Characterization of Conjunctival Sac Microbiome from Patients with Allergic Conjunctivitis.

Hang Song,Hanyi Min,Zhengyu Chen,Kang Xiao,Qin Long

doi:10.3390/jcm11041130

Abstract

Conjunctival sac microbiome alterations have been reported to be closely associated with many ocular diseases. However, the characteristic of conjunctival sac microbiome in allergic conjunctivitis (AC) was scarcely described. In this study, we aimed to identify the differences of the conjunctival sac microbiome composition in AC patients compared with normal controls (NCs) using high-throughput 16S rDNA sequencing metagenomic analysis. The conjunctival sac microbiome samples from 28 AC patients and 39 NC patients were collected. The V3-V4 region of 16S rRNA gene high-throughput sequencing was performed on the illumina MiSeq platform. Alpha diversity, beta diversity and the relative abundance at the phylum and genus levels were analyzed using QIIME. Alpha diversity demonstrated by Chao1, Observed_species and PD_whole_tree indexes did not show significant difference between the AC and NC groups, while the Shannon index was higher in the AC group. Beta diversity showed divergent microbiome composition in different groups (p < 0.005). The top five abundant phyla were Firmicutes, Proteobacteria, Actinobacteriota, Bacteroidota and Cyanobacteria in both groups. The top five abundant genera were Bacillus, Staphylococcus, Corynebacterium, Acinetobacter and Ralstonia in the AC group and Acinetobacter, Staphylococcus, Bacillus, Clostridium_sensu_stricto_1, Corynebacterium and Geobacillus in the NC group. The Firmicutes/Bacteroidetes (F/B) ratio at the phylum level was similar between groups (p = 0.144). The Bacillus/Acinetobacter (B/A) ratio at the genus level was higher in the AC group (p = 0.021). The dysbiosis detected in this study might provide further evidence to investigate the mechanism and treatment methods for allergic conjunctivitis.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
We aimed to identify the differences of the conjunctival sac microbiome between Allergic conjunctivitis (AC) patients and healthy subjects using high-throughput 16S rDNA sequencing metagenomic analysis, which could identify a much more diverse microbiota that might not be recovered by conventional culture methods [34]
Conjunctival sac microbiome samples were collected from 28 eyes of patients diagnosed with AC and 39 eyes of patients with healthy ocular surface conditions

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Allergic conjunctivitis (AC) is a common and potentially debilitating ocular surface disease characterized by antigen-specific immunoglobulin E (IgE) and T helper type 2 (Th2). Lymphocyte–mediated type I hypersensitivity [1,2]. The sensitization process begins when antigen-presenting cells in the conjunctiva present antigens to naive T cells. The naive T cells mature into Th1 and Th2 lymphocytes, which secrete cytokines that promote B-cell differentiation and IgE production [3]. When time an allergen is detected, IgE activates mast cells, resulting in the release of preformed mediators promoting vasodilation, vascular permeability, smooth muscle contraction and inflammatory cell recruitment.

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