Zinc plays a crucial role in immune regulation, the oxidative stress response, and epithelial barrier integrity, yet zinc's precise role in regulating metabolic and immunological functions in myeloid cells remains poorly understood. Here, we employ a systems biology approach using constraint-based modeling to elucidate the consequences of myeloid-specific loss of ZIP8 on macrophage metabolic function and antibacterial capabilities. We demonstrate that macrophage populations in the lung of ZIP8 knockout (Zip8KO) mice exhibit widespread metabolic disruption, spanning glycolysis, butanoate metabolism, amino acid metabolism, and mitochondrial function. Specifically, Zip8KO macrophages exhibit impaired nutrient uptake and dysregulated energy metabolism, which is exacerbated following Streptococcus pneumoniae infection. Genome-scale metabolic modeling and flux analysis revealed a paradoxical pattern of metabolic suppression prior to infection, followed by overcompensation post-infection, potentially driving immune dysfunction. Consistent with these predictions Zip8KO bone marrow-derived macrophages displayed increased ATP demand and disrupted mitochondrial energetics, compromising their ability to control infection. Importantly, we identified succinate, and kynurenic acid as metabolites capable of restoring immune responses and validated their ability to enhance bacterial clearance in Zip8KO BMDMs. Together, these findings establish ZIP8 as a central regulator of immune-metabolic homeostasis and suggest potential therapeutic avenues to restore immune function in settings of zinc deficiency.

Zinc deficiency impacts billions of people and contributes significantly to the increased incidence of community-acquired pneumonia worldwide. Myeloid cells require the zinc transporter ZIP8 for proper host defense. Previously, we observed that infection with S.pneumoniae in myeloid-specific Zip8 knockout mice (Zip8KO) results in increased bacterial burden and mortality despite increased recruitment of macrophages into the lung. Here, we reveal that the lungs of infected Zip8KO mice generate a unique population of dysfunctional macrophages with defects in phagolysosomal function and cell survival. In particular, Zip8KO bone marrow-derived macrophages have increased bacterial accumulation due to deficits in lysosomal number and function via defective mTORC1/TFEB signaling. Knowing that labile Zn cannot enter the cytosol through ZIP8 and that ZIP8 loss impairs butanoate synthesis by the gut microbiome, both previously reported by our group, we reveal an alternative treatment strategy via extended oral phenylbutyrate supplementation. Despite ongoing ZIP8-mediated impairment of lung host defense, phenylbutyrate restored macrophage-mediated bacterial clearance and improved host outcomes. Given the high incidence of diet-induced Zn deficiency and the rs13107325 ZIP8 defective variant allele in humans, future investigations that foster preventive, patient-centered treatment strategies that counter immune dysfunction due to Zn dyshomeostasis are warranted. ZIP8 loss decreases intracellular zinc uptake in macrophages in response to bacterial pneumonia and impairs phagolysosomal function and bacterial clearance. Despite ongoing zinc dyshomeostasis, prolonged butyrate supplementation corrects bacterial clearance and improves survival.

Alcohol misuse is a known risk factor for pneumonia, and up to 50% of individuals who misuse alcohol are zinc deficient. Chronic alcohol misuse can lead to alcohol-induced ciliary dysfunction (AICD), preventing effective mucociliary clearance and protection against lung infection. Because zinc salts fail to alter AICD, we hypothesized a form of zinc (Zinpro Zinc LG) with enhanced cell uptake would protect against AICD. Human and mouse airway epithelial cells were treated with 50 mM ethanol for 1-24 h followed by the ciliostimulatory agents. Cilia beat frequency (CBF) and cAMP-dependent protein kinase (PKA) activity were assayed. Cyclic AMP or beta agonists stimulated a significant increase in CBF, but 24 h alcohol pretreatment resulted in the desensitization of the cilia to these agents. Pretreatment of cells with 1-10 µg/mL Zinpro Zinc LG prior to alcohol restored the cAMP cilia stimulation response. Zinpro Zinc LG alone produced no effects and was not toxic at <10 µg/mL. PKA activation was prevented in cells treated with alcohol for 24 h, but pretreatment with Zinpro Zinc LG prior to alcohol restored kinase activation. Zinpro Zinc LG prevented alcohol-stimulation of Protein Phosphatase-1, the regulator of PKA desensitization. These data demonstrate that the exposomal combination of alcohol and nutritional Zn deficiency could lead to an aberrant ciliary clearance response that may be prevented by effective zinc supplementation.

PURPOSE:Alcohol misuse is widely accepted as an independent risk factor for a wide variety of lung diseases, such as pneumonia and acute respiratory distress syndrome. Alcohol induces changes in the regulatory mechanisms of the lung, both at a mechanical and immunological level. Understanding these changes might help discover new targets for drugs and therapeutic approaches for the prevention of respiratory disease following alcohol misuse. SEARCH METHODS:A systematic literature search was conducted on January 25, 2025, in PubMed, Medline, and Embase of manuscripts published between January 2000 and January 2025 using the terms ("alcohol" or "ethanol") AND ("lung," or "respiratory," or "pulmonary") AND ("pneumonia" or "damage" or "leak"). Eligible manuscripts included studies that discussed the effects of ethanol on the lungs. SEARCH RESULTS:A total of 962 publications were identified; after excluding duplicates and research not covering alcohol-related lung effects (e.g., studies investigating liver damage or alcohol-related tissue injury; 814 articles), 148 studies were reviewed. An additional 15 papers from before 2000 were included as historical precedents for the current research cited. Of the 148 studies, 114 were cited in this review; previous review articles and those discussing in utero or prenatal alcohol exposure were excluded (34 articles). DISCUSSION AND CONCLUSIONS:The lungs are particularly susceptible to infections and injury following alcohol misuse. Several key mechanisms by which alcohol misuse drives lung damage have been identified. Alcohol misuse leads to impaired mucus-facilitated clearance of bacterial pathogens, increases the aspiration of microbes from the upper alimentary tract, and suppresses tissue recruitment and function of innate and adaptive immune cells. Alcohol-related reductions in antioxidant levels, trace metals, and metabolites may also contribute to lung disease in people with underlying alcohol misuse. Several regulatory molecules may play crucial roles in alcohol-induced disease processes. Although there are currently no approved therapies to combat the detrimental effects of chronic alcohol consumption on the respiratory system, these molecules may be potential therapeutic targets to guide future investigation. Despite these advancements, limitations and knowledge gaps in the field still exist. For example, few studies have investigated dose- and duration-dependent effects of alcohol on the lung, sex-specific differences in lung responses, and the interaction of alcohol with other coexposures/comorbidities, such as smoking and HIV. In addition, well-defined observational and longitudinal human studies employing robust measures of alcohol use are limited. These gaps represent novel opportunities for more thorough and robust experimental designs of human and animal studies investigating alcohol-associated lung disease.

Heavy alcohol drinking is known to increase the risk of bacterial pneumonia. However, the link between alcohol levels and risk of infection remains underexplored. Recently, we found that alcohol induced α2‐6sialo mucin O‐glycans in human tracheobronchial epithelial cells, which mediated the killing of U937 macrophages. By extending this study, we focus here on whether altered glycans induced by alcohol in human airway epithelial cells can promote adhesion of Klebsiella pneumoniae (Kp) and Streptococcus pneumoniae (Sp). We have found that exposure of human tracheal epithelial cells to alcohol also induces high mannose N‐glycans terminated with α3mannose and increases adhesion of Kp, which is inhibited by αmethylmannoside or aldehyde dehydrogenase 2 activator 1. Further, the α2‐6sialo mucin O‐glycans induced by alcohol in human tracheal epithelial cells also enhance the adhesion of Sp, which is inhibited by ovine submaxillary mucin or aldehyde dehydrogenase 2 activator 1. We conclude that alcohol induces altered glycans in human airway epithelial cells, which increase the risk of bacterial pneumonia by compromising immune function and promoting the adhesion of Kp and Sp.

RATIONALE: Alcohol misuse in rural populations is now a recognized public health problem. Alcohol has a negative impact on innate defense, including decreased bacterial clearance from the lung, leading to increased community-acquired pneumonia. Previously, we have demonstrated lung epithelial cilia slowing, delayed wound repair, and proinflammatory cytokine release in response to organic dust exposure due to activation of protein kinase C epsilon (PKC). In addition, we have identified the uncoupling of the cilia stimulatory cyclic AMP-dependent protein kinase (PKA) in response to lung alcohol exposure. We hypothesized that the combination of dust and alcohol treatment in S. pneumoniae-infected mice would result in increased lung burden and decreased clearance beyond that of dust or alcohol alone.METHODS: Wild-type C57BL/6 mice received water or alcohol ad libitum for a total of 8 weeks. Mice received nasal instillations with 50 µL of either sterile saline or 12% organic dust extract (ODE) collected from swine barns for a 2-week period (N=5 mice/group). Mice were then nasally instilled with sterile saline or 1x105 CFU of S. pneumoniae, sacrificed after 48 hr, and tissues collected for lung bacterial burden, barrier function, lavage cells and cytokines, PKC activity, tracheal cilia beat frequency (CBF), and histopathology.RESULTS: Co-exposure of mice with ODE and alcohol increased lung bacterial burden significantly (5 x 102 vs. 1.0 x 103 log CFU; p<0.05) compared to either dust or alcohol alone as shown by colony forming unit assay and PCR. Tracheal PKC was increased two-fold and CBF was decreased by 2 Hz in the co-exposure group compared to dust or alcohol alone. Lung histopathology revealed the highest inflammatory score in the dust and alcohol co-exposure group. Proinflammatory cytokines (TNF alpha, CXCL1), increased in the dust+alcohol co-exposed mice, were not increased in the alcohol-only mice, and were similar to dust-only mice. CONCLUSION: Together, these studies provide evidence that alcohol misuse in the setting of agricultural dust inhalation exposure can decrease innate mechanical clearance of bacteria and place such workers at enhanced risk for community-acquired pneumonia.

Agricultural workers exposed to organic dust from swine concentrated animal feeding operations (CAFOs) have increased chances of contracting chronic lung disease. Mucociliary clearance represents a first line of defense against inhaled dusts, but organic dust extracts (ODEs) from swine barns cause cilia slowing, leading to decreased bacterial clearance and increased lung inflammation. Because nutritional zinc deficiency is associated with chronic lung disease, we examined the role of zinc supplementation in ODE-mediated cilia slowing. Ciliated mouse tracheal epithelial cells were pretreated with 0–10 µg/mL ZinProTM for 1 h, followed by treatment with 5% ODE for 24 h. Cilia beat frequency (CBF) and protein kinase C epsilon (PKCε) activity were assayed. ODE treatment resulted in cilia slowing after 24 h, which was reversed with 0.5 and 1.0 µg/mL ZinPro pre-treatment. No zinc protection was observed at 50 ng/mL, and ciliated cells detached at high concentrations (100 µg/mL). ZinPro alone produced no changes in the baseline CBF and showed no toxicity to the cells at concentrations of up to 10 µg/mL. Pre-treatment with ZinPro inhibited ODE-stimulated PKCε activation in a dose-dependent manner. Based on ZinPro’s superior cell permeability compared to zinc salts, it may be therapeutically more effective at reversing ODE-mediated cilia slowing through a PKCε pathway. These data demonstrate that zinc supplementation may support the mucociliary transport apparatus in the protection of CAFO workers against dust-mediated chronic lung disease.

Chronic Obstructive Pulmonary Disease (COPD) affects 30 million Americans. Previous epidemiologic work has shown that diet can impact pulmonary function in those with and without COPD. Diet is also a major driver of gut microbiome composition and function. Importantly, the gut microbiome has also been associated with lung health (i.e., the gut-lung axis) in both preclinical and clinical studies. Despite this growing body of evidence, many questions remain regarding the gut-lung axis. Specifically, how the microbiome impacts the relationship between diet factors and spirometry or stage of disease in people with COPD is little understood. We hypothesize that there are taxonomic differences in the gut microbiome among the different stages of COPD and that diet microbiome interactions influence pulmonary function. This study aimed to identify how the GI microbiota correlated with the severity of respiratory disease in COPD patients and how the microbiome may mediate the relationship between diet, including fiber and omega-3 fatty acids, and lung function outcomes.

Alcohol misuse increases infections and cancer fatalities, but mechanisms underlying its toxicity are ill‐defined. We show that alcohol treatment of human tracheobronchial epithelial cells leads to inactivation of giantin‐mediated Golgi targeting of glycosylation enzymes. Loss of core 2 N‐acetylglucosaminyltransferase 1, which uses only giantin for Golgi targeting, coupled with shifted targeting of other glycosylation enzymes to Golgi matrix protein 130‐Golgi reassembly stacking protein 65, the site normally used by core 1 enzyme, results in loss of sialyl Lewis x and increase of sialyl Lewis a and α2‐6sialo mucin O‐glycans. The α2‐6sialo mucin O‐glycans induced by alcohol cause death of U937 macrophages mediated by sialic acid‐binding immunoglobulin‐like lectin 7. These results provide a mechanistic insight into the cause of the toxic effects of alcohol and might contribute to the development of therapies to alleviate its toxicity.

Alcohol use is an independent risk factor for the development of bacterial pneumonia due, in part, to impaired mucus-facilitated clearance, macrophage phagocytosis, and recruitment of neutrophils. Alcohol consumption is also known to reduce peripheral natural killer (NK) cell numbers and compromise NK cell cytolytic activity, especially NK cells with a mature phenotype. However, the role of innate lymphocytes, such as NK cells during host defense against alcohol-associated bacterial pneumonia is essentially unknown. We have previously shown that indole supplementation mitigates increases in pulmonary bacterial burden and improves pulmonary NK cell recruitment in alcohol-fed mice, which were dependent on aryl hydrocarbon receptor (AhR) signaling. Employing a binge-on-chronic alcohol-feeding model we sought to define the role and interaction of indole and NK cells during pulmonary host defense against alcohol-associated pneumonia. We demonstrate that alcohol dysregulates NK cell effector function and pulmonary recruitment via alterations in two key signaling pathways. We found that alcohol increases transforming growth factor beta (TGF-β) signaling while suppressing AhR signaling. We further demonstrated that NK cells isolated from alcohol-fed mice have a reduced ability to kill Klebsiella pneumoniae. NK cell migratory capacity to chemokines was also significantly altered by alcohol, as NK cells isolated from alcohol-fed mice exhibited preferential migration in response to CXCR3 chemokines but exhibited reduced migration in response to CCR2, CXCR4, and CX3CR1 chemokines. Together this data suggests that alcohol disrupts NK cell-specific TGF-β and AhR signaling pathways leading to decreased pulmonary recruitment and cytolytic activity thereby increasing susceptibility to alcohol-associated bacterial pneumonia.

The human commensal microbiota is now widely accepted as a key regulator of human health and disease. The composition of the mucosal associated microbiota has been shown to play a critical role in the lung health. The role of the mucosal microbiota in the development and severity of allergy, asthma, and occupational lung disease is only beginning to take shape. However, advances in our understanding of these links have tremendous potential to led to new clinical interventions to reduce allergy, asthma, and occupational lung disease morbidity. We review recent work describing the relationship and role of the commensal microbiota in the development of allergy, asthma, and occupational lung disease. Our review primarily focuses on occupational exposures and the effects of the microbiome, both in composition and function. Data generated from these studies may lead to the development of interventions targeted at establishing and maintaining a healthy microbiota. We also highlight the role of environmental exposures and the effects on the commensal microbial community and their potential association with occupational lung disease. This review explores the current research describing the role of the human microbiome in the regulation of pulmonary health and disease, with a specific focus on the role of the mucosal microbiota in the development of allergy, asthma, and occupational lung disease.

Dietary long-chain omega-3 polyunsaturated fatty acids (n-3 PUFA) and their pro-resolving metabolites are protective against atherosclerotic disease, and ameliorate systemic inflammatory conditions including lupus erythematosus, psoriasis, and bronchial asthma. Organic bioaerosol inhalation is a common and injurious hazard associated with agricultural occupations such as work in swine concentrated animal feeding operations (CAFOs) and is known to increase the risk for developing respiratory conditions such as asthma and COPD. Nearly all cells secrete membrane-bound vesicles (extracellular vesicles, EVs) that have the capacity to transmit protein, nucleic acid, and lipid signaling mediators between cells. Using a polymer-based isolation technique (ExoQuick, PEG) followed by ultracentrifugation, EVs were isolated from CAFO dust extracts, and were quantified and partially characterized. Here, we investigated the role of the n-3 PUFA docosahexaenoic acid (DHA) as a component of n-6 to n-3 PUFA mixtures used to recapitulate physiologically relevant dietary ratios in the resolution of inflammatory injury caused by exposure to EVs carried by agricultural organic dust in vitro. Primary human bronchial epithelial cells, fibroblasts and monocyte-derived macrophages were exposed to EVs isolated from swine CAFO dust. Cells were treated with mixtures of n-6 and n-3 PUFA during recovery from the EV-induced injury. CAFO dust extract (DE) was found to contain EVs that contributed significantly to the overall consequences of exposure to complete DE. DHA-rich PUFA ratios inhibited DE-derived EV-induced proinflammatory cytokine release dose-dependently. DHA-rich PUFA ratios also reversed the damaging effects of EVs on recellularization of lung matrix scaffolds, accelerated wound healing, and stimulated the release of pro-resolution mediators. These results underscore the importance of n-3 PUFA as anti-inflammatory compounds during recovery from EV-laden environmental dust exposure in the context of cellular responses in vitro, warranting future translational studies.

Alcohol use is an independent risk factor for the development of bacterial pneumonia due, in part, to impaired mucus-facilitated clearance, macrophage phagocytosis, and recruitment of neutrophils. Alcohol consumption is also known to reduce peripheral natural killer (NK) cell numbers and compromises NK cell cytolytic activity, especially NK cells with a mature phenotype. However, the role of innate lymphocytes, such as NK cells during host defense against alcohol-associated bacterial pneumonia is essentially unknown. We have previously shown that indole supplementation mitigates increases in pulmonary bacterial burden and improves pulmonary NK cell recruitment in alcohol-fed mice, which were dependent of aryl hydrocarbon receptor (AhR) signaling. Employing a binge-on-chronic alcohol-feeding model we sought to define the role and interaction of indole and NK cells during pulmonary host defense against alcohol-associated pneumonia. We demonstrate that alcohol dysregulates NK cell effector function and pulmonary recruitment via alterations in two key signaling pathways. We found that alcohol increases transforming growth factor beta (TGF-β) signaling, while suppressing AhR signaling. We further demonstrated that NK cells isolated from alcohol-fed mice have a reduced ability to kill Klebsiella pneumoniae. NK cell migratory capacity to chemokines was also significantly altered by alcohol, as NK cells isolated from alcohol-fed mice exhibited preferential migration in response to CXCR3 chemokines but exhibited reduced migration in response to CCR2, CXCR4, and CX3CR1 chemokines. Together this data suggests that alcohol disrupts NK cell specific TGF-β and AhR signaling pathways leading to decreased pulmonary recruitment and cytolytic activity thereby increasing susceptibility to alcohol-associated bacterial pneumonia.

Preclinical studies have shown that chronic alcohol abuse leads to alterations in the gastrointestinal microbiota that are associated with behavior changes, physiological alterations, and immunological effects. However, such studies have been limited in their ability to evaluate the direct effects of alcohol-associated dysbiosis. To address this, we developed a humanized alcohol-microbiota mouse model to systematically evaluate the immunological effects of chronic alcohol abuse mediated by intestinal dysbiosis. Germ-free mice were colonized with human fecal microbiota from individuals with high and low Alcohol Use Disorders Identification Test (AUDIT) scores and bred to produce human alcohol-associated microbiota or human control-microbiota F1 progenies. F1 offspring colonized with fecal microbiota from individuals with high AUDIT scores had increased susceptibility to Klebsiella pneumoniae and Streptococcus pneumoniae pneumonia, as determined by increased mortality rates, pulmonary bacterial burden, and post-infection lung damage. These findings highlight the importance of considering both the direct effects of alcohol and alcohol-induced dysbiosis when investigating the mechanisms behind alcohol-related disorders and treatment strategies.

Intestinal dysbiosis increases susceptibility to infection through the alteration of metabolic profiles, which increases morbidity. Zinc (Zn) homeostasis in mammals is tightly regulated by 24 Zn transporters. ZIP8 is unique in that it is required by myeloid cells to maintain proper host defense against bacterial pneumonia. In addition, a frequently occurring ZIP8 defective variant (SLC39A8 rs13107325) is strongly associated with inflammation-based disorders and bacterial infection. In this study, we developed a novel model to study the effects of ZIP8-mediated intestinal dysbiosis on pulmonary host defense independent of the genetic effects. Cecal microbial communities from a myeloid-specific Zip8 knockout mouse model were transplanted into germ-free mice. Conventionalized ZIP8KO-microbiota mice were then bred to produce F1 and F2 generations of ZIP8KO-microbiota mice. F1 ZIP8KO-microbiota mice were also infected with S. pneumoniae, and pulmonary host defense was assessed. Strikingly, the instillation of pneumococcus into the lung of F1 ZIP8KO-microbiota mice resulted in a significant increase in weight loss, inflammation, and mortality when compared to F1 wild-type (WT)-microbiota recipients. Similar defects in pulmonary host defense were observed in both genders, although consistently greater in females. From these results, we conclude that myeloid Zn homeostasis is not only critical for myeloid function but also plays a significant role in the maintenance and control of gut microbiota composition. Further, these data demonstrate that the intestinal microbiota, independent of host genetics, play a critical role in governing host defense in the lung against infection. Finally, these data strongly support future microbiome-based interventional studies, given the high incidence of zinc deficiency and the rs13107325 allele in humans.