Development of chronic lung injury and pulmonary fibrosis in mice following acute exposure to nitrogen mustard

Mechanisms of Apoptosis and Pulmonary Fibrosis Resulting From Sulfur Mustard-Induced Acute Pulmonary Injury in Rats

Sulfur mustard (SM) is a highly toxic bifunctional alkylating agent that inflicts severe damage on the respiratory tract. Although numerous studies have examined the mechanisms underlying SM-induced pulmonary injury, the exact pathways involved remain unclear. This study aims to investigate an acute pulmonary injury model, with SM administered as a single intraperitoneal injection (8 mg/kg) or single intratracheal instillation (2 mg/kg) at equal toxicity doses (1LD50). The results revealed that epithelial cells in the alveolar septa of the intraperitoneal SM group exhibited a significantly higher expression of apoptotic markers, including pro-apoptotic protein Bax, caspase-3, and caspase-9 proteins, than those in the tracheal SM group. Conversely, the expression of the anti-apoptotic protein Bcl-2 was significantly lower in the intraperitoneal SM group than in the tracheal SM group, as confirmed by TUNEL staining and immunohistochemical staining. The intraperitoneal SM group exhibited markedly higher expression of fibrosis-related proteins, including MMP-2, MMP-9, TIMP-1, TIMP-2, collagen type I, collagen type III, TGF-β1, and Smad7, than the tracheal SM group. These markers, detected through immunohistochemical immunolabeling, indicate a more significant fibrotic response in the intraperitoneal group. In summary, this study demonstrates that intraperitoneal exposure to SM results in increased apoptosis, elevated expression of pro-apoptotic proteins, and fibrosis-related proteins in the alveolar epithelial cells compared with intratracheal exposure, even at equivalent toxicity levels. Our findings highlight the suitability of the intraperitoneal route for further investigation and identify apoptotic and fibrosis-related proteins as potential targets for intervention in SM-induced pulmonary injury.

Combination of HSP90 Inhibitors and HSP70 Inducers Prevent Hydrochloric Acid-Induced Pulmonary Fibrosis in Rabbits

Combined therapies with Heat Shock Protein 90 (HSP90) inhibitors and Heat Shock Protein 70 (HSP70) inducers are gaining significant interest in cancer and cardiovascular research. Here, we tested the hypothesis that HSP90 inhibitors and HSP70 inducers, together, can block the development of pulmonary fibrosis. We exposed New Zealand White Rabbits to hydrochloric acid (HCl, 0.1 N, 1.5 mL/kg), one of the top five chemicals most commonly involved in accidental exposures and inhalation injuries worldwide, and treated animals with either the orally available HSP90 inhibitor TAS-116 (1.7 mg/kg 5x/week) or TAS-116 combined with the HSP70 inducer, geranylgeranyl acetone (GGA, 50 mg/kg, 3x/week). At 60 days post-HCl instillation, TAS and GGA treatment markedly reduced the degree of pulmonary fibrosis, lung dysfunction, and activation of profibrotic pathways. The use of HSP70 inducers may be a helpful tool to improve the profile of HSP90 inhibitors and reduce their minimal effective dose and side effects. Further investigation is required to explore the exact synergistic mechanism behind the antifibrotic profile of HSP90 inhibitors and HSP70 inducers.

Effect of mustard analogs on cytokine profile in rodents: A systematic review and meta-analysis

Mustard analogs (sulfur and nitrogen forms) are toxic agents that may damage immunity. This meta-analysis investigates the impact of mustard analogs on cytokine profiles in rodent models, emphasizing trends and inconsistencies observed in previous studies. A total of 21 relevant studies that evaluated the effect of mustard analogs on cytokines were screened. Data were extracted, and effect size and heterogeneity were assessed using random-effects models, Cochrane Q, and I2 statistics. The analysis revealed significant elevations in levels of IL-1α, IFN-ϒ, IL-1β, IL-6, and TNFα and a reduction in the level of IL-10 following mustard exposure. The subgroup analysis showed that sulfur mustard analogs increased IL-1β, IL-6, IFN-γ, and TNF-α levels, while IL-10 levels decreased. Nitrogen mustard analogs also elevated IL-1α, IL-1β, and IL-6. Short-term exposure increased most cytokines, with a decrease in IL-10. In the medium term, all cytokines were elevated except IL-10, which was reduced. Long-term exposure sustained higher levels of IL-1α and IL-6. Analysis of serum, plasma, and BALF samples confirmed significant rises in most cytokines, with IL-10 reduced. Injection routes consistently led to increased cytokines IL-1α, IL-1β, IL-6, IFN-γ, TNF-α and decreased IL-10, whereas vapor and liquid touch routes primarily increased IL-6. It is concluded that mustard analogs induce notable inflammatory responses in rodent models. Among these, sulfur mustard exhibits more extensive systemic effects compared to nitrogen mustard, resulting in more severe inflammation. Additionally, the route of administration substantially influences the severity of the inflammatory response. The exposure length and sample type also affect the cytokine levels, which may mandate the development of targeted treatments to counteract these effects.

A novel Non-rodent animal model of hydrochloric acid-induced acute and chronic lung injury

Hydrochloric acid is one of the most prevalent and hazardous chemicals. Accidental spills occur in industrial plants or during transportation. Exposure to HCl can induce severe health impairment, including acute and chronic pulmonary diseases. We have previously described the molecular, structural, and functional aspects of the development of chronic lung injury and pulmonary fibrosis caused by intratracheal instillation of HCl in mice. Although mouse models of human disease have many advantages, rodents are evolutionary far from human and exhibit significant anatomical and physiological differences. Genetic and anatomic similarities between rabbits and humans are significantly higher. Rabbit models of HCl-induced lung injury have been used sparsely to evaluate acute lung injury. In this study, for the first time, we utilized rabbits as a model of HCl-induced pulmonary fibrosis and chronic lung injury. We present molecular, histological, and functional evidence that demonstrate the utility of using this model for studying new pharmaceutics against pulmonary fibrosis.

A Novel Non-Rodent Animal Model of Hydrochloric Acid-Induced acute and chronic lung injury

Hydrochloric acid is one of the most prevalent and dangerous chemicals. Accidental spills occur in industrial plants or during transportation. Exposure to HCl can induce severe health impairment, including acute and chronic pulmonary diseases. We have previously described the molecular, structural, and functional aspects of the development of chronic lung injury and pulmonary fibrosis caused by intratracheal instillation of HCl in mice. Although mouse models of human disease have many advantages, rodents are evolutionary far from human and exhibit significant anatomical and physiological differences. Genetic and anatomic similarities between rabbits and humans are significantly higher. Rabbit models of HCl-induced lung injury have been used sparsely to evaluate acute lung injury. In this study, for the first time, we utilized rabbits as a model of HCl-induced pulmonary fibrosis and chronic lung injury. We present molecular, histological, and functional evidence that demonstrate the utility of using this model for studying new pharmaceutics against pulmonary fibrosis.

Identification of early events in nitrogen mustard pulmonary toxicity that are independent of infiltrating inflammatory cells using precision cut lung slices

Nitrogen mustard (NM; mechlorethamine) is a cytotoxic vesicant known to cause acute lung injury which can progress to chronic disease. Due to the complex nature of NM injury, it has been difficult to analyze early responses of resident lung cells that initiate inflammation and disease progression. To investigate this, we developed a model of acute NM toxicity using murine precision cut lung slices (PCLS), which contain all resident lung cell populations. PCLS were exposed to NM (1-100 μM) for 0.5-3 h and analyzed 1 and 3 d later. NM caused a dose-dependent increase in cytotoxicity and a reduction in metabolic activity, as measured by LDH release and WST-1 activity, respectively. Optimal responses were observed with 50 μM NM after 1 h incubation and these conditions were used in further experiments. Analysis of PCLS bioenergetics using an Agilent Seahorse showed that NM impaired both glycolytic activity and mitochondrial respiration. This was associated with injury to the bronchial epithelium and a reduction in methacholine-induced airway contraction. NM was also found to cause DNA damage in bronchial epithelial cells in PCLS, as measured by expression of γ-H2AX, and to induce oxidative stress, which was evident by a reduction in glutathione levels and upregulation of the antioxidant enzyme catalase. Cleaved caspase-3 was also upregulated in airway smooth muscle cells indicating apoptotic cell death. Characterizing early events in NM toxicity is key in identifying therapeutic targets for the development of efficacious countermeasures.

Animal models of acute exacerbation of pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive scarring interstitial lung disease with an unknown cause. Some patients may experience acute exacerbations (AE), which result in severe lung damage visible on imaging or through examination of tissue samples, often leading to high mortality rates. However, the etiology and pathogenesis of AE-IPF remain unclear. AE-IPF patients exhibit diffuse lung damage, apoptosis of type II alveolar epithelial cells, and an excessive inflammatory response. Establishing a reliable animal model of AE is critical for investigating the pathogenesis. Recent studies have reported a variety of animal models for AE-IPF, each with its own advantages and disadvantages. These models are usually established in mice with bleomycin-induced pulmonary fibrosis, using viruses, bacteria, small peptides, or specific drugs. In this review, we present an overview of different AE models, hoping to provide a useful resource for exploring the mechanisms and targeted therapies for AE-IPF.

Overview of herbal therapy of acute and chronic pulmonary disease: a conceptual map

Purpose

Acute and chronic obstructive pulmonary disease (COPD) is a common and progressive lung disease that makes breathing difficult over time and can even lead to death. Despite this, there is no definitive treatment for it yet. This study aims to evaluate the studies on single and combined herbal interventions affecting COPD.

Design/methodology/approach

In this study, all articles published in English up to 2020 were extracted from the Web of Science (WoS) database and collected using Boolean tools based on keywords, titles and abstracts. Finally, the data required for bibliographic analysis, such as the author(s), publication year, academic journal, institution, country of origin, institution, financial institution and keywords were extracted from the database.

Findings

A total of 573 articles were analyzed. The number of papers in the lung disease field showed an upward trend from 1984 to 2021, and there was a surge in paper publications in 2013. China, Korea and Brazil published the highest number of studies on COPD, and Chinese medical universities published the most papers. Three journals that received the highest scores in this study were the Journal of Ethnopharmacology, International Immunopharmacology and Plos One. In the cloud map, expression, activation and expression were the most frequently researched subjects. In the plus and author keywords, acute lung injury was the most commonly used word. Inflammation, expression of various genes, nitric oxide-dependent pathways, NFkappa B, TNFalpha and lipopolysaccharide-dependent pathways were the mechanisms underlying COPD. Scientometric analysis of COPD provides a vision for future research and policymaking.

Originality/value

This study aimed to evaluate the studies on single and combined herbal interventions affecting COPD.

Impaired energy metabolism and altered functional activity of alveolar type II epithelial cells following exposure of rats to nitrogen mustard

Nitrogen mustard (NM) is a cytotoxic vesicant known to cause acute lung injury which progresses to fibrosis. Alveolar Type II cells are primarily responsible for surfactant production; they also play a key role in lung repair following injury. Herein, we assessed the effects of NM on Type II cell activity. Male Wistar rats were administered NM (0.125 mg/kg) or PBS control intratracheally. Type II cells, lung tissue and BAL were collected 3 d later. NM exposure resulted in double strand DNA breaks in Type II cells, as assessed by expression of γH2AX; this was associated with decreased expression of the DNA repair protein, PARP1. Expression of HO-1 was upregulated and nitrotyrosine residues were noted in Type II cells after NM exposure indicating oxidative stress. NM also caused alterations in Type II cell energy metabolism; thus, both glycolysis and oxidative phosphorylation were reduced; there was also a shift from a reliance on oxidative phosphorylation to glycolysis for ATP production. This was associated with increased expression of pro-apoptotic proteins activated caspase-3 and -9, and decreases in survival proteins, β-catenin, Nur77, HMGB1 and SOCS2. Intracellular signaling molecules important in Type II cell activity including PI3K, Akt2, phospho-p38 MAPK and phospho-ERK were reduced after NM exposure. This was correlated with dysregulation of surfactant protein production and impaired pulmonary functioning. These data demonstrate that Type II cells are targets of NM-induced DNA damage and oxidative stress. Impaired functioning of these cells may contribute to pulmonary toxicity caused by mustards.

A review of chemical warfare agents linked to respiratory and neurological effects experienced in Gulf War Illness

Over 40% of veterans from the Persian Gulf War (GW) (1990-1991) suffer from Gulf War Illness (GWI). Thirty years since the GW, the exposure and mechanism contributing to GWI remain unclear. One possible exposure that has been attributed to GWI are chemical warfare agents (CWAs). While there are treatments for isolated symptoms of GWI, the number of respiratory and cognitive/neurological issues continues to rise with minimum treatment options. This issue does not only affect veterans of the GW, importantly these chronic multisymptom illnesses (CMIs) are also growing amongst veterans who have served in the Afghanistan-Iraq war. What both wars have in common are their regions and inhaled exposures. In this review, we will describe the CWA exposures, such as sarin, cyclosarin, and mustard gas in both wars and discuss the various respiratory and neurocognitive issues experienced by veterans. We will bridge the respiratory and neurological symptoms experienced to the various potential mechanisms described for each CWA provided with the most up-to-date models and hypotheses.

Optimizing antidotal treatment with the oral HSP90 inhibitor TAS-116 against hydrochloric acid-induced pulmonary fibrosis in mice

Exposure to high concentrations of hydrochloric acid (HCl) can lead to severe acute and chronic lung injury. In the aftermath of accidental spills, victims may be treated for the acute symptoms, but the chronic injury is often overlooked. We have developed a mouse model of acute and chronic lung injury, in which the peak of acute lung injury occurs on the day 4 after HCl exposure. We have also demonstrated that HSP90 inhibitors are effective antidotes when administered starting 24 h after HCl. In this study we examined the hypothesis that the novel oral HSP90 inhibitor TAS-116 can effectively ameliorate HCl-induced lung injury even when treatment starts at the peak of the acute injury, as late as 96 h after HCl. C57BI/6J mice were intratracheally instilled with 0.1N HCl. After 24 or 96 h, TAS-116 treatment began (3.5, 7 or 14 mg/kg, 5 times per week, p. o.) for either 2,3 or 4 or weeks. TAS-116 moderated the HCl-induced alveolar inflammation, as reflected in the reduction of white blood cells and total protein content in bronchoalveolar lavage fluid (BALF), overexpression of NLRP3 inflammasome, and inhibited the activation of pro-fibrotic pathways. Furthermore, TAS-116 normalized lung mechanics and decreased the deposition of extracellular matrix proteins in the lungs of mice exposed to HCl. Delayed and shortened treatment with TAS-116, successfully blocked the adverse chronic effects associated with acute exposure to HCl.

Alcohol Increases Lung Angiotensin-Converting Enzyme 2 Expression and Exacerbates Severe Acute Respiratory Syndrome Coronavirus 2 Spike Protein Subunit 1-Induced Acute Lung Injury in K18-hACE2 Transgenic Mice

During the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, alcohol consumption increased markedly. Nearly one in four adults reported drinking more alcohol to cope with stress. Chronic alcohol abuse is now recognized as a factor complicating the course of acute respiratory distress syndrome and increasing mortality. To investigate the mechanisms behind this interaction, a combined acute respiratory distress syndrome and chronic alcohol abuse mouse model was developed by intratracheally instilling the subunit 1 (S1) of SARS-CoV-2 spike protein (S1SP) in K18-human angiotensin-converting enzyme 2 (ACE2) transgenic mice that express the human ACE2 receptor for SARS-CoV-2 and were kept on an ethanol diet. Seventy-two hours after S1SP instillation, mice on an ethanol diet showed a strong decrease in body weight, a dramatic increase in white blood cell content of bronchoalveolar lavage fluid, and an augmented cytokine storm, compared with S1SP-treated mice on a control diet. Histologic examination of lung tissue showed abnormal recruitment of immune cells in the alveolar space, abnormal parenchymal architecture, and worsening Ashcroft score in S1SP- and alcohol-treated animals. Along with the activation of proinflammatory biomarkers [NF-κB, STAT3, NLR family pyrin domain-containing protein 3 (NLRP3) inflammasome], lung tissue homogenates from mice on an alcohol diet showed overexpression of ACE2 compared with mice on a control diet. This model could be useful for the development of therapeutic approaches against alcohol-exacerbated coronavirus disease 2019.

Toxicological effects of traffic-related air pollution on the lungs: Evidence, biomarkers and intervention

BACKGROUND

Numerous epidemiological studies have recently observed that exposure to traffic-related air pollution (TRAP) is associated with increased risk of various respiratory diseases. Major gaps in knowledge remain regarding the toxicological effects.

OBJECTIVES

We examined the toxicological effects of the gasoline exhaust particles (GEP), a paradigm of TRAP, in rats, with an objective to provide the evidence, obtain the biomarkers, and suggest effective intervention measure.

METHODS

We measured the airway hyperresponsiveness (AHR), inflammatory cells in the bronchoalveolar lavage (BAL) fluid, histological changes in the lung tissues, and the biomarkers so as to systematically examine the toxicological effects of GEPs at different dose levels (0.5, 2.5, 5 mg/kg BW). The intervention of vitamin E (VE), a natural antioxidant, on the toxicological effects was investigated.

RESULTS

The lung injury caused by GEP exposure was first indicated by the airway hyperresponsiveness (AHR). Compared with the control group, GEP exposure significantly increased the airway resistances and decreased the lung compliance; the higher the dose of GEP, the more serious the lung injury. Lung injury was also revealed by the increase of inflammatory cells, including the lymphocytes and neutrophils, in the BAL fluid. With the increase of GEP dose, histological changes in the lung tissues were further observed: inflammatory cell infiltration increased and alveolar wall thickened. The toxicology of GEP was demonstrated by the increase of the biomarkers of the oxidative stress, the pro-inflammatory cytokines and the apoptosis cytokine. However, administration of VE was found to be effective in restoring airway injury.

CONCLUSION

The toxicological effects of traffic-related air pollution (TRAP) on rat lungs are supported by evidence and biomarkers, and vitamin E intervention is feasible.

The Heat Shock Protein 90 Inhibitor, AT13387, Protects the Alveolo-Capillary Barrier and Prevents HCl-Induced Chronic Lung Injury and Pulmonary Fibrosis

Hydrochloric acid (HCl) exposure causes asthma-like conditions, reactive airways dysfunction syndrome, and pulmonary fibrosis. Heat Shock Protein 90 (HSP90) is a molecular chaperone that regulates multiple cellular processes. HSP90 inhibitors are undergoing clinical trials for cancer and are also being studied in various pre-clinical settings for their anti-inflammatory and anti-fibrotic effects. Here we investigated the ability of the heat shock protein 90 (HSP90) inhibitor AT13387 to prevent chronic lung injury induced by exposure to HCl in vivo and its protective role in the endothelial barrier in vitro. We instilled C57Bl/6J mice with 0.1N HCl (2 µL/g body weight, intratracheally) and after 24 h began treatment with vehicle or AT13387 (10 or 15 mg/kg, SC), administered 3×/week; we analyzed histological, functional, and molecular markers 30 days after HCl. In addition, we monitored transendothelial electrical resistance (TER) and protein expression in a monolayer of human lung microvascular endothelial cells (HLMVEC) exposed to HCl (0.02 N) and treated with vehicle or AT13387 (2 µM). HCl provoked persistent alveolar inflammation; activation of profibrotic pathways (MAPK/ERK, HSP90); increased deposition of collagen, fibronectin and elastin; histological evidence of fibrosis; and a decline in lung function reflected in a downward shift in pressure-volume curves, increased respiratory system resistance (Rrs), elastance (Ers), tissue damping (G), and hyperresponsiveness to methacholine. Treatment with 15 mg/kg AT13387reduced alveolar inflammation, fibrosis, and NLRP3 staining; blocked activation of ERK and HSP90; and attenuated the deposition of collagen and the development of chronic lung injury and airway hyperreactivity. In vitro, AT13387 prevented HCl-induced loss of barrier function and AKT, ERK, and ROCK1 activation, and restored HSP70 and cofilin expression. The HSP90 inhibitor, AT13387, represents a promising drug candidate for chronic lung injury that can be administered subcutaneously in the field, and at low, non-toxic doses.

Dietary Phytoestrogens Ameliorate Hydrochloric Acid-Induced Chronic Lung Injury and Pulmonary Fibrosis in Mice

We previously reported that female mice exhibit protection against chemically induced pulmonary fibrosis and suggested a potential role of estrogen. Phytoestrogens act, at least in part, via stimulation of estrogen receptors; furthermore, compared to residents of Western countries, residents of East Asian countries consume higher amounts of phytoestrogens and exhibit lower rates of pulmonary fibrosis. Therefore, we tested the hypothesis that dietary phytoestrogens ameliorate the severity of experimentally induced pulmonary fibrosis. Male mice placed on either regular soybean diet or phytoestrogen-free diet were instilled with 0.1 N HCl to provoke pulmonary fibrosis. Thirty days later, lung mechanics were measured as indices of lung function and bronchoalveolar lavage fluid (BALF) and lung tissue were analyzed for biomarkers of fibrosis. Mice on phytoestrogen-free diet demonstrated increased mortality and stronger signs of chronic lung injury and pulmonary fibrosis, as reflected in the expression of collagen, extracellular matrix deposition, histology, and lung mechanics, compared to mice on regular diet. We conclude that dietary phytoestrogens play an important role in the pathogenesis of pulmonary fibrosis and suggest that phytoestrogens (e.g., genistein) may be useful as part of a therapeutic regimen against hydrochloric acid-induced lung fibrosis and chronic lung dysfunction.

Age-Dependent Chronic Lung Injury and Pulmonary Fibrosis following Single Exposure to Hydrochloric Acid

Exposure to hydrochloric acid (HCl) represents a threat to public health. Children may inhale higher doses and develop greater injury because of their smaller airways and faster respiratory rate. We have developed a mouse model of pediatric exposure to HCl by intratracheally instilling p24 mice (mice 24 days old; 8-10 g) with 2 µL/g 0.1 N HCl, and compared the profile of lung injury to that in HCl-instilled adults (10 weeks old; 25-30 g) and their age-matched saline controls. After 30 days, alveolar inflammation was observed with increased proteinosis and mononuclear cells in the bronchoalveolar lavage fluid (BALF) in both HCl-instilled groups. Young p24 animals-but not adults-exhibited higher NLR family pyrin domain containing 3 (NLRP3) inflammasome levels. Increased amounts of Transforming Growth Factor-β (TGF-β) mRNA and its intracellular canonical and non-canonical pathways (p-Smad2 and p-ERK) were found in the lungs of both young and adult HCl-instilled mice. Constitutive age-related differences were observed in the levels of heat shock protein family (HSP70 and HSP90). HCl equally provoked the deposition of collagen and fibronectin; however, significant age-dependent differences were observed in the increase in elastin and tenascin C mRNA. HCl induced pulmonary fibrosis with an increased Ashcroft score, which was higher in adults, and a reduction in alveolar Mean Alveolar Linear Intercept (MALI). Young mice developed increased Newtonian resistance (Rn) and lower PV loops, while adults showed a higher respiratory system resistance and elastance. This data indicate that young p24 mice can suffer long-term complications from a single exposure to HCl, and can develop chronic lung injury characterized by a stronger persistent inflammation and lesser fibrotic pattern, mostly in the airways, differently from adults. Further data are required to characterize HCl time- and dose-dependent injury in young animals and to identify new key-molecular targets.

Sex-Related Differences in Murine Models of Chemically Induced Pulmonary Fibrosis

We developed two models of chemically induced chronic lung injury and pulmonary fibrosis in mice (intratracheally administered hydrochloric acid (HCl) and intratracheally administered nitrogen mustard (NM)) and investigated male–female differences. Female mice exhibited higher 30-day survival and less weight loss than male mice. Thirty days after the instillation of either HCl or NM, bronchoalveolar lavage fluid displayed a persistent, mild inflammatory response, but with higher white blood cell numbers and total protein content in males vs. females. Furthermore, females exhibited less collagen deposition, milder pulmonary fibrosis, and lower Ashcroft scores. After instillation of either HCl or NM, all animals displayed increased values of phosphorylated (activated) Heat Shock Protein 90, which plays a crucial role in the alveolar wound-healing processes; however, females presented lower activation of both transforming growth factor-β (TGF-β) signaling pathways: ERK and SMAD. We propose that female mice are protected from chronic complications of a single exposure to either HCl or NM through a lesser activation of TGF-β and downstream signaling. The understanding of the molecular mechanisms that confer a protective effect in females could help develop new, gender-specific therapeutics for IPF.

Nutraceuticals as potential therapeutics for vesicant-induced pulmonary fibrosis

Exposure to vesicants, including sulfur mustard and nitrogen mustard, causes damage to the epithelia of the respiratory tract and the lung. With time, this progresses to chronic disease, most notably, pulmonary fibrosis. The pathogenic process involves persistent inflammation and the release of cytotoxic oxidants, cytokines, chemokines, and profibrotic growth factors, which leads to the collapse of lung architecture, with fibrotic involution of the lung parenchyma. At present, there are no effective treatments available to combat this pathological process. Recently, much interest has focused on nutraceuticals, substances derived from plants, herbs, and fruits, that exert pleiotropic effects on inflammatory cells and parenchymal cells that may be useful in reducing fibrogenesis. Some promising results have been obtained with nutraceuticals in experimental animal models of inflammation-driven fibrosis. This review summarizes the current knowledge on the putative preventive/therapeutic efficacy of nutraceuticals in progressive pulmonary fibrosis, with a focus on their activity against inflammatory reactions and profibrotic cell differentiation.

HSP90 Inhibition and Modulation of the Proteome: Therapeutical Implications for Idiopathic Pulmonary Fibrosis (IPF)

Idiopathic Pulmonary fibrosis (IPF) is a catastrophic disease with poor outcomes and limited pharmacological approaches. Heat shock protein 90 (HSP90) has been recently involved in the wound-healing pathological response that leads to collagen deposition in patients with IPF and its inhibition represents an exciting drug target against the development of pulmonary fibrosis. Under physiological conditions, HSP90 guarantees proteostasis through the refolding of damaged proteins and the degradation of irreversibly damaged ones. Additionally, its inhibition, by specific HSP90 inhibitors (e.g., 17 AAG, 17 DAG, and AUY-922) has proven beneficial in different preclinical models of human disease. HSP90 inhibition modulates a complex subset of kinases and interferes with intracellular signaling pathways and proteome regulation. In this review, we evaluated the current evidence and rationale for the use of HSP90 inhibitors in the treatment of pulmonary fibrosis, discussed the intracellular pathways involved, described the limitations of the current understanding and provided insights for future research.

The HSP90 Inhibitor, AUY-922, Ameliorates the Development of Nitrogen Mustard-Induced Pulmonary Fibrosis and Lung Dysfunction in Mice

Increased levels of heat shock protein 90 (HSP90) have been recently implicated in the pathogenesis of pulmonary fibrosis and the use of HSP90 inhibitors constitutes a potential therapeutic approach. Similarly, acute exposure to nitrogen mustard (NM) is related to the development of chronic lung injury driven by TNF-α, TGF-β, ERK and HSP90. Thus, we developed a murine model of NM-induced pulmonary fibrosis by instilling C57BI/6J mice with 0.625 mg/kg mechlorethamine hydrochloride. After 24 h, mice began receiving AUY-922, a second generation HSP90 inhibitor, at 1 mg/kg 2 times per week or 2 mg/kg 3 times per week, for either 10 or 30 days. AUY-922 suppressed the NM-induced sustained inflammation, as reflected in the reduction of leukocyte and protein concentrations in bronchoalveolar lavage fluid (BALF), and inhibited the activation of pro-fibrotic biomarkers, ERK and HSP90. Furthermore, AUY-922 maintained normal lung function, decreased the overexpression and accumulation of extracellular matrix proteins, and dramatically reduced histologic evidence of fibrosis in the lungs of mice exposed to NM. The HSP90 inhibitor, AUY-922, successfully blocked the adverse effects associated with acute exposures to NM, representing a promising approach against NM-induced pulmonary fibrosis.