is present and functionally active in human fetoplacental endothelial cells, and disruption of Piezo1 prevents the normal response to shear stress.

WHAT IS KNOWN ALREADY

Shear stress is an important stimulus for maturation and function of placental vasculature but the molecular mechanisms by which the force is detected and transduced are unclear. Piezo1 channels are Ca²⁺-permeable non-selective cationic channels which are critical for shear stress sensing and maturation of murine embryonic vasculature.

STUDY DESIGN, SAMPLES/MATERIALS, METHODS

We investigated the relevance of Piezo1 to placental vasculature by studying human fetoplacental endothelial cells (FpECs) from healthy pregnancies. Endothelial cells were isolated from placental cotyledons and cultured, for the study of tube formation and cell alignment to shear stress. In addition, human placental arterial endothelial cells were isolated and studied immediately by patch-clamp electrophysiology.

MAIN RESULTS AND THE ROLE OF CHANCE

The synthetic Piezo1 channel agonist Yoda1 caused strong elevation of the intracellular Ca²⁺ concentration with a 50% effect occurring at about 5.4 μM. Knockdown of Piezo1 by RNA interference suppressed the Yoda1 response, consistent with it being mediated by Piezo1 channels. Alignment of cells to the direction of shear stress was also suppressed by Piezo1 knockdown without loss of cell viability. Patch-clamp recordings from freshly isolated endothelium showed shear stress-activated single channels which were characteristic of Piezo1.

LIMITATIONS, REASONS FOR CAUTION

The in vitro nature of fetoplacental endothelial cell isolation and subsequent culture may affect FpEC characteristics and PIEZO1 expression. In addition to Piezo1, alternative shear stress sensing mechanisms have been suggested in other systems and might also contribute in the placenta.

WIDER IMPLICATIONS OF THE FINDINGS

These data suggest that Piezo1 is an important molecular determinant of blood flow sensitivity in the placenta. Establishing and manipulating the molecular mechanisms regulating shear stress sensing could lead to novel therapeutic strategies to improve blood flow in the placenta.

LARGE-SCALE DATA

Not applicable.

STUDY FUNDING/COMPETING INTEREST(S)

LCM was funded by a Clinical Research Training Fellowship from the Medical Research Council and by the Royal College of Obstetricians and Gynaecologists, and has received support from a Wellcome Trust Institutional Strategic Support Fund. JS was supported by the Wellcome Trust and a BHF Intermediate Research Fellowship. HJG, CW, AJH and PJW were supported by PhD Studentships from BHF, BBSRC and the Leeds Teaching Hospitals Charitable Foundation respectively. All authors declare no conflict of interest.

Candida auris exhibits resilient biofilm characteristics in vitro: implications for environmental persistence

Surfaces within healthcare play a key role in the transmission of drug-resistant pathogens. Candida auris is an emerging multidrug-resistant yeast which can survive for prolonged periods on environmental surfaces. Here we show that the ability to form cellular aggregates increases survival after 14 days, which coincides with the upregulation of biofilm-associated genes. Additionally, the aggregating strain demonstrated tolerance to clinical concentrations of sodium hypochlorite and remained viable 14 days post treatment. The ability of C. auris to adhere to and persist on environmental surfaces emphasizes our need to better understand the biology of this fungal pathogen.

Retinal burns from laser pointers: a risk in children with behavioural problems

OBJECTIVE

To explore self-inflicted retinal burns from laser pointers in children.

METHODS

Literature review of laser pointer retinal injuries in childhood and online survey of UK Consultant Ophthalmologists. A cohort of local children with self-inflicted injury is described. The matter is topical. We review progress in recent legislation and policy change in the UK.

RESULTS

Four of 77 case reports of laser burns in childhood analysed reported psychological or behavioural issues. Three of four children in our cohort had such issues. Delay in diagnosis occurred in two of our patients. Structural retinal damage persisted for over 12 months in all four children (seven eyes). Our survey of UK ophthalmologists found 159 cases of injury (85% male), 80% under 20 years of age. The majority of the laser pointers were purchased online. Many patients (36%) suffered moderate vision loss (6/18 to 6/60 Snellen), while 17% (at least 11 patients) suffered severe vision loss (<6/60 Snellen).

CONCLUSION

We highlight the risk of macular damage and vision loss from handheld lasers specifically in children with behavioural, learning or mental health issues. The diagnosis may be difficult or delayed in such children. In children with uncertain macular changes, ophthalmologists should explore the history for possible instances of exposure to handheld lasers pointers. Regulatory authorities and manufacturers of handheld lasers need to be aware of the risk to children. Furthermore, there is a need to better inform parents, carers and teachers of the risk of ocular self-injury from such lasers pointers.

A Statewide Survey of Container Aedes Mosquitoes (Diptera: Culicidae) in North Carolina, 2016: A Multiagency Surveillance Response to Zika Using Ovitraps

Native and invasive container-inhabiting Aedes mosquitoes (Diptera: Culicidae) play important roles in the transmission of endemic and traveler-introduced arboviruses in the United States. In response to the emergence of Zika virus into the Americas, we surveyed the distribution of container Aedes spp. of public health importance within North Carolina during 2016 using ovitraps. A seasonal survey was conducted in 18 counties from the mountains to the coast to identify species incriminated in the transmission of chikungunya, dengue, La Crosse, yellow fever, and Zika viruses. Multiple local, state, and federal agencies participated in the study and submitted more than 3,600 ovistrips. Aedes albopictus (Skuse) (81.4%, n = 54,458) was the most common and widespread species found in this survey, followed by Aedes triseriatus (Say) (10.7%, n = 7,169) and Aedes japonicus (Theobald) (7.9%, n = 5,262). We did not find Aedes aegypti and rarely found Aedes hendersoni (Cockerell). We assessed broad-scale climatic and other factors and determined that longitude, elevation, rainfall, and temperature had significant effects on explaining the variation in presence, abundance, and phenology of container Aedes in North Carolina. However, much of the variation in these outcomes was not explained at this coarse scale and may benefit from finer-scale analyses. These efforts represent the largest ovitrap survey ever conducted in the state.

Patterns of kidney injury in pediatric nonkidney solid organ transplant recipients

The incidence of acute kidney injury (AKI) and its impact on chronic kidney disease (CKD) following pediatric nonkidney solid organ transplantation is unknown. We aimed to determine the incidence of AKI and CKD and examine their relationship among children who received a heart, lung, liver, or multiorgan transplant at the Hospital for Sick Children between 2002 and 2011. AKI was assessed in the first year posttransplant. Among 303 children, perioperative AKI (within the first week) occurred in 67% of children, and AKI after the first week occurred in 36%, with the highest incidence among lung and multiorgan recipients. Twenty-three children (8%) developed CKD after a median follow-up of 3.4 years. Less than 5 children developed end-stage renal disease, all within 65 days posttransplant. Those with 1 AKI episode by 3 months posttransplant had significantly greater risk for developing CKD after adjusting for age, sex, and estimated glomerular filtration rate at transplant (hazard ratio: 2.77, 95% confidence interval, 1.13-6.80, P trend = .008). AKI is common in the first year posttransplant and associated with significantly greater risk of developing CKD. Close monitoring for kidney disease may allow for earlier implementation of kidney-sparing strategies to decrease risk for progression to CKD.

Oxidative Stress and Cardiovascular Risk in Type 1 Diabetes Mellitus: Insights From the DCCT/EDIC Study

Background

Hyperglycemia leading to increased oxidative stress is implicated in the increased risk for the development of macrovascular and microvascular complications in patients with type 1 diabetes mellitus.

Methods and Results

A random subcohort of 349 participants was selected from the DCCT / EDIC (Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications) cohort. This included 320 controls and 29 cardiovascular disease cases that were augmented with 98 additional known cases to yield a case cohort of 447 participants (320 controls, 127 cases). Biosamples from DCCT baseline, year 1, and closeout of DCCT , and 1 to 2 years post‐ DCCT ( EDIC years 1 and 2) were measured for markers of oxidative stress, including plasma myeloperoxidase, paraoxonase activity, urinary F 2α isoprostanes, and its metabolite, 2,3 dinor‐8 iso prostaglandin F 2α . Following adjustment for glycated hemoblobin and weighting the observations inversely proportional to the sampling selection probabilities, higher paraoxonase activity, reflective of antioxidant activity, and 2,3 dinor‐8 iso prostaglandin F 2α , an oxidative marker, were significantly associated with lower risk of cardiovascular disease (−4.5% risk for 10% higher paraoxonase, P <0.003; −5.3% risk for 10% higher 2,3 dinor‐8 iso prostaglandin F 2α , P =0.0092). In contrast, the oxidative markers myeloperoxidase and F 2α isoprostanes were not significantly associated with cardiovascular disease after adjustment for glycated hemoblobin. There were no significant differences between DCCT intensive and conventional treatment groups in the change in all biomarkers across time segments.

Conclusions

Heightened antioxidant activity (rather than diminished oxidative stress markers) is associated with lower cardiovascular disease risk in type 1 diabetes mellitus, but these biomarkers did not change over time with intensification of glycemic control.

Clinical Trial Registration

URL : https://www.clinicaltrials.gov . Unique identifiers: NCT 00360815 and NCT 00360893.