Protocatechuic acid-mediated DJ-1/PARK7 activation followed by PI3K/mTOR signaling pathway activation as a novel mechanism for protection against ketoprofen-induced oxidative damage in the gastrointestinal mucosa.

Oxidative stress contributes to the progression of non-steroidal anti-inflammatory drug (NSAID)-induced gastrointestinal (GI) cell apoptosis. In our previous study, we reported that nuclear factor erythroid 2-related factor 2 (Nrf2) plays a protective role against ketoprofen-induced GI mucosal oxidative injury. Recent reports suggest that Nrf2 could exhibit antioxidative and antiapoptosis responses through up-regulation of DJ-1 (PARK7). In the current study, we proposed that induction of DJ-1 expression by protocatechuic acid (PCA) might provide a potential therapeutic approach for treating oxidative stress-associated GI ulcer diseases. The results indicated that PCA increased mRNA expression of glutathione peroxidase and heme oxygenase-1 through up-regulation of DJ-1 followed by Nrf2 translocation. Furthermore, PCA protected Int-407 cells against ketoprofen-induced oxidative stress by regulating the DJ-1, PI3K, and mTOR pathways. Pretreatment with PCA inhibited mitochondrial ROS generation, up-regulated the mitochondrial membrane potential, and down-regulated pro-apoptotic Bax as well as downstream caspase-8, caspase-9, and caspase-3 activity, and reversed impaired DJ-1 and anti-apoptotic Bcl-2 protein expression in Int-407 cells induced by ketoprofen. Similar to the in vitro results, SD rats treated with PCA before administration of ketoprofen exhibited decreased caspase-3 protein expression as well as oxidative damage, and impairment of the antioxidant system and DJ-1 protein expression in the GI mucosa were reversed. The administration of lansoprazole, a type of proton pump inhibitor (PPI), strongly inhibited ketoprofen-induced GI mucosal injuries via up-regulation of DJ-1, indicating that DJ-1 is essential for the dietary antioxidant- and PPI drug-mediated mechanism of ulcer therapy. These results suggest that DJ-1 could be a novel target for protection against ketoprofen-induced GI ulcers due to its antioxidant and anti-apoptosis characteristics.

Beneficial Properties of Phytochemicals on NLRP3 Inflammasome-Mediated Gout and Complication.

Gouty arthritis is characterized by the precipitation of monosodium urate (MSU) crystals in the joint. Pro-inflammatory cytokine IL-1ß is a critical manifestation in response to MSU crystals attack. IL-1ß secretion is dependent on the nucleotide-binding oligomerization domain-like receptor pyrin domain containing 3 (NLRP3) inflammasome. Abnormal activation of the NLRP inflammasome is related to cellular oxidative stress. However, recent studies have illustrated that phytochemicals with potent antioxidant activity exert inhibitory effects on NLRP3 inflammasome-mediated diseases. This review focuses on the current findings of studies on the NLRP3 inflammasome and the proposed mechanisms that MSU crystals trigger inflammation via activation of the NLRP3 inflammasome. We also summarized the potential use of phytochemicals on NLRP3 inflammasome-mediated diseases, suggesting that phytochemicals can further prevent acute gout attack.

Epigallocatechin gallate inhibits urate crystals-induced peritoneal inflammation in C57BL/6 mice.

Gouty arthritis is a type of monosodium urate (MSU) crystals-induced inflammation in the articular tissue and shows the increased levels of neutrophil infiltration and IL-1ß secretion. MSU is capable of activating IL-1ß through a nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasome. Epigallocatechin gallate (EGCG), a bioactive polyphenol in green tea with potent antioxidant activity, is effective to prevent rheumatoid arthritis and osteoarthritis. However, it remains unclear whether EGCG improves gouty inflammation. This study aimed to investigate the effect of EGCG on MSU-induced inflammation and NLRP3 inflammasome activation. C57BL/6 mice were received subcutaneous injection or oral gavage of EGCG before the intraperitoneal injection of MSU. The results demonstrated that EGCG inhibited MSU-induced neutrophil infiltration and IL-1ß secretion. Furthermore, EGCG decreased MSU-triggered neutrophil cytosolic factor 1 and NLRP3 protein expression, limiting pro-inflammatory mediator secretion such as IL-1ß, IL-6, monocyte chemoattractant protein-1, and serum amyloid A. In addition, EGCG treatment suppressed NLRP3 inflammasome activation in MSU-challenged THP-1 monocytes. These findings indicate that EGCG treatment ameliorates MSU-induced inflammation, suggesting that EGCG exerts anti-inflammatory effect against MSU-induced acute gout attack.

Hypouricemic effects of Mesona procumbens Hemsl. through modulating xanthine oxidase activity in vitro and in vivo.

Uric acid is a metabolite obtained from purine by xanthine oxidase activity (XO) and high levels of serum uric acid leads to hyperuricemia and gout. Mesona procumbens Hemsl. has been used as a healthy beverage and a traditional remedy. In this study, the hypouricemic effects of M. procumbens extracts were evaluated in vitro and in vivo. The 50% ethanol extract of M. procumbens (EE50) showed the strongest inhibitory effect on monosodium urate (MSU)-induced XO activity in THP-1 cells. However, the phenolics and flavonoids in EE50 may not serve as inhibitors of XO. EE50 prevented an increase in the serum uric acid level in potassium oxonate (PO)-challenged ICR mice and streptozocin (STZ)-induced SD rats. EE50 down-regulated STZ-induced liver XO activity, and it restored renal OAT1 and urate transporter expression. STZ-induced renal interleukin-1ß (IL-1ß) and the tumor necrosis factor-α (TNF-α) level were inhibited by EE50 treatment. EE50 exhibits the hypouricemic effect via down-regulation of XO activity, suggesting that EE50 has potential to improve hyperuricemia and its complications.

Systematic revision of the Taiwanese genus Kurixalus members with a description of two new endemic species (Anura, Rhacophoridae).

Two new species of rhacophorid tree frog were identified in Taiwan. In both new taxa, derived reproductive characteristics of laying eggs in tree holes and oophagous tadpoles are shared with Kurixalus eiffingeri, but they are divergent from each other in molecular genetics, mating calls, and tadpole and adult morphology. The morphological characteristics and the molecular phylogenetic evidence support the hypothesis that the two new species, Kurixalus berylliniris sp. n. and Kurixalus wangi sp. n., are both monophyletic lineages.

Monosodium urate crystals trigger Nrf2- and heme oxygenase-1-dependent inflammation in THP-1 cells.

Gouty arthritis is an inflammatory disease that is caused by an accumulation of monosodium urate (MSU) crystals in the joints. MSU is capable of activating the nucleotide-binding oligomerization domain-like receptor pyrin domain containing 3 (NLRP3) inflammasome, leading to interleukin-1ß (IL-1ß) secretion. Reactive oxygen species (ROS) are major mediators of the NLRP3/IL-1ß interaction. Although nuclear factor E2-related factor 2 (Nrf2) is recognized as a transcription factor that is involved in the response to oxidative stress, the effect of MSU on Nrf2 and on Nrf2-mediated antioxidant enzymes remains unclear. The treatment of THP-1 monocytes using phorbol 12-myristate 13-acetate (PMA) was shown to initiate inflammatory responses. Here, we showed that THP-1 cells, following treatment with MSU crystals, significantly increased IL-1ß release, NLRP3 inflammasome activation and ROS production. MSU also promoted the nuclear translocation of Nrf2 and activated lysosomal destabilization. Moreover, the levels of heme oxygenase-1 (HO-1) in gene and protein expressions were upregulated by MSU. MSU-induced IL-1ß secretion and NLRP3 inflammasome activation were inhibited by the knockdown of Nrf2 and via the HO-1 inhibitor zinc (II) protoporphyrin IX (ZnPP). In addition, HO-1 inhibition increased the level of superoxide anion production and the consumption of glutathione. These findings suggest that Nrf2 and HO-1 mediate redox homeostasis and interact with pro-inflammatory factors in MSU-challenged THP-1 cells, thereby providing new insight into how MSU-induced gouty inflammation is mediated by specific mechanisms that are involved in the Nrf2/Ho-1 antioxidant signaling pathway.Cellular & Molecular Immunology advance online publication, 11 August 2014; doi:10.1038/cmi.2014.65.

Protective Effects of Catechin against Monosodium Urate-Induced Inflammation through the Modulation of NLRP3 Inflammasome Activation.

Gouty inflammation results from the stimulation of monosodium urate (MSU). Interleukin-1ß (IL-1ß) secretion is the primary clinical manifestation of MSU attack, and MSU activates IL-1ß through a nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasome. This study investigated the protective effect and underlying mechanism of naturally occurring phenolic compounds on MSU-induced inflammation in vivo and in vitro. A screening of phenolic compounds revealed that gallic acid and catechin exhibited the most potent free radical scavenging activities. Subcutaneous injection of gallic acid or catechin significantly reduced MSU-induced IL-1ß and IL-6 secretion in C57BL/6 mice. However, only catechin inhibited MSU-induced IL-1ß secretion and NLRP3 inflammasome activation in MSU-challenged THP-1 cells. MSU-triggered mitochondrial reactive oxygen species (MtROS) production and intracellular calcium levels were significantly decreased by treatment with catechin in THP-1 cells. Catechin treatment also up-regulated Bcl-2 levels and restored MSU-induced mitochondrial transmembrane potential impairment. These results indicate that the protective effects of catechin on MSU-induced IL-1ß secretion are associated with modulation of mitochondrial damage. It also suggests that catechin has the potential to protect gout attack by modulation of NLRP3 inflammasome activation.

DJ-1 plays an important role in caffeic acid-mediated protection of the gastrointestinal mucosa against ketoprofen-induced oxidative damage.

Ketoprofen is widely used to alleviate pain and inflammation in clinical medicine; however, this drug may cause oxidative stress and lead to gastrointestinal (GI) ulcers. We previously reported that nuclear factor erythroid 2-related factor 2 (Nrf2) plays a crucial role in protecting cells against reactive oxygen species, and it facilitates the prevention of ketoprofen-induced GI mucosal ulcers. Recent reports suggested that Nrf2 becomes unstable in the absence of DJ-1/PARK7, attenuating the activity of Nrf2-regulated downstream antioxidant enzymes. Thus, increasing Nrf2 translocation by DJ-1 may represent a novel means for GI protection. In vitro, caffeic acid increases the nuclear/cytosolic Nrf2 ratio and the mRNA expression of the downstream antioxidant enzymes, ϒ-glutamyl cysteine synthetase, glutathione peroxidase, glutathione reductase, and heme oxygenase-1, by activating the JNK/p38 pathway in Int-407 cells. Moreover, knockdown of DJ-1 also reversed caffeic acid-induced nuclear Nrf2 protein expression in a JNK/p38-dependent manner. Our results also indicated that treatment of Sprague-Dawley rats with caffeic acid prior to the administration of ketoprofen inhibited oxidative damage and reversed the inhibitory effects of ketoprofen on the antioxidant system and DJ-1 protein expression in the GI mucosa. Our observations suggest that DJ-1 plays an important role in caffeic acid-mediated protection against ketoprofen-induced oxidative damage in the GI mucosa.

Diallyl sulfide as a potential dietary agent to reduce TNF-α- and histamine-induced proinflammatory responses in A7r5 cells.

SCOPE: Oxidative stress-aggravated chronic inflammatory diseases of the airway are well documented; hence, treatment with antioxidants to ameliorate oxidative stress might be an effective strategy to reduce airway complications. The aim of this study was to investigate the effect and molecular mechanism of diallyl sulfide (DAS), which is a natural organosulfuric compound found in garlic, on the inhibition of tumor necrosis factor-alpha (TNF-α)- or histamine-induced inflammation in rat aortic smooth muscle A7r5 cells. METHODS AND RESULTS: A7r5 cells were coincubated with DAS before exposure to TNF-α or histamine. DAS significantly blocked the accumulation of the nuclear p65 protein in TNF-α-induced A7r5 cells by attenuating the TNF-α receptor complex through the dissociation of the TNF receptor-associated death domain and TNF receptor-associated factor 2. Moreover, DAS inhibited histamine-induced inflammation by decreasing reactive oxygen species (ROS) levels by enhancing the nuclear factor-erythroid 2-related factor 2-related antioxidative enzyme. DAS also inhibited inflammation by suppressing interleukin-1ß and TNF-α through the inhibition of ROS-induced PI3K/Akt and the downstream NF-κB and activator protein-1. CONCLUSION: Our results demonstrate that DAS is a potential phytochemical to inhibit TNF-α- and histamine-induced inflammation, suggesting that DAS might be an effective dietary agent for the prevention of oxidative stress-induced inflammation of the airway.