Biology subjects

Piazuelo, M. B.

Publications and source records attributed to Piazuelo, M. B..

8 recordsLinked to original sources

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

Endogenous glucocorticoids moderate the gastric inflammatory response to Helicobacter infection and protect from autoimmunity.

Background and AimsImmune responses to infection must balance pathogen clearance with minimizing tissue damage and autoimmunity. Chronic gastric inflammation caused by H. pylori damages the gastric mucosa and promotes carcinogenesis. Glucocorticoids are immunoregulatory hormones that limit immune activation in the stomach. This study aimed to determine how endogenous glucocorticoids regulate the gastric immune response to Helicobacter infection and their impact on preneoplastic lesion development. MethodsWe examined the role of endogenous glucocorticoids in shaping the gastric immune response to Helicobacter felis colonization. Gastric immune cell infiltration, atrophy, metaplasia, and preneoplastic lesion development were evaluated in adrenal-intact control mice and adrenalectomized (ADX) mice. Auto-reactive IgG antibodies were assessed using a mouse self-antigen array and by measuring their binding to healthy gastric tissue. ResultsLoss of endogenous glucocorticoids led to significantly increased H. felis-induced gastric T cell infiltration and proinflammatory cytokine expression compared to intact-infected controls. While all intact mice maintained chronic infection for up to 12 months, nearly all ADX mice eradicated H. felis within 2-3 weeks. Despite bacterial clearance, ADX mice continued to exhibit chronic gastric inflammation and developed dysplasia. Autoantibody profiling showed that both intact and ADX groups generated self-reactive IgG during active infection. However, only ADX mice sustained autoantibody production following bacterial eradication. ConclusionsEndogenous glucocorticoids attenuate gastric inflammation during Helicobacter infection, supporting bacterial persistence while maintaining immune tolerance. These findings suggest that heightened immune responses to H. pylori may trigger autoimmune gastritis (AIG) development, which can persist after H. pylori clearance and continue to drive gastric cancer risk.

immunology↗

bioRxiv2024

Chronic cigarette smoke exposure masks pathological features of Helicobacter pylori infection while promoting tumor initiation

Gastric cancer is the fifth most common cancer and the fifth leading cause of cancer deaths worldwide. Chronic infection by the bacterium Helicobacter pylori is the most prominent gastric cancer risk factor, but only 1-3% of infected individuals will develop gastric cancer. Cigarette smoking is another independent gastric cancer risk factor, and H. pylori-infected smokers are at a 2-11-fold increased risk of gastric cancer development, but the direct impacts of cigarette smoke on H. pylori pathogenesis remain unknown. In this study, male C57BL/6 mice were infected with H. pylori and began smoking within one week of infection. The mice were exposed to cigarette smoke (CS) five days/week for 8 weeks. CS exposure had no notable impact on gross gastric morphology or inflammatory status compared to filtered-air (FA) exposed controls in mock-infected mice. However, CS exposure significantly blunted H. pylori-induced gastric inflammatory responses, reducing gastric atrophy and pyloric metaplasia development. Despite blunting these classic pathological features of H. pylori infection, CS exposures increased DNA damage within the gastric epithelial cells and accelerated H. pylori-induced dysplasia onset in the INS-GAS gastric cancer model. These data suggest that cigarette smoking may clinically silence classic clinical symptoms of H. pylori infection but enhance the accumulation of mutations and accelerate gastric cancer initiation.

cancer biology↗

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↗

bioRxiv2021

MTG16 (CBFA2T3) represses E protein-dependent transcription to regulate colonic secretory cell differentiation, epithelial regeneration, and tumorigenesis

Aberrant epithelial differentiation and regeneration contribute to colon pathologies including inflammatory bowel disease (IBD) and colitis-associated cancer (CAC). MTG16 (CBFA2T3) is a transcriptional corepressor expressed in the colonic epithelium. MTG16 deficiency in mice exacerbates colitis and increases tumor burden in CAC, though the underlying mechanisms remain unclear. Here, we identified MTG16 as a central mediator of epithelial differentiation, promoting goblet and restraining enteroendocrine cell development in homeostasis and enabling regeneration following dextran sulfate sodium (DSS)-induced colitis. Transcriptomic analyses implicated increased E box-binding transcription factor (E protein) activity in MTG16-deficient colon crypts. Using a novel mouse model with a point mutation that disrupts MTG16:E protein complex formation (Mtg16P209T), we established that MTG16 exerts control over colonic epithelial differentiation and regeneration by repressing E protein-mediated transcription. Mimicking murine colitis, MTG16 expression was increased in biopsies from patients with active IBD compared to unaffected controls. Finally, uncoupling MTG16:E protein interactions only partially phenocopied the enhanced tumorigenicity of Mtg16-/- colon in the azoxymethane(AOM)/DSS-induced model of CAC, indicating that MTG16 protects from tumorigenesis through additional mechanisms. Collectively, our results demonstrate that MTG16, via its repression of E protein targets, is a key regulator of cell fate decisions during colon homeostasis, colitis, and cancer. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/467178v3_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@21948borg.highwire.dtl.DTLVardef@9f60eeorg.highwire.dtl.DTLVardef@194b9fdorg.highwire.dtl.DTLVardef@13eb1a7_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

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↗