The Function And Formation Mechanisms Of Ectopic Lymphoid Tissues In Chronic Rhinosinusitis With Nasal Polpys

Background: Chronic rhinosinusitis(CRS)is a common mucosa chronic inflammatory disorder of nasal cavity and sinuses,its morbidity is increasing in recent years.Since lacking of efficient treatment in consequence of undetermined pathogenesis,many CRS patients need reoperations to control symptoms after first endoscopic sinus surgery or medications.Ig E currently is recognized to be associated with the rise of chronic rhinosinusitis with nasal polyps(CRSw NP).Our previous studies have found that local follicular helper T(Tfh)cells can be induced to support B cells to produce immunoglobulin(Ig)in nasal polyps,and Tfh cells are mainly exist in ectopic lymphoid tissues(e LTs).However,the contribution of e LTs to local Ig hyperproduction in CRSw NP is unclear.Objective: To explore the cellular basis,the formation mechanisms,and the function of e LTs in CRSw NP.Methods: We graded lymphoid aggregations in sinonasal mucosa and studied their structures by histology.The expression of lymphorganogenic factors and molecules required for Ig production was measured by real-time PCR and localized by immunohistochemistry and immunofluorescence.The phenotype of T follicular helper(TFH)cells was analyzed by flow cytometry.Ig levels were quantified by Bio-Plex assay or Immuno CAP system.Nasal tissue explants were challenged ex vivo with Dermatophagoides pteronyssinus group 1(Der p1)and the expression of Iε-Cμ and Iε-Cγ circle transcripts was detected by semi-nested PCR.The stromal cells and B cells were selected by magnetic beads.The protein level of CXCL13/LTα were detected by ELISA after the stromal cells were stimulated by IL-17 A,and B cells were stimulated by CXCL13/LTα.Results: Increased formation of e LTs with germinal center-like structures was discovered in eosinophilic(20.69%)and non-eosinophilic CRSw NP(17.31%)compared to chronic rhinosinusitis without nasal polyps(5.66%)and controls(3.70%).The presence of e LTs was associated with increased expression of lymphorganogenic and inflammatory chemokines and cytokines,as well as their receptors.The expression of molecules required for Ig production,the generation of TFH cells,and the production of Ig E in eosinophilic polyps and Ig G and Ig A in both eosinophilic and non-eosinophilic polyps were predominantly up-regulated in cases with e LTs.After the challenge of Der p1 ex vivo,Iε-Cμ transcript was only detected in eosinophilic polyps with e LTs,but not in those without e LTs and non-eosinophilic polyps.And we found that the duration of disease was longer and the rate of difficult-to-treat NP was higher in NP with e LTs than NP without e LTs.Morevre,Immunofluorescence showed that CXCL13,a key chemotactic factor formed by e LTs,was mainly derived from B cells in NP with e LTs,and was mainly derived from stromal cells in normal sinus mucosa.CXCL13 was increased when stromal cells stimulated by IL-17A;CXCL13/LTα stimulation of B cells led to significantly increased LTα /CXCL13.Conclusion: eLTs may support local Ig production and therefore significantly contribute to the development of CRSw NP.It may be related to difficult-to-treat NP;Excessive expression of IL-17 A may lead to the formation of e LTs.