RESUMO
BACKGROUND & AIMS: Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) in combination with cytopathology is the optimal method for diagnosis and staging of pancreatic ductal adenocarcinoma (PDAC) and other pancreatic lesions. Its clinical utility, however, can be limited by high rates of indeterminate or false-negative results. We aimed to develop and validate a microRNA (miRNA)-based test to improve preoperative detection of PDAC. METHODS: Levels of miRNAs were analyzed in a centralized clinical laboratory by relative quantitative polymerase chain reaction in 95 formalin-fixed paraffin-embedded specimens and 228 samples collected by EUS-FNA during routine evaluations of patients with solid pancreatic masses at 4 institutions in the United States, 1 in Canada, and 1 in Poland. RESULTS: We developed a 5-miRNA expression classifier, consisting of MIR24, MIR130B, MIR135B, MIR148A, and MIR196, that could identify PDAC in well-characterized, formalin-fixed, paraffin-embedded specimens. Detection of PDAC in EUS-FNA samples increased from 78.8% by cytology analysis alone (95% confidence interval, 72.2%-84.5%) to 90.8% when combined with miRNA analysis (95% confidence interval, 85.6%-94.5%). The miRNA classifier correctly identified 22 additional true PDAC cases among 39 samples initially classified as benign, indeterminate, or nondiagnostic by cytology. Cytology and miRNA test results each were associated significantly with PDAC (P < .001), with positive predictive values greater than 99% (95% confidence interval, 96%-100%). CONCLUSIONS: We developed and validated a 5-miRNA classifier that can accurately predict which preoperative pancreatic EUS-FNA specimens contain PDAC. This test might aid in the diagnosis of pancreatic cancer by reducing the number of FNAs without a definitive adenocarcinoma diagnosis, thereby reducing the number of repeat EUS-FNA procedures.
Assuntos
Biópsia por Agulha Fina/métodos , Carcinoma Ductal Pancreático/diagnóstico , Técnicas Citológicas/métodos , Endossonografia/métodos , MicroRNAs/análise , Neoplasias Pancreáticas/diagnóstico , Reação em Cadeia da Polimerase em Tempo Real/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Canadá , Feminino , Humanos , Masculino , MicroRNAs/genética , Pessoa de Meia-Idade , Técnicas de Diagnóstico Molecular/métodos , Polônia , Estudos Prospectivos , Estados Unidos , Adulto JovemRESUMO
OBJECTIVES: Techniques of tissue sampling at endoscopic retrograde cholangiopancreatography (ERCP) have been underutilized due to technical demands, low yield, and lack of immediate intraprocedural diagnosis. The objective of this study was to describe a new inexpensive, highly efficient ERCP tissue processing, and interpretation technique to address these issues. METHODS: A retrospective, institutional review board approved, single-center study was done at a tertiary-care medical center. Between June 2004 and February 2009, 133 patients (age 38-95 years; men 53%) with suspicious biliary strictures underwent ERCP with tissue sampling using a new technique. Small forceps biopsy specimens were forcefully smashed between two dry glass slides, immediately fixed, stained with rapid Papanicolaou, and interpreted by an on-site pathologist during the procedure (Smash protocol). RESULTS: Of the 117 proven to have cancer, true-positive Smash preps included pancreatic cancer 49/66 (74%), cholangiocarcinoma 23/29 (79%), metastatic cancer 8/15 (53%), and other 4/7 (57%). The median number of Smash biopsies to diagnosis was 3 (range 1-17). Suspicious or atypical results were considered to be negative in this study. There were no false positives and no complications. Smash had an overall sensitivity of 89/117 (76%) for all cases. The true-positive yield of immediate Smash prep cytology, combined with ERCP fine needle aspirate (FNA) and forceps biopsy histology was 77/95 (81%) for primary pancreaticobiliary cancers. CONCLUSIONS: Immediate cytopathologic diagnosis at ERCP was established in 72% of patients presenting with suspected malignant biliary obstruction using a new cytological preparation of forceps biopsies. This approach to ERCP tissue sampling permits immediate diagnosis and avoids the need for subsequent procedures, adds little cost and time, and is safe to perform.
Assuntos
Neoplasias dos Ductos Biliares/diagnóstico , Ductos Biliares Intra-Hepáticos , Biópsia/instrumentação , Colangiocarcinoma/diagnóstico , Colangiopancreatografia Retrógrada Endoscópica , Citodiagnóstico/métodos , Neoplasias Pancreáticas/diagnóstico , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias dos Ductos Biliares/patologia , Colangiocarcinoma/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Pancreáticas/patologia , Estudos Retrospectivos , Sensibilidade e EspecificidadeRESUMO
BACKGROUND: Combined liver/small-bowel (L/SB) and multivisceral (MV) transplantation has been increasingly used with significant improvement in outcome. OBJECTIVE: To report our experience with pancreaticobiliary (PB) complications in this unique population. DESIGN AND SETTING: Single-center cohort study using a prospectively completed database. PATIENTS AND INTERVENTIONS: From May 1990 to November 2008, records of 271 consecutive patients who received 289 composite visceral grafts were retrospectively reviewed; 151 of the allografts were L/SB (52%) and the remaining 138 were MV. MAIN OUTCOME MEASUREMENTS: Type, incidence, risk factors, clinical features, and management of PB complications. RESULTS: PB complications were diagnosed in 44 patients with an incidence of 16%. Biliary complications developed in 20 patients (ampullary stenosis in 9, bile duct casts/stones in 6, and bile duct leaks in 5), pancreatic complications occurred in 19 patients (necrotizing pancreatitis in 7, edematous pancreatitis in 6, and pancreatic duct fistulae in 6), and combined biliary and pancreatic complications occurred in 5 patients. The risk of PB complications was significantly higher in MV graft recipients compared with L/SB recipients with a rate of 25% compared with 9%, respectively. ERCP was instrumental in the diagnosis and/or treatment of ampullary stenosis, bile duct casts and stones, bile duct leaks, and recurrent acute pancreatitis. Combined endoscopic and surgical intervention was required in most cases of pancreatic duct fistulae. Surgical intervention was performed in patients with pancreatic allograft necrosis and complex anastomotic biliary leaks. LIMITATIONS: Single-center study. CONCLUSIONS: PB complications are common after composite visceral transplantation. Awareness of these complications is important to the transplantation team to ensure early diagnosis and appropriate intervention in an attempt to minimize morbidity and mortality.
Assuntos
Ampola Hepatopancreática/patologia , Fístula Anastomótica/etiologia , Colangite/etiologia , Doenças do Ducto Colédoco/patologia , Cálculos Biliares/etiologia , Intestino Delgado/transplante , Transplante de Fígado/efeitos adversos , Fístula Pancreática/etiologia , Pancreatite Necrosante Aguda/etiologia , Adolescente , Adulto , Idoso , Criança , Pré-Escolar , Colangiopancreatografia Retrógrada Endoscópica , Doenças do Ducto Colédoco/etiologia , Constrição Patológica/etiologia , Constrição Patológica/patologia , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores de Risco , Taxa de Sobrevida , Adulto JovemRESUMO
OBJECTIVES: Identification of patients at risk for severe disease early in the course of acute pancreatitis (AP) is an important step to guiding management and improving outcomes. A new prognostic scoring system, the bedside index for severity in AP (BISAP), has been proposed as an accurate method for early identification of patients at risk for in-hospital mortality. The aim of this study was to compare BISAP (blood urea nitrogen >25 mg/dl, impaired mental status, systemic inflammatory response syndrome (SIRS), age>60 years, and pleural effusions) with the "traditional" multifactorial scoring systems: Ranson's, Acute Physiology and Chronic Health Examination (APACHE)-II, and computed tomography severity index (CTSI) in predicting severity, pancreatic necrosis (PNec), and mortality in a prospective cohort of patients with AP. METHODS: Extensive demographic, radiographic, and laboratory data from consecutive patients with AP admitted or transferred to our institution was collected between June 2003 and September 2007. The BISAP and APACHE-II scores were calculated using data from the first 24 h from admission. Predictive accuracy of the scoring systems was measured by the area under the receiver-operating curve (AUC). RESULTS: There were 185 patients with AP (mean age 51.7, 51% males), of which 73% underwent contrast-enhanced CT scan. Forty patients developed organ failure and were classified as severe AP (SAP; 22%). Thirty-six developed PNec (19%), and 7 died (mortality 3.8%). The number of patients with a BISAP score of > or =3 was 26; Ranson's > or =3 was 47, APACHE-II > or =8 was 66, and CTSI > or =3 was 59. Of the seven patients that died, one had a BISAP score of 1, two had a score of 2, and four had a score of 3. AUCs for BISAP, Ranson's, APACHE-II, and CTSI in predicting SAP are 0.81 (confidence interval (CI) 0.74-0.87), 0.94 (CI 0.89-0.97), 0.78 (CI 0.71-0.84), and 0.84 (CI 0.76-0.89), respectively. CONCLUSIONS: We confirmed that the BISAP score is an accurate means for risk stratification in patients with AP. Its components are clinically relevant and easy to obtain. The prognostic accuracy of BISAP is similar to those of the other scoring systems. We conclude that simple scoring systems may have reached their maximal utility and novel models are needed to further improve predictive accuracy.
Assuntos
Indicadores Básicos de Saúde , Pancreatite Necrosante Aguda/complicações , Pancreatite Necrosante Aguda/mortalidade , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pancreatite Necrosante Aguda/diagnóstico , Valor Preditivo dos Testes , Prognóstico , Reprodutibilidade dos Testes , Estudos Retrospectivos , Medição de Risco , Adulto JovemRESUMO
Pancreatic lymphoepithelial cysts are rare benign cysts that cannot be reliably differentiated from neoplastic mucinous cysts preoperatively. Although elevated cyst fluid carcinoembryonic antigen (CEA) levels support a diagnosis of a mucinous cyst, the finding of increased CEA levels in lymphoepithelial cysts prompted this study. Nine resected lymphoepithelial cysts were examined for expression of CEA, carbohydrate antigen (CA) 19-9, CK7, p63, PAS-D and a panel of mucins. The pathology data were correlated with clinical information, including serum, cyst fluid and imaging studies. By computed tomography scan, although most lymphoepithelial cysts appeared cystic, 23% were described as masses. The endoscopic ultrasound findings were variable, but the lymphoepithelial cysts tended to be hypoechoic cystic lesions or masses. On cytology, 44% of the cysts had squamous cells, 67% had glandular cells and 56% had atypical cells. The cysts were resected because of size ≥3 cm (89%), symptoms (44%) and/or elevated cyst fluid CEA levels (33%). The cyst fluid CEA levels in the three cysts tested were >450 ng/ml. Histopathologically, all cysts were lined by mature, stratified squamous-type cells and produced keratin. Mucous cells were present in 78% of the cysts. The immunohistochemical profile of the squamous lining was CK7+, p63+, MUC1+, MUC4+, MUC2-, MUC5AC- and MUC6-. Even though lymphoepithelial cysts are lined by squamous-type epithelium, all our resected lymphoepithelial cysts expressed CEA and/or CA19-9, many contained mucous cells, and three exhibited markedly elevated cyst fluid CEA levels. Although cyst fluid CEA levels >200 ng/ml support the diagnosis of mucinous neoplasms, this study emphasizes the need for clinicians and pathologists to recognize that lymphoepithelial cysts can mimic neoplastic mucinous cysts clinically, radiographically and on cyst fluid CEA analysis.
Assuntos
Antígeno Carcinoembrionário/análise , Líquido Cístico/química , Células Epiteliais/química , Tecido Linfoide/química , Mucinas/análise , Neoplasias Císticas, Mucinosas e Serosas/diagnóstico , Cisto Pancreático/diagnóstico , Neoplasias Pancreáticas/diagnóstico , Adulto , Idoso , Biópsia por Agulha Fina , Antígeno CA-19-9/análise , Diagnóstico Diferencial , Endossonografia , Células Epiteliais/patologia , Feminino , Humanos , Imuno-Histoquímica , Queratina-7/análise , Tecido Linfoide/patologia , Masculino , Proteínas de Membrana/análise , Pessoa de Meia-Idade , Neoplasias Císticas, Mucinosas e Serosas/química , Neoplasias Císticas, Mucinosas e Serosas/patologia , Neoplasias Císticas, Mucinosas e Serosas/cirurgia , Cisto Pancreático/química , Cisto Pancreático/patologia , Cisto Pancreático/cirurgia , Neoplasias Pancreáticas/química , Neoplasias Pancreáticas/patologia , Neoplasias Pancreáticas/cirurgia , Pennsylvania , Valor Preditivo dos Testes , Cuidados Pré-Operatórios , Tomografia Computadorizada por Raios XRESUMO
BACKGROUND: Stereotactic body radiotherapy (SBRT) has been approved for the treatment of locally advanced pancreatic cancer. Placement of gold fiducials is required for real-time tracking and delivery of a high-dose therapeutic beam of radiation to the tumor. Traditionally, fiducials have been placed either intraoperatively or percutaneously. Recently, EUS-guided fiducial placement has been reported, but the safety and feasibility of this approach is not well defined. OBJECTIVE: The aim of this study was to determine the safety, feasibility, and limitations of EUS-guided placement of 0.8 x 5.0 mm fiducials via a 19-gauge needle for locally advanced and recurrent pancreatic cancer. DESIGN: Prospective study of patients with either locally advanced or recurrent pancreatic cancer referred for EUS-guided fiducial placement for SBRT at our institution over a 3-year period. SETTING: Tertiary referral center conducting >1800 EUS procedures annually. MAIN OUTCOME MEASUREMENTS: Primary outcome measurements included success, complications, and technical limitations of EUS-guided fiducial placement in pancreatic cancer. In addition, the percentage of patients successfully completing SBRT after EUS-guided fiducial placement was determined. RESULTS: A total of 51 patients (mean age 73 years; 57% male) with locally advanced (n = 36) and recurrent (n = 15) pancreatic cancer were referred for EUS-guided fiducial placement. Fiducials were successfully placed in 46 patients (90%), with technical failures occurring in 4 patients (8%) with recurrent cancer after pancreaticoduodenectomy. In 3 patients (7%), the fiducials spontaneously migrated from the original site of injection, thereby requiring a second EUS procedure for placement of additional fiducials. Of the 46 patients with fiducials placed under EUS guidance, 42 patients (91%) successfully completed SBRT. Two patients experienced disease progression before SBRT, 1 patient was lost to follow-up, and 1 patient experienced a complication at ERCP that precluded further therapy. Only 1 complication (2%), of mild pancreatitis, occurred in a patient undergoing simultaneous placement of fiducials and celiac plexus neurolysis for intractable abdominal pain. LIMITATIONS: Single-center experience and lack of a formal follow-up protocol to assess for complications. CONCLUSION: EUS-guided fiducial placement for SBRT in locally advanced and recurrent pancreatic cancer is safe and feasible. Successful placement was achieved in 90% of patients, with a low complication rate (2%). Furthermore, 91% of patients successfully completed SBRT after EUS-guided fiducial delivery. Although fiducials can spontaneously migrate from the initial injection site, the rate of migration is relatively low (7%), and no migration-related complications occurred over the course of this study. Limitations to EUS-guided fiducial placement may include surgically altered anatomy (pancreaticoduodenectomy) in patients with recurrent pancreatic cancer.
Assuntos
Endossonografia/métodos , Agulhas , Recidiva Local de Neoplasia/cirurgia , Neoplasias Pancreáticas/cirurgia , Radiocirurgia/instrumentação , Idoso , Progressão da Doença , Desenho de Equipamento , Feminino , Seguimentos , Humanos , Imageamento por Ressonância Magnética , Masculino , Recidiva Local de Neoplasia/diagnóstico por imagem , Neoplasias Pancreáticas/diagnóstico por imagem , Estudos Prospectivos , Reprodutibilidade dos Testes , Tomografia Computadorizada por Raios X , Resultado do TratamentoRESUMO
BACKGROUND: The Wallstent has remained the industry standard for biliary self-expanding metal stents (SEMSs). Recently, stents of differing designs, compositions, and diameters have been developed. OBJECTIVE: To compare the new nitinol 6-mm and 10-mm Zilver stents with the 10-mm stainless steel Wallstent and determine the mechanism of obstruction. DESIGN: Randomized, prospective, controlled study. SETTING: Nine centers experienced in SEMS placement during ERCP. PATIENTS: A total of 241 patients presenting between September 2003 and December 2005 with unresectable malignant biliary strictures at least 2 cm distal to the bifurcation. MAIN OUTCOME MEASUREMENT: Stent occlusions requiring reintervention and death. RESULTS: At interim analysis, a significant increase in occlusions was noted in the 6-mm Zilver group at the P = .04 level, resulting in arm closure but continued follow-up. Final study arms were 64, 88, and 89 patients receiving a 6-mm Zilver, 10-mm Zilver, and 10-mm Wallstent, respectively. Stent occlusions occurred in 25 (39.1%) of the patients in the 6-mm Zilver arm, 21 (23.9%) of the patients in the 10-mm Zilver arm, and 19 (21.4%) of the patients in the 10-mm Wallstent arm (P = .02). The mean number of days of stent patency were 142.9, 185.8, and 186.7, respectively (P = .057). No differences were noted in secondary endpoints, and the study was ended at the 95% censored study endpoints. Biopsy specimens of ingrowth occlusive tissue revealed that 56% were caused by benign epithelial hyperplasia. CONCLUSIONS: SEMS occlusions were much more frequent with a 6-mm diameter SEMS and equivalent in the two 10-mm arms despite major differences in stent design, material, and expansion, suggesting that diameter is the critical feature. Malignant tumor ingrowth produced only a minority of the documented occlusions.
Assuntos
Cateterismo/métodos , Colestase/patologia , Colestase/terapia , Cuidados Paliativos/métodos , Stents , Adulto , Idoso , Idoso de 80 Anos ou mais , Ligas , Neoplasias dos Ductos Biliares/complicações , Neoplasias dos Ductos Biliares/patologia , Colangiopancreatografia Retrógrada Endoscópica/métodos , Colestase/etiologia , Colestase/mortalidade , Feminino , Humanos , Cooperação Internacional , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Seleção de Pacientes , Probabilidade , Prognóstico , Estudos Prospectivos , Desenho de Prótese , Falha de Prótese , Qualidade de Vida , Medição de Risco , Aço Inoxidável , Análise de Sobrevida , Doente Terminal , Resultado do TratamentoRESUMO
BACKGROUND: The surgeon's contribution to patients with localized pancreatic adenocarcinoma (PAC) is a margin negative (R0) resection. We hypothesized that a prediction rule based on pre-operative imaging would maximize the R0 resection rate while reducing non-therapeutic intervention. METHODS: The prediction rule was developed using computed tomography (CT) and endoscopic ultrasound (EUS) data from 65 patients with biopsy-proven PAC who underwent attempted resection. The rule classified patients as low or high risk for non-R0 outcome and was validated in 78 subsequent patients. RESULTS: MODEL VARIABLES WERE: any evidence of vascular involvement on CT; EUS stage and EUS size dichotomized at 2.6 cm. In the validation cohort, 77% underwent resection and 58% achieved R0 status. If only patients in the low-risk group underwent surgery, the prediction rule would have increased the resection rate to 92% and the R0 rate to 73%. The R0 rate was 40% higher in low-risk compared with high-risk patients (P < 0.001). High risk was associated with a 67% rate of non-curative surgery (unresectable disease and metastases). CONCLUSION: The prediction rule identified patients most likely to benefit from resection for PAC using pre-operative CT and EUS findings. Model predictions would have increased the R0 rate and reduced non-therapeutic interventions.
Assuntos
Endossonografia , Pâncreas/anormalidades , Fístula Pancreática/cirurgia , Pancreatite Crônica/cirurgia , Doenças Pleurais/cirurgia , Fístula do Sistema Respiratório/cirurgia , Stents , Idoso , Colangiopancreatografia Retrógrada Endoscópica , Humanos , Masculino , Fístula Pancreática/diagnósticoRESUMO
Since the initial report 20 years ago by Marshall and Warren of an unidentified curved bacillus located on the gastric epithelium of patients with chronic active gastritis, the discovery of Helicobacter pylori and its association with a number of gastrointestinal diseases has revolutionized the field of gastroenterology. Although the association of H. pylori infection with peptic ulcer disease, chronic gastritis, mucosa-associated lymphoid tissue lymphoma, and gastric adenocarcinoma has been well documented over the past two decades, other areas remain less clear, including the role of H. pylori in gastropathy associated with nonsteroidal anti-inflammatory drugs, gastroesophageal reflux disease, and both uninvestigated and nonulcer dyspepsia. Although these areas still remain somewhat controversial, recent reports further clarify the role of H. pylori in these conditions. A review of the recent literature regarding H. pylori-associated diseases is presented along with recommendations for diagnosis and treatment of H. pylori infection.
Assuntos
Refluxo Gastroesofágico/microbiologia , Infecções por Helicobacter/complicações , Helicobacter pylori , Úlcera Péptica/etiologia , Adenocarcinoma/tratamento farmacológico , Adenocarcinoma/microbiologia , Animais , Anti-Inflamatórios não Esteroides/efeitos adversos , Anti-Inflamatórios não Esteroides/uso terapêutico , Dispepsia/tratamento farmacológico , Dispepsia/etiologia , Refluxo Gastroesofágico/tratamento farmacológico , Neoplasias Gastrointestinais/tratamento farmacológico , Neoplasias Gastrointestinais/genética , Neoplasias Gastrointestinais/microbiologia , Infecções por Helicobacter/diagnóstico , Infecções por Helicobacter/tratamento farmacológico , Humanos , Linfoma de Zona Marginal Tipo Células B/tratamento farmacológico , Linfoma de Zona Marginal Tipo Células B/genética , Linfoma de Zona Marginal Tipo Células B/microbiologia , Úlcera Péptica/tratamento farmacológico , Úlcera Péptica/microbiologiaRESUMO
Hepatopulmonary syndrome, arterial hypoxemia caused by intrapulmonary vasodilatation, occurs in approximately 10% of patients with cirrhosis. The severity of hypoxemia affects liver transplant candidacy and is associated with increased morbidity and mortality posttransplantation. Screening guidelines for detecting the presence of arterial hypoxemia do not exist. The aim of this study is to investigate the accuracy and utility of pulse oximetry in the detection of hypoxemia (PaO(2) < 70 mm Hg) in patients with cirrhosis. Two hundred prospective liver transplant candidates were compared with 94 controls. Arterial oxyhemoglobin saturation was obtained by pulse oximetry (SpO(2)) and compared with simultaneous arterial blood gas (ABG) oxyhemoglobin values (SaO(2); bias = the difference). PaO(2), carboxyhemoglobin, methemoglobin, and routine clinical and biochemical parameters were investigated to account for the bias. SpO(2) overestimated SaO(2) in 98% of patients with cirrhosis (mean bias, 3.37%; range, -1% to 10%). Forty-four percent of patients with cirrhosis and controls had a bias of 4% or greater. No clinical or biochemical parameters of cirrhosis accounted for the overestimation of pulse oximetry. Twenty-five subjects with cirrhosis were hypoxemic, and an SpO(2) of 97% or less showed a sensitivity of 96% and a positive likelihood ratio of 3.9 for detecting hypoxemia. An SpO(2) of 94% or less detected all subjects with an arterial PaO(2) less than 60 mm Hg. Pulse oximetry significantly overestimates arterial oxygenation, and the inaccuracy is not influenced by liver disease. Nevertheless, pulse oximetry can be a useful screening tool to detect arterial hypoxemia in patients with cirrhosis, but a higher threshold for obtaining an ABG must be used.
Assuntos
Hipóxia/complicações , Cirrose Hepática/complicações , Cirrose Hepática/cirurgia , Transplante de Fígado/fisiologia , Oximetria , Adulto , Idoso , Bilirrubina/sangue , Carboxihemoglobina/análise , Feminino , Humanos , Hipóxia/sangue , Hipóxia/diagnóstico , Masculino , Metemoglobina/análise , Pessoa de Meia-Idade , Oxigênio/sangue , Oxiemoglobinas/análise , Análise de Regressão , Reprodutibilidade dos Testes , Resultado do TratamentoRESUMO
Toll-like receptor 4 (TLR4) has been identified as a transmembrane protein involved in the host innate immune response to gram-negative bacterial lipopolysaccharide (LPS). Upon activation by LPS recognition, the TIR domain of TLR4 signals through MyD88 to activate the nuclear factor kappa B (NF-kappa B) pathway, a critical regulator of many proinflammatory genes, including interleukin-8 (IL-8). Emerging evidence suggests that reactive oxygen species (ROS) can contribute to diverse signaling pathways, including the LPS-induced cascade. In the present study we investigated the role of ROS in TLR-mediated signaling. Purified Escherichia coli LPS, a highly specific TLR4 agonist, elicited an oxidative burst in the monocyte-like cell line THP-1 in a time- and dose-dependent manner. This oxidative burst was shown to be dependent on the presence of TLR4 through transfection studies in HEK cells, which do not normally express this protein, and with bone marrow-derived macrophages from C3H/HeJ mice, which express a mutated TLR4 protein. LPS-stimulated IL-8 expression could be blocked by the antioxidants N-acetyl-L-cysteine and dimethyl sulfoxide at both the protein and mRNA levels. These antioxidants also blocked LPS-induced IL-8 promoter transactivation as well as the nuclear translocation of NF-kappa B. These data provide evidence that ROS regulate immune signaling through TLR4 via their effects on NF-kappa B activation.