The Bidirectional Gut-Lung Axis in COPD

Epidemiological studies indicate that chronic obstructive pulmonary disease (COPD) is associated with the incidence of changes in intestinal health. Cigarette smoking, as one of the major causes of COPD, can have an impact on the gastrointestinal system and promotes intestinal diseases. This points to the existence of gut-lung interactions, however, an overview of the underlying mechanisms of the bidirectional connection between the lungs and the gut in COPD is lacking. The interaction between the lungs and the gut can occur through circulating inflammatory cells and mediators. Moreover, gut microbiota dysbiosis, observed in both COPD and intestinal disorders, can lead to a disturbed mucosal environment, including the intestinal barrier and immune system, and hence, may negatively affect both the gut and the lungs. Furthermore, systemic hypoxia and oxidative stress that occurs in COPD may also be involved in intestinal dysfunction and play a role in the gut-lung axis. This review summarizes data from clinical research, animal models and in vitro studies that may explain the possible mechanisms of gut-lung interactions associated with COPD. Interesting observations on the possibility of promising future add-on therapies for intestinal dysfunction in COPD patients will be highlighted.

Resilience and stability of the CF- intestinal and respiratory microbiome during nutritional and exercise intervention

BACKGROUND

Impaired respiratory and intestinal microbiome composition is linked to cystic fibrosis lung disease severity. In people with cystic fibrosis (pwCF), regular exercise is recommended to delay disease progression and preserve a stable lung function. An optimal nutritional status is vital for best clinical outcomes. Our study investigated whether regular and monitored exercise and nutritional support promotes CF microbiome health.

METHODS

A personalized nutrition and exercise program promoted nutritional intake and physical fitness in 18 pwCF for 12 months. Throughout the study, patients performed strength and endurance training monitored by a sports scientist via an internet platform. After three months, food supplementation with Lactobacillus rhamnosus LGG was introduced. Nutritional status and physical fitness were assessed before the study started, after three and nine months. Sputum and stool were collected, and microbial composition was analyzed by 16S rRNA gene sequencing.

RESULTS

Sputum and stool microbiome composition remained stable and highly specific to each patient during the study period. Disease-associated pathogens dominated sputum composition. Lung disease severity and recent antibiotic treatment had the highest impact on taxonomic composition in stool and sputum microbiome. Strikingly, the long-term antibiotic treatment burden had only a minor influence.

CONCLUSION

Despite the exercise and nutritional intervention, respiratory and intestinal microbiomes proved to be resilient. Dominant pathogens drove the composition and functionality of the microbiome. Further studies are required to understand which therapy could destabilize the dominant disease-associated microbial composition of pwCF.

Potential role of the microbiome in liver injury during COVID-19: Further research is needed

Although different studies have associated coronavirus disease 2019 (COVID-19) with the occurrence of liver injury, the hepatic injury route during the COVID-19 course is not yet fully understood. In order to better understand the mechanisms of the disease, the human gut microbiota has been the subject of extensive discussion in the context of COVID-19 pathophysiology. However, many questions remain, including the risks of liver injury due to COVID-19 specific populations. Further research in this field could allow the discovery of new personalized treatment strategies aimed at improving the microbiota composition, thereby reducing COVID-19 severity and its complications in different populations. In this article, we discussed basic mechanisms of severe acute respiratory syndrome coronavirus 2 infection and recent evidence on the relationship between COVID-19, the gut microbiome and liver injury as well as proposed recommendations for further research.

Gastrointestinal consequences of lipopolysaccharide-induced lung inflammation

BACKGROUND

Respiratory inflammation is the body's response to lung infection, trauma or hypersensitivity and is often accompanied by comorbidities, including gastrointestinal (GI) symptoms. Why respiratory inflammation is accompanied by GI dysfunction remains unclear. Here, we investigate the effect of lipopolysaccharide (LPS)-induced lung inflammation on intestinal barrier integrity, tight-junctions, enteric neurons and inflammatory marker expression.

METHODS

Female C57bl/6 mice (6-8 weeks) were intratracheally administered LPS (5 µg) or sterile saline, and assessed after either 24 or 72 h. Total and differential cell counts in bronchoalveolar lavage fluid (BALF) were used to evaluate lung inflammation. Intestinal barrier integrity was assessed via cross sectional immunohistochemistry of tight junction markers claudin-1, claudin-4 and EpCAM. Changes in the enteric nervous system (ENS) and inflammation in the intestine were quantified immunohistochemically using neuronal markers Hu + and nNOS, glial markers GFAP and S100β and pan leukocyte marker CD45.

RESULTS

Intratracheal LPS significantly increased the number of neutrophils in BALF at 24 and 72 h. These changes were associated with an increase in CD45 + cells in the ileal mucosa at 24 and 72 h, increased goblet cell expression at 24 h, and increased expression of EpCAM at 72 h. LPS had no effect on the expression of GFAP, S100β, nor the number of Hu + neurons or proportion of nNOS neurons in the myenteric plexus.

CONCLUSIONS

Intratracheal LPS administration induces inflammation in the ileum that is associated with enhanced expression of EpCAM, decreased claudin-4 expression and increased goblet cell density, these changes may contribute to systemic inflammation that is known to accompany many inflammatory diseases of the lung.

Intermodulation of gut-lung axis microbiome and the implications of biotics to combat COVID-19

The novel coronavirus disease pandemic caused by the COVID-19 virus has infected millions of people around the world with a surge in transmission and mortality rates. Although it is a respiratory viral infection that affects airway epithelial cells, a diverse set of complications, including cytokine storm, gastrointestinal disorders, neurological distress, and hyperactive immune responses have been reported. However, growing evidence indicates that the bidirectional crosstalk of the gut-lung axis can decipher the complexity of the disease. Though not much research has been focused on the gut-lung axis microbiome, there is a translocation of COVID-19 infection from the lung to the gut through the lymphatic system resulting in disruption of gut permeability and its integrity. It is believed that detailed elucidation of the gut-lung axis crosstalk and the role of microbiota can unravel the most significant insights on the discovery of diagnosis using microbiome-based-therapeutics for COVID-19. This review calls attention to relate the influence of dysbiosis caused by COVID-19 and the involvement of the gut-lung axis. It presents first of its kind details that concentrate on the momentousness of biotics in disease progression and restoration. Communicated by Ramaswamy H. Sarma.

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.

Intestinal microbiota metabolizing Houttuynia cordata polysaccharides in H1N1 induced pneumonia mice contributed to Th17/Treg rebalance in gut-lung axis

Influenza A virus is intricately linked to dysregulation of gut microbiota and host immunity. Previous study revealed that Houttuynia cordata polysaccharides (HCP) exert the therapeutic effect on influenza A virus inducing lung and intestine damage via regulating pulmonary and intestinal mucosal immunity. However, whether this result was due to the regulation of gut microbiota in the gut-lung axis remains unclear. Here, we firstly found that the elimination of gut microbiota using antibiotic cocktails led to both loss of the protective effect of HCP on intestine and lung injury, and reduction of the efficacy on regulating Th17/Treg balance in gut-lung axis. Fecal microbiota transplantation study confirmed that the gut microbiota fermented with HCP under pathological conditions (H1N1 infection) was responsible for reducing pulmonary and intestinal injury. Moreover, the interaction of HCP and gut microbiota under pathological conditions exhibited not only much more abundant gut microbial diversity, but also higher content of the acetate. Our results demonstrated that the underlying mechanism to ameliorate viral pneumonia in mice involving Th17/Treg rebalance via the gut microbiota and HCP metabolite (acetate) metabolized in pneumonia mice. Our results provided a new insight for macromolecular polysaccharides through targeting intestinal microenvironment reducing distant pulmonary infection.

Herbal medicine in the treatment of COVID-19 based on the gut-lung axis

Respiratory symptoms are most commonly experienced by patients in the early stages of novel coronavirus disease 2019 (COVID-19). However, with a better understanding of COVID-19, gastrointestinal symptoms such as diarrhea, nausea, and vomiting have attracted increasing attention. The gastrointestinal tract may be a target organ of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The intestinal microecological balance is a crucial factor for homeostasis, including immunity and inflammation, which are closely related to COVID-19. Herbal medicine can restore intestinal function and regulate the gut flora structure. Herbal medicine has a long history of treating lung diseases from the perspective of the intestine, which is called the gut-lung axis. The physiological activities of guts and lungs influence each other through intestinal flora, microflora metabolites, and mucosal immunity. Microecological modulators are included in the diagnosis and treatment protocols for COVID-19. In this review, we demonstrate the relationship between COVID-19 and the gut, gut-lung axis, and the role of herbal medicine in treating respiratory diseases originating from the intestinal tract. It is expected that the significance of herbal medicine in treating respiratory diseases from the perspective of the intestinal tract could lead to new ideas and methods for treatment.

Graphical abstract

http://links.lww.com/AHM/A33.

An overview on in vitro and in vivo antiviral activity of lactoferrin: its efficacy against SARS-CoV-2 infection

Beyond the absolute and indisputable relevance and efficacy of anti-SARS-CoV-2 vaccines, the rapid transmission, the severity of infection, the absence of the protection on immunocompromised patients, the propagation of variants, the onset of infection and/or disease in vaccinated subjects and the lack of availability of worldwide vaccination require additional antiviral treatments. Since 1987, lactoferrin (Lf) is well-known to possess an antiviral activity related to its physico-chemical properties and to its ability to bind to both heparan sulfate proteoglycans (HSPGs) of host cells and/or surface components of viral particles. In the present review, we summarize in vitro and in vivo studies concerning the efficacy of Lf against DNA, RNA, enveloped and non-enveloped viruses. Recent studies have revealed that the in vitro antiviral activity of Lf is also extendable to SARS-CoV-2. In vivo, Lf oral administration in early stage of SARS-CoV-2 infection counteracts COVID-19 pathogenesis. In particular, the effect of Lf on SARS-CoV-2 entry, inflammatory homeostasis, iron dysregulation, iron-proteins synthesis, reactive oxygen formation, oxidative stress, gut-lung axis regulation as well as on RNA negativization, and coagulation/fibrinolysis balance will be critically reviewed. Moreover, the molecular mechanisms underneath, including the Lf binding to HSPGs and spike glycoprotein, will be disclosed and discussed. Taken together, present data not only support the application of the oral administration of Lf alone in asymptomatic COVID-19 patients or as adjuvant of standard of care practice in symptomatic ones but also constitute the basis for enriching the limited literature on Lf effectiveness for COVID-19 treatment.

Forsythiae Fructuse extracts alleviates LPS-induced acute lung injury in mice by regulating PPAR-γ/RXR-α in lungs and colons

ETHNOPHARMACOLOGICAL RELEVANCE

Forsythiae Fructuse (FF), the dried fruit of Forsythia suspensa (Thunb.) Vahl, is used as a traditional Chinese medicine that has been reported to exert good anti-inflammatory effects in the treatment of many lung diseases.

AIM OF THE STUDY

The purpose of this study was to investigate the anti-inflammatory mechanism of FF in the treatment of acute lung injury (ALI) based on gut-lung axis.

MATERIALS AND METHODS

ALI model was established by the intratracheal instillation of 5 mg/kg LPS in ICR mice. Mice were administered intragastrically with dexamethasone (DEX), and low-dose, medium-dose and high-dose of FF extracts (LFF, MFF and HFF) in addition to the mice of control (CON) and model (MOD) groups. Pathological observation and inflammation scoring of lung tissues were based on HE staining. Limulus lysate assay was used to detect endotoxin levels in serum. Western blot and Real-time quantitative PCR were respectively applied to detect the protein and mRNA expressions in both lung and colon tissues.

RESULTS

Lung pathological injury, inflammatory score and inflammatory genes (IL-6, IL-1β, TNF-α) could be effectively suppressed by FF in LPS-induced ALI mice. FF also increased the proteins of epithelial markers (E-cadherin, ZO-1 and Claudin-1) in lung and colon tissues, and decreased colonic inflammatory genes for protecting the epithelial barriers of lung and colon. The protein expression of TLR4/MAPK/NF-κB inflammatory signaling pathway in lung and colon was significantly inhibited by FF via the regulation of PPAR-γ, a nuclear hormone receptor that forms the heterodimer with RXR-α to inhibit inflammatory gene transcription. More specifically, FF promoted the upregulation of protein, phosphorylated proteins and genes of PPAR-γ/RXR-α in lungs, while inhibited the protein overexpression and phosphorylation of PPAR-γ/RXR-α in colons.

CONCLUSIONS

FF exhibited anti-inflammatory effects and protected the epithelial barriers in lungs and colons by regulating PPAR-γ/RXR-α in the treatment of LPS-induced ALI.

The gut-lung axis in severe acute Pancreatitis-associated lung injury: The protection by the gut microbiota through short-chain fatty acids

The role of gut microbiota in regulating the intestinal homeostasis, as well as the pathogenesis of severe acute pancreatitis-associated lung injury (PALI) is widely recognized. The bioactive functions of metabolites with small molecule weight and the detail molecular mechanisms of PALI mediated by "gut-lung axis" have gradually raised the attentions of researchers. Several studies have proved that short-chain fatty acids (SCFAs) produced by gut microbiome play crucial roles and varied activities in the process of PALI. However, relevant reviews reporting SCFAs in the involvement of PALI is lacking. In this review, we firstly introduced the synthetic and metabolic pathways of SCFAs, as well as the transport and signal transduction routes in brief. Afterwards, we focused on the possible mechanisms and clues of SCFAs to participate in the fight against PALI which referred to the inhibition of pathogen proliferation, anti-inflammatory effects, enhancement of intestinal barrier functions, and the maintenance and regulation of immune homeostasis via pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). In addition, the latest reported pathological and physiological mechanisms of the gut-lung axis involved in PALI were reviewed. Finally, we summarized the potential therapeutic interventions of PALI by targeting SCFAs, including dietary fiber supplementation, direct supplementation of SCFAs/prebiotics/probiotics, and drugs administration, which is expected to provide new sights for clinical use in the future.

The treatment of Qibai Pingfei Capsule on chronic obstructive pulmonary disease may be mediated by Th17/Treg balance and gut-lung axis microbiota

BACKGROUND

Chronic obstructive pulmonary disease (COPD), a prevalent, progressive respiratory disease, has become the third leading cause of death globally. Increasing evidence suggests that intestinal and pulmonary microbiota dysbiosis is associated with COPD. Researchers have shown that T helper (Th) 17/regulatory T (Treg) imbalance is involved in COPD. Qibai Pingfei Capsule (QBPF) is a traditional Chinese medicine used to treat COPD clinically in China. However, the effects of QBPF intervention on the Th17/Treg balance and microbiota in the gut and lung are still poorly understood.

METHODS

This study divided the rats into three groups (n = 8): control, model, and QBPF group. After establishing the model of COPD for four weeks and administering of QBPF for two weeks, Th17 cells, Treg cells, their associated cytokines, transcription factors, and intestinal and pulmonary microbiota of rats were analyzed. Furthermore, the correlations between intestinal and pulmonary microbiota and between bacterial genera and pulmonary function and immune function were measured.

RESULTS

The results revealed that QBPF could improve pulmonary function and contribute to the new balance of Th17/Treg in COPD rats. Meanwhile, QBPF treatment could regulate the composition of intestinal and pulmonary microbiota and improve community structure in COPD rats, suppressing the relative abundance of Coprococcus_2, Prevotella_9, and Blautia in the gut and Mycoplasma in the lung, but accumulating the relative abundance of Prevotellaceae_UCG_003 in the gut and Rikenellaceae_RC9_gut_group in the lung. Additionally, gut-lung axis was confirmed by the significant correlations between the intestinal and pulmonary microbiota. Functional analysis of microbiota showed amino acid metabolism was altered in COPD rats in the gut and lung. Spearman correlation analysis further enriched the relationship between the microbiota in the gut and lung and pulmonary function and immune function in COPD model rats.

CONCLUSIONS

Our study indicated that the therapeutic effects of QBPF may be achieved by maintaining the immune cell balance and regulating the gut-lung axis microbiota, providing references to explore the potential biomarkers of COPD and the possible mechanism of QBPF to treat COPD.

Crosstalk between gut microbiota and lung inflammation in murine toxicity models of respiratory exposure or co-exposure to carbon nanotube particles and cigarette smoke extract

Carbon nanotubes (CNTs) are emerging environmental and occupational toxicants known to induce lung immunotoxicity. While the underlying mechanisms are evolving, it is yet unknown whether inhaled CNTs would cause abnormalities in gut microbiota (dysbiosis), and if such microbiota alteration plays a role in the modulation of CNT-induced lung immunotoxicity. It is also unknown whether co-exposure to tobacco smoke will modulate CNT effects. We compared the effects of lung exposure to multi-wall CNT, cigarette smoke extract (CSE), and their combination (CNT + CSE) in a 4-week chronic toxicity mouse model. The exposures induced differential perturbations in gut microbiome as evidenced by altered microbial α- and β- diversity, indicating a lung-to-gut communication. The gut dysbiosis due to CNTs, unlike CSE, was characterized by an increase in Firmicutes/Bacteroidetes ratio typically associated with proinflammatory condition. Notably, while all three exposures reduced Proteobacteria, the CNT exposure and co-exposure induced appearance of Tenericutes and Cyanobacteria, respectively, implicating them as potential biomarkers of exposure. CNTs differentially induced certain lung proinflammatory mediators (TNF-α, IL-1β, CCL2, CXCL5) whereas CNTs and CSE commonly induced other mediators (CXCL1 and TGF-β). The co-exposure showed either a component-dominant effect or a summative effect for both dysbiosis and lung inflammation. Depletion of gut microbiota attenuated both the differentially-induced and commonly-induced (TGF-β) lung inflammatory mediators as well as granulomas implying gut-to-lung communication and a modulatory role of gut dysbiosis. Taken together, the results demonstrated gut dysbiosis as a systemic effect of inhaled CNTs and provided the first evidence of a bidirectional gut-lung crosstalk modulating CNT lung immunotoxicity.

Air pollution and endocrine disruptors induce human microbiome imbalances: A systematic review of recent evidence and possible biological mechanisms

A rich body of literature indicates that environmental factors interact with the human microbiome and influence its composition and functions contributing to the pathogenesis of diseases in distal sites of the body. This systematic review examines the scientific evidence on the effect of environmental toxicants, air pollutants and endocrine disruptors (EDCs), on compositional and diversity of human microbiota. Articles from PubMed, Embase, WoS and Google Scholar where included if they focused on human populations or the SHIME® model, and assessed the effects of air pollutants and EDCs on human microbiome. Non-human studies, not written in English and not displaying original research were excluded. The Newcastle-Ottawa Scale was used to assess the quality of individual studies. Results were extracted and presented in tables. 31 studies were selected, including 24 related to air pollutants, 5 related to EDCs, and 2 related to EDC using the SHIME® model. 19 studies focussed on the respiratory system (19), gut (8), skin (2), vaginal (1) and mammary (1) microbiomes. No sufficient number of studies are available to observe a consistent trend for most of the microbiota, except for streptococcus and veillionellales for which 9 out of 10, and 3 out of 4 studies suggest an increase of abundance with exposure to air pollution. A limitation of the evidence reviewed is the scarcity of existing studies assessing microbiomes from individual systems. Growing evidence suggests that exposure to environmental contaminants could change the diversity and abundance of resident microbiota, e.g. in the upper and lower respiratory, gastrointestinal, and female reproductive system. Microbial dysbiosis might lead to colonization of pathogens and outgrowth of pathobionts facilitating infectious diseases. It also might prime metabolic dysfunctions disrupting the production of beneficial metabolites. Further studies should elucidate the role of environmental pollutants in the development of dysbiosis and dysregulation of microbiota-related immunological processes.

Evidences and perspectives of the use of probiotics, prebiotics, synbiotics, and postbiotics as adjuvants for prevention and treatment of COVID-19: A bibliometric analysis and systematic review

BACKGROUND

Coronavirus disease-19 (COVID-19) is an infectious disease transmitted by the virus responsible for the severe acute respiratory syndrome 2 (SARS-CoV-2), which exhibit several clinical manifestations including gastrointestinal symptoms.

SCOPE AND APPROACH

This review aimed to provide insights and perspectives for the use of probiotics, prebiotics, synbiotics, and postbiotics as adjuvants for prevention/treatment and/or modulation of the microbiota in COVID-19 patients. Eighty-four studies published in the Scopus database from the onset of the pandemic until December 2021 were assessed and submitted to a bibliometric analysis adapted from VOSviewer software.

KEY FINDINGS AND CONCLUSIONS

Through bibliometric analysis, it might be suggested that the modulation of the gut/lung microbiome is promising as an adjuvant for the prevention/treatment of COVID-19 patients, due to immunomodulation properties related to probiotics and prebiotics. So far, few clinical studies involving the application of probiotics in COVID-19 patients have been completed, but reduction in the duration of the disease and the severity of symptoms as fatigue, olfactory dysfunction and breathlessness, nausea and vomiting and other gastrointestinal symptoms were some of the main findings. However, probiotics are not recommended to immunocompromised patients in corticosteroid therapy. The future perspectives point to the modulation of the intestinal microbiota by probiotics, prebiotics, synbiotics, and postbiotics represent a promising adjuvant approach for improving the health of patients with COVID-19.

Remote regulation of type 2 immunity by intestinal parasites

The intestinal tract is the target organ of most parasitic infections, including those by helminths and protozoa. These parasites elicit prototypical type 2 immune activation in the host's immune system with striking impact on the local tissue microenvironment. Despite local containment of these parasites within the intestinal tract, parasitic infections also mediate immune adaptation in peripheral organs. In this review, we summarize the current knowledge on how such gut-tissue axes influence important immune-mediated resistance and disease tolerance in the context of coinfections, and elaborate on the implications of parasite-regulated gut-lung and gut-brain axes on the development and severity of airway inflammation and central nervous system diseases.

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

Trillions of beneficial and hostile microorganisms live in the human respiratory and gastrointestinal tracts, which act as gatekeepers in maintaining human health, i.e., protecting the body from pathogens by colonizing mucosal surfaces with microbiota-derived antimicrobial metabolites such as short-chain fatty acids or host-derived cytokines and chemokines. It is widely accepted that the microbiome interacts with each other and with the host in a mutually beneficial relationship. Microbiota in the respiratory tract may also play a crucial role in immune homeostasis, maturation, and maintenance of respiratory physiology. Anti-TB antibiotics may cause dysbiosis in the lung and intestinal microbiota, affecting colonization resistance and making the host more susceptible to Mycobacterium tuberculosis (M. tuberculosis) infection. This review discusses recent advances in our understanding of the lung microbiota composition, the lungs and intestinal microbiota related to respiratory health and diseases, microbiome sequencing and analysis, the bloodstream, and the lymphatic system that underpin the gut-lung axis in M. tuberculosis-infected humans and animals. We also discuss the gut-lung axis interactions with the immune system, the role of the microbiome in TB pathogenesis, and the impact of anti-TB antibiotic therapy on the microbiota in animals, humans, and drug-resistant TB individuals.

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.

Current knowledge about the connection between health status and gut microbiota from birth to elderly. A narrative review

The human body is colonized from the birth by a large number of microorganisms. This will constitute a real "functional microbial organ" that is fundamental for homeostasis and therefore for health in humans. Those microorganisms. The microbial populations that colonize humans creating a specific ecosystem they have been collectively referred to as "human microbiota" or "human normal microflora". The microbiota play an important pathophysiological role in the various locations of the human body. This article focuses on one of the most important, that is the enteric microbiota. The composition (quantitative and qualitative) of microbes is analyzed in relation to age and environment during the course of human life. It also highlights eubiosis and dysbiosis as key terms for its role in health and disease. Finally, it analyzes its bi-directional relationship with the microbiota of the lungs, skin and that of the brain, and consequently for the whole central and peripheral nervous system for the maintenance of health in the human body.

The microbiota-mediated dietary and nutritional interventions for COVID-19

Worldwide, scientists are looking for specific treatment for COVID-19. Apart from the antiviral approach, the interventions to support healthy immune responses to the virus are feasible through diet, nutrition, and lifestyle approaches. This narrative review explores the recent studies on dietary, nutritional, and lifestyle interventions that influence the microbiota-mediated immunomodulatory effects against viral infections. Cumulative studies reported that the airway microbiota and SARS-CoV-2 leverage each other and determine the pathogen-microbiota-host responses. Cigarette smoking can disrupt microbiota abundance. The composition and diversification of intestinal microbiota influence the airway microbiota and the innate and adaptive immunity, which require supports from the balance of macro- and micronutrients from the diet. Colorful vegetables supplied fermentable prebiotics and anti-inflammatory, antioxidant phytonutrients. Fermented foods and beverages support intestinal microbiota. In sensitive individuals, the avoidance of the high immunoreactive food antigens contributes to antiviral immunity. This review suggests associations between airway and intestinal microbiota, antiviral host immunity, and the influences of dietary, nutritional, and lifestyle interventions to prevent the clinical course toward severe COVID-19.

Making a complex dental care tailored to the person: population health in focus of predictive, preventive and personalised (3P) medical approach

An evident underestimation of the targeted prevention of dental diseases is strongly supported by alarming epidemiologic statistics globally. For example, epidemiologists demonstrated 100% prevalence of dental caries in the Russian population followed by clinical manifestation of periodontal diseases. Inadequately provided oral health services in populations are caused by multi-factorial deficits including but not limited to low socio-economic status of affected individuals, lack of insurance in sub-populations, insufficient density of dedicated medical units. Another important aspect is the “participatory” medicine based on the active participation of population in maintaining oral health: healthcare will remain insufficient as long as the patient is not motivated and does not feel responsible for their oral health. To this end, nearly half of chronically diseased people do not comply with adequate medical services suffering from severely progressing pathologies. Noteworthy, the prominent risk factors and comorbidities linked to the severe disease course and poor outcomes in COVID-19-infected individuals, such as elderly, diabetes mellitus, hypertension and cardiovascular disease, are frequently associated with significantly altered oral microbiome profiles, systemic inflammatory processes and poor oral health. Suggested pathomechanisms consider potential preferences in the interaction between the viral particles and the host microbiota including oral cavity, the respiratory and gastrointestinal tracts. Since an aspiration of periodontopathic bacteria induces the expression of angiotensin-converting enzyme 2, the receptor for SARS-CoV-2, and production of inflammatory cytokines in the lower respiratory tract, poor oral hygiene and periodontal disease have been proposed as leading to COVID-19 aggravation. Consequently, the issue-dedicated expert recommendations are focused on the optimal oral hygiene as being crucial for improved individual outcomes and reduced morbidity under the COVID-19 pandemic condition. Current study demonstrated that age, gender, socio-economic status, quality of environment and life-style, oral hygiene quality, regularity of dental services requested, level of motivation and responsibility for own health status and corresponding behavioural patterns are the key parameters for the patient stratification considering person-tailored approach in a complex dental care in the population. Consequently, innovative screening programmes and adapted treatment schemes are crucial for the complex person-tailored dental care to improve individual outcomes and healthcare provided to the population.

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.

Intestinal mycobiota in health and diseases: from a disrupted equilibrium to clinical opportunities

Bacteria, viruses, protozoa, and fungi establish a complex ecosystem in the gut. Like other microbiota, gut mycobiota plays an indispensable role in modulating intestinal physiology. Notably, the most striking characteristics of intestinal fungi are their extraintestinal functions. Here, we provide a comprehensive review of the importance of gut fungi in the regulation of intestinal, pulmonary, hepatic, renal, pancreatic, and brain functions, and we present possible opportunities for the application of gut mycobiota to alleviate/treat human diseases. Video Abstract.

A meta-analysis reveals the effectiveness of probiotics and prebiotics against respiratory viral infection

Experimental experience suggests that microbial agents including probiotics and prebiotics (representative microbial agents) play a critical role in defending against respiratory virus infection. We aim to systematically examine these agents' effect on respiratory viral infection and encourage research into clinical applications. An electronic literature search was conducted from published data with a combination of a microbial agents search component containing synonyms for microbial agents-related terms and a customized search component for respiratory virus infection. Hazard ratio (HR), risk ratio (RR) and standard deviation (SD) were employed as effect estimates. In 45 preclinical studies, the mortality rates decreased in the respiratory viral infection models that included prebiotics or prebiotics as interventions (HR: 0.70; 95% confidence interval (CI): 0.56-0.87; P=0.002). There was a significant decrease in viral load due to improved gut microbiota (SD: -1.22; 95% CI: -1.50 to -0.94; P<0.001). Concentrations of interferon (IFN)-α (SD: 1.05; 95% CI: 0.33-1.77; P=0.004), IFN-γ (SD: 0.83; 95% CI: 0.01-1.65; P=0.05) and interleukin (IL)-12 (SD: 2.42; 95% CI: 0.32-4.52; P=0.02), IL-1β (SD: 0.01; 95% CI: -0.37 to 0.40; P=0.94) increased, whereas those of TNF-α (SD: -0.58; 95% CI: -1.59 to 0.43; P=0.26) and IL-6 (SD: -0.59; 95% CI: -1.24 to 0.07; P=0.08) decreased. Six clinical studies had lower symptom scores (SD: -0.09; 95% CI: -0.44 to 0.26; P=0.61) and less incidence of infection (RR: 0.80; 95% CI: 0.64-1.01; P=0.06). Our research indicates that probiotics and prebiotics pose a defensive possibility on respiratory viral infection and may encourage the clinical application.