Deficient DNASE1L3 facilitates neutrophil extracellular traps-induced invasion via cyclic GMP-AMP synthase and the non-canonical NF-κB pathway in diabetic hepatocellular carcinoma.

Objective: Diabetic hepatocellular carcinoma (HCC) patients have high mortality and metastasis rates. Diabetic conditions promote neutrophil extracellular traps (NETs) generation, which mediates HCC metastasis and invasion. However, whether and how diabetes-induced NETs trigger HCC invasion is largely unknown. Here, we aimed to observe the effects of diabetes-induced NETs on HCC invasion and investigate mechanisms relevant to a DNA sensor cyclic GMP-AMP synthase (cGAS). Methods: Serum from diabetic patients and healthy individuals was collected. Human neutrophil-derived NETs were isolated for stimulating HCC cell invasion. Data from the SEER and TCGA databases were used for bioinformatics analysis. In HCC cells and allograft models, NETs-triggered invasion was observed. Results: Diabetic HCC patients had poorer survival than non-diabetic ones. Either diabetic serum or extracted NETs caused HCC invasion. Induction of diabetes or NETosis elicited HCC allograft invasion in nude mice. HCC cell invasion was attenuated by the treatment with DNase1. In TCGA_LIHC, an extracellular DNase DNASE1L3 was downregulated in tumor tissues, while function terms (the endocytic vesicle membrane, the NF-κB pathway and extracellular matrix disassembly) were enriched. DNASE1L3 knockdown in LO2 hepatocytes or H22 cell-derived allografts facilitated HCC invasion in NETotic or diabetic nude mice. Moreover, exposure of HCC cells to NETs upregulated cGAS and the non-canonical NF-κB pathway and induced expression of metastasis genes (MMP9 and SPP1). Both cGAS inhibitor and NF-κB RELB knockdown diminished HCC invasion caused by NETs DNA. Also, cGAS inhibitor was able to retard translocation of NF-κB RELB. Conclusion: Defective DNASE1L3 aggravates NETs DNA-triggered HCC invasion on diabetic conditions via cGAS and the non-canonical NF-κB pathway.

Multiplayer Noncooperative and Cooperative Minimax H∞ Tracking Game Strategies for Linear Mean-Field Stochastic Systems With Applications to Cyber-Social Systems.

The multiplayer stochastic noncooperative tracking game (NTG) with conflicting target strategy and cooperative tracking game (CTG) with a common target strategy of the mean-field stochastic jump-diffusion (MFSJD) system with external disturbance is investigated in this study. Due to the mean (collective) behavior in the system dynamic and cost function, the designs of the NTG strategy and CTG strategy for target tracking of the MFSJD system are more difficult than the conventional stochastic system. By the proposed indirect method, the NTG and CTG strategy design problems are transformed into linear matrix inequalities (LMIs)-constrained multiobjective optimization problem (MOP) and LMIs-constrained single-objective optimization problem (SOP), respectively. The LMIs-constrained MOP could be solved effectively for all Nash equilibrium solutions of NTG at the Pareto front by the proposed LMIs-constrained multiobjective evolutionary algorithm (MOEA). Two simulation examples, including the share market allocation and network security strategies in cyber-social systems, are given to illustrate the design procedure and validate the effectiveness of the proposed LMI-constrained MOEA for all Nash equilibrium solutions of NTG strategies of the MFSJD system.

Data Analysis-Driven Precise Asthmatic Treatment by Targeting Mast Cells.

BACKGROUND: Although the importance of mast cells in asthma has been studied, mast cellsinduced global changes in lungs are largely unknown. Data-driven identification contributes to discovering significant biomarkers or therapeutic targets, which are the basis of effective clinical medications. OBJECTIVE: This study aims to explore the effects of mast cells on gene expression in asthmatic lungs, and to assess the curative effects of inhaled budesonide (BUD). METHODS: Pulmonary gene expression in KitWsh mice with or without mast cell engraftment was analyzed with R software. Functional enrichment of Gene Ontology and KEGG was carried out through the DAVID online tool. Hub genes were identified with String and Cytoscape software. RESULTS: The array analyses showed that the mast cell engraftment enhanced inflammation/immune response, cytokine/chemokine signal, and monocyte/neutrophil/lymphocyte chemotaxis. Interleukin (IL)-6 was identified to be a significant hub gene with the highest interaction degree. Based on this, the effects of BUD were investigated on the aspects of anti-inflammation. BUD's treatment was found to reduce serum IL-6 content and pulmonary inflammation in ovalbumin-induced asthma rats. The treatment also downregulated beta-tryptase expression both in lung tissues and serum. Morphologically, the accumulation and degranulation of mast cells were significantly suppressed. Notably, the effects of BUD on inflammation and degranulation were comparable with Tranilast (a classic mast cell inhibitor), while a remarkable synergy was not observed. CONCLUSION: This study presented a unique pulmonary gene profile induced by mast cell engraftment, which could be reversed through blockage of mast cells or inhaled BUD.

Metabolic Reprogramming of Sulfur in Hepatocellular Carcinoma and Sulfane Sulfur-Triggered Anti-Cancer Strategy.

Metabolic reprogramming is a cancer hallmark. Although the reprogramming of central carbon has been well documented, the role of sulfur metabolism has been largely overlooked. Additionally, the effects of sulfur are sometimes contradictory in tumorigenesis. In this study, we aimed to investigate the gene expression profile in hepatocellular carcinoma (HCC) and the effects of reactive sulfur species (RSS) on HCC tumor cells. Furthermore, the cell imaging technology was applied to discover some potential anti-cancer compounds. Gene Set Enrichment Analysis (GSEA) of Gene Expression Omnibus (GEO) dataset (GSE102083) revealed that sulfur amino acid-related metabolism and vitamin B6 binding activity in HCC tissues were downregulated. Calculation of the interaction network identified nine hub genes, among which eight were validated by differential expression and survival analysis in the TCGA_LIHC cohort, and two (CSE and CBS) had the highest enrichment degree. The metabolomics analysis suggested that the hub genes were associated with RSS metabolism including H2S, H2S2, cystine, cysteine, homocysteine, cystathionine, and methionine. The cell viability assay demonstrated that H2S2 had significant anti-cancer effects in HCC SNU398 tumor cells. The cell imaging assay showed that treatment with H2S2 remarkably increased intracellular sulfane sulfur content. On this basis, the anti-cancer activity of some other sulfane sulfur compounds, such as DATS and DADS, was further verified. Lastly, according to the fact that HCC tumor cells preferentially take in cystine due to high expression of SLC7A11 (a cystine/glutamate transporter), persulfided cysteine precursor (PSCP) was tested for its sulfane sulfur release capability and found to selectively inhibit HCC tumor cell viability. Collectively, this study uncovered sulfur metabolism in HCC was reprogrammed, and provided a potential therapeutic strategy for HCC by donating sulfane sulfur.

How Does Diabetes Impair Penile Tissues during Erectile Dysfunction?

BACKGROUND: Erectile dysfunction (ED) is a significant but underestimated complication during diabetes mellitus (DM). Currently, few special treatments are available clinically due to the lack of specific therapeutic targets. Genomic analysis can be helpful to find potential targets. In this study, the gene expression under diabetic ED condition was analyzed using a gene array, and the significance of the outcomes was evaluated through clinical data. METHODS: The expressions of 15923 genes were analyzed using R software. Differential expression genes (DEGs) were identified through the constructed volcano plot. The function enrichment of Gene Ontology (GO) and KEGG was screened with the DAVID online tool. The interaction between these DEGs was revealed through constructing a protein-protein interaction network and the hub genes were uncovered using the STRING and Cytoscape tool. Lastly, the data of diabetic ED patients were applied to verify the bioinformatics findings. RESULTS: The study showed that 75 genes in the rat penile tissues were upregulated, while 97 genes were downregulated on the diabetic ED condition. These genes were mainly involved in extracellular matrix composition, collagen fibril organization, as well as protein digestion & absorption. Additionally, insulin-related signaling pathways were affected. The clinical analysis indicated that insulin resistance was associated with the diabetic ED severity. Notably, the bioinformatics analysis also suggested that ferroptosis pathway was probably activated under the diabetic ED condition. CONCLUSION: The impaired protein synthesis induced by deficient insulin signaling is an important cause of the diabetic ED. The improvement of protein synthesis through restoring insulin function may be potentially useful for diabetic ED therapy.

Is Hydrogen Sulfide a Concern During Treatment of Lung Adenocarcinoma With Ammonium Tetrathiomolybdate?

Ammonium tetrathiomolybdate (ATTM) has been used in breast cancer therapy for copper chelation, as elevated copper promotes tumor growth. ATTM is also an identified H2S donor and endogenous H2S facilitates VitB12-induced S-adenosylmethionine (SAM) generation, which have been confirmed in m6A methylation and lung cancer development. The m6A modification was recently shown to participate in lung adenocarcinoma (LUAD) progression. These conflicting analyses of ATTM's anticancer vs. H2S's carcinogenesis suggest that H2S should not be ignored during LUAD's treatment with ATTM. This study was aimed to explore ATTM's effects on LUAD cells and mechanisms associated with H2S and m6A. It was found that treatment with ATTM inhibited cell growth at high concentrations, while enhanced cell growth at low concentrations in three LUAD cell lines (A549, HCC827, and PC9). However, another copper chelator triethylenetetramine, without H2S releasing activity, was not found to induce cell growth. Low ATTM concentrations also elevated m6A content in A549 cells. Analysis of differentially expressed genes in TCGA cohort indicated that m6A writer METTL3 and reader YTHDF1 were upregulated while eraser FTO was downregulated in LUAD tissues, consistent with the findings of protein expression in patient tissues. ATTM treatment of A549 cells significantly increased METTL3/14 and YTHDF1 while decreased FTO expression. Furthermore, inhibition of m6A with shMETTL3 RNA significantly attenuated eukaryotic translation initiation factor (eIF) expressions in A549 cells. Correlation analysis indicated that small nuclear ribonucleic protein PRPF6 was positively expressed with YTHDF1 in LUAD tissues. Knockdown of YTHDF1 partially blocked both basal and ATTM-induced PRPF6 expression, as well as A549 cell growth. Lastly, ATTM treatment not only raised intracellular H2S content but also upregulated H2S-producing enzymes. Exogenous H2S application mimicked ATTM's aforementioned effects, but the effects could be weakened by zinc-induced H2S scavenging. Collectively, H2S impedes ATTM-induced anticancer effects through YTHDF1-dependent PRPF6 m6A methylation in lung adenocarcinoma cells.

S-Persulfidation: Chemistry, Chemical Biology, and Significance in Health and Disease.

Significance: S-Persulfidation generates persulfide adducts (RSSH) on both small molecules and proteins. This process is believed to be critical in the regulation of biological functions of reactive sulfur species such as H2S, as well as in signal transduction. S-Persulfidation also plays regulatory roles in human health and diseases. Recent Advances: Some mechanisms underlying the generation of low-molecular-weight persulfides and protein S-persulfidation in living organisms have been uncovered. Some methods for the specific delivery of persulfides and the detection of persulfides in biological systems have been developed. These advances help to pave the road to better understand the functions of S-persulfidation. Critical Issues: Persulfides are highly reactive and unstable. Currently, their identification relies on trapping them by S-alkylation, but this is not always reliable due to rapid sulfur exchange reactions. Therefore, the presence, identity, and fates of persulfides in biological environments are sometimes difficult to track. Future Directions: Further understanding the fundamental chemistry/biochemistry of persulfides and development of more reliable detection methods are needed. S-Persulfidation in specific protein targets is essential in organismal physiological health and human disease states. Besides cardiovascular and neuronal systems, the roles of persulfidation in other systems need to be further explored. Contradictory results of persulfidation in biology, especially in cancer, need to be clarified.

Hydrogen Sulfide Mediated Tandem Reaction of Selenenyl Sulfides and Its Application in Fluorescent Probe Development.

A unique reaction between H2S and a selenenyl sulfide containing benzoate ester template was discovered. This reaction could be specifically triggered by H2S and lead to ester bond cleavage. The reaction was not affected by the presence of thiols such as glutathione and cysteine. With this reaction, a series of fluorescent probes were synthesized and evaluated. The probes exhibited high sensitivity/selectivity for H2S in both buffers and cells.

Rational Design of a Dual-Reactivity-Based Fluorescent Probe for Visualizing Intracellular HSNO.

Thionitrous acid (HSNO), the smallest S-nitrosothiol, is emerging as a potential key intermediate in cellular redox regulation linking two signaling molecules H2 S and NO. However, the chemical biology of HSNO remains poorly understood. A major hurdle is the lack of methods for selective detection of HSNO in biological systems. Herein, we report the rational design, synthesis, and evaluation of the first fluorescent probe TAP-1 for HSNO detection. TAP-1 showed high selectivity and sensitivity to HSNO in aqueous media and cells, providing a useful tool for understanding the functions of HSNO in biology.

Acyl Selenyl Sulfides as the Precursors for Reactive Sulfur Species (Hydrogen Sulfide, Polysulfide, and Selenyl Sulfide).

Persulfides are receiving increased attention due to their links to hydrogen sulfide (H2S) and hydrogen polysulfide (H2Sn). Their close analogues selenyl sulfides (RSeSHs), however, have limited literature precedent, and their reactivity and possible role in biology are largely unknown. Here, we devised an acyl selenyl sulfide template to study RSeSH chemistry. Their stability and reactivity toward amines/thiols were studied. These compounds can produce H2S or H2S2 under different conditions, suggesting that RSeSHs are possible intermediates.

Data-Driven Identification of Hydrogen Sulfide Scavengers.

Hydrogen sulfide (H2 S) is an important signaling molecule whose up- and down-regulation have specific biological consequences. Although significant advances in H2 S up-regulation, by the development of H2 S donors, have been achieved in recent years, precise H2 S down-regulation is still challenging. The lack of potent/specific inhibitors for H2 S-producing enzymes contributes to this problem. We expect the development of H2 S scavengers is an alternative approach to address this problem. Since chemical sensors and scavengers of H2 S share the same criteria, we constructed a H2 S sensor database, which summarizes key parameters of reported sensors. Data-driven analysis led to the selection of 30 potential compounds. Further evaluation of these compounds identified a group of promising scavengers, based on the sulfonyl azide template. The efficiency of these scavengers in in vitro and in vivo experiments was demonstrated.

Three new diterpenoids from Aralia dumetorum.

Three new diterpenoids, dumetoranes A (1) and B (2), melanocane B (3), together with four known ones including melanocane A (4), ent-15S,16-dihydroxypimar-8(14)-en-19-oic acid (5), ent-pimara-8(14),15-diene-19-oic acid (6), and ent-pimara-8(14),15-diene-19-ol (7) were obtained from the ethanol extract of the roots of Aralia dumetorum. Their structure elucidation was achieved by the methods of spectroscopic HRMS, IR, NMR, and by comparison with literature. The cytotoxicities of compounds 1-3 and 5 were assayed by in vitro MTT methods.

Hydrogen sulfide primes diabetic wound to close through inhibition of NETosis.

Diabetes-induced neutrophil NETosis impairs wound healing through neutrophil extracellular traps (NETs). Reactive oxygen species (ROS)-triggered activation of mitogen-activated protein kinase (MAPK) ERK1/2 and p38 is involved in NETosis. Hydrogen sulfide (H2S), an endogenous signaling molecule, accelerates diabetic wound healing (DWH), and inhibits ROS production, ERK1/2 and p38 activation, while its level is decreased in diabetes. However, it remains unknown whether H2S could accelerate DWH through inhibition of NETosis, and whether this inhibitory effect was associated with blockage of ROS-induced ERK1/2 and p38 activation. In order to solve these problems, serum NETs content was measured in diabetic foot patients and healthy individuals. Wound was created in dorsal skin of LepRdb/db and control mice and NETs content in wound tissues was tested. An in vitro NETosis model was induced by phorbol 12-myristate 13-acetate (PMA) in isolated neutrophils. Effects of H2S in form of Na2S on skin wound healing and NETosis were investigated both in vivo and in vitro. It was found that NETs level was highly increased in diabetic foot patients. Comparing with LepRm+/db mice, DWH was delayed in LepRdb/db mice, accompanied with high NETs level. In PMA-induced NETosis model, peptidylarginine deiminase (PAD)-4 and citrullinated histone H3, as well as NETs components dsDNA framework, myeloperoxidase and neutrophil elastase, were significantly increased. PMA-induced neutrophil NETosis and NETs formation were abolished by treatment with H2S. The delayed DWH of diabetic mice was partially restored by intraperitoneal injection of H2S, meanwhile, the highly expressed NETosis and NETs release were also down-regulated. The treatment with H2S not only attenuated ROS production but also abolished MAPK ERK1/2 and p38 activation. Like the effects of H2S, inhibition of MAPK ERK1/2 or p38 could decrease NETs release. These findings suggests that H2S attenuates NETosis and primes diabetic wound to heal through blockage of ROS-mediated MAPK ERK1/2 and p38 activation.

Strategies for the Design of Donors and Precursors of Reactive Sulfur Species.

Reactive sulfur species (RSS) play regulatory roles in biological systems. Many RSS are highly reactive and transient molecules, making their study difficult. RSS donors or precursors, which are used to specifically produce or deliver RSS, are useful research tools, as well as possible therapeutic agents. In this Minireview, we summarized the chemical strategies that have been used in the design of donors/precursors of hydrogen sulfide relevant RSS (including hydrogen sulfide, hydrogen polysulfides, persulfides, and S-nitroso-hydrogen sulfide). The potential problems of applying these strategies in biological settings are also discussed.

Inorganic hydrogen polysulfides: chemistry, chemical biology and detection.

Recent studies suggest that inorganic hydrogen polysulfides (H2 Sn , n ≥ 2) play important regulatory roles in redox biology. Modulation of their cellular levels could have potential therapeutic value. This review article focuses on our current understanding of the biosynthesis, biofunctions, fundamental physical/chemical properties, detection methods and delivery techniques of H2 Sn . LINKED ARTICLES: This article is part of a themed section on Chemical Biology of Reactive Sulfur Species. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.4/issuetoc.

TRPC6 contributes to LPS-induced inflammation through ERK1/2 and p38 pathways in bronchial epithelial cells.

receptor potential canonical (TRPC) channels are presently an emerging target for airway disorders. Recent evidence has indicated that TRPC6 as a member of the TRPC family plays an important role in airway inflammation, but its precise function in bronchial epithelial cells remains unclear. The aim of this study was to investigate the role of TRPC6 in Toll-like receptor 4 (TLR4)-mediated inflammation in human bronchial epithelial cells stimulated by endotoxin [lipopolysaccharide (LPS)]. Hyp9 is a simplified phloroglucinol derivative of hyperforin that highly selectively activates TRPC6 channels. The results show that the activation of TRPC6 by Hyp9 induced the production of interleukin (IL)-8 and IL-6. LPS was also able to induce the release of IL-8 and IL-6, which was significantly aggravated by Hyp9 and reduced by knockdown of TRPC6. Treatment with LPS not only chronically induced the expression of TRPC6 mRNA and protein in a TLR4-dependent manner but also acutely increased Ca2+ influx through TRPC6 channels. In addition, LPS-induced overexpression of TRPC6 and Ca2+ influx were associated with the phosphorylation of phosphatidylinositol 3-kinase (PI3K) and Akt. Importantly, TRPC6 was required for the activation of ERK1/2, p38, and NF-κB. In conclusion, these data reveal that LPS induced the overexpression of TRPC6 and TRPC6-dependent Ca2+ influx via the TLR4/PI3K/Akt pathway resulting in Ca2+ mobilization, which subsequently promoted the activation of ERK1/2, p38, and NF-κB and the inflammatory response in bronchial epithelial cells.

Recent Development of Hydrogen Sulfide Releasing/Stimulating Reagents and Their Potential Applications in Cancer and Glycometabolic Disorders.

As an important endogenous gaseous signaling molecule, hydrogen sulfide (H2S) exerts various effects in the body. A variety of pathological changes, such as cancer, glycometabolic disorders, and diabetes, are associated with altered endogenous levels of H2S, especially decreased. Therefore, the supplement of H2S is of great significance for the treatment of diseases containing the above pathological changes. At present, many efforts have been made to increase the in vivo levels of H2S by administration of gaseous H2S, simple inorganic sulfide salts, sophisticated synthetic slow-releasing controllable H2S donors or materials, and using H2S stimulating agents. In this article, we reviewed the recent development of H2S releasing/stimulating reagents and their potential applications in two common pathological processes including cancer and glycometabolic disorders.

A novel pH-controlled hydrogen sulfide donor protects gastric mucosa from aspirin-induced injury.

Hydrogen sulphide (H2 S) serves as a vital gastric mucosal defence under acid condition. Non-steroidal anti-inflammatory drugs (NSAIDs) are among widely prescribed medications with effects of antipyresis, analgesia and anti-inflammation. However, their inappropriate use causes gastric lesions and endogenous H2 S deficiency. In this work, we reported the roles of a novel pH-controlled H2 S donor (JK-1) in NSAID-related gastric lesions. We found that JK-1 could release H2 S under mild acidic pH and increase solution pH value. Intragastrical administration of aspirin (ASP), one of NSAIDs, to mice elicited significant gastric lesions, evidenced by mucosal festering and bleeding. It also led to infiltration of inflammatory cells and resultant releases of IL-6 and TNF-α, as well as oxidative injury including myeloperoxidase (MPO) induction and GSH depletion. In addition, the ASP administration statistically inhibited H2 S generation in gastric mucosa, while up-regulated cyclooxygenase (COX)-2 and cystathionine gamma lyase (CSE) expression. Importantly, these adverse effects of ASP were prevented by the intragastrical pre-administration of JK-1. However, JK-1 alone did not markedly alter the property of mouse stomachs. Furthermore, in vitro cellular experiments showed the exposure of gastric mucosal epithelial (GES-1) cells to HClO, imitating MPO-driven oxidative injury, decreased cell viability, increased apoptotic rate and damaged mitochondrial membrane potential, which were reversed by pre-treatment with JK-1. In conclusion, JK-1 was proved to be an acid-sensitive H2 S donor and could attenuate ASP-related gastric lesions through reconstruction of endogenous gastric defence. This work indicates the possible treatment of adverse effects of NSAIDs with pH-controlled H2 S donors in the future.

Inhibition of Methylglyoxal-Induced AGEs/RAGE Expression Contributes to Dermal Protection by N-Acetyl-L-Cysteine.

BACKGROUND/AIM: Accumulation of advanced glycation end products (AGEs) is a major cause of diabetes mellitus (DM) skin complications. Methylglyoxal (MGO), a reactive dicarbonyl compound, is a crucial intermediate of AGEs generation. N-acetyl-L-cysteine (NAC), an active ingredient of some medicines, can induce endogenous GSH and hydrogen sulfide generation, and set off a condensation reaction with MGO. However, there is rare evidence to show NAC can alleviate DM-induced skin injury through inhibition of AGEs generation or toxicity. The present study aimed to observe the effects of NAC on MGO-induced inflammatory injury and investigate the roles of AGEs and its receptor (RAGE) in NAC's dermal protection in human HaCaT keratinocytes. METHODS: The cells were exposed to MGO to simulate a high MGO status in diabetic blood or tissues. The content of AGEs in serum or cell medium was measured with ELISA. The protective effects of NAC against MGO-induce injury were evaluated by administration before MGO one hour, in virtue of cell viability, mitochondrial membrane potential, inflammation reaction, nuclear factor (NF)-κB activation, matrix metalloproteinase (MMP)-9 expression, as well as cellular behavioral function. RESULTS: We found the AGEs levels of patients with DM were elevated comparing with healthy volunteers. The in vitro AGEs generation was also able to be enhanced by the exposure of HaCaT cells to MGO, which reduced dose-dependently cellular viability, damaged mitochondrial function, triggered secretion of interleukin (IL)-6 and IL-8, activated NF-κB and upregulated MMP-9 expression. Furthermore, the exposure caused cellular adhesion and migration dysfunction, as well as collagen type I inhibition. Importantly, before the exposure to MGO, the preconditioning with NAC significantly attenuated MGO-induced AGEs generation, improved cellular viability and mitochondrial function, partially reversed the overexpression of proinflammatory factors and MMP-9, as well as the activation of NF-κB. Lastly, NAC blocked MGO-induced RAGE upregulation, and inhibition of RAGE with its neutralizing antibody significantly alleviated MGO-induced NF-κB activation, MMP-9 upregulation and inflammatory injury in HaCaT cells. CONCLUSION: The present work indicates the administration of NAC can prevent MGO-induced dermal inflammatory injury through inhibition of AGEs/RAGE signal, which may provide a basal support for the treatment of diabetic skin complications with NAC-containing medicines in the future.

[N-acetyl-L-cysteine reduces the ozone-induced lung inflammation response in mice].

In this study, we investigated the protective effect of the antioxidant N-acetyl-L-cysteine (NAC) on the lung inflammation caused by ozone (O3) exposure in mice. Thirty-two C57BL/6 mice were randomly divided into control group, O3 group, O3+NAC group and NAC group. Mice were exposed to O3 (1.0 ppm) or fresh air for 3 h on the day 1, day 3 and day 5, respectively. NAC (100 mg/kg) was intraperitoneally applied to the mice 1 h before each exposure. At 24 h after the 3-time exposure, the alveolar wall structure was severely damaged and the infiltrated inflammatory cells were apparent perivascularly and peribronchiolarly. Significant increases in the total white blood cell count, macrophage, lymphocyte and neutrophil counts, as well as total protein concentration were observed in the bronchoalveolar lavage fluid (BALF) (P < 0.05). The IL-6, IL-8 (P < 0.01) and MDA levels (P < 0.05) in the lung homogenates were elevated coherently. Administration of NAC could attenuate the alveolar wall structure damage induced by O3 exposure and reduce the amount of infiltrated inflammatory cells, total and differential leukocyte counts (P < 0.05), as well as the IL-6, IL-8 (P < 0.01) and MDA release (P < 0.05). Western blotting results showed that the O3 exposure up-regulated the p38 MAPK and NF-κB p65 protein expression in the lung tissue of mice (P < 0.05), which could be alleviated by NAC (P < 0.05). These results indicated that NAC could protect against O3-induced pulmonary inflammation in mice. The beneficial effect of NAC might be related with the p38 MAPK and NF-κB p65 signal pathway.