The murine IL-8 homologues KC, MIP-2, and LIX are found in endothelial cytoplasmic granules but not in Weibel-Palade bodies

Current Challenges to Align Inflammatory Key Events in Animals and Lung Cell Models In Vitro

With numerous novel and innovative in vitro models emerging every year to reduce or replace animal testing, there is an urgent need to align the design, harmonization, and validation of such systems using in vitro-in vivo extrapolation (IVIVE) approaches. In particular, in inhalation toxicology, there is a lack of predictive and prevalidated in vitro lung models that can be considered a valid alternative for animal testing. The predictive power of such models can be enhanced by applying the Adverse Outcome Pathways (AOP) framework, which casually links key events (KE) relevant to IVIVE. However, one of the difficulties identified is that the endpoint analysis and readouts of specific assays in in vitro and animal models for specific toxicants are currently not harmonized, making the alignment challenging. We summarize the current state of the art in endpoint analysis in the two systems, focusing on inflammatory-induced effects and providing guidance for future research directions to improve the alignment.

Chitosan siRNA Nanoparticles Produce Significant Non-Toxic Functional Gene Silencing in Kidney Cortices

Chitosan shows effective nucleic acid delivery. To understand the influence of chitosan's molecular weight, dose, payload, and hyaluronic acid coating on in vivo toxicity, immune stimulation, biodistribution and efficacy, precisely characterized chitosans were formulated with unmodified or chemically modified siRNA to control for innate immune stimulation. The hemocompatibility, cytokine induction, hematological and serological responses were assessed. Body weight, clinical signs, in vivo biodistribution and functional target knockdown were monitored. Hemolysis was found to be dose- and MW-dependent with the HA coating abrogating hemolysis. Compared to cationic lipid nanoparticles, uncoated and HA-coated chitosan nanoparticles did not induce immune stimulation or hematologic toxicity. Liver and kidney biomarkers remained unchanged with chitosan formulations, while high doses of cationic lipid nanoparticles led to increased transaminase levels and a decrease in body weight. Uncoated and HA-coated nanoparticles accumulated in kidneys with functional knockdown for uncoated chitosan formulations reaching 60%, suggesting potential applications in the treatment of kidney diseases.

Extracellular RNA Induces Neutrophil Recruitment Via Toll-Like Receptor 3 During Venous Thrombosis After Vascular Injury

BACKGROUND

Venous thromboembolism is associated with endothelial cell activation that contributes to the inflammation-dependent activation of the coagulation system. Cellular damage is associated with the release of different species of extracellular RNA (eRNA) involved in inflammation and coagulation. TLR3 (toll-like receptor 3), which recognizes (viral) single-stranded or double-stranded RNAs and self-RNA fragments, might be the receptor of these species of eRNA during venous thromboembolism. Here, we investigate how the TLR3/eRNA axis contributes to venous thromboembolism.

METHODS AND RESULTS

Thrombus formation and size in wild-type and TLR3 deficient (-/-) mice were monitored by ultrasonography after venous thrombosis induction using the ferric chloride and stasis models. Mice were treated with RNase I, with polyinosinic-polycytidylic acid, a TLR3 agonist, or with RNA extracted from murine endothelial cells. Gene expression and signaling pathway activation were analyzed in HEK293T cells overexpressing TLR3 in response to eRNA or in human umbilical vein endothelial cells transfected with a small interference RNA against TLR3. Plasma clot formation on treated human umbilical vein endothelial cells was analyzed. Thrombosis exacerbated eRNA release in vivo and increased eRNA content within the thrombus. RNase I treatment reduced thrombus size compared with vehicle-treated mice (P<0.05). Polyinosinic-polycytidylic acid and eRNA treatments increased thrombus size in wild-type mice (P<0.01 and P<0.05), but not in TLR3-/- mice, by reinforcing neutrophil recruitment (P<0.05). Mechanistically, TLR3 activation in endothelial cells promotes CXCL5 (C-X-C motif chemokine 5) secretion (P<0.001) and NFκB (nuclear factor kappa-light-chain-enhancer of activated B cells) activation (P<0.05). Finally, eRNA triggered plasma clot formation in vitro (P<0.01).

CONCLUSIONS

We show that eRNA and TLR3 activation enhance venous thromboembolism through neutrophil recruitment possibly through secretion of CXCL5, a potent neutrophil chemoattractant.

Alterations in gene expression and microbiome composition upon calcium-sensing receptor deletion in the mouse esophagus

The calcium-sensing receptor (CaSR), a G protein-coupled receptor, regulates Ca2+ concentration in plasma by regulating parathyroid hormone secretion. In other tissues, it is reported to play roles in cellular differentiation and migration and in secretion and absorption. We reported previously that CaSR can be conditionally deleted in the mouse esophagus. This conditional knockout (KO) (EsoCaSR-/-) model showed a significant reduction in the levels of adherens and tight junction proteins and had a marked buildup of bacteria on the luminal esophageal surface. To further examine the role of CaSR, we used RNA sequencing to determine gene expression profiles in esophageal epithelia of control and EsoCaSR-/-mice RNA Seq data indicated upregulation of gene sets involved in DNA replication and cell cycle in EsoCaSR-/-. This is accompanied by the downregulation of gene sets involved in the innate immune response and protein homeostasis including peptide elongation and protein trafficking. Ingenuity pathway analysis (IPA) demonstrated that these genes are mapped to important biological networks including calcium and Ras homologus A (RhoA) signaling pathways. To further explore the bacterial buildup in EsoCaSR-/- esophageal tissue, 16S sequencing of the mucosal-associated bacterial microbiome was performed. Three bacterial species, g_Rodentibacter, s_Rodentibacter_unclassified, and s_Lactobacillus_hilgardi were significantly increased in EsoCaSR-/-. Furthermore, metagenomic analysis of 16S sequences indicated that pathways related to oxidative phosphorylation and metabolism were downregulated in EsoCaSR-/- tissues. These data demonstrate that CaSR impacts major pathways of cell proliferation, differentiation, cell cycle, and innate immune response in esophageal epithelium. The disruption of these pathways causes inflammation and significant modifications of the microbiome.NEW & NOTEWORTHY Calcium-sensing receptor (CaSR) plays a significant role in maintaining the barrier function of esophageal epithelium. Using RNA sequencing, we show that conditional deletion of CaSR from mouse esophagus causes upregulation of genes involved in DNA replication and cell cycle and downregulation of genes involved in the innate immune response, protein translation, and cellular protein synthesis. Pathway analysis shows disruption of signaling pathways of calcium and actin cytoskeleton. These changes caused inflammation and esophageal dysbiosis.

Anti-Inflammatory Effects of Japanese Herbal Medicine Hochuekkito in a Mouse Model of Acute Exacerbation of Chronic Obstructive Pulmonary Disease

INTRODUCTION

The traditional Japanese herbal medicine hochuekkito (TJ-41) has been reported to ameliorate systemic inflammation and malnutrition in patients with chronic obstructive pulmonary disease (COPD). TJ-41 has also been known to have preventive effects against influenza virus infection. However, its role in the acute exacerbation of COPD (AECOPD) remains to be elucidated. Our previous study established a murine model of viral infection-associated AECOPD that was induced by intratracheal administration of porcine pancreatic elastase (PPE) and polyinosinic-polycytidylic acid [poly(I:C)]. Here, we used this model and investigated the effects of TJ-41 in AECOPD.

METHODS

Specific pathogen-free C57BL/6J mice were used. A COPD model was induced by treating mice intratracheally with PPE on day 0. To generate the murine model of AECOPD, poly(I:C) was administered intratracheally following PPE treatment on days 22-24. Mice were sacrificed and analyzed on day 25. Mice were fed a diet containing 2% TJ-41 or a control diet.

RESULTS

Daily oral intake of TJ-41 significantly decreased the numbers of neutrophils and lymphocytes in the bronchoalveolar lavage fluid (BALF), which was accompanied by decreased transcripts of CXC chemokines involved in neutrophil migration, viz., Cxcl1 and Cxcl2, in whole lung homogenates and reduced Cxcl2 concentration in BALF.

CONCLUSION

This study demonstrates the anti-inflammatory effects of TJ-41 in a mouse model of AECOPD, suggesting the effectiveness of TJ-41 for the management of COPD. Clinical investigations evaluating the therapeutic efficacy of TJ-41 in AECOPD would be meaningful.

The Annexin-A1 mimetic RTP-026 promotes acute cardioprotection through modulation of immune cell activation

AIMS

The cardio-protective and immuno-regulatory properties of RTP-026, a synthetic peptide that spans the Annexin-A1 (AnxA1) N-terminal region, were tested in rat acute myocardial infarction.

METHODS AND RESULTS

In vitro, selective activation of formyl-peptide receptor type 2 (FPR2) by RTP-026 occurred with apparent EC50 in the 10-30 nM range. With human primary cells, RTP-026 counteracted extension of neutrophil life-span and augmented phagocytosis of fluorescent E.coli by blood myeloid cells. An in vivo model of rat acute infarction was used to quantify tissue injury and phenotype immune cells in myocardium and blood. The rat left anterior descending coronary artery was occluded and then reopened for 2-hour or 24-hour reperfusion. For the 2-hour reperfusion protocol, RTP-026 (25-500 µg/kg; given i.v. at the start of reperfusion) significantly reduced infarct size by ∼50 %, with maximal efficacy at 50 µg/kg. Analyses of cardiac immune cells showed that RTP-026 reduced neutrophil and classical monocyte recruitment to the damaged heart. In the blood, RTP-026 (50 µg/kg) attenuated activation of neutrophils and monocytes monitored through CD62L and CD54 expression. Modulation of vascular inflammation by RTP-026 was demonstrated by reduction in plasma levels of mediators like TNF-α, IL-1β, KC, PGE2 and PGF2α⊡ For the 24-hour reperfusion protocol, RTP-026 (30 µg/kg given i.v. at 0, 3 and 6 h reperfusion) reduced necrotic myocardium by ∼40 %.

CONCLUSIONS

RTP-026 modulate immune cell responses and decreases infarct size of the heart in preclinical settings. Tempering over-exuberant immune cell activation by RTP-026 is a suitable approach to translate the biology of AnxA1 for therapeutic purposes.

Nonalcoholic steatohepatitis-associated hepatocarcinogenesis in mice fed a modified choline-deficient, methionine-lowered, L-amino acid-defined diet and the role of signal changes

Nonalcoholic steatohepatitis (NASH) can progress to cirrhosis and even hepatocellular carcinoma (HCC). The incidence of NASH-associated HCC is increasing, posing a serious public health threat. Unfortunately, the underlying pathological mechanisms, including the possible differences between neoplastic and non-neoplastic lesions, remain largely unknown. Previously, we reported a dietary mouse NASH model with a choline-deficient, methionine-lowered, L-amino-acid-defined, high-fat diet containing shortening without trans fatty acids (CDAA-HF-T[-]), which rapidly induces fibrosis and proliferative lesions in the liver. This study aimed to develop a mouse CDAA-HF-T(-) model capable of assessing NASH-associated hepatocarcinogenesis and identifying key signaling factors involved in its underlying mechanisms. Multiple large masses, histopathologically hepatocellular adenomas and carcinomas, and hemangiosarcomas were detected in the liver samples of mice fed CDAA-HF-T(-) for 52 or 63 weeks, along with highly advanced fibrosis and numerous foamy, phagocytic macrophages in the adjacent nontumoral area. Multiple metastatic nodules were found in the lungs of one of the animals, and lymphoid clusters were found in all CDAA-HF-T(-) group mice. In the Ingenuity Pathways Analysis of RNA expression data, the CDAA-HF-T(-) feeding revealed common signal changes in nontumoral and tumoral liver tissues, including increased IL-8 and RhoGTPases signaling and decreased lipid metabolism. Meanwhile, macrophage inflammatory protein 2 (MIP-2) expression levels were upregulated in nontumoral liver tissue from the end of Week 13 of CDAA-HF-T(-) feeding to the end of Week 63. On the other hand, MIP-2 was expressed on macrophages in non-tumor areas and hepatocytes in tumor areas. Therefore, the CDAA-HF-T(-) mouse model is useful for assessing NASH and NASH-associated hepatocarcinogenesis, and IL-8 signaling plays important roles in NASH-associated carcinogenesis and cirrhosis, but it may also play different roles in nontumoral liver tissue and tumorigenesis.

Tumour extracellular vesicles induce neutrophil extracellular traps to promote lymph node metastasis

Lymph nodes (LNs) are frequently the first sites of metastasis. Currently, the only prognostic LN assessment is determining metastatic status. However, there is evidence suggesting that LN metastasis is facilitated by the formation of a pre-metastatic niche induced by tumour derived extracellular vehicles (EVs). Therefore, it is important to detect and modify the LN environmental changes. Earlier work has demonstrated that neutrophil extracellular traps (NETs) can sequester and promote distant metastasis. Here, we first confirmed that LN NETs are associated with reduced patient survival. Next, we demonstrated that NETs deposition precedes LN metastasis and NETs inhibition diminishes LN metastases in animal models. Furthermore, we discovered that EVs are essential to the formation of LN NETs. Finally, we showed that lymphatic endothelial cells secrete CXCL8/2 in response to EVs inducing NETs formation and the promotion of LN metastasis. Our findings reveal the role of EV-induced NETs in LN metastasis and provide potential immunotherapeutic vulnerabilities that may occur early in the metastatic cascade.

Photoprotective and Anti-Aging Properties of the Apical Frond Extracts from the Mediterranean Seaweed Ericaria amentacea

There is a growing interest in using brown algal extracts thanks to the bioactive substances they produce for adaptation to the marine benthic environment. We evaluated the anti-aging and photoprotective properties of two types of extracts (50%-ethanol and DMSO) obtained from different portions, i.e., apices and thalli, of the brown seaweed, Ericaria amentacea. The apices of this alga, which grow and develop reproductive structures during summer when solar radiation is at its peak, were postulated to be rich in antioxidant compounds. We determined the chemical composition and pharmacological effects of their extracts and compared them to the thallus-derived extracts. All the extracts contained polyphenols, flavonoids and antioxidants and showed significant biological activities. The hydroalcoholic apices extracts demonstrated the highest pharmacological potential, likely due to the higher content of meroditerpene molecular species. They blocked toxicity in UV-exposed HaCaT keratinocytes and L929 fibroblasts and abated the oxidative stress and the production of pro-inflammatory cytokines, typically released after sunburns. Furthermore, the extracts showed anti-tyrosinase and anti-hydrolytic skin enzyme activity, counteracting the collagenase and hyaluronidase degrading activities and possibly slowing down the formation of uneven pigmentation and wrinkles in aging skin. In conclusion, the E. amentacea apices derivatives constitute ideal components for counteracting sunburn symptoms and for cosmetic anti-aging lotions.

Vascular cell-adhesion molecule 1 (VCAM-1) regulates JunB-mediated IL-8/CXCL1 expression and pathological neovascularization

Vascular adhesion molecules play an important role in various immunological disorders, particularly in cancers. However, little is known regarding the role of these adhesion molecules in proliferative retinopathies. We observed that IL-33 regulates VCAM-1 expression in human retinal endothelial cells and that genetic deletion of IL-33 reduces hypoxia-induced VCAM-1 expression and retinal neovascularization in C57BL/6 mice. We found that VCAM-1 via JunB regulates IL-8 promoter activity and expression in human retinal endothelial cells. In addition, our study outlines the regulatory role of VCAM-1-JunB-IL-8 signaling on retinal endothelial cell sprouting and angiogenesis. Our RNA sequencing results show an induced expression of CXCL1 (a murine functional homolog of IL-8) in the hypoxic retina, and intravitreal injection of VCAM-1 siRNA not only decreases hypoxia-induced VCAM-1-JunB-CXCL1 signaling but also reduces OIR-induced sprouting and retinal neovascularization. These findings suggest that VCAM-1-JunB-IL-8 signaling plays a crucial role in retinal neovascularization, and its antagonism might provide an advanced treatment option for proliferative retinopathies.

Effects of Glutamine, Curcumin and Fish Bioactive Peptides Alone or in Combination on Intestinal Permeability in a Chronic-Restraint Stress Model

Irritable bowel syndrome (IBS), a multifactorial intestinal disorder, is often associated with a disruption in intestinal permeability as well as an increased expression of pro-inflammatory markers. The aim of this study was to first test the impact of treatment with glutamine (Gln), a food supplement containing natural curcumin extracts and polyunsaturated n-3 fatty acids (Cur); bioactive peptides from a fish protein hydrolysate (Ga); and a probiotic mixture containing Bacillus coagulans, Lactobacillus acidophilus, Lactobacillus gasseri and Lactobacillus helveticus. These compounds were tested alone on a stress-based IBS model, the chronic-restraint stress model (CRS). The combination of Gln, Cur and Ga (GCG) was also tested. Eight-week-old C57Bl/6 male mice were exposed to restraint stress for two hours every day for four days and received different compounds every day one week before and during the CRS procedure. Plasma corticosterone levels were measured as a marker of stress, and colonic permeability was evaluated ex vivo in Ussing chambers. Changes in the gene expression of tight junction proteins (occludin, claudin-1 and ZO 1) and inflammatory cytokines (IL1β, TNFα, CXCL1 and IL10) were assessed using RT-qPCR. The CRS model led to an increase in plasma corticosterone and an increase in colonic permeability compared with unstressed animals. No change in plasma corticosterone concentrations was observed in response to CRS with the different treatments (Gln, Cur, Ga or GCG). Stressed animals treated with Gln, Cur and Ga alone and in combination showed a decrease in colonic permeability when compared to the CRS group, while the probiotic mixture resulted in an opposite response. The Ga treatment induced an increase in the expression of the anti-inflammatory cytokine IL-10, and the GCG treatment was able to decrease the expression of CXCL1, suggesting the synergistic effect of the combined mixture. In conclusion, this study demonstrated that a combined administration of glutamine, a food supplement containing curcumin and polyunsaturated n-3 fatty acids, and bioactive peptides from a fish hydrolysate was able to reduce colonic hyperpermeability and reduce the inflammatory marker CXCL1 in a stress-based model of IBS and could be of interest to patients suffering from IBS.

A potent and selective CXCR2 antagonist improves neuroimmune dysregulation through the inhibition of NF-κB and notch inflammatory signaling in the BTBR mouse model of autism

Autism comprises a broad range of neurodevelopmental disorders characterized by social communication deficits and repetitive and stereotyped behaviors. Chemokine receptor CXCR2 is expressed on neurons and is upregulated in neurological disorders. BTBR T+ Itpr3tf/J (BTBR) mice, a model for autism that shows the core features of ASD. Here, we studied the anti-inflammatory effect of a potent and selective CXCR2 antagonist SB332235 in the BTBR mice. The CXCR2 antagonist represents a promising therapeutic agent for several neuroinflammatory disorders. In this study, we investigated the effects of SB332235 administration on NF-κB-, Notch-1-, Notch-3-, GM-CSF-, MCP-1-, IL-6-, and IL-2- and TGF-β1-expressing CD40+ cells in BTBR and C57BL/6 (C57) mice in the spleen cells by flow cytometry. We further assessed the effect of SB332235 treatment on NF-κB, Notch-1, GM-CSF, MCP-1, IL-6, and IL-2 mRNA expression levels in the brain tissue by RT-PCR. We also explored the effect of SB332235 administration on NF-κB, GM-CSF, IL-6, and TGF-β1 protein expression levels in the brain tissue by western blotting. The SB332235-treated BTBR mice significantly decreases in CD40 + NF-κB+, CD40 + Notch-1+, CD40 + Notch-3+, CD40 + GM-CSF+, CD40 + MCP-1+, CD40 + IL-6+, and CD40 + IL-2+, and increases in CD40 + TGF-β1+ in the spleen cells. Our results further demonstrated that BTBR mice treated with SB332235 effectively decreased NF-κB, Notch-1, GM-CSF, MCP-1, IL-6, and IL-2, increasing TGF-β1 mRNA and protein expression levels in the brain tissue. In conclusion, these results indicate that SB332235 elicits an anti-inflammatory response by downregulating the inflammatory mediators and NF-κB/Notch inflammatory signaling in BTBR mice. This could represent a promising novel therapeutic target for autism treatment.

CXCR2 Antagonist RIST4721 Acts as a Potent Chemotaxis Inhibitor of Mature Neutrophils Derived from Ex Vivo-Cultured Mouse Bone Marrow

Neutrophils act as critical mediators of innate immunity, which depends on their rapid responses to chemokines followed by their migration towards sites of infection during chemotaxis. Chemokine receptors expressed on the surface of neutrophils mediate chemotaxis by activating contractile machinery as the cells escape from capillary beds and then attack pathogens. Neutrophils also contribute to inflammatory responses, which support pathogen destruction but can lead to acute and chronic inflammatory disorders. CXCR2, a G-protein-coupled chemokine receptor expressed on both myeloid and epithelial cells, is well-characterized for its capacities to bind multiple chemokines, including interleukin-8 and growth-related oncogene alpha in humans or keratinocyte chemokine (KC) in mice. Here we show that a small molecule CXCR2 antagonist termed RIST4721 can effectively inhibit KC-stimulated chemotaxis by neutrophils derived from ex vivo-cultured mouse bone marrow in a potent and dose-dependent manner. Antagonistic properties of RIST4721 are thoroughly characterized, including the maximal, half-maximal and minimum concentrations required to inhibit chemotaxis. Importantly, RIST4721-treated neutrophils exhibit robust phagocytosis and reactive oxygen species production, confirming drug specificity to chemotaxis inhibition. Together our data indicate that RIST4721 acts to inhibit inflammation mediated and potentiated by neutrophils and therefore promises to facilitate treatment of a host of inflammatory conditions.

Studies with neutralizing antibodies suggest CXCL8-mediated neutrophil activation is independent of C-C motif chemokine receptor-like 2 (CCRL2) ligand binding function

C-C motif chemokine receptor-like 2 (CCRL2) is a non-signaling 7 transmembrane receptor that binds chemotactic ligands to shape leukocyte recruitment to sites of inflammation. However, there is a lack of consensus on the ligands that directly bind CCRL2 or their functional impact. Studies with CCRL2 knockout mice have demonstrated that neutrophils have impaired degranulation and migration in response to CXCL8, where the underlying molecular mechanism is proposed to be due to the formation of CCRL2 heterodimers with the chemokine receptor CXCR2. Herein, we characterized the ligands that bind directly to CCRL2 and interrogated the impact of CCRL2 neutralization on CXCL8 signaling in neutrophils using pharmacological antibody tools. Using flow cytometry and Surface Plasmon Resonance microscopy (SPRm) cell binding experiments, we confirmed that chemerin, but not previously reported C-C chemokines, binds CCRL2. Furthermore, we identified human and mouse CCRL2 antibodies that neutralized chemerin binding to CCRL2. Unexpectedly, we found that neutralization of CCRL2 with these antibodies did not attenuate CXCL8-induced human neutrophil degranulation nor CXCL8-induced murine neutrophil recruitment to the peritoneum. Based on the observed differences in modulating CCRL2 function with neutralizing antibodies compared to the reported CCRL2 deficient murine models, we hypothesize that the ligand binding function of CCRL2 is dispensable for CXCL8 signaling in neutrophils. Finally, extensive profiling of CCRL2 expression on peripheral blood leukocytes revealed monocytes, dendritic cells (DC), and subpopulations of natural killer T (NKT) cells as additional targets, highlighting potential roles for CCRL2 in human cell types beyond neutrophils that warrants future investigation.

Pathogenesis of Anemia in Canine Babesiosis: Possible Contribution of Pro-Inflammatory Cytokines and Chemokines-A Review

Canine babesiosis is a tick-borne protozoan disease caused by intraerythrocytic parasites of the genus Babesia. The infection may lead to anemia in infected dogs. However, anemia is not directly caused by the pathogen. The parasite's developmental stages only have a marginal role in contributing to a decreased red blood cell (RBC) count. The main cause of anemia in affected dogs is the immune response to the infection. This response includes antibody production, erythrophagocytosis, oxidative damage of RBCs, complement activation, and antibody-dependent cellular cytotoxicity. Moreover, both infected and uninfected erythrocytes are retained in the spleen and sequestered in micro-vessels. All these actions are driven by pro-inflammatory cytokines and chemokines, especially IFN-γ, TNF-α, IL-6, and IL-8. Additionally, imbalance between the actions of pro- and anti-inflammatory cytokines plays a role in patho-mechanisms leading to anemia in canine babesiosis. This article is a review of the studies on the pathogenesis of anemia in canine babesiosis and related diseases, such as bovine or murine babesiosis and human or murine malaria, and the role of pro-inflammatory cytokines and chemokines in the mechanisms leading to anemia in infected dogs.

Nitration of chemokine CXCL8 acts as a natural mechanism to limit acute inflammation

Chemokine CXCL8 is a key facilitator of the human host immune response, mediating neutrophil migration, and activation at the site of infection and injury. The oxidative burst is an important effector mechanism which leads to the generation of reactive nitrogen species (RNS), including peroxynitrite. The current study was performed to determine the potential for nitration to alter the biological properties of CXCL8 and its detection in human disease. Here, we show peroxynitrite nitrates CXCL8 and thereby regulates neutrophil migration and activation. The nitrated chemokine was unable to induce transendothelial neutrophil migration in vitro and failed to promote leukocyte recruitment in vivo. This reduced activity is due to impairment in both G protein-coupled receptor signaling and glycosaminoglycan binding. Using a novel antibody, nitrated CXCL8 was detected in bronchoalveolar lavage samples from patients with pneumonia. These findings were validated by mass spectrometry. Our results provide the first direct evidence of chemokine nitration in human pathophysiology and suggest a natural mechanism that limits acute inflammation.

Neutrophil Heterogeneity and its Roles in the Inflammatory Network after Ischemic Stroke

As the first peripheral immune cells to enter the brain after ischemic stroke, neutrophils are important participants in stroke-related neuroinflammation. Neutrophils are quickly mobilized from the periphery in response to a stroke episode and cross the blood-brain barrier to reach the ischemic brain parenchyma. This process involves the mobilization and activation of neutrophils from peripheral immune organs (including the bone marrow and spleen), their chemotaxis in the peripheral blood, and their infiltration into the brain parenchyma (including disruption of the blood-brain barrier, inflammatory effects on brain tissue, and interactions with other immune cell types). In the past, it was believed that neutrophils aggravated brain injuries through the massive release of proteases, reactive oxygen species, pro-inflammatory factors, and extracellular structures known as neutrophil extracellular traps (NETs). With the failure of early clinical trials targeting neutrophils and uncovering their underlying heterogeneity, our view of their role in ischemic stroke has become more complex and multifaceted. As neutrophils can be divided into N1 and N2 phenotypes in tumors, neutrophils have also been found to have similar phenotypes after ischemic stroke, and play different roles in the development and prognosis of ischemic stroke. N1 neutrophils are dominant during the acute phase of stroke (within three days) and are responsible for the damage to neural structures via the aforementioned mechanisms. However, the proportion of N2 neutrophils gradually increases in later phases, and this has a beneficial effect through the release of anti-inflammatory factors and other neuroprotective mediators. Moreover, the N1 and N2 phenotypes are highly plastic and can be transformed into each other under certain conditions. The pronounced differences in their function and their high degree of plasticity make these neutrophil subpopulations promising targets for the treatment of ischemic stroke.

Thirty-five years since the discovery of chemotactic cytokines, interleukin-8 and MCAF: A historical overview

Inflammation is a host defense response to various invading stimuli, but an excessive and persistent inflammatory response can cause tissue injury, which can lead to irreversible organ damage and dysfunction. Excessive inflammatory responses are believed to link to most human diseases. A specific type of leukocyte infiltration into invaded tissues is required for inflammation. Historically, the underlying molecular mechanisms of this process during inflammation were an enigma, compromising research in the fields of inflammation, immunology, and pathology. However, the pioneering discovery of chemotactic cytokines (chemokines), monocyte-derived neutrophil chemotactic factor (MDNCF; interleukin [IL]-8, CXCL8) and monocyte chemotactic and activating factor (MCAF; monocyte chemotactic factor 1 [MCP-1], CCL2) in the late 1980s finally enabled us to address this issue. In this review, we provide a historical overview of chemokine research over the last 35 years.

PGF2α facilitates pathological retinal angiogenesis by modulating endothelial FOS-driven ELR+ CXC chemokine expression

The pathological retinal angiogenesis often causes blindness. Current anti-angiogenic therapy for proliferative retinopathy targets the vascular endothelial growth factor (VEGF), but many patients do not radically benefit from this therapy. Herein, we report that circulating prostaglandin (PG) F_2α metabolites were increased in type 2 diabetic patients with proliferative retinopathy, and the PGF_2α receptor (Ptgfr) was upregulated in retinal endothelial cells (ECs) from a mouse model of oxygen-induced retinopathy (OIR). Further, disruption of the PTGFR receptor in ECs attenuated OIR in mice. PGF_2α promoted the proliferation and tube formation of human retinal microvascular endothelial cells (HRMECs) via the release of ELR⁺ CXC chemokines, such as CXCL8 and CXCL2. Mechanistically, the PGF_2α /PTGFR axis potentiated ELR⁺ CXC chemokine expression in HRMECs through the G_q /CAMK2G/p38/ELK-1/FOS pathway. Upregulated FOS-mediated ELR⁺ CXC chemokine expression was observed in retinal ECs from PDR patients. Moreover, treatment with PTGFR inhibitor lessened the development of OIR in mice in a CXCR2-dependent manner. Therefore, inhibition of PTGFR may represent a new avenue for the treatment of retinal neovascularization, particularly in PDR.

Functional Blockage of S100A8/A9 Ameliorates Ischemia–Reperfusion Injury in the Lung

(1) Background: Lung ischemia–reperfusion (IR) injury increases the mortality and morbidity of patients undergoing lung transplantation. The objective of this study was to identify the key initiator of lung IR injury and to evaluate pharmacological therapeutic approaches using a functional inhibitor against the identified molecule. (2) Methods: Using a mouse hilar clamp model, the combination of RNA sequencing and histological investigations revealed that neutrophil-derived S100A8/A9 plays a central role in inflammatory reactions during lung IR injury. Mice were assigned to sham and IR groups with or without the injection of anti-S100A8/A9 neutralizing monoclonal antibody (mAb). (3) Results: Anti-S100A8/A9 mAb treatment significantly attenuated plasma S100A8/A9 levels compared with control IgG. As evaluated by oxygenation capacity and neutrophil infiltration, the antibody treatment dramatically ameliorated the IR injury. The gene expression levels of cytokines and chemokines induced by IR injury were significantly reduced by the neutralizing antibody. Furthermore, the antibody treatment significantly reduced TUNEL-positive cells, indicating the presence of apoptotic cells. (4) Conclusions: We identified S100A8/A9 as a novel therapeutic target against lung IR injury.

Targeting tumour-intrinsic N7-methylguanosine tRNA modification inhibits MDSC recruitment and improves anti-PD-1 efficacy

OBJECTIVE

Intrahepatic cholangiocarcinoma (ICC) exhibits very low response rate to immune checkpoint inhibitors (ICIs) and the underlying mechanism is largely unknown. We investigate the tumour immune microenvironment (TIME) of ICCs and the underlying regulatory mechanisms with the aim of developing new target to inhibit tumour growth and improve anti-programmed cell death protein-1 (PD-1) efficacy.

DESIGN

Tumour tissues from patients with ICC together with hydrodynamic ICC mouse models were employed to identify the key cell population in TIME of ICCs. Functional analysis and mechanism studies were performed using cell culture, conditional knockout mouse model and hydrodynamic transfection ICC model. The efficacy of single or combined therapy with anti-PD-1 antibody, gene knockout and chemical inhibitor were evaluated in vivo.

RESULTS

Polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) are enriched in advanced ICCs and significantly correlated with N⁷-methylguanosine tRNA methyltransferase METTL1. Using diverse in vivo cancer models, we demonstrate the crucial immunomodulator function of METTL1 in regulation of PMN-MDSC accumulation in TIME and ICC progression. Mechanistically, CXCL8 in human and Cxcl5 in mouse are key translational targets of METTL1 that facilitate its function in promoting PMN-MDSC accumulation in TIME and ICC progression in vivo. Co-blockade of METTL1 and its downstream chemokine pathway enhances the anti-PD-1 efficacy in ICC preclinical mouse models.

CONCLUSIONS

Our data uncover novel mechanisms underlying chemokine regulation and TIME shaping at the layer of messenger RNA translation level and provide new insights for development of efficient cancer immunotherapeutic strategies.

CXC Chemokines in the Pathogenesis of Pulmonary Disease and Pharmacological Relevance

Chemokines and their receptors play important roles in the pathophysiology of many diseases by regulating the cellular migration of major inflammatory and immune players. The CXC motif chemokine subfamily is the second largest family, and it is further subdivided into ELR motif CXC (ELR+) and non-ELR motif (ELR-) CXC chemokines, which are effective chemoattractants for neutrophils and lymphocytes/monocytes, respectively. These chemokines and their receptors are expected to have a significant impact on a wide range of lung diseases, many of which have inflammatory or immunological underpinnings. As a result, manipulations of this subfamily of chemokines and their receptors using small molecular agents and other means have been explored for potential therapeutic benefit in the setting of several lung pathologies. Furthermore, encouraging preclinical data has necessitated the progression of a few of these drugs into clinical trials in order to make the most effective use of interventions in the development of viable targeted therapeutics. The current review presents the understanding of the roles of CXC ligands (CXCLs) and their cognate receptors (CXCRs) in the pathogenesis of several lung diseases such as allergic rhinitis, COPD, lung fibrosis, lung cancer, pneumonia, and tuberculosis. The potential therapeutic benefits of pharmacological or other CXCL/CXCR axis manipulations are also discussed.

Anti-Inflammatory Effects of Cicadidae Periostracum Extract and Oleic Acid through Inhibiting Inflammatory Chemokines Using PCR Arrays in LPS-Induced Lung inflammation In Vitro

In this study, we aimed to evaluate the anti-inflammatory effects and mechanisms of CP and OA treatments in LPS-stimulated lung epithelial cells on overall chemokines and their receptors using PCR arrays. In addition, we aimed to confirm those effects and mechanisms in LPS-stimulated lung macrophages on some chemokines and cytokines. In our study, CP treatments significantly inhibited the inflammatory mediators CCL2, CCL3, CCL4, CCL5, CCL6, CCL9, CCL11, CCL17, CCL20, CXCL1, CXCL2, CXCL3, CXCL5, CXCL7, CXCL10, TNF-α, and IL-6, while markedly suppressing NF-κB p65 nuclear translocation and the phosphorylations of PI3K p55, Akt, Erk1/2, p38, and NF-κB p65 in LPS-stimulated lung epithelial cells. CP treatments also significantly decreased the inflammatory mediators CCL2, CCL5, CCL17, CXCL1, and CXCL2, while markedly inhibiting phospho-PI3K p55 and iNOS expression in LPS-stimulated lung macrophages. Likewise, OA treatments significantly suppressed the inflammatory mediators CCL2, CCL3, CCL4, CCL5, CCL8, CCL11, CXCL1, CXCL3, CXCL5, CXCL7, CXCL10, CCRL2, TNF-α, and IL-6, while markedly reducing the phosphorylations of PI3K p85, PI3K p55, p38, JNK, and NF-κB p65 in LPS-stimulated lung epithelial cells. Finally, OA treatments significantly inhibited the inflammatory mediators CCL2, CCL5, CCL17, CXCL1, CXCL2, TNF-α, and IL-6, while markedly suppressing phospho-PI3K p55, iNOS, and Cox-2 in LPS-stimulated lung macrophages. These results prove that CP and OA treatments have anti-inflammatory effects on the inflammatory chemokines and cytokines by inhibiting pro-inflammatory mediators, including PI3K, Akt, MAPKs, NF-κB, iNOS, and Cox-2. These findings suggest that CP and OA are potential chemokine-based therapeutic substances for treating the lung and airway inflammation seen in allergic disorders.

Differential Regulation of Allergic Airway Inflammation by Acetylcholine

Acetylcholine (ACh) from neuronal and non-neuronal sources plays an important role in the regulation of immune responses and is associated with the development of several disease pathologies. We have previously demonstrated that group 2 innate lymphoid cell (ILC2)-derived ACh is required for optimal type 2 responses to parasitic infection and therefore sought to determine whether this also plays a role in allergic inflammation. Rora^Cre+Chat^LoxP mice (in which ILC2s cannot synthesize ACh) were exposed to an allergenic extract of the fungus Alternaria alternata, and immune responses in the airways and lung tissues were analyzed. Airway neutrophilia and expression of the neutrophil chemoattractants CXCL1 and CXCL2 were enhanced 24 h after exposure, suggesting that ILC2-derived ACh plays a role in limiting excessive pulmonary neutrophilic inflammation. The effect of non-selective depletion of ACh was examined by intranasal administration of a stable parasite-secreted acetylcholinesterase. Depletion of airway ACh in this manner resulted in a more profound enhancement of neutrophilia and chemokine expression, suggesting multiple cellular sources for the release of ACh. In contrast, depletion of ACh inhibited Alternaria-induced activation of ILC2s, suppressing the expression of IL-5, IL-13, and subsequent eosinophilia. Depletion of ACh reduced macrophages with an alternatively activated M2 phenotype and an increase in M1 macrophage marker expression. These data suggest that ACh regulates allergic airway inflammation in several ways, enhancing ILC2-driven eosinophilia but suppressing neutrophilia through reduced chemokine expression.

Lipopolysaccharide from the Cyanobacterium Geitlerinema sp. Induces Neutrophil Infiltration and Lung Inflammation

Glucocorticoid-resistant asthma, which predominates with neutrophils instead of eosinophils, is an increasing health concern. One potential source for the induction of neutrophil-predominant asthma is aerosolized lipopolysaccharide (LPS). Cyanobacteria have recently caused significant tidal blooms, and aerosolized cyanobacterial LPS has been detected near the cyanobacterial overgrowth. We hypothesized that cyanobacterial LPS contributes to lung inflammation by increasing factors that promote lung inflammation and neutrophil recruitment. To test this hypothesis, c57Bl/6 mice were exposed intranasally to LPS from the cyanobacterium member, Geitlerinema sp., in vivo to assess neutrophil infiltration and the production of pro-inflammatory cytokines and chemokines from the bronchoalveolar fluid by ELISA. Additionally, we exposed the airway epithelial cell line, A549, to Geitlerinema sp. LPS in vitro to confirm that airway epithelial cells were stimulated by this LPS to increase cytokine production and the expression of the adhesion molecule, ICAM-1. Our data demonstrate that Geitlerinema sp. LPS induces lung neutrophil infiltration, the production of pro-inflammatory cytokines such as Interleukin (IL)-6, Tumor necrosis factor-alpha, and Interferongamma as well as the chemokines IL-8 and RANTES. Additionally, we demonstrate that Geitlerinema sp. LPS directly activates airway epithelial cells to produce pro-inflammatory cytokines and the adhesion molecule, Intercellular Adhesion Molecule-1 (ICAM-1), in vitro using the airway epithelial cell line, A549. Based on our findings that use Geitlerinema sp. LPS as a model system, the data indicate that cyanobacteria LPS may contribute to the development of glucocorticoid-resistant asthma seen near water sources that contain high levels of cyanobacteria.

ALKBH5 Facilitates Hypoxia-Induced Paraspeckle Assembly and IL8 Secretion to Generate an Immunosuppressive Tumor Microenvironment

The dynamic changes of RNA N6-methyl-adenosine (m⁶A) during cancer progression contribute to quick adaption to microenvironmental changes. Here, we profiled the cancer cell m⁶A dynamics in the hypoxic tumor niche and its pathological consequences in glioblastoma multiforme (GBM). The m⁶A demethylase ALKBH5 was induced in GBM models under hypoxic conditions and was associated with a hypoxic gene signature in GBM patient samples. Depletion or inactivation of ALKBH5 in GBM cells significantly suppressed hypoxia-induced tumor-associated macrophage (TAM) recruitment and immunosuppression in allograft tumors. Expression and secretion of CXCL8/IL8 were significantly suppressed in ALKBH5-deficient tumors. However, ALKBH5 did not regulate CXCL8 m⁶A directly. Instead, hypoxia-induced ALKBH5 erased m⁶A deposition from the lncRNA NEAT1, stabilizing the transcript and facilitating NEAT1-mediated paraspeckle assembly, which led to relocation of the transcriptional repressor SFPQ from the CXCL8 promoter to paraspeckles and, ultimately, upregulation of CXCL8/IL8 expression. Accordingly, ectopic expression of CXCL8 in ALKBH5-deficient GBM cells partially restored TAM recruitment and tumor progression. Together, this study links hypoxia-induced epitranscriptomic changes to the emergence of an immunosuppressive microenvironment facilitating tumor evasion. SIGNIFICANCE: Hypoxia induces tumor immune microenvironment remodeling through an ALKBH5-mediated epigenetic and epitranscriptomic mechanism, providing potential immunotherapeutic strategies for treating glioblastoma.

Guidelines for the use of flow cytometry and cell sorting in immunological studies (third edition)

The third edition of Flow Cytometry Guidelines provides the key aspects to consider when performing flow cytometry experiments and includes comprehensive sections describing phenotypes and functional assays of all major human and murine immune cell subsets. Notably, the Guidelines contain helpful tables highlighting phenotypes and key differences between human and murine cells. Another useful feature of this edition is the flow cytometry analysis of clinical samples with examples of flow cytometry applications in the context of autoimmune diseases, cancers as well as acute and chronic infectious diseases. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid. All sections are written and peer-reviewed by leading flow cytometry experts and immunologists, making this edition an essential and state-of-the-art handbook for basic and clinical researchers.

Small Extracellular Vesicles Propagate the Inflammatory Response After Trauma

Trauma is the leading cause of death in individuals under 44 years of age. Thorax trauma (TxT) is strongly associated with trauma-related death, an unbalanced innate immune response, sepsis, acute respiratory distress syndrome, and multiple organ dysfunction. It is shown that different in vivo traumata, such as TxT or an in vitro polytrauma cytokine cocktail trigger secretion of small extracellular nanovesicles (sEVs) from endothelial cells with pro-inflammatory cargo. These sEVs transfer transcripts for ICAM-1, VCAM-1, E-selectin, and cytokines to systemically activate the endothelium, facilitate neutrophil-endothelium interactions, and destabilize barrier integrity. Inhibition of sEV-release after TxT in mice ameliorates local as well as systemic inflammation, neutrophil infiltration, and distant organ damage in kidneys (acute kidney injury, AKI). Vice versa, injection of TxT-plasma-sEVs into healthy animals is sufficient to trigger pulmonary and systemic inflammation as well as AKI. Accordingly, increased sEV concentrations and transfer of similar cargos are observed in polytrauma patients, suggesting a fundamental pathophysiological mechanism.

Natural Compound Resveratrol Attenuates TNF-Alpha-Induced Vascular Dysfunction in Mice and Human Endothelial Cells: The Involvement of the NF-κB Signaling Pathway

Resveratrol, a natural compound in grapes and red wine, has drawn attention due to potential cardiovascular-related health benefits. However, its effect on vascular inflammation at physiologically achievable concentrations is largely unknown. In this study, resveratrol in concentrations as low as 1 μm suppressed TNF-α-induced monocyte adhesion to human EA.hy926 endothelial cells (ECs), a key event in the initiation and development of atherosclerosis. Low concentrations of resveratrol (0.25–2 μm) also significantly attenuated TNF-α-stimulated mRNA expressions of MCP-1/CCL2 and ICAM-1, which are vital mediators of EC-monocyte adhesion molecules and cytokines for cardiovascular plaque formation. Additionally, resveratrol diminished TNF-α-induced IκB-α degradation and subsequent nuclear translocation of NF-κB p65 in ECs. In the animal study, resveratrol supplementation in diet significantly diminished TNF-α-induced increases in circulating levels of adhesion molecules and cytokines, monocyte adhesion to mouse aortic ECs, F4/80-positive macrophages and VCAM-1 expression in mice aortas and restored the disruption in aortic elastin fiber caused by TNF-α treatment. The animal study also confirmed that resveratrol blocks the activation of NF-κB In Vivo. In conclusion, resveratrol at physiologically achievable concentrations displayed protective effects against TNF-α-induced vascular endothelial inflammation in vitro and In Vivo. The ability of resveratrol in reducing inflammation may be associated with its role as a down-regulator of the NF-κB pathway.

Cytokine and Complement Response in the Glaucomatous βB1-CTGF Mouse Model

Glaucoma is a complex neurodegenerative disease leading to a loss of retinal ganglion cells (RGCs) and optic nerve axons. An activation of the complement system seems to contribute to cell loss in this disease. Hence, we investigated a possible initiation of the complement system and the cytokine response in the βB1-CTGF glaucoma model. In these mice, intraocular pressure is elevated, which is the main glaucoma risk factor in patients, and RGC loss occurs at 15 weeks of age. Therefore, quantitative real-time PCR and immunohistological experiments were performed in 5-, 10-, and 15-week-old βB1-CTGF animals and their corresponding wildtypes (WT) to analyze the expression of several complement system factors. We could show that mRNA levels of the terminal complement pathway components C3 and C5 (Hc) were upregulated at 10 weeks. In accordance, more C3+ and membrane attack complex+ cells were observed in transgenic retinae. Further, the C5a receptor anaphylatoxin receptor (C5ar) and the complement component C5a receptor 1 (C5ar1; CD88) mRNA levels were upregulated in 10- and 15-week-old βB1-CTGF mice. Interestingly, all three activation routes of the complement system were elevated in βB1-CTGF mice at some age. Especially C1q, as a marker of the classical pathway, was significantly increased at all investigated ages. Furthermore, mRNA expression levels of interferon-γ (Infg) were upregulated at 5 weeks, while Cxcl1 and Cxcl2 mRNA levels were upregulated at 10 and 15 weeks. The mRNA levels of the chemokines Cxcl10 were increased at all ages in βB1-CTGF mice. These results lead to the assumption that in these transgenic mice, a complement activation mainly through the classical pathway as well as a cytokine response plays a major role in cell death.

Group-2 Innate Lymphoid Cells Promote HCC Progression Through CXCL2-Neutrophil-Induced Immunosuppression

BACKGROUND AND AIMS

Due to their inherent characteristics, the function of group-2 innate lymphoid cells (ILC2s) varies in a context-dependent manner. ILC2s are involved in certain liver diseases; however, their involvement in HCC is unknown. In the present study, we assessed the role of an HCC-derived ILC2 population in tumor progression.

APPROACH AND RESULTS

Through FACS and single-cell RNA sequencing, we discovered that ILC2s were highly enriched in human HCC and correlated significantly with tumor recurrence and worse progression-free survival as well as overall survival in patients. Mass cytometry identified a subset of HCC-derived ILC2s that had lost the expression of killer cell lectin-like receptor subfamily G, member 1 (KLRG1). Distinct from their circulating counterparts, these hepatic ILC2s highly expressed CD69 and an array of tissue resident-related genes. Furthermore, reduction of E-cadherin in tumor cells caused the loss of KLRG1 expression in ILC2s, leading to their increased proliferation and subsequent accumulation in HCC sites. The KLRG1^- ILC2 subset showed elevated production of chemotaxis factors, including C-X-C motif chemokine (C-X-C motif) ligand (CXCL)-2 and CXCL8, which in turn recruited neutrophils to form an immunosuppressive microenvironment, leading to tumor progression. Accordingly, restoring KLRG1 in ILC2s, inhibiting CXCL2 in ILC2s, or depleting neutrophils inhibited tumor progression in a murine HCC model.

CONCLUSIONS

We identified HCC-associated ILC2s as an immune regulatory cell type that promotes tumor development, suggesting that targeting these ILC2s might lead to new treatments for HCC.

Neutrophil-mediated clinical nanodrug for treatment of residual tumor after focused ultrasound ablation

Background

The risk of local recurrence after high-intensity focused ultrasound (HIFU) is relatively high, resulting in poor prognosis of malignant tumors. The combination of HIFU with traditional chemotherapy continues to have an unsatisfactory outcome because of off-site drug uptake.

Results

Herein, we propose a strategy of inflammation-tendency neutrophil-mediated clinical nanodrug targeted therapy for residual tumors after HIFU ablation. We selected neutrophils as carriers and PEGylated liposome doxorubicin (PLD) as a model chemotherapeutic nanodrug to form an innovative cell therapy drug (PLD@NEs). The produced PLD@NEs had a loading capacity of approximately 5 µg of PLD per 10⁶ cells and maintained the natural characteristics of neutrophils. The targeting performance and therapeutic potential of PLD@NEs were evaluated using Hepa1-6 cells and a corresponding tumor-bearing mouse model. After HIFU ablation, PLD@NEs were recruited to the tumor site by inflammation (most in 4 h) and released PLD with inflammatory stimuli, leading to targeted and localized postoperative chemotherapy.

Conclusions

This effective integrated method fully leverages the advantages of HIFU, chemotherapy and neutrophils to attract more focus on the practice of improving existing clinical therapies.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01087-w.

Tumor-Associated Microglia/Macrophages as a Predictor for Survival in Glioblastoma and Temozolomide-Induced Changes in CXCR2 Signaling with New Resistance Overcoming Strategy by Combination Therapy

Tumor recurrence is the main challenge in glioblastoma (GBM) treatment. Gold standard therapy temozolomide (TMZ) is known to induce upregulation of IL8/CXCL2/CXCR2 signaling that promotes tumor progression and angiogenesis. Our aim was to verify the alterations on this signaling pathway in human GBM recurrence and to investigate the impact of TMZ in particular. Furthermore, a combi-therapy of TMZ and CXCR2 antagonization was established to assess the efficacy and tolerability. First, we analyzed 76 matched primary and recurrent GBM samples with regard to various histological aspects with a focus on the role of TMZ treatment and the assessment of predictors of overall survival (OS). Second, the combi-therapy with TMZ and CXCR2-antagonization was evaluated in a syngeneic mouse tumor model with in-depth immunohistological investigations and subsequent gene expression analyses. We observed a significantly decreased infiltration of tumor-associated microglia/macrophages (TAM) in recurrent tumors, while a high TAM infiltration in primary tumors was associated with a reduced OS. Additionally, more patients expressed IL8 in recurrent tumors and TMZ therapy maintained CXCL2 expression. In mice, enhanced anti-tumoral effects were observed after combi-therapy. In conclusion, high TAM infiltration predicts a survival disadvantage, supporting findings of the tumor-promoting phenotype of TAMs. Furthermore, the combination therapy seemed to be promising to overcome CXCR2-mediated resistance.

CCL11 exacerbates colitis and inflammation-associated colon tumorigenesis

CCL11, also known as eotaxin-1, is described as an eosinophil chemoattractant, which has been implicated in allergic and Th2 inflammatory diseases. We have reported that CCL11 is significantly increased in the serum of inflammatory bowel disease (IBD) patients, colonic eosinophils are increased and correlate with tissue CCL11 levels in ulcerative colitis patients, and CCL11 is increased in dextran sulfate sodium (DSS)-induced murine colitis. Here, we show that CCL11 is involved in the pathogenesis of DSS-induced colitis and in colon tumorigenesis in the azoxymethane (AOM)-DSS model of colitis-associated carcinogenesis (CAC). Ccl11^-/- mice exposed to DSS then allowed to recover had significantly less body weight loss and a decrease in histologic injury versus wild-type (WT) mice. In the AOM-DSS model, Ccl11^-/- mice exhibited decreased colonic tumor number and burden, histologic injury, and colonic eosinophil infiltration versus WT mice. Ccl11 is expressed by both colonic epithelial and lamina propria immune cells. Studies in bone marrow chimera mice revealed that hematopoietic- and epithelial-cell-derived CCL11 were both important for tumorigenesis in the AOM-DSS model. These findings indicate that CCL11 is important in the regulation of colitis and associated carcinogenesis and thus anti-CCL11 antibodies may be useful for treatment and cancer chemoprevention in IBD.

Inducible Sbds Deletion Impairs Bone Marrow Niche Capacity to Engraft Donor Bone Marrow After Transplantation

Bone marrow (BM) niche-derived signals are critical for facilitating engraftment after hematopoietic stem cell (HSC) transplantation (HSCT). HSCT is required for restoration of hematopoiesis in patients with inherited bone marrow failure syndromes (iBMFS). Shwachman-Diamond syndrome (SDS) is a rare iBMFS associated with mutations in SBDS. Previous studies have demonstrated that SBDS deficiency in osteolineage niche cells causes bone marrow dysfunction that promotes leukemia development. However, it is unknown whether BM niche defects caused by SBDS deficiency also impair efficient engraftment of healthy donor HSC following HSCT, a hypothesis that could explain morbidity seen after clinical HSCT for patients with SDS. Here, we report a mouse model with inducible Sbds deletion in hematopoietic and osteolineage cells. Primary and secondary BM transplantation (BMT) studies demonstrated that SBDS deficiency within BM niches caused poor donor hematopoietic recovery and specifically poor HSC engraftment after myeloablative BMT. We have additionally identified multiple molecular and cellular defects within niche populations that are driven by SBDS deficiency and that are accentuated or develop specifically following myeloablative conditioning. These abnormalities include altered frequencies of multiple niche cell subsets including mesenchymal lineage cells, macrophages and endothelial cells; disruption of growth factor signaling, chemokine pathway activation, and adhesion molecule expression; and p53 pathway activation, and signals involved in cell cycle arrest. Taken together, this study demonstrates that SBDS deficiency profoundly impacts recipient hematopoietic niche function in the setting of HSCT, suggesting that novel therapeutic strategies targeting host niches could improve clinical HSCT outcomes for patients with SDS.

High-Fat Diet-Induced Obese Effects of Adipocyte-Specific CXCR2 Conditional Knockout in the Peritoneal Tumor Microenvironment of Ovarian Cancer

Obesity contributes to ovarian cancer (OC) progression via tumorigenic chemokines. Adipocytes and OC cells highly express CXCR2, and its ligands CXCL1/8, respectively, indicating that the CXCL1/8-CXCR2 axis is a molecular link between obesity and OC. Here, we investigated how the adipocyte-specific CXCR2 conditional knockout (cKO) affected the peritoneal tumor microenvironment of OC in a high-fat diet (HFD)-induced obese mouse model. We first generated adipocyte-specific CXCR2 cKO in mice: adipose tissues were not different in crown-like structures and adipocyte size between the wild-type (WT) and cKO mice but expressed lower levels of CCL2/6 compared to the obese WT mice. HFD-induced obese mice had a shorter survival time than lean mice. Particularly, obese WT and cKO mice developed higher tumors and ascites burdens, respectively. The ascites from the obese cKO mice showed increased vacuole clumps but decreased the floating tumor burden, tumor-attached macrophages, triglyceride, free fatty acid, CCL2, and TNF levels compared to obese WT mice. A tumor analysis revealed that obese cKO mice attenuated inflammatory areas, PCNA, and F4/80 compared to obese WT mice, indicating a reduced tumor burden, and there were positive relationships between the ascites and tumor parameters. Taken together, the adipocyte-specific CXCR2 cKO was associated with obesity-induced ascites despite a reduced tumor burden, likely altering the peritoneal tumor microenvironment of OC.

Human Milk Oligosaccharide 3'-GL Improves Influenza-Specific Vaccination Responsiveness and Immunity after Deoxynivalenol Exposure in Preclinical Models

Deoxynivalenol (DON), a highly prevalent mycotoxin food contaminant, is known to have immunotoxic effects. In the current study, the potential of dietary interventions with specific mixtures of trans-galactosyl-oligosaccharides (TOS) to alleviate these effects were assessed in a murine influenza vaccination model. Vaccine-specific immune responses were measured in C57Bl/6JOlaHsd mice fed diets containing DON, TOS or a combination, starting 2 weeks before the first vaccination. The direct effects of TOS and its main oligosaccharide, 3'-galactosyl-lactose (3'-GL), on DON-induced damage were studied in Caco-2 cells, as an in vitro model of the intestinal epithelial barrier. Exposure to DON significantly reduced vaccine-specific immune responses and the percentages of Tbet+ Th1 cells and B cells in the spleen. DON significantly altered epithelial structure and integrity in the ileum and reduced the SCFA levels in the cecum. Adding TOS into DON-containing diets significantly improved vaccine-specific immune responses, restored the immune cell balance in the spleen and increased SCFA concentrations in the cecum. Incubating Caco-2 cells with TOS and 3'-GL in vitro further confirmed their protective effects against DON-induced barrier disruption, supporting immune modulation. Overall, dietary intervention with TOS can attenuate the adverse effects of DON on Th1-mediated immune responses and gut homeostasis. These beneficial properties might be linked to the high levels of 3'-GL in TOS.

Super enhancer regulation of cytokine-induced chemokine production in alcoholic hepatitis

Alcoholic hepatitis (AH) is associated with liver neutrophil infiltration through activated cytokine pathways leading to elevated chemokine expression. Super-enhancers are expansive regulatory elements driving augmented gene expression. Here, we explore the mechanistic role of super-enhancers linking cytokine TNFα with chemokine amplification in AH. RNA-seq and histone modification ChIP-seq of human liver explants show upregulation of multiple CXCL chemokines in AH. Liver sinusoidal endothelial cells (LSEC) are identified as an important source of CXCL expression in human liver, regulated by TNFα/NF-κB signaling. A super-enhancer is identified for multiple CXCL genes by multiple approaches. dCas9-KRAB-mediated epigenome editing or pharmacologic inhibition of Bromodomain and Extraterminal (BET) proteins, transcriptional regulators vital to super-enhancer function, decreases chemokine expression in vitro and decreases neutrophil infiltration in murine models of AH. Our findings highlight the role of super-enhancer in propagating inflammatory signaling by inducing chemokine expression and the therapeutic potential of BET inhibition in AH treatment.

Design and Evaluation of an In Vitro Mild Traumatic Brain Injury Modeling System Using 3D Printed Mini Impact Device on the 3D Cultured Human iPSC Derived Neural Progenitor Cells

Despite significant progress in understanding the disease mechanism of traumatic brain injury (TBI), promising preclinical therapeutics have seldom been translated into successful clinical outcomes, partially because the model animals have physiological and functional differences in the central nervous system (CNS) compared to humans. Human relevant models are thus urgently required. Here, an in vitro mild TBI (mTBI) modeling system is reported based on 3D cultured human induced pluripotent stem cells (iPSC) derived neural progenitor cells (iPSC-NPCs) to evaluate consequences of single and repetitive mTBI using a 3D printed mini weight-drop impact device. Computational simulation is performed to understand the single/cumulative effects of weight-drop impact on the NPC differentiated neurospheres. Experimental results reveal that neurospheres show reactive astrogliosis and glial scar formation after repetitive (10 hits) mild impacts, while no astrocyte activation is found after one or two mild impacts. A 3D co-culture model of human microglia cells with neurospheres is further developed. It is found that astrocyte response is promoted even after two mild impacts, possibly caused by the chronic neuroinflammation after microglia activation. The in vitro mTBI modeling system recapitulates several hallmarks of the brain impact injury and might serve as a good platform for future drug screening.

Identification of the dominant angiogenic CXCL class chemokines associated with non-small cell lung cancer via bioinformatics tools

Chemokines play a critical role in lung cancer progression and metastasis. In non-small cell lung cancer, the determination of dominant angiogenic CXCL-type chemokines may increase the efficacy of targeted therapy and modulate the prognosis of lung cancer. Also, chemokine and chemokine receptors shape the immune response in the cross-talk between both cancer cells and immune cells in the tumor microenvironment. In this computational evaluation study based on databases containing mostly RNA-seq analyses, it is aimed to determine the dominant angiogenic CXCL-type chemokines with the highest expression in lung adenocarcinoma tissues and particularly in non-small cell lung cancer cells. CXCL1, CXCL5, CXCL7, and CXCL8, which can potentially be co-regulated and associated with poor survival, and phagocyte infiltration including neutrophils and macrophages are predominantly identified in non-small cell lung cancer. Moreover, the receptors of these chemokines, CXCR1 (binding CXCL8) and CXCR2 (binding CXCL1, 5, 7, 8), are positively correlated with the infiltration of neutrophils and macrophages. With the discovery of the common regulatory mechanisms of these angiogenic chemokines and validation studies in clinical examples, the chemokine panels specific to non-small cell lung cancer will become clear and have a decisive role in the prognosis of the disease.

Viral infection and allergy - What equine immune responses can tell us about disease severity and protection

Horses have many naturally occurring diseases that mimic similar conditions in humans. The ability to conduct environmentally controlled experiments and induced disease studies in a genetically diverse host makes the horse a valuable intermediate model between mouse studies and human clinical trials. This review highlights important similarities in the immune landscape between horses and humans using current research on two equine diseases as examples. First, equine herpesvirus type 1 (EHV-1) infection initiates a series of innate inflammatory signals at its mucosal entry site in the upper respiratory tract. These inflammatory markers are highly synchronized and predictable between individuals during viral respiratory infection and ultimately lead to adaptive immune induction and protection. The timing of early inflammatory signals, followed by specific adaptive immune markers correlating with immunity and protection, allow accurate outbreak tracking and also provide a foundation for understanding the importance of local mucosal immunity during other viral respiratory infections. Second, rare peripheral blood immune cells that promote allergic inflammation can be analyzed during Culicoides hypersensitivity, a naturally occurring type I IgE-mediated allergic disease of horses. Rare immune cells, such as IgE-binding monocytes or basophils, can be studied repeatedly in the horse model to unravel their larger mechanistic role in inflammation during allergic and other inflammatory diseases. We conclude with a survey of all other common equine inflammatory conditions. Together, this review serves as a reference and rationale for the horse as a non-rodent model for immunological research.

IgE-Binding Monocytes Have an Enhanced Ability to Produce IL-8 (CXCL8) in Animals with Naturally Occurring Allergy

IL-8 is a potent chemokine that recruits neutrophils and basophils to promote inflammation in many species. IL-8 is produced by many cell types, including monocytes. In this study, we report a novel role for IgE-binding monocytes, a rare peripheral immune cell type, to promote allergic inflammation through IL-8 production in a horse model of natural IgE-mediated allergy. We developed a mAb with confirmed specificity for both recombinant and native equine IL-8 for flow cytometric analysis. Equine IL-8 was produced by CD14⁺/MHC class II⁺/CD16^- monocytes, including a subpopulation of IgE-binding monocytes, following stimulation with LPS. In addition, IgE cross-linking induced IL-8 production by both peripheral blood basophils and IgE-binding monocytes. IL-8 production was compared between healthy horses and those with a naturally occurring IgE-mediated skin allergy, Culicoides hypersensitivity. Allergic horses had significantly higher percentages of IL-8⁺ IgE-binding monocytes after IgE cross-linking. In contrast, frequencies of IL-8⁺ basophils after IgE cross-linking were similar in all horses, regardless of allergic disease, highlighting IgE-binding monocytes as a novel source of IL-8 during allergy. We concluded that IgE-binding monocytes from allergic individuals have an increased capacity for IL-8 production and likely contribute to the recruitment of innate immune cells during IgE-mediated allergy and promotion of inflammation during repeated allergen contact.

Identification of TLR2 Signalling Mechanisms Which Contribute to Barrett's and Oesophageal Adenocarcinoma Disease Progression

Simple Summary

Oesophageal adenocarcinoma (EAC) is a common type of oesophageal cancer with a rapidly rising incidence. Risk factors such as reflux, smoking, obesity and Barrett’s oesophagus cause chronic irritation and inflammation in the oesophagus. A receptor that causes inflammation, called Toll-like receptor 2 (TLR2), is expressed at higher levels in oesophageal cells from patients with Barrett’s and EAC, compared to disease-free patients. This study aimed to identify mechanisms involved in TLR2-mediated inflammation in oesophageal cells; and to assess whether TLR2 represents a therapeutic target to limit EAC development. Findings reveal that TLR2 activation in Barrett’s organoids and oesophageal cancer cells amplifies inflammation and promotes cancer development by causing the secretion of several inflammatory factors, most notably the nuclear protein, HMGB1. We demonstrate that TLR2 neutralisation efficiently blocks the inflammatory effects of TLR2 in these systems, revealing the therapeutic potential of TLR2 targeting to limit oesophageal disease and cancer progression.

Abstract

Chronic inflammation plays an important role in the pathogenesis of oesophageal adenocarcinoma (EAC) and its only known precursor, Barrett’s oesophagus (BE). Recent studies have shown that oesophageal TLR2 levels increase from normal epithelium towards EAC. TLR2 signalling is therefore likely to be important during EAC development and progression, which requires an inflammatory microenvironment. Here, we show that, in response to TLR2 stimulation, BE organoids and early-stage EAC cells secrete pro-inflammatory cytokines and chemokines which recruit macrophages to the tumour site. Factors secreted from TLR2-stimulated EAC cells are shown to subsequently activate TLR2 on naïve macrophages, priming them for inflammasome activation and inducing their differentiation to an M2/TAM-like phenotype. We identify the endogenous TLR2 ligand, HMGB1, as the factor secreted from EAC cells responsible for the observed TLR2-mediated effects on macrophages. Our results indicate that HMGB1 signalling between EAC cells and macrophages creates an inflammatory tumour microenvironment to facilitate EAC progression. In addition to identifying HMGB1 as a potential target for early-stage EAC treatment, our data suggest that blocking TLR2 signalling represents a mechanism to limit HMGB1 release, inflammatory cell infiltration and inflammation during EAC progression.

TNFα secreted by glioma associated macrophages promotes endothelial activation and resistance against anti-angiogenic therapy

One of the most prominent features of glioblastoma (GBM) is hyper-vascularization. Bone marrow-derived macrophages are actively recruited to the tumor and referred to as glioma-associated macrophages (GAMs) which are thought to provide a critical role in tumor neo-vascularization. However, the mechanisms by which GAMs regulate endothelial cells (ECs) in the process of tumor vascularization and response to anti-angiogenic therapy (AATx) is not well-understood. Here we show that GBM cells secrete IL-8 and CCL2 which stimulate GAMs to produce TNFα. Subsequently, TNFα induces a distinct gene expression signature of activated ECs including VCAM-1, ICAM-1, CXCL5, and CXCL10. Inhibition of TNFα blocks GAM-induced EC activation both in vitro and in vivo and improve survival in mouse glioma models. Importantly we show that high TNFα expression predicts worse response to Bevacizumab in GBM patients. We further demonstrated in mouse model that treatment with B20.4.1.1, the mouse analog of Bevacizumab, increased macrophage recruitment to the tumor area and correlated with upregulated TNFα expression in GAMs and increased EC activation, which may be responsible for the failure of AATx in GBMs. These results suggest TNFα is a novel therapeutic that may reverse resistance to AATx. Future clinical studies should be aimed at inhibiting TNFα as a concurrent therapy in GBMs.

Regulatory mechanisms of neutrophil migration from the circulation to the airspace

The neutrophil, a short-lived effector leukocyte of the innate immune system best known for its proteases and other degradative cargo, has unique, reciprocal physiological interactions with the lung. During health, large numbers of ‘marginated’ neutrophils reside within the pulmonary vasculature, where they patrol the endothelial surface for pathogens and complete their life cycle. Upon respiratory infection, rapid and sustained recruitment of neutrophils through the endothelial barrier, across the extravascular pulmonary interstitium, and again through the respiratory epithelium into the airspace lumen, is required for pathogen killing. Overexuberant neutrophil trafficking to the lung, however, causes bystander tissue injury and underlies several acute and chronic lung diseases. Due in part to the unique architecture of the lung’s capillary network, the neutrophil follows a microanatomic passage into the distal airspace unlike that observed in other end-organs that it infiltrates. Several of the regulatory mechanisms underlying the stepwise recruitment of circulating neutrophils to the infected lung have been defined over the past few decades; however, fundamental questions remain. In this article, we provide an updated review and perspective on emerging roles for the neutrophil in lung biology, on the molecular mechanisms that control the trafficking of neutrophils to the lung, and on past and ongoing efforts to design therapeutics to intervene upon pulmonary neutrophilia in lung disease.

Fine Particulate Matter (PM2.5) Promotes CD146 Expression in Alveolar Epithelial Cells and Cryptococcus neoformans Pulmonary Infection

Air pollution is a leading cause of increasing infectious lung diseases. Pulmonary cryptococcosis is a fatal fungal pneumonia in acquired immunodeficiency syndrome patients. In some cases, the pathogen Cryptococcus neoformans also develops dormant nodules in immunocompetent individuals. In the present study, we demonstrated that fine particulate matter (PM₂.₅) increased CD146 expression in alveolar epithelial cells and promoted C. neoformans pulmonary infection. Aryl hydrocarbon receptor (AhR) signaling was required for increased expression of CD146 in epithelial cells treated with PM₂.₅. In a murine model of pulmonary infection, PM₂.₅ promoted fungal infection, and CD146 deficiency decreased the fugal burden of C. neoformans. Our study may highlight the importance of air pollution to lung mycosis and CD146 as a target for preventing infectious lung diseases.

Blocking IL1 Beta Promotes Tumor Regression and Remodeling of the Myeloid Compartment in a Renal Cell Carcinoma Model: Multidimensional Analyses

PURPOSE

Intratumoral immunosuppression mediated by myeloid-derived suppressor cells (MDSC) and tumor-associated macrophages (TAM) represents a potential mechanism of immune checkpoint inhibitor (ICI) resistance in solid tumors. By promoting TAM and MDSC infiltration, IL1β may drive adaptive and innate immune resistance in renal cell carcinoma (RCC) and in other tumor types.

EXPERIMENTAL DESIGN

Using the RENCA model of RCC, we evaluated clinically relevant combinations of anti-IL1β plus either anti-PD-1 or the multitargeted tyrosine kinase inhibitor (TKI), cabozantinib. We performed comprehensive immune profiling of established RENCA tumors via multiparameter flow cytometry, tumor cytokine profiling, and single-cell RNA sequencing (RNA-seq). Similar analyses were extended to the MC38 tumor model.

RESULTS

Analyses via multiparameter flow cytometry, tumor cytokine profiling, and single-cell RNA-seq showed that anti-IL1β reduces infiltration of polymorphonuclear MDSCs and TAMs. Combination treatment with anti-IL1β plus anti-PD-1 or cabozantinib showed increased antitumor activity that was associated with decreases in immunosuppressive MDSCs and increases in M1-like TAMs.

CONCLUSIONS

Single-cell RNA-seq analyses show that IL1β blockade and ICI or TKI remodel the myeloid compartment through nonredundant, relatively T-cell-independent mechanisms. IL1β is an upstream mediator of adaptive myeloid resistance and represents a potential target for kidney cancer immunotherapy.