PhD Scientific Days 2022

Translational Medicine III.

Detection of Macrophage Populations in Porcine Pulmonary Vessels

Text of the abstract

Introduction: Complement activation related pseudoallergy (CARPA) is a non-IgE mediated hypersensitivity reaction. It can be triggered by a variety of nanotechnology enhanced (liposomal, polymer-conjugated) and protein-based (antibodies, enzymes) drugs and its molecular and cellular mechanisms are still poorly understood. In the lung, the reaction is characterized by vasoconstriction and increased pulmonary arterial pressure, an effect that may be mediated by pulmonary intravascular macrophage (PIM) cells.
PIM cells are a CD163+/CD172+ macrophage population that are located in the luminal face of the vessel walls of the lungs of certain mammal species, imbedded between the endothelial cells. PIM are pro-inflammatory cells that may play an important role in the propagation of pulmonary vasoconstriction during pathological conditions such as CARPA reaction.
Aims: Understanding the role played by PIM cells in pulmonary vasoconstriction.
Methods: Pigs were treated with iv. heparin injection to prevent blood clotting and thereafter their lungs were removed. Blood vessels were prepared from the obtained lungs and fixated in PFA overnight. The detection of the peri- and intravascular macrophage cells was done with immunocytochemical staining using anti-CD163 and anti-CD172 primary antibodies. Confocal fluorescent microscopy and ImageJ software were used for imaging and quantification of macrophage populations.
Results: We have identified three zones in the blood vessel walls where different macrophage populations reside. CD163+/CD172+ cells were abundant in or just beneath the endothelial cells, these are the PIM cells. CD163-/CD172+ cells were distinctly visible in the tunica media, whereas in the adventitia CD163+/CD172dim cells were the most common macrophages.
Future directions: With the PIM cells and other macrophage populations characterized, in the next phase of the investigations clodronate containing SUV-type liposomes will be used to deplete the various macrophage populations, especially the PIM cells. By conducting experiments using myograph, we hope to uncover the extent of the role the PIM cells play in pulmonary vasoconstriction.
Funding: This study was supported by NKFIH K-125174, K-135683 and K-139230 as well as by 2020-1.1.6-JÖVŐ-2021-00010, TKP2021-EGA-25 and EFOP-3.6.3-VEKOP-16-2017-00009 grants.