Heart and lung aquaporins play a major role in severity of heart failure with preserved ejection fraction in mice and differs between comorbidities

Introduction

Heart failure (HF) is a major public health problem worldwide. To date, HF with preserved ejection fraction (EF, HFpEF) represents half of all HF patients and its prevalence is increasing. HFpEF is associated with multiple comorbidities, including diabetes mellitus, pulmonary and systemic hypertension and obesity, mainly in elderly population. Accurately phenotyping HFpEF is crucial for the development of new therapies, appropriate patient stratification and the implementation of a personalised medicine. Cardiac and pulmonary remodelling play a major role in HFpEF severity but the specific mechanisms underlying cardiac failure and lung congestion, the last stage in HFpEF, in each comorbidity are incompletely understood, precluding the development of effective therapies. Aquaporins (AQP) are membrane proteins serving as water channels across the plasma membrane and control intra- and extracellular fluid volume and prompt to tissue oedema in many organs. However, its specific contribution in HFpEF has not been explored.

Purpose

We aimed to identify cardiac and pulmonary molecular changes associated to dysfunction and oedema in HFpEF, specific for each comorbidity.

Methods

A total of 48 C57BL/6 mice 10 weeks old were randomised to the following groups: control (Ctl; n=9), type I diabetes (Db; n=9), chronic hypoxia (PAH; n=10), obesity (Ob; n=10) and systemic arterial hypertension (SAH; n=10). Mice were followed for up to 2.5 years by echocardiography and lung ultrasound until they developed pulmonary oedema (HF) or died naturally. Lungs and heart were extracted and changes were determined by proteomic, immunohistochemistry and qRT-PCR.

Results

Diastolic dysfunction was observed in all comorbidities and above 50% of those mice developed HF. Db presented the highest ratio in developing HF. Db also showed the earliest mortality (47 weeks), whereas PAH, Ob and SAH mice survived for 82, 92 and 99 weeks, respectively (p<0.001 vs Ctl). A common finding in all groups was the development of different degrees o perivascular fibrosis. Db mice, the HFpEF severest group, showed an increase in pulmonary AQP1 and 5 (p<0.05 and p<0.001, respectively, vs Ctl). Upregulation of AQPs correlated with increased ventricular filling pressures (E/E', r2=07). Cardiac AQP4 was also markedly elevated in Db mice in left and right ventricle (p<0.001 and p=0.01, respectively, vs Ctl).

Conclusion

Increased AQPs in the lung is associated with a more aggressive development of congestion and HFpEF. In addition, increased AQP4 in the heart in the most aggressive form of HFpEF suggests a relevant role in cardiac oedema. Targeting AQPs in HFpEF may prevent oedema and decompensation.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): This study was supported from the Spanish Ministerio de Economía y Competitividad (RTI2018-096961-B-I00, SAF2015-65722-R and SAF2012-31451 to E.L-P. and Juan de la Cierva Incorporaciόn to M,V-O). The CNIC is supported by the Ministerio de Ciencia, Innovaciόn y Universidades (MCNU) and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence (SEV-2015-0505).

Habitability: A Review

Habitability is a widely used word in the geoscience, planetary science, and astrobiology literature, but what does it mean? In this review on habitability, we define it as the ability of an environment to support the activity of at least one known organism. We adopt a binary definition of "habitability" and a "habitable environment." An environment either can or cannot sustain a given organism. However, environments such as entire planets might be capable of supporting more or less species diversity or biomass compared with that of Earth. A clarity in understanding habitability can be obtained by defining instantaneous habitability as the conditions at any given time in a given environment required to sustain the activity of at least one known organism, and continuous planetary habitability as the capacity of a planetary body to sustain habitable conditions on some areas of its surface or within its interior over geological timescales. We also distinguish between surface liquid water worlds (such as Earth) that can sustain liquid water on their surfaces and interior liquid water worlds, such as icy moons and terrestrial-type rocky planets with liquid water only in their interiors. This distinction is important since, while the former can potentially sustain habitable conditions for oxygenic photosynthesis that leads to the rise of atmospheric oxygen and potentially complex multicellularity and intelligence over geological timescales, the latter are unlikely to. Habitable environments do not need to contain life. Although the decoupling of habitability and the presence of life may be rare on Earth, it may be important for understanding the habitability of other planetary bodies.

Mars Science Laboratory relative humidity observations: Initial results

The Mars Science Laboratory (MSL) made a successful landing at Gale crater early August 2012. MSL has an environmental instrument package called the Rover Environmental Monitoring Station (REMS) as a part of its scientific payload. REMS comprises instrumentation for the observation of atmospheric pressure, temperature of the air, ground temperature, wind speed and direction, relative humidity (REMS-H), and UV measurements. We concentrate on describing the REMS-H measurement performance and initial observations during the first 100 MSL sols as well as constraining the REMS-H results by comparing them with earlier observations and modeling results. The REMS-H device is based on polymeric capacitive humidity sensors developed by Vaisala Inc., and it makes use of transducer electronics section placed in the vicinity of the three humidity sensor heads. The humidity device is mounted on the REMS boom providing ventilation with the ambient atmosphere through a filter protecting the device from airborne dust. The final relative humidity results appear to be convincing and are aligned with earlier indirect observations of the total atmospheric precipitable water content. The water mixing ratio in the atmospheric surface layer appears to vary between 30 and 75 ppm. When assuming uniform mixing, the precipitable water content of the atmosphere is ranging from a few to six precipitable micrometers.

KEY POINTS

Atmospheric water mixing ratio at Gale crater varies from 30 to 140 ppmMSL relative humidity observation provides good dataHighest detected relative humidity reading during first MSL 100 sols is RH75.

Mars Science Laboratory relative humidity observations: Initial results

The Mars Science Laboratory (MSL) made a successful landing at Gale crater early August 2012. MSL has an environmental instrument package called the Rover Environmental Monitoring Station (REMS) as a part of its scientific payload. REMS comprises instrumentation for the observation of atmospheric pressure, temperature of the air, ground temperature, wind speed and direction, relative humidity (REMS-H), and UV measurements. We concentrate on describing the REMS-H measurement performance and initial observations during the first 100 MSL sols as well as constraining the REMS-H results by comparing them with earlier observations and modeling results. The REMS-H device is based on polymeric capacitive humidity sensors developed by Vaisala Inc., and it makes use of transducer electronics section placed in the vicinity of the three humidity sensor heads. The humidity device is mounted on the REMS boom providing ventilation with the ambient atmosphere through a filter protecting the device from airborne dust. The final relative humidity results appear to be convincing and are aligned with earlier indirect observations of the total atmospheric precipitable water content. The water mixing ratio in the atmospheric surface layer appears to vary between 30 and 75 ppm. When assuming uniform mixing, the precipitable water content of the atmosphere is ranging from a few to six precipitable micrometers.

KEY POINTS

Atmospheric water mixing ratio at Gale crater varies from 30 to 140 ppmMSL relative humidity observation provides good dataHighest detected relative humidity reading during first MSL 100 sols is RH75.