Citations

Introduction: Acute respiratory distress syndrome (ARDS) is characterized by pulmonary edema, hypoxia and systemic inflammation. The presence and clinical implications of a high cardiac output state in patients with ARDS remain unknown given the lack of invasive hemodynamic monitoring in most patients with ARDS. Hypothesis: A subset of patients with ARDS will have high output heart failure with high cardiac output and elevated pulmonary capillary wedge pressure (PAWP) representing a unique subphenotype of ARDS. Methods: Patients from the Comparison of Two Fluid-Management Strategies in Acute Lung Injury (FACTT) Trial were stratified according to baseline cardiac output states and filling pressures: HOLHF (high-output with left heart failure) was defined as cardiac index (CI) ≥ 4 L/min/m 2 and PAWP ≥ 15 mmHg; HOnoLHF (high-output without left heart failure) as CI ≥ 4 L/min/m 2 and PAWP < 15 mmHg; and NOHO (non-high-output) as CI < 4 L/min/m 2 . Hemodynamics, oxygenation, metabolic demand (VO 2 ) and clinical outcomes were compared across groups. Results: Of the 399 patients included, high-output states were present in 52% of all patients (Figure 1). High-output cohorts demonstrated higher myocardial workload, lower systemic vascular resistance (SVR), lower pulsatile arterial load, higher VO 2 and more impaired systemic O 2 utilization despite the highest peripheral O 2 delivery compared to NOHO (Table). Among the high-output cohorts, the HOLHF cohort demonstrated higher right ventricular stroke work (25.2 ± 12.1 vs. 20.3 ± 12.3, P<0.001), worse A-a gradient (326.0 ± 136.5 vs. 276.1 ± 114.7, P=0.048) and higher VO 2 (382.3 ± 234.2 vs. 289.8 ± 171.7, P<0.001) compared to HOnoLHF. Increasing cardiac output was individually related to decreasing SVR (r=-0.742, P<0.001) and increasing VO 2 (r=0.565, P<0.001) (Figure 2). When adjusted, both variables remained strongly related to increasing cardiac output (P<0.001). There were no significant differences among the cohorts with respect to refractory hypoxia and mortality. Conclusions: High-output states in ARDS are prevalent and underrecognized. Such states appear to be driven by arterial vasodilatation and heightened VO 2 with additional manifestations of increased myocardial workload and inefficient peripheral utilization with impaired systemic O 2 utilization. Whether specific strategies to mitigate the high output state might improve gas exchange, hypoxia and outcomes in patients with HOLHF and ARDS requires further study.

Hereditary renal cystic diseases are characterized by defects in primary cilia of renal tubular epithelial cells and abnormality of tubular epithelium, which ultimately result in the development of renal cysts. However, the mechanism leading from abnormality of the tubular epithelium to cystogenesis is not well understood. In this report, we demonstrate a critical role for Robo2 in regulating epithelial development, including ciliogenesis, polarization, and differentiation. We found that Robo2 deficiency results in cystic kidneys, and the cyst cells showed defective cilia and polarity defects in tubular epithelium. The cyst cells, less than terminally differentiated, continue to proliferate. We further established that Robo2 works with p53 as well as polarity and ciliary proteins (Par3, PKCς, ZO-2, and Claudin-2) to regulate these processes. Robo2 binds to Baiap2 (also known as IRSp53) through the IRSp53/MIM homology domain in renal epithelial cells. This binding allows Robo2 to phosphorylate MDM2 at Ser166 via Baiap2 and maintain p53 homeostasis. Disruption of the Robo2-Baiap2 complex causes MDM2 to be subjected to dephosphorylation, leading to a high level of active p53, and initiated p53-mediated cellular senescence via p21 and decreased the expression of ZO-1, ZO-2, PKCς, Par3, and Claudin-2 proteins, resulting in defects in epithelial development, including ciliogenesis, polarization, and differentiation. Importantly, double knockout of Robo2 and p53 rescued all the epithelial defects in kidneys compared with those in Robo2 -knockout kidneys. Taken together, the present results demonstrate that Robo2 deficiency causes renal cystic disease, which is largely dependent on defective Robo2-Baiap2 integrated signaling in kidneys.

Abstract The low efficiency of reprogramming and genomic integration of virus vectors obscure the potential application of induced pluripotent stem (iPS) cells; therefore, identification of chemicals and cooperative factors that may improve the generation of iPS cells will be of great value. Moreover, the cellular mechanisms that limit the reprogramming efficiency need to be investigated. Through screening a chemical library, we found that two chemicals reported to upregulate E-cadherin considerably increase the reprogramming efficiency. Further study of the process indicated that E-cadherin is upregulated during reprogramming and the established iPS cells possess E-cadherin-mediated cell–cell contact, morphologically indistinguishable from embryonic stem (ES) cells. Our experiments also demonstrate that overexpression of E-cadherin significantly enhances reprogramming efficiency, whereas knockdown of endogenous E-cadherin reduces the efficiency. Consistently, abrogation of cell–cell contact by the inhibitory peptide or the neutralizing antibody against the extracellular domain of E-cadherin compromises iPS cell generation. Further mechanistic study reveals that adhesive binding activity of E-cadherin is required. Our results highlight the critical role of E-cadherin-mediated cell–cell contact in reprogramming and suggest new routes for more efficient iPS cell generation.