장기간 운동이 마우스 조직별 heme oxygenase-1 발현에 미치는 영향

김시영 ( Si Young Kim ) 한국운동생리학회(구-한국운동과학회) 2010 운동과학 Vol.19 No.1

Heme oxygenase-1 (HO-1)은 산화적인 자극을 포함한 다양한 외부 스트레스에 대한 조직세포의 적응 및 방어에 중요한 역할을 담당하는 항산화효소이다. 본 연구의 목적은 마우스의 다양한 조직에서 HO-1의 발현 차이는 물론 장기간의 운동에 의한 조절 가능성을 알아보는데 있다. 연구에 사용된 24마리의 ICR계 마우스는 각각 8마리씩 세 그룹 [control group (CONT, n=8), low-intensity exercise group (LIE, n=8), high-intensity exercise group (HIE, n=8)]으로 나누어 졌으며, 16주간의 트레드밀 운동프로그램 후 골격근, 대장, 심장, 폐, 간 그리고 뇌를 분리하여 분석하였다. CONT에서 안정시 마우스 조직별 HO-1 발현량을 분석한 결과, 간 조직에서의 발현량이 가장 높았으며, 이어서 대장, 폐, 심장, 골격근 그리고 뇌 순으로 발현량의 유의한 차이가 나타났다. 16주간 트레이닝 후 비교그룹 (CONT)에 비해 트레이닝 그룹 (HIE, LIE)의 골격근, 대장 및 간에서 HO-1의 발현량이 유의하게 증가된 (p<.01, p<.001) 반면, 심장, 폐 그리고 뇌 조직에서는 그룹 간 발현차이가 나타나지 않았다. 이상의 결과를 바탕으로 결론을 내리면, 안정된 상태에서 마우스 조직에 따라 발현되는 HO-1 단백질량은 조직 사이에 유의한 차이가 있으며, 골격근, 대장 그리고 간 조직에서의 HO-1 발현량은 반복된 운동으로 증가시킬 수 있었다. Heme oxygenase (HO)-1, involved in the heme degradation process, is upregulated by a wide array of stimuli and has antioxidant, anti-inflammatory and other cytoprotective functions. The aim of this study was to investigate the difference and effect of long-term exercise on HO-1 expression among mouse tissues. The study carried out on twenty-four ICR mice. All mice participated in this study which consisted of three groups [control group (CONT, n=8), low-intensity exercise group (LIE, n=8), high-intensity exercise group (HIE, n=8)]. Mice were euthanized after 16 weeks of training periods and tissues (skeletal muscle, colon, heart, lung, liver, and brain) were removed. As a result of analyzed difference of HO-1 expression among tissues, liver topped the list, followed by colon, lung, heart, skeletal muscle, and brain (p<.001). In case of skeletal muscle, colon, and liver, after training for 16 weeks, HO-1 expression in HIE and/or LIE dramatically increased in comparison with CONT (p<.01, p<.001). On the other hand, no significant differences in the heart, lung, and brain were found between all groups. Taken together, we conclude that level of HO-1 expression is different between mouse tissues and long-term regular exercise can enhance the levels of HO-1 expression in skeletal muscle, colon, and liver.

Defense mechanism of heme oxygenase-1 against cytotoxic and receptor activator of nuclear factor-&kgr;B ligand inducing effects of hydrogen peroxide in human periodontal ligament cells

Pi, S.-H.,Kim, S.-C.,Kim, H.-T.,Lee, H.-J.,Lee, S.-K.,Kim, E.-C. Blackwell Publishing Ltd 2007 Journal of periodontal research Vol.42 No.4

<P>Background and Objective: </P><P>Although induction of heme oxygenase-1 by H<SUB>2</SUB>O<SUB>2</SUB> has been reported, the protective role of heme oxygenase-1 against the cytotoxic and osteoclastogenic effects of H<SUB>2</SUB>O<SUB>2</SUB> have not been elucidated in human periodontal ligament cells. The aim of this work was to investigate the defense mechanism of heme oxygenase-1 on H<SUB>2</SUB>O<SUB>2</SUB>-induced cytotoxicity and to analyze the expression of receptor activator of nuclear factor-&kgr;B ligand (RANKL) and osteoprotegerin as markers for osteoclast differentiation in periodontal ligament cells.</P><P>Material and Methods: </P><P>Using human periodontal ligament cells, cytotoxicity was measured by the 3,4,5-dimethylthiazol-2-yl-2,5-diphenyl tetrazolium bromide (MTT) assay, and expression of heme oxygenase-1, RANKL, and osteoprotegerin mRNA was determined by reverse transcription–polymerase chain reaction.</P><P>Results: </P><P>H<SUB>2</SUB>O<SUB>2</SUB> produced a cytotoxic effect by reducing the cell viability and enhancing the expression of heme oxygenase-1 and RANKL mRNAs in a concentration- and time-dependent manner. Additional experiments revealed that heme oxygenase-1 inducer (hemin), a membrane-permeable cGMP analog (8-bromo-cGMP), carbon monoxide, extracellular signal-regulated kinase, p38 mitogen-activated protein kinase inhibitor, protein kinase inhibitor (KT5823), and nuclear factor-&kgr;B inhibitor (pyrrolidine dithiocarbamate) also blocked the effects of H<SUB>2</SUB>O<SUB>2</SUB> on cell viability and RANKL mRNA expression in periodontal ligament cells.</P><P>Conclusion: </P><P>These data suggest that heme oxygenase-1 induction plays a protective role in periodontal ligament cells against the cytotoxic and RANKL-inducing effects of H<SUB>2</SUB>O<SUB>2</SUB>, through multiple signaling pathways.</P>

Isolation of Megastigmane Sesquiterpenes from the Silkworm (Bombyx mori L.) Droppings and Their Promotion Activity on HO-1 and SIRT1

Ji-Hae Park,Do-Gyeong Lee,Seung-Woo Yeon,Hyuk-Sang Kwon,Jong-Hee Ko,Dong-Jin Shin,Han-Sol Park,Yong-Soon Kim,Myun-Ho Bang,NAM-IN BAEK 대한약학회 2011 Archives of Pharmacal Research Vol.34 No.4

The silkworm (Bombyx mori L.) droppings were extracted with 80% aqueous MeOH, and the concentrated extract was partitioned in succession with EtOAc, n-BuOH, and H_2O. From the EtOAc fraction, five megastigmane sesquiterpenes were isolated through repeated silica gel and ODS column chromatography. According to the results of spectroscopic data, such as NMR, MS, and IR, the chemical structures of the isolated compounds were determined as (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (1), (S)-dehydrovomifoliol (2), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (3), (3S,5R,6S,7E)-3,5,6-trihydroxy-7-megastigmen-9-one (4), (6R,9R)-9-hydroxy-4-megastigmen-3-one (5). Compounds 2 through 5 were isolated for the first time from silkworm droppings. GC/MS analysis indicated silkworm powder contained compound 3, and mulberry leaves contained compound 4. Compounds 1 and 5 increased the expression of heme oxygenase-1 and SIRT1 in HepG2 and HEK239 cells, respectively. Heme oxygenase-1 is considered to be an antioxidant enzyme that catabolizes heme to carbon monoxide, free iron and biliverdin, while SIRT1 is the mammalian homologue of the yeast silent information regulator (Sir)-2, which are involved in the suppression of inflammatory mediators or factors that may be used to improve atopy-related symptoms.

Non-canonical vs. Canonical Functions of Heme Oxygenase-1 in Cancer

Jagadeesh Achanta Sri Venakata,Fang Xizhu,김성훈,Guillen-Quispe Yanymee N.,Zheng Jie,서영준,Kim Su-Jung 대한암예방학회 2022 Journal of cancer prevention Vol.27 No.1

Heme oxygenase-1 (HO-1) is a critical stress-responsive enzyme that has antioxidant and anti-inflammatory functions. HO-1 catalyzes heme degradation, which gives rise to the formation of carbon monoxide (CO), biliverdin, and iron. The upregulation of HO-1 under pathological conditions associated with cellular stress represents an important cytoprotective defense mechanism by virtue of the anti-oxidant properties of the bilirubin and the anti-inflammatory effect of the CO produced. The same mechanism is hijacked by premalignant and cancerous cells. In recent years, however, there has been accumulating evidence supporting that the upregulation of HO-1 promotes cancer progression, independently of its catalytic activity. Such non-canonical functions of HO-1 are associated with its interaction with other proteins, particularly transcription factors. HO-1 also undergoes post-translational modifications that influence its stability, functional activity, cellular translocation, etc. HO-1 is normally present in the endoplasmic reticulum, but distinct subcellular localizations, especially in the nucleus, are observed in multiple cancers. The nuclear HO-1 modulates the activation of various transcription factors, which does not appear to be mediated by carbon monoxide and iron. This commentary summarizes the non-canonical functions of HO-1 in the context of cancer growth and progression and underlying regulatory mechanisms.

Prenylated Chalcone from Sophora flavescens Suppresses Th2 Chemokine Expression Induced by Cytokines via Heme Oxygenase-1 in Human Keratinocytes

Choi, Byung-Min,Oh, Gi-Su,Lee, Jang-Won,Mok, Ji-Ye,Kim, Dae-Keun,Jeong, Seung-Il,Jang, Seon-Il 대한약학회 2010 Archives of Pharmacal Research Vol.33 No.5

We recently reported the inhibitory effect of an oral administration of a Sophora flavescens Aiton methanol extract on the development of atopic dermatitis in the NC/Nga model mice. Heme oxygenase (HO)-1 has recently emerged as an important cytoprotective enzyme against oxidative stress and inflammatory responses in many cell types. The aim of this study was to investigate the possible mechanism by which prenylated chalcone (PC, 7,9,2',4'-tetrahydroxy-8-isopentenyl-5-methoxychalcone), a natural product isolated from S. flavescens, inhibited cytokine-induced Th2 chemokine expression in human keratinocytes, HaCaT cells. The level of chemokine expression was measured by reverse transcription-polymerase chain reaction and HO-1 study was performed by Western blot analysis. Interferon-${\gamma}$ (IFN-${\gamma}$) and tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$)-induced thymus- and activation-regulated chemokine (TARC/CCL17), macrophage-derived chemokine (MDC/CCL22), cutaneous T-cell attracting chemokine (CTACK/CCL27) expression in a dose-dependent manner. Interestingly, PC significantly suppressed IFN-${\gamma}$ and TNF-${\alpha}$-induced TARC/CCL17, MDC/CCL22 and CTACK/CCL27 expression via the induction of heme oxygenase (HO)-1. This suppression was completely restored by HO-1 siRNA, suggesting a direct role of HO-1 for the suppressive effect. Furthermore, exogenous CO, but not other end products of HO-1 activity, also suppressed IFN-${\gamma}$ and TNF-${\alpha}$-induced TARC/CCL17, MDC/CCL22 and CTACK/CCL27 expression. These results demonstrate that prenylated chalcone induces HO-1 expression, which in turn HO-1 and/or CO suppresses Th2 chemokine expressions induced by cytokines in human HaCaT cells.

Oxymatrine inhibits the pyroptosis in rat insulinoma cells by affecting nuclear factor kappa B and nuclear factor (erythroid-derived 2)-like 2 protein/heme oxygenase-1 pathways

Jingying Gao,Lixia Xia,Yuanyuan Wei 대한약리학회 2022 The Korean Journal of Physiology & Pharmacology Vol.26 No.3

As the mechanism underlying glucose metabolism regulation by oxymatrine is unclear, this study investigated the effects of oxymatrine on pyroptosis in INS-1 cells. Flow cytometry was employed to examine cell pyroptosis and reactive oxygen species (ROS) production. Cell pyroptosis was also investigated via transmission electron microscopy and lactate dehydrogenase (LDH) release. Protein levels were detected using western blotting and interleukin (IL)-1β and IL-18 secretion by enzyme-linked immunosorbent assay. The caspase-1 activity and DNA-binding activity of nuclear factor kappa B (NF-κB) and nuclear factor (erythroid-derived 2)-like 2 protein (Nrf2) were also assessed. In the high glucose and high fat-treated INS-1 cells (HG + PA), the caspase-1 activity and LDH content, as well as Nod-like receptor family pyrin domain containing 3, Gsdmd-N, caspase-1, apoptosis-associated specklike protein containing a CARD, IL-1β, and IL-18 levels were increased. Moreover, P65 protein levels increased in the nucleus but decreased in the cytoplasm. Oxymatrine attenuated these effects and suppressed high glucose and high fat-induced ROS production. The increased levels of nuclear Nrf2 and heme oxygenase-1 (HO-1) in the HG + PA cells were further elevated after oxymatrine treatment, whereas cytoplasmic Nrf2 and Keleh-like ECH-associated protein levels decreased. Additionally, the elevated transcriptional activity of p65 in HG + PA cells was reduced by oxymatrine, whereas that of Nrf2 increased. The results indicate that the inhibition of pyroptosis in INS- 1 cells by oxymatrine, a key factor in its glucose metabolism regulation, involves the suppression of the NF-κB pathway and activation of the Nrf2/HO-1 pathway.

Involvement of Peroxynitrite in NO Donor-Induced HO-1 Expression in Rat Articular Chondrocytes

Ju Dong Song(송주동),Kang Mi Kim(김강미),Jong Min Kim(김종민),Young Hyun Yoo(유영현),Young Chul Park(박영철) 한국생명과학회 2011 생명과학회지 Vol.21 No.4

Nitric oxide (NO) donors는 heme oxygenase-1 (HO-1)의 강력한 유도제이다. 그러나 NO donors에 의한 HO-1의 발현이 NO donor에 의해 방출되는 NO에 의한 직접적인 영향인지는 불분명하다. 본 연구에서 흰쥐의 무릎으로부터 분리 배양한 관절연골세포에서 HO-1의 발현에 NO donors의 영향을 조사하였다. NO donors(SIN-1, SNAP 그리고 SNP)는 HO-1의 mRNA와 단백질의 합성을 크게 증가시켰다. 그리고 NO의 표적 분자인 guanylate cyclase와 protein kinase G의 관련성을 살펴본 결과, NO donors에 의한 Nrf2와 HO-1의 발현증가와는 무관한 것으로 보였다. 흥미롭게도, NO scavenger인 carboxy-PTIO와 SOD mimetic TEMPOL은 NO donors에 의한 HO-1의 발현을 억제하였다. 게다가, peroxynitrite scavenger인 MnTBAP에 의해서도 Nrf2와 HO-1의 발현이 완전히 억제되었다. Peroxynitrite는 NO와 superoxide의 반응에 의해 세포 내에서 자연적으로 형성되는 물질이므로 peroxynitrite가 관절연골세포에서 HO-1의 발현에 직접적인 영향을 주는지를 관찰하였다. 관절연골세포에 peroxynitrite를 처리한 결과, 시간과 농도 의존적으로 Nrf2와 HO-1의 발현을 크게 증가시켰다. 본 실험 자료는 NO donors에 의한 HO-1의 발현증가는 방출되는 NO의 직접적인 영향이라기 보다는 NO와 superoxide의 반응으로 형성되는 peroxynitrite에 의해 유도된다는 것을 시사한다. Nitric oxide (NO) donors are a potent inducer of heme oxygenase-1 (HO-1). However, it is unclear whether or not HO-1 expression induced by NO donors is a direct consequence of NO released by NO donors. Here, we investigated the effects of NO donors on the expression of HO-1 in primary rat articular chondrocytes. NO donors (SIN-1, SNAP, and SNP) significantly induced the accumulation of HO-1 protein accompanied by an increase in HO-1 mRNA. NO donor-induced HO-1 expression exerted cytoprotection against NO and/or superoxide-induced cell death. Guanylate cyclase signaling was not associated with Nrf2 and HO-1 expression in NO donor-treated chondrocytes. Interestingly, NO scavenger carboxy-PTIO and SOD mimetic TEMPOL markedly inhibited NO donor-induced HO-1 expression in chondrocytes. In addition, NO donor-induced HO-1 expression was completely abrogated by the peroxynitrite scavenger MnTBAP. Since peroxynitrite can be physiologcally formed in the cell through reaction of NO with superoxide, we analyzed whether or not peroxynitrite could directly induce HO-1 expression in chondrocytes. Peroxynitrite treatment in chondrocytes evoked dose-and time-dependent Nrf2 and HO-1 expression. These results indicate that HO-1 expression induced by NO donors in rat articular chondrocytes is due to NO-mediated peroxynitrite rather than NO.

Effect of NADPH Oxidase Inhibition on Heme Oxygenase-1 Expression in Human Hepatoma Cell Line HepG2

이상권(Sang Kwon Lee),김강미(Kang Mi Kim),박광훈(Kwang Hoon Park),박영철(Young Chul Park) 한국생명과학회 2011 생명과학회지 Vol.21 No.11

CoPP는 다양한 세포에서 HO-1의 유전자 발현과 활성을 증가시키는 강력한 유도제로 알려져 있다. HO-1는 세포 및 조직의 손상을 보호한다는 연구가 활발히 진행되고 있으나, 그 작용 기전에 대해서는 아직 잘 모르고 있다. 본 논문에서는 porphyrin 계열의 CoPP의 자극에 의해 유도되는 HO-1 유전자 발현에서 NADPH oxidase의 활성이 미치는 영향을 인간 간암세포주 HepG2에서 조사하였다. 배양 중인 HepG2 세포에서 CoPP는 HO-1의 발현을 농도의존적으로 증가시키는 것을 확인하였다. NADPH oxidase 저해제로 잘 알려져 있는 DPI를 전처리한 후 CoPP로 자극한 세포에서는 HO-1의 발현이 강력하게 억제되는 것으로 나타났다. DPI의 이런 억제 효과가 HO-1의 전사 조절인자 Nrf2의 활성에도 영향을 줄 수 있기 때문에 DPI를 전처리 한 후 CoPP 자극에 의한 Nrf2의 핵으로의 이동을 분석하였다. 그 결과, DPI는 CoPP에 의해 유도되는 Nrf2의 핵으로의 이동과 세포 내 존재하는 양을 감소시키는 것을 확인하였다. 다른 HO-1 발현 유도제로 알려져 있는 hemin에 의한 자극의 경우에도 DPI는 HepG2 세포의 HO-1의 발현을 억제하는 효과를 나타내었다. 그리고, p47<SUP>phox</SUP>에 대한 siRNA를 사용하여 효과적으로 p47<SUP>phox</SUP> 유전자 발현을 knockdown 시켜서 NADPH oxidase의 활성을 억제시키는 방법을 사용하였다. 그 결과, p47<SUP>phox</SUP> silencing한 세포에 CoPP를 처리한 경우는 control siRNA를 처리한 세포와 비교할 때 HO-1 발현이 현저히 감소됨을 관찰할 수 있었다. 마지막으로, 세포 내 ROS 생성을 억제하는 GSHmee가 처리된 세포에서는 CoPP나 hemin이 Nrf2의 활성을 증가시키지 못하였고, 그 결과 HO-1의 발현을 유도하지 못하는 것을 알 수 있었는데, 이는 ROS가 CoPP나 hemin에 의한 HO-1 유전자 발현 과정에 중요한 역할을 한다는 것을 의미한다. 이를 종합해 볼 때, 인간 간암세포주 HepG2에서 CoPP나 hemin의 자극에 의한 HO-1 유전자의 발현에는 NADPH oxidase의 활성이 요구된다는 것을 알 수 있고, 그 활성은 세포 내 ROS를 생성시키는 것으로 역할을 한다고 여겨진다. Heme oxygenase-1 (HO-1) is a stress-responsive protein that is known to regulate cellular functions such as cell proliferation, inflammation, and apoptosis. In this study, we investigated the role of NADPH oxidase on the expression of HO-1 in human liver hepatoma cell line HepG2. Diphenyleneiodonium (DPI), an NADPH oxidase inhibitor, markedly inhibited HO-1 expression and the nuclear translocation of transcription factor Nrf2 in cobalt protoporphyrin (CoPP) or hemin-treated HepG2 cells. Similarly, the knockdown of p47<SUP>phox</SUP>, a cytosolic factor for NADPH oxidase activity, by siRNA inhibited the CoPP-induced expression of HO-1. In addition, GSHmee, an intracellular anti-oxidant, blocked the expression of HO-1 in CoPP-treated cells. Based on these results, we conclude that the blockage of NADPH oxidase with DPI or p47<SUP>phox</SUP> siRNA inhibits CoPP-induced HO-1 expression in HepG2 cells, and also suggest that the expression of HO-1 in CoPP-induced HepG2 cells is associated with increase of intracellular ROS by NADPH oxidase activity.

15d-PGJ2 inhibits NF-kB and AP-1-mediated MMP-9 expression and invasion of breast cancer cell by means of a heme oxygenase-1-dependent mechanism

장혜연,On-Yu Hong,Hyun Jo Youn,김민걸,Cheorl-Ho Kim,정성후,Jong-Suk Kim 생화학분자생물학회 2020 BMB Reports Vol.53 No.4

Activation of peroxisome proliferator-activated receptor  (PPAR) serves as a key factor in the proliferation and invasion of breast cancer cells and is a potential therapeutic target for breast cancer. However, the mechanisms underlying this effect remain largely unknown. Heme oxygenase-1 (HO-1) is induced and overexpressed in various cancers and is associated with features of tumor aggressiveness. Recent studies have shown that HO-1 is a major downstream target of PPAR. In this study, we investigated the effects of induction of HO-1 by PPAR on TPAinduced MMP-9 expression and cell invasion using MCF-7 breast cancer cells. TPA treatment increased NF-B /AP-1 DNA binding as well as MMP-9 expression. These effects were significantly blocked by 15d-PGJ2, a natural PPAR ligand. 15d-PGJ2 induced HO-1 expression in a dose-dependent manner. Interestingly, HO-1 siRNA significantly attenuated the inhibition of TPA-induced MMP-9 protein expression and cell invasion by 15d-PGJ2. These results suggest that 15d-PGJ2 inhibits TPA-induced MMP- 9 expression and invasion of MCF-7 cells by means of a heme oxygenase-1-dependent mechanism. Therefore, PPAR/HO-1 signaling- pathway inhibition may be beneficial for prevention and treatment of breast cancer.

Heme Oxygenase-1 is Involved in the Down-regulation of Nuclear Transcription Factor κB Activation in the Colonic Epithelium During Inflammation

윤기중(Ki Jung Yun),김유림(Yu Rim Kim),이홍재(Heung Jae Lee),김경숙(Kyoung Suk Kim),권영미(Young-Mi Kwon),최민규(Min Kyu Choi),오재민(JaeMin Oh),정연태(Yeun Tai Chung) 대한해부학회 2004 Anatomy & Cell Biology Vol.37 No.6

HO-1은 스트레스에 의해 유도되는 효소로 그 항염증작용에 대한 기전은 거의 밝혀지지 않고 있다. NF-κB 활성은 만성 염증성 대장염을 일으키는데 관여하는 매우 중요한 인자이다. 우리는 대장염에서 NF-κB 활성과 HO-1 사이의 관계에 대하여 조사하였다. 정상인에 비하여 염증성 대장염이나 acute pesudomembranous colitis를 가진 환자에서 대장의 상피조직의 HO-1의 발현이 현저히 감소하였다. 또한 사람 대장상피세포주인 HT-29세포에서 TNF-α와 IL-1β 등의 사이토카인들은 HO-1의 발현을 억제하였다. HO-1의 유도제인 CoPPIX는 TNF-α에 의한 NF-κB 활성을 억제하였다. 또한 HO-1의 대사물질인 일산화탄소와 빌리루빈 역시 TNF-α에 의한 NF-κB 활성을 억제하였다. 그러나 다른 대사물질인 철은 TNF-α에 의한 NF-κB 활성을 억제하는데 아무런 효과가 없었다. 재미있게도 CoPPIX는 TNBS에 의해 유도된 만성 대장염을 현저히 개선하였고 궤양성 대장염의 동물모델에서도 NF-κB 활성을 억제하였다. 이상의 결과로 CoPPIX는 NF-κB 활성의 억제를 통해서 TNBS에 의해 유도된 만성 대장염의 증상들을 개선시킨다고 생각되었고 HO-1은 만성 염증성 대장염을 치료하는데 중요한 타겟물질이라고 생각하였다. Heme oxygenase-1 (HO-1) is a stress-inducible enzyme with anti-inflammatory activity, but the mechanisms underlying this activity are incompletely understood. Nuclear transcription factor κB (NF-κB) activation is an important factor in the pathogenesis of inflammatory bowel disease (IBD). We investigated the suppressive effects of HO-1 on the activation of NF-κB by pro-inflammatory cytokines in cultured colonic epithelial cells and by trinitrobenzene sulfonic acid (TNBS) in the colon of mice. The expression level of HO-1 in the colonic epithelium of a patient with inflammatory bowel disease and pseudomembranous colitis was lower than that in a healthy control subject. In cultured human colonic epithelial HT-29 cells, pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and IL-1β down-regulate HO-1 expression. The HO-1 inducer, cobalt protoporphyrin IX (CoPPIX), dramatically down-regulated NF-κB activation in HT-29 cells by TNF-α. In addition, bilirubin-a product of heme catabolism by HO-1-and the carbon monoxide donor tricarbonyldichlororuthenium (II) dimer also suppressed NF-κB activation by TNF-α. However, iron, another heme metabolite, did not suppress NF-κB activation by TNF-α. Furthermore, CoPPIX diminished the macroscopic and histopathological symptoms of TNBS-induced colitis and down-regulated NF-κB activation in mice. In conclusion, this study suggests that HO-1 plays an important role in the down-regulation of NF-κB activation, which is a key factor in the pathogenesis of IBD and is thus an excellent therapeutic target for the treatment of IBD.