Signal Pathway of Cytokines Produced by Reactive Oxygen Species Generated from Phorbol Myristate Acetate-Stimulated HMC-1 Cells

Administration of ROS-Scavenging Cerium Oxide Nanoparticles Simply Mixed with Autoantigenic Peptides Induce Antigen-Specific Immune Tolerance against Autoimmune Encephalomyelitis

The scavenging ability of cerium oxide nanoparticles (CeNPs) for reactive oxygen species has been intensively studied in the field of catalysis. However, the immunological impact of these particles has not yet been thoroughly investigated, despite intensive research indicating that modulation of the reactive oxygen species could potentially regulate cell fate and adaptive immune responses. In this study, we examined the intrinsic capability of CeNPs to induce tolerogenic dendritic cells via their reactive oxygen species-scavenging effect when the autoantigenic peptides were simply mixed with CeNPs. CeNPs effectively reduced the intracellular reactive oxygen species levels in dendritic cells in vitro, leading to the suppression of costimulatory molecules as well as NLRP3 inflammasome activation, even in the presence of pro-inflammatory stimuli. Subcutaneously administrated PEGylated CeNPs were predominantly taken up by antigen-presenting cells in lymph nodes and to suppress cell maturation in vivo. The administration of a mixture of PEGylated CeNPs and myelin oligodendrocyte glycoprotein peptides, a well-identified autoantigen associated with antimyelin autoimmunity, resulted in the generation of antigen-specific Foxp3+ regulatory T cells in mouse spleens. The induced peripheral regulatory T cells actively inhibited the infiltration of autoreactive T cells and antigen-presenting cells into the central nervous system, ultimately protecting animals from experimental autoimmune encephalomyelitis when tested using a mouse model mimicking human multiple sclerosis. Overall, our findings reveal the potential of CeNPs for generating antigen-specific immune tolerance to prevent multiple sclerosis, opening an avenue to restore immune tolerance against specific antigens by simply mixing the well-identified autoantigens with the immunosuppressive CeNPs.

Dihydromyricetin protects against gentamicin-induced nephrotoxicity via upregulation of renal SIRT3 and PAX2

AIM

Gentamicin-induced nephrotoxicity limits its widespread use as an effective antibacterial agent. Oxidative stress, inflammatory cytokines and apoptotic cell death are major participants in gentamicin-induced nephrotoxicity. We therefore, investigated whether dihydromyricetin (DHM), the antioxidant and anti-inflammatory flavonoid, could protect against the nephrotoxic effects of gentamicin.

METHODS

Male Wistar rats administrated gentamicin (100 mg/kg/day, i.p.) for 8 days. DHM (400 mg/kg, p.o.) was concurrently given with gentamicin for 8 days. Control group received the vehicle of DHM and gentamicin. Histopathological examinations, biochemical measurements and immunohistochemical analyses were done at the end of the study.

KEY FINDINGS

Treatment with DHM improved the gentamicin induced deterioration of renal functions; serum levels of urea, creatinine and cystatin-C as well as urinary levels of Kim-1 and NGAL, the sensitive indicators for early renal damage, were declined. Additionally, DHM abrogated gentamicin-induced changes in kidney morphology. These nephroprotective effects were possibly mediated via decreasing renal gentamicin buildup, activating the antioxidant enzymes GSH, SOD and CAT and decreasing lipid peroxidation and nitric oxide levels. Further, DHM suppressed renal inflammation and apoptotic cell death by decreasing the expression of nuclear factor-kappa B (NF-κB), TNF-alpha and caspase-3. These effects were correlated to the upregulation of renal SIRT3 expression. Also, DHM activated the regeneration and replacement of injured tubular cells with new ones via enhancing PAX2 expression.

SIGNIFICANCE

DHM is a promising therapeutic target that could prevent acute renal injury induced by gentamicin and help renal tubular cells to recover through its antioxidant, anti-inflammatory and antiapoptotic properties.

Enhanced Membrane Fluidization and Cholesterol Displacement by 1-Heptanol Inhibit Mast Cell Effector Functions

Signal transduction by the high-affinity IgE receptor (FcεRI) depends on membrane lipid and protein compartmentalization. Recently published data show that cells treated with 1-heptanol, a cell membrane fluidizer, exhibit changes in membrane properties. However, the functional consequences of 1-heptanol-induced changes on mast cell signaling are unknown. This study shows that short-term exposure to 1-heptanol reduces membrane thermal stability and dysregulates mast cell signaling at multiple levels. Cells treated with 1-heptanol exhibited increased lateral mobility and decreased internalization of the FcεRI. However, this did not affect the initial phosphorylation of the FcεRI-β chain and components of the SYK/LAT1/PLCγ1 signaling pathway after antigen activation. In contrast, 1-heptanol inhibited SAPK/JNK phosphorylation and effector functions such as calcium response, degranulation, and cytokine production. Membrane hyperfluidization induced a heat shock-like response via increased expression of the heat shock protein 70, increased lateral diffusion of ORAI1-mCherry, and unsatisfactory performance of STIM1-ORAI1 coupling, as determined by flow-FRET. Furthermore, 1-heptanol inhibited the antigen-induced production of reactive oxygen species and potentiated stress-induced plasma membrane permeability by interfering with heat shock protein 70 activity. The combined data suggest that 1-heptanol-mediated membrane fluidization does not interfere with the earliest biochemical steps of FcεRI signaling, such as phosphorylation of the FcεRI-β chain and components of the SYK/LAT/PLCγ1 signaling pathway, instead inhibiting the FcεRI internalization and mast cell effector functions, including degranulation and cytokine production.

Caudatin attenuates inflammatory reaction by suppressing JNK/AP-1/NF-κB/caspase-1 pathways in activated HMC-1 cells

One of the interfering factors in Coronavirus disease 2019 (COVID-19) is the cytokine storm, which contributes to hyperinflammation. Mast cells cause COVID-19 hyperinflammation by increasing inflammatory cytokine levels. We investigated whether caudatin, an active compound of Cynanchum auriculatum, could suppress inflammatory response signaling in human mast cell line, HMC-1 cells. Caudatin suppressed activation of c-Jun N-terminal kinase (JNK) and activator protein-1 (AP-1) in HMC-1 cells. Caudatin suppressed nuclear translocation of catalytic subunit (p65) of nuclear factor (NF)-κB by blocking IκBα phosphorylation and degradation. Caudatin also reduced levels of activated-caspase-1 protein and activation of caspase-1. Non-toxic caudatin doses inhibited the mRNA expression and protein synthesis of pro-inflammatory cytokines. A significant finding was that caudatin inhibited JNK/AP-1/NF-κB/caspase-1 signaling molecules, reducing the secretion of inflammatory cytokines. Consequently, we propose that caudatin might be used as a material in health functional foods to alleviate mast cell-mediated inflammatory conditions like COVID-19.

Benefits of Polyphenols and Methylxanthines from Cocoa Beans on Dietary Metabolic Disorders

Theobroma cacao L. is an ancestral cultivated plant which has been consumed by various populations throughout history. Cocoa beans are the basic material occurring in the most consumed product in the world, namely chocolate. Their composition includes polyphenols, methylxanthines, lipids and other compounds that may vary qualitatively and quantitatively according to criteria such as variety or culture area. Polyphenols and methylxanthines are known as being responsible for many health benefits, particularly by preventing cardiovascular and neurodegenerative diseases. Recent studies emphasized their positive role in dietary metabolic disorders, such as diabetes and weight gain. After a brief presentation of cocoa bean, this review provides an overview of recent research activities highlighting promising strategies which modulated and prevented gastro-intestinal metabolism dysfunctions.

Effects of Boswellia Serrata Roxb. and Curcuma longa L. in an In Vitro Intestinal Inflammation Model Using Immune Cells and Caco-2

Inflammatory bowel diseases, which consist of chronic inflammatory conditions of the colon and the small intestine, are considered a global disease of our modern society. Recently, the interest toward the use of herbal therapies for the management of inflammatory bowel diseases has increased because of their effectiveness and favourable safety profile, compared to conventional drugs. Boswellia serrata Roxb. and Curcuma longa L. are amongst the most promising herbal drugs, however, their clinical use in inflammatory bowel diseases is limited and little is known on their mechanism of action. The aim of this work was to investigate the effects of two phytochemically characterized extracts of B. serrata and C. longa in an in vitro model of intestinal inflammation. Their impact on cytokine release and reactive oxygen species production, as well as the maintenance of the intestinal barrier function and on intestinal mucosa immune cells infiltration, has been evaluated. The extracts showed a good protective effect on the intestinal epithelium at 1 µg/mL, with TEER values increasing by approximately 1.5 fold, compared to LPS-stimulated cells. C. longa showed an anti-inflammatory mechanism of action, reducing IL-8, TNF-α and IL-6 production by approximately 30%, 25% and 40%, respectively, compared to the inflammatory stimuli. B. serrata action was linked to its antioxidant effect, with ROS production being reduced by 25%, compared to H₂O₂-stimulated Caco-2 cells. C. longa and B. serrata resulted to be promising agents for the management of inflammatory bowel diseases by modulating in vitro parameters which have been identified in the clinical conditions.

Inhibitory effects of bee venom on mast cell-mediated allergic inflammatory responses

Although bee venom (BV) is a toxin that causes bee stings to be painful, it has been widely used clinically for the treatment of certain immune‑associated diseases. BV has been used traditionally for the treatment of chronic inflammatory diseases. In this regard, the present study analyzed the effect of BV on the regulation of inflammatory mediator production by mast cells and their allergic inflammatory responses in an animal model. HMC‑1 cells were treated with BV prior to stimulation with phorbol‑12‑myristate 13‑acetate plus calcium ionophore A23187 (PMACI). The production of allergy‑associated pro‑inflammatory mediators was examined, and the underlying mechanisms were investigated. Furthermore, to investigate whether BV exhibits anti‑inflammatory effects associated with anti‑allergic effects in vivo, a compound 48/80‑induced anaphylaxis model was used. BV inhibited histamine release, mRNA expression and production of cytokines in the PMACI‑stimulated HMC‑1 cells. Furthermore, the inhibitory effects of BV on mitogen‑activated protein kinase (MAPK), MAPK kinase, signal transducer and activator of transcription 3 (STAT3) and Akt were demonstrated. The present study also investigated the ability of BV to inhibit compound 48/80‑induced systemic anaphylaxis in vivo. BV protected the mice against compound 48/80‑induced anaphylactic‑associated mortality. Furthermore, BV suppressed the mRNA expression levels of pro‑inflammatory cytokines, and suppressed the activation of MAPK and STAT3 in this model. These results provide novel insights into the possible role of BV as a modulator for mast cell‑mediated allergic inflammatory disorders.

Activation of MAPK Is Required for ROS Generation and Exocytosis in HMC-1 Cells Induced by Trichomonas vaginalis-Derived Secretory Products

Trichomonas vaginalis is a flagellated protozoan parasite that causes vaginitis and cervicitis in women and asymptomatic urethritis and prostatitis in men. Mast cells have been reported to be predominant in vaginal smears and vaginal walls of patients infected with T. vaginalis. Mitogen-activated protein kinase (MAPK), activated by various stimuli, have been shown to regulate the transcriptional activity of various cytokine genes in mast cells. In this study, we investigated whether MAPK is involved in ROS generation and exocytotic degranulation in HMC-1 cells induced by T. vaginalis-derived secretory products (TvSP). We found that TvSP induces the activation of MAPK and NADPH oxidase in HMC-1 cells. Stimulation with TvSP induced phosphorylation of MAPK and p47^phox in HMC-1 cells. Stimulation with TvSP also induced up-regulation of CD63, a marker for exocytosis, along the surfaces of human mast cells. Pretreatment with MAPK inhibitors strongly inhibited TvSP-induced ROS generation and exocytotic degranulation. Finally, our results suggest that TvSP induces intracellular ROS generation and exocytotic degranulation in HMC-1 via MAPK signaling.

An in vitro study of anti-inflammatory activity of standardised Andrographis paniculata extracts and pure andrographolide

BACKGROUND

The anti-inflammatory activity of Andrographis paniculata (Acanthaceae), a traditional medicine widely used in Asia, is commonly attributed to andrographolide, its main secondary metabolite. Commercial A. paniculata extracts are standardised to andrographolide content. We undertook the present study to investigate 1) how selective enrichment of andrographolide in commercial A. paniculata extracts affects the variability of non-standardised phytochemical components and 2) if variability in the non-standardised components of the extract affects the pharmacological activity of andrographolide itself.

METHODS

We characterized 12 commercial, standardised (≥30% andrographolide) batches of A. paniculata extracts from India by HPLC profiling. We determined the antioxidant capacity of the extracts using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging, oxygen radical antioxidant capacity (ORAC) and a Folin-Ciocalteu (FC) antioxidant assays. Their anti-inflammatory activity was assessed by assaying their inhibitory effect on the release of tumor necrosis factor alpha (TNF-α) in the human monocytic cell line THP-1.

RESULTS

The andrographolide content in the samples was close to the claimed value (32.2 ± 2.1%, range 27.5 to 35.9%). Twenty-one non-standardised constituents exhibited more than 2-fold variation in HPLC peak intensities in the tested batches. The chlorogenic acid content of the batches varied more than 30-fold. The DPPH free radical scavenging activity varied ~3-fold, the ORAC and FC antioxidant capacity varied ~1.5 fold among batches. In contrast, the TNF-α inhibitory activity of the extracts exhibited little variation and comparison with pure andrographolide indicated that it was mostly due to their andrographolide content.

CONCLUSIONS

Standardised A. paniculata extracts contained the claimed amount of andrographolide but exhibited considerable phytochemical background variation. DPPH radical scavenging activity of the extracts was mostly due to the flavonoid/phenlycarboxylic acid compounds in the extracts. The inhibitory effect of andrographolide on the release of TNF-α was little affected by the quantitative variation of the non-standardised constituents.

A novel role for reciprocal CD30-CD30L signaling in the cross-talk between natural killer and dendritic cells

The interplay between dendritic cells (DCs) and natural killer (NK) cells directs adaptive immune responses. The molecular basis of the cross-talk is largely undefined. Here, we provide evidence for a contribution of CD30 (TNFRSF8) and its ligand CD30L (TNFSF8) expressed on NK cells and DCs, respectively. We demonstrate that CD30-mediated engagement of CD30L induced cytokine secretion from immature DCs via the mitogen-activated protein kinase pathway. Moreover, CD30L engagement promoted differentiation to mature DCs. On the contrary, the engagement of CD30 on NK cells resulted in an NF-κB-dependent release of TNF-α/IFN-γ. These data uncover a novel and unexpected role for CD30/CD30L that contributes to proinflammatory immune responses.

n-3 Long-chain PUFA reduce allergy-related mediator release by human mast cells in vitro via inhibition of reactive oxygen species

Increased n-6 and reduced n-3 long-chain PUFA (LC-PUFA) intake in Western diets may contribute to the increased prevalence of allergic diseases. Key effector cells in allergy are mast cells (MC). The aim of the present study was to investigate the effects of n-6 v. n-3 LC-PUFA on MC phenotype. Human MC lines (LAD2 and HMC-1) were incubated for 24 h with either arachidonic acid (AA, n-6 LC-PUFA) or the n-3 LC-PUFA EPA or DHA. The effects of these three LC-PUFA on degranulation, mediator secretion and reactive oxygen species (ROS) generation were assessed. ROS, mitogen-activated protein kinase (MAPK) or NF-κB inhibitors were used to unravel signalling pathways involved in cytokine secretion. AA, EPA or DHA did not reduce IgE-mediated degranulation by LAD2 cells. However, AA increased PGD₂ and TNF-α secretion by ionomycin/phorbol 12-myristate 13-acetate-stimulated HMC-1, whereas EPA and DHA more prominently inhibited IL-4 and IL-13 secretion. Suppression of IL-4 and IL-13 release by LC-PUFA correlated with reduced ROS generation. IL-4 and IL-13 release by activated HMC-1 was abrogated using ROS inhibitors. Inhibition of MAPK signalling, but not NF-κB, downstream of ROS reduced IL-13 secretion by activated HMC-1. Combined incubation of EPA or DHA with MAPK inhibitors further suppressed IL-13 secretion. In conclusion, the n-6 LC-PUFA AA enhanced pro-inflammatory mediator production by MC, while the n-3 LC-PUFA EPA as well as DHA more effectively suppressed ROS generation and IL-4 and IL-13 release. This suggests that dietary supplementation with EPA and/or DHA may alter the MC phenotype, contributing to a reduced susceptibility to develop and sustain allergic disease.

NOX1 participates in ROS-dependent cell death of colon epithelial Caco2 cells induced by Entamoeba histolytica

Entamoeba histolytica, which causes amebic colitis and occasional liver abscesses in humans, can induce host cell death through apoptosis and necrosis. Recently, we have demonstrated that E. histolytica can induce cell death in neutrophils via diphenyleneiodonium-sensitive NADPH oxidase (NOX)-derived reactive oxygen species (ROS). Although there are enzyme systems similar to the phagocyte NADPH oxidase system in many non-phagocytic cell types, the signaling role of NOX-derived ROS in cell death of human colon epithelial cells induced by E. histolytica remains obscure. Incubation of colon epithelial Caco2 tumor cell lines with amebic trophozoites resulted in intracellular ROS generation and cell death in a caspase-independent manner. Pretreatment with DPI, an inhibitor of NOX, strongly decreased E. histolytica-induced cell death in Caco2 cells. As identified by RT-PCR, NOX1 transcripts were highly expressed in Caco2 cells. siRNA-mediated suppression of NOX1 protein significantly inhibited E. histolytica-induced cell death and ROS response in Caco2 cells. These results suggest that NOX1 participates in the ROS-dependent cell death of colon epithelial cells induced by amebic adhesion during the early phase of intestinal amebiasis.

Cytokine production through PKC/p38 signaling pathways, not through JAK/STAT1 pathway, in mast cells stimulated with IFNgamma

IFNgamma is strongly related to mast cell-associated diseases. There are many reports that IFNgamma inhibits mast cell degranulation. However, inflammatory cytokine production in mast cells stimulated with IFNgamma has not yet been clearly investigated. Therefore, we aimed to investigate the signaling pathways of cytokine production in mast cells stimulated with IFNgamma. Human mast cell line (HMC)-1 or mouse bone marrow-derived mast cells (BMMCs) were stimulated with IFNgamma (100 units) for time periods indicated. Expressions of proteins and mRNAs of cytokines were determined by ELISA and RT-PCR, respectively, activities of MAP kinases, PKC, JAK1/2, and STAT1 on tyrosine 701 and serine 727 by immunoblotting, the DNA-binding activity of the transcription factors by electrophoretic mobility shift assay. IFNgamma-stimulated mast cells showed increase in expressions of proteins and mRNAs of inflammatory cytokines, phosphorylations of MAP kinases, PKCalpha and betaI, JAK1/2, and STAT1 on tyrosine 701 and serine 727. JAK inhibitor or PKC inhibitors inhibited the phosphorylations of p38 kinase, STAT1 on serine 727, and activities of NF-kappaB and AP-1 compared to IFNgamma stimulation alone. These data suggest that IFNgamma-stimulated mast cells induce productions of inflammatory cytokines through PKC/p38/NF-kappaB and AP-1 pathways, not through classical JAK/STAT1 pathway, in both mast cells.

FcepsilonRI- and Fcgamma receptor-mediated production of reactive oxygen species by mast cells is lipoxygenase- and cyclooxygenase-dependent and NADPH oxidase-independent

We investigated the enzymes responsible for FcepsilonRI-dependent production of reactive oxygen species (ROS) and the influence of ROS on mast cell secretory responses. 5-Lipoxygenase (5-LO) was the primary enzyme involved in ROS production by human mast cells (huMC) and mouse bone marrow-derived mast cells (mBMMC) following FcepsilonRI aggregation because incubation with 5-LO inhibitors (AA861, nordihydroguaiaretic acid, zileuton) but not a flavoenzyme inhibitor (diphenyleneiodonium) completely abrogated Ag-induced dichlorodihydrofluorescein (DCF) fluorescence. Furthermore, 5-LO-deficient mBMMC had greatly reduced FcepsilonRI-dependent DCF fluorescence compared with wild type mBMMC or those lacking a functional NADPH oxidase (i.e., gp91(phox)- or p47(phox)-deficient cells). A minor role for cyclooxygenase (COX)-1 in FcepsilonRI-dependent ROS production was demonstrated by inhibition of Ag-mediated DCF fluorescence by a COX-1 inhibitor (FR122047) and reduced DCF fluorescence in COX-1-deficient mBMMC. Complete abrogation of FcepsilonRI-dependent ROS production in mast cells had no effect on degranulation or cytokine secretion. In response to the NADPH oxidase-stimulating agents including PMA, mBMMC and huMC produced negligible ROS. IgG-coated latex beads did stimulate ROS production in huMC, and in this experiment 5-LO and COX again appeared to be the enzymatic sources of ROS. In contrast, IgG-coated latex bead-induced ROS production in human polymorphonuclear leukocytes occurred by the NADPH oxidase pathway. Thus mBMMC and huMC generate ROS by 5-LO and COX-1 in response to FcepsilonRI aggregation; huMC generate ROS upon exposure to IgG-coated latex beads by 5-LO and COX; and ROS appear to have no significant role in FcepsilonRI-dependent degranulation and cytokine production.

Reactive oxygen species produced up- or downstream of calcium influx regulate proinflammatory mediator release from mast cells: role of NADPH oxidase and mitochondria

Earlier studies have demonstrated that mast cells produce reactive oxygen species (ROS), which play a role in regulating Ca(2+) influx, while in other cell types ROS are produced in a Ca(2+)-dependent manner. We sought to determine whether ROS are produced downstream of the extracellular Ca(2+) entry in mast cells. Thapsigargin (TG), a receptor-independent agonist, could evoke a robust burst of intracellular ROS. However, this response was distinct from the antigen-induced burst of ROS with respect to time course and dependence on Ca(2+) and phosphatidylinositol-3-kinase (PI3K). The antigen-induced ROS generation occurred immediately, while the TG-induced ROS generation occurred with a significant lag time (~2 min). Antigen but not TG caused extracellular release of superoxide (O(2)(*-))/hydrogen peroxide (H(2)O(2)), which was blocked by diphenyleneiodonium, apocynin, and wortmannin. A capacitative Ca(2+) entry resulted in the generation of O(2)(*-) in the mitochondria in a PI3K-independent manner. Blockade of ROS generation inhibited TG-induced mediator release. Finally, when used together, antigen and TG evoked the release of leukotriene C(4), tumor necrosis factor-alpha, and interleukin-13 as well as ROS generation synergistically. These results suggest that ROS produced upstream of Ca(2+) influx by NADPH oxidase and downstream of Ca(2+) influx by the mitochondria regulate the proinflammatory response of mast cells.

The role of reactive oxygen species and nitric oxide in mast cell-dependent inflammatory processes

Reactive oxygen species (ROS) and reactive nitrogen oxide species (RNOS), including nitric oxide, are produced in cells by a variety of enzymatic and non-enzymatic mechanisms. At high levels, both types of oxidants are used to kill ingested organisms within phagocytes. At low levels, RNOS may diffuse outside cells where they impact the vasculature and nervous system. Recent evidence suggests that low levels of ROS produced within cells are involved in cell signaling. Along with these physiological roles, many pathological conditions exist where detrimental high-level ROS and RNOS are produced. Many situations in which ROS/RNOS are associated also involve mast cell activation. In innate immunity, such mast cells are involved in the immune response toward pathogens. In acquired immunity, activation of mast cells by cross-linking of receptor-bound immunoglobulin E causes the release of mediators involved in the allergic inflammatory response. In this review, we describe the principle pathways for ROS and RNOS generation by cells and discuss the existence of such pathways in mast cells. In addition, we examine the evidence for a functional role for ROS and RNOS in mast cell secretory responses and discuss evidence for a direct relationship between ROS, RNOS, and mast cells in mast cell-dependent inflammatory conditions.

Involvement of innate immunity in the pathogenesis of chronic hepatitis C in children

The aim of the study was to assess the role of selected elements of innate immunity in the pathogenesis of chronic hepatitis C in children. The study comprised 20 children with chronic hepatitis C (group 1), nine healthy hepatitis C virus (HCV) seropositive children (group 2) and 18 healthy children (control group). We evaluated the expression of Toll-like receptor (TLR)2 and TLR4 on peripheral blood neutrophils, and generation of interleukin (IL)-8, IL-10, IL-12 and reactive oxygen species (ROS) by neutrophils. The performed tests demonstrated higher expression of TLR2 and TLR4 on stimulated neutrophils and of TLR4 on non-stimulated neutrophils in group 1 in comparison to HCV seropositive children and controls. In group 1, the expression of TLR2 after granulocyte colony-stimulating factor (GCSF) stimulation showed positive correlation with alanine aminotransferase and asparate aminotransferase activities, while the expression of TLR2 without stimulation and of TLR4 after GCSF stimulation also correlated with necrosis. IL-12 generation by lipopolysachcharide-stimulated neutrophils was higher in group 1 versus controls. In group 1, maximum chemiluminescence (CL) without pre-activation, both spontaneous and after formyl-methionyl-leucyl-phenylanine and phorbol-myristate-acetate (PMA) stimulation, was significantly lower than in the controls. CL after tumour necrosis factor-alpha pre-activation and PMA stimulation was still lower than in the controls, however, after opsonized zymosane stimulation it was significantly higher than in the controls. Our studies suggest the involvement of neutrophils in the pathogenesis of chronic hepatitis C in children. Neutrophils demonstrate increased expression of TLR2 and TLR4 (correlating with the features of hepatocytic damage and intensification of necrosis), inhibition of oxygen metabolism, and after TNF-alpha pre-activation higher ability to produce ROS.

The role of the NADPH oxidase complex, p38 MAPK, and Akt in regulating human monocyte/macrophage survival

M-CSF induces PI 3-kinase activation, resulting in reactive oxygen species (ROS) production. Previously, we reported that ROS mediate macrophage colony-stimulating factor (M-CSF)-induced extracellular regulated kinase (Erk) activation and monocyte survival. In this work, we hypothesized that M-CSF-stimulated ROS products modulated Akt1 and p38 activation. Furthermore, we sought to clarify the source of these ROS and the role of ROS and Akt in monocyte/macrophage survival. Macrophages from p47(phox-/-) mice, lacking a key component of the NADPH oxidase complex required for ROS generation, had reduced cell survival and Akt1 and p38 mitogen-activated protein kinase (MAPK) phosphorylation compared with wild-type macrophages in response to M-CSF stimulation, but had no difference in M-CSF-stimulated Erk. To understand how ROS affected monocyte survival and signaling, we observed that NAC and DPI decreased cell survival and Akt1 and p38 MAPK phosphorylation. Using bone marrow-derived macrophages from mice expressing constitutively activated Akt1 (Myr-Akt1) or transfecting Myr-Akt1 constructs into human peripheral monocytes, we concluded that Akt is a positive regulator of monocyte survival. Moreover, the p38 MAPK inhibitor, SB203580, inhibited p38 activity and M-CSF-induced monocyte survival. These findings demonstrate that ROS generated from the NADPH oxidase complex contribute to monocyte/macrophage survival induced by M-CSF via regulation of Akt and p38 MAPK.

Role of oxidative stress in remodeling of the myocardial microcirculation in hypertension

OBJECTIVE

We tested the hypothesis that in early hypertension (HT), increased oxidative stress leads to myocardial microvascular remodeling.

METHODS AND RESULTS

Pigs were studied after a 12-week observation: normal (n=8), untreated renovascular HT (n=8), or HT+chronic antioxidant supplementation (HT+A, n=6). Left ventricular muscle mass (LVMM) and myocardial blood flow (MBF) reserve were determined using electron beam computer tomography (CT), and the spatial density and tortuousity of myocardial microvessels (<500 microm) was then measured in myocardial samples with micro-CT. Myocardial microvascular morphology, oxidative stress, inflammation, and growth factor expression were determined in vitro. HT and HT+A had similarly increased arterial pressure and LVMM, but only HT showed impaired MBF response to adenosine. Compared with normal, HT had increased spatial density of myocardial microvessels, which was preserved in HT+A (111.8+/-7.8, 166.3+/-15.7, and 106.4+/-6.1 vessels per cm2, respectively). HT also showed microvascular wall thickening, increased systemic and tissue oxidative stress, inflammation, and expression of vascular endothelial growth factor and its receptor Flk-1, most of which were attenuated by antioxidants.

CONCLUSIONS

Myocardial microvascular remodeling in early HT is accompanied by tissue oxidative stress, inflammation, and altered growth factor expression, and attenuated by antioxidant intervention. This study underscores a role of increased oxidative stress in modulating myocardial microvascular architecture in early HT.