Caspase inhibitor z-VAD-FMK increases the survival of hair cells after Actinomycin-D-induced damage in vitro

GPR83 protects cochlear hair cells against ibrutinib-induced hearing loss through AKT signaling pathways

Introduction

Ibrutinib, widely used in leukemia treatment, has been implicated in sensorineural hearing loss; however, its underlying mechanisms remain unclear.

Methods

This study investigated the impact of ibrutinib on hearing using HEI-OC1 cells, cochlear explants and C57BL/6 J mice. We used RNA-sequences analysis to investigate the potential mechanisms of ibrutinib-induced ototoxicity. Mice received ibrutinib and auditory thresholds were assessed via auditory brainstem response testing; to assess the potential protective effects, we co-administered the caspase inhibitor Z-Val-Ala-Asp (OMe)-fluoromethylketone (Z-VAD-FMK) and monitored hearing.

Results

Z-VAD-FMK mitigated ibrutinib-induced hearing loss by inhibiting apoptosis in auditory cells. Ibrutinib exposure resulted in cochlear hair cell (HC) damage and subsequent hearing loss by inhibiting the protein kinase B and G protein-coupled receptor 83 (GPR83) pathways. RNA sequencing suggested that GPR83 protects HCs by modulating autophagy. Z-VAD-FMK application and GPR83 overexpression attenuated ibrutinib-induced cochlear HC apoptosis and auditory decline.

Conclusion

These findings confirm ibrutinib's ototoxicity and highlight the protective role of GPR83 in ibrutinib-induced hearing loss, supporting future clinical investigations into Z-VAD-FMK and GPR83 as interventions for ibrutinib or other chemotherapeutic drug-induced ototoxicity.

Pan-caspase inhibitor protects against noise-induced hearing loss in a rodent model

Background

Despite the high prevalence of noise-induced hearing loss (NIHL), no effective treatments exist currently. Underlying mechanisms behind NIHL include elevated reactive oxygen species and inflammation, all which ultimately lead to cellular apoptosis. Z-VAD-FMK, an apoptosis inhibitor, has demonstrated protective effects against cochlear hair cells exposed to ototoxic agents; however, its potential for treating NIHL remains unexplored. This study assessed the efficacy of Z-VAD-FMK as a therapeutic for noise-induced cochlear injury in a rodent model.

Methods

Rodents were assigned to one of four groups: (1) unexposed, (2) noise-exposed, (3) noise + vehicle, and (4) noise + Z-VAD-FMK. Noise delivery consisted of 1 h of 110 dB continuous white-noise, with Z-VAD-FMK administered intraperitoneally 6 h afterward. Auditory brainstem responses (ABRs), cochlear hair cell density, and protein levels were evaluated post-interventions.

Results

Noise exposure caused a permanent threshold shift across all frequencies, with minimal recovery by day 28. However, post-exposure treatment with Z-VAD-FMK significantly mitigated ABR threshold, amplitudes, and latencies shifts particularly at low and mid frequencies. Treatment rescued outer hair cells across middle and basal cochlear turns and reduced caspase-9 and IL-1β levels, as indicated by protein analysis.

Conclusion

Our findings indicate that a single intraperitoneal injection of Z-VAD-FMK can partially mitigate cochlear dysfunction induced by acoustic overexposure in a rodent model, highlighting its potential as a therapeutic intervention for NIHL.

Disulfiram ameliorates ischemia/reperfusion-induced acute kidney injury by suppressing the caspase-11-GSDMD pathway

Acute kidney injury (AKI) is a serious condition with high mortality. The most common cause is kidney ischemia/reperfusion (IR) injury, which is thought to be closely related to pyroptosis. Disulfiram is a well-known alcohol abuse drug, and recent studies have shown its ability to mitigate pyroptosis in mouse macrophages. This study investigated whether disulfiram could improve IR-induced AKI and elucidated the possible molecular mechanism. We generated an IR model in mouse kidneys and a hypoxia/reoxygenation (HR) injury model with murine tubular epithelial cells (MTECs). The results showed that IR caused renal dysfunction in mice and triggered pyroptosis in renal tubular epithelial cells, and disulfiram improved renal impairment after IR. The expression of proteins associated with the classical pyroptosis pathway (Nucleotide-binding oligomeric domain (NOD)-like receptor protein 3 (NLRP3), apoptosis-related specific protein (ASC), caspase-1, N-GSDMD) and nonclassical pyroptosis pathway (caspase-11, N-GSDMD) were upregulated after IR. Disulfiram blocked the upregulation of nonclassical but not all classical pyroptosis pathway proteins (NLRP3 and ASC), suggesting that disulfiram might reduce pyroptosis by inhibiting the caspase-11-GSDMD pathway. In vitro, HR increased intracellular ROS levels, the positive rate of PI staining and LDH levels in MTECs, all of which were reversed by disulfiram pretreatment. Furthermore, we performed a computer simulation of the TIR domain of TLR4 using homology modeling and identified a small molecular binding energy between disulfiram and the TIR domain. We concluded that disulfiram might inhibit pyroptosis by antagonizing TLR4 and inhibiting the caspase-11-GSDMD pathway.

Neuronal MD2 induces long-term mental impairments in septic mice by facilitating necroptosis and apoptosis

Sepsis-associated encephalopathy (SAE) is a complication of sepsis with high morbidity rates. Long-lasting mental health issues in patients with SAE result in a substantial decrease in quality of life. However, its underlying mechanism is unclear, and effective treatments are not available. In the current study, we explored the role of apoptosis and necroptosis related to mental dysfunction in sepsis. In a mouse model of sepsis constructed by cecal ligation and puncture (CLP), altered behavior was detected by the open field, elevated-plus maze and forced swimming tests on the fourteenth day. Moreover, apoptosis- and necroptosis-associated proteins and morphological changes were examined in the hippocampus of septic mice. Long-lasting depression-like behaviors were detected in the CLP mice, as well as significant increases in neuronal apoptosis and necroptosis. Importantly, we found that apoptosis and necroptosis were related according to Ramsay’s rule in the brains of the septic mice. Inhibiting myeloid differentiation factor 2 (MD2), the crosstalk mediator of apoptosis and necroptosis, in neurons effectively reduced neuronal loss and alleviated depression-like behaviors in the septic mice. These results suggest that neuronal death in the hippocampus contributes to the mental impairments in SAE and that inhibiting neuronal MD2 is a new strategy for treating mental health issues in sepsis by inhibiting necroptosis and apoptosis.