A Redox-Shifted Fibroblast Subpopulation Emerges in the Fibrotic Lung.

Idiopathic pulmonary fibrosis (IPF) is an aggressive and thus far incurable disease, characterized by aberrant fibroblast-mediated extracellular matrix deposition. Our understanding of the disease etiology is incomplete; however, there is consensus that a reduction-oxidation (redox) imbalance plays a role. In this study we use the autofluorescent properties of two redox molecules, NAD(P)H and FAD, to quantify changes in their relative abundance in living lung tissue of mice with experimental lung fibrosis, and in freshly isolated cells from mouse lungs and humans with IPF. Our results identify cell population-specific intracellular redox changes in the lungs in experimental and human fibrosis. We focus particularly on redox changes within collagen producing cells, where we identified a bimodal distribution of NAD(P)H concentrations, establishing NAD(P)Hhigh and NAD(P)Hlow sub-populations. NAD(P)Hhigh fibroblasts exhibited elevated pro-fibrotic gene expression and decreased collagenolytic protease activity relative to NAD(P)Hlow fibroblasts. The NAD(P)Hhigh population was present in healthy lungs but expanded with time after bleomycin injury suggesting a potential role in fibrosis progression. We identified a similar increased abundance of NAD(P)Hhigh cells in freshly dissociated lungs of subjects with IPF relative to controls, and similar reductions in collagenolytic activity in this cell population. These data highlight the complexity of redox state changes in experimental and human pulmonary fibrosis and the need for selective approaches to restore redox imbalances in the fibrotic lung.

A redox-shifted fibroblast subpopulation emerges in the fibrotic lung.

Idiopathic pulmonary fibrosis (IPF) is an aggressive and thus far incurable disease, characterized by aberrant fibroblast-mediated extracellular matrix deposition. Our understanding of the disease etiology is incomplete; however, there is consensus that a reduction-oxidation (redox) imbalance plays a role. In this study we use the autofluorescent properties of two redox molecules, NAD(P)H and FAD, to quantify changes in their relative abundance in living lung tissue of mice with experimental lung fibrosis, and in freshly isolated cells from mouse lungs and humans with IPF. Our results identify cell population-specific intracellular redox changes in the lungs in experimental and human fibrosis. We focus particularly on redox changes within collagen producing cells, where we identified a bimodal distribution of NAD(P)H concentrations, establishing NAD(P)H high and NAD(P)H low sub-populations. NAD(P)H high fibroblasts exhibited elevated pro-fibrotic gene expression and decreased collagenolytic protease activity relative to NAD(P)H low fibroblasts. The NAD(P)H high population was present in healthy lungs but expanded with time after bleomycin injury suggesting a potential role in fibrosis progression. We identified a similar increased abundance of NAD(P)H high cells in freshly dissociated lungs of subjects with IPF relative to controls, and similar reductions in collagenolytic activity in this cell population. These data highlight the complexity of redox state changes in experimental and human pulmonary fibrosis and the need for selective approaches to restore redox imbalances in the fibrotic lung.

In vitro laboratory models of proliferative vitreoretinopathy.

Proliferative vitreoretinopathy (PVR), the most common cause of recurrent retinal detachment, is characterized by the formation and contraction of fibrotic membranes on the surface of the retina. There are no Food and Drug Administration (FDA)-approved drugs to prevent or treat PVR. Therefore, it is necessary to develop accurate in vitro models of the disease that will enable researchers to screen drug candidates and prioritize the most promising candidates for clinical studies. We provide a summary of recent in vitro PVR models, as well as avenues for model improvement. Several in vitro PVR models were identified, including various types of cell cultures. Additionally, novel techniques that have not been used to model PVR were identified, including organoids, hydrogels, and organ-on-a-chip models. Novel ideas for improving in vitro PVR models are highlighted. Researchers may consult this review to help design in vitro models of PVR, which will aid in the development of therapies to treat the disease.

Dopamine Receptor D1 Is Exempt from Transforming Growth Factor ß-Mediated Antifibrotic G Protein-Coupled Receptor Landscape Tampering in Lung Fibroblasts.

Pulmonary fibroblasts are the primary producers of extracellular matrix (ECM) in the lungs, and their pathogenic activation drives scarring and loss of lung function in idiopathic pulmonary fibrosis (IPF). This uncontrolled production of ECM is stimulated by mechanosignaling and transforming growth factor beta 1 (TGF-ß1) signaling that together promote transcriptional programs including Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ). G protein-coupled receptors (GPCRs) that couple to G α s have emerged as pharmacological targets to inactivate YAP/TAZ signaling and promote lung fibrosis resolution. Previous studies have shown a loss of expression of "antifibrotic GPCRs"-receptors that couple to G α s, in IPF patient-derived fibroblasts compared with non-IPF samples. Of the 14 G α s GPCRs we found to be expressed in lung fibroblasts, the dopamine receptor D1 (DRD1) was one of only two not repressed by TGF-ß1 signaling, with the ß2-adrenergic receptor being the most repressed. We compared the potency and efficacy of multiple D1 and ß2 receptor agonists +/- TGF-ß1 treatment in vitro for their ability to elevate cAMP, inhibit nuclear localization of YAP/TAZ, regulate expression of profibrotic and antifibrotic genes, and inhibit cellular proliferation and collagen deposition. Consistently, the activity of ß2 receptor agonists was lost, whereas D1 receptor agonists was maintained, after stimulating cultured lung fibroblasts with TGF-ß1. These data further support the therapeutic potential of the dopamine receptor D1 and highlight an orchestrated and pervasive loss of antifibrotic GPCRs mediated by TGF-ß1 signaling. SIGNIFICANCE STATEMENT: Idiopathic pulmonary fibrosis (IPF) is a deadly lung disease with limited therapies. GPCRs have emerged as a primary target for the development of novel antifibrotic drugs; however, a challenge to this approach is the dramatic changes in GPCR expression in response to profibrotic stimuli. Here, we investigate the impact of TGF-ß1 on the expression of antifibrotic GPCRs and show the D1 dopamine receptor expression is uniquely maintained in response to TGF-ß1, further implicating it as a compelling target to treat IPF.

Pim-1 kinase is a positive feedback regulator of the senescent lung fibroblast inflammatory secretome.

Cellular senescence is emerging as a driver of idiopathic pulmonary fibrosis (IPF), a progressive and fatal disease with limited effective therapies. The senescence-associated secretory phenotype (SASP), involving the release of inflammatory cytokines and profibrotic growth factors by senescent cells, is thought to be a product of multiple cell types in IPF, including lung fibroblasts. NF-κB is a master regulator of the SASP, and its activity depends on the phosphorylation of p65/RelA. The purpose of this study was to assess the role of Pim-1 kinase as a driver of NF-κB-induced production of inflammatory cytokines from low-passage IPF fibroblast cultures displaying markers of senescence. Our results demonstrate that Pim-1 kinase phosphorylates p65/RelA, activating NF-κB activity and enhancing IL-6 production, which in turn amplifies the expression of PIM1, generating a positive feedback loop. In addition, targeting Pim-1 kinase with a small molecule inhibitor dramatically inhibited the expression of a broad array of cytokines and chemokines in IPF-derived fibroblasts. Furthermore, we provide evidence that Pim-1 overexpression in low-passage human lung fibroblasts is sufficient to drive premature senescence, in vitro. These findings highlight the therapeutic potential of targeting Pim-1 kinase to reprogram the secretome of senescent fibroblasts and halt IPF progression.

Dopamine receptor signaling regulates fibrotic activation of retinal pigmented epithelial cells.

Retinal pigmented epithelial (RPE) cells play an important role in retinal fibrotic diseases such as proliferative vitreoretinopathy (PVR). The purpose of this study was to elucidate the involvement of dopamine receptor signaling in regulating the fibrotic activation of RPE cells. Dopamine receptor expression, the effect of dopamine on fibrotic activity, and dopamine production were measured in the human RPE cell line ARPE-19. The fibrotic activation of RPE cells was evaluated in response to treatments with selective dopamine receptor agonists and antagonists by measuring gene expression, migration, proliferation, and fibronectin deposition. DRD2 and DRD5 are the dominant dopaminergic receptors expressed in ARPE-19 cells and TGF-ß stimulation enhances the autocrine release of dopamine, which we show further exasperates fibrotic activation. Finally, treatment with D2 dopamine receptor antagonists or D5 dopamine receptor agonists inhibits profibrotic gene expression, migration, proliferation, and fibronectin deposition and thus may serve as effective mechanisms for treating retinal fibrosis including PVR.

Combined control of the fibroblast contractile program by YAP and TAZ.

Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) are transcription cofactors implicated in the contractile and profibrotic activation of fibroblasts. Fibroblast contractile function is important in alveologenesis and in lung wound healing and fibrosis. As paralogs, YAP and TAZ may have independent or redundant roles in regulating transcriptional programs and contractile function. Using IMR-90 lung fibroblasts, microarray analysis, and traction microscopy, we tested whether independent YAP or TAZ knockdown alone was sufficient to limit transcriptional activation and contraction in vitro. Our results demonstrate limited effects of knockdown of either YAP or TAZ alone, with more robust transcriptional and functional effects observed with combined knockdown, consistent with cooperation or redundancy of YAP and TAZ in transforming growth factor ß1 (TGFß1)-induced fibroblast activation and contractile force generation. The transcriptional responses to combined YAP/TAZ knockdown were focused on a relatively small subset of genes with prominent overrepresentation of genes implicated in contraction and migration. To explore potential disease relevance of our findings, we tested primary human lung fibroblasts isolated from patients with idiopathic pulmonary fibrosis and confirmed that YAP and TAZ combined knockdown reduced the expression of three cytoskeletal genes, ACTA2, CNN1, and TAGLN. We then compared the contribution of these genes, along with YAP and TAZ, to contractile function. Combined knockdown targeting YAP/TAZ was more effective than targeting any of the individual cytoskeletal genes in reducing contractile function. Together, our results demonstrate that YAP and TAZ combine to regulate a multigene program that is essential to fibroblast contractile function.

Safety of guidelines recommending live attenuated influenza vaccine for routine use in children and adolescents with asthma.

OBJECTIVE: Evaluate whether a guideline recommending Live Attenuated Influenza Vaccine (LAIV) for children 2 years and older with asthma increased risks for lower respiratory events (LREs), within 21 or 42 days of vaccination, as compared to standard guidelines to administer Inactivated Influenza Vaccine (IIV) in children with asthma. METHODS: This was a pre/post guideline retrospective cohort study of children ages 2-17 years with asthma and receiving one or more influenza vaccines in two large medical groups from 2007 to 2016. Both groups recommended IIV in the pre-period; in 2010, one group implemented a guideline recommending LAIV for all children, including those with asthma. Main outcomes were medically attended LREs within 21 and 42 days after influenza immunization. Analysis used a generalized estimating equation regression to estimate the ratio of rate ratios (RORs) comparing pre/post events between LAIV guideline and control group. RESULTS: The cohort included 7851 influenza vaccinations in 4771 children with asthma. Among patients in the LAIV guideline group, the proportion receiving LAIV increased from 23% to 68% post-guideline implementation, versus an increase from 7 to 11% in the control group. Age and baseline asthma severity adjusted ROR showed no increase in LREs, primarily asthma exacerbations, following implementation of the LAIV guideline: overall aROR (95% Confidence Interval): 0.74 (0.43-1.29) for LRE within 21 days of vaccination, 0.77 (0.53-1.14) for LRE within 42 days of vaccination. For the subset of children ages 2-4 years aROR: 0.92 (0.34-2.53) for LRE within 21 days of vaccination and 0.94 (0.49-1.82) for LRE within 42 days of vaccination; for children 5-18 years aROR (95% CI): 0.58 (0.26-1.30) for LRE within 21 days of vaccination and 0.67 (0.37-1.23) for LRE within 42 days. CONCLUSION: In a large cohort of children with asthma, a guideline recommending LAIV rather than IIV did not increase LREs following vaccination.