Biology subjects

Maestri, A.

Publications and source records attributed to Maestri, A..

8 recordsLinked to original sources

bioRxiv2026

Early Immune Hypoactivation and Persistent Innate Reprogramming Characterize Chronic Chikungunya Disease

Chikungunya virus (CHIKV) infection causes acute febrile illness and debilitating arthralgia, with up to 40-80% of patients developing chronic chikungunya disease characterized by persistent arthralgia and fatigue lasting months to years. The immunological mechanisms underlying this transition remain poorly understood. We performed longitudinal immune profiling of CHIKV-infected patients stratified by clinical outcome. Single-cell RNA sequencing of peripheral blood mononuclear cells collected during acute infection and six months post-infection was combined with multiplex plasma cytokine and flow cytometric analysis. Patients who later developed chronic symptoms were characterized by early innate immune hypoactivation during acute infection, characterized by reduced monocyte and dendritic cell frequencies, lower circulating IFN-, IL-6 and IL-8, and reduced antigen-presentation and interferon-associated transcriptional programs. This was accompanied by diminished adaptive immune activation, including reduced IL-17 and IL-21 and lower HLA-DR expression across multiple T-cell subsets. Cell-cell communication analysis further indicated impaired acute monocyte-centered immune coordination in chronic progressors, whereas non-chronic patients displayed stronger monocyte-driven innate-to-adaptive signaling. By six months, chronic patients showed persistent innate remodeling, including increased non-classical monocytes, altered plasmacytoid dendritic cell and natural killer cell transcriptional programs, elevated CXCL10, reduced IL-6 and MMP8, and emergence of NK-centered predicted communication networks. Longitudinal transcriptomic analysis further identified divergent immune recovery trajectories, most prominently in non-classical monocytes and plasmacytoid dendritic cells. Together, these findings suggest that chronic chikungunya disease is associated with early innate immune hypoactivation followed by persistent innate immune remodeling, providing insight into immune mechanisms that may contribute to post-viral chronic inflammatory syndromes.

immunology↗

bioRxiv2026

Oncogenic ERK signaling represses chaperone-mediated autophagy through transcriptional control of LAMP-2A

Chaperone-mediated autophagy (CMA) is a selective lysosomal degradation pathway governed by the rate-limiting receptor LAMP-2A and increasingly implicated in cancer. However, the oncogenic circuits that enforce CMA repression and whether this state is therapeutically reversible remain unclear. Here, we developed a quantitative bioluminescence-based reporter to measure CMA activity in human cancer cells and combined parallel chemical and genome-scale CRISPR-Cas9 screens to define regulatory pathways. The chemical screen identified GSK1059615 as a CMA-restoring compound that increased LAMP-2A transcription and protein abundance in vitro and in vivo. In parallel, the CRISPR screen revealed ERK signaling as a pathway-level suppressor of CMA. Genetic or pharmacologic ERK inhibition de-repressed LAMP-2A expression, while integrated modulation of ERK, PI3K-AKT, and p38 signaling coordinated transcriptional induction and stabilization of LAMP-2A. Transcriptomic analyses further implicated FOXO1/FOXP1-driven programs in LAMP-2A regulation. Together, these findings position CMA as an integrated output of oncogenic signaling networks and establish a mechanistic framework for restoring CMA activity in defined cancer contexts.

cell biology↗

bioRxiv2026

Rapid modular evolution of antiviral repertoires in P2 phages and their P4 satellites: shuttling, swapping and mixing

Interactions between bacteria, bacteriophages, and their satellites are shaped by a myriad of defence and counter-defence mechanisms. Here, we identified and characterized the defence hotspots of thousands of P2-like phages and P4-like satellites to elucidate the origins and evolutionary dynamics of defence systems. Both P4 and P2 encode a broad diversity of recognizable defence systems. Defences are a substantial, yet likely underestimated, share of the elements pangenomes, as shown by novel antiviral functions discovered in P4 loci lacking known defence genes. Defence loci are very rapidly swapped, without pseudogenization, suggesting defences are replaced before becoming non-adaptive. This intense local recombination melds components of distinct systems into novel functional chimeras. Systems swap so rapidly that many elements with identical core genes have completely different defences. Surprisingly, despite P4 and P2s concomitant replication and packaging, they almost never exchange defence genes. In contrast, near identical defence systems can be found in distinct types of MGEs and in cryptic chromosomal locations. Our findings highlight P4 and P2 as mobile platforms driving the modular diversification of bacterial antiviral repertoires. Hence, bacterial defences change quickly by phage and satellite turnover, and by the quick swap of defences within these elements.

microbiology↗

bioRxiv2024

Titration-WB: A methodology for accurate quantitative protein determination overcoming reproducibility errors

Western blot (WB) technique is widely used to identify and quantify proteins in biological samples, but it is poorly accurate and precise for quantitative purposes. Merging the WB with the titration assay, we established a reliable method for protein quantification based on the slope of the linear function for signal-intensity/total protein loaded. Titration-WB unravels systematic and operator errors, compensates for problems in antibody affinity/avidity, and permits trustworthy inter-WB comparison.

biochemistry↗

bioRxiv2024

Adipose tissue microvascular endothelial cells form a tight vascular barrier that selectively transcytoses fatty acid tracers

In organs with continuous, non-leaky capillaries like white adipose tissue and the heart, microvascular endothelial cells (ECs) serve as a vital barrier, facilitating nutrient delivery to underlying tissues. While capillary heterogeneity between organs is well established, how these vascular layers have adapted their key functions - such as fatty acid transport - to their respective organs remains unclear, largely due to the lack of organotypic endothelial model systems. Here we demonstrate that the vascular barrier in white adipose tissue, a crucial organ for whole-body fatty acid handling, exhibits comparable impermeability to that of heart and muscle. To investigate if the adipose endothelium possesses tissue-specific functions for facilitating fatty acid transport, we developed an in vitro dual tracing-system that allows simultaneous monitoring of barrier integrity and fatty acid transport dynamics by modifying the classic transwell culture. Using this system, we can show human adipose-derived primary ECs selectively transport fluorescent fatty acid tracers while excluding other tracers like dextrans, a phenomenon not observed in other cultured human ECs. Additionally, our findings reveal EC-type specific responses to various transcytosis inhibitors. Our results underscore the unique characteristics of the adipose endothelium and enhances our understanding of how microvascular permeability and transport dynamics have adapted to their specific organ physiology.

cell biology↗

bioRxiv2023

Bacterial defences interact synergistically by disrupting phage cooperation

The constant arms race between bacteria and their phages has resulted in a large diversity of bacterial defence systems1,2, with many bacteria carrying several systems3,4. In response, phages often carry counter-defence genes5-9. If and how bacterial defence mechanisms interact to protect against phages with counter-defence genes remains unclear. Here, we report the existence of a novel defence system, coined MADS (Methylation Associated Defence System), which is located in a strongly conserved genomic defence hotspot in Pseudomonas aeruginosa and distributed across Gram-positive and Gram-negative bacteria. We find that the natural co-existence of MADS and a Type IE CRISPR-Cas adaptive immune system in the genome of P. aeruginosa SMC4386 provides synergistic levels of protection against phage DMS3, which carries an anti-CRISPR (acr) gene. Previous work has demonstrated that Acr-phages need to cooperate to overcome CRISPR immunity, with a first sacrificial phage causing host immunosuppression to enable successful secondary phage infections10,11. Modelling and experiments show that the co-existence of MADS and CRISPR-Cas provides strong and durable protection against Acr-phages by disrupting their cooperation and limiting the spread of mutants that overcome MADS. These data reveal that combining bacterial defences can robustly neutralise phage with counter-defence genes, even if each defence on its own can be readily by-passed, which is key to understanding how selection acts on defence combinations and their coevolutionary consequences.

microbiology↗

bioRxiv2021

Robust and Functional Immunity up to 9 months after SARS-CoV-2 infection: a Southeast Asian longitudinal cohort

Assessing the duration of humoral and cellular immunity remains key to overcome the current SARS-CoV-2 pandemic, especially in understudied populations in least developed countries. Sixty-four Cambodian individuals with laboratory-confirmed infection with asymptomatic or mild/moderate clinical presentation were evaluated for humoral immune response to the viral spike protein and antibody effector functions during acute phase of infection and at 6-9 months follow-up. Antigen-specific B cells, CD4+ and CD8+ T cells were characterized, and T cells were interrogated for functionality at late convalescence. Anti-spike (S) antibody titers decreased over time, but effector functions mediated by S-specific antibodies remained stable. S- and nucleocapsid (N)-specific B cells could be detected in late convalescence in the activated memory B cell compartment and are mostly IgG+. CD4+ and CD8+ T cell immunity was maintained to S and membrane (M) protein. Asymptomatic infection resulted in decreased ADCC and frequency of SARS-CoV-2-specific CD4+ T cells at late convalescence. Whereas anti-S antibodies correlated with S-specific B cells, there was no correlation between T cell response and humoral immunity. Hence, all aspects of a protective immune response are maintained up to nine months after SARS-CoV-2 infection in the absence of re-infection. One sentence summaryFunctional immune memory to SARS-CoV-2, consisting of polyfunctional antibodies, memory B cells and memory T cells are maintained up to nine months in a South-East Asian cohort in the absence of re-infection.

immunology↗

bioRxiv2019

Exploitation of the cooperative behaviours of anti-CRISPR phages

Many bacteria encode CRISPR-Cas (Clustered Regularly Interspaced Short Palindromic Repeats; CRISPR-associated) adaptive immune systems to protect themselves against their viruses (phages)1. To overcome resistance, phages have evolved anti-CRISPR proteins (Acr), which naturally vary in their potency to suppress the host immune system and avoid phage extinction2,3,4,5. However, these Acr-phages need to cooperate in order to overcome CRISPR-based resistance4,5: while many initial infections by Acr-phages are unsuccessful, they nonetheless lead to the production of Acr proteins, which generate immunosuppressed cells that can be successfully exploited by other Acr-phages in the population4,5. Here we test the prediction that phages lacking acr genes (Acr-negative phages) may exploit this cooperative behaviour6. We demonstrate that Acr-negative phages can indeed benefit from the presence of Acr-positive phages during pairwise competitions, but the extent of this exploitation depends on the potency of the Acr protein. Specifically, \"strong\" Acr proteins are more exploitable and benefit both phage types, whereas \"weak\" Acr proteins predominantly benefit Acr-positive phages only and therefore provide a greater fitness advantage during competition with Acr-negative phages. This work further helps to explain what defines the strength of an Acr protein, how selection acts on different Acr types in a phage community context, and how this can shape the dynamics of phage populations in natural communities.

microbiology↗