Search

I provide a narrative of the path I took to discover the membrane receptors that mediate leukocyte adhesion, now known as ß2 integrins or CD11/CD18. We followed this discovery with the first determination of the 3-D structures of integrins. The latter advance provided the foundation for understanding the unique features of integrins as divalent cationdependent signaling receptors and as mechanosensitive conduits between the extracellular matrix and the intracellular cytoskeleton. Our structural studies are now opening new paths for taming overactive integrins in disease while minimizing the collateral damage associated with the faulty pharmacodynamics of current integrin inhibitory drugs. [ABSTRACT FROM AUTHOR]

Background: Immunophenotyping has a central role in CLL. However, CLL is a very heterogenous disease, both morphologically and immunophenotypically; thus, its diagnosis may prove a challenge. We investigated CD81 expression in the differential diagnosis of CLL and MCL. Methods: We retrospectively examined CD81 expression with 8 color Multiparameter Flow cytometry devices in 101 CLL and 19 MCL cases. Results: We found negative CD81 expression in CLL cases whereas it was positive in MCL cases. Conclusions: Our results suggest that CD81 may be a valuable marker for the differential diagnosis of CLL. We are of the opinion that it should be definitely included in the diagnostic algorithm for CLL. [ABSTRACT FROM AUTHOR]

Neutrophils and macrophages are important constituents of the hepatic inflammatory infiltrate in non-alcoholic steatohepatitis. These innate immune cells express CD18, an adhesion molecule that facilitates leukocyte activation. In the context of fatty liver, activation of infiltrated leukocytes is believed to enhance hepatocellular injury. The objective of this study was to determine the degree to which activated innate immune cells promote steatohepatitis by comparing hepatic outcomes in wild-type and CD18-mutant mice fed a methionine-choline-deficient (MCD) diet. After 3 weeks of MCD feeding, hepatocyte injury, based on serum ALT elevation, was 40% lower in CD18-mutant than wild-type mice. Leukocyte infiltration into the liver was not impaired in CD18-mutant mice, but leukocyte activation was markedly reduced, as shown by the lack of evidence of oxidant production. Despite having reduced hepatocellular injury, CD18-mutant mice developed significantly more hepatic steatosis than wild-type mice after MCD feeding. This coincided with greater hepatic induction of pro-inflammatory and lipogenic genes as well as a modest reduction in hepatic expression of adipose triglyceride lipase. Overall, the data indicate that CD18 deficiency curbs MCD-mediated liver injury by limiting the activation of innate immune cells in the liver without compromising intrahepatic cytokine activation. Reduced liver injury occurs at the expense of increased hepatic steatosis, which suggests that in addition to damaging hepatocytes, infiltrating leukocytes may influence lipid homeostasis in the liver. [ABSTRACT FROM AUTHOR]

Background Leukocyte adhesion deficiency ( LAD) or CD18 deficiency is an autosomal recessive immunodeficiency which has been described in people, cattle, dogs, and knockout mice. Objectives The study goals were to characterize the clinicopathologic, immunologic, and molecular genetic features of feline LAD ( FLAD) in a neutered male adult Domestic Longhair cat with severe leukocytosis and recurrent infections. Methods Flow cytometry evaluated surface expression of CD18 on neutrophils. In vitro functional assays assessed CD18-dependent neutrophil adhesion and T-cell proliferation. Genomic DNA and cDNA were used to identify a causative mutation in the coding sequence of the integrin β2 subunit ( ITGB2) gene. Results The affected cat developed periodontitis during the first months of life followed by recurrent infections poorly responsive to antibiotic therapy, accompanied by extreme neutrophilia. Neutrophils from the proband, compared to feline controls, did not express any CD18 on the cell surface. Adhesion of affected neutrophils was severely impaired with and without phorbol-myristate-acetate activation. The proband's T-cells proliferated weakly to 1 pg but normally to 100 pg staphylococcal enterotoxin A, suggesting a CD18-independent T-cell response at higher doses. Molecular genetic analysis of the ITGB2 gene revealed a 24 bp deletion at the exon 2 to intron 2 boundary (c.46_58 + 11del), predicting premature translational termination due to abnormal splicing of exon 1 to exon 3 or 4. Conclusions Feline LAD exhibits features similar to LAD in other species. However, clinical episodes in FLAD appeared milder allowing for an extended life expectancy under long-term antimicrobial therapy, possibly due to an alternative, CD18-independent T-cell proliferation pathway. [ABSTRACT FROM AUTHOR]

Complement receptor 3 (CR3, CD11b/CD18) is a multi-functional receptor expressed predominantly on myeloid and natural killer (NK) cells. The R77H variant of CD11b, encoded by the ITGAM rs1143679 polymorphism, is associated robustly with development of the autoimmune disease systemic lupus erythematosus (SLE) and impairs CR3 function, including its regulatory role on monocyte immune signalling. The role of CR3 in NK cell function is unknown. Leukadherin-1 is a specific small-molecule CR3 agonist that has shown therapeutic promise in animal models of vascular injury and inflammation. We show that Leukadherin-1 pretreatment reduces secretion of interferon (IFN)-γ, tumour necrosis factor (TNF) and macrophage inflammatory protein (MIP)-1β by monokine-stimulated NK cells. It was associated with a reduction in phosphorylated signal transducer and activator of transcription (pSTAT)-5 following interleukin (IL)-12 + IL-15 stimulation ( P < 0·02) and increased IL-10 secretion following IL-12 + IL-18 stimulation ( P < 0·001). Leukadherin-1 pretreatment also reduces secretion of IL-1β, IL-6 and TNF by Toll-like receptor (TLR)-2 and TLR-7/8-stimulated monocytes ( P < 0·01 for all). The R77H variant did not affect NK cell response to Leukadherin-1 using ex-vivo cells from homozygous donors; nor did the variant influence CR3 expression by these cell types, in contrast to a recent report. These data extend our understanding of CR3 biology by demonstrating that activation potently modifies innate immune inflammatory signalling, including a previously undocumented role in NK cell function. We discuss the potential relevance of this to the pathogenesis of SLE. Leukadherin-1 appears to mediate its anti-inflammatory effect irrespective of the SLE-risk genotype of CR3, providing further evidence to support its evaluation of Leukadherin-1 as a potential therapeutic for autoimmune disease. [ABSTRACT FROM AUTHOR]

The article presents a study which discusses lentiviral vector-mediated correction of a mouse model of Leukocyte adhesion deficiency type I (LAD-I). Topics discussed include use of mouse model of LAD-I with a hypomorphic mutation in CD18, preparation of lipopolysaccharide-induced asthma model, and use of Genomic DNA (gDNA) for vector copy number (VCN) determination.

In addition to previously studied immunological variables, the relative expression of IFNGR2, IFNAR1, CD18, and CD275 (all encoded in chromosome 21) on circulating leucocytes and multifunctional T cells (evaluated by an intracellular cytokine/proliferation assay) were compared between children with Down syndrome (DS) and healthy controls (HC). As previously reported, numbers of lymphocytes, CD4 + T cells, Treg cells, B cells, and levels of serum IgM were decreased, and levels of IgG and IgA were increased in children with DS. Moreover, the relative expression of CD18 on T and B cells (previously and not previously reported, respectively) were elevated in DS children (p ⩽ 0.01). Age and numbers of B and Treg cells moderately correlated with retrospectively identified infection related hospitalizations (rho: 0.300–0.460, p ⩽ 0.003). Age and the numbers of Treg cells also correlated with prospectively identified infection related hospitalizations. Future studies are necessary to clarify the role of these parameters in the immunity of DS patients. [ABSTRACT FROM AUTHOR]

Introduction: In rheumatoid arthritis (RA) immune activation and presence of autoantibodies may precede clinical onset of disease, and joint destruction can progress despite remission. However, the underlying temporal changes of such immune system abnormalities in the inflammatory response during treat-to-target strategies remain poorly understood. We have previously reported low levels of the soluble form of CD18 (sCD18) in plasma from patients with chronic RA and spondyloarthritis. Here, we study the changes of sCD18 before and during treatment of early RA and following arthritis induction in murine models of rheumatoid arthritis. Methods: The level of sCD18 was analyzed with a time-resolved immunoflourometric assay in 1) plasma from early treatment naïve RA patients during a treat-to-target strategy (the OPERA cohort), 2) plasma from chronic RA patients, 3) serum from SKG and CIA mice following arthritis induction, and 4) supernatants from synovial fluid mononuclear cells (SFMCs) and peripheral blood mononuclear cells (PBMCs) from 6 RA patients cultured with TNFα or adalimumab. Results: Plasma levels of sCD18 were decreased in chronic RA patients compared with early RA patients and in early RA patients compared with healthy controls. After 12 months of treatment the levels in early RA patients were similar to healthy controls. This normalization of plasma sCD18 levels was more pronounced in patients with very early disease who achieved an early ACR response. Plasma sCD18 levels were associated with radiographic progression. Correspondingly, the serum level of sCD18 was decreased in SKG mice 6 weeks after arthritis induction compared with healthy littermates. The sCD18 levels in both SKG and CIA mice exhibited a biphasic course after arthritis induction with an initial increase above baseline followed by a decline. Shedding of CD18 from RA SFMC and RA PBMC cultures was increased by TNFα and decreased by adalimumab. Conclusions: The plasma sCD18 levels were altered in patients with RA, in mice with autoimmune arthritis and in cell cultures treated with TNFα and adalimumab. Decreased levels of plasma sCD18 could reflect autoimmunity in transition from early to chronic disease and normalization in response to treatment could reflect autoimmunity in remission. [ABSTRACT FROM AUTHOR]

The article presents a study which analyzes that CD18 (ITGB2) gene expression in chronic lymphocytic leukaemia (CLL) is regulated by DNA methylation-dependent and -independent mechanisms. The study also analyzed correlation between active NFKB1 binding site levels and CD18 expression in CLL cells as ITGB2 promoter contains NFKB1 binding site.

Purpose Leukocyte adhesion deficiency type-I (LAD-I) is caused by mutations in the ITGB2 gene, encoding the β 2 -subunit of β 2 -integrin (CD18) which leads to markedly reduced expression of CD18 on leukocytes resulting into recurrent life threatening infections. Here we aim to identify the molecular defects underlying LAD-I in Indian patients and correlate with the clinical presentation. Methods Blood was collected from 30 patients and their parents for absolute neutrophil count, expression of CD18 and CD11 by flow cytometry and DNA extraction. PCR and DNA sequencing of the ITGB2 gene was done for mutation characterization. Results Phenotypically, 22 patients were LAD-I 0 , 1 was LAD-I − and 7 were LAD-I + showing no expression and reduced expression of CD18 respectively. Nine novel mutations in 15 patients and 11 known mutations in 16 patients were detected. Prenatal diagnosis was performed for 5 families. Conclusion In this study 30 patients were phenotypically and genotypically evaluated for a less known disease LAD-I. Unavailability of curative options to majority of the patients and high cost of supportive care emphasize the need to increase awareness about a suspicious case so that timely management can be given to the patient and prenatal diagnosis can be offered to their families. [ABSTRACT FROM AUTHOR]

Leukocyte Adhesion Deficiency I (LAD-I) is a primary immunodeficiency caused by single gene mutations in the CD18 subunit of β2 integrins which result in defective transmigration of neutrophils into the tissues. Affected patients suffer from recurrent life threatening infections and severe oral disease (periodontitis). Microbial communities in the local environment (subgingival plaque) are thought to be the triggers for inflammatory periodontitis, yet little is known regarding the microbial communities associated with LAD-I periodontitis. Here we present the first comprehensive characterization of the subgingival communities in LAD-I, using a 16S rRNA gene-based microarray, and investigate the relationship of this tooth adherent microbiome to the local immunopathology of periodontitis. We show that the LAD subgingival microbiome is distinct from that of health and Localized Aggressive Periodontitits. Select periodontitis-associated species in the LAD microbiome included Parvimonas micra, Porphyromonas endodontalis, Eubacterium brachy and Treponema species. Pseudomonas aeruginosa, a bacterium not typically found in subgingival plaque is detected in LAD-I. We suggest that microbial products from LAD-associated communities may have a role in stimulating the local inflammatory response. We demonstrate that bacterial LPS translocates into the lesions of LAD-periodontitis potentially triggering immunopathology. We also show in in vitro assays with human macrophages and in vivo in animal models that microbial products from LAD-associated subgingival plaque trigger IL-23-related immune responses, which have been shown to dominate in patient lesions. In conclusion, our current study characterizes the subgingival microbial communities in LAD-periodontitis and supports their role as triggers of disease pathogenesis. [ABSTRACT FROM AUTHOR]

Objectives: Adrenergic modulation of immunity has been extensively characterized, however, few information exist regarding polymorphonuclear leukocytes (PMN), despite their key role in immunity and inflammation. We investigated the effect of adrenergic agents on human PMN migration, CD11b and CD18 expression, reactive oxygen species (ROS) and interleukin (IL)-8 production, and on adrenoceptor (AR) expression. Methods: Migration was measured by the Boyden chamber assay, CD11b/CD18 expression was assessed by flow cytometry, intracellular ROS were detected by spectrofluorimetry, and IL-8 was quantitated by standard ELISA assay. AR mRNA levels were measured by real-time PCR and PMN morphology was studied by scanning electron microscopy. Results: Adrenaline(A), noradrenaline and the β-AR agonist isoprenaline reduced N-formyl-Met-Leu-Phe (fMLP)-induced migration, CD11b/CD18 expression, and ROS production, without affecting IL-8. The effect of A on CD11b was antagonized by yohimbine and propranolol, and increased by prazosin. The effect on ROS production was completely abolished by propranolol. PMN expressed α-, α-, α-, α-, α-, β-, β-, and β-AR mRNA. A prevented fMLP-induced morphological changes of PMN. Conclusions: Adrenergic agents reduced PMN responses mainly through β-AR, although α-AR may contribute at least to CD11b expression. AR-operated pathways in PMN should be investigated in disease conditions and in the response to therapeutic agents. [ABSTRACT FROM AUTHOR]

Objective To investigate the effects of 20 methanolic extracts from Malaysian selected plants on CD18/11a expression and phagocytosis activity of leukocytes using flow cytometry analysis. Methods The effects of methanolic extracts on CD18/11a expression and phagocytosis of leukocytes were measured by labelling the cells with CD18-fluorescein isothiocyanate and ingestion labelled with Escherichia coli -fluorescein isothiocyanate and then analyzed using flow cytometer. Results About 12 out of 20 methanolic extracts of selected Malaysian medicinal plants significantly ( P ≤0.05) inhibited the CD18/11a expression of leukocytes at both concentrations of 6.25 μg/mL and 100 μg/mL in dose dependent manner. The most active inhibitory was shown in Citrus aurantifolia (Christm.) Swingle and Alpinia galangal (L.) Willd. at dosage 100 μg/mL. Moreover, the Orthosiphon aristatus (Blume) Miq ( O. aristatus ). showed the highest stimulatory activity at the concentration of 100 μg/mL. Other than that, four plant extracts significantly ( P ≤0.05) rose the phagocytosis activities of leukocytes in dose dependent manner. However, Annona muricata L. and O. aristatus showed the highest stimulated activities at the 100 μg/mL concentration. Conclusions The results suggest that methanolic extracts of Citrus aurantifolia, Alpinia galangal, O. aristatus and Annona muricata are able to modulate innate immune system and can potentially be recognized as therapeutic agents for modulating immune system. [ABSTRACT FROM AUTHOR]

Leukocyte adhesion deficiency type 1 (LAD 1 — CD18 deficiency) is a rare disease characterized by disturbance of phagocyte function associated with less severe cellular and humoral dysfunction. The main features are bacterial and fungal infections predominantly in the skin and mucosal surfaces, impaired wound healing and delayed umbilical cord separation. The infections are indolent, necrotic and recurrent. In contrast to the striking difficulties in defense against bacterial and fungal microorganisms, LAD 1 patients do not exhibit susceptibility to viral infections and neoplasias. The severity of clinical manifestations is directly related to the degree of CD18 deficiency. Here, a 20 year-old female presenting a partial CD18 deficiency that developed a megakaryocytic (M7) acute myeloid leukemia is described for the first time. The clinical features of the patient included relapsing oral thrush due to Candida, cutaneous infections and upper and lower respiratory tract infections, followed by a locally severe necrotic genital herpetic lesion. The patient's clinical features improved for a period of approximately two years, followed by severe bacterial infections. At that time, the investigation showed a megakaryocytic acute myeloid leukemia, treated with MEC without clinical improvement. The highly aggressive evolution of the leukemia in this patient suggests that adhesion molecules could be involved in the protection against the spread of neoplastic cells. [ABSTRACT FROM AUTHOR]

Diffuse pulmonary hemorrhage (DPH) is an uncommon but critical complication of systemic lupus erythematosus. Peritoneal administration of 2,6,10,14-tetramethylpentadecane (pristane) can recapitulate a lupus-like syndrome in mice, which can develop into DPH within a few weeks, especially in C57BL/6 mice. Mac-1 (CD11b/CD18), a leukocyte adhesion molecule, is known to play a role in inflammation by regulating migration of leukocytes into injured tissue. In this study, we aimed to clarify the role of Mac-1 in pristane-induced DPH, using Mac-1-/- and wild-type (WT) mice on a C57BL/6 background. After pristane injection, Mac-1-/- mice showed reduced prevalence of DPH and attenuated peritonitis compared with WT mice. Analysis of the peritoneal lavage on days 5 and 10 after pristane treatment revealed increased numbers of eosinophils and alternatively activated macrophages, but decreased numbers of neutrophils and classically activated macrophages in Mac-1-/- mice compared with WT. Enhanced production of IL-4 and IL-13, both key mediators of macrophage polarization toward the mannose receptor+ (MMR+) phenotype, was observed in the peritoneal cavity of Mac-1-/- mice. Depletion of neutrophils and eosinophils or adoptive transfer of classically activated macrophages resulted in the exacerbation of pristane-mediated DPH in both WT and Mac-1-/- mice. Moreover, peritoneal transfer of F4/80highMMR+ alternatively activated macrophages successfully reduced the prevalence of DPH in WT mice. Collectively, Mac-1 promoted acute inflammatory responses in the peritoneal cavity and the lungs by downregulating granulocyte migration and subsequent phenotypic conversion of macrophages in a pristane-induced systemic lupus erythematosus model. [ABSTRACT FROM AUTHOR]

Inflammation of blood vessels is a characteristic feature of Kawasaki disease. Neutrophils play a key role in the inflammatory responses where movement of neutrophils toward the site of inflammation depends on CD11b/CD18 expression as adhesion molecules on these cells. The purpose of this study was to investigate CD11b/CD18 expression in patients with Kawasaki disease upon diagnosis and after treatment. The study included 20 children with Kawasaki disease aged from 3 months to 8 years. Mean fluorescence intensity of CD11b levels on diagnosis and at 1-2 and 6 weeks after intravenous immunoglobulin (IVIG) therapy was measured in these patients. Level of CD11b was measured in age-matched healthy children and febrile children (each 21) as negative and positive controls, respectively. Mean fluorescence intensity of CD11b in Kawasaki patients was lower than that of the control groups before and after 1-2 weeks of IVIG therapy. There were no significant differences in CD11b in Kawasaki patients either with aneurysm or without aneurysm. The CD11b levels at the diagnosis time and after treatment with IVIG in our patients with Kawasaki were lower than the control groups. [ABSTRACT FROM AUTHOR]

Shear stress-induced cleavage of cell surface CD18 integrins is reported to be part of an anti-inflammatory control mechanism that minimizes neutrophil activity in the blood under physiologic conditions. The cysteine protease, cathepsin B (catB), has been implicated in this mechanoregulatory mechanism, but its molecular dynamics remain to be elucidated. Moreover, attempts to do so using molecular approaches are hindered by the limited ex vivo life span of primary neutrophils. As an alternative, we explored the potential use of HL60-derived neutrophilic cells as a transfectable culture model that exhibits a shear-induced CD18 cleavage response comparable to primary neutrophils. HL60 cells were differentiated into neutrophil-like cells (dHL60-NCs) and exposed to laminar shear stress ( $$5\, \hbox {dynes}/\hbox {cm}^{2}$$ for 10 min). Based on cytometric analyses, sheared cells cleaved CD18 and CD11a, but not CD11b, integrins. Treatment of cells with E64 or doxycycline prior to and during shear exposure inhibited CD18, but only attenuated CD11a, cleavage. Neither aprotinin nor pepstatin affected shear-induced CD18 or CD11a cleavage. Notably, dHL60-NCs expressed minimal catB. Thus, multiple cysteine proteases in addition to catB may cleave CD18 on sheared leukocytes. In fact, our findings indicate that multiple non-cysteine proteases also participate in the shear-related cleavage of CD11/CD18 heterodimers. Finally, shear-induced cleavage of CD18 and CD11a by dHL60-NCs was inhibited by fMLP concentrations of at least $$1\,\upmu \hbox {M}$$ . Collectively, our findings indicate that shear-induced CD11/CD18 cleavage is phenotypic of neutrophilic cells, including those derived from HL60 cells. Moreover, our results verify shear stress as a key anti-inflammatory stimulus for neutrophils under physiologic conditions. [ABSTRACT FROM AUTHOR]

Highlights: [•] Oleacein is a phenolic compound of olive oil. [•] Oleacein inhibited neutral endopeptidase in human neutrophils. [•] Oleacein suppressed CD11b/CD18 expression and elastase release in PMNs. [•] Oleacein effect was stronger than the effect of phosphoramidon. [•] The combination with ANP or BNP caused a reduction of elastase and MMP-9 release. [ABSTRACT FROM AUTHOR]

Background: Recent observational clinical and ex-vivo studies suggest that inflammation and in particular leukocyte activation predisposes to atrial fibrillation (AF). However, whether local binding and extravasation of leukocytes into atrial myocardium is an essential prerequisite for the initiation and propagation of AF remains elusive. Here we investigated the role of atrial CD11b/CD18 mediated infiltration of polymorphonuclear neutrophils (PMN) for the susceptibility to AF. Methods and Results: C57bl/6J wildtype (WT) and CD11b/CD18 knock-out (CD11b−/−) mice were treated for 14 days with subcutaneous infusion of angiotensin II (Ang II), a known stimulus for PMN activation. Atria of Ang II-treated WT mice were characterized by increased PMN infiltration assessed in immunohistochemically stained sections. In contrast, atrial sections of CD11b−/− mice lacked a significant increase in PMN infiltration upon Ang II infusion. PMN infiltration was accompanied by profoundly enhanced atrial fibrosis in Ang II treated WT as compared to CD11b−/− mice. Upon in-vivo electrophysiological investigation, Ang II treatment significantly elevated the susceptibility for AF in WT mice if compared to vehicle treated animals given an increased number and increased duration of AF episodes. In contrast, animals deficient of CD11b/CD18 were entirely protected from AF induction. Likewise, epicardial activation mapping revealed decreased electrical conduction velocity in atria of Ang II treated WT mice, which was preserved in CD11b−/− mice. In addition, atrial PMN infiltration was enhanced in atrial appendage sections of patients with persistent AF as compared to patients without AF. Conclusions: The current data critically link CD11b-integrin mediated atrial PMN infiltration to the formation of fibrosis, which promotes the initiation and propagation of AF. These findings not only reveal a mechanistic role of leukocytes in AF but also point towards a potential novel avenue of treatment in AF. [ABSTRACT FROM AUTHOR]

Tuberculosis ( TB) remains a major global health problem accounting for millions of deaths annually. Approximately one-third of the world's population is infected with the causative agent Mycobacterium tuberculosis. The onset of an adaptive immune response to M. tuberculosis is delayed compared with other microbial infections. This delay permits bacterial growth and dissemination. The precise mechanism(s) responsible for this delay have remained obscure. T-cell activation is preceded by dendritic cell ( DC) migration from infected lungs to local lymph nodes and synapsis with T cells. We hypothesized that M. tuberculosis may impede the ability of DCs to reach lymph nodes and initiate an adaptive immune response. We used primary human DCs to determine the effect of M. tuberculosis on expression of heterodimeric integrins involved in cellular adhesion and migration. We also evaluated the ability of infected DCs to adhere to and migrate through lung endothelial cells, which is necessary to reach lymph nodes. We show by flow cytometry and confocal microscopy that M. tuberculosis-infected DCs exhibit a significant reduction in surface expression of the β2 ( CD18) integrin. Distribution of integrin β2 is also markedly altered in M. tuberculosis-infected DCs. A corresponding reduction in the αL ( CD11a) and αM ( CD11b) subunits that associate with integrin β2 was also observed. Consistent with reduced integrin surface expression, we show a significant reduction in adherence to lung endothelial cell monolayers and migration towards lymphatic chemokines when DCs are infected with M. tuberculosis. These findings suggest that M. tuberculosis modulates DC adhesion and migration to increase the time required to initiate an adaptive immune response. [ABSTRACT FROM AUTHOR]

Abstract: Neutrophils are first responders to injury in inflammatory diseases of the central nervous system (CNS) such as ischemic stroke, trauma and intracerebral hemorrhage. Studies carried out in the last three decades showed that neutrophils have mixed effects in animal models of stroke. Some studies correlated the presence of neutrophils to injury. When neutrophil infiltration was reduced by targeting CD18 or intercellular adhesion molecule-1 (ICAM-1) this generated improved outcomes. However other studies showed that when neutrophil infiltration was stimulated prior to stroke, this reduced the burden of disease. Clinical trials did not show a benefit in stroke patients from neutrophil blockade. Neutrophils may be subject to a threshold effect. When they reach a critical ratio relative to the volume of injury in the CNS, they adopt an anti-inflammatory phenotype that is able to reduce disease. When neutrophil infiltration was stimulated by injecting a stroke site in the rat with the chemokine CXCL1, this resulted in reductions in vascular permeability. Similar reductions in permeability were modeled in tissue culture models, in which neutrophils were applied to monolayers of brain endothelial cells. Neutrophils blocked the permeability increases associated with oxygen-glucose deprivation in human brain endothelial monolayers. The evidence suggests that neutrophils might adopt a pro-inflammatory N1 phenotype or an anti-inflammatory N2 phenotype in the CNS depending on environmental cues. The N2 phenotype may be adopted when neutrophil numbers exceed a critical threshold. This suggests that strategies that promote neutrophil infiltration into stroke, and other CNS inflammatory diseases, could result in improved outcomes. [Copyright &y& Elsevier]

Mechanisms by which tumor cells metastasize to distant organs still remain enigmatic. Immune cells have been assumed to be the root of metastasis by their fusing with tumor cells. This fusion theory, although interpreting tumor metastasis analogically and intriguingly, is arguable to date. We show in this study an alternative explanation by immune cell-derived microparticles (MPs). Upon stimulation by PMA or tumor cell-derived supernatants, immune cells released membrane-based MPs, which were taken up by H22 tumor cells, leading to tumor cell migration in vitro and metastasis in vivo. The underlying molecular basis was involved in integrin αMβ2 (CD11b/CD18), which could be effectively relayed from stimulated innate immune cells to MPs, then to tumor cells. Blocking either CD11b or CD18 led to significant decreases in MP-mediated tumor cell metastasis. This MP-mediated transfer of immune phenotype to tumor cells might also occur in vivo. These findings suggest that tumor cells may usurp innate immune cell phenotypes via MP pathway for their metastasis, providing new insight into tumor metastatic mechanism. [ABSTRACT FROM AUTHOR]

Abstract: This study was undertaken to evaluate the effects of thin film hyaluronic acid and dextran surface coatings to blunt cellular activation in a laboratory model of extracorporeal blood circulation. The inner lumen surface of polyurethane (PU) and poly(vinyl) chloride (PVC) tubing was grafted with hyaluronic acid and dextran. Surfaces were characterized for the presence of the grafted layer using ellipsometry, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Persistence of the surface layer was maintained for up to 5 days of continuous exposure to shear flow using a Chandler loop apparatus. The Chandler loop method was used to study human whole blood activation activity. Whole blood aggregometry and flow cytometry measures of CD18, CD62L, CD62P, Annexin V and myeloperoxidase performed on blood samples exposed to the tubing for up to three hours were complemented by scanning electron microscopy (SEM) analysis of adherent cells and state of activation. In these studies commercial hospital products and uncoated PVC and PU tubes were used as controls. We found that hyaluranized PU and PVC conferred the greatest resistance to blood activation and that dextranization of the PU and PU tubing also provided significant diminution of the bioresponses measured. Based on our findings, we suggest that surface coating with hyaluronic acid or dextran acts as a potent shield from blood cellular activation during forms of extracorporeal circulation. [Copyright &y& Elsevier]

Objective--To characterize systemic immune responses in Cytauxzoon felis-infected cats. Sample--Blood and lung samples obtained from 27 cats. Procedures--Cats were allocated into 4 groups: cats that died of cytauxzoonosis, acutely ill C felis-infected cats, healthy survivors of C felis infection, and healthy uninfected cats. Serum concentrations of tumor necrosis factor-α and interleukin-1 β were measured and serum proteins characterized. Blood smears were stained immunocytochemically and used to assess immunoglobulin deposition. Immunohistochemical expression of CD18 and tumor necrosis factor-α were compared in lung tissues obtained from cats that died and healthy uninfected cats. A real-time reverse-transcription PCR assay for CD18 expression was performed on selected blood samples from all groups. Results--Concentrations of both cytokines were greater and serum albumin concentrations were significantly lower in cats that died of cytauxzoonosis, compared with results for all other groups. Erythrocytes from acutely ill cats and survivors of C felis infection had staining for plasmalemmal IgM, whereas erythrocytes from the other groups did not. Increased staining of C fells-infected monocytes and interstitial neutrophils for CD18 was detected. The real-time reverse-transcription PCR assay confirmed a relative increase in CD18 expression in cats that died of cytauxzoonosis and acutely ill cats, compared with expression in other groups. Immunostaining for TNF-α in lung samples confirmed a local proinfiammatory response. Conclusions and Clinical Relevance--Results indicated immunopathologic responses were greater in cats that died of C felis infection than in cats that survived C felis infection. [ABSTRACT FROM AUTHOR]

Defective development and function of CD4+CD25high+Foxp3+ regulatory T cells (Tregs) contribute to the pathogenesis of psoriasis and other autoimmune diseases. Little is known about the influence of adhesions molecules on the differentiation of Foxp3+ Tregs into proinflammatory Th17 cells occurring in lesional skin and blood of psoriasis patients. In the CD18hypo PL/J mouse model of psoriasis, reduced expression of CD18/β2 integrin to 2-16% of wild-type levels is associated with progressive loss of Tregs, impaired cell-cell contact between Tregs and dendritic cells (DCs), as well as Treg dysfunction as reported earlier. In the present investigation, Tregs derived from CD18hypo PL/J mice were analyzed for their propensity to differentiate into IL-17-producing Th17 cells in vivo and in in vitro Treg-DC cocultures. Adoptively transferred CD18hypo PL/J Tregs were more inclined toward conversion into IL-17-producing Th17 cells in vivo in an inflammatory as well as noninflammatory environment compared with CD18wt PL/J Tregs. Addition of neutralizing Ab against CD18 to Treg-DC cocultures in vitro promoted conversion of CD18wt PL/J Tregs to Th17 cells in a dose-dependent manner similar to conversion rates of CD18hypo PL/J Tregs. Reduced thymic output of naturally occurring Tregs and peripheral conversion of Tregs into Th17 cells therefore both contribute to the loss of Tregs and the psoriasiform dermatitis observed in CD18hypo PL/J mice. Our data overall indicate that CD18 expression levels impact Treg development as well as Treg plasticity and that differentiation of Tregs into IL-17-producing Th17 cells is distinctly facilitated by a subtotal deficiency of CD18. [ABSTRACT FROM AUTHOR]

Abstract: Previous studies have reported that C-reactive protein (CRP) interacting with low-density lipoproteins (LDL) affects macrophage activation and LDL uptake. However, the physiological relevance of CRP-LDL interaction with circulating monocytes remains elusive. Moreover, recent studies have shown that CRP exists in two isoforms with partly opposing characteristics pentameric (pCRP) and monomeric CRP (mCRP). Here we investigated the effects of CRP interacting with minimally modified low-density lipoprotein (mmLDL) interaction in regard to events involved in formation of atherosclerotic plaque. We analyzed the effect of mmLDL on human monocytes and found a substantial increase in monocyte activation as evaluated by CD11b/CD18 expression and increased monocyte adhesion under static and under shear flow conditions to human endothelial cells. Monocyte adhesion and activation was attenuated by pCRP via the prevention of mmLDL binding to monocytes. These anti-inflammatory properties of pCRP were lost when it dissociates to the monomeric form. Our results elucidate the physiological relevance of the CRP-mmLDL interaction and furthermore confirm the importance of the previously described pCRP dissociation to mCRP as a localized inflammatory “activation” mechanism. [Copyright &y& Elsevier]

CD18 expressing phagocytes associated with the gastro-intestinal (GI) epithelium can shuttle Salmonella directly into the bloodstream within a few minutes following microbial ingestion. We have previously demonstrated that Salmonella controls the CD18 pathway to deeper tissue, manipulating the migratory properties of infected cells as an unappreciated component of its pathogenesis. We have observed that one type III effector, SrfH (also called SseI) that Salmonella secretes into infected phagocytes manipulates the host protein TRIP6 to stimulate their migration. Paradoxically, SrfH was shown in another study to subvert a different host protein, IQGAP1, in a manner that inhibits the productive motility of such cells, perhaps to avoid interactions with T cells. Here, we resolve the discrepancy. We report that one naturally occurring allele of srfH promotes the migration of infected phagocytes into the bloodstream, while another naturally occurring allele that differs by only a single nucleotide polymorphism (SNP) does not. This SNP determines if the protein contains an aspartic acid or a glycine residue at position 103 and may determine if SrfH binds TRIP6. SrfH Gly103 is a rare allele, but is present in the highly invasive strain Salmonella enterica serovar Typhimurium UK-1 (stands for universal killer). It is also present in the genome of the only sequenced strain belonging to the emerging pandemic Salmonella enterica serovar 4, [5],12,i:-, which is frequently associated with septicemia. Finally, we present evidence that suggests that Gifsy-2, the bacteriophage upon which srfH resides, is present in a clinical isolate of the human-specific pathogen, Salmonella enterica serovar Typhi. These observations may have interesting implications for our understanding of Salmonella pathogenesis. [ABSTRACT FROM AUTHOR]

Interferon-γ (IFNγ)-mediated signal transduction via upregulation of signal transducer and activator of transcription (STAT) 1 leads to the expression of the mucin (MUC) 4 gene in pancreatic cancer cells. Upregulation of STAT1 may also implicate STAT1 tyrosine- or serine-phosphorylation. Experimental data indicate that reaction steps involved in IFNγ-induced serine-phosphorylation of STAT1 vary between cell types in contrast to conserved IFNγ-induced tyrosine-phosphorylation of STAT1. The above observations raise the following two questions: (i) How does IFNγ stimulation regulates serine-phosphorylation of STAT1 in the pancreatic cancer cell line CD18/HPAF? (ii) Which type of STAT1 acts as a transcription factor of MUC4? Our objective is to address these two questions by data-driven mathematical modelling. Simulation results of the parameterised ordinary differential equation models show that serine-phosphorylation of unphosphorylated STAT1 occurs in the cytoplasm. In contrast, serine-phosphorylation of tyrosine-phosphorylated STAT1 can take place in the cytoplasm or in the nucleus. In addition, our results propose that unphosphorylated or serine-phosphorylated STAT1 can act as transcription factors of MUC4, either alone by progressive binding to different sites in the promoter or both together. [ABSTRACT FROM AUTHOR]

Lingual lesions are relatively uncommon in dogs and are mostly represented by neoplasms and glossitis secondary to trauma or infections. Reactive histiocytosis is an uncommon, poorly understood, reactive disorder characterized by proliferation of activated, interstitial, dendritic, antigen-presenting cells associated with lymphocytes and neutrophils with a specific angiocentric orientation and occasional angioinvasion and angio-destruction. Clinically, the disease has a waxing and waning behavior with possible response to treatment and regression, on agression to multiple lesions and internal organ involvement. This case report describes an unusual sublingual presentation of reactive histiocytosis in a Miniature Pinscher dog. The diagnosis was obtained by clinical and histopathological exclusion of other causes, detection of the characteristic microscopic growth pattern, and by immunocytochemistry. Histiocytic cells were vimentin, CD18, CD11c, and CD1cpositive consistent with a dendritic cell origin. Anti-BCG stain (Bacillus Calmette and Guerin) was negative for etiological agents. The dog was treated with oral administration of tetracycline and niacinamide during an 8-month period. There was no indication of recurrence of the sublingual mass 2-years following treatment. [ABSTRACT FROM AUTHOR]

The article presents a study which evaluates the cell-surface expression of CD180 in patients with B-cell lymphoproliferative disease (B-LPD) using cytometry. Findings reveal that the B cells of B-LPD patients showed weaker expression of CD180 compared to healthy subjects. It concludes the difference of CD180 expression in malignant B cells.

The article presents a study regarding the function of CD2 and CD18 receptors in antibody-dependent cellular cytotoxicity using the preincubation of monoclonal antibodies with the natural killer clone EB4.19. The results indicate that adhesion between cells mediated by CD2 and CD18 is a prerequisite for subsequent activation of the lytic program through the CD16 receptor.

Background: Neutrophil recruitment during acute inflammation critically depends on the spatial and temporal regulation of β2 integrins (CD11/CD18). This regulation occurs by inside‐out and outside‐in signalling via interaction of cytoplasmic proteins with the intracellular domains of the integrin α‐ and β‐subunits. The underlying molecular mechanisms regulating β2 integrins in neutrophils are still incompletely understood. Aim: This review provides a comprehensive overview of our current knowledge on proteins interacting with the cytoplasmic tail of CD18, the conserved β‐subunit of β2 integrins, their regulation and their functional importance for neutrophil trafficking during acute inflammation. Results: A total of 22 proteins including Talin, Kindlin 3 and Coronin 1A have been reported to interact with the CD18 cytoplasmic tail. Here, proteins binding to the cytoplasmic domain of CD18 in experiments using purified, recombinant proteins or peptides in, for example, pull‐down assays, are defined as direct interactors. Proteins that have been shown to interact with the cytoplasmic domain of CD18 using whole cell lysates in, for example, pull‐down experiments are claimed as interacting proteins without evidence for direct interaction. In summary, β2 integrin activation and signalling depend on a specific subset of proteins interacting with CD18 and their precise regulation. If disturbed, profound defects of neutrophil recruitment and activation become evident compromising the innate immune response. Conclusions: The knowledge of proteins interacting with β2 integrins and their regulation during neutrophil trafficking does not only improve our basic understanding of innate immunity but may pave the way to novel therapeutic strategies in the treatment of inflammatory diseases. [ABSTRACT FROM AUTHOR]