Different features of Vδ2 T and NK cells in fatal and non-fatal human Ebola infections.

Human Ebola infection is characterized by a paralysis of the immune system. A signature of αβ T cells in fatal Ebola infection has been recently proposed, while the involvement of innate immune cells in the protection/pathogenesis of Ebola infection is unknown. Aim of this study was to analyze γδ T and NK cells in patients from the Ebola outbreak of 2014-2015 occurred in West Africa, and to assess their association with the clinical outcome

Unique human immune signature of Ebola virus disease in Guinea.

Despite the magnitude of the Ebola virus disease (EVD) outbreak in West Africa, there is still a fundamental lack of knowledge about the pathophysiology of EVD. In particular, very little is known about human immune responses to Ebola virus. Here we evaluate the physiology of the human T cell immune response in EVD patients at the time of admission to the Ebola Treatment Center in Guinea, and longitudinally until discharge or death. Through the use of multiparametric flow cytometry established by the European Mobile Laboratory in the field, we identify an immune signature that is unique in EVD fatalities. Fatal EVD was characterized by a high percentage of CD4(+) and CD8(+) T cells expressing the inhibitory molecules CTLA-4 and PD-1, which correlated with elevated inflammatory markers and high virus load. Conversely, surviving individuals showed significantly lower expression of CTLA-4 and PD-1 as well as lower inflammation, despite comparable overall T cell activation. Concomitant with virus clearance, survivors mounted a robust Ebola-virus-specific T cell response. Our findings suggest that dysregulation of the T cell response is a key component of EVD pathophysiology

NK cells in survivors and in fatalities.

<p>The frequency of NK (<b>A</b>), and of NK subsets (<b>B:</b> CD56^bright, CD56^dim, and CD56^neg) was analyzed in HD (n = 14), EBOV-survivors (n = 7) and EBOV-fatalities (n = 6). Statistical analysis was performed by using Mann Whitney test and differences were considered significant with a p<0.05, and highlighted with an asterisk. *: p<0.05; **: p<0.01; ***: p<0.001.</p

Frequency of Vδ2 T-cells in survivors and in fatalities.

<p>The frequency of Vδ2 (<b>A</b>), Vδ2^posCD95^pos (<b>B</b>), of Vδ2^posCCR7^neg (<b>C</b>) and Vδ2^posCTLA-4^pos (<b>D</b>) was analyzed in HD (n = 14), EBOV-survivors (n = 10) and EBOV-fatalities (n = 6). Statistical analysis was performed by using Mann Whitney test and differences were considered significant with a p<0.05 and highlighted with an asterisk.*: p<0.05; **: p<0.01; ***: p<0.001.</p

Visual mismatch negativity to vanishing parts of objects in younger and older adults.

We investigated visual mismatch negativity (vMMN) to vanishing parts of continuously present objects by comparing the event-related potentials (ERPs) to infrequently (deviant) and frequently (standard) disappearing parts of the objects. This paradigm both excludes low-level stimulus-specific adaptation differences between the responses to deviants and standards, and increases the ecological validity of the stimuli. In comparison to frequently disappearing parts of the stimulus objects, infrequently vanishing parts elicited posterior negative event-related brain activity (vMMN). However, no vMMN emerged to the reappearance of the same parts of the objects. We compared the ERPs of an older and a younger sample of participants. In the 120-180 ms time period vMMN was similar in the two age groups, but in the 180-220 ms time period vMMN emerged only in the younger participants. We consider this difference as an index of more elaborate automatic processing of infrequent stimulus changes in younger adults