Evaluación del uso de exosomas como aloantígenos para la inducción de tolerancia en trasplante

La consecución de tolerancia aloespecífica es de mucha relevancia en trasplante. Las células dendríticas (DC) son las principales responsables de la inducción de la respuesta inmune frente a las moléculas de histocompatibilidad (MHC) del donante, provocando el rechazo del injerto. Sin embargo las DC son también responsables de la inducción de tolerancia. Diversos modelos animales de alotrasplante han mostrado la tolerización del injerto mediante DC diferenciadas in vitro en condiciones tolerogénicas (tDC). En humanos, las fuentes de aloantígenos potencialmente utilizables en terapia son, entre otras, los cuerpos apoptóticos y los exosomas. Éstos expresan antígenos MHC de forma abundante y su composición es relativamente uniforme, lo que supone una ventaja frente a otras fuentes. En este proyecto, se ha evaluado la obtención de exosomas secretados por una línea de linfocitos T y por células dendríticas derivadas de médula ósea. Se ha caracterizado la captura de exosomas derivados de linfocitos T por células dendríticas humanas derivadas de sangre periférica y su presentación a linfocitos T autólogos. Por otra parte, se ha comenzado a desarrollar los experimentos para estudiar la inducción de tolerancia en un modelo de trasplante renal en rata. Se han generado células dendríticas tolerógenicas derivadas de médula ósea (tolDC), en presencia de dexametasona. Las tolDC expresan menos moléculas de histocompatibilidad y de coestimulación e inducen una menor proliferación en reacciones mixtas leucocitaras, comparadas con las células dendríticas maduras. Por último, se han caracterizado los exosomas de plasma humano con el fin de estudiar su posible uso como aloantígenos. El análisis proteómico revela la presencia de proteínas relacionadas con el sistema inmune, la coagulación, la señalización celular y moléculas implicadas en el transporte y metabolismo de nutrientes. El estudio de la captura por diferentes líneas celulares sugiere que deben existir mecanismos específicos para su internalización.

Inorganic Nanoparticles and the Immune System: Detection, Selective Activation and Tolerance

The immune system is the responsible for body integrity and prevention of external invasion. On one side, nanoparticles are no triggers that the immune system is prepared to detect, on the other side it is known that foreign bodies, not only bacteria, viruses and parasites, but also inorganic matter, can cause various pathologies such as silicosis, asbestosis or inflammatory reactions. Therefore, nanoparticles entering the body, after interaction with proteins, will be either recognized as self-agents or detected by the immune system, encompassing immunostimulation or immunosuppression responses. The nature of these interactions seems to be dictated not specially by the composition of the material but by modifications of NP coating (composition, surface charge and structure). Herein, we explore the use of gold nanoparticles as substrates to carry multifunctional ligands to manipulate the immune system in a controlled manner, from undetection to immunostimulation. Murine bone marrow macrophages can be activated with artificial nanometric objects consisting of a gold nanoparticle functionalized with peptides. In the presence of some conjugates, macrophage proliferation was stopped and pro-inflammatory cytokines were induced. The biochemical type of response depended on the type of conjugated peptide and was correlated with the degree of ordering in the peptide coating. These findings help to illustrate the basic requirements involved in medical NP conjugate design to either activate the immune system or hide from it, in order to reach their targets before being removed by phagocytes. Additionally, it opens up the possibility to modulate the immune response in order to suppress unwanted responses resulting from autoimmunity, or allergy or to stimulate protective responses against pathogens.

Estudi de la resposta immune enfront de Neospora caninum

S’investiga la resposta immune que té lloc en la infecció experimental de les vedelles gestants amb Neospora caninum a les 3, 6 i 9 setmanes postinfecció, amb especial interès en els teixits placentaris. Donada la importancia que tenen les citoquines en la resposta immune a la infecció, s’ha posat a punt les tècniques de RT-PCR a temps real per a l’estudi de l’expressió génica de citoquines del boví. En una fase posterior s’ha estudiat la dinàmica dels anticossos durant l’experiment, la transmissió transplacentària mitjançant l’anàlisi de la presència de DNA parasitari en teixits, la relació entre la producció de IFN-gamma en fluids fetals i, els avortaments i la trasmissió transplacentària i, finalment, el patró de citoquines, amb èmfasi en la interfase materno-fetal.

Association mapping of candidate genes for drought tolerance in Mediterranean durum wheat landraces

Treball al que se li ha concedit el premi al millor póster del congrés

Pathology and immune response of the blue mussel (Mytilus edulis L.) after an exposure to the harmful dinoflagellate Prorocentrum minimum

The harmful dinoflagellate Prorocentrum minimum has different effects upon various species of grazing bivalves, and these effects also vary with life-history stage. Possible effects of this dinoflagellate upon mussels have not been reported; therefore, experiments exposing adult blue mussels, Mytilus edulis, to P. minimum were conducted. Mussels were exposed to cultures of toxic P. minimum or benign Rhodomonas sp. in glass aquaria. After a short period of acclimation, samples were collected on day 0 (before the exposure) and after 3, 6, and 9 days of continuous-exposure experiment. Hemolymph was extracted for flow-cytometric analyses of hemocyte, immune-response functions, and soft tissues were excised for histopathology. Mussels responded to P. minimum exposure with diapedesis of hemocytes into the intestine, presumably to isolate P. minimum cells within the gut, thereby minimizing damage to other tissues. This immune response appeared to have been sustained throughout the 9-day exposure period, as circulating hemocytes retained hematological and functional properties. Bacteria proliferated in the intestines of the P. minimum-exposed mussels. Hemocytes within the intestine appeared to be either overwhelmed by the large number of bacteria or fully occupied in the encapsulating response to P. minimum cells; when hemocytes reached the intestine lumina, they underwent apoptosis and bacterial degradation. This experiment demonstrated that M. edulis is affected by ingestion of toxic P. minimum; however, the specific responses observed in the blue mussel differed from those reported for other bivalve species. This finding highlights the need to study effects of HABs on different bivalve species, rather than inferring that results from one species reflect the exposure responses of all bivalves.

Experimental exposure of the blue mussel (Mytilus edulis, L.) to the toxic dinoflagellate Alexandrium fundyense: Histopathology, immune responses, and recovery

Mussels (Mytilus edulis) were exposed to cultures of the toxic dinoflagellate Alexandrium fundyense or the non-toxic alga Rhodomonas sp. to evaluate the effects of the harmful alga on the mussels and to study recovery after discontinuation of the A. fundyense exposure. Mussels were exposed for 9 days to the different algae and then all were fed Rhodomonas sp. for 6 more days. Samples of hemolymph for hemocyte analyses and tissues for histology were collected before the exposure and periodically during exposure and recovery periods. Mussels filtered and ingested both microalgal cultures, producing fecal pellets containing degraded, partially degraded, and intact cells of both algae. Mussels exposed to A. fundyense had an inflammatory response consisting of degranulation and diapedesis of hemocytes into the alimentary canal and, as the exposure continued, hemocyte migration into the connective tissue between the gonadal follicles. Evidence of lipid peroxidation, similar to the detoxification pathway described for various xenobiotics, was found; insoluble lipofuchsin granules formed (ceroidosis), and hemocytes carried the granules to the alimentary canal, thus eliminating putative dinoflagellate toxins in feces. As the number of circulating hemocytes in A. fundyense-exposed mussels became depleted, mussels were immunocompromised, and pathological changes followed, i.e., increased prevalences of ceroidosis and trematodes after 9 days of exposure. Moreover, the total number of pathological changes increased from the beginning of the exposure until the last day (day 9). After 6 days of the exposure, mussels in one of the three tanks exposed to A. fundyense mass spawned; these mussels showed more severe effects of the toxic algae than non-spawning mussels exposed to A. fundyense. No significant differences were found between the two treatments during the recovery period, indicating rapid homeostatic processes in tissues and circulating hemocytes.

Are Dictators Immune to Human Rights Shaming?

This paper examines whether human rights naming and shaming destabilizes the rule of authoritarian leaders. We argue that human rights shaming can destabilize autocratic leaders by signaling international disapproval to elites in the targeted country, increasing their capacity to replace the incumbent. In personalist regimes, shaming increases the risk of irregular exit because regime elite do not have a means to peacefully replace the incumbent. Shaming campaigns also decrease foreign aid and international trade in personalist regimes, denying the leader access to resources to pay his coalition – further destabilizing his rule. In non-personalist regimes where parties or the military allow elites to peacefully replace incumbents, human rights shaming increases the risk of regular turnover of power, but has little effect on the risk of irregular exit or international flows of aid and trade. These findings have implications for understanding when and where shaming campaigns are likely to reduce or deter repression.

Genome-wide screen of genes required for caffeine tolerance in fission yeast

Background: An excess of caffeine is cytotoxic to all eukaryotic cell types. We aim to study how cells become tolerant to atoxic dose of this drug, and the relationship between caffeine and oxidative stress pathways.Methodology/Principal Findings: We searched for Schizosaccharomyces pombe mutants with inhibited growth on caffeinecontainingplates. We screened a collection of 2,700 haploid mutant cells, of which 98 were sensitive to caffeine. The genes mutated in these sensitive clones were involved in a number of cellular roles including the H2O2-induced Pap1 and Sty1 stress pathways, the integrity and calcineurin pathways, cell morphology and chromatin remodeling. We have investigated the role of the oxidative stress pathways in sensing and promoting survival to caffeine. The Pap1 and the Sty1 pathways are both required for normal tolerance to caffeine, but only the Sty1 pathway is activated by the drug. Cells lacking Pap1 aresensitive to caffeine due to the decreased expression of the efflux pump Hba2. Indeed, ?hba2 cells are sensitive to caffeine, and constitutive activation of the Pap1 pathway enhances resistance to caffeine in an Hba2-dependent manner. Conclusions/Significance: With our caffeine-sensitive, genome-wide screen of an S. pombe deletion collection, we havedemonstrated the importance of some oxidative stress pathway components on wild-type tolerance to the drug.

Modelling the evolution and spread of HIV immune escape mutants.

During infection with human immunodeficiency virus (HIV), immune pressure from cytotoxic T-lymphocytes (CTLs) selects for viral mutants that confer escape from CTL recognition. These escape variants can be transmitted between individuals where, depending upon their cost to viral fitness and the CTL responses made by the recipient, they may revert. The rates of within-host evolution and their concordant impact upon the rate of spread of escape mutants at the population level are uncertain. Here we present a mathematical model of within-host evolution of escape mutants, transmission of these variants between hosts and subsequent reversion in new hosts. The model is an extension of the well-known SI model of disease transmission and includes three further parameters that describe host immunogenetic heterogeneity and rates of within host viral evolution. We use the model to explain why some escape mutants appear to have stable prevalence whilst others are spreading through the population. Further, we use it to compare diverse datasets on CTL escape, highlighting where different sources agree or disagree on within-host evolutionary rates. The several dozen CTL epitopes we survey from HIV-1 gag, RT and nef reveal a relatively sedate rate of evolution with average rates of escape measured in years and reversion in decades. For many epitopes in HIV, occasional rapid within-host evolution is not reflected in fast evolution at the population level.

Empatía y tolerancia a la diversidad en un contexto educativo intercultural = Empathy and tolerance of diversity in an intercultural educative setting

Las relaciones entre empatía y conducta prosocial han estado ampliamente estudiadas desde hace años. Sin embargo, no existen estudios que utilicen estudiantes indígenas y mestizos de una universidad intercultural. El objetivo principal de la investigación fue analizar la tolerancia a la diversidad en relación a la empatía. La muestra estaba formada por 534 indígenas y mestizos, de edades comprendidas entre los 17 y los 22 años. Los resultados mostraron que los estudiantes con una alta capacidad empática eran también más tolerantes. Las chicas puntuaron significativamente superior en tolerancia y empatía que los chicos. Se encuentran diferencias entre indígenas y mestizos y entre universidad intercultural y universidad pública en relación a áreas específicas de la tolerancia a la diversidad

Improving the prediction of the functional impact of cancer mutations by baseline tolerance transformation

High-throughput prioritization of cancer-causing mutations (drivers) is a key challenge of cancer genome projects, due to the number of somatic variants detected in tumors. One important step in this task is to assess the functional impact of tumor somatic mutations. A number of computational methods have been employed for that purpose, although most were originally developed to distinguish disease-related nonsynonymous single nucleotide variants (nsSNVs) from polymorphisms. Our new method, transformed Functional Impact score for Cancer (transFIC), improves the assessment of the functional impact of tumor nsSNVs by taking into account the baseline tolerance of genes to functional variants.

Crucial role of CB(2) cannabinoid receptor in the regulation of central immune responses during neuropathic pain

Neuropathic pain is a clinical manifestation of nerve injury difficult to treat even with potent analgesic compounds. Here, we used different lines of genetically modified mice to clarify the role played by CB2 cannabinoid receptors in the regulation of the central immune responses leading to the development of neuropathic pain. CB2 knock-out mice and wild-type littermates were exposed to sciatic nerve injury, and both genotypes developed a similar hyperalgesia and allodynia in the ipsilateral paw. Most strikingly, knock-outs also developed a contralateral mirror image pain, associated with an enhanced microglial and astrocytic expression in the contralateral spinal horn. In agreement, hyperalgesia, allodynia, and microglial and astrocytic activation induced by sciatic nerve injury were attenuated in transgenic mice overexpressing CB2 receptors. These results demonstrate the crucial role of CB2 cannabinoid receptor in modulating glial activation in response to nerve injury. The enhanced manifestations of neuropathic pain were replicated in irradiated wild-type mice reconstituted with bone marrow cells from CB2 knock-outs, thus demonstrating the implication of the CB2 receptor expressed in hematopoietic cells in the development of neuropathic pain at the spinal cord.

Drought tolerance and light requirements of high and low sublittoral species of Mediterranean macroalgae of the genus Cystoseira C. Agardh (Fucales, Phaeophyceae)

Article sobre la tolerància a la sequera i les necessitats de llum d'espècies de l'alt i baix sublitoral de macroalgues de la Mediterrània del gènere Cystoseira C. Agardh (Fucales, Phaeophyceae)

The Total Deviation Index estimated by Tolerance Intervals to evaluate the concordance of measurement devices

Background In an agreement assay, it is of interest to evaluate the degree of agreement between the different methods (devices, instruments or observers) used to measure the same characteristic. We propose in this study a technical simplification for inference about the total deviation index (TDI) estimate to assess agreement between two devices of normally-distributed measurements and describe its utility to evaluate inter- and intra-rater agreement if more than one reading per subject is available for each device. Methods We propose to estimate the TDI by constructing a probability interval of the difference in paired measurements between devices, and thereafter, we derive a tolerance interval (TI) procedure as a natural way to make inferences about probability limit estimates. We also describe how the proposed method can be used to compute bounds of the coverage probability. Results The approach is illustrated in a real case example where the agreement between two instruments, a handle mercury sphygmomanometer device and an OMRON 711 automatic device, is assessed in a sample of 384 subjects where measures of systolic blood pressure were taken twice by each device. A simulation study procedure is implemented to evaluate and compare the accuracy of the approach to two already established methods, showing that the TI approximation produces accurate empirical confidence levels which are reasonably close to the nominal confidence level. Conclusions The method proposed is straightforward since the TDI estimate is derived directly from a probability interval of a normally-distributed variable in its original scale, without further transformations. Thereafter, a natural way of making inferences about this estimate is to derive the appropriate TI. Constructions of TI based on normal populations are implemented in most standard statistical packages, thus making it simpler for any practitioner to implement our proposal to assess agreement.