Effect of tablets containing probiotic candidate strains on gingival inflammation and composition of the salivary microbiome: a randomised controlled trial.

The aim of the study was to investigate clinical and microbial effects of probiotic candidate strains in patients with moderate gingivitis. The null hypothesis was that the clinical measurements with treatment would not differ from placebo. 47 adult patients were enrolled in a randomised placebo-controlled trial with a 4-week intervention of tablets containing a mix of Lactobacillus rhamnosus PB01, DSM 14869 and Lactobacillus curvatus EB10, DSM 32307 or placebo. Clinical examinations and samplings were done at baseline and after 2, 4 and 6 weeks. The clinical endpoints were general bleeding on probing (BOP), general plaque index (PI) and flow of gingival crevicular fluid (GCF). In addition, the concentration of selected cytokines (interleukin (IL)-1ß, IL-6, IL-8, IL-10, tumour necrosis factor alpha (TNF-α)) in GCF was determined with multiplex immunoassays. The profiles of the salivary microbiome were analysed with Next Generation Sequencing (NGS) and qPCR. In contrast to the placebo group, there was a significant reduction in BOP and amount of GCF (P<0.05) after 4 weeks in the probiotic test group when compared with baseline. The general PI was less affected although there was a tendency of decreased plaque levels in the probiotic group (P=0.05-0.09). The cytokines were unaffected by the intervention as well as the salivary microbiome. The Shannon index showed no significant differences between the groups or alterations over time. The occurrence of both probiotic strains increased in saliva of the test subjects during the intervention but returned to baseline levels within 2 weeks. Although a marked improvement in gingival health was recorded in the probiotic group, the null hypothesis could not be rejected.

Our gut microbiota: a long walk to homeostasis.

The microbiome of the human gastrointestinal tract (GIT) consists of billions of bacteria, fungi and viruses, of which bacteria play the most important role in nutrition, immune development, production of vitamins and maintaining a well-balanced (homeostatic) microbial population. Many papers have been published on the microbiota in the human GIT, but little is known about the first group of bacteria that colonises an infant. The intestinal tract of an unborn is, despite general belief, not sterile, but contains bacteria that have been transferred from the mother. This opens a new research field and may change our understanding about the role bacteria play in early life, the selection of strains with probiotic properties and the treatment of diseases related to bacterial infections. Differences in bacterial populations isolated from meconia may provide answers to the prevention of certain forms of diabetes. More research is now focusing on the effect that a genetically diverse group, versus a much simpler microbial population, may have on the development of a homeostatic gut microbiome. The effect different bacterial species have on the gut-associated lymphoid tissue and cascade of immune responses has been well researched, but we still fail in identifying the ideal group of intestinal bacteria and if we do, it will certainly not be possible to maintain homeostasis with so many challenges the gut faces. Changes in diet, antibiotics, food preservatives and stress are some of the factors we would like to control, but more than often fail to do so. The physiology and genetics of the GIT changes with age and so the microbiome. This review summarises factors involved in the regulation of a gut microbiome.