Regulation of COX-2 expression in human intestinal myofibroblasts: mechanisms of IL-1-mediated induction

Electroacupuncture regulates microglial polarization via inhibiting NF-κB/COX2 pathway following traumatic brain injury

BACKGROUND

Neuroinflammation and oxidative stress are important pathological mechanisms following traumatic brain injury (TBI). The NF-κB/COX2 pathway regulates neuroinflammation and oxidative damage, while microglia also play an important role in neuroinflammation. Since NF-κB is involved in microglial polarization, targeting this pathway and microglial polarization is a critical component of TBI treatment. Currently, electroacupuncture (EA) is widely used to treat various symptoms after TBI, but the mechanisms of EA remain poorly understood. Additionally, the optimal frequency of EA remains unclear, which affects its efficacy. This study focuses on exploring the optimal frequency parameters of EA on TBI and investigating the underlying mechanisms of EA through NF-κB/COX2 pathway and microglial polarization.

METHODS

The study was divided into two parts. In Experiment 1, 42 Sprague Dawley (SD) rats were induced and randomly divided into seven groups (n = 6). Except for the sham group, all rats underwent controlled cortical impact (CCI) to establish TBI model. Four EA groups (with different frequencies) and manual acupuncture (without current stimulation) received stimulation on the acupoints of Shuigou (GV26), Fengchi (GB20) and Neiguan (PC6) once a day for 7 days. The neurological function was assessed by modified Neurological Severity Scores (mNSS), and the rats' memory and learning were examined by the Morris water maze (MWM). SOD, MDA, and GSH-Px were detected to evaluate the levels of oxidative stress. The levels of IL-1β, IL-6, and TNF-α were evaluated by Enzyme Linked Immunosorbent Assay (ELISA). Detection of the above indicators indicated a treatment group that exerted the strongest neuroprotection against TBI, we then conducted Experiment 2 using this screened acupuncture treatment to investigate the mechanism of acupuncture. 48 rats were randomly divided into four groups (n = 12): sham, TBI model, acupuncture and PDTC (NF-κB inhibitor). Evaluations of mNSS, MWM test, SOD, MDA, GSH-Px, IL-1β, IL-6, TNF-α, and IL-10 were the same as in Experiment 1. Western blot was applied for detecting the expression levels of NF-κB, p-NF-κB, COX2, and Arg-1. TUNEL was used to examine neuronal apoptosis. Brain structure was observed by H&E. Iba-1, COX2, and Arg-1 were investigated by immunofluorescence staining.

RESULTS

EA with frequency of 2/100 Hz markedly improved neuronal and cognitive function as compared to the other treatment groups. Moreover, it downregulated the expression of MDA, IL-6, IL-1β, and TNF-α and upregulated the levels of SOD and GSH-Px. In addition, Both EA with 2/100 Hz and PDTC reduced the levels of p-NF-κB, COX2 and M1 markers (COX2, IL-6, IL-1β, TNF-α) and increased the levels of M2 markers (Arg-1, IL-10). Moreover, they had similar effects on reducing inflammation, oxidative stress and apoptosis, and improving neuronal and cognitive function.

CONCLUSIONS

The collective findings strongly suggest that EA with 2/100 Hz can improve neurologic function by suppressing neuroinflammation, oxidative stress and apoptosis. Additionally, we confirm that EA promotes microglial polarization towards the M2 phenotype through the suppression of NF-κB/COX2 pathway, thus exerting neuroprotective effects after TBI.

Loss of alcohol dehydrogenase 1B in cancer-associated fibroblasts: contribution to the increase of tumor-promoting IL-6 in colon cancer

BACKGROUND

Increases in IL-6 by cancer-associated fibroblasts (CAFs) contribute to colon cancer progression, but the mechanisms involved in the increase of this tumor-promoting cytokine are unknown. The aim of this study was to identify novel targets involved in the dysregulation of IL-6 expression by CAFs in colon cancer.

METHODS

Colonic normal (N), hyperplastic, tubular adenoma, adenocarcinoma tissues, and tissue-derived myo-/fibroblasts (MFs) were used in these studies.

RESULTS

Transcriptomic analysis demonstrated a striking decrease in alcohol dehydrogenase 1B (ADH1B) expression, a gene potentially involved in IL-6 dysregulation in CAFs. ADH1B expression was downregulated in approximately 50% of studied tubular adenomas and all T1-4 colon tumors, but not in hyperplastic polyps. ADH1B metabolizes alcohols, including retinol (RO), and is involved in the generation of all-trans retinoic acid (atRA). LPS-induced IL-6 production was inhibited by either RO or its byproduct atRA in N-MFs, but only atRA was effective in CAFs. Silencing ADH1B in N-MFs significantly upregulated LPS-induced IL-6 similar to those observed in CAFs and lead to the loss of RO inhibitory effect on inducible IL-6 expression.

CONCLUSION

Our data identify ADH1B as a novel potential mesenchymal tumor suppressor, which plays a critical role in ADH1B/retinoid-mediated regulation of tumor-promoting IL-6.

Leishmania infection-derived extracellular vesicles drive transcription of genes involved in M2 polarization

Although it is known that the composition of extracellular vesicles (EVs) is determined by the characteristics of the cell and its environment, the effects of intracellular infection on EV composition and functions are not well understood. We had previously shown that cultured macrophages infected with Leishmania parasites release EVs (LiEVs) containing parasite-derived molecules. In this study we show that LdVash, a molecule previously identified in LiEVs from L. donovani infected RAW264.7 macrophages, is widely distributed in the liver of L. donovani infected mice. This result shows for the first time that parasite molecules are released in EVs and distributed in infected tissues where they can be endocytosed by cells in the liver, including macrophages that significantly increase numbers as the infection progresses. To evaluate the potential impact of LiEVs on macrophage functions, we show that primary peritoneal exudate macrophages (PECs) express transcripts of signature molecules of M2 macrophages such as arginase 1, IL-10, and IL-4R when incubated with LiEVs. In comparative studies that illustrate how intracellular pathogens control the composition and functions of EVs released from macrophages, we show that EVs from RAW264.7 macrophages infected with Salmonella Typhimurium activate PECs to express transcripts of signature molecules of M1 macrophages such as iNOS, TNF alpha, and IFN-gamma and not M2 signature molecules. Finally, in contrast to the polarized responses observed in in vitro studies of macrophages, both M1 and M2 signature molecules are detected in L. donovani infected livers, although they exhibit differences in their spatial distribution in infected tissues. In conclusion, EVs produced by macrophages during Leishmania infection lead to the gene expression consistent with M2 polarization. In contrast, the EVs produced during S. Typhimurium infection stimulated the transcription of genes associated with M1 polarization.

Colon Fibroblasts and Inflammation: Sparring Partners in Colorectal Cancer Initiation?

Simple Summary

Colorectal cancer (CRC) is the third most common cause of cancer-related death. Patients suffering inflammatory bowel disease have an increased risk of CRC. It is admitted that CRC found its origin within crypts of the colon mucosa, which host the intestinal stem cells (ISCs) responsible of the tissue renewal. ISC behavior is controlled by the fibroblasts that surround the crypt. During inflammation, the signals delivered by fibroblasts are altered, leading to stem cells’ dysregulation, possibly turning them into cancer-initiating cells. Here, we reviewed the interplays between the fibroblast and the ISCs, possibly leading to the initiation of CRC due to chronic inflammation.

Abstract

Colorectal cancer (CRC) is the third most common cause of cancer-related death. Significant improvements in CRC treatment have been made for the last 20 years, on one hand thanks to a better detection, allowing surgical resection of the incriminated area, and on the other hand, thanks to a better knowledge of CRC’s development allowing the improvement of drug strategies. Despite this crucial progress, CRC remains a public health issue. The current model for CRC initiation and progression is based on accumulation of sequential known genetic mutations in the colon epithelial cells’ genome leading to a loss of control over proliferation and survival. However, increasing evidence reveals that CRC initiation is more complex. Indeed, chronic inflammatory contexts, such as inflammatory bowel diseases, have been shown to increase the risk for CRC development in mice and humans. In this manuscript, we review whether colon fibroblasts can go from the main regulators of the ISC homeostasis, regulating not only the renewal process but also the epithelial cells’ differentiation occurring along the colon crypt, to the main player in the initiation of the colorectal cancer process due to chronic inflammation.

Lats1 and Lats2 are required for the maintenance of multipotency in the Müllerian duct mesenchyme

WNT signaling plays essential roles in the development and function of the female reproductive tract. Although crosstalk with the Hippo pathway is a key regulator of WNT signaling, whether Hippo itself plays a role in female reproductive biology remains largely unknown. Here, we show that conditional deletion of the key Hippo kinases Lats1 and Lats2 in mouse Müllerian duct mesenchyme cells caused them to adopt the myofibroblast cell fate, resulting in profound reproductive tract developmental defects and sterility. Myofibroblast differentiation was attributed to increased YAP and TAZ expression (but not to altered WNT signaling), leading to the direct transcriptional upregulation of Ctgf and the activation of the myofibroblast genetic program. Müllerian duct mesenchyme cells also became myofibroblasts in male mutant embryos, which impeded the development of the male reproductive tract and resulted in cryptorchidism. The inactivation of Lats1/2 in differentiated uterine stromal cells in vitro did not compromise their ability to decidualize, suggesting that Hippo is dispensable during implantation. We conclude that Hippo signaling is required to suppress the myofibroblast genetic program and maintain multipotency in Müllerian mesenchyme cells.

The Possible Role of Helicobacter pylori in Gastric Cancer and Its Management

Helicobacter pylori (HP) is a facultative anaerobic bacterium. HP is a normal flora having immuno-modulating properties. This bacterium is an example of a microorganism inducing gastric cancer. Its carcinogenicity depends on bacteria-host related factors. The proper understanding of the biology of HP inducing gastric cancer offers the potential strategy in the managing of HP rather than eradicating it. In this article, we try to summarize the biology of HP-induced gastric cancer and discuss the current pharmacological approach to treat and prevent its carcinogenicity.

Fluorine-Modified Rutaecarpine Exerts Cyclooxygenase-2 Inhibition and Anti-inflammatory Effects in Lungs

Inflammation is the first step that leads to inflammatory cell migration, cytokine release, and myofibroblast formation. Myofibroblasts can deposit excess amounts of extracellular matrix. Cyclooxygenase (COX) inhibitor exhibits strong anti-inflammatory response; however, this is usually achieved with undesirable side effects. In this study, we demonstrated the effects of the fluorine-modified rutaecarpine (RUT), fluoro-2-methoxyrutaecarpine (F-RUT), in inflammatory damage in the lungs. Based on the results, F-RUT retained anti-inflammatory activity both in vitro and in vivo in lungs. Compared to the parent compound, F-RUT showed better COX-2 suppression as a COX-2-selective inhibitor with lower cytotoxicity, and enhanced molecular reactivity and biological activity. F-RUT was also observed to reduce reactive oxygen species (ROS) generation and inflammatory infiltrating neutrophils in lipopolysaccharide (LPS)-stimulated zebrafish and ovalbumin (OVA)/alum-challenged KLF-10-knockout mouse lungs, respectively. Furthermore, F-RUT ameliorated the respiratory function in OVA/alum-challenged BALB/c mice by maintaining the thickness of the blood-air barrier in mouse lungs. Overall, these data suggest that F-RUT may function as an effective therapeutic agent for inflammation-induced lung dysfunction, and a better selection for pharmaceutical purposes than conventionally used anti-inflammatory agents.

PGE2 Augments Inflammasome Activation and M1 Polarization in Macrophages Infected With Salmonella Typhimurium and Yersinia enterocolitica

Eicosanoids are cellular metabolites, which shape the immune response, including inflammatory processes in macrophages. The effects of these lipid mediators on inflammation and bacterial pathogenesis are not clearly understood. Certain eicosanoids are suspected to act as molecular sensors for the recruitment of neutrophils, while others regulate bacterial uptake. In this study, gene expression analyses indicated that genes involved in eicosanoid biosynthesis including COX-1, COX-2, DAGL, and PLA-2 are differentially regulated in THP-1 human macrophages infected with Salmonella enterica Typhimurium or Yersinia enterocolitica. By using targeted metabolomics approach, we found that the eicosanoid precursor, arachidonic acid (AA) as well as its derivatives, including prostaglandins (PGs) PGF2α or PGE2/PGD2, and thromboxane TxB2, are rapidly secreted from macrophages infected with these Gram-negative pathogenic bacteria. The magnitude of eicosanoid biosynthesis in infected host cells depends on the presence of virulence factors of Y. enterocolitica and S. Typhimurium strains, albeit in an opposite way in Y. enterocolitica compared to S. Typhimurium infection. Trials with combinations of EP2/EP4 PGE2 receptor agonists and antagonists suggest that PGE2 signaling in these infection models works primarily through the EP4 receptor. Downstream of EP4 activation, PGE2 enhances inflammasome activation and represses M2 macrophage polarization while inducing key M1-type markers. PGE2 also led to a decreased numbers of Y. enterocolitica within macrophages. To summarize, PGE2 is a potent autocrine/paracrine activator of inflammation during infection in Gram-negative bacteria, and it affects macrophage polarization, likely controlling bacterial clearance by macrophages.

Lactobacillus rhamnosus GG increases cyclooxygenase-2 expression and prostaglandin E2 secretion in colonic myofibroblasts via a MyD88-dependent mechanism during homeostasis

Prostaglandin E2 (PGE₂ ) plays a critical role in intestinal mucosal tolerance and barrier integrity. Cyclooxygenase-2 (COX-2)-dependent PGE₂ production involves mobilisation of arachidonic acid. Lactobacillus rhamnosus GG (LbGG) is one of the most widely used probiotics reported to colonise the colonic mucosa. LbGG contributes to the protection of the small intestine against radiation injury through the repositioning of mucosal COX-2 expressing cells. However, it is unknown if LbGG modulates PGE₂ production in the colonic mucosa under homeostasis and the major cellular elements involved in these processes. Colonic epithelial and CD90⁺ mesenchymal stromal cells, also known as (myo) fibroblasts (CMFs), are abundant innate immune cells in normal colonic mucosa able to produce PGE₂ . Herein, we tested the hypothesis that under colonic mucosal homeostasis, LbGG modulates the eicosanoid pathway resulting in increased PGE₂ production in both epithelial and stromal cells. Among the five tested human colonic epithelial cell lines, only exposure of Caco-2 to LbGG for 24 hr led to the mobilisation of arachidonic acid with concomitant increase in the components within the leukotriene and COX-2-dependent PGE₂ pathways. By contrast, CMFs isolated from the normal human colonic mucosa responded to LbGG with increased expression of COX-2 and PGE₂ in the prostaglandin pathway, but not 5-LO in the leukotriene pathway. Oral gavage of C57BL/6 mice for 5 days with LbGG (5 × 10⁸ Colony-Forming Unit (CFU)/dose) increased COX-2 expression in the colonic mucosa. The majority of cells upregulating COX-2 protein expression were located in the colonic lamina propria and colocalised with α-SMA⁺ cells corresponding to the CMF phenotype. This process was myeloid differentiation factor-88-dependent, because silencing of myeloid differentiation factor-88 expression in CMFs abrogated LbGG-induced upregulation of COX-2 in culture and in vivo. Taken together, our data suggest that LbGG increases release of COX-2-mediated PGE₂ , contributing to the maintenance of mucosal homeostasis in the colon and CMFs are among the major contributors to this process.

Signaling Pathways Regulating IL-1α-induced COX-2 Expression

Interleukin-1α(IL-1α) stimulates the production of prostaglandin E2 (PGE2) in odontogenic keratocyst fibroblasts. However, the signaling pathways remain obscure. In this study, we investigated IL-1αsignaling pathways that regulate cyclooxygenase-2 (COX-2) expression in odontogenic keratocyst fibroblasts. IL-1αincreased the expression of COX-2 mRNA and protein, and PGE2 secretion in the fibroblasts. IL-1αincreased the phosphorylation of extracellular signal-regulated protein kinase-1/2 (ERK1/2), p38 mitogen-activated protein kinase (MAPK), and c-Jun N-terminal kinase (JNK). PD-98059, SB-203580, SP-600125, and PDTC—which are inhibitors of ERK1/2, p38, JNK, and nuclear factor-κB (NF-κB), respectively—attenuated the IL-1α-induced COX-2 mRNA expression and activated protein kinase C PGE2 secretion. IL-1α(PKC), and PKC inhibitor staurosporine inhibited IL-1α-induced phosphorylation of ERK1/2, p38, and JNK, and decreased IL-1α-induced COX-2 mRNA expression. Thus, in odontogenic keratocyst fibroblasts, IL-1αmay stimulate COX-2 expression both through the PKC-dependent activation of ERK1/2, p38, and JNK signaling pathways, and through the NF-κB cascade.

Effects of Dietary Selenium on Inflammation and Hydrogen Sulfide in the Gastrointestinal Tract in Chickens

Selenium (Se) is an essential trace element for humans and animals and is associated with many physiological functions. Previous studies have shown that low-Se diet may affect inflammatory cytokine productions and histology in the digestive system and that sulfide hydrogen (H₂S) may contribute to the protection against tissue injury and the inhibition of inflammation in the gastrointestinal tract. In this study, we investigated the relationship between Se deficiency-induced inflammation and H₂S production in the small intestine in chickens. One hundred twenty 1-day-old chickens were fed with diets with different Se concentrations (0.15 mg/kg in the control and 0.028 mg/kg in the low-Se-diet group). Chickens were euthanized and small intestinal tissues were extracted. We observed histology, measured H₂S concentration, and evaluated the mRNA expression of H₂S-producing enzymes cystathionine γ-lyase (CSE), cystathionine β-synthase (CBS), and 3-mercaptopyruvate sulfurtransferase (3-MST), and inflammatory factors TNF-α, NF-κB p50, COX-2, and PTGES. Our results showed that chickens fed with low-Se diet exhibited histological changes, lower H₂S production, and lower mRNA expression of H₂S-producing enzymes (CSE, CBS, and 3-MST) whereas higher mRNA expression of intestinal inflammatory factors (TNF-α, NF-κB p50, COX-2, and PTGES) compared to controls. Our results indicate that low-Se diet could impact H₂S, H₂S-producing enzymes, and inflammatory factors in the small intestine, implying that Se is important in maintaining intestinal functions and H₂S production is downregulated in Se deficiency-induced inflammation. The downregulation exacerbates the inflammation and impacts H₂S-mediated intestinal functions.

Selenium Deficiency-Induced Inflammation and Increased Expression of Regulating Inflammatory Cytokines in the Chicken Gastrointestinal Tract

Selenium (Se), a nutritionally essential trace element, plays an important role in various aspects of health for a wide range of species, including birds. Se deficiency inhibits the growth of immune organs and decreases immune function, leading to many inflammatory diseases. The present study determined the effects and mechanism of dietary Se deficiency on gastrointestinal tract tissue inflammation. The histopathological changes showed that Se deficiency induced inflammatory lesions in the gastrointestinal tract tissues (glandular stomach, gizzard, duodenum, small intestine, and rectum). The expression levels of PTGE (prostagland E synthase), COX-2 (cyclooxygenase-2), TNF-α (tumor necrosis factor α), and NF-κB (nuclear transfer factor κB) in the gastrointestinal tract tissues (glandular stomach, gizzard, duodenum, small intestine, and rectum) were determined by qPCR on days 15, 25, 35, 45, and 55, respectively. The results showed that Se deficiency induced high expression levels of PTGE, COX-2, TNF-α, and NF-κB in the gastrointestinal tract tissues. The effects were more obvious in the duodenum and small intestine than those in the glandular stomach, gizzard, and rectum. In addition, the expression levels of these proteins in the gastrointestinal tract tissue increased in a time-dependent manner with Se deficiency feeding time. Furthermore, Se deficiency induced the production of pro-inflammatory factors, thus aggravating inflammatory lesions in the gastrointestinal tract. The effect of Se deficiency on inflammation and other gastrointestinal tract diseases should be further studied.

Fibroblasts and myofibroblasts of the intestinal lamina propria in physiology and disease

In this Review we summarize our current understanding of the biology of mesenchymal cells of the intestinal lamina propria focusing mainly on fibroblasts and myofibroblasts. The topics covered include 1) the embryonic origin of mesenchymal cells of the intestinal lamina propria and their heterogeneity in adults, 2) the role of the mesenchyme in intestinal development, 3) the physiological function of fibroblasts and myofibroblasts in adults as part of the intestinal stem cell niche and the mucosal immune system and 4) the involvement of fibroblasts and myofibroblasts in epithelial homeostasis upon injury and in the pathogenesis of diseases such as Inflammatory Bowel Diseases, fibrosis and cancer. We emphasize studies addressing the function of intestinal mesenchymal cells in vivo, and also discuss major open questions and current challenges in this field.

Gprc5a-deficiency confers susceptibility to endotoxin-induced acute lung injury via NF-κB pathway

Susceptibility to acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) varies greatly among patients in sepsis/septic shock. The genetic and biochemical reasons for the difference are not fully understood. G protein coupled receptor family C group 5 member A (GPRC5A), a retinoic acid target gene, is predominately expressed in the bronchioalveolar epithelium of lung. We hypothesized that Gprc5a is important in controlling the susceptibility to ALI or ARDS. In this study, we examined the susceptibility of wild-type and Gprc5a-knockout (ko) mice to induced ALI. Administration of endotoxin LPS induced an increased pulmonary edema and injury in Gprc5a-ko mice, compared to wild-type counterparts. Consistently, LPS administration induced higher levels of inflammatory cytokines (IL-1β and TNFα) and chemokine (KC) in Gprc5a-ko mouse lungs than in wild-type. The enhanced pulmonary inflammatory responses were associated with dysregulated NF-κB signaling in the bronchioalveolar epithelium of Gprc5a-ko mouse lungs. Importantly, selective inhibition of NF-κB through expression of the super-repressor IκBα in the bronchioalveolar epithelium of Gprc5a-ko mouse lungs alleviated the LPS-induced pulmonary injury, and inflammatory response. Thus, Gprc5a is critical for lung homeostasis, and Gprc5a deficiency confers the susceptibility to endotoxin-induced pulmonary edema and injury, mainly through NF-κB signaling in bronchioalveolar epithelium of lung.

Reactive oxygen species induce Cox-2 expression via TAK1 activation in synovial fibroblast cells

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Oxidative stress in the arthritis joint is involved in generating mediators for inflammation.

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Oxidative stress-induced expression of Cox-2 was mediated by MAPKs and NF-κB.

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ROS-induced MAPKs and NF-κB were attenuated by inhibition of MAPKKK TAK1.

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Inhibition of TAK1 activity resulted in reduced expression of Cox-2 and PGE2.

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ROS-induced TAK1 activation and Cox-2 expression was inhibited by antioxidants N-acetyl cysteamine and hyaluronic acid.

Oxidative stress within the arthritis joint has been indicated to be involved in generating mediators for tissue degeneration and inflammation. COX-2 is a mediator in inflammatory action, pain and some catabolic reactions in inflamed tissues. Here, we demonstrated a direct relationship between oxidative stress and Cox-2 expression in the bovine synovial fibroblasts. Furthermore, we elucidated a novel mechanism, in which oxidative stress induced phosphorylation of MAPKs and NF-κB through TAK1 activation and resulted in increased Cox-2 and prostaglandin E2 expression. Finally, we demonstrated that ROS-induced Cox-2 expression was inhibited by supplementation of an antioxidant such as N-acetyl cysteamine and hyaluronic acid in vitro and in vivo. From these results, we conclude that oxidative stress is an important factor for generation of Cox-2 in synovial fibroblasts and thus its neutralization may be an effective strategy in palliative therapy for chronic joint diseases.

Cyclooxygenase-2 regulates NLRP3 inflammasome-derived IL-1β production

The NLR family, pyrin domain-containing 3 (NLRP3) inflammasome is a reactive oxygen species-sensitive multiprotein complex that regulates IL-1β maturation via caspase-1. It also plays an important role in the pathogenesis of inflammation-related disease. Cyclooxygenase-2 (COX-2) is induced by inflammatory stimuli and contributes to the pathogenesis of inflammation-related diseases. However, there is currently little known about the relationship between COX-2 and the NLRP3 inflammasome. Here, we describe a novel role for COX-2 in regulating the activation of the NLRP3 inflammasome. NLRP3 inflammasome-derived IL-1β secretion and pyroptosis in macrophages were reduced by pharmaceutical inhibition or genetic knockdown of COX-2. COX-2 catalyzes the synthesis of prostaglandin E2 and increases IL-1β secretion. Conversely, pharmaceutical inhibition or genetic knockdown of prostaglandin E2 receptor 3 reduced IL-1β secretion. The underlying mechanisms for the COX-2-mediated increase in NLRP3 inflammasome activation were determined to be the following: (1) enhancement of lipopolysaccharide-induced proIL-1β and NLRP3 expression by increasing NF-κB activation and (2) enhancement of the caspase-1 activation by increasing damaged mitochondria, mitochondrial reactive oxygen species production and release of mitochondrial DNA into cytosol. Furthermore, inhibition of COX-2 in mice in vivo with celecoxib reduced serum levels of IL-1β and caspase-1 activity in the spleen and liver in response to lipopolysaccharide (LPS) challenge. These findings provide new insights into how COX-2 regulates the activation of the NLRP3 inflammasome and suggest that it may be a new potential therapeutic target in NLRP3 inflammasome-related diseases.

Serum surfactant protein D (SP-D) is a prognostic marker of poor outcome in patients with A/H1N1 virus infection

Introduction

Surfactant protein D (SP-D) plays an important role in the innate responses against pathogens and its production is altered in lung disorders.

Methods

We studied the circulating levels of SP-D in 37 patients with acute respiratory distress syndrome due to the A/H1N1 virus infection and in 40 healthy controls. Cox logistic regression models were constructed to explore the association of SP-D levels and risk of death.

Results

Mortality rate after a 28-day was 32.42 %. Significant higher levels of SP-D were detected in A/H1N1 patients with fatal outcome (p < 0.05). After adjusting for confounding variables, levels of SP-D ≥250 ng/mL were associated with increased the risk of death (HR = 8.27, 95 % CI 1.1–64.1, p = 0.043).

Conclusions

Our results revealed that higher circulating levels of SP-D are associated with higher mortality risk in critically ill A/H1N1 patients. SP-D might be a predictive factor of poor outcomes in viral pneumonia.

Involvement of PI3K/Akt and p38 MAPK in the induction of COX-2 expression by bacterial lipopolysaccharide in murine adrenocortical cells

Previous studies from our laboratory demonstrated the involvement of COX-2 in the stimulation of steroid production by LPS in murine adrenocortical Y1 cells, as well as in the adrenal cortex of male Wistar rats. In this paper we analyzed signaling pathways involved in the induction of this key regulatory enzyme in adrenocortical cells and demonstrated that LPS triggers an increase in COX-2 mRNA levels by mechanisms involving the stimulation of reactive oxygen species (ROS) generation and the activation of p38 MAPK and Akt, in addition to the previously demonstrated increase in NFκB activity. In this sense we showed that: (1) inhibition of p38 MAPK or PI3K/Akt (pharmacological or molecular) prevented the increase in COX-2 protein levels by LPS, (2) LPS induced p38 MAPK and Akt phosphorylation, (3) antioxidant treatment blocked the effect of LPS on p38 MAPK phosphorylation and in COX-2 protein levels, (4) PI3K inhibition with LY294002 prevented p38 MAPK phosphorylation and, (5) the activity of an NFκB reporter was decreased by p38 MAPK or PI3K inhibition. These results suggest that activation of both p38 MAPK and PI3K/Akt pathways promote the stimulation of NFκB activity and that PI3K/Akt activity might regulate both p38 MAPK and NFκB signaling pathways. In summary, in this study we showed that in adrenal cells, LPS induces COX-2 expression by activating p38 MAPK and PI3K/Akt signaling pathways and that both pathways converge in the modulation of NFκB transcriptional activity.

Matrix stiffness corresponding to strictured bowel induces a fibrogenic response in human colonic fibroblasts

BACKGROUND

Crohn's disease is characterized by repeated cycles of inflammation and mucosal healing which ultimately progress to intestinal fibrosis. This inexorable progression toward fibrosis suggests that fibrosis becomes inflammation-independent and auto-propagative. We hypothesized that matrix stiffness regulates this auto-propagation of intestinal fibrosis.

METHODS

The stiffness of fresh ex vivo samples from normal human small intestine, Crohn's disease strictures, and the unaffected margin were measured with a microelastometer. Normal human colonic fibroblasts were cultured on physiologically normal or pathologically stiff matrices corresponding to the physiological stiffness of normal or fibrotic bowel. Cellular response was assayed for changes in cell morphology, α-smooth muscle actin staining, and gene expression.

RESULTS

Microelastometer measurements revealed a significant increase in colonic tissue stiffness between normal human colon and Crohn's strictures and between the stricture and adjacent tissue margin. In Ccd-18co cells grown on stiff matrices corresponding to Crohn's strictures, cellular proliferation increased. Pathologic stiffness induced a marked change in cell morphology and increased α-smooth muscle actin protein expression. Growth on a stiff matrix induced fibrogenic gene expression, decreased matrix metalloproteinase, and proinflammatory gene expression and was associated with nuclear localization of the transcriptional cofactor MRTF-A.

CONCLUSIONS

Matrix stiffness, representative of the pathologic stiffness of Crohn's strictures, activates human colonic fibroblasts to a fibrogenic phenotype. Matrix stiffness affects multiple pathways, suggesting that the mechanical properties of the cellular environment are critical to fibroblast function and may contribute to auto-propagation of intestinal fibrosis in the absence of inflammation, thereby contributing to the intractable intestinal fibrosis characteristic of Crohn's disease.

Role of PKC-α in NF-κB-MT1-MMP-mediated activation of proMMP-2 by TNF-α in pulmonary artery smooth muscle cells

We sought to evaluate the mechanism(s) associated with pro matrix metalloprotease 2 (proMMP-2) activation in bovine pulmonary artery smooth muscle cells. Preincubation of cells with anti-TNFR1 antibody prevented tumour necrosis factor-α (TNF-α)-induced proMMP-2 activation and increase in membrane type 1 matrix metalloprotease (MT1-MMP) expression as well as inhibition of tissue inhibitor of metalloproteinase 2 (TIMP-2) expression, indicating the role of TNFR1 receptor during TNF-α stimulation. Anti-MT1-MMP antibody abrogated proMMP-2 activation by TNF-α-stimulated cell membrane, suggesting the involvement of MT1-MMP in proMMP-2 activation. Induction of MT1-MMP expression in response to TNF-α occurs via activation of nuclear factor (NF)-κB on inhibitory κB kinase (IKK) activation and subsequently phosphorylation/degradation of IκB-α. Inhibition of protein kinase C (PKC)-α activity by Go6976 and PKC-α siRNA prevented TNF-α-induced IKK activity, IκB-α phosphorylation/degradation and NF-κB activation. Inhibition of PKC-α activity also prevented TNF-α-induced MT1-MMP expression and proMMP-2 activation as well as down regulation of TIMP-2 expression. Inhibition of IκB-α phosphorylation by PS-1145, an IKK selective inhibitor, prevented TNF-α-induced increase in MT1-MMP expression and proMMP-2 activation, which although did not alter inhibition of TIMP-2 expression. Overall, we unravelled a hitherto unknown mechanism of the involvement of PKC-α in proMMP-2 activation and inhibition of TIMP-2 expression by NF-κB-MT1-MMP-dependent and -independent pathway, respectively, during TNF-α stimulation in pulmonary artery smooth muscle cells.

Prostaglandin D2 induces apoptosis of human osteoclasts by activating the CRTH2 receptor and the intrinsic apoptosis pathway

Prostaglandin D(2) (PGD(2)) is a lipid mediator synthesized from arachidonic acid that directly activates two specific receptors, the D-type prostanoid (DP) receptor and chemoattractant receptor homologous molecule expressed on T-helper type 2 cells (CRTH2). PGD(2) can affect bone metabolism by influencing both osteoblast and osteoclast (OC) functions, both cells involved in bone remodeling and in in vivo fracture repair as well. The objective of the present study was to determine the effects of PGD(2), acting through its two specific receptors, on human OC apoptosis. Human OCs were differentiated in vitro from peripheral blood mononuclear cells in the presence of receptor activator for nuclear factor κB ligand (RANKL) and macrophage-colony stimulating factor (M-CSF), and treated with PGD(2), its specific agonists and antagonists. Treatment with PGD(2) for 24hours in the presence of naproxen (10μM) to inhibit endogenous prostaglandin production increased the percentage of apoptotic OCs in a dose-dependent manner, as did the specific CRTH2 agonist compound DK-PGD(2) but not the DP agonist compound BW 245C. In the absence of naproxen, the CRTH2 antagonist compound CAY 10471 reduced OC apoptosis rate but the DP antagonist BW A868C had no effect. The induction of PGD(2)-CRTH2 dependent apoptosis was associated with the activation of caspase-9, but not caspase-8, leading to caspase-3 cleavage. These data show that PGD(2) induces human OC apoptosis through activation of CRTH2 and the apoptosis intrinsic pathway.

Igf2bp1 is required for full induction of Ptgs2 mRNA in colonic mesenchymal stem cells in mice

BACKGROUND & AIMS

Prostaglandin-endoperoxide synthase (Ptgs)2 is an enzyme involved in prostaglandin production during the response to mucosal damage. Its expression is regulated, in part, by messenger RNA (mRNA)-binding proteins that control the stability of Ptgs2 mRNA. We used a precise system of colonic injury and repair to identify Ptgs2 mRNA-binding proteins.

METHODS

We used endoscopy-guided mucosal excision to create focal injury sites in colons of mice. Wound beds from wild-type, Ptgs2(-/-), Ptgs2(+/-), and Myd88(-/-) mice were analyzed at 2-day intervals after injury for aspects of repair and Ptgs2 expression. We used cultured colonic mesenchymal stem cells (cMSCs) that express Ptgs2 to identify and analyze molecules that regulate Ptgs2 expression.

RESULTS

Ptgs2(-/-) mice had defects in wound repair, validating the biopsy technique as a system to study the regulation of Ptgs2. Ptgs2(+/-) mice had similar defects in wound healing, so full induction of Ptgs2 is required for wound repair. In wild-type mice, levels of Ptgs2 mRNA increased significantly in the wound bed 2 and 4 days after injury; the highest levels of Ptgs2 were observed in cMSCs. In a functional short hairpin RNA knockdown screen, we identified Igf2bp1, a VICKZ (Vg1 RNA binding protein, Insulin-like growth factor II mRNA binding protein 1, Coding region determinant-binding protein, KH domain containing protein overexpressed in cancer, and Zipcode-binding protein-1) mRNA-binding protein, as a regulator of Ptgs2 expression in cMSCs. Igf2bp1 also interacted physically with Ptgs2 mRNA. Igf2bp1 expression was induced exclusively in wound-bed cMSCs, and full induction of Ptgs2 and Igf2bp1 during repair required Myd88.

CONCLUSIONS

We identified Igf2bp1 as a regulator of Ptgs2 mRNA in mice. Igf2bp1 is required for full induction of Ptgs2 mRNA in cMSCs.

Rottlerin enhances IL-1β-induced COX-2 expression through sustained p38 MAPK activation in MDA-MB-231 human breast cancer cells

Cyclooxygenase-2 (COX-2) is an important enzyme in inflammation. In this study, we investigated the underlying molecular mechanism of the synergistic effect of rottlerin on interleukin1β (IL-1β)-induced COX-2 expression in MDA-MB-231 human breast cancer cell line. Treatment with rottlerin enhanced IL-1β-induced COX-2 expression at both the protein and mRNA levels. Combined treatment with rottlerin and IL-1β significantly induced COX-2 expression, at least in part, through the enhancement of COX-2 mRNA stability. In addition, rottlerin and IL-1β treatment drove sustained activation of p38 Mitogen-activated protein kinase (MAPK), which is involved in induced COX-2 expression. Also, a pharmacological inhibitor of p38 MAPK (SB 203580) and transient transfection with inactive p38 MAPK inhibited rottlerin and IL-1β-induced COX-2 upregulation. However, suppression of protein kinase C δ (PKC δ) expression by siRNA or overexpression of dominant-negative PKC δ (DN-PKC-δ) did not abrogate the rottlerin plus IL-1β-induced COX-2 expression. Furthermore, rottlerin also enhanced tumor necrosis factor-α (TNF-α), phorbol myristate acetate (PMA), and lipopolysaccharide (LPS)-induced COX-2 expression. Taken together, our results suggest that rottlerin causes IL-1β-induced COX-2 upregulation through sustained p38 MAPK activation in MDA-MB-231 human breast cancer cells.

miRNA studies in in vitro and in vivo activated hepatic stellate cells

AIM

To understand which and how different miRNAs are implicated in the process of hepatic stellate cell (HSC) activation.

METHODS

We used microarrays to examine the differential expression of miRNAs during in vitro activation of primary HSCs (pHSCs). The transcriptome changes upon stable transfection of rno-miR-146a into an HSC cell line were studied using cDNA microarrays. Selected differentially regulated miRNAs were investigated by quantitative real-time polymerase chain reaction during in vivo HSC activation. The effect of miRNA mimics and inhibitor on the in vitro activation of pHSCs was also evaluated.

RESULTS

We found that 16 miRNAs were upregulated and 26 were downregulated significantly in 10-d in vitro activated pHSCs in comparison to quiescent pHSCs. Overexpression of rno-miR-146a was characterized by marked upregulation of tissue inhibitor of metalloproteinase-3, which is implicated in the regulation of tumor necrosis factor-α activity. Differences in the regulation of selected miRNAs were observed comparing in vitro and in vivo HSC activation. Treatment with miR-26a and 29a mimics, and miR-214 inhibitor during in vitro activation of pHSCs induced significant downregulation of collagen type I transcription.

CONCLUSION

Our results emphasize the different regulation of miRNAs in in vitro and in vivo activated pHSCs. We also showed that miR-26a, 29a and 214 are involved in the regulation of collagen type I mRNA.

miRNA studies in in vitro and in vivo activated hepatic stellate cells

AIM

To understand which and how different miRNAs are implicated in the process of hepatic stellate cell (HSC) activation.

METHODS

We used microarrays to examine the differential expression of miRNAs during in vitro activation of primary HSCs (pHSCs). The transcriptome changes upon stable transfection of rno-miR-146a into an HSC cell line were studied using cDNA microarrays. Selected differentially regulated miRNAs were investigated by quantitative real-time polymerase chain reaction during in vivo HSC activation. The effect of miRNA mimics and inhibitor on the in vitro activation of pHSCs was also evaluated.

RESULTS

We found that 16 miRNAs were upregulated and 26 were downregulated significantly in 10-d in vitro activated pHSCs in comparison to quiescent pHSCs. Overexpression of rno-miR-146a was characterized by marked upregulation of tissue inhibitor of metalloproteinase-3, which is implicated in the regulation of tumor necrosis factor-α activity. Differences in the regulation of selected miRNAs were observed comparing in vitro and in vivo HSC activation. Treatment with miR-26a and 29a mimics, and miR-214 inhibitor during in vitro activation of pHSCs induced significant downregulation of collagen type I transcription.

CONCLUSION

Our results emphasize the different regulation of miRNAs in in vitro and in vivo activated pHSCs. We also showed that miR-26a, 29a and 214 are involved in the regulation of collagen type I mRNA.

Counteracting effect of TRPC1-associated Ca2+ influx on TNF-α-induced COX-2-dependent prostaglandin E2 production in human colonic myofibroblasts

TNF-α-NF-κB signaling plays a central role in inflammation, apoptosis, and neoplasia. One major consequence of this signaling in the gut is increased production of prostaglandin E(2) (PGE(2)) via cyclooxygenase-2 (COX-2) induction in myofibroblasts, which has been reported to be dependent on Ca(2+). In this study, we explored a potential role of canonical transient receptor potential (TRPC) proteins in this Ca(2+)-mediated signaling using a human colonic myofibroblast cell line CCD-18Co. In CCD-18Co cell, treatment with TNF-α greatly enhanced Ca(2+) influx induced by store depletion along with increased cell-surface expression of TRPC1 protein (but not of the other TRPC isoforms) and induction of a Gd(3+)-sensitive nonselective cationic conductance. Selective inhibition of TRPC1 expression by small interfering RNA (siRNA) or functionally effective TRPC1 antibody targeting the near-pore region of TRPC1 (T1E3) antagonized the enhancement of store-dependent Ca(2+) influx by TNF-α, whereas potentiated TNF-α induced PGE(2) production. Overexpression of TRPC1 in CCD-18Co produced opposite consequences. Inhibitors of NF-κB (curcumin, SN-50) attenuated TNF-α-induced enhancement of TRPC1 expression, store-dependent Ca(2+) influx, and COX-2-dependent PGE(2) production. In contrast, inhibition of calcineurin-nuclear factor of activated T-cell proteins (NFAT) signaling by FK506 or NFAT Activation Inhibitor III enhanced the PGE(2) production without affecting TRPC1 expression and the Ca(2+) influx. Finally, the suppression of store-dependent Ca(2+) influx by T1E3 antibody or siRNA knockdown significantly facilitated TNF-α-induced NF-κB nuclear translocation. In aggregate, these results strongly suggest that, in colonic myofibroblasts, NF-κB and NFAT serve as important positive and negative transcriptional regulators of TNF-α-induced COX-2-dependent PGE(2) production, respectively, at the downstream of TRPC1-associated Ca(2+) influx.

Post-transcriptional gene regulation following exposure of osteoarthritic human articular chondrocytes to hyperosmotic conditions

OBJECTIVE

Osmolarity is a major biophysical regulator of chondrocyte function. Modulation of chondrocytic marker gene expression occurs at the post-transcriptional level following exposure of human articular chondrocytes (HAC) to hyperosmotic conditions. This study aims to further characterise the post-transcriptional response of HAC to hyperosmolarity.

METHODS

Gene expression and microRNA (miRNA) levels in freshly isolated HAC after 5h under control or hyperosmotic conditions were measured using microarrays. Regulated genes were checked for the presence of AU rich elements (AREs) in their 3' untranslated regions (3'UTR), whilst gene ontology was examined using Ingenuity Pathway Analysis (IPA). RNA decay rates of candidate ARE-containing genes were determined in HAC using actinomycin D chase experiments and the involvement of the p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinases 1 and 2 (ERK1/2) pathways were investigated using pharmacological inhibitors.

RESULTS

Hyperosmolarity led to the regulation of a wide variety of genes. IPA identified enrichment of genes involved with cell stress responses, cell signalling and transforming growth factor β (TGFβ) signalling. Importantly, upregulated genes were over-represented with those containing AREs, and RNA decay analysis demonstrated that many of these were regulated post-transcriptionally by hyperosmolarity in HAC. Analysis of miRNA levels in HAC indicated that they are only modestly regulated by hyperosmotic conditions, whilst inhibitor studies showed that p38 MAPK and ERK1/2 were able to block hyperosmotic induction of many of these genes.

CONCLUSION

Through microarray and bioinformatics analysis we have identified genes which are post-transcriptionally regulated in HAC following exposure to hyperosmotic conditions. These genes have a range of functions, and their regulation involves transduction through the p38 MAPK and ERK1/2 pathways. Interestingly, our results suggest that miRNA regulation is not key to the process. Overall, this work illustrates the range of processes regulated in chondrocytes by changes in their osmotic environment, and underlines the importance of post-transcriptional mRNA regulation to chondrocyte function.

Mechanisms of the anti-cancer and anti-inflammatory actions of vitamin D

Calcitriol, the hormonally active form of vitamin D, is being evaluated in clinical trials as an anti-cancer agent. Calcitriol exerts multiple anti-proliferative, pro-apoptotic, and pro-differentiating actions on various malignant cells and retards tumor growth in animal models of cancer. Calcitriol also exhibits several anti-inflammatory effects including suppression of prostaglandin (PG) action, inhibition of p38 stress kinase signaling, and the subsequent production of pro-inflammatory cytokines and inhibition of NF-κB signaling. Calcitriol also decreases the expression of aromatase, the enzyme that catalyzes estrogen synthesis in breast cancer, both by a direct transcriptional repression and indirectly by reducing PGs, which are major stimulators of aromatase transcription. Other important effects include the suppression of tumor angiogenesis, invasion, and metastasis. These calcitriol actions provide a basis for its potential use in cancer therapy and chemoprevention. We summarize the status of trials involving calcitriol and its analogs, used alone or in combination with known anti-cancer agents.

Development of an enzyme-linked immunosorbent assay for measurement of rat pulmonary surfactant protein D using monoclonal antibodies

Surfactant protein D (SP-D) has been used as a biomarker of lung inflammation. In rat, several types of enzyme-linked immunosorbent assay (ELISA) using polyclonal antibodies have been reported. The purpose of this study was the development of a sensitive ELISA for rat SP-D using monoclonal antibodies. The authors developed a sandwich ELISA using monoclonal antibodies that were obtained by immunizing with purified rat SP-D. The ELISA was evaluated by performance tests. Furthermore, concentrations of serum SP-D were measured in normal control and bleomycin-treated rats. The working range of ELISA was between 0.47 and 30 ng/mL. Different concentrations of added SP-D were recovered, between 94.1% and 102.8%. Serum SP-D levels of bleomycin-treated rats were significantly higher than those of normal rats. In conclusion, this newly developed ELISA for rat SP-D using monoclonal antibodies is applicable for research on the mechanism and therapy of lung injury.

Claude H. Organ, Jr. memorial lecture: splanchnic hypoperfusion provokes acute lung injury via a 5-lipoxygenase-dependent mechanism

Postinjury multiple organ failure (MOF) is the net result of a dysfunctional immune response to injury characterized by a hyperactive innate system and a suppressed adaptive system. Acute lung injury (ALI) is the first clinical manifestation of organ failure, followed by renal and hepatic dysfunction. Circulatory shock is integral in the early pathogenesis of MOF, and the gut has been invoked as the motor of MOF. Mesenteric lymph is recognized as the mechanistic link between splanchnic ischemia/reperfusion and distant organ dysfunction, but the specific mediators remain to be defined. Current evidence suggests the lipid fraction of postshock mesenteric lymph is central in the etiology of ALI. Specifically, our recent work suggests that intestinal phospholipase A2 generated arachidonic acid and its subsequent 5-lipoxygenase products are essential in the pathogenesis of ALI. Proteins conveyed via postshock mesenteric lymph also may have an important role. Elucidating these mediators and the timing of their participation in pulmonary inflammation is critical in translating our current knowledge to new therapeutic strategies at the bedside.

Acute lung injury induces cardiovascular dysfunction: effects of IL-6 and budesonide/formoterol

Acute lung injury (ALI) is associated with systemic inflammation and cardiovascular dysfunction. IL-6 is a biomarker of this systemic response and a predictor of cardiovascular events, but its possible causal role is uncertain. Inhaled corticosteroids and long-acting β2 agonists (ICS/LABA) down-regulate the systemic expression of IL-6, but whether they can ameliorate the cardiovascular dysfunction related to ALI is uncertain. We sought to determine whether IL-6 contributes to the cardiovascular dysfunction related to ALI, and whether budesonide/formoterol ameliorates this process. Wild-type mice were pretreated for 3 hours with intratracheal budesonide, formoterol, or both, before LPS was sprayed into their tracheas. IL-6-deficient mice were similarly exposed to LPS. Four hours later, bronchoalveolar lavage fluid (BALF) and serum were collected, and endothelial and cardiac functions were measured, using wire myography of the aortic tissue and echocardiography, respectively. LPS significantly impaired vasodilatory responses to acetylcholine (P < 0.001) and cardiac output (P = 0.002) in wild-type but not IL-6-deficient mice. Intratracheal instillations of exogenous IL-6 into IL-6-deficient mice restored these impairments (vasodilatory responses to acetylcholine, P = 0.005; cardiac output, P = 0.025). Pretreatment with the combination of budesonide and formoterol, but not either alone, ameliorated the vasodilatory responses to acetylcholine (P = 0.018) and cardiac output (P < 0.001). These drugs also attenuated the rise in the systemic expression of IL-6 (P < 0.05) related to LPS. IL-6 contributes to the cardiovascular dysfunction related to LPS, and pretreatment with budesonide/formoterol reduces the systemic expression of IL-6 and improves cardiovascular dysfunction. ICS/LABA may reduce acute cardiovascular events related to ALI.

An interaction between L-prostaglandin D synthase and arrestin increases PGD2 production

L-type prostaglandin synthase (L-PGDS) produces PGD(2), a lipid mediator involved in neuromodulation and inflammation. Here, we show that L-PGDS and arrestin-3 (Arr3) interact directly and can be co-immunoprecipitated endogenously from MG-63 osteoblasts. Perinuclear L-PGDS/Arr3 co-localization is observed in PGD(2)-producing MG-63 cells and is induced by the addition of the L-PGDS substrate or co-expression of COX-2 in HEK293 cells. Inhibition of L-PGDS activity in MG-63 cells triggers redistribution of Arr3 and L-PGDS to the cytoplasm. Perinuclear localization of L-PGDS is detected in wild-type mouse embryonic fibroblasts (MEFs) but is more diffused in MEFs-arr-2(-/-)-arr-3(-/-). Arrestin-3 promotes PGD(2) production by L-PGDS in vitro. IL-1β-induced PGD(2) production is significantly lower in MEFs-arr-2(-/-)-arr-3(-/-) than in wild-type MEFs but can be rescued by expressing Arr2 or Arr3. A peptide corresponding to amino acids 86-100 of arrestin-3 derived from its L-PGDS binding domain stimulates L-PGDS-mediated PGD(2) production in vitro and in MG-63 cells. We report the first characterization of an interactor/modulator of a PGD(2) synthase and the identification of a new function for arrestin, which may open new opportunities for improving therapies for the treatment of inflammatory diseases.

NF-kappaB-dependent anti-inflammatory activity of urolithins, gut microbiota ellagic acid-derived metabolites, in human colonic fibroblasts

Previous studies have reported the anti-inflammatory properties of pomegranate extracts, suggesting that ellagitannins (ET) and ellagic acid (EA) are the main anti-inflammatory compounds. However, both ET and EA are metabolised in vivo by the gut microbiota to yield urolithins (Uro) which can be found in the gut and in systemic bloodstream. The present study was carried out to evaluate the individual effect of EA and their microbiota-derived metabolites Uro on colon fibroblasts upon IL-1beta treatment as an in vitro inflammation model. Uro-A and Uro-B (10 microm) inhibited PGE2 production (85 and 40 %, respectively) after IL-1beta stimulation, whereas EA did not show any effect. Uro-A, but not Uro-B, down-regulated cyclo-oxygenase-2 (COX-2) and microsomal PGE synthase-1 (mPGES-1) mRNA expression and protein levels. Both Uro inhibited NF-kappaB translocation to nucleus. Slight but significant effects were found in the activation of mitogen-activated protein kinase (MAPK) pathways. Uro-A lowered c-Jun N-terminal kinase phosphorylation state, and both Uro inhibited p38 activation. No metabolites derived from Uro or EA were found in the cell media upon incubation of EA or Uro with the cells, and only traces of the compounds were found inside the cells. The present results suggest that Uro, mainly Uro-A, are the main compounds that are responsible for the pomegranate anti-inflammatory properties. The mechanism of action implicated seems to be via the inhibition of activation of NF-kappaB and MAPK, down-regulation of COX-2 and mPGES-1 expressions, and consequently,via the reduction of PGE2 production. Taking into account that Uro did not enter the cells, a competitive binding for IL-1beta membrane receptor cannot be discarded.

Endogenous N-acyl-dopamines induce COX-2 expression in brain endothelial cells by stabilizing mRNA through a p38 dependent pathway

Cerebral microvascular endothelial cells play an active role in maintaining cerebral blood flow, microvascular tone and blood brain barrier (BBB) functions. Endogenous N-acyl-dopamines like N-arachidonoyl-dopamine (NADA) and N-oleoyl-dopamine (OLDA) have been recently identified as a new class of brain neurotransmitters sharing endocannabinoid and endovanilloid biological activities. Endocannabinoids are released in response to pathogenic insults and may play an important role in neuroprotection. In this study we demonstrate that NADA differentially regulates the release of PGE(2) and PGD(2) in the microvascular brain endothelial cell line, b.end5. We found that NADA activates a redox-sensitive p38 MAPK pathway that stabilizes COX-2 mRNA resulting in the accumulation of the COX-2 protein, which depends on the dopamine moiety of the molecule and that is independent of CB(1) and TRPV1 activation. In addition, NADA inhibits the expression of mPGES-1 and the release of PGE(2) and upregulates the expression of L-PGD synthase enhancing PGD(2) release. Hence, NADA and other molecules of the same family might be included in the group of lipid mediators that could prevent the BBB injury under inflammatory conditions and our findings provide new mechanistic insights into the anti-inflammatory activities of NADA in the central nervous system and its potential to design novel therapeutic strategies to manage neuroinflammatory diseases.

Involvement of protein kinase C in IL-1beta-induced expression of cyclooxygenase-2 in human gingival fibroblasts

Interleukin-1beta (IL-1beta) stimulates expression of the highly inducible enzyme cyclooxygenase-2 (COX-2) via activation of nuclear factor kappaB (NFkappaB), and consequently provokes prostaglandin E(2) (PGE(2)) synthesis, which induces inflammatory responses. In this study, the contribution of protein kinase C (PKC) to IL-1beta-induced PGE(2) synthesis in human gingival fibroblasts was investigated. The PKC activator phorbol 12-myristate 13-acetate (PMA) stimulated PGE(2) release and COX-2 mRNA expression, as shown in human gingival fibroblasts stimulated by IL-1beta. However, PMA showed only a weak effect on the formation of COX-2-NFkappaB DNA-protein complex, whereas IL-1beta had a clearly stimulatory effect. In cells in which PMA-dependent PKC was down-regulated, PMA failed to induce the formation of NFkappaB DNA-protein complex and reduced the release of PMA-induced PGE(2), whereas IL-1beta stimulated the formation of COX-2-NFkappaB DNA-protein complex and PGE(2) release. The atypical PKC (aPKC) inhibitor Gö6983 clearly suppressed the formation of COX-2-NFkappaB DNA-protein complex and PGE(2) release stimulated by IL-1beta but not the inhibitor of conventional PKC (cPKC) and the novel PKC (nPKC) inhibitor Gö6976. These observations suggest that aPKC is involved in IL-1beta-induced PGE(2) synthesis, which is controlled by transcription of the COX-2 gene via the NFkappaB-dependent pathway in human gingival fibroblasts.

Protein kinase D mediates synergistic expression of COX-2 induced by TNF-{alpha} and bradykinin in human colonic myofibroblasts

Myofibroblasts have recently been identified as major mediators of tumor necrosis factor-alpha (TNF-alpha)-associated colitis, but the precise mechanism(s) involved remains incompletely understood. In particular, the possibility that TNF-alpha signaling cross talks with other proinflammatory mediators, including bradykinin (BK), has not been examined in these cells. Here we show that treatment of 18Co cells, a model of human colonic myofibroblasts, with BK and TNF-alpha induced striking synergistic COX-2 protein expression that was paralleled by increases in the levels of transcripts encoding COX-2 and microsomal prostaglandin E synthase 1 (mPGES-1) and by the production of PGE(2). COX-2 expression in 18Co cells treated with BK and TNF-alpha was prevented by the B(2) BK receptor antagonist HOE-140, the preferential protein kinase C (PKC) inhibitors Ro31-8220 and GF-109203X, and Gö-6976, an inhibitor of conventional PKCs and protein kinase D (PKD). In a parallel fashion, TNF-alpha, while having no detectable effect on the activation of PKD when added alone, augmented PKD activation induced by BK, as measured by PKD phosphorylation at its activation loop (Ser(744)) and autophosphorylation site (Ser(916)). BK-induced PKD activation was also inhibited by HOE-140, Ro31-8220, and Gö-6976. Transfection of 18Co cells with small interfering RNA targeting PKD completely inhibited the synergistic increase in COX-2 protein in response to BK and TNF-alpha, demonstrating, for the first time, a critical role of PKD in the pathways leading to synergistic expression of COX-2. Our results imply that cross talk between TNF-alpha and BK amplifies a PKD phosphorylation cascade that mediates synergistic COX-2 expression in colonic myofibroblasts. It is plausible that PKD increases COX-2 expression in colonic myofibroblasts to promote an inflammatory microenvironment that supports tumor growth.

Lipopolysaccharide activates innate immune responses in murine intestinal myofibroblasts through multiple signaling pathways

Myofibroblasts (MF) play an important role in intestinal wound healing. A compromised epithelial barrier exposes intestinal subepithelial MF to luminal bacterial products. However, responses of murine intestinal MF to bacterial adjuvants and potential roles of intestinal MF in innate immune responses are not well defined. Our aims in this study were to determine innate immune responses and intracellular signaling pathways of intestinal MF exposed to LPS, a prototypic Toll-like receptor (TLR) ligand. Expression of TLR4 in primary murine intestinal MF cultures was confirmed by RT-PCR and Western blotting. LPS-induced secretion of prostaglandin E2 (PGE2), interleukin (IL)-6, and keratinocyte-derived chemokines (KC) was measured by ELISA. Intracellular responses to LPS were assessed by Western blotting for NF-kappaB p65, Ikappa-Balpha, Akt, p38 MAP kinase, and cyclooxygenase-2 (COX-2). LPS induced rapid phosphorylation of NF-kappaB p65, Akt, and p38 MAPK and degradation of Ikappa-Balpha. LPS induced expression of COX-2 and secretion of PGE2 (2.0+/-0.8-fold induction vs. unstimulated cells), IL-6 (6.6+/-0.4-fold induction), and KC (12.5+/-0.4-fold induction). Inhibition of phosphoinositide-3 (PI3)-kinase, p38 MAPK, or NF-kappaB pathways reduced LPS-induced PGE2, IL-6, and KC secretion. These studies show that primary murine intestinal MF respond to LPS, evidenced by activation of NF-kappaB, PI3-kinase, and MAPK signaling pathways and secretion of proinflammatory molecules. Inhibition of these pathways attenuated LPS-dependent PGE2, IL-6, and KC production, indicating that LPS activates MF by multiple signaling pathways. These data support the hypothesis that MF are a component of the innate immune system and may exert paracrine effects on adjacent epithelial and immune cells by responding to luminal bacterial adjuvants.

Preventive effects of curcumin on different aspiration material-induced lung injury in rats

PURPOSE

We have studied whether curcumin protects different pulmonary aspiration material-induced lung injury in rats.

MATERIALS AND METHODS

The experiments were designed in 60 Sprague-Dawley rats, randomly allotted into one of six groups (n=10): normal saline (NS, control), enteral formula (Biosorb Energy Plus, BIO), hydrochloric acid (HCl), NS+curcumin-treated, BIO+curcumin-treated, and HCl+curcumin-treated. NS, BIO, HCl were injected in to the lungs. The rats received curcumin twice daily only for 7 days. Seven days later, both lungs in all groups were examined histopathologically, immunohistochemically, and biochemically. Histopathologic examination was performed according to the presence of peribronchial inflammatory cell infiltration, alveolar septal infiltration, alveolar edema, alveolar exudate, alveolar histiocytes, interstitial fibrosis, granuloma, and necrosis formation. Immunohistochemical assessments were examined for the activity of inducible nitric oxide synthase (iNOS) and the expression of surfactant protein D (SP-D). Malondialdehyde (MDA), hydroxyproline (HP), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activity were measured in the lung tissue.

RESULTS

Our findings show that curcumin inhibits the inflammatory response reducing significantly (P<0.05) all histopathological parameters in different pulmonary aspiration models. Pulmonary aspiration significantly increased the tissue HP content, MDA levels and decreased the antioxidant enzyme (SOD, GSH-Px) activities. Curcumin treatment significantly decreased the elevated tissue HP content, and MDA levels and prevented inhibition of SOD, and GSH-Px enzymes in the tissues. Furthermore, our data suggest that there is a significant reduction in the activity of iNOS and a rise in the expression of SP-D in lung tissue of different pulmonary aspiration models with curcumin therapy.

CONCLUSION

Our findings support the use of curcumin as a potential therapeutic agent in acute lung injury.

Sphingosine-1-phosphate enhances IL-1{beta}-induced COX-2 expression in mouse intestinal subepithelial myofibroblasts

Intestinal subepithelial myofibroblasts (SEMFs) is a specific population of cells involved in intestinal inflammation and carcinogenesis via an elaborate network of cytokines, chemokines and other inflammatory factors, including PGE(2). Sphingosine-1-phosphate (S1P) has been implicated as an important mediator of inflammation and cancer and in certain cell types increases cyclooxygenase-2 (COX-2) expression. In the present study, we aimed to assess involvement of S1P in COX-2 expression by SEMFs. Primary SEMFs were obtained from C57BL/6J mouse and their identity was verified by fluorescent staining of specific marker proteins. Expression of S1P receptors 1, 2, 3 and sphingosine kinases 1 and 2 in SEMFs were determined by RT-PCR analysis. COX-2 expression and PGE(2) production were assayed by Western blotting and ELISA, respectively. COX-2 mRNA stability was assayed by Northern blotting. S1P produced dose-dependent increase in COX-2 expression, resulting in increased PGE(2) release from SEMFs. Using specific inhibitors, we show that actions of p38, ERK, IKK, and PKC were involved in S1P-induced COX-2 expression. On the other hand, p38 and PKC had lesser roles in IL-1beta-induced COX-2 expression. Inhibition of sphingosine kinase to block S1P production did not affect IL-1beta-induced COX-2 expression, but S1P amplified IL-1beta-induced p38 activation and COX-2 expression. PKC inhibition blocked S1P amplified COX-2 expression. S1P addition increased COX-2 mRNA stability. In SEMFs, S1P amplifies IL-1beta-induced COX-2 expression through increased mRNA stability. These observations point to involvement of S1P in activation of SEMFs that may contribute to intestinal inflammation and carcinogenesis.

Novel p38 MAP kinase inhibitor R-130823 suppresses IL-6, IL-8 and MMP-13 production in spheroid culture of human synovial sarcoma cell line SW 982

Synovial hyperplasia is a hallmark of rheumatoid arthritis (RA) and is regarded as a major destructive element of articular bone and cartilage. This pathological process is accompanied by the production of proinflammatory cytokines, prostaglandin E(2) (PGE(2)), and matrix metalloproteinases (MMPs) in synoviocytes. We studied the spontaneous production of these substances in RA synoviocytes in spheroid culture. Synovial sarcoma cell line SW 982 formed a single spheroid in non-adherent culture plates. It produced interleukin (IL)-1beta, IL-6, IL-8, PGE(2), MMP-2 and MMP-13. Neither the addition of integrin antagonizing oligopeptide (GRGDSP) nor that of vitronectin receptor inhibitor SB-265123 to the culture inhibited any production. Phosphorylation of p38 mitogen-activated protein (MAP) kinase was observed during the culture. A novel p38 MAP kinase inhibitor, R-130823, inhibited the release of IL-6, IL-8 and MMP-13 in a concentration-dependent manner, but not that of IL-1beta or MMP-2. Real-time RT-PCR analysis demonstrated that IL-6, IL-8 and MMP-13 were inhibited at the transcriptional level. R-130823 did not affect the production of PGE(2) in spheroid culture, while the addition of R-130823 suppressed IL-1beta-induced PGE(2) synthesis in monolayer culture of SW 982 cells. The results suggest that spheroid culture induced proinflammatory factors and MMPs in signaling pathways both dependent and independent of p38 MAP kinase.

ISSLS prize winner: repeated disc injury causes persistent inflammation

STUDY DESIGN

An in vivo rat model of disc degeneration with emphasis on characterizing acute and chronic cytokine production.

OBJECTIVE

To compare the morphologic and proinflammatory response between a single and triple-stab injury in attempts to establish mechanisms of chronic disc inflammation.

SUMMARY OF BACKGROUND DATA

The features that distinguish physiologic (asymptomatic) from pathologic (symptomatic) degeneration are unclear. Epidemiologic evidence suggests that cumulative damage and elevated disc cytokine levels may be linked to increased low back pain rates. Although acute injury stimulates a healing response that includes transient cytokine production, repetitive damage may be necessary to trigger the persistent inflammation suspected to underlie chronic pain.

METHODS

Tail discs were exposed surgically and stabbed with a number 11 blade. During the subsequent acute healing phase, triple-stab discs were percutaneously injured with a 23-gauge needle at day 3 and then again at day 6 after the initial blade incision. Cytokine (IL-1 beta, IL-6, IL-8, and TNF-alpha) production was quantified using enzyme linked immunosorbent assay, and, in addition to MAPK signaling pathways (phosphorylated forms of ERK, JNK, and p38), was localized by immunohistochemistry. Disc architecture was evaluated using histology.

RESULTS

Both single-stab and triple-stab discs degenerated with time, yet degeneration was more severe with repeated injury where nuclear proteoglycan was replaced by disorganized collagen. Four days after single-stab, there was a transient peak in IL-1 beta and IL-8 production that was localized to the wound track and associated granulation tissue. By contrast, triple-stab induced an activated annular fibroblast phenotype (p38 positive) that caused a prolonged, diffuse inflammatory response with elevated levels of TNF-alpha, IL-1 beta, and IL-8 up to 28 days after injury. Disc inflammation was accompanied by reactive changes in the adjacent vertebral marrow spaces that was initially lytic at day 4, becoming sclerotic by day 56.

CONCLUSION

Our results demonstrate that repeated injury during active healing leads to persistent inflammation and enhanced disc degeneration. These data support the premise that damage accumulation and its associated inflammation may distinguish pathologic from physiologic disc degeneration. In the future, this triple-stab model may be useful to evaluate the efficacy of anti-inflammatory low back pain treatments.

HETEs enhance IL-1-mediated COX-2 expression via augmentation of message stability in human colonic myofibroblasts

Proinflammatory cytokines and eicosanoids are central players in intestinal inflammation. IL-1, a key cytokine associated with intestinal mucosal inflammation, induces COX-2 expression in human colonic myofibroblasts (CMF) and increased prostaglandin E(2) secretion is associated with inflammatory bowel disease (IBD) and colorectal cancer (CRC). We have previously demonstrated that IL-1alpha-induced cyclooxygenase-2 (COX-2) expression is the result of NF-kappaB- and ERK-mediated transcription, as well as COX-2 message stabilization, which depends on p38, MAPKAPK-2 (MK-2) and human antigen R (HuR) RNA binding protein activation. Lipoxygenase (LOX)-derived hydroxyeicosatetraenoic acids (HETEs) are elevated in IBD and colonic adenomas and "cross talk" has been observed between the COX and LOX pathways. Since COX-2 expression is primarily in CMFs in colonic adenomas, we examined the impact of LOX metabolites, particularly HETEs, on IL-1alpha-induced COX-2 expression in human CMFs. Although 5(S)-, 12(R)-, and 15(S)-HETEs alone had little to no effect on COX-2 expression, they enhanced IL-1-mediated COX-2 expression 3.6 +/- 0.5-fold. Studies utilizing heterogeneous nuclear RNA amplification and 5,6-dichloro-beta-d-ribofuranosylbenzimidazole treatment were undertaken to measure COX-2 transcription and message stabilization, respectively. We found that HETEs enhanced IL-1-induced COX-2 mRNA levels in CMF as the result of increased p38, MK-2, and HuR activity, increasing message stability greater than that observed with IL-1 alone. Thus HETEs can act synergistically with IL-1alpha to induce COX-2 expression in human CMFs. HETEs may play a role in both colonic inflammation and in increasing the risk of CRC in IBD independently and via induction of COX-2-mediated prostaglandin secretion.

Reduced expression of microenvironmental Th1 cytokines accompanies adenomas-carcinomas sequence of colorectum

Cytokines have been suggested to be key factors in modulating immune response against tumorigenesis in the microenvironment. Therefore, characterization of cytokine expression along the colorectal adenoma-carcinoma sequence may add important information for understanding the immune-related mechanisms of the development of colorectal carcinoma (CRC). In this study, biopsies from 32 patients with colorectal adenoma (CRA), 20 patients with CRC and 18 healthy controls were examined. Cytokine gene expressions of interleukin-4 (IL-4), IL-10, tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma and its upstream inducers (IL-12A and IL-18) were measured at messenger RNA (mRNA) level with quantitative real-time PCR (Q-PCR). Cytokine expressing cells were characterized using immunohistochemistry (IHC). A distinct different cytokine profile between adenoma and CRC was observed: the Th1 cytokines (IFN-gamma, TNF-alpha, IL-12A and IL-18) were increased in local tissues of CRA and decreased in CRC. Consistent with the quantitative cytokine data, IHC examinations revealed slightly increased densities of Th1 cytokine-expressing cells in CRA and a remarkably decreased density of the Th1 cells in CRC. In CRA, the cytokine-expressing cells were highly polarized to the subepithelial stroma while the cells were evenly distributed through the stroma in CRC. In conclusion, distinct changes in the Th1 cytokine profile appear along the colorectal adenoma-carcinoma sequence. This may reflect a change in the host immune regulatory function in the adenoma-carcinoma sequence.

Prostaglandin E2 induces the expression of IL-1alpha in colon cancer cells

PGE(2) has been shown to exert pro-oncogenic effects in colorectal neoplasia through producing autocrine or paracrine growth factors. In the present study, we demonstrate that PGE(2) induced the expression of IL-1alpha in colon cancer cells, which plays critical roles in tumor metastasis and neoangiogenesis in a variety of cancers. PGE(2) increased the levels of both IL-1alpha mRNA and protein, suggesting a positive feedback loop between the IL-1 pathway and PGE(2) signaling. Mechanistically, PGE(2) induced the expression of IL-1alpha at both transcriptional and posttranscriptional levels. PGE(2) stimulated the transcriptional activity of the IL-1alpha promoter and significantly stabilized IL-1alpha mRNA. Moreover, we show that IL-1alpha enhanced colorectal neoplasia, stimulating cell migration and neoangiogenesis. Knockdown of the expression of IL-1alpha by small-interfering RNA resulted in a reduction of vascular endothelial growth factor secretion in colon cancer cells and an inhibition of tube formation by HUVECs. Thus, our results suggest that PGE(2) induces the expression of proinflammatory cytokine IL-1alpha, which may potentially enhance the proneoplastic actions of the cyclooxygenase-2/PGE(2) signaling pathway.