Kuang-Chuan Cheng

Structural analysis of the mouse T-cell receptor Tcra V2 subfamily.

Cosmid clones containing T-cell receptor Tcra V2 subfamily gene segments have been isolated from a BALB/c cosmid library and subjected to DNA sequence analysis. The V gene segments in the Tcra V2 subfamily differ from each other by 3%–7% at the nucleotide level and 5%–16% at the amino acid level. T-cell receptor Tcra V2 gene segment polymorphisms have been identified in the B10.PL and PL/J mouse strains with a Tcra V2 subfamily-specific probe. These V gene segment polymorphisms may cause the differential Tcra V gene usage in induced experimental allergic encephalomyelitis between B10.PL and PL/J mice.

Proto-Oncogene Raf-1 as an Autoantigen in Meniere's Disease

The 28 kd protein extracted from the guinea pig inner ear membranous fraction, which reacted with sera from patients with Menieres disease, has been subjected to microsequencing. Nineteen amino acids were obtained (IVQQFGFQRRASDDGKLTQ). A protein data bank search showed that this sequence corresponded to residues 41 to 60 of human Raf-1 protein. Sera from 16 of 27 patients with Menieres disease showed reactivity to the recombinant purified glutathione-S-transferase–Raf-1 protein. These results support the hypothesis that a subgroup of patients who suffer from Menieres disease, as well as some other kinds of autoimmune inner ear diseases, have an autoantibody against Raf-1 protein.

Murine model of autoimmune hearing loss induced by myelin protein P0

Myelin protein P0 has been identified as an autoantigen in inner ear diseases. In order to study autoimmune hearing loss, we performed brain stem auditory-evoked potential (BAEP) studies on P0-sensitized mice. Two P0-sensitized mice showed hunched posture, poor coat, loss of body weight, and abnormal walking with a waddling gait. About 25% of the P0-sensitized mice developed hearing loss. In the BAEP study, peak latencies of waves I, III, and V and the interpeak latency I-III were prolonged in the P0-sensitized hearing loss group of mice. Hearing thresholds were elevated in this group of mice in comparison with the control mice. Inflammatory cell infiltration was observed in the cochlear nerve region, and a reduced number of spiral ganglion cells was also detected. These results suggest that P0-sensitized mice are a useful model for studying autoimmune inflammation of the peripheral portion of the auditory system.

Successful Prevention of Retrocochlear Hearing Loss in Murine Experimental Allergic Encephalomyelitis with T Cell Receptor Vβ8–Specific Antibody

Experimental allergic encephalomyelitis is an animal model of a T cell—mediated autoimmune disease — for example, multiple sclerosis. We demonstrated that mice with experimental allergic encephalomyelitis developed retrocochlear hearing loss, and that the lesion of the auditory pathway might be related to T cell receptor Vß8–expressing T cells. To investigate whether anti-Vß8 antibody could prevent hearing loss, we carried out brain stem auditory evoked potential testing, histologic examinations, and flow cytometry in antibody-treated and control myelin basic protein—immunized B10.PL mice. The antibody was administered just before immunization of myelin basic protein. The disease incidence and severity were significantly reduced in the mice injected with the antibody. The results of brain stem auditory evoked potential testing, histologic examinations, and flow cytometry indicated that the depletion of Vß8-expressing T cells brings the prevention of hearing loss, as well as prevention of other neurologic deficits. The development of T cell receptor—specific antibody therapy might help treat retrocochlear hearing loss in multiple sclerosis.

Brain Stem Auditory-Evoked Potentials of Mice with Experimental Allergic Encephalomyelitis

Experimental allergic encephalomyelitis (EAE) is an experimental model for multiple sclerosis. In order to study autoimmune retrocochlear hearing loss, we performed brain stem auditory-evoked potential (BAEP) studies on EAE mice. The EAE was induced in B 10.PL and (PL/J x SJL)F1 mice. In the BAEP study, all of the peak and interpeak latencies were prolonged significantly in the diseased mice. Hearing thresholds were slightly elevated in the immunized mice during the acute phase. Inflammatory and phagocytic cell infiltration, demyelination, and Vβ8.1, 8.2 T-cell receptor-positive cells were observed in the cochlear nerves or their proximity by histologic study. It is suggested that immunologic reactions identified with EAE also occurred in the cochlear nerve, and that these reactions were responsible for the hearing problems. It appears that EAE is a useful model system for studying autoimmune insults on the neural portion of the auditory system.

TCRV and TCRJ gene usage in MBP responding T cells from (B10.PL×PL/J)F1 mice is biased towards that of B10.PL mice

We analyzed myelin basic protein (MBP) specific T cell hybridoma clones from (B10.PL x PL/J)F1 mice. MBP-reacting T cell hybridomas from F1 mice preferentially expressed B10.PL TcraV2.3 (53%) and B10.PL TcraV4.2 (13%) with minor expression of TcraV4.4 (13%) gene segments. A dominant expression of TcrbV8.2 (73%) accompanying with TcrbV8.1 (20%) and TcrbV13 (7%) gene segments have been identified in these MBP-reacting T cell hybridomas from F1 mice. There was less restrictive but non-random usage of the TcraJ and TcrbJ gene segments. Overall, the MBP-reacting T cell hybridomas from (B10.PL x PL/J)F1 mice were dominated by the MBP-reacting T cell pattern seen in B10.PL mice.