Characteristics of the Mycoplasma pneumoniae Epidemic from 2019 to 2020 in Korea: Macrolide Resistance and Co-Infection Trends.

Mycoplasma pneumoniae, a major etiological agent of community-acquired pneumonia, exhibits distinct cyclic epidemic patterns recurring every three to five years. Several cases of co-infection with severe acute respiratory syndrome coronavirus 2 have been reported globally, resulting in unfavorable clinical manifestations. This study investigated the epidemiological features of the recent M. pneumoniae outbreak (May 2019-April 2020) using retrospective data from the last five years. Molecular test data for macrolide resistance and co-infection were obtained from the Seegene Medical Foundation. National medical expenditure and hospitalization rates were analyzed using data from The Health Insurance Review and Assessment Service of Korea. The macrolide resistance rate was 69.67%, peaking at 71.30% during the epidemic period, which was considerably higher than the 60.89% rate during non-epidemic periods. The co-infection rate with other respiratory pathogens was 88.49%; macrolide-resistant M. pneumoniae strains showed a 2.33% higher co-infection rate than the susceptible strains. The epidemic period had 15.43% higher hospitalization and 78.27% higher medical budget expenditure per patient than non-epidemic periods. The increased rates of macrolide resistance and co-infection observed in macrolide-resistant M. pneumoniae during the epidemic period highlight the importance of monitoring future outbreaks, especially considering macrolide resistance and the risk of co-infection with other pathogens.

The prognostic impact of lymphocyte subsets in newly diagnosed acute myeloid leukemia.

BACKGROUND: Tumor-infiltrating lymphocytes, which form a part of the host immune system, affect the development and progression of cancer. This study investigated whether subsets of lymphocytes reflecting host-tumor immunologic interactions are related to the prognosis of patients with acute myeloid leukemia (AML). METHODS: Lymphocyte subsets in the peripheral blood of 88 patients who were newly diagnosed with AML were analyzed by quantitative flow cytometry. The relationships of lymphocyte subsets with AML subtypes, genetic risk, and clinical courses were analyzed. RESULTS: The percentages of T and NK cells differed between patients with acute promyelocytic leukemia (APL) and those with AML with myelodysplasia-related changes. In non-APL, a high proportion of NK cells (>16.6%) was associated with a higher rate of death before remission (P=0.0438), whereas a low proportion of NK cells (≤9.4%) was associated with higher rates of adverse genetic abnormalities (P=0.0244) and relapse (P=0.0567). A multivariate analysis showed that the lymphocyte subsets were not independent predictors of survival. CONCLUSION: Lymphocyte subsets at diagnosis differ between patients with different specific subtypes of AML. A low proportion of NK cells is associated with adverse genetic abnormalities, whereas a high proportion is related to death before remission. However, the proportion of NK cells may not show independent correlations with survival.

Expression of CD154 (CD40L) on stimulated T lymphocytes in patients with idopathic thrombocytopenic purpura.

OBJECTIVES: The role of CD40-CD154 (CD40L) interaction in T cell-dependent humoral immune response is strongly established. Increased expression of CD154 on stimulated T cells is observed in rheumatic diseases and is associated with disease activity. We investigated the expression of CD154 on T cells from idiopathic thrombocytopenic purpura (ITP) patients and assessed the significance of CD154 expression in disease status. METHODS: We enrolled 59 ITP patients, 23 healthy controls, and 19 patients with non-immune thrombocytopenia. Isolated mononuclear cells were stimulated in RPMI medium containing phorbol myristate acetate (PMA) (5 ng/mL) and ionomycin (500 ng/mL) for 2 h at 37°C. The expression of CD154 on CD4(+)T cells was evaluated using flow cytometry and serum soluble CD40L levels were measured. RESULTS: In ITP patients, the percentage of CD4(+) CD154(+) cells and mean fluorescence intensity (MFI) of CD154 on activated CD4(+)T cells was not different from that in the healthy controls and non-immune thrombocytopenia patients. Additionally, the percentage and expression level of CD154 was not different between ITP patients with low platelet counts (<50 000/µL) and those with 50 000/µL or more. Soluble CD40L levels were significantly lower in ITP patients with low platelet counts than in healthy controls, but were not correlated with CD154 expression. CONCLUSION: Increased CD154 expression on CD4(+)T cells was not observed in ITP patients and was not related with low platelet counts. Overexpression of CD154 on CD4(+)T cells is unlikely to be central to the pathogenesis of ITP, and other immune dysfunctions should be targeted for therapy purposes.

Elevated levels of T helper 17 cells are associated with disease activity in patients with rheumatoid arthritis.

BACKGROUND: Interleukin-17 (IL-17)-producing T helper (Th) 17 cells are considered as a new subset of cells critical to the development of rheumatoid arthritis (RA). We aimed to investigate the distribution of Th1 and Th17 cells and their association with disease activity, and determine the Th17-related cytokine levels in the peripheral blood of RA patients. METHODS: Peripheral blood mononuclear cells from 55 RA and 20 osteoarthritis (OA) patients were stimulated with mitogen, and the distributions of CD4(+)Interferon (INF)(+)IL-17(-) (Th1 cells) and CD4(+)INF-IL-17(+) (Th17 cells) were examined by flow cytometry. Serum levels of IL-6, IL-17, IL-21, IL-23, and tumor necrosis factor (TNF)-α were measured by ELISA. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were recorded. The 28-joint disease activity score (DAS28) was also assessed. RESULTS: The median percentage of Th17 cells was higher in RA patients than in OA patients (P=0.04), and in active than in inactive RA (P=0.03), whereas that of Th1 cells was similar in both groups. Similarly, the levels of IL-17, IL-21, and IL-23 were detected in a significantly higher proportion of RA patients than OA patients and the frequencies of detectable IL-6, IL-17, and IL-21 were higher in active RA than in inactive RA group. The percentage of Th17 cells positively correlated with the DAS28, ESR, and CRP levels. CONCLUSIONS: These observations suggest that Th17 cells and Th17-related cytokines play an important role in RA pathogenesis and that the level of Th17 cells in peripheral blood is associated with disease activity in RA.

Analysis of monocyte subsets and toll-like receptor 4 expression in peripheral blood monocytes of women in preterm labor.

Preterm labor is associated with both localized inflammation of the uterus and elevated proinflammatory cytokines. Recently, specific roles have been suggested for distinct monocyte subsets and toll-like receptor 4 (TLR4) expression in inflammation. The aim of this study was to determine whether specific monocyte subsets and increased TLR4 expression in monocyte subsets contribute to preterm labor. The study included 30 preterm labor, 40 full-term labor and 20 pregnant women (not in labor). Four-color flow cytometry was used to examine the distribution of three monocyte subsets (CD14(+)CD16(-), CD14(high)CD16(+), and CD14(low)CD16(+)) and the TLR4 expression in each monocyte subset in each group of women. A larger percentage of CD14(high)CD16(+) cells was found in the preterm labor group than in the other groups (P=0.08, P=0.06). Women in preterm labor also showed significantly higher TLR4 expression in all monocyte subsets and increased fluorescence intensity in the CD14(+)CD16(-) and CD14(high)CD16(+) cells. Expression of TLR4 and mean fluorescence intensity on each monocyte subset were also significantly correlated. We conclude that women with preterm labor have higher CD16 monocytes, with high concomitant expression of CD14 and enhanced TLR4 expression in monocytes, and that monocyte TLR4 levels could be used as a marker to predict preterm delivery.

The tumorigenic, invasive and metastatic potential of epithelial and round subpopulations of the SW480 human colon cancer cell line.

It has been reported that the SW480 human colon cancer cell line consists of E-type and R-type cells. The long-term tumorigenic potential, invasive and metastatic properties of these subclones have not been characterized. E-type and R-type cells were subcloned using limiting dilution methods from parental SW480 cells. The cell growth rate was determined by MTT colorimetric assay, and colony forming efficiency was analyzed using Matrigel-coated plates. The activity of matrix metalloproteinase (MMP) and of urokinase plasminogen activator (uPA) was assessed by zymography. Invasive and locomotive ability was analyzed using transwell chambers. In situ apoptosis detection of these subclones was also performed. In vivo long-term tumorigenicity and nodal metastasis were evaluated using nude mice. E-type cells produced spontaneously regressive tumors in spite of invasion and lymph node metastasis. In contrast, R-type cells revealed progressively growing tumors without invasion or metastasis. E-type cells exhibited increased apoptosis and invasive and motile ability, as well as strong MMP-9 and -2 activity. Although phorbol 12-myristate 13-acetate treatment induced MMP-9 activity in E-type cells, it had no effect on R-type cells. These findings suggest that E- and R-type cells may have different biological properties in terms of colon cancer progression, regression, invasion and nodal metastasis, and might serve as a useful model for these studies.