Bacterial microbiota of the sinuses in CRS.

Background. Chronic rhinosinusitis (CRS) is a heterogeneous disease characterized by persistent sinonasal inflammation and sinus microbiome dysbiosis. The basis of this heterogeneity is poorly understood. We sought to address the hypothesis that a limited number of compositionally distinct pathogenic bacterial microbiota exist in CRS patients and invoke discrete immune responses and clinical phenotypes in CRS patients. Results. Sinus brushings from patients with CRS (n=59) and healthy individuals (n=10) collected during endoscopic sinus surgery were analyzed using 16S rRNA gene sequencing, predicted metagenomics, and RNA profiling of the mucosal immune response. We show that CRS patients cluster into distinct sub-groups (DSI-III), each defined by specific pattern of bacterial co-colonization (PERMANOVA; p=0.001, r2=0.318). Each subgroup was typically dominated by a pathogenic family: Streptococcaceae (DSI), Pseudomonadaceae (DSII), Corynebacteriaceae [DSIII(a)], or Staphylococcaceae [DSIII(b)]. Each pathogenic microbiota was predicted to be functionally distinct (PERMANOVA; p=0.005, r2=0.217) and encode uniquely enriched gene pathways including ansamycin biosynthesis (DSI), tryptophan metabolism (DSII), two-component response [DSIII(b)], and the PPAR-gamma signaling pathway [DSIII(a)]. Each is also associated with significantly distinct host immune responses; DSI, II, and III(b) invoked a variety of pro-inflammatory, TH1 responses, while DSIII(a), which exhibited significantly increased incidence of nasal polyps (Fisher’s Exact; p=0.034, Relative Risk=2.16), primarily induced IL-5 expression (Kruskal Wallis; q=0.045). Conclusions. A large proportion of CRS patient heterogeneity may be explained by the composition of their sinus bacterial microbiota and related host immune response – features which may inform strategies for tailored therapy in this patient population.