The many faces of EMMPRIN - roles in neuroinflammation

Biological marker for the establishment of periodontal disease: cross-sectional study in the gingival tissue

BACKGROUND

The present study investigated the expression of COX-2, EMMPRIN, HIF-1α, and GLUT-1 in the gingival tissue to verify if there is a correlation between the immunoexpression of these proteins and the changes caused by the inflamed infiltrate present in the gingival tissues.

MATERIAL AND METHODS

A morphological analysis of epithelial changes (hyperplasia, exocytosis, spongiosis, and hydropic degeneration) was performed, as well as a semiquantitative analysis of the immunoexpression of COX-2, EMMPRIN, HIF-1α, and GLUT-1 in the epithelium and connective tissue of 60 specimens of gingival tissue.

RESULTS

Epithelial immunoexpression to COX-2 was observed in three cases, while EMMPRIN, HIF-1α, and GLUT-1 were strongly expressed in the basal layer of the epithelium and gradually decreased until the upper layers. In the connective tissue, COX-2 immunoexpression showed a statistically significant association (p < 0.001) with the gingival inflammatory infiltrate. In connective tissue, EMMPRIN and HIF-1α exhibited intense immunopositivity, while GLUT-1 was negative in most cases.

CONCLUSION

COX-2 expression may constitute a biological marker of gingival tissues since its epithelial immunoexpression may indicate a greater propensity for the establishment of periodontal disease.

The renoprotective effects of taurine against diabetic nephropathy via the p38 MAPK and TGF-β/Smad2/3 signaling pathways

Diabetic nephropathy (DN), a severe diabetes complication, causes kidney morphological and structural changes due to extracellular matrix accumulation. This accumulation is caused mainly by oxidative stress. Semi-essential amino acid derivative taurine has powerful antioxidant and antifibrotic effects. The aim of this study was to investigate the renoprotective effects of taurine through its possible roles in oxidative stress, extracellular matrix proteins, and the signaling pathways associated with the accumulation of extracellular matrix proteins in DN rats. 29 Wistar albino rats were randomly separated into control, taurine, diabetes, and diabetes + taurine groups. Diabetes animals were injected 45 mg/kg streptozosine. Taurine is given by adding to drinking water as 1% (w/v). Urine, serum, and kidney tissue were collected from rats for biochemical and histological analysis after 12 weeks. According to the studies, taurine significantly reduces the levels of malondialdehyde (MDA), total oxidant status (TOS), and protein expression of NADPH oxidase 4 (NOX4) that increase in diabetic kidney tissue. Also, decreased superoxide dismutase (SOD) activity levels significantly increased with taurine in diabetic rats. Moreover, increased mRNA and protein levels of fibronectin decreased with taurine. The matrix metalloproteinase (MMP)-2 and MMP-9 activities and their mRNA levels increased significantly, and this increase was significantly summed with taurine. There was a decrease in mRNA expression of Extracellular matrix metalloproteinase inducer (EMMPRIN). Taurine significantly increased this decrease. Diabetes increased mRNA expressions of transforming growth factor (TGF)-β and Smad2/3. Taurine significantly reduced this induction. TGF-β protein expression, p38, and Smad2/3 activations were also inhibited, but taurine was suppressed significantly. All these findings indicate that taurine may be an effective practical strategy to prevent renal diabetic injury.

Importance of lactate dehydrogenase (LDH) and monocarboxylate transporters (MCTs) in cancer cells

Background

In most regions, cancer ranks the second most frequent cause of death following cardiovascular disorders.

Aim

In this article, we review the various aspects of glycolysis with a focus on types of MCTs and the importance of lactate in cancer cells.

Results and Discussion

Metabolic changes are one of the first and most important alterations in cancer cells. Cancer cells use different pathways to survive, energy generation, growth, and proliferation compared to normal cells. The increase in glycolysis, which produces substances such as lactate and pyruvate, has an important role in metastases and invasion of cancer cells. Two important cellular proteins that play a role in the production and transport of lactate include lactate dehydrogenase and monocarboxylate transporters (MCTs). These molecules by their various isoforms and different tissue distribution help to escape the immune system and expansion of cancer cells under different conditions.

Factors Associated with RANTES, EMMPIRIN, MMP2 and MMP9, and the Association of These Biomarkers with Cardiovascular Disease in a Multi-Ethnic Population

BACKGROUND

The growing cardiovascular disease (CVD) epidemic calls for further research to identify novel biomarkers for earlier detection and as potential therapeutic targets. Biomarkers Regulated on Activation, Normal T Cell Expressed and Secreted (RANTES), extracellular matrix metalloproteinase inducer (EMMPRIN), and matrix metalloproteinases (MMP-2, and MMP-9) are linked to proatherogenic and proinflammatory pathways of CVD development, the majority of which are coronary artery disease (CAD) and stroke. We evaluated potential factors affecting these four biomarkers and established their association with CVD.

METHODS

This is a cross-sectional analysis using a nested case-control design involving 580 participants aged 21-75 years from the prospective multi-ethnic cohort study. A total of 290 CVD cases and 290 age-and sex-matched controls were identified. All participants underwent interviews, health screenings, and provided blood samples, including biomarkers RANTES, EMMPRIN, and MMPs. CVD was defined based on previous medical history.

RESULTS

The average age of the participants was 55.7(SD = 10.3) years of age, and 34.6% were female. Arrhythmia history and low-density lipoprotein (LDL) levels were significant factors of logEMMPRIN (β = -0.124 [-0.245, -0.003] and β = 0.111 [0.0, 0.191], respectively). Only female sex (β = 0.189 [0.078, 0.300]) for logRANTES and age (β = 0.033 [0.010, 0.055]) for logMMP-2 and logMMP-9 were significant. The Indian ethnicity (β = 0.192 [0.048, 0.335]) and highly sensitive C-reactive protein (hs-CRP) levels (β = 0.063 [0.011, 0.116]) were statistically significant for logMMP-9. No association was detected between biomarkers and CVD.

CONCLUSIONS

In this multi-ethnic study cohort, RANTES was associated with sex, EMMPRIN was associated with a history of arrhythmia and LDL levels, MMP-2 with age, and MMP-9 with ethnicity and hs-CRP levels. The biomarker serum levels were not associated with CVD.

Extracellular matrix metalloproteinase inducer in brain ischemia and intracerebral hemorrhage

Increasing evidence from preclinical and clinical studies link neuroinflammation to secondary brain injury after stroke, which includes brain ischemia and intracerebral hemorrhage (ICH). Extracellular matrix metalloproteinase inducer (EMMPRIN), a cell surface transmembrane protein, is a key factor in neuroinflammation. It is widely elevated in several cell types after stroke. The increased EMMPRIN appears to regulate the expression of matrix metalloproteinases (MMPs) and exacerbate the pathology of stroke-induced blood-brain barrier dysfunction, microvascular thrombosis and neuroinflammation. In light of the neurological effects of EMMPRIN, we present in this review the complex network of roles that EMMPRIN has in brain ischemia and ICH. We first introduce the structural features and biological roles of EMMPRIN, followed by a description of the increased expression of EMMPRIN in brain ischemia and ICH. Next, we discuss the pathophysiological roles of EMMPRIN in brain ischemia and ICH. In addition, we summarize several important treatments for stroke that target the EMMPRIN signaling pathway. Finally, we suggest that EMMPRIN may have prospects as a biomarker of stroke injury. Overall, this review collates experimental and clinical evidence of the role of EMMPRIN in stroke and provides insights into its pathological mechanisms.

Neuroprotective Effects of Chlorogenic Acid in a Mouse Model of Intracerebral Hemorrhage Associated with Reduced Extracellular Matrix Metalloproteinase Inducer

Chlorogenic acid (CGA) has been reported to have various biological activities, such as anti-inflammatory, anti-oxidant and anti-apoptosis effects. However, the role of CGA in intracerebral hemorrhage (ICH) and the underlying mechanisms remain undiscovered. The current study aims to investigate the effect of CGA on neuroinflammation and neuronal apoptosis after inhibition of EMMPRIN in a collagenase-induced ICH mouse model. Dose optimization data showed that intraperitoneal administration of CGA (30 mg/kg) significantly attenuated neurological impairments and reduced brain water content at 24 h and 72 h compared with ICH mice given vehicle. Western blot and immunofluorescence analyses revealed that CGA remarkably decreased the expression of extracellular matrix metalloproteinase inducer (EMMPRIN) in perihematomal areas at 72 h after ICH. CGA also reduced the expression of matrix metalloproteinases-2/9 (MMP-2/9) at 72 h after ICH. CGA diminished Evans blue dye extravasation and reduced the loss of zonula occludens-1 (ZO-1) and occludin. CGA-treated mice had fewer activated Iba-1-positive microglia and MPO-positive neutrophils. Finally, CGA suppressed cell death around the hematoma and reduced overall brain injury. These outcomes highlight that CGA treatment confers neuroprotection in ICH likely by inhibiting expression of EMMPRIN and MMP-2/9, and alleviating neuroinflammation, blood–brain barrier (BBB) disruption, cell death and brain injury.

EMMPRIN Promotes the Expression of MMP-9 and Exacerbates Neurological Dysfunction in a Mouse Model of Intracerebral Hemorrhage

Extracellular matrix metalloproteinase inducer (EMMPRIN) has been shown to be a vital inflammatory mediator in several neurological and neurodegenerative diseases. However, the role of EMMPRIN in intracerebral hemorrhage (ICH) remains unexplored. In this study, we aimed to exploit a highly selective monoclonal anti-EMMPRIN antibody to functionally inhibit EMMPRIN activity and thus that of MMPs as the downstream effector. To induce ICH pathology, adult C57BL/6 male mice were injected with collagenase type VII or saline as control into the right basal ganglia and were euthanized at different time points. The anti-EMMPRIN monoclonal antibody was intravenously injected once daily for 3 days to block the expression of EMMPRIN initiating at 4 h post-ICH. Western blot and immunofluorescence analysis results revealed that EMMPRIN expression was significantly increased surrounding the hematoma at 3 and 7 d time points after ICH when compared to the saline treated control group. EMMPRIN expression was co-localized with GFAP (astrocytes) and Iba1 (microglia) at 3 d time point post-ICH, but not in the control group mice. The co-localization of EMMPRIN with CD31 in endothelial cells occurred in both groups and was higher in the ICH brain. However, EMMPRIN expression was not detected in neurons from either group. The inhibition of EMMPRIN reduced the expression of MMP-9, the number of infiltrated neutrophils, the degree of brain injury and promoted neurological recovery after ICH. In conclusion, EMMPRIN could mediate the upregulation of MMP-9 and exacerbate neurological dysfunction in a mouse model of experimental ICH. Furthermore, blocking EMMPRIN reduced brain injury and subsequently promoted neurological recovery in ICH mice brains. These outcomes highlight that inhibition of EMMPRIN can be a potential therapeutic intervention strategy to regulate MMP-9's pathological roles during ICH.

Intravenous injection of cyclophilin A realizes the transient and reversible opening of barrier of neural vasculature through basigin in endothelial cells

Neural vasculature forms the blood–brain barrier against the delivery of systemically administered therapeutic drugs into parenchyma of neural tissues. Therefore, procedures to open the blood–brain barrier with minimal damage to tissues would lead to the great progress in therapeutic strategy for intractable neural diseases. In this study, through analyses with mouse in vitro brain microvascular endothelial cells and in vivo neural vasculature, we demonstrate that the administration of cyclophilin A (CypA), a ligand of basigin which is expressed in barrier-forming endothelial cells, realizes the artificial opening of blood–brain barrier. Monolayers of endothelial cells lost their barrier properties through the disappearance of claudin-5, an integral tight junction molecule, from cell membranes in a transient and reversible manner. Furthermore, the intravenous injection of a single dose of CypA into mice resulted in the opening of blood–brain barrier for a certain period which enabled the enhanced delivery of systemically administered doxorubicin into the parenchyma of neural tissues. These findings that the pre-injection of a single dose of CypA realizes an artificial, transient as well as reversible opening of blood–brain barrier are considered to be a great step toward the establishment of therapeutic protocols to overcome the intractability of neural diseases.

GPR120 Signaling Controls Amyloid-β Degrading Activity of Matrix Metalloproteinases

Alzheimer's disease (AD) is characterized by the extensive deposition of amyloid-β peptide (Aβ) in the brain. Brain Aβ level is regulated by a balance between Aβ production and clearance. The clearance rate of Aβ is decreased in the brains of sporadic AD patients, indicating that the dysregulation of Aβ clearance mechanisms affects the pathologic process of AD. Astrocytes are among the most abundant cells in the brain and are implicated in the clearance of brain Aβ via their regulation of the blood-brain barrier, glymphatic system, and proteolytic degradation. The cellular morphology and activity of astrocytes are modulated by several molecules, including ω3 polyunsaturated fatty acids, such as docosahexaenoic acid, which is one of the most abundant lipids in the brain, via the G protein-coupled receptor GPR120/FFAR4. In this study, we analyzed the role of GPR120 signaling in the Aβ-degrading activity of astrocytes. Treatment with the selective antagonist upregulated the matrix metalloproteinase (MMP) inhibitor-sensitive Aβ-degrading activity in primary astrocytes. Moreover, the inhibition of GPR120 signaling increased the levels of Mmp2 and Mmp14 mRNAs, and decreased the expression levels of tissue inhibitor of metalloproteinases 3 (Timp3) and Timp4, suggesting that GPR120 negatively regulates the astrocyte-derived MMP network. Finally, the intracerebral injection of GPR120-specific antagonist substantially decreased the levels of TBS-soluble Aβ in male AD model mice, and this effect was canceled by the coinjection of an MMP inhibitor. These data indicate that astrocytic GPR120 signaling negatively regulates the Aβ-degrading activity of MMPs.SIGNIFICANCE STATEMENT The level of amyloid β (Aβ) in the brain is a crucial determinant of the development of Alzheimer's disease. Here we found that astrocytes, which are the most abundant cell type in the CNS, harbor degrading activity against Aβ, which is regulated by GPR120 signaling. GPR120 is involved in the inflammatory response and obesity in peripheral organs. However, the pathophysiological role of GPR120 in Alzheimer's disease remains unknown. We found that selective inhibition of GPR120 signaling in astrocytes increased the Aβ-degrading activity of matrix metalloproteases. Our results suggest that GPR120 in astrocytes is a novel therapeutic target for the development of anti-Aβ therapeutics.

Novel gene-encoded intermolecular FRET sensor for tracking glycosylation of CD147 in living cells

CD147 is involved in various physiological processes and plays important roles for tumor metastasis. Glycosylation of the protein determines numerous functions of CD147. Up to now, hardly any sensor has been developed for detecting glycosylation of CD147 in live cells. There is a pressing requirement of development of a selective and continuous biosensor for cell imaging. The emergence of gene-encoded fluorescence resonance energy transfer (FRET) sensor provides a new way to develop the sensors to analysts. We designed and constructed novel gene-encoded FRET proteins sensing glycosylation of CD147 by measuring FRET ratio of two intermolecular motifs. With the decrease of CD147 glycosylation level in cells, the FRET ratio increased significantly. The specificity of the sensor targeting to CD147 was also determined by siRNA interference experiment. Finally, continuous living cell image of deglycosylation process of CD147 using the newly developed sensor has been performed successfully. The work not only provides useful tools for analyzing glycosylation of CD147 in living cells, but also implicates alternative strategy for detecting other glycosylated proteins.

4-Methoxyphenyl (E)-3-(Furan-3-yl) Acrylate Inhibits Vascular Smooth Muscle Cell Proliferation

The Cordyceps extract exhibits antiproliferative potential in vascular smooth muscle cells (SMCs) through the mitogen-activated protein kinase signaling pathway. In this study, we aimed to identify the active compounds in the Cordyceps extract and analyze their role in remodeling the arterial wall. On investigation, we discovered the following active compound: 4-methoxyphenyl (E)-3-(furan-3-yl) acrylate and synthesized it. We performed antiproliferation and antimigration assays in addition to an in vivo vessel wall remodeling experiment. Investigation of the mechanism adopted by the active compound to remodel the vessel was performed. The newly synthesized compound inhibited the proliferation and migration of SMCs. Treatment with the synthesized compound reduced neointima formation in the balloon-injured Sprague-Dawley rat model. In addition, this compound inhibited the activation of matrix metalloproteinase-2 and matrix metalloproteinase-9 in type I collagen-activated SMCs. Moreover, this compound suppressed the expression of cycloxygenase-2 (COX-2) in SMCs. Therefore, this compound can exert potential antiarteriosclerotic effects by modulating vessel wall remodeling. In conclusion, the newly synthesized 4-methoxyphenyl (E)-3-(furan-3-yl) acrylate might be an alternative therapeutic intervention for the treatment of atherosclerosis.

Astrocytes in the regulation of cerebrovascular functions

Astrocytes are the most numerous type of neuroglia in the brain and have a predominant influence on the cerebrovascular system; they control perivascular homeostasis, the integrity of the blood-brain barrier, the dialogue with the peripheral immune system, the transfer of metabolites from the blood, and blood vessel contractility in response to neuronal activity. These regulatory processes occur in a specialized interface composed of perivascular astrocyte extensions that almost completely cover the cerebral blood vessels. Scientists have only recently started to study how this interface is formed and how it influences cerebrovascular functions. Here, we review the literature on the astrocytes' role in the regulation of the cerebrovascular system. We cover the anatomy and development of the gliovascular interface, the known gliovascular functions, and molecular factors, the latter's implication in certain pathophysiological situations, and recent cutting-edge experimental tools developed to examine the astrocytes' role at the vascular interface. Finally, we highlight some open questions in this field of research.

The Combination of CD147 and MMP-9 Serum Levels Is Identified as Novel Chemotherapy Response Markers of Advanced Non-Small-Cell Lung Cancer

To evaluate the correlation between the changes in serum concentrations of cluster of differentiation-147 (scCD147) and chemotherapy outcome in patients with NSCLC and evaluate the combination of scCD147 with serum matrix metalloproteinase-9 (scMMP-9) levels in the prediction of chemotherapy response, eighty-two patients with advanced LC were enrolled. Newly diagnosed cases were treated with platinum-based chemotherapy. We measured scCD147 protein levels in LC cases by ELISA and used receiver operating characteristic (ROC) curves to analyze the results. Four time points were chosen to examine the association between the changes in scCD147 and chemotherapy outcome: before chemotherapy and 21 days after the start of the first, second, and fourth chemotherapy cycles. We assessed the combination of scCD147 and scMMP-9 serum levels in predicting the chemotherapy response. scCD147 was higher in LC cases than that in healthy volunteers (HVs). scCD147 was associated with distant metastases and TNM stage. scCD147 and scMMP-9 appeared to be independent predictive factors for chemotherapy outcomes after the first and second chemotherapy cycles for patients with NSCLC. Multivariable analysis also demonstrated that variations in scCD147 and scMMP-9 could be independent factors for monitoring chemotherapy outcome for patients with NSCLC. Furthermore, when scCD147 and scMMP-9 are combined into a new risk model, it has a markedly better prediction of chemotherapy outcomes than each protein alone. scCD147 and MMP-9 are potential predictive biomarkers for efficacy, and their combination significantly improves the predictive power for chemotherapy response in patients with NSCLC.

EMMPRIN/CD147 plays a detrimental role in clinical and experimental ischemic stroke

Background: Ischemic stroke is a devastating disease, often resulting in death or permanent neurological deficits. EMMPRIN/CD147 is a plasma membrane protein that induces the production of matrix metalloproteinases (MMPs), which contribute to secondary damage after stroke by disrupting the blood brain barrier (BBB) and facilitating peripheral leukocyte infiltration into the brain.

Results: CD147 surface expression increased significantly after stroke on infiltrating leukocytes, astrocytes and endothelial cells, but not on resident microglia. Inhibition of CD147 reduced MMP levels, decreased ischemic damage, and improved functional, cognitive and histological outcomes after experimental ischemic stroke in both young and aged mice. In stroke patients, high levels of serum CD147 24 hours after stroke predicted poor functional outcome at 12 months. Brain CD147 levels were correlated with MMP-9 and secondary hemorrhage in post-mortem samples from stroke patients.

Conclusions: Acute inhibition of CD147 decreases levels of MMP-9, limits tissue loss, and improves long-term cognitive outcomes following experimental stroke in aged mice. High serum CD147 correlates with poor outcomes in stroke patients. This study identifies CD147 as a novel, clinically relevant target in ischemic stroke.

Cyclophilin a signaling induces pericyte-associated blood-brain barrier disruption after subarachnoid hemorrhage

Objective

The potential roles and mechanisms of pericytes in maintaining blood–brain barrier (BBB) integrity, which would be helpful for the development of therapeutic strategies for subarachnoid hemorrhage (SAH), remain unclear. We sought to provide evidence on the potential role of pericytes in BBB disruption and possible involvement and mechanism of CypA signaling in both cultured pericytes and SAH models.

Methods

Three hundred fifty-three adult male C57B6J mice weighing 22 to 30 g, 29 CypA^−/− mice, 30 CypA^+/+ (flox/flox) mice, and 30 male neonatal C57B6J mice were used to investigate the time course of CypA expression in pericytes after SAH, the intrinsic function and mechanism of CypA in pericytes, and whether the known receptor CD147 mediates these effects.

Results

Our data demonstrated both intracellular CypA and CypA secretion increased after SAH and could activate CD147 receptor and downstream NF-κB pathway to induce MMP9 expression and proteolytic functions for degradation of endothelium tight junction proteins and basal membranes. CypA served as autocrine or paracrine ligand for its receptor, CD147. Although CypA could be endocytosed by pericytes, specific endocytosis inhibitor chlorpromazine did not have any effect on MMP9 activation. However, specific knockdown of CD147 could reverse the harmful effects of CypA expression in pericytes on the BBB integrity after SAH.

Conclusions

This study demonstrated for the first time that CypA mediated the harmful effects of pericytes on BBB disruption after SAH, which potentially mediated by CD147/NF-κB/MMP9 signal, and junction protein degradation in the brain. By targeting CypA and pericytes, this study may provide new insights on the management of SAH patients.

Chronic sleep fragmentation shares similar pathogenesis with neurodegenerative diseases: Endosome-autophagosome-lysosome pathway dysfunction and microglia-mediated neuroinflammation

Aims

Insufficient sleep has been found to result in varying degrees of cognitive impairment and emotional changes. Sleep was reported probably responsible for cleaning metabolic wastes in brain by increasing extracellular bulk flow. Herein, we propose that chronic sleep insufficiency in young adult wild‐type mice is also linked with dysfunction of intracellular protein degradation pathways and microglia‐mediated neuroinflammation, which are potentially important mechanisms in the initiation of neurodegeneration.

Methods

We applied the chronic sleep fragmentation (CSF) model to induce chronic sleep insufficiency in wild‐type mice. After 2 months of CSF, cognitive function, amyloid‐β accumulation, dysfunction of endosome‐autophagosome‐lysosome pathway, and microglia activation were evaluated.

Results

Following CSF, impairment of spatial learning and memory, and aggravated anxiety‐like behavior in mice were identified by behavioral experiments. Increased intracellular amyloid‐β accumulation was observed in cortex and hippocampus. Mechanistically, CSF could significantly enhance the expression of Rab5 (early endosome marker), Rab7 (late endosome marker), as well as LC3B (autophagosome marker), and autophagy‐positive regulatory factors in brain detected by immunofluorescent staining and Western blot. In addition, activation of microglia was evident by enhanced CD68, CD16/32, and CD206 levels after CSF treatment.

Conclusions

Chronic sleep fragmentation could initiate pathogenetic processes similar to the early stage of neurodegeneration, including dysfunction of endosome‐autophagosome‐lysosome pathway and microglia‐mediated neuroinflammation. Our findings further strengthen the link between chronic sleep insufficiency and the initiation of neurodegeneration even if lack of genetic predisposition.

The CD147-HYALURONAN Axis in Cancer

CD147 (basigin; EMMPRIN), hyaluronan, and hyaluronan receptors (e.g., CD44) are intimately involved in several phenomena that underlie malignancy. A major avenue whereby they influence tumor progression is most likely their role in the characteristics of cancer stem cells (CSCs), subpopulations of tumor cells that exhibit chemoresistance, invasiveness, and potent tumorigenicity. Both CD147 and hyaluronan have been strongly implicated in chemoresistance and invasiveness, and may be drivers of CSC characteristics, since current evidence indicates that both are involved in epithelial-mesenchymal transition, a crucial process in the acquisition of CSC properties. Hyaluronan is a prominent constituent of the tumor microenvironment whose interactions with cell surface receptors influence several signaling pathways that lead to chemoresistance and invasiveness. CD147 is an integral plasma membrane glycoprotein of the Ig superfamily and cofactor in assembly and activity of monocarboxylate transporters (MCTs). CD147 stimulates hyaluronan synthesis and interaction of hyaluronan with its receptors, in particular CD44 and LYVE-1, which in turn result in activation of multiprotein complexes containing members of the membrane-type matrix metalloproteinase, receptor tyrosine kinase, ABC drug transporter, or MCT families within lipid raft domains. Multivalent hyaluronan-receptor interactions are essential for formation or stabilization of these lipid raft complexes and for downstream signaling pathways or transporter activities. We conclude that stimulation of hyaluronan-receptor interactions by CD147 and the consequent activities of these complexes may be critical to the properties of CSCs and their role in malignancy. Anat Rec, 2019. © 2019 Wiley Periodicals, Inc.

Liquefaction of the Brain following Stroke Shares a Similar Molecular and Morphological Profile with Atherosclerosis and Mediates Secondary Neurodegeneration in an Osteopontin-Dependent Mechanism

Here we used mouse models of heart and brain ischemia to compare the inflammatory response to ischemia in the heart, a protein rich organ, to the inflammatory response to ischemia in the brain, a lipid rich organ. We report that ischemia-induced inflammation resolves between one and four weeks in the heart compared to between eight and 24 weeks in the brain. Importantly, we discovered that a second burst of inflammation occurs in the brain between four and eight weeks following ischemia, which coincided with the appearance of cholesterol crystals within the infarct. This second wave shares a similar cellular and molecular profile with atherosclerosis and is characterized by high levels of osteopontin (OPN) and matrix metalloproteinases (MMPs). In order to test the role of OPN in areas of liquefactive necrosis, OPN^-/- mice were subjected to brain ischemia. We found that at seven weeks following stroke, the expression of pro-inflammatory proteins and MMPs was profoundly reduced in the infarct of the OPN^-/- mice, although the number of cholesterol crystals was increased. OPN^-/- mice exhibited faster recovery of motor function and a higher number of neuronal nuclei (NeuN) positive cells in the peri-infarct area at seven weeks following stroke. Based on these findings we propose that the brain liquefies after stroke because phagocytic cells in the infarct are unable to efficiently clear cholesterol rich myelin debris, and that this leads to the perpetuation of an OPN-dependent inflammatory response characterized by high levels of degradative enzymes.

Recent advances in the mechanisms of neuroinflammation and their roles in neurodegeneration

Neuroinflammation is associated with the pathogenesis of many neurological disorders including Parkinson's disease, Alzheimer's disease, Amyotrophic lateral sclerosis and Huntington disease. Current studies in this area have advanced the mechanism of neuroinflammation and its role in neurodegeneration. Studies from epidemiologic, clinical and animal models also contributed in the various new mechanisms of neuroinflammation. In this line, activation of monocytes is an important emerging mechanism that has a, profound role in neuroinflammation and neurodegeneration. Ion channels, matrix metalloproteases and microRNAs are also found to be the key players in the pathogenesis of neuroinflammation. In particular, microRNA-32 regulates microglia-mediated neuroinflammation and thus neurodegeneration. Notably, some important studies describe the role of Th17 cells in neuroinflammation, but, very little knowledge is available about their mechanism of action. Particularly, the role of autophagy gets emphasized, which plays a very critical role in protein aggregation and neurodegeneration. In this review, we highlight and discuss the mechanisms of these mediators of inflammation by which they contribute to the disease progression. In conclusion, we focus on the various newer molecular mechanisms that are associated with the basic understanding of neuroinflammation in neurodegeneration.

From the Bottom-Up: Chemotherapy and Gut-Brain Axis Dysregulation

The central nervous system and gastrointestinal tract form the primary targets of chemotherapy-induced toxicities. Symptoms associated with damage to these regions have been clinically termed chemotherapy-induced cognitive impairment and mucositis. Whilst extensive literature outlines the complex etiology of each pathology, to date neither chemotherapy-induced side-effect has considered the potential impact of one on the pathogenesis of the other disorder. This is surprising considering the close bidirectional relationship shared between each organ; the gut-brain axis. There are complex multiple pathways linking the gut to the brain and vice versa in both normal physiological function and disease. For instance, psychological and social factors influence motility and digestive function, symptom perception, and behaviors associated with illness and pathological outcomes. On the other hand, visceral pain affects central nociception pathways, mood and behavior. Recent interest highlights the influence of functional gut disorders, such as inflammatory bowel diseases and irritable bowel syndrome in the development of central comorbidities. Gut-brain axis dysfunction and microbiota dysbiosis have served as key portals in understanding the potential mechanisms associated with these functional gut disorders and their effects on cognition. In this review we will present the role gut-brain axis dysregulation plays in the chemotherapy setting, highlighting peripheral-to-central immune signaling mechanisms and their contribution to neuroimmunological changes associated with chemotherapy exposure. Here, we hypothesize that dysregulation of the gut-brain axis plays a major role in the intestinal, psychological and neurological complications following chemotherapy. We pay particular attention to evidence surrounding microbiota dysbiosis, the role of intestinal permeability, damage to nerves of the enteric and peripheral nervous systems and vagal and humoral mediated changes.

Extracellular matrix metalloproteinase inducer (EMMPRIN) is a potential biomarker of angiogenesis in proliferative diabetic retinopathy

PURPOSE

Extracellular matrix metalloproteinase inducer (EMMPRIN) promotes angiogenesis through matrix metalloproteinases (MMPs) and vascular endothelial growth factor (VEGF) production. We investigated the expression levels of EMMPRIN and correlated these levels with VEGF, MMP-1 and MMP-9 in proliferative diabetic retinopathy (PDR). In addition, we examined the expression of EMMPRIN in the retinas of diabetic rats and the effect of EMMPRIN on the induction of angiogenesis regulatory factors in human retinal microvascular endothelial cells (HRMECs).

METHODS

Vitreous samples from 40 PDR and 19 non-diabetic patients, epiretinal membranes from 12 patients with PDR, retinas of rats and HRMECs were studied by enzyme-linked immunosorbent assay (ELISA), immunohistochemistry, Western blot analysis, zymography analysis and RT-PCR.

RESULTS

We showed a significant increase in the expression of EMMPRIN, VEGF, MMP-1 and MMP-9 in vitreous samples from PDR patients compared with non-diabetic controls (p < 0.0001; p = 0.001; p = 0.009; p < 0.0001, respectively). Significant positive correlations were found between the levels of EMMPRIN and the levels of VEGF (r = 0.38; p = 0.003), MMP-1 (r = 0.36; p = 0.005) and MMP-9 (r = 0.46; p = 0.003). In epiretinal membranes, EMMPRIN was expressed in vascular endothelial cells and stromal cells. Significant increase of EMMPRIN mRNA was detected in rat retinas after induction of diabetes. EMMPRIN induced hypoxia-inducible factor-1α, VEGF and MMP-1 expression in HRMEC.

CONCLUSIONS

These results suggest that EMMPRIN/MMPs/VEGF pathway is involved in PDR angiogenesis.

Nuclear envelope-distributed CD147 interacts with and inhibits the transcriptional function of RING1 and promotes melanoma cell motility

Melanoma accounts for nearly 80% of all deaths associated with skin cancer.CD147 plays a very important role in melanoma progression and the expression level may correlate with tumor malignancy. RING1 can bind DNA and act as a transcriptional repressor, play an important role in the aggressive phenotype in melanoma. The interactions between CD147 and RING1 were identified with a yeast two-hybrid and RING1 interacted with CD147 through the transmembrane domain. RING1 inhibits CD147's capability promoting melanoma cell migration. In conclusion, the study identified novel interactions between CD147 and RING1, recovered CD147 nuclear envelope distribution in melanoma cells, and suggested a new mechanism underlying how cytoplasmic CD147 promotes melanoma development.

EMMPRIN overexpression in SVZ neural progenitor cells increases their migration towards ischemic cortex

Stimulation of endogenous neurogenesis and recruitment of neural progenitors from the subventricular zone (SVZ) neurogenic site may represent a useful strategy to improve regeneration in the ischemic cortex. Here, we tested whether transgenic overexpression of extracellular matrix metalloproteinase inducer (EMMPRIN), the regulator of matrix metalloproteinases (MMPs) expression, in endogenous neural progenitor cells (NPCs) in the subventricular zone (SVZ) could increase migration towards ischemic injury. For this purpose, we applied a lentivector-mediated gene transfer system. We found that EMMPRIN-transduced progenitors exhibited enhanced MMP-2 activity in vitro and showed improved motility in 3D collagen gel as well as in cortical slices. Using a rat model of neonatal ischemia, we showed that EMMPRIN overexpressing SVZ cells invade the injured cortical tissue more efficiently than controls. Our results suggest that EMMPRIN overexpression could be suitable approach to improve capacities of endogenous or transplanted progenitors to invade the injured cortex.

The origin and evolution of Basigin(BSG) gene: A comparative genomic and phylogenetic analysis

Basigin (BSG), also known as extracellular matrix metalloproteinase inducer (EMMPRIN) or cluster of differentiation 147 (CD147), plays various fundamental roles in the intercellular recognition involved in immunologic phenomena, differentiation, and development. In this study, we aimed to compare the similarities and differences of BSG among organisms and explore possible evolutionary relationships based on the comparison result. We used the extensive BLAST tool to search the metazoan genomes, N-glycosylation sites, the transmembrane region and other functional sites. We then identified BSG homologs from genomic sequences and analyzed their phylogenetic relationships. We identified that BSG genes exist not only in the vertebrate metazoans but also in the invertebrate metazoans such as Amphioxus B. floridae, D. melanogaster, A. mellifera, S. japonicum, C. gigas, and T. patagoniensis. After sequence analysis, we confirmed that only vertebrate metazoans and Cephalochordate (amphioxus B. floridae) have the classic structure (a signal peptide, two Ig-like domains (IgC2 and IgI), a transmembrane region, and an intracellular domain). The invertebrate metazoans (excluding amphioxus B. floridae) lack the N-terminal signal peptides and IgC2 domain. We then generated a phylogenetic tree, genome organization comparison, and chromosomal disposition analysis based on the biological information obtained from the NCBI and Ensembl databases. Finally, we established the possible evolutionary scenario of the BSG gene, which showed the restricted exon rearrangement that has occurred during evolution, forming the present-day BSG gene.

Elevated Serum Cyclophilin B Levels Are Associated with the Prevalence and Severity of Metabolic Syndrome

OBJECTIVE

Inflammation plays a central role in the pathogenesis of metabolic syndrome (MetS). Cyclophilin B (CypB) can be constitutively secreted in response to inflammatory stimuli and oxidative stress, participating in tissue or systemic inflammation. We investigated the relationship between CypB and MetS in both humans and mice.

METHODS

Serum CypB levels were determined in 211 subjects with MetS and 292 subjects without MetS (non-MetS) (133 healthy controls and 159 high-risk subjects with one to two MetS components). Additionally, CypB expression in metabolic organs was examined in mice fed with high-fat diet (HFD) and genetically obese (ob/ob) mice.

RESULTS

Serum CypB level was significantly higher in MetS subjects compared with both groups of non-MetS subjects (193.80 ± 83.22 vs. 168.38 ± 65.01 vs. 124.26 ± 47.83 ng/mL, P < 0.001). Particularly, serum CypB level was significantly higher in subjects with hypertension, central obesity, diabetes mellitus or hyperglycemia, elevated levels of triglycerides, or reduced levels of high-density lipoprotein than in those without. Moreover, CypB was positively associated with the number of MetS components (r = 0.404, P < 0.001), indicating that a higher serum CypB level reflected more severe MetS. Multivariate regression revealed that a one SD increase in CypB was associated with an odds ratio of 1.506 (1.080-2.101, P = 0.016) for MetS prevalence after adjusting for age, gender, conventional risk factors, and medication. Stratified analyses by age and gender demonstrated that subjects >60 years old with higher CypB levels were more likely to have MetS, and the risk for MetS was higher and more significant in women compared with men. Additionally, CypB expression levels were lower at baseline and dramatically enhanced in metabolic organs (such as the liver) and visceral and subcutaneous adipose tissue from HFD-induced obese mice and ob/ob mice.

CONCLUSION

Increased CypB levels were significantly and independently associated with the presence and severity of MetS, indicating that CypB could be used as a novel biomarker and clinical predictor of MetS.

Basigin can be a therapeutic target to restore the retinal vascular barrier function in the mouse model of diabetic retinopathy

Despite the advance in medical technology, diabetic retinopathy (DR) is still an intractable disease which leads to the damage of retinal cells and finally the visual loss. Impairment of retinal vascular barrier triggered by an admixture of multiple inflammatory cytokines is a core of pathophysiology of DR. Therefore, the molecules involved commonly in multiple cytokines-induced impairment of vascular barrier would be the targets of curative treatment of DR. Here, we demonstrate that basigin, a transmembrane molecule expressed in neural barrier-forming endothelial cells, is the molecule essential for vascular barrier impairment which is shared by various triggers including VEGF, TNFα and IL-1β. In vitro data with neural microvascular endothelial cells indicated that stimulation with cytokines decreases the levels of claudin-5 in cell membranes and consequently impairs the barrier function in a manner dependent on the interaction of claudin-5 with basigin and caveolin-1. In addition, the increased vascular permeability in retinas of streptozotocin-induced diabetic mice was shown to be clearly normalized by intravitreous injection of siRNAs specific for basigin. This study has highlighted basigin as a common essential molecule for various stimuli-induced impairment of retinal vascular barrier, which can be a target for strategies to establish a curative treatment of DR.

Knock out of the BASIGIN/CD147 chaperone of lactate/H+ symporters disproves its pro-tumour action via extracellular matrix metalloproteases (MMPs) induction

BASIGIN/CD147/EMMPRIN is a multifunctional transmembrane glycoprotein strongly expressed in tumours. BASIGIN controls tumour metabolism, particularly glycolysis by facilitating lactic acid export through the two monocarboxylate transporters MCT1 and hypoxia-inducible MCT4. However, before being recognized as a co-carrier of MCTs, BASIGIN was described as an inducer of extracellular matrix metalloproteases (MMPs). Early on, a model emerged in which, tumour cells use the extracellular domain of BASIGIN to recognize and stimulate neighbouring fibroblasts to produce MMPs. However, this model has remained hypothetical since a direct link between BASIGIN and MMPs production has not yet been clearly established. To validate the BASIGIN/MMP hypothesis, we developed BASIGIN knockouts in three human tumour cell lines derived from glioma, colon, and lung adenocarcinoma. By using co-culture experiments of either human or mouse fibroblasts and tumour cell lines we showed, contrary to what has been abundantly published, that the disruption of BASIGIN in tumour cells and in MEFs has no action on the production of MMPs. Our findings do not support the notion that the pro-tumoural action of BASIGIN is mediated via induction of MMPs. Therefore, we propose that to date, the strongest pro-tumoural action of BASIGIN is mediated through the control of fermentative glycolysis.

How, with whom and when: an overview of CD147-mediated regulatory networks influencing matrix metalloproteinase activity

Matrix metalloproteinases (MMPs) comprise a family of 23 zinc-dependent enzymes involved in various pathologic and physiologic processes. In cancer, MMPs contribute to processes from tumour initiation to establishment of distant metastases. Complex signalling and protein transport networks regulate MMP synthesis, cell surface presentation and release. Earlier attempts to disrupt MMP activity in patients have proven to be intolerable and with underwhelming clinical efficacy; thus targeting ancillary proteins that regulate MMP activity may be a useful therapeutic approach. Extracellular matrix metalloproteinase inducer (EMMPRIN) was originally characterized as a factor present on lung cancer cells, which stimulated collagenase (MMP-1) production in fibroblasts. Subsequent studies demonstrated that EMMPRIN was identical with several other protein factors, including basigin (Bsg), all of which are now commonly termed CD147. CD147 modulates the synthesis and activity of soluble and membrane-bound [membrane-type MMPs (MT-MMPs)] in various contexts via homophilic/heterophilic cell interactions, vesicular shedding or cell-autonomous processes. CD147 also participates in inflammation, nutrient and drug transporter activity, microbial pathology and developmental processes. Despite the hundreds of manuscripts demonstrating CD147-mediated MMP regulation, the molecular underpinnings governing this process have not been fully elucidated. The present review summarizes our present knowledge of the complex regulatory systems influencing CD147 biology and provides a framework to understand how CD147 may influence MMP activity.

The Cyclophilin A-CD147 complex promotes the proliferation and homing of multiple myeloma cells

B cell malignancies frequently colonize the bone marrow. The mechanisms responsible for this preferential homing are incompletely understood. Here we studied multiple myeloma (MM) as a model of a terminally differentiated B cell malignancy that selectively colonizes the bone marrow. We found that extracellular CyPA (eCyPA), secreted by bone marrow endothelial cells (BMECs), promoted the colonization and proliferation of MM cells in an in vivo scaffold system via binding to its receptor, CD147, on MM cells. The expression and secretion of eCyPA by BMECs was enhanced by BCL9, a Wnt-β-catenin transcriptional coactivator that is selectively expressed by these cells. eCyPA levels were higher in bone marrow serum than in peripheral blood in individuals with MM, and eCyPA-CD147 blockade suppressed MM colonization and tumor growth in the in vivo scaffold system. eCyPA also promoted the migration of chronic lymphocytic leukemia and lymphoplasmacytic lymphoma cells, two other B cell malignancies that colonize the bone marrow and express CD147. These findings suggest that eCyPA-CD147 signaling promotes the bone marrow homing of B cell malignancies and offer a compelling rationale for exploring this axis as a therapeutic target for these malignancies.

Melanoma cell adhesion molecule-positive CD8 T lymphocytes mediate central nervous system inflammation

OBJECTIVE

Although Tc17 lymphocytes are enriched in the central nervous system (CNS) of multiple sclerosis (MS) subjects and of experimental autoimmune encephalomyelitis (EAE) animals, limited information is available about their recruitment into the CNS and their role in neuroinflammation. Identification of adhesion molecules used by autoaggressive CD8(+) T lymphocytes to enter the CNS would allow further characterization of this pathogenic subset and could provide new therapeutic targets in MS. We propose that melanoma cell adhesion molecule (MCAM) is a surface marker and adhesion molecule used by pathogenic CD8(+) T lymphocytes to access the CNS.

METHODS

Frequency, phenotype, and function of MCAM(+) CD8(+) T lymphocytes was characterized using a combination of ex vivo, in vitro, in situ, and in vivo approaches in humans and mice, including healthy controls, MS subjects, and EAE animals.

RESULTS

Herein, we report that MCAM is expressed by human effector CD8(+) T lymphocytes and it is strikingly upregulated during MS relapses. We further demonstrate that MCAM(+) CD8(+) T lymphocytes express more interleukin 17, interferon γ, granulocyte-macrophage colony-stimulating factor, and tumor necrosis factor than MCAM(-) lymphocytes, and exhibit an enhanced killing capacity toward oligodendrocytes. MCAM blockade restricts the transmigration of CD8(+) T lymphocytes across human blood-brain barrier endothelial cells in vitro, and blocking or depleting MCAM in vivo reduces chronic neurological deficits in active, transfer, and spontaneous progressive EAE models.

INTERPRETATION

Our data demonstrate that MCAM identifies encephalitogenic CD8(+) T lymphocytes, suggesting that MCAM could represent a biomarker of MS disease activity and a valid target for the treatment of neuroinflammatory conditions.

The role of EMMPRIN in T cell biology and immunological diseases

Review on EMMPRIN in numerous immunological/inflammatory disease conditions and its complex roles in T cell biology.

EMMPRIN (CD147), originally described as an inducer of the expression of MMPs, has gained attention in its involvement in various immunologic diseases, such that anti‐EMMPRIN antibodies are considered as potential therapeutic medications. Given that MMPs are involved in the pathogenesis of various disease states, it is relevant that targeting an upstream inducer would make for an effective therapeutic strategy. Additionally, EMMPRIN is now appreciated to have multiple roles apart from MMP induction, including in cellular functions, such as migration, adhesion, invasion, energy metabolism, as well as T cell activation and proliferation. Here, we review what is known about EMMPRIN in numerous immunologic/inflammatory disease conditions with a particular focus on its complex roles in T cell biology.

CD147: regulator of hyaluronan signaling in invasiveness and chemoresistance

Major determinants that influence negative outcome in cancer patients are the abilities of cancer cells to resist current therapies and to invade surrounding host tissue, consequently leading to local and metastatic dissemination. Hyaluronan (HA), a prominent constituent of the tumor microenvironment, not only provides structural support but also interacts with cell surface receptors, especially CD44, that influence cooperative signaling pathways leading to chemoresistance and invasiveness. CD147 (emmprin; basigin) is a member of the Ig superfamily that has also been strongly implicated in chemoresistance and invasiveness. CD147 both regulates HA synthesis and interacts with the HA receptors, CD44, and LYVE-1. Increased CD147 expression induces formation of multiprotein complexes containing CD44 (or LYVE-1) as well as members of the membrane-type matrix metalloproteinase, receptor tyrosine kinase, ABC drug transporter, or monocarboxylate transporter families, which become assembled in specialized lipid raft domains along with CD147 itself. In each case, multivalent HA-receptor interactions are essential for formation or stabilization of the lipid raft complexes and for downstream signaling pathways or transporter activities that are driven by these complexes. We conclude that cooperativity between HA, HA receptors, and CD147 may be a major driver of the interconnected pathways of invasiveness and chemoresistance widely critical to malignancy.

Enhanced expression of matrix metalloproteinase-12 contributes to Npc1 deficiency-induced axonal degeneration

Niemann-Pick type C (NPC) disease is a genetic disorder associated with intracellular cholesterol accumulation in the brain and other organs, and neurodegeneration is generally believed to be the fatal cause of the disease. In view of the emerging role of matrix metalloproteinase-12 (MMP-12) in neuronal injury, we investigated its expression and potential roles in axonal degeneration in Npc1-/- mouse brain. Microarray and quantitative real-time reversed transcription PCR analysis indicated a marked increase in MMP-12 mRNA levels in cerebellum of 3 week-old Npc1-/- mice, as compared to wild-type littermates. Western blots showed that the ratio of mature MMP-12 over pro-MMP-12 was significantly increased in cerebellum of Npc1-/-, as compared to wild-type mice. Immunohistochemical studies confirmed that MMP-12 expression was increased, especially in the cell bodies of Purkinje neurons in Npc1-/- mice. Neuritic growth was significantly reduced by Npc1 siRNA knockdown in nerve growth factor-differentiated PC-12 cells, and this effect was completely reversed by treatment with an MMP-12 specific inhibitor. Furthermore, in vivo experiments showed that chronic treatment with the MMP-12 inhibitor ameliorated Npc1 deficiency-induced axonal pathology in the striatum. Our results indicate that abnormal neuronal expression of MMP-12 may contribute to axonal degeneration in NPC disease, thus providing a potential novel target for treatment.

The roles of CD147 and/or cyclophilin A in kidney diseases

CD147 is a widely expressed integral plasma membrane glycoprotein and has been involved in a variety of physiological and pathological activities in combination with different partners, including cyclophilins, caveolin-1, monocarboxylate transporters, and integrins. Recent data demonstrate that both CyPA and CD147 significantly contribute to renal inflammation, acute kidney injury, renal fibrosis, and renal cell carcinoma. Here we review the current understanding of cyclophilin A and CD147 expression and functions in kidney diseases and potential implications for treatment of kidney diseases.

Functional role of EMMPRIN in the formation and mineralisation of dental matrix in mouse molars

Our previous research has shown that the extracellular matrix metalloproteinase inducer (EMMPRIN) is expressed during and may function in the early development of tooth germs. In the present study, we observed the specific expression of EMMPRIN in ameloblasts and odontoblasts during the middle and late stages of tooth germ development using immunohistochemistry. Furthermore, to extend our understanding of the function of EMMPRIN in odontogenesis, we used an anti-EMMPRIN function-blocking antibody to remove EMMPRIN activity in tooth germ culture in vitro. Both the formation and mineralisation of dental hard tissues were suppressed in the tooth germ culture after the abrogation of EMMPRIN. Meanwhile, significant reductions in VEGF, MMP-9, ALPL, ameloblastin, amelogenin and enamelin expression were observed in antibody-treated tooth germ explants compared to control and normal serum-treated explants. The current results illustrate that EMMPRIN may play a critical role in the processing and maturation of the dental matrix.

Hepatocyte produced matrix metalloproteinases are regulated by CD147 in liver fibrogenesis

BACKGROUND

The classical paradigm of liver injury asserts that hepatic stellate cells (HSC) produce, remodel and turnover the abnormal extracellular matrix (ECM) of fibrosis via matrix metalloproteinases (MMPs). In extrahepatic tissues MMP production is regulated by a number of mechanisms including expression of the glycoprotein CD147. Previously, we have shown that CD147 is expressed on hepatocytes but not within the fibrotic septa in cirrhosis [1]. Therefore, we investigated if hepatocytes produce MMPs, regulated by CD147, which are capable of remodelling fibrotic ECM independent of the HSC.

METHODS

Non-diseased, fibrotic and cirrhotic livers were examined for MMP activity and markers of fibrosis in humans and mice. CD147 expression and MMP activity were co-localised by in-situ zymography. The role of CD147 was studied in-vitro with siRNA to CD147 in hepatocytes and in-vivo in mice with CCl4 induced liver injury using ãCD147 antibody intervention.

RESULTS

In liver fibrosis in both human and mouse tissue MMP expression and activity (MMP-2, -9, -13 and -14) increased with progressive injury and localised to hepatocytes. Additionally, as expected, MMPs were abundantly expressed by activated HSC. Further, with progressive fibrosis there was expression of CD147, which localised to hepatocytes but not to HSC. Functionally significant in-vitro regulation of hepatocyte MMP production by CD147 was demonstrated using siRNA to CD147 that decreased hepatocyte MMP-2 and -9 expression/activity. Further, in-vivo α-CD147 antibody intervention decreased liver MMP-2, -9, -13, -14, TGF-β and α-SMA expression in CCl4 treated mice compared to controls.

CONCLUSION

We have shown that hepatocytes produce active MMPs and that the glycoprotein CD147 regulates hepatocyte MMP expression. Targeting CD147 regulates hepatocyte MMP production both in-vitro and in-vivo, with the net result being reduced fibrotic matrix turnover in-vivo. Therefore, CD147 regulation of hepatocyte MMP is a novel pathway that could be targeted by future anti-fibrogenic agents.

β3GnT8 plays an important role in CD147 signal transduction as an upstream modulator of MMP production in tumor cells

Aberrant carbohydration by related glycosyl-transferases plays an important role in the progression of cancer. This study focused on the ablity of β-1,3-N-acetyl-glucosaminyltransferase-8 (β3GnT8) to regulate MMP-2 expression through regulation of the CD147 signal transduction pathway in cancer cells. β3GnT8 catalyzes and then extends a polylactosamine chain specifically on β1-6-branched tetraantennary N-glycans. CD147 is a major carrier of β1-6-branched polylactosamine sugars on tumor cells, and the high glycoform of CD147 (HG-CD147) induces matrix metalloproteinase (MMP) production. In the present study, we analyzed β3GnT8 mRNA expression in 6 cancer cell lines (MCF-7, M231, LN229, U87, SGC-7901 and U251). We found that β3GnT8 expression in the LN229, SGC-7901 and U251 cell lines was higher than that in the other cell lines. Therefore, we established β3GnT8-knockdown cell lines derived from the LN229 and SGC-7901 cell lines to examine the level of polylactosamine and CD147 N-glycosylation. In addition, tunicamycin is widely used as an inhibitor of N-linked glycosylation. Hence, various concentrations of tunicamycin were used to treat the cells in order to study its influence on CD147 N-glycosylation and MMP-2 expression. In conclusion, we found that β3GnT8 regulated the level of N-glycans on CD147 and that N-glycosylation of CD147 has an important effect on MMP-2 expression. Our findings suggest that β3GnT8 affects the signal transduction pathway of MMP-2 by altering the N-glycan structure of CD147.

Importance of N-glycosylation on CD147 for its biological functions

Glycosylation of glycoproteins is one of many molecular changes that accompany malignant transformation. Post-translational modifications of proteins are closely associated with the adhesion, invasion, and metastasis of tumor cells. CD147, a tumor-associated antigen that is highly expressed on the cell surface of various tumors, is a potential target for cancer diagnosis and therapy. A significant biochemical property of CD147 is its high level of glycosylation. Studies on the structure and function of CD147 glycosylation provide valuable clues to the development of targeted therapies for cancer. Here, we review current understanding of the glycosylation characteristics of CD147 and the glycosyltransferases involved in the biosynthesis of CD147 N-glycans. Finally, we discuss proteins regulating CD147 glycosylation and the biological functions of CD147 glycosylation.

Activation of the PKC pathway stimulates ovarian cancer cell proliferation, migration, and expression of MMP7 and MMP10

Postmenopausal women are at a higher risk of ovarian cancer due, in part, to increased levels of gonadotropins such as luteinizing hormone (LH). Gonadotropins and other stimuli are capable of activating two pathways, PKA and PKC, that are altered in ovarian cancer. To determine the role of LH on ovarian cancer, we explored the effects of human chorionic gonadotropin (hCG), an LH mimic, and an activator of the PKC pathway, phorbol-12-myristate 13-acetate (PMA), on ovarian cancer cell-cycle kinetics and apoptosis in Ovcar3 cells. PMA treatment increased cells in the S phase of the cell cycle and initially increased apoptosis after 4 h before diminishing apoptosis after 8 h. Treatment of ovarian cancer cells with hCG had no effect on these parameters. The PKC pathway is known to differentially regulate matrix metalloproteinase (MMP) expression. Results showed that ovarian cancer cells treated with PMA increased MMP7 and MMP10 mRNA levels after 8 h of treatment, and expression remained high after 12 h before decreasing at 24 h. The mRNA expression of extracellular matrix metalloproteinase inducer (BSG), an activator of MMPs, was unaffected by PMA. Due to the role that MMPs play in migration, we investigated the effect of PMA activation of MMPs on ovarian cancer cell migration. The use of the MMP inhibitor GM6001 blocked the increased migratory effects of PMA on ovarian cancer cells. Together, these studies show that activating the PKC pathway causes significant changes in cell cycle kinetics and selective expression of MMPs that are involved in enhancing ovarian cancer cell proliferation and migration.

Proteome profiling of neuroblastoma-derived exosomes reveal the expression of proteins potentially involved in tumor progression

Neuroblastoma (NB) is the most common extracranial solid tumor in childhood, with grim prognosis in a half of patients. Exosomes are nanometer-sized membrane vesicles derived from the multivesicular bodies (MVBs) of the endocytic pathway and released by normal and neoplastic cells. Tumor-derived exosomes have been shown in different model systems to carry molecules that promote cancer growth and dissemination. In this respect, we have here performed the first characterization and proteomic analysis of exosomes isolated from human NB cell lines by filtration and ultracentrifugation. Electron microscopy demonstrated that NB-derived exosomes exhibited the characteristic cup-shaped morphology. Dynamic light scattering studies showed a bell-shaped curve and a polydispersity factor consistent with those of exosomes. Zeta potential values suggested a good nanoparticle stability. We performed proteomic analysis of NB-derived exosomes by two dimension liquid chromatography separation and mass spectrometry analyses using the multidimensional protein identification technology strategy. We found that the large majority of the proteins identified in NB derived exosomes are present in Exocarta database including tetraspanins, fibronectin, heat shock proteins, MVB proteins, cytoskeleton-related proteins, prominin-1 (CD133), basigin (CD147) and B7-H3 (CD276). Expression of the CD9, CD63 and CD81 tetraspanins, fibronectin, CD133, CD147 and CD276 was validated by flow cytometry. Noteworthy, flow cytometric analysis showed that NB-derived exosomes expressed the GD2 disialoganglioside, the most specific marker of NB. In conclusion, this study shows that NB-derived exosomes express a discrete set of molecules involved in defense response, cell differentiation, cell proliferation and regulation of other important biological process. Thus, NB-derived exosomes may play an important role in the modulation of tumor microenvironment and represent potential tumor biomarkers.

CD147 in ovarian and other cancers

Ovarian cancer, a gynecological malignancy, is the most common cause of death in older women worldwide. The overall 5-year survival of ovarian cancer patients is only 20% because of late diagnosis, as well as distant metastasis and multidrug resistance. Therefore, predictive and prognostic markers are urgently required for the early diagnosis of ovarian cancer. CD147, an extracellular matrix metalloproteinase inducer, is overexpressed in ovarian cancers. Current knowledge suggests that CD147 is associated with the survival and progression of ovarian cancer, and is considered as a biomarker of poor outcome. Here, we specifically review the roles of CD147 in ovarian cancer progression and discuss the diagnostic and prognostic value of CD147 in patients with ovarian cancer. CD147 promotes ovarian cancer progression by its involvement in every facet of malignancy, including invasion, metastasis, survival, angiogenesis, and drug resistance. Although it is not fully confirmed, the combination of CD147 with other biomarkers might be of diagnostic value.

Epitope mapping of metuximab on CD147 using phage display and molecular docking

Metuximab is the generic name of Licartin, a new drug for radioimmunotherapy of hepatocellular carcinoma. Although it is known to be a mouse monoclonal antibody against CD147, the complete epitope mediating the binding of metuximab to CD147 remains unknown. We panned the Ph.D.-12 phage display peptide library against metuximab and got six mimotopes. The following bioinformatics analysis based on mimotopes suggested that metuximab recognizes a conformational epitope composed of more than 20 residues. The residues of its epitope may include T28, V30, K36, L38, K57, F74, D77, S78, D79, D80, Q81, G83, S86, N98, Q100, L101, H102, G103, P104, V131, P132, and K191. The homology modeling of metuximab and the docking of CD147 to metuximab were also performed. Based on the top one docking model, the epitope was predicted to contain 28 residues: AGTVFTTV (23–30), I37, D45, E84, V88, EPMGTANIQLH (92–102), VPP (131–133), Q164, and K191. Almost half of the residues predicted on the basis of mimotope analysis also appear in the docking result, indicating that both results are reliable. As the predicted epitopes of metuximab largely overlap with interfaces of CD147-CD147 interactions, a structural mechanism of metuximab is proposed as blocking the formation of CD147 dimer.

An ex vivo study on immunohistochemical localization of MMP-7 and MMP-9 in temporomandibular joint discs with internal derangement

Internal derangement (ID) is among the most common disorders of the temporomandibular joint (TMJ). Previous research by our group highlighted a correlation between apoptosis and TMJ ID. Metalloproteinases (MMP)-7 and -9 have been shown to play an important role in extracellular matrix ECM) homeostasis and, through it, in joint disc remodelling. The immunohistochemical expression of MMP-7 and -9 was investigated in discs from patients with TMJ ID and from healthy donors and compared with the degree of histological tissue degeneration. The collagen fibre arrangement in pathological discs exhibited varying degrees of disruption. New vessels were consistently detected; endothelial cells from these vessels were immunolabelled with both MMP-7 and MMP-9. More or less intense MMP-7 and MMP-9 immunolabelling was detected in the cytoplasm of disc cells from all patients. MMP-7 and MMP-9 immunostaining was significantly different between pathological and normal discs and correlated with the extent of histopathological degeneration. MMP-7 and MMP-9 upregulation in discs from patients with TMJ ID demonstrates their involvement in disc damage in this disorder. A greater understanding of these processes could help identify ways to curb MMP overproduction without affecting their tissue remodelling action. The design of specific inhibitors for these MMPs would not only help to gain insights into the biological roles of MMPs, but would also aid in developing therapeutic interventions for diseases associated with abnormal ECM degradation.