# Pathways regulating profibrotic macrophages in a novel explant model of systemic sclerosis-associated interstitial lung disease

> **NIH NIH R21** · UNIVERSITY OF PITTSBURGH AT PITTSBURGH · 2024 · $199,496

## Abstract

Systemic sclerosis (SSc) is a complex disease involving multiple cell types, leading to a plethora of clinical
manifestations. SSc-associated interstitial lung disease (SSc-ILD) is currently the most lethal complication of
the disease. We have recently reported results of single cell RNA-sequencing (scRNA-seq) of lung explants
from patients with SSc-ILD, as well as from patients with idiopathic pulmonary fibrosis (IPF), showing
alterations in gene expression in fibroblast, macrophage (Mφ) and other populations associated with
disease. Although the cellular and molecular changes seen in IPF are largely paralleled in SSc-ILD, SSc-ILD
is not associated with any of the genetic markers of senescence seen in IPF. Instead, patients with SSc
harbor SNPs in genes involved in immune regulation, and develop autoantibodies against a select series of
autoantigens, implicating immune dysregulation. Thus, we hypothesize that immune and inflammatory cells
drive the pathological fibrosis seen in SSc-ILD and that inflammatory interleukins and cytokines activate
differentiation of myofibroblasts. Several cytokines have been implicated in SSc-ILD pathogenesis. Our and
other studies have implicated transforming growth factor-beta (TGF-b) and platelet derived growth factor
(PDGF) in SSc-fibrosis. Interleukin-6 inhibition is an approved for SSc therapy that appears to block Mφ
activation in the skin. Inhibition of IL-13 has recently shown promise as a therapeutic target and expansion of
profibrotic SPP1 Mφs suggest that IL-13 and CSF-1 might block fibrosis. Unfortunately, currently available
murine and in vitro models for SSc fall short of fully and accurately modeling the disease, and thus do not
permit convincing assessments for the roles of these and other soluble mediators in disease pathogenesis.
We propose to test the role of these cytokines in healthy control (HC) and SSc-ILD explant cultures. As
single cell studies of SSc-ILD explant lungs have led to many of our current insights, we propose that single
cell analyses of explant culture of SSc-ILD lungs will provide unprecedented insight into the cellular
interactions and soluble mediators that lead to lung fibrosis. In aim 1 we will refine explant culture
methodologies and examine the effect of the cytokines described above on HC lung cells in explant cultures.
We will compare the effect of these cytokines to the changes in gene expression by fibroblast and Mφ
populations seen in our previous scRNA-seq studies of SSc-ILD. In aim 2 we will establish the effect of
soluble mediators on SSc-ILD explant cells, in this case testing the effects of therapeutic interventions on
gene expression of SSc-ILD lung cell populations. In this setting we anticipate that blocking cytokines or their
receptors will normalize gene expression back toward scRNA-seq gene expression seen in HC lungs. We
anticipate that these studies will not only shed light on the role of these cytokines in disease pathogenesis
but also provide a tracta...

## Key facts

- **NIH application ID:** 10887841
- **Project number:** 1R21AR084251-01
- **Recipient organization:** UNIVERSITY OF PITTSBURGH AT PITTSBURGH
- **Principal Investigator:** ROBERT A. LAFYATIS
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $199,496
- **Award type:** 1
- **Project period:** 2024-09-06 → 2026-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10887841

## Citation

> US National Institutes of Health, RePORTER application 10887841, Pathways regulating profibrotic macrophages in a novel explant model of systemic sclerosis-associated interstitial lung disease (1R21AR084251-01). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10887841. Licensed CC0.

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