TLR4 signaling induces TLR3 up-regulation in alveolar macrophages during acute lung injury

Toll-Like Receptor 3 mRNA Expression of Peripheral Blood Mononuclear Cells Identifies Kidney Recipients with Potential for Improved Graft Performance

BACKGROUND Toll-like receptor 3 expression is detected both on the cell membrane and in endosomes of peripheral blood mononuclear cells (PBMC). Our goal in this study was to determine to what extent a single, baseline measurement of non-stimulated PBMC TLR3-mRNA can be related to baseline GFR (b-GFR) and post-follow-up-GFR (F-up-GFR) of a kidney transplant (KT) and baseline immunosuppression. MATERIAL AND METHODS In non-stimulated PBMC we investigated averaged mRNA expression of Toll-like receptor 3. A total of 133 patients were enrolled; the median of months after KT surgery was 11.4, with median F-up at 21.3 months. A favorable course (FCF) was determined if F-up-eGFR improved. An unfavorable course (UCF) was determined if F-up-eGFR was lower at the end of the observation. RESULTS The highest TLR3-mRNA expression was at b-GFR grade 3b; it was moderately higher at b-GFR grade 3a, and marginally higher at b-GFR grades 1+2. Most of the FCF group had b-GFR grade 3b, less frequent obesity, more effective immunosuppression, and much higher TLR3-mRNA (59% of cases were in the high-TLR3 area). Both delayed graft function (DGF) and TLR3-mRNA range below the median for the entire KT cohort (low-TLR3 area) had a negative association with b-GFR. The UCF group had more frequent DGFs and obesity, less effective immunosuppression, and lower TLR3-mRNA. CONCLUSIONS In patients with GFR grade 3, high levels of TLR3-mRNA are associated with improved graft efficacy. In patients with impaired graft function, low TLR3- mRNA expression reduces the likelihood of improved renal graft function.

Human placenta-derived mesenchymal stem cell administration protects against acute lung injury in a mouse model

This study aims to investigate the effect of placenta-derived mesenchymal stem cells (PMSCs) administration on tissue repair following acute lung injury (ALI). PMSCs were transplanted intravenously to a mouse model of lipopolysaccharide-induced ALI. The therapeutic effects were determined by evaluating several indicators, including pathology; the wet/dry ratio of the lungs; blood gas analysis; the total protein content, cell numbers, and the activity of myeloperoxidase (MPO) in bronchial alveolar lavage fluid (BALF); and the levels of anti-inflammatory and proinflammatory cytokines in serum and BALF. To investigate the underlying mechanism, PMSC-derived exosomes were used for ALI treatment. Administration of PMSCs improved the degree of lung injury, reduced inflammation, increased the expression levels of anti-inflammatory cytokines, and protected lung function. As expected, the effects of PMSC-derived exosomes in the ALI model were similar to those of PMSCs, both in terms of improved lung function and reduced inflammation. These findings suggest that PMSCs have ameliorating effects on ALI that are potentially mediated via their secreted exosomes.

Distinct trans-placental effects of maternal immune activation by TLR3 and TLR7 agonists: implications for schizophrenia risk

Exposure to infection in utero predisposes towards psychiatric diseases such as autism, depression and schizophrenia in later life. The mechanisms involved are typically studied by administering mimetics of double-stranded (ds) virus or bacterial infection to pregnant rats or mice. The effect of single-stranded (ss) virus mimetics has been largely ignored, despite evidence linking prenatal ss virus exposure with psychiatric disease. Understanding the effects of gestational ss virus exposure has become even more important with recent events. In this study, in pregnant mice, we compare directly the effects, on the maternal blood, placenta and the embryonic brain, of maternal administration of ds-virus mimetic poly I:C (to activate Toll-like receptor 3, TLR3) and ss-virus mimetic resiquimod (to activate TLR7/8). We find that, 4 h after the administration, both poly I:C and resiquimod elevated the levels of IL-6, TNFα, and chemokines including CCL2 and CCL5, in maternal plasma. Both agents also increased placental mRNA levels of IL-6 and IL-10, but only resiquimod increased placental TNFα mRNA. In foetal brain, poly I:C produced no detectable immune-response-related increases, whereas pronounced increases in cytokine (e.g. Il-6, Tnfα) and chemokine (e.g. Ccl2, Ccl5) expression were observed with maternal resiquimod administration. The data show substantial differences between the effect of maternal exposure to a TLR7/8 activator as compared to a TLR3 activator. There are significant implications for future modelling of diseases where maternal ss virus exposure contributes to environmental disease risk in offspring.

Ultramicronized Palmitoylethanolamide Inhibits NLRP3 Inflammasome Expression and Pro-Inflammatory Response Activated by SARS-CoV-2 Spike Protein in Cultured Murine Alveolar Macrophages

Despite its possible therapeutic potential against COVID-19, the exact mechanism(s) by which palmitoylethanolamide (PEA) exerts its beneficial activity is still unclear. PEA has demonstrated analgesic, anti-allergic, and anti-inflammatory activities. Most of the anti-inflammatory properties of PEA arise from its ability to antagonize nuclear factor-κB (NF-κB) signalling pathway via the selective activation of the PPARα receptors. Acting at this site, PEA can downstream several genes involved in the inflammatory response, including cytokines (TNF-α, Il-1β) and other signal mediators, such as inducible nitric oxide synthase (iNOS) and COX2. To shed light on this, we tested the anti-inflammatory and immunomodulatory activity of ultramicronized(um)-PEA, both alone and in the presence of specific peroxisome proliferator-activated receptor alpha (PPAR-α) antagonist MK886, in primary cultures of murine alveolar macrophages exposed to SARS-CoV-2 spike glycoprotein (SP). SP challenge caused a significant concentration-dependent increase in proinflammatory markers (TLR4, p-p38 MAPK, NF-κB) paralleled to a marked upregulation of inflammasome-dependent inflammatory pathways (NLRP3, Caspase-1) with IL-6, IL-1β, TNF-α over-release, compared to vehicle group. We also observed a significant concentration-dependent increase in angiotensin-converting enzyme-2 (ACE-2) following SP challenge. um-PEA concentration-dependently reduced all the analyzed proinflammatory markers fostering a parallel downregulation of ACE-2. Our data show for the first time that um-PEA, via PPAR-α, markedly inhibits the SP induced NLRP3 signalling pathway outlining a novel mechanism of action of this lipid against COVID-19.

Pattern recognition receptors as therapeutic targets for bacterial, viral and fungal sepsis

Sepsis remains to be a significant health care problem associated with high morbidities and mortalities. Recognizing its heterogeneity, it is critical to understand our host immunological responses to develop appropriate therapeutic approaches according to the type of sepsis. Because pattern recognition receptors are largely responsible for the recognition of microbes, we reviewed their role in immunological responses in the setting of bacterial, fungal and viral sepsis. We also considered their therapeutic potentials in sepsis.

Rhodobacter azotoformans LPS (RAP99-LPS) Is a TLR4 Agonist That Inhibits Lung Metastasis and Enhances TLR3-Mediated Chemokine Expression

The lipopolysaccharides (LPSs) of Rhodobacter are reported to be TLR4 antagonists. Accordingly, the extract of Rhodobacter azotoformans (RAP99) is used as a health supplement for humans and animals in Japan to regulate immune responses in vivo. We previously analyzed the LPS structure of RAP99 (RAP99-LPS) and found it is different from that of E. coli-LPS but similar to lipid A from Rhodobacter sphaeroides (RSLA), a known antagonist of TLR4, with both having three C14 fatty acyl groups, two C10 fatty acyl groups, and two phosphates. Here we show that RAP99-LPS has an immune stimulatory activity and acts as a TLR4 agonist. Pretreatment of RAP99-LPS suppressed E. coli-LPS-mediated weight loss, suggesting it is an antagonist against E. coli-LPS like other LPS isolated from Rhodobacter. However, injections of RAP99-LPS caused splenomegaly and increased immune cell numbers in C57BL/6 mice but not in C3H/HeJ mice, suggesting that RAP99-LPS stimulates immune cells via TLR4. Consistently, RAP99-LPS suppressed the lung metastasis of B16F1 tumor cells and enhanced the expression of TLR3-mediated chemokines. These results suggest that RAP99-LPS is a TLR4 agonist that enhances the activation status of the immune system to promote anti-viral and anti-tumor activity in vivo.

Biocompatible valproic acid-coupled nanoparticles attenuate lipopolysaccharide-induced inflammation

Inflammatory diseases like sepsis are associated with dysregulated gene expression, often caused by an imbalance of epigenetic regulators, such as histone acetyltransferases (HATs) and histone deacetylases (HDACs), and consequently, altered epigenetic chromatin signatures or aberrant posttranslational modifications of signalling proteins and transcription factors. Thus, HDAC inhibitors (HDACi) are a promising class of anti-inflammatory drugs. Recently, an efficient drug delivery system carrying the class I/IIa selective HDACi valproic acid (VPA) was developed to circumvent common disadvantages of free drug administration, e.g. short half-life and side effects. The cellulose-based sulphated VPA-coupled (CV-S) nanoparticles (NPs) are rapidly taken up by cells, do not cause any toxic effects and are fully biocompatible. Importantly, VPA is intracellularly cleaved from the NPs and HDACi activity could be proven. Here, we demonstrate that CV-S NPs exhibit overall anti-inflammatory effects in primary human macrophages and are able to attenuate the lipopolysaccharide-induced inflammatory response. CV-S NPs show superior potential to free VPA to suppress the TLR-MyD88-NF-κB signalling axis, leading to decreased TNF-α expression and secretion.

Roles of phosphatidyl inositol 3 kinase gamma (PI3Kγ) in respiratory diseases

Phosphatidyl inositol 3 kinase gamma (PI3Kγ) is expressed in all the cell types that are involved in airway inflammation and disease, including not only leukocytes, but also structural cells, where it is expressed at very low levels under physiological conditions, while is significantly upregulated after stress. In the airways, PI3Kγ behaves as a trigger or a controller, depending on the pathological context. In this review, the contribution of PI3Kγ in a plethora of respiratory diseases, spanning from acute lung injury, pulmonary fibrosis, asthma, cystic fibrosis and response to both bacterial and viral pathogens, will be commented.

WISP1 and TLR4 on Macrophages Contribute to Ventilator-Induced Lung Injury

Injurious mechanical ventilation has been shown to directly affect pulmonary and systemic immune responses. How these responses propagate or attenuate remains unknown. The goal of this study was to further determine whether toll-like receptor (TLR) 4 and WNT1-inducible signaling pathway protein 1 (WISP1) could contribute to injurious mechanical ventilation, especially focusing on the role of macrophages during experimental ventilator-induced lung injury. A prospective, randomized, and controlled animal study was designed, and male, wild-type (WT) C57BL/6 mice, TLR4 knockout (TLR4^-/-), and lyzTLR4 knockout (lyzTLR4^-/-) mice aging 8~12 weeks were used. Animals were anesthetized and randomized to spontaneous breathing (SB) group or to high tidal volume (VT, 20 ml/kg) mechanical ventilation (HTV) group. Histological evaluation, alveolar-capillary permeability of Evan's blue albumin (EBA), WISP1 protein levels, macrophage inflammatory protein-2 (MIP-2), and interleukin-6 (IL-6) in plasma and bronchoalveolar lavage fluid (BALF) concentrations were analyzed. HTV group was associated with a significant increase of WISP1 and EBA ratio in C57BL/6 mice, a significant decrease of WISP1 protein levels, and a significant decrease of IL-6, MIP-2 in plasma, and BALF concentrations of pro-inflammatory cytokines in TLR4^-/- and lyzTLR4^-/- knockout mice. In TLR4^-/- mice and lyzTLR4^-/- mice, there were also significant differences between SB group and HTV group in terms of H&E score and EBA ratio and level of pro-inflammation cytokines. The entire TLR4-targeted mice could further improve various inflammatory changes and damages when compared with lyzTLR4-targeted mice. What is more, TLR4^-/- mice and lyzTLR4^-/- mice reacted differently to rWISP1 and/or BMMC treated. TLR4^-/- mice had no response to rWISP1, while lyzTLR4^-/- mice still showed drastic response to both treatments. TLR4 and WISP1, especially the former one, on macrophages could contribute to releasing of pro-inflammatory cytokines during ventilator-induced lung injury. Injurious mechanical ventilation may result in an immune response which is similar to that of infection.

The Role of Innate Immunity in Pulmonary Infections

Innate immunity forms a protective line of defense in the early stages of pulmonary infection. The primary cellular players of the innate immunity against respiratory infections are alveolar macrophages (AMs), dendritic cells (DCs), neutrophils, natural killer (NK) cells, and innate lymphoid cells (ILCs). They recognize conserved structures of microorganisms through membrane-bound and intracellular receptors to initiate appropriate responses. In this review, we focus on the prominent roles of innate immune cells and summarize transmembrane and cytosolic pattern recognition receptor (PRR) signaling recognition mechanisms during pulmonary microbial infections. Understanding the mechanisms of PRR signal recognition during pulmonary pathogen infections will help us to understand pulmonary immunopathology and lay a foundation for the development of effective therapies to treat and/or prevent pulmonary infections.

miR-139-5p protects septic mice with acute lung injury by inhibiting Toll-like receptor 4/Myeloid differentiation factor 88/Nuclear factor-&mac_kgr;B signaling pathway

OBJECTIVES

To investigate the role of miR-139-5p and the TLR4/MyD88/NF-κB signaling pathway in acute lung injury in septic mice.

METHOD

A total of 140 healthy male SPF C57BL/6 mice were divided into seven groups, i.e., Normal, Control, NC, miR-139-5p mimic, miR-139-5p inhibitor, TAK-242, and miR-139-5p inhibitor+TAK-242 groups. The levels of miR-139-5p, proteins related to the TLR4/MyD88/NF-κB signaling pathway (TLR4, MyD88, and p-NF-κB p50), and MPO, SOD, GSH, and MDA in lung tissue were measured. The lung tissue wet-to-dry mass ratio (W/D), arterial oxygen partial pressure (PaO2), and carbon dioxide partial pressure (PaCO2) were measured.

RESULTS

A web-based bioinformatic tool predicted that MyD88 was a target of miR-139-5p, which was verified by a dual luciferase reporter assay. Compared with those in the Normal group, the levels of miR-139-5p, PaO2, SOD, and GSH were significantly lower, while those of TLR4, MyD88, p-NF-κB p50, W/D, PaCO2, IL-1β, TNF-α, IL-6, MPO, and MDA were higher in all other groups. Moreover, compared with their levels in the Control group, these indicators exhibited contrasting results in the miR-139-5p mimic and TAK-242 groups, but were similar in the miR-139-5p inhibitor group. In the miR-139-5p inhibitor+TAK-242 group, acute lung injury, aggravated by miR-139-5p inhibitor, was partially rescued by TAK-242.

CONCLUSION

miR-139-5p inhibits the TLR4/MyD88/NF-κB signaling pathway to alleviate acute lung injury in septic mice.

Transcription factor-mediated signaling pathways' contribution to the pathology of acute lung injury and acute respiratory distress syndrome

The 2019 novel coronavirus (2019-nCoV) is still spreading rapidly around the world, and one cause of lethality for patients infected with 2019-nCoV is acute respiratory distress syndrome (ARDS). ARDS is a severe syndrome of acute lung injury (ALI) that is predominantly triggered by inflammation and results in a sudden loss of, or damage to, kidney function. Emerging studies reveal that multiple transcription factor-associated signaling pathways are activated in the pathology of ALI/ARDS. Of these pathways, the activation of NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells), AP-1 (activator protein 1), IRFs (interferon regulatory factors), STATs (signal transducer and activator of transcription), Wnt/β-catenin-TCF/LEF (T-cell factor/lymphoid enhancer-binding factor), and CtBP2 (C-Terminal binding protein 2)-associated transcriptional complex contributes to ALI/ARDS pathology through diverse mechanisms, such as inducing proinflammatory cytokine levels and mediating macrophage polarization. In this review, we present an updated summary of the mechanisms underlying these signaling activations and regulations, as well as their contribution to the pathogenesis of ALI/ARDS. We aim to develop a better understanding of how ALI/ARDS occurs and improve ALI/ARDS therapy.

Mitigating Coronavirus Induced Dysfunctional Immunity for At-Risk Populations in COVID-19: Trained Immunity, BCG and "New Old Friends"

The novel, highly contagious coronavirus SARS-CoV-2 spreads rapidly throughout the world, leading to a deadly pandemic of a predominantly respiratory illness called COVID-19. Safe and effective anti-SARS-CoV-2 vaccines are urgently needed. However, emerging immunological observations show hallmarks of significant immunopathological characteristics and dysfunctional immune responses in patients with COVID-19. Combined with existing knowledge about immune responses to other closely related and highly pathogenic coronaviruses, this could forebode significant challenges for vaccine development, including the risk of vaccine failure. Animal data from earlier coronavirus vaccine efforts indicate that elderly people, most at risk from severe COVID-19 disease, could be especially at risk from immunopathologic responses to novel coronavirus vaccines. Bacterial "new old friends" such as Bacille Calmette-Guérin (BCG) or Mycobacterium obuense have the ability to elevate basal systemic levels of type 1 cytokines and immune cells, correlating with increased protection against diverse and unrelated infectious agents, called "trained immunity." Here we describe dysfunctional immune responses induced by coronaviruses, representing potentially difficult to overcome obstacles to safe, effective vaccine development for COVID-19, and outline how trained immunity could help protect high risk populations through immunomodulation with BCG and other "new old friends."

miR-143-3p impacts on pulmonary inflammatory factors and cell apoptosis in mice with mycoplasmal pneumonia by regulating TLR4/MyD88/NF-κB pathway

miR-143-3p is correlated with inflammatory pain responses, such as hsa-miR-143-3p expression reduction in fibromyalgia. The present study aimed to explore the effects of miR-143-3p and Toll-like receptor (TLR) 4/myeloid differentiation factor 88 (MyD88)/NF-κB signaling pathway on pulmonary inflammatory factors levels and alveolar epithelial cell apoptosis in mycoplasmal pneumonia mice. Twenty mice were selected as normal group. The 120 successfully modeled Mycoplasma pneumoniae (MP) infection mice were randomly divided into model group (without any treatment), negative control (NC) group (injected with NC mimic), miR-143-3p mimic group (injected with miR-143-3p mimic), miR-143-3p inhibitor group (injected with miR-143-3p inhibitor), TAK-242 group (treatment with TAK-242), and miR-143-3p inhibitor + TAK-242 group (treatment with miR-143-3p inhibitor + TAK-242). Compared with model group, model mice had up-regulated miR-143-3p expression and decreased MyD88 and p-NF-κB p50 protein expressions (all P<0.05); Model mice treated with miR-143-3p mimic and TAK-242 had reduced interleukin (IL)-2 and tumor necrosis factor (TNF)-α contents and protein expressions of MyD88, p-NF-κB p50, increased IL-10 content, fewer alveolar epithelial cell apoptosis, lower Bax expression and higher Bcl-2 expression (all P<0.05); however, mice with miR-143-3p inhibitor treatment showed opposite trends in terms of above indicators. The exacerbation of mycoplasmal pneumonia caused by miR-143-3p inhibitor was partly improved by miR-143-3p inhibitor + TAK-242 combination treatment (all P<0.05). Therefore, up-regulation of miR-143-3p expression may ameliorate pulmonary inflammatory factors levels and reduce alveolar epithelial cell apoptosis in mycoplasmal pneumonia mice by inhibiting TLR4/MyD88/NF-κB signaling pathway.

Chronic lung allograft dysfunction post-lung transplantation: The era of bronchiolitis obliterans syndrome and restrictive allograft syndrome

Chronic lung allograft dysfunction (CLAD) following lung transplantation limits long-term survival considerably. The main reason for this is a lack of knowledge regarding the pathological condition and the establishment of treatment. The consensus statement from the International Society for Heart and Lung Transplantation on CLAD in 2019 classified CLAD into two main phenotypes: Bronchiolitis obliterans syndrome and restrictive allograft syndrome. Along with this clear classification, further exploration of the mechanisms and the development of appropriate prevention and treatment strategies for each phenotype are desired. In this review, we summarize the new definition of CLAD and update and summarize the existing knowledge on the underlying mechanisms of bronchiolitis obliterans syndrome and restrictive allograft syndrome, which have been elucidated from clinicopathological observations and animal experiments worldwide.

Distinct expression patterns of TLR transcripts in human oocytes and granulosa cells from primordial and primary follicles

Ovulation has long been regarded as a process resembling an inflammatory response. Previously, luteinizing hormone (LH) was shown to induce Toll-like receptor 2 (TLR2) and TLR4 in granulosa cells from preovulatory hormone-dependent follicles. However, whether this could already initiate before the hormone-dependent phase is currently unknown. The aim of this study was to investigate TLR genes in human oocytes and granulosa cells from primordial and primary ovarian follicles during the hormone-independent phase. A class-comparison study of existing oocyte and granulosa cell RNA sequencing transcriptomes from primordial (n = 539 follicles) and primary (n = 261) follicles collected from three patients was examined. This revealed a distinct expression pattern of TLR3, TLR4 and TLR5 transcripts. Interestingly, the TLR3 protein was differentially detected in both the oocyte and the granulosa cells in primordial and primary follicles, suggesting that TLR3 is maternally contributed both as mRNA and protein. Intracellularly, the compartmentalized TLR3 dot-like staining in the intersection between the oocyte and the surrounding primordial granulosa cells. The TLR4 protein was detected in both primordial and primary follicles, with a notable staining in the granulosa cells. We functionally challenged ovaries in vitro, by polyinosinic:polycytidylic acid (poly I:C) and LPS, known to activate TLR3 and TLR4, respectively, and found a tendency for increased IL-6 production, which was particular evident in the LPS-treated group. Based on the expression of TLRs, it is notably that human primordial and primary follicles express genes that would allow them to respond to innate immune proteins and cytokines during follicle activation.

Flavonoids from Houttuynia cordata attenuate H1N1-induced acute lung injury in mice via inhibition of influenza virus and Toll-like receptor signalling

BACKGROUND

Influenza virus is one of the most important human pathogens, causing substantial seasonal and pandemic morbidity and mortality. Houttuynia cordata is a traditionally used medicinal plant for the treatment of pneumonia. Flavonoids are one of the major bioactive constituents of Houttuynia cordata.

PURPOSE

This study was designed to investigate the therapeutic effect and mechanism of flavonoid glycosides from H. cordata on influenza A virus (IAV)-induced acute lung injury (ALI) in mice.

METHODS

Flavonoids from H. cordata (HCF) were extracted from H. cordata and identified by high-performance liquid chromatography. Mice were infected intranasally with influenza virus H1N1 (A/FM/1/47). HCF (50, 100, or 200 mg/kg) or Ribavirin (100 mg/kg, the positive control) were administered intragastrically. Survival rates, life spans, weight losses, lung indexes, histological changes, inflammatory infiltration, and inflammatory markers in the lungs were measured. Lung virus titers and neuraminidase (NA) activities were detected. The expression of Toll-like receptors (TLRs) and levels of NF-κB p65 phosphorylation (NF-κB p65(p)) in the lungs were analysed. The effects of HCF on viral replication and TLR signalling were further evaluated in cells.

RESULTS

HCF contained 78.5% flavonoid glycosides. The contents of rutin, hyperin, isoquercitrin, and quercitrin in HCF were 8.8%, 26.7%, 9.9% and 31.7%. HCF (50, 100 and 200 mg/kg) increased the survival rate and life span of mice infected with the lethal H1N1 virus. In H1N1-induced ALI, mice treated with HCF (50, 100 and 200 mg/kg) showed lesser weight loss and lower lung index than the model group. The lungs of HCF-treated ALI mice presented more intact lung microstructural morphology, milder inflammatory infiltration, and lower levels of monocyte chemotactic protein 1 (MCP-1), interleukin-8 (IL-8), tumor necrosis factor-α (TNF-α) and malondialdehyde (MDA) than in the model group. Further investigation revealed that HCF exerted antiviral and TLR-inhibitory effects in vivo and in vitro. HCF (50, 100 and 200 mg/kg) reduced lung H1N1 virus titers and inhibited viral NA activity in mice. HCF (100 and 200 mg/kg) elevated the levels of interferon-β in lungs. HCF also decreased the expression of TLR3/4/7 and level of NF-κB p65(p) in lung tissues. In vitro experiments showed that HCF (50, 100 and 200 μg/ml) significantly inhibited viral proliferation and suppressed NA activity. In RAW 264.7 cells, TLR3, TLR4, and TLR7 agonist-stimulated cytokine secretion, NF-κB p65 phosphorylation, and nuclear translocation were constrained by HCF treatment. Furthermore, among the four major flavonoid glycosides in HCF, hyperin and quercitrin inhibited both viral replication and TLR signalling in cells.

CONCLUSION

HCF significantly alleviated H1N1-induced ALI in mice, which were associated with its dual antiviral and anti-inflammatory effects via inhibiting influenzal NA activity and TLR signalling. among the four major flavonoid glycosides in HCF, hyperin and quercitrin played key roles in the therapeutic effect of HCF.

PolyI:C Upregulated CCR5 and Promoted THP-1-Derived Macrophage Chemotaxis via TLR3/JMJD1A Signalling

Objective

This study aimed to evaluate the specific roles of polyinosinic:polycytidylic acid (polyI:C) in macrophage chemotaxis and reveal the potential regulatory mechanisms related to chemokine receptor 5 (CCR5).

Materials and Methods

In this experimental study, THP-1-derived macrophages (THP1-Mφs) induced from THP- 1 monocytes were treated with 25 μg/mL polyI:C. Toll-like receptor 3 (TLR3), Jumonji domain-containing protein (JMJD)1A, and JMJD1C small interfering RNA (siRNAs) were transfected into THP1-Mφs. Quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR) was used to detect the expression levels of TLR3, CCR5, 23 Jumonji C domain-containing histone demethylase family members, JMJD1A, and JMJD1C in THP1-Mφs with different siRNAs transfections. Western blot was performed to detect JMJD1A, JMJD1C, H3K9me2, and H3K9me3 expressions. A transwell migration assay was conducted to detect THP1-Mφ chemotaxis toward chemokine ligand 3 (CCL3). A chromatin immunoprecipitation (ChIP) assay was performed to detect H3K9me2-CCR5 complexes in THP1- Mφs.

Results

PolyI:C significantly upregulated CCR5 in THP1-Mφs and promoted chemotaxis toward CCL3 (P<0.05); these effects were significantly inhibited by TLR3 siRNA (P<0.01). JMJD1A and JMJD1C expression was significantly upregulated in polyI:C-stimulated THP1-Mφs, while only JMJD1A siRNA decreased CCR5 expression (P<0.05). JMJD1A siRNA significantly increased H3K9me2 expression in THP1-Mφs but not in polyI:C-stimulated THP1-Mφs. The ChIP result revealed that polyI:C significantly downregulated H3K9me2 in the promoter region of CCR5 in THP1- Mφs.

Conclusion

PolyI:C can enhance THP1-Mφ chemotaxis toward CCL3 regulated by TLR3/JMJD1A signalling and activate CCR5 expression by reducing H3K9me2 in the promoter region of CCR5.

The role of the innate immune system on pulmonary infections

Inhalation is required for respiration and life in all vertebrates. This process is not without risk, as it potentially exposes the host to environmental pathogens with every breath. This makes the upper respiratory tract one of the most common routes of infection and one of the leading causes of morbidity and mortality in the world. To combat this, the lung relies on the innate immune defenses. In contrast to the adaptive immune system, the innate immune system does not require sensitization, previous exposure or priming to attack foreign particles. In the lung, the innate immune response starts with the epithelial barrier and mucus production and is reinforced by phagocytic cells and T cells. These cells are vital for the production of cytokines, chemokines and anti-microbial peptides that are critical for clearance of infectious agents. In this review, we discuss all aspects of the innate immune response, with a special emphasis on ways to target aspects of the immune response to combat antibiotic resistant bacteria.

The role of protein SUMOylation in rheumatoid arthritis

Small ubiquitin-like modifier (SUMO) proteins, as a subgroup of post-translational modifiers, act to change the function of proteins. Through their interactions with different targets, immune pathways, and the responses they elicit, can be affected by these SUMO conjugations. Thus, both a change to protein function and involvement in immune pathways has the potential to promote an efficient immune response to either a pathogenic challenge, or the development of an imbalance that could lead to an autoimmune-based disease. Also, a variety of changes such as mutations and polymorphisms can interfere with common functions of these modifications and move an effective immune response in the direction of an autoimmune disease. The present review discusses the general characteristics of SUMO proteins and focuses on their involvement in rheumatoid arthritis as an autoimmune disease.

Influenza-induced immune suppression to methicillin-resistant Staphylococcus aureus is mediated by TLR9

Bacterial lung infections, particularly with methicillin-resistant Staphylococcus aureus (MRSA), increase mortality following influenza infection, but the mechanisms remain unclear. Here we show that expression of TLR9, a microbial DNA sensor, is increased in murine lung macrophages, dendritic cells, CD8⁺ T cells and epithelial cells post-influenza infection. TLR9^-/- mice did not show differences in handling influenza nor MRSA infection alone. However, TLR9^-/- mice have improved survival and bacterial clearance in the lung post-influenza and MRSA dual infection, with no difference in viral load during dual infection. We demonstrate that TLR9 is upregulated on macrophages even when they are not themselves infected, suggesting that TLR9 upregulation is related to soluble mediators. We rule out a role for elevations in interferon-γ (IFNγ) in mediating the beneficial MRSA clearance in TLR9^-/- mice. While macrophages from WT and TLR9^-/- mice show similar phagocytosis and bacterial killing to MRSA alone, following influenza infection, there is a marked upregulation of scavenger receptor A and MRSA phagocytosis as well as inducible nitric oxide synthase (Inos) and improved bacterial killing that is specific to TLR9-deficient cells. Bone marrow transplant chimera experiments and in vitro experiments using TLR9 antagonists suggest TLR9 expression on non-hematopoietic cells, rather than the macrophages themselves, is important for regulating myeloid cell function. Interestingly, improved bacterial clearance post-dual infection was restricted to MRSA, as there was no difference in the clearance of Streptococcus pneumoniae. Taken together these data show a surprising inhibitory role for TLR9 signaling in mediating clearance of MRSA that manifests following influenza infection.

Influenza-associated secondary bacterial infections, particularly with methicillin-resistant Staphylococcus aureus (MRSA), are a major cause of morbidity and mortality, and better therapeutic strategies are needed. Stimulation of TLR2 has shown promise for improving health in influenza-bacteria dual-infected animals. However, nothing is known about the role of other TLRs, including TLR9, in influenza-bacteria dual infection pathology. This is the first study of TLR9 regulation of influenza-bacterial superinfection and it highlights an unexpected pathologic role for TLR9 in regulating clearance of MRSA post-H1N1. It also highlights the important observation that TLR9 signaling has very different outcomes in the setting of influenza infection than in naïve mice and shows important distinctions in the mechanisms for susceptibility to MRSA vs. S. pneumoniae post-influenza. Our results also suggest that TLR9 expression on non-hematopoietic cells regulates macrophage function in vivo.

Mechanism of MCP-1 in Acute Lung Injury and Advanced Therapy by Drug-Loaded Dextrin Nanoparticle

Objective. To observe the expression of monocyte chemotactic protein 1 (MCP-1) in acute lung injury (ALI) rat model, to characterize its effect on the development and progression of ALI, and to identify the potential new drug delivery approach during in vivo experiment. Method. The effects of different doses of lipopolysaccharide (LPS) on human pulmonary artery endothelial cells (HPAEC) were tested. For the animal experiments, thirty Sprague-Dawley (SD) rats were divided into physiological saline control group (NC group), the LPS model group (L group), the antagonist RS102895 combined with LPS group (R + L group), and the antagonist RS102895-loaded polyaldehyde dextran nanoparticles combined with LPS group (DNPR + L group). The blood gas analysis and dry/wet weight ratio were detected 24 hours after interventions. The levels of inflammatory factors, tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), were tested by ELISA. The expression of monocyte chemoattractant protein-1 (MCP-1) in lung tissues was examined through Western blot, and the change of MCP-1 mRNA expression level was detected by performing RT-PCR. Result. LPS was responsible for inducing ALI in rats, and the degree of cell damage was dose-dependent. Blood gas analysis of L group showed that PaO2 and PaO2/FiO2 levels were significantly lower than those of the NC group (P<0.05), while the dry/wet weight ratio of lung tissues in L group increased (P<0.05). Inflammatory factors including TNF-α and IL-1β and the expression of MCP-1 in both protein and mRNA levels were higher in L group than in the NC group (P<0.05). The inhibition of the interaction between MCP-1 and chemokines receptor 2 (CCR2) by antagonist RS102895 can significantly alleviate the ALI in rats, which is accompanied by a significant decrease of inflammatory factors and MCP-1 expression (P<0.05). Compared with R + L group, treatment with DNPR and LPS combination significantly improved the condition of rats and decreased the level of TNF-α, IL-1β, and MCP-1 expression (P<0.05). Conclusion. In ALI, RS102895 can inhibit the MCP-1/CCR2 interaction, therefore, retarding the progress of ALI. Because of the high transfection efficiency of inhibitor RS102895packgaed by polyaldehyde dextran nanoparticles, this phenomenon particularly reached a significant level. The results imply new insights for the treatment of ALI.

Alveolar Macrophages Provide an Early Mycobacterium tuberculosis Niche and Initiate Dissemination

Mycobacterium tuberculosis (Mtb) infection is initiated in the distal airways, but the bacteria ultimately disseminate to the lung interstitium. Although various cell types, including alveolar macrophages (AM), neutrophils, and permissive monocytes, are known to be infected with Mtb, the initially infected cells as well as those that mediate dissemination from the alveoli to the lung interstitium are unknown. In this study, using a murine infection model, we reveal that early, productive Mtb infection occurs almost exclusively within airway-resident AM. Thereafter Mtb-infected, but not uninfected, AM localize to the lung interstitium through mechanisms requiring an intact Mtb ESX-1 secretion system. Relocalization of infected AM precedes Mtb uptake by recruited monocyte-derived macrophages and neutrophils. This dissemination process is driven by non-hematopoietic host MyD88/interleukin-1 receptor inflammasome signaling. Thus, interleukin-1-mediated crosstalk between Mtb-infected AM and non-hematopoietic cells promotes pulmonary Mtb infection by enabling infected cells to disseminate from the alveoli to the lung interstitium.

Activation of protein kinase C-α/heme oxygenase-1 signaling pathway improves mitochondrial dynamics in lipopolysaccharide-activated NR8383 cells

Mitochondrial function and morphology are dynamically regulated by fusion and fission. Heme oxygenase-1 (HO-1), which may be upregulated by protein kinase C-α (PKC-α), improves mitochondrial dynamics by controlling the balance between fusion and fission in vivo and in vitro. However, whether the PKC-α/HO-1 signaling pathway is one of the underlying mechanisms in adjusting mitochondrial dynamics in lipopolysaccharide (LPS)-activated macrophages has remained elusive. To explore this, NR8383 cells were pre-treated with PKC-α inhibitor Go6976 or PKC-α activator phorbol-12-myristate-13-acetate for 30 min and then stimulated with LPS for 24 h. Next, the expression of PKC-α, HO-1, mitofusin 1 (Mfn1) and mitofusin 2 (Mfn2), optic atrophy 1 (OPA1), dynamin-related protein 1 (Drp1) and fission 1 (Fis1) was detected to evaluate the possible implication of the PKC-α/HO-1 signaling pathway in the LPS-induced NR8383 cells. The results indicated that activation of the PKC-α/HO-1 signaling pathway increased superoxide dismutase activities and the respiratory control ratio (RCR), decreased the levels of malondialdehyde, reactive oxygen species (ROS), Drp1 and Fis1, and simultaneously enhanced the levels of Mfn1, Mfn2 and OPA1. In contrast, the PKC-α inhibitor decreased the expression of RCR, Mfn1, Mfn2 and OPA1, and increased the expression of MDA and ROS in NR8383 cells. The results suggest that activation of the PKC-α/HO-1 signaling pathway is necessary for the balance of mitochondrial dynamics and oxidative stress in macrophages, which provides clues for probing novel strategies against the detrimental effects of sepsis and other disease states.

Proteasome inhibition promotes autophagy and protects from endoplasmic reticulum stress in rat alveolar macrophages exposed to hypoxia-reoxygenation injury

Alveolar macrophages play vital roles in acute lung injury, and macrophage response to hypoxia play relevant roles to disease mechanisms. There is growing evidence that cell death pathways play crucial roles in physiological and pathological settings and that the ubiquitin-proteasome system is involved in the regulation of these processes. However, the functional role of proteasome in alveolar macrophages exposed to hypoxia-reoxygenation (H/R) injury is unknown. We aimed to investigate the function of proteasome on alveolar macrophages exposed to H/R and the underlying mechanisms. NR8383 cells were pretreated with proteasome activator sulforaphane (SFN) or inhibitor MG-132 for 1 hr, and then submitted to 2/6 hr, 4/6 hr, and 6/6 hr H/R treatment. Cell viability was assessed with MTT assay. Autophagy was monitored using electron transmission microscope and flow cytometry and western blotting. The endoplasmic reticulum (ER) stress and unfolded protein response (UPR) pathways were equally analyzed by western blotting. Cell apoptosis was detected by immunohistochemistry, caspase3/7 activity, and western blotting. The viability of NR8383 cells exposed to H/R was affected by proteasome activity and proteasome inhibition significantly inhibited cell death. Treatment with MG-132 led to autophagy activation and induced the survival of NR8383 cells exposed to H/R. Pretreatment with SFN significantly decreased cell autophagy and induced cell death. ER stress was activated in H/R-treated NR8383 cells, and SFN further promoted ER stress whereas proteasome inhibition led to contrary results. Proteasome inhibtion hindered cell apoptosis as demonstrated by decreased caspase-3/7 activity, immunolabelling, and western blot results. Proteasome inhibition might be a promising approach for treating H/R injury-related lung diseases.

Differential anti-inflammatory effects of budesonide and a p38 MAPK inhibitor AZD7624 on COPD pulmonary cells

Background

The effects of anti-inflammatory drugs in COPD patients may vary between different cell types. The aim of the current study was to assess the anti-inflammatory effects of the corticosteroid budesonide and a p38 MAPK inhibitor (AZD7624) on different cell types obtained from COPD patients and healthy controls.

Methods

Eight healthy smokers, 16 COPD infrequent exacerbators, and 16 frequent COPD exacerbators (≥2 exacerbations in the last year) were recruited for bronchoscopy and blood sampling. The anti-inflammatory effects of budesonide and AZD7624 were assessed on cytokine release from lipopolysaccharide-stimulated alveolar macrophages and peripheral blood mononuclear cells and polyinosinic:polycytidylic acid-stimulated bronchial epithelial cells.

Results

The anti-inflammatory effects of budesonide varied greatly within a patient according to the cell type studied. Bronchial epithelial cells showed the lowest sensitivity to budesonide, while peripheral blood mononuclear cells showed the greatest sensitivity. AZD7624 had a greater effect than budesonide on cytokine production from bronchial epithelial cells. Exacerbation frequency did not influence corticosteroid sensitivity.

Conclusion

We observed variable corticosteroid and p38 MAPK inhibitor anti-inflammatory responses within the same individual depending on the cell type studied. These findings support the use of multiple anti-inflammatory strategies in COPD patients due to differences between cell types.

Pathophysiology and classification of primary graft dysfunction after lung transplantation

The term primary graft dysfunction (PGD) incorporates a continuum of disease severity from moderate to severe acute lung injury (ALI) within 72 h of lung transplantation. It represents the most significant obstacle to achieving good early post-transplant outcomes, but is also associated with increased incidence of bronchiolitis obliterans syndrome (BOS) subsequently. PGD is characterised histologically by diffuse alveolar damage, but is graded on clinical grounds with a combination of PaO2/FiO2 (P/F) and the presence of radiographic infiltrates, with 0 being absence of disease and 3 being severe PGD. The aetiology is multifactorial but commonly results from severe ischaemia-reperfusion injury (IRI), with tissue-resident macrophages largely responsible for stimulating a secondary 'wave' of neutrophils and lymphocytes that produce severe and widespread tissue damage. Donor history, recipient health and operative factors may all potentially contribute to the likelihood of PGD development. Work that aims to minimise the incidence of PGD in ongoing, with techniques such as ex vivo perfusion of donor lungs showing promise both in research and in clinical studies. This review will summarise the current clinical status of PGD before going on to discuss its pathophysiology, current therapies available and future directions for clinical management of PGD.

Glycyrrhizin Ameliorate Ischemia Reperfusion Lung Injury through Downregulate TLR2 Signaling Cascade in Alveolar Macrophages

This experiment was conducted to study whether pretreatment with Glycyrrhizin (GL) could ameliorate ischemia-reperfusion (I/R) lung injury and investigate the mechanisms of its protective effects in a mice model. Six-eight weeks male BALB/C mice were randomly assigned to four groups (n = 6): Control, Glycyrrhizin, I/R and I/R+Glycyrrhizin. Lung I/R was achieved by clamping the left hilus pulmonis. GL (200 mg/kg) was injected intraperitoneally 30 min before anesthesia. Measurement of pathohistological lung injury score, pulmonary permeability, isolated alveolar macrophages, inflammatory mediators, TLR2 and its downstream factors (MyD88, NF-κB) were performed. The results were as anticipated. Pathohistological evaluation indicated that GL significantly ameliorated I/R-induced lung injury, pulmonary permeability and edema. Pretreatment with GL significantly inhibited I/R-induced inflammation in lung tissues and BALF. In addition, GL significantly decreased I/R-induced isolated alveolar macrophages and suppressed I/R-induced expression of TLR2 and its downstream factors in lung tissues and alveolar macrophages. Collectively, our data indicated that pretreatment with GL could ameliorate I/R lung injury. The mechanisms of its protective effects might be inhibit I/R-induced inflammatory response through downregulate TLR2 signaling cascade in alveolar macrophages.