BRD9 regulates interferon-stimulated genes during macrophage activation via cooperation with BET protein BRD4

Macrophages induce a number of inflammatory response genes in response to stimulation with microbial ligands. In response to endotoxin Lipid A, a gene-activation cascade of primary followed by secondary-response genes is induced. Epigenetic state is an important regulator of the kinetics, specificity, and mechanism of gene activation of these two classes. In particular, SWI/SNF chromatin-remodeling complexes are required for the induction of secondary-response genes, but not primary-response genes, which generally exhibit open chromatin. Here, we show that a recently discovered variant of the SWI/SNF complex, the noncanonical BAF complex (ncBAF), regulates secondary-response genes in the interferon (IFN) response pathway. Inhibition of bromodomain-containing protein 9 (BRD9), a subunit of the ncBAF complex, with BRD9 bromodomain inhibitors (BRD9i) or a degrader (dBRD9) led to reduction in a number of interferon-stimulated genes (ISGs) following stimulation with endotoxin lipid A. BRD9-dependent genes overlapped highly with a subset of genes differentially regulated by BET protein inhibition with JQ1 following endotoxin stimulation. We find that the BET protein BRD4 is cobound with BRD9 in unstimulated macrophages and corecruited upon stimulation to ISG promoters along with STAT1, STAT2, and IRF9, components of the ISGF3 complex activated downstream of IFN-alpha receptor stimulation. In the presence of BRD9i or dBRD9, STAT1-, STAT2-, and IRF9-binding is reduced, in some cases with reduced binding of BRD4. These results demonstrate a specific role for BRD9 and the ncBAF complex in ISG activation and identify an activity for BRD9 inhibitors and degraders in dampening endotoxin- and IFN-dependent gene expression.

Syk-MyD88 Axis Is a Critical Determinant of Inflammatory-Response in Activated Macrophages

BackgroundInflammation, a vital immune response to infection and injury, is mediated by macrophage activation. While spleen tyrosine kinase (Syk) and myeloid differentiation primary response 88 (MyD88) are reportedly involved in inflammatory responses in macrophages, their roles and underlying mechanisms are largely unknown.MethodsHere, the role of the MyD88-Syk axis and the mechanism by which Syk and MyD88 cooperate during macrophage-mediated inflammatory responses are explored using knockout conditions of these proteins and mutation strategy as well as flowcytometric and immunoblotting analyses.ResultsSyk rapidly activates the nuclear factor-kappa B (NF-κB) signaling pathway in lipopolysaccharide (LPS)-stimulated RAW264.7 cells, and the activation of the NF-κB signaling pathway is abolished in Syk−/− RAW264.7 cells. MyD88 activates Syk and Syk-induced activation of NF-κB signaling pathway in LPS-stimulated RAW264.7 cells but Syk-induced inflammatory responses are significantly inhibited in MyD88−/− RAW264.7 cells. MyD88 interacts with Syk through the tyrosine 58 residue (Y58) in the hemi-immunoreceptor tyrosine-based activation motif (ITAM) of MyD88, leading to Syk activation and Syk-induced activation of the NF-κB signaling pathway. Src activates MyD88 by phosphorylation at Y58 via the Src kinase domain. In addition, Ras-related C3 botulinum toxin substrate 1 (Rac1) activation and Rac1-induced formation of filamentous actin (F actin) activate Src in LPS-stimulated RAW264.7 cells.ConclusionsThese results suggest that the MyD88-Syk axis is a critical player in macrophage-mediated inflammatory responses, and its function is promoted by an upstream Src kinase activated by Rac1-generated filamentous actin (F-actin).

Stock Market Reactions during Different Phases of the COVID-19 Pandemic: Cases of Italy and Spain

The COVID-19 pandemic and pandemic-induced lockdowns and quarantine establishments have inevitably affected individuals, businesses, and governments. At the same time, the spread of the COVID-19 pandemic had a dramatic impact on financial markets all over the world and caused an increased level of uncertainty; the stock markets were no exception either. Most of the studies on the impact of the COVID-19 pandemic on stock markets are based either on the analysis of a relatively short period (the beginning of pandemic) or a longer period, which, in turn, is very heterogeneous in terms of both the information available on the COVID-19 virus and the measures taken to contain the virus and address the consequences of the pandemic. However, it is very important to assess the impact not only at the beginning of the pandemic but also in the subsequent periods and to compare the nature of this impact; the studies of this type are still fragmentary. Therefore, this research aims to investigate the impact of the COVID-19 pandemic on stock markets of two of the most severely affected European countries—Italy and Spain. To reach the aim of the research OLS regression models, heteroscedasticity-corrected models, GARCH (1,1) models, and VAR-based impulse response functions are employed. The results reveal that the stock market reaction to the spread of the COVID-19 pandemic differs depending on the country and period analyzed: OLS regression and heteroscedasticity-corrected models have not revealed the statistically significant impact of the spread of the COVID-19 pandemic, while impulse response functions demonstrated the non-zero primary response of analyzed markets to the COVID-19 shock, and GARCH models (in the case of Spain) confirmed that the COVID-19 pandemic increased the volatility of stock market return. This research contributes to the literature by providing a comprehensive impact assessment both during the whole pre-vaccination period of the pandemic and during different stages of this period.

Seismic Vulnerability of Primary Response Agencies in The Himalayan Province of Uttarakhand in India

Seismic vulnerability assessment of nearly 67%, 60%, and 18% of buildings of the first responders (Fire and Emergency Service, Police, and local administration, respectively) in the Himalayan province of Uttarakhand in India suggests 14.12% collapse, and 67.19% damage, and put to disuse immediately after an earthquake. This is to seriously limit emergency response capability of the state, and enhance sufferings and trauma of the affected community. US$ 95.27 is estimated as the cost of seismic safety of emergency response infrastructure, and this is to save building contents worth US$ 10.00 million. Prioritised demolition and reconstruction of Grade 5 buildings, detailed vulnerability assessment and phased retrofitting of Grade 4 and Grade 3 buildings, effective and strict compliance of building bye-laws, stringent punitive measures for lapses in lifeline buildings, mechanism for routine vulnerability assessment, and corrective maintenance are recommended for ensuring smooth and uninterrupted functioning of the emergency response agencies in the aftermath of an earthquake.

TLRs in COVID-19: How they drive immunopathology and the rationale for modulation

COVID-19 is both a viral illness and a disease of immunopathology. Proximal events within the innate immune system drive the balance between deleterious inflammation and viral clearance. We hypothesize that a divergence between the generation of excessive inflammation through over activation of the TLR associated myeloid differentiation primary response (MyD88) pathway relative to the TIR-domain-containing adaptor-inducing IFN-β (TRIF) pathway plays a key role in COVID-19 severity. Both viral elements and damage associated host molecules act as TLR ligands in this process. In this review, we detail the mechanism for this imbalance in COVID-19 based on available evidence, and we discuss how modulation of critical elements may be important in reducing severity of disease.

Innate Memory Reprogramming by Gold Nanoparticles Depends on the Microbial Agents That Induce Memory

Innate immune memory, the ability of innate cells to react in a more protective way to secondary challenges, is induced by exposure to infectious and other exogeous and endogenous agents. Engineered nanoparticles are particulate exogenous agents that, as such, could trigger an inflammatory reaction in monocytes and macrophages and could therefore be also able to induce innate memory. Here, we have evaluated the capacity of engineered gold nanoparticles (AuNPs) to induce a memory response or to modulate the memory responses induced by microbial agents. Microbial agents used were in soluble vs. particulate form (MDP and the gram-positive bacteria Staphylococcus aureus; β-glucan and the β-glucan-producing fungi C. albicans), and as whole microrganisms that were either killed (S. aureus, C. albicans) or viable (the gram-negative bacteria Helicobacter pylori). The memory response was assessed in vitro, by exposing human primary monocytes from 2-7 individual donors to microbial agents with or without AuNPs (primary response), then resting them for 6 days to allow return to baseline, and eventually challenging them with LPS (secondary memory response). Primary and memory responses were tested as production of the innate/inflammatory cytokine TNFα and other inflammatory and anti-inflammatory factors. While inactive on the response induced by soluble microbial stimuli (muramyl dipeptide -MDP-, β-glucan), AuNPs partially reduced the primary response induced by whole microorganisms. AuNPs were also unable to directly induce a memory response but could modulate stimulus-induced memory in a circumscribed fashion, limited to some agents and some cytokines. Thus, the MDP-induced tolerance in terms of TNFα production was further exacerbated by co-priming with AuNPs, resulting in a less inflammatory memory response. Conversely, the H. pylori-induced tolerance was downregulated by AuNPs only relative to the anti-inflammatory cytokine IL-10, which would lead to an overall more inflammatory memory response. These effects of AuNPs may depend on a differential interaction/association between the reactive particle surfaces and the microbial components and agents, which may lead to a change in the exposure profiles. As a general observation, however, the donor-to-donor variability in memory response profiles and reactivity to AuNPs was substantial, suggesting that innate memory depends on the individual history of exposures.

MyD88 in Hepatic Stellate Cells Promotes the Development of Alcoholic Fatty Liver via the AKT Pathway

Myeloid differentiation primary response gene 88 (MyD88), an adaptor protein in the TLRs signaling pathway, is expressed in various liver cells including hepatocytes, Kupffer cells and hepatic stellate cells (HSCs). However, the specific role of MyD88 in HSCs in alcoholic fatty liver (AFL) has not been well investigated. Here, to study the role of MyD88 in HSCs in the development of AFL and its related molecular mechanism, chronic-binge ethanol mice models were established in mice with specific MyD88 knockout in quiescent (MyD88GFAP−KO) and activated HSCs (MyD88SMA−KO), respectively. The results showed that the expression of MyD88 in HSCs was significantly increased in ethanol-induced liver tissues of wild-type mice. MyD88 deficiency in quiescent HSCs inhibited inflammation and lipogenesis, but in activated HSCs it only inhibited inflammation under the ethanol feeding condition. Further mechanism studies found that MyD88 promoted the osteopontin (OPN) secretion of HSCs, which further activated the AKT signaling pathway of hepatocytes and upregulated lipogenic gene expression to promote fat accumulation. In addition, OPN also promotes inflammation by activating p-STAT1. Thus, MyD88 may represent a potential candidate target for the prevention and targeted therapy in AFL, and MyD88 inhibitor can be also applied in inhibiting adipogenesis.

Adrenergic signaling controls early transcriptional programs during CD8+ T cell responses to viral infection

Viral infections drive the expansion and differentiation of responding CD8+ T cells into variegated populations of cytolytic effector and memory cells. While pro-inflammatory cytokines and cell surface immune receptors play a key role in guiding T cell responses to infection, T cells are also markedly influenced by neurotransmitters. Norepinephrine is a key sympathetic neurotransmitter, which acts to suppress CD8 + T cell cytokine secretion and lytic activity by signaling through the beta2-adrenergic receptor (ADRB2). Although ADRB2 signaling is considered generally immunosuppressive, its role in regulating differentiation of effector T cells in response to infection has not been investigated. Using an adoptive transfer approach, we compared the expansion and differentiation of wild type (WT) to Adrb2-/- CD8 + T cells throughout the primary response to vesicular stomatitis virus (VSV) infection in vivo. We measured the dynamic changes in transcriptome profiles of antigen-specific CD8 + T cells as they responded to VSV. Within the first 7 days of infection, WT cells out-paced the expansion of Adrb2-/- cells, which correlated with reduced expression of IL-2 and the IL-2Ralpha; in the absence of ADRB2. RNASeq analysis identified over 300 differentially expressed genes that were both temporally regulated following infection and selectively regulated in WT vs Adrb2-/- cells. These genes contributed to major transcriptional pathways including cytokine receptor activation, signaling in cancer, immune deficiency, and neurotransmitter pathways. By parsing genes within groups that were either induced or repressed over time in response to infection, we identified three main branches of genes that were differentially regulated by the ADRB2. These gene sets were predicted to be regulated by specific transcription factors involved in effector T cell development, such as Tbx21 and Eomes. Collectively, these data demonstrate a significant role for ADRB2 signaling in regulating key transcriptional pathways during CD8 + T cells responses to infection that may dramatically impact their functional capabilities and downstream memory cell development.