Influence of glutathione-S-transferase (GST) inhibition on lung epithelial cell injury: role of oxidative stress and metabolism

Heterogeneous Oxidation Products of Fine Particulate Isoprene Epoxydiol-Derived Methyltetrol Sulfates Increase Oxidative Stress and Inflammatory Gene Responses in Human Lung Cells

Hydroxyl radical (·OH)-initiated oxidation of isoprene, the most abundant nonmethane hydrocarbon in the atmosphere, is responsible for substantial amounts of secondary organic aerosol (SOA) within ambient fine particles. Fine particulate 2-methyltetrol sulfate diastereoisomers (2-MTSs) are abundant SOA products formed via acid-catalyzed multiphase chemistry of isoprene-derived epoxydiols with inorganic sulfate aerosols under low-nitric oxide conditions. We recently demonstrated that heterogeneous ·OH oxidation of particulate 2-MTSs leads to the particle-phase formation of multifunctional organosulfates (OSs). However, it remains uncertain if atmospheric chemical aging of particulate 2-MTSs induces toxic effects within human lung cells. We show that inhibitory concentration-50 (IC50) values decreased from exposure to fine particulate 2-MTSs that were heterogeneously aged for 0 to 22 days by ·OH, indicating increased particulate toxicity in BEAS-2B lung cells. Lung cells further exhibited concentration-dependent modulation of oxidative stress- and inflammatory-related gene expression. Principal component analysis was carried out on the chemical mixtures and revealed positive correlations between exposure to aged multifunctional OSs and altered expression of targeted genes. Exposure to particulate 2-MTSs alone was associated with an altered expression of antireactive oxygen species (ROS)-related genes (NQO-1, SOD-2, and CAT) indicative of a response to ROS in the cells. Increased aging of particulate 2-MTSs by ·OH exposure was associated with an increased expression of glutathione pathway-related genes (GCLM and GCLC) and an anti-inflammatory gene (IL-10).

The Role of Phospholipase Activity of Peroxiredoxin 6 in Its Transmembrane Transport and Protective Properties

Peroxiredoxin 6 (Prdx6) is a multifunctional eukaryotic antioxidant enzyme. Mammalian Prdx6 possesses peroxidase activity against a wide range of organic and inorganic hydroperoxides, as well as exhibits phospholipase A2 (aiPLA2) activity, which plays an important role in the reduction of oxidized phospholipids and cell membrane remodeling. Exogenous Prdx6 has recently been shown to be able to penetrate inside the cell. We hypothesized that this entry may be due to the phospholipase activity of Prdx6. Experiments using exogenous Prdx6 in three cell lines (3T3, A549, RAW 264.7) demonstrated that it is the phospholipase activity that promotes its penetration into the cell. Overoxidation of Prdx6 led to a suppression of the peroxidase activity and a 3-to-4-fold growth of aiPLA2, which enhanced the efficiency of its transmembrane transport into the cells by up to 15 times. A mutant form of Prdx6-S32A with an inactivated phospholipase center turned out to be unable to enter the cells in both the reduced and oxidized state of the peroxidase active center. Previously, we have shown that exogenous Prdx6 has a significant radioprotective action. However, the role of phospholipase activity in the radioprotective effects of Prdx6 remained unstudied. Trials with the mutant Prdx6-S32A form, with the use of a total irradiation model in mice, showed a nearly 50% reduction of the radioprotective effect upon aiPLA2 loss. Such a significant decrease in the radioprotective action may be due to the inability of Prdx6-S32A to penetrate animal cells, which prevents its reduction by the natural intracellular reducing agent glutathione S-transferase (πGST) and lowers the efficiency of elimination of peroxides formed from the effect of ionizing radiation. Thus, phospholipase activity may play an important role in the reduction of oxidized Prdx6 and manifestation of its antioxidant properties.

Role of Sirtuins in Physiology and Diseases of the Central Nervous System

Silent information regulators, sirtuins (SIRTs), are a family of enzymes which take part in major posttranslational modifications of proteins and contribute to multiple cellular processes, including metabolic and energetic transformations, as well as regulation of the cell cycle. Recently, SIRTs have gained increased attention as the object of research because of their multidirectional activity and possible role in the complex pathomechanisms underlying human diseases. The aim of this study was to review a current literature evidence of SIRTs' role in the physiology and pathology of the central nervous system (CNS). SIRTs have been demonstrated to be crucial players in the crosstalk between neuroinflammation, neurodegeneration, and metabolic alterations. The elucidation of SIRTs' role in the background of various CNS diseases offers a chance to define relevant markers of their progression and promising candidates for novel therapeutic targets. Possible diagnostic and therapeutic implications from SIRTs-related investigations are discussed, as well as their future directions and associated challenges.

The Leucocyte Telomere Length, GSTM1 and GSTT1 Null Genotypes and the Risk of Chronic Obstructive Pulmonary Disease

Simple Summary

Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation and oxidative stress, both in the airways and blood, and in other organs. Elevated oxidative stress and inflammation have been reported to affect leucocyte telomere length (LTL). We explored the link between GSTM1 and GSTT1 gene polymorphisms, LTL and COPD risk. For GSTM1 and GSTT1, we genotyped 152 COPD patients and 131 non-affected controls, while for TL, we assessed 91 patients and 88 controls. There was a significant difference in GSTM1 null genotype frequency between the patients and controls (0.59 vs. 0.38, p ≤ 0.000), but such was not found for GSTT1 (p = 0.192). COPD patients carrying the GSTM1 null genotype had shorter telomeres compared to those carrying the non-null genotype (15,720 bp vs. 22,442 bp, p = 0.008); and in controls, the opposite occurred (31,354 bp vs. 17,800 bp, p = 0.020). According to our results GSTM1, but not GSTT1, null genotypes might play role in leucocyte telomere shortening, and thus be involved in the pathogenesis of COPD.

Abstract

Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation and oxidative stress both in the airways and blood and other organs. Elevated oxidative stress and inflammation have been reported to affect leucocyte telomere length (LTL). Glutathione S-transferase (GST) enzymes are a large family of xenobiotic-metabolizing enzymes that utilize different ROS products. We aimed to explore the link between GSTM1 and GSTT1 gene polymorphisms, LTL and COPD risk. For GSTM1, we genotyped 152 COPD patients and 131 non-affected controls; for GSTT1, we genotyped 149 COPD patients and 130 controls. We were able to assess TL for 91 patients and 88 controls. There was a significant difference in the GSTM1 null genotype frequency between the patients and controls (0.59 vs. 0.38, p ≤ 0.000), but such was not found for GSTT1 (p = 0.192). When combining both polymorphisms, we obtained a significantly greater presence of at least one null genotype among patients (0.12 vs. 0.05, p = 0.027). An association between GSTT1 and LTL was not found. COPD patients carrying the GSTM1 null genotype had shorter telomeres compared to those carrying the non-null genotype (15,720 bp vs. 22,442 bp, p = 0.008); as for the controls, it was the opposite (31,354 bp vs. 17,800 bp, p = 0.020). The significance in both groups remained when combining GSTM1 and GSTT1 (COPD (at least one null) 16,409 bp vs. COPD (non-null) 22,092 bp, p = 0.029; control (at least one null) 29,666 bp vs. control (non-null) 16,370 bp, p = 0.027). The total glutathione level in GSTM1 non-null controls was higher compared to the null genotype (15.39 ng/mL vs. 5.53 ng/mL, p = 0.002). In COPD patients, we found no association (p = 0.301). In conclusion, according to our results, GSTM1, but not GSTT1, null genotypes might play a role in leucocyte telomere shortening, and thus be involved in the pathogenesis of COPD.

GSTP1 as a novel target in radiation induced lung injury

The glutathione S-transferase P1(GSTP1) is an isoenzyme in the glutathione-S transferases (GSTs) enzyme system, which is the most abundant GSTs expressed in adult lungs. Recent research shows that GSTP1 is closely related to the regulation of cell oxidative stress, inhibition of cell apoptosis and promotion of cytotoxic metabolism. Interestingly, there is evidence that GSTP1 single nucleotide polymorphisms (SNP) 105Ile/Val related to the risk of radiation induced lung injury (RILI) development, which strongly suggests that GSTP1 is closely associated with the occurrence and development of RILI. In this review, we discuss our understanding of the role of GSTP1 in RILI and its possible mechanism.

Identification of proteins and cellular pathways targeted by 2-nitroimidazole hypoxic cytotoxins

Tumour hypoxia negatively impacts therapy outcomes and continues to be a major unsolved clinical problem. Nitroimidazoles are hypoxia selective compounds that become entrapped in hypoxic cells by forming drug-protein adducts. They are widely used as hypoxia diagnostics and have also shown promise as hypoxia-directed therapeutics. However, little is known about the protein targets of nitroimidazoles and the resulting effects of their modification on cancer cells. Here, we report the synthesis and applications of azidoazomycin arabinofuranoside (N3-AZA), a novel click-chemistry compatible 2-nitroimidazole, designed to facilitate (a) the LC-MS/MS-based proteomic analysis of 2-nitroimidazole targeted proteins in FaDu head and neck cancer cells, and (b) rapid and efficient labelling of hypoxic cells and tissues. Bioinformatic analysis revealed that many of the 62 target proteins we identified participate in key canonical pathways including glycolysis and HIF1A signaling that play critical roles in the cellular response to hypoxia. Critical cellular proteins such as the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and the detoxification enzyme glutathione S-transferase P (GSTP1) appeared as top hits, and N3-AZA adduct formation significantly reduced their enzymatic activities only under hypoxia. Therefore, GAPDH, GSTP1 and other proteins reported here may represent candidate targets to further enhance the potential for nitroimidazole-based cancer therapeutics.

Evaluation of the hepatoprotective effects of curcumin and nanocurcumin against paraquat-induced liver injury in rats: Modulation of oxidative stress and Nrf2 pathway

Paraquat (PQ) is a widely used herbicide all over the world, which is highly toxic for animals and humans. Its cytotoxicity is based on reactive radical generation. The aim of this study is to evaluate and compare the hepatoprotective effects of curcumin and nanocurcumin against liver damage caused by sub-acute exposure with PQ via modulation of oxidative stress and genes expression of nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. Rats were exposed to PQ (5 mg/kg/day, orally) + curcumin or nanocurcumin (100 mg/kg/day, orally) for 7 days. Then rats were anesthetized and serum and liver samples were collected. Next, serum enzymatic activities, liver histopathology, oxidative stress, and expression of genes involved in Nrf2 signaling pathway were assessed by biochemical and enzyme-linked immunosorbent assay methods, hematoxylin and eosin staining, and real-time polymerase chain reaction analysis. PQ significantly increased malondialdehyde, alanine transaminase, aspartate aminotransferase, alkaline phosphatase levels, and Kelch-like ECH-associated protein 1 gene expression and also decreased total antioxidant capacity, total thiol group levels, Glutathione S-transferases, heme oxygenase 1, Nrf2, and NAD(P)H:quinone oxidoreductase 1 genes expression, causing histological damages to liver tissue. These changes were significantly modulated by curcumin and nanocurcumin treatments. Our findings showed that nanocurcumin had better hepatoprotective effect than curcumin in liver damage after PQ exposure most likely through modulation of oxidative stress and genes expression of Nrf2 pathway.

Epigenetic study of global gene methylation in PON1, XRCC1 and GSTs different genotypes in rural and urban pesticide exposed workers

Background Epigenetic represents a study of occurred heritable gene expression changes without changing in the DNA sequence. It includes DNA methylation and miRNA expression that attract increasing attention as potential links between the genetic and environmental determinants of health and disease. Pesticide exposure is associated with adverse health effects and DNA methylation due to oxidative stress induced following its exposure. This study aimed to define the association of genetic polymorphisms of XRCC1, PON1, GSTP1 and GST genes with global genes DNA methylation in urban and rural occupationally pesticides exposed workers. Methods This study included 100 pesticides exposed workers; 50 rural sprayers (RE) and 50 urban researchers (UE). Controls included equal numbers. DNA methylation of global genes was evaluated by pyrosequencing assay. XRCC1, PON1 and GSTP1 genotyping were assessed by PCR-RFLP, and GST M1 and T1 were performed by PCR. Results The results of this study revealed that most genotypes in XRCC1, PON1, GSTP1 and GST genes were associated with LINE-1 hypomethylation among UE group. However, heterozygote genotypes (Gln-Arg and Ile-Val) in XRCC1 and GSTP1 genes, respectively, were associated with LINE-1 hypermethylation among UE compared with other corresponding genotypes. Only GSTT1 polymorphism recorded a significant change in percent methylation of Alu elements among urban and rural groups. Conclusion Urbanization could play an additional risk for epigenetic changes associated with pesticide exposure, and that could be attributed to the quality of life including their dietary habits, working and living in closed areas, and their exposure to extra pollutions emitted from urbanization sources.

A Novel Method to Efficiently Highlight Nonlinearly Expressed Genes

For precision medicine, there is a need to identify genes that accurately distinguish the physiological state or response to a particular therapy, but this can be challenging. Many methods of analyzing differential expression have been established and applied to this problem, such as t-test, edgeR, and DEseq2. A common feature of these methods is their focus on a linear relationship (differential expression) between gene expression and phenotype. However, they may overlook nonlinear relationships due to various factors, such as the degree of disease progression, sex, age, ethnicity, and environmental factors. Maximal information coefficient (MIC) was proposed to capture a wide range of associations of two variables in both linear and nonlinear relationships. However, with MIC it is difficult to highlight genes with nonlinear expression patterns as the genes giving the most strongly supported hits are linearly expressed, especially for noisy data. It is thus important to also efficiently identify nonlinearly expressed genes in order to unravel the molecular basis of disease and to reveal new therapeutic targets. We propose a novel nonlinearity measure called normalized differential correlation (NDC) to efficiently highlight nonlinearly expressed genes in transcriptome datasets. Validation using six real-world cancer datasets revealed that the NDC method could highlight nonlinearly expressed genes that could not be highlighted by t-test, MIC, edgeR, and DEseq2, although MIC could capture nonlinear correlations. The classification accuracy indicated that analysis of these genes could adequately distinguish cancer and paracarcinoma tissue samples. Furthermore, the results of biological interpretation of the identified genes suggested that some of them were involved in key functional pathways associated with cancer progression and metastasis. All of this evidence suggests that these nonlinearly expressed genes may play a central role in regulating cancer progression.

Interaction of Glutathione S-Transferase M1, T1, and P1 Genes With Early Life Tobacco Smoke Exposure on Lung Function in Adolescents

BACKGROUND

Glutathione S-transferase (GST) genes are involved in the management of oxidative stress in the lungs. We aimed to determine whether they modify the associations between early life smoke exposure and adverse lung health outcomes.

METHODS

The Melbourne Atopy Cohort study (a high-risk birth cohort) enrolled 620 children and followed them prospectively from birth. We recorded perinatal tobacco smoke exposure, asthma, and lung function at 12 (59%) and 18 years (66%) and genotyped for GSTM1, GSTT1, and GSTP1 (69%).

RESULTS

GST genotypes were found to interact with tobacco smoke exposure on lung function outcomes (P interaction ≤ .05). Only among children with GSTT1 null genotypes was exposure to mother's, father's, or parental tobacco smoke in early life associated with an increased risk of reductions in prebronchodilator (BD) FEV₁ and FVC at both 12 and 18 years. These associations were not seen in children with GSTT1 present. Similarly, only among children with GSTM1 null genotypes was exposure to father's or parental smoking associated with reductions in pre- and post-BD FEV₁ and FVC at 18 years. Only among children with Ile/Ile genotypes of GSTP1 was exposure to mother's smoking associated with increased risk of reduced FEV₁ at 18 years, but this was not the case among children with Val/Val or Ile/Val genotypes.

CONCLUSIONS

Our study provides evidence of interaction between early tobacco smoke exposure and GST genotypes on lung function. Carriers of GST null mutations and GSTP1 Ile/Ile alleles may be more susceptible when exposed to tobacco smoke in early life. These findings support stronger recommendations to protect all infants from tobacco smoke exposure.

TRIAL REGISTRY

Australian and New Zealand Clinical Trials Registry; No.: ACTRN12609000734268; URL: http://www.anzctr.org.au/.

Drug-delivering-drug approach-based codelivery of paclitaxel and disulfiram for treating multidrug-resistant cancer

Multidrug resistance (MDR) is a common intractable barrier in success of clinical cancer chemotherapy. Codelivery of two drugs using nanocarriers is a commonly used approach to treat the MDR cancer. However, the drug payload in the conventional nanocarriers is low and thus compromises the treatment outcomes. Disulfiram (DSF) is promising to reverse MDR and increases the sensitivity of cancer cells to chemotherapy. While, paclitaxel (PTX) is one of the frequently used anticancer drug. Here, by using a drug-delivering-drug (DDD) strategy based on nanocrystals, hybrid PTX-DSF nanocrystals (PTX-DSF Ns) were developed for codelivery of PTX and DSF to reverse MDR in cancer. The 160-nm PTX-DSF Ns with rod-like morphology had drug-loading up to 43% at mass ratio of 5:1. Interestingly, the nanoparticles entered cells via caveolar endocytosis. By reducing intracellular ATP level and GST activity, PTX-DSF Ns killed the Taxol resistant A549 cells with higher efficiency than PTX alone, exhibiting as 6-fold increase of apoptosis in MDR tumor. The nanoparticles circulated in blood over time, accumulated in tumor efficiently and reduced the tumor volume by 12-fold in MDR tumor-bearing BALB/c nude mice and allowed 12-fold apoptosis in tumor. Additionally, the immunohistochemical examination demonstrated the safety of the nanoparticles. Overall, the DDD strategy-based PTX-DSF Ns have promising potential for the treatment of MDR cancer.

Association of glutathione S-transferase theta 1 and glutathione S-transferase mu 1 gene polymorphism with the risk of pre-eclampsia during pregnancy in Bangladesh

AIM

In this study, we analyzed the risk of developing pre-eclampsia with respect to glutathione S-transferase theta 1 (GSTT1) and glutathione S-transferase mu 1 (GSTM1) genotypes. We also tried to find relationship between genotypes and biochemical parameter change in pre-eclampsia patients.

METHODS

In total, 104 pre-eclampsia patients and 200 healthy controls were recruited for the study. Peripheral venous blood was drawn from study subjects and DNA was extracted from whole blood and multiplex polymerase chain reaction method was used to identify genotypes of GSTT1 and GSTM1 gene. All biochemical parameters were measured using colorimetric method.

RESULTS

Serum glutamic pyruvic transaminase level was significantly higher (P < 0.01) and hemoglobin level was significantly lower (P < 0.001) in pre-eclampsia patients compared to control subjects. Significant association was found in GSTM1 null genotype with pre-eclampsia (P < 0.001) with an odds ratio (OR) analysis showing more than four-fold increased risk (OR = 4.75; 95% CI = 2.17-10.39; P <0.001). But for GSTT1 gene, null genotype was not associated with increased risk of developing pre-eclampsia (P > 0.05). In case of GSTT1 and GSTM1, the patients having both null genotypes for GSTT1 and GSTM1 showed significant (P < 0.001) higher risk of developing pre-eclampsia (OR = 7.64; 95% CI = 2.38-24.60; P < 0.001).

CONCLUSION

GSTM1 null genotype increases the risk of pre-eclampsia. Combined GSTT1 and GSTM1 null genotype, the risk was even higher.

In Vitro Modulation of Redox and Metabolism Interplay at the Brain Vascular Endothelium: Genomic and Proteomic Profiles of Sulforaphane Activity

Sulforaphane (SFN) has been shown to protect the brain vascular system and effectively reduce ischemic injuries and cognitive deficits. Given the robust cerebrovascular protection afforded by SFN, the objective of this study was to profile these effects in vitro using primary mouse brain microvascular endothelial cells and focusing on cellular redox, metabolism and detoxification functions. We used a mouse MitoChip array developed and validated at the FDA National Center for Toxicological Research (NCTR) to profile a host of genes encoded by nuclear and mt-DNA following SFN treatment (0-5 µM). Corresponding protein expression levels were assessed (ad hoc) by qRT-PCR, immunoblots and immunocytochemistry (ICC). Gene ontology clustering revealed that SFN treatment (24 h) significantly up-regulated ~50 key genes (>1.5 fold, adjusted p < 0.0001) and repressed 20 genes (<0.7 fold, adjusted p < 0.0001) belonging to oxidative stress, phase 1 & 2 drug metabolism enzymes (glutathione system), iron transporters, glycolysis, oxidative phosphorylation (OXPHOS), amino acid metabolism, lipid metabolism and mitochondrial biogenesis. Our results show that SFN stimulated the production of ATP by promoting the expression and activity of glucose transporter-1, and glycolysis. In addition, SFN upregulated anti-oxidative stress responses, redox signaling and phase 2 drug metabolism/detoxification functions, thus elucidating further the previously observed neurovascular protective effects of this compound.

Conventional and electronic cigarettes dysregulate the expression of iron transporters and detoxifying enzymes at the brain vascular endothelium: In vivo evidence of a gender-specific cellular response to chronic cigarette smoke exposure

It is well established that tobacco smoking is associated with vascular endothelial dysfunction in a causative and dose dependent manner primarily related to the tobacco smoke (TS) content of reactive oxygen species (ROS), nicotine, and oxidative stress (OS) -driven inflammation. Preclinical studies have also shown that nicotine (the principal e-liquid's ingredient used in e-cigarettes (e-Cigs) can also cause OS, exacerbation of cerebral ischemia and secondary brain injury. Likewise, chronic e-Cig vaping could be prodromal to vascular endothelial dysfunctions. Herein, we provide direct evidence that similarly to TS, e-Cig promotes mitochondrial depolarization in primary brain vascular endothelial cells as well as the vascular endothelial cell line bEnd3. In addition, both TS and e-Cig exposure upregulated the transmembrane iron exporter Slc40a1 (crucial to maintain cellular iron and redox homeostasis) and that of porphyrin importer Abcb6 (linked to accelerated atherosclerosis). We then investigated in vivo whether gender plays a role in how chronic TS affect vascular endothelial functions. Our results clearly show chronic TS exposure differentially impacts the expression levels of Phase-II enzymes as well as the iron transporters previously investigated in vitro. Although the physiological implications of the gender-specific differential responses to TS are not fully clear, they do demonstrate that gender is a risk factor that needs to be investigated when assessing the potential impact of chronic smoking and perhaps e-Cig vaping.

Ion channels of the lung and their role in disease pathogenesis

Maintenance of normal epithelial ion and water transport in the lungs includes providing a thin layer of surface liquid that coats the conducting airways. This airway surface liquid is critical for normal lung function in a number of ways but, perhaps most importantly, is required for normal mucociliary clearance and bacterial removal. Preservation of the appropriate level of hydration, pH, and viscosity for the airway surface liquid requires the proper regulation and function of a battery of different types of ion channels and transporters. Here we discuss how alterations in ion channel/transporter function often lead to lung pathologies.

Endothelial cell signaling and ventilator-induced lung injury: molecular mechanisms, genomic analyses, and therapeutic targets

Mechanical ventilation is a life-saving intervention in critically ill patients with respiratory failure due to acute respiratory distress syndrome (ARDS). Paradoxically, mechanical ventilation also creates excessive mechanical stress that directly augments lung injury, a syndrome known as ventilator-induced lung injury (VILI). The pathobiology of VILI and ARDS shares many inflammatory features including increases in lung vascular permeability due to loss of endothelial cell barrier integrity resulting in alveolar flooding. While there have been advances in the understanding of certain elements of VILI and ARDS pathobiology, such as defining the importance of lung inflammatory leukocyte infiltration and highly induced cytokine expression, a deep understanding of the initiating and regulatory pathways involved in these inflammatory responses remains poorly understood. Prevailing evidence indicates that loss of endothelial barrier function plays a primary role in the development of VILI and ARDS. Thus this review will focus on the latest knowledge related to 1) the key role of the endothelium in the pathogenesis of VILI; 2) the transcription factors that relay the effects of excessive mechanical stress in the endothelium; 3) the mechanical stress-induced posttranslational modifications that influence key signaling pathways involved in VILI responses in the endothelium; 4) the genetic and epigenetic regulation of key target genes in the endothelium that are involved in VILI responses; and 5) the need for novel therapeutic strategies for VILI that can preserve endothelial barrier function.

Hhip haploinsufficiency sensitizes mice to age-related emphysema

Genetic variants in Hedgehog interacting protein (HHIP) have consistently been associated with the susceptibility to develop chronic obstructive pulmonary disease and pulmonary function levels, including the forced expiratory volume in 1 s (FEV1), in general population samples by genome-wide association studies. However, in vivo evidence connecting Hhip to age-related FEV1 decline and emphysema development is lacking. Herein, using Hhip heterozygous mice (Hhip(+/-)), we observed increased lung compliance and spontaneous emphysema in Hhip(+/-) mice starting at 10 mo of age. This increase was preceded by increases in oxidative stress levels in the lungs of Hhip(+/-) vs. Hhip(+/+) mice. To our knowledge, these results provide the first line of evidence that HHIP is involved in maintaining normal lung function and alveolar structures. Interestingly, antioxidant N-acetyl cysteine treatment in mice starting at age of 5 mo improved lung function and prevented emphysema development in Hhip(+/-) mice, suggesting that N-acetyl cysteine treatment limits the progression of age-related emphysema in Hhip(+/-) mice. Therefore, reduced lung function and age-related spontaneous emphysema development in Hhip(+/-) mice may be caused by increased oxidative stress levels in murine lungs as a result of haploinsufficiency of Hhip.