Malaise du nourrisson pensez à une intoxication à l'anis étoil [Apparent life-threatening event in infants: think about star anise intoxication!].

In previous years, several publications have reported cases of infants presenting neurological and gastrointestinal symptoms after ingestion of star anise tea. Such teas are sometimes given in various cultures for the treatment of infant colic pains. In most cases, the cause of intoxication was contamination of Chinese star anise (Illicium verum) by Japanese star anise (Illicium anisatum). Indeed, the toxicity of Illicium anisatum, also known as Shikimi, is caused by its content in potent neurotoxins (anisatin, neoanisatin, and pseudoanisatin), due to their activity as non-competitive antagonists of GABA receptors. The main reasons explaining the frequent contaminations are the strong macroscopic resemblance of the 2 substances, as well as the fact that the fruits are often sold partially broken or in ground form. Therefore, in most cases, chemical analysis is required to determine the possible adulterations. CASE REPORT: A 2-month-old infant, in good general health, was brought to the emergency unit after 3 consecutive episodes of central cyanosis and tetany of the limbs with spontaneous recovery the same afternoon. The child was also very irritable, regurgitated a lot, and positioned himself in opisthotonos. Between these episodes, the neurological exam showed some perturbations (horizontal nystagmus and Bell's phenomenon, hypertony of the extensor muscles, and mild hypotony of the axial flexor muscles) with slow improvement over the following hours. The remaining clinical exam, the laboratory work (complete blood count, renal, hepatic, and muscular tests, capillary blood gas, plasmatic amino acids, and urinary organic acids), and the electroencephalogram findings were all normal. In the course of a detailed interview, the parents reported having given 3 bottles to their child, each one containing 200 mL of an infusion with 4 to 5 fruits of star anise, in the hours preceding the symptoms to relieve colic pains. The last seizure-like event took place approximately 8h after the last ingestion. We could prove the ingestion of anisatin, the toxic substance found in Japanese star anise, and the contamination of Chinese star anise by the Japanese species. Indeed, the anisatin analysis by liquid chromatography and mass spectroscopy (LC-MS) in a urine sample taken 22 h after the last infusion ingestion showed trace amounts of the substance. In another urine sample taken 33 h after ingestion, no anisatin could be detected. Furthermore, the analysis of the fruit sample gave an anisatin concentration of 7800 μg/kg while the maximum tolerance value in Switzerland is 1000 μg/kg. CONCLUSION: The evaluation of ALTE in infants should always include the possibility of intoxication. Star anise is generally considered a harmless medicine. Nevertheless, it can sometimes cause a severe intoxication resulting in various neurological and gastrointestinal symptoms. To prevent such events, not only the parents, but also the care personnel and pharmacists must be informed about the possible adverse effects caused either by the overdose of Chinese star anise or by the eventual contamination of herbal teas with Japanese star anise. A better control of the substances by the health authorities is also necessary.

Cilengitide: an integrin-targeting arginine-glycine-aspartic acid peptide with promising activity for glioblastoma multiforme.

BACKGROUND: Glioblastoma multiforme (GBM), a highly invasive and vascular cancer, responds poorly to conventional cytotoxic therapy. Integrins, widely expressed in GBM and tumor vasculature, mediate cell survival, migration and angiogenesis. Cilengitide is a potent alphavbeta3 and alphavbeta5 integrin inhibitor. OBJECTIVE: To summarize the preclinical and clinical experience with cilengitide for GBM. METHODS: Preclinical studies and clinical trials evaluating cilengitide for GBM were reviewed. RESULTS/CONCLUSIONS: Cilengitide is active and synergizes with external beam radiotherapy in preclinical GBM models. In clinical trials for recurrent GBM, single-agent cilengitide has antitumor benefits and minimal toxicity. Among newly diagnosed GBM patients, single-arm studies incorporating cilengitide into standard external beam radiotherapy/temozolomide have shown encouraging activity with no increased toxicity and have led to a planned randomized Phase III trial.

From the Cover: Nanoparticle conjugation of antigen enhances cytotoxic T-cell responses in pulmonary vaccination.

The ability of vaccines to induce memory cytotoxic T-cell responses in the lung is crucial in stemming and treating pulmonary diseases caused by viruses and bacteria. However, most approaches to subunit vaccines produce primarily humoral and only to a lesser extent cellular immune responses. We developed a nanoparticle (NP)-based carrier that, upon delivery to the lung, specifically targets pulmonary dendritic cells, thus enhancing antigen uptake and transport to the draining lymph node; antigen coupling via a disulfide link promotes highly efficient cross-presentation after uptake, inducing potent protective mucosal and systemic CD8(+) T-cell immunity. Pulmonary immunization with NP-conjugated ovalbumin (NP-ova) with CpG induced a threefold enhancement of splenic antigen-specific CD8(+) T cells displaying increased CD107a expression and IFN-γ production compared with immunization with soluble (i.e., unconjugated) ova with CpG. This enhanced response was accompanied by a potent Th17 cytokine profile in CD4(+) T cells. After 50 d, NP-ova and CpG also led to substantial enhancements in memory CD8(+) T-cell effector functions. Importantly, pulmonary vaccination with NP-ova and CpG induced as much as 10-fold increased frequencies of antigen-specific effector CD8(+) T cells to the lung and completely protected mice from morbidity following influenza-ova infection. Here, we highlight recruitment to the lung of a long-lasting pool of protective effector memory cytotoxic T-cells by our disulfide-linked antigen-conjugated NP formulation. These results suggest the reduction-reversible NP system is a highly promising platform for vaccines specifically targeting intracellular pathogens infecting the lung.

A soluble hexameric form of CD40 ligand activates human dendritic cells and augments memory T cell response.

A strategy to improve the immunogenicity of candidate vaccines is to trigger the innate immune system. Triggering of CD40 at the surface of dendritic cells (DC) is essential in the induction of an efficient immune response. Although CD40 agonist antibodies have been shown to be potent inducers of immune responses in experimental models, serious safety concerns have been raised for their use in humans. In addition, the production of soluble functional CD40 ligand has been challenging and the soluble form existing so far is not developed anymore. Here, we have evaluated the potency of a new soluble form of hexameric CD40 ligand (sCD40L) to serve as an adjuvant for anti-viral T cell responses. sCD40L was able to activate human DC and to enhance virus-specific memory T cell responses. These results demonstrate that this soluble form of CD40 ligand may serve as an adjuvant for T cell response and thus provide the rationale for its potential use in T cell based vaccine strategies.

Angiotensin II is an endogenous neurotransmitter for rat and human mesenteric resistance blood vessels

Angiotensin II (Ang II) is one of the most potent vasoconstrictors. We document here the innervation of rat and human mesenteric resistance arteries (MRA) by angiotensinergic neurons of the rat and human sympathetic coeliac ganglia. Angiotensinogen (Ang-N)-mRNA and angiotensin converting enzyme-mRNA but no renin-mRNA were detected by using quantitative real time polymerase chain reaction in total RNA extracts of rat coeliac ganglia. In the same extracts, cathepsin D-mRNA was detected: This protease also cleaves Ang I from Ang-N and could therefore account for the generation of neuronal Ang peptides in the absence of renin. In situ hybridization confirmed the presence of Ang-N-mRNA in the cytoplasm of rat coeliac ganglia. By using solid-phase extraction, high performance liquid chromatography and subsequent radioimmunoassay, Ang II and its metabolites were detected in rat and also in human coeliac ganglia. Immunoreactivity for Ang II was demonstrated in rat and human coeliac ganglia neurons and their projections innervating MRA. In addition, segmental angiotensinergic innervation of MRA was also observed. By means of confocal laser scanning microscopy we were able to demonstrate the presence of angiotensinergic synapses en passant along side of vascular smooth muscle cells. Our findings could indicate that Ang II is synthesized inside the neurons of sympathetic coeliac ganglia and may act as an endogenous neurotransmitter locally in MRA.

Local delivery of glial cell line-derived neurotrophic factor improves facial nerve regeneration after late repair.

OBJECTIVES/HYPOTHESIS: Facial nerve regeneration is limited in some clinical situations: in long grafts, by aged patients, and when the delay between nerve lesion and repair is prolonged. This deficient regeneration is due to the limited number of regenerating nerve fibers, their immaturity and the unresponsiveness of Schwann cells after a long period of denervation. This study proposes to apply glial cell line-derived neurotrophic factor (GDNF) on facial nerve grafts via nerve guidance channels to improve the regeneration. METHODS: Two situations were evaluated: immediate and delayed grafts (repair 7 months after the lesion). Each group contained three subgroups: a) graft without channel, b) graft with a channel without neurotrophic factor; and c) graft with a GDNF-releasing channel. A functional analysis was performed with clinical observation of facial nerve function, and nerve conduction study at 6 weeks. Histological analysis was performed with the count of number of myelinated fibers within the graft, and distally to the graft. Central evaluation was assessed with Fluoro-Ruby retrograde labeling and Nissl staining. RESULTS: This study showed that GDNF allowed an increase in the number and the maturation of nerve fibers, as well as the number of retrogradely labeled neurons in delayed anastomoses. On the contrary, after immediate repair, the regenerated nerves in the presence of GDNF showed inferior results compared to the other groups. CONCLUSIONS: GDNF is a potent neurotrophic factor to improve facial nerve regeneration in grafts performed several months after the nerve lesion. However, GDNF should not be used for immediate repair, as it possibly inhibits the nerve regeneration.

Strong reciprocity or strong ferocity? A population genetic view of the evolution of altruistic punishment.

Strong reciprocity, defined as a predisposition to help others and to punish those that are not helping, has been proposed as a potent force leading to the evolution of cooperation and altruism. However, the conditions under which strong reciprocity might be favored are not clear. Here we investigate the selective pressure on strong reciprocity by letting both limited dispersal (i.e., spatial structure) and recombination between helping and punishment jointly determine the evolutionary dynamics of strong reciprocity. Our analytical model suggests that when helping and punishment are perfectly linked traits (no recombination occurring between them), strong reciprocity can spread even when the initial frequency of strong reciprocators is close to 0 in the population (i.e., a rare mutant can invade). By contrast, our results indicate that when recombination can occur between helping and punishment (i.e., both traits coevolve) and is stronger than selection, punishment is likely to invade a population of defectors only when it gives a direct fitness benefit to the actor. Overall, our results delineate the conditions under which strong reciprocity is selected for in a spatially structured population and highlight that the forces behind its evolution involves kinship (be it genetic or cultural).

Genetic investigation of the functions of c-Myc and N-Myc in Hematopoietic stem cells

Résumé : c-Myc, le premier facteur de transcription de la famille Myc a été découvert il y a maintenant trente ans. Il reste à l'heure actuelle parmi les plus puissants proto-oncogènes connus. c-Myc est dérégulé dans plus de 50% des cancers, où il promeut la prolifération, la croissance cellulaire, et la néoangiogenèse. Myc peut aussi influencer de nombreuses autres fonctions de par sa capacité à activer ou à réprimer la transcription de nombreux gènes, et à agir globalement sur le génome à travers des modifications épigénétiques de la chromatine. La famille d'oncogènes Myc comprend, chez les mammifères, trois protéines structurellement proches: c-Myc, N-Myc et L-Myc. Ces protéines ont les mêmes proprietés biochimiques, exercent les mêmes fonctions mais sont le plus souvent exprimées de façon mutuellement exclusive. Myc a été récemment identifié comme un facteur clef dans la maintenance des cellules souches embryonnaires et adultes ainsi que dans la réacquisition des proprietés des cellules souches. Nous avons précédemment démontré que l'élimination de c-Myc provoque une accumulation de cellules souches hématopoïétiques (CSH) suite à un défaut de différenciation lié à la niche. Les CSH sont responsables de la production de tous les éléments cellulaires du sang pour toute la vie de l'individu et sont définies par leur capacité à s'auto-renouveler tout en produisant des précurseurs hématopoïétiques. Afin de mieux comprendre la fonction de Myc dans les CSH, nous avons choisi de combiner l'utilisation de modèles de souris génétiquement modifiées à une caractérisation systématique des schémas d'expression de c-Myc, N-Myc et L-Myc dans tout le système hématopoïétique. Nous avons ainsi découvert que les CSH les plus immatures expriment des quantités équivalentes de transcrits de c-myc et N-myc. Si les CSH déficientes en N-myc seulement ont une capacité d'auto-renouvellement à long-terme réduite, l'invalidation combinée des gènes c-myc et N-myc conduit à une pan-cytopénie suivie d'une mort rapide de l'animal, pour cause d'apoptose de tous les types cellulaires hématopoïétiques. En particulier, les CSH en cours d'auto-renouvelemment, mais pas les CSH quiescentes, accumulent du Granzyme B (GrB), une molécule fortement cytotoxique qui provoque une mort cellulaire rapide. Ces données ont ainsi mis au jour un nouveau mécanisme dont dépend la survie des CSH, à savoir la répression du GrB, une enzyme typiquement utilisée par le système immunitaire inné pour éliminer les tumeurs et les cellules infectées par des virus. Dans le but d'évaluer l'étendue de la redondance entre c-Myc et N-Myc dans les CSH, nous avons d'une part examiné des souris dans lesquelles les séquences codantes de c-myc sont remplacées par celles de N-myc (NCR) et d'autre part nous avons géneré une série allèlique de myc en éliminant de façon combinatoire un ou plusieurs allèles de c-myc et/ou de N-myc. Alors que l'analyse des souris NCR suggère que c-Myc et N-Myc sont qualitativement redondants, la série allélique indique que les efficiences avec lesquelles ces deux protéines influencent des procédés essentiels à la maintenance des CSH sont différentes. En conclusion, nos données génétiques montrent que l'activité générale de MYC, fournie par c-Myc et N-Myc, contrôle plusieurs aspects cruciaux de la fonction des CSH, notamment l'auto-renouvellement, la survie et la différenciation. Abstract : c-Myc, the first Myc transcription factor was discovered 30 years ago and is to date one of the most potent proto-oncogenes described. It is found to be misregulated in over 50% of all cancers, where it drives proliferation, cell growth and neo-angiogenesis. Myc can also influence a variety of other functions, owing to its ability to activate and repress transcription of many target genes and to globally regulate the genome via epigenetic modifications of the chromatin. The Myc family of oncogenes consists of three closely related proteins in mammals: c-Myc, N-Myc and L-Myc. These proteins share the same biochemical properties, exert mostly the same functions, but are most often expressed in mutually exclusive patterns. Myc is now emerging as a key factor in maintenance of embryonic and adult stem cells as well as in reacquisition of stem cell properties, including induced reprogramming. We previously showed that c-Myc deficiency can cause the accumulation of hematopoietic stem cells (HSCs) due to a niche dependent differentiation defect. HSCs are responsible for life-long replenishment of all blood cell types, and are defined by their ability to self-renew while concomitantly giving rise to more commited progenitors. To gain further insight into the function of Myc in HSCs, in this study we combine the use of genetically-modified mouse models with the systematic characterization of c-myc, N-myc and L-myc transcription patterns throughout the hematopoietic system. Interestingly, the most immature HSCs express not only c-myc, but also about equal amounts of N-myc transcripts. Although conditional deletion of N-myc alone in the bone marrow does not affect steady-state hematopoiesis, N-myc null HSCs show impaired long-term self-renewal capacity. Strikingly, combined deficiency of c-Myc and N-Myc results in pan-cytopenia and rapid lethality, due to the apoptosis of most hematopoietic cell types. In particular, self-renewing HSCs, but not quiescent HSCs or progenitor cell types rapidly up-regulate and accumulate the potent cytotoxic molecule GranzymeB (GrB), causing their rapid cell death. These data uncover a novel pathway on which HSC survival depends on, namely repression of GrB, a molecule typically used by the innate immune system to eliminate tumor and virus infected cells. To evaluate the extent of redundancy between c-Myc and N-Myc in HSCs, we examined mice in which c-myc coding sequences are replaced by that of N-myc (NCR) and also generated an allelic series of myc, by combinatorially deleting one or several c-myc and/or N-myc alleles. While the analysis of NCR mice suggests that c-Myc and N-Myc are qualitatively functionally redundant, our allelic series indicates that the efficiencies with which these two proteins affect crucial HSC maintenance processes are likely to be distinct. Collectively, our genetic data show that general "MYC" activity delivered by c-Myc and N-Myc controls crucial aspects of HSC function, including self-renewal, survival and niche dependent differentiation.

Improving prediction of recanalization in acute large-vessel occlusive stroke.

BACKGROUND: Recanalization in acute ischemic stroke with large-vessel occlusion is a potent indicator of good clinical outcome. OBJECTIVE: To identify easily available clinical and radiologic variables predicting recanalization at various occlusion sites. METHODS: All consecutive, acute stroke patients from the Acute STroke Registry and Analysis of Lausanne (2003-2011) who had a large-vessel occlusion on computed tomographic angiography (CTA) (< 12 h) were included. Recanalization status was assessed at 24 h (range: 12-48 h) with CTA, magnetic resonance angiography, or ultrasonography. Complete and partial recanalization (corresponding to the modified Treatment in Cerebral Ischemia scale 2-3) were grouped together. Patients were categorized according to occlusion site and treatment modality. RESULTS: Among 439 patients, 51% (224) showed complete or partial recanalization. In multivariate analysis, recanalization of any occlusion site was most strongly associated with endovascular treatment, including bridging therapy (odds ratio [OR] 7.1, 95% confidence interval [CI] 2.2-23.2), and less so with intravenous thrombolysis (OR 1.6, 95% CI 1.0-2.6) and recanalization treatments performed beyond guidelines (OR 2.6, 95% CI 1.2-5.7). Clot location (large vs. intermediate) and tandem pathology (the combination of intracranial occlusion and symptomatic extracranial stenosis) were other variables discriminating between recanalizers and non-recanalizers. For patients with intracranial occlusions, the variables significantly associated with recanalization after 24 h were: baseline National Institutes of Health Stroke Scale (NIHSS) (OR 1.04, 95% CI 1.02-1.1), Alberta Stroke Program Early CT Score (ASPECTS) on initial computed tomography (OR 1.2, 95% CI 1.1-1.3), and an altered level of consciousness (OR 0.2, 95% CI 0.1-0.5). CONCLUSIONS: Acute endovascular treatment is the single most important factor promoting recanalization in acute ischemic stroke. The presence of extracranial vessel stenosis or occlusion decreases recanalization rates. In patients with intracranial occlusions, higher NIHSS score and ASPECTS and normal vigilance facilitate recanalization. Clinical use of these predictors could influence recanalization strategies in individual patients.

Fas ligand-induced proinflammatory transcriptional responses in reconstructed human epidermis. Recruitment of the epidermal growth factor receptor and activation of MAP kinases.

Fas ligand (FasL) exerts potent proapoptotic and proinflammatory actions on epidermal keratinocytes and has been implicated in the pathogenesis of eczema, toxic epidermal necrolysis, and drug-induced skin eruptions. We used reconstructed human epidermis to investigate the mechanisms of FasL-induced inflammatory responses and their relationships with FasL-triggered caspase activity. Caspase activity was a potent antagonist of the pro-inflammatory gene expression triggered by FasL prior to the onset of cell death. Furthermore, we found that FasL-stimulated autocrine production of epidermal growth factor receptor (EGFR) ligands, and the subsequent activation of EGFR and ERK1 and ERK2 mitogen-activated protein kinases, were obligatory extracellular steps for the FasL-induced expression of a subset of inflammatory mediators, including CXCL8/interleukin (IL)-8, ICAM-1, IL-1alpha, IL-1beta, CCL20/MIP-3alpha, and thymic stromal lymphopoietin. These results expand the known physiological role of EGFR and its ligands from promoting keratinocyte mitogenesis and survival to mediating FasL-induced epidermal inflammation.

Long circulating half-life and high tumor selectivity of the photosensitizer meta-tetrahydroxyphenylchlorin conjugated to polyethylene glycol in nude mice grafted with a human colon carcinoma.

In a mode of nude mice bearing a human colon carcinoma xenograft, the biodistribution and tumor localization of metatetrahydroxyphenylchlorin (m-THPC) coupled to polyethylene glycol (PEG) were compared with those of the free form of this photosensitizer used in photodynamic therapy (PDT). At different times after i.v. injection of both forms of 125I-labeled photosensitizer, m-THPC-PEG gave on average a 2-fold higher tumor uptake than free m-THPC. In addition, at early times after injection, m-THPC-PEG showed a 2-fold longer blood circulating half-life and a 4-fold lower liver uptake than free m-THPC. The tumor to normal tissue ratios of radioactivity concentrations were always higher for m-THPC-PEG than for free m-THPC at any time point studied from 2 to 96 hr post-injection. Significant coefficients of correlation between direct fluorescence measurements and radioactivity counting were obtained within each organ tested. Fluorescence microscopy studies showed that m-THPC-PEG was preferentially localized near the tumor vessels, whereas m-THPC was more diffusely distributed inside the tumor tissue. To verify whether m-THPC-PEG conjugate remained phototoxic in vivo, PDT experiments were performed 72 hr after injection and showed that m-THPC-PEG was as potent as free m-THPC in the induction of tumor regression provided that the irradiation does for m-THPC-PEG conjugate was adapted to a well-tolerated 2-fold higher level. The overall results demonstrate first the possibility of improving the in vivo tumor localization of a hydrophobic dye used for PDT by coupling it to PEG and second that a photosensitizer conjugated to a macromolecule can remain phototoxic in vivo.

The ALK-F1174L activating mutation is tumorigenic in MONC-1 neural crest stem cells in an orthotopic murine model of neuroblastoma

Background: Activating mutations of the anaplastic lymphoma receptor tyrosine kinase gene (ALK) were identified in both somatic and familial neuroblastoma. The most common somatic mutation, F1174L, is associated with NMYC amplification and displayed an efficient transforming activity in vivo. In addition, both AKL-F1174L and NMYC were shown cooperate in neuroblastoma tumorigenesis in animal models. To analyse the role of ALK mutations in the oncogenesis of neuroblastoma, ALK wt and various ALK mutants were transduced in murine neural crest stem cells (MONC1). Methods: ALK-wt, and F1174L, and R1275Q mutants were stably expressed by retroviral infection using the pMIGR1 vector in the murine neural crest stem cell line MONC-1, previously immortalised with v-myc, and further implanted subcutaneously or orthotopically in nude mice. Results: Both MONC1-ALK-F1174L and -R1275Q cells displayed a rapid tumour forming capacity upon subcutaneous injection in nude mice compared to control MONC1-MIGR or MONC1 cells. Interestingly, the transforming capacity of the F1174L mutant was much more potent compared to that of R1275Q mutant in murine neural crest stem cells, while ALK-wt was not tumorigenic. In addition, mice implanted orthotopically in the left adrenal gland with MONC1-ALK-F1174L cells developed highly aggressive tumours in 100% of mice within three weeks, while MONC1-Migr or MONC1 derived tumours displayed a longer latency and a reduced tumour take. Conclusions: The activating ALK-F1174L mutant is highly tumorigenic in neural crest stem cells. Nevertheless, we cannot exclude a functional implication of the v-myc oncogene used for MONC1 cells immortalisation. Indeed, the control MONC1-Migr and MONC1 cells were also able to derive subcutaneous and orthotopic tumours, although with considerable reduced efficiency. Further investigations using neural crest stem cell lacking exogenous myc expression are currently on way to assess the exclusive role of ALK mutations in NB oncogenesis.

Gene transfer of interleukin-18-binding protein attenuates cardiac allograft rejection.

Interleukin (IL) 18 is a potent pro-inflammatory Th1 cytokine that exerts pleiotropic effector functions in both innate and acquired immune responses. Increased IL-18 production during acute rejection has been reported in experimental heart transplantation models and in kidney transplant recipients. IL-18-binding protein (IL-18BP) binds IL-18 with high affinity and neutralizes its biologic activity. We have analyzed the efficacy of an adenoviral vector expressing an IL-18BP-Ig fusion protein in a rat model of heart transplantation. IL-18BP-Ig gene transfer into Fisher (F344) rat donor hearts resulted in prolonged graft survival in Lewis recipients (15.8 +/- 1.4 days vs. 10.3 +/- 2.5 and 10.1 +/- 2.1 days with control virus and buffer solution alone, respectively; P < 0.001). Immunohistochemical analysis revealed decreased intra-graft infiltrates of monocytes/macrophages, CD4(+), CD8alpha(+) and T-cell receptor alphabeta(+) cells after IL-18BP-Ig versus mock gene transfer (P < 0.05). Real-time reverse transcriptase polymerase chain reaction analysis showed decreased cytokine transcripts for the RANTES chemokine and transforming growth factor-beta after IL-18BP-Ig gene transfer (P < 0.05). IL-18BP-Ig gene transfer attenuates inflammatory cell infiltrates and prolongs cardiac allograft survival in rats. These results suggest a contributory role for IL-18 in acute rejection. Further studies aiming at defining the therapeutic potential of IL-18BP are warranted.

In kittiwakes food availability partially explains the seasonal decline in immunocompetence

1. The immune system plays an important role in fitness, and interindividual variation in immunocompetence is due to several factors including food supply. 2. Seasonal variation in food resources may therefore explain why immunocompetence in bird nestlings usually declines throughout the breeding season, with chicks born early in the season receiving more food than chicks born later, and thereby possibly developing a more potent immune system. Although there are studies supporting this hypothesis, none has been experimental. 3. We performed an experiment in the kittiwake Rissa tridactyla by manipulating the food supply of pairs that were left to produce a first brood, and of pairs that were induced to produce a late replacement brood. 4. If food supply mediates, at least partially, seasonal variations in chick immunocompetence, non-food-supplemented chicks would show a stronger seasonal decline in immunocompetence than food-supplemented chicks. 5. Food supplementation improved humoral immunocompetence (the production of immunoglobulins Y), but not T-cell immunocompetence (phytohaemagglutinin, PHA response). T-cell immunocompetence of food-supplemented and non-food-supplemented chicks decreased through the season but to a similar extent, whereas the humoral immunocompetence of non-food-supplemented chicks decreased more strongly than that of food-supplemented chicks. 6. Our results suggest that the seasonal decline in humoral immunocompetence can be explained, at least partly, by variations in food supply throughout the breeding season.

Beclin 1-independent autophagy contributes to apoptosis in cortical neurons.

Neuronal autophagy is enhanced in many neurological conditions, such as cerebral ischemia and traumatic brain injury, but its role in associated neuronal death is controversial, especially under conditions of apoptosis. We therefore investigated the role of autophagy in the apoptosis of primary cortical neurons treated with the widely used and potent pro-apoptotic agent, staurosporine (STS). Even before apoptosis, STS enhanced autophagic flux, as shown by increases in autophagosomal (LC3-II level, LC3 punctate labeling) and lysosomal (cathepsin D, LAMP1, acid phosphatase, β-hexasominidase) markers. Inhibition of autophagy by 3-methyladenine, or by lentivirally-delivered shRNAs against Atg5 and Atg7, strongly reduced the STS-induced activation of caspase-3 and nuclear translocation of AIF, and gave partial protection against neuronal death. Pan-caspase inhibition with Q-VD-OPH likewise protected partially against neuronal death, but failed to affect autophagy. Combined inhibition of both autophagy and caspases gave strong synergistic neuroprotection. The autophagy contributing to apoptosis was Beclin 1-independent, as shown by the fact that Beclin 1 knockdown failed to reduce it but efficiently reduced rapamycin-induced autophagy. Moreover the Beclin 1 knockdown sensitized neurons to STS-induced apoptosis, indicating a cytoprotective role of Beclin 1 in cortical neurons. Caspase-3 activation and pyknosis induced by two other pro-apoptotic stimuli, MK801 and etoposide, were likewise found to be associated with Beclin 1-independent autophagy and reduced by the knockdown of Atg7 but not Beclin 1. In conclusion, Beclin 1-independent autophagy is an important contributor to both the caspase-dependent and -independent components of neuronal apoptosis and may be considered as an important therapeutic target in neural conditions involving apoptosis.