| Purpose: To investigate the composition and diversity of bacterial community on the ocular surface of patients with meibomian gland dysfunction(MGD)via 16 S rDNA sequencing.Methods:(1)Forty-seven patients with MGD,who were divided into groups of mild,moderate,and severe MGD depending on eyelid margin signs,clinical symptoms,and quality of meibum,and 42 sex-and age-matched participants without MGD(control group)were enrolled.(2)Samples were collected from the upper and lower conjunctival sac of one randomly chosen eye of each participant.(3)Through sequencing the hypervariable region of 16 S rDNA gene obtained from samples,differences in the taxonomy and diversity between groups were compared.(4)Mann-Whitney U was performed for analyses of the ?-diversity indices and the relative abundances of dominant phyla and genera between groups.Spearman correlation analysis was used to measure the correlation between meiboscores and relative abundances of Staphylococcus in patients with MGD.Results:(1)Forty-seven patients with meibomian gland dysfunction and 42 normal subjects were collected from conjunctival sac for 16 S rDNA analysis.A total of 1,596,000 raw tags were obtained.(2)There was no significant difference in the Chao1 index,Simpson index,Shannon index or observed-species index among the four groups(P>0.05,Mann-Whitney U).(3)At the phylum level,the major phyla in the patients with MGD included Actinobacteria(34.17%,1.26%?87.11%),Firmicutes(31.70%,3.34%?90.60%),Proteobacteria(27.46%,2.30%?84.48%),Bacteroidetes(2.21%,0.02%?10.54%),and Deinococcus-Thermus(1.19%,0%?8.96%).The relative abundances of Firmicutes(31.70% vs.19.67%)and Proteobacteria(27.46% vs.14.66%)were significantly higher(P< 0.05,Mann-Whitney U),and the abundance of Actinobacteria(34.17% vs.56.98%)was lower in MGD than controls(P< 0.05,Mann-Whitney U).At the genus level,the predominant genus in patients with MGD was Staphylococcus(20.71%,0.20%?87.01%),followed by Corynebacterium(20.22%,0.09%?85.20%),Propionibacterium(9.29%,0.05%?59.64%),Sphingomonas(5.73%,0.36%?22.75%),Snodgrassella(4.17%,0%?68.12%),and Streptococcus(2.80%,0%?22.28%).The abundances of Staphylococcus(20.71% vs.7.88%)and Sphingomonas(5.73% vs.0.79%)in patients with MGD were significantly higher than the controls(P< 0.05,Mann-Whitney U),while the abundance of Corynebacterium(20.22% vs.46.23%)was significantly lower(P< 0.05,Mann-Whitney U).LEf Se analysis showed that at the phylum level,the biomarkers of MGD group were Proteobacteria and Firmicutes,while the control group was Actinobacteria.At the genus level,Staphylococcus and Sphingomonas were used as biomarkers in the MGD group,and Corynebacterium was used as biomarkers in the control group.(4)Principal coordinate analysis showed that the clustering of bacterial communities in the conjunctiva sac in the severe MGD group was significantly different from that in other groups.At the genus level,the relative abundances of Corynebacterium in the control group and the mild MGD group were significantly higher than that in the moderate MGD group and the severe MGD group(P < 0.05,Mann-Whitney U).Meanwhile,the relative abundance of Staphylococcus in the severe MGD group was significantly higher than that in other groups(P < 0.05,Mann-Whitney U).(5)The abundance of Staphylococcus was positively correlated with the meiboscores in patients with MGD(r=0.650,P< 0.001,Spearman).Conclusion: Patients with MGD can have various degrees of bacterial microbiota imbalance in the conjunctival sac.There were significant differences in Staphylococcus,Corynebacterium,and Sphingomonas between MGD patients and control group. |
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