Priming effects of GM-CSF, IFN-gamma and TNF-alpha on human neutrophil inflammatory cytokine production

A Selective ALDH1A3 Inhibitor Impairs Mesothelioma 3-D Multicellular Spheroid Growth and Neutrophil Recruitment

Aldehyde dehydrogenase 1A3 (ALDH1A3), one of the three members of the aldehyde dehydrogenase 1A subfamily, has been associated with increased progression and drug resistance in various types of solid tumours. Recently, it has been reported that high ALDH1A3 expression is prognostic of poor survival in patients with malignant pleural mesothelioma (MPM), an asbestos-associated chemoresistant cancer. We treated MPM cells, cultured as multicellular spheroids, with NR6, a potent and highly selective ALDH1A3 inhibitor. Here we report that NR6 treatment caused the accumulation of toxic aldehydes, induced DNA damage, CDKN2A expression and cell growth arrest. We observed that, in CDKN2A proficient cells, NR6 treatment induced IL6 expression, but abolished CXCL8 expression and IL-8 release, preventing both neutrophil recruitment and generation of neutrophil extracellular traps (NETs). Furthermore, we demonstrate that in response to ALDH1A3 inhibition, CDKN2A loss skewed cell fate from senescence to apoptosis. Dissecting the role of ALDH1A3 isoform in MPM cells and tumour microenvironment can open new fronts in the treatment of this cancer.

Encapsulated saponin by ferritin nanoparticles attenuates the murine pneumococcal pneumonia

Streptococcus pneumonia is classified as a gram-positive bacterial pathogen that causes asymptomatic or symptomatic respiratory infections. This study aimed to evaluate the effects of designed encapsulated saponin by ferritin nanoparticles in the healing progression of experimental bacterial pneumonia. The saponin encapsulated by ferritin followed the disassembly-reassembly process. Pneumonia was induced by the preparation of Streptococcus pneumonia. A total of 50 NMRI mice were divided into control, pneumonia, pneumonia + ferritin, pneumonia + saponin, and pneumonia + encapsulated saponin by ferritin nanoparticles (Nano Saponin) groups. ELISA, Real-time PCR, and Western blotting were used to measure sera IL-4 level, tumor necrosis factor-alpha (Tnf-α), and protein cyclooxygenase-2 (COX-2) gene expression, respectively. COX-2 protein expression, Tnf-α gene expression, and serum levels of IL-4 reduced compared to the pneumonia group. The histopathology results revealed that the rates of inflammation, mucus secretion, pulmonary hemorrhage, thickening of the alveoli wall, and secretion of inflammatory cells were lower in the Nano Saponin group than in the other groups. This study suggests that Glycyrrhiza glabra saponin and encapsulated saponin by ferritin nanoparticles oral consumption with anti-Tnf-α effect besides decreasing protein expression of COX-2 allows mice with pneumonia to recover.

Inflammation induces pro-NETotic neutrophils via TNFR2 signaling

Cytokines released during chronic inflammatory diseases induce pro-inflammatory properties in polymorphonuclear neutrophils (PMNs). Here, we describe the development of a subgroup of human PMNs expressing CCR5, termed CCR5⁺ PMNs. Auto- and paracrine tumor necrosis factor (TNF) signaling increases intracellular neutrophil elastase (ELANE) abundance and induces neutrophil extracellular traps formation (NETosis) in CCR5⁺ PMNs, and triggering of CCR5 amplifies NETosis. Membranous TNF (mTNF) outside-in signaling induces the formation of reactive oxygen species, known activators of NETosis. In vivo, we find an increased number of CCR5⁺ PMNs in the peripheral blood and inflamed lamina propria of patients with ulcerative colitis (UC). Notably, failure of anti-TNF therapy is associated with higher frequencies of CCR5⁺ PMNs. In conclusion, we identify a phenotype of pro-NETotic, CCR5⁺ PMNs present in inflamed tissue in vivo and inducible in vitro. These cells may reflect an important component of tissue damage during chronic inflammation and could be of diagnostic value.

GM-CSF: A Promising Target in Inflammation and Autoimmunity

The cytokine, granulocyte macrophage-colony stimulating factor (GM-CSF), was firstly identified as being able to induce in vitro the proliferation and differentiation of bone marrow progenitors into granulocytes and macrophages. Much preclinical data have indicated that GM-CSF has a wide range of functions across different tissues in its action on myeloid cells, and GM-CSF deletion/depletion approaches indicate its potential as an important therapeutic target in several inflammatory and autoimmune disorders, for example, rheumatoid arthritis. In this review, we discuss briefly the biology of GM-CSF, raise some current issues and questions pertaining to this biology, summarize the results from preclinical models of a range of inflammatory and autoimmune disorders and list the latest clinical trials evaluating GM-CSF blockade in such disorders.

Potential molecular mechanisms of negative pressure in promoting wound healing

Negative pressure wound therapy (NPWT) has been widely used in various lesions. This study aimed to explore the biological effects of negative pressure on the polymorphonuclear neutrophils (PMNs), macrophages, and epidermal keratinocyte cells involved in wound healing. PMNs differentiated from HL-60, macrophages were derived from THP-1 monocytes, and keratinocytes were cultured in vitro, and they were treated with 0, -0.03 mp, and -0.05 mp, respectively. Cell ultrastructure; viability; apoptosis; and protein factors such as tumour necrosis factor-α (TNF-α), interferon-γ (IFN-γ), epidermal growth factor (EGF), epidermal growth factor receptor (EGFR), interleukin-17 (IL-17), and cell division cycle 42 (Cdc42) were determined by transmission electron microscopy (TEM), CCK8, flow cytometry (FCM), ELISA, and simple Western assays, respectively. After negative pressure stimulation, the cell ultrastructure of PMNs and macrophages cells was presented with a marked increase of lysosomes and a relative decrease of mitochondria. In addition, the cell viability was enhanced in PMNs and macrophages in a pressure-dependent manner and apoptosis ratios were significantly reduced in PMNs and macrophages. In addition, under -0.05 negative pressure, IFN-γ and IL-17 were significantly increased in PMNs or macrophages. Moreover, increased EGF and EGFR and Cdc42 levels in keratinocytes induced by the -0.05 mpa were detected, indicating that the migration chemotaxis of keratinocyte cells was enhanced. Negative pressure might promote cell proliferation, accelerate inflammatory responses, and promote epithelialisation during wound healing by increasing IFN-γ, IL-17, Cdc42, EGF, and EGFR in PMNs, macrophages, or keratinocytes under different negative pressures.

CD40 ligand deficiency causes functional defects of peripheral neutrophils that are improved by exogenous IFN-γ

BACKGROUND

Patients with X-linked hyper-IgM syndrome caused by CD40 ligand (CD40L) deficiency often present with episodic, cyclic, or chronic neutropenia, suggesting abnormal neutrophil development in the absence of CD40L-CD40 interaction. However, even when not neutropenic and despite immunoglobulin replacement therapy, CD40L-deficient patients are susceptible to life-threatening infections caused by opportunistic pathogens, suggesting impaired phagocyte function and the need for novel therapeutic approaches.

OBJECTIVES

We sought to analyze whether peripheral neutrophils from CD40L-deficient patients display functional defects and to explore the in vitro effects of recombinant human IFN-γ (rhIFN-γ) on neutrophil function.

METHODS

We investigated the microbicidal activity, respiratory burst, and transcriptome profile of neutrophils from CD40L-deficient patients. In addition, we evaluated whether the lack of CD40L in mice also affects neutrophil function.

RESULTS

Neutrophils from CD40L-deficient patients exhibited defective respiratory burst and microbicidal activity, which were improved in vitro by rhIFN-γ but not soluble CD40L. Moreover, neutrophils from patients showed reduced CD16 protein expression and a dysregulated transcriptome suggestive of impaired differentiation. Similar to CD40L-deficient patients, CD40L knockout mice were found to have impaired neutrophil responses. In parallel, we demonstrated that soluble CD40L induces the promyelocytic cell line HL-60 to proliferate and mature by regulating the expression of genes of the same Gene Ontology categories (eg, cell differentiation) when compared with those dysregulated in peripheral blood neutrophils from CD40L-deficient patients.

CONCLUSION

Our data suggest a nonredundant role of CD40L-CD40 interaction in neutrophil development and function that could be improved in vitro by rhIFN-γ, indicating a potential novel therapeutic application for this cytokine.

Role of iRhom2 in intestinal ischemia-reperfusion-mediated acute lung injury

Intestinal ischemia-reperfusion (I/R) may cause acute systemic and lung inflammation. However, the detailed mechanism of this inflammatory cascade has not been fully elucidated. Inactive rhomboid protein 2 (iRhom2) is essential for the maturation of TNF-α converting enzyme (TACE), which is required for TNF-α secretion. We evaluated the role of iRhom2 in a mouse model of intestinal I/R using iRhom2 knockout (KO) and wild-type (WT) mice. Lung injury following intestinal I/R was significantly attenuated in iRhom2 KO mice compared with WT mice. After intestinal I/R, lungs from iRhom2 KO mice showed significantly lower myeloperoxidase (MPO) activity and markedly reduced cell apoptosis associated with a decreased level of active caspase 3 and decreased TUNEL staining compared with lungs from WT mice. TNF-α levels were elevated in the serum and lungs of WT mice with intestinal I/R and significantly reduced in iRhom2 KO mice with intestinal I/R. iRhom2 may play a critical role in the pathogenesis of acute lung injury (ALI) after intestinal I/R and thus may be a novel therapeutic target for ALI after intestinal I/R injury.

Multiple Phenotypic Changes Define Neutrophil Priming

Exposure to pro-inflammatory cytokines, chemokines, mitochondrial contents, and bacterial and viral products induces neutrophils to transition from a basal state into a primed one, which is currently defined as an enhanced response to activating stimuli. Although, typically associated with enhanced generation of reactive oxygen species (ROS) by the NADPH oxidase, primed neutrophils show enhanced responsiveness of exocytosis, NET formation, and chemotaxis. Phenotypic changes associated with priming also include activation of a subset of functions, including adhesion, transcription, metabolism, and rate of apoptosis. This review summarizes the breadth of phenotypic changes associated with priming and reviews current knowledge of the molecular mechanisms behind those changes. We conclude that the current definition of priming is too restrictive. Priming represents a combination of enhanced responsiveness and activated functions that regulate both adaptive and innate immune responses.

Rac GTPase Activating Protein ARHGAP25 Regulates Leukocyte Transendothelial Migration in Mice

ARHGAP25 is a Rac-specific GTPase-activating protein that is expressed primarily in hematopoietic cells. The involvement of ARHGAP25 in regulating the recruitment of leukocytes to inflammatory sites was investigated in genetically modified mice. Using intravital microscopy, we show that Arhgap25 deficiency affects all steps of leukocyte recruitment with a predominant enhancement of transendothelial migration of neutrophilic granulocytes. Increased transmigration of Arhgap25-deficient leukocytes is demonstrated in inflamed cremaster muscle venules, in a peritonitis model, and in an in vitro chemotaxis assay. Using bone marrow chimeric mice lacking ARHGAP25 in the hematopoietic compartment, we show that enhanced migration in the absence of ARHGAP25 is due to defective leukocyte function. In search for potential mechanisms of ARHGAP25-regulated migration of neutrophils, we detected an increase in the amount of active, GTP-bound Rac and Rac-dependent cytoskeletal changes in the absence of ARHGAP25, suggesting a critical role of ARHGAP25 in counterbalancing the Rac-activating effect of nucleotide exchange factors. Taken together, using Arhgap25-deficient mice, we identified ARHGAP25 as a relevant negative regulator of leukocyte transendothelial migration.

Investigating the Role of TNF-α and IFN-γ Activation on the Dynamics of iNOS Gene Expression in LPS Stimulated Macrophages

Macrophage produced inducible nitric oxide synthase (iNOS) is known to play a critical role in the proinflammatory response against intracellular pathogens by promoting the generation of bactericidal reactive nitrogen species. Robust and timely production of nitric oxide (NO) by iNOS and analogous production of reactive oxygen species are critical components of an effective immune response. In addition to pathogen associated lipopolysaccharides (LPS), iNOS gene expression is dependent on numerous proinflammatory cytokines in the cellular microenvironment of the macrophage, two of which include interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α). To understand the synergistic effect of IFN-γ and TNF-α activation, and LPS stimulation on iNOS expression dynamics and NO production, we developed a systems biology based mathematical model. Using our model, we investigated the impact of pre-infection cytokine exposure, or priming, on the system. We explored the essentiality of IFN-γ priming to the robustness of initial proinflammatory response with respect to the ability of macrophages to produce reactive species needed for pathogen clearance. Results from our theoretical studies indicated that IFN-γ and subsequent activation of IRF1 are essential in consequential production of iNOS upon LPS stimulation. We showed that IFN-γ priming at low concentrations greatly increases the effector response of macrophages against intracellular pathogens. Ultimately the model demonstrated that although TNF-α contributed towards a more rapid response time, measured as time to reach maximum iNOS production, IFN-γ stimulation was significantly more significant in terms of the maximum expression of iNOS and the concentration of NO produced.

Neutrophils with protumor potential could efficiently suppress tumor growth after cytokine priming and in presence of normal NK cells

In tumor-bearing state, the function of neutrophils is converted from tumor-suppressing to tumor-promoting. Here we report that priming with IFN-γ and TNF-α could convert the potential of neutrophils from tumor-promoting to tumor-suppressing. The neutrophils with protumor potential have not lost their responsiveness to IFN-γ and TNF-α. After priming with IFN-γ and TNF-α, the potential of the neutrophils to express Bv8 and Mmp9 genes was reduced. Conversely, the tumor-promotional neutrophils recovered the expression of Rab27a and Trail, resumed the activation levels of PI3K and p38 MAPK pathways in response to stimuli, and expressed higher levels of IL-18 and NK-activating ligands such as RAE-1, MULT-1, and H60. Therefore, the anti-tumor function of the neutrophils was augmented, including the cytotoxicity to tumor cells, the capability of degranulation, and the capacity to activate NK cells. Since the function of NK cells is impaired in tumor-bearing state, the administration of normal NK cells could significantly augment the efficiency of tumor therapy based on neutrophil priming. These findings highlight the reversibility of neutrophil function in tumor-bearing state, and suggest that neutrophil priming by IFN-γ/TNF-α might be a potential approach to eliminate residual tumor cells in comprehensive strategy for tumor therapy.

Psoriatic keratinocytes prime neutrophils for an overproduction of superoxide anions

Psoriatic plaques result from an abnormal proliferation of keratinocytes associated with the local presence of T lymphocytes and neutrophils. The exact role of neutrophils in psoriatic lesions remains unclear. The present investigation was aimed at deciphering the capacity of psoriatic keratinocytes to alter in vitro functions of neutrophils. Blood neutrophils from healthy donors were incubated with psoriatic (PK) or healthy keratinocytes (HK) with and without IL-2-activated healthy T lymphocytes. The study was focussed on neutrophil capacity of adherence, viability and superoxide anion production. PK or HK with or without T lymphocytes similarly augmented neutrophil viability after 48 h of co-incubation. PK or HK did not directly activate the superoxide production by neutrophils. However, they both primed neutrophils for an increased fMLF-induced production of superoxide, an effect enhanced by the presence of T lymphocytes. PK were 1.5-fold more efficient than HK to augment this superoxide production. PK cultured with T lymphocytes induced the adhesion of neutrophils 4.7 times more efficiently than HK. The adherence of neutrophils was mediated through ICAM-1, LFA-1 and Mac-1, independently of bioactive lipids. The effects of PK and HK on neutrophil viability and priming were independent of direct cellular contact. In conclusion, keratinocytes can impact neutrophils by increasing their lifespan, and by priming them to overproduce superoxide. PK are more efficient than HK in priming neutrophils, an effect enhanced by T lymphocytes. These results indicate that neutrophils could contribute to psoriasis pathogenesis partly through their pathological interactions with PK.

GM-CSF priming drives bone marrow-derived macrophages to a pro-inflammatory pattern and downmodulates PGE2 in response to TLR2 ligands

In response to pathogen recognition by Toll-like receptors (TLRs) on their cell surface, macrophages release lipid mediators and cytokines that are widely distributed throughout the body and play essential roles in host responses. Granulocyte macrophage colony-stimulating factor (GM-CSF) is important for the immune response during infections to improve the clearance of microorganisms. In this study, we examined the release of mediators in response to TLR2 ligands by bone marrow-derived macrophages (BMDMs) primed with GM-CSF. We demonstrated that when stimulated with TLR2 ligands, non-primed BMDMs preferentially produced PGE₂ in greater amounts than LTB₄. However, GM-CSF priming shifted the release of lipid mediators by BMDMs, resulting in a significant decrease of PGE₂ production in response to the same stimuli. The decrease of PGE₂ production from primed BMDMs was accompanied by a decrease in PGE-synthase mRNA expression and an increase in TNF-α and nitric oxide (NO) production. Moreover, some GM-CSF effects were potentiated by the addition of IFN-γ. Using a variety of TLR2 ligands, we established that PGE₂ release by GM-CSF-primed BMDMs was dependent on TLR2 co-receptors (TLR1, TLR6), CD14, MyD88 and the nuclear translocation of NFκB but was not dependent on peroxisome proliferator-activated receptor-γ (PPAR-γ) activation. Indeed, GM-CSF priming enhanced TLR2, TLR4 and MyD88 mRNA expression and phospho-IκBα formation. These findings demonstrate that GM-CSF drives BMDMs to present a profile relevant to the host during infections.

Mechanisms of indirect acute lung injury: a novel role for the coinhibitory receptor, programmed death-1

OBJECTIVE

To determine the contribution of programmed death receptor (PD)-1 in the morbidity and mortality associated with the development of indirect-acute lung injury.

BACKGROUND

The immune cell interaction(s) leading to indirect-acute lung injury are not completely understood. In this respect, we have recently shown that the murine cell surface coinhibitory receptor, PD-1, has a role in septic morbidity/mortality that is mediated in part through the effects on the innate immune arm. However, it is not know if PD-1 has a role in the development of indirect-acute lung injury and how this may be mediated at a cellular level.

METHODS

PD-1 -/- mice were used in a murine model of indirect-acute lung injury (hemorrhagic shock followed 24 hours after with cecal ligation and puncture-septic challenge) and compared to wild type controls. Groups were initially compared for survival and subsequently for markers of pulmonary inflammation, influx of lymphocytes and neutrophils, and expression of PD-1 and its ligand-PD-L1. In addition, peripheral blood leukocytes of patients with indirect-acute lung injury were examined to assess changes in cellular PD-1 expression relative to mortality.

RESULTS

PD-1 -/- mice showed improved survival compared to wild type controls. In the mouse lung, CD4+, CD11c+, and Gr-1+ cells showed increased PD-1 expression in response to indirect-acute lung injury. However, although the rise in bronchial alveolar lavage fluid protein concentrations, lung IL-6, and lung MCP-1 were similar between PD-1 -/- and wild type animals subjected to indirect acute lung injury, the PD-1 -/- animals that were subjected to shock/septic challenge had reduced CD4:CD8 ratios, TNF-α levels, MPO activity, and Caspase 3 levels in the lung. Comparatively, we observed that humans, who survived their acute lung injury, had significantly lower expression of PD-1 on T cells.

CONCLUSIONS

PD-1 expression contributes to mortality after the induction of indirect-acute lung injury and this seems to be associated with modifications in the cellular and cytokine profiles in the lung.

Depletion of NK cells in a murine polytrauma model is associated with improved outcome and a modulation of the inflammatory response

Sepsis and associated diseases such as systemic inflammatory response syndrome and multiple organ dysfunction syndrome represent common posttraumatic complications on intensive care units induced by a variety of body defense mechanisms. Natural killer (NK) cells are part of the innate immune system. They are thought to play an important role in the development of such syndromes by interplay with other immune cell types and subsequent activation of the inflammatory cascade. To test this hypothesis, NK cells were depleted by administration of antimouse asialo-GM1 antibody in a murine polytrauma model consisting of femur fracture, hemorrhagic shock, and subsequent sepsis. Mortality and immune parameters such as cytokine expression in lung and liver, lymphocyte phenotyping, lymphocyte apoptosis, and organ pathology were determined 96 h after sepsis induction. Survival values showed 50% in the control sepsis group and 100% after NK cell depletion. Thus, NK cell depletion resulted in 50% mortality reduction. Furthermore, we found reductions in the inflammatory response, represented by IL-6 expression in liver, and a decrease in infiltrating neutrophils in the liver and lung. In addition, lymphocyte apoptosis in spleen was decreased by depletion of NK cells. Taken together, these data demonstrate that NK cells contribute to the pathogenetic pathways in a murine polytrauma model. One main mechanism of action seems to be the induction of systemic inflammatory events. Thus, depletion of NK cells results in attenuated inflammation and an overall improvement in outcome. Therefore, NK cells can be considered as important targets for therapeutic strategies.

Functional antagonism by GM-CSF on TNF-alpha-induced CD83 expression in human neutrophils

TNFalpha-induced expression of CD83 in leukocytes is mediated by NF-kappab. The aim of our present study was to investigate the underlying mechanism of a unique functional antagonism between GM-CSF and TNFalpha-induced up-regulation of CD83 in human neutrophils. CD83 was down-regulated by co-stimulation of neutrophils with TNFalpha and GM-CSF compared to TNFalpha alone both at the level of mRNA and protein. In marked contrast, the expression of IL-1RA was up-regulated under the same conditions. The down-regulation of CD83 was not mediated by modulation of the NF-kappab signaling pathway. Neither was it mediated by a decrease in mRNA stability of CD83. NF-kappab was modulated under these conditions as both the expression of the target gene IL-1RA as well as the phosphorylation of IkBalpha were up-regulated. Our results show that co-stimulation with pro-inflammatory cytokines such as TNFalpha and GM-CSF can have differential effects on inflammatory pathways initiated in the same target cell. GM-CSF can both synergize with TNFalpha in the case of expression of IL1-RA and antagonize in the case of CD83. Therefore, expression of CD83 as read out for activation of neutrophils in patients with inflammatory diseases is complicated by the presence of cross-modulating cytokines such as GM-CSF.

HIV and other lentiviral infections cause defects in neutrophil chemotaxis, recruitment, and cell structure: immunorestorative effects of granulocyte-macrophage colony-stimulating factor

Patients with HIV infection exhibit deficits in bacterial and fungal clearance, and possibly depressed innate immunity. In this study, we observed that neutrophils from HIV-infected patients have a profound defect in chemotaxis in response to endogenous (IL-8) and bacterial (fMLP) chemoattractants, which was directly correlated with peripheral CD4(+) lymphocyte levels but not plasma viral load. A similar chemotactic defect was observed in the feline immunodeficiency virus (FIV) model of HIV infection. Intravital microscopy of FIV-infected animals revealed marked impairment in the in vivo recruitment of leukocytes; specifically integrin-dependent neutrophil adhesion and emigration induced by bacterial products. Treatment of FIV-infected animals with GM-CSF re-established both neutrophil recruitment (rolling, adhesion, and emigration) and in vitro chemotaxis to the levels seen in uninfected animals. This restoration of neutrophil responses was not due to GM-CSF-mediated priming. Rather, HIV and FIV infections resulted in defective neutrophil development, with an ensuing reduction in neutrophil granularity and chemotactic receptor expression. GM-CSF therapy restored neutrophil granularity, implying restoration of normal neutrophil development. Together, our findings underscore the fundamental defects in innate immunity caused by lentivirus infections, while also indicating that GM-CSF may be a potential immunorestorative therapy for HIV-infected patients.

Anti-neutrophil cytoplasm-associated glomerulonephritis

Wegener's granulomatosis, microscopic polyangiitis, and renal limited vasculitis are associated with circulating anti-neutrophil cytoplasm antibodies and are an important cause of rapidly progressive glomerulonephritis. This review gives an account of recent advances in the understanding of the pathogenesis underlying these conditions and how these may lead to future treatments. Consideration is given to recent clinical trials in the management of anti-neutrophil cytoplasm antibodies (ANCA)-associated vasculitides.

Interrelationship Among Neutrophil Efficiency, Inflammation, Antioxidant Activity and Zinc Pool in Very Old Age

Neutrophils are the first barrier against infections. Aged neutrophils display impaired oxidative burst and phagocytosis with subsequent less capability to destroy bacteria. In successful ageing (nonagenarians), neutrophil efficiency (phagocytosis) increases. After ingested microbes, aged neutrophils are less prone to undergo apoptosis favouring chronic inflammation. Moreover, the superoxide dismutase (SOD) activity, which is necessary in avoiding ROS produced by oxidative burst, is limited in ageing. The mechanisms of age-related changes in neutrophil function are not fully understood, taking also into account that nonagenarians escape infections in comparison with elderly. Zinc pool may be involved because it is pivotal for neutrophil efficiency and SOD activity. Since zinc also controls the inflammation, via IL-6 and soluble factor of gp130 (sgp130), we have assessed the possible interrelationship among oxidative burst, apoptosis, inflammation, SOD, adhesion molecule Mac-1 and zinc pool in elderly and in nonagenarians. The oxidative burst and the capacity to increase Mac-1 after PMA stimulation decrease both in elderly and nonagenarians, but the latter display a slight increased neutrophil induced apoptosis, decreased sgp130, increased SOD, and more neutrophil zinc content, as it occurs in young-adults. Significant correlation exists between sgp130 and zinc pool in very old age. These findings suggest lower chronic inflammation in nonagenarians, via more zinc available, with subsequent long-life survival. Therefore, a more correct interrelationship among neutrophil efficiency, inflammation, antioxidant activity and zinc pool exists in successful ageing with subsequent more effectiveness to control the inflammatory response to pathogens.

Blockade of TNF does not alter oxygen burst and phagocytosis of human neutrophils in patients with rheumatoid arthritis

Clinical trials evaluating tumor necrosis factor alpha (TNF-alpha) binding agents in patients with rheumatoid arthritis (RA) have demonstrated significant efficacy in reducing symptoms of disease and slowing radiographic progression. However, infectious complications are the most severe and common adverse effects of anti-TNF therapy. The functional capacities of neutrophils (PMNs) as the first line of defense in bacterial and fungal infections are enhanced by soluble TNF as a potent neutrophil primer. The aim of this study was to assess the influence of in vivo TNF blockade on oxygen burst (OB) and phagocytosis of human neutrophils. PMNs were derived from 20 patients with RA on anti-TNF-alpha therapy and 13 patients using conventional DMARDs. By flow cytometry we measured OB upon stimulation with Escherichia coli and N-formyl-1-methionyl-1-leucyl-phenylalanine (FMLP) with and without priming with granulocyte-colony stimulating factor (G-CSF) and/or TNF-alpha using dihydrorhodamine (DHR) 123. Phagocytosis of fluorescein isothiocyanate (FITC)-labeled E. coli was also assessed by flow cytometry. Thirty-three healthy volunteers served as controls. Upon stimulation with E. coli and FMLP, there was no significant difference in OB between the two patient groups and healthy controls. Priming was effective in all groups. Phagocytosis of E. coli by PMNs was equally effective in controls and patients independent from the treatment regimen. These data show that OB, phagocytosis and responsiveness to priming with TNF and G-CSF of PMNs are not impaired in patients with RA treated with anti-TNF agents in comparison with patients on conventional DMARDs or healthy controls. Thus, the infectious complications observed in patients with TNF blockade cannot be explained by functional impairment of PMNs; however, the neutralization of TNF as a potent primer of neutrophil response may increase the susceptibility for infections in these patients.

IFN-γ Priming of Chicken Heterophils Upregulates the Expression of Proinflammatory and Th1 Cytokine mRNA Following Receptor-Mediated Phagocytosis ofSalmonella entericaserovarenteritidis

Responsiveness to invasive pathogens, clearance via the inflammatory response, and activation of appropriate acquired responses are all coordinated by innate host defenses. Polymorphonuclear leukocytes (PMNs) are cellular components of innate response, with the primary PMN in poultry being the heterophil. Priming is the potentiation of the phagocyte activation process. Interferon-gamma (IFN-gamma) is a pleiotropic cytokine involved in basically all phases of immune and inflammatory responses that has been shown to prime heterophil functional activities. In the present experiments, using real-time quantitative RT-PCR, we evaluated the role of recombinant chicken IFN-gamma (rChIFN-gamma) as a priming mediator to control heterophil responses at the level of gene transcription and expression of the mRNA for proinflammatory (interleukin-1beta [IL-1beta], IL-6, IL-8) and Th1 (IL-18 and IFN-gamma) cytokine genes following stimulation with phagocytosis agonists, opsonized and nonopsonized Salmonella enteritidis. rChIFN-gamma primed the heterophils for an increase in transcription of proinflammatory cytokines induced by phagocytic agonists but also upregulated expression of Th1 cytokine (IL-18 and IFN-gamma) mRNA and stimulated an increased production of IFN-gamma. Although rChIFN-gamma priming modulated the expression of cytokine mRNA in heterophils stimulated by different phagocytic agonists, rChIFN-gamma by itself did not directly induce gene expression of either proinflammatory or Th1 cytokines. The enhanced expression of cytokine mRNA does not appear to be differentially expressed depending on the receptor activated during phagocytosis. The results from the present experiments suggest that rChIFN-gamma may play a significant role in avian innate immunity against Salmonella infection and may offer an adjunct use in the prevention and treatment of salmonellae infections in newly hatched chickens.

Interferon-gamma activation of polymorphonuclear neutrophil function

As current research illuminates the dynamic interplay between the innate and acquired immune responses, the interaction and communication between these two arms has yet to be fully investigated. Polymorphonuclear neutrophils (PMNs) and interferon-gamma (IFN-gamma) are known critical components of innate and acquired immunity, respectively. However, recent studies have demonstrated that these two components are not entirely isolated. Treatment of PMNs with IFN-gamma elicits a variety of responses depending on stimuli and environmental conditions. These responses include increased oxidative burst, differential gene expression, and induction of antigen presentation. Many of these functions have been overlooked in PMNs, which have long been classified as terminal phagocytic cells incapable of protein synthesis. As this review reports, the old definition of the PMN is in need of an update, as these cells have demonstrated their ability to mediate the transition between the innate and acquired immune responses.

The laminin receptor modulates granulocyte-macrophage colony-stimulating factor receptor complex formation and modulates its signaling

Basement membrane matrix proteins are known to up-regulate granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling in neutrophils and mononuclear phagocytes, but the mechanisms involved are poorly understood. We used the intracellular portion of the alpha subunit of the GM-CSF receptor (alphaGMR) to search for interacting proteins and identified the 67-kDa laminin receptor (LR), a nonintegrin matrix protein receptor expressed in several types of host defense cells and certain tumors, as a binding partner. LR was found to interact with the beta subunit of the GMR (betaGMR) as well. Whereas GM-CSF functions by engaging the alphaGMR and betaGMR into receptor complexes, LR inhibited GM-CSF-induced receptor complex formation. Laminin and fibronectin binding to LR was found to prevent the binding of betaGMR to LR and relieved the LR inhibition of GMR. These findings provide a mechanistic basis for enhancing host defense cell responsiveness to GM-CSF at transendothelial migration sites while suppressing it in circulation.

Induction of metallothionein in human skin by routine exposure to sunlight: evidence for a systemic response and enhanced induction at certain body sites

Expression of metallothionein, an antioxidant induced by a variety of stimuli including ultraviolet light, was quantitated by immunohistochemistry in the skin of males aged over 50 who had known short- and long-term exposures to sunlight. Skin punch biopsies were taken from two sites in each subject: the hand in all subjects and a range of other sites matched to patients with a previously excised primary melanoma. Metallothionein expression (strongest in the basal layers of the epidermis and primarily nuclear) was associated with both short- and long-term exposure to sunlight. A plateau of staining intensity was reached after 3 h sun exposure, within the previous 3 d before biopsy. Expression was also elevated in the nonexposed skin sites of subjects who had recent sun exposure, indicating a systemic response to exposure of remote sites. Using the skin of the hand to normalize responses to chronic exposure between individuals, the systemically modulated response to sunlight was significantly greater on the unexposed back than on other sites. The possibility of ultraviolet-induced cytokines selectively modifying the response of skin on a site-specific basis was investigated. The circulating leukocytes, but not lymphocytes, of two individuals exposed to 1 minimal erythema dose whole-body solar-simulated ultraviolet showed increased interleukin-6 mRNA 4 h after exposure. Interleukin-6 was not directly induced in these cell populations 4 h after ultraviolet A or ultraviolet B irradiation ex vivo. Leukocytes may therefore contribute to and amplify the systemic effects of ultraviolet-induced interleukin-6 and metallothionein expression.