PECAM-1 (CD 31) mediates transendothelial leukocyte migration in experimental colitis

Key Disease-Related Genes and Immune Cell Infiltration Landscape in Inflammatory Bowel Disease: A Bioinformatics Investigation

Inflammatory Bowel Diseases (IBD), which encompass ulcerative colitis (UC) and Crohn's disease (CD), are characterized by chronic inflammation and tissue damage of the gastrointestinal tract. This study aimed to uncover novel disease-gene signatures, dysregulated pathways, and the immune cell infiltration landscape of inflamed tissues. Eight publicly available transcriptomic datasets, including inflamed and non-inflamed tissues from CD and UC patients were analyzed. Common differentially expressed genes (DEGs) were identified through meta-analysis, revealing 180 DEGs. DEGs were implicated in leukocyte transendothelial migration, PI3K-Akt, chemokine, NOD-like receptors, TNF signaling pathways, and pathways in cancer. Protein-protein interaction network and cluster analysis identified 14 central IBD players, which were validated using eight external datasets. Disease module construction using the NeDRex platform identified nine out of 14 disease-associated genes (CYBB, RAC2, GNAI2, ITGA4, CYBA, NCF4, CPT1A, NCF2, and PCK1). Immune infiltration profile assessment revealed a significantly higher degree of infiltration of neutrophils, activated dendritic cells, plasma cells, mast cells (resting/activated), B cells (memory/naïve), regulatory T cells, and M0 and M1 macrophages in inflamed IBD tissue. Collectively, this study identified the immune infiltration profile and nine disease-associated genes as potential modulators of IBD pathogenesis, offering insights into disease molecular mechanisms, and highlighting potential disease modulators and immune cell dynamics.

Differential Impact of Smoking on Methylome and Transcriptome in Crohn's Disease and Ulcerative Colitis

BACKGROUND

Smoking is an environmental factor that differentially impacts Crohn's disease (CD) and ulcerative colitis (UC). The mechanism of impact of smoking on disease risk and clinical outcomes remains to be established.

METHODS

This study used a prospective cohort of patients with CD or UC. Self-reported smoking status was validated using serum cotinine measurement. We profiled methylation changes in peripheral blood using the Illumina Methylation BeadChip. Transcriptomic profiling was performed on ileal and colonic tissue using an Illumina TruSeq platform. We compared the methylation and transcriptional changes in current, former, and never smokers stratified by disease type.

RESULTS

Our cohort included 200 patients with CD or UC with methylation profiles and 160 with transcriptomic data. The mean serum cotinine level was higher in current compared with former or never smokers. Epigenetic changes common to both CD and UC included hypomethylation at AHRR. Smoking-associated MGAT3 hypomethylation was associated with severe disease course only in UC, while IER3 hypomethylation was associated with worse course only in CD. Smoking downregulated several inflammatory pathways in UC. Current smoking in CD but not in UC was associated with upregulation of several genes mediating Paneth cell function. Genes with opposite direction of effects in CD and UC include HSD3B2 and GSTA1.

CONCLUSIONS

Our findings suggest both common and differential effects of cigarette smoking on CD and UC. Paneth cell dysfunction may mediate adverse impact of smoking on CD. Bile acid and oxidative stress pathways may be relevant for the differential effect of smoking on CD and UC.

Differential Effects of Ontamalimab Versus Vedolizumab on Immune Cell Trafficking in Intestinal Inflammation and Inflammatory Bowel Disease

BACKGROUND AND AIMS

The anti-MAdCAM-1 antibody ontamalimab demonstrated efficacy in a phase II trial in ulcerative colitis and results of early terminated phase III trials are pending, but its precise mechanisms of action are still unclear. Thus, we explored the mechanisms of action of ontamalimab and compared it to the anti-α4β7 antibody vedolizumab.

METHODS

We studied MAdCAM-1 expression with RNA sequencing and immunohistochemistry. The mechanisms of action of ontamalimab were assessed with fluorescence microscopy, dynamic adhesion and rolling assays. We performed in vivo cell trafficking studies in mice and compared ontamalimab and vedolizumab surrogate [-s] antibodies in experimental models of colitis and wound healing. We analysed immune cell infiltration under anti-MAdCAM-1 and anti-α4β7 treatment by single-cell transcriptomics and studied compensatory trafficking pathways.

RESULTS

MAdCAM-1 expression was increased in active inflammatory bowel disease. Binding of ontamalimab to MAdCAM-1 induced the internalization of the complex. Functionally, ontamalimab blocked T cell adhesion similar to vedolizumab, but also inhibited L-selectin-dependent rolling of innate and adaptive immune cells. Despite conserved mechanisms in mice, the impact of ontamalimab-s and vedolizumab-s on experimental colitis and wound healing was similar. Single-cell RNA sequencing demonstrated enrichment of ontamalimab-s-treated lamina propria cells in specific clusters, and in vitro experiments indicated that redundant adhesion pathways are active in these cells.

CONCLUSIONS

Ontamalimab has unique and broader mechanisms of action compared to vedolizumab. However, this seems to be compensated for by redundant cell trafficking circuits and leads to similar preclinical efficacy of anti-α4β7 and anti-MAdCAM-1 treatment. These results will be important for the interpretation of pending phase III data.

Genetically Engineered-Cell-Membrane Nanovesicles for Cancer Immunotherapy

The advent of immunotherapy has marked a new era in cancer treatment, offering significant clinical benefits. Cell membrane as drug delivery materials has played a crucial role in enhancing cancer therapy because of their inherent biocompatibility and negligible immunogenicity. Different cell membranes are prepared into cell membrane nanovesicles (CMNs), but CMNs have limitations such as inefficient targeting ability, low efficacy, and unpredictable side effects. Genetic engineering has deepened the critical role of CMNs in cancer immunotherapy, enabling genetically engineered-CMN (GCMN)-based therapeutics. To date, CMNs that are surface modified by various functional proteins have been developed through genetic engineering. Herein, a brief overview of surface engineering strategies for CMNs and the features of various membrane sources is discussed, followed by a description of GCMN preparation methods. The application of GCMNs in cancer immunotherapy directed at different immune targets is addressed as are the challenges and prospects of GCMNs in clinical translation.

CD31 as a probable responding and gate-keeping protein of the blood-brain barrier and the risk of Alzheimer's disease

Several studies have shown that an abnormal vascular-immunity link could increase Alzheimer's disease (AD) risk; however, the mechanism is unclear. CD31, also named platelet endothelial cell adhesion molecule (PECAM), is a surface membrane protein of both endothelial and immune cells and plays important roles in the interaction between the vascular and immune systems. In this review, we focus on research regarding CD31 biological actions in the pathological process that may contribute to AD based on the following rationales. First, endothelial, leukocyte and soluble forms of CD31 play multi-roles in regulating transendothelial migration, increasing blood-brain barrier (BBB) permeability and resulting in neuroinflammation. Second, CD31 expressed by endothelial and immune cells dynamically modulates numbers of signaling pathways, including Src family kinases, selected G proteins, and β-catenin which in turn affect cell-matrix and cell-cell attachment, activation, permeability, survival, and ultimately neuronal cell injury. In endothelia and immune cells, these diverse CD31-mediated pathways act as a critical regulator in the immunity-endothelia-brain axis, thereby mediating AD pathogenesis in ApoE4 carriers, which is the major genetic risk factor for AD. This evidence suggests a novel mechanism and potential drug target for CD31 in the background of genetic vulnerabilities and peripheral inflammation for AD development and progression.

Contribution of Blood Vessel Activation, Remodeling and Barrier Function to Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBDs) consist of a group of chronic inflammatory disorders with a complex etiology, which represent a clinical challenge due to their often therapy-refractory nature. In IBD, inflammation of the intestinal mucosa is characterized by strong and sustained leukocyte infiltration, resulting in the loss of epithelial barrier function and subsequent tissue destruction. This is accompanied by the activation and the massive remodeling of mucosal micro-vessels. The role of the gut vasculature in the induction and perpetuation of mucosal inflammation is receiving increasing recognition. While the vascular barrier is considered to offer protection against bacterial translocation and sepsis after the breakdown of the epithelial barrier, endothelium activation and angiogenesis are thought to promote inflammation. The present review examines the respective pathological contributions of the different phenotypical changes observed in the microvascular endothelium during IBD, and provides an overview of potential vessel-specific targeted therapy options for the treatment of IBD.

Vascular alterations impede fragile tolerance to pregnancy in type 1 diabetes

OBJECTIVE

To determine the impact of autoimmunity in the absence of glycemic alterations on pregnancy in type 1 diabetes (T1D).

DESIGN

Because nonobese diabetic (NOD) mice experience autoimmunity before the onset of hyperglycemia, we studied pregnancy outcomes in prediabetic NOD mice using flow cytometry and enzyme-linked immunosorbent assays. Once we determined that adverse events in pregnancy occurred in euglycemic mice, we performed an exploratory study using electronic health records to better understand pregnancy complications in humans with T1D and normal hemoglobin A1c levels.

SETTING

University Medical Center.

PATIENT(S)/ANIMAL(S)

Nonobese diabetic mice and electronic health records from Vanderbilt University Medical Center.

INTERVENTION(S)

Nonobese diabetic mice were administered 200 μg of an anti-interleukin 6 (IL-6) antibody every other day starting on day 5 of gestation.

MAIN OUTCOME MEASURE(S)

Changes in the number of abnormal and reabsorbed pups in NOD mice and odds of vascular complications in pregnancy in T1D in relation to A1c.

RESULT(S)

Prediabetic NOD mice had increased adverse pregnancy outcomes compared with nonautoimmune mice; blockade of IL-6, which was secreted by endothelial cells, decreased the number of reabsorbed and abnormal fetuses. Similarly, vascular complications were increased in pregnant patients with T1D across all A1c values.

CONCLUSION(S)

The vascular secretion of IL-6 drives adverse pregnancy outcomes in prediabetic NOD mice. Pregnant patients with T1D have increased vascular complications even with normal hemoglobin A1cs, indicating a potential effect of autoimmunity on the placental vasculature.

Platelet endothelial cell adhesion molecule-1 is a gatekeeper of neutrophil transendothelial migration in ischemic stroke

RATIONALE

Adhesion molecules are key elements in stroke-induced brain injury by regulating the migration of effector immune cells from the circulation to the lesion site. Platelet endothelial cell adhesion molecule-1 (PECAM-1) is an adhesion molecule highly expressed on endothelial cells and leukocytes, which controls the final steps of trans-endothelial migration. A functional role for PECAM-1 in post-ischemic brain injury has not yet been demonstrated.

OBJECTIVE

Using genetic Pecam-1 depletion and PECAM-1 blockade using a neutralizing anti-PECAM-1 antibody, we evaluated the role of PECAM-1 mediated trans-endothelial immune cell migration for ischemic injury, delayed brain atrophy, and brain immune cell infiltrates. Trans-endothelial immune cell migration was furthermore evaluated in cultured human cerebral microvascular endothelial cells.

METHODS AND RESULTS

Transient middle cerebral artery occlusion (tMCAO) was induced in 10-12-week-old male Pecam-1^-/- and Pecam-1^+/+ wildtype mice. PECAM-1 levels increased in the ischemic brain tissue due to the infiltration of PECAM-1⁺ leukocytes. Using magnetic resonance imaging, we observed smaller infarct volume, less edema formation, and less brain atrophy in Pecam-1^-/- compared with Pecam-1^+/+ wildtype mice. The transmigration of leukocytes, specifical neutrophils, was selectively reduced by Pecam-1^-/-, as shown by immune fluorescence and flow cytometry in vivo and transmigration assays in vitro. Importantly, inhibition with an anti-PECAM-1 antibody in wildtype mice decreased neutrophil brain influx and infarct.

CONCLUSION

PECAM-1 controls the trans-endothelial migration of neutrophils in a mouse model of ischemic stroke. Antibody blockade of PECAM-1 after stroke onset ameliorates stroke severity in mice, making PECAM-1 an interesting target to dampen post-stroke neuroinflammation, reduce ischemic brain injury, and enhance post-ischemic brain remodeling.

Early Postnatal Comprehensive Biomarkers Cannot Identify Extremely Preterm Infants at Risk of Developing Necrotizing Enterocolitis

Background: Necrotizing enterocolitis (NEC) is a fatal disease where current diagnostic tools are insufficient for preventing NEC. Early predictive biomarkers could be beneficial in identifying infants at high risk of developing NEC. Objective: To explore early biomarkers for predicting NEC in extremely preterm infants (EPIs). Methods: Blood samples were collected on day 2 (median 1.7; range 1.5-2.0) from 40 EPI (median 25 gestational weeks; range 22-27): 11 developed NEC and 29 did not (controls). In each infant, 189 inflammatory, oncological, and vascular proteomic biomarkers were quantified through Proximity Extension Assay. Biomarker expression and clinical data were compared between the NEC group and Controls. Based on biomarker differences, controls were sorted automatically into three subgroups (1, 2, and 3) by a two-dimensional hierarchical clustering analysis. Results: None of the biomarkers differed in expression between all controls and the NEC group. Two biomarkers were higher in Control 1, and 16 biomarkers were lower in Control group 2 compared with the NEC group. No biomarker distinguished Control 3 from the NEC group. Perinatal data were similar in the whole population. Conclusions: Early postnatal comprehensive biomarkers do not identify EPIs at risk of developing NEC in our study. Future studies of predictors of NEC should include sequential analysis of comprehensive proteomic markers in large cohorts.

Evaluation of optimal biopsy location for assessment of histological activity, transcriptomic and immunohistochemical analyses in patients with active Crohn's disease

BACKGROUND

The appropriate location for biopsy procurement relative to an ulcer in active Crohn's disease is unknown.

AIM

To explore the relationship between biopsy location, histological disease activity, proinflammatory gene expression and the presence of inflammatory cells.

METHODS

Fifty-one patients with Crohn's disease and ulcers >0.5 cm diameter in the colon and/or ileum were prospectively enrolled at three centres. Biopsies were obtained from 0 mm, 7 to 8 mm and 21 to 24 mm from the edge of the largest ulcer. Histological activity was blindly assessed with the Global Histological Disease Activity Score, the Robarts Histopathology and Nancy Histological indices. Messenger ribonucleic acid (mRNA) levels for interleukins-6, -8 and -23 (p19 and p40 subunits), CD31 and S100A9 were measured using quantitative polymerase chain reaction. The number of CD3+, CD68+ and myeloperoxidase-positive cells was quantified by immunohistochemistry. Data were analysed using mixed models with location and segment as fixed effects and patients as random effect to account for correlation among segments within a patient.

RESULTS

Histological disease activity scores (P < 0.0001), proinflammatory gene expression levels (P < 0.005) and numbers of myeloperoxidase-positive cells (P < 0.0001) were highest in biopsies from the ulcer edge in the colon and ileum, with decreasing gradients observed with distance from the edge (P < 0.05). No differences between colonic and ileal samples were detected for the parameters measured at any location.

CONCLUSIONS

Biopsies from the ulcer edge in patients with Crohn's disease yielded the greatest histological disease activity and mRNA levels and had similar readouts in the colon and ileum. Research is needed to confirm this conclusion for other measures.

Sterilization Procedure for Temperature-Sensitive Hydrogels Loaded with Silver Nanoparticles for Clinical Applications

Hydrogels (HG) have recognized benefits as drug delivery platforms for biomedical applications. Their high sensitivity to sterilization processes is however one of the greatest challenges regarding their clinical translation. Concerning infection diseases, prevention of post-operatory related infections is crucial to ensure appropriate patient recovery and good clinical outcomes. Silver nanoparticles (AgNPs) have shown good antimicrobial properties but sustained release at the right place is required. Thus, we produced and characterized thermo-sensitive HG based on Pluronic^® F127 loaded with AgNPs (HG-AgNPs) and their integrity and functionality after sterilization by dry-heat and autoclave methods were carefully assessed. The quality attributes of HG-AgNPs were seriously affected by dry-heat methods but not by autoclaving methods, which allowed to ensure the required sterility. Also, direct sterilization of the final HG-AgNPs product proved more effective than of the raw material, allowing simpler production procedures in non-sterile conditions. The mechanical properties were assessed in post mortem rat models and the HG-AgNPs were tested for its antimicrobial properties in vitro using extremely drug-resistant (XDR) clinical strains. The produced HG-AgNPs prove to be versatile, easy produced and cost-effective products, with activity against XDR strains and an adequate gelation time and spreadability features and optimal for in situ biomedical applications.

NOD2- and disease-specific gene expression profiles of peripheral blood mononuclear cells from Crohn’s disease patients

AIM

To investigate disease-specific gene expression profiles of peripheral blood mononuclear cells (PBMCs) from Crohn’s disease (CD) patients in clinical remission.

METHODS

Patients with CD in clinical remission or with very low disease activity according to the Crohn’s disease activity index were genotyped regarding nucleotide-binding oligomerization domain 2 (NOD2), and PBMCs from wild-type (WT)-NOD2 patients, patients with homozygous or heterozygous NOD2 mutations and healthy donors were isolated for further analysis. The cells were cultured with vitamin D, peptidoglycan (PGN) and lipopolysaccharide (LPS) for defined periods of time before RNA was isolated and subjected to microarray analysis using Clariom S assays and quantitative real-time PCR. NOD2- and disease-specific gene expression profiles were evaluated with repeated measure ANOVA by a general linear model.

RESULTS

Employing microarray assays, a total of 267 genes were identified that were significantly up- or downregulated in PBMCs of WT-NOD2 patients, compared to healthy donors after challenge with vitamin D and/or a combination of LPS and PGN (P < 0.05; threshold: ≥ 2-fold change). For further analysis by real-time PCR, genes with known impact on inflammation and immunity were selected that fulfilled predefined expression criteria. In a larger cohort of patients and controls, a disease-associated expression pattern, with higher transcript levels in vitamin D-treated PBMCs from patients, was observed for three of these genes, CLEC5A (P < 0.030), lysozyme (LYZ; P < 0.047) and TREM1 (P < 0.023). Six genes were found to be expressed in a NOD2-dependent manner (CD101, P < 0.002; CLEC5A, P < 0.020; CXCL5, P < 0.009; IL-24, P < 0.044; ITGB2, P < 0.041; LYZ, P < 0.042). Interestingly, the highest transcript levels were observed in patients with heterozygous NOD2 mutations.

CONCLUSION

Our data identify CLEC5A and LYZ as CD- and NOD2-associated genes of PBMCs and encourage further studies on their pathomechanistic roles.

Increased Cell Adhesion Molecules, PECAM-1, ICAM-3, or VCAM-1, Predict Increased Risk for Flare in Patients With Quiescent Inflammatory Bowel Disease

GOALS AND BACKGROUND

Predicting the risk of flare-ups for patients with inflammatory bowel disease (IBD) is difficult. Alterations in gut endothelial regulation of mucosal immune homeostasis might be early events leading to flares in IBD. Cell adhesion molecules (CAMs), in particular, are important in maintaining endothelial integrity and regulating the migration of leukocytes into the gut.

STUDY

We evaluated the mRNA expression of various tight junction proteins, with an emphasis on CAMs, in 40 patients with IBD in clinical remission. Patients were retrospectively assessed at 6, 12, and 24 months after baseline colonoscopy, and at the end of all available follow-up (maximum 65 mo), for flare events to determine whether baseline mRNA expression was associated with subsequent flares.

RESULTS

At all follow-up points, the baseline expression of platelet endothelial cell adhesion molecule-1 (PECAM-1), ICAM-3, and VCAM-1 was significantly higher in patients who flared than in those who did not (2.4-fold elevation, P=0.012 for PECAM-1; 1.9-fold increased, P=0.03 for ICAM-3; and 1.4-fold increased, P=0.02 for VCAM-1). PECAM-1 and ICAM-3 expression was significantly increased in patients who flared as early as 6 months after baseline colonoscopy. In contrast, there were no significant differences between patients with and without flares in baseline expression of other CAMs (ESAM, ICAM-1, ICAM-2, E-selectin, P-selectin, and MadCAM1).

CONCLUSIONS

Increased expression of PECAM-1, ICAM-3, and VCAM-1 in colonic biopsies from patients with IBD in clinical remission is associated with subsequent flares. This suggests that increases in the expression of these proteins may be early events that lead to flares in patients with IBD.

The extracellular matrix in IBD: a dynamic mediator of inflammation

PURPOSE OF REVIEW

The extracellular matrix (ECM) is a frequently overlooked component of the pathogenesis of inflammatory bowel disease (IBD). However, the functional and clinically significant interactions between immune as well as nonimmune cells with the ECM have important implications for disease pathogenesis. In this review, we discuss how the ECM participates in process associated with IBD that involves diverse cell types of the intestine.

RECENT FINDINGS

Remodeling of the ECM is a consistent feature of IBD, and studies have implicated key ECM molecules in IBD pathogenesis. While the majority of prior studies have focused on ECM degradation by proteases, more recent studies have uncovered additional degrading enzymes, identified fragments of ECM components as potential biomarkers, and revealed that ECM synthesis is increased in IBD. These new studies support the notion that the ECM, rather than acting as a passive element, is an active participant in promoting inflammation.

SUMMARY

New studies have offered exciting clues about the function of the ECM during IBD pathogenesis. The balance of ECM synthesis and turnover is altered in IBD, and the molecules involved exhibit discreet biological functions that regulate inflammation on the basis of specific cell type and matrix molecule.

Moderate Hypoxia Exhibits Increased Endothelial Progenitor Vessel-forming Ability However Gestational Diabetes Caused to Impede Compensatory Defense Reaction

Endothelium represents a defense barrier and responds and integrates neuro humoral stimulus which describes as a compensatory mechanism. Endothelium formed with endothelial cells (ECs) and their progenitors. Endothelial progenitor cells (EPCs) represent minor subpopulation of mononuclear cells in the blood. During acute hypoxia, larger amount of EPCs mobilize into the peripheral blood and they directly contribute revascularization process. One of the subtypes of EPC is termed endothelial colony forming cells (ECFCs) which they possess de novo vessel-forming ability. The present study aims to investigate the role of hypoxia in EPCs functional and vessel-forming ability. Furthermore, it was investigated whether fetal exposure to a diabetic intrauterine environment influence EPCs adaptation ability. Human umbilical cord blood (HUCB) derived ECFCs were selected in all experimental procedures obtained from normal and gestational diabetes mellitus (GDM) subjects via in vitro cell culture methods. Early passage (<5) HUCB ECFCs obtain from GDM (n; 5) and control (n; 5) subjects were cultured with plates pre-coated with collagen in vitro 72 h hypoxic as well as normoxic condition. Endothelial, angiogenic and hypoxia associated gene specific primers designed to perform Real-time PCR. Senescenes assay conducted onto HUCB ECFCs to investigate their functional clonogenic ability. To quantify their vessel forming ability matrigel assay was applied. These data demonstrates that moderate hypoxia results increased vessel-forming ability and VEGFA expression in HUCB ECFCs obtained from control subjects. However, GDM caused to impede compensatory defense reaction against hypoxia which observed in control subjects. Thus, it illuminates beneficial information related future therapeutic modalities.

The Gastrointestinal Circulation: Physiology and Pathophysiology

The gastrointestinal (GI) circulation receives a large fraction of cardiac output and this increases following ingestion of a meal. While blood flow regulation is not the intense phenomenon noted in other vascular beds, the combined responses of blood flow, and capillary oxygen exchange help ensure a level of tissue oxygenation that is commensurate with organ metabolism and function. This is evidenced in the vascular responses of the stomach to increased acid production and in intestine during periods of enhanced nutrient absorption. Complimenting the metabolic vasoregulation is a strong myogenic response that contributes to basal vascular tone and to the responses elicited by changes in intravascular pressure. The GI circulation also contributes to a mucosal defense mechanism that protects against excessive damage to the epithelial lining following ingestion of toxins and/or noxious agents. Profound reductions in GI blood flow are evidenced in certain physiological (strenuous exercise) and pathological (hemorrhage) conditions, while some disease states (e.g., chronic portal hypertension) are associated with a hyperdynamic circulation. The sacrificial nature of GI blood flow is essential for ensuring adequate perfusion of vital organs during periods of whole body stress. The restoration of blood flow (reperfusion) to GI organs following ischemia elicits an exaggerated tissue injury response that reflects the potential of this organ system to generate reactive oxygen species and to mount an inflammatory response. Human and animal studies of inflammatory bowel disease have also revealed a contribution of the vasculature to the initiation and perpetuation of the tissue inflammation and associated injury response.

Targeting endothelial CD146 attenuates colitis and prevents colitis-associated carcinogenesis

Recently, enhanced CD146 expression was reported on endothelial cells in intestinal biopsies from patients with inflammatory bowel disease. However, the underlying mechanism remains unknown. Here, we found that overexpressed endothelial CD146 promoted the inflammatory responses in inflammatory bowel disease, which further potentiated the occurrence of colitis-associated colorectal carcinogenesis. Eliminating endothelial CD146 by conditional knockout significantly ameliorated the severity of inflammation in two different murine models of colitis, and decreased tumor incidence and tumor progression in a murine model of colitis-associated colorectal carcinogenesis. Mechanistic study showed that cytokine tumor necrosis factor-α (TNF-α) up-regulated the expression of endothelial CD146 through NF-κB transactivation. In turn, the enhanced endothelial CD146 expression promoted both angiogenesis and proinflammatory leukocyte extravasations, contributing to inflammation. Using an anti-CD146 antibody, AA98, alone or together with an anti-TNF-α antibody significantly attenuated colitis and prevented colitis-associated colorectal carcinogenesis in mice. Our study provides the first evidence that CD146 plays a dual role on endothelium, facilitating leukocyte extravasations and angiogenesis, thus promoting inflammation. This finding not only reveals the function and regulating mechanism of CD146 in inflammatory bowel disease, but also provides a promising therapeutic strategy for treating inflammatory bowel disease and preventing colitis-associated colorectal carcinogenesis.

Myometrial immune cells contribute to term parturition, preterm labour and post-partum involution in mice

This study aimed to determine the mechanism of uterine activation during labour, both term (TL) and preterm (PTL). We hypothesized that the peripheral leucocytes are recruited to uterine tissues by locally produced cytokines where they contribute to the initiation of parturition. Mouse uteri were collected (i) during gestation, TL and post-partum (PP), (ii) during PTL initiated by intrauterine infusion of LPS (125 μg) or (iii) injection of the progesterone receptor antagonist RU486 and analysed for multiple cytokine expression levels by real-time polymerase chain reaction (RT-PCR) and 23-plex Cytokine assay or enzymatically dispersed for assessment of immune cell populations. Markers of myeloid cell differentiation (Gr1, Neu7/4 and F4/80) were evaluated by FACS to define tissue macrophages (Macs), monocytes (M) and neutrophils (N) and by immunohistochemistry to detect tissue Macs and N. Our results indicate that: (1) Macs were elevated in mouse myometrium before TL (P < 0.05) followed by an increase in M and N; these changes were accompanied by an increase in multiple pro-inflammatory cytokines/chemokines genes. The expression of corresponding proteins increased PP. (2) TL and RU486-PTL models showed similar gene/protein expression profiles, (3) LPS-PTL was characterized by strong pro-inflammatory response and massive influx of N in myometrial tissues showing a pattern different from TL and RU486-PTL, (4) The PP period appears similar in all three models, with elevated myometrial cytokine levels and high infiltration of immune cells. We concluded that leucocytes infiltrate myometrium around the time of parturition implicating their potential role in labour activation (both term and preterm) and major role in PP uterine involution.

Physiologic uterine inflammation and labor onset: integration of endocrine and mechanical signals

The mechanisms underlying the preparation of the uterus for labor are not fully understood. Our previous studies have shown that during pregnancy, the uterine muscle (myometrium) undergoes dramatic phenotypic modulation culminating in term labor. The current review will discuss the cellular mechanisms involved in the regulation of myometrial activity and its modulation by endocrine signals and by mechanical stimulation of the uterus by the growing fetus. In particular, the contribution of uterine inflammation to the onset of labor will be described. We provide evidence that increased production of cytokines/chemokines in pregnant myometrium is associated with uterine occupancy and regulated by progesterone, suggesting the integration of mechanical and endocrine signals. Myometrial cells can actively participate in the inflammatory process in the uterus through the release of multiple proinflammatory cytokines and chemokines, providing a strong signal for activation of immune cells, their subsequent infiltration into pregnant uterus, and the initiation of labor.

Role of high endothelial postcapillary venules and selected adhesion molecules in periodontal diseases: a review

Periodontitis is accompanied by the proliferation of small blood vessels in the gingival lamina propria. Specialized postcapillary venules, termed periodontal high endothelial-like venules, are also present, and demonstrate morphological and functional traits similar to those of high endothelial venules (HEVs) in lymphatic organs. The suggested role of HEVs in the pathogenesis of chronic periodontitis involves participation in leukocyte transendothelial migration and therefore proinflammatory effects appear. Recent observations suggest that chronic periodontitis is an independent risk factor for systemic vascular disease and may result in stimulation of the synthesis of acute phase protein by cytokines released by periodontal high endothelial cells (HECs). However, tissue expression of HEV-linked adhesion molecules has not been evaluated in the gingiva of patients with chronic periodontitis. This is significant in relation to potential therapy targeting expression of the adhesion molecules. In this review, current knowledge of HEV structure and the related expression of four surface adhesion molecules of HECs [CD34, platelet endothelial cell adhesion molecule 1, endoglin and intercellular adhesion molecule 1 (ICAM-1)], involved in the key steps of the adhesion cascade in periodontal diseases, are discussed. Most studies on the expression of adhesion molecules in the development and progression of periodontal diseases pertain to ICAM-1 (CD54). Studies by the authors demonstrated quantitatively similar expression of three of four selected surface markers in gingival HEVs of patients with chronic periodontitis and in HEVs of reactive lymph nodes, confirming morphological and functional similarity of HEVs in pathologically altered tissues with those in lymphoid tissues.

Mucosal gene expression of cell adhesion molecules, chemokines, and chemokine receptors in patients with inflammatory bowel disease before and after infliximab treatment

OBJECTIVES

Inflammatory bowel disease (IBD) is characterized by a continuous influx of leukocytes into the gut wall. This migration is regulated by cell adhesion molecules (CAMs), and selective antimigration therapies have been developed. This study investigated the effect of infliximab therapy on the mucosal gene expression of CAMs in IBD.

METHODS

Mucosal gene expression of 69 leukocyte/endothelial CAMs and E-cadherin was investigated in 61 IBD patients before and after first infliximab infusion and in 12 normal controls, using Affymetrix gene expression microarrays. Quantitative reverse transcriptase-PCR (qRT-PCR), immunohistochemistry, and western blotting were used to confirm the microarray data.

RESULTS

When compared with control colons, the colonic mucosal gene expression of most leukocyte/endothelial adhesion molecules was upregulated and E-cadherin gene expression was downregulated in active colonic IBD (IBDc) before therapy, with no significant colonic gene expression differences between ulcerative colitis and colonic Crohn's disease. Infliximab therapy restored the upregulations of leukocyte CAMs in IBDc responders to infliximab that paralleled the disappearance of the inflammatory cells from the colonic lamina propria. Also, the colonic gene expression of endothelial CAMs and of most chemokines/chemokine receptors returned to normal after therapy in IBDc responders, and only CCL20 and CXCL1-2 expression remained increased after therapy in IBDc responders vs. control colons. When compared with control ileums, the ileal gene expression of MADCAM1, THY1, PECAM1, CCL28, CXCL1, -2, -5, -6, and -11, and IL8 was increased and CD58 expression was decreased in active ileal Crohn's disease (CDi) before therapy, and none of the genes remained dysregulated after therapy in CDi responders vs. control ileums. This microarray study identified a number of interesting targets for antiadhesion therapy including PECAM1, IL8, and CCL20, besides the currently studied α4β7 integrin-MADCAM1 axis.

CONCLUSIONS

Our data demonstrate that many leukocyte/endothelial CAMs and chemokines/chemokine receptors are upregulated in inflamed IBD mucosa. Controlling the inflammation with infliximab restores most of these dysregulations in IBD. These results show that at least part of the mechanism of anti-tumor necrosis factor-α therapy goes through downregulation of certain adhesion molecules.

Role of the endothelium in inflammatory bowel diseases

Inflammatory bowel diseases (IBD) are a complex group of diseases involving alterations in mucosal immunity and gastrointestinal physiology during both initiation and progressive phases of the disease. At the core of these alterations are endothelial cells, whose continual adjustments in structure and function coordinate vascular supply, immune cell emigration, and regulation of the tissue environment. Expansion of the endothelium in IBD (angiogenesis), mediated by inflammatory growth factors, cytokines and chemokines, is a hallmark of active gut disease and is closely related to disease severity. The endothelium in newly formed or inflamed vessels differs from that in normal vessels in the production of and response to inflammatory cytokines, growth factors, and adhesion molecules, altering coagulant capacity, barrier function and blood cell recruitment in injury. This review examines the roles of the endothelium in the initiation and propagation of IBD pathology and distinctive features of the intestinal endothelium contributing to these conditions.

Regional mucosa-associated microbiota determine physiological expression of TLR2 and TLR4 in murine colon

Many colonic mucosal genes that are highly regulated by microbial signals are differentially expressed along the rostral-caudal axis. This would suggest that differences in regional microbiota exist, particularly mucosa-associated microbes that are less likely to be transient. We therefore explored this possibility by examining the bacterial populations associated with the normal proximal and distal colonic mucosa in context of host Toll-like receptors (TLR) expression in C57BL/6J mice housed in specific pathogen-free (SPF) and germ-free (GF) environments. 16S rRNA gene-based terminal restriction fragment length polymorphism (T-RFLP) and clone library analysis revealed significant differences in the community structure and diversity of the mucosa-associated microbiota located in the distal colon compared to proximal colon and stool, the latter two clustering closely. Differential expression of colonic TLR2 and TLR4 along the proximal-distal axis was also found in SPF mice, but not in GF mice, suggesting that enteric microbes are essential in maintaining the regional expression of these TLRs. TLR2 is more highly expressed in proximal colon and decreases in a gradient to distal while TLR4 expression is highest in distal colon and a gradient of decreased expression to proximal colon is observed. After transfaunation in GF mice, both regional colonization of mucosa-associated microbes and expression of TLRs in the mouse colon were reestablished. In addition, exposure of the distal colon to cecal (proximal) microbiota induced TLR2 expression. These results demonstrate that regional colonic mucosa-associated microbiota determine the region-specific expression of TLR2 and TLR4. Conversely, region-specific host assembly rules are essential in determining the structure and function of mucosa-associated microbial populations. We believe this type of host-microbial mutualism is pivotal to the maintenance of intestinal and immune homeostasis.

Periovulatory leukocyte infiltration in the rat ovary

Ovulation is preceded by intraovarian inflammatory reactions that occur in response to the preovulatory gonadotropin surge. As a main inflammatory event, leukocytes infiltrate the ovary and release proteolytic enzymes that degrade the extracellular matrix weakening the follicular wall, a required step for follicle rupture. This study aimed to quantitatively measure the infiltrating leukocytes, determine their cell types, and localize infiltration sites in the periovulatory rat ovary. Cycling adult and gonadotropin-stimulated immature rats were used as animal models. Ovaries were collected at five different stages of estrous cycle in the adult rats (diestrus, 1700 h; proestrus, 1500 h; proestrus, 2400 h; estrus, 0600 h; and metestrus, 1700 h) and at five different time points after superovulation induction in the immature rats (pregnant mare's serum gonadotrophin, 0 h; pregnant mare's serum gonadotrophin, 48 h; human chorionic gonadotropin, 6 h; human chorionic gonadotropin, 12 h; and human chorionic gonadotropin, 24 h). The ovaries were either dissociated into a single cell suspension for flow cytometric analysis or fixed for immunohistochemical localization of the leukocytes. Similar numbers of leukocytes were seen throughout the estrous cycle (approximately 500,000/ovary), except proestrus 2400 when 2-fold higher numbers of leukocytes were found (approximately 1.1 million/ovary). A similar trend of periovulatory rise of leukocyte numbers was seen in the superovulation-induced immature rat model, recapitulating a dramatic increase in leukocyte numbers upon gonadotropin stimulation. Both macrophage/granulocytes and lymphocytes were among the infiltrating leukocytes and were localized in the theca and interstitial tissues, where platelet-endothelial cell adhesion molecule-1 and intercellular adhesion molecule-1 may play roles in the transmigration of leukocytes, because their expressions correlates spatiotemporally with the infiltrating leukocytes. In addition, a strong inverse relationship between leukocyte numbers in the ovary and spleen, as well as significant reduction of leukocyte infiltration in the splenectomized rats, were seen, indicating that the spleen may serve as an immediate supplier of leukocytes to the periovulatory ovary.

PECAM-1: conflicts of interest in inflammation

Platelet endothelial cell adhesion molecule-1 (PECAM-1, CD31) is a cell adhesion and signaling receptor that is expressed on hematopoietic and endothelial cells. PECAM-1 is vital to the regulation of inflammatory responses, as it has been shown to serve a variety of pro-inflammatory and anti-inflammatory functions. Pro-inflammatory functions of PECAM-1 include the facilitation of leukocyte transendothelial migration and the transduction of mechanical signals in endothelial cells emanating from fluid shear stress. Anti-inflammatory functions include the dampening of leukocyte activation, suppression of pro-inflammatory cytokine production, and the maintenance of vascular barrier integrity. Although PECAM-1 has been well-characterized and studied, the mechanisms through which PECAM-1 regulates these seemingly opposing functions, and how they influence each other, are still not completely understood. The purpose of this review, therefore, is to provide an overview of the pro- and anti-inflammatory functions of PECAM-1 with special attention paid to mechanistic insights that have thus far been revealed in the literature in hopes of gaining a clearer picture of how these opposing functions might be integrated in a temporal and spatial manner on the whole organism level. A better understanding of how inflammatory responses are regulated should enable the development of new therapeutics that can be used in the treatment of acute and chronic inflammatory disorders.

VE-cadherin and PECAM-1 enhance ALL migration across brain microvascular endothelial cell monolayers

OBJECTIVE

Infiltration of the central nervous system (CNS) by leukemia is a problematic disease manifestation of acute lymphoblastic leukemia (ALL). The mechanisms by which leukocytes interact with human brain-derived microvasculature endothelial cells (HBMEC) and enter the CNS are largely derived from models of inflammation. However, our data indicate that ALL cells do not elicit an inflammatory phenotype by HBMEC. Our current investigation focuses on the contribution of the unique coexpression of vascular endothelial (VE)-cadherin and platelet endothelial cell adhesion molecule-1 (PECAM-1) by ALL in mediating leukemic cell interactions with HBMEC as an in vitro model of the blood-brain barrier.

MATERIALS AND METHODS

Primary ALL and ALL cell lines were evaluated for VE-cadherin and PECAM-1 expression. Lentiviral-mediated transduction of VE-cadherin and PECAM-1 into REH cells and antibody neutralization of VE-cadherin and PECAM-1 in SUP-B15 cells was used to delineate the role of these two proteins in mediating ALL adhesion to, and migration through, HBMEC monolayers.

RESULTS

Although cell line models indicate that VE-cadherin and PECAM-1 expression is found on the surface Philadelphia chromosome-positive ALL, evaluation of primary ALL demonstrates that VE-cadherin and PECAM-1 are expressed independent of Philadelphia status. Expression of VE-cadherin and PECAM-1 by ALL enhanced the adhesion of ALL to HBMEC, while expression of PECAM-1 enhanced ALL adhesion to, and migration through, HBMEC.

CONCLUSIONS

Expression of VE-cadherin and PECAM-1 by ALL cells positions them to interact with HBMEC. By increasing our understanding of molecular mechanisms through which ALL cells gain entry into the CNS, new strategies may be designed to prevent leukemia cell entry into the CNS.

Blood flow patterns spatially associated with platelet aggregates in murine colitis

In the normal murine mucosal plexus, blood flow is generally smooth and continuous. In inflammatory conditions, such as chemically-induced murine colitis, the mucosal plexus demonstrates markedly abnormal flow patterns. The inflamed mucosal plexus is associated with widely variable blood flow velocity as well as discontinuous and even bidirectional flow. To investigate the mechanisms responsible for these blood flow patterns, we used intravital microscopic examination of blood flow within the murine mucosal plexus during dextran sodium sulphate-and trinitrobenzenesulfonic acid-induced colitis. The blood flow patterns within the mucosal plexus demonstrated flow exclusion in 18% of the vessel segments (P < 0.01). Associated with these segmental exclusions was significant variation in neighboring flow velocities. Intravascular injection of fluorescent platelets demonstrated platelet incorporation into both fixed and rolling platelet aggregates. Rolling platelet aggregates (mean velocity 113 microm/sec; range, 14-186 microm/sec) were associated with reversible occlusions and flow variations within the mucosal plexus. Gene expression profiles of microdissected mucosal plexus demonstrated enhanced expression of genes for CCL3, CXCL1, CCL2, CXCL5, CCL7, CCL8, and Il-1b (P < 0.01), and decreased expression of CCL6 (P < 0.01). These results suggest that platelet aggregation, activated by the inflammatory mileau, contributes to the complex flow dynamics observed in acute murine colitis.

Blocking platelet/endothelial cell adhesion molecule 1 (PECAM) inhibits disease progression and prevents joint erosion in established collagen antibody-induced arthritis

Collagen antibody-induced arthritis is a robust murine model of arthritis that histologically recapitulates the inflammatory characteristics of rheumatoid arthritis including pannus formation and destruction of articular cartilage and bone. PECAM is a molecule expressed by both leukocytes and endothelial cells that has been shown to play a major role in the extravasation of leukocytes into sites of inflammation. Genetic deletion of many molecules will blunt the onset and progression of arthritis in murine models, as will administration of various anti-inflammatory therapies given prior to the onset of disease. However, patients seek medical attention when symptomatic, which means that the disease is well established. We investigated whether blocking PECAM interactions would inhibit progression of established disease in the collagen antibody-induced arthritis model. We report that treatment of symptomatic mice with a PECAM-Fc chimera significantly reduced inflammation and virtually eliminated cartilage and bone destruction. The results suggest that therapies that block PECAM function may be beneficial in the treatment of established arthritis.

Advances in studies on relation between inflammatory bowel disease and immunity

Inflammatory bowel disease is a chronic inflammatory disease of the gastrointestinal tract. Its main clinical manifestations are abdominal pain and diarrhea. Its etiology is complicated. Immune system is very important. Following factors, such as intestinal environment, immune cells, human leukocyte antigens, antibodies, anti- laminaribioside antibody, anti-chitobioside antibody IgA, cytokines, cell adhesion molecules, NO and NF-κB, play a key role in the pathogenesis of inflammatory bowel disease. Inflammatory bowel disease is related to all these factors. This paper reviews the possible role of these immune factors in the pathogenesis of inflammatory bowel disease.