Key points
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The transcription factor Dbx1 gives rise to putatively respiratory rhythm‐generating neurons in the pre‐Bötzinger complex. Comparative analysis of Dbx1‐derived (Dbx1+) and non‐Dbx1‐ ...derived (Dbx1−) neurons can help elucidate the cellular bases of respiratory rhythm generation.
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In vitro, Dbx1+ neurons activate earlier in the respiratory cycle, discharge larger magnitude inspiratory bursts and exhibit a lower rheobase compared with Dbx1− neurons.
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The Dbx1+ neurons tend to express the intrinsic currents IA (transient outward A‐current) and Ih (hyperpolarization‐activated current) in diametric opposition, which may facilitate temporal summation of excitatory synaptic inputs, whereas the Dbx1− neurons show no significant pattern of expression regarding IA and Ih.
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The Dbx1+ neurons exhibit smooth, spineless dendrites that project in the transverse plane, whereas the Dbx1− neurons are confined to the transverse plane to a lesser extent and sometimes exhibit spines.
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The properties of Dbx1+ neurons that may contribute to respiratory rhythmogenesis include a high level of excitability linked to ongoing network activity and dendritic properties that may facilitate synaptic integration.
Breathing in mammals depends on an inspiratory‐related rhythm that is generated by glutamatergic neurons in the pre‐Bötzinger complex (preBötC) of the lower brainstem. A substantial subset of putative rhythm‐generating preBötC neurons derive from a single genetic line that expresses the transcription factor Dbx1, but the cellular mechanisms of rhythmogenesis remain incompletely understood. To elucidate these mechanisms, we carried out a comparative analysis of Dbx1‐expressing neurons (Dbx1+) and non‐Dbx1‐derived (Dbx1−) neurons in the preBötC. Whole‐cell recordings in rhythmically active newborn mouse slice preparations showed that Dbx1+ neurons activate earlier in the respiratory cycle and discharge greater magnitude inspiratory bursts compared with Dbx1− neurons. Furthermore, Dbx1+ neurons required less input current to discharge spikes (rheobase) in the context of network activity. The expression of intrinsic membrane properties indicative of A‐current (IA) and hyperpolarization‐activated current (Ih) tended to be mutually exclusive in Dbx1+ neurons. In contrast, there was no such relationship in the expression of currents IA and Ih in Dbx1− neurons. Confocal imaging and digital morphological reconstruction of recorded neurons revealed dendritic spines on Dbx1− neurons, but Dbx1+ neurons were spineless. The morphology of Dbx1+ neurons was largely confined to the transverse plane, whereas Dbx1− neurons projected dendrites to a greater extent in the parasagittal plane. The putative rhythmogenic nature of Dbx1+ neurons may be attributable, in part, to a higher level of intrinsic excitability in the context of network synaptic activity. Furthermore, Dbx1+ neuronal morphology may facilitate temporal summation and integration of local synaptic inputs from other Dbx1+ neurons, taking place largely in the dendrites, which could be important for initiating and maintaining bursts and synchronizing activity during the inspiratory phase.
HIV-infected patients are at higher risk of developing oral mucosal infection and Epstein–Barr virus (EBV)-associated B cell malignancies. However, the potential role of oral immunity in the ...pathogenesis of oral lesions is unknown. Tonsils are oral-pharyngeal mucosal-associated lymphoid tissues that play an important role in oral mucosal immunity. In this study, we investigated the changes of innate and adaptive immune cells in macaque tonsils during chronic SIV infection. We found significantly higher frequencies of classical monocytes, CD3+CD56+ (NKT-like) cells, CD3
+
CD4
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CD8
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(DP), and CD161
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CD4 T cells in tonsils from chronic infected compared to naïve animals. On the contrary, intermediate monocytes and CD3
+
CD4
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CD8
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(DN) cells were lower in chronic SIV-infected macaques. We further confirmed a recently described small B-cell subset, NKB cells, were higher during chronic infection. Furthermore, both adaptive and innate cells showed significantly higher TNF-α and cytotoxic marker CD107a, while IL-22 production was significantly reduced in innate and adaptive immune cells in chronic SIV-infected animals. A dramatic reduction of IFN-γ production by innate immune cells might indicate enhanced susceptibility to EBV infection and potential transformation of B cells in the tonsils. In summary, our observation shows that the SIV-associated immune responses are distinct in the tonsils compared to other mucosal tissues. Our data extends our understanding of the oral innate immune system during SIV infection and could aid future studies in evaluating the role of tonsillar immune cells during HIV-associated oral mucosal infections.
This article moves beyond analysis methods related to a traditional relational database or network analysis and offers a novel graph network technique to yield insights from a hospital’s emergency ...department work model. The modeled data were saved in a Neo4j graphing database as a time-varying graph (TVG), and related metrics, including degree centrality and shortest paths, were calculated and used to obtain time-related insights from the overall system. This study demonstrated the value of using a TVG method to model patient flows during emergency department stays. It illustrated dynamic relationships among hospital and consulting units that could not be shown with traditional analyses. The TVG approach augments traditional network analysis with temporal-related outcomes including time-related patient flows, temporal congestion points details, and periodic resource constraints. The TVG approach is crucial in health analytics to understand both general factors and unique influences that define relationships between time-influenced events. The resulting insights are useful to administrators for making decisions related to resource allocation and offer promise for understanding impacts of physicians and nurses engaged in specific patient emergency department experiences. We also analyzed customer ratings and reviews to better understand overall patient satisfaction during their journey through the emergency department.
BACKGROUND: Evidence suggests that COVID-19 predisposes to cardiovascular diseases (CVDs). While monocytes/macrophages play a central role in the immunopathogenesis of atherosclerosis, less is known ...about their immunopathogenic mechanisms that lead to CVDs during COVID-19. Natural killer (NK) cells, which play an intermediary role during pathologies like atherosclerosis, are dysregulated during COVID-19. Here, we sought to investigate altered immune cells and their associations with CVD risk during severe COVID-19. METHODS: We measured plasma biomarkers of CVDs and determined phenotypes of circulating immune subsets using spectral flow cytometry. We compared these between patients with severe COVID-19 (severe, n=31), those who recovered from severe COVID-19 (recovered, n=29), and SARS-CoV-2–uninfected controls (controls, n=17). In vivo observations were supported using in vitro assays to highlight possible mechanistic links between dysregulated immune subsets and biomarkers during and after COVID-19. We performed multidimensional analyses of published single-cell transcriptome data of monocytes and NK cells during severe COVID-19 to substantiate in vivo findings. RESULTS: During severe COVID-19, we observed alterations in cardiometabolic biomarkers including oxidized–low-density lipoprotein, which showed decreased levels in severe and recovered groups. Severe patients exhibited dysregulated monocyte subsets, including increased frequencies of proinflammatory intermediate monocytes (also observed in the recovered) and decreased nonclassical monocytes. All identified NK-cell subsets in the severe COVID-19 group displayed increased expression of activation and tissue-resident markers, such as CD69. We observed significant correlations between altered immune subsets and plasma oxidized–low-density lipoprotein levels. In vitro assays revealed increased uptake of oxidized–low-density lipoprotein into monocyte-derived macrophages in the presence of NK cells activated by plasma of patients with severe COVID-19. Transcriptome analyses confirmed enriched proinflammatory responses and lipid dysregulation associated with epigenetic modifications in monocytes and NK cells during severe COVID-19. CONCLUSIONS: Our study provides new insights into the involvement of monocytes and NK cells in the increased CVD risk observed during and after COVID-19.
Abstract
COVID-19, the disease caused by SARS-CoV-2, has led to a global public health emergency. Severity of disease course may be related to a dysregulated immune response and pre-existing health ...conditions. Recent studies have demonstrated that SARS-CoV-2 infection may directly or indirectly lead to an increase in cardiometabolic complications in patients with pre-existing type-2 diabetes mellites (T2DM) when compare to non-DM patients. A lack of mechanistic and systematic studies on how SARS-CoV-2 infection related immune responses may contribute to increase risk of cardiometabolic complications in pre-existing T2DM patients, hinder early risk identification and therapeutic interventions. Thus, in this study we investigate the biomarkers of cardiometabolic risk in non-DM and T2DM, severe COVID-19 patients admitted to the Intensive care unit.
Using high-dimensional flowcytometry and immune biomarker assays, we investigated functional and phenotypic changes in immune subsets in whole blood and plasma biomarkers of cardiovascular disease in healthy donors (n=17), T2DM severe-COVID-19 patients (n=10), non-diabetic severe-COVID-19 patients (n=10) admitted to the OSU medical center's intensive care unit.
We found neutrophils and Intermediate monocytes (ITM) were significantly higher in the T2DM group compared to non T2DM patients. However, activated (HLA-DR+) NKT-like cells and NKG2A+ CD56 Dim CD16+ NK cells, were significantly lower in the T2DM-COVID-19+ group. Interestingly, LBP, FABP4, sCD14, IL-1b, RANTES and MIP-1a were significantly higher in the COVID-19 T2DM patients.
In this study, we identify core immune signatures that may predict increased cardiovascular disease risk in T2DM patients who had severe COVID-19.
Supported by PI's startup funding
Abstract
Severe Acute Respiratory Syndrome Coronavirus 2 (SARS□CoV□ 2) is a highly pathogenic corona virus which causes COVID-19 and resulted in millions of deaths and led to a global public health ...emergency. An effective and appropriate immune response is essential to control and eliminate viral infections, however, dysregulated immune responses may lead to immunopathology in viral infections. Clinical data showed that COVID-19 may promote the development of cardiovascular disorders (CVDs). However, exact mechanism associated with CVDs in COVID-19 patients is currently unknown. Monocytes are one of the major immune cell subsets that contribute to host defense against many infections but also associated with immunopathology and development of CVDs. Thus, in this study we investigated the role of monocyte subsets in COVID-19 associated CVDs. By using high dimensional flowcytometry, immune biomarker assays and multi variant data analysis in healthy donors (n=17), severe-COVID-19 patients (n=20) (ICU) and COVID-19 recovered individuals (n=30), we found elevated intermediate monocytes and Monocyte chemoattractant protein-1, one of the most important chemokines that regulates migration and infiltration of monocytes to the subendothelial space, where they may become foam cells. Spearman correlation network analysis showed that strong correlation between increase intermediate monocytes in the whole blood and plasma cardimetabolic biomarkers such as fatty acid binding protein 4, C-reactive protein, soluble CD14 and LPS binding protein in ICU patients. Our data show for the first time that the possible role of monocytes in the development of CVDs in ICU patients.
Abstract
Covid-19, the disease caused by SARS-CoV-2 infection, has resulted in millions of deaths and led to a global public health emergency. SARS-CoV-2 infected patients exhibit a wide variety of ...phasic clinical manifestations ranging from asymptomatic to severe complications and death. SARS-CoV-2 infection can lead to excessive immune activation, inflammation and multi-organ damage. Clinical data showed that COVID-19 may promote the development of cardiovascular disorders (CVDs). Immune activation, thrombosis, cytokine storm, and altered adhesion molecule expression on leukocyte populations have been proposed as possible mechanisms that trigger COVID-19 associated CVDs. A lack of systematic studies on how SARS-CoV-2 infection triggered immune responses that may lead to CVDs, hinder early risk identification and therapeutic interventions. In this study, by using deep immune profiling and extensive cytokine and chemokine profiling, we explore potential mechanisms of developing CVDs in severe COVID-19 patients (ICU) (n=20) as well as patients recovered from COVID-19 (RD) (n=30). We identify core immune signatures in ICU patients and RD compared to healthy controls (n=17) that may predict potential cardiovascular risk. We found that significantly elevated eosinophils and neutrophils and increased circulating levels of tissue factor, fatty acid binding protein 4 and, LPS binding protein in ICU patients suggested increased immune activation and thrombotic risk. Interestingly, we found significant elevation of several immune parameters (TIMP-1, TIMP-2, Monocytes) that were associated with cardiometabolic risk, in RD group. Thus, our data suggest a possible mechanistic link between severe COVID-19 and cardiometabolic risk.
The relationship between neuron morphology and function is a perennial issue in neuroscience. Information about synaptic integration, network connectivity, and the specific roles of neuronal ...subpopulations can be obtained through morphological analysis of key neurons within a microcircuit. Here we present morphologies of two classes of brainstem respiratory neurons. First, interneurons derived from Dbx1-expressing precursors (Dbx1 neurons) in the preBötzinger complex (preBötC) of the ventral medulla that generate the rhythm for inspiratory breathing movements. Second, Dbx1 neurons of the intermediate reticular formation that influence the motor pattern of pharyngeal and lingual movements during the inspiratory phase of the breathing cycle. We describe the image acquisition and subsequent digitization of morphologies of respiratory Dbx1 neurons from the preBötC and the intermediate reticular formation that were first recorded in vitro. These data can be analyzed comparatively to examine how morphology influences the roles of Dbx1 preBötC and Dbx1 reticular interneurons in respiration and can also be utilized to create morphologically accurate compartmental models for simulation and modeling of respiratory circuits.
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