TISSUE-SPECIFIC METABOLOMIC REPROGRAMMING DETERMINES THE DISEASE PATHOPHYSIOLOGY OF SARS-COV-2 VARIANTS IN HAMSTER MODEL (preprint)

Despite significant effort, a clear understanding of host tissue-specific responses and their implications for immunopathogenicity against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant infection has remained poorly defined. To shed light on the interaction between organs and specific SARS-CoV-2 variants, we sought to characterize the complex relationship among acute multisystem manifestations, dysbiosis of the gut microbiota, and the resulting implications for SARS-CoV-2 variant-specific immunopathogenesis in the Golden Syrian Hamster (GSH) model using multi-omics approaches. Our investigation revealed increased viremia in diverse tissues of delta-infected GSH compared to the omicron variant. Multi-omics analyses uncovered distinctive metabolic responses between the delta and omicron variants, with the former demonstrating dysregulation in synaptic transmission proteins associated with neurocognitive disorders. Additionally, delta-infected GSH exhibited an altered fecal microbiota composition, marked by increased inflammation-associated taxa and reduced commensal bacteria compared to the omicron variant. These findings underscore the SARS-CoV-2-mediated tissue insult, characterized by modified host metabolites, neurological protein dysregulation, and gut dysbiosis, highlighting the compromised gut-lung-brain axis during acute infection.

SARS-CoV-2 virus in Raw Wastewater from Student Residence Halls with concomitant 16S rRNA Bacterial Community Structure changes (preprint)

The detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in sewage is well-established, but the concomitant changes in microbial compositions during the pandemic remain insufficiently explored. This study investigates the impact of the SARS-CoV-2 virus on microbial compositions in raw sewage, utilizing 16S rRNA sequencing to analyze wastewater samples collected from six dormitories over a one-year field trial at the University of Tennessee, Knoxville. The concentration of SARS-CoV-2 RNA was assessed using a reverse transcription-quantitative polymerase chain reaction. Significant variations in bacterial composition were evident across the six dormitories, highlighting the importance of independently considering spatial differences when evaluating the raw wastewater microbiome. Positive samples for SARS-CoV-2 exhibited a prominent representation of exclusive species across all dormitories, coupled with significantly reduced bacterial diversity compared to negative samples. The correlation observed between the relative abundance of enteric pathogens and potential pathogens at sampling sites introduces a significant dimension to our understanding of COVID-19, especially the notable correlation observed in positive SARS-CoV-2 samples. Furthermore, the significant correlation in the relative abundance of potential pathogens between positive and negative SARS-CoV-2 raw sewage samples may be linked to the enduring effects of microbial dysbiosis observed during COVID-19 recovery. These findings provide valuable insights into the microbial dynamics in raw sewage during the COVID-19 pandemic.

Alterations in Vaginal Microbiota among Pregnant Women with COVID-19 (preprint)

Objective: To describe the alterations of the composition of vaginal microbiota in pregnant women with COVID-19. Design: Prospective observational single-centre study Setting: Tertiary referral hospital Participants: Pregnant women with COVID-19 Methods: The vaginal swabs were collected during the active phase of infection and consecutively, within a month after recovering from infection. In three patients, longitudinal samples before, in the course, and after infection were also obtained. The microbiome alterations were examined by 16S rRNA gene sequencing. Main outcome measures: Vaginal microbiota profiles in pregnant women with COVID-19 Results: Nineteen pregnant women with COVID-19 and 28 healthy controls who were matched according to the maternal age and gestational week were recruited. Shannon index and inverse Simpson index for cross-sectional cohort indicate that alpha diversity is significantly higher in women with COVID-19 (P=0.007 and P=0.006, respectively). There was a significantly decrease in Firmicutes (P=0.007) and Lactobacillus (P=0.019) with an increase in Bacteroidetes (P=0.024) in women with COVID-19 when compared to those of healthy controls. The higher amounts of Ureaplasma were found in women with the moderate/severe disease, compared to those of the asymptomatic/mild disease (P=0.001). Lactobacillus gasseri disappeared in women with the moderate/severe disease. Prevotella timonensis was identified only in the COVID-19 group. In longitudinal analysis, Actinobacteria was elevated, Firmicutes and Bacteroides depleted during the active phase. Conclusion: The study revealed that vaginal dysbiosis with a low abundance of Lactobacillus and an increase in Bacteroidetes is associated with COVID-19.

The relationship between gut and nasopharyngeal microbiome composition can predict the severity of COVID-19 (preprint)

BackgroundCoronavirus disease 2019 (COVID-19) is a respiratory illness caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that displays great variability in clinical phenotype. Many factors have been described to be correlated with its severity but no specific determinants of infection outcome have been identified yet, maybe due the complex pathogenic mechanisms. The microbiota could play a key role in the infection and in the progression and outcome of the disease. Hence, SARS-CoV-2 infection has been associated with nasopharyngeal and gut dysbiosis and higher abundance of opportunistic pathogens. MethodsTo identify new prognostic markers for the disease, a multicenter prospective observational cohort study was carried out in COVID-19 patients that were divided in three cohorts according to their symptomatology: mild (n=24), moderate (n=51) and severe/critical (n=31). Faecal and nasopharyngeal samples were taken and the microbiota was analysed. ResultsMicrobiota composition could be associated with the severity of the symptoms and the linear discriminant analysis identified the genera Mycoplasma and Prevotella as severity biomarkers in nasopharyngeal samples, and Allistipes, Enterococcus and Escherichia in faecal samples. Moreover, M. salivarium was defined as a unique microorganism in COVID-19 patients nasopharyngeal microbiota while P. bivia and P. timonensis were defined in faecal microbiota. A connection between faecal and nasopharyngeal microbiota in COVID-19 patients was also identified as a strong positive correlation between P. timonensis (faeces) towards P. dentalis and M. salivarium (nasopharyngeal) was found in critically ill patients. ConclusionsThis ratio could be used as a novel prognostic biomarker for severe COVID-19 patients.

SARS-CoV-2 infection is associated with intestinal permeability, systemic inflammation, and microbial dysbiosis in hospitalized COVID-19 patients (preprint)

Coronavirus disease 2019 (COVID-19) and associated severity has been linked to uncontrolled inflammation and may be associated with changes in the microbiome of mucosal sites including the gastrointestinal tract and oral cavity. These sites play an important role in host-microbe homeostasis and disruption of epithelial barrier integrity during COVID-19 may potentially lead to exacerbated inflammation and immune dysfunction. Outcomes in COVID-19 are highly disparate, ranging from asymptomatic to fatal, and the impact of microbial dysbiosis on disease severity is unclear. Here, we obtained plasma, rectal swabs, oropharyngeal swabs, and nasal swabs from 86 patients hospitalized with COVID-19 and 12 healthy volunteers. We performed 16S rRNA sequencing to characterize the microbial communities in the mucosal swabs and measured circulating cytokines, markers of gut barrier integrity, and fatty acids in the plasma samples. We compared these plasma concentrations and microbiomes between healthy volunteers and the COVID-19 patients who had survived or unfortunately died by the end of study enrollment, and between severe disease and healthy controls, as well as performed a correlation analysis between plasma variables and bacterial abundances. The rectal swabs of COVID-19 patients had reduced abundances of several commensal bacteria including Faecalibacterium prausnitsii, and an increased abundance of the opportunistic pathogens Eggerthella lenta and Hungatella hathewayi. Furthermore, the oral pathogen Scardovia wiggsiae was more abundant in the oropharyngeal swabs of COVID-19 patients who died. The abundance of both H. hathewayi and S. wiggsiae correlated with circulating inflammatory markers including IL-6, highlighting the possible role of the microbiome in COVID-19 severity, and providing potential therapeutic targets for managing COVID-19.

The Role of VSL#3 in the Treatment of Fatigue and Other Symptoms in Long Covid-19 Syndrome: a Randomized, Double-blind, Placebo-controlled Pilot Study (DELong#3) (preprint)

Long COVID, also known as Post-acute COVID-19 Syndrome (PACS), is a chronic condition affecting individuals who have recovered from acute COVID-19. It is currently estimated that around 65 million people worldwide suffer from Long COVID. It is characterized by a range of symptoms, including fatigue, exertion intolerance, neurocognitive and sensory impairment, sleep disturbance, myalgia/arthralgia, and dysautonomia. Among them fatigue has emerged as a burdensome and pervasive issue, significantly impacting the quality of life and daily functioning of Long COVID patients. Alterations in the composition of the intestinal microbiota has been reported in COVID-19 patients. Dysbiosis persists even after several months of recovery from acute SARS-CoV-2 infection. Based on this evidence, we carried out a phase 3, randomized, double-blind, placebo-controlled trial aimed at evaluating the efficacy of VSL#3, a consortium of probiotic bacterial strains, in reducing fatigue and improving various aspects of patients' well-being in patients with Long COVID syndrome.

A systematic review of gut microbiota profile in COVID-19 patients and among those who have recovered from COVID-19.

OBJECTIVES: Given the scale and persistence of coronavirus disease 2019 (COVID-19), significant attention has been devoted to understanding the relationship between human gut microbiota and COVID-19. In this systematic review we aimed to comprehensively assess the gut microbiota composition in patients infected with COVID-19 and those recovered from COVID-19 in comparison to healthy controls (HCs). METHODS: Peer-reviewed articles and preprints published up to September 1, 2022, were searched in Ovid MEDLINE, Ovid EMBASE, and SCOPUS. Observational studies reporting the gut microbiota profile in adult (≥18 years) COVID-19 patients or those recovered from COVID-19 compared to HCs were eligible for inclusion in this systematic review. The quality assessment of studies was performed using the Newcastle-Ottawa scale. RESULTS: We identified 27 studies comprising 18 studies that compared COVID-19 patients and six that compared recovered COVID-19 patients to HCs, while the other three studies compared both COVID-19 and recovered COVID-19 patients to HCs. Compared to HCs, decreased gut microbial diversity and richness and a distinctive microbial composition were reported in COVID-19 patients and recovered COVID-19 patients. In COVID-19 patients, Bacteroidetes were found to be enriched, and Firmicutes depleted. Decreased short-chain fatty acid (SCFA)-producing bacteria, such as Faecalibacterium, Ruminococcus, and Bifidobacterium, among others, were also observed in COVID-19 patients, which were not restored to normal levels in those who recovered. CONCLUSION: Gut dysbiosis was evident in COVID-19, and available data suggested that dysbiosis persisted even in recovered COVID-19 patients, with decreased Firmicutes and SCFA-producing bacteria.

Neurodegenerative and Neurodevelopmental Diseases and the Gut-Brain Axis: The Potential of Therapeutic Targeting of the Microbiome.

The human gut microbiome contains the largest number of bacteria in the body and has the potential to greatly influence metabolism, not only locally but also systemically. There is an established link between a healthy, balanced, and diverse microbiome and overall health. When the gut microbiome becomes unbalanced (dysbiosis) through dietary changes, medication use, lifestyle choices, environmental factors, and ageing, this has a profound effect on our health and is linked to many diseases, including lifestyle diseases, metabolic diseases, inflammatory diseases, and neurological diseases. While this link in humans is largely an association of dysbiosis with disease, in animal models, a causative link can be demonstrated. The link between the gut and the brain is particularly important in maintaining brain health, with a strong association between dysbiosis in the gut and neurodegenerative and neurodevelopmental diseases. This link suggests not only that the gut microbiota composition can be used to make an early diagnosis of neurodegenerative and neurodevelopmental diseases but also that modifying the gut microbiome to influence the microbiome-gut-brain axis might present a therapeutic target for diseases that have proved intractable, with the aim of altering the trajectory of neurodegenerative and neurodevelopmental diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, autism spectrum disorder, and attention-deficit hyperactivity disorder, among others. There is also a microbiome-gut-brain link to other potentially reversible neurological diseases, such as migraine, post-operative cognitive dysfunction, and long COVID, which might be considered models of therapy for neurodegenerative disease. The role of traditional methods in altering the microbiome, as well as newer, more novel treatments such as faecal microbiome transplants and photobiomodulation, are discussed.

Mycobiome analyses of critically ill COVID-19 patients suggests antifungal prophylaxis may be protective against A. fumigatus-associated mortality (preprint)

Rationale: Covid-associated pulmonary aspergillosis (CAPA) is a life-threatening complication in patients with severe COVID -19. Previously, acute respiratory distress syndrome in patients with COVID-19 has been associated with lung fungal dysbiosis, evidenced by reduced microbial diversity and Candida colonisation. Increased fungal burden in the lungs of critically ill COVID-19 patients is linked to prolonged mechanical ventilation and increased mortality. However, specific mycobiome signatures associated with severe COVID-19 in the context of survival and antifungal drug prophylaxis have not yet been determined and such knowledge could have an important impact on treatment. Objectives: To understand the composition of the respiratory mycobiome in critically ill COVID -19 patients with and without CAPA, the impact of antifungal use and its role in patient outcome. Methods: We performed a multi-national study of 39 COVID-19 patients in intensive care units (ICU) with and without CAPA. Respiratory mycobiome was profiled using ITS1 sequencing and Aspergillus fumigatus burden was further validated using qPCR. Fungal communities were investigated using alpha diversity, beta diversity, taxa prevalence and taxa abundances. Measurements and Main Results: Respiratory mycobiomes were dominated by Candida and Aspergillus. There was no significant association with corticosteroid use or CAPA diagnosis and respiratory fungal communities. Increased A. fumigatus burden was associated with mortality. The use of antifungals at ICU admission was associated with an absence of A. fumigatus. Conclusions: Our findings suggest that systemic antifungal treatment at ICU admission may be protective against A. fumigatus-associated mortality in CAPA.

Elevated HMGB1 mediates microbiome-immune axis dysregulation underlying reduced neutralization capacity in obesity-related post-acute sequelae of SARS-CoV-2 (preprint)

While obesity is a risk factor for post-acute sequelae of SARS-CoV-2 infection (PASC, "long-COVID"), the mechanism(s) underlying this phenomenon is poorly understood. To address this gap in knowledge, we performed a 6-week longitudinal study to examine immune activity and gut microbiome dysbiosis in post-acute stage patients recovering from SARS-CoV-2 infection. Self-reported symptom frequencies and blood samples were collected weekly, with plasma assessed by ELISA and Luminex for multiple biomarkers and immune cell profiling. DNA from stool samples were collected at the early stage of recovery for baseline assessments of gut microbial composition and diversity using 16S-based sequencing. Multiple regression analyses revealed obesity-related PASC linked to a proinflammatory immune profile and reduced adaptive immunity, corresponding with gut microbial dysbiosis. In particular, the high mobility group box 1 (HMGB1) protein was found to be a central mediator of this dysregulation, with its upregulated levels in plasma associated with significantly impaired viral neutralization that was exacerbated with obesity. Plasma levels of HMGB1 also negatively correlated with B-cell activating factor (BAFF), while inducing pro-inflammatory nitric oxide. These findings strongly implicate HMGB1 as a candidate biomarker of PASC, with potential applications for risk assessment and targeted therapies.

Laboratory Findings and Biomarkers in Long COVID: What Do We Know So Far? Insights Into Epidemiology, Pathogenesis, Therapeutic Perspectives and Challenges (preprint)

Long COVID (LC) encompasses a constellation of long-term symptoms experienced by at least 10% of people after the initial SARS-CoV-2 infection, and so far has affected about 65 million people. The etiology of LC remains unclear; however, many pathophysiological pathways may be involved, including viral persistence; chronic, low grade inflammatory response; immune dysregulation and defective immune response; reactivation of latent viruses; autoimmunity; persistent endothelial dysfunction and coagulopathy; gut dysbiosis; hormonal dysregulation, mitochondrial dysfunction; and autonomic nervous system dysfunction. There are no specific tests for the diagnosis of LC, and clinical features including laboratory findings and biomarkers may not specifically relate to LC. Therefore, it is of paramount importance to develop and validate biomarkers that can be employed for the prediction, diagnosis and prognosis of LC and its therapeutic response. Promising candidate biomarkers that are found in some patients are markers of systemic inflammation including acute phase proteins, cytokines and chemokines; biomarkers reflecting SARS-CoV-2 persistence, reactivation of herpesviruses and immune dysregulation; biomarkers of endotheliopathy, coagulation and fibrinolysis; microbiota alterations; diverse proteins and metabolites; hormonal and metabolic biomarkers; as well as cerebrospinal fluid biomarkers. At present, there are only two reviews summarizing relevant biomarkers; however, they do not cover the entire umbrella of current biomarkers or their link to etiopathogenetic mechanisms, and the diagnostic work-up in a comprehensive manner. Herein, we aim to appraise and synopsize the available evidence on the typical laboratory manifestations and candidate biomarkers of LC, their classification based on main LC symptomatology in the frame of the epidemiological and pathogenetic aspects of the syndrome, and furthermore assess limitations and challenges as well as potential implications in candidate therapeutic interventions.

Dysbiosis of oropharyngeal microbiome and antibiotic resistance in hospitalized COVID-19 patients.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is ongoing and multiple studies have elucidated its pathogenesis, however, the related- microbiome imbalance caused by SARS-CoV-2 is still not clear. In this study, we have comprehensively compared the microbiome composition and associated function alterations in the oropharyngeal swabs of healthy controls and coronavirus disease 2019 (COVID-19) patients with moderate or severe symptoms by metatranscriptomic sequencing. We did observe a reduced microbiome alpha-diversity but significant enrichment of opportunistic microorganisms in patients with COVID-19 compared with healthy controls, and the microbial homeostasis was rebuilt following the recovery of COVID-19 patients. Correspondingly, less functional genes in multiple biological processes and weakened metabolic pathways such as carbohydrate metabolism, energy metabolism were also observed in COVID-19 patients. We only found higher relative abundance of limited genera such as Lachnoanaerobaculum between severe patients and moderate patients while no worthy-noting microbiome diversity and function alteration were observed. Finally, we noticed that the co-occurrence of antibiotic resistance and virulence was closely related to the microbiome alteration caused by SRAS-CoV-2. Overall, our findings demonstrate that microbial dysbiosis may enhance the pathogenesis of SARS-CoV-2 and the antibiotics treatment should be critically considered.

Gut microbiome therapeutic modulation to alleviate drug-induced hepatic damage in COVID-19 patients.

Coronavirus disease 2019 (COVID-19) infection caused by the severe acute respiratory syndrome coronavirus 2 virus, its symptoms, treatment, and post-COVID-19 effects have been a major focus of research since 2020. In addition to respiratory symptoms, different clinical variants of the virus have been associated with dynamic symptoms and multiorgan diseases, including liver abnormalities. The release of cytokines by the activation of innate immune cells during viral infection and the high doses of drugs used for COVID-19 treatment are considered major drivers of liver injury in COVID-19 patients. The degree of hepatic inflammation in patients suffering from chronic liver disease and having COVID-19 could be severe and can be estimated through different liver chemistry abnormality markers. Gut microbiota influences liver chemistry through its metabolites. Gut dysbiosis during COVID-19 treatment can promote liver inflammation. Here, we highlighted the bidirectional association of liver physiology and gut microbiota (gut-liver axis) and its potential to manipulate drug-induced chemical abnormalities in the livers of COVID-19 patients.

Gut Microbiota Dysbiosis Correlates With Long COVID-19 at One-Year After Discharge.

BACKGROUND: Long coronavirus disease 2019 (COVID-19) in recovered patients (RPs) is gradually recognized by more people. However, how long it will last and the underlining mechanism remains unclear. METHODS: We conducted a prospective follow-up study to evaluate the long-term symptoms and clinical indices of RPs at one-year after discharge from Union Hospital, Wuhan, China between December 2020 to May 2021. We also performed the 16S rRNA sequencing of stool samples from RPs and healthy controls (HCs) and analyzed the correlation between the gut microbiota and long COVID-19. RESULTS: In total, 187 RPs were enrolled, among them, 84 (44.9%) RPs reported long COVID-19 symptoms at one-year after discharge. The most common long-term symptoms were cardiopulmonary symptoms, including chest tightness after activity (39/187, 20.9%), palpitations on exercise (27/187, 14.4%), sputum (21/187, 11.2%), cough (15/187, 8.0%) and chest pain (13/187, 7.0%), followed by systemic symptoms including fatigue (34/187, 18.2%) and myalgia (20/187, 10.7%), and digestive symptoms including constipation (14/187, 7.5%), anorexia (13/187, 7.0%), and diarrhea (8/187, 4.3%). Sixty-six (35.9%) RPs presented either anxiety or depression (42/187 [22.8%] and 53/187 [28.8%] respectively), and the proportion of anxiety or depression in the long symptomatic group was significantly higher than that in the asymptomatic group (41/187 [50.6%] vs. 25/187 [24.3%]). Compared with the asymptomatic group, scores of all nine 36-Item Short Form General Health Survey domains were lower in the symptomatic group (all P < 0.05). One hundred thirty RPs and 32 HCs (non-severe acute respiratory syndrome coronavirus 2 infected subjects) performed fecal sample sequencing. Compared with HCs, symptomatic RPs had obvious gut microbiota dysbiosis including significantly reduced bacterial diversities and lower relative abundance of short-chain fatty acids (SCFAs)-producing salutary symbionts such as Eubacterium_hallii_group, Subdoligranulum, Ruminococcus, Dorea, Coprococcus, and Eubacterium_ventriosum_group. Meanwhile, the relative abundance of Eubacterium_hallii_group, Subdoligranulum, and Ruminococcus showed decreasing tendencies between HCs, the asymptomatic group, and the symptomatic group. CONCLUSION: This study demonstrated the presence of long COVID-19 which correlates with gut microbiota dysbiosis in RPs at one-year after discharge, indicating gut microbiota may play an important role in long COVID-19.

Gut microbiota composition during hospitalization is associated with 60-day mortality after severe COVID-19.

BACKGROUND: Gut microbiota alterations have been reported in hospitalized COVID-19 patients, with reduced alpha diversity and altered microbiota composition related to respiratory failure. However, data regarding gut microbiota and mortality are scarce. METHODS: Rectal swabs for gut microbiota analyses were collected within 48 h after hospital admission (baseline; n = 123) and three-month post-admission (n = 50) in a subset of patients included in the Norwegian SARS-CoV2 cohort study. Samples were analysed by sequencing the 16S rRNA gene. Gut microbiota diversity and composition at baseline were assessed in relation to need for intensive care unit (ICU) admission during hospitalization. The primary objective was to investigate whether the ICU-related gut microbiota was associated with 60-day mortality. RESULTS: Gut microbiota diversity (Shannon index) at baseline was lower in COVID-19 patients requiring ICU admission during hospitalization than in those managed in general wards. A dysbiosis index representing a balance of enriched and reduced taxa in ICU compared with ward patients, including decreased abundance of butyrate-producing microbes and enrichment of a partly oral bacterial flora, was associated with need of ICU admission independent of antibiotic use, dexamethasone use, chronic pulmonary disease, PO2/FiO2 ratio, C-reactive protein, neutrophil counts or creatinine levels (adjusted p < 0.001). The ICU-related dysbiosis index at baseline correlated with systemic inflammation and was associated with 60-day mortality in univariate analyses (Hazard ratio 3.70 [2.00-8.6], p < 0.001), as well as after separate adjustment for covariates. At the three-month follow-up, the dysbiosis index remained elevated in ICU patients compared with ward patients (adjusted p = 0.007). CONCLUSIONS: Although our data should be regarded as exploratory due to low number of clinical end points, they suggest that gut microbiota alterations during hospitalization could be related to poor prognosis after severe COVID-19. Larger studies of gut involvement during COVID-19 in relation to long-term clinical outcome are warranted. Trial registration NCT04381819 . Retrospectively registered May 11, 2020.

The Pathogenesis of Gastrointestinal, Hepatic, and Pancreatic Injury in Acute and Long Coronavirus Disease 2019 Infection.

The gastrointestinal (GI) tract is targeted by severe acute respiratory syndrome coronavirus-2. The present review examines GI involvement in patients with long coronavirus disease and discusses the underlying pathophysiological mechanisms that include viral persistence, mucosal and systemic immune dysregulation, microbial dysbiosis, insulin resistance, and metabolic abnormalities. Due to the complex and potentially multifactorial nature of this syndrome, rigorous clinical definitions and pathophysiology-based therapeutic approaches are warranted.

SARS-CoV-2 infection alters the gut microbiome in diabetes patients: A cross-sectional study from Bangladesh.

Populations of different South Asian nations including Bangladesh reportedly have a high risk of developing diabetes in recent years. This study aimed to investigate the differences in the gut microbiome of COVID-19-positive participants with or without type 2 diabetes mellitus (T2DM) compared with healthy control subjects. Microbiome data of 30 participants with T2DM were compared with 22 age-, sex-, and body mass index (BMI)-matched individuals. Clinical features were recorded while fecal samples were collected aseptically from the participants. Amplicon-based (16S rRNA) metagenome analyses were employed to explore the dysbiosis of gut microbiota and its correlation with genomic and functional features in COVID-19 patients with or without T2DM. Comparing the detected bacterial genera across the sample groups, 98 unique genera were identified, of which 9 genera had unique association with COVID-19 T2DM patients. Among different bacterial groups, Shigella (25%), Bacteroides (23.45%), and Megamonas (15.90%) had higher mean relative abundances in COVID-19 patients with T2DM. An elevated gut microbiota dysbiosis in T2DM patients with COVID-19 was observed while some metabolic functional changes correlated with bidirectional microbiome dysbiosis between diabetes and non-diabetes humans gut were also found. These results further highlight the possible association of COVID-19 infection that might be linked with alteration of gut microbiome among T2DM patients.

A multicentre study reveals dysbiosis in the microbial co-infection and antimicrobial resistance gene profile in the nasopharynx of COVID-19 patients.

The impact of SARS-CoV-2 infection on the nasopharyngeal microbiome has not been well characterised. We sequenced genetic material extracted from nasopharyngeal swabs of SARS-CoV-2-positive individuals who were asymptomatic (n = 14), had mild (n = 64) or severe symptoms (n = 11), as well as from SARS-CoV-2-negative individuals who had never-been infected (n = 5) or had recovered from infection (n = 7). Using robust filters, we identified 1345 taxa with approximately 0.1% or greater read abundance. Overall, the severe cohort microbiome was least diverse. Bacterial pathogens were found in all cohorts, but fungal species identifications were rare. Few taxa were common between cohorts suggesting a limited human nasopharynx core microbiome. Genes encoding resistance mechanisms to 10 antimicrobial classes (> 25% sequence coverages, 315 genes, 63 non-redundant) were identified, with ß-lactam resistance genes near ubiquitous. Patients infected with SARS-CoV-2 (asymptomatic and mild) had a greater incidence of antibiotic resistance genes and a greater microbial burden than the SARS-CoV-2-negative individuals. This should be considered when deciding how to treat COVID-19 related bacterial infections.

Gut and airway microbiota dysbiosis and their role in COVID-19 and long-COVID.

The gut microbiota plays a crucial role in human health and disease. Gut dysbiosis is known to be associated with increased susceptibility to respiratory diseases and modifications in the immune response and homeostasis of the lungs (the so-called gut-lung axis). Furthermore, recent studies have highlighted the possible role of dysbiosis in neurological disturbances, introducing the notion of the "gut-brain axis." During the last 2 years, several studies have described the presence of gut dysbiosis during coronavirus disease 2019 (COVID-19) and its relationship with disease severity, SARS-CoV-2 gastrointestinal replication, and immune inflammation. Moreover, the possible persistence of gut dysbiosis after disease resolution may be linked to long-COVID syndrome and particularly to its neurological manifestations. We reviewed recent evidence on the association between dysbiosis and COVID-19, investigating the possible epidemiologic confounding factors like age, location, sex, sample size, the severity of disease, comorbidities, therapy, and vaccination status on gut and airway microbial dysbiosis in selected studies on both COVID-19 and long-COVID. Moreover, we analyzed the confounding factors strictly related to microbiota, specifically diet investigation and previous use of antibiotics/probiotics, and the methodology used to study the microbiota (α- and ß-diversity parameters and relative abundance tools). Of note, only a few studies focused on longitudinal analyses, especially for long-term observation in long-COVID. Lastly, there is a lack of knowledge regarding the role of microbiota transplantation and other therapeutic approaches and their possible impact on disease progression and severity. Preliminary data seem to suggest that gut and airway dysbiosis might play a role in COVID-19 and in long-COVID neurological symptoms. Indeed, the development and interpretation of these data could have important implications for future preventive and therapeutic strategies.

Gut microbiota: A new insight into lung diseases.

The human gut microbiota is a complex ecosystem involved in the metabolism, immunity, and health of the host. The microbiome plays a key role in the development of the host's innate and adaptive immune system, while the immune system orchestrates the maintenance of host-microbe symbiosis. Lung diseases are usually accompanied by dysbiosis of the intestinal flora and an immune-inflammatory response. The intestinal flora and its metabolites are directly or indirectly involved in the immune regulation of the host in lung disease. However, the exact mechanism of action of the gut-lung axis crosstalk remains unclear. This review is aimed to summarize the latest advances in gut microbiota and their metabolites in typical lung diseases, such as pulmonary hypertension, COPD, and lung cancer. Especially COVID-19, a problem troubling the world, is also discussed in it. Moreover, it is concentrated on the action mechanisms between the identified gut microbiota or their metabolites and the specific lung diseases, and on the link among the gut microbiota, its metabolites, and immune regulation, which could be used as a breakthrough to find new mechanisms and targets for some diseases without specific therapeutic drugs in clinic. It is also discussed a new therapeutic tool "drug-bacterial interaction" and the potential of therapeutic applications in clinic. This review would provide a clear direction for future research on gut microbiota and lung diseases, and propose a new therapeutic strategy targeting "drug-bacterial interaction" in clinic.