Stress & strain in mechanically nonuniform alveoli using clinical input variables: a simple conceptual model.

Clinicians currently monitor pressure and volume at the airway opening, assuming that these observations relate closely to stresses and strains at the micro level. Indeed, this assumption forms the basis of current approaches to lung protective ventilation. Nonetheless, although the airway pressure applied under static conditions may be the same everywhere in healthy lungs, the stresses within a mechanically non-uniform ARDS lung are not. Estimating actual tissue stresses and strains that occur in a mechanically non-uniform environment must account for factors beyond the measurements from the ventilator circuit of airway pressures, tidal volume, and total mechanical power. A first conceptual step for the clinician to better define the VILI hazard requires consideration of lung unit tension, stress focusing, and intracycle power concentration. With reasonable approximations, better understanding of the value and limitations of presently used general guidelines for lung protection may eventually be developed from clinical inputs measured by the caregiver. The primary purpose of the present thought exercise is to extend our published model of a uniform, spherical lung unit to characterize the amplifications of stress (tension) and strain (area change) that occur under static conditions at interface boundaries between a sphere's surface segments having differing compliances. Together with measurable ventilating power, these are incorporated into our perspective of VILI risk. This conceptual exercise brings to light how variables that are seldom considered by the clinician but are both recognizable and measurable might help gauge the hazard for VILI of applied pressure and power.

Cutting Edge: Reduced Adenosine-to-Inosine Editing of Endogenous Alu RNAs in Severe COVID-19 Disease.

Severe COVID-19 disease is associated with elevated inflammatory responses. One form of Aicardi-Goutières syndrome caused by inactivating mutations in ADAR results in reduced adenosine-to-inosine (A-to-I) editing of endogenous dsRNAs, induction of IFNs, IFN-stimulated genes, other inflammatory mediators, morbidity, and mortality. Alu elements, ∼10% of the human genome, are the most common A-to-I-editing sites. Using leukocyte whole-genome RNA-sequencing data, we found reduced A-to-I editing of Alu dsRNAs in patients with severe COVID-19 disease. Dendritic cells infected with COVID-19 also exhibit reduced A-to-I editing of Alu dsRNAs. Unedited Alu dsRNAs, but not edited Alu dsRNAs, are potent inducers of IRF and NF-κB transcriptional responses, IL6, IL8, and IFN-stimulated genes. Thus, decreased A-to-I editing that may lead to accumulation of unedited Alu dsRNAs and increased inflammatory responses is associated with severe COVID-19 disease.

From pressure to tension: a model of damaging inflation stress.

Although the stretch that generates ventilator-induced lung injury (VILI) occurs within the peripheral tissue that encloses the alveolar space, airway pressures and volumes monitor the gas within the interior core of the lung unit, not its cellular enclosure. Measured pressures (plateau pressure, positive end-expiratory pressure, and driving pressure) and tidal volumes paint a highly relevant but incomplete picture of forces that act on the lung tissues themselves. Convenient and clinically useful measures of the airspace, such as pressure and volume, neglect the partitioning of tidal elastic energy into the increments of tension and surface area that constitute actual stress and strain at the alveolar margins. More sharply focused determinants of VILI require estimates of absolute alveolar dimension and morphology and the lung's unstressed volume at rest. We present a highly simplified but informative mathematical model that translates the radial energy of pressure and volume of the airspace into its surface energy components. In doing so it elaborates conceptual relationships that highlight the forces tending to cause end-tidal hyperinflation of aerated units within the 'baby lung' of acute respiratory distress syndrome (ARDS).

Practical assessment of risk of VILI from ventilating power: a conceptual model.

At the bedside, assessing the risk of ventilator-induced lung injury (VILI) requires parameters readily measured by the clinician. For this purpose, driving pressure (DP) and end-inspiratory static 'plateau' pressure ([Formula: see text]) of the tidal cycle are unquestionably useful but lack key information relating to associated volume changes and cumulative strain. 'Mechanical power', a clinical term which incorporates all dissipated ('non-elastic') and conserved ('elastic') energy components of inflation, has drawn considerable interest as a comprehensive 'umbrella' variable that accounts for the influence of ventilating frequency per minute as well as the energy cost per tidal cycle. Yet, like the raw values of DP and [Formula: see text], the absolute levels of energy and power by themselves may not carry sufficiently precise information to guide safe ventilatory practice. In previous work we introduced the concept of 'damaging energy per cycle'. Here we describe how-if only in concept-the bedside clinician might gauge the theoretical hazard of delivered energy using easily observed static circuit pressures ([Formula: see text] and positive end expiratory pressure) and an estimate of the maximally tolerated (threshold) non-dissipated ('elastic') airway pressure that reflects the pressure component applied to the alveolar tissues. Because its core inputs are already in use and familiar in daily practice, the simplified mathematical model we propose here for damaging energy and power may promote deeper comprehension of the key factors in play to improve lung protective ventilation.

Paradoxical Positioning: Does "Head Up" Always Improve Mechanics and Lung Protection?

OBJECTIVES: Head-elevated body positioning, a default clinical practice, predictably increases end-expiratory transpulmonary pressure and aerated lung volume. In acute respiratory distress syndrome (ARDS), however, the net effect of such vertical inclination on tidal mechanics depends upon whether lung recruitment or overdistension predominates. We hypothesized that in moderate to severe ARDS, bed inclination toward vertical unloads the chest wall but adversely affects overall respiratory system compliance (C rs ). DESIGN: Prospective physiologic study. SETTING: Two medical ICUs in the United States. PATIENTS: Seventeen patients with ARDS, predominantly moderate to severe. INTERVENTION: Patients were ventilated passively by volume control. We measured airway pressures at baseline (noninclined) and following bed inclination toward vertical by an additional 15°. At baseline and following inclination, we manually loaded the chest wall to determine if C rs increased or paradoxically declined, suggestive of end-tidal overdistension. MEASUREMENTS AND MAIN RESULTS: Inclination resulted in a higher plateau pressure (supineΔ: 2.8 ± 3.3 cm H 2 O [ p = 0.01]; proneΔ: 3.3 ± 2.5 cm H 2 O [ p = 0.004]), higher driving pressure (supineΔ: 2.9 ± 3.3 cm H 2 O [ p = 0.01]; proneΔ: 3.3 ± 2.8 cm H 2 O [ p = 0.007]), and lower C rs (supine Δ: 3.4 ± 3.7 mL/cm H 2 O [ p = 0.01]; proneΔ: 3.1 ± 3.2 mL/cm H 2 O [ p = 0.02]). Following inclination, manual loading of the chest wall restored C rs and driving pressure to baseline (preinclination) values. CONCLUSIONS: In advanced ARDS, bed inclination toward vertical adversely affects C rs and therefore affects the numerical values for plateau and driving tidal pressures commonly targeted in lung protective strategies. These changes are fully reversed with manual loading of the chest wall, suggestive of end-tidal overdistension in the upright position. Body inclination should be considered a modifiable determinant of transpulmonary pressure and lung protection, directionally similar to tidal volume and positive end-expiratory pressure.

Adenosine-to-Inosine RNA Editing of Alu Double-Stranded (ds)RNAs Is Markedly Decreased in Multiple Sclerosis and Unedited Alu dsRNAs Are Potent Activators of Proinflammatory Transcriptional Responses.

Sensors that detect dsRNA stimulate IFN responses as a defense against viral infection. IFN responses are also well documented in a variety of human autoimmune diseases, including relapsing-remitting multiple sclerosis (MS), in which increased IFN responses result from increased levels of double-stranded endogenous Alu RNAs. Mechanisms underlying increases in double-stranded Alu RNAs in MS are obscure. We find widespread loss of adenosine-to-inosine editing of Alu RNAs in MS. Unedited Alu RNAs are potent activators of both IFN and NF-κB responses via the dsRNA sensors, RIG-I, and TLR3. Minor editing of highly active Alu elements abrogates the ability to activate both transcriptional responses. Thus, adenosine-to-inosine editing may also represent an important defense against autoimmune diseases such as MS.

Paradoxical response to chest wall loading predicts a favorable mechanical response to reduction in tidal volume or PEEP.

BACKGROUND: Chest wall loading has been shown to paradoxically improve respiratory system compliance (CRS) in patients with moderate to severe acute respiratory distress syndrome (ARDS). The most likely, albeit unconfirmed, mechanism is relief of end-tidal overdistension in 'baby lungs' of low-capacity. The purpose of this study was to define how small changes of tidal volume (VT) and positive end-expiratory pressure (PEEP) affect CRS (and its associated airway pressures) in patients with ARDS who demonstrate a paradoxical response to chest wall loading. We hypothesized that small reductions of VT or PEEP would alleviate overdistension and favorably affect CRS and conversely, that small increases of VT or PEEP would worsen CRS. METHODS: Prospective, multi-center physiologic study of seventeen patients with moderate to severe ARDS who demonstrated paradoxical responses to chest wall loading. All patients received mechanical ventilation in volume control mode and were passively ventilated. Airway pressures were measured before and after decreasing/increasing VT by 1 ml/kg predicted body weight and decreasing/increasing PEEP by 2.5 cmH2O. RESULTS: Decreasing either VT or PEEP improved CRS in all patients. Driving pressure (DP) decreased by a mean of 4.9 cmH2O (supine) and by 4.3 cmH2O (prone) after decreasing VT, and by a mean of 2.9 cmH2O (supine) and 2.2 cmH2O (prone) after decreasing PEEP. CRS increased by a mean of 3.1 ml/cmH2O (supine) and by 2.5 ml/cmH2O (prone) after decreasing VT. CRS increased by a mean of 5.2 ml/cmH2O (supine) and 3.6 ml/cmH2O (prone) after decreasing PEEP (P < 0.01 for all). Small increments of either VT or PEEP worsened CRS in the majority of patients. CONCLUSION: Patients with a paradoxical response to chest wall loading demonstrate uniform improvement in both DP and CRS following a reduction in either VT or PEEP, findings in keeping with prior evidence suggesting its presence is a sign of end-tidal overdistension. The presence of 'paradox' should prompt re-evaluation of modifiable determinants of end-tidal overdistension, including VT, PEEP, and body position.

Endogenous double-stranded Alu RNA elements stimulate IFN-responses in relapsing remitting multiple sclerosis.

Various sensors that detect double-stranded RNA, presumably of viral origin, exist in eukaryotic cells and induce IFN-responses. Ongoing IFN-responses have also been documented in a variety of human autoimmune diseases including relapsing-remitting multiple sclerosis (RRMS) but their origins remain obscure. We find increased IFN-responses in leukocytes in relapsing-remitting multiple sclerosis at distinct stages of disease. Moreover, endogenous RNAs isolated from blood cells of these same patients recapitulate this IFN-response if transfected into naïve cells. These endogenous RNAs are double-stranded RNAs, contain Alu and Line elements and are transcribed from leukocyte transcriptional enhancers. Thus, transcribed endogenous retrotransposon elements can co-opt pattern recognition sensors to induce IFN-responses in RRMS.

Profiles of Long Noncoding RNAs in Human Naive and Memory T Cells.

We employed whole-genome RNA-sequencing to profile mRNAs and both annotated and novel long noncoding RNAs (lncRNAs) in human naive, central memory, and effector memory CD4+ T cells. Loci transcribing both lineage-specific annotated and novel lncRNA are adjacent to lineage-specific protein-coding genes in the genome. Lineage-specific novel lncRNA loci are transcribed from lineage-specific typical- and supertranscriptional enhancers and are not multiexonic, thus are more similar to enhancer RNAs. Novel enhancer-associated lncRNAs transcribed from the IFNG locus bind the transcription factor NF-κB and enhance binding of NF-κB to the IFNG genomic locus. Depletion of the annotated lncRNA, IFNG-AS1, or one IFNG enhancer-associated lncRNA abrogates IFNG expression by memory T cells, indicating these lncRNAs have biologic function.

Biogenesis and Transcriptional Regulation of Long Noncoding RNAs in the Human Immune System.

The central dogma of molecular biology states that DNA makes RNA makes protein. Discoveries over the last quarter of a century found that the process of DNA transcription into RNA gives rise to a diverse array of functional RNA species, including genes that code for protein and noncoding RNAs. For decades, the focus has been on understanding how protein-coding genes are regulated to influence protein expression. However, with the completion of the Human Genome Project and follow-up ENCODE data, it is now appreciated that only 2-3% of the genome codes for protein-coding gene exons and that the bulk of the transcribed genome, apart from ribosomal RNAs, is at the level of noncoding RNA genes. In this article, we focus on the biogenesis and regulation of a distinct class of noncoding RNA molecules termed long, noncoding RNAs in the context of the immune system.

Techniques of autologous pericardial leaflet replacement for bicuspid aortic valve endocarditis.

BACKGROUND AND AIM OF THE STUDY: Valvular endocarditis constitutes high-risk cardiac surgery, with worse early and late results than for other disorders. Current data suggest that repairing endocarditis valves may produce better outcomes, but bicuspid endocarditis has been difficult to repair. Given the excellent early and late results now being achieved with autologous pericardial leaflet replacement, the present study involved complete pericardial leaflet replacement, a procedure that could facilitate the autologous reconstruction of bicuspid valves. METHODS: Four patients with endocarditis of bicuspid valves, each exhibiting variations in anatomy and presentation, were included. All four patients had received antibiotics preoperatively and had been converted to culture-negative. All had infection of the fused leaflet, and three had retention of their normal non-fused leaflets for the repair. Using glutaraldehyde-fixed autologous pericardium, all damaged leaflets were fully replaced, employing bileaflet repairs in three patients and a trileaflet repair in one patient. One patient required both bicuspid leaflets to be replaced with two autologous pericardial leaflets because of concurrent calcification. RESULTS: All four patients recovered uneventfully, and had fully competent valves with minimal gradients. All were subsequently managed without anticoagulation, and during up to two years of follow up the reconstructed valves functioned normally. None of the patients experienced any valve-related complications. CONCLUSION: In an anatomic spectrum of bicuspid endocarditis, the preservation of normal leaflets and complete replacement of damaged leaflets with autologous pericardium has provided an excellent reparative solution. This method could allow a stable autologous reconstruction in the majority of patients, although more experience and follow up will be necessary to fully validate the procedure.

Medical practices display power law behaviors similar to spoken languages.

BACKGROUND: Medical care commonly involves the apprehension of complex patterns of patient derangements to which the practitioner responds with patterns of interventions, as opposed to single therapeutic maneuvers. This complexity renders the objective assessment of practice patterns using conventional statistical approaches difficult. METHODS: Combinatorial approaches drawn from symbolic dynamics are used to encode the observed patterns of patient derangement and associated practitioner response patterns as sequences of symbols. Concatenating each patient derangement symbol with the contemporaneous practitioner response symbol creates "words" encoding the simultaneous patient derangement and provider response patterns and yields an observed vocabulary with quantifiable statistical characteristics. RESULTS: A fundamental observation in many natural languages is the existence of a power law relationship between the rank order of word usage and the absolute frequency with which particular words are uttered. We show that population level patterns of patient derangement: practitioner intervention word usage in two entirely unrelated domains of medical care display power law relationships similar to those of natural languages, and that-in one of these domains-power law behavior at the population level reflects power law behavior at the level of individual practitioners. CONCLUSIONS: Our results suggest that patterns of medical care can be approached using quantitative linguistic techniques, a finding that has implications for the assessment of expertise, machine learning identification of optimal practices, and construction of bedside decision support tools.

Nanoparticle Delivery of Immunostimulatory Alu RNA for Cancer Immunotherapy.

It was recently found that patients with relapsing remitting multiple sclerosis exhibit widespread loss of adenosine-to-inosine (A-to-I) RNA editing, which contributes to the accumulation of immunostimulatory double-stranded Alu RNA in circulating leukocytes and an attendant increase in levels of proinflammatory cytokines (e.g., type I IFNs). A specific Alu RNA (i.e., AluJb RNA) was implicated in activating multiple RNA-sensing pathways and found to be a potent innate immune agonist. Here, we have performed a bioinformatic analysis of A-to-I RNA editing in human melanoma samples and determined that pre-therapy levels of A-to-I RNA editing negatively correlate with survival times, suggesting that an accumulation of endogenous double-stranded Alu RNA might contribute to cancer patient survival. Furthermore, we demonstrated that immunostimulatory Alu RNA can be leveraged pharmacologically for cancer immunotherapy. AluJb RNA was in vitro transcribed and then formulated with endosome-destabilizing polymer nanoparticles to improve intracellular delivery of the RNA and enable activation of RNA-sensing pathways. AluJb RNA/polymer complexes (i.e., Alu-NPs) were engineered to form colloidally stable nanoparticles that exhibited immunostimulatory activity in vitro and in vivo. Finally, the therapeutic potential of Alu-NPs for the treatment of cancer was demonstrated by attenuated tumor growth and prolonged survival in the B16.F10 murine melanoma tumor model. Thus, these data collectively implicate intratumoral Alu RNA as a potentiator of antitumor innate immunity and identify AluJb RNA as a novel nucleic acid immunotherapeutic for cancer. Significance: Loss of A-to-I editing leads to accumulation of unedited Alu RNAs that activate innate immunity via RNA-sensing pattern recognition receptors. When packaged into endosome-releasing polymer nanoparticles, AluJB RNA becomes highly immunostimulatory and can be used pharmacologically to inhibit tumor growth in mouse melanoma models. These findings identify Alu RNAs as a new class of nucleic acid innate immune agonists for cancer immunotherapy.

Increased sensitivity to apoptosis induced by methotrexate is mediated by JNK.

OBJECTIVE: Low-dose methotrexate (MTX) is an effective therapy for rheumatoid arthritis (RA), yet its mechanism of action is incompletely understood. The aim of this study was to explore the induction of apoptosis by MTX. METHODS: Flow cytometry was performed to assess changes in the levels of intracellular proteins, reactive oxygen species (ROS), and apoptosis. Quantitative polymerase chain reaction was performed to assess changes in the transcript levels of select target genes in response to MTX. RESULTS: MTX did not directly induce apoptosis but rather "primed" cells for markedly increased sensitivity to apoptosis via either mitochondrial or death receptor pathways, by a JNK-dependent mechanism. Increased sensitivity to apoptosis was mediated, at least in part, by MTX-dependent production of ROS, JNK activation, and JNK-dependent induction of genes whose protein products promote apoptosis. Supplementation with tetrahydrobiopterin blocked these MTX-induced effects. Patients with RA who were receiving low-dose MTX therapy expressed elevated levels of the JNK target gene, jun. CONCLUSION: Our results support a model whereby MTX inhibits reduction of dihydrobiopterin to tetrahydrobiopterin, resulting in increased production of ROS, increased JNK activity, and increased sensitivity to apoptosis. The finding of increased jun levels in patients with RA receiving low-dose MTX supports the notion that this pathway is activated by MTX in vivo and may contribute to the efficacy of MTX in inflammatory disease.

Intracycle power distribution in a heterogeneous multi-compartmental mathematical model: possible links to strain and VILI.

BACKGROUND: Repeated expenditure of energy and its generation of damaging strain are required to injure the lung by ventilation (VILI). Mathematical modeling of passively inflated, single-compartment lungs with uniform parameters for resistance and compliance indicates that standard clinical modes (flow patterns) differ impressively with respect to the timing and intensity of energy delivery-the intracycle power (ICP) that determines parenchymal stress and strain. Although measures of elastic ICP may accurately characterize instantaneous rates of global energy delivery, how the ICP component delivered to a compartment affects the VILI-linked variable of strain is determined by compartmental mechanics, compartmental size and mode of gas delivery. We extended our one-compartment model of ICP to a multi-compartment setting that varied those characteristics. MAIN FINDINGS: The primary findings of this model/simulation indicate that: (1) the strain and strain rate experienced within a modeled compartment are nonlinear functions of delivered energy and power, respectively; (2) for a given combination of flow profile and tidal volume, resting compartmental volumes influence their resulting maximal strains in response to breath delivery; (3) flow profile is a key determinant of the maximal strain as well as maximal strain rate experienced within a multi-compartment lung. By implication, different clinician-selected flow profiles not only influence the timing of power delivery, but also spatially distribute the attendant strains of expansion among compartments with diverse mechanical properties. Importantly, the contours and magnitudes of the compartmental ICP, strain, and strain rate curves are not congruent; strain and strain rate do not necessarily follow the compartmental ICP, and the hierarchy of amplitudes among compartments for these variables may not coincide. CONCLUSIONS: Different flow patterns impact how strain and strain rate develop as compartmental volume crests to its final value. Notably, as inflation proceeds, strain rate may rise or fall even as total strain, a monotonic function of volume, steadily (and predictably) rises. Which flow pattern serves best to minimize the maximal strain rate and VILI risk experienced within any sector, therefore, may strongly depend on the nature and heterogeneity of the mechanical properties of the injured lung.

Alu RNA Structural Features Modulate Immune Cell Activation and A-to-I Editing of Alu RNAs Is Diminished in Human Inflammatory Bowel Disease.

Alu retrotransposons belong to the class of short interspersed nuclear elements (SINEs). Alu RNA is abundant in cells and its repetitive structure forms double-stranded RNAs (dsRNA) that activate dsRNA sensors and trigger innate immune responses with significant pathological consequences. Mechanisms to prevent innate immune activation include deamination of adenosines to inosines in dsRNAs, referred to as A-to-I editing, degradation of Alu RNAs by endoribonucleases, and sequestration of Alu RNAs by RNA binding proteins. We have previously demonstrated that widespread loss of Alu RNA A-to-I editing is associated with diverse human diseases including viral (COVID-19, influenza) and autoimmune diseases (multiple sclerosis). Here we demonstrate loss of A-to-I editing in leukocytes is also associated with inflammatory bowel diseases. Our structure-function analysis demonstrates that ability to activate innate immune responses resides in the left arm of Alu RNA, requires a 5'-PPP, RIG-I is the major Alu dsRNA sensor, and A-to-I editing disrupts both structure and function. Further, edited Alu RNAs inhibit activity of unedited Alu RNAs. Altering Alu RNA nucleotide sequence increases biological activity. Two classes of Alu RNAs exist, one class stimulates both IRF and NF-kB transcriptional activity and a second class only stimulates IRF transcriptional activity. Thus, Alu RNAs play important roles in human disease but may also have therapeutic potential.

Reduced RNA adenosine-to-inosine editing in hippocampus vasculature associated with Alzheimer's disease.

Alzheimer's disease is the most common form of dementia and recent studies identify a type 1 interferon response in Alzheimer's disease possibly driving neuro-inflammation and other Alzheimer's disease pathologies. Loss of adenosine-to-inosine editing of endogenous Alu RNAs results in accumulation of Alu double-stranded RNAs, activation of double-stranded RNA sensors, and induction of interferon and nuclear factor kappa B regulated genes. Here, we investigated if changes in adenosine-to-inosine editing were associated with presence of Alzheimer's disease in total prefrontal cortex, total hippocampus, cortex vasculature and hippocampus vasculature using available RNA sequencing files. We found similar levels of Alu RNA adenosine-to-inosine editing in cortex and cortex vasculature from individuals with Alzheimer's disease or normal cognition at the time of death and brain donation. We found modest and substantial loss of adenosine-to-inosine editing in hippocampus and hippocampus vasculature, respectively, in Alzheimer's disease relative to normal cognition and increased expression of interferon and nuclear factor kappa B regulated genes in hippocampus. Unedited Alu RNAs as found in Alzheimer's disease hippocampus vasculature were potent innate immune activators while edited Alu RNAs as found in normal cognition hippocampus vasculature were weak innate immune activators. Taken together, our results support a model whereby loss of Alu RNA adenosine-to-inosine editing in hippocampus results in innate immune activation that may contribute to Alzheimer's disease pathogenesis.

Increased Development of Th1, Th17, and Th1.17 Cells Under T1 Polarizing Conditions in Juvenile Idiopathic Arthritis.

In juvenile idiopathic arthritis (JIA) inflammatory T cells and their produced cytokines are drug targets and play a role in disease pathogenesis. Despite their clinical importance, the sources and types of inflammatory T cells involved remain unclear. T cells respond to polarizing factors to initiate types of immunity to fight infections, which include immunity types 1 (T1), 2 (T2), and 3 (T17). Polarizing factors drive CD4+ T cells towards T helper (Th) cell subtypes and CD8+ T cells towards cytotoxic T cell (Tc) subtypes. T1 and T17 polarization are associated with autoimmunity and production of the cytokines IFNγ and IL-17 respectively. We show that JIA and child healthy control (HC) peripheral blood mononuclear cells are remarkably similar, with the same frequencies of CD4+ and CD8+ naïve and memory T cell subsets, T cell proliferation, and CD4+ and CD8+ T cell subsets upon T1, T2, and T17 polarization. Yet, under T1 polarizing conditions JIA cells produced increased IFNγ and inappropriately produced IL-17. Under T17 polarizing conditions JIA T cells produced increased IL-17. Gene expression of IFNγ, IL-17, Tbet, and RORγT by quantitative PCR and RNA sequencing revealed activation of immune responses and inappropriate activation of IL-17 signaling pathways in JIA polarized T1 cells. The polarized JIA T1 cells were comprised of Th and Tc cells, with Th cells producing IFNγ (Th1), IL-17 (Th17), and both IFNγ-IL-17 (Th1.17) and Tc cells producing IFNγ (Tc1). The JIA polarized CD4+ T1 cells expressed both Tbet and RORγT, with higher expression of the transcription factors associated with higher frequency of IL-17 producing cells. T1 polarized naïve CD4+ cells from JIA also produced more IFNγ and more IL-17 than HC. We show that in JIA T1 polarization inappropriately generates Th1, Th17, and Th1.17 cells. Our data provides a tool for studying the development of heterogeneous inflammatory T cells in JIA under T1 polarizing conditions and for identifying pathogenic immune cells that are important as drug targets and diagnostic markers.

Reduced A-to-I editing of endogenous Alu RNAs in lung after SARS-CoV-2 infection.

Due to potential severity of disease caused by SARS-CoV-2 infection, it is critical to understand both mechanisms of viral pathogenesis as well as diversity of host responses to infection. Reduced A-to-I editing of endogenous double-stranded RNAs (dsRNAs), as a result of inactivating mutations in ADAR, produces one form of Aicardi-Goutières Syndrome, with an immune response similar to an anti-viral response. By analyzing whole genome RNA sequencing data, we find reduced levels of A-to-I editing of endogenous Alu RNAs in normal human lung cells after infection by SARS-CoV-2 as well as in lung biopsies from patients with SARS-CoV-2 infections. Unedited Alu RNAs, as seen after infection, induce IRF and NF-kB transcriptional responses and downstream target genes, while edited Alu RNAs as seen in the absence of infection, fail to activate these transcriptional responses. Thus, decreased A-to-I editing may represent an important host response to SARS-CoV-2 infection.

Intracycle power and ventilation mode as potential contributors to ventilator-induced lung injury.

BACKGROUND: High rates of inflation energy delivery coupled with transpulmonary tidal pressures of sufficient magnitude may augment the risk of damage to vulnerable, stress-focused units within a mechanically heterogeneous lung. Apart from flow amplitude, the clinician-selected flow waveform, a relatively neglected dimension of inflation power, may distribute inflation energy of each inflation cycle non-uniformly among alveoli with different mechanical properties over the domains of time and space. In this initial step in modeling intracycle power distribution, our primary objective was to develop a mathematical model of global intracycle inflation power that uses clinician-measurable inputs to allow comparisons of instantaneous ICP profiles among the flow modes commonly encountered in clinical practice: constant, linearly decelerating, exponentially decelerating (pressure control), and spontaneous (sinusoidal). METHODS: We first tested the predictions of our mathematical model of passive inflation with the actual physical performance of a mechanical ventilator-lung system that simulated ventilation to three types of patients: normal, severe ARDS, and severe airflow obstruction. After verification, model predictions were then generated for 5000 'virtual ARDS patients'. Holding constant the tidal volume and inflation time between modes, the validated model then varied the flow profile and quantitated the resulting intensity and timing of potentially damaging 'elastic' energy and intracycle power (pressure-flow product) developed in response to random combinations of machine settings and severity levels for ARDS. RESULTS: Our modeling indicates that while the varied flow patterns ultimately deliver similar total amounts of alveolar energy during each breath, they differ profoundly regarding the potentially damaging pattern with which that energy distributes over time during inflation. Pressure control imposed relatively high maximal intracycle power. CONCLUSIONS: Flow amplitude and waveform may be relatively neglected and modifiable determinants of VILI risk when ventilating ARDS.