Tissue injury in neutrophilic inflammation

The dual functions of the GTPase BipA in ribosome assembly and surface structure biogenesis in Salmonella enterica serovar Typhimurium

The bactericidal/permeability-increasing protein (BPI)-inducible protein A (BipA) is a highly conserved protein in Gram-negative bacteria that is structurally similar to translational GTPases such as IF2, EF-Tu, and EF-G. Our previous research showed that deleting bipA in Escherichia coli at 20°C leads to a defect in 50S ribosomal assembly and impaired lipopolysaccharide (LPS) synthesis. This LPS defect activates the Regulator of Capsule Synthesis (Rcs) pathway, resulting in an overproduction of capsular polysaccharides, a reduction in biofilm formation, and decreased flagella-mediated motility. In this study, we aimed to elucidate the role of BipA in the pathogenicity of Salmonella enterica serovar Typhimurium. We constructed bipA deletion mutants in two pathogenic S. Typhimurium strains, SL1344 and 14028, as well as in the attenuated strain LT2. Our ribosome profiling experiments using the mutant S. Typhimurium strains revealed a defect in ribosome assembly at 20°C, with the accumulation of abnormal 50S ribosomal subunits. We further demonstrated that the absence of BipA in S. Typhimurium impaired LPS biosynthesis at 20°C, compromising membrane integrity and presumably activating the Rcs pathway. This activation altered virulence factors, including reduced biofilm formation, particularly in the 14028ΔbipA strain. Furthermore, the SL1344ΔbipA and 14028ΔbipA strains exhibited significantly decreased swimming motility at 20°C compared to 37°C, confirmed by microscopic observation showing fewer flagella at 20°C. Subsequently, both strains exhibited a significant reduction in invasion capability and cytotoxicity toward human intestinal epithelial cells (HCT116). This functional attenuation was corroborated by the decrease in virulence observed in the 14028ΔbipA strain in a mouse model. Our findings suggest that, in S. Typhimurium, BipA functions as a bacterial fitness factor, contributing to ribosome assembly, LPS synthesis, and virulence-related processes, particularly under stress conditions relevant to host environments.

Reduction of neutrophil extracellular traps accelerates inflammatory resolution and increases bone formation on titanium implants

Neutrophils are the most abundant immune cells in the blood and the first cells to be recruited to the biomaterial implantation site. Neutrophils are fundamental in recruiting mononuclear leukocytes to mount an immune response at the injury site. Neutrophils exert significant pro-inflammatory effects through the release of cytokines and chemokines, degranulation and release of myeloperoxidase (MPO) and neutrophil elastase (NE), and the production of large DNA-based networks called neutrophil extracellular traps (NETs). Neutrophils are initially recruited and activated by cytokines and pathogen- and damage-associated molecular patterns, but little is known about how the physicochemical composition of the biomaterial affects their activation. This study aimed to understand how ablating neutrophil mediators (MPO, NE, NETs) affected macrophage phenotype in vitro and osseointegration in vivo. We discovered that NET formation is a crucial mediator of pro-inflammatory macrophage activation, and inhibition of NET formation significantly suppresses macrophage pro-inflammatory phenotype. Furthermore, reducing NET formation accelerated the inflammatory phase of healing and produced greater bone formation around the implanted biomaterial, suggesting that NETs are essential regulators of biomaterial integration. Our findings emphasize the importance of the neutrophil response to implanted biomaterials and highlight innate immune cells' regulation and amplification signaling during the initiation and resolution of the inflammatory phase of biomaterial integration. STATEMENT OF SIGNIFICANCE: Neutrophils are the most abundant immune cells in blood and are the first to be recruited to the injury/implantation site where they exert significant pro-inflammatory effects. This study aimed to understand how ablating neutrophil mediators affected macrophage phenotype in vitro and bone apposition in vivo. We found that NET formation is a crucial mediator of pro-inflammatory macrophage activation. Reducing NET formation accelerated the inflammatory phase of healing and produced greater appositional bone formation around the implanted biomaterial, suggesting that NETs are essential regulators of biomaterial integration.

Immune cell response to orthopedic and craniofacial biomaterials depends on biomaterial composition

Materials for craniofacial and orthopedic implants are commonly selected based on mechanical properties and corrosion resistance. The biocompatibility of these materials is typically assessed in vitro using cell lines, but little is known about the response of immune cells to these materials. This study aimed to evaluate the inflammatory and immune cell response to four common orthopedic materials [pure titanium (Ti), titanium alloy (TiAlV), 316L stainless steel (SS), polyetheretherketone (PEEK)]. Following implantation into mice, we found high recruitment of neutrophils, pro-inflammatory macrophages, and CD4+ T cells in response to PEEK and SS implants. Neutrophils produced higher levels of neutrophil elastase, myeloperoxidase, and neutrophil extracellular traps in vitro in response to PEEK and SS than neutrophils on Ti or TiAlV. Macrophages co-cultured on PEEK, SS, or TiAlV increased polarization of T cells towards Th1/Th17 subsets and decreased Th2/Treg polarization compared to Ti substrates. Although SS and PEEK are considered biocompatible materials, both induce a more robust inflammatory response than Ti or Ti alloy characterized by high infiltration of neutrophils and T cells, which may cause fibrous encapsulation of these materials. STATEMENT OF SIGNIFICANCE: Materials for craniofacial and orthopedic implants are commonly selected based on their mechanical properties and corrosion resistance. This study aimed to evaluate the immune cell response to four common orthopedic and craniofacial biomaterials: pure titanium, titanium-aluminum-vanadium alloy, 316L stainless steel, and PEEK. Our results demonstrate that while the biomaterials tested have been shown to be biocompatible and clinically successful, the inflammatory response is largely driven by chemical composition of the biomaterials.

Plasma proteomic changes in response to surgical trauma and a novel transdermal analgesic treatment in dogs

Assessment of pain responses and inflammation during animal surgery is difficult because traditional methods, such as visual analogue scores, are not applicable while under anaesthesia. Acute phase proteins (APPs), such as C-reactive protein and haptoglobin, that are typically monitored in veterinary research, do not show a significant change until at least 2 h post-surgery and therefore, immediate pathophysiological changes are uncertain. The current study used sequential window acquisition of all theoretical mass spectra (SWATH-MS) to investigate plasma proteome changes that occur immediately following surgery in dogs and also to assess the efficacy of a novel transdermal ketoprofen (TK) formulation. Castration was chosen as surgical model in this study. The procedure was performed on twelve dogs (n = 6 in two groups) and blood samples were collected at 0 h, 1 and 2 h after surgery for proteomic analysis. Following surgery, there was a general downregulation of proteins, including complement C- 3, complement factor B, complement factor D, transthyretin, and proteins associated with lipid, cholesterol, and glucose metabolisms, reflecting the systemic response to surgical trauma. Many of these changes were diminished in the transdermal group (TD) since ketoprofen, a non-steroidal anti-inflammatory drug (NSAID), inhibits prostanoids and the associated chemotactic neutrophil migration to site of tissue injury. SIGNIFICANCE: SWATH-MS Proteomic analysis revealed significant changes in plasma proteins, predominantly involved in early acute phase and inflammatory response at 1 & 2 h after surgery in castrated dogs. Pre-operative application of transdermal ketoprofen formulation had reduced the systemic immune response, which was confirmed by negligible alteration of proteins in transdermal treated group. A key outcome of this experiment was studying the efficacy of a novel transdermal NSAID formulation in dogs.

A Novel Hypothetical Approach to Explain the Mechanisms of Pathogenicity of Rheumatic Arthritis

The autoimmune disorder rheumatoid arthritis (RA) is a relapsing and chronic inflammatory disease that affects the synovial cells, cartilage, bone, and muscle. It is characterised by the accumulation of huge numbers of polymorphonuclear neutrophils (PMNs) and macrophages in the synovia. Auto-antibodies are deposited in the joint via the activity of highly cationic histones released from neutrophil extracellular traps (NETs) in a phenomenon termed NETosis. The cationic histones function as opsonic agents that bind to negatively charged domains in autoantibodies and complement compounds via strong electrostatic forces, facilitating their deposition and endocytosis by synovial cells. However, eventually the main cause of tissue damage is the plethora of toxic pro-inflammatory substances released by activated neutrophils recruited by cytokines. Tissue damage in RA can also be accompanied by infections which, upon bacteriolysis, release cell-wall components that are toxic to tissues. Some amelioration of the damaged cells and tissues in RA may be achieved by the use of highly anionic heparins, which can neutralize cationic histone activity, provided that these polyanions are co-administrated with anti-inflammatory drugs such as steroids, colchicine, or methotrexate, low molecular weight antioxidants, proteinase inhibitors, and phospholipase A2 inhibitors.

Impact of Smoking on Neutrophil Enzyme Levels in Gingivitis: A Case-Control Study

Background: The determination of the impact of risk factors such as smoking in periodontal disease development is of importance to better characterize the disease. However, its impact on host response remains unclear. This study aimed to evaluate the effects of tobacco smoking on GCF levels of neutrophil enzymes (myeloperoxidase (MPO), beta-glucuronidase (BGD), neutrophil elastase (NE) and periodontal parameters in healthy young adults with dental plaque biofilm-induced gingivitis. Methods: The study population consisted of 60 systemically healthy young adults (39 smokers (Sm) and 21 non-smokers (n-Sm)) diagnosed with plaque-induced gingivitis. The periodontal examination consisted of a plaque index (PI); gingival index (GI); probing depth (PD); bleeding on probing (BoP), and clinical attachment level (CAL). GCF MPO, BGD, and NE levels were determined by means of an enzyme-linked immunosorbent assay (ELISA). Results: PI, GI, and BoP were significantly increased in the Sm group (p < 0.05). PD and CAL showed no significant difference between Sm and n-Sm groups (p > 0.05). In GCF, MPO, BGD, and NE levels were significantly increased in Sm group (p < 0.05). NE levels showed a significant correlation with GI and BoP (p < 0.05 for both). Moreover, a positive correlation between BGD and NE levels (p < 0.05) was measured. Conclusions: It may be concluded that, even in young patients, tobacco consumption affects the host’s immune response related to gingival inflammation. It is, therefore, mandatory to inform young patients about the risk related to tobacco consumption for their gingival health.

Neutrophil: An emerging player in the occurrence and progression of metabolic associated fatty liver disease

Metabolic-associated fatty liver disease (MAFLD) is a common type of chronic liver disease characterized by excessive lipid accumulation in hepatocytes, but the pathogenesis is still unclear. Neutrophils, the most abundant immune cells in the human body, defend against pathogens and regulate the inflammatory response. Recent studies have indicated that excessive liver infiltration of neutrophils is a significant histological hallmark of MAFLD, and neutrophils and their derived granule proteins participate in different stages of MAFLD, including hepatic steatosis, inflammation, fibrosis, cirrhosis and hepatocellular carcinoma. Hence, in this review, we summarize the role of neutrophils in the occurrence and progression of MAFLD and provide a perspective for the clinical application of neutrophils in MAFLD diagnosis and treatment.

Anti-inflammatory, antioxidant effects, and bioaccessibility of Tigzirt propolis

This work aims to assess the anti-inflammatory effects of Tigzirt propolis native to Algeria. We divided 48 male Wistar rats into 8 groups. We orally administered ethyl acetate extract of propolis (EAP), pure polyphenols compounds, or diclofenac 5 days before induction of inflammation by of carrageenan (100 μg/ml, i.p.). We determined the development of paw edema, biological parameters, myeloperoxidase activity, TNF-α, and prostaglandin E2 and measured the oxidative status parameters, as well. Finally, we analyzed the absorption and bioaccessibility of propolis in rats' plasma using GC-MS after orally dosing rats (250 mg/kg). The pretreatment by 200 and 250 mg/kg of propolis significantly reduced the edema rates after the third hour. Propolis can restore the disruption of homeostasis as well as markers of inflammation induced by carrageenan in Wistar rats, and an increase of the enzymatic activities. Furthermore, the inflammation was better resolved in rats that received propolis than in those treated with pure polyphenols. PRACTICAL APPLICATIONS: Propolis is a natural mixture that bees produce by mixing gathered resin and gums to bee saliva and wax. Our research investigated the effect of Tigzirt propolis on the inhibition of biomarkers of inflammation and the development of paw edema. Propolis extract helped to reduce PGE2, TNF-α, myeloperoxidase, and malondialdehyde levels and increase the total antioxidant levels in plasma. Our findings emphasized the use of phenolic extract of propolis in industries such as nutraceuticals for the prevention of inflammatory diseases. It can also protect the body against damage under oxidative stress.

Human Umbilical Cord Mesenchymal Stem Cells Extricate Bupivacaine-Impaired Skeletal Muscle Function via Mitigating Neutrophil-Mediated Acute Inflammation and Protecting against Fibrosis

Skeletal muscle injury presents a challenging traumatological dilemma, and current therapeutic options remain mediocre. This study was designed to delineate if engraftment of mesenchymal stem cells derived from umbilical cord Wharton's jelly (uMSCs) could aid in skeletal muscle healing and persuasive molecular mechanisms. We established a skeletal muscle injury model by injection of myotoxin bupivacaine (BPVC) into quadriceps muscles of C57BL/6 mice. Post BPVC injection, neutrophils, the first host defensive line, rapidly invaded injured muscle and induced acute inflammation. Engrafted uMSCs effectively abolished neutrophil infiltration and activation, and diminished neutrophil chemotaxis, including Complement component 5a (C5a), Keratinocyte chemoattractant (KC), Macrophage inflammatory protein (MIP)-2, LPS-induced CXC chemokine (LIX), Fractalkine, Leukotriene B4 (LTB4), and Interferon-γ, as determined using a Quantibody Mouse Cytokine Array assay. Subsequently, uMSCs noticeably prevented BPVC-accelerated collagen deposition and fibrosis, measured by Masson's trichrome staining. Remarkably, uMSCs attenuated BPVC-induced Transforming growth factor (TGF)-β1 expression, a master regulator of fibrosis. Engrafted uMSCs attenuated TGF-β1 transmitting through interrupting the canonical Sma- And Mad-Related Protein (Smad)2/3 dependent pathway and noncanonical Smad-independent Transforming growth factor beta-activated kinase (TAK)-1/p38 mitogen-activated protein kinases signaling. The uMSCs abrogated TGF-β1-induced fibrosis by reducing extracellular matrix components including fibronectin-1, collagen (COL) 1A1, and COL10A1. Most importantly, uMSCs modestly extricated BPVC-impaired gait functions, determined using CatWalk™ XT gait analysis. This work provides several innovative insights into and molecular bases for employing uMSCs to execute therapeutic potential through the elimination of neutrophil-mediated acute inflammation toward protecting against fibrosis, thereby rescuing functional impairments post injury.

In silico prediction of MicroRNA role in regulation of Zebrafish (Danio rerio) responses to nanoparticle exposure

The release of nanoparticles to the environment can affect health of the exposed organisms. MicroRNAs have been suggested as potential toxicology biomarkers, however the information about use of microRNA in aquatic organisms exposed to nanoparticles (NP) is limited. In silico analysis from publicly available gene expression data was performed. Data selection for the analysis was based on reported biological and pathological outcomes of NP induced toxicity in zebrafish. After identifying relevant genes, we constructed six miRNA-mRNA regulatory networks involved in nanoparticle induced toxicological responses in zebrafish. Based on our prediction and selection criteria we selected six miRNAs that overlapped in constructed networks with remarkable prediction score, and were validated by previous mammalian and zebrafish microRNA profiling studies: dre-miR-124, -144, -148, -155, -19a, -223. The results of this in silico analysis indicate that several highly conserved miRNAs likely have a regulatory role of organismal responses to nanoparticles, and can possibly be used as biomarkers of nanotoxicity in studies using zebrafish as model organism One health approaches.

Overproduction of Tenascin-C Driven by Lipid Accumulation in the Liver Aggravates Hepatic Ischemia/Reperfusion Injury in Steatotic Mice

The purpose of this study was to assess the significance of tenascin-C (Tnc) expression in steatotic liver ischemia/reperfusion injury (IRI). The critical shortage in donor organs has led to the use of steatotic livers in transplantation regardless of their elevated susceptibility to hepatic IRI. Tnc is an endogenous danger signal extracellular matrix molecule involved in various aspects of immunity and tissue injury. In the current study, mice were fed with a steatosis-inducing diet and developed approximately 50% hepatic steatosis, predominantly macrovesicular, before being subjected to hepatic IRI. We report here that lipid accumulation in hepatocytes inflated the production of Tnc in steatotic livers and in isolated hepatic stellate cells. Moreover, we show that the inability of Tnc-/- deficient steatotic mice to express Tnc significantly protected these mice from liver IRI. Compared with fatty controls, Tnc-/- steatotic mice showed significantly reduced serum transaminase levels and enhanced liver histological preservation at both 6 and 24 hours after hepatic IRI. The lack of Tnc expression resulted in impaired lymphocyte antigen 6 complex, locus (Ly6G) neutrophil and macrophage antigen-1 (Mac-1) leukocyte recruitment as well as in decreased expression of proinflammatory mediators (interleukin 1β, tumor necrosis factor α, and chemokine [C-X-C motif] ligand 2) after liver reperfusion. Myeloperoxidase (MPO) is the most abundant cytotoxic enzyme secreted by neutrophils and a key mediator of neutrophil-induced oxidative tissue injuries. Using an in vitro model of steatosis, we also show that Tnc markedly potentiated the effect of steatotic hepatocytes on neutrophil-derived MPO activity. In conclusion, our data support the view that inhibition of Tnc is a promising therapeutic approach to lessen inflammation in steatotic livers and to maximize their successful use in organ transplantation.

Pro-inflammatory agents released by pathogens, dying host cells, and neutrophils act synergistically to destroy host tissues: a working hypothesis

We postulate that the extensive cell and tissue damage inflicted by many infectious, inflammatory and post-inflammatory episodes is an enled result of a synergism among the invading microbial agents, host neutrophils and dead and dying cells in the nidus. Microbial toxins and other metabolites along with the plethora of pro-inflammatory agents released from activated neutrophils massively recruited to the infectious sites and high levels of cationic histones, other cationic peptides, proteinases and Th1 cytokines released from activated polymorphonuclear neutrophils (PMNs) and from necrotized tissues may act in concert (synergism) to bring about cell killing and tissue destruction. Multiple, diverse interactions among the many potential pro-inflammatory moieties have been described in these complex lesions. Such infections are often seen in the skin and aerodigestive tract where the tissue is exposed to the environment, but can occur in any tissue. Commonly, the tissue-destructive infections are caused by group A streptococci, pneumococci, Staphylococcus aureus, meningococci, Escherichia coli and Shigella, although many other microbial species are seen on occasion. All these microbial agents are characterized by their ability to recruit large numbers of PMNs. Given the complex nature of the disease process, it is proposed that, to treat these multifactorial disorders, a "cocktail" of anti-inflammatory agents combined with non-bacteriolytic antibiotics and measures to counteract the critical toxic role of cationic moieties might prove more effective than a strategy based on attacking the bacteria alone.

Inhibitors of elastase stimulate murine B lymphocyte differentiation into IgG- and IgA-producing cells

It is well established that dendritic cells and macrophages play a role in antigen presentation to B and T cells and in shaping B and T cell responses via cytokines they produce. We have previously reported that depletion of neutrophils improves the production of mucosal IgA after sublingual immunization with Bacillus anthracis edema toxin as adjuvant. These past studies also demonstrated that an inverse correlation exists between the number of neutrophils and production of IgA by B cells. Using specific inhibitors of elastase, we addressed whether the elastase activity of neutrophil could be the factor that interferes with production of IgA and possibly other immunoglobulin isotypes. We found that murine splenocytes and mesenteric lymph node cells cultured for 5 days in the presence of neutrophil elastase inhibitors secreted higher levels of IgG and IgA than cells cultured in the absence of inhibitors. The effect of the inhibitors was dose-dependent and was consistent with increased frequency of CD138⁺ cells expressing IgG or IgA. Finally, neutrophil elastase inhibitors increased transcription of mRNA for AID, IL-10, BAFF and APRIL, factors involved in B cell differentiation. These findings identify inhibitors of elastase as potential adjuvants for increasing production of antibodies.

The Influenza Virus Protein PB1-F2 Increases Viral Pathogenesis through Neutrophil Recruitment and NK Cells Inhibition

The influenza A virus (IAV) PB1-F2 protein is a virulence factor contributing to the pathogenesis observed during IAV infections in mammals. In this study, using a mouse model, we compared the host response associated with PB1-F2 with an early transcriptomic signature that was previously associated with neutrophils and consecutively fatal IAV infections. This allowed us to show that PB1-F2 is partly involved in neutrophil-related mechanisms leading to death. Using neutropenic mice, we confirmed that the harmful effect of PB1-F2 is due to an excessive inflammation mediated by an increased neutrophil mobilization. We identified the downstream effects of this PB1-F2-exacerbated neutrophil recruitment. PB1-F2 had no impact on the lymphocyte recruitment in the airways at day 8 pi. However, functional genomics analysis and flow cytometry in broncho-alveolar lavages at 4 days pi revealed that PB1-F2 induced a NK cells deficiency. Thus, our results identify PB1-F2 as an important immune disruptive factor during the IAV infection.

Nebraska Red: a phosphinate-based near-infrared fluorophore scaffold for chemical biology applications

A series of novel phosphinate-based dyes displaying near-infrared fluorescence (NIR) are reported. These dyes exhibit remarkable photostability and brightness. The phosphinate functionality is leveraged as an additional reactive handle in order to tune cell permeability as well as provide a proof-of-principle for a self-reporting small molecule delivery vehicle.

Fine-tuning neutrophil activation: Strategies and consequences

In spite of their important role in host defense, neutrophils can also cause severe morbidity and mortality. Neutrophils have an extensive armory necessary to eradicate pathogens, but neutrophil infiltration and activation also induces major tissue injury associated with acute and chronic inflammatory disorders. Here, we review neutrophil anti-microbial functions and discuss their individual contribution to disease pathogenesis. Furthermore, we provide an overview of the anti-inflammatory drugs that can dampen neutrophil transmigration, elastase activity, and the production of reactive oxygen species which are already in clinical trials. The discovery of potential inhibitors of the release of neutrophil extracellular trap is still in its infancy. Here, we discuss small molecule inhibitors and inhibitory receptors that show promising results in reducing neutrophil extracellular trap formation in vitro and in vivo and discuss the advantages and drawbacks of inhibiting the release of neutrophil extracellular traps as a therapeutic treatment. Specific suppression of neutrophil extracellular trap formation, preferably while other antimicrobial functions are preserved, would be an ideal approach to treat neutrophilic inflammation, since it prevents acute as well as chronic neutrophil-associated pathology.

Increased expression of low density granulocytes in juvenile-onset systemic lupus erythematosus patients correlates with disease activity

Neutrophils are implicated in a wide range of non-infectious inflammatory conditions. A subset of neutrophils in the peripheral circulation of systemic lupus erythematosus (SLE) patients has been described and termed low density granulocytes (LDGs). This study investigates the expression of LDG in juvenile-onset SLE (JSLE) patients compared to controls, and any correlations with disease activity.Neutrophils and LDGs were isolated from JSLE (n = 13) and paediatric non-inflammatory control patients (n = 12). Cell populations were assessed and compared using flow cytometry and morphological analysis. Standard clinical data, which included disease activity markers/scores, were collected for each patient.Significantly increased LDG expression (%mean ± SEM, range) was observed in JSLE patients (10.4 ± 3.26, 3.41-36.3) compared to controls (2.4 ± 0.44, 0.36-5.27; p = 0.005). A statistically significant positive correlation was observed between LDG expression and the British Isles Lupus Activity Group (correlation coefficient 0.685; p = 0.010) and SLE Disease Activity Index (correlation coefficient 0.567; p = 0.043) and the biomarker of dsDNA-antibodies (correlation coefficient 0.590; p = 0.043).Here we observe increased expression in LDGs in JSLE patients, which correlate with dsDNA antibody concentration and scores of disease activity. These correlations indicate that the increased LDG expression observed in this study may have a potential role in the pathogenesis of JSLE, and may be a useful biomarker.

The novel strategy of glucocorticoid drug development via targeting nongenomic mechanisms

Glucocorticoids (GCs) are widely used in clinical practice as potent anti-inflammatory and immunosuppressive agents. Unfortunately, they can also produce numerous and potentially serious side effects that limit their usage. This problem represents the driving force for the intensive search for novel GCs with a better benefit-risk ratio compared to conventional GCs. GCs are believed to take effects mainly through classical genomic mechanisms, which are also largely responsible for GCs' side effects. However, in addition to these genomic effects, GCs also demonstrate rapid genomic-independent activities. It has become increasingly evident that some of the anti-inflammatory, immunosuppressive, anti-allergic and anti-shock effects of GCs could be mediated through nongenomic mechanisms. Thus, theoretically, trying to use nongenomic mechanisms of GCs more intensively may represent a novel strategy for development of GCs with low side effect profile. The new GCs' drugs will take clinical effects mainly via nongenomic mechanisms and do not execute the classical genomic mechanism to reduce side effects.

Analysis of Gene Expression in Experimental Pressure Ulcers in the Rat with Special Reference to Inflammatory Cytokines

Pressure ulcers have been investigated in a few animal models, but the molecular mechanisms of pressure ulcers are not well understood. We hypothesized that pressure results in up-regulation of inflammatory cytokines and those cytokines contribute to the formation of pressure ulcers. We measured genome-wide changes in transcript levels after compression, and focused especially on inflammatory cytokines. The abdominal wall of rats was compressed at 100 mmHg for 4 hours by two magnets. Specimens were obtained 12 hours, 1, or 3 days after compression, and analyzed by light microscopy, microarray, Real-Time PCR, and ELISA. The skin and subcutaneous tissue in the compressed area were markedly thickened. The microarray showed that numerous genes were up-regulated after the compression. Up-regulated genes were involved in apoptosis, inflammation, oxidative stress, proteolysis, hypoxia, and so on. Real-Time PCR showed the up-regulation of granulocyte-macrophage colony stimulating factor (GM-CSF), interferon γ (IFN-γ), interleukin 1β (IL-1β), interleukin 1 receptor antagonist gene (IL1Ra), interleukin 6 (IL-6), interleukin 10 (IL-10), matrix metalloproteinase 3 (MMP-3), tissue inhibitor of metalloproteinase 1 (TIMP-1), and tumor necrosis factor α (TNF-α) at 12 hours, IFN-γ, IL-6, IL-10, MMP-3, and TIMP-1 at 1 day, and IFN-γ, IL-6, and MMP-3 at 3 days. Some genes from subcutaneous tissue were up-regulated temporarily, and others were kept at high levels of expression. ELISA data showed that the concentrations of IL-1β and IL-6 proteins were most notably increased following compression. Prolonged up-regulation of IL-1β, and IL-6 might enhance local inflammation, and continuous local inflammation may contribute to the pressure ulcer formation. In addition, GM-CSF, IFN-γ, MMP-3, and TIMP-1 were not reported previously in the wound healing process, and those genes may have a role in development of the pressure ulcers. Expression data from Real-Time PCR were generally in good agreement with those of the microarray. Our microarray data were useful for identifying genes involved in pressure ulcer formation. However, the expression levels of the genes didn’t necessarily correspond with protein production. As such, the functions of these cytokines need to be further investigated.

Estrogen alleviates acetic acid-induced gastric or colonic damage via both ERα- and ERβ-mediated and direct antioxidant mechanisms in rats

In order to demonstrate the possible protective effects of estrogen receptor (ER)-α and ERβ receptor subtypes in the pathogenesis of colonic and gastric oxidant damage, experimental ulcer and colitis were induced by acetic acid, and the animals were randomly divided as colitis, ulcer, and their corresponding non-ulcer and non-colitis control groups. Each group of rats was treated intramuscularly with the vehicle, selective ERα agonist propylpyrazole-triol (1 mg/kg), ERβ agonist diarylpropionitrile (1 mg/kg), non-selective ER agonist 17β estradiol (E2; 1 mg/kg), or E2 plus non-selective ER antagonist ICI-182780 (1 mg/kg). The results revealed that induction of ulcer or colitis resulted in systemic inflammation as assessed by increased levels of plasma TNF-α and IL-6 levels. In both tissues, the presence of oxidant damage was verified by histological analysis and elevated myleoperoxidase activity. In the colitis and ulcer groups, both ER agonists and the non-selective E2 reversed the oxidative damage in a similar manner. These findings indicate that estrogen acts via both ERα- and ERβ-mediated and direct antioxidant mechanisms, where both ER subtypes play equal and efficient roles in the anti-inflammatory action of estrogen, in limiting the migration of neutrophils to the inflamed tissue, reducing the release and activation of cytokines and thereby alleviating tissue damage.

Concise Review: Mesenchymal Stem Cells Ameliorate Tissue Injury via Secretion of Tumor Necrosis Factor-α Stimulated Protein/Gene 6

Numerous reports have described therapeutic benefits in various disease models after administration of the adult stem/progenitor cells from bone marrow or other tissues referred to as mesenchymal stem cells/multipotent mesenchymal stromal cells (MSCs). They all showed that one of the important effects of MSCs is to act against excessive inflammatory responses and repair the damaged tissues. The therapeutic benefits of MSCs were initially interpreted by their migration, engraftment, and differentiation into target tissues. However, remarkable anatomical structural repairs and functional improvements were increasingly observed with a small number of or even no MSCs in the injured tissues. This suggests that most beneficial effects are largely due to paracrine secretions or cell-to-cell contacts that have multiple effects involving modulation of inflammatory and immune responses. Currently, the therapeutic benefits of MSCs are in part explained by the cells being activated by signals from injured tissues to express an anti-inflammatory protein, tumor-necrosis-factor-α-induced protein 6. This important mechanism of action has attracted increasing attention, and therefore we conducted this review to summarize the latest research.

Neutrophil migration towards C5a and CXCL8 is prevented by non-steroidal anti-inflammatory drugs via inhibition of different pathways

BACKGROUND AND PURPOSE

Non-steroidal anti-inflammatory drugs (NSAIDs) have been shown to induce PG-independent anti-inflammatory actions. Here, we investigated the role of three different NSAIDs (naproxen, ibuprofen and oxaprozin) on neutrophil responses to CXCL8 and C5a.

EXPERIMENTAL APPROACH

Human neutrophils were isolated from healthy volunteers by dextran and Ficoll-Hypaque density gradients. Neutrophils were pre-incubated with different concentrations (1-100 µM) of NSAIDs or kinase inhibitors. Neutrophil degranulation into supernatants was tested by elisa and zymography. Neutrophil chemotaxis was determined using Boyden chambers. F-actin polymerization was determined by Alexa-Fluor 488-conjugated phalloidin fluorescent assay. Integrin expression was assessed by flow cytometry. The phosphorylation of intracellular kinases was studied by Western blot.

KEY RESULTS

Pretreatment with NSAIDs did not affect neutrophil degranulation, but inhibited neutrophil migration and polymerization of F-actin, in response to CXCL8 and C5a. Pretreatment with different NSAIDs prevented C5a-induced integrin (CD11b) up-regulation, while only ibuprofen reduced CXCL8-induced CD11b up-regulation. Pre-incubation with naproxen or oxaprozin, but not ibuprofen, inhibited the PI3K/Akt-dependent chemotactic pathways. Both endogenous (released in cell supernatants) or exogenous (added to cell cultures) PGE2 did not affect C5a- or CXCL8-induced activities. Short-term incubation with NSAIDs did not affect neutrophil PGE2 release.

CONCLUSION AND IMPLICATIONS

Treatment with NSAIDs reduced C5a- and CXCL8-induced neutrophil migration and F-actin polymerization via different mechanisms. Inhibition by ibuprofen was associated with integrin down-regulation, while naproxen and oxaprozin blocked the PI3K/Akt pathway. Both NSAID actions were independent of COX inhibition and PGE2 release.

From airway inflammation to inflammatory bowel disease: eotaxin-1, a key regulator of intestinal inflammation

Eotaxin-1 (CCL-11) is a potent eosinophil chemoattractant that is considered a major contributor to tissue eosinophilia. Elevated eotaxin-1 levels have been described in various pathologic conditions, ranging from airway inflammation, to Hodgkin lymphoma, obesity and coronary artery disease. The main receptor for eotaxin-1 is CCR3; however, recent evidence indicates that eotaxin-1 may also bind to other receptors expressed by various cell types, suggesting a more widespread regulatory role for eotaxin-1 beyond the recruitment of eosinophils. Eotaxin-1 is also strongly associated with various gastrointestinal (GI) disorders. Although the etiology of inflammatory bowel disease (IBD) is still unknown, eotaxin-1 may play a key role in the development of mucosal inflammation. In this review, we summarize the biological context and effects of eotaxin-1, as well as its potential role as a therapeutic target, with a special focus on gastrointestinal inflammation.

Why do we need nongenomic glucocorticoid mechanisms?

Glucocorticoids (GCs) are a class of steroid hormones that have been known to be involved in various physiological processes and to play a pivotal role in preserving basal and stress-related homeostasis. GCs are also widely used clinically as anti-inflammatory, immunosuppressive, anti-shock drugs. It is believed traditionally that GCs exert most of their effects genomically. In addition to the well-known classical genomic mechanisms, GCs also affect various functions via rapid, nongenomic mechanisms. The therapeutic benefits of nongenomic GC actions have been exploited in clinical medicine, especially with high-dose pulsed glucocorticoid administration. However, it is certainly not the case that the inherent nongenomic glucocorticoid mechanisms evolved only for their clinical utility. Here, we review the recent literature on nongenomic actions of GCs related to stress and the physiological significance of these actions, and we propose reasons why nongenomic mechanisms of GC actions are needed.

Design and synthesis of tryptophan containing dipeptide derivatives as formyl peptide receptor 1 antagonist

Our previous studies identified an Fmoc-(S,R)-tryptophan-containing dipeptide derivative, 1, which selectively inhibited neutrophil elastase release induced by formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) in human neutrophils. In an attempt to improve pharmacological activity, a series of tryptophan-containing dipeptides were synthesized and their pharmacological activities were investigated in human neutrophils. Of these, five compounds 3, 6, 19a, 24a, and 24b exhibited potent and dual inhibitory effects on FMLP-induced superoxide anion (O2˙(-)) generation and neutrophil elastase release in neutrophils with IC50 values of 0.23/0.60, 1.88/2.47, 1.87/3.60, 0.12/0.37, and 1.32/1.03 μM, respectively. Further studies indicated that inhibition of superoxide production in human neutrophils by these dipeptides was associated with the selective inhibition of formyl peptide receptor 1 (FPR1). Furthermore, the results of structure-activity relationship studies concluded that the fragment N-benzoyl-Trp-Phe-OMe (3) was most suitable as a core structure for interaction with FPR1, and may be approved as a lead for the development of new drugs in the treatment of neutrophilic inflammatory diseases. As some of the synthesized compounds exhibited separable conformational isomers, and showed diverse bioactivities, the conformation analysis of these compounds is also discussed herein.

Immune complexes isolated from patients with pulmonary tuberculosis modulate the activation and function of normal granulocytes

Circulating immune complexes (ICs) are associated with the pathogenesis of several diseases. Very little is known about the effect of ICs on the host immune response in patients with tuberculosis (TB). The effects of ICs isolated from patients with TB in modulating the release of calcium, cytokines, and granular proteins were studied in normal granulocytes, as were their chemotactic, phagocytic, and oxidative burst processes. ICs from TB patients induced decreased production of cytokines and platelet-activating factor (PAF) from normal granulocytes. ICs from TB patients also induced enhanced chemotaxis and phagocytosis but caused diminished oxidative burst. This was accompanied by an increased release in intracellular calcium. On the other hand, ICs from TB patients induced increased release of the granular proteins human neutrophil peptides 1 to 3 (HNP1-3). Thus, ICs from patients with TB exhibit a profound effect on granulocyte function with activation of certain effector mechanisms and dampening of others.

Transcriptomic analysis of host immune and cell death responses associated with the influenza A virus PB1-F2 protein

Airway inflammation plays a major role in the pathogenesis of influenza viruses and can lead to a fatal outcome. One of the challenging objectives in the field of influenza research is the identification of the molecular bases associated to the immunopathological disorders developed during infection. While its precise function in the virus cycle is still unclear, the viral protein PB1-F2 is proposed to exert a deleterious activity within the infected host. Using an engineered recombinant virus unable to express PB1-F2 and its wild-type homolog, we analyzed and compared the pathogenicity and host response developed by the two viruses in a mouse model. We confirmed that the deletion of PB1-F2 renders the virus less virulent. The global transcriptomic analyses of the infected lungs revealed a potent impact of PB1-F2 on the response developed by the host. Thus, after two days post-infection, PB1-F2 invalidation severely decreased the number of genes activated by the host. PB1-F2 expression induced an increase in the number and level of expression of activated genes linked to cell death, inflammatory response and neutrophil chemotaxis. When generating interactive gene networks specific to PB1-F2, we identified IFN-γ as a central regulator of PB1-F2-regulated genes. The enhanced cell death of airway-recruited leukocytes was evidenced using an apoptosis assay, confirming the pro-apoptotic properties of PB1-F2. Using a NF-kB luciferase adenoviral vector, we were able to quantify in vivo the implication of NF-kB in the inflammation mediated by the influenza virus infection; we found that PB1-F2 expression intensifies the NF-kB activity. Finally, we quantified the neutrophil recruitment within the airways, and showed that this type of leukocyte is more abundant during the infection of the wild-type virus. Collectively, these data demonstrate that PB1-F2 strongly influences the early host response during IAV infection and provides new insights into the mechanisms by which PB1-F2 mediates virulence.

Influenza A viruses may cause severe respiratory disease. PB1-F2, a viral protein identified in 2001 is suspected to play a role in influenza-related pneumonia. In order to understand the impact of PB1-F2 in the pathogenesis underlying Influenza A virus infection, we engineered a mutant virus unable to express PB1-F2. By the use of high-throughput gene expression assays, we compared the host responses of the wild-type-infected and the PB1-F2 mutant-infected mice. We identified that PB1-F2 expression enhances the immune cell death and inflammatory responses of mice. The inflammatory response mediated by the PB1-F2 expression leads to a massive recruitment of leukocytes within the air spaces, a feature that characterizes the influenza-mediated immunopathology. Our results suggest that PB1-F2 is a virulence factor implicated in the deregulation of the inflammatory response observed in acute influenza virus pneumonia. These data underlie the complexities of virus-host interactions and help us understand by which mechanisms Influenza viruses mediate severe respiratory diseases.

Anthranilic acid-based inhibitors of phosphodiesterase: design, synthesis, and bioactive evaluation

Our previous studies identified two 2-benzoylaminobenzoate derivatives 1, which potently inhibited superoxide (O(2)˙(-)) generation induced by formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) in human neutrophils. In an attempt to improve their activities, a series of anthranilic acid derivatives were synthesized and their anti-inflammatory effects and underlying mechanisms were investigated in human neutrophils. Of these, compounds 17, 18, 46, 49, and 50 showed the most potent inhibitory effect on FMLP-induced release of O(2)˙(-) in human neutrophils with IC(50) values of 0.20, 0.16, 0.15, 0.06, and 0.29 μM, respectively. SAR analysis showed that the activities of most compounds were dependent on the ester chain length in the A ring. Conversely, a change in the linker between the A and B ring from amide to sulfonamide or N-methyl amide, as well as exchanges in the benzene rings (A or B rings) by isosteric replacements were unfavorable. Further studies indicated that inhibition of O(2)˙(-) production in human neutrophils by these anthranilic acids was associated with an elevation in cellular cAMP levels through the selective inhibition of phosphodiesterase 4. Compound 49 could be approved as a lead for the development of new drugs in the treatment of neutrophilic inflammatory diseases.

Allergic rhinitis: an update on disease, present treatments and future prospects

Allergic rhinitis (AR) is an inflammation of nasal mucosa mediated by IgE-associated processes occurring independently, or concurrently with asthma. AR is characterized by sensitization-formation and expression of antigen specific IgE, followed by inflammation in two phases. The early phase response involves cross linking of IgE molecules leading to degranulation of mast cells and release of preformed mediators such as histamine and tryptase, or newly synthesized mediators such as prostaglandins and leukotrienes. The late phase response is predominated by the presence of eosinophils, lymphocytes, cytokines, and adhesion molecules. Newer insights reveal that the whole phenomenon of immunological inflammation is intricately knit with neural pathways, which strongly influence the process. Furthermore, AR can impact psychological health and vice versa. Classical pharmacotherapy of AR includes use of oral or topical antihistamines, oral antileukotrienes, topical corticosteroids, mast cell stabilizers, decongestants, and an anticholinergic agent. Among immunomodulatory treatments, immunotherapy is gaining widespread use, while antibody treatment is restricted mainly to resistant cases. Several small molecules with improved safety profile, or targeting novel mechanisms are in the clinical research. Newer antihistamines and corticosteroids with improved safety profile and antagonists of the prostaglandin D(2) (CRTH2) receptors are likely to be available for clinical use in the near future. Lack of properly validated animal models and complexities associated with clinical evaluation are some of the challenges facing the researchers in AR. Comprehensive understanding of immunological and neurological processes in AR would facilitate the future quest for more effective and safer management of this disease.

Specialized proresolving mediator targets for RvE1 and RvD1 in peripheral blood and mechanisms of resolution

Inflammation when unchecked is associated with many prevalent disorders such as the classic inflammatory diseases arthritis and periodontal disease, as well as the more recent additions that include diabetes and cardiovascular maladies. Hence mechanisms to curtail the inflammatory response and promote catabasis are of immense interest. In recent years, evidence has prompted a paradigm shift whereby the resolution of acute inflammation is a biochemically active process regulated in part by endogenous PUFA (polyunsaturated fatty acid)-derived autacoids. Among these are a novel genus of SPMs (specialized proresolving mediators) that comprise novel families of mediators including lipoxins, resolvins, protectins and maresins. SPMs have distinct structures and act via specific G-protein seven transmembrane receptors that signal intracellular events on selective cellular targets activating proresolving programmes while countering pro-inflammatory signals. An appreciation of these endogenous pathways and mediators that control timely resolution opened a new terrain for therapeutic approaches targeted at stimulating resolution of local inflammation. In the present review, we provide an overview of the biosynthesis and actions of resolvin E1, underscoring its protective role in vascular systems and regulating platelet responses. We also give an overview of newly described resolution circuitry whereby resolvins govern miRNAs (microRNAs), and transcription factors that counter-regulate pro-inflammatory chemokines, cytokines and lipid mediators.

Antimicrobial peptides and pregnancy

Antimicrobial peptides (AMPs) are small proteins produced by epithelial surfaces and inflammatory cells, which have broad-spectrum antimicrobial and immunomodulatory activities. They are known to be important in a number of infectious and inflammatory conditions and have been shown to be present in a number of sites throughout the female reproductive tract. Inflammation and infection are associated with a number of complications of pregnancy including preterm labor, and AMPs may play a key role in maintaining and protecting pregnancy. The aim of this review is to describe the expression and function of AMPs in the pregnant female reproductive tract and their relation to preterm labor.

17β-estradiol attenuates exercise-induced neutrophil infiltration in men

17β-estradiol (E2) attenuates exercise-induced muscle damage and inflammation in some models. Eighteen men completed 150 eccentric contractions after random assignment to placebo (Control group) or E2 supplementation (Experimental group). Muscle biopsies and blood samples were collected at baseline, following 8-day supplementation and 3 h and 48 h after exercise. Blood samples were analyzed for sex hormone concentration, creatine kinase (CK) activity and total antioxidant capacity. The mRNA content of genes involved in lipid and cholesterol homeostasis [forkhead box O1 (FOXO1), caveolin 1, and sterol regulatory element binding protein-2 (SREBP2)] and antioxidant defense (SOD1 and -2) were measured by RT-PCR. Immunohistochemistry was used to quantify muscle neutrophil (myeloperoxidase) and macrophage (CD68) content. Serum E2 concentration increased 2.5-fold with supplementation ( P < 0.001), attenuating neutrophil infiltration at 3 h ( P < 0.05) and 48 h ( P < 0.001), and the induction of SOD1 at 48 h ( P = 0.02). Macrophage density at 48 h ( P < 0.05) and SOD2 mRNA at 3 h ( P = 0.01) increased but were not affected by E2. Serum CK activity was higher at 48 h for both groups ( P < 0.05). FOXO1, caveolin 1 and SREBP2 expression were 2.8-fold ( P < 0.05), 1.4-fold ( P < 0.05), and 1.5-fold ( P < 0.001) and higher at 3 h after exercise with no effect of E2. This suggests that E2 attenuates neutrophil infiltration; however, the mechanism does not appear to be lesser oxidative stress or membrane damage and may indicate lesser neutrophil/endothelial interaction.

An in vitro experimental model of neuroinflammation: the induction of interleukin-6 in murine astrocytes infected with Theiler's murine encephalomyelitis virus, and its inhibition by oestrogenic receptor modulators

This paper describes an experimental model of neuroinflammation based on the production of interleukin-6 (IL-6) by neural glial cells infected with Theiler's murine encephalomyelitis virus (TMEV). Production of IL-6 mRNA in mock-infected and TMEV-infected SJL/J murine astrocytes was examined using the Affymetrix murine genome U74v2 DNA microarray. The IL-6 mRNA from infected cells showed an eightfold increase in hybridization to a sequence encoding IL-6 located on chromosome number 5. Quantitative real-time reverse transcription PCR (qPCR) was used to study the regulation of IL-6 expression. The presence of IL-6 in the supernatants of TMEV-infected astrocyte cultures was quantified by ELISA and found to be weaker than in cultures of infected macrophages. The IL-6 was induced by whole TMEV virions, but not by Ad.βGal adenovirus, purified TMEV capsid proteins, or UV-inactivated virus. Two recombinant inflammatory cytokines, IL-1α and tumour necrosis factor-α were also found to be potent inducers of IL-6. The secreted IL-6 was biologically active because it fully supported B9 hybridoma proliferation in a [(3) H]thymidine incorporation bioassay. The cerebrospinal fluid of infected mice contained IL-6 during the acute encephalitis phase, peaking at days 2-4 post-infection. Finally, this in vitro neuroinflammation model was fully inhibited, as demonstrated by ELISA and qPCR, by five selective oestrogen receptor modulators.

Association of genetic variants in complement factor H and factor H-related genes with systemic lupus erythematosus susceptibility

Systemic lupus erythematosus (SLE), a complex polygenic autoimmune disease, is associated with increased complement activation. Variants of genes encoding complement regulator factor H (CFH) and five CFH-related proteins (CFHR1-CFHR5) within the chromosome 1q32 locus linked to SLE, have been associated with multiple human diseases and may contribute to dysregulated complement activation predisposing to SLE. We assessed 60 SNPs covering the CFH-CFHRs region for association with SLE in 15,864 case-control subjects derived from four ethnic groups. Significant allelic associations with SLE were detected in European Americans (EA) and African Americans (AA), which could be attributed to an intronic CFH SNP (rs6677604, in intron 11, P(meta) = 6.6×10(-8), OR = 1.18) and an intergenic SNP between CFHR1 and CFHR4 (rs16840639, P(meta) = 2.9×10(-7), OR = 1.17) rather than to previously identified disease-associated CFH exonic SNPs, including I62V, Y402H, A474A, and D936E. In addition, allelic association of rs6677604 with SLE was subsequently confirmed in Asians (AS). Haplotype analysis revealed that the underlying causal variant, tagged by rs6677604 and rs16840639, was localized to a ~146 kb block extending from intron 9 of CFH to downstream of CFHR1. Within this block, the deletion of CFHR3 and CFHR1 (CFHR3-1Δ), a likely causal variant measured using multiplex ligation-dependent probe amplification, was tagged by rs6677604 in EA and AS and rs16840639 in AA, respectively. Deduced from genotypic associations of tag SNPs in EA, AA, and AS, homozygous deletion of CFHR3-1Δ (P(meta) = 3.2×10(-7), OR = 1.47) conferred a higher risk of SLE than heterozygous deletion (P(meta) = 3.5×10(-4), OR = 1.14). These results suggested that the CFHR3-1Δ deletion within the SLE-associated block, but not the previously described exonic SNPs of CFH, might contribute to the development of SLE in EA, AA, and AS, providing new insights into the role of complement regulators in the pathogenesis of SLE.

Cellular localization of nuclear antigen during neutrophil apoptosis: mechanism for autoantigen exposure?

Juvenile-onset systemic lupus erythematosus (JSLE) is a multisystem autoimmune disease characterized by hyperactive B-cells producing auto-antibodies directed against nuclear antigens. A potential source of these antigenic components is apoptotic cells. We have previously demonstrated increased dysregulated neutrophil apoptosis in JSLE patients. Here we investigate autoantigen expression on JSLE neutrophils during apoptosis. Neutrophils from non-inflammatory controls and JSLE patients were incubated with JSLE and control serum. Apoptosis and dsDNA expression was measured using flow cytometry and confocal microscopy. Increased neutrophil apoptosis and dsDNA expression was observed in JSLE and control neutrophils incubated with JSLE serum. During neutrophil apoptosis nuclear material was exposed on the cell surface rather than within the cell as seen with viable neutrophils. The increased neutrophil apoptosis induced by JSLE compared with control serum resulted in increased surface expression of nuclear antigens. This may provide an additional mechanism leading to the generation of autoantibodies in JSLE.

Specialized pro-resolving lipid mediators in the inflammatory response: An update

A new genus of specialized pro-resolving mediators (SPM) which include several families of distinct local mediators (lipoxins, resolvins, protectins, and maresins) are actively involved in the clearance and regulation of inflammatory exudates to permit restoration of tissue homeostasis. Classic lipid mediators that are temporally regulated are formed from arachidonic acid, and novel local mediators were uncovered that are biosynthesized from ω-3 poly-unsaturated fatty acids, such as eicosapentaenoic acid, docosapentaenoic acid and docosahexaenoic acid. The biosynthetic pathways for resolvins are constituted by fatty acid lipoxygenases and cyclooxygenase-2 via transcellular interactions established by innate immune effector cells which migrate from the vasculature to inflamed tissue sites. SPM provide local control over the execution of an inflammatory response towards resolution, and include recently recognized actions of SPM such as tissue protection and host defense. The structural families of the SPM do not resemble classic eicosanoids (PG or LT) and are novel structures that function uniquely via pro-resolving cellular and molecular targets. The extravasation of inflammatory cells expressing SPM biosynthetic routes are matched by the temporal provision of essential fatty acids from circulation needed as substrate for the formation of SPM. The present review provides an update and overview of the biosynthetic pathways and actions of SPM, and examines resolution as an integrated component of the inflammatory response and its return to homeostasis via biochemically active resolution mechanisms.

Differential expression of factors involved in the intrinsic and extrinsic apoptotic pathways in juvenile systemic lupus erythematosus

Dysregulated neutrophil apoptosis may result in the development of autoimmune disease by contributing to nuclear autoantigen exposure, leading to autoantibody generation and a breakdown in immune tolerance. It has previously been shown that neutrophil apoptosis is increased in juvenile-onset systemic lupus erythematosus (JSLE). This study aims to investigate the pathways involved in JSLE serum-induced apoptosis. Caspases 3, 7–9, IAP1/2, XIAP and FADD mRNA levels and TRAIL R2, BID/tBID, caspase 8 and 9 protein expression were measured in neutrophils from JSLE patients ( n = 14) and controls ( n = 10). The mRNA levels of caspases 7–9 were significantly higher in JSLE neutrophils than in controls, whereas the mRNA levels of IAP1, IAP2 and XIAP were decreased ( p < 0.05). A decrease in neutrophil apoptosis induced by JSLE serum was observed in the presence of caspase 8 and 9 inhibitors ( p < 0.05), and the activity of caspases 8 and 9 increased over time. tBID protein expression increased following incubation with JSLE serum. These data focus specifically on the expression and activity of the main caspases in the intrinsic and extrinsic apoptotic pathways. Increased expression of factors involved in the downstream signalling of the extrinsic apoptotic pathway indicates a prominent involvement of this pathway in JSLE serum-induced apoptosis.