Matrix metalloproteinases in Angiogenesis and Inflammation

Patrolling monocytes crawl on the vascular endothelium and are in charge of removing foreign agents. We have recently discovered that the absence of the protease MT4-MMP increases the number of patrolling monocytes surveying the inflamed endothelium and the phagocytosis by macrophages (Clemente et al., Nat Commun 2018). Our preliminary data point to MT4-MMP targeting as beneficial to eliminate bacterial pathogens. The TFM will focus on the following objectives:

1. Characterization of infectious burden in the lungs of MT4-MMP-deficient mice. Respiratory pathogens will be instilled intratracheally and bacteria burden quantitated at different time-points after infection in mice lacking MT4-MMP. Moreover, patrolling monocytes will be sorted from CX3CR1-GFP reporter mice and transferred to Nur77-null mice which lack these monocytes and respiratory infection tested at different time-points.  

2. Analysis of the mechanisms underlying the anti-infectious capacity of MT4-MMP-deficient patrolling monocytes. We will focus on analyzing: i) patrolling monocyte abundance in the lungs by flow cytometry; ii) cytokine and chemokine levels by arrays and qPCR; iii) proteomics of isolated patrolling monocytes; iv) patrolling monocyte crawling in explanted lungs by time-lapse microscopy; and v) phagocytosis in co-culture.

3. Implementation of strategies to inhibit MT4-MMP in respiratory infections. The effect of anti-MT4-MMP inhibitory antibodies will be tested in vivo during respiratory infection of wild-type mice and compared to isotype control.

We will use high-dimensional flow cytometry and sorting, confocal and time-lapse microscopy, 2D and 3D image analysis, proteomics, and genetic mouse models to pursue these goals. We finally intend to apply this knowledge to develop novel strategies to boost endogenous innate immune responses and improve current treatments of life-threatening respiratory infections.