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Maeda A1, Iwashita Y2, Kuwabara T3, Wataru K2,4, Yamada S2, Nakamura T2,5, Iiyama J2, Mukoyama M3
1Kumamoto Health Science University Graduate School, Rehabilitation, Kumamoto, Japan, 2Kumamoto Health Science University, Rehabilitation, Kumamoto, Japan, 3Kumamoto University Graduate School of Medical Sciences, Nephrology, Kumamoto, Japan, 4Sakurajyuji Hospital, Rehabilitation, Kumamoto, Japan, 5Tamana Regional Health Medical Center, Rehabilitation, Tamana, Japan
Background: Cisplatin is used in various types of cancer for anticancer chemotherapy. However, cisplatin treatment has clinical side effects, including renal damage. We suggested in a previous study that mild systemic thermal stimulation (MTS) preconditioning, which raised rectal temperature by 1-2℃, reduced cisplatin-induced renal damage. Although it was related to the heat shock protein (HSP), detail mechanism with respect to thermal stimulation remains elusive. We noticed that the transient receptor vanilloid 4 (TRPV4) channel, which is activated by moderate warmth (>35℃), was highly expressed in the kidney.
Purpose: The purpose of this study to confirm the influence of TRPV4 on HSPs, oxidative stress, and inflammation by blocking TRPV4 during MTS preconditioning for cisplatin treatment.
Methods: Mice were divided into five groups, namely cisplatin non-injected under room temperature (Cont, n = 3), cisplatin-injected under room temperature (Cis, n = 3), cisplatin-injected with MTS (MTS+Cis, n = 3), cisplatin-injected with TRPV4 blocker under room temperature (Inh+Cis, n = 3), cisplatin-injected with TRPV4 blocker and MTS (Inh+MTS+Cis, n = 3). MTS pretreatment involved incubation at 39°C for 15 min, followed by 35°C for 20 min to maintain the elevation in body temperature by 1°C. Saline was injected at 3% of the body weight before MTS intervention to prevent dehydration. The TRPV4 blocker HC-067047 was injected intraperitoneally at 5 mg/kg before MTS. Cisplatin was injected intraperitoneally at 30 mg/kg at 3 hours after MTS. Samples were collected at 72 hours after cisplatin injection. Renal injury was evaluated by measuring blood urea nitrogen (BUN), plasma creatinine (CRE), and by histological examination using PAS staining. The expression of TRPV4, oxidative stress-related mRNA, and inflammation-related mRNA were detected by real-time PCR, and protein expressions were detected by western blotting.
Results: BUN level was significantly elevated by cisplatin injection (Cont: 31.2 ± 1.2 mg/dL, Cis: 100.7 ± 15.0 mg/dL; p 0.05). MTS pretreatment resulted in similar BUN levels as observed in Cont and similar levels were obtained using the TRPV4 blocker (MTS+Cis: 53.0 ± 13.6 mg/dL, Inh+Cis: 65.2 ± 30.9 mg/dL; NS vs. Cont). The CRE level also exhibited the same tendency as the levels of BUN. TRPV4 levels were markedly increased in the Cis group as compared with Cont (p 0.05); however, the levels were not increased in MTS or after TRPV4 blockage. The expression of small HSP-related genes were significantly increased in the Cis group (p 0.001, vs. Cont). However, the increase in HSP gene expression induced by cisplatin was significantly decreased by MTS pretreatment or TRPV4 blockage (p 0.05 vs. Cis). There was no difference in the NOX4 protein expression in all groups. However, eNOS protein expression was significantly decreased in the MTS pretreatment groups (p 0.01, vs. Cont). The expression of inflammation-related genes exhibited the same change as was observed for TRPV4 protein expression.
Conclusion(s): TRPV4 affected the MTS pretreatment-induced alleviation of cisplatin-induced renal damage.
Implications: These results suggest that TRPV4 expression plays an important role during MTS pretreatment for preventing cisplatin-induced renal damage.
Keywords: cisplatin-induced renal damage, systemic thermal stimulation, TRPV4
Funding acknowledgements: This work was supported in part by research grants from Japanese Ministry of Education, Culture, Sports, Science and Technology.
Purpose: The purpose of this study to confirm the influence of TRPV4 on HSPs, oxidative stress, and inflammation by blocking TRPV4 during MTS preconditioning for cisplatin treatment.
Methods: Mice were divided into five groups, namely cisplatin non-injected under room temperature (Cont, n = 3), cisplatin-injected under room temperature (Cis, n = 3), cisplatin-injected with MTS (MTS+Cis, n = 3), cisplatin-injected with TRPV4 blocker under room temperature (Inh+Cis, n = 3), cisplatin-injected with TRPV4 blocker and MTS (Inh+MTS+Cis, n = 3). MTS pretreatment involved incubation at 39°C for 15 min, followed by 35°C for 20 min to maintain the elevation in body temperature by 1°C. Saline was injected at 3% of the body weight before MTS intervention to prevent dehydration. The TRPV4 blocker HC-067047 was injected intraperitoneally at 5 mg/kg before MTS. Cisplatin was injected intraperitoneally at 30 mg/kg at 3 hours after MTS. Samples were collected at 72 hours after cisplatin injection. Renal injury was evaluated by measuring blood urea nitrogen (BUN), plasma creatinine (CRE), and by histological examination using PAS staining. The expression of TRPV4, oxidative stress-related mRNA, and inflammation-related mRNA were detected by real-time PCR, and protein expressions were detected by western blotting.
Results: BUN level was significantly elevated by cisplatin injection (Cont: 31.2 ± 1.2 mg/dL, Cis: 100.7 ± 15.0 mg/dL; p 0.05). MTS pretreatment resulted in similar BUN levels as observed in Cont and similar levels were obtained using the TRPV4 blocker (MTS+Cis: 53.0 ± 13.6 mg/dL, Inh+Cis: 65.2 ± 30.9 mg/dL; NS vs. Cont). The CRE level also exhibited the same tendency as the levels of BUN. TRPV4 levels were markedly increased in the Cis group as compared with Cont (p 0.05); however, the levels were not increased in MTS or after TRPV4 blockage. The expression of small HSP-related genes were significantly increased in the Cis group (p 0.001, vs. Cont). However, the increase in HSP gene expression induced by cisplatin was significantly decreased by MTS pretreatment or TRPV4 blockage (p 0.05 vs. Cis). There was no difference in the NOX4 protein expression in all groups. However, eNOS protein expression was significantly decreased in the MTS pretreatment groups (p 0.01, vs. Cont). The expression of inflammation-related genes exhibited the same change as was observed for TRPV4 protein expression.
Conclusion(s): TRPV4 affected the MTS pretreatment-induced alleviation of cisplatin-induced renal damage.
Implications: These results suggest that TRPV4 expression plays an important role during MTS pretreatment for preventing cisplatin-induced renal damage.
Keywords: cisplatin-induced renal damage, systemic thermal stimulation, TRPV4
Funding acknowledgements: This work was supported in part by research grants from Japanese Ministry of Education, Culture, Sports, Science and Technology.
Topic: Professional practice: other
Ethics approval required: Yes
Institution: Kumamoto Health Science University
Ethics committee: the Animal Care and Ethics Committee
Ethics number: 17-008
All authors, affiliations and abstracts have been published as submitted.
