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Colorectal cancer surveillance in primary sclerosing cholangitis and inflammatory bowel disease

Thu, 04/14/2016 - 3:49pm

Letter to the editor and case report regarding primary sclerosing cholangitis (PSC), inflammatory bowel disease (IBD), the development of colorectal cancer, cancer screening, and the SCENIC consensus statement on surveillance of colorectal dysplasia.

Size- and shape-dependent foreign body immune response to materials implanted in rodents and non-human primates

Thu, 04/14/2016 - 2:15pm

The efficacy of implanted biomedical devices is often compromised by host recognition and subsequent foreign body responses. Here, we demonstrate the role of the geometry of implanted materials on their biocompatibility in vivo. In rodent and non-human primate animal models, implanted spheres 1.5 mm and above in diameter across a broad spectrum of materials, including hydrogels, ceramics, metals and plastics, significantly abrogated foreign body reactions and fibrosis when compared with smaller spheres. We also show that for encapsulated rat pancreatic islet cells transplanted into streptozotocin-treated diabetic C57BL/6 mice, islets prepared in 1.5-mm alginate capsules were able to restore blood-glucose control for up to 180 days, a period more than five times longer than for transplanted grafts encapsulated within conventionally sized 0.5-mm alginate capsules. Our findings suggest that the in vivo biocompatibility of biomedical devices can be significantly improved simply by tuning their spherical dimensions.

Loss of mTOR signaling affects cone function, cone structure and expression of cone specific proteins without affecting cone survival

Thu, 04/14/2016 - 2:15pm

Cones are the primary photoreceptor (PR) cells responsible for vision in humans. They are metabolically highly active requiring phosphoinositide 3-kinase (PI3K) activity for long-term survival. One of the downstream targets of PI3K is the kinase mammalian target of rapamycin (mTOR), which is a key regulator of cell metabolism and growth, integrating nutrient availability and growth factor signals. Both PI3K and mTOR are part of the insulin/mTOR signaling pathway, however if mTOR is required for long-term PR survival remains unknown. This is of particular interest since deregulation of this pathway in diabetes results in reduced PR function before the onset of any clinical signs of diabetic retinopathy. mTOR is found in two distinct complexes (mTORC1 and mTORC2) that are characterized by their unique accessory proteins RAPTOR and RICTOR respectively. mTORC1 regulates mainly cell metabolism in response to nutrient availability and growth factor signals, while mTORC2 regulates pro-survival mechanisms in response to growth factors. Here we analyze the effect on cones of loss of mTORC1, mTORC2 and simultaneous loss of mTORC1 and mTORC2. Interestingly, neither loss of mTORC1 nor mTORC2 affects cone function or survival at one year of age. However, outer and inner segment morphology is affected upon loss of either complex. In contrast, concurrent loss of mTORC1 and mTORC2 leads to a reduction in cone function without affecting cone viability. The data indicates that PI3K mediated pro-survival signals diverge upstream of both mTOR complexes in cones, suggesting that they are independent of mTOR activity. Furthermore, the data may help explain why PR function is reduced in diabetes, which can lead to deregulation of both mTOR complexes simultaneously. Finally, although mTOR is a key regulator of cell metabolism, and PRs are metabolically highly active, the data suggests that the role of mTOR in regulating the metabolic transcriptome in healthy cones is minimal.

Combined inhibition of Bcl-2/Bcl-xL and Usp9X/Bag3 overcomes apoptotic resistance in glioblastoma in vitro and in vivo

Thu, 04/14/2016 - 2:14pm

Despite great efforts taken to advance therapeutic measures for patients with glioblastoma, the clinical prognosis remains grim. The antiapoptotic Bcl-2 family protein Mcl-1 is overexpressed in glioblastoma and represents an important resistance factor to the BH-3 mimetic ABT263. In this study, we show that combined treatment with ABT263 and GX15-070 overcomes apoptotic resistance in established glioblastoma cell lines, glioma stem-like cells and primary cultures. Moreover, this treatment regimen also proves to be advantageous in vivo. On the molecular level, GX15-070 enhanced apoptosis by posttranslational down-regulation of the deubiquitinase, Usp9X, and the chaperone Bag3, leading to a sustained depletion of Mcl-1 protein levels. Moreover, knock-down of Usp9X or Bag3 depleted endogenous Mcl-1 protein levels and in turn enhanced apoptosis induced through Bcl-2/Bcl-xL inhibition. In conclusion, combined treatment with ABT263 and GX15-070 results in a significantly enhanced anti-cancer activity in vitro as well as in vivo in the setting of glioblastoma. Both drugs, ABT263 and GX15-070 have been evaluated in clinical studies which facilitates the translational aspect of taking this combinatorial approach to the clinical setting. Furthermore we present a novel mechanism by which GX15-070 counteracts Mcl-1 expression which may lay a foundation for a novel target in cancer therapy.

Ablation of retinal ciliopathy protein RPGR results in altered photoreceptor ciliary composition

Thu, 04/14/2016 - 2:14pm

Cilia regulate several developmental and homeostatic pathways that are critical to survival. Sensory cilia of photoreceptors regulate phototransduction cascade for visual processing. Mutations in the ciliary protein RPGR (retinitis pigmentosa GTPase regulator) are a prominent cause of severe blindness disorders due to degeneration of mature photoreceptors. However, precise function of RPGR is still unclear. Here we studied the involvement of RPGR in ciliary trafficking by analyzing the composition of photoreceptor sensory cilia (PSC) in Rpgr(ko) retina. Using tandem mass spectrometry analysis followed by immunoblotting, we detected few alterations in levels of proteins involved in proteasomal function and vesicular trafficking in Rpgr(ko) PSC, prior to onset of degeneration. We also found alterations in the levels of high molecular weight soluble proteins in Rpgr(ko) PSC. Our data indicate RPGR regulates entry or retention of soluble proteins in photoreceptor cilia but spares the trafficking of key structural and phototransduction-associated proteins. Given a frequent occurrence of RPGR mutations in severe photoreceptor degeneration due to ciliary disorders, our results provide insights into pathways resulting in altered mature cilia function in ciliopathies.

Intraflagellar transport 27 is essential for hedgehog signaling but dispensable for ciliogenesis during hair follicle morphogenesis

Thu, 04/14/2016 - 2:14pm

Hair follicle morphogenesis requires precisely controlled reciprocal communications, including hedgehog (Hh) signaling. Activation of the Hh signaling pathway relies on the primary cilium. Disrupting ciliogenesis results in hair follicle morphogenesis defects due to attenuated Hh signaling; however, the loss of cilia makes it impossible to determine whether hair follicle phenotypes in these cilia mutants are caused by the loss of cilia, disruption of Hh signaling, or a combination of these events. In this study, we characterized the function of Ift27, which encodes a subunit of intraflagellar transport (IFT) complex B. Hair follicle morphogenesis of Ift27-null mice was severely impaired, reminiscent of phenotypes observed in cilia and Hh mutants. Furthermore, the Hh signaling pathway was attenuated in Ift27 mutants, which was in association with abnormal ciliary trafficking of SMO and GLI2, and impaired processing of Gli transcription factors; however, formation of the ciliary axoneme was unaffected. The ciliary localization of IFT25 (HSPB11), the binding partner of IFT27, was disrupted in Ift27 mutant cells, and Ift25-null mice displayed hair follicle phenotypes similar to those of Ift27 mutants. These data suggest that Ift27 and Ift25 operate in a genetically and functionally dependent manner during hair follicle morphogenesis. This study suggests that the molecular trafficking machineries underlying ciliogenesis and Hh signaling can be segregated, thereby providing important insights into new avenues of inhibiting Hh signaling, which might be adopted in the development of targeted therapies for Hh-dependent cancers, such as basal cell carcinoma.

Inherited DOCK2 Deficiency in Patients with Early-Onset Invasive Infections

Thu, 04/14/2016 - 2:14pm

Background Combined immunodeficiencies are marked by inborn errors of T-cell immunity in which the T cells that are present are quantitatively or functionally deficient. Impaired humoral immunity is also common. Patients have severe infections, autoimmunity, or both. The specific molecular, cellular, and clinical features of many types of combined immunodeficiencies remain unknown. Methods We performed genetic and cellular immunologic studies involving five unrelated children with early-onset invasive bacterial and viral infections, lymphopenia, and defective T-cell, B-cell, and natural killer (NK)-cell responses. Two patients died early in childhood; after allogeneic hematopoietic stem-cell transplantation, the other three had normalization of T-cell function and clinical improvement. Results We identified biallelic mutations in the dedicator of cytokinesis 2 gene (DOCK2) in these five patients. RAC1 activation was impaired in the T cells. Chemokine-induced migration and actin polymerization were defective in the T cells, B cells, and NK cells. NK-cell degranulation was also affected. Interferon-alpha and interferon-lambda production by peripheral-blood mononuclear cells was diminished after viral infection. Moreover, in DOCK2-deficient fibroblasts, viral replication was increased and virus-induced cell death was enhanced; these conditions were normalized by treatment with interferon alfa-2b or after expression of wild-type DOCK2. Conclusions Autosomal recessive DOCK2 deficiency is a new mendelian disorder with pleiotropic defects of hematopoietic and nonhematopoietic immunity. Children with clinical features of combined immunodeficiencies, especially with early-onset, invasive infections, may have this condition. (Supported by the National Institutes of Health and others.).

Caspase-8 scaffolding function and MLKL regulate NLRP3 inflammasome activation downstream of TLR3

Thu, 04/14/2016 - 2:13pm

TLR2 promotes NLRP3 inflammasome activation via an early MyD88-IRAK1-dependent pathway that provides a priming signal (signal 1) necessary for activation of the inflammasome by a second potassium-depleting signal (signal 2). Here we show that TLR3 binding to dsRNA promotes post-translational inflammasome activation through intermediate and late TRIF/RIPK1/FADD-dependent pathways. Both pathways require the scaffolding but not the catalytic function of caspase-8 or RIPK1. Only the late pathway requires kinase competent RIPK3 and MLKL function. Mechanistically, FADD/caspase-8 scaffolding function provides a post-translational signal 1 in the intermediate pathway, whereas in the late pathway it helps the oligomerization of RIPK3, which together with MLKL provides both signal 1 and 2 for inflammasome assembly. Cytoplasmic dsRNA activates NLRP3 independent of TRIF, RIPK1, RIPK3 or mitochondrial DRP1, but requires FADD/caspase-8 in wildtype macrophages to remove RIPK3 inhibition. Our study provides a comprehensive analysis of pathways that lead to NLRP3 inflammasome activation in response to dsRNA.

Ultrasonography of intrauterine devices

Thu, 04/14/2016 - 2:13pm

The intrauterine device (IUD) is gaining popularity as a reversible form of contraception. Ultrasonography serves as first-line imaging for the evaluation of IUD position in patients with pelvic pain, abnormal bleeding, or absent retrieval strings. This review highlights the imaging of both properly positioned and malpositioned IUDs. The problems associated with malpositioned IUDs include expulsion, displacement, embedment, and perforation. Management considerations depend on the severity of the malposition and the presence or absence of symptoms. Three-dimensional ultrasonography has proven to be more sensitive in the evaluation of more subtle findings of malposition, particularly side-arm embedment. Familiarity with the ultrasonographic features of properly positioned and malpositioned IUDs is essential.

A major role of insulin in promoting obesity-associated adipose tissue inflammation

Thu, 04/14/2016 - 2:12pm

OBJECTIVE: Adipose tissue (AT) inflammation is associated with systemic insulin resistance and hyperinsulinemia in obese rodents and humans. A longstanding concept is that hyperinsulinemia may promote systemic insulin resistance through downregulation of its receptor on target tissues. Here we tested the novel hypothesis that insulin also impairs systemic insulin sensitivity by specifically enhancing adipose inflammation.

METHODS: Circulating insulin levels were reduced by about 50% in diet-induced and genetically obese mice by treatments with diazoxide or streptozotocin, respectively. We then examined AT crown-like structures, macrophage markers and pro-inflammatory cytokine expression in AT. AT lipogenesis and systemic insulin sensitivity was also monitored. Conversely, insulin was infused into lean mice to determine its affects on the above parameters.

RESULTS: Lowering circulating insulin levels in obese mice by streptozotocin treatment decreased macrophage content in AT, enhancing insulin stimulated Akt phosphorylation and de novo lipogenesis (DNL). Moreover, responsiveness of blood glucose levels to injected insulin was improved by streptozotocin and diazoxide treatments of obese mice without changes in body weight. Remarkably, even in lean mice, infusion of insulin under constant euglycemic conditions stimulated expression of cytokines in AT. Consistent with these findings, insulin treatment of 3T3-L1 adipocytes caused a 10-fold increase in CCL2 mRNA levels within 6 h, which was blocked by the ERK inhibitor PD98059.

CONCLUSION: Taken together, these results indicate that obesity-associated hyperinsulinemia unexpectedly drives AT inflammation in obese mice, which in turn contributes to factors that suppress insulin-stimulated adipocyte DNL and systemic insulin sensitivity.

Murine immune responses to virus-like particle-associated pre- and postfusion forms of the respiratory syncytial virus F protein

Thu, 04/14/2016 - 2:12pm

Virus-like particles (VLPs) built on the Newcastle disease virus (NDV) core proteins, NP and M, and containing two chimeric proteins, F/F and H/G, composed of respiratory syncytial virus (RSV) fusion protein (F) and glycoprotein (G) ectodomains fused to the transmembrane and cytoplasmic domains of the NDV F and HN proteins, respectively, stimulate durable, protective RSV neutralizing antibodies in mice. Here, we report the properties of VLPs constructed to contain mutant RSV F protein ectodomains stabilized in prefusion (pre-F/F) or postfusion (post-F/F) configurations. The structures of the chimeric proteins assembled into VLPs were verified immunologically by their reactivities with a conformationally restricted anti-F protein monoclonal antibody. Following immunization of mice, without adjuvant, pre-F/F-containing VLPs induced significantly higher neutralizing antibody titers than the post-F/F-containing VLPs or the wild-type F/F-containing VLPs after a single immunization but not after prime and boost immunization. The specificities of anti-F IgG induced by the two mutant VLPs were assessed by enzyme-linked immunosorbent assay (ELISA) using soluble forms of the prefusion and postfusion forms of the F protein as targets. While both types of VLPs stimulated similar levels of IgG specific for the soluble postfusion F protein, titers of IgG specific for prefusion F induced by the pre-F/F-containing VLPs were higher than those induced by post-F/F-containing VLPs. Thus, VLPs containing a stabilized prefusion form of the RSV F protein represent a promising RSV vaccine candidate.

IMPORTANCE: The development of vaccines for respiratory syncytial virus has been hampered by a lack of understanding of the requirements for eliciting high titers of neutralizing antibodies. The results of this study suggest that particle-associated RSV F protein containing mutations that stabilize the structure in a prefusion conformation may stimulate higher titers of protective antibodies than particles containing F protein in a wild-type or postfusion conformation. These findings indicate that the prefusion F protein assembled into VLPs has the potential to produce a successful RSV vaccine candidate.

Effectiveness of Rituximab for the Treatment of Rheumatoid Arthritis in Patients with Prior Exposure to Anti-TNF: Results from the CORRONA Registry

Thu, 04/14/2016 - 2:12pm

OBJECTIVE: To characterize the real-world effectiveness of rituximab (RTX) in patients with rheumatoid arthritis.

METHODS: Clinical effectiveness at 12 months was assessed in patients who were prescribed RTX based on the Clinical Disease Activity Index (CDAI). Change in CDAI was calculated (CDAI at 12 mos minus at initiation). Achievement of remission or low disease activity (LDA; CDAI < /= 10) among those with moderate/high disease activity at the time of RTX initiation was compared based on prior anti-tumor necrosis factor agent (anti-TNF) use (1 vs > /= 2) using logistic regression models.

RESULTS: Patients (n = 265) were followed for 12 months with a mean change in CDAI of -8.1 (95% CI -9.8 - -6.4). Of the 218 patients with moderate/high disease activity at baseline, patients with 1 prior anti-TNF (baseline CDAI 25.0) demonstrated a mean change in CDAI of -10.1 (95% CI -13.2 - -7.0); patients with > /= 2 prior anti-TNF (baseline CDAI 30.0) demonstrated a mean change of -10.5 (95% CI -12.9 - -8.0). The unadjusted OR for achieving LDA/remission in patients with moderate/high disease activity at baseline exposed to > /= 2 versus 1 prior anti-TNF was 0.40 (95% CI 0.22-0.73), which was robust to 4 different adjusted models (OR range 0.38-0.44).

CONCLUSION: A good clinical response was observed in all patients; however, patients previously treated with 1 anti-TNF, who had lower baseline CDAI and a greater opportunity for clinical improvement compared with patients previously treated with > /= 2 anti-TNF, were more likely to achieve LDA/remission.

Decision Making and the IACUC: Part 1- Protocol Information Discussed at Full-Committee Reviews

Thu, 04/14/2016 - 2:11pm

IACUC protocols can be reviewed by either the full committee or designated members. Both review methods use the principles of the 3 Rs (reduce, refine, replace) as the overarching paradigm, with federal regulations and policies providing more detailed guidance. The primary goal of this study was to determine the frequency of topics discussed by IACUC during full-committee reviews and whether the topics included those required for consideration by IACUC (for example, pain and distress, number of animals used, availability of alternatives, skill and experience of researchers). We recorded and transcribed 87 protocol discussions undergoing full-committee review at 10 academic institutions. Each transcript was coded to capture the key concepts of the discussion and analyzed for the frequency of the codes mentioned. Pain and distress was the code mentioned most often, followed by the specific procedures performed, the study design, and the completeness of the protocol form. Infrequently mentioned topics were alternatives to animal use or painful or distressful procedures, the importance of the research, and preliminary data. Not all of the topics required to be considered by the IACUC were openly discussed for all protocols, and many of the discussions were limited in their depth.

Structural analysis of a novel rabbit monoclonal antibody R53 targeting an epitope in HIV-1 gp120 C4 region critical for receptor and co-receptor binding

Thu, 04/14/2016 - 2:11pm

The fourth conserved region (C4) in the HIV-1 envelope glycoprotein (Env) gp120 is a structural element that is important for its function, as it binds to both the receptor CD4 and the co-receptor CCR5/CXCR4. It has long been known that this region is highly immunogenic and that it harbors B-cell as well as T-cell epitopes. It is the target of a number of antibodies in animal studies, which are called CD4-blockers. However, the mechanism by which the virus shields itself from such antibody responses is not known. Here, we determined the crystal structure of R53 in complex with its epitope peptide using a novel anti-C4 rabbit monoclonal antibody R53. Our data show that although the epitope of R53 covers a highly conserved sequence (433)AMYAPPI(439), it is not available in the gp120 trimer and in the CD4-bound conformation. Our results suggest a masking mechanism to explain how HIV-1 protects this critical region from the human immune system.

alphabeta T cell receptors as predictors of health and disease

Thu, 04/14/2016 - 2:11pm

The diversity of antigen receptors and the specificity it underlies are the hallmarks of the cellular arm of the adaptive immune system. T and B lymphocytes are indeed truly unique in their ability to generate receptors capable of recognizing virtually any pathogen. It has been known for several decades that T lymphocytes recognize short peptides derived from degraded proteins presented by major histocompatibility complex (MHC) molecules at the cell surface. Interaction between peptide-MHC (pMHC) and the T cell receptor (TCR) is central to both thymic selection and peripheral antigen recognition. It is widely assumed that TCR diversity is required, or at least highly desirable, to provide sufficient immune coverage. However, a number of immune responses are associated with the selection of predictable, narrow, or skewed repertoires and public TCR chains. Here, we summarize the current knowledge on the formation of the TCR repertoire and its maintenance in health and disease. We also outline the various molecular mechanisms that govern the composition of the pre-selection, naive and antigen-specific TCR repertoires. Finally, we suggest that with the development of high-throughput sequencing, common TCR 'signatures' raised against specific antigens could provide important diagnostic biomarkers and surrogate predictors of disease onset, progression and outcome.

Breast Reconstruction: Closing the Loop after Breast Cancer

Thu, 04/14/2016 - 2:11pm

Conclusion: As physicians involved at multiple levels in the treatment of breast cancer patients, it is our duty to understand the basics of diagnostic and treatment options for our patients, but also to promote specific counseling about the potential benefits of reconstruction within the medical and general communities. Raising awareness about breast reconstruction enables more women to consider it as an option that for many will translate into an improved quality of life as a breast cancer survivor.

mTORC1 sustains vision in retinitis pigmentosa

Thu, 04/14/2016 - 2:11pm

Introduction: Photoreceptors are highly specialized neurons that have evolved to optimally capture photons. Understanding their demise, in order to develop therapeutic strategies, has the potential to improve the quality of life of millions of patients.

Comparative Genomics Reveals Chd1 as a Determinant of Nucleosome Spacing in Vivo

Thu, 04/14/2016 - 2:10pm

Packaging of genomic DNA into nucleosomes is nearly universally conserved in eukaryotes, and many features of the nucleosome landscape are quite conserved. Nonetheless, quantitative aspects of nucleosome packaging differ between species because, for example, the average length of linker DNA between nucleosomes can differ significantly even between closely related species. We recently showed that the difference in nucleosome spacing between two Hemiascomycete species-Saccharomyces cerevisiae and Kluyveromyces lactis-is established by trans-acting factors rather than being encoded in cis in the DNA sequence. Here, we generated several S. cerevisiae strains in which endogenous copies of candidate nucleosome spacing factors are deleted and replaced with the orthologous factors from K. lactis. We find no change in nucleosome spacing in such strains in which H1 or Isw1 complexes are swapped. In contrast, the K. lactis gene encoding the ATP-dependent remodeler Chd1 was found to direct longer internucleosomal spacing in S. cerevisiae, establishing that this remodeler is partially responsible for the relatively long internucleosomal spacing observed in K. lactis. By analyzing several chimeric proteins, we find that sequence differences that contribute to the spacing activity of this remodeler are dispersed throughout the coding sequence, but that the strongest spacing effect is linked to the understudied N-terminal end of Chd1. Taken together, our data find a role for sequence evolution of a chromatin remodeler in establishing quantitative aspects of the chromatin landscape in a species-specific manner.

The small GTPase Rab8 interacts with VAMP-3 to regulate the delivery of recycling T-cell receptors to the immune synapse

Thu, 04/14/2016 - 2:10pm

IFT20, a component of the intraflagellar transport (IFT) system that controls ciliogenesis, regulates immune synapse assembly in the non-ciliated T-cell by promoting T-cell receptor (TCR) recycling. Here, we have addressed the role of Rab8 (for which there are two isoforms Rab8a and Rab8b), a small GTPase implicated in ciliogenesis, in TCR traffic to the immune synapse. We show that Rab8, which colocalizes with IFT20 in Rab11(+) endosomes, is required for TCR recycling. Interestingly, as opposed to in IFT20-deficient T-cells, TCR(+) endosomes polarized normally beneath the immune synapse membrane in the presence of dominant-negative Rab8, but were unable to undergo the final docking or fusion step. This could be accounted for by the inability of the vesicular (v)-SNARE VAMP-3 to cluster at the immune synapse in the absence of functional Rab8, which is responsible for its recruitment. Of note, and similar to in T-cells, VAMP-3 interacts with Rab8 at the base of the cilium in NIH-3T3 cells, where it regulates ciliary growth and targeting of the protein smoothened. The results identify Rab8 as a new player in vesicular traffic to the immune synapse and provide insight into the pathways co-opted by different cell types for immune synapse assembly and ciliogenesis.

Luciferin Amides Enable in Vivo Bioluminescence Detection of Endogenous Fatty Acid Amide Hydrolase Activity

Thu, 04/14/2016 - 2:10pm

Firefly luciferase is homologous to fatty acyl-CoA synthetases. We hypothesized that the firefly luciferase substrate d-luciferin and its analogs are fatty acid mimics that are ideally suited to probe the chemistry of enzymes that release fatty acid products. Here, we synthesized luciferin amides and found that these molecules are hydrolyzed to substrates for firefly luciferase by the enzyme fatty acid amide hydrolase (FAAH). In the presence of luciferase, these molecules enable highly sensitive and selective bioluminescent detection of FAAH activity in vitro, in live cells, and in vivo. The potency and tissue distribution of FAAH inhibitors can be imaged in live mice, and luciferin amides serve as exemplary reagents for greatly improved bioluminescence imaging in FAAH-expressing tissues such as the brain.