Abstract
Pathologically increased vascular permeability is an important dysfunction in the pathomechanism of life-threatening conditions, such as sepsis, ischemia/reperfusion, or hereditary angioedema (HAE), diseases accompanied by uncontrolled activation of the complement system. HAE for example is caused by the deficiency of C1-inhibitor (the main regulator of early complement activation), which leads to edematous attacks threatening with circulatory collapse. We have previously reported that endothelial cells become activated during HAE attacks. A natural target of C1-inhibitor is mannan-binding lectin-associated serine protease-1 (MASP-1), a multifunctional serine protease, which plays a key role in the activation of complement lectin pathway. We have previously shown that MASP-1 induces the pro-inflammatory activation of endothelial cells and in this study we investigated whether MASP-1 can directly affect endothelial permeability. All experiments were performed on human umbilical vein endothelial cells (HUVECs). Real-time micro electric sensing revealed that MASP-1 decreases the impedance of HUVEC monolayers and in a recently developed permeability test (XperT), MASP-1 dose-dependently increased endothelial paracellular transport. We show that protease activated receptor-1 mediated intracellular Ca2+-mobilization, Rho-kinase activation dependent myosin light chain (MLC) phosphorylation, cytoskeletal actin rearrangement, and disruption of interendothelial junctions are underlying this phenomenon. Furthermore, in a whole-transcriptome microarray analysis MASP-1 significantly changed the expression of 25 permeability-related genes in HUVECs—for example it up-regulated bradykinin B2 receptor expression. According to our results, MASP-1 has potent permeability increasing effects. During infections or injuries MASP-1 may help eliminate the microbes and/or tissue debris by enhancing the extravasation of soluble and cellular components of the immune system, however, it may also play a role in the pathomechanism of diseases, where edema formation and complement lectin pathway activation are simultaneously present. Our findings also raise the possibility that MASP-1 may be a promising target of anti-edema drug development.
Highlights
Mannan-binding lectin-associated serine protease-1 (MASP-1) is a multifunctional serine protease of complement and coagulation
Treating human umbilical vein endothelial cells (HUVECs) with 2 μM recombinant catalytic fragment of MASP-1 (rMASP-1) resulted in a sharp decline of impedance with a minimum at 15–20 min after treatment and an overall duration of approximately 1 h, around which impedance has stabilized at a level slightly under baseline (Figure 1)
Since protease activated receptors (PARs)-dependent cell activation accompanied by intracellular Ca2+ mobilization is an important step in permeability induction, we investigated the role of various PARs in the rMASP-1 triggered Ca2+ response in HUVECs using PARagonists and -antagonists
Summary
Mannan-binding lectin-associated serine protease-1 (MASP-1) is a multifunctional serine protease of complement and coagulation. MASP-1 is indispensable for the activation of the complement lectin pathway, circulating in a zymogen form in complex with pattern recognition molecules (PRMs) mannan binding lectin (MBL), ficolins or collectins, serin proteases MASP-2 and MASP-3, and non-catalytic proteins MAp19/MAP2 and Map44/MAP-1 [1, 2]. Being a promiscuous protease with a relatively large and open substrate-binding cleft [5], MASP-1 is capable of cleaving a great variety of substrates in- and outside the complement system. It can activate MASP3 and possibly contribute to alternative pathway activation [4, 6]. As we have shown previously, it can activate endothelial cells (ECs) [12, 13], triggering the production of interleukins IL-6 and IL-8 [14] and up-regulating endothelial E-selectin expression [15]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
