Usp14 deficiency removes α-synuclein by regulating S100A8/A9 in Parkinson's disease

Ubiquitin-proteasome system dysfunction triggers α-synuclein aggregation, a hallmark of neurodegenerative diseases, such as Parkinson's disease (PD). However, the crosstalk between deubiquitinating enzyme (DUBs) and α-synuclein pathology remains unclear. In this study, we observed a decrease in the level of ubiquitin-specific protease 14 (USP14), a DUB, in the cerebrospinal fluid (CSF) of PD patients, particularly females. Moreover, CSF USP14 exhibited a dual correlation with α-synuclein in male and female PD patients. To investigate the impact of USP14 deficiency, we crossed USP14 heterozygous mouse (USP14+/-) with transgenic A53T PD mouse (A53T-Tg) or injected adeno-associated virus (AAV) carrying human α-synuclein (AAV-hα-Syn) in USP14+/- mice. We found that Usp14 deficiency improved the behavioral abnormities and pathological α-synuclein deposition in female A53T-Tg or AAV-hα-Syn mice. Additionally, Usp14 inactivation attenuates the pro-inflammatory response in female AAV-hα-Syn mice, whereas Usp14 inactivation demonstrated opposite effects in male AAV-hα-Syn mice. Mechanistically, the heterodimeric protein S100A8/A9 may be the downstream target of Usp14 deficiency in female mouse models of α-synucleinopathies. Furthermore, upregulated S100A8/A9 was responsible for α-synuclein degradation by autophagy and the suppression of the pro-inflammatory response in microglia after Usp14 knockdown. Consequently, our study suggests that USP14 could serve as a novel therapeutic target in PD.

S100A9: The Unusual Suspect Connecting Viral Infection and Inflammation

The study of S100A9 in viral infections has seen increased interest since the COVID-19 pandemic. S100A8/A9 levels were found to be correlated with the severity of COVID-19 disease, cytokine storm, and changes in myeloid cell subsets. These data led to the hypothesis that S100A8/A9 proteins might play an active role in COVID-19 pathogenesis. This review explores the structures and functions of S100A8/9 and the current knowledge on the involvement of S100A8/A9 and its constituents in viral infections. The potential roles of S100A9 in SARS-CoV-2 infections are also discussed.

Intestinal inflammation marker calprotectin regulates epithelial intestinal zinc metabolism and proliferation in mouse jejunal organoids

Calprotectin (CP), a heterodimer of S100A8 and S100A9, is expressed by neutrophils and a number of innate immune cells and is used widely as a marker of inflammation, particularly intestinal inflammation. CP is a ligand for toll-like receptor 4 (TLR4) and the receptor for advanced glycation end products (RAGE). In addition, CP can act as a microbial modulatory agent via a mechanism termed nutritional immunity, depending on metal binding, most notably Zn2+. The effects on the intestinal epithelium are largely unknown. In this study we aimed to characterize the effect of calprotectin on mouse jejunal organoids as a model epithelium, focusing on Zn2+ metabolism and cell proliferation. CP addition upregulated the expression of the Zn2+ absorptive transporter Slc39a4 and of methallothionein Mt1 in a Zn2+-sensitive manner, while downregulating the expression of the Zn2+ exporter Slc30a2 and of methallothionein 2 (Mt2). These effects were greatly attenuated with a CP variant lacking the metal binding capacity. Globally, these observations indicate adaptation to low Zn2+ levels. CP had antiproliferative effects and reduced the expression of proliferative and stemness genes in jejunal organoids, effects that were largely independent of Zn2+ chelation. In addition, CP induced apoptosis modestly and modulated antimicrobial gene expression. CP had no effect on epithelial differentiation. Overall, CP exerts modulatory effects in murine jejunal organoids that are in part related to Zn2+ sequestration and partially reproduced in vivo, supporting the validity of mouse jejunal organoids as a model for mouse epithelium.

miRNA-132-5p mediates a negative feedback regulation of IL-8 secretion through S100A8/A9 downregulation in neutrophil-like HL-60 cells

Background

Neutrophils are an important source of pro-inflammatory and immunomodulatory cytokines. This makes neutrophils efficient drivers of interactions with immune and non-immune cells to maintain homeostasis and modulate the inflammatory process by notably regulating the release of cytokines. Ca2+-dependent regulatory mechanism encompassing cytokine secretion by neutrophils are not still identified. In this context, we propose to define new insights on the role of Ca2+-binding proteins S100A8/A9 and on the regulatory role of miRNA-132-5p, which was identified as a regulator of S100A8/A9 expression, on IL-8 secretion.

Methods

Differentiated HL-60 cells, a human promyelocytic leukemia cell line that can be induced to differentiate into neutrophil-like cells, were used as a model of human neutrophils and treated with N- formyl-methionyl-leucyl-phenylalanine (fMLF), a bacterial peptide that activates neutrophils. shRNA knockdown was used to define the role of selected targets (S100A8/A9 and miRNA-132-5p) on IL-8 secretion.

Results and discussion

Different types of cytokines engage different signaling pathways in the secretion process. IL-8 release is tightly regulated by Ca2+ binding proteins S100A8/A9. miRNA-132-5p is up-regulated over time upon fMLF stimulation and decreases S100A8/A9 expression and IL-8 secretion.

Conclusion

These findings reveal a novel regulatory loop involving S100A8/A9 and miRNA-132-5p that modulates IL-8 secretion by neutrophils in inflammatory conditions. This loop could be a potential target for therapeutic intervention in inflammatory diseases.

Exploration of the role of oxidative stress-related genes in LPS-induced acute lung injury via bioinformatics and experimental studies

During the progression of acute lung injury (ALI), oxidative stress and inflammatory responses always promote each other. The datasets analyzed in this research were acquired from the Gene Expression Omnibus (GEO) database. The Weighted Gene Co-expression Network Analysis (WGCNA) and limma package were used to obtain the ALI-related genes (ALIRGs) and differentially expressed genes (DEGs), respectively. In total, two biological markers (Gch1 and Tnfaip3) related to oxidative stress were identified by machine learning algorithms, Receiver Operator Characteristic (ROC), and differential expression analyses. The area under the curve (AUC) value of biological markers was greater than 0.9, indicating an excellent power to distinguish between ALI and control groups. Moreover, 15 differential immune cells were selected between the ALI and control samples, and they were correlated to biological markers. The transcription factor (TF)-microRNA (miRNA)-Target network was constructed to explore the potential regulatory mechanisms. Finally, based on the quantitative reverse transcription polymerase chain reaction (qRT-PCR), the expression of Gch1 and Tnfaip3 was significantly higher in ALI lung tissue than in healthy controls. In conclusion, the differences in expression profiles between ALI and normal controls were found, and two biological markers were identified, providing a research basis for further understanding the pathogenesis of ALI.

Single-cell analysis reveals the immune heterogeneity and interactions in lungs undergoing hepatic ischemia-reperfusion

Hepatic ischemia-reperfusion IR (HIR) is an unavoidable pathophysiological process during liver transplantation, resulting in systematic sterile inflammation and remote organ injury. Acute lung injury (ALI) is a serious complication after liver transplantation with high postoperative morbidity and mortality. However, the underlying mechanism is still unclear. To assess the phenotype and plasticity of various cell types in the lung tissue microenvironment after HIR at the single-cell level, single-cell RNA sequencing (scRNA-seq) was performed using the lungs from HIR-induced mice. In our results, we identified 23 cell types in the lungs after HIR and found that this highly complex ecosystem was formed by subpopulations of bone marrow-derived cells that signaled each other and mediated inflammatory responses in different states and different intervals. We described the unique transcriptional profiles of lung cell clusters and discovered two novel cell subtypes (Tspo+Endothelial cells and Vcan+ monocytes), as well as the endothelial cell-immune cell and immune cell-T cell clusters interactome. In addition, we found that S100 calcium binding protein (S100a8/a9), specifically and highly expressed in immune cell clusters of lung tissues and exhibited detrimental effects. Finally, the cellular landscape of the lung tissues after HIR was established, highlighting the heterogeneity and cellular interactions between major immune cells in HIR-induced lungs. Our findings provided new insights into the mechanisms of HIR-induced ALI and offered potential therapeutic target to prevent ALI after liver transplantation.

S100a9 Protects Against the Effects of Repeated Social Defeat Stress

Background

Posttraumatic stress disorder, a consequence of psychological trauma, is associated with increased inflammation and an elevated risk of developing comorbid inflammatory diseases. However, the mechanistic link between this mental health disorder and inflammation remains elusive. We previously found that S100a8 and S100a9 messenger RNA, genes that encode the protein calprotectin, were significantly upregulated in T lymphocytes and positively correlated with inflammatory gene expression and the mitochondrial redox environment in these cells. Therefore, we hypothesized that genetic deletion of calprotectin would attenuate the inflammatory and redox phenotype displayed after psychological trauma.

Methods

We used a preclinical mouse model of posttraumatic stress disorder known as repeated social defeat stress (RSDS) combined with pharmacological and genetic manipulation of S100a9 (which functionally eliminates calprotectin). A total of 186 animals (93 control, 93 RSDS) were used in these studies.

Results

Unexpectedly, we observed worsening of behavioral pathology, inflammation, and the mitochondrial redox environment in mice after RSDS compared with wild-type animals. Furthermore, loss of calprotectin significantly enhanced the metabolic demand on T lymphocytes, suggesting that this protein may play an undescribed role in mitochondrial regulation. This was further supported by single-cell RNA sequencing analysis demonstrating that RSDS and loss of S100a9 primarily altered genes associated with mitochondrial function and oxidative phosphorylation.

Conclusions

These data demonstrate that the loss of calprotectin potentiates the RSDS-induced phenotype, which suggests that its observed upregulation after psychological trauma may provide previously unexplored protective functions.

Galactomannan-graft-poly(methyl methacrylate) nanoparticles induce an anti-inflammatory phenotype in human macrophages

Macrophages are immune cells that can be activated into either pro-inflammatory M1 or anti-inflammatory M2 phenotypes. Attempts to modulate macrophage phenotype using drugs have been limited by targeting issues and systemic toxicity. This study investigates the effect of drug-free self-assembled hydrolyzed galactomannan-poly(methyl methacrylate) (hGM-g-PMMA) nanoparticles on the activation of the human monocyte-derived macrophage THP-1 cell line. Nanoparticles are cell compatible and are taken up by macrophages. RNA-sequencing analysis of cells exposed to NPs reveal the upregulation of seven metallothionein genes. Additionally, the secretion of pro-inflammatory and anti-inflammatory cytokines upon exposure of unpolarized macrophages and M1-like cells obtained by activation with lipopolysaccharide + interferon-γ to the NPs is reduced and increased, respectively. Finally, nanoparticle-treated macrophages promote fibroblast migration in vitro. Overall, results demonstrate that hGM-g-PMMA nanoparticles induce the release of anti-inflammatory cytokines by THP-1 macrophages, which could pave the way for their application in the therapy of different inflammatory conditions, especially by local delivery.

Targeted Transcriptional Analysis of IgA Vasculitis, IgA Nephropathy, and IgA-Dominant Infection-Related Glomerulonephritis Reveals Both Distinct and Overlapping Immune Signatures

Key Points

Skin IL-9, calprotectin, and KIR gene expression may be predictive of subsequent kidney involvement in patients with IgAV. Histologically similar patients with IgAN, IgAV, and IgA-IRGN can be distinguished by their immune transcriptomes. Kidney biopsies from patients with IgA-IRGN are enriched for transcripts involved in granulocyte chemotaxis.

Background

IgA vasculitis (IgAV), IgA nephropathy (IgAN), and IgA-dominant infection-related glomerulonephritis (IgA-IRGN) have shared histopathologic features, but differences in clinical management and prognosis. The most serious IgAV organ involvement is in the kidneys (IgAV nephritis). In this study, we hypothesized that targeted immune transcript profiling could aid in (1 ) predicting the development of IgAV nephritis in patients with cutaneous IgAV and (2 ) differentiating IgAN, IgAV, and IgA-IRGN.

Methods

RNA was extracted from 24 formalin-fixed paraffin-embedded tissue specimens (16 kidney, 8 skin) from 21 patients with IgAV nephritis (n=7), IgAN (n=5), and IgA-IRGN (n=4), and IgAV skin biopsies from patients with (n=3) and without (n=5) IgAV nephritis. Differential gene expression and gene set enrichment analysis were performed on a total of 594 transcripts (Nanostring immunology panel) profiled using the nCounter system.

Results

Skin biopsies in patients with IgAV who develop kidney involvement exhibit reduced S100A8/S100A9 , IL9 , and killer cell immunoglobulin-like receptor expression. The kidney tissue immune transcriptomes of IgAN, IgAV, and IgA-IRGN are largely overlapping. IgA-IRGN kidney biopsies are, however, uniquely enriched for transcripts involved in granulocyte chemotaxis.

Conclusion

This study identifies immune transcript signatures that may predict IgAV nephritis in skin biopsies and distinguish IgA-IRGN from IgAN and IgAV in kidney biopsies.

NUCLEAR FACTOR-ERYTHROID-2-RELATED FACTOR REGULATES SYSTEMIC AND PULMONARY BARRIER FUNCTION AND IMMUNE PROGRAMMING AFTER BURN AND INHALATION INJURY

ABSTRACT

Major burn injury is associated with systemic hyperinflammatory and oxidative stresses that encompass the wound, vascular, and pulmonary systems that contribute to complications and poor outcomes. These stresses are exacerbated if there is a combined burn and inhalation (B+I) injury, which leads to increases in morbidity and mortality. Nuclear factor-erythroid-2-related factor (NRF2) is a transcription factor that functions to maintain homeostasis during stress, in part by modulating inflammation and oxidative injury. We hypothesized that the NRF2-mediated homeostasis after burn alone and combined B-I injury is insufficient, but that pharmacological activation of the NRF2 pathway has the potential to reduce/reverse acute hyper inflammatory responses. We found that, after burn and B+I injury, Nrf2 -/- mice have higher mortality and exhibit greater pulmonary edema, vascular permeability, and exacerbated pulmonary and systemic proinflammatory responses compared with injured wild-type (WT) controls. Transcriptome analysis of lung tissue revealed specific Nrf2 -dependent dysregulated immune pathways after injury. In WT mice, we observed that B+I injury induces cytosolic, but not nuclear, accumulation of NRF2 protein in the lung microenvironment compared with sham-injured controls. Bardoxolone methyl (CDDO-Me)-containing microparticles (CDDO-MPs) were developed that allow for dilution in saline and stable release of CDDO-Me. When delivered intraperitoneally into mice 1 hour after B+I injury, CDDO-MPs significantly reduced mortality and cytokine dysfunction compared with untreated B-I animals. These data implicate the role of NRF2 regulation of pulmonary and systemic immune dysfunction after burn and B+I injury, and also a deficiency in controlling immune dysregulation. Selectively activating the NRF2 pathway may improve clinical outcomes in burn and B+I patients.

Protective effects of S100A8 on sepsis mortality: Links to sepsis risk in obesity and diabetes

Obesity and diabetes are independent risk factors for death during sepsis. S100A8, an alarmin, is related to inflammation, obesity, and diabetes. Here, we examine the role of S100A8 in sepsis of obesity and diabetes models. Injection of S100A8 prolongs the survival of septic mice induced by lethal endotoxemia, Escherichia coli injection, or cecal ligation and puncture. S100A8 decrease the LPS-induced expression of proinflammatory cytokines in peritoneal macrophages by inhibiting TLR4-mediated signals in an autocrine manner. db/db, ob/ob, and western diet-fed mice demonstrate reduced upregulation of S100A8 induced by LPS treatment in both serum and peritoneal cells. These mice also show shorter survival after LPS injection, and S100A8 supplementation prolonged the survival. While myelomonocytic cells-specific S100A8-deficient mice (Lyz2 ^cre :S100A8 ^{floxed/floxed} ) exhibit shorter survival after LPS treatment, S100A8 supplementation prolonged the survival. Thus, myelomonocytic cell-derived S100A8 is crucial for protection from sepsis, and S100A8 supplementation improves sepsis, particularly in mice with obesity and diabetes.

Intranasal Delivery of Recombinant S100A8 Protein Delays Lung Cancer Growth by Remodeling the Lung Immune Microenvironment

Lung cancer is the leading cause of cancer-related death worldwide. Increasing evidence indicates a critical role for chronic inflammation in lung carcinogenesis. S100A8 is a protein with reported pro- and anti-inflammatory functions. It is highly expressed in myeloid-derived suppressor cells (MDSC) that accumulate in the tumor microenvironment and abrogate effective anti-cancer immune responses. Mechanisms of MDSC-mediated immunosuppression include production of reactive oxygen species and nitric oxide, and depletion of L-arginine required for T cell function. Although S100A8 is expressed in MDSC, its role in the lung tumor microenvironment is largely unknown. To address this, mouse recombinant S100A8 was repeatedly administered intranasally to mice bearing orthotopic lung cancers. S100A8 treatment prolonged survival from 19 days to 28 days (p < 0.001). At midpoint of survival, whole lungs and bronchoalveolar lavage fluid (BALF) were collected and relevant genes/proteins measured. We found that S100A8 significantly lowered expression of cytokine genes and proteins that promote expansion and activation of MDSC in lungs and BALF from cancer-bearing mice. Moreover, S100A8 enhanced activities of antioxidant enzymes and suppressed production of nitrite to create a lung microenvironment conducive to cytotoxic lymphocyte expansion and function. In support of this, we found decreased MDSC numbers, and increased numbers of CD4⁺ T cells and natural killer T (NK-T) cells in lungs from cancer-bearing mice treated with S100A8. Ex-vivo treatment of splenocytes with S100A8 protein activated NK cells. Our results indicate that treatment with S100A8 may favourably modify the lung microenvironment to promote an effective immune response in lungs, thereby representing a new strategy that could complement current immunotherapies in lung cancer.

Exploratory Investigation of the Plasma Proteome Associated with the Endotheliopathy of Trauma

BACKGROUND

The endotheliopathy of trauma (EoT) is associated with increased mortality following injury. Herein, we describe the plasma proteome related to EoT in order to provide insight into the role of the endothelium within the systemic response to trauma.

METHODS

99 subjects requiring the highest level of trauma activation were included in the study. Enzyme-linked immunosorbent assays of endothelial and catecholamine biomarkers were performed on admission plasma samples, as well as untargeted proteome quantification utilizing high-performance liquid chromatography and tandem mass spectrometry.

RESULTS

Plasma endothelial and catecholamine biomarker abundance was elevated in EoT. Patients with EoT (n = 62) had an increased incidence of death within 24 h at 21% compared to 3% for non-EoT (n = 37). Proteomic analysis revealed that 52 out of 290 proteins were differentially expressed between the EoT and non-EoT groups. These proteins are involved in endothelial activation, coagulation, inflammation, and oxidative stress, and include known damage-associated molecular patterns (DAMPs) and intracellular proteins specific to several organs.

CONCLUSIONS

We report a proteomic profile of EoT suggestive of a surge of DAMPs and inflammation driving nonspecific activation of the endothelial, coagulation, and complement systems with subsequent end-organ damage and poor clinical outcome. These findings support the utility of EoT as an index of cellular injury and delineate protein candidates for therapeutic intervention.

S100A8 expression in oviduct mucosal epithelial cells is regulated by estrogen and affects mucosal immune homeostasis

Chronic inflammation can cause oviduct mucosal damage and immune dysfunction, leading to infertility, early pregnancy loss, ectopic pregnancy, tumors, and a decrease in reproductive capacities in female animals. Estrogen can suppress immune responses in different tissues and oviducts, and regulate the oviduct immune balance; however, the underlying mechanisms remain unclear. The objective of this study was to explore the mechanism of estrogen-regulated oviduct mucosal immunity and discover new estrogen targets for regulating oviduct mucosal immune homeostasis. Sheep oviduct epithelial cells (SOECs) were treated with 17-β estradiol (E2). Transcriptome sequencing and analysis showed differentially expressed S100 calcium-binding protein A (S100A) genes that may participate in the oviduct mucosa immunoregulation of estrogen. Quantitative polymerase chain reaction and immunocytochemistry analysis showed that S100A8 expression changed dynamically in E2-treated SOECs and peaked after 7 h of treatment. Estrogen nuclear receptors and G protein-coupled membrane receptors promoted E2-dependent S100A8 upregulation. The S100A8 gene was disrupted using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 method. Levels of inflammatory factors interleukin (IL)-1β and IL-4 were significantly upregulated in S100A8-knockdown SOECs, whereas those of the anti-inflammatory factor IL-10 was downregulated. Following S100A8 knockdown in SOECs treated with E2 for 7 h, IL-10 levels increased significantly. Estrogen affected oviduct mucosa immune function and dynamically regulated S100A8 in SOECs. S100A8 knockdown caused an excessive immune response, indicating that S100A8 is beneficial for maintaining immune homeostasis in the oviduct mucosa. Moreover, estrogen can compensate for the effect of S100A8 knockdown by upregulating IL-10.

Airway epithelial integrin β4-deficiency exacerbates lipopolysaccharide-induced acute lung injury

Airway epithelial cells, the first barrier of the respiratory tract, play an indispensable role in innate immunity. Integrin β4 (ITGB4) is a structural adhesion molecule that is involved in the pathological progression of acute inflammatory diseases and is downregulated in asthmatic patients. Research has shown that endothelial ITGB4 has proinflammatory properties in acute lung injury (ALI). However, the role of epithelial ITGB4 in a murine ALI model is still unknown. This study investigated the role of ITGB4 in lipopolysaccharide (LPS)-induced ALI. We found that ITGB4 in the airway epithelium had remarkably increased after the introduction of LPS in vivo and in vitro. Then, we constructed airway epithelial cell-specific ITGB4 knockout (ITGB4-/- ) mice to study its role in ALI. At a time point of 12 h after the tracheal injection of LPS, ITGB4-/- mice showed increased macrophages (mainly M1-type macrophages) and neutrophil infiltration into the lungs; inflammation-related proteins including interleukin (IL)-6, tumor necrosis factor, and IL-17A were significantly elevated compared to their levels in ITGB4+/+ mice. Furthermore, we investigated the role of ITGB4 in the anti-inflammatory response. Intriguingly, in the ITGB4-/-  + LPS group, we found significantly reduced expression of anti-inflammatory factors, including IL-10 messenger RNA (mRNA) and ARG-1 mRNA. We also observed that monocyte chemotactic protein (MCP-1) increased significantly both in vivo and in vitro. Airway epithelium activates macrophages, most likely driven by MCP-1, which we confirmed in the coculture of epithelia and macrophages. These phenomena indicate that ITGB4 in airway epithelial cells plays an important role in the process of inflammation and activation of macrophages in ALI. Overall, these data demonstrated a novel link between airway epithelial ITGB4 and the inflammatory response in LPS-induced ALI.

Inorganic polyphosphate from the immunobiotic Lactobacillus rhamnosus CRL1505 prevents inflammatory response in the respiratory tract

Lactobacillus (L.) rhamnosus CRL1505 accumulates inorganic polyphosphate (polyP) in its cytoplasm in response to environmental stress. The aim of this study was to evaluate the potential effects of polyP from the immunobiotic CRL1505 on an acute respiratory inflammation murine animal model induced by lipopolysaccharide (LPS).

First, the presence of polyP granules in the cytoplasm of CRL1505 strain was evidenced by specific staining. Then, it was demonstrated in the intracellular extracts (ICE) of CRL1505 that polyP chain length is greater than 45 phosphate residues. In addition, the functionality of the genes involved in the polyP metabolism (ppk, ppx1 and ppx2) was corroborated by RT-PCR. Finally, the possible effect of the ICE of CRL1505 strain containing polyP and a synthetic polyP was evaluated in vivo using a murine model of acute lung inflammation. It was observed that the level of cytokines pro-inflammatory (IL-17, IL-6, IL-2, IL-4, INF-γ) in serum was normalized in mice treated with ICE, which would indicate that polyP prevents the local inflammatory response in the respiratory tract. The potential application of ICE from L. rhamnosus CRL1505 as a novel bioproduct for the treatment of respiratory diseases is one of the projections of this work.

The S100 Protein Family as Players and Therapeutic Targets in Pulmonary Diseases

The S100 protein family consists of over 20 members in humans that are involved in many intracellular and extracellular processes, including proliferation, differentiation, apoptosis, Ca₂⁺ homeostasis, energy metabolism, inflammation, tissue repair, and migration/invasion. Although there are structural similarities between each member, they are not functionally interchangeable. The S100 proteins function both as intracellular Ca²⁺ sensors and as extracellular factors. Dysregulated responses of multiple members of the S100 family are observed in several diseases, including the lungs (asthma, chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, cystic fibrosis, pulmonary hypertension, and lung cancer). To this degree, extensive research was undertaken to identify their roles in pulmonary disease pathogenesis and the identification of inhibitors for several S100 family members that have progressed to clinical trials in patients for nonpulmonary conditions. This review outlines the potential role of each S100 protein in pulmonary diseases, details the possible mechanisms observed in diseases, and outlines potential therapeutic strategies for treatment.

Impact of Exercise Intensity on Calprotectin Levels in Healthy Volunteers and Patients with Inflammatory Rheumatic Diseases

Exercise influences inflammatory response and immune system performance. The regular practice of a moderate activity positively regulates immunity and the inflammatory process, while intensive training depresses it and enhances inflammatory marker secretion. Calprotectin is involved in the inflammatory process, promoting neutrophil recruitment, cell degranulation, and inflammatory mediators. Furthermore, calprotectin has been associated with various inflammatory diseases, including inflammatory rheumatic diseases. The present review explores the effect of exercise on calprotectin levels in both healthy and inflammatory rheumatic conditions. Data show that the intensity duration and the type of exercise modulate calprotectin levels and participant inflammatory status. The exact role of calprotectin in the exercise response is yet unknown. Calprotectin could constitute an interesting biomarker for monitoring both the effect of exercise on the inflammatory process in healthy volunteers and the efficiency of exercise treatment programs in a patient with inflammatory rheumatic disease.

Small Immunomodulatory Molecules as Potential Therapeutics in Experimental Murine Models of Acute Lung Injury (ALI)/Acute Respiratory Distress Syndrome (ARDS)

Background: Acute lung injury (ALI) or its most advanced form, acute respiratory distress syndrome (ARDS) is a severe inflammatory pulmonary process triggered by a variety of insults including sepsis, viral or bacterial pneumonia, and mechanical ventilator-induced trauma. Currently, there are no effective therapies available for ARDS. We have recently reported that a novel small molecule AVR-25 derived from chitin molecule (a long-chain polymer of N-acetylglucosamine) showed anti-inflammatory effects in the lungs. The goal of this study was to determine the efficacy of two chitin-derived compounds, AVR-25 and AVR-48, in multiple mouse models of ALI/ARDS. We further determined the safety and pharmacokinetic (PK) profile of the lead compound AVR-48 in rats. Methods: ALI in mice was induced by intratracheal instillation of a single dose of lipopolysaccharide (LPS; 100 µg) for 24 h or exposed to hyperoxia (100% oxygen) for 48 h or undergoing cecal ligation and puncture (CLP) procedure and observation for 10 days. Results: Both chitin derivatives, AVR-25 and AVR-48, showed decreased neutrophil recruitment and reduced inflammation in the lungs of ALI mice. Further, AVR-25 and AVR-48 mediated diminished lung inflammation was associated with reduced expression of lung adhesion molecules with improvement in pulmonary endothelial barrier function, pulmonary edema, and lung injury. Consistent with these results, CLP-induced sepsis mice treated with AVR-48 showed a significant increase in survival of the mice (80%) and improved lung histopathology in the treated CLP group. AVR-48, the lead chitin derivative compound, demonstrated a good safety profile. Conclusion: Both AVR-25 and AVR-48 demonstrate the potential to be developed as therapeutic agents to treat ALI/ARDS.

Calprotectin in Lung Diseases

Calprotectin (CLP) is a heterodimer formed by two S-100 calcium-binding cytosolic proteins, S100A8 and S100A9. It is a multifunctional protein expressed mainly by neutrophils and released extracellularly by activated or damaged cells mediating a broad range of physiological and pathological responses. It has been more than 20 years since the implication of S100A8/A9 in the inflammatory process was shown; however, the evaluation of its role in the pathogenesis of respiratory diseases or its usefulness as a biomarker for the appropriate diagnosis and prognosis of lung diseases have only gained attention in recent years. This review aimed to provide current knowledge regarding the potential role of CLP in the pathophysiology of lung diseases and describe how this knowledge is, up until now, translated into daily clinical practice. CLP is involved in numerous cellular processes in lung health and disease. In addition to its anti-microbial functions, CLP also serves as a molecule with pro- and anti-tumor properties related to cell survival and growth, angiogenesis, DNA damage response, and the remodeling of the extracellular matrix. The findings of this review potentially introduce CLP in daily clinical practice within the spectrum of respiratory diseases.

iRGD conjugated nimbolide liposomes protect against endotoxin induced acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a deadly respiratory illness associated with refractory hypoxemia and pulmonary edema. The recent pandemic outbreak of COVID-19 is associated with severe pneumonia and inflammatory cytokine storm in the lungs. The anti-inflammatory phytomedicine nimbolide (NIM) may not be feasible for clinical translation due to poor pharmacokinetic properties and lack of suitable delivery systems. To overcome these barriers, we have developed nimbolide liposomes conjugated with iRGD peptide (iRGD-NIMLip) for targeting lung inflammation. It was observed that iRGD-NIMLip treatment significantly inhibited oxidative stress and cytokine storm compared to nimbolide free-drug (f-NIM), nimbolide liposomes (NIMLip), and exhibited superior activity compared to dexamethasone (DEX). iRGD-NIMLip abrogated the LPS induced p65 NF-κB, Akt, MAPK, Integrin β3 and β5, STAT3, and DNMT1 expression. Collectively, our results demonstrate that iRGD-NIMLip could be a promising novel drug delivery system to target severe pathological consequences observed in ARDS and COVID-19 associated cytokine storm.

Emerging roles of neutrophil-borne S100A8/A9 in cardiovascular inflammation

Elevated neutrophil count is associated with higher risk of major adverse cardiac events including myocardial infarction and early development of heart failure. Neutrophils contribute to cardiac damage through a number of mechanisms, including attraction of other immune cells and release of inflammatory mediators. Recently, a number of independent studies have reported a causal role for neutrophil-derived alarmins (i.e. S100A8/A9) in inducing inflammation and cardiac injury following myocardial infarction (MI). Furthermore, a positive correlation between serum S100A8/A9 levels and major adverse cardiac events (MACE) in MI patients was also observed implying that targeting neutrophils or their inflammatory cargo could be beneficial in reducing heart failure. However, contradictory to this idea, neutrophils and neutrophil-derived S100A8/A9 also seem to play a vital role in the resolution of inflammation. Thus, a better understanding of how neutrophils balance these seemingly contrasting functions would allow us to develop effective therapies that preserve the inflammation-resolving function while restricting the damage caused by inflammation. In this review, we specifically discuss the mechanisms behind neutrophil-derived S100A8/A9 in promoting inflammation and resolution in the context of MI. We also provide a perspective on how neutrophils could be potentially targeted to ameliorate cardiac inflammation and the ensuing damage.

S100 family proteins in inflammation and beyond

The S100 family proteins possess a variety of intracellular and extracellular functions. They interact with multiple receptors and signal transducers to regulate pathways that govern inflammation, cell differentiation, proliferation, energy metabolism, apoptosis, calcium homeostasis, cell cytoskeleton and microbial resistance. S100 proteins are also emerging as novel diagnostic markers for identifying and monitoring various diseases. Strategies aimed at targeting S100-mediated signaling pathways hold a great potential in developing novel therapeutics for multiple diseases. In this chapter, we aim to summarize the current knowledge about the role of S100 family proteins in health and disease with a major focus on their role in inflammatory conditions.

Enhanced myelopoiesis and aggravated arthritis in S100a8-deficient mice

Expressed strongly by myeloid cells, damage-associated molecular pattern (DAMP) proteins S100A8 and S100A9 are found in the serum of patients with infectious and autoimmune diseases. Compared to S100A9, the role of S100A8 is controversial. We investigated its biological activity in collagen-induced arthritis using the first known viable and fertile S100a8-deficient (S100a8^-/-) mouse. Although comparable to the wild type (WT) in terms of lymphocyte distribution in blood and in the primary and secondary lymphoid organs, S100a8^-/- mice had increased numbers of neutrophils, monocytes and dendritic cells in the blood and bone marrow, and these all expressed myeloid markers such as CD11b, Ly6G and CD86 more strongly. Granulocyte-macrophage common precursors were increased in S100a8^-/- bone marrow and yielded greater numbers of macrophages and dendritic cells in culture. The animals also developed more severe arthritic disease leading to aggravated osteoclast activity and bone destruction. These findings were correlated with increased inflammatory cell infiltration and cytokine secretion in the paws. This study suggests that S100A8 is an anti-inflammatory DAMP that regulates myeloid cell differentiation, thereby mitigating the development of experimental arthritis.

The relationship between DJ-1 and S100A8 in human primary alveolar type II cells in emphysema

Pulmonary emphysema is characterized by alveolar type II (ATII) cell death, destruction of alveolar wall septa, and irreversible airflow limitation. Cigarette smoke induces oxidative stress and is the main risk factor for this disease development. ATII cells isolated from nonsmokers, smokers, and patients with emphysema were used for this study. ATII cell apoptosis in individuals with this disease was detected. DJ-1 and S100A8 have cytoprotective functions against oxidative stress-induced cell injury. Reduced DJ-1 and S100A8 interaction was found in ATII cells in patients with emphysema. The molecular function of S100A8 was determined by an analysis of the oxidation status of its cysteine residues using chemoselective probes. Decreased S100A8 sulfination was observed in emphysema patients. In addition, its lower levels correlated with higher cell apoptosis induced by cigarette smoke extract in vitro. Cysteine at position 106 within DJ-1 is a central redox-sensitive residue. DJ-1 C106A mutant construct abolished the cytoprotective activity of DJ-1 against cell injury induced by cigarette smoke extract. Furthermore, a molecular and complementary relationship between DJ-1 and S100A8 was detected using gain- and loss-of-function studies. DJ-1 knockdown sensitized cells to apoptosis induced by cigarette smoke extract, and S100A8 overexpression provided cytoprotection in the absence of DJ-1. DJ-1 knockout mice were more susceptible to ATII cell apoptosis induced by cigarette smoke compared with wild-type mice. Our results indicate that the impairment of DJ-1 and S100A8 function may contribute to cigarette smoke-induced ATII cell injury and emphysema pathogenesis.

Loss of myeloid-specific protein phosphatase 2A enhances lung injury and fibrosis and results in IL-10-dependent sensitization of epithelial cell apoptosis

Protein phosphatase 2A (PP2A), a ubiquitously expressed Ser/Thr phosphatase is an important regulator of cytokine signaling and cell function. We previously showed that myeloid-specific deletion of PP2A (LysM^crePP2A^-/-) increased mortality in a murine peritoneal sepsis model. In the current study, we assessed the role of myeloid PP2A in regulation of lung injury induced by lipopolysaccharide (LPS) or bleomycin delivered intratracheally. LysM^crePP2A^-/- mice experienced increased lung injury in response to both LPS and bleomycin. LysM^crePP2A^-/- mice developed more exuberant fibrosis in response to bleomycin, elevated cytokine responses, and chronic myeloid inflammation. Bone marrow-derived macrophages (BMDMs) from LysM^crePP2A^-/- mice showed exaggerated inflammatory cytokine release under conditions of both M1 and M2 activation. Notably, secretion of IL-10 was elevated under all stimulation conditions, including activation of BMDMs by multiple Toll-like receptor ligands. Supernatants collected from LPS-stimulated LysM^crePP2A^-/- BMDMs induced epithelial cell apoptosis in vitro but this effect was mitigated when IL-10 was also depleted from the BMDMs by crossing LysM^crePP2A^-/- mice with systemic IL-10^-/- mice (LysM^crePP2A^-/- × IL-10^-/-) or when IL-10 was neutralized. Despite these findings, IL-10 did not directly induce epithelial cell apoptosis but sensitized epithelial cells to other mediators from the BMDMs. Taken together our results demonstrate that myeloid PP2A regulates production of multiple cytokines but that its effect is most pronounced on IL-10 production. Furthermore, IL-10 sensitizes epithelial cells to apoptosis in response to myeloid-derived mediators, which likely contributes to the pathogenesis of lung injury and fibrosis in this model.

S100A8 Protects Human Primary Alveolar Type II Cells against Injury and Emphysema

Pulmonary emphysema is characterized by alveolar wall destruction, and cigarette smoking is the main risk factor in this disease development. S100A8 is a member of the S100 protein family, with an oxidative stress-related and antiinflammatory role. The mechanisms of human alveolar type II (ATII) cell injury contributing to emphysema pathophysiology are not completely understood. We wanted to determine whether S100A8 can protect ATII cells against injury induced by cigarette smoke and this disease development. We used freshly isolated ATII cells from nonsmoking and smoking organ donors, as well as patients with emphysema to determine S100A8 function. S100A8 protein and mRNA levels were low in individuals with this disease and correlated with its severity as determined by using lung tissue from areas with mild and severe emphysema obtained from the same patient. Its expression negatively correlated with high oxidative stress as observed by 4-hydroxynonenal levels. We also detected decreased serine phosphorylation within S100A8 by PKAα in this disease. This correlated with increased S100A8 ubiquitination by SYVN1. Moreover, we cultured ATII cells isolated from nonsmokers followed by treatment with cigarette smoke extract. We found that this exposure upregulated S100A8 expression. We also confirmed the cytoprotective role of S100A8 against cell injury using gain- and loss-of-function approaches in vitro. S100A8 knockdown sensitized cells to apoptosis induced by cigarette smoke. In contrast, S100A8 overexpression rescued cell injury. Our results suggest that S100A8 protects ATII cells against injury and cigarette smoke-induced emphysema. Targeting S100A8 may provide a potential therapeutic strategy for this disease.

Calprotectin protects against experimental colonic inflammation in mice

BACKGROUND AND PURPOSE

Calprotectin is a heterodimer composed of two myeloid-related proteins, S100A8 and S100A9, that is abundant in neutrophils and monocytes/macrophages. Faecal levels of calprotectin are used routinely to monitor inflammatory bowel disease activity.

EXPERIMENTAL APPROACH

We aimed to assess the role of calprotectin in intestinal inflammation, using the dextran sulfate sodium model of colitis in mice. Calprotectin was administered (50 or 100 μg·day-1 ) by the intrarectal or by i.p. injection (50 μg·day-1 only). The condition of the mice was characterized by morphological and biochemical methods.

KEY RESULTS

Intrarectal calprotectin protected significantly against colitis, as shown by lower levels of macroscopic and microscopic damage, colonic myeloperoxidase activity and decreased expression of TNFα and toll-like receptor 4. IL-17 production by spleen and mesenteric lymph node cells was reduced. Calprotectin had no effect on body weight loss or colonic thickening. There were no effects of calprotectin after i.p. injection. Calprotectin had virtually no effects in control, non-colitic mice. Calprotectin had almost no effect on the colonic microbiota but enhanced barrier function. Treatment of rat IEC18 intestinal epithelial cells in vitro with calprotectin induced output of the chemokines CXL1 and CCL2, involving the receptor for advanced glycation end products- and NFκB.

CONCLUSION AND IMPLICATIONS

Calprotectin exerted protective effects in experimental colitis when given by the intrarectal route, by actions that appear to involve effects on the epithelium.

S100A8/A9 in Inflammation

S100A8 and S100A9 (also known as MRP8 and MRP14, respectively) are Ca²⁺ binding proteins belonging to the S100 family. They often exist in the form of heterodimer, while homodimer exists very little because of the stability. S100A8/A9 is constitutively expressed in neutrophils and monocytes as a Ca²⁺ sensor, participating in cytoskeleton rearrangement and arachidonic acid metabolism. During inflammation, S100A8/A9 is released actively and exerts a critical role in modulating the inflammatory response by stimulating leukocyte recruitment and inducing cytokine secretion. S100A8/A9 serves as a candidate biomarker for diagnosis and follow-up as well as a predictive indicator of therapeutic responses to inflammation-associated diseases. As blockade of S100A8/A9 activity using small-molecule inhibitors or antibodies improves pathological conditions in murine models, the heterodimer has potential as a therapeutic target. In this review, we provide a comprehensive and detailed overview of the distribution and biological functions of S100A8/A9 and highlight its application as a diagnostic and therapeutic target in inflammation-associated diseases.

Immune-related gene expression and physiological responses in rainbow trout (Oncorhynchus mykiss) after intraperitoneal administration of Rhodomyrtus tomentosa leaf extract: A potent phytoimmunostimulant

The immunostimulatory effects of Rhodomyrtus tomentosa leaf extract were evaluated in rainbow trout through changes in expression profile of genes involved in innate immune and antioxidant response, hematology and stress indicators. The concentrations of R. tomentosa at 10 and 100 μg per fish were administrated by intraperitoneal injection, alone or in combination with LPS. After 6 h of administration, the gene expression was measured in head kidney, spleen, and intestine. Results indicated that R. tomentosa exerted immunostimulatory effects by inducing the expression of il10, saa, hepcidin, and sod in head kidney and the expression of il10, tgfβ, and inos in intestine. In combination with LPS, the plant suppressed the expression of pro-inflammtory cytokine il1β, il8 and other consisting of saa and gpx1 in head kidney and il1β in spleen, pointing out its anti-inflammatory activities. Furthermore, the plant did not exert any impact on hematological parameters, but it was able to reduce cortisol levels when co-administered with LPS, indicating that R. tomentosa could attenuate stress response in rainbow trout. Our observations suggest that R. tomentosa induced the expression of genes involved in cytokine and innate immune response and modulated the physiological stress response as indicated by the suppressed cortisol in rainbow trout.

Probing the molecular regulation of lipopolysaccharide stress in piglet liver by comparative proteomics analysis

Lipopolysaccharide (LPS) can induce inflammatory responses in piglets, causing immunological stress and tissue damage. However, chronic LPS infection may lead to LPS-induced immunological stress resistance. The molecular mechanisms underlying LPS stress have not been fully elucidated. Here, we conducted a global comparative proteomics analysis to investigate the molecular regulation of LPS stress using an immunological stress model of weaned piglets. A shotgun-based SWATH-MS workflow was used for global proteomes of the piglet livers after 15-day LPS treatment. Out of 3700 quantified proteins, 93 proteins showed differential changes under LPS stress. Bioinformatics analysis indicated that the differentially expressed proteins were mainly involved in inflammatory response, oxidation-redox processes and defense reactions, and were enriched in a phagosome pathway. Several key proteins associated with oxidative stress (SOD2), inflammation response (STEAP4 and S100 family) and the phagosome pathway were verified by activity and targeted-MS analyses. The observed responses appear to mitigate hepatic damage due to excessive oxidative stress, inflammation, and repression of the phagosome pathway. Our results reveal that an increased STEAP4 expression in piglets appears involved in cellular regulation by LPS stress and subsequent immunological stress resistance. This study sheds new light on the mechanism of prevention and relieving injury by LPS-induced immune responses.

XB130 deficiency enhances lipopolysaccharide-induced septic response and acute lung injury

XB130 is a novel oncoprotein that promotes cancer cell survival, proliferation and migration. Its physiological function in vivo is largely unknown. The objective of this study was to determine the role of XB130 in lipopolysaccharide (LPS)-induced septic responses and acute lung injury. LPS was intraperitoneally administrated to Xb130 knockout (KO) and wild type (WT) mice. There was a significant weight loss in KO mice at Day 2 and significantly higher disease scores during the 7 days of observation. The levels of tumor necrosis factor-alpha, monocyte chemoattractant protein-1, interleukin-6 and interleukin-10 in the serum were significantly higher in KO mice at Day 2. In KO mice there were a significantly higher lung injury score, higher wet/dry lung weight ratio, more apoptotic cells and less proliferative cells in the lung. Macrophage infiltration was significantly elevated in the lung of KO mice. There was significantly increased number of p-GSK-3β positive cells in KO mice, which were mainly neutrophils and macrophages. XB130 is expressed in alveolar type I and type II cells in the lung. The expression in these cells was significantly reduced after LPS challenge. XB130 deficiency delayed the recovery from systemic septic responses, and the presence of XB130 in the alveolar epithelial cells may provide protective mechanisms by reducing cell death and promoting cell proliferation, and reducing pulmonary permeability.

Necrostatin-1 enhances the resolution of inflammation by specifically inducing neutrophil apoptosis

Neutrophils play a central role in innate immunity and are rapidly recruited to sites of infection and injury. Neutrophil apoptosis is essential for the successful resolution of inflammation. Necrostatin-1 (Nec-1,methyl-thiohydantoin-tryptophan (MTH-Trp)), is a potent and specific inhibitor of necroptosis[1] (a newly identified type of cell death representing a form of programmed necrosis or regulated non apoptotic cell death) by inhibiting the receptor interacting protein 1(RIP1) kinase. Here we report that Nec-1 specifically induces caspase-dependent neutrophils apoptosis and overrides powerful anti-apoptosis signaling from survival factors such as GM-CSF and LPS. We showed that Nec-1 markedly enhanced the resolution of established neutrophil-dependent inflammation in LPS-induced acute lung injury in mice. We also provided evidence that Nec-1 promoted apoptosis by reducing the expression of the anti-apoptotic protein Mcl-1 and increasing the expression of pro-apoptotic protein Bax. Thus, Nec-1 is not only an inhibitor of necroptosis, but also a promoter of apoptosis, of neutrophils, enhancing the resolution of established inflammation by inducing apoptosis of inflammatory cells. Our results suggest that Nec-1 may have potential roles for the treatment of diseases with increased or persistent inflammatory responses.

Alarmin S100A8 Activates Alveolar Epithelial Cells in the Context of Acute Lung Injury in a TLR4-Dependent Manner

Alveolar epithelial cells (AECs) are an essential part of the respiratory barrier in lungs for gas exchange and protection against pathogens. Damage to AECs occurs during lung injury and PAMPs/DAMPs have been shown to activate AECs. However, their interplay as well as the mechanism of AECs’ activation especially by the alarmin S100A8/A9 is unknown. Thus, our aim was to study the mechanism of activation of AECs (type I and type II) by S100A8 and/or lipopolysaccharide (LPS) and to understand the role of endogenous S100A8/A9 in neutrophil recruitment in the lung. For our studies, we modified a previous protocol for isolation and culturing of murine AECs. Next, we stimulated the cells with S100A8 and/or LPS and analyzed cytokine/chemokine release. We also analyzed the contribution of the known S100-receptors TLR4 and RAGE in AEC activation. In a murine model of lung injury, we investigated the role of S100A8/A9 in neutrophil recruitment to lungs. S100A8 activates type I and type II cells in a dose- and time-dependent manner which could be quantified by the release of IL-6, KC, and MCP-1. We here clearly demonstrate that AEC s are activated by S100A8 via a TLR4-dependent pathway. Surprisingly, RAGE, albeit mainly expressed in lung tissue, plays no role. Additionally, we show that S100A8/A9 is an essential factor for neutrophil recruitment to lungs. We, therefore, conclude that S100A8 promotes acute lung injury via Toll-like receptor 4-dependent activation of AECs.

Interleukin-10-Overexpressing Mesenchymal Stromal Cells Induce a Series of Regulatory Effects in the Inflammatory System and Promote the Survival of Endotoxin-Induced Acute Lung Injury in Mice Model

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are life-threatening inflammatory conditions with no effective pharmacological treatment. Previous studies suggested that mesenchymal stromal/stem cell (MSC) infusion resulted in better survival in mouse ALI models and presented low toxicity in human subjects. Therefore, in this study, we investigated the possibility of treating a murine model of ALI using MSCs with constant interleukin-10 overexpression (IL-10-MSC) by retroviral infection. ALI in mice was induced by intratracheal lipopolysaccharides (LPS) instillation. After 96 h, 80% of mice receiving IL-10-MSCs survived, whereas the survival rate of the mice receiving other treatments was only 20-50%. Mice receiving IL-10-MSCs also demonstrated significantly less weight loss (p < 0.01), and lower protein level and TNF concentration in the BAL (p < 0.01). Interestingly, IL-10-MSCs given to mice 3 and 1 day before ALI induction still conferred significant protection against ALI. While direct IL-10 transfusion resulted in an intensive, but transient peak in serum IL-10 level, IL-10-MSCs provided a milder, but more persistent increase in serum IL-10 level, together with significantly higher levels of IL-10-producing T cells and B cells, both in the spleen and in the lung. IL-10-MSCs given 3 days before LPS challenge resulted in higher pulmonary infiltration of IL-10-producing T cells and B cells in mice. On average, mice that survived the LPS challenge for 96 h presented higher pulmonary infiltration of IL-10-producing T cells and B cells than mice that deceased within the experimental period. Together, these results demonstrated that IL-10-MSCs offered superior protection against LPS-induced ALI when given before or at the time of ALI induction, and significantly increased the frequencies of IL-10-expressing T cells and B cells. IL-10-MSCs may thus represent a promising new treatment option in ALI/ARDS.

Myricitrin Modulates NADPH Oxidase-Dependent ROS Production to Inhibit Endotoxin-Mediated Inflammation by Blocking the JAK/STAT1 and NOX2/p47phox Pathways

Myricitrin, a naturally occurring polyphenol hydroxy flavonoid, has been reported to possess anti-inflammatory properties. However, the precise molecular mechanism of myricitrin's effects on LPS-induced inflammation is unclear. In the present study, myricitrin significantly alleviated acute lung injury in mice. Myricitrin also markedly suppressed the production of NO, TNF-α, IL-6, and MCP-1 in RAW264.7 macrophage cells. The inhibition of NO was concomitant with a decrease in the protein and mRNA levels of iNOS. The phosphorylation of JAKs and STAT-1 was abrogated by myricitrin. Furthermore, myricitrin inhibited the nuclear transfer and DNA binding activity of STAT1. The JAK-specific inhibitor ruxolitinib simulated the anti-inflammatory effect of myricitrin. However, myricitrin had no impact on the MAPK signalling pathway. Myricitrin attenuated the generation of intracellular ROS by inhibiting the assembly of components of the gp91^phox and p47^phox. Suppression of ROS generation using NAC or apocynin or by silencing gp91^phox and p47^phox all demonstrated that decreasing the level of ROS inhibited the LPS-induced inflammatory response. Collectively, these results confirmed that myricitrin exhibited anti-inflammatory activity by blocking the activation of JAKs and the downstream transcription factor STAT1, which may result from the downregulation of NOX2-dependent ROS production mediated by myricitrin.

T regulatory cells and dendritic cells protect against transfusion-related acute lung injury via IL-10

Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-related fatalities and is characterized by acute respiratory distress following blood transfusion. Donor antibodies are frequently involved; however, the pathogenesis and protective mechanisms in the recipient are poorly understood, and specific therapies are lacking. Using newly developed murine TRALI models based on injection of anti-major histocompatibility complex class I antibodies, we found CD4⁺CD25⁺FoxP3⁺ T regulatory cells (Tregs) and CD11c⁺ dendritic cells (DCs) to be critical effectors that protect against TRALI. Treg or DC depletion in vivo resulted in aggravated antibody-mediated acute lung injury within 90 minutes with 60% mortality upon DC depletion. In addition, resistance to antibody-mediated TRALI was associated with increased interleukin-10 (IL-10) levels, and IL-10 levels were found to be decreased in mice suffering from TRALI. Importantly, IL-10 injection completely prevented and rescued the development of TRALI in mice and may prove to be a promising new therapeutic approach for alleviating lung injury in this serious complication of transfusion.

Expression of Calgranulin Genes S100A8, S100A9 and S100A12 Is Modulated by n-3 PUFA during Inflammation in Adipose Tissue and Mononuclear Cells

Calgranulin genes (S100A8, S100A9 and S100A12) play key immune response roles in inflammatory disorders, including cardiovascular disease. Long-chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA) may have systemic and adipose tissue-specific anti-inflammatory and cardio-protective action. Interactions between calgranulins and the unsaturated fatty acid arachidonic acid (AA) have been reported, yet little is known about the relationship between calgranulins and the LC n-3 PUFA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). We explored tissue-specific action of calgranulins in the setting of evoked endotoxemia and n-3 PUFA supplementation. Expression of calgranulins in adipose tissue in vivo was assessed by RNA sequencing (RNASeq) before and after n-3 PUFA supplementation and evoked endotoxemia in the fenofibrate and omega-3 fatty acid modulation of endotoxemia (FFAME) Study. Subjects received n-3 PUFA (n = 8; 3600mg/day EPA/DHA) or matched placebo (n = 6) for 6–8 weeks, before completing an endotoxin challenge (LPS 0.6 ng/kg). Calgranulin genes were up-regulated post-LPS, with greater increase in n-3 PUFA (S100A8 15-fold, p = 0.003; S100A9 7-fold, p = 0.003; S100A12 28-fold, p = 0.01) compared to placebo (S100A8 2-fold, p = 0.01; S100A9 1.4-fold, p = 0.4; S100A12 5-fold, p = 0.06). In an independent evoked endotoxemia study, calgranulin gene expression correlated with the systemic inflammatory response. Through in vivo and in vitro interrogation we highlight differential responses in adipocytes and mononuclear cells during inflammation, with n-3 PUFA leading to increased calgranulin expression in adipose, but decreased expression in circulating cells. In conclusion, we present a novel relationship between n-3 PUFA anti-inflammatory action in vivo and cell-specific modulation of calgranulin expression during innate immune activation.

S100A8/A9 and S100A9 reduce acute lung injury

S100A8 and S100A9 are myeloid cell-derived proteins that are elevated in several types of inflammatory lung disorders. Pro- and anti-inflammatory properties are reported and these proteins are proposed to activate TLR4. S100A8 and S100A9 can function separately, likely through distinct receptors but a systematic comparison of their effects in vivo are limited. Here we assess inflammation in murine lung following S100A9 and S100A8/A9 inhalation. Unlike S100A8, S100A9 promoted mild neutrophil and lymphocyte influx, possibly mediated in part, by increased mast cell degranulation and selective upregulation of some chemokine genes, particularly CXCL-10. S100 proteins did not significantly induce proinflammatory mediators including TNF-α, interleukin-1β (IL-1β), IL-6 or serum amyloid A3 (SAA3). In contrast to S100A8, neither preparation induced S100A8 or IL-10 mRNA/protein in airway epithelial cells, or in tracheal epithelial cells in vitro. Like S100A8, S100A9 and S100A8/A9 reduced neutrophil influx in acute lung injury provoked by lipopolysaccharide (LPS) challenge but were somewhat less inhibitory, possibly because of differential effects on expression of some chemokines, IL-1β, SAA3 and IL-10. Novel common pathways including increased induction of an NAD⁺-dependent protein deacetylase sirtuin-1 that may reduce NF-κB signalling, and increased STAT3 activation may reduce LPS activation. Results suggest a role for these proteins in normal homeostasis and protective mechanisms in the lung.

Therapeutic Effects of Human Umbilical Cord-Derived Mesenchymal Stem Cells in Acute Lung Injury Mice

The incidence and mortality of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) are still very high, but stem cells show some promise for its treatment. Here we found that intratracheal administration of human umbilical cord-mesenchymal stem cells (UC-MSCs) significantly improved survival and attenuated the lung inflammation in lipopolysaccharide (LPS)-induced ALI mice. We also used the proteins-chip and bioinformatics to analyze interactions between UC-MSCs treatment and immune-response alternations of ALI mice. Then we demonstrated that UC-MSCs could inhibit the inflammatory response of mouse macrophage in ALI mice, as well as enhance its IL-10 expression. We provide data to support the concept that the therapeutic capacity of UC-MSCs for ALI was primarily through paracrine secretion, particularly of prostaglandin-E2 (PGE2). Furthermore, we showed that UC-MSCs might secrete a panel of factors including GM-CSF, IL-6 and IL-13 to ameliorate ALI. Our study suggested that UC-MSCs could protect LPS-induced ALI model by immune regulation and paracrine factors, indicating that UC-MSCs should be a promising strategy for ALI/ARDS.

Gelam honey attenuates ovalbumin-induced airway inflammation in a mice model of allergic asthma

Allergic asthma is a chronic inflammatory disorder of the pulmonary airways. Gelam honey has been proven to possess anti-inflammatory property with great potential to treat an inflammatory condition. However, the effect of ingestion of Gelam honey on allergic asthma has never been studied. This study aimed to investigate the efficacy of Gelam honey on the histopathological changes in the lungs of a mice model of allergic asthma. Forty-two Balb/c mice were divided into seven groups: control, I, II, III, IV, V and VI group. All groups except the control were sensitized and challenged with ovalbumin. Mice in groups I, II, III, IV, and V were given honey at a dose of 10% (v/v), 40% (v/v) and 80% (v/v), dexamethasone 3 mg/kg, and phosphate buffered saline (vehicle) respectively, orally once a day for 5 days of the challenged period. Mice were sacrificed 24 h after the last OVA challenged and the lungs were evaluated for histopathological changes by light microscopy. All histopathological parameters such as epithelium thickness, the number of mast cell and mucus expression in Group III significantly improved when compared to Group VI except for subepithelial smooth muscle thickness (p < 0.05). In comparing Group III and IV, all the improvements in histopathological parameters were similar. Also, Gelam honey showed a significant (p < 0.05) reduction in inflammatory cell infiltration and beta-hexosaminidase level in bronchoalveolar lavage fluid. In conclusion, we demonstrated that administration of high concentration of Gelam honey alleviates the histopathological changes of mice model of allergic asthma.

Identification of distinct genes associated with seawater aspiration‑induced acute lung injury by gene expression profile analysis

Seawater aspiration-induced acute lung injury (ALI) is a syndrome associated with a high mortality rate, which is characterized by severe hypoxemia, pulmonary edema and inflammation. The present study is the first, to the best of our knowledge, to analyze gene expression profiles from a rat model of seawater aspiration-induced ALI. Adult male Sprague-Dawley rats were instilled with seawater (4 ml/kg) in the seawater aspiration-induced ALI group (S group) or with distilled water (4 ml/kg) in the distilled water negative control group (D group). In the blank control group (C group) the rats' tracheae were exposed without instillation. Subsequently, lung samples were examined by histopathology; total protein concentration was detected in bronchoalveolar lavage fluid (BALF); lung wet/dry weight ratios were determined; and transcript expression was detected by gene sequencing analysis. The results demonstrated that histopathological alterations, pulmonary edema and total protein concentrations in BALF were increased in the S group compared with in the D group. Analysis of differential gene expression identified up and downregulated genes in the S group compared with in the D and C groups. A gene ontology analysis of the differential gene expression revealed enrichment of genes in the functional pathways associated with neutrophil chemotaxis, immune and defense responses, and cytokine activity. Kyoto Encyclopedia of Genes and Genomes analysis revealed that the cytokine-cytokine receptor interaction pathway was one of the most important pathways involved in seawater aspiration-induced ALI. In conclusion, activation of the cytokine-cytokine receptor interaction pathway may have an essential role in the progression of seawater aspiration-induced ALI, and the downregulation of tumor necrosis factor superfamily member 10 may enhance inflammation. Furthermore, IL-6 may be considered a biomarker in seawater aspiration-induced ALI.

Lipoxin A4 attenuates LPS-induced mouse acute lung injury via Nrf2-mediated E-cadherin expression in airway epithelial cells

A fundamental element of acute lung injury (ALI) is the inflammation that is part of the body's immune response to a variety of local or systemic stimuli. Lipoxins (LXs) are important endogenous lipids that mediate resolution of inflammation. Previously, we demonstrated that LXA4 reduced the LPS inhalation-induced pulmonary edema, neutrophil infiltration and TNF-α production in mice. With the same model, the current investigation focused on the role of the airway epithelium, a first-line barrier and a prime target of inhaled toxicants. We report that LXA4 strongly inhibited LPS-induced ALI in mice, in part by protecting the airway epithelium and preserving the E-cadherin expression and airway permeability. Using a cryo-imaging assay and fluorescence detection, LXA4 was shown to block LPS-induced ROS generation and preserve mitochondrial redox status both in vivo and in vitro. To further assess whether and how NF-E2-related factor 2 (Nrf2) was involved in the protective effect of LXA4, fluorescence resonance energy transfer (FRET) analysis was employed in human epithelial cell line (16HBE), to determine the relative distance between Nrf2 and its negative regulator or cytosolic inhibitor, Kelch-like ECH-associated protein 1 (Keap1). It provided us the evidence that LXA4 further promoted the dissociation of Nrf2 and Keap1 in LPS-treated 16HBE cells. The results also showed that LXA4 activates Nrf2 by phosphorylating it on Ser40 and triggering its nuclear translocation. Moreover, when the plasmid expression dominant negative mutation of Nrf2 was transfected as an inhibitor of wild-type Nrf2, the protective effect of LXA4 on E-cadherin expression was almost completely blocked. These results provide a new mechanism by which LXA4 inhibits LPS-induced ALI through Nrf2-mediated E-cadherin expression.

Δ9-Tetrahydrocannabinol-mediated epigenetic modifications elicit myeloid-derived suppressor cell activation via STAT3/S100A8

MDSCs are potent immunosuppressive cells that are induced during inflammatory responses, as well as by cancers, to evade the anti-tumor immunity. We recently demonstrated that marijuana cannabinoids are potent inducers of MDSCs. In the current study, we investigated the epigenetic mechanisms through which THC, an exogenous cannabinoid, induces MDSCs and compared such MDSCs with the naïve MDSCs found in BM of BL6 (WT) mice. Administration of THC into WT mice caused increased methylation at the promoter region of DNMT3a and DNMT3b in THC-induced MDSCs, which correlated with reduced expression of DNMT3a and DNMT3b. Furthermore, promoter region methylation was decreased at Arg1 and STAT3 in THC-induced MDSCs, and consequently, such MDSCs expressed higher levels of Arg1 and STAT3. In addition, THC-induced MDSCs secreted elevated levels of S100A8, a calcium-binding protein associated with accumulation of MDSCs in cancer models. Neutralization of S100A8 by use of anti-S100A8 (8H150) in vivo reduced the ability of THC to trigger MDSCs. Interestingly, the elevated S100A8 expression also promoted the suppressive function of MDSCs. Together, the current study demonstrates that THC mediates epigenetic changes to promote MDSC differentiation and function and that S100A8 plays a critical role in this process.

Myocardial Hypertrophic Preconditioning Attenuates Cardiomyocyte Hypertrophy and Slows Progression to Heart Failure Through Upregulation of S100A8/A9

BACKGROUND

Transient preceding brief ischemia provides potent cardioprotection against subsequent long ischemia, termed ischemic preconditioning. Here, we hypothesized that transient short-term hypertrophic stimulation would induce the expression of hypertrophy regression genes and render the heart resistant to subsequent hypertrophic stress, and slow the progression to heart failure, as well.

METHODS AND RESULTS

Cardiomyocyte hypertrophy was induced in mice by either transverse aortic constriction or an infusion of phenylephrine, and in neonatal rat ventricular cardiomyocytes by norepinephrine exposures. In the preconditioning groups, hypertrophic stimulation was provided for 1 to 7 days and then withdrawn for several days by either aortic debanding or discontinuing phenylephrine or norepinephrine treatment, followed by subsequent reexposure to the hypertrophic stimulus for the same period as in the control group. One or 6 weeks after transverse aortic constriction, the heart weight/body weight ratio was lower in the preconditioning group than in the control group, whereas the lung weight/body weight ratio was significantly decreased 6 weeks after transverse aortic constriction. Similar results were obtained in mice receiving phenylephrine infusion and neonatal rat ventricular cardiomyocytes stimulated with norepinephrine. Both mRNA and protein expression of S100A8 and S100A9 showed significant upregulation after the removal of hypertrophic stimulation and persisted for 6 weeks in response to reimposition of transverse aortic constriction. The treatment with recombinant S100A8/A9 inhibited norepinephrine-induced myocyte hypertrophy and reduced the expression of calcineurin and NFATc3, but the silencing of S100A8/A9 prevented such changes.

CONCLUSIONS

Preconditioning with prohypertrophic factors exerts an antihypertrophic effect and slows the progression of heart failure, indicating the existence of the phenomenon for hypertrophic preconditioning.

Effect of Hangeshashinto on calprotectin expression in human oral epithelial cells

Oral epithelial cells produce antimicrobial peptides (AMPs) to prevent microbial infection. Calprotectin (S100A8/S100A9) is one of these AMPs in oral epithelial cells, the expression of which is up-regulated by interleukin-1α (IL-1α). Hangeshashinto (HST) is a traditional Japanese herbal medicine that has anti-inflammatory effects. The purpose of this study was to investigate the effect of HST on the expression of calprotectin through the regulation of IL-1α in oral epithelial cells. Human oral epithelial cells (TR146) were cultured with HST in the presence or absence of anti-IL-1α antibody or IL-1 receptor antagonist, or with six major components of HST (3,4-dihydroxybenzaldehyde, baicalin, ginsenoside Rb1, glycyrrhizin, oleanolic acid and berberine). The expression of S100A8, S100A9, other AMPs and cytokine mRNAs was examined by RT-PCR and quantitative real-time PCR. Calprotectin expression and IL-1α secretion were investigated by ELISA. HST (6 μg/ml) increased the expression of S100A8/S100A9 mRNAs and calprotectin protein, and also up-regulated β-defensin 2 (DEFB4) and S100A7 expression. The expression of IL-1α mRNA and its protein was slightly but significantly increased by HST. A neutralizing antibody against IL-1α and IL-1 receptor antagonist inhibited HST-up-regulated S100A8/S100A9 mRNA expression. Although 3,4-dihydroxybenzaldehyde, baicalin and ginsenoside Rb1 as HST components increased S100A8/S100A9 expression, oleanolic acid and berberine decreased their expression. These results suggest that HST increases the expression of calprotectin, DEFB4 and S100A7 in oral epithelial cells. In response to HST, up-regulation of calprotectin expression may be partially induced via IL-1α.

Soluble factors from Lactobacillus reuteri CRL1098 have anti-inflammatory effects in acute lung injury induced by lipopolysaccharide in mice

We have previously demonstrated that Lactobacillus reuteri CRL1098 soluble factors were able to reduce TNF-α production by human peripheral blood mononuclear cells. The aims of this study were to determine whether L. reuteri CRL1098 soluble factors were able to modulate in vitro the inflammatory response triggered by LPS in murine macrophages, to gain insight into the molecular mechanisms involved in the immunoregulatory effect, and to evaluate in vivo its capacity to exert anti-inflammatory actions in acute lung injury induced by LPS in mice. In vitro assays demonstrated that L. reuteri CRL1098 soluble factors significantly reduced the production of pro-inflammatory mediators (NO, COX-2, and Hsp70) and pro-inflammatory cytokines (TNF-α, and IL-6) caused by the stimulation of macrophages with LPS. NF-kB and PI3K inhibition by L. reuteri CRL1098 soluble factors contributed to these inhibitory effects. Inhibition of PI3K/Akt pathway and the diminished expression of CD14 could be involved in the immunoregulatory effect. In addition, our in vivo data proved that the LPS-induced secretion of the pro-inflammatory cytokines, inflammatory cells recruitment to the airways and inflammatory lung tissue damage were reduced in L. reuteri CRL1098 soluble factors treated mice, providing a new way to reduce excessive pulmonary inflammation.

TLR9 ligands induce S100A8 in macrophages via a STAT3-dependent pathway which requires IL-10 and PGE2

S100A8 and S100A9 are highly-expressed calcium-binding proteins in neutrophils and monocytes, and in subsets of macrophages in inflammatory lesions. Unmethylated CpG motifs found in bacterial and viral DNA are potent activators of innate immunity via Toll-like receptor 9 (TLR9). S100A8, but not S100A9, mRNA and protein was directly induced by CpG-DNA in murine and human macrophages. Induction in murine macrophages peaked at 16 h. CpG-DNA-induced S100A8 required de novo protein synthesis; IL-10 and Prostaglandin E2 (PGE2) synergistically enhanced expression and promoted earlier gene induction. Inhibitors of endogenous IL-10, PGE2, and the E prostanoid (EP) 4 receptor strongly suppressed S100A8 expression, particularly when combined. Thus, S100A8 induction by E. coli DNA required both IL-10 and PGE2/EP4 signaling. The MAPKs, PI3K and JAK pathways were essential, whereas ERK1/2 appeared to play a direct role. S100A8 induction by CpG-DNA was controlled at the transcriptional level. The promoter region responsible for activation, either directly, or indirectly via IL-10 and PGE2, was located within a -178 to -34-bp region and required STAT3 binding. Because of the robust links connecting IL-10 and PGE2 with an anti-inflammatory macrophage phenotype, the induction profile of S100A8 strongly indicates a role for this protein in resolution of inflammation.