Respiratory influenza virus infection induces intestinal immune injury via microbiota-mediated Th17 cell-dependent inflammation

Protein Ubiquitination Modification in Pulmonary Fibrosis

Pulmonary fibrosis (PF) is a chronic, progressive fibrotic interstitial lung disease characterized by a high incidence and mortality rate, which encompasses features, such as diffuse alveolar inflammation, invasive fibroblast activation, and uncontrolled extracellular matrix (ECM) deposition. Beyond the local pathological processes, PF can be better understood in light of interorgan communication networks that are involved in its progression. Notably, pulmonary inflammation can affect cardiovascular, renal, hepatic, and neural functions, highlighting the importance of understanding these systemic interactions. Posttranslational modifications play a crucial role in regulating protein function, localization, stability, and activity. Specifically, protein ubiquitination modifications are involved in PF induced by various stimuli, involving a range of ubiquitin-modifying enzymes and substrates. In this review, we provide an overview of how E3 ubiquitin ligases and deubiquitinating enzymes (DUBs) modulate PF through several signaling pathways, such as TGF-β, Wnt, metabolic activity, aging, ferroptosis, endoplasmic reticulum stress, and inflammatory responses. This perspective includes the role of ubiquitin-proteasome systems in interorgan communication, affecting the progression of PF and related systemic conditions. Additionally, we also summarize the currently available therapeutic compounds targeting protein ubiquitination-related enzymes or ubiquitination substrates for the treatment of PF. Understanding the interplay between ubiquitination and interorgan communication may pave the way for novel therapeutic strategies.

Nasal vaccines for respiratory infections

Beginning with Edward Jenner's discovery of the smallpox vaccine, the ever-expanding repertoire of vaccines against pathogens has saved many lives. During the COVID-19 pandemic, a revolutionary mRNA injectable vaccine emerged that effectively controlled the severity of disease caused by SARS-CoV-2. This vaccine induced potent antigen-specific neutralizing serum IgG antibodies, but was limited in its ability to prevent viral invasion at the respiratory surfaces. Nasal vaccines have attracted attention as a potential strategy to combat respiratory infections and prepare for future pandemics. Input from disciplines such as microbiology, biomaterials, bioengineering and chemistry have complemented the immunology to create innovative delivery systems. This approach to vaccine delivery has yielded nasal vaccines that induce secretory IgA as well as serum IgG antibodies, which are expected to prevent pathogen invasion, thereby diminishing transmission and disease severity. For a nasal vaccine to be successful, the complexity of the relevant anatomical, physiological and immunological properties, including the proximity of the central nervous system to the nasal cavity, must be considered. In this Review, we discuss past and current efforts as well as future directions for developing safe and effective nasal vaccines for the prevention of respiratory infections.

Gut microbiota contributes to protection against porcine deltacoronavirus infection in piglets by modulating intestinal barrier and microbiome

BACKGROUND

Gut microbiota plays a critical role in counteracting enteric viral infection. Our previous study demonstrated that infection of porcine deltacoronavirus (PDCoV) disturbs gut microbiota and causes intestinal damage and inflammation in piglets. However, the influence of gut microbiota on PDCoV infection remains unclear.

RESULTS

Firstly, the relationship between gut microbiota and disease severity of PDCoV infection was evaluated using 8-day-old and 90-day-old pigs. The composition of gut microbiota was significantly altered in 8-day-old piglets after PDCoV infection, leading to severe diarrhea and intestinal damage. In contrast, PDCoV infection barely affected the 90-day-old pigs. Moreover, the diversity (richness and evenness) of microbiota in 90-day-old pigs was much higher compared to the 8-day-old piglets, suggesting the gut microbiota is possibly associated with the severity of PDCoV infection. Subsequently, transplanting the fecal microbiota from the 90-day-old pigs to the 3-day-old piglets alleviated clinical signs of PDCoV infection, modulated the diversity and composition of gut microbiota, and maintained the physical and chemical barrier of intestines. Additionally, metabolomic analysis revealed that the fecal microbiota transplantation (FMT) treatment upregulated the swine intestinal arginine biosynthesis, FMT significantly inhibited the inflammatory response in piglet intestine by modulating the TLR4/MyD88/NF-κB signaling pathway.

CONCLUSIONS

PDCoV infection altered the structure and composition of the gut microbiota in neonatal pigs. FMT treatment mitigated the clinical signs of PDCoV infection in the piglets by modulating the gut microbiota composition and intestinal barrier, downregulating the inflammatory response. The preventive effect of FMT provides novel targets for the development of therapeutics against enteropathogenic coronaviruses. Video Abstract.

Viral metagenomics reveals diverse viruses in the fecal samples of children with acute respiratory infection

Introduction

Changes in the gut microbiome have been associated with the development of acute respiratory infection (ARI). However, due to methodological limitations, our knowledge of the gut virome in patients with ARIs remains limited.

Methods

In this study, fecal samples from children with ARI were investigated using viral metagenomics.

Results

The fecal virome was analyzed, and several suspected disease-causing viruses were identified. The five viral families with the highest abundance of sequence reads were Podoviridae, Virgaviridae, Siphoviridae, Microviridae, and Myoviridae. Additionally, human adenovirus, human bocavirus, human astrovirus, norovirus, and human rhinovirus were detected. The genome sequences of these viruses were respectively described, and phylogenetic trees were constructed using the gene sequences of the viruses.

Discussion

We characterized the composition of gut virome in children with acute respiratory infections. However, further research is required to elucidate the relationship between acute respiratory infection and gut viruses.

Concurrent Circulation of Viral Agents in Pediatric Patients Presenting with Respiratory Illness and Diarrheal Symptoms in Metropolitan Region of São Paulo, Brazil, 2021

Pneumonia and diarrhea are the leading causes of death in children under 5 globally, worsened by viral infections. This study investigates viral agents in children ≤ 3 years with respiratory illness and diarrhea in Metropolitan Region of São Paulo, Brazil, during spring 2021. Twenty paired samples (oropharyngeal swab and feces) were tested using in-house qPCR for HBoV and HAdV, RT-qPCR for RVA, EV, PeV-A, and NoV, and a commercial RT-qPCR kit for SARS-CoV-2, Flu A/B, and RSV. HAstV was detected with conventional nested (RT)-PCR. Positive samples were sequenced for molecular characterization and phylogenetic analysis. Seven viruses were identified: HBoV, NoV, HAdV, PeV-A, EV, RSV, and Flu A. HBoV and NoV were detected in 75% of cases, with co-infection in 65% of patients, indicating their involvement in the gastro-respiratory illness. Genotyping of HBoV (HBoV-1), NoV (GII.4_Sydney[P16], GII.2[P16], and GII.4_Sydney[P31]), EV (Coxsackievirus A6), HAdV (species C, type 6), and PeV-A (genotype 1) showed local virus diversity. Phylogenetic analysis indicated no ongoing community outbreak, with distinct clusters observed. The findings highlight the overlap of respiratory and enteric diseases, revealing local viral diversity and high exposure to enteric viruses. This underscores the challenges in differential diagnosis and the need for syndromic surveillance.

Virus-induced perturbations in the mouse microbiome are impacted by microbial experience

The bacterial microbiome has a major impact on health and can shape metabolism, host tolerance, immune responses, and the outcome of future infections. The bacterial microbiome is highly variable between individuals. Specific pathogen-free animals have reduced microbiome diversity, making it difficult to evaluate the impact of infection-induced microbiome disruption that would be observed in free-living animals, including people. Mice are commonly used as a preclinical model but unfortunately often fail to predict translation success or failure, particularly for immune and infectious disease-targeting therapies. Here, we utilize pet store mouse cohoused "dirty" mice with diverse microbial experience to explore how host variability and infection may be interacting to drive unique microbiome changes. We found that cohoused animals had significantly increased bacterial diversity in the small intestine and cecum but not in the large intestine. There were differentially abundant taxa between clean and dirty animals in all three tissues. After infection with influenza A virus, samples clustered by both housing condition and infection status in the cecum and large intestine, while small intestine samples clustered predominantly by infection. Altogether, these results highlight the differential impact of housing, infection, and interaction between the two in dictating community composition across the gastrointestinal microbiome.IMPORTANCETraditionally housed pathogen-free mouse models do not fully capture the natural variability observed among human microbiomes, which may underlie their poor translationally predictive value. Understanding the difference between pathogen-induced shifts in the bacterial microbiome and natural microbiome variance is a major hurdle to determining bacterial biomarkers of disease. It is also critical to understand how diverse baseline microbiomes may be differentially impacted by infection and contribute to disease. Pet store cohoused "dirty" mice have diverse microbial experiences and microbiomes, allowing us to evaluate how baseline variation, infection, and interaction between the two impact the microbiome.

Intestinal-pulmonary axis: a 'Force For Good' against respiratory viral infections

Respiratory viral infections are a major global public health concern, and current antiviral therapies still have limitations. In recent years, research has revealed significant similarities between the immune systems of the gut and lungs, which interact through the complex physiological network known as the "gut-lung axis." As one of the largest immune organs, the gut, along with the lungs, forms an inter-organ immune network, with strong parallels in innate immune mechanisms, such as the activation of pattern recognition receptors (PRRs). Furthermore, the gut microbiota influences antiviral immune responses in the lungs through mechanisms such as systemic transport of gut microbiota-derived metabolites, immune cell migration, and cytokine regulation. Studies have shown that gut dysbiosis can exacerbate the severity of respiratory infections and may impact the efficacy of antiviral therapies. This review discusses the synergistic role of the gut-lung axis in antiviral immunity against respiratory viruses and explores potential strategies for modulating the gut microbiota to mitigate respiratory viral infections. Future research should focus on the immune mechanisms of the gut-lung axis to drive the development of novel clinical treatment strategies.

Intestinal IL-17 family orchestrates microbiota-driven histone deacetylation and promotes Treg differentiation to mediate the alleviation of asthma by Ma-Xing-Shi-Gan decoction

BACKGROUND

Gut microbiota imbalance is well-known as one important trigger of allergic asthma. Ma-Xing-Shi-Gan decoction (MXSG) is a traditional Chinese medicine prescription with ideal clinical efficacy on asthma. However, whether and how MXSG exerts its efficacy on asthma through gut microbiota remains unclear.

PURPOSE

To investigate the underlying mechanism of MXSG against asthma using multi-omics technologies.

METHODS

An asthma model was established using 8-week-old C57BL/6 J mice, after which they were daily administrated with high-, medium- and low-dose MXSG for 7 days. Histopathological examinations and flow cytometry were performed to evaluate the effects of MXSG on lung immune injury. Key regulatory pathways were predicted via network pharmacology and verified using 16S rRNA sequencing, metagenomics, metabolomics, and in vivo experiments including the knockout of the targeting gene.

RESULTS

MXSG alleviated asthma symptoms, elevated intestinal microbial diversities, and enriched potential beneficial microbes such as Lactococcus, Lactobacillus, and Limosilactobacillus. Network pharmacology and experimental validation highlighted the IL-17/Treg signaling as crucial for asthma treatment. IL-17 knockout experiments revealed its necessity for Treg differentiation during asthma. Moreover, IL-17-deficient asthmatic mice exhibited lower levels of Lactobacillus and significant changes in microbial genes involving histone deacetylases (HDAC) and short-chain fatty acids (SCFAs). Finally, MXSG significantly boosted SCFA production and reduced HDAC9 expression, which were correlated with Treg cell ratios.

CONCLUSION

Our study delineates a novel mechanism where MXSG synergizes with the IL-17 family to enrich intestinal beneficial microbes (e.g. Lactobacillus) and SCFAs. This inhibits the expression of SCFA-downstream HDAC9 to promote Treg differentiation, and thus potentially alleviates asthma.

Oral probiotic extracellular vesicle therapy mitigates Influenza A Virus infection via blunting IL-17 signaling

The influenza A virus (IAV) damages intestinal mucosal tissues beyond the respiratory tract. Probiotics play a crucial role in maintaining the balance and stability of the intestinal microecosystem. Extracellular vesicles (EVs) derived from probiotics have emerged as potential mediators of host immune response and anti-inflammatory effect. However, the specific anti-inflammatory effects and underlying mechanisms of probiotics-derived EVs on IAV remain unclear. In the present study, we investigated the therapeutic efficacy of Lactobacillus reuteri EHA2-derived EVs (LrEVs) in a mouse model of IAV infection. Oral LrEVs were distributed in the liver, lungs, and gastrointestinal tract. In mice infected with IAV, oral LrEVs administration alleviated IAV-induced damages in the lungs and intestines, modified the microbiota compositions, and increased the levels of short-chain fatty acids in those organs. Mechanistically, LrEVs exerted their protective effects against IAV infection by blunting the pro-inflammatory IL-17 signaling. Furthermore, FISH analysis detected miR-4239, one of the most abundant miRNAs in LrEVs, in both lung and intestinal tissues. We confirmed that miR-4239 directly targets IL-17a. Our findings paved the ground for future application of LrEVs in influenza treatment and offered new mechanistic insights regarding the anti-inflammatory role of miR-4239.

Role of Gut Microbiota in Long COVID: Impact on Immune Function and Organ System Health

SARS-CoV-2 infection has led to a range of long-lasting symptoms, collectively referred to as long COVID. Current research highlights the critical role of angiotensin-converting enzyme 2 (ACE2) in regulating gut microbiota diversity, vascular function, and homeostasis within the renin-angiotensin system (RAS). ACE2 is utilized by the SARS-CoV-2 virus to enter host cells, but its downregulation following infection contributes to gut microbiota dysbiosis and RAS disruption. These imbalances have been linked to a range of long COVID symptoms, including joint pain, chest pain, chronic cough, fatigue, brain fog, anxiety, depression, myalgia, peripheral neuropathy, memory difficulties, and impaired attention. This review investigates the dysregulation caused by SARS-CoV-2 infection and the long-term effects it has on various organ systems, including the musculoskeletal, neurological, renal, respiratory, and cardiovascular systems. We explored the bidirectional interactions between the gut microbiota, immune function, and these organ systems, focusing on how microbiota dysregulation contributes to the chronic inflammation and dysfunction observed in long COVID symptoms. Understanding these interactions is key for identifying effective therapeutic strategies and interventional targets aimed at mitigating the impact of long COVID on organ health and improving patient outcomes.

Influenza a virus subtype H9N2 infection induces respiratory microbiota dysbiosis in chickens via type-I interferon-mediated mechanisms

Avian influenza virus (AIV) poses significant threats to poultry and human health. This study investigates the impact of H9N2 AIV infection on the respiratory microbiota of chickens using 16S rRNA gene sequencing. Total 48 one-day-old specific pathogen-free chickens were assigned to six groups: a control and five post-infection groups (days 1, 3, 5, 7, and 9). After a 15-day microbiota stabilization period, the infected chickens received a viral inoculum (107 TCID50/ml) via ocular, intra-nasal, and intra-tracheal routes. Tracheal and broncho-alveolar lavage samples were analyzed. Significant reductions in microbiota diversity were observed on days 5, 7, and 9 post-infection, compared to d0 controls. Permutational Multivariate Analysis of Variance confirmed significant beta diversity differences (P = 0.001) between infected and uninfected groups. The microbial shifts from d5 to d9 were marked by increased Proteobacteria, decreased Actinobacteria and Firmicutes, and a rise in Dickeya. Elevated type-I interferon (IFN-β) and viperin gene expression at d5 coincided with reduced microbiota diversity, highlighting the respiratory microbiota's role in modulating host responses to AIV H9N2 infection and suggesting potential biomarkers for respiratory dysbiosis.

A Review on miRNAs in Enteric Bacteria-mediated Host Pathophysiology: Mechanisms and Implications

Recently, many studies focused on the billions of native bacteria found inside and all over the human body, commonly known as the microbiota, and its interactions with the eukaryotic host. One of the niches for such microbiota is the gastrointestinal tract (GIT), which harbors hundreds to thousands of bacterial species commonly known as enteric bacteria. Changes in the enteric bacterial populations were linked to various pathologies such as irritable bowel syndrome and obesity. The gut microbiome could affect the health status of individuals. MicroRNAs (miRNAs) are one of the extensively studied small-sized noncoding RNAs (ncRNAs) over the past decade to explore their multiple roles in health and disease. It was proven that miRNAs circulate in almost all body fluids and tissues, showing signature patterns of dysregulation associated with pathologies. Both cellular and circulating miRNAs participate in the posttranscriptional regulation of genes and are considered the potential key regulators of genes and participate in cellular communication. This manuscript explores the unique interplay between miRNAs and enteric bacteria in the gastrointestinal tract, emphasizing their dual role in shaping host-microbiota dynamics. It delves into the molecular mechanisms by which miRNAs influence bacterial colonization and host immune responses, linking these findings to gut-related diseases. The review highlights innovative therapeutic and diagnostic opportunities, offering insights for targeted treatments of dysbiosis-associated pathologies.

Is Nasal Dysbiosis a Required Component for Neuroinflammation in Major Depressive Disorder?

Human microbiota is known to influence immune and cerebral responses by direct and/or indirect mechanisms, including hypothalamic-pituitary-adrenal axis signaling, activation of neural afferent circuits to the brain, and by altering the peripheral immune responses (cellular and humoral immune function, circulatory inflammatory cells, and the production of several inflammatory mediators, such as cytokines, chemokines, and reactive oxygen species). The inflammatory responses in the nasal mucosa (rhinitis) or paranasal sinuses (chronic rhinosinusitis) are dual conditions related with a greater risk for developing depression. In the nasal cavity, anatomic components of the olfactive function are in direct contact with the CNS through the olfactory receptors, neurons, and axons that end in the olfactory bulb and the entorhinal cortex. Local microbiome alterations (dysbiosis) are linked to transepithelial translocation of microorganisms and their metabolites, which disrupts the epithelial barrier and favors vascular permeability, increasing the levels of several inflammatory molecules (both cytokines and non-cytokine mediators: extracellular vesicles (exosomes) and neuropeptides), triggering local inflammation (rhinitis) and the spread of these components into the central nervous system (neuroinflammation). In this review, we discuss the role of microbiota-related immunity in conditions affecting the nasal mucosa (chronic rhinosinusitis and allergic rhinitis) and their relevance in major depressive disorders, focusing on the few mechanisms known to be involved and providing some hypothetical proposals on the pathophysiology of depression.

Explore Alteration of Lung and Gut Microbiota in a Murine Model of OVA-Induced Asthma Treated by CpG Oligodeoxynucleotides

Aim

We sought to investigate the impact of CpG oligodeoxynucleotides (CpG-ODN) administration on the lung and gut microbiota in asthmatic mice, specifically focusing on changes in composition, diversity, and abundance, and to elucidate the microbial mechanisms underlying the therapeutic effects of CpG-ODN and identify potential beneficial bacteria indicative of its efficacy.

Methods

HE staining were used to analyze inflammation in lung, colon and small intestine tissues. High-throughput sequencing technology targeting 16S rRNA was employed to analyze the composition, diversity, and correlation of microbiome in the lung, colon and small intestine of control, model and CpG-ODN administration groups.

Results

(1) Histopathologically, both lung and intestinal tissue in asthmatic mice exhibited significant structural damage and inflammatory response, whereas the structure of both lung and intestinal tissue approached normal levels, accompanied by a notable improvement in the inflammatory response after CpG-ODN treatment. (2) In the specific microbiota composition analysis, bacterial dysbiosis observed in the asthmatic mice, accompanied by enrichment of Proteobacteria found to cause lung and intestinal epithelial damage and inflammatory reaction. After CpG-ODN administration, bacterial dysbiosis was improved, and a notable enrichment of beneficial bacteria, indicating a novel microecology. Meanwhile Oscillospira and Clostridium were identified as two biomarkers of the CpG-ODN treatment. (3) Heatmap analysis revealed significant correlations among lung, small intestine, and colon microbiota.

Conclusion

CpG-ODN treatment can ameliorate OVA-induced asthma in mice. One side, preserving the structural integrity of the lung and intestine, safeguarding the mucosal physical barrier, the other side, improving the dysbiosis of lung and gut microbiota in asthmatic mice. Beneficial bacteria and metabolites take up microecological advantages, regulate immune cells and participate in the mucosal immune response to protect the immune barrier. Meanwhile, Oscillospira and Clostridium as biomarkers for CpG-ODN treatment, has reference significance for exploring precise Fecal microbiota transplantation treatment for asthma.

Immune crosstalk between respiratory and intestinal mucosal tissues in respiratory infections

Mucosal tissues, including those in the respiratory and gastrointestinal tracts, are critical barrier surfaces for pathogen invasion. Infections at these sites not only trigger local immune response, but also recruit immune cells from other tissues. Emerging evidence in the mouse models and human samples indicates that the immune crosstalk between the lung and gut critically impacts and determines the course of respiratory disease. Here we summarize the current knowledge of the immune crosstalk between the respiratory and gastrointestinal tracts, and discuss how immune cells are recruited and migrate between these tissues during respiratory infections. We also discuss how commensal bacteria contribute to these processes.

Influenza A virus during pregnancy disrupts maternal intestinal immunity and fetal cortical development in a dose- and time-dependent manner

Epidemiological studies link exposure to viral infection during pregnancy, including influenza A virus (IAV) infection, with increased incidence of neurodevelopmental disorders (NDDs) in offspring. Models of maternal immune activation (MIA) using viral mimetics demonstrate that activation of maternal intestinal T helper 17 (TH17) cells, which produce effector cytokine interleukin (IL)-17, leads to aberrant fetal brain development, such as neocortical malformations. Fetal microglia and border-associated macrophages (BAMs) also serve as potential cellular mediators of MIA-induced cortical abnormalities. However, neither the inflammation-induced TH17 cell pathway nor fetal brain-resident macrophages have been thoroughly examined in models of live viral infection during pregnancy. Here, we inoculated pregnant mice with two infectious doses of IAV and evaluated peak innate and adaptive immune responses in the dam and fetus. While respiratory IAV infection led to dose-dependent maternal colonic shortening and microbial dysregulation, there was no elevation in intestinal TH17 cells nor IL-17. Systemically, IAV resulted in consistent dose- and time-dependent increases in IL-6 and IFN-γ. Fetal cortical abnormalities and global changes in fetal brain transcripts were observable in the high-but not the moderate-dose IAV group. Profiling of fetal microglia and BAMs revealed dose- and time-dependent differences in the numbers of meningeal but not choroid plexus BAMs, while microglial numbers and proliferative capacity of Iba1+ cells remained constant. Fetal brain-resident macrophages increased phagocytic CD68 expression, also in a dose- and time-dependent fashion. Taken together, our findings indicate that certain features of MIA are conserved between mimetic and live virus models, while others are not. Overall, we provide consistent evidence of an infection severity threshold for downstream maternal inflammation and fetal cortical abnormalities, which recapitulates a key feature of the epidemiological data and further underscores the importance of using live pathogens in NDD modeling to better evaluate the complete immune response and to improve translation to the clinic.

Bidirectional association between pneumonia and intestinal infection: an analysis of the MIMIC-IV database

The purpose is to analyze the prevalence of intestinal infection in patients with pneumonia in intensive care units (ICU) and the impact of intestinal infection on the prognosis of patients with pneumonia, so as to explore the bidirectional association between pneumonia and intestinal infection. The study aims to investigate the correlation between the occurrence of pneumonia and intestinal infection among patients in the ICU, utilizing the Medical Information Mart for Intensive Care IV (MIMIC-IV) database, as well as the impact of intestinal infection on the prognosis of pneumonia patients. The enrolled patients were first divided into pneumonia group and non-pneumonia group, and the primary outcome was that patients developed intestinal infection. Multivariate logistic regression was used to elucidate the association between pneumonia and the prevalence of intestinal infection, and propensity score matching (PSM) and inverse probability of treatment weighing (IPTW) were used to validate our findings. We then divided patients with pneumonia into two groups according to whether they were complicated by intestinal infection, and analyzed the effect of intestinal infection on 28-day mortality, length of ICU stay, and length of hospital stay in patients with pneumonia. This study included 50,920 patients, of which 7493 were diagnosed with pneumonia. Compared with non-pneumonia patients, the incidence of intestinal infection in pneumonia patients was significantly increased [OR 1.58 (95% CI 1.34-1.85; P < 0.001)]. Cox proportional hazards regression model showed no significant effect of co-infection on 28-day mortality in patients with pneumonia (P = 0.223). Patients in the intestinal infection group exhibited a longer length stay in ICU and hospital than those without intestinal infection (P < 0.001). In the ICU, patients with pneumonia were more likely linked to intestinal infection. In addition, the presence of concurrent intestinal infections can prolong both ICU and hospital stays for pneumonia patients.

Neutral Polysaccharide from Platycodonis Radix-Ameliorated PM2.5-Induced Lung Injury by Inhibiting the TLR4/NF-κB p65 Pathway and Regulating the Lung and Gut Microbiome

Platycodonis radix (PR) has been reported to play a protective role in lung injury. However, much less is known about the protective effect and mechanism of its main component PR polysaccharides (PRPs) in particulate matter (PM2.5)-induced lung injury. Here, a neutral polysaccharide (MW: 244.56 kDa) was isolated from PR, mainly composed of Rha, Ara, Gal, Glc, Xyl, and Man. PRPs significantly improved PM2.5-induced pulmonary edema, oxidative damage, and cell apoptosis and downregulated inflammatory factor levels in bronchoalveolar lavage fluid. Mechanistically, PRPs reduced intestinal mucosal barrier damage, thereby lowering serum lipopolysaccharide levels and inhibiting the overactivation of the TLR4/NF-κB signaling pathway in the lung tissue. Notably, PRPs could optimize the composition of pulmonary and intestinal microbiota. Oral administration of PRPs resulted in enrichment of short-chain fatty acid (SCFA)-producing bacteria, thereby upregulating the levels of acetate, butyrate, and isovalerate. Taken together, PRPs have great potential in preventing and repairing the lung injury caused by PM2.5.

Emerging concepts in mucosal immunity and oral microecological control of respiratory virus infection-related inflammatory diseases

Oral microecological imbalance is closely linked to oral mucosal inflammation and is implicated in the development of both local and systemic diseases, including those caused by viral infections. This review examines the critical role of the interleukin (IL)-17/helper T cell 17 (Th17) axis in regulating immune responses within the oral mucosa, focusing on both its protective and pathogenic roles during inflammation. We specifically highlight how the IL-17/Th17 pathway contributes to dysregulated inflammation in the context of respiratory viral infections. Furthermore, this review explores the potential interactions between respiratory viruses and the oral microbiota, emphasizing how alterations in the oral microbiome and increased production of proinflammatory factors may serve as early, non-invasive biomarkers for predicting the severity of respiratory viral infections. These findings provide insights into novel diagnostic approaches and therapeutic strategies aimed at mitigating respiratory disease severity through monitoring and modulating the oral microbiome.

Concurrent Klebsiella Bacteremia in Two Infants with Severe Respiratory Syncytial Virus Infection

Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infections in children. In most previously healthy infants, RSV infection is self-limited and resolves without complications. The risk of bacteremia is low in young febrile infants with RSV infection. Herein, we report two previously healthy infants with severe RSV infection who had concurrent Klebsiella bacteremia.

Fei-Yan-Qing-Hua decoction attenuates influenza virus infection by enhancing host antiviral response through microbiota-derived acetate

Background

Fei-Yan-Qing-Hua decoction (FYQHD) is derived from the well-known Ma Xing Shi Gan decoction, which was documented in Zhang Zhong Jing's "Treatise on Exogenous Febrile Disease" during the Han Dynasty. Although FYQHD has been used in the treatment of pneumonia and has demonstrated clinical efficacy for decades, the underlying mechanism by which FYQHD protects against influenza virus infection through modulation of gut flora remains unclear. Here, we examined the regulatory impacts of FYQHD on an influenza virus-infected mouse model and explored the mechanisms involved.

Methods

An infectious mouse model was created by intranasal instillation of influenza A virus (IAV). The effectiveness of FYQHD was assessed through various measures, including weight loss, lung wet/dry ratio, oxidative stress levels, viral load in lung tissues, and intestinal injuries. Changes in gut microbiota and SCFA production were also examined.

Results

The results showed that FYQHD significantly reduced viral load, increased the production of type I interferon (IFN-I), and restored the integrity of the intestinal barrier following IAV challenge. Additionally, FYQHD significantly corrected the dysbiosis of gut microbiota induced by influenza virus infection, enhancing the abundance of SCFA-producing bacteria and acetate production. However, the depletion of gut microbiota significantly attenuated the protective effects of FYQHD against influenza virus infection. In vitro, the antiviral effect of acetate was demonstrated through the upregulation of concentrations of IFN-β.

Conclusion

FYQHD attenuates influenza virus-induced lung and intestinal injuries by boosting the host antiviral response through increasing the abundance of Lachnospiraceae_NK4A136 and Roseburia, along with elevated acetate levels. The study advances our understanding of the therapeutic mechanisms of FYQHD and provides a theoretical basis for the application of FYQHD in the treatment of influenza.

The Influence of the Gut Microbiota on Host Health: A Focus on the Gut-Lung Axis and Therapeutic Approaches

The human gut microbiota is a complex ecosystem harboring thousands of microbial strains that play a crucial role in maintaining the overall well-being of its host. The composition of the gut microbiota varies with age from infancy to adulthood and is influenced by dietary habits, environment, and genetic disposition. Recent advances in culture-independent techniques and nucleic acid sequencing have improved our understanding of the diversity of the gut microbiota. The microbial species present in the gut release short-chain fatty acids (SCFAs), which have anti-inflammatory properties. The gut microbiota also plays a substantial role in modulating the host's immune system, promoting immune tolerance, and maintaining homeostasis. The impact of the gut microbiota on the health of the host is quite evident, as gut dysbiosis has been linked to various diseases, including metabolic disorders, autoimmune diseases, allergies, and inflammatory bowel diseases. The gut microbiota has bidirectional communication with the respiratory system, creating the gut-lung axis, which has been associated with different respiratory diseases. Therapeutic approaches targeting the gut microbiota, such as probiotics, prebiotics, dietary interventions, and fecal microbiota transplantation (FMT), aim to restore microbial balance and promote the growth of beneficial strains in the gut. Nonetheless, gaining knowledge of the complex interactions between the gut microbiota and the host is necessary to develop personalized medicine approaches and microbiota-based therapies for various conditions. This review summarizes studies related to the gut-lung axis with particular emphasis on the role of the microbiota. Future research directions are also discussed.

Abscopal effect: from a rare phenomenon to a new frontier in cancer therapy

Radiotherapy (RT) controls local lesions, meantime it has the capability to induce systemic response to inhibit distant, metastatic, non-radiated tumors, which is referred to as the "abscopal effect". It is widely recognized that radiotherapy can stimulate systemic immune response. This provides a compelling theoretical basis for the combination of immune therapy combined with radiotherapy(iRT). Indeed, this phenomenon has also been observed in clinical treatment, bringing significant clinical benefits to patients, and a series of basic studies are underway to amplify this effect. However, the molecular mechanisms of immune response induced by RT, determination of the optimal treatment regimen for iRT, and how to amplify the abscopal effect. In order to amplify and utilize this effect in clinical management, these key issues require to be well addressed; In this review, we comprehensively summarize the growing consensus and emphasize the emerging limitations of enhancing the abscopal effect with radiotherapy or immunotherapy. Finally, we discuss the prospects and barriers to the current clinical translational applications.

Appendix removal affects the subsequent cancer risk in Asian adults: A territory-wide population-based cohort study

Human appendix is critical for the maintenance of intestinal homeostasis. Appendicectomy has been the optimal treatment of acute appendicitis, yet the cancer incidence after appendix removal remains unclear. In this territory-wide retrospective cohort study, adult participants who underwent appendicectomy from 2000 to 2018 were retrieved from a population database (n = 43,983), while matched reference participants were retrieved as controls (n = 85,853). After appendicectomy, the overall cancer risk was significantly increased (subdistribution hazard ratio (SHR) = 1.124) compared to the non-appendicectomy group. Appendicectomy-treated males had higher cancer risk than males without appendicectomy (SHR = 1.197), while such difference was not observed in female participants. Significant increase in cancer risk was also observed in elder participants (age >60) with appendicectomy (SHR = 1.390). Appendicectomy was positively correlated with the risk of digestive tract and respiratory cancers including colon (SHR = 1.440), pancreas (SHR = 1.930), and trachea, bronchus, and lung (SHR = 1.394). In contrast, the risk of liver cancer was markedly decreased after appendicectomy (SHR = 0.713). In conclusion, we reported the association of appendicectomy with subsequent cancer incidence. These findings highlight the potential complication after appendix removal and the necessity of post-operative management to monitor and prevent long-term adverse events.

Human Infant Fecal Microbiota Differentially Influences the Mucosal Immune Pathways Upon Influenza Infection in a Humanized Gnotobiotic Pig Model

In this study, we evaluated the impact of human gut microbiota on the immune pathways in the respiratory tract using a gnotobiotic (Gn) piglet model. We humanized piglets with rural and urban infant fecal microbiota (RIFM and UIFM, respectively) and then infected them with a H1N1 swine influenza virus. We analyzed the microbial diversity and structure of the intestinal and respiratory tracts of the piglets before and after the influenza virus infection and measured the viral load and immune responses. We found that the viral load in the upper respiratory tract of UIFM transplanted piglets was higher than their rural cohorts (RIFM), while virus-specific antibody responses were comparable. The relative cytokine gene expression in the tracheobronchial (respiratory tract) and mesenteric (gastrointestinal) lymph nodes, lungs, blood, and spleen of RIFM and UIFM piglets revealed a trend in reciprocal regulation of proinflammatory, innate, and adaptive immune-associated cytokines as well as the frequency of T-helper/memory cells, cytotoxic T cells, and myeloid immune cell subsets. We also observed different phylum-level shifts of the fecal microbiota in response to influenza virus infection between the two piglet groups, suggesting the potential impact of the gut microbiota on the immune responses to influenza virus infection and lung microbiota. In conclusion, Gn piglets humanized with diverse infant fecal microbiota had differential immune regulation, with UIFM favoring the activation of proinflammatory immune mediators following an influenza virus infection compared to their rural RIFM cohorts. Furthermore, Gn piglets can be a useful model in investigating the impact of diverse human microbiota of the gastrointestinal tract, probably also the respiratory tract, on respiratory health and testing specific probiotic- or prebiotic-based therapeutics.

Association Between Gut and Nasal Microbiota and Allergic Rhinitis: A Systematic Review

Allergic rhinitis is a chronic non-infectious inflammation of the nasal mucosa mediated by specific IgE. Recently, the human microbiome has drawn broad interest as a potential new target for treating this condition. This paper succinctly summarizes the main findings of 17 eligible studies published by February 2024, involving 1044 allergic rhinitis patients and 954 healthy controls from 5 countries. These studies examine differences in the human microbiome across important mucosal interfaces, including the nasal and intestinal areas, between patients and controls. Overall, findings suggest variations in the gut microbiota between allergic rhinitis patients and healthy individuals, although the specific bacterial taxa that significantly changed were not always consistent across studies. Due to the limited scope of existing research and patient coverage, the relationship between the nasal microbiome and allergic rhinitis remains inconclusive. The article discusses the potential immune-regulating role of the gut microbiome in allergic rhinitis. Further well-designed clinical trials with large-scale recruitment of allergic rhinitis patients are encouraged.

Associations between gut microbiota and chronic sinusitis: A bidirectional Mendelian randomization study

BACKGROUND

Studies have indicated a close association between dysbiosis of the gut microbiota and chronic sinusitis. However, the causal relationship between the gut microbiota and the risk of chronic sinusitis remains unclear.

METHODS

Using genome-wide association study (GWAS) data for the gut microbiota and chronic sinusitis, we conducted a two-sample Mendelian randomization (MR) study to determine the potential causal relationship between the microbiota and chronic sinusitis. We employed the inverse variance-weighted (IVW) method as the primary analytical approach to estimate the effect. Additionally, sensitivity, heterogeneity, and pleiotropy analyses were conducted to evaluate the robustness of the results. Reverse MR analysis was also applied to investigate potential reverse causality.

RESULTS

Through MR analysis, we identified 17 gut microbiota classifications that are closely associated with chronic sinusitis. However, after Bonferroni multiple correction, only class Bacilli (odds ratio: 0.785, 95% confidence interval: 0.677-0.911, p = .001, false discovery rate = 0.023) maintained a significant causal negative relationship with chronic sinusitis. Sensitivity analysis did not reveal any evidence of heterogeneity or horizontal pleiotropy. Reverse MR analysis found five gut microbiota classifications that are significantly associated with chronic sinusitis, but they were no longer significant after Bonferroni multiple correction. There was no evidence to suggest a reverse causal relationship between chronic sinusitis and class Bacilli.

CONCLUSION

Specific gut microbiota predicted by genetics exhibit a potential causal relationship with chronic sinusitis, and class Bacilli may have a protective effect on chronic sinusitis.

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

Introduction

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

Methods

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

Results

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

Conclusion

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

Gut microbiota-derived acetate attenuates lung injury induced by influenza infection via protecting airway tight junctions

BACKGROUND

Gut microbiota (GM) have been implicated as important regulators of gastrointestinal symptom which is commonly occurred along with respiratory influenza A virus (IAV) infection, suggesting the involvement of the gut-to-lung axis in a host's response to IAV. IAV primarily destroys airway epithelium tight junctions (TJs) and consequently causes acute respiratory disease syndrome. It is known that GM and their metabolism produce an anti-influenza effect, but their role in IAV-induced airway epithelial integrity remains unknown.

METHODS

A mouse model of IAV infection was established. GM were analyzed using 16S rRNA gene sequencing, and short-chain fatty acids (SCFAs) levels were measured. GM depletion and fecal microbiota transplantation (FMT) were conducted to validate the role of GM in IAV infection. A pair-feeding experiment was conducted to reveal whether IAV-induced GM dysbiosis is attributed to impaired food intake. Furthermore, human bronchial epithelial (HBE) cells were cocultured with IAV in the presence or absence of acetate. TJs function was analyzed by paracellular permeability and transepithelial electronic resistance (TEER). The mechanism of how acetate affects TJs integrity was evaluated in HBE cells transfected with G protein-coupled receptor 43 (GPR43) short hairpin RNA (shRNA).

RESULTS

IAV-infected mice exhibited lower relative abundance of acetate-producing bacteria (Bacteroides, Bifidobacterium, and Akkermansia) and decreased acetate levels in gut and serum. These changes were partly caused by a decrease in food consumption (due to anorexia). GM depletion exacerbated and FMT restored IAV-induced lung inflammatory injury. IAV infection suppressed expressions of TJs (occludin, ZO-1) leading to disrupted airway epithelial barrier function as evidenced by decreased TEER and increased permeability. Acetate pretreatment activated GPR43, partially restored IAV-induced airway epithelial barrier function, and reduced inflammatory cytokines levels (TNF-α, IL-6, and IL-1β). Such protective effects of acetate were absent in HBE cells transfected with GPR43 shRNA. Acetate and GPR43 improved TJs in an AMP-activated protein kinase (AMPK)-dependent manner.

CONCLUSION

Collectively, our results demonstrated that GM protected airway TJs by modulating GPR43-AMPK signaling in IAV-induced lung injury. Therefore, improving GM dysbiosis may be a potential therapeutic target for patients with IAV infection.

The imbalance of pulmonary Th17/Treg cells in BALB/c suckling mice infected with respiratory syncytial virus-mediated intestinal immune damage and gut microbiota changes

The immune response induced by respiratory syncytial virus (RSV) infection is closely related to changes in the composition and function of gastrointestinal microorganisms. However, the specific mechanism remains unknown and the pulmonary-intestinal axis deserves further study. In this study, the mRNA levels of ROR-γt and Foxp3 in the lung and intestine increased first and then decreased. IL-17 and IL-22 reached the maximum on the third day after infection in the lung, and on the second day after infection in the small intestine and colon, respectively. RegⅢγ in intestinal tissue reached the maximum on the third day after RSV infection. Moreover, the genus enriched in the RSV group was Aggregatibacter, and Proteus was reduced. RSV infection not only causes Th17/Treg cell imbalance in the lungs of mice but also leads to the release of excessive IL-22 from the lungs through blood circulation which binds to IL-22 receptors on the intestinal surface, inducing RegⅢγ overexpression, impaired intestinal Th17/Treg development, and altered gut microbiota composition. Our research reveals a significant link between the pulmonary and intestinal axis after RSV infection.

IMPORTANCE

RSV is the most common pathogen causing acute lower respiratory tract infections in infants and young children, but the complex interactions between the immune system and gut microbiota induced by RSV infection still requires further research. In this study, it was suggested that RSV infection in 7-day-old BALB/c suckling mice caused lung inflammation and disruption of Th17/Treg cells development, and altered the composition of gut microbiota through IL-22 induced overexpression of RegⅢγ, leading to intestinal immune injury and disruption of gut microbiota. This research reveals that IL-22 may be the link between the lung and gut. This study may provide a new insight into the intestinal symptoms caused by RSV and other respiratory viruses and the connection between the lung and gut axis, as well as new therapeutic ideas for the treatment of RSV-infected children.

Role of the intestinal microbiota in host defense against respiratory viral infections

Viral infections, including those affecting the respiratory tract, can alter the composition of the intestinal microbiota, which, in turn, can significantly influence both innate and adaptive immune responses, resulting in either enhanced pathogen clearance or exacerbation of the infection, possibly leading to inflammatory complications. A deeper understanding of the interplay between the intestinal microbiota and host immune responses in the context of respiratory viral infections (i.e. the gut-lung axis) is necessary to develop new treatments. This review highlights key mechanisms by which the intestinal microbiota, including its metabolites, can act locally or at distant organs to combat respiratory viruses. Therapeutics aimed at harnessing the microbiota to prevent and/or help treat respiratory viral infections represent a promising avenue for future investigation.

Exploring the lung-gut direction of the gut-lung axis in patients with ARDS

Acute respiratory distress syndrome (ARDS) represents a life-threatening inflammatory reaction marked by refractory hypoxaemia and pulmonary oedema. Despite advancements in treatment perspectives, ARDS still carries a high mortality rate, often due to systemic inflammatory responses leading to multiple organ dysfunction syndrome (MODS). Indeed, the deterioration and associated mortality in patients with acute lung injury (LI)/ARDS is believed to originate alongside respiratory failure mainly from the involvement of extrapulmonary organs, a consequence of the complex interaction between initial inflammatory cascades related to the primary event and ongoing mechanical ventilation-induced injury resulting in multiple organ failure (MOF) and potentially death. Even though recent research has increasingly highlighted the role of the gastrointestinal tract in this process, the pathophysiology of gut dysfunction in patients with ARDS remains mainly underexplored. This review aims to elucidate the complex interplay between lung and gut in patients with LI/ARDS. We will examine various factors, including systemic inflammation, epithelial barrier dysfunction, the effects of mechanical ventilation (MV), hypercapnia, and gut dysbiosis. Understanding these factors and their interaction may provide valuable insights into the pathophysiology of ARDS and potential therapeutic strategies to improve patient outcomes.

Effect of Enteromorpha polysaccharides on gut-lung axis in mice infected with H5N1 influenza virus

Enteromorpha polysaccharides (EPPs) have been reported to have antiviral and anti-inflammatory properties. To explore the effect of EPPs on H5N1-infected mice, mice were pretreated with EPPs before being infected with the H5N1 influenza virus intranasally. H5N1 infection resulted in body-weight loss, pulmonary and intestinal damage, and an imbalance of gut microbiota in mice. As a result of the inclusion of EPPs, the body weight of mice recovered and pathological damage to the lung and intestine was reduced. EPPs also diminished inflammation by drastically lowering the expression of proinflammatory cytokines in lungs and intestines. H5N1 infection reduced bacterial diversity, and the abundance of pathogenic bacteria such as Desulfovibrio increased. However, the beneficial bacteria Alistipes rebounded in the groups which received EPPs before the infection. The modulation of the gut-lung axis may be related to the mechanism of EPPs in antiviral and anti-inflammatory responses. EPPs have shown potential in protecting the host from the influenza A virus infection.

Spectrum of COVID-19 induced liver injury: A review report

The coronavirus disease 2019 (COVID-19) pandemic has caused changes in the global health system, causing significant setbacks in healthcare systems worldwide. This pandemic has also shown resilience, flexibility, and creativity in reacting to the tragedy. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection targets most of the respiratory tract, resulting in a severe sickness called acute respiratory distress syndrome that may be fatal in some individuals. Although the lung is the primary organ targeted by COVID-19 viruses, the clinical aspect of the disease is varied and ranges from asymptomatic to respiratory failure. However, due to an unorganized immune response and several affected mechanisms, the liver may also experience liver cell injury, ischemic liver dysfunction, and drug-induced liver injury, which can result in respiratory failure because of the immune system's disordered response and other compromised processes that can end in multisystem organ failure. Patients with liver cirrhosis or those who have impaired immune systems may be more likely than other groups to experience worse results from the SARS-CoV-2 infection. We thus intend to examine the pathogenesis, current therapy, and consequences of liver damage concerning COVID-19.

Malnutrition enteropathy in Zambian and Zimbabwean children with severe acute malnutrition: A multi-arm randomized phase II trial

Malnutrition underlies almost half of all child deaths globally. Severe Acute Malnutrition (SAM) carries unacceptable mortality, particularly if accompanied by infection or medical complications, including enteropathy. We evaluated four interventions for malnutrition enteropathy in a multi-centre phase II multi-arm trial in Zambia and Zimbabwe and completed in 2021. The purpose of this trial was to identify therapies which could be taken forward into phase III trials. Children of either sex were eligible for inclusion if aged 6-59 months and hospitalised with SAM (using WHO definitions: WLZ <-3, and/or MUAC <11.5 cm, and/or bilateral pedal oedema), with written, informed consent from the primary caregiver. We randomised 125 children hospitalised with complicated SAM to 14 days treatment with (i) bovine colostrum (n = 25), (ii) N-acetyl glucosamine (n = 24), (iii) subcutaneous teduglutide (n = 26), (iv) budesonide (n = 25) or (v) standard care only (n = 25). The primary endpoint was a composite of faecal biomarkers (myeloperoxidase, neopterin, α1-antitrypsin). Laboratory assessments, but not treatments, were blinded. Per-protocol analysis used ANCOVA, adjusted for baseline biomarker value, sex, oedema, HIV status, diarrhoea, weight-for-length Z-score, and study site, with pre-specified significance of P < 0.10. Of 143 children screened, 125 were randomised. Teduglutide reduced the primary endpoint of biomarkers of mucosal damage (effect size -0.89 (90% CI: -1.69,-0.10) P = 0.07), while colostrum (-0.58 (-1.4, 0.23) P = 0.24), N-acetyl glucosamine (-0.20 (-1.01, 0.60) P = 0.67), and budesonide (-0.50 (-1.33, 0.33) P = 0.32) had no significant effect. All interventions proved safe. This work suggests that treatment of enteropathy may be beneficial in children with complicated malnutrition. The trial was registered at ClinicalTrials.gov with the identifier NCT03716115.

Exploring the immune-inflammatory mechanism of Maxing Shigan Decoction in treating influenza virus A-induced pneumonia based on an integrated strategy of single-cell transcriptomics and systems biology

BACKGROUND

Influenza is an acute respiratory infection caused by influenza virus. Maxing Shigan Decoction (MXSGD) is a commonly used traditional Chinese medicine prescription for the prevention and treatment of influenza. However, its mechanism remains unclear.

METHOD

The mice model of influenza A virus pneumonia was established by nasal inoculation. After 3 days of intervention, the lung index was calculated, and the pathological changes of lung tissue were detected by HE staining. Firstly, transcriptomics technology was used to analyze the differential genes and important pathways in mouse lung tissue regulated by MXSGD. Then, real-time fluorescent quantitative PCR (RT-PCR) was used to verify the changes in mRNA expression in lung tissues. Finally, intestinal microbiome and intestinal metabolomics were performed to explore the effect of MXSGD on gut microbiota.

RESULTS

The lung inflammatory cell infiltration in the MXSGD group was significantly reduced (p < 0.05). The results of bioinformatics analysis for transcriptomics results show that these genes are mainly involved in inflammatory factors and inflammation-related signal pathways mediated inflammation biological modules, etc. Intestinal microbiome showed that the intestinal flora Actinobacteriota level and Desulfobacterota level increased in MXSGD group, while Planctomycetota in MXSGD group decreased. Metabolites were mainly involved in primary bile acid biosynthesis, thiamine metabolism, etc. This suggests that MXSGD has a microbial-gut-lung axis regulation effect on mice with influenza A virus pneumonia.

CONCLUSION

MXSGD may play an anti-inflammatory and immunoregulatory role by regulating intestinal microbiome and intestinal metabolic small molecules, and ultimately play a role in the treatment of influenza A virus pneumonia.

Longitudinal profiling of the microbiome at four body sites reveals core stability and individualized dynamics during health and disease

To understand the dynamic interplay between the human microbiome and host during health and disease, we analyzed the microbial composition, temporal dynamics, and associations with host multi-omics, immune, and clinical markers of microbiomes from four body sites in 86 participants over 6 years. We found that microbiome stability and individuality are body-site specific and heavily influenced by the host. The stool and oral microbiome are more stable than the skin and nasal microbiomes, possibly due to their interaction with the host and environment. We identify individual-specific and commonly shared bacterial taxa, with individualized taxa showing greater stability. Interestingly, microbiome dynamics correlate across body sites, suggesting systemic dynamics influenced by host-microbial-environment interactions. Notably, insulin-resistant individuals show altered microbial stability and associations among microbiome, molecular markers, and clinical features, suggesting their disrupted interaction in metabolic disease. Our study offers comprehensive views of multi-site microbial dynamics and their relationship with host health and disease.

Microbiota and Immunity during Respiratory Infections: Lung and Gut Affair

Bacterial and viral respiratory tract infections are the most common infectious diseases, leading to worldwide morbidity and mortality. In the past 10 years, the importance of lung microbiota emerged in the context of pulmonary diseases, although the mechanisms by which it impacts the intestinal environment have not yet been fully identified. On the contrary, gut microbial dysbiosis is associated with disease etiology or/and development in the lung. In this review, we present an overview of the lung microbiome modifications occurring during respiratory infections, namely, reduced community diversity and increased microbial burden, and of the downstream consequences on host-pathogen interaction, inflammatory signals, and cytokines production, in turn affecting the disease progression and outcome. Particularly, we focus on the role of the gut-lung bidirectional communication in shaping inflammation and immunity in this context, resuming both animal and human studies. Moreover, we discuss the challenges and possibilities related to novel microbial-based (probiotics and dietary supplementation) and microbial-targeted therapies (antibacterial monoclonal antibodies and bacteriophages), aimed to remodel the composition of resident microbial communities and restore health. Finally, we propose an outlook of some relevant questions in the field to be answered with future research, which may have translational relevance for the prevention and control of respiratory infections.

The microbiome: an integral player in immune homeostasis and inflammation in the respiratory tract

The last decade of microbiome research has highlighted its fundamental role in systemic immune and metabolic homeostasis. The microbiome plays a prominent role during gestation and into early life, when maternal lifestyle factors shape immune development of the newborn. Breast milk further shapes gut colonization, supporting the development of tolerance to commensal bacteria and harmless antigens while preventing outgrowth of pathogens. Environmental microbial and lifestyle factors that disrupt this process can dysregulate immune homeostasis, predisposing infants to atopic disease and childhood asthma. In health, the low-biomass lung microbiome, together with inhaled environmental microbial constituents, establishes the immunological set point that is necessary to maintain pulmonary immune defense. However, in disease perturbations to immunological and physiological processes allow the upper respiratory tract to act as a reservoir of pathogenic bacteria, which can colonize the diseased lung and cause severe inflammation. Studying these host-microbe interactions in respiratory diseases holds great promise to stratify patients for suitable treatment regimens and biomarker discovery to predict disease progression. Preclinical studies show that commensal gut microbes are in a constant flux of cell division and death, releasing microbial constituents, metabolic by-products, and vesicles that shape the immune system and can protect against respiratory diseases. The next major advances may come from testing and utilizing these microbial factors for clinical benefit and exploiting the predictive power of the microbiome by employing multiomics analysis approaches.

Hospital-treated infections and subsequent Parkinson's disease risk: a register-based sibling comparison study

Serious infections may result in greater risk of Parkinson's disease. However, high-quality cohort studies focusing on a potential causal role of different types and sites of infection are lacking. Gastrointestinal infections are of a particular interest due to growing evidence implicating gut dysbiosis in Parkinson's disease aetiology. This population-based cohort study used the Swedish Total Population Register to identify individuals born during 1944-77 and resident in Sweden between 1990 and 2018 (N = 3 698 319). Hospital-treated infections at ages 21-30 and 31-40 years were identified from the National Patient Register. Participants were followed to identify Parkinson's disease diagnoses from age 41 years up to December 31, 2018, when the oldest individual reached 75 years. Cox regression with a sibling comparison design to tackle familial genetic and environmental confounding was used to derive hazard ratios and 95% confidence intervals for each infection site, type, or any infections at ages 21-30 and 31-40 years. During a median follow-up of 15.4 years, 8815 unique Parkinson's disease diagnoses were accrued, with a crude rate of 17.3 (95% confidence interval 17.0, 17.7) per 100 000 person-years. After controlling for shared familial factors, hospital-treated gastrointestinal and respiratory infections between 21 and 30 years of age were associated with a greater risk of Parkinson's disease [hazard ratios 1.35 (95% confidence interval: 1.05, 1.75) and 1.45 (95% confidence interval: 1.08, 1.95), respectively]; no association was found for any infections at age 31-40 [hazard ratio 1.05 (95% confidence interval: 0.93, 1.19)]. After adjustment, no statistically significant associations were observed for other sites including genitourinary and skin. These findings suggest that hospital-treated infections of the gastrointestinal tract and lungs, both of which may have an influence on the gut microbiome, by age 30 years may be risk factors for Parkinson's disease.

Faecalibacterium duncaniae as a novel next generation probiotic against influenza

The gut-lung axis is critical during viral respiratory infections such as influenza. Gut dysbiosis during infection translates into a massive drop of microbially produced short-chain fatty acids (SCFAs). Among them, butyrate is important during influenza suggesting that microbiome-based therapeutics targeting butyrate might hold promises. The butyrate-producing bacterium Faecalibacterium duncaniae (formerly referred to as F. prausnitzii) is an emerging probiotic with several health-promoting characteristics. To investigate the potential effects of F. duncaniae on influenza outcomes, mice were gavaged with live F. duncaniae (A2-165 or I-4574 strains) five days before infection. Supplementation of F. duncaniae was associated with less severe disease, a lower pulmonary viral load, and lower levels of lung inflammation. F. duncaniae supplementation impacted on gut dysbiosis induced by infection, as assessed by 16S rRNA sequencing. Interestingly, F. duncaniae administration was associated with a recovery in levels of SCFAs (including butyrate) in infected animals. The live form of F. duncaniae was more potent that the pasteurized form in improving influenza outcomes. Lastly, F. duncaniae partially protected against secondary (systemic) bacterial infection. We conclude that F. duncaniae might serve as a novel next generation probiotic against acute viral respiratory diseases.

Human metapneumovirus respiratory infection affects both innate and adaptive intestinal immunity

Introduction

Respiratory infections are one of the leading causes of morbidity and mortality worldwide, mainly in children, immunocompromised people, and the elderly. Several respiratory viruses can induce intestinal inflammation and alterations in intestinal microbiota composition. Human metapneumovirus (HMPV) is one of the major respiratory viruses contributing to infant mortality in children under 5 years of age worldwide, and the effect of this infection at the gut level has not been studied.

Methods

Here, we evaluated the distal effects of HMPV infection on intestinal microbiota and inflammation in a murine model, analyzing several post-infection times (days 1, 3, and 5). Six to eight-week-old C57BL/6 mice were infected intranasally with HMPV, and mice inoculated with a non-infectious supernatant (Mock) were used as a control group.

Results

We did not detect HMPV viral load in the intestine, but we observed significant changes in the transcription of IFN-γ in the colon, analyzed by qPCR, at day 1 post-infection as compared to the control group. Furthermore, we analyzed the frequencies of different innate and adaptive immune cells in the colonic lamina propria, using flow cytometry. The frequency of monocyte populations was altered in the colon of HMPV -infected mice at days 1 and 3, with no significant difference from control mice at day 5 post-infection. Moreover, colonic CD8+ T cells and memory precursor effector CD8+ T cells were significantly increased in HMPV-infected mice at day 5, suggesting that HMPV may also alter intestinal adaptive immunity. Additionally, we did not find alterations in antimicrobial peptide expression, the frequency of colonic IgA+ plasma cells, and levels of fecal IgA. Some minor alterations in the fecal microbiota composition of HMPV -infected mice were detected using 16s rRNA sequencing. However, no significant differences were found in β-diversity and relative abundance at the genus level.

Discussion

To our knowledge, this is the first report describing the alterations in intestinal immunity following respiratory infection with HMPV infection. These effects do not seem to be mediated by direct viral infection in the intestinal tract. Our results indicate that HMPV can affect colonic innate and adaptive immunity but does not significantly alter the microbiota composition, and further research is required to understand the mechanisms inducing these distal effects in the intestine.

Longitudinal profiling of the microbiome at four body sites reveals core stability and individualized dynamics during health and disease

To understand dynamic interplay between the human microbiome and host during health and disease, we analyzed the microbial composition, temporal dynamics, and associations with host multi-omics, immune and clinical markers of microbiomes from four body sites in 86 participants over six years. We found that microbiome stability and individuality are body-site-specific and heavily influenced by the host. The stool and oral microbiome were more stable than the skin and nasal microbiomes, possibly due to their interaction with the host and environment. Also, we identified individual-specific and commonly shared bacterial taxa, with individualized taxa showing greater stability. Interestingly, microbiome dynamics correlated across body sites, suggesting systemic coordination influenced by host-microbial-environment interactions. Notably, insulin-resistant individuals showed altered microbial stability and associations between microbiome, molecular markers, and clinical features, suggesting their disrupted interaction in metabolic disease. Our study offers comprehensive views of multi-site microbial dynamics and their relationship with host health and disease.

Study Highlights

The stability of the human microbiome varies among individuals and body sites.Highly individualized microbial genera are more stable over time.At each of the four body sites, systematic interactions between the environment, the host and bacteria can be detected.Individuals with insulin resistance have lower microbiome stability, a more diversified skin microbiome, and significantly altered host-microbiome interactions.

Respiratory and Gut Microbiome Modification during Respiratory Syncytial Virus Infection: A Systematic Review

BACKGROUND

Respiratory syncytial virus (RSV) infection is a major cause of lower respiratory tract infection, especially in infants, and increases the risk of recurrent wheezing and asthma. Recently, researchers have proposed a possible association between respiratory diseases and microbiome alterations. However, this connection has not been fully established. Herein, we conducted a systematic literature review to evaluate the reported evidence of microbiome alterations in patients with RSV infection.

METHODS

The systematic literature review on the association between RSV and microbiome in humans was conducted by searching PubMed, EMBASE, Scopus, and CINAHL from 2012 until February 2022. The results were analyzed qualitatively, focusing on the relationship between microbiome and RSV infection with available key microbiome-related parameters.

RESULTS

In the 405 articles identified by searching databases, 12 (Respiratory tract: 9, Gut: 2, Both: 1) articles in line with the research aims were eligible for this qualitative review. The types of samples for the respiratory tract microbiome and the sequencing methods utilized varied from study to study. This review revealed that the overall microbial composition in both the respiratory tract and gut in RSV-infected patients was different from that in healthy controls. Our generated results demonstrated an increase in the abundance of Haemophilus and Streptococcus, which could contribute to the distinctive separation based on the beta diversity in the respiratory tract.

CONCLUSIONS

The respiratory tract and gut microbiome changed in patients with RSV infection. Further research with a well-organized longitudinal design is warranted to clarify the impact of microbiome alterations on disease pathogenesis.

What Makes the Gut-Lung Axis Working? From the Perspective of Microbiota and Traditional Chinese Medicine

Background

An increasing number of studies have proved that gut microbiota is involved in the occurrence and development of various lung diseases and can interact with the diseased lung. The concept of the gut-lung axis (GLA) provides a new idea for the subsequent clinical treatment of lung diseases through human microbiota. This review aims to summarize the microbiota in the lung and gut and the interaction between them from the perspectives of traditional Chinese medicine and modern medicine.

Method

We conducted a literature search by using the search terms "GLA," "gut microbiota," "spleen," and "Chinese medicine" in the databases PubMed, Web of Science, and CNKI. We then explored the mechanism of action of the gut-lung axis from traditional Chinese medicine and modern medicine.

Results

The lung and gut microbiota enable the GLA to function through immune regulation, while metabolites of the gut microbiota also play an important role. The spleen can improve the gut microbiota to achieve the regulation of the GLA.

Conclusion

Improving the gut microbiota through qi supplementation and spleen fortification provides a new approach to the clinical treatment of lung diseases by regulating the GLA. Currently, our understanding of the GLA is limited, and more research is needed to explain its working principle.

Influenza A virus infection alters the resistance profile of gut microbiota to clinically relevant antibiotics

IMPORTANCE

Influenza virus infection affects both lung and intestinal bacterial community composition. Most of the published analyses focus on the characterization of the microbiota composition changes. Here we assess functional alterations of gut microbiota such as nutrient and antibiotic resistance changes during an acute respiratory tract infection. Upon influenza A virus (IAV) infection, cecal microbiota drops accompanied by a decrease in the ability to metabolize some common nutrients under aerobic conditions. At the same time, the cecal community presents an increase in resistance against clinically relevant antibiotics, particularly cephalosporins. Functional characterization of complex communities presents an additional and necessary element of analysis that nowadays is mainly limited to taxonomic description. The consequences of these functional alterations could affect treatment strategies, especially in multimicrobial infections.

Gastrointestinal microbiota and metabolites possibly contribute to distinct pathogenicity of SARS-CoV-2 proto or its variants in rhesus monkeys

Gastrointestinal (GI) infection is evidenced with involvement in COVID-19 pathogenesis caused by SARS-CoV-2. However, the correlation between GI microbiota and the distinct pathogenicity of SARS-CoV-2 Proto and its emerging variants remains unclear. In this study, we aimed to determine if GI microbiota impacted COVID-19 pathogenesis and if the effect varied between SARS-CoV-2 Proto and its variants. We performed an integrative analysis of histopathology, microbiomics, and transcriptomics on the GI tract fragments from rhesus monkeys infected with SARS-CoV-2 proto or its variants. Based on the degree of pathological damage and microbiota profile in the GI tract, five of SARS-CoV-2 strains were classified into two distinct clusters, namely, the clusters of Alpha, Beta and Delta (ABD), and Proto and Omicron (PO). Notably, the abundance of potentially pathogenic microorganisms increased in ABD but not in the PO-infected rhesus monkeys. Specifically, the high abundance of UCG-002, UCG-005, and Treponema in ABD virus-infected animals positively correlated with interleukin, integrins, and antiviral genes. Overall, this study revealed that infection-induced alteration of GI microbiota and metabolites could increase the systemic burdens of inflammation or pathological injury in infected animals, especially in those infected with ABD viruses. Distinct GI microbiota and metabolite profiles may be responsible for the differential pathological phenotypes of PO and ABD virus-infected animals. These findings improve our understanding the roles of the GI microbiota in SARS-CoV-2 infection and provide important information for the precise prevention, control, and treatment of COVID-19.

Deciphering internal and external factors influencing intestinal junctional complexes

The intestinal barrier, an indispensable guardian of gastrointestinal health, mediates the intricate exchange between internal and external environments. Anchored by evolutionarily conserved junctional complexes, this barrier meticulously regulates paracellular permeability in essentially all living organisms. Disruptions in intestinal junctional complexes, prevalent in inflammatory bowel diseases and irritable bowel syndrome, compromise barrier integrity and often lead to the notorious "leaky gut" syndrome. Critical to the maintenance of the intestinal barrier is a finely orchestrated network of intrinsic and extrinsic factors that modulate the expression, composition, and functionality of junctional complexes. This review navigates through the composition of key junctional complex components and the common methods used to assess intestinal permeability. It also explores the critical intracellular signaling pathways that modulate these junctional components. Lastly, we delve into the complex dynamics between the junctional complexes, microbial communities, and environmental chemicals in shaping the intestinal barrier function. Comprehending this intricate interplay holds paramount importance in unraveling the pathophysiology of gastrointestinal disorders. Furthermore, it lays the foundation for the development of precise therapeutic interventions targeting barrier dysfunction.

Shotgun metagenomics and systemic targeted metabolomics highlight indole-3-propionic acid as a protective gut microbial metabolite against influenza infection

The gut-to-lung axis is critical during respiratory infections, including influenza A virus (IAV) infection. In the present study, we used high-resolution shotgun metagenomics and targeted metabolomic analysis to characterize influenza-associated changes in the composition and metabolism of the mouse gut microbiota. We observed several taxonomic-level changes on day (D)7 post-infection, including a marked reduction in the abundance of members of the Lactobacillaceae and Bifidobacteriaceae families, and an increase in the abundance of Akkermansia muciniphila. On D14, perturbation persisted in some species. Functional scale analysis of metagenomic data revealed transient changes in several metabolic pathways, particularly those leading to the production of short-chain fatty acids (SCFAs), polyamines, and tryptophan metabolites. Quantitative targeted metabolomics analysis of the serum revealed changes in specific classes of gut microbiota metabolites, including SCFAs, trimethylamine, polyamines, and indole-containing tryptophan metabolites. A marked decrease in indole-3-propionic acid (IPA) blood level was observed on D7. Changes in microbiota-associated metabolites correlated with changes in taxon abundance and disease marker levels. In particular, IPA was positively correlated with some Lactobacillaceae and Bifidobacteriaceae species (Limosilactobacillus reuteri, Lactobacillus animalis) and negatively correlated with Bacteroidales bacterium M7, viral load, and inflammation markers. IPA supplementation in diseased animals reduced viral load and lowered local (lung) and systemic inflammation. Treatment of mice with antibiotics targeting IPA-producing bacteria before infection enhanced viral load and lung inflammation, an effect inhibited by IPA supplementation. The results of this integrated metagenomic-metabolomic analysis highlighted IPA as an important contributor to influenza outcomes and a potential biomarker of disease severity.