Myeloperoxidase mediates neutrophil activation by association with CD11b/CD18 integrins

Neutrophil myeloperoxidase diminishes the toxic effects and mortality induced by lipopolysaccharide

Neutrophils have crucial antimicrobial functions but are also thought to contribute to tissue injury upon exposure to bacterial products, such as lipopolysaccharide (LPS). To study the role of neutrophils in LPS-induced endotoxemia, we developed a new mouse model, PMNDTR mice, in which injection of diphtheria toxin induces selective neutrophil ablation. Using this model, we found, surprisingly, that neutrophils serve to protect the host from LPS-induced lethal inflammation. This protective role was observed in conventional and germ-free animal facilities, indicating that it does not depend on a particular microbiological environment. Blockade or genetic deletion of myeloperoxidase (MPO), a key neutrophil enzyme, significantly increased mortality after LPS challenge, and adoptive transfer experiments confirmed that neutrophil-derived MPO contributes importantly to protection from endotoxemia. Our findings imply that, in addition to their well-established antimicrobial properties, neutrophils can contribute to optimal host protection by limiting the extent of endotoxin-induced inflammation in an MPO-dependent manner.

Peripheral leukocyte and endometrium molecular biomarkers of inflammation and oxidative stress are altered in peripartal dairy cows supplemented with Zn, Mn, and Cu from amino acid complexes and Co from Co glucoheptonate

Background

Immune dysfunction and a higher risk of uterine infections are characteristics of the transition into lactation in dairy cows. The supply of complexed trace minerals, which are more bioavailable, could help overcome the greater needs of these nutrients in tissues around parturition and early lactation.

Results

Twenty Holstein cows received an oral bolus with a mix of inorganic trace minerals (INO) or complexed trace minerals (AAC) to achieve 75, 65, 11, and 1 ppm supplemental Zn, Mn, Cu, and Co, respectively, in the total diet dry matter from -30 d through +30 d relative to parturition. Blood for polymorphonuclear leukocyte (PMNL) isolation was collected at -30, -15, +10, and + 30 d relative to parturition, whereas endometrium biopsies were performed at +14 and +30 d. Feeding AAC led to greater PMNL expression of genes related with inflammation response (DDX58), oxidative stress response (MPO), eicosanoid metabolism (PLA2G4A and ALOX5AP), transcription regulation (PPARG), and cellular adhesion (TLN1). The upregulation by AAC in endometrium of genes related with inflammation response (TLR2, TLR4, NFKB1, TNF, IL6, IL1B, IL10, IL8), prostaglandin synthesis (PTGS2, PTGES), and antioxidant responses (NFE2L2, SOD1) indicated a faster remodeling of uterine tissue and potentially greater capacity to control a local bacterial invasion.

Conclusions

Data indicate that trace mineral supplementation from amino acid complexes improves PMNL activity and allows the prompt recovery of uterine tissue during early lactation. As such, the benefits of complexed trace minerals extend beyond an improvement of liver function and productive performance.

Electronic supplementary material

The online version of this article (doi:10.1186/s40104-017-0163-7) contains supplementary material, which is available to authorized users.

Role of the Vanins-Myeloperoxidase Axis in Colorectal Carcinogenesis

The presence of chronic inflammation in the colonic mucosa leads to an increased risk of cancer. Among proteins involved in the regulation of mucosal inflammation and that may contribute both to structural damage of the intestinal mucosa and to intestinal carcinogenesis, there are myeloperoxidase (MPO) and vanins. The infiltration of colonic mucosa by neutrophils may promote carcinogenesis through MPO, a key enzyme contained in the lysosomes of neutrophils that regulates local inflammation and the generation of reactive oxygen species (ROS) and mutagenic species. The human vanin gene family consists of three genes: vanin-1, vanin-2 and vanin-3. All vanin molecules are pantetheinases, that hydrolyze pantetheine into pantothenic acid (vitamin B5), and cysteamine, a sulfhydryl compound. Vanin-1 loss confers an increased resistance to stress and acute intestinal inflammation, while vanin-2 regulates adhesion and transmigration of activated neutrophils. The metabolic product of these enzymes has a prominent role in the inflammation processes by affecting glutathione levels, inducing ulcers through a reduction in mucosal blood flow and oxygenation, decreasing local defense mechanisms, and in carcinogenesis by damaging DNA and regulating pathways involved in cell apoptosis, metabolism and growth, as Nrf2 and HIF-1α.

Critical role for complement receptor C5aR2 in the pathogenesis of renal ischemia-reperfusion injury

The complement system, and specifically C5a, is involved in renal ischemia-reperfusion (IR) injury. The 2 receptors for complement anaphylatoxin C5a (C5aR1 and C5aR2) are expressed on leukocytes as well as on renal epithelium. Extensive evidence shows that C5aR1 inhibition protects kidneys from IR injury; however, the role of C5aR2 in IR injury is less clear as initial studies proposed the hypothesis that C5aR2 functions as a decoy receptor. By Using wild-type, C5aR1^-/-, and C5aR2^-/- mice in a model of renal IR injury, we found that a deficiency of either of these receptors protected mice from renal IR injury. Surprisingly, C5aR2^-/- mice were most protected and had lower creatinine levels and reduced acute tubular necrosis. Next, an in vivo migration study demonstrated that leukocyte chemotaxis was unaffected in C5aR2^-/- mice, whereas neutrophil activation was reduced by C5aR2 deficiency. To further investigate the contribution of renal cell-expressed C5aR2 vs leukocyte-expressed C5aR2 to renal IR injury, bone marrow chimeras were created. Our data show that both renal cell-expressed C5aR2 and leukocyte-expressed C5aR2 mediate IR-induced renal dysfunction. These studies reveal the importance of C5aR2 in renal IR injury. They further show that C5aR2 is a functional receptor, rather than a decoy receptor, and may provide a new target for intervention.-Poppelaars, F., van Werkhoven, M. B., Kotimaa, J., Veldhuis, Z. J., Ausema, A., Broeren, S. G. M., Damman, J., Hempel, J. C., Leuvenink, H. G. D., Daha, M. R., van Son, W. J., van Kooten, C., van Os, R. P., Hillebrands, J.-L., Seelen, M. A. Critical role for complement receptor C5aR2 in the pathogenesis of renal ischemia-reperfusion injury.

A fluorescent homogeneous assay for myeloperoxidase measurement in biological samples. A positive correlation between myeloperoxidase-generated HOCl level and oxidative status in STZ-diabetic rats

Myeloperoxidase (MPO) is a key enzyme derived from leukocytes which is associated with the initiation and progression of many inflammatory diseases. Increased levels of MPO may contribute to cellular dysfunction and tissues injury by producing highly reactive oxidants such as hypochlorous acid (HOCl). Myeloperoxidase-generated HOCl is therefore considered as a relevant biomarker of oxidative stress-related damage and its quantitation is of great importance to the study of disease progression. In this context, the current study describes a rapid, sensitive and homogeneous fluorescence-based method for detecting the MPO chlorination activity in biological samples. This assay utilizes 7-hydroxy-2-oxo-2H-chromene-8-carbaldehyde oxime as a selective probe for HOCl detection, and is adapted to 96-well microplates to allow high-throughput quantitation of active MPO. The ability of the method to monitor HOCl release was further investigated in hyperglycemic streptozotocin-treated diabetic rats. The data proved that the present assay has a reliable performance when quantitating the active MPO in the plasma of diabetic animals, a feature of inflammatory disease found concomitant with an elevation of protein carbonyls levels and lipid peroxidation and which was negatively correlated with the ratio of reduced-to-oxidized glutathione.

Mycobacterium tuberculosis Cell Wall Fragments Released upon Bacterial Contact with the Human Lung Mucosa Alter the Neutrophil Response to Infection

In 2016, the World Health Organization reported that one person dies of tuberculosis (TB) every 21 s. A host environment that Mycobacterium tuberculosis (M.tb) finds during its route of infection is the lung mucosa bathing the alveolar space located in the deepest regions of the lungs. We published that human lung mucosa, or alveolar lining fluid (ALF), contains an array of hydrolytic enzymes that can significantly alter the M.tb surface during infection by cleaving off parts of its cell wall. This interaction results in two different outcomes: modifications on the M.tb cell wall surface and release of M.tb cell wall fragments into the environment. Typically, one of the first host immune cells at the site of M.tb infection is the neutrophil. Neutrophils can mount an extracellular and intracellular innate immune response to M.tb during infection. We hypothesized that exposure of neutrophils to ALF-induced M.tb released cell wall fragments would prime neutrophils to control M.tb infection better. Our results show that ALF fragments activate neutrophils leading to an increased production of inflammatory cytokines and oxidative radicals. However, neutrophil exposure to these fragments reduces production of chemoattractants (i.e., interleukin-8), and degranulation, with the subsequent reduction of myeloperoxidase release, and does not induce cytotoxicity. Unexpectedly, these ALF fragment-derived modulations in neutrophil activity do not further, either positively or negatively, contribute to the intracellular control of M.tb growth during infection. However, secreted products from neutrophils primed with ALF fragments are capable of regulating the activity of resting macrophages. These results indicate that ALF-induced M.tb fragments could further contribute to the control of M.tb growth and local killing by resident neutrophils by switching on the total oxidative response and limiting migration of neutrophils to the infection site.

Capsaicin prevents degeneration of dopamine neurons by inhibiting glial activation and oxidative stress in the MPTP model of Parkinson's disease

The effects of capsaicin (CAP), a transient receptor potential vanilloid subtype 1 (TRPV1) agonist, were determined on nigrostriatal dopamine (DA) neurons in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease (PD). The results showed that TRPV1 activation by CAP rescued nigrostriatal DA neurons, enhanced striatal DA functions and improved behavioral recovery in MPTP-treated mice. CAP neuroprotection was associated with reduced expression of proinflammatory cytokines (tumor necrosis factor-α and interleukin-1β) and reactive oxygen species/reactive nitrogen species from activated microglia-derived NADPH oxidase, inducible nitric oxide synthase or reactive astrocyte-derived myeloidperoxidase. These beneficial effects of CAP were reversed by treatment with the TRPV1 antagonists capsazepine and iodo-resiniferatoxin, indicating TRPV1 involvement. This study demonstrates that TRPV1 activation by CAP protects nigrostriatal DA neurons via inhibition of glial activation-mediated oxidative stress and neuroinflammation in the MPTP mouse model of PD. These results suggest that CAP and its analogs may be beneficial therapeutic agents for the treatment of PD and other neurodegenerative disorders that are associated with neuroinflammation and glial activation-derived oxidative damage.

Neutrophil Microparticles Deliver Active Myeloperoxidase to Injured Mucosa To Inhibit Epithelial Wound Healing

Neutrophil (PMN) infiltration of the intestinal mucosa often leads to severe epithelial injury; however, how this process occurs is unclear. This article describes a novel mechanism whereby membrane-derived microparticles released by tissue infiltrating PMNs (PMN-MPs) serve as shuttles to protect and deliver active mediators to locally modulate cellular function during inflammation. Specifically, myeloperoxidase (MPO), which is abundantly expressed in PMN azurophilic granules and is used for microbial killing, was found to be mobilized to the PMN surface and subsequently released in association with PMN-MPs upon PMN activation and binding to intestinal epithelial cells (IECs). The enzymatic activity of PMN-MP-associated MPO was enhanced compared with soluble protein, leading to potent inhibition of wound closure following PMN-MP binding to IECs. Importantly, localized microinjection of PMN-MPs into wounded colonic mucosa was sufficient to impair epithelial wound healing in vivo. PMN-MP/MPO-dependent inhibition of IEC wound healing was due to impaired IEC migration and proliferation, resulting from impeded actin dynamics, cell spreading, and cell cycle arrest. Thus, our findings provide new insight into mechanisms governing PMN-induced tissue injury and implicate PMN-MPs and MPO as important regulators of cellular function.

The Pivotal Role of CXCR7 in Stabilization of the Pulmonary Epithelial Barrier in Acute Pulmonary Inflammation

Acute pulmonary inflammation is still a frightening complication in intensive care units and has a high mortality. Specific treatment is not available, and many details of the pathomechanism remain unclear. The recently discovered chemokine receptor CXCR7 and its ligand stromal cell-derived factor (SDF)-1 are known to be involved in inflammation. We chose to investigate the detailed role of CXCR7 in a murine model of LPS inhalation. Inflammation increased pulmonary expression of CXCR7, and the receptor was predominantly expressed on pulmonary epithelium and on polymorphonuclear neutrophil (PMNs) after transepithelial migration into the alveolar space. Specific inhibition of CXCR7 reduced transepithelial PMN migration by affecting the expression of adhesion molecules. CXCR7 antagonism reduced the most potent PMN chemoattractants CXCL1 and CXCL2/3. After inhibiting CXCR7, NF-κB phosphorylation was reduced in lungs of mice, tight junction formation increased, and protein concentration in the bronchoalveolar lavage diminished, showing the impact of CXCR7 on stabilizing microvascular permeability. In vitro studies with human cells confirmed the pivotal role of CXCR7 in pulmonary epithelium. Immunofluorescence of human lungs confirmed our in vivo data and showed an increase of the expression of CXCR7 in pulmonary epithelium. Highlighting the clinical potential of CXCR7 antagonism, nebulization of the agent before and after the inflammation showed impressive anti-inflammatory effects. Additional CXCR7 inhibition potentiated the effect of SDF-1 antagonism, most probably by downregulating SDF-1 and the second receptor of the chemokine (CXCR4) expression. In conclusion, our data identified the pivotal role of the receptor CXCR7 in pulmonary inflammation with a predominant effect on the pulmonary epithelium and PMNs.

Myeloperoxidase Attenuates Pathogen Clearance during Plasmodium yoelii Nonlethal Infection

Myeloperoxidase (MPO), a leukocyte-derived enzyme mainly secreted by activated neutrophils, is known to be involved in the immune response during bacterial and fungal infection and inflammatory diseases. Nevertheless, the role of MPO in a parasitic disease like malaria is unknown. We hypothesized that MPO contributes to parasite clearance. To address this hypothesis, we used Plasmodium yoelii nonlethal infection in wild-type and MPO-deficient mice as a murine malaria model. We detected high MPO plasma levels in wild-type mice with Plasmodium yoelii infection. Unexpectedly, infected MPO-deficient mice did not show increased parasite loads but were able to clear the infection more rapidly than wild-type mice. Additionally, the presence of neutrophils at the onset of infection seemed not to be essential for the control of the parasitemia. The effect of decreased parasite levels in MPO-deficient mice was absent from animals lacking mature T and B cells, indicating that this effect is most likely dependent on adaptive immune response mechanisms. Indeed, we observed increased gamma interferon and tumor necrosis factor alpha production by T cells in infected MPO-deficient mice. Together, these results suggest that MPO modulates the adaptive immune response during malaria infection, leading to an attenuated parasite clearance.

Co-Activation of Th17 and Antibody Responses Provides Efficient Protection against Mucosal Infection by Group A Streptococcus

Conserved protein antigens among serotypes of group A Streptococcus pyogenes (GAS) have been focused for vaccine development because of the diversity of GAS serotypes and risks of autoimmunity post-GAS infection. Precise delineation of protective immune response to each of GAS antigens is critical for vaccine efficacy and safety. We recently reported that immunization with SrtA of GAS provides Th17-dependent clearance of heterologous serotypes of GAS in NALT. SCPA is a surface virulence molecule of GAS and known to induce antibody-mediated protection against GAS. We hypothesized that co-immunization with SrtA and SCPA would provide more efficient protection by eliciting combined Th17 and antibody responses. The present study showed that mice that were intranasally co-immunized with SrtA/SCPA cleared GAS more efficiently than the mice that were immunized with either SrtA or SCPA individually, and as efficient as the mice that experienced repeated GAS infections. The co-immunization induced Th17 and robust SCPA antibody responses, accompanied by a rapid influx of neutrophils and high myeloperoxidase activity in NALT, suggesting that simultaneous induction of mucosal Th17 and neutralizing antibody responses offers more effective GAS elimination through rapid infiltration and activation of neutrophils. Moreover, Th17 response was strongly induced in mice that experienced repeated GAS-infection and maintained at a high level even after the bacteria were cleared; whereas, it was moderately induced and promptly returned to baseline following bacterial elimination in SrtA/SCPA co-immunized mice. Additional results showed that the survival rate of systemic challenge was significantly higher in infection experienced than in co-immunized mice, indicating that more immune elements are required for protection against systemic than mucosal GAS infection.

A keratan sulfate disaccharide prevents inflammation and the progression of emphysema in murine models

Emphysema is a typical component of chronic obstructive pulmonary disease (COPD), a progressive and inflammatory airway disease. However, no effective treatment currently exists. Here, we show that keratan sulfate (KS), one of the major glycosaminoglycans produced in the small airway, decreased in lungs of cigarette smoke-exposed mice. To confirm the protective effect of KS in the small airway, a disaccharide repeating unit of KS designated L4 ([SO₃^--6]Galβ1-4[SO₃^--6]GlcNAc) was administered to two murine models: elastase-induced-emphysema and LPS-induced exacerbation of a cigarette smoke-induced emphysema. Histological and microcomputed tomography analyses revealed that, in the mouse elastase-induced emphysema model, administration of L4 attenuated alveolar destruction. Treatment with L4 significantly reduced neutrophil influx, as well as the levels of inflammatory cytokines, tissue-degrading enzymes (matrix metalloproteinases), and myeloperoxidase in bronchoalveolar lavage fluid, suggesting that L4 suppressed inflammation in the lung. L4 consistently blocked the chemotactic migration of neutrophils in vitro. Moreover, in the case of the exacerbation model, L4 inhibited inflammatory cell accumulation to the same extent as that of dexamethasone. Taken together, L4 represents one of the potential glycan-based drugs for the treatment of COPD through its inhibitory action against inflammation.

Contribution of myeloperoxidase and inducible nitric oxide synthase to pathogenesis of psoriasis

INTRODUCTION

Histological changes of psoriasis include invasion of neutrophils into the epidermis and formation of Munro abscesses in the epidermis. Neutrophils are the predominant white blood cells in circulation when stimulated; they discharge the abundant myeloperoxidase (MPO) enzyme that uses hydrogen peroxide to oxidize chloride for killing ingested bacteria.

AIM

To investigate the contribution of neutrophils to the pathogenesis of psoriasis at the blood and tissue levels through inducible nitric oxide synthase (iNOS) and MPO.

MATERIAL AND METHODS

A total of 50 adult patients with a chronic plaque form of psoriasis and 25 healthy controls were enrolled to this study. Serum MPO and iNOS levels were measured using ELISA method. Two biopsy specimens were taken in each patient from the center of the lesion and uninvolved skin. Immunohistochemistry was performed for MPO and iNOS on both normal and psoriasis vulgaris biopsies.

RESULTS

While a significant difference between serum myeloperoxidase levels were detected, a similar statistical difference between participants in the serum iNOS levels was not found. In immunohistochemistry, intensely stained leukocytes with MPO and intensely staining with iNOS in psoriatic skin was observed.

CONCLUSIONS

Neutrophils in psoriasis lesions are actively producing MPO and this indirectly triggers the synthesis of iNOS. Targeting of MPO or synthesis of MPO in the lesion area may contribute to development of a new treatment option.

Extracellular Superoxide Dismutase Enhances Recruitment of Immature Neutrophils to the Liver

Listeria monocytogenes is a Gram-positive intracellular pathogen that causes spontaneous abortion in pregnant women, as well as septicemia, meningitis, and gastroenteritis, primarily in immunocompromised individuals. Although L. monocytogenes can usually be effectively treated with antibiotics, there is still around a 25% mortality rate with individuals who develop clinical listeriosis. Neutrophils are innate immune cells required for the clearance of pathogenic organisms, including L. monocytogenes The diverse roles of neutrophils during both infectious and noninfectious inflammation have recently gained much attention. However, the impact of reactive oxygen species, and the enzymes that control their production, on neutrophil recruitment and function is not well understood. Using congenic mice with varying levels of extracellular superoxide dismutase (ecSOD) activity, we have recently shown that the presence of ecSOD decreases clearance of L. monocytogenes while increasing the recruitment of neutrophils that are not protective in the liver. The data presented here show that ecSOD activity does not lead to a cell-intrinsic increase in neutrophil-homing potential or a decrease in protection against L. monocytogenes Instead, ecSOD activity enhances the production of neutrophil-attracting factors and protects hyaluronic acid (HA) from damage. Furthermore, neutrophils from the livers of ecSOD-expressing mice have decreased intracellular and surface-bound myeloperoxidase, are less capable of killing phagocytosed L. monocytogenes, and have decreased oxidative burst. Collectively, our data reveal that ecSOD activity modulates neutrophil recruitment and function in a cell-extrinsic fashion, highlighting the importance of the enzyme in protecting tissues from oxidative damage.

Flavonoid-enriched fraction from Echinodorus macrophyllus aqueous extract exhibits high in-vitro and in-vivo anti-inflammatory activity

Objectives

Echinodorus macrophyllus (Kunth) Micheli (Alismataceae) is popularly used as an infusion to treat inflammatory diseases. This work fractionated the aqueous extract of E. macrophyllus (AEEm) to improve its anti-inflammatory effects.

Methods

Aqueous extract of E. macrophyllus was fractionated by Sephadex LH-20 and analysed by HPLC-DAD. Anti-inflammatory action was evaluated, in vivo, by air pouch model (total leucocyte, protein and leukotriene B4 (LTB4)), and, in vitro, by neutrophil migration (transwell assay) and its Mac1 expression (flow cytometry), and RAW 264.7 nitric oxide (NO) production (Griess reaction).

Key findings

Fr20 reduced total leucocyte at 2.5 mg/kg (29.7%) while ethanolic extract of E. macrophyllus (EAEm) increased it (94.0%). Fr20 showed higher (P < 0.05) inhibition (89.8%) of LTB4 in exudate than EAEm (75.0%). Fr20 and EAEm decreased exudate protein and inflammatory infiltrate in pouch tissues, in-vitro neutrophil migration, and NO production. Otherwise, Fr40 did not reduce leucocytes and exudate protein (until 50 mg/kg) nor tissue inflammation, and increased in-vitro NO production. The inhibition of neutrophil migration by EAEm, but not Fr20, was dependent on reduced Mac-1 expression.

Conclusions

The fractionation of AEEm provided a more potent anti-inflammatory fraction containing flavonoids (Fr20) that reduces the migration of neutrophils and LTB4 release, probably contributing to its mechanism of action.

Innate immune and growth promoting responses to caper (Capparis spinosa) extract in rainbow trout (Oncorhynchus mykiss)

Cytokine responses, non-specific immune activity and growth promotion effect of dietary caper (Capparis spinosa) supplementation were examined in rainbow trout (Oncorhynchus mykiss). Rainbow trout (12.04 ± 0.71 g) were fed diets containing three doses of caper methanolic extract [0 (Control), 0.1 and 0.5 g kg(-1) of feed] for 30 days. At the end of the feeding trial, expression levels of cytokine genes that included IL-1β, IL-8, TGF-β, IL-12p40, TNF-α1 and IL-10 in head kidney was analyzed using qRT-PCR, and blood and serum were collected to determine superoxide anion production (SAP), phagocytic, lysozyme and myeloperoxidase activities. Expression levels of all cytokines, except TNF-α1 were elevated in the 0.1 g kg(-1) caper extract fed fish group compared to other groups. In 0.5 g kg(-1) caper extract treated fish, only IL-12p40 and IL-10 genes were up-regulated compared to control group fish. SAP was increased in both caper extract treated groups compared to the control, and the highest level was observed in the 0.1 g kg(-1) group. Phagocytic activity in both the caper extract treated groups was increased compared to control with no differences observed between those groups. Lysozyme and myeloperoxidase activities were recorded to be the highest in the 0.1 g kg(-1) fed fish group compared to other groups. Growth promotion was affected positively when caper doses were increased. Survival rate was significantly higher in 0.1 and 0.5 g kg(-1) caper extract treated fish groups compared to control (P < 0.05) after challenged with Aeromonas hydrophila. These results indicate that caper extract stimulates innate immunity through cytokine-mediated responses and promote growth in rainbow trout.

Myeloperoxidase Stimulates Neutrophil Degranulation

Myeloperoxidase, heme enzyme of azurophilic granules in neutrophils, is released into the extracellular space in the inflammation foci. In neutrophils, it stimulates a dose-dependent release of lactoferrin (a protein of specific granules), lysozyme (a protein of specific and azurophilic granules), and elastase (a protein of azurophilic granules). 4-Aminobenzoic acid hydrazide, a potent inhibitor of peroxidase activity of myeloperoxidase, produced no effect on neutrophil degranulation. Using signal transduction inhibitors (genistein, methoxyverapamil, wortmannin, and NiCl2), we demonstrated that myeloperoxidase-induced degranulation of neutrophils resulted from enzyme interaction with the plasma membrane and depends on activation of tyrosine kinases, phosphatidylinositol 3-kinases (PI3K), and calcium signaling. Myeloperoxidase modified by oxidative/halogenation stress (chlorinated and monomeric forms of the enzyme) lost the potency to activate neutrophil degranulation.

Lung epithelium and myeloid cells cooperate to clear acute pneumococcal infection

The Gram-positive bacterium Streptococcus pneumoniae causes life-threatening infections, especially among immunocompromised patients. The host's immune system senses S. pneumoniae via different families of pattern recognition receptors, in particular the Toll-like receptor (TLR) family that promotes immune cell activation. Yet, while single TLRs are dispensable for initiating inflammatory responses against S. pneumoniae, the central TLR adapter protein myeloid differentiation factor 88 (MyD88) is of vital importance, as MyD88-deficient mice succumb rapidly to infection. Since MyD88 is ubiquitously expressed in hematopoietic and non-hematopoietic cells, the extent to which MyD88 signaling is required in different cell types to control S. pneumoniae is unknown. Therefore, we used novel conditional knockin mice to investigate the necessity of MyD88 signaling in distinct lung-resident myeloid and epithelial cells for the initiation of a protective immune response against S. pneumoniae. Here, we show that MyD88 signaling in lysozyme M (LysM)- and CD11c-expressing myeloid cells, as well as in pulmonary epithelial cells, is critical to restore inflammatory cytokine and antimicrobial peptide production, leading to efficient neutrophil recruitment and enhanced bacterial clearance. Overall, we show a novel synergistic requirement of compartment-specific MyD88 signaling in S. pneumoniae immunity.

Neutrophil Extracellular Traps Promote Angiogenesis: Evidence From Vascular Pathology in Pulmonary Hypertension

OBJECTIVE

Inflammation and dysregulated angiogenesis are features of endothelial dysfunction in pulmonary hypertension. Neutrophil extracellular traps (NETs), produced by dying neutrophils, contribute to pathogenesis of numerous vascular disorders but their role in pulmonary hypertension has not been studied. We sought evidence of (NETs) formation in pulmonary hypertension and investigated the effect of NETs on endothelial function.

APPROACH AND RESULTS

Plasma and lung tissues of patients with pulmonary hypertension were analyzed for NET markers. The effects of NETs on endothelial function were studied in vitro and in vivo. Patients with chronic thromboembolic pulmonary hypertension and idiopathic pulmonary hypertension showed elevated plasma levels of DNA, neutrophil elastase, and myeloperoxidase. NET-forming neutrophils and extensive areas of NETosis were found in the occlusive plexiform lesions and vascularized intrapulmonary thrombi. NETs induced nuclear factor κB-dependent endothelial angiogenesis in vitro and increased vascularization of matrigel plugs in vivo. Angiogenic responses were associated with increased release of matrix metalloproteinase-9, heparin-binding epidermal growth factor-like growth factor, latency-associated peptide of the transforming growth factor β1, and urokinase-type plasminogen activator, accompanied by increased endothelial permeability and cell motility. NETs-induced responses depended on myeloperoxidase/H2O2-dependent activation of Toll-like receptor 4/nuclear factor κB signaling. NETs stimulated the release of endothelin-1 in HPAECs (human pulmonary artery endothelial cells) and stimulated pulmonary smooth muscle cell proliferation in vitro.

CONCLUSIONS

We are the first to implicate NETs in angiogenesis and provide a functional link between NETs and inflammatory angiogenesis in vitro and in vivo. We demonstrate the potential pathological relevance of this in 2 diseases of disordered vascular homeostasis, pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension.

Nutritional Evaluation of an EPA-DHA Oil from Transgenic Camelina sativa in Feeds for Post-Smolt Atlantic Salmon (Salmo salar L.)

Vegetable oils (VO) are possible substitutes for fish oil in aquafeeds but their use is limited by their lack of omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA). However, oilseed crops can be modified to produce n-3 LC-PUFA such as eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, representing a potential option to fill the gap between supply and demand of these important nutrients. Camelina sativa was metabolically engineered to produce a seed oil with around 15% total n-3 LC-PUFA to potentially substitute for fish oil in salmon feeds. Post-smolt Atlantic salmon (Salmo salar) were fed for 11-weeks with one of three experimental diets containing either fish oil (FO), wild-type Camelina oil (WCO) or transgenic Camelina oil (DCO) as added lipid source to evaluate fish performance, nutrient digestibility, tissue n-3 LC-PUFA, and metabolic impact determined by liver transcriptome analysis. The DCO diet did not affect any of the performance or health parameters studied and enhanced apparent digestibility of EPA and DHA compared to the WCO diet. The level of total n-3 LC-PUFA was higher in all the tissues of DCO-fed fish than in WCO-fed fish with levels in liver similar to those in fish fed FO. Endogenous LC-PUFA biosynthetic activity was observed in fish fed both the Camelina oil diets as indicated by the liver transcriptome and levels of intermediate metabolites such as docosapentaenoic acid, with data suggesting that the dietary combination of EPA and DHA inhibited desaturation and elongation activities. Expression of genes involved in phospholipid and triacylglycerol metabolism followed a similar pattern in fish fed DCO and WCO despite the difference in n-3 LC-PUFA contents.

Treatment with geraniol ameliorates methionine-choline-deficient diet-induced non-alcoholic steatohepatitis in rats

BACKGROUND AND AIM

Non-alcoholic steatohepatitis (NASH) is one of the most common causes of chronic liver disease and is considered to be a causative factor of cryptogenic cirrhosis and hepatocellular carcinoma. The aim of this work was to investigate whether treatment with geraniol (a monoterpene) attenuated NASH induced by methionine-choline-deficient (MCD) diet in rats.

METHODS

Rats were fed with MCD diet to induce NASH and treated with geraniol (200 mg/kg/day) for 10 weeks.

RESULTS

Treatment with geraniol reduced histological scores, fibrosis, and apoptosis in livers, lowered activities of alanine aminotransferase and aspartate aminotransferase in serum, and attenuated hepatic fat accumulation in rats fed with MCD diet. Treatment with geraniol preserved hepatic mitochondrial function, evidenced by reduced mitochondrial reactive oxygen species formation, enhanced adenosine triphosphate formation and membrane integrity, restored mitochondrial electron transport chain enzyme activity, and increased mitochondrial DNA content in rats fed with MCD diet. Treatment with geraniol reduced uncoupling protein 2 protein expression, and enhanced protein expression of prohibitin, mRNA expression of peroxisome proliferator-activated receptor α, and activity of mitochondrial carnitine palmitoyl transferase-I in livers of rats fed with MCD diet. Treatment with geraniol abated oxidative stress, evidenced by reduced malondialdehyde and 3-nitrotyrosine formation, enhanced activity of glutathione S-epoxide transferase, and down-regulated expression of inducible nitric oxide synthase and cytochrome P450 2E1 in livers of rats fed with MCD diet. Treatment with geraniol reduced myeloperoxidase activity and protein expression of tumor necrosis factor alpha and IL-6 in livers of rats fed with MCD diet.

CONCLUSION

Treatment with geraniol attenuated MCD-induced NASH in rats.

Myeloperoxidase: Bridging the gap in neurodegeneration

Neurodegenerative conditions present a group of complex disease pathologies mostly due to unknown aetiology resulting in neuronal death and permanent neurological disability. Any undesirable stress to the brain, disrupts homeostatic balance, through a remarkable convergence of pathophysiological changes and immune dysregulation. The crosstalk between inflammatory and oxidative mechanisms results in the release of neurotoxic mediators apparently spearheaded by myeloperoxidase derived from activated microglia, astrocytes, neurons as well as peripheral inflammatory cells. These isolated entities combinedly have the potential to flare up and contribute significantly to neuropathology and disease progression. Recent, clinicopathological evidence support the association of myeloperoxidase and its cytotoxic product, hypochlorous acid in a plethora of neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Amyotrophic lateral sclerosis, Multiple sclerosis, Stroke, Epilepsy etc. But the biochemical and mechanistic insights into myeloperoxidase mediated neuroinflammation and neuronal death is still an uncharted territory. The current review outlines the emerging recognition of myeloperoxidase in neurodegeneration, which may offer novel therapeutic and diagnostic targets for neurodegenerative disorders.

Qingchang Wenzhong Decoction Ameliorates Dextran Sulphate Sodium-Induced Ulcerative Colitis in Rats by Downregulating the IP10/CXCR3 Axis-Mediated Inflammatory Response

Qingchang Wenzhong Decoction (QCWZD) is an effective traditional Chinese medicine prescription. Our previous studies have shown that QCWZD has significant efficacy in patients with mild-to-moderate ulcerative colitis (UC) and in colonic mucosa repair in UC rat models. However, the exact underlying mechanism remains unknown. Thus, this study was conducted to determine QCWZD's efficacy and mechanism in dextran sulphate sodium- (DSS-) induced UC rat models, which were established by 7-day administration of 4.5% DSS solution. QCWZD was administered daily for 7 days, after which the rats were euthanized. Disease activity index (DAI), histological score (HS), and myeloperoxidase (MPO) level were determined to evaluate UC severity. Serum interferon gamma-induced protein 10 (IP10) levels were determined using ELISA kits. Western blotting and real-time polymerase chain reaction were, respectively, used to determine colonic protein and gene expression of IP10, chemokine (cys-x-cys motif) receptor (CXCR)3, and nuclear factor- (NF-) κB p65. Intragastric QCWZD administration ameliorated DSS-induced UC, as evidenced by decreased DAI, HS, and MPO levels. Furthermore, QCWZD decreased the protein and gene expression of IP10, CXCR3, and NF-κB p65. Overall, these results suggest that QCWZD ameliorates DSS-induced UC in rats by downregulating the IP10/CXCR3 axis-mediated inflammatory response and may be a novel UC therapy.

Insecticide chlorpyrifos and fungicide carbendazim, common food contaminants mixture, induce hepatic, renal, and splenic oxidative damage in female rats

The fungicide carbendazim (CBZ) and insecticide chlorpyrifos (CPF) are currently applied together by farmers for the control of pests. Here, we investigated the impacts of 7 days oral co-exposure to 10 mg/kg body weight of CPF and 50 mg/kg body weight of CBZ on selected oxidative stress and antioxidant biomarkers in the liver, kidney, and spleen of female rats. The results showed that while the body weight gain and relative organ weights were not significantly affected after separate exposure to CPF and CBZ, there was a significant decrease in the body weight gain with concomitant increases in the relative kidney and spleen weights of rats treated with the mixture. Also, CPF and CBZ co-exposure significantly increased the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea, and creatinine ( p < 0.05) when compared with the groups treated with CBZ or CPF alone and the control. The significant decreases in both antioxidant enzymes activities and nonenzymatic antioxidant level following individual administration of CPF and CBZ to rats were intensified in the co-exposure group ( p < 0.05). Additionally, the marked increases in the levels of oxidative stress indices in liver, kidney, and spleen of rats treated with CPF or CBZ alone were intensified in the co-exposure group ( p < 0.05). Histopathologically, co-exposure to CPF and CBZ exacerbates their individual effects on the liver, kidney, and spleen. These findings showed that co-exposure to CPF and CBZ in rats elicited more severe oxidative damage on the liver, kidney, and spleen of the rats, indicative of an additive effect compared to CPF or CBZ alone and as such, may pose a greater environmental risk to humans.

Feedback Amplification of Neutrophil Function

As the first line of innate immune defense, neutrophils need to mount a rapid and robust antimicrobial response. Recent studies implicate various positive feedback amplification processes in achieving that goal. Feedback amplification ensures effective migration of neutrophils in shallow chemotactic gradients, multiple waves of neutrophil recruitment to the site of inflammation, and the augmentation of various effector functions of the cells. We review here such positive feedback loops including intracellular and autocrine processes, paracrine effects mediated by lipid (LTB4), chemokine, and cytokine mediators, and bidirectional interactions with the complement system and with other immune and non-immune cells. These amplification mechanisms are not only involved in antimicrobial immunity but also contribute to neutrophil-mediated tissue damage under pathological conditions.

Role of Myeloperoxidase in Patients with Chronic Kidney Disease

Chronic kidney disease (CKD) is a worldwide public health problem. Patients with CKD have a number of disorders in the organism, and the presence of oxidative stress and systemic inflammation in these patients is the subject of numerous studies. Chronic inflammation joined with oxidative stress contributes to the development of numerous complications: accelerated atherosclerosis process and cardiovascular disease, emergence of Type 2 diabetes mellitus, development of malnutrition, anaemia, hyperparathyroidism, and so forth, affecting the prognosis and quality of life of patients with CKD. In this review we presented the potential role of the myeloperoxidase enzyme in the production of reactive/chlorinating intermediates and their role in oxidative damage to biomolecules in the body of patients with chronic kidney disease and end-stage renal disease. In addition, we discussed the role of modified lipoprotein particles under the influence of prooxidant MPO intermediates in the development of endothelial changes and cardiovascular complications in renal failure.

The Impact of Myeloperoxidase and Activated Macrophages on Metaphase II Mouse Oocyte Quality

Myeloperoxidase (MPO), an abundant heme-containing enzyme present in neutrophils, monocytes, and macrophages, is produced in high levels during inflammation, and associated with poor reproductive outcomes. MPO is known to generate hypochlorous acid (HOCl), a damaging reactive oxygen species (ROS) utilizing hydrogen peroxide (H₂O₂) and chloride (Cl^-). Here we investigate the effect of activated immune cells and MPO on oocyte quality. Mouse metaphase II oocytes were divided into the following groups: 1) Incubation with a catalytic amount of MPO (40 nM) for different incubation periods in the presence of 100 mM Cl^- with and without H₂O₂ and with and without melatonin (100 μM), at 37°C (n = 648/648 total number of oocytes in each group for oocytes with and without cumulus cells); 2) Co-cultured with activated mouse peritoneal macrophage and neutrophils cells (1.0 x 10⁶ cells/ml) in the absence and presence of melatonin (200 μM), an MPO inhibitor/ROS scavenger, for different incubation periods in HTF media, at 37°C (n = 200/200); 3) Untreated oocytes incubated for 4 hrs as controls (n = 73/64). Oocytes were then fixed, stained and scored based on the microtubule morphology and chromosomal alignment. All treatments were found to negatively affect oocyte quality in a time dependent fashion as compared to controls. In all cases the presence of cumulus cells offered no protection; however significant protection was offered by melatonin. Similar results were obtained with oocytes treated with neutrophils. This work provides a direct link between MPO and decreased oocyte quality. Therefore, strategies to decrease MPO mediated inflammation may influence reproductive outcomes.

Neutrophil-Mediated Regulation of Innate and Adaptive Immunity: The Role of Myeloperoxidase

Neutrophils are no longer seen as leukocytes with a sole function of being the essential first responders in the removal of pathogens at sites of infection. Being armed with numerous pro- and anti-inflammatory mediators, these phagocytes can also contribute to the development of various autoimmune diseases and can positively or negatively regulate the generation of adaptive immune responses. In this review, we will discuss how myeloperoxidase, the most abundant neutrophil granule protein, plays a key role in the various functions of neutrophils in innate and adaptive immunity.

Binding of human myeloperoxidase to red blood cells: Molecular targets and biophysical consequences at the plasma membrane level

Myeloperoxidase (MPO) is an oxidant-producing enzyme that can also bind to cellular surface proteins. We found that band 3 protein and glycophorins A and B were the key MPO-binding targets of human red blood cells (RBCs). The interaction of MPO with RBC proteins was mostly electrostatic in nature because it was inhibited by desialation, exogenic sialic acid, high ionic strength, and extreme pH. In addition, MPO failed to interfere with the lectin-induced agglutination of RBCs, suggesting a minor role of glycan-recognizing mechanisms in MPO binding. Multiple biophysical properties of RBCs were altered in the presence of native (i.e., not hypochlorous acid-damaged) MPO. These changes included transmembrane potential, availability of intracellular Ca(2+), and lipid organization in the plasma membrane. MPO-treated erythrocytes became larger in size, structurally more rigid, and hypersensitive to acidic and osmotic hemolysis. Furthermore, we found a significant correlation between the plasma MPO concentration and RBC rigidity index in type-2 diabetes patients with coronary heart disease. These findings suggest that MPO functions as a mediator of novel regulatory mechanism in microcirculation, indicating the influence of MPO-induced abnormalities on RBC deformability under pathological stress conditions.

Inhibition of myeloperoxidase at the peak of experimental autoimmune encephalomyelitis restores blood-brain barrier integrity and ameliorates disease severity

Oxidative stress is thought to contribute to disease pathogenesis in the central nervous system (CNS) disease multiple sclerosis (MS). Myeloperoxidase (MPO), a potent peroxidase that generates toxic radicals and oxidants, is increased in the CNS during MS. However, the exact mechanism whereby MPO drives MS pathology is not known. We addressed this question by inhibiting MPO in mice with experimental autoimmune encephalomyelitis (EAE) using our non-toxic MPO inhibitor N-acetyl lysyltyrosylcysteine amide (KYC). We found that therapeutic administration of KYC for 5 days starting at the peak of disease significantly attenuated EAE disease severity, reduced myeloid cell numbers and permeability of the blood-brain barrier. These data indicate that inhibition of MPO by KYC restores blood-brain barrier integrity thereby limiting migration of myeloid cells into the CNS that drive EAE pathogenesis. In addition, these observations indicate that KYC may be an effective therapeutic agent for the treatment of MS. We propose that during experimental autoimmune encephalomyelitis (EAE) onset macrophages and neutrophils migrate into the CNS and upon activation release myeloperoxidase (MPO) that promotes disruption of the blood-brain barrier (BBB) and disease progression. KYC restores BBB function by inhibiting MPO activity and in so doing ameliorates disease progression.

Reactive Oxygen-Related Diseases: Therapeutic Targets and Emerging Clinical Indications

SIGNIFICANCE

Enhanced levels of reactive oxygen species (ROS) have been associated with different disease states. Most attempts to validate and exploit these associations by chronic antioxidant therapies have provided disappointing results. Hence, the clinical relevance of ROS is still largely unclear.

RECENT ADVANCES

We are now beginning to understand the reasons for these failures, which reside in the many important physiological roles of ROS in cell signaling. To exploit ROS therapeutically, it would be essential to define and treat the disease-relevant ROS at the right moment and leave physiological ROS formation intact. This breakthrough seems now within reach.

CRITICAL ISSUES

Rather than antioxidants, a new generation of protein targets for classical pharmacological agents includes ROS-forming or toxifying enzymes or proteins that are oxidatively damaged and can be functionally repaired.

FUTURE DIRECTIONS

Linking these target proteins in future to specific disease states and providing in each case proof of principle will be essential for translating the oxidative stress concept into the clinic.

Decreased progranulin levels in patients and rats with subarachnoid hemorrhage: a potential role in inhibiting inflammation by suppressing neutrophil recruitment

Background

Subarachnoid hemorrhage (SAH) is a devastating neurological injury with high morbidity and mortality that is mainly caused by early brain injury (EBI). Progranulin (PGRN) is known to be involved in various biological functions, such as anti-inflammation and tissue repair. This study aimed to investigate the change of PGRN in the brain after SAH and its role on EBI.

Methods

The levels of PGRN, myeloperoxidase (MPO), interleukin1β (IL-1β), and tumor necrosis factor-α (TNF-α) were detected in the cerebrospinal fluid (CSF) from SAH patients by enzyme-linked immunosorbent assay (ELISA). In addition, PGRN levels were also detected in the cerebral cortex after experimental SAH in rats by western blotting and immunohistochemistry (IHC). Recombinant human PGRN (r-PGRN) or an equal volume of phosphate-buffered saline (PBS) was administrated at 30 min after SAH. All rats were subsequently sacrificed at 24 h after SAH. Neurological score and brain water content were assessed. For mechanistic studies, the changes of MPO, matrix metalloproteinase-9 (MMP-9), zonula occludens 1 (ZO-1), Bcl-2, and cleaved caspase-3 were examined by western blotting and the levels of pro-inflammatory cytokines (IL-1β and TNF-α) were determined by ELISA. In addition, neuronal apoptosis and blood brain barrier (BBB) permeability were examined.

Results

The levels of PGRN significantly decreased, and the levels of MPO, IL-1β, and TNF-α were markedly elevated in the CSF from SAH patients. In rats, PGRN levels in the brain also decreased after SAH. Administration of r-PGRN decreased brain water content and improved neurological scores at 24 h after SAH. These changes were associated with marked reductions in MPO, MMP-9, and proinflammation cytokine levels, as well as increased levels of Bcl-2 and ZO-1. In addition, neuronal apoptosis and BBB permeability were alleviated by r-PGRN.

Conclusions

These results indicate that the levels of PGRN decreased after SAH and that r-PGRN alleviates EBI after SAH possibly via inhibition of neutrophil recruitment, providing a new target for the treatment of SAH.

Association of microparticles and neutrophil activation with decompression sickness

Decompression sickness (DCS) is a systemic disorder, assumed due to gas bubbles, but additional factors are likely to play a role. Circulating microparticles (MPs)—vesicular structures with diameters of 0.1-1.0 μm—have been implicated, but data in human divers have been lacking. We hypothesized that the number of blood-borne, Annexin V-positive MPs and neutrophil activation, assessed as surface MPO staining, would differ between self-contained underwater breathing-apparatus divers suffering from DCS vs. asymptomatic divers. Blood was analyzed from 280 divers who had been exposed to maximum depths from 7 to 105 meters; 185 were control/asymptomatic divers, and 90 were diagnosed with DCS. Elevations of MPs and neutrophil activation occurred in all divers but normalized within 24 h in those who were asymptomatic. MPs, bearing the following proteins: CD66b, CD41, CD31, CD142, CD235, and von Willebrand factor, were between 2.4- and 11.7-fold higher in blood from divers with DCS vs. asymptomatic divers, matched for time of sample acquisition, maximum diving depth, and breathing gas. Multiple logistic regression analysis documented significant associations ( P < 0.001) between DCS and MPs and for neutrophil MPO staining. Effect estimates were not altered by gender, body mass index, use of nonsteroidal anti-inflammatory agents, or emergency oxygen treatment and were modestly influenced by divers' age, choice of breathing gas during diving, maximum diving depth, and whether repetitive diving had been performed. There were no significant associations between DCS and number of MPs without surface proteins listed above. We conclude that MP production and neutrophil activation exhibit strong associations with DCS.

Blockade of exosome generation with GW4869 dampens the sepsis-induced inflammation and cardiac dysfunction

Sepsis is an infection-induced severe inflammatory disorder that leads to multiple organ failure. Amongst organs affected, myocardial depression is believed to be a major contributor to septic death. While it has been identified that large amounts of circulating pro-inflammatory cytokines are culprit for triggering cardiac dysfunction in sepsis, the underlying mechanisms remain obscure. Additionally, recent studies have shown that exosomes released from bacteria-infected macrophages are pro-inflammatory. Hence, we examined in this study whether blocking the generation of exosomes would be protective against sepsis-induced inflammatory response and cardiac dysfunction. To this end, we pre-treated RAW264.7 macrophages with GW4869, an inhibitor of exosome biogenesis/release, followed by endotoxin (LPS) challenge. In vivo, we injected wild-type (WT) mice with GW4869 for 1h prior to endotoxin treatment or cecal ligation/puncture (CLP) surgery. We observed that pre-treatment with GW4869 significantly impaired release of both exosomes and pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) in RAW264.7 macrophages. At 12h after LPS treatment or CLP surgery, WT mice pre-treated with GW4869 displayed lower amounts of exosomes and pro-inflammatory cytokines in the serum than control PBS-injected mice. Accordingly, GW4869 treatment diminished the sepsis-induced cardiac inflammation, attenuated myocardial depression and prolonged survival. Together, our findings indicate that blockade of exosome generation in sepsis dampens the sepsis-triggered inflammatory response and thereby, improves cardiac function and survival.

L-4F inhibits lipopolysaccharide-mediated activation of primary human neutrophils

Human apolipoprotein A-I (apoA-I) mimetic L-4F inhibits acute inflammation in endotoxemic animals. Since neutrophils play a crucial role in septic inflammation, we examined the effects of L-4F, compared to apoA-I, on lipopolysaccharide (LPS)-mediated activation of human neutrophils. We performed bioassays in human blood, isolated human neutrophils (incubated in 50 % donor plasma), and isolated human leukocytes (incubated in 5 and 50 % plasma) in vitro. In whole blood, both L-4F and apoA-I inhibited LPS-mediated elevation of TNF-α and IL-6. In LPS-stimulated neutrophils, L-4F and apoA-I (40 μg/ml) also decreased myeloperoxidase and TNF-α levels; however, L-4F tended to be superior in inhibiting LPS-mediated increase in IL-6 levels, membrane lipid rafts abundance and CD11b expression. In parallel experiments, when TNF-α and IL-8, instead of LPS, was used for cell stimulation, L-4F and/or apoA-I revealed only limited efficacy. In LPS-stimulated leukocytes, L-4F was as effective as apoA-I in reducing superoxide formation in 50 % donor plasma, and more effective in 5 % donor plasma (P<0.05). Limulus ambocyte lysate (LAL) and surface plasmon resonance assays showed that L-4F neutralizes LAL endotoxin activity more effectively than apoA-I (P<0.05) likely due to avid binding to LPS. We conclude that (1) direct binding/neutralization of LPS is a major mechanism of L-4F in vitro; (2) while L-4F has similar efficacy to apoA-I in anti-endotoxin effects in whole blood, it demonstrates superior efficacy to apoA-I in aqueous solutions and fluids with limited plasma components. This study rationalizes the utility of L-4F in the treatment of inflammation that is mediated by endotoxin-activated neutrophils.

Effect of pioglitazone on excitotoxic neuronal damage in the mouse hippocampus

Pioglitazone (PGZ), a synthetic peroxisome proliferator-activated receptor γ agonist, is known to regulate inflammatory process and to have neuroprotective effects against neurological disorders. In the present study, we examined the effects of 30 mg/kg PGZ on excitotoxic neuronal damage and glial activation in the mouse hippocampus following intracerebroventricular injection of kainic acid (KA). PGZ treatment significantly reduced seizure-like behavior. PGZ had the neuroprotective effect against KA-induced neuronal damage and attenuated the activations of astrocytes and microglia in the hippocampal CA3 region. In addition, MPO and NFκB immunoreactivities in the glial cells were also decreased in the PGZ-treated group. These results indicate that PGZ had anticonvulsant and neuroprotective effects against KA-induced excitotocix injury, and that neuroprotective effect of PGZ might be due to the attenuation of KA-induced activation in astrocytes and microglia as well as KA-induced increases in MPO and NFκB.

Role of Hypoxia Inducible Factor-1α (HIF-1α) in Innate Defense against Uropathogenic Escherichia coli Infection

Uropathogenic E. coli (UPEC) is the primary cause of urinary tract infections (UTI) affecting approximately 150 million people worldwide. Here, we revealed the importance of transcriptional regulator hypoxia-inducible factor-1 α subunit (HIF-1α) in innate defense against UPEC-mediated UTI. The effects of AKB-4924, a HIF-1α stabilizing agent, were studied using human uroepithelial cells (5637) and a murine UTI model. UPEC adherence and invasion were significantly reduced in 5637 cells when HIF-1α protein was allowed to accumulate. Uroepithelial cells treated with AKB-4924 also experienced reduced cell death and exfoliation upon UPEC challenge. In vivo, fewer UPEC were recovered from the urine, bladders and kidneys of mice treated transurethrally with AKB-4924, whereas increased bacteria were recovered from bladders of mice with a HIF-1α deletion. Bladders and kidneys of AKB-4924 treated mice developed less inflammation as evidenced by decreased pro-inflammatory cytokine release and neutrophil activity. AKB-4924 impairs infection in uroepithelial cells and bladders, and could be correlated with enhanced production of nitric oxide and antimicrobial peptides cathelicidin and β-defensin-2. We conclude that HIF-1α transcriptional regulation plays a key role in defense of the urinary tract against UPEC infection, and that pharmacological HIF-1α boosting could be explored further as an adjunctive therapy strategy for serious or recurrent UTI.

Urinary tract infection (UTI), commonly caused by uropathogenic E.coli (UPEC), affects more than 150 million people worldwide, resulting in 14 million hospital visits per year and an estimated total cost of 6 billion dollars in direct health care. Due to the high prevalence of UTI and rapid emergence of antibiotic-resistant bacteria, new effective strategies to prevent and treat UTI are urgently needed. Here, we describe a global regulatory role of transcription factor hypoxia-inducible factor-1 (HIF-1) in innate antimicrobial defense against UPEC. HIF-1 stabilization reduces UPEC attachment to and invasion of uroepithelial cells, and protects bladders from UPEC-mediated cytotoxicity in vivo. In the murine UTI model, we found normal bladder HIF-1 expression is required for efficient UPEC clearance, since HIF-1-deficient mice suffer more severe infection than normal mice. Further studies showed that key elements of host protection provided by HIF-1 regulation are uroepithelial cell nitric oxide and antimicrobial peptide production. This study provides valuable insight into the importance of HIF-1 in supporting host immunity during UTI and its potential as a therapeutic target.

Ligand recognition specificity of leukocyte integrin αMβ2 (Mac-1, CD11b/CD18) and its functional consequences

The broad recognition specificity exhibited by integrin α(M)β2 (Mac-1, CD11b/CD18) has allowed this adhesion receptor to play innumerable roles in leukocyte biology, yet we know little about how and why α(M)β2 binds its multiple ligands. Within α(M)β2, the α(M)I-domain is responsible for integrin's multiligand binding properties. To identify its recognition motif, we screened peptide libraries spanning sequences of many known protein ligands for α(M)I-domain binding and also selected the α(M)I-domain recognition sequences by phage display. Analyses of >1400 binding and nonbinding peptides derived from peptide libraries showed that a key feature of the α(M)I-domain recognition motif is a small core consisting of basic amino acids flanked by hydrophobic residues. Furthermore, the peptides selected by phage display conformed to a similar pattern. Identification of the recognition motif allowed the construction of an algorithm that reliably predicts the α(M)I-domain binding sites in the α(M)β2 ligands. The recognition specificity of the α(M)I-domain resembles that of some chaperones, which allows it to bind segments exposed in unfolded proteins. The disclosure of the α(M)β2 binding preferences allowed the prediction that cationic host defense peptides, which are strikingly enriched in the α(M)I-domain recognition motifs, represent a new class of α(M)β2 ligands. This prediction has been tested by examining the interaction of α(M)β2 with the human cathelicidin peptide LL-37. LL-37 induced a potent α(M)β2-dependent cell migratory response and caused activation of α(M)β2 on neutrophils. The newly revealed recognition specificity of α(M)β2 toward unfolded protein segments and cationic proteins and peptides suggests that α(M)β2 may serve as a previously proposed "alarmin" receptor with important roles in innate host defense.

[Adverse effects of nanomaterials on biological defense mechanisms]

Nanomaterials are defined as substances that have at least one dimension <100 nm. They have unique physicochemical properties and innovative functions compared with conventional materials of submicron size. As such, they have many applications in nanomedicine, such as in drug delivery or diagnostic and imaging systems. However, there are a number of safety concerns regarding the use of nanomaterials. Therefore it is essential not only to obtain more information about nanomaterials to ensure their safety, but also to identify novel biomarkers that may predict adverse biological effects induced by nanomaterials. In this regard, neutrophil activation is thought to be involved in some biological responses that are induced after exposure to nanomaterials. However, the detailed mechanisms involved in these events are poorly understood. Here, we examine neutrophil activation induced by nanomaterials. In addition, to develop a safe and effective form of a nanomaterial, we attempted to develop potential biomarkers of silica nanoparticles by proteomics analysis. We believe that our data could provide information of value in nanomaterial risk management and in the establishment of guidelines for assessment of their use.

Characterization of myeloid-specific peroxidase, keratin 8, and dual specificity phosphatase 1 as innate immune genes involved in the resistance of crucian carp (Carassius auratus gibelio) to Cyprinid herpesvirus 2 infection

Myeloid-specific peroxidase (MPO), keratin 8 (KRT-8), and dual specificity phosphatase 1 (DUSP-1) are believed to play essential roles in innate immunity. Through suppression subtractive hybridization (SSH) analysis, we previously identified MPO, KRT-8, and DUSP-1 as the three genes that were the most significantly upregulated in crucian carp (Carassius auratus gibelio) that survived Cyprinid herpesvirus 2 (CyHV-2) infection. Here, we have further characterized these three genes and their response to pathogen challenge. The open reading frames (ORF) of MPO, KRT-8, and DUSP-1 were cloned by RACE technique and sequenced. The full-length cDNAs of the three genes contained ORFs of 2289, 1575 and 1083 bp respectively. The polypeptides from each ORF were projected to contain 762 (MPO), 524 (KRT-8), and 360 (DUSP-1) amino acids. Phylogenetic analysis showed that the three genes were most closely related to zebrafish. We found that MPO, KRT-8, and DUSP-1 were expressed at low levels in all of the tissues examined in healthy crucian carp. Quantitative real-time RT-PCR analysis indicated that MPO, KRT-8, and DUSP-1 mRNA expression was significantly upregulated within 72 h of CyHV-2 infection compared to mock infected controls. Maximum expression of MPO was detected at 24 hpi (2.71-fold, P < 0.05). While, 12 hpi (3.80-fold, P < 0.01) and 6 hpi (8.70-fold, P < 0.01) were the highest expression time points for KRT-8 and DUSP-1, respectively. In contrast, after Aeromonas hydrophila challenge, the transcripts of these three genes remained unchanged or slightly down-regulated. For the fish survived from viral infection, expression levels of MPO and KRT-8 were 2.72 fold and 2.47 fold higher than those of fish died from acute infection, and similar level of DUSP-1 was observed in samples of survived fish. These data suggested MPO, KRT-8 and DUSP-1 might be involved in the antiviral, but not antibacterial innate immune response in crucian carp. These findings also support the use of MPO and KRT-8 as immunological markers for a response to viral infection in crucian carp.

Antinociceptive and anti-inflammatory activities of Bridelia retusa methanolic fruit extract in experimental animals

Antinociceptive and anti-inflammatory potentials of methanolic extract of Bridelia retusa fruit (BRME) were evaluated against different animal models in rodents. Antinociceptive effects of BRME were assessed in mice using the acetic acid-induced writhing and formalin test. Anti-inflammatory effects of BRME in three different doses, namely, 100, 200, and 400 mg/kg, were evaluated by utilizing different animal models representing various changes associated with inflammation, namely, carrageenan-induced paw oedema, histamine and serotonin-induced paw oedema, arachidonic acid-induced paw oedema, formalin-induced paw oedema, TPA-induced ear oedema, acetic acid-induced vascular permeability, total WBC count in paw fluid, and myeloperoxidase assay. Also BRME was phytochemically evaluated using chromatographic method. The BRME did not exhibit any signs of toxicity up to a dose of 2000 mg/kg. The extract showed statistical significant inhibition of induced nociception and inflammation in dose dependent manner. The higher dose of extract significantly inhibited pain and inflammation against control (P < 0.001). HPLC results revealed the presence of gallic acid and ellagic acid as phytoconstituents in BRME and it was proven as anti-inflammatory agents. The present study scientifically demonstrated the antinociceptive and anti-inflammatory potential of fruit of B. retusa methanolic extract. These effects may be attributed to the presence of polyphenolic phytoconstituents in the extract.

Immunomodulation with eicosapentaenoic acid supports the treatment of autoimmune small-vessel vasculitis

Small-vessel vasculitis is a life-threatening autoimmune disease that is frequently associated with anti-neutrophil cytoplasmic antibodies (ANCAs). Conventional immunotherapy including steroids and cyclophosphamide can cause serious adverse events, limiting the efficacy and safety of treatment. Eicosapentaenoic acid (EPA), a key component of fish oil, is an omega-3 polyunsaturated fatty acid widely known to be cardioprotective and beneficial for vascular function. We report two elderly patients with systemic ANCA-associated vasculitis (AAV) in whom the administration of EPA in concert with steroids safely induced and maintained remission, without the use of additioal immunosuppressants. To explore the mechanisms by which EPA enhances the treatment of AAV, we employed SCG/Kj mice as a spontaneous murine model of AAV. Dietary enrichment with EPA significantly delayed the onset of crescentic glomerulonephritis and prolonged the overall survival. EPA-derived anti-inflammatory lipid mediators and their precursors were present in the kidney, plasma, spleen, and lungs in the EPA-treated mice. Furthermore, a decrease in ANCA production and CD4/CD8-double negative T cells, and an increase in Foxp3(+) regulatory T cells in the lymph nodes of the kidney were observed in the EPA-treated mice. These clinical and experimental observations suggest that EPA can safely support and augment conventional therapy for treating autoimmune small-vessel vasculitis.

Xilei san ameliorates experimental colitis in rats by selectively degrading proinflammatory mediators and promoting mucosal repair

Xilei san (XLS), a herbal preparation widely used in China for erosive and ulcerative diseases, has been shown to be effective in ulcerative colitis (UC). The present experiments were conducted to assess its efficacy and determine its mechanism of action in a rat model that resembles human UC. The model was induced by adding 4% dextran sulfate sodium (DSS) to the rats' drinking water for 7 days. XLS was administered daily by retention enema from day 2 to day 7; the rats were sacrificed on day 8. The colon tissues were obtained for further experiments. A histological damage score and the activity of tissue myeloperoxidase were used to evaluate the severity of the colitis. The colonic cytokine levels were detected in a suspension array, and epithelial proliferation was assessed using Ki-67 immunohistochemistry. Intrarectal administration of XLS attenuated the DSS-induced colitis, as evidenced by a reduction in both the histological damage score and myeloperoxidase activity. It also decreased the levels of proinflammatory cytokines, but increased the mucosal repair-related cytokines. In addition, the epithelial Ki-67 expression was upregulated by XLS. These results suggest that XLS attenuates DSS-induced colitis by degrading proinflammatory mediators and promoting mucosal repair. XLS could be a potential topical treatment for human UC.

Effects of ghrelin on sepsis-induced acute kidney injury: one step forward

BACKGROUND

Among the several disorders induced by sepsis, acute kidney injury (AKI) represents the most important economic burden problem that is associated with high mortality and morbidity rates. The aim of this study was to investigate the anti-inflammatory effects of ghrelin in sepsis-induced AKI and the possible role of vagus nerve.

METHODS

Five groups were included: sham, cecal ligation and puncture (CLP), CLP-ghrelin, CLP-vagotomy and CLP-vagotomy-ghrelin group.

RESULTS

Ghrelin treatment immediately after induction of CLP, significantly improved renal Glomerular filtration rate (GFR), serum creatinine, BUN and renal necrosis score as compared to the unprotected CLP group. In addition, ghrelin significantly decreased renal TNF alpha (111.5 ± 10.35 vs. 291.8 ± 15.8 pg/mg ptn), VCAM1 (6.28 ± 1.7 vs. 12.9 ± 1.2 µ/g ptn) and MPO (0.95 ± 0.13 vs. 2.5 ± 0.4 µ/g ptn) without significant increase in renal IL-10. Those effects were abolished by vagotomy.

CONCLUSION

We concluded that ghrelin could represent new therapeutic window in early treatment of sepsis-induced AKI and this could be mainly due to its anti-inflammatory effects.

A neutrophil intrinsic impairment affecting Rab27a and degranulation in cystic fibrosis is corrected by CFTR potentiator therapy

Studies have endeavored to reconcile whether dysfunction of neutrophils in people with cystic fibrosis (CF) is a result of the genetic defect or is secondary due to infection and inflammation. In this study, we illustrate that disrupted function of the CF transmembrane conductance regulator (CFTR), such as that which occurs in patients with ∆F508 and/or G551D mutations, correlates with impaired degranulation of antimicrobial proteins. We demonstrate that CF blood neutrophils release less secondary and tertiary granule components compared with control cells and that activation of the low-molecular-mass GTP-binding protein Rab27a, involved in the regulation of granule trafficking, is defective. The mechanism leading to impaired degranulation involves altered ion homeostasis caused by defective CFTR function with increased cytosolic levels of chloride and sodium, yet decreased magnesium measured in CF neutrophils. Decreased magnesium concentration in vivo and in vitro resulted in significantly decreased levels of GTP-bound Rab27a. Treatment of G551D patients with the ion channel potentiator ivacaftor resulted in normalized neutrophil cytosolic ion levels and activation of Rab27a, thereby leading to increased degranulation and bacterial killing. Our results confirm that intrinsic alterations of circulating neutrophils from patients with CF are corrected by ivacaftor, thus illustrating additional clinical benefits for CFTR modulator therapy.