Asociación del polimorfismo 1G>2G de la MMP1 con calcificación de la válvula aórtica / The association of MMP1 1G>2G polymorphism with aortic valve calcification

Introducción: La causa más frecuente de estenosis aórtica es la acumulación activa de calcio en los velos valvulares, lo que conlleva graves consecuencias clínicas. Diversas metaloproteasas de matriz extracelular (MMPs) han sido implicadas en el desarrollo de esta enfermedad. Por ello, se estudió la posible asociación entre un polimorfismo funcional de MMP1 y la cantidad de calcio depositado en la válvula aórtica. Pacientes y métodos: Se incluyeron en el estudio 45 pacientes sometidos a reemplazo valvular. El contenido en calcio de los velos de las válvulas extraídas en la cirugía se determinó mediante microtomografía computarizada. De muestras de sangre periférica se extrajo ADN para genotipar el polimorfismo -1607 1G>2G de MMP1 por PCR y posterior digestión. Resultados: Se observaron diferencias significativas en el contenido en calcio de las válvulas aórticas en individuos con distintos genotipos de -1607 1G>2G (p=0,042). Así, los portadores del alelo 2G (en homocigosis o heterocigosis) presentan valores más altos de calcio medido tanto como DMO (p=0,004) como BV/TV (p=0,002). La asociación con BV/TV fue independiente del sexo, la edad, el grado de función renal y la anatomía de la válvula (p=0,02), y se observó también una tendencia con la DMO (p=0,07). Conclusión: La asociación entre el polimorfismo 1G>2G de MMP1 y el contenido en calcio de la válvula aórtica sugiere que el alelo 1G tendría un efecto protector ante el depósito de calcio. Estos resultados apoyarían la importancia de ampliar el estudio para confirmar si este polimorfismo se podría usar como un posible predictor del desarrollo de estenosis aórtica (AU)

Introduction: The most common cause of aortic stenosis is active calcium accumulation in the valve cusps, which implies serious clinical consequences. Various extracellular matrix metalloproteases (MMPs) have been implicated in the development of this disease. Therefore, the possible association between a functional MMP1 polymorphism and the amount of calcium deposited on the aortic valve is studied. Patients and methods: 45 patients undergoing valve replacement were included in the study. The calcium content in valve cusps removed during surgery was determined by computed micro-tomography. DNA was extracted from peripheral blood samples for genotyping the -1607 1G>2G polymorphism of MMP1 by PCR and subsequent digestion. Results: Significant differences were observed in the calcium content in aortic valves in individuals with different -1607 1G>2G genotypes (p=0.042). Thus, 2G allele carriers (homozygous or heterozygous) present higher calcium levels measured as BMD (p=0.004) as well as BV/TV (p=0.002). The association with BV/TV was independent of sex, age, degree of renal function and anatomy of the valve (p=0.02). BMD tendency (p=0.07) was also observed. Conclusion: The association between 1G>2G MMP1 polymorphism and calcium content of the aortic valve suggests that the 1G allele would have a protective effect against calcium deposits. These results support the importance of further study to confirm whether this polymorphism could be used as a possible predictor of aortic stenosis development (AU)

Deficiency of MMP17/MT4-MMP proteolytic activity predisposes to aortic aneurysm in mice.

RATIONALE: Aortic dissection or rupture resulting from aneurysm causes 1% to 2% of deaths in developed countries. These disorders are associated with mutations in genes that affect vascular smooth muscle cell differentiation and contractility or extracellular matrix composition and assembly. However, as many as 75% of patients with a family history of aortic aneurysms do not have an identified genetic syndrome. OBJECTIVE: To determine the role of the protease MMP17/MT4-MMP in the arterial wall and its possible relevance in human aortic pathology. METHODS AND RESULTS: Screening of patients with inherited thoracic aortic aneurysms and dissections identified a missense mutation (R373H) in the MMP17 gene that prevented the expression of the protease in human transfected cells. Using a loss-of-function genetic mouse model, we demonstrated that the lack of Mmp17 resulted in the presence of dysfunctional vascular smooth muscle cells and altered extracellular matrix in the vessel wall; and it led to increased susceptibility to angiotensin-II-induced thoracic aortic aneurysm. We also showed that Mmp17-mediated osteopontin cleavage regulated vascular smooth muscle cell maturation via c-Jun N-terminal kinase signaling during aorta wall development. Some features of the arterial phenotype were prevented by re-expression of catalytically active Mmp17 or the N-terminal osteopontin fragment in Mmp17-null neonates. CONCLUSIONS: Mmp17 proteolytic activity regulates vascular smooth muscle cell phenotype in the arterial vessel wall, and its absence predisposes to thoracic aortic aneurysm in mice. The rescue of part of the vessel-wall phenotype by a lentiviral strategy opens avenues for therapeutic intervention in these life-threatening disorders.

Matrix metalloproteinase 2 and membrane type 1 matrix metalloproteinase co-regulate axonal outgrowth of mouse retinal ganglion cells.

Restoration of correct neural activity following central nervous system (CNS) damage requires the replacement of degenerated axons with newly outgrowing, functional axons. Unfortunately, spontaneous regeneration is largely lacking in the adult mammalian CNS. In order to establish successful regenerative therapies, an improved understanding of axonal outgrowth and the various molecules influencing it, is highly needed. Matrix metalloproteinases (MMPs) constitute a family of zinc-dependent proteases that were sporadically reported to influence axon outgrowth. Using an ex vivo retinal explant model, we were able to show that broad-spectrum MMP inhibition reduces axon outgrowth of mouse retinal ganglion cells (RGCs), implicating MMPs as beneficial factors in axonal regeneration. Additional studies, using more specific MMP inhibitors and MMP-deficient mice, disclosed that both MMP-2 and MT1-MMP, but not MMP-9, are involved in this process. Furthermore, administration of a novel antibody to MT1-MMP that selectively blocks pro-MMP-2 activation revealed a functional co-involvement of these proteinases in determining RGC axon outgrowth. Subsequent immunostainings showed expression of both MMP-2 and MT1-MMP in RGC axons and glial cells. Finally, results from combined inhibition of MMP-2 and ß1-integrin were suggestive for a functional interaction between these molecules. Overall, our data indicate MMP-2 and MT1-MMP as promising axonal outgrowth-promoting molecules. Axonal regeneration in the central nervous system is lacking in adult mammals, thereby impeding recovery from injury to the nervous system. Matrix metalloproteinases (MMPs) constitute a family of zinc-dependent proteases that were sporadically reported to influence axon outgrowth. Inhibition of specific MMPs reduced neurite outgrowth from mouse retinal explants. Our data indicate MMP-2 and MT1-MMP as promising axonal outgrowth-promoting molecules and show a possible link between MMP-2 and ß1-integrin in axon outgrowth.

Membrane-type 6 matrix metalloproteinase regulates the activation-induced downmodulation of CD16 in human primary NK cells.

CD16 (FcγRIIIa), the low-affinity receptor for IgG, expressed by the majority of human NK cells, is a potent activating receptor that facilitates Ab-dependent cell-mediated cytotoxicity (ADCC). ADCC dysfunction has been linked to cancer progression and poor prognosis for chronic infections, such as HIV; thus, understanding how CD16 expression is regulated by NK cells has clinical relevance. Importantly, CD16 cell-surface expression is downmodulated following NK cell activation and, in particular, exposure to stimulatory cytokines (IL-2 or IL-15), likely owing to the action of matrix metalloproteinases (MMPs). In this article, we identify membrane-type 6 (MT6) MMP (also known as MMP25) as a proteinase responsible for CD16 downmodulation. IL-2-induced upregulation of MT6/MMP25 cell-surface expression correlates with CD16 downmodulation. MT6/MMP25, sequestered in intracellular compartments in unstimulated NK cells, translocates to the cell surface after stimulation; moreover, it polarizes to the effector-target cell interface of the CD16-mediated immunological synapse. siRNA-mediated disruption of MT6/MMP25 expression enhances the ADCC capacity of NK cells, emphasizing the important functional role of MT6/MMP25 in the regulation of ADCC activity. Thus, this study uncovers a previously unknown role of MT6/MMP25 in human NK cells, and suggests that inhibition of MT6/MMP25 activity could improve ADCC efficacy of therapeutically administered NK cells that require IL-2 for culture and expansion.

Membrane-type matrix metalloproteinases: key mediators of leukocyte function.

Leukocytes are major cellular effectors of the immune response. To accomplish this task, these cells display a vast arsenal of proteinases, among which, members of the MMP family are especially important. Leukocytes express several members of the MMP family, including secreted- and membrane-anchored MT- MMPs, which synergistically orchestrate an appropriate proteolytic reaction that ultimately modulates immunological responses. The MT-MMP subfamily comprises TM- and GPI-anchored proteinases, which are targeted to well-defined membrane microdomains and exhibit different substrate specificities. Whereas much information exists on the biological roles of secreted MMPs in leukocytes, the roles of MT-MMPs remain relatively obscure. This review summarizes the current knowledge on the expression of MT-MMPs in leukocyte and their contribution to the immune responses and to pathological conditions.

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.

Matrix metalloproteinases: their potential role in the pathogenesis of diabetic nephropathy.

Matrix metalloproteinases (MMPs), a family of proteinases including collagenases, gelatinases, stromelysins, matrilysins, and membrane-type MMPs, affect the breakdown and turnover of extracellular matrix (ECM). Moreover, they are major physiologic determinants of ECM degradation and turnover in the glomerulus. Renal hypertrophy and abnormal ECM deposition are hallmarks of diabetic nephropathy (DN), suggesting that altered MMP expression or activation contributes to renal injury in DN. Herein, we review and summarize recent information supporting a role for MMPs in the pathogenesis of DN. Specifically, studies describing dysregulated activity of MMPs and/or their tissue inhibitors in various experimental models of diabetes, including animal models of type 1 or type 2 diabetes, clinical investigations of human type 1 or type 2 diabetes, and kidney cell culture studies are reviewed.

MT4-(MMP17) and MT6-MMP (MMP25), A unique set of membrane-anchored matrix metalloproteinases: properties and expression in cancer.

The process of cancer progression involves the action of multiple proteolytic systems, among which the family of matrix metalloproteinases (MMPs) play a pivotal role. The MMPs evolved to accomplish their proteolytic tasks in multiple cellular and tissue microenvironments including lipid rafts by incorporation and deletions of specific structural domains. The membrane type-MMPs (MT-MMPs) incorporated membrane anchoring domains that display these proteases at the cell surface, and thus they are optimal pericellular proteolytic machines. Two members of the MT-MMP subfamily, MMP-17 (MT4-MMP) and MMP-25 (MT6-MMP), are anchored to the plasma membrane via a glycosyl-phosphatidyl inositol (GPI) anchor, which confers these enzymes a unique set of regulatory and functional mechanisms that separates them from the rest of the MMP family. Discovered almost a decade ago, the body of work on GPI-MT-MMPs today is still surprisingly limited when compared to other MT-MMPs. However, new evidence shows that the GPI-MT-MMPs are highly expressed in human cancer, where they are associated with progression. Accumulating biochemical and functional evidence also highlights their distinct properties. In this review, we summarize the structural, biochemical, and biological properties of GPI-MT-MMPs and present an overview of their expression and role in cancer. We further discuss the potential implications of GPI-anchoring for enzyme function. Finally, we comment on the new scientific challenges that lie ahead to better understand the function and role in cancer of these intriguing but yet unique MMPs.

Membrane-type matrix metalloproteinases and vascularization in human endometrium during the menstrual cycle.

Endometrial angiogenesis is essential for a vascularized receptive endometrium. Previously, we described that membrane type-3 metalloproteinase (MT3-MMP) is associated with endometrial angiogenesis in vitro. The association of MT-MMPs with endometrial angiogenesis in vivo is unknown. Therefore, this study analysed the presence of MT-MMPs in human endometrium and their correlation with neovascularization. RNA/protein expressions of the six MT-MMPs were determined in cultured endometrial cells. Vascularization parameters and MT-MMP expressions in vivo were evaluated by immunohistochemistry in serial endometrium sections. MT1-, MT2-, MT3- and MT4-MMP antigens were expressed in cultured endometrial endothelial cells. MT2-, MT3- and MT4-MMP were expressed by endothelium during the proliferative and secretory phase. Strikingly, these phases showed elevated vascularization, elevated total vascular surface in proliferative phases, elevated number of vessels in proliferative/late secretory phases and increased luminal surface in the proliferative phases. All MT-MMP antigens were expressed in various endometrial cell types in vivo, with decreased levels during the early secretory phase. In conclusion, all MT-MMPs are expressed in endometrium in a cycle-dependent pattern. The vascular expression of MT2-, MT3- and MT4-MMP correlated with angiogenic episodes of the cycle. Since MT2- and MT3-MMP are known to regulate tube formation, these findings support earlier in vitro data on the role of MT3-MMP in endometrial angiogenesis. Additionally, MT2-MMP appears to be associated with endometrial neovascularization also.