Over-expression of CXCL2 is associated with poor prognosis in patients with ovarian cancer.

BACKGROUND: In the present study, we aimed to detect the expression of CXCL2 in epithelial ovarian cancer (OC) and explore its clinical significance. METHODS: TCGA (The Cancer Genome Atlas) database was adopted to assess the significance of CXCL2. Tissue microarray and immunohistochemical staining were used to detect the expression of CXCL2 in epithelial OC, and its correlation with clinicopathological features and prognosis was statistically analyzed. RESULTS: CXCL2 was highly expressed in epithelial OC tissues compared with the adjacent tissues. Such up-regulation of CXCL2 was significantly correlated with tumor differentiation (P = .001), tumor stage (P = .01), tumor location (unilateral or bilateral) (P = .003), and metastasis (P = .003). Kaplan-Meier and Cox proportional hazards regression analyses showed that high expression of CXCL2 was not an independent predictor of poor prognosis in epithelial OC. CONCLUSIONS: Collectively, the high expression of CXCL2 might be related to the invasion and metastasis of epithelial OC.

Gefitinib-Induced Cutaneous Toxicities in Brown Norway Rats Are Associated with Macrophage Infiltration.

Gefitinib (Iressa), is a selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), used in the targeted treatment of locally advanced or metastatic non-small cell lung cancer (NSCLC). Skin toxicity is the major adverse effect observed in patients treated with EGFR-targeted TKIs such as gefitinib and erlotinib. To date, a corresponding skin animal model has not been established to address the mechanisms of these effects. Therefore, we analyzed the skin rash phenotype and its pathological features in Brown Norway (BN) rats treated with gefitinib 2.5 mg, 5.0 mg, or 10 mg/100 g/day for 4 weeks. We found that treatment with gefitinib led to weight loss, rash, itching, and hair loss in a dose-dependent manner. We also investigated the skin pathology and found that the animal model showed thickening of the epidermis, loss of moisture, and apoptosis of keratinocytes. Immunohistochemistry, flow cytometry, and analysis of monocytes and leukocytes in the blood revealed increased macrophage infiltration was associated with the cutaneous toxicities induced by gefitinib in the BN rats. Finally, we found that gefitinib-induced cutaneous toxicity is significantly associated with three inflammatory cytokines known to be secreted by activated macrophages, TREM-1, CINC-2, and CINC-3.

PDX regulates inflammatory cell infiltration via resident macrophage in LPS-induced lung injury.

Inflammatory cell infiltration contributes to the pathogenesis of acute respiratory distress syndrome (ARDS). Protectin DX (PDX), an endogenous lipid mediator, shows anti-inflammatory and proresolution bioactions. In vivo, the mice were intraperitoneally injected with PDX (0.1 µg/mouse) after intratracheal (1 mg/kg) or intraperitoneal (10 mg/kg) LPS administration. Flow cytometry was used to measure inflammatory cell numbers. Clodronate liposomes were used to deplete resident macrophages. RT-PCR, and ELISA was used to measure MIP-2, MCP-1, TNF-α and MMP9 levels. In vitro, sorted neutrophils, resident and recruited macrophages (1 × 106 ) were cultured with 1 µg/mL LPS and/or 100 nmol/L PDX to assess the chemokine receptor expression. PDX attenuated LPS-induced lung injury via inhibiting recruited macrophage and neutrophil recruitment through repressing resident macrophage MCP-1, MIP-2 expression and release, respectively. Finally, PDX inhibition of neutrophil infiltration and transmembrane was associated with TNF-α/MIP-2/MMP9 signalling pathway. These data suggest that PDX attenuates LPS-stimulated lung injury via reduction of the inflammatory cell recruitment mediated via resident macrophages.

Activation of MIP-2 and MCP-5 Expression in Methylmercury-Exposed Mice and Their Suppression by N-Acetyl-L-Cysteine.

Methylmercury (MeHg) is a well-known neurotoxin of the central nervous system (CNS). Neuroinflammation is one of the main pathways of MeHg-induced CNS impairment. This study aims to investigate the expressions of IL-6, MIP-2, and MCP-5, as biomarkers in relation with MeHg-induced CNS impairment and N-acetyl-L-cysteine (NAC) treatment in mice, as well as histopathological changes of brain tissue and clinical symptom such as ataxia. Twenty male Balb/c mice, aged 8-9 weeks, were divided into 4 groups and treated with saline (control), NAC [150 mg/kg body weight (BW) day], MeHg (4 mg Hg/kg BW), or a combination of MeHg and NAC for 17 days. MeHg induced the expression of IL-6, MIP-2, and MCP-5 in the serum, with median values (those in controls) of 55.06 (9.44), 15.94 (9.30), and 458.91 (239.91) mg/dl, respectively, and a statistical significance was observed only in IL-6 expression (p < 0.05). MIP-2 and MCP-5 expressions tended to increase in the cerebrum of MeHg-treated group compared with controls; however, the difference was not statistically significant. MeHg treatment also increased IL-6 expression in the cerebellum (7.73 and 4.81 mg/dl in MeHg-treated group and controls, respectively), with a marginal significance. NAC significantly suppressed MeHg-induced IL-6 and MIP-2 expressions in the serum (p < 0.05 for both), and slightly reduced MCP-5 expression in the cerebrum. Ataxia was observed in all MeHg-treated mice after 9-day exposure as well as the decrease of intact Purkinje cells in brain tissue (p < 0.05). These findings suggest that MeHg induced neurotoxicity by elevating the expression of IL-6, MIP-2, and MCP-5 and causing ataxia symptoms, and NAC reduced MeHg-mediated effects on the CNS.

Naringenin suppresses neutrophil infiltration into adipose tissue in high-fat diet-induced obese mice.

Recruitment of immune cells to adipose tissue is altered dramatically in obesity, which results in chronic inflammation of the adipose tissue that leads to metabolic disorders, such as insulin resistance and type 2 diabetes mellitus. The regulation of immune cell infiltration into adipose tissue has prophylactic and therapeutic implications for obesity-related diseases. We previously showed that naringenin, a citrus flavonoid, suppressed macrophage infiltration into adipose tissue by inhibiting monocyte chemoattractant protein-1 (MCP-1) expression in the progression phase to high-fat diet (HFD)-induced obesity. In the current study, we evaluated the effects of naringenin on neutrophil infiltration into adipose tissue, because neutrophils also infiltrate into adipose tissue in the progression phase to obesity. Naringenin suppressed neutrophil infiltration into adipose tissue induced by the short-term (2 weeks) feeding of a HFD to mice. Naringenin tended to inhibit the HFD-induced expression of several chemokines, including MCP-1 and MCP-3, in adipose tissue. Naringenin also inhibited MCP-3 expression in 3T3-L1 adipocytes and a co-culture of 3T3-L1 adipocytes and RAW264 macrophages. However, naringenin did not affect the expression of macrophage inflammatory protein-2 (MIP-2), an important chemokine for neutrophil migration and activation, in macrophages or in a co-culture of adipocytes and macrophages. Our results suggest that naringenin suppresses neutrophil infiltration into adipose tissue via the regulation of MCP-3 expression and macrophage infiltration.

Identification of genes and pathways, including the CXCL2 axis, altered by DNA methylation in hepatocellular carcinoma.

PURPOSE: Recent genetic studies have suggested that tumor suppressor genes are often silenced during carcinogenesis via epigenetic modification caused by methylation of promoter CpG islands. Here, we characterized genes inactivated by DNA methylation in human hepatocellular carcinoma (HCC) to identify the genes and pathways involved in DNA methylation in hepatocellular carcinoma. METHODS: Eight HCC-derived cell lines were treated with a DNA demethylating agent, 5-aza-2'-deoxycytidine. Additionally, 100 pairs of primary HCC and adjacent non-cancerous tissues as well as 15 normal liver tissues were analyzed by comprehensive gene expression analysis using microarrays. Moreover, gene set enrichment analysis identified the major molecular pathways associated with DNA methylation. Validation of gene expression and DNA methylation status was performed by real-time PCR after bisulfite modification. RESULTS: We showed that CXCL2, an immune-related chemokine, expression was significantly downregulated in tumor tissues and also significantly upregulated by DAC treatment in cell lines. Furthermore, we observed a statistically significant difference in methylation status between normal liver tissues and tumor tissues (P < 0.05). In addition, tumors with higher CXCL2 expression included significantly more numbers of multiple tumors than the lower expression group. CONCLUSIONS: We identified CXCL2, an immune-related chemokine, decreased in hepatocellular carcinoma and the regulation mechanism may be controlled by methylation. Further studies should be warranted to examine if and to what extent the gene is actually suppressed by methylation and if there is a possibility that the CXCL2 axis plays a role for diagnosis and treatment of hepatocellular carcinoma.

Diets containing pomegranate polyphenol and soy isoflavone attenuate contact hypersensitivity in mice.

Contact hypersensitivity (CHS) is frequently used as an animal model for human allergic contact dermatitis (ACD). Diets of pomegranate polyphenols (PPs) or soy isoflavones (SIs) each alleviated CHS symptoms; however, the effect of diets containing a mixture of PPs and SIs on CHS is unclear. We investigated the CHS-inhibitory effects of diets supplemented with a mixture of PPs and SIs at human physiologically relevant doses. Consuming the mixture of PPs and SIs attenuated ear swelling and reduced infiltration of Gr-1-positive cells. Ear swelling decreased in the PP and SI-treated mice compared to the SI-treated mice. The auricle tissues of the PP and SI-fed mice exhibited decreased production of CXCL2 and MCP-5 compared to the SI- and PP-treated mice, respectively. These results suggest that dietary supplementation with a mixture of PPs and SIs may have ACD-preventive effects and may prove more beneficial than supplementation with PPs or SIs alone.

Suppression of methylmercury-induced MIP-2 expression by N-acetyl-L-cysteine in murine RAW264.7 macrophage cell line.

BACKGROUND: The aim of this study is to examine the inflammatory-cytokine expressions in the presence of non-cytotoxic dose of methylmercury (MeHg) in murine macrophages, which is suspected to play an important role in brain damage caused by MeHg exposure. We focused on murine macrophage inflammatory protein-2 (MIP-2), keratinocyte chemoattractant (KC), and monocyte chemoattractant protein-5 (MCP-5). MIP-2 and KC are murine functional homologues of human IL-8 and MCP-5 for human MCP-1. Furthermore, we examined the suppressive effect of N-acetyl-L-cysteine (NAC) on the MeHg-induced inflammatory cytokines. METHODS: In a murine RAW264.7 macrophage cell line, MeHg-induced cytokine expressions were measured using real-time PCR. The suppressive effect of NAC was examined by putting it into the culture medium together with MeHg (co-treatment). In addition, pre- and post-treatment experiments were conducted, in which the cells were treated with NAC before and after MeHg exposure, respectively. RESULTS: Exposure to a non-cytotoxic dose of MeHg up-regulated the mRNA expression of MIP-2 and MCP-5. On the other hand, KC expression was not induced in the presence of MeHg. Effect of MeHg on MIP-2 expressions was suppressed by pre-, co-, and post-treatment with NAC. However, the suppressive effect of pre-treatment was less than the post-treatment, which was as effective as co-treatment. CONCLUSION: In functional homologues of human IL-8, only MIP-2 expression, not KC, was activated in the presence of non-cytotoxic dose of MeHg in murine RAW264.7 macrophage cell line. The more evident inhibitory effect of NAC observed in post-treatment experiments suggests a possible involvement of intracellular activities such as antioxidant effects.

The Fli-1 transcription factor is a critical regulator for controlling the expression of chemokine C-X-C motif ligand 2 (CXCL2).

Mammalian cells produce inflammatory cytokines and chemokines in response to innate immune signals and their expression is tightly regulated. Chemokine (C-X-C motif) ligand 2 (CXCL2), also known as macrophage inflammatory protein 2-alpha (MIP2-alpha), is an inflammatory chemokine belonging to the CXC chemokine family. CXCL2 is chemotactic for neutrophils and elevated expression of CXCL2 is associated with many inflammatory and autoimmune diseases. The Fli-1 gene belongs to the large Ets transcription factor family, whose members regulate a wide variety of cellular functions including the immune response. In this study, we demonstrate that endothelial cells transfected with Fli-1 specific siRNA produce significantly less CXCL2 compared to cells transfected with control siRNA after stimulation by the Toll-like receptor (TLR) 4 ligands, lipopolysaccharide (LPS) and tumor necrosis factor alpha (TNF-α). The production of CXCL2 in endothelial cells stimulated with LPS stimulation is dose-dependent. We found that Fli-1 binds to the CXCL2 promoter as established by Chromatin immunoprecipitation (ChIP) assay. Transient transfection assays show that Fli-1 drives transcription from the CXCL2 promoter in a dose-dependent manner and Fli-1 regulates the expression of CXCL2 largely by directly binding to the promoter. Targeted knockdown and transient transfection experiments suggest that both Fli-1 and the p65 subunit of NF-κB affect the activation of CXCL2 in an additive manner. These results indicate that Fli-1 is a novel, critical transcription factor that regulates the expression of the inflammatory chemokine CXCL2.

Characterization of Innate Immune Responses of Human Endothelial Cells Induced by Porphyromonas gingivalis and Their Derived Outer Membrane Vesicles.

Atherosclerosis, a chronic inflammatory disease of the blood vessels, is one of the most common causes of morbidity and mortality world-wide. Involvement of Porphyromonas gingivalis in atherosclerosis is supported by observations from epidemiological, clinical, immunological, and molecular studies. Previously we reported that P. gingivalis vesicles have a much higher invasive efficiency than their originating cells. Here, we further compare the role of P. gingivalis cells and their vesicles in expression of chemoattractant proteins including CXCL1, CXCL2, and CXCL8, and adhesive molecules such as E-selectin in human umbilical vein endothelial cells (HUVECs). Both P. gingivalis 33277 cells and vesicles were able to up-regulate expression of these molecules, while the vesicles acted as more potent inducers of the inflammatory response associated with the development of atherosclerosis, consequently resulting in significant monocyte adhesion to a monolayer of HUVECs. Interestingly, we found that elevated expression of CXCL8 and E-selectin in endothelial cells induced by P. gingivalis correlated with the invasive ability of P. gingivalis cells and vesicles. Non-invasive bacterial cells and vesicles had no effect on expression of these genes. This study highlights the potential risk of P. gingivalis cells and vesicles in initiation of atherosclerosis and provides a potential target for the development of novel therapeutics against bacteria-associated atherosclerosis.

In vivo induction of neutrophil chemotaxis by secretory aspartyl proteinases of Candida albicans.

Secretory aspartyl proteinases (Saps) of Candida albicans are key virulence traits which cause inflammasome-dependent, aseptic inflammation in a mouse model of vaginitis. In this paper, neutrophil migration in response to Sap2, Sap6 and chemo-attractive products released from Sap-treated vaginal epithelium was measured in vitro, ex vivo and in vivo. Our results show that Sap2 and Sap6 induce neutrophil migration and production of potent chemoattractive chemokines such as IL-8 and MIP-2 by vaginal epithelial cells. Our data suggest that at least part of MIP-2 production depends upon IL-1ß activity. The vaginal fluid of Candida-infected mice contained a heat-labile inhibitor of neutrophil candidacidal activity that was absent from the vaginal fluid of Sap-treated mice. Overall, our data provide additional information on the capacity of C. albicans Saps to cause aseptic vaginal inflammation and highlight the potential role of some chemokines released from vaginal epithelial cells in this phenomenon.

Epithelial Cell-Derived Secreted and Transmembrane 1a Signals to Activated Neutrophils during Pneumococcal Pneumonia.

Airway epithelial cell responses are critical to the outcome of lung infection. In this study, we aimed to identify unique contributions of epithelial cells during lung infection. To differentiate genes induced selectively in epithelial cells during pneumonia, we compared genome-wide expression profiles from three sorted cell populations: epithelial cells from uninfected mouse lungs, epithelial cells from mouse lungs with pneumococcal pneumonia, and nonepithelial cells from those same infected lungs. Of 1,166 transcripts that were more abundant in epithelial cells from infected lungs compared with nonepithelial cells from the same lungs or from epithelial cells of uninfected lungs, 32 genes were identified as highly expressed secreted products. Especially strong signals included two related secreted and transmembrane (Sectm) 1 genes, Sectm1a and Sectm1b. Refinement of sorting strategies suggested that both Sectm1 products were induced predominantly in conducting airway epithelial cells. Sectm1 was induced during the early stages of pneumococcal pneumonia, and mutation of NF-κB RelA in epithelial cells did not diminish its expression. Instead, type I IFN signaling was necessary and sufficient for Sectm1 induction in lung epithelial cells, mediated by signal transducer and activator of transcription 1. For target cells, Sectm1a bound to myeloid cells preferentially, in particular Ly6G(bright)CD11b(bright) neutrophils in the infected lung. In contrast, Sectm1a did not bind to neutrophils from uninfected lungs. Sectm1a increased expression of the neutrophil-attracting chemokine CXCL2 by neutrophils from the infected lung. We propose that Sectm1a is an epithelial product that sustains a positive feedback loop amplifying neutrophilic inflammation during pneumococcal pneumonia.

Lipopolysaccharide Upregulates the Expression of CINC-3 and LIX in Primary NG2 Cells.

Numerous NG2 cells, also called oligodendrocyte progenitor cells (OPCs), exist ubiquitously in the gray and white matter in the adult central nervous system (CNS). Although NG2 cells could become active by upregulation of NG2 expression and hypertrophy or extension of their processes under various neuropathological conditions, their actual role in the brain remains to be illustrated. In view of the fact that the synergy of cytokine and chemokine networks plays an important role in CNS inflammation and immunity, we have assumed that the NG2 cells might take part in brain inflammation and immunity by making a contribution to the pool of cytokines or chemokines. In the current study, NG2-expressing OPCs were prepared from cerebral hemispheres of postnatal day 0 or 1 Sprague-Dawley rats. Our results showed that NG2-expressing OPCs, verified by immunohistological staining of anti-NG2 antibody and anti-platelet-derived growth factor receptor alpha (PDGFRα) antibody, presented binding affinity to lipopolysaccharide (LPS), a commonly used stimulator in a neuroinflammatory model. Using cytokine antibody array, QPCR and ELISA, we have further shown that LPS could upregulate the expression of cytokine induced neutrophil chemoattractant-3 (CINC-3) and LPS induced CXC chemokine (LIX) in primary NG2-expressing OPCs, without the alteration in cell number of NG2-expressing OPCs. In addition, the cells bearing the receptor for these two cytokines included microglia and OPCs. Taken together, our results suggest that NG2-expressing OPCs could response to LPS and may take part in neuroinflammatory process, through secreting cytokines and chemokines to exert an effect on target cells (OPCs and microglia).

Middle Ear Response of Muc5ac and Muc5b Mucins to Nontypeable Haemophilus influenzae.

IMPORTANCE: Chronic otitis media with effusion is characterized by middle ear secretion of mucin glycoproteins, predominantly MUC5B; MUC5AC, the other secretory mucin studied frequently, has also been identified in the middle ear. Emerging evidence suggests a dichotomous role for these mucins in innate immune responses. We hypothesized that MUC5AC is an acute responder and MUC5B is expressed at later time points, reflecting a chronic situation. OBJECTIVE: To determine middle ear regulation of MUC5B and MUC5AC following in vitro bacterial and cytokine exposure. DESIGN, SETTING, AND SAMPLES: An in vitro cell-based model of mucin gene regulation was conducted in a basic science laboratory at a tertiary pediatric hospital. The study was conducted from July 1, 2014, to June 30, 2015; data analysis was performed in July 2015. INTERVENTIONS: Nontypeable Haemophilus influenzae (NTHi) lysates were generated and used to stimulate mouse middle ear epithelial cells (mMEECs) for 2 hours during 3 weeks. MAIN OUTCOMES AND MEASURES: Real-time quantitative polymerase chain reaction, luciferase assays, Western blot assay, and immunofluorescence techniques were performed to determine Muc5ac and Muc5b expression over time, Cxcl2 chemokine response, and nuclear factor-κB activation. Luciferase reporter assays were performed to evaluate specific promoter responses after NTHi exposure. RESULTS: Nontypeable H influenzae lysates (200 µg/mL) drove differential mucin gene activation, with Muc5ac being induced up to 2.04 fold at 24 hours and 2.79 fold at 96 hours (P < .05) and Muc5b being induced only at more long-term points: 1.61 fold at 96 hours, 1.41 fold at 1 week, and 1.53 fold at 3 weeks (P < .05). Although NTHi lysates induced robust, early nuclear factor-κB nuclear translocation with nuclear factor-κB-dependent induction of Cxlc2 expression, the lysates had minimal to no effect on Muc5ac and Muc5b promoter activity. However, in contrast to NTHi lysates, CXCL2 induced significant transcription of both Muc5b and Muc5ac as early as 24 hours. CONCLUSIONS AND RELEVANCE: Nontypeable H influenzae lysates activate differential mucin gene activation in mMEECs. Although Muc5ac is an early response mucin gene, Muc5b appears to react as a chronic response mucin.

Dendritic cell immunoreceptor 1 alters neutrophil responses in the development of experimental colitis.

BACKGROUND: Ulcerative colitis, an inflammatory bowel disease, is associated with the massive infiltration of neutrophils. Although the initial infiltration of neutrophils is beneficial for killing bacteria, it is presumed that persistent infiltration causes tissue damage by releasing antibacterial products as well as inflammatory cytokines. A murine C-type lectin receptor, dendritic cell immunoreceptor 1 (Dcir1), is expressed on CD11b(+) myeloid cells, such as macrophages, dendritic cells and neutrophils. It was reported that Dcir1 is required to maintain homeostasis of the immune system to prevent autoimmunity, but it is also involved in the development of infectious disease resulting in the enhanced severity of cerebral malaria. However, the role of Dcir1 in intestinal immune responses during colitis remains unclear. In this study, we investigated the role of Dcir1 in intestinal inflammation using an experimental colitis model induced with dextran sodium sulfate (DSS). RESULTS: In contrast to wild type (WT) mice, Dcir1 (-/-) mice exhibited mild body weight loss during the course of DSS colitis accompanied by reduced colonic inflammation. Dcir1 deficiency caused a reduced accumulation of neutrophils in the inflamed colon on day 5 of DSS colitis compared with WT mice. Consistently, the production of a neutrophil-attracting chemokine, MIP-2, was also decreased in the Dcir1 (-/-) colon compared with the WT colon on day 5. There were fewer myeloperoxidase-positive neutrophils in the inflamed colon of Dcir1 (-/-) mice than in that of WT mice. Moreover, bone marrow neutrophils from Dcir1 (-/-) mice produced less reactive oxygen species (ROS) by lipopolysaccharide stimulation than those from WT mice. This suggests that Dcir1 deficiency decreases the accumulation of tissue destructive neutrophils during DSS colitis. CONCLUSION: Dcir1 enhances the pathogenesis of DSS colitis by altering neutrophil recruitment and their functions.

Cardiac RNA induces inflammatory responses in cardiomyocytes and immune cells via Toll-like receptor 7 signaling.

We have recently reported that extracellular RNA (exRNA) released from necrotic cells induces cytokine production in cardiomyocytes and immune cells and contributes to myocardial ischemia/reperfusion injury. However, the signaling mechanism by which exRNA exhibits its pro-inflammatory effect is unknown. Here we hypothesize that exRNA directly induces inflammation through specific Toll-like receptors (TLRs). To test the hypothesis, we treated rat neonatal cardiomyocytes, mouse bone marrow-derived macrophages (BMDM), or mouse neutrophils with RNA (2.5-10 µg/ml) isolated from rat cardiomyocytes or the hearts from mouse, rat, and human. We found that cellular RNA induced production of several cytokines such as macrophage inflammatory protein-2 (MIP-2), ILs, TNFα, and the effect was completely diminished by RNase, but not DNase. The RNA-induced cytokine production was partially inhibited in cells treated with TLR7 antagonist or genetically deficient in TLR7. Deletion of myeloid differentiation primary response protein 88 (MyD88), a downstream adapter of TLRs including TLR7, abolished the RNA-induced MIP-2 production. Surprisingly, genetic deletion of TLR3 had no impact on the RNA-induced MIP-2 response. Importantly, extracellular RNA released from damaged cardiomyocytes also induced cytokine production. Finally, mice treated with 50 µg of RNA intraperitoneal injection exhibited acute peritonitis as evidenced by marked neutrophil and monocyte migration into the peritoneal space. Together, these data demonstrate that exRNA of cardiac origin exhibits a potent pro-inflammatory property in vitro and in vivo and that exRNA induces cytokine production through TLR7-MyD88 signaling.

Impaired respiratory function and heightened pulmonary inflammation in episodic binge ethanol intoxication and burn injury.

Clinical data indicate that cutaneous burn injuries covering greater than 10% of the total body surface area are associated with significant morbidity and mortality, in which pulmonary complications, including acute respiratory distress syndrome (ARDS), contribute to nearly half of all patient deaths. Approximately 50% of burn patients are intoxicated at the time of hospital admission, which increases days on ventilators by 3-fold, and doubles the length of hospitalization, compared to non-intoxicated burn patients. The most common drinking pattern in the United States is binge drinking, where an individual rapidly consumes alcoholic beverages (4 for women, 5 for men) in 2 h. An estimated 38 million Americans binge drink, often several times per month. Experimental data demonstrate that a single binge-ethanol exposure, prior to scald injury, impairs innate and adaptive immune responses, thereby enhancing infection susceptibility and amplifying pulmonary inflammation, neutrophil infiltration, and edema, and is associated with increased mortality. Since these characteristics are similar to those observed in ARDS burn patients, our study objective was to determine whether ethanol intoxication and burn injury and the subsequent pulmonary congestion affect physiological parameters of lung function, using non-invasive and unrestrained plethysmography in a murine model system. Furthermore, to mirror young adult binge-drinking patterns, and to determine the effect of multiple ethanol exposures on pulmonary inflammation, we utilized an episodic binge-ethanol exposure regimen, where mice were exposed to ethanol for a total of 6 days (3 days ethanol, 4 days rest, 3 days ethanol) prior to burn injury. Our analyses demonstrate mice exposed to episodic binge ethanol and burn injury have higher mortality, increased pulmonary congestion and neutrophil infiltration, elevated neutrophil chemoattractants, and respiratory dysfunction, compared to burn or ethanol intoxication alone. Overall, our study identifies plethysmography as a useful tool for characterizing respiratory function in a murine burn model and for future identification of therapeutic compounds capable of restoring pulmonary functionality.

Human Mesenchymal Stem (Stromal) Cells Promote the Resolution of Acute Lung Injury in Part through Lipoxin A4.

Previous studies demonstrated that bone marrow-derived mesenchymal stem (stromal) cells (MSCs) reduce the severity of acute lung injury in animal models and in an ex vivo perfused human lung model. However, the mechanisms by which MSCs reduce lung injury are not well understood. In the present study, we tested the hypothesis that human MSCs promote the resolution of acute lung injury in part through the effects of a specialized proresolving mediator lipoxin A4 (LXA4). Human alveolar epithelial type II cells and MSCs expressed biosynthetic enzymes and receptors for LXA4. Coculture of human MSCs with alveolar epithelial type II cells in the presence of cytomix significantly increased the production of LXA4 by 117%. The adoptive transfer of MSCs after the onset of LPS-induced acute lung injury (ALI) in mice led to improved survival (48 h), and blocking the LXA4 receptor with WRW4, a LXA4 receptor antagonist, significantly reversed the protective effect of MSCs on both survival and the accumulation of pulmonary edema. LXA4 alone improved survival in mice, and it also significantly decreased the production of TNF-α and MIP-2 in bronchoalveolar lavage fluid. In summary, these experiments demonstrated two novel findings: human MSCs promote the resolution of lung injury in mice in part through the proresolving lipid mediator LXA4, and LXA4 itself should be considered as a therapeutic for acute respiratory distress syndrome.

Leukotriene B4-leukotriene B4 receptor axis promotes oxazolone-induced contact dermatitis by directing skin homing of neutrophils and CD8⁺ T cells.

Leukotriene B4 (LTB4 ) is a lipid mediator that is rapidly generated in inflammatory sites, and its functional receptor, BLT1, is mostly expressed on immune cells. Contact dermatitis is a common inflammatory skin disease characterized by skin oedema and abundant inflammatory infiltrates, primarily including neutrophils and CD8(+) T cells. The role of the LTB4 -BLT1 axis in contact dermatitis remains largely unknown. In this study, we found up-regulated gene expression of 5-lipoxygenase and leukotriene A4 hydrolase, two critical enzymes for LTB4 synthesis, BLT1 and elevated LTB4 levels in skin lesions of oxazolone (OXA)-induced contact dermatitis. BLT1 deficiency or blockade of LTB4 and BLT1 by the antagonists, bestatin and U-75302, respectively, in the elicitation phase caused significant decreases in ear swelling and skin-infiltrating neutrophils and CD8(+) T cells, which was accompanied by significantly reduced skin expression of CXCL1, CXCL2, interferon-γ and interleukin-1ß. Furthermore, neutrophil depletion during the elicitation phase of OXA-induced contact dermatitis also caused significant decreases in ear swelling and CD8(+) T-cell infiltration accompanied by significantly decreased LTB4 synthesis and gene expression of CXCL2, interferon-γ and interleukin-1ß. Importantly, subcutaneous injection of exogenous LTB4 restored the skin infiltration of CD8(+) T cells in neutrophil-depleted mice following OXA challenge. Collectively, our results demonstrate that the LTB4 -BLT1 axis contributes to OXA-induced contact dermatitis by mediating skin recruitment of neutrophils, which are a major source of LTB4 that sequentially direct CD8(+) T-cell homing to OXA-challenged skin. Hence, LTB4 and BLT1 could be potential therapeutic targets for the treatment of contact dermatitis.

Endothelin receptor B protects granulocyte macrophage colony-stimulating factor mRNA from degradation.

Evidence is lacking on the differential effects of the two therapeutic concepts of endothelin receptor antagonists (ERAs): the blockade of only the endothelin receptor A (ETAR; selective antagonism) versus both ETAR and endothelin receptor B (ETBR; dual blockade). Ambrisentan, a selective ERA, and bosentan, a dual blocker, are both available for therapy. We hypothesized that there are differences in the potential of ERAs to ameliorate inflammatory processes in human airway smooth muscle cells (HASMCs) and aimed to unravel underlying mechanisms. We used HASMC culture, enzyme-linked immunosorbent assay, and quantitative reverse-transcription polymerase chain reaction. Tumor necrosis factor α (TNFα) induced transcription and expression of chemokine (C-X-C motif) ligand 2 (CXCL2), chemokine (C-X-C motif) ligand 3 (CXCL3), granulocyte macrophage colony-stimulating factor (GM-CSF), and matrix metalloproteinase 12 (MMP12) in HASMCs. In concentration-response experiments, bosentan led to a significantly greater reduction of GM-CSF and MMP12 protein release than ambrisentan, whereas there was no significant difference in their effect on GM-CSF and MMP12 mRNA. Both ERAs reduced CXCL3 protein and mRNA equally but had no effect on CXCL2. Blocking mitogen-activated protein kinases revealed that both ETAR and ETBR signal through p38 mitogen-activated protein kinase, but ETBR also signals through extracellular signal-regulated kinase (ERK) 1/2 to induce GM-CSF expression. In the presence of the transcription inhibitor actinomycin D, bosentan, but not ambrisentan, reduced GM-CSF but not MMP12 or CXCL3 mRNA. In conclusion, blockade of each endothelin receptor subtype reduces GM-CSF transcription, but blocking ETBR additionally protects GM-CSF mRNA from degradation via ERK-1/2. Accordingly, blocking both ETAR and ETBR leads to a stronger reduction of TNFα-induced GM-CSF protein expression. This mechanism might be specific to GM-CSF. Our data stress the anti-inflammatory potential of ERA and warrant further investigation of their utility in chronic inflammatory airway diseases.