Biology subjects

Carrasco, S.

Publications and source records attributed to Carrasco, S..

7 recordsLinked to original sources

bioRxiv2026

Lipogenesis-driven EGFR palmitoylation enables metastatic immune evasion in triple-negative breast cancer.

Metastasis is the leading cause of death in triple-negative breast cancer (TNBC), yet how tumor cells evade immune recognition during dissemination remain unclear. Here, we show that de novo lipogenesis drives metastatic immune evasion through FASN-mediated palmitoylation of EGFR. This modification establishes a lipid-dependent membrane signaling scaffold that sustains PI3K-AKT-mTOR signaling independently of MAPK compensation, thereby suppressing MHC-I antigen presentation through post-translational regulation. As a result, metastatic-competent cells escape CD8+ T cell surveillance and colonize distant organs. Genetic or pharmacologic inhibition of fatty acid synthase (FASN), or expression of palmitoylation-deficient EGFR mutants restores MHC-I surface expression, unleashes robust CD8 T cell activation, and markedly impairs lung metastasis without affecting primary tumor growth. This lipid-dependent EGFR-PI3K-mTOR axis operates independently of MAPK signaling and is not rescued by exogenous lipids, revealing a non-redundant metabolic dependency. Our results identify FASN-driven EGFR palmitoylation as a tumor-intrinsic immunometabolic checkpoint that couples lipid metabolism to antigen-presentation and metastatic competence. Targeting this pathway with clinically advancing FASN inhibitors offers a promising strategy to suppress metastasis by restoring anti-tumor immunity in TNBC.

cancer biology↗

bioRxiv2025

Injectable adhesive hydrogel-drug complexes synchronize the release of chemoimmunotherapy to treat brain tumors in mice

Brain tumor therapy remains limited by an immunosuppressive, monotherapy-resistant tumor microenvironment and by a paucity of technologies capable of controlling therapy delivery kinetics to the tumor. Here, we describe tissue-adhesive hydrogel-drug complexes (HDCs) for the controlled release of combination therapies synchronized with immune cycle responses following intracranial administration. Injected adhesive HDCs enabled the controlled co-delivery of multiple payloads (chemotherapy, stimulator of interferon genes agonist cyclic dinucleotide nanoparticles, immune checkpoint blockade antibodies), leading to enhanced long-term survival (>80%) and protection from contralateral hemisphere rechallenge after a single dose in multiple syngeneic orthotopic glioblastoma mouse models. Mechanistic studies revealed that tumor rejection is a consequence of reprogramming the tumor microenvironment, driven by three key phases: the initial rapid expression of inflammatory cytokines, notably IFN-{gamma}, and tumor sensitization with antigen exposure during chemoimmunotherapy release, followed by the recruitment and subsequent sustained activation of antigen-presenting and effector cells facilitated by the hydrogels multiweek delivery period. These findings point to tissue-adhesive HDCs, and therapeutic release synchronized with biological responses as key considerations for realizing robust immune activation without provoking toxicity in the treatment of solid tumors.

bioengineering↗

bioRxiv2025

Zebrafish armc9 mutant reveals a link between ARM-Type fold domain loss, inflammation, and spinal curvature

The vertebral column (VC) defines the central axis of vertebrates. Among its malformations, adolescent idiopathic scoliosis (AIS) is the most common, characterized by lateral spine curvature without congenital abnormalities. While its etiology remains elusive, genetic studies in zebrafish have linked AIS to skeletogenesis, cilia structure, cerebrospinal fluid flow, and inflammation. In this study, we characterized the zebrafish armc9 mutant, exhibiting AIS-like curvature without vertebral malformations, subcommissural organ, or Reissner fiber structure disruptions. We also detected an inflammatory response at the curvature origin. Structural bioinformatics and molecular docking analyses suggest that the mutant Armc9 protein partially lacks the functional ARM-type fold domain, which is crucial for its interaction with Togaram1, revealing that both proteins are relevant for ciliary signaling and spine curvature. Phylogenetic analyses indicate that the ARMC gene family encompasses 12 members, highlighting that the Armc9 gene has deep evolutionary roots. Our results demonstrate that the zebrafish armc9 mutant accurately represents the AIS phenotype, suggesting that the loss of Armc9s C-terminal ARM-type fold domain could affect the ciliary integrity and contribute to spine curvature by altering the skeletogenic environment. Taken together, this study proposes that the zebrafish armc9 mutant offers a unique opportunity to understand the etiology of AIS and provides new insights into the molecular interaction networks of Armc9 in ciliary signaling.

developmental biology↗

bioRxiv2024

Assessing the Biosecurity Risk of Footwear as a Fomite for Transmission of Adventitious Infectious Agents to Mice

The soles of staff shoes accessing vivaria can become contaminated on urban streets, potentially serving as a source of fomite-mediated transmission of adventitious agents to laboratory rodents. While shoe covers may mitigate this risk, donning them can lead to hand contamination. Staff accessing our vivaria use motor-driven shoe cleaners hundreds of times daily to remove and collect particulates via a vacuum collection system from the top, sole, and sides of shoes instead of shoe covers. Shoe cleaner debris (SCD) and contact media (CM) exposed to SCD from shoe cleaners in 5 vivaria were assessed by PCR for 84 adventitious agents. SCD and CM samples tested positive for 33 and 37 agents, respectively, and a combined 39 agents total. To assess SCD infectivity, NSG and Swiss outbred mice were housed for 7 days in direct contact with SCD and oronasally inoculated with a suspension created from SCD collected from each of the 5 vivaria. Mice were tested by PCR and serology 3-, 7-, 14- and 63-days post-inoculation. All mice remained healthy until the studys end and tested negative for all agents found in SCD/CM except murine astrovirus 1, Staphyloccocus xylosus and Candidatus Savagella, agents known to be enzootic in the experimental mouse source colony. In a follow-up study, the soles of 27 staff street shoes were directly sampled using CM. Half of CM was used for PCR, while the other half was added as bedding material to a cage containing NSG and Swiss outbred mice. While CM tested positive for 11 agents, all mice were healthy 63 days post-exposure and again positive for only enzootic agents. These results suggest that shoe debris might not be a significant biosecurity risk to laboratory mice, questioning the need for shoe covers or cleaners when entering experimental barrier vivaria.

microbiology↗

bioRxiv2024

Assessment of Antimicrobial Therapy in Eradicating Chlamydia muridarum in Research Mice: Immune Status and its Impact on Outcomes

Chlamydia muridarum (Cm) is a moderately prevalent, gram-negative, intracellular bacterium that affects laboratory mice, causing subclinical to severe disease, depending on the hosts immune status. The effectiveness of various antibiotic regimens aimed at eradicating Cm in both immunodeficient and immunocompetent laboratory mice was evaluated. NSG mice were cohoused with Cm-shedding BALB/cJ mice for 14 days to simulate natural exposure. Four groups of 8 infected NSG mice were treated for 7 days with either 0.08% sulfamethoxazole and 0.016% trimethoprim (TMS) in water, 0.0625% doxycycline in feed, 0.124%/0.025% TMS in feed, or 0.12% amoxicillin in feed. A control group was provided standard water and feed. The impact of treatment on gastrointestinal microbiota (GM) was performed using next-generation shotgun sequencing on the last day of treatment. TMS and Amoxicillin had negligible effects on GM, while doxycycline had the largest effect. All antibiotic treated NSG mice exhibited clinical disease, including dehydration, hunched posture, >20% weight loss, and dyspnea, leading to euthanasia 21-40 days post-treatment (32.6 {+/-} 4.2 days; mean {+/-} SD). Untreated controls were euthanized 14-33 days post-exposure (23.75 {+/-} 5.9 days). All mice were fecal PCR positive for Cm at euthanasia. Histological evaluation revealed multifocal histiocytic and neutrophilic bronchointerstitial pneumonia and/or bronchiolitis featuring prominent intralesional chlamydial inclusion bodies in all mice. Subsequently, groups of 8 C57BL/6J, BALB/cJ, NOD.SCID, and NSG mice infected with Cm were treated with 0.124%/0.025% TMS in feed for 7 (BALB/cJ and C57BL/6J) or 21 days (NSG and NOD.SCID). All immunocompetent and NOD.SCID mice were negative for Cm by PCR 14 days post-treatment, remained clinically normal and had no evidence of Cm infection at necropsy, all NSG mice remained Cm positive and were euthanized. While these findings highlight the difficulties in eradicating Cm from highly immunodeficient mice, eradication of Cm from immunocompetent or moderately immunocompromised mice with antibiotics is feasible.

pharmacology and toxicology↗

bioRxiv2024

EARLY NEUTROPHIL ACTIVATION AND NETs RELEASE IN THE PRISTANE-INDUCED LUPUS MICE MODEL

BackgroundNETosis is recognized as an important source of autoantigens. Therefore, we hypothesized whether the pristane-induced lupus mice model shows early activation of neutrophils, the presence of low-density granulocytes (LDGs), and neutrophil extracellular traps (NETs) release, which could contribute to the development of a lupus phenotype. MethodsTwelve female wild-type Balb/c mice were intraperitoneally injected with pristane (n=6; pristane group) or saline (n=6; control group). Five days after the injection, blood, peritoneal lavage, bone marrow, and spleen samples were collected for flow cytometry analyses of activated neutrophils (Ly6G+CD11b+), LDGs (CD15+CD14low), and NETs release (Sytox Green+). ResultsThe pristane-induced mice group had a significantly increased number of blood activated neutrophils and LDGs as well as NETs released by these cells compared to the saline-injected control group and the basal values determined 12 days before the injection. The pristane group also had a significantly increased number of activated neutrophils, LDGs, and NETs released compared to the control group for the peritoneal lavage, bone marrow, and spleen. ConclusionsWe demonstrated early changes in the innate immune response such as an increased number of activated neutrophils and LDGs and mainly increased NETosis in the pristane-induced mice model which may be considered as the primary event triggering lupus development.

immunology↗

bioRxiv2022

Reemergence of the Murine Bacterial Pathogen Chlamydia muridarum in Laboratory Mouse Colonies

Chlamydia muridarum (Cm) was detected in mice from 2 colonies with lymphoplasmacytic pulmonary infiltrates using PCR and immunohistochemistry. This discovery was unexpected as Cm infection had not been reported in laboratory mice since the 1940s. A Cm specific PCR assay was developed and testing implemented for resident colonies from 8 vivaria from 3 academic institutions, 58 incoming mouse shipments from 39 academic institutions, and mice received from 55 commercial breeding colonies (4 vendors). To estimate Cms global prevalence in laboratory colonies, a database containing 11,387 metagenomic fecal microbiota samples from 120 institutions and a cohort of 900 diagnostic samples from 96 institutions were examined. Results indicate significant prevalence amongst academic institutions with Cm detected in 62.9% of soiled bedding sentinels from 3 institutions; 32.7% of incoming mouse shipments from 39 academic institutions; 14.2% of 120 institutions submitting microbiota samples; and 16.2% of the diagnostic sample cohort. All samples from commercial breeding colonies were negative. Additionally, naive NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice exposed to Cm shedding mice and their soiled bedding developed clinical disease 21 to 28 days following exposure. These mice had a moderate-to-severe histiocytic and neutrophilic bronchointerstitial pneumonia with respiratory epithelium demonstrating inclusions, chlamydial major outer membrane protein immunostaining, and hybridization with a Cm reference sequence (GenBank accession no. U68436). Cm was isolated on HeLa 229 cells from lungs, cecum, and feces of a Cm infected NSG mouse. The considerable prevalence of Cm is likely attributed to widespread global interinstitutional distribution of unique mouse strains and failure to recognize that some of these mice were from enzootically infected colonies. Given that experimental Cm colonization of mice results in a robust immune response and, on occasion, pathology, natural infection may confound experimental results. Therefore, Cm should be excluded and eradicated from endemically infected laboratory mouse colonies.

microbiology↗