Disturbance in the protein landscape of cochlear perilymph in an Alzheimer's disease mouse model

Hearing loss is a pivotal risk factor for dementia. It has recently emerged that a disruption in the intercommunication between the cochlea and brain is a key process in the initiation and progression of this disease. However, whether the cochlear properties can be influenced by pathological signals associated with dementia remains unclear. In this study, using a mouse model of Alzheimer's disease (AD), we investigated the impacts of the AD-like amyloid β (Aβ) pathology in the brain on the cochlea. Despite little detectable change in the age-related shift of the hearing threshold, we observed quantitative and qualitative alterations in the protein profile in perilymph, an extracellular fluid that fills the path of sound waves in the cochlea. Our findings highlight the potential contribution of Aβ pathology in the brain to the disturbance of cochlear homeostasis.

Lansoprazole Ameliorates Isoniazid-Induced Liver Injury

Isoniazid is a first-line drug in antitubercular therapy. Isoniazid is one of the most commonly used drugs that can cause liver injury or acute liver failure, leading to death or emergency liver transplantation. Therapeutic approaches for the prevention of isoniazid-induced liver injury are yet to be established. In this study, we identified the gene expression signature for isoniazid-induced liver injury using a public transcriptome dataset, focusing on the differences in susceptibility to isoniazid in various mouse strains. We predicted that lansoprazole is a potentially protective drug against isoniazid-induced liver injury using connectivity mapping and an adverse event reporting system. We confirmed the protective effects of lansoprazole against isoniazid-induced liver injury using zebrafish and patients' electronic health records. These results suggest that lansoprazole can ameliorate isoniazid-induced liver injury. The integrative approach used in this study may be applied to identify novel functions of clinical drugs, leading to drug repositioning.

Proton Pump Inhibitors Ameliorate Oxaliplatin-induced Peripheral Neuropathy: Retrospective Analysis of Two Real-world Clinical Databases

BACKGROUND/AIM

Chemotherapy-induced peripheral neuropathy (CIPN) due to oxaliplatin (L-OHP) is a major clinical problem. Effective and safe preventive strategies for CIPN are urgently needed. Although proton pump inhibitors (PPIs) have various off-target effects, their clinical impact on L-OHP-induced CIPN remains unclear. In the present study, we investigated the effects of PPIs on L-OHP-induced CIPN in patients using two real-world clinical databases.

PATIENTS AND METHODS

We retrospectively analyzed the electronic medical records of Osaka University Hospital to examine the effect of PPIs on CIPN development in 217 patients who received XELOX (L-OHP plus capecitabine) therapy for colorectal cancer. In addition, the Japanese Adverse Drug Event Report (JADER) database was used to validate the effects of PPIs on L-OHP-induced CIPN.

RESULTS

The incidences of CIPN (grade ≥2) and discontinuation of L-OHP were significantly lower in patients with PPIs than in those without PPIs. Multivariate analysis showed that concomitant PPIs use was an independent factor that significantly contributed to the prevention of grade ≥2 CIPN (odds ratio=0.054, p<0.001). Kaplan-Meier analysis showed that the time to onset of grade ≥2 CIPN was significantly prolonged in patients with PPIs without affecting the therapeutic efficacy of L-OHP (p=0.004). Moreover, JADER database analyses revealed that the reporting odds ratio of any PPI for L-OHP-induced CIPN was 0.485.

CONCLUSION

Concomitant PPI use ameliorated L-OHP-induced CIPN in patients with colorectal cancer.

Two Loci Contribute to Age-Related Hearing Loss Resistance in the Japanese Wild-Derived Inbred MSM/Ms Mice

An MSM/Ms strain was established using Japanese wild mice, which exhibit resistance to several phenotypes associated with aging, such as obesity, inflammation, and tumorigenesis, compared to common inbred mouse strains. MSM/Ms strain is resistant to age-related hearing loss, and their auditory abilities are sustained for long durations. The age-related hearing loss 3 (ahl3) locus contributes to age-related hearing in MSM/Ms strain. We generated ahl3 congenic strains by transferring a genomic region on chromosome 17 from MSM/Ms mice into C57BL/6J mice. Although C57BL/6J mice develop age-related hearing loss because of the ahl allele of the cadherin 23 gene, the development of middle- to high-frequency hearing loss was significantly delayed in an ahl3 congenic strain. Moreover, the novel age-related hearing loss 10 (ahl10) locus associated with age-related hearing resistance in MSM/Ms strain was mapped to chromosome 12. Although the resistance effects in ahl10 congenic strain were slightly weaker than those in ahl3 congenic strain, slow progression of age-related hearing loss was confirmed in ahl10 congenic strain despite harboring the ahl allele of cadherin 23. These results suggest that causative genes and polymorphisms of the ahl3 and ahl10 loci are important targets for the prevention and treatment of age-related hearing loss.

Repositioning of Lansoprazole as a Protective Agent Against Cisplatin-Induced Ototoxicity

Cisplatin (CDDP) is a well-known chemotherapeutic drug approved for various cancers. However, CDDP accumulates in the inner ear cochlea via organic cation transporter 2 (OCT2) and causes ototoxicity, which is a major clinical limitation. Since lansoprazole (LPZ), a proton pump inhibitor, is known to inhibit OCT2-mediated transport of CDDP, we hypothesized that LPZ might ameliorate CDDP-induced ototoxicity (CIO). To test this hypothesis, we utilized in vivo fluorescence imaging of zebrafish sensory hair cells. The fluorescence signals in hair cells in zebrafish treated with CDDP dose-dependently decreased. Co-treatment with LPZ significantly suppressed the decrease of fluorescence signals in zebrafish treated with CDDP. Knockout of a zebrafish homolog of OCT2 also ameliorated the reduction of fluorescence signals in hair cells in zebrafish treated with CDDP. These in vivo studies suggest that CDDP damages the hair cells of zebrafish through oct2-mediated accumulation and that LPZ protects against CIO, possibly inhibiting the entry of CDDP into the hair cells via oct2. We also evaluated the otoprotective effect of LPZ using a public database containing adverse event reports. The analysis revealed that the incidence rate of CIO was significantly decreased in patients treated with LPZ. We then retrospectively analyzed the medical records of Mie University Hospital to examine the otoprotective effect of LPZ. The incidence rate of ototoxicity was significantly lower in patients co-treated with LPZ compared to those without LPZ. These retrospective findings suggest that LPZ is also protective against CIO in humans. Taken together, co-treatment with LPZ may reduce the risk of CIO.

Involvement of homeobox transcription factor Mohawk in palatogenesis

Palatogenesis is affected by many factors, including gene polymorphisms and exposure to toxic chemicals during sensitive developmental periods. Cleft palate is one of the most common congenital anomalies, and ongoing efforts to elucidate the molecular mechanisms underlying palatogenesis are providing useful insights to reduce the risk of this disorder. To identify novel potential regulators of palatogenesis, we analyzed public transcriptome datasets from a mouse model of cleft palate caused by selective deletion of transforming growth factor-β (TGFβ) receptor type 2 in cranial neural crest cells. We identified the homeobox transcription factor Mohawk (Mkx) as a gene downregulated in the maxilla of TGFβ knockout mice compared with wild-type mice. To examine the role of mkx in palatogenesis, we used CRISPR/Cas9 editing to generate zebrafish with impaired expression of mkxa and mkxb, the zebrafish homologs of Mkx. We found that mkx crispants expressed reduced levels of gli1, a critical transcription factor in the Sonic hedgehog (SHH) signaling pathway that plays an important role in the regulation of palatogenesis. Furthermore, we found that mkxa^-/- zebrafish were more susceptible than mkxa^+/+ zebrafish to the deleterious effects of cyclopamine, an inhibitor of SHH signaling, on upper jaw development. These results suggest that Mkx may be involved in palatogenesis regulated by TGFβ and SHH signaling, and that impairment in Mkx function may be related to the etiology of cleft palate.

Generation of a Transgenic Zebrafish Line for In Vivo Assessment of Hepatic Apoptosis

Hepatic apoptosis is involved in a variety of pathophysiologic conditions in the liver, including hepatitis, steatosis, and drug-induced liver injury. The development of easy-to-perform and reliable in vivo assays would thus greatly enhance the efforts to understand liver diseases and identify associated genes and potential drugs. In this study, we developed a transgenic zebrafish line that was suitable for the assessment of caspase 3 activity in the liver by using in vivo fluorescence imaging. The larvae of transgenic zebrafish dominantly expressed Casper3GR in the liver under control of the promoter of the phosphoenolpyruvate carboxykinase 1 gene. Casper3GR is composed of two fluorescent proteins, tagGFP and tagRFP, which are connected via a peptide linker that can be cleaved by activated caspase 3. Under tagGFP excitation conditions in zebrafish that were exposed to the well-characterized hepatotoxicant isoniazid, we detected increased and decreased fluorescence associated with tagGFP and tagRFP, respectively. This result suggests that isoniazid activates caspase 3 in the zebrafish liver, which digests the linker between tagGFP and tagRFP, resulting in a reduction in the Förster resonance energy transfer to tagRFP upon tagGFP excitation. We also detected isoniazid-induced inhibition of caspase 3 activity in zebrafish that were treated with the hepatoprotectants ursodeoxycholic acid and obeticholic acid. The transgenic zebrafish that were developed in this study could be a powerful tool for identifying both hepatotoxic and hepatoprotective drugs, as well as for analyzing the effects of the genes of interest to hepatic apoptosis.

Risk factors for the development of hypermagnesemia in patients prescribed magnesium oxide: a retrospective cohort study

Background

Magnesium oxide (MgO), an antacid and laxative, is widely used in Japan to treat constipation and peptic ulcers. Because serum Magnesium (Mg) levels are elevated in elderly and/or patients with renal failure, its periodic monitoring is recommended for patients prescribed MgO, in order to prevent MgO-induced hypermagnesemia. However, there is little information regarding the factors contributing to the development of MgO-induced hypermagnesemia. In the present study, we retrospectively investigated the risk factors of hypermagnesemia in patients prescribed MgO.

Methods

Data of 3258 patients hospitalized in Mie University Hospital between October 2015 and September 2017, who were prescribed MgO tablets, were extracted from the electronic medical records. According to the inclusion and exclusion criteria, 320 of the 3258 patients were enrolled in this study. Hypermagnesemia was defined as serum Mg levels ≥2.5 mg/dL (by the Common Terminology Criteria for Adverse Events version 4.0). Uni- and multivariate analyses were performed to identify risk factors for the development of hypermagnesemia in patients prescribed MgO using the following variables: age, estimated glomerular filtration rate, blood urea nitrogen levels, MgO dose, duration of MgO administration, and co-administrated proton pump inhibitors, H₂ blocker (famotidine), vitamin D₃ drugs, and diuretics.

Results

Seventy-five patients out of 320 (23%) developed grade 1 and grade 3 hypermagnesemia, with the occurrence of grade 1 and grade 3 in 62 (19%) and 13 (4%) patients, respectively. Multivariate logistic regression analyses indicated 4 independent risk factors for hypermagnesemia comprising estimated glomerular filtration rate ≤ 55.4 mL/min (odds ratio (OR): 3.105, P = 0.001), blood urea nitrogen ≥22.4 mg/dL (OR: 3.490, P < 0.001), MgO dose ≥1650 mg/day (OR: 1.914, P = 0.039), and duration of MgO administration ≥36 days (OR: 2.198, P = 0.012). The occurrence rate of hypermagnesemia was elevated in accordance with these risk factors.

Conclusions

These results suggest that a periodic monitoring of serum Mg levels is strongly recommended in MgO prescribed patients, especially in those with multiple risk factors for hypermagnesemia. The present findings provide useful information for the safe management of MgO therapy.