Biology subjects

Aranda, C.

Publications and source records attributed to Aranda, C..

5 recordsLinked to original sources

bioRxiv2023

The memory of pathogenic IgE is contained within CD23+IgG1+ memory B cells poised to switch to IgE in food allergy

Food allergy is caused by allergen-specific IgE antibodies but little is known about the B cell memory of persistent IgE responses. Here we describe in human pediatric peanut allergy CD23+IgG1+ memory B cells arising in type 2 responses that contain peanut specific clones and generate IgE cells on activation. These type2-marked IgG1+ memory B cells differentially express IL-4/IL-13 regulated genes FCER2/CD23, IL4R, and germline IGHE and carry highly mutated B cell receptors (BCRs). Further, high affinity memory B cells specific for the main peanut allergen Ara h 2 mapped to the population of type2-marked IgG1+ memory B cells and included convergent BCRs across different individuals. Our findings indicate that CD23+IgG1+ memory B cells transcribing germline IGHE are a unique memory population containing precursors of pathogenic IgE. One-Sentence SummaryWe describe a unique population of IgG+ memory B cells poised to switch to IgE that contains high affinity allergen-specific clones in peanut allergy.

immunology↗

bioRxiv2022

Spatial scale influences taxon conservation in the eukaryotic virome of a mosquito

Our knowledge on the diversity of eukaryotic viruses has recently undergone a massive expansion. This diversity could influence host physiology through yet unknown phenomena of potential interest to the fields of health and food production. However, the assembly processes in eukaryotic viromes of terrestrial animals remain elusive. This situation hinders hypothesis-driven tests of virome influence on host physiology. Here, we explore virome assembly at different spatial scales in the eukaryotic virome of the mosquito Culex pipiens. This mosquito is a vector of human pathogens worldwide. Several new aspects of virome assembly were unveiled through a sampling involving five countries in Africa and Europe and large sample sizes. A group of viruses was conserved in C. pipiens populations in all countries. This core group represented a relatively large and diverse fraction of the virome. However, core viruses were not shared by all host individuals in a given country, and their infection rates fluctuated between countries and years. Moreover, the distribution of co-infections in individual mosquitoes suggested random co-occurrence of certain core viruses. We also observed differences in the virome depending on geography, with viromes tending to cluster depending on the continent. Thus, our results unveil that taxon conservation in a eukaryotic virome changes with spatial scale. Thus, predictions on virome assembly seem possible at a large geographical scale in C. pipiens. IMPORTANCEThe study of the eukaryotic virome of mosquitoes is an emerging research field. Beyond its fundamental interest, this field could lead to the development of control tools against the transmission of mosquito-borne human pathogens. However, we yet know little on the assembly patterns in the eukaryotic viromes of mosquitoes, as well as of terrestrial animals in general. This situation hampers the design of hypothesis-driven studies on the influence of the virome on pathogen transmission. Here, we have analyzed virome assembly in the mosquito vector Culex pipiens within and between countries in Africa and Europe. Our results show that integrating contrasted spatial scales allows to identify deterministic patterns in virome assembly. Such patterns can guide future studies of virome influence on mosquito physiology.

ecology↗

bioRxiv2022

Biphasic release propensity of mucin granules is supervised by TSPAN8

Agonist-mediated stimulated pathway of mucin and insulin release is biphasic in which a rapid fusion of pre-docked granules is followed by slow docking and fusion of granules from the reserve pool. The sustained neurotransmitter release also necessitates docking of vesicles from a reserve pool. We present here a surprising finding that plasma membrane-located tetraspanin-8 (Tspan-8) sequesters syntaxin-2 (Stx2) to control external agonist-dependent mucin release. Tspan-8 specifically affects fusion of granules in reserve during the second phase of stimulated mucin release. The Tspan-8 and Stx2 complex does not contain VAMP-8 and Munc18, which are required for fusion of mucin granules. We suggest that by sequestering Stx2, Tspan-8 prevents docking granules in the reserve pool. In the absence of Tspan-8, granules in reserve pool are free to dock to Stx2 and their fusion doubles the quantities of mucins secreted. Tspan-8 thus emerges as the long-sought component that controls biphasic mucin release. We suggest a similar mechanism likely controls biphasic insulin and sustained neurotransmitter release.

cell biology↗

bioRxiv2020

A litmus test for harmonized mosquito monitoring across Europe and Africa

The accelerating rate of outbreaks from mosquito borne diseases are urging the development of updated and effective tools for the surveillance of insect populations and their larval habitats. Harmonized field protocols help to build a comprehensive picture on species-specific vector ecology and generate important knowledge for implementing coordinated mosquito surveillance programs at regional scales and across continents. In this study, we test the efficiency and potential barriers of available harmonized protocols from earlier EU project VectorNet. As a kind of litmus test for such protocols, we specifically aim to capture the ecoregional variation of breeding site characteristics and population density of five mosquito vectors in Europe and Africa. As expected, the five species considered show different aquatic habitat preferences. Culex pipiens, Aedes albopictus in Europe and Ae. aegypti in Africa select breeding habitats within specific volume classes, while Anopheles gambiae and An. coluzzii may select breeding habitats based on seasonal availability. Population densities in aquatic habitats greatly varied across species and countries, but larval production sites of Ae. albopictus generate populations with higher ratio of pupae compared to the other species. This result underlines the fundamental ecological difference between the selected vector species disregarding of the ecoregion. Mean water temperatures had limited variation across species and higher among countries. Understanding the ecology of native and non-native mosquito vectors is key in evaluating transmission risks for diseases such as West Nile, chikungunya and dengue fevers, zika and malaria. The available harmonized field protocols are a valuable tool for achieving homogeneous mosquito surveillance in Europe and Africa.

ecology↗

bioRxiv2019

Plasmodium vivax Malaria viewed through the lens of an eradicated European strain

The protozoan Plasmodium vivax is responsible for 42% of all cases of malaria outside Africa. The parasite is currently largely restricted to tropical and subtropical latitudes in Asia, Oceania and the Americas. Though, it was historically present in most of Europe before being finally eradicated during the second half of the 20th century. The lack of genomic information on the extinct European lineage has prevented a clear understanding of historical population structuring and past migrations of P. vivax. We used medical microscope slides prepared in 1944 from malaria-affected patients from the Ebro Delta in Spain, one of the last footholds of malaria in Europe, to generate a genome of a European P. vivax strain. Population genetics and phylogenetic analyses placed this strain basal to a cluster including samples from the Americas. This genome allowed us to calibrate a genomic mutation rate for P. vivax, and to estimate the mean age of the last common ancestor between European and American strains to the 15th century. This date points to an introduction of the parasite during the European colonisation of the Americas. In addition, we found that some known variants for resistance to anti-malarial drugs, including Chloroquine and Sulfadoxine, were already present in this European strain, predating their use. Our results shed light on the evolution of an important human pathogen and illustrate the value of antique medical collections as a resource for retrieving genomic information on pathogens from the past.

genetics↗