Triamcinolone acetonide protects auditory hair cells from 4-hydroxy-2,3-nonenal (HNE) ototoxicity in vitro

Sustained delivery of triamcinolone acetonide from a thermosensitive microemulsion gel system for the treatment of sensorineural hearing loss

Intratympanic administration for the delivery of steroids has been extensively studied but limited because of low permeability of the drug through the row window membrane. Here, to effectively deliver poorly soluble triamcinolone acetonide (TA), microemulsions (ME) were prepared from Capmul MCM (oil), Cremophor RH40 (surfactant), and tetraglycol (cosurfactant) based on solubility studies, emulsifying ability test, and pseudoternary phase diagrams. Microemulsion gel (MEG) was prepared by mixing TA-ME with a poloxamer hydrogel base. The physicochemical properties of ME and MEG formulations were characterized, and the toxicity and oto-protective effectiveness were evaluated in vitro and in vivo. The ME-3 formulation showed a small droplet size (16.5 ± 0.2 nm), narrow PDI (0.067 ± 0.041), and enhanced TA solubility (2619.7 ± 57.6 μg/g). The optimized MEG demonstrated temperature-dependent gelation with a gelation time of 208 ± 10 sec at 37 °C. Slow degradation of the gel matrix sustained release of TA from MEG compared to the ME formulation. Both TA-ME and TA-MEG were found to be nontoxic to NIH3T3 cells at the test concentrations (0 to 5 µg/mL), and biocompatible after intratympanic administration to mice. The incorporation of ME into thermosensitive hydrogels prolonged retention of TA at the site of administration until 6 days. As a consequence, the enhanced drug absorption into the cochlea in TA-MEG group (approximately 2 times higher than other groups) protected hair cells, spiral ganglion neurons, and stria vascular cells from cisplatin-induced damage. Therefore, this injectable TA-loaded MEG is an effective and safe vehicle for the sustained delivery of triamcinolone acetonide into the inner ear.

Definite therapy of mixed infection alleviates refractory dilemma of adult chronic suppurative otitis media

The characteristics, risk factors, microbial distributions and effective treatment regimens for Chronic suppurative otitis media (CSOM) patients intractable to empirical therapy were analyzed. Adult CSOM patients of China Medical University Hospital from 2018 to 2020 were included. Subjects of refractory and non-refractory groups were investigated for characteristics of age, sex, nation, comorbidities, otomycosis, and associated complications. Risk factors, microbiology distributions, and treatment regimens were analyzed. Twenty-six refractory patients (55.0 ± 17.7 years) and 66 non-refractory patients (54.1 ± 13.7 years) were studied. A significantly higher rate of otomycosis and CSOM complications was observed in refractory group than in non-refractory one (73.1% vs. 36.4%; p = 0.002; 57.7% vs. 10.6%, p < 0.001, respectively). Multivariate analysis revealed atopic diathesis (p = 0.048), otomycosis (p = 0.003) and CSOM complications (p < 0.001) were risk factors of refractory CSOM. Coagulase-negative staphylococci (CoNS) and methicillin-resistant Staphylococcus aureus (MRSA) were the prevailing pathogens. Patients of refractory group tented to have higher rates of mixed infection (42.9%% vs. 23.7%) and significantly more included fungal pathogen (19.0% vs. 2.6%; p = 0.049) than those of non-refractory cohort. Topical treatment of fungus significantly improved outcome of refractory CSOM. Atopic diathesis, otomycosis, and CSOM-associated complications were risk factors of refractory CSOM. Systemic and local treatment to possible drug-resistant pathogens, likely CoNS and fungus, possible improves recalcitrant CSOM. Correspondingly, early identification of CSOM complications, routine culture and susceptibility testing and treatment of resistant bacteria and fungus are key elements to the successful management of adult CSOM.

Preclinical evaluation of thermoreversible triamcinolone acetonide hydrogels for drug delivery to the inner ear

Intratympanic glucocorticoid therapy aims to reduce the side effects associated with systemic long-time therapy of inner ear diseases or traumata after cochlear implantation. For that purpose, thermoreversible hydrogels being fluid at room temperature but solid at body temperature are known to be appropriate drug delivery systems. In this work, the two key parameters sol–gel transition time and temperature of Poloxamer 407 (POX 407) based hydrogels containing oto-compatible micronized triamcinolone acetonide (TAAc) were evaluated by rheological experiments varying the concentrations of the different compounds. A 20% POX 407 hydrogel in PBS containing 30% TAAc emerged as the most appropriate formulation. Oscillation–rotation–oscillation studies at two temperature levels were found to be an useful in-vitro test system for the hydrogel which revealed sufficient storage stability at 4 °C, injectability of the sol, solidification within 20 s at body temperature and persistent stiffness indicating prolonged adhesion at the round window membrane. According to the in-vitro release studies using the Transwell™ system, absorption of the poor water soluble TAAc is partly due to the low amount of dissolved drug but predominantly due to micellar transport resulting in a cumulative release of 262.6 ± 13.4 μg TAAc within one week followed by a sustained release of 193.1 ± 8.3 μg TAAc within the next three weeks. Thus, the formation of POX 407 micelles is the basis not only for gel formation but also absorptivity of TAAc. All in all, fine tuned rheological experiments and absorption studies emerged as useful tools for preclinical evaluation of intratympanally administered hydrogels.

Sustained release of triamcinolone acetonide from an intratympanically applied hydrogel designed for the delivery of high glucocorticoid doses

The pharmacokinetic properties and tolerability of a triamcinolone acetonide poloxamer 407 hydrogel for intratympanic application were investigated in a guinea pig model. Evaluation of in vivo release kinetics showed very high initial perilymph drug levels, with clinically relevant levels present for a minimum of 10 days. Assessment of auditory brainstem response thresholds showed a minimal, delayed and transient threshold shift, which was apparent on day 3 and resolved by day 10. No relevant histological changes of the middle and inner ear structures were noted, and hair cell counts showed no significant differences between treated and untreated ears. Thus, the triamcinolone-acetonide-loaded poloxamer 407 hydrogel is an effective vehicle for sustained high-dose inner ear glucocorticoid delivery.

Regeneration of mammalian cochlear and vestibular hair cells through Hes1/Hes5 modulation with siRNA

The Notch pathway is a cell signaling pathway determining initial specification and subsequent cell fate in the inner ear. Previous studies have suggested that new hair cells (HCs) can be regenerated in the inner ear by manipulating the Notch pathway. In the present study, delivery of siRNA to Hes1 and Hes5 using a transfection reagent or siRNA to Hes1 encapsulated within poly(lactide-co-glycolide acid) (PLGA) nanoparticles increased HC numbers in non-toxin treated organotypic cultures of cochleae and maculae of postnatal day 3 mouse pups. An increase in HCs was also observed in cultured cochleae and maculae of mouse pups pre-conditioned with a HC toxin (4-hydroxy-2-nonenal or neomycin) and then treated with the various siRNA formulations. Treating cochleae with siRNA to Hes1 associated with a transfection reagent or siRNA to Hes1 delivered by PLGA nanoparticles decreased Hes1 mRNA and up-regulated Atoh1 mRNA expression allowing supporting cells (SCs) to acquire a HC fate. Experiments using cochleae and maculae of p27(kip1)/-GFP transgenic mouse pups demonstrated that newly generated HCs trans-differentiated from SCs. Furthermore, PLGA nanoparticles are non-toxic to inner ear tissue, readily taken up by cells within the tissue of interest, and present a synthetic delivery system that is a safe alternative to viral vectors. These results indicate that when delivered using a suitable vehicle, Hes siRNAs are potential therapeutic molecules that may have the capacity to regenerate new HCs in the inner ear and possibly restore human hearing and balance function.

Triamcinolone acetonide prevents oxidative stress-induced tight junction disruption of retinal pigment epithelial cells

PURPOSE

Oxidative stress is known to disrupt the integrity of retinal pigment epithelium (RPE) tight junctions. The goal of this study is to evaluate the effect of triamcinolone acetonide (TA) on the junctional integrity of RPE under oxidative stress and to identify the underlying mechanisms.

METHODS

Second passage porcine RPE cells were cultured on 6-well membrane inserts until 4 weeks after reaching confluence. Cells were incubated with TA (10(-5) M) for 30 min. FITC-containing medium was added to the upper chamber (cell's apical side). The cells were then challenged with 1 mM Hydrogen Peroxide (H(2)O(2)). After 5 h, the fluorescence intensity of the medium from lower chamber (cell's basolateral side) was measured using a fluorescence spectrofluorophotometer. This transepithelial flux of FITC-dextran was measured until the 21st day. The immunolocalization of occludin and F-actin was examined with fluorescence microscope. Reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio was determined by a colorimetric assay kit.

RESULTS

Non-lethal oxidative stress by H(2)O(2) increased transepithelial flux of FITC-dextran significantly. TA inhibited this increase and preserved the lower flux through the whole experimental period. This permeability change by H(2)O(2) was reversible and recovered to the normal level within 3 weeks. In immunohistological study, H(2)O(2) reduced linear occludin staining at the cell border and increased actin stress fibers. TA prevented H(2)O(2)-induced disruption of junctional assembly of occludin and F-actin. Glutathione assay demonstrated that intracellular GSH/GSSG ratio decreased significantly with H(2)O(2), while TA preserved this ratio by up-regulating GSH synthesis.

CONCLUSIONS

TA has a protective effect against oxidative stress-induced disruption of RPE tight junction by preserving cellular redox state.

Ciprofloxacin 0.3%/dexamethasone 0.1% sterile otic suspension for the topical treatment of ear infections: a review of the literature

The objective of this article is to review the literature related to ciprofloxacin 0.3% and dexamethasone 0.1% sterile otic suspension. A systematic literature search utilizing Medline was conducted to identify peer-reviewed articles related to safety and efficacy. A total of 47 publications were identified and reviewed herein. The literature supports the use of antibiotic/antiiflammatory combination ear drops in the treatment of both acute otitis externa and acute otitis media in pediatric patients with tympanostomy tubes. Ciprofloxacin/dexamethasone has been demonstrated as safe and effective with regard to clinical cures and microbiological eradication of pathogens in either disease with low treatment failure rates. Additionally, the literature also provides clear evidence for the contribution of dexamethasone when added to ciprofloxacin for the topical treatment of ear infections.

Blocking c-Jun-N-terminal kinase signaling can prevent hearing loss induced by both electrode insertion trauma and neomycin ototoxicity

Neomycin ototoxicity and electrode insertion trauma both involve activation of the mitogen activated protein kinase (MAPK)/c-Jun-N-terminal kinase (JNK) cell death signal cascade. This article discusses mechanisms of cell death on a cell biology level (e.g. necrosis and apoptosis) and proposes the blocking of JNK signaling as a therapeutic approach for preventing the development of a permanent hearing loss that can be initiated by either neomycin ototoxicity or electrode insertion trauma. Blocking of JNK molecules incorporates the use of a peptide inhibitor (i.e. D-JNKI-1), which is specific for all three isoforms of JNK and has been demonstrated to prevent loss of hearing following either electrode insertion trauma or loss of both hearing and hair cells following exposure to an ototoxic level of neomycin. We present previously unpublished results that control for the effect of perfusate washout of aminoglycoside antibiotic by perfusion of the scala tympani with an inactive form of D-JNKI-1 peptide, i.e. JNKI-1(mut) peptide, which was not presented in the original J. Neurosci. article that tested locally delivered D-JNKI-1 peptide against both noise- and neomycin-induced hearing loss (i.e. Wang, J., Van De Water, T.R., Bonny, C., de Ribaupierre, F., Puel, J.L., Zine, A. 2003a. A peptide inhibitor of c-Jun N-terminal kinase protects against both aminoglycoside and acoustic trauma-induced auditory hair cell death and hearing loss. J. Neurosci. 23, 8596-8607). D-JNKI-1 is a cell permeable peptide that blocks JNK signaling at the level of the three JNK molecular isoforms, which when blocked prevents the increases in hearing thresholds and the loss of auditory hair cells. This unique therapeutic approach may have clinical application for preventing: (1) hearing loss caused by neomycin ototoxicity; and (2) the progressive component of electrode insertion trauma-induced hearing loss.