Gingerol suppresses sepsis-induced acute kidney injury by modulating methylsulfonylmethane and dimethylamine production

Abstract

Acute kidney injury (AKI) and metabolic dysfunction are critical complications in sepsis syndrome; however, their pathophysiological mechanisms remain poorly understood. Therefore, we evaluated whether the pharmacological properties of 6-gingerol (6G) and 10-gingerol (10G) could modulate AKI and metabolic disruption in a rat model of sepsis (faecal peritonitis). Animals from the sham and AKI groups were intraperitoneally injected with 6G or 10G (25 mg/kg). Septic AKI decreased creatinine clearance and renal antioxidant activity, but enhanced oxidative stress and the renal mRNA levels of tumour necrosis factor-α, interleukin-1β, and transforming growth factor-β. Both phenol compounds repaired kidney function through antioxidant activity related to decreased oxidative/nitrosative stress and proinflammatory cytokines. Metabolomics analysis indicated different metabolic profiles for the sham surgery group, caecal ligation and puncture model alone group, and sepsis groups treated with gingerols. ¹H nuclear magnetic resonance analysis detected important increases in urinary creatine, allantoin, and dimethylglycine levels in septic rats. However, dimethylamine and methylsulfonylmethane metabolites were more frequently detected in septic animals treated with 6G or 10G, and were associated with increased survival of septic animals. Gingerols attenuated septic AKI by decreasing renal disturbances, oxidative stress, and inflammatory response through a mechanism possibly correlated with increased production of dimethylamine and methylsulfonylmethane.

Figure 1

Kidney redox profile. (a) Oxidative activities showed by the increased amounts of malondialdehide (MDA), (b) nitrite level, (c) but also by the reduced activity of glutathione (GSH) and (a) superoxide dismutase (SOD), indicating functional and cell disturbance in CLP model. On the other hand, gingerols showed antioxidant activity. The results are expressed as means ± SEM (n = 7–8). Statistical analysis was performed by ANOVA followed by Bonferroni’s multiple comparison test. **and *denote statistical significance compared to the sham group (P < 0.01, P < 0.05, respectively); ^#and ^##show significant difference compared to CLP group (P < 0.01, P < 0.05, respectively).

Figure 2

Gingerols suppress the mRNA expression of proinflammatory cytokines and renal biomarkers. CLP animals increased in kidney tissue the quantitative relative expression of (a) TNF-α, (b) IL-1β, (C) TGF-β1 and (d) KIM-1 mRNAs in the sepsis-induced AKI. Treatment with 6G and 10G decreased the pro-inflammatory cytokine of animals induced to septic AKI. Statistical analysis was performed by the Mann-Whitney test for RT-qPCR (n = 5–6). **and *denote statistical significance compared to the sham group (P < 0.05, P < 0.01, respectively); ^#show significant difference compared to CLP group (P < 0.05).

Figure 3

Gingerols increased survival in animals with septic AKI and decreased cell disorders. (a) LDH activity and (b) Lactate were used to verify the worsening of cellular functioning, denoting cellular disturbance in rats with septic AKI. Gingerol intervention ameliorated theses physiological responses. (c) Animals treated with both phenolic compounds, 6G and 10G 25 mg/Kg, preserve survival in septic AKI. The sham, sham-6G and sham-10G groups consisted of 8 animals and showed a 100% survival rate. The CLP group started with 15 animals, but only 8 animals survived. On the other hand, the CLP + 6G and CLP + 10G groups started with 11 animals, with the survival of 8 animals. The results are expressed as means ± SEM. Statistical analysis was performed by ANOVA followed by Bonferroni’s multiple comparison test. **and *denote statistical significance compared to the sham group (P < 0.01, P < 0.05, respectively); ^#and ^##show significant difference compared to CLP group (P < 0.01, P < 0.05, respectively).

Figure 4

Characterization of metabolomic profile on sepsis-induced AKI. (a) Representative ¹H NMR spectral profile of rat urines from animals belonging to the control group (sham), 6G group control (sham-6G), 10G group control (sham-10G), CLP-induced group (CLP), and gingerol-treated groups (CLP-6G and CLP-10G). (b,c) The PCA scores and the loadings from ¹H NMR spectra of urine samples revealed the natural grouping of samples and the metabolites responsible for the events.

Figure 5

The concentration of individual metabolites (expressed as mM/M of creatinine). The results are expressed as median (n = 7–8). Quantification of the major metabolites in the urine of the experimental groups: (a) acetate, (b) 2-oxoglutarate, (c) citrate, (d) taurine, (e) creatine, (f) allantoin, (g) dimethyglycine, (h) dimethylamine and (i) methylsulfonylmetane. Statistical analysis was performed by Kruskal-Wallis followed by Dunn’s test. **and * denote statistical significance compared to the sham group (P < 0.05, P < 0.01, respectively); ^#and ^##show significant difference compared to CLP group (P < 0.01, P < 0.05, respectively).

Figure 6

Summary of the key findings related to Gingerols activity on septic AKI and metabolic description. There are interesting protective effects of the phenol compounds with indication for intervention of renal injury. Both experimental procedures induced three different metabolomic profiles.