Matrix metalloproteinases in subjects with type 1 diabetes

Regulation of cardiac ferroptosis in diabetic human heart failure: uncovering molecular pathways and key targets

Diabetes significantly increases the risk of heart failure by inducing myocardial cell death, potentially through ferroptosis-an iron-dependent, non-apoptotic cell death pathway characterized by lipid peroxidation. The role of cardiac ferroptosis in human heart failure, however, remains poorly understood. In this study, we compared cardiac ferroptosis in humans with diabetic heart failure to that in healthy controls. Our findings reveal that diabetes not only intensifies myocardial cell death but also upregulates markers of ferroptosis in human hearts. This is linked to decreased transcription and activity of glutathione peroxidase-4 (GPX4), influenced by reduced levels of activating transcription factor-4 (ATF4) and nuclear factor erythroid-2-related factor-2 (NRF2), and downregulation of glutathione reductase (GSR). Additionally, diabetic hearts showed an increased labile iron pool due to enhanced heme metabolism by heme oxygenase-1 (HMOX1), elevated iron import via divalent metal transporter-1 (DMT1), reduced iron storage through ferritin light chain (FLC), and decreased iron export via ferroportin-1 (FPN1). The reduction in FPN1 levels likely results from decreased stabilization by amyloid precursor protein (APP) and diminished NRF2-mediated transcription. Furthermore, diabetes upregulates lysophosphatidylcholine acyltransferase-3 (LPCAT3), facilitating the integration of polyunsaturated fatty acids (PUFA) into phospholipid membranes, and downregulates acyl-CoA thioesterase-1 (ACOT1), which further promotes ferroptosis. LC-MS/MS analysis identified several novel proteins implicated in diabetes-induced cardiac ferroptosis, including upregulated ceruloplasmin, which enhances iron metabolism, and cytochrome b-245 heavy chain (CYBB), a key component of NADPH oxidase that aids in the production of reactive oxygen species (ROS), along with downregulated voltage-dependent anion-selective channel protein-2 (VDAC2), essential for maintaining mitochondrial membrane potential. In conclusion, our study not only confirms the presence and potentially predominant role of cardiac ferroptosis in humans with diabetic heart failure but also elucidates its molecular mechanisms, offering potential therapeutic targets to mitigate heart failure complications in diabetic patients.

Syndecans and diabetic complications: A narrative review

Syndecan (SDC) is a member of the heparan sulfate proteoglycan (HSPG) family. It appears to play a role in the aetiology of diabetic complications, with decreased levels of SDCs being reported in the kidney, retina, and cardiac muscle in models of diabetes mellitus (DM). The reduced levels of SDCs may play an important role in the development of albuminuria in DM. Some studies have provided the evidence supporting the mechanisms underlying the role of SDCs in DM. However, SDCs and the molecular mechanisms involved are complex and need to be further elucidated. This review focuses on the underlying molecular mechanisms of SDCs that are involved in the development and progression of the complications of DM, which may help in developing new strategies to prevent and treat these complications.

Investigation of the cellular and molecular effects of dehydrozingerone formulation on various days of diabetic wound repair

Cases of diabetes are significantly increasing year by year, attracting the attention of medical professionals and researchers to focus on diabetes and its underlying complications. One among such are diabetic wounds which are difficult to heal, creating severe implications in the day-to-day chores of not only patients, but also family members. Dehydrozingerone (DHZ) is known to possess various effects like anti-inflammatory, anti-microbial, antioxidant, and wound-healing properties. The effect of DHZ on different phases of diabetic wound healing remains untested. Hence, this study was proposed to find out the effect of oral and topical formulation of DHZ on day 5, 10 and 15 of diabetic wound healing. Excisional wounds were created on the dorsal side of animals using punch biopsy to mimic human diabetic wounds. Topical DHZ gel (100 mg in 1 gm of gel) was prepared using 1% Carbopol 934 and was applied twice a day. The treated groups had increased percentage of wound closure; western blotting suggested that DHZ significantly increased ERK and JNK levels and decreased TNF and MMP 2 and 9 levels. From histopathological studies, it was observed that angiogenesis, collagen formation, granulation tissue formation, and fibroblast proliferation were improved on days 5, 10, and 15 of diabetic wound healing. These findings indicate that DHZ (both systemic and topical) are effective during the early phases of wound healing which gets impaired in diabetic wounds. Dehydrozingerone accelerated diabetic wound healing by regulating the various hallmarks of wound healing process.

Galectin-1 correlates with inflammatory markers and T regulatory cells in children with type 1 diabetes and/or celiac disease

Type 1 diabetes (T1D) and celiac disease (CeD) are common autoimmune diseases in children where the pathophysiology is not fully characterized. The autoimmune process involves a complex scenario of both inflammatory and regulatory features. Galectin-1 (GAL-1) has a wide range of biological activities e.g. interaction with immune cells. We examined the relationship between GAL-1 and soluble immune markers and T-cell subsets in a cohort of children with T1D and/or CeD relative to healthy children. GAL-1, together with several soluble immune markers [e.g. interleukins (IL)], tumor necrosis factor (TNF), acute phase proteins, and matrix metalloproteinases (MMP) were measured in sera from children with T1D and/or CeD by fluorochrome (Luminex) technique using children without these diseases as a reference. Subgroups of T cells, including T-regulatory (Treg) cells, were analysed by flow cytometry. Association between GAL-1, pro-inflammatory markers, and Treg cells differed depending on which illness combination was present. In children with both T1D and CeD, GAL-1 correlated positively with pro-inflammatory markers (IL-1β, IL-6, and TNF-α). Composite scores increased the strength of correlation between GAL-1 and pro-inflammatory markers, Th1-associated interferon (IFN)-γ, and T1D-associated visfatin. Contrary, in children diagnosed with exclusively T1D, GAL-1 was positively correlated to CD25hi and CD25hiCD101+ Treg cells. For children with only CeD, no association between GAL-1 and other immune markers was observed. In conclusion, the association observed between GAL-1, soluble immune markers, and Treg cells may indicate a role for GAL-1 in the pathophysiology of T1D and, to some extent, also in CeD.

Hydrodynamic model for renal microvascular filtration: Effects of physiological and hemodynamic changes on glomerular size-selectivity

OBJECTIVE

The first step in renal urine formation is ultrafiltration across the glomerular barrier. The change in its nanostructure has been associated with nephrotic syndromes. Effects of physiological and hemodynamic factor alterations associated with diabetic nephropathy (DN) on glomerular permselectivity are examined through a mathematical model employing low-Reynolds-number hydrodynamics and hindered transport theory.

METHODS

Glomerular capillaries are represented as networks of cylindrical tubes with multilayered walls. Glomerular basement membrane (GBM) is a fibrous medium with bimodal fiber sizes. Epithelial slit fiber spacing follows a lognormal distribution based on reported electron micrographs with the highest resolution. Endothelial fenestrae are filled with fibers the size of glycosaminoglycans (GAGs). Effects of fiber-macromolecule steric and hydrodynamic interactions are included. Focusing on diabetic nephropathy, the physiological and hemodynamic factors employed in the computation are those reported for healthy humans and patients with early-but-overt diabetic nephropathy. The macromolecule concentration is obtained as a finite element solution of the convection-diffusion equation.

RESULTS

Computed sieving coefficients averaged along the capillary length agree well with ficoll sieving coefficients from studies in humans for most solute radii. GBM thickening and the loss of the slit diaphragm hardly affect glomerular permselectivity. GAG volume fraction reduction in the endothelial fenestrae, however, significantly increases macromolecule filtration. Increased renal plasma flow rate (RPF), glomerular hypertension, and reduction of lumen osmotic pressure cause a slight sieving coefficient decrease. These effects are amplified by an increased macromolecule size.

CONCLUSION

Our results indicate that glomerular hypertension and the reduction in the oncotic pressure decreases glomerular macromolecule filtration. Reduction of RPF and changes in the glomerular barrier structure associated with DN, however, increase the solute sieving. Damage to GAGs caused by hyperglycemia is likely to be the most prominent factor affecting glomerular size-selectivity.

Assessment of the Effects of Si Addition to a New TiMoZrTa System

Ti-based alloys are widely used in medical applications. When implant devices are used to reconstruct disordered bone, prevent bone resorption and enhance good bone remodeling, the Young's modulus of implants should be close to that of the bone. To satisfy this requirement, many titanium alloys with different biocompatible elements (Zr, Ta, Mo, Si etc.) interact well with adjacent bone tissues, promoting an adequate osseointegration. Four new different alloys were obtained and investigated regarding their microstructure, mechanical, chemical and biological behavior (in vitro and in vivo evaluation), as follows: Ti₂₀Mo₇Zr₁₅Ta, Ti₂₀Mo₇Zr₁₅Ta_0.5Si, Ti₂₀Mo₇Zr₁₅Ta_0.75Si and Ti₂₀Mo₇Zr₁₅TaSi. 60 days after implantation, both in control and experimental rabbits, at the level of implantation gap and into the periimplant area were found the mesenchymal stem cells which differentiate into osteoblasts, then osteocytes and osteoclasts which are involved in the new bone synthesis and remodeling, the periimplant fibrous capsule being continued by newly spongy bone tissue, showing a good osseointegration of alloys. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay confirmed the in vitro cytocompatibility of the prepared alloys.

Matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases in kidney disease

Matrix metalloproteinases (MMPs) are a group of zinc and calcium endopeptidases which cleave extracellular matrix (ECM) proteins. They are also involved in the degradation of cell surface components and regulate multiple cellular processes, cell to cell interactions, cell proliferation, and cell signaling pathways. MMPs function in close interaction with the endogenous tissue inhibitors of matrix metalloproteinases (TIMPs), both of which regulate cell turnover, modulate various growth factors, and participate in the progression of tissue fibrosis and apoptosis. The multiple roles of MMPs and TIMPs are continuously elucidated in kidney development and repair, as well as in a number of kidney diseases. This chapter focuses on the current findings of the significance of MMPs and TIMPs in a wide range of kidney diseases, whether they result from kidney tissue changes, hemodynamic alterations, tubular epithelial cell apoptosis, inflammation, or fibrosis. In addition, the potential use of these endopeptidases as biomarkers of renal dysfunction and as targets for therapeutic interventions to attenuate kidney disease are also explored in this review.

Aortic Aneurysms, Chronic Kidney Disease and Metalloproteinases

Metalloproteinases (MPs) are proteolytic enzymes involved in extracellular matrix deposition, regulation of cellular signals of inflammation, proliferation, and apoptosis. Metalloproteinases are classified into three families: Matrix-MPs (MMPs), A-Disintegrin-and-Metalloprotease (ADAMs), and the A-Disintegrin-and-Metalloproteinase-with-Thrombospondin-1-like-Domains (ADAMTS). Previous studies showed that MPs are involved in the development of aortic aneurysms (AA) and, concomitantly, in the onset of chronic kidney disease (CKD). CKD has been, per se, associated with an increased risk for AA. The aim of this review is to examine the pathways that may associate MPs with CKD and AA. Several MMPs, such as MMP-2, -8, -9, and TIMP-1 have been shown to damage the AA wall and to have a toxic effect on renal tubular cells, leading to fibrosis. Similarly, ADAM10 and 17 have been shown to degrade collagen in the AA wall and to worsen kidney function via pro-inflammatory stimuli, the impairment of the Renin-Angiotensin-Aldosterone System, and the degradation of structural proteins. Moreover, MMP-2 and -9 inhibitors reduced aneurysm growth and albuminuria in experimental and human studies. It would be important, in the future, to expand research on MPs from both a prognostic, namely, to refine risk stratification in CKD patients, and a predictive perspective, likely to improve prognosis in response to targeted treatments.

The Role of Prognostic and Predictive Biomarkers for Assessing Cardiovascular Risk in Chronic Kidney Disease Patients

Chronic kidney disease (CKD) is currently defined as the presence of proteinuria and/or an eGFR < 60 mL/min/1.73m² on the basis of the renal diagnosis. The global dimension of CKD is relevant, since its prevalence and incidence have doubled in the past three decades worldwide. A major complication that occurs in CKD patients is the development of cardiovascular (CV) disease, being the incidence rate of fatal/nonfatal CV events similar to the rate of ESKD in CKD. Moreover, CKD is a multifactorial disease where multiple mechanisms contribute to the individual prognosis. The correct development of novel biomarkers of CV risk may help clinicians to ameliorate the management of CKD patients. Biomarkers of CV risk in CKD patients are classifiable as prognostic, which help to improve CV risk prediction regardless of treatment, and predictive, which allow the selection of individuals who are likely to respond to a specific treatment. Several prognostic (cystatin C, cardiac troponins, markers of inflammation, and fibrosis) and predictive (genes, metalloproteinases, and complex classifiers) biomarkers have been developed. Despite previous biomarkers providing information on the pathophysiological mechanisms of CV risk in CKD beyond proteinuria and eGFR, only a minority have been adopted in clinical use. This mainly depends on heterogeneous results and lack of validation of biomarkers. The purpose of this review is to present an update on the already assessed biomarkers of CV risk in CKD and examine the strategies for a correct development of biomarkers in clinical practice. Development of both predictive and prognostic biomarkers is an important task for nephrologists. Predictive biomarkers are useful for designing novel clinical trials (enrichment design) and for better understanding of the variability in response to the current available treatments for CV risk. Prognostic biomarkers could help to improve risk stratification and anticipate diagnosis of CV disease, such as heart failure and coronary heart disease.

Suppressed immune profile in children with combined type 1 diabetes and celiac disease

Children diagnosed with a combination of type 1 diabetes (T1D) and celiac disease (CD) show a dysregulated T helper type 1 (Th1)/Th17 response. Besides the cellular involvement, several soluble immune markers are involved in the autoimmune process of both T1D and CD. Only few studies have examined the peripheral pattern of different cytokines, chemokines and acute-phase proteins (APP) in children with combined T1D and CD. To our knowledge, no studies have evaluated the serum levels of adipocytokines and matrix metalloproteinases (MMPs) in this context. The purpose of the present study was to acquire more knowledge and to gain deeper understanding regarding the peripheral immunoregulatory milieu in children with both T1D and CD. The study included children diagnosed with both T1D and CD (n = 18), children with T1D (n = 27) or CD (n = 16) and reference children (n = 42). Sera were collected and analysis of 28 immune markers (cytokines, chemokines, APPs, adipocytokines and MMPs) was performed using the Luminex technique. The major findings showed that children with a double diagnosis had lower serum levels of interleukin (IL)-22, monocyte chemoattractant protein (MIP)-1α, monocyte chemoattractant protein (MCP)-1, procalcitonin, fibrinogen, visfatin and matrix metalloproteinase (MMP)-2. These results indicate a suppressed immune profile in children with combined T1D and CD, including Th17 cytokines, chemokines, APPs, adipocytokines and MMPs. We conclude that, besides cytokines and chemokines, other immune markers, e.g. APPs, adipocytokines and MMPs, are of importance for further investigations to elucidate the heterogeneous immune processes present in patients diagnosed with T1D in combination with CD.

Endothelial glycocalyx restoration by growth factors in diabetic nephropathy

The endothelial glycocalyx (eGlx) constitutes the first barrier to protein in all blood vessels. This is particularly noteworthy in the renal glomerulus, an ultrafiltration barrier. Leakage of protein, such as albumin, across glomerular capillaries results in albumin in the urine (albuminuria). This is a hall mark of kidney disease and can reflect loss of blood vessel integrity in microvascular beds elsewhere. We discuss evidence demonstrating that targeted damage to the glomerular eGlx results in increased glomerular albumin permeability. EGlx is lost in diabetes and experimental models demonstrate loss from glomerular endothelial cells. Vascular endothelial growth factor (VEGF)A is upregulated in early diabetes, which is associated with albuminuria. Treatment with paracrine growth factors such as VEGFC, VEGF165b and angiopoietin-1 can modify VEGFA signalling, rescue albumin permeability and restore glomerular eGlx in models of diabetes. Manipulation of VEGF receptor 2 signalling, or a common eGlx biosynthesis pathway by these growth factors, may protect and restore the eGlx layer. This would help to direct future therapeutics in diabetic nephropathy.

The Association of Matrix Metalloproteinases with Chronic Kidney Disease and Peripheral Vascular Disease: A Light at the End of the Tunnel?

: Chronic Kidney Disease (CKD) represents a risk factor for fatal and nonfatal cardiovascular (CV) events, including peripheral vascular disease (PVD). This occurs because CKD encompasses several factors that lead to poor prognoses, mainly due to a reduction of the estimated glomerular filtration rate (eGFR), the presence of proteinuria, and the uremic inflammatory milieu. The matrix metalloproteinases (MMPs) are a group of zinc-containing endopeptidases implicated in extracellular matrix (ECM) remodeling, a systemic process in tissue homeostasis. MMPs play an important role in cell differentiation, angiogenesis, inflammation, and vascular damage. Our aim was to review the published evidence regarding the association between MMPs, PVD, and CKD to find possible common pathophysiological mechanisms. MMPs favor ECM deposition through the glomeruli, and start the shedding of cellular junctions and epithelial-mesenchymal transition in the renal tubules. MMP-2 and -9 have also been associated with the presence of systemic vascular damage, since they exert a pro-inflammatory and proatherosclerotic actions. An imbalance of MMPs was found in the context of PVD, where MMPs are predictors of poor prognoses in patients who underwent lower extremity revascularization. MMP circulating levels are increased in both conditions, i.e., that of CKD and PVD. A possible pathogenic link between these conditions is represented by the enhanced production of transforming growth factor-β that worsens vascular calcifications and atherosclerosis and the development of proteinuria in patients with increased levels of MMPs. Proteinuria has been recognized as a marker of systemic vascular damage, and this may explain in part the increase in CV risk that is manifest in patients with CKD and PVD. In conclusion, MMPs can be considered a useful tool by which to stratify CV risk in patients with CKD and PVD. Further studies are needed to investigate the causal-relationships between MMPs, CKD, and PVD, and to optimize their prognostic and predictive (in response to treatments) roles.

Naringenin ameliorates diabetic neuropathic pain by modulation of oxidative-nitrosative stress, cytokines and MMP-9 levels

Diabetes mellitus is a serious debilitating epidemic affecting all social strata, imposing huge health, social and economic burdens.

Updating the role of matrix metalloproteinases in mineralized tissue and related diseases

Bone development and healing processes involve a complex cascade of biological events requiring well-orchestrated synergism with bone cells, growth factors, and other trophic signaling molecules and cellular structures. Beyond health processes, MMPs play several key roles in the installation of heart and blood vessel related diseases and cancer, ranging from accelerating metastatic cells to ectopic vascular mineralization by smooth muscle cells in complementary manner. The tissue inhibitors of MMPs (TIMPs) have an important role in controlling proteolysis. Paired with the post-transcriptional efficiency of specific miRNAs, they modulate MMP performance. If druggable, these molecules are suggested to be a platform for development of "smart" medications and further clinical trials. Thus, considering the pleiotropic effect of MMPs on mammals, the purpose of this review is to update the role of those multifaceted proteases in mineralized tissues in health, such as bone, and pathophysiological disorders, such as ectopic vascular calcification and cancer.

Matrix Metalloproteinases in Renal Diseases: A Critical Appraisal

Matrix metalloproteinases (MMPs) are endopeptidases within the metzincin protein family that not only cleave extracellular matrix (ECM) components, but also process the non-ECM molecules, including various growth factors and their binding proteins. MMPs participate in cell to ECM interactions, and MMPs are known to be involved in cell proliferation mechanisms and most probably apoptosis. These proteinases are grouped into six classes: collagenases, gelatinases, stromelysins, matrilysins, membrane type MMPs, and other MMPs. Various mechanisms regulate the activity of MMPs, inhibition by tissue inhibitors of metalloproteinases being the most important. In the kidney, intrinsic glomerular cells and tubular epithelial cells synthesize several MMPs. The measurement of circulating MMPs can provide valuable information in patients with kidney diseases. They play an important role in many renal diseases, both acute and chronic. This review attempts to summarize the current knowledge of MMPs in the kidney and discusses recent data from patient and animal studies with reference to specific diseases. A better understanding of the MMPs' role in renal remodeling may open the way to new interventions favoring deleterious renal changes in a number of kidney diseases.

MMP targeting in the battle for vision: Recent developments and future prospects in the treatment of diabetic retinopathy

Matrix metalloproteinases (MMPs) are enzymes capable of degrading nearly all types of extracellular matrix. They perform a wide range of roles in physiological processes, which is the reason for their strict regulation by numerous mechanisms including natural tissue inhibitors of metalloproteinases (TIMP). Research only started to shed light on more troublesome aspects of MMPs function, like cancer progression, Alzheimer's disease, atherosclerosis, ageing. Moreover, their profound role in diabetes is being carefully investigated including one of its most debilitating complications - diabetic retinopathy (DR), the leading cause of acquired blindness worldwide. Traditional treatment of this condition seems to be only mildly satisfactory, which elicited substantial interest in the field of new therapeutic methods including MMP targeting. So far, significant roles of MMP-2 and MMP-9 in the development of retinopathy have been established, with special attention given to the process of blood-retinal barrier impairment. Further exploration revealed MMP-10 and MMP-14 involvement as well as changes in MMP/TIMP ratio. In this review, we provide insight into MMPs role in diabetic retinopathy with a clarification of various mechanisms regulating MMP activity in the light of the recent studies. We conclude with an overview of novel DR therapies targeting MMPs and point to the need of further examination of their usefulness in clinical setting, with an eye towards future research.

Outcome of patients with and poor prognostic factors for Mycobacterium kansasii-pulmonary disease

BACKGROUND

Aggressive therapy for Mycobacterium kansasii-pulmonary disease (MK-PD) is recommended because of the virulence of MK. However, some clinicians may be concerned regarding the lengthy course and numerous adverse effects. This study evaluated the natural course of MK-PD and investigated its prognostic factors.

METHODS

Radiographic outcome, prognostic factors, and mortality within 1 year for MK-PD were obtained from patients in 6 hospitals in Taiwan from 2010 to 2014 (derivation cohort) and validated using patients in 2015 and 2016 (validation cohort).

RESULTS

Of the 109 patients with MK-PD in the derivation cohort, radiographic progression occurred in 70 (64%), with a 1-year mortality rate of 43% and median survival of 71 days, whereas none of the 39 cases without radiographic progression died. All patients with acid-fast smear (AFS) grade ≥ 3 experienced radiographic progression. For the others, the independent risk factors of radiographic progression were fibroCavitary pattern, Leucocyte count >9000/μL, Old age (age >65 years), pUre MK in sputum (no other mycobacteria), and no Diabetes mellitus (the CLOUD factors). By applying these criteria to the validation cohort (n = 112), 3 (9%) of the 33 patients with MK-PD who initially had AFS grade < 3 and < 3 CLOUD risk factors experienced radiographic progression, and none of the 3 died of MK-PD.

CONCLUSIONS

Because of the high risk of radiographic progression and subsequent fatal outcome, immediate anti-MK treatment is recommended. For patients with MK-PD who have sputum AFS grade <3 and < 3 CLOUD risk factors, regular follow-up may be an alternative.

Regulation of MMP 2 and MMP 9 expressions modulated by AP-1 (c-jun) in wound healing: improving role of Lucilia sericata in diabetic rats

AIMS

Lucilia sericata larvae have been successfully used on healing of wounds in the diabetics. However, the involvement of the extraction/secretion (ES) products of larvae in the treatment of diabetic wounds is still unknown. Activator protein-1 (AP-1) transcription, composed of c-jun and c-Fos proteins, has been shown to be the principal regulator of multiple MMP transcriptions under a variety of conditions, also in diabetic wounds. Specifically, MMP-2 and MMP-9's transcriptions are known to be modulated by AP-1. c-jun has been demonstrated to be a repressor of p53 in immortalized fibroblasts. The aim of the present study is to investigate the effects of L. sericata ES on the expression of AP-1 (c-jun), p53, MMP-2, and MMP-9 in wound biopsies dissected from streptozotocin induced diabetic rats.

METHODS

The expression levels of MMP-2, MMP-9, c-jun and p53 in dermal tissues were determined at days 0, 3, 7 and 14 after wounding, using immunohistochemical analysis and quantitative real-time PCR.

RESULTS

The treatment with ES significantly decreased through inflammation-based induction of MMP-2 and MMP-9 expression levels in the wounds of diabetic groups, compared to control groups at the third day of wound healing. At the 14th day, there were dramatic decreases in expression of c-jun, MMP-9, and p53 in ES-treated groups, compared to the diabetic group (P < 0.001, P < 0.05 and P < 0.01, respectively).

CONCLUSION

ES products of L. sericata may enhance the process of wound healing in phases of inflammation, proliferation, and re-epithelization, essentially via regulating c-jun expression and modulating MMP-2 and MMP-9 expressions.

Dehydrated Amnion/Chorion Improves Achilles Tendon Repair in a Diabetic Animal Model

INTRODUCTION

Healing of tendon injuries is often plagued by significant scar formation and compromised biomechanical function. For those with diabetes, these injuries are further complicated by alterations to the extracellular matrix of the tendon, poor circulation, and delayed wound healing; consequently, complications and re-rupture rates for patients with diabetes are reported higher than the typical patient population. Placental derived membranes, specifically dehydrated human amnion/chorion membranes (dACMs), have been utilized clinically as an adhesion barrier, and these membranes have been shown to reduce scarring and aid in tissue repair.

OBJECTIVE

The purpose of this study was to evaluate the effect of dACMs on tendon repair in a diabetic model with impaired healing.

MATERIALS AND METHODS

Using a type II diabetic model (BBZDR/WOR rats), a full-thickness injury was made through the Achilles tendon and repaired using a modified Kessler method. Repaired tendons were wrapped with dACM or left unwrapped as a control (n = 15/group; n = 30 total). Tendons were retrieved at 14 (n = 5/group; n = 10 total) or 28 days (n = 10/group; n = 20 total) and evaluated using histology, immunofluorescence, and biomechanical testing.

RESULTS

Treatment of tendons with dACM resulted in reduced failure rates, increased cell migration, and improved mechanical properties (compared with unwrapped controls). The dACM-treated tendons also showed changes in the production of several important biomarkers to tendon healing at both 14 and 28 days; most notably, Scleraxis was found to be upregulated in dACM-treated tendons.

CONCLUSIONS

This study highlights a promising treatment option for this challenging clinical population.

Cell Adhesion Molecules are Mediated by Photobiomodulation at 660 nm in Diabetic Wounded Fibroblast Cells

Diabetes affects extracellular matrix (ECM) metabolism, contributing to delayed wound healing and lower limb amputation. Application of light (photobiomodulation, PBM) has been shown to improve wound healing. This study aimed to evaluate the influence of PBM on cell adhesion molecules (CAMs) in diabetic wound healing. Isolated human skin fibroblasts were grouped into a diabetic wounded model. A diode laser at 660 nm with a fluence of 5 J/cm² was used for irradiation and cells were analysed 48 h post-irradiation. Controls consisted of sham-irradiated (0 J/cm²) cells. Real-time reverse transcription (RT) quantitative polymerase chain reaction (qPCR) was used to determine the expression of CAM-related genes. Ten genes were up-regulated in diabetic wounded cells, while 25 genes were down-regulated. Genes were related to transmembrane molecules, cell–cell adhesion, and cell–matrix adhesion, and also included genes related to other CAM molecules. PBM at 660 nm modulated gene expression of various CAMs contributing to the increased healing seen in clinical practice. There is a need for new therapies to improve diabetic wound healing. The application of PBM alongside other clinical therapies may be very beneficial in treatment.

Metalloproteinase Changes in Diabetes

Matrix metalloproteinases (MMPs) constitute a group of over 20 structurally-related proteins which include a Zn(++) ion binding site that is essential for their proteolytic activities. These enzymes play important role in extracellular matrix turnover in order to maintain a proper balance in its synthesis and degradation. MMPs are associated to several physiological and pathophysiological processes, including diabetes mellitus (DM). The mechanisms of DM and its complications is subject of intense research and evidence suggests that MMPs are implicated with the development and progression of diabetic microvascular complications such as nephropathy, cardiomyopathy, retinopathy and peripheral neuropathy. Recent data has associated DM to changes in the tendon structure, including abnormalities in fiber structure and organization, increased tendon thickness, volume and disorganization obtained by image and a tendency of impairing biomechanical properties. Although not fully elucidated, it is believed that DM-induced MMP dysregulation may contribute to structural and biomechanical alterations and impaired process of tendon healing.

KATP channels in high glucose-induced rat mesangial cell proliferation and release of MMP-2 and fibronectin

ATP-sensitive potassium (KATP) channels are well characterized in cardiac, pancreatic and many other muscle cells. The purpose of this study was to determine if KATP channels play a role in diabetic nephropathy (DN). In the present study, functional expression of the KATP channel was examined in rat mesangial cells with or without high glucose (HG) stimulation. The mesangial cell proliferation and the release of matrix metalloproteinase (MMP)-2 and fibronectin in response to high glucose with a selective opener of KATP (diazoxide, DZX), or with a selective inhibitor of KATP (5-hydroxydecanoate, 5-HD) were also measured. The cell proliferation was observed using Cell Counting Kit-8 assay, and the mRNA expressions of KATP subunit, including Kir6.1, Kir6.2, sulfonylurea receptor 1 (SUR1), SUR2A and SUR2B, were assessed using quantitative real-time PCR. MMP-2 and fibronectin release was measured by ELISA. The present study clarified expression of SUR subunit of KATP in plasma. HG treatment could cause increased cell proliferation and release of MMP-2 and fibronectin in a dose-dependent manner. HG also significantly decreased the expression of Kir6.1, SUR2A and SUR2B. Pretreatment of DZX markedly decreased the expression of SUR1, SUR2A and SUR2B, but had no effect on Kir6.1 expression compared with HG alone, while these changes were inhibited by 5-HD pretreatment. Moreover, DZX also inhibited cell proliferation and release of MMP-2 and fibronectin in HG-induced rat mesangial cells, and that was corrected by 5-HD. These data suggest that HG stimulates mesangial cell proliferation and cellular matrix release via inhibiting KATP channel activity, leading us to propose that KATP channel dysfunction may be involved in the development of DN.

Increased levels of inflammatory mediators and proinflammatory monocytes in patients with type I diabetes mellitus and nephropathy

AIMS

To investigate and describe the relationship between diabetic nephropathy and systemic inflammation in patients with type 1 diabetes mellitus (T1DM).

METHODS

Patients with T1DM, with or without reduced renal function due to diabetic nephropathy, were included. Differences in inflammatory mediators, adhesion molecules, markers of endothelial dysfunction and subsets of monocytes were studied in patients with mean disease duration of 31years.

RESULTS

Patients with T1DM with and without renal failure were compared. Patients with nephropathy had increased plasma levels of proinflammatory monocytes, as well as circulatory PAI-1, syndecan-1, VEGF, IL-1β, IL-1Ra and CCL4. Peripheral blood mononuclear cells from patients with nephropathy numerically increased soluble ICAM and PAI-1 in co-culture with primary endothelial cells compared to cells from patients without nephropathy.

CONCLUSIONS

T1DM patients with kidney failure have higher levels of proinflammatory monocytes and circulatory inflammatory mediators compared to patients with T1DM alone. The results highlight the importance of inflammation and endothelial dysfunction in diabetic nephropathy with reduced GFR.

Diabetic nephropathy: A potential savior with 'rotten-egg' smell

Diabetic nephropathy (DN) is currently the leading cause of end-stage renal disease. Despite optimal management, DN is still a major contributor to morbidity and mortality of diabetic patients worldwide. The major pathological alterations in DN include excessive accumulation and deposition of extracellular matrix, leading to expansion of mesangial matrix, thickening of glomerular basement membrane and tubulointerstitial fibrosis. At the molecular level, accumulating evidence suggests that hyperglycemia or high glucose mediates renal injury in DN via multiple molecular mechanisms such as induction of oxidative stress, upregulation of renal transforming growth factor beta-1 expression, production of proinflammatory cytokines, activation of fibroblasts and renin angiotensin system, and depletion of adenosine triphosphate. Also worrying is the fact that existing therapies only retard the disease progression but do not prevent it. Therefore, there is urgent need to identify novel therapies to target additional disease mechanisms. Hydrogen sulfide (H₂S), the third member of the gasotransmitter family, has recently been identified and demonstrated to possess important therapeutic characteristics that prevent the development and progression of DN in experimental animals by targeting several important molecular pathways, and therefore may represent an alternative or additional therapeutic approach for DN. This review discusses recent experimental findings on the molecular mechanisms underlying the therapeutic effects of H₂S against the development and progression of DN and its clinical application in the future.

GJB2, SLC26A4, and mitochondrial DNA12S rRNA hot-spots in 156 subjects with non-syndromic hearing loss in Tengzhou, China

CONCLUSION

In this cohort of 156 non-syndromic hearing-impaired subjects of Tengzhou area, the most common deafness-associated genes GJB2, SLC26A4 and mtDNA 12S rRNA were investigated by SNPscan efficiently. GJB2 c.235delC and SLC26A4 c.IVS7-2A > G were the most common mutation sites.

OBJECTIVES

Until now, there is no systematic gentic analysis in patients with non-syndromic hearing loss for Tengzhou area, so we evaluated the molecular etiology to investigate the hot-sports.

METHODS

Peripheral blood samples were obtained from 156 patients with severe-to-profound non-syndromic deafness in Tengzhou. The SNP scan assay technique was performed for a rapid multiplex genetic screening to detect the 115 mutations of the most common three genes. All results were statistically analyzed with SPSS software.

RESULTS

Among the 156 analyzed patients, 60 patients were demonstrated with deafness genes, accounting for 38.46% (60/156), including GJB2 (22.44%, 35/156), SLC26A4 (13.66%, 22/156), and mtDNA 12S rRNA (2.56%, 4/156). In this study, we confirmed 23 deafness-causing mutations and 27 different allelic combinations including GJB2 (eight variants, 11 allelic combinations), SLC26A4 (13 variants, 16 allelic combinations) and mtDNA 12S rRNA (two variants). The occurrence rates of these deafness-causing mutations GJB2 c.235delC and SLC26A4 c.IVS7-2A > G were significantly higher than other mutation sites (p < 0.01).

Matrix Metalloproteinase-1 and Matrix Metalloproteinase-9 in the Aqueous Humor of Diabetic Macular Edema Patients

Purpose

To assess the concentrations of matrix metalloproteinase (MMP)-1 and MMP-9 in the aqueous humor of diabetic macular edema (DME) patients.

Method

The concentrations of MMP-1 and MMP-9 in the aqueous humors of 15 cataract patients and 25 DME patients were compared. DME patients were analyzed according to the diabetic retinopathy (DR) stage, diabetes mellitus (DM) duration, pan-retinal photocoagulation (PRP) treatment, recurrence within 3 months, HbA1C (glycated hemoglobin) level, and axial length.

Results

The concentrations of MMP-1 and MMP-9 of the DME groups were higher than those of the control group (p = 0.005 and p = 0.002, respectively). There was a significant difference in MMP-1 concentration between the mild non-proliferative diabetic retinopathy (NPDR) group and the proliferative diabetic retinopathy (PDR) group (p = 0.012). MMP-1 concentrations were elevated in PRP-treated patients (p = 0.005). There was a significant difference in MMP-9 concentrations between the mild NPDR group and the PDR group (p < 0.001), and between the moderate and severe NPDR group and the PDR group (p < 0.001). The MMP-9 concentrations in PRP treated patients, DM patients with diabetes ≥ 10 years and recurrent DME within 3months were elevated (p = 0.023, p = 0.011, and p = 0.027, respectively). In correlation analyses, the MMP-1 level showed a significant correlation with age (r = -0.48, p = 0.01,), and the MMP-9 level showed significant correlations with axial length (r = -0.59, p < 0.01) and DM duration (r = 049, p = 0.01).

Conclusions

Concentrations of MMP-1 and MMP-9 were higher in the DME groups than in the control group. MMP-9 concentrations also differed depending on DR staging, DM duration, PRP treatment, and degree of axial myopia. MMP-9 may be more important than MMP-1 in the induction of DM complications in eyes.

The Role of Matrix Metalloproteinases in Diabetic Wound Healing in relation to Photobiomodulation

The integration of several cellular responses initiates the process of wound healing. Matrix Metalloproteinases (MMPs) play an integral role in wound healing. Their main function is degradation, by removal of damaged extracellular matrix (ECM) during the inflammatory phase, breakdown of the capillary basement membrane for angiogenesis and cell migration during the proliferation phase, and contraction and remodelling of tissue in the remodelling phase. For effective healing to occur, all wounds require a certain amount of these enzymes, which on the contrary could be very damaging at high concentrations causing excessive degradation and impaired wound healing. The imbalance in MMPs may increase the chronicity of a wound, a familiar problem seen in diabetic patients. The association of diabetes with impaired wound healing and other vascular complications is a serious public health issue. These may eventually lead to chronic foot ulcers and amputation. Low intensity laser irradiation (LILI) or photobiomodulation (PBM) is known to stimulate several wound healing processes; however, its role in matrix proteins and diabetic wound healing has not been fully investigated. This review focuses on the role of MMPs in diabetic wound healing and their interaction in PBM.

Decreases in plasma MMP-2/TIMP-2 and MMP-9/TIMP-1 ratios in uremic patients during hemodialysis

BACKGROUND

Matrix metalloproteinases (MMPs) and their endogenous tissue inhibitors (TIMPs) play important roles in the pathophysiology of renal diseases. Imbalanced MMPs/TIMPs are implicated in the vascular alterations of uremic patients on hemodialysis (HD). We have investigated the plasma levels of MMP-2, MMP-9, TIMP-1 and TIMP-2 in uremic patients and the effects of a course of HD on the changes in these factors.

METHODS

There were 382 uremic patients on regular HD treatment and 50 healthy controls enrolled in this study. The plasma MMP-2 and MMP-9 levels were detected by gelatin zymography, and TIMP-1 and TIMP-2 concentrations were determined by ELISA assay.

RESULTS

Significantly higher plasma MMP-2 and MMP-9 and decreased TIMP-1 in the uremic patients were detected compared with those in the controls. Therefore, there were markedly higher MMP-2/TIMP-2 and MMP-9/TIMP-1 ratios in the uremic patients. In the course of a single HD session, the plasma MMP-2 level was significantly decreased from pre-HD to post-HD. TIMP-1 concentration was significantly increased from pre-HD to post-HD. Although the HD session did not have a significant effect on the levels of plasma MMP-9 and TIMP-2, both plasma MMP-2/TIMP-2 and MMP-9/TIMP-1 ratios were significantly decreased from pre-HD to post-HD levels.

CONCLUSION

HD session could decrease MMP-2 and increase TIMP-1 level in the circulation of uremic patients. The physiological significance of reduced MMPs/TIMPs ratio due to a single HD session is required to further validate.

Serglycin in Quiescent and Proliferating Primary Endothelial Cells

Proteoglycans are fundamental components of the endothelial barrier, but the functions of the proteoglycan serglycin in endothelium are less described. Our aim was to describe the roles of serglycin in processes relevant for endothelial dysfunction. Primary human umbilical vein endothelial cells (HUVEC) were cultured in vitro and the expression of proteoglycans was investigated. Dense cell cultures representing the quiescent endothelium coating the vasculature was compared to sparse activated cell cultures, relevant for diabetes, cancer and cardiovascular disease. Secretion of 35S- proteoglycans increased in sparse cultures, and we showed that serglycin is a major component of the cell-density sensitive proteoglycan population. In contrast to the other proteoglycans, serglycin expression and secretion was higher in proliferating compared to quiescent HUVEC. RNAi silencing of serglycin inhibited proliferation and wound healing, and serglycin expression and secretion was augmented by hypoxia, mechanical strain and IL-1β induced inflammation. Notably, the secretion of the angiogenic chemokine CCL2 resulting from IL-1β activation, was increased in serglycin knockdown cells, while angiopoietin was not affected. Both serglycin and CCL2 were secreted predominantly to the apical side of polarized HUVEC, and serglycin and CCL2 co-localized both in perinuclear areas and in vesicles. These results suggest functions for serglycin in endothelial cells trough interactions with partner molecules, in biological processes with relevance for diabetic complications, cardiovascular disease and cancer development.

A glimpse of matrix metalloproteinases in diabetic nephropathy

Matrix metalloproteinases (MMPs) are proteolytic enzymes belonging to the family of zinc-dependent endopeptidases that are capable of degrading almost all the proteinaceous components of the extracellular matrix (ECM). It is known that MMPs play a role in a number of renal diseases, such as, various forms of glomerulonephritis and tubular diseases, including some of the inherited kidney diseases. In this regard, ECM accumulation is considered to be a hallmark morphologic finding of diabetic nephropathy, which not only is related to the excessive synthesis of matrix proteins, but also to their decreased degradation by the MMPs. In recent years, increasing evidence suggest that there is a good correlation between the activity or expression of MMPs and progression of renal disease in patients with diabetic nephropathy and in various experimental animal models. In such a diabetic milieu, the expression of MMPs is modulated by high glucose, advanced glycation end products (AGEs), TGF-β, reactive oxygen species (ROS), transcription factors and some of the microRNAs. In this review, we focused on the structure and functions of MMPs, and their role in the pathogenesis of diabetic nephropathy.

Plasma levels of matrix metalloproteinase-2, -3, -10, and tissue inhibitor of metalloproteinase-1 are associated with vascular complications in patients with type 1 diabetes: the EURODIAB Prospective Complications Study

BACKGROUND

Impaired regulation of extracellular matrix remodeling by matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinase (TIMP) may contribute to vascular complications in patients with type 1 diabetes. We investigated associations between plasma MMP-1, -2, -3, -9, -10 and TIMP-1, and cardiovascular disease (CVD) or microvascular complications in type 1 diabetic patients. We also evaluated to which extent these associations could be explained by low-grade inflammation (LGI) or endothelial dysfunction (ED).

METHODS

493 type 1 diabetes patients (39.5 ± 9.9 years old, 51% men) from the EURODIAB Prospective Complications Study were included. Linear regression analysis was applied to investigate differences in plasma levels of MMP-1, -2, -3, -9, -10, and TIMP-1 between patients with and without CVD, albuminuria or retinopathy. All analyses were adjusted for age, sex, duration of diabetes, Hba1c and additionally for other cardiovascular risk factors including LGI and ED.

RESULTS

Patients with CVD (n = 118) showed significantly higher levels of TIMP-1 [β = 0.32 SD (95%CI: 0.12; 0.52)], but not of MMPs, than patients without CVD (n = 375). Higher plasma levels of MMP-2, MMP-3, MMP-10 and TIMP-1 were associated with higher levels of albuminuria (p-trends were 0.028, 0.004, 0.005 and 0.001, respectively). Severity of retinopathy was significantly associated with higher levels of MMP-2 (p-trend = 0.017). These associations remained significant after further adjustment for markers of LGI and ED.

CONCLUSIONS

These data support the hypothesis that impaired regulation of matrix remodeling by actions of MMP-2, -3 and-10 and TIMP-1 contributes to the pathogenesis of vascular complications in type 1 diabetes.

MMP-9- and NMDA receptor-mediated mechanism of diabetic renovascular remodeling and kidney dysfunction: hydrogen sulfide is a key modulator

Previously we reported that matrix metalloproteinase-9 (MMP-9) plays an important role in extracellular matrix (ECM) remodeling in diabetic kidney. Induction of NMDA-R and dysregulation of connexins (Cxs) were also observed. We concluded that this was due to decreased H2S production by downregulation of CBS and CSE enzymes. However, the potential role of H2S to mitigate ECM dysregulation and renal dysfunction was not clearly understood. The present study was undertaken to determine whether H2S supplementation reduces MMP-9-induced ECM remodeling and dysfunction in diabetic kidney. Wild type (C57BL/6J), diabetic (Akita, C57BL/6J-Ins2(Akita)), MMP-9 knockout (MMP-9(-/-), M9KO) and double KO of Akita/MMP-9(-/-) (DKO) mice were treated without or with 0.005 g/l of NaHS (as a source of H2S) in drinking water for 30 days. Decreased tissue production and plasma content of H2S in Akita mice were ameliorated with H2S supplementation. Dysregulated expression of MMP-9, CBS, CSE, NMDA-R1 and Cxs-40, -43 was also normalized in Akita mice treated with H2S. In addition, increased renovascular resistive index (RI), ECM deposition, plasma creatinine, and diminished renal vascular density and cortical blood flow in Akita mice were normalized with H2S treatment. We conclude that diminished H2S production in renal tissue and plasma levels in diabetes mediates adverse renal remodeling, and H2S therapy improves renal function through MMP-9- and NMDA-R1-mediated pathway.

Biofluid proteases profiling in diabetes mellitus

The investigation of protease relevance in biologic systems beyond catabolism of proteins and peptides to amino acids has stimulated interest as to their role in the pathogenesis of several disorders including diabetes mellitus (DM). Evaluation of proteases and the assessment of their activity in biofluids are fundamental to elucidate these proteolytic systems in DM and its related complications. In contrast to traditional immunoassay or substrate based approaches that targeted specific proteases and their inhibitors, the field of degradomics has provided a comprehensive approach to study these enzymes. Although the degradome contains over 500 proteases, very few have been associated with DM and its micro- and macrovascular complications. In this paper, we review these proteases and their respective inhibitors with emphasis on DM. It is likely that future research will expand these initial studies and look to develop high throughput automated technologies to identify and characterize biofluid proteases of diagnostic and prognostic value in other pathologies.

Association of endothelin-1 and matrix metallopeptidase-9 with metabolic syndrome in middle-aged and older adults

BACKGROUND

Metabolic syndrome (MetS) contains a cluster of cardiovascular risk factors. People with MetS are more susceptible to cardiovascular disease, diabetes mellitus, and cancer. Endothelin-1 (ET-1) and matrix metallopeptidase-9 (MMP-9) have been implicated in the development of cardiovascular diseases, diabetes mellitus and cancers. This cross-sectional study aimed to examine the association of ET-1 and MMP-9 with MetS in middle-aged and older Hong Kong Chinese adults.

METHODS

149 adults aged 50 to 92 (n = 75 for non-MetS group and n = 74 for MetS group) were examined. All subjects were screened for MetS according to the diagnostic guideline of the United States National Cholesterol Education Program (NCEP) Expert Panel Adult Treatment Panel (ATP) III criteria. Serum levels of ET-1 and MMP-9 were measured. Independent t test was used to detect differences between non-MetS and MetS groups and between subjects with or without certain metabolic abnormality. The association of the serum concentration of MMP-9 and ET-1 with MetS parameters were examined by Pearson's correlation analysis.

RESULTS

Serum level of ET-1 is higher in MetS-positive subjects and in subjects with high blood pressure, elevated fasting blood glucose, and central obesity. The serum concentration of MMP-9 is higher in subjects positively diagnosed with MetS and subjects with high blood pressure, elevated fasting blood glucose, low blood high-density lipoprotein-cholesterol (HDL-C), high blood triglycerides, and central obesity. Correlation analyses revealed that serum concentration of ET-1 is positively correlated to systolic blood pressure, waist circumference, fasting blood glucose, and age whereas it is negatively correlated to HDL-C. MMP-9 is positively correlated to systolic blood pressure, waist circumference, fasting blood glucose, and age whereas it is negatively correlated to HDL-C.

CONCLUSION

Serum ET-1 is higher in subjects with hypertension, hyperglycemia, central obesity or MetS. Serum MMP-9 is higher in subjects diagnosed with MetS or having either one of the MetS parameters. Both circulating levels of ET-1 and MMP-9 are correlated to systolic blood pressure, waist circumference, fasting blood glucose, HDL-C, and age. Further research is needed to fully dissect the role of ET-1 and MMP-9 in the development of cancers, diabetes and cardiovascular disease in relation to MetS.

Matrix metalloproteinase 9-mediated shedding of syndecan 4 in response to tumor necrosis factor α: a contributor to endothelial cell glycocalyx dysfunction

The endothelial surface glycocalyx is a hydrated mesh in which proteoglycans are prominent. It is damaged in diseases associated with elevated levels of tumor necrosis factor α (TNF-α). We investigated the mechanism of TNF-α-induced disruption of the glomerular endothelial glycocalyx. We used conditionally immortalized human glomerular endothelial cells (GEnCs), quantitative PCR arrays, Western blotting, immunoprecipitation, immunofluorescence, and dot blots to examine the effects of TNF-α. TNF-α induced syndecan 4 (SDC4) mRNA up-regulation by 2.5-fold, whereas cell surface SDC4 and heparan sulfate (HS) were reduced by 36 and 30%, respectively, and SDC4 and sulfated glycosaminoglycan in the culture medium were increased by 52 and 65%, respectively, indicating TNF-α-induced shedding. Small interfering (siRNA) knockdown of SDC4 (by 52%) caused a corresponding loss of cell surface HS of similar magnitude (38%), and immunoprecipitation demonstrated that SDC4 and HS are shed as intact proteoglycan ectodomains. All of the effects of TNF-α on SDC4 and HS were abrogated by the metalloproteinase (MMP) inhibitor batimastat. Also abrogated was the associated 37% increase in albumin passage across GEnC monolayers. Specific MMP9 knockdown by siRNA similarly blocked TNF-α effects. SDC4 is the predominant HS proteoglycan in the GEnC glycocalyx. TNF-α-induced MMP9-mediated shedding of SDC4 is likely to contribute to the endothelial glycocalyx disruption observed in diabetes and inflammatory states.

Matrix metalloproteinases: potential therapeutic target for diabetic neuropathic pain

INTRODUCTION

MMPs are zinc-dependent endopeptidases that play a key role in the remodeling of extracellular matrix (ECM). Various pathogenic mediators trigger abnormal MMP activity that leads to ECM abnormality. Hyperglycemia is one of the strong stimuli among oxidative stress and inflammation that upregulate MMP expression in the central and peripheral nervous system. MMP-mediated ECM abnormality hypersensitizes peripheral as well as central nerves that precipitate neuropathic pain in diabetic patients.

AREAS COVERED

Molecular mechanisms associated with MMP-mediated diabetic neuropathic pain have been discussed. Various endogenous, natural and synthetic MMP inhibitors are also explored.

EXPERT OPINION

In diabetes, hyperglycemia activates MMPs that along with the other pathogenic mediators cause neuronal injury and precipitates neuropathic pain. Thus, MMPs play a crucial role in the development of neuropathic pain among diabetics. However, MMPs are not only responsible for deleterious ECM abnormalities but are also required for beneficial remodeling of ECM under normal physiological conditions. Therefore, highly selective and specific inhibitors must be designed and explored for their clinical potential for treatment/prevention of diabetic neuropathic pain.

Effects of maternal diabetes on male offspring: high cell proliferation and increased activity of MMP-2 in the ventral prostate

This study presents a comprehensive view of the histological and functional status of the prostate of adult rat offspring of mothers subjected to gestational diabetes induced by alloxan. The ventral prostate of male adult offspring of diabetic (DP) or normal (CP) mothers was evaluated for collagen fibres, cell death, fibroblasts, smooth muscle cells, cell proliferation, matrix metalloproteinases (MMPs), androgen receptors (AR), transforming growth factor β1 (TGFβ-1), catalase and total antioxidant activity. The prostates of DP animals were lower in weight than those of the CP group. The DP group also exhibited hyperglycaemia and hypotestosteronemia, higher cell proliferation and AR expression, a reduction in α-actin (possibly interfering with the reproductive function of the prostate), and enhanced activity of MMP-2, although the absolute content of MMP-2 was lower in this group. These findings were associated with increased TGFβ-1 and decreased collagen distribution. The prostates of DP rats additionally exhibited reductions in catalase and total antioxidant activity. Thus, rats developing in a diabetic intrauterine environment have glycaemic and hormonal changes that impact on the structure and physiology of the prostate in adulthood. The increased AR expression possibly leads to elevated cell proliferation. Stromal remodelling was characterized by enhanced activity of MMP-2 and collagen degradation, even with increased TGFβ-1 activation. These changes associated with increased oxidative stress might interfere with tissue architecture and glandular homeostasis.

Matrix metalloproteinase-9 deficiency attenuates diabetic nephropathy by modulation of podocyte functions and dedifferentiation

Diabetic nephropathy is characterized by excessive deposition of extracellular matrix protein and disruption of the glomerular filtration barrier. Matrix metalloproteinases (MMPs) affect the breakdown and turnover of extracellular matrix protein, suggesting that altered expression of MMPs may contribute to diabetic nephropathy. Here we used an MMP-9 gene knockout mouse model, with in vitro experiments and clinical samples, to determine the possible role of MMP-9 in diabetic nephropathy. After 6 months of streptozotocin-induced diabetes, mice developed markedly increased albuminuria, glomerular and kidney hypertrophy, and thickening of the glomerular basement membrane. Gelatin zymographic analysis and western blotting showed that there was enhanced MMP-9 protein production and activity in the glomeruli. However, MMP-9 knockout in diabetic mice significantly attenuated these nephropathy changes. In cultured podocytes, various cytokines related to diabetic nephropathy including TGF-β1, TNF-α, and VEGF stimulated MMP-9 secretion. Overexpression of endogenous MMP-9 induced podocyte dedifferentiation. MMP-9 also interrupted podocyte cell integrity, promoted podocyte monolayer permeability to albumin, and extracellular matrix protein synthesis. In diabetic patients, the upregulation of urinary MMP-9 concentrations occurred earlier than the onset of microalbuminuria. Thus, MMP-9 seems to play a role in the development of diabetic nephropathy.

Differential effects of Smad3 targeting in a murine model of chronic kidney disease

Transforming growth factor (TGF)‐β1 has a pivotal role in the pathogenesis of progressive kidney diseases that are characterized by fibrosis. The main intracellular signaling pathway of TGF‐β1 is the Smad system, where Smad2 and Smad3 play a central role in transcriptional regulation of target genes involved in extracellular matrix (ECM) metabolism. This study analyzes the hypothesis that blockade of Smad3 attenuates the development of TGF‐β1‐driven renal fibrosis. This was examined in vivo in a transgenic model of TGF‐β1‐induced chronic kidney disease with Smad3 or without Smad3 expression and in vitro in mesangial cells and glomerular endothelial cells with Smad2/3 inhibitors or Smad3‐knockdown. Electron microscopy was used for evaluation of morphological changes, real‐time polymerase chain reaction for detection of RNA expression, and immunohistochemistry for localization of ECM components. Matrix metalloproteinase (MMP) level was assessed by gelatin zymography electrophoresis and located by in situ zymography. The results show TGF‐β1‐induced mesangial matrix expansion, tubulointerstitial fibrosis, and tubular basement membrane thickening that are attenuated by Smad3 deletion, whereas TGF‐β1‐induced glomerular basement membrane thickening is not shown. The amount and distribution profile of MMP‐2 may suggest a role of the enzyme herein. We conclude that Smad3 targeting is not exclusively beneficial as Smad3 has diverse transcriptional regulatory effects in different cell types in the kidney.

Deletion of Smad3 protects the kidney from developing transforming growth factor (TGF)‐β1‐induced tubulointerstitial fibrosis, mesangial matrix expansion, and tubular basement membrane thickening, but not glomerular basement membrane thickening. The favorable effects of Smad3 deficiency can be explained by reduced deposition of collagen subtypes. The cell‐specific changes of matrix metalloproteinase expression can be a result of altered TGF‐β1 signaling.

The significance of matrix metalloproteinases in parasitic infections involving the central nervous system

Matrix metalloproteinases (MMPs) represent a large family of over twenty different secreted or membrane-bound endopeptidases, involved in many physiological (embryogenesis, precursor or stem cell mobilization, tissue remodeling during wound healing, etc.), as well as pathological (inflammation, tumor progression and metastasis in cancer, vascular pathology, etc.) conditions. For a long time, MMPs were considered only for the ability to degrade extracellular matrix (ECM) molecules (e.g., collagen, laminin, fibronectin) and to release hidden epitopes from the ECM. In the last few years, it has been fully elucidated that these molecules have many other functions, mainly related to the immune response, in consideration of their effects on cytokines, hormones and chemokines. Among others, MMP-2 and MMP-9 are endopeptidases of the MMP family produced by neutrophils, macrophages and monocytes. When infection is associated with leukocyte influx into specific organs, immunopathology and collateral tissue damage may occur. In this review, the involvement of MMPs and, in particular, of gelatinases in both protozoan and helminth infections will be described. In cerebral malaria, for example, MMPs play a role in the pathogenesis of such diseases. Also, trypanosomosis and toxoplasmosis will be considered for protozoan infections, as well as neurocysticercosis and angiostrongyloidosis, as regards helminthiases. All these situations have in common the proteolytic action on the blood brain barrier, mediated by MMPs.

Diabetic nephropathy and extracellular matrix

Diabetic nephropathy (DN) is a serious complication in diabetes. Major typical morphological changes are the result of changes in the extracellular matrix (ECM). Thus, basement membranes are thickened and the glomerular mesangial matrix and the tubulointerstitial space are expanded, due to increased amounts of ECM. One important ECM component, the proteoglycans (PGs), shows a more complex pattern of changes in DN. PGs in basement membranes are decreased but increased in the mesangium and the tubulointerstitial space. The amounts and structures of heparan sulfate chains are changed, and such changes affect levels of growth factors regulating cell proliferation and ECM synthesis, with cell attachment affecting endothelial cells and podocytes. Enzymes modulating heparan sulfate structures, such as heparanase and sulfatases, are implicated in DN. Other enzyme classes also modulate ECM proteins and PGs, such as matrix metalloproteinases (MMPs) and serine proteases, such as plasminogen activator, as well as their corresponding inhibitors. The levels of these enzymes and inhibitors are changed in plasma and in the kidneys in DN. Several growth factors, signaling pathways, and hyperglycemia per se affect ECM synthesis and turnover in DN. Whether ECM components can be used as markers for early kidney changes is an important research topic, whereas at present, the clinical use remains to be established.

Protease profiling of different biofluids in type 1 diabetes mellitus

OBJECTIVES

We aimed to disclose the proteolytic events underlying type 1 diabetes and related complication through protease profiling in the bodily fluids serum, urine and saliva.

DESIGN AND METHODS

Zymography followed by LC-MS/MS was performed for protease identification and quantitative comparison of proteolytic activity between healthy, type 1 diabetic patients with no complications and with retinopathy and nephropathy. Western blotting was also accomplished for MMP-9 and MMP-2 identification and expression analysis.

RESULTS

Only MMP-2 and MMP-9 were observed in serum with significantly increased levels and activity observed in diabetic patients. In urine and saliva other proteases besides MMPs were identified by MS and presented disease-dependent activity variations. Among these are complex MMP-9/Neutrophil gelatinase-associated lipocalin, aminopeptidase N, azurocidin and kallikrein 1 with more activity noticed in type 1 diabetes patients with nephropathy and/or retinopathy.

CONCLUSION

Our data highlight the usefulness of urine and saliva for the monitoring of type-1 diabetes-related proteolytic events, where aminopeptidase N, azurocidin and kallikrein 1 appear as promising screening targets for type 1 diabetes-related complications.

Matrix metalloproteinases in kidney homeostasis and diseases

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that have been increasingly linked to both normal physiology and abnormal pathology in the kidney. Collectively able to degrade all components of the extracellular matrix, MMPs were originally thought to antagonize the development of fibrotic diseases solely through digestion of excessive matrix. However, increasing evidence has shown that MMPs play a wide variety of roles in regulating inflammation, epithelial-mesenchymal transition, cell proliferation, angiogenesis, and apoptosis. We now have robust evidence for MMP dysregulation in a multitude of renal diseases including acute kidney injury, diabetic nephropathy, glomerulonephritis, inherited kidney disease, and chronic allograft nephropathy. The goal of this review is to summarize current findings regarding the role of MMPs in kidney diseases as well as the mechanisms of action of this family of proteases.

Proteases in Plasma and Kidney of db/db Mice as Markers of Diabetes-Induced Nephropathy

Db/db mice are overweight, dyslipidemic and develop diabetic complications, relevant for similar complications in human type 2 diabetes. We have used db/db and db/+ control mice to investigate alterations in proteinase expression and activity in circulation and kidneys by SDS-PAGE zymography, electron microscopy, immunohistochemistry, Western blotting, and in situ zymography. Plasma from db/db mice contained larger amounts of serine proteinases compared to db/+ mice. Kidneys from the db/db mice had a significantly larger glomerular surface area and somewhat thicker glomerular basement membranes compared to the db/+ mice. Furthermore, kidney extracts from db/+ mice contained metalloproteinases with M_r of approximately 92000, compatible with MMP-9, not observed in db/db mice. These results indicate that higher levels of serine proteinases in plasma may serve as potential markers for kidney changes in db/db mice, whereas a decrease in MMP-9 in the kidney may be related to the glomerular changes.

Upregulation of collagenase-1 and -3 in indomethacin-induced gastric ulcer in diabetic rats: role of melatonin

Collagenases are key proteases involved in inflammation and injury. We addressed whether collagenases have an association with the susceptibility of gastric injury under diabetes as well as the effect of melatonin on collagenases in ulcerated gastric tissues. Diabetes was induced in rats by a single dose of streptozotocin (STZ) followed by gastric ulceration using indomethacin, and melatonin's action was studied by its application prior to indomethacin exposure. Ulcer indices and damage were elevated significantly in gastric tissues of diabetic compared with nondiabetic rats. Melatonin reversed the effect of indomethacin during protection of gastric ulcers in diabetic rats. Matrix metalloproteinase (MMP)-13 (i.e., collagenase-3) was upregulated in diabetic gastric mucosa and enhanced further upon ulceration while melatonin ameliorated their activity. In addition, gastric tissues showed enhanced expression of both MMP-1 (i.e., collagenases-1) and -13 significantly in diabetic rats compared with nondiabetic animals and more so during ulceration while tissue inhibitors of metalloproteinase-1 (TIMP-1) showed an opposite trend. MMP-2 activities exhibited a ∼50% downregulation during gastric ulceration which were rescued by melatonin. Moreover, increased expression of both MMP-1 and -13 was mediated by activator protein-1 activation via extracellular signal-regulated kinase 1/2 which were parallel to upregulation of tumor necrosis factor-α, interleukin-1β, and heat shock protein-70 during ulceration. Melatonin arrested collagenase expression by downregulation of these signaling molecules thereby halting the progression of the disease. We conclude that diabetic gastric tissues are susceptible to ulceration and associated with MMP-1 and -13 upregulation in indomethacin-induced injury. Additionally, melatonin protects the gastric damage under diabetes via regulation of both MMP-1 and -13.

Serum 14-3-3; matrix metalloproteinases and their inhibitors' levels before and after cardiovascular surgery in diabetic and non-diabetic patients

AIMS

We sought to assess the serum levels of the main extracellular matrix components before and after surgery in order to differentiate the response of diabetic patients to acute wounds from that of non-diabetic patients.

METHODS

The serum levels of 14-3-3, Pro-MMP-1, MMP-3, and TIMP-1 were measured in diabetics (18 patients) and non-diabetics (22 patients) in samples obtained before a coronary artery bypass grafting operation and on the 1st, 3rd, and 5th postoperative days.

RESULTS

The diabetics had higher serum levels of 14-3-3 both in the pre- and postoperative phases. Nevertheless, there was a postoperative drop in these amounts in all the patients. There was no difference in the serum levels of Pro-MMP-1 between the two groups. In addition, the serum levels of MMP-3 on the 3rd and 5th postoperative days and also TIMP-1 (inhibitor of both MMPs) on all postoperative days were higher in the diabetics.

CONCLUSIONS

There was perfect synchronicity between the changes in the serum levels of these proteins and their functional nature in the injured tissue. Furthermore, the diabetic patients exhibited more changes in the levels of some of their extracellular enzymes in the wake of acute wounds; these changes were also traceable in the serum.

Matrix metalloproteinase activity assays: Importance of zymography

INTRODUCTION

Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases capable of degrading extracellular matrix, including the basement membrane. MMPs are associated with various physiological processes such as morphogenesis, angiogenesis, and tissue repair. Moreover, due to the novel non-matrix related intra- and extracellular targets of MMPs, dysregulation of MMP activity has been implicated in a number of acute and chronic pathological processes, such as arthritis, acute myocardial infarction, chronic heart failure, chronic obstructive pulmonary disease, inflammation, and cancer metastasis. MMPs are considered as viable drug targets in the therapy of the above diseases.

METHODS

For the development of selective MMP inhibitor molecules, reliable methods are necessary for target validation and lead development. Here, we discuss the major methods used for MMP assays, focusing on substrate zymography. We highlight some problems frequently encountered during sample preparations, electrophoresis, and data analysis of zymograms.

RESULTS AND DISCUSSION

Zymography is a widely used technique to study extracellular matrix-degrading enzymes, such as MMPs, from tissue extracts, cell cultures, serum or urine. This simple and sensitive technique identifies MMPs by the degradation of their substrate and by their molecular weight and therefore helps to understand the widespread role of MMPs in different pathologies and cellular pathways.