Altered Th17/Treg Balance And Cytokines In Peripheral Blood Of Patients With Bell's Palsy

BackgroundBell's palsy is an acute,peripheral facial paresis of unknown etiology,possibly initiated by viral infection,autoimmune or vascular ischemia,of which the most likely cause is viral infection.However,some changes in Bell's palsy could not be explained completely by viral infection,and antiviral therapy is not always effective,which means that other mechanisms are involved in.What's more,previous research has shown that impaired immune homeostasis have been implicated in the pathogenesis of Bell,s palsy.T helper 17(Th17)lymphocytes cells have been identified and can mediate tissue inflammation and autoimmune response,while regulatory T(Treg)cells are critical for maintaining self-tolerance and homeostasis.Therefore,in this study,we aimed to evaluate the frequency of Th17 and Treg cells,cytokine secretion,the expression of transcription factors related to Th17 and Treg cells so as to explore the immunological pathogenesis of Bell's palsy.MethodsBlood samples from 20 Bell's palsy patients and 20 health controls were drawn,and the peripheral blood mononuclear cells(PBMCs)were separated and isolated.we detected the frequency of Th17 and Treg cells by flow cytometry and measured the plasma levels of associated cytokines by enzyme-linked immunosorbent assay(ELISA)in Bell's palsy patients.Furthermore,transcription factors related to Th17 or Treg differentiation were quantified by quantitative real-time polymerase chain reaction(qRT-PCR).Then we analyzed the correlations of the cells with clinical manifestations and laboratory examination.ResultsThe proportion of Th17 in the peripheral blood in Bell's palsy patients showed a significant increase than in health controls(p<0.0001).The interleukin-17(IL-17)protein also showed the same trend in plasma(p<0.001).Meanwhile,the expression of signal transducer and activator of transcription 3(STAT3)and retinoic acid-related orphan receptor ?(ROR?t)at messenger RNA(mRNA)level in the PBMCs were significantly increased(p<0.0001).In contrast,compared with the health controls,there was a decrease in the proportion of Treg in the peripheral blood and the expression of forkhead box P3(FoxP3)mRNA in Bell s palsy patients(p=0.0008;p=0.0012).Moreover,Neutrophil-to-lymphocyte ratio(NLR)and Superoxide dismutase(SOD)levels were significantly increased in Bell's palsy patients(p<0.0001;p =0.0002),and Th17 proportion,NLR and body mass index(BMI)were proved to be significantly correlated with disease progression.Then when considering both Thl7 proportion and NLR,they exhibited satisfactory diagnostic performance of prognosis for Bell's palsy patients,with a sensitivity of 87.5%,specificity of 83.3%,and AUC at 0.865(p<0.05).ConclusionsIn summary,our study indicated an impaired regulation of inflammatory state in Bell's palsy patients,possibly mediated through abnormal T-cell homeostasis,which may indicate a potential autoimmune response.The upregulation of Th17 pathways and reduced inhibitory regulation by Treg cells play key roles in this context.These results can be helpful in renewing our knowledge and may shed further light on the treatment of Bell's palsy.