Biology subjects

Olivares-Villagomez, D.

Publications and source records attributed to Olivares-Villagomez, D..

9 recordsLinked to original sources

bioRxiv2026

Liver-to-Atria Inflammatory Axis Driving Arrhythmia

BackgroundMetabolic dysfunction-associated steatohepatitis (MASH) is emerging as a risk factor of cardiometabolic diseases, including the atrial fibrillation (AF) - the most common sustained arrhythmia. Given that the liver is a major source of inflammatory mediators, lipids, and hepatokines under metabolic stress, we hypothesized that hepatocyte-derived factors in MASH may accelerate atrial remodeling and arrhythmogenesis. MethodsAnalysis of the Atherosclerosis Risk in Communities (ARIC) visit 5 cohort was performed to determine the association between the FIB-4 index - a classic indicator of liver fibrosis, and AF risk, with multivariable adjustment for common comorbidities. A murine model of MASH was induced using the GAN (Gubra-Amylin NASH) diet. Programmed intracardiac stimulation and echocardiography were performed to assess AF susceptibility and cardiac function. Calcium imaging, histology, flow cytometry, plasma proteomics, and single-nucleus RNA sequencing (snRNA-seq) analyses were employed to elucidate the role of recruited inflammatory macrophages via hepatocyte-derived osteopontin (OPN) in MASH-induced atrial remodeling. ResultsAnalysis of the ARIC cohort confirmed a higher cumulative incidence of AF and an elevated adjusted hazard ratio (HR) in patients with intermediate and high FIB-4 indices compared to individuals with low FIB-4 scores. MASH mice exhibited increased susceptibility to pacing-induced AF, accompanied by enhanced proarrhythmic calcium release events, atrial enlargement, and fibrosis, independent of ventricular dysfunction. Proteomics and snRNA-seq revealed that the hepatocyte-secreted OPN under MASH conditions promoted the differentiation and recruitment of TGFBR1+ inflammatory macrophages to the atria, leading to gasdermin D (GSDMD) activation - an effector of inflammasome signaling and consequent proarrhythmic atrial remodeling. Activation of the monocyte-derived pro-inflammatory TGFBR1+ macrophages was dependent on the OPN receptor CD44. Furthermore, the MASH-induced atrial fibroinflammatory milieu and enhanced AF susceptibility were mitigated through several strategies, including hepatocyte-specific Spp1 (encoding OPN) deletion, neutralization of circulating OPN, ablation of CD44 or GSDMD. ConclusionsThese findings establish a pathogenic role of the hepatokine osteopontin in driving activation and recruitment of TGFBR1+ inflammatory macrophages into the atria, leading to proarrhythmic atrial remodeling under MASH. Osteopontin-targeted therapy or GSDMD inhibition prevents AF, indicating a novel therapeutic strategy for liver disease-related atrial arrhythmogenesis. Clinical PerspectiveO_ST_ABSWhat is new?C_ST_ABSO_LIIn the ARIC cohort, metabolic dysfunction-associated steatohepatitis (MASH) is associated with increased risk of atrial fibrillation (AF) after adjusting for common comorbidities. Elevated levels of circulating osteopontin (encoded by SPP1) predict an increased risk of AF in patients with MASH-induced liver fibrosis. C_LIO_LIMASH enhances hepatocyte secretion of osteopontin, leading to expansion of myeloid cells and recruitment of inflammatory macrophages into atria. This liver-to-atrial inflammatory circuit promotes the development of a substrate conducive to AF, which can be attenuated by hepatocyte-specific Spp1 deletion or neutralizing anti-anti-osteopontin antibody treatment to eliminate the mediator, or ablation of inflammasome effector gasdermin D to correct the atrial response. C_LI What are the clinical implications?O_LIOsteopontin may serve as a biomarker for AF in MASH cohorts. C_LIO_LIAnti-osteopontin therapy through neutralizing antibodies may serve as a novel therapeutic strategy for liver disease-related atrial arrhythmia. C_LI

systems biology↗

bioRxiv2026

A novel C57BL/6 mouse model for the study of severe Citrobacter rodentium infection

The study of human enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC) has been limited by the inability of these pathogens to effectively colonize murine models without prior antibiotic treatment. Because it mimics key features of human EPEC and EHEC infection, Citrobacter rodentium, a natural mouse pathogen that colonizes the lower intestine, has become the primary model for investigating these organisms. C57BL/6 mice are most commonly used for C. rodentium research, however, unless they carry specific genetic mutations, they typically develop only mild disease and clear the infection within weeks. As a result, models of severe disease in genetically unmodified hosts are lacking. Here, we describe the development of a non-genetically modified C57BL/6 mouse line with an undisturbed intestinal microbiota, highly susceptible to severe C. rodentium infection. Early infection in these mice was marked by significantly elevated cecal bacterial burdens and tissue pathology. Immune profiling revealed broad reductions in multiple lymphoid subsets, indicating impaired early mucosal activation. Although overall cytokine expression patterns were similar between groups, ceca of susceptible mice exhibited elevated baseline and early post-infection IL-18, as well as increased G-CSF at day 1. Microbiota analyses showed broadly comparable communities with wildtype controls, with some altered groups, such as Lachnospiraceae, Prevotellaceae, Desulfovibrionaceae, and Erysipelotrichaceae. Together, these findings characterize a robust C57BL/6 model that reproducibly develops severe C. rodentium-induced disease. This phenotype is driven by microbiota-associated alterations and impaired early cecal immunity, providing a valuable system for studying host-microbiota interactions in enteric infections.

microbiology↗

bioRxiv2025

The effects of breastmilk-derived osteopontin on the intestinal intraepithelial lymphocyte compartment

Osteopontin is a protein with many physiological roles and is widely expressed by many cell types, tissues, and bodily fluids, including breastmilk. The functions of breastmilk osteopontin are not clearly defined, however, it is known to impact intestinal and brain development in infants. Although it is known that endogenous osteopontin influences the survival of intestinal intraepithelial lymphocytes (IEL)2, the impact of breastmilk osteopontin on developing intestinal immune cells remains unclear. In this report, mouse models lacking expression of osteopontin were used to demonstrate that milk-derived osteopontin is important for the development of IELs, with observed effects in both juvenile and adult mice. These changes are most prevalent in IELs expressing CD8: however, the impact of these alterations is unclear, as mice with disrupted IEL compartments are not more susceptible to DSS-induced colitis or infection by Citrobacter rodentium.

immunology↗

bioRxiv2025

An Anaerobic Pathogen Rewires Host Metabolism to Fuel Oxidative Growth in the Inflamed Gut

To colonize their host and cause disease, enteric pathogens must deploy their virulence factors to establish distinct nutrient niches. How obligate anaerobic pathogens construct nutrient niches in the densely populated large intestine remains poorly understood. Enterotoxigenic Bacteroides fragilis (ETBF) is considered an obligate anaerobic bacterium and has been implicated in inflammation-associated diseases, including colitis and colorectal cancer. Here we show that ETBF uses its virulence factor, Bacteroides fragilis toxin, to reprogram colonic epithelial cell metabolism to colonize the inflamed gut. Bacteroides fragilis toxin activates colonic epithelial signaling and hijacks the host bile acid recycling pathway, inducing a metabolic shift in the epithelium from oxidative phosphorylation to glycolysis. This shift increases local concentrations of lactate and oxygen, nutrients that support an oxidative metabolism in ETBF. These findings reveal an unexpected strategy by which a pathogenic organism, previously considered to be an obligate anaerobic bacterium, generates and exploits an oxidative niche in the inflamed gut.

microbiology↗

bioRxiv2023

Turicibacterales protect mice from severe Citrobacter rodentium infection

One of the major contributors to child mortality in the world is diarrheal diseases, with an estimated 800,000 deaths per year. Many pathogens are causative agents of these illnesses, including the enteropathogenic (EPEC) or enterohemorrhagic (EHEC) forms of Escherichia coli. These bacteria are characterized by their ability to cause attaching and effacing lesions in the gut mucosa. Although much has been learned about the pathogenicity of these organisms and the immune response against them, the role of the intestinal microbiota during these infections is not well characterized. Infection of mice with E. coli requires pre-treatment with antibiotics in most mouse models, which hinders the study of the microbiota in an undisturbed environment. Using Citrobacter rodentium as a murine model for attaching and effacing bacteria, we show that C57BL/6 mice deficient in granzyme B expression are highly susceptible to severe disease caused by C. rodentium infection. Although a previous publication from our group shows that granzyme B-deficient CD4+ T cells are partially responsible for this phenotype, in this report we present data demonstrating that the microbiota, in particular members of the order Turicibacterales, have an important role in conferring resistance. Mice deficient in Turicibacter sanguinis have increased susceptibility to severe disease. However, when these mice are co-housed with resistant mice, or colonized with T. sanguinis, susceptibility to severe infection is reduced. These results clearly suggest a critical role for this commensal in the protection against entero-pathogens.

microbiology↗

bioRxiv2023

Effects of pasteurization on osteopontin levels in human breastmilk and pasteurized breastmilk products

BackgroundOsteopontin (OPN) is an important breastmilk protein involved in infant intestinal, immunological, and brain development. However, little is known about how common milk pasteurization and storage techniques affect this important bioactive protein. MethodsHuman milk osteopontin concentration was measured in single-donor fresh or frozen breastmilk, pooled Holder-pasteurized donor breastmilk, and a shelf-stable (retort pasteurized) breastmilk product by ELISA. Breastmilk samples were pasteurized and/or frozen before measuring osteopontin concentrations. ResultsHolder pasteurization of breastmilk resulted in an [~]50% decrease in osteopontin levels within single-donor samples, whereas pooled donor breastmilk had comparable osteopontin levels to non-pasteurized single-donor samples. Breastmilk from mothers of preterm infants trended toward higher osteopontin concentration than mothers of term infants; however, samples from preterm mothers experienced greater osteopontin degradation upon pasteurization. Finally, freezing breastmilk prior to Holder pasteurization resulted in less osteopontin degradation than Holder pasteurization prior to freezing. ConclusionCommonly used breastmilk pasteurization and storage techniques, including freezing, Holder and retort pasteurization, decrease the levels of the bioactive protein osteopontin in human breastmilk. ImpactO_LIPasteurization of human breastmilk significantly decreases the levels of the bioactive protein osteopontin C_LIO_LIUse of both pasteurization and freezing techniques for breastmilk preservation results in greater loss of osteopontin C_LIO_LIThis study presents for the first time an analysis of osteopontin levels in single-donor pasteurized milk samples C_LI

physiology↗

bioRxiv2020

Granzyme B skews CD4+ T cell differentiation resulting in increased intestinal pathogenicity

CD4+ T cell activation and differentiation are important events that set the stage for proper immune responses. Many factors are involved in the activation and differentiation of T cells, and these events are tightly controlled to prevent unwanted and/or exacerbated immune responses that may harm the host. It has been well documented that granzyme B, a potent serine protease involved in cell-mediated cytotoxicity, is readily expressed by certain CD4+ T cells, such as regulatory T cells and CD4+CD8+ intestinal intraepithelial lymphocytes, both of which display cytotoxicity associated with granzyme B. However, because not all CD4+ T cells expressing granzyme B are cytotoxic, additional roles for this protease in CD4+ T cell biology remain unknown. Here, using a combination of in vivo and in vitro approaches, we report that granzyme B-deficient CD4+ T cells display increased IL-17 production. In the adoptive transfer model of intestinal inflammation, granzyme B-deficient CD4+ T cells triggered a more rapid disease onset than their WT counterparts, and presented a differential transcription profile. Similar results were also observed in granzyme B-deficient mice infected with Citrobacter rodentium. Our results suggest that granzyme B modulates CD4+ T cell differentiation, providing a new perspective into the biology of this enzyme.

immunology↗

bioRxiv2019

Osteopontin promotes survival of intestinal intraepithelial lymphocytes and protect against colitis

Intestinal intraepithelial lymphocytes (IEL) comprise a diverse population of cells residing in the epithelium at the interface between the intestinal lumen and the sterile environment of the lamina propria. Because of this anatomical location, IEL are considered critical components of intestinal immune responses. Indeed, IEL are involved in many different immunological processes ranging from pathogen control to tissue stability. However, despite their critical importance in mucosal immune responses, very little is known about the homeostasis of different IEL subpopulations. The phosphoprotein osteopontin is important for critical physiological processes, including cellular immune responses such as survival of Th17 cells and homeostasis of NK cells, among others. Because of its impact in the immune system, we investigated the role of osteopontin in the homeostasis of IEL. Here, we report that mice deficient in the expression of osteopontin exhibit reduced numbers of the IEL subpopulations TCR{gamma}{delta}+, TCR{beta}+CD4+, TCR{beta}+CD4+CD8+ and TCR{beta}+CD8+ cells in comparison to wild-type mice. For some IEL subpopulations the decrease in cells numbers could be attributed to apoptosis and reduced cell division. Moreover, we show in vitro that exogenous osteopontin stimulates the survival of murine IEL subpopulations and unfractionated IEL derived from human intestines, an effect mediated by CD44, a known osteopontin receptor. We also show that iCD8 IEL, but not TCR{gamma}{delta}+ IEL, TCR{beta}+ IEL or intestinal epithelial cells, can promote survival of different IEL populations via osteopontin, indicating an important role for iCD8 cells in the homeostasis of IEL. Key PointsO_LIOsteopontin promotes homeostasis of mouse and human IEL, mediated by its ligand CD44 C_LIO_LIiCD8 cells produce osteopontin which impacts the survival of other IEL C_LIO_LILack of osteopontin renders mice susceptible to intestinal inflammation C_LI

immunology↗

bioRxiv2019

Innate CD8aa+ cells and osteopontin promote ILC1-like intraepithelial lymphocyte homeostasis and intestinal inflammation

Innate CD8+ cells, also referred to as iCD8 cells, are TCR-negative intraepithelial lymphocytes (IEL) possessing cytokine and chemokine profiles and functions related to innate immune cells. iCD8 cells constitute an important source of osteopontin in the intestinal epithelium. Osteopontin is a pleiotropic cytokine with diverse roles in bone and tissue remodeling, but also has relevant functions in the homeostasis of immune cells. In this report, we present evidence for the role of iCD8 cells and osteopontin in the homeostasis of TCR-negative NKp46+NK1.1+ IEL (ILC1-like). We show that in the absence of iCD8 cells, the number of NKp46+NK1.1+ IEL is significantly reduced. These ILC1-like cells are involved in intestinal pathogenesis in the anti-CD40 mouse model of intestinal inflammation. Reduced iCD8 cell numbers and/or osteopontin expression results in a milder form of intestinal inflammation in this disease model. Collectively, our results suggest that iCD8 cells and osteopontin promote survival of NKp46+NK1.1+ IEL, which significantly impacts the development of intestinal inflammation.

immunology↗