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Results for “Integrin alpha4”

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PubMed2001

alpha4 integrin in islet allograft rejection.

BACKGROUND: Adhesion molecules are involved in multiple steps of the continuum of allograft rejection. We studied the effects of blockade of the interactions between alpha4 integrin and its ligands, vascular cell adhesion molecule-1 (VCAM-1) and fibronectin, on allograft survival. METHODS: Streptozotocin-induced diabetic CBA (H-2k) mice received islet transplants from BALB/c (H-2d) donors. Recipient mice were treated with antibodies against alpha4 integrin (PS/2), VCAM-1 (MK 2.7), and a peptide corresponding to the binding site of alpha4 integrin on fibronectin (connecting segment 1 peptide, CS1-peptide). Graft function was measured by daily tail vein blood glucose levels, with rejection defined as the return of hyperglycemia. Graft-bearing kidneys were removed for immunohistochemical analysis. RESULTS: Treatment with anti-alpha4 integrin antibody, anti-VCAM-1 antibody, or with CS1-peptide led to long-term survival of islet allografts. Recipients with long-surviving islet grafts did not show tolerance, in that they rejected a second donor-type islet allograft. Although both anti-alpha4 integrin antibody and CS1-peptide completely abolished cellular infiltration of the islet graft 7 days after transplantation, anti-VCAM-1-treated recipients showed a dense peri-islet infiltrate of activated, alpha4 integrin+, cytotoxic T cells. CONCLUSIONS: These data show that alpha4 integrin is critically important to allograft rejection. Anti-VCAM-1 antibody appears to prevent rejection without qualitatively affecting either T cell activation or migration to the graft. Conversely, anti-alpha4 integrin antibody and CS1-peptide may prevent islet allograft rejection by altering either T cell activation or lymphocyte trafficking. Blocking interactions between alpha4 integrin and its ligands may provide novel forms of immunosuppression.

Animals↗

PubMed2000

Effect of antibody against integrin alpha4 on bleomycin-induced pulmonary fibrosis in mice.

Integrins are a family of transmembrane glycoproteins that can interact with components of the extracellular matrix. The alpha4beta1 and alpha4beta7 integrins are heterodimeric leukocyte cell surface molecules critical to their cell and matrix adhesive interactions. Evidence for a central role for the alpha4 integrins in leukocyte pathophysiology in the lung is well documented. In this study, we tested the hypothesis that neutralizing antibody for integrin alpha4 (PS2) may reduce bleomycin (BL)-induced lung fibrosis in vivo. Male C57BL/6 mice were injected intratracheally with saline (SA) or BL (0.08 U/mouse) followed by intraperitoneal injection of SA, isotype control antibody (1E6), or PS2 (100 microg) three times a week. Twenty-one days after the intratracheal instillation, mice were killed for bronchoalveolar lavage (BAL), biochemical, histopathological, and immunohistological analyses. Treatment with PS2 significantly reduced BL-induced increases in lung lipid peroxidation and hydroxyproline content. Lung histopathology also showed reduced fibrotic lesions in the BL-treated lungs by treatment with PS2. BL-treated mouse lungs also showed induction of cells with the myofibroblast phenotype, as indicated by the increased expression of alpha-smooth muscle actin (alphaSMA), whereas treatment with PS2 minimized the BL-induced alphaSMA expression. Furthermore, treatment with PS2 reduced the BL-induced increase in the BAL total cell number, and attenuated the BL-induced increase in the BAL protein level. It is concluded that integrin alpha4 may play an important role in BL-induced pulmonary fibrosis, and the use of anti-alpha4 antibody offers therapeutic antifibrotic potential in vivo.

Actins↗

PubMed2001

A randomized placebo-controlled trial of a humanized monoclonal antibody to alpha4 integrin in active Crohn's disease.

BACKGROUND & AIMS: alpha4 integrins are important mediators of leukocyte migration across vascular endothelium. This pilot placebo-controlled study aimed to assess the safety and efficacy of natalizumab, a recombinant humanized monoclonal antibody to alpha4 integrin, in patients with mild to moderately active Crohn's disease. METHODS: Thirty patients with active Crohn's disease (Crohn's Disease Activity Index [CDAI] > or =151 and < or =450) received a 3-mg/kg infusion of natalizumab (n = 18) or placebo (n = 12) by double-blind randomization. The study's primary endpoint was change in CDAI at week 2. RESULTS: At week 2, the CDAI decreased significantly from baseline after infusion of natalizumab (mean 45 points) but not placebo (mean 11 points). Seven (39%) natalizumab-treated patients achieved remission at week 2, compared with 1 (8%) treated with placebo. In contrast, 4 (33%) of the placebo-treated patients required rescue medication by week 2, compared with 2 (11%) natalizumab-treated patients. Significant increases in circulating B and T lymphocytes were detected only after natalizumab administration. The frequency of commonly reported adverse events did not differ significantly between groups. CONCLUSIONS: A single 3-mg/kg natalizumab infusion was well tolerated by Crohn's disease patients, although the dose used may have been suboptimal. Elevated circulating lymphocyte levels after natalizumab suggest interrupted lymphocyte trafficking. Natalizumab therapy in active Crohn's disease merits further investigation.

Adult↗

PubMed1999

Alpha4 integrins regulate the proliferation/differentiation balance of multilineage hematopoietic progenitors in vivo.

We investigated roles of alpha4 integrins during hematopoiesis using mutant and chimeric mice. Yolk sac erythropoiesis and migration of hematopoietic progenitors to fetal liver, spleen, and bone marrow can occur without alpha4 integrins. Although terminal differentiation of these progenitors is possible without alpha4 integrins, these receptors are essential to maintain normal hematopoiesis in fetal liver, spleen, and bone marrow microenvironments. Moreover, alpha4-deficient erythroid progenitors and pre-B cells neither transmigrate beneath the stroma nor expand-properly in vitro. In contrast, alpha4-null cells migrate and differentiate efficiently into T lymphocytes within the thymus. In summary, alpha4 integrins are essential for normal development of all hematopoietic lineages in fetal liver, bone marrow, and spleen, likely by regulating the proliferation/differentiation balance of hematopoietic progenitors.

Animals↗

PubMed1998

The development of experimental autoimmune encephalomyelitis in the mouse requires alpha4-integrin but not alpha4beta7-integrin.

Because monoclonal antibodies (mAbs) directed against alpha4-integrin and VCAM-1 inhibit the development of experimental autoimmune encephalomyelitis (EAE) in vivo, it has been concluded that the successful therapeutic effect is due to interference with alpha4beta1/VCAM-1-mediated interaction of autoaggressive T cells with the blood-brain barrier. A possible role for alpha4beta7-integrin, or interference with other T cell mediated events during the pathogenesis of EAE, has not been considered. We have compared the effects of mAb therapy on the development of EAE in the SJL/N mouse, using a large panel of mAbs directed against alpha4, beta7, the alpha4beta7-heterodimer, and against VCAM-1. Although encephalitogenic T cells express both alpha4-integrins, mAbs directed against the alpha4beta7-heterodimer or against the beta7-subunit did not interfere with the development of EAE. In contrast, mAbs directed against alpha4 and VCAM-1 inhibited or diminished clinical or histopathological signs of EAE. Our data demonstrate for the first time that alpha4beta7 is not essential for the development of EAE. Furthermore, our in vitro studies suggest that the therapeutic effect of anti-alpha4-treatment of EAE might also be caused by inhibition of antigen-specific T cell proliferation.

Animals↗

PubMed2006

New approaches to blockade of alpha4-integrins, proven therapeutic targets in chronic inflammation.

The recruitment of leukocytes into tissue is a pivotal step in inflammation. alpha4-Integrins are adhesion receptors on circulating leukocytes that mediate attachment to the endothelium and facilitate their migration into the inflamed tissue. This multistep process is mediated by the interaction of alpha4-integrins with their counter receptors VCAM-1 and MadCAM-1 that are expressed on endothelial cells. alpha4-Integrins act as both adhesive and signaling receptors. Paxillin, a signaling adaptor molecule, binds directly to the alpha4 cytoplasmic tail and its binding is important for cell migration. Blocking the adhesive functions of alpha4-integrins has been shown to be an effective therapeutic approach in the treatment of autoimmune diseases, but also carries the risk of defects in development, hematopoiesis and immune surveillance. Interfering with alpha4 signaling by inhibiting the alpha4-paxillin interaction decreases alpha4-mediated cell migration and adhesion to VCAM-1 and MadCAM under shear flow. These in vitro effects are accompanied by a selective impairment of leukocyte migration into inflammatory sites when the alpha4-paxillin interaction is blocked in vivo. Thus, blockade of alpha4-integrin signaling may offer a novel strategy for interfering with the functions of these receptors in pathological events while sparing important physiological functions.

Animals↗

PubMed2000

Expression of vascular cell adhesion molecule-1, alpha4-integrin and L-selectin during inner ear immunity reaction.

The expression of vascular cell adhesion molecule-1 (VCAM-1), alpha4-integrin and L-selectin was dynamically observed using an immunohistochemical approach during labyrinthitis induced by inoculation of keyhole limpet hemocyanin into the scala tympani of animals that had been systemically sensitized to it. At the same time, we used ELISA to monitor interleukin-1(IL-1) in the peripheral blood of these animals. The expression of alpha4-integrin and L-selectin on the surface of leukocytes in peripheral blood was examined by flow cytometry. VCAM-1 was found on the endothelial surface of the spiral modiolar vein (SMV) and its collecting venules (CV) at 24 h post-challenge; the VCAM-1 level reached a maximum on day 2, which was maintained until 1 week post-challenge, and then declined gradually. Alpha4-integrin was found on the surface of leukocytes, mainly monocytes and lymphocytes, that had infiltrated the SMV, CV, cochlear nerve and perilymph by 24 h post-challenge; the alpha4-integrin level reached a maximum on day 2 and then decreased rapidly. At 1 week post-challenge, no significant expression of alpha4-integrin was seen. Expression of alpha4-integrin and L-selectin was also observed on leukocytes in peripheral blood. No L-selectin was observed on the surface of leukocytes during inner ear inflammation. The expression of L-selectin on the surface of leukocytes in the peripheral blood appeared to be downregulated during inflammation. The concentrations of IL-1 in the peripheral blood increased commensurately during inner ear inflammation. These results further elucidate the role of adhesion molecules during inner ear immune responses. The increased expression of VCAM-1 on SMV and CV was correlated with the concentration of IL-1 in peripheral blood during inner ear inflammation.

Animals↗

PubMed2003

Inhibition of alpha4-integrin stimulates epicardial-mesenchymal transformation and alters migration and cell fate of epicardially derived mesenchyme.

Epithelial-mesenchymal transformation of the embryonic epicardium produces the subepicardial mesenchyme that is essential for normal coronary vascular development. Gene targeting experiments in mice have demonstrated an essential role for alpha4-integrin in normal epicardial development, but the precise cellular consequences of alpha4-integrin loss remain uncertain. To better understand the function of alpha4-integrin in epicardial development, we constructed a replication-incompetent adenovirus (AdlacZalpha4AS) that expresses antisense chicken alpha4-integrin as the 3' untranslated region of a lacZ reporter gene. This construct effectively labeled cells while greatly reducing levels of alpha4-integrin mRNA and protein. In quail chick chimeras, transplanted epicardial cells infected with AdlacZalpha4AS adhered to the heart and were incorporated into the epicardium, but 4 days after grafting, were largely absent from the epicardial epithelium, recapitulating the defect in alpha4-null mice. This did not result from epicardial cell apoptosis or anomalous migration of epicardial cells to extracardiac sites. Rather, AdlacZalpha4AS-infected epicardial cells were particularly invasive, being three to four times more likely to migrate to the interstitium of the myocardium than AdlacZ-infected epicardial cells. Accelerated epicardial-mesenchymal transformation and migration of alpha4-negative epicardium was observed in an organ culture system that does not require prior culture of epicardial cells. Remarkably, AdlacZalpha4AS infection also prevented targeting of epicardially derived mesenchyme to the media of developing coronary vasculature in the myocardial interstitium. This study provides evidence that epicardial alpha4-integrin normally restrains epicardial-mesenchymal transformation, invasion, and migration and is essential for correct targeting of epicardially derived mesenchyme to the developing coronary vasculature.

Adenoviridae↗

PubMed2000

Distinct roles for matrix metalloproteinase-2 and alpha4 integrin in autoimmune T cell extravasation and residency in brain parenchyma during experimental autoimmune encephalomyelitis.

Expression of alpha4 integrin by auto-reactive T cells is critical for their ability to induce EAE, an autoimmune disease of the central nervous system in mice, used as a model to study human multiple sclerosis. Having previously identified one role for alpha4 integrin in adhesion-mediated induction of matrix metalloproteinase-2 (MMP-2), an enzyme that degrades the subendothelial basement membrane matrix, we investigated independent roles for MMP-2 and alpha4 integrin during EAE. The data suggest that expression of alpha4 integrin by auto-reactive T cells is important not only in mediating MMP-2 induction to facilitate entry into the CNS, but also plays a role in maintaining residency within the CNS.

Animals↗

PubMed2005

Suppression of acute experimental allergic encephalomyelitis with a small molecule inhibitor of alpha4 integrin.

PURPOSE: To determine the efficacy of a small molecule inhibitor of alpha4 integrin (CT301) at reversing the clinical, pathological and MR-detectable deficits associated with the acute phase of experimental allergic encephalomyelitis (EAE). MATERIALS AND METHODS: EAE was induced in 36 female Hartley guinea pigs, and the treatment period was from day 11 to day 17 post-immunization. Animals received either saline (n = 12), anti-alpha4 integrin antibody (AN100226m; n = 12) or CT301 (n = 12). T2-weighted fast spin echo and T1-weighted pre- and post-contrast scans were performed at the beginning (day 11) and end (day 18) of the treatment period, and scored for cerebral inflammation and gadolinium enhancement. T1-weighted images were further analyzed to quantify this enhancement as a measure of blood-brain barrier integrity. Dissected CNS was evaluated for inflammation and demyelination. RESULTS: CT301 successfully reversed two clinical indicators of disease over the course of the treatment period. These animals showed decreased T2-weighted abnormalities, as well as a reduction in gadolinium leakage on T1-weighted images. Meningeal and perivascular inflammation was decreased by anti-alpha4 integrin treatments. CONCLUSION: CT301 effectively reverses the clinical, pathological and MR-detectable deficits of acute EAE, and may therefore be a promising therapeutic agent in multiple sclerosis (MS).

Acute Disease↗

PubMed2003

PSGL-1 participates in E-selectin-mediated progenitor homing to bone marrow: evidence for cooperation between E-selectin ligands and alpha4 integrin.

The nature and exact function of selectin ligands involved in hematopoietic progenitor cell (HPC) homing to the bone marrow (BM) are unclear. Using murine progenitor homing assays in lethally irradiated recipients, we found that the P-selectin glycoprotein ligand-1 (PSGL-1) plays a partial role in HPC homing to the BM (a reduction of about 35% when the P-selectin binding region is blocked). Blockade of both PSGL-1 and alpha4 integrin did not further enhance the effect of anti-alpha4 integrin (a reduction of about 55%). We suspected that E-selectin ligands might contribute to the remaining homing activity. To test this hypothesis, HPC homing assays were carried out in E-selectin-deficient recipients and revealed a profound alteration in HPC homing when E-selectin and alpha4 integrin were inactivated (> 90% reduction). Competitive assays to test homing of long-term repopulating stem cells revealed a drastic reduction (> 99%) of the homed stem cell activity when both alpha4 integrin and E-selectin functions were absent. Further homing studies with PSGL-1-deficient HPCs pretreated with anti-alpha4 integrin antibody revealed that PSGL-1 contributes to approximately 60% of E-selectin ligand-mediated homing activity. Our results thus underscore a major difference between mature myeloid cells and immature stem/progenitor cells in that E-selectin ligands cooperate with alpha4 integrin rather than P-selectin ligands.

Animals↗

PubMed2001

Alpha4 integrin is expressed during peripheral nerve regeneration and enhances neurite outgrowth.

We have shown previously that repair in the peripheral nervous system is associated with a reversion to an embryonic pattern of alternative splicing of the extracellular matrix molecule fibronectin. One of the consequent changes is a relative increase in the number of fibronectins expressing the binding site for alpha4 integrins. Here we show that alpha4 integrins are expressed on dorsal root ganglion neuron cell bodies and growth cones in the sciatic nerve during regeneration and that the interaction of alpha4 integrin with alternatively spliced isoforms of recombinant fibronectins containing the alpha4 binding site enhances neurite outgrowth in dorsal root ganglion neurons. The pheochromocytoma (PC12) neuronal cell line, which normally extends neurites poorly on fibronectin, does so efficiently when alpha4 is expressed in the cells. Experiments using chimeric integrins expressed in PC12 cells show that the alpha4 cytoplasmic domain is necessary and sufficient for this enhanced neurite outgrowth. In both dorsal root ganglion neurons and PC12 cells the alpha4 cytoplasmic domain is tightly linked to the intracellular adapter protein paxillin. These experiments suggest an important role for alpha4 integrin and paxillin in peripheral nerve regeneration and show how alternative splicing of fibronectin may provide a mechanism to enhance repair after injury.

Alternative Splicing↗

PubMed2001

Functional alpha4-integrin: a newly identified pathway of neutrophil recruitment in critically ill septic patients.

Using a novel flow chamber assay system and whole blood, we show that leukocytes from septic individuals have a four-fold elevation of adhesion, but not rolling, on a P-selectin/beta2-integrin substrate. Most leukocytes from septic patients (but not healthy controls) that bound vascular cell adhesion molecule 1 (VCAM-1) were neutrophils. All adhesion was inhibited with an antibody specific for the VCAM-1 ligand alpha4-integrin. The alpha4-integrin was present on neutrophils from septic patients but not on neutrophils from patients with localized bacterial infections. The plasma milieu of septic patients was sufficient to induce neutrophils from healthy subjects to bind VCAM-1 under flow conditions. This is the first description of alpha4-integrin/VCAM-1 pathway of neutrophil recruitment in human disease. This pathway may provide a new therapeutic target to reduce inappropriate neutrophil adhesion without altering the normal yet critical beta2-integrin-mediated adhesive function of neutrophils.

Adult↗

PubMed2005

The expression of alpha4 integrins by human polymorphonuclear neutrophils in response to sonicated extracts of Enterococcus faecalis.

This study was undertaken to investigate immunopathologic mechanism of Enterococcus faecalis in relation to persistent apical periodontitis. We monitored the expression levels of alpha4 integrin in human polymorphonuclear neutophils (PMNs) after stimulated with sonicated extracts of E. faecalis (SEF) and compared with lipopolycaccarides (LPS) of Escherichia coli for various incubation time. Venous blood was collected from healthy volunteers and then PMNs were isolated and cultured with various concentrations of SEF for different periods of time. The levels of alpha4 integrin were measured by flow cytometry analysis. E. coli LPS group was used as a positive control and untreated PMNs as a negative control. Results showed that the expressions levels of alpha4 integrin were increased in human PMNs stimulated with E. coli LPS in comparison with unstimulated control cells (p < 0.05). In case of SEF stimulated group, the expression levels were decreased in time-dependent manner in comparison to E. coli LPS group (p < 0.05). Notably, after 12 h for incubation with SEF, the expression of alpha4 integrin was decreased in dose-dependent manner (p < 0.05). These findings suggest that E. faecalis seem to suppress PMNs recruiting activity by down-regulating alpha4 integrin expression, providing the possible mechanism that E. faecalis may play a crucial role in persistent apical periodontitis.

Analysis of Variance↗

PubMed2001

Effect of alpha4-integrin blockade on CD4+ cell-driven late airway responses in the rat.

The blockade of alpha4 integrins with a monoclonal antibody (TA-2) decreases late airway responses (LR) in ovalbumin (OVA)-sensitized and challenged rats. In this study, we used a model of CD4+ cell-driven LR to test the hypothesis that alpha4-integrin blockade involves interference with T-cell activation in the inhibition of LR. Purified CD4+ cells from OVA-sensitized rats were transferred to unsensitized recipients, which received either TA-2 or a control antibody (cAb), and were OVA-challenged. A sham-challenged group was also studied. LR, calculated from pulmonary resistance after challenge, were reduced in the TA-2 group compared with the cAb group (p = 0.015). Total cell counts, macrophages, neutrophils, and lymphocytes in bronchoalveolar lavage (BAL), and CD3+ cells in airway sections, were unaffected. The cAb group had higher numbers of cells expressing interleukin-5 (IL-5) mRNA (55.2 +/- 3.39 cells/1,000, mean +/- SEM) and major basic protein (MBP) (6.2 +/- 0.4/100 cells) in bronchoalveolar lavage (BAL), than the TA-2 group (25.37 +/- 2.41 IL-5+ and 2.7 +/- 0.2 MBP+) and the sham group (12.37 +/- 0.96 IL-5+, 1.7 +/- 0.1 MBP+). Interferon gamma (IFN-gamma) mRNA+ cells were downregulated in both OVA-challenged groups, compared with the sham group. Our results suggest that the attenuation of LR and eosinophilia by alpha4-integrin blockade may involve interference with CD4+ cell activation and IL-5 expression.

Animals↗

PubMed1997

Airway recruitment of leukocytes in mice is dependent on alpha4-integrins and vascular cell adhesion molecule-1.

The involvement of the alpha4-integrin very late activation antigen 4 and vascular cell adhesion molecule-1 (VCAM-1) in leukocyte trafficking into the airways of ovalbumin (OA)-sensitized and OA-challenged mice was investigated using in vivo administration of anti-alpha4 monoclonal antibodies (mAb) PS/2, R1-2, and M/K-2.7 (MK2), specific for VCAM-1. VCAM-1 was upregulated on endothelial cells in lung tissue after OA inhalation. PS/2, R1-2, or MK2 significantly inhibited the recruitment of eosinophils and lymphocytes into the bronchoalveolar lavage (BAL) fluid and decreased inflammation in the lung tissues. Escalating in vivo doses of PS/2 or MK2 increased circulating levels of rat immunoglobulin G in the plasma. The binding of phycoerytherin-labeled anti-alpha4 mAb to blood T cells from PS/2-treated mice was reduced, implying that alpha4 sites were already occupied. T cells and eosinophils in BAL fluid from mice treated with PS/2 or MK2 were phenotypically different from controls. Selective decreases of alpha4+ T cells in the BAL fluid after PS/2 or MK2 treatment were coupled with changes in CD8+, CD11a, and CD62L expression. The alpha4-integrin and VCAM-1 may have important roles in the antigen-induced recruitment of T cells and eosinophils during OA-induced airway inflammation. The data suggest that these adhesion molecules may be suitable targets for therapeutic intervention in certain conditions of pulmonary inflammation.

Animals↗

PubMed2003

Deletion of alpha4 integrins from adult hematopoietic cells reveals roles in homeostasis, regeneration, and homing.

We have explored the functional implications of inducible alpha4 integrin deletion during adult hematopoiesis by generating a conditional-knockout mouse model, and we show that alpha4 integrin-deficient hematopoietic progenitor cells accumulate in the peripheral blood soon after interferon-induced gene deletion. Although their numbers gradually stabilize at a lower level, progenitor cell influx into the circulation continues at above-normal levels for more than 50 weeks. Concomitantly, a progressive accumulation of progenitors occurs within the spleen. In addition, the regeneration of erythroid and myeloid progenitor cells is delayed during stress hematopoiesis induced by phenylhydrazine or by 5-fluorouracil, suggesting impairment in early progenitor expansion in the absence of alpha4 integrin. Moreover, in transplantation studies, homing of alpha4(-/-) cells to the bone marrow, but not to the spleen, is selectively impaired, and short-term engraftment is critically delayed in the early weeks after transplantation. Thus, conditional deletion of alpha4 integrin in adult mice is accompanied by a novel hematopoietic phenotype during both homeostasis and recovery from stress, a phenotype that is distinct from the ones previously described in alpha4 integrin-null chimeras and beta1 integrin-conditional knockouts.

Anemia, Hemolytic↗

PubMed1997

The association between alpha4-integrin, P-selectin, and E-selectin in an allergic model of inflammation.

In this study, we examined the relationship between the endothelial selectins (P-selectin and E-selectin) and whether they are critical for alpha4-integrin-dependent leukocyte recruitment in inflamed (late phase response), cremasteric postcapillary venules. Animals were systemically sensitized and 2 wk later challenged intrascrotally with chicken ovalbumin. Leukocyte rolling flux, adhesion, and emigration were assessed at baseline and 4 and 8 h postantigen challenge. There was a significant increase in leukocyte rolling flux, adhesion, and emigration in sensitized and challenged mice at both 4 and 8 h. At 8 h, the increase in leukocyte rolling flux was approximately 50% inhibitable by an anti-alpha4-integrin antibody, 98% inhibitable by fucoidin (a selectin-binding carbohydrate), and 100% inhibitable by an anti-P-selectin antibody. P-selectin-deficient animals displayed no leukocyte rolling or adhesion at 8 h after challenge. However, at 8 h there were many emigrated leukocytes in the perivascular space suggesting P-selectin-independent rolling at an earlier time point. Indeed, at 4 h postantigen challenge in P-selectin-deficient mice, there was increased leukocyte rolling, adhesion, and emigration. The rolling in the P-selectin-deficient mice at 4 h was largely alpha4-integrin dependent. However, there was an essential E-selectin-dependent component inasmuch as an anti-E-selectin antibody completely reversed the rolling, and in E-selectin and P-selectin double deficient mice rolling, adhesion and emigration were completely absent. These results illustrate that P-selectin underlies all of the antigen-induced rolling with a brief transient contribution from E-selectin in the P-selectin-deficient animals. Finally, the antigen-induced alpha4-integrin-mediated leukocyte recruitment is entirely dependent upon endothelial selectins.

Animals↗