Inhibition Of ICAM-1 Research Articles

Dimethyl malonate protects the lung in a murine model of acute respiratory distress syndrome.

Succinate is a proinflammatory citric acid cycle metabolite that accumulates in tissues during pathophysiological states. Oxidation of succinate after ischemia-reperfusion leads to reversal of the electron transport chain and generation of reactive oxygen species. Dimethyl malonate (DMM) is a competitive inhibitor of succinate dehydrogenase, which has been shown to reduce succinate accumulation. We hypothesized that DMM would protect against inflammation in a murine model of ARDS. C57BL/6 mice were given ARDS via 67.7 μg of intratracheally administered lipopolysaccharide. Dimethyl malonate (50 mg/kg) was administered via tail vein injection 30 minutes after injury, then daily for 3 days. The animals were sacrificed on day 4 after bronchoalveolar lavage (BAL). Bronchoalveolar lavage cell counts were performed to examine cellular influx. Supernatant protein was quantified via Bradford protein assay. Animals receiving DMM (n = 8) were compared with those receiving sham injection (n = 8). Cells were fixed and stained with FITC-labeled wheat germ agglutinin to quantify the endothelial glycocalyx (EGX). Total cell counts in BAL was less for animals receiving DMM (6.93 × 10 6 vs. 2.46 × 10 6 , p = 0.04). The DMM group had less BAL macrophages (168.6 vs. 85.1, p = 0.04) and lymphocytes (527.7 vs. 248.3; p = 0.04). Dimethyl malonate-treated animals had less protein leak in BAL than sham treated (1.48 vs. 1.15 μg/μl, p = 0.03). Treatment with DMM resulted in greater staining intensity of the EGX in the lung when compared with sham (12,016 vs. 15,186 arbitrary units, p = 0.03). Untreated animals had a greater degree of weight loss than treated animals (3.7% vs. 1.1%, p = 0.04). Dimethyl malonate prevented the upregulation of monocyte chemoattractant protein-1 (1.66 vs. 0.92 RE, p = 0.02) and ICAM-1 (1.40 vs. 1.01 RE, p = 0.05). Dimethyl malonate reduces lung inflammation and capillary leak in ARDS. This may be mediated by protection of the EGX and inhibition of monocyte chemoattractant protein-1 and ICAM-1. Dimethyl malonate may be a novel therapeutic for ARDS.

The interrupted cross-talk of inflammatory and oxidative stress trajectories signifies the effect of artesunate against hepatic ischemia/reperfusion-induced inflammasomopathy

The antimalarial drug artesunate (Art) has proven its beneficial effects against ischemia/reperfusion (I/R) injury in diverse organs, but its potential role against hepatic I/R is still obscure. This study, hence, examined whether treatment with Art alone or in combination with rapamycin (Rapa), an mTOR inhibitor, can ameliorate hepatic I/R injury via targeting the NLRP3 inflammasome signaling pathway. Rats were divided into hepatic sham- and I/R-operated rats. The latter were either left untreated (I/R group) or treated with Art, Rapa, or their combination. On the molecular level, all treatment regimens succeeded to hinder inflammasome assembly and activation, assessed as NLRP3, ASC, cleaved caspase-1, caspase-11, N-terminal cleaved gasdermin-D (GSDMD-N), IL-1β, and IL-18. This effect was associated by the inhibition in the harmful signaling pathways HMGB1/RAGE and TLR4/MyD88/TRAF6 to inactivate the transcription factor NF-κB and the production of its pro-inflammatory cytokines IL-1β, IL-18, IL-6, and TNF-α. Additionally, this effect entailed the inhibition of ICAM-1/MPO/ROS cascade, which in turn hampered cell demise induced by apoptosis, manifested as correction of the imbalanced Bcl2/Bax, as well as pyroptosis (LDH, cleaved caspase-1, caspase-11, GSDMD-N, IL-1β, and IL-18), and necrosis. The corrected pathways were reflected on the improved liver function (serum ALT, AST, and LDH) and microscopical hepatic architecture. Noteworthy, the effect of Art on all parameters exceeded significantly that of Rapa and even improved the effect of the latter in the combination group. In conclusion, our results suggest novel roles for Art in abating functional and structural I/R-induced hepatic abnormalities via several traversing cross-talking pathways that succeeded to abate NLRP3 inflammasome and cell death.

Interaction between ICAM1 in endothelial cells and LFA1 in T cells during the pathogenesis of experimental Parkinson's disease.

Parkinson's disease (PD) is a chronic progressive disease that affects the central nervous system with a variety of symptoms. Although the precise etiology of PD is not yet fully understood, there is evidence to suggest that T cells serve an important role in the pathogenesis of PD. However, how T cells are recruited in the brain tissue remains to be elucidated. The present study utilized human samples from patients with and without PD to investigate the infiltration of T cells in lesions in the central nervous system. A chemically-induced mouse PD model was also used to investigate the roles of T cells in the pathogenesis of PD. Depletion of CD4+ or CD8+ T cells was achieved using neutralizing antibodies. Adhesion molecule levels were assessed by flow cytometry. The results of the study indicated that T cell infiltration was evident in both human and murine samples of PD. Blocking CD4+ or CD8+ T cells attenuated the severity of murine PD. Intercellular adhesion molecule 1 (ICAM1 or CD54) was upregulated in mouse PD compared with controls, and its receptor, lymphocyte function-associated antigen-1 (LFA1) was overexpressed in T cells of the brain in PD mice compared with controls. Furthermore, inhibition of ICAM1 or LFA1 attenuated PD-associated characteristics in mice. In conclusion, the interaction between ICAM1 and LFA1 plays a role in recruiting T cells to the central nervous system to mediate experimental PD.

Pengaruh Crude Fukoidan dari Ekstrak Sargassum crassifolium terhadap Kadar ICAM-1 dan VCAM-1 pada Sel Raw 264.7 yang Diinduksi Lipopolisakarida

Inflamasi adalah respon jaringan pembuluh darah terhadap infeksi dan jaringan yang rusak untuk menghilangkan penyebab inflamasi. Tapi dalam beberapa kondisi, inflamasi dapat menyebabkan timbulnya penyakit kronis, seperti aterosklerosis. Adesi leukosit ke endotelium vaskular merupakan ciri proses inflamasi Adanya molekul adesi, seperti ICAM-1dan VCAM-1 yang meningkat dapat menyebabkan adesi monosit dan limfosit pada sel endotel melalui ikatan molekul adesi pada sel endotel. Crude fukoidan berasal dari Sargassum crassifolium yang diambil dari perairan Garut dan diekstraksi dengan HCl encer, diuji aktivitas antiinflamasi melalui penghambatan kadar ICAM-1 dan VCAM-1 menggunakan model sel RAW 264.7 yang diinduksi inflamasi dengan lipopolisakarida. Uji viabilitas dilakukan dengan metode MTT pada rentang konsentrasi 0,49-1000 µg/mL. Pola penghambatan proliferasi sel dipengaruhi oleh konsentrasi. Dari uji viabilitas didapat konsentrasi tertinggi yang menyebabkan viabilitas sel sebesar 80% adalah konsentrasi crude fukoidan 86,46 μg/ml. Crude fukoidan terbukti dapat menurunkan kadar ICAM-1 dan VCAM-1 pada konsentrasi 50 dan 25 μg/ml. Persen penghambatan kadar ICAM pada konsentrasi 50 µg/mL adalah 61,04% dibanding kontrol inflamasi dan 74,26% pada konsentrasi 25 µg/mL. Sementara persen penghamabatan kadar VCAM-1 pada konsentrasi 50 µg/mL adalah74,76% dibanding kontrol inflamasi dan 79,94% pada konsentrasi 25 µg/mL.

TAK-733 inhibits inflammatory neointimal formation by suppressing proliferation, migration, and inflammation in vitro and in vivo

As a potent and selective allosteric inhibitor of MEK, TAK-733 has been shown to exert anti-cancer effects for a wide range of cancers both in vitro and in vivo. However, its effects on inhibiting growth have never been investigated in the cardiovascular system, where regulation of abnormal vascular smooth muscle cell growth in neointimal hyperplasia is an important area of focus. Angiotensin II was used to mimic inflammatory neointimal hyperplasia in an in vitro environment, and balloon catheter-induced injury with an infusion of angiotensin II was used to generate an in vivo rat restenosis model under inflammatory conditions. TAK-733 exerted anti-proliferative and anti-migratory effects on human vascular smooth muscle cells. These multiple effects of TAK-733 were evaluated using various assays, such as cell cycle analysis and wound healing. Interestingly, TAK-733 did not induce apoptosis in smooth muscle cells but only reduced the proliferation rate; additionally, it did not affect EC viability. TAK-733 also exhibited anti-inflammatory activity, as observed by attenuated monocyte adhesion to smooth muscle cells via inhibition of ICAM1 and VCAM1 overexpression. The in vivo study demonstrated that neointimal hyperplasia after balloon injury and angiotensin II stimulation was suppressed by TAK-733, and downregulation of the inflammatory signal and enhanced re-endothelialization were observed. TAK-733 may have therapeutic potential for treating neointimal hyperplasia by attenuating smooth muscle cell proliferation, migration, and inflammation. Thus, TAK-733 could be a promising drug candidate for treating patients with restenosis.

ICAM-1null C57BL/6 Mice Are Not Protected from Experimental Ischemic Stroke.

Accumulation of neutrophils in the brain is a hallmark of cerebral ischemia and considered central in exacerbating tissue injury. Intercellular adhesion molecule (ICAM)-1 is upregulated on brain endothelial cells after ischemic stroke and considered pivotal in neutrophil recruitment as ICAM-1-deficient mouse lines were found protected from experimental stroke. Translation of therapeutic inhibition of ICAM-1 into the clinic however failed. This prompted us to investigate stroke pathogenesis in Icam1tm1Alb C57BL/6 mutants, a true ICAM-1null mouse line. Performing transient middle cerebral artery occlusion, we found that absence of ICAM-1 did not ameliorate stroke pathology at acute time points after reperfusion. Near-infrared imaging showed comparable accumulation of neutrophils in the ischemic hemispheres of ICAM-1null and wild type C57BL/6 mice. We also isolated equal numbers of neutrophils from the ischemic brains of ICAM-1null and wild type C57BL/6 mice. Immunostaining of the brains showed neutrophils to equally accumulate in the leptomeninges and brain parenchymal vessels of ICAM-1null and wild type C57BL/6 mice. In addition, the lesion size was comparable in ICAM-1null and wild type mice. Our study demonstrates that absence of ICAM-1 neither inhibits cerebral ischemia-induced accumulation of neutrophils in the brain nor provides protection from ischemic stroke.

The anti-atherosclerotic effect of Prosopis Farcta is associated with the inhibition of VCAM-1 and ICAM-1

The anti-atherosclerotic effect of Prosopis Farcta is associated with the inhibition of VCAM-1 and ICAM-1

Curcumin prevents reperfusion injury following ischemic stroke in rats via inhibition of NF‑κB, ICAM-1, MMP-9 and caspase-3 expression.

Reperfusion is the only approved therapy for acute ischemic stroke; however, it can cause excessive inflammation responses and aggravate brain damage. Therefore, supplementary treatment against inflammation caused by reperfusion is required. In a previous study from our group, curcumin was demonstrated to decrease infarction volume, brain edema and blood-brain barrier (BBB) disruption against cerebral ischemia/reperfusion (I/R) injury. However, the underlying mechanisms remain unclear. The present study was conducted to understand whether curcumin protects against cerebral I/R injury through anti-inflammatory and antiapoptotic properties. Ischemia for 1 h was induced in vivo in Wistar rats by middle cerebral artery occlusion (MCAO), followed by reperfusion for 24 h, and curcumin was injected intraperitoneally at 30 min prior to reperfusion. Immunohistochemistry was performed to analyze the expression levels of nuclear factor (NF)-κB, intercellular adhesion molecule (ICAM)-1, matrix metalloproteinase (MMP)-9 and caspase-3. The findings revealed that inflammation (NF-κB, ICAM-1 and MMP-9) and apoptosis (caspase-3)-related markers were significantly downregulated in the curcumin-treated MCAO group compared with the vehicle-treated MCAO group. Furthermore, brain infarction size, brain edema and neurological dysfunction were attenuated in the curcumin-treated MCAO group compared with the vehicle-treated MCAO group. Taken together, the present results provided evidence that the protective effect of curcumin against cerebral I/R injury might be mediated by anti-inflammatory and anti-apoptotic properties. Therefore, curcumin may be a promising supplementary agent against cerebral I/R injury in the future.

Digested protein isolate from fresh and stored Carioca beans reduced markers of atherosclerosis in oxidized LDL-induced THP-1 macrophages

Oxidized LDL (ox-LDL) and its interaction with lectin type ox-LDL receptor (LOX-1) determine atherosclerosis progression. The potential of peptides from digested protein isolate (DPI) derived from fresh and stored Carioca bean (Phaseolus vulgaris L.) to prevent ox-LDL induced inflammation in human THP-1 macrophage-like cells was examined here. BRS Pontal (PO) and BRSMG Madreperola (MP) fresh and stored for 6 months were cooked, and protein isolates were digested by pepsin–pancreatin. Peptides from stored Carioca beans decreased prostaglandin E-2 (PGE-2) (from 17.7 to 47%) and tumour necrosis factor-α (TNF-α) (12.3 to 82%). Stored MP (0.01 mg/mL) inhibited reactive oxygen species (ROS). LOX-1 and matrix metalloproteinase-9 (MMP-9) expression were reduced by peptides from all beans. Stored PO and MP digested protein isolates reduced expression of 10 cytokines related to atherosclerosis process. Peptides from Carioca beans presented anti-atherosclerotic properties comparable to simvastatin, which were related to inhibition of LOX-1, MMP-9 and ICAM-1.

Monascus Adlay and Monacolin K Attenuates Arterial Thrombosis in Rats through the Inhibition of ICAM-1 and Oxidative Stress

Background/Aims: Monascus Adlay (MA) prepared from fungal fermentation of Monascus purpureus inoculating with cooked adlay contains high content of monakolin K (MK) and phenolic compounds. We explored whether MA and MK improve FeCl₃-induced arterial thrombosis in rats. Methods: The rats were divided into control, FeCl₃-treated rat carotid artery occlusion (TTO), TTO determined with one-week MA, and TTO determined with one-week MK. We compared MA or MK effects on oxidative stress by chemiluminescence amplification and immunohistochemistry, TTO by a transonic system, NFκB, ICAM-1, endoplasmic reticulum stress CHOP and Nrf2 signaling by western blotting. Results: MA or MK efficiently depressed O₂^-, H₂O₂ and HOCl levels, platelet activation and aggregation and H₂O₂-enhanced ICAM-1 and VCAM-1 expression in the endothelial cells. FeCl₃ significantly increased NFκB p65, 3-nitrotyrosine, CHOP and ICAM-1 expression, and decreased nuclear Nrf2 translocation and induces arterial thrombus formation. MA or MK pretreatment significantly elongated the level of FeCl₃-induced TTO compared to TTO group, significantly decreased proinflammatory NF-κB/ICAM-1 signaling, endoplasmic reticulum stress CHOP expression and decreased thrombotic area. MA or MK significantly preserved nuclear Nrf2 translocation. MA and MK exerted a similar protective effect in attenuating thrombus formation. Conclusions: We suggest MA is better than MK to improve FeCl₃-induced arterial thrombosis.

Stroke‐associated inflammation: is von Willebrand factor a ‘bad guy’?

Stroke‐associated inflammation: is von Willebrand factor a ‘bad guy’?

Endogenous Regulatory T Cells Adhere in Inflamed Dermal Vessels via ICAM-1: Association with Regulation of Effector Leukocyte Adhesion

Regulatory T cells (Tregs) must express appropriate skin-homing adhesion molecules to exert suppressive effects on dermal inflammation. However, the mechanisms whereby they control local inflammation remain unclear. In this study we used confocal intravital microscopy in wild-type and Foxp3-GFP mice to examine adhesion of effector T cells and Tregs in dermal venules. These experiments examined a two-challenge model of contact sensitivity (CS) in which Treg abundance in the skin progressively increases during the course of the response. Adhesion of CD4(+) T cells increased during CS, peaking 8-24 h after an initial hapten challenge, and within 4 h of a second challenge. At these time points, 40% of adherent CD4(+) T cells were Foxp3(+) Tregs. CD4(+) T cell adhesion was highly dependent on ICAM-1, and consistent with this finding, anti-ICAM-1 prevented Treg adhesion. Skin TGF-β levels were elevated in skin during both challenges, in parallel with Treg adhesion. In the two-challenge CS model, inhibition of ICAM-1 eliminated Treg adhesion, an effect associated with a significant increase in neutrophil adhesion. Similarly, total CD4(+) T cell depletion caused an increase in adhesion of CD8(+) T cells. Because Treg adhesion was restricted by both of these treatments, these experiments suggest that adherent Tregs can control adhesion of proinflammatory leukocytes in vivo. Moreover, the critical role of ICAM-1 in Treg adhesion provides a potential explanation for the exacerbation of inflammation reported in some studies of ICAM-1-deficient mice.

Role of α4 Integrin (CD49d) in the Pathogenesis of Diabetic Retinopathy

The pathophysiology of diabetic retinopathy is mediated by leukocyte adhesion to the vascular endothelium of the diabetic retina, which results in endothelial injury, blood-retina barrier breakdown, and capillary nonperfusion. Leukocyte adhesion is triggered by the interaction of vascular endothelium adhesion molecules, such as ICAM-1, with leukocyte integrins, such as CD18. Inhibition of ICAM-1/CD18 signaling suppresses but does not completely abolish the cardinal manifestations of diabetic retinopathy, suggesting a role for additional adhesion molecules. Integrin alpha 4 (CD49d), in complex with integrin beta1, forms very late antigen-4 (VLA-4), which interacts with vascular cell adhesion molecule-1. The authors have now studied the role of integrin alpha 4/CD49d in the pathogenesis of diabetic retinopathy. Diabetes mellitus was induced in Long Evans rats with streptozotocin, and an anti-alpha 4 integrin/CD49d neutralizing antibody was injected 5 and 10 days later. Two weeks after streptozotocin administration, vascular leakage was quantified with the Evans Blue technique. Leukostasis was measured with a static adhesion assay ex vivo and the FITC-lectin perfusion method in vivo. Retinal VEGF and TNF-alpha levels and NF-kappaB activity were measured by ELISA. Blockade of alpha 4 integrin/CD49d attenuated the diabetes-induced upregulation of NF-kappaB activation, VEGF, and TNF-alpha protein levels and reduced significantly diabetes-induced leukocyte adhesion and vascular leakage. These data identify alpha 4 integrin/CD49d as a mediator of leukocyte adhesion and the resultant early signature abnormalities of diabetic retinopathy. Inhibition of this signaling pathway may hold promise for clinical activity in patients with diabetes.

Cross-Talk between ICAM-1 and GM-CSF Receptor Signaling Modulates Eosinophil Survival and Activation

Reversal of eosinophilic inflammation has been an elusive therapeutic goal in the management of asthma pathogenesis. In this regard, GM-CSF is a primary candidate cytokine regulating eosinophil activation and survival in the lung; however, its molecular mechanism of propagation and maintenance of stimulated eosinophil activation is not well understood. In this study, we elucidate those late interactions occurring between the GM-CSF receptor and activated eosinophil signaling molecules. Using coimmunoprecipitation with GM-CSF-stimulated eosinophils, we have identified that the GM-CSF receptor beta-chain (GMRbeta) interacted with ICAM-1 and Shp2 phosphatase, as well as Slp76 and ADAP adaptor proteins. Separate experiments using affinity binding with a tyrosine-phosphorylated peptide containing an ITIM (ICAM-1 residues 480-488) showed binding to Shp2 phosphatase and GMRbeta. However, the interaction of GMRbeta with the phosphorylated ICAM-1-derived peptide was observed only with stimulated eosinophil lysates, suggesting that the interaction of GMRbeta with ICAM-1 required phosphorylated Shp2 and/or phosphorylated GMRbeta. Importantly, we found that inhibition of ICAM-1 in activated eosinophils blocked GM-CSF-induced expression of c-fos, c-myc, IL-8, and TNF-alpha. Moreover, inhibition of ICAM-1 expression with either antisense oligonucleotide or an ICAM-1-blocking Ab effectively inhibited ERK activation and eosinophil survival. We concluded that the interaction between ICAM-1 and the GM-CSF receptor was essential for GM-CSF-induced eosinophil activation and survival. Taken together, these results provide novel mechanistic insights defining the interaction between ICAM-1 and the GM-CSF receptor and highlight the importance of targeting ICAM-1 and GM-CSF/IL-5/IL-3 receptor systems as a therapeutic strategy to counter eosinophilia in asthma.

Nutlin-3 inhibits the NFκB Pathway in a p53 Dependent Manner: Implications in Lung Cancer Therapy

Nutlins were identified as the first potent and specific small molecule Mdm2 antagonists that inhibit the p53- Mdm2 interaction. We show in this study that Nutlin-3 can downregulate TNFα induced activation of the NF-κB reporter in lung cancer cells. Activation of p53 dependent transcription is not compromised when Nutlin-3 is combined with TNFα. Instead, this combination treatment decreases cell viability in a p53 dependent manner. We show that Nutlin-3 strikingly inhibits the protein expression of NF-κB target genes ICAM-1 and MCP-1 while other targets like Bcl-xL and FLIP are not affected, thereby suggesting that the inhibition is promoter specific. This inhibition of ICAM-1 and MCP-1 by Nutlin-3 is again dependent on the p53 status in cells. Furthermore, we show that Nutlin-3 strongly inhibits protein expression of ICAM-1 and MCP-1 induced by IL1, another NF-κB activating stimuli. Nutlin-3 does not inhibit Akt phosphorylation, IκBα phosphorylation, IκBα degradation, p65 modification or p65 DNA binding in the cell lines tested. This study suggests the potential of Nutlin-3 as a bitargeted anti-cancer drug by simultaneously causing p53 activation and NF-κB suppression. It also suggests that Nutlin-3 could be evaluated for treatment of lung cancer as a single agent or in combination therapy by targeting its effect on ICAM-1 and MCP-1 which are known to be critical for cancer cell invasion, thereby downregulating tumor formation and metastasis. This study also suggests biomarkers of response for evaluation of Nutlin-3 in the clinic.

The Effect of Tetomilast (OPC-6535) on Cultured Human Vascular Endothelial Cells

Purpose: Tetomilast is currently in clinical development for the treatment of inflammatory bowel disease and chronic obstructive pulmonary disease. Leukocyte adhesion to endothelium and transmigration into the damaged tissue are essential features of the inflammatory process; endothelial permeability and adhesion molecule expression are increased with inflammation. Although the mechanism of action for tetomilast has not been fully elucidated, tetomilast is known to inhibit phosphodiesterase 4 (PDE4). To investigate the mechanisms involved in tetomilast's anti-inflammatory action, we used primary vascular endothelial cells (EC) to study its effect on cell monolayer permeability and adhesion molecule expression, as compared with that of PDE4-selective inhibitors. Methods: Human umbilical vein EC (HUVEC) were cultured on a membrane insert. The permeability increase was induced by incubation with thrombin (0.2 unit/mL) or histamine (10 μM) at 37°C for 1 hr and quantified by the detection of diffused FITC-dextran through the HUVEC monolayer. For the study of adhesion molecule expression, a cell-based ELISA was used to measure VCAM-1, ICAM-1, and E-selectin expression in HUVEC and human lung microvessel EC (HLMVEC) following TNF-αα stimulation. Results: Tetomilast (20 μM) inhibited thrombin- or histamine-induced permeability increase by 29.2% and 58.8%, respectively, whereas the PDE4 inhibitors cilomilast (30 μM) and roflumilast (0.3 μM) did not. In both cell types, a concentration-dependent inhibition of E-selectin expression by tetomilast (5 to 30 μM) was observed with both 30-min and overnight (16-hr) pretreatments, whereas inhibition of ICAM-1 and VCAM-1 was clearly seen only with overnight pretreatment. In contrast, cilomilast, rolipram (both up to 30 μM), and roflumilast (up to 0.3 μM) had no such effect on expression of any of the adhesion molecules. cDNA microarray data showed that preincubation with tetomilast for 6 hr downregulated interferon regulatory factor (IRF)-1 expression. Using a luciferase-based IRF-1 pathway-specific reporter assay in HLMVEC, the inhibitory effect of tetomilast on IRF-1 pathway was observed over the same concentration range. Conclusions: Tetomilast may mediate its anti-inflammatory effect partially through the inhibition of vascular permeability increase and adhesion molecule expression, independent of PDE4 inhibition. Our data indicate that tetomilast inhibits VCAM-1 and ICAM-1 expression on EC, likely by inhibiting IRF-1 pathway.

Various adhesion molecules impair microvascular leukocyte kinetics in ventilator-induced lung injury

Although the endothelial expression of various adhesion molecules substantially differs between pulmonary microvessels, their importance for neutrophil and lymphocyte sequestration in ventilator-induced lung injury (VILI) has not been systematically analyzed. We investigated the kinetics of polymorphonuclear cells (PMN) and mononuclear cells (MN) in the acinar microcirculation of the isolated rat lung with VILI by real-time confocal laser fluorescence microscopy, with or without inhibition of ICAM-1, VCAM-1, or P-selectin by monoclonal antibodies (MAb). Adhesion molecules in each microvessel were estimated by intravital fluorescence microscopy or immunohistochemical staining. In high tidal volume-ventilated lungs, 1) ICAM-1, VCAM-1, and P-selectin were differently upregulated in venules, arterioles, and capillaries; 2) venular PMN rolling was improved by inhibition of ICAM-1, VCAM-1, or P-selectin, whereas arteriolar PMN rolling was improved by ICAM-1 or VCAM-1 inhibition; 3) capillary PMN entrapment was ameliorated only by anti-ICAM-1 MAb; and 4) MN rolling in venules and arterioles and MN entrapment in capillaries were improved by ICAM-1 and VCAM-1 inhibition. In conclusion, the contribution of endothelial adhesion molecules to abnormal leukocyte behavior in VILI-injured microcirculation is microvessel and leukocyte specific. ICAM-1- and VCAM-1-dependent, but P-selectin-independent, arteriolar PMN rolling, which is expected to reflect the initial stage of tissue injury, should be taken as a phenomenon unique to ventilator-associated lung injury.

Inhibition of ICAM-1/LFA-1 interaction prevents allograft tolerance induced by anti-CD45RB

Abstract Introduction: Long-term allograft tolerance may be established by elimination of peripheral graft-reactive cell, by the induction of regulatory cells, or by induced ignorance through alteration of lymphocyte trafficking. We have investigated the contribution of the intracellular adhesion molecules ICAM-1/LFA-1 to tolerance induced by anti-CD45RB. Methods: Cardiac allografts from C3H mice were transplanted to either wild-type or ICAM-deficient C57BL/6 mice. Recipients were untreated, treated with anti-CD45RB mAb (100ug ip days 0, 1, 3, 5, and 7), or treated with a combination of anti-CD45RB and anti ICAM-1 or anti-LFA1 (50ug ip x5). Immunophenotyping of B cells by flow cytometry was performed after exposure of mice to alloantigen and anti-CD45RB. Results: Exposure of lymphocytes in vivo to anti-CD45RB and alloantigen induces upregulation of ICAM-1 on B cells. Although treatment with anti-CD45RB uniformly establishes permanent acceptance of C3H allografts (MST > 100days, n = 14), coadministration of either anti-ICAM-1 or anti-LFA-1 prevents tolerance induction (MST = 28.25 ± 2.96 and 14 ± 3.11 days, respectively). Neither anti-ICAM-1 or anti-LFA-1 therapy alone induced permanent allograft survival despite modest prolongation of survival. Treatment of genetically ICAM deficient B6 animals with anti-CD45RB also failed to induce tolerance (MST = 23.66 ± 3.57 days). Conclusions: These data suggest the involvement of ICAM-1/LFA-1 interactions during tolerance induction mediated by anti-CD45RB. Whether this effect is mediated by inter- or intracellular signaling through these molecules or by alterations of lymphocyte trafficking patterns is under investigation.

Membrane-bound ICAM-1 is upregulated by trypsin and contributes to leukocyte migration in acute pancreatitis.

In acute pancreatitis, ICAM-1 is upregulated in various organs and contributes to the development of organ injury. To investigate the effects of pancreatic proteases on ICAM-1 expression and their role in the early process of leukocyte migration, human umbilical vein endothelial cells (HUVECs) were incubated with serum subjected to limited trypsin digestion and Wistar rats were injected with trypsin. Significant upregulation of membrane-bound ICAM-1 was seen on HUVECs incubated with trypsinated serum. Likewise, soluble ICAM-1 increased in the supernatant of HUVECs. Changes of membrane-bound ICAM-1 and soluble ICAM-1 were maximal with high concentrations of trypsin. HUVECs incubated with TNF-alpha (positive control) showed similar changes. In the pancreas and lungs of animals infused with trypsin, ICAM-1 and leukocyte sequestration were increased compared with controls. Reflecting the relevance of protease-induced ICAM-1 expression in leukocyte migration, leukocyte-endothelium interaction, as assessed by intravital microscopy, was markedly increased by trypsin. Inhibition of ICAM-1 ameliorated these changes significantly. In conclusion, trypsinated serum induces the upregulation of both membrane-bound ICAM-1 on endothelial cells and soluble ICAM-1. These changes contribute to the early steps of leukocyte migration in acute pancreatitis. The role of soluble ICAM-1 remains to be investigated.

Inhibition of ICAM-1/LFA-1-mediated heterotypic T-cell adhesion to epithelial cells: design of ICAM-1 cyclic peptides

In this work, we have designed cyclic peptides (cIBL, cIBR, cIBC, CH4 and CH7) derived from the parent IB peptide (ICAM-1 1–21) that are inhibitors of ICAM-1/LFA-1-mediated T-cell adhesion to Caco-2 cell monolayers. Cyclic peptide cIBR has the best activity of any of the peptides evaluated. The active ICAM-1 peptides have a common Pro-Arg-Gly sequence that may be important for binding to LFA-1.