Neuropsychiatric Ramifications of COVID-19: Short-Chain Fatty Acid Deficiency and Disturbance of Microbiota-Gut-Brain Axis Signaling.

COVID-19-associated neuropsychiatric complications are soaring. There is an urgent need to understand the link between COVID-19 and neuropsychiatric disorders. To that end, this article addresses the premise that SARS-CoV-2 infection results in gut dysbiosis and an altered microbiota-gut-brain (MGB) axis that in turn contributes to the neuropsychiatric ramifications of COVID-19. Altered MGB axis activity has been implicated independently as a risk of neuropsychiatric disorders. A review of the changes in gut microbiota composition in individual psychiatric and neurological disorders and gut microbiota in COVID-19 patients revealed a shared "microbial signature" characterized by a lower microbial diversity and richness and a decrease in health-promoting anti-inflammatory commensal bacteria accompanied by an increase in opportunistic proinflammatory pathogens. Notably, there was a decrease in short-chain fatty acid (SCFA) producing bacteria. SCFAs are key bioactive microbial metabolites with anti-inflammatory functions and have been recognized as a critical signaling pathway in the MGB axis. SCFA deficiency is associated with brain inflammation, considered a cardinal feature of neuropsychiatric disorders. The link between SARS-CoV-2 infection, gut dysbiosis, and altered MGB axis is further supported by COVID-19-associated gastrointestinal symptoms, a high number of SARS-CoV-2 receptors, angiotensin-cleaving enzyme-2 (ACE-2) in the gut, and viral presence in the fecal matter. The binding of SARS-CoV-2 to the receptor results in ACE-2 deficiency that leads to decreased transport of vital dietary components, gut dysbiosis, proinflammatory gut status, increased permeability of the gut-blood barrier (GBB), and systemic inflammation. More clinical research is needed to substantiate further the linkages described above and evaluate the potential significance of gut microbiota as a diagnostic tool. Meanwhile, it is prudent to propose changes in dietary recommendations in favor of a high fiber diet or supplementation with SCFAs or probiotics to prevent or alleviate the neuropsychiatric ramifications of COVID-19.

Intestinal Flora: A Pivotal Role in Investigation of Traditional Chinese Medicine.

Intestinal flora is essential for maintaining host health and plays a unique role in transforming Traditional Chinese Medicine (TCM). TCM, as a bodyguard, has saved countless lives and maintained human health in the long history, especially in this COVID-19 pandemic. Pains of diseases have been removed from the effective TCM therapy, such as TCM preparation, moxibustion, and acupuncture. With the development of life science and technology, the wisdom and foresight of TCM has been more displayed. Furthermore, TCM has been also inherited and developed in innovation to better realize the modernization and globalization. Nowadays, intestinal flora transforming TCM and TCM targeted intestinal flora treating diseases have been important findings in life science. More and more TCM researches showed the significance of intestinal flora. Intestinal flora is also a way to study TCM to elucidate the profound theory of TCM. Processing, compatibility, and properties of TCM are well demonstrated by intestinal flora. Thus, it is no doubt that intestinal flora is a core in TCM study. The interaction between intestinal flora and TCM is so crucial for host health. Therefore, it is necessary to sum up the latest results in time. This paper systematically depicted the profile of TCM and the importance of intestinal flora in host. What is more, we comprehensively summarized and discussed the latest progress of the interplay between TCM and intestinal flora to better reveal the core connotation of TCM.

The African Network for Improved Diagnostics, Epidemiology and Management of common infectious Agents.

BACKGROUND: In sub-Saharan Africa, acute respiratory infections (ARI), acute gastrointestinal infections (GI) and acute febrile disease of unknown cause (AFDUC) have a large disease burden, especially among children, while respective aetiologies often remain unresolved. The need for robust infectious disease surveillance to detect emerging pathogens along with common human pathogens has been highlighted by the ongoing novel coronavirus disease 2019 (COVID-19) pandemic. The African Network for Improved Diagnostics, Epidemiology and Management of Common Infectious Agents (ANDEMIA) is a sentinel surveillance study on the aetiology and clinical characteristics of ARI, GI and AFDUC in sub-Saharan Africa. METHODS: ANDEMIA includes 12 urban and rural health care facilities in four African countries (Côte d'Ivoire, Burkina Faso, Democratic Republic of the Congo and Republic of South Africa). It was piloted in 2018 in Côte d'Ivoire and the initial phase will run from 2019 to 2021. Case definitions for ARI, GI and AFDUC were established, as well as syndrome-specific sampling algorithms including the collection of blood, naso- and oropharyngeal swabs and stool. Samples are tested using comprehensive diagnostic protocols, ranging from classic bacteriology and antimicrobial resistance screening to multiplex real-time polymerase chain reaction (PCR) systems and High Throughput Sequencing. In March 2020, PCR testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and analysis of full genomic information was included in the study. Standardised questionnaires collect relevant clinical, demographic, socio-economic and behavioural data for epidemiologic analyses. Controls are enrolled over a 12-month period for a nested case-control study. Data will be assessed descriptively and aetiologies will be evaluated using a latent class analysis among cases. Among cases and controls, an integrated analytic approach using logistic regression and Bayesian estimation will be employed to improve the assessment of aetiology and associated risk factors. DISCUSSION: ANDEMIA aims to expand our understanding of ARI, GI and AFDUC aetiologies in sub-Saharan Africa using a comprehensive laboratory diagnostics strategy. It will foster early detection of emerging threats and continued monitoring of important common pathogens. The network collaboration will be strengthened and site diagnostic capacities will be reinforced to improve quality management and patient care.

Case report: histopathology and molecular pathology analysis on enteric tissue of a COVID-19 patient.

AIMS: Patients with COVID-19 can also have enteric symptoms. Here we analyzed the histopathology of intestinal detachment tissue from a patient with COVID-19. METHODS: The enteric tissue was examined by hematoxylin & eosin stain, PAS (Periodic acid-Schiff) staining, Gram staining, Ziehl-Neelsen stain and Grocott's Methenamine Silver (GMS) Stain. The distribution of CD3, CD4, CK20 and CD68, cytomegalovirus (CMV) and Herpes Simplex Virus (HSV) antigen were determined by immunohistochemistry. In situ hybridization (ISH) of SARS-CoV-2 and Epstein-Barr virus-encoded small RNA (EBER) were also performed. RESULTS: We observed mucosal epithelium shedding, intestinal mucosal erosion, focal inflammatory necrosis with hemorrhage, massive neutrophil infiltration, macrophage proliferation accompanied by minor lymphocyte infiltration. Fungal spores and gram positive cocci but not mycobacteria tuberculosis were identified. Immunohistochemistry staining showed abundant CD68+ macrophages but few lymphocytes infiltration. HSV, CMV and EBV were negative. ISH of SARS-CoV-2 RNA showed positive signal which mostly overlapped with CD68 positivity. CONCLUSIONS: The in situ detection of SARS-CoV-2 RNA in intestinal macrophages implicates a possible route for gastrointestinal infection. Further study is needed to further characterize the susceptibility of enteric cells to SARS-CoV-2 infection.

Gastrointestinal disturbance and effect of fecal microbiota transplantation in discharged COVID-19 patients.

BACKGROUND: To investigate the potential beneficial effect of fecal microbiota transplantation (FMT) on gastrointestinal symptoms, gut dysbiosis and immune status in discharged COVID-19 patients. CASE PRESENTATION: A total of 11 COVID-19 patients were recruited in April, 2020, about one month on average after they were discharged from the hospital. All subjects received FMT for 4 consecutive days by oral capsule administrations with 10 capsules for each day. In total, 5 out of 11 patients reported to be suffered from gastrointestinal symptoms, which were improved after FMT. After FMT, alterations of B cells were observed, which was characterized as decreased naive B cell (P = 0.012) and increased memory B cells (P = 0.001) and non-switched B cells (P = 0.012).The microbial community richness indicated by operational taxonomic units number, observed species and Chao1 estimator was marginally increased after FMT. Gut microbiome composition of discharged COVID-19 patients differed from that of the general population at both phylum and genera level, which was characterized with a lower proportion of Firmicutes (41.0%) and Actinobacteria (4.0%), higher proportion of Bacteroidetes (42.9%) and Proteobacteria (9.2%). FMT can partially restore the gut dysbiosis by increasing the relative abundance of Actinobacteria (15.0%) and reducing Proteobacteria (2.8%) at the phylum level. At the genera level, Bifidobacterium and Faecalibacterium had significantly increased after FMT. CONCLUSIONS: After FMT, altered peripheral lymphocyte subset, restored gut microbiota and alleviated gastrointestinal disorders were observe, suggesting that FMT may serve as a potential therapeutic and rehabilitative intervention for the COVID-19.

Coronavirus Disease (COVID-19) Caused by (SARS-CoV-2) Infections: A Real Challenge for Human Gut Microbiota.

The current COVID-19 pandemic is a great challenge for worldwide researchers in the human microbiota area because the mechanisms and long-term effects of the infection at the GI level are not yet deeply understood. In the current review, scientific literature including original research articles, clinical studies, epidemiological reports, and review-type articles concerning human intestinal infection with SARS-CoV-2 and the possible consequences on the microbiota were reviewed. Moreover, the following aspects pertaining to COVID-19 have also been discussed: transmission, resistance in the human body, the impact of nutritional status in relation to the intestinal microbiota, and the impact of comorbid metabolic disorders such as inflammatory bowel disease (IBS), obesity, and type two diabetes (T2D). The articles investigated show that health, age, and nutritional status are associated with specific communities of bacterial species in the gut, which could influence the clinical course of COVID-19 infection. Fecal microbiota alterations were associated with fecal concentrations of SARS-CoV-2 and COVID-19 severity. Patients suffering from metabolic and gastrointestinal (GI) disorders are thought to be at a moderate-to-high risk of infection with SARS-CoV-2, indicating the direct implication of gut dysbiosis in COVID-19 severity. However, additional efforts are required to identify the initial GI symptoms of COVID-19 for possible early intervention.

COVID-19 - gastrointestinal and gut microbiota-related aspects.

OBJECTIVE: The aim of this review paper was to discuss the gut microbiota-related aspects of COVID-19 patients. We presented the faecal-oral transmission of SARS-CoV-2, gut microbiota imbalance, and fecal microbiota transplantation as a hidden source of this virus. MATERIALS AND METHODS: We analyzed the available literature (PubMed, Embase, Google Scholar databases) regarding COVID-19 and gut microbiota related aspects. RESULTS: The gastrointestinal symptoms, such as nausea, vomiting, diarrhea, abdominal discomfort/pain, may occur in these patients. Notably, these symptoms may contribute to the severity of COVID-19. Recent several studies have revealed a new SARS-CoV-2 transmission possibility, opening a fresh view on COVID-19. It is observed the possibility of SARS-CoV-2 transmission via faecal-oral route. Fecal microbiota transplantation may be a hidden source of SARS-CoV-2. Additionally, the pharmacological treatment of COVID-19 and other factors may significantly alter the composition of gut microbiota. Among others, loss of bacterial diversity, the decrease of commensal microbes as well as the increase of opportunistic pathogens are observed. CONCLUSIONS: The alterations of gut microbiota in COVID-19 patients consequently may lead to the development of gut dysbiosis-related diseases even after recovery from COVID-19. Therefore, it is recommended to screen stool samples taken from recovered patients at least 35 days after clearance of virus from respiratory tract. Before 35 days period, SARS-CoV-2 may still be detected in feces. It is also recommended to screen the composition as well as the activity of gut microbiota to assess its balance. In the case of gut dysbiosis, there should be introduced an appropriate method of its modulation. Additionally, all the fecal samples which are prepared for fecal microbiota transplantation should be tested for SARS-CoV-2 to provide protection for its recipients.

Gastrointestinal symptoms associated with COVID-19: impact on the gut microbiome.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the greatest worldwide pandemic since the 1918 flu. The consequences of the coronavirus disease 2019 (COVID-19) are devastating and represent the current major public health issue across the globe. At the onset, SARS-CoV-2 primarily attacks the respiratory system as it represents the main point of entry in the host, but it also can affect multiple organs. Although most of the patients do not present symptoms or are mildly symptomatic, some people infected with SARS-CoV-2 that experience more severe multiorgan dysfunction. The severity of COVID-19 is typically combined with a set of comorbidities such as hypertension, diabetes, obesity, and/or advanced age that seriously exacerbates the consequences of the infection. Also, SARS-CoV-2 can cause gastrointestinal symptoms, such as vomiting, diarrhea, or abdominal pain during the early phases of the disease. Intestinal dysfunction induces changes in intestinal microbes, and an increase in inflammatory cytokines. Thus, diagnosing gastrointestinal symptoms that precede respiratory problems during COVID-19 may be necessary for improved early detection and treatment. Uncovering the composition of the microbiota and its metabolic products in the context of COVID-19 can help determine novel biomarkers of the disease and help identify new therapeutic targets. Elucidating changes to the microbiome as reliable biomarkers in the context of COVID-19 represent an overlooked piece of the disease puzzle and requires further investigation.

Temporal Correlation Between Neurological and Gastrointestinal Symptoms of SARS-CoV-2.

Severe Acute Respiratory Syndrome Coronavirus-2 (SAR-CoV-2) has been shown to invade brain tissue. Based on the evolutionary similarity with SARS-CoV, researchers propose that SARS-CoV-2 can invade the olfactory bulb and gastrointestinal (GI) system through angiotensin-converting enzyme 2. However, how SARS-CoV-2 causes neurological or GI symptoms is not clear. Many suggested intestinal and neural inflammations, caused by viral invasion, as the most likely reason for the GI and neurological symptoms; however, the patients with coronavirus disease 2019 (COVID-19) without neurological or GI symptoms indicate that this is not the case. The gut-brain axis could explain the reason for why some with COVID-19 do not have these symptoms. COVID-19 patients mostly show respiratory distress first, then diarrhea, anorexia, stroke, or loss of consciousness comes into view. Obviously, GI invasion is a mechanical process that begins with oral invasion and, therefore, most probably exists before the brain invasion, as indicated in case reports. However, when the GI tract is invaded, the virus may enter the central nervous system through vascular and lymphatic systems or the vagal nerve. SARS-CoV-2 can infect leukocytes and migrate with them into the brain, or the viral particles can be directly transported across the blood-brain barrier to the brain. Also, more recent research has revealed that SARS-CoV-2 can invade the peripheral lymphatic vessels connecting with the glymphatic system of the brain. The temporal correlation between neurological and gastrointestinal symptoms suggests the lymph vessels around the GI tract, the vascular system, or the gut-brain axis (enteric nervous system) as the most likely entry route for SARS-CoV-2 to the brain.