CD11/CD18-independent neutrophil adherence to laminin is mediated by the integrin VLA-6.

Regulated adherence of polymorphonuclear leukocytes (PMNs) to endothelium and subendothelial matrix is a critical event for PMN localization at and migration into inflammatory sites. We previously reported that human PMNs stimulated in vitro adhere to laminin, the major glycoprotein of mammalian basement membrane, by both CD11/CD18 (beta 2 integrin)-dependent and CD11/CD18-independent mechanisms. This CD11/CD18-independent adherence is inhibited by monoclonal antibodies (MoAbs) directed against the beta 1 subunit of integrins (very late antigens [VLA]). The specific PMN VLA receptor responsible for stimulated CD11/CD18-independent PMN adherence to laminin was not elucidated. We show here that this CD11/CD18-independent adherence is mediated by a member of the beta 1 integrins, VLA-6. MoAbs GoH3 and 450-30, which bind the alpha 6 subunit of VLA-6, significantly reduced adherence of phorbol myristate acetate-stimulated PMNs to laminin-coated surfaces when CD11/CD18-independent adherence was blocked with anti-CD11/CD18 MoAbs. Furthermore, GoH3 completely inhibited stimulated adherence of CD11/CD18-deficient PMNs to laminin. Analysis by flow cytometry showed that human PMNs express VLA-6. The PMN alpha 6 is identical in size and pl to the platelet alpha 6, but the PMN beta 1 exhibits considerable heterogeneity in molecular weight compared with the platelet beta 1. This activation-dependent adherence receptor for laminin may play a role in PMN interaction with basement membrane laminin during PMN movement through vascular walls.     

Hydrogen peroxide pretreatment of perfused canine vessels induces ICAM-1 and CD18-dependent neutrophil adherence.

BACKGROUND. Cytotoxic products of neutrophils (polymorphonuclear leukocytes, PMNs) contribute to ischemia-reperfusion injury of several tissues. Hydrogen peroxide (H2O2), one of the cytotoxic products of PMNs, also promotes the adherence of PMNs to cultured vascular endothelial cells in vitro. The present study was undertaken to determine if H2O2 also augmented adhesion of PMNs to intact vessels perfused ex vivo and to determine if H2O2-induced PMN adherence to intact canine carotid arteries and external jugular veins or to cultured canine venous endothelium is mediated by specific adherence ligands on the neutrophil and/or the endothelium. METHODS AND RESULTS. Vessels were perfused for 20 minutes with oxygenated Krebs-Henseleit bicarbonate buffer with and without H2O2, washed with buffer alone, and then exposed to 111In-labeled isolated PMNs (10(7) cells/vessel) under static conditions for up to 20 minutes before being washed again. Residual radioactivity retained by the washed vessel was counted as an index of PMN retention. The adherence of unlabeled PMNs to cultured endothelial cells was determined by a visual assay method after pretreatment of the endothelium with H2O2 for brief periods followed by washing. Perfusion of vessels with H2O2 produced a transient, concentration-dependent increase in PMN adhesion to both canine carotid arteries and external jugular veins that was two to four times that of control values at 1 mmol/l and declined at higher H2O2 concentrations. Peak retention of PMNs by canine carotid arteries occurred 10 minutes after exposure to 1 mmol/l H2O2 and then rapidly declined to control values; this effect was replicated by a second 20-minute exposure of canine carotid arteries to 1 mmol/l H2O2 60 minutes after the first exposure. Scanning and transmission electron microscopy revealed not only adherence of PMNs to but migration through the vascular endothelium of the carotid artery after H2O2 perfusion. The endothelium was intact in H2O2-treated arteries not exposed to PMNs. H2O2-induced PMN retention was completely inhibited by addition of catalase or the hydroxyl radical scavenger dimethylthiourea to the perfusate by incubation of the PMN with a monoclonal antibody (Mab) against CD18 (R15.7) or by perfusion of the H2O2-treated vessel with CL18/6, a Mab against canine ICAM-1 (intercellular adhesion molecule-1). Similar effects of Mabs on PMN adhesion to H2O2-pretreated cultured endothelium were noted. The retention of PMNs by vessels mechanically denuded of endothelial cells was markedly increased. H2O2 pretreatment of these vessels did not further augment PMN adherence, and no inhibitory effect of R15.7 was noted. Incubation of carotid arteries and PMNs with a specific platelet-activating factor antagonist, WEB2086, completely inhibited the H2O2-induced increased PMN retention by these vessels. CONCLUSIONS. These results indicate that H2O2 in the absence of evidence for permanent endothelial cell injury, can induce a transient, reversible, platelet-activating factor-dependent adherence of PMNs to vessels by mechanisms that depend on an intact endothelium and involve CD18 on the PMN and ICAM-1 on the endothelium.     

Role of P(1) purinergic receptors in myocardial ischemia sensory transduction

OBJECTIVES: To characterize the role that cardiac sensory P(1) purinergic (adenosine A(1) or A(2)) receptors play in transducing myocardial ischemia. METHODS: Porcine nodose ganglion cardiac sensory neuron adenosine A(1) or A(2) receptor function was studied in situ during control states as well as in the presence of the peptides bradykinin and substance P or focal ventricular ischemia. The responses of porcine nodose ganglion cardiac and non-cardiac afferent neuronal somata to adenosine were also studied in vitro. RESULTS: Local application of A(1) or A(2) adenosine receptor agonists modified the activity generated by ventricular sensory neurites associated with 70 and 74% of identified nodose ganglion cardiac afferent somata in situ, respectively, exciting most neurons. In contrast, adenosine reduced the excitability of nodose ganglion cardiac afferent neuronal somata in vitro. Bradykinin and substance P affected 56 and 63%, respectively, of tested afferent neurons. The capacity of ventricular sensory neurites to transduce signals relating to these peptides was virtually eliminated by the presence of P(1) purinergic receptor antagonists. So was their capacity to transduce focal ventricular ischemia. Since most cardiac sensory neurites responded differently to adenosine in vivo than did cardiac afferent neuronal somata in vitro, it appears that the transduction properties of cardiac afferent neurons need to be characterized in situ. CONCLUSIONS: Most ventricular sensory neurites associated with nodose ganglion afferent neurons possess adenosine A(1) and/or A(2) receptors that play a primary role in transducing myocardial ischemic events to central neurons. These data support clinical observations implicating cardiac sensory purinoceptors in transducing myocardial ischemic events.     

Role of interleukin 18 in acute lung inflammation induced by gut ischemia reperfusion

AIM: To study the changes of endogenous interleukin 18 (IL-18) levels and evaluate the role of IL-18 on lung injury following gut ischemia/reperfusion. METHODS: A superior mesenteric artery occlusion model was selected for this research. The mice were randomly divided into four groups: Sham operation (sham), ischemia (0.5 h) followed by different times of reperfusion (I/R), and I/R pretreated with exogenous IL-18 (I/R+IL-18) or IL-18 neutralizing antibody (I/R+IL-18Ab) 15 min before ischemia. Serum IL-18 levels were detected by Western blot and ELISA, and the levels of IL-18 in lung tissue were evaluated by immunohistochemical staining. For the study of pulmonary inflammation, the lung myeloperoxidase (MPO) contents and morphological changes were evaluated. RESULTS: Gut ischemia/reperfusion induced rapid increase of serum IL-18 levels, peaked at 1 h after reperfusion and then declined. The levels of IL-18 in lung tissue were gradually enhanced as the progress of reperfusion. Compared with I/R group, exogenous administration of IL-18 (I/R+IL-18) further remarkably enhanced the pulmonary MPO activity and inflammatory cell infiltration, and in I/R+IL-18Ab group, the content of MPO were significantly reduced and lung inflammation was also decreased. CONCLUSION: Gut ischemia/reperfusion induces the increase of IL-18 expression, which may make IL-18 act as an important proinflammatory cytokine and contribute to gut ischemia/reperfusion-induced lung inflammation.     

Role of interleukin 18 in acute lung inflammation induced by gut ischemia repeifusion

AIM: To study the changes of endogenous interleukin 18 (IL-18) levels and evaluate the role of IL-18 on lung injury following gut ischemia/reperfusion. METHODS: A superior mesenteric artery occlusion model was selected for this research. The mice were randomly divided into four groups: Sham operation (sham), ischemia (0.5 h) followed by different times of reperfusion (I/R), and I/R pretreated with exogenous IL-18 (I/R+IL-18) or IL-18 neutralizing antibody (I/R+IL-18Ab) 15 min before ischemia. Serum IL-18 levels were detected by Western blot and ELISA, and the levels of IL-18 in lung tissue were evaluated by immunohistochemical staining. For the study of pulmonary inflammation, the lung myeloperoxidase (MPO) contents and morphological changes were evaluated. RESULTS: Gut ischemia/reperfusion induced rapid increase of serum IL-18 levels, peaked at 1 h after reperfusion and then declined. The levels of IL-18 in lung tissue were gradually enhanced as the progress of reperfusion. Compared with I/R group, exogenous administration of IL-18 (I/R+IL-18) further remarkably enhanced the pulmonary MPO activity and inflammatory cell infiltration, and in I/R+IL-18Ab group, the content of MPO were significantly reduced and lung inflammation was also decreased. CONCLUSION: Gut ischemia/reperfusion induces the increase of IL-18 expression, which may make IL-18 act as an important proinfiammatory cytokine and contribute to gut ischemia/reperfusion-induced lung inflammation.     

Increased lung permeability following long-term use of free-base cocaine (crack)

The clearance of inhaled 99mTc DTPA aerosol from the lungs is used as an index of lung epithelial permeability. Using the radioaerosol method, we investigated the effects of long-term "crack" (free-base cocaine) inhalation on lung permeability in 23 subjects. Eighteen control subjects (12 nonsmokers and 6 cigarette smokers) with no history of drug use were also studied. Subjects inhaled approximately 150 muCi (approximately 5.6 MBq) of 99mTc DTPA aerosol and quantitative gamma camera images of the lungs were acquired at 1-min increments for 25 minutes. Regions of interest (ROIs) were selected to include the following: (1) both lungs; (2) each individual lung; and (3) the upper, middle, and lower thirds of each lung. 99mTc DTPA lung clearance was determined from the slopes of the respective time-activity plots for the different RIOs. Radioaerosol clearance half-times (T1/2) for the seven nonsmoking crack users (61.5 +/- 18.3 minutes) were longer than for the seven cigarette-smoking crack users (27.9 +/- 16.9 minutes) and nine cigarette-smoking crack plus marijuana users (33.5 +/- 21.6 minutes). T1/2 for the nonsmoking crack users was significantly shorter (p less than 0.001) than for the nonsmoking control group (123.8 +/- 28.7 minutes). T1/2 for the cigarette-smoking drug users was similar to that of the cigarette-smoking control group (33.1 +/- 17.8 minutes), suggesting a similar mechanism of damage from the smoke of crack and tobacco. From these groups, one nonsmoker and 11 cigarette smokers displayed biexponential 99mTc DTPA clearances, indicative of greater lung injury than found in the usual cases of monoexponential clearance. The upper lungs of all crack users groups cleared faster than the lower lungs. The faster and biexponential clearance properties of inhaled 99mTc DTPA aerosol were the principal functional abnormalities found in all the drug users. In contrast, 19 of 23 crack users had normal spirometry and gas exchange. These results indicate that 99mTc DTPA may provide a sensitive and useful assay to evaluate the physiologic effects of cocaine inhalation in the lung.     

Simultaneous mobilization of Mac-1 (CD11b/CD18) and formyl peptide chemoattractant receptors in human neutrophils.

Mobilization of a distinct subset of specific granules provides a physiologically important mechanism to recruit Mac-1 (CD11b/CD18) from an intracellular pool to the external surface of the neutrophil plasma membrane, where the functionally active heterodimer mediates several adherence-dependent processes that are crucial for adequate host defense and cellular inflammatory responses. We observed similar characteristics for translocation of Mac-1 and neutrophil formyl peptide receptors (FPR) and hypothesize that the readily accessible pools of both Mac-1 and FPR are colocalized within this specific granule subset. Plasma membrane levels of both FPR (assessed with 3H-FMLP) and Mac-1 (assessed by fluorescence-activated cell sorter analysis of fluorescein isothiocyanate [FITC]-Mo-1-labeled cells) were markedly downregulated in cells prepared at low temperature from blood cooled to 4 degrees C immediately after removal from the circulation. Levels of both FPR and Mac-1 remained low on cells held at 4 degrees C. Upon warming, spontaneous upregulation of Mac-1 and FPR occurred with similar kinetics and temperature dependency. Translocation of both Mac-1 and FPR was markedly potentiated by exposure of cells to either fluoride ion (which has been shown by others to specifically elicit exocytosis of gelatinase-rich and vitamin B-12 binding protein-poor granules) or granulocyte-macrophage colony-stimulating factor (GM-CSF), a cytokine that markedly potentiates the neutrophils' host defense capabilities. Levels of both FPR and Mac-1 on F-- or GM-CSF-treated neutrophils exceeded those present on cells incubated at 37 degrees C for extended time intervals, indicating that stimulated translocation may involve mobilization of an additional granule subset. Scatchard analysis showed that only low-affinity FPR were translocated during spontaneous and stimulus-dependent upregulation. To directly compare FPR levels on the surface of cells displaying varying levels of Mac-1 within a single cell suspension, cells were labeled with FITC-Mo-1 and sorted into subpopulations based on fluorescence intensity. After sorting, the individual populations were held at 4 degrees C to prevent further spontaneous upregulation, concentrated by centrifugation, and assayed for FPR levels. Under a variety of conditions, FPR levels correlated with Mac-1 (CD11b) expression on cell populations selected on the basis of CD11b fluorescence intensity. Analysis of subcellular fractions obtained from disrupted neutrophils before and after upregulation provided additional support for the hypothesis that Mac-1 and FPR are colocalized within a readily accessible subset of neutrophil granules.(ABSTRACT TRUNCATED AT 400 WORDS)     

Role of shear and leukocyte adherence on venular permeability in the rat mesentery.

The role of fluid shear stress on permeability has been controversial. In vitro studies have shown higher endothelial permeability with an increase in shear, but in vivo higher shear can also decrease permeability by attenuating leukocyte adherence (e.g., during an inflammatory response). The potential contribution of fluid shear and leukocyte adherence acting simultaneously to determine basal levels of permeability remains unresolved. Therefore, the purpose of this study was to understand the effects of basal shear and leukocyte adherence on venular permeability of the rat mesentery. Using a modification of current measurement techniques, we were able to quantify permeability under physiological flow and estimate its convective and diffusive components. We found that water filtration plays a minor role in the transport of albumin across venular endothelium, that permeability exhibits a moderately linear correlation with shear, and that the number of leukocytes adherent to the endothelium accounts for the majority of the scatter in this correlation. Multiple regression analysis of permeability as a function of shear rate and leukocyte adherence revealed significant roles for both factors (regression P < 0.01, r2 = 73.9%).     

Role of alpha4 integrin and VCAM-1 in CD18-independent neutrophil migration across mouse cardiac endothelium

Myocardial damage due to reperfusion of ischemic tissue is caused primarily by infiltrating neutrophils. Although leukocyte beta2 integrins (CD18) play a critical role, significant neutrophil emigration persists when CD18 is neutralized or absent. This study examined the role of leukocyte beta1 integrin (alpha4) and its endothelial ligand VCAM-1 in CD18-independent neutrophil migration across cardiac endothelium. In a mouse model of myocardial ischemia and reperfusion, we show that compared with wild-type mice, neutrophil infiltration efficiency was reduced by 50% in CD18-null mice; in both types of mice, myocardial VCAM-1 staining increased after reperfusion. In wild-type mice, antibodies against CD18, ICAM-1 (an endothelial ligand for CD18), or VCAM-1 given 30 minutes before ischemia did not block neutrophil emigration at 3 hours reperfusion. Although anti-VCAM-1 attenuated neutrophil emigration by 90% in CD18-null mice, it did not diminish myocardial injury. To determine if CD18-independent neutrophil emigration was a tissue-specific response, we used isolated peripheral blood neutrophils from wild-type or CD18-null mice and showed neutrophil migration across lipopolysaccharide-activated cultured cardiac endothelium is CD18-independent, whereas migration across endothelium obtained from inferior vena cava is CD18-dependent. Consistent with our in vivo findings, migration of CD18-deficient neutrophils on cardiac endothelial monolayers is blocked by antibodies against alpha4 integrin or VCAM-1. We conclude tissue-specific differences in endothelial cells account, at least partially, for CD18-independent neutrophil infiltration in the heart.     

Mac-1 (CD11b/CD18) is essential for Fc receptor-mediated neutrophil cytotoxicity and immunologic synapse formation

Receptors for human immunoglobulin (Ig)G and IgA initiate potent cytolysis of antibody (Ab)-coated targets by polymorphonuclear leukocytes (PMNs). Mac-1 (complement receptor type 3, CD11b/CD18) has previously been implicated in receptor cooperation with Fc receptors (FcRs). The role of Mac-1 in FcR-mediated lysis of tumor cells was characterized by studying normal human PMNs, Mac-1-deficient mouse PMNs, and mouse PMNs transgenic for human FcR. All PMNs efficiently phagocytosed Ab-coated particles. However, antibody-dependent cellular cytotoxicity (ADCC) was abrogated in Mac-1(-/-) PMNs and in human PMNs blocked with anti-Mac-1 monoclonal Ab (mAb). Mac-1(-/-) PMNs were unable to spread on Ab-opsonized target cells and other Ab-coated surfaces. Confocal laser scanning and electron microscopy revealed a striking difference in immunologic synapse formation between Mac-1(-/-) and wild-type PMNs. Also, respiratory burst activity could be measured outside membrane-enclosed compartments by using Mac-1(-/-) PMNs bound to Ab-coated tumor cells, in contrast to wild-type PMNs. In summary, these data document an absolute requirement of Mac-1 for FcR-mediated PMN cytotoxicity toward tumor targets. Mac-1(-/-) PMNs exhibit defective spreading on Ab-coated targets, impaired formation of immunologic synapses, and absent tumor cytolysis.     

Impaired transendothelial migration by neonatal neutrophils: abnormalities of Mac-1 (CD11b/CD18)-dependent adherence reactions

In order to evaluate the functions of lymphocyte function antigen-1 (LFA-1) (CD11a/CD18) and Mac-1 (CD11b/CD18) on neonatal neutrophils, we examined neutrophil adhesion to and migration through human umbilical vein endothelial cell (HUVEC) monolayers in vitro. Transendothelial migration of adult neutrophils was greatly enhanced by preincubation of HUVEC with interleukin-1 (IL-1). This migration was significantly inhibited by monoclonal antibodies (MoAbs) against LFA-1 (CD11a) and Mac-1 (CD11b) subunits. Migration of neonatal neutrophils was markedly diminished compared to adult neutrophils, and MoAbs against LFA-1 further reduced migration. In contrast, anti-Mac-1 MoAb was not inhibitory. Adhesion of adult neutrophils was significantly enhanced by prestimulation of HUVEC with IL-1, and was significantly inhibited by MoAbs against LFA-1. Adhesion of neonatal neutrophils was near adult levels and comparably inhibited by anti-LFA-1 MoAb. In addition, adhesion of neonatal and adult neutrophils to purified ICAM-1 in artificial planar membranes was comparable and almost completely inhibited by anti-LFA-1 MoAb. Chemotactic stimulation induced Mac-1-dependent adhesion of adult neutrophils to endothelial cells, purified intercellular adherence molecule-1 (ICAM-1) and protein-coated glass. In marked contrast, adhesion of neonatal neutrophils to these substrates was not significantly increased by chemotactic stimulation. These findings indicate that diminished transendothelial migration by neonatal neutrophils is related to abnormal interactions of Mac-1 with ICAM-1 and possibly other endothelial ligands. These functional deficits may contribute to impaired inflammation and infectious susceptibility in human neonates.     

Role of CCK(A) receptors in postprandial lower esophageal sphincter function in morbidly obese subjects

To reduce weight, some morbidly obese patients are treated with an intragastric balloon, often resulting in increased reflux symptoms. As transient lower esophageal sphincter relaxations (TLESRs) are the major mechanism underlying reflux and can be reduced by cholecystokinin-A (CCK_A) blockade, we hypothesized that the CCK_A-receptor antagonist loxiglumide could reduce gastroesophageal reflux in these subjects. Postprandial manometric studies were performed in 12 obese subjects during infusion of placebo or loxiglumide. Before balloon placement, loxiglumide did not significantly reduce the rate of TLESRs but attenuated the postprandial decrease in LES pressure. After 10 weeks of balloon treatment, loxiglumide significantly reduced the rate of TLESRs. Postprandial LES pressure was significantly increased, whereas the meal-induced decrease in LES pressure was absent. Neither loxiglumide nor balloon placement affected gastroesophageal reflux. In conclusion, CCK_A receptors play an important role in post-prandial LES pressure decrease and are involved in the reflex pathway underlying the triggering of TLESRs, at least after balloon placement.     

PGE(1) short term therapy in critical lower limb ischemia.

AIM: Our study aims to evaluate the efficiency of short-term therapy with alprostadil (a PGE molecular derivative) on patients affected by critical ischemia of the lower limbs and unsuitable for surgical revascularization. The study was carried out on two groups of patients treated with the traditional long-term or a short-term protocol respectively. METHODS: The parameters evaluated and statistically compared to existing studies were, the side effects, subjective pain measured on an analogic scale, objective pain calculated according to analgesic intake, and change in trophic lesions. RESULTS: Our results revealed some differences between the two groups. The manifestation of side effects led to treatment suspension in 8% of long-term therapy cases only. Subjective pain was reduced or disappeared in 83.83% of cases (p<0.001) and there was no statistically significant difference between the two groups. The course of analgesic intake was again similar in both groups. Trophic lesions improved or completely healed in 64.7% (p<0.005) and although a greater tendency towards complete healing was evident in the short-term patients, it was not statistically significant. There was no significant difference between the two groups in the ankle/arm pressure index, but a significant improvement has been observed in 30.88% of cases. The results we obtained from both groups are similar and confirm the valid therapeutic use of alprostadil in patients with peripheral arterial occlusive disease (PAOD). CONCLUSION: Our study reveals the presence of intrinsic advantages to the physician with the short-term schedule, through its higher tolerability, improved and more frequent patient and therapy controls and shorter hospitalization.     

Monoclonal antibodies to leukocyte integrins CD11a/CD18 and CD11b/CD18 or intercellular adhesion molecule-1 inhibit chemoattractant-stimulated neutrophil transendothelial migration in vitro.

Intercellular adhesion molecule-1 (ICAM-1) is present on the endothelium and binds to one or more members of the CD11/CD18 family of leukocyte surface integrins. To assess the role of these molecules in mediating chemotaxis of neutrophils across the endothelium, an in vitro model consisting of monolayers of human umbilical vein endothelial cells (HUVEC) grown on amniotic connective tissue was used. Neutrophils placed on the apical sides of these cultures migrated across the endothelium in response to chemoattractants added basally. Monoclonal antibodies (MoAbs) to CD11a, CD11b, and CD18 on the neutrophils inhibited this migration by 52% +/- 11%, 29% +/- 19%, and 90% +/- 7%, respectively. An MoAb to ICAM-1 inhibited transendothelial chemotaxis of the leukocytes by 55% +/- 16%. Inhibition was mediated by binding of the MoAb to ICAM-1 on the HUVEC, rather than by any direct effect of the antibody on the neutrophils. When used in combination, MoAbs to CD11a and to CD11b inhibited migration in a nearly additive fashion. A similar additive effect was observed when MoAbs to CD11b and to ICAM-1 were used together. In contrast, MoAbs to CD11a and to ICAM-1 produced no more inhibition when used in combination than when added singly. These results show that ICAM-1, CD11a/CD18, and CD11b/CD18 all participate in controlling migration of neutrophils across endothelial monolayers in response to chemotactic agents.     

Identification of autoantibodies specific for the neutrophil adhesion glycoproteins CD11b/CD18 in patients with autoimmune neutropenia.

Anti-neutrophil antibodies have been described in a variety of clinical conditions associated with neutropenia. However, relatively little is known about the antigenic specificities of naturally occurring anti-neutrophil autoantibodies. We investigated the possibility that anti-neutrophil antibodies specific for the neutrophil adhesion glycoprotein (GP) complex CD11b/CD18 might be present in the sera of some patients with autoimmune neutropenia. These membrane GPs have been shown to be highly immunogenic in the production of murine monoclonal antibodies against neutrophil antigens. Moreover, autoantibodies to the platelet membrane GP complex IIb/IIIa, another member of the integrin family of cell adhesion proteins, have been demonstrated in immune thrombocytopenic purpura. Sera from 50 patients known to have anti-neutrophil IgG antibodies were evaluated using an immunobead "antigen capture" assay, modeled after a method used to identify anti-platelet GPIIb/IIIa autoantibodies. This assay detected anti-CD11b/CD18 autoantibodies in seven of the 50 sera. Each of these seven sera demonstrated decreased IgG binding to the neutrophils of a patient with congenital deficiency of CD11b/CD18. The patient with the highest levels of anti-CD11b/CD18 suffered recurrent skin infections and cellulitis, and died of respiratory failure during one of multiple episodes of pneumonia. Purified IgGs from five of these patients demonstrated effects on adhesion and/or opsonin receptor-mediated functions when tested with intact neutrophils in vitro. Our findings indicate that some patients with autoimmune neutropenia have autoantibodies specific for the functionally important neutrophil adhesion proteins CD11b/CD18. Our findings also raise the possibility that these autoantibodies may, in some cases, interfere with neutrophil function, thereby amplifying the risk of infection associated with neutropenia.     

Role of microtubules in granulocyte adherence.

The adherence of human polymorphonuclear leukocytes (PMN) to nylon fibers is inhibited in a dose-dependent fashion by exposure in vitro of these cells to either colchicine or VM-26, both of which agents prevent microtubule assembly. Mean adherence of human PMN was 48% +/- 2%, following treatment with 10(-5) M colchicine or 10(-4) M VM-26 it was reduced to 31% +/- 2% and 7%, respectively. Peritoneal PMN obtained from mice and mink with Chediak-Higashi syndrome (CHS) thought to have a microtubule-membrane disorder affecting the PMN had a mean adherence of 29% +/- 3% and 40% +/- 8% compared to control values of 46% +/- 5% and 73% +/- 8%, respectively, from the mice and mink. Both ascorbic acid and bethanechol, shown previously to enhance microtubule assembly in humans with CHS, normalized granulocyte adherence in PMN obtained from mice with CHS. Cyclic nucleotide levels were not altered by treatment of human PMN with colchicine, nor did they differ between normal and CHS animals. Thus it appears that the state of microtubule assembly may directly affect the properties of the PMN plasma membrane without requiring alterations of cyclic nucleotides as an intermediary.     

Increased adherence of monocytes to fibronectin in bronchiectasis. Regulatory effects of bacterial lipopolysaccharide and role of CD11/CD18 integrins.

Regulated adherence of monocytes to extracellular matrix is a prerequisite for accumulation of mononuclear phagocytes during pulmonary infection and inflammation. We have obtained monocytes from patients with an inflammatory lung disease (bronchiectasis) and from control subjects and have compared their adherence to fibronectin. Spontaneous adherence of monocytes from the control subjects was 20 +/- 2%, whereas that of patients' cells was markedly higher and correlated with the severity of airway inflammation: 65 +/- 5% and 40 +/- 8% in patients with purulent and mucoid sputum, respectively. Endotoxin and cytokines from areas of airway disease are likely to be responsible for the observed monocyte activation, since: (1) endotoxin was detectable in all of the patients but in none of the control subjects; (2) LPS produced a dose-related increase in adherence of normal monocytes in vitro (maximal 65 +/- 2% adherence at 1 microgram/ml of LPS); (3) recombinant cytokines and LPS produced additive effects on monocyte adherence in vitro. The adherence of the patients' monocytes to fibronectin was substantially mediated by CD11/CD18 integrins, via both RGD-dependent and RGD-independent mechanisms. These data indicate that signals arising from foci of infection and inflammation can influence the adherence of monocytes, and they are likely to be determinants of the accumulation of mononuclear phagocytes in the lungs of patients with bronchiectasis.     

中性粒细胞胞外诱捕网在系统性红斑狼疮相关间质性肺病中的作用

中性粒细胞参与病原体清除与早期炎症反应,是免疫系统的重要组成部分。但近年来越来越多的研究表明,中性粒细胞通过形成中性粒细胞胞外诱捕网(NETs)介导炎症反应并促进纤维化的形成,在自身免疫性疾病和间质性肺病(ILD)的发病机制中的作用逐渐受到重视。本文首先介绍NETs的结构、功能和形成过程,并结合NETs在其他自身免疫病中的作用,总结NETs参与系统性红斑狼疮(SLE)相关ILD针对NETs的发病机制,最后提出了自身免疫性疾病相关ILD针对NETs的潜在治疗靶点。