Effects of cigarette smoke condensate on the production and characterization of exopolysaccharides by Bifidobacterium

A synbiotic mixture of Bifidobacterium breve M16-V, oligosaccharides and pectin, enhances Short Chain Fatty Acid production and improves lung health in a preclinical model for pulmonary neutrophilia

Introduction

Pulmonary neutrophilia is a hallmark of numerous airway diseases including Chronic Obstructive Pulmonary Disease (COPD), Neutrophilic asthma, Acute Lung Injury (ALI), Acute Respiratory Distress Syndrome (ARDS) and COVID-19. The aim of the current study was to investigate the effect of dietary interventions on lung health in context of pulmonary neutrophilia.

Methods

Male BALB/cByJ mice received 7 intra-nasal doses of either a vehicle or lipopolysaccharides (LPS). To study the effect of nutritional interventions they received 16 intra-gastric doses of either a vehicle (PBS) or the following supplements (1) probiotic Bifidobacterium breve (B. breve) M16-V; (2) a prebiotic fiber mixture of short-chain galacto-oligosaccharides, long-chain fructo-oligosaccharides, and low-viscosity pectin in a 9:1:2 ratio (scGOS/lcFOS/lvPectin); and (3) A synbiotic combination B. breve M16-V and scGOS/lcFOS/lvPectin. Parameters for lung health included lung function, lung morphology and lung inflammation. Parameters for systemic immunomodulation included levels of fecal short chain fatty acids and regulatory T cells.

Results

The synbiotic supplement protected against the LPS induced decline in lung function (35% improved lung resistance at baseline p = 0.0002 and 25% at peak challenge, p = 0.0002), provided a significant relief from pulmonary neutrophilia (40.7% less neutrophils, p < 0.01) and improved the pulmonary neutrophil-to-lymphocyte ratio (NLR) by 55.3% (p = 0.0033). Supplements did not impact lung morphology in this specific experiment. LPS applied to the upper airways induced less fecal SCFAs production compared to mice that received PBS. The production of acetic acid between day -5 and day 16 was increased in all unchallenged mice (PBS-PBS p = 0.0003; PBS-Pro p < 0.0001; PBS-Pre, p = 0.0045; PBS-Syn, p = 0.0005) which upon LPS challenge was only observed in mice that received the synbiotic mixture of B. breve M16-V and GOS:FOS:lvPectin (p = 0.0003). A moderate correlation was found for butyric acid and lung function parameters and a weak correlation was found between acetic acid, butyric acid and propionic acid concentrations and NLR.

Conclusion

This study suggests bidirectional gut lung cross-talk in a mouse model for pulmonary neutrophilia. Neutrophilic lung inflammation coexisted with attenuated levels of fecal SCFA. The beneficial effects of the synbiotic mixture of B. breve M16-V and GOS:FOS:lvPectin on lung health associated with enhanced levels of SCFAs.

Tumorigenesis in Inflammatory Bowel Disease: Microbiota-Environment Interconnections

Colo-rectal cancer (CRC) is undoubtedly one of the most severe complications of inflammatory bowel diseases (IBD). While sporadic CRC develops from a typical adenoma-carcinoma sequence, IBD-related CRC follows different and less understood pathways and its pathophysiological mechanisms were not completely elucidated. In contrast to chronic inflammation, which is nowadays a well-recognised drive towards neoplastic transformation in IBD, only recently was gut microbiota demonstrated to interfere with both inflammation processes and immune-mediated anticancer surveillance. Moreover, the role of microbiota appears particularly complex and intriguing when also considering its multifaceted interactions with multiple environmental stimuli, notably chronic pathologies such as diabetes and obesity, lifestyle (diet, smoking) and vitamin intake. In this review, we presented a comprehensive overview on current evidence of the influence of gut microbiota on IBD-related CRC, in particular its mutual interconnections with the environment.

Cross-talks between gut microbiota and tobacco smoking: a two-sample Mendelian randomization study

BACKGROUND

Considerable evidence has been reported that tobacco use could cause alterations in gut microbiota composition. The microbiota-gut-brain axis also in turn hinted at a possible contribution of the gut microbiota to smoking. However, population-level studies with a higher evidence level for causality are lacking.

METHODS

This study utilized the summary-level data of respective genome-wide association study (GWAS) for 211 gut microbial taxa and five smoking phenotypes to reveal the causal association between the gut microbiota and tobacco smoking. Two-sample bidirectional Mendelian randomization (MR) design was deployed and comprehensively sensitive analyses were followed to validate the robustness of results. We further performed multivariable MR to evaluate the effect of neurotransmitter-associated metabolites on observed associations.

RESULTS

Our univariable MR results confirmed the effects of smoking on three taxa (Intestinimonas, Catenibacterium, and Ruminococcaceae, observed from previous studies) with boosted evidence level and identified another 13 taxa which may be causally affected by tobacco smoking. As for the other direction, we revealed that smoking behaviors could be potential consequence of specific taxa abundance. Combining with existing observational evidence, we provided novel insights regarding a positive feedback loop of smoking through Actinobacteria and indicated a potential mechanism for the link between parental smoking and early smoking initiation of their children driven by Bifidobacterium. The multivariable MR results suggested that neurotransmitter-associated metabolites (tryptophan and tyrosine, also supported by previous studies) probably played a role in the action pathway from the gut microbiota to smoking, especially for Actinobacteria and Peptococcus.

CONCLUSIONS

In summary, the current study suggested the role of the specific gut microbes on the risk for cigarette smoking (likely involving alterations in metabolites) and in turn smoking on specific gut microbes. Our findings highlighted the hazards of tobacco use for gut flora dysbiosis and shed light on the potential role of specific gut microbiota for smoking behaviors.

Probiotic Bifidobacterium longum subsp. longum Protects against Cigarette Smoke-Induced Inflammation in Mice

Bifidobacterium 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 Bifidobacterium species. In this study, we assessed the impact of acetate-producing Bifidobacterium longum subsp. longum (WT) and a mutant strain with an impaired acetate production capacity (MUT) on cigarette smoke-induced inflammation. The mice were treated with WT or MUT B. longum subsp. longum and exposed to cigarette smoke for 8 weeks before assessments of lung inflammation, lung tissue gene expression and cecal SCFAs were performed. Both strains of B. longum subsp. longum reduced lung inflammation, inflammatory cytokine expression and adhesion factor expression and alleviated cigarette smoke-induced depletion in caecum butyrate. Thus, the probiotic administration of B. longum subsp. longum, irrespective of its acetate-producing capacity, alleviated cigarette smoke-induced inflammation and the depletion of cecal butyrate levels.

Crosstalk Between Lung and Extrapulmonary Organs in Infection and Inflammation

Acute and chronic lung inflammation is a risk factor for various diseases involving lungs and extrapulmonary organs. Intercellular and interorgan networks, including crosstalk between lung and brain, intestine, heart, liver, and kidney, coordinate host immunity against infection, protect tissue, and maintain homeostasis. However, this interaction may be counterproductive and cause acute or chronic comorbidities due to dysregulated inflammation in the lung. In this chapter, we review the relationship of the lung with other key organs during normal cell processes and disease development. We focus on how pneumonia may lead to a systemic pathophysiological response to acute lung injury and chronic lung disease through organ interactions, which can facilitate the development of undesirable and even deleterious extrapulmonary sequelae.

Effects of Cigarette Smoke Condensate on Growth and Biofilm Formation by Mycobacterium tuberculosis

MATERIALS AND METHODS

The planktonic and biofilm-forming cultures were prepared in Middlebrook 7H9 and Sauton broth media, respectively, using Mtb strain, H37Rv. The effects of CSC at concentrations of 0.05-3.12 mg/L on growth, biofilm formation and structure were evaluated using microplate Alamar Blue assay, spectrophotometric procedure and scanning electron microscopy (SEM), respectively. Involvement of reactive oxygen species in CSC-mediated biofilm formation was investigated by including catalase in biofilm-forming cultures.

RESULTS

CSC did not affect the growth of planktonic bacteria, but rather led to a statistically significant increase in biofilm formation at concentrations of 0.4-3.12 mg/L, as well as in the viability of biofilm-forming bacteria at CSC concentrations of 0.2-1.56 mg/L. SEM confirmed an agglomerated biofilm matrix and irregular bacterial morphology in CSC-treated biofilms. Inclusion of catalase caused significant attenuation of CSC-mediated augmentation of biofilm formation by Mtb, implying involvement of oxidative stress. These findings demonstrate that exposure of Mtb to CSC resulted in increased biofilm formation that appeared to be mediated, at least in part, by oxidative stress, while no effect on planktonic cultures was observed.

CONCLUSION

Smoking-related augmentation of biofilm formation by Mtb may contribute to persistence of the pathogen, predisposing to disease reactivation and counteracting the efficacy of antimicrobial chemotherapy.

Smoking and microbiome in oral, airway, gut and some systemic diseases

The human microbiome harbors a diverse array of microbes which establishes a mutually beneficial relation with the host in healthy conditions, however, the dynamic homeostasis is influenced by both host and environmental factors. Smoking contributes to modifications of the oral, lung and gut microbiome, leading to various diseases, such as periodontitis, asthma, chronic obstructive pulmonary disease, Crohn’s disease, ulcerative colitis and cancers. However, the exact causal relationship between smoking and microbiome alteration remains to be further explored.

Environmental Factors, Gut Microbiota, and Colorectal Cancer Prevention

The substantial burden of colorectal cancer and increasing trend in young adults highlight the importance of lifestyle modification as a complement to screening for colorectal cancer prevention. Several dietary and lifestyle factors have been implicated in the development of colorectal cancer, possibly through the intricate metabolic and inflammatory mechanisms. Likewise, as a key metabolic and immune regulator, the gut microbiota has been recognized to play an important role in colorectal tumorigenesis. Increasing data support that environmental factors are crucial determinants for the gut microbial composition and function, whose alterations induce changes in the host gene expression, metabolic regulation, and local and systemic immune response, thereby influencing cancer development. Here, we review the epidemiologic and mechanistic evidence regarding the links between diet and lifestyle and the gut microbiota in the development of colorectal cancer. We focus on factors for which substantial data support their importance for colorectal cancer and their potential role in the gut microbiota, including overweight and obesity, physical activity, dietary patterns, fiber, red and processed meat, marine omega-3 fatty acid, alcohol, and smoking. We also briefly describe other colorectal cancer-preventive factors for which the links with the gut microbiota have been suggested but remain to be mechanistically characterized, including vitamin D status, dairy consumption, and metformin use. Given limitations in available evidence, we highlight the need for further investigations in the relationship between environmental factors, gut microbiota, and colorectal cancer, which may lead to development and clinical translation of potential microbiota-based strategies for cancer prevention.

Nanozyme-Mediated Dual Immunoassay Integrated with Smartphone for Use in Simultaneous Detection of Pathogens

Nanozymes are an excellent class of optical reporters for the development of sensitive biosensors for widespread applications. In this study, mesoporous core-shell palladium@platinum (Pd@Pt) nanoparticles were synthesized and then applied as signal amplifier in a dual lateral flow immunoassay (LFIA) and integrated with a smartphone-based device for use in simultaneous detection of Salmonella Enteritidis and Escherichia coli O157:H7. After optimization, the limit of detections were calculated to be ∼20 cfu/mL for S. Enteritidis and ∼34 cfu/mL for E. coli O157:H7, respectively. The greatly improved sensitivity was contributed by the peroxidase-like catalytic activity of the Pd@Pt nanoparticles for signal enhancement and the parallel design of dual detection for eliminating the cross-interference. The estimated recoveries of the dual LFIA range from 91.44 to 117.00%, which indicated that the developed method is capable of detecting live bacteria in food samples. This approach provides an attractive platform for S. Enteritidis and E. coli O157:H7 detection using a smartphone-based device as the sole piece of equipment, indicating great promise for foodborne pathogen analysis or in-field food safety tracking.

Emerging pathogenic links between microbiota and the gut-lung axis

The microbiota is vital for the development of the immune system and homeostasis. Changes in microbial composition and function, termed dysbiosis, in the respiratory tract and the gut have recently been linked to alterations in immune responses and to disease development in the lungs. In this Opinion article, we review the microbial species that are usually found in healthy gastrointestinal and respiratory tracts, their dysbiosis in disease and interactions with the gut-lung axis. Although the gut-lung axis is only beginning to be understood, emerging evidence indicates that there is potential for manipulation of the gut microbiota in the treatment of lung diseases.