Respiratory exposure to agricultural dust extract promotes increased intestinal Tnfα expression, gut barrier dysfunction, and endotoxemia in mice.

Concentrated animal feeding operations (CAFOs) are responsible for the production of global greenhouse gases and harmful environmental pollutants including hydrogen sulfide, ammonia, and particulate matter. Swine farmers are frequently exposed to organic dust that is proinflammatory in the lung and are thus at greater risk of developing pneumonia, asthma, and other respiratory conditions. In addition to respiratory disease, air pollutants are directly associated with altered gastrointestinal (GI) physiology and the development of GI diseases, thereby highlighting the gut-lung axis in disease progression. Instillation of hog dust extract (HDE) for 3 wk has been reported to promote the development of chronic airway inflammation in mice, however, the impact of HDE exposure on intestinal homeostasis is poorly understood. We report that 3-wk intranasal exposure of HDE is associated with increased intestinal macromolecule permeability and elevated serum endotoxin concentrations in C57BL/6J mice. In vivo studies also indicated mislocalization of the epithelial cell adhesion protein, E-cadherin, in the colon as well as an increase in the proinflammatory cytokine, Tnfα, in the proximal colon. Moreover, mRNA expression of the Paneth cell-associated marker, Lyz1, was increased the proximal colon, whereas the expression of the goblet cell marker, Muc2, was unchanged in the epithelial cells of the ileum, cecum, and distal colon. These results demonstrate that airway exposure to CAFOs dusts promote airway inflammation and modify the gastrointestinal tract to increase intestinal permeability, induce systemic endotoxemia, and promote intestinal inflammation. Therefore, this study identifies complex physiological consequences of chronic exposure to organic dusts derived from CAFOs on the gut-lung axis.NEW & NOTEWORTHY Agricultural workers have a higher prevalence of occupational respiratory symptoms and are at greater risk of developing respiratory diseases. However, gastrointestinal complications have also been reported, yet the intestinal pathophysiology is understudied. This work is novel because it emphasizes the role of an inhaled environmental pollutant on the development of intestinal pathophysiological outcomes. This work will provide foundation for other studies evaluating how agricultural dusts disrupts host physiology and promotes debilitating gastrointestinal and systemic disorders.

PTPN2 regulates bacterial clearance in a mouse model of enteropathogenic and enterohemorrhagic E. coli infection.

Macrophages intimately interact with intestinal epithelial cells, but the consequences of defective macrophage-epithelial cell interactions for protection against enteric pathogens are poorly understood. Here, we show that in mice with a deletion in protein tyrosine phosphatase nonreceptor type 2 (PTPN2) in macrophages, infection with Citrobacter rodentium, a model of enteropathogenic and enterohemorrhagic E. coli infection in humans, promoted a strong type 1/IL-22-driven immune response, culminating in accelerated disease but also faster clearance of the pathogen. In contrast, deletion of PTPN2 specifically in epithelial cells rendered the epithelium unable to upregulate antimicrobial peptides and consequently resulted in a failure to eliminate the infection. The ability of PTPN2-deficient macrophages to induce faster recovery from C. rodentium was dependent on macrophage-intrinsic IL-22 production, which was highly increased in macrophages deficient in PTPN2. Our findings demonstrate the importance of macrophage-mediated factors, and especially macrophage-derived IL-22, for the induction of protective immune responses in the intestinal epithelium, and show that normal PTPN2 expression in the epithelium is crucial to allow for protection against enterohemorrhagic E. coli and other intestinal pathogens.

Lipopolysaccharide and the gut microbiota: considering structural variation.

Systemic inflammation is associated with chronic disease and is purported to be a main pathogenic mechanism underlying metabolic conditions. Microbes harbored in the host gastrointestinal tract release signaling byproducts from their cell wall, such as lipopolysaccharides (LPS), which can act locally and, after crossing the gut barrier and entering circulation, also systemically. Defined as metabolic endotoxemia, elevated concentrations of LPS in circulation are associated with metabolic conditions and chronic disease. As such, measurement of LPS is highly prevalent in animal and human research investigating these states. Indeed, LPS can be a potent stimulant of host immunity, but this response depends on the microbial species' origin, a parameter often overlooked in both preclinical and clinical investigations. Indeed, the lipid A portion of LPS is mutable and comprises the main virulence and endotoxic component, thus contributing to the structural and functional diversity among LPSs from microbial species. In this review, we discuss how such structural differences in LPS can induce differential immunological responses in the host.

Loss of protein tyrosine phosphatase non-receptor type 2 reduces IL-4-driven alternative macrophage activation.

Macrophages are a heterogeneous population of innate immune cells that are often divided into two major subsets: classically activated, typically pro-inflammatory (M1) macrophages that mediate host defense, and alternatively activated, tolerance-inducing (M2) macrophages that exert homeostatic and tissue-regenerative functions. Disturbed macrophage function/differentiation results either in inadequate, excessive immune activation or in a failure to induce efficient protective immune responses against pathogens. Loss-of-function variants in protein tyrosine phosphatase non-receptor type 2 (PTPN2) are associated with chronic inflammatory disorders, but the effect of macrophage-intrinsic PTPN2 loss is still poorly understood. Here we report that PTPN2-deficient macrophages fail to acquire an alternatively activated/M2 phenotype. This was the consequence of reduced IL-6 receptor expression and a failure to induce IL-4 receptor in response to IL-6, resulting in an inability to respond to the key M2-inducing cytokine IL-4. Ultimately, failure to adequately respond to IL-6 and IL-4 resulted in increased levels of M1 macrophage marker expression in vitro and exacerbated lung inflammation upon infection with Nippostrongylus brasiliensis in vivo. These results demonstrate that PTPN2 loss interferes with the ability of macrophages to adequately respond to inflammatory stimuli and might explain the increased susceptibility of PTPN2 loss-of-function carriers to developing inflammatory diseases.

Induction of distinct neuroinflammatory markers and gut dysbiosis by differential pyridostigmine bromide dosing in a chronic mouse model of GWI showing persistent exercise fatigue and cognitive impairment.

AIMS: To characterize neuroinflammatory and gut dysbiosis signatures that accompany exaggerated exercise fatigue and cognitive/mood deficits in a mouse model of Gulf War Illness (GWI). METHODS: Adult male C57Bl/6N mice were exposed for 28 d (5 d/wk) to pyridostigmine bromide (P.O.) at 6.5 mg/kg/d, b.i.d. (GW1) or 8.7 mg/kg/d, q.d. (GW2); topical permethrin (1.3 mg/kg), topical N,N-diethyl-meta-toluamide (33%) and restraint stress (5 min). Animals were phenotypically evaluated as described in an accompanying article [124] and sacrificed at 6.6 months post-treatment (PT) to allow measurement of brain neuroinflammation/neuropathic pain gene expression, hippocampal glial fibrillary acidic protein, brain Interleukin-6, gut dysbiosis and serum endotoxin. KEY FINDINGS: Compared to GW1, GW2 showed a more intense neuroinflammatory transcriptional signature relative to sham stress controls. Interleukin-6 was elevated in GW2 and astrogliosis in hippocampal CA1 was seen in both GW groups. Beta-diversity PCoA using weighted Unifrac revealed that gut microbial communities changed after exposure to GW2 at PT188. Both GW1 and GW2 displayed systemic endotoxemia, suggesting a gut-brain mechanism underlies the neuropathological signatures. Using germ-free mice, probiotic supplementation with Lactobacillus reuteri produced less gut permeability than microbiota transplantation using GW2 feces. SIGNIFICANCE: Our findings demonstrate that GW agents dose-dependently induce differential neuropathology and gut dysbiosis associated with cognitive, exercise fatigue and mood GWI phenotypes. Establishment of a comprehensive animal model that recapitulates multiple GWI symptom domains and neuroinflammation has significant implications for uncovering pathophysiology, improving diagnosis and treatment for GWI.

JAK-STAT Pathway Regulation of Intestinal Permeability: Pathogenic Roles and Therapeutic Opportunities in Inflammatory Bowel Disease.

The epithelial barrier forms the interface between luminal microbes and the host immune system and is the first site of exposure to many of the environmental factors that trigger disease activity in chronic inflammatory bowel disease (IBD). Disruption of the epithelial barrier, in the form of increased intestinal permeability, is a feature of IBD and other inflammatory diseases, including celiac disease and type 1 diabetes. Variants in genes that regulate or belong to the JAK-STAT signaling pathway are associated with IBD risk. Inhibitors of the JAK-STAT pathway are now effective therapeutic options in IBD. This review will discuss emerging evidence that JAK inhibitors can be used to improve defects in intestinal permeability and how this plays a key role in resolving intestinal inflammation.

Every breath you take: Impacts of environmental dust exposure on intestinal barrier function-from the gut-lung axis to COVID-19.

As countries continue to industrialize, major cities experience diminished air quality, whereas rural populations also experience poor air quality from sources such as agricultural operations. These exposures to environmental pollution from both rural and populated/industrialized sources have adverse effects on human health. Although respiratory diseases (e.g., asthma and chronic obstructive pulmonary disease) are the most commonly reported following long-term exposure to particulate matter and hazardous chemicals, gastrointestinal complications have also been associated with the increased risk of lung disease from inhalation of polluted air. The interconnectedness of these organ systems has offered valuable insights into the roles of the immune system and the micro/mycobiota as mediators of communication between the lung and the gut during disease states. A topical example of this relationship is provided by reports of multiple gastrointestinal symptoms in patients with coronavirus disease 2019 (COVID-19), whereas the rapid transmission and increased risk of COVID-19 has been linked to poor air quality and high levels of particulate matter. In this review, we focus on the mechanistic effects of environmental pollution on disease progression with special emphasis on the gut-lung axis.

Probiotic Supplementation Has a Limited Effect on Circulating Immune and Inflammatory Markers in Healthy Adults: A Systematic Review of Randomized Controlled Trials.

BACKGROUND: A main mechanism of action proposed for oral probiotic supplementation is immunomodulation, which is expected to impart health benefits in the host by influencing circulating immune and inflammatory factors. To date, the effectiveness of probiotic supplementation for immunomodulation in healthy adults without disease has not been evaluated in a systematic review. OBJECTIVE: The objective of this systematic review was to evaluate the effect of probiotic supplementation on circulating immune and inflammatory markers of healthy adults compared to placebo. METHODS: PubMed, SCOPUS, ISI Web of Science, ProQuest, and Cochrane databases were searched for English articles up to May 15, 2019. Additional papers were identified by checking references of relevant papers. Only randomized controlled trials studying the administration of probiotic supplements compared to placebo on immune and inflammatory markers in healthy adults (aged 18 to 65 years), without acute or chronic disease, and in generally good health were examined. Independent extraction of articles was conducted by two authors using predefined search terms and restrictions/filters. The methodologic quality of each study was appraised using the Academy of Nutrition and Dietetics Evidence Analysis Library Quality Rating Worksheet and the body of evidence was assessed using the Academy of Nutrition and Dietetics Grade Definitions and Conclusion Grading Table. RESULTS: Eighteen articles, including 819 subjects, met eligibility criteria and were included in the present systematic review. Five articles were rated neutral in quality and 13 were rated high in quality. Eight articles reported a significant effect on immune and/or inflammatory parameters including increases in natural killer cells, lymphocytes, and monocytes, and decreases in proinflammatory cytokine concentrations. CONCLUSIONS: Based on the 18 articles extracted in this systemic review, probiotic supplementation was concluded to have a limited effect on immune and inflammatory markers in healthy adults. Overall, the evidence was heterogenous, precluding a meta-analysis, and difficult to aggregate and conclude on effect size. SYSTEMATIC REVIEW REGISTRATION NUMBER: PROSPERO ref CRD42018110856.

A comparison of the nutritional physiology and gut microbiome of urban and rural house sparrows (Passer domesticus).

Urbanization influences food quality and availability for many wild species, but our knowledge of the consequences urbanization has on the nutritional physiology of these animals is currently limited. To fill this gap, we captured House Sparrows (Passer domesticus) from rural and urban environments and hypothesized that increased access to human refuse in urban areas may significantly alter the gut microbiome and nutritional physiology of Sparrows. While there were no significant differences in circulating triglycerides or free glycerol concentrations between populations, urban birds had significantly greater blood glucose concentrations, which suggests greater circulating glucagon concentrations, accessibility to carbohydrates, and/or higher rates of gluconeogenesis in an urban setting. Rural birds had significantly more plasma uric acid, suggesting that they may metabolize more proteins or experience lower inflammation than urban birds. Rural birds also had significantly higher liver free glycerol concentrations, indicating that they metabolize more fat than urban birds. There were no significant differences in the relative abundance of gut microbial taxa at the phyla level between the two populations, but linear discriminant analysis effect size (LEfSe) showed that urban House Sparrows were more enriched with class- and order-level microbes from the phylum Proteobacteria, which are implicated in several mammalian intestinal and extra-intestinal diseases. These findings demonstrate that urbanization significantly alters the nutritional physiology and the composition of the gut microbiome of House Sparrows.

A novel organic mineral complex prevented high fat diet-induced hyperglycemia, endotoxemia, liver injury and endothelial dysfunction in young male Sprague-Dawley rats.

The prevalence of metabolic syndrome (MetSyn) has risen 35% since 2012 and over two-thirds of Americans exhibit features characterizing this condition (obesity, dyslipidemia, hyperglycemia, insulin resistance and/or endothelial dysfunction). The aim of this study was to evaluate the effects of a novel dietary supplemental organic mineral complex (OMC) on these risk factors in a rodent model of MetSyn. Six-week old male Sprague-Dawley rats were fed either standard chow or a high-fat diet (HFD) composed of 60% kcal from fat for 10 weeks. Rats were also treated with OMC in their drinking water at either 0 mg/mL (control), 0.6 mg/mL, or 3.0 mg/mL. The HFD-treated rats exhibited significantly increased body mass (p<0.05), epididymal fat pad mass (p<0.001), waist circumference (p = 0.010), in addition to elevations in plasma endotoxins (p<0.001), ALT activity (p<0.001), fasting serum glucose (p = 0.025) and insulin concentrations (p = 0.009). OMC did not affect body weight or adiposity induced by the HFD. At the higher dose OMC significantly blunted HFD-induced hyperglycemia (p = 0.021), whereas both low and high doses of OMC prevented HFD-induced endotoxemia (p = 0.002 and <0.001, respectively) and hepatocyte injury (ALT activity, p<0.01). Despite evidence of oxidative stress (elevated urinary H2O2 p = 0.032) in HFD-fed rats, OMC exhibited no demonstrable antioxidative effect. Consistent with prior studies, mesenteric arteries from HFD rats had more uncoupled eNOS (p = 0.006) and iNOS protein expression (p = 0.027) in addition to impaired endothelium-dependent vasodilation that was abrogated by the high dose of OMC (p<0.05). This effect of OMC may be attributed to the high nitrate content of the supplement. These findings suggest that the OMC supplement, particularly at the higher dose, ameliorated several risk factors associated with MetSyn via a non-antioxidant-dependent mechanism.

Six-Week High-Fat Diet Alters the Gut Microbiome and Promotes Cecal Inflammation, Endotoxin Production, and Simple Steatosis without Obesity in Male Rats.

Energy-dense foods can alter gut microbial diversity. However, the physiological effects of diet-induced microbial changes on the development of nonalcoholic fatty liver disease (NAFLD) remain debatable. We hypothesized that high-fat intake for 6 weeks would promote intestinal dysbiosis by increasing gram-positive bacteria, inducing the intestinal production of proinflammatory cytokines and subsequent hepatic lipid infiltration in young male rats. Six-week old male Sprague-Dawley rats were divided into two groups and fed either a standard rodent chow or a 60% high-fat diet (HFD) for 6 weeks. Chromogenic endotoxin quantification assays indicate an increase in lipopolysaccharide concentration in the plasma of HFD rats (p = 0.032). Additionally, Western blot analyses of the cecum showed significantly greater protein expression of the transcription factor, nuclear factor kappa B (NF-kB), (p = 0.037) and the proinflammatory cytokine, interleukin-1ß (IL-1ß), (p = 0.042) in rats fed HFD. Linear discriminate analysis of effect size (LEfSe) showed greater abundance of Firmicutes and Actinobacteria in the samples collected from the cecum of HFD rats compared to chow. Consistent with the development of steatosis, the Oil-Red-O-stained area was increased in liver sections from HFD rats. Hepatic triacylglycerol concentrations (p < 0.001) and plasma alanine aminotransferase (p < 0.001) were significantly increased in HFD-fed animals compared to chow. These findings show that a short duration of high-fat consumption can have profound deleterious effects on gastrointestinal health and the inflammatory state of these young male Sprague-Dawley rats.

Self-reference and emotional memory effects in older adults at increased genetic risk of Alzheimer's disease.

The present study investigated whether cognitively healthy older adults who are carriers of the ε4 allele of apolipoprotein E, the most prevalent genetic risk factor for late-onset Alzheimer's disease, benefit from self-referential processing and emotional processing to the same degree as noncarriers of this gene. Participants encoded emotional and nonemotional narratives using a baseline-orienting task, semantic elaboration, or imagination-based self-referential processing and then completed a recognition memory test. Both groups of older adults showed enhanced recognition memory for narrative information following self-referential processing relative to semantic elaboration, and the magnitude of this memory effect was not affected by ε4 status. However, older adult ε4 carriers did not show an emotional enhancement effect, whereas older adult ε4 noncarriers did. These results indicate that whereas the self-reference effect is not attenuated in cognitively healthy older adults ε4 carriers, deficits in emotional memory may be an early cognitive marker of abnormal decline.