# Complement Induces Inflammasome Assembly in Human Endothelium: Mechanisms and Consequences for Graft Rejection

> **NIH NIH F30** · YALE UNIVERSITY · 2020 · $30,270

## Abstract

Solid organ transplantation, the best available treatment for end-stage kidney, liver, lung and heart
failure, may fail due to chronic immunological rejection, often taking the form of allograft vasculopathy. Allograft
vasculopathy results from recruitment to and activation within the graft vessel wall of IFN-γ-producing graft-
reactive host T cells by graft ECs. The development of donor specific antibodies (DSA) that recognize non-self
alleles of MHC molecules expressed by graft endothelial cells (ECs) and that fix complement is a major risk for
allograft vasculopathy. Complement enhances this process by activating immune functions of the ECs that
mediate both recruitment and activation of alloreactive T cells. Binding of high titer panel reactive antibody
(PRA) from allo-sensitized transplant candidates, used to model DSA, deposits complement membrane attack
complex (MAC) on human ECs, both in culture or in vessel grafts in immunodeficient mouse hosts, and
induces gene expression of adhesion molecules and chemokines in a manner dependent upon MAC
internalization and non-canonical NF-κB signaling. The mechanism(s) by which MAC potentiates T cell
activation, measured as effector memory T cell proliferation and cytokine production in vitro or augmented
vasculopathic changes in vivo is unknown. My preliminary data show that MAC induces formation of an active
inflammasome in ECs, a previously undescribed phenomenon. Activated caspase-1 in the inflammasome
processes pro-IL-1β to active IL-1β and mediates its release. Blocking caspase-1 activity or inhibiting IL-1
signaling with IL-1 receptor antagonist (IL-1Ra) blocks both downstream inflammatory gene expression in ECs
secondary to canonical NF-κB activation and also blocks the augmentation of allogeneic T cell response in
vitro. I hypothesize that complement activation of the inflammasome in ECs intensifies the host T cell response
to graft arterial ECs by increasing local production of IL-1, potentiating allograft vasculopathy. In Specific Aim
1, I will characterize the MAC-induced inflammasome and determine the mechanisms linking MAC to
inflammasome assembly. I will examine if kinases of non-canonical NF-κB signaling are linked to
inflammasome assembly or IL-1 mRNA and protein synthesis. In Specific Aim 2, I will investigate the biological
consequences of alloantibody-induced inflammasome activation in ECs on the alloreactive T cell response that
drives allograft vasculopathy. I will determine if this response is also MAC-dependent and if mature IL-1
released from MAC-induced inflammasomes acts on ECs, T cells or both. I will characterize IL-1 dependent
changes of the clonal repertoire and subsets of activated alloreactive effector memory T cells using TCR deep
sequencing and FACS-analytic phenotyping and the effect of IL-1Ra or caspase-1 inhibition on the alloreactive
T cell response in vitro using cultured human ECs. I will use well-developed humanized mouse models of
allograft vasculopathy to a...

## Key facts

- **NIH application ID:** 9922666
- **Project number:** 5F30AI138473-03
- **Recipient organization:** YALE UNIVERSITY
- **Principal Investigator:** Catherine Bingchan Xie
- **Activity code:** F30 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $30,270
- **Award type:** 5
- **Project period:** 2018-06-01 → 2022-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9922666

## Citation

> US National Institutes of Health, RePORTER application 9922666, Complement Induces Inflammasome Assembly in Human Endothelium: Mechanisms and Consequences for Graft Rejection (5F30AI138473-03). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/9922666. Licensed CC0.

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