House dust mite and Th2 cytokine-mediated epithelial barrier dysfunction attenuation by KL001 in 16-HBE cells.

House dust mite (HDM) is a common aeroallergen that can disrupt the airway epithelial barrier leading to dysregulated immune response, resulting in allergic lung diseases such as asthma. Cryptochrome (CRY), a circadian clock gene, plays an important role in the regulation of metabolism, and immune response. It remains unclear whether stabilizing CRY using KL001 can attenuate HDM/Th2 cytokine-induced epithelial barrier dysfunction in 16-HBE cells. We evaluate the effect of KL001 (20 µM) pre-treatment (4 hrs) in HDM/Th2 cytokine (IL-4 or IL-13)-mediated change in epithelial barrier function. HDM and Th2 cytokine-induced changes in transepithelial electrical resistance (TEER) were determined by an xCELLigence real-time cell analyzer and delocalization of adherens junction complex (AJC: E-cadherin and ß-catenin) and tight junction proteins (TJP: Occludin and Zonula occludens-1) by immunostaining and confocal microscopy. Finally, quantitative real-time PCR (qRT-PCR) and Western blotting were used to measure altered gene expression and protein abundance of the epithelial barrier function and core clock genes, respectively. HDM and Th2 cytokine treatment significantly decreased TEER associated with altered gene expression and protein abundance of the selected epithelial barrier function and circadian clock genes. However, pre-treatment with KL001 attenuated HDM and Th2 cytokine-induced epithelial barrier dysfunction as early as 12-24 hrs. KL001 pre-treatment showed attenuation of HDM and Th2 cytokine-induced alteration in the localization and gene expression of AJP and TJP (Cdh1, Ocln, and Zo1) and core clock genes (Clock, Arntl/Bmal1, Cry1/2, Per1/2, Nr1d1/Rev-erbα, and Nfil3). We demonstrate, for the first time, the protective role of KL001 in HDM and Th2 cytokine-mediated epithelial barrier dysfunction.

Acute HDM exposure shows time-of-day and sex-based differences in the severity of lung inflammation and circadian clock disruption.

Background: Asthma is a chronic inflammatory disease that shows a time-of-day response to variations in symptoms/severity. However, how the lung circadian clock influences time-of-day response and sex-based differences in house dust mite (HDM)-induced airway inflammation and remodeling has not been thoroughly investigated. Objective: We sought to determine whether acute HDM exposure in wild-type mice shows time-of-day response and sex-based differences in allergic airway inflammation and circadian clock disruption in the lungs. Methods: Wild-type (C57BL/6J) and Rev-erbα knockout (KO) mice were exposed to either PBS or HDM (for 10 days) intranasally at Zeitgeber time (ZT0: 6 am; ZT12: 6 pm) and euthanized 48 hours after the last exposure. Acute HDM-induced time-of-day response and sex-based differences in lung inflammation, gated cytokines/chemokines, humoral and hormonal responses, and circadian clock gene expression were analyzed. Results: Acute HDM-exposed mice showed a time-of-day response and sex-based differences in exaggerated lung inflammation (inflammatory eosinophils and interstitial macrophages) at ZT12 when compared with ZT0. HDM-exposed female mice showed increased inflammatory response at ZT12, but HDM-exposed male mice showed comparatively lower inflammation with no time-of-day response. HDM-exposed female and male mice showed augmented IgE levels at ZT12 when compared with ZT0. Myeloid innate immunity panel, cytokines/chemokines, and mucin genes showed a time-of-day gating response at ZT0 and ZT12 in the HDM group. In addition, HDM exposure altered the expression of circadian clock genes in the lung, which was evident in female mice at ZT12. Overall, female mice showed significant time-of-day responses to all these parameters compared with male mice. Rev-erbα KO mice exposed to acute HDM showed exaggerated lung inflammation associated with increased IgE and proinflammatory cytokines in bronchoalveolar lavage fluid. Interestingly, HDM exposure causes reduced expression of clock genes in flow-sorted resident eosinophils but not alveolar macrophages. Acute HDM exposure reduced the nocturnal locomotor activity in mice 5 days post-HDM exposure until day 10. Conclusions: This study shows a time-of-day response to acute HDM exposure and sex-based differences in the severity of lung inflammation and humoral immune response associated with circadian clock disruption. Our findings support the use of separate female and male mice cohorts for preclinical studies to understand the molecular heterogeneity in asthma pathophysiology.

Chronic HDM exposure shows time-of-day and sex-based differences in inflammatory response associated with lung circadian clock disruption.

Circadian rhythms and sex differences are involved in the pathophysiology of asthma. Yet, there are no reports that simultaneously address the role of the circadian clock and sex-based differences in chronic house dust mite (HDM)-induced asthma. Here, we sought to determine if chronic HDM exposure during the resting phase (zeitgeber time: ZT0/6:00 a.m.) versus the active phase (ZT12/6:00 p.m.) differentially affects the circadian clock and alters asthma pathobiology in female and male mice. HDM exposure at ZT12 exaggerated infiltration of eosinophil subtypes and associated chemokines in females compared to males. Furthermore, HDM exposure augmented eosinophil chemokines, Th2 gene expression and cytokine release, and humoral immune response in females compared to males at ZT12. Concurrently, histopathological evaluation confirmed increased airway inflammation at ZT12 in both females and males. Overall, we showed a time-of-day response and sex-based differences in HDM-induced exaggerated asthmatic phenotypes (inflammation/remodeling) and circadian clock disruption in females compared to males.

A discrete Huber-Braun neuron model: from nodal properties to network performance.

Many of the well-known neuron models are continuous time systems with complex mathematical definitions. Literatures have shown that a discrete mathematical model can effectively replicate the complete dynamical behaviour of a neuron with much reduced complexity. Hence, we propose a new discrete neuron model derived from the Huber-Braun neuron with two additional slow and subthreshold currents alongside the ion channel currents. We have also introduced temperature dependent ion channels to study its effects on the firing pattern of the neuron. With bifurcation and Lyapunov exponents we showed the chaotic and periodic regions of the discrete model. Further to study the complexity of the neuron model, we have used the sample entropy algorithm. Though the individual neuron analysis gives us an idea about the dynamical properties, it's the collective behaviour which decides the overall behavioural pattern of the neuron. Hence, we investigate the spatiotemporal behaviour of the discrete neuron model in single- and two-layer network. We have considered obstacle as an important factor which changes the excitability of the neurons in the network. Literatures have shown that spiral waves can play a positive role in breaking through quiescent areas of the brain as a pacemaker by creating a coherence resonance behaviour. Hence, we are interested in studying the induced spiral waves in the network. In this condition when an obstacle is introduced the wave propagation is disturbed and we could see multiple wave re-entry and spiral waves. In a two-layer network when the obstacle is considered only in one layer and stimulus applied to the layer having the obstacle, the wave re-entry is seen in both the layer though the other layer is not exposed to obstacle. But when both the layers are inserted with an obstacle and stimuli also applied to the layers, they behave like independent layers with no coupling effect. In a two-layer network, stimulus play an important role in spatiotemporal dynamics of the network. Supplementary Information: The online version contains supplementary material available at 10.1007/s11571-022-09806-1.

Strange nonchaotic dynamics in a discrete FitzHugh-Nagumo neuron model with sigmoidal recovery variable.

We report the appearance of strange nonchaotic attractors in a discrete FitzHugh-Nagumo neuron model with discontinuous resetting. The well-known strange nonchaotic attractors appear in quasiperiodically forced continuous-time dynamical systems as well as in a discrete map with a small intensity of noise. Interestingly, we show that a discrete FitzHugh-Nagumo neuron model with a sigmoidal recovery variable and discontinuous resetting generates strange nonchaotic attractors without external force. These strange nonchaotic attractors occur as intermittency behavior (locally unstable behavior in laminar flow) in the periodic dynamics. We use various characterization techniques to validate the existence of strange nonchaotic attractors in the considered system.

Dynamical effects of hypergraph links in a network of fractional-order complex systems.

In recent times, the fractional-order dynamical networks have gained lots of interest across various scientific communities because it admits some important properties like infinite memory, genetic characteristics, and more degrees of freedom than an integer-order system. Because of these potential applications, the study of the collective behaviors of fractional-order complex networks has been investigated in the literature. In this work, we investigate the influence of higher-order interactions in fractional-order complex systems. We consider both two-body and three-body diffusive interactions. To elucidate the role of higher-order interaction, we show how the network of oscillators is synchronized for different values of fractional-order. The stability of synchronization is studied with a master stability function analysis. Our results show that higher-order interactions among complex networks help the earlier synchronization of networks with a lesser value of first-order coupling strengths in fractional-order complex simplices. Besides that, the fractional-order also shows a notable impact on synchronization of complex simplices. For the lower value of fractional-order, the systems get synchronized earlier, with lesser coupling strengths in both two-body and three-body interactions. To show the generality in the outcome, two neuron models, namely, Hindmarsh-Rose and Morris-Leccar, and a nonlinear Rössler oscillator are considered for our analysis.

Effect of magnetic induction on the synchronizability of coupled neuron network.

Master stability functions (MSFs) are significant tools to identify the synchronizability of nonlinear dynamical systems. For a network of coupled oscillators to be synchronized, the corresponding MSF should be negative. The study of MSF will normally be discussed considering the coupling factor as a control variable. In our study, we considered various neuron models with electromagnetic flux induction and investigated the MSF's zero-crossing points for various values of the flux coupling coefficient. Our numerical analysis has shown that in all the neuron models we considered, flux coupling has increased the synchronization of the coupled neuron by increasing the number of zero-crossing points of MSFs or by achieving a zero-crossing point for a lesser value of a coupling parameter.

Noise induced suppression of spiral waves in a hybrid FitzHugh-Nagumo neuron with discontinuous resetting.

A modified FitzHugh-Nagumo neuron model with sigmoid function-based recovery variable is considered with electromagnetic flux coupling. The dynamical properties of the proposed neuron model are investigated, and as the excitation current becomes larger, the number of fixed points decreases to one. The bifurcation plots are investigated to show the chaotic and periodic regimes for various values of excitation current and parameters. A N×N network of the neuron model is constructed to study the wave propagation and wave re-entry phenomena. Investigations are conducted to show that for larger flux coupling values, the spiral waves are suppressed, but for such values of the flux coupling, the individual nodes are driven into periodic regimes. By introducing Gaussian noise as an additional current term, we showed that when noise is introduced for the entire simulation time, the dynamics of the nodes are largely altered while the noise exposure for 200-time units will not alter the dynamics of the nodes completely.

Recent updates on the role of extracellular vesicles in the pathogenesis of allergic asthma.

Asthma is a chronic inflammatory disease of the airway diagnosed with different endotypes and phenotypes, characterized by airway obstruction in response to allergens, bacterial/viral infections, or pollutants. Several cell types such as the airway epithelial cells, mesenchymal stem cells and different immune cells including dendritic cells (DCs), T and B cells and mast cells play an essential role during the pathobiology of asthma. Extracellular vesicles (EVs) are membranous nanovesicles produced by every cell type that facilitates intercellular communications. EVs contain heterogeneous cargos that primarily depend on the composition or cell type of origin and they can alter the physiological state of the target cells. EVs encompass a wide variety of proteins including Tetraspanins, MHC classes I and II, co-stimulatory molecules, nucleic acids such as RNA, miRNA, piRNA, circRNA, and lipids like ceramides and sphingolipids. Recent literature indicates that EVs play a pivotal role in the pathophysiology of allergic asthma and may potentially be used as a novel biomarker to determine endotypes and phenotypes in severe asthmatics. Based on the prior reports, we speculate that regulation of EVs biogenesis and release might be under the control of circadian rhythms. Thus, circadian rhythms may influence the composition of the EVs, which alter the microenvironment that results in the induction of an immune-inflammatory response to various environmental insults or allergens such as air pollutants, ozone, diesel exhaust particles, pollens, outdoor molds, environmental tobacco smoke, etc. In this mini-review, we summarize the recent updates on the novel role of EVs in the pathogenesis of asthma, and highlight the link between circadian rhythms and EVs that may be important to identify molecular mechanisms to target during the pathogenesis of chronic inflammatory lung disease such as asthma.

COVID-19: Sleep, Circadian Rhythms and Immunity - Repurposing Drugs and Chronotherapeutics for SARS-CoV-2.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has affected nearly 28 million people in the United States and has caused more than five hundred thousand deaths as of February 21, 2021. As the novel coronavirus continues to take its toll in the United States and all across the globe, particularly among the elderly (>65 years), clinicians and translational researchers are taking a closer look at the nexus of sleep, circadian rhythms and immunity that may contribute toward a more severe coronavirus disease-19 (COVID-19). SARS-CoV-2-induced multi-organ failure affects both central and peripheral organs, causing increased mortality in the elderly. However, whether differences in sleep, circadian rhythms, and immunity between older and younger individuals contribute to the age-related differences in systemic dysregulation of target organs observed in SARS-CoV-2 infection remain largely unknown. Current literature demonstrates the emerging role of sleep, circadian rhythms, and immunity in the development of chronic pulmonary diseases and respiratory infections in human and mouse models. The exact mechanism underlying acute respiratory distress syndrome (ARDS) and other cardiopulmonary complications in elderly patients in combination with associated comorbidities remain unclear. Nevertheless, understanding the critical role of sleep, circadian clock dysfunction in target organs, and immune status of patients with SARS-CoV-2 may provide novel insights into possible therapies. Chronotherapy is an emerging concept that is gaining attention in sleep medicine. Accumulating evidence suggests that nearly half of all physiological functions follow a strict daily rhythm. However, healthcare professionals rarely take implementing timed-administration of drugs into consideration. In this review, we summarize recent findings directly relating to the contributing roles of sleep, circadian rhythms and immune response in modulating infectious disease processes, and integrate chronotherapy in the discussion of the potential drugs that can be repurposed to improve the treatment and management of COVID-19.

Targeting the Nrf2/ARE Signalling Pathway to Mitigate Isoproterenol-Induced Cardiac Hypertrophy: Plausible Role of Hesperetin in Redox Homeostasis.

Cardiac hypertrophy is the underlying cause of heart failure and is characterized by excessive oxidative stress leading to collagen deposition. Therefore, understanding the signalling mechanisms involved in excessive extracellular matrix deposition is necessary to prevent cardiac remodelling and heart failure. In this study, we hypothesized that hesperetin, a flavanone that elicits the activation of Nrf2 signalling and thereby suppresses oxidative stress, mediated pathological cardiac hypertrophy progression. A cardiac hypertrophy model was established with subcutaneous injection of isoproterenol in male Wistar rats. Oxidative stress markers, antioxidant defense status, and its upstream signalling molecules were evaluated to discover the impacts of hesperetin in ameliorating cardiac hypertrophy. Our results implicate that hesperetin pretreatment resulted in the mitigation of oxidative stress by upregulating antioxidant capacity of the heart. This curative effect might be owing to the activation of the master regulator of antioxidant defense system, known as Nrf2. Further, analysis of Nrf2 revealed that hesperetin enhances its nuclear translocation as well as the expression of its downstream targets (GCLC, NQO1, and HO-1) to boost the antioxidative status of the cells. To support this notion, in vitro studies were carried out in isoproterenol-treated H9c2 cells. Immunocytochemical analysis showed augmented nuclear localization of Nrf2 implicating the action of hesperetin at the molecular level to maintain the cellular redox homeostasis. Thus, it is conceivable that hesperetin could be a potential therapeutic candidate that enhances Nrf2 signalling and thereby ameliorates pathological cardiac remodelling.

Role of Nrf2 dysfunction in the pathogenesis of diabetic nephropathy: Therapeutic prospect of epigallocatechin-3-gallate.

Diabetic nephropathy (DN), a progressive kidney disease afflicts more than 20 and up to 40% of the diabetic population and it is characterized by persistent microalbuminuria declined glomerular filtration rate. The interesting feature associated with DN is that, even though the progression of the disease correlates with oxidative stress, Nrf2, the master regulator of antioxidant defense system involved in counteracting oxidative stress is also upregulated in the diabetic kidneys of both human as well as experimental animals in early stages of DN. Despite the increased expression, the ability of this protein to get translocated into the nucleus is diminished signifying the functional impairment of Nrf2, implying redox imbalance. Hence, it is understood that agents that boost the translocation of Nrf2 might be beneficial rather than those that quantitatively overexpress Nrf2 in treating DN. The deleterious effects of synthetic Nrf2 activators have instigated the researchers to search for phytochemicals that have ambient Nrf2 boosting ability with no side effects, one such phytochemical is Epigallocatechin-3-gallate (EGCG) and it has shown beneficial effects by preventing the progression of DN via influencing Nrf2/ARE pathway, however, the modus operandi is unclear, despite speculations. This study was designed to find out whether supplementation of Nrf2 booster like EGCG at the crucial time of Nrf2 dysfunction can mitigate the progression of DN. Based on the findings of the present study, it might be concluded that the beneficial effect of EGCG in mitigating DN is mediated mainly through its ability to activate the Nrf2/ARE signaling pathway at multiple stages i.e., by downregulating Keap1 and boosting the nuclear Nrf2 level by disrupting Nrf2-Keap1 interaction. These results emphasize that supplementation of EGCG might be more beneficial at an early stage of DN, where dysfunctional Nrf2 accumulation occurs, which should be further validated.

Evaluation of antiviral T cell responses and TSCM cells in volunteers enrolled in a phase I HIV-1 subtype C prophylactic vaccine trial in India.

T cells play an important role in controlling viral replication during HIV infection. An effective vaccine should, therefore, lead to the induction of a strong and early viral-specific CD8+ T cell response. While polyfunctional T cell responses are thought to be important contributors to the antiviral response, there is evidence to show that polyfunctional HIV- specific CD8+ T cells are just a small fraction of the total HIV-specific CD8+ T cells and may be absent in many individuals who control HIV replication, suggesting that other HIV-1 specific CD8+ effector T cell subsets may be key players in HIV control. Stem cell-like memory T cells (TSCM) are a subset of T cells with a long half-life and self-renewal capacity. They serve as key reservoirs for HIV and contribute a significant barrier to HIV eradication. The present study evaluated vaccine-induced antiviral responses and TSCM cells in volunteers vaccinated with a subtype C prophylactic HIV-1 vaccine candidate administered in a prime-boost regimen. We found that ADVAX DNA prime followed by MVA boost induced significantly more peripheral CD8+ TSCM cells and higher levels of CD8+ T cell-mediated inhibition of replication of different HIV-1 clades as compared to MVA alone and placebo. These findings are novel and provide encouraging evidence to demonstrate the induction of TSCM and cytotoxic immune responses by a subtype C HIV-1 prophylactic vaccine administered using a prime-boost strategy.

Morinda citrifolia and Its Active Principle Scopoletin Mitigate Protein Aggregation and Neuronal Apoptosis through Augmenting the DJ-1/Nrf2/ARE Signaling Pathway.

Given the role of oxidative stress in PD pathogenesis and off-target side effects of currently available drugs, several natural phytochemicals seem to be promising in the management of PD. Here, we tested the hypothesis that scopoletin, an active principle obtained from Morinda citrifolia (MC), efficiently quenches oxidative stress through DJ-1/Nrf2 signaling and ameliorates rotenone-induced PD. Despite reducing oxidative stress, the administration of MC extract (MCE) has lessened protein aggregation as evident from decreased levels of nitrotyrosine and α-synuclein. In vitro studies revealed that scopoletin lessened rotenone-induced apoptosis in SH-SY5Y cells through preventing oxidative injury. Particularly, scopoletin markedly upregulated DJ-1, which then promoted the nuclear translocation of Nrf2 and transactivation of antioxidant genes. Furthermore, we found that scopoletin prevents the nuclear exportation of Nrf2 by reducing the levels of Keap1 and thereby enhancing the neuronal defense system. Overall, our findings suggest that scopoletin acts through DJ-1-mediated Nrf2 signaling to protect the brain from rotenone-induced oxidative stress and PD. Thus, we postulate that scopoletin could be a potential drug to treat PD.

Amelioration of apoptotic events in the skeletal muscle of intra-nigrally rotenone-infused Parkinsonian rats by Morinda citrifolia--up-regulation of Bcl-2 and blockage of cytochrome c release.

Parkinson's disease is a progressive neurodegenerative movement disorder with the cardinal symptoms of bradykinesia, resting tremor, rigidity, and postural instability, which lead to abnormal movements and lack of activity, which in turn cause muscular damage. Even though studies have been carried out to elucidate the causative factors that lead to muscular damage in Parkinson's disease, apoptotic events that occur in the skeletal muscle and a therapeutical approach to culminate the muscular damage have not been extensively studied. Thus, this study evaluates the impact of rotenone-induced SNPc lesions on skeletal muscle apoptosis and the efficacy of an ethyl acetate extract of Morinda citrifolia in safeguarding the myocytes. Biochemical assays along with apoptotic markers studied by immunoblot and reverse transcription-polymerase chain reaction in the current study revealed that the supplementation of Morinda citrifolia significantly reverted alterations in both biochemical and histological parameters in rotenone-infused PD rats. Treatment with Morinda citrifolia also reduced the expression of pro-apoptotic proteins Bax, caspase-3 and caspase-9 and blocked the release of cytochrome c from mitochondria induced by rotenone. In addition, it augmented the expression of Bcl2 both transcriptionally and translationally. Thus, this preliminary study paves a way to show that the antioxidant and anti-apoptotic activities of Morinda citrifolia can be exploited to alleviate skeletal muscle damage induced by Parkinsonism.

EGCG mediated downregulation of NF-AT and macrophage infiltration in experimental hepatic steatosis.

SCOPE: Increased fat consumption in industrialized countries has resulted in hepatic steatosis that upregulates atherogenic aspirant genes, leading to atherosclerosis and mortality. Although extensive studies have been carried out to elucidate the atheroprotective efficacy of epigallocatechin-3-gallate (EGCG), the effect of EGCG on hepatic steatosis has not been studied comprehensively. Hence, the current study was designed to find out the effect of EGCG on hepatic events that prelude atherosclerosis with special reference to macrophage infiltration. METHODS AND RESULTS: Male albino rats of Wistar strain were used in this study. Basic biochemical assays along with the protein expression of CAMs, NF-κB, TNF-α and NF-AT were assayed in the current study. EGCG supplementation significantly reverted the alterations in both biochemical and histological parameters and is shown to reduce the TNF-α mediated NF-AT expression and thereby its downstream targets like ICAM-1 and E-selectin expression to a greater extent than NF-κB mediated downstream targets like VCAM-1 and P-selectin in hypercholesterolemic rat liver. CONCLUSION: Our results suggest that EGCG influences the early events of atherosclerosis that occur; thereby modulating the NF-AT pathway and thereby mitigating the hypercholesterolemic stress.

Epigallocatechin-3-gallate restores the Bcl-2 expression in liver of young rats challenged with hypercholesterolemia but not in aged rats: an insight into its disparity of efficacy on advancing age.

Advanced age significantly increases cholesterol levels, however, when combined with a high cholesterol diet it not only leads to life-threatening conditions like atherosclerosis, but also plays a central role in the pathogenesis of hepatic damage and its complications. Even though extensive studies have been carried out to elucidate the causative factors that lead to hepatic steatosis associated with liver damage in young rats due to hypercholesterolemia, events that occur in aged rats where a different milieu is presented by up and down regulation of various genes co-existing, has not been extensively studied. Hence, this study comparatively evaluates the impact of hypercholesterolemic stress induced liver damage in young and aged rats and the efficacy of epigallocatechin-3-gallate to protect the liver in both young and aged rats with special reference to apoptosis. Moreover, the work has been designed to investigate whether aged rats act as better models for studying the efficacy of atheroprotective drugs. Male albino rats of the Wistar strain were used in this study. Basic biochemical assays along with apoptotic markers assayed in the current study revealed that treatment with EGCG significantly reverted the alterations in both biochemical and histological parameters in young and aged hypercholesterolemic rats when compared to their respective controls. However, the extent of reversion was far superior in young rats, when compared to aged rats. EGCG reduced hepatic Bax expression in both young and aged hypercholesterolemic rats. On the other hand, Bcl-2 expression was up regulated significantly in young hypercholesterolemic rats, but not in aged hypercholesterolemic rats on treatment with EGCG. This throws light on the efficacy of the treatment differing in young and aged rats as well; atheroprotective drugs shall be tested for their efficacy in aged hypercholesterolemic models.