ST6GAL1 sialyltransferase promotes acinar to ductal metaplasia and pancreatic cancer progression

The role of aberrant glycosylation in pancreatic ductal adenocarcinoma (PDAC) remains an under-investigated area of research. In this study, we determined that ST6 β-galactoside α2,6 sialyltransferase 1 (ST6GAL1), which adds α2,6-linked sialic acids to N-glycosylated proteins, was upregulated in patients with early-stage PDAC and was further increased in advanced disease. A tumor-promoting function for ST6GAL1 was elucidated using tumor xenograft experiments with human PDAC cells. Additionally, we developed a genetically engineered mouse (GEM) model with transgenic expression of ST6GAL1 in the pancreas and found that mice with dual expression of ST6GAL1 and oncogenic KRASG12D had greatly accelerated PDAC progression compared with mice expressing KRASG12D alone. As ST6GAL1 imparts progenitor-like characteristics, we interrogated ST6GAL1's role in acinar to ductal metaplasia (ADM), a process that fosters neoplasia by reprogramming acinar cells into ductal, progenitor-like cells. We verified ST6GAL1 promotes ADM using multiple models including the 266-6 cell line, GEM-derived organoids and tissues, and an in vivo model of inflammation-induced ADM. EGFR is a key driver of ADM and is known to be activated by ST6GAL1-mediated sialylation. Importantly, EGFR activation was dramatically increased in acinar cells and organoids from mice with transgenic ST6GAL1 expression. These collective results highlight a glycosylation-dependent mechanism involved in early stages of pancreatic neoplasia.

Interactions between H. pylori and the Gastric Microbiome: Impact on Gastric Homeostasis and Disease

Like many seemingly inhospitable environments on our planet, the highly acidic human stomach harbors a diverse bacterial microflora. The best-known member of the human gastric flora, Helicobacter pylori, causes a number of gastric diseases, including peptic ulcer disease and gastric adenocarcinoma. In the absence of Helicobacter pylori infection, the gastric microbiota displays some features similar to the oral cavity with Firmicutes the most common phylum, followed by Proteobacteria and Bacteroidetes. When present, H. pylori dominates the gastric microbiome and reduces diversity and composition of other taxa. The composition of the gastric microbiome also is altered in the setting of proton pump inhibitor therapy and gastric neoplasia. This review summarizes foundational and recent studies that have investigated the composition of the human gastric microbiome in a variety of patient groups, with a focus on potential mechanisms involved in regulation of gastric microbial community structure.

Effects of Racism on Oral Health in the United States

This paper comments on the Effects of Racism on Oral Health in the United States (US). It provides the background and sets the stage to raise questions about race: how was race defined originally, what exactly is race, and how have racial categories been enumerated? Following this path, the paper broadens the scope of view regarding data attributable to racial categories pointing to social and cultural factors that influence overall health outcomes, particularly those related to oral health. Oral health researchers, advocates, providers, administrators, program planners, and funders, among others rely on data, often compiled by racial categories. We should be aware of potential vagaries that can accompany race-based data, and its interpretation and application, regarding oral health. The paper suggests we should be mindful of other influences that affect documented differences among populations regarding their oral health status.

Modulation of glycosyltransferase ST6Gal-I in gastric cancer-derived organoids disrupts homeostatic epithelial cell turnover

Programmed cell death promotes homeostatic cell turnover in the epithelium but is dysregulated in cancer. The glycosyltransferase ST6Gal-I is known to block homeostatic apoptosis through α2,6-linked sialylation of the death receptor TNFR1 in many cell types. However, its role has not been investigated in gastric epithelial cells or gastric tumorigenesis. We determined that human gastric antral epithelium rarely expressed ST6Gal-I, but the number of ST6Gal-I-expressing epithelial cells increased significantly with advancing premalignancy leading to cancer. The mRNA expression levels of ST6GAL-I and SOX9 in human gastric epithelial cells correlated positively with one another through the premalignancy cascade, indicating that increased epithelial cell expression of ST6Gal-I is associated with premalignant progression. To determine the functional impact of increased ST6Gal-I, we generated human gastric antral organoids from epithelial stem cells and differentiated epithelial monolayers from gastric organoids. Gastric epithelial stem cells strongly expressed ST6Gal-I, suggesting a novel biomarker of stemness. In contrast, organoid-derived epithelial monolayers expressed markedly reduced ST6Gal-I and underwent TNF-induced, caspase-mediated apoptosis, consistent with homeostasis. Conversely, epithelial monolayers generated from gastric cancer stem cells retained high levels of ST6Gal-I and resisted TNF-induced apoptosis, supporting prolonged survival. Protection from TNF-induced apoptosis depended on ST6Gal-I overexpression, because forced ST6Gal-I overexpression in normal gastric stem cell-differentiated monolayers inhibited TNF-induced apoptosis, and cleavage of α2,6-linked sialic acids from gastric cancer organoid-derived monolayers restored susceptibility to TNF-induced apoptosis. These findings implicate up-regulated ST6Gal-I expression in blocking homeostatic epithelial cell apoptosis in gastric cancer pathogenesis, suggesting a mechanism for prolonged epithelioid tumor cell survival.

Cytomegalovirus Blocks Macrophage TLR-mediated Tolerance through the Down-regulation of microRNA-146a to Enhance and Prolong Inducible Inflammatory Responses

Cytomegalovirus (CMV), a β-herpesvirus that persistently infects circulating monocytes, causes severe mucosal inflammation in the setting of immunosuppression. My laboratory has shown that CMV infection of monocytes upregulates toll-like receptor (TLR) expression and key components of the NF-κB signal transduction pathway, resulting in enhanced TLR-inducible inflammatory cytokine gene transcription and prompt, albeit transient, inflammatory cytokine production. However, the role of CMV in prolonged inflammation is not known. Here I investigated whether CMV prolongs macrophage-mediated inflammation by inhibiting tolerance to TLR stimulation, the process in which macrophages undergo profound down-regulation of inflammatory cytokine production after 24 hours. In addition to NF-κB induction of inflammatory cytokine production, NF-κB signaling induces microRNA146a (miR-146a), a regulatory miRNA that is induced 12 hours after the induction of inflammatory cytokine genes. Once transcribed, miR-146a feeds back to block IRAK1 and TRAF6, resulting in the downregulation of NF-κB-mediated gene transcription after 24 hours, thereby causing macrophages to become tolerant to subsequent TLR stimulation. Here we show that CMV potently suppresses miR-146a expression, preventing miR-146a blockade of the signal proteins IRAK1 and TRAF6 to promote NF-κB signal transduction. Thus, CMV suppression of macrophage miR-146a provides a mechanism by which CMV breaks macrophage tolerance to TLR stimulation, thereby promoting prolonged cytokine release. In conclusion, CMV enhances early TLR4- and TLR5-inducible cytokine production and blocks TLR tolerance, leading to prolonged cytokine-mediated inflammation.

CD103 (αE Integrin) Undergoes Endosomal Trafficking in Human Dendritic Cells, but Does Not Mediate Epithelial Adhesion

Dendritic cell (DC) expression of CD103, the α subunit of αEβ7 integrin, is thought to enable DC interactions with E-cadherin-expressing gastrointestinal epithelia for improved mucosal immunosurveillance. In the stomach, efficient DC surveillance of the epithelial barrier is crucial for the induction of immune responses to H. pylori, the causative agent of peptic ulcers and gastric cancer. However, gastric DCs express only low levels of surface CD103, as we previously showed. We here tested the hypothesis that intracellular pools of CD103 in human gastric DCs can be redistributed to the cell surface for engagement of epithelial cell-expressed E-cadherin to promote DC-epithelial cell adhesion. In support of our hypothesis, immunofluorescence analysis of tissue sections showed that CD103+ gastric DCs were preferentially localized within the gastric epithelial layer. Flow cytometry and imaging cytometry revealed that human gastric DCs expressed intracellular CD103, corroborating our previous findings in monocyte-derived DCs (MoDCs). Using confocal microscopy, we show that CD103 was present in endosomal compartments, where CD103 partially co-localized with clathrin, early endosome antigen-1 and Rab11, suggesting that CD103 undergoes endosomal trafficking similar to β1 integrins. Dynamic expression of CD103 on human MoDCs was confirmed by internalization assay. To analyze whether DC-expressed CD103 promotes adhesion to E-cadherin, we performed adhesion and spreading assays on E-cadherin-coated glass slides. In MoDCs generated in the presence of retinoic acid, which express increased CD103, intracellular CD103 significantly redistributed toward the E-cadherin-coated glass surface. However, DCs spreading and adhesion did not differ between E-cadherin-coated slides and slides coated with serum alone. In adhesion assays using E-cadherin-positive HT-29 cells, DC binding was significantly improved by addition of Mn2+ and decreased in the presence of EGTA, consistent with the dependence of integrin-based interactions on divalent cations. However, retinoic acid failed to increase DC adhesion, and a CD103 neutralizing antibody was unable to inhibit DC binding to the E-cadherin positive cells. In contrast, a blocking antibody to DC-expressed E-cadherin significantly reduced DC binding to the epithelium. Overall, these data indicate that CD103 engages in DC-epithelial cell interactions upon contact with epithelial E-cadherin, but is not a major driver of DC adhesion to gastrointestinal epithelia.

Skin Damage in Chronic Venous Insufficiency: Does an Oxygen Diffusion Barrier Really Exist?

Eleven patients with lipodermatosclerosis (LDS) and 14 patients without venous or arterial disease underwent measurement of xenon-133 (133Xe) half-clearance times from the gaiter region of the leg. Xenon has similar diffusion characteristics to oxygen, and the investigation reflects the ability of the isotope to diffuse from the skin surface into capillary blood. Median skin half-clearance time for skin in the LDS group was 2.2 min and in the control group 2.1 min. From the subcutaneous tissues, the respective times were 14.1 and 17.4 minutes. These differences are not statistically significant. The study fails to yield evidence suggesting that an oxygen diffusion barrier exists in lipodermatosclerosis.

Drug Treatment of Chronic Venous Insufficiency and Venous Ulceration: A Review

Treatment of venous insufficiency and venous ulceration has for many years relied on established principles of compression and limb elevation. Drug treatment has been of little benefit. In recent years, a better understanding of the pathological mechanisms underlying skin damage in venous disease has allowed more rational pharmacotherapeutic approaches to be made. This review examines these, with special reference to current theories of the cause of venous ulceration.

Helicobacter pylori infection is associated with an altered gastric microbiota in children

The intestinal microbiome in early life influences development of the mucosal immune system and predisposition to certain diseases. Because less is known about the microbiome in the stomach and its relationship to disease, we characterized the microbiota in the stomachs of 86 children and adults and the impact of Helicobacter pylori infection on the bacterial communities. The overall composition of the gastric microbiota in children and adults without H. pylori infection was similar, with minor differences in only low abundance taxa. However, the gastric microbiota in H. pylori-infected children, but not infected adults, differed significantly in the proportions of multiple high abundance taxa compared with their non-infected peers. The stomachs of H. pylori-infected children also harbored more diverse microbiota, smaller abundance of Firmicutes, and larger abundance of non-Helicobacter Proteobacteria and several lower taxonomic groups than stomachs of H. pylori-infected adults. Children with restructured gastric microbiota had higher levels of FOXP3, IL10, and TGFβ expression, consistent with increased T-regulatory cell responses, compared with non-infected children and H. pylori-infected adults. The gastric commensal bacteria in children are altered during H. pylori infection in parallel with more tolerogenic gastric mucosae, potentially contributing to the reduced gastric disease characteristic of H. pylori-infected children.

Characterization of Human Blood Monocytes and Intestinal Macrophages

Monocytes and macrophages play fundamental roles in defense against microbes, clearance of senescent and dead cells, and immunoregulation. Although blood monocytes are the source of intestinal macrophages in the developed mucosal immune system, blood monocytes and intestinal macrophages from healthy human subjects display distinct phenotypic and functional differences. Blood monocytes can be induced to polarize into M1 and M2 macrophages, whereas intestinal macrophages appear to be terminally differentiated and are unable to undergo such inducible polarization. Nevertheless, in response to local conditions, monocytes differentiated into intestinal macrophages display phenotypic and functional characteristics that enhance their capacity to provide non-inflammatory host defense and participate in local immunoregulation. Using the protocols described here, this unit presents the key phenotypic and functional differences between human blood monocytes and intestinal macrophages, as well as between mouse and human intestinal macrophages. © 2017 by John Wiley & Sons, Inc.

Differential regulation of CD103 (αE integrin) expression in human dendritic cells by retinoic acid and Toll-like receptor ligands

CD103 (αE integrin) is an important dendritic cell (DC) marker that characterizes functionally distinct DC subsets in mice and humans. However, the mechanism by which CD103 expression is regulated in human DCs and the role of CD103 for DC function are not very well understood. Here, we show that retinoic acid (RA) treatment of human monocyte-derived DCs (MoDCs) increased the ability of the DCs to synthesize RA and induced MoDC expression of CD103 and β7 at the mRNA and protein level. In contrast, RA was unable to induce the expression of CD103 in primary human DCs isolated from the gastric mucosa. Inhibition of TGF-β signaling in MoDCs down-regulated RA-induced CD103 expression, indicating that TGF-β-dependent pathways contribute to the induction of CD103. Conversely, when RA-treated MoDCs were stimulated with live Helicobacter pylori, commensal bacteria, LPS, or a TLR2 agonist, the RA-induced up-regulation of CD103 and β7 integrin expression was completely abrogated. To determine whether CD103 expression impacts DC priming of CD4⁺ T cells, we next investigated the ability of CD103⁺ and CD103^─ DCs to induce mucosal homing and T cell proliferation. Surprisingly, RA treatment of DCs enhanced both α4β7 expression and proliferation in cocultured T cells, but no difference was seen between RA-treated CD103⁺ and CD103^─ DCs. In summary, our data demonstrate that RA, bacterial products, and the tissue environment all contribute to the regulation of CD103 on human DCs and that DC induction of mucosal homing in T cells is RA dependent but not CD103 dependent.

Chyle leak following right axillary lymph node dissection: A case report and review of current literature

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Chyle leak is an uncommon complication of axillary node dissection.

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The majority of reported cases occur on the left side, however several instances of right sided chyle leaks are reported.

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The majority of chyle leaks respond to conservative management with: diet modification, pressure and drainage.

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Diagnosis is based on clinical appearance for drainage, laboratory evaluation and lymphscintigraphy.

This report discusses the case of a chyle leak following a right axillary lymph node dissection for breast cancer. This presented as a sudden change in drainage character from a right axillary surgical drain from serous to milky white shortly after restarting a diet. The diagnosis of chyle leak was confirmed by laboratory testing of the fluid and managed with closed suction drainage. Chyle leak is a rare, but increasingly recognized complication following axillary clearance for breast cancer and melanoma.

Mother-to-Child HIV-1 Transmission Events Are Differentially Impacted by Breast Milk and Its Components from HIV-1-Infected Women

Breast milk is a vehicle of infection and source of protection in post-natal mother-to-child HIV-1 transmission (MTCT). Understanding the mechanism by which breast milk limits vertical transmission will provide critical insight into the design of preventive and therapeutic approaches to interrupt HIV-1 mucosal transmission. However, characterization of the inhibitory activity of breast milk in human intestinal mucosa, the portal of entry in postnatal MTCT, has been constrained by the limited availability of primary mucosal target cells and tissues to recapitulate mucosal transmission ex vivo. Here, we characterized the impact of skimmed breast milk, breast milk antibodies (Igs) and non-Ig components from HIV-1-infected Ugandan women on the major events of HIV-1 mucosal transmission using primary human intestinal cells and tissues. HIV-1-specific IgG antibodies and non-Ig components in breast milk inhibited the uptake of Ugandan HIV-1 isolates by primary human intestinal epithelial cells, viral replication in and transport of HIV-1- bearing dendritic cells through the human intestinal mucosa. Breast milk HIV-1-specific IgG and IgA, as well as innate factors, blocked the uptake and transport of HIV-1 through intestinal mucosa. Thus, breast milk components have distinct and complementary effects in reducing HIV-1 uptake, transport through and replication in the intestinal mucosa and, therefore, likely contribute to preventing postnatal HIV-1 transmission. Our data suggests that a successful preventive or therapeutic approach would require multiple immune factors acting at multiple steps in the HIV-1 mucosal transmission process.

Human gastric epithelial cells contribute to gastric immune regulation by providing retinoic acid to dendritic cells

Despite the high prevalence of chronic gastritis caused by Helicobacter pylori, the gastric mucosa has received little investigative attention as a unique immune environment. Here, we analyzed whether retinoic acid (RA), an important homeostatic factor in the small intestinal mucosa, also contributes to gastric immune regulation. We report that human gastric tissue contains high levels of the RA precursor molecule retinol (ROL), and that gastric epithelial cells express both RA biosynthesis genes and RA response genes, indicative of active RA biosynthesis. Moreover, primary gastric epithelial cells cultured in the presence of ROL synthesized RA in vitro and induced RA biosynthesis in co-cultured monocytes through an RA-dependent mechanism, suggesting that gastric epithelial cells may also confer the ability to generate RA on gastric dendritic cells (DCs). Indeed, DCs purified from gastric mucosa had similar levels of aldehyde dehydrogenase activity and RA biosynthesis gene expression as small intestinal DCs, although gastric DCs lacked CD103. In H. pylori-infected gastric mucosa, gastric RA biosynthesis gene expression was severely disrupted, which may lead to reduced RA signaling and thus contribute to disease progression. Collectively, our results support a critical role for RA in human gastric immune regulation.

Gastric microbiome and gastric cancer

Cancer of the stomach is the fourth most common cancer worldwide. The single strongest risk factor for gastric cancer is Helicobacter pylori-associated chronic gastric inflammation. Among persons with H. pylori infection, strain-specific components, host immune responses, and environmental factors influence the risk for gastric disease, including adenocarcinoma of the stomach, although only a small proportion of infected persons develop the malignancy. Recent advances in DNA sequencing technology have uncovered a complex community of noncultivatable inhabitants of the human stomach. The interaction between these inhabitants, collectively referred to as the gastric microbiota, and H. pylori likely affects gastric immunobiology and possibly the sequelae of H. pylori infection. Thus, characterization of the gastric microbiota in subjects with and without H. pylori infection could provide new insight into gastric homeostasis and the pathogenesis of H. pylori-associated disease, including gastric cancer.

Cytomegalovirus enhances macrophage TLR expression and MyD88-mediated signal transduction to potentiate inducible inflammatory responses

Circulating monocytes carrying human CMV (HCMV) migrate into tissues, where they differentiate into HCMV-infected resident macrophages that upon interaction with bacterial products may potentiate tissue inflammation. In this study, we investigated the mechanism by which HCMV promotes macrophage-orchestrated inflammation using a clinical isolate of HCMV (TR) and macrophages derived from primary human monocytes. HCMV infection of the macrophages, which was associated with viral DNA replication, significantly enhanced TNF-α, IL-6, and IL-8 gene expression and protein production in response to TLR4 ligand (LPS) stimulation compared with mock-infected LPS-stimulated macrophages during a 6-d in vitro infection. HCMV infection also potentiated TLR5 ligand-stimulated cytokine production. To elucidate the mechanism by which HCMV infection potentiated inducible macrophage responses, we show that infection by HCMV promoted the maintenance of surface CD14 and TLR4 and TLR5, which declined over time in mock-infected macrophages, and enhanced both the intracellular expression of adaptor protein MyD88 and the inducible phosphorylation of IκBα and NF-κB. These findings provide additional information toward elucidating the mechanism by which HCMV potentiates bacteria-induced NF-κB-mediated macrophage inflammatory responses, thereby enhancing organ inflammation in HCMV-infected tissues.

Differential glycosylation of envelope gp120 is associated with differential recognition of HIV-1 by virus-specific antibodies and cell infection

BACKGROUND

HIV-1 entry into host cells is mediated by interactions between the virus envelope glycoprotein (gp120/gp41) and host-cell receptors. N-glycans represent approximately 50% of the molecular mass of gp120 and serve as potential antigenic determinants and/or as a shield against immune recognition. We previously reported that N-glycosylation of recombinant gp120 varied, depending on the producer cells, and the glycosylation variability affected gp120 recognition by serum antibodies from persons infected with HIV-1 subtype B. However, the impact of gp120 differential glycosylation on recognition by broadly neutralizing monoclonal antibodies or by polyclonal antibodies of individuals infected with other HIV-1 subtypes is unknown.

METHODS

Recombinant multimerizing gp120 antigens were expressed in different cells, HEK 293T, T-cell, rhabdomyosarcoma, hepatocellular carcinoma, and Chinese hamster ovary cell lines. Binding of broadly neutralizing monoclonal antibodies and polyclonal antibodies from sera of subtype A/C HIV-1-infected subjects with individual gp120 glycoforms was assessed by ELISA. In addition, immunodetection was performed using Western and dot blot assays. Recombinant gp120 glycoforms were tested for inhibition of infection of reporter cells by SF162 and YU.2 Env-pseudotyped R5 viruses.

RESULTS

We demonstrated, using ELISA, that gp120 glycans sterically adjacent to the V3 loop only moderately contribute to differential recognition of a short apex motif GPGRA and GPGR by monoclonal antibodies F425 B4e8 and 447-52D, respectively. The binding of antibodies recognizing longer peptide motifs overlapping with GPGR epitope (268 D4, 257 D4, 19b) was significantly altered. Recognition of gp120 glycoforms by monoclonal antibodies specific for other than V3-loop epitopes was significantly affected by cell types used for gp120 expression. These epitopes included CD4-binding site (VRC03, VRC01, b12), discontinuous epitope involving V1/V2 loop with the associated glycans (PG9, PG16), and an epitope including V3-base-, N332 oligomannose-, and surrounding glycans-containing epitope (PGT 121). Moreover, the different gp120 glycoforms variably inhibited HIV-1 infection of reporter cells.

CONCLUSION

Our data support the hypothesis that the glycosylation machinery of different cells shapes gp120 glycosylation and, consequently, impacts envelope recognition by specific antibodies as well as the interaction of HIV-1 gp120 with cellular receptors. These findings underscore the importance of selection of appropriately glycosylated HIV-1 envelope as a vaccine antigen.

Ex vivo lung perfusion allows successful transplantation of donor lungs from hanging victims

BACKGROUND

Donor lungs acquired from victims of asphyxiation by hanging are not routinely used for lung transplantation because of the associated lung injury. Ex vivo lung perfusion (EVLP) is a technique to evaluate marginal donor lungs before transplantation. We report here our experience with the use of EVLP in donor lungs procured from victims of asphyxia by hanging.

METHODS

Lungs from 5 donors who became brain dead secondary to hanging were evaluated by EVLP. Donor organs were perfused according to trial protocol. Donor lungs were accepted for transplantation if they maintained a PaO2 greater than or equal to 350 mm Hg, had a clear roentgenogram, and had no significant worsening of physiologic metrics.

RESULTS

Perfused organs included single and double lung blocs, and all were perfused without technical incident. Three of the 5 donor organs evaluated met criteria for transplantation after 3 hours of EVLP and were transplanted. Donor organs rejected for transplantation showed either signs of worsening PaO2 or deterioration of physiologic metrics. There were no intraoperative complications in the patients who underwent transplantation, and all were alive at 30 days.

CONCLUSIONS

We report here the successful use of EVLP to assess donor lungs acquired from victims of asphyxiation by hanging. The use of EVLP in this particular group of donors has the potential to expand the available donor pool. We demonstrate that EVLP is a viable option for evaluating the function of lung allografts before transplantation and would recommend that all donor lungs obtained from hanging victims undergo EVLP to assess their suitability for transplantation.

Interactions between HIV-1 and mucosal cells in the female reproductive tract

Worldwide, the heterosexual route is the prevalent mode of HIV-1 transmission, and the female reproductive tract accounts for approximately 40% of all HIV-1 transmissions. HIV-1 infection in the female reproductive tract involves three major events: entry through the mucosal epithelium, productive infection in subepithelial mononuclear cells, and delivery to lymph nodes to initiate systemic infection. Here, we provide a focused review of the interaction between HIV-1 and mucosal epithelial cells, lymphocytes, macrophages, and dendritic cells in female genital mucosa. Increased understanding of these interactions could illuminate new approaches for interdicting HIV-1 heterosexual transmission.

Reproducable paraplegia by thoracic aortic occlusion in a murine model of spinal cord ischemia-reperfusion

BACKGROUND

Lower extremity paralysis continues to complicate aortic interventions. The lack of understanding of the underlying pathology has hindered advancements to decrease the occurrence this injury. The current model demonstrates reproducible lower extremity paralysis following thoracic aortic occlusion.

METHODS

Adult male C57BL6 mice were anesthetized with isoflurane. Through a cervicosternal incision the aorta was exposed. The descending thoracic aorta and left subclavian arteries were identified without entrance into pleural space. Skeletonization of these arteries was followed by immediate closure (Sham) or occlusion for 4 min (moderate ischemia) or 8 min (prolonged ischemia). The sternotomy and skin were closed and the mouse was transferred to warming bed for recovery. Following recovery, functional analysis was obtained at 12 hr intervals until 48 hr.

RESULTS

Mice that underwent sham surgery showed no observable hind limb deficit. Mice subjected to moderate ischemia for 4 min had minimal functional deficit at 12 hr followed by progression to complete paralysis at 48 hr. Mice subjected to prolonged ischemia had an immediate paralysis with no observable hind-limb movement at any point in the postoperative period. There was no observed intraoperative or post operative mortality.

CONCLUSION

Reproducible lower extremity paralysis whether immediate or delayed can be achieved in a murine model. Additionally, by using a median sternotomy and careful dissection, high survival rates, and reproducibility can be achieved.

Brain angiogenesis inhibitor 1 is expressed by gastric phagocytes during infection with Helicobacter pylori and mediates the recognition and engulfment of human apoptotic gastric epithelial cells

After Helicobacter pylori infection in humans, gastric epithelial cells (GECs) undergo apoptosis due to stimulation by the bacteria or inflammatory cytokines. In this study, we assessed the expression and function of brain angiogenesis inhibitor 1 (BAI1) in the engulfment of apoptotic GECs using human tissue and cells. After induction of apoptosis by H. pylori or camptothecin, there was a 5-fold increase in the binding of apoptotic GECs to THP-1 cells or peripheral blood monocyte-derived macrophages as assayed by confocal microscopy or conventional and imaging flow cytometry. Binding was impaired 95% by pretreating apoptotic cells with annexin V, underscoring the requirement for phosphatidylserine recognition. The phosphatidylserine receptor BAI1 was expressed in human gastric biopsy specimens and gastric phagocytes. To confirm the role of BAI1 in apoptotic cell clearance, the functional domain of BAI1 was used as a competitive inhibitor or BAI1 expression was inhibited by small interfering RNA. Both approaches decreased binding and engulfment >40%. Exposing THP-1 cells to apoptotic cells inhibited IL-6 production from 1340 to <364 pg/ml; however, this decrease was independent of phagocytosis. We conclude that recognition of apoptotic cells by BAI1 contributes to their clearance in the human gastric mucosa and this is associated with anti-inflammatory effects.

Mucosal correlates of protection in HIV-1-exposed sero-negative persons

Resistance to HIV-1 infection in HIV-1-exposed sero-negative (HESN) persons offers a promising opportunity to identify mechanisms of 'natural' protection. Unique features of the mucosa in particular may contribute to this protection. Here, we highlight several key issues pertaining to the mucosal correlates of protection in HESN persons, including humoral immune responses, mechanisms of mucosal HIV-1 neutralization, immune cell activation, and role of the microbiota in mucosal responses. We also discuss mucosal model systems that can be used to investigate the mechanisms of resistance in HESN subjects. A clear understanding of the mucosal correlates of protection against HIV-1 in HESN persons will provide critical new insights for the development of effective vaccine and microbicide strategies for the prevention of HIV-1 transmission.

Role of childhood infection in the sequelae of H. pylori disease

The persistence of Helicobacter pylori infection plays a fundamental role in the development of H. pylori-associated complications. Since the majority of infected persons acquire the bacteria during early childhood, an examination of the immunobiology of H. pylori infection in children compared with that of adults may help identify host factors that contribute to persistent infection. Therefore, we begin our review of the role of persistence in H. pylori disease with an assessment of the clinical features of H. pylori infection in children. We next review the bacterial factors that promote colonization and evasion of host defense mechanisms. We then focus our attention on the early host immunological factors that promote persistence of the infection and its complications in humans and mouse models. We also highlight topics in which further research is needed. An examination of how immunological factors cause divergent manifestations of H. pylori infection in children compared with adults may provide new insight for therapeutic modification or prevention of persistent H. pylori infection and its complications.

Acute tumour response to the MEK1/2 inhibitor selumetinib (AZD6244, ARRY-142886) evaluated by non-invasive diffusion-weighted MRI

BACKGROUND

Non-invasive imaging biomarkers underpin the development of molecularly targeted anti-cancer drugs. This study evaluates tumour apparent diffusion coefficient (ADC), measured by diffusion-weighted magnetic resonance imaging (DW-MRI), as a biomarker of response to the MEK1/2 inhibitor selumetinib (AZD6244, ARRY-142886) in human tumour xenografts.

METHODS

Nude mice bearing human BRAF(V600D) WM266.4 melanoma or BRAF(V600E) Colo205 colon carcinoma xenografts were treated for 4 days with vehicle or selumetinib. DW-MRI was performed before and 2 h after the last dose and excised tumours analysed for levels of phospho-ERK1/2, cleaved caspase 3 (CC3) and necrosis.

RESULTS

Selumetinib treatment induced tumour stasis and reduced ERK1/2 phosphorylation in both WM266.4 and Colo205 tumour xenografts. Relative to day 0, mean tumour ADC was unchanged in the control groups but was significantly increased by up to 1.6-fold in selumetinib-treated WM266.4 and Colo205 tumours. Histological analysis revealed a significant increase in necrosis in selumetinib-treated WM266.4 and Colo205 xenografts and CC3 staining in selumetinib-treated Colo205 tumours relative to controls.

CONCLUSION

Changes in ADC following treatment with the MEK1/2 inhibitor selumetinib in responsive human tumour xenografts were concomitant with induction of tumour cell death. ADC may provide a useful non-invasive pharmacodynamic biomarker for early clinical assessment of response to selumetinib and other MEK-ERK1/2 signalling-targeted therapies.

Toll-Like Receptor 4–Dependent Microglial Activation Mediates Spinal Cord Ischemia–Reperfusion Injury

Background—

Paraplegia continues to complicate thoracoabdominal aortic interventions. The elusive mechanism of spinal cord ischemia–reperfusion injury has delayed the development of pharmacological adjuncts. Microglia, the resident macrophages of the central nervous system, can have pathological responses after a variety of insults. This can occur through toll-like receptor 4 (TLR-4) in stroke models. We hypothesize that spinal cord ischemia–reperfusion injury after aortic occlusion results from TLR-4–mediated microglial activation in mice.

Methods and Results—

TLR-4 mutant and wild-type mice underwent aortic occlusion for 5 minutes, followed by 60 hours of reperfusion when spinal cords were removed for analysis. Spinal cord cytokine production and microglial activation were assessed at 6 and 36 hours after surgery. Isolated microglia from mutant and wild-type mice were subjected to oxygen and glucose deprivation for 24 hours, after which the expression of TLR-4 and proinflammatory cytokines was analyzed. Mice without functional TLR-4 demonstrated decreased microglial activation and cytokine production and had preserved functional outcomes and neuronal viability after thoracic aortic occlusion. After oxygen and glucose deprivation, wild-type microglia had increased TLR-4 expression and production of proinflammatory cytokines.

Conclusions—

The absence of functional TLR-4 attenuated neuronal injury and microglial activation after thoracic aortic occlusion in mice. Furthermore, microglial upregulation of TLR-4 occurred after oxygen and glucose deprivation, and the absence of functional TLR-4 significantly attenuated the production of proinflammatory cytokines. In conclusion, TLR-4–mediated microglia activation in the spinal cord after aortic occlusion is critical in the mechanism of paraplegia after aortic cross-clamping and may provide targets for pharmacological intervention.

Helicobacter pylori infection inhibits phagocyte clearance of apoptotic gastric epithelial cells

Increased apoptotic death of gastric epithelial cells is a hallmark of Helicobacter pylori infection, and altered epithelial cell turnover is an important contributor to gastric carcinogenesis. To address the fate of apoptotic gastric epithelial cells and their role in H. pylori mucosal disease, we investigated phagocyte clearance of apoptotic gastric epithelial cells in H. pylori infection. Human gastric mononuclear phagocytes were analyzed for their ability to take up apoptotic epithelial cells (AECs) in vivo using immunofluorescence analysis. We then used primary human gastric epithelial cells induced to undergo apoptosis by exposure to live H. pylori to study apoptotic cell uptake by autologous monocyte-derived macrophages. We show that HLA-DR(+) mononuclear phagocytes in human gastric mucosa contain cytokeratin-positive and TUNEL-positive AEC material, indicating that gastric phagocytes are involved in AEC clearance. We further show that H. pylori both increased apoptosis in primary gastric epithelial cells and decreased phagocytosis of the AECs by autologous monocyte-derived macrophages. Reduced macrophage clearance of apoptotic cells was mediated in part by H. pylori-induced macrophage TNF-α, which was expressed at higher levels in H. pylori-infected, compared with uninfected, gastric mucosa. Importantly, we show that H. pylori-infected gastric mucosa contained significantly higher numbers of AECs and higher levels of nonphagocytosed TUNEL-positive apoptotic material, consistent with a defect in apoptotic cell clearance. Thus, as shown in other autoimmune and chronic inflammatory diseases, insufficient phagocyte clearance may contribute to the chronic and self-perpetuating inflammation in human H. pylori infection.

Mechanisms of acquired resistance to ERK1/2 pathway inhibitors

The ERK1/2 (extracellular signal-regulated kinase 1 and 2) pathway, comprising the protein kinases RAF (v-raf-1 murine leukemia viral oncogene homolog 1), MEK1/2 (mitogen-activated protein kinase or ERK kinase 1 and 2) and ERK1/2 is frequently de-regulated in human cancers, due to mutations in RAS or BRAF (v-raf-1 murine leukemia viral oncogene homolog B1). New, highly selective inhibitors of BRAF and MEK1/2 have shown promise in clinical trials, including in previously intractable diseases such as melanoma. However, drug-resistant tumour cells invariably emerge leading to disease progression. It is important to understand the mechanisms underlying such acquired resistance since this may lead to the development of rational strategies either to delay its onset or to overcome it once established. It also offers unique insights into the plasticity of signalling pathways, which may in turn inform our understanding of the basic biology of these pathways and lead to the validation of new drug targets. Several recent reports have identified diverse mechanisms of acquired resistance to MEK1/2 or BRAF inhibitors. In this article, we review these studies, discuss the different mechanisms, identify common themes and consider their therapeutic implications.

Abstract P4-14-09: Feasibility of liposuction for treatment of arm lymphedema from breast cancer

Background: Lymphedema is a dreaded complication of breast cancer treatment affecting 20% of women having axillary node dissection. Liposuction minimizes unwanted fat in targeted areas. Our objective was to explore the feasibility of liposuction to reduce fat volume and thus arm lymphedema.

Methods: An IRB-approved prospective trial was conducted of women having unilateral arm lymphedema resulting from breast cancer treatment. At enrollment there was no evidence of cancer recurrence or arm cellulitis. Arm measurements (circumferential), volumes (water displacement and geometric calculation), and muscle strength differences between the affected and unaffected arms and quality of life/functionality were measured pre-operatively and post-operatively at 6 weeks, 6 months and one year(s). Descriptive statistical analysis was performed.

Results: Six breast cancer survivors underwent the liposuction procedure from 12/2008–4/2011. Median age was 54 yrs (range: 43–60) and median volume of fat aspirated was 700mls (range: 350–700). Average volume difference between the affected and unaffected arms at baseline was 522.5 mls (176–867) (geometric) and 589.2mls (280–770) (water displacement). No immediate complications; 1 cellulitis at 4 months post-operative. Average percent volume reductions for 5 of the 6 women at 6 weeks, 6 months and 1 year were 70%, 47%, 71% mls geometrically and 63%, 18%, 54% by water displacement respectively. Quality of life and functionality improved in all patients. Muscle strength remained unchanged. Pain lessened. Average follow-up is 15.49 months (range: 1.8–24.84 months).

Conclusion: Liposuction can safely reduce volume of arm lymphedema and improve functionality/quality of life. Larger studies (longer follow-up) are required to validate the durability of these early results.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-14-09.

Abstract P4-17-01: The effect of body mass index on breast reconstruction outcomes

Introduction: With increasing numbers of women choosing mastectomy for breast cancer treatment, breast reconstruction is consequentially on the rise. Obesity, a known predictor for wound healing complications, is also on the rise. Our objective is to review our institutional experience with the association between Body Mass Index (BMI) and breast reconstruction complications.

Methods: An IRB approved retrospective review of prospectively gathered patients having mastectomy with reconstruction was conducted. Data including patient demographics, stage at diagnosis, adjuvant treatment, type of mastectomy, type of reconstruction, and complications were collected. Patients were stratified by BMI into two categories: Normal weight (BMI 18.5–24.9), and overweight/obese (BMI 25 or greater). The statistical analysis was preformed using Wilcoxon Rank-Sum Test and Chi Squared Test, both using exact method with Monte Carlo estimation.

Results: From 06/1996 to 08/2011, 443 patients were identified having mastectomy and reconstruction. Of these, 218 patients had a normal weight at the time of mastectomy; 225 patients were overweight/obese. The overall median age was 49 years (range: 18–82). 780 mastectomies with reconstruction (106 unilateral, 337 bilateral) were performed. The most common reconstruction types included 477 tissue expander with implant reconstructions (62.8% of breasts), 106 latissimus flap with prosthesis (14.0%), and 103 pedicled TRAM flaps (13.6%). 245 patients (55.3%) experienced at least one complication; the most common complications were fat necrosis (80 patients, 18.1% of patients), infection (57, 12.9%), epidermolysis (41, 9.3%), and skin necrosis (39, 8.8%).

The overweight/obese group had a significantly higher prevalence of diabetes (6.3% vs. 0.9%, p = 0.0036) and hypertension (26.7% vs. 11.1%, p &lt; 0.0001) and was more likely to receive neoadjuvant chemotherapy (16.2% vs. 4.8% p = 0.0005), possibly due to presentation at a later stage, but no significant differences were identified. Other comorbid conditions, including smoking, history of breast cancer, adjuvant chemotherapy, and history of or postsurgical radiation, were similar between the two groups. One significant difference was that the overweight/obese group was significantly older than the normal weight group (p = 0.0005).

There were no significant differences identified in the incidence of any individual complication between the two BMI groups. Additionally, the incidence of a patient having any complication was similar between the two groups (128 overweight/obese patients for 56.9% and 117 normal weight patients for 53.7%, p = 0.4918). When using breasts instead of patients as the unit of measure, when an overweight/obese patient had a complication they were significantly more likely to require an unanticipated return to the OR (93/160 breasts with a complication for 58.1% vs. 67/154 for 43.5%, p = 0.0124).

Conclusion: Obesity does not increase the risk of breast reconstruction complications, but increases the severity of complications if one should arise. This supports the continued use of breast reconstruction in patients regardless of their weight, and emphasizes that when the correct procedure is selected for an overweight/obese patient, outcomes can be similar to patients that are of a normal weight.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-17-01.

The evolution of chemokine release supports a bimodal mechanism of spinal cord ischemia and reperfusion injury

BACKGROUND

Paraplegia remains a devastating complication of thoracic aortic surgery. The mechanism of the antecedent spinal cord ischemia and reperfusion injury (IR) remains poorly described. IR involves 2 injuries, an initial ischemic insult and subsequent inflammatory amplification of the injury. This mechanism is consistent with the clinical phenomenon of delayed onset paraplegia. This study sought to characterize the inflammatory response in the spinal cord after IR and hypothesized that this would support a bimodal mechanism of injury.

METHODS AND RESULTS

Male C57Bl/6 mice were subjected to 5 minutes of aortic arch and left subclavian occlusion with subsequent reperfusion to generate spinal cord ischemia. Functional outcomes were scored at 12-hour intervals. Spinal cords were harvested after 0, 6, 12, 18, 24, 36, and 48 hours of reperfusion. Cytokine levels were analyzed using a mouse magnetic bead-based multiplex immunoassay. Inflammatory chemokine concentrations (interleukin [IL]-1β, IL-6, keratinocyte-derived cytokine, macrophage inflammatory protein-1α, monocyte chemotactic protein-1, RANTES, and tumor necrosis factor-α) peaked at 6 hours and 36 to 48 hours after reperfusion. Functional scores reflected initial gain in function with subsequent decline, inversely proportional to cytokine levels. Immunofluorescent staining demonstrated microglia activation at 12 and 48 hours.

CONCLUSIONS

Spinal cord ischemia and reperfusion injury occurs in 2 phases, correlating to increases in inflammatory chemokines release and microglial activation. These observations chronologically parallel the too-common clinical syndrome of delayed-onset paraplegia. Understanding the molecular pathogenesis of this injury may allow future intervention to prevent this devastating complication.

Attenuation of spinal cord ischemia-reperfusion injury by specific α-2a receptor activation with dexmedetomidine

BACKGROUND

Despite surgical adjuncts, paralysis remains a devastating complication after thoracoabdominal aortic interventions. Dexmedetomidine, a selective α-2a agonist commonly used for sedation in the critical care setting, has been shown to have protective effects against ischemia-reperfusion injuries in multiple organ systems. We hypothesized that treatment with dexmedetomidine would attenuate spinal cord ischemia-reperfusion injury via α-2a receptor activation.

METHODS

Adult C57BL/6 mice underwent sternotomy, followed by occlusion of the aortic arch for 4 minutes. Eight experimental mice received pretreatment with intraperitoneal dexmedetomidine (25 μg/kg) and at 12-hour intervals after reperfusion. Eight control mice received an equivalent amount of 0.9% normal saline. Five mice underwent the same procedure with dexmedetomidine (25 μg/kg) and atipamezole (250 μg/kg), an α-2a receptor antagonist. Functional analysis of the mice was obtained at 12-hour intervals and scored using the Basso Mouse Scale for Locomotion until 60 hours. All mice were euthanized at 60 hours. Their spinal cords were removed en bloc and were stained with hematoxylin and eosin to assess cytoarchitecture and neuronal viability.

RESULTS

Mice treated with the α-2a agonist demonstrated preserved motor function compared with ischemic controls and with mice treated with the α-2a antagonist in addition to the agonist. Functional differences in the dexmedetomidine group were statistically significant from 24 hours through the remainder of the experiment (P < .05). In addition, the treated mice had preserved cytoarchitecture, decreased vacuolization, and improved neuronal viability compared with ischemic control mice and mice concurrently treated with atipamezole, the dexmedetomidine α-2a antagonist.

CONCLUSIONS

Treatment of mice with the α-2a agonist dexmedetomidine preserves motor function and neuronal viability after aortic cross-clamping. In addition, mice exhibited almost complete reversal of the protective effect with the administration of the α-2a receptor antagonist atipamezole. Dexmedetomidine appears to attenuate spinal cord ischemia-reperfusion injury via α-2a receptor-mediated agonism.

CLINICAL RELEVANCE

There remains a significant risk of paraplegia after thoracoabdominal aortic interventions. This complication is devastating to the patient and the health care system. Pharmacologic adjuncts to further decrease this complication have been studied; however, few viable options exist. The α-2a agonists have been shown to improve outcomes after strokes but have not been studied in spinal cord ischemia. We show that dexmedetomidine, a commonly used α-2a agonist in the operating room, can preserve neurologic function in mice after aortic cross-clamping. Although the protective mechanism of dexmedetomidine remains unknown, it might prove to be beneficial in reducing the incidence of paraplegia after aortic interventions.

Stromal regulation of human gastric dendritic cells restricts the Th1 response to Helicobacter pylori

BACKGROUND & AIMS

Mucosal dendritic cells (DCs) play a key role in initiating the T-helper (Th)1 response to Helicobacter pylori. To further elucidate the mucosal response to H pylori, we examined whether gastric stromal factors condition DCs to support tolerance to H pylori, analogous to intestinal stromal factor-driven macrophage tolerance to commensal bacteria.

METHODS

To model mucosal DC development, we isolated and cultured cell-depleted human stroma/extracellular matrix from fresh gastric and intestinal mucosa to generate stroma-conditioned media. We then analyzed the capacity of stroma-conditioned media-treated monocyte-derived DCs and primary human gastric and intestinal DCs pulsed in vitro with H pylori to induce T-cell proliferation and interferon gamma secretion.

RESULTS

Stromal factors in gastric mucosa suppressed H pylori-stimulated DC activation and the ability of DCs to drive a Th1 proliferative and cytokine response to H pylori. The ability of gastric stromal factors to down-regulate DC function was similar to that of intestinal stromal factors and was independent of transforming growth factor β, prostaglandin E₂, interleukin (IL)-10, and thymic stromal lymphopoietin. Stroma-conditioned media-induced reduction in DC-stimulated Th1 responses was associated with reduced DC release of IL-12.

CONCLUSIONS

Gastric stromal factors down-regulate DC responsiveness to H pylori, resulting in a dampened gastric Th1 response. We speculate that stroma-induced down-regulation of DC function contributes to the permissiveness of both gastric and intestinal mucosa to colonization by persistent residential microbes.

Extracellular matrix-associated cytokines regulate CD4+ effector T-cell responses in the human intestinal mucosa

Extracellular matrix (stroma) regulation of mucosal T-cell function is incompletely understood. In this study, we uncovered a role for intestinal stromal products in the innate regulation of effector T cells. Stroma-conditioned media (S-CM) derived from the normal human intestinal stroma (transforming growth factor-β (TGF-β)(hi)/interleukin (IL)-6(lo)/IL-1β(lo)) significantly downregulated T-cell proliferation and interferon-γ (IFN-γ) production compared with S-CM derived from the inflamed Crohn's mucosa (TGF-β(hi)/IL-6(hi)/IL-1β(hi)). Antibody neutralization studies showed that TGF-β in normal S-CM inhibited T-cell proliferation and IFN-γ production, whereas IL-6 plus IL-1β in Crohn's S-CM promoted T-cell proliferation, and IL-1β alone promoted IFN-γ and IL-17 release. Importantly, normal S-CM inhibited T-bet expression, whereas Crohn's S-CM activated signal transducer and activator of transcription 3, suggesting that discordant T-cell responses are regulated at the transcription factor and signaling levels. These findings implicate stromal TGF-β in the downregulation of T-cell 2 responses in the normal intestinal mucosa, and stromal IL-6 and IL-1β in the promotion of Th1 and Th17 responses in the inflamed Crohn's mucosa, suggesting an innate regulatory function for the intestinal extracellular matrix.

Intestinal macrophages and response to microbial encroachment

Macrophages in the gastrointestinal mucosa represent the largest pool of tissue macrophages in the body. In order to maintain mucosal homeostasis, resident intestinal macrophages uniquely do not express the lipopolysaccharide (LPS) co-receptor CD14 or the IgA (CD89) and IgG (CD16, 32, and 64) receptors, yet prominently display Toll-like receptors (TLRs) 3-9. Remarkably, intestinal macrophages also do not produce proinflammatory cytokines in response to TLR ligands, likely because of extracellular matrix (stromal) transforming growth factor-β (TGF-β) dysregulation of nuclear factor (NF)-κB signal proteins and, via Smad signaling, expression of IκBα, thereby inhibiting NF-κB-mediated activities. Thus, in noninflamed mucosa, resident macrophages are inflammation anergic but retain avid scavenger and host defense function, an ideal profile for macrophages in close proximity to gut microbiota. In the event of impaired epithelial integrity during intestinal infection or inflammation, however, blood monocytes also accumulate in the lamina propria and actively pursue invading microorganisms through uptake and degradation of the organism and release of inflammatory mediators. Consequently, resident intestinal macrophages are inflammation adverse, but when the need arises, they receive assistance from newly recruited circulating monocytes.

Early HIV-1 target cells in human vaginal and ectocervical mucosa

After translocation through the pleuristratified epithelium of the lower female genital tract, HIV-1 encounters potential target mononuclear cells in the lamina propria of the vagina and ectocervix. Here we show that each major type of genital mononuclear cells, including dendritic cells (DCs), macrophages and lymphocytes, are susceptible to HIV-1 in vitro. Among suspensions of vaginal and ectocervical mononuclear cells, DCs were the first cells to take up virus, containing GFP-tagged virions as early as 15 min after exposure. At 2 hr after exposure, DCs still contained the largest proportion of HIV-1(+) cells compared to lamina propria macrophages and lymphocytes from the same mucosal compartment. By 4 days, however, lymphocytes from both vaginal and ectocervical mucosa supported the highest level of HIV-1 replication. Genital macrophages from the same mucosal tissues also were permissive to HIV-1, in sharp contrast to intestinal macrophages, which we have shown previously do not support HIV-1 replication. Thus, among human vaginal and ectocervical mononuclear target cells, DCs are the first to take up HIV-1 and T cells support the most robust viral replication. Further characterization of the parameters of HIV-1 infection in genital mononuclear cells will enhance our understanding of HIV-1 infection in the female genital tract.

Association of red-mark syndrome with a Rickettsia-like organism and its connection with strawberry disease in the USA

Red-mark syndrome (RMS), a disease seen mostly in rainbow trout, Oncorhynchus mykiss, is of unknown aetiology. The research presented here indicates the presence of an intracellular bacterium in RMS-affected fish. A positive reaction was observed using immunohistochemistry (IHC) with skin lesions, liver, kidney and spleen of affected fish sampled from several locations within the United Kingdom using two different polyclonal antisera raised against Piscirickettsia salmonis. The same reaction was also seen with a number of different anti-P. salmonis monoclonal antibodies (MAbs). A disease with similar clinical signs to RMS, referred to as strawberry disease (SD), has been reported in the USA. A Rickettsia-like organism (RLO) has recently been associated with SD based on analysis of 16S rDNA sequences. Using the same panel of anti-P. salmonis antibodies used to screen the RMS samples, similar staining was obtained in tissue of SD-affected fish by IHC. A polymerase chain reaction (PCR) using RLO-specific primers was also performed on RMS-affected fish from the United Kingdom, and the samples were positive for the RLO 16S rRNA sequence. These findings suggest that the same aetiological agent may be responsible for RMS in the United Kingdom and SD in the USA.

Gamma-ray emission concurrent with the nova in the symbiotic binary V407 Cygni

Novae are thermonuclear explosions on a white dwarf surface fueled by mass accreted from a companion star. Current physical models posit that shocked expanding gas from the nova shell can produce x-ray emission, but emission at higher energies has not been widely expected. Here, we report the Fermi Large Area Telescope detection of variable gamma-ray emission (0.1 to 10 billion electron volts) from the recently detected optical nova of the symbiotic star V407 Cygni. We propose that the material of the nova shell interacts with the dense ambient medium of the red giant primary and that particles can be accelerated effectively to produce pi(0) decay gamma-rays from proton-proton interactions. Emission involving inverse Compton scattering of the red giant radiation is also considered and is not ruled out.

Inflammation anergy in human intestinal macrophages is due to Smad-induced IkappaBalpha expression and NF-kappaB inactivation

Human intestinal macrophages contribute to tissue homeostasis in noninflamed mucosa through profound down-regulation of pro-inflammatory cytokine release. Here, we show that this down-regulation extends to Toll-like receptor (TLR)-induced cytokine release, as intestinal macrophages expressed TLR3-TLR9 but did not release cytokines in response to TLR-specific ligands. Likely contributing to this unique functional profile, intestinal macrophages expressed markedly down-regulated adapter proteins MyD88 and Toll interleukin receptor 1 domain-containing adapter-inducing interferon beta, which together mediate all TLR MyD88-dependent and -independent NF-kappaB signaling, did not phosphorylate NF-kappaB p65 or Smad-induced IkappaBalpha, and did not translocate NF-kappaB into the nucleus. Importantly, transforming growth factor-beta released from intestinal extracellular matrix (stroma) induced identical down-regulation in the NF-kappaB signaling and function of blood monocytes, the exclusive source of intestinal macrophages. Our findings implicate stromal transforming growth factor-beta-induced dysregulation of NF-kappaB proteins and Smad signaling in the differentiation of pro-inflammatory blood monocytes into noninflammatory intestinal macrophages.

Glycosylation patterns of HIV-1 gp120 depend on the type of expressing cells and affect antibody recognition

Human immunodeficiency virus type 1 (HIV-1) entry is mediated by the interaction between a variably glycosylated envelope glycoprotein (gp120) and host-cell receptors. Approximately half of the molecular mass of gp120 is contributed by N-glycans, which serve as potential epitopes and may shield gp120 from immune recognition. The role of gp120 glycans in the host immune response to HIV-1 has not been comprehensively studied at the molecular level. We developed a new approach to characterize cell-specific gp120 glycosylation, the regulation of glycosylation, and the effect of variable glycosylation on antibody reactivity. A model oligomeric gp120 was expressed in different cell types, including cell lines that represent host-infected cells or cells used to produce gp120 for vaccination purposes. N-Glycosylation of gp120 varied, depending on the cell type used for its expression and the metabolic manipulation during expression. The resultant glycosylation included changes in the ratio of high-mannose to complex N-glycans, terminal decoration, and branching. Differential glycosylation of gp120 affected envelope recognition by polyclonal antibodies from the sera of HIV-1-infected subjects. These results indicate that gp120 glycans contribute to antibody reactivity and should be considered in HIV-1 vaccine design.

Spectrum of the isotropic diffuse gamma-ray emission derived from first-year Fermi Large Area Telescope data

We report on the first Fermi Large Area Telescope (LAT) measurements of the so-called "extragalactic" diffuse gamma-ray emission (EGB). This component of the diffuse gamma-ray emission is generally considered to have an isotropic or nearly isotropic distribution on the sky with diverse contributions discussed in the literature. The derivation of the EGB is based on detailed modeling of the bright foreground diffuse Galactic gamma-ray emission, the detected LAT sources, and the solar gamma-ray emission. We find the spectrum of the EGB is consistent with a power law with a differential spectral index gamma = 2.41 +/- 0.05 and intensity I(>100 MeV) = (1.03 +/- 0.17) x 10(-5) cm(-2) s(-1) sr(-1), where the error is systematics dominated. Our EGB spectrum is featureless, less intense, and softer than that derived from EGRET data.