Publications by authors named "Jay C Horvat"

Background And Objective: Severe asthma is a heterogeneous disease with subtype classification according to dominant airway infiltrates, including eosinophilic (Type 2 high), or non-eosinophilic asthma. Non-eosinophilic asthma is further divided into paucigranulocytic or neutrophilic asthma characterized by elevated neutrophils, and mixed Type 1 and Type 17 cytokines in the airways. Severe non-eosinophilic asthma has few effective treatments and many patients do not qualify for biologic therapies.

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There is increasing evidence that thirdhand exposure to e-cigarette vapor (e-vapor) can have detrimental effects on the lungs. However, whether maternal exposure during pregnancy results in harmful changes to the offspring is unknown. Using two different e-cigarette settings (low vs.

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Influenza A virus (IAV) infection is a major health risk during pregnancy. Although vaccination and antiviral agents are widely used and reduce IAV-induced symptoms, they are not sufficient to control IAV infections in pregnancy, especially during pandemics. Respiratory viruses like IAV exploit immune alterations that occur during pregnancy, including the upregulation of immune checkpoint proteins (ICPs) like programmed death ligand-1 (PDL1), programmed cell death receptor 1 (PD1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA4).

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Respiratory infections are one of the most common causes of illness and morbidity in neonates worldwide. In the acute phase infections are known to cause wide-spread peripheral inflammation. However, the inflammatory consequences to the critical neural control centres for respiration have not been explored.

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Background: Millions of people are exposed to landscape fire smoke (LFS) globally, and inhalation of LFS particulate matter (PM) is associated with poor respiratory and cardiovascular outcomes. However, how LFS affects respiratory and cardiovascular function is less well understood.

Objective: We aimed to characterize the pathophysiologic effects of representative LFS airway exposure on respiratory and cardiac function and on asthma outcomes.

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Thymic stromal lymphopoietin (TSLP) is an epithelial-derived pleiotropic cytokine that regulates T-helper 2 (Th2) immune responses in the lung and plays a major role in severe uncontrolled asthma. Emerging evidence suggests a role for endoplasmic reticulum (ER) stress in the pathogenesis of asthma. In this study, we determined if ER stress and the unfolded protein response (UPR) signaling are involved in TSLP induction in the airway epithelium.

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Early life inflammation has been linked to long-term modulation of behavioural outcomes due to the central nervous system, but it is now becoming apparent it is also linked to dysfunction of visceral physiology. The medulla oblongata contains a number of nuclei critical for homeostasis, therefore we utilised the well-established model of neonatal lipopolysaccharide (LPS) exposure to examine the immediate and long-term impacts of systemic inflammation on the medulla oblongata. Wistar rats were injected with LPS or saline on postnatal days 3 and 5, with tissues collected on postnatal days 7 or 90 in order to assess expression of inflammatory mediators and microglial morphology in autonomic regions of the medulla oblongata.

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Article Synopsis
  • - The uterus maintains a balance in immune responses, allowing for fetal development while offering protection against infections, particularly focusing on the role of natural killer (NK) cells during infection.
  • - Researchers discovered that IFNε, a type of immune factor present in the uterus, is essential for enhancing NK cell accumulation and activation during Chlamydia infections.
  • - IFNε works by boosting IL-15 production from local immune cells and directly supporting the growth and activation of NK cell progenitors, highlighting its unique role in defending against uterine infections.
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Article Synopsis
  • * The study involved analyzing immune cells from asthma patients (both non-severe and severe) and healthy individuals to assess how they respond to certain stimuli and whether an NLRP3 inhibitor (MCC950) could suppress IL-1β release.
  • * Results indicate that both severe and non-severe asthma patients have heightened IL-1β responses, suggesting inflammasome activation is a shared characteristic and that targeting its inhibition could be a viable treatment option across various asthma forms.
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Toll-like receptor 7 (TLR7) is known for eliciting immunity against single-stranded RNA viruses, and is increased in both human and cigarette smoke (CS)-induced, experimental chronic obstructive pulmonary disease (COPD). Here we show that the severity of CS-induced emphysema and COPD is reduced in TLR7-deficient mice, while inhalation of imiquimod, a TLR7-agonist, induces emphysema without CS exposure. This imiquimod-induced emphysema is reduced in mice deficient in mast cell protease-6, or when wild-type mice are treated with the mast cell stabilizer, cromolyn.

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Article Synopsis
  • The study investigates whether the pneumococcal polysaccharide vaccine (PPV) can reduce atherosclerosis in humans, similar to findings in mouse models through molecular mimicry.
  • A national trial, AUSPICE, is underway to track cardiovascular disease (CVD) events and includes a substudy measuring various biomarkers over four years.
  • Results show increased anti-pneumococcal antibodies in the vaccinated group, but no improvement in CVD surrogate markers or metabolic indicators, with final findings on actual CVD events pending next year.
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Introduction: An association between functional dyspepsia (FD) and wheat-containing foods has been reported in observational studies; however, an adaptive response has not been demonstrated. We examined whether antigens present in wheat could provoke a response from FD duodenal lymphocytes.

Methods: Lamina propria mononuclear cells (LPMCs) were isolated from duodenal biopsies from 50 patients with FD and 23 controls.

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Influenza A virus (IAV) infections are increased during pregnancy especially with asthma as a comorbidity, leading to asthma exacerbations, secondary bacterial infections, intensive care unit admissions, and mortality. We aimed to define the processes involved in increased susceptibility and severity of IAV infections during pregnancy, especially with asthma. We sensitized mice to house dust mite (HDM), induced pregnancy, and challenged with HDM to induce allergic airway disease (AAD).

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Background: Individuals with asthma experienced severe and prolonged symptoms after the Australian 2019 to 2020 landscape fire. Many of these symptoms, such as throat irritation, occur in the upper airway. This suggests that laryngeal hypersensitivity contributes to persistent symptoms after smoke exposure.

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Background: Obesity is associated with more severe asthma, however, the mechanisms responsible are poorly understood. Obesity is also associated with low-grade systemic inflammation; it is possible that this inflammation extends to the airways of adults with asthma, contributing to worse asthma outcomes. Accordingly, the aim of this review was to examine whether obesity is associated with increased airway and systemic inflammation and adipokines, in adults with asthma.

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Background: The 2019/2020 Australian landscape fires (bushfires) resulted in prolonged extreme air pollution; little is known about the effects on breastfeeding women and their infants. This study aimed to examine the impact of prolonged landscape fires on infant feeding methods and assess the concentration of polycyclic aromatic hydrocarbons (PAHs) and elements in breast milk samples.

Methods: From May - December 2020, women with asthma, who were feeding their infants during the fires, were recruited from an existing cohort.

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Lung transcriptomics studies in asthma have provided valuable information in the whole lung context, however, deciphering the individual contributions of the airway and parenchyma in disease pathogenesis may expedite the development of novel targeted treatment strategies. In this study, we performed transcriptomics on the airway and parenchyma using a house dust mite (HDM)-induced model of experimental asthma that replicates key features of the human disease. HDM exposure increased the expression of 3,255 genes, of which 212 were uniquely increased in the airways, 856 uniquely increased in the parenchyma, and 2187 commonly increased in both compartments.

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Background: Functional dyspepsia is characterised by chronic symptoms of post-prandial distress or epigastric pain not associated with defined structural pathology. Increased peripheral gut-homing T cells have been previously identified in patients. To date, it is unknown if these T cells were antigen-experienced, or if a specific phenotype was associated with FD.

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are prominent gut commensals that produce the short-chain fatty acid (SCFA) acetate, and they are often used as probiotics. Connections between the gut and the lung, termed the gut-lung axis, are regulated by the microbiome. The gut-lung axis is increasingly implicated in cigarette smoke-induced diseases, and cigarette smoke exposure has been associated with depletion of species.

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Background: Little is known about the physical and mental health impact of exposure to landscape fire smoke in women with asthma. This study examined the health impacts and information-seeking behaviours of women with asthma exposed to the 2019/2020 Australian fires, including women who were pregnant.

Methods: Women with asthma were recruited from the Breathing for Life Trial in Australia.

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Article Synopsis
  • Tissue-resident natural killer (trNK) cells in the lungs may play a significant role in respiratory immunity, especially in chronic lung diseases like COPD, but their exact functions are not well understood.
  • Researchers conducted a study on mice exposed to cigarette smoke to mimic COPD and analyzed trNK cell behaviors in both mouse and human lung tissues when infected with influenza A virus.
  • Findings revealed that specific NK cell populations, especially CD49a NK cells, exhibited altered functions during COPD, showing increased activity when confronted with viral infections, which could lead to heightened inflammation in COPD patients.
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Workers in the mining and construction industries are at increased risk of respiratory and other diseases as a result of being exposed to harmful levels of airborne particulate matter (PM) for extended periods of time. While clear links have been established between PM exposure and the development of occupational lung disease, the mechanisms are still poorly understood. A greater understanding of how exposures to different levels and types of PM encountered in mining and construction workplaces affect pathophysiological processes in the airways and lungs and result in different forms of occupational lung disease is urgently required.

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Wildfires are increasing and cause health effects. The immediate and ongoing health impacts of prolonged wildfire smoke exposure in severe asthma are unknown. This longitudinal study examined the experiences and health impacts of prolonged wildfire (bushfire) smoke exposure in adults with severe asthma during the 2019/2020 Australian bushfire period.

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Immune mediators upregulated in peripheral to central immune communication can modulate respiratory function by direct action on brainstem respiratory circuits. In this systematic review we consolidated findings from independent studies examining the relationship between peripheral and neuro- inflammation within brainstem respiratory centres. Microglia and astrocytes modulate brainstem neuroinflammation in response to peripheral immune mediators which then regulates neuronal activity and ultimately respiratory behaviours.

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