Fibrinogenolytic and fibrinolytic activity of cell-associated plasmin

Crosstalk between the plasminogen/plasmin system and inflammation resolution

The plasminogen/plasmin (Plg/Pla) system, best known for its classical role in thrombolysis, has been recently highlighted as a regulator of other biological processes in mammals, including key steps involved in the resolution of inflammation. Inflammation resolution is a complex process coordinated by different cellular effectors, notably leukocytes, and active mediators, and is initiated shortly after the inflammatory response begins. Once the inflammatory insult is eliminated, an effective and timely engagement of proresolution programs prevents persistent inflammation, thereby avoiding excessive tissue damage, fibrosis, and the development of autoimmunity. Interestingly, recent studies demonstrate that Plg/Pla and their receptor, plasminogen receptor KT (Plg-RKT), regulate key steps in inflammation resolution. The number of studies investigating the involvement of the Plg/Pla system in these and other aspects of inflammation, including degradation of extracellular matrices, immune cell migration, wound healing, and skeletal growth and maintenance, highlights key roles of the Plg/Pla system during physiological and pathologic conditions. Here, we discuss robust evidence in the literature for the emerging roles of the Plg/Pla system in key steps of inflammation resolution. These findings suggest that dysregulation in Plg production and its activation plays a role in the pathogenesis of inflammatory diseases. Elucidating central mechanisms underlying the role of Plg/Pla in key steps of inflammation resolution either in preclinical models of inflammation or in human inflammatory conditions, can provide a rationale for the development of new pharmacologic interventions to promote resolution of inflammation, and open new pathways for the treatment of thromboinflammatory conditions.

Dendrobium officinale flos increases neurotrophic factor expression in the hippocampus of chronic unpredictable mild stress-exposed mice and in astrocyte primary culture and potentiates NGF-induced neuronal differentiation in PC12 cells

Dendrobium officinale flos (DOF) is the flower of Dendrobium officinale Kimura et Migo, which is usually regarded as a by-product of Dendrobii Offcinalis Caulis. Based on its use as an alternative medicine, we evaluated the antidepressant-like effect of DOF extracts on chronic, unpredictable, mild stress-induced, depression-like behaviour in mice and tested the effects of DOF on the regulation of neurotrophic factors in mouse astrocyte primary cultures and PC12 cell lines. Oral treatment with DOF ethanol extract (DOF-E) could alleviate depression-like behaviours in stress-exposed mice, as evidenced by increased sucrose consumption and decreased immobile time in a forced swim test. In the hippocampus, DOF extracts increased the expression of NGF and BDNF, both at the transcriptional and protein levels. In astrocytes, DOF-E increased the expression of NGF and BDNF via a cAMP-dependent mechanism and regulated plasminogen and matrix metallopeptidase 9 (MMP-9), which are related to the metabolic regulation of neurotrophic factors. In PC12 cells, DOF-E induced the expression of neurofilaments and potentiated the induction of neurite outgrowth upon treatment with a low dose of NGF. Based on these findings, DOF might be used as a supplement for antidepressant therapy in patients with depression.

Detection and Characterization of Bacterial Proteinases Using Zymography

Proteinases play a crucial role in invasion and pathogenesis of bacteria, especially the extracellular and membrane-bound forms. Analysis of these proteinases demands the isolation by retaining the enzymatic activity. The isolation procedures maintaining the native structure of the enzyme in its soluble form are also of extreme importance. The qualitative analyses of these proteinases are carried out by electrophoresis and zymography. Enzymatic characterization based on the effect of inhibitors and activators on gelatinase activity also can be assessed using this zymography. The membrane-bound proteinases can be isolated in their native and soluble form, still retaining the activity using 6-aminocaproic acid and sodium deoxycholate; the procedure of which is explained in this chapter.

Cloning of a fibrinolytic enzyme (subtilisin) gene from Bacillus subtilis in Escherichia coli

Several investigations are being pursued to enhance the efficacy and specificity of fibrinolytic therapy. In this regard, microbial fibrinolytic enzymes attracted much more medical interests during these decades. Subtilisin, a member of subtilases (the superfamily of subtilisin-like serine proteases) and also a fibrinolytic enzyme is quite common in Gram-positive bacteria, and Bacillus species stand out in particular, as many extracellular and even intracellular variants have been identified. In the present work, the subtilisin gene from Bacillus subtilis PTCC 1023 was cloned into the vector pET-15b and expressed in Escherichia coli strain BL21 (DE3). Total genomic DNA were isolated and used for PCR amplification of the subtilisin gene by means of the specific primers. SDS-PAGE and enzyme assay were done for characterizing the expressed protein. A ~1,100 bp of the structural subtilisin gene was amplified. The DNA and amino acid sequence alignments resulting from the BLAST search of subtilisin showed high sequence identity with the other strains of B. subtilis, whereas significantly lower identity was observed with other bacterial subtilisins. The recombinant enzyme had the same molecular weight as other reported subtilisins and the E. coli transformants showed high subtilisin activity. This study provides evidence that subtilisin can be actively expressed in E. coli. The commercial availability of subtilisin is of great importance for industrial applications and also pharmaceutical purposes as thrombolytic agent. Thus, the characterization of new recombinant subtilisin and the development of rapid, simple, and effective production methods are not only of academic interest, but also of practical importance.

Different inhibitors of plasmin differentially affect angiostatin production and angiogenesis

Plasmin is a broad-spectrum serine proteinase, which is presumed to cleave many extracellular proteins and affect angiogenesis. In the present work, we studied the effect of two different inhibitors of plasmin (epsilon-aminocaproic and alpha(2)-antiplasmin) on angiogenesis in vivo using the chicken embryo chorioallantoic membrane assay, and in vitro using human umbilical vein endothelial cells. Epsilon-aminocaproic acid inhibited, while alpha(2)-antiplasmin induced, angiogenesis, as well as human umbilical vein endothelial cell proliferation, migration and tube formation on matrigel in a dose-dependent manner. Since plasmin has been implicated in the production of angiostatin, we studied the effect of the two plasmin inhibitors on angiostatin protein amounts in the chicken embryo chorioallantoic membrane. In this tissue, the 38- and 45-kDa isoforms of angiostatin are differentially affected by the two inhibitors: epsilon-aminocaproic acid increased, while alpha(2)-antiplasmin decreased the amounts of both isoforms. These data suggest that plasmin may have an antiangiogenic role in vivo through generation of angiostatin. Moreover, plasmin inhibitors differentially affect in vivo angiogenesis, depending on the mechanism by which they inhibit plasmin activity.