The 'D-M-C' strategy for conventional ameloblastoma of the mandible: a retrospective study

The purpose of this multicentre study was to evaluate the efficacy of the 'dredging-marsupialization-curettage' (D-M-C) strategy in the treatment of conventional intraosseous ameloblastoma of the mandible. A total of 31 patients from three institutions, who had a pathological diagnosis of conventional ameloblastoma of the mandible, were treated with the D-M-C strategy. The surgical protocol comprised a dredging and marsupialization (D-M) step, with additional D-M steps as required. The patients then underwent curettage (C) once an obvious effect of the D-M step had been achieved during follow-up. Eight patients were followed up for ≥36 months but <60 months, while 23 were followed up for ≥60 months. Nineteen of the 23 patients followed up for ≥60 months were disease-free at the last follow-up, with no evidence of recurrence. The D-M step is effective for reducing the tumour size and preserving vital structures. The D-M-C surgical strategy may be a feasible treatment option for conventional ameloblastoma of the mandible.

[Value of purple sign for predicting rebleeding events in cirrhotic patients following endoscopic selective varices devascularization]

OBJECTIVE

To assess the value of the purple sign for predicting long-term rebleeding events in cirrhotic patients following endoscopic selective varices devascularization.

METHODS

We retrospectively analyzed the clinical data of 97 patients with liver cirrhosis, who had a history of gastroesophageal variceal bleeding and underwent endoscopic selective varices devascularization. Thirty-two of the patients showed purple sign after endoscopic treatment. We used propensity score matching (PSM) to minimize the selection bias of the patients (purple sign vs no purple sign) and reduce the intergroup differences of clinical characteristics. The primary outcome measure of this study was cumulative rebleeding events after endoscopic selective varices devascularization.

RESULTS

The 1-year rebleeding rate (27.0% vs 36.7%) or 6-month rebleeding rate (10.9% vs 26.9%) following endoscopic treatment was not significantly different between the purple sign group and no purple sign group before PSM (P=0.2385). But after PSM, the 1-year rebleeding rate (28.2% vs 56.4%) and 6-month rebleeding rate (5.0% vs 37.0%) were significantly lower in the purple sign group than in the no purple sign group (P=0.0304).

CONCLUSIONS

The presence of purple sign indicates a lower risk of rebleeding after endoscopic treatment of cirrhotic gastroesophageal varices and a potentially favorable treatment response after endoscopic therapy, thus providing a clinical indicator for stratification of the patients for sequential endoscopic sessions.

In situ small-angle X-ray scattering studies during the formation of polymer/silica nanocomposite particles in aqueous solution

This study is focused on the formation of polymer/silica nanocomposite particles prepared by the surfactant-free aqueous emulsion polymerization of 2,2,2-trifluoroethyl methacrylate (TFEMA) in the presence of 19 nm glycerol-functionalized aqueous silica nanoparticles using a cationic azo initiator at 60 °C. The TFEMA polymerization kinetics are monitored using 1H NMR spectroscopy, while postmortem TEM analysis confirms that the final nanocomposite particles possess a well-defined core-shell morphology. Time-resolved small-angle X-ray scattering (SAXS) is used in conjunction with a stirrable reaction cell to monitor the evolution of the nanocomposite particle diameter, mean silica shell thickness, mean number of silica nanoparticles within the shell, silica aggregation efficiency and packing density during the TFEMA polymerization. Nucleation occurs after 10-15 min and the nascent particles quickly become swollen with TFEMA monomer, which leads to a relatively fast rate of polymerization. Additional surface area is created as these initial particles grow and anionic silica nanoparticles adsorb at the particle surface to maintain a relatively high surface coverage and hence ensure colloidal stability. At high TFEMA conversion, a contiguous silica shell is formed and essentially no further adsorption of silica nanoparticles occurs. A population balance model is introduced into the SAXS model to account for the gradual incorporation of the silica nanoparticles within the nanocomposite particles. The final PTFEMA/silica nanocomposite particles are obtained at 96% TFEMA conversion after 140 min, have a volume-average diameter of 216 ± 9 nm and contain approximately 274 silica nanoparticles within their outer shells; a silica aggregation efficiency of 75% can be achieved for such formulations.

Characterization of bacteriophage HN48 and its protective effects in Nile tilapia Oreochromis niloticus against Streptococcus agalactiae infections

Streptococcus agalactiae is a causative agent responsible for massive mortalities of tilapia that has led to catastrophic losses to tilapia culture globally. Bacteriophages represent a new class of antimicrobials against bacteria. In this study, we characterized the bacteriophage HN48, which formed small and round-transparent plaques on a double-layer plate. With a hexagonal head and a long tail, this phage may belong to the Caudovirales according to the International Committee on Taxonomy of Viruses. HN48 was found to have a relatively wide and highly specific host range, to be sensitive to high temperature (60-80°C) and low pH (3-5), and to be relatively stable at alkaline pH (8-10). Intraperitoneal injection with HN48 had no adverse effects on tilapia and effectively inactivated the bacteria in the kidney. Fish that received phage therapy had 60% ± 3.3% survival rates and a delayed mean death time of about 3 days when compared to the control group. To the best of knowledge, this is the first study of tilapia streptococcal phage. Overall, the results indicated that phage HN48 could prevent tilapia from experimental S. agalactiae infection, suggesting it has the potential to control this disease.

Dual Ion Species Plasma Expansion from Isotopically Layered Cryogenic Targets

A dual ion species plasma expansion scheme from a novel target structure is introduced, in which a nanometer-thick layer of pure deuterium exists as a buffer species at the target-vacuum interface of a hydrogen plasma. Modeling shows that by controlling the deuterium layer thickness, a composite H^{+}/D^{+} ion beam can be produced by target normal sheath acceleration (TNSA), with an adjustable ratio of ion densities, as high energy proton acceleration is suppressed by the acceleration of a spectrally peaked deuteron beam. Particle in cell modeling shows that a (4.3±0.7)  MeV per nucleon deuteron beam is accelerated, in a directional cone of half angle 9°. Experimentally, this was investigated using state of the art cryogenic targetry and a spectrally peaked deuteron beam of (3.4±0.7)  MeV per nucleon was measured in a cone of half angle 7°-9°, while maintaining a significant TNSA proton component.

wblA, a pleiotropic regulatory gene modulating morphogenesis and daptomycin production in Streptomyces roseosporus

AIMS

The wblA gene, encoding a homologue of the WhiB family protein, was identified in the sequenced genome of daptomycin producer Streptomyces roseosporus. To explore the function of wblA, we construct wblA disruption strains, complemented strains and overexpression strains to test whether it can affect the production of secondary metabolites and morphogenesis.

METHODS AND RESULTS

We constructed disruption strains by homologous recombination in S. roseosporus. The disruption mutant of wblA could block aerial mycelium sporulation and enhance the production of daptomycin by 51%. In contrast, overexpression of wblA resulted in significantly decreased the yield of daptomycin. In agreement with it, the transcription of key daptomycin regulatory genes atrA, dptR2 and dptR3 and structural gene dptE remarkably increased in the wblA disruption mutant.

CONCLUSIONS

wblA plays a key role in control of daptomycin biosynthesis and is essential for sporulation. The disruption of wblA could accumulate the transcription level of some key genes involving in daptomycin biosynthesis.

SIGNIFICANCE AND IMPACT OF THE STUDY

Daptomycin is an important antibiotic with potent activity against a variety of Gram-positive pathogens. This study demonstrates that valuable improvement in the yield of daptomycin can be achieved through modulating the expression of wblA transcription regulator.

Enteral versus parenteral nutrition in critically ill patients with severe pancreatitis: a meta-analysis

Whether enteral nutrition (EN) is superior to parenteral nutrition (PN) in critically ill patients with severe acute pancreatitis remains unknown. The objective of this meta-analysis was to assess the effects of EN versus PN on clinical outcomes in a subgroup of pancreatitis patients. Relevant randomized controlled trials (RCTs) were searched in Scopus, PubMed and Web of Science from inception to August 2016. Ultimately, five RCTs including 348 patients were enrolled in this analysis. Compared with PN, EN was associated with a significant reduction in overall mortality (risk ratio (RR)=0.36, 95% confidence interval (CI) 0.20-0.65, P=0.001) and the rate of multiple organ failure (RR=0.39, 95% CI 0.21-0.73, P=0.003). EN should be recommended as the preferred route of nutrition for critically ill patients with severe acute pancreatitis.

Design and Synthesis of Nanofibers of Self-assembled de novo Glycoconjugates towards Mucosal Lining Restoration and Anti-Inflammatory Drug Delivery

The medical practice for IBD is solely based on anti-inflammatory drugs, but the outcome is far from ideal. Our long-term research goal is to seek a better clinical outcome by combining the anti-inflammatory therapy with physical mucus layer restoration. As the first step towards that objective, we choose to develop self-assembled hydrogels of de novo glycoconjugates that consist of anti-inflammatory drugs and glycopeptides. By covalently linking peptides (e.g., nap-phe-phe-lys), saccharides (e.g., glucosamine), and an anti-inflammatory drug (i.e., olsalazine), we have demonstrated that the obtained molecules self-assemble in water to form hydrogels composed of 3D networks of the nanofibers under acidic conditions. We also confirmed that the resulting glycoconjugates are cell compatible. However, the preliminary assessment of the efficacy of the hydrogels on the murine model is inconclusive, which warrants further investigation and molecular engineering.

Influence of pelvic postural angle change on acetabulum implantation in total hip arthroplasty

The current study investigated the relationship between the implantation angle of the acetabular component and the change in the pelvic postural angle during hip arthroplasty surgery. One pelvis with a left lower limb prosthesis was used. Total hip arthroplasty on the left pelvis was simulated with the help of a computer-assisted navigation system. The pelvis revolved around the horizontal, longitudinal and sagittal axes at different angles, and the anteversion and abduction of the acetabular component were measured. The changing angle of the pelvis rotating around the horizontal and longitudinal axes greatly influenced acetabular component anteversion. The changing angle of the pelvis rotating around the sagittal axis had a relatively great influence on the acetabular component abduction angle. The change in the postural angle of the pelvis had a great influence on the installation angle of the acetabular component. It is important to standardize posture prior to the operation.

Responses to Microbial Challenges by SLAMF Receptors

The SLAMF family (SLAMF) of cell surface glycoproteins is comprised of nine glycoproteins and while SLAMF1, 3, 5, 6, 7, 8, and 9 are self-ligand receptors, SLAMF2 and SLAMF4 interact with each other. Their interactions induce signal transduction networks in trans, thereby shaping immune cell-cell communications. Collectively, these receptors modulate a wide range of functions, such as myeloid cell and lymphocyte development, and T and B cell responses to microbes and parasites. In addition, several SLAMF receptors serve as microbial sensors, which either positively or negatively modulate the function of macrophages, dendritic cells, neutrophils, and NK cells in response to microbial challenges. The SLAMF receptor-microbe interactions contribute both to intracellular microbicidal activity as well as to migration of phagocytes to the site of inflammation. In this review, we describe the current knowledge on how the SLAMF receptors and their specific adapters SLAM-associated protein and EAT-2 regulate innate and adaptive immune responses to microbes.

The cell surface receptor Slamf6 modulates innate immune responses during Citrobacter rodentium-induced colitis

The homophilic cell surface receptors CD150 (Slamf1) and CD352 (Slamf6) are known to modulate adaptive immune responses. Although the Th17 response was enhanced in Slamf6(-/-) C57BL/6 mice upon oral infection with Citrobacter rodentium, the pathologic consequences are indistinguishable from an infection of wild-type C57BL/6 mice. Using a reporter-based binding assay, we show that Slamf6 can engage structures on the outer cell membrane of several Gram(-) bacteria. Therefore, we examined whether Slamf6, like Slamf1, is also involved in innate responses to bacteria and regulates peripheral inflammation by assessing the outcome of C. rodentium infections in Rag(-/-) mice. Surprisingly, the pathology and immune responses in the lamina propria of C. rodentium-infected Slamf6(-/-) Rag(-/-) mice were markedly reduced as compared with those of Rag(-/-) mice. Infiltration of inflammatory phagocytes into the lamina propria was consistently lower in Slamf6(-/-) Rag(-/-) mice than in Rag(-/-) animals. Concomitant with the reduced systemic translocation of the bacteria was an enhanced production of IL-22, suggesting that Slamf6 suppresses a mucosal protective program. Furthermore, administering a mAb (330) that inhibits bacterial interactions with Slamf6 to Rag(-/-) mice ameliorated the infection compared with a control antibody. We conclude that Slamf6-mediated interactions of colonic innate immune cells with specific Gram(-) bacteria reduce mucosal protection and enhance inflammation, contributing to lethal colitis that is caused by C. rodentium infections in Rag(-/-) mice.

SLAMF4 Is a Negative Regulator of Expansion of Cytotoxic Intraepithelial CD8+ T Cells That Maintains Homeostasis in the Small Intestine

BACKGROUND & AIMS

Intraepithelial T lymphocyte cells (IEL) are the first immune cells to respond to pathogens; they help maintain the integrity of the epithelial barrier. We studied the function of the mouse glycoprotein Signaling Lymphocyte Activation Molecule Family receptor (SLAMF) 4 (encoded by Slamf4) on the surface of CD8αβ αβ T-cell receptor (TCR)(+) IELs, and the roles of these cells in homeostasis of the small intestine in mice.

METHODS

SLAMF4(-) CD8(+) αβTCR(+) cells isolated from spleens of OT-I Rag1(-/-) mice were induced to express gut-homing receptors and transferred to C57BL/6J mice; levels of SLAMF4(+) cells were measured in small intestine tissues. After administration of anti-CD3 or antigen, with or without anti-SLAM4, to C57BL/6J and Slamf4(-/-) mice, CD8αβ αβTCR(+) IELs were collected; cytokine production and cytotoxicity were measured. Depletion of CX3CR1(+) phagocytes was assessed in mice by live-cell confocal imaging or by cytofluorometry; small intestine tissues were analyzed by histology and inflammation was quantified.

RESULTS

Splenic CD8(+) αβTCR(+) cells began to express SLAMF4 only after migrating to the small intestine. Injection of C57BL/6J mice with anti-SLAMF4 and anti-CD3 increased levels of interleukin 10 and interferon gamma secretion by IEL, compared with injection of anti-CD3 only. Similarly, the number of granzyme B(+) cytotoxic CD8(+) αβTCR(+) IELs increased in Slamf4(-/-) mice after injection of anti-CD3 and anti-SLAMF4, administration of antigen, or injection of anti-CD3. Surprisingly, in vivo activation of CD8αβ(+) IELs with anti-CD3 or antigen caused transient depletion of CX3CR1(+) phagocytes, which was prolonged by co-injection with anti-SLAMF4 or in Slamf4(-/-) mice. Anti-CD3 aggravated inflammation in the small intestines of Slamf4(-/-) mice and Eat2a(-/-)Eat2b(-/-) mice, indicated by flattened villi and crypt hyperplasia.

CONCLUSIONS

In mice, the intestinal environment induces SLAMF4 expression and localization to the surface of CD8(+) αβTCR(+) IELs. Signaling via SLAMF4 controls expansion of cytotoxic CD8αβ(+) IELs, which regulate the reversible depletion of lamina propria phagocytes and inflammation in the small intestine.

Plant-based oral tolerance to hemophilia therapy employs a complex immune regulatory response including LAP+CD4+ T cells

Coagulation factor replacement therapy for the X-linked bleeding disorder hemophilia is severely complicated by antibody ("inhibitor") formation. We previously found that oral delivery to hemophilic mice of cholera toxin B subunit-coagulation factor fusion proteins expressed in chloroplasts of transgenic plants suppressed inhibitor formation directed against factors VIII and IX and anaphylaxis against factor IX (FIX). This observation and the relatively high concentration of antigen in the chloroplasts prompted us to evaluate the underlying tolerance mechanisms. The combination of oral delivery of bioencapsulated FIX and intravenous replacement therapy induced a complex, interleukin-10 (IL-10)-dependent, antigen-specific systemic immune suppression of pathogenic antibody formation (immunoglobulin [Ig] 1/inhibitors, IgE) in hemophilia B mice. Tolerance induction was also successful in preimmune mice but required prolonged oral delivery once replacement therapy was resumed. Orally delivered antigen, initially targeted to epithelial cells, was taken up by dendritic cells throughout the small intestine and additionally by F4/80(+) cells in the duodenum. Consistent with the immunomodulatory responses, frequencies of tolerogenic CD103(+) and plasmacytoid dendritic cells were increased. Ultimately, latency-associated peptide expressing CD4(+) regulatory T cells (CD4(+)CD25(-)LAP(+) cells with upregulated IL-10 and transforming growth factor-β (TGF-β) expression) as well as conventional CD4(+)CD25(+) regulatory T cells systemically suppressed anti-FIX responses.

Migration of myeloid cells during inflammation is differentially regulated by the cell surface receptors Slamf1 and Slamf8

Previous studies have demonstrated that the cell surface receptor Slamf1 (CD150) is requisite for optimal NADPH-oxidase (Nox2) dependent reactive oxygen species (ROS) production by phagocytes in response to Gram- bacteria. By contrast, Slamf8 (CD353) is a negative regulator of ROS in response to Gram+ and Gram- bacteria. Employing in vivo migration after skin sensitization, induction of peritonitis, and repopulation of the small intestine demonstrates that in vivo migration of Slamf1^-/- dendritic cells and macrophages is reduced, as compared to wt mice. By contrast, in vivo migration of Slamf8^-/- dendritic cells, macrophages and neutrophils is accelerated. These opposing effects of Slamf1 and Slamf8 are cell-intrinsic as judged by in vitro migration in transwell chambers in response to CCL19, CCL21 or CSF-1. Importantly, inhibiting ROS production of Slamf8^-/- macrophages by diphenyleneiodonium chloride blocks this in vitro migration. We conclude that Slamf1 and Slamf8 govern ROS–dependent innate immune responses of myeloid cells, thus modulating migration of these cells during inflammation in an opposing manner.

Prevalence, concentrations, and antibiotic sensitivities of Salmonella serovars in poultry from retail establishments in Seattle, Washington

Poultry have been identified as one of the major sources of salmonellosis, with estimates ranging from 10 to 22% of total cases. Despite several advances in the industry and new performance standards, the incidence of salmonellosis in the population has not declined over the last 15 years. Salmonella is pervasive in a wide variety of foods, and thus, estimating its burden resulting from specific food categories has been challenging and plagued with uncertainty due to critical data gaps. The objective of this study was to conduct a year-long market survey (1,322 samples) to help bridge the data gaps on the contamination rates and levels of Salmonella on raw poultry by product type (i.e., breast, thighs, drums, wings, and split breast) and production method (conventional versus organic). The isolates recovered were serotyped and tested for antibiotic sensitivities. A PCR method was utilized for initial screening of samples after an overnight enrichment in tryptic soy broth. Three-tube most-probable-number (MPN) assays and anti-Salmonella immunomagnetic separation methods were utilized to determine the levels of Salmonella and aid with the recovery of Salmonella species, respectively. Eleven percent of the samples were positive for Salmonella. Significant differences in percent positive rates by product type included up to a 4-fold difference in percent positive rates between establishments, ranging from 7 to 31%. Of the samples positive for Salmonella species, 94% had <30 MPN/100 g. Production methods identified as organic or as not using antibiotics had significantly higher rates of recovery of Salmonella. On the other hand, all of the Salmonella isolates that were resistant to two or more antibiotics originated from conventional processing establishments where antibiotics were utilized. In addition, a significant proportion of isolates from conventionally processed products were serotypes clinically relevant to humans.

Glucocorticoid-Induced TNF Receptor Family-Related Protein Ligand is Requisite for Optimal Functioning of Regulatory CD4(+) T Cells

Glucocorticoid-induced tumor necrosis factor receptor family-related protein (TNFRSF18, CD357) is constitutively expressed on regulatory T cells (Tregs) and is inducible on effector T cells. In this report, we examine the role of glucocorticoid-induced TNF receptor family-related protein ligand (GITR-L), which is expressed by antigen presenting cells, on the development and expansion of Tregs. We found that GITR-L is dispensable for the development of naturally occurring FoxP3⁺ Treg cells in the thymus. However, the expansion of Treg in GITR-L^−/− mice is impaired after injection of the dendritic cells (DCs) inducing factor Flt3 ligand. Furthermore, DCs from the liver of GITR-L^−/− mice were less efficient in inducing proliferation of antigen-specific Treg cells in vitro than the same cells from WT littermates. Upon gene transfer of ovalbumin into hepatocytes of GITR-L^−/−FoxP3(GFP) reporter mice using adeno-associated virus (AAV8-OVA) the number of antigen-specific Treg in liver and spleen is reduced. The reduced number of Tregs resulted in an increase in the number of ovalbumin specific CD8⁺ T effector cells. This is highly significant because proliferation of antigen-specific CD8⁺ cells itself is dependent on the presence of GITR-L, as shown by in vitro experiments and by adoptive transfers into GITR-L^−/−Rag^−/− and Rag^−/− mice that had received AAV8-OVA. Surprisingly, administering αCD3 significantly reduced the numbers of FoxP3⁺ Treg cells in the liver and spleen of GITR-L^−/− but not WT mice. Because soluble Fc-GITR-L partially rescues αCD3 induced in vitro depletion of the CD103⁺ subset of FoxP3⁺CD4⁺ Treg cells, we conclude that expression of GITR-L by antigen presenting cells is requisite for optimal Treg-mediated regulation of immune responses including those in response during gene transfer.

Abstract P4-05-03: Unique genetic, epigenetic, and transcriptomic changes in premenopausal breast cancer suggest novel strategies for therapy

Breast cancer in premenopausal women (preM) is frequently associated with worse prognosis compared to that in postmenopausal women (postM) even when controlling for prognostic variables. In particular, preM ER+ tumors have a poor prognosis on endocrine therapy. There is, however, a paucity of studies characterizing molecular alterations in premenopausal tumors, a potential avenue for finding personalized therapies for this group of women.

We analyzed gene expression, CNV, methylation, and somatic mutations in tumors from preM (≤45; ER+ n = 110, and ER- n = 39) and postM (≥55, ER+ n = 392, and ER- n = 102) women in The Cancer Genome Atlas (TCGA). Unbiased hierarchical clustering of 2,900 most variably expressed genes (using both RNA-seq and Agilent expression array data) in the whole dataset (n = 643) identified four major subtypes which correlated highly with the PAM50 defined subtypes LumA, LumB, Basal and HER2; however, there wasn't any separation between preM and postM samples. Similarly, principal component analysis using 10,000 genes with the highest inter-quartile range (IQR) demonstrated high similarity across preM and postM samples. Direct examination of gene expression differences between PreM and PostM ER+ tumors using unpaired t-test (5% FDR) identified 3,044 differentially expressed genes. The genes most upregulated in premenopausal tumors included AREG, TFPI2, MSMB, TCN1, and GLRA3. Ingenuity Pathway Analysis revealed a highly significant enrichment for TGFb (p&lt;1.9E-16) pathway activity in preM tumors. Intriguingly, no significant gene expression differences between preM and postM ER- tumors were identified. We thus then focused on genetic and epigenetic alterations that may underlie these transcriptomic changes in ER+ preM tumors.

Comparison of methylation (450K Illumina array) between preM and postM ER+ tumors showed a difference in 1% (n = 1,738) of the probes. Genes with the largest difference included ESR1, SIM2, and KLF6. Significant differences in DNA copy number variation (Affymetrix SNP 6.0 array) were also identified in ER+ preM tumors. A number of somatic mutations were significantly enriched in preM ER+ tumors including DSPP and GATA3. Integrated analysis also showed that approximately half of the observed differences in gene expression are driven by CNVs.

Conclusion: Our in silico study has identified a number of genes and pathways which are significantly altered between preM and postM ER+ breast cancer. Distinct genetic and epigenetic differences suggest unique etiology for some preM tumors. Currently ongoing Paradigm analysis, and confirmatory studies using METABRIC data are expected to further identify pathways that could specifically be targeted in premenopausal breast cancer.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-05-03.

Glucocorticoid-induced TNF receptor family-related protein ligand regulates the migration of monocytes to the inflamed intestine

Glucocorticoid-induced TNF receptor family-related protein (GITR) regulates the function of both T cells and antigen-presenting cells (APCs), while the function of GITR ligand (GITR-L) is largely unknown. Here we evaluate the role of GITR-L, whose expression is restricted to APCs, in the development of enterocolitis. On injecting naive CD4(+) T cells, GITR-L(-/-)Rag(-/-) mice develop a markedly milder colitis than Rag(-/-) mice, which correlates with a 50% reduction of Ly6C(+)CD11b(+)MHCII(+) macrophages in the lamina propria and mesenteric lymph nodes. The same result was observed in αCD40-induced acute colitis and during peritonitis, suggesting an altered monocyte migration. In line with these observations, the number of nondifferentiated monocytes was approximately 3-fold higher in the spleen of GITR-L(-/-)Rag(-/-) mice than in Rag(-/-) mice after αCD40 induction. Consistent with the dynamic change in the formation of an active angiotensin II type 1 receptor (AT1) dimer in GITR-L(-/-) splenic monocytes during intestinal inflammation, the migratory capability of splenic monocytes from GITR-L-deficient mice was impaired in an in vitro transwell migration assay. Conversely, αGITR-L reduces the number of splenic Ly6C(hi) monocytes, concomitantly with an increase in AT1 dimers. We conclude that GITR-L regulates the number of proinflammatory macrophages in sites of inflammation by controlling the egress of monocytes from the splenic reservoir.

Mechanism of oral tolerance induction to therapeutic proteins

Oral tolerance is defined as the specific suppression of humoral and/or cellular immune responses to an antigen by administration of the same antigen through the oral route. Due to its absence of toxicity, easy administration, and antigen specificity, oral tolerance is a very attractive approach to prevent unwanted immune responses that cause a variety of diseases or that complicate treatment of a disease. Many researchers have induced oral tolerance to efficiently treat autoimmune and inflammatory diseases in different animal models. However, clinical trials yielded limited success. Thus, understanding the mechanisms of oral tolerance induction to therapeutic proteins is critical for paving the way for clinical development of oral tolerance protocols. This review will summarize progress on understanding the major underlying tolerance mechanisms and contributors, including antigen presenting cells, regulatory T cells, cytokines, and signaling pathways. Potential applications, examples for therapeutic proteins and disease targets, and recent developments in delivery methods are discussed.

Glucocorticoid-induced TNF receptor family related protein ligand regulates the egress of monocytes from the spleen (P3288)

Glucocorticoid-Induced TNF Receptor family-related protein Ligand (GITR-L) is expressed on antigen presenting cells. Surprisingly, GITR-L−/−Rag−/− mice develop a markedly milder colitis than Rag−/− mice upon transferring CD4+CD45RBhi T cells or by administering agonistic anti-CD40 antibody. In both colitis models as well as in a peritonitis model a reduced number of Ly6C+CD11b+MHCII+ macrophages was found in the inflamed sites of GITR-L−/− mice. By contrast, the number of non-differentiated monocytes was approximately three-fold higher in the spleen of inflamed GITR-L−/−Rag−/− mice than in Rag−/− mice. The formation of an active dimer of the angiotensin II type 1 receptor (AT-1) by splenic monocytes, which regulates their egress, was dynamically affected by the GITR-L deficiency. Infusion of Angiotensin II caused retention of splenic monocytes in GITR-L−/− but not wt mice. We conclude that upon induction of inflammation GITR-L regulates egress of monocytes from the spleen, thus impacting intestinal homeostasis in mice.

Circulatory antigen processing by mucosal dendritic cells controls CD8(+) T cell activation

Circulatory antigens transit through the small intestine via the fenestrated capillaries in the lamina propria prior to entering into the draining lymphatics. But whether or how this process controls mucosal immune responses remains unknown. Here we demonstrate that dendritic cells (DCs) of the lamina propria can sample and process both circulatory and luminal antigens. Surprisingly, antigen cross-presentation by resident CX3CR1(+) DCs induced differentiation of precursor cells into CD8(+) T cells that expressed interleukin-10 (IL-10), IL-13, and IL-9 and could migrate into adjacent compartments. We conclude that lamina propria CX3CR1(+) DCs facilitate the surveillance of circulatory antigens and act as a conduit for the processing of self- and intestinally absorbed antigens, leading to the induction of CD8(+) T cells, that partake in the control of T cell activation during mucosal immune responses.

Cutting edge: Slamf8 is a negative regulator of Nox2 activity in macrophages

Slamf8 (CD353) is a cell surface receptor that is expressed upon activation of macrophages (MΦs) by IFN-γ or bacteria. In this article, we report that a very high NADPH oxidase (Nox2) enzyme activity was found in Slamf8(-/-) MΦs in response to Escherichia coli or Staphylococcus aureus, as well as to PMA. The elevated Nox2 activity in Slamf8(-/-) MΦs was also demonstrated in E. coli or S. aureus phagosomes by using a pH indicator system and was further confirmed by a reduction in the enzyme activity after transfection of the receptor into Slamf8-deficient primary MΦs or RAW 264.7 cells. Upon exposure to bacteria or PMA, protein kinase C activity in Slamf8(-/-) MΦs is increased. This results in an enhanced phosphorylation of p40phox, one key component of the Nox2 enzyme complex, which, in turn, leads to greater Nox2 activity. Taken together, the data show that, in response to inflammation-associated stimuli, the inducible receptor Slamf8 negatively regulates inflammatory responses.

Slamf1 controls monocyte / macrophage migration in experimental colitis. (117.5)

Signaling lymphocyte activation molecule (Slamf1) is a T cell co-stimulatory molecule and a regulator of cytokine production by macrophages and dendritic cells. Because Slamf1 positively regulates microbicidal mechanisms in macrophages, we evaluate whether Slamf1 would affect enterocolitis. To induce colitis, mouse CD45RBhi CD4+ T cells were transferred into RAG-/- or Slamf1-/- RAG-/- recipient mice. In a second set of experiments, an agonistic αCD40 antibody was administered to the same recipient strains to induce colitis. Whilst the absence of Slamf1 in RAG-/- recipients mitigated colitis, the function of disease-causing effector or regulatory T cells was not affected by the ablation of the receptor. Surprisingly, in Slamf1-/- mice monocyte / macrophage migration into the inflamed tissue was impaired not only in αCD40-induced colitis but also in two other in vivo models of inflammation: thioglycolate induced peritonitis and in an “air pouch” model in response to TNFα. Administering αSlamf1 to RAG-/- mice ameliorated enterocolitis and altered this migration. Slamf1 is a key contributor to the innate immune responses during experimental colitis by affecting the migration of monocytes / macrophages to the sites of inflammation. As αSlamf1 also mitigates the pathogenesis of colitis, SLAMF1 should be a plausible therapeutic target in treating inflammatory bowel diseases.

Slamf8 is a negative regulator of Nox2 activity and antigen presentation by macrophages and dendritic cells. (172.16)

Slamf8 (CD353) is a novel cell surface receptor that is expressed upon activation of resident peritoneal macrophages by interferon-gamma or bacteria. In studying innate immune responses of Slamf8-/- macrophages and dendritic cells, we found a very high activity of the Nox2 enzyme, not only in response to E.coli or S.aureus, but also to phorbol myristate acetate. Thus, Slamf8 acts as a negative regulator of Nox2 activity, which was confirmed by a reduction of the enzyme activity after transfection of the receptor into Slamf8-deficient primary or RAW 264.7 macrophages. The elevated Nox2 activity in Slamf8-/- macrophages partially reverted lowering of the pH in E.coli or S.aureus phagosomes. Consequently, in Slamf8-/- macrophages and dendritic cells MHC Class II antigen presentation to CD4 T+ cells is dramatically increased compared to wt cells. Taken together, the data show that upon response to inflammation-associated stimuli the inducible receptor Slamf8 negatively regulates antigen presentation.

Regulation of expression of SLAMF4 on the surface of mucosal lymphocytes (120.13)

SLAMF4 is a cell surface receptor, which is primarily known as a regulator of cytotoxicity and cytokine secretion by mouse NK cells upon engagement with its counter-structure CD48. Here, we found SLAMF4 is highly expressed on the surface of most mucosal CD8+ T cells, whereas it is only expressed on some CD44+ CD8+ splenic cells. Upon transfer of naïve SLAMF4− CD8+ T cells derived from Thy1.2+ B6 mice into Thy1.2− B6, donor cells were found to express SLAMF4 after entry into the mucosa. The increase in SLAMF4+ CD8+ cells was due to upregulation of the receptor gene rather than to expansion of a small subset of memory CD8+ T cells. Consistent with the high level of IL-15 in the intestinal mucosa and its requirement for the maintenance of memory CD8+ T cells, we found that recombinant IL-15 induces SLAMF4, particularly the short isoform of SLAMF4, expression on CD8+ T cells. Costimulation with αSLAMF4 significantly increased the αCD3ϵ-induced infiltration of CD8+ T cells in small intestine and exacerbated the inflammation in the small intestine of IL-10-IRES-GFP reporter mouse. As control, αSLAMF4 alone did not cause inflammation in the intestine. In conclusion, the differential expression on mucosal CD8+ T cells as well as the dual nature of SLAMF4 function suggests that SLAMF4 might be involved in regulating the fine balance between the maintenance of tolerance and immune surveillance in the intestinal mucosa.

GITR on the surface of antigen presenting cells, but not on T cells, regulates the pathogenesis of CD4+ T cell-mediated experimental colitis (120.3)

The receptor GITR is thought to function on the surface of regulatory and activated effector CD4+ T cells. To better understand the role of GITR in in vivo immune responses, we use an established experimental colitis model. Chronic enterocolitis was induced by the transfer of wt or GITR−/− CD4+ T cells into either GITR−/− x Rag−/− or Rag−/− recipients. When non-fractionated CD4+ cells from either wt or GITR−/− donors were transferred, colitis unexpectedly developed in GITR−/− x Rag−/−, but not in Rag−/− recipients. In these mice, the percentage of Treg and Th17 cells is decreased, whilst that of Th1 cells increased. Furthermore, Tregs fail to prevent colitis in GITR−/− x Rag−/− recipients. This is not due to an aberrant function of GITR−/− Treg or Teff cells, but is caused by an imbalance in the number of tolerogenic CD103+ and PDCA1+ plasmacytoid dendritic cells in the GITR−/− mouse. This in turn impairs Treg development and expands the Th1 population in GITR−/− x Rag−/− recipients upon the transfer of non-fractionated CD4+ cells. We conclude that for the induction of colitis, GITR is dispensable on the surface of Treg and Teff cells, nor do GITR-L / GITR interactions on T cells play a role in controlling the disease. GITR, however, controls in vivo DC and monocyte development and in its absence aggravated chronic enterocolitis is caused by an imbalance of colitogenic Th1 cells and regulatory T cells.

Improvement of A21978C production in Streptomyces roseosporus by reporter-guided rpsL mutation selection

AIMS

Daptomycin, one of the A21978C factors produced by Streptomyces roseosporus, is an acidic cyclic lipopeptide antibiotic with potent activity against a variety of Gram-positive pathogens. To increase the titre of this extensively used and clinically important antibiotic, we applied a reported-guided rpsL mutation selection system to generate strains producing high levels of A21978C.

METHODS AND RESULTS

In the reporter design, dptE was chosen as the overexpressing target, and neo-encoding neomycin phosphotransferase as the reporter. Using this reporter-guided selection system, 20% of the selected, streptomycin-resistant mutants produced greater amounts of A21978C than the starting strain. The selection system increased the screening efficiency about 10-fold with a frequency of 1·7% A21978C overproducing strains among str(r) mutants. A21978C production was increased approximately 2·2-fold in the rpsL K43N mutant.

CONCLUSIONS

The combination of ribosome engineering and reporter-guided mutant selection generated an A21978C overproducing strain that produced about twice as much A21978C as the parental strain.

SIGNIFICANCE AND IMPACT OF THE STUDY

The strategies presented here, which integrated the advantages of both ribosome engineering and reporter-guided mutation selection, could be applied to other bacteria to improve their yield of secondary metabolites.

Glucocorticoid-induced tumor necrosis factor receptor family-related protein regulates CD4(+)T cell-mediated colitis in mice

BACKGROUND & AIMS

The glucocorticoid-induced tumor necrosis factor receptor family-related protein (GITR; also called TNFRSF18 or CD357) regulates the T cell-mediated immune response and is present on surfaces of regulatory T (Treg) cells and activated CD4(+) T cells. We investigated the roles of GITR in the development of colitis in mice.

METHODS

Chronic enterocolitis was induced by the transfer of wild-type or GITR(-/-) CD4(+) T cells to GITR(-/-) × Rag(-/-) or Rag(-/-) mice. We determined the severity of colitis by using the disease activity index; measured levels of inflammatory cytokines, T cells, and dendritic cells; and performed histologic analysis of colon samples.

RESULTS

Transfer of nonfractionated CD4(+) cells from wild-type or GITR(-/-) donors induced colitis in GITR(-/-) × Rag(-/-) but not in Rag(-/-) mice. Among mice with transfer-induced colitis, the percentage of Treg and T-helper (Th) 17 cells was reduced but that of Th1 cells increased. Treg cells failed to prevent colitis in GITR(-/-) × Rag(-/-) recipients; this was not the result of aberrant function of GITR(-/-) Treg or T effector cells but resulted from an imbalance between the numbers of tolerogenic CD103(+) and PDCA1(+) plasmacytoid dendritic cells in GITR(-/-) mice. This imbalance impaired Treg cell development and expanded the Th1 population in GITR(-/-) × Rag(-/-) mice following transfer of nonfractionated CD4(+) cells.

CONCLUSIONS

GITR is not required on the surface of Treg and T effector cells to induce colitis in mice; interactions between GITR and its ligand are not required for induction of colitis. GITR instead appears to control dendritic cell and monocyte development; in its absence, mice develop aggravated chronic enterocolitis via an imbalance of colitogenic Th1 cells and Treg cells.

A novel isoform of the Ly108 gene ameliorates murine lupus

The expression of the new Ly108 isoform H1 weakens lupus-like disease of C57BL/6.Sle1b mice.

Studies of human systemic lupus erythematosus patients and of murine congenic mouse strains associate genes in a DNA segment on chromosome 1 with a genetic predisposition for this disease. The systematic analysis of lupus-prone congenic mouse strains suggests a role for two isoforms of the Ly108 receptor in the pathogenesis of the disease. In this study, we demonstrate that Ly108 is involved in the pathogenesis of lupus-related autoimmunity in mice. More importantly, we identified a third protein isoform, Ly108-H1, which is absent in two lupus-prone congenic animals. Introduction of an Ly108-H1–expressing transgene markedly diminishes T cell–dependent autoimmunity in congenic B6.Sle1b mice. Thus, an immune response–suppressing isoform of Ly108 can regulate the pathogenesis of lupus.

SLAM is a microbial sensor that regulates bacterial phagosome functions in macrophages

Phagocytosis is a pivotal process by which macrophages eliminate microorganisms after recognition by pathogen sensors. Here we unexpectedly found that the self ligand and cell surface receptor SLAM functioned not only as a costimulatory molecule but also as a microbial sensor that controlled the killing of gram-negative bacteria by macrophages. SLAM regulated activity of the NADPH oxidase NOX2 complex and phagolysosomal maturation after entering the phagosome, following interaction with the bacterial outer membrane proteins OmpC and OmpF. SLAM recruited a complex containing the intracellular class III phosphatidylinositol kinase Vps34, its regulatory protein kinase Vps15 and the autophagy-associated molecule beclin-1 to the phagosome, which was responsible for inducing the accumulation of phosphatidylinositol-3-phosphate, a regulator of both NOX2 function and phagosomal or endosomal fusion. Thus, SLAM connects the gram-negative bacterial phagosome to ubiquitous cellular machinery responsible for the control of bacterial killing.

GITR engagement preferentially enhances proliferation of functionally competent CD4+CD25+FoxP3+ regulatory T cells

Naturally occurring regulatory T cells (Treg) express high levels of glucocorticoid-induced tumour necrosis factor receptor (GITR). However, studies of the role of GITR in Treg biology has been complicated by the observation that upon activation effector CD4(+) T (Teff) cells also express the receptor. Here, we dissect the contribution of GITR-induced signaling networks in the expansion and function of FoxP3(+) Treg. We demonstrate that a high-affinity soluble Fc-GITR-L dimer, in conjugation with alphaCD3, specifically enhances in vitro proliferation of Treg, which retain their phenotypic markers (CD25 and FoxP3) and their suppressor function, while minimally affecting Teff cells. Furthermore, Fc-GITR-L does not impair Teff susceptibility to suppression, as judged by cocultures employing GITR-deficient and GITR-sufficient CD4(+) T-cell subsets. Notably, this expansion of Treg could also be seen in vivo, by injecting FoxP3-IRES-GFP mice with Fc-GITR-L even in the absence of antigenic stimulation. In order to test the efficacy of these findings therapeutically, we made use of a C3H/HeJ hemophilia B-prone mouse model. The use of liver-targeted human coagulation factor IX (hF.IX) gene therapy in this model has been shown to induce liver toxicity and the subsequent failure of hF.IX expression. Interestingly, injection of Fc-GITR-L into the hemophilia-prone mice that were undergoing liver-targeted hF.IX gene therapy increased the expression of F.IX and reduced the anticoagulation factors. We conclude that GITR engagement enhances Treg proliferation both in vitro and in vivo and that Fc-GITR-L may be a useful tool for in vivo tolerance induction.

Blocking CD27-CD70 costimulatory pathway suppresses experimental colitis

The pathogenesis of human inflammatory bowel disease (IBD) and most experimental models of IBD is dependent on the activation and expansion of CD4(+) T cells via interaction with mucosal APCs. The costimulatory receptor CD70 is transiently expressed on the surface of conventional dendritic cells, but is constitutively expressed by a unique APC population in the intestinal lamina propria. We used two experimental IBD models to evaluate whether interfering the interaction between CD70 and its T cell ligand CD27 would affect the development of colitis. Adoptive transfer of naive CD27-deficient CD45RB(high) CD4(+) T cells into Rag-1(-/-) mice resulted in significantly less disease than when wild-type CD45RB(high)CD4(+) T cells were used. Moreover, a monoclonal anti-CD70 Ab prevented the disease caused by the transfer of wild-type CD45RB(high) CD4(+) T cells into Rag-1(-/-) mice and the same Ab also ameliorated an established disease. The colitis associated proinflammatory cytokines IL-6, TNF-alpha and IFN-gamma were significantly reduced after anti-CD70 Ab treatment, suggesting an overall reduction in inflammation due to blockade of pathogenic T cell expansion. Anti-CD70 Ab treatment also suppressed trinitrobenzene sulfonic acid-induced colitis in SJL/J mice. Because anti-CD70 Ab treatment suppressed multiple proinflammatory cytokines, this may be a more potent therapeutic approach for IBD than blockade of individual cytokines.

Use of bacterial two-hybrid system to investigate the molecular interaction between the regulators NifA and NifL of Enterobacter cloacae

Expression of the nitrogen fixation (nif) genes is tightly regulated by two proteins NifA and NifL in the gamma-subdivision of the proteobacteria. NifA is a transcriptional activator, which can be inactivated by NifL in the presence of oxygen or excess fixed nitrogen. A direct interaction between E. cloacae NifL and NifA was detected using the bacterial two-hybrid system. This interaction was accelerated in the presence of fixed nitrogen, while oxygen had no effect. NifL proteins, with their C-terminus being deleted, completely lost the ability to interact with NifA. The data suggest that the C-terminal domain of NifL acts as a sensor of the nitrogen status of the cell and mediates interaction with NifA.

Association of the 54-nucleotide repeat polymorphism of hPer3 with heroin dependence in Han Chinese population

Circadian clock genes have the function of producing circadian rhythm. They are also implicated in the origin or development of many diseases such as cancers and neuropsychiatric diseases. The purpose of this study is to determine whether the 54-nucleotide repeat polymorphism of hPer3, one of the circadian clock genes, associates with heroin dependence. DNA samples were obtained from 209 Chinese heroin-dependent subjects and 249 Chinese healthy controls. The 54-nucleotide repeat polymorphism was detected by polymerase chain reaction and DNA agarose gel electrophoresis. The frequency of four-repeat allele was significantly higher (chi(2)= 10.64, P = 0.001; corrected for multiple tests, P = 0.003) in the mixed gender heroin-dependent subject group (four repeat: 0.89, five repeat: 0.11) than in the mixed gender control group (four repeat: 0.81, five repeat: 0.19); the frequency of four-repeat allele was also significantly higher (chi(2)= 10.00, P = 0.002; corrected for multiple tests, P = 0.006) in the male heroin-dependent subject group (four repeat: 0.89, five repeat: 0.11) than in the male control group (four repeat: 0.81, five repeat: 0.19); for females, no significant trend was observed with the 54-nucleotide repeat polymorphism between the heroin-dependent subject group and the control group. Our results suggest that the 54-nucleotide repeat polymorphism of hPer3 significantly associates with heroin dependence at the allele frequency level and may be a potential risk factor for the development of heroin dependence.

Chirality and polarity transfers between bent-core smectic liquid-crystal substances

Liquid-crystal phases with both solid and liquid characteristics are unique, since they exhibit chirality on both molecular and mesoscopic levels under special circumstances. We have studied binary composites formed by mixing of a chiral dimer (B-Ch), in which a bent core is covalently linked to a promesogenic cholesterol unit through a flexible spacer, and an achiral bent-core mesogen having two vicinal fluorine atoms (B-2F). The pure materials show smectic phases featuring C2 symmetry. The dimer B-Ch displays conventional chiral smectic C (SmC*) phase with a chirality--induced polarization P(c) approximately 30 nC/cm2, whereas B-2F possesses synclinic and anticlinic antiferroelectric "banana" smectic (SmCP) phase with a relatively high-polarization (P(b)) value of about 900 nC/cm(2). Mixing these two materials we were able to measure P(c), and we have verified that the molecular chirality contributes to the polarization of banana phases only in synclinic configurations.

Ferroelectricity of a bent-core material with cholesteryl terminal chain

We have studied the phase sequence and physical properties of an asymmetric bent-core material with a chiral rigid cholesteryl moiety, and a flexible achiral alkyl side chain at the other end. The combination of the achiral bent core with the chiral cholesteryl unit results in properties different from those of both the usual calamitic and bent-core materials. We find that the presence of the bent core unit induces a wide-temperature-range optically isotropic (probably BPIII) mesophase between the isotropic and cholesteric (chiral nematic) phases. Below the cholesteric phase a ferroelectric smectic-C* structure occurs in which the bent-core units do not seem to form a polar close packing.

Breast cancer resistance protein-mediated topotecan resistance in ovarian cancer cells

Overexpression of breast cancer resistance protein (BCRP) and mitoxantrone (MX) resistance protein can confer resistance to a variety of cytostatic drugs, such as MX, topotecan (TPT), doxorubicin, and daunorubicin. This study investigates the role of BCRP in resistance of ovarian cancer to TPT treatment. We have developed TPT-resistant human ovarian cancer cell line. Intracellular concentration of fluorescent dye rhodamine 123 (Rh123) was measured by flow cytometry. The expression of several membrane transporter proteins including P-glycoprotein (P-gp), multidrug resistance protein 1 (MRP1), and BCRP were determined by reverse transcription-polymerase chain reaction and Western blotting. The Rh123 concentration in parental cells was approximately three times of those in TPT-resistant cells. In contrast to undetectable level of P-gp messenger RNA (mRNA) and minimal level of MRP1 expression in TPT-resistant cells, overexpression of both the BCRP mRNA and the protein was detected in these cells. Introduction of antisense-phosphorothioate oligonucleotide derived from BCRP mRNA into TPT-resistant cells resulted in a significant increase in the concentration of intracellular Rh123. These results suggested a novel mechanism in which a reduced intracellular drug concentration may be mediated by BCRP gene products in human ovarian cancer cells.

A quantitative evaluation of peroxidase inhibitors for tyramide signal amplification mediated cytochemistry and histochemistry

Many peroxidase inhibitors have been used in horseradish peroxidase (HRP) mediated immunostaining and in situ hybridization to quench background peroxidase activity. However, the efficacy of these inhibitors has been controversial, partially due to the lack of a quantitative study. Tyramide signal amplification (TSA) is much more sensitive than other HRP-mediated methods but its super-sensitivity also demands effective inhibition of background peroxidase activity. In searching for an effective peroxidase inhibitor, we have systematically evaluated the efficacy of several peroxidase inhibitors by quantifying the fluorescence intensity in cultured fibroblasts and tissue sections treated with the inhibitors. For cultured cells, 0.05 mM of phenylhydrazine and 1 unit/ml of glucose oxidase gave only moderate inhibition of HRP activity while 1 mM of sodium azide (NaN(3)), 3% of hydrogen peroxide (H(2)O(2)), NaN(3)/H(2)O(2) combined and 0.02 N hydrochloric acid (HCl) provided more complete inhibition. However, the inhibitory effect of NaN(3)/H(2)O(2) is reversible upon removal of the inhibitors and followed by incubation and wash to mimic antibody interactions. Similar results were obtained from rat skin wound tissues that have strong endogenous peroxidase activity. Our results recommend the use of HCl and caution the use of phenylhydrazine, glucose oxidase, NaN(3) and H(2)O(2) as potent peroxidase inhibitors.

Identification and characterization of two related murine genes, Eat2a and Eat2b, encoding single SH2-domain adapters

Human EAT-2 (SH2D1B) and SLAM-associated protein (SAP) (SH2D1A) are single SH2-domain adapters, which bind to specific tyrosine residues in the cytoplasmic tail of six signaling lymphocytic activation molecule (SLAM) (SLAMF1)-related receptors. Here we report that, unlike in humans, the mouse and rat Eat2 genes are duplicated with an identical genomic organization. The coding regions of the mouse Eat2a and Eat2b genes share 91% identity at the nucleotide level and 84% at the protein level; similarly, segments of introns are highly conserved. Whereas expression of mouse Eat2a mRNA was detected in multiple tissues, Eat2b was only detectable in mouse natural killer cells, CD8+ T cells, and ovaries, suggesting a very restricted tissue expression of the latter. Both the EAT-2A and EAT-2B coimmunoprecipitated with mouse SLAM in transfected cells and augmented tyrosine phosphorylation of the cytoplasmic tail of SLAM. Both EAT-2A and EAT-2B bind to the Src-like kinases Fyn, Hck, Lyn, Lck, and Fgr, as determined by a yeast two-hybrid assay. However, unlike SAP, the EAT-2 proteins bind to their kinase domains and not to the SH3 domain of these kinases. Taken together, the data suggest that both EAT-2A and EAT-2B are adapters that recruit Src kinases to SLAM family receptors using a mechanism that is distinct from that of SAP.

Electrorotation of colloidal particles in liquid crystals

We present the first observations of dc electric-field-induced rotational motion of finite particles in liquid crystals. We show that the electrorotation is essentially identical to the well-known Quincke rotation, which in liquid crystals triggers an additional translational motion at higher fields. In the smectic phase the translational motion is confined to the two-dimensional geometry of smectic layers, in contrast to the isotropic and nematic phases, where the particles can move in all three dimensions. We demonstrate that by a proper analysis of the electrorotation, one can determine the in-plane viscosity of smectic liquid crystals. This method needs only a small amount of material, does not require uniform alignment over large areas, and enables probing rheological properties locally.