Mechanisms involved in enhancement of matrix metalloproteinase-9 expression in macrophages by interleukin-33

MiR-548t-5p regulates pancreatic ductal adenocarcinoma metastasis through an IL-33-dependent crosstalk between cancer cells and M2 macrophages

IL-33 has been associated with pro- and anticancer functions in cancer. However, its role in pancreatic cancer metastasis remains unknown. This study aimed to explore the role of miR-548t-5p/IL-33 axis in the metastasis of pancreatic cancer. Luciferase activity assay, qRT-PCR, Western blot and ELISA were performed to prove whether IL-33 is the target of miR-548t-5p. In vivo metastasis assay and cellular transwell assay were performed to explore the role of miR-548t-5p/IL-33 axis in the invasion and metastasis of pancreatic cancer. Co-culture experiments and immunohistochemistry were performed to observe whether IL-33 affects cell invasion and metastasis dependent on the involvement of M2 macrophages. THP-1 cell induction experiment and flow cytometry were performed to explore the effect of IL-33 on macrophage polarization. CCK-8, colony formation, cell apoptosis, cell cycle, cell wound healing and transwell assay were performed to investigate the effect of IL-33 induced M2 macrophages on cell malignant biological behavior by coculturing pancreatic cancer cells with the conditioned medium (CM) from macrophages. We found that miR-548t-5p regulated the expression and secretion of IL-33 in pancreatic cancer cells by directly targeting IL-33 mRNA. IL-33 secreted by cancer cells promoted the recruitment and activation of macrophages to a M2-like phenotype. In turn, IL-33 induced M2 macrophages promoted the migration and invasion of cancer cells. Moreover, IL-33 affected pancreatic cancer cell invasion dependent on the involvement of M2 macrophages in the co-culture system. Thus, our study suggested that manipulation of this IL-33-dependent crosstalk has a therapeutic potential for the treatment of pancreatic cancer metastasis.

The Mechanism of Interleukin 33-Induced Stimulation of Interleukin 6 in MLO-Y4 Cells

The differentiation and function of osteocytes are controlled by surrounding cells and mechanical stress; however, the detailed mechanisms are unknown. Recent findings suggest that IL-33 is highly expressed in periodontal tissues in orthodontic tooth movement. The present study aimed to elucidate the effect of IL-33 on the expression of regulatory factors for bone remodeling and their molecular mechanisms in the osteocyte-like cell line MLO-Y4. MLO-Y4 cells were treated with IL-33, and the activation of intracellular signaling molecules and transcriptional factors was determined using Western blot analysis and chromatin immunoprecipitation assay. IL-33 treatment enhanced the expression of IL-6 in MLO-Y4 cells, which was suppressed by the knockdown of the IL-33 receptor ST2L. Additionally, IL-33 treatment induced activation of NF-κB, JNK/AP-1, and p38 MAPK signaling pathways in MLO-Y4 cells. Moreover, pretreatment with specific inhibitors of NF-κB, p38 MAPK, and JNK/AP-1 attenuated the IL-33-induced expression of IL-6. Furthermore, chromatin immunoprecipitation indicated that IL-33 increased c-Jun recruitment to the IL-6 promoter. Overall, these results suggest that IL-33 induces IL-6 expression and regulates osteocyte function via activation of the NF-κB, JNK/AP-1, and p38 MAPK pathways through interaction with ST2L receptors on the plasma membrane.

IL33-mediated NPM1 promotes fibroblast-to-myofibroblast transition via ERK/AP-1 signaling in silica-induced pulmonary fibrosis

Silicosis is a global occupational pulmonary disease due to the accumulation of silica dust in the lung. Lacking effective clinical drugs makes the treatment of this disease quite challenging in clinics largely because the pathogenic mechanisms remain obscure. Interleukin 33 (IL33), a pleiotropic cytokine, could promote wound healing and tissue repair via the receptor ST2. However, the mechanisms governing the involvement of IL33 in silicosis progression remain to be further explored. Here, we demonstrated that the IL33 levels in the lung sections were significantly overexpressed after bleomycin and silica treatment. Chromatin immunoprecipitation assay, knockdown, and reverse experiments were performed in lung fibroblasts to prove gene interaction following exogenous IL33 treatment or cocultured with silica-treated lung epithelial cells. Mechanistically, we illustrated that silica-stimulated lung epithelial cells secreted IL33 and further promoted the activation, proliferation, and migration of pulmonary fibroblasts by activating the ERK/AP-1/NPM1 signaling pathway in vitro. And more, treatment with NPM1 siRNA-loaded liposomes markedly protected mice from silica-induced pulmonary fibrosis in vivo. In conclusion, the involvement of NPM1 in the progression of silicosis is regulated by the IL33/ERK/AP-1 signaling axis, which is the potential therapeutic target candidate in developing novel antifibrotic strategies for pulmonary fibrosis.

Extracellular ATP accelerates cell death and decreases tight junction protein ZO-1 in hypoxic cochlear strial marginal cells in neonatal rats

In the cochlear, extracellular ATP (eATP) plays an important role in both physiological and pathological processes, but its role in the hypoxic cochlear remains unclear. The present study aims to investigate the relationship between eATP and hypoxic marginal cells (MCs) in the stria vascularis in cochlear. Combining various methodologies, we found that eATP accelerates cell death and decreases tight junction protein zonula occludens-1 (ZO-1) in hypoxic MCs. Flow cytometry and western blot analyses revealed an increase in apoptosis levels and suppression of autophagy, indicating that eATP causes additional cell death by increasing the apoptosis of hypoxic MCs. Given that autophagy inhibits apoptosis to protect MCs under hypoxia, apoptosis is probably enchanced by suppressing autophagy. Interleukin-33(IL-33)/suppression of tumorigenicity-2(ST-2)/matrix metalloprotein 9(MMP9) pathway activation was also observed during the process. Further experiments involving the use of additional IL-33 protein and an MMP9 inhibitor indicated that this pathway is responsible for the damage to the ZO-1 protein in hypoxic MCs. Our study revealed the adverse effect of eATP on the survival and ZO-1 protein expression of hypoxic MCs, as well as the underlying mechanism.

Ion Channels as Potential Tools for the Diagnosis, Prognosis, and Treatment of HPV-Associated Cancers

The human papilloma virus (HPV) group comprises approximately 200 genetic types that have a special affinity for epithelial tissues and can vary from producing benign symptoms to developing into complicated pathologies, such as cancer. The HPV replicative cycle affects various cellular and molecular processes, including DNA insertions and methylation and relevant pathways related to pRb and p53, as well as ion channel expression or function. Ion channels are responsible for the flow of ions across cell membranes and play very important roles in human physiology, including the regulation of ion homeostasis, electrical excitability, and cell signaling. However, when ion channel function or expression is altered, the channels can trigger a wide range of channelopathies, including cancer. In consequence, the up- or down-regulation of ion channels in cancer makes them attractive molecular markers for the diagnosis, prognosis, and treatment of the disease. Interestingly, the activity or expression of several ion channels is dysregulated in HPV-associated cancers. Here, we review the status of ion channels and their regulation in HPV-associated cancers and discuss the potential molecular mechanisms involved. Understanding the dynamics of ion channels in these cancers should help to improve early diagnosis, prognosis, and treatment in the benefit of HPV-associated cancer patients.

Loss of myeloid Tsc2 predisposes to angiotensin II-induced aortic aneurysm formation in mice

RATIONALE

Genetic studies have proved the involvement of Tuberous sclerosis complex subunit 2 (Tsc2) in aortic aneurysm. However, the exact role of macrophage Tsc2 in the vascular system remains unclear. Here, we examined the potential function of macrophage Tsc2 in the development of aortic remodeling and aortic aneurysms.

METHODS AND RESULTS

Conditional gene knockout strategy combined with histology and whole-transcriptomic analysis showed that Tsc2 deficiency in macrophages aggravated the progression of aortic aneurysms along with an upregulation of proinflammatory cytokines and matrix metallopeptidase-9 in the angiotensin II-induced mouse model. G protein-coupled receptor 68 (Gpr68), a proton-sensing receptor for detecting the extracellular acidic pH, was identified as the most up-regulated gene in Tsc2 deficient macrophages compared with control macrophages. Additionally, Tsc2 deficient macrophages displayed higher glycolysis and glycolytic inhibitor 2-deoxy-D-glucose treatment partially attenuated the level of Gpr68. We further demonstrated an Tsc2-Gpr68-CREB network in macrophages that regulates the inflammatory response, proteolytic degradation and vascular homeostasis. Gpr68 inhibition largely abrogated the progression of aortic aneurysms caused by Tsc2 deficiency in macrophages.

CONCLUSIONS

The findings reveal that Tsc2 deficiency in macrophages contributes to aortic aneurysm formation, at least in part, by upregulating Gpr68 expression, which subsequently drives proinflammatory processes and matrix metallopeptidase activation. The data also provide a novel therapeutic strategy to limit the progression of the aneurysm resulting from Tsc2 mutations.

Emerging Effects of IL-33 on COVID-19

Since the start of COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), more than 6 million people have lost their lives worldwide directly or indirectly. Despite intensified efforts to clarify the immunopathology of COVID-19, the key factors and processes that trigger an inflammatory storm and lead to severe clinical outcomes in patients remain unclear. As an inflammatory storm factor, IL-33 is an alarmin cytokine, which plays an important role in cell damage or infection. Recent studies have shown that serum IL-33 is upregulated in COVID-19 patients and is strongly associated with poor outcomes. Increased IL-33 levels in severe infections may result from an inflammatory storm caused by strong interactions between activated immune cells. However, the effects of IL-33 in COVID-19 and the underlying mechanisms remain to be fully elucidated. In this review, we systematically discuss the biological properties of IL-33 under pathophysiological conditions and its regulation of immune cells, including neutrophils, innate lymphocytes (ILCs), dendritic cells, macrophages, CD4⁺ T cells, Th17/Treg cells, and CD8⁺ T cells, in COVID-19 phagocytosis. The aim of this review is to explore the potential value of the IL-33/immune cell pathway as a new target for early diagnosis, monitoring of severe cases, and clinical treatment of COVID-19.

Dual Immune Regulatory Roles of Interleukin-33 in Pathological Conditions

Interleukin-33 (IL-33), a member of the IL-1 cytokine family and a multifunctional cytokine, plays critical roles in maintaining host homeostasis and in pathological conditions, such as allergy, infectious diseases, and cancer, by acting on multiple types of immune cells and promoting type 1 and 2 immune responses. IL-33 is rapidly released by immune and non-immune cells upon stimulation by stress, acting as an “alarmin” by binding to its receptor, suppression of tumorigenicity 2 (ST2), to trigger downstream signaling pathways and activate inflammatory and immune responses. It has been recognized that IL-33 displays dual-functioning immune regulatory effects in many diseases and has both pro- and anti-tumorigenic effects, likely depending on its primary target cells, IL-33/sST2 expression levels, cellular context, and the cytokine microenvironment. Herein, we summarize our current understanding of the biological functions of IL-33 and its roles in the pathogenesis of various conditions, including inflammatory and autoimmune diseases, infections, cancers, and cases of organ transplantation. We emphasize the nature of context-dependent dual immune regulatory functions of IL-33 in many cells and diseases and review systemic studies to understand the distinct roles of IL-33 in different cells, which is essential to the development of more effective diagnoses and therapeutic approaches for IL-33-related diseases.

Elevated carcinoembryonic antigen predicts rapidly progressive interstitial lung disease in clinically amyopathic dermatomyositis

OBJECTIVES

The present study aimed to determine the correlation between serum carcinoembryonic antigen (CEA) level and the severity of interstitial lung disease (ILD) in clinically amyopathic DM (CADM) patients.

METHODS

We performed a retrospective study including 41 Chinese CADM patients without malignancy. Serum CEA levels, clinical and laboratory findings were collected. Association tests between CEA levels and disease activity parameters were performed.

RESULTS

Among the 41 patients, 16 (39.0%) developed rapidly progressive (RP)-ILD; of them, 14 (87.5%) had elevated serum CEA levels. Multivariate logistic regression analysis indicated that an elevated serum CEA level was an independent risk factor for RP-ILD. The incidence of elevated CEA level was significantly higher in patients with RP-ILD than in those without RP-ILD (87.5 vs 16.0%, P < 0.001). Furthermore, CEA levels were higher in patients with CADM with RP-ILD [26.87 (6.71) μg/l] than in those without RP-ILD [3.23 (0.64) μg/l] (P < 0.001). CEA levels in CADM patients were associated with the ferritin, alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase levels, and CT scores of the lungs. Also, elevated CEA levels are related to the organizing pneumonia pattern and lower lung zone consolidation in high-resolution CT. Moreover, the cumulative survival rate was significantly lower (68.4 vs 31.6%, P < 0.001) in the group with a CEA level >8.75 μg/l than that in the group with a CEA level <8.75 μg/l.

CONCLUSIONS

An elevated serum CEA level is common in patients with CADM, and a higher serum CEA level is a powerful indicator of RP-ILD and poor prognosis in those patients.

Interleukin-33 promotes invasiveness of human ovarian endometriotic stromal cells through the ST2/MAPK/MMP-9 pathway activated by 17β-estradiol

OBJECTIVE

Endometriosis is an estrogen-dependent, benign, and chronic gynecological disorder occurring in women of reproductive age. Although the pathogenesis of endometriosis is poorly understood, implantation theory indicates that viable endometrial cells shed from the endometrium into the pelvic peritoneum or ovaries, possibly through retrograde menstruation, and then reattach, invade, and damage other tissues. Interleukin (IL)-33, a new member of the IL-1 superfamily, is mainly upregulated by stromal cells following proinflammatory stimulation. Matrix metalloproteinases (MMPs) are involved in the degradation and reconstruction of the extracellular matrix. MMP-9 participates in the pathogenesis of endometriosis by promoting the invasion of endometriotic cells. This study investigated the effect of IL-33 on the cell invasion ability of and MMP-9 expression in human stromal cells derived from ovarian endometrioma (hOVEN-SCs).

MATERIALS AND METHODS

We isolated hOVEN-SCs from human ovarian endometrioma. Gene expression was analyzed using the Illumina Human WG-6 v2 Expression BeadChips microarray platform and through reverse transcription-polymerase chain reaction. Cell migration and invasion were examined by performing the transwell chamber assay.

RESULTS

We found that 17β-estradiol could increase the expression of IL-33 and ST2 through the estrogen receptor pathway in hOVEN-SCs. Moreover, IL-33 upregulated MMP-9 expression in and enhanced the invasion ability of hOVEN-SCs through the ST2/MAPK signaling pathway. Our results showed that MMP-9 expression was essential for IL-33-induced cell invasion.

CONCLUSION

Our main finding is that 17β-estradiol could increase IL-33 expression through the estrogen receptor pathway and activate MMP-9 expression in and invasion ability of hOVEN-SCs through the IL-33/ST2/MAPK signaling pathway. The results of this study and further related studies may provide new strategies for the prevention and treatment of endometriosis.

The Janus Face of IL-33 Signaling in Tumor Development and Immune Escape

Simple Summary

Interleukin-33 (IL-33) is often released from damaged cells, acting as a danger signal. IL-33 exerts its function by interacting with its receptor suppression of tumorigenicity 2 (ST2) that is constitutively expressed on most immune cells. Therefore, IL-33/ST2 signaling can modulate immune responses to participate actively in a variety of pathological conditions, such as cancer. Like a two-faced Janus, which faces opposite directions, IL-33/ST2 signaling may play contradictory roles on its impact on cancer progression through both immune and nonimmune cellular components. Accumulating evidence demonstrates both pro- and anti-tumorigenic properties of IL-33, depending on the complex nature of different tumor immune microenvironments. We summarize and discuss the most recent studies on the contradictory effects of IL-33 on cancer progression and treatment, with a goal to better understanding the various ways for IL-33 as a therapeutic target.

Abstract

Interleukin-33 (IL-33), a member of the IL-1 cytokine family, plays a critical role in maintaining tissue homeostasis as well as pathological conditions, such as allergy, infectious disease, and cancer, by promoting type 1 and 2 immune responses. Through its specific receptor ST2, IL-33 exerts multifaceted functions through the activation of diverse intracellular signaling pathways. ST2 is expressed in different types of immune cells, including Th2 cells, Th1 cells, CD8⁺ T cells, regulatory T cells (T_reg), cytotoxic NK cells, group 2 innate lymphoid cells (ILC2s), and myeloid cells. During cancer initiation and progression, the aberrant regulation of the IL-33/ST2 axis in the tumor microenvironment (TME) extrinsically and intrinsically mediates immune editing via modulation of both innate and adaptive immune cell components. The summarized results in this review suggest that IL-33 exerts dual-functioning, pro- as well as anti-tumorigenic effects depending on the tumor type, expression levels, cellular context, and cytokine milieu. A better understanding of the distinct roles of IL-33 in epithelial, stromal, and immune cell compartments will benefit the development of a targeting strategy for this IL-33/ST2 axis for cancer immunotherapy.

3D spheroid culture models for chondrocytes using polyethylene glycol-coated microfabricated chip

As chondrocytes fail to retain their chondrogenic potential in two-dimensional monolayer cultures, several three-dimensional culture systems have been employed for investigating the physiology and pathophysiology in articular cartilage tissues. In this study, we introduced a polyethylene glycol-coated microfabricated chip that enables spheroid formation from ATDC5 cell line, commonly used as a model for in vitro chondrocyte research. ATDC5 cells cultured in our devices aggregated immediately and generated a single spheroid per well within 24 h. Most cells in spheroids cultured in differentiation medium were viable and the circular shape and smooth surface of the spheroid were maintained up to 14 d in culture. We also detected potent hypoxia conditions, a key factor in chondrogenesis, in whole lesions of ATDC5 spheroids. Expression of chondrogenesis-related genes and type X collagen protein was significantly increased in ATDC5 spheroids grown in differentiation medium, compared with monolayer-cultured ATDC5 cells. We also demonstrated that the differentiation medium-induced Akt protein phosphorylation was upregulated in ATDC5 cells cultured in our spheroid device, suggesting that enhancement of chondrogenic potential in ATDC5 spheroids results from PI3/Akt signaling activation. These results indicated that our spheroid culture system could constitute a high-throughput strategy approach towards elucidating the molecular mechanisms that regulate chondrogenesis.

The roles of macrophage polarization in the host immune response to sepsis

Sepsis is a life-threatening clinical syndrome caused by infection. Its pathogenesis is complex and entails coagulation dysfunction, inflammation, and immune disorders. Macrophages are important components of innate and adaptive immunity that are highly heterogeneous and plastic. They can polarize into a multi-dimensional spectrum of phenotypes with different functions relating to immune regulation in response to changes in the microenvironment of specific tissues. We reviewed studies that examined the role of macrophage polarization with a focus on the classical activated (M1-like) and alternative activated (M2-like) macrophages as the two main phenotypes involved in the host immune response to sepsis. A complex regulatory network is involved in the process of macrophage polarization, which is influenced by a variety of signaling molecules, transcription factors, epigenetic modifications, and metabolic reprogramming. M1-like macrophages release large quantities of pro-inflammatory mediators, while M2-like macrophages release large quantities of anti-inflammatory mediators. An imbalance between M1-like and M2-like macrophages induces the occurrence and development of sepsis. Therefore, targeted regulation of the process of macrophage polarization could be a useful approach to normalize the immune balance of the host, offering a new treatment modality for different stages of sepsis.

Transcription factors regulated by cAMP in smooth muscle of the myometrium at human parturition

Cyclic adenosine monophosphate (cAMP) contributes to maintenance of a quiescent (relaxed) state in the myometrium (i.e. uterine smooth muscle) during pregnancy, which most commonly has been attributed to activation of protein kinase A (PKA). PKA-mediated phosphorylation of cytosolic contractile apparatus components in myometrial smooth muscle cells (mSMCs) are known to promote relaxation. Additionally, PKA also regulates nuclear transcription factor (TF) activity to control expression of genes important to the labour process; these are mostly involved in actin-myosin interactions, cell-to-cell connectivity and inflammation, all of which influence mSMC transition from a quiescent to a contractile (pro-labour) phenotype. This review focuses on the evidence that cAMP modulates the activity of TFs linked to pro-labour gene expression, predominantly cAMP response element (CRE) binding TFs, nuclear factor κB (NF-κB), activator protein 1 (AP-1) family and progesterone receptors (PRs). This review also considers the more recently described exchange protein directly activated by cAMP (EPAC) that may oppose the pro-quiescent effects of PKA, as well as explores findings from other cell types that have the potential to be of novel relevance to cAMP action on TF function in the myometrium.

Effects of oxidative stress-induced increases in Zn2+ concentrations in human gingival epithelial cells

BACKGROUND AND OBJECTIVE

Previous studies have reported that oxidative stress increases intracellular Zn²⁺ concentrations and induces cytotoxicity. However, no studies have investigated whether oxidative stress induces such changes in periodontal tissue cells. In the present study, we investigated the effect of oxidative stress on intracellular Zn²⁺ concentration in periodontium constituent cells and its potential relationship with periodontal disease.

METHODS

We analyzed changes in intracellular Zn²⁺ concentrations in human gingival epithelial (epi4) cells treated with hydrogen peroxide (H₂ O₂ ). The fluorescent probes FluoZin-3 AM and CellTracker Green CMFDA were used to detect intracellular Zn²⁺ and thiol groups, respectively. Western blot analyses, luciferase reporter assays, and real-time polymerase chain reaction (PCR) analyses were performed to examine the effect of intracellular Zn²⁺ on epi4 cells.

RESULTS

H₂ O₂ treatment increased intracellular concentrations of Zn²⁺ in epi4 cells by facilitating the movement of Zn²⁺ from cellular nonprotein thiols to the cytoplasm and promoting cell membrane permeability to Zn²⁺ . Furthermore, H₂ O₂ -induced increases in intracellular Zn²⁺ activated the p38 cAMP response element-binding protein/mitogen-activated protein kinase (p38 CREB/MAPK) cascade, upregulated nuclear factor kappa B (NF-κB) DNA binding, and increased the expression of inflammatory cytokines and matrix metallopeptidase-9 (MMP-9).

CONCLUSION

Increases in intracellular Zn²⁺ induced by oxidative stress activate signaling pathways involved in inflammation, potentially contributing to the progression of periodontal disease.

Lgr4 Governs a Pro-Inflammatory Program in Macrophages to Antagonize Post-Infarction Cardiac Repair

RATIONALE

Macrophages are critically involved in wound healing following myocardial infarction (MI). Lgr4, a member of LGR (leucine-rich repeat-containing G protein-coupled receptor) family, is emerging as a regulator of macrophage-associated immune responses. However, the contribution of Lgr4 to macrophage phenotype and function in the context of MI remains unclear.

OBJECTIVE

To determine the role of macrophage Lgr4 in MI and to dissect the underlying mechanisms.

METHODS AND RESULTS

During early inflammatory phase of MI, infarct macrophages rather than neutrophils expressed high level of Lgr4. Macrophage-specific Lgr4 knockout mice had no baseline cardiovascular defects but manifested improved heart function, modestly reduced infarct size, decreased early mortality due to cardiac rupture, and ameliorated adverse remodeling after MI. Improved outcomes in macrophage-specific Lgr4 knockout mice subjected to MI were associated with mitigated ischemic injury and optimal infarct healing, as determined by reduction of cardiac apoptosis in the peri-infarct zone, attenuation of local myocardial inflammatory response, decrease of matrix metalloproteinase expression in the infarct, enhancement of angiogenesis, myofibroblast proliferation, and collagen I deposition in reparative granulation tissue as well as formation of collagen-rich scar. More importantly, macrophage-specific Lgr4 knockout infarcts had reduced numbers of infiltrating leukocytes and inflammatory macrophages but harbored abundant reparative macrophage subsets. Lgr4-null infarct macrophages exhibited a less inflammatory transcriptional signature. These findings were further supported by transcriptomic profiling data showing repression of multiple pathways and broad-spectrum genes associated with proinflammatory responses in macrophage-specific Lgr4 knockout infarcts. Notably, we discovered that Lgr4-mediated functional phenotype programing in infarct macrophages was at least partly attributed to regulation of AP (activator protein)-1 activity. We further demonstrated that the synergistic effects of Lgr4 on AP-1 activation in inflammatory macrophages occurred via enhancing CREB (cAMP response element-binding protein)-mediated c-Fos, Fosl1, and Fosb transactivation.

CONCLUSIONS

Together, our data highlight the significance of Lgr4 in governing proinflammatory phenotype of infarct macrophages and postinfarction repair.

Lipopolysaccharide disrupts the cochlear blood-labyrinth barrier by activating perivascular resident macrophages and up-regulating MMP-9

OBJECTIVE

To determine the distribution of perivascularresident macrophages (PVMs) in BLB and their relationship with capillaries, and to explore the possible mechanisms responsible for lipopolysaccharide (LPS)-induced activation of PVMs and the breakdown of BLB.

METHODS

Adult Balb/c mice were either trans-tympanically injected with LPS, or mock-treated. Auditory brainstem response was tested before and 48 h after treatments. Distribution of pericytes, PVMs and capillaries was analyzed by immunohistochemical staining, and BLB permeability was estimated by FITC-dextran leakage assay. Ultrastructure of stria vascularis was examined by transmission electron microscope. Protein and mRNA level of matrix metallopeptidase 9 (MMP-9), zona occludens-1 (ZO-1), interleukin-33 (IL-33) and its receptor suppression of tumorigenicity 2 (ST2) was measured by IHC and qRT-PCR.

RESULTS

Unlike pericytes that surround one capillary, PVMs branched to connect with more than one capillary. LPS caused hearing loss in mice. Following LPS challenge, cochleae showed vascular leakage in stria vascularis, and PVMs presented morphological changes including reduced contact with capillaries. TEM revealed a reduced number of tight junction contact points between endothelial cells and a wider space between PVMs, pericytes and endothelial cells. The mRNA and protein levels of MMP-9 and ST2 in stria vascularis were up-regulated, while ZO-1 were down-regulated after exposure to LPS.

CONCLUSIONS

Our results suggest that PVMs may play a more significant role than pericytes in maintaining the integrity of BLB. Our findings also reveal a possible mechanism contributing to LPS-induced activation of PVMs, breakdown of BLB and hearing loss.

Safranal Alleviates Dextran Sulfate Sodium-Induced Colitis and Suppresses Macrophage-Mediated Inflammation

Introduction:Crocus sativus (saffron) is widely used in China, Iran, and India for dyeing and as a food additive and medicinal plant. Safranal, as one of the main constituents of saffron, is responsible for its aroma and has been reported to have anticancer, antioxidant, and anti-inflammation properties.

Objective: In this study, we investigated the anti-inflammatory effects of Safranal in RAW264.7 cells, bone marrow-derived macrophages (BMDMs), and dextran sulfate sodium (DSS)-induced colitis mice.

Methods: Safranal toxicity was determined using an MTT assay. We evaluated the inhibitory effect of nitric oxide (NO) and levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in RAW264.7 cells and BMDMs. We assessed the inhibitory effect of pro-inflammatory cytokines, and the mRNA expressions of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), classical inflammatory pathways (MAPK and NF-κB), and the nuclear translocation factors AP-1 and NF-κB p65 were investigated. The in vivo anti-inflammatory effects of Safranal were assessed in a DSS-induced colitis model. DSS3.5% was used to induce colitis in mice with or without Safranal for 7 days; weight and disease activity index (DAI) were recorded daily. At the end of the experiment, the colon, mesenteric lymph nodes (MLNs), and spleen were collected for flow cytometry, ELISA, and Western blot analysis.

Results: Safranal suppressed NO production, iNOS, and COX-2 in lipopolysaccharide (LPS)-stimulated RAW264.7 cells and BMDMs. Safranal decreased the production and mRNA expression of IL-6 and TNF-α in the RAW264.7 cell line and inhibited the phosphorylation and nuclear translocation of components of the MAPK and NF-κB pathways. Safranal alleviated clinical symptoms in the DSS-induced colitis model, and colon histology showed decreased severity of inflammation, depth of inflammatory involvement, and crypt damage. Immunohistochemical staining and flow cytometry showed reduced macrophage infiltration in colonic tissues and macrophage numbers in MLNs and the spleen. The levels of colonic IL-6 and TNF-α also decreased in Safranal-treated colitis mice. This study elucidates the anti-inflammation activity of Safranal, which may be a candidate for inflammatory bowel syndrome (IBD) therapy.

The Pleiotropic Immunomodulatory Functions of IL-33 and Its Implications in Tumor Immunity

Interleukin-33 (IL-33) is a IL-1 family member of cytokines exerting pleiotropic activities. In the steady-state, IL-33 is expressed in the nucleus of epithelial, endothelial, and fibroblast-like cells acting as a nuclear protein. In response to tissue damage, infections or necrosis IL-33 is released in the extracellular space, where it functions as an alarmin for the immune system. Its specific receptor ST2 is expressed by a variety of immune cell types, resulting in the stimulation of a wide range of immune reactions. Recent evidences suggest that different IL-33 isoforms exist, in virtue of proteolytic cleavage or alternative mRNA splicing, with potentially different biological activity and functions. Although initially studied in the context of allergy, infection, and inflammation, over the past decade IL-33 has gained much attention in cancer immunology. Increasing evidences indicate that IL-33 may have opposing functions, promoting, or dampening tumor immunity, depending on the tumor type, site of expression, and local concentration. In this review we will cover the biological functions of IL-33 on various immune cell subsets (e.g., T cells, NK, Treg cells, ILC2, eosinophils, neutrophils, basophils, mast cells, DCs, and macrophages) that affect anti-tumor immune responses in experimental and clinical cancers. We will also discuss the possible implications of diverse IL-33 mutations and isoforms in the anti-tumor activity of the cytokine and as possible clinical biomarkers.

Elevated IL-33 promotes expression of MMP2 and MMP9 via activating STAT3 in alveolar macrophages during LPS-induced acute lung injury

Background

Pulmonary inflammation and endothelial barrier permeability increase in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) induced by pro-inflammatory cytokines and matrix metalloproteinases (MMPs). However, the relationship between pro-inflammatory cytokines and MMPs in ALI/ARDS remains poorly understood.

Methods

A lipopolysaccharide (LPS)-induced ALI rat model was established through intratracheal instillation. The wet/dry ratios of lung tissues were measured, and bronchoalveolar lavage fluid (BALF) was collected to test protein concentrations, total cell/macrophage numbers, and pro-inflammatory cytokine levels. LPS-treated alveolar macrophages were utilized in in vitro experiments. The expression and secretion of MMPs were respectively detected using quantitative PCR, Western blotting and ELISA assays.

Results

The levels of IL-33 and MMP2/9 in BALF increased in all the ALI rats with severe lung injury. LPS-induced IL-33 autocrine upregulated the expression of MMP2 and MMP9 through activating STAT3. Neutralizing IL-33 in culture medium with specific antibodies suppressed the expression and secretion of MMP2 and MMP9 in LPS-treated alveolar macrophages. Consistently, eliminating IL-33 decreased the levels of MMP2 and MMP9 in BALF and alleviated lung injury in ALI rats.

Conclusion

The IL-33/STAT3/MMP2/9 regulatory pathway is activated in alveolar macrophages during acute lung injury, which may exacerbate the pulmonary inflammation.

The Pro-tumorigenic IL-33 Involved in Antitumor Immunity: A Yin and Yang Cytokine

Interleukin-33 (IL-33), considered as an alarmin released upon tissue stress or damage, is a member of the IL-1 family and binds the ST2 receptor. First described as a potent initiator of type 2 immune responses through the activation of T helper 2 (T_H2) cells and mast cells, IL-33 is now also known as an effective stimulator of T_H1 immune cells, natural killer (NK) cells, iNKT cells, and CD8 T lymphocytes. Moreover, IL-33 was shown to play an important role in several cancers due to its pro and anti-tumorigenic functions. Currently, IL-33 is a possible inducer and prognostic marker of cancer development with a direct effect on tumor cells promoting tumorigenesis, proliferation, survival, and metastasis. IL-33 also promotes tumor growth and metastasis by remodeling the tumor microenvironment (TME) and inducing angiogenesis. IL-33 favors tumor progression through the immune system by inducing M2 macrophage polarization and tumor infiltration, and upon activation of immunosuppressive cells such as myeloid-derived suppressor cells (MDSC) or regulatory T cells. The anti-tumor functions of IL-33 also depend on infiltrated immune cells displaying T_H1 responses. This review therefore summarizes the dual role of this cytokine in cancer and suggests that new proposals for IL-33-based cancer immunotherapies should be considered with caution.

Molecular mechanisms of IL-33-mediated stromal interactions in cancer metastasis

Molecular mechanisms underlying the cancer stroma in metastasis need further exploration. Here, we discovered that cancer-associated fibroblasts (CAFs) produced high levels of IL-33 that acted on tumor-associated macrophages (TAMs), causing them to undergo the M1 to M2 transition. Genomic profiling of metastasis-related genes in the IL-33-stimulated TAMs showed a >200-fold increase of MMP9. Signaling analysis demonstrated the IL-33-ST2-NF-κB-MMP9-laminin pathway that governed tumor stroma-mediated metastasis. In mouse and human fibroblast-rich pancreatic cancers, genetic deletion of IL-33, ST2, or MMP9 markedly blocked metastasis. Pharmacological inhibition of NF-κB and MMP9 also blocked cancer metastasis. Deletion of IL-33, ST2, or MMP9 restored laminin, a key basement membrane component associated with tumor microvessels. Together, our data provide mechanistic insights on the IL-33-NF-κB-MMP9-laminin axis that mediates the CAF-TAM-committed cancer metastasis. Thus, targeting the CAF-TAM-vessel axis provides an outstanding therapeutic opportunity for cancer treatment.

Notch-1 signaling activation sustains overexpression of interleukin 33 in the epithelium of nasal polyps

BACKGROUND

Alterations in the nasal epithelial barrier homeostasis and increased interleukin 33 (IL-33) expression contribute to the pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP).

AIMS

As Notch-1 signaling is crucial in repair processes of mucosa, the current study assessed Notch-1/Jagged-1 signaling and IL-33 in the epithelium of nasal polyps biopsies from allergic (A-CRSwNP; n = 9) and not allergic (NA-CRSwNP; n = 9) subjects by immunohistochemistry. We also assessed, in a model of nasal epithelial cells, the effects of stimulation of Notch-1 with Jagged-1 on the expression of IL-33 (by flow cytometry, immunofluorescence, and immunocytochemistry), Jagged-1 (by flow cytometry), and p-CREB transcription factor (by western blot analysis).

RESULTS

Ex vivo (a) in normal epithelium, the expression of Notch-1 and IL-33 were higher in NA-CRSwNP than in A-CRSwNP; (b) in metaplastic epithelium, the expression of Notch-1, Jagged-1, and IL-33 were higher in NA-CRSwNP than in A-CRSwNP; (c) in hyperplastic epithelium, the expression of Notch-1, Jagged-1, and IL-33 were higher in A-CRSwNP than in NA-CRSwNP; and (d) in basal epithelial cells, no differences were observed in the expression of Jagged-1, IL-33, and Notch-1. The expression of Notch-1 significantly correlated with the expression of IL-33. In vitro, stimulation of Notch-1 with Jagged-1 induced the expression of (a) Jagged-1; (b) IL-33; and (c) p-CREB transcription factor. The inhibitor of Notch-1, DAPT, reduced all the effects of Jagged-1 on nasal epithelial cells.

CONCLUSIONS

The data herein provided support, for the first time, a putative role of Notch-1/Jagged-1 signaling in the overexpression of IL-33 in the epithelium of nasal polyps from patients with CRSwNP.

The invasiveness of human cervical cancer associated to the function of NaV1.6 channels is mediated by MMP-2 activity

Voltage-gated sodium (Na_V) channels have been related with cell migration and invasiveness in human cancers. We previously reported the contribution of Na_V1.6 channels activity with the invasion capacity of cervical cancer (CeCa) positive to Human Papilloma Virus type 16 (HPV16), which accounts for 50% of all CeCa cases. Here, we show that Na_V1.6 gene (SCN8A) overexpression is a general characteristic of CeCa, regardless of the HPV type. In contrast, no differences were observed in Na_V1.6 channel expression between samples of non-cancerous and cervical intraepithelial neoplasia. Additionally, we found that CeCa cell lines, C33A, SiHa, CaSki and HeLa, express mainly the splice variant of SCN8A that lacks exon 18, shown to encode for an intracellularly localized Na_V1.6 channel, whereas the full-length adult form was present in CeCa biopsies. Correlatively, patch-clamp experiments showed no evidence of whole-cell sodium currents (I_Na) in CeCa cell lines. Heterologous expression of full-length Na_V1.6 isoform in C33A cells produced I_Na, which were sufficient to significantly increase invasion capacity and matrix metalloproteinase type 2 (MMP-2) activity. These data suggest that upregulation of Na_V1.6 channel expression occurs when cervical epithelium have been transformed into cancer cells, and that Na_V1.6-mediated invasiveness of CeCa cells involves MMP-2 activity. Thus, our findings support the notion about using Na_V channels as therapeutic targets against cancer metastasis.

Targeting IL-33/ST2 signaling: regulation of immune function and analgesia

INTRODUCTION

IL-33 signals through ST2 receptor and promotes inflammation by activating downstream pathways culminating in the production of pro-inflammatory mediators such as IL-1β, TNF-α, and IL-6 in an NF-κB-dependent manner. In fact, compelling evidence has demonstrated the importance of IL-33/ST2 in both innate and adaptive immune responses in diseases presenting pain as an important clinical symptom. Areas covered: IL-33 is a pleiotropic cytokine with varied immune functions. Dysregulation of this pathway has been described as a key step in varied immune responses. Further, IL-33 contributes to peripheral and spinal cord nociceptor neuron sensitization in innate and adaptive inflammatory immune responses as well as in neuropathic and cancer pain. In this sense, targeting IL-33/ST2 signaling is a promising therapeutic approach. Expert opinion: The modulation of IL-33/ST2 signaling represents a possible approach in regulating immune functions. In addition to immune function, strategies targeting IL-33/ST2 signaling pathway display a favorable preclinical analgesic profile in both acute and chronic models of pain. Therefore, IL-33-targeting therapies represent a potential target for the development of novel analgesic drugs given that IL-33 activates, for instance, neutrophils, mast cells, macrophages, astrocytes, and microglia that are important cells in the induction and maintenance of chronic pain states.