ADAM-10 and ADAM-17 in the inflamed human CNS

Potential Mechanisms Underlying COVID-19-Mediated Central and Peripheral Demyelination: Roles of the RAAS and ADAM-17

Demyelination is among the most conspicuous neurological sequelae of SARS-CoV-2 infection (COVID-19) in both the central (CNS) and peripheral (PNS) nervous systems. Several hypotheses have been proposed to explain the mechanisms underlying demyelination in COVID-19. However, none have considered the SARS-CoV-2's effects on the renin-angiotensin-aldosterone system (RAAS). Therefore, our objective in this review is to evaluate how RAAS imbalance, caused by direct and indirect effects of SARS-CoV-2 infection, could contribute to myelin loss in the PNS and CNS. In the PNS, we propose that demyelination transpires from two significant changes induced by SARS-CoV-2 infection, which include upregulation of ADAM-17 and induction of lymphopenia. Whereas, in the CNS, demyelination could result from RAAS imbalance triggering two alterations: (1) a decrease in angiotensin type II receptor (AT2R) activity, responsible for restraining defense cells' action on myelin; (2) upregulation of ADAM-17 activity, leading to impaired maturation of oligodendrocytes and myelin formation. Thus, we hypothesize that increased ADAM-17 activity and decreased AT2R activity play roles in SARS-CoV-2 infection-mediated demyelination in the CNS.

The role of biogenic amines in the modulation of monocytes in autoimmune neuroinflammation

Multiple sclerosis (MS) is inflammatory demyelinating and neurodegenerative disease of the central nervous system (CNS) with autoimmune mechanism of development. The study of the neuroimmune interactions is one of the most developing directions in the research of the pathogenesis of MS. The influence of biogenic amines on the pathogenesis of experimental autoimmune encephalomyelitis (EAE) and MS was shown by the modulation of subsets of T-helper cells and B-cells, which plays a crucial role in the autoimmunity of the CNS. However, along with T- and B-cells the critical involvement of mononuclear phagocytes such as dendritic cells, macrophages, and monocytes in the development of neuroinflammation also was shown. It was demonstrated that the activation of microglial cells (resident macrophages of the CNS) could initiate the neuroinflammation in the EAE, suggesting their role at an early stage of the disease. In contrast, monocytes, which migrate from the periphery into the CNS through the blood-brain barrier, mediate the effector phase of the disease and cause neurological disability in EAE. In addition, the clinical efficacy of the therapy with depletion of the monocytes in EAE was shown, suggesting their crucial role in the autoimmunity of the CNS. Biogenic amines, such as epinephrine, norepinephrine, dopamine, and serotonin are direct mediators of the neuroimmune interaction and may affect the pathogenesis of EAE and MS by modulating the immune cell activity and cytokine production. The anti-inflammatory effect of targeting the biogenic amines receptors on the pathogenesis of EAE and MS by suppression of Th17- and Th1-cells, which are critical for the CNS autoimmunity, was shown. However, the latest data showed the potential ability of biogenic amines to affect the functions of the mononuclear phagocytes and their involvement in the modulation of neuroinflammation. This article reviews the literature data on the role of monocytes in the pathogenesis of EAE and MS. The data on the effect of targeting of biogenic amine receptors on the function of monocytes are presented.

Disruption of the ADAM17/NF-κB feedback loop in astrocytes ameliorates HIV-1 Tat-induced inflammatory response and neuronal death

A disintegrin and metalloproteinases (ADAMs) are involved in multiple neurodegenerative diseases. However, the roles and mechanisms of ADAMs in HIV-associated neurocognitive disorder (HAND) remain unclear. Transactivator of transcription (Tat) induces inflammatory response in astrocytes, thereby leading to neuronal apoptosis in the central nervous system. In this study, we determined that ADAM17 expression was upregulated during soluble Tat stimulus in HEB astroglial cells. Inhibition of ADAM17 suppressed Tat-induced pro-inflammatory cytokines production and rescued the astrocytes-derived conditioned media (ACM)-mediated SH-SY5Y neural cells apoptosis. Moreover, ADAM17 mediated Tat-triggered inflammatory response in a NF-κB-dependent manner. Conversely, Tat induced ADAM17 expression via NF-κB signaling pathway. In addition, pharmacological inhibition of NF-κB signaling inhibited Tat-induced inflammatory response, which could be rescued by overexpression of ADAM17. Taken together, our study clarifies the potential role of the ADAM17/NF-κB feedback loop in Tat-induced inflammatory response in astrocytes and the ACM-mediated neuronal death, which could be a novel therapeutic target for relief of HAND.

The Cytokine CX3CL1 and ADAMs/MMPs in Concerted Cross-Talk Influencing Neurodegenerative Diseases

Neuroinflammation plays a fundamental role in the development and progression of neurodegenerative diseases. It could therefore be said that neuroinflammation in neurodegenerative pathologies is not a consequence but a cause of them and could represent a therapeutic target of neuronal degeneration. CX3CL1 and several proteases (ADAMs/MMPs) are strongly involved in the inflammatory pathways of these neurodegenerative pathologies with multiple effects. On the one hand, ADAMs have neuroprotective and anti-apoptotic effects; on the other hand, they target cytokines and chemokines, thus causing inflammatory processes and, consequently, neurodegeneration. CX3CL1 itself is a cytokine substrate for the ADAM, ADAM17, which cleaves and releases it in a soluble isoform (sCX3CL1). CX3CL1, as an adhesion molecule, on the one hand, plays an inhibiting role in the pro-inflammatory response in the central nervous system (CNS) and shows neuroprotective effects by binding its membrane receptor (CX3CR1) present into microglia cells and maintaining them in a quiescent state; on the other hand, the sCX3CL1 isoform seems to promote neurodegeneration. In this review, the dual roles of CX3CL1 and ADAMs/MMPs in different neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (MH), and multiple sclerosis (MS), are investigated.

Plasma ADAM-10 levels and functional outcome of acute primary basal ganglia hemorrhage

BACKGROUND

The a-secretase A disintegrin and metalloprotease-10 (ADAM-10) may have deleterious effects in acute brain injury. This study was designed to discern if a relationship between plasma ADAM-10 levels and functional outcome exists in patients with intracerebral hemorrhage (ICH).

METHODS

A total of 109 patients with basal ganglia hemorrhage and 100 healthy controls were included. Their plasma ADAM-10 levels were gauged. Ninety-day prognosis was assessed and poor outcome was defined as death or major disability (modified Rankin Scale score of 3 or greater).

RESULTS

Plasma ADAM-10 levels were substantially elevated in patients, as compared to controls. ADAM-10 levels were independently correlated with hematoma size and National Institutes of Health Stroke Scale (NIHSS) score. Plasma ADAM-10, NIHSS score and hematoma size emerged as the independent predictors for 90-day poor outcome. Under receiver operating characteristic curve, plasma ADAM-10 levels exhibited similar prognostic capability, as compared to hematoma size and NIHSS score; moreover, it significantly improved prognostic abilities of NIHSS and hematoma size.

CONCLUSIONS

Rising plasma ADAM-10 levels are independently related to increasing severity and poor long-term functional outcome after hemorrhagic stroke, substantializing serum ADAM-10 as a useful prognostic biomarker of ICH.

Staphylococcus aureus-Derived α-Hemolysin Evokes Generation of Specialized Pro-resolving Mediators Promoting Inflammation Resolution

Underlying mechanisms of how infectious inflammation is resolved by the host are incompletely understood. One hallmark of inflammation resolution is the activation of specialized pro-resolving mediators (SPMs) that enhance bacterial clearance and promote tissue repair. Here, we reveal α-hemolysin (Hla) from Staphylococcus aureus as a potent elicitor of SPM biosynthesis in human M2-like macrophages and in the mouse peritoneum through selective activation of host 15-lipoxygenase-1 (15-LOX-1). S. aureus-induced SPM formation in M2 is abolished upon Hla depletion or 15-LOX-1 knockdown. Isolated Hla elicits SPM formation in M2 that is reverted by inhibition of the Hla receptor ADAM10. Lipid mediators derived from Hla-treated M2 accelerate planarian tissue regeneration. Hla but not zymosan provokes substantial SPM formation in the mouse peritoneum, devoid of leukocyte infiltration and pro-inflammatory cytokine secretion. Besides harming the host, Hla may also exert beneficial functions by stimulating SPM production to promote the resolution of infectious inflammation.

Jordan et al. reveal that α-hemolysin from Staphylococcus aureus stimulates specialized pro-resolving mediator (SPM) formation through activation of 15-lipoxygenase-1 in human macrophages involving ADAM10. The host may exploit α-hemolysin as an SPM inducer to better cope with S. aureus infections and to promote inflammation resolution and tissue regeneration.

Downregulation of miR-125a-5p and miR-218-5p in Peripheral Blood Mononuclear Cells of Patients with Relapsing-Remitting Multiple Sclerosis

Multiple sclerosis (MS) is a chronic neuroinflammatory disease of the brain and spinal cord. Evidences have demonstrated that microRNAs (miRNAs) are involved in the pathological process of MS that may confer a valuable diagnostic biomarker for disease diagnosis, prognosis, and treatment. Hence, we assessed the expression pattern of miR-125a-5p and miR-218-5p in the peripheral blood mononuclear cells (PBMCs) of subjects with relapsing-remitting multiple sclerosis (RRMS). We recruited 50 RRMS patients and 50 age- and sex-matched healthy control subjects. PBMCs were isolated from the peripheral blood samples, RNA content was extracted, cDNA was synthesized, and finally expression level of miRNAs was determined using quantitative real-time PCR. Our data indicate significant downregulation of both miR-125a-5p and miR-218-5p in RRMS patients compared to healthy controls (P< .0001). The levels of both miRNAs were significantly downregulated in an age-dependent manner compared with consistent healthy control groups (30-40 years old P< .0001). Expression level of miR-218-5p was significantly changed in only female patients (Female group P< .0001; Male group P= .12). Receiver operating characteristic (ROC) curve data indicated that the expression levels of both miRNAs were able to discriminate RRMS patients from healthy subjects (P< .05). Moreover, bioinformatic enrichment analysis revealed that the target genes of these miRNAs had cardinal roles in the regulation of key biological pathways involved in the clinical course and pathogenesis of MS. Collectively, our results suggested that miR-125a-5p and miR-218-5p play a role in RRMS pathogenesis and have an age- and sex-dependent expression pattern in these patients.

The p75NTR and its carboxyl-terminal fragment exert opposing effects on melanoma cell proliferation and apoptosis via modulation of the NF-κB pathway

The p75 neurotrophin receptor (p75NTR ), a member of the tumor necrosis factor superfamily of receptors, is sensitive to proteolysis and has been observed to be expressed in various cancers. However, the roles of p75NTR and its proteolytic fragments in tumorigenesis remain incompletely understood. Here, we report that the proportion of the p75NTR carboxyl-terminal fragment (p75NTR -CTF) is much higher than that of the full-length p75NTR (p75NTR -FL) in melanoma cells. Whereas p75NTR -FL positively regulates apoptosis, p75NTR -CTF promotes cell proliferation and survival, as well as increasing sorafenib resistance in vivo and in vitro. Moreover, p75NTR -CTF activates the nuclear factor kappa B pathway and enhances the mRNA and protein levels of its downstream genes c-IAP1/2, FLIP, bFGF, IL8 and VEGF. On the contrary, p75NTR -FL inhibits these processes. Taken together, these findings demonstrate that p75NTR -CTF and p75NTR -FL have opposing functions in melanoma cells, suggesting that the ratio of the two proteins affects the balance between cell death and survival. The presence of distinct p75NTR proteolytic fragments may affect biological outcomes in tumor cells.

Matrix metalloproteinase signals following neurotrauma are right on cue

Neurotrauma, a term referencing both traumatic brain and spinal cord injuries, is unique to neurodegeneration in that onset is clearly defined. From the perspective of matrix metalloproteinases (MMPs), there is opportunity to define their temporal participation in injury and recovery beginning at the level of the synapse. Here we examine the diverse roles of MMPs in the context of targeted insults (optic nerve lesion and hippocampal and olfactory bulb deafferentation), and clinically relevant focal models of traumatic brain and spinal cord injuries. Time-specific MMP postinjury signaling is critical to synaptic recovery after focal axonal injuries; members of the MMP family exhibit a signature temporal profile corresponding to axonal degeneration and regrowth, where they direct postinjury reorganization and synaptic stabilization. In both traumatic brain and spinal cord injuries, MMPs mediate early secondary pathogenesis including disruption of the blood-brain barrier, creating an environment that may be hostile to recovery. They are also critical players in wound healing including angiogenesis and the formation of an inhibitory glial scar. Experimental strategies to reduce their activity in the acute phase result in long-term neurological recovery after neurotrauma and have led to the first clinical trial in spinal cord injured pet dogs.

Targeting senescence to delay progression of multiple sclerosis

Multiple sclerosis (MS) is a chronic and often progressive, demyelinating disease of the central nervous system (CNS) white and gray matter and the single most common cause of disability in young adults. Age is one of the factors most strongly influencing the course of progression in MS. One of the hallmarks of aging is cellular senescence. The elimination of senescent cells with senolytics has very recently been shown to delay age-related dysfunction in animal models for other neurological diseases. In this review, the possible link between cellular senescence and the progression of MS is discussed, and the potential use of senolytics as a treatment for progressive MS is explored. Currently, there is no cure for MS and there are limited treatment options to slow the progression of MS. Current treatment is based on immunomodulatory approaches. Various cell types present in the CNS can become senescent and thus potentially contribute to MS disease progression. We propose that, after cellular senescence has indeed been shown to be directly implicated in disease progression, administration of senolytics should be tested as a potential therapeutic approach for the treatment of progressive MS.

Levels of ADAM10 are reduced in Alzheimer's disease CSF

Background

The disintegrin metalloproteinase 10 (ADAM10) is the main α-secretase acting in the non-amyloidogenic processing of the amyloid precursor protein. This study assesses whether ADAM10 is present in cerebrospinal fluid (CSF), and whether it has potential as a biomarker for Alzheimer’s disease (AD).

Methods

ADAM10 was characterized in human CSF samples by immunoprecipitation and western blotting using antibodies specific for different domains of the protein and by ultracentrifugation in sucrose density gradients. Samples from AD patients (n = 20) and age-matched non-AD controls (n = 20) were characterized for classical CSF biomarkers, Aβ42, T-tau, or P-tau by ELISA, and assayed for soluble ADAM10 levels by western blotting.

Results

We found that ADAM10 is present in human CSF as several distinct species: an immature form retaining the prodomain (proADAM10; ~ 80 kDa), a mature unprocessed full-length form (ADAM10f; ~ 55 kDa), and a truncated large soluble form released from the membrane (sADAM10; ~ 50 kDa). Fractionation by ultracentrifugation on sucrose density gradients showed that the ADAM10f and sADAM10 species form large complexes. Immunoblotting revealed a significant decrease in ADAM10f and sADAM10 in AD CSF compared to control CSF, while proADAM10 levels remained unaltered.

Conclusions

Several forms of ADAM10 are present in CSF, mainly assembled as high-molecular weight complexes. The determination of the levels of mature forms of CSF-ADAM10 may be useful as a biomarker for AD.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1255-9) contains supplementary material, which is available to authorized users.

Profiling of metalloprotease activities in cerebrospinal fluids of patients with neoplastic meningitis

Background

Neoplastic invasion into leptomeninges and subarachnoid space, resulting in neoplastic meningitis (NM) is a fatal complication of advanced solid and hematological neoplasms. Identification of malignant involvement of the cerebrospinal fluid (CSF) early in the disease course has crucial prognostic and therapeutic implications, but remains challenging. As indicators of extracellular matrix (ECM) degradation and breakdown of the blood–brain-barrier, Matrix Metalloproteases (MMPs) and A Disintegrin and Metalloproteases (ADAMs) are potential analytes for cerebral pathophysiology and metastatic dissemination of tumor cells into the CSF.

Methods

We compared protease activities in CSF samples from patients with NM and control individuals using FRET-based metalloprotease substrates with distinct enzyme selectivity profiles in a real-time, multiplex approach termed “proteolytic activity matrix assay” (PrAMA). Protease activity dynamics can be tracked by fluorescence changes over time. By simultaneously monitoring a panel of 5 FRET-substrate cleavages, a proteolytic signature can be identified and analyzed to infer the activities of multiple specific proteases. Distinct patterns of substrate cleavage comparing disease vs. control samples allow rapid, reproducible and sensitive discrimination even in small volumes of CSF.

Results

Individual substrate cleavage rates were linked to distinct proteases, and PrAMA computational inference implied increased activities of MMP-9, ADAM8 and ADAM17 (4–5-fold on average) in CSF samples from NM patients that were inhibitable by the metalloprotease inhibitor batimastat (BB-94). The activities of these proteases correlated with blood–brain barrier impairment. Notably, CSF cell counts were not found to directly reflect the protease activities observed in CSF samples from NM patients; this may explain the frequent clinical observation of negative cytology in NM patients.

Conclusion

PrAMA analysis of CSF samples is a potential diagnostic method for sensitive detection of NM and may be suitable for the clinical routine.

Electronic supplementary material

The online version of this article (doi:10.1186/s12987-017-0070-5) contains supplementary material, which is available to authorized users.

Fine Tuning Cell Migration by a Disintegrin and Metalloproteinases

Cell migration is an instrumental process involved in organ development, tissue homeostasis, and various physiological processes and also in numerous pathologies. Both basic cell migration and migration towards chemotactic stimulus consist of changes in cell polarity and cytoskeletal rearrangement, cell detachment from, invasion through, and reattachment to their neighboring cells, and numerous interactions with the extracellular matrix. The different steps of immune cell, tissue cell, or cancer cell migration are tightly coordinated in time and place by growth factors, cytokines/chemokines, adhesion molecules, and receptors for these ligands. This review describes how a disintegrin and metalloproteinases interfere with several steps of cell migration, either by proteolytic cleavage of such molecules or by functions independent of proteolytic activity.

Heightened cleavage of Axl receptor tyrosine kinase by ADAM metalloproteases may contribute to disease pathogenesis in SLE

Systemic lupus erythematosus (SLE) is characterized by antibody-mediated chronic inflammation in the kidney, lung, skin, and other organs to cause inflammation and damage. Several inflammatory pathways are dysregulated in SLE, and understanding these pathways may improve diagnosis and treatment. In one such pathway, Axl tyrosine kinase receptor responds to Gas6 ligand to block inflammation in leukocytes. A soluble form of the Axl receptor ectodomain (sAxl) is elevated in serum from patients with SLE and lupus-prone mice. We hypothesized that sAxl in SLE serum originates from the surface of leukocytes and that the loss of leukocyte Axl contributes to the disease. We determined that macrophages and B cells are a source of sAxl in SLE and in lupus-prone mice. Shedding of the Axl ectodomain from the leukocytes of lupus-prone mice is mediated by the matrix metalloproteases ADAM10 and TACE (ADAM17). Loss of Axl from lupus-prone macrophages renders them unresponsive to Gas6-induced anti-inflammatory signaling in vitro. This phenotype is rescued by combined ADAM10/TACE inhibition. Mice with Axl-deficient macrophages develop worse disease than controls when challenged with anti-glomerular basement membrane (anti-GBM) sera in an induced model of nephritis. ADAM10 and TACE also mediate human SLE PBMC Axl cleavage. Collectively, these studies indicate that increased metalloprotease-mediated cleavage of leukocyte Axl may contribute to end organ disease in lupus. They further suggest dual ADAM10/TACE inhibition as a potential therapeutic modality in SLE.

N-cadherin promotes recruitment and migration of neural progenitor cells from the SVZ neural stem cell niche into demyelinated lesions

Discrete cellular microenvironments regulate stem cell pools and their development, as well as function in maintaining tissue homeostasis. Although the signaling elements modulating neural progenitor cells (NPCs) of the adult subventricular zone (SVZ) niche are fairly well understood, the pathways activated following injury and the resulting outcomes, are less clear. In the present study, we used mouse models of demyelination and proteomics analysis to identify molecular cues present in the adult SVZ niche during injury, and analyzed their role on NPCs in the context of promoting myelin repair. Proteomic analysis of SVZ tissue from mice with experimental demyelination identified several proteins that are known to play roles in NPC proliferation, adhesion, and migration. Among the proteins found to be upregulated were members of the N-cadherin signaling pathway. During the onset of demyelination in the subcortical white matter (SCWM), activation of epidermal growth factor receptor (EGFR) signaling in SVZ NPCs stimulates the interaction between N-cadherin and ADAM10. Upon cleavage and activation of N-cadherin signaling by ADAM10, NPCs undergo cytoskeletal rearrangement and polarization, leading to enhanced migration out of the SVZ into demyelinated lesions of the SCWM. Genetically disrupting either EGFR signaling or ADAM10 inhibits this pathway, preventing N-cadherin regulated NPC polarization and migration. Additionally, in vivo experiments using N-cadherin gain- and loss-of-function approaches demonstrated that N-cadherin enhances the recruitment of SVZ NPCs into demyelinated lesions. Our data revealed that EGFR-dependent N-cadherin signaling physically initiated by ADAM10 cleavage is the response of the SVZ niche to promote repair of the injured brain.

Involvement of soluble Fas Ligand in germ cell apoptosis in testis of rats undergoing autoimmune orchitis

Experimental autoimmune orchitis (EAO) is a model of chronic inflammation and infertility useful for studying immune and germ cell (GC) interactions. EAO is characterized by severe damage of seminiferous tubules (STs) with GCs that undergo apoptosis and sloughing. Based on previous results showing that Fas-Fas Ligand (L) system is one of the main mediators of apoptosis in EAO, in the present work we studied the involvement of Fas and the soluble form of FasL (sFasL) in GC death induction. EAO was induced in rats by immunization with testis homogenate and adjuvants; control (C) rats were injected with adjuvants; a group of non-immunized normal (N) rats was also studied. Activation of Fas employing an anti-Fas antibody decreased viability (trypan blue exclusion test) and induced apoptosis (TUNEL) of GCs from STs of N and EAO rats, an effect more pronounced on GCs from EAO STs. By Western blot we detected an increase in sFasL content in the testicular fluid of rats with severe EAO compared to N and C rats. By intratesticular injection of FasL conjugated to Strep-Tag molecule (FasL-Strep, BioTAGnology) and its immunofluorescent localization, we demonstrated that sFasL is able to enter the adluminal compartment of the STs. Moreover, FasL-Strep induced GC apoptosis in testicular fragments of N rats. By flow cytometry, we detected an increase in the number of membrane FasL-expressing CD4+ and CD8+ T cells in testis during EAO development but no expression of FasL by macrophages. Our results demonstrate that sFasL is locally produced in the chronically inflamed testis and that this molecule is able to enter the adluminal compartment of STs and induce apoptosis of Fas-bearing GCs.

MT5-MMP, ADAM-10, and N-cadherin act in concert to facilitate synapse reorganization after traumatic brain injury

Matrix metalloproteinases (MMPs) influence synaptic recovery following traumatic brain injury (TBI). Membrane type 5-matrix metalloproteinase (MT5-MMP) and a distintegrin and metalloproteinase-10 (ADAM-10) are membrane-bound MMPs that cleave N-cadherin, a protein critical to synapse stabilization. This study examined protein and mRNA expression of MT5-MMP, ADAM-10, and N-cadherin after TBI, contrasting adaptive and maladaptive synaptogenesis. The effect of MMP inhibition on MT5-MMP, ADAM-10, and N-cadherin was assessed during maladaptive plasticity and correlated with synaptic function. Rats were subjected to adaptive unilateral entorhinal cortical lesion (UEC) or maladaptive fluid percussion TBI+bilateral entorhinal cortical lesion (TBI+BEC). Hippocampal MT5-MMP and ADAM-10 protein was significantly elevated 2 and 7 days post-injury. At 15 days after UEC, each MMP returned to control level, while TBI+BEC ADAM-10 remained elevated. At 2 and 7 days, N-cadherin protein was below control. By the 15-day synapse stabilization phase, UEC N-cadherin rose above control, a shift not seen for TBI+BEC. At 7 days, increased TBI+BEC ADAM-10 transcript correlated with protein elevation. UEC ADAM-10 mRNA did not change, and no differences in MT5-MMP or N-cadherin mRNA were detected. Confocal imaging showed MT5-MMP, ADAM-10, and N-cadherin localization within reactive astrocytes. MMP inhibition attenuated ADAM-10 protein 15 days after TBI+BEC and increased N-cadherin. This inhibition partially restored long-term potentiation induction, but did not affect paired-pulse facilitation. Our results confirm time- and injury-dependent expression of MT5-MMP, ADAM-10, and N-cadherin during reactive synaptogenesis. Persistent ADAM-10 expression was correlated with attenuated N-cadherin level and reduced functional recovery. MMP inhibition shifted ADAM-10 and N-cadherin toward adaptive expression and improved synaptic function.

Elevation of Sema4A implicates Th cell skewing and the efficacy of IFN-β therapy in multiple sclerosis

Multiple sclerosis (MS) is a demyelinating autoimmune disease of the CNS and a leading cause of lasting neurologic disabilities in young adults. Although the precise mechanism remains incompletely understood, Ag presentation and subsequent myelin-reactive CD4(+) T cell activation/differentiation are essential for the pathogenesis of MS. Although semaphorins were initially identified as axon guidance cues during neural development, several semaphorins are crucially involved in various phases of immune responses. Sema4A is one of the membrane-type class IV semaphorins, which we originally identified from the cDNA library of dendritic cell (DC). Sema4A plays critical roles in T cell activation and Th1 differentiation during the course of experimental autoimmune encephalomyelitis, an animal model of MS; however, its pathological involvement in human MS has not been determined. In this study, we report that Sema4A is increased in the sera of patients with MS. The expression of Sema4A is increased on DCs in MS patients and shed from these cells in a metalloproteinase-dependent manner. DC-derived Sema4A is not only critical for Th1 but also for Th17 cell differentiation, and MS patients with high Sema4A levels exhibit Th17 skewing. Furthermore, patients with high Sema4A levels have more severe disabilities and are unresponsive to IFN-β treatment. Taken together, our results suggest that Sema4A is involved in the pathogenesis of MS by promoting Th17 skewing.

Neuronal brain-derived neurotrophic factor is synthesized in excess, with levels regulated by sortilin-mediated trafficking and lysosomal degradation

Brain-derived neurotrophic factor (BDNF) regulates neuronal differentiation, synaptic plasticity, and morphology, and modest changes in BDNF levels results in complex behavioral phenotypes. BDNF levels and intracellular localization in neurons are regulated by multiple mechanisms, including use of distinct promoters, mRNA and protein transport, and regulated cleavage of proBDNF to mature BDNF. Sortilin is an intracellular chaperone that binds to the prodomain of BDNF to traffic it to the regulated secretory pathway. However, sortilin binds to numerous ligands and plays a major role in mannose 6-phosphate receptor-independent transport of lysosomal hydrolases utilizing motifs in the intracellular domain that mediate trafficking from the Golgi and late endosomes. Sortilin is modified by ectodomain shedding, although the biological implications of this are not known. Here we demonstrate that ADAM10 is the preferred protease to cleave sortilin in the extracellular stalk region, to release the ligand binding sortilin ectodomain from the transmembrane and cytoplasmic domains. We identify sortilin shedding at the cell surface and in an intracellular compartment. Both sortilin and BDNF are trafficked to and degraded by the lysosome in neurons, and this is dependent upon the sortilin cytoplasmic tail. Indeed, expression of the sortilin ectodomain, which corresponds to the domain released after shedding, impairs lysosomal targeting and degradation of BDNF. These findings characterize the regulation of sortilin shedding and identify a novel mechanism by which sortilin ectodomain shedding acts as a regulatory switch for delivery of BDNF to the secretory pathway or to the lysosome, thus modulating the bioavailability of endogenous BDNF.

CD46 plasticity and its inflammatory bias in multiple sclerosis

Known as a link to the adaptive immune system, a complement regulator, a "pathogen magnet" and more recently as an inducer of autophagy, CD46 is the human receptor that refuses to be put in a box. This review summarizes the current roles of CD46 during immune responses and highlights the role of CD46 as both a promoter and attenuator of the immune response. In patients with multiple sclerosis (MS), CD46 responses are overwhelmingly pro-inflammatory with notable defects in cytokine and chemokine production. Understanding the role of CD46 as an inflammatory regulator is a distant goal considering the darkness in which its regulatory mechanisms reside. Further research into the regulation of CD46 expression through its internalization and processing will undoubtedly extend our knowledge of how the balance is tipped in favor of inflammation in MS patients.

Astrocyte proximity modulates the myelination gene fabric of oligodendrocytes

Extensive literature documented that astrocytes release neurotransmitters, cytokines and other signaling molecules to modulate migration, maturation and myelin synthesis of oligodendrocytes through mechanisms primarily converging on cytosolic [Ca2+] transients. Considering the long-term effects, it is expected that astrocyte-conditioned medium is a major regulator of gene expression in oligodendrocytes even in the absence of cytosol-to-cytosol communication via astrocyte-oligodendrocyte gap junction channels. Indeed, by comparing the transcriptomes of immortalized precursor oligodendrocyte (Oli-neu) cells when cultured alone and co-cultured with non-touching astrocytes we found profound changes in the gene expression level, control and networking. Remarkably, the astrocyte proximity was more effective in remodeling the myelination (MYE) gene fabric and its control by cytokine receptor (CYR)-modulated intercellular Ca2+-signaling (ICS) transcriptomic network than the dibutyryl-cAMP (db-cAMP) treatment-induced transformation into myelin-associated glycoprotein-positive oligodendrocyte-like cells. Moreover, astrocyte proximity up-regulated 37 MYE genes and switched on another 14 MYE, 23 ICS and 4 CYR genes, enhancing the roles of the leukemia inhibitory factor receptor and connexins Cx29 and Cx47. The novel prominent gene analysis identified the enhancer of zeste homolog 2 as the most relevant MYE gene in the astrocyte proximity, notch gene homolog 1 in control and B-cell leukemia/lymphoma 2 in differentiated Oli-neu cells.

ADAM-17: the enzyme that does it all

This review focuses on the role of ADAM-17 in disease. Since its debut as the tumor necrosis factor converting enzyme (TACE), ADAM-17 has been reported to be an indispensible regulator of almost every cellular event from proliferation to migration. The central role of ADAM-17 in cell regulation is rooted in its diverse array of substrates: cytokines, growth factors, and their receptors as well as adhesion molecules are activated or inactivated by their cleavage with ADAM-17. It is therefore not surprising that ADAM-17 is implicated in numerous human diseases including cancer, heart disease, diabetes, rheumatoid arthritis, kidney fibrosis, Alzheimer's disease, and is a promising target for future treatments. The specific role of ADAM-17 in the pathophysiology of these diseases is very complex and depends on the cellular context. To exploit the therapeutic potential of ADAM-17, it is important to understand how its activity is regulated and how specific organs and cells can be targeted to inactivate or activate the enzyme.

Involvement of ADAM10 in axonal outgrowth and myelination of the peripheral nerve

The disintegrin and metalloproteinase 10 (ADAM10) is a membrane-anchored metalloproteinase with both proteolytic and disintegrin characteristics. Here, we investigate the expression, regulation, and functional role of ADAM10 in axonal outgrowth and myelination of the peripheral nerve. Expression pattern analysis of 11 ADAM family members in co-cultures of rat dorsal root ganglia (DRG) neurons and Schwann cells (SCs) demonstrated the most pronounced mRNA expression for ADAM10. In further studies, ADAM10 was found to be consistently upregulated in DRG-SC co-cultures before the induction of myelination. Neurons as well as SCs widely expressed ADAM10 at the protein level. In neurons, the expression of ADAM10 was exclusively limited to the axons before the induction of myelination. Inhibition of ADAM10 activity by the hydroxamate-based inhibitors GI254023X and GW280264X resulted in a significant decrease in the mean axonal length. These data suggest that ADAM10 represents a prerequisite for myelination, although its activity is not required during the process of myelination itself as demonstrated by expression analysis of myelin protein zero (P0) and Sudan black staining. Hence, during the process of myelin formation, ADAM10 is highly upregulated and appears to be critically involved in axonal outgrowth that is a requirement for myelination in the peripheral nerve.

Up-regulation of soluble Axl and Mer receptor tyrosine kinases negatively correlates with Gas6 in established multiple sclerosis lesions

Multiple sclerosis is a disease that is characterized by inflammation, demyelination, and axonal damage; it ultimately forms gliotic scars and lesions that severely compromise the function of the central nervous system. Evidence has shown previously that altered growth factor receptor signaling contributes to lesion formation, impedes recovery, and plays a role in disease progression. Growth arrest-specific protein 6 (Gas6), the ligand for the TAM receptor tyrosine kinase family, consisting of Tyro3, Axl, and Mer, is important for cell growth, survival, and clearance of debris. In this study, we show that levels of membrane-bound Mer (205 kd), soluble Mer ( approximately 150 kd), and soluble Axl (80 kd) were all significantly elevated in homogenates from established multiple sclerosis lesions comprised of both chronic active and chronic silent lesions. Whereas in normal tissue Gas6 positively correlated with soluble Axl and Mer, there was a negative correlation between Gas6 and soluble Axl and Mer in established multiple sclerosis lesions. In addition, increased levels of soluble Axl and Mer were associated with increased levels of mature ADAM17, mature ADAM10, and Furin, proteins that are associated with Axl and Mer solubilization. Soluble Axl and Mer are both known to act as decoy receptors and block Gas6 binding to membrane-bound receptors. These data suggest that in multiple sclerosis lesions, dysregulation of protective Gas6 receptor signaling may prolong lesion activity.

Reduced neuronal co-localisation of nardilysin and the putative alpha-secretases ADAM10 and ADAM17 in Alzheimer's disease and Down syndrome brains

The peptidase nardilysin is involved in degradation of neuropeptides and limited intracellular proteolysis. Recent reports point to an involvement of nardilysin in the pathophysiology of Alzheimer's disease. Nardilysin enhances the alpha-secretase activity of the disintegrin and metalloproteases (ADAMs) 10 and 17, thereby possibly contributing to reduced generation of amyloidogenic fragments from the amyloid precursor protein. A prerequisite for the alpha-secretase-stimulating effect of nardilysin on the activity of ADAMs in vivo is cellular co-expression of nardilysin with ADAM10 and/or ADAM17. We immunolocalised nardilysin, ADAM10, and ADAM17 in cortical regions of normal aged brain, in Alzheimer's disease, and in Down syndrome brains and counted the number of protease-expressing neurons. A considerable portion of neurons co-express nardilysin together with either ADAM10 or ADAM17. Compared to controls, in Alzheimer's disease and in Down syndrome brains there is a decreased cellular expression of all three antigens, and a reduction in the number of those neurons that co-express nardilysin with ADAM10 or with ADAM17. Our data are consistent with the notion that the proposed alpha-secretase-enhancing activity of nardilysin might play a role in human brain pathology.

Interactions between APP secretases and inflammatory mediators

There is now a large body of evidence linking inflammation to Alzheimer's disease (AD). This association manifests itself neuropathologically in the presence of activated microglia and astrocytes around neuritic plaques and increased levels of inflammatory mediators in the brains of AD patients. It is considered that amyloid-β peptide (Aβ), which is derived from the processing of the longer amyloid precursor protein (APP), could be the most important stimulator of this response, and therefore determining the role of the different secretases involved in its generation is essential for a better understanding of the regulation of inflammation in AD. The finding that certain non-steroidal anti-inflammatory drugs (NSAIDs) can affect the processing of APP by inhibiting β- and γ-secretases, together with recent revelations that these enzymes may be regulated by inflammation, suggest that they could be an interesting target for anti-inflammatory drugs. In this review we will discuss some of these issues and the role of the secretases in inflammation, independent of their effect on Aβ formation.

The multiple sclerosis degradome: enzymatic cascades in development and progression of central nervous system inflammatory disease

An array of studies implicate different classes of protease and their endogenous inhibitors in multiple sclerosis (MS) pathogenesis based on expression patterns in MS lesions, sera, and/or cerebrospinal fluid (CSF). Growing evidence exists regarding their mechanistic roles in inflammatory and neurodegenerative aspects of this disease. Proteolytic events participate in demyelination, axon injury, apoptosis, and development of the inflammatory response including immune cell activation and extravasation, cytokine and chemokine activation/inactivation, complement activation, and epitope spreading. The potential significance of proteolytic activity to MS therefore relates not only to their potential use as important biomarkers of disease activity, but additionally as prospective therapeutic targets. Experimental data indicate that understanding the net physiological consequence of altered protease levels in MS development and progression necessitates understanding protease activity in the context of substrates, endogenous inhibitors, and proteolytic cascade interactions, which together make up the MS degradome. This review will focus on evidence regarding the potential physiologic role of those protease families already identified as markers of disease activity in MS; that is, the metallo-, serine, and cysteine proteases.

Microparticles of human atherosclerotic plaques enhance the shedding of the tumor necrosis factor-alpha converting enzyme/ADAM17 substrates, tumor necrosis factor and tumor necrosis factor receptor-1

Human atherosclerotic plaques express the metalloprotease tumor necrosis factor (TNF)-alpha converting enzyme (TACE/ADAM-17), which cleaves several transmembrane proteins including TNF and its receptors (TNFR-1 and TNFR-2). Plaques also harbor submicron vesicles (microparticles, MPs) released from plasma membranes after cell activation or apoptosis. We sought to examine whether TACE/ADAM17 is present on human plaque MPs and whether these MPs would affect TNF and TNFR-1 cellular shedding. Flow cytometry analysis detected 12,867 +/- 2007 TACE/ADAM17(+) MPs/mg of plaques isolated from 25 patients undergoing endarterectomy but none in healthy human internal mammary arteries. Plaque MPs harbored mainly mature active TACE/ADAM17 and dose dependently cleaved a pro-TNF mimetic peptide, whereas a preferential TACE/ADAM17 inhibitor (TMI-2) and recombinant TIMP-3 prevented this cleavage. Plaque MPs increased TNF shedding from the human cell line ECV-304 overexpressing TNF (ECV-304(TNF)), as well as TNFR-1 shedding from activated human umbilical vein endothelial cells or ECV-304(TNF) cells, without affecting TNF or TNFR-1 synthesis. MPs also activated the shedding of the endothelial protein C receptor from human umbilical vein endothelial cells. All these effects were inhibited by TMI-2. The present study shows that human plaque MPs carry catalytically active TACE/ADAM17 and significantly enhance the cell surface processing of the TACE/ADAM17 substrates TNF, TNFR-1, and endothelial protein C receptor, suggesting that TACE/ADAM17(+) MPs could regulate the inflammatory balance in the culprit lesion.

ADAM proteins in the brain

ADAM proteins are a family of metalloproteinases with a disintegrin domain. They have proteolytic as well as adhesive functions and can be involved in cell fusion events. Some ADAM proteins are expressed in a highly tissue restricted fashion, whereas others are expressed quite ubiquitously. In the brain, ADAM proteins have a role in neural development, axon guidance and inflammatory responses. Although there may be some functional overlap, homozygous deletion of some ADAM genes in mice can have fatal consequences. The expression and possible role of ADAM proteins in the brain will be discussed.

Key feature of the catalytic cycle of TNF-alpha converting enzyme involves communication between distal protein sites and the enzyme catalytic core

Despite their key roles in many normal and pathological processes, the molecular details by which zinc-dependent proteases hydrolyze their physiological substrates remain elusive. Advanced theoretical analyses have suggested reaction models for which there is limited and controversial experimental evidence. Here we report the structure, chemistry and lifetime of transient metal-protein reaction intermediates evolving during the substrate turnover reaction of a metalloproteinase, the tumor necrosis factor-alpha converting enzyme (TACE). TACE controls multiple signal transduction pathways through the proteolytic release of the extracellular domain of a host of membrane-bound factors and receptors. Using stopped-flow x-ray spectroscopy methods together with transient kinetic analyses, we demonstrate that TACE's catalytic zinc ion undergoes dynamic charge transitions before substrate binding to the metal ion. This indicates previously undescribed communication pathways taking place between distal protein sites and the enzyme catalytic core. The observed charge transitions are synchronized with distinct phases in the reaction kinetics and changes in metal coordination chemistry mediated by the binding of the peptide substrate to the catalytic metal ion and product release. Here we report key local charge transitions critical for proteolysis as well as long sought evidence for the proposed reaction model of peptide hydrolysis. This study provides a general approach for gaining critical insights into the molecular basis of substrate recognition and turnover by zinc metalloproteinases that may be used for drug design.

The cell-specific expression of metalloproteinase-disintegrins (ADAMs) in inflammatory myopathies

Inflammatory cell invasion and cytokine activation are important steps in the pathogenesis of immune-mediated diseases of muscle. Metalloproteinase-disintegrins (ADAMs) are considered to play a critical role in leukocyte migration by promoting cellular adhesion, cleavage of molecules of the extracellular matrix and shedding of membrane bound cytokines. Here, we report the expression patterns of ADAM8, ADAM9, ADAM10, ADAM12, ADAM17 and ADAM19 in cultured human myoblasts and peripheral blood mononuclear cells (PBMCs) in vitro, as well as in biopsies from patients suffering from polymyositis (PM), dermatomyositis (DM), inclusion body myositis (IBM) and non-inflammatory controls. We observed an in vitro downregulation of the RNAs of ADAM10, ADAM17 and ADAM19 in myoblasts after stimulation with various pro- and anti-inflammatory mediators, whereas in PBMCs an RNA upregulation of ADAM9, ADAM10, ADAM17 and ADAM19 was detectable under identical conditions. In human muscle biopsies, invading CD3+ T lymphocytes expressed ADAM17 and ADAM19, whereas macrophages co-localized to ADAM8, as detected by immunohistochemistry. Transfection of PBMCs with ADAM19 single interfering RNA and incubation with a metalloproteinase inhibitor suggest proteolytic activity of ADAM19 and involvement in the shedding of tumor necrosis factor-alpha. No differences in the cellular expression profiles between PM, DM and IBM were found, whereas the sections from non-inflammatory controls did not reveal any positive immunoreactivity for ADAMs, except for ADAM10, which is localized exclusively to muscle fibres. Our results suggest that certain ADAMs are expressed by specific cell populations during the genesis of immune-mediated diseases of human muscle.

Metalloproteinases: mediators of pathology and regeneration in the CNS

The matrix metalloproteinases and related A disintegrin and metalloproteinase enzymes are implicated in various diseases of the nervous system. However, metalloproteinases are increasingly being recognized as having beneficial roles during nervous system development and following injury. This review discusses general principles that govern the expression of metalloproteinases in the nervous system and their detrimental outcomes. It then focuses on the roles of metalloproteinases and their mechanisms in regulating neurogenesis, myelin formation and axonal growth. It is clear that metalloproteinases are important determinants in enabling recovery from injury to the nervous system.

Upregulation of ADAM-17 expression in active lesions in multiple sclerosis

ADAM-17, a disintegrin and metalloproteinase, is the major proteinase responsible for the cleavage of membrane-bound tumour necrosis factor (TNF) as well as being an active sheddase of other cytokines, cytokine receptors, growth factors and adhesion molecules. TNF is a major proinflammatory cytokine that has been identified as having a pathogenic role in inflammatory diseases within the CNS including multiple sclerosis (MS). Here we report the cellular origin and distribution of ADAM-17 expression within clinically and neuropathologically confirmed MS and normal control white matter, assessed by immunohistochemistry, western blotting and PCR. ADAM-17 expression was associated with the blood vessel endothelium, activated macrophages/microglia and parenchymal astrocytes in MS white matter. Increased levels of ADAM-17 immunoreactivity were displayed in active lesions with evidence of recent myelin breakdown. Further studies into the functional role of ADAM-17 in the pathogenesis of MS and other inflammatory conditions are required.

The ADAMs family: coordinators of nervous system development, plasticity and repair

A disintegrin and metalloprotease (ADAM) transmembrane proteins have metalloprotease, integrin-binding, intracellular signaling and cell adhesion activities. In contrast to other metalloproteases, ADAMs are particularly important for cleavage-dependent activation of proteins such as Notch, amyloid precursor protein (APP) and transforming growth factor alpha (TGFalpha), and can bind integrins. Not surprisingly, ADAMs have been shown or suggested to play important roles in the development of the nervous system, where they regulate proliferation, migration, differentiation and survival of various cells, as well as axonal growth and myelination. On the eleventh anniversary of the naming of this family of proteins, the relatively unknown ADAMs are emerging as potential therapeutic targets for neural repair. For example, over-expression of ADAM10, one of the alpha-secretases for APP, can prevent amyloid formation and hippocampal defects in an Alzheimer mouse model. Another example of this potential neural repair role is the finding that ADAM21 is uniquely associated with neurogenesis and growing axons of the adult brain. This comprehensive review will discuss the growing literature about the roles of ADAMs in the developing and adult nervous system, and their potential roles in neurological disorders. Most excitingly, the expanding understanding of their normal roles suggests that they can be manipulated to promote neural repair in the degenerating and injured adult nervous system.

CXCL16 is elevated in the cerebrospinal fluid versus serum and in inflammatory conditions with suspected and proved central nervous system involvement

In neuro-inflammatory diseases, activated T cells are thought to drive the inflammatory process. In this study, we investigated the potential role of three T cell attracting chemokines (CK) in neuro-inflammation. For this purpose, we measured levels of CXCL16, CCL17 and CCL18 in matched serum and cerebrospinal fluid (CSF) samples of patients with different neurological diseases. Interestingly, CXCL16 levels were significantly elevated in the CSF and were higher in inflammatory disease than in controls, whereas CCL17 and CCL18 were absent in the CSF. CCL18 was only elevated in serum of SLE patients. These data suggest that attraction of activated memory type T cells by CXCL16 might play an important role in the orchestration of immune responses in the central nervous system.

TNF–α converting enzyme (TACE) protein expression in different clinical subtypes of multiple sclerosis

Tumor necrosis factor (TNF)-alpha converting enzyme (TACE, also called ADAM17) is a key sheddase that releases TNF-alpha from its inactive cell-bound precursor. TACE protein expression levels in peripheral blood mononuclear cells were measured by Western blot analysis in 20 healthy controls and 80 multiple sclerosis (MS) patients before and after treatment with IFNbeta [20 patients with primary progressive (PP) MS, 20 patients with secondary progressive (SP) MS, and 40 patients with relapsing- remitting (RR) MS (20 patients during clinical remission and 20 patients in relapse)]. TNF-alpha serum levels were also measured by enzyme-linked immunoassay in the MS patients and healthy controls. TACE protein expression levels were lower in healthy controls and PPMS patients compared with SPMS patients and RRMS patient during clinical remission. No differences in TACE protein levels were observed between RRMS patients in relapse and during remission. TACE protein levels were increased in PPMS patients treated with IFNbeta. Serum TNF-alpha levels were higher in RRMS patients in relapse compared with RRMS patients during remission, and positive and negative correlations were found between TACE protein expression and serum TNF-alpha levels in RRMS patients during relapse and during remission respectively. These findings point to different regulatory mechanisms of the TACE-TNF-alpha pathway in the clinical MS subtypes and expand the role of TACE in MS pathogenesis.

Transcriptional profiling of spinal cord injury-induced central neuropathic pain

Central neuropathic pain (CNP) is an important problem following spinal cord injury (SCI), because it severely affects the quality of life of SCI patients. As in the patient population, the majority of rats develop significant allodynia (CNP rats) after moderate SCI. However, about 10% of SCI rats do not develop allodynia, or develop significantly less allodynia than CNP rats (non-CNP rats). To identify transcriptional changes underlying CNP development after SCI, we used Affymetrix DNA microarrays and RNAs extracted from the spinal cords of CNP and non-CNP rats. DNA microarry analysis showed significantly increased expression of a number of genes associated with inflammation and astrocytic activation in the spinal cords of rats that developed CNP. For example, mRNA levels of glial fibrilary acidic protein (GFAP) and Aquaporin 4 (AQP4) significantly increased in CNP rats. We also found that GFAP, S100beta and AQP4 protein elevation persisted for at least 9 months throughout contused spinal cords, consistent with the chronic nature of CNP. Thus, we hypothesize that CNP development results, in part, from dysfunctional, chronically "over-activated" astrocytes. Although, it has been shown that activated astrocytes are associated with peripheral neuropathic pain, this has not previously been demonstrated in CNP after SCI.

Tumor necrosis factor-alpha-converting enzyme is expressed in the inflamed peripheral nervous system

Tumor necrosis factor-alpha (TNF-alpha) is considered to play a critical role in the pathogenesis of immune-mediated inflammatory demyelinating disorders of the peripheral nervous system (PNS). Processing of membrane-bound inactive pro-TNF-alpha into the active soluble cytokine is mediated by a sheddase, the so-called TNF-alpha-converting enzyme (TACE), a member of the A Disintegrin and Metalloproteinase (ADAM) family. We explored the expression of TACE (ADAM-17) in sciatic nerves from Lewis rats with experimental autoimmune neuritis (EAN), an animal model of the Guillain-Barré syndrome (GBS), an immune-mediated polyradiculoneuropathy. To extend our study to human disease, sural nerve biopsies from GBS patients were investigated by immunohistochemistry. In EAN, T lymphocytes could be defined as the cellular source of ADAM-17 with peak expression levels at maximum clinical disease severity. Similarly, in human sural nerves, ADAM-17-expressing T cells could be localized primarily within the epi- and perineurium, whereas in control sections from patients with non-inflammatory neuropathies, no expression could be depicted. Our findings indicate that ADAM-17 is upregulated during EAN and expressed in nerves of GBS patients and thus may contribute to the pathogenesis of inflammatory demyelination of the PNS.

ADAM-17 and TIMP3 protein and mRNA expression in spinal cord white matter of rats with acute experimental autoimmune encephalomyelitis

Tumour necrosis factor (TNF) is a major immunomodulatory and proinflammatory cytokine implicated in the pathogenesis of multiple sclerosis (MS) and the animal model experimental autoimmune encephalomyelitis (EAE). ADAM-17 cleaves membrane-bound TNF into its soluble form. The distribution and level of ADAM-17 expression within spinal cords of Lewis rats with EAE was investigated. ADAM-17 was associated with endothelial cells in the naïve and pre-disease spinal cords. In peak disease astrocytic and inflammatory cells expressed ADAM-17. Upregulation of ADAM-17 mRNA expression was coupled with a decrease in mRNA levels of its inhibitor TIMP3 suggesting a role for ADAM-17 in EAE pathogenesis.

Genetic association between polymorphisms in the ADAMTS14 gene and multiple sclerosis

ADAMTS14 is a novel member of the ADAMTS (a disintegrin-like and metalloproteinase domain with thrombospondin type 1 modules) metalloproteinase family which processes extracellular matrix proteins. In the present study we performed a comprehensive investigation of the ADAMTS14 as a candidate gene for susceptibility to multiple sclerosis (MS). Eight single nucleotide polymorphisms (SNPs) were analyzed in a case-control study of 287 patients with MS [192 with relapsing-remitting MS (RRMS) and 95 with primary-progressive MS (PPMS)], and 285 age- and sex-matched controls. Allele and genotype frequencies were compared between controls and the MS subgroups, and gene-based haplotypes were reconstructed by computational procedures. Pairwise linkage disequilibrium values (D') suggested that three locus pairs (SNPs 3 through 5) had alleles in strong disequilibrium and constituted a haplotype block spanning 14 kb. Overall comparisons of allele and genotype frequencies showed association for SNPs 3 and 6 with MS. Stratification of MS patients according to major clinical forms revealed an increased frequency of both allele C (p = 0.006) and CC homozygosity (p = 0.008) at SNP6 in RRMS patients compared with controls. PPMS was associated with allele A at SNP2 compared with RRMS (p = 0.003) and controls (p = 0.009), and with CG heterozygosity at SNP3 compared with controls (p = 0.005). Haplotype frequency comparisons showed significant association between PPMS and the AGGGC haplotype compared with controls (p = 0.0004), and negative association between RRMS and the GGAGT haplotype compared with controls (p = 0.0026). No association was detected between different genotypes and disease severity measured by the Multiple Sclerosis Severity Score (MSSS). These findings suggest a potentially important role for the ADAMTS14 gene in predisposition to MS.

ADAM9, ADAM10, and ADAM15 mRNA levels in the rat brain after kainic acid-induced status epilepticus

ADAM metalloprotease-disintegrins mediate cell adhesion, proteolytic processing, and signal transduction. In the present study, the mRNA levels of ADAM9, ADAM10, and ADAM15 were examined in rat brain after kainic acid (KA)-induced status epilepticus. ADAM9 and ADAM10 expression was induced in dentate gyrus of hippocampus. ADAM15 expression remained unchanged. The spatiotemporal expression of ADAM9 and ADAM10 suggests that their regulation after the KA-induced status epilepticus could be related to neuroprotection.