Impaired tryptophan metabolism by type 2 inflammation in epithelium worsening asthma

Previous researches indicate that tryptophan metabolism is critical to allergic inflammation and that indoleamine 2,3-dioxygenase 1 (IDO1), as a key enzyme, is known for its immunosuppressive properties. Therefore, we are aimed to explore whether tryptophan metabolism, especially IDO1, influences allergic asthma and clarify specific mechanism. With the analysis of clinical data, exploration in cell experiments, and verifying in HDM-induced asthma mice models, we finally found that in allergic asthma, low level of T1 cytokines along with high level of T2 cytokines inhibited the expression of IDO1 in airway epithelium, hampering the kynurenine pathway in tryptophan metabolism and decreasing the level of intracellular kynurenine (Kyn). As an endogenous ligand of aryl hydrocarbon receptor, Kyn regulated the expression of cystathionine-γ-lyase (CTH). Notably, in asthma models, enhancing either IDO1 or H2S relieved asthma, while inhibiting the activity of CTH exacerbated it. IDO1-Kyn-CTH pathway could be a potential target for treatment for allergic asthma.

NMDA Receptor Modulation in COVID-19-Associated Acute Respiratory Syndrome in both In Silico and In Vitro Approach

The normal function of the N-methyl D-aspartate receptors (NMDAR) in human lungs depends on precisely regulated synaptic glutamate levels. Pathophysiology of the lungs is brought on by the changes in homeostasis of glutamate in the synapsis that leads to abnormal NMDAR activity. Severe acute respiratory syndrome (SARS) primarily results in lung infections, particularly lung muscle stiffening, and NMDA receptor potentiation may increase calcium ion influx and support downstream signaling mechanisms. Hence, NMDAR modulators that depend on glutamate levels could be therapeutically useful medications with fewer unintended side effects. A compound called THP (tetrahydropalmatine) that amplifies Ca2+ influx and potentiates NMDA receptors has been identified in the current study. In asthmatic human airway smooth muscle (HASM) cells, THP regulates the NMDA receptor and helps in asthmatic ASM contraction, and the pharmacological stimulation of ASM depends on both brain and respiratory NMDA receptors. Glutamate potency is altered by this substance without any voltage-dependent side effects. Additionally, a GGPP (geranylgeranyl pyrophosphate)-dependent mechanism of THP reduced the production of pro-inflammatory cytokines in ASM. THP is distinctive in terms of its chemical makeup, functioning, and agonist concentration-dependent and allosteric modulatory activity. To treat COVID-19-related SARS, THP, or any future-related compounds will make good drug-like molecule candidates.

Species comparison of compounds with known blood pressure effects in a vascular smooth muscle cell collagen contraction assay

INTRODUCTION

There is a great need for new approaches early in drug discovery that have the potential to improve clinical translation of compound-mediated cardiovascular effects. Current approaches frequently rely on in vivo animal models or in vitro tissue bath preparations, both of which are low throughput and costly. An in vitro surrogate screen for blood pressure using primary human cells may serve as a higher throughput method to quickly select compounds void of this secondary pharmacology and potentially improve late-stage drug development outcomes.

METHODS

In this study, we investigated 10 compounds with published in vivo blood pressure effects in a commercially available collagen contraction assay and evaluated rat, human, and canine (aortic) vascular smooth muscle cells (VSMCs). The aim of this study was to evaluate consistency between species and test their ability to predict the effects of known human vasodilators and constrictors. VSMCs were embedded at the same cell density in a collagen matrix which then floated freely in media containing test compounds. Collagen discs contracted faster than vehicle treated controls when incubated with a constrictor, and slower in the presence of a dilator.

RESULTS

Rat VSMCs responded as predicted of a VSMC-only culture to 9 out of 10 compounds. Human VSMCs responded as predicted to 8 out of 10 compounds, and canine VSMCs responded to 7 out of 10 compounds.

DISCUSSION

Our results suggest that rat VSMCs predict 90% of the effects of known vasoactive compounds in the collagen contraction assay while human and canine VSMCs were slightly less predictive (80% and 70%, respectively). Although blood pressure regulation is a multi-faceted and complex process, our data suggests the collagen smooth muscle contraction assay is useful as a qualitative early screen of compounds that act directly on smooth muscle cells of the arterial vasculature.

Vascular smooth muscle RhoA counteracts abdominal aortic aneurysm formation by modulating MAP4K4 activity

Whether a small GTPase RhoA plays a role in the pathology of abdominal aortic aneurysm (AAA) has not been determined. We show here that RhoA expression is reduced in human AAA lesions, compared with normal areas. Furthermore, incidence of AAA formation is increased in vascular smooth muscle cell (VSMC)-specific RhoA conditional knockout (cKO) mice. The contractility of the aortic rings and VSMCs from RhoA cKO mice is reduced, and expression of genes related to the VSMC contractility is attenuated by loss of RhoA. RhoA depletion activates the mitogen-activated protein (MAP) kinase signaling, including MAP4K4, in the aorta and VSMCs. Inhibition of MAP4K4 activity by DMX-5804 decreases AAA formation. Set, a binding protein to active RhoA, functions as an activator of MAP4K4 by sequestering PP2A, an inhibitor of MAP4K4, in the absence of RhoA. In conclusion, RhoA counteracts AAA formation through inhibition of MAP4K4 in cooperation with Set.

Asthmatic Eosinophils Promote Contractility and Migration of Airway Smooth Muscle Cells and Pulmonary Fibroblasts In Vitro

Enhanced contractility and migration of airway smooth muscle cells (ASMC) and pulmonary fibroblasts (PF) are part of airway remodeling in asthma. Eosinophils are the central inflammatory cells that participate in airway inflammation. However, the role of asthmatic eosinophils in ASMC and PF contractility, migration, and differentiation to contractile phenotype has not yet been precisely described. A total of 38 individuals were included in this study: 13 steroid-free non-severe allergic asthma (AA) patients, 11 severe non-allergic eosinophilic asthma (SNEA) patients, and 14 healthy subjects (HS). For AA patients and HS groups, a bronchial allergen challenge with D. pteronyssinus was performed. Individual combined cell cultures were prepared from isolated peripheral blood eosinophils and immortalized ASMC or commercial PF cell lines separately. The migration of ASMC and PF was evaluated using wound healing assay and contractility using collagen gel assay. Gene expression of contractile apparatus proteins, COL1A1, COL5A1, and FN, in ASMC and PF was evaluated using qRT-PCR. We found that contractility and migration of ASMC and PF significantly increased after incubation with asthmatic eosinophils compared to HS eosinophils, p < 0.05, and SNEA eosinophils demonstrated the highest effect on contractility of ASMC and migration of both cell lines, p < 0.05. AA and SNEA eosinophils significantly increased gene expression of contractile apparatus proteins, COL1A1 and FN, in both cell lines, p < 0.05. Furthermore, the allergen-activated AA eosinophils significantly increased the contractility of ASMC, and migration and gene expression in ASMC and PF, p < 0.05. Thus, asthmatic eosinophils change ASMC and PF behavior by increasing their contractility and migration, contributing to airway remodeling.

Respiratory syncytial virus induces β2-adrenergic receptor dysfunction in human airway smooth muscle cells

Pharmacologic agonism of the β₂-adrenergic receptor (β₂AR) induces bronchodilation by activating the enzyme adenylyl cyclase to generate cyclic adenosine monophosphate (cAMP). β₂AR agonists are generally the most effective strategy to relieve acute airway obstruction in asthmatic patients, but they are much less effective when airway obstruction in young patients is triggered by infection with respiratory syncytial virus (RSV). Here, we investigated the effects of RSV infection on the abundance and function of β₂AR in primary human airway smooth muscle cells (HASMCs) derived from pediatric lung tissue. We showed that RSV infection of HASMCs resulted in proteolytic cleavage of β₂AR mediated by the proteasome. RSV infection also resulted in β₂AR ligand-independent activation of adenylyl cyclase, leading to reduced cAMP synthesis compared to that in uninfected control cells. Last, RSV infection caused stronger airway smooth muscle cell contraction in vitro due to increased cytosolic Ca²⁺ concentrations. Thus, our results suggest that RSV infection simultaneously induces loss of functional β₂ARs and activation of multiple pathways favoring airway obstruction in young patients, with the net effect of counteracting β₂AR agonist-induced bronchodilation. These findings not only provide a potential mechanism for the reported lack of clinical efficacy of β₂AR agonists for treating virus-induced wheezing but also open the path to developing more precise therapeutic strategies.

Reduced pericyte and tight junction coverage in old diabetic rats are associated with hyperglycemia-induced cerebrovascular pericyte dysfunction

Diabetes mellitus (DM) is one of the primary pathological factors that contributes to aging-related cognitive impairments, but the underlying mechanisms remain unclear. We recently reported that old DM rats exhibited impaired myogenic responses of the cerebral arteries and arterioles, poor cerebral blood flow autoregulation, enhanced blood-brain barrier (BBB) leakage, and cognitive impairments. These changes were associated with diminished vascular smooth muscle cell contractile capability linked to elevated reactive oxygen species (ROS) and reduced ATP production. In the present study, using a nonobese T2DN DM rat, we isolated parenchymal arterioles (PAs), cultured cerebral microvascular pericytes, and examined whether cerebrovascular pericyte in DM is damaged and whether pericyte dysfunction may play a role in the regulation of cerebral hemodynamics and BBB integrity. We found that ROS and mitochondrial superoxide production were elevated in PAs isolated from old DM rats and in high glucose (HG)-treated α-smooth muscle actin-positive pericytes. HG-treated pericytes displayed decreased contractile capability in association with diminished mitochondrial respiration and ATP production. Additionally, the expression of advanced glycation end products, transforming growth factor-β, vascular endothelial growth factor, and fibronectin were enhanced, but claudin 5 and integrin β1 was reduced in the brain of old DM rats and HG-treated pericytes. Further, endothelial tight junction and pericyte coverage on microvessels were reduced in the cortex of old DM rats. These results demonstrate our previous findings that the impaired cerebral hemodynamics and BBB leakage and cognitive impairments in the same old DM model are associated with hyperglycemia-induced cerebrovascular pericyte dysfunction.NEW & NOTEWORTHY This study demonstrates that the loss of contractile capability in pericytes in diabetes is associated with enhanced ROS and reduced ATP production. Enhanced advanced glycation end products (AGEs) in diabetes accompany with reduced pericyte and endothelial tight junction coverage in the cortical capillaries of old diabetic rats. These results suggest our previous findings that the impaired cerebral hemodynamics, BBB leakage, and cognitive impairments in old DM model are associated with hyperglycemia-induced cerebrovascular pericyte dysfunction.

Tensin1 expression and function in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) constitutes a major cause of morbidity and mortality. Genome wide association studies have shown significant associations between airflow obstruction or COPD with a non-synonymous SNP in the TNS1 gene, which encodes tensin1. However, the expression, cellular distribution and function of tensin1 in human airway tissue and cells are unknown. We therefore examined these characteristics in tissue and cells from controls and people with COPD or asthma. Airway tissue was immunostained for tensin1. Tensin1 expression in cultured human airway smooth muscle cells (HASMCs) was evaluated using qRT-PCR, western blotting and immunofluorescent staining. siRNAs were used to downregulate tensin1 expression. Tensin1 expression was increased in the airway smooth muscle and lamina propria in COPD tissue, but not asthma, when compared to controls. Tensin1 was expressed in HASMCs and upregulated by TGFβ1. TGFβ1 and fibronectin increased the localisation of tensin1 to fibrillar adhesions. Tensin1 and α-smooth muscle actin (αSMA) were strongly co-localised, and tensin1 depletion in HASMCs attenuated both αSMA expression and contraction of collagen gels. In summary, tensin1 expression is increased in COPD airways, and may promote airway obstruction by enhancing the expression of contractile proteins and their localisation to stress fibres in HASMCs.

Functional characterization of 3D contractile smooth muscle tissues generated using a unique microfluidic 3D bioprinting technology

Conditions such as asthma and inflammatory bowel disease are characterized by aberrant smooth muscle contraction. It has proven difficult to develop human cell-based models that mimic acute muscle contraction in 2D in vitro cultures due to the nonphysiological chemical and mechanical properties of lab plastics that do not allow for muscle cell contraction. To enhance the relevance of in vitro models for human disease, we describe how functional 3D smooth muscle tissue that exhibits physiological and pharmacologically relevant acute contraction and relaxation responses can be reproducibly fabricated using a unique microfluidic 3D bioprinting technology. Primary human airway and intestinal smooth muscle cells were printed into rings of muscle tissue at high density and viability. Printed tissues contracted to physiological concentrations of histamine (0.01-100 μM) and relaxed to salbutamol, a pharmacological compound used to relieve asthmatic exacerbations. The addition of TGFβ to airway muscle rings induced an increase in unstimulated muscle shortening and a decreased response to salbutamol, a phenomenon which also occurs in chronic lung diseases. Results indicate that the 3D bioprinted smooth muscle is a physiologically relevant in vitro model that can be utilized to study disease pathways and the effects of novel therapeutics on acute contraction and chronic tissue stenosis.

Secretory immunoglobulin A induces human lung fibroblasts to produce inflammatory cytokines and undergo activation

Immunoglobulin (Ig)A is the most abundant immunoglobulin in humans, and in the airway mucosa secretory IgA (sIgA) plays a pivotal role in first-line defense against invading pathogens and antigens. IgA has been reported to also have pathogenic effects, including possible worsening of the prognosis of idiopathic pulmonary fibrosis (IPF). However, the precise effects of IgA on lung fibroblasts remain unclear, and we aimed to elucidate how IgA activates human lung fibroblasts. We found that sIgA, but not monomeric IgA (mIgA), induced interleukin (IL)-6, IL-8, monocyte chemoattractant protein (MCP)-1 and granulocyte-macrophage colony-stimulating factor (GM-CSF) production by normal human lung fibroblasts (NHLFs) at both the protein and mRNA levels. sIgA also promoted proliferation of NHLFs and collagen gel contraction comparable to with transforming growth factor (TGF)-β, which is involved in fibrogenesis in IPF. Also, Western blot analysis and real-time quantitative polymerase chain reaction (PCR) revealed that sIgA enhanced production of α-smooth muscle actin (α-SMA) and collagen type I (Col I) by NHLFs. Flow cytometry showed that NHLFs bound sIgA, and among the known IgA receptors, NHLFs significantly expressed CD71 (transferrin receptor). Transfection of siRNA targeting CD71 partially but significantly suppressed cytokine production by NHLFs co-cultured with sIgA. Our findings suggest that sIgA may promote human lung inflammation and fibrosis by enhancing production of inflammatory or fibrogenic cytokines as well as extracellular matrix, inducing fibroblast differentiation into myofibroblasts and promoting human lung fibroblast proliferation. sIgA's enhancement of cytokine production may be due partially to its binding to CD71 or the secretory component.

Extracellular ubiquitin modulates cardiac fibroblast phenotype and function via its interaction with CXCR4

AIMS

β-adrenergic receptor (β-AR) stimulation increases extracellular levels of ubiquitin (UB), and exogenous UB plays an important role in β-AR-stimulated myocardial remodeling with effects on heart function, fibrosis and myocyte apoptosis. Cardiac fibroblasts are vital for maintaining the normal function of the heart, and in the structural remodeling of the heart in response to injury. Here we hypothesized that extracellular UB modulates cardiac fibroblast phenotype and function via its interaction with CXC chemokine receptor type 4 (CXCR4).

MAIN METHODS

Serum starved adult cardiac fibroblasts were used to identify CXCR4 as a receptor for UB. Fluorescent microscopy, co-immunoprecipitation, western blot, proliferation, migration and collagen contraction assays were performed to investigate the role of UB/CXCR4 axis on cell signaling, and modulation of fibroblast phenotype and function.

KEY FINDINGS

Using fluorescent microscopy and co-immunoprecipitation assay, we provide evidence that extracellular UB interacts with CXCR4. CXCR4 antagonist, AMD3100, inhibited interaction of UB with CXCR4. UB activated ERK1/2, not Akt. It enhanced VEGF-A expression, while decreasing β3 integrins expression. Two mutated UB proteins (V70A and F4A; unable to interact with CXCR4) failed to affect the expression of VEGF-A and β3 integrins. UB treatment inhibited migration of cells into the wound and FBS-stimulated cell proliferation. UB enhanced expression of α-smooth muscle actin (marker of myofibroblast differentiation) and contraction of fibroblast-populated collagen gel pads. Most of the effects of UB were negated by AMD3100.

SIGNIFICANCE

The data presented here suggest that UB interacts with CXCR4, and UB/CXCR4 interaction affects intracellular signaling, and modulates fibroblast phenotype and function.

Emerging Biotechnology Applications of Aqueous Two-Phase Systems

Liquid-liquid phase separation between aqueous solutions containing two incompatible polymers, a polymer and a salt, or a polymer and a surfactant, has been exploited for a wide variety of biotechnology applications throughout the years. While many applications for aqueous two-phase systems fall within the realm of separation science, the ability to partition many different materials within these systems, coupled with recent advances in materials science and liquid handling, has allowed bioengineers to imagine new applications. This progress report provides an overview of the history and key properties of aqueous two-phase systems to lend context to how these materials have progressed to modern applications such as cellular micropatterning and bioprinting, high-throughput 3D tissue assembly, microscale biomolecular assay development, facilitation of cell separation and microcapsule production using microfluidic devices, and synthetic biology. Future directions and present limitations and design considerations of this adaptable and promising toolkit for biomolecule and cellular manipulation are further evaluated.

An impedance-based cell contraction assay using human primary smooth muscle cells and fibroblasts

INTRODUCTION

Many cell types (including muscle cells and fibroblasts) can contract at physiological conditions and their contractility may change during tissue injury and repair or other diseases such as allergy and asthma. The conventional gel contraction assay is commonly used to monitor the cellular contractility. It is a manual assay and the experiment usually takes hours even days to complete. As its readout is not always accurate and reliable, the gel contraction assay is often used to qualitatively (but not quantitatively) characterize cellular contractility under various conditions.

METHOD

To overcome the limits of the gel contraction assay, we developed an impedance-based contraction assay using the xCELLigence RTCA MP system. This technology utilizes special 96-well E-plates with gold microelectrode arrays printed in individual wells to monitor cellular adhesion by recording the electrical impedance in real time. The impedance change (percentage vs. control) can be used as the readout for cellular contraction.

RESULTS

We demonstrated that the impedance-based contraction assay can be performed within 2h. Using this new method, we quantitatively characterized the effects of several contractile stimulators and inhibitors on human primary bronchial smooth muscle cells and primary lung fibroblasts.

DISCUSSION

The impedance-based contraction assay can be applied to both basic research and drug discovery for characterizing cellular contraction quantitatively. Because it has high throughput capacity and high reproducibility, the impedance-based contraction assay is useful for high throughput functional screening in drug industry.

Neural stem/progenitor cells on collagen with anchored basic fibroblast growth factor as potential natural nerve conduits for facial nerve regeneration

Introducing neural stem/progenitor cells (NS/PCs) for repairing facial nerve injuries could be an alternative strategy for nerve gap reconstruction. However, the lack of success associated with current methods of applying NS/PCs to neurological disease is due to poor engraftment following transplantation into the host tissue. In this work, we developed rat-tail collagen-based nerve conduits to repair lengthy facial nerve defects, promoting NS/PC proliferation in the natural nerve conduits with anchored bFGF to improve the therapeutic effects of cell transplantation. In vitro studies showed that heparinized collagen prevented leakage of bFGF and NS/PCs expended in the rat-tail collagen gel with the anchored bFGF. The natural nerve conduits were implanted to connect 8-mm facial nerve defects in rats. The repair outcomes including vibrissae movements, electrophysiological tests, immunohistochemistry and remyelination analysis of regenerated nerve were evaluated. At 12weeks after implantation, only natural nerve conduits treated group showed Hoechst labeled NS/PCs. Besides, the natural nerve conduit significantly promoted functional recovery and nerve growth, which was similar to those of the gold standard, an autograft. The animal experiment results suggesting that the natural nerve conduits were valuable for facial nerve reconstruction.

STATEMENT OF SIGNIFICANCE

Neural stem/progenitor cells (NS/PCs) were beneficial for the treatment of nervous system diseases. However, after transplantation, the beneficial was limited because the number of living NS/PCs decreased rapidly due to insufficient signaling molecules, such as growth factors, in the microenvironments surrounding transplanted cells. In the present study, we constructed collagen-based nerve conduit with anchored bFGF to achieve higher numbers of NS/PCs for repairing facial nerve injury. Compared with other methods involving neutral salt treatment or dialysis, the fabrication method of collagen scaffolds was simple, low-cost and safe, requiring a relatively short time to prepare. At 12weeks after transplantation, the functional and histological results of natural nerve conduits treated group showed significant similarities to the gold standard method of nerve autografting.