Jenora T. Waterman

In livestock production settings, repetitive exposure to organic dust (OD) is a risk factor for chronic bronchitis (CB). Macrophages and lymphocytes cooperate to defend the lungs against inhaled dust, but when chronically activated, their actions contribute to chronic inflammation, oxidative stress, and tissue remodeling. Despite the strong body of literature examining the effects of OD exposure on leukocytes and lungs, the contribution of macrophages and lymphocytes to organic dust-associated chronic bronchitis is not fully understood. This review examines the role of macrophages and lymphocytes in organic dust-associated chronic bronchitis. To identify the body of literature addressing this goal, we conducted Boolean searches with keywords (e.g., bronchitis, leukocytes, organic dust) across four major databases: PubMed, Science Direct, Scopus, and Web of Science. From a total of 25,488 hits from all time, 18 research articles (from 2015 to 2025) provided contextual connection for explaining organic dust-associated chronic bronchitis. The results showed continuous or repetitive exposure to OD or its components (e.g., lipopolysaccharide) causes prolonged activation of macrophages and lymphocytes, which leads to overexpression of pro- and anti-inflammatory cytokines and chemokines via Toll-like receptor (TLR)4, TLR2, nuclear factor kappa B, protein kinase C, Extracellular Signal-Regulated Kinase (ERK), and Mitogen-Activated Protein Kinase (MAPK) pathways. Unresolved lung inflammation drives pathologic changes including mucus hypersecretion, airway remodeling, and onset of chronic bronchitis symptoms. Addition of micronutrients or other anti-inflammatory treatment helps to mitigate OD-induced lung inflammation. Defining the cellular and molecular contributions to organic dust-associated chronic bronchitis is essential for the development of targeted therapies that prevent or relieve prolonged airway inflammation.

Magnesium (Mg)-based alloys have the potential for bone repair due to their properties of biodegradation, biocompatibility, and structural stability, which can eliminate the requirement for a second surgery for the removal of the implant. Nevertheless, uncontrolled degradation rate and possible cytotoxicity of the corrosion products at the implant sites are known current challenges for clinical applications. In this study, we assessed in vitro cytotoxicity of different concentrations (0 to 50 mM) of possible corrosion products in the form of magnesium oxide (MgO) and magnesium hydroxide (Mg(OH)₂) nanoparticles (NPs) in human fetal osteoblast (hFOB) 1.19 cells. We measured cell proliferation, adhesion, migration, and cytotoxicity using a real-time, label-free, non-invasive electric cell-substrate impedance sensing (ECIS) system. Our results suggest that 1 mM concentrations of MgO/Mg(OH)₂ NPs are tolerable in hFOB 1.19 cells. Based on our findings, we propose the development of innovative biodegradable Mg-based alloys for further in vivo animal testing and clinical trials in orthopedics.

Repetitive exposure to bioaerosols in swine production facilities (SPF) promotes respiratory dysfunction in workers and animals. An adequate understanding of the impact of the SPF environment on pulmonary physiology is needed. However, there is currently no sufficient ex vivo model to investigate the cause for agriculture-related lung disease. The precision cut lung slices (PCLS) technique represents a practical and useful procedure for ex vivo studies. Our goal was to use the PCLS technique to develop a model of agriculture-related lung diseases using a physi-ologically relevant animal model, the domesticated pig. Freshly prepared pig lung tissue cores were sectioned into 300 mu m slices and viability was measured by lactate dehydrogenase activity and live/dead staining. Airway contrac-tility in response to a methacholine (MCh) dose gradient (10(-7)-10(-4) M) was measured. After the last MCh dose, PCLS were incubated with 1 mM chloroquine to allow airways to relax. Time-lapse images were taken every minute for 35 minutes and used to determine airway lumen area changes. Porcine PCLS remained viable and demonstrated meta-bolic activity for three days. PCLS from indoor and outdoor pigs contracted in response to MCh exposure and relaxed when incubated with chloroquine. Notably, PCLS of indoor pigs showed greater airway constriction in response to 10(-5) M MCh exposure compared to outdoor pig PCLS (P<0.05). These data suggest that exposure to the indoor pig production environment may be associated with hyperresponsiveness in swine airways, and support future studies to investigate lung response to inflammatory substances using the porcine PCLS model.

Biodegradable magnesium (Mg) alloys have potential applications in orthopedic implants due to their mechanical and osseointegration properties. However, the surface characteristics, biocompatibility, and toxicity of the released corrosion products in the form of magnesium oxide (MgO) and magnesium hydroxide (Mg(OH)₂) nanoparticles (NPs) at the junction of implants and in the surrounding tissue are not completely understood. Here, we investigated in vitro cytotoxicity and morphological changes in human fetal osteoblast (hFOB) 1.19 cells in response to various concentrations (1 mM, 5 mM, 10 mM, and 50 mM) of MgO/Mg(OH)₂ NPs by live/dead assay and scanning electron microscopy (SEM). In this study, we performed a surface characterization of MgO/Mg(OH)₂ NPs to evaluate the size of the NPs. Further, an immersion test was performed in Dulbecco’s Modified Eagle’s Medium (DMEM) with randomly selected various concentrations (1 mM, 5 mM, 10 mM, 50 mM, and 100 mM) of MgO/Mg(OH)₂ NPs to understand the degradation behavior of the NPs, and the change in the pH values from days 1 to 7 was measured. After conducting an immersion test for seven days, the highest concentration (100 mM) of MgO/Mg(OH)₂ NPs was selected to study the element depositions on nanoparticles through scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM–EDX) mapping. The results from this in vitro cytotoxicity study suggest that less than or equal to 5-mM concentrations of MgO/Mg(OH)₂ NPs are tolerable concentrations for hFOB 1.19 cells. This study provides a foundational knowledge of MgO/Mg(OH)₂ NP cytotoxicity in hFOB 1.19 cells that can help to develop future sustainable biodegradable magnesium-based alloys for orthopedic applications.

Exposure to indoor swine production facilities (SPF) environments causes airway inflammation and diseases including asthma, chronic bronchitis and chronic obstructive pulmonary disease (COPD) in facility workers. However, less is known about the impact of SPF exposures on the respiratory health of pigs. Respiratory symptoms are associated with repeat exposure to SPF, specifically inhalation of organic dust and other air pollutants therein. A thorough understanding of the molecular pathways regulated by SPF exposure is needed to understand airway inflammation and chronic inflammatory lung disease. The present study measured the expression of proteins associated with oxidative stress and antioxidant defenses in the tracheal epithelial tissues of pigs reared in SPF or on pasture. Proteome profiler cell stress arrays, western blotting and enzyme activity assays were utilized to measure protein expression and activity levels in tracheal epithelial tissue extracts of pigs. It was determined that pigs raised in SPF express significantly less enzymatic antioxidants, including superoxide dismutase (SOD), within their tracheal epithelial tissues compared to pasture raised pigs. Concomitantly, tracheal epithelial tissues of SPF raised pigs had lower SOD and catalase antioxidant activity levels compared to pasture raised pigs. The observations summarized herein provide evidence that exposure to swine production environments influence endogenous enzymatic antioxidant defenses within the tracheal epithelial tissues of pigs. This study offers insight for understanding the effect of continuous exposure to SPF pollutants on endogenous antioxidant defenses in the airway epithelial and may be helpful in understanding human airway responses to swine barn exposures.

Purpose of review Modern food animal production is a major contributor to the global economy, owing to advanced intensive indoor production facilities aimed at increasing market readiness and profit. Consequences of these advances are accumulation of dusts, gases, and microbial products that diminish air quality within production facilities. Chronic inhalation exposure contributes to onset and exacerbation of respiratory symptoms and diseases in animals and workers. This article reviews literature regarding constituents of farm animal production facility dusts, animal responses to production building and organic dust exposure, and the effect of chronic inhalation exposure on pulmonary oxidative stress and inflammation. Recent findings Porcine models of production facility and organic dust exposures reveal striking similarities to observations of human cells, tissues, and clinical data. Oxidative stress plays a key role in mediating respiratory diseases in animals and humans, and enhancement of antioxidant levels through nutritional supplements can improve respiratory health. Summary Pigs are well adapted to the exposures common to swine production buildings and thus serve as excellent models for facility workers. Insight for understanding mechanisms governing organic dust associated respiratory diseases may come from parallel comparisons between farmers and the animals they raise.

The biodegradable ability of magnesium alloys is an attractive feature for tracheal stents since they can be absorbed by the body through gradual degradation after healing of the airway structure, which can reduce the risk of inflammation caused by long-term implantation and prevent the repetitive surgery for removal of existing stent. In this study, the effects of bicarbonate ion (HCO₃⁻) and mucin in Gamble’s solution on the corrosion behavior of AZ31 magnesium alloy were investigated, using immersion and electrochemical tests to systematically identify the biodegradation kinetics of magnesium alloy under in vitro environment, mimicking the epithelial mucus surfaces in a trachea for development of biodegradable airway stents. Analysis of corrosion products after immersion test was performed using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). Electrochemical impedance spectroscopy (EIS) was used to identify the effects of bicarbonate ions and mucin on the corrosion behavior of AZ31 magnesium alloys with the temporal change of corrosion resistance. The results show that the increase of the bicarbonate ions in Gamble’s solution accelerates the dissolution of AZ31 magnesium alloy, while the addition of mucin retards the corrosion. The experimental data in this work is intended to be used as foundational knowledge to predict the corrosion behavior of AZ31 magnesium alloy in the airway environment while providing degradation information for future in vivo studies.