Using demographic characteristics of populations to detect spatial fragmentation following suspected ebola outbreaks in great apes.

OBJECTIVES: Demographic crashes due to emerging diseases can contribute to population fragmentation and increase extinction risk of small populations. Ebola outbreaks in 2002-2004 are suspected to have caused a decline of more than 80% in some Western lowland gorilla (Gorilla gorilla gorilla) populations. We investigated whether demographic indicators of this event allowed for the detection of spatial fragmentation in gorilla populations. MATERIALS AND METHODS: We collected demographic data from two neighbouring populations: the Lokoué population, suspected to have been affected by an Ebola outbreak (followed from 2001 to 2014), and the Romani population, of unknown demographic status before Ebola outbreaks (followed from 2005 to 2014). RESULTS: Ten years after the outbreak, the Lokoué population is slowly recovering and the short-term demographic indicators of a population crash were no longer detectable. The Lokoué population has not experienced any additional demographic perturbation over the past decade. The Romani population did not show any of the demographic indicators of a population crash over the past decade. Its demographic structure remained similar to that of unaffected populations. DISCUSSION: Our results highlighted that the Ebola disease could contribute to fragmentation of gorilla populations due to the spatially heterogeneous impact of its outbreaks. The demographic structure of populations (i.e., age-sex and group structure) can be useful indicators of a possible occurrence of recent Ebola outbreaks in populations without known history, and may be more broadly used in other emerging disease/species systems. Longitudinal data are critical to our understanding of the impact of emerging diseases on wild populations and their conservation.

How Ebola impacts social dynamics in gorillas: a multistate modelling approach.

Emerging infectious diseases can induce rapid changes in population dynamics and threaten population persistence. In socially structured populations, the transfers of individuals between social units, for example, from breeding groups to non-breeding groups, shape population dynamics. We suggest that diseases may affect these crucial transfers. We aimed to determine how disturbance by an emerging disease affects demographic rates of gorillas, especially transfer rates within populations and immigration rates into populations. We compared social dynamics and key demographic parameters in a gorilla population affected by Ebola using a long-term observation data set including pre-, during and post-outbreak periods. We also studied a population of undetermined epidemiological status in order to assess whether this population was affected by the disease. We developed a multistate model that can handle transition between social units while optimizing the number of states. During the Ebola outbreak, social dynamics displayed increased transfers from a breeding to a non-breeding status for both males and females. Six years after the outbreak, demographic and most of social dynamics parameters had returned to their initial rates, suggesting a certain resilience in the response to disruption. The formation of breeding groups increased just after Ebola, indicating that environmental conditions were still attractive. However, population recovery was likely delayed because compensatory immigration was probably impeded by the potential impact of Ebola in the surrounding areas. The population of undetermined epidemiological status behaved similarly to the other population before Ebola. Our results highlight the need to integrate social dynamics in host-population demographic models to better understand the role of social structure in the sensitivity and the response to disease disturbances.

CD93 is required for maintenance of antibody secretion and persistence of plasma cells in the bone marrow niche.

Plasma cells represent the end stage of B-cell development and play a key role in providing an efficient antibody response, but they are also involved in numerous pathologies. Here we show that CD93, a receptor expressed during early B-cell development, is reinduced during plasma-cell differentiation. High CD93/CD138 expression was restricted to antibody-secreting cells both in T-dependent and T-independent responses as naive, memory, and germinal-center B cells remained CD93-negative. CD93 was expressed on (pre)plasmablasts/plasma cells, including long-lived plasma cells that showed decreased cell cycle activity, high levels of isotype-switched Ig secretion, and modification of the transcriptional network. T-independent and T-dependent stimuli led to re-expression of CD93 via 2 pathways, either before or after CD138 or Blimp-1 expression. Strikingly, while humoral immune responses initially proceeded normally, CD93-deficient mice were unable to maintain antibody secretion and bone-marrow plasma-cell numbers, demonstrating that CD93 is important for the maintenance of plasma cells in bone marrow niches.

European Respiratory Society clinical practice guidelines: methodological guidance.

ERS has published official methodological guidance for clinical practice guidelines. ERS recommends this to ensure that state-of-the-art guidelines are developed. https://bit.ly/3xP5SSr.

Disease avoidance, and breeding group age and size condition the dispersal patterns of western lowland gorilla females.

Social dispersal is an important feature of population dynamics. When female mammals occur in polygynous groups, their dispersal decisions are conditioned by various female-, male-, and group-related factors. Among them, the influence of disease often remains difficult to assess. To address this challenge, we used long-term monitoring data from two gorilla populations (Gorilla gorilla gorilla) affected by infectious skin disease lesions. After controlling for other potentially influential factors, we investigated to which extent disease avoidance drives the dispersal decisions of gorilla females. We showed that the infection of a silverback of a breeding group by the skin disease increased the probability of adult females to emigrate. Moreover, adult females avoided breeding groups with a high prevalence of skin disease by emigrating from them and immigrating into healthier ones. Age of the breeding group was also an important factor. Adult females left older groups, near the end of a male tenure, to join younger ones led by younger fully grown silverbacks that could be of high reproductive and protective value. Our study highlights that, although females select for high-quality males, disease avoidance is a critical driver of their dispersion decision.

Dominant Role of CD80-CD86 Over CD40 and ICOSL in the Massive Polyclonal B Cell Activation Mediated by LAT(Y136F) CD4(+) T Cells.

Coordinated interactions between T and B cells are crucial for inducing physiological B cell responses. Mutant mice in which tyrosine 136 of linker for activation of T cell (LAT) is replaced by a phenylalanine (Lat(Y136F)) exhibit a strong CD4(+) T cell proliferation in the absence of intended immunization. The resulting effector T cells produce high amounts of T(H)2 cytokines and are extremely efficient at inducing polyclonal B cell activation. As a consequence, these Lat(Y136F) mutant mice showed massive germinal center formations and hypergammaglobulinemia. Here, we analyzed the involvement of different costimulators and their ligands in such T-B interactions both in vitro and in vivo, using blocking antibodies, knockout mice, and adoptive transfer experiments. Surprisingly, we showed in vitro that although B cell activation required contact with T cells, CD40, and inducible T cell costimulator molecule-ligand (ICOSL) signaling were not necessary for this process. These observations were further confirmed in vivo, where none of these molecules were required for the unfolding of the LAT CD4(+) T cell expansion and the subsequent polyclonal B cell activation, although, the absence of CD40 led to a reduction of the follicular B cell response. These results indicate that the crucial functions played by CD40 and ICOSL in germinal center formation and isotype switching in physiological humoral responses are partly overcome in Lat(Y136F) mice. By comparison, the absence of CD80-CD86 was found to almost completely block the in vitro B cell activation mediated by Lat(Y136F) CD4(+) T cells. The role of CD80-CD86 in T-B cooperation in vivo remained elusive due to the upstream implication of these costimulatory molecules in the expansion of Lat(Y136F) CD4(+) T cells. Together, our data suggest that CD80 and CD86 costimulators play a key role in the polyclonal B cell activation mediated by Lat(Y136F) CD4(+) T cells even though additional costimulatory molecules or cytokines are likely to be required in this process.

Recovery potential of a western lowland gorilla population following a major Ebola outbreak: results from a ten year study.

Investigating the recovery capacity of wildlife populations following demographic crashes is of great interest to ecologists and conservationists. Opportunities to study these aspects are rare due to the difficulty of monitoring populations both before and after a demographic crash. Ebola outbreaks in central Africa have killed up to 95% of the individuals in affected western lowland gorilla (Gorilla gorilla gorilla) populations. Assessing whether and how fast affected populations recover is essential for the conservation of this critically endangered taxon. The gorilla population visiting Lokoué forest clearing, Odzala-Kokoua National Park, Republic of the Congo, has been monitored before, two years after and six years after Ebola affected it in 2004. This allowed us to describe Ebola's short-term and long-term impacts on the structure of the population. The size of the population, which included around 380 gorillas before the Ebola outbreak, dropped to less than 40 individuals after the outbreak. It then remained stable for six years after the outbreak. However, the demographic structure of this small population has significantly changed. Although several solitary males have disappeared, the immigration of adult females, the formation of new breeding groups, and several birth events suggest that the population is showing potential to recover. During the outbreak, surviving adult and subadult females joined old solitary silverbacks. Those females were subsequently observed joining young silverbacks, forming new breeding groups where they later gave birth. Interestingly, some females were observed joining silverbacks that were unlikely to have sired their infant, but no infanticide was observed. The consequences of the Ebola outbreak on the population structure were different two years and six years after the outbreak. Therefore, our results could be used as demographic indicators to detect and date outbreaks that have happened in other, non-monitored gorilla populations.

Th2 lymphoproliferative disorder of LatY136F mutant mice unfolds independently of TCR-MHC engagement and is insensitive to the action of Foxp3+ regulatory T cells.

Mutant mice where tyrosine 136 of linker for activation of T cells (LAT) was replaced with a phenylalanine (Lat(Y136F) mice) develop a fast-onset lymphoproliferative disorder involving polyclonal CD4 T cells that produce massive amounts of Th2 cytokines and trigger severe inflammation and autoantibodies. We analyzed whether the Lat(Y136F) pathology constitutes a bona fide autoimmune disorder dependent on TCR specificity. Using adoptive transfer experiments, we demonstrated that the expansion and uncontrolled Th2-effector function of Lat(Y136F) CD4 cells are not triggered by an MHC class II-driven, autoreactive process. Using Foxp3EGFP reporter mice, we further showed that nonfunctional Foxp3(+) regulatory T cells are present in Lat(Y136F) mice and that pathogenic Lat(Y136F) CD4 T cells were capable of escaping the control of infused wild-type Foxp3(+) regulatory T cells. These results argue against a scenario where the Lat(Y136F) pathology is primarily due to a lack of functional Foxp3(+) regulatory T cells and suggest that a defect intrinsic to Lat(Y136F) CD4 T cells leads to a state of TCR-independent hyperactivity. This abnormal status confers Lat(Y136F) CD4 T cells with the ability to trigger the production of Abs and of autoantibodies in a TCR-independent, quasi-mitogenic fashion. Therefore, despite the presence of autoantibodies causative of severe systemic disease, the pathological conditions observed in Lat(Y136F) mice unfold in an Ag-independent manner and thus do not qualify as a genuine autoimmune disorder.

A novel H19 antisense RNA overexpressed in breast cancer contributes to paternal IGF2 expression.

The H19/IGFf2 locus belongs to a large imprinted domain located on human chromosome 11p15.5 (homologue to mouse distal chromosome 7). The H19 gene is expressed from the maternal allele, while IGF2 is paternally expressed. Natural antisense transcripts and intergenic transcription have been involved in many aspects of eukaryotic gene expression, including genomic imprinting and RNA interference. However, apart from the identification of some IGF2 antisense transcripts, few data are available on that topic at the H19/IGF2 locus. We identify here a novel transcriptional activity at both the human and the mouse H19/IGF2 imprinted loci. This activity occurs antisense to the H19 gene and has the potential to produce a single 120-kb transcript that we called the 91H RNA. This nuclear and short-lived RNA is not imprinted in mouse but is expressed predominantly from the maternal allele in both mice and humans within the H19 gene region. Moreover, the transcript is stabilized in breast cancer cells and overexpressed in human breast tumors. Finally, knockdown experiments showed that, in humans, 91H, rather than affecting H19 expression, regulates IGF2 expression in trans.

The Th2 lymphoproliferation developing in LatY136F mutant mice triggers polyclonal B cell activation and systemic autoimmunity.

Lat(Y136F) knock-in mice harbor a point mutation in Tyr(136) of the linker for activation of T cells and show accumulation of Th2 effector cells and IgG1 and IgE hypergammaglobulinemia. B cell activation is not a direct effect of the mutation on B cells since in the absence of T cells, mutant B cells do not show an activated phenotype. After adoptive transfer of linker for activation of T cell mutant T cells into wild-type, T cell-deficient recipients, recipient B cells become activated. We show in vivo and in vitro that the Lat(Y136F) mutation promotes T cell-dependent B cell activation leading to germinal center, memory, and plasma cell formation even in an MHC class II-independent manner. All the plasma and memory B cell populations found in physiological T cell-dependent B cell responses are found. Characterization of the abundant plasmablasts found in secondary lymphoid organs of Lat(Y136F) mice revealed the presence of a previously uncharacterized CD93-expressing subpopulation, whose presence was confirmed in wild-type mice after immunization. In Lat(Y136F) mice, B cell activation was polyclonal and not Ag-driven because the increase in serum IgG1 and IgE concentrations involved Abs and autoantibodies with different specificities equally. Although the noncomplement-fixing IgG1 and IgE are the only isotypes significantly increased in Lat(Y136F) serum, we observed early-onset systemic autoimmunity with nephritis showing IgE autoantibody deposits and severe proteinuria. These results show that Th2 cells developing in Lat(Y136F) mice can trigger polyclonal B cell activation and thereby lead to systemic autoimmune disease.

Short fluorodeoxyuridine exposure of different human glioblastoma lines induces high-level accumulation of S-phase cells that avidly incorporate 125I-iododeoxyuridine.

PURPOSE: Radio-iododeoxyuridine (IdUrd) is a potential Auger radiation therapy agent incorporated into DNA during the synthesis phase. In this study we sought to optimise S-phase targeting by modulating cellular cycling and radio-IdUrd DNA incorporation using short non-toxic fluorodeoxyuridine (FdUrd) incubations. METHODS: Three human glioblastoma cell lines with different p53 expression were pre-treated with various FdUrd conditions. After different intervals, (125)I-IdUrd DNA incorporation was measured. Fluorescence-activated cell sorter cell cycle analysis was performed after identical intervals post FdUrd pre-treatment. RESULTS: The highest increase in (125)I-IdUrd DNA incorporation was induced by 1-h incubation with 1 muM FdUrd. Increase in radio-IdUrd DNA incorporation was greatest 16-24 h after FdUrd, reaching factors of >or=7.5 over baseline incorporation in the three cell lines. Furthermore, cell synchronisation in S phase was observed with a peak of >or=69.5% in the three cell lines at 16 and 24 h post FdUrd, corresponding to an increase of 2.5-4.1 over baseline. CONCLUSION: FdUrd-induced thymidine synthesis inhibition led to S-phase accumulation that was maximal after an interval of 16-24 h and time-correlated with the highest radio-IdUrd DNA incorporation. These observations might allow the rational design of an Auger radiation therapy targeting a maximal number of S-phase cells in single treatment cycles.