How do lymphocytes know where to go: current concepts and enigmas of lymphocyte homing

Acute stress transiently activates macrophages and chemokines in cervical lymph nodes

Acute restraint stress (RS) is routinely used to study the effects of psychological and/or physiological stress. We evaluated the impact of RS on cervical lymph nodes in rats at molecular and cellular levels. Male Sprague-Dawley rats were subjected to stress by immobilization for 30, 60, and 120 min (RS30, RS60, and RS120, respectively) and compared with rats of a no-stress control (C) group. The expression of genes encoding chemokines CXCL1/CXCL2 (Cxcl1 and Cxcl2) and their receptor CXCR2 (Cxcr2) was analyzed using reverse transcription-quantitative PCR (RT-qPCR) and microarray analyses. Immunohistochemistry and in situ hybridization were performed to determine the expression of these proteins and the macrophage biomarker CD68. Microarray analysis revealed that the expression of 514 and 496 genes was upregulated and downregulated, respectively, in the RS30 group. Compared with the C group, the RS30 group exhibited a 23.0-, 13.0-, and 1.6-fold increase in Cxcl1, Cxcl2, and Cxcr2 expression. Gene Ontology analysis revealed the involvement of these three upregulated genes in the cytokine network, inflammation, and leukocyte chemotaxis and migration. RT-qPCR analysis indicated that the mRNA levels of Cxcl1 and Cxcl2 were significantly increased in the RS30 group but were reverted to normal levels in the RS60 and RS120 groups. Cxcr2 mRNA level was significantly increased in the RS30 and RS120 groups compared with that in the C group. RS-induced CXCL1-immunopositive cells corresponded to B/plasma cells, whereas CXCL2-immunopositive cells corresponded to endothelial cells of the high endothelial venules. Stress-induced CXCR2-immunopositive cells corresponded to macrophages. Psychological and/or physiological stress induces an acute stress response and formation of an immunoreactive microenvironment in cervical lymph nodes, with the CXCL1/CXCL2-CXCR2 axis being pivotal in the acute stress response.

Human Breast Milk: From Food to Active Immune Response With Disease Protection in Infants and Mothers

Breastfeeding is associated with long-term wellbeing including low risks of infectious diseases and non-communicable diseases such as asthma, cancer, autoimmune diseases and obesity during childhood. In recent years, important advances have been made in understanding the human breast milk (HBM) composition. Breast milk components such as, non-immune and immune cells and bioactive molecules, namely, cytokines/chemokines, lipids, hormones, and enzymes reportedly play many roles in breastfed newborns and in mothers, by diseases protection and shaping the immune system of the newborn. Bioactive components in HBM are also involved in tolerance and appropriate inflammatory response of breastfed infants if necessary. This review summarizes the current literature on the relationship between mother and her infant through breast milk with regard to disease protection. We will shed some light on the mechanisms underlying the roles of breast milk components in the maintenance of health of both child and mother.

Gene network expression of whole blood leukocytes in dairy cows with different milk yield at dry-off

Dairy cows at dry-off undergo several management and physiological changes, resulting in alterations in plasma biomarkers of inflammation, oxidative stress, and immune system. High milk yield at the end of lactation exacerbates these responses. The underlying mechanism of these changes has yet to be elucidated. We hypothesized altered leukocyte gene expression after dry-off and different responses in cows with different milk yield. Thirteen Holstein dairy cows were sampled at the turn of dry-off to investigated whole blood leukocyte gene expression and were grouped according to the average milk yield during the last week of lactation: low (< 15 kg/d) and high milk yield (> 15 kg/d). Blood samples were collected in PAXgene tubes (Preanalytix, Hombrechtikon, Switzerland) at -7, 7, and 34 days from dry-off (DFD) to measure mRNA abundance of 37 genes. Normalized gene abundance data were subjected to MIXED model ANOVA (SAS Institute Inc., Cary, NC). Compared with -7 DFD, at 7 DFD RNA abundance of lipoxygenase genes (ALOX5, ALOX15) and myeloperoxidase (MPO) increased, and that of the antioxidant gene (SOD2) decreased. Meanwhile, genes related to recognition and immune mediation (CD16, MYD88, TLR2), migration and cell adhesion (CX3CR1, ITGAL, ITGB2, TLN1), and the antimicrobial gene MMP9 were downregulated at 7 or 34 DFD, whereas the antimicrobial IDO1 gene was upregulated. Compared with low-producing cows, cows with high milk yield at dry-off cows had upregulated expression of the pro-inflammatory cytokines IL8 and IL18 and a greater reduction in transcript abundance of the toll-like receptor (TLR) recognition-related gene TLR2. Overall, the dry-off confirmed to be a phase of intense changes, triggering an inflammatory response and somewhat suppressing leukocyte immune function. In cows with high milk yield during the week before dry-off, the inflammatory response was exacerbated.

SSAO/VAP-1 in Cerebrovascular Disorders: A Potential Therapeutic Target for Stroke and Alzheimer's Disease

The semicarbazide-sensitive amine oxidase (SSAO), also known as vascular adhesion protein-1 (VAP-1) or primary amine oxidase (PrAO), is a deaminating enzyme highly expressed in vessels that generates harmful products as a result of its enzymatic activity. As a multifunctional enzyme, it is also involved in inflammation through its ability to bind and promote the transmigration of circulating leukocytes into inflamed tissues. Inflammation is present in different systemic and cerebral diseases, including stroke and Alzheimer’s disease (AD). These pathologies show important affectations on cerebral vessels, together with increased SSAO levels. This review summarizes the main roles of SSAO/VAP-1 in human physiology and pathophysiology and discusses the mechanisms by which it can affect the onset and progression of both stroke and AD. As there is an evident interrelationship between stroke and AD, basically through the vascular system dysfunction, the possibility that SSAO/VAP-1 could be involved in the transition between these two pathologies is suggested. Hence, its inhibition is proposed to be an interesting therapeutical approach to the brain damage induced in these both cerebral pathologies.

The expression of chemerin and its receptors (CMKLR1, GPR1, CCRL2) in the porcine uterus during the oestrous cycle and early pregnancy and in trophoblasts and conceptuses

Recent research has demonstrated that chemerin may take part in the regulation of reproduction. The aim of this study was to determine the expression of chemerin system - chemerin and its receptors, chemokine-like receptor 1 (CMKLR1), G protein-coupled receptor 1 (GPR1) and C-C chemokine receptor-like 2 (CCRL2) - in the porcine uterus during the oestrous cycle and early pregnancy, and in trophoblasts and conceptuses by real-time PCR and western blotting. Chemerin concentrations in uterine luminal flushings (ULF) were determined using ELISA test. In the endometrium, the highest expression of chemerin and GPR1 proteins was observed during the mid-luteal phase; CMKLR1, during the late luteal phase; and CCRL2, during the follicular phase of the cycle. In the myometrium, chemerin protein expression was enhanced during the early luteal phase, and chemerin receptor proteins were highly expressed during the follicular phase. In the endometrium of pregnant pigs, the highest expression of chemerin and CCRL2 protein was observed during implantation; CMKLR1, during placentation; and GPR1, during embryo migration. In the myometrium, chemerin and CCRL2 protein expression increased at the end of implantation, and the expression of CMKLR1 and GPR1 protein was enhanced during implantation. In the conceptuses and trophoblasts, the highest expression of chemerin system proteins was observed during placentation, with the exception of GPR1 protein in the trophoblasts. The highest concentrations of the analysed adipokine were observed in ULF during the luteal phase of the cycle and during maternal recognition of pregnancy. This is the first study to demonstrate that the expression of the chemerin system in the porcine uterus, conceptuses and trophoblasts, and chemerin concentrations in ULF are influenced by the hormonal milieu in different stages of the oestrous cycle and in early pregnancy. The present results also suggest that chemerin is implicated in the regulation of reproductive functions in pigs.

Pegbovigrastim Treatment around Parturition Enhances Postpartum Immune Response Gene Network Expression of whole Blood Leukocytes in Holstein and Simmental Cows

Simple Summary

The innate and adaptive immune system of dairy cows is impaired during the transition period, leading to an increase in susceptibility to infectious disease. Pegbovigrastim is a recombinant form of a granulocyte colony-stimulating factor that stimulates differentiation of hemopoietic stem cells to granulocytes and shortens maturation time within the bone marrow and release in circulation. The objective of the present study was to explore the effect of pegbovigrastim on whole blood leukocytes by analyzing the expression of 34 genes involved in immune and inflammatory responses immediately after calving in Simmental, a dual-purpose cow breed selected for both meat and milk production, and Holstein, a cow breed highly specialized for milk production. This study provides insight into immune cell functions impacted by pegbovigrastim treatment. Treatment of cows with pegbovigrastim increased the mRNA abundance level of most genes investigated, suggesting a thorough activation of the immune machinery during the critical post-partum period.

Abstract

Pegbovigrastim is a commercial long-acting analog of bovine granulocyte colony-stimulating factor (rbG-CSF) that promotes the increased count and functionality of polymorphonuclear cells in dairy cows around the time of parturition. We hypothesized that pegbovigrastim administered to periparturient cows at approximately seven days before parturition and within 24 hours after calving could affect the profiles of gene networks involved in leukocyte function. Blood was collected on Day 3 after calving from treated groups (pegbovigrastim (PEG); 13 Simmental (seven multiparous and six primiparous) and 13 Holstein (seven multiparous and six primiparous) cows) that received pegbovigrastim (Imrestor; Elanco Animal Health) and controls (CTR; 13 Simmental (seven multiparous and six primiparous) and 13 Holstein (six multiparous and seven primiparous) cows) that received saline solution. Blood from all cows was sampled from the jugular vein in a PAXgene Blood RNA System tube (Preanalytix, Hombrechtikon, Switzerland) for RNA extraction. The RT-qPCR analysis was performed to investigate a panel of 34 genes of interest, representing recognition, immune mediation, migration, cell adhesion, antimicrobial strategies, inflammatory cascade, oxidative pattern, and leukotrienes in whole blood leukocytes. Normalized data were subjected to the MIXED model of SAS (ver. 9.4) with treatment, breed, parity, and their interaction as fixed effects. Compared with CTR, whole blood leukocytes of PEG cows had higher expression of genes involved in recognition and immune modulation (CD14, CD16, MYD88, TLR2, and TLR4), cell adhesion (ITGB2, ITGAL, TLN1, SELL, SELPLG, and CD44), antimicrobial activity (MMP9, LTF, and LCN2), and inflammatory cascade (CASP1, TNFRSF1A, IL1B, IL1R, IL18, IRAK1, NLRP3, and S100A8). This suggested an improvement of migration, adhesion, and antimicrobial ability and an enhanced inflammatory response, which in turn could trigger immune cell activation and enhance function. Expression of SOD2 and ALOX5 was also greater in the PEG group. In contrast, compared with CTR cows, PEG led to lower expression of RPL13A, ALOX15, IL8, and TNF. Overall, leukocytes from Simmental compared with Holstein cows had greater expression of IDO1, RPL13A, ALOX5, CD44, CX3CR1, ITGB2, and TNFA, whereas expression of CD16 and TLR2 was lower. Overall, compared with multiparous cows, primiparous cows had higher expression of IL1B, IL18, MYD88, SELL, and TLR2 and lower expression of MMP9. Simmental cows seemed more sensitive to induction of the immune system after calving, as revealed by the greater abundance of genes involved in immune system adaptation, regardless of pegbovigrastim treatment. Primiparous cows undergoing a new stress condition with respect to older cows were characterized by leukocytes with a higher inflammatory response. In conclusion, pegbovigrastim led to higher expression levels of most genes involved in the processes investigated, suggesting a thorough activation of the immune machinery during the critical post-partum period.

Robo4 contributes to the turnover of Peyer's patch B cells

All leukocytes can get entrance into the draining lymph nodes via the afferent lymphatics but only lymphoid cells can leave the nodes. The molecular mechanisms behind this phenomenon have remained unknown. We employed genome wide microarray analyses of the subcapsular sinus and lymphatic sinus (LS) endothelial cells and found Robo4 to be selectively expressed on LS lymphatics. Further analyses showed high Robo4 expression in lymphatic vessels of Peyer's patches, which only have efferent lymphatic vessels. In functional assays, Robo4-deficient animals showed accumulation of naïve  B cells (CD19⁺/CD62L^hi/CD44^lo) in Peyer's patches, whereas no difference was seen within other lymphocyte subtypes. Short-term lymphocyte homing via high endothelial venules to peripheral and mesenteric lymph nodes and Peyer's patches was also slightly impaired in Robo4 knockout animals. These results show for the first time, selective expression of Robo4 in the efferent arm of the lymphatics and its role in controlling the turnover of a subset of B lymphocytes from Peyer's patches.

Comparative pathophysiology and management of protein-losing enteropathy

Protein‐losing enteropathy, or PLE, is not a disease but a syndrome that develops in numerous disease states of differing etiologies and often involving the lymphatic system, such as lymphangiectasia and lymphangitis in dogs. The pathophysiology of lymphatic disease is incompletely understood, and the disease is challenging to manage. Understanding of PLE mechanisms requires knowledge of lymphatic system structure and function, which are reviewed here. The mechanisms of enteric protein loss in PLE are identical in dogs and people, irrespective of the underlying cause. In people, PLE is usually associated with primary intestinal lymphangiectasia, suspected to arise from genetic susceptibility, or “idiopathic” lymphatic vascular obstruction. In dogs, PLE is most often a feature of inflammatory bowel disease (IBD), and less frequently intestinal lymphangiectasia, although it is not proven which process is the true driving defect. In cats, PLE is relatively rare. Review of the veterinary literature (1977‐2018) reveals that PLE was life‐ending in 54.2% of dogs compared to published disease‐associated deaths in IBD of <20%, implying that PLE is not merely a continuum of IBD spectrum pathophysiology. In people, diet is the cornerstone of management, whereas dogs are often treated with immunosuppression for causes of PLE including lymphangiectasia, lymphangitis, and crypt disease. Currently, however, there is no scientific, extrapolated, or evidence‐based support for an autoimmune or immune‐mediated mechanism. Moreover, people with PLE have disease‐associated loss of immune function, including lymphopenia, severe CD4+ T‐cell depletion, and negative vaccinal titers. Comparison of PLE in people and dogs is undertaken here, and theories in treatment of PLE are presented.

PECAM-1 isoforms, eNOS and endoglin axis in regulation of angiogenesis

Vascular development and maintenance of proper vascular function through various regulatory mechanisms are critical to our wellbeing. Delineation of the regulatory processes involved in development of the vascular system and its function is one of the most important topics in human physiology and pathophysiology. Platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31), a cell adhesion molecule with proangiogenic and proinflammatory activity, has been the subject of numerous studies. In the present review, we look at the important roles that PECAM-1 and its isoforms play during angiogenesis, and its molecular mechanisms of action in the endothelium. In the endothelium, PECAM-1 not only plays a role as an adhesion molecule but also participates in intracellular signalling pathways which have an impact on various cell adhesive mechanisms and endothelial nitric oxide synthase (eNOS) expression and activity. In addition, recent studies from our laboratory have revealed an important relationship between PECAM-1 and endoglin expression. Endoglin is an essential molecule during angiogenesis, vascular development and integrity, and its expression and activity are compromised in the absence of PECAM-1. In the present review we discuss the roles that PECAM-1 isoforms may play in modulation of endothelial cell adhesive mechanisms, eNOS and endoglin expression and activity, and angiogenesis.

Long-term antibody memory induced by synthetic peptide vaccination is protective against Streptococcus pyogenes infection and is independent of memory T cell help

Streptococcus pyogenes (group A Streptococcus [GAS]) is a leading human pathogen associated with a diverse array of mucosal and systemic infections. Vaccination with J8, a conserved region synthetic peptide derived from the M-protein of GAS and containing only 12 aa from GAS, when conjugated to diphtheria toxoid, has been shown to protect mice against a lethal GAS challenge. Protection has been previously shown to be Ab-mediated. J8 does not contain a dominant GAS-specific T cell epitope. The current study examined long-term Ab memory and dissected the role of B and T cells. Our results demonstrated that vaccination generates specific memory B cells (MBC) and long-lasting Ab responses. The MBC response can be activated following boost with Ag or limiting numbers of whole bacteria. We further show that these memory responses protect against systemic infection with GAS. T cell help is required for activation of MBC but can be provided by naive T cells responding directly to GAS at the time of infection. Thus, individuals whose T cells do not recognize the short synthetic peptide in the vaccine will be able to generate a protective and rapid memory Ab response at the time of infection. These studies significantly strengthen previous findings, which showed that protection by the J8-diphtheria toxoid vaccine is Ab-mediated and suggest that in vaccine design for other organisms the source of T cell help for Ab responses need not be limited to sequences from the organism itself.

Humoral and cellular factors of maternal immunity in swine

Immunoglobulins cannot cross the placenta in pregnant sows. Neonatal pigs are therefore agammaglobulinemic at birth and, although immunocompetent, they cannot mount rapid immune responses at systemic and mucosal sites. Their survival depends directly on the acquisition of maternal immunity via colostrum and milk. Protection by maternal immunity is mediated by a number of factors, including specific systemic humoral immunity, involving mostly maternal IgG transferred from blood to colostrum and typically absorbed within the first 36 h of life. Passive mucosal immunity involves local humoral immunity, including the production of secretory IgA (sIgA), which is transferred principally via milk until weaning. The mammary gland (MG) produces sIgA, which is, then secreted into the milk via the poly-Ig receptor (pIgR) of epithelial cells. These antibodies are produced in response to intestinal and respiratory antigens, including pathogens and commensal organisms. Protection is also mediated by cellular immunity, which is transferred via maternal cells present in mammary secretions. The mechanisms underlying the various immunological links between MG and the mucosal surfaces involve hormonally regulated addressins and chemokines specific to these compartments. The enhancement of colostrogenic immunity depends on the stimulation of systemic immunity, whereas the enhancement of lactogenic immunity depends on appropriate stimulation at induction sites, an increase in cell trafficking from the gut and upper respiratory tract to the MG and, possibly, enhanced immunoglobulin production at the effector site and secretion in milk. In addition, mammary secretions provide factors other than immunoglobulins that protect the neonate and regulate the development of mucosal immunity--a key element of postnatal adaptation to environmental antigens.

The magnitude of the antibody and memory B cell responses during priming with a protein-polysaccharide conjugate vaccine in human infants is associated with the persistence of antibody and the intensity of booster response

Rapid waning of anti-polysaccharide bactericidal Ab and vaccine effectiveness is observed following infant immunization with the serogroup C meningococcal (MenC) glycoconjugate vaccine. This is despite the demonstrable presence of immunological memory. Persistence of functional Ab, therefore, appears to be the key determinant of MenC conjugate vaccine effectiveness. Ab persistence is thought to depend in the short term on the survival of plasma cells generated during priming and in the longer term on the production of new Ab secreting cells from memory B cells. In this study, we found a strong association between the level of MenC-specific Ab and the frequency of memory B cells measured at 5 mo of age (1 mo after 3-dose primary immunization with MenC conjugate vaccine), and the persistence of functional Ab at one year of age. These findings suggest that these two parameters are good markers of B cell responses to priming and can be used as predictors of long term humoral immunity induced by glycoconjugate vaccines received in early infancy.

An in vivo approach to structure activity relationship analysis of peptide ligands

PURPOSE

The goals in this study were several-fold. First, to optimize the in vivo phage display methodology by incorporating phage pharmacokinetic properties, to isolate peptides that target the brain microvasculature, and then to build focused libraries to obtain structure activity relationship information in vivo to identify the optimal targeting motif.

MATERIALS AND METHODS

The blood pharmacokinetics of filamentous and T7 phage were evaluated to choose the optimal platform. A randomized peptide library with a motif CX(10)C was constructed in T7 phage and used for in vivo panning. Focused peptide libraries around each structural element of the brain-specific peptide were constructed to perform kinetic structure activity relationship (kSAR) analysis in vivo. To determine potential function, sepsis was induced in mice by LPS administration and four hours later the effect of GST-peptide on adhesion of rhodamine-labelled lymphocytes or CFDA-labelled platelets to pial microvasculature was observed by intravital microscopy.

RESULTS

The blood phamacokinetics of T7 was rapid (half-life of 12 min) which aids the clearance of non-specific phage. In vivo panning in brain enriched for isolates expressing the motif CAGALCY. Kinetic analysis of focused libraries built around each structural element of the peptide provided for rapid pharmacophore mapping. The computer modeling data suggested the peptide showed similarities to peptide mimetics of adhesion molecule ligands. GST-CAGALCY but not GST control protein was able to inhibit the rolling and adhesion of labeled platelets to inflamed pial vasculature. GST-CAGALCY had no effect on lymphocyte adhesion.

CONCLUSIONS

Incorporating normal blood phamacokinetics of T7 phage into in vivo phage display improves the ability to recover targeting peptide motifs and allows effective lead optimization by kSAR. This approach led to the isolation of a brain-specific peptide, CAGALCY, which appears to function as an effective antagonist of platelet adhesion to activated pial microvasculature.

T lymphocytes interact with hepatocytes through fenestrations in murine liver sinusoidal endothelial cells

The liver has an established ability to induce tolerance. Recent evidence indicates that this unique property might be related to its distinctive architecture allowing T cells to be activated in situ independently of lymphoid tissues. Unlike lymph node-activated T cells, liver-activated T cells are short-lived, a mechanism that might contribute to the "liver tolerance effect." Although the potential role of hepatocytes as tolerogenic antigen-presenting cells has been demonstrated, the question as to whether these cells are able to interact with CD8(+) T cells in physiological settings remains controversial. Contradicting the immunological dogma stating that naïve T lymphocytes are prevented from interacting with parenchymal cells within non-lymphoid organs by an impenetrable endothelial barrier, we show here that the unique morphology of the liver sinusoidal endothelial cell (LSEC) permits interactions between lymphocytes and hepatocytes. Using electron microscopy, we demonstrate that liver resident lymphocytes as well as circulating naïve CD8(+) T cells make direct contact with hepatocytes through cytoplasmic extensions penetrating the endothelial fenestrations that perforate the LSECs. Furthermore, the expression of molecules required for primary T cell activation, MHC class I and ICAM-1, is polarized on hepatocytes to the perisinusoidal cell membrane, thus maximizing the opportunity for interactions with circulating lymphocytes. In conclusion, this study has identified, at the ultrastructural level, a unique type of interaction between naïve T lymphocytes and liver parenchymal cells in vivo. These results hold implications for the pathogenesis of viral hepatitis in which hepatocytes may represent the main antigen-presenting cell, and for the development of immune tolerance as lymphocytes pass through the liver.

Candida-induced oral epithelial cell responses

OBJECTIVE

Oropharyngeal candidiasis (OPC), caused by Candida albicans, is the most common oral infection in HIV(+) persons. Oral epithelial cells are considered important for innate host defense against OPC with production of cytokines in response to C. albicans and the ability to inhibit Candida growth in vitro. The purpose of this study was to determine if Candida similarly induces cytokines by oral epithelial cells from HIV(+) persons, including those with OPC, as well as to determine if cytokines can influence the oral epithelial cell anti-Candida activity.

METHODS

Supernatants from oral epithelial cells from HIV(+) persons with and without OPC cultured with Candida were evaluated for cytokines by ELISA, or cytokines were added to the standard growth inhibition assay using epithelial cells from HIV(-) persons.

RESULTS

Results showed low Candida-induced epithelial cell cytokine production from HIV(+) persons, but with some elevated proinflammatory cytokines (TNF-alpha, IL-6) in those with OPC compared to those without OPC. The addition of specific proinflammatory or Th cytokines had no effect on oral epithelial cell anti-Candida activity in healthy HIV(-) persons.

CONCLUSION

These results suggest that oral epithelial cells from HIV(+) persons can contribute at some level to the oral cytokine milieu in response to Candida during OPC, but that cytokines do not appear to influence oral epithelial cell anti-Candida activity.

Effect of Plantago major on cell proliferation in vitro

Plantago major (Plantaginaceae) is popularly used to treat tumors, infections and as a blood purifier. Aqueous, methanol, chloroform and hexane extracts of the aerial parts (leaves and seeds) were added to CD(1) mice bone marrow and spleen cultures incubated at 37 degrees C for 72h, and also added to Escherichia coli, Bacillus subtilis and Candida albicans cultures, while methanol extract dilutions were added to HTC-15, OVCAR, UISO and KB cell line cultures. Doses of 0.4 and 0.2 mg/mL of aqueous and methanol extracts increased the bone marrow cell concentration by 2.70- and 3.15-fold, respectively, and increased the spleen cell concentration by 3.38- and 6.39-fold, respectively (p < 0.001). Aqueous extract inhibited Bacillus subtilis growth from 78 to 21%; hexane extract inhibited the growth of Escherichia coli, and methanol and chloroform extracts weakly inhibited the growth of Bacillus subtilis and Escherichia coli, respectively. Methanol extract (1 microg/mL) decreased the UISO and OVCAR cell concentrations to 59 and 82%, respectively. Data demonstrate for the first time that Plantago major has hematopoietic activity in vitro.

Molecular identification of PAL-E, a widely used endothelial-cell marker

The pathologische anatomie Leiden-endothelium (PAL-E) antibody has been used for almost 20 years as a specific marker for vascular endothelial cells. Due to the fact that this antibody works only in very limited applications, the molecular identity of PAL-E has remained unknown. In this work, we demonstrate by double stainings, cross-immunoprecipitations, and transfectants that the PAL-E antigen is identical with a protein designated PV-1 (plasmalemmal vesicle 1) or FELS (fenestrated endothelial-linked structure protein) and is not vimentin, as reported earlier. As the expression of this molecule is by no means restricted to fenestrated endothelium, we suggest the use of the name PLVAP for this protein. Molecular identification of PLVAP should help in the production of new tools for the identification of vascular as opposed to lymphatic endothelium and to elucidate the function of this protein.

Carbohydrates located on the top of the "cap" contribute to the adhesive and enzymatic functions of vascular adhesion protein-1

Vascular adhesion protein 1 (VAP-1) is an endothelial adhesion molecule with an enzymatic activity. It deaminates biogenic amines, resulting in the formation of aldehydes and hydrogen peroxide. During the enzymatic reaction a transient Schiff base is formed between endothelial VAP-1 and its leukocytic ligand, and this interaction is important for lymphocyte adhesion. VAP-1 monomer has six potential N-linked, and three putative O-linked glycosylation sites and an SSSS sequence potentially forming an attachment site for an adjacent O-linked site. In this work we modeled the carbohydrate decorations on a structural model of VAP-1, and studied which of those potential glycosylation sites are utilized, and whether those decorations accessible to a lymphocyte ligand are important in lymphocyte adhesion and enzymatic activity of VAP-1. We show that, unlike the O-linked attachment sites, all six N-linked glycosylation sites are in use. Furthermore, mutation of the N-linked attachment sites strategically located on the top of the molecule reduces lymphocyte adhesion in non-static conditions, and enhances the catalytic activity of membrane-bound human VAP-1 in static conditions, suggesting that glycosylation regulates the functional properties of VAP-1.

Expression of lymphocyte homing and adhesion molecules during intramammary infection of cows with Serratiamarcescens or Streptococcusuberis: correlation with bacterial colonization and clinical signs

We wished to determine the expression of trafficking/adhesion molecules on the surface of lymphocytes isolated from infected mammary glands of cows challenged with either Serratia marcescens or Staphylococcus uberis. Healthy Holstein cows in mid lactation were infected by intramammary infusion with S. marcescens or S. uberis. Following infection, milk samples were collected at various time points. Body temperatures of the cows were taken, and milk was analyzed for colony forming units (CFU) of bacteria and somatic cell counts (SCC). Leukocytes were isolated from the milk and analyzed by flow cytometry. Percentages and types of lymphocytes were determined as well as expression of CD62L, CD11a, LPAM-1 and CD44 on these cells. We found that the percentage of lymphocytes expressing either CD62L or CD11a showed a marked increase 12 h post infection (PI) with S. marcescens that was not seen in cows infected with S. uberis. Conversely, the percentage of lymphocytes expressing CD44 increased in cows infected with S. uberis at 12 h PI, but the increase was not seen in cows infected with S. marcescens. Expression of LPAM-1 was low at all time points in both groups of cows. Body temperatures became elevated in both groups of cows, peaking at 24 h PI in S. marcescens-infected cows and dropping thereafter. In contrast, temperatures of S. uberis-infected cows continued to rise and were still elevated 96 h PI. CFU of bacteria isolated from mammary glands of S. marcescens-infected cows dropped precipitously 24 h PI but continued at high levels in S. uberis-infected cows. SCC began falling in S. marcescens-infected cows 48 h PI but continued to increase in S. uberis-infected cows. Thus, a greater percentage of lymphocytes in milk had a phenotype consistent with recruitment from the peripheral pool following infection with S. marcescens than was seen following infection with S. uberis. Concurrent with the increases seen in percentages of this lymphocyte phenotype, clinical signs lessened in the S. marcescens-infected cows.

Characterization of CD8+ T cells and microenvironment in oral lesions of human immunodeficiency virus-infected persons with oropharyngeal candidiasis

Oropharyngeal candidiasis (OPC), the most common oral infection in human immunodeficiency virus-positive persons, correlates with reduced blood CD4+ T cells. In those with OPC, CD8+ T cells accumulate at the lamina propria-epithelium interface at a distance from the organism at the outer epithelium. The present study aimed to characterize the tissue-associated CD8+ T cells and tissue microenvironment in both OPC+ and OPC- persons. The results show that the majority of CD8+ T cells possess the alphabeta T-cell receptor, the thymus-derived alphabeta CD8 antigen heterodimer, and similar levels of the alpha(4)beta(7), alpha(4)beta(1), and alpha(e)beta(7) homing receptors. Studies to evaluate the tissue microenvironment showed that in OPC+ persons, the adhesion molecule for T cells to enter mucosa, mucosal addressin cell adhesion molecule, is significantly increased, whereas E-cadherin, which allows T cells to migrate through mucosa, is significantly decreased compared to OPC- persons. These results continue to support a role for CD8+ T cells against OPC under conditions of reduced numbers of CD4+T cells, with susceptibility to infection potentially associated with a dysfunction in mucosal CD8+ T-cell migration by reduced tissue-associated E-cadherin.

Chemokines: control of primary and memory T-cell traffic

Motility is a hallmark of leukocytes, and breakdown in the control of migration contributes to many inflammatory diseases. Chemotactic migration of leukocytes largely depends on adhesive interaction with the substratum and recognition of a chemoattractant gradient. Chemokines are secreted proteins and have emerged as key controllers of integrin function and cell locomotion. Numerous distinct chemokines exist that target all types of leukocytes, including hematopoietic precursors, leukocytes of the innate immune system, as well as naive memory, and effector lymphocytes. The combinatorial diversity in responsiveness to chemokines ensures the proper tissue distribution of distinct leukocyte subsets under normal and pathological conditions. Inflammatory chemokines are readily detected in lesional tissue and local cellular infiltrates carry corresponding chemokine receptors. Blocking of inflammatory chemokines represents a promising strategy for the development of novel anti-inflammatory therapeutics. This review focuses on a separate class of chemokines, termed homeostatic chemokines, with steady-state production at diverse sites, including primary and secondary lymphoid tissues as well as peripheral (extralymphoid) tissues. More precisely, we discuss the chemokines involved in T-cell traffic during the initiation of adaptive immunity and compare the distinct migration properties of short-lived effector T cells and long-lived memory T cells. Memory T cells are currently classified according to the presence of the lymph node-homing receptor CCR7 into CCR7+ central memory T (T(CM)) cells and CCR7- effector memory T (T(EM)) cells. For better understanding memory T-cell function, we propose the distinction of a third category, termed peripheral immune surveillance T (T(PS)) cells, which typically reside in healthy peripheral tissues, such as skin, lung, and gastrointestinal tract. Localization and relocation of memory T cells is strictly related to their function in recall responses. Therefore, detailed knowledge of their generation and tissue distribution may help to design better vaccination strategies.

Increased Fas ligand expression of CD4+ T cells by HCV core induces T cell-dependent hepatic inflammation

Hepatitis C virus (HCV) infection is associated with a high rate of viral persistence and the development of chronic liver disease. The expression of HCV core protein in T cells has previously been reported to alter T cell activation and has been linked to the development of liver inflammation. However, the molecular and cellular basis for the role of HCV core-expressing T cells in liver inflammation is not understood. Here, using double-transgenic mice of CD2/HCV-core transgenic mice and ovalbumin (OVA)-specific T cell receptor transgenic mice, we demonstrated that in vivo antigenic stimulation (OVA peptide administration) triggers a marked influx of core-expressing, antigen-specific, transgenic CD4+ T cells into the liver of these mice. Phenotypic analysis of the liver-infiltrating T cells revealed high expression levels of CD44 and Fas ligand (FasL). Adoptive transfer of liver-infiltrating, core-expressing CD4+ T cells into severe combined immunodeficiency mice directly demonstrated the capacity of these activated T cells to induce liver inflammation. It is important that anti-FasL antibody treatment of the mice at the time of cell transfer abrogated the liver inflammation induced by core-expressing CD4+ T cells. These findings suggest that activated T lymphocytes expressing elevated levels of FasL may be involved in the bystander killing of hepatocyte, as well as the induction of chronic liver inflammation, by promoting recruitment of proinflammatory cells to the liver.

Adhesion molecule and homing receptor expression on blood and milk polymorphonuclear leukocytes during the periparturient period of dairy cattle

Adhesion molecule and homing receptor expression on blood and milk polymorphonuclear leukocytes (PMN) from periparturient dairy cattle was studied. Both percentages and the mean fluorescence intensity (MFI) of PMN expressing CD11a, CD44, CD62L, and LPAM-1 (alpha4 beta7) were evaluated at seven time points during the twenty-one day period post calving. CD11a and CD62L were expressed on 94-100% of PMN in both blood and milk and there were no significant differences in these percentages at any time point. LPAM-1 was expressed on 3-10% of the PMN in the blood and 13-45% in the milk and the percentage of cells expressing LPAM-1 in milk was significantly (P<0.05) greater than in blood at 0, 4, 10, 14, 18 and 21 days after calving. CD44 was expressed on 11-39% of the PMN in blood and 33-69% in the milk and the percentage of cells expressing CD44 in milk was significantly (P<0.05) greater than in blood at all time points. The MFI of CD11a on milk PMN was consistently higher than that of blood PMN throughout the study period and significantly (P<0.05) higher at days 4, 10 and 18 after calving.

A novel method to isolate and map endothelial membrane proteins from pulmonary vasculature

Vascular endothelium has attracted extensive attention due to its important role in many physiological and pathological processes. Many methods have been developed to study the components and their functions in vascular endothelium. Here we report a novel approach to investigate vascular endothelium using normal rat lungs as the model. We perfused lung vascular beds with sulfosuccinimidyl-6-(biotinamido) hexanoate, a biotin analog, to label endothelial membrane proteins. The biotinylated proteins were isolated from lung homogenate with immobilized monomeric avidin and confirmed to be highly pure endothelial membrane proteins with little contamination of intracellular proteins. These biotinylated proteins were used as immunogens for development of monoclonal antibodies. Indeed, newly generated monoclonal antibodies have revealed different expression patterns of proteins across tissues. Some proteins were found highly specifically expressed to capillary vessels of pulmonary vasculature. This method has also been proven useful for investigating vasculature of other organs, as this study explored.

Lymphocyte subsets and adhesion molecule expression in milk and blood of periparturient dairy cattle

Fifteen Holstein dairy cattle were monitored for lymphocyte subsets and expression of adhesion molecules on cells in milk and blood at parturition and at intervals up to 21 days post-partum. Using flow cytometry, we determined percentages of T cells (CD4+, CD8+, gammadelta) and B cells from milk and blood of these cows. We also measured expression of adhesion molecules (CD62L, LFA-1, LPAM-1, and CD44) on lymphocytes in milk and blood. Significantly higher percentages of CD8+ cells were found in milk than in blood at all time points while significantly higher percentages of B cells were found in blood than in milk at all time points. There were minimal to no significant differences in percentages of CD4+ or gammadelta+ cells between milk and blood. Expression of adhesion molecules was consistently higher on all subsets of milk lymphocytes compared with blood lymphocytes. These differences were most pronounced and statistically significant at calving and in the first week following calving. CD62L, LPAM-1 and CD44 were expressed on a significantly higher percentage of lymphocytes in milk at calving than in milk at subsequent sampling times, while LFA-1 expression on lymphocytes in milk was significantly lower at calving than at subsequent times.

The Immunization Site of Cytokine-Secreting Tumor Cell Vaccines Influences the Trafficking of Tumor-Specific T Lymphocytes and Antitumor Efficacy against Regional Tumors

Tumor cells engineered to secrete cytokines, referred to as tumor cell vaccines, can often generate systemic antitumor immunity and, in many cases, cause tumor regression. We compared the efficacy of s.c. immunization or intrahepatic immunization of GM-CSF-expressing tumor cell vaccines on the growth of s.c. or orthotopic liver tumors. A chemically transformed hepatic epithelial cell line, GP7TB, derived from Fischer 344 rats, was used to generate tumor models and tumor cell vaccines. Our results demonstrated that two s.c. injections of an irradiated tumor cell vaccine significantly controlled the growth of s.c. tumors, but was completely ineffective against orthotopic liver tumors. Effector cell infiltration in liver tumors was markedly reduced compared with s.c. tumors. Enhanced apoptosis of some effector cells was observed in the liver tumors compared with the s.c. tumors. Furthermore, the T cells induced by s.c. immunization preferentially migrated to s.c. tumor sites, as demonstrated by adoptive transfer experiments. In contrast, intrahepatic immunization, using parental tumor cells admixed with adenoviruses carrying the GM-CSF gene, yielded significantly better therapeutic effects on the liver tumors than on the s.c. tumors. Adoptive transfer experiments further confirmed that the T cells induced by liver immunization preferentially migrated to the liver tumor sites. Our results demonstrate that distinct T cell populations are induced by different immunization routes. Thus, the homing behavior of T cells depends on the route of immunization and is an important factor determining the efficacy of immunotherapy for regional tumors.

Tracking the follicular lymphoma cells in flow cytometry: characterisation of a new useful antibody combination

OBJECTIVES

Follicular lymphoma (FL) is the most common adult non-Hodgkin's lymphoma. Diagnosis is based on morphology and can be confirmed by cytogenetic, flow cytometry (FCM) or molecular studies. Despite all these complementary approaches, diagnosis sometimes remains difficult. The purpose of the present work was to characterise the expression of new specific follicular cells markers which allows us to target specifically the abnormal FL cell population in FCM.

METHODS

A total of 153 samples from healthy subjects and from patients with chronic B-cell lymphoproliferative disorders were analysed by FCM in the same conditions for purpose of comparison.

RESULTS

We showed that CD44 is weakly expressed in FL cells compared with peripheral blood mononuclear cell from normal blood donors and others cells from B lymphoproliferative diseases. We nevertheless observed bone marrow samples where some immature B-cell population express CD44 with lower fluorescence intensity. Therefore, we developed a double antibody combination, using CD44 and CD38, which allowed us to separate the normal immature cells from the pathological population using FCM.

CONCLUSION

This new phenotypic approach offers an accurate (sensitivity and specificity of 93% and 96%, respectively), fast and low sample consuming method for the diagnosis of FL.

Reactive arthritis. Immune-mediated synovitis or joint infection

Reactive arthritis is one form of the seronegative Spondyloarthropathies. Susceptibility to reactive arthritis is closely linked to individuals who have the genetic predisposition to the HLA-B27 allele (gene form). Although there is a reactive-inflammatory joint reaction present, the synovium is not damaged by infectious agents (bacteria, fungi, or virus). This article discusses the pathogenesis of reactive arthritis.

CLEVER-1 mediates lymphocyte transmigration through vascular and lymphatic endothelium

Common lymphatic endothelial and vascular endothelial receptor-1 (CLEVER-1; also known as stabilin-1 or FEEL-1) is a large multifunctional glycoprotein implicated in scavenging, angiogenesis, and cell adhesion. Here we studied the function of human CLEVER-1 in leukocyte trafficking. Lymphatic vessels expressed CLEVER-1 constitutively in skin in vivo, whereas on vascular endothelium it appeared only upon inflammation. On isolated vascular endothelial cells, CLEVER-1 supported rolling and transmigration of peripheral blood mononuclear cells (PBMCs) under physiologically relevant laminar shear stress. Intriguingly, CLEVER-1 also mediated transmigration of leukocytes through cultured lymphatic endothelium under static conditions. Thus, synthesis of CLEVER-1 is differentially regulated on the 2 anatomically distinct vascular beds, and CLEVER-1 mediates the transmigration step of the leukocyte traffic in both of them. Notably, CLEVER-1 is the first adhesion molecule shown to be involved in the PBMC transmigration through the lymphatic arm of the immune system.

Ligands for L-selectin: homing, inflammation, and beyond

Understanding the molecular basis of lymphocyte homing to lymphoid organs was originally a problem of concern only to immunologists. With the discovery of L-selectin and its ligands, interested scientists have expanded to include glycobiologists, immunopathologists, cancer biologists, and developmental biologists. Going beyond its first discovered role in homing to lymph nodes, the L-selectin system is implicated in such diverse processes as inflammatory leukocyte trafficking in both acute and chronic settings, hematogenous metastasis of carcinoma cells, effector mechanisms for inflammatory demyelination of axons, and implantation of the early mammalian embryo. This review focuses on the ligands for L-selectin that are found on vascular endothelium, leukocytes, carcinoma cells, and at various extravascular sites. The discovery of selectins and their ligands has validated the long-predicted hypothesis that carbohydrate-directed cell adhesion is relevant in eukaryotic systems. Emphasis will be given to the carbohydrate and sulfation modifications of the ligands, which enable recognition by L-selectin. The rapid "homing" of labeled cells into the lymph nodes presumably had its basis in the special affinity of small lymphocytes for the endothelium of the postcapillary venules.

Distribution of 99mTc-labeled lymphocytes in control and inflamed rats

We studied the in vivo fate of CD8(+) lymphocytes, of naive (CD8(+)CD45RC(bright)) or memory (CD8(+)CD45RC(dim)) phenotype, injected in syngeneic rats, after their sorting and labeling with [(99m)Tc] HM-PAO. By using the scintigrafic method we showed that memory CD8(+) lymphocytes were able to recirculate into liver and lungs. The same method was also successfully used to in vivo study the homing of total blood lymphocytes obtained from inflamed rats.

Loss of vascular adhesion protein-1 expression in intratumoral microvessels of human skin melanoma

Intratumoral vessels are different both structurally and phenotypically, and this may have clinical significance. In this study we analysed the expression of an adhesion molecule--vascular adhesion protein-1 (VAP-1)--in melanoma-associated blood vessels in 28 primary skin melanoma cases using immunocytochemistry and immunoelectron microscopy. We have found that VAP-1 protein expression is significantly decreased in intratumoral vessels compared with peritumoral ones; this difference was independent of the tumour thickness. Loss of VAP-1 protein expression occurred in both endothelial and smooth muscle cell components. Unlike in other cancer types, the VAP-1 protein expression of intratumoral vessels did not correlate with the density of cytotoxic T-lymphocytes or dendritic cells. On the other hand, the 5-year survival of melanoma patients with low VAP-1 protein expression in intratumoral blood vessels (< or =25%) was lower (26.3%) than in patients whose VAP-1 expression was higher (42.6%, P=0.0632). These results support the idea that the phenotype of intratumoral blood vessels is important in the progression of malignant melanoma.

Expression of adhesion molecules on milk and blood lymphocytes from periparturient dairy cattle with Johne’s disease

Twelve dairy cows infected with Mycobacterium avium subsp. paratuberculosis were monitored for lymphocyte subsets and expression of adhesion molecules on cells in blood and milk at parturition and at intervals up to 21 days post-partum. Using fluorescent antibody labeling of cells and analysis by flow cytometry, we determined percentages of T cell subsets (CD4+, CD8+, gammadelta+) and expression of adhesion molecules (CD62L, LFA-1, LPAM-1, and CD44) on cells from blood and milk of these cows. Significantly higher percentages of CD8+ cells were found in milk than in blood at all time points; there were no significant differences in percentages of CD4+ or gammadelta+ cells. CD62L, LFA-1, and LPAM-1 were expressed on a significantly higher percentage of all T cell subsets in milk than in blood at various times after parturition. No differences were seen in expression of CD44. Increased percentages of T lymphocytes expressing adhesion molecules in milk compared to blood suggest that a migratory population of cells is being selectively recruited to the mammary gland from the circulation.

Trafficking of Th1 cells to lung: a role for selectins and a P-selectin glycoprotein-1-independent ligand

Trafficking of lymphocytes to lung is a critical component of pulmonary immune defense and surveillance. Selectins, expressed on vascular endothelium, regulate T lymphocyte emigration into tissues, such as skin, but the role of the selectins in trafficking of T cells to lung has not been well characterized. Here, we used a model of lung inflammation induced by adoptive transfer of alloreactive Th1 cells to analyze the role of P- and E-selectin in Th1 cell trafficking to lung in vivo. We found that both P- and E-selectin play an important role in Th1 lymphocyte migration to lung. We confirmed that the Th1 cells express P-selectin glycoprotein ligand-1, which was functional in binding to P- and E-selectin in vitro. However, our studies reveal that a ligand distinct from P-selectin glycoprotein-1 also binds these selectins in vitro and appears to play a physiologic role in in vivo emigration of Th1 lymphocytes into the lung.

TNF-alpha-dependent ICAM-1- and VCAM-1-mediated inflammatory responses are delayed in neonatal mice infected with Pneumocystis carinii

Neonatal mice have a delayed CD4-mediated inflammatory response to Pneumocystis carinii (PC) infection in the lungs that corresponds to a delayed TNF-alpha response and a delayed clearance of the organisms compared with adult mice. Since TNF-alpha is known to drive the up-regulation of adhesion molecules, we examined the expression and function of adhesion molecules in the lungs of neonatal mice. The expression of both ICAM-1 and VCAM-1 was significantly lower in the lungs of PC-infected neonatal mice compared with adults. Additionally, migration of neonatal T cells across endothelial cells expressing VCAM-1 and monocyte chemotactic protein-1 was aberrant compared with that in adult T cells, although alpha(4)beta(1) integrin-mediated adhesion of neonatal lymphocytes was comparable to that of adult lymphocytes. Treatment of neonatal mice with exogenous TNF-alpha resulted in increased expression of ICAM-1 and VCAM-1 as well as increased expression of chemokines, resulting in infiltration of CD4(+) cells into the lungs. Treatment with exogenous TNF-alpha resulted in a trend (although not statistically significant) toward a reduction of PC organisms from the lungs. These data indicate that neonatal lung endothelial cells do not up-regulate ICAM-1 and VCAM-1 in response to PC infection, probably due to depressed TNF-alpha production. Additionally, neonatal T cells are defective in the ability to migrate across endothelial cells.

Granulocyte transmigration through the endothelium is regulated by the oxidase activity of vascular adhesion protein-1 (VAP-1)

Polymorphonuclear leukocytes (PMNs) migrate from the blood into areas of inflammation by binding to the endothelial cells of blood vessels via adhesion molecules. Vascular adhesion protein-1 (VAP-1) is one of the molecules mediating leukocyte-endothelial cell interactions. It is also an endothelial cell-surface enzyme (amine oxidase) that produces reactive oxygen species during the catalytic reaction. To study the role of the enzymatic activity of VAP-1 in PMN extravasation, we used an enzymatically inactive VAP-1 mutant, specific amine oxidase inhibitors (including a novel small molecule compound), and anti-VAP-1 antibodies in several flow-dependent models. The enzyme inhibitors diminished PMN rolling on and transmigration through human endothelial cells under conditions of laminar shear stress in vitro. Notably, the enzyme inactivating point mutation abolished the capacity of VAP-1 to mediate transmigration. Moreover, the new VAP-1 inhibitor effectively prevented the extravasation of PMNs in an animal model of inflammation. These data show that the oxidase activity of VAP-1 controls PMN exit from the blood during the relatively poorly understood transmigration step.

Role of ?4 integrin and its ligand VCAM-1 in the specific extravasation of a tumor-specific TH2 clone into tumor tissue that initiates its rejection

The effectiveness of anticancer immunotherapeutic strategies involving the transfer of tumor-specific T cells depends on appropriate lymphocyte-endothelial cell interactions that facilitate the migration of lymphocytes into tumor. Here, we investigated the molecular mechanisms underlying the migration of the antigen-specific Th2 CD4(+) T-cell clone YS1093 into S1509a tumor tissue. YS1093 is specific for the S1509a tumor but does not recognize the S713a tumor. Transfer of YS1093 cells into mice bearing both S1509a and S713a tumors caused only the S1509a tumor to regress. This regression was markedly inhibited by pretreating YS1093 cells with an anti-alpha4 integrin MAb and administering an anti-VCAM-1 MAb at T-cell transfer. Since vascular endothelial cells in S1509a tumor tissues express VCAM-1 and the MHC class II (I-E(k)) molecule restricting YS1093 activity, labeled YS1093 cells migrated specifically into the S1509a tumor, and this migration was also blocked by the anti-TCRbeta F(ab')(2) and anti-I-E(k) MAbs. Furthermore, in vitro assays revealed that anti-CD3 MAb-mediated TCR cross-linkage initiated the binding of alpha4 integrin on YS1093 cells to VCAM-1. This adhesive activity was completely blocked by the anti-alpha4 integrin MAb. These results strongly suggest that i.v.-transferred YS1093 cells act in tumor regression by specifically recognizing their tumor antigen peptide in the context of I-E(k) on vascular endothelial cells in the S1509a tumor, which activates the binding of alpha4 integrin to VCAM-1 on the endothelial cells, facilitating YS1093 extravasation into the tumor. It is likely that this initial migration of specific CD4(+) T cells into tumor tissues promotes the subsequent infiltration into the tumor of other immunocytes that effect tumor destruction.

Insulin-regulated increase of soluble vascular adhesion protein-1 in diabetes

Vascular adhesion protein-1 (VAP-1) is one of the molecules on the endothelial cell membrane, which may guide inflammatory cells into atherosclerotic lesions. This dual function molecule may also contribute to the pathogenesis of atherosclerosis and other vasculopathies via its enzymatic activity that oxidizes primary amines to produce their corresponding aldehydes, hydrogen peroxide, and ammonium. Because VAP-1 also exists in a soluble form, we analyzed its potential usefulness as a biomarker to monitor and predict the extent of ongoing atherosclerotic processes. Soluble VAP-1 (sVAP-1) levels were determined from the sera of 136 Finnish men with established coronary heart disease and in 275 controls using sandwich enzyme immunoassays and correlated to multiple risk factors for coronary events. Intriguingly, sVAP-1 showed a statistically significant correlation with diabetes in both cohorts. We then collected patients with type 1 diabetes and observed that sVAP-1 levels were highly elevated when the patients were metabolically compromised. On normalization of their blood glucose and ketone body levels by exogenous insulin, their sVAP-1 concentration rapidly decreased to control levels. Intravenous glucose tolerance and hyperinsulinemic clamp tests further showed that elevation of blood glucose per se did not increase sVAP-1 levels, but rather, sVAP-1 was inversely correlated with circulating insulin concentrations. In conclusion insulin appears to regulate shedding or clearance of VAP-1, and an increase in sVAP-1 because of absolute or relative insulin deficiency may be directly involved in the pathogenesis of diabetic angiopathy.

Skin-homing CLA+ T cells and regulatory CD25+ T cells represent major subsets of human peripheral blood memory T cells migrating in response to CCL1/I-309

Functionally distinct T cell subsets exhibit specific chemokine receptor profiles that regulate their tissue localization. Here, we show that human peripheral blood CD4(+) and CD8(+) cutaneous (CLA(+)), but not intestinal memory (integrin beta(7) (+)) nor IL-4-producing T cells, represent major subpopulations of circulating T cells that specifically migrate in response to the chemokine I-309/CCL1 by virtue of CCR8 expression. Expression of CCR8 is markedly up-regulated upon activation and in vitro culture of human CLA(+) T cells, suggesting the involvement of CCR8 in localization of cutaneous memory T cells to the skin. Interestingly, amongst circulating memory CD4(+)CD45RO(+) T cells, chemotactic responsiveness to CCL1 is restricted to cells expressing CD25 and/or CLA surface markers for regulatory T cells (Treg) and skin-homing T cells and maximal responsiveness is observed on CLA(+)CD25(+)T cells. Such pattern of CCL1 responsiveness suggests that the CCR8/CCL1 axis may regulate trafficking of cutaneous Treg and memory T cells into the skin.

Junctional adhesion molecule-2 (JAM-2) promotes lymphocyte transendothelial migration

The molecular mechanisms underlying lymphocyte extravasation remain poorly characterized. We have recently identified junctional adhesion molecule-2 (JAM-2), and have shown that antibodies to JAM-2 stain high endothelial venules (HEVs) within lymph nodes and Peyer patches of adult mice. Here we show that mouse lymphocytes migrate in greater numbers across monolayers of endothelioma cells transfected with JAM-2. The significance of these findings to an understanding of both normal and pathologic lymphocyte extravasation prompted us to clone the human homologue of JAM-2. We herein demonstrate that an anti-JAM-2 antibody, or a soluble JAM-2 molecule, blocks the transmigration of primary human peripheral blood leukocytes across human umbilical vein endothelial cells expressing endogenous JAM-2. Furthermore, we show that JAM-2 is expressed on HEVs in human tonsil and on a subset of human leukocytes, suggesting that JAM-2 plays a central role in the regulation of transendothelial migration.

Corrigendum to "The sow endometrium at different stages of the oestrus cycle: studies on morphological changes and infiltration by cells of the immune system." [Anim. Reprod. Sci. 65 (2001) 95-114]

The aim of this study was to investigate the distribution of leukocytes and the morphological changes of the sow endometrium throughout the oestrous cycle. Fifteen crossbred multiparous sows (Swedish Landrace x Swedish Yorkshire), with an average parity number of 3.4+/-0.7 (mean+/-S.D.) were used. Blood samples were collected from the jugular vein 1 h before slaughter for analyses of oestradiol-17beta and progesterone levels. Uterine samples from the mesometrial side of both horns, taken immediately after slaughter at late dioestrus, prooestrus, oestrus, early dioestrus and dioestrus, were fixed, embedded in plastic resin and stained with toluidine blue. The surface and glandular epithelium as well as subepithelial and glandular connective tissue layers were examined by light microscopy (LM). The significantly highest surface and the glandular epithelium were observed at oestrus and dioestrus, respectively. The largest number of capillaries (underneath the surface epithelium) was found at oestrus. In the surface epithelium, the largest number of intraepithelial lymphocytes (IELs, round nucleus) was found at early dioestrus. The largest number of lymphocytes and macrophages within the glandular epithelium were found at early dioestrus and oestrus, respectively. In the subepithelial connective tissue layer, the most common type of leukocytes during all stages was the lymphocyte. The largest numbers of lymphocytes and neutrophils were found at oestrus while the largest number of eosinophils was found at dioestrus. The dominating cells of the immune system in the connective tissue of the glandular layer were lymphocytes and macrophages. The significantly largest numbers of lymphocytes and plasma cells were found at early dioestrus and dioestrus, respectively. The number of lymphocytes in the connective tissue of the glandular layer and the number of plasma cells in the subepithelial layer were positively correlated with the plasma level of progesterone (P < or = 0.05). The numbers of capillaries and neutrophils in the subepithelial layer underneath the surface epithelium as well as the number of macrophages in both surface and glandular epithelium were positively correlated with the plasma level of oestradiol-17beta (P < or = 0.05). In conclusion, the present study showed a variation om the infiltration and distrobution of lymphocytes, neutrophils, eosinophils, macrophages, mast cells, and plasma cells in the sow endometrium during different stages of the oestrous cycle. Also morphological parameters (e.g. height of surface and glandular epithelium, capillaries density and degree of oedema) varied throughout the oestrous cycle.

Lymphoproliferative responses and protection in conventional piglets inoculated orally with virulent or attenuated porcine epidemic diarrhoea virus

Lymphocyte proliferative responses were evaluated in mucosal (mesenteric lymph nodes) and systemic (spleen and blood) lymphoid tissues of conventional piglets inoculated with the virulent or attenuated isolates of porcine epidemic diarrhoea virus (PEDV) strain CV-777 and challenged 21 days later with the virulent isolate of the same virus. A lymphoproliferative assay was developed in which mononuclear cells isolated from lymphoid tissues at different postinoculation and postchallenge days underwent a secondary in vitro stimulation with semipurified antigen obtained from PEDV-infected cell cultures. Vigorous lymphocyte proliferative responses were detected in the pigs inoculated with the virulent PEDV at postinoculation days 4-21, especially in the mesenteric lymph nodes and the blood; however, in the spleen this response was lower and less regular. The pigs inoculated with the attenuated virus showed a less intense response, the higher lymphocyte proliferation also corresponded to the mononuclear cells from mesenteric lymph nodes. Lymphocyte proliferation responses showed high correlations with protection against homologous challenge with virulent PEDV, and this correlation was higher in the gut associated lymphoid tissues (mesenteric lymph nodes). The cell proliferation response detected in blood mirrored that detected in the mesenteric lymph nodes, and showed also good correlation with protection. The results confirm that T-cell-helper function, assessed by lymphocyte proliferation responses, contributes to establishing a protective immune response against PEDV infections.

Identification of synovium-specific homing peptides by in vivo phage display selection

OBJECTIVE

To identify homing peptides specific for human synovium that could be used as targeting devices for delivering therapeutic/diagnostic agents to human joints.

METHODS

Human synovium and skin were transplanted into SCID mice. A disulfide-constrained 7-amino acid peptide phage display library was injected intravenously into the animals and synovial homing phage recovered from synovial grafts. Following 3-4 cycles of enrichment, DNA sequencing of homing phage clones allowed the identification of specific peptides that were synthesized by a-fluorenylmethyloxycarbonyl chemistry and used in competitive in vivo assays and immunohistochemistry analyses.

RESULTS

We isolated synovial homing phages displaying specific peptides that distinctively bound to synovial but not skin or mouse microvascular endothelium (MVE). They retained their tissue homing specificity in vivo, independently from the phage component, the original pathology of the transplanted tissue, and the degree of human/murine graft vascularization. One such peptide (CKSTHDRLC) maintained synovial homing specificity both when presented by the phage and as a free synthetic peptide. The synthetic peptide also competed with and inhibited in vivo the binding of the parent phage to the cognate synovial MVE ligand.

CONCLUSION

This is the first report describing peptides with homing properties specific for human synovial MVE. This was demonstrated using a novel approach targeting human tissues, transplanted into SCID mice, directly by in vivo phage display selection. The identification of such peptides opens the possibility of using these sequences to construct joint-specific drug delivery systems that may have considerable impact in the treatment of arthritic conditions.