Host Genotype Links to Salivary and Gut Microbiota by Periodontal Status

Limited evidence describing how host genetic variants affect the composition of the microbiota is currently available. The aim of this study was to assess the associations between a set of candidate host genetic variants and microbial composition in both saliva and gut in the TwinsUK registry. A total of 1,746 participants were included in this study and provided stool samples. A subset of 1,018 participants also provided self-reported periodontal data, and 396 of those participants provided a saliva sample. Host DNA was extracted from whole-blood samples and processed for Infinium Global screening array, focusing on 37 selected single-nucleotide polymorphisms (SNPs) previously associated with periodontitis. The gut and salivary microbiota of participants were profiled using 16S ribosomal RNA amplicon sequencing. Associations between genotype on the selected SNPs and microbial outcomes, including α diversity, β diversity, and amplicon sequence variants (ASVs), were investigated in a multivariate mixed model. Self-reported periodontal status was also compared with microbial outcomes. Downstream analyses in gut microbiota and salivary microbiota were carried out separately. IL10 rs6667202 and VDR 2228570 SNPs were associated with salivary α diversity, and SNPs in IL10, HSA21, UHRF2, and Fc-γR genes were associated with dissimilarity matrix generated from salivary β diversity. The SNP that was associated with the greatest number of salivary ASVs was VDR 2228570 followed by IL10 rs6667202, and that of gut ASVs was NPY rs2521364. There were 77 salivary ASVs and 39 gut ASVs differentially abundant in self-reported periodontal disease versus periodontal health. The dissimilarity between saliva and gut microbiota within individuals appeared significantly greater in self-reported periodontal cases compared to periodontal health. IL10 and VDR gene variants may affect salivary microbiota composition. Periodontal status may drive variations in the salivary microbiota and possibly, to a lesser extent, in the gut microbiota.

Whipple's disease and Tropheryma whippelii: secrets slowly revealed

Whipple's disease was described in 1907 and was designated "intestinal lipodystrophy," despite the detection of bacteria in 1 specimen. This finding was later substantiated by the success of antibiotic therapy, which resulted in dramatic clinical responses, and by use of electron microscopy, which detected monomorphic bacilli in affected tissues. Many attempts at culture failed, and these bacteria were characterized as actinomycetes for the first time by means of broad-range 16S rDNA amplification and molecular phylogenetic methods. The name "Tropheryma whippelii" was proposed for this bacterium. Whipple's disease is a systemic disease that affects many organ systems, producing protean manifestations. This article summarizes recent developments with regard to this topic as well as unanswered questions regarding the pathogenesis and acquisition of infection, the biology and ecology of the organism, the clinical spectrum of disease, diagnosis of the disease, and therapy.

Diagnostic utility of the polymerase chain reaction in 2 cases of suspected Whipple disease

We describe 2 patients with a diagnosis of Whipple disease in whom the usual antibiotic therapy failed. A polymerase chain reaction-based test was used to identify the recently described Whipple bacillus, Tropheryma whippelii. In one case, the diagnosis was confirmed, whereas in the second case, which had been histologically diagnosed as Whipple disease of the brain, the process was identified as a monocyte-derived histiocytosis. In conclusion, Whipple disease can be distinguished from other diseases with similar histological features with the use of a polymerase chain reaction-based test.

Recognition of a bacterial adhesion by an integrin: macrophage CR3 (alpha M beta 2, CD11b/CD18) binds filamentous hemagglutinin of Bordetella pertussis

During the course of whooping cough, Bordetella pertussis interacts with alveolar macrophages and other leukocytes on the respiratory epithelium. We report here mechanisms by which these bacteria adhere to human macrophages in vitro. Whole bacteria adhere by means of two proteins, filamentous hemagglutinin (FHA) and pertussis toxin, either of which is sufficient to mediate adherence. FHA interacts with two classes of molecules on macrophages, galactose-containing glycoconjugates and the integrin CR3 (alpha M beta 2, CD11b/CD18). The interaction between CR3 and FHA involves recognition of the Arg-Gly-Asp (RGD) sequence at positions 1097-1099 in FHA. This study demonstrates that bacterial adherence can be based on the interaction of a bacterial adhesin RGD sequence with an integrin and that bacterial adhesins can have multiple binding sites characteristic of eukaryotic extracellular matrix proteins.

Genetic characterization of Bordetella pertussis filamentous haemagglutinin: a protein processed from an unusually large precursor

The nucleotide sequence of the structural gene for filamentous haemagglutinin (FHA), fhaB, a crucial adherence factor for Bordetella pertussis, has been determined. Its 10774 nucleotides are far more than necessary to encode the 220 kD biologically active, mature polypeptide product, suggesting a role for co- or post-translational processing. Fusion proteins derived from various portions of the fhaB open reading frame (ORF) were used to generate polyclonal antisera. Western immunoblot analysis of purified FHA and Bordetella sp. whole cell extracts with these antisera indicated that the 220 kD product is encoded by the 5' portion of the ORF and that the smaller polypeptide species are breakdown products of this polypeptide. These data, as well as N-terminal amino acid sequencing of the major polypeptide species, suggest a scheme for the proteolytic processing of an FHA precursor polypeptide.