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Biology subjects

Melero, I.

Publications and source records attributed to Melero, I..

8 recordsLinked to original sources

Orsay virus infection is associated with reduced locomotion and alters cue-dependent food choice in Caenorhabditis elegans

Behavioral responses are an important component of host defense; however, most evidence in Caenorhabditis elegans comes from bacterial pathogens. Here, we tested whether infection with Orsay virus (OrV) alters host dispersal and food choice and whether these responses involve the RNA-processing factor EOL-1. When measuring distance travelled over a certain period of time in control and infected wild-type animals, we observed that OrV infection was associated with lower locomotion. Moreover, when presenting infected and control animals with food choices, we observed that infected animals preferred OrV infected food sources only when the alternative was a pure food source, preferring a non-inoculated food source when both control and viral food sources contained a C. elegans filtrate. Moreover, loss of EOL-1 altered baseline locomotion and attenuated the infection-associated reduction detected in the earlier motility assay, while also modifying the food choice response, suggesting that eol-1 contributes to the motility and behavioral changes induced by OrV infection. Collectively, these results support an overall association between OrV infection and reduced host dispersal, whereas its effect on food choice depends on the sensory context. These findings extend infection-associated behavioral responses to a natural viral pathogen and identify eol-1 as a modulator of their expression.

microbiology↗

Replication competent adenoviral platform for in situ production of immunotherapeutic RNA aptamers targeting 4 1BB

Viroimmunotherapy leverages oncolytic viruses to induce antitumor immunity and is increasingly explored for solid tumors. Their activity can be enhanced by arming them with immunostimulatory payloads, but most approaches rely on protein-based transgenes that are constrained by viral genome packaging limits. Here, we establish a replication-competent Delta-24-RGD-based platform for localized production of immunotherapeutic RNA aptamers at the tumor site. RNA aptamers provide compact, highly specific ligands that can, in principle, target diverse immune receptors. As a model, we engineered a Delta-24-RGD derivative encoding circular 4-1BB targeting aptamers and show that infected tumor cells sustain aptamer transcription and release, which is associated with a pro-inflammatory remodeling of the tumor microenvironment and measurable antitumor activity in different mouse models with a comparable effect to that achieved with a 4-1BBL-expressing adenovirus used as a benchmark. Overall, this work delivers a proof of concept that replication-competent adenoviruses can serve as in situ factories for extracellularly active RNA aptamers, supporting their development as flexible platforms for localized non-coding cancer immunotherapy.

cancer biology↗

Hiltonol and Protamine-RNA stimulation induce an immune-activating transcriptome profile in cDC1s

Ex-vivo stimulation of dendritic cells (DCs) is a critical step in DC-based cancer immunotherapies. In humans, conventional type 1 dendritic cells (cDC1s) are a rare myeloid dendritic cell (mDC) subset that express BDCA-3 (CD141). cDC1s promote CD8+ T cell cross-priming against tumor antigens and are therefore being explored for use in immunotherapy. We evaluated the impact of ex-vivo stimulation on human peripheral blood cDC1s. In contrast to routine evaluation, which focuses on pre-defined surface maturation markers or soluble factors released from the activated cells, we investigated the impact of stimulation on the transcriptome using both RNA-sequencing (RNA-seq) and microarrays. Specifically, we analyzed the mRNA of cDC1s upon activation with two clinical-grade adjuvants, Hiltonol (poly IC, a TLR3 ligand) and protamine-stabilized RNA (pRNA, a TLR7/8 ligand) compared to unstimulated controls. Both RNA-seq and microarray analysis showed profound and similar effects of both Hiltonol and pRNA on the transcriptome of cDC1s. A gene ontology (GO) analysis suggested that these changes were mainly related to activation and maturation pathways, including induction of type-I interferon (IFN) and interleukin (IL)-12 transcription, while pathways related to adverse effects or cell damage did not appear to be affected. Combination of both reagents did not appear to have a synergistic effect, as the transcriptome changes were similar to those induced by each stimulus alone. Together, our results indicate that both adjuvants have comparable effects on cDC1 maturation within an immunogenic short-term culture as performed in immunotherapy.

immunology↗

The interplay between Caenorhabditis elegans larval development and Orsay virus infection

Caenorhabditis elegans development can be altered by its interactions with pathogens, such as bacteria1,2 or fungi3. However, the impact of viral infections on the nematodes development remains largely unexplored, and conversely, whether molting periods affect viral replication is unknown. Studying infections with Orsay virus (OrV), the only known natural C. elegans virus4, we investigated the role of molting on virus replication dynamics and the impact of OrV infection on C. elegans larval development. We found that OrV replicates during C. elegans molting periods. Indeed, nematodes inoculated near molt initiation exhibited higher OrV viral loads and the virus infected more intestinal cells. Moreover, nematodes inoculated right after hatching accelerated the start of the first molt and lengthened the second larval stage, effectively resynchronizing normal developmental timing. Overall, our work enhances understanding of OrV dynamics in C. elegans and elucidates the interplay between viral infection and nematode development. HIGHLIGHTSO_LIrsay virus replication peaks during molting periods, with larvae acquiring virus later in the first larval stage producing higher viral loads and more widespread intestinal infection than larvae acquiring it right after hatching. C_LIO_LIinfection alters the expression of key developmental regulators, particularly those with oscillatory profiles synchronized with molting cycles (such as let-7, lin-42 and nhr-23). C_LIO_LInematodes display temporal plasticity in development: accelerating the first molt while extending the second larval stage, ultimately resynchronizing their developmental timeline. C_LIO_LIis a bidirectional interaction between Orsay virus infection and C. elegans development: molting appears to transiently weaken antiviral defenses, while host development adapts to infection through temporal plasticity. C_LI

microbiology↗

Chromosomal instability shapes the tumor microenvironment of esophageal adenocarcinoma via a cGAS-chemokine-myeloid axis

Chromosomal instability (CIN), a characteristic feature of esophageal adenocarcinoma (EAC), drives tumor aggressiveness and therapy resistance, presenting an intractable problem in cancer treatment. CIN leads to constitutive stimulation of the innate immune cGAS-STING pathway, which has been typically linked to anti-tumor immunity. However, despite the high CIN burden in EAC, the cGAS- STING pathway remains largely intact. To address this paradox, we developed novel esophageal cancer models, including a CIN-isogenic model, discovering myeloid-attracting chemokines - with the chemokine CXCL8 (IL-8) as a prominent hit - as conserved CIN-driven targets in EAC. Using high-resolution multiplexed immunofluorescence microscopy, we quantified the extent of ongoing cGAS-activating CIN in human EAC tumors by measuring cGAS-positive micronuclei in tumor cells, validated by orthogonal whole-genome sequencing-based CIN metrics. By coupling in situ CIN assessment with single-nucleus RNA sequencing and multiplex immunophenotypic profiling, we found tumor cell-intrinsic innate immune activation and intratumoral myeloid cell inflammation as phenotypic consequences of CIN in EAC. Additionally, we identified increased tumor cell-intrinsic CXCL8 expression in CINhigh EAC, accounting for the inflammatory tumor microenvironment. Using a novel signature of CIN, termed CINMN, which captures ongoing CIN-associated gene expression, we confirm poor patient outcomes in CINhigh tumors with signs of aberrantly rewired cGAS-STING pathway signaling. Together, our findings help explain the counterintuitive maintenance and expression of cGAS-STING pathway components in aggressive, CINhigh tumors and emphasize the need to understand the contribution of CIN to the shaping of a pro-tumor immune landscape. Therapeutic strategies aimed at disrupting the cGAS-driven inflammation axis may be instrumental in improving patient outcomes in this aggressive cancer.

cancer biology↗

Within-host virus spreading and tolerance to infection are key factors of the Arabidopsis thaliana age-dependent susceptibility to viral infections

Arabidopsis thaliana is more susceptible to certain viruses during its later developmental stages. The reasons for this age-dependent susceptibility are not fully understood. Here we explored the possible causes by studying the A. thaliana infection response to turnip mosaic virus at three developmental stages: vegetative, bolting and flowering. We found that infected plants at later stages downregulate cell wall fortification genes and that this downregulation facilitates the viral spread and systemic infection. Despite being more susceptible to infection, infected flowering plants are more fertile (i.e., produce more viable seeds) than vegetative and bolting infected plants; that is, they have greater fitness than plants infected at these earlier developmental stages. Treatment of postbolting plants with salicylic acid increases resistance to infections at the cost of significantly reducing fertility. Together, these observations suggest a negative trade-off between viral susceptibility and plant fertility. Our findings point towards a development-dependent tolerance to infection.

microbiology↗

Host age-dependent evolution of a plant RNA virus

Viruses are obligate pathogens that entirely rely on their host resources to complete their infectious cycle. The availability of such resources depends upon external and internal factors, being host age one of the most relevant ones. The interplay between host age and virus evolution has not been thoroughly studied in plants. Here, we have used the Arabidopsis thaliana - turnip mosaic virus (TuMV) pathosystem to study plant-virus interactions and virus evolution at three different host ages: vegetative (juvenile), bolting (transition) and reproductive (mature) stages. After infecting plants with a naive and a well-adapted TuMV isolates, we observed that the older the host the faster and more severe the infections were. The same trend was observed for several other viruses. Thereafter, we experimentally evolved lineages of the naive and the well-adapted TuMV isolates in plants from each of the three developmental stages. All evolved viruses enhanced their infection phenotypes, being this increase more intense on viruses evolved in younger hosts. The genomic changes of the evolved viral lineages revealed mutation patterns that strongly depended on the founder viral isolate as well as on the age of the host wherein the lineages evolved.

evolutionary biology↗

Spatial transcriptomic characterization of COVID-19 pneumonitis identifies immune pathways related to tissue injury

Severe lung damage in COVID-19 involves complex interactions between diverse populations of immune and stromal cells. In this study, we used a spatial transcriptomics approach to delineate the cells, pathways and genes present across the spectrum of histopathological damage in COVID-19 lung tissue. We applied correlation network-based approaches to deconvolve gene expression data from areas of interest within well preserved post-mortem lung samples from three patients. Despite substantial inter-patient heterogeneity we discovered evidence for a common immune cell signaling circuit in areas of severe tissue that involves crosstalk between cytotoxic lymphocytes and pro-inflammatory macrophages. Expression of IFNG by cytotoxic lymphocytes was associated with induction of chemokines including CXCL9, CXCL10 and CXCL11 which are known to promote the recruitment of CXCR3+ immune cells. The tumour necrosis factor (TNF) superfamily members BAFF (TNFSF13B) and TRAIL (TNFSF10) were found to be consistently upregulated in the areas with severe tissue damage. We used published spatial and single cell SARS-CoV-2 datasets to confirm our findings in the lung tissue from additional cohorts of COVID-19 patients. The resulting model of severe COVID-19 immune-mediated tissue pathology may inform future therapeutic strategies. One Sentence SummarySpatial analysis identifies IFN{gamma} response signatures as focal to severe alveolar damage in COVID-19 pneumonitis.

immunology↗