| Objective: Traditional Chinese Medicine(TCM),practiced by generations of Chinese doctors,has been abundantly used in the clinic.Tongue diagnosis has many advantages as it is non-invasive and convenient.However,it is not widely approved due to its subjectivity and non-reproducibility.The goals of this study were to reveal the relationship between tongue coating appearance and the oral microbiota in patients with gastric cancer and to open a novel research direction supporting tongue diagnosis and gastric cancer research.Methods: The DS01-B tongue manifestation acquisition instrument was used to analyze the thickness of the tongue coating of 74 patients with gastric cancer and that of 72 healthy controls and divided them into thick tongue coatings and thin tongue coatings according to the manual of the DS01-B tongue manifestation acquisition instrument at the threshold of 300.All subjects were divided into three groups,HCs with thin tongue coatings,patients with thin tongue coatings and patients with thick tongue coatings.Collected the total DNA of tongue coating microbiota,high-throughput sequencing was used to describe the microbial community of the tongue coating by sequencing the V2-V4 region of the 16 S r DNA.To obtain accurate data,we eliminated unqualified reads and filtered sequences were binned into OTUs with the QIIME pipeline.To perform the taxonomic analysis,each OTU was aligned to the SILVA database.To estimate the diversity of the microbial community in the tongue coatings,abundance-based coverage estimator(ACE),Chao and Shannon indicates were used to describe the alpha diversity.And analyzed population structure and richness based on each of the following five categories: phylum,class,order, family and genus.Results: Using the DS01-B tongue manifestation acquisition instrument,we found that the tongue coatings of 74 patients with gastric cancer were significantly thicker than those of 72 healthy controls(343.11±198.22 vs.98.42±48.25,P<0.001);51.35% of the patients were assessed as having thick tongue coatings,whereas all healthy controls were assessed as having thin tongue coatings.To obtain better samples for the next-generation sequencing,we selected 50 samples to for the next-generation sequencing,therefore,there were the three following groups: HCs with thin tongue coatings(n=16),patients with thin tongue coatings(n=16)and patients with thick tongue coatings(n=18).In 50 samples we identified 512575267 bps in 1155532 reads,and the taxonomic analysis we found 20 phyla,162 genera and350 species;Compared the three groups,we found that that patients with thick tongue coatings have lower microbial community diversity than patients and healthy people with thin tongue coatings.The five genera with the greatest relative abundances in patients with thin tongue coatings were Prevotella,Veillonella,Leptotrichia,Lactococcus and Streptococcus,and those of patients with thick tongue coatings were Prevotella,Streptococcus,Actinomyces,Veillonella and Leptotrichia.Patients with thick tongue coatings had higher relative abundances of Actinomyces and Streptococcus.At the level of species,we found that the majority of species were shared among the three groups.A Venn diagram of the diversity at the species level showed that 225 species were shared among the three groups,32 species were not detected in patients,47 species were not detected in healthy controls,and 17 species were detected only in thick tongue coatings.Compared patients with controls,we found that the relative abundances of Firmicutes,Bacteroidetes,Fusobacteria and TM7 were similar between patients and controls.However,there were significant differences in the abundances of Proteobacteria(10.85% vs.28.55% relative abundance for patients and controls,respectively,P<0.001)and Actinobacteria(12.32% vs.4.46%,respectively,P<0.001).Proteobacteria accounted for 28.55% of the tongue-coating microbes from health controls(ranging from 11.70% to 42.99%)and 10.85% of the tongue-coating microbes from gastric cancer patients(ranging from 0.11% to 34.77%).Relative abundance levels of less than 15% were determined for Proteobacteria in only 1 of 16 health controls but in 25 of 34 gastric cancer patients.Conclusion: 1)The tongue coatings of patients with GC are significantly thicker than those of health controls;2)The tongue coating microbiota community is correlated with the appearance of the tongue coating,and gastric cancer patients with thick tongue coatings had decreased microbial community diversity compared with those of patients and healthy people with thin tongue coatings.3)Patients with gastric cancer have different oral microbial community structures,which may become a biological approach for gastric cancer prevention and diagnosis. |
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