Increased lipocalin-2 expression in pulmonary inflammation and fibrosis

Introduction

Idiopathic Pulmonary Fibrosis (IPF) is a chronic, progressive interstitial lung disease with dismal prognosis. The underlying pathogenic mechanisms are poorly understood, resulting in a lack of effective treatments. However, recurrent epithelial damage is considered critical for disease initiation and perpetuation, via the secretion of soluble factors that amplify inflammation and lead to fibroblast activation and exuberant deposition of ECM components. Lipocalin-2 (LCN2) is a neutrophil gelatinase-associated lipocalin (NGAL) that has been suggested as a biomarker of kidney damage. LCN2 has been reported to modulate innate immunity, including the recruitment of neutrophils, and to protect against bacterial infections by sequestering iron.

Methods

In silico analysis of publicly available transcriptomic datasets; ELISAs on human IPF patients' bronchoalveolar lavage fluids (BALFs); bleomycin (BLM)-induced pulmonary inflammation and fibrosis and LPS-induced acute lung injury (ALI) in mice: pulmonary function tests, histology, Q-RT-PCR, western blot, and FACS analysis.

Results and discussion

Increased LCN2 mRNA expression was detected in the lung tissue of IPF patients negatively correlating with respiratory functions, as also shown for BALF LCN2 protein levels in a cohort of IPF patients. Increased Lcn2 expression was also detected upon BLM-induced pulmonary inflammation and fibrosis, especially at the acute phase correlating with neutrophilic infiltration, as well as upon LPS-induced ALI, an animal model characterized by neutrophilic infiltration. Surprisingly, and non withstanding the limitations of the study and the observed trends, Lcn2-/- mice were found to still develop BLM- or LPS-induced pulmonary inflammation and fibrosis, thus questioning a major pathogenic role for Lcn2 in mice. However, LCN2 qualifies as a surrogate biomarker of pulmonary inflammation and a possible indicator of compromised pulmonary functions, urging for larger studies.

Stepwise activities of mSWI/SNF family chromatin remodeling complexes direct T cell activation and exhaustion

Highly coordinated changes in gene expression underlie T cell activation and exhaustion. However, the mechanisms by which such programs are regulated and how these may be targeted for therapeutic benefit remain poorly understood. Here, we comprehensively profile the genomic occupancy of mSWI/SNF chromatin remodeling complexes throughout acute and chronic T cell stimulation, finding that stepwise changes in localization over transcription factor binding sites direct site-specific chromatin accessibility and gene activation leading to distinct phenotypes. Notably, perturbation of mSWI/SNF complexes using genetic and clinically relevant chemical strategies enhances the persistence of T cells with attenuated exhaustion hallmarks and increased memory features in vitro and in vivo. Finally, pharmacologic mSWI/SNF inhibition improves CAR-T expansion and results in improved anti-tumor control in vivo. These findings reveal the central role of mSWI/SNF complexes in the coordination of T cell activation and exhaustion and nominate small-molecule-based strategies for the improvement of current immunotherapy protocols.

Abstract 1794: Targeting mammalian SWI/SNF chromatin remodeling complexes to improve T cell-based cancer immunotherapies

T cell activation and exhaustion are associated with highly coordinated changes in gene expression and chromatin accessibility. While the contribution of key, state-specific transcription factors to these processes has been extensively explored, the role for chromatin regulatory complexes remains less clear. The mammalian SWI/SNF (mSWI/SNF) complexes are a diverse family of ATP-dependent remodeling complexes that regulate DNA accessibility and hence facilitate timely and appropriate gene expression. Recent genome-scale CRISPR screens have highlighted the involvement of mSWI/SNF complexes in the acquisition of divergent T cell states; however, the mechanisms by which these complexes regulate T cell activation and exhaustion and how such activities may be leveraged for therapeutic benefit remain poorly understood. Here, we developed an in vitro system to map chromatin-level changes occurring during acute and chronic TCR stimulation in human T cells and to investigate the contribution of the mSWI/SNF complexes throughout these processes. By gene expression and chromatin profiling, we show that our in vitro model closely recapitulates the T cell activation and exhaustion phenotypes observed in human tumors. We demonstrate that the mSWI/SNF complexes contribute to shaping the epigenome of T cells at different activation and exhaustion stages, directing subsequent changes in gene expression. Specifically, deletion of components demarcating the cBAF subcomplex within the mSWI/SNF family improves T cell survival and proliferation and leads to the down-regulation of exhaustion hallmarks. Notably, by using four different compounds that either degrade or inhibit the catalytic activity of SMARCA2 and SMARCA4, we demonstrate that mSWI/SNF disruption significantly increases human T cell fitness, decreases exhaustion and is associated to memory-like hallmarks in chronically stimulated human T cells. Finally, pharmacologic mSWI/SNF inhibition improves CAR-T fitness and expansion and results in improved anti-tumor control in vivo. These findings reveal a central role for mSWI/SNF complexes in the processes of T cell activation and exhaustion, and suggest SMARCA4/2 ATPase inhibitors and degraders as potential strategies to enhance current T-cell based cancer immunotherapies.

Citation Format: Elena Battistello, Kimberlee Hixon, Dawn E. Comstock, Clayton K. Collings, Xufeng Chen, Javier Rodriguez Hernaez, Soobeom Lee, Konstantinos Ntatsoulis, Annamaria Cesarano, Kathryn Hockemeyer, W. Nicholas Haining, Matthew T. Witkowski, Jun Qi, Aristotelis Tsirigos, Fabiana Perna, Ioannis Aifantis, Cigall Kadoch. Targeting mammalian SWI/SNF chromatin remodeling complexes to improve T cell-based cancer immunotherapies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1794.

Galectin-3 interferes with tissue repair and promotes cardiac dysfunction and comorbidities in a genetic heart failure model

Galectin-3, a biomarker for heart failure (HF), has been associated with myocardial fibrosis. However, its causal involvement in HF pathogenesis has been questioned in certain models of cardiac injury-induced HF. To address this, we used desmin-deficient mice (des-/-), a model of progressive HF characterized by cardiomyocyte death, spontaneous inflammatory responses sustaining fibrosis, and galectin-3 overexpression. Genetic ablation or pharmacological inhibition of galectin-3 led to improvement of cardiac function and adverse remodeling features including fibrosis. Over the course of development of des-/- cardiomyopathy, monitored for a period of 12 months, galectin-3 deficiency specifically ameliorated the decline in systolic function accompanying the acute inflammatory phase (4-week-old mice), whereas a more pronounced protective effect was observed in older mice, including the preservation of diastolic function. Interestingly, the cardiac repair activities during the early inflammatory phase were restored under galectin-3 deficiency by increasing the proliferation potential and decreasing apoptosis of fibroblasts, while galectin-3 absence modulated macrophage-fibroblast coupled functions and suppressed both pro-fibrotic activation of cardiac fibroblasts and pro-fibrotic gene expression in the des-/- heart. In addition, galectin-3 also affected the emphysema-like comorbid pathology observed in the des-/- mice, as its absence partially normalized lung compliance. Collectively galectin-3 was found to be causally involved in cardiac adverse remodeling, inflammation, and failure by affecting functions of cardiac fibroblasts and macrophages. In concordance with this role, the effectiveness of pharmacological inhibition in ameliorating cardiac pathology features establishes galectin-3 as a valid intervention target for HF, with additive benefits for treatment of associated comorbidities, such as pulmonary defects. Schematic illustrating top to bottom, the detrimental role of galectin-3 (Gal3) in heart failure progression: desmin deficiency-associated spontaneous myocardial inflammation accompanying cardiac cell death (reddish dashed border) is characterized by infiltration of macrophages (round cells) and up-regulation of Lgals3 (encoding secretable galectin-3, green) and detrimental macrophage-related genes (Ccr2 and Arg1). In this galectin-3-enriched milieu, the early up-regulation of profibrotic gene expression (Tgfb1, Acta2, Col1a1), in parallel to the suppression of proliferative activities and a potential of senescence induction by cardiac fibroblasts (spindle-like cells), collectively promote des-/- cardiac fibrosis and dysfunction establishing heart failure (left panel). Additionally, galectin-3+ macrophage-enrichment accompanies the development of emphysema-like lung comorbidities. In the absence of galectin-3 (right panel), the effect of macrophage-fibroblast dipole and associated events are modulated (grey color depicts reduced expression or activities) leading to attenuated cardiac pathology in the des-/-Lgals3-/- mice. Pulmonary comorbidities are also limited.

Commonalities Between ARDS, Pulmonary Fibrosis and COVID-19: The Potential of Autotaxin as a Therapeutic Target

Severe COVID-19 is characterized by acute respiratory distress syndrome (ARDS)-like hyperinflammation and endothelial dysfunction, that can lead to respiratory and multi organ failure and death. Interstitial lung diseases (ILD) and pulmonary fibrosis confer an increased risk for severe disease, while a subset of COVID-19-related ARDS surviving patients will develop a fibroproliferative response that can persist post hospitalization. Autotaxin (ATX) is a secreted lysophospholipase D, largely responsible for the extracellular production of lysophosphatidic acid (LPA), a pleiotropic signaling lysophospholipid with multiple effects in pulmonary and immune cells. In this review, we discuss the similarities of COVID-19, ARDS and ILDs, and suggest ATX as a possible pathologic link and a potential common therapeutic target.