Mapping the global research landscape on nutrition and the gut microbiota: Visualization and bibliometric analysis

BACKGROUNDNutrition is a significant modifiable element that influences the composition of the gastrointestinal microbiota, implying the possibility of therapeutic diet methods that manipulate the composition and diversity of the microbial.AIMTo overview research papers on nutrition and gut microbiota and determines the hotspots in this field at the global level.METHODSScopus and Reference Citation Analysis were used to construct a bibliometric technique. It was decided to create bibliometric indicators and mapping as in most previous studies. 2012 through 2021 served as the study''s timeframe.RESULTSA total of 5378 documents from the Scopus database were selected for analysis. Of all retrieved studies, 78.52% were research papers (n = 4223), followed by reviews (n = 820; 15.25%). China ranked first with a total number of articles of 1634 (30.38%), followed by the United States in second place with a total number of articles of 1307 (24.3%). In the last decade, emerging hotspots for gut microbiota and nutrition research included gut microbiota metabolism and interaction with dietary components, connection between the gut microbiota and weight gain, and the influence of high-fat diet and gut microbiota on metabolic disorders.CONCLUSIONThis is the first thorough bibliometric analysis of nutrition and gut microbiota publications conducted on a global level. Investigation of the association between nutrition/diet and the gut microbiota is still in its infancy and will be expanded in the future. However, according to recent trends, the “effect of gut microbiota and high-fat diet on metabolic disorders will be an increasing concern in the future.     

Gut dysbiosis and body composition in cirrhosis

BACKGROUNDGut dysbiosis and changes in body composition (i.e., a decrease in the proportion of muscle mass and an increase in extracellular fluid) are common in cirrhosis.AIMTo study the relationship between the gut microbiota and body composition in cirrhosis.METHODSThis observational study included 46 patients with cirrhosis. Stool microbiome was assessed using 16S rRNA gene sequencing. Multifrequency bioelectrical impedance analysis was performed to assess body composition in these patients.RESULTSAn increase in fat mass and a decrease in body cell mass were noted in 23/46 (50.0%) and 15/46 (32.6%) patients, respectively. Changes in the gut microbiome were not independently associated with the fat mass percentage in cirrhosis. The abundance of Bacteroidaceae (P = 0.041) and Eggerthella (P = 0.001) increased, whereas that of Erysipelatoclostridiaceae (P = 0.006), Catenibacterium (P = 0.021), Coprococcus (P = 0.033), Desulfovibrio (P = 0.043), Intestinimonas (P = 0.028), and Senegalimassilia (P = 0.015) decreased in the gut microbiome of patients with body cell mass deficiency. The amount of extracellular fluid increased in 22/46 (47.6%) patients. Proteobacteria abundance (P < 0.001) increased, whereas Firmicutes (P = 0.023), Actinobacteria (P = 0.026), Bacilli (P = 0.008), Anaerovoraceceae (P = 0.027), Christensenellaceae (P = 0.038), Eggerthellaceae (P = 0.047), Erysipelatoclostridiaceae (P = 0.015), Erysipelotrichaceae (P = 0.003), Oscillospiraceae (P = 0.024), Rikenellaceae (P = 0.002), Collinsella (P = 0.030), Hungatella (P = 0.040), Peptococcaceae (P = 0.023), Slackia (P = 0.008), and Senegalimassilia (P = 0.024) abundance decreased in these patients. Patients with clinically significant ascites (n = 9) had a higher abundance of Proteobacteria (P = 0.031) and a lower abundance of Actinobacteria (P = 0.019) and Bacteroidetes (P = 0.046) than patients without clinically significant ascites (n = 37).CONCLUSIONChanges in the amount of body cell mass and extracellular fluid are associated with changes in the gut microbiome in cirrhosis patients.     

High fat diet induced gut dysbiosis alters corneal epithelial injury response in mice

PurposeCommensal microbiome secretes various metabolites that can exert important effects on the host immunity and inflammation and can alter cellular functions. However, little is known regarding the effect of microbiome on corneal immunity and genetic expression. The purpose of this study is to describe the effect of diet-induced gut dysbiosis on corneal immunity and corneal gene expression after wounding.MethodsThis study is approved by the Animal Care and Use of the University of Illinois. Six-week-old female C57BL6 mice were fed on a normal chow diet (ND), isocaloric low-fat control diet (LFD), or a 21% milk high-fat diet (HFD) for six weeks. 2 mm corneal epithelial debridement was performed (n = 10). Fecal samples from mice were used for microbial diversity analysis (n > 3). Immunofluorescence staining of corneal wholemount tissue post-debridement was used to visualize immune cell distribution. RNA Seq was performed on tissue samples from corneas following debridement.ResultsMice fed differing diets had significant alterations in gut microbial diversities. After corneal debridement, HFD mice experienced delayed wound healing in comparison to LFD mice and ND mice groups. However, fecal transplantation led to normalization of wound closure rates. Increased γδTCR staining was observed in the LFD group, and decreased LY6G was observed in HFD group (p < 0.05). Gene Ontology terms of differentially expressed genes included response to external stimulus, cell proliferation, migration, adhesion, defense response and leukocyte migration. Top over-represented pathways included ECM-receptor interaction, Cytokine-cytokine receptor interaction, Focal adhesion and Leukocyte trans-endothelial migration.ConclusionsGut microbial dysbiosis alters corneal immune cell distribution, corneal response to injury, and genes related to epithelial function and corneal immunity.     

Maternal effects in mammals: Broadening our understanding of offspring programming

The perinatal period is a sensitive time in mammalian development that can have long-lasting consequences on offspring phenotype via maternal effects. Maternal effects have been most intensively studied with respect to two major conditions: maternal diet and maternal stress. In this review, we shift the focus by discussing five major additional maternal cues and their influence on offspring phenotype: maternal androgen levels, photoperiod (melatonin), microbiome, immune regulation, and milk composition. We present the key findings for each of these topics in mammals, their mechanisms of action, and how they interact with each other and with the maternal influences of diet and stress. We explore their impacts in the contexts of both predictive adaptive responses and the developmental origins of disease, identify knowledge gaps and research opportunities in the field, and place a particular emphasis on the application and consideration of these effects in non-model species and natural ecological systems.     

How biological sex of the host shapes its gut microbiota

The gut microbiota is a complex system, consisting of a dynamic population of microorganisms, involved in the regulation of the host’s homeostasis. A vast number of factors are driving the gut microbiota composition including diet, antibiotics, environment, and lifestyle. However, in the past decade, a growing number of studies also focused on the role of sex in relationship to changes in the gut microbiota composition in animal experiments as well as in human beings. Despite the progress in investigation techniques, still little is known about the mechanism behind the observed sex-related differences. In this review, we summarized current knowledge on the sex-dependent differences of the intestinal commensals and discuss the probable direct impact of sex hormones and more indirect effects such as dietary habits or antibiotics. While we have to conclude limited data on specific developmental stages, a clear role for sexual hormones and most probably for testosterone emerges.     

Targeted microbiome-sparing antibiotics

A factor in our inability to meet the challenge of clinical antibiotic resistance has been the low productivity of research and development (R&D) efforts, with only incremental improvements on existing broad-spectrum classes coming into clinical use recently. The disappointing returns from this approach have focussed attention on narrower-spectrum antibiotics; such new agents are directed against the pathogen of relevance with the additional benefit of preserving the human microbiome(s). Our knowledge of the gut microbiome and its contribution to health homeostasis increases yearly and suggests that broad-spectrum treatments incur health costs beyond the initial infection. Improved diagnostics, antibiotic stewardship, and the crucial role of the gut microbiome in health indicate targeted agents as a more viable approach for future antibiotic R&D.     

Relationship between healing status and microbial dissimilarity in wound and peri-wound skin in pressure injuries

AimWound infection is the most serious cause of delayed healing for patients with pressure injuries. The wound microbiota, which plays a crucial role in delayed healing, forms by bacterial dissemination from the peri-wound skin. To manage the bioburden, wound and peri-wound skin care has been implemented; however, how the microbiota at these sites contribute to delayed healing is unclear. Therefore, we investigated the relationship between healing status and microbial dissimilarity in wound and peri-wound skin.MethodsA prospective cohort study was conducted at a long-term care hospital. The outcome was healing status assessed using the DESIGN-R® tool, a wound assessment tool to monitor the wound healing process. Bacterial DNA was extracted from the wound and peri-wound swabs, and microbiota composition was analyzed using 16S rRNA gene analysis. To evaluate microbial similarity, the weighted UniFrac dissimilarity index between wound and peri-wound microbiota was calculated.ResultsTwenty-two pressure injuries (7 deep and 15 superficial wounds) were included in the study. For deep wounds, the predominant bacteria in wound and peri-wound skin were the same in the healing wounds, whereas they were different in all cases of hard-to-heal wounds. Analysis based on the weighted UniFrac dissimilarity index, there was no significant difference for healing wounds (p = 0.639), while a significant difference was found for hard-to-heal wounds (p = 0.047).ConclusionsDelayed healing is possibly associated with formation of wound microbiota that is different in composition from that of the skin commensal microbiota. This study provides a new perspective for assessing wound bioburden.     

Emerging Tests for Noninvasive Colorectal Cancer Screening

Colorectal cancer (CRC) is among the most common cancers globally and a major cause of cancer-related deaths. The American Cancer Society estimates that CRC will kill 1 in 60 Americans, and CRC screening is recommended for all Americans ≥45 years of age. Current CRC screening methods are effective for preventing CRC and have been shown to reduce CRC-related mortality. However, none of the currently available tests is ideal, and many people are not compliant with screening recommendations. Novel screening tests based on advances in CRC molecular biology, genetics, and epigenetics, combined with developments in sequencing technologies and computational analytic methods, have been developed to address the shortcomings of current CRC screening tests. These emerging tests include blood-based assays that use plasma-derived circulating tumor DNA and serum proteins to detect early CRC and advanced adenomas, assays that use stool DNA or mRNA, and methods for profiling the gut microbiome. Here we review current screening modalities, and we discuss the principles behind the most promising emerging CRC screening tests and the data supporting their potential to be used in clinical practice.     

Human Gut Microbiota and Its Metabolites Impact Immune Responses in COVID-19 and Its Complications

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