Influence of lipopolysaccharide-binding protein on pulmonary inflammation in gram-negative pneumonia

Immunologic role of macrophages in sepsis-induced acute liver injury

Sepsis-induced acute liver injury (SALI), a manifestation of sepsis multi-organ dysfunction syndrome, is associated with poor prognosis and high mortality. The diversity and plasticity of liver macrophage subpopulations explain their different functional responses in different liver diseases. Kupffer macrophages, liver capsular macrophages, and monocyte-derived macrophages are involved in pathogen recognition and clearance and in the regulation of inflammatory responses, exacerbating the progression of SALI through different pathways of pyroptosis, ferroptosis, and autophagy. Concurrently, they play an important role in maintaining hepatic homeostasis and in the injury and repair processes of SALI. Other macrophages are recruited to diseased tissues under pathological conditions and are polarized into various phenotypes (mainly M1 and M2 types) under the influence of signaling molecules, transcription factors, and metabolic reprogramming, thereby exerting different roles and functions. This review provides an overview of the immune role of macrophages in SALI and discusses the multiple roles of macrophages in liver injury and repair to provide a reference for future studies.

The Potential of Probiotics as Ingestible Adjuvants and Immune Modulators for Antiviral Immunity and Management of SARS-CoV-2 Infection and COVID-19

Probiotic bacteria are able to modulate general antiviral responsiveness, including barrier functionality and innate and adaptive immune responses. The COVID-19 pandemic, resulting from SARS-CoV-2 infection, has created a need to control and treat this viral infection and its ensuing immunopathology with a variety of approaches; one such approach may involve the administration of probiotic bacteria. As with most viral infections, its pathological responses are not fully driven by the virus, but are significantly contributed to by the host's immune response to viral infection. The potential adoption of probiotics in the treatment of COVID-19 will have to appreciate the fine line between inducing antiviral immunity without over-provoking immune inflammatory responses resulting in host-derived immunopathological tissue damage. Additionally, the effect exerted on the immune system by SARS-CoV-2 evasion strategies will also have to be considered when developing a robust response to this virus. This review will introduce the immunopathology of COVID-19 and the immunomodulatory effects of probiotic strains, and through their effects on a range of respiratory pathogens (IAV, SARS-CoV, RSV), as well as SARS-CoV-2, will culminate in a focus on how these bacteria can potentially manipulate both infectivity and immune responsiveness via barrier functionality and both innate and adaptive immunity. In conclusion, the harnessing of induction and augmentation of antiviral immunity via probiotics may not only act as an ingestible adjuvant, boosting immune responsiveness to SARS-CoV-2 infection at the level of barrier integrity and innate and adaptive immunity, but also act prophylactically to prevent infection and enhance protection afforded by current vaccine regimens.

Plasma levels of C-reactive protein, matrix metalloproteinase-7 and lipopolysaccharide-binding protein distinguish active pulmonary or extrapulmonary tuberculosis from uninfected controls in children

The immune profile associated with distinct clinical forms of tuberculosis (TB) has been extensively described for adult populations. Nevertheless, studies describing immune determinants of pulmonary or extrapulmonary TB (PTB or EPTB, respectively) in children are scarce. Here, we retrospectively assessed plasma levels of several mediators of inflammation in age and sex-matched children from South India presenting with PTB (n = 14) or EPTB (n = 22) as well as uninfected healthy controls (n = 19) to identify biomarkers that could accurately distinguish different TB clinical forms. Furthermore, we performed exploratory analyses testing the influence of sex on the systemic inflammatory profile. The analyses identified a biosignature of 10 biomarkers capable of distinguishing the three clinical groups simultaneously. Machine-learning decision trees indicated that C-reactive protein (CRP), matrix metalloproteinase (MMP)-7 and lipopolysaccharide-binding protein (LBP) were the markers that, when combined, displayed the highest accuracy in identifying the clinical groups. Additional exploratory analyses suggested that the disease signatures were highly influenced by sex. Therefore, sex differentially impacted status of systemic inflammation, immune activation and tissue remodeling in children with distinct clinical forms of TB. Regardless of such nuances related to biological sex, MMP-7, CRP and LBP were strong discriminators of active TB and thus could be considered as biomarkers useful in discrimination different TB clinical forms. These observations have implications on our understanding of the immunopathology of both clinical forms of TB in pediatric patients. If validated by other studies in the future, the combination of identified biomarkers may help development of point-of-care diagnostic or prognostic tools.

Lipopolysaccharide-Binding Protein Is an Early Biomarker of Cardiac Function After Radiation Therapy for Breast Cancer

PURPOSE

To evaluate the prognostic potential of lipopolysaccharide-binding protein (LBP) levels after breast cancer radiation therapy (RT) for incipient cardiac dysfunction.

METHODS AND MATERIALS

In this single-centered study, we prospectively enrolled female patients treated for left breast cancer. Healthy age- and sex-matched participants were recruited as controls. LBP levels, cardiac troponin T, N-terminal propeptide of the brain natriuretic peptide, fatty acid binding protein, and C-reactive protein were assessed at three timepoints-before RT, after the last RT fraction, and 1 month after the last fraction. Echocardiographic evaluation was done 3 to 3.75 years after RT.

RESULTS

We recruited 51 patients and 78 controls. Baseline LBP concentrations in the study group were significantly higher than in controls at baseline (P < .001), at 24 hours, and at 1 month after RT (P = .003 and P < .001, respectively). Other biomarkers (cardiac troponin T, N-terminal propeptide of the brain natriuretic peptide, fatty acid binding protein, and C-reactive protein) did not differ in any of the timepoints. Posttreatment LBP concentrations were significantly and positively correlated with heart- and lung-associated dose-volume histogram variables. Posttreatment and follow-up LBP levels correlated positively with the E/E' echocardiographic index reflective of the diastolic function. After adjustment for left anterior descending artery mean dose, left ventricle mean dose, mean heart dose, and type of surgery, LBP remained significantly correlated with E/E' when measured 24 hours after RT (beta = 0.41, P = .032) and 1 month after RT (beta = 0.43, P = .028).

CONCLUSIONS

Serum LBP concentrations correlate with diastolic function evaluated 3 years after the completion of RT, making LBP a potentially useful prognostic parameter.

The novel N-methyl-d-aspartate receptor antagonist MN-08 ameliorates lipopolysaccharide-induced acute lung injury in mice

Acute lung injury (ALI) is a clinically severe respiratory disorder, and effective therapy is urgently needed. MN-08, a novel synthetic N-methyl-d-aspartate receptor (NMDAR) antagonist, was investigated for its effect on lipopolysaccharide (LPS)-induced ALI. In vitro, the protective effect of MN-08 on inflammatory response, oxidative stress, and tight junctions (TJs) structure was explored in LPS-induced RAW 264.7 cells and A549 cells. MN-08 markedly decreased (p < 0.001) the levels of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and reactive oxygen species (ROS), whereas it moderately upregulated (p < 0.05) heme oxygenase (HO)-1 protein expression in LPS-induced RAW 264.7 cells. Moreover, MN-08 significantly inhibited (p < 0.001) cell apoptosis and improved (p < 0.001) protein expression of TJs in LPS-induced A549 cells. In vivo, the therapeutic effect of MN-08 was evaluated in the LPS-induced ALI model through intratracheal instillation in BALB/c mice. MN-08 administration dramatically attenuated (p < 0.001) pulmonary pathological changes and reduced (p < 0.001) the levels of glutamate, myeloperoxidase (MPO), malondialdehyde (MDA), and number of cells in BALF, whereas it increased (p < 0.05) superoxide dismutase (SOD) and glutathione (GSH) activities in ALI mice. Furthermore, MN-08 markedly blocked the mitogen-activated protein kinases (MAPKs)/nuclear translocation of nuclear factor-κB (NF-κB) signaling pathways in RAW 264.7 cells and lung tissues. These results indicate that MN-08 exhibits lung protection in an LPS-induced ALI model via anti-inflammatory and anti-oxidative activities.

Modulation of Innate Immunity by G-CSF and Inflammatory Response by LBPK95A Improves the Outcome of Sepsis in a Rat Model

Introduction

Sepsis is the primary cause of death from infection. We wanted to improve the outcome of sepsis by stimulating innate immunity in combination with modulating the severity of inflammatory responses in rats.

Method

Sepsis was induced by the injection of feces suspension (control). A 5-day course of G-CSF treatment was given before the septic insult (G-CSF). The inflammatory response was decreased using various doses of the LPS-blocking peptide LBPK95A (5 mg/kg = 100% Combi group, 0.5 mg/kg = 10% Combi group, and 0.05 mg/kg = 1% Combi group). Survival rates were observed. Bacterial clearance, neutrophil infiltration, tissue damage, and the induction of hepatic and systemic inflammatory responses were determined 2 h and 12 h after the septic insult.

Results

High-dose LBPK95A (100% Combi) reduced the survival rate to 10%, whereas low-dose LBPK95A (10% and 1% Combi) increased the survival rates to 50% and 80%, respectively. The survival rates inversely correlated with multiorgan damage as indicated by the serum levels of ALT and urea. G-CSF treatment increased the white blood cell counts, hepatic neutrophil infiltration, and bacterial clearance in the liver, lung, and blood. The blockade of the LPS-LBP interaction decreased neutrophil infiltration, led to increased white blood cell count, and decreased hepatic neutrophil infiltration, irrespective of dose. However, bacterial clearance improved in the 1% and 10% Combi groups but worsened in the 100% Combi group. G-CSF increased TNF-α and IL-6 levels. Irrespective of dose, the blockade of the LPS-LBP interaction was associated with low systemic cytokine levels and delayed increases in hepatic TNF-α and IL-6 mRNA expression. The delayed increase in cytokines was associated with the phosphorylation of STAT3 and AKT.

Conclusion

Our results revealed that increasing innate immunity by G-CSF pretreatment and decreasing inflammatory responses using LBPK95A improved the survival rates in a rat sepsis model and could be a novel strategy to treat sepsis.

Electroporation-mediated delivery of FER gene enhances innate immune response and improves survival in a murine model of pneumonia

Previously, we reported that electroporation-mediated (EP) delivery of the FER gene improved survival in a combined trauma-pneumonia model. The mechanism of this protective effect is unknown. In this paper, we performed a pneumonia model in C57/BL6 mice with 500 CFU of Klebsiella pneumoniae. After inoculation, a plasmid encoding human FER was delivered by EP into the lung (PNA/pFER-EP). Survival of FER-treated vs. controls (PNA; PNA/EP-pcDNA) was recorded. In parallel cohorts, bronchial alveolar lavage (BAL) and lung were harvested at 24 and 72 h with markers of infection measured. FER-EP-treated animals reduced bacterial counts and had better 5-day survival compared to controls (80 vs. 20 vs. 25%; p < 0.05). Pre-treatment resulted in 100% survival. With FER, inflammatory monocytes were quickly recruited into BAL. These cells had increased surface expression for Toll-receptor 2 and 4, and increased phagocytic and myeloperoxidase activity at 24 h. Samples from FER electroporated animals had increased phosphorylation of STAT transcription factors, varied gene expression of IL1β, TNFα, Nrf2, Nlrp3, Cxcl2, HSP90 and increased cytokine production of TNF-α, CCL-2, KC, IFN-γ, and IL-1RA. In a follow-up experiment, using Methicillin-resistant Staphylococcus aureus (MRSA) similar bacterial reduction effects were obtained with FER gene delivery. We conclude that FER overexpression improves survival through STAT activation enhancing innate immunity and accelerating bacterial clearance in the lung. This constitutes a novel mechanism of inflammatory regulation with therapeutic potential in the setting of hospital-acquired pneumonia.

Lipopolysaccharide-Binding Protein Downregulates Fractalkine through Activation of p38 MAPK and NF-κB

Background

LBP and fractalkine are known to be involved in the pathogenesis of ARDS. This study investigated the relationship between LBP and fractalkine in LPS-induced A549 cells and rat lung tissue in an ARDS rat model.

Methods

A549 cells were transfected with LBP or LBP shRNA plasmid DNA or pretreated with SB203580 or SC-514 following LPS treatment. An ARDS rat model was established using LPS with or without LBPK95A, SB203580, or SC-514 treatment. RT-PCR, western blotting, ELISA, immunofluorescence, coimmunoprecipitation, and immunohistochemical staining were used to study the expression of fractalkine and LBP and p38 MAPK and p65 NF-κB activities.

Results

LPS increased LBP and reduced fractalkine. LBP overexpression further decreased LPS-induced downregulation of fractalkine and p38 MAPK and p65 NF-κB activation; LBP gene silencing, SB203580, and SC-514 suppressed LPS-induced downregulation of fractalkine and p38 MAPK and p65 NF-κB activation in A549 cells. LBP and fractalkine in lung tissue were increased and decreased, respectively, following LPS injection. LBPK95A, SB203580, and SC-514 ameliorated LPS-induced rat lung injury and suppressed LPS-induced downregulation of fractalkine by decreasing phospho-p38 MAPK and p65 NF-κB.

Conclusions

The results indicate that LBP downregulates fractalkine expression in LPS-induced A549 cells and in an ARDS rat model through activation of p38 MAPK and NF-κB.

Electroporation-mediated delivery of the FER gene in the resolution of trauma-related fatal pneumonia

Injured patients with lung contusion (LC) are at risk of developing bacterial pneumonia (PNA) followed by sepsis and death. A recent genome-wide association study (GWAS) showed FER gene expression positively correlating with survival rates among individuals with above conditions. We sought to determine whether electroporation (EP)-mediated delivery of FER gene could indeed improve survival, in a lethal model of combined LC and PNA. C57BL/6 mice sustained unilateral LC, which preceded a 500 Klebsiella colony forming unit (CFU) inoculation by 6 h. In-between these insults, human FER plasmid (pFER) was introduced into the lungs followed by eight EP pulses applied externally (10 ms at 200 V cm^-1). Control groups included EP of empty vector (pcDNA3) or Na⁺/K⁺-ATPase genes (pPump) and no treatment (LC+PNA). We recorded survival, histology, lung mechanics, bronchial alveolar lavage (BAL) fluid, FER and inflammatory gene expression and bacteriology. The data show that 7-day survival was significantly improved by pFER compared with control groups. pFER increased BAL monocytes and activated antibacterial response genes (nitric oxide synthase (NOS), Fizz). pFER treatment showed decreased lung and blood Klebsiella counts reaching, in some cases, complete sterilization. In conclusion, FER gene delivery promoted survival in LC+PNA mice via recruitment of activated immune cells, improving efficiency of bacterial clearance within contused lung.

Matrine Attenuates COX-2 and ICAM-1 Expressions in Human Lung Epithelial Cells and Prevents Acute Lung Injury in LPS-Induced Mice

Matrine is isolated from Sophora flavescens and shows anti-inflammatory effects in macrophages. Here we evaluated matrine's suppressive effects on cyclooxygenase 2 (COX-2) and intercellular adhesion molecule-1 (ICAM-1) expressions in lipopolysaccharide- (LPS-) stimulated human lung epithelial A549 cells. Additionally, BALB/c mice were given various matrine doses by intraperitoneal injection, and then lung injury was induced via intratracheal instillation of LPS. In LPS-stimulated A549 cells, matrine inhibited the productions of interleukin-8 (IL-8), monocyte chemotactic protein-1, and IL-6 and decreased COX-2 expression. Matrine treatment also decreased ICAM-1 protein expression and suppressed the adhesion of neutrophil-like cells to inflammatory A549 cells. In vitro results demonstrated that matrine significantly inhibited mitogen-activated protein kinase phosphorylation and decreased nuclear transcription factor kappa-B subunit p65 protein translocation into the nucleus. In vivo data indicated that matrine significantly inhibited neutrophil infiltration and suppressed productions of tumor necrosis factor-α and IL-6 in mouse bronchoalveolar lavage fluid and serum. Analysis of lung tissue showed that matrine decreased the gene expression of proinflammatory cytokines, chemokines, COX-2, and ICAM-1. Our findings suggest that matrine improved lung injury in mice and decreased the inflammatory response in human lung epithelial cells.