Matrix metalloproteinases in neuromuscular disease

The Potentials of Melatonin in the Prevention and Treatment of Bacterial Meningitis Disease

Bacterial meningitis (BM) is an acute infectious central nervous system (CNS) disease worldwide, occurring with 50% of the survivors left with a long-term serious sequela. Acute bacterial meningitis is more prevalent in resource-poor than resource-rich areas. The pathogenesis of BM involves complex mechanisms that are related to bacterial survival and multiplication in the bloodstream, increased permeability of blood-brain barrier (BBB), oxidative stress, and excessive inflammatory response in CNS. Considering drug-resistant bacteria increases the difficulty of meningitis treatment and the vaccine also has been limited to several serotypes, and the morbidity rate of BM still is very high. With recent development in neurology, there is promising progress for drug supplements of effectively preventing and treating BM. Several in vivo and in vitro studies have elaborated on understanding the significant mechanism of melatonin on BM. Melatonin is mainly secreted in the pineal gland and can cross the BBB. Melatonin and its metabolite have been reported as effective antioxidants and anti-inflammation, which are potentially useful as prevention and treatment therapy of BM. In bacterial meningitis, melatonin can play multiple protection effects in BM through various mechanisms, including immune response, antibacterial ability, the protection of BBB integrity, free radical scavenging, anti-inflammation, signaling pathways, and gut microbiome. This manuscript summarizes the major neuroprotective mechanisms of melatonin and explores the potential prevention and treatment approaches aimed at reducing morbidity and alleviating nerve injury of BM.

Matrix metalloproteinases in exercise and obesity

Matrix metalloproteinases (MMPs) are zinc- and calcium-dependent endoproteinases that have the ability to break down extracellular matrix. The large range of MMPs’ functions widens their spectrum of potential role as activators or inhibitors in tissue remodeling, cardiovascular diseases, and obesity. In particular, MMP-1, -2, and -9 may be associated with exercise and obesity. Thus, the current study reviewed the effects of different types of exercise (resistance and aerobic) on MMP-1, -2, and -9. Previous studies report that the response of MMP-2 and -9 to resistance exercise is dependent upon the length of exercise training, since long-term resistance exercise training increased both MMP-2 and -9, whereas acute bout of resistance exercise decreased these MMPs. Aerobic exercise produces an inconsistent result on MMPs, although some studies showed a decrease in MMP-1. Obesity is related to a relatively lower level of MMP-9, indicating that an exercise-induced increase in MMP-9 may positively influence obesity. A comprehensive understanding of the relationship between exercise, obesity, and MMPs does not exist yet. Future studies examining the acute and chronic responses of these MMPs using different subject models may provide a better understanding of the molecular mechanisms that are associated with exercise, obesity, and cardiovascular disease.

The expression and function of gelatinolytic activity at the rat neuromuscular junction upon physical exercise

The gelatinases MMP-9 and MMP-2 have been implicated in skeletal muscle adaptation to training; however, their specific role(s) in the different muscle types are only beginning to be unraveled. Recently, we found that treadmill running increased the activity and/or expression of these enzymes in myonuclei and in activated satellite cells of the soleus (Sol), but not extensor digitorum longus (EDL) muscles on the fifth day of training of adult rats. Here, we asked whether the gelatinases can be involved in physical exercise-induced adaptation of the neuromuscular compartment. To determine the subcellular localization of the gelatinolytic activity, we used high-resolution in situ zymography and immunofluorescence techniques. In both control and trained muscles, strong gelatinolytic activity was associated with myelin sheaths within intramuscular nerve twigs. In EDL, but not Sol, there was an increase in the gelatinolytic activity at the postsynaptic domain of the neuromuscular junction (NMJ). The increased activity was found within punctate structures situated in the vicinity of synaptic cleft of the NMJ, colocalizing with a marker of endoplasmic reticulum. Our results support the hypothesis that the gelatinolytic activity at the NMJ may be involved in NMJ plasticity.

Genetic variations within metalloproteinases impact on the prophylaxis of depressive phases in bipolar patients

BACKGROUND

The genetic background of the antidepressant response to pharmacological treatment in bipolar disorder (BD) remains elusive. This issue is of primary relevance in that the depressive phases of BD are difficult to treat and they are associated with suicide.

AIM

We investigated the role of a set of genetic variations (single-nucleotide polymorphisms) harbored by matrix metalloproteinases (MMPs) as predictors of response to treatment in depressed BD patients.

METHODS

654 BD patients from the publicly available Systematic Treatment Enhancement Program for Bipolar Disorder study were investigated. The outcome was the number of depressive events corrected by the number of times patients were assessed. Clinical and sociodemographic variables were tested as possible stratification factors and included in the analysis if necessary. Genetic predictors were 43 SNPs harbored by 17 MMPs. Imputation, quality check and pruning were conducted according to standards. RESULTS were corrected for multitesting.

RESULTS

rs486055 (MMP-10) was associated with the outcome. TT homozygotes had 5.08 ± 3.51 events, CT had 3.47 ± 3.18 and CC had 2.57 ± 2.96 depressive events corrected for the times they had been assessed. The time during which BD patients were observed was not significantly different between the rs486055 genotypes. We found evidence that MMP-10 may be a mediator of the number of depressive phases during BD. Due to the limits of the study including the small-to-medium sample size, the naturalistic design and the possible occurrence of false-positive findings, independent analyses are warranted.

Hydrogen sulfide and sodium nitroprusside compete to activate/deactivate MMPs in bone tissue homogenates

BACKGROUND

Bone microvascular remodeling is the primary predictor of bone structure and function. Remodeling by its very nature implies synthesis and degradation of the extracellular matrix. Normally, 50% of total protein in the vessel wall is elastin. During remodeling, elastin is degraded by specialized matrix metalloproteinases (MMPs). Because the turnover of elastin is 1000-fold slower than that of collagen, most of the elastin is replaced by stiffer collagen. Stiffer vessels impose pressure on the aortic valve, causing regurgitation and increased pulse pressure. On the other hand, high MMP activity will cause vascular dilatation, leading to aneurysm. Therefore, balanced constitutive remodeling is necessary for adequate bone structure and function. Interestingly, collagen-degrading MMPs are involved in various pathological conditions, including osteoporosis, osteoarthritis, and cardiovascular disease. Sodium nitroprusside is a nitric oxide donor that could potentially alter MMP activity via vasodilation in vivo, but can also produce peroxynitrite, which activates MMPs by combining with superoxide. Moreover, hydrogen sulfide is a known antioxidant as well as a vasodilator, and is also speculated to contribute directly to MMP activity. We hypothesized that hydrogen sulfide reduced activity of MMP in ex vivo bone tissue homogenates and that sodium nitroprusside would increase MMP activity in vitro.

METHODS

We surgically removed the tibia and femur from anesthetized mice, and prepared bone tissue homogenates using a mortar and pestle, measured the protein concentration with a spectrophotometer, and detected MMP activity using gelatin gel zymography.

RESULTS

Our data showed increased MMP activity at a sodium nitroprusside concentration of 1 μM, and MMP activity increased exponentially. There was a decrease in MMP activity with increasing hydrogen sulfide, beginning at 16 μM (P < 0.01) and continuing to 40 μM. Moreover, sodium nitroprusside 3 μM was able to overcome the decrease in MMP activity that occurred with hydrogen sulfide 40 μM; this resulted in a more pronounced exponential increase in MMP activity.

CONCLUSION

There are several substances that can potentially be used to decrease MMP activity and to alleviate pathological remodeling by MMPs.

Decrease of MMP-9 activity improves soleus muscle regeneration

The regeneration of skeletal muscles relies on the function of satellite cells that are quiescent myogenic precursors associated with adult skeletal muscle fibers. Upon injury, the satellite cells are activated, divide extensively, and differentiate into new myofibers. These events are accompanied by the remodeling of the surrounding extracellular matrix, which is mediated by variety of factors, including matrix metalloproteinases (MMPs). Regeneration of certain type of muscles, such as Soleus slow twitch muscle, is often inefficient and hindered by the development of fibrosis. Here, we studied the effect of inhibition of MMP-9 and MMP-2 activity on the Soleus muscle regeneration in vivo and on the in vitro differentiation of myoblasts derived from this muscle. Using in situ and in-gel zymography, we tested the activity of these two MMPs in vivo, during regeneration of the muscle, and in vitro, during differentiation of the myoblasts. We also analyzed the histology of regenerating muscles and morphology of differentiating myoblasts. All these analyses showed that treatment with doxycycline and anti-MMP-9, but not MMP-2 antibody, significantly improved Soleus muscle regeneration and ameliorated development of excessive fibrosis, as well as delayed myoblast proliferation and differentiation in vitro.

Fine-structural distribution of MMP-2 and MMP-9 activities in the rat skeletal muscle upon training: a study by high-resolution in situ zymography

Matrix metalloproteinases (MMPs) are key regulators of extracellular matrix remodeling, but have also important intracellular targets. The purpose of this study was to examine the activity and subcellular localization of the gelatinases MMP-2 and MMP-9 in skeletal muscle of control and physically trained rats. In control hind limb muscle, the activity of the gelatinases was barely detectable. In contrast, after 5 days of intense exercise, in Soleus (Sol), but not Extensor digitorum longus (EDL) muscle, significant upregulation of gelatinolytic activity in myofibers was observed mainly in the nuclei, as assessed by high resolution in situ zymography. The nuclei of quiescent satellite cells did not contain the activity. Within the myonuclei, the gelatinolytic activity colocalized with an activated RNA Polymerase II. Also in Sol, but not in EDL, there were few foci of mononuclear cells with strongly positive cytoplasm, associated with apparent necrotic myofibers. These cells were identified as activated satellite cells/myoblasts. No extracellular gelatinase activity was observed. Gel zymography combined with subcellular fractionation revealed training-related upregulation of active MMP-2 in the nuclear fraction, and increase of active MMP-9 in the cytoplasmic fraction of Sol. Using RT-PCR, selective increase in MMP-9 mRNA was observed. We conclude that training activates nuclear MMP-2, and increases expression and activity of cytoplasmic MMP-9 in Sol, but not in EDL. Our results suggest that the gelatinases are involved in muscle adaptation to training, and that MMP-2 may play a novel role in myonuclear functions.

A Novel Mathematical Approach to Define the Genes/SNPs Conferring Risk or Protection in Sporadic Amyotrophic Lateral Sclerosis Based on Auto Contractive Map Neural Networks and Graph Theory

Background. Complex diseases like amyotrophic lateral sclerosis (ALS) implicate phenotypic and genetic heterogeneity. Therefore, multiple genetic traits may show differential association with the disease. The Auto Contractive Map (AutoCM), belonging to the Artificial Neural Network (ANN) architecture, "spatializes" the correlation among variables by constructing a suitable embedding space where a visually transparent and cognitively natural notion such as "closeness" among variables reflects accurately their associations. Results. In this pilot case-control study single nucleotide polymorphism (SNP) in several genes has been evaluated with a novel data mining approach based on an AutoCM. We have divided the ALS dataset into two dataset: Cases and Control dataset; we have applied to each one, independently, the AutoCM algorithm. Six genetic variants were identified which differently contributed to the complexity of the system: three of the above genes/SNPs represent protective factors, APOA4, NOS3, and LPL, since their contribution to the whole complexity resulted to be as high as 0.17. On the other hand ADRB3, LIPC, and MMP3, whose hub relevancies contribution resulted to be as high as 0.13, seem to represent susceptibility factors. Conclusion. The biological information available on these six polymorphisms is consistent with possible pathogenetic pathways related to ALS.

EMMPRIN levels in serum of patients with amyotrophic lateral sclerosis

OBJECTIVES

There are evidence that extracellular matrix metalloproteinases (MMPs) may be implicated in the pathophysiology of amyotrophic lateral sclerosis (ALS). The extracellular matrix metalloproteinase inducer (EMMPRIN) is said to increase the production of MMPs in cells. The aim of the study was to investigate serum EMMPRIN levels in patients with ALS.

MATERIALS AND METHODS

The study included 50 patients with ALS and 50 patients from the control group. Serum EMMPRIN levels were measured using the enzyme-linked immunosorbent method.

RESULTS

The study showed that EMMPRIN levels are significantly increased in the serum of the whole group of patients with ALS when compared to the control group and are significantly increased in patients with ALS with severe clinical state compared to patients with mild clinical state (P < 0.05). There was a significant correlation of serum EMMPRIN levels with severity of clinical state of patients with ALS (P < 0.05).

CONCLUSION

The results indicate that EMMPRIN is implicated in pathophysiology of ALS and may be the marker of clinical state severity.

Homocysteine mediated decrease in bone blood flow and remodeling: role of folic acid

Deficiencies in folate lead to increased serum concentrations of homocysteine (Hcy), which is known as hyperhomocysteinemia (HHcy), is associated with bone disorders. Although, Hcy accumulates collagen in bone and contribute to decrease in bone strength. The mechanism of Hcy induced bone loss and remodeling is unclear. Therefore, the present study was aimed to determine the role of folic acid (FA) in genetically HHcy-associated decrease in bone blood flow and remodeling. Wild type (WT) and cystathionine-β-synthase heterozygous (CBS+/-) mice were used in this study and supplemented with or without FA (300 mg/kg, Hcy reducing agent) in drinking water for 6 weeks. The tibial bone blood flow was measured by laser Doppler and ultrasonic flow probe method. The tibial bone density (BD) was assessed by dual energy X-ray absorptiometry. The bone homogenates were analyzed for oxidative stress, NOX-4 as oxidative marker and thioredoxin-1 (Trx-1) as anti-oxidant marker, bone remodeling (MMP-9) and bio-availability of nitric oxide (eNOS/iNOS/NO) by Western blot method. The results suggested that there was decrease in tibial blood flow in CBS+/- mice. The BD was also reduced in CBS+/- mice. There was an increase in NOX-4, iNOS, MMP-9 protein as well as MMP-9 activity in CBS+/- mice and decrease in Trx-1, eNOS protein levels, in part by decreasing NO bio-availability in CBS+/- mice. Interestingly, these effects were ameliorated by FA and suggested that FA supplementation may have therapeutic potential against genetically HHcy induced bone loss.

Cerebral microvascular endothelium and the pathogenesis of neurodegenerative diseases

Diseases of the central nervous system (CNS) pose a significant health challenge, but despite their diversity, they share many common features and mechanisms. For example, endothelial dysfunction has been implicated as a crucial event in the development of several CNS disorders, such as Alzheimer disease, Parkinson disease, amyotrophic lateral sclerosis, multiple sclerosis, human immunodeficiency virus (HIV)-1-associated neurocognitive disorder and traumatic brain injury. Breakdown of the blood–brain barrier (BBB) as a result of disruption of tight junctions and transporters, leads to increased leukocyte transmigration and is an early event in the pathology of these disorders. The brain endothelium is highly reactive because it serves as both a source of, and a target for, inflammatory proteins and reactive oxygen species. BBB breakdown thus leads to neuroinflammation and oxidative stress, which are implicated in the pathogenesis of CNS disease. Furthermore, the physiology and pathophysiology of endothelial cells are closely linked to the functioning of their mitochondria, and mitochondrial dysfunction is another important mediator of disease pathology in the brain. The high concentration of mitochondria in cerebrovascular endothelial cells might account for the sensitivity of the BBB to oxidant stressors. Here, we discuss how greater understanding of the role of BBB function could lead to new therapeutic approaches for diseases of the CNS that target the dynamic properties of brain endothelial cells.

Disruption of neurovascular unit prior to motor neuron degeneration in amyotrophic lateral sclerosis

Recent reports suggest that functional or structural defect of vascular components are implicated in amyotrophic lateral sclerosis (ALS) pathology. In the present study, we examined a possible change of the neurovascular unit consisting of endothelium (PCAM-1), tight junction (occludin), and basement membrane (collagen IV) in relation to a possible activation of MMP-9 in ALS patients and ALS model mice. We found that the damage in the neurovascular unit was more prominent in the outer side and preferentially in the anterior horn of ALS model mice. This damage occurred prior to motor neuron degeneration and was accompanied by MMP-9 up-regulation. We also found the dissociation between the PCAM-1-positive endothelium and GFAP-positive astrocyte foot processes in both humans and the animal model of ALS. The present results indicate that perivascular damage precedes the sequential changes of the disease, which are held in common between humans and the animal model of ALS, suggesting that the neurovascular unit is a potential target for therapeutic intervention in ALS.

Matrix metalloproteinases and their tissue inhibitors in serum and cerebrospinal fluid of patients with amyotrophic lateral sclerosis

BACKGROUND AND PURPOSE

Matrix metalloproteinases (MMPs) are implicated in the pathogenesis of motor neuron degeneration in amyotrophic lateral sclerosis (ALS). We investigated the expression of MMPs and tissue inhibitors of matrix metalloproteinases (TIMPs) in serum and cerebrospinal fluid (CSF) correlating the results with age, disease duration and the clinical course.

METHODS

The material consisted of 30 ALS patients and 15 age-matched healthy controls. ELISA method to determine the expression of MT-MMP-1, MMP-2, MMP-9, TIMP-1 and TIMP-2 in serum and CSF was used. MMP-2 and MMP-9 by zymography was also tested.

RESULTS

In serum MT-MMP-1, MMP-2, MMP-9 and TIMP-1 expression was increased, especially in mild ALS cases. TIMP-2 values were normal. In CSF MT-MMP-1, MMP-2 and TIMP-1 level was either increased or normal, that of MMP-9 was decreased. TIMP-2 did not change. No correlation of MMPs and TIMP-1 expression in serum and CSF and the age of the patients was found. A correlation was observed between MMPs and TIMPs and disease duration.

CONCLUSIONS

Increased level of MMPs and TIMP-1 of ALS patients may reflect the degeneration process of motor neurons and skeletal muscles and/or is associated with tissues remodeling. The low level of MMP-9 in CSF may result from impaired balance between MMP-9 and TIMP-1 and/or its increased intrathecal degradation and physical clearance. Although the role of changed MMPs/TIMPs level in the pathogenesis of ALS is not clear their analysis in serum may be used as prognostic factor and a potential marker for monitoring treatment effects.

Matrix metalloproteinase-2 is involved in myelination of dorsal root ganglia neurons

Matrix metalloproteinases (MMPs) comprise a large family of endopeptidases that are capable of degrading all extracellular matrix components. There is increasing evidence that MMPs are not only involved in tissue destruction but may also exert beneficial effects during axonal regeneration and nerve remyelination. Here, we provide evidence that MMP-2 (gelatinase A) is associated with the physiological process of myelination in the peripheral nervous system (PNS). In a myelinating co-culture model of Schwann cells and dorsal root ganglia neurons, MMP-2 expression correlated with the degree of myelination as determined by immunocytochemistry, zymography, and immunosorbent assay. Modulation of MMP-2 activity by chemical inhibitors led to incomplete and aberrant myelin formation. In vivo MMP-2 expression was detected in the cerebrospinal fluid (CSF) of patients with Guillain-Barré syndrome as well as in CSF and sural nerve biopsies of patients with chronic inflammatory demyelinating polyneuropathy. Our findings suggest an important, previously unrecognized role for MMP-2 during myelination in the PNS. Endogenous or exogenous modulation of MMP-2 activity may be a relevant target to enhance regeneration in demyelinating diseases of the PNS.