Fibrin – Fibrinogen scaffold structural modification by phytochemicals and phytoproteases contained in an aqueous extract of Ageratum conyzoides Linn.

Based on mechanisms of fibrin clot polymerization and dissolution, it is possible to modulate fibrin formation and removal. Ageratum conyzoides Linn. (Asteraceae) is an annual herb with a long history of traditional medicine. There is high variability in the secondary metabolites of this plant which include flavonoids, and these molecules belong to a class of serine proteases inhibitors. Several plant enzymes belonging to the classes of serine proteases were observed to be active on the cascade of coagulation pathways. The aim of this study was to observe if even Ageratum conyzoides Linn. aqueous leaves extract contained proteases which could structurally modify the fibrin clot formation. To prepare plant extracts, dry leaves of the plant were extracted with distilled water. Fibrin gels were prepared by mixtures containing fibrinogen and thrombin with or without extract. Fibrin networks were disrupted by a denaturation buffer. Samples were deposited in 8% polyacrylamide gel and Coomassie blue was used to reveal migration. Our extract contained phytochemicals class flavonoids which are thrombin inhibitors. But our results support the evidence that the same extract contained plant serine proteases, specifically a fibrinogenase which hydrolyzed fibrinogen but not like thrombin.Keywords: Fibrin/Fibrinogen, structural modification, Ageratum conyzoides Linn., phytoproteases.

An Emerging Role for Serine Protease Inhibitors in T Lymphocyte Immunity and Beyond

The serine proteases of T lymphocytes provide immunity to infection. Serine Proteases Inhibitors (serpins) control the recognition of antigen, effector function, and homeostatic control of T lymphocytes through the inhibition of serine protease targets. Serpins are important promoters of cellular viability through their inhibition of executioner proteases, which affects the survival and development of long-lived memory T cells. The potent antiapoptotic properties of serpins can also work against cellular immunity by protecting viruses and tumors from eradication by T lymphocytes. Recent insights from knockout mouse models demonstrate that serpins also are required for hematological progenitor cells and so are critical for the development of lineages other than T lymphocytes. Given the emerging role of serpins in multiple aspects of lymphocyte immunity and blood development, there is much potential for new therapeutic approaches based directly on serpins or knowledge gained from identifying their physiologically relevant protease targets.

Serine Proteases Degrade Airway Mucins in Cystic Fibrosis

ABSTRACTAirway mucins are the major molecular constituents of mucus. Mucus forms the first barrier to invading organisms in the airways and is an important defense mechanism of the lung. We confirm that mucin concentrations are significantly decreased in airway secretions of subjects with cystic fibrosis (CF) who have chronicPseudomonas aeruginosainfection. In sputum from CF subjects without a history ofP. aeruginosa, we found no significant difference in the mucin concentration compared to mucus from normal controls. We demonstrate that mucins can be degraded by synthetic human neutrophil elastase (HNE) andP. aeruginosaelastase B (pseudolysin) and that degradation was inhibited by serine proteases inhibitors (diisopropyl fluorophosphates [DFP], phenylmethylsulfonyl fluoride [PMSF], and 1-chloro-3-tosylamido-7-amino-2-heptanone HCl [TLCK]). The mucin concentration in airway secretions from CF subjects is similar to that for normal subjects until there is infection byP. aeruginosa, and after that, the mucin concentration decreases dramatically. This is most likely due to degradation by serine proteases. The loss of this mucin barrier may contribute to chronic airway infection in the CF airway.