Extracellular vesicles (EVs) play critical roles in many health and disease states, including ischemia, inflammation, and pain, which are major concerns in the perioperative period and in critically ill patients. EVs are functionally active, nanometer-sized, membrane-bound vesicles actively secreted by all cells. Cell signaling is essential to physiological and pathological processes, and EVs have recently emerged as key players in intercellular communication. Recent studies in EV biology have improved our mechanistic knowledge of the pathophysiological processes in perioperative and critical care patients. Studies also show promise in using EVs in novel diagnostic and therapeutic clinical applications. This review considers the current advances and gaps in knowledge of EVs in the areas of ischemia, inflammation, pain, and in organ systems that are most relevant to anesthesiology, perioperative medicine, critical care, and pain management. We expect the reader will better understand the relationship between EVs and perioperative and critical care pathophysiological states and their potential use as novel diagnostic and therapeutic modalities.

Translation of preclinical treatments for ischaemia-reperfusion injury into clinical therapies has been limited by a number of factors. This review will focus on a single mode of cardiac protection related to a membrane scaffolding protein, caveolin, which regulates protective signalling as well as myocyte ultrastructure in the setting of ischaemic stress. Factors that have limited the clinical translation of protection will be considered specifically in terms of signalling and structural defects. The potential of caveolin to overcome barriers to protection with the ultimate hope of clinical translation will be discussed.

Caveolae are flask-like invaginations of the cell surface that have been identified as signaling epicenters. Within these microdomains, caveolins are structural proteins of caveolae, which are able to interact with numerous signaling molecules affecting temporal and spatial dimensions required in cardiac protection. This complex moiety is essential to the mechanisms involved in volatile anesthetics. In this review we will outline a general overview of caveolae and caveolins and their role in protective signaling with a focus on the effects of volatile anesthetics. These recent developments have allowed us to better understand the mechanistic effect of volatile anesthetics and their potential in cardiac protection.

Aims

Caveolins are structural proteins clustered in lipid-rich regions of plasma membrane involved in coordinating signal transduction in various organ systems. While caveolin-1 (Cav-1) has been shown to regulate lymphocyte activation, the role of caveolin-3 (Cav-3) in immune system signaling has not been investigated. We tested the hypothesis that Cav-3 modulates lymphocyte activation.

Main methods

Lymphocyte/leukocyte subpopulations from WT and Cav-3 mice were profiled with flow cytometry. Cytokine production in quiescent and activated splenocytes from WT and Cav-3 mice was assessed with ELISA.

Key findings

Levels of T-cells, monocytes, and natural killer cells were not different between WT and KO mice, however KO mice had lower B-cell population-percentage. Functionally, activated lymphocytes from Cav-3 KO mice demonstrated significantly reduced expression of IL-2 compared to WT, while expression of TNFα, IL-6, and IL-10 was not different. Finally, expression of IL-17 was significantly reduced in T-helper cells from KO mice, while IFNγ was not, suggesting that Cav-3 is a determinant in the development of the Th-17 subpopulation.

Significance

This study is the first to demonstrate that Cav-3 may be a novel participant in B-cell expression, T-cell cytokine production and activation of inflammation.

Type 2 diabetes (T2D) has a complex pathophysiology which makes modeling the disease difficult. We aimed to develop a novel model for simulating T2D in vitro, including hyperglycemia, hyperlipidemia, and variably elevated insulin levels targeting muscle cells. We investigated insulin resistance (IR), cellular respiration, mitochondrial morphometry, and the associated function in different T2D-mimicking conditions in rodent skeletal (C2C12) and cardiac (H9C2) myotubes. The physiological controls included 5 mM of glucose with 20 mM of mannitol as osmotic controls. To mimic hyperglycemia, cells were exposed to 25 mM of glucose. Further treatments included insulin, palmitate, or both. After short-term (24 h) or long-term (96 h) exposure, we performed radioactive glucose uptake and mitochondrial function assays. The mitochondrial size and relative frequencies were assessed with morphometric analyses using electron micrographs. C2C12 and H9C2 cells that were treated short- or long-term with insulin and/or palmitate and HG showed IR. C2C12 myotubes exposed to T2D-mimicking conditions showed significantly decreased ATP-linked respiration and spare respiratory capacity and less cytoplasmic area occupied by mitochondria, implying mitochondrial dysfunction. In contrast, the H9C2 myotubes showed elevated ATP-linked and maximal respiration and increased cytoplasmic area occupied by mitochondria, indicating a better adaptation to stress and compensatory lipid oxidation in a T2D environment. Both cell lines displayed elevated fractions of swollen/vacuolated mitochondria after T2D-mimicking treatments. Our stable and reproducible in vitro model of T2D rapidly induced IR, changes in the ATP-linked respiration, shifts in energetic phenotypes, and mitochondrial morphology, which are comparable to the muscles of patients suffering from T2D. Thus, our model should allow for the study of disease mechanisms and potential new targets and allow for the screening of candidate therapeutic compounds.

Background: Tobacco smoking is a major risk factor for cardiovascular and lung disease. Inhalation of aerosols formed by electronic nicotine delivery systems (ENDS) such as E‐cigarettes (E‐cigs) may expose the user to harms beyond those of nicotine alone. Data on the cardiovascular risks of E‐cigs and vaping devices remain inconclusive. However, exposure to E‐cigs induces the release of multiple substances, including exosomes and metabolites, into the bloodstream. There is limited information on the role of these exosomes and metabolites on cellular homeostasis. Mitochondria are highly sensitive to cigarette smoke, however E‐cig aerosol induced changes in mitochondrial function are not well studied. We investigated the effects of E‐cig plasma mediators on metabolism and function in human vascular endothelial (EA.hy 926) and lung epithelial cells (A549). Hypothesis: Plasma from E‐cig users will induce alterations in the metabolism and mitochondrial function of endothelial and lung epithelial cells. Methods: A longitudinal cohort study was conducted on subjects who exclusively used E‐cigarettes (n=21) and 10 non‐smoking, non‐vaping subjects. We included active E‐cig use without known lung disease and with normal lung function, between the ages of 18‐30 years. E‐cig use was confirmed with in‐person interviews and plasma cotinine levels. Active E‐cig use was defined as use of >0.5‐1 mL e‐liquid/day or 3.5‐7 mL/week for >6 months. Plasma was isolated and stored at ‐70°C until exosomes were profiled. The effects of E‐cig plasma (1%, 1h conditioning) mediators were assessed in vitro on endothelial cells (8x104/well) and epithelial cells (5x104/well) using the Seahorse XF Cell Mito Stress Test. Results: Results were standardized for cell number and FCCP concentrations for both EA.hy 926 and A549 cells. Maximal mitochondrial respiration and spare capacity were decreased in human vascular endothelial cells and epithelial cells treated with E‐cig plasma relative to plasma from non‐smoker/non‐vapers. Basal respiration and ATP‐linked respiration was not different after treatment with plasma from E‐cig users versus non‐smoker/non‐vapers in either cell type. Conclusions: To our knowledge, our results are the first to suggest that factors in the plasma of E‐cig users lead to reduction in maximal metabolic rates of human endothelial and lung cells in vitro. These results have important implications regarding the effects of E‐cig use on cellular metabolism and mitochondrial function and eventual public health recommendations. We are currently investigating the underlying mechanisms of action of E‐cig plasma components on mitochondrial biology.

Background

Nutritional risk and low BMI are common among community-dwelling older adults, but it is unclear what associations these factors have with health services utilization and mortality over long-term follow-up. The aim of this study was to assess prospective associations of nutritional risk and BMI with all-cause, nonsurgical, and surgical hospitalization; nursing home admission; and mortality over 8.5 years.

Methods

Data are from 1,000 participants in the University of Alabama at Birmingham Study of Aging, a longitudinal, observational study of older black and white residents of Alabama aged 65 and older. Nutritional risk was assessed using questions associated with the DETERMINE checklist. BMI was categorized as underweight (<18.5), normal weight (18.5-24.9), overweight (25.0-29.9), class I obese (30.0-34.9), and classes II and III obese (≥35.0). Cox proportional hazards models were fit to assess risk of all-cause, nonsurgical, and surgical hospitalization; nursing home admission; and mortality. Covariates included social support, social isolation, comorbidities, and demographic measures.

Results

In adjusted models, persons with high nutritional risk had 51% greater risk of all-cause hospitalization (95% confidence interval: 1.14-2.00) and 50% greater risk of nonsurgical hospitalizations (95% confidence interval: 1.11-2.01; referent: low nutritional risk). Persons with moderate nutritional risk had 54% greater risk of death (95% confidence interval: 1.19-1.99). BMI was not associated with any outcomes in adjusted models.

Conclusions

Nutritional risk was associated with all-cause hospitalizations, nonsurgical hospitalizations, and mortality. Nutritional risk may affect the disablement process that leads to health services utilization and death. These findings point to the need for more attention on nutritional assessment, interventions, and services for community-dwelling older adults.

Objectives

To determine whether cumulative symptom burden predicts hospitalization or emergency department (ED) visits in a cohort of older adults.

Design

Prospective, observational study with a baseline in-home assessment of symptom burden.

Setting

Central Alabama.

Participants

Nine hundred eighty community-dwelling adults aged 65 and older (mean 75.3 ± 6.7) recruited from a random sample of Medicare beneficiaries stratified according to sex, race, and urban/rural residence.

Measurements

Symptom burden score (range 0-10). One point was given for each symptom reported: shortness of breath, tiredness or fatigue, problems with balance or dizziness, leg weakness, poor appetite, pain, stiffness, constipation, anxiety, and loss of interest in activities. Dependent variables were hospitalizations and ED visits, assessed every 6 months during the 8.5-year follow-up period. Using Cox proportional hazards models, time from the baseline in-home assessment to the first hospitalization and first hospitalization or ED visit was determined.

Results

During the 8.5-year follow-up period, 545 (55.6%) participants were hospitalized or had an ED visit. Participants with greater symptom burden had higher risk of hospitalization (hazard ratio (HR) = 1.09, 95% confidence interval (CI) = 1.05-1.14) and hospitalization or ED visit (HR = 1.10, 95% CI = 1.06-1.14) than those with lower scores. Participants living in rural areas had significantly lower risk of hospitalization (HR = 0.83, 95% CI = 0.69-0.99) and hospitalization or ED visit (HR = 0.80, 95% CI = 0.70-0.95) than individuals in urban areas, independent of symptom burden and comorbidity.

Conclusion

Greater symptom burden was associated with higher risk of hospitalization and ED visits in community-dwelling older adults. Healthcare providers treating older adults should consider symptom burden to be an additional risk factor for subsequent hospital utilization.