Endothelial MT1-MMP targeting limits intussusceptive angiogenesis and colitis via TSP1/nitric oxide axis.

Pathological angiogenesis contributes to cancer progression and chronic inflammatory diseases. In inflammatory bowel disease, the microvasculature expands by intussusceptive angiogenesis (IA), a poorly characterized mechanism involving increased blood flow and splitting of pre-existing capillaries. In this report, mice lacking the protease MT1-MMP in endothelial cells (MT1iΔEC ) presented limited IA in the capillary plexus of the colon mucosa assessed by 3D imaging during 1% DSS-induced colitis. This resulted in better tissue perfusion, preserved intestinal morphology, and milder disease activity index. Combined in vivo intravital microscopy and lentiviral rescue experiments with in vitro cell culture demonstrated that MT1-MMP activity in endothelial cells is required for vasodilation and IA, as well as for nitric oxide production via binding of the C-terminal fragment of MT1-MMP substrate thrombospondin-1 (TSP1) to CD47/αvß3 integrin. Moreover, TSP1 levels were significantly higher in serum from IBD patients and in vivo administration of an anti-MT1-MMP inhibitory antibody or a nonamer peptide spanning the αvß3 integrin binding site in TSP1 reduced IA during mouse colitis. Our results identify MT1-MMP as a new actor in inflammatory IA and a promising therapeutic target for inflammatory bowel disease.

Damage of facial soft tissues as a result of being bitten by a dog.

UNLABELLED: Being bitten by a dog can have serious health effects. That is why, never underestimate even the smallest soft tissue injuries inflicted by aggressive animals. This incident may have an impact on the further condition of a patient. From our first aid will also depend the aesthetic and functional effect of the scar on the face. We should pay attention to the use of antibiotic prophylaxis. The aim of the study was to perform the analysis of the soft tissue bitten injuries made by dogs in patients treated in the years 2004­2009 in the Clinic of Cranio-Maxillo-Facial and Oncological Surgery in Lódz. The most frequent attacked areas were analyzed in the cases of single and multiple face wounds. The dependence of the dog attacks and the alcohol consumption by the victims. The use of an early antibiotic prophylaxis and the number of the infectious complications. MATERIAL AND METHODS: The material studied is a group of 26 patients, including 17 women and 9 men. In the majority patients were older than 20 years old. RESULTS: The analysis of our data shows that most of the victims were aged 19-30 and 51-60 years. 14 patients have been mutilated on one area of the face, the remaining patients at least two areas. Most injuries underwent upper or lower lip. In all cases, the initial supply has been applied to the wounds. Antibiotic prophylaxis was used in 23 patients. In one of the other three cases, patient who have not been applied to the prevention of complications in the form of phlegmon face. Half of the attack dogs have been known to the victims. All patients had implemented prevention of tetanus, or held-to-date vaccinations. In eight cases, patients reported that at the time of the event they were under the influence of alcohol. CONCLUSIONS: Primary supply of bitten wounds of face at the moment seems to be the standard. In our study, in cases where patients has been treated with an antibiotic, there was no case of infection in the wound. Late complication in the form of phlegmon occurred in one patient who had not used prophylaxis. As the most of the authors note lower lip is the most vulnerable for the bite in the case of adult people. Analysis of our data is consistent with these reports. It has also been found that people under the influence of alcohol are often attacked by unknown dogs.

Site-specific cellular functions of MT1-MMP.

The response to environmental cues such as inflammatory stimuli requires coordinated cellular functions. Certain proteins have functions on both sides of the plasma membrane to allow coordination between the extracellular and intracellular milieus. The membrane-anchored matrix metalloproteinase MT1-MMP is well positioned to sense and modify the extracellular environment by processing matrix components, transmembrane proteins and soluble factors. Recent findings show, however, that MT1-MMP also plays unexpected intracellular roles in macrophages through its location at the plasma membrane, the Golgi or the nucleus, impacting cell motility, metabolism and gene transcription. MT1-MMP is thus an example of the evolutionary diversification of protein function, allowing optimal coordination between extracellular stimuli and cellular responses. It remains to be determined whether these new MT1-MMP functions are specific to macrophages, professional phagocytes involved in inflammation, or are present in other inflammation-responsive cells. In this review, we will summarize these site-specific MT1-MMP functions in macrophages and comment on the possible conservation of these functions in endothelial cells.

The protease MT1-MMP drives a combinatorial proteolytic program in activated endothelial cells.

The mechanism by which proteolytic events translate into biological responses is not well understood. To explore the link of pericellular proteolysis to events relevant to capillary sprouting within the inflammatory context, we aimed at the identification of the collection of substrates of the protease MT1-MMP in endothelial tip cells induced by inflammatory stimuli. We applied quantitative proteomics to endothelial cells (ECs) derived from wild-type and MT1-MMP-null mice to identify the substrate repertoire of this protease in TNF-α-activated ECs. Bioinformatics analysis revealed a combinatorial MT1-MMP proteolytic program, in which combined rather than single substrate processing would determine biological decisions by activated ECs, including chemotaxis, cell motility and adhesion, and vasculature development. MT1-MMP-deficient ECs inefficiently processed several of these substrates (TSP1, CYR61, NID1, and SEM3C), validating the model. This novel concept of MT1-MMP-driven combinatorial proteolysis in angiogenesis might be extendable to proteolytic actions in other cellular contexts.

Inflammatory macrophages, and not only neutrophils, die by apoptosis during acute peritonitis.

The central paradigm says that during inflammation, after completing their function, granulocytes die apoptotically in periphery to avoid destruction of self-tissues. Here we aimed to investigate the kinetic aspect of inflammatory leukocyte apoptosis and verify whether apart from neutrophils also other inflammatory leukocytes numerously undergo apoptosis. We observed that in physiological conditions, less than 7% of either resident peritoneal macrophages or lymphocytes die apoptotically. The studies on a model of acute zymosan-induced peritoneal inflammation revealed that there are two waves of inflammatory leukocyte apoptosis. The first wave corresponds to the time of maximal neutrophil accumulation in peritoneum (6h) and the apoptotic death indeed concerns mostly neutrophils (over 30% of those cells), but also more macrophages die at this time (>10%). The second wave (at 3 days) concerns mostly macrophages (20% versus 3-6% for other populations) and coincides with the resolution of inflammation and the dominant presence of macrophages. In contrast, numbers of apoptotic T (1-3%) and B (approximately 5%) cells do not significantly change during the whole peritonitis. The two waves of apoptosis concur with an increase of caspase-8, -9 and -3 at the transcript and activity levels. The apoptosis inducer TNF-alpha is produced only during first hours while nitric oxide throughout all inflammation. Moreover, during the whole course of peritonitis the expression of pro-apoptotic Bax dominates over anti-apoptotic Bcl-2. In conclusion, we characterized kinetics of apoptotic death of inflammatory leukocytes during acute peritoneal inflammation and revealed that both phagocyte populations (neutrophils and macrophages) die numerously in peritoneum.

Altered apoptosis of inflammatory neutrophils in MMP-9-deficient mice is due to lower expression and activity of caspase-3.

Matrix metalloproteinase 9 (MMP-9) is a Zn(2+)-dependent endopeptidase that degrades some of the components of basement membranes and extracellular matrix and thus participates in leukocyte infiltration during inflammation. In a model of zymosan peritonitis, neutrophil infiltration in MMP-deficient (MMP-9(-/-)) mice was significantly weaker at the time of their maximal influx in wild-type mice (6h). However, during the late stages of peritonitis (24h) an extended accumulation of neutrophils was observed in MMP-9(-/-)versus the wild-type mice. Recently, we reported that the ratio of apoptosis of inflammatory leukocytes is impaired in MMP-9(-/-) mice during late peritonitis and the process depends on COX-1-driven PGE(2). Here we scrutinized the alterations in apoptotic mechanisms by comparisons between MMP-9(-/-) and the wild-type mice. Altered apoptosis occurred only during late (24h) peritonitis and concerned only neutrophils, and not macrophages, mast cells or lymphocytes. Furthermore, expression and activity of caspases was altered in MMP-9(-/-) animals, delayed for caspase-8 and -9, and decreased in the case of caspase-3. Also the expression of Bax/Bcl-2 proteins was changed in MMP-9(-/-) mice. These changes, and in particular the impaired neutrophil apoptosis and weaker caspase-3 activity, were restored by the selective COX-1 inhibition. We conclude that in mice lacking MMP-9 the enhanced COX-1-PGE(2) decreases caspase-3 expression and activity leading to impaired apoptosis of inflammatory neutrophils resulting in abnormal accumulation of the cells at the inflammatory focus. The data also reinforce the notion that MMP-9 is a key enzyme in neutrophil biology.