Prevalence and clinical significance of anticardiolipin, anti-β₂-glycoprotein-1, and anti-heat shock protein-70 autoantibodies in sudden sensorineural hearing loss

Sudden sensorineural hearing loss (SSNHL) is frequently classified as 'idiopathic' since the causative factor responsible for its onset is not identified in most cases. In the present study, we determined whether SSNHL is clinically associated with serum anti-heat shock protein-70 (anti-HSP70) and antiphospholipids (anti-PLs) autoantibodies and whether these autoantibodies have an impact on the prognosis of SSNHL. Sera from 63 patients with SSNHL were screened prospectively for the presence of anti-HSP70 and anti-PLs autoantibodies by an enzyme-linked immunosorbent assay test. Anti-PLs antibodies in this study consisted of anticardiolipin, and anti-β₂- glycoprotein-1 antibodies. Serum was assayed for anti-HSP70 IgG antibodies using recombinant human HSP70. Demographic, clinical, and audiometric variables were analyzed to find the possible role of serum autoantibodies in SSNHL patients. Sixteen patients (25.4%) had demonstrable anti-HSP70 antibodies in serum. Twenty-one patients (33.3%) showed a positive result for at least one isotype (IgM or IgG) of anti-PLs. In 19% of the patients, anti-HSP70 and anti-PLs antibodies were positive in two combinations. A statistically significant association was found between anti-HSP70 antibodies and the Siegel recovery grade subgroup. SSNHL patients who were positive for anti-HSP70 antibodies showed a significantly higher rate of complete recovery and incomplete but partial recovery than SSNHL patients without anti-HSP70 antibodies (p = 0.0496). Statistically significant association was found between total anticardiolipin, total anti-β₂-glycoprotein-1, total anti-PLs, and anti-PLs in combination with anti-HSP70 antibodies and age (p = 0.0229). The detection of autoantibodies to HSP70 and PLs offers a pliable explanation for the immune-mediated mechanism of SSNHL. The present study confirms and supports previous studies regarding the association between anti-HSP70 and anti-PLs antibodies with SSNHL, and is the first to identify a positive association between anti-HSP70 antibodies and a positive outcome of SSNHL. Further studies are necessary in order to identify and further clarify the immunologic role of the presence of autoantibodies and their impact on the prognosis of SSNHL.