Heat shock protein 70 and cellular disturbances in cochlear cisplatin ototoxicity model

Evaluation of histologic, antiapoptotic and antioxidant effects of melatonin against the acute ocular toxicity of Cisplatin

This study aimed to investigate the protective effect of melatonin against the acute toxicity of cisplatin in ocular tissues. The eyes of 40 rats were divided into 4 groups: Control group (10 rats), Melatonin (Mel) group (10 rats), Cisplatin (Cis) group (10 rats), Melatonin (Mel) + Cisplatin (Cis) group (10 rats). Retina, cornea, and ciliary body tissues were examined after hematoxylin-eosin staining of sections obtained from the eyes and were scored for disorganization and degeneration. Apoptotic cells were counted for the retina, cornea, and ciliary body with the TUNEL (Terminal deoxynucleotidyl transferase dUTP nick end labeling) method. The total antioxidant status (TAS) / total oxidant status (TOS) of homogenized eye tissues were measured. While apoptotic cells were found to increase in the cornea of the Cisplatin (Cis) group, no difference was found regarding the retina and ciliary body cell count. An increased number of apoptotic cells in the cornea of the Cis group was found while there was a decrease in the group where Cisplatin and Melatonin were administered together (Mel+Cis group). There was no statistically significant difference amongst groups for TOS or TAS. Melatonin had a partial protective effect against histological damage.

Association between polymorphisms of heat-shock protein 70 genes and noise-induced hearing loss: A meta-analysis

Background

Recent studies have evaluated the associations between polymorphisms of the heat-shock protein 70 (HSP70) encoding genes and noise-induced hearing loss (NIHL). However, the conclusions of these studies are conflicting. The objective of this meta-analysis was to clarify the association between all known polymorphisms of HSP70 genetic loci and susceptibility to NIHL, based on existing reports.

Methods

We conducted a meta-analysis of the association between Hsp70 polymorphisms (rs1043618, rs1061581, rs2075800, rs2227956, and rs2763979) and NIHL risk in both Chinese and Caucasian males. All statistical analysis was done with was conducted using the “meta” package (version 4.6–0) of R version 3.3.2 and RStudio version 1.0.44. Online databases were searched for eligible case-control studies on February 13, 2017. The odds ratio (OR), 95% confidence interval (CI), and P value were calculated using Mantel-Haenszel statistics under a random- or fixed-effect model.

Results

A total of five studies, reported via four articles from online databases, were included in our meta-analysis. For rs1061581 (from three studies), a significant association was detected in the allele model, homozygote model, and dominant model (G versus A: OR (95% CI) = 1.32(1.05–1.67), GG versus AA: OR (95% CI) = 1.93(1.1–3.36), GG + AG versus AA: OR (95% CI) = 1.45(1.05–2.02)), but not in the heterozygote model or the recessive model. For rs1043618 (from five studies), rs2075800 (from two studies), rs2227956 (from four studies), rs2763979 (from two studies), no significant association was found for any genetic model. After subgroup analyses by ethnicity, significant associations were observed for the allele model, heterozygote model, and dominant model for rs1061581 and any genetic model for rs2227956 in Caucasians.

Conclusions

The rs1043618, rs2075800, and rs2763979 polymorphisms were not found to be associated with susceptibility to NIHL; however, the rs1061581 and rs2227956 polymorphisms were significantly associated with NIHL in Caucasian males.

Otoprotective properties of 6α-methylprednisolone-loaded nanoparticles against cisplatin: In vitro and in vivo correlation

6α-Methylprednisolone-loaded surfactant-free nanoparticles have been developed to palliate cisplatin ototoxicity. Nanoparticles were based on two different amphiphilic pseudo-block copolymers obtained by free radical polymerization and based on N-vinyl pyrrolidone and a methacrylic derivative of α-tocopheryl succinate or α-tocopherol. Copolymers formed spherical nanoparticles by nanoprecipitation in aqueous media that were able to encapsulate 6α-methylprednisolone in their inner core. The obtained nanovehicles were tested in vitro using HEI-OC1 cells and in vivo in a murine model. Unloaded nanoparticles were not able to significantly reduce the cisplatin ototoxicity. Loaded nanoparticles reduced cisplatin-ototoxicity in vitro being more active those based on the methacrylic derivative of vitamin E, due to their higher encapsulation efficiency. This formulation was able to protect hair cells in the base of the cochlea, having a positive effect in the highest frequencies tested in a murine model. A good correlation between the in vitro and the in vivo experiments was found.

FROM THE CLINICAL EDITOR

Cisplatin is a commonly used chemotherapeutic agent against many cancers clinically. However, one of the significant side-effects remains ototoxicity. Here, the authors presented their data on using 6α-methylprednisolone-loaded nanoparticles in the reduction of ototoxicity in in-vitro and in-vivo experiments. Early promising results should enable further refinement of adopting this new approach in future experiments.

Attenuation of Streptomycin Ototoxicity by Tetramethylpyrazine in Guinea Pig Cochlea

Objective

Tetramethylpyrazine has been suggested to have a therapeutic effect on impaired hearing that is induced by aminoglycoside antibiotics. However, its effectiveness on streptomycin ototoxicity and its cellular mechanisms are relatively unknown. Here we investigate the protective effect of tetramethylpyrazine on streptomycin-induced ototoxicity in guinea pig cochlea.

Study Design

Prospective randomized laboratory study.

Setting

Hearing Research Laboratory of China Medical University.

Subjects and Methods

Adult guinea pigs were randomized to 4 groups. Hearing sensitivity of guinea pigs was tested by auditory brainstem response measurements before streptomycin exposure and again 10 days later. The cochlear tissues were prepared for electron microscopy and immunohistochemical staining of heat shock protein 70 (HSP70). The effect of tetramethylpyrazine on streptomycin-induced activation of caspase-3 was evaluated by Western blotting.

Results

Co-therapy with tetramethylpyrazine reduced a profound streptomycin-induced auditory threshold shift compared with streptomycin treatment alone ( P = .0002 or P = .00008). Tetramethylpyrazine also attenuated the structural disruption in streptomycin-treated outer hair cells and marginal cells of vascular stria by transmission electronic microscopy and scanning electronic microscopy, respectively. Moreover, tetramethylpyrazine decreased the streptomycin-stimulated expressions of HSP70 and caspase-3. The correlation analysis demonstrated that HSP70 expression had a positive correlation with auditory brainstem response thresholds (|R| = 0.6-0.9, P = .0073 or P = .0169).

Conclusions

Our data suggest that the protective effect of tetramethylpyrazine on hearing function is associated with the reduction of stress response and inhibition of apoptosis. Tetramethylpyrazine may have therapeutic potential for patients with ototoxicity diseases.

Effect of neoadjuvant chemoradiation and postoperative radiotherapy on expression of heat shock protein 70 (HSP70) in head and neck vessels

Background

Preoperative radiotherapy and chemotherapy in patients with head and neck cancer result in changes to the vessels that are used to construct microsurgical anastomoses. The aim of the study was to investigate quantitative changes and HSP70 expression of irradiated neck recipient vessels and transplant vessels used for microsurgical anastomoses.

Methods

Of 20 patients included in this study five patients received neoadjuvant chemoradiation, another five received conventional radiotherapy and 10 patients where treated without previous radiotherapy. During surgical procedure, vessel specimens where obtained by the surgeon. Immunhistochemical staining of HSP70 was performed and quantitative measurement and evaluation of HSP70 was carried out.

Results

Conventional radiation and neoadjuvant chemoradiation revealed in a thickening of the intima layer of recipient vessels. A increased expression of HSP70 could be detected in the media layer of the recipient veins as well as in the transplant veins of patients treated with neoadjuvant chemoradiation. Radiation and chemoradiation decreased the HSP70 expression of the intima layer in recipient arteries. Conventional radiation led to a decrease of HSP70 expression in the media layer of recipient arteries.

Conclusion

Our results showed that anticancer drugs can lead to a thickening of the intima layer of transplant and recipient veins and also increase the HSP70 expression in the media layer of the recipient vessels. In contrast, conventional radiation decreased the HSP70 expression in the intima layer of arteries and the media layer of recipient arteries and veins. Comparing these results with wall thickness, it was concluded, that high levels of HSP70 may prevent the intima layer of arteries and the media layer of vein from thickening.