Culture conditions differentially regulate the inflammatory niche and cellular phenotype of tracheobronchial basal stem cells.

Bronchial epithelial cells derived from the tracheobronchial regions of human airways (HBECs) provide a valuable in vitro model for studying pathological mechanisms and evaluating therapeutics. This cell population comprises a mixed population of basal cells (BCs), the predominant stem cell in airways capable of both self-renewal and functional differentiation. Despite their potential for regenerative medicine, BCs exhibit significant phenotypic variability in culture.

Targeting fibroblast-endothelial cell interactions in LAM pathogenesis using 3D spheroid models and spatial transcriptomics.

Lymphangioleiomyomatosis (LAM) is a progressive lung disease with limited treatments, largely because of an incomplete understanding of its pathogenesis. Lymphatic endothelial cells (LECs) invade LAM cell clusters, which include human melanoma black-45-positive epithelioid cells and smooth muscle α-actin-expressing LAM-associated fibroblasts (LAMFs). Recent evidence shows that LAMFs resemble cancer-associated fibroblasts, with LAMF-LEC interactions contributing to disease progression.

Culture Conditions Differentially Regulate the Inflammatory Niche and Cellular Phenotype of Tracheo-Bronchial Basal Stem Cells.

Human bronchial epithelial cells (HBECs) derived from the tracheo-bronchial regions of human airways provide an excellent model for studying pathological mechanisms and evaluating therapeutics in human airway cells. This cell population comprises a mixed population of basal cells (BCs), the predominant stem cell in airways capable of both self-renewal and functional differentiation. Despite their potential for regenerative medicine, BCs exhibit significant phenotypic variability in culture.

Targeting Fibroblast-Endothelial Interactions in LAM Pathogenesis: 3D Spheroid and Spatial Transcriptomic Insights for Therapeutic Innovation.

Lymphangioleiomyomatosis (LAM) is a progressive lung disease with limited treatments, largely due to an incomplete understanding of its pathogenesis. Lymphatic endothelial cells (LECs) invade LAM cell clusters, which include HMB-45-positive epithelioid cells and smooth muscle α-actin-expressing LAM-associated fibroblasts (LAMFs). Recent evidence shows that LAMFs resemble cancer-associated fibroblasts, with LAMF-LEC interactions contributing to disease progression.

TREM-1 is required for enhanced OpZ-induced superoxide generation following priming.

Inflammatory agents, microbial products, or stromal factors pre-activate or prime neutrophils to respond to activating stimuli in a rapid and aggressive manner. Primed neutrophils exhibit enhanced chemotaxis, phagocytosis, and respiratory burst when stimulated by secondary activating stimuli. We previously reported that Triggering Receptor Expressed on Myeloid cells-1 (TREM-1) mediates neutrophil effector functions such as increased superoxide generation, transepithelial migration, and chemotaxis.

TREM-1 regulates neutrophil chemotaxis by promoting NOX-dependent superoxide production.

Neutrophil migration across tissue barriers to the site of injury involves integration of complex danger signals and is critical for host survival. Numerous studies demonstrate that these environmental signals fundamentally alter the responses of extravasated or "primed" neutrophils. Triggering receptor expressed on myeloid cells 1 (TREM-1) plays a central role in modulating inflammatory signaling and neutrophil migration into the alveolar airspace.

RNA inhibitors of nuclear proteins responsible for multiple organ dysfunction syndrome.

The development of multiple organ dysfunction syndrome (MODS) following infection or tissue injury is associated with increased patient morbidity and mortality. Extensive cellular injury results in the release of nuclear proteins, of which histones are the most abundant, into the circulation. Circulating histones are implicated as essential mediators of MODS.

Endothelial CaMKII as a regulator of eNOS activity and NO-mediated vasoreactivity.

The multifunctional Ca2+/calmodulin-dependent protein kinase II (CaMKII) is a serine/threonine kinase important in transducing intracellular Ca2+ signals. While in vitro data regarding the role of CaMKII in the regulation of endothelial nitric oxide synthase (eNOS) are contradictory, its role in endothelial function in vivo remains unknown. Using two novel transgenic models to express CaMKII inhibitor peptides selectively in endothelium, we examined the effect of CaMKII on eNOS activation, NO production, vasomotor tone and blood pressure.

Cu,Zn-Superoxide Dismutase-Mediated Redox Regulation of Jumonji Domain Containing 3 Modulates Macrophage Polarization and Pulmonary Fibrosis.

M2 macrophages are implicated in the development of pulmonary fibrosis as they generate profibrotic signals. The polarization process, at least in part, is regulated by epigenetic modulation. Because Cu,Zn-superoxide dismutase-induced H2O2 can polarize macrophages to a profibrotic M2 phenotype, we hypothesized that modulation of the redox state of the cell is involved in the epigenetic modulation of the macrophage phenotype.

CaMKII inhibition in type II pneumocytes protects from bleomycin-induced pulmonary fibrosis by preventing Ca2+-dependent apoptosis.

The calcium and calmodulin-dependent kinase II (CaMKII) translates increases in intracellular Ca(2+) into downstream signaling events. Its function in pulmonary pathologies remains largely unknown. CaMKII is a well-known mediator of apoptosis and regulator of endoplasmic reticulum (ER) Ca(2+).

Targeting the isoprenoid pathway to abrogate progression of pulmonary fibrosis.

Fibrotic remodeling in lung injury is a major cause of morbidity. The mechanism that mediates the ongoing fibrosis is unclear, and there is no available treatment to abate the aberrant repair. Reactive oxygen species (ROS) have a critical role in inducing fibrosis by modulating extracellular matrix deposition.

Alternative activation of macrophages and pulmonary fibrosis are modulated by scavenger receptor, macrophage receptor with collagenous structure.

Alternative activation of alveolar macrophages is linked to fibrosis following exposure to asbestos. The scavenger receptor, macrophage receptor with collagenous structure (MARCO), provides innate immune defense against inhaled particles and pathogens; however, a receptor for asbestos has not been identified. We hypothesized that MARCO acts as an initial signaling receptor for asbestos, polarizes macrophages to a profibrotic M2 phenotype, and is required for the development of asbestos-induced fibrosis.

Modulation of the mevalonate pathway by akt regulates macrophage survival and development of pulmonary fibrosis.

Protein kinase B (Akt) is a key effector of multiple cellular processes, including cell survival. Akt, a serine/threonine kinase, is known to increase cell survival by regulation of the intrinsic pathway for apoptosis. In this study, we found that Akt modulated the mevalonate pathway, which is also linked to cell survival, by increasing Rho GTPase activation.

Mitochondrial-targeted antioxidant therapy decreases transforming growth factor-β-mediated collagen production in a murine asthma model.

Asthma is a disease of acute and chronic inflammation in which cytokines play a critical role in orchestrating the allergic inflammatory response. IL-13 and transforming growth factor (TGF)-β promote fibrotic airway remodeling, a major contributor to disease severity. Improved understanding is needed, because current therapies are inadequate for suppressing development of airway fibrosis.

Accelerated development of pulmonary fibrosis via Cu,Zn-superoxide dismutase-induced alternative activation of macrophages.

Macrophages not only initiate and accentuate inflammation after tissue injury, but they are also involved in resolution and repair. This difference in macrophage activity is the result of a differentiation process to either M1 or M2 phenotypes. M1 macrophages are pro-inflammatory and have microbicidal and tumoricidal activity, whereas the M2 macrophages are involved in tumor progression and tissue remodeling and can be profibrotic in certain conditions.

SP-1 regulation of MMP-9 expression requires Ser586 in the PEST domain.

Rac1, a small GTPase, regulates macrophage MMP (matrix metalloproteinase)-9 in an ERK (extracellular-signal-regulated kinase)- and SP (specificity protein)-1-dependent manner. SP-1 contains a PEST (Pro-Glu-Ser-Thr) domain that may modulate protein stability. We hypothesize that Thr578, Ser586 and/or Ser587 in the PEST domain are required for SP-1 stability and MMP-9 expression secondary to activation of ERK, a serine/threonine kinase.

Mitochondrial Rac1 GTPase import and electron transfer from cytochrome c are required for pulmonary fibrosis.

The generation of reactive oxygen species, particularly H(2)O(2), from alveolar macrophages is causally related to the development of pulmonary fibrosis. Rac1, a small GTPase, is known to increase mitochondrial H(2)O(2) generation in macrophages; however, the mechanism by which this occurs is not known. This study shows that Rac1 is localized in the mitochondria of alveolar macrophages from asbestosis patients, and mitochondrial import requires the C-terminal cysteine of Rac1 (Cys-189), which is post-translationally modified by geranylgeranylation.

Mitochondrial Cu,Zn-superoxide dismutase mediates pulmonary fibrosis by augmenting H2O2 generation.

The release of H(2)O(2) from alveolar macrophages has been linked to the development of pulmonary fibrosis, but little is known about its source or mechanism of production. We found that alveolar macrophages from asbestosis patients spontaneously produce high levels of H(2)O(2) and have high expression of Cu,Zn-superoxide dismutase (SOD). Because Cu,Zn-SOD is found in the mitochondrial intermembrane space (IMS), we hypothesized that mitochondrial Cu,Zn-SOD-mediated H(2)O(2) generation contributed to pulmonary fibrosis.

Rac1-mediated mitochondrial H2O2 generation regulates MMP-9 gene expression in macrophages via inhibition of SP-1 and AP-1.

Aberrant matrix deposition is a hallmark of pulmonary fibrosis and is characterized by an imbalance between matrix deposition and degradation. We have previously shown that mice harboring a conditional deletion of the GTP-binding protein, Rac1, in macrophages are protected from asbestos-induced pulmonary fibrosis. To investigate the contribution of aberrant matrix degradation, we addressed the role of Rac1 in regulating expression of macrophage-specific MMP-9 (matrix metalloproteinase-9).

Modulation of reactive oxygen species by Rac1 or catalase prevents asbestos-induced pulmonary fibrosis.

The release of reactive oxygen species (ROS) and cytokines by alveolar macrophages has been demonstrated in asbestos-induced pulmonary fibrosis, but the mechanism linking alveolar macrophages to the pathogenesis is not known. The GTPase Rac1 is a second messenger that plays an important role in host defense. In this study, we demonstrate that Rac1 null mice are protected from asbestos-induced pulmonary fibrosis, as determined by histological and biochemical analysis.

Regulation of fatty acid synthesis by farnesyl pyrophosphate.

Fatty acid biosynthesis is transcriptionally regulated by liver X receptor (LXR) and its gene target, sterol regulatory element binding protein-1c (SREBP-1c). LXR activation is induced by oxysterol end products of the mevalonate pathway and is inhibited by the upstream non-sterol isoprenoid, geranylgeranyl pyrophosphate (GGPP). Whether isoprenoids play a role in regulating the transcription of genes involved in fatty acid biosynthesis is unknown.

Liver-X-receptor-mediated increase in ATP-binding cassette transporter A1 expression is attenuated by fatty acids in CaCo-2 cells: effect on cholesterol efflux to high-density lipoprotein.

The effect of fatty acids on LXR (liver X receptors)-mediated enhancement of ABCA1 (ATP-binding cassette transporter A1) expression and cholesterol efflux was investigated in human intestinal cells CaCo-2. LXR activation by T0901317 increased basolateral cholesterol efflux to lipoprotein particles isolated at a density of 1.21 g/ml or higher.

Polyunsaturated fatty acids decrease the expression of sterol regulatory element-binding protein-1 in CaCo-2 cells: effect on fatty acid synthesis and triacylglycerol transport.

Regulation of sterol regulatory element-binding proteins (SREBPs) by fatty acid flux was investigated in CaCo-2 cells. Cells were incubated with 1 mM taurocholate with or without 250 microM 18:0, 18:1, 18:2, 20:4, 20:5 or 22:6 fatty acids. Fatty acid synthase (FAS) and acetyl-CoA carboxylase mRNA levels and gene and protein expression of SREBPs were estimated.

LXR/RXR activation enhances basolateral efflux of cholesterol in CaCo-2 cells.

Regulation of gene expression of ATP-binding cassette transporter (ABC)A1 and ABCG1 by liver X receptor/retinoid X receptor (LXR/RXR) ligands was investigated in the human intestinal cell line CaCo-2. Neither the RXR ligand, 9-cis retinoic acid, nor the natural LXR ligand 22-hydroxycholesterol alone altered ABCA1 mRNA levels. When added together, ABCA1 and ABCG1 mRNA levels were increased 3- and 7-fold, respectively.