Immune Complex-Associated Deafness: Preliminary Communication

Causal role of immune cell phenotypes in idiopathic sudden sensorineural hearing loss: a bi-directional Mendelian randomization study

Background

A growing body of evidence suggests that immunological processes have a significant role in developing idiopathic sudden sensorineural hearing loss (SSHL). However, few studies have examined the association between immune cell phenotype and SSHL using Mendelian Randomization (MR).

Methods

The online genome-wide association studies (GWAS) database was used to compile data from GWAS covering 731 immunophenotypes and SSHL. Inverse variance weighted (IVW) analysis was primarily used for MR study, and single nucleotide polymorphisms (SNPs) associated with immunophenotypes served as dependent variables. A sensitivity study and the false discovery rate (FDR) correction were used to examine the MR hypothesis. In addition, the possibility of reverse causality between immunophenotype and SSHL was validated by reverse MR. Reverse MR was analyzed in a manner consistent with forward MR.

Results

After FDR correction and sensitivity analysis, we screened 7 immunophenotypes, including IgD+ CD38dim %lymphocyte (95% CI: 1.0019, 1.0742, p = 3.87 × 10-2, FDR = 1.15 × 10-2); Unsw mem AC (95% CI: 1.004, 1.2522, p = 4.23 × 10-2, FDR = 2.25 × 10-2); CD86+ myeloid DC AC (95% CI: 1.0083, 1.1147, p = 2.24 × 10-2, FDR = 4.27 × 10-2); CD33dim HLA DR- AC (95% CI: 1.0046, 1.0583, p = 2.12 × 10-2, FDR = 4.69 × 10-2); SSC-A on CD8br (95% CI: 1.0028, 1.1461, p = 4.12 × 10-2, FDR = 4.71 × 10-2); CD45RA- CD4+ %T cell (95% CI: 1.0036, 1.0503, p = 2.32 × 10-2, FDR = 4.82 × 10-2); DP (CD4+CD8+) AC (95% CI: 1.011, 1.2091, p = 2.78 × 10-2, FDR = 4.97 × 10-2). There was a strong causal relationship with SSHL onset, and the reliability of the results was verified. Furthermore, the immunological cell profile and SSHL did not appear to be closely associated, as shown by reverse MR analysis.

Conclusion

Our study provides more support for the current hypothesis that immunophenotypes and the pathophysiology of SSHL are closely associated. Further validation is needed to assess the role of these immunophenotypes in SSHL.

Mechanism of Immune Complex—Mediated Inner Ear Diseases

Tissues of the stria vascularis of normal rabbits were collected as cochlear antigen and injected into the foot pad of guinea pigs. The mechanism of development of endolymphatic hydrops was studied by the tracer method. Damage to the capillary endothelium and an increase in vascular permeability were found in the stria vascularis. Therefore, we studied patients with a raised level of immunoglobulin (Ig) G—class circulating immune complexes (CICs). Hearing loss was found in 3 of 22 patients with significantly elevated IgG CIC levels (13.6%). The relationship between inner ear disease and the presence of CIC was considered to be very significant. The possible mechanism of CIC-mediated inner ear diseases is discussed.

Antibodies against a 30 kilodalton cochlear protein and type II and IX collagens in the serum of patients with inner ear diseases

Collagen molecules are major extracellular matrix proteins involved in the development and support of delicate auditory sensory organs. Type II collagen is widely distributed within inner ear tissues, while type IX is found only within the labyrinthine membrane and dense fibers of the tectorial membrane. Antibody specific for type II collagen has been shown to be elevated in some patients with hearing loss due to several presumably autoimmune illnesses (including Meniere's disease, otosclerosis, chronic progressive sensorineural hearing loss, and relapsing polychondritis). Purified human type II and IX collagens and an extract of human cochlear tissue were subjected to isolation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and transferred to nitrocellulose. The sera of 21 patients with inner ear disease were examined for the presence of anticollagen and anticochlear antibodies; the sera were used to probe Western blots of purified human collagens II, IX, and XI, and cochlear protein extract with peroxidase-conjugated goat anti human polyvalent immunoglobulin as the second antibody. Anti-type II collagen antibodies were seen in 12 of 21 (57%) patients, while 13 of 21 (62%) had anti-type IX antibodies detectable by Western blot. A previously unreported 30 kd (probably noncollagen) protein was 21 (62%) had anti-type IX antibodies detectable by Western blot. A previously unreported 30 kd (probably noncollagen) protein was found by SDS-PAGE of human cochlear tissue extracts, with 3 patients, all with Meniere's disease, having antibody activity to this protein detected by Western blot.(ABSTRACT TRUNCATED AT 250 WORDS)

Stria vascularis ultrastructural pathology in the C3H/lpr autoimmune strain mouse: a potential mechanism for immune-related hearing loss

The stria vascularis in the C3H/lpr autoimmune strain mouse was ultrastructurally examined in order to better understand the potential mechanisms by which systemic autoimmune disease affects the ear. The inner ear from C3H/lpr mice before disease onset and C3H/HeJ controls showed no apparent pathology. However, the stria vascularis from older C3H/lpr mice after systemic autoimmune disease onset showed considerable intercellular edema around the stria capillaries and thickening of the capillary basement membrane, compared to controls. These observations suggest that perivascular abnormalities, which are the hallmark of systemic autoimmune diseases, may underlie the stria dysfunction and hearing loss seen in autoimmune diseases in humans.

Mystery deepens--blood on the space-shuttle Discovery's flight STS 26 at zero gravity and some deductions or extrapolations

The second "aggregation of red cells" experiment that was performed on the National Aeronautics and Space Administration's space-shuttle Discovery's flight STS 26 confirms the results that were obtained in 1985; however, some new features have come to light, in particular, the observation of a clot or thrombus which, so far, remains unexplained. An attempt has been made to link observations on the cell-to-cell interaction and blood viscosity under zero gravity to some of the problems that are facing astronauts and to some new dimensions in medical science.