The Immune Adaptor ADAP Regulates Reciprocal TGF-β1-Integrin Crosstalk to Protect from Influenza Virus Infection

Dampening of ISGylation of RIG-I by ADAP regulates type I interferon response of macrophages to RNA virus infection

While macrophage is one of the major type I interferon (IFN-I) producers in multiple tissues during viral infections, it also serves as an important target cell for many RNA viruses. However, the regulatory mechanism for the IFN-I response of macrophages to respond to a viral challenge is not fully understood. Here we report ADAP, an immune adaptor protein, is indispensable for the induction of the IFN-I response of macrophages to RNA virus infections via an inhibition of the conjugation of ubiquitin-like ISG15 (ISGylation) to RIG-I. Loss of ADAP increases RNA virus replication in macrophages, accompanied with a decrease in LPS-induced IFN-β and ISG15 mRNA expression and an impairment in the RNA virus-induced phosphorylation of IRF3 and TBK1. Moreover, using Adap-/- mice, we show ADAP deficiency strongly increases the susceptibility of macrophages to RNA-virus infection in vivo. Mechanically, ADAP selectively interacts and functionally cooperates with RIG-I but not MDA5 in the activation of IFN-β transcription. Loss of ADAP results in an enhancement of ISGylation of RIG-I, whereas overexpression of ADAP exhibits the opposite effect in vitro, indicating ADAP is detrimental to the RNA virus-induced ISGylation of RIG-I. Together, our data demonstrate a novel antagonistic activity of ADAP in the cell-intrinsic control of RIG-I ISGylation, which is indispensable for initiating and sustaining the IFN-I response of macrophages to RNA virus infections and replication.

Raymond E, Sakleshpur S, Steed AL. Aromatic amino acid metabolites alter interferon signaling and influenza pathogenesis

The ability of gut microbial metabolites to influence the host is increasingly recognized. The microbiota extensively metabolizes the three aromatic amino acids, tryptophan, tyrosine, and phenylalanine. Previously we have found that a metabolite of tyrosine, 4-OH-phenylpropionic acid, can enhance type I interferon (IFN) signaling and protect from influenza pathogenesis in a murine model. Herein we screened 17 related aromatic amino acid metabolites for effects on IFN signaling in human lung epithelial cells and monocytes alone and in the presence of IFN-β, influenza, and LPS. While the tryptophan family metabolites reduced IFN signaling in both cell types, the tyrosine and phenylalanine metabolites had varied effects, which were cell-type dependent. Pooled treatment of all these metabolites reduced IFN signaling in both cell types and suggested a tryptophan metabolite effect dominance. Strikingly, when all the metabolites were pooled together, we found reduced influenza recovery in both cell types. RNA sequencing further validated reduced viral loads and decreased IFN signaling. Single gene silencing of significantly upregulated genes identified by RNA sequencing (EGR2, ATP6VD02, SPOCK1, and IL31RA) did not completely abrogate the metabolite induced decrease in IFN signaling. However, these upregulated targets suggested a mechanistic link to TGF-beta signaling. Treatment with a TGF-beta inhibitor and combined targeted gene silencing led to a significant reversal of metabolite induced IFN signaling suppression. Finally, we demonstrated that intranasal administration of these metabolites prior to influenza infection led to reduced animal morbidity, viral titers, and inflammation. Our work implies that microbial metabolites can alter IFN signaling mechanistically through TGF-beta and promote beneficial outcomes during influenza infection.

A novel "prime and pull" strategy mediated by the combination of two dendritic cell-targeting designs induced protective lung tissue-resident memory T cells against H1N1 influenza virus challenge

Vaccination is still the most promising strategy for combating influenza virus pandemics. However, the highly variable characteristics of influenza virus make it difficult to develop antibody-based universal vaccines, until now. Lung tissue-resident memory T cells (TRM), which actively survey tissues for signs of infection and react rapidly to eliminate infected cells without the need for a systemic immune reaction, have recently drawn increasing attention towards the development of a universal influenza vaccine. We previously designed a sequential immunization strategy based on orally administered Salmonella vectored vaccine candidates. To further improve our vaccine design, in this study, we used two different dendritic cell (DC)-targeting strategies, including a single chain variable fragment (scFv) targeting the surface marker DC-CD11c and DC targeting peptide 3 (DCpep3). Oral immunization with Salmonella harboring plasmid pYL230 (S230), which displayed scFv-CD11c on the bacterial surface, induced dramatic production of spleen effector memory T cells (TEM). On the other hand, intranasal boost immunization using purified DCpep3-decorated 3M2e-ferritin nanoparticles in mice orally immunized twice with S230 (S230inDC) significantly stimulated the differentiation of lung CD11b+ DCs, increased intracellular IL-17 production in lung CD4+ T cells and elevated chemokine production in lung sections, such as CXCL13 and CXCL15, as determined by RNAseq and qRT‒PCR assays, resulting in significantly increased percentages of lung TRMs, which could provide efficient protection against influenza virus challenge. The dual DC targeting strategy, together with the sequential immunization approach described in this study, provides us with a novel "prime and pull" strategy for addressing the production of protective TRM cells in vaccine design.

Roles of TGF-β1 in Viral Infection during Pregnancy: Research Update and Perspectives

Transforming growth factor-beta 1 (TGF-β1) is a pleiotropic growth factor playing various roles in the human body including cell growth and development. More functions of TGF-β1 have been discovered, especially its roles in viral infection. TGF-β1 is abundant at the maternal-fetal interface during pregnancy and plays an important function in immune tolerance, an essential key factor for pregnancy success. It plays some critical roles in viral infection in pregnancy, such as its effects on the infection and replication of human cytomegalovirus in syncytiotrophoblasts. Interestingly, its role in the enhancement of Zika virus (ZIKV) infection and replication in first-trimester trophoblasts has recently been reported. The above up-to-date findings have opened one of the promising approaches to studying the mechanisms of viral infection during pregnancy with links to corresponding congenital syndromes. In this article, we review our current and recent advances in understanding the roles of TGF-β1 in viral infection. Our discussion focuses on viral infection during pregnancy, especially in the first trimester. We highlight the mutual roles of viral infection and TGF-β1 in specific contexts and possible functions of the Smad pathway in viral infection, with a special note on ZIKV infection. In addition, we discuss promising approaches to performing further studies on this topic.

Identification of Nifurtimox and Chrysin as Anti-Influenza Virus Agents by Clinical Transcriptome Signature Reversion

The rapid development in the field of transcriptomics provides remarkable biomedical insights for drug discovery. In this study, a transcriptome signature reversal approach was conducted to identify the agents against influenza A virus (IAV) infection through dissecting gene expression changes in response to disease or compounds’ perturbations. Two compounds, nifurtimox and chrysin, were identified by a modified Kolmogorov–Smirnov test statistic based on the transcriptional signatures from 81 IAV-infected patients and the gene expression profiles of 1309 compounds. Their activities were verified in vitro with half maximal effective concentrations (EC₅₀s) from 9.1 to 19.1 μM against H1N1 or H3N2. It also suggested that the two compounds interfered with multiple sessions in IAV infection by reversing the expression of 28 IAV informative genes. Through network-based analysis of the 28 reversed IAV informative genes, a strong synergistic effect of the two compounds was revealed, which was confirmed in vitro. By using the transcriptome signature reversion (TSR) on clinical datasets, this study provides an efficient scheme for the discovery of drugs targeting multiple host factors regarding clinical signs and symptoms, which may also confer an opportunity for decelerating drug-resistant variant emergence.

The multi-faceted roles of TGF-β in regulation of immunity to infection

Transforming Growth Factor-β is a potent regulator of the immune system, acting at every stage from thymic differentiation, population of the periphery, control of responsiveness, tissue repair and generation of memory. It is therefore a central player in the immune response to infectious pathogens, but its contribution is often clouded by multiple roles acting on different cells in time and space. Hence, context is all-important in understanding when TGF-β is beneficial or detrimental to the outcome of infection. In this review, a full range of infectious agents from viruses to helminth parasites are explored within this framework, drawing contrasts and general conclusions about the importance of TGF-β in these diseases.

Coronavirus infection: An immunologists' perspective

Coronavirus infections are frequent viral infections in several species. As soon as the severe acute respiratory syndrome (SARS) appeared in the early 2000s, most of the research focused on pulmonary disease. However, disorders in immune response and organ dysfunctions have been documented. Elderly individuals with comorbidities exhibit worse outcomes in all the coronavirus that cause SARS. Disease severity in SARS-CoV-2 infection is related to severe inflammation and tissue injury, and effective immune response against the virus is still under analysis. ACE2 receptor expression and polymorphism, age, gender and immune genetics are factors that also play an essential role in patients' clinical features and immune responses and have been partially discussed. The present report aims to review the physiopathology of SARS-CoV-2 infection and propose new research topics to understand the complex mechanisms of viral infection and viral clearance.

ADAP Y571 Phosphorylation Is Required to Prime STAT3 for Activation in TLR4-Stimulated Macrophages

Adhesion and degranulation-promoting adapter protein (ADAP), originally identified as an essential adaptor molecule in TCR signaling and T cell adhesion, has emerged as a critical regulator in innate immune cells such as macrophages; however, its role in macrophage polarization and inflammatory responses remains unknown. In this study, we show that ADAP plays an essential role in TLR4-mediated mouse macrophage polarization via modulation of STAT3 activity. Macrophages from ADAP-deficient mice exhibit enhanced M1 polarization, expression of proinflammatory cytokines and capacity in inducing Th1 responses, but decreased levels of anti-inflammatory cytokines in response to TLR4 activation by LPS. Furthermore, overexpression of ADAP enhances, whereas loss of ADAP reduces, the LPS-mediated phosphorylation and activity of STAT3, suggesting ADAP acts as a coactivator of STAT3 activity and function. Furthermore, the coactivator function of ADAP mostly depends on the tyrosine phosphorylation at Y571 in the motif YDSL induced by LPS. Mutation of Y571 to F severely impairs the stimulating effect of ADAP on STAT3 activity and the ability of ADAP to inhibit M1-like polarization in TLR4-activated mouse macrophages. Moreover, ADAP interacts with STAT3, and loss of ADAP renders mouse macrophages less sensitive to IL-6 stimulation for STAT3 phosphorylation. Collectively, our findings revealed an additional layer of regulation of TLR4-mediated mouse macrophage plasticity whereby ADAP phosphorylation on Y571 is required to prime STAT3 for activation in TLR4-stimulated mouse macrophages.

TGF-β1 signaling inhibit the in vitro apoptotic, infection and stimulatory cell response induced by influenza H1N1 virus infection on A549 cells

Influenza A virus (IAV) infection induces host cell responses that could derive in inflammatory and apoptotic response. In this respect, in multiple pathological situations, TGF-β1 has shown anti-inflammatory effect, but its role during IAV infection is poorly understood. Interestingly, recent profiling expression studies have suggested that the TGF-β1 pathway could be functionally related to the IAV infection's host response. To gain an understanding of the involvement of TGF-β1's signaling pathway during IAV infection, we compared different apoptotic proteins such as TNFR1, Fas ligand, XIAP, cIAP, among others proteins, and pro-inflammatory elements like IL-1β in the A549 cells during IAV infection (H1N1/NC/99), with and without 1 h of pre-treatment with TGF-β1. Pre-incubation with TGF-β1 significantly inhibited apoptosis and the presence of pro-apoptotic factors. Moreover, the relative abundance of immunodetected IAV M1 protein along 24 -h post-infection period was abridged, which correlated with a disminished infectious viral progeny Additionally, caspase 1 activation and increase of IL-1β induced by IAV infection was also reduced by TGF-β1 signaling activation. Whereas IAV infection increase of Smad-7 and, as consequence, partially inhibiting Smad2/3 phosphorylation, pre-treatment with TGF-β1 blocked IAV-dependent Smad7 induction and prevented Smad2/3 signaling shutdown. All these data suggest the role of TGF-β1 signaling pathway in the control of host cell response induced by the IAV infection and identify a potential clinical target to modulate acute cell death.

Analysis of genomics and immune infiltration patterns of epithelial-mesenchymal transition related to metastatic breast cancer to bone

OBJECTIVE

This study aimed to design a weighted co-expression network and a breast cancer (BC) prognosis evaluation system using a specific whole-genome expression profile combined with epithelial-mesenchymal transition (EMT)-related genes; thus, providing the basis and reference for assessing the prognosis risk of spreading of metastatic breast cancer (MBC) to the bone.

METHODS

Four gene expression datasets of a large number of samples from GEO were downloaded and combined with the dbEMT database to screen out EMT differentially expressed genes (DEGs). Using the GSE20685 dataset as a training set, we designed a weighted co-expression network for EMT DEGs, and the hub genes most relevant to metastasis were selected. We chose eight hub genes to build prognostic assessment models to estimate the 3-, 5-, and 10-year survival rates. We evaluated the models' independent predictive abilities using univariable and multivariable Cox regression analyses. Two GEO datasets related to bone metastases from BC were downloaded and used to perform differential genetic analysis. We used CIBERSORT to distinguish 22 immune cell types based on tumor transcripts.

RESULTS

Differential expression analysis showed a total of 304 DEGs, which were mainly related to proteoglycans in cancer, and the PI3K/Akt and the TGF-β signaling pathways, as well as mesenchyme development, focal adhesion, and cytokine binding functionally. The 50 hub genes were selected, and a survival-related linear risk assessment model consisting of eight genes (FERMT2, ITGA5, ITGB1, MCAM, CEMIP, HGF, TGFBR1, F2RL2) was constructed. The survival rate of patients in the high-risk group (HRG) was substantially lower than that of the low-risk group (LRG), and the 3-, 5-, and 10-year AUCs were 0.68, 0.687, and 0.672, respectively. In addition, we explored the DEGs of BC bone metastasis, and BMP2, BMPR2, and GREM1 were differentially expressed in both data sets. In GSE20685, memory B cells, resting memory T cell CD4 cells, T regulatory cells (T_regs), γδ T cells, monocytes, M0 macrophages, M2 macrophages, resting dendritic cells (DCs), resting mast cells, and neutrophils exhibited substantially different distribution between HRG and LRG. In GSE45255, there was a considerable difference in abundance of activated NK cells, monocytes, M0 macrophages, M2 macrophages, resting DCs, and neutrophils in HRG and LRG.

CONCLUSIONS

Based on the weighted co-expression network for breast-cancer-metastasis-related DEGs, we screened hub genes to explore a prognostic model and the immune infiltration patterns of MBC. The results of this study provided a factual basis to bioinformatically explore the molecular mechanisms of the spread of MBC to the bone and the possibility of predicting the survival of patients.

Surviving Deadly Lung Infections: Innate Host Tolerance Mechanisms in the Pulmonary System

Much research on infectious diseases focuses on clearing the pathogen through the use of antimicrobial drugs, the immune response, or a combination of both. Rapid clearance of pathogens allows for a quick return to a healthy state and increased survival. Pathogen-targeted approaches to combating infection have inherent limitations, including their pathogen-specific nature, the potential for antimicrobial resistance, and poor vaccine efficacy, among others. Another way to survive an infection is to tolerate the alterations to homeostasis that occur during a disease state through a process called host tolerance or resilience, which is independent from pathogen burden. Alterations in homeostasis during infection are numerous and include tissue damage, increased inflammation, metabolic changes, temperature changes, and changes in respiration. Given its importance and sensitivity, the lung is a good system for understanding host tolerance to infectious disease. Pneumonia is the leading cause of death for children under five worldwide. One reason for this is because when the pulmonary system is altered dramatically it greatly impacts the overall health and survival of a patient. Targeting host pathways involved in maintenance of pulmonary host tolerance during infection could provide an alternative therapeutic avenue that may be broadly applicable across a variety of pathologies. In this review, we will summarize recent findings on tolerance to host lung infection. We will focus on the involvement of innate immune responses in tolerance and how an initial viral lung infection may alter tolerance mechanisms in leukocytic, epithelial, and endothelial compartments to a subsequent bacterial infection. By understanding tolerance mechanisms in the lung we can better address treatment options for deadly pulmonary infections.

LRCH1 interferes with DOCK8-Cdc42-induced T cell migration and ameliorates experimental autoimmune encephalomyelitis

Xu et al. show that LRCH1 interferes with the GEF activity of DOCK8 to inhibit Cdc42 activation. Upon chemokine stimulation, DOCK8 is phosphorylated and released from LRCH1 to drive cell migration. LRCH1 overexpression reduces CD4⁺ T cell migration to the CNS and ameliorates experimental autoimmune encephalomyelitis.

Directional autoreactive CD4⁺ T cell migration into the central nervous system plays a critical role in multiple sclerosis. Recently, DOCK8 was identified as a guanine-nucleotide exchange factor (GEF) for Cdc42 activation and has been associated with human mental retardation. Little is known about whether DOCK8 is related to multiple sclerosis (MS) and how to restrict its GEF activity. Using two screening systems, we found that LRCH1 competes with Cdc42 for interaction with DOCK8 and restrains T cell migration. In response to chemokine stimulation, PKCα phosphorylates DOCK8 at its three serine sites, promoting DOCK8 separation from LRCH1 and translocation to the leading edge to guide T cell migration. Point mutations at the DOCK8 serine sites block chemokine- and PKCα-induced T cell migration. Importantly, Dock8 mutant mice or Lrch1 transgenic mice were protected from MOG (35–55) peptide–induced experimental autoimmune encephalomyelitis (EAE), whereas Lrch1-deficient mice displayed a more severe phenotype. Notably, DOCK8 expression was markedly increased in PBMCs from the acute phase of MS patients. Together, our study demonstrates LRCH1 as a novel effector to restrain PKCα–DOCK8–Cdc42 module–induced T cell migration and ameliorate EAE.

Adhesion- and Degranulation-Promoting Adapter Protein Promotes CD8 T Cell Differentiation and Resident Memory Formation and Function during an Acute Infection

During acute infections, naive Ag-specific CD8 T cells are activated and differentiate into effector T cells, most of which undergo contraction after pathogen clearance. A small population of CD8 T cells persists as memory to protect against future infections. We investigated the role of adhesion- and degranulation-promoting adapter protein (ADAP) in promoting CD8 T cell responses to a systemic infection. Naive Ag-specific CD8 T cells lacking ADAP exhibited a modest expansion defect early after Listeria monocytogenes or vesicular stomatitis virus infection but comparable cytolytic function at the peak of response. However, reduced numbers of ADAP-deficient CD8 T cells were present in the spleen after the peak of the response. ADAP deficiency resulted in a greater frequency of CD127(+) CD8 memory precursors in secondary lymphoid organs during the contraction phase. Reduced numbers of ADAP-deficient killer cell lectin-like receptor G1(-) CD8 resident memory T (TRM) cell precursors were present in a variety of nonlymphoid tissues at the peak of the immune response, and consequently the total numbers of ADAP-deficient TRM cells were reduced at memory time points. TRM cells that did form in the absence of ADAP were defective in effector molecule expression. ADAP-deficient TRM cells exhibited impaired effector function after Ag rechallenge, correlating with defects in their ability to form T cell-APC conjugates. However, ADAP-deficient TRM cells responded to TGF-β signals and recruited circulating memory CD8 T cells. Thus, ADAP regulates CD8 T cell differentiation events following acute pathogen challenge that are critical for the formation and selected functions of TRM cells in nonlymphoid tissues.

Serum biomarkers VEGF-C and IL-6 are associated with severe human Peripheral Artery Stenosis

BACKGROUND

Emerging reports propose possible biomarkers that are related to inflammation, nutrition and lipid parameters for detection of the progression of atherosclerotic plaques, peripheral artery disease (PAD) and particularly peripheral artery stenosis (PAS). However, it remains unclear which biomarkers in serum are associated with the severity of PAS.

FINDINGS

In this study, we measured serum levels of inflammatory biomarkers along with lipid and nutritional parameters in 53 patients who suffered different degrees of PAS. Serum concentrations of vascular endothelial growth factor-c (VEGF-C) and IL-6 (Interleukin 6) were significantly increased in patients showing moderate or severe PAS. Furthermore, the number of blood monocytes from PAS patients was significantly increased, which showed elevated adhesion to plate-coated fibrinogen. Compared to healthy subjects, freshly isolated or LPS (lipopolysaccharide)-stimulated blood monocytes from PAS patients could produce VEGF-C and IL-6 at higher levels.

CONCLUSIONS

Our study suggests that the increased number of blood monocytes might play key roles during the development of severe PAS, which enhance adhesion at the local narrowed peripheral artery and secret high levels of VEGF-C and IL-6. We suggest that serum concentrations of VEGF-C and IL-6 might be used as biomarkers for diagnosis severe PAS in combination with clinical imaging examination.

NSFC spurs significant basic research progress of respiratory medicine in China

Over the years, research in respiratory medicine has progressed rapidly in China. This commentary narrates the role of the National Natural Science Foundation of China (NSFC) in supporting the basic research of respiratory medicine, summarizes the major progress of respiratory medicine in China, and addresses the main future research directions sponsored by the NSFC.