Resolution of Inflammation by Resolvin D1 Is Essential for Peroxisome Proliferator–activated Receptor-γ–mediated Analgesia during Postincisional Pain Development in Type 2 Diabetes

2015 ◽  
Vol 123 (6) ◽  
pp. 1420-1434 ◽  
Author(s):  
Takayuki Saito ◽  
Maiko Hasegawa-Moriyama ◽  
Tae Kurimoto ◽  
Tomotsugu Yamada ◽  
Eichi Inada ◽  
...  

Abstract Background The wound healing process following acute inflammation after surgery is impaired in diabetes. Altered macrophage functions are linked to delayed tissue repair and pain development in diabetes. Although peroxisome proliferator–activated receptor (PPAR)-γ agonists are used to treat diabetes, their postoperative analgesic effects in diabetes have not been evaluated. Methods The PPARγ agonist rosiglitazone (rosi) was injected at the incision site of diabetic (db/db) mice with resolvin (Rv) D1, a lipid mediator involved in resolution of inflammation. Pain-related behavior, neutrophil infiltration, phagocytosis, and macrophage polarity were assessed for 7 days postoperatively. Results Rosiglitazone and RvD1 alleviated mechanical hyperalgesia in db/db (db) mice, whereas rosiglitazone alone did not alter mechanical thresholds on days 4 (db rosi + RvD1 vs. db rosi: 0.506 ± 0.106 vs. 0.068 ± 0.12) and 7 (0.529 ± 0.184 vs. 0.153 ± 0.183) after incision (n = 10 per group). In control m/m mice, the rosiglitazone-induced analgesic effects were reversed by knockdown with arachidonate 5-lipoxygenase small interfering RNA, but these were restored by addition of RvD1. In db/db mice treated with rosiglitazone and RvD1, local infiltration of neutrophils was markedly reduced, with an associated decrease in total TdT-mediated dUTP nick-end labeling cells. Acceleration of rosiglitazone-induced phenotype conversion of infiltrated macrophages from M1 to M2 was impaired in db/db mice, but it was effectively restored by RvD1 in db/db wounds. Conclusions In diabetes, exogenous administration of RvD1 is essential for PPARγ-mediated analgesia during development of postincisional pain. Resolution of inflammation accelerated by RvD1 might promote PPARγ-mediated macrophage polarization to the M2 phenotype.

2003 ◽  
Vol 285 (1) ◽  
pp. G20-G30 ◽  
Author(s):  
Jianye Xu ◽  
Yumei Fu ◽  
Anping Chen

Hepatic fibrogenesis occurs as a wound-healing process after many forms of chronic liver injury. Hepatic fibrosis ultimately leads to cirrhosis if not treated effectively. During liver injury, quiescent hepatic stellate cells (HSC), the most relevant cell type, become active and proliferative. Oxidative stress is a major and critical factor for HSC activation. Activation of peroxisome proliferator-activated receptor-γ (PPAR-γ) inhibits the proliferation of nonadipocytes. The level of PPAR-γ is dramatically diminished along with activation of HSC. Curcumin, the yellow pigment in curry, is a potent antioxidant. The aims of this study were to evaluate the effect of curcumin on HSC proliferation and to begin elucidating underlying mechanisms. It was hypothesized that curcumin might inhibit the proliferation of activated HSC by inducing PPAR-γ gene expression and reviving PPAR-γ activation. Our results indicated that curcumin significantly inhibited the proliferation of activated HSC and induced apoptosis in vitro. We demonstrated, for the first time, that curcumin dramatically induced the gene expression of PPAR-γ and activated PPAR-γ in activated HSC. Blocking its trans-activating activity by a PPAR-γ antagonist markedly abrogated the effects of curcumin on inhibition of cell proliferation. Our results provide a novel insight into mechanisms underlying the inhibition of activated HSC growth by curcumin. The characteristics of curcumin, including antioxidant potential, reduction of activated HSC growth, and no adverse health effects, make it a potential antifibrotic candidate for prevention and treatment of hepatic fibrosis.


2020 ◽  
Vol 21 (15) ◽  
pp. 5296 ◽  
Author(s):  
Yutaro Tobita ◽  
Takeshi Arima ◽  
Yuji Nakano ◽  
Masaaki Uchiyama ◽  
Akira Shimizu ◽  
...  

The effects of peroxisome proliferator-activated receptor (PPAR)β/δ ophthalmic solution were investigated in a rat corneal alkali burn model. After alkali injury, GW501516 (PPARβ/δ agonist) or vehicle ophthalmic solution was topically instilled onto the rat’s cornea twice a day until day 7. Pathological findings were evaluated, and real-time reverse transcription polymerase chain reaction was performed. GW501516 strongly suppressed infiltration of neutrophils and pan-macrophages, and reduced the mRNA expression of interleukin-6, interleukin-1β, tumor necrosis factor alpha, and nuclear factor-kappa B. On the other hand, GW501516 promoted infiltration of M2 macrophages, infiltration of vascular endothelial cells associated with neovascularization in the wounded area, and expression of vascular endothelial growth factor A mRNA. However, 7-day administration of GW501516 did not promote neovascularization in uninjured normal corneas. Thus, the PPARβ/δ ligand suppressed inflammation and promoted neovascularization in the corneal wound healing process. These results will help to elucidate the role of PPARβ/δ in the field of ophthalmology.


2000 ◽  
Vol 279 (2) ◽  
pp. G304-G310 ◽  
Author(s):  
Hitoshi Ikeda ◽  
Yutaka Yatomi ◽  
Mikio Yanase ◽  
Hiroaki Satoh ◽  
Hisato Maekawa ◽  
...  

Sphingosine 1-phosphate (S-1-P), a lipid mediator shown to be a ligand for G protein-coupled receptors (AGRs), endothelial differentiation gene (EDG)1, EDG3, and AGR16/EDG5, is stored in platelets and released on their activation. Platelet consumption occurs in acute liver injury. Hepatic stellate cells (HSCs) play an important role in wound healing. Effects of S-1-P on HSCs were investigated. S-1-P enhanced proliferation of culture-activated HSCs. The mitogenic effect was pertussis toxin sensitive, mitogen-activated protein kinase dependent, and more prominent at lower cell density. S-1-P increased contraction of collagen lattices containing HSCs, irrespective of activation state, in a C3 exotoxin-sensitive manner. mRNAs of EDG1 and AGR16, but not of EDG3, were detected in HSCs. In HSC activation, EDG1 mRNA levels were downregulated, whereas AGR16 mRNA levels were unchanged. Considering that HSCs are capable of production of extracellular matrices and modulation of blood flow in sinusoids, our results suggest that S-1-P may play a role in wound healing process in the liver.


2012 ◽  
Vol 287 (42) ◽  
pp. 35161-35169 ◽  
Author(s):  
Jundong Zhou ◽  
Shuyu Zhang ◽  
Jing Xue ◽  
Jori Avery ◽  
Jinchang Wu ◽  
...  

Activation of peroxisome proliferator-activated receptor α (PPARα) has been demonstrated to inhibit tumor growth and angiogenesis, yet the mechanisms behind these actions remain to be characterized. In this study, we examined the effects of PPARα activation on the hypoxia-inducible factor-1α (HIF-1α) signaling pathway in human breast (MCF-7) and ovarian (A2780) cancer cells under hypoxia. Incubation of cancer cells under 1% oxygen for 16 h significantly induced HIF-1α expression and activity as assayed by Western blotting and reporter gene analysis. Treatment of the cells with PPARα agonists, but not a PPARγ agonist, prior to hypoxia diminished hypoxia-induced HIF-1α expression and activity, and addition of a PPARα antagonist attenuated the suppression of HIF-1α signaling. Activation of PPARα attenuated hypoxia-induced HA-tagged HIF-1α protein expression without affecting the HA-tagged HIF-1α mutant protein level, indicating that PPARα activation promotes HIF-1α degradation in these cells. This was further confirmed using proteasome inhibitors, which reversed PPARα-mediated suppression of HIF-1α expression under hypoxia. Using the co-immunoprecipitation technique, we found that activation of PPARα enhances the binding of HIF-1α to von Hippel-Lindau tumor suppressor (pVHL), a protein known to mediate HIF-1α degradation through the ubiquitin-proteasome pathway. Following PPARα-mediated suppression of HIF-1α signaling, VEGF secretion from the cancer cells was significantly reduced, and tube formation by endothelial cells was dramatically impaired. Taken together, these findings demonstrate for the first time that activation of PPARα suppresses hypoxia-induced HIF-1α signaling in cancer cells, providing novel insight into the anticancer properties of PPARα agonists.


2021 ◽  
Vol 22 (19) ◽  
pp. 10431
Author(s):  
Gábor Kökény ◽  
Laurent Calvier ◽  
Georg Hansmann

Peroxisome proliferator-activated receptor gamma (PPARγ) is a type II nuclear receptor, initially recognized in adipose tissue for its role in fatty acid storage and glucose metabolism. It promotes lipid uptake and adipogenesis by increasing insulin sensitivity and adiponectin release. Later, PPARγ was implicated in cardiac development and in critical conditions such as pulmonary arterial hypertension (PAH) and kidney failure. Recently, a cluster of different papers linked PPARγ signaling with another superfamily, the transforming growth factor beta (TGFβ), and its receptors, all of which play a major role in PAH and kidney failure. TGFβ is a multifunctional cytokine that drives inflammation, fibrosis, and cell differentiation while PPARγ activation reverses these adverse events in many models. Such opposite biological effects emphasize the delicate balance and complex crosstalk between PPARγ and TGFβ. Based on solid experimental and clinical evidence, the present review summarizes connections and their implications for PAH and kidney failure, highlighting the similarities and differences between lung and kidney mechanisms as well as discussing the therapeutic potential of PPARγ agonist pioglitazone.


2021 ◽  
Author(s):  
Fubiao Shi ◽  
Zoltan Simandi ◽  
Laszlo Nagy ◽  
Sheila Collins

AbstractIn addition to their established role to maintain blood pressure and fluid volume, the cardiac natriuretic peptides (NPs) can stimulate adipocyte lipolysis and control the brown fat gene program of nonshivering thermogenesis. The NP “clearance” receptor C (NPRC) functions to clear NPs from the circulation via peptide internalization and degradation and thus is an important regulator of NP signaling and adipocyte metabolism. It is well appreciated that the Nprc gene is highly expressed in adipose tissue and is dynamically regulated with nutrition and environmental changes. However, the molecular basis for how Nprc gene expression is regulated is still poorly understood. Here we identified Peroxisome Proliferator-Activated Receptor gamma (PPARγ) as a transcriptional regulator of Nprc expression in mouse adipocytes. During 3T3-L1 adipocyte differentiation, levels of Nprc expression increase in parallel with PPARγ induction. Rosiglitazone, a classic PPARγ agonist, increases, while siRNA knockdown of PPARγ reduces, Nprc expression in 3T3-L1 adipocytes. We demonstrate that PPARγ controls Nprc gene expression in adipocytes through its long-range distal enhancers. Furthermore, the induction of Nprc expression in adipose tissue during high-fat diet feeding is associated with increased PPARγ enhancer activity. Our findings define PPARγ as a mediator of adipocyte Nprc gene expression and establish a new connection between PPARγ and the control of adipocyte NP signaling in obesity.


Author(s):  
Hiromi Sato ◽  
Momoko Ishikawa ◽  
Hana Sugai ◽  
Asami Funaki ◽  
Yuki Kimura ◽  
...  

AbstractAdipose tissue plays important roles not only in storing fat but also in maintaining metabolic homeostasis by regulating hundreds of biological signaling events and the secretion of various cytokines. One of the central regulators of adipocyte differentiation is peroxisome proliferator-activated receptor γ (PPARγ), which promotes downstream transcriptional activities, such as adiponectin. Disruption of homeostasis leads to the onset of metabolic diseases such as type 2 diabetes and other triggers for metabolic syndrome. Males and post-menopausal females are more likely to be affected with metabolic diseases than pre-menopausal females, suggesting that sex hormones might be involved in the pathogenesis and development of metabolic diseases. Indeed, 17β-estradiol, testosterone, dihydrotestosterone, and their receptors clearly play a role in adipose regulation: they can alter fat distribution and can modify the expression and activities of PPARγ and its downstream adipocytokines. Furthermore, sex hormones affect inflammatory factors such as nitric oxygen, nitric oxygen synthase, and their surrounding components. Sex hormones are also suggested to be involved with sex differences in the efficacy of the PPARγ agonist thiazolidinediones. Therefore, thorough investigation of how sex hormone-dependent regulation of metabolic homeostasis occurs is necessary in order to develop individualized clinical therapies optimized with regard to each patient’s biological condition and drug sensitivities.


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