Adhesion molecule cascades direct lymphocyte recirculation and leukocyte migration during inflammation

The Cancer Cell Dissemination Machinery as an Immunosuppressive Niche: A New Obstacle Towards the Era of Cancer Immunotherapy

Although cancer immunotherapy has resulted in unpreceded survival benefits to subsets of oncology patients, accumulating evidence from preclinical animal models suggests that the immunosuppressive tumor microenvironment remains a detrimental factor limiting benefit for many patient subgroups. Recent efforts on lymphocyte-mediated immunotherapies are primarily focused on eliminating cancer foci at primary and metastatic sites, but few studies have investigated the impact of these therapies on the highly complex process of cancer cell dissemination. The metastatic cascade involves the directional streaming of invasive/migratory tumor cells toward specialized blood vessel intravasation gateways, called TMEM doorways, to the peripheral circulation. Importantly, this process occurs under the auspices of a specialized tumor microenvironment, herewith referred to as “Dissemination Trajectory”, which is supported by an ample array of tumor-associated macrophages (TAMs), skewed towards an M2-like polarization spectrum, and which is also vital for providing microenvironmental cues for cancer cell invasion, migration and stemness. Based on pre-existing evidence from preclinical animal models, this article outlines the hypothesis that dissemination trajectories do not only support the metastatic cascade, but also embody immunosuppressive niches, capable of providing transient and localized immunosubversion cues to the migratory/invasive cancer cell subpopulation while in the act of departing from a primary tumor. So long as these dissemination trajectories function as “immune deserts”, the migratory tumor cell subpopulation remains efficient in evading immunological destruction and seeding metastatic sites, despite administration of cancer immunotherapy and/or other cytotoxic treatments. A deeper understanding of the molecular and cellular composition, as well as the signaling circuitries governing the function of these dissemination trajectories will further our overall understanding on TAM-mediated immunosuppression and will be paramount for the development of new therapeutic strategies for the advancement of optimal cancer chemotherapies, immunotherapies, and targeted therapies.

Relationship between vascular cell adhesion molecule-1 (VCAM-1), soluble receptor for advanced glycation end products (sRAGE) and functional hemodynamic parameters of arteriovenous fistula

BACKGROUND

The preferred vascular access for hemodialysis is represented by arteriovenous fistula (AVF) due to fewer complications and more prolonged survival. Considerable efforts have been made to identify biomarkers associated with AVF dysfunction, but results are conflicting. Vascular cell adhesion molecule (VCAM-1) and advanced glycation end products are involved in atherogenesis, vascular calcification, peripheral artery disease, and neointimal hyperplasia in renal and non-renal patients. The objective of this study was to evaluate whether there is an association between VCAM-1, soluble receptor for advanced glycation end products (sRAGE), NcarboxymethylLysine (CML), and arteriovenous fistula dysfunction (AVF).

METHODS

VCAM-1, sRAGE, and CML were performed using the ELISA technique in 88 HD patients. Ultrasound assessment of AVF reports brachial artery blood flow (Qa), brachial resistivity index (RI), presence of calcification, and the diameter. AVF dysfunction was defined as a brachial artery Qa ⩽ 500 ml/min or RI ⩾ 0.5.

RESULTS

The median level of VCAM-1 [2676.5(2206.8-4203.9) versus 2613.2(1885.7-3161.8), p 0.026] was significantly higher in patients with AVF dysfunction compared to the rest of the patients. sRAGE and CML were higher in this group but without statistical significance. In patients with AVF dysfunction, significant positive correlations were found between VCAM-1and sRAGE (r = 0.417, p = 0.001), RI (r = 0.313, p = 0.046), dialysis vintage (r = 0.540, p < 0.001), AVF vintage (r = 0.336, p = 0.032), intima-media thickness (r = 0.423, p = 0.006) and C-reactive protein (r = 0.315, p = 0.045). VCAM-1 correlated inversely with cholesterol (r = -0.312, p = 0.047), triglycerides (r = -0.358, p = 0.021), body mass index (r = -0.388, p = 0.012). In multivariate regression analysis, VCAM-1 (p = 0.013) and sRAGE (p = 0.01) remained significant predictors of RI and Qa. Logistic regression disclosed calcification, VCAM-1, as risks factors for AVF dysfunction.

CONCLUSION

The results we obtained showed that patients with AVF dysfunction had a significantly higher level of VCAM-l. A positive correlation between VCAM-1 and sRAGE was identified in this group.

MICROVASCULAR FLOW ABNORMALITIES ASSOCIATED WITH RETINAL VASCULITIS: A Potential of Mechanism of Retinal Injury

PURPOSE

To investigate the structural optical coherence tomography and related microvascular flow characteristics in eyes with retinal vasculitis.

METHODS

Regions involved with perivascular infiltration in eyes with retinal vasculitis, but no evidence of large vessel occlusion were evaluated with optical coherence tomography (OCT), OCT angiography, and fluorescein angiography.

RESULTS

Ten eyes of 5 patients with a variety of etiologies of retinal vasculitis were evaluated. These patients did not have either cotton wool spots or deeper placoid areas of retinal ischemia. Around large vessels there was perivascular infiltration with leakage and staining seen during fluorescein angiography. Structural OCT showed slight thickening with loss of visualization of normal retinal laminations. OCT angiography showed a lack of flow signal in capillary sized vessels in the same areas. Treatment resulted in a rapid thinning of the affected areas, with the inner and middle layers of the retina becoming thinner than surrounding uninvolved areas. OCT angiography did not show a return of capillary perfusion in these regions. The thickness change in the structural OCT as shown by a heat map had a pattern mimicking the original perivascular infiltration around large retinal vessels.

CONCLUSION

Capillary level perfusion abnormalities can develop in regions adjacent to large vessel inflammatory infiltrate that result in retinal thinning without the development of usual stigmata of acute microvascular flow obstruction such as cotton wool spots. This suggests that retinal damage may occur in retinal vasculitis that would not be recognized without using OCT-based imaging modalities.

Optical coherence tomography angiography

Optical coherence tomography (OCT) was one of the biggest advances in ophthalmic imaging. Building on that platform, OCT angiography (OCTA) provides depth resolved images of blood flow in the retina and choroid with levels of detail far exceeding that obtained with older forms of imaging. This new modality is challenging because of the need for new equipment and processing techniques, current limitations of imaging capability, and rapid advancements in both imaging and in our understanding of the imaging and applicable pathophysiology of the retina and choroid. These factors lead to a steep learning curve, even for those with a working understanding dye-based ocular angiography. All for a method of imaging that is a little more than 10 years old. This review begins with a historical account of the development of OCTA, and the methods used in OCTA, including signal processing, image generation, and display techniques. This forms the basis to understand what OCTA images show as well as how image artifacts arise. The anatomy and imaging of specific vascular layers of the eye are reviewed. The integration of OCTA in multimodal imaging in the evaluation of retinal vascular occlusive diseases, diabetic retinopathy, uveitis, inherited diseases, age-related macular degeneration, and disorders of the optic nerve is presented. OCTA is an exciting, disruptive technology. Its use is rapidly expanding in clinical practice as well as for research into the pathophysiology of diseases of the posterior pole.

Resolvin D1 attenuates imiquimod-induced mice psoriasiform dermatitis through MAPKs and NF-κB pathways

BACKGROUND

Resolvin D1 (RvD1), a pro-resolution lipid mediator derived from docosahexaenoic acid (DHA), has been described to promote several kinds of inflammatory resolution. However, the effects and anti-inflammatory mechanisms of RvD1 on psoriasis have not been previously reported.

OBJECTIVE

The present study aimed to determine the protective effects and the underlying mechanisms of RvD1 on imiquimod (IMQ)-induced psoriasiform dermatitis.

METHODS

Mice were topically treated with IMQ to develop psoriasiform dermatitis on their shaved back, pretreated intraperitoneally (i.p.) with or without RvD1 or tert-butoxycarbonyl Met-Leu-Phe peptide (Boc), a lipoxin A4 (ALX) receptor antagonist. The severity was monitored and graded using a modified human scoring system, the Psoriasis Area and Severity Index (PASI), histopathology, and the signature cytokines of psoriasis (IL-23, IL-17, IL-22 and TNF-α). The mRNA and protein levels of inflammatory cytokines were quantified by quantitative real-time PCR (QRT-PCR) and ELISA. The expressions of signaling proteins MAPKs and NF-κB p65 were analyzed using western blotting. Electrophoretic mobility shift assay (EMSA) was used to check NF-κB p65 DNA binding activity.

RESULTS

Our study showed that RvD1 alleviated IMQ-induced psoriasiform dermatitis and improved skin pathological changes. RvD1 markedly inhibited IMQ-induced activation of ERK1/2, p38, JNK (c-Jun N-terminal protein kinase, a subfamily of MAPKs), and NF-κB. Furthermore, pretreatment with Boc, would not exacerbate skin inflammation of IMQ-induced mice, but significantly reversed the beneficial effects of RvD1 on IMQ-induced psoriasiform inflammation.

CONCLUSION

RvD1 can obviously improve skin inflammation in IMQ-induced mice psoriasiform dermatitis. The protective mechanisms might be related to its selective reaction with lipoxin A4 receptor/Formyl-peptide receptor 2 (ALX/FPR2), by downregulating relevant cytokines of the IL-23/IL-17 axis expression, the inhibition of MAPKs and NF-κB signaling transduction pathways. Thus, these results show that RvD1 could be a possible candidate for psoriasis therapy.

The α1,3-fucosyltransferase FUT7 regulates IL-1β-induced monocyte-endothelial adhesion via fucosylation of endomucin

Monocyte-endothelial adhesion is a hallmark feature of atherosclerosis at early stage and emerging evidence suggests that the glycosylation of vascular adhesive molecules and its ligands is involved in this process. Nevertheless, the mechanism underlying this process remains incompletely elucidated. In this study, we reported that treatment with inflammatory factors interleukin-1β (IL-1β) pronouncedly upregulated α1,3-fucosyltransferase VII gene (FUT7) mRNA and protein expression level in EA.hy926 endothelial cells. Moreover, FUT7 overexpression significantly promoted monocyte-endothelial adhesion, while FUT7 knockdown obviously inhibited IL-1β-induced monocyte-endothelial adhesion. Further analysis demonstrated that fucosylation of selectin ligand endomucin was directly involved in IL-1β-induced monocyte-endothelial adhesion. Finally, we demonstrated that p38 and extracellular signal-regulated kinase (ERK) MAPK signaling pathway was activated by IL-1β, while inhibition of p38/ERK signaling pathway decreased FUT7 expression level and IL-1β-induced monocyte-endothelial adhesion. In summary, these results provide a novel insight that FUT7-mediated fucosylation contribute to the initiation and progression of atherosclerosis.

Ethanol Extract of Brassica rapa ssp. pekinensis Suppresses Tumor Necrosis Factor-α-Induced Inflammatory Response in Human Umbilical Vein Endothelial Cells

Brassica rapa L. ssp. pekinensis, commonly known as Chinese cabbage, is a cruciferous vegetable traditionally consumed in east Asia. Although its habitual consumption could account for the low incidence of chronic vascular inflammation, the therapeutic and protective potential of phytochemicals derived from Chinese cabbage has been poorly studied. In this study, we identified the phenolic compounds, kaempferol and quercetin, from the ethanol extract of Chinese cabbage (EtCC). We show for the first time that EtCC contains effective phytochemicals that suppress tumor necrosis factor (TNF)-α-induced inflammatory response in human umbilical vein endothelial cells. The EtCC inhibited TNF-α-induced monocyte adhesion to endothelial cells in a dose-dependent manner. The antiadhesive activity of EtCC directly correlated with downregulation of expression and transcription of vascular cell adhesion molecule-1 (VCAM-1). It was caused by an Nrf-2-dependent mechanism, leading to activation of antioxidant responsive element-driven promoter. Taken together, these results suggest that EtCC inhibits the expression of TNF-α-induced adhesion molecules through the indirect transcriptional modulation of VCAM-1 in endothelial cells. In conclusion, regular consumption of vegetables containing dietary phytochemicals might be a potential therapeutic strategy to protect against various stresses, to prevent several pathological conditions, and to treat chronic vascular inflammation, such as atherosclerosis.

Soluble Vascular Cell Adhesion Molecules May be Protective of Future Cardiovascular Disease Risk: Findings from the PREVEND Prospective Cohort Study

Aim: Soluble cell adhesion molecules, such as vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1, E-selectin, and P-selectin, have been suggested to be associated with cardiovascular disease (CVD) risk; however, the nature and magnitude of the association between VCAM-1 and CVD risk is uncertain. We aimed to assess the association of VCAM-1 with CVD risk and determine its potential utility for CVD risk prediction.

Methods: VCAM-1 concentrations were measured at baseline in the PREVEND prospective study of 2,638 participants. Hazard ratios (95% confidence intervals [CI]) and measures of risk discrimination for CVD (e.g., C-index) and reclassification (i.e., net reclassification improvement) of participants were assessed.

Results: During a median follow-up of 9.9 years, 614 CVD events occurred. Plasma VCAM-1 was weakly associated with several cardiovascular risk markers. In analyses adjusted for established cardiovascular risk factors, the hazard ratio (95% CI) for CVD per 1 standard deviation increase in loge VCAM-1 was 0.91 (0.84–0.99; P = 0.020), which remained consistent after additional adjustment for body mass index, alcohol consumption, triglycerides, renal function, and C-reactive protein; hazard ratio (95% CI) 0.89 (0.82–0.97; P = 0.006). Comparing the top versus bottom quintiles of VCAM-1 levels, the corresponding adjusted hazard ratios were 0.74 (0.57–0.96; P = 0.023) and 0.70 (0.54–0.91; P = 0.007) respectively. Adding VCAM-1 to a CVD risk prediction model containing conventional risk factors did not improve the C-index or net reclassification.

Conclusions: Plasma VCAM-1 is inversely and independently associated with CVD. However, VCAM-1 provides no significant improvement in CVD risk assessment beyond conventional CVD risk factors.

Endothelial adhesion molecules and multiple organ failure in patients with severe sepsis

OBJECTIVE

To determine if serum levels of endothelial adhesion molecules were associated with the development of multiple organ failure (MOF) and in-hospital mortality in adult patients with severe sepsis.

DESIGN

This study was a secondary data analysis of a prospective cohort study.

SETTING

Patients were admitted to two tertiary intensive care units in San Antonio, TX, between 2007 and 2012.

PATIENTS

Patients with severe sepsis at the time of intensive care unit (ICU) admission were enrolled. Inclusion criteria were consistent with previously published criteria for severe sepsis or septic shock in adults. Exclusion criteria included immunosuppressive medications or conditions.

INTERVENTIONS

None.

MEASUREMENTS

Baseline serum levels of the following endothelial cell adhesion molecules were measured within the first 72h of ICU admission: Intracellular Adhesion Molecule 1 (ICAM-1), Vascular Cell Adhesion Molecule-1 (VCAM-1), and Vascular Endothelial Growth Factor (VEGF). The primary and secondary outcomes were development of MOF (⩾2 organ dysfunction) and in-hospital mortality, respectively.

MAIN RESULTS

Forty-eight patients were enrolled in this study, of which 29 (60%) developed MOF. Patients that developed MOF had higher levels of VCAM-1 (p=0.01) and ICAM-1 (p=0.01), but not VEGF (p=0.70) compared with patients without MOF (single organ failure only). The area under the curve (AUC) to predict MOF according to VCAM-1, ICAM-1 and VEGF was 0.71, 0.73, and 0.54, respectively. Only increased VCAM-1 levels were associated with in-hospital mortality (p=0.03). These associations were maintained even after adjusting for APACHE and SOFA scores using logistic regression.

CONCLUSIONS

High levels of serum ICAM-1 was associated with the development of MOF. High levels of VCAM-1 was associated with both MOF and in-hospital mortality.

Glia Maturation Factor-γ Regulates Monocyte Migration through Modulation of β1-Integrin

Monocyte migration requires the dynamic redistribution of integrins through a regulated endo-exocytosis cycle, but the complex molecular mechanisms underlying this process have not been fully elucidated. Glia maturation factor-γ (GMFG), a novel regulator of the Arp2/3 complex, has been shown to regulate directional migration of neutrophils and T-lymphocytes. In this study, we explored the important role of GMFG in monocyte chemotaxis, adhesion, and β1-integrin turnover. We found that knockdown of GMFG in monocytes resulted in impaired chemotactic migration toward formyl-Met-Leu-Phe (fMLP) and stromal cell-derived factor 1α (SDF-1α) as well as decreased α5β1-integrin-mediated chemoattractant-stimulated adhesion. These GMFG knockdown impaired effects could be reversed by cotransfection of GFP-tagged full-length GMFG. GMFG knockdown cells reduced the cell surface and total protein levels of α5β1-integrin and increased its degradation. Importantly, we demonstrate that GMFG mediates the ubiquitination of β1-integrin through knockdown or overexpression of GMFG. Moreover, GMFG knockdown retarded the efficient recycling of β1-integrin back to the plasma membrane following normal endocytosis of α5β1-integrin, suggesting that the involvement of GMFG in maintaining α5β1-integrin stability may occur in part by preventing ubiquitin-mediated degradation and promoting β1-integrin recycling. Furthermore, we observed that GMFG interacted with syntaxin 4 (STX4) and syntaxin-binding protein 4 (STXBP4); however, only knockdown of STXBP4, but not STX4, reduced monocyte migration and decreased β1-integrin cell surface expression. Knockdown of STXBP4 also substantially inhibited β1-integrin recycling in human monocytes. These results indicate that the effects of GMFG on monocyte migration and adhesion probably occur through preventing ubiquitin-mediated proteasome degradation of α5β1-integrin and facilitating effective β1-integrin recycling back to the plasma membrane.

Sesamin ameliorates lipopolysaccharide/d-galactosamine-induced fulminant hepatic failure by suppression of Toll-like receptor 4 signaling in mice

Sesamin has been described to exert anti-oxidant and anti-inflammatory properties. In present study, we investigated the potential effects and mechanisms of sesamin on lipopolysaccharide (LPS)-induced fulminant hepatic failure (FHF) in d-galactosamine (D-GalN)-sensitized mice. Our results showed that pretreatment with sesamin dose-dependently improved LPS/D-GalN-induced mortality and liver injury as indicated by reduced serum levels of aminotransferases and alleviated pathological damage as well as hepatocyte apoptosis in mice. Additionally, sesamin markedly attenuated LPS/D-GalN-induced adhesion molecules expression, and decreased neutrophils recruitment. Furthermore, sesamin inhibited LPS-induced tumor necrosis factor-alpha (TNF-α) production, p38 mitogen-activated protein kinases (MAPK) and NF-κB activation, and Toll like receptor (TLR) 4 expression in mice and in RAW264.7 macrophage cells. In summary, these results demonstrate that sesamin protects mice from LPS-induced FHF and the molecular mechanisms may down-regulate the expression of TLR4, block MAPK and NF-κB activation, decrease the production of TNF-α.

Susceptibility to Klebsiella pneumonaie infection in collaborative cross mice is a complex trait controlled by at least three loci acting at different time points

BACKGROUND

Klebsiella pneumoniae (Kp) is a bacterium causing severe pneumonia in immunocompromised hosts and is often associated with sepsis. With the rise of antibiotic resistant bacteria, there is a need for new effective and affordable control methods; understanding the genetic architecture of susceptibility to Kp will help in their development. We performed the first quantitative trait locus (QTL) mapping study of host susceptibility to Kp infection in immunocompetent Collaborative Cross mice (CC). We challenged 328 mice from 73 CC lines intraperitoneally with 104 colony forming units of Kp strain K2. Survival and body weight were monitored for 15 days post challenge. 48 of the CC lines were genotyped with 170,000 SNPs, with which we mapped QTLs.

RESULTS

CC lines differed significantly (P < 0.05) in mean survival time, between 1 to 15 days post infection, and broad sense heritability was 0.45. Distinct QTL were mapped at specific time points during the challenge. A QTL on chromosome 4 was found only on day 2 post infection, and QTL on chromosomes 8 and 18, only on day 8. By using the sequence variations of the eight inbred strain founders of the CC to refine QTL localization we identify several candidate genes.

CONCLUSION

Host susceptibility to Kp is a complex trait, controlled by multiple genetic factors that act sequentially during the course of infection.

Hepatoprotective effects of syringin on fulminant hepatic failure induced by D-galactosamine and lipopolysaccharide in mice

The prognosis for fulminant hepatic failure (FHF) still remains extremely poor with a high mortality and, therefore, better treatments are urgently needed. Syringin, a main active substance isolated from Eleutherococcus senticosus, has been reported to exhibit immunomodulatory and anti-inflammatory properties. In this study, we investigated the effects and underlying mechanisms of syringin on lipopolysaccharide (LPS) and D-galactosamine (D-GalN)-induced FHF in mice. Mice were administered syringin (10, 30 and 100 mg kg(-1), respectively) intraperitoneally (i.p) 30 min before LPS/D-GalN then mortality and liver injury were evaluated subsequently. We found that syringin dose-dependently attenuated LPS/D-GalN-induced FHF, as indicated by reduced mortality, inhibited aminotransferase and malondialdehyde (MDA) content, an increased glutathione (GSH) concentration and alleviated pathological liver injury. In addition, syringin inhibited LPS/D-GalN-induced hepatic caspase-3 activation and hepatocellular apoptosis, myeloperoxidase (MPO) activity and intercellular adhesion molecule-1 (ICAM-1) expression, as well as hepatic tissues tumor necrosis factor-alpha (TNF-α) production and NF-κB activation in a dose-dependent manner. These experimental data indicate that syringin might alleviate the FHF induced by LPS/D-GalN through inhibiting NF-κB activation to reduce TNF-α production.

A standardized bamboo leaf extract inhibits monocyte adhesion to endothelial cells by modulating vascular cell adhesion protein-1

Bamboo leaves (Phyllostachys pubescens Mazel ex J. Houz (Poacea)) have a long history of food and medical applications in Asia, including Japan and Korea. They have been used as a traditional medicine for centuries. We investigated the mechanism of anti-inflammatory activity of a bamboo leaf extract (BLE) on tumor necrosis factor-alpha (TNF-α)-induced monocyte adhesion in human umbilical vein endothelial cells (HUVECs). Exposure of HUVECs to BLE did not inhibit cell viability or cause morphological changes at concentrations ranging from 1 µg/ml to 1 mg/ml. Treatment with 0.1 mg/ml BLE caused 63% inhibition of monocyte adhesion in TNF-α-activated HUVECs, which was associated with 38.4% suppression of vascular cell adhesion molecule-1 expression. Furthermore, TNF-α-induced reactive oxygen species generation was decreased to 47.9% in BLE treated TNF-α-activated HUVECs. BLE (0.05 mg/ml) also caused about 50% inhibition of interleukin-6 secretion from lipopolysaccharide-stimulated monocyte. The results indicate that BLE may be clinically useful as an anti-inflammatory or anti-oxidant for human cardiovascular disease including atherosclerosis.

Polydatin Protects against Lipopolysaccharide-Induced Fulminant Hepatic Failure in D-Galactosamine-Sensitized Mice

Fulminant hepatic failure (FHF) is a devastating clinical syndrome with extremely poor prognosis and high mortality. Therefore, better treatment is urgently needed. Polydatin (PD), a traditional anti-inflammatory drug, has been described to protect against liver injury induced by certain hepatotoxins. The present study investigated the protective effect of PD against lipopolysaccharide (LPS)/D-galactosamine (D-GalN)-induced FHF in mice and the underlying mechanism. Mice were pretreated with an increasing dose of PD (10, 30, and 100 mg/kg), following LPS/D-GalN challenge. The liver injury was assessed biochemically and histologically. We found that PD exerted a protective effect on LPS/D-GalN-induced FHF as evidenced by reducing sera alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, diminishing liver histopathological injury, and lowering mortality in a dose-dependent manner. In addition, pretreatment mice with PD dose-dependently suppressed tumor necrosis factor-α (TNF-α) production, myeloperoxidase (MPO) activity, intercellular adhesion molecule-1 (ICAM-1) and endothelial cell adhesion molecule-1 (ECAM-1) expression, caspase-3 activation, and transcription factor nuclear factor-kappa B(NF-kB) activity induced by LPS. These results suggested that PD could effectively protect from LPS/D-GalN-induced FHF and the protective effect afforded by PD probably contributed to reduce TNF-α production via inhibiting NF-kB activation.

Glycomechanics of the metastatic cascade: tumor cell-endothelial cell interactions in the circulation

Hydrodynamic shear force plays an important role in the leukocyte adhesion cascade that involves the tethering and rolling of cells along the endothelial layer, their firm adhesion or arrest, and their extravasation or escape from the circulatory system by inducing passive deformation, or cell flattening, and microvilli stretching, as well as regulating the expression, distribution, and conformation of adhesion molecules on leukocytes and the endothelial layer. Similarly, the dissemination of circulating tumor cells (CTCs) from the primary tumor sites is believed to involve tethering, rolling, and firm adhesion steps before their eventual extravasation which leads to secondary tumor sites (metastasis). Of particular importance to both the leukocyte adhesion cascade and the extravasation of CTCs, glycoproteins are involved in all three steps (capture, rolling, and firm adhesion) and consist of a variety of important selectin ligands. This review article provides an overview of glycoprotein glycosylation associated with the abnormal glycan expression on cancer cell surfaces, where well-established and novel selectin ligands that are cancer related are discussed. An overview of computational approaches on the effects of fluid mechanical force on glycoprotein mediated cancer cell rolling and adhesion is presented with a highlight of recent flow-based and selectin-mediated cell capturing/enriching devices. Finally, as an important branch of the glycoprotein family, mucins, specifically MUC1, are discussed in the context of their aberrant expression on cancer cells and their role as cancer cell adhesion molecules. Since metastasis relies heavily on glycoprotein interactions in the bloodstream where the fluid shear stress highly regulates cell adhesion forces, it is important to study and understand the glycomechanics of all relevant glycoproteins (well-established and novel) as they relate to the metastatic cascade.

Physiology and pathophysiology of selectins, integrins, and IgSF cell adhesion molecules focusing on inflammation. A paradigm model on infectious endocarditis

The development of adhesion bonds, either among cells or among cells and components of the extracellular matrix, is a crucial process. These interactions are mediated by some molecules collectively known as adhesion molecules (CAMs). CAMs are ubiquitously expressed proteins playing a central role in controlling cell migration, proliferation, survival, and apoptosis. Besides their key function in physiological maintenance of tissue integrity, CAMs play an eminent role in various pathological processes such as cardiovascular disorders, atherogenesis, atherosclerotic plaque progression and regulation of the inflammatory response. CAMs such as selectins, integrins, and immunoglobulin superfamily take part in interactions between leukocyte and vascular endothelium (leukocyte rolling, arrest, firm adhesion, migration). Experimental data and pathologic observations support the assumption that pathogenic microorganisms attach to vascular endothelial cells or sites of vascular injury initiating intravascular infections. In this review a paradigm focusing on cell adhesion molecules pathophysiology and infective endocarditis development is given.

Dietary supplementation with fresh pineapple juice decreases inflammation and colonic neoplasia in IL-10-deficient mice with colitis

BACKGROUND

Bromelain, a mixture of proteolytic enzymes typically derived from pineapple stem, decreases production of proinflammatory cytokines and leukocyte homing to sites of inflammation. We previously showed that short-term oral treatment with bromelain purified from pineapple stem decreased the severity of colonic inflammation in C57BL/6 Il10(-/-) mice with chronic colitis. Since fresh pineapple fruit contains similar bromelain enzymes but at different proportions, this study aimed to determine whether long-term dietary supplementation with pineapple (supplied as juice) could decrease colon inflammation and neoplasia in Il10(-/-) mice with chronic colitis as compared with bromelain derived from stem.

METHODS

Colitis was triggered in Il10(-/-) mice by exposure to the non-steroidal anti-inflammatory drug piroxicam. Mice with colitis were supplemented with fresh vs. boiled pineapple juice or bromelain purified from stem for up to 6 months.

RESULTS

Experimental mice readily consumed fresh pineapple juice at a level that generated mean stool proteolytic activities equivalent to 14 mg bromelain purified from stem, while control mice received boiled juice with inactive enzymes. Survival was increased in the group supplemented with fresh rather than boiled juice (P = 0.01). Mice that received fresh juice also had decreased histologic colon inflammation scores and a lower incidence of inflammation-associated colonic neoplasia (35% versus 66%; P < 0.02), with fewer neoplastic lesions/colon (P = 0.05). Flow cytometric analysis of murine splenocytes exposed to fresh pineapple juice in vitro demonstrated proteolytic removal of cell surface molecules that can affect leukocyte trafficking and activation.

CONCLUSIONS

These results demonstrate that long-term dietary supplementation with fresh or unpasteurized frozen pineapple juice with proteolytically active bromelain enzymes is safe and decreases inflammation severity and the incidence and multiplicity of inflammation-associated colonic neoplasia in this commonly used murine model of inflammatory bowel disease.

Protective effect of Gö6976, a PKD inhibitor, on LPS/D: -GalN-induced acute liver injury in mice

OBJECTIVE

Protein kinase D (PKD) is a newly described serine/threonine protein kinase that plays a pivotal role in inflammatory response. In the present study, we examined the protective effect of Gö6976, a PKD inhibitor, on lipopolysaccharide (LPS) and D: -galactosamine (D: -GalN)-induced acute liver injury in mice.

MATERIALS AND METHODS

Mice were pretreated intraperitoneally with Gö6976 30 min before LPS/D: -GalN administration . The mortality and degree of hepatic injury was subsequently assessed.

RESULTS

The results indicated that LPS/D: -GalN administration markedly induced hepatic PKD activation, lethality and liver injury, while pretreatment of the PKD inhibitor Gö6976 significantly inhibited LPS-induced PKD activation, improved the survival of LPS/D: -GalN-administered mice and attenuated LPS/D: -GalN-induced liver injury, as evidenced by reduced levels of serum aminotransferases as well as reduced histopathological changes. In addition, the protective effects of Gö6976 were paralleled by suppressed activation of mitogen-activated protein kinases (MAPKs), decreased expression of tumor necrosis factor-α (TNF-α) and adhesion molecules, and reduced apoptosis and myeloperoxidase (MPO) activity in liver.

CONCLUSIONS

Our experimental data indicated that Gö6976, a PKD inhibitor, could effectively prevent LPS/D: -GalN-induced acute liver injury by inhibition of MAPKs activation to reduce TNF-α production. This suggests the potential pharmacological value of PKD inhibitors in the intervention of inflammation-based liver diseases.

Development of an active targeting liposome encapsulated with high-density colloidal gold for transmission electron microscopy

Active targeting of the liposome is an attractive strategy for drug delivery and in vivo bio-imaging. We previously reported the specific accumulation of Sialyl Lewis X (SLX) liposome to inflamed tissue in arthritic model mice or tumor-bearing mice. SLX-liposome encapsulation with fluorescent substances allows for the visualization of these liposomes by the time-dependent transvascular accumulation of fluorescent signals in the histological sections. In the present study, we developed a new SLX-liposome encapsulated with colloidal gold for transmission electron microscopic observation. We herein describe the characterization of the colloidal gold-loaded SLX-liposomes and demonstrate its specific targeting to the endothelial cells of tumor blood vessels in tumor-bearing mice.

Tetrandrine attenuates lipopolysaccharide-induced fulminant hepatic failure in D-galactosamine-sensitized mice

Fulminant hepatic failure (FHF) remains an extremely poor prognosis and high mortality; better treatments are urgently needed. Tetrandrine (TET), a traditional anti-inflammatory drug, has been reported to exhibit hepatoprotective activities in several liver injury models. We now investigated the effects and underlying mechanisms of TET on lipopolysaccharide (LPS) and D-galactosamine (D-GalN)-induced FHF in mice. TET (50, 100, and 200 mg/kg) was given intraperitoneally 1h before LPS/D-GalN injection in mice. The mortality and liver injury was evaluated subsequently. The results showed that administering TET to mice reduced mortality and improved liver injury induced by LPS/D-GalN in a dose-dependent manner. In addition, TET dose-dependently inhibited LPS/D-GalN-induced NF-kappaB activation, serum and hepatic tissues tumor necrosis factor-alpha (TNF-alpha) production, caspase-3 activation and hepatocellular apoptosis, myeloperoxidase (MPO) activity, intercellular adhesion molecule-1 (ICAM-1) and endothelial cell adhesion molecule-1 (ECAM-1) expression. Our experimental data indicated that TET might alleviate the FHF induced by LPS/D-GalN through inhibiting NF-kappaB activation to reduce TNF-alpha production.

Targeted drug-delivery approaches by nanoparticulate carriers in the therapy of inflammatory diseases

Limitations in therapy induced by adverse effects due to unselective drug availability and therefore the use of potentially too high doses are a common problem. One prominent example for this dilemma are inflammatory diseases. Colloidal carriers allow one to improve delivery of drugs to the site of action and appear promising to overcome this general therapeutic drawback. Specific uptake of nanoparticles by immune-related cells in inflamed barriers offers selective drug targeting to the inflamed tissue. Here we focus on nanocarrier-based drug delivery strategies for the treatment of common inflammatory disorders like rheumatoid arthritis, multiple sclerosis, uveitis or inflammatory bowel disease.

L-selectin: role in regulating homeostasis and cutaneous inflammation

The maintenance of immune surveillance and the generation of normal immune responses are dependent on leukocyte migration to appropriate lymphoid and non-lymphoid tissues. The process of leukocyte migration occurs through complex and highly regulated interactions between the circulating leukocytes and the vascular endothelium. Multiple families of adhesion molecules as well as specific chemoattractants and their cognate receptors function to stabilize these interactions and induce migration into the tissue. L-selectin is a key adhesion molecule that regulates both the migration of leukocytes at sites of inflammation and the recirculation of lymphocytes between blood and lymphoid tissues. L-selectin-mediated lymphocyte recirculation is required for maintaining the appropriate tissue distribution of lymphocyte subpopulations including naïve and effector subsets such as regulatory T cells. In addition, L-selectin-mediated entry into peripheral lymph nodes is required for optimal induction of lymphocyte homeostatic proliferation during lymphopenia. Importantly, L-selectin has been shown to have both adhesive and signaling functions during leukocyte migration. Specifically, L-selectin is highly efficient at capturing free-flowing leukocytes from the blood and supporting subsequent fast rolling interactions along the vascular endothelium. During rolling, synergistic interactions between L-selectin and integrin functions slow leukocyte rolling velocities allowing for chemoattractant-induced activation and eventual firm adhesion of the leukocyte to the vascular endothelium. Engagement of L-selectin by ligand generates transmembrane signals leading to activation of intracellular signaling pathways, increased integrin binding affinity, and enhanced chemotaxis. L-selectin has also been shown to mediate leukocyte recruitment during chronic inflammatory and autoimmune diseases and thus is a potential therapeutic target for drug development.

CXCR4 but not CXCR7 is mainly implicated in ocular leukocyte trafficking during ovalbumin-induced acute uveitis

Uveitis is an inflammatory ocular disease characterized by the infiltration of T lymphocytes and other leukocytes into the eye. The recruitment of these inflammatory cells from systemic vasculature to ocular tissue is a well-coordinated multistep process including rolling, firm adhesion and transmigration. CXCL12 (SDF-1alpha) is an endothelial cell-derived cytokine interacting with CXCR4 and CXCR7, two chemokine receptors mainly expressed in T cells, neutrophils and monocytes. Recent studies have shown that CXCR4, CXCR7 and their ligand, CXCL12, are important for the regulation of leukocyte mobilization and trafficking. However, it is unclear whether these two chemokine receptors are implicated in the pathogenesis of uveitis. In this study, we used DO11.10 mice, whose CD4+ T cells are genetically engineered to react with ovalbumin (OVA), to investigate the role of CXCR4 and CXCR7 in an animal model of uveitis. Intravital microscopy revealed that intravitreal OVA challenge of DO11.10 mice caused the infiltration of both T cells and neutrophils. The invasion of these inflammatory cells coincided with the detection of transcriptional up-regulation of CXCR4 and CXCR7 in the eye. In addition, both real-time-PCR and immunohistochemistry revealed an enhanced expression of endothelial CXCL12. Furthermore, intraperitoneal injection of AMD3100 (a specific CXCR4 antagonist) significantly attenuated OVA-induced uveitis and CXCL12-mediated transwell migration. In contrast, intraperitoneal administration of CXCR7 neutralizing antibody did not significantly alter ocular infiltration of inflammatory cells caused by OVA challenge. Our data suggest that CXCR4 but not CXCR7 plays a critical role in antigen-induced ocular inflammation by facilitating leukocyte infiltration. This study not only enhances our knowledge of the immunopathological mechanism of uveitis but also provides a novel rationale to target CXCR4 as an anti-inflammatory strategy to treat uveitis.

The angiopoietin-Tie2 system as a therapeutic target in sepsis and acute lung injury

BACKGROUND

Sepsis and acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) are life-threatening syndromes characterised by inflammation and increased vascular permeability. Amongst other factors, the angiopoietin-tyrosine kinase with immunoglobulin-like and EGF-like domains 2 (Tie2) system is involved.

OBJECTIVE

To explore whether the angiopoietin-Tie2 system provides suitable targets for the treatment of sepsis and ALI/ARDS.

METHODS

Original experimental and patient studies on angiopoietins and sepsis/endotoxemia, inflammation, lung injury, hyperpermeability, apoptosis, organ functions and vital outcomes were reviewed.

RESULTS/CONCLUSION

The angiopoietin-Tie2 system controls the responsiveness of the endothelium to inflammatory, hyperpermeability, apoptosis and vasoreactive stimuli. Angiopoietin-2 provokes inflammation and vascular hyperpermeability, while angiopoietin-1 has a protective effect. Targeted angiopoietin-2 inhibition with RNA aptamers or blocking antibodies is a potential anti-inflammatory and anti-vascular hyperpermeability strategy in the treatment of sepsis and ALI/ARDS.

Enteral and parenteral nutrition distinctively modulate intestinal permeability and T cell function in vitro

BACKGROUND

Nutritional support is an established element of therapy for various indications. However, its impact on the mucosal barrier function is not well understood.

AIM OF THE STUDY

We investigated the influence of EN and PN on intestinal epithelial cells and peripheral blood (PBMC) and lamina propria mononuclear cells (LPMC), all of which are involved in the mucosal defense against bacterial translocation and systemic inflammation.

METHODS

Integrity of epithelial cells was measured as transepithelial electrical resistance (TER) of confluent Caco-2 monolayers in the presence of 1% EN, PN and a parenteral amino acid mixture (AM). To determine wound healing capacities, an established migration model with IEC-6 cells was used. Furthermore, we investigated apoptosis, cell activation, proliferation and cytokine secretion of Caco-2, HT29 and of stimulated PBMC and LPMC cultured with or without 1 and 5% EN, AM or PN.

RESULTS

We demonstrated that EN, AM and PN promoted the integrity of the epithelial monolayer and reconstituted epithelial cell continuity TGF-beta-dependently and -independently. Interestingly, only PN induced apoptosis and decreased the mitochondrial membrane potential. The activation status of PBMC was significantly reduced by EN and AM. Specifically, EN leads to an increased apoptosis rate, inhibited cell cycle progression and increased pro-inflammatory cytokine secretion. Both EN and PN reduced the activation status and the release of pro- and anti-inflammatory cytokines.

CONCLUSIONS

Our study provides evidence that by promoting wound healing and regulating T cell function, EN, AM, and PN potently interact with the intestinal barrier and immune system, thus justifying its use in diseases accompanied by impaired mucosal barrier function.

Vessel-specific Toll-like receptor profiles in human medium and large arteries

BACKGROUND

Inflammatory vasculopathies, ranging from the vasculitides (Takayasu arteritis, giant cell arteritis, and polyarteritis nodosa) to atherosclerosis, display remarkable target tissue tropisms for selected vascular beds. Molecular mechanisms directing wall inflammation to restricted anatomic sites within the vascular tree are not understood. We have examined the ability of 6 different human macrovessels (aorta and subclavian, carotid, mesenteric, iliac, and temporal arteries) to initiate innate and adaptive immune responses by comparing pathogen-sensing and T-cell-stimulatory capacities.

METHODS AND RESULTS

Gene expression analysis for pathogen-sensing Toll-like receptors (TLRs) 1 to 9 showed vessel-specific profiles, with TLR2 and TLR4 ubiquitously present, TLR7 and TLR9 infrequent, and TLR1, TLR3, TLR5, TLR6, and TLR8 expressed in selective patterns. Experiments with vessel walls stripped of the intimal or adventitial layer identified dendritic cells at the media-adventitia junction as the dominant pathogen sensors. In human artery-severe combined immunodeficiency (SCID) mouse chimeras, adoptively transferred human T cells initiated vessel wall inflammation if wall-embedded dendritic cells were conditioned with TLR ligands. Wall-infiltrating T cells displayed vessel-specific activation profiles with differential production of CD40L, lymphotoxin-alpha, and interferon-gamma. Vascular bed-specific TLR fingerprints were functionally relevant, as exemplified by differential responsiveness of iliac and subclavian vessels to TLR5 but not TLR4 ligands.

CONCLUSIONS

Populated by indigenous dendritic cells, medium and large human arteries have immune-sensing and T-cell-stimulatory functions. Each vessel in the macrovascular tree exhibits a distinct TLR profile and supports selective T-cell responses, imposing vessel-specific risk for inflammatory vasculopathies.

T lymphocyte migration to lymph nodes is maintained during homeostatic proliferation

The immune system maintains appropriate cell numbers through regulation of cell proliferation and death. Normal tissue distribution of lymphocytes is maintained through expression of specific adhesion molecules and chemokine receptors such as L-selectin and CCR7, respectively. Lymphocyte insufficiency or lymphopenia induces homeostatic proliferation of existing lymphocytes to increase cell numbers. Interestingly, homeostatic proliferation of T lymphocytes induces a phenotypic change from naïve- to memory-type cell. Naïve T cells recirculate between blood and lymphoid tissues whereas memory T cells migrate to nonlymphoid sites such as skin and gut. To assess effects of homeostatic proliferation on migratory ability of T cells, a murine model of lymphopenia-induced homeostatic proliferation was used. Carboxyfluorescein diacetate, succinimidyl ester-labeled wild-type splenocytes were adoptively transferred into recombination activation gene-1-deficient mice and analyzed by flow cytometry, in vitro chemotactic and in vivo migration assays, and immunofluorescence microscopy. Homeostatically proliferated T cells acquired a mixed memory-type CD44high L-selectinhigh CCR7low phenotype. Consistent with this, chemotaxis to secondary lymphoid tissue chemokine in vitro was reduced by 22%-34%. By contrast, no differences were found for migration or entry into lymph nodes during in vivo migration assays. Therefore, T lymphocytes that have undergone homeostatic proliferation recirculate using mechanisms similar to naïve T cells.

Bromelain treatment decreases neutrophil migration to sites of inflammation

Bromelain, a mixture of proteases derived from pineapple stem, has been reported to have therapeutic benefits in a variety of inflammatory diseases, including murine inflammatory bowel disease. The purpose of this work was to understand potential mechanisms for this anti-inflammatory activity. Exposure to bromelain in vitro has been shown to remove a number of cell surface molecules that are vital to leukocyte trafficking, including CD128a/CXCR1 and CD128b/CXCR2 that serve as receptors for the neutrophil chemoattractant IL-8 and its murine homologues. We hypothesized that specific proteolytic removal of CD128 molecules by bromelain would inhibit neutrophil migration to IL-8 and thus decrease acute responses to inflammatory stimuli. Using an in vitro chemotaxis assay, we demonstrated a 40% reduction in migration of bromelain- vs. sham-treated human neutrophils in response to rhIL-8. Migration to the bacterial peptide analog fMLP was unaffected, indicating that bromelain does not induce a global defect in leukocyte migration. In vivo bromelain treatment generated a 50-85% reduction in neutrophil migration in 3 different murine models of leukocyte migration into the inflamed peritoneal cavity. Intravital microscopy demonstrated that although in vivo bromelain treatment transiently decreased leukocyte rolling, its primary long-term effect was abrogation of firm adhesion of leukocytes to blood vessels at the site of inflammation. These changes in adhesion were correlated with rapid re-expression of the bromelain-sensitive CD62L/L-selectin molecules that mediate rolling following in vivo bromelain treatment and minimal re-expression of CD128 over the time period studied. Taken together, these studies demonstrate that bromelain can effectively decrease neutrophil migration to sites of acute inflammation and support the specific removal of the CD128 chemokine receptor as a potential mechanism of action.

Purified polysaccharide from Ginkgo biloba leaves inhibits P-selectin-mediated leucocyte adhesion and inflammation

AIM

To investigate the anti-inflammatory mechanism of the polysaccharides of Ginkgo biloba leaves (PGBL) by inhibiting leucocyte adhesion.

METHODS

The rough PGBL were isolated and purified. The anti-inflammatory effects of purified PGBL (p-PGBL) were assayed by ear edema induced by xylol and the acute peritonitis model in mice. The effect of p-PGBL on inhibiting the interaction between P-selectin and its ligands was investigated by flow cytometry and flow chamber.

RESULTS

p-PGBL could effectively inhibit the acute inflammation in mice and interfere with the adhesion of HL-60 cells, a human leukaemia cell line, or neutrophils to P-selectin in static conditions, as well as the adhesion of neutrophils to Chinese hamster ovary cells expressing human P-selectin and human umbilical vein endothelial cells in flow conditions in a dose-dependant manner.

CONCLUSIONS

p-PGBL can inhibit the inflammatory process through interfering with the interaction between P-selectin and its ligands.

Aggravation of different types of experimental colitis by depletion or adhesion blockade of neutrophils

BACKGROUND & AIMS

Neutrophils are generally thought to play an important proinflammatory role in the pathogenesis of inflammatory bowel disease. The objective of this study was to evaluate whether blocking the invasion of neutrophils by anti-L-selectin monoclonal antibodies modulates chemically induced colitis and how this modulation is accomplished.

METHODS

Trinitrobenzene sulfonic acid/dinitrobenzene sulfonic acid (TNBS/DNBS)-induced colitis was studied in rats on treatment with anti-L-selectin monoclonal antibodies (mAb) or antineutrophil antiserum. Different anti-L-selectin mAb, either blocking or nonblocking, as well as F(ab)(2) fragments were evaluated. Additionally, leukocyte migration was examined using intravital microscopy. Furthermore, the effect of neutrophil depletion in rat TNBS-induced colitis was studied either prior to or after colitis induction as well as murine CD4(+)CD45RB(high) transfer colitis. Finally, bacterial translocation during DNBS-induced colitis was studied in neutrophil-depleted and control rats.

RESULTS

Anti-L-selectin mAb treatment resulted in increased mortality and bowel inflammation as well as hemorrhagic eye secretion. No clear difference was found between blocking and nonblocking mAb or F(ab)(2) fragments. For all investigated antibodies/fragments, either complete blockade of leukocyte invasion or marked neutrophil depletion was found. Accordingly, neutrophil depletion by antiserum resulted in aggravation of rat DNBS-induced colitis as well as murine transfer colitis.

CONCLUSIONS

Adhesion blockade or neutrophil depletion aggravates rat TNBS/DNBS-induced colitis together with extraintestinal manifestations of the eyes. Therefore, neutrophils appear to have an important role in mucosal repair processes. Importantly, adhesion blockade as a therapeutic concept can be detrimental in inflammatory bowel disease.

Migratory Pathways of T Cells and Response to CXCR3 and CXCR4 Ligands: Adhesion Molecules Involved and Implications for Multiple Sclerosis Pathogenesis

Gammadelta T lymphocytes are thought to be involved in multiple sclerosis (MS) pathogenesis. In this work, we discuss the characteristics of these cells and possible implications in the pathogenesis of MS, focusing on the mechanism(s) underlying extravasation and tissue localization. Phenotype and transendothelial migration of gammadelta T cells from healthy donors and patients with relapsing-remitting MS were studied. In MS patients the V delta 2 T cell subset, expressing NKRP1A/CD161 adhesion molecule, is expanded and capable of transendothelial migration. V delta 1/V delta 2 subsets use distinct signal transduction pathways: V delta 1 cells lack NKRP1A and express PECAM-1/CD31, which drives transmigration, while V delta 2 cells are PECAM-1 negative and use NKRP1A. V delta 2 migration is coupled with CAMKII, whereas V delta 1 depend on PI-3K. NKRP1A and PECAM-1 selectively activate the two pathways: indeed, oligomerization of NKRP1A on V delta 2 T cells leads to CAMKII activation, occupancy of PECAM-1 on V delta 1 cells triggers the PI-3K-dependent Akt/PKB pathway. Moreover, V delta 2 T cells are CXCR3(bright)CXCR4(dull), while V delta 1 are mostly CXCR4(+). V delta 1 and V delta 2 cells transmigrate in response to IP-10/CXCL10 and SDF-1/CXCL12 according to the expression of their specific receptors. In a fraction of V delta 1 T cells coexpressing CXCR3 and CXCR4, the homeostatic chemokine 6Ckine/SLC/CCL21 is more effective. IP-10/CXCL10 or 6Ckine/SLC/CCL21 and SDF-1/CXCL12-induced transmigration is coupled to PI-3K/Akt/PKB, but only CXCR3 is capable of inducing CAMKII activation. We suggest that both subsets of gammadelta T lymphocytes may migrate to the site of lesion in MS using two different signaling pathways to extravasate and responding to different chemokines.

Wnt signaling induces matrix metalloproteinase expression and regulates T cell transmigration

Wnts are a family of secreted glycoproteins with diverse developmental roles, including regulation of cell migration; however, little is known about wnt signaling in mature T cells. We find that endothelial-cell-derived wnts, acting through Frizzled receptors, induce matrix metalloproteinase (MMP) 2 and MMP9 expression in effector T cells. Blocking wnt signaling, or MMP activity, reduces T cell migration through the basement membrane in vitro and into inflamed skin in vivo. Wnt signaling stabilizes beta-catenin protein in T cells and directly targets the MMP promoters through tandem TCF sites. Thus, our data support a necessary and previously unexpected role for wnt signaling in T cell extravasation.

Dynamic adhesion of T lymphocytes to endothelial cells revealed by atomic force microscopy

The recruitment of T lymphocytes to lymphoid organs or sites of inflammation is a crucial step in adaptive immunity. These processes require endothelial activation and expression of adhesion molecules, including E- and P-selectins, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1). However, the complete characterization of the adhesion strength and dynamics between lymphocytes and endothelial cells has been hampered by the lack of sensitive quantitative techniques. Here we report on the application of atomic force microscopy to characterize the interaction between individual pairs of living T lymphocytes (i.e., Jurkat cells) and human umbilical vein endothelial cells (HUVECs). The detachment of individual cell-cell conjugates was a complex process involving several step-like rupture events and the viscoelastic deformation of cells on the scale of several microns. Adhesion between Jurkat cells and activated endothelial cells increased with compression force and contact time, with the most dramatic changes occurring within the first half second of contact. After 0.25 sec of contact, E-selectin, ICAM-1, and VCAM-1 contributed to 18%, 39%, and 41% of total adhesion strength, respectively, suggesting that ICAM-1 and VCAM-1 contributed more than the selectins in supporting cell attachment.

Human cytomegalovirus (HCMV) infection of endothelial cells promotes naive monocyte extravasation and transfer of productive virus to enhance hematogenous dissemination of HCMV

Human cytomegalovirus (HCMV) pathogenesis is dependent on the hematogenous spread of the virus to host tissue. While data suggest that infected monocytes are required for viral dissemination from the blood to the host organs, infected endothelial cells are also thought to contribute to this key step in viral pathogenesis. We show here that HCMV infection of endothelial cells increased the recruitment and transendothelial migration of monocytes. Infection of endothelial cells promoted the increased surface expression of cell adhesion molecules (intercellular cell adhesion molecule 1, vascular cell adhesion molecule 1, E-selectin, and platelet endothelial cell adhesion molecule 1), which were necessary for the recruitment of naïve monocytes to the apical surface of the endothelium and for the migration of these monocytes through the endothelial cell layer. As a mechanism to account for the increased monocyte migration, we showed that HCMV infection of endothelial cells increased the permeability of the endothelium. The cellular changes contributing to the increased permeability and increased naïve monocyte transendothelial migration include the disruption of actin stress fiber formation and the decreased expression of lateral junction proteins (occludin and vascular endothelial cadherin). Finally, we showed that the migrating monocytes were productively infected with the virus, documenting that the virus was transferred to the migrating monocyte during passage through the lateral junctions. Together, our results provide evidence for an active role of the infected endothelium in HCMV dissemination and pathogenesis.

Short-term hyperthermia prevents activation of proinflammatory genes in fibroblast-like synoviocytes by blocking the activation of the transcription factor NF-κB

Fibroblast-like synoviocytes (FLS) play a key role in the genesis of rheumatoid arthritis (RA). FLS are among the most versatile cells with the potential to activate an array of genes that are able to initiate and propagate inflammation in RA-affected joints. Controlling activation of FLS might hold the key to restraining inflammation in RA-affected joints. In this study, we investigate the effect and mechanisms of short-term hyperthermia on a series of proinflammatory genes in FLS. In vitro experiments demonstrate that exposure of FLS to elevated temperatures for the duration of 30 min prevents activation of a series of genes with proinflammatory properties. Exposure to hyperthermia reduces IL-1beta-induced prostaglandin E2 release, suppresses activation of the adhesion molecules VCAM-1, ICAM-1, the cytokines TNFalpha, IL-1alpha, IL-1beta, IL-8 as well as COX-2 protein synthesis. Real time reverse transcriptase-polymerase chain reaction showed that hyperthermia altered gene expression at the transcriptional level. The amount and the duration of inhibition is gene-specific and lasts for up to 25 h. As to the mechanism of inhibition, electrophoretic mobility shift assay experiments demonstrated that exposure of FLS to hyperthermia prevents IL-1beta-induced NF-kappaB translocation and subsequent DNA binding. Many mechanisms have been shown to be involved in hyperthermia-mediated effects on NF-kappaB-DNA interactions. We demonstrate by Western blot experiments that in FLS, hyperthermia prevents the phosphorylation and subsequent degradation of IkappaBalpha, therefore retaining the NF-kappaB complex in the cytoplasm. Carefully controlled in vivo tests are certainly needed before one can take full advantage of those phenomena; however, the ease by which the temperature in joints can be modulated might offer an opportunity for manipulating inflammatory processes in joints by simple balneological means.

Evidence of a Functional Role for Interaction between ICAM-1 and Nonmuscle α-Actinins in Leukocyte Diapedesis

ICAM-1 is involved in both adhesion and extravasation of leukocytes to endothelium during inflammation. It has been shown that the ICAM-1 cytoplasmic domain is important for transendothelial migration of leukocytes but the precise molecular mechanisms involving the intracytoplasmic portion of ICAM-1 is not known. To characterize precisely the molecular scaffolding associated with ICAM-1, we have used the yeast two-hybrid system, and we have identified six different proteins interacting with the ICAM-1 cytoplasmic domain. In this study, we report that the two forms of nonmuscle alpha-actinin (i.e., alpha-actinin 1 and alpha-actinin 4) associate with ICAM-1, and that these interactions are essential for leukocyte extravasation. These interactions were further confirmed by coimmunoprecipitation and immunofluorescence in endothelial cells and in ICAM-1-transfected Chinese hamster ovary cells. The function of these interactions was analyzed by point mutation of charged amino acids located on ICAM-1 cytoplasmic domain. We have identified three charged amino acids (arginine 480, lysine 481, and arginine 486) which are essential in the binding of alpha-actinins to the ICAM-1 cytoplasmic tail. Mutation of these amino acids completely inhibited ICAM-1-mediated diapedesis. Experiments with siRNA inhibiting specifically alpha-actinin 1 or alpha-actinin 4 on endothelial cells indicated that alpha-actinin 4 had a major role in this phenomenon. Thus, our data demonstrate that ICAM-1 directly interacts with cytoplasmic alpha-actinin 1 and 4 and that this interaction is required for leukocyte extravasation.

The influence of various structural parameters of semisynthetic sulfated polysaccharides on the P-selectin inhibitory capacity

Selectin-mediated leukocyte rolling along the endothelium is of key importance for maintaining the cellular immune response. The anti-inflammatory activities of heparin have partly been related to inhibition of P-selectin binding. Heparin, however, suffers from its heterogeneous variable structure, the animal origin and multiple in vivo effects. As P-selectin is a promising target for anti-inflammatory approaches, we focused on P-selectin inhibition by other sulfated polysaccharides and compared them with six heparins. We examined 15 structurally defined semisynthetic sulfated glucans, non-animal-derived from the linear glucans phycarin, curdlan or pullulan. The derivatives gradually differ in their degree of sulfation, molecular weight, and glycosidic linkage. The inhibitory capacity was analysed in a parallel plate flow chamber, detecting the rolling of U937 cells on P-selectin layers. Unfractionated heparins displayed variabilities between different preparations. Considering fractionated heparins, exceeding of a minimal mass is essential for activity. Comparing the glucan sulfates, charge density is the most important parameter for P-selectin binding. Highly sulfated derivatives are excellent inhibitors, the reduced cell binding up to 16.2+/-6.4% strongly exceeded the heparin activities. Molecular weight is of minor effects, while glycosidic backbone linkage holds certain importance. To check the P-selectin inhibition in vivo, heparin and one phycarin sulfate were tested using intravital microscopy of microvasculature in mice. Both compounds significantly reduced the rolling fractions of activated platelets on endothelium as effective as a blocking P-selectin antibody. Our study indicates that semisynthetic glucan sulfates with optimal structures block P-selectin excellently and might become promising candidates for anti-inflammatory drugs to replace heparin for certain applications.

The replacement of graft endothelium by recipient-type cells conditions allograft rejection mediated by indirect pathway CD4(+) T cells

BACKGROUND

Whereas the participation of alloreactive T cells sensitized by indirect allorecognition in graft rejection is well documented, the nature of recipient antigen presenting cells recognized by indirect pathway CD4(+) T cells within the graft has yet to be identified. The purpose of this study was to determine the role played by graft endothelium replacement in the immune recognition of cardiac allografts rejected by indirect pathway CD4(+) T cells.

METHODS

Transgenic RAG2(-/-) mice expressing I-A(b)-restricted male antigen H-Y-specific TcR were studied for their capacity to reject H-2(k) male cardiac allografts. Chronic vascular rejection in this model was due to the indirect recognition of H-Y antigen shed from H-2(k) male allograft and presented by the recipient's own I-A(b) APC to transgenic T cells.

RESULTS

Immunohistochemical analysis of rejected grafts revealed the presence of numerous microvascular endothelial cells (EC) that expressed recipient's I-A MHC class II molecules. This observation suggested that graft endothelium replacement by I-A(b)-positive cells of recipient origin could stimulate the rejection of male H-2(k) graft by I-A(b)--restricted H-Y--specific T cells. To investigate further this possibility, hearts from H-2(b)--into--H-2(k) irradiation bone marrow (BM) chimera were transplanted in transgenic recipients. A direct correlation was observed between the presence of I-A(b)-positive EC within myocardial microvessels and the induction of acute rejection of chimeric H-2(k) male cardiac allografts transplanted in transgenic recipients.

CONCLUSIONS

We conclude that graft endothelium replacement by recipient-type cells is required for the rejection of cardiac allograft mediated by indirect pathway alloreactive CD4(+) T cells.

Assessment of a bioactive compound for its potential antiinflammatory property by tight junction permeability

Lactobacillus probiotic strains are proving to be abundant sources of bioactive components, including antiinflammatory components. Lifree was made of fruits fermented by Lactobacillus paracasei, Lactobacillus reuterrii and Saccharomyces cerevisiae. This study was designed to test these compounds in cell assays measuring epithelial barrier function and proliferation in the first instance. Cell proliferation was measured in mouse fibroblasts cells (3T3NIH) and rat intestinal epithelial cells (IEC-6), and tight junction activity in the kidney epithelial cell line (MDCK). Tight junction permeability was assessed by measuring transepithelial electrical resistance (TER) across confluent monolayers, following the addition of Lifree with or without a challenge with EGTA. Lifree promoted tight junction formation and recovery following loss of TER from challenge with EGTA. On the other hand, Lifree did not stimulate cell growth in either 3T3NIH and IEC-6 cells. Lifree stimulates tight junction maintenance and formation, suggesting it may have potential antiinflammatory properties.

Effect of in vivo phenol or hydroquinone exposure on events related to neutrophil delivery during an inflammatory response

Phenol (PHE) and hydroquinone (HQ) are metabolites of benzene that affect leukocytes after solvent intoxication. Hence, we investigated the effects of PHE or HQ exposure on neutrophil mobilization during an inflammatory response. Male Wistar rats received intraperitoneal injections of PHE, HQ or vehicle only and assays were performed 24 h after the last dose. Quantifications of bone marrow or circulating leukocytes showed that only HQ exposure induced neutrophilia, probably due to the accelerated mobilization from the bone marrow compartment, since reduced numbers of segmented cells in the last phase of maturation were detected there. Intravital microscopy showed that circulating leukocytes of HQ-exposed rats increased their rolling behavior and adherence to the mesenteric postcapillary venule wall in vivo. The enhanced leukocyte-endothelium interaction was not dependent on microvascular reactivity or perivascular mast cell degranulation. Instead, it was the result of neutrophil activation, demonstrated by a decrease in L-selectin and an increase in beta2 integrin expression on neutrophil membranes. This pattern of neutrophil activation may have contributed to the higher number of neutrophils in the subcutaneous inflammatory response of HQ-exposed rats after oyster glycogen injection. Taken together, our results indicate that HQ exposure alters neutrophil mobilization, which results in an exacerbated response after an injury. Although PHE is endogenously metabolized to HQ, PHE exposure only induced an increment in rolling behavior, which was not sufficient to alter the inflammatory response.

Cell biology of T cell activation and differentiation

T cells are major components of the adaptive immune system. They can differentiate into two different populations of effector cells-type one and type two-and may also become tolerant. T cells respond to immune challenges by interacting with antigen-presenting cells of the innate immune system. These latter cells can identify the nature of any immune challenge and initiate adaptive immune responses. Dendritic cells are the most important antigen-presenting cells in the body. The T cell recognizes both peptides associated with MHC molecules on the antigen-presenting cells and also other molecules in a complex structure known as an immunological synapse. The nature of the antigen, the cytokine environment, and other molecules on the dendritic cell surface instruct the T cells as to the response required. A better understanding of the biology of T cell responses offers the prospect of more effective therapeutic interventions.

Soluble intracellular adhesion molecule-1 is associated with cardiovascular disease risk and mortality in older adults

BACKGROUND

Intracellular adhesion molecule-1 (ICAM-1) regulates leukocyte-endothelial attachment, a process crucial to atherosclerosis. Circulating soluble ICAM-1 (sICAM-1) may serve as a marker of cardiovascular disease (CVD) progression.

OBJECTIVES

We examined the association of sICAM-1 with measures of subclinical CVD and risk of incident CVD events and death in older men and women (age > or = 65 years) from the Cardiovascular Health Study.

METHODS

Selected participants were free of clinical CVD at baseline. Non-exclusive incident case groups were angina (n = 534), myocardial infarction (n = 304), stroke (n = 327), and death (n = 842; CVD death = 310). A total 643 subjects were free of events during follow-up.

RESULTS

sICAM-1 was positively associated with C-reactive protein, interleukin-6 and fibrinogen and measures of subclinical CVD in these older men and women. In Cox regression models adjusted for age, gender, and race, increasing levels of sICAM-1 were associated with increased risk of all cause mortality in men and women. Hazard ratios (95% confidence intervals) for a one standard deviation increase in sICAM-1 (89.7 ng mL(-1)) were 1.3 (1.1-1.4) in men and 1.2 (1.1-1.3) in women. sICAM-1 was associated with increased risk of CVD death in women (1.2; 1.0-1.5), but not men (1.1; 0.9-1.3). There were no associations of sICAM-1 with non-fatal CVD events.

CONCLUSIONS

While sICAM-1 was associated with death in older men and women, there was a more marked association between sICAM-1 and CVD death in women.