Biology subjects

Planer, J. D.

Publications and source records attributed to Planer, J. D..

2 recordsLinked to original sources

bioRxiv2023

Vascular Endothelial-derived SPARCL1 Exacerbates Viral Pneumonia Through Pro-Inflammatory Macrophage Activation

Inflammation upon infectious lung injury is a double-edged sword: while tissue-infiltrating immune cells and cytokines are necessary to control infection, these same factors often aggravate injury. Full appreciation of both the sources and targets of inflammatory mediators is required to facilitate strategies to maintain antimicrobial effects while minimizing off-target epithelial and endothelial damage. Recognizing that the vasculature is centrally involved in tissue responses to injury and infection, we observed that pulmonary capillary endothelial cells (ECs) exhibit dramatic transcriptomic changes upon influenza injury punctuated by profound upregulation of Sparcl1. Endothelial deletion and overexpression of SPARCL1 implicated this secreted matricellular protein in driving key pathophysiologic symptoms of pneumonia, which we demonstrate result from its effects on macrophage polarization. SPARCL1 induces a shift to a pro-inflammatory "M1-like" phenotype (CD86+CD206-), thereby increasing associated cytokine levels. Mechanistically, SPARCL1 acts directly on macrophages in vitro to induce the pro-inflammatory phenotype via activation of TLR4, and TLR4 inhibition in vivo ameliorates inflammatory exacerbations caused by endothelial Sparcl1 overexpression. Finally, we confirmed significant elevation of SPARCL1 in COVID-19 lung ECs in comparison with those from healthy donors. Survival analysis demonstrated that patients with fatal COVID-19 had higher levels of circulating SPARCL1 protein compared to those who recovered, indicating the potential of SPARCL1 as a biomarker for prognosis of pneumonia and suggesting that personalized medicine approaches might be harnessed to block SPARCL1 and improve outcomes in high-expressing patients.

immunology↗

bioRxiv2022

Hyperactive mTOR in Lung Mesenchyme Induces Endothelial Dysfunction and Pulmonary Vascular Remodeling

Pulmonary vascular remodeling is the key structural abnormality in pulmonary hypertension (PH). Mechanistic target of rapamycin (mTOR) has long been suspected to play a role in the development of pulmonary vascular remodeling. However, underlying cellular and molecular mechanisms leading to this pathophysiological condition remain incompletely understood. To elucidate the crosstalk between lung mesenchyme with activated mTOR and endothelial cells (ECs), we focused on a monogenic lung disease, pulmonary lymphangioleiomyomatosis (LAM). LAM is a progressive cystic lung disease caused by a mutational inactivation of tuberous sclerosis complex (TSC1/TSC2), which results in constitutive mTOR activation in mesenchymal LAM cells. ECs derived from LAM lung explants showed increased proliferation, migration, and defective angiogenesis compared to age- and sex-matched ECs from control human lung. In LAM cells, we found increased WNT2 ligand expression. We also identified corresponding Frizzled 4 (FZD) receptors on ECs isolated from distal LAM lung, suggesting cellular crosstalk between LAM cells and ECs. In endothelial-fibroblast cocultures, treatment of normal ECs with WNT2 ligands recapitulated LAM EC phenotype and morphology. We observed transcriptomic upregulation in metabolic, angiogenic and growth pathways in ECs of young mice, while 1-year-old Tsc2KO mice spontaneously developed pulmonary vascular remodeling with concurrent elevation in right ventricular systolic pressure. Our study demonstrates that LAM cells are not just a pathological mesenchymal cell state but a signaling hub that contributes to dysregulated cellular response in the surrounding vasculature, eventual pulmonary vascular remodeling and PH.

molecular biology↗