Protective effects of galangin against H2O2‐induced aging via the IGF‐1 signaling pathway in human dermal fibroblasts

Galangin, a natural flavonol, has anti‐inflammatory and antioxidative potential. However, the cytoprotective effects of galangin against oxidative‐induced aging in human fibroblasts have not been well studied. IGF‐1 signaling pathway is associated with the control of aging and longevity in human. The goal of this study was to investigate the effects of galangin on human skin fibroblast HS68 cells under H₂O₂ exposure to induce aging. In this study, we demonstrate that galangin could decrease the levels of pro‐inflammatory proteins and enhanced collagen formation through promoting the IGF‐1R pathway. Furthermore, aging markers such as senescence‐associated β‐galactosidase p53, p21^Cip1/WAF1, and p16^INK4A were upregulated under H₂O₂ exposure and galangin could reverse its effects. Taken together, these data indicated that anti‐inflammatory and antiaging activities of galangin may be mediated through the IGF‐1R signaling pathway. These findings may provide the evidence for galangin to develop as an antiwrinkle product on human skin.     

Inhibitory effect of Astragalus membranaceus root on matrix metalloproteinase‐1 collagenase expression and procollagen destruction in ultraviolet B‐irradiated human dermal fibroblasts by suppressing nuclear factor kappa‐B activity

Objectives The root of Astragalus membranaceus, regarded as a tonic in traditional Korean medicine, has been prescribed for long periods to treat chronic illness by boosting the immune system. Ultraviolet (UV) irradiation causes damage to skin connective tissue by degrading collagen, which is a major structural component of the extracellular matrix. Such damage is considered to be a cause of the wrinkling observed in premature ageing of the skin. This study has investigated the photo‐protective effect of A. membranaceus on UVB radiation‐induced activation of nuclear factor kappa‐B (NF‐κB) activity in human dermal fibroblasts. Methods Hs68 fibroblast cells cultured with various concentrations of A. membranaceus were exposed to UVB (40 mJ/cm²). Activation of NF‐κB P65 and expression of matrix metalloproteinase‐1 (MMP‐1) and type 1 procollagen were measured by Western blotting. Translocation of NF‐κB P65 and MMP‐1 regulation were also examined by immunocytochemistry. Key findings Western blotting and immunocytochemistry results showed that A. membranaceus inhibited UVB‐induced translocation of NF‐κB P65 and MMP‐1 expression. The data suggested that A. membranaceus restored type 1 procollagen synthesis by inhibiting NF‐κB P65 activity and MMP‐1 expression in UVB‐exposed human dermal fibroblasts. Conclusion A. membranaceus is a candidate for use in skin protection from UVB‐induced skin inflammation and photoageing.     

BENAZEPRIL, AN ANGIOTENSIN-CONVERTING ENZYME INHIBITOR, ALLEVIATES RENAL INJURY IN SPONTANEOUSLY HYPERTENSIVE RATS BY INHIBITING ADVANCED GLYCATION END-PRODUCT-MEDIATED PATHWAYS

• 1 Advanced glycation end‐products (AGE) and their receptors (RAGE) have been implicated in renal damage in diabetes. The aim of the present study was to investigate the effects of benazepril, an angiotensin‐converting enzyme inhibitor (ACEI), on the formation of AGE, the expression RAGE and other associated components in the oxidative stress pathway in spontaneously hypertensive rats (SHR).
• 2 Groups of SHR were treated with or without 10 mg/kg per day benazepril for 12 weeks. Systolic blood pressure (SBP) and angiotensin (Ang) II levels were evaluated in SHR and control Wistar‐Kyoto (WKY) rats. Renal function was investigated by determining levels of proteinuria and glomerulosclerosis. Furthermore, reactive oxygen species (ROS) in the rat renal cortex were analysed using an H₂O₂‐based hydroxyl radical‐detection assay and the renal content of AGE, RAGE, NADPH oxidase p47phox, nuclear factor (NF)‐κB p65, phosphorylated (p‐) NF‐κB p65, vascular cell adhesion molecule (VCAM)‐1 and transforming growth factor (TGF)‐β1 was determined by immunohistochemistry, quantitative real‐time polymerase chain reaction and western blot analysis.
• 3 Treatment with benazepril inhibited the formation of AngII, reduced SBP and alleviated renal lesions in SHR compared with both untreated SHR and control WKY rats. Benazepril treatment significantly suppressed the accumulation of AGE and expression of RAGE in the kidney of SHR. In addition, benazepril treatment reduced the upregulation of NADPH oxidase p47phox, ROS generation and NF‐κB p65, p‐NF‐κB p65, VCAM‐1 and TGF‐β1 expression in the kidney of SHR compared with both untreated SHR and control WKY rats.
• 4 The results of the present study provide new insights into the regulation by the renin–angiotensin system of AGE–RAGE, oxidative stress and nephropathy, increasing our understanding of the role of the RAS in nephropathy.

     

Nonylphenol regulates cyclooxygenase‐2 expression via Ros‐activated NF‐κB pathway in sertoli TM4 cells

The aim of this study was to investigate the signaling pathways involved in the cyclooxygenase (COX)‐2 regulation induced by nonylphenol (NP) in mouse testis Sertoli TM4 cells. Our results showed that treatment of TM4 cells with NP increased COX‐2 protein expression and interleukin‐6 (IL)‐6 and prostaglandin E2 (PGE2) secretion in a dose‐dependent manner. Pretreatment with reactive oxygen species (ROS) scavenger, N‐acetylcysteine (NAC), attenuated NP‐induced ROS production, COX‐2 expression, and IL‐6 and PGE2 release in TM4 cells. Exposure to NP stimulated activation of NF‐κB, whereas the NF‐κB inhibitor, pyrrolidine dithiocarbamate, attenuated NP‐enhanced COX‐2 expression and IL‐6 and PGE2 release in TM4 cells in a dose‐dependent manner. Furthermore, NAC blocked NP‐induced activation of NF‐κB. In addition, inhibition of COX‐2 mitigated NP‐induced IL‐6 release. In conclusion, NP induced ROS generation, activation of NF‐κB pathway, COX‐2 upregulation, and IL‐6 and PGE2 secretion in TM4 cells. NP may regulate COX‐2 expression via ROS‐activated NF‐κB pathway in Sertoli TM4 cells. © 2014 Wiley Periodicals, Inc. Environ Toxicol 30: 1144–1152, 2015.     

The natural flavonoid galangin ameliorates dextran sulphate sodium–induced ulcerative colitis in mice: Effect on Toll‐like receptor 4, inflammation and oxidative stress

This study was carried out to investigate the potential therapeutic effect of galangin, a promising active principle of honeybee propolis, in dextran sulphate sodium (DSS)–induced colitis in mice. We explored the possible underlying mechanisms for galangin action and the therapeutic benefit of adding galangin to the standard therapy sulphasalazine. A galangin dose of 40 mg/kg was selected based on a preliminary dose‐selection study for investigation in a 4‐week cyclical model of DSS‐induced colitis. Mice received 3% DSS in their drinking water during the first and third weeks and were administered the treatments (40 mg/kg galangin, 100 mg/kg sulphasalazine and a combination of 20 mg/kg galangin and 50 mg/kg sulphasalazine) daily starting from the second week. Galangin significantly ameliorated DSS‐induced histopathological alterations and tissue injury, down‐regulated Toll‐like receptor 4 expression, suppressed NF‐κB p65 activation, lowered inflammatory cytokine levels and demonstrated antioxidant effects. The combination of galangin and sulphasalazine at half doses yielded comparable results to either drug alone at full dose. This study highlights galangin as a promising therapy for colitis management.     

The antioxidant,cytotoxic, and antigenotoxic effects of galangin,puerarin, and ursolic acid in mammalian cells

Phenolic compounds not only contribute to the sensory qualities of fruits and vegetables but also exhibit several health protective properties. Galangin, puerarin, and ursolic acid are commonly used plant phenolics in folk medicine. In this study, the antioxidant capacities of galangin, puerarin, and ursolic acid by the trolox equivalent antioxidant capacity (TEAC) assay and the cytotoxic effects by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in V79 cells were investigated. The genotoxic potentials of galangin, puerarin, and ursolic acid were evaluated by micronucleus (MN) and alkaline COMET assays in human lymphocytes and in V79 cells. Galangin, puerarin, and ursolic acid (10, 100, 500, 1000, 2000, 5000, 10 000, and 20 000?μM) were found to have antioxidant activities at the studied concentrations. IC₅₀ values of galangin, puerarin, and ursolic acid in V79 cells were found to be 275.48?μM, 2503.712?μM, and 224.85?μM, respectively. Galangin, puerarin, and ursolic acid, at the all concentrations, have not exerted genotoxic effects and galangin, puerarin, and ursolic acid revealed a reduction in the frequency of MN and DNA damage induced by H₂O₂.     

Involvement of EGF receptor signaling and NLRP12 inflammasome in fine particulate matter‐induced lung inflammation in mice

Epidemiological studies have shown that exposure to ambient fine particulate matter (PM_2.5) is associated with respiratory diseases. Lung inflammation is a central feature of many pulmonary diseases, which can be induced by PM_2.5 exposure. However, the mechanisms underlying PM_2.5‐induced lung inflammation remain unclear. To characterize the role of epidermal growth factor receptor (EGFR) and inflammasome in PM_2.5‐induced lung inflammation in mice, 30 BALB/c mice were intrabroncheally instilled with saline and PM_2.5 suspension (4.0 mg/kg b.w.) for 5 consecutive days, respectively. Bronchoalveolar lavage (BAL) was conducted and BAL fluid (BALF) was collected. The levels of reactive oxygen species (ROS), inducible nitric oxide synthase (iNOS), epidermal growth factor (EGF), CXCL1, interleukin (IL)?1β, and IL‐18 in BALF were determined using ELISA. mRNA levels of IL‐6, IL‐1β, IL‐18, CXCL1, IL‐10, NLRP3, Caspase‐1, and NLRP12 in lung tissues were determined by RT‐PCR. Phospho‐EGFR (Tyr1068) and phospho‐Akt (Thr308) in lung tissues were examined using immunohistochemical staining and Western blotting, respectively. Protein levels of Caspase‐1, NLRP3, NF‐κB‐p52/p100, and NF‐κB‐p65 in bronchial epithelium were examined using immunohistochemical staining. It was shown that PM_2.5 exposure induced lung inflammation. Levels of total protein, ROS, iNOS, EGF, and CXCL1 and cell number in the BALF of mice exposed to PM_2.5 were markedly elevated relative to the control. mRNA levels of CXCL1, IL‐1β, and IL‐18 in lung tissues of PM_2.5‐exposed mice were increased in comparison with the control. However, level of NLRP12 mRNA in lung tissues of PM_2.5‐exposed mice was reduced. Phospho‐EGFR (Tyr1068) and phospho‐Akt (Thr308) levels in the lungs of PM_2.5‐instilled mice were higher than those in the lungs of the control. The protein levels of NF‐κB‐p52/p100 and NF‐κB‐p65 in bronchial epithelium of PM_2.5‐exposed mice were also increased compared with the control. This study suggests that EGF‐EGFR‐Akt‐NF‐κB signaling and NLRP12 inflammasome may be associated with PM_2.5‐induced lung inflammation in mice. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1121–1134, 2017.     

Inhibitory effect of galangin on atopic dermatitis-like skin lesions

Galangin is a member of the flavonol class of flavonoids having anti-inflammatory and anti-oxidative potential. Previously we reported the inhibitory effect of galangin on the mast cell-mediated allergic inflammation. For incremental research, we investigated the effects of galangin on atopic dermatitis (AD)-like skin lesions and underlying mechanisms of action. We established an atopic dermatitis model in BALB/c mice by repeated local exposure of house dust mite (Dermatophagoides farinae) extract (DFE) and 2,4-dinitrochlorobenzene (DNCB) to the ears. Repeated alternative treatment of DFE/DNCB caused AD-like skin lesions. Topical application of galangin reduced AD symptoms based on ear thickness and histopathological analysis, in addition to serum IgE and IgG2a levels. Galangin inhibited mast cell infiltration into the ear and serum histamine level. Galangin suppressed DFE/DNCB-induced expression of interleukin (IL)-4, IL-5, IL-13, IL-31, IL-32, and interferon (IFN)-γ in the ear tissue. To define the underlying mechanisms of action, tumor necrosis factor-α/IFN-γ-activated human keratinocytes (HaCaT) model was used. Galangin significantly inhibited the expression of cytokines and chemokine by the down-regulation of nuclear factor-κB and mitogen-activated protein kinases in HaCaT cells. Taken together, the results demonstrate that galangin inhibited AD-like symptoms, suggesting that galangin might be a candidate for the treatment of AD.     

PM2.5‐induced oxidative stress increases adhesion molecules expression in human endothelial cells through the ERK/AKT/NF‐κB‐dependent pathway

The aim of this study was to explore the intracellular mechanisms underlying the cardiovascular toxicity of air particulate matter (PM) with an aerodynamic diameter of less than 2.5 µm (PM_2.5) in a human umbilical vein cell line, EA.hy926. We found that PM_2.5 exposure triggered reactive oxygen species (ROS) generation, resulting in a significant decrease in cell viability. Data from Western blots showed that PM_2.5 induced phosphorylation of Jun N‐terminal kinase (JNK), extracellular signal regulatory kinase (ERK), p38 mitogen‐activated protein kinase (MAPK) and protein kinase B (AKT), and activation of nuclear factor kappa B (NF‐κB). We further observed a significant increase in expressions of intercellular adhesion molecule‐1 (ICAM‐1) and vascular adhesion molecule‐1 (VCAM‐1) in a time‐ and dose‐dependent manner. Moreover, the adhesion of monocytic THP‐1 cells to EA.hy926 cells was greatly enhanced in the presence of PM_2.5. However, N‐acetylcysteine (NAC), a scavenger of ROS, prevented the increase of ROS generation, attenuated the phosphorylation of the above kinases, and decreased the NF‐κB activation as well as the expression of ICAM‐1 and VCAM‐1. Furthermore, ERK inhibitor (U0126), AKT inhibitor (LY294002) and NF‐κB inhibitor (BAY11‐7082) significantly down‐regulated PM_2.5‐induced ICAM‐1 and VCAM‐1 expression as well as adhesion of THP‐1 cells, but not JNK inhibitor (SP600125) and p38 MAPK inhibitor (SB203580), indicating that ERK/AKT/NF‐κB is involved in the signaling pathway that leads to PM_2.5‐induced ICAM‐1 and VCAM‐1 expression. These findings suggest PM_2.5‐induced ROS may function as signaling molecules triggering ICAM‐1 and VCAM‐1 expressions through activating the ERK/AKT/NF‐κB‐dependent pathway, and further promoting monocyte adhesion to endothelial cells. Copyright © 2015 John Wiley & Sons, Ltd.     

A physiological concentration of glucocorticoid inhibits the pro-inflammatory cytokine-induced proliferation of adult rat cardiac fibroblasts: roles of extracellular signal-regulated kinase 1/2 and nuclear factor-κB

1. Inflammation‐induced proliferation of cardiac fibroblasts plays an important role in cardiac remodelling. Pharmacological doses of exogenous glucocorticoids (GC) are the most effective therapy for inflammatory diseases. Similarly, physiological concentrations of endogenous GC have recently been shown to have anti‐inflammatory effects. Therefore, the aim of the present study was to determine whether a physiological concentration of GC could inhibit pro‐inflammatory cytokine‐stimulated proliferation of cardiac fibroblasts and to explore the mechanisms involved. 2. Cardiac fibroblasts were isolated from adult male Sprague‐Dawley rats and cell proliferation was measured using a CCK‐8 kit. Western blotting was used to detect protein expression of extracellular‐regulated kinase (ERK) 1/2 and nuclear factor (NF)‐κB. 3. Cardiac fibroblast proliferation was significantly increased by tumour necrosis factor‐α, interleukin (IL)‐1β and angiotensin II and was accompanied by upregulated protein expression of ERK1/2 and NF‐κB. A physiological concentration of hydrocortisone (127 ng/mL) not only inhibited the proliferation of cardiac fibroblasts, but also suppressed activation of ERK1/2 and NF‐κB. These effects of hydrocortisone were abrogated by the glucocorticoid receptor (GR) antagonist RU‐486 (100 nmol/L). Furthermore, inflammation‐induced cardiac fibroblast proliferation was also blocked by the mitogen‐activated protein kinase kinase 1/2 inhibitor U0126 (100 nmol/L) and the NF‐κB inhibitor pyrrolidine dithiocarbamate (1 μmol/L). Cytokine‐induced ERK1/2 phosphorylation and cyclin D1 expression were attenuated by U0126, suggesting that the ERK1/2 and NF‐κB signalling pathways were involved in cardiac fibroblast proliferation. 4. In conclusion, the results of the present study indicate that a physiological concentration of hydrocortisone can inhibit inflammation‐induced proliferation of cardiac fibroblasts by preventing the activation of ERK1/2 and NF‐κB.     

Involvement of NF‐κB in the upregulation of cystathionine‐γ‐lyase,a hydrogen sulfide‐forming enzyme,and bladder pain accompanying cystitis in mice

Hydrogen sulfide (H₂S) is generated from l ‐cysteine by multiple enzymes including cystathionine‐γ‐lyase (CSE), and promotes nociception by targeting multiple molecules such as Ca_v3.2 T‐type Ca²⁺ channels. Bladder pain accompanying cyclophosphamide (CPA)‐induced cystitis in mice has been shown to involve the functional upregulation of the CSE/H₂S/Ca_v3.2 pathway. Therefore, we investigated whether NF‐κB, as an upstream signal of the CSE/H₂S system, contributes to bladder pain in mice with CPA‐induced cystitis. Bladder pain‐like nociceptive behaviour was observed in CPA‐treated mice, and referred hyperalgesia was evaluated by the von Frey test. Isolated bladder weights were assessed to estimate bladder swelling, and protein levels were measured by Western blotting. CPA, administered intraperitoneally, induced nociceptive behaviour, referred hyperalgesia and increased bladder weights in mice. β‐Cyano‐l ‐alanine, a reversible selective CSE inhibitor, prevented CPA‐induced nociceptive behaviour, referred hyperalgesia, and, in part, increases in bladder weight. CPA markedly increased phosphorylated NF‐κB p65 levels in the bladder, an effect that was prevented by pyrrolidine dithiocarbamate (PDTC), an NF‐κB inhibitor. PDTC and curcumin, which inhibits NF‐κB signals, abolished CPA‐induced nociceptive behaviour, referred hyperalgesia and, in part, increases in bladder weight. CPA caused the overexpression of CSE in the bladder, and this was prevented by PDTC or curcumin. The CPA‐induced activation of NF‐κB signals appeared to cause CSE overexpression in the bladder, contributing to bladder pain and in part swelling, possibly through H₂S/Ca_v3.2 signaling. Therefore, NF‐κB‐inhibiting compounds including curcumin may be useful for the treatment of cystitis‐related bladder pain.     

Photoprotective Potential of Anthocyanins Isolated from Acanthopanax divaricatus Var. albeofructus Fruits against UV Irradiation in Human Dermal Fibroblast Cells

Ultraviolet (UV) A penetrates deeply into the skin and induces the generation of reactive oxygen species (ROS) causing damage to fibroblasts, which leads to aging of the skin. However, the body has developed an antioxidant defence system against the harmful effects of ROS. Enzymes such as superoxide dismutase (SOD) and catalase (CAT) play critical roles on the removal of excess ROS in living organisms. In this study, the antioxidant activities of anthocyanins (cyanidin 3-galactoside and cyanidin 3-lathyroside) from Acanthopanax divaricatus var. albeofructus (ADA) fruits were investigated by xylenol orange, thiobarbituric acid reactive substances (TBARS), and antioxidant enzyme assay. As a result, generation of H₂O₂ and lipid peroxide induced by UVA-irradiation in human dermal fibroblast (HDF-N) cells was reduced by treatment of anthocyanins. Also, augmented enzyme (SOD and CAT) activities were observed in UVA-irradiated cells when treated with anthocyanin. In conclusion, the results obtained show that anthocyanins from ADA fruits are potential candidates for the protection of fibroblast against the damaging effects of UVA irradiation. Furthermore, anthocyanin may be a good candidate for antioxidant agent development.     

MiR‐146a regulates PM1‐induced inflammation via NF‐κB signaling pathway in BEAS‐2B cells

Exposure to particulate matter (PM) leads to kinds of cardiopulmonary diseases, such as asthma, COPD, arrhythmias, lung cancer, etc., which are related to PM‐induced inflammation. We have found that PM_2.5 (aerodynamics diameter <2.5 µm) exposure induces inflammatory response both in vivo and in vitro. Since the toxicity of PM is tightly associated with its size and components, PM₁ (aerodynamics diameter <1.0 µm) is supposed to be more toxic than PM_2.5. However, the mechanism of PM₁‐induced inflammation is not clear. Recently, emerging evidences prove that microRNAs play a vital role in regulating inflammation. Therefore, we studied the regulation of miR‐146a in PM₁‐induced inflammation in human lung bronchial epithelial BEAS‐2B cells. The results show that PM₁ induces the increase of IL‐6 and IL‐8 in BEAS‐2B cells and up‐regulates the miR‐146a expression by activating NF‐κB signaling pathway. Overexpressed miR‐146a prevents the nuclear translocation of p65 through inhibiting the IRAK1/TRAF6 expression, and downregulates the expression of IL‐6 and IL‐8. Taken together, these results demonstrate that miR‐146a can negatively feedback regulate PM₁‐induced inflammation via NF‐κB signaling pathway in BEAS‐2B cells.     

Attenuation of liver pro-inflammatory responses by Zingiber officinale via inhibition of NF-kappa B activation in high-fat diet-fed rats

Abstract: The aim of this study was to investigate whether treatment with a ginger (Zingiber officinale) extract of high‐fat diet (HFD)‐fed rats suppresses Nuclear factor‐kappa B (NF‐κB)‐driven hepatic inflammation and to subsequently explore the molecular mechanisms in vitro. Adult male Sprague‐Dawley rats were treated with an ethanolic extract of Zingiber officinale (400 mg/kg) along with a HFD for 6 weeks. Hepatic cytokine mRNA levels, cytokine protein levels and NF‐κB activation were measured by real‐time PCR, Western blot and an NF‐κB nuclear translocation assay, respectively. In vitro, cell culture studies were carried out in human hepatocyte (HuH‐7) cells by treatment with Zingiber officinale (100 μg/mL) for 24 hr prior to interleukin‐1β (IL‐1β, 8 ng/mL)‐induced inflammation. We showed that Zingiber officinale treatment decreased cytokine gene TNFα and IL‐6 expression in HFD‐fed rats, which was associated with suppression of NF‐κB activation. In vitro, Zingiber officinale treatment decreased NF‐κB‐target inflammatory gene expression of IL‐6, IL‐8 and serum amyloid A1 (SAA1), while it suppressed NF‐κB activity, IκBα degradation and IκB kinase (IKK) activity. In conclusion, Zingiber officinale suppressed markers of hepatic inflammation in HFD‐fed rats, as demonstrated by decreased hepatic cytokine gene expression and decreased NF‐κB activation. The study demonstrates that the anti‐inflammatory effect of Zingiber officinale occurs at least in part through the NF‐κB signalling pathway.     

Protective effects of hepatocyte growth factor gene overexpression against hydrogen peroxide‐induced apoptosis in mesenchymal stem cells

Hepatocyte growth factor (HGF) has recently been reported to exhibit antioxidant and antiapoptotic effects. Therefore, we investigated the effect of overexpression of HGF gene in H₂O₂‐treated mesenchymal stem cells (MSCs). HGF‐overexpression increased the cell viability from 50% to 84%, decreased the population of apoptotic cells from 20% to 16%, and decreased the intracellular reactive oxygen species (ROS) levels from 127% to 100% in cells treated with H₂O₂. HGF suppression decreased the cell viability from 58% to 36%, increased the population of apoptotic cells from 23 to 81%, and increased the intracellular ROS levels from 181% to 240% in cells exposed to H₂O₂. HGF‐overexpression also reduced the expression levels of proapoptotic proteins in MSCs treated with H₂O₂. Phosphorylation of extracellular signal‐regulated kinases, c‐Jun amino‐terminal kinases, and p38, which was induced by H₂O₂, decreased in MSCs overexpressing the HGF gene. Taken together, our results suggest that HGF has a protective effect on H₂O₂‐induced apoptosis in MSCs.     

Epidermal growth factor receptor (EGFR)—MAPK—nuclear factor(NF)‐κB—IL8: A possible mechanism of particulate matter(PM) 2.5‐induced lung toxicity

Airway inflammation plays a central role in the pathophysiology of diverse pulmonary diseases. In this study, we investigated whether exposure to particulate matter (PM) 2.5, a PM with an aerodynamic diameter of less than 2.5 µm, enhances inflammation‐related toxicity in the human respiratory system through activation of the epidermal growth factor receptor (EGFR) signaling pathway. Through cytokine antibody array analysis of two extracts of PM_2.5 [water (W‐PM_2.5) and organic (O‐PM_2.5) soluble extracts] exposed to A549 (human alveolar epithelial cell), we identified eight cytokines changed their expression with W‐PM_2.5 and three cytokines with O‐PM_2.5. Among them, epidermal growth factor (EGF) was commonly up‐regulated by W‐PM_2.5 and O‐PM_2.5. Then, in both groups, we can identify the increase in EGF receptor protein levels. Likewise, increases in the phosphorylation of ERK1/2 MAP kinase and acetylation of nuclear factor(NF)‐κB were detected. We also detected an increase in IL‐8 that was related to inflammatory response. And using the erlotinib as an inhibitor of EGFR, we identified the erlotinib impaired the phosphorylation of EGFR, ERK1/2, acetylation of NF‐κB proteins and decreased IL‐8. Furthermore, at in vivo model, we were able to identify similar patterns. These results suggest that PM_2.5 may contribute to an abnormality in the human respiratory system through EGFR, MAP kinase, NF‐κB, and IL‐8 induced toxicity signaling. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1628–1636, 2017.