Ki Soo Kang

Self Double-Stranded (ds)DNA Induces IL-1β Production from Human Monocytes by Activating NLRP3 Inflammasome in the Presence of Anti–dsDNA Antibodies

The pathogenic hallmark of systemic lupus erythematosus is the autoimmune response against self nuclear Ags, including dsDNA. The increased expression of the proinflammatory cytokine IL-1β has been found in the cutaneous lesion and PBMCs from lupus patients, suggesting a potential involvement of this cytokine in the pathogenesis of lupus. IL-1β is produced primarily by innate immune cells such as monocytes and can promote a Th17 cell response, which is increased in lupus. IL-1β production requires cleaving pro–IL-β into IL-1β by the caspase-1–associated multiprotein complex called inflammasomes. In this study we show that self dsDNA induces IL-1β production from human monocytes dependent on serum or purified IgG containing anti–dsDNA Abs by activating the nucleotide-binding oligomerization domain–like receptor family pyrin domain–containing 3 (NLRP3) inflammasome. Reactive oxygen species (ROS) and K+ efflux were involved in this activation. Knocking down the NLRP3 or inhibiting caspase-1, ROS, and K+ efflux decreased IL-1β production. Supernatants from monocytes treated with a combination of self dsDNA and anti–dsDNA Ab+ serum promoted IL-17 production from CD4+ T cells in an IL-1β–dependent manner. These findings provide new insights in lupus pathogenesis by demonstrating that self dsDNA together with its autoantibodies induces IL-1β production from human monocytes by activating the NLRP3 inflammasome through inducing ROS synthesis and K+ efflux, leading to the increased Th17 cell response.

U1-Small Nuclear Ribonucleoprotein Activates the NLRP3 Inflammasome in Human Monocytes

The NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome is a caspase-1–containing cytosolic protein complex that is essential for processing and secretion of IL-1β. The U1-small nuclear ribonucleoprotein (U1-snRNP) that includes U1-small nuclear RNA is a highly conserved intranuclear molecular complex involved in splicing pre-mRNA. Abs against this self nuclear molecule are characteristically found in autoimmune diseases like systemic lupus erythematosus, suggesting a potential role of U1-snRNP in autoimmunity. Although endogenous DNA and microbial nucleic acids are known to activate the inflammasomes, it is unknown whether endogenous RNA-containing U1-snRNP could activate this molecular complex. In this study, we show that U1-snRNP activates the NLRP3 inflammasome in CD14+ human monocytes dependently of anti–U1-snRNP Abs, leading to IL-1β production. Reactive oxygen species and K+ efflux were responsible for this activation. Knocking down the NLRP3 or inhibiting caspase-1 or TLR7/8 pathway decreased IL-1β production from monocytes treated with U1-snRNP in the presence of anti–U1-snRNP Abs. Our findings indicate that endogenous RNA-containing U1-snRNP could be a signal that activates the NLRP3 inflammasome in autoimmune diseases like systemic lupus erythematosus where anti–U1-snRNP Abs are present.

U1-Small Nuclear Ribonucleoprotein Activates the NOD-like Receptor Family, Pyrin Domain-Containing 3 Inflammasome in Human Monocytes

The NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome is a caspase-1–containing cytosolic protein complex that is essential for processing and secretion of IL-1β. The U1-small nuclear ribonucleoprotein (U1-snRNP) that includes U1-small nuclear RNA is a highly conserved intranuclear molecular complex involved in splicing pre-mRNA. Abs against this self nuclear molecule are characteristically found in autoimmune diseases like systemic lupus erythematosus, suggesting a potential role of U1-snRNP in autoimmunity. Although endogenous DNA and microbial nucleic acids are known to activate the inflammasomes, it is unknown whether endogenous RNA-containing U1-snRNP could activate this molecular complex. In this study, we show that U1-snRNP activates the NLRP3 inflammasome in CD14+ human monocytes dependently of anti–U1-snRNP Abs, leading to IL-1β production. Reactive oxygen species and K+ efflux were responsible for this activation. Knocking down the NLRP3 or inhibiting caspase-1 or TLR7/8 pathway decreased IL-1β production from monocytes treated with U1-snRNP in the presence of anti–U1-snRNP Abs. Our findings indicate that endogenous RNA-containing U1-snRNP could be a signal that activates the NLRP3 inflammasome in autoimmune diseases like systemic lupus erythematosus where anti–U1-snRNP Abs are present.

Genetic characterization of norovirus GII.4 2006b variants from Jeju island, South Korea.

Ninety‐seven fecal specimens collected from children with acute gastroenteritis between 2007 and 2008 that were found to be negative for group A rotavirus in prescreening by ELISA with VP6‐specific antibody were re‐screened for viruses by reverse transcription (RT)‐PCR. Forty (41.2%) samples were found to be positive for virus by RT‐PCR; of these, norovirus (32.5%, n = 13) and rotavirus (32.5%, n = 13) were the most common, followed by astrovirus (5.0%, n = 2) and enterovirus (2.5%, n = 1). Co‐infection was found in 11 (27.5%) samples. Phylogenetic analyses of the ORF2 nucleotide sequences of 21 norovirus strains showed that 19 (90.5%) belonged to the genogroup GII genotype 4 and two (9.5%) belonged to genogroup GI genotype 4. The GII.4 strains demonstrated high sequence homology and were closely related to new 2006b variants observed in Europe, China, Hong Kong, and Japan in 2006. This study provides new information concerning the recent global epidemic of 2006b strains. J. Med. Virol. 82:1065–1070, 2010.

IL-6 receptor α defines effector memory CD8+ T cells producing Th2 cytokines and expanding in asthma.

RATIONALE Cytokine receptors can be markers defining different T-cell subsets and considered as therapeutic targets. The association of IL-6 and IL-6 receptor α (IL-6Rα) with asthma was reported, suggesting their involvement in asthma. OBJECTIVES To determine whether and how IL-6Rα defines a distinct effector memory (EM) CD8+ T-cell population in health and disease. METHODS EM CD8+ T cells expressing IL-6Rα (IL-6Rα(high)) were identified in human peripheral blood and analyzed for function, gene, and transcription factor expression. The relationship of these cells with asthma was determined using blood and sputum. MEASUREMENTS AND MAIN RESULTS A unique population of IL-6Rα(high) EM CD8+ T cells was found in peripheral blood. These cells that potently proliferated, survived, and produced high levels of the Th2-type cytokines IL-5 and IL-13 had increased levels of GATA3 and decreased levels of T-bet and Blimp-1 in comparison with other EM CD8+ T cells. In fact, GATA3 was required for IL-6Rα expression. Patients with asthma had an increased frequency of IL-6Rα(high) EM CD8+ T cells in peripheral blood compared with healthy control subjects. Also, IL-6Rα(high) EM CD8+ T cells exclusively produced IL-5 and IL-13 in response to asthma-associated respiratory syncytial virus and bacterial superantigens. CONCLUSIONS Human IL-6Rα(high) EM CD8+ T cells is a unique cell subset that may serve as a reservoir for effector CD8+ T cells, particularly the ones producing Th2-type cytokines, and expand in asthma.

Prevalence, Clinical Characteristics, and Management of Functional Constipation at Pediatric Gastroenterology Clinics

The purpose of this study was to investigate the prevalence, clinical characteristics, and management of functional constipation at pediatric gastroenterology clinics. A prospective survey using the Rome III criteria was distributed to a group of parents of children with a constipation history and its control group in May 2008. The mean prevalence of constipation was 6.4%, which was similar to those in other countries. Statistically significant variables for children without constipation were that more children had a body mass index of below the 10th percentile even though they received more mothers care and ate balanced meals compared to the constipation group. Meanwhile, the constipation group frequently showed a history of constipation in infancy, picky-eating, lack of exercise, and retentive posturing. When analyzed with the Rome III criteria, the children showed greater than 60% rate of hard stools, painful stools, a history of large fecal mass in rectum, and its disappearance of constipation symptoms after passing a large stool. Our study found different approaches amongst pediatric gastroenterologists like rectal examinations, disimpaction, or drug treatment. Several factors addressed in our study can provide better guidelines for clinicians treating constipation and its future research.

Precore and Core Promoter Mutations of the Hepatitis B Virus Gene in Chronic Genotype C -Infected Children

The precore (G1896A) and core promoter (A1762T, G1764A) mutations of the hepatitis B virus gene are known to be associated with changes in immunologic phase or the progression to complicated liver disease in adults. We analyzed these mutations in chronically HBV-infected children. Serum was collected from 37 children with chronic HBV infection from March 2005 to September 2008. HBV DNA extraction and nested PCR were followed by sequencing of the PCR products. The children were 6.7 ± 4.6 yr old. All of 37 children had HBV genotype C. Of the cohort, 31 (83.8%) were HBeAg-positive and 6 (16.2%) were HBeAg-negative; the former group comprised 18 (48.6%) who were in the immune-tolerance phase (ITP) and 13 (35.2%) in the immune-clearance phase (ICP). Most of the patients had HBV DNA levels of > 1.0 × 108 copies/mL. In the ITP group, only 1 (5.5%) had core promoter mutations, and none had the precore mutation. In the ICP group, only 2 (15.4%) had core promoter mutations; the remaining 6 patients had HBV DNA levels of < 2.0 × 103 copies/mL and no core promoter/precore mutations. The very low incidence of the precore/core promoter gene mutation, in children, suggests that these mutations may be the result of life-long chronic HBV infection.

DNA Methylation Regulates the Differential Expression of CX3CR1 on Human IL-7Rαlow and IL-7Rαhigh Effector Memory CD8+ T Cells with Distinct Migratory Capacities to the Fractalkine

DNA methylation is an epigenetic mechanism that modulates gene expression in mammalian cells including T cells. Memory T cells are heterogeneous populations. Human effector memory (EM) CD8+ T cells in peripheral blood contain two cell subsets with distinct traits that express low and high levels of the IL-7Rα. However, epigenetic mechanisms involved in defining such cellular traits are largely unknown. In this study, we use genome-wide DNA methylation and individual gene expression to show the possible role of DNA methylation in conferring distinct traits of chemotaxis and inflammatory responses in human IL-7Rαlow and IL-7Rαhigh EM CD8+ T cells. In particular, IL-7Rαlow EM CD8+ T cells had increased expression of CX3CR1 along with decreased DNA methylation in the CX3CR1 gene promoter compared with IL-7Rαhigh EM CD8+ T cells. Altering the DNA methylation status of the CX3CR1 gene promoter changed its activity and gene expression. IL-7Rαlow EM CD8+ T cells had an increased migratory capacity to the CX3CR1 ligand fractalkine compared with IL-7Rαhigh EM CD8+ T cells, suggesting an important biological outcome of the differential expression of CX3CR1. Moreover, IL-7Rαlow EM CD8+ T cells induced fractalkine expression on endothelial cells by producing IFN-γ and TNF-α, forming an autocrine amplification loop. Overall, our study shows the role of DNA methylation in generating unique cellular traits in human IL-7Rαlow and IL-7Rαhigh EM CD8+ T cells, including differential expression of CX3CR1, as well as potential biological implications of this differential expression.

Human monocytes have increased IFN-γ-mediated IL-15 production with age alongside altered IFN-γ receptor signaling.

IL-15 is involved in regulating host defense and inflammation. Monocytes produce the biologically active cell surface IL-15 in response to IFN-γ. Although aging can alter the immune system, little is known about whether and how aging affects IFN-γ-mediated IL-15 production in human monocytes. We showed that monocytes of healthy older adults (age ≥ 65) had increased cell surface IL-15 expression in response to IFN-γ compared to those of healthy young adults (age ≤ 40). This finding stems in part from increased IFN-γ receptor (R)1/2 expression on monocytes in older adults, leading to enhanced STAT1 activation and interferon regulatory factor 1 synthesis with increased IL15 gene expression. Our study suggests that with aging the IFN-γ-mediated IL-15 production pathway in human monocytes is uncompromised, but rather augmented, and could be considered as a therapeutic target point to modulate host defense and inflammation in older adults.

Associations among the Degree of Nonalcoholic Fatty Liver Disease, Metabolic Syndrome, Degree of Obesity in Children, and Parental Obesity

Purpose To analyze the associations among the degrees of nonalcoholic fatty liver disease (NAFLD) by ultrasonography and metabolic syndrome, degrees of obesity in children, and degrees of parental obesity. Methods A total of 198 children with obesity who visited a pediatric obesity clinic were prospectively enrolled in this study. The severity of NAFLD based on ultrasonography was classified into no, mild, moderate, or severe NAFLD group. The degree of obesity based on the percentage over standard weight for height per sex was classified into mild, moderate, or severe. Results Of 132 patients evaluated for the degree of NAFLD and metabolic syndrome, the p-value of correlation between the two factors was 0.009. Therefore, metabolic syndrome might significantly affect the degree of NAFLD. Of 158 patients evaluated for the degree of NAFLD and the degree of obesity, the p-value of correlation between the two factors was 0.122. Of 154 patients evaluated for the degree of obesity and fathers obesity, the p-value was 0.076. Of 159 patients evaluated for the degree of obesity and mothers obesity, the p-value was 0.000, indicating that mothers obesity could significantly affect the degree of obesity in children. Of 142 patients evaluated for the degree of obesity and metabolic syndrome, the p-value was 0.288. Conclusion Metabolic syndrome might significantly affect the degree of nonalcoholic fatty liver in children. In addition, mothers obesity might be a significant factor that affects the degree of obesity in children.