# Deciphering the role of p16INK4A+ fibroblasts in lung fibrosis

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA, SAN FRANCISCO · 2022 · $556,850

## Abstract

Project Summary/Abstract
Aging is one of the biggest risk factors for many chronic lung diseases, including idiopathic pulmonary fibrosis
(IPF). However, uncertainties remain as to how age-related processes contribute to the pathogenesis of IPF,
particularly in deciphering the cell types that might play a role in both aging and fibrotic transformation.
Senescence, a cellular state characterized by an irreversible cell cycle arrest and other morphologic
transformations, is thought to be a cellular phenotype that becomes increasingly prevalent in aged organs,
contributing to the decline in function over time. p16INK4A, a tumor suppressor, is one of the best-studied
biomarkers of senescent cells in vitro and in vivo. Numerous genetic models have been built to remove p16INK4A+
cells from tissues, demonstrating a functional role for these cells in promoting age-related pathologies such as
lung fibrosis. Despite the knowledge gained from strategies that remove p16INK4A+ cells, deletion of these cells
precludes the identification and functional characterization of p16INK4A+ cells in vivo, leaving a large gap in our
understanding of how senescent cells might behave in tissues rather than in a culture dish. To address this, we
constructed a novel genetic reporter of senescence by engineering an amplified fluorescent tag driven by
expression of p16INK4A (mouse referred to as INK4A H2B-GFP Reporter-In-Tandem, or INKBRITE) to isolate and
characterize p16INK4A+ cells in vivo and ex vivo. To our surprise, we were able to identify p16INK4A+ fibroblasts in
young and healthy lungs that contribute to scar-forming cells in areas of fibrotic remodeling. Furthermore,
p16INK4A+ cells are able to alter the epithelial progenitor microenvironment and alter stem cell regenerative
outcomes. This led us to the hypothesis that p16INK4A+ fibroblasts are capable of contributing to fibrosis by
forming scars and inducing an pathologic epithelial response, and the INKBRITE reporter could be leveraged as
a screening platform to identify compounds that more precisely target p16INK4A+ fibroblasts in vivo. Through the
use of single cell RNA sequencing, adoptive cell transfers, lineage tracing, high-content imaging, and various
methodologies outlined in this proposal, we aim to better define the cellular contribution of p16INK4A+ fibroblasts
to fibrotic transformation, and define agents that might better remove it from tissues.

## Key facts

- **NIH application ID:** 10340480
- **Project number:** 1R01HL160895-01
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
- **Principal Investigator:** Tien Peng
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $556,850
- **Award type:** 1
- **Project period:** 2022-02-01 → 2025-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10340480

## Citation

> US National Institutes of Health, RePORTER application 10340480, Deciphering the role of p16INK4A+ fibroblasts in lung fibrosis (1R01HL160895-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10340480. Licensed CC0.

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