1. INTRODUCTION
Allergic diseases have dramatically risen over the last few decades.1 Allergic conjunctivitis (AC) is one of the most common ocular surface disorders that encompasses a spectrum of diseases featured by antigen-specific immunoglobulin E (IgE) and T helper type 2 (Th2) lymphocyte-mediated hypersensitivity responses.2 Among different types of AC, seasonal allergic conjunctivitis (SAC) and perennial allergic conjunctivitis (PAC) represent the majority of cases. SAC and PAC share similar clinical feature and pathologic process in which type I hypersensitivity plays a key role. Vernal keratoconjunctivitis (VKC) and atopic keratoconjunctivitis (AKC) are more severe than SAC/PAC and can ultimately lead to vision loss. In contrast to SAC/PAC, type IV hypersensitivity is the major mechanism of VKC/AKC.
Increasing evidence shows that the microbiome of skin, gut, and airways play an important role in allergic diseases like atopic dermatitis, food allergies, and asthma.3,4 For instance,Staphylococcus aureus exacerbates atopic dermatitis by inducing skin inflammation and weakening the skin barrier.5Colonization of Moraxella , Streptococcus , andHaemophilus in the airways are associated with increased risk of asthma possibly by promoting viral respiratory tract infections.6 Similar to skin and other mucosal surfaces, conjunctiva is colonized with a variety of microbes.7–10 However, the association between the conjunctival microbiome dysbiosis and ocular allergy remains unexplored.
Here we surveyed the conjunctival metagenomes of 39 patients with various types of AC (SAC/PAC and VKC) and 48 healthy controls using metagenomic shotgun sequencing. We characterized the microbial dysbiosis associated with AC and identified distinct microbial signatures of VKC and SAC/PAC. These findings offer new insight into the prevention and treatment of ocular allergy.