Identification of SAMD9L as a susceptibility locus for intravenous immunoglobulin resistance in Kawasaki disease by genome-wide association analysis.

Kawasaki disease (KD) is a systemic vasculitis affecting infants and children; it manifests as fever and signs of mucocutaneous inflammation. Intravenous immunoglobulin (IVIG) treatment effectively attenuates the fever and systemic inflammation. However, 10-20% patients are unresponsive to IVIG. To identify genetic variants influencing IVIG non-response in KD, a genome-wide association study (GWAS) and a replication study were performed using a total of 148 IVIG non-responders and 845 IVIG-responders in a Korean population. rs28662 in the sterile alpha motif domain-containing protein 9-like (SAMD9L) locus showed the most significant result in the joint analysis of GWAS and replication samples (odds ratio (OR) = 3.47, P = 1.39 × 10-5). The same SNP in the SAMD9L locus was tested in the Japanese population, and it revealed a more significant association in a meta-analysis with Japanese data (OR = 4.30, P = 5.30 × 10-6). These results provide new insights into the mechanism of IVIG response in KD.

Identification of the TIFAB Gene as a Susceptibility Locus for Coronary Artery Aneurysm in Patients with Kawasaki Disease.

Kawasaki disease (KD) is a self-limiting systemic vasculitis of unknown etiology. KD is often complicated by coronary artery aneurysms (CAAs), which develop in about 20-25% of untreated children and 3-5% of children treated with intravenous immunoglobulin therapy. To identify the risk loci for CAA susceptibility in patients with KD, we performed a genome-wide association study (GWAS) using our previous Illumina HumanOmni1-Quad BeadChip data (296 KD patients) and a new replication study in an independent sample set (713 KD patients) by grouping KD patients without CAA (control) versus KD patients with extremely large aneurysms (diameter ≥ 5 mm) (case). Among 44 candidate single -nucleotide polymorphisms (SNPs) selected from the initial GWAS data (33 cases vs. 215 controls), a SNP (rs899162) located 7 kb upstream of the TIFAB gene on chromosome five was replicated in an independent sample (12 cases vs. 532 controls). In the combined analysis (45 cases vs. 747 controls), the SNP (rs899162) showed a highly significant association with CAA formation (diameter ≥ 5 mm) in patients with KD (odds ratio = 3.20, 95% confidence interval = 2.02-5.05, Pcombined = 1.95 × 10-7). These results indicate that the TIFAB gene may act as a CAA susceptibility locus in patients with KD.

A genome-wide association analysis identifies NMNAT2 and HCP5 as susceptibility loci for Kawasaki disease.

Kawasaki disease (KD), a systemic vasculitis of infants and children, manifests as fever and mucocutaneous inflammation. Although its etiology is largely unknown, the epidemiological data suggest that genetic factors are important in KD susceptibility. To identify genetic variants influencing KD susceptibility, we performed a genome-wide association study (GWAS) and replication study using a total of 915 children with KD and 4553 controls in the Korean population. Six single-nucleotide polymorphisms (SNPs) in three loci were associated significantly with KD susceptibility (P<1.0 × 10-5), including the previously reported BLK locus (rs6993775, odds ratio (OR)=1.52, P=2.52 × 10-11). The other two loci were newly identified: NMNAT2 on chromosome 1q25.3 (rs2078087, OR=1.33, P=1.15 × 10-6) and the human leukocyte antigen (HLA) region on chromosome 6p21.3 (HLA-C, HLA-B, MICA and HCP5) (rs9380242, rs9378199, rs9266669 and rs6938467; OR=1.33-1.51, P=8.93 × 10-6 to 5.24 × 10-8). Additionally, SNP rs17280682 in NLRP14 was associated significantly with KD with a family history (18 cases vs 4553 controls, OR=6.76, P=5.46 × 10-6). These results provide new insights into the pathogenesis and pathophysiology of KD.

Assessment of risk factors for Korean children with Kawasaki disease.

Kawasaki disease (KD) is the most common cause of acquired heart disease in children. Intravenous immunoglobulin (IVIG) is the standard therapy for KD, but more than 10% of KD patients do not respond to IVIG and are at high risk for the development of coronary artery lesions (CALs). To identify clinical and genetic risk factors associated with CAL development and IVIG nonresponsiveness, this study analyzed the clinical data for 478 Korean KD patients. Multivariate logistic regression analysis showed that incomplete KD, IVIG nonresponse, fever duration of 7 days or longer, and the CC/AC genotypes of the rs7604693 single nucleotide polymorphism (SNP) in the PELI1 gene were significantly associated with the development of CALs, with odds ratios (ORs) ranging from 2.06 to 3.04. The risk of CAL formation was synergistically increased by the addition of individual risk factors, particularly the genetic variant in the PELI1 gene. Multivariate analysis also showed that a serum albumin level of 3.6 g/dl or lower was significantly associated with nonresponsiveness to IVIG [OR, 2.76; 95% confidence interval (CI), 1.34-5.68; P = 0.006]. Conclusively, incomplete KD, IVIG nonresponsiveness, long febrile days, and the rs7604693 genetic variant in the PELI1 gene are major risk factors for the development of CALs, whereas low serum albumin concentration is an independent risk factor for IVIG nonresponsiveness.

Idiopathic cardiomyopathies in Korean children. - 9-Year Korean Multicenter Study-.

BACKGROUND: Idiopathic cardiomyopathies (CMPs) are an important heterogeneous group of diseases. With the advance of therapeutic strategies, epidemiologic data on CMP have become very important, but only a few have been reported in Asian children. We conducted a retrospective epidemiologic study of primary CMP in Korean children. METHODS AND RESULTS: Using a multicenter survey, we studied primary CMP among Korean children from January 1998 to December 2006 based on classification (2006) of CMP by the American Heart Association. A total of 277 primary CMP patients were reported from 17 cardiovascular centers. The average annual occurrence of new cases of primary CMP was 0.28 per 100,000 Korean children younger than 15 years of age (95% confidence interval (CI) 0.24-0.31). Dilated CMP (DCMP) was 66.43%, hypertrophic CMP (HCMP) 23.47%, restrictive CMP (RCMP) 6.50% and others 3.61%. The point prevalence of primary CMP at the end of the study was estimated as 2.11/100,000 (95%CI 1.83-2.43), DCMP 1.39/100,000, HCMP 0.51/100,000, RCMP 0.16/100,000 and others 0.04/100,000. Survival rates over 9 years were 69.8% in DCMP, 90.3% in HCMP, and 47.2% in RCMP. CONCLUSIONS: Recent point prevalence of childhood primary CMP in Korea was estimated as 2.11/100,000. Further epidemiologic study with a nationwide survey is necessary.

Clinical characteristics of hemophagocytic lymphohistiocytosis related to Kawasaki disease.

It is difficult to predict the prognosis or clinical course of secondary hemophagocytic lymphohistiocytosis (HLH) due to the various underlying causes. The authors analyzed the clinical and laboratory findings and outcomes in patients with HLH who had initially been diagnosed with Kawasaki disease (KD), and evaluated the clinical significance of each factor. Among the 21 patients with HLH, 5 had initially been diagnosed with KD and 16 had other etiologies. A comparative analysis was performed for fever duration, presence of cytopenia, serum ferritin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), triglyceride, fibrinogen, hyponatremia, reactivation, and survival rate in those HLH patients associated with KD (group I) and other causes (group II). In patients in group I, a higher level of reactivation (20%), a lower survival rate (P = .001), higher AST (P = .031) and ferritin (P = .005), and frequent hyponatremia (P = .000) were found compared to patients in group II. Interestingly, patients in group I was older than the average of age of most KD patients. A high index of suspicion on the progression from KD to HLH would be mandatory when the KD patients show elevated AST and ferritin and the presence of hyponatremia, and especially so if the patient is of older age.

Infliximab Treatment for Intravenous Immunoglobulin-resistant Kawasaki Disease: a Multicenter Study in Korea.

BACKGROUND AND OBJECTIVES: We investigated the status of infliximab use in intravenous immunoglobulin (IVIG)-resistant Kawasaki disease (KD) patients and the incidence of coronary artery aneurysms (CAAs) according to treatment regimens. METHODS: Between March 2010 and February 2017, 16 hospitals participated in this study. A total of 102 (32.3±19.9 months, 72 males) who received infliximab at any time after first IVIG treatment failure were enrolled. Data were retrospectively collected using a questionnaire. RESULTS: Subjects were divided into two groups according to the timing of infliximab administration. Early treatment (group 1) had shorter fever duration (10.5±4.4 days) until infliximab infusion than that in late treatment (group 2) (16.4±4.5 days; p<0.001). We investigated the response rate to infliximab and the incidence of significant CAA (z-score >5). Overall response rate to infliximab was 89/102 (87.3%) and the incidence of significant CAA was lower in group 1 than in group 2 (1/42 [2.4%] vs. 17/60 [28.3%], p<0.001). CONCLUSIONS: This study suggests that the early administration of infliximab may reduce the incidence of significant CAA in patients with IVIG-resistant KD. However, further prospective randomized studies with larger sample sizes are required.

Assessment of the Clinical Heterogeneity of Kawasaki Disease Using Genetic Variants of BLK and FCGR2A.

BACKGROUND AND OBJECTIVES: Patients with Kawasaki disease (KD) are clinically heterogeneous because its diagnosis is based solely on clinical observation and there are no definitive biomarkers. We dissected the clinical heterogeneity of KD patients using the KD-associated genetic variants. METHODS: We performed a genetic association analysis in several KD subgroups categorized by clinical characteristics using the KD-associated variants of the B lymphoid tyrosine kinase (BLK; rs6993775) and Fc gamma receptor II a (FCGR2A; rs1801274) in a large number of case (n=1,011) and control (n=4,533) samples. RESULTS: BLK and FCGR2A were very significantly associated with KD in Korean KD patients (odds ratio [OR],1.48; p=4.63×10⁻¹¹ for BLK, and OR, 1.26; p=1.42×10⁻4 for FCGR2A). However, in KD subgroup analysis, we found that neither BLK nor FCGR2A were associated with either incomplete Kawasaki disease (iKD) type patients or those older than 5 years of age (p>0.2), suggesting that patients with iKD or those older than 5 years of age are a unique subgroup of KD. In genetic association analysis after excluding iKD patients and those older than 5 years old, we found that BLK was associated with all KD subgroups, whereas FCGR2A was specifically associated with male KD patients younger than 1 year of age (OR, 2.22; p=2.35×10⁻5). CONCLUSIONS: KD is a clinically and genetically heterogeneous disease. These findings will provide new insights into the clinical and genetic heterogeneity of KD.

C-reactive protein and N-terminal pro-brain natriuretic peptide discrepancy: a differentiation of adenoviral pharyngoconjunctival fever from Kawasaki disease.

PURPOSE: To differentiate adenoviral pharyngoconjunctival fever (PCF) from acute Kawasaki disease (KD) using laboratory tests before results of virus-real time polymerase chain reaction and ophthalmologic examination are obtained. METHODS: Baseline patient characteristics and laboratory measurements were compared between 40 patients with adenovirus infection and 123 patients with KD. RESULTS: The patients with adenovirus infection were generally older than those with KD (median: 3.9 years vs. 2 years, P=0.000). White blood cell and, platelet count, and aspartate aminotransferase, alanine aminotransferase, and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels showed significant differences between the 2 groups, but the C-reactive protein (CRP) levels did not (6.8±3.0 mg/dL vs. 8.3±5.8 mg/dL, P=0.126). In the adenovirus infection group, the CRP levels were <1, <3, <10, and ≥10 mg/dL in 2 (5%), 3 (7.5%), 30 (75%), and 5 patients (12.5%), respectively. The cutoff NT-proBNP level was 265 pg/mL. Discrepancy was defined as CRP and NT-proBNP levels of ≥3 or <3 mg/dL, and <265 or ≥265 pg/mL, respectively. Among the 35 patients with adenovirus infection whose CRP levels were ≥3 mg/dL, 29 (82.9%) showed a discrepancy. Conversely, of the 103 patients with KD whose CRP levels were ≥3 mg/dL, 83 (80.6%) showed no discrepancy. Between the groups, a significant difference in discrepancy rate was observed (P=0.000). None of the patients with adenovirus infection had CRP and NT-proBNP levels of <3 mg/dL and ≥265 pg/mL, respectively. CONCLUSION: With a sensitivity of 82.9% and a specificity of 80.6%, CRP and NT-proBNP levels may differentiate between adenoviral PCF and acute KD.

Differentiation between incomplete Kawasaki disease and secondary hemophagocytic lymphohistiocytosis following Kawasaki disease using N-terminal pro-brain natriuretic peptide.

PURPOSE: Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome with many causes, including Kawasaki disease (KD). The purpose of this study was to identify the laboratory tests needed to easily differentiate KD with HLH from incomplete KD alone. METHODS: We performed a retrospective study on patients diagnosed with incomplete KD and incomplete KD with HLH (HLH-KD) between January 2012 and March 2015. We compared 8 secondary HLH patients who were first diagnosed with incomplete KD with all 247 incomplete KD diagnosed patients during the study period. The complete blood count, erythrocyte sedimentation rate, platelet count, and serum total protein, albumin, triglyceride, C-reactive protein, N-terminal pro-brain natriuretic peptide (NT-proBNP), and ferritin levels were compared. Clinical characteristics and echocardiography findings were also compared between the 2 groups. RESULTS: The total duration of fever was longer in the HLH-KD group than in the KD group. White blood cell and platelet counts were higher in the KD group. Alanine aminotransferase, ferritin, and coronary artery diameter were increased in the HLH-KD group compared with those in the KD group. The median of NT-proBNP was significantly higher in the HLH-KD group than in the KD group at 889.0 (interquartile range [IQR], 384.5-1792.0) pg/mL vs. 233.0 (IQR, 107.0-544.0) pg/mL. CONCLUSION: The NT-proBNP level may be helpful in distinguishing incomplete KD from KD with HLH. The NT-proBNP level should be determined in KD patients with prolonged fever, in addition to the white blood cell count, platelet count, and ferritin level, to evaluate secondary HLH.

Identification of LEF1 as a Susceptibility Locus for Kawasaki Disease in Patients Younger than 6 Months of Age.

Kawasaki disease (KD) is an acute febrile vasculitis predominately affecting infants and children. The dominant incidence age of KD is from 6 months to 5 years of age, and the incidence is unusual in those younger than 6 months and older than 5 years of age. We tried to identify genetic variants specifically associated with KD in patients younger than 6 months or older than 5 years of age. We performed an age-stratified genome-wide association study using the Illumina HumanOmni1-Quad BeadChip data (296 cases vs. 1,000 controls) and a replication study (1,360 cases vs. 3,553 controls) in the Korean population. Among 26 candidate single nucleotide polymorphisms (SNPs) tested in replication study, only a rare nonsynonymous SNP (rs4365796: c.1106C＞T, p.Thr369Met) in the lymphoid enhancer binding factor 1 (LEF1) gene was very significantly associated with KD in patients younger than 6 months of age (odds ratio [OR], 3.07; pcombined = 1.10 × 10-5), whereas no association of the same SNP was observed in any other age group of KD patients. The same SNP (rs4365796) in the LEF1 gene showed the same direction of risk effect in Japanese KD patients younger than 6 months of age, although the effect was not statistically significant (OR, 1.42; p = 0.397). This result indicates that the LEF1 gene may play an important role as a susceptibility gene specifically affecting KD patients younger than 6 months of age.

Male-specific association of the FCGR2A His167Arg polymorphism with Kawasaki disease.

Kawasaki disease (KD) is an acute systemic vasculitis that can potentially cause coronary artery aneurysms in some children. KD occurs approximately 1.5 times more frequently in males than in females. To identify sex-specific genetic variants that are involved in KD pathogenesis in children, we performed a sex-stratified genome-wide association study (GWAS), using the Illumina HumanOmni1-Quad BeadChip data (249 cases and 1,000 controls) and a replication study for the 34 sex-specific candidate SNPs in an independent sample set (671 cases and 3,553 controls). Male-specific associations were detected in three common variants: rs1801274 in FCGR2A [odds ratio (OR) = 1.40, P = 9.31 × 10-5], rs12516652 in SEMA6A (OR = 1.87, P = 3.12 × 10-4), and rs5771303 near IL17REL (OR = 1.57, P = 2.53 × 10-5). The male-specific association of FCGR2A, but not SEMA6A and IL17REL, was also replicated in a Japanese population (OR = 1.74, P = 1.04 × 10-4 in males vs. OR = 1.22, P = 0.191 in females). In a meta-analysis with 1,461 cases and 5,302 controls, a very strong association of KD with the nonsynonymous SNP rs1801274 (p.His167Arg, previously assigned as p.His131Arg) in FCGR2A was confirmed in males (OR = 1.48, P = 1.43 × 10-7), but not in the females (OR = 1.17, P = 0.055). The present study demonstrates that p.His167Arg, a KD-associated FCGR2A variant, acts as a susceptibility gene in males only. Overall, the gender differences associated with FCGR2A in KD provide a new insight into KD susceptibility.

Infliximab as the First Retreatment in Patients with Kawasaki Disease Resistant to Initial Intravenous Immunoglobulin.

Forty-three patients with Kawasaki disease who were resistant to initial intravenous immunoglobulin (IVIG) were randomized to receive either a second dose of IVIG (n = 32) or an infliximab (n = 11). With IVIG retreatment 21 patients (65.6%) responded, and with infliximab 10 patients (90.9%) responded. The infliximab group had shorter duration of fever and fewer days of hospitalization. Coronary artery outcomes and adverse events were similar.

Uveitis as an important ocular sign to help early diagnosis in Kawasaki disease.

PURPOSE: Incomplete Kawasaki disease (KD) is frequently associated with delayed diagnosis and treatment. Delayed diagnosis leads to increasing risk of coronary artery aneurysm. Anterior uveitis is an important ocular sign of KD. The purpose of this study was to assess differences in laboratory findings, including echocardiographic measurements, clinical characteristics such as fever duration and treatment responses between KD patients with and those without uveitis. METHODS: We conducted a prospective study with 110 KD patients from January 2008 to June 2013. The study group (n=32, KD with uveitis) was compared with the control group (n=78, KD without uveitis). Laboratory data were obtained from each patient including complete blood count (CBC), erythrocyte sedimentation rate (ESR), platelet count, and level of alanine aminotransferase, aspartate aminotransferase, serum total protein, albumin, C-reactive protein (CRP), and N-terminal probrain natriuretic peptide (NT-pro BNP). Echocardiographic measurements and intravenous immunoglobulin responses were compared between the two groups. RESULTS: The incidence of uveitis was 29.0%. Neutrophil counts and patient age were higher in the uveitis group than in the control group. ESR and CRP level were slightly increased in the uveitis group compared with the control group, but the difference between the two groups was not significant. No significant differences in coronary arterial complication and treatment responses were observed between the two groups. CONCLUSION: Uveitis is an important ocular sign in the diagnosis of incomplete KD. It is significantly associated with patient age and neutrophil count.

Cardiovascular screening in asymptomatic adolescents with metabolic syndrome.

BACKGROUND: In recent days, the prevalence of childhood metabolic syndrome (MS) has increased substantially due to the increasing rate of childhood obesity on a global scale. The aims of this study were to detect the important parameters and provide the screening system to prevent cardiovascular disease in adolescents with MS. METHODS: Ninety one male adolescents were divided into two groups based on the presence or absence of MS. Anthropometric measurement and laboratory study were studied. Intimal medial thickness and pulse wave velocity were estimated. Left ventricular mass index (LVMI), ejection fraction, myocardial velocity, strain and strain rate were measured by tissue Doppler imaging and strain rate imaging. RESULTS: The prevalence of MS was 7.7%. Weight, body mass index (BMI), waist circumference (WC), glucose, insulin, homeostasis model assessment of insulin resistance, triglyceride and LVMI were significantly increased in the MS group. High density lipoprotein-cholesterol (HDL-C), peak early diastolic myocardial velocity (e'), systolic myocardial velocity (s') and global longitudinal strain were significantly lower in the MS group. In univariant analysis, LVMI was significantly correlated with BMI, WC, fat %, fat mass, systolic blood pressure, alanine aminotransferase, total cholesterol (TC) and low density lipoprotein-cholesterol. e' was significantly correlated with BMI, fat %, fat mass, and HDL-C. Global circumferential strain had significant correlation with glucose and TC. Basal anterolateral strain rate was significantly correlated with weight, BMI, WC, fat %, and fat mass. CONCLUSION: LVMI, strain and strain rate are practical and accurate parameters for assessment of left ventricular function in adolescents with MS.

Fulminant myocarditis successfully treated with high-dose immunoglobulin.

Fulminant myocarditis is characterized by the rapid development of life-threatening congestive heart failure. Intravenous immunoglobulin (IVIG), by modulating the immune response, may be used for the treatment of acute myocarditis. We report two children with fulminant myocarditis successfully treated with a 10-h infusion of high-dose IVIG. In those cases, a dramatic clinical improvement was achieved, with both cardiac enzymes and myocardial function normalized within 1-2 weeks after treatment.

Clinical characteristics and serum N-terminal pro-brain natriuretic peptide as a diagnostic marker of Kawasaki disease in infants younger than 3 months of age.

PURPOSE: The incidence of Kawasaki disease (KD) is rare in young infants (less than 3 months of age), who present with only a few symptoms that fulfill the clinical diagnostic criteria. The diagnosis for KD can therefore be delayed, leading to a high risk of cardiac complications. We examined the clinical characteristics and measured the serum levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) levels of these patients for assessing its value in the early detection of KD. METHODS: We retrospectively reviewed the data of young infants diagnosed with KD from 2004 to 2012. The control group included 20 hospitalized febrile patients. Laboratory data, including NT-proBNP were obtained for each patient in both groups. RESULTS: Incomplete KD was observed in 21/24 patients (87.5%). The mean fever duration on admission was 1.36±1.0 days in the KD group. Common symptoms included erythema at the site of Bacille Calmette-Guerin inoculation (70.8%), skin rash (50.0%), changes of oropharyngeal mucosa (29.1%), and cervical lymphadenopathy (20.8%). The mean number of major diagnostic criteria fulfilled was 2.8±1.4. Five KD patients (20.8%) had only one symptom matching these criteria. The incidence of coronary artery complications was 12.5%. The mean serum NT-proBNP level in the acute phase, in the KD and control groups, were 4,159±3,714 pg/mL and 957±902 pg/mL, respectively, which decreased significantly in the convalescent phase. CONCLUSION: Incomplete KD was observed in 87.5% patients. Serum NT-proBNP might be a valuable biomarker for the early detection of KD in febrile infants aged <3 months.

Is high-dose aspirin necessary in the acute phase of kawasaki disease?

BACKGROUND AND OBJECTIVES: We sought to determine whether high-dose aspirin is necessary for the acute therapy of Kawasaki disease (KD) in the intravenous immunoglobulin (IVIG) era. SUBJECTS AND METHODS: Two groups of KD patients treated during the different periods were included. Study group (n=51, treated with IVIG without concomitant use of aspirin in the acute phase) was compared with control group (n=129, treated with IVIG plus high-dose aspirin) with regard to the response to IVIG, duration of fever after IVIG completion, time to C-reactive protein (CRP) <3 mg/dL, and the incidence of coronary artery lesions (CALs). RESULTS: There was no difference between the groups in age, sex, and duration of fever before treatment. Pre-IVIG laboratory measures also did not differ from each other. IVIG-resistant cases were 8 (15.7%) in study group and 22 (17.1%) in control group (p=1.000). Mean duration of fever after IVIG completion in IVIG-responsive patients was 13.3±13.5 hours in study group compared to 6.2±8.3 hours in control group (p=0.000). The mean time to decrease in CRP was 4.0±1.7 days in study group and 4.1±2.2 days in control group (p=0.828). There were 2 (3.9%) patients with CALs in study group and 10 (7.8%) in control group (p=0.514). CONCLUSION: Although high-dose aspirin shortens the duration of fever, treatment without aspirin in the acute phase has no influence on the response to IVIG, resolution of inflammation, or the development of CALs. In the IVIG era, high-dose aspirin may provide little benefit to the treatment in the acute phase of KD.

An inhibitory effect of tumor necrosis factor-alpha antagonist to gene expression in monocrotaline-induced pulmonary hypertensive rats model.

PURPOSE: Tumor necrosis factor (TNF)-α is thought to contribute to pulmonary hypertension. We aimed to investigate the effect of infliximab (TNF-α antagonist) treatment on pathologic findings and gene expression in a monocrotaline-induced pulmonary hypertension rat model. METHODS: Six-week-old male Sprague-Dawley rats were allocated to 3 groups: control (C), single subcutaneous injection of normal saline (0.1 mL/kg); monocrotaline (M), single subcutaneous injection of monocrotaline (60 mg/kg); and monocrotaline + infliximab (M+I), single subcutaneous injection of monocrotaline plus single subcutaneous injection of infliximab (5 mg/kg). The rats were sacrificed after 1, 5, 7, 14, or 28 days. We examined changes in pathology and gene expression levels of TNF-α, endothelin-1 (ET-1), endothelin receptor A (ERA), endothelial nitric oxide synthase (eNOS), matrix metalloproteinase (MMP)2, and tissue inhibitor of matrix metalloproteinase (TIMP). RESULTS: The increase in medial wall thickness of the pulmonary arteriole in the M+I group was significantly lower than that in the M group on day 7 after infliximab treatment (P<0.05). The number of intra-acinar muscular arteries in the M+I group was lower than that in the M group on days 14 and 28 (P<0.05). Expression levels of TNF-α, ET-1, ERA, and MMP2 were significantly lower in the M+I group than in the M group on day 5, whereas eNOS and TIMP expressions were late in the M group (day 28). CONCLUSION: Infliximab administration induced early changes in pathological findings and expression levels of TNF-α, and MMP2 in a monocrotaline-induced pulmonary hypertension rat model.