Dipyridamole inhibits human peritoneal mesothelial cell proliferation in vitro and attenuates rat peritoneal fibrosis in vivo

Enhancing PKA-dependent mesothelial barrier integrity reduces ovarian cancer transmesothelial migration via inhibition of contractility

Cancer-mesothelial cell interactions are critical for multiple solid tumors to colonize the surface of peritoneal organs. Understanding mechanisms of mesothelial barrier dysfunction that impair its protective function is critical for discovering mesothelial-targeted therapies to combat metastatic spread. Here, we utilized a live cell imaging-based assay to elucidate the dynamics of ovarian cancer spheroid transmesothelial migration and mesothelial-generated mechanical forces. Treatment of mesothelial cells with the adenylyl cyclase agonist forskolin strengthens cell-cell junctions, reduces actomyosin fibers, contractility-driven matrix displacements, and cancer spheroid transmigration in a protein kinase A (PKA)-dependent mechanism. We also show that inhibition of the cytoskeletal regulator Rho-associated kinase in mesothelial cells phenocopies the anti-metastatic effects of forskolin. Conversely, upregulation of contractility in mesothelial cells disrupts cell-cell junctions and increases the clearance rates of ovarian cancer spheroids. Our findings demonstrate the critical role of mesothelial cell contractility and mesothelial barrier integrity in regulating metastatic dissemination within the peritoneal microenvironment.

Development and Optimization of Dipyridamole- and Roflumilast-Loaded Nanoemulsion and Nanoemulgel for Enhanced Skin Permeation: Formulation, Characterization, and In Vitro Assessment

This study explores developing and optimizing a nanoemulsion (NE) system loaded with dipyridamole and roflumilast, aiming to improve skin penetration and retention. The NE formulation was further transformed into a nanoemulgel to enhance its application as a topical treatment for psoriasis. Solubility studies were conducted to select the oil, surfactant, and co-surfactant. Phase diagrams were constructed using the aqueous phase titration method. All the formulations were in nanoscale, and Formula (F2) (which contains oleic acid oil as the oil phase, a mixture of Surfactant Tween 80 and co-surfactant (ethanol) at a ratio of 1:2 in addition to distilled water as an aqueous phase in a ratio of 1:5:4, respectively) was the selected formula depending on the particle size, PDI, and zeta potential. Formula (F2) has the best ratio because it gives the smallest nanoemulsion globule size (particle size average of 167.1 nm), the best homogenicity (lowest PDI of 0.195), and the highest stability (higher zeta potential of -32.22). The selected formula was converted into a nanoemulgel by the addition of 0.5% (w/w) xanthan gum (average particle size of 172.7 nm) and the best homogenicity (lowest PDI of 0.121%) and highest stability (higher zeta potential of -28.31). In conclusion, the selected formula has accepted physical and chemical properties, which enhanced skin penetration.

Hub genes, diagnostic model, and predicted drugs in systemic sclerosis by integrated bioinformatics analysis

Background: Systemic sclerosis (scleroderma; SSc), a rare and heterogeneous connective tissue disease, remains unclear in terms of its underlying causative genes and effective therapeutic approaches. The purpose of the present study was to identify hub genes, diagnostic markers and explore potential small-molecule drugs of SSc. Methods: The cohorts of data used in this study were downloaded from the Gene Expression Complex (GEO) database. Integrated bioinformatic tools were utilized for exploration, including Weighted Gene Co-Expression Network Analysis (WGCNA), least absolute shrinkage and selection operator (LASSO) regression, gene set enrichment analysis (GSEA), Connectivity Map (CMap) analysis, molecular docking, and pharmacokinetic/toxicity properties exploration. Results: Seven hub genes (THY1, SULF1, PRSS23, COL5A2, NNMT, SLCO2B1, and TIMP1) were obtained in the merged gene expression profiles of GSE45485 and GSE76885. GSEA results have shown that they are associated with autoimmune diseases, microorganism infections, inflammatory related pathways, immune responses, and fibrosis process. Among them, THY1 and SULF1 were identified as diagnostic markers and validated in skin samples from GSE32413, GSE95065, GSE58095 and GSE125362. Finally, ten small-molecule drugs with potential therapeutic effects were identified, mainly including phosphodiesterase (PDE) inhibitors (BRL-50481, dipyridamole), TGF-β receptor inhibitor (SB-525334), and so on. Conclusion: This study provides new sights into a deeper understanding the molecular mechanisms in the pathogenesis of SSc. More importantly, the results may offer promising clues for further experimental studies and novel treatment strategies.

PPARγ alleviates peritoneal fibrosis progression along with promoting GLUT1 expression and suppressing peritoneal mesothelial cell proliferation

OBJECTIVE

Peritoneal fibrosis (PF) is commonly induced by bioincompatible dialysate exposure during peritoneal dialysis, but the underlying mechanisms remain elusive. This study aimed to investigate the roles of peroxisome proliferator-activated receptor gamma (PPARγ) in PF pathogenesis.

METHODS

Rat and cellular PF models were established by high glucose dialysate and lipopolysaccharide treatments. Serum creatinine, urea nitrogen, and glucose contents were detected by ELISA. Histological evaluation was done through H&E and Masson staining. GLUT1, PPARγ, and other protein expression were measured by qRT-PCR, western blotting, and IHC. PPARγ and GLUT1 subcellular distribution were detected using confocal microscopy. Cell proliferation was assessed by MTT and Edu staining.

RESULTS

Serum creatinine, urea nitrogen and glucose, and PPARγ and GLUT1 expression in rat PF model were reduced by PPARγ agonists Rosiglitazone or 15d-PGJ2 and elevated by antagonist GW9662. Rosiglitazone or 15d-PGJ2 repressed and GW9662 aggravated peritoneal fibrosis in rat PF model. PPARγ and GLUT1 were mainly localized in nucleus and cytosols of peritoneal mesothelial cells, respectively, which were reduced in cellular PF model, enhanced by Rosiglitazone or 15d-PGJ2, and repressed by GW9662. TGF-β and a-SMA expression was elevated in cellular PF model, which was inhibited by Rosiglitazone or 15d-PGJ2 and promoted by GW9662. PPARγ silencing reduced GLUT1, elevated a-SMA and TGF-b expression, and promoted peritoneal mesothelial cell proliferation, which were oppositely changed by PPARγ overexpression.

CONCLUSION

PPARγ inhibited high glucose-induced peritoneal fibrosis progression through elevating GLUT1 expression and repressing peritoneal mesothelial cell proliferation.

Potential Therapeutic Benefits of Dipyridamole in COVID-19 Patients

BACKGROUND

COVID-19 pandemic is caused by coronavirus also known as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). The viral infection continues to impact the globe with no vaccine to prevent the infection or highly effective therapeutics to treat the millions of infected people around the world. The disease starts as a respiratory infection, yet it may also be associated with a hypercoagulable state, severe inflammation owing to excessive cytokines production, and a potentially significant oxidative stress. The disease may progress to multiorgan failure and eventually death.

OBJECTIVE

In this article, we summarize the potential of dipyridamole as an adjunct therapy for COVID-19.

METHODS

We reviewed the literature describing the biological activities of dipyridamole in various settings of testing. Data were retrieved from PubMed, SciFinder-CAS, and Web of Science. The review concisely covered relevant studies starting from 1977.

RESULTS

Dipyridamole is an approved antiplatelet drug, that has been used to prevent stroke, among other indications. Besides its antithrombotic activity, the literature indicates that dipyridamole also promotes a host of other biological activities including antiviral, anti-inflammatory, and antioxidant ones.

CONCLUSION

Dipyridamole may substantially help improve the clinical outcomes of COVID-19 treatment. The pharmacokinetics profile of the drug is well established which makes it easier to design an appropriate therapeutic course. The drug is also generally safe, affordable, and available worldwide. Initial clinical trials have shown a substantial promise for dipyridamole in treating critically ill COVID-19 patients, yet larger randomized and controlled trials are needed to confirm this promise.

Reprogramming of Mesothelial-Mesenchymal Transition in Chronic Peritoneal Diseases by Estrogen Receptor Modulation and TGF-β1 Inhibition

In chronic peritoneal diseases, mesothelial-mesenchymal transition is determined by cues from the extracellular environment rather than just the cellular genome. The transformation of peritoneal mesothelial cells and other host cells into myofibroblasts is mediated by cell membrane receptors, Transforming Growth Factor β1 (TGF-β1), Src and Hypoxia-inducible factor (HIF). This article provides a narrative review of the reprogramming of mesothelial mesenchymal transition in chronic peritoneal diseases, drawing on the similarities in pathophysiology between encapsulating peritoneal sclerosis and peritoneal metastasis, with a particular focus on TGF-β1 signaling and estrogen receptor modulators. Estrogen receptors act at the cell membrane/cytosol as tyrosine kinases that can phosphorylate Src, in a similar way to other receptor tyrosine kinases; or can activate the estrogen response element via nuclear translocation. Tamoxifen can modulate estrogen membrane receptors, and has been shown to be a potent inhibitor of mesothelial-mesenchymal transition (MMT), peritoneal mesothelial cell migration, stromal fibrosis, and neoangiogenesis in the treatment of encapsulating peritoneal sclerosis, with a known side effect and safety profile. The ability of tamoxifen to inhibit the transduction pathways of TGF-β1 and HIF and achieve a quiescent peritoneal stroma makes it a potential candidate for use in cancer treatments. This is relevant to tumors that spread to the peritoneum, particularly those with mesenchymal phenotypes, such as colorectal CMS4 and MSS/EMT gastric cancers, and pancreatic cancer with its desmoplastic stroma. Morphological changes observed during mesothelial mesenchymal transition can be treated with estrogen receptor modulation and TGF-β1 inhibition, which may enable the regression of encapsulating peritoneal sclerosis and peritoneal metastasis.

The Effects of Irbesartan and Spironolactone in Prevention of Peritoneal Fibrosis in Rats

Background

Bacterial peritonitis episodes may disturb the functional and histological integrity of the peritoneum in peritoneal dialysis patients. The renin–angiotensin–aldosterone system may have fibrotic effects on the peritoneum.

Objective

To study the effects of an angiotensin II receptor antagonist (irbesartan) and an aldosterone antagonist (spironolactone) in the prevention of peritoneal fibrosis in a rat model of bacterial peritonitis.

Methods

40 Wistar rats were randomized into 5 groups: bacteria (B), bacteria–irbesartan (BI), bacteria–spironolactone (BS), bacteria–irbesartan–spironolactone (BIS), and control (C) groups. The C group received only dextran beads (Cytodex; Sigma Chemicals, St Louis, Missouri, USA); the others were given bacteria and dextran beads intraperitoneally. Irbesartan and/or spironolactone were given to 3 groups: BI, BS, and BIS. On the eighth day, the rats were sacrificed, peritoneal adhesion was quantified, and peritoneal tissue sections were evaluated histologically.

Results

The peritoneal total adhesion score was significantly higher in the B group than in the BI, BIS, and C groups ( p < 0.01). Mean peritoneal thickness, mean inflammation score, and mean fibrosis score were significantly higher in the B group in comparison to the C group ( p < 0.05). Mean peritoneal thickness of all treatment groups was significantly lower than the B group ( p < 0.05). Serum transforming growth factor beta-1 level was significantly higher in the B group than in the BI, BS, and C groups ( p < 0.05).

Conclusion

Irbesartan and spironolactone seem to decrease the extent of peritoneal injury caused by bacterial peritonitis.

Preserving the peritoneal membrane in long-term peritoneal dialysis patients

WHAT IS KNOWN AND OBJECTIVE

Peritoneal dialysis (PD) has been widely used by patients with end-stage renal disease. However, chronic exposure of the peritoneal membrane to bioincompatible PD solutions, and peritonitis and uraemia during long-term dialysis result in peritoneal membrane injury and thereby contribute to membrane changes, ultrafiltration (UF) failure, inadequate dialysis and technical failure. Therefore, preserving the peritoneal membrane is important to maintain the efficacy of PD. This article reviews the current literature on therapeutic agents for preserving the peritoneal membrane.

METHODS

A literature search of PubMed was conducted using the search terms peritoneal fibrosis, peritoneal sclerosis, membrane, integrity, preserve, therapy and peritoneal dialysis, but not including peritonitis. Published clinical trials, in vitro studies, experimental trials in animal models, meta-analyses and review articles were identified and reviewed for relevance.

RESULTS AND DISCUSSION

We focus on understanding how factors cause peritoneal membrane changes, the characteristics and mechanisms of peritoneal membrane changes in patients undergoing PD and the types of therapeutic agents for peritoneal membrane preservation. There have been many investigations into the preservation of the peritoneal membrane, including PD solution improvement, the inhibition of cytokine and growth factor expression using renin-angiotensin-aldosterone system (RAAS) blockade, glycosaminoglycans (GAGs), L-carnitine and taurine additives. In addition, there are potential future therapeutic agents that are still in experimental investigations.

WHAT IS NEW AND CONCLUSION

The efficacy of many of the therapeutic agents is uncertain because there are insufficient good-quality clinical studies. Overall membrane preservation and patient survival remain unproven in using more biocompatible PD solutions. With RAAS blockade, results are still inconclusive, as many of the clinical studies were retrospective. With GAGs, L-carnitine and taurine additives, there is no sufficiently long follow-up clinical study with a large sample size to support its efficacy. Therefore, better quality clinical studies within this area should be performed.

Genetic strain differences in the development of peritoneal fibroproliferative processes in mice

Fibroproliferative processes are regulated by a wide variety of tissue components and genetic factors. However, whether there are genetic differences in peritoneal fibroproliferative tissue formation, with consequent differences in response to drug treatment, is unclear. We characterize the influence of the genetic background on peritoneal fibroproliferative tissue induced by sponge implants in DBA/1, Swiss, C57BL/6, and BALB/c mouse strains. In addition, responses to dipyridamole in the implants were evaluated. Angiogenesis, assessed by intra-implant hemoglobin content, was highest in Swiss mice, whereas levels of vascular endothelial growth factor were highest in C57BL/6 mice. The levels of pro-inflammatory cytokines and of inflammatory enzymes (myeloperoxidase- and N-acetyl-β-D-glucosaminidase) were also strain-related. The pro-fibrogenic markers transforming growth factor beta-1 and collagen were lowest in implants placed in DBA/1 mice, whereas those in C57BL/6 mice had the highest levels. Differential sensitivity to dipyridamole was also observed, with this compound being pro-angiogenic in implants placed in DBA/1 mice but antiangiogenic in implants placed in Swiss. An overall anti-inflammatory response was observed in the inbred strains. Antifibrogenic effects were observed only in implants placed in C57BL/6 mice. These important strain-related differences in the development of peritoneal fibrosis and in response to dipyridamole must be considered in the design and analysis of studies on fibrogenesis in mice.

Genetic background determines inflammatory angiogenesis response to dipyridamole in mice

Inflammation and angiogenesis, key components of fibrovascular tissue growth, exhibit considerable variability among species and strains. We investigated whether the response of inbred and outbred mice strains to dipyridamole (DP) on these processes would present similar variability. The effects of the drug on blood vessel formation, inflammatory cell recruitment, collagen deposition and cytokine production were determined on the fibroproliferative tissue induced by sponge implants in Swiss and Balb/c mice. Angiogenesis as assessed by hemoglobin (Hb) and vascular endothelial growth factor (VEGF) concentrations differed between the strains. Swiss implants had the highest Hb content but the lowest VEGF concentrations. Systemic DP treatment exerted an antiangiogenic effect on Balb/c implants but an proangiogenic effect on Swiss implants. The inflammatory enzyme activities myeloperoxidase (six-fold higher in Balb/c implants) and N-acetyl- β-d-glucosaminidase were reduced by the treatment in Balb/c implants only. Nitrite concentrations were also higher in Balb/c implants by 40% after DP treatment. Tumor necrosis factor-alpha levels were similar in the implants of both strains and were not reduced by DP. Transforming growth factor β-1 levels and collagen deposition also varied between the strains. The inbred strain had similar levels of the cytokine but implants of Swiss mice presented more collagen. DP treatment reduced collagen deposition in Balb/c implants only. Our data showing the influence of the genetic background on marked heterogeneity of inflammatory angiogenesis components and differential sensitivity to DP may provide some answers to clinical evidence for resistance to angiogenic therapy.

Preservation of peritoneal morphology and function by pentoxifylline in a rat model of peritoneal dialysis: molecular studies

BACKGROUND

High-glucose (HG) content of dialysate accelerated peritoneal fibrosis. We investigated in vitro mechanisms and the in vivo potential of pentoxifylline (PTX) to prevent this fibrogenic process.

METHODS

For human peritoneal mesothelial cell (HPMC) culture, a normal-glucose (NG, 5.5 mM) or HG (138 mM) medium was established through pilot experiments. The rat peritoneal dialysis (PD) model consists of four groups (n = 8): group 1, intraperitoneal (IP) HG (4.25%) solution; group 2, as group 1 plus daily IP PTX (4 mg/in 1 h); group 3, IP PTX and group 4 as control.

RESULTS

In HPMC culture, PTX significantly prevented HG-stimulated gene and protein production of collagen and transforming growth factor-beta1 (TGF-ss1) (reduction rate of 72-81%). The p38 mitogen-activated protein kinase (MAPK) pathway was activated significantly in HG-treated HPMCs. Blockade of p38 MAPK by SB203580 (25 microM) or PTX (300 microg/ml) resulted in an effective suppression of collagen and TGF-ss1 gene expression in HG-cultured HPMCs. In PD experimental animals, peritoneal thickness and collagen expression in the peritoneum were significantly increased in HG-treated rats, and was attenuated by PTX (P < 0.01). Impaired peritoneal ultrafiltration (1.9 +/- 0.5 ml versus 2.4 +/- 0.4 ml, P < 0.05) and stimulated proinflammatory IL-6, MCP-1 and TGF-beta1 activation were observed in HG-treated rats. PTX well preserved the functional characteristics of peritoneum and cytokine profiles.

CONCLUSIONS

These in vitro and in vivo data suggest that PTX may have therapeutic benefits for the prevention or retardation of peritoneal fibrosis.

Peritoneal fibrosing syndrome: pathogenetic mechanism and current therapeutic strategies

Peritoneal dialysis (PD) has been established as a main renal replacement therapy for approximately 20 years. However, long-term peritoneal exposure to high glucose and other unphysiologic contents in the PD solution may potentiate the development of peritoneal fibrosing syndrome (PFS) in PD patients. PFS is composed of a wide spectrum of peritoneal alterations, which has been observed in PD patients. Molecular studies have shown that the fibrogenic effect of peritoneal mesothelial cells and the accompanying accumulation of extracellular matrix in the peritoneum are key events leading to PFS. In this review, we highlight the impact of PFS and its pathogenetic factors, including bioincompatible PD solution, multidisciplinary inflammatory mediators, and stimulatory cytokines in the peritoneal cavity. Current therapeutic strategies based on both clinical and basic evidence for the prevention or treatment of PFS are also reviewed.

Acute oxidative stress induces peritoneal hyperpermeability, mesothelial loss, and fibrosis

We explored the acute and long-term effects of short-lived, intense oxidative stress on peritoneal permeability and structure, induced with intraperitoneal injection of the oxidant agent deoxycholate, in rats. Ten minutes after the experimental intervention, peritoneal dialysis, performed over an exposure time of 60 minutes, revealed an increased urea dialysate/plasma ratio, greater glucose absorption, increased albumin losses in the effluent dialysate, and a reduced ultrafiltration rate. Mesothelial-cell imprints taken from the anterior liver surface indicated a substantially decreased density in the cell population. After the recovery period of 30 days, all alterations were still evident. Additionally, macroscopic and histologic observations made at this time interval detected peritoneal fibrosis and sclerosis, characterized by peritoneal adhesions, wrapping of intestinal loops, and the presence of a layer of fibrous tissue dressing the cavitary aspect of the liver peritoneal envelope. This report describes a reproducible experimental model of peritoneal fibrosis induced by acute oxidative injury. On the basis of these findings, it may be speculated that functional and structural alterations observed in patients are related to long-term continuous exposure of the monolayer to oxidative injury resulting from the high concentrations of d-glucose present in peritoneal dialysis solutions.

A(2B) adenosine receptors stimulate growth of porcine and rat arterial endothelial cells

The goal of this study was to determine which adenosine receptor subtype mediates growth stimulation by adenosine in arterial endothelial cells. In porcine coronary artery and rat aortic endothelial cells, 2-chloroadenosine (Cl-Ad), a metabolically stable analog of adenosine, stimulated DNA synthesis ((3)H-thymidine incorporation), cellular proliferation (cell number), collagen synthesis ((3)H-proline incorporation), and cell migration. The growth effects of adenosine and Cl-Ad were mimicked by the adenosine receptor agonist 5'-N-methylcarboxamidoadenosine but not by the adenosine receptor agonists N(6)-cyclopentyladenosine, 4-aminobenzyl-5'-N-methylcarboxamidoadenosine or CGS21680, an agonist profile consistent with an A(2B) receptor-mediated effect. The adenosine receptor antagonists KF17837 and 1,3-dipropyl-8-p-sulfophenylxanthine but not 8-cyclopentyl-1,3-dipropylxanthine blocked the growth-stimulatory effects of Cl-Ad and 5'-N-methylcarboxamidoadenosine, an antagonist profile consistent with an A(2) receptor-mediated action. Treatment of endothelial cells with erythro-9-(2-hydroxy-3-nonyl) adenine plus iodotubericidin (inhibitors of adenosine deaminase and adenosine kinase, respectively) induced endothelial cell growth, and these effects were blocked by 1,3-dipropyl-8-p-sulfophenylxanthine and KF17837 but not 8-cyclopentyl-1,3-dipropylxanthine, suggesting that endothelial cell-derived adenosine induces growth via A(2) receptors. The growth-stimulatory effects of Cl-Ad, 5'-N-methylcarboxamidoadenosine, and erythro-9-(2-hydroxy-3-nonyl) adenine plus iodotubericidin were abolished by antisense but not scrambled or sense oligonucleotides to the A(2B) receptor. Our findings strongly support the hypothesis that adenosine induces endothelial cell growth by activating A(2B) receptors. Thus, A(2B) receptors may play a critical role in regulating vascular remodeling associated with endothelial cell proliferation in angiogenesis, collateral vessel development, and recovery after vascular injury. Pharmacological or molecular biological activation of A(2B) receptors may be useful in modulating vascular remodeling.