Cytokine expression and release by neutrophils

The utilisation of resolvins in medicine and tissue engineering

Recent advances in the field of regenerative medicine and biomaterial science have highlighted the importance of controlling immune cell phenotypes at the biomaterial interface. These studies have clearly indicated that a rapid resolution of the inflammatory process, mediated by a switch in the macrophage population towards a reparative phenotype, is essential for tissue regeneration to occur. While various biomaterial surfaces have been developed in order to impart immunomodulatory properties to the resulting constructs, an alternative strategy involving the use of reparative biological cues, known as resolvins, is emerging in regenerative medicine. This review reports on the mechanisms via which resolvins participate in the resolution of inflammation and describes their current utilisation in pre-clinical and clinical settings, along with their effectiveness when combined with biomaterial constructs in tissue engineering applications. STATEMENT OF SIGNIFICANCE: The resolution of the inflammatory process is necessary for achieving tissue healing and regeneration. Resolvins are lipid mediators and play a key role in the resolution of the inflammatory response and can be used in as biological cues to promote tissue regeneration. This review describes the various biological inflammatory mechanisms and pathways involving resolvins and how their action results in a pro-healing response. The use of these molecules in the clinical setting is then summarised for various applications along with their limitations. Lastly, the review focuses on the emergence resolvins in tissue engineering products including the use of a more stable form which holds greater prospect for regenerative purposes.

Complex Involvement of Interleukin-26 in Bacterial Lung Infection

Pneumonia is a global cause of mortality, and this provides a strong incentive to improve the mechanistic understanding of innate immune responses in the lungs. Here, we characterized the involvement of the cytokine interleukin (IL)-26 in bacterial lung infection. We observed markedly increased concentrations of IL-26 in lower airway samples from patients with bacterial pneumonia and these correlated with blood neutrophil concentrations. Moreover, pathogen-associated molecular patterns (PAMPs) from both Gram-negative and -positive bacteria increased extracellular IL-26 concentrations in conditioned media from human models of alveolar epithelial cells, macrophages, and neutrophils in vitro. Stimulation with IL-26 inhibited the inherent release of neutrophil elastase and myeloperoxidase in unexposed neutrophils. This stimulation also inhibited the expression of activity makers in neutrophils exposed to Klebsiella pneumoniae. In addition, priming of human lung tissue ex vivo with exogenous IL-26 potentiated the endotoxin-induced increase in mRNA for other cytokines involved in the innate immune response, including the master Th17-regulator IL-23 and the archetype inhibitory cytokine IL-10. Finally, neutralization of endogenous IL-26 clearly increased the growth of Klebsiella pneumoniae in the macrophage culture. These findings suggest that IL-26 is involved in bacterial lung infection in a complex manner, by modulating critical aspects of innate immune responses locally and systemically in a seemingly purposeful manner and by contributing to the killing of bacteria in a way that resembles an antimicrobial peptide. Thus, IL-26 displays both diagnostic and therapeutic potential in pneumonia and deserves to be further evaluated in these respects.

Imperatorin Alleviates Psoriasiform Dermatitis by Blocking Neutrophil Respiratory Burst, Adhesion, and Chemotaxis Through Selective Phosphodiesterase 4 Inhibition

Aim: Neutrophil infiltration and increased oxidative stress are involved in the pathogenesis and severity of psoriasis. Although the therapy of psoriasis remains elusive, targeting treatment to reduce oxidative stress is considered a potential option. Our study demonstrates the anti-inflammatory effects of a natural furocoumarin, imperatorin, on activated human neutrophils and psoriasiform dermatitis in mice. Results: Imperatorin inhibited superoxide anion generation, neutrophil adhesion, and migration in N-formyl-l-methionyl-l-leucyl-l-phenylalanine (fMLF)-stimulated human neutrophils. Further studies showed that imperatorin induced a decrease in cAMP-specific phosphodiesterase (PDE) activity, and increased intracellular cAMP levels and protein kinase A (PKA) activity in human neutrophils. The enzyme activities of PDE4 subtypes, but not PDE3 and PDE7, were inhibited by imperatorin. Furthermore, imperatorin inhibited the phosphorylation of protein kinase B (Akt), extracellular regulated kinase (ERK), and c-Jun N-terminal kinase (JNK), as well as Ca²⁺ mobilization in fMLF-stimulated neutrophils. These suppressive effects of imperatorin on cell responses and signaling were reversed by PKA inhibitor, suggesting that cAMP/PKA is involved in the anti-inflammatory effects of imperatorin. In vivo studies of imiquimod- and interleukin-23-induced mouse psoriasiform dermatitis demonstrated that imperatorin alleviated skin desquamation, epidermal thickening, keratinocyte hyperproliferation, and neutrophil infiltration. Innovation and Conclusion: Our results demonstrate that imperatorin inhibits human neutrophil respiratory burst, adhesion, and migration through the elevation of cAMP/PKA to inhibit Akt, ERK, JNK, and Ca²⁺ mobilization. Imperatorin is a natural inhibitor of PDE4A/B/C and may serve as a lead for developing new therapeutics to treat neutrophilic psoriasis. Antioxid. Redox Signal. 35, 885-903.

Extracellular Sphingomyelinase Rv0888 of Mycobacterium tuberculosis Contributes to Pathological Lung Injury of Mycobacterium smegmatis in Mice via Inducing Formation of Neutrophil Extracellular Traps

Mycobacterium tuberculosis is the causative agent of tuberculosis (TB), which mainly causes pulmonary injury and tubercles. Although macrophages are generally considered to harbor the main cells of M. tuberculosis, new evidence suggests that neutrophils are rapidly recruited to the infected lung. M. tuberculosis itself, or its early secreted antigenic target protein 6 (ESAT-6), can induce formation of neutrophil extracellular traps (NETs). However, NETs trap mycobacteria but are unable to kill them. The role of NETs’ formation in the pathogenesis of mycobacteria remains unclear. Here, we report a new M. tuberculosis extracellular factor, bifunctional enzyme Rv0888, with both nuclease and sphingomyelinase activities. Rv0888 sphingomyelinase activity can induce NETs’ formation in vitro and in the lung of the mice and enhance the colonization ability of Mycobacterium smegmatis in the lungs of mice. Mice infected by M. smegmatis harboring Rv0888 sphingomyelinase induced pathological injury and inflammation of the lung, which was mainly mediated by NETs, induced by Rv0888 sphingomyelinase, associated protein (myeloperoxidase) triggered caspase-3. In summary, the study sheds new light on the pathogenesis of mycobacteria and reveals a novel target for TB treatment.

Strain-Specific Impact of Fusobacterium nucleatum on Neutrophil Function

BACKGROUND

Neutrophil function is critical for initiation and progression of infecto-inflammatory diseases. Key quorum-sensing plaque bacteria, such as Fusobacterium nucleatum, act as bridging species between early and late colonizer pathogens, such as Porphyromonas gingivalis, as the biofilm ages and periodontal inflammation increases. This study is designed to determine impact of different F. nucleatum strains on neutrophil function.

METHODS

Cells of human promyelocytic leukemia cell line-60 were differentiated into neutrophil-like cells and cultured with F. nucleatum strains of subspecies (ssp.) nucleatum ATCC 25586, ssp. polymorphum ATCC 10953, and ssp. vincentii ATCC 49256. Neutrophil phagocytosis of F. nucleatum strains and neutrophil apoptosis were analyzed by flow cytometry. Superoxide generation was measured by cytochrome C reduction in the presence and absence of N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP) (1 μM) stimulation. Proinflammatory cytokine release was determined after 2, 6, and 24 hours of culture in the presence/absence of different F. nucleatum strains. Expression of Toll-like receptor (TLR)2, TLR4, and nuclear factor (NF)-kappa B mRNA levels were analyzed using real-time quantitative polymerase chain reaction. Each experiment was repeated at least three times in triplicate. Data were analyzed using analysis of variance followed by post hoc Bonferroni correction.

RESULTS

All strains of F. nucleatum significantly increased phagocytic capacity of neutrophils. Neutrophil phagocytosis of F. nucleatum ssp. polymorphum was significantly greater than that of F. nucleatum ssp. vincentii and ssp. nucleatum (P <0.001). F. nucleatum ssp. nucleatum and ssp. polymorphum significantly blocked fMLP-induced superoxide generation (P <0.001). Although F. nucleatum vincentii also reduced superoxide generation (25%), the impact was not as strong as that of ssp. nucleatum (83%) and ssp. polymorphum (100%). All F. nucleatum strains stimulated significant increase in neutrophil apoptosis compared with control (P <0.001) and significantly increased expression of NF-κB mRNA in neutrophils (P <0.05). Levels of interleukin-8 and tumor necrosis factor-α produced by neutrophils were significantly increased in all F. nucleatum groups compared with control (P <0.001).

CONCLUSIONS

These findings suggest that different strains of F. nucleatum impact neutrophil function in different ways. Two of three subspecies blocked neutrophil superoxide generation in response to a secondary stimulus, preventing oxidative killing by neutrophils. The direct role of bridging species in pathogenesis of periodontitis may be greater than previously suspected in which they create a favorable environment for pathogenic transition of the dental ecosystem.

Peripheral blood neutrophil cytokine hyper-reactivity in chronic periodontitis

Pro-inflammatory cytokine release (IL-8, IL-6, TNF-α, IL-1β) by peripheral blood neutrophils, isolated from periodontitis patients (before/after therapy) and matched controls, was determined after 18 h culture in the presence/absence of Escherichia coli LPS, opsonised Staphylococcus aureus, heat-killed Fusobacterium nucleatum and Porphyromonas gingivalis. All cultures demonstrated differences in the amounts of each cytokine detected (P < 0.0001), with a clear release pattern (IL-8 > IL-6 > TNF-α = IL-1β). Median cytokine release from unstimulated patient neutrophils was consistently, but non-significantly, higher than from control cells. Stimulated cytokine release from untreated patient neutrophils was also consistently higher than from control cells. This hyper-reactivity was significant for all tested cytokines when data for all stimuli were combined (P < 0.016). In terms of individual stimuli, significant hyper-reactivity was detected with LPS (IL-8), F. nucleatum (IL-8, TNF-α), opsonised S. aureus (IL-8, TNF-α, IL-1β) and P. gingivalis (IL-8, IL-1β). Cytokine production by patient neutrophils did not reduce following successful non-surgical periodontal therapy and, except for responses to F. nucleatum, the cytokine hyper-reactivity detected pre-therapy was retained. These data demonstrate that chronic periodontitis is characterised by neutrophils that constitutively exhibit cytokine hyper-reactivity, the effects of which could modulate local and systemic inflammatory-immune responses and influence the risk and severity of periodontitis-associated systemic inflammatory diseases.

Defining a pro-inflammatory neutrophil phenotype in response to schistosome eggs

Neutrophils contribute to the pathological processes of a number of inflammatory disorders, including rheumatoid arthritis, sepsis and cystic fibrosis. Neutrophils also play prominent roles in schistosomiasis japonica liver fibrosis, being central mediators of inflammation following granuloma formation. In this study, we investigated the interaction between Schistosoma japonicum eggs and neutrophils, and the effect of eggs on the inflammatory phenotype of neutrophils. Our results showed significant upregulated expression of pro-inflammatory cytokines (IL-1α, IL-1β and IL-8) and chemokines (CCL3, CCL4 and CXCL2) in neutrophils after 4 h in vitro stimulation with S. japonicum eggs. Furthermore, mitochondrial DNA was released by stimulated neutrophils, and induced the production of matrix metalloproteinase 9 (MMP-9), a protease involved in inflammation and associated tissue destruction. We also found that intact live eggs and isolated soluble egg antigen (SEA) triggered the release of neutrophil extracellular traps (NETs), but, unlike those reported in bacterial or fungal infection, NETs did not kill schistosome eggs in vitro. Together these show that S. japonicum eggs can induce the inflammatory phenotype of neutrophils, and further our understanding of the host-parasite interplay that takes place within the in vivo microenvironment of schistosome-induced granuloma. These findings represent novel findings in a metazoan parasite, and confirm characteristics of NETs that have until now, only been observed in response to protozoan pathogens.

Neutrophil dependence of vascular remodeling after Mycoplasma infection of mouse airways

Vascular remodeling is a feature of sustained inflammation in which capillaries enlarge and acquire the phenotype of venules specialized for plasma leakage and leukocyte recruitment. We sought to determine whether neutrophils are required for vascular remodeling in the respiratory tract by using Mycoplasma pulmonis infection as a model of sustained inflammation in mice. The time course of vascular remodeling coincided with the influx of neutrophils during the first few days after infection and peaked at day 5. Depletion of neutrophils with antibody RB6-8C5 or 1A8 reduced neutrophil influx and vascular remodeling after infection by about 90%. Similarly, vascular remodeling after infection was suppressed in Cxcr2(-/-) mice, in which neutrophils adhered to the endothelium of venules but did not extravasate into the tissue. Expression of the venular adhesion molecule P-selectin increased in endothelial cells from day 1 to day 3 after infection, as did expression of the Cxcr2-receptor ligands Cxcl1 and Cxcl2. Tumor necrosis factor α (TNFα) expression increased more than sixfold in the trachea of wild-type and Cxcr2(-/-) mice, but intratracheal administration of TNFα did not induce vascular remodeling similar to that seen in infection. We conclude that neutrophil influx is required for remodeling of capillaries into venules in the airways of mice with Mycoplasma infection and that TNFα signaling is necessary but not sufficient for vascular remodeling.

Regulatory T-cell vaccination independent of auto-antigen

To date, efforts to treat autoimmune diseases have primarily focused on the disease symptoms rather than on the cause of the disease. In large part, this is attributed to not knowing the responsible auto-antigens (auto-Ags) for driving the self-reactivity coupled with the poor success of treating autoimmune diseases using oral tolerance methods. Nonetheless, if tolerogenic approaches or methods that stimulate regulatory T (T_reg) cells can be devised, these could subdue autoimmune diseases. To forward such efforts, our approach with colonization factor antigen I (CFA/I) fimbriae is to establish bystander immunity to ultimately drive the development of auto-Ag-specific T_reg cells. Using an attenuated Salmonella vaccine expressing CFA/I fimbriae, fimbriae-specific T_reg cells were induced without compromising the vaccine's capacity to protect against travelers' diarrhea or salmonellosis. By adapting the vaccine's anti-inflammatory properties, it was found that it could also dampen experimental inflammatory diseases resembling multiple sclerosis (MS) and rheumatoid arthritis. Because of this bystander effect, disease-specific T_reg cells are eventually induced to resolve disease. Interestingly, this same vaccine could elicit the required T_reg cell subset for each disease. For MS-like disease, conventional CD25⁺ T_reg cells are stimulated, but for arthritis CD39⁺ T_reg cells are induced instead. This review article will examine the potential of treating autoimmune diseases without having previous knowledge of the auto-Ag using an innocuous antigen to stimulate T_reg cells via the production of transforming growth factor-β and interleukin-10.

Novel insight into neutrophil immune responses by dry mass determination of Candida albicans morphotypes

The common fungal pathogen Candida albicans has the ability to grow as a yeast or as a hypha and can alternate between these morphotypes. The overall biomass of both morphotypes increases with growth. However, only yeasts, but not hyphae, exist as discrete cellular entities. Multiplicity of infection (MOI) is a useful parameter to determine the initial inoculum of yeasts for in vitro infection assays. Since the amount of hyphae is difficult to quantify, comparable starting conditions in such assays cannot be determined accurately for yeasts and hyphae using MOI. To circumvent this problem, we have established a set of correlation coefficients to convert fungal metabolic activity and optical density to dry mass. Using these correlations, we were able to accurately compare ROS production and IL-8 release by polymorphonuclear neutrophils upon infection with equal dry mass amounts of yeast and hyphal morphotypes. Neutrophil responses depended on the initial form of infection, irrespective of C. albicans wild-type yeasts transforming to hyphal growth during the assay. Infection with a high mass of live C. albicans yeasts resulted in lower neutrophil ROS and this decrease stems from efficient ROS detoxification by C. albicans without directly affecting the phagocyte ROS machinery. Moreover, we show that dead C. albicans induces significantly less ROS and IL-8 release than live fungi, but thimerosal-killed C. albicans were still able to detoxify neutrophil ROS. Thus, the dry mass approach presented in this study reveals neutrophil responses to different amounts and morphotypes of C. albicans and serves as a template for studies that aim to identify morphotype-specific responses in a variety of immune cells.

Inhibition of pre-B cell colony-enhancing factor (PBEF/NAMPT/visfatin) decreases the ability of human neutrophils to generate reactive oxidants but does not impair bacterial killing

NAMPT, also known as PBEF and visfatin, can act extracellularly as a cytokine-like molecule or intracellularly as a NAMPT, regulating NAD biosynthesis in the NAD salvage pathway. Inhibitors of NAMPT have anti-inflammatory and anticancer activity and are finding use as therapeutic agents. In view of the importance of NAD metabolism in neutrophil function, we determined the effects of NAMPT inhibition on a variety of neutrophil functions associated with their role in host protection against infections. Incubation of human neutrophils with the NAMPT inhibitor APO866 decreased neutrophil NAD(P)/H levels in a dose- and time-dependent manner but without a concomitant change in cell viability. NAMPT inhibition did not affect the expression of a number of cell-surface receptors involved in adhesion and opsono-phagocytosis, but the respiratory burst was decreased significantly. Whereas opsono-phagocytosis of Staphylococcus aureus was unaffected by NAMPT inhibition, intraphagosomal oxidant production was decreased. However, the killing efficiency of neutrophils was unaffected. These data indicate that therapeutic NAMPT inhibition is unlikely to have deleterious effects on host protection against infections, in spite of this ability to down-regulate neutrophil respiratory burst activity significantly.

NET balancing: a problem in inflammatory lung diseases

Neutrophil extracellular traps (NETs) are beneficial antimicrobial defense structures that can help fight against invading pathogens in the host. However, recent studies reveal that NETs exert adverse effects in a number of diseases including those of the lung. Many inflammatory lung diseases are characterized with a massive influx of neutrophils into the airways. Neutrophils contribute to the pathology of these diseases. To date, NETs have been identified in the lungs of cystic fibrosis (CF), acute lung injury (ALI), allergic asthma, and lungs infected with bacteria, virus, or fungi. These microbes and several host factors can stimulate NET formation, or NETosis. Different forms of NETosis have been identified and are dependent on varying types of stimuli. All of these pathways however appear to result in the formation of NETs that contain DNA, modified extracellular histones, proteases, and cytotoxic enzymes. Some of the NET components are immunogenic and damaging to host tissue. Innate immune collectins, such as pulmonary surfactant protein D (SP-D), bind NETs, and enhance the clearance of dying cells and DNA by alveolar macrophages. In many inflammatory lung diseases, bronchoalveolar SP-D levels are altered and its deficiency results in the accumulation of DNA in the lungs. Some of the other therapeutic molecules under consideration for treating NET-related diseases include DNases, antiproteases, myeloperoxidase (MPO) inhibitors, peptidylarginine deiminase-4 inhibitors, and anti-histone antibodies. NETs could provide important biological advantage for the host to fight against certain microbial infections. However, too much of a good thing can be a bad thing. Maintaining the right balance of NET formation and reducing the amount of NETs that accumulate in tissues are essential for harnessing the power of NETs with minimal damage to the hosts.

Granulocytes in helminth infection -- who is calling the shots?

Helminths are parasitic organisms that can be broadly described as “worms” due to their elongated body plan, but which otherwise differ in shape, development, migratory routes and the predilection site of the adults and larvae. They are divided into three major groups: trematodes (flukes), which are leaf-shaped, hermaphroditic (except for blood flukes) flatworms with oral and ventral suckers; cestodes (tapeworms), which are segmented, hermaphroditic flatworms that inhabit the intestinal lumen; and nematodes (roundworms), which are dioecious, cylindrical parasites that inhabit intestinal and peripheral tissue sites. Helminths exhibit a sublime co-evolution with the host´s immune system that has enabled them to successfully colonize almost all multicellular species present in every geographical environment, including over two billion humans. In the face of this challenge, the host immune system has evolved to strike a delicate balance between attempts to neutralize the infectious assault versus limitation of damage to host tissues. Among the most important cell types during helminthic invasion are granulocytes: eosinophils, neutrophils and basophils. Depending on the specific context, these leukocytes may have pivotal roles in host protection, immunopathology, or facilitation of helminth establishment. This review provides an overview of the function of granulocytes in helminthic infections.

Dexamethasone and betamethasone protect against lipopolysaccharide-induced brain damage in neonatal rats

INTRODUCTION

The aim of this study was to test whether dexamethasone (Dex) and betamethasone (Beta), two of the most commonly used corticosteroids, protect against lipopolysaccharide (LPS)-induced white matter damage and neurobehavioral dysfunction.

METHODS

LPS or sterile saline was injected into the brain white matter of rat pups at postnatal day 5 (P5), and Dex or Beta was given intraperitoneally to the rat pups 1 h before the LPS microinjection. Brain inflammatory response, brain damage, and myelination were examined at P6, P8, and P14. Neurobehavioral tests were performed from P3 through P22.

RESULTS

Our results demonstrate that Dex and Beta markedly diminish the LPS-induced brain inflammatory response, restore myelin basic protein (MBP) expression, and alleviate lateral ventricle dilation. Both corticosteroids demonstrate significant protection against most LPS-induced behavioral deficits, including those in rearing, vibrissa-elicited forelimb-placing, beam walking, learning, and elevated plus-maze test. Of note, only Beta improved the locomotion and stereotype dysfunction. In contrast to their beneficial effects, neither drug prevented LPS-induced delay in body weight gain from P6 through P21.

DISCUSSION

Our study suggests that if their adverse effects are minimized, corticosteroids may be the potential candidate drugs to prevent brain damage in premature infants.

Age-related comparisons of evolution of the inflammatory response after intracerebral hemorrhage in rats

In the hours to days after intracerebral hemorrhage (ICH), there is an inflammatory response within the brain characterized by the infiltration of peripheral neutrophils and macrophages and the activation of brain-resident microglia and astrocytes. Despite the strong correlation of aging and ICH incidence, and increasing information about cellular responses, little is known about the temporal- and age-related molecular responses of the brain after ICH. Here, we monitored a panel of 27 genes at 6 h and 1, 3, and 7 days after ICH was induced by injecting collagenase into the striatum of young adult and aged rats. Several molecules (CR3, TLR2, TLR4, IL-1β, TNFα, iNOS, IL-6) were selected to reflect the classical activation of innate immune cells (macrophages, microglia) and the potential to exacerbate inflammation and damage brain cells. Most of the others are associated with the resolution of innate inflammation, alternative pathways of macrophage/microglial activation, and the repair phase after acute injury (TGFβ, IL-1ra, IL-1r2, IL-4, IL-13, IL-4Rα, IL-13Rα1, IL-13Rα2, MRC1, ARG1, CD163, CCL22). In young animals, the up-regulation of 26 in 27 genes (not IL-4) was detected within the first week. Differences in timing or levels between young and aged animals were detected for 18 of 27 genes examined (TLR2, GFAP, IL-1β, IL-1ra, IL-1r2, iNOS, IL-6, TGFβ, MMP9, MMP12, IL-13, IL-4Rα, IL-13Rα1, IL-13Rα2, MRC1, ARG1, CD163, CCL22), with a generally less pronounced or delayed inflammatory response in the aged animals. Importantly, within this complex response to experimental ICH, the induction of pro-inflammatory, potentially harmful mediators often coincided with resolving and beneficial molecules.

Exploiting the interplay between innate and adaptive immunity to improve immunotherapeutic strategies for Epstein-Barr-virus-driven disorders

The recent demonstration that immunotherapeutic approaches may be clinically effective for cancer patients has renewed the interest for this strategy of intervention. In particular, clinical trials using adoptive T-cell therapies disclosed encouraging results, particularly in the context of Epstein-Barr-virus- (EBV-) related tumors. Nevertheless, the rate of complete clinical responses is still limited, thus stimulating the development of more effective therapeutic protocols. Considering the relevance of innate immunity in controlling both infections and cancers, innovative immunotherapeutic approaches should take into account also this compartment to improve clinical efficacy. Evidence accumulated so far indicates that innate immunity effectors, particularly NK cells, can be exploited with therapeutic purposes and new targets have been recently identified. We herein review the complex interactions between EBV and innate immunity and summarize the therapeutic strategies involving both adaptive and innate immune system, in the light of a fruitful integration between these immunotherapeutic modalities for a better control of EBV-driven tumors.

Clinical microfluidics for neutrophil genomics and proteomics

Neutrophils play critical roles in modulating the immune response. We present a robust methodology for rapidly isolating neutrophils directly from whole blood and develop ‘on-chip’ processing for mRNA and protein isolation for genomics and proteomics. We validate this device with an ex vivo stimulation experiment and by comparison with standard bulk isolation methodologies. Lastly, we implement this tool as part of a near patient blood processing system within a multi-center clinical study of the immune response to severe trauma and burn injury. The preliminary results from a small cohort of patients in our study and healthy controls show a unique time-dependent gene expression pattern clearly demonstrating the ability of this tool to discriminate temporal transcriptional events of neutrophils within a clinical setting.

IL-8 decreases HIV-1 transcription in peripheral blood lymphocytes and ectocervical tissue explants

IL-8 is enhanced in the peripheral blood and lymphoid tissue of HIV-infected individuals, suggesting that IL-8 is important in the pathogenesis of HIV-1 infection and progression to AIDS. Characterizing the mechanisms of IL-8 regulation of HIV-1 replication may be relevant in addressing the role of IL-8 as a therapeutic target in HIV-1 infection. We evaluated replication of primary R5-tropic HIV-1 in peripheral blood lymphocytes and ectocervical tissue explants infected in vitro in the presence of physiological concentrations of IL-8 found in the serum and genital tract secretions of HIV-infected individuals. To identify the specific stages of the viral life cycle targeted by IL-8, we performed real-time polymerase chain reaction to detect HIV-1 reverse transcription, integration, and transcription. Early during the infection, IL-8 decreased HIV-1 reverse transcription and viral integration. This effect was transient, as on day 4 after infection, we detected no differences on HIV-1 DNA or proviral DNA in peripheral blood lymphocyte. IL-8 decreased HIV-1 transcription in both lymphocytes and ectocervical tissue explants. The decrease in viral RNA expression was associated with reduced HIV-1 replication, as measured by viral p24 release in the culture supernatants. This is the first report to suggest that IL-8 decreases replication of primary R5-tropic HIV-1 by transcriptional mechanisms.

Chemokine-mediated rapid turnover of myeloid-derived suppressor cells in tumor-bearing mice

Tumor growth is associated with aberrant myelopoiesis, including the accumulation of CD11b(+)Gr-1(+) myeloid-derived suppressor cells (MDSCs) that have the potential to promote tumor growth. However, the identity, growth, and migration of tumor-associated MDSCs remain undefined. We demonstrate herein that MDSCs at tumor site were composed primarily of bone marrow-derived CD11b(+)Gr-1(hi)Ly-6C(int) neutrophils and CD11b(+)Gr-1(int/dull)Ly-6C(hi) macrophages. Unexpectedly, in vivo bromodeoxyuridine (BrdU) labeling and parabiosis experiments revealed that tumor-infiltrating macrophages were replenished more rapidly than neutrophils. CCR2 deficiency caused striking conversion of infiltrating cellular dominance from macrophages to neutrophils in the tumor with the excessive production of CXCR2 ligands and granulocyte-colony stimulating factor in the tumor without affecting tumor growth. Overall, our data established the identity and dynamics of MDSCs in a tumor-bearing host mediated by chemokines and elucidated unexpected effects of the paucity of macrophages on tumor development.

Exacerbation of antigen-induced arthritis in IFN-gamma-deficient mice as a result of unrestricted IL-17 response

Proinflammatory Th1 responses are believed to be involved in the induction and perpetuation of rheumatoid arthritis. However, the role of IFN-gamma, the major cytokine produced by Th1 cells, is still incompletely defined. In the present study, we investigated the effects of IFN-gamma deficiency (IFN-gamma(-/-)) on the course of experimental murine Ag-induced arthritis (AIA). In the acute stage of disease, IFN-gamma(-/-) AIA mice showed significantly increased inflammatory responses compared with wild-type C57BL/6 AIA mice, i.e., exacerbated joint swelling, increased delayed-type hypersensitivity reaction, and increased histopathological scores of arthritis. Intraarticular administration of exogenous IFN-gamma at induction of AIA significantly suppressed these acute aggravation effects. Stimulated cells isolated from lymph nodes and spleen of IFN-gamma(-/-) AIA mice showed increased production of IL-2, IL-4, IL-5, IL-6, but most prominently of IL-17. These elevations were paralleled by decreased humoral immune responses, with low serum levels of total and Ag-specific IgG (IgG1, IgG2a(b), IgG2b, IgG3). At immunohistology, the knee joints of IFN-gamma(-/-) AIA mice showed massive neutrophil granulocyte infiltration. Treatment with mAbs neutralizing IL-17 diminished the acute inflammation. In vitro, Th cell expansion and production of IL-17 upon restimulation were effectively and dose dependently inhibited by IFN-gamma. These results clearly demonstrate that IFN-gamma has anti-inflammatory properties during the initial phase of AIA, and indicate that IFN-gamma deficiency exerts disease-promoting effects, preferentially via IL-17-modulated pathways.

NFkappaB is persistently activated in continuously stimulated human neutrophils

Increased activation of the transcription factor NFkappaB in the neutrophils has been associated with the pathogenesis of sepsis, acute lung injury (ALI), bronchopulmonary dysplasia (BPD), and other neutrophil-mediated inflammatory disorders. Despite recent progress in analyzing early NFkappaB activation in human neutrophils, activation of NFkappaB in persistently stimulated neutrophils has not been previously studied. Because it is the persistent NFkappaB activation that is thought to be involved in the host response to sepsis and the pathogenesis of ALI and BPD, we hypothesized that continuously stimulated human neutrophils may exhibit a late phase of NFkappaB activity. The goal of this study was to analyze the NFkappaB activation and expression of IkappaB and NFkappaB proteins during neutrophil stimulation with inflammatory signals for prolonged times. We demonstrate that neutrophil stimulation with lipopolysaccharide (LPS) and tumor necrosis factor-alpha (TNFalpha) induces, in addition to the early activation at 30-60 min, a previously unrecognized late phase of NFkappaB activation. In LPS-stimulated neutrophils, this NFkappaB activity typically had a biphasic character, whereas TNFalpha-stimulated neutrophils exhibited a continuous NFkappaB activity peaking around 9 h after stimulation. In contrast to the early NFkappaB activation that inversely correlates to the nuclear levels of IkappaBalpha, however, in continuously stimulated neutrophils, NFkappaB is persistently activated despite considerable levels of IkappaBalpha present in the nucleus. Our data suggest that NFkappaB is persistently activated in human neutrophils during neutrophil-mediated inflammatory disorders, and this persistent NFkappaB activity may represent one of the underlying mechanisms for the continuous production of proinflammatory mediators.

Effects of Menstrual Cycle Status and Gender on Human Neutrophil Phenotype

PROBLEM

The effects of gender and fluctuating ovarian hormones on neutrophil phenotype have yet to be characterized.

METHOD OF STUDY

Neutrophils from females at days 7, 14, 21, and 28 of the menstrual cycle were analyzed by flow cytometry for surface receptor, granule protein, and intracellular cytokine expression. Comparisons were made to neutrophils from males isolated at 7-day intervals during 1 month.

RESULTS

Decreased MMP-9 and TNF-alpha expression by neutrophils from females was observed during the periovulatory period. Comparing the genders, cells from females during the periovulatory period expressed less CD11b and CD18 than those from males. CXCR1 surface levels were higher on neutrophils from female donors.

CONCLUSIONS

Neutrophil phenotype varies minimally during the menstrual cycle and between the genders. Our data provide support for a potential anti-inflammatory effect of ovarian hormones on neutrophils.

NFkappaB is persistently activated in continuously stimulated human neutrophils

Increased activation of the transcription factor NFkappaB in the neutrophils has been associated with the pathogenesis of sepsis, acute lung injury (ALI), bronchopulmonary dysplasia (BPD), and other neutrophil-mediated inflammatory disorders. Despite recent progress in analyzing early NFkappaB activation in human neutrophils, activation of NFkappaB in persistently stimulated neutrophils has not been previously studied. Because it is the persistent NFkappaB activation that is thought to be involved in the host response to sepsis and the pathogenesis of ALI and BPD, we hypothesized that continuously stimulated human neutrophils may exhibit a late phase of NFkappaB activity. The goal of this study was to analyze the NFkappaB activation and expression of IkappaB and NFkappaB proteins during neutrophil stimulation with inflammatory signals for prolonged times. We demonstrate that neutrophil stimulation with lipopolysaccharide (LPS) and tumor necrosis factor-alpha (TNFalpha) induces, in addition to the early activation at 30-60 min, a previously unrecognized late phase of NFkappaB activation. In LPS-stimulated neutrophils, this NFkappaB activity typically had a biphasic character, whereas TNFalpha-stimulated neutrophils exhibited a continuous NFkappaB activity peaking around 9 h after stimulation. In contrast to the early NFkappaB activation that inversely correlates to the nuclear levels of IkappaBalpha, however, in continuously stimulated neutrophils, NFkappaB is persistently activated despite considerable levels of IkappaBalpha present in the nucleus. Our data suggest that NFkappaB is persistently activated in human neutrophils during neutrophil-mediated inflammatory disorders, and this persistent NFkappaB activity may represent one of the underlying mechanisms for the continuous production of proinflammatory mediators.

The humoral pattern recognition receptor PTX3 is stored in neutrophil granules and localizes in extracellular traps

The long pentraxin (PTX) 3 is produced by macrophages and myeloid dendritic cells in response to Toll-like receptor agonists and represents a nonredundant component of humoral innate immunity against selected pathogens. We report that, unexpectedly, PTX3 is stored in specific granules and undergoes release in response to microbial recognition and inflammatory signals. Released PTX3 can partially localize in neutrophil extracellular traps formed by extruded DNA. Eosinophils and basophils do not contain preformed PTX3. PTX3-deficient neutrophils have defective microbial recognition and phagocytosis, and PTX3 is nonredundant for neutrophil-mediated resistance against Aspergillus fumigatus. Thus, neutrophils serve as a reservoir, ready for rapid release, of the long PTX3, a key component of humoral innate immunity with opsonic activity.

Chronic renal failure-induced multiple-organ injury in rats is alleviated by the selective CysLT1 receptor antagonist montelukast

Chronic renal failure (CRF) is associated with oxidative stress that promotes production of reactive oxygen species and cytokine release. We aimed to investigate the possible protective effect of montelukast, a CysLT1 receptor antagonist, against oxidative damage in a rat model of CRF, induced by 5/6 reduction of renal mass. Male Wistar albino rats were randomly assigned to either the CRF group or the sham-operated control group, which received saline or montelukast (10mg/kg, i.p.) for 4 weeks. At the end of the 4 weeks, rats were decapitated and trunk blood was collected. Creatinine, blood urea nitrogen and lactate dehydrogenase (LDH) activity were measured in the serum samples, while leukotriene B(4), TNF-alpha, IL-1 beta, IL-6, total antioxidant capacity (AOC) and leukocyte apoptosis were assayed in plasma samples. Kidney, lung, heart and brain tissue samples were taken for the determination of tissue malondialdehyde (MDA), glutathione (GSH) levels, and myeloperoxidase (MPO) activity. Oxidant-induced tissue fibrosis was determined by tissue collagen contents, and the extent of tissue injuries was analyzed microscopically. CRF caused significant decreases in tissue GSH and plasma AOC, which were accompanied with significant increases in MDA levels, MPO activities, and collagen contents of all the studied tissues, while the circulating levels of the pro-inflammatory mediators, LDH activity, creatinine and BUN were elevated. Montelukast treatment reversed all these biochemical indices, as well as histopathological alterations induced by CRF. Similarly, flow cytometric measurements revealed that leukocyte apoptosis was increased in CRF group, while montelukast reversed this effect. In conclusion, CRF-induced oxidative tissue injury occurs via the activation of pro-inflammatory mediators and by neutrophil infiltration into tissues, and that protective effects of montelukast on CRF-induced injury can be attributed to its ability to inhibit neutrophil infiltration and apoptosis, to balance oxidant-antioxidant status and to regulate the generation of pro-inflammatory mediators.

Interleukin-4 regulates proteoglycan-induced arthritis by specifically suppressing the innate immune response

OBJECTIVE

Interleukin-4 (IL-4) is an antiinflammatory cytokine that inhibits the onset and severity of proteoglycan-induced arthritis (PGIA). To distinguish the role of IL-4 in the innate immune response versus the adaptive immune response, we generated mice with a specific deletion of the IL-4 receptor alpha-chain (IL-4Ralpha) in macrophages and neutrophils.

METHODS

To obtain mice in which IL-4Ralpha is deleted in macrophages and neutrophils, we intercrossed mice carrying a loxP-flanked (floxed) IL-4Ralpha allele and Cre recombinase expressed under control of the regulatory region for the lysozyme M gene (LysM(cre) mice) with conditional IL-4Ralpha(flox/flox) mice and then mated them to complete IL-4Ralpha(-/-) mice to obtain hemizygous LysM(cre)IL-4Ralpha(flox/-) mice. LysM(cre)-negative IL-4Ralpha(flox/-) mice (IL-4Ralpha(flox/-) mice) were used as control mice. PGIA was induced by immunization with human PG in adjuvant. The onset, incidence, and severity of arthritis were monitored over time. Levels of proinflammatory cytokines were measured in the sera of PG-immunized mice, and cytokine and chemokine transcripts were measured in joints.

RESULTS

The severity of PGIA was exacerbated in IL-4Ralpha(-/-) and LysM(cre)IL-4Ralpha(flox/-) mice in comparison with control (IL-4Ralpha(flox/-)) mice. The increase in arthritis susceptibility in IL-4Ralpha(-/-) and LysM(cre)IL-4Ralpha(flox/-) mice correlated with elevated serum levels of the proinflammatory cytokines IL-1beta and IL-6 and with elevated cytokine (IL-1beta and IL-6) and chemokine (macrophage inflammatory protein 1alpha [MIP-1alpha] and MIP-2) transcripts from joints. However, arthritis susceptibility did not correlate with IL-2 or interferon-gamma (IFNgamma) concentrations or with PG-specific antibody IgG2a isotype, since levels of IL-2, IFNgamma, or PG-specific antibody IgG2a isotype in control (IL-4Ralpha(flox/-)) and LysM(cre)IL-4Ralpha(flox/-) mice were reduced in comparison with those in IL-4Ralpha(-/-) mice.

CONCLUSION

These findings indicate that IL-4 functions as a major antiinflammatory cytokine in PGIA by governing the activity of macrophages/neutrophils and less so by controlling T cell activity and autoantibody isotype expression.

Shedding of sCD14 by bovine neutrophils following activation with bacterial lipopolysaccharide results in down-regulation of IL-8

CD14, the leukocyte co-receptor for lipopolysaccharide (LPS), is important in the response of bovine polymorphonuclear neutrophil leukocytes (PMN) to Gram-negative bacteria. In other species, the expression of CD14 on the surface of PMN was shown to increase after exposure to inflammatory stimuli. These newly expressed molecules may originate from either an intracellular pool or through new gene expression. We sought to characterize bovine PMN cell surface expression and shedding of CD14 molecules, and CD14's effect on secretion of the chemoattractants IL-8 and IL-1beta by PMN. Bovine PMN were incubated in RPMI for 20 h at 37 degrees C with LPS (1, 10, 100 microg/mL). IL-8 release increased with treatment of 1 microg/mL LPS, but decreased 41.5 and 95% at the 10 and 100 microg/mL concentrations of LPS, respectively. In contrast, shedding of CD14 from the surface of PMN only increased at the highest concentration of LPS (100 microg/mL). Secretion of IL-1beta was similar regardless of the LPS concentration used to stimulate PMN. The effect of PMN concentration (1 x 10(7), 2.5 x 10(7), 5 x 10(7), and 10 x 10(7)/mL) on CD14 cell surface expression and shedding of IL-8 and IL-1beta were also determined. Shedding of CD14 by PMN increased with increasing concentration of PMN after exposure to 0.1 and 10 microg/mL of LPS, while secretion of IL-8 decreased. IL-1beta increased at the highest concentration of PMN. The use of real time polymerase chain reaction showed that CD14 mRNA expression was not different between control and LPS-stimulated cells, indicating that the sCD14 came from either membrane bound CD14 or a preformed pool. Our results demonstrate that release of CD14 from PMN suppresses secretion of IL-8, and may be an important regulatory mechanism for controlling excessive migration of PMN into the bovine mammary gland.

Human Fallopian Tube Neutrophils – A Distinct Phenotype from Blood Neutrophils

PROBLEM

The role of neutrophils in the human Fallopian tube (FT) is unknown. In order to provide insights into their functions in the FT, we systematically compared neutrophils from normal FT and peripheral blood (PB).

METHOD OF STUDY

Flow cytometric analysis of surface receptors, granule proteins, and intracellular cytokines expressed by neutrophils from enzymatically dispersed FT and PB was performed.

RESULTS

Fallopian tube neutrophils expressed significantly higher levels of CD64, human class II histocompatibility antigen DR (HLA-DR), gamma-interferon, and vascular endothelial growth factor than those from PB. Fewer FT neutrophils expressed IL-8 receptors compared to PB, while more expressed the receptor for the bacterial-derived chemoattractant formyl-Met-Leu-Phe (fMLP). The number of FT neutrophils containing the granule proteins matrix metalloproteinase-9, lactoferrin, and myeloperoxidase was decreased versus PB.

CONCLUSION

Fallopian tube neutrophils exhibit a phenotype distinct from PB neutrophils, suggesting functional activation of innate immune defense in the female reproductive tract as well as a potential role in maintaining normal FT physiology.

[Primary immune deficiencies in neutrophil functioning]

Neutrophils are polynuclear cells essential to innate immunity. They are the first cells to migrate from the blood to the inflammatory site where they kill pathogens and secrete various mediators that regulate innate and adaptive immunity. Functional steps required for their microbicidal activity include: transendothelial migration, migration towards the invading pathogens, and then recognition, adhesion, engulfment, and killing of the target. Primary deficiencies of these stages are expressed by repeated and/or severe bacterial and fungal infections. These deficiencies include granule abnormalities and leukocyte adhesion deficiencies Type I and II, defective pathogen recognition and the defective oxidative burst that characterizes chronic granulomatous disease.

Lipoteichoic acid (LTA) from Staphylococcus aureus stimulates human neutrophil cytokine release by a CD14-dependent, Toll-like-receptor-independent mechanism: Autocrine role of tumor necrosis factor-α in mediating LTA-induced interleukin-8 generation

OBJECTIVE

In sepsis, Gram-positive and Gram-negative bacteria provoke similar inflammatory processes. Whereas lipopolysaccharides (LPSs) are acknowledged as the principal immunostimulatory components of Gram-negative bacteria, the effect of the Gram-positive cell wall component lipoteichoic acid (LTA) is less well characterized. In the present study, we investigated the effect of highly purified LTA from Staphylococcus aureus on cytokine generation by isolated human neutrophils.

SUBJECTS

Isolated human neutrophils from healthy volunteers.

INTERVENTIONS

Incubation of neutrophils with purified LTA from S. aureus in the absence or presence of interleukin (IL)-10, anti-CD14, or anti-Toll-like-receptor antibodies.

MEASUREMENTS

Measurement of tumor necrosis factor (TNF)-alpha, IL-1beta, and IL-8 by enzyme-linked immunosorbent assay. Analysis of IL-8 mRNA by reverse transcriptase polymerase chain reaction.

CONCLUSIONS

The LTA challenge provoked a dramatic release of cytokines, with an early appearance of TNF-alpha and IL-1beta and a delayed liberation of IL-8. The first phase of IL-8 production was induced directly by LTA, whereas the second phase was endogenously mediated by TNF-alpha, as it was largely abrogated by neutralizing anti-TNF-alpha antibodies. In contrast, IL1-beta was not involved in LTA-induced IL-8 generation. Interestingly, the late phase of IL-8 generation could also be attenuated by exogenous IL-10, probably as a consequence of its downregulatory effects on TNF-alpha generation. When investigating the mechanism of LTA-induced cellular activation, activity-neutralizing antibodies demonstrated that CD14 was involved in LTA-mediated neutrophil cytokine generation. Using antibodies that neutralize the activity of Toll-like receptor 2 (TLR2) or 4 (TLR4), we also show that CD14-dependent, LTA-induced neutrophil activation did not proceed via TLR2- or TLR4-mediated pathways. In conclusion, LTA is a potent activator of human neutrophil cytokine generation, with the synthesis of the chemokine IL-8 being largely dependent on TNF-alpha generation in an autocrine fashion. This LTA-induced effect was inhibited by IL-10, dependent on CD14, and independent of TLR 2 or 4.

Breast cancer cells stimulate neutrophils to produce oncostatin M: potential implications for tumor progression

Tumor-associated and tumor-infiltrating neutrophils (TAN) and macrophages (TAM) can account for as much as 50% of the total tumor mass in invasive breast carcinomas. It is thought that tumors secrete factors that elicit a wound-repair response from TAMs and TANs and that this response inadvertently stimulates tumor progression. Oncostatin M is a pleiotropic cytokine belonging to the interleukin-6 family that is expressed by several cell types including activated human T lymphocytes, macrophages, and neutrophils. Whereas oncostatin M can inhibit the proliferation of breast cancer cells in vitro, recent studies suggest that oncostatin M may promote tumor progression by enhancing angiogenesis and metastasis. In addition, neutrophils can be stimulated to synthesize and rapidly release large quantities of oncostatin M. In this article, we show that human neutrophils secrete oncostatin M when cocultured with MDA-MB-231 and T47D human breast cancer cells. Neutrophils isolated from whole blood or breast cancer cells alone express little oncostatin M by immunocytochemistry and ELISA, but neutrophils express and release high levels of oncostatin M when they are cocultured with breast cancer cells. In addition, we show that granulocyte-macrophage colony-stimulating factor produced by breast cancer cells and cell-cell contact are both necessary for the release of oncostatin M from neutrophils. Importantly, neutrophil-derived oncostatin M induces vascular endothelial growth factor from breast cancer cells in coculture and increases breast cancer cell detachment and invasive capacity, suggesting that neutrophils and oncostatin M may promote tumor progression in vivo.

Enhancement of innate and cell-mediated immunity by antimycobacterial antibodies

We investigated the ability of human antibodies induced by Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccination to protect against mycobacterial infections. Serum samples containing mycobacterium-specific antibodies were obtained from volunteers who had received two intradermal BCG vaccinations 6 months apart. Significant increases in lipoarabinomannan (LAM)-specific immunoglobulin G (IgG) were detected after both the primary and booster vaccinations. Effects of mycobacterium-specific antibodies on surface binding and internalization of BCG by neutrophils and monocytes/macrophages were studied, using green fluorescent protein (gfp)-expressing BCG. Surface-bound gfp-expressing BCG were distinguished from intracellular BCG by surface labeling with LAM-specific monoclonal antibody. Internalization of BCG by phagocytic cells was shown to be significantly enhanced in postvaccination serum samples. Furthermore, the inhibitory effects of neutrophils and monocytes/macrophages on mycobacterial growth were significantly enhanced by BCG-induced antibodies. The growth-inhibiting effects of postvaccination sera were reversed by preabsorption of IgG with Protein G. Finally, the helper effects of antimycobacterial antibodies for the induction of cell-mediated immune responses were investigated. BCG-induced antibodies significantly enhanced proliferation and gamma interferon production in mycobacterium-specific CD4(+) and CD8(+) T cells, as well as the proportion of proliferating and degranulating CD8(+) T cells. We conclude that mycobacterium-specific antibodies are capable of enhancing both innate and cell-mediated immune responses to mycobacteria.

Acute and chronic influence of hemodialysis according to the membrane used on phagocytic function of neutrophils and monocytes and pro-inflammatory cytokines production in chronic renal failure patients

This work evaluated the phagocytic capacity of monocytes and neutrophils, and tumor necrosis factor-alpha, interleukin 6, 1 and 8 serum levels in chronic renal failure patients under peritoneal dialysis and hemodialysis treatment, compared with chronic renal failure patients without dialysis treatment and healthy individuals, in order to contribute to a better understanding of the action of these therapies on the evolution of chronic renal failure patients. All patients with chronic renal failure (under dialysis or not) showed decreased phagocytic capacity of neutrophils and monocytes. All those in hemodialysis (cellulose acetate or polysulfone membranes) showed a decreased phagocytic capacity. The phagocytic index for neutrophil was 13 times lower than that of the control group for both membranes, whereas for monocytes, only those using polysulfone membrane showed a significant decrease of 4.9 times in phagocytic capacity. There was an acute stimulation of the phagocytosis by neutrophils after a single session of dialysis with both types of membrane, while only cellulose acetate membrane decreased the phagocytic index of monocytes after the hemodialysis session. Patients using cellulose acetate showed a chronic increase in tumor necrosis factor-alpha serum levels, while those using polysulfone showed a chronic increase in interleukin 6. After a single hemodialysis procedure, no acute effect of the treatment on tumor necrosis factor-alpha and interleukin 6 levels was identified. The decreased phagocytic function of neutrophils and monocytes may account for the high levels of susceptibility of chronic renal failure patients to infections with pyogenic bacteria and tuberculosis. Furthermore, inflammatory activity may occur with both types of membrane studied, suggesting that it will be useful for these patients to evaluate some anti-inflammatory or anti-cytokine therapies against tumor necrosis factor-alpha and interleukin 6, in order to avoid cardiovascular complication.

Differing phagocytic function of monocytes and neutrophils in Chagas' cardiopathy according to the presence or absence of congestive heart failure

We evaluated the in vitro phagocytic function and the production of microbicidal oxygen radicals by monocytes and neutrophils of 9 Chagas' heart disease subjects with heart failure and 9 without the syndrome in comparison with 11 healthy subjects, by assessing phagocytosis of Saccharomyces cerevisiae and NBT reduction by peripheral blood phagocytes. Phagocytic index of monocytes of chagasics without heart failure was significantly 6.7 and 10.6 times lower than those of controls and chagasics with the congestive syndrome, respectively, due to a lesser engagement in phagocytosis and to an inability of these cells to ingest particles. Neutrophils also show in chagasics without heart failure PI 11.2 and 19.8 times lower than that of controls and chagasics with heart failure, respectively. The percent of NBT reduction was normal and similar for the three groups. Balanced opposite effects of cardiovascular and immune disturbances may be acting in Chagas' disease subjects with heart failure paradoxically recovering the altered phagocytic function.

Secretion of oncostatin M by neutrophils in rheumatoid arthritis

OBJECTIVE

Neutrophils are known to express and release a large number of proinflammatory cytokines when they are stimulated by inflammatory stimuli. The objective of this study was to determine whether neutrophils express oncostatin M (OSM), a member of the interleukin-6 family of cytokines that has been implicated in the pathogenesis of inflammatory joint disease.

METHODS

Neutrophils were isolated from the blood of healthy volunteer donors and from the blood and synovial fluid of patients with rheumatoid arthritis (RA). OSM levels were measured in cell extracts and in culture supernatants by Western blotting. Total RNA was isolated from control and granulocyte-macrophage colony-stimulating factor (GM-CSF)-treated neutrophils, and OSM messenger RNA levels were quantified by hybridization of a radiolabeled probe.

RESULTS

GM-CSF stimulated a rapid and transient expression and release of OSM from blood neutrophils, which was more rapid than the expression and release from blood monocytes. A 28-kd protein was identified in cell extracts, but an additional 25-kd isoform was detected in culture supernatants. Synovial fluid neutrophils could not be stimulated to express OSM, but this cytokine was detected in cell-free supernatants at various levels.

CONCLUSION

Blood neutrophils can be stimulated to express and rapidly release large quantities of OSM. We propose that this important cytokine is released from neutrophils as they infiltrate rheumatoid joints and, thus, contribute to the complex cytokine network that characterizes RA.

Measles virus infection of rhesus macaques affects neutrophil expression of IL-12 and IL-10

Cytokine production by phagocytic cells is an important component of the immune response to infection with a variety of pathogens. Neutrophils are phagocytic cells capable of expressing interleukin (IL)-12 and IL-10 in response to infection with parasites, fungi, and bacteria. These cytokines are postulated to play important roles in the immune response during measles. Neutrophils isolated from naive or measles virus (MV)-infected rhesus macaques expressed IL-12 and IL-10 following in vitro stimulation with lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma). Stimulated neutrophils secreted proportionally more of the biologically active IL-12 heterodimer p70 and more IL-10 than similarly stimulated peripheral blood mononuclear cells (PBMCs). During MV infection, the number of IL-12 and IL-10-producing neutrophils and monocytes initially decreased. Subsequently, IL-12 levels were restored, and IL-10 expression rose above baseline in both cell types. Increased IL-10 production by neutrophils and monocytes during MV infection may play a role in measles-induced immunosuppression.

Expression and secretion of ficolin beta by porcine neutrophils

Ficolins are collagenous lectins that bind N-acetylglucosamine (GlcNAc) as well as some bacterial surfaces, and may have opsonic and complement-activating functions. Ficolin alpha in porcine plasma binds Actinobacillus pleuropneumoniae serotype 5 (APP) in a GlcNAc-dependent manner. In the present study, we discovered that porcine neutrophils, but not platelets or mononuclear cells, contained a different ficolin that migrated as a 39-kDa band on SDS-PAGE and resembled a minor component of plasma ficolins that binds APP. However, neutrophil ficolins (pI range 6.4-7.4) were readily distinguished from plasma ficolin alpha (pI 5.2-5.8) by 2D PAGE. Neutrophil ficolin was consistent with ficolin beta by pI and peptide mass fingerprinting with matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Porcine neutrophils expressed ficolin beta, but not ficolin alpha, as determined by RT-PCR. Ficolin beta was present in the membrane and cytoplasmic fractions of nonactivated neutrophils, but the majority of ficolin beta was secreted upon activation with PMA. Ficolin alpha readily bound to intact APP, but ficolin beta did not under the same conditions. These studies demonstrate that neutrophils express ficolin beta and secrete it when activated; however, ficolin beta may have different binding functions than ficolin alpha.

Acute inflammatory response induced byHelicobacter pyloriin the rat air pouch

Infection by Helicobacter pylori elicits persistent neutrophil infiltration in the gastric mucosa and stimulates the release of substances that may contribute to the establishment of gastritis. In this study, we used the rat air pouch model to evaluate the acute inflammatory response to H. pylori, in vivo. A pronounced neutrophil infiltration was observed 6 h and 12 h after the injection of H. pylori into the air pouch. Strains with different genotypes were able to induce cellular influx. This response was dependent upon the amount of bacteria injected and still occurred when heat-killed bacteria were employed. An increase in prostaglandin E(2) levels was observed, indicating that H. pylori induced cyclooxygenase 2 in this model. The production of interleukin-1 beta and tumor necrosis factor-alpha by leukocytes was also enhanced, suggesting that this model may be useful for studying the direct activation of neutrophils by H. pylori in vivo.

Stimulation of neutrophil granulocytes with Mycobacterium bovis bacillus Calmette-Guérin induces changes in phenotype and gene expression and inhibits spontaneous apoptosis

Polymorphonuclear neutrophil granulocytes (PMN) have been implicated in the early inflammatory response against mycobacteria besides monocytes/macrophages. Yet, little is known about the interaction of mycobacteria with PMN. We investigated the potential of Mycobacterium bovis bacillus Calmette-Guérin (BCG) to stimulate and influence PMN phenotype, gene expression profile and spontaneous apoptosis. Flow cytometric analyses revealed an upregulation of the function-associated molecules Fc gamma receptor III (Fc gamma R III) and II (CD16 and CD32) as well as MAC-1 (CD11b and CD18) on BCG-stimulated PMN. As determined by cDNA microarrays and multiplex reverse transcriptase PCR, stimulation with BCG alters the expression of various genes for proinflammatory cytokines/chemokines or receptors in PMN. We detected an upregulation or de novo synthesis of interleukin 1 alpha (IL-1 alpha), IL-1 beta, IL-8, macrophage inflammatory protein 1 alpha (MIP-1 alpha), MIP-1 beta, GRO-alpha, transforming growth factor beta, MCP-1, IL-2 receptor gamma (IL-2R gamma), IL-10R alpha, and IL-6R. Genes for IL-9, IL-12 alpha, IL-15, IL-5R alpha, and IL-13R alpha(1) were found to be downregulated or switched off. Furthermore, Giemsa and annexin V-propidium iodide double staining demonstrated an inhibition of spontaneous PMN apoptosis following BCG stimulation. Changes in phenotype and inhibition of apoptosis did not depend on direct mycobacterial stimulation alone, but were a result of an autocrine-paracrine stimulation mechanism. Our findings support the hypothesis that PMN become activated at the site of mycobacterial infections and that this activation might set the stage for a subsequent antimycobacterial immune response.

Lipopolysaccharide stimulates p38-dependent induction of antiviral genes in neutrophils independently of paracrine factors

Lipopolysaccharide (LPS) induces neutrophils to synthesize and secrete pro-inflammatory cytokines and chemokines, which are regulated at both the transcriptional and translational level. We reported previously that neutrophils stimulated with LPS induce expression of genes typically expressed in response to stimulation with antiviral type I interferons (IFN), such as myxovirus resistance-1 (MX1). However, we present evidence that this response of neutrophils to lipopolysaccharide occurs in the absence of interferon-dependent signaling. Lipopolysaccharide-stimulated neutrophils do not phosphorylate the interferon-associated transcription factors signal transducer and activator of transcription-1 and -3, and medium from lipopolysaccharide-stimulated cells was unable to induce MX1 gene expression, suggesting a soluble factor is not involved. Furthermore, LPS did not alter expression of IFNA and IFNB genes. In contrast to neutrophils, LPS-stimulated human monocyte-derived macrophages induced the expression of MX1, but IFNB was induced, and medium from LPS-stimulated monocyte-derived macrophages supported MX1 induction. An inhibitor of p38 kinase blocked induction of MX1 by lipopolysaccharide, but not IFNalpha, in neutrophils, and induction of MX1 was dependent on protein synthesis. LPS, but not IFNalpha, substantially activated p38. In contrast, the induction of MX1 by LPS in monocyte-derived macrophages was insensitive to p38 inhibition, although p38 is phosphorylated in LPS-stimulated but not IFNalpha-stimulated monocyte-derived macrophages. The expression of MX1 in neutrophils and monocyte-derived macrophages is mediated by TLR4 but not TLR2. The data presented here indicate that lipopolysaccharide activates novel interferon-independent signaling pathways in neutrophils and that induction of antiviral genes is a consequence of exposure of neutrophils to bacterial products.

G-CSF application in patients with severe bacterial pneumonia increases IL-10 expression in neutrophils

In severe pneumonia, the application of granulocyte-colony stimulating factor (G-CSF) was associated with reduced complications possibly by an induction of anti-inflammatory cytokines. It is not clear, whether G-CSF induces interleukin-10 (IL-10) synthesis in neutrophils. In a randomized study, 15 patients with severe community acquired pneumonia were treated either by a single dose of G-CSF and antibiotic therapy (n=8) or antibiotics alone (n=7). Messenger ribonucleic acid (mRNA) expression of IL-10 and tumor necrosis factor alpha of peripheral blood leukocytes was measured using in-situ hybridization (ISH) and reverse-transcription-polymerase-chain-reaction (RT-PCR). In addition, the cytokine release of lipopolysaccharide (LPS)-stimulated whole blood was measured by ELISA. We detected increased IL-10 mRNA by ISH (140 +/- 8% vs. -11 +/- 5%, P<0.01) and RT-PCR (126 +/- 16% vs. -28 +/- 3%, P<0.01) in the G-CSF-treated group only. In contrast, LPS-stimulated whole blood cells in vitro released significantly less IL-10 compared to the control group (-38.2 +/- 97 vs. -14.8 +/- 6 pg/ml, P<0.02). There was no significant effect on IL-10 serum protein levels and the TNF-alpha release and expression. IL-10 mRNA was detected predominantly in cluster designation 66b (CD66b) positive nucleated blood cells indicating that polymorphonuclear leukocytes are the main source of IL-10 expression after G-CSF stimulation. G-CSF induces transcription of IL-10 mRNA in neutrophils without increased release. This may be due to posttranscriptional effects.

Plasma and neutrophil fatty acid composition in advanced cancer patients and response to fish oil supplementation

Metabolic demand and altered supply of essential nutrients is poorly characterised in patients with advanced cancer. A possible imbalance or deficiency of essential fatty acids is suggested by reported beneficial effects of fish oil supplementation. To assess fatty acid status (composition of plasma and neutrophil phospholipids) in advanced cancer patients before and after 14 days of supplementation (12+/-1 g day(-1)) with fish (eicosapentaenoic acid, and docosahexaenoic acid) or placebo (olive) oil. Blood was drawn from cancer patients experiencing weight loss of >5% body weight (n=23). Fatty acid composition of plasma phospholipids and the major phospholipid classes of isolated neutrophils were determined using gas liquid chromatography. At baseline, patients with advanced cancer exhibited low levels (<30% of normal values) of plasma phospholipids and constituent fatty acids and elevated 20 : 4 n-6 content in neutrophil phospholipids. High n-6/n-3 fatty acid ratios in neutrophil and plasma phospholipids were inversely related to body mass index. Fish oil supplementation raised eicosapentaenoic acid and docosahexaenoic acid content in plasma but not neutrophil phospholipids. 20 : 4 n-6 content was reduced in neutrophil PI following supplementation with fish oil. Change in body weight during the supplementation period related directly to increases in eicosapentaenoic acid in plasma. Advanced cancer patients have alterations in lipid metabolism potentially due to nutritional status and/or chemotherapy. Potential obstacles in fatty acid utilisation must be addressed in future trials aiming to improve outcomes using nutritional intervention with fish oils.

Effect of soluble interleukin-6 receptor alpha and interleukin-6 secreted by polymorphonuclear leukocytes on tumor necrosis factor-alpha expression and its production by peripheral blood mononuclear cells

BACKGROUND

It has recently been shown that soluble interleukin-6 receptor (sIL-6R) alone or complexed with interleukin (IL)-6, besides their regulatory role in a wide variety of both normal and abnormal biologic reactions mediated by IL-6, could be an effective stimulator of the cell function.

AIMS

The key question of the present study is whether the sIL-6Ralpha or sIL-6R with IL-6 released by polymorphonuclear leukocytes (PMN) can influence cytokine secretion such as tumor necrosis factor-alpha (TNF-alpha) by peripheral blood mononuclear cells (PBMC), which together with PMN develop the inflammatory and immune response of a host.

METHODS

Cells were isolated from heparinized whole blood of healthy persons. The PMN were cultured for 1 h at 37 degrees C in 5% CO(2). After incubation, the culture supernatant of PMN was removed and was added to PBMC. The PBMC were cultured for 1 h at 37 degrees C in the same conditions. In the culture supernatants and lysates of PMN, we examined the concentrations of sIL-6R by enzyme-linked immunosorbent assay (ELISA). TNF-alpha was measured at both protein and mRNA levels. Protein levels were determined by ELISA. To examine TNF-alpha mRNA expression, we isolated mRNA from PBMC after culture, using TRIZOL Reagent. The quantity of mRNA TNF-alpha was determined by the Quantikine mRNA assay.

RESULTS AND CONCLUSION

The results obtained revealed that sIL-6R with IL-6 secreted by PMN may play a regulatory role in the immune response by modulating the TNF-alpha expression and its production by PBMC. This may have a significant influence on an early phase of the inflammation and other reactions mediated by TNF-alpha.