Circadian clock molecule REV-ERBα regulates lung fibrotic progression through collagen stabilization

A network of pro-inflammatory genes repressed by clock signalling in bronchial epithelium

Background

Circadian rhythms are biological cycles that regulate various physiological processes, including immune responses, tissue repair and oxidative stress. Previous studies indicated a role for distorted circadian signalling in COPD.

Methods

In this study, we performed an unbiased analysis of the gene network that coexpressed with circadian clock signalling in COPD using weighted gene coexpression network analysis on RNA sequencing data from bronchial brushes of COPD patients.

Results

We found that a large network of pro-inflammatory genes, including CXCL8, IL1B, IL1A, CSF1 and TGFB1, was inversely correlated with the expression of core clock genes in bronchial brushes of COPD patients. In contrast, genes that positively coexpressed with circadian clock signalling associated with ciliated cell differentiation. Furthermore, we found that both circadian clock genes and their coexpressed genes were differentially expressed in lung tissues of COPD patients compared with healthy smokers.

Conclusions

Our results provide an unbiased and comprehensive analysis of the gene expression network coexpressed with circadian clock signalling in bronchial epithelium. Our findings suggest an association between circadian clock signalling and enhanced inflammatory gene expression in COPD patients.

Circadian clock gene expression: a key player in inflammation underlying chronic lung disease?

The circadian clock genes might play a key role in regulating the pathophysiological processes underlying COPD. Their role in regulating pathophysiological processes in other chronic lung diseases is still unclear, but important to elucidate. https://bit.ly/4f3KXQk.

Combined therapy with pirfenidone and nintedanib counteracts fibrotic silicosis in mice

BACKGROUND AND PURPOSE

Pneumoconiosis, especially silicosis, is a prevalent occupational disease with substantial global economic implications and lacks a definitive cure. Both pneumoconiosis and idiopathic pulmonary fibrosis (IPF) are interstitial lung diseases, which share many common physiological characteristics. Because pirfenidone and nintedanib are approved to treat IPF, their potential efficacy as antifibrotic agents in advanced silicosis deserves further exploration. Thus, we aimed to evaluate the individual and combined effects of pirfenidone and nintedanib in treating advanced silicosis mice and elucidate the underlying mechanisms of their therapeutic actions via multiomics.

EXPERIMENTAL APPROACH

We administered monotherapy or combined therapy of pirfenidone and nintedanib, with low and high doses, in silicosis established after 6 weeks and evaluated lung function, inflammatory responses and fibrotic status. Additionally, we employed transcriptomic and metabolomic analyses to uncover the mechanisms underlying different therapeutic strategies.

KEY RESULTS

Both pirfenidone and nintedanib were effective in treating advanced silicosis, with superior outcomes observed in combination therapy. Transcriptomic and metabolomic analyses revealed that pirfenidone and nintedanib primarily exerted their therapeutic effects by modulating immune responses, signalling cascades and metabolic processes involving lipids, nucleotides and carbohydrates. Furthermore, we experimentally validated both monotherapy and combined therapy yielded therapeutic benefits through two common signalling pathways: steroid biosynthesis and purine metabolism.

CONCLUSION AND IMPLICATIONS

In conclusion, pirfenidone and nintedanib, either individually or in combination, demonstrate substantial potential in advanced silicosis. Furthermore, combined therapy outperformed monotherapy, even at low doses. These therapeutic benefits are attributed to their influence on diverse signalling pathways and metabolic processes.

Rev-erb-α antagonism in alveolar macrophages protects against pneumococcal infection in elderly mice

Circadian rhythms control the diurnal nature of many physiological, metabolic, and immune processes. We hypothesized that age-related impairments in circadian rhythms are associated with high susceptibility to bacterial respiratory tract infections. Our data show that the time-of-day difference in the control of Streptococcus pneumoniae infection is altered in elderly mice. A lung circadian transcriptome analysis revealed that aging alters the daily oscillations in the expression of a specific set of genes and that some pathways that are rhythmic in young-adult mice are non-rhythmic or time shifted in elderly mice. In particular, the circadian expression of the clock component Rev-erb-α and apelin/apelin receptor was altered in elderly mice. In young-adult mice, we discovered an interaction between Rev-erb-α and the apelinergic axis that controls host defenses against S. pneumoniae via alveolar macrophages. Pharmacological repression of Rev-erb-α in elderly mice resulted in greater resistance to pneumococcal infection. These data suggest the causative role of age-associated impairments in circadian rhythms on respiratory infections and have clinical relevance.

Light Exposure, Physical Activity, and Indigeneity Modulate Seasonal Variation in NR1D1 (REV-ERBα) Expression

Nuclear receptor subfamily 1 group D member 1 (NR1D1 or REV-ERBα) is a crucial element of the circadian clock's transcriptional and translational feedback loop. Understanding its expression in humans is critical for elucidating its role in circadian rhythms and metabolic processes, and in finding potential links to various pathologies. In a longitudinal survey, we examined REV-ERBα expression at 08:00 using a real-time polymerase chain reaction (qRT-PCR) in blood mononuclear cells from Arctic native and non-native residents during equinoxes and solstices. REV-ERBα expression exhibited a pronounced seasonality, peaking at the summer solstice, and reaching a nadir at the winter solstice in both natives and non-natives, with a relatively higher summer peak in natives. After adjusting for age, sex, and body mass index, the amount and timing of light exposure, the amount of physical activity, and indigeneity emerged as significant predictors of REV-ERBα expression.

SR9009 attenuates TGF-β1-induced renal fibrotic responses by inhibiting the NOX4/p38 signaling pathway in NRK-49F cells

The circadian clock protein reverse erythroblastosis virus (REV)-ERBα is implicated in the pathogenesis of various diseases, including cancer and myocardial infarction. Emerging evidence suggests that SR9009, an agonist of REV-ERBα, regulates multiple signaling molecules independent or dependent of REV-ERBα. However, the impact of SR9009 on renal fibrosis remains largely unevaluated. In this study, we investigated the effects of SR9009 on transforming growth factor (TGF)-β1-induced fibrotic responses and elucidated the mechanisms involved. Masson's trichome staining revealed that in the unilateral ureteral obstruction groups, there was a decrease in REV-ERBα expression, accompanied by increased levels of the profibrotic factor TGF-β1 and the fibrosis marker α-smooth muscle actin (α-SMA). REV-ERBα knockdown significantly increased α-SMA expression in NRK-49F cells. SR9009 significantly attenuated unilateral ureteral obstruction-induced fibrosis and TGF-β1-induced fibrotic responses in normal rat kidney fibroblasts (NRK-49F cells). Conversely, the REV-ERBα antagonist SR8278 did not affect TGF-β1-induced fibrotic responses. Mechanistic studies revealed that SR9009 significantly inhibited the phosphorylation of ERK and p38, concomitant with reduced α-SMA levels, suppressing TGF-β1-induced NADPH oxidase 4 (NOX4) mRNA expression in NRK-49F cells. Notably, SR9009 did not influence the expression of dual specificity phosphatase 4, which dephosphorylates MAPKs, including p38. Furthermore, REV-ERBα knockdown did not affect the ability of SR9009 to inhibit TGF-β1-induced fibrotic responses and NOX4 expression in NRK-49F cells. In conclusion, SR9009 exerts a protective role against renal fibrosis independent of REV-ERBα. Therefore, SR9009 is a promising therapeutic agent for the prevention and treatment of renal fibrosis associated with renal failure.

Nr1d1 inhibition mitigates intermittent hypoxia-induced pulmonary hypertension via Dusp1-mediated Erk1/2 deactivation and mitochondrial fission attenuation

Intermittent hypoxia (IH) precipitates pulmonary vasoconstriction, culminating in the onset of pulmonary hypertension (PH) among individuals afflicted with sleep apnea. While Nuclear receptor subfamily 1 group D member 1 (Nr1d1) is progressively recognized as pivotal regulator of cellular physiology, the role in the pathogenesis of IH-induced PH remains largely uncharted. The expression of Nr1d1 was examined in IH-induced rodent PH and in IH-treated PASMCs. To elucidate the contribution of Nr1d1 to the development of IH-induced PH, we employed siRNA to modulate Nr1d1 expression in vitro and employed serotype 1 adeno-associated virus (AAV1) in vivo. Nr1d1 levels were elevated in IH-induced rodents PH lung tissues and IH-treated PASMCs. Knocking down Nr1d1 by AAV1 effectively inhibited PH progression in chronic IH-induced PH models. Mechanistic investigations identified dual specificity phosphatase 1 (Dusp1), as a direct target that Nr1d1 trans-repressed, mediating Nr1d1's regulatory influence on Erk1/2/Drp1 signaling. Nr1d1 deficiency ameliorates mitochondrial dysfunction and fission by restoring Dusp1 dysregulation and Drp1 phosphorylation. Activation of Erk1/2 with PMA reversed the Dusp1-mediated regulation of Drp1 phosphorylation, indicating the involvement of the Erk1/2 pathway in Drp1 phosphorylation controlled by Dusp1. Meanwhile, intermittent hypoxia induced more severe PH in Dusp1 knockout mice compared with wild-type mice. Our data unveil a novel role for Nr1d1 in IH-induced PH pathogenesis and an undisclosed Nr1d1-Dusp1 axis in PASMCs mitochondrial fission regulation.

Environmental tobacco smoke exposure exaggerates bleomycin-induced collagen overexpression during pulmonary fibrogenesis

Environmental tobacco smoke (ETS) is known to cause lung inflammatory and injurious responses. Smoke exposure is associated with the pathobiology related to lung fibrosis, whereas the mechanism that ETS exposure augments pulmonary fibrogenesis is unclear. We hypothesized that ETS exposure could exacerbate fibrotic responses via collagen dynamic dysregulation and complement activation. C57BL/6J and p16-3MR mice were exposed to ETS followed by bleomycin administration. ETS exposure exacerbated bleomycin-induced collagen and lysyl oxidase overexpression in the fibrotic lesion. ETS exposure also led to augmented bleomycin-induced upregulation of C3 and C3AR, which are pro-fibrotic markers. Moreover, overexpressed collagens and C3 levels were highly significant in males than females. The old mice (17 months old) were exposed to ETS and treated with bleomycin to induce fibrogenesis which is considered as an aging-associated disease. Fewer gene and protein dysregulations trends were identified between ETS exposure with the bleomycin group and the bleomycin alone group in old mice. Based on our findings, we suggested that ETS exposure increases the risk of developing severe lung fibrotic responses via collagen overexpression and lysyl oxidase-mediated collagen stabilization in the fibrotic lesion, and potentially affected the complement system activation induced by bleomycin. Further, male mice were more susceptible than females during fibrogenesis exacerbation. Thus ETS and bleomycin induced lung fibrotic changes via collagen-lysyl oxidase in an age-dependent mechanism.

Circadian Rhythms in Cardiovascular Metabolism

Energetic demand and nutrient supply fluctuate as a function of time-of-day, in alignment with sleep-wake and fasting-feeding cycles. These daily rhythms are mirrored by 24-hour oscillations in numerous cardiovascular functional parameters, including blood pressure, heart rate, and myocardial contractility. It is, therefore, not surprising that metabolic processes also fluctuate over the course of the day, to ensure temporal needs for ATP, building blocks, and metabolism-based signaling molecules are met. What has become increasingly clear is that in addition to classic signal-response coupling (termed reactionary mechanisms), cardiovascular-relevant cells use autonomous circadian clocks to temporally orchestrate metabolic pathways in preparation for predicted stimuli/stresses (termed anticipatory mechanisms). Here, we review current knowledge regarding circadian regulation of metabolism, how metabolic rhythms are synchronized with cardiovascular function, and whether circadian misalignment/disruption of metabolic processes contribute toward the pathogenesis of cardiovascular disease.

Pulmonary Effects of Traumatic Brain Injury in Mice: A Gene Set Enrichment Analysis

Acute lung injury occurs in 20-25% of cases following traumatic brain injury (TBI). We investigated changes in lung transcriptome expression post-TBI using animal models and bioinformatics. Employing unilateral controlled cortical impact for TBI, we conducted microarray analysis after lung acquisition, followed by gene set enrichment analysis of differentially expressed genes. Our findings indicate significant upregulation of inflammation-related genes and downregulation of nervous system genes. There was enhanced infiltration of adaptive immune cells, evidenced by positive enrichment in Lung-Th1, CD4, and CD8 T cells. Analysis using the Tabula Sapiens database revealed enrichment in lung-adventitial cells, pericytes, myofibroblasts, and fibroblasts, indicating potential effects on lung vasculature and fibrosis. Gene set enrichment analysis linked TBI to lung diseases, notably idiopathic pulmonary hypertension. A Venn diagram overlap analysis identified a common set of 20 genes, with FOSL2 showing the most significant fold change. Additionally, we observed a significant increase in ADRA1A→IL6 production post-TBI using the L1000 library. Our study highlights the impact of brain trauma on lung injury, revealing crucial gene expression changes related to immune cell infiltration, cytokine production, and potential alterations in lung vasculature and fibrosis, along with a specific spectrum of disease influence.

Capsaicin ameliorate pulmonary fibrosis via antioxidant Nrf-2/ PPAR- γ pathway activation and inflammatory TGF-β1/ NF-κB/COX II pathway inhibition

Bleomycin is an effective antibiotic with a significant anticancer properties, but its use is limited due to its potential to induce dose-dependent pulmonary fibrosis. Therefore, this study aimed to assess the therapeutic potential of Capsaicin as an additional treatment to enhance patient tolerance to Bleomycin compared to the antifibrotic drug Pirfenidone. Pulmonary fibrosis was induced in rats through by a single intratracheal Bleomycin administration in day zero, followed by either Capsaicin or Pirfenidone treatment for 7 days. After the animals were sacrificed, their lungs were dissected and examined using various stains for macroscopic and histopathological evaluation. Additionally, the study assessed various antioxidant, anti-inflammatory, and antifibrotic parameters were assessed. Rats exposed to Bleomycin exhibited visible signs of fibrosis, histopathological alterations, increased collagen deposition, and elevated mucin content. Bleomycin also led to heightened increased inflammatory cells infiltration in the bronchoalveolar lavage, elevated fibrosis biomarkers such as hydroxyproline, alpha-smooth muscle actin (α-SMA) and transforming growth factor-beta (TGF-β1), increased inflammatory markers including tumor necrosis factor-alpha (TNF-α), interlukine-6 (Il-6), interlukine-1β (Il-1β) nuclear factor-kappa B (NF-κB), and Cyclooxygenase-2 (COX-2), and transforming growth factor-beta (TGF-β1),. Furthermore, it reduced the expression of peroxisome proliferator-activated receptor-gamma (PPAR-γ), increased oxidative stress biomarkers like nitric oxide (NO), malondialdehyde (MDA), myeloperoxidase (MPO) and protein carbonyl. Bleomycin also decreased the expression of nuclear factor erythroid 2-related factor 2 (Nrf-2), reduced glutathione (GSH), total antioxidant capacity, and the activities of catalase and superoxide dismutase (SOD). Treating the animals with Capsaicin and Pirfenidone following Bleomycin exposure resulted in improved lung macroscopic and microscopic characteristics, reduced collagen deposition (collagen I and collagen III) and mucin content, decreased inflammatory cell infiltration, lowered levels of hydroxyproline, α-SMA, and TGF-β1, decreased TNF-α, Il-6, Il-1β, NF-κB, and COX-2, increased PPAR-γ and Nrf-2 expression, and improvement improved in all oxidative stress biomarkers. In summary, Capsaicin demonstrates significant antifibrotic activity against Bleomycin-induced lung injury that may be attributed, at least in part, to the antioxidant and anti-inflammatory activities of Capsaicin mediated by upregulation of PPAR-γ and Nrf-2 expression and decreasing. TGF-β1, NF-κB and COX II proteins concentrations.

Mutations of the circadian clock genes Cry, Per, or Bmal1 have different effects on the transcribed and nontranscribed strands of cycling genes

One important goal of circadian medicine is to apply time-of-day dosing to improve the efficacy of chemotherapy. However, limited knowledge of how the circadian clock regulates DNA repair presents a challenge to mechanism-based clinical application. We studied time-series genome-wide nucleotide excision repair in liver and kidney of wild type and three different clock mutant genotypes (Cry1-/-Cry2-/-, Per1-/-Per2-/-, and Bmal1-/-). Rhythmic repair on the nontranscribed strand was lost in all three clock mutants. Conversely, rhythmic repair of hundreds of genes on the transcribed strand (TSs) persisted in the livers of Cry1-/-Cry2-/- and Per1-/-Per2-/- mice. We identified a tissue-specific, promoter element-driven repair mode on TSs of collagen and angiogenesis genes in the absence of clock activators or repressors. Furthermore, repair on TSs of thousands of genes was altered when the circadian clock is disrupted. These data contribute to a better understanding of the regulatory role of the circadian clock on nucleotide excision repair in mammals and may be invaluable toward the design of time-aware platinum-based interventions in cancer.

Targeting accelerated pulmonary ageing to treat chronic obstructive pulmonary disease-induced neuropathological comorbidities

Chronic obstructive pulmonary disease (COPD) is a major incurable health burden, ranking as the third leading cause of death worldwide, mainly driven by cigarette smoking. COPD is characterised by persistent airway inflammation, lung function decline and premature ageing with the presence of pulmonary senescent cells. This review proposes that cellular senescence, a state of stable cell cycle arrest linked to ageing, induced by inflammation and oxidative stress in COPD, extends beyond the lungs and affects the systemic circulation. This pulmonary senescent profile will reach other organs via extracellular vesicles contributing to brain inflammation and damage, and increasing the risk of neurological comorbidities, such as stroke, cerebral small vessel disease and Alzheimer's disease. The review explores the role of cellular senescence in COPD-associated brain conditions and investigates the relationship between cellular senescence and circadian rhythm in COPD. Additionally, it discusses potential therapies, including senomorphic and senolytic treatments, as novel strategies to halt or improve the progression of COPD.

A three-gene random forest model for diagnosing idiopathic pulmonary fibrosis based on circadian rhythm-related genes in lung tissue

BACKGROUND

The disorder of circadian rhythm could be a key factor mediating fibrotic lung disease Therefore, our study aims to determine the diagnostic value of circadian rhythm-related genes (CRRGs) in IPF.

METHODS

We retrieved the data on CRRGs from previous studies and the GSE150910 dataset. The participants from the GSE150910 dataset were divided into training and internal validation sets. Next, we used several various bioinformatics methods and machine learning algorithms to screen genes. Next, we identified SEMA5A, COL7A1, and TUBB3, which were included in the random forest (RF) diagnostic model. Finally, external validation was conducted on data retrieved from the GSE184316 datasets.

RESULTS

The results revealed that the RF diagnostic model could diagnose patients with IPF in the internal validation set with the area under the ROC curve (AUC) value of 0.905 and in the external validation with the AUC value of 0.767. Furthermore, real-time quantitative PCR and western blotting results revealed a significant decrease in SEMA5A (p < 0.05) expression level and an increase in COL7A1 and TUBB3 expression levels in TGF-β1-treated normal human lung fibroblasts.

CONCLUSION

We constructed an RF diagnostic model based on SEMA5A, COL7A1, and TUBB3 expression in lung tissue for diagnosing patients with IPF.

Hypoxia Induces Alterations in the Circadian Rhythm in Patients with Chronic Respiratory Diseases

The function of the circadian cycle is to determine the natural 24 h biological rhythm, which includes physiological, metabolic, and hormonal changes that occur daily in the body. This cycle is controlled by an internal biological clock that is present in the body's tissues and helps regulate various processes such as sleeping, eating, and others. Interestingly, animal models have provided enough evidence to assume that the alteration in the circadian system leads to the appearance of numerous diseases. Alterations in breathing patterns in lung diseases can modify oxygenation and the circadian cycles; however, the response mechanisms to hypoxia and their relationship with the clock genes are not fully understood. Hypoxia is a condition in which the lack of adequate oxygenation promotes adaptation mechanisms and is related to several genes that regulate the circadian cycles, the latter because hypoxia alters the production of melatonin and brain physiology. Additionally, the lack of oxygen alters the expression of clock genes, leading to an alteration in the regularity and precision of the circadian cycle. In this sense, hypoxia is a hallmark of a wide variety of lung diseases. In the present work, we intended to review the functional repercussions of hypoxia in the presence of asthma, chronic obstructive sleep apnea, lung cancer, idiopathic pulmonary fibrosis, obstructive sleep apnea, influenza, and COVID-19 and its repercussions on the circadian cycles.

Targeting Rev-Erbα to protect against ischemia-reperfusion-induced acute lung injury in rats

BACKGROUND

The dysregulation of local circadian clock has been implicated in the pathogenesis of a broad spectrum of diseases. However, the pathophysiological role of intrinsic circadian clocks Rev-Erbα in ischemia-reperfusion (IR)-induced acute lung injury (ALI) remains unclear.

METHODS

The IR-ALI model was established by subjecting isolated perfused rat lungs to 40 min of ischemia followed by 60 min of reperfusion. Rats were randomly assigned to one of six groups: control, control + SR9009 (Rev-Erbα agonist, 50 mg/kg), IR, and IR + SR9009 at one of three dosages (12.5, 25, 50 mg/kg). Bronchoalveolar lavage fluids (BALF) and lung tissues were obtained and analyzed. In vitro experiments utilized mouse lung epithelial cells (MLE-12) exposed to hypoxia-reoxygenation (HR) and pretreated with SR9009 (10 µM/L) and Rev-Erbα siRNA.

RESULTS

SR9009 exhibited a dose-dependent reduction in lung edema in IR-ALI. It significantly inhibited the production of TNF-α, IL-6, and CINC-1 in BALF. Moreover, SR9009 treatment restored suppressed IκB-α levels and reduced nuclear NF-κB p65 levels in lung tissues. In addition, a SR9009 mitigated IR-induced apoptosis and mitogen-activated protein kinase (MAPK) activation in injured lung tissue. Finally, treatment with Rev-Erbα antagonist SR8278 abolished the protective action of SR9009. In vitro analyses showed that SR9009 attenuated NF-κB activation and KC/CXCL-1 levels in MLE-12 cells exposed to HR, and these effects were significantly abrogated by Rev-Erbα siRNA.

CONCLUSIONS

The findings suggest that SR9009 exerts protective effects against IR-ALI in a Rev-Erbα-dependent manner. SR9009 may provide a novel adjuvant therapeutic approach for IR-ALI.

Untargeted Metabolomics Reveals Alterations of Rhythmic Pulmonary Metabolism in IPF

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive condition characterized by the impairment of alveolar epithelial cells. Despite continued research efforts, the effective therapeutic medication is still absent due to an incomplete understanding of the underlying etiology. It has been shown that rhythmic alterations are of significant importance in the pathophysiology of IPF. However, a comprehensive understanding of how metabolite level changes with circadian rhythms in individuals with IPF is lacking. Here, we constructed an extensive metabolite database by utilizing an unbiased reference system culturing with 13C or 15N labeled nutrients. Using LC-MS analysis via ESI and APCI ion sources, 1300 potential water-soluble metabolites were characterized and applied to evaluate the metabolic changes with rhythm in the lung from both wild-type mice and mice with IPF. The metabolites, such as glycerophospholipids and amino acids, in WT mice exhibited notable rhythmic oscillations. The concentrations of phospholipids reached the highest during the fast state, while those of amino acids reached their peak during fed state. Similar diurnal variations in the metabolite rhythm of amino acids and phospholipids were also observed in IPF mice. Although the rhythmic oscillation of metabolites in the urea cycle remained unchanged, there was a significant up-regulation in their levels in the lungs of IPF mice. 15N-ammonia in vivo isotope tracing further showed an increase in urea cycle activity in the lungs of mice with IPF, which may compensate for the reduced efficiency of the hepatic urea cycle. In sum, our metabolomics database and method provide evidence of the periodic changes in lung metabolites, thereby offering valuable insights to advance our understanding of metabolic reprogramming in the context of IPF.

Environmental tobacco smoke exposure exaggerates bleomycin- induced collagen overexpression during pulmonary fibrogenesis

Environmental tobacco smoke (ETS) is known to cause lung inflammatory and injurious responses. Smoke exposure is associated with the pathobiology related to lung fibrosis, whereas the mechanism by which ETS exposure augments lung fibrogenesis is unclear. We hypothesized that ETS exposure could exacerbate fibrotic responses via collagen dynamic dysregulation and complement activation. C57BL/6J and p16-3MR mice were exposed to ETS followed by bleomycin administration. ETS exposure exacerbated bleomycin-induced collagen and lysyl oxidase overexpression in the fibrotic lesion. ETS exposure also led to augmented bleomycin-induced upregulation of C3 and C3AR, which are pro-fibrotic markers. Moreover, overexpressed collagens and C3 levels were highly significant in males than females. The old mice (17 months old) were exposed to ETS and treated with bleomycin to induce fibrogenesis, since fibrogenesis is an aging-associated disease. Fewer gene and protein dysregulations trends were identified between ETS exposure with the bleomycin group and the bleomycin alone group in old mice. Based on our findings, we suggested that ETS exposure increases the risk of developing severe lung fibrotic responses via collagen overexpression and lysyl oxidase-mediated collagen stabilization in the fibrotic lesion. ETS exposure also potentially affected the complement system activation induced by bleomycin. Further, male mice were more susceptible than females during fibrogenesis exacerbation.

Lung mechanics showing sex-based differences and circadian time-of-day response to bleomycin-induced lung injury in mice

Idiopathic pulmonary fibrosis (IPF) is a progressive disease that impairs lung mechanical properties due to dysregulated extracellular matrix remodeling. Lung function assessment is an important physiological endpoint in the mouse model of pulmonary fibrosis (PF) that has gained a broader scientific acceptance in the field. IPF pathophysiology shows sex-based differences, disproportionately affecting more men compared to women. Prior reports suggest that the circadian clock is perturbed during the pathogenesis of PF. We have comprehensively assessed the sex-based differences and time-of-day response (at Zeitgeber time: ZT0/6:00 a.m. or ZT12/6 p.m.) in lung mechanics among sham (control) versus bleomycin (BLM)-challenged female and male (C57BL/6: WT) mice using Flexi-vent. BLM challenge altered lung function significantly in males in both total lung (reduced dynamic compliance, and increased resistance and elastance) as well as lung tissue-specific parameters (increased tissue elastance and tissue damping) but less pronounced in females. BLM-challenged mice showed a time-of-day response in lung function at ZT0 versus ZT12, which was pronounced in the ZT0 BLM group. Overall, these findings provide a comprehensive analysis of altered lung function in female and male mice and the time-of-day difference in lung function parameters following BLM-induced lung fibrosis.

Rev-erbα agonists suppresses TGFβ1-induced fibroblast-to-myofibroblast transition and pro-fibrotic phenotype in human lung fibroblasts

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease characterized by excessive scarring of the lungs that can lead to respiratory failure and death. Lungs of patients with IPF demonstrate excessive deposition of extracellular matrix (ECM) and an increased presence of pro-fibrotic mediators such as transforming growth factor-beta 1 (TGFβ1), which is a major driver of fibroblast-to-myofibroblast transition (FMT). Current literature supports that circadian clock dysfunction plays an essential role in the pathophysiology of various chronic inflammatory lung diseases such as asthma, chronic obstructive pulmonary disease, and IPF. The circadian clock transcription factor Rev-erbα is encoded by Nr1d1 that regulates daily rhythms of gene expression linked to immunity, inflammation, and metabolism. However, investigations into the potential roles of Rev-erbα in TGFβ-induced FMT and ECM accumulation are limited. In this study, we utilized several novel small molecule Rev-erbα agonists (GSK41122, SR9009, and SR9011) and a Rev-erbα antagonist (SR8278) to determine the roles of Rev-erbα in regulating TGFβ1-induced FMT and pro-fibrotic phenotypes in human lung fibroblasts. WI-38 cells were either pre-treated/co-treated with or without Rev-erbα agonist/antagonist along with TGFβ1. After 48 h, the following parameters were evaluated: secretion of COL1A1 (Slot-Blot analysis) and IL-6 (ELISA) into condition media, expressions of α-smooth muscle actin (αSMA: immunostaining and confocal microscopy), and pro-fibrotic proteins (αSMA and COL1A1 by immunoblotting), as well as gene expression of pro-fibrotic targets (qRT-PCR: Acta2, Fn1, and Col1a1). Results revealed that Rev-erbα agonists inhibited TGFβ1-induced FMT (αSMA and COL1A1), and ECM production (reduced gene expression of Acta2, Fn1, and Col1a1), and decreased pro-inflammatory cytokine IL-6 release. The Rev-erbα antagonist promoted TGFβ1-induced pro-fibrotic phenotypes. These findings support the potential of novel circadian clock-based therapeutics, such as Rev-erbα agonist, for the treatment and management of fibrotic lung diseases and disorders.