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Numerous patient-based studies have highlighted the protective role of immunoglobulin E-mediated allergic diseases on glioblastoma (GBM) susceptibility and prognosis. However, the mechanisms behind this observation remain elusive. Our objective was to establish a preclinical model able to recapitulate this phenomenon and investigate the role of immunity underlying such protection.An immunocompetent mouse model of allergic airway inflammation (AAI) was initiated before intracranial implantation of mouse GBM cells (GL261). RAG1-KO mice served to assess tumor growth in a model deficient for adaptive immunity. Tumor development was monitored by MRI. Microglia were isolated for functional analyses and RNA-sequencing. Peripheral as well as tumor-associated immune cells were characterized by flow cytometry. The impact of allergy-related microglial genes on patient survival was analyzed by Cox regression using publicly available datasets.We found that allergy establishment in mice delayed tumor engraftment in the brain and reduced tumor growth resulting in increased mouse survival. AAI induced a transcriptional reprogramming of microglia towards a pro-inflammatory-like state, uncovering a microglia gene signature, which correlated with limited local immunosuppression in glioma patients. AAI increased effector memory T-cells in the circulation as well as tumor-infiltrating CD4Our results demonstrate that AAI limits both tumor take and progression in mice, providing a preclinical model to study the impact of allergy on GBM susceptibility and prognosis, respectively. We identify a potentiation of local and adaptive systemic immunity, suggesting a reciprocal crosstalk that orchestrates allergy-induced immune protection against GBM.

HIV-1 persists in viral reservoirs of latently infected CD4+T cells containing integrated replication-competent viral DNA. Combined Antiretroviral Therapy (cART) does not eradicate HIV-1 reservoirs and treatment interruption will ultimately lead to viral load rebound. HIV-1 infection dramatically reduces the proportion of functional NK cell subsets and increases the expression of the checkpoint inhibitors NKG2A and KIR2DL. In this regard, we developed novel recombinant molecules combining multimers of the IL-15/IL-15Rα complex with the single-chain fragment variables (scFvs) of NKG2A or KIR2DL, and named them as Natural killer activating Multimeric immunotherapeutic compleXes (NaMiX). NaMiX significantly improved the cytotoxic activity of NK cells against HIV-1 positive ACH-2 cells and resistant Raji cancer cells by increasing their degranulation capacity, release of granzyme B, perforin and IFN-γ expression. Targeting the NKG2A receptor had a stronger effect compared to the targeting of the KIR2DL receptor due to its higher expression on NK cells. In a viral inhibition assay using CD4+T cells from HIV-1 positive patients under cART, NaMiX initially increased viral replication which was subsequently inhibited by stimulated NK cells. In humanized NSG tg-huIL-15 mice showing functional NK cells, we observed enhanced activation, degranulation and killing by NK cells from the spleen of mice treated with anti-NKG2A NaMiX compared to the cells of control mice previously infected with HIV-1 and treated with cART. Although NaMiX did not delay viral load rebound after treatment interruption in a first attempt, it tend to decrease total HIV-1 DNA in the lungs of the mice. Blocking the inhibitory receptor NKG2A in combination with targeted multimers of IL-15 on NK cells could therefore be a promising immunotherapeutic strategy towards HIV-1 functional cure.

The autonomic nervous system is a master regulator of homeostatic processes and stress responses. Sympathetic noradrenergic nerve fibers decrease bone mass, but the role of cholinergic signaling in bone has remained largely unknown. Here, we describe that early postnatally, a subset of sympathetic nerve fibers undergoes an interleukin-6 (IL-6)-induced cholinergic switch upon contacting the bone. A neurotrophic dependency mediated through GDNF-family receptor-α2 (GFRα2) and its ligand, neurturin (NRTN), is established between sympathetic cholinergic fibers and bone-embedded osteocytes, which require cholinergic innervation for their survival and connectivity. Bone-lining osteoprogenitors amplify and propagate cholinergic signals in the bone marrow (BM). Moderate exercise augments trabecular bone partly through an IL-6-dependent expansion of sympathetic cholinergic nerve fibers. Consequently, loss of cholinergic skeletal innervation reduces osteocyte survival and function, causing osteopenia and impaired skeletal adaptation to moderate exercise. These results uncover a cholinergic neuro-osteocyte interface that regulates skeletogenesis and skeletal turnover through bone-anabolic effects., S.G. was supported by the NIH-OXCAM Program and the Gates Cambridge Trust. A.G.G. received fellowships from Ramón Areces and La Caixa Foundations. C.K. was supported by Marie Curie Career Integration grant H2020-MSCA-IF-2015-70841. M.S. and R.S. were supported by DFG, Se 697/7-1 and BMBF through the EnergI consortium TP6. J.V. and J.J.T.-A. were supported by Instituto de Salud Carlos III (PI12/02574), Junta de Andalucia (P12-CTS-2739), and, together with S.M.-F., by Red TerCel (ISCIII-Spanish Cell Therapy Network). S.A. and C.D.B. were supported by Versus Arthritis grant 21156. A.W.M. received funding from Versus Arthritis (21156). P.G.R. and S.G. were supported by the DIR, NIDCR, a part of the IRP, NIH, and DHHS (1ZIADE000380). K.E.S.P. acknowledges the support of the Cambridge NIHR Biomedical Research Centre. This work was supported by core support grants from MRC to the Cambridge Stem Cell Institute; National Health Service Blood and Transplant (United Kingdom), European Union’s Horizon 2020 research (ERC-2014-CoG-648765), MRC-AMED grant MR/V005421/1, and a Programme Foundation Award (C61367/A26670) from Cancer Research UK to S.M.-F. This research was funded in part by the Wellcome Trust (203151/Z/16/Z).

Food safety has considerably improved worldwide, yet infections with foodborne human enteric pathogens, such as Listeria spp. and Salmonella spp., still cause numerous hospitalizations and fatalities. Since dietary alterations, including fiber deficiency, might impact the colonization resistance mediated by the gut microbiome, studying the diet–microbiome–pathogen axis holds promise in further understanding the pathogenesis mechanisms. Using a gnotobiotic mouse model containing a 14-member synthetic human gut microbiota (14SM), we have previously shown that dietary fiber deprivation promotes proliferation of mucin-degrading bacteria, leading to a microbiome-mediated erosion of the colonic mucus barrier, which results in an increased susceptibility toward the rodent enteric pathogen Citrobacter rodentium. Here, we sought to understand how a low-fiber diet affects susceptibility to Listeria monocytogenes and Salmonella enterica serovar Typhimurium by using our 14SM gnotobiotic mouse model in BALB/c and C57BL/6 mouse backgrounds, respectively. Intriguingly, and in contrast to our results with C. rodentium, we observed that depriving mice of dietary fiber protected them from infections with both pathogens, compared to mice fed a standard chow. The microbiome delayed the overall pathogenicity compared to the onset of disease observed in germfree control mice. Nevertheless, we observed the same effect of diet on germfree mice, suggesting that the susceptibility is directly driven by the diet itself even in the absence of the gut microbiome. Our study points out an important observation, namely, that dietary fiber plays a crucial role in either the host’s susceptibility, the virulence of these pathogens, or both. It would be judicious to design and interpret future studies on this basis. IMPORTANCE The human enteric pathogens Listeria monocytogenes and Salmonella Typhimurium are employed as classical models in rodent hosts to understand the pathogenesis mechanisms of foodborne pathogens. Research in the past decade has stressed the importance of the gut microbial composition in modulating susceptibility to these pathogens. The results of our study—using gnotobiotic mice and germfree control animals—additionally suggest that the dietary fiber components can dominate the impact of enteropathogenic virulence over the pathogenicity-modulating properties of the gut microbiome. The significance of our research is that there is a need to carefully choose a certain chow when performing the enteropathogen-associated mouse experiments and to cautiously match the rodent diets when trying to replicate experiments across different laboratories. Finally, our data underscore the importance of using germfree control animals to study these pathogens, as our findings would have been prone to misinterpretation in the absence of these controls.

Despite significant progress in recent years, the therapeutic approach of the multiple different forms of human cancer often remains a challenge. Besides the well-established cancer surgery, radiotherapy and chemotherapy, immunotherapeutic strategies gain more and more attention, and some of them have already been successfully introduced into the clinic. Among these, immunotherapy based on natural killer (NK) cells is considered as one of the most promising options. In the present review, we will expose the different possibilities NK cells offer in this context, compare data about the theoretical background and mechanism(s) of action, report some results of clinical trials and identify several very recent trends. The pharmaceutical industry is quite interested in NK cell immunotherapy, which will benefit the speed of progress in the field.

Natural killer (NK) cells are important effectors of the innate immune system and participate in the first line of defense against infections and tumors. Prior to being functional, these lymphocytes must be educated or licensed through interactions of their major histocompatibility complex class I molecules with self-specific inhibitory receptors that recognize them. In the absence of such contacts, caused by either the lack of expression of the inhibitory receptors or a very low level of major histocompatibility complex class I (MHC class I) proteins, NK cells are hypo-reactive at baseline (ex vivo). After stimulation (assessed through plate-bound antibodies against activating receptors or culture in the presence of cytokines such as interleukin (IL)-2 or IL-15) however, they can become cytotoxic and produce cytokines. This is particularly the case in transporter associated with antigen processing (TAP)-deficient mice, which we investigated in the present study. Transporter associated with antigen processing transports endogenous peptides from the cytosol to the endoplasmic reticulum, where they are loaded on nascent MHC class I molecules, which then become stable and expressed at the cell surface. Consequently, TAP-KO mice have very low levels of MHC class I expression. We present a study about phenotypic and functional aspects of NK cells in two mouse strains, C57BL/6 wildtype and TAP1-KO in spleen and lung. We observed that in both types of mice, on the same genetic background, the initial pattern of education, conferred to the cellsviathe inhibitory receptors Ly49C/I and NKG2A, was maintained even after a strong stimulation by the cytokines interleukin-2, interleukin-12, interleukin-15 and interleukin-18. Furthermore, the percentages of activated NK cells expressing Ly49C/I and Ly49I were strongly down-modulated under these conditions. We completed our investigations with phenotypic studies of NK cells from these mice.

Early Life Adversity (ELA) is closely associated with the risk for developing diseases later in life, such as autoimmune diseases, type-2 diabetes and cardiovascular diseases. In humans, early parental separation, physical and sexual abuse or low social-economic status during childhood are known to have great impact on brain development, in the hormonal system and immune responses. Maternal deprivation (MD), the closest animal model available to the human situation, is known to similarly induce long lasting behavioural effects, to cause changes in the HPA axis and to have an impact in the immune system. Even though the immune responses to potential pathogens after early stress have been somehow documented, the mechanisms by which they occur are still not fully understood. Here, we have demonstrated that maternal separation, in both humans and rats, significantly affects the sensitivity of the immune system in adulthood. Particularly, NK cells’ profile and response to target cell lines are significantly changed after childhood adversity. These immune cells in rats are not only less cytotoxic towards YAC-1 cells, but also show a clear increase in the expression of maturation markers after 3h of maternal separation. Similarly, individuals who suffered from ELA display significant changes in the cytotoxic profile of NK cells together with decreased degranulation capacity. Altogether, these results lead us to conclude that one of the key mechanisms by which the immune system becomes impaired after ELA might be due to a shift on the senescent state of the cells, specifically NK cells. Elucidation of such a mechanism highlights the importance of ELA prevention and how NK targeted immunotherapy might help attenuating ELA consequences.

The discovery that NK cells are able to specifically recognize cells lacking the expression of self‐MHC class I molecules provided the first insight into NK cell recognition of tumour cells. It started a flourishing field of NK cell research aimed at exploring the molecular nature of NK cell receptors involved in tumour cell recognition. While much of the important early work was conducted in murine experimental model systems, studies of human NK cells rapidly followed. Over the years, human NK cell research has swiftly progressed, aided by new detailed molecular information on human NK cell development, differentiation, molecular specificity, tissue heterogeneity and functional capacity. NK cells have also been studied in many different diseases aside from cancer, including viral diseases, autoimmunity, allergy and primary immunodeficiencies. These fields of research have all, indirectly or directly, provided further insights into NK cell‐mediated recognition of target cells and paved the way for the development of NK cell‐based immunotherapies for human cancer. Excitingly, NK cell‐based immunotherapy now opens up for novel strategies aimed towards treating malignant diseases, either alone or in combination with other drugs. Reviewed here are some personal reflections of select contributions leading up to the current state‐of‐the‐art in the field, with a particular emphasis on contributions from our own laboratory. This review is part of a series of articles on immunology in Scandinavia, published in conjunction with the 50th anniversary of the Scandinavian Society for Immunology.

Natural killer (NK) cells are innate lymphoid cells at the interface between innate and adaptive immunity and mostly studied for their important roles in viral infections and malignant tumors. They can kill diseased cells and produce cytokines and chemokines, thereby shaping the adaptive immune response. Nowadays, NK cells are considered as a strong weapon for cancer immunotherapy and can for example be transduced to express tumor-specific chimeric antigen receptors or harnessed with therapeutic antibodies such as the so-called NK engagers. Whereas a large body of literature exists about the antiviral and antitumoral properties of NK cells, their potential role in bacterial infections is not that well delineated. Furthermore, NK cells are much more heterogeneous than previously thought and have tissue-characteristic features and phenotypes. This review gives an overview of airway NK cells and their position within the immunological army dressed against bacterial infections in the upper and predominantly the lower respiratory tracts. Whereas it appears that in several infections, NK cells play a non-redundant and protective role, they can likewise act as rather detrimental. The use of mouse models and the difficulty of access to human airway tissues for ethical reasons might partly explain the divergent results. However, new methods are appearing that are likely to reduce the heterogeneity between studies and to give a more coherent picture in this field.

The polymorphism of the gene FAM13A (family with sequence similarity 13, member A) is strongly linked to the risk of lung cancer and chronic obstructive pulmonary disease, which are among the leading causes of mortality and morbidity in lung-related diseases worldwide. However, the underlying molecular and cellular mechanisms through which FAM13A contributes to the pathogenesis of these diseases largely remain unclear. Here, using a Fam13a knock out (KO) mouse model, we showed that Fam13a depletion upregulated the expression of the terminal differentiation and inhibitory marker, KLRG1 (killer cell lectin-like receptor G1) in natural killer (NK) cells. NK cells from Fam13a-deficient mice showed impaired IFN-γ production either against target tumor cells or following various cytokine cocktail stimulations. Furthermore, the number of lung metastases induced by B16F10 melanoma cells was increased in Fam13a-KO mice. Collectively, our data suggest a key role of FAM13A in regulating NK cell functions, indicating that the key lung-disease risk gene FAM13A might contribute to the pathogenesis of several lung diseases via regulating NK cells.

The neurotrophic factors are well known for their implication in the growth and the survival of the central, sensory, enteric and parasympathetic nervous systems. Due to these properties, neurturin (NRTN) and Glial cell-derived neurotrophic factor (GDNF), which belong to the GDNF family ligands (GFLs), have been assessed in clinical trials as a treatment for neurodegenerative diseases like Parkinson’s disease. In addition, studies in favor of a functional role for GFLs outside the nervous system are accumulating. Thus, GFLs are present in several peripheral tissues, including digestive, respiratory, hematopoietic and urogenital systems, heart, blood, muscles and skin. More precisely, recent data have highlighted that different types of immune and epithelial cells (macrophages, T cells, such as, for example, mucosal-associated invariant T (MAIT) cells, innate lymphoid cells (ILC) 3, dendritic cells, mast cells, monocytes, bronchial epithelial cells, keratinocytes) have the capacity to release GFLs and express their receptors, leading to the participation in the repair of epithelial barrier damage after inflammation. Some of these mechanisms pass on to ILCs to produce cytokines (such as IL-22) that can impact gut microbiota. In addition, there are indications that NRTN could be used in the treatment of inflammatory airway diseases and it prevents the development of hyperglycemia in the diabetic rat model. On the other hand, it is suspected that the dysregulation of GFLs produces oncogenic effects. This review proposes the discussion of the biological understanding and the potential new opportunities of the GFLs, in the perspective of developing new treatments within a broad range of human diseases.

Background: To accompany the lifting of COVID-19 lockdown measures, Luxembourg implemented a mass testing programme. The first phase coincided with an early summer epidemic wave. Methods: High-throughput rRT-PCR was performed using a validated pooling strategy. The sampling infrastructure allowed the testing of the resident and cross-border worker populations. Test strategy was based on social connectivity within different activity sectors. Invitation frequencies were tactically increased in sectors and regions with higher prevalence. The results were analysed alongside contact tracing data. Findings: Sensitivity and specificity of the test protocol were 100%. The tests covered 49% of the resident and 22% of the cross-border worker populations. The programme identified 850 index cases with an additional 249 cases resulting from contact tracing, corresponding to 26% of positive cases of the epidemic wave. Enrichment in positive cases was observed in the services (11·4% increase over the mean prevalence), hospitality (8·6%) and construction (6·6%) sectors alongside regional differences. Strikingly, cases that were asymptomatic on the day of the positive result had a similar secondary attack rate in the household compared to those who were symptomatic. Based on simulations using a tailored agent-based SEIR model, the total number of expected cases would have been 39·1% higher without the mass screening programme. Mandatory participation would have resulted in a further difference of 41·4%. Interpretation: The implementation of strategic and tactical mass testing for SARS-CoV-2 allows the breaking of nascent infection chains and the suppression of epidemic dynamics. Asymptomatic carriers are at least as infectious as symptomatic patients. Containment of future outbreaks will critically depend on early testing in sectors and geographical regions. Higher participation rates must be assured through targeted incentivisation and recurrent invitation. Funding: This project was funded by the Luxembourg Ministries of Higher Education and Research, and Health. Declaration of Interests: All authors report grants from Luxembourg Ministry of Higher Education and Research, and Ministry of Health during the conduct of the study. Dr. Rodrigues reports working for the Ministry of Higher Education and Research as a public servant, during the conduct of the study. Dr. Snoeck reports that Fast Track Diagnostics provided a few SARS-CoV-2 rRT-PCR kits (RUO) free of charge at the time of evaluation of different commercial assays to be procured by the Luxembourg Government in order to do the mass screening intervention in the country. Ethics Approval Statement: The study was presented to the National Research Ethics Committee of Luxembourg (Comite National d’Ethique de Recherche, CNER) that approved its submission in its current form (ref. 1120-218).

Hematopoietic stem and progenitor cells (HSPCs) and leukocytes circulate between the bone marrow (BM) and peripheral blood following circadian oscillations. Autonomic sympathetic noradrenergic signals have been shown to regulate HSPC and leukocyte trafficking, but the role of the cholinergic branch has remained unexplored. We have investigated the role of the cholinergic nervous system in the regulation of day/night traffic of HSPCs and leukocytes in mice. We show here that the autonomic cholinergic nervous system (including parasympathetic and sympathetic) dually regulates daily migration of HSPCs and leukocytes. At night, central parasympathetic cholinergic signals dampen sympathetic noradrenergic tone and decrease BM egress of HSPCs and leukocytes. However, during the daytime, derepressed sympathetic noradrenergic activity causes predominant BM egress of HSPCs and leukocytes via β3–adrenergic receptor. This egress is locally supported by light-triggered sympathetic cholinergic activity, which inhibits BM vascular cell adhesion and homing. In summary, central (parasympathetic) and local (sympathetic) cholinergic signals regulate day/night oscillations of circulating HSPCs and leukocytes. This study shows how both branches of the autonomic nervous system cooperate to orchestrate daily traffic of HSPCs and leukocytes., This work was supported by core support grants from the Wellcome Trust and the Medical Research Council (MRC) to the Cambridge Stem Cell Institute, the Spanish Ministry of Economy and Competitiveness (SAF-2011-30308), the Pro-CNIC Foundation, Severo Ochoa Center of Excellence award SEV-2015-0505 to CNIC, Ramón y Cajal Program grant RYC-2009-04703, Marie Curie Career Integration grant FP7-PEOPLE-2011-RG-294096, ConSEPOC-Comunidad de Madrid S2010/BMD-2542, Red TerCel (Instituto de Salud Carlos III (ISCIII)-Spanish Cell Therapy Network), National Health Institute Blood and Transplant (United Kingdom), Horizon2020 grant ERC-2014-CoG-64765, and a Cancer Research UK Programme Foundation Award to S.M.-F., who was also supported in part by an International Early Career Scientist grant from the Howard Hughes Medical Institute. A.G.-G. received fellowships from the Ramón Areces and LaCaixa Foundations. C.K. was supported by Marie Curie Career Integration grant H2020-MSCA-IF-2015-708411.

Human NK cells can be subdivided into various subsets based on the relative expression of CD16 and CD56. In particular, CD56brightCD16−/dim NK cells are the focus of interest. They are considered efficient cytokine producers endowed with immunoregulatory properties, but they can also become cytotoxic upon appropriate activation. These cells were shown to play a role in different disease states, such as cancer, autoimmunity, neuroinflammation, and infection. Although their phenotype and functional properties are well known and have been extensively studied, their lineage relationship with other NK cell subsets is not fully defined, nor is their precise hematopoietic origin. In this article, we summarize recent studies about CD56bright NK cells in health and disease and briefly discuss the current controversies surrounding them.

Neurturin (NTN) was previously described for its neuronal activities, but recently, we have shown that this factor is also involved in asthma physiopathology. However, the underlying mechanisms of NTN are unclear. The aim of this study was to investigate NTN involvement in acute bronchial Th2 responses, to analyze its interaction with airway structural cells, and to study its implication in remodeling during acute and chronic bronchial inflammation in C57BL/6 mice. We analyzed the features of allergic airway inflammation in wild-type and NTN−/− mice after sensitization with two different allergens, OVA and house dust mite. We showed that NTN−/− dendritic cells and T cells had a stronger tendency to activate the Th2 pathway in vitro than similar wild-type cells. Furthermore, NTN−/− mice had significantly increased markers of airway remodeling like collagen deposition. NTN−/− lung tissues showed higher levels of neutrophils, cytokine-induced neutrophil chemoattractant, matrix metalloproteinase 9, TNF-α, and IL-6. Finally, NTN had the capacity to decrease IL-6 and TNF-α production by immune and epithelial cells, showing a direct anti-inflammatory activity on these cells. Our findings support the hypothesis that NTN could modulate the allergic inflammation in different mouse asthma models.

Immune responses are critical for the maintenance of homeostasis but can also upset the equilibrium, depending on the context and magnitude of the response. Natural killer (NK) cells are well known for their important roles in antiviral and antitumor immune responses, and they are currently used, mostly under optimized forms, as immunotherapeutic agents against cancer. Nevertheless, with accumulating examples of deleterious effects of NK cells, it is paramount to consider their negative contributions. Here, we critically review and comment on the literature surrounding undesirable aspects of NK cell activity, focusing on situations where they play a harmful rather than a protective role.

We characterized GBM patients' tumor and systemic immune contexture with aim to reveal themechanisms of immunological escape, their impact on patient outcome, and identify targets for immunotherapy. Increased CD3+ T-cell infiltration was associated with prolonged survival independent of age, MGMT promoter methylation and post-operative treatment that implies potential for immunotherapy for GBM. Several mechanisms of escape were identified: within the tumor microenvironment: induced CD8+CD28−Foxp3+ Tregs that may tolerize antigen presenting cells, elevated CD73 and CD39 ectonucleotidases that suppress T-cell function, and at the systemic level: elevated IL-10 levels in serum, diminished helper T-cell counts, and upregulated inhibitory CTLA-4. publishedVersion

Recent studies demonstrated that autophagy is an important regulator of innate immune response. However, the mechanism by which autophagy regulates natural killer (NK) cell-mediated antitumor immune responses remains elusive. Here, we demonstrate that hypoxia impairs breast cancer cell susceptibility to NK-mediated lysis in vitro via the activation of autophagy. This impairment was not related to a defect in target cell recognition by NK cells but to the degradation of NK-derived granzyme B in autophagosomes of hypoxic cells. Inhibition of autophagy by targeting beclin1 (BECN1) restored granzyme B levels in hypoxic cells in vitro and induced tumor regression in vivo by facilitating NK-mediated tumor cell killing. Together, our data highlight autophagy as a mechanism underlying the resistance of hypoxic tumor cells to NK-mediated lysis. The work presented here provides a cutting-edge advance in our understanding of the mechanism by which hypoxia-induced autophagy impairs NK-mediated lysis in vitro and paves the way for the formulation of more effective NK cell-based antitumor therapies.

NK cells are important players in immunity against pathogens and neoplasms. As a component of the innate immune system, they are one of the first effectors on sites of inflammation. Through their cytokine production capacities, NK cells participate in the development of a potent adaptive immune response. Furthermore, NK cells were found to have regulatory functions to limit and prevent autoimmunity via killing of autologous immune cells. These paradoxical functions of NK cells are reflected in CNS disorders. In this review, we discuss the phenotypes and functional features of peripheral and brain NK cells in brain tumors and infections, neurodegenerative diseases, acute vascular and traumatic damage, as well as mental disorders. We also discuss the implication of NK cells in neurotoxicity and neuroprotection following CNS pathology, as well as the crosstalk between NK cells and brain-resident immune cells.

Immune cell trafficking is crucial for surveillance and effector functions of the immune system. Circadian rhythms of the hypothalamic-pituitary-adrenal (HPA) axis and of cortisol have been implicated in circadian redistribution of circulating lymphocytes and granulocytes. However, information regarding the diurnal redistribution of immune cells and their temporal correlations with cortisol is scarce. In this study, we investigated the diurnal redistribution of T, B, and natural killer (NK) cell subsets in relation to the endogenous cortisol rhythm. Saliva and blood samples were collected every 15 min over an 8-h period. Salivary-free cortisol was measured by enzyme-linked immunosorbent assay (ELISA). Surface markers (CD3, CD19, CD8, CD56, CD16, KIR) were measured in whole blood samples by 6-color flow cytometry and cell subsets quantified as a percentage of the total lymphocyte population. To study associations between the diurnal cortisol rhythm and the redistribution of T, B, and NK cells, we calculated cross-correlations with lag periods of 15 min. The salivary cortisol levels showed the typical diurnal variations with a significant morning cortisol awakening response (CAR) peaking around 07:30 h followed by an afternoon nadir. Whereas B cells remained stable throughout the 8 h, T cells (CD3 + CD8+ and CD3 + CD8-) showed a significant positive cross-correlation with cortisol levels when a delay of 30-105 min was taken into account. This was followed by a negative correlation covering a period of 165-285 min after the cortisol peak. Conversely, NK cells showed an initial negative correlation at 45-105 min, followed by a positive correlation at 120-285 min. The major CD56 + CD16+ subset and the CD56 - CD16+ population showed similar temporal correlation profiles. The minor CD56 + CD16- NK cell subset showed no temporal changes. The major NK subset (CD56 + CD16+) contains cells with higher cytolytic activity (KIR+) cells, whereas the single-positive subsets CD56 + CD16- and CD56 - CD16+ are mainly involved in cytokine production. Significant positive correlations were observed in KIR+ subsets coincident with this of NK cells covering a period of 105-300 min after the cortisol peak. In conclusion, our results suggest that cortisol and the HPA axis orchestrate tidal waves of immune cells that are alternatively based toward innate and acquired immune surveillance.

Summary Background Immune thrombocytopenia (idiopathic thrombocytopenic purpura [ITP]) frequently occurs in young adults, particularly women in their third or fourth decade. The female predominance suggests that sex hormones may play a role in the different aspects of ITP. In this paper, we report a gender-related analysis of patients with ITP, specifically examining the clinical manifestations, responses to treatment and overall outcomes of the patients. Methods We included patients with “ITP” attending the departments of onco-hematology or internal medicine B (university hospital of Strasbourg, France) between 1990 and December 2010 The gender-related analysis was retrospective. Results We studied in 225 consecutive cases of established ITP with a follow-up period of 1.7 to 112 months The mean age of the patients was 44 years; 156 patients were female. The analysis revealed no significant statistical differences regarding patient characteristics between the female and male groups, with the exception of the following characteristics: the bleeding score, which altered in the presence of meno- and/or metrorrhagia and hematuria in female patients ( P = 0.03); the presence of anemia ( P = 0.04); and the detection of antinuclear and/or antiphospholipid antibodies ( P = 0.02). During the follow-up, no statistically significant difference was found regarding outcome or treatment response in relation to gender among these 225 patients (all P > 0.05). Discussion Gender does not appear to affect the manifestation of immune thrombocytopenia, the outcome or response to treatment. However, further large-scale randomized trials are needed to confirm these findings.

Familial hemophagocytic lymphohistiocytosis (FHL), is a rare autosomal recessive disorder characterized by an impairment of cytotoxic cells and uncontrolled activation of macrophages. This study presents the first description of four patients with FHL type 2 in Latin America. Patient 1 fulfilled the disease diagnostic criteria since 2 months of age, whereas patients 2, 3 and 4 exhibited the typical manifestations of the disease only later in their childhood. The PRF1 genetic analysis in these patients revealed two previously reported mutations: L17fsx50 and R54C. Interestingly, seven out of the 8 alleles evaluated here in patients carried the haplotype R54C/A91V, suggesting that this is a highly frequent FHL type 2 allele in Colombia. This haplotype confers residual cytotoxic function leading to late onset disease. Therefore, this report highlights the remarkable complexity of FHL diagnostic, emphasizing the importance of the genetic characterization of the disease.

Neurotrophins such as nerve growth factor and brain-derived neurotrophic factor have been described to be involved in the pathogenesis of asthma. Neurturin (NTN), another neurotrophin from the glial cell line-derived neurotrophic factor family, was shown to be produced by human immune cells: monocytes, B cells, and T cells. Furthermore, it was previously described that the secretion of inflammatory cytokines was dramatically stimulated in NTN knockout (NTN−/−) mice. NTN is structurally similar to TGF-β, a protective cytokine in airway inflammation. This study investigates the implication of NTN in a model of allergic airway inflammation using NTN−/− mice. The bronchial inflammatory response of OVA-sensitized NTN−/− mice was compared with wild-type mice. Airway inflammation, Th2 cytokines, and airway hyperresponsiveness (AHR) were examined. NTN−/− mice showed an increase of OVA-specific serum IgE and a pronounced worsening of inflammatory features. Eosinophil number and IL-4 and IL-5 concentration in the bronchoalveolar lavage fluid and lung tissue were increased. In parallel, Th2 cytokine secretion of lung draining lymph node cells was also augmented when stimulated by OVA in vitro. Furthermore, AHR was markedly enhanced in NTN−/− mice after sensitization and challenge when compared with wild-type mice. Administration of NTN before challenge with OVA partially rescues the phenotype of NTN−/− mice. These findings provide evidence for a dampening role of NTN on allergic inflammation and AHR in a murine model of asthma.

Natural killer (NK) cells are important effectors of both innate and adaptive immune responses. Although human and mouse NK cells are extensively characterized, much less is known about the rat cells, partly because of the current lack of reliable isolation techniques. We aimed to develop a method for isolating highly pure 'untouched' rat NK cells by negative selection from splenocytes. Thereafter, we characterized them phenotypically and functionally in comparison with those isolated by positive selection targeting the NKR-P1 receptor. Our novel method isolated highly pure untouched NK cells reproducibly with 97 ± 0.7% (n = 7), 96.6 ± 0.8% (n = 3) and 88.3 ± 1.5% (n = 9) in LEWIS, Fischer and athymic nude rats, respectively. The positively selected NK cells were less homogeneous and exhibited undesired method-related activation profiles. Resting negatively selected NK cells were less proliferative and less robust compared with positively selected NK cells. Although resting positively selected NK cells were more cytotoxic, interleukin-2 (IL-2) activation increased the cytotoxicity of negatively selected cells three-fold. The negatively selected NK cells responded to cross-linking of the NKR-P1 receptor by calcium mobilization from intracellular stores. However, combined IL-2 and IL-12 activation resulted in significantly more interferon-γ release from positively selected NK cells. This new NK-cell isolation method will allow a deeper insight into rat NK-cell phenotypes and the roles of their receptors in the biology of these cells.

Cobalamin (vitamin B12) deficiency is particularly common in the elderly (>65 years of age), but is often un- recognized because its clinical manifestations are subtle; however, they are also potentially serious, particularly from a neuropsychiatric and hematological perspectives. In the general population, the main causes of cobalamin deficiency are pernicious anemia and food-cobalamin malabsorption. Food-cobalamin malabsorption syndrome, which has only recently been identified, is a disorder characterized by the inability to release cobalamin from food or its binding proteins. This syndrome is usually caused by atrophic gastritis, related or unrelated to Helicobacter pylori infection, and long-term in- gestion of antacids and biguanides. Management of cobalamin deficiency with cobalamin injections is currently well codi- fied, but new routes of cobalamin administration (oral and nasal) are being studied, especially oral cobalamin therapy for food-cobalamin malabsorption.