Selective inhibition of phosphodiesterase-4 ameliorates chronic colitis and prevents intestinal fibrosis

The Complexity and Multiplicity of the Specific cAMP Phosphodiesterase Family: PDE4, Open New Adapted Therapeutic Approaches

Cyclic nucleotides (cAMP, cGMP) play a major role in normal and pathologic signaling. Beyond receptors, cyclic nucleotide phosphodiesterases; (PDEs) rapidly convert the cyclic nucleotide in its respective 5′-nucleotide to control intracellular cAMP and/or cGMP levels to maintain a normal physiological state. However, in many pathologies, dysregulations of various PDEs (PDE1-PDE11) contribute mainly to organs and tissue failures related to uncontrolled phosphorylation cascade. Among these, PDE4 represents the greatest family, since it is constituted by 4 genes with multiple variants differently distributed at tissue, cellular and subcellular levels, allowing different fine-tuned regulations. Since the 1980s, pharmaceutical companies have developed PDE4 inhibitors (PDE4-I) to overcome cardiovascular diseases. Since, they have encountered many undesired problems, (emesis), they focused their research on other PDEs. Today, increases in the knowledge of complex PDE4 regulations in various tissues and pathologies, and the evolution in drug design, resulted in a renewal of PDE4-I development. The present review describes the recent PDE4-I development targeting cardiovascular diseases, obesity, diabetes, ulcerative colitis, and Crohn’s disease, malignancies, fatty liver disease, osteoporosis, depression, as well as COVID-19. Today, the direct therapeutic approach of PDE4 is extended by developing allosteric inhibitors and protein/protein interactions allowing to act on the PDE interactome.

BI 1015550 is a PDE4B Inhibitor and a Clinical Drug Candidate for the Oral Treatment of Idiopathic Pulmonary Fibrosis

The anti-inflammatory and immunomodulatory abilities of oral selective phosphodiesterase 4 (PDE4) inhibitors enabled the approval of roflumilast and apremilast for use in chronic obstructive pulmonary disease and psoriasis/psoriatic arthritis, respectively. However, the antifibrotic potential of PDE4 inhibitors has not yet been explored clinically. BI 1015550 is a novel PDE4 inhibitor showing a preferential enzymatic inhibition of PDE4B. In vitro, BI 1015550 inhibits lipopolysaccharide (LPS)-induced tumor necrosis factor-α (TNF-α) and phytohemagglutinin-induced interleukin-2 synthesis in human peripheral blood mononuclear cells, as well as LPS-induced TNF-α synthesis in human and rat whole blood. In vivo, oral BI 1015550 shows potent anti-inflammatory activity in mice by inhibiting LPS-induced TNF-α synthesis ex vivo and in Suncus murinus by inhibiting neutrophil influx into bronchoalveolar lavage fluid stimulated by nebulized LPS. In Suncus murinus, PDE4 inhibitors induce emesis, a well-known gastrointestinal side effect limiting the use of PDE4 inhibitors in humans, and the therapeutic ratio of BI 1015550 appeared to be substantially improved compared with roflumilast. Oral BI 1015550 was also tested in two well-known mouse models of lung fibrosis (induced by either bleomycin or silica) under therapeutic conditions, and appeared to be effective by modulating various model-specific parameters. To better understand the antifibrotic potential of BI 1015550 in vivo, its direct effect on human fibroblasts from patients with idiopathic pulmonary fibrosis (IPF) was investigated in vitro. BI 1015550 inhibited transforming growth factor-β-stimulated myofibroblast transformation and the mRNA expression of various extracellular matrix proteins, as well as basic fibroblast growth factor plus interleukin-1β-induced cell proliferation. Nintedanib overall was unremarkable in these assays, but interestingly, the inhibition of proliferation was synergistic when it was combined with BI 1015550, leading to a roughly 10-fold shift of the concentration–response curve to the left. In summary, the unique preferential inhibition of PDE4B by BI 1015550 and its anticipated improved tolerability in humans, plus its anti-inflammatory and antifibrotic potential, suggest BI 1015550 to be a promising oral clinical candidate for the treatment of IPF and other fibro-proliferative diseases.

Therapeutic Targeting of Nrf2 Signaling by Maggot Extracts Ameliorates Inflammation-Associated Intestinal Fibrosis in Chronic DSS-Induced Colitis

Intestinal fibrosis is induced by excessive myofibroblast proliferation and collagen deposition, which has been regarded as a general pathological feature in inflammatory bowel disease (IBD). Therefore, identifying clinical markers and targets to treat and prevent intestinal fibrosis is urgently needed. The traditional Chinese medicine maggot, commonly known as “wu gu chong”, has been shown to reduce oxidative stress and alleviate inflammation in chronic colitis. This study investigated the mechanisms underlying the effects of maggot extract (ME) on inflammation-associated intestinal fibrosis in TGF-β1-stimulated human intestinal fibroblasts (CCD-18Co cells) and dextran sodium sulphate (DSS)-induced chronic colitis murine model. To assess the severity of inflammation and fibrosis, histological and macroscopic evaluation were carried out. The results showed that ME was a significant inhibitor of body weight loss and colon length shortening in mice with chronic colitis. In addition, ME suppressed the intestinal fibrosis by downregulating TGF-β1/SMADs pathway via upregulation of Nrf2 expression at both protein and mRNA levels. ME markedly increased the expression of Nrf2, thus resulting in a higher level of HO-1. After treatment with Nrf2 inhibitor (ML385) or siRNA-Nrf2 for deactivating Nrf2 pathway, the protective effects of ME were abolished both in vitro and in vivo. Moreover, the histopathological results for the major organs of DSS mice treated with ME showed no signs of clinically important abnormalities. Treatment with ME had no effect on the viability of CCD-18Co cells, suggesting its low in vitro cytotoxicity. Furthermore, ME could mediate intestine health by keeping the balance of the gut microbes through the enhancement of beneficial microbes and suppression of pathogenic microbes. In conclusion, this is the first ever report demonstrating that ME ameliorates inflammation-associated intestinal fibrosis by suppressing TGF-β1/SMAD pathway via upregulation of Nrf2 expression. Our findings highlight the potential of Nrf2 as an effective therapeutic target for alleviating intestinal fibrosis.

Apremilast Normalizes Gene Expression of Inflammatory Mediators in Human Keratinocytes and Reduces Antigen-Induced Atopic Dermatitis in Mice

Background

Apremilast, an oral phosphodiesterase (PDE) 4 inhibitor, has demonstrated efficacy in psoriasis, while its efficacy in atopic dermatitis (AD) was found to be modest. AD is a chronic inflammatory skin disease associated with activation of T helper (Th) 2 and Th17 immunity and a compromised epidermal barrier.

Objective

The objectives of this study were to examine the expression of PDE4 isoforms in skin from healthy subjects and AD patients, and to determine the effects of apremilast on AD-related inflammatory markers in vitro and in murine models of AD.

Methods

The expression of PDE4 isoforms (A, B, C, and D) in skin biopsies from healthy subjects and AD patients was evaluated using immunohistochemistry and digital image analysis. Using quantitative real-time reverse-transcriptase polymerase chain reaction, we evaluated the effects of apremilast on gene expression in adult human epidermal keratinocytes (HEKa) stimulated by Th2 and Th17 cytokines, and in two mouse models of antigen-induced AD.

Results

Expression of PDE4 isoforms increased up to three-fold in the epidermis of AD patients versus healthy skin. In interleukin (IL)-4 and IL-17-stimulated HEKa cells, apremilast significantly changed the expression of ILs, including IL-12/IL-23p40 and IL-31, and alarmins S100A7, S100A8, and S100A12. In mouse models of AD, apremilast significantly reduced ear swelling and monocyte chemoattractant protein-1 expression.

Conclusion

PDE4 is overexpressed in AD skin compared with normal skin, and inflammatory gene expression by human keratinocytes and mouse dermatitis can be modulated by apremilast.

Fibrostenotic strictures in Crohn's disease

The use of biologic agents including anti-tumor necrosis factor monoclonal antibodies followed by anti-integrins and anti-interleukins has drastically changed the treatment paradigm of Crohn’s disease (CD) by improving clinical symptoms and mucosal healing. However, up to 70% of CD patients still eventually undergo surgery mainly due to fibrostenotic strictures. There are no specific anti-fibrotic drugs yet. This review comprehensively addresses the mechanism, prediction, diagnosis and treatment of the fibrostenotic strictures in CD. We also introduce promising anti-fibrotic agents which may be available in the near future and summarize challenges in developing novel therapies to treat fibrostenotic strictures in CD.

TGF-β activity restoration and phosphodiesterase 4 inhibition as therapeutic options for inflammatory bowel diseases

In the last decades, the better understanding of inflammatory bowel diseases (IBD) pathogenesis has contributed to the identification of new therapeutic targets that can be modulated to induce and maintain disease remission. Monoclonal antibodies against tumor necrosis factor, interleukin (IL)-12/IL-23p40, and the integrin α4β7 and inhibitors of Janus kinase molecules are valid compounds to limit the function of molecules implicated in the control of IBD-related inflammation. However, not all patients respond to treatment with such drugs, some of them lose response over time and others develop serious side effects, such as infections or malignancies, which lead to the discontinuation of the therapy. Thus, an intensive research is ongoing with the goal to identify new targets and develop novel therapeutic options. In this context, restoration of TGF-β activity and inhibition of phosphodiesterase 4 (PD4) represent two relevant strategies. TGF-β is an immunesuppressive cytokine, whose activity is severely impaired in IBD due to the abundance of the intracellular inhibitor Smad7. Knockdown of Smad7 with a specific antisense oligonucleotide restores TGF-β signalling and dampens effector immune responses in pre-clinical studies and initial clinical trials in Crohn's disease patients, even though a recent phase 3 trial was discontinued due to an apparent inefficacy. PD4 inhibition determines the increase of intracellular levels of cyclic adenosine monophosphate, a mechanism that decreases pro-inflammatory cytokine production. A recent phase 2 study has shown that oral administration of PD4 associates with clinical benefit in patients with ulcerative colitis. In this article, we review the rationale and the available data relative to the use of these two agents in IBD.

Treatment with a Zinc Metalloprotease Purified from Bothrops moojeni Snake Venom (BmooMP-Alpha-I) Reduces the Inflammation in an Experimental Model of Dextran Sulfate Sodium-Induced Colitis

It has been described that the metalloprotease BmooMP-alpha-I purified from Bothrops moojeni snake venom is able to hydrolyze the TNF molecule. However, this observation has been based mainly on in vitro investigation, in addition to molecular modeling and docking approaches. Considering that there is no in vivo study to demonstrate the biological effects of this enzyme, the major aim to the present work was to investigate whether the BmooMP-alpha-I has any anti-inflammatory efficacy by setting up a murine experimental design of colitis induced by dextran sulfate sodium (DSS). For this purpose, C57BL/6 mice were divided into six groups, as follows: (i) animals without intestinal inflammation, (ii) animals without intestinal inflammation treated with BmooMP-alpha-I (50 μg/animal/day), and (iii) animals with intestinal inflammation induced by 3% of DSS, (iv) mice with intestinal inflammation induced by DSS and treated with BmooMP-alpha-I enzyme at the 50, 25, or 12.5 μg/animal/day dosages by intraperitoneal route. Clinical signs of colitis were observed daily for calculating the morbidity scores, cytokine measurements, and histological features. We observed that the animals treated with different doses of the enzyme presented a remarkable improvement of colitis signs, as confirmed by a significant increase of the intestine length in comparison to the DSS group. Also, no difference was observed between the groups treated with the enzyme or vehicle, as the colon length of these animals was slightly lower than that of the group of healthy animals, without induction of intestinal inflammation. The cytokine quantification in supernatants of intestinal tissue homogenates showed a significant reduction of 38% in IFN-gamma levels, when the animals were treated with 50 μg of the BmooMP-alpha-I compared to the animals receiving DSS only. A significant reduction of 39% in TNF levels was also observed in all doses of treatment with BmooMP-alpha-I, in addition to a significant reduction of 35% in the amount of IL-12p40. Histological examinations revealed that the BmooMP-alpha-I 50 μg treated group preserved colon architecture and goblet cells and reduced the ulcer area, when compared with DSS mice, which showed typical inflammatory changes in tissue architecture, such as ulceration, crypt dilation, loss of tissue architecture, and goblet cell depletion, accompanied by a significant cell infiltration. In conclusion, our results suggest that the improvement of clinical scores and histological findings related to BmooMP-alpha-I treatment in this experimental model could be attributed to the metalloprotease ability to modulate cytokine production locally at the inflamed intestine. These findings highlight the potential anti-inflammatory role and effectiveness of this enzyme as a therapeutic alternative in this type of immunopathological condition.

IL-17A Promotes Initiation and Development of Intestinal Fibrosis Through EMT

BACKGROUND

Intestinal fibrosis is a common complication of Crohn's disease (CD). Its exact mechanism is still unclear, and effective treatments to control or reverse the fibrosis process are unavailable. Epithelial-mesenchymal transition (EMT) may promote intestinal fibrosis by increasing deposition of extracellular matrix protein. IL-17A is a pro-inflammatory cytokine, and it has been shown as a profibrotic factor as its association with fibrosis of multiple organs was reported.

AIMS

To assess the roles of IL-17A and EMT in the initiation and development of intestinal fibrosis and to verify the potential inductive effect of IL-17A on EMT.

METHODS

In this study, we evaluated the expression of IL-17A and EMT-related genes in colonic mucosal biopsy tissues of CD patients and control individuals. Then, we examined the changes of EMT-related genes and fibrosis-related genes of IEC-6 cells which cultured for 72 h under increasing concentrations of IL-17A or with TGF-β1, to verify the potential inductive effect of IL-17A on EMT in vitro. We blocked the IL-17A of the mouse model of TNBS-induced experimental intestinal colitis and fibrosis to further verify the potential inductive effect of IL-17A on EMT in vivo.

RESULTS

We found the occurrence of EMT and high-level expression of IL-17A in intestinal mucosa of CD patients. Using IEC-6 cells, we showed that IL-17A may induce EMT in intestinal epithelial cells that come with reduced E-cadherin expression and increased expression of vimentin, snail, and α-SMA. We further found that anti-IL-17A treatment alleviated intestinal fibrosis through reducing EMT in mouse intestine.

CONCLUSIONS

Our study confirmed the involvement of IL-17A in the development of intestinal fibrosis through inducing EMT.

Phosphodiesterase-4 Inhibitors for the Treatment of Inflammatory Diseases

Phosphodiesterase-4 (PDE4), mainly present in immune cells, epithelial cells, and brain cells, manifests as an intracellular non-receptor enzyme that modulates inflammation and epithelial integrity. Inhibition of PDE4 is predicted to have diverse effects via the elevation of the level of cyclic adenosine monophosphate (cAMP) and the subsequent regulation of a wide array of genes and proteins. It has been identified that PDE4 is a promising therapeutic target for the treatment of diverse pulmonary, dermatological, and severe neurological diseases. Over the past decades, numerous PDE4 inhibitors have been designed and synthesized, among which roflumilast, apremilast, and crisaborole were approved for the treatment of inflammatory airway diseases, psoriatic arthritis, and atopic dermatitis, respectively. It is regrettable that the dramatic efficacies of a drug are often accompanied by adverse effects, such as nausea, emesis, and gastrointestinal reactions. However, substantial advances have been made to mitigate the adverse effects and obtain better benefit-to-risk ratio. This review highlights the dialectical role of PDE4 in drug discovery and the disquisitive details of certain PDE4 inhibitors to provide an overview of the topics that still need to be addressed in the future.

Parathyroid Hormone-Like Hormone Induces Epithelial-to-Mesenchymal Transition of Intestinal Epithelial Cells by Activating the Runt-Related Transcription Factor 2

Epithelial-to-mesenchymal transition (EMT) is a key contributor to fibroblast activation in fibrosis of multiple organs, including the intestine. Parathyroid hormone-like hormone (PTHLH) is an important factor in renal fibrosis and regulates several processes, including EMT. Herein, we investigated the role of PTHLH-induced EMT in intestinal fibrosis associated with Crohn disease. The expression levels of the EMT-related proteins, PTHLH, and parathyroid hormone receptor 1 (PTH1R) in intestinal tissues were determined by immunohistochemistry, and our results revealed that PTHLH and PTH1R were significantly elevated and associated with EMT marker expression. Moreover, neutralizing PTH1R and antagonizing PTHLH bioactivity prevented transforming growth factor-β1-induced EMT. PTH1R can propagate the protein kinase A (PKA) signal and activate downstream nuclear transcription factors, including runt-related transcription factor 2 (Runx2). In addition, lentiviral vector-PTHLH-treated mice were highly sensitive to 2,4,6-trinitrobenzene sulfonic acid, and analysis of the PTHLH-PTH1R axis revealed the involvement of PKA-Runx2 in PTHLH-induced EMT. Our results indicate that PTHLH triggered EMT in intestinal epithelial cells through the PKA-Runx2 pathway, which might serve as a therapeutic target for intestinal fibrosis in Crohn disease.

NF-E2-Related Factor 2 Suppresses Intestinal Fibrosis by Inhibiting Reactive Oxygen Species-Dependent TGF-β1/SMADs Pathway

BACKGROUND AND AIMS

This study aimed to evaluate the antifibrotic effects of NF-E2-Related Factor 2 (Nrf2) on intestinal fibrosis. Intestinal fibrosis is a common complication of Crohn's disease; however, its mechanism of intestinal fibrosis is largely unclear.

METHODS

BALB/c mice received 2,4,6-trinitrobenzene sulfonic acid weekly via intrarectal injections to induce chronic fibrotic colitis. They also diet containing received 1% (w/w) tert-butylhydroquinone (tBHQ), which is an agonist of Nrf2. Human intestinal fibroblasts (CCD-18Co cells) were pretreated with tBHQ or si-Nrf2 followed by stimulation with transforming growth factor-β1 (TGF-β1), which transformed the cells into myofibroblasts. The main fibrosis markers such as α-smooth muscle actin, collagen I, tissue inhibitor of metalloproteinase-1, and TGF-β1/SMADs signaling pathway were detected by quantitative real-time RT-PCR, immunohistochemical analysis, and Western blot analysis. Levels of cellular reactive oxygen species (ROS) were detected by dichlorodihydrofluorescein diacetate.

RESULTS

tBHQ suppressed the intestinal fibrosis through the TGF-β1/SMADs signaling pathway in TNBS-induced colitis and CCD-18Co cells. Moreover, Nrf2 knockdown enhanced the TGF-β1-induced differentiation of CCD-18Co cells. ROS significantly increased in TGF-β1-stimulated CCD-18Co cells. Pretreatment with H₂O₂, the primary component of ROS, was demonstrated to block the effect of tBHQ on reducing the expression of TGF-β1. Moreover, scavenging ROS by N-acetyl cysteine could inhibit the increasing expression of TGF-β1 promoted by Nrf2 knockdown.

CONCLUSIONS

The results suggested that Nrf2 suppressed intestinal fibrosis by inhibiting ROS/TGF-β1/SMADs pathway in vivo and in vitro.

PDE4 Inhibition and Inflammatory Bowel Disease: A Novel Therapeutic Avenue

BACKGROUND

In the last few decades, a better knowledge of the inflammatory pathways involved in the pathogenesis of Inflammatory Bowel Disease (IBD) has promoted biological therapy as an important tool to treat IBD patients. However, in spite of a wider spectrum of biological drugs, a significant proportion of patients is unaffected by or lose their response to these compounds, along with increased risks of infections and malignancies. For these reasons there is an urgent need to look for new pharmacological targets. The novel Phosphodiesterase 4 (PDE4) inhibitors have been recently introduced as new modulators of intracellular signals and gene transcription for the treatment of IBD.

AIM

To discuss and describe the state of the art of this new class of compounds in the IBD field, with particular attention to apremilast.

METHODS

Published articles selected from PubMed were comprehensively reviewed, with key words including apremilast, inflammatory disease, IBD, psoriasis, psoriatic arthritis, pathogenesis, therapies, and treatment.

RESULTS

PDE4 inhibitors generate elevated intracellular levels of cyclic Adenosine Monophosphate (cAMP), that consequently down-regulate the release of pro-inflammatory cytokines in the mucosa of IBD patients. The newly developed apremilast is one of these drugs and has already been approved for the treatment of dermatologic/rheumatologic inflammatory conditions; studies in psoriasis and psoriatic arthritis have in fact demonstrated its clinical activity. However, no clinical trials have yet been published on the use of apremilast in IBD.

CONCLUSION

In light of the similarity of pro-inflammatory signaling pathways across the gut, the skin, and joints, apremilast is likely supposed to show its efficacy also in IBD.

Curcumin Suppresses Intestinal Fibrosis by Inhibition of PPARγ-Mediated Epithelial-Mesenchymal Transition

Intestinal fibrotic stricture is a major complication of Crohn's disease (CD) and epithelial-to-mesenchymal transition (EMT) is considered as an important contributor to the formation of intestinal fibrosis by increasing extracellular matrix (ECM) proteins. Curcumin, a compound derived from rhizomes of Curcuma, has been demonstrated with a potent antifibrotic effect. However, its effect on intestinal fibrosis and the potential mechanism is not completely understood. Here we found that curcumin pretreatment significantly represses TGF-β1-induced Smad pathway and decreases its downstream α-smooth muscle actin (α-SMA) gene expression in intestinal epithelial cells (IEC-6); in contrast, curcumin increases expression of E-cadherin and peroxisome proliferator-activated receptor γ (PPARγ) in IEC-6. Moreover, curcumin promotes nuclear translocation of PPARγ and the inhibitory effect of curcumin on EMT could be reversed by PPARγ antagonist GW9662. Consistently, in the rat model of intestinal fibrosis induced by 2,4,5-trinitrobenzene sulphonic acid (TNBS), oral curcumin attenuates intestinal fibrosis by increasing the expression of PPARγ and E-cadherin and decreasing the expression of α-SMA, FN, and CTGF in colon tissue. Collectively, these results indicated that curcumin is able to prevent EMT progress in intestinal fibrosis by PPARγ-mediated repression of TGF-β1/Smad pathway.

A novel model for studying ileitis-induced visceral hypersensitivity in goats

BACKGROUND

Visceral hypersensitivity (VH) is a common condition in many gastrointestinal disorders such as inflammatory bowel diseases (IBDs) in human and animals. Most studies often induce Crohn's disease/colitis to investigate VH in small experimental animals. Although farm animals commonly suffer from IBDs, their VH has not been investigated so far. Because goats can suffer from Johne's disease, a naturally occurring Crohn's-like disease, they may be suitable to be used for studying the mechanism underlying VH in common intestinal disorders of large animals. In the present study, 60 healthy goats of either sex were equally divided into a 2, 4, 6-trinitrobenzenesulfonic acid (TNBS) group and saline group. A volume of 1.2 ml of TNBS-ethanol solution (30 mg TNBS in 40 % ethanol) or an equal volume of isotonic saline was injected into the wall of the terminal ileum through laparotomy. The severity of the developing ileitis was determined according to macro- and microscopic pathologic scores and the levels of myeloperoxidase, interleukin-1β, interleukin-6 and tumor necrosis factor-α, and VH was evaluated with visceromotor responses (VMR) to colorectal distension on days 3, 7, 14, 21 and 28. VMRs were assessed with a continuous ramp distention mode with 6 s for each pressure (20, 40, 60, 80 and 100 mmHg).

RESULTS

Compared to the saline group, the TNBS-treated goats showed apparent transmural pathological changes and a significant increase (P < 0.05) in macroscopic and microscopic change scores, and levels of myeloperoxidase, interleukin-1β, interleukin-6 and tumor necrosis factor-α in the ileum, and VMR to colorectal distension. The goats exhibited apparent ileitis at days 3 to 21, and VH at days 7 to 28 following TNBS treatment.

CONCLUSION

This experiment successfully established a reproducible ileitis and VH with administration of TNBS-ethanol solution in the ileal wall of goats. This model is useful for studying the pathogenesis of the IBD and the mechanism underlying VH, and for evaluating the efficacy of new therapeutic regimens.

Phosphodiesterase 4 in inflammatory diseases: Effects of apremilast in psoriatic blood and in dermal myofibroblasts through the PDE4/CD271 complex

Phosphodiesterases 4 (PDE4) act as proinflammatory enzymes via degradation of cAMP, whereas PDE4 inhibitors play an anti-inflammatory role in vitro and in vivo. In particular, apremilast has been recently approved for the treatment of psoriasis and psoriatic arthritis. However, little is known on the expression pattern of PDE4 in psoriasis. We report that PDE4B and PDE4D mRNA are overexpressed in peripheral blood mononuclear cells (PBMC) from psoriasis, as compared with normal controls, while apremilast reduces PBMC production of a number of pro-inflammatory cytokines and increases the levels of anti-inflammatory mediators. PDE4 expression is up-regulated in psoriatic dermis as compared with normal skin, with particular regard to fibroblasts. This is confirmed in vitro, where both dermal fibroblasts (DF) and, to a greater extent, myofibroblasts (DM) express all PDE4 isoforms at the mRNA and protein level. Because PDE4 interacts with the nerve growth factor (NGF) receptor CD271 in lung fibroblasts, we evaluated the relationship and function of PDE4 and CD271 in normal human skin fibroblasts. All PDE4 isoforms co-immunoprecipitate with CD271 in DM, while apremilast inhibits apoptosis induced by β-amyloid, a CD271 ligand, in DM. Furthermore, apremilast significantly reduces NGF- and transforming growth factor-β1 (TGF-β1)-induced fibroblast migration, and inhibits DF differentiation into DM mediated by NGF or TGF-β1. Finally, in DM, apremilast significantly reduces cAMP degradation induced by treatment with β-amyloid. Taken together, these results indicate that PDE4 play an important role in psoriasis. In addition, the study reveals that the PDE4/CD271 complex could be important in modulating fibroblast functions.

Homocysteine promotes intestinal fibrosis in rats with trinitrobenzene sulfonic acid-induced colitis

BACKGROUND AND AIM

Previous studies have revealed significantly increased levels of plasma and mucosal homocysteine (Hcy) in patients with Crohn's disease (CD); however, whether Hcy is involved in intestinal fibrosis of CD remains unclear. This study aimed to investigate the effects of Hcy on intestinal fibrosis in TNBS/ethanol-induced colitis and to elucidate its potential mechanisms.

METHODS

Sprague-Dawley rats were divided into 4 groups: normal control, normal + Hcy injection, TNBS model and TNBS model + Hcy injection. Hyperhomocysteinemia was induced by subcutaneous injection of Hcy. DAI, CMDI and HI were calculated to evaluate the severity of colitis. Masson trichrome staining was performed to assess the severity of fibrosis. The plasma and mucosal levels of Hcy were measured by HPLC-FD. The levels of IL-1β, IL-6, TNF-α, TGF-β1, CTGF, MMP-2,9 and collagen I, III in the colon were determined by ELISA, and the mRNA expressions of TGF-β1, MMP-2,9 and TIMP-1 were detected by RT-PCR.

RESULTS

Hcy was found to increase the scores of DAI, CMDI and HI; levels of IL-1β, Il-6, TNF-α, TGF-β1, CTGF, MMP-2,9 and collagen I, III; and mRNA expressions of TGF-β1, MMP-2,9 and TIMP-1 in colonic tissue of rats with TNBS/ethanol-induced colitis.

CONCLUSIONS

Hcy promotes intestinal fibrosis in rats with TNBS/ethanol-induced colitis, the underlying mechanisms of which may be attributed to its effects of increasing inflammatory damage, promoting the expression of profibrogenic cytokines and influencing MMPs/TIMPs balance.

Effect of homocysteine on intestinal permeability in rats with experimental colitis, and its mechanism

OBJECTIVE

To investigate the effect of homocysteine (Hcy) on intestinal permeability in rats with TNBS/ethanol-induced colitis and elucidate its mechanism.

METHODS

Sprague-Dawley rats were divided into four groups: normal, normal + Hcy injection, TNBS model, and TNBS model + Hcy injection. Experimental colitis was induced by trinitrobenzene sulfonic acid (TNBS) in 50% ethanol; rats were injected subcutaneously with Hcy from the first day after the induction of experimental colitis on 30 consecutive days. To determine the severity of colitis, the disease activity index (DAI) was evaluated; colon tissues were collected for the detection of the activity of myeloperoxidase (MPO) and the contents of MDA, IL-1β, IL-6, TNF-α, MMP-2, and MMP-9. Intestinal epithelial permeability was assessed with Evans blue (EB) dye. The levels of Hcy in plasma and colon mucosa were measured by high-performance liquid chromatography-fluorescence detection (HPLC-FD).

RESULTS

Compared with the normal group, the DAI scoring and MPO activity, contents of MDA, IL-1β, IL-6, TNF-α, MMP-2, MMP-9 in the colon and EB in the small intestine were significantly increased in the TNBS group (P < 0.01). Compared with the TNBS model group, the DAI scoring, plasma and colonic mucosa Hcy levels, MPO activity and contents of MDA, IL-1β, IL-6, TNF-α, MMP-2, MMP-9 in colon and EB in small intestine were significantly increased in the TNBS-induced colitis rats with simultaneous Hcy injection (P < 0.01).

CONCLUSION

Hcy can increase intestinal permeability and aggravate inflammatory damage in rats with TNBS-induced colitis, the underlying mechanisms of which may be attributed to its effects of promoting the expression of MMP-2 and MMP-9, leading to injury of the intestinal barrier.

Cyclic AMP regulates the migration and invasion potential of human pancreatic cancer cells

Aggressive dissemination and metastasis of pancreatic ductal adenocarcinoma (PDAC) results in poor prognosis and marked lethality. Rho monomeric G protein levels are increased in pancreatic cancer tissue. As the mechanisms underlying PDAC malignancy are little understood, we investigated the role for cAMP in regulating monomeric G protein regulated invasion and migration of pancreatic cancer cells. Treatment of PDAC cells with cAMP elevating agents that activate adenylyl cyclases, forskolin, protein kinase A (PKA), 6-Bnz-cAMP, or the cyclic nucleotide phosphodiesterase inhibitor cilostamide significantly decreased migration and Matrigel invasion of PDAC cell lines. Inhibition was dose-dependent and not significantly different between forskolin or cilostamide treatment. cAMP elevating drugs not only blocked basal migration, but similarly abrogated transforming-growth factor-β-directed PDAC cell migration and invasion. The inhibitory effects of cAMP were prevented by the pharmacological blockade of PKA. Drugs that increase cellular cAMP levels decreased levels of active RhoA or RhoC, with a concomitant increase in phosphorylated RhoA. Diminished Rho signaling was correlated with the appearance of thickened cortical actin bands along the perimeter of non-motile forskolin or cilostamide-treated cells. Decreased migration did not reflect alterations in cell growth or programmed cell death. Collectively these data support the notion that increased levels of cAMP specifically hinder PDAC cell motility through F-actin remodeling.

Rolipram attenuates bile duct ligation-induced liver injury in rats: a potential pathogenic role of PDE4

Anti-inflammatory and antifibrotic effects of the broad spectrum phosphodiesterase (PDE) inhibitor pentoxifylline have suggested an important role for cyclic nucleotides in the pathogenesis of hepatic fibrosis; however, studies examining the role of specific PDEs are lacking. Endotoxemia and Toll-like receptor 4 (TLR4)-mediated inflammatory and profibrotic signaling play a major role in the development of hepatic fibrosis. Because cAMP-specific PDE4 critically regulates lipopolysaccharide (LPS)-TLR4-induced inflammatory cytokine expression, its pathogenic role in bile duct ligation-induced hepatic injury and fibrogenesis in Sprague-Dawley rats was examined. Initiation of cholestatic liver injury and fibrosis was accompanied by a significant induction of PDE4A, B, and D expression and activity. Treatment with the PDE4-specific inhibitor rolipram significantly decreased liver PDE4 activity, hepatic inflammatory and profibrotic cytokine expression, injury, and fibrosis. At the cellular level, in relevance to endotoxemia and inflammatory cytokine production, PDE4B was observed to play a major regulatory role in the LPS-inducible tumor necrosis factor (TNF) production by isolated Kupffer cells. Moreover, PDE4 expression was also involved in the in vitro activation and transdifferentiation of isolated hepatic stellate cells (HSCs). Particularly, PDE4A, B, and D upregulation preceded induction of the HSC activation marker α-smooth muscle actin (α-SMA). In vitro treatment of HSCs with rolipram effectively attenuated α-SMA, collagen expression, and accompanying morphologic changes. Overall, these data strongly suggest that upregulation of PDE4 expression during cholestatic liver injury plays a potential pathogenic role in the development of inflammation, injury, and fibrosis.

The selective phosphodiesterase 4 inhibitor roflumilast and phosphodiesterase 3/4 inhibitor pumafentrine reduce clinical score and TNF expression in experimental colitis in mice

OBJECTIVE

The specific inhibition of phosphodiesterase (PDE)4 and dual inhibition of PDE3 and PDE4 has been shown to decrease inflammation by suppression of pro-inflammatory cytokine synthesis. We examined the effect of roflumilast, a selective PDE4 inhibitor marketed for severe COPD, and the investigational compound pumafentrine, a dual PDE3/PDE4 inhibitor, in the preventive dextran sodium sulfate (DSS)-induced colitis model.

METHODS

The clinical score, colon length, histologic score and colon cytokine production from mice with DSS-induced colitis (3.5% DSS in drinking water for 11 days) receiving either roflumilast (1 or 5 mg/kg body weight/d p.o.) or pumafentrine (1.5 or 5 mg/kg/d p.o.) were determined and compared to vehicle treated control mice. In the pumafentrine-treated animals, splenocytes were analyzed for interferon-γ (IFNγ) production and CD69 expression.

RESULTS

Roflumilast treatment resulted in dose-dependent improvements of clinical score (weight loss, stool consistency and bleeding), colon length, and local tumor necrosis factor-α (TNFα) production in the colonic tissue. These findings, however, were not associated with an improvement of the histologic score. Administration of pumafentrine at 5 mg/kg/d alleviated the clinical score, the colon length shortening, and local TNFα production. In vitro stimulated splenocytes after in vivo treatment with pumafentrine showed a significantly lower state of activation and production of IFNγ compared to no treatment in vivo.

CONCLUSIONS

These series of experiments document the ameliorating effect of roflumilast and pumafentrine on the clinical score and TNF expression of experimental colitis in mice.

Emodin reduces intestinal fibrosis in rats with TNBS-induced colitis

AIM: To investigate the anti-fibrotic effects of emodin in rats with experimental colitis, and to explore the possible mechanisms.

METHODS: Rats with colitis induced with trinitrobenzene sulphonic acid (TNBS) were used as the model of intestinal fibrosis. Thirty-four rats were randomly divided into normal group, model group and emodin group. Colitis was induced with TNBS in rats of the model group and emodin group. Rats in the emodin group were gavaged with 40 mg/kg of emodin daily, and the other groups were gavaged with an equal volume of 0.9% NaCl solution. Body weight loss and changes in stool and activities were observed, and DAI was calculated. At the end of the experiment, colon tissue samples were collected, and the general and histological scores were given. The injury and fibrosis of the colon were detected by HE staining and Masson collagen staining, respectively. Expression of transforming growth factor (TGF)-β1, collagenⅠ, collagen Ⅲ, Smad3 and α-SMA was determined by FQ-PCR.

RESULTS: Compared to the model group, the general condition, general and histological scores, and fibrosis were improved significantly in the emodin group. Expression of TGF-β1, collagenⅠ, collagen Ⅲ, Smad3 and α-SMA in colonic mucosa in the emodin group were significantly lower than that in the model group (1.27 ± 0.78 vs 4.56 ± 3.14; 0.60 ± 0.59 vs 2.15 ± 1.22; 0.92 ± 1.38 vs 3.34 ± 1.47; 3.11 ± 2.81 vs 8.77 ± 6.40; 0.87 ± 0.62 vs 2.40 ± 1.15, all P < 0.05), while expression of E-cad was higher in the emodin group (1.01 ± 0.34 vs 0.30 ± 0.23, P < 0.05).

CONCLUSION: Emodin reduces intestinal fibrosis in rats with TNBS-induced colitis possibly by down-regulation of TGF-β1/Smad3 signaling and inhibition of epithelial-mesenchymal transition.

Dynamic progress of 2,4,6-trinitrobenzene sulfonic acid induced chronic colitis and fibrosis in rat model

OBJECTIVE

To investigate the dynamic progress of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced chronic colitis and fibrosis in rat model.

METHODS

In all, 44 Sprague-Dawley rats were randomly divided into the model and control groups. Colitis was induced by intrarectal injection of 10-30 mg TNBS in 50% ethanol enema weekly for 5 cycles. The control group received an equal volume of 50% ethanol. If the rat died during the procedure, necropsy was performed immediately. At the end of the 2nd, 3rd, 4th and 5th week the rats were sacrificed, and histological damage and fibrosis of the colon were examined using HE and Masson trichrome stain. The concentrations of Th1, Th2, Th17 cytokines in colon tissue were detected by ELISA, intestinal fibrosis-relevant cytokine expressions were detected by fluorescent quantification-polymerase chain reaction.

RESULTS

Colitis model was successfully induced with a low mortality rate. The microscopic colonic damage score, collagen area, Th1/Th17 cytokines and expressions of intestinal fibrosis-relevant cytokines were significantly higher in the model group than those in the control group. Furthermore, the collagen area, content of interleukin 17 and expressions of intestinal fibrosis-related cytokines in the model group were more elevated in the chronic phase (after 3 to 4 cycles) than in the acute phase (P < 0.05).

CONCLUSIONS

Multiple inflammatory responses participate in the formation and dynamic progression of TNBS-induced chronic colitis. In particular, acute colitis may turn into chronic colitis after 3 cycles of TNBS administration. This coincides with the formation of intestinal fibrosis which is concomitantly exacerbated after cycle 4.

Cyclic AMP dysregulates intestinal epithelial cell restitution through PKA and RhoA

BACKGROUND

Mucosal homeostasis is dependent on the establishment and maintenance of the cell-cell contacts that comprise the physiological barrier. Breaks in the barrier are linked to multiple diseases such as inflammatory bowel disease. While increased cyclic adenosine monophosphate (cAMP) levels limit inflammation by decreasing leukocyte infiltration, the effects of elevated cAMP on intestinal epithelial repair are unknown.

METHODS

Restitution in animals administered rolipram was monitored by microscopic examination after laser wounding of the intestinal epithelium or in mice treated with dextran sodium sulfate (DSS). In vitro analysis was conducted using IEC6 and T84 cells to determine the role of elevated cAMP in altering Rho-dependent cellular migration signaling pathways.

RESULTS

We show that treatment with rolipram, forskolin, and cAMP analogs decrease intestinal epithelial cell migration in vitro. In vivo cell imaging revealed that increased cAMP resulted in a decreased cellular migration rate, with cells at the edge displaying the highest activity. As expected, elevated cAMP elicited increased protein kinase A (PKA) activity, in turn resulting in the inactivation and sequestration of RhoA and decreased actin reorganization. The ablation of restitution by cAMP was not restricted to cell culture, as forskolin and rolipram treatment significantly decreased epithelial microwound closure induced by the two photon confocal injury model.

CONCLUSIONS

Together, these data suggest that administration of cAMP-elevating agents paradoxically decrease infiltration of damage-causing leukocytes while also preventing epithelial repair and barrier maintenance. We propose that treatment with cAMP-elevating agents severely limits mucosal reepithelialization and should be contraindicated for use in chronic inflammatory bowel disorders.

Apremilast mechanism of action and application to psoriasis and psoriatic arthritis

Psoriasis and psoriatic arthritis are common clinical conditions that negatively impact health-related quality of life and are linked to serious medical comorbidities. Disease mechanisms involve local and systemic chronic inflammatory processes. Available biologic therapies specifically target single inflammatory mediators, such as tumor necrosis factor-α (TNF-α), in the context of a larger inflammatory signaling cascade. To interrupt this pathological cascade earlier in the response or further upstream, and return pro-inflammatory and anti-inflammatory signaling to a homeostatic balance, the use of a phosphodiesterase4 (PDE4) inhibitor has been explored. PDE4 is the major enzyme class responsible for the hydrolysis of cyclic adenosine monophosphate (cAMP), an intracellular second messenger that controls a network of pro-inflammatory and anti-inflammatory mediators. With PDE4 inhibition, and the resulting increases in cAMP levels in immune and non-immune cell types, expression of a network of pro-inflammatory and anti-inflammatory mediators can be modulated. Apremilast is an orally available targeted PDE4 inhibitor that modulates a wide array of inflammatory mediators involved in psoriasis and psoriatic arthritis, including decreases in the expression of inducible nitric oxide synthase, TNF-α, and interleukin (IL)-23 and increases IL-10. In phase II studies of subjects with psoriasis and psoriatic arthritis, apremilast reversed features of the inflammatory pathophysiology in skin and joints and significantly reduces clinical symptoms. The use of an oral targeted PDE4 inhibitor for chronic inflammatory diseases, like psoriasis and psoriatic arthritis, represents a novel treatment approach that does not target any single mediator, but rather focuses on restoring a balance of pro-inflammatory and anti-inflammatory signals.

Transforming growth factor-beta type 1 receptor (ALK5) and Smad proteins mediate TIMP-1 and collagen synthesis in experimental intestinal fibrosis

Transforming growth factor β (TGF-β) is known to play a key role in intestinal fibrosis; however, the underlying mechanisms are not well understood. TGF-β signal transduction is through TGF-β receptors, including the TGF-β type 1 receptor. Most cell types contain a TGF-β type 1 receptor form known as activin receptor-like kinase 5 (ALK5), which propagates the signal to the nucleus through the phosphorylation of Smad2 and Smad3 proteins. Therefore, we assessed the effect of the disruption of TGF-β/ALK5/Smad signalling by an ALK5 inhibitor (SD-208) in two experimental animal models of intestinal fibrosis: anaerobic bacteria- and trinitrobenzensulphonic acid-induced colitis. In addition, isolated myofibroblasts were pretreated with SD-208 and exposed to recombinant TGF-β1. Finally, myofibroblasts were transfected with ALK5, Smad2, and Smad3-specific siRNA. Up-regulation of ALK5 and TIMP-1, phosphorylation of Smad2 and Smad3 proteins, and increased intestinal wall collagen deposition were found in both experimental animal models. These effects were decreased by SD-208. TGF-β1 treatment also induced phosphorylation of Smad2 and Smad3 and up-regulation of ALK5 protein, TIMP-1, and α2 type 1 collagen gene expression in isolated myofibroblasts. Again these effects were inhibited by SD-208. Also, ALK5, Smad2, and Smad3 siRNA abolished the induction of TIMP-1 and α2 type 1 collagen. Our findings provide evidence that the TGF-β/ALK5/Smad pathway participates in the pathogenesis of experimental intestinal fibrosis. These data show promise for the development of an effective therapeutic intervention in this condition.

Effects of phosphodiesterase 4 inhibition on bleomycin-induced pulmonary fibrosis in mice

Background

Pulmonary fibrosis (PF) is a group of devastating and largely irreversible diseases. Phosphodiesterase (PDE) 4 is involved in the processes of remodeling and inflammation, which play key role in tissue fibrosis. The aim of the study was, therefore, to investigate the effect of PDE4 inhibition in experimental model of PF.

Methods

PF was induced in C57BL/6N mice by instillation of bleomycin. Pharmacological inhibition of PDE4 was achieved by using cilomilast, a selective PDE4 inhibitor. Changes in either lung inflammation or remodeling were evaluated at different stages of experimental PF. Lung inflammation was assessed by bronchoalveolar lavage fluid (BALF) differential cell count and reverse transcription quantitative polymerase chain reaction (RT-qPCR) for inflammatory cytokines. Changes in tissue remodeling were evaluated by pulmonary compliance measurement, quantified pathological examination, measurement of collagen deposition and RT-qPCR for late remodeling markers. Survival in all groups was analyzed as well.

Results

PDE4 inhibition significantly reduced the total number of alveolar inflammatory cells in BALF of mice with bleomycin-induced PF at early fibrosis stage (days 4 and 7). Number of macrophages and lymphocytes, but not neutrophils, was significantly reduced as well. Treatment decreased lung tumor necrosis factor (TNF)-α mRNA level and increased mRNA level of interleukin (IL)-6 but did not influence IL-1β. At later stage (days 14 and 24) cilomilast improved lung function, which was shown by increase in lung compliance. It also lowered fibrosis degree, as was shown by quantified pathological examination of Hematoxilin-Eosin stained lung sections. Cilomilast had no significant effect on the expression of late remodeling markers such as transforming growth factor (TGF)-β1 and collagen type Ia1 (COL(I)α1). However, it tended to restore the level of lung collagen, assessed by SIRCOL assay and Masson's trichrome staining, and to improve the overall survival.

Conclusions

Selective PDE4 inhibition suppresses early inflammatory stage and attenuates the late stage of experimental pulmonary fibrosis.

Apremilast, a cAMP phosphodiesterase-4 inhibitor, demonstrates anti-inflammatory activity in vitro and in a model of psoriasis

BACKGROUND AND PURPOSE

Apremilast is an orally administered phosphodiesterase-4 inhibitor, currently in phase 2 clinical studies of psoriasis and other chronic inflammatory diseases. The inhibitory effects of apremilast on pro-inflammatory responses of human primary peripheral blood mononuclear cells (PBMC), polymorphonuclear cells, natural killer (NK) cells and epidermal keratinocytes were explored in vitro, and in a preclinical model of psoriasis.

EXPERIMENTAL APPROACH

Apremilast was tested in vitro against endotoxin- and superantigen-stimulated PBMC, bacterial peptide and zymosan-stimulated polymorphonuclear cells, immunonoglobulin and cytokine-stimulated NK cells, and ultraviolet B light-activated keratinocytes. Apremilast was orally administered to beige-severe combined immunodeficient mice, xenotransplanted with normal human skin and triggered with human psoriatic NK cells. Epidermal skin thickness, proliferation index and inflammation markers were analysed.

KEY RESULTS

Apremilast inhibited PBMC production of the chemokines CXCL9 and CXCL10, cytokines interferon-gamma and tumour necrosis factor (TNF)-alpha, and interleukins (IL)-2, IL-12 and IL-23. Production of TNF-alpha by NK cells and keratinocytes was also inhibited. In vivo, apremilast significantly reduced epidermal thickness and proliferation, decreased the general histopathological appearance of psoriasiform features and reduced expression of TNF-alpha, human leukocyte antigen-DR and intercellular adhesion molecule-1 in the lesioned skin.

CONCLUSIONS AND IMPLICATIONS

Apremilast displayed a broad pattern of anti-inflammatory activity in a variety of cell types and decreased the incidence and severity of a psoriasiform response in vivo. Inhibition of TNF-alpha, IL-12 and IL-23 production, as well as NK and keratinocyte responses by this phosphodiesterase-4 inhibitor suggests a novel approach to the treatment of psoriasis.

CC-10004 but not thalidomide or lenalidomide inhibits lamina propria mononuclear cell TNF-α and MMP-3 production in patients with inflammatory bowel disease

BACKGROUND

Thalidomide, one of whose activities is to inhibit Tumour Necrosis Factor (TNF)-α production, has been reported to be an effective treatment for refractory inflammatory bowel disease (IBD). TNF-α driven production of matrix metalloproteinase (MMP)-3 by gut lamina propria mononuclear cells (LPMCs) is a major pathway of tissue injury in IBD; however the effect of thalidomide and newer more potent immunomodulatory derivatives on this pathway has not been studied.

AIM

To investigate the effect of thalidomide, CC-4047 (pomalidomide), CC-5013 (lenalidomide), and CC-10004 (apremilast) on gut LPMC TNFα and MMP-3 production in patients with IBD.

METHODS

Gut LPMCs and myofibroblasts were isolated from patients with IBD, and cultured with thalidomide, CC-4047, CC-5013, and CC-10004. MMP-3 and TIMP-1 levels were determined by western blotting and real-time PCR, and TNF-α levels by ELISA.

RESULTS

CC-10004 significantly reduced both TNF-α production and MMP-3 production by cultured LPMCs. Thalidomide and CC-4047 and CC-5013 had no significant effect on the production of TNF-α or MMP-3 by LPMCs.

CONCLUSION

These results provides a mechanistic rationale for both the failure of lenalidomide (CC-5013) in a recent randomised controlled trial in Crohn's disease, and for the evaluation of CC-10004 as a novel oral therapy in the treatment of CD and UC.

The effect of sildenafil, a phosphodiesterase-5 inhibitor, on acetic acid-induced colonic inflammation in the rat

BACKGROUND AND AIM

Sildenafil, a selective and potent inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase (PDE)5, has a relaxant effect on the smooth muscle cells of the arterioles supplying the human corpus cavernosum acting via nitric oxide (NO)-dependent mechanism. This study aimed to investigate the possible protective effect of sildenafil citrate on the extent of tissue integrity, oxidant-antioxidant status and neutrophil infiltration to the inflamed organ in a rat model of acetic acid-induced colitis.

METHODS

Colitis was induced by intrarectal administration of 1 mL of 5% acetic acid to Sprague-Dawley rats (200-250 g; n = 7-8/group). Control rats received an equal volume of saline intrarectally. In treatment groups, the rats were treated with either sildenafil citrate (5 mg/kg/day; subcutaneously) or saline for 3 days. After decapitation, distal colon was weighed and scored macroscopically and microscopically. Tissue samples were used for the measurement of malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO) activity, and oxidant production. Trunk blood was collected for the assessment of serum tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta levels.

RESULTS

In the colitis group, the colonic tissue was characterized by lesions, increased lipid peroxidation with a concomitant reduction in GSH content, increased MPO activity and oxidant production. Serum TNF-alpha and IL-1beta levels were higher in the colitis group compared to control values. Sildenafil reversed these inflammatory parameters nearly back to control values.

CONCLUSIONS

Sildenafil citrate administration to rats with acetic acid-induced colitis seems to be beneficial via prevention of lipid peroxidation, oxidant generation, cytokine production and neutrophil accumulation.

Tetomilast suppressed production of proinflammatory cytokines from human monocytes and ameliorated chronic colitis in IL-10-deficient mice

BACKGROUND

Tetomilast (OPC-6535) was originally developed as a compound inhibiting superoxide production in neutrophils. Although its mechanism of action is not completely understood, phosphodiesterase type 4 inhibitory function has been postulated. The therapeutic effect of PDE4 inhibitors has been reported for chronic inflammatory disorders such as chronic obstructive pulmonary diseases. In this study we aimed to examine whether tetomilast could be a novel drug for inflammatory bowel diseases by further clarifying its antiinflammatory effects.

METHODS

Cytokines from human peripheral blood mononuclear cells were measured by enzyme-linked immunosorbent assay (ELISA) and Cytokine Beads Array. The transcripts were quantified by reverse-transcriptase polymerase chain reaction (RT-PCR). Phosphorylation of transcription factors was examined by phosflow. To examine its in vivo effect, a once-daily oral dose of tetomilast was tested in murine IL-10(-/-) chronic colitis.

RESULTS

Tetomilast suppressed TNF-alpha and IL-12 but not IL-10 production from lipopolysaccharide (LPS)-stimulated human monocytes. It suppressed TNF-alpha, IFN-gamma, and IL-10 from CD4 lymphocytes. Tetomilast suppressed cytokine production at the transcriptional level but did not alter phosphorylation of p65, ERK, p38, and STAT3. HT-89, a protein kinase A inhibitor, did not abolish the effect of tetomilast, suggesting that it was independent from the classical cAMP/PKA pathway. IL-10 was not essential to the inhibitory effect of tetomilast on TNF-alpha and IL-12. Tetomilast ameliorated IL-10(-/-) chronic colitis with reduced clinical symptoms, serum amyloid A, and histological scores with decreased TNF-alpha mRNA expression.

CONCLUSIONS

Tetomilast exerts its antiinflammatory effects on human monocytes and CD4 cells. Combined with in vivo data these findings support the feasibility of tetomilast as a novel drug for inflammatory bowel diseases.

Prevention of colonic fibrosis by Boswellia and Scutellaria extracts in rats with colitis induced by 2,4,5-trinitrobenzene sulphonic acid

BACKGROUND

Currently, no effective preventive measures or medical therapies are available for intestinal fibrosis and, thus, surgery remains the only available strategy in the management of fibrostenotic enteropathies, especially Crohn's disease. The aim of this study was to evaluate the efficacy of a combined therapy of anti-inflammatory Boswellia and antifibrotic Scutellaria extracts on the development of colonic fibrosis in rats.

MATERIALS AND METHODS

Chronic colonic inflammation-associated fibrosis was induced in rats by intracolonic administration of 2,4,5-trinitrobenzene sulphonic acid (TNBS). Sixty-four healthy male Sprague-Dawley rats were assigned to five groups: 8 controls, 14 TNBS, 14 TNBS orally treated with Boswellia extracts (50 mg kg(-1) day(-1)), 14 TNBS orally treated with Scutellaria extracts (150 mg kg(-1) day(-1)), and 14 TNBS orally treated with both Boswellia (50 mg kg(-1) day(-1)) and Scutellaria extracts (150 mg kg(-1) day(-1)). The colon was removed after 21 days of treatment and assessed by macroscopic, histological, morphometric and immunohistochemical analyses. For immunohistochemical analysis, alpha-smooth muscle actin (alpha-SMA), collagen types I-III, connective tissue growth factor (CTGF), transforming growth factor-beta1 (TGF-beta1), Smad3, Smad7 and CD3 antibodies were used.

RESULTS

Combined oral administration of Boswellia and Scutellaria significantly improved the course and macroscopic findings of TNBS-induced chronic colitis assessed by disease activity index, colon weight, length, adhesions, strictures, dilatation, thickness, oedema, ulcerations and extension of damage. The histological severity of the colonic fibrosis was also notably improved by the treatment and associated with a significant reduction in the colonic expression of alpha-SMA, collagen I-III, CTGF, TGF-beta1, Smad3, and Smad7.

CONCLUSIONS

These data demonstrate that the prophylactic administration of anti-inflammatory Boswellia and antifibrotic Scutellaria extracts is effective in preventing colonic fibrosis in TNBS-induced colitis. Their antifibrotic mechanism of action seems to be mediated by the inhibition of TGF-beta1/Smad3 pathway.

Inhibition of Phosphodiesterase Type 4 Decreases Stress-Induced Defecation in Rats and Mice

BACKGROUND/AIMS

Phosphodiesterase type 4 (PDE4) has been previously shown to regulate colonic contractile activity in vitro. In this study, the effects of PDE4 inhibition were assessed in a model of stress-induced defecation previously demonstrated to be due to increased colonic transit/evacuation.

METHODS

Rats were individually placed in a mild restraint cage and placed into a 12 degrees C environment (cold-restraint stress) for 60 min. Mice received restraint (only) stress at room temperature for 30 min. Loperamide (positive control compound) or two different PDE4 inhibitors (rolipram and roflumilast) were administered orally at several doses to the rodents 1 h before stress began. Vehicle alone was administered for comparison. The number of fecal pellets expelled during stress (fecal pellet output), total fecal pellet wet weight and total fecal water content were measured.

RESULTS

Loperamide produced a dose-related decrease (ID(50)s in mg/kg) in fecal pellet output (rat = 7.4, mouse = 0.7) and significantly decreased fecal wet weight (72.9%) and decreased fecal percent water content (9.4%). The two PDE4 inhibitors produced a similar dose-related inhibition of fecal pellet output. Rolipram exhibited ID(50)s in rat and mouse of 14.1 and 27.1, respectively. Rolipram significantly decreased fecal wet weight (58.8%) but increased fecal percent water content (15.0%). For roflumilast, ID(50)s were 24.2 mg/kg and 12.4 in the rat and mouse, respectively. Although roflumilast also significantly (p < 0.05) decreased fecal wet weight (47.2%), it did not significantly increase fecal percent water content.

CONCLUSIONS

These data indicate that PDE4 inhibition is effective in reducing rodent stress-induced defecation, provides the first functional data on a potential role for PDE4 activity in the colonic evacuation response to stress, and indicates the potential utility of PDE4 inhibitors in functional bowel disease such as irritable bowel syndrome requires further evaluation.

Treatment of Peyronie's disease with oral pentoxifylline

BACKGROUND

A 51-year-old male presented with a penile deformity without obvious etiology. Physical examination revealed hard plaques in the dorsal and ventral penis.

INVESTIGATIONS

Physical examination, penile ultrasound.

DIAGNOSIS

Peyronie's disease.

MANAGEMENT

Oral pentoxifylline.