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

Major alteration of Lung Microbiome and the Host Reaction in critically ill COVID-19 Patients with high viral load

Background

Patients with COVID-19 under invasive mechanical ventilation are at higher risk of developing ventilator-associated pneumonia (VAP), associated with increased healthcare costs, and unfavorable prognosis. The underlying mechanisms of this phenomenon have not been thoroughly dissected. Therefore, this study attempted to bridge this gap by performing a lung microbiota analysis and evaluating the host immune responses that could drive the development of VAP.

Materials and methods

In this prospective cohort study, mechanically ventilated patients with confirmed SARS-CoV-2 infection were enrolled. Nasal swabs (NS), endotracheal aspirates (ETA), and blood samples were collected initially within 12 hours of intubation and again at 72 hours post-intubation. Plasma samples underwent cytokine and metabolomic analyses, while NS and ETA samples were sequenced for lung microbiome examination. The cohort was categorized based on the development of VAP. Data analysis was conducted using RStudio version 4.3.1.

Results

In a study of 36 COVID-19 patients on mechanical ventilation, significant differences were found in the nasal and pulmonary microbiome, notably in Staphylococcus and Enterobacteriaceae, linked to VAP. Patients with VAP showed a higher SARS-CoV-2 viral load, elevated neutralizing antibodies, and reduced inflammatory cytokines, including IFN-δ, IL-1β, IL-12p70, IL-18, IL-6, TNF-α, and CCL4. Metabolomic analysis revealed changes in 22 metabolites in non-VAP patients and 27 in VAP patients, highlighting D-Maltose-Lactose, Histidinyl-Glycine, and various phosphatidylcholines, indicating a metabolic predisposition to VAP.

Conclusions

This study reveals a critical link between respiratory microbiome alterations and ventilator-associated pneumonia in COVID-19 patients, with elevated SARS-CoV-2 levels and metabolic changes, providing novel insights into the underlying mechanisms of VAP with potential management and prevention implications.

Bibliometric analysis of intestinal microbiota and lung diseases

Background

Increasing evidence suggests a close association between the intestinal microbiome and the respiratory system, drawing attention to studying the gut-lung axis. This research employs bibliometric methods to conduct a visual analysis of literature in the field of intestinal microbiota and lung diseases over the past two decades. It offers scientific foundations for research directions and critical issues in this field.

Methods

We retrieved all articles on intestinal microbiota and lung diseases from the SCI-Expanded of WoSCC on October 25, 2023. The analysis included original articles and reviews published in English from 2011 to 2023. We utilized Python, VOSviewer, and CiteSpace to analyze the retrieved data visually.

Results

A total of 794 publications were analyzed. China ranked first in the number of publications, while the United States had the highest citations and H-index. Jian Wang was the most prolific author. Zhejiang University was the institution with the highest number of publications. Frontiers in Microbiology was the journal with the most publications. Author keywords appearing more than 100 times included "intestinal microbiota/microbiome", "microbiota/microbiome", and "gut-lung axis".

Conclusion

The correlation and underlying mechanisms between intestinal microbiota and lung diseases, including asthma, COPD, lung cancer, and respiratory infections, remain hot topics in research. However, understanding the mechanisms involving the gut-lung axis is still in its infancy and requires further elucidation.

Gut Microbiome-Based Therapeutics in Critically Ill Adult Patients-A Narrative Review

The gut microbiota plays a crucial role in the human microenvironment. Dysbiosis of the gut microbiota is a common pathophysiological phenomenon in critically ill patients. Therefore, utilizing intestinal microbiota to prevent complications and improve the prognosis of critically ill patients is a possible therapeutic direction. The gut microbiome-based therapeutics approach focuses on improving intestinal microbiota homeostasis by modulating its diversity, or treating critical illness by altering the metabolites of intestinal microbiota. There is growing evidence that fecal microbiota transplantation (FMT), selective digestive decontamination (SDD), and microbiota-derived therapies are all effective treatments for critical illness. However, different treatments are appropriate for different conditions, and more evidence is needed to support the selection of optimal gut microbiota-related treatments for different diseases. This narrative review summarizes the curative effects and limitations of microbiome-based therapeutics in different critically ill adult patients, aiming to provide possible directions for gut microbiome-based therapeutics for critically ill patients such as ventilator-associated pneumonia, sepsis, acute respiratory distress syndrome, and COVID-19, etc.

The potential of dietary fiber in building immunity against gastrointestinal and respiratory disorders

The numerous health benefits of dietary fibers (DFs) justify their inclusion in human diets and biomedical products. Given the short- and long-term human impacts of the COVID-19 virus on human health, the potential of DFs in building immunity against gastrointestinal and respiratory disorders is currently receiving high attention. This paper reviews the physicochemical properties of DFs, together with their immune functions and effects on the gastrointestinal tract and respiratory system mainly based on research in the last ten years. Possible modes of action of DFs in promoting health, especially building immunity, are explored. We seek to highlight the importance of understanding the exact physical and chemical characteristics and molecular behaviors of DFs in providing specific immune function. This review provides a perspective beyond the existing recognition of DFs' positive effects on human health, and offers a theoretical framework for the development of special DFs components and their application in functional foods and other therapeutic products against gastrointestinal and respiratory disorders. DFs enhance immunity from gastrointestinal and respiratory diseases to promote host health.

Unravelling the gut-lung axis: insights into microbiome interactions and Traditional Indian Medicine's perspective on optimal health

The microbiome of the human gut is a complex assemblage of microorganisms that are in a symbiotic relationship with one another and profoundly influence every aspect of human health. According to converging evidence, the human gut is a nodal point for the physiological performance matrixes of the vital organs on several axes (i.e. gut-brain, gut-lung, etc). As a result of COVID-19, the importance of gut-lung dysbiosis (balance or imbalance) has been realised. In view of this, it is of utmost importance to develop a comprehensive understanding of the microbiome, as well as its dysbiosis. In this review, we provide an overview of the gut-lung axial microbiome and its importance in maintaining optimal health. Human populations have successfully adapted to geophysical conditions through traditional dietary practices from around the world. In this context, a section has been devoted to the traditional Indian system of medicine and its theories and practices regarding the maintenance of optimally customized gut health.

Gut Microbiota Dysbiosis in COVID-19: Modulation and Approaches for Prevention and Therapy

Inflammation and oxidative stress are critical underlying mechanisms associated with COVID-19 that contribute to the complications and clinical deterioration of patients. Additionally, COVID-19 has the potential to alter the composition of patients' gut microbiota, characterized by a decreased abundance of bacteria with probiotic effects. Interestingly, certain strains of these bacteria produce metabolites that can target the S protein of other coronaviruses, thereby preventing their transmission and harmful effects. At the same time, the presence of gut dysbiosis can exacerbate inflammation and oxidative stress, creating a vicious cycle that perpetuates the disease. Furthermore, it is widely recognized that the gut microbiota can metabolize various foods and drugs, producing by-products that may have either beneficial or detrimental effects. In this regard, a decrease in short-chain fatty acid (SCFA), such as acetate, propionate, and butyrate, can influence the overall inflammatory and oxidative state, affecting the prevention, treatment, or worsening of COVID-19. This review aims to explore the current evidence regarding gut dysbiosis in patients with COVID-19, its association with inflammation and oxidative stress, the molecular mechanisms involved, and the potential of gut microbiota modulation in preventing and treating SARS-CoV-2 infection. Given that gut microbiota has demonstrated high adaptability, exploring ways and strategies to maintain good intestinal health, as well as an appropriate diversity and composition of the gut microbiome, becomes crucial in the battle against COVID-19.

Microbiota Profile of the Nasal Cavity According to Lifestyles in Healthy Adults in Santiago, Chile

BACKGROUND

The respiratory microbiome is dynamic, varying between anatomical niches, and it is affected by various host and environmental factors, one of which is lifestyle. Few studies have characterized the upper respiratory tract microbiome profile according to lifestyle. We explored the association between lifestyles and microbiota profiles in the upper respiratory tract of healthy adults.

METHODS

We analyzed nasal samples from 110 healthy adults who were living in Santiago, Chile, using 16S ribosomal RNA gene-sequencing methods. Volunteers completed a structured questionnaire about lifestyle.

RESULTS

The composition and abundance of taxonomic groups varied across lifestyle attributes. Additionally, multivariate models suggested that alpha diversity varied in the function of physical activity, nutritional status, smoking, and the interaction between nutritional status and smoking, although the significant impact of those variables varied between women and men. Although physical activity and nutritional status were significantly associated with all indexes of alpha diversity among women, the diversity of microbiota among men was associated with smoking and the interaction between nutritional status and smoking.

CONCLUSIONS

The alpha diversity of nasal microbiota is associated with lifestyle attributes, but these associations depend on sex and nutritional status. Our results suggest that future studies of the airway microbiome may provide a better resolution if data are stratified for differences in sex and nutritional status.

Alterations of the gut microbiota in coronavirus disease 2019 and its therapeutic potential

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a serious threat to global health. SARS-CoV-2 infects host cells primarily by binding to angiotensin-converting enzyme 2, which is coexpressed in alveolar type 2 cells and gut epithelial cells. It is known that COVID-19 often presents with gastrointestinal symptoms and gut dysbiosis, mainly characterized by an increase in opportunistic pathogens and a decrease in beneficial commensal bacteria. In recent years, multiple studies have comprehensively explored gut microbiota alterations in COVID-19 and highlighted the clinical correlation between dysbiosis and COVID-19. SARS-CoV-2 causes gastrointestinal infections and dysbiosis mainly through fecal-oral transmission and the circulatory and immune pathways. Studies have shown that the gut microbiota and its metabolites can regulate the immune response and modulate antiviral effects. In addition, the gut microbiota is closely related to gastrointestinal symptoms, such as diarrhea, a common gastrointestinal symptom among COVID-19. Therefore, the contribution of the gut microbiota in COVID-19 should not be overlooked. Strategies targeting the gut microbiota via probiotics, prebiotics and fecal microbiota transplantation should be considered to treat this patient population in the future. However, the specific alterations and mechanisms as well as the contributions of gut microbiota in COVID-19 should be urgently further explored.

Nutraceuticals and COVID-19: A mechanistic approach toward attenuating the disease complications

Nutraceuticals have emerged as potential compounds to attenuate the COVID-19 complications. Precisely, these food additives strengthen the overall COVID treatment and enhance the immunity of a person. Such compounds have been used at a large scale, in almost every household due to their better affordability and easy access. Therefore, current research is focused on developing newer advanced formulations from potential drug candidates including nutraceuticals with desirable properties viz, affordability, ease of availability, ease of administration, stability under room temperature, and potentially longer shelf-lives. As such, various nutraceutical-based products such as compounds could be promising agents for effectively managing COVID-19 symptoms and complications. Most importantly, regular consumption of such nutraceuticals has been shown to boost the immune system and prevent viral infections. Nutraceuticals such as vitamins, amino acids, flavonoids like curcumin, and probiotics have been studied for their role in the prevention of COVID-19 symptoms such as fever, pain, malaise, and dry cough. In this review, we have critically reviewed the potential of various nutraceutical-based therapeutics for the management of COVID-19. We searched the information relevant to our topic from search engines such as PubMed and Scopus using COVID-19, nutraceuticals, probiotics, and vitamins as a keyword. Any scientific literature published in a language other than English was excluded. PRACTICAL APPLICATIONS: Nutraceuticals possess both nutritional values and medicinal properties. They can aid in the prevention and treatment of diseases, as well as promote physical health and the immune system, normalizing body functions, and improving longevity. Recently, nutraceuticals such as probiotics, vitamins, polyunsaturated fatty acids, trace minerals, and medicinal plants have attracted considerable attention and are widely regarded as potential alternatives to current therapeutic options for the effective management of various diseases, including COVID-19.

Interactions between Dietary Micronutrients, Composition of the Microbiome and Efficacy of Immunotherapy in Cancer Patients

The effectiveness of immunotherapy in cancer patients depends on the activity of the host's immune system. The intestinal microbiome is a proven immune system modulator, which plays an important role in the development of many cancers and may affect the effectiveness of anti-cancer therapy. The richness of certain bacteria in the gut microbiome (e.g., Bifidobacterium spp., Akkermanisa muciniphila and Enterococcus hire) improves anti-tumor specific immunity and the response to anti-PD-1 or anti-PD-L1 immunotherapy by activating antigen-presenting cells and cytotoxic T cells within the tumor. Moreover, micronutrients affect directly the activities of the immune system or regulate their function by influencing the composition of the microbiome. Therefore, micronutrients can significantly influence the effectiveness of immunotherapy and the development of immunorelated adverse events. In this review, we describe the relationship between the supply of microelements and the abundance of various bacteria in the intestinal microbiome and the effectiveness of immunotherapy in cancer patients. We also point to the function of the immune system in the case of shifts in the composition of the microbiome and disturbances in the supply of microelements. This may in the future become a therapeutic target supporting the effects of immunotherapy in cancer patients.

The Role of Astaxanthin as a Nutraceutical in Health and Age-Related Conditions

The current review provides an up-to-date analysis of scientific data on astaxanthin (ASX) sources and experimental studies on its health benefits as a potent antioxidant in the aging process. ASX is a liposoluble carotenoid nutrient and reddish-orange pigment, naturally synthesized by numerous microalgae, yeasts, and bacteria as secondary metabolites. Provides a reddish hue to redfish and shellfish flesh that feed on ASX-producing microorganisms. The microalga Haematococcus pluvialis is the most important source for its industrial bioproduction. Due to its strong antioxidant properties, numerous investigations reported that natural ASX is a more significant antioxidant agent than other antioxidants, such as vitamin C, vitamin E, and β-carotene. Furthermore, several data show that ASX possesses important nutraceutical applications and health benefits, especially in healthy aging processes. However, further studies are needed for a deeper understanding of the potential mechanisms through which ASX could lead to its effective role in the healthy aging process, such as supporting brain health and skin homeostasis. This review highlights the current investigations on the effective role of ASX in oxidative stress, aging mechanisms, skin physiology, and central nervous system functioning, and shows the potential clinical implications related to its consumption.

Natural Compounds and Products from an Anti-Aging Perspective

Aging is a very complex process that is accompanied by a degenerative impairment in many of the major functions of the human body over time. This inevitable process is influenced by hereditary factors, lifestyle, and environmental influences such as xenobiotic pollution, infectious agents, UV radiation, diet-borne toxins, and so on. Many external and internal signs and symptoms are related with the aging process and senescence, including skin dryness and wrinkles, atherosclerosis, diabetes, neurodegenerative disorders, cancer, etc. Oxidative stress, a consequence of the imbalance between pro- and antioxidants, is one of the main provoking factors causing aging-related damages and concerns, due to the generation of highly reactive byproducts such as reactive oxygen and nitrogen species during the metabolism, which result in cellular damage and apoptosis. Antioxidants can prevent these processes and extend healthy longevity due to the ability to inhibit the formation of free radicals or interrupt their propagation, thereby lowering the level of oxidative stress. This review focuses on supporting the antioxidant system of the organism by balancing the diet through the consumption of the necessary amount of natural ingredients, including vitamins, minerals, polyunsaturated fatty acids (PUFA), essential amino acids, probiotics, plants' fibers, nutritional supplements, polyphenols, some phytoextracts, and drinking water.

Proposition of a New POLA Index to Assess the Immunomodulatory Properties of the Diet and Its Relationship with the Gut Microbiota, Using the Example of the Incidence of COVID-19 in a Group of People without Comorbidities

A rise in the incidence of infections with severe acute respiratory syndrome coronavirus 2 has sparked the search for protective strategies against the new pathogen. It is known that individual food components can interact with different immune cells, modulating the immune response of the body. The aim of this study was to develop an index assessing the immunomodulatory potential of diet (POLA index) and to test its utility for the prediction of coronavirus disease 2019 (COVID-19) in a group of healthy young people following a traditional or vegetarian diet. Data on body composition, anthropometric measurements, physical activity, dietary intake, and gut microbiota were obtained from 95 adults (mean age, 34.66 ± 5.76 years). There was a strong correlation between the dietary inflammatory index and the POLA index (r = 0.90; p < 0.0001). Based on Cohen’s kappa statistic, there was a good agreement in qualitative interpretation between the two indices (kappa = 0.61; p < 0.0001). People on a diet with beneficial immunomodulatory effects had a lower risk of COVID-19 of approximately 80%, as compared with those on a diet with highly unbeneficial immunomodulatory effects. In daily practice, the POLA index might serve as a useful tool for dietitians to identify individuals whose diet is deficient in ingredients for optimal immune system function and change their dietary behavior to ensure optimal immune function that reduces the risk of infection.

Are Nutraceuticals Effective in COVID-19 and Post-COVID Prevention and Treatment?

The beginning of the end or the end of the beginning? After two years mastered by coronavirus disease 19 (COVID-19) pandemic, we are now witnessing a turnaround. The reduction of severe cases and deaths from COVID-19 led to increasing importance of a new disease called post-COVID syndrome. The term post-COVID is used to indicate permanency of symptoms in patients who have recovered from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Immune, antiviral, antimicrobial therapies, as well as ozone therapy have been used to treat COVID-19 disease. Vaccines have then become available and administered worldwide to prevent the insurgence of the disease. However, the pandemic is not over yet at all given the emergence of new omicron variants. New therapeutic strategies are urgently needed. In this view, great interest was found in nutraceutical products, including vitamins (C, D, and E), minerals (zinc), melatonin, probiotics, flavonoids (quercetin), and curcumin. This review summarizes the role of nutraceuticals in the prevention and/or treatment of COVID-19 disease and post-COVID syndrome.

The Concept of Intrauterine Programming and the Development of the Neonatal Microbiome in the Prevention of SARS-CoV-2 Infection

The process of intrauterine programming is related to the quality of the microbiome formed in the fetus and the newborn. The implementation of probiotics, prebiotics, and psychobiotics shows immunomodulatory potential towards the organism, especially the microbiome of the pregnant woman and her child. Nutrigenomics, based on the observation of pregnant women and the developing fetus, makes it possible to estimate the biological effects of active dietary components on gene expression or silencing. Nutritional intervention for pregnant women should consider the nutritional status of the patient, biological markers, and the potential impact of dietary intervention on fetal physiology. The use of a holistic model of nutrition allows for appropriately targeted and effective dietary prophylaxis that can impact the physical and mental health of both the mother and the newborn. This model targets the regulation of the immune response of the pregnant woman and the newborn, considering the clinical state of the microbiota and the pathomechanism of the nervous system. Current scientific reports indicate the protective properties of immunobiotics (probiotics) about the reduction of the frequency of infections and the severity of the course of COVID-19 disease. The aim of this study was to test the hypothesis that intrauterine programming influences the development of the microbiome for the prevention of SARS-CoV-2 infection based on a review of research studies.

Antioxidant/anti-inflammatory effect of Mg2+ in coronavirus disease 2019 (COVID-19)

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19), characterised by high levels of inflammation and oxidative stress (OS). Oxidative stress induces oxidative damage to lipids, proteins, and DNA, causing tissue damage. Both inflammation and OS contribute to multi-organ failure in severe cases. Magnesium (Mg²⁺ ) regulates many processes, including antioxidant and anti-inflammatory responses, as well as the proper functioning of other micronutrients such as vitamin D. In addition, Mg²⁺ participates as a second signalling messenger in the activation of T cells. Therefore, Mg²⁺ deficiency can cause immunodeficiency, exaggerated acute inflammatory response, decreased antioxidant response, and OS. Supplementation with Mg²⁺ has an anti-inflammatory response by reducing the levels of nuclear factor kappa B (NF-κB), interleukin (IL) -6, and tumor necrosis factor alpha. Furthermore, Mg²⁺ supplementation improves mitochondrial function and increases the antioxidant glutathione (GSH) content, reducing OS. Therefore, Mg²⁺ supplementation is a potential way to reduce inflammation and OS, strengthening the immune system to manage COVID-19. This narrative review will address Mg²⁺ deficiency associated with a worse disease prognosis, Mg²⁺ supplementation as a potent antioxidant and anti-inflammatory therapy during and after COVID-19 disease, and suggest that randomised controlled trials are indicated.

Role of the Microbiome in the Pathogenesis of COVID-19

The ongoing pandemic coronavirus disease COVID-19 is caused by the highly contagious single-stranded RNA virus, SARS-coronavirus 2 (SARS-CoV-2), which has a high rate of evolution like other RNA viruses. The first genome sequences of SARS-CoV-2 were available in early 2020. Subsequent whole-genome sequencing revealed that the virus had accumulated several mutations in genes associated with viral replication and pathogenesis. These variants showed enhanced transmissibility and infectivity. Soon after the first outbreak due to the wild-type strain in December 2019, a genetic variant D614G emerged in late January to early February 2020 and became the dominant genotype worldwide. Thereafter, several variants emerged, which were found to harbor mutations in essential viral genes encoding proteins that could act as drug and vaccine targets. Numerous vaccines have been successfully developed to assuage the burden of COVID-19. These have different rates of efficacy, including, although rarely, a number of vaccinated individuals exhibiting side effects like thrombosis. However, the recent emergence of the Britain strain with 70% more transmissibility and South African variants with higher resistance to vaccines at a time when several countries have approved these for mass immunization has raised tremendous concern regarding the long-lasting impact of currently available prophylaxis. Apart from studies addressing the pathophysiology, pathogenesis, and therapeutic targets of SARS-CoV-2, analysis of the gut, oral, nasopharyngeal, and lung microbiome dysbiosis has also been undertaken to find a link between the microbiome and the pathogenesis of COVID-19. Therefore, in the current scenario of skepticism regarding vaccine efficacy and challenges over the direct effects of currently available drugs looming large, investigation of alternative therapeutic avenues based on the microbiome can be a rewarding finding. This review presents the currently available understanding of microbiome dysbiosis and its association with cause and consequence of COVID-19. Taking cues from other inflammatory diseases, we propose a hypothesis of how the microbiome may be influencing homeostasis, pro-inflammatory condition, and the onset of inflammation. This accentuates the importance of a healthy microbiome as a protective element to prevent the onset of COVID-19. Finally, the review attempts to identify areas where the application of microbiome research can help in reducing the burden of the disease.

Malnutrition and Dietary Habits Alter the Immune System Which May Consequently Influence SARS-CoV-2 Virulence: A Review

COVID-19, resulting from the SARS-CoV-2 virus, is a major pandemic that the world is fighting. SARS-CoV-2 primarily causes lung infection by attaching to the ACE2 receptor on the alveolar epithelial cells. However, the ACE2 receptor is also present in intestinal epithelial cells, suggesting a link between nutrition, virulence and clinical outcomes of COVID-19. Respiratory viral infections perturb the gut microbiota. The gut microbiota is shaped by our diet; therefore, a healthy gut is important for optimal metabolism, immunology and protection of the host. Malnutrition causes diverse changes in the immune system by repressing immune responses and enhancing viral vulnerability. Thus, improving gut health with a high-quality, nutrient-filled diet will improve immunity against infections and diseases. This review emphasizes the significance of dietary choices and its subsequent effects on the immune system, which may potentially impact SARS-CoV-2 vulnerability.

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

BACKGROUND

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

SCOPE AND APPROACH

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

KEY FINDINGS AND CONCLUSIONS

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

Leptin in the Respiratory Tract: Is There a Role in SARS-CoV-2 Infection?

Leptin is a pleiotropic adipocytokine involved in several physiologic functions, with a known role in innate and adaptive immunity as well as in tissue homeostasis. Long- and short-isoforms of leptin receptors are widely expressed in many peripheral tissues and organs, such as the respiratory tract. Similar to leptin, microbiota affects the immune system and may interfere with lung health through the bidirectional crosstalk called the “gut-lung axis.” Obesity leads to impaired protective immunity and altered susceptibility to pulmonary infections, as those by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although it is known that leptin and microbiota link metabolism and lung health, their role within the SARS-CoV2 coronavirus disease 2019 (COVID-19) deserves further investigations. This review aimed to summarize the available evidence about: (i) the role of leptin in immune modulation; (ii) the role of gut microbiota within the gut-lung axis in modulating leptin sensitivity; and (iii) the role of leptin in the pathophysiology of COVID-19.

The relevance of magnesium homeostasis in COVID-19

Purpose

In less than one and a half year, the COVID-19 pandemic has nearly brought to a collapse our health care and economic systems. The scientific research community has concentrated all possible efforts to understand the pathogenesis of this complex disease, and several groups have recently emphasized recommendations for nutritional support in COVID-19 patients. In this scoping review, we aim at encouraging a deeper appreciation of magnesium in clinical nutrition, in view of the vital role of magnesium and the numerous links between the pathophysiology of SARS-CoV-2 infection and magnesium-dependent functions.

Methods

By searching PubMed and Google Scholar from 1990 to date, we review existing evidence from experimental and clinical studies on the role of magnesium in chronic non-communicable diseases and infectious diseases, and we focus on recent reports of alterations of magnesium homeostasis in COVID-19 patients and their association with disease outcomes. Importantly, we conduct a census on ongoing clinical trials specifically dedicated to disclosing the role of magnesium in COVID-19.

Results

Despite many methodological limitations, existing data seem to corroborate an association between deranged magnesium homeostasis and COVID-19, and call for further and better studies to explore the prophylactic or therapeutic potential of magnesium supplementation.

Conclusion

We propose to reconsider the relevance of magnesium, frequently overlooked in clinical practice. Therefore, magnesemia should be monitored and, in case of imbalanced magnesium homeostasis, an appropriate nutritional regimen or supplementation might contribute to protect against SARS-CoV-2 infection, reduce severity of COVID-19 symptoms and facilitate the recovery after the acute phase.

Gut and airway microbiota and their role in COVID-19 infection and pathogenesis: a scoping review

Background

The SARS-CoV-2 virus is responsible for the COVID-19 pandemic. Researchers have been studying the pathogenesis of the virus with the aim to improve our current diagnosis and management strategies. The microbiota have been proposed to play a key role in the pathogenesis of the disease.

Purpose

To investigate and report on the current available evidence on any associations between the gut and/or airway microbiota and the pathogenesis of COVID-19.

Methods

Using a predefined protocol in compliance with the PRISMA guidelines, a search was conducted on MEDLINE, Science Direct, DOAJ and Cochrane databases on primary research studies assessing the association between COVID-19 infection and the gut and/or airway microbiota.

Results

Twenty-two studies were included in the current review; nineteen studies concluded an association between the gut and/or airway dysbiosis and SARS-CoV-2, while 3 studies failed to observe a significant association between the airway microbiome and SARS-CoV-2 infection. Specifically, most studies reported a decrease in microbial diversity and therefore development of intestinal dysbiosis in COVID-19-positive patients compared to healthy controls as well as a possible association between increased intestinal dysbiosis and disease severity.

Conclusion

During infection with SARS-CoV-2, there are significant changes in the composition of the gut and airway microbiota. Furthermore, the gut microbiota may have a more important role than the airway microbiota in COVID-19 infection. In the future, studies should be more carefully designed to derive more conclusive evidence on the role of the gut and airway microbiota following infection with SARS-CoV-2 which will lead to the formulation of better management strategies in combating COVID-19.

Supplementary Information

The online version contains supplementary material available at 10.1007/s15010-021-01715-5.

[How does COVID-19 affect intestinal microbiota?]

BACKGROUND

There is a bidirectional interaction between the intestines and lungs, the so-called lung-intestinal axis.

METHOD

The review article reports on studies that deal with a possible influence of the intestinal microbiota on the immune response to a SARS-CoV-2 infection.

RESULTS AND CONCLUSIONS

Studies have shown that COVID-19 is accompanied by dysbiosis that persists even after successful virus conversion (negative PCR). One study found that the severity of COVID-19 is associated with the intestinal microbiota. A dysbiosis could thus favor the so-called cytokine storm. There is indication that pre- and probiotics could boost the immune response in both the guts and lungs.

The Role of Immunobiotics and Postbiotics in the Recovery of Immune Cell Populations From Respiratory Mucosa of Malnourished Hosts: Effect on the Resistance Against Respiratory Infections

Malnutrition is associated with a state of secondary immunodeficiency, which is characterized by a worsening of the immune response against infectious agents. Despite important advances in vaccines and antibiotic therapies, the respiratory infections are among the leading causes of increased morbidity and mortality, especially in immunosuppressed hosts. In this review, we examine the interactions between immunobiotics-postbiotics and the immune cell populations of the respiratory mucosa. In addition, we discuss how this cross talk affects the maintenance of a normal generation of immune cells, that is crucial for the establishment of protective innate and adaptive immune responses. Particular attention will be given to the alterations in the development of phagocytic cells, T and B lymphocytes in bone marrow, spleen and thymus in immunosuppression state by protein deprivation. Furthermore, we describe our research that demonstrated that the effectiveness of immunobiotics nasal administration in accelerating the recovery of the respiratory immune response in malnourished hosts. Finally, we propose the peptidoglycan from the immunobiotic Lactobacillus rhamnosus CRL1505 as the key cellular component for the effects on mucosal immunity, which are unique and cannot be extrapolated to other L. rhamnosus or probiotic strains. In this way, we provide the scientific bases for its application as a mucosal adjuvant in health plans, mainly aimed to improve the immune response of immunocompromised hosts. The search for safe vaccine adjuvants that increase their effectiveness at the mucosal level is a problem of great scientific relevance today.