Bacteroidaceae, Bacteroides, and Veillonella: emerging protectors against Graves' disease

Background

Graves' disease (GD) is the most common cause of hyperthyroidism, and its pathogenesis remains incompletely elucidated. Numerous studies have implicated the gut microbiota in the development of thyroid disorders. This study employs Mendelian randomization analysis to investigate the characteristics of gut microbiota in GD patients, aiming to offer novel insights into the etiology and treatment of Graves' disease.

Methods

Two-sample Mendelian randomization (MR) analysis was employed to assess the causal relationship between Graves' disease and the gut microbiota composition. Gut microbiota data were sourced from the international consortium MiBioGen, while Graves' disease data were obtained from FINNGEN. Eligible single nucleotide polymorphisms (SNPs) were selected as instrumental variables. Multiple analysis methods, including inverse variance-weighted (IVW), MR-Egger regression, weighted median, weighted mode, and MR-RAPS, were utilized. Sensitivity analyses were conducted employing MR-Egger intercept test, Cochran's Q test, and leave-one-out analysis as quality control measures.

Results

The Mendelian randomization study conducted in a European population revealed a decreased risk of Graves' disease associated with Bacteroidaceae (Odds ratio (OR) [95% confidence interval (CI)]: 0.89 [0.89 ~ 0.90], adjusted P value: <0.001), Bacteroides (OR: [95% CI]: 0.555 [0.437 ~ 0.706], adjusted P value: <0.001), and Veillonella (OR [95% CI]: 0.632 [0.492 ~ 0.811], adjusted P value: 0.016). No significant evidence of heterogeneity, or horizontal pleiotropy was detected. Furthermore, the preliminary MR analysis identified 13 bacterial species including Eubacterium brachy group and Family XIII AD3011 group, exhibiting significant associations with Graves' disease onset, suggesting potential causal effects.

Conclusion

A causal relationship exists between gut microbiota and Graves' disease. Bacteroidaceae, Bacteroides, and Veillonella emerge as protective factors against Graves' disease development. Prospective probiotic supplementation may offer a novel avenue for adjunctive treatment in the management of Graves' disease in the future.

The impact of gut microbiome enterotypes on ulcerative colitis: identifying key bacterial species and revealing species co-occurrence networks using machine learning

Ulcerative colitis (UC) is a chronic inflammatory intestinal disease affecting the colon and rectum, with its pathogenesis attributed to genetic background, environmental factors, and gut microbes. This study aimed to investigate the role of enterotypes in UC by conducting a hierarchical analysis, determining differential bacteria using machine learning, and performing Species Co-occurrence Network (SCN) analysis. Fecal bacterial data were collected from UC patients, and a 16S rRNA metagenomic analysis was performed using the QIIME2 bioinformatics pipeline. Enterotype clustering was conducted at the family level, and deep neural network (DNN) classification models were trained for UC and healthy controls (HC) in each enterotype. Results from eleven 16S rRNA gut microbiome datasets revealed three enterotypes: Bacteroidaceae (ET-B), Lachnospiraceae (ET-L), and Clostridiaceae (ET-C). Ruminococcus (R. gnavus) abundance was significantly higher in UC subjects with ET-B and ET-C than in those with ET-L. R. gnavus also showed a positive correlation with Clostridia in UC SCN for ET-B and ET-C subjects, with a higher correlation in ET-C subjects. Conversely, Odoribacter (O.) splanchnicus and Bacteroides (B.) uniformis exhibited a positive correlation with tryptophan metabolism and AMP-activated protein kinase (AMPK) signaling pathways, while R. gnavus showed a negative correlation. In vitro co-culture experiments with Clostridium (C.) difficile demonstrated that fecal microbiota from ET-B subjects had a higher abundance of C. difficile than ET-L subjects. In conclusion, the ET-B enterotype predisposes individuals to UC, with R. gnavus as a potential risk factor and O. splanchnicus and B. uniformis as protective bacteria, and those with UC may have ultimately become ET-C.

Probiotics ameliorate benzene-induced systemic inflammation and hematopoietic toxicity by inhibiting Bacteroidaceae-mediated ferroptosis

The intestinal microbiota is associated with the development of benzene-induced hematopoietic toxicity. Modulation of intestinal homeostasis by probiotic supplementation has been considered an effective strategy to prevent adverse health effects. However, the role and mechanism of probiotics in benzene-induced hematopoietic toxicity are unclear. After 45 days of exposure, benzene caused bone marrow hematopoietic toxicity in mice. Furthermore, we found that benzene altered the intestinal barrier in mice, leading to an increase in the abundance of Bacteroidaceae and the activation of systemic inflammation. Interestingly, Fe2+ accumulation, lipid peroxidation, and differential expression of ferroptosis proteins were observed in the intestinal tissues of benzene-exposed mice. After fecal microbiota transplantation, stool microbes from benzene-exposed mice led to the development of intestinal ferroptosis in recipient mice. In particular, oral probiotics significantly reversed elevated Bacteroidaceae and intestinal ferroptosis, ultimately improving benzene-induced hematopoietic damage. We further used the benzene metabolite 1,4-BQ to treat human normal colonic epithelial cells (NCM460) and intervened with the ferroptosis inhibitor liproxstatin-1 (Lip-1) to validate the relationship between intestinal ferroptosis and inflammation. The results showed that 1,4-BQ treatment resulted in increased intracellular ROS levels and abnormal expression of ferroptosis proteins and the inflammatory factors IL-5 and IL-13. However, the use of Lip-1 significantly inhibited oxidative stress, ferroptosis, and inflammation in NCM460 cells. This result suggested that ferroptosis might be involved in benzene-induced hematopoietic toxicity by mediating Th2-type systemic inflammation. Overall, these findings revealed a role for Bacteroidaceae-intestinal ferroptosis-inflammation in benzene-induced hematopoietic toxicity and highlighted that probiotics could be a promising strategy to prevent adverse hematologic outcomes.

A Globally Distributed Bacteroides caccae Strain Is the Most Prevalent Mother-Child Shared Bacteroidaceae Strain in a Large Scandinavian Cohort

Bacteroides and Phocaeicola, members of the family Bacteroidaceae, are among the first microbes to colonize the human infant gut. While it is known that these microbes can be transmitted from mother to child, our understanding of the specific strains that are shared and potentially transmitted is limited. In this study, we aimed to investigate the shared strains of Bacteroides and Phocaeicola in mothers and their infants. We analyzed fecal samples from pregnant woman recruited at 18 weeks of gestation from the PreventADALL study, as well as offspring samples from early infancy, including skin swab samples taken within 10 min after birth, the first available fecal sample (meconium), and fecal samples at 3 months of age. We screened 464 meconium samples for Bacteroidaceae, with subsequent selection of 144 mother-child pairs for longitudinal analysis, based on the presence of Bacteroidaceae, longitudinal sample availability, and delivery mode. Our results showed that Bacteroidaceae members were mainly detected in samples from vaginally delivered infants. We identified high prevalences of Phocaeicola vulgatus, Phocaeicola dorei, Bacteroides caccae, and Bacteroides thetaiotaomicron in mothers and vaginally born infants. However, at the strain level, we observed high prevalences of only two strains: a B. caccae strain and a P. vulgatus strain. Notably, the B. caccae strain was identified as a novel component of mother-child shared strains, and its high prevalence was also observed in publicly available metagenomes worldwide. Our findings suggest that mode of delivery may play a role in shaping the early colonization of the infant gut microbiota, in particular the colonization of Bacteroidaceae members. IMPORTANCE Our study provides evidence that Bacteroidaceae strains present on infants' skin within 10 min after birth, in meconium samples, and in fecal samples at 3 months of age in vaginally delivered infants are shared with their mothers. Using strain resolution analyses, we identified two strains, belonging to Bacteroides caccae and Phocaeicola vulgatus, as shared between mothers and their infants. Interestingly, the B. caccae strain showed a high prevalence worldwide, while the P. vulgatus strain was less common. Our findings also showed that vaginal delivery was associated with early colonization of Bacteroidaceae members, whereas cesarean section delivery was associated with delayed colonization. Given the potential for these microbes to influence the colonic environment, our results suggest that understanding the bacterial-host relationship at the strain level may have implications for infant health and development later in life.

Intestinal microbiota and allergic diseases: A systematic review

Evidence suggests that possible imbalances in intestinal microbiota composition may be implicated in the occurrence of allergic diseases. Although several studies published until 2006 indicated a correlation between microbiota composition and allergic symptoms, it has not been possible to distinguish protective microorganisms from those associated with increased risk of allergic diseases. Therefore, the objective of this study was to review the studies published since 2007 that address the intestinal microbiota in allergic diseases. Twenty-one studies were identified after excluding those that performed a clinical intervention before stool collection. In the early microbiota of children who later developed allergies, lower bacterial diversity was observed, with a predominance of Firmicutes; a higher count of Bacteroidaceae; a higher prevalence of the anaerobic bacteria Bacteroides fragilis, Escherichia coli, Clostridium difficile, Bifidobacterium catenulatum, Bifidobacterium bifidum, and Bifidobacterium longum; and a lower prevalence of Bifidobacterium adolescentis, B. bifidum, and Lactobacillus. In the microbiota of allergic children whose intestinal microbiota was assessed at the onset of allergic symptoms, there was a higher count of Bacteroides; a lower count of Akkermansia muciniphila, Faecalibacterium prausnitzii, and Clostridium; a higher prevalence of B. adolescentis; a lower prevalence of B. catenulatum and Staphylococcus aureus; and a lower bacterial diversity.

Establishment of specific pathogen-free (SPF) rat colonies using gnotobiotic techniques

Gnotobiotic Wistar rats were produced using gnotobiotic techniques, which were established in the production of a SPF mouse colony, in order to establish a barrier-sustained colony. One strain of Escherichia coli, 28 strains of Bacteriodaceae (B-strains), three strains of Lactobacillus (L-strains) and a chloroform-treated fecal suspension (CHF, Clostridium mixture) were prepared from conventional Wistar rats as the microflora source. Two groups of limited-flora rats, E. coli plus B-strains and E. coli plus CHF, were produced. After confirmation that Clostridium difficile was not detected in the CHF-inoculated rats, two groups of limited-flora rats were transferred to an isolator and housed together in a cage. These rats were then orally inoculated with L-strains. The gnotobiotic rats showed colonization resistance to Pseudomonas aeruginosa, and the number of E. coli in the feces was 10(5) to 10(6)/g. The gnotobiotic rats were transferred to a barrier room as a source of intestinal flora for SPF colonies. In the SPF rats, basic cecal flora was mainly composed of Bacteroidaceae, clostridia, fusiform-shaped bacteria and lactobacilli, and did not change over a long period. Their flora became similar to that of conventional rats.

Bacteraemia with Leptotrichia buccalis: report of a case and review of the literature

We report here on a new case of L. buccalis bacteraemia. To our knowledge 16 other cases of L. buccalis bacteraemia have been reported in the literature, most of them in neutropenic patients. However L buccalis endocarditis does occasionally occur in non-neutropenic patients. The identification of L. buccalis is based on well known phenotypic features and confirmed by the detection of a large peak of lactic acid by gas chromatography for non volatile organic acids. L. buccalis is sensitive to a wide range of antibiotics including beta-lactam antibiotics, but it is resistant to aminoglycosides and macrolides.

Necrotizing ulcerative gingivitis, periodontitis, and stomatitis: clinical staging and predisposing factors

Necrotizing ulcerative gingivitis (NUG), necrotizing ulcerative periodontitis (NUP), and necrotizing stomatitis (NS), collectively termed necrotizing gingivostomatitis (NG), represent a dramatic, but rare oral infection associated with diminished systemic resistance, including HIV infection. Over a 5-year period, 68 consecutive NG patients from a population with known HIV status were evaluated and treated. Lesions were staged (modified Pindborg), and clinical findings and predictor variables were compared to 68 random control subjects without NG. Most cases (52%) were stage 1, with necrosis of the tip of the interdental papilla only; 19% were stage 2, with the entire papilla affected; 22% had necrosis of marginal (stage 3) or attached gingiva (stage 4); and 7% were more advanced, with mucosal necrosis or bone exposure. Attachment loss was a feature of stage 2 or greater NG. Beside HIV infection, significant predisposing factors included poor oral hygiene, unusual life stress, inadequate sleep, Caucasian race, age 18 to 21 years, and recent illness. Ten of 68 NG patients were HIV-positive. These patients were older than seronegative patients, less likely to be Caucasian, and maintained better oral hygiene and sleep. HIV-positive NG cases were clinically indistinguishable from HIV-negative cases in this series.

Kinin generation in the gingival inflammatory response to topically applied bacterial lipopolysaccharides

A water-soluble lipopolysaccharide from Salmonella enteritidis and a phenol-soluble lipopolysaccharide from Leptotrichia buccalis were applied topically to the healthy marginal gingivae of beagle dogs. Saline was applied to contralateral areas as an internal control. Increases in vascular permeability were monitored by measurement of gingival fluid, and the collected gingival fluid samples were assayed for kininogenase and kinin activities. Both lipopolysaccharides induced an inflammatory response, as indicated by increased gingival fluid flow. Kininogenase-kinin activities paralleled the increases in gingival fluid flow, with the highest values being associated with peak increases in gingival fluid. The results indicate that both lipopolysaccharides, although different in lipid solubility, penetrate healthy sulcular epithelium and initiate an inflammatory response which is mediated in part by the kallikrein-kinin system. Interrelationships between this system and other inflammatory mediators suggest that kinin generation not only plays a role in the early phases of acute gingival inflammation, but may also contribute to the activation of other mediators appearing later in the response and in chronic inflammatory lesions.

Infective endocarditis due to Leptotrichia buccalis: a case report

A patient with Down's syndrome presented with infective endocarditis due to Leptotrichia buccalis. The source of the infection was not detected, but the predisposing factor was a complex cardiac malformation. The disease followed a subacute course, had a number of immunologic manifestations and was successfully treated with a 28-day course of penicillin G, given intravenously. L. buccalis has never been reported before as a cause of endocarditis.

The gram-negative bacillary pneumonias

With increasing age, chronic underlying disease, and debility, the oropharyngeal flora are colonized with aerobic gram-negative bacilli. In this debilitated population, gram-negative bacillary pneumonias (GNBP) are increasingly common. GNBP account for two of every three pneumonia deaths today. As a group, the mortality of GNBP is about 50%. Although the original epidemiologic surveys were done 15 years ago, there is little evidence for an improving case fatality rate despite the appearance of aminoglycoside antibiotics, carbenicillin, and cephalosporins. In susceptible patients, GNBP pneumonias occur both in the community and as nosocomial infections. Recognition of the dangers of contaminated reservoir nebulizers or other similar devices used in inhalation therapy has led to epidemiologic measures within hospitals that have markedly decreased the incidence of this nosocomial GNBP. The role of Gram stain and culture of expectorated sputum and similar examinations of specimens obtained by transtracheal aspiration, fiberoptic bronchoscopy, and lung biopsy in the diagnosis of GNBP are discussed in this review (see Criteria for Diagnosis). In the presence of pulmonary emphysema, congestive heart failure, mixed gram-negative bacillary infections, or the use of immunosuppressive drugs, typical characteristics of individual GNBP may not be apparent. Typical features of Pseudomonas aeruginosa, Escherichia coli, Enterobacter, Proteus, Hemophilus, and anaerobic pulmonary infections are described. Early recognition and institution of appropriate antibacterial agents are emphasized, particularly in GNBP caused by Pseudomonas aeruginosa, Escherichia coli, or Friedländer's bacillus, where the mortality approaches 70%. The mortality of GNBP, including Enterobacter, Proteus, Hemophilus, and anaerobic GNBP, is about 20%. The latter figure is the same as the mortality of pneumococcal pneumonia in similar patients.