Neuromodulatory effects on synchrony and network reorganization in networks of coupled Kuramoto oscillators.

Neuromodulatory processes in the brain can critically change signal processing on a cellular level leading to dramatic changes in network level reorganization. Here, we use coupled non-identical Kuramoto oscillators to investigate how changes in the shape of phase response curves from Type 1 to Type 2, mediated by varying ACh levels, coupled with activity dependent plasticity may alter network reorganization. We first show that when plasticity is absent, the Type 1 networks, as expected, exhibit asynchronous dynamics with oscillators of the highest natural frequency robustly evolving faster in terms of their phase dynamics. At the same time, the Type 2 networks synchronize, with oscillators locked so that the ones with higher natural frequency have a constant phase lead as compared to the ones with lower natural frequency. This relationship establishes a robust mapping between the frequency and oscillators' phases in the network, leading to structure/frequency mapping when plasticity is present. Further we show that while connection plasticity can produce stable synchrony (so called splay states) in Type 1 networks, the structure/frequency reorganization observed in Type 2 networks is not present.

Role of succinate in airway epithelial cell regulation following traumatic lung injury.

Lung contusion and gastric aspiration (LC and GA) are major risk factors for developing acute respiratory distress following trauma. Hypoxia from lung injury is mainly regulated by hypoxia-inducible factor 1α (HIF-1α). Published data from our group indicate that HIF-1α regulation in airway epithelial cells (AEC) drives the acute inflammatory response following LC and GA. Metabolomic profiling and metabolic flux of Type II AEC following LC revealed marked increases in glycolytic and TCA intermediates in vivo and in vitro that were HIF-1α dependent. GLUT-1/4 expression was also increased in HIF-1α+/+ mice, suggesting that increased glucose entry may contribute to increased intermediates. Importantly, lactate incubation in vitro on Type II cells did not significantly increase the inflammatory byproduct IL-1ß. Contrastingly, succinate had a direct proinflammatory effect on human small AEC by IL-1ß generation in vitro. This effect was reversed by dimethylmalonate, suggesting an important role for succinate dehydrogenase in mediating HIF-1α effects. We confirmed the presence of the only known receptor for succinate binding, SUCNR1, on Type II AEC. These results support the hypothesis that succinate drives HIF-1α-mediated airway inflammation following LC. This is the first report to our knowledge of direct proinflammatory activation of succinate in nonimmune cells such as Type II AEC in direct lung injury models.

Hypoxia-Inducible Factor 1α and Its Role in Lung Injury: Adaptive or Maladaptive.

Hypoxia-inducible factors (HIFs) are transcription factors critical for the adaptive response to hypoxia. There is also an essential link between hypoxia and inflammation, and HIFs have been implicated in the dysregulated immune response to various insults. Despite the prevalence of hypoxia in tissue trauma, especially involving the lungs, there remains a dearth of studies investigating the role of HIFs in clinically relevant injury models. Here, we summarize the effects of HIF-1α on the vasculature, metabolism, inflammation, and apoptosis in the lungs and review the role of HIFs in direct lung injuries, including lung contusion, acid aspiration, pneumonia, and COVID-19. We present data that implicates HIF-1α in the context of arguments both in favor and against its role as adaptive or injurious in the propagation of the acute inflammatory response in lung injuries. Finally, we discuss the potential for pharmacological modulation of HIFs as a new class of therapeutics in the modern intensive care unit.

Therapeutic potential of curcumin in ARDS and COVID-19.

Curcumin is a safe, non-toxic, readily available and naturally occurring compound, an active constituent of Curcuma longa (turmeric). Curcumin could potentially treat diseases, but faces poor physicochemical and pharmacological characteristics. To overcome these limitations, we developed a stable, water-soluble formulation of curcumin called cyclodextrin-complexed curcumin (CDC). We have previously shown that direct delivery of CDC to the lung following lipopolysaccharides exposure reduces acute lung injury (ALI) and effectively reduces lung injury, inflammation and mortality in mice following Klebsiella pneumoniae. Recently, we found that administration of CDC led to a significant reduction in angiotensin-converting enzyme 2 and signal transducer and activator of transcription 3 expression in gene and protein levels following pneumonia, indicating its potential in treating coronavirus disease 2019 (COVID-19). In this review, we consider the clinical features of ALI and acute respiratory distress syndrome (ARDS) and the role of curcumin in modulating the pathogenesis of bacterial/viral-induced ARDS and COVID-19.

The COVID-19 Pandemic Impact on Pediatric Endoscopies in a Single Center.

Pediatric endoscopic procedures are considered at high risk for coronavirus disease 2019 (COVID-19) transmission, as it can be aerosolized during the upper and lower endoscopy. The data on the pediatric endoscopy experience during the COVID-19 pandemic is scarce. Our research goal is to explore the influence of the pandemic on our endoscopy practice. We retrospectively reviewed the charts of pediatric patients ages 1 to 21 years during the first year of the pandemic and compared it to the previous year. We found that procedural volumes were only impacted in the first 2 months of the pandemic and then returned to normal monthly procedural volumes. We also surveyed personal protective equipment (PPE) requirements and pre-procedural screening protocols. One percent of all pediatric endoscopy patients tested positive for COVID-19 during the pandemic year. We demonstrate that the combination of pre-procedural testing and infection control precautions enabled pediatric endoscopies to be performed safely in children.

Hypoxia-inducible factor (HIF)-1α-induced regulation of lung injury in pulmonary aspiration is mediated through NF-kB.

Aspiration-induced lung injury is a common grievance encountered in the intensive care unit (ICU). It is a significant risk factor for improving ventilator-associated pneumonia (VAP) and acute respiratory distress syndrome (ARDS). Hypoxia-inducible factor (HIF)-1α is one of the primary transcription factors responsible for regulating the cellular response to changes in oxygen tension. Here, we sought to determine the role of HIF-1α and specifically the role of type 2 alveolar epithelial cells in generating the acute inflammatory response following acid and particles (CASP) aspiration. Previous studies show HIF-1 α is involved in regulating the hypoxia-stimulated expression of MCP-1 in mice and humans. The CASP was induced in C57BL/6, ODD-Luc, HIF-1α (+/+) control, and HIF-1α conditional knockout (HIF-1α (-/-) mice). Following an injury in ODD mice, explanted organs were subjected to IVIS imaging to measure the degree of hypoxia. HIF-1α expression, BAL albumin, cytokines, and histology were measured following CASP. In C57BL/6 mice, the level of HIF-1α was increased at 1 h after CASP. There were significantly increased levels of albumin and cytokines in C57BL/6 and ODD-Luc mice lungs following CASP. HIF-1α (+/+) mice given CASP demonstrated a synergistic increase in albumin leakage, increased pro-inflammatory cytokines, and worse injury. MCP-1 antibody neutralized HIF-1α (+/+) mice showed reduced granuloma formation. The NF-κB expression was increased substantially in the HIF-1α (+/+) mice following CASP compared to HIF-1α (-/-) mice. Our data collectively identify that HIF-1α upregulation of the acute inflammatory response depends on NF-κB following CASP.