Biology subjects

Jaramillo, A. M.

Publications and source records attributed to Jaramillo, A. M..

9 recordsLinked to original sources

bioRxiv2025

Airway Secretory Cells Contain Both a Perinuclear Golgi Ribbon and Dispersed Golgi Satellites

RationaleFinely tuned production and secretion of the polymeric mucins MUC5AC and MUCB are required for lung health, but knowledge of many details between their translation and their packaging into secretory granules is lacking. ObjectivesTo analyze the structure and function of the Golgi apparatus, a key site of mucin glycosylation, folding, polymerization and packaging, in airway epithelial secretory cells. MethodsLung tissue was obtained from mice stimulated or not with IL-13 to upregulate mucin production, and from normal human lungs. Golgi elements in mouse and human tissue were imaged by high-resolution immunofluorescence microscopy and electron microscopy. Tissue from mice with deletion of both polymeric mucins was also examined. Measurements and Main ResultsBy immunofluorescence microscopy, both mouse and human airway secretory cells contained [~]100 dispersed puncta labeled by markers of medial and trans Golgi cisternae and the trans-Golgi network (TGN), but only a few perinuclear puncta were labeled by markers of cis-Golgi cisternae. By electron microscopy, secretory cells contained both a perinuclear Golgi ribbon and numerous dispersed Golgi stacks, termed satellites. In mucous metaplastic cells, satellites were concentrated among immature mucin granules. Increasing mucin production by cytokine stimulation did not increase the number of TGN puncta, nor did preventing polymeric mucin production by gene deletion reduce TGN puncta. ConclusionsMucin-producing airway secretory cells express an unusual Golgi structure consisting of a conventional perinuclear Golgi ribbon as well as dispersed satellites. While the Golgi satellites are likely an adaptation for mucin production and packaging, their presence is specified developmentally, independent of mucin production.

cell biology↗

bioRxiv2024

Siglec-F Deficiency Prevents Fibrosis After Bleomycin-Induced Acute Lung Injury

Injury to the lungs causes acute inflammation that can lead to pathological lung fibrosis. Airspace macrophages (AMs) are critical for repair of injured tissue, but they can contribute fibrosis through mechanisms that are incompletely understood. Siglecs are expressed by immune cells. In mice, Siglec-F is chiefly expressed AMs where it is considered inflammosuppressive. We hypothesized that its deletion would worsen lung injury and fibrosis in response to intratracheal bleomycin challenge. We evaluated Siglec-F expression and function in mice challenged with bleomycin on days 7, 14, and 21 post-challenge (2.5 U/kg). AMs were the predominant inflammatory cells at all timepoints, and they included resident (RAM) and recruited (RecAM) subsets. Siglec-F deficiency prevented fibrosis than in Siglecf-/- mouse lungs, as evident from biochemical and histologic readouts. We performed RNAseq on pooled RAMs and RecAMs from wild type and Siglec-F deficient mice. Lung fibrosis 21 d after bleomycin challenge was associated with differentially expressed genes (DEGs) related to cholesterol synthesis and metabolism. In AMs from healthy lung lavage fluid and idiopathic pulmonary fibrosis patient tissues, the human paralogs Siglec-7 and Siglec-9 were expressed. Findings here identify novel mechanisms that control protective and detrimental functions of AMs after lung injury.

physiology↗

bioRxiv2024

Requirement for Fucosyltransferase 2 in Allergic Airway Hyperreactivity and Mucus Obstruction

Mucus hypersecretion is an important pathological problem in respiratory diseases. Mucus accumulates in the airways of people with asthma, and it contributes to airflow limitation by forming plugs that occlude airways. Current treatments have minimal effects on mucus or its chief components, the polymeric mucin glycoproteins MUC5AC and MUC5B. This treatment gap reflects a poor molecular understanding of mucins that could be used to determine how they contribute to airway obstruction. Due to the prominence of glycosylation as a defining characteristic of mucins, we investigated characteristics of mucin glycans in asthma and in a mouse model of allergic asthma. Mucin fucosylation was observed in asthma, and in healthy mice it was induced as part of a mucous metaplastic response to allergic inflammation. In allergically inflamed mouse airways, mucin fucosylation was dependent on the enzyme fucosyltransferase 2 (Fut2). Fut2 gene deficient mice were protected from asthma-like airway hyperreactivity and mucus plugging. These findings provide mechanistic and translational links between observations in human asthma and a mouse model that may help improve therapeutic targeting of airway mucus.

physiology↗

bioRxiv2022

The Colon Mucosal Sialylglycome Is Redox-Regulated by the Golgi Enzyme QSOX1

Mucus shields the intestinal epithelium from pathogens and provides a supportive environment for commensal bacteria. Mucus is composed of enormous, heavily glycosylated proteins called mucins, which become disulfide crosslinked in a multi-step biosynthetic pathway culminating in the Golgi apparatus and secretory granules of goblet cells. We observed that knockout mice lacking the Golgi-localized disulfide catalyst QSOX1 produced poorly protective colon mucus, were hypersensitive to induced colitis, and had an altered microbiome. The initial hypothesis arising from these observations was that QSOX1 catalyzes disulfide crosslinking of mucins. Contrary to this hypothesis, the disulfide-mediated polymerization of mucins and related glycoproteins proceeded normally without QSOX1. Instead, we found that QSOX1 forms regulatory disulfides in Golgi glycosyltransferases and thereby promotes effective sialylation of the colon glycome. Our findings reveal that enzymatic control of Golgi redox state impacts glycan elaboration in goblet cells, and that this pathway is crucial for maintaining mucosal function.

cell biology↗

bioRxiv2021

Epithelial Immunomodulation by Aerosolized Toll-like Receptor Agonists Attenuates Allergic Responsiveness in Mice

Allergic asthma is a chronic inflammatory respiratory disease associated with eosinophilic infiltration, increased mucus production, airway hyperresponsiveness (AHR), and airway remodeling. Epidemiologic data has revealed that the prevalence of allergic sensitization and associated diseases has increased in the twentieth century. This has been hypothesized to be partly due to reduced contact with microbial organisms (the hygiene hypothesis) in industrialized society. Airway epithelial cells, once considered a static physical barrier between the body and the external world, are now widely recognized as immunologically active cells that can initiate, maintain, and restrain inflammatory responses, such as those that mediate allergic disease. Airway epithelial cells can sense allergens via myriad expression of Toll-like receptors (TLRs) and other pattern-recognition receptors (PRRs). We sought to determine whether the innate immune response stimulated by a combination of Pam2CSK4 ("Pam2", TLR2/6 ligand) and a class C oligodeoxynucleotide ODN362 ("ODN", TLR9 ligand) when delivered together by aerosol ("Pam2ODN"), can modulate the allergic immune response to allergens. Treatment with Pam2ODN 7 days before sensitization to House Dust Mite (HDM) extract resulted in a strong reduction in eosinophilic and lymphocytic inflammation. This Pam2ODN immunomodulatory effect was also seen using Ovalbumin (OVA) and A. oryzae (Ao) mouse models. The immunomodulatory effect was observed as much as 30 days before sensitization to HDM, but ineffective just 2 days after sensitization, suggesting that Pam2ODN immunomodulation lowers the allergic responsiveness of airway epithelial cells. Furthermore, Pam2 and ODN cooperated synergistically suggesting that this treatment is superior to any single agonist in the setting of allergen immunotherapy. One Sentence SummaryA synergistic combination of Toll-like Receptor agonists, delivered directly into the lung mucosa, can attenuate allergic responsiveness of airway epithelial cells and prevent host sensitization to aeroallergens. What is already knownO_LIAllergic sensitization has increased in the 20th century due to reduced contact with microbial organisms in industrialized society (ie. hygiene hypothesis) C_LIO_LIWe have previously identified a pharmacological means to stimulate innate immunity of lung epithelial cells. C_LI What this study addsO_LIActivation of innate immunity in lung epithelial cells attenuates the allergic responsiveness of mice. C_LIO_LISynergistic cooperation of pattern recognition receptors induces stronger immunomodulatory responses C_LI What is the clinical significanceO_LIAerosolized Toll-like Receptor agonists have been demonstrated as safe in human clinical trials C_LIO_LIThis study provides proof-of-principle that aerosolized toll-like receptor agonists could have clinical efficacy in the setting of the allergen immunotherapy C_LI

immunology↗

bioRxiv2020

Immune modulation to improve survival of respiratory virus infections in mice

Viral pneumonia remains a global health threat requiring novel treatment strategies, as strikingly exemplified in the SARS-CoV-2 pandemic of 2019-2020. We have reported that mice treated with a combination of inhaled Toll-like receptor (TLR) 2/6 and TLR 9 agonists (Pam2-ODN) to stimulate innate immunity are broadly protected against respiratory pathogens, but the mechanisms underlying this protection remain incompletely elucidated. Here, we show in a lethal paramyxovirus model that Pam2-ODN-enhanced survival is associated with robust virus inactivation by reactive oxygen species (ROS), which occurs prior to internalization by lung epithelial cells. However, we also found that mortality in sham-treated mice temporally corresponded with CD8+ T cell-enriched lung inflammation that peaks on days 11-12 after viral challenge, when the viral burden has waned to a scarcely detectable level. Pam2-ODN treatment blocked this injurious inflammation by reducing the viral burden, and alternatively, depleting CD8+ T cells 8 days after viral challenge also decreased mortality. These findings reveal opportunities for targeted immunomodulation to protect susceptible individuals against the morbidity and mortality of respiratory viral infections.

immunology↗

bioRxiv2020

Inducible epithelial resistance improves survival of Sendai virus pneumonia in mice by both inactivating virus and preventing CD8+ T cell-mediated immunopathology

Viral pneumonias remain a global health threat necessitating novel strategies to prevent and treat these lower respiratory tract infections. We have reported that mice treated with a combination of inhaled Toll-like receptor (TLR) 2/6 and TLR 9 agonists (Pam2-ODN) are broadly protected against respiratory pathogens. Although a single inhalation of Pam-ODN prevents acute morbidity and chronic complications associated with viral pneumonias, the mechanisms underlying this protection remain incompletely elucidated. Here, we show in a lethal paramyxovirus model that Pam2-ODN-enhanced survival is associated with robust virus inactivation that occurs prior to internalization by lung epithelial cells. However, it was also noted that viral mortality in sham-treated mice temporally corresponded with CD8+ T cell-enriched lung inflammation that peaks after the viral burden wanes. Pam2-ODN treatment also blocked this injurious inflammation, but the attenuation of lymphocytic inflammation and the reduction in virus burden were both lost when inducible reactive oxygen species generation was inhibited. Depleting CD8+ T cells before or after viral challenge underscored the balanced roles of CD8+ T cells in antiviral immunity and fatal immunopathology, but did not obviate the Pam2-ODN antiviral protection. These findings identify multifunctional inducible antiviral mechanisms and may reveal means to protect susceptible individuals against respiratory infections.

immunology↗

bioRxiv2019

Aerosolized TLR Agonists Suppress Acute Sendai Virus Lung Infection and Chronic Airway Disease in Mice

Respiratory viral infections play central roles in the initiation, exacerbation and progression of asthma in humans. An acute paramyxoviral infection in mice can cause a chronic lung disease that resembles human asthma. We sought to determine whether reduction of Sendai virus lung burden in mice by stimulating innate immunity with aerosolized Toll-like receptor (TLR) agonists could attenuate the severity of chronic asthma-like lung disease. Treatment with 1 {micro}M oligodeoxynucleotide (ODN) M362, an agonist of the TLR9 homodimer, and 4 {micro}M Pam2CSK4 (Pam2), an agonist of the TLR2/6 heterodimer, within a few days before or after Sendai virus challenge, resulted in a [~]75% reduction in lung Sendai virus burden five days after challenge. The reduction in acute lung virus burden was associated with marked reductions 49 days after viral challenge in eosinophilic and lymphocytic lung inflammation, airway mucous metaplasia, lumenal mucus occlusion, and hyperresponsiveness to methacholine. Mechanistically, ODN/Pam2 treatment attenuated the chronic asthma phenotype by suppressing IL-33 production by type 2 pneumocytes, both by reducing the severity of acute infection and by downregulating Type 2 (allergic) inflammation. These data suggest that treatment of susceptible human hosts with aerosolized ODN and Pam2 at the time of a respiratory viral infection might attenuate the severity of the acute infection and reduce progression of asthma.\n\nOne Sentence SummaryRespiratory viral infections can induce chronic airway disease, and we find that stimulating innate immunity within the lungs of mice reduces the severity of acute infection and development of a chronic asthma phenotype.

immunology↗

bioRxiv2018

Different Munc18 Proteins Mediate Baseline and Stimulated Airway Mucin Secretion

Airway mucin secretion is necessary for ciliary clearance of inhaled particles and pathogens, but can be detrimental in pathologies such as asthma and cystic fibrosis. Exocytosis in mammals requires a Munc18 scaffolding protein, and airway secretory cells express all three Munc18 isoforms. Using conditional airway epithelial deletant mice, we found that Munc18a has the major role in baseline mucin secretion, Munc18b has the major role in stimulated mucin secretion, and Munc18c does not function in mucin secretion. In an allergic asthma model, Munc18b deletion reduced airway mucus occlusion and airflow resistance. In a cystic fibrosis model, Munc18b deletion reduced airway mucus occlusion and emphysema. Munc18b deficiency in the airway epithelium did not result in any abnormalities of lung structure, particle clearance, inflammation, or bacterial infection. Our results show that regulated secretion in a polarized epithelial cell may involve more than one exocytic machine at the apical plasma membrane, and that the protective roles of mucin secretion can be preserved while therapeutically targeting its pathologic roles.

cell biology↗