Surgical Director, Lung Transplantation

Mechanisms of Primary Graft Dysfunction followingLung Transplantation

Ankit Bharat MD FACS

PRIMARY GRAFT DYSFUNCTION• Incidence >50-70%

• Occurs within first 24 hours following transplant

• Characterized by respiratory failure

• Leading cause of short-term mortality

• Predominant cause of chronic lung allograft rejection

CM

Neut

NETosis

Alveolus

Interstitium

NCM

NeutPGDComplementary role in

neutrophil trafficking

“Garden-variety” ischemia-reperfusion injury

Bharat & Kreisel, Annals Thor Surg, 2018

Col VKAT

Pre-existing Autoimmunity& Autoantibodies

Col VKAT

Col VKAT

(Sequestered lung-restricted antigens in native lungs)

Teff

ISCHEMIA-REPERFUSIONCHRONIC INFLAMMATION

PGD

(Sequestered self-antigensin allograft exposed to host immune system)

Bharat & Kreisel, Annals Thor Surg, 2018

Autoantibody-mediated rejection mimicking PGD

NEUTROPHIL INFILTRATION MEDIATES PGD

Kreisel D et al. J Clin Invest 2011;121:265–276.

PERFUSED HUMAN DONOR LUNGS CONTAIN MONOCYTES

Bharat et al, AJRCMB, Jan 2016

Zhikun et al, SCIENCE TM

Demonstration of non-classical nonocytes in the intravascular space of donor lungs

Human PGD

Depletion of donor NCM abrogates neutrophil recruitment and ameliorates PGD

Donor PBS-lip Donor Clo-lip Nr4a1-/- donors

Nonclassical Monocyte (NCM)

Ly6ClowCX3CR1HighCCR2-

Monocyte subsets in mice and humans

Classical Monocyte (CM)

CCR2+Ly6ChighCX3CR1low

Depletion of recipient’s classical monocytes impairs neutrophil extravasation

Control Depletion of host CM

Spleen serves as a reservoir for inflammatory host-derived classical monocytes

Gas exchange

IL-1β production by host classical monocyte is necessary for neutrophil extravasation

WT donor IL1-R KO donor

NCM

Donor NCM initiate PGD

• Strategies to deplete NCM in donor lung? Role of EVLP

• NCM damage-associated molecular patterns (DAMPs)- ? Reduce allograft tissue ischemia

EVLP for marginal donor lungs

Cypel, NEJM, 2011

Increased levels of NCM in donor lungs from TBI or ECD donors

P<0.001

Human Mouse models

Fernandez et al, Under review

Donor NCM are mobilized during EVLPP<0.001

Stone et al, JHLT, 2014

Increased allograft endothelial cell apoptosis with VA ECMO compared to VV ECMO

P<0.001

Nonclassical monocytes rapidly phagocytoseapoptotic endothelial cells in vitro

Cell Tracker Green

Cel

l Tra

cker

Red

81%19%

Confocal

9%91%

Confocal

Human NCMMurine NCM

Normal endothelial culture CMP-induced apoptosis

Bharat et al, JAMA Cardiology, 2016

Reducing lung allograft ischemia during PGD

Acknowledgments

Pulmonary MedicineGR Scott Budinger

Alexander MisharinChing-I Chen

Alexandra McQuattie-Pimentel

Flow Cytometry CoreSuchitra Swaminathan

Comprehensive Transplant CenterMichael Abecassis

Bharat LabMahzad Akbarpour

Stephen ChiuHaiying SunElena Susan

Sheng-Xian JiaQiang Wu

Kreisel LabWenjun

Jim Hsiao