Treatment with catalpol protects against cisplatin-induced renal injury through Nrf2 and NF-κB signaling pathways

Loss of sphingosine kinase 2 protects against cisplatin-induced kidney injury

Cisplatin is an established chemotherapeutic drug for treatment of solid-organ cancers and is the primary drug used in the treatment of head and neck cancer; however, cisplatin-induced nephrotoxicity largely limits its clinical use. Inhibition of sphingosine kinase 2 (SphK2) has been demonstrated to alleviate various kidney diseases. Therefore, we hypothesized that inhibition of SphK2 could also protect against cisplatin-induced nephrotoxicity. Results from the present study showed that the SphK2 inhibitor ABC294640 or knockdown of SphK2 by siRNA blocked the cisplatin-induced increase of cellular injury markers (neutrophil gelatinase-associated lipocalin, kidney injury molecule-1, and cleaved caspase-3) by Western blot analysis in HK-2 cells, a human renal tubular cell line. In addition, SphK2 inhibition blocked cisplatin-induced activation of NF-κB by Western blot analysis and immunostaining analysis. Furthermore, SphK2 inhibition suppressed cisplatin-induced increases of proinflammatory markers (NLR family pyrin domain containing 3, interleukin-1β, and interleukin-6). Genetic deletion of the SphK2 gene in mice further confirmed that inhibition of SphK2 protected against cisplatin-induced kidney damage in vivo. Compared with wild-type mice, SphK2 knockout mice exhibited less renal dysfunction and reduced promotion of kidney injury markers, inflammatory factors, tubular morphology damage, and fibrotic staining. At the same time, the SphK2 inhibitor ABC294640 failed to interfere with the activity of cisplatin or radiation in two cell culture models of head and neck cancer. It is concluded that inhibition of Sphk2 protects against cisplatin-induced kidney injury. SphK2 may be used as a potential therapeutic target for the prevention or treatment of cisplatin-induced kidney injury.NEW & NOTEWORTHY The present study provides new findings that sphingosine kinase 2 (SphK2) is highly expressed in renal tubules, cisplatin treatment increases the expression of SphK2 in proximal tubular cells and kidneys, and inhibition of SphK2 alleviates cisplatin-induced kidney injury by suppressing the activation of NF-κB, production of inflammatory factors, and apoptosis. SphK2 may serve as a potential therapeutic target for the prevention or treatment of cisplatin-induced nephrotoxicity.

Catalpol Exerts Antidepressant-Like Effects by Enhancing Anti-oxidation and Neurotrophy and Inhibiting Neuroinflammation via Activation of HO-1

Catalpol is an iridoid glycoside with rich content, rich nutrition, and numerous biological activities in Rehmanniae Radix contained in classic antidepressant prescriptions in Chinese clinical medicine. Catalpol has been confirmed previously its exact antidepressant-like effect involved heme oxygenase (HO)-1, but its antidepressant molecular targets and mechanism are still unclear. Here, catalpol's antidepressant-like molecular target was diagnosed and confirmed by ZnPP intervention [the antagonist of HO-1, (10 μg/rat), intracerebroventricular] for the first time, and its molecule mechanism network was determined through HO-1 related pathway and molecules in the hippocampus. Results showed that ZnPP significantly abolished catalpol's (10 mg/kg) reversal on depressive-like behaviors of chronic unpredictable mild stress rats, abolished catalpol's up-regulation on the phosphorylation level of extracellular regulated protein kinases (ERK)1/2 and brain-derived neurotrophic factor (BDNF)'s receptor tropomyosin-related kinase B (TrkB), the nuclear expression level of nuclear factor E 2-related factor 2 (Nrf2), the levels of anti-oxidant factors (such as HO-1, SOD, GPX, GST, GSH) and BDNF, and abolished catalpol's down-regulation on the levels of peroxide and neuroinflammation factors [cyclooxygenase-2 (COX-2), induced nitrogen monoxide synthase (iNOS), nitric oxide (NO)]. Thus, HO-1 could serve as an important potential molecular target for catalpol's antidepressant-like process, and the antidepressant-like mechanism of catalpol could at least involve the activation of HO-1 triggering the up-regulation of the ERK1/2/Nrf2/HO-1 pathway-related factors to enhance the anti-oxidant defense, triggering the down-regulation of the COX-2/iNOS/NO pathway-related factors to inhibit neuroinflammation, and triggering the up-regulation of the BDNF/TrkB pathway to enhance neurotrophy.