Inflammatory and immune responses in the cochlea: potential therapeutic targets for sensorineural hearing loss

The inner ear was previously assumed to be an immune-privileged organ due to the existence of its tight junction-based blood-labyrinth barrier. However, studies performed during the past decade revealed that the mesenchymal region of the cochlea, including its lateral wall, is a common site of inflammation. Neutrophils do not enter this region, which is consistent with the old dogma; however, bone marrow-derived resident macrophages are always present in the spiral ligament of the lateral wall and are activated in response to various types of insults, including noise exposure, ischemia, mitochondrial damage and surgical stress. Recent studies have also revealed another type of immune cell, called perivascular melanocyte-like macrophages (PVM/Ms), in the stria vascularis. These dedicated antigen-presenting cells also control vascular contraction and permeability. This review discusses a series of reports regarding inflammatory/immune cells in the cochlear lateral wall, the pathways involved in cochlear damage and their potential as therapeutic targets

Mapping of Notch signaling in the developing organ of Corti in common marmosets

IntroductionThe well-regulated development of the sensory epithelium is essential for hearing. This process involves the specification of a pro-sensory epithelium containing common progenitors that differentiate into hair and supporting cells. Notch signaling is one of the most critical pathways during these processes, and its modification is thought to be a feasible approach for treating hearing loss. Despite interspecies differences between rodents and primates or humans, most of our current knowledge regarding cochlear development has been obtained from rodent models.MethodsWe therefore examined and mapped the expression patterns of Notch signal components in the developing cochlea of the common marmoset (Callithrix jacchus), a small monkey species native to the New World, a primate model animal.ResultsIn contrast to the preserved expression patterns of the Notch signaling components in the hair cell differentiation between primates and rodents, we unveiled relatively large interspecies differences during the maturation of supporting cells.DiscussionThis improved knowledge of Notch signaling during primate cochlear development will facilitate the development of future regenerative therapies

Evidence of mature adipocyte proliferation regulated by proliferin

Despite much research, whether mature adipocytes proliferate remains controversial. Here, we examined 5-bromo-2′-deoxyuridine (BrdU)-labelling of mature adipocytes. Although BrdU incorporation into subcutaneous adipocytes was less than that in visceral adipocytes, pioglitazone (Pio) treatment increased BrdU incorporation in subcutaneous, but not visceral, adipocytes in rats. Fully differentiated 3T3-L1 adipocytes exhibited an increase in cell number and BrdU incorporation with time, with this increase enhanced by Pio treatment. We therefore screened for genes that encode growth factors regulated by Pio, and selected proliferin (PLF). Both gene silencing of PLF by small interfering RNA and treatment with anti-PLF antibody suppressed proliferation in 3T3-L1 adipocytes. In adipocytes isolated from Pio-treated rats, the tissue-specific pattern of PLF expression was similar to that of BrdU incorporation. Administration of an anti-PLF antibody to mice reduced BrdU incorporation into adipocytes. Mature adipocytes thus have the ability to replicate, and this proliferation is positively regulated by PLF

Relationship between Response to Interferon Therapy and Detection of Hepatitis C Virus RNA by Differential Flotation Centrifugation

We purified an apurinic/apyrimidinic (AP) endonuclease from mouse ascites sarcoma (SR-C3H/He) cells. The enzyme showed nicking activity on acid-depurinated DNA but not on untreated, intact DNA. It also showed priming activity for DNA polymerase on both acid-depurinated and bleomycin-damaged DNA. The priming activity on bleomycin-damaged DNA was two times higher than that on an acid-depurinated DNA. The enzymatic properties indicate that the enzyme is a class II AP endonuclease having DNA 3' repair diesterase activity. The purified enzyme has a molecular weight of 39,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The optimal pH for AP endonuclease activity was 8.0 in 50 mM Tris-HCl buffer. The AP endonuclease activity depended on divalent cation such as Mg2+ and Co2+ ions, and was inhibited by 2 mM EDTA with no addition of the divalent cation. An appropriate concentration of sodium or potassium salt stimulated the activity. Partial digestion of the AP endonuclease with Staphylococcus aureus V8 protease produced 4 major peptide fragments which may be used for protein sequencing.</p

Relationship of serum markers of hepatitis B and C virus replication in coinfected patients.

To evaluate viral interference between hepatitis B and C, we studied coinfected patients serologically and molecular biologically. Twenty-seven patients positive for hepatitis B surface antigen (HBsAg) and anti-hepatitis C virus (HCV) antibody, were classified into Groups BC-L and BC-H according to DNA-polymerase activity (less or greater than 100 cpm, respectively). Patients with hepatitis B or C alone were also enrolled as controls. HCV-RNA was detected more often in Group BC-L than in Group BC-H. Genotype 1b of HCV was determined in 75% of Group BC-H, 87.5% of Group BC-L, and 70.7% of hepatitis C-only patients. Activity of DNA-polymerase in coinfected patients was lower in patients positive for HCV-RNA as compared with those negative. HBsAg titers tended to be lower in coinfected patients than in patients with hepatitis B virus (HBV) alone. In conclusion, in coinfection, HBV may suppress the replication of HCV and HCV appears to reduce the expression of HBsAg and probably suppresses HBV replication.&#60;/P&#62;</p

Cold activation of serum complement in patients with chronic hepatitis C: study on activating pathway and involvement of IgG.

It has been documented that the serum complement activities measured by hemolytic assay (CH50) are decreased after storage of sera at a low temperature in some patients with chronic hepatitis C. However, the mechanism of this phenomenon has not been identified yet. Here, we tried to elucidate factors involved in the cold activation of complement (CAC). To clarify what pathway is activated in CAC, we measured complement cleavage products after cold storage of sera. C4d increased significantly after 12 h-storage at cold temperatures in 5 CAC (+) sera compared with 5 CAC (-) (P &#60; 0.01) and 3 control sera (P &#60; 0.05), while Bb did not increase in any of the groups. In order to determine whether IgG or IgG complex is necessary for CAC, 8 CAC (+) sera were incubated with Protein G Sepharose gel beads, and all of them retained hemolytic activities to some extent after cold storage. Column chromatography through Superose 6HR of CAC-positive serum identified the fractions containing molecules that induced CAC in normal serum, which were depleted by treatment with protein G Sepharose. In conclusion, CAC in hepatitis C seems to occur via a classical or lectin pathway, and the IgG complex produced in hepatitis C virus infection may be an important factor in inducing CAC, a common extrahepatic manifestation of hepatitis C.</p

Mutations in the hepatitis B virus preS2 region and abrogated receptor activity for polymerized human albumin.

The preS2 region of the hepatitis B virus (HBV) has been reported to have human polymerized albumin receptor (PAR) activity, which correlates with viral replication. Here, we studied the genomic sequence of the preS region from rare patients lacking PAR activity, despite active viral replication. PAR and DNA polymerase activity was identified in 178 HBe antigen-positive HBV carriers, and a significant correlation between 2 markers was shown, except in 2 hepatitis patients lacking PAR activity. Nucleotide sequences of the preS region of HBV from both patients were examined by direct sequencing of PCR products. In one patient, a 45-base deletion was found to overlap half of the putative polymerized human albumin binding site in the preS2 region. In the other patient, a point mutation at the first nucleotide of the start codon of the preS2 region of HBV was found. There was no such genomic change in the 3 control HBV sequences. These results indicate that the preS2 region is necessary for binding of polymerized human albumin, and this is the first report of naturally existing mutant virus with no or low PAR activity.</p

Function of vascular endothelium and vasomotor nerve in atherosclerotic animals

科学研究費補助金研究成果報告書研究種目: 基盤研究(C)研究期間: 2000～2001課題番号: 12672213研究代表者: 安屋敷 和秀（滋賀医科大学・医学部・助教授）研究分担者: 岡村 富夫（滋賀医科大学・医学部・教授）研究分担者: 藤岡 秀行（滋賀医科大学・医学部・助手

Analyses of projection route of nitroxidergic nerve and its transmission mechanism

科学研究費補助金研究成果報告書研究種目: 基盤研究(B)研究期間: 1999～2001課題番号: 11470023研究代表者: 岡村 富夫（滋賀医科大学・医学部・教授）研究分担者: 安屋敷 和秀（滋賀医科大学・医学部・助教授）研究分担者: 藤岡 秀行（滋賀医科大学・医学部・助手）研究協力者: 戸田 昇（滋賀医科大学・名誉教授