Identification of Tumor Antigens in the HLA Peptidome of Patient-derived Xenograft Tumors in Mouse

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Highlights

• •Sufficient tumor tissues are often unavailable large HLA peptidome discovery.
• •Using patient derived xenograft (PDX) tumors can overcome this limitation.
• •The large PDX HLA peptidomes expand significantly those of the original biopsies.
• •The HLA peptidomes of the PDX tumors included many tumor antigens.

     

Serological detection of H-2K- and H-2D-gene products

Using the fluorescence-activated cell sorter (FACS II), we have analyzed the expression of H-2K- and H-2D-gene products on the membrane of various cellular components of the murine immune system. Using this serological technique we show a basic difference between T and B lymphocytes. Whereas all cellular components analyzed — hydrocortisone-resistant thymocytes, splenic T and B lymphocytes, macrophages and bone-marrow cells — expressed H-2K-subregion-encoded alloantigens at a high density, it seems that the high density expression of H-2D-encoded alloantigens is restricted mainly to B cells and to macrophages. Hydrocortisone-resistant thymocytes, splenic T lymphocytes and bone-marrow cells, on the other hand, showed significant expression of the H-2D alloantigens only at low membrane density. These results, then, provide evidence for the existence of an imbalance in serologically detectable expression of H-2K- and H-2D-region-gene products on the cell membrane of various cells comprising the murine immune system.Abbreviations usedin this paper DTH delayed type hypersensitivity - FCS fetal calf serum - FITC fluorescein isothiocyanate - HrT hydrocortisone-resistant thymocytes - Ig immunoglobulins P. De Baetselier is an EMBO and Euratom postdoctoral fellow     

Novel Rickettsiella Bacterium in the Leafhopper Orosius albicinctus (Hemiptera: Cicadellidae)

Bacteria in the genus Rickettsiella (Coxiellaceae), which are mainly known as arthropod pathogens, are emerging as excellent models to study transitions between mutualism and pathogenicity. The current report characterizes a novel Rickettsiella found in the leafhopper Orosius albicinctus (Hemiptera: Cicadellidae), a major vector of phytoplasma diseases in Europe and Asia. Denaturing gradient gel electrophoresis (DGGE) and pyrosequencing were used to survey the main symbionts of O. albicinctus, revealing the obligate symbionts Sulcia and Nasuia, and the facultative symbionts Arsenophonus and Wolbachia, in addition to Rickettsiella. The leafhopper Rickettsiella is allied with bacteria found in ticks. Screening O. albicinctus from the field showed that Rickettsiella is highly prevalent, with over 60% of individuals infected. A stable Rickettsiella infection was maintained in a leafhopper laboratory colony for at least 10 generations, and fluorescence microscopy localized bacteria to accessory glands of the female reproductive tract, suggesting that the bacterium is vertically transmitted. Future studies will be needed to examine how Rickettsiella affects host fitess and its ability to vector phytopathogens.     

Hyperforin inhibits vesicular uptake of monoamines by dissipating pH gradient across synaptic vesicle membrane

Extracts of Hypericum perforatum (St. John's wort) have antidepressant properties in depressed patients and exert antidepressant-like action in laboratory animals. The phloroglucinol derivative hyperforin has become a topic of interest, as this Hypericum component is a potent inhibitor of monoamines reuptake. The molecular mechanism by which hyperforin inhibits monoamines uptake is yet unclear. In the present study we try to clarify the mechanism by which hyperforin inhibits the synaptic vesicle transport of monoamines. The pH gradient across the synaptic vesicle membrane, induced by vacuolar type H(+)-ATPase, is the major driving force for vesicular monoamines uptake and storage. We suggest that hyperforin, like the protonophore FCCP, dissipates an existing Delta pH generated by an efflux of inwardly pumped protons. Proton transport was measured by acridine orange fluorescence quenching. Adding Mg-ATP to a medium containing 130 mM KCl and synaptic vesicles caused an immediate decrease in fluorescence of acridine orange and the addition of 1 microM FCCP abolished this effect. H(+)-ATPase dependent proton pumping was inhibited by hyperforin in a dose dependent manner (IC(50) = 1.9 x 10(-7) M). Hyperforin acted similarly to the protonophore FCCP, abolishing the ATP induced fluorescence quenching (IC(50) = 4.3 x 10(-7) M). Hyperforin and FCCP had similar potencies for inhibiting rat brain synaptosomal uptake of [3H]monoamines as well as vesicular monoamine uptake. The efflux of [3H]5HT from synaptic vesicles was sensitive to both drugs, thus 50% of preloaded [3H]5HT was released in the presence of 2.1 x 10(-7) M FCCP and 4 x 10(-7) M hyperforin. The effect of hyperforin on the pH gradient in synaptic vesicle membrane may explain its inhibitory effect on monoamines uptake, but could only partially explain its antidepressant properties.     

Different patterns of interleukin-1alpha and interleukin-1beta expression in organs of normal young and old mice

The different physiological roles of interleukin-1alpha (IL-1alpha) and interleukin-1beta (IL-1beta) are not well understood, especially when considering the apparent overlap and redundancy of the two IL-1 molecules. Characterization of IL-1alpha and IL-1beta expression was performed in this study in organs from young and old mice, using immunohistochemistry and ELISA (enzyme-linked immunosorbent assay). The results indicate that organ IL-1alpha and IL-1beta display different patterns of expression: IL-1alpha is manifested more prominently in lymphoreticular organs (lungs, small intestine, spleen, liver), while IL-1beta is more evident in highly specialized and more vulnerable organs, which do not play a leading role in defense against infections and intoxication (heart, brain, skeletal muscle, kidney). This differential expression is more accentuated in old mice, possibly pointing to the special relevance of these cytokines to organ homeostasis in old age. These findings may shed new light on the physiological functions of IL-1alpha and IL-1beta, and may also lead to the development of improved therapeutic approaches, based on the specific manipulation of these cytokines.     

Chickens fed with biomass of the red microalga Porphyridium sp. have reduced blood cholesterol level and modified fatty acid composition in egg yolk

The biomass of the red alga Porphyridium sp.constitutes a unique combination of soluble sulfatedpolysaccharide that accounts for about 70% of thealgal dry weight, and various polyunsaturatedfatty acids (PUFA) such as arachidonic andeicosapentaenoic acid (AA, 20:4 6 and EPA,20:5 3). In view of earlier results in ourlaboratory showing a reduction in serum cholesteroland triglyceride levels in rodents fed with red algalbiomass, we set out to examine the influence of algalbiomass as a feed additive on the metabolism ofchickens, with an emphasis on blood and eggcholesterol levels. For that purpose, lyophilizedalgal biomass was fed to 12–13, 30-week-old, WhiteLeghorn chickens for 10 days at a proportion of 5% or10% of the standard chicken diet. Twelve chickensfed with unsupplemented diet served as the control. No differences in body weight, egg number, and eggweight were found between the algal-fed chickens (atboth concentrations) and the control. However,chickens fed with algal biomass consumed 10% lessfood for both groups, and their serum cholesterollevels were significantly lower (by 11% and 28% forthe groups fed with 5% and 10% supplement,respectively) as compared with the respective valuesof the control group. Egg yolk of chickens fed withalgae tended to have reduced cholesterol levels (by10%) and increased linoleic acid and arachidonic acidlevels (by 29% and 24%, respectively). In addition,the color of the egg yolk was darker as a result ofthe higher carotenoid levels (2.4 fold higher) forchickens that fed with 5% supplement. Theseresults encourage the development of an improvedchicken feed having dietary fibers and polyunsaturatedfatty acids.     

Decoding Diffusivity in Multiple Sclerosis: Analysis of Optic Radiation Lesional and Non-Lesional White Matter

Objectives

Diffusion tensor imaging (DTI) has been suggested as a new promising tool in MS that may provide greater pathological specificity than conventional MRI, helping, therefore, to elucidate disease pathogenesis and monitor therapeutic efficacy. However, the pathological substrates that underpin alterations in brain tissue diffusivity are not yet fully delineated. Tract-specific DTI analysis has previously been proposed in an attempt to alleviate this problem. Here, we extended this approach by segmenting a single tract into areas bound by seemingly similar pathological processes, which may better delineate the potential association between DTI metrics and underlying tissue damage.

Method

Several compartments were segmented in optic radiation (OR) of 50 relapsing-remitting MS patients including T2 lesions, proximal and distal parts of fibers transected by lesion and fibers with no discernable pathology throughout the entire length of the OR.

Results

Asymmetry analysis between lesional and non-lesional fibers demonstrated a marked increase in Radial Diffusivity (RD), which was topographically limited to focal T2 lesions and potentially relates to the lesional myelin loss. A relative elevation of Axial Diffusivity (AD) in the distal part of the lesional fibers was observed in a distribution consistent with Wallerian degeneration, while diffusivity in the proximal portion of transected axons remained normal. A moderate, but significant elevation of RD in OR non-lesional fibers was strongly associated with the global (but not local) T2 lesion burden and is probably related to microscopic demyelination undetected by conventional MRI.

Conclusion

This study highlights the utility of the compartmentalization approach in elucidating the pathological substrates of diffusivity and demonstrates the presence of tissue-specific patterns of altered diffusivity in MS, providing further evidence that DTI is a sensitive marker of tissue damage in both lesions and NAWM. Our results suggest that, at least within the OR, parallel and perpendicular diffusivities are affected by tissue restructuring related to distinct pathological processes.     

Real time computation: zooming in on population codes

Information processing in nervous systems intricately combines computation at the neuronal and network levels. Many computations may be envisioned as sequences of signal processing steps along some pathway. How can information encoded by single cells be mapped onto network population codes, and how do different modules or layers in the computation synchronize their communication and computation? These fundamental questions are particularly severe when dealing with real time streams of inputs. Here we study this problem within the context of a minimal signal perception task. In particular, we encode neuronal information by externally applying a space- and time-localized stimulus to individual neurons within a network. We show that a pulse-coupled recurrent neural network can successfully handle this task in real time, and obeys three key requirements: (i) stimulus dependence, (ii) initial-conditions independence, and (iii) accessibility by a readout mechanism. In particular, we suggest that the network's overall level of activity can be used as a temporal cue for a robust readout mechanism. Within this framework, the network can rapidly map a local stimulus onto a population code that can then be reliably read out during some narrow but well defined window of time.