The reactivity of neutrophils at the site of an acute inflammatory reaction as measured by chemiluminescence

In this study the technique of luminol-enhanced chemiluminescence (LECL), which was shown to be dependent on the generation of superoxide anion, has been employed to investigate the reactivity of polymorphonuclear leukocytes found at the site of inflammation. Cells derived from the pleural cavity of rats undergoing an acute inflammatory reaction initiated by an intrapleural injection of calcium pyrophosphate or normal serum demonstrated a significantly higher chemiluminescent response compared to cells derived from animals injected with plasma, saline or phosphate-buffered saline. In additionin vitro studies showed that calcium pyrophosphate crystals could stimulate the cellsper se and could increase their reactivity.     

An experimental model to study blood and inflammatory neutrophils

We sought to develop an experimental animal model in order to study the effects of hypothermia on host defences under conditions which were similar to those used for humans. We required a large animal which could tolerate arterial and venous catheters and serial blood sampling without significantly altering its blood volume and blood pressure. The animal should be intubated and ventilated to control blood gases and fluid and electrolyte balance.

Finally the model should have anatomic, metabolic and physiologic similarities to humans. We describe an experimental pig model which appears to fulfill these criteria and provide important information relevant to man.     

An experimental model to study blood and inflammatory neutrophils

We sought to develop an experimental animal model in order to study the effects of hypothermia on host defences under conditions which were similar to those used for humans. We required a large animal which could tolerate arterial and venous catheters and serial blood sampling without significantly altering its blood volume and blood pressure. The animal should be intubated and ventilated to control blood gases and fluid and electrolyte balance.

Finally the model should have anatomic, metabolic and physiologic similarities to humans. We describe an experimental pig model which appears to fulfill these criteria and provide important information relevant to man.     

Dexmedetomidine decreases the inflammatory response to myocardial surgery under mini-cardiopulmonary bypass

Cardiopulmonary bypass (CPB) with extracorporeal circulation produces changes in the immune system accompanied by an increase in proinflammatory cytokines and a decrease in anti-inflammatory cytokines. We hypothesize that dexmedetomidine (DEX) as an anesthetic adjuvant modulates the inflammatory response after coronary artery bypass graft surgery with mini-CPB. In a prospective, randomized, blind study, 12 patients (4 females and 8 males, age range 42-72) were assigned to DEX group and compared with a conventional total intravenous anesthesia (TIVA) group of 11 patients (4 females and 7 males). The endpoints used to assess inflammatory and biochemical responses to mini-CPB were plasma interleukin (IL)-1, IL-6, IL-10, interferon (INF)-γ, tumor necrosis factor (TNF)-α, C-reactive protein, creatine phosphokinase, creatine phosphokinase-MB, cardiac troponin I, cortisol, and glucose levels. These variables were determined before anesthesia, 90 min after beginning CPB, 5 h after beginning CPB, and 24 h after the end of surgery. Endpoints of oxidative stress, including thiobarbituric acid reactive species and delta-aminolevulinate dehydratase activity in erythrocytes were also determined. DEX+TIVA use was associated with a significant reduction in IL-1, IL-6, TNF-α, and INF-γ (P<0.0001) levels compared with TIVA (two-way ANOVA). In contrast, the surgery-induced increase in thiobarbituric acid reactive species was higher in the DEX+TIVA group than in the TIVA group (P<0.01; two-way ANOVA). Delta-aminolevulinate dehydratase activity was decreased after CPB (P<0.001), but there was no difference between the two groups. DEX as an adjuvant in anesthesia reduced circulating IL-1, IL-6, TNF-α, and INF-γ levels after mini-CPB. These findings indicate an interesting anti-inflammatory effect of DEX, which should be studied in different types of surgical interventions.     

Integration of inflammatory signals by rolling neutrophils

Summary: In inflammation, neutrophils roll along the endothelial wall of postcapillary venules and sample inflammatory signals. Neutrophil activation is required to generate β₂ integrin bonds with the endothelium that are strong enough to withstand the flow forces and thus achieve arrest from the rolling state. Unlike naïve T cells, neutrophils are not only activated by ligation of G-protein coupled receptors with chemokines and other chemoattractants but also receive signals from engagement of adhesion molecules including the selectins and β₂ integrins. Rolling neutrophils integrate the sum total of inputs received while scanning the inflamed endothelium. In this process, the velocity of rolling neutrophils systematically decreases as a function of their contact time with the inflamed endothelium. If an activation threshold is reached, β₂ integrins switch to the high-affinity conformation, redistribute on the cell surface, and trigger arrest and adhesion. Rolling cells that do not reach the activation threshold detach from the endothelium and are released back into the circulation. The role of chemokines, adhesion molecules, and other activating inputs involved in this response as well as signaling pathways are the subjects of ongoing investigations. This review provides a conceptual framework for neutrophil recruitment from the flowing blood.     

Human neutrophils switch to an activated phenotype after homing to the lung irrespective of inflammatory disease

Systemic inflammation can be investigated by changes in expression profiles of neutrophil receptors. Application of this technology for analysis of neutrophil phenotypes in diseased tissues is hampered by the absence of information regarding the modulation of neutrophil phenotypes after extravasation to tissues under non‐inflammatory conditions. To fill this gap we measured the expression of neutrophil receptors in bronchoalveolar lavage fluid (BALF) and in the peripheral blood of healthy volunteers, which included both smokers and non‐smokers. Blood and BALF neutrophils were identified by CD16^bright/CD45^dim cells, and triple‐stained with antibodies directed against integrins, chemokine‐ and Fcγ‐receptors. BALF neutrophils of healthy volunteers showed an activated phenotype characterized by Mac‐1 (CD11b)^bright, L‐selectin (CD62L)^dim, intrecellular adhesion molecule 1 (ICAM‐1) (CD54)^bright, FcγRII (CD32)^bright, C5a receptor (CD88)^bright and CD66b^bright. A similar phenotype was observed for BALF neutrophils of patients affected by sarcoidosis. Furthermore, our results demonstrate a modulated expression of C5a receptor (CD88) and ICAM‐1 (CD54) in neutrophils of sarcoidosis patients. In conclusion, our data indicate that neutrophils found in the lung exhibit an activated phenotype under both homeostatic and inflammatory conditions.     

Role of neutrophils in the pathogenesis of acute inflammatory liver injury

Polymorphonuclear leukocytes (neutrophils) are essential in the defense against invading microorganisms, tissue trauma or any inciting inflammatory signals. Hepatic infiltration of neutrophils is an acute response to recent or ongoing liver injury, hepatic stress or unknown systemic inflammatory signals. Once neutrophils reach the liver, they can cause mild-to-severe tissue damage and consequent liver failure. For neutrophils to appear in the liver, neutrophils have to undergo systemic activation (priming) by inflammatory mediators such as cytokines, chemokines, complement factors, immune complexes, opsonized particles and other biologically active molecules, e.g., platelet activating factor. Neutrophils accumulated in the hepatic microvasculature (sinusoids and postsinusoidal venules) can extravasate (transmigrate) into the hepatic parenchyma if they receive a signal from distressed cells. Transmigration can be mediated by a chemokine gradient established towards the hepatic parenchyma and generally involves orchestration by adhesion molecules on neutrophils (beta(2) integrins) and on endothelial cells (intracellular adhesion molecules, ICAM-1). After transmigration, neutrophils adhere to distressed hepatocytes through their beta(2) integrins and ICAM-1 expressed on hepatocytes. Neutrophil contact with hepatocytes mediate oxidative killing of hepatocytes by initiation of respiratory burst and neutrophil degranulation leading to hepatocellular oncotic necrosis. Neutrophil-mediated liver injury has been demonstrated in a variety of diseases and chemical/drug toxicities. Relevant examples are discussed in this review.     

Crucial role of neutrophils in the development of mechanical inflammatory hypernociception

Neutrophil migration is responsible for tissue damage observed in inflammatory diseases. Neutrophils are also implicated in inflammatory nociception, but mechanisms of their participation have not been elucidated. In the present study, we addressed these mechanisms in the carrageenan-induced mechanical hypernociception, which was determined using a modification of the Randall-Sellito test in rats. Neutrophil accumulation into the plantar tissue was determined by the contents of myeloperoxidase activity, whereas cytokines and PGE(2) levels were measured by ELISA and radioimmunoassay, respectively. The pretreatment of rats with fucoidin (a leukocyte adhesion inhibitor) inhibited carrageenan-induced hypernociception in a dose- and time-dependent manner. Inhibition of hypernociception by fucoidin was associated with prevention of neutrophil recruitment, as it did not inhibit the hypernociception induced by the direct-acting hypernociceptive mediators, PGE(2) and dopamine, which cause hypernociception, independent of neutrophils. Fucoidin had no effect on carrageenan-induced TNF-alpha, IL-1beta, and cytokine-induced neutrophil chemoattractant 1 (CINC-1)/CXCL1 production, suggesting that neutrophils were not the source of hypernociceptive cytokines. Conversely, hypernociception and neutrophil migration induced by TNF-alpha, IL-1beta, and CINC-1/CXCL1 was inhibited by fucoidin, suggesting that neutrophils are involved in the production of direct-acting hypernociceptive mediators. Indeed, neutrophils stimulated in vitro with IL-1beta produced PGE(2), and IL-1beta-induced PGE(2) production in the rat paw was inhibited by the pretreatment with fucoidin. In conclusion, during the inflammatory process, the migrating neutrophils participate in the cascade of events leading to mechanical hypernociception, at least by mediating the release of direct-acting hypernociceptive mediators, such as PGE(2). Therefore, the blockade of neutrophil migration could be a target to development of new analgesic drugs.     

全身炎性反应综合征中性粒细胞线粒体细胞色素c的研究进展

全身炎性反应综合征(systemic inflammation response syndrome,SIRS)是多种疾病发展至多器官功能障碍综合征(multiple organs dysfunction syndrome,MODS)的前期表现.中性粒细胞,又名多形核白细胞(polymorphonuclear neutrophil,PMN)是重要的炎症效应细胞,其凋亡延迟或障碍进而导致炎症反应持续发展和加剧是SIRS的主要病理生理过程.线粒体细胞色素c(cytochrome c,Cyt-c)是重要的凋亡蛋白,通过内源性和外源性等多种凋亡途径参与PMN凋亡.深入探讨SIRS时PMN凋亡异常的分子机制,研究线粒体Cyt-c在PMN凋亡中的作用,寻找诱导PMN适时、适度凋亡的有效方法,对于限制组织损伤、控制炎症反应、减轻SIRS有重要意义.     

Hyaluronidase,from wound healing to cancer

An explanation is proposed as to how the total amount of cells normally are in a cellular equilibrium which results from an energetic equilibrium.When a group of cells is damaged the body can restore this disturbance by the fight and flight reaction-a mechanism in which the circulating body energy is redistributed and in which all body cells are involved cooperatively. An unfavourable side-effect of this mechanism is a diminished uptake of nutrients from the gastro-intestinal tract. Therefore in chronic irritation, cachexia and a decreased resistance to all forms of insult occurs. The energetic equilibirum becomes severely disturbed.Differentiation from a morula cell to a ripe cell is proposed to be an expression of a decreased nutrient supply to the morula. The predominant mechanism for cellular survival is a change from a demand on nutrient supply to a demand on the specialisation of the cell function. The role of the nutrient supply — regulated by hyaluronidase synthesis — then becomes subsidiary to this specific function.It is proposed that cancer originates because of chronic irritation. As a result of the secondary chronic redistribution of body energy in the direction of the irritated area, these cells are chronically hypernourished and then dedifferentiate again in the direction of the morula cell. As a consequence of the reactive mechanism, the cachexia, which is so typical of cancer, then occurs.From theoretical considerations, it is predictable that cancer may be effectively treated by two basic manipulations of the energetic equilibrium: firstly by xhronically decreasing the nutrient supply to the cancer cells, thereby stimulating differentiation again, and secondly by restoring the energetic equilibrium. In practive this involves supplementation of hyaluronidase together with hyperalimentation.     

Transient infiltration of neutrophils into the thymus in association with apoptosis induced by whole-body X-irradiation

Generally, the process of apoptosis does not cause leakage of noxious cytosolic contents and is therefore non-inflammatory. However, as previously shown, macrophages ingesting apoptotic CTLL-2 cells produced pro-inflammatory cytokines, particularly interleukin-8 (IL-8) and macrophage inflammatory protein-2 (MIP-2), a murine IL-8 homolog. This predicted that rapid and massive apoptosis may induce neutrophil accumulation in vivo. In this study, we tested this prediction by inducing apoptosis by whole-body X-irradiation in mice. After exposure to 4 Gy X-ray irradiation, mice exhibited considerable apoptosis of thymic cells, which was associated with transient infiltration of neutrophils as well as MIP-2 mRNA expression. In contrast, in p53-deficient mice in which irradiation-induced apoptosis was suppressed, as has been reported, infiltration of neutrophils into the thymus was less than that found in p53+/+ mice. Taken together, these results suggest that massive and rapid apoptosis can result in infiltration of neutrophils.     

In vivo suppressive function of myeloid-derived suppressor cells is limited to the inflammatory site

Current paradigms suggest that, despite the heterogeneity of myeloid-derived suppressor cells (MDSC), all Gr-1(+) CD11b(+) cells can exert suppressive function when exposed to inflammatory stimuli. In vitro evaluation shows that MDSC from multiple tissue sites have suppressive activity, and in vivo inhibition of MDSC enhances T-cell function; however, the relative capacity of MDSC present at localized inflammatory sites or in peripheral tissues to suppress T-cell responses in vivo has not been directly evaluated. In the current study, we observed that during a tissue-specific inflammatory response, MDSC inhibition of CD8(+) T-cell proliferation and IFN-γ production was restricted to the inflammatory site. Using a prostate-specific inflammatory model and a heterotopic prostate tumor model, we showed that MDSC from inflammatory sites or from tumor tissue possess immediate capacity to inhibit T-cell function, whereas those isolated from peripheral tissues (spleens and liver) were not suppressive without activation of iNOS by exposure to IFN-γ. These data suggest that MDSC are important regulators of immune responses in the prostate during acute inflammation and the chronic inflammatory setting of tumor growth, and that regulation of T-cell function by MDSC during a localized inflammatory response is restricted in vivo to the site of an ongoing immune response.     

Amb a 1-immunostimulatory oligodeoxynucleotide conjugate immunotherapy decreases the nasal inflammatory response

BACKGROUND: Amb a 1-immunostimulatory phosphorothioate oligonucleotide conjugate (AIC) is a novel immunotherapeutic compound consisting of purified Amb a 1 from short ragweed proteins covalently linked to an immunostimulatory phosphorothioate oligodeoxyribonucleotide. In sensitized animals AIC can stimulate an Amb a 1-specific T(H)1 response and decrease pulmonary reactivity to ragweed challenge. Clinical trials have documented reduced allergic response to AIC in comparison with licensed ragweed extract. OBJECTIVES: We sought to determine the in vivo effect of short-course immunotherapy with AIC on eosinophilia and cytokine mRNA expression in the nasal mucosa of ragweed-sensitive patients. METHODS: Ragweed-sensitive patients with allergic rhinitis were treated with 6 escalating doses of AIC (0.06-12 microg, n = 28) or placebo (n = 29) at weekly intervals immediately before the 2001 ragweed season. Symptom scores and medication use were recorded for the 2001 and 2002 ragweed seasons for all patients. A subset of patients (12 receiving AIC and 7 receiving placebo) consented to have nasal biopsy specimens taken before immunization and before and after the first ragweed season. The preseason and postseason biopsy specimens were taken 24 hours after ragweed allergen challenge and compared with the initial unchallenged biopsy specimen to assess cytokine and inflammatory cell responses by using immunocytochemistry and in situ hybridization. RESULTS: AIC was safe and well tolerated by all patients. There was no difference between the AIC and placebo groups in the number of allergen-induced major basic protein-, IL-4-, IL-5-, or IFN-gamma-positive cells in the mucosa in the first weeks after AIC immunization. On rechallenge and rebiopsy after the end of the 2001 ragweed season, however, AIC-treated patients had a significantly reduced increase in eosinophils and IL-4 mRNA-positive cells and an increased number of IFN-gamma mRNA-positive cells compared with placebo-treated patients. No difference between treatment groups was observed in symptom scores or medication use during the first ragweed season. During the second ragweed season, however, there was a significant decrease in chest symptoms and a trend toward reduced nasal symptoms in the AIC-treated group. CONCLUSION: Short-course immunotherapy with AIC can modify the response of nasal mucosa to allergen challenge by increasing T(H)1 cytokine production and decreasing T(H)2 cytokine production and eosinophilia. This modification was not immediate but was observed 4 to 5 months after completion of immunotherapy and seasonal ragweed-pollen exposure. The T-cell subset shift after immunization and seasonal exposure was followed by evidence of clinical efficacy in the second ragweed season without additional AIC immunizations.     

Immune and regulatory functions of neutrophils in inflammatory bone loss

Although historically viewed as merely anti-microbial effectors in acute infection or injury, neutrophils are now appreciated to be functionally versatile with critical roles also in chronic inflammation. Periodontitis, a chronic inflammatory disease that destroys the tooth-supporting gums and bone, is particularly affected by alterations in neutrophil numbers or function, as revealed by observations in monogenic disorders and relevant mouse models. Besides being a significant debilitating disease and health burden in its own right, periodontitis is thus an attractive model to dissect uncharted neutrophil-associated (patho)physiological pathways. Here, we summarize recent evidence that neutrophils can contribute to inflammatory bone loss not only through the typical bystander injury dogma but intriguingly also through their absence from the affected tissue, where they normally perform important immunomodulatory functions. Moreover, we discuss recent advances in the interactions of neutrophils with the vascular endothelium and – upon extravasation – with bacteria, and how the dysregulation of these interactions leads to inflammatory tissue damage. Overall, neutrophils have both protective and destructive roles in periodontitis, as they are involved in both the maintenance of periodontal tissue homeostasis and the induction of inflammatory bone loss. This highlights the importance of developing approaches that promote or sustain a fine balance between homeostatic immunity and inflammatory pathology.