Interleukin-15 increases neutrophil adhesion onto human respiratory epithelial A549 cells and attracts neutrophils in vivo

Expression of Tumor Suppressor FHIT Is Regulated by the LINC00173-SNAIL Axis in Human Lung Adenocarcinoma

Long non-coding RNAs (lncRNAs) play a critical role in a variety of human diseases such as cancer. Here, to elucidate a novel function of a lncRNA called LINC00173, we investigated its binding partner, target gene, and its regulatory mechanism in lung adenocarcinoma, including the A549 cell line and patients. In the A549 cell line, RNA immunoprecipitation (RIP) assays revealed that LINC00173 efficiently binds to SNAIL. RNA-seq and RT-qPCR analyses revealed that the expression of FHIT was decreased upon LINC00173 depletion, indicating that FHIT is a target gene of LINC00173. Overexpression of SNAIL suppressed and depletion of SNAIL increased the expression of FHIT, indicating that SNAIL negatively regulates FHIT. The downregulation of FHIT expression upon LINC00173 depletion was restored by additional SNAIL depletion, revealing a LINC00173-SNAIL-FHIT axis for FHIT regulation. Data from 501 patients with lung adenocarcinoma also support the existence of a LINC00173-SNAIL-FHIT axis, as FHIT expression correlated positively with LINC00173 (p = 1.75 × 10-6) and negatively with SNAIL (p = 7.00 × 10-5). Taken together, we propose that LINC00173 positively regulates FHIT gene expression by binding to SNAIL and inhibiting its function in human lung adenocarcinoma. Thus, this study sheds light on the LINC00173-SNAIL-FHIT axis, which may be a key mechanism for carcinogenesis and progression in human lung adenocarcinoma.

Impact of gold nanoparticles (AuNPs) in human neutrophils in vitro and in leukocytes attraction in vivo: A sex-based analysis

Some differences exist between the male and female immune systems. Despite this, a sex-based analysis is not frequently performed in most studies. Knowing that inflammation is a common undesired effect observed resulting from nanoparticle (NP) exposure, we investigate here how gold NPs with a primary size of 20 (AuNP20) and 70 nm (AuNP70) will alter the biology of polymorphonuclear neutrophil cells (PMNs) isolated from men and women as well as their potential pro-inflammatory effect in vivo in male and female mice. We found that AuNP20 significantly delay apoptosis only in PMN isolated from men. The production of interleukin (IL)- 8 by PMNs was increased by both AuNPs regardless of sex although significance was only observed in AuNP20-induced PMNs. Using the murine air pouch model of inflammation, AuNPs did not induce a neutrophilic infiltration regardless of sex. In conclusion, AuNPs could differently alter the biology of PMNs according to sex.

Functional responsiveness of in vitro-aged human neutrophils

Elimination of apoptotic neutrophils by macrophages is as a major step for the resolution of inflammation. However, the fate and the cellular functionality of neutrophils aged in the absence of macrophages are not well documented. Herein, freshly isolated human neutrophils were aged for several days in vitro and then stimulated with agonists for determining their cell responsiveness. In vitro-aged neutrophils were still able to generate reactive oxygen species after 48 h, exert phagocytosis after 72 h, and increase their adhesion onto a cell substratum after 48 h. These data demonstrate that a portion of neutrophils cultivated for several days in vitro are still able to exert biological functions. This opens the possibility that, during inflammation, neutrophils may still respond to agonists, a condition that is likely to occur in vivo when they are not efficiently eliminated by efferocytosis.

Interaction between iron oxide nanoparticles (Fe3O4 NPs) and human neutrophils: Evidence that Fe3O4 NPs possess some pro-inflammatory activities

Iron oxide nanoparticles (Fe₃O₄ NPs) are important for different medical applications. However, potential toxicity has been reported and several parameters must still be studied to reach highest therapeutic efficacy with minimal undesired effects. Inflammation is one of the most reported undesired effects of NP exposure in a variety of inflammatory models and conflicting data exist regarding whether Fe₃O₄ NPs possess pro- or anti-inflammatory activities. The aim of this study was to determine the direct effect of Fe₃O₄ NPs on the biology of neutrophil, a key player cell in inflammation. Freshly isolated human neutrophils were incubated in vitro with Fe₃O₄ NPs, and several functions have been studied. Using transmission electronic microscopy, Fe₃O₄ NPs were found to be ingested by neutrophils. These NPs do not induce a respiratory burst by themselves, but they increase the ability of neutrophils to adhere onto human endothelial cells as well as enhance phagocytosis. An antibody array approach revealed that Fe₃O₄ NPs induce the production of some cytokines, including the chemokine IL-8 (CXCL8), which was confirmed by ELISA. Fe₃O₄NPs were found to delay spontaneous neutrophil apoptosis regardless of sex of the donor. Using a pharmacological approach, we demonstrate that Fe₃O₄ NPs delay apoptosis by a de novo protein synthesis-dependent mechanism and via different cell signalling pathways. The data indicate that Fe₃O₄ NPs can alter the biology of human neutrophils and that they possess some pro-inflammatory effects, particularly based on their capacity to delay apoptosis and to induce the production of pro-inflammatory cytokines. Therefore, Fe₃O₄ NPs can regulate inflammation by targeting human neutrophil functions.

Activation of human eosinophils with palladium nanoparticles (Pd NPs): importance of the actin cytoskeleton in Pd NPs-induced cellular adhesion

Palladium (Pd) is known to be released into the environment in the fine and ultrafine (at the nanoscale) airborne particle fractions mainly from automobile catalytic converters leading to an increase human exposure to this noble metal. It was reported that Pd can induce allergic reactions in individuals exposed to it via different ways. Some studies reported an increased number of eosinophils into airways following NP exposure in vivo in rodent models of allergies and inflammation. Knowing the importance of eosinophils in allergies, asthma and other lung diseases, it is surprising to observe that the direct effect of Pd at the nanoscale in eosinophils has been poorly documented. The aim of this study was to determine how Pd NPs will affect the biology of human eosinophils. Characterization of Pd NPs by dynamic light scattering indicates the presence of some aggregates when suspended in diverse solutions used here for the different experiments. Pd NPs did not significantly induce cell necrosis and apoptosis in eosinophils (0.5-150μg/ml) as assessed by trypan blue exclusion assay, flow cytometry after staining with FITC-annexin V and propidium iodide and by morphological observations by optical microscopy. PD NPs, unlike the positive controls, did not induce reactive oxygen species (ROS) but were found to target the actin cytoskeleton, since actin was differently re-located intracellularly when compared to untreated cells as determined by fluorescence microscopy. Clearly, Pd NPs were found to increase adhesion of eosinophils onto human endothelial EA.hy926 cells. Using cytochalasin D, a cell-permeable and potent inhibitor of actin polymerization, this ability to increase adhesion was drastically reversed. Our results indicate that Pd NPs can target the cytoskeleton and increase the adhesion of human eosinophils by an actin-dependent mechanism. These findings show that human eosinophils can be activated by Pd NPs emphasizing the importance of fully investigating how these NPs could alter the biology of human cells involved in allergies, asthma and other lung diseases as well as in various other inflammatory disorders.

WITHDRAWN: Titanium dioxide nanoparticles induce human eosinophil adhesion onto endothelial EA.hy926 cells via activation of phosphoinositide 3-kinase/Akt cell signalling pathway

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Bioactive Antimicrobial Peptides as Therapeutics for Corneal Wounds and Infections

Significance: More than 2 million eye injuries and infections occur each year in the United States that leave civilians and military members with reduced or complete vision loss due to the lack of effective therapeutics. Severe ocular injuries and infections occur in varied settings including the home, workplace, and battlefields. In this review, we discuss the potential of developing antimicrobial peptides (AMPs) as therapeutics for the treatment of corneal wounds and infections for which the current treatment options are inadequate.

Recent Advances: Standard-of-care employs the use of fluorescein dye for the diagnosis of ocular defects and is followed by the use of antibiotics and/or steroids to treat the infection and reduce inflammation. Recent advances for treating corneal wounds include the development of amniotic membrane therapies, wound chambers, and drug-loaded hydrogels. In this review, we will discuss an innovative approach using AMPs with the dual effect of promoting corneal wound healing and clearing infections.

Critical Issues: An important aspect of treating ocular injuries is that treatments need to be effective and administered expeditiously. This is especially important for injuries that occur during combat and in individuals who demonstrate delayed wound healing. To overcome gaps in current treatment modalities, bioactive peptides based on naturally occurring cationic antimicrobial proteins are being investigated as new therapeutics.

Future Directions: The development of new therapeutics that can treat ocular infections and promote corneal wound healing, including the healing of persistent corneal epithelial defects, would be of great clinical benefit.

Role of PTEN in neutrophil extracellular trap formation

NETosis has been associated with a particular mode of cell death although it is still controversial as to what extent autophagy is involved in NETosis. Class I/AKT/mTOR pathway is a key regulator of autophagy. PTEN tumor suppressor gene encodes a dual specificity phosphatase that antagonizes the phosphatidylinositol 3-kinase in class the I/AKT/mTOR pathway. In this study, we investigated the effects of PTEN down-regulation as well as overexpression on NETosis. Our results show that 35% of HL-60 differentiated neutrophil-like cells generated NETs by PMA. The portion of the population that produced NETs in PTEN knockdown HL-60 differentiated neutrophils was 9% and in PTEN overexpressed HL-60 differentiated neutrophils, it was 56%. Our results show that increasing PTEN expression increases NETs formation in neutrophils, and its suppression reduces NETs.

Activation of human neutrophils by Esenbeckia leiocarpa: comparison between the crude hydroalcoholic extract (CHE) and an alkaloid (Alk) fraction

Esenbeckia leiocarpa, a wide spread native Brazilian tree, was reported recently to possess anti-inflammatory effects in vivo, but the mechanisms involved are still not fully understood and its role in neutrophils is poorly documented. The aim of this study was to compare the effects of a crude hydroalcoholic extract (CHE) and an alkaloid-enriched (Alk) fraction obtained from Esenbeckia leiocarpa bark on human neutrophils by investigating the effect of each fraction alone or in a mixture with classical neutrophil agonists. CHE inhibited intracellular reactive oxygen species (ROS) production but increased the extracellular superoxide (O2-) production, while Alk increased the former and also slightly increased O2- production. We found that CHE and Alk also induced phagocytosis accompanied by Syk activation, adhesion and degranulation. However, neither CHE nor Alk potentiated the effect of classical neutrophil agonists, namely the cytokines GM-CSF for phagocytosis and TNF-α for adhesion or N-formyl-methionyl-leucyl-phenylalanine (fMLP) for degranulation. In addition, based on catalase treatment, CHE and Alk induced neutrophil apoptosis by a hydrogen peroxide (H2O2)-dependent mechanism. Since the elimination of apoptotic neutrophils by professional phagocytes is important for the resolution of inflammation, the ability of CHE and Alk to induce neutrophil apoptosis has to be considered as one possible mechanism associated with the anti-inflammatory activity of these fractions previously reported in vivo.

Effects of 1,25-(OH)(2)D (3) on the expressions of vitamin D receptor, STAT5 and cytoskeletal rearrangement in human monocytes incubated with sera from type 2 diabetes patients and diabetic nephropathy patients with uremia

OBJECTIVE

To explore the effects of 1,25-(OH)(2)D(3) and lipopolysaccharide (LPS) plus human recombinant interleukin-15 (IL-15) on expression of vitamin D receptor (VDR) and STAT5, and cytoskeletal rearrangement in human monocytes incubated with sera from type 2 diabetes (T2DM) patients and diabetic nephropathy (DN) patients with uremia.

MATERIALS AND METHODS

Peripheral sera were isolated from healthy volunteers (control group, T2DM patients and DN uremic non-dialysis patients). After incubation with or without 1,25(OH)(2)D(3), THP-1 monocytes were treated with LPS plus IL-15 prior to the collection of cells and supernatants. VDR mRNA transcription was examined by RT-PCR, whilst THP-1 monocytic VDR, STAT5 and p-STAT5 expressions were investigated by Western blotting. Concentrations of IL-6 and monocyte chemoattractant protein-1 (MCP-1) in supernatants were assessed by ELISA. Immunofluorescence and a laser confocal microscopy was used to examine the expression of VDR and cytoskeletal proteins.

RESULTS

Compared to the normal control, LPS and IL-15 down-regulate monocytic VDR expression in T2DM patients and DN uremic patients, whilst with cytoskeletal rearrangement, they up-regulate p-STAT5 expression as well as IL-6 and MCP-1 activity. Such effects could be in part blocked by 1,25-(OH)(2)D(3).

CONCLUSION

The above results suggest that the anti-inflammatory mechanism of 1,25-(OH)(2)D(3) may be related to cytoskeletal proteins, VDR and STAT5 signaling pathway.

Lactobacilli secreting a tumor antigen and IL15 activates neutrophils and dendritic cells and generates cytotoxic T lymphocytes against cancer cells

Lactobacillus rhamnosus GG (LGG) has been used to successfully induce tumor regression in an orthotopic model of bladder cancer. Increased infiltration of neutrophils and macrophages into the tumor mass was observed after therapy. This study evaluates the potential of LGG to induce a directed anti-tumor response. Lactobacilli were modified to secrete the prostate specific antigen (PSA) or IL15 and PSA (IL-15-PSA). Neutrophils and DC were exposed to LGG for 2 h as in clinical therapy for bladder cancer. Recombinant LGG activated neutrophils (elevated MHC class I expression) induced DC maturation (increased expression of CD86, CD80, CD40, MHC II and CD83), T cell proliferation and PSA specific cytotoxic T lymphocytes (CTL) activity. IL15 enhanced direct DC activation of CTL. Thus LGG secreting tumor antigens may activate antigen specific immune responses when instilled intravesically and IL15 could enhance this response.

Neutrophil activation and survival are modulated by interaction with NK cells

It is increasingly evident that neutrophils are able to cross-talk with other leukocytes to shape ongoing inflammatory and immune responses. In this study, we analyzed whether human NK cells may influence the survival and activation of neutrophils under co-culture conditions. We report that NK cells exposed to either IL-15 or IL-18 alone strongly protect the survival of neutrophils via the release of IFNγ and granulocyte macrophage colony-stimulating factor (GM-CSF) plus IFNγ, respectively, and cause a slight up-regulation of neutrophil CD64 and CD11b expression. In comparison, NK cells exposed to both IL-15 and IL-18 show a lesser ability to increase the survival of neutrophils but can more potently up-regulate CD64 and CD11b expression, as well as induce the de novo surface expression of CD69, in neutrophils. Analysis of the events occurring in neutrophil/NK co-cultures exposed to IL-15 plus IL-18 revealed that (i) neutrophil survival is positively affected by NK-derived GM-CSF but negatively influenced by a CD18-dependent neutrophil/NK contact, (ii) NK-derived IFNγ is almost entirely responsible for the induction of CD64, (iii) both soluble factors (primarily GM-CSF) and direct cell-cell contact up-regulate CD11b and CD69 and (iv) NK-derived GM-CSF induces the expression of biologically active heparin-binding EGF-like growth factor (HB-EGF) in neutrophils. Finally, we demonstrate that NK cells can also express HB-EGF when stimulated with either IL-2 or IL-15, yet independently of endogenous GM-CSF. Altogether, our results define a novel interaction within the innate immune system whereby NK cells, by directly modulating neutrophil functions, might contribute to the pathogenesis of inflammatory diseases.

Interleukin (IL)-4 induces leukocyte infiltration in vivo by an indirect mechanism

Interleukin (IL)-4 is a cytokine known mainly for its anti-inflammatory activity. Using the in vivo murine air pouch model, we found that IL-4 significantly increased the number of leukocytes after 9 hours of treatment, consisting mainly of neutrophil (60%) and monocytic (40%) cell populations. Using an antibody array, we found that the expression of several analytes (predominantly CCL2) was increased by IL-4 before the arrival of leukocytes. The IL-4-induced expression of CCL-2 was confirmed by ELISA. Air pouch resident lining cells were harvested and were found to express IL-4Rα. CCL2 mRNA expression was monitored in lining cells, cells isolated from the air pouch skin, in RAW264.7 macrophage and in epithelial Mode-K cells and its expression was increased in response to IL-4 in all conditions. We conclude that IL-4 can attract leukocytes in vivo by an indirect mechanism involving the production of several analytes by, at least, resident cells.

Subcellular expression pattern and role of IL-15 in pneumococci induced lung epithelial apoptosis

Streptococcus pneumoniae is the leading causative agent of community-acquired pneumonia. Induction of apoptosis in pulmonary epithelial cells by bacteria during pneumonia might be harmful to the host. Interleukin-15 (IL-15) has been demonstrated as an effective inhibitor of apoptosis and is expressed in lung epithelium on the mRNA and protein level. Therefore, we characterized the sub-cellular expression pattern of the short and long IL-15 isoforms in lung epithelial cells in vitro as well as its role in pneumococci-related lung epithelial cell apoptosis. We found an expression pattern for both IL-15 signal peptides in the pulmonary epithelial cell lines A549 and Beas-2B. Moreover, a strong co-localization of IL-15 and IL-15Ralpha was detected on cell surfaces. Compared to pro-inflammatory cytokine stimulation, neither IL-15 nor its trimeric receptor complex was up-regulated after pneumococcal infection. However, overexpression of IL-15 isoforms revealed IL-15LSP and IL-15Vkl as inhibitors of pneumococci induced apoptosis in pulmonary epithelial cells. Thus, IL-15 may act as an anti-apoptotic molecule in pneumococci infection, thereby suggesting IL-15 as a benefical cytokine in pulmonary host defense against infection.

Cell-specific interleukin-15 and interleukin-15 receptor subunit expression and regulation in pneumococcal pneumonia--comparison to chlamydial lung infection

Interleukin (IL)-15 has critical impact on the homeostasis and activation of natural killer cells, natural killer T cells, gammadeltaT cells, and CD8(+)T cells, and contributes to antimicrobial defenses particularly at mucosal sites. The respiratory tract comprises a large mucosal surface and harbors significant amounts of lymphocytes, however the expression pattern of IL-15 in the lung and its role in local immune responses are largely unknown. We therefore analyzed the differential expression of IL-15 and the IL-15 receptor (IL-15R) complex in the lungs of mice and demonstrated substantial constitutive expression in bronchial and alveolar epithelial cells, alveolar macrophages, and vascular smooth muscle cells, implicating contribution to pulmonary immune cell homeostasis already under normal conditions. The induction of pneumococcal pneumonia but not the infection with Chlamydophila pneumoniae evoked a significant up-regulation of IL-15 on alveolar macrophages and bronchial epithelial cells, with the latter presenting de-novo expression of IL-15 on their basolateral surface and additional up-regulation of IL-15Ralpha. Moreover, transcriptome analysis as well as semi-quantitative PCR indicated at least partial transcriptional regulation in mice lungs. In conclusion IL-15 is suggested being of functional importance in the pulmonary immune response against pneumococcal pneumonia.

Distinct gene subsets are induced at different time points after human respiratory syncytial virus infection of A549 cells

cDNA microarray technology was applied to time course analysis of differentially expressed genes in A549 cells following human respiratory syncytial virus (HRSV) infection. Both up- and down-regulation of cellular genes were observed in a time-dependent manner. However, gene up-regulation prevailed over gene down-regulation. Virus infectivity was required as UV-inactivated virus failed to up-regulate/down-regulate those genes. At early times post-infection (0-6 h p.i.) 85 genes were up-regulated. Some of those genes were involved in cell growth/proliferation, cellular protein metabolism and cytoskeleton organization. Among the most strongly up-regulated genes at that time were the urokinase plasminogen activator (PLAU) and its receptor (PLAUR), a pleiotropic system involved in many biological processes, including chemotaxis and inflammation. Functionally related genes encoding the alpha- and beta-chains of several integrins were also up-regulated within the first 12 h of infection. Genes up-regulated between 6 and 12 h p.i. included interferon-stimulated genes (ISGs), genes related to oxidative stress and genes of the non-canonical NF-kappaB pathway. At later times, genes involved in the immune response became predominant among the up-regulated genes, most of them being ISGs. Different up-regulation kinetics of cytokine and cytokine-signalling-related genes were also observed. These results highlight the dynamic interplay between the virus and the host cell and provide a general picture of changes in cellular gene expression along the HRSV replicative cycle.

Transcriptional profile of the immune response in the lungs of patients with active tuberculosis

Despite advances in diagnosis and treatment, Mycobacterium tuberculosis causes active disease in about 8 million people worldwide annually. The study of the interplay between the host and the pathogen at the site of infection in human TB may contribute to elucidate the pathogenesis of the disease. In this work, using macroarray technology and real-time PCR, we analyzed the modulation of 847 genes encoding immune-inflammatory mediators in BALF samples of patients affected by active pulmonary TB (PTB) and control patients affected by non-TB diseases. The data show that the PTB milieu contains a complex network of gene activation. Different genes with adhesive properties and involved in tissue repair and fibrosis were modulated. In TB patients, we observed the up-regulation of cytokines, including IFN-gamma and IFN-gamma pathway genes, of several apoptotic genes, and of potent transcriptional activators. These findings can contribute to elucidate the mechanisms of MTB pathogenicity in humans.

Differential Effects of IL-15 and IL-21 in Myeloid (CD11b+) and Lymphoid (CD11b−) Bone Marrow Cells

IL-15 has been found to activate NF-kappaB in various types of cells. However, the role of this transcription factor in IL-15- and IL-21-stimulated murine bone marrow (BM) cells is unclear. In this study, we demonstrated that both IL-15 and IL-21 are capable of delaying BM cell factor deprivation-induced apoptosis, but only IL-15 induced their proliferation. Following separation of BM cells into myeloid (CD11b(+)) and lymphoid (CD11b(-)) cell populations, we found that IL-15, but not IL-21, significantly induced proliferation in both cell populations. Both cytokines significantly delayed apoptosis, but only in CD11b(-) BM cells. IL-15Ralpha, CD122 (IL-2/15Rbeta), and common gamma-chains (CD132) were expressed in both populations, whereas IL-21Ralpha was expressed only in CD11b(-) BM cells. In addition, we demonstrated that IL-15-induced BM cell proliferation was significantly inhibited in NF-kappaBp50(-/-) mice when compared with littermate controls. The ability of IL-15 and IL-21 to delay BM cell apoptosis was slightly inhibited in NF-kappaBp50(-/-) mice, whereas the antiapoptotic effect of LPS was markedly reversed. We conclude that IL-15, but not IL-21, induces BM cell proliferation and that both cytokines delay BM cell apoptosis. These biological activities were preferentially observed in CD11b(-) BM cells. Using NF-kappaBp50(-/-) mice, we demonstrated for the first time that NF-kappaB plays a greater role in IL-15-induced cell proliferation than in IL-15- and IL-21-induced suppression of apoptosis.

Cytokine profile during latent and slowly progressive primary tuberculosis: a possible role for interleukin-15 in mediating clinical disease

Recently, mouse models for latent (LTB) and slowly progressive primary tuberculosis (SPTB) have been established. However, cytokine profiles during the two models are not well established. Using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) we studied the expression levels of interleukin (IL)-2, IL-4, IL-10, IL-12, IL-15, interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha during the course of LTB and SPTB in the lungs and spleens of B6D2F1Bom mice infected with the H37Rv strain of Mycobacterium tuberculosis (Mtb). The results show that, except for IL-4, cytokine expression levels were significantly higher during SPTB than LTB in both the lungs and spleens. During LTB, all the cytokines (except IL-2 in the lungs) had higher expression levels during the initial period of infection both in the lungs and spleens. During SPTB, the expression levels of IL-15 increased significantly from phases 1 to 3 in the lungs. The expression levels of IL-10, IL-12 and IFN-gamma increased significantly from 2 to 3 in the lungs. IL-10 and IL-15 increased significantly from phases 2 to 3, whereas that of TNF-alpha decreased significantly and progressively from phases 1 to 3 in the spleens. Over-expression of proinflammatory cytokines during active disease has been well documented, but factor(s) underlying such over-expression is not known. In the present study, there was a progressive and significant increase in the expression levels of IL-15, together with Th1 cytokines (IL-12 and IFN-gamma) during SPTB but a significant decrease during LTB. IL-15 is known to up-regulate the production of proinflammatory cytokines, IL-1beta, IL-8, IL-12, IL-17, IFN-gamma and TNF-alpha and has an inhibitory effect on activation-induced cell death. IL-15 is known to be involved in many proinflammatory disease states such as rheumatoid arthritis, sarcoidosis, inflammatory bowel diseases, autoimmune diabetes, etc. Our results, together with the above observations, suggest that IL-15 may play an important role in mediating active disease during Mtb infection.