Insulin inhibits phagocytosis in normal human neutrophils via PKCα/β-dependent priming of F-actin assembly

Objective: This study investigated the effects of insulin on the phagocytosis of C3bi – and IgG-opsonized yeast particles in normal human neutrophils. Methods: Neutrophils were incubated in different insulin concentrations for 30 minutes and stimulated by C3bi – or IgG-opsonized yeast particles. Phagocytosis was quantified by both light microscopy and FACscan flow cytometry. Laser confocal microscopy was used for quantification of F-actin levels. Results: Elevated insulin concentrations decreased neutrophil phagocytosis of both types of targets. This defect was shown to be in part due to a delayed phagocytosis in the presence of insulin. Following a 30 minute incubation, insulin was found to increase the accumulation of cortical F-actin, without affecting the total cellular F-actin content. The specific PKCα/β inhibitor, Go6976, abolished the insulin-mediated increase in cortical F-actin content and both Go6976 and the PKCα/β/δ/ε-specific inhibitor GF109203X reversed the inhibitory effects of insulin on phagocytosis. Conclusion: Hyperinsulinemia in vitro can inhibit phagocytosis of opsonized targets in normal human neutrophils. This effect of insulin is dependent on activation of PKCα and/or PKCβ, and these insulin signals may interfere with the dynamic assembly/disassembly and/or distribution of F-actin, which is required for the phagocytosis process. Received 8 July 2005; accepted 13 October 2005 without revision I. Ahnfelt-R?nne     

Tumor‐induced myeloid‐derived suppressor cell subsets exert either inhibitory or stimulatory effects on distinct CD8+ T‐cell activation events

Tumor growth coincides with an accumulation of myeloid‐derived suppressor cells (MDSCs), which exert immune suppression and which consist of two main subpopulations, known as monocytic (MO) CD11b⁺CD115⁺Ly6G^?Ly6C^high MDSCs and granulocytic CD11b⁺CD115^?Ly6G⁺Ly6C^int polymorphonuclear (PMN)‐MDSCs. However, whether these distinct MDSC subsets hamper all aspects of early CD8⁺ T‐cell activation — including cytokine production, surface marker expression, survival, and cytotoxicity — is currently unclear. Here, employing an in vitro coculture system, we demonstrate that splenic MDSC subsets suppress antigen‐driven CD8⁺ T‐cell proliferation, but differ in their dependency on IFN‐γ, STAT‐1, IRF‐1, and NO to do so. Moreover, MO‐MDSC and PMN‐MDSCs diminish IL‐2 levels, but only MO‐MDSCs affect IL‐2Rα (CD25) expression and STAT‐5 signaling. Unexpectedly, however, both MDSC populations stimulate IFN‐γ production by CD8⁺ T cells on a per cell basis, illustrating that some T‐cell activation characteristics are actually stimulated by MDSCs. Conversely, MO‐MDSCs counteract the activation‐induced change in CD44, CD62L, CD162, and granzyme B expression, while promoting CD69 and Fas upregulation. Together, these effects result in an altered CD8⁺ T‐cell adhesiveness to the extracellular matrix and selectins, sensitivity to FasL‐mediated apoptosis, and cytotoxicity. Hence, MDSCs intricately influence different CD8⁺ T‐cell activation events in vitro, whereby some parameters are suppressed while others are stimulated.     

TNF-α、IL-1β 、LPS对人多核白细胞、脐静脉内皮细胞血小板内皮细胞粘附分子-1表达的影响

目的：初探炎性刺激对人多核白细胞（ＰＭＮ）和脐静脉内皮细胞（ＨＵＶＥＣ）的血小板内皮细胞粘附分子－１（ＰＥＣＡＭ－１）表达的影响和ＰＥＣＡＭ－１的可能作用。方法：使用流式细胞仪和免疫组化法,观察脂多糖（ＬＰＳ）、白介素（ＩＬ）－１β和肿瘤坏死因子（ＴＮＦ）－ａ对ＰＭＮ和ＨＵＶＥＣ ＰＥＣＡＭ－１表达的变化。结果：ＬＰＳ、１Ｌ－１β和ＴＮＦ－ａ可引起ＰＭＮ表达ＰＥＣＡＭ－１蛋白减少,而对ＨＵＶＥＣ　ＰＥＣＡＭ－１的表达无显著影响,但组化显著在ＨＵ－ＶＥＣ连接部的ＰＥＣＡＭ－１染色变淡。结论：上述炎性刺激物不仅可引起ＰＭＮ表达ＰＥＣＡＭ－１减少、激活ＰＭＮ,而且可改变内皮细胞ＰＥＣＡＭ－１的分布,因此ＰＥＣＡＭ－１在炎症中可能起重要作用。     

Acute chorioamnionitis and intra-amniotic inflammation are more severe according to outside-in neutrophil migration within the same chorio-decidua

ObjectiveNo information exists about whether acute histologic chorioamnionitis (acute-HCA) is more advanced and severe, and intra-amniotic inflammation is more frequent and intense according to outside in neutrophil migration within the same chorio-decidua. The objective of current study is to examine this issue.Materials and methodsWe included 106 singleton preterm-births (gestational age at delivery: 20–34 weeks) due to either preterm-labor or preterm-PROM in the context of acute chorio-deciduitis. Study-population was divided into 3 groups according to outside-in neutrophil migration within chorio-decidua as follows: 1) group-1: ‘inflammation restricted to the decidua’ (n = 22); 2) group-2: ‘inflammation restricted to the MT of chorion and the decidua’ (n = 31); 3) group-3: ‘inflammation in the CT of chorion’ (n = 53). We examined the frequency of inflammation in each placental compartment beyond chorio-decidua (i.e., amnion, umbilical cord, and chorionic-plate), and total grade (1–8) of acute-HCA. Moreover, the frequency of intra-amniotic infection (defined as positive amniotic-fluid culture for aerobic and anaerobic bacteria and genital mycoplasmas) and intra-amniotic inflammation (defined as amniotic fluid WBC ≥ 19 cells/mm³), and an intra-amniotic inflammatory response gauged by amnioticfluid WBC count (cells/mm³) were examined in 50 amniotic fluid samples within 7 days of birth.ResultsAmnionitis, funisitis and chorionic plate inflammation were more frequent (each for P < 0.01) and median total grade of acute-HCA was increased (P < 0.001) according to outside-in neutrophil migration within chorio-decidua (group-1vs.group-2vs.group-3). Moreover, intra-amniotic infection and inflammation were more frequent (each-for P < 0.05) and median amniotic-fluid WBC count was increased (P < 0.01) according-to outside-in neutrophil-migration within chorio-decidua (group-1 vs. group-2 vs. group-3).ConclusionAcute-HCA is more advanced and severe, and intra-amniotic inflammation is more frequent and intense according to outside in neutrophil migration within the same chorio-decidua. This finding suggests that what is now acute chorio-deciduitis should be subdivided.     

Alternations of surface antigens on leukocytes after severe injury: correlation with infectious complications

Objective: To investigate the alternations of surface antigens of leukocytes after severe injury and the correlation with clinical outcome. Setting: Emergency Department and Intensive Care Unit of a university hospital. Patients: Patients with severe trauma (injury severity score > 16) were enrolled. Those who were transferred or had critical injuries were excluded. Measurements and results: Polymorphonuclear cells (PMN) and mononuclear cells (MN) were isolated from patients on the 1st, 3rd and 7th day following injury. The mean fluorescent expressions of CD11b and CD16 of PMN, and CD25 of MN were measured and compared with those obtained from paralleled controls. Sixteen injured patients were included. The CD11b expressions of PMN increased on the 1st day and were still high on the 7th day. The CD16 expressions decreased on the 1st day and CD25 decreased on the 3rd day; both were still low on the 7th day. Six patients developed infectious complications. CD11b expression remained high and CD16 expression remained low on three measurements of the infectious patients, whereas both expressions recovered on the last measurement of non-infectious patients. CD25 expression remained low in both groups. Three infectious patients with pneumonia died from mutiple organ failure. Conclusion: Phenotypic alternations of leukocytes develop early after severe injury. The alternations may represent a state of activation of PMN and subsequent suppression of IL-2 related immunity. Persistent activation of PMN with enhanced CD11b and attenuated CD16 expression indicates the development of infectious complications and a poor prognosis can be anticipated if the infectious sites can not be controlled early. Received: 22 November 1996 Accepted: 13 November 1997     

Dust exposure, eye redness, eye cytology and mucous membrane irritation in a tobacco industry

Summary In a study of 75 workers employed in a tobacco factory producing cheroots we measured cellular contents of tear fluid, redness of eyes, discomfort, total (0–5.7 mg/m³) and respirable dust in the breathing zone and total ambient dust by stationary sampling (0.08–1.0 mg/m³). A matched group of 50 office workers in a telephone company (total ambient dust concentration between 0.08–0.13 mg/m³) was similarly examined as referents. We found a difference between the two companies with regard to cell counts, with tobacco workers having the largest numbers except for lymphocytes. Among tobacco workers we furthermore found that the number of cuboidal and columnar epithelial cells increased during the day. The increase of cuboidal cells, however, occurred mainly in a small group of tobacco workers exposed to the highest concentrations of tobacco dust (mean =1.26 mg/m³). No difference in the sensation of eye irritation was found between companies, but increased irritation in the morning was associated with increased exposure to total dust during the work-shift among tobacco workers. A dose-dependent difference in photographically measured eye redness was found among the tobacco workers. It could not be explained by differences in tobacco smoking, sex, age, sleeping habits or use of glasses. Irritation of lips and upper airways as reported by questionnaire were more common in tobacco workers than in referents. In conclusion the tobacco workers, more often than the referents, had complaints and objective changes in the mucous membranes of the eyes. These may be related to tobacco dust exposure.     

Neutrophil interactions with endothelium and platelets: possible role in the development of cardiovascular injury

Polymorphonuclear neutrophils (PMN) cause myocardial injuryduring ischaemia and reperfusion by their direct effects onthe myocardium; PMN release highly cytotoxic free oxygen radicalsand proteolytic enzymes and PMN aggregates are involved in capillaryplugging and the no-reflow phenomenon. In addition, PMN-derivedfactors including free oxygen radicals, lipoxygenase products,cytokines and proteolytic enzymes have been shown to modifythe function of endothelium and platelets. However, both endotheliumand platelets are capable of modulating PMN activation. Endothelialcells modulate PMN function by the expression of adhesion moleculesand by release of soluble factors including nitric oxide, prostacyclin,endothelins, platelet activating factor and interleukin-8. Plateletsaffect PMN activation by release of thromboxane A₂, plateletderived growth factor, serotonin, lipoxygenase products, proteasesand adenosine. Thus, in addition to their direct injurious effecton ischaemic myocardium, neutrophils are involved in the functionalbalance between endothelium and platelets and exert an indirecteffect on the myocardium.     

Impairment of Polymorphonuclear Leucocyte Function during Therapy with Synthetic ACTH in Children Affected by Epileptic Encephalopathies

ABSTRACT. Therapy with synthetic ACTH (zinc tetracosactide) in children affected by epileptic encephalopathy is often associated with a large number of infectious complications. We studied the phagocytic activity of polymorphonuclear leucocytes (PMN) in 9 children with West or Lennox-Gastaut syndrome, measuring PMN superoxide anion production during the phagocytosis of particles of Zymosan and after phorbol miristate acetate (PMA) stimulation. The test was performed before, during and after therapy with zinc tetracosactide (0.02 mg/kg/day for 15 days). At the same time plasma immunoglobulins, C3, C4, C3 activator and Cortisol were determined. During treatment PMN phagocytic function was significantly reduced but returned to normal levels after suspension of therapy. The other hematological parameters considered remained within the normal range. During the follow-up of the patients we observed 15 infectious episodes (3 mucocutaneous candidiasis, 2 enterocolitis, 4 urinary tract infections, 1 otitis media, 3 bronchiolitis, 2 pneumonia). One of the patients died of a bilateral pneumonia. Three children were treated with ACTH on alternating days. In these patients PMN phagocytic activity was less impaired and 2 infectious episodes rapidly resolved. Alternate day ACTH therapy seems to be preferable.     

Anti-oxidant effects of retinoids on inflammatory skin diseases

Summary It is well known that retinoids are effective in the treatment of various dermatological disorders. It has been reported that retinoids have inhibitory effects on the generation of superoxide (O ₂ ^- ) by stimulated polymorphonuclear leukocytes (PMNs). In the present study, we investigated the effects of retinoids on the generation of O ₂ ^- and other reactive oxygen species (ROS), including OH, H₂O₂ and chemiluminescence, by zymosan-stimulated PMNs and in the xanthinexanthine oxidase system, because these potent ROS may play an important role in PMN-mediated skin inflammation. It was found that some retinoids had anti-oxidant effects in the PMN system; however, apart from the effect of tretinoin and Ro 10-1670 on OH generation, none of the retinoids studied inhibited ROS generation in the xanthine-xanthine oxidase system. On the basis of these results, we discuss a possible mechanism connected with the role of ROS by which retinoids have favourable effects on several inflammatory skin disorders.     

Can hydroxyapatite deposition in the eye cause a neutrophil-related inflammatory reaction?

Patients with chronic renal failure on intermittent dialysis sometimes develop an acute diffuse conjunctival and episcleral hyperaemia. In this study the hypothesis was tested whether the precipitation of hydroxyapatite crystals could result in an inflammatory reaction mediated by enzymes liberated from polymorphonuclear leucocytes (PMN). Ingestion of the crystals by PMN's can result in cell death and membranolysis and subsequent release of intracellular enzymes into the surrounding tissues. This suicide sac hypothesis for the inflammatory reactions of the conjunctiva and episclera was rejected after histopathological examination of conjunctival biopsies failed to show complement activation or crystal ingestion by PMN's despite the presence of small subepithelial hydroxyapatite crystals.