Contributions of the intestinal microbiome in lung immunity

Gut microbiota: Role and Association with Tumorigenesis in Different Malignancies

The microbiota has been associated with different cancer and may vary from patient to patient. A specific microbial strain can alter the progression of cancer and therapeutic outcome in response to anti-cancer therapy. The variations in microbiota contributed due to the individual microbiome of the microorganism are responsible for diverse clinical outcomes. The expansion of microbiota subpopulation during dysbiosis can lead to toxin production, inducing inflammation and cancer. The microbiota can be a dual-edged sword because it can be tumor-suppressive or oncogenic in the case of the gut. The transition of cancer cells from early to late-stage also impacts the composition of the microbiota, and this alteration could change the behavior of cancer. Multi-omics platforms derived data from an individual's multi-dimensional data (DNA, mRNA, microRNA, protein, metabolite, microbiota, and microbiome), i.e., individualome, to exploit it for personalized tailored treatment for different cancers in a precise manner. A number of studies suggest the importance of microbiota and its add-in suitability to existing treatment options for different malignancies. Furthermore, in vitro, and in vivo studies and cancer clinical trials suggest that probiotics have driven modulation of gut microbiota and other sites discourage the aggressive behavior and progression of different cancers.

The Relationship between Gut Microbiota and Respiratory Tract Infections in Childhood: A Narrative Review

Respiratory tract infections (RTIs) are common in childhood and represent one of the main causes of hospitalization in this population. In recent years, many studies have described the association between gut microbiota (GM) composition and RTIs in animal models. In particular, the “inter-talk” between GM and the immune system has recently been unveiled. However, the role of GM in human, and especially infantile, RTIs has not yet been fully established. In this narrative review we provide an up-to-date overview of the physiological pathways that explain how the GM shapes the immune system, potentially influencing the response to common childhood respiratory viral infections and compare studies analysing the relationship between GM composition and RTIs in children. Most studies provide evidence of GM dysbiosis, but it is not yet possible to identify a distinct bacterial signature associated with RTI predisposition. A better understanding of GM involvement in RTIs could lead to innovative integrated GM-based strategies for the prevention and treatment of RTIs in the paediatric population.

Alteration of the gut microbiota's composition and metabolic output correlates with COVID-19-like severity in obese NASH hamsters

Obese patientss with nonalcoholic steatohepatitis (NASH) are particularly prone to developing severe forms of coronavirus disease 19 (COVID-19). The gut-to-lung axis is critical during viral infections of the respiratory tract, and a change in the gut microbiota's composition might have a critical role in disease severity. Here, we investigated the consequences of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on the gut microbiota in the context of obesity and NASH. To this end, we set up a nutritional model of obesity with dyslipidemia and NASH in the golden hamster, a relevant preclinical model of COVID-19. Relative to lean non-NASH controls, obese NASH hamsters develop severe inflammation of the lungs and liver. 16S rRNA gene profiling showed that depending on the diet, SARS-CoV-2 infection induced various changes in the gut microbiota's composition. Changes were more prominent and transient at day 4 post-infection in lean animals, alterations still persisted at day 10 in obese NASH animals. A targeted, quantitative metabolomic analysis revealed changes in the gut microbiota's metabolic output, some of which were diet-specific and regulated over time. Our results showed that specifically diet-associated taxa are correlated with disease parameters. Correlations between infection variables and diet-associated taxa highlighted a number of potentially protective or harmful bacteria in SARS-CoV-2-infected hamsters. In particular, some taxa in obese NASH hamsters (e.g. Blautia and Peptococcus) were associated with pro-inflammatory parameters in both the lungs and the liver. These taxon profiles and their association with specific disease markers suggest that microbial patterns might influence COVID-19 outcomes.

Polyphenols from Chinese Herbal Medicine: Molecular Mechanisms and Therapeutic Targets in Pulmonary Fibrosis

Pulmonary fibrosis (PF) is a highly confounding and fatal pathological process with finite treatment options. Multiple factors such as oxidative and immune/inflammation involve key pathological processes in chronic lung disease, and their intimate interactions mediate chronic lung damage, denudation of the alveolar epithelium, hyperproliferation of type II alveolar epithelial cells (AECIIs), proliferation and differentiation of fibroblasts, and the permeability of microvessels. We reviewed the classic mechanism of PF and highlighted a few emerging mechanisms for studying complex networks in lung disease pathology. Polyphenols, as a multi-target drug, has excellent potential in the treatment of pulmonary fibrosis. We then reviewed recent advances in discovering phenolic compounds from fruits, tea, and medical herbs with the bioactivities of simultaneously regulating multiple factors (e.g., oxidative stress, inflammation, autophagy, apoptosis, pyroptosis) for minimizing pulmonary fibrosis injury. These compounds include resveratrol, curcumin, salvianolic acid B, epigallocatechin-3-gallate, gallic acid, corilagin. Each phenolic compound can exert its anti-PF effect through various mechanisms, and the signaling pathways involved in different phenolic compounds are not the same. This review summarized the available evidence on phenolic compounds' effectiveness in pulmonary diseases and explored the molecular mechanisms and therapeutic targets of phenolic compounds from Chinese herbal medicine with the properties of inhibition of ongoing fibrogenesis and resolution of existing fibrosis.

Emerging trends and hotspot in gut-lung axis research from 2011 to 2021: a bibliometrics analysis

BACKGROUND

Increasing attention has been paid to the potential relationship between gut and lung. The bacterial dysbiosis in respiratory tract and intestinal tract is related to inflammatory response and the progress of lung diseases, and the pulmonary diseases could be improved by regulating the intestinal microbiome. This study aims to generate the knowledge map to identify major the research hotspots and frontier areas in the field of gut-lung axis.

MATERIALS AND METHODS

Publications related to the gut-lung axis from 2011 to 2021 were identified from the Web of Science Core Collection. CiteSpace 5.7.R2 software was used to analyze the publication years, journals, countries, institutions, and authors. Reference co-citation network has been plotted, and the keywords were used to analyze the research hotspots and trends.

RESULTS

A total of 3315 publications were retrieved and the number of publications per year increased over time. Our results showed that Plos One (91 articles) was the most active journal and The United States (1035 articles) published the most articles. We also observed the leading institution was the University of Michigan (48 articles) and Huffnagle Gary B, Dickson Robert P and Hansbro Philip M, who have made outstanding contributions in this field.

CONCLUSION

The Inflammation, Infection and Disease were the hotspots, and the regulation of intestinal flora to improve the efficacy of immunotherapy in lung cancer was the research frontier. The research has implications for researchers engaged in gut-lung axis and its associated fields.

Immunonutrition and SARS-CoV-2 Infection in Children with Obesity

Since the beginning of the SARS-CoV-2 pandemic, there has been much discussion about the role of diet and antiviral immunity in the context of SARS-CoV-2 infection. Intake levels of vitamins D, C, B12, and iron have been demonstrated to be correlated with lower COVID-19 incidence and mortality. Obesity has been demonstrated to be an independent risk for the severity of COVID-19 infection in adults and also in children. This may be due to different mechanisms, mainly including the gut dysbiosis status observed in obese children. Moreover, the existence of a gut-lung axis added new knowledge to on the potential mechanisms by which diet and dietary substances may affect immune function. The aim of this narrative review is to address the intricate inter-relationship between COVID-19, immune function, and obesity-related inflammation and to describe the role of nutrients and dietary patterns in enhancing the immune system. Two ways to fight against COVID-19 disease exist: one with an antiviral response through immune system boosting and another with antioxidants with an anti-inflammatory effect. In the current pandemic situation, the intake of a varied and balanced diet, rich in micronutrients and bioactive compounds including fibers, should be recommended. However, clinical studies conducted on children affected by SARS-CoV-2 infection and comorbidity are warranted.

The potential application of probiotics for the prevention and treatment of COVID-19

Background

Given the severe infection, poor prognosis, and the low number of available effective drugs, potential prevention and treatment strategies for COVID-19 need to be urgently developed.

Main body

Herein, we present and discuss the possible protective and therapeutic mechanisms of human microbiota and probiotics based on the previous and recent findings. Microbiota and probiotics consist of mixed cultures of living microorganisms that can positively affect human health through their antiviral, antibacterial, anti-inflammatory, and immunomodulatory effect. In the current study, we address the promising advantages of microbiota and probiotics in decreasing the risk of COVID-19.

Conclusions

Thus, we recommend further studies be conducted for assessing and evaluating the capability of these microbes in the battle against COVID-19.

Intestinal Flora: A Potential Mechanism by Which Yinlai Decoction Treats Lipopolysaccharide-Induced Pneumonia

Background. We intended to explore the mechanism of Yinlai decoction in the treatment of lipopolysaccharide (LPS)-induced pneumonia from the perspective of intestinal flora. Methods. Thirty Sprague–Dawley rats were randomly assigned to the blank control group (N), the pneumonia group (P), and the Yinlai decoction group (PT). The rat pneumonia model was established using LPS inhalation (0.5 mg/mL, 5 mL, 30 min/day, 3 days). Yinlai decoction was administered intragastrically (2 mL/100 g, 3 days). Lung tissue pathology, organ indexes, serum inflammatory factors, tumor necrosis factor-alpha (TNF-α), and intestinal flora changes were measured. Results. Lung tissue inflammation was prevented by Yinlai decoction. IL-6 levels showed a higher tendency to be higher, and IL-12 and TNF-α were significantly higher in the PT group than in the P group. The structure of the intestinal flora in the P differed from that in the N. The relative abundance of 10 out of 12 microflora was significantly higher in the P group than in the N and PT groups. In the PT group, the structure and the distribution of microbial groups were like those of the N group. Conclusions. Yinlai decoction inhibited LPS-induced lung and systemic inflammation in rats and may help the intestinal flora restore equilibrium by inhibiting the colonization of pathogenic bacteria and adjusting the ratio between probiotics and pathogenic bacteria. Intestinal flora may serve as a mediator of Yinlai decoction’s effect on LPS-induced pneumonia.

Bacillus-Based Direct-Fed Microbial Reduces the Pathogenic Synergy of a Coinfection with Salmonella enterica Serovar Choleraesuis and Porcine Reproductive and Respiratory Syndrome Virus

Viral respiratory infections predispose lungs to bacterial coinfections causing a worse outcome than either infection alone. Porcine reproductive and respiratory syndrome virus (PRRSV) causes pneumonia in pigs and is often associated with bacterial coinfections. We examined the impact of providing weanling pigs a Bacillus-based direct-fed microbial (DFM) on the syndrome resulting from infection with either Salmonella enterica serotype Choleraesuis alone, or in combination with PRRSV. Nine days after the bacterial challenge, Salmonella was isolated from ileocecal lymph nodes of all challenged pigs regardless of DFM treatment. Compared to the single bacterial challenge, the dual challenge with Salmonella and PRRSV resulted in a pathogenic synergy exhibited by a higher rate of Salmonella colonization in the lung and a more extensive and severe interstitial pneumonia. Provision of DFM to dually challenged pigs reduced the rate of lung colonization by Salmonella, eliminated or reduced the presence of PRRSV in the lung, and reduced the extent and severity of gross lung pathology. Dually challenged pigs that received DFM had increased concentrations of interleukin 1 (IL-1) and IL-8 in lung lavage fluids, accompanied by increased expression in their blood cells of nucleotide-binding oligomerization domain receptor 2 (NOD2) and triggering receptor expressed in myeloid cells 1 (TREM-1) molecules. These changes in pulmonary inflammatory cytokine production and increased expression of NOD2 and TREM-1 suggest that the DFM exerted a systemic modulating effect on innate immunity. These observations are consistent with the notion that tonic stimulation by gut-derived microbial products can poise innate immunity to fight infections in the respiratory tract.

Gut microbiota dynamics in a prospective cohort of patients with post-acute COVID-19 syndrome

BACKGROUND

Long-term complications after COVID-19 are common, but the potential cause for persistent symptoms after viral clearance remains unclear.

OBJECTIVE

To investigate whether gut microbiome composition is linked to post-acute COVID-19 syndrome (PACS), defined as at least one persistent symptom 4 weeks after clearance of the SARS-CoV-2 virus.

METHODS

We conducted a prospective study of 106 patients with a spectrum of COVID-19 severity followed up from admission to 6 months and 68 non-COVID-19 controls. We analysed serial faecal microbiome of 258 samples using shotgun metagenomic sequencing, and correlated the results with persistent symptoms at 6 months.

RESULTS

At 6 months, 76% of patients had PACS and the most common symptoms were fatigue, poor memory and hair loss. Gut microbiota composition at admission was associated with occurrence of PACS. Patients without PACS showed recovered gut microbiome profile at 6 months comparable to that of non-COVID-19 controls. Gut microbiome of patients with PACS were characterised by higher levels of Ruminococcus gnavus, Bacteroides vulgatus and lower levels of Faecalibacterium prausnitzii. Persistent respiratory symptoms were correlated with opportunistic gut pathogens, and neuropsychiatric symptoms and fatigue were correlated with nosocomial gut pathogens, including Clostridium innocuum and Actinomyces naeslundii (all p<0.05). Butyrate-producing bacteria, including Bifidobacterium pseudocatenulatum and Faecalibacterium prausnitzii showed the largest inverse correlations with PACS at 6 months.

CONCLUSION

These findings provided observational evidence of compositional alterations of gut microbiome in patients with long-term complications of COVID-19. Further studies should investigate whether microbiota modulation can facilitate timely recovery from post-acute COVID-19 syndrome.

Gastrointestinal Symptoms Predict the Outcomes From COVID-19 Infection

Coronavirus disease 2019 (COVID-19) has taken hundreds of thousands of lives globally. Besides the respiratory tract, the virus can affect the gastrointestinal (GI) tract. Data regarding the significance of GI symptoms in the COVID-19 course are limited. In this largest US study to date, the authors reviewed electronic encounters of 1003 consecutive patients who were tested positive for the virus between March 12 and April 3, 2020. Initial GI symptoms were present in up to 22.4% of patients and were associated with worse outcomes after adjustment for demographics, comorbidities, and other clinical symptoms. COVID-19 with GI involvement may define a more severe phenotype.

Yanning Syrup ameliorates the lipopolysaccharide-induced inflammation: Adjusting the gut microbiota, short-chain fatty acids, and the CD4+ T cell balance

ETHNOPHARMACOLOGICAL RELEVANCE

As a commercial Chinese patent medicine, Yanning Syrup (YN) is used to treat acute upper respiratory tract infections and acute enteritis effectively in clinical practice. However, the underlying mechanism remains unclear.

AIMS OF THE STUDY

To reveal the effect of YN on gut microbiota dysbiosis, and explore the potential role of the gut microecosystem and CD4⁺ T cell immune homeostasis in YN-treated respiratory and intestinal diseases in lipopolysaccharide (LPS)-induced inflammatory rats.

METHODS

Inflammation in rat models was induced by intraperitoneal injection of LPS (8 mg/kg). Histological changes were observed by H & E staining. Changes in gut microbiota and short-chain fatty acid (SCFA) production were analysed using 16S rRNA gene sequencing and targeted metabolomics. A Luminex cytokine microarray and enzyme-linked immunosorbent assay (ELISA) were conducted to evaluate the serum and colon cytokine profiles. The frequencies of immune cells, including Th1, Th2, Th17 and Treg cells in the mesenteric lymph nodes (MLNs), bronchoalveolar lavage fluid (BALF) and whole blood were phenotyped using flow cytometry.

RESULTS

The YN-treated rats showed less colon inflammation, as evidenced by the reduction in mortality rate and histology score. Notably, YN was found to improve the immunosuppressed state induced by LPS in rats, which not only upregulated the levels of the proinflammatory cytokine IL-17A and the immunosuppressive cytokines IL-4 and IL-10 in colon tissue but also increased the levels of IL-1α, IL-5, IL-7, IL-12 (p70), GM-CSF and VEGF in serum. The numbers of Th17 cells and Treg cells in the MLNs, blood, and BALF of model rats were regulated by YN, with the restoration of the Th17/Treg balance. Additionally, the Th1/Th2 balance in MLNs and whole blood of model rats was restored after YN administration. Sequencing of 16S rRNA gene indicated that YN-treated rats exhibited greater gut microbial diversity and flora composition, specifically inhibiting some harmful bacteria such as Enterobacter and Blautia and increasing Firmicutes and Actinobacteria. Targeted metabolomics analysis demonstrated an increase of SCFA (acetic acid, butyric acid, valeric acid, and hexanoic acid) production in YN-treated rats. Most of the dominant bacterial genera regulated by YN administration were correlated with the concentrations of SCFA and inflammatory cytokines.

CONCLUSIONS

These results demonstrated that YN could ameliorate LPS-induced inflammation in rats by modifying gut microbiota, increasing microbiota-derived SCFA production and regulating the balance of Th1/Th2 and Treg/Th17 cells.

Relationship between gut microbiota and lung function decline in patients with chronic obstructive pulmonary disease: a 1-year follow-up study

OBJECTIVE

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory lung disease characterized by a persistent limitation in airflow. Gut microbiota is closely correlated with lung inflammation. However, gut microbiota has not been studied in patients with declining lung function, due to chronic lung disease progression.

SUBJECTS AND METHODS

Stool samples were obtained from 55 patients with COPD that were in stable condition at enrolment (stage 1) and at a 1-year follow-up (stage 2). After extracting stool DNA, we performed next generation sequencing to analyse the distribution of gut microbiota.

RESULTS

Patients were divided to control and declining lung function groups, based on whether the rate of forced expiratory volume in 1 s (FEV₁) had declined over time. An alpha diversity analysis of initial and follow-up stool samples showed a significant difference in the community richness of microbiota in the declining function group, but not in the control group. At the phylum level, Bacteroidetes was more abundant in the control group and Firmicutes was more abundant in the declining function group. The Alloprevotella genus was more abundant in the control group than in the declining function group. At 1-year follow-up, the mean proportions of Acinetobacter and Stenotrophomonas significantly increased in the control and declining function groups, respectively.

CONCLUSION

Some community shifts in gut microbiota were associated with lung function decline in COPD patients under regular treatment. Future studies should investigate the mechanism underlying alterations in lung function, due to changes in gut bacterial communities, in COPD.

Leptin in the Respiratory Tract: Is There a Role in SARS-CoV-2 Infection?

Leptin is a pleiotropic adipocytokine involved in several physiologic functions, with a known role in innate and adaptive immunity as well as in tissue homeostasis. Long- and short-isoforms of leptin receptors are widely expressed in many peripheral tissues and organs, such as the respiratory tract. Similar to leptin, microbiota affects the immune system and may interfere with lung health through the bidirectional crosstalk called the “gut-lung axis.” Obesity leads to impaired protective immunity and altered susceptibility to pulmonary infections, as those by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although it is known that leptin and microbiota link metabolism and lung health, their role within the SARS-CoV2 coronavirus disease 2019 (COVID-19) deserves further investigations. This review aimed to summarize the available evidence about: (i) the role of leptin in immune modulation; (ii) the role of gut microbiota within the gut-lung axis in modulating leptin sensitivity; and (iii) the role of leptin in the pathophysiology of COVID-19.

Alteration of the gut microbiota following SARS-CoV-2 infection correlates with disease severity in hamsters

Mounting evidence suggests that the gut-to-lung axis is critical during respiratory viral infections. We herein hypothesized that disruption of gut homeostasis during severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection may associate with early disease outcomes. To address this question, we took advantage of the Syrian hamster model. Our data confirmed that this model recapitulates some hallmark features of the human disease in the lungs. We further showed that SARS-CoV-2 infection associated with mild intestinal inflammation, relative alteration in intestinal barrier property and liver inflammation and altered lipid metabolism. These changes occurred concomitantly with an alteration of the gut microbiota composition over the course of infection, notably characterized by a higher relative abundance of deleterious bacterial taxa such as Enterobacteriaceae and Desulfovibrionaceae. Conversely, several members of the Ruminococcaceae and Lachnospiraceae families, including bacteria known to produce the fermentative products short-chain fatty acids (SCFAs), had a reduced relative proportion compared to non-infected controls. Accordingly, infection led to a transient decrease in systemic SCFA amounts. SCFA supplementation during infection had no effect on clinical and inflammatory parameters. Lastly, a strong correlation between some gut microbiota taxa and clinical and inflammation indices of SARS-CoV-2 infection severity was evidenced. Collectively, alteration of the gut microbiota correlates with disease severity in hamsters making this experimental model valuable for the design of interventional, gut microbiota-targeted, approaches for the control of COVID-19.Abbreviations: SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; COVID-19, coronavirus disease 2019; SCFAs, short-chain fatty acids; dpi, day post-infection; RT-PCR, reverse transcription polymerase chain reaction; IL, interleukin. ACE2, angiotensin converting enzyme 2; TMPRSS2, transmembrane serine protease 2.

Evaluation of early antibiotic use in patients with non-severe COVID-19 without bacterial infection

OBJECTIVES

The use of antibiotics was common in some countries during the early phase of the coronavirus disease 2019 (COVID-19) pandemic, but adequate evaluation remains lacking. This study aimed to evaluate the effect of early antibiotic use in patients with non-severe COVID-19 admitted without bacterial infection.

METHODS

This multi-centre retrospective cohort study included 1,373 inpatients with non-severe COVID-19 admitted without bacterial infection. Patients were divided into two groups according to their exposure to antibiotics within 48 h of admission. The outcomes were progression to severe COVID-19, length of stay >15 days and mortality rate. A mixed-effect Cox model and random effect logistic regression were used to explore the association between early antibiotic use and outcomes.

RESULTS

During the 30-day follow-up period, the proportion of patients who progressed to severe COVID-19 in the early antibiotic use group was almost 1.4 times that of the comparison group. In the mixed-effect model, the early use of antibiotics was associated with higher probability of developing severe COVID-19 and staying in hospital for >15 days. However, there was no significant association between early use of antibiotics and mortality. Analysis with propensity-score-matched cohorts displayed similar results. In subgroup analysis, patients receiving any class of antibiotic were at increased risk of adverse health outcomes. Azithromycin did not improve disease progression and length of stay in patients with COVID-19.

CONCLUSIONS

It is suggested that antibiotic use should be avoided unless absolutely necessary in patients with non-severe COVID-19, particularly in the early stages.

Gut Microbiota and SCFAs Play Key Roles in QingFei Yin Recipe Anti-Streptococcal Pneumonia Effects

Emerging evidence has revealed the presence in animals of a bidirectional regulatory “lung-gut axis” that provides resistance to respiratory infections. Clues to the existence of this system stem from observations that respiratory infections are often accompanied by gastrointestinal symptoms, whereby intestinal microbiota appear to play pivotal roles in combating pathogenic infections. Importantly, short-chain fatty acids (SCFAs) produced by the gut microbiota appear to serve as the biological link between host immune defenses and gut flora. Streptococcus pneumoniae (S.pn), the main cause of lower respiratory tract infections, is involved in more than 1.189 million deaths per year. QingFei Yin (QFY) is known for its excellent therapeutic efficacy in combating bacterial lung infections. In this study, effects of S.pn infection on gut homeostasis were assessed using 16S RNA-based microbiota community profiling analysis. In addition, potential mechanisms underlying QFY recipe beneficial therapeutic effects against bacterial pneumonia were explored using S.pn-infected gut microbiota-depleted mice. Results of data analysis indicated that QFY treatment alleviated lung infection-associated pathogenic processes, while also promoting repair of disordered gut flora and counteracting S.pn infection-associated decreases in levels of SCFAs, particularly of acetate and butyrate. Mechanistically, QFY treatment suppressed inflammatory lung injury through inhibition of the host NF-κB-NLRP3 pathway. These results inspired us to identify precise QFY targets and mechanisms underlying QFY anti-inflammatory effects. In addition, we conducted an in-depth evaluation of QFY as a potential treatment for bacterial pneumonia.

Risk factors of early postoperative bowel obstruction for patients undergoing selective colorectal surgeries

OBJECTIVE

Postoperative bowel obstruction was one of the most severe complications in patients who received colorectal surgeries. This study aimed to explore risk factors of early postoperative obstruction and to construct a nomogram to predict the possibility of occurrence.

METHODS

The records of 1437 patients who underwent elective colorectal surgery in Peking University People's Hospital from 2015 to 2020 were retrospectively collected. Risk factors of early postoperative bowel obstruction were identified by logistic regression analysis and a nomogram was then constructed. Bootstrap was applied to verify the stability of the model.

RESULTS

COPD, hypothyroidism, probiotic indications, duration of antibiotics, and time to postoperative feeding were identified as independent risk factors and were put into a nomogram for predicting early postoperative bowel obstruction. The nomogram showed robust discrimination, with the area under the receiver operating characteristic curve was 0.894 and was well-calibrated.

CONCLUSION

A nomogram including independent risk factors of COPD, hypothyroidism, probiotic indications, duration of antibiotics, and time to postoperative feeding were established to predict the risk of early postoperative bowel obstruction.

Diet and Risk of Incident Lung Cancer: A Large Prospective Cohort Study in UK Biobank

BACKGROUND

Epidemiological evidence remains conflicting regarding diet and risk of lung cancer.

OBJECTIVES

We sought to systematically investigate whether dietary factors are associated with the risk of incident lung cancer in the UK Biobank.

METHODS

A total of 416,588 participants (54% women) from the UK Biobank were included in the present study. Based on baseline data from FFQs, 3 main dietary patterns were identified by using principal component analysis. Cox proportional hazards models were used to investigate the association of individual food groups and dietary patterns with lung cancer risk.

RESULTS

During a median follow-up of 7.13 y, 1782 incident lung cancer cases were documented. The association analysis showed high intake of red meat and processed meat was associated with an increased risk of lung cancer (HRper 50 g/d: 1.36; 95% CI: 1.13, 1.65 for red meat; HRper 25 g/d: 1.30; 95% CI: 1.10, 1.53 for processed meat). However, the consumption of fruits (HRper 100 g/d: 0.90; 95% CI: 0.84, 0.95), vegetables (HRper 100 g/d: 0.89; 95% CI: 0.81, 0.99), breakfast cereals (HRper 50 g/d: 0.81; 95% CI: 0.74, 0.89), and dietary fiber (HRper 5 g/d: 0.76; 95% CI: 0.69, 0.84) was inversely associated with the risk of lung cancer. For the dietary pattern analysis [quartile (Q) comparison], high adherence to the Prudent pattern (HRQ4 compared with Q1: 0.84; 95% CI: 0.73, 0.96) was associated with a lower risk of lung cancer, whereas the Western pattern (HRQ4 compared with Q1: 1.27; 95% CI: 1.11, 1.46) was associated with a higher risk of lung cancer.

CONCLUSIONS

Our study indicated that a diet characterized by high intake of fruits, vegetables, breakfast cereals, and dietary fiber, as well as low intake of red meat and processed meat, was associated with a lower risk of lung cancer.

The Role of Gut and Lung Microbiota in Susceptibility to Tuberculosis

Tuberculosis is one of the most common infectious diseases and infectious causes of death worldwide. Over the last decades, significant research effort has been directed towards defining the understanding of the pathogenesis of tuberculosis to improve diagnosis and therapeutic options. Emerging scientific evidence indicates a possible role of the human microbiota in the pathophysiology of tuberculosis, response to therapy, clinical outcomes, and post-treatment outcomes. Although human studies on the role of the microbiota in tuberculosis are limited, published data in recent years, both from experimental and clinical studies, suggest that a better understanding of the gut-lung microbiome axis and microbiome-immune crosstalk could shed light on the specific pathogenetic mechanisms of Mycobacterium tuberculosis infection and identify new therapeutic targets. In this review, we address the current knowledge of the host immune responses against Mycobacterium tuberculosis infection, the emerging evidence on how gut and lung microbiota can modulate susceptibility to tuberculosis, the available studies on the possible use of probiotic-antibiotic combination therapy for the treatment of tuberculosis, and the knowledge gaps and future research priorities in this field.

Pediatric Obesity-Related Asthma: The Role of Nutrition and Nutrients in Prevention and Treatment

Childhood obesity rates have dramatically risen in numerous countries worldwide. Obesity is likely a factor in increased asthma risk, which is already one of the most widespread chronic respiratory pathologies. The pathogenic mechanism of asthma risk has still not yet been fully elucidated. Moreover, the role of obesity-related inflammation and pulmonary overreaction to environmental triggers, which ultimately result in asthma-like symptoms, and the importance of dietary characteristics is well recognized. Diet is an important adjustable element in the asthma development. Food-specific composition of the diet, in particular fat, sugar, and low-quality nutrients, is likely to promote the chronic inflammatory state seen in asthmatic patients with obesity. An unbalanced diet or supplementation as a way to control asthma more efficiently has been described. A personalized dietary intervention may improve respiratory symptoms and signs and therapeutic response. In this narrative review, we presented and discussed more recent literature on asthma associated with obesity among children, focusing on the risk of asthma among children with obesity, asthma as a result of obesity focusing on the role of adipose tissue as a mediator of systemic and local airway inflammation implicated in asthma regulation, and the impact of nutrition and nutrients in the development and treatment of asthma. Appropriate early nutritional intervention could possibly be critical in preventing and managing asthma associated with obesity among children.

Role of Gut Microbiome in COVID-19: An Insight Into Pathogenesis and Therapeutic Potential

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), resulted in an unprecedented global crisis. Although primarily a respiratory illness, dysregulated immune responses may lead to multi-organ dysfunction. Prior data showed that the resident microbial communities of gastrointestinal and respiratory tracts act as modulators of local and systemic inflammatory activity (the gut-lung axis). Evolving evidence now signals an alteration in the gut microbiome, brought upon either by cytokines from the infected respiratory tract or from direct infection of the gut, or both. Dysbiosis leads to a "leaky gut". The intestinal permeability then allows access to bacterial products and toxins into the circulatory system and further exacerbates the systemic inflammatory response. In this review, we discuss the available data related to the role of the gut microbiome in the development and progression of COVID-19. We provide mechanistic insights into early data with a focus on immunological crosstalk and the microbiome's potential as a biomarker and therapeutic target.

A Modern-World View of Host-Microbiota-Pathogen Interactions

The microbiota-the diverse set of commensal microbes that normally colonize humans-represents the first line of defense against infectious diseases. In this review, we summarize the direct and indirect mechanisms by which the microbiota modulates susceptibility to, and severity of, infections, with a focus on immunological mechanisms. Moreover, we highlight some of the ways that modern-world lifestyles have influenced the structure-function relationship between the microbiota and infectious diseases. Ultimately, understanding how the microbiota influences infectious risks will facilitate development of microbiota-derived therapeutics that bolster host defenses.

Microbiome in Critical illness: An Unconventional and Unknown Ally

BACKGROUND

The digestive tract represents an interface between the external environment and the body where the interaction of a complex polymicrobial ecology has an important influence on health and disease. The physiological mechanisms that are altered during the hospitalization and in the intensive care unit (ICU) contribute to the pathobiota's growth. Intestinal dysbiosis occurs within hours of being admitted to ICU. This may be due to different factors, such as alterations of normal intestinal transit, administration of variuos medications or alterations in the intestinal wall which causes a cascade of events that will lead to the increase of nitrates and decrease of oxygen concentration, liberation of free radicals.

OBJECTIVE

This work aims to report the latest updates on the microbiota's contribution to developing sepsis in patients in the ICU department. In this short review were reviewed the latest scientific findings on the mechanisms of intestinal immune defenses performed both locally and systemically. In addition, we considered it necessary to review the literature to report the current best treatment strategies to prevent the infection spread which can bring systemic infections in patients admitted to ICU.

MATERIAL AND METHODS

This review has been written to answer at three main questions: what are the main intestinal flora's defense mechanisms that help us to prevent the risk of developing systemic diseases on a day-to-day basis? What are the main dysbiosis' systemic abnormalities? What are the modern strategies that are used in the ICU patients to prevent the infection spread? Using the combination of following keywords: microbiota and ICU, ICU and gut, microbiota and critical illness, microbiota and critical care, microbiota and sepsis, microbiota and infection, gastrointestinal immunity,in the Cochrane Controlled Trials Register, the Cochrane Library, medline and pubmed, google scholar, ovid/wiley. Finally, we reviewed and selected 72 articles. We also consulted the site ClinicalTrials.com to find out studies that are recently conducted or ongoing.

RESULTS

The critical illness can alter intestinal bacterial flora leading to homeostasis disequilibrium. Despite numerous mechanisms, such as epithelial cells with calciform cells that together build a mechanical barrier for pathogenic bacteria, the presence of mucous associated lymphoid tissue (MALT) which stimulates an immune response through the production of interferon-gamma (IFN-y) and THN-a or by stimulating lymphocytes T helper-2 produces anti-inflammatory cytokines. But these defenses can be altered following a hospitalization in ICU and lead to serious complications such as acute respiratory distress syndrome (ARDS), health care associated pneumonia (HAP) and ventilator associated pneumonia (VAP), Systemic infection and multiple organ failure (MOF), but also in the development of coronary artery disease (CAD). In addition, the microbiota has a significant impact on the development of intestinal complications and the severity of the SARS-COVID-19 patients.

CONCLUSION

The microbiota is recognized as one of the important factors that can worsen the clinical conditions of patients who are already very frailty in intensive care unit. At the same time, the microbiota also plays a crucial role in the prevention of ICU associated complications. By using the resources, we have available, such as probiotics, symbiotics or fecal microbiota transplantation (FMT), we can preserve the integrity of the microbiota and the GUT, which will later help maintain homeostasis in ICU patients.

Coronavirus disease-19 and the gut-lung axis

Gastrointestinal and respiratory tract diseases often occur together. There are many overlapping pathologies, leading to the concept of the ‘gut–lung axis’ in which stimulation on one side triggers a response on the other side. This axis appears to be implicated in infections involving severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which has triggered the global coronavirus disease 2019 (COVID-19) pandemic, in which respiratory symptoms of fever, cough and dyspnoea often occur together with gastrointestinal symptoms such as nausea, vomiting, abdominal pain and diarrhoea. Besides the gut–lung axis, it should be noted that the gut participates in numerous axes which may affect lung function, and consequently the severity of COVID-19, through several pathways. This article focuses on the latest evidence and the mechanisms that drive the operation of the gut–lung axis, and discusses the interaction between the gut–lung axis and its possible involvement in COVID-19 from the perspective of microbiota, microbiota metabolites, microbial dysbiosis, common mucosal immunity and angiotensin-converting enzyme II, raising hypotheses and providing methods to guide future research on this new disease and its treatments.

The in vitro and in vivo anti-virulent effect of organic acid mixtures against Eimeria tenella and Eimeria bovis

Eimeria tenella and Eimeria bovis are complex parasites responsible for the condition of coccidiosis, that invade the animal gastrointestinal intestinal mucosa causing severe diarrhoea, loss of appetite or abortions, with devastating impacts on the farming industry. The negative impacts of these parasitic infections are enhanced by their role in promoting the colonisation of the gut by common foodborne pathogens. The aim of this study was to test the anti-Eimeria efficacy of maltodextrin, sodium chloride, citric acid, sodium citrate, silica, malic acid, citrus extract, and olive extract individually, in vitro and in combination, in vivo. Firstly, in vitro infection models demonstrated that antimicrobials reduced (p < 0.05), both singly and in combination (AG), the ability of E. tenella and E. bovis to infect MDBK and CLEC-213 epithelial cells, and the virulence reduction was similar to that of the anti-coccidial drug Robenidine. Secondly, using an in vivo broiler infection model, we demonstrated that AG reduced (p = 0.001) E. tenella levels in the caeca and excreted faeces, reduced inflammatory oxidative stress, improved the immune response through reduced ROS, increased Mn-SOD and SCFA levels. Levels of IgA and IgM were significantly increased in caecal tissues of broilers that received 0.5% AG and were associated with improved (p < 0.0001) tissue lesion scores. A prophylactic approach increased the anti-parasitic effect in vivo, and results indicated that administration from day 0, 5 and 10 post-hatch reduced tissue lesion scores (p < 0.0001) and parasite excretion levels (p = 0.002). Conclusively, our in vitro and in vivo results demonstrate that the natural antimicrobial mixture (AG) reduced parasitic infections through mechanisms that reduced pathogen virulence and attenuated host inflammatory events.

COVID-19 infection and liver injury: Clinical features, biomarkers, potential mechanisms, treatment, and management challenges

It is hypothesized that liver impairment caused by coronavirus disease 2019 (COVID-19) infection might play a central role in severe clinical presentations. Liver injury is closely associated with severe disease and, even with antiviral drugs, have a poor prognosis in COVID-19 patients. In addition to the common hepatobiliary disorders caused by COVID-19, patients with pre-existing liver diseases demand special considerations during the current pandemic. Thus, it is vital that upon clinical presentation, patients with concurrent pre-existing liver disease associated with metabolic dysfunction and COVID-19 be managed properly to prevent liver failure. Careful monitoring and early detection of liver damage through biomarkers after hospitalization for COVID-19 is underscored in all cases, particularly in those with pre-existing metabolic liver injury. The purpose of this study was to determine most recent evidence regarding causality, potential risk factors, and challenges, therapeutic options, and management of COVID-19 infection in vulnerable patients with pre-existing liver injury. This review aims to highlight the current frontier of COVID-19 infection and liver injury and the direction of liver injury in these patients.

Host factors facilitating SARS-CoV-2 virus infection and replication in the lungs

SARS-CoV-2 is the virus causing the major pandemic facing the world today. Although, SARS-CoV-2 primarily causes lung infection, a variety of symptoms have proven a systemic impact on the body. SARS-CoV-2 has spread in the community quickly infecting humans from all age, ethnicities and gender. However, fatal outcomes have been linked to specific host factors and co-morbidities such as age, hypertension, immuno-deficiencies, chronic lung diseases or metabolic disorders. A major shift in the microbiome of patients suffering of the coronavirus disease 2019 (COVID-19) have also been observed and is linked to a worst outcome of the disease. As many co-morbidities are already known to be associated with a dysbiosis of the microbiome such as hypertension, diabetes and metabolic disorders. Host factors and microbiome changes are believed to be involved as a network in the acquisition of the infection and the development of the diseases. We will review in detail in this manuscript, the immune response toward SARS-CoV-2 infection as well as the host factors involved in the facilitation and worsening of the infection. We will also address the impact of COVID-19 on the host's microbiome and secondary infection which also worsen the disease.

Transport stress affects the fecal microbiota in healthy donkeys

Background

With the development of large‐scale donkey farming in China, long‐distance transportation has become common practice, and the incidence of intestinal diseases after transportation has increased. The intestinal microbiota is important in health and disease, and whether or not transportation disturbs the intestinal microbiota in donkeys has not been investigated.

Objectives

To determine the effects of transportation on the fecal microbiota of healthy donkeys using 16S rRNA sequencing.

Animals

Fecal and blood samples were collected from 12 Dezhou donkeys before and after transportation.

Methods

Prospective controlled study. Cortisol, ACTH, and heat‐shock protein 90 (HSP90) concentrations were measured. Sequencing of 16S rRNA was used to assess the microbial composition. Alpha diversity and beta diversity were assessed.

Results

Results showed significant (P < .05) increases in cortisol (58.1 ± 14.6 to 71.1 ± 9.60 ng/mL), ACTH (163.8 ± 31.9 to 315.8 ± 27.9 pg/mL), and HSP90 (10.8 ± 1.67 to 14.6 ± 1.75 ng/mL) on the day of arrival. A significantly lower (P = .04) level of bacterial richness was found in fecal samples after transportation, compared with that before transportation without distinct changes in diversity. Most notably, donkeys had significant decreases in Atopostipes, Eubacterium, Streptococcus, and Coriobacteriaceae.

Conclusions and Clinical Importance

Transportation can induce stress in healthy donkeys and have some effect on the composition of the in fecal microbiota. Additional studies are required to understand the potential effect of these microbiota changes, especially significantly decreased bacteria, on the development intestinal diseases in donkeys during recovery from transportation.

Functional lower airways genomic profiling of the microbiome to capture active microbial metabolism

BACKGROUND

Microbiome studies of the lower airways based on bacterial 16S rRNA gene sequencing assess microbial community structure but can only infer functional characteristics. Microbial products, such as short-chain fatty acids (SCFAs), in the lower airways have significant impact on the host's immune tone. Thus, functional approaches to the analyses of the microbiome are necessary.

METHODS

Here we used upper and lower airway samples from a research bronchoscopy smoker cohort. In addition, we validated our results in an experimental mouse model. We extended our microbiota characterisation beyond 16S rRNA gene sequencing with the use of whole-genome shotgun (WGS) and RNA metatranscriptome sequencing. SCFAs were also measured in lower airway samples and correlated with each of the sequencing datasets. In the mouse model, 16S rRNA gene and RNA metatranscriptome sequencing were performed.

RESULTS

Functional evaluations of the lower airway microbiota using inferred metagenome, WGS and metatranscriptome data were dissimilar. Comparison with measured levels of SCFAs shows that the inferred metagenome from the 16S rRNA gene sequencing data was poorly correlated, while better correlations were noted when SCFA levels were compared with WGS and metatranscriptome data. Modelling lower airway aspiration with oral commensals in a mouse model showed that the metatranscriptome most efficiently captures transient active microbial metabolism, which was overestimated by 16S rRNA gene sequencing.

CONCLUSIONS

Functional characterisation of the lower airway microbiota through metatranscriptome data identifies metabolically active organisms capable of producing metabolites with immunomodulatory capacity, such as SCFAs.

Clinical guidelines “Chronic diarrhea in adults”

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Immunonutrition effects on coping with COVID-19

COVID-19 implications are still a threat to global health. In the face of this pandemic, food and nutrition are key issues that can boost the immune system. The bioactivity of functional foods and nutrients (probiotics, prebiotics, water- and fat-soluble vitamins, minerals, flavonoids, glutamine, arginine, nucleotides, and PUFAs) contributes to immune system modulation, which establishes the status of nutrients as a factor of immune competence. These foods can contribute, especially during a pandemic, to the minimization of complications of SARS-CoV-2 infection. Therefore, it is important to support the nutritional strategies for strengthening the immune status, associated with good eating habits, as a way to confront COVID-19.

Pharyngeal Microbial Signatures Are Predictive of the Risk of Fungal Pneumonia in Hematologic Patients

The ability to predict invasive fungal infections (IFI) in patients with hematological malignancies is fundamental for successful therapy. Although gut dysbiosis is known to occur in hematological patients, whether airway dysbiosis also contributes to the risk of IFI has not been investigated. Nasal and oropharyngeal swabs were collected for functional microbiota characterization in 173 patients with hematological malignancies recruited in a multicenter, prospective, observational study and stratified according to the risk of developing IFI. A lower microbial richness and evenness were found in the pharyngeal microbiota of high-risk patients that were associated with a distinct taxonomic and metabolic profile. A murine model of IFI provided biologic plausibility for the finding that loss of protective anaerobes, such as Clostridiales and Bacteroidetes, along with an apparent restricted availability of tryptophan, is causally linked to the risk of IFI in hematologic patients and indicates avenues for antimicrobial stewardship and metabolic reequilibrium in IFI.

Obesity-Induced Dysbiosis Exacerbates IFN-γ Production and Pulmonary Inflammation in the Mycobacterium tuberculosis Infection

The microbiota of the gut-lung axis affects local and far-reaching immune responses and might also trigger chronic and inflammatory diseases. We hypothesized that gut dysbiosis induced by obesity, which coexists in countries with a high tuberculosis burden, aggravates the host susceptibility and the pulmonary damage tolerance. To assess our hypothesis, we used a model of high-fat diet (HFD)-induced obesity, followed by infection of C57BL/6 mice with Mycobacterium tuberculosis. We showed that obesity increased the susceptibility, the pulmonary inflammation and IFN-γ levels in M. tuberculosis-infected mice. During the comorbidity obesity and tuberculosis, there is an increase of Bacteroidetes and Firmicutes in the lungs, and an increase of Firmicutes and butyrate in the feces. Depletion of gut microbiota by antibiotic treatment in the obese infected mice reduced the frequencies of CD4+IFN-γ+IL-17- cells and IFN-γ levels in the lungs, associated with an increase of Lactobacillus. Our findings reinforce the role of the gut-lung axis in chronic infections and suggest that the gut microbiota modulation may be a potential host-directed therapy as an adjuvant to treat TB in the context of IFN-γ-mediated immunopathology.

Gut microbiota in antiviral strategy from bats to humans: a missing link in COVID-19

Bats are a potential natural reservoir for SARS-CoV-2 virus and other viruses detrimental to humans. Accumulated evidence has shown that, in their adaptation to a flight-based lifestyle, remodeling of the gut microbiota in bats may have contributed to immune tolerance to viruses. This evidence from bats provides profound insights into the potential influence of gut microbiota in COVID-19 disease in humans. Here, we highlight recent advances in our understanding of the mechanisms by which the gut microbiota helps bats tolerate deadly viruses, and summarize the current clinical evidence on the influence of gut microbiota on the susceptibility to SARS-CoV-2 infection and risk of COVID-19 leading to a fatal outcome. In addition, we discuss the implications of gut microbiota-targeted approaches for preventing infection and reducing disease severity in COVID-19 patients.

Management of patients with digestive diseases during the COVID-19 pandemic. Clinical Practice Guidelines by the Russian scientific medical society of internal medicine (RSMSIM) and the Gastroenterological Scientific Society of Russia (2nd edition)

The presented clinical practice guidelines of the Gastroenterological Scientific Society of Russia (GSSR), diagnostic, and therapeutic approaches for patients with digestive diseases during the COVID-19 pandemic. The guidelines were approved by the XXIII Congress of the GSSR and the 22nd International Slavonic-Baltic Scientifi c Forum “St. Petersburg - Gastro-2020 ON-LINE” (St. Petersburg, June 11, 2020). The presented clinical practice guidelines of the Russian Scientific Medical Society of Internal Medicine (RSMSIM) and the Gastroenterological Scientific Society of Russia (GSSR), diagnostic, and therapeutic approaches for patients with digestive diseases during the COVID-19 pandemic. The recommendations were approved at the XV National Congress of Internal Medicine, XXIII Congress of NOGR on the basis of the 1st edition, adopted at the 22nd International Slavic- Baltic Scientific Forum “St. Petersburg - Gastro-2020 ON-LINE”.

Therapeutic approaches to coronavirus infection according to "One Health" concept

Coronaviridae constantly infect human and animals causing respiratory, gastroenteric or systemic diseases. Over time, these viruses have shown a marked ability to mutate, jumping over the human-animal barrier, thus becoming from enzootic to zoonotic. In the last years, numerous therapeutic protocols have been developed, mainly for severe acute respiratory syndromes in humans. The aim of this review is to summarize drugs or other approaches used in coronavirus infections focusing on different roles of these molecules or bacterial products on viral adhesion and replication or in modulating the host's immune system. Within the "One Health" concept, the study of viral pathogenic role and possible therapeutic approaches in both humans and animals is essential to protect public health.

The Role of Microbiome and Virome in Idiopathic Pulmonary Fibrosis

The interest in the lung microbiome and virome and their contribution to the pathogenesis, perpetuation and progression of idiopathic pulmonary fibrosis (IPF) has been increasing during the last decade. The utilization of high-throughput sequencing to detect microbial and/or viral genetic material in bronchoalveolar lavage fluid or lung tissue samples has amplified the ability to identify and quantify specific microbial and viral populations. In stable IPF, higher microbial burden is associated with worse prognosis but no specific microbe has been identified to contribute to this. Additionally, no causative relation has been established. Regarding viral infections, although in the past they have been associated with IPF, causation has not been proved. Although in the past the diagnosis of acute exacerbation of IPF (AE-IPF) was not considered in patients with overt infection, this was amended in the last few years and infection is considered a cause for exacerbation. Besides this, a higher microbial burden has been found in the lungs of patients with AE-IPF and an association with higher morbidity and mortality has been confirmed. In contrast, an association of AE-IPF with viral infection has not been established. Despite the progress during the last decade, a comprehensive knowledge of the microbiome and virome in IPF and their role in disease pathogenesis are yet elusive. Although association with disease severity, risk for progression and mortality has been established, causation has not been proven and the potential use as a biomarker or the benefits of antimicrobial therapeutic strategies are yet to be determined.

The role of nutrition in asthma prevention and treatment

Asthma is a chronic respiratory condition characterized by airway inflammation and hyperreactivity. Prevalence has continued to rise in recent decades as Western dietary patterns have become more pervasive. Evidence suggests that diets emphasizing the consumption of plant-based foods might protect against asthma development and improve asthma symptoms through their effects on systemic inflammation, oxidation, and microbial composition. Additionally, increased fruit and vegetable intake, reduced animal product consumption, and weight management might mediate cytokine release, free radical damage, and immune responses involved in the development and course of asthma. The specific aim of this review paper is to examine the current literature on the associations between dietary factors and asthma risk and control in children and adults. Clinical trials examining the mechanism(s) by which dietary factors influence asthma outcomes are necessary to identify the potential use of nutritional therapy in the prevention and management of asthma.

Microbial community structure and composition is associated with host species and sex in Sigmodon cotton rats

BACKGROUND

The cotton rat (genus Sigmodon) is an essential small animal model for the study of human infectious disease and viral therapeutic development. However, the impact of the host microbiome on infection outcomes has not been explored in this model, partly due to the lack of a comprehensive characterization of microbial communities across different cotton rat species. Understanding the dynamics of their microbiome could significantly help to better understand its role when modeling viral infections in this animal model.

RESULTS

We examined the bacterial communities of the gut and three external sites (skin, ear, and nose) of two inbred species of cotton rats commonly used in research (S. hispidus and S. fulviventer) by using 16S rRNA gene sequencing, constituting the first comprehensive characterization of the cotton rat microbiome. We showed that S. fulviventer maintained higher alpha diversity and richness than S. hispidus at external sites (skin, ear, nose), but there were no differentially abundant genera. However, S. fulviventer and S. hispidus had distinct fecal microbiomes composed of several significantly differentially abundant genera. Whole metagenomic shotgun sequencing of fecal samples identified species-level differences between S. hispidus and S. fulviventer, as well as different metabolic pathway functions as a result of differential host microbiome contributions. Furthermore, the microbiome composition of the external sites showed significant sex-based differences while fecal communities were not largely different.

CONCLUSIONS

Our study shows that host genetic background potentially exerts homeostatic pressures, resulting in distinct microbiomes for two different inbred cotton rat species. Because of the numerous studies that have uncovered strong relationships between host microbiome, viral infection outcomes, and immune responses, our findings represent a strong contribution for understanding the impact of different microbial communities on viral pathogenesis. Furthermore, we provide novel cotton rat microbiome data as a springboard to uncover the full therapeutic potential of the microbiome against viral infections.

Insights into gut microbiome and its functional pathways in asthma patients through high-throughput sequencing

Aim: To describe gut microbiome and functional genes of asthma. Patients & methods: Fecal microbiome in controls, asthma patients with and without inhaled corticosteroid (ICS) treatment was determined. Results: Patients with ICS had lower abundance of Alloprevotella, unclassified_f_Lachnospiraceae and Lachnospiraceae_NC2004_group, higher abundance of Sutterella and Sphingomonas than patients without ICS. In all the asthma patients, there are microbial differences in aging distribution, different gender and different asthmatic phenotypes. Asthma patients without ICS treatment had more microbial genes related to geraniol degradation, ethylbenzene degradation and bladder cancer than controls; 15 pathways showed significant difference between asthma patients with and without ICS treatment. Conclusion: We found gut dysbiosis in asthma and different functional pathways associated with both asthma and ICS.

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.

Gut Dysbiosis during Influenza Contributes to Pulmonary Pneumococcal Superinfection through Altered Short-Chain Fatty Acid Production

Secondary bacterial infections often complicate viral respiratory infections. We hypothesize that perturbation of the gut microbiota during influenza A virus (IAV) infection might favor respiratory bacterial superinfection. Sublethal infection with influenza transiently alters the composition and fermentative activity of the gut microbiota in mice. These changes are attributed in part to reduced food consumption. Fecal transfer experiments demonstrate that the IAV-conditioned microbiota compromises lung defenses against pneumococcal infection. In mechanistic terms, reduced production of the predominant short-chain fatty acid (SCFA) acetate affects the bactericidal activity of alveolar macrophages. Following treatment with acetate, mice colonized with the IAV-conditioned microbiota display reduced bacterial loads. In the context of influenza infection, acetate supplementation reduces, in a free fatty acid receptor 2 (FFAR2)-dependent manner, local and systemic bacterial loads. This translates into reduced lung pathology and improved survival rates of double-infected mice. Lastly, pharmacological activation of the SCFA receptor FFAR2 during influenza reduces bacterial superinfection.

Targeting Microbiome: An Alternative Strategy for Fighting SARS-CoV-2 Infection

Respiratory and gastrointestinal symptoms are the predominant clinical manifestations of the coronavirus disease 2019 (COVID-19). Infecting intestinal epithelial cells, the severe acute respiratory syndrome coronavirus-2 may impact on host's microbiota and gut inflammation. It is well established that an imbalanced intestinal microbiome can affect pulmonary function, modulating the host immune response ("gut-lung axis"). While effective vaccines and targeted drugs are being tested, alternative pathophysiology-based options to prevent and treat COVID-19 infection must be considered on top of the limited evidence-based therapy currently available. Addressing intestinal dysbiosis with a probiotic supplement may, therefore, be a sensible option to be evaluated, in addition to current best available medical treatments. Herein, we summed up pathophysiologic assumptions and current evidence regarding bacteriotherapy administration in preventing and treating COVID-19 pneumonia.

Dietary Patterns, Asthma, and Lung Function in the Hispanic Community Health Study/Study of Latinos

Rationale: Dietary patterns may alter immune responses and increase asthma risk or affect lung function.Objectives: To examine whether a proinflammatory diet (assessed by the energy-adjusted Dietary Inflammatory Index [E-DII]) or high dietary quality (assessed by the Alternative Healthy Eating Index [AHEI-2010]) are associated with current asthma, current asthma symptoms, and lung function in Hispanic adults.Methods: This was a cross-sectional study of 12,687 adults aged 18 to 76 years who participated in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL). The E-DII and AHEI-2010 were calculated based on two 24-hour dietary recalls. Logistic or linear regression was used for the multivariable analysis of E-DII or AHEI-2010 scores and current asthma, asthma symptoms, and lung function measures, adjusting for age, sex, annual household income, study center, Hispanic/Latino background, smoking status, and other covariates.Results: A higher E-DII score was associated with current asthma (odds ratio [OR] for quartile 4 vs. 1, 1.35; 95% confidence interval [CI], 0.97-1.90) and asthma symptoms (OR for quartile 4 vs. 1, 1.42; 95% CI, 1.12-1.81). The AHEI-2010 score was not associated with current asthma or asthma symptoms. Among adults without asthma, a higher E-DII score was associated with lower forced expiratory volume in 1 second (FEV₁) and forced vital capacity (FVC), and a higher AHEI-2010 score was associated with higher FEV₁ and FVC.Conclusions: Our findings suggest that a proinflammatory diet increases the risk of asthma and asthma symptoms in Hispanic adults. An antiinflammatory diet (indicated by a lower E-DII or a higher AHEI-2010 score) may positively influence lung function in Hispanic adults without asthma.

Unraveling the Interconnection Patterns Across Lung Microbiome, Respiratory Diseases, and COVID-19

Albeit the lungs were thought to be sterile, recent scientific data reported a microbial microbiota in the lungs of healthy individuals. Apparently, new developments in technological approachesincluding genome sequencing methodologies contributed in the identification of the microbiota and shed light on the role of the gut and lung microbiomes in the development of respiratory diseases. Moreover, knowledge of the human microbiome in health may act as a tool for evaluating characteristic shifts in the case of disease. This review paper discusses the development of respiratory disease linked to the intestinal dysbiosis which influences the lung immunity and microbiome. The gastrointestinal-lung dialogue provides interesting aspects in the pathogenesis of the respiratory diseases. Lastly, we were further interested on the role of this interconnection in the progression and physiopathology of newly emergedCOVID-19.

Do probiotics help prevent ventilator-associated pneumonia in critically ill patients? A systematic review with meta-analysis

BACKGROUND

Probiotic treatments might contribute to the prevention of ventilator-associated pneumonia (VAP). Due to its unclear clinical effects, here we intend to assess the preventive effect and safety of probiotics on intensive care unit (ICU) patients.

METHODS

Eligible randomised controlled trials were selected in databases until 30 September 2019. The characteristics of the studies were extracted, including study design, definition of VAP, probiotics intervention, category of included patients, incidence of VAP, mortality, duration of mechanical ventilation (MV) and ICU stay. Heterogeneity was evaluated by Chi-squared and I2 tests.

RESULTS

15 studies involving 2039 patients were identified for analysis. The pooled analysis suggests significant reduction on VAP (risk ratio, 0.68; 95% Cl, 0.60 to 0.77; p<0.00001) in a fixed-effects model. Subgroup analyses performed on the category of clinical and microbiological criteria both support the above conclusion; however, there were no significant differences in duration of MV or length of ICU stay in a random-effects model. Also, no significant differences in total mortality, overall mortality, 28-day mortality or 90-day mortality were found in the fixed-effects model.

CONCLUSIONS

The probiotics helped to prevent VAP without impacting the duration of MV, length of ICU stay or mortality.

The Role of Mucosal Immunity and Recombinant Probiotics in SARS-CoV2 Vaccine Development

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), causing the 2019 novel coronavirus disease (COVID-19), was introduced by WHO (World Health Organization) as "pandemic" in March 2020. According to WHO, thus far (23 November 2020) 58,425,681 infected cases including 1,385,218 deaths have been reported worldwide. In order to reduce transmission and spread of this lethal virus, attempts are globally being made to develop an appropriate vaccine. Intending to neutralize pathogens at their initial entrance site, protective mucosal immunity is inevitably required. In SARS-CoV2 infection and transmission, respiratory mucosa plays a key role; hence, apparently mucosal vaccination could be a superior approach to elicit mucosal and systemic immune responses simultaneously. In this review, the advantages of mucosal vaccination to control COVID-19 infection, limitations, and outcomes of mucosal vaccines have been highlighted. Considering the gut microbiota dysregulation in COVID-19, we further provide evidences on utilization of recombinant probiotics, particularly lactic acid bacteria (LAB) as vaccine carrier. Their intrinsic immunomodulatory features, natural adjuvanticity, and feasible expression of relevant antigen in the mucosal surface make them more appealing as live cell factory. Among all available platforms, bioengineered probiotics are considered as the most affordable, most practical, and safest vaccination approach to halt this emerging virus.

The lung-gut axis during viral respiratory infections: the impact of gut dysbiosis on secondary disease outcomes

Bacteria that colonize the human gastrointestinal tract are essential for good health. The gut microbiota has a critical role in pulmonary immunity and host's defense against viral respiratory infections. The gut microbiota's composition and function can be profoundly affected in many disease settings, including acute infections, and these changes can aggravate the severity of the disease. Here, we discuss mechanisms by which the gut microbiota arms the lung to control viral respiratory infections. We summarize the impact of viral respiratory infections on the gut microbiota and discuss the potential mechanisms leading to alterations of gut microbiota's composition and functions. We also discuss the effects of gut microbial imbalance on disease outcomes, including gastrointestinal disorders and secondary bacterial infections. Lastly, we discuss the potential role of the lung-gut axis in coronavirus disease 2019.