IL-1β Impacts Vascular Integrity and Lymphatic Function in the Embryonic Omentum

Background: The chromatin remodeling enzyme Brahma Related Gene 1 (BRG1) regulates gene expression in a variety of rapidly differentiating cells during embryonic development. However, the critical genes that BRG1 regulates during lymphatic vascular development are unknown. Methods: We used genetic and imaging techniques to define the role of BRG1 in murine embryonic lymphatic development, although this approach inadvertently expanded our study to multiple interacting cell types. Results: We found that omental macrophages fine-tune an unexpected developmental process by which erythrocytes escaping from naturally discontinuous omental blood vessels are collected by nearby lymphatic vessels. Our data indicate that circulating fibrin(ogen) leaking from gaps in omental blood vessels can trigger inflammasome-mediated interleukin 1 beta (IL-1β) production and secretion from nearby macrophages. IL-1β destabilizes adherens junctions in omental blood and lymphatic vessels, contributing to both extravasation of erythrocytes and their uptake by lymphatics. BRG1 regulates IL-1β production in omental macrophages by transcriptionally suppressing the inflammasome trigger Receptor Interacting Protein Kinase 3 (RIPK3). Conclusions: Genetic deletion of Brg1 in embryonic macrophages leads to excessive IL-1β production, erythrocyte leakage from blood vessels, and blood-filled lymphatics in the developing omentum. Altogether, these results highlight a novel context for epigenetically-regulated crosstalk between macrophages, blood vessels, and lymphatics.

Serum sTREM-1 and CXCL-16 Levels in Children with Mycoplasma pneumoniae Pneumonia and Their Diagnostic Value

Mycoplasma pneumoniae pneumonia (MPP) is an acute respiratory tract infection caused by Mycoplasma pneumoniae. It is characterized by severe symptoms, long course of disease, many intrapulmonary complications, and poor therapeutic effect. In recent years, the incidence of Mycoplasma infection have been gradually rising trend, and the children’s own immune system development is not mature, cases differences, children with mild can only show the upper respiratory tract infection, and critically ill children can lead to lung infection and even lead to multiple organ dysfunction, affect life and health of children. Soluble triggering receptors expressed on myeloid cell-1 (sTREM-1) is a subtype secreted by myeloid cell trigger receptor-1, which is released into blood in large amounts when the body is infected, and is a newly discovered inflammatory indicator in recent years. CXC chemokine 16 (CXCL-16) can recruit lymphocytes by chemotaxis through binding to its receptor CXCR6 to participate in the body’s immune regulation. The purpose of this study was to investigate serum sTREM-1 and CXCL-16 levels in children with MPP and to analyze their correlation with the disease and diagnostic value. The results showed that the serum levels of sTREM-1 and CXCL-16 were increased in children with Mycoplasma. Serum levels of sTREM-1 and CXCL-16 were positively correlated with the severity of the disease. sTREM-1 combined with CXCL-16 has an important value in the diagnosis of children with MPP.

FGF1 Fusions with the Fc Fragment of IgG1 for the Assembly of GFPpolygons-Mediated Multivalent Complexes Recognizing FGFRs

FGFRs are cell surface receptors that, when activated by specific FGFs ligands, transmit signals through the plasma membrane, regulating key cellular processes such as differentiation, division, motility, metabolism and death. We have recently shown that the modulation of the spatial distribution of FGFR1 at the cell surface constitutes an additional mechanism for fine-tuning cellular signaling. Depending on the multivalent, engineered ligand used, the clustering of FGFR1 into diverse supramolecular complexes enhances the efficiency and modifies the mechanism of receptor endocytosis, alters FGFR1 lifetime and modifies receptor signaling, ultimately determining cell fate. Here, we present a novel approach to generate multivalent FGFR1 ligands. We functionalized FGF1 for controlled oligomerization by developing N- and C-terminal fusions of FGF1 with the Fc fragment of human IgG1 (FGF1-Fc and Fc-FGF1). As oligomerization scaffolds, we employed GFPpolygons, engineered GFP variants capable of well-ordered multivalent display, fused to protein G to ensure binding of Fc fragment. The presented strategy allows efficient assembly of oligomeric FGFR1 ligands with up to twelve receptor binding sites. We show that multivalent FGFR1 ligands are biologically active and trigger receptor clustering on the cell surface. Importantly, the approach described in this study can be easily adapted to oligomerize alternative growth factors to control the activity of other cell surface receptors.

Anti-Fn14 Antibody-Conjugated Nanoparticles Display Membrane TWEAK-Like Agonism

Conventional bivalent IgG antibodies targeting a subgroup of receptors of the TNF superfamily (TNFSF) including fibroblast growth factor-inducible 14 (anti-Fn14) typically display no or only very limited agonistic activity on their own and can only trigger receptor signaling by crosslinking or when bound to Fcγ receptors (FcγR). Both result in proximity of multiple antibody-bound TNFRSF receptor (TNFR) molecules, which enables engagement of TNFR-associated signaling pathways. Here, we have linked anti-Fn14 antibodies to gold nanoparticles to mimic the “activating” effect of plasma membrane-presented FcγR-anchored anti-Fn14 antibodies. We functionalized gold nanoparticles with poly-ethylene glycol (PEG) linkers and then coupled antibodies to the PEG surface of the nanoparticles. We found that Fn14 binding of the anti-Fn14 antibodies PDL192 and 5B6 is preserved upon attachment to the nanoparticles. More importantly, the gold nanoparticle-presented anti-Fn14 antibody molecules displayed strong agonistic activity. Our results suggest that conjugation of monoclonal anti-TNFR antibodies to gold nanoparticles can be exploited to uncover their latent agonism, e.g., for immunotherapeutic applications.

Impairment of SARS-CoV-2 spike glycoprotein maturation and fusion activity by the broad-spectrum anti-infective drug nitazoxanide

ABSTRACTThe emergence of the highly-pathogenic severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative agent of COVID-19 (coronavirus disease-2019), has caused an unprecedented global health crisis, as well as societal and economic disruption. The SARS-CoV-2 spike (S), a surface-anchored trimeric class-I fusion glycoprotein essential for entry into host cells, represents a key target for developing vaccines and therapeutics capable of blocking virus invasion. The emergence of several SARS-CoV-2 spike variants that facilitate virus spread and may affect the efficacy of recently developed vaccines, creates great concern and highlights the importance of identifying antiviral drugs to reduce SARS-CoV-2-related morbidity and mortality. Nitazoxanide, a thiazolide originally developed as an antiprotozoal agent with recognized broad-spectrum antiviral activity in-vitro and in clinical studies, was recently shown to be effective against several coronaviruses, including SARS-CoV-2. Using biochemical and pseudovirus entry assays, we now demonstrate that nitazoxanide interferes with the SARS-CoV-2 spike biogenesis, hampering its maturation at an endoglycosidase H-sensitive stage, and hindering its fusion activity in human cells. Besides membrane fusion during virus entry, SARS-CoV-2 S-proteins in infected cells can also trigger receptor-dependent formation of syncytia, observed in-vitro and in COVID-19 patients tissues, facilitating viral dissemination between cells and possibly promoting immune evasion. Utilizing two different quantitative cell-cell fusion assays, we show that nitazoxanide is effective in inhibiting syncytia formation mediated by different SARS-CoV-2 spike variants in human lung, liver and intestinal cells. The results suggest that nitazoxanide may represent a useful tool in the fight against COVID-19 infections, inhibiting SARS-CoV-2 replication and preventing spike-mediated syncytia formation.

TLR4: the fall guy in sepsis?

Sepsis and its impact on human health can be traced back to 1000 BC and continues to be a major health burden today. It causes about 11 million deaths world-wide of which, more than a third are due to neonatal sepsis. There is no effective treatment other than fluid resuscitation therapy and antibiotic treatment that leave patients immunosuppressed and vulnerable to nosocomial infections. Added to that, ageing population and the emergence of antibiotic resistant bacteria pose new challenges. Most of the deleterious effects of sepsis are due to the host response to the systemic infection. In the initial phase of infection, hyper activation of the immune system leads to cytokine storm, which could lead to organ failure and this accounts for about 15% of overall deaths. However, the subsequent immune paralysis phase (mostly attributed to apoptotic death of immune cells) accounts for about 85% of all deaths. Past clinical trials (more than 100 in the last 30 years) all targeted the inflammatory phase with little success, predictably, for inflammation is a necessary process to fight infection. In order to identify the regulators of immune cell death during sepsis, we carried out an unbiased, whole genome CRISPR screening in mice and identified Trigger Receptor Expressed in Myeloid-like 4 (Treml4) as the receptor that controls both the inflammatory phase and the immune suppression phase in sepsis (Nedeva et al. (2020) Nature Immunol, doi: 10.1038/s41590-020-0789-z). Characterising the Treml4 gene knockout mice revealed new insights into the relative roles of TLR4 and TREML4 in inducing the inflammatory cytokine storm during sepsis.

GDNF synthesis, signaling, and retrograde transport in motor neurons

Glial cell line–derived neurotrophic factor (GDNF) is a 134 amino acid protein belonging in the GDNF family ligands (GFLs). GDNF was originally isolated from rat glial cell lines and identified as a neurotrophic factor with the ability to promote dopamine uptake within midbrain dopaminergic neurons. Since its discovery, the potential neuroprotective effects of GDNF have been researched extensively, and the effect of GDNF on motor neurons will be discussed herein. Similar to other members of the TGF-β superfamily, GDNF is first synthesized as a precursor protein (pro-GDNF). After a series of protein cleavage and processing, the 211 amino acid pro-GDNF is finally converted into the active and mature form of GDNF. GDNF has the ability to trigger receptor tyrosine kinase RET phosphorylation, whose downstream effects have been found to promote neuronal health and survival. The binding of GDNF to its receptors triggers several intracellular signaling pathways which play roles in promoting the development, survival, and maintenance of neuron-neuron and neuron-target tissue interactions. The synthesis and regulation of GDNF have been shown to be altered in many diseases, aging, exercise, and addiction. The neuroprotective effects of GDNF may be used to develop treatments and therapies to ameliorate neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS). In this review, we provide a detailed discussion of the general roles of GDNF and its production, delivery, secretion, and neuroprotective effects on motor neurons within the mammalian neuromuscular system.

Central nervous system damage markers in children: current state of the problem

Pathology of the central nervous system (CNS) occupies one of the leading places in the structure of childhood morbidity and mortality. In the modern world the diagnosis of central nervous system diseases is based not only on the a thorough history, identification of certain neurological symptoms during an objective medical examination of the child and data from various neuroimaging methods, but also on the use of laboratory research methods with the identification of specific markers which indicate a pathological process occurring in the tissues of the brain and spinal cord. The article presents modern data on the biochemical parameters indicating damage to the nervous tissue, as well as their role in conditions of homeostasis and the prospects for further research. We analyzed the latest domestic and foreign literature on the properties and role of such indicators as neurotrophic growth factor, vascular endothelial growth factor, monocytic chemotactic protein, trigger receptor expressed on myeloid cells-1, trigger receptor expressed on myeloid cells-2, transforming growth factor, fractalkin, a nerve growth factor, which is a promising direction in the study of damage to nerve tissue. We can conclude that а study of the level of these markers will help diagnose the presence of damage to the nerve tissue, its severity, and therefore, select the right individual therapy for each specific child, thereby preventing the development of severe neurological consequences.