Testing specialized pro-resolving mediators on bacteria-derived inflammation in chronic rhinosinusitis

Abstract

Background and Hypothesis:
Chronic rhinosinusitis (CRS) is defined by chronic tissue inflammation, and prior work in the field implicates activation of the NFκb pathway. This pathway is activated by pattern recognition receptors (PRRs), which recognize molecules associated with pathogens and cellular damage. In CRS subjects, particularly those with nasal polyps, dysregulated pro-resolving processes have been documented. Specialized pro-resolving lipid mediators (SPMs), including lipoxin A₄ and the resolvins, are prime targets for active resolution of the chronic tissue inflammation that defines the disease. We hypothesize that exaggerated pro-inflammatory responses to CRS tissues could be mitigated by application of SPMs in vitro.

Project Methods:
CRS polyp tissue was collected from surgical specimens, and submerged in cell culture conditions with 10 ug/ml lipopolysaccharide (LPS) or lipoteichoic acid (LTA) to mimic bacterial pathogens commonly observed in CRS (i.e., P. aeruginosa or S.aureus). Tissues were treated with 50 nM of SPMs, either lipoxin A₄, resolvin D₁, or resolvin D₂. RNA was isolated from treated tissues. RNA was analyzed with Taqman Microarray NF-kB human pathway RT-PCR panel to evaluate expression of NF-kB-associated genes. In tandem, supernatant was collected for analysis of cytokine and chemokine signaling proteins. Protein assays were performed using the Luminex Multiplex Assay to observe modulation of pro-inflammatory immune signaling molecules

Results:
LPS and LTA exposures demonstrated robust and different pro-inflammatory responses in ex vivo nasal polyp tissue. Treatment with SPMs was able to at least partially reduce NF-kB activation and the associated inflammatory response at a molecular level.

Conclusion:
Inflammation is a complex, temporally precise physiologic process. In chronic inflammatory mucosal diseases such as CRS, repeated acute insults may lead to chronic tissue inflammation. A novel treatment approach leveraging endogenous tissue resolving processes, i.e., SPMs was tested here in vitro and demonstrates potential promise for CRS with nasal polyps.