Krishnendu Ganguly

Matrix metalloproteinase‐9 activity and expression is reduced by melatonin during prevention of ethanol‐induced gastric ulcer in mice

Abstract:  Matrix metalloproteinases (MMPs) play an important role in degradation of gastric extracellular matrix proteins. However, no reports are available on the relationship between the activity of MMPs and gastric ulceration induced by alcohol. Our objective was to investigate the effect of melatonin (N‐acetyl‐5‐methoxytryptamine) on the regulation of MMP‐9 and MMP‐2 activities during prevention of ethanol‐induced gastric ulcer. Biochemical and zymographic methods were used to analyze MMP‐9 and ‐2 activities in gastric tissues of Balb/c mice following induction of gastric ulcer by ethanol. Our studies reveal that melatonin arrested cell injury, protein carbonyl formation, and lipid peroxidation in mice during gastroprotection. Melatonin dose‐dependently reduced proMMP‐9 activity that was induced (∼ 25‐fold) during ethanol‐induced gastric ulceration. Severity of gastric ulcers were correlated proportionately with increased dose of ethanol and elevated activity of proMMP‐9 and ‐2. The reduced activities of MMP‐9 and ‐2 were associated with reduced expression of TNF‐α and increased expression of tissue inhibitors of metalloproteinases (TIMP‐1 and TIMP‐2). We conclude that melatonins ability to prevent ethanol‐induced gastric ulceration in mice is related to a reduction in proMMP‐9 activity and expression.

Melatonin promotes angiogenesis during protection and healing of indomethacin-induced gastric ulcer: role of matrix metaloproteinase-2.

Abstract:  Matrix metalloproteinase (MMP)‐2 is considered as a crucial regulator of angiogenesis, a process of new blood vessel formation. We reported previously that melatonin (N‐acetyl‐5‐methoxy tryptamine), an antioxidant and anti‐inflammatory agent, prevents indomethacin‐induced gastric ulcers. Herein, we investigated the effect of melatonin on MMP‐2‐mediated angiogenesis during gastroprotection. Angiogenic properties of melatonin were tested in both rat corneal micropocket assay and in mouse model of indomethacin‐induced gastric lesions. Melatonin augmented angiogenesis that was associated with amelioration of MMP‐2 expression and activity and, upregulation of vascular endothelial growth factor (VEGF) in rat cornea. Melatonin prevented gastric lesions by promoting angiogenesis via upregulation of VEGF followed by over‐expression of MMP‐2. Similarly, healing of gastric lesions was associated with early expression of VEGF followed by MMP‐2. In addition, upregulation of MMP‐2 was parallel to MMP‐14 and inverse to tissue inhibitor of metalloprotease (TIMP)‐2 expression during gastroprotection. Our data demonstrated that melatonin exerts angiogenesis through MMP‐2 and VEGF over‐expression during protection and healing of gastric ulcers. This study highlights for the first time a phase‐associated regulation of MMP‐2 activity in gastric mucosa and an angiogenic action of melatonin to rescue indomethacin‐induced gastropathy.

Effect of melatonin on secreted and induced matrix metalloproteinase‐9 and ‐2 activity during prevention of indomethacin‐induced gastric ulcer

Abstract:  Matrix metalloproteinases (MMPs) maintain the crucial role in physiological turnover of extracellular matrix (ECM) proteins in gastric tissues. However, a little is known about the relationship of MMPs with ECM degradation during gastric ulceration and ECM remodeling during healing. Our objective was to investigate the effect of melatonin (N‐acetyl‐5 methoxytryptamine) on the regulation of MMP‐9 and MMP‐2 activity during prevention of gastric ulcer. In the present study, biochemical and zymographic methods were used to analyze the mechanism of melatonin in indomethacin‐induced gastric ulcer in a rat model. Our studies reveal that melatonin dose‐dependently downregulates the expression and secretion of pro‐MMP‐9 which is induced (approximately 10‐fold) during indomethacin‐induced gastric ulceration. Furthermore, melatonin prevents gastric ulceration in a dose‐dependent manner through upregulation (approximately two‐ to threefold) of both pro‐MMP‐2 and active MMP‐2 at the level of induction as well as secretion. It also prevents gastric ulcers by blocking glutathione depletion and lipid peroxidation in cytosolic and microsomal fractions. The novel findings of this study are attributed to the attenuation of the pro‐MMP‐9 and increase of MMP‐2 activity by pretreatment with melatonin. The finding defines one of the MMP‐mediated pathways for melatonins action in gastric ulcer.

Matrix Metalloproteinase (MMP) 9 Transcription in Mouse Brain Induced by Fear Learning

Background: Matrix metalloproteinase 9 is involved in fear-associated memory formation wherein transcriptional regulation is poorly known. Results: Overexpression and promoter binding activity of AP-1 factors regulate MMP-9 transcription, preceding elevated enzymatic activity in mouse brain. Conclusion: c-Fos and c-Jun AP-1 components positively regulate MMP-9 transcription in fear learning. Significance: The novel tools and approaches in vivo allowed us to explore MMP-9 transcription in mouse brain. Memory formation requires learning-based molecular and structural changes in neurons, whereas matrix metalloproteinase (MMP) 9 is involved in the synaptic plasticity by cleaving extracellular matrix proteins and, thus, is associated with learning processes in the mammalian brain. Because the mechanisms of MMP-9 transcription in the brain are poorly understood, this study aimed to elucidate regulation of MMP-9 gene expression in the mouse brain after fear learning. We show here that contextual fear conditioning markedly increases MMP-9 transcription, followed by enhanced enzymatic levels in the three major brain structures implicated in fear learning, i.e. the amygdala, hippocampus, and prefrontal cortex. To reveal the role of AP-1 transcription factor in MMP-9 gene expression, we have used reporter gene constructs with specifically mutated AP-1 gene promoter sites. The constructs were introduced into the medial prefrontal cortex of neonatal mouse pups by electroporation, and the regulation of MMP-9 transcription was studied after contextual fear conditioning in the adult animals. Specifically, −42/-50- and −478/-486-bp AP-1 binding motifs of the mouse MMP-9 promoter sequence have been found to play a major role in MMP-9 gene activation. Furthermore, increases in MMP-9 gene promoter binding by the AP-1 transcription factor proteins c-Fos and c-Jun have been demonstrated in all three brain structures under investigation. Hence, our results suggest that AP-1 acts as a positive regulator of MMP-9 transcription in the brain following fear learning.

Induction of matrix metalloproteinase-9 and -3 in nonsteroidal anti-inflammatory drug-induced acute gastric ulcers in mice: regulation by melatonin.

Abstract:  The pathogenesis of gastric ulcer is associated with remodeling of extracellular matrix (ECM) by various matrix metalloproteinases (MMPs). However, how MMPs are regulated during nonsteroidal anti‐inflammatory drug (NSAID)‐induced acute gastric ulceration is not well studied. In this study, different NSAIDs (80 mg/kg b.w.) were applied to generate acute gastric ulcer in the BALB/c mouse and the regulation of MMPs were investigated. NSAIDs caused dose‐dependent induction in MMP‐9 and ‐3 activities and expressions in ulcerated gastric tissues along with significant infiltration of inflammatory cells and disruption of gastric mucosal layer. In addition, an increase in tumor necrosis factor (TNF)‐α, interleukin (IL)‐1β and IL‐8 expression, excessive generation of hydroxyl radical (•OH), and protein oxidation and lipid peroxidation were observed in acute ulcerated gastric tissues. In this study, the efficacy of melatonin on activities of MMP‐9 and ‐3 during prevention of gastric ulcers was tested. Melatonin at a dose of 60 mg/kg b.w. downregulated MMP‐9 and ‐3 both at the enzyme and protein levels in mouse gastric tissues during prevention as well as healing of acute gastric ulcers. It also blocked oxidative stress via inhibition of protein oxidation, lipid peroxidation, •OH generation and SOD‐2 expression. Moreover, it suppressed myeloperoxidase activity and expressions of TNF‐α, IL‐1β and IL‐8. This study documents for the first time that induction of MMP‐9 and ‐3 activities accompany NSAID‐induced inflammation and oxidative stress in gastric tissues and indicates that, melatonin may be a preventive or therapeutic remedy for gastric ulcers.

Chronic gastric ulceration causes matrix metalloproteinases-9 and -3 augmentation: Alleviation by melatonin

Matrix metalloproteinases (MMPs) are a family of zinc-dependent enzymes capable of degradation of extracellular matrix (ECM) and key player in various inflammatory diseases. We investigated the regulation of MMPs in chronic gastric ulceration in mice. We generated chronic gastric ulcers in mice by indomethacin and examined the activity and expression of MMP-9 and -3 in stomach. Melatonin (N-acetyl-5-methoxytryptamine) treatment has also been applied to mice to characterize the changes in expression and activities of MMPs in gastric tissues. We observed significant upregulation of MMP-9 and -3 expressions and activities in stomach with increasing doses and duration of indomethacin that corroborated with increased activity of activator protein (AP)-1. Substantial damage in gastric epithelial layer was found during chronic ulceration. Melatonin suppressed MMP-9 and -3 expressions and activities during prevention and healing of chronic gastric ulcers. It also suppressed protein oxidation, lipid peroxidation and antioxidant enzymes. Additionally, expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-8 was significantly high in ulcerated stomachs while melatonin treatment blocked them to control level. We found elevated phosphorylation of extracellular-regulated kinase (ERK)1/2 and c-Jun N-terminal kinase (JNK) during chronic gastric ulceration, which were significantly reversed by melatonin. Moreover, expression of NF-κB, c-fos and c-jun were inhibited by melatonin resulting down regulation of MMP-9 and -3 expressions. In summary, oxidative stress is preceded by chronic inflammation that enhances the expression of MMP-9 and -3, while melatonin arrests both of them via reduction of AP-1 activity during protection of ulcer.

Curcumin Heals Indomethacin-Induced Gastric Ulceration by Stimulation of Angiogenesis and Restitution of Collagen Fibers via VEGF and MMP-2 Mediated Signaling

AIM We examined the molecular mechanism of curcumin in a preventive and therapeutic model of indomethacin-induced gastric ulceration with regard to angiogenic processes. RESULTS Disrupted blood vessels, reduced collagen matrices, and significant (60%) injury to mucosal cells were observed during ulceration. In addition, ulcerated tissues exhibited decreased matrix metalloproteinase (MMP)-2 and vascular endothelial growth factor (VEGF) expression in blood vessels. Interestingly, curcumin blocked ulceration by induction of collagenization and angiogenesis in gastric tissues via upregulation of MMP-2, membrane type (MT) 1-MMP, VEGF, and transforming growth factor (TGF)-β at protein and messenger ribonucleic acid (mRNA) levels. To examine the angiogenic properties of curcumin, we employed a chorioallantoic membrane model and Matrigel assay. During healing, curcumin promoted collagenization and angiogenesis as well as enhanced MMP-2 activity via positive MT1-MMP regulation and negative tissue inhibitor of metalloproteinase-2 regulation. INNOVATION Our study demonstrates that curcumin-mediated healing is associated with increased MMP-2, TGF-β, and VEGF expression and that it plays a pivotal role as an angiogenic modulator by stimulating vascular sprout formation and collagen fiber restoration in ulcerated tissues. CONCLUSION We conclude that curcumin remodels gastric tissues by restoring the collagen architecture and accelerating angiogenesis.