The Etiology and Pathogenesis of Chronic Rhinosinusitis: a Review of Current Hypotheses

Abstract

Chronic rhinosinusitis (CRS) is a broad clinical syndrome that is characterized by prolonged mucosal inflammation of the nose and paranasal sinuses, and is typically divided into two subtypes based on the presence or absence of nasal polyps. The etiology and pathogenesis of both forms remain areas of active research. Over the last 15 years, a number of hypotheses have been proposed to explain all or part of the clinical CRS spectrum. These hypotheses reflect the concept that CRS results from a dysfunctional interplay between individual host characteristics and factors exogenous to the host. Six broad theories on CRS etiology and pathogenesis are discussed as follows: (1) the “fungal hypothesis,” (2) the “superantigen hypothesis,” (3) the “biofilm hypothesis,” and (4) the “microbiome hypothesis,” all of which emphasize key environmental factors, and (5) the “eicosanoid hypothesis” and (6) the “immune barrier hypothesis,” which describe specific host factors. These theories are reviewed, and the evidence supporting them is critically appraised.

Chronic rhinosinusitis: a microbiome in dysbiosis and the search for alternative treatment options

“…For instance, an acute viral infection is the cause for many cases of sinus microbiome disturbance, but this is a short-term disturbance 1,6 . Also, while fungi are not considered primary etiologic agents of CRS, allergies to some fungi can result in a distinct condition with similar symptoms as CRS called Allergic Fungal Rhinosinusitis 5 . However, the group of microorganisms that are the biggest players in CRS are bacteria 1,5 .…”

“…Also, while fungi are not considered primary etiologic agents of CRS, allergies to some fungi can result in a distinct condition with similar symptoms as CRS called Allergic Fungal Rhinosinusitis 5 . However, the group of microorganisms that are the biggest players in CRS are bacteria 1,5 .…”

“…The commensal microbes form a symbiotic relationship with the host, such as by forming a barrier against incoming external pathogens 8 . An imbalance of the sinus microbiome -termed microbiome dysbiosis -is seen in many cases of CRS, as seen by an overabundance of opportunistic pathogens and loss of key commensals 5,6,8,9 . The immune system is then activated due to pathogen invasion through epithelial tight Hot Topic junctions and release of various immunostimulatory molecules, thus resulting in inflammation 1,5 (Figure 1).…”

“…The bacterial taxa presented here are a few of the commensal and pathogenic species that have been implicated in CRS disease progression. This figure is adapted from the information in the following references 5,6,[8][9][10][11][12][13][14][15][16] .…”

“…pollutants or smoking) and host factors (e.g. the immune system and underlying diseases) 5 . This article explores the role that bacteria play in CRS by examining recent research suggesting that disturbances to the sinus microbiome are involved in CRS pathophysiology.…”