Potential Protection Effect of ER Homeostasis of N6-(2-Hydroxyethyl)adenosine Isolated from Cordyceps cicadae in Nonsteroidal Anti-Inflammatory Drug-Stimulated Human Proximal Tubular Cells.

Charng-Cherng Chyau,Chiung-Chi Peng,Huei-Lin Wu,Cheng-Hsu Chen,Robert Y Peng,Shiau-Huei Huang,Chin-Chu Chen

doi:10.3390/ijms22041577

Abstract

Nonsteroidal anti-inflammatory drugs (NSAIDs) belong to a class of universally and commonly used anti-inflammatory analgesics worldwide. A diversity of drawbacks of NSAIDs have been reported including cellular oxidative stress, which in turn triggers the accumulation of unfolded proteins, enhancing endoplasmic reticulum stress, and finally resulting in renal cell damage. Cordyceps cicadae (CC) has been used as a traditional medicine for improving renal function via its anti-inflammatory effects. N6-(2-hydroxyethyl)adenosine (HEA), a physiologically active compound, has been reported from CC mycelia (CCM) with anti-inflammatory effects. We hypothesize that HEA could protect human proximal tubular cells (HK–2) from NSAID-mediated effects on differential gene expression at the mRNA and protein levels. To verify this, we first isolated HEA from CCM using Sephadex® LH–20 column chromatography. The MTT assay revealed HEA to be nontoxic up to 100 µM toward HK–2 cells. The HK–2 cells were pretreated with HEA (10–20 µM) and then insulted with the NSAIDs diclofenac (DCF, 200 µM) and meloxicam (MXC, 400 µM) for 24 h. HEA (20 µM) effectively prevented ER stress by attenuating ROS production (p < 0.001) and gene expression of ATF–6, PERK, IRE1α, CDCFHOP, IL1β, and NFκB within 24 h. Moreover, HEA reversed the increase of GRP78 and CHOP protein expression levels induced by DCF and MXC, and restored the ER homeostasis. These results demonstrated that HEA treatments effectively protect against DCF- and MXC-induced ER stress damage in human proximal tubular cells through regulation of the GRP78/ATF6/PERK/IRE1α/CHOP pathway.

Highlights

Nonsteroidal anti-inflammatory drugs (NSAIDs) have long been considered as safe medication practices in the treatment of inflammatory diseases, NSAIDs have received much special attention in the past few years due to the adverse effects in the inhibition of prostaglandin synthesis [1]
We propose that HEA could be beneficial to the prevention of renal damage via suppressing the C/EBP homologous protein (CHOP)-related endoplasmic reticulum (ER) stress, and this work is conducted to uncover such a mechanism of action, to point out the shortcomings of current NSAIDs therapy and comment the possible alternative treatments
We showed that HEA at doses of 20 μM effectively downregulated the expression of NFκB induced by DCF 8 h after treatment (Figure S1b): consistent with this, Lu et al reported that HEA attenuated proinflammatory responses via suppressing TLR4-mediated NF-κB signaling pathways [23]

Summary

Introduction

NSAIDs have long been considered as safe medication practices in the treatment of inflammatory diseases, NSAIDs have received much special attention in the past few years due to the adverse effects in the inhibition of prostaglandin synthesis [1]. NSAIDs reduce prostaglandin production by the inhibition of both COX–1 and COX–2, as a result, eliciting various electrolyte disturbances, acute renal failure and chronic renal effects [2,3,4,5,6]. The individual differences of adverse effects from these NSAIDs have been implicated in a variety of inhibitory effects in the cyclooxygenase (COX) regulatory inflammation reactions. DCF has been recognized as a nonselective NSAID inhibiting both COX–1 and COX–2, while MXC is known as a selective COX–2 inhibitor [2]. An increasing amount of evidence suggests that the risk of kidney injury associated with the use of NSAIDs is higher than that of the nonusers [3]

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Discussion

Conclusion