Readability of Korean-Language COVID-19 Information from the South Korean National COVID-19 Portal Intended for the General Public: Cross-sectional Infodemiology Study.

BACKGROUND: The coronavirus pandemic has increased reliance on the internet as a tool for disseminating information; however, information is useful only when it can be understood. Prior research has shown that web-based health information is not always easy to understand. It is not yet known whether the Korean-language COVID-19 information from the internet is easy for the general public to understand. OBJECTIVE: We aimed to evaluate the readability of Korean-language COVID-19 information intended for the general public from the national COVID-19 portal of South Korea. METHODS: A total of 122 publicly available COVID-19 information documents written in Korean were obtained from the South Korean national COVID-19 portal. We determined the level of readability (at or below ninth grade, 10th to 12th grade, college, or professional) of each document using a readability tool for Korean-language text. We measured the reading time, character count, word count, sentence count, and paragraph count for each document. We also evaluated the characteristics of difficult-to-read documents to modify the readability from difficult to easy. RESULTS: The median readability level was at a professional level; 90.2% (110/122) of the information was difficult to read. In all 4 topics, few documents were easy to read (overview: 5/12, 41.7%; prevention: 6/97, 6.2%; test: 0/5, 0%; treatment: 1/8, 12.5%; P=.006), with a median 11th-grade readability level for overview, a median professional readability level for prevention, and median college readability levels for test and treatment. Difficult-to-read information had the following characteristics in common: literacy style, medical jargon, and unnecessary detail. CONCLUSIONS: In all 4 topics, most of the Korean-language COVID-19 web-based information intended for the general public provided by the national COVID-19 portal of South Korea was difficult to read; the median readability levels exceeded the recommended ninth-grade level. Readability should be a key consideration in developing public health documents, which play an important role in disease prevention and health promotion.

Hyperhomocysteinemia Concurrent with Metabolic Syndrome Is Independently Associated with Chronic Kidney Disease among Community-Dwelling Adults in an Urban Korean Population.

Elevated homocysteine (Hcy) levels and metabolic syndrome (MetS) are associated with chronic kidney disease (CKD). We investigated the combined effects of hyperhomocysteinemia (HHcy) and MetS on CKD among community-dwelling adults in an urban area of South Korea. We also identified the combination of HHcy and individual MetS components associated with the maximal risk of CKD. A retrospective cross-sectional study involving 19,311 health examinees between 2 January 2011 and 31 December 2015 was conducted. The participants were divided into four groups-namely, the HHcy-/MetS-, HHcy-/MetS+, HHcy+/MetS-, and HHcy+/MetS+ groups. CKD was defined as a low eGFR <60 mL/min/1.73 m2 or albuminuria. The HHcy+/MetS+ group had a higher risk of CKD than the HHcy-/MetS+ group (odds ratio (OR): 1.750, p = 0.002 for males; OR: 3.224, p < 0.001 for females). The HHcy+/MetS+ group had a higher CKD risk than the HHcy+/MetS- group; however, the difference was not statistically significant (OR: 1.070, p = 0.712 for males; OR: 1.847, and p < 0.074 for females). HHcy concurrent with MetS increased the CKD risk. Among the combinations of HHcy and MetS components, the coexistence of HHcy and central obesity had the greatest effect on CKD. Therefore, the timely detection and treatment of HHcy and MetS are important for preventing CKD.

Evaluation of Korean-Language COVID-19-Related Medical Information on YouTube: Cross-Sectional Infodemiology Study.

BACKGROUND: In South Korea, the number of coronavirus disease (COVID-19) cases has declined rapidly and much sooner than in other countries. South Korea is one of the most digitalized countries in the world, and YouTube may have served as a rapid delivery mechanism for increasing public awareness of COVID-19. Thus, the platform may have helped the South Korean public fight the spread of the disease. OBJECTIVE: The aim of this study is to compare the reliability, overall quality, title-content consistency, and content coverage of Korean-language YouTube videos on COVID-19, which have been uploaded by different sources. METHODS: A total of 200 of the most viewed YouTube videos from January 1, 2020, to April 30, 2020, were screened, searching in Korean for the terms "Coronavirus," "COVID," "Corona," "Wuhan virus," and "Wuhan pneumonia." Non-Korean videos and videos that were duplicated, irrelevant, or livestreamed were excluded. Source and video metrics were collected. The videos were scored based on the following criteria: modified DISCERN index, Journal of the American Medical Association Score (JAMAS) benchmark criteria, global quality score (GQS), title-content consistency index (TCCI), and medical information and content index (MICI). RESULTS: Of the 105 total videos, 37.14% (39/105) contained misleading information; independent user-generated videos showed the highest proportion of misleading information at 68.09% (32/47), while all of the government-generated videos were useful. Government agency-generated videos achieved the highest median score of DISCERN (5.0, IQR 5.0-5.0), JAMAS (4.0, IQR 4.0-4.0), GQS (4.0, IQR 3.0-4.5), and TCCI (5.0, IQR 5.0-5.0), while independent user-generated videos achieved the lowest median score of DISCERN (2.0, IQR 1.0-3.0), JAMAS (2.0, IQR 1.5-2.0), GQS (2.0, IQR 1.5-2.0), and TCCI (3.0, IQR 3.0-4.0). However, the total MICI was not significantly different among sources. "Transmission and precautionary measures" were the most commonly covered content by government agencies, news agencies, and independent users. In contrast, the most mentioned content by news agencies was "prevalence," followed by "transmission and precautionary measures." CONCLUSIONS: Misleading videos had more likes, fewer comments, and longer running times than useful videos. Korean-language YouTube videos on COVID-19 uploaded by different sources varied significantly in terms of reliability, overall quality, and title-content consistency, but the content coverage was not significantly different. Government-generated videos had higher reliability, overall quality, and title-content consistency than independent user-generated videos.

Association between Bone Mineral Density and Serum Iron Indices in Premenopausal Women in South Korea.

BACKGROUND: Osteoporosis is characterized by a decrease in bone mineral density (BMD) and increased risk of fragility fractures. Serum iron level may interact with bone health status. This study investigated the correlations of BMD with serum iron level, hemoglobin level, and total iron-binding capacity (TIBC). METHODS: We performed a retrospective analysis of data from the medical records of premenopausal women in South Korea. The women's BMDs and the Z scores of the BMDs were verified using dual-energy X-ray absorption. The participants were stratified into quartiles for analyses of the associations of BMD with serum iron level, TIBC, and hemoglobin level. RESULTS: A simple linear regression analysis revealed associations of changes in BMD with iron level (ß=-0.001, standard error [SE]=0.001, P<0.001), hemoglobin level (ß=0.015, SE=0.003, P<0.001), and TIBC (ß=0.001, SE=0.001, P<0.001). This pattern was also observed in a multiple linear regression analysis. A multivariate logistic regression analysis of iron level and TIBC for low BMD revealed odds ratios of 1.005 (P<0.001) and 0.995 (P<0.001), respectively. CONCLUSION: This study demonstrated clear relationships of changes in BMD with serum iron level and TIBC, and thus confirms the usefulness of these markers in the clinical evaluation of iron storage and BMD in younger women.

Effect of Prognosis Awareness on the Survival and Quality of Life of Terminally Ill Cancer Patients: A Prospective Cohort Study.

BACKGROUND: Physicians and caregivers are conflicted over whether to inform patients that their disease is terminal. Studies examining the effect of awareness of prognosis on the survival and quality of life of terminally ill cancer patients report conflicting results. This study aimed to assess the effects of prognosis awareness on the survival time and psychological health of terminally ill cancer patients. METHODS: Patients in the hospice wards of two general hospitals were asked to complete a questionnaire. All were mentally alert and could express themselves clearly. Awareness of prognosis was defined as knowing both the diagnosis and exact prognosis. Survival time was defined as the time from hospital admission to death. Multiple psychological examinations were conducted to verify the effect of prognosis awareness on psychological health. RESULTS: Of the 98 subjects who met the inclusion criteria, 65 (66.3%) were aware of their terminal status. The patients' awareness was significantly related to survival time after adjusting for clinical variables with a hazard ratio of 1.70 (95% confidence interval [CI], 1.01-2.86). Furthermore, the unaware group had a higher risk of cognitive impairment (Mini-Mental State Examination <24; adjusted odds ratio [aOR], 3.65; 95% CI, 1.26-10.59) and a poorer quality of life (physical component summary of the Short Form 36-item Health Survey <20; aOR, 3.61; 95% CI, 1.12- 11.60) than the aware group. CONCLUSION: Knowledge of the exact prognosis might have a positive effect on the survival and quality of life of terminally ill cancer patients.

Effects of Pet Insects on Cognitive Function among the Elderly: An fMRI Study.

Animal-assisted therapy has positive effects on cognitive function, depression, performance ability, and social functioning in elderly patients. The aim of this study was to evaluate the effects of rearing pet insects on the cognitive function of healthy elderly participants, with fMRI (functional magnetic resonance imaging) being used for this purpose. Community-dwelling right-handed elderly women (≥60 years) with normal cognitive function were enrolled and randomized at a 1:1 ratio into two groups: insect-rearing and control (n = 16) groups, with the insect-rearing group being further classified into two groups for analysis according to the subjects' scores in the Wisconsin Card Sorting Test, WCST) at the baseline fMRI: Insect-rearing group I with a relatively high score (n = 13), and insect-rearing group II with a relatively low score (n = 6). The insect-rearing groups received and reared crickets as pet insects for 8 weeks. The WCST consisted of two variations, a high level baseline (HLB) and semi-WCST version. There was a significant difference accuracy of the HLB-semi-WCST (p < 0.05) in insect-rearing group II after 8 weeks from the baseline test. In the fMRI analysis involving the WCST reaction test, increased activation was observed in the right dorsal lateral prefrontal cortex and parietal cortex in insect-rearing group II when the semi-WCST, rather than the HLB, was performed. Rearing pet insects showed positive effects on executive functions and performance improvement in elderly women. Further larger studies on the effects of pet insects on cognitive function are warranted.

The Association between Mineral and Trace Element Concentrations in Hair and the 10-Year Risk of Atherosclerotic Cardiovascular Disease in Healthy Community-Dwelling Elderly Individuals.

This cross-sectional analysis included 137 Korean subjects aged 60⁻79 years. All subjects underwent anthropometric measurements and laboratory tests. Scalp hair samples were obtained from each individual, the concentrations of 36 minerals and trace elements were analyzed, and 16 ratios of elements were calculated. ASCVD risk was estimated using pooled cohort ASCVD risk assessment equations for 10-year risk profiles. The 137 subjects were divided into three risk groups: low (<5%, n = 28), intermediate (5% to <7.5%, n = 21), and high (≥7.5%, n = 88) risk groups. After adjusting for obesity (BMI ≥ 25 kg/m²) and sex, Na concentration (mg%) in hair was significantly lower in the low-risk (13.91 ± 7.02) than in the intermediate-risk (47.18 ± 8.08) and high-risk (36.76 ± 3.95) groups (p for trend = 0.024). The concentration of K (mg%) in hair was also positively associated with the severity of ASCVD risk (10.50 ± 8.37, 23.62 ± 9.63, 33.31 ± 4.71, respectively; p for trend = 0.017), but their differences were not statistically significant (p = 0.059). By contrast, the levels of Co, U, and Hg, and the Ca/P and Ca/Mg ratios, were negatively correlated with the severity of ASCVD risk (p for trend < 0.05). Mean Na concentration in hair was significantly lower in the low-risk than in the other risk groups. By contrast, Co, U, and Hg concentrations showed significant negative associations with risk severity. Further studies are needed to assess whether dietary modification for trace elements could lower the risk of ASCVD.

The Relationship Between Serum 25-Hydroxyvitamin D Levels and Physical Performance in Community-Dwelling Older Adults.

BACKGROUND: Vitamin D deficiency is a risk factor for musculoskeletal health in older adults. While many studies have explored the relationship between vitamin D deficiency and fractures, few have examined the relationship between vitamin D and physical performance. We, therefore, sought to evaluate the relationship between serum 25-hydroxyvitamin D [25(OH)D] levels and physical performance in community-dwelling older adults. METHODS: A single-center, cross-sectional study was performed using data collected from 132 individuals aged 60 years or older who were living independently and who participated in the National Health Insurance Service health check-up between May and December 2016. Physical performance was assessed using a short physical performance battery (SPPB). Linear regression was used to examine the association between 25(OH)D levels and physical performance after adjustment for sociodemographic variables, behavioral characteristics, and body mass index. RESULTS: Approximately 36.5% of male and 50.7% of females had vitamin D levels indicative of deficiency (serum 25(OH)D <20.0 ng/mL). 25(OH)D levels were significantly associated with the chair stand SPPB scores in male and females but not with those of the walking and balance tests. After adjustment for potential confounders, there remained a linear association between 25(OH)D levels and the chair stand test for both sexes. CONCLUSION: Lower serum 25(OH)D levels were associated with poor physical performance (chair stand score) among community-dwelling older adults in Korea. Further prospective studies are needed to verify these results.

[Associations between Body Mass Index and Chronic Atrophic Gastritis and Intestinal Metaplasia].

BACKGROUND/AIMS: Chronic atrophic gastritis (AG) and intestinal metaplasia (IM) of the stomach are premalignant lesions. The present study aimed to examine the associations between obesity and these lesions. METHODS: A total of 2,997 patients, who underwent gastroscopy, participated in this study, excluding those who had been diagnosed with gastric cancer. Participants were divided into four groups based on their body mass index (BMI). The risk of AG and IM with increasing BMI was analyzed in men and women, separately. RESULTS: The association between BMI and AG was not significant. After adjusting for age, smoking, alcohol, and AG, the odds ratios for IM in the overweight, obesity, and severe obesity groups were 2.25 (95% confidence interval [CI], 1.50-3.37), 2.32 (95% CI, 1.58-3.42), and 4.86 (95% CI, 2.04-11.5) in men, and 2.66 (95% CI, 1.29-5.47), 4.46 (95% CI, 2.28-8.75), and 9.57 (95% CI, 3.26-28.12) in women, compared with the normal BMI group. CONCLUSIONS: Gastric IM was significantly associated with increased BMI.

The Relationship of Caffeine Intake with Depression, Anxiety, Stress, and Sleep in Korean Adolescents.

BACKGROUND: In various studies in adults, caffeine may increase wakefulness and relieve pain, but caffeine overdose can cause many adverse serious effects on health. Caffeine intake has recently been increasing in adolescents. In spite of importance of caffeine effects on Korean adolescents, there are lack of scientific and systematic studies. The purpose of our study was to identify the relationship between caffeine consumption and effects on adolescents. METHODS: We performed study on 234 middle school students at one middle school in Daegu using a self-report questionnaire. We divided students to quartiles according to amount of caffeine intake. We used Beck Depression Inventory (BDI) to evaluate the degree of depression and Beck Anxiety Inventory (BAI) to evaluate the degree of anxiety. We also used Insomnia Severity Scale (ISI) to evaluate the degree of insomnia and Global Assessment of Recent Stress (GARS) to evaluate the stress in students. We used logistic regression analysis to identify the relationship between caffeine consumption and effects. RESULTS: Higher caffeine intake was associated with higher weight, height, lower academic achievement, and higher score in BDI, BAI, ISI, and GARS (P for trend <0.005). Higher caffeine intake quartile was associated with greater odds of having significant depression (BDI ≥10, P for trend=0.011), and insomnia (ISI ≥8, P for trend=0.015) after adjustment for factors that can affect the psychological status. CONCLUSION: We found that caffeine intake is associated weight, height, academic achievement, and higher score in BDI, BAI, ISI, and GARS. Caffeine intake was positively associated with the severity of depression and the severity of insomnia among adolescents in Korean.

Early Development in the Peritoneal Cavity of CD49dhigh Th1 Memory Phenotype CD4+ T Cells with Enhanced B Cell Helper Activity.

The Th cells that regulate peritoneal B-1 cell functions have not yet been well characterized. To address this question, we investigated peritoneal CD4(+) T cells, observed a high frequency of the conjugates of B-CD4(+) T cells in the peritoneal cavity, and identified a population of CD49d(high)CD4(+) T cells that constituted about half of all CD4(+) T cells in the peritoneal cavity, but were rarely found in other compartments. Peritoneal CD49d(high)CD4(+) T cells were CD44(high)CD62L(low); expressed integrin α4ß1 and CXCR3; and rapidly secreted IFN-γ, TNF-α, and IL-2, showing features of proinflammatory Th1 cells. Peritoneal CD49d(high)CD4(+) T cells developed spontaneously, were detected at the age of 12 d, and showed stem cell-like properties. Their development was observed in mice deficient for signaling lymphocytic activation molecule-associated protein, but not in athymic nude mice and mice lacking in expression of MHC class II on thymic epithelial cells. Peritoneal CD49d(high)CD4(+) T cells were more resistant to irradiation and more sensitive to NAD-induced cell death than CD49d(low)CD4(+) T cells. Notably, peritoneal CD49d(high)CD4(+) T cells also showed some characteristics of follicular Th cells, such as the expression of programmed cell death 1, ICOS, IL-21, and CXCR5. Moreover, peritoneal CD49d(high)CD4(+) T cells enhanced the secretion of IgM Abs by B-1a cells and IgG Abs by splenic B cells. These data suggest that peritoneal CD49d(high)CD4(+) T cells may be innate-like CD4(+) T cells, which develop early and have a dual capacity to support both humoral and cellular immunity.

Five hTRPA1 Agonists Found in Indigenous Korean Mint, Agastache rugosa.

Transient receptor potential ankyrin1 (TRPA1) and transient receptor potential vanilloid 1 (TRPV1) are members of the TRP superfamily of structurally related, nonselective cation channels and mediators of several signaling pathways. Previously, we identified methyl syringate as an hTRPA1 agonist with efficacy against gastric emptying. The aim of this study was to find hTRPA1 and/or hTRPV1 activators in Agastache rugosa (Fisch. et Meyer) O. Kuntze (A.rugosa), commonly known as Korean mint to improve hTRPA1-related phenomena. An extract of the stem and leaves of A.rugosa (Labiatae) selectively activated hTRPA1 and hTRPV1. We next investigated the effects of commercially available compounds found in A.rugosa (acacetin, 4-allylanisole, p-anisaldehyde, apigenin 7-glucoside, L-carveol, ß-caryophyllene, trans-p-methoxycinnamaldehyde, methyl eugenol, pachypodol, and rosmarinic acid) on cultured hTRPA1- and hTRPV1-expressing cells. Of the ten compounds, L-carveol, trans-p-methoxycinnamaldehyde, methyl eugenol, 4-allylanisole, and p-anisaldehyde selectively activated hTRPA1, with EC50 values of 189.1±26.8, 29.8±14.9, 160.2±21.9, 1535±315.7, and 546.5±73.0 µM, respectively. The activities of these compounds were effectively inhibited by the hTRPA1 antagonists, ruthenium red and HC-030031. Although the five active compounds showed weaker calcium responses than allyl isothiocyanate (EC50=7.2±1.4 µM), our results suggest that these compounds from the stem and leaves of A.rugosa are specific and selective agonists of hTRPA1.

Modulation of sweet taste by umami compounds via sweet taste receptor subunit hT1R2.

Although the five basic taste qualities-sweet, sour, bitter, salty and umami-can be recognized by the respective gustatory system, interactions between these taste qualities are often experienced when food is consumed. Specifically, the umami taste has been investigated in terms of whether it enhances or reduces the other taste modalities. These studies, however, are based on individual perception and not on a molecular level. In this study we investigated umami-sweet taste interactions using umami compounds including monosodium glutamate (MSG), 5'-mononucleotides and glutamyl-dipeptides, glutamate-glutamate (Glu-Glu) and glutamate-aspartic acid (Glu-Asp), in human sweet taste receptor hT1R2/hT1R3-expressing cells. The sensitivity of sucrose to hT1R2/hT1R3 was significantly attenuated by MSG and umami active peptides but not by umami active nucleotides. Inhibition of sweet receptor activation by MSG and glutamyl peptides is obvious when sweet receptors are activated by sweeteners that target the extracellular domain (ECD) of T1R2, such as sucrose and acesulfame K, but not by cyclamate, which interact with the T1R3 transmembrane domain (TMD). Application of umami compounds with lactisole, inhibitory drugs that target T1R3, exerted a more severe inhibitory effect. The inhibition was also observed with F778A sweet receptor mutant, which have the defect in function of T1R3 TMD. These results suggest that umami peptides affect sweet taste receptors and this interaction prevents sweet receptor agonists from binding to the T1R2 ECD in an allosteric manner, not to the T1R3. This is the first report to define the interaction between umami and sweet taste receptors.

Co-transplantation of human fetal thymus, bone and CD34(+) cells into young adult immunodeficient NOD/SCID IL2Rγ(null) mice optimizes humanized mice that mount adaptive antibody responses.

Both the thymus (T) and bone (B) are necessary hematopoietic niches in adult humans. We previously showed that co-transplantation of human fetal T and B tissues into neonatal immunodeficient NOD/SCID IL2Rγ(null) (NSG, N) mice facilitated hematopoiesis. However, transplantation into neonatal mice resulted in high frequency of early death, making it unrealistic for repetitive experiments. In this study, young adult N mice were pre-engrafted with T and B, T alone, B alone or no tissues. The animals were irradiated and injected with autologous fetal liver (FL)-derived CD34(+) cells (34). The resultant mice were TB34N, T34N, B34N and 34N, respectively, and challenged with T cell dependent antigens (Ags). The humanized TB34N mice showed best performance of these mouse models in many aspects resembling the adult human Ag-experienced spleen. The TB34N mice exhibited better hematopoietic reconstitution; balanced development of T- and B-cell, and common progenitor cells; follicular lymphoid structures with a functional germinal center (GC) enriched with follicular dendritic cells (FDCs) and plasma cells (PCs); secretion of hIgG in the sera in response to Ags at comparable levels to those of human; derivations of hIgG mAb-secreting hybridoma clones. Collectively, the humanized TB34N mice could develop an adaptive immunity that was capable of producing Ag-specific hIgG at a significant level via class switching. This unprecedented TB34N platform in humanized mice would be useful in dissecting human immunity, for generating human Abs and clinical applications.

Reversible expression of CD138 on mature follicular B cells is downregulated by IL-4.

CD138, known as a marker of plasma cells, was reported to be expressed to an intermediate level in the murine bone marrow precursor B cells. Here an intermediate level of CD138 expression was also noted in a subpopulation of splenic follicular B cells, which were distinguishable from CD138(high) plasma cells, whereas the majority of transitional or marginal zone B cells did not express CD138. These CD138(int) B cells were IgM(low)IgD(high) mature B cells, located within follicular B cell zone, and expressed a lower level of CD21 than CD138(-) follicular B cells. During in vitro culture of splenic cells, the proportion of CD138(int) B cells increased, which was noticeably reversed by the addition of IL-4 to the culture. The experiments with sorted CD138(int) cells showed that IL-4-mediated regulation of the CD138 expression was B cell-intrinsic and independent of in vitro B cell death. Our results demonstrate that mouse CD138(int) B cells characterize a subpopulation of IgM(low)IgD(high) mature follicular B cells. The CD138 expression on follicular B cells may represent a reversible status, reflecting a dynamic state probably influenced by IL-4.

LPS-induced migration of peritoneal B-1 cells is associated with upregulation of CXCR4 and increased migratory sensitivity to CXCL12.

B-1 cells, which constitute a predominant lymphocyte subset in serosal cavities and produce most of natural antibodies, are subdivided into the CD5(+) B-1a and CD5(-) B-1b cell subpopulations, but the differential roles of B-1a and B-1b cells are not well understood. We report that B-1a cells preferentially migrate out of the peritoneal cavity and upregulate the expression of CXCR4 with heightened sensitivity to CXCL12 and CXCL13 upon LPS treatment compared to B-1b and B-2 cells. Whereas B-1a cells were slightly more abundant than B-1b and B-2 cells in the homeostatic condition, the number of B-1a cells preferentially decreased 48 hr after LPS treatment. The decrease in the peritoneal B-1a cell number was accompanied with increased migration of B-1a cells toward CXCL-12 and CXCL-13 in in vitro transmigration assay using peritoneal B cells from LPS treated mice. The expression level of CXCR4, but not of CXCR5, was also more prominently increased in B-1a cells upon LPS stimulation. LPS-stimulated B-1a cells did not accumulate in omental milky spots in contrast to B-2 cells. These results suggest that B-1a cells actively migrate out of the peritoneal cavity through the regulation of the migratory responsiveness to chemokines and actively participate in systemic immune responses.

CD4(+) T cells from MHC II-dependent thymocyte-thymocyte interaction provide efficient help for B cells.

Recently, a novel CD4(+) T-cell developmental pathway was reported that generates thymocyte-thymocyte (T-T) CD4(+) T cells. We established a mouse system (CIITA(tg)CIITApIV(-/-)) where thymic positive selection occurred only by major histocompatibility complex (MHC) class II(+) thymocytes. T-T CD4(+) T cells selected via MHC class II-dependent T-T interaction are comprised of PLZF-negative and innate PLZF-positive populations. Until recently, the functional role of the PLZF-negative population was unclear. In this study, we demonstrate that naïve T-T CD4(+) T cells provide B-cell help to a level comparable with that of naïve conventional CD4(+) T cells. Considering the absence of PLZF expression in naïve T-T CD4(+) T cells, these results suggest that PLZF-negative naïve T-T CD4(+) T cells are functionally equivalent to conventional naïve CD4(+) T cells in terms of B-cell help.

P2X7 receptor-dependent ATP-induced shedding of CD27 in mouse lymphocytes.

The ATP-gated P2X7 cell surface receptor belongs to the P2X purinoreceptor family, and is expressed abundantly by immune cells. This receptor is involved in several inflammatory and immunological processes, including the secretion of IL-1 by activated macrophages. Here, we demonstrate that CD27, a cell surface molecule, which is involved in the interaction between immune cells and implicated in the immunological memory of the T and B cells, is released rapidly upon treatment with low ATP concentrations, via the activation of the P2X7 receptor. The surface expression of CD27 on the T and B cells has been shown to be down-regulated as the result of ATP treatment, and the soluble form of CD27 was detected readily in the supernatants of splenocytes, which were cultured along with ATP treatment. The shedding of CD27 was blocked by KN-62, a chemical P2X7 inhibitor, and was also efficiently triggered by treatment with 2,3-O-(4-benzoyl-benzoyl)-ATP. The shedding of CD27 from mouse splenic T cells was observed to occur within 5 min of treatment with 300 microM ATP, whereas treatment with PMA or ionomycin was not determined to trigger the shedding of CD27 until treatment had been applied for a period of at least 2 h. The ATP-induced shedding of CD27 was inhibited by treatment with the matrix metalloprotease inhibitor, GM6001, but not by treatments with BAPTA-AM, wortmannin, SB202190, or PD 98059. Therefore, we concluded that P2X7 receptor stimulation by extracellular ATP results in rapid CD27 shedding via protease activation.