The role of microbiota in respiratory health and diseases, particularly in tuberculosis

Assessment of lower respiratory tract microbiota associated with pulmonary tuberculosis in children

BACKGROUND

The respiratory microbiota plays a crucial role in the development of tuberculosis (TB). While existing research has underscored imbalances in the respiratory microbiota of adult patients with TB, information regarding the lower respiratory tract (LRT) microbiota in pediatric patients with TB remains scarce.

METHODS

We employed 16S rRNA gene sequencing technology to investigate the LRT microbial communities of 85 children of different ages with active TB of different severities, 33 children with infectious diseases other than TB, and 48 sex- and age-matched healthy children.

RESULTS

A marked imbalance in the respiratory microbiota was observed in children with TB, highlighted by reduced alpha diversity and a distinct microbial community structure. Comparative analysis indicated that patients with severe TB exhibited lower Neisseria levels than those with non-severe TB (1.01% vs. 3.93%, respectively; p = .02). Streptococcus and Gemella levels were lower in bacteriologically confirmed TB cases compared with clinically diagnosed cases, and higher in healthy children younger than 10 years old than in the older group. Spearman correlation analysis demonstrated significant associations between the microbiota of the LRT and cytokine concentrations in the sputum of children with TB (e.g., an inverse correlation between Veillonella and interleukin-17A).

CONCLUSIONS

TB induced significant dysbiosis in the LRT microbiota of children that was associated with disease severity and the immunological response in the respiratory tract. Our findings may offer a deeper understanding of the role of the respiratory microbiome in TB pathogenesis and progression.

Clinical relevance of lung microbiota composition in critically ill children with acute lower respiratory tract infections: insights from a retrospective analysis of metagenomic sequencing

PURPOSE

Acute lower respiratory tract infections (ALRIs) is a leading cause of child mortality worldwide. Metagenomic next-generation sequencing (mNGS) identifies ALRIs pathogens and explores the lung microbiota's role in disease severity and clinical outcomes. This study examines the association between lung microbiota and ALRIs outcomes in children, exploring its potential as a prognostic biomarker.

METHODS

We retrospectively analyzed mNGS data from the bronchoalveolar lavage fluid (BALF) of 83 pediatric ALRIs patients from 2019 to 2023. Microbial diversity and relative abundances of specific taxa were compared between survivor and non-survivor groups, as well as between varying severity levels. LEfSe was employed to identify key biomarkers related to survival and disease severity.

RESULTS

Among the 83 patients, 68 survived and 15 died. Patients were also divided into a low severity group (n = 38) and a moderate-to-very-high severity group (n = 45) according to mPIRO score at admission. Significant differences in beta diversity were observed between the survival groups and across different severity levels. Prevotella, Haemophilus and Veillonella exhibited higher abundances in both the survivor and low severity groups, suggesting their potential as predictors of better outcomes. Conversely, Enterococcus and Acinetobacter baumannii were more prevalent in the non-survivor and moderate-to-very-high severity groups. Additionally, Streptococcus pneumoniae and Streptococcus mitis showed increased abundances in survivors. LEfSe further revealed that these microorganisms may predict outcomes and severity in ALRIs.

CONCLUSION

Our findings underscore the complex relationship between lung microbiota and ALRIs, with specific microbial profiles associated with disease severity and clinical outcomes. This underscores the need for further research to explore and validate its prognostic predictive capacity.

CLINICAL TRIAL NUMBER

Not applicable.

The impact of anti-tuberculosis treatment on respiratory tract microbiome in pulmonary tuberculosis

The growing evidence has underscored the significance of interactions between the host and microbiota in respiratory health, presenting a novel perspective on disease management. Yet, comprehension of the respiratory microbiome shifts before and after anti-tuberculosis treatment is limited. This study compares respiratory microbiome profiles in untreated tuberculosis (UTB) and completed TB treatment (CTB) cases with healthy controls, using 16S rRNA sequencing on sputum samples. Significant reduction in sputum microbial alpha diversity was observed in both TB groups when compared to healthy controls (P < 0.05). Beta diversity analysis showed distinct clustering (P < 0.05). Linear discriminant analysis revealed an abundance of potentially pathogenic bacterial genera like Haemophilus, Pseudomonas, and Mycobacterium in the UTB group, while Streptococcus, Rothia, and Neisseria dominated in CTB samples. Healthy sputum microbiomes were enriched with Prevotella, Fusobacterium, Porphyromonadaceae_unclassified,andPeptostreptococcus. Moreover, predicted bacterial functional pathways showed significant differences among the three groups, mainly related to nutrient metabolism. These findings indicated significant microbial dysbiosis in sputum samples recovered from patients with pulmonary TB with an elevated presence of potentially pathogenic bacteria, depletion of beneficial genera, and downregulation of several essential metabolic pathways. Further exploration of respiratory microbiome-based diagnostic biomarkers and their role in targeted treatment strategies in tuberculosis is warranted.

Exploring the potential role of microbiota and metabolites in acute exacerbation of chronic obstructive pulmonary disease

The acute exacerbation of chronic obstructive pulmonary disease seriously affects the respiratory system function and quality of life of patients. This study employed 16S rRNA sequencing and metabolomics techniques to analyze the respiratory microbiota and serum metabolites of COPD and AECOPD patients. The results showed that the microbial diversity in the respiratory tract of AECOPD patients was significantly lower than that of COPD patients, and the relative abundance of Bacteroidetes, Prevotella and Neisseria in the respiratory tract of AECOPD patients was significantly lower than that of COPD patients. However, the relative abundance of Haemophilus_D, Veillonella_A and Pseudomonas_E, in AECOPD patients was significantly higher than that of COPD patients, and the ability of respiratory microbiota in AECOPD patients to participate in alanine metabolism was significantly lower than that of COPD patients. Metabolome results further revealed that the serum alanine levels in AECOPD patients were significantly lower than those in COPD patients, and these differential metabolites were mainly involved in linoleic acid metabolism, protein digestion and absorption and regulation of lipolysis in adipocytes. In summary, the structural characteristics of respiratory microbiota in COPD and AECOPD patients are different from those in healthy populations, and their microbiota diversity decreases and microbial community structure and function will also undergo changes when acute exacerbations occur. In addition, the predicted microbial community function and metabolomics results indicate that the onset of AECOPD is mainly related to energy and amino acid metabolism disorders, especially alanine metabolism.

Air pollution, dysbiosis and diseases: pneumonia, asthma, COPD, lung cancer and irritable bowel syndrome

With substantial effects on human health, air pollution has become a major global concern. Air pollution has been linked to numerous gastrointestinal and respiratory diseases with increasing mortalities. The gut and respiratory dysbiosis brought about by air pollution has recently received much attention. This review attempts to provide an overview of the types of air pollutants, their sources, their impact on the respiratory and gut dysbiotic patterns and their correlation with five major diseases including pneumonia, asthma, COPD, lung cancer and irritable bowel syndrome. Deeper insights into the links between pollutants, dysbiosis and disease may pave the way for novel diagnostic biomarkers for prognosis and early detection of these diseases, as well as ways to ease the disease burden.

Crosstalk between ROS-inflammatory gene expression axis in the progression of lung disorders

A significant number of deaths and disabilities worldwide are brought on by inflammatory lung diseases. Many inflammatory lung disorders, including chronic respiratory emphysema, resistant asthma, resistance to steroids, and coronavirus-infected lung infections, have severe variants for which there are no viable treatments; as a result, new treatment alternatives are needed. Here, we emphasize how oxidative imbalance contributes to the emergence of provocative lung problems that are challenging to treat. Endogenic antioxidant systems are not enough to avert free radical-mediated damage due to the induced overproduction of ROS. Pro-inflammatory mediators are then produced due to intracellular signaling events, which can harm the tissue and worsen the inflammatory response. Overproduction of ROS causes oxidative stress, which causes lung damage and various disease conditions. Invasive microorganisms or hazardous substances that are inhaled repeatedly can cause an excessive amount of ROS to be produced. By starting signal transduction pathways, increased ROS generation during inflammation may cause recurrent DNA damage and apoptosis and activate proto-oncogenes. This review provides information about new targets for conducting research in related domains or target factors to prevent, control, or treat such inflammatory oxidative stress-induced inflammatory lung disorders.

Clinical and microbiological characteristics of a hospital outbreak of Candida auris in a referral hospital in Lima, Peru

BACKGROUND

Candida auris, a multidrug-resistant fungal pathogen, has received considerable attention owing to its recent surge, especially in South America, which coincides with the ongoing global COVID-19 pandemic. Understanding the clinical and microbiological characteristics of outbreaks is crucial for their effective management and control.

OBJECTIVE

This retrospective observational study aimed to characterize a C. auris outbreak at a Peruvian referral hospital between January 2021 and July 2023.

METHODS

Data were collected from hospitalized patients with positive C. auris culture results. Microbiological data and antifungal susceptibility test results were analysed. Additionally, infection prevention and control measures have been described. Statistical analysis was used to compare the characteristics between the infected and colonized patients.

RESULTS

Thirty-three patients were identified, mostly male (66.7%), with a median age of 53 years. Among them, 18 (54.5%) were colonized, and 15 (45.5%) were infected. Fungemia was the predominant presentation (80%), with notable cases of fungemia in tuberculosis patients with long-stay devices for parenteral anti-tuberculosis therapy. Seventy-five percent of the isolates exhibited fluconazole resistance. Echinocandins were the primary treatment, preventing fungemia recurrence within 30 days. Infected patients had significantly longer hospital stays than colonized patients (100 vs. 45 days; p = .023). Hospital mortality rates were 46.7% and 25% in the infected and fungemia patients, respectively. Simultaneous outbreaks of multidrug-resistant bacteria were documented.

CONCLUSIONS

This study underscores the severity of a C. auris outbreak at a referral hospital in Peru, highlighting its significant impact on patient outcomes and healthcare resources. The high prevalence of fluconazole-resistant isolates, leading to prolonged hospital stay and high mortality rates, particularly in cases of fungemia, underscores the critical need for effective infection prevention and control strategies.

Effect and mechanism of quercetin or quercetin-containing formulas against COVID-19: From bench to bedside

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the global coronavirus disease 2019 (COVID-19) pandemic since 2019. Immunopathogenesis and thromboembolic events are central to its pathogenesis. Quercetin exhibits several beneficial activities against COVID-19, including antiviral, anti-inflammatory, immunomodulatory, antioxidative, and antithrombotic effects. Although several reviews have been published, these reviews are incomplete from the viewpoint of translational medicine. The authors comprehensively evaluated the evidence of quercetin against COVID-19, both basically and clinically, to apply quercetin and/or its derivatives in the future. The authors searched the PubMed, Embase, and the Cochrane Library databases without any restrictions. The search terms included COVID-19, SARS-CoV-2, quercetin, antiviral, anti-inflammatory, immunomodulatory, thrombosis, embolism, oxidative, and microbiota. The references of relevant articles were also reviewed. All authors independently screened and reviewed the quality of each included manuscript. The Cochrane Risk of Bias Tool, version 2 (RoB 2) was used to assess the quality of the included randomized controlled trials (RCTs). All selected studies were discussed monthly. The effectiveness of quercetin against COVID-19 is not solid due to methodological flaws in the clinical trials. High-quality studies are also required for quercetin-containing traditional Chinese medicines. The low bioavailability and highly variable pharmacokinetics of quercetin hinder its clinical applications. Its positive impact on immunomodulation through reverting dysbiosis of gut microbiota still lacks robust evidence. Quercetin against COVID-19 does not have tough clinical evidence. Strategies to improve its bioavailability and/or to develop its effective derivatives are needed. Well-designed RCTs are also crucial to confirm their effectiveness in the future.

Correlation between intestinal flora and GLP-1 receptor agonist dulaglutide in type 2 diabetes mellitus treatment-A preliminary longitudinal study

GLP-1 receptor agonists (GLP-1 RA) are presently used as the first-line drugs for the clinical treatment of type 2 diabetes mellitus (T2DM). It can regulate blood glucose by stimulating insulin secretion and lowering glucagon levels. We used 16S rRNA amplicon sequencing to detect structural changes in the composition of the intestinal flora of newly diagnosed T2DM after 1 and 48 weeks of dulaglutide administration. Our research found no significant changes in the intestinal flora after the administration of dulaglutide for 1 week to subjects with newly diagnosed T2DM. Nevertheless, after 48 weeks of dulaglutide administration, the composition of the intestinal flora changed significantly, with a significant reduction in the abundance of intestinal flora. Furthermore, we found that fasting glucose levels, fasting c-peptide levels, HbA1c levels, and BMI are also closely associated with intestinal flora. This reveals that intestinal flora may be one of the mechanisms by which dulaglutide treats T2DM.

Detection of non-tuberculous mycobacteria in native wildlife species at conservation risk of Argentina

Introduction

Non-tuberculous Mycobacteria (NTM) are mainly environmental but can cause opportunistic infections and diseases in humans and animals. Livestock and wild animals can be infected with NTM. In Argentina, there are native wild species facing conservation risks, and they are the focus of protection and reintroduction projects designed to preserve biodiversity in various ecoregions. The aim of this study was to report the presence of NTM in samples collected from four endangered native wild species from nine Argentine provinces, as part of their pre-release health assessment.

Methods

A total of 165 samples from giant anteater, peccary, tapir and pampas deer were obtained, these included either bronchoalveolar or endotracheal lavages, or oropharyngeal, nasopharyngeal or tracheal swabs. Bacteriological culture followed by molecular identification and sequencing were performed.

Results

A total of 27 NTM were detected, including Mycobacterium avium subsp. hominissuis, M. intracellulare, M. terrae, M. gordonense, M. kumamotonense, M. fortuitum, M. saskatchewanense, and M. genavense. Results revealed a 16,36% NTM recovery rate, with the giant anteater showing the highest prevalence among the mammals under study.

Discussion

In Argentina, due to extensive production systems, the interaction between domestic and wild species sharing the same environment is frequent, increasing the exposure of all the species to these NTM. In this way, the transmission of infectious agents from one to another is feasible. Moreover, NTMs might interfere with the diagnosis of bovine tuberculosis and paratuberculosis. These findings emphasize the importance of active health surveillance in conservation programs. It highlights the need to address NTM epidemiology in wildlife and its impact on conservation and public health.

The Interplay between Mycobacterium tuberculosis and Human Microbiome

Tuberculosis (TB), a respiratory disease caused by Mycobacterium tuberculosis (Mtb), is a significant cause of mortality worldwide. The lung, a breeding ground for Mtb, was once thought to be a sterile environment, but has now been found to host its own profile of microbes. These microbes are critical in the development of the host immune system and can produce metabolites that aid in host defense against various pathogens. Mtb infection as well as antibiotics can shift the microbial profile, causing dysbiosis and dampening the host immune response. Additionally, increasing cases of drug resistant TB have impacted the success rates of the traditional therapies of isoniazid, rifampin, pyrazinamide, and ethambutol. Recent years have produced tremendous research into the human microbiome and its role in contributing to or attenuating disease processes. Potential treatments aimed at altering the gut-lung bacterial axis may offer promising results against drug resistant TB and help mitigate the effects of TB.

The uncharted territory of host-pathogen interaction in tuberculosis

Mycobacterium tuberculosis (M.tb) effectively manipulates the host processes to establish the deadly respiratory disease, Tuberculosis (TB). M.tb has developed key mechanisms to disrupt the host cell health to combat immune responses and replicate efficaciously. M.tb antigens such as ESAT-6, 19kDa lipoprotein, Hip1, and Hsp70 destroy the integrity of cell organelles (Mitochondria, Endoplasmic Reticulum, Nucleus, Phagosomes) or delay innate/adaptive cell responses. This is followed by the induction of cellular stress responses in the host. Such cells can either undergo various cell death processes such as apoptosis or necrosis, or mount effective immune responses to clear the invading pathogen. Further, to combat the infection progression, the host secretes extracellular vesicles such as exosomes to initiate immune signaling. The exosomes can contain M.tb as well as host cell-derived peptides that can act as a double-edged sword in the immune signaling event. The host-symbiont microbiota produces various metabolites that are beneficial for maintaining healthy tissue microenvironment. In juxtaposition to the above-mentioned mechanisms, M.tb dysregulates the gut and respiratory microbiome to support its replication and dissemination process. The above-mentioned interconnected host cellular processes of Immunometabolism, Cellular stress, Host Microbiome, and Extracellular vesicles are less explored in the realm of exploration of novel Host-directed therapies for TB. Therefore, this review highlights the intertwined host cellular processes to control M.tb survival and showcases the important factors that can be targeted for designing efficacious therapy.

Microbiome Alteration in Lung Tissues of Tuberculosis Patients Revealed by Metagenomic Next-Generation Sequencing and Immune-Related Transcriptional Profile Identified by Transcriptome Sequencing

This study explored alterations in the respiratory microbiome and transcriptome after Mycobacterium tuberculosis infection in tuberculosis (TB) patients. Metagenomic next-generation sequencing (mNGS) was adopted to reveal the microbiome in lung tissues from 110 TB and 25 nontuberculous (NonTB) patients. Transcriptome sequencing was performed in TB tissues (n = 3), tissues adjacent to TB (ParaTB, n = 3), and NonTB tissues (n = 3) to analyze differentially expressed genes (DEGs) and functional pathways. The microbial β diversity (p = 0.01325) in TB patients differed from that in the NonTB group, with 17 microbial species distinctively distributed. Eighty-three co-up-regulated DEGs were identified in the TB versus NonTB and the TB versus ParaTB comparison groups, and six were associated with immune response to Mtb. These DEGs were significantly enriched in the signaling pathways such as immune response, NF-κB, and B cell receptor. Data in the lung tissue microbiome and transcriptome in TB patients offer a sufficient understanding of the pathogenesis of TB.

Helper T cell bias following tuberculosis chemotherapy identifies opportunities for therapeutic vaccination to prevent relapse

Therapeutic vaccines have promise as adjunctive treatment for tuberculosis (TB) or as preventives against TB relapse. An important development challenge is the limited understanding of T helper (Th) cell roles during these stages of disease. A murine model of TB relapse was used to identify changes in Th populations and cytokine microenvironment. Active TB promoted expansion of Th1, Th2, Th17, and Th22 cells and cytokines in the lung. Following drug therapy, pulmonary Th17 and Th22 cells contracted, Th1 cells remained elevated, while Th cells producing IL-4 or IL-10 expanded. At relapse, Th22 cells failed to re-expand in the lung despite a moderate re-expansion of Th1 and Th17 cells and an increase in Th cytokine polyfunctionality. The dynamics of Th populations further differed by tissue compartment and disease presentation. These outcomes identify immune bias by Th subpopulations during TB relapse as candidate mechanisms for pathogenesis and targets for therapeutic vaccination.

Gut Microbiota and Respiratory Infections: Insights from Mendelian Randomization

The role of the gut microbiota in modulating the risk of respiratory infections has garnered increasing attention. However, conventional clinical trials have faced challenges in establishing the precise relationship between the two. In this study, we conducted a Mendelian randomization analysis with single nucleotide polymorphisms employed as instrumental variables to assess the causal links between the gut microbiota and respiratory infections. Two categories of bacteria, family Lactobacillaceae and genus Family XIII AD3011, were causally associated with the occurrence of upper respiratory tract infections (URTIs). Four categories of gut microbiota existed that were causally associated with lower respiratory tract infections (LRTIs), with order Bacillales and genus Paraprevotella showing a positive association and genus Alistipes and genus Ruminococcaceae UCG009 showing a negative association. The metabolites and metabolic pathways only played a role in the development of LRTIs, with the metabolite deoxycholine acting negatively and menaquinol 8 biosynthesis acting positively. The identification of specific bacterial populations, metabolites, and pathways may provide new clues for mechanism research concerning therapeutic interventions for respiratory infections. Future research should focus on elucidating the potential mechanisms regulating the gut microbiota and developing effective strategies to reduce the incidence of respiratory infections. These findings have the potential to significantly improve global respiratory health.

Impact of the gut-lung axis on tuberculosis susceptibility and progression

Tuberculosis (TB) has remained at the forefront of the global infectious disease burden for centuries. Concerted global efforts to eliminate TB have been hindered by the complexity of Mycobacterium tuberculosis (Mtb), the emergence of antibiotic resistant Mtb strains and the recent impact of the ongoing pandemic of coronavirus disease 2019 (COVID19). Examination of the immunomodulatory role of gastrointestinal microbiota presents a new direction for TB research. The gut microbiome is well-established as a critical modulator of early immune development and inflammatory responses in humans. Recent studies in animal models have further substantiated the existence of the 'gut-lung axis', where distal gastrointestinal commensals modulate lung immune function. This gut microbiome-lung immune crosstalk is postulated to have an important correlation with the pathophysiology of TB. Further evaluation of this gut immunomodulation in TB may provide a novel avenue for the exploration of therapeutic targets. This mini-review assesses the proposed mechanisms by which the gut-lung axis impacts TB susceptibility and progression. It also examines the impact of current anti-TB therapy on the gut microbiome and the effects of gut dysbiosis on treatment outcomes. Finally, it investigates new therapeutic targets, particularly the use of probiotics in treatment of antibiotic resistant TB and informs future developments in the field.

The gut and lung microbiota in pulmonary tuberculosis: susceptibility, function, and new insights into treatment

INTRODUCTION

Tuberculosis (TB) is a chronic infectious disease caused by mycobacterium tuberculosis (Mtb) that poses a major threat to human health.

AREAS COVERED

Herein, we aim to review the alteration of the microbiota in gut and respiratory during TB development, the potential function and mechanisms of microbiota in the pathogenesis of Mtb infection, and the impact of antibiotic treatment on the microbiota. In addition, we discuss the potential new paradigm for the use of microbiota-based treatments such as probiotics and prebiotics in the treatment of TB.

EXPERT OPINION

Studies have shown that trillions of micro-organisms live in the human gut and respiratory tract, acting as gatekeepers in maintaining immune homeostasis and respiratory physiology and playing a beneficial or hostile role in the development of TB. Anti-TB antibiotics may cause microecological imbalances in the gut and respiratory tract, and microbiome-based therapeutics may be a promising strategy for TB treatment. Appropriate probiotics and prebiotics supplementation, along with antimycobacterial treatment, will improve the therapeutic effect of TB treatment and protect the gut and respiratory microbiota from dysbiosis.

The Enterococcus secretome inhibits the growth of Mycobacterium tuberculosis complex mycobacteria

Enterococcus mundtii , a commensal intestinal bacterium, was demonstrated to inhibit the growth of some Mycobacterium tuberculosis complex (MTC) species that cause tuberculosis in humans and mammals. To further explore this preliminary observation, we cross-investigated five E. mundtii strains and seven MTC strains representative of four MTC species using a standardized quantitative agar well diffusion assay. All five E. mundtii strains, calibrated at 10 MacFarland, inhibited the growth of all M. tuberculosis strains with various susceptibility profiles, but no inhibition was observed with lower inoculums. Further, eight E. mundtii freeze-dried cell-free culture supernatants (CFCS) inhibited the growth of M. tuberculosis , Mycobacterium africanum, Mycobacterium bovis and Mycobacterium canettii, the most susceptible MTC species (inhibition diameter 25±1 mm), proportionally to CFCS protein concentrations. The data reported here indicate that the E. mundtii secretome inhibited growth of all MTC species of medical interest, which broadens previously reported data. In the gut, the E. mundtii secretome may modulate the expression of tuberculosis, exhibiting an anti-tuberculosis effect, with some protective roles in human and animal health.

Baicalin ameliorates multidrug-resistant Pseudomonas aeruginosa induced pulmonary inflammation in rat via arginine biosynthesis

Multidrug-resistance (MDR) Pseudomonas aeruginosa (P. aeruginosa) is a lethal gram-negative pathogen causing hospital-acquired and ventilator-associated pneumonia, which is difficult to treat. Our previous studies confirmed that baicalin, an essential bioactive component in Scutellaria baicalensis Georgi, exhibited anti-inflammatory effects in an acute pneumonia rat model induced by MDR P. aeruginosa. However, this effect of baicalin in constrast its low bioavailability, and its mechanism of action is still unknown. Thus, this study investigated whether the therapeutic effects of baicalin against MDR P. aeruginosa acute pneumonia are owing to the regulation of gut microbiota and their metabolites using pyrosequencing of the 16S rRNA genes in rat feces and metabolomics. As a result, baicalin attenuated the inflammation by acting directly on neutrophils and regulated the production of the inflammatory cytokines TNF-α, IL-1β, IL-6, and IL-10. The mechanisms were through down-regulation of TLR4 and inhibition of NF-κB. Furthermore, pyrosequencing of the 16S rRNA genes in rat feces revealed that baicalin regulated the composition of gut microbial communities. At the genus level, baicalin efficiently increased the abundance of Ligilactobacillus, Lactobacillus and Bacteroides, but decreased the abundance of Muribaculaceae and Alistipes. Further, arginine biosynthesis was analyzed as the core pathway regulated by baicalin via combination with predicting gut microbiota function and targeted metabolomics. In conclusion, this study has demonstrated that baicalin relieved inflammatory injury in acute pneumonia rat induced by MDR P. aeruginosa via arginine biosynthesis associated with gut microbiota. Baicalin could be a promising and effective adjunctive therapy for lung inflammation caused by MDR P. aeruginosa infection.

Intestinal Damage, Inflammation and Microbiota Alteration during COVID-19 Infection

Background: The virus SARS-CoV-2 is responsible for respiratory disorders due to the fact that it mainly infects the respiratory tract using the Angiotensin-converting enzyme 2 (ACE2) receptors. ACE2 receptors are also highly expressed on intestinal cells, representing an important site of entry for the virus in the gut. Literature studies underlined that the virus infects and replicates in the gut epithelial cells, causing gastrointestinal symptoms such as diarrhea, abdominal pain, nausea/vomiting and anorexia. Moreover, the SARS-CoV-2 virus settles into the bloodstream, hyperactivating the platelets and cytokine storms and causing gut–blood barrier damage with an alteration of the gut microbiota, intestinal cell injury, intestinal vessel thrombosis leading to malabsorption, malnutrition, an increasing disease severity and mortality with short and long-period sequelae. Conclusion: This review summarizes the data on how SARS-CoV-2 effects on the gastrointestinal systems, including the mechanisms of inflammation, relationship with the gut microbiota, endoscopic patterns, and the role of fecal calprotectin, confirming the importance of the digestive system in clinical practice for the diagnosis and follow-up of SARS-CoV-2 infection.

Gastrointestinal microbiota: A predictor of COVID-19 severity?

Coronavirus disease 2019 (COVID-19), caused by a severe acute respiratory syndrome coronavirus 2 infection, has raised serious concerns worldwide over the past 3 years. The severity and clinical course of COVID-19 depends on many factors (e.g., associated comorbidities, age, etc) and may have various clinical and imaging findings, which raises management concerns. Gut microbiota composition is known to influence respiratory disease, and respiratory viral infection can also influence gut microbiota. Gut and lung microbiota and their relationship (gut-lung axis) can act as modulators of inflammation. Modulating the intestinal microbiota, by improving its composition and diversity through nutraceutical agents, can have a positive impact in the prophylaxis/treatment of COVID-19.

The Efficacy of Probiotics as Antiviral Agents for the Treatment of Rotavirus Gastrointestinal Infections in Children: An Updated Overview of Literature

Enteric viruses, including the rotavirus, norovirus, and adenoviruses, are the most common cause of acute gastroenteritis. The rotavirus disease is especially prevalent among children, and studies over the past decade have revealed complex interactions between rotaviruses and the gut microbiota. One way to treat and prevent dysbiosis is the use of probiotics as an antiviral agent. This review focuses on the latest scientific evidence on the antiviral properties of probiotics against rotavirus gastroenteric infections in children. A total of 19 studies exhibited a statistically significant antiviral effect of probiotics. The main probiotics that were effective were Saccharomyces cerevisiae var. boulardii, Lacticaseibacillus rhamnosus GG, and various multi-strain probiotics. The underlying mechanism of the probiotics against rotavirus gastroenteric infections in children included immune enhancement and modulation of intestinal microbiota leading to shortening of diarrhoea. However, several clinical studies also found no significant difference in the probiotic group compared to the placebo group even though well-known strains were used, thus showing the importance of correct dosage, duration of treatment, quality of probiotics and the possible influence of other factors, such as the production process of probiotics and the influence of immunisation on the effect of probiotics. Therefore, more robust, well-designed clinical studies addressing all factors are warranted.

Gut-Lung Microbiota Interaction in COPD Patients: A Literature Review

Respiratory diseases are one of the leading causes of death in the world, which is why a lot of attention has been recently paid to studying the possible mechanisms for the development of pulmonary diseases and assessing the impact on their course. The microbiota plays an important role in these processes and influences the functionality of the human immune system. Thus, alterations in the normal microflora contribute to a reduction in immunity and a more severe course of diseases. In this review, we summarized the information about gut and lung microbiota interactions with particular attention to their influence on the course of chronic obstructive pulmonary disease (COPD).

Antibiotic Resistance to Mycobacterium tuberculosis and Potential Use of Natural and Biological Products as Alternative Anti-Mycobacterial Agents

Background: Tuberculosis (TB) is an infectious disease caused by the bacillus Mycobacterium tuberculosis (Mtb). TB treatment is based on the administration of three major antibiotics: isoniazid, rifampicin, and pyrazinamide. However, multi-drug resistant (MDR) Mtb strains are increasing around the world, thus, allowing TB to spread around the world. The stringent response is demonstrated by Mtb strains in order to survive under hostile circumstances, even including exposure to antibiotics. The stringent response is mediated by alarmones, which regulate bacterial replication, transcription and translation. Moreover, the Mtb cell wall contributes to the mechanism of antibiotic resistance along with efflux pump activation and biofilm formation. Immunity over the course of TB is managed by M1-macrophages and M2-macrophages, which regulate the immune response against Mtb infection, with the former exerting inflammatory reactions and the latter promoting an anti-inflammatory profile. T helper 1 cells via secretion of interferon (IFN)-gamma, play a protective role in the course of TB, while T regulatory cells secreting interleukin 10, are anti-inflammatory. Alternative therapeutic options against TB require further discussion. In view of the increasing number of MDR Mtb strains, attempts to replace antibiotics with natural and biological products have been object of intensive investigation. Therefore, in this review the anti-Mtb effects exerted by probiotics, polyphenols, antimicrobial peptides and IFN-gamma will be discussed. All the above cited compounds are endowed either with direct antibacterial activity or with anti-inflammatory and immunomodulating characteristics.

Pathogenesis of SARS-CoV-2 and Mycobacterium tuberculosis Coinfection

Coronavirus disease-2019 (COVID-19), caused by SARS-CoV-2, is an infectious disease that poses severe threats to global public health and significant economic losses. The COVID-19 global burden is rapidly increasing, with over 246.53 million COVID-19 cases and 49.97 million deaths reported in the WHO 2021 report. People with compromised immunity, such as tuberculosis (TB) patients, are highly exposed to severe COVID-19. Both COVID-19 and TB diseases spread primarily through respiratory droplets from an infected person to a healthy person, which may cause pneumonia and cytokine storms, leading to severe respiratory disorders. The COVID-19-TB coinfection could be fatal, exacerbating the current COVID-19 pandemic apart from cellular immune deficiency, coagulation activation, myocardial infarction, and other organ dysfunction. This study aimed to assess the pathogenesis of SARS-CoV-2-Mycobacterium tuberculosis coinfections. We provide a brief overview of COVID19-TB coinfection and discuss SARS-CoV-2 host cellular receptors and pathogenesis. In addition, we discuss M. tuberculosis host cellular receptors and pathogenesis. Moreover, we highlight the impact of SARS-CoV-2 on TB patients and the pathological pathways that connect SARS-CoV-2 and M. tuberculosis infection. Further, we discuss the impact of BCG vaccination on SARS-CoV-2 cases coinfected with M. tuberculosis, as well as the diagnostic challenges associated with the coinfection.