Targeted deletion of CD244 on monocytes promotes differentiation into anti-tumorigenic macrophages and potentiates PD-L1 blockade in melanoma.

BACKGROUND: In the myeloid compartment of the tumor microenvironment, CD244 signaling has been implicated in immunosuppressive phenotype of monocytes. However, the precise molecular mechanism and contribution of CD244 to tumor immunity in monocytes/macrophages remains elusive due to the co-existing lymphoid cells expressing CD244. METHODS: To directly assess the role of CD244 in tumor-associated macrophages, monocyte-lineage-specific CD244-deficient mice were generated using cre-lox recombination and challenged with B16F10 melanoma. The phenotype and function of tumor-infiltrating macrophages along with antigen-specific CD8 T cells were analyzed by flow cytometry and single cell RNA sequencing data analysis, and the molecular mechanism underlying anti-tumorigenic macrophage differentiation, antigen presentation, phagocytosis was investigated ex vivo. Finally, the clinical feasibility of CD244-negative monocytes as a therapeutic modality in melanoma was confirmed by adoptive transfer experiments. RESULTS: CD244fl/flLysMcre mice demonstrated a significant reduction in tumor volume (61% relative to that of the CD244fl/fl control group) 14 days after tumor implantation. Within tumor mass, CD244fl/flLysMcre mice also showed higher percentages of Ly6Clow macrophages, along with elevated gp100+IFN-γ+ CD8 T cells. Flow cytometry and RNA sequencing data demonstrated that ER stress resulted in increased CD244 expression on monocytes. This, in turn, impeded the generation of anti-tumorigenic Ly6Clow macrophages, phagocytosis and MHC-I antigen presentation by suppressing autophagy pathways. Combining anti-PD-L1 antibody with CD244-/- bone marrow-derived macrophages markedly improved tumor rejection compared to the anti-PD-L1 antibody alone or in combination with wild-type macrophages. Consistent with the murine data, transcriptome analysis of human melanoma tissue single-cell RNA-sequencing dataset revealed close association between CD244 and the inhibition of macrophage maturation and function. Furthermore, the presence of CD244-negative monocytes/macrophages significantly increased patient survival in primary and metastatic tumors. CONCLUSION: Our study highlights the novel role of CD244 on monocytes/macrophages in restraining anti-tumorigenic macrophage generation and tumor antigen-specific T cell response in melanoma. Importantly, our findings suggest that CD244-deficient macrophages could potentially be used as a therapeutic agent in combination with immune checkpoint inhibitors. Furthermore, CD244 expression in monocyte-lineage cells serve as a prognostic marker in cancer patients.

Erratum: Correction of Figure in the Article "Viral, Immunologic, and Laboratory Parameters in Patients With and Without Post-Acute Sequelae of SARS-CoV-2 Infection (PASC)".

This corrects the article on p. e237 in vol. 39, PMID: 39252682.

Viral, Immunologic, and Laboratory Parameters in Patients With and Without Post-Acute Sequelae of SARS-CoV-2 Infection (PASC).

BACKGROUND: The pathophysiological mechanisms underlying the post-acute sequelae of severe acute respiratory syndrome coronavirus 2 infection (PASC) are not well understood. Our study aimed to investigate various aspects of theses mechanisms, including viral persistence, immunological responses, and laboratory parameters in patients with and without PASC. METHODS: We prospectively enrolled adults aged ≥ 18 years diagnosed with coronavirus disease 2019 (COVID-19) between August 2022 and July 2023. Blood samples were collected at three time-points: within one month of diagnosis (acute phase) and at 1 month, and 3 months post-diagnosis. Following a recent well-designed definition of PASC, PASC patients were defined as those with a questionnaire-based PASC score ≥ 12 persisting for at least 4 weeks after the initial COVID-19 diagnosis. RESULTS: Of 57 eligible COVID-19 patients, 29 (51%) had PASC, and 28 (49%) did not. The PASC group had significantly higher nucleocapsid protein (NP) antigenemia 3 months after COVID-19 diagnosis (P = 0.022). Furthermore, several cytokines, including IL-2, IL-17A, VEGF, RANTES, sCD40L, IP-10, I-TAC, and granzyme A, were markedly elevated in the PASC group 1 and/or 3 month(s) after COVID-19 diagnosis. In contrast, the median values of several serological markers, including thyroid markers, autoimmune indicators, and stress-related hormones, were within the normal range. CONCLUSION: Levels of NP antigen and of various cytokines involved in immune responses become significantly elevated over time after COVID-19 diagnosis in PASC patients compared to non-PASC patients. This suggests that PASC is associated with prolonged immune dysregulation resulting from heightened antigenic stimulation.

A natural variation in the RNA polymerase of severe fever with thrombocytopenia syndrome virus enhances viral replication and in vivo virulence.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne disease with high mortality in Eastern Asia. The disease is caused by the SFTS virus (SFTSV), also known as Dabie bandavirus, which has a segmented RNA genome consisting of L, M, and S segments. Previous studies have suggested differential viral virulence depending on the genotypes of SFTSV; however, the critical viral factor involved in the differential viral virulence is unknown. Here, we found a significant difference in viral replication in vitro and virulence in vivo between two Korean isolates belonging to the F and B genotypes, respectively. By generating viral reassortants using the two viral strains, we demonstrated that the L segment, which encodes viral RNA-dependent RNA polymerase (RdRp), is responsible for the enhanced viral replication and virulence. Comparison of amino acid sequences and viral replication rates revealed a point variation, E251K, on the surface of RdRp to be the most significant determinant for the enhanced viral replication rate and in vivo virulence. The effect of the variation was further confirmed using recombinant SFTSV generated by reverse genetic engineering. Therefore, our results indicate that natural variations affecting the viral replicase activity could significantly contribute to the viral virulence of SFTSV.

Fatal outcome of severe fever with thrombocytopenia syndrome (SFTS) and severe and critical COVID-19 is associated with the hyperproduction of IL-10 and IL-6 and the low production of TGF-ß.

Severe fever with thrombocytopenia syndrome virus (SFTSV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can cause the hyperproduction of inflammatory cytokines, which have pathological effects in patient including severe or fatal cytokine storms. To characterize the effect of SFTSV and SARS-CoV-2 infection on the production of cytokines in severe fever with thrombocytopenia syndrome (SFTS) and COVID-19 patients, we performed an analysis of cytokines in SFTS and COVID-19 patients and also investigated the role of interleukin-10 (IL-10) in vitro studies: lipopolysaccharide-induced THP-1-derived macrophages, SFTSV infection of THP-1 cells, and SARS-CoV-2 infection of THP-1 cells. In this study, we found that levels of both IL-10 and IL-6 were significantly elevated, the level of transforming growth factor-ß (TGF-ß) was significantly decreased and IL-10 was elevated earlier than IL-6 in severe and critical COVID-19 and fatal SFTS patients, and inhibition of IL-10 signaling decreased the production of IL-6 and elevated that of TGF-ß. Therefore, the hyperproduction of IL-10 and IL-6 and the low production of TGF-ß have been linked to cytokine storm-induced mortality in fatal SFTS and severe and critically ill COVID-19 patients and that IL-10 can play an important role in the host immune response to severe and critical SARS-CoV-2 and fatal SFTSV infection.

Coinfection of Severe Fever With Thrombocytopenia Syndrome Virus and Coxiella burnetii in Developmental Stage of Hard Ticks in Subtropical Region of Korea.

BACKGROUND: Severe fever with thrombocytopenia syndrome virus (SFTSV) is transmitted through tick bites. Ticks are potential vectors for the bacterium Coxiella burnetii that causes Query fever. Here, we analyzed SFTSV and C. burnetii co-infection rates in ticks in rural areas of Jeju Island, South Korea. METHODS: Free ticks were collected from the natural environment of the island between 2016 and 2019, and SFTSV RNA was extracted. Additionally, ribosomal RNA gene sequencing was used to identify Coxiella species. RESULTS: Haemaphysalis longicornis was the most common tick species followed by H. flava. Tick number gradually increased from April, peaked in August, and was lowest in March. Of all the collected ticks, 82.6% (2,851/3,458) were nymphs, 17.9% (639/3,458) adults, and 0.1% (4/3,458) larvae. SFTSV-infected ticks comprised 12.6% of all ticks; their numbers were the lowest in November-December, increased from January, and were mostly identified in the adult stage during June-August. C. burnetii infections were detected in 4.4% of the SFTSV-infected H. longicornis ticks. C. burnetii co-infection was mainly observed in the nymph stage of H. longicornis, with the highest infection rate in January, followed by December and November. CONCLUSION: Our findings suggest that Jeju Island has a high SFTSV and potential C. burnetii infection in ticks. This study provides important insights regarding SFTS and Q fever risk to humans in South Korea.

Severe Fever with Thrombocytopenia Syndrome Virus Infection, Thailand, 2019-2020.

Infection with severe fever with thrombocytopenia syndrome (SFTS) virus, which can cause hemorrhagic febrile illness, is often transmitted by ticks. We identified 3 patients with SFTS in or near Bangkok, Thailand. Our results underscore a need for heightened awareness by clinicians of possible SFTS virus, even in urban centers.

Bacteroides fragilis Enterotoxin Upregulates Matrix Metalloproteinase-7 Expression through MAPK and AP-1 Activation in Intestinal Epithelial Cells, Leading to Syndecan-2 Release.

Bacteroides fragilis enterotoxin (BFT) produced by enterotoxigenic B. fragilis (ETBF) causes colonic inflammation. BFT initially contacts intestinal epithelial cells (IECs) and affects the intestinal barrier. Although molecular components of the gut epithelial barrier such as metalloproteinase-7 (MMP-7) and syndecan-2 are known to be associated with inflammation, little has been reported about MMP-7 expression and syndecan-2 shedding in response to ETBF infection. This study explores the role of BFT in MMP-7 induction and syndecan-2 release in IECs. Stimulating IECs with BFT led to the induction of MMP-7 and the activation of transcription factors such as NF-κB and AP-1. MMP-7 upregulation was not affected by NF-κB, but it was related to AP-1 activation. In BFT-exposed IECs, syndecan-2 release was observed in a time- and concentration-dependent manner. MMP-7 suppression was associated with a reduction in syndecan-2 release. In addition, suppression of ERK, one of the mitogen-activated protein kinases (MAPKs), inhibited AP-1 activity and MMP-7 expression. Furthermore, the suppression of AP-1 and ERK activity was related to the attenuation of syndecan-2 release. These results suggest that a signaling cascade comprising ERK and AP-1 activation in IECs is involved in MMP-7 upregulation and syndecan-2 release during exposure to BFT.

Severe Fever with Thrombocytopenia Syndrome Virus in Ticks and SFTS Incidence in Humans, South Korea.

During 2016-2018, we collected 3,193 ticks from rural areas in South Korea to investigate the prevalence of severe fever with thrombocytopenia syndrome virus (SFTSV). We detected SFTSV in ticks at an infection rate (IR) of 11.1%. We noted increases in the human IR associated with the monthly SFTSV IR in ticks.

Genotypic Heterogeneity of Orientia tsutsugamushi in Scrub Typhus Patients and Thrombocytopenia Syndrome Co-infection, Myanmar.

Serologic and molecular surveillance of serum collected from 152 suspected scrub typhus patients in Myanmar revealed Orientia tsutsugamushi of genotypic heterogeneity. In addition, potential co-infection with severe fever with thrombocytopenia syndrome virus was observed in 5 (3.3%) patients. Both scrub typhus and severe fever with thrombocytopenia syndrome are endemic in Myanmar.

Bacteroides fragilis Enterotoxin Induces Sulfiredoxin-1 Expression in Intestinal Epithelial Cell Lines Through a Mitogen-Activated Protein Kinases- and Nrf2-Dependent Pathway, Leading to the Suppression of Apoptosis.

Enterotoxigenic Bacteroides fragilis is a causative agent of colitis and secrets enterotoxin (BFT), leading to the disease. Sulfiredoxin (Srx)-1 serves to protect from oxidative damages. Although BFT can generate reactive oxygen species in intestinal epithelial cells (IECs), no Srx-1 expression has been reported in ETBF infection. In this study, we explored the effects of ETBF-produced BFT on Srx-1 induction in IECs. Treatment of IECs with BFT resulted in increased expression of Srx-1 in a time-dependent manner. BFT treatment also activated transcriptional signals including Nrf2, AP-1 and NF-κB, and the Srx-1 induction was dependent on the activation of Nrf2 signals. Nrf2 activation was assessed using immunoblot and Nrf2-DNA binding activity and the specificity was confirmed by supershift and competition assays. Suppression of NF-κB or AP-1 signals did not affect the upregulation of Srx-1 expression. Nrf2-dependent Srx-1 expression was associated with the activation of p38 mitogen-activated protein kinases (MAPKs) in IECs. Furthermore, suppression of Srx-1 significantly enhanced apoptosis while overexpression of Srx-1 significantly attenuated apoptosis during exposure to BFT. These results imply that a signaling cascade involving p38 and Nrf2 is essential for Srx-1 upregulation in IECs stimulated with BFT. Following this upregulation, Srx-1 may control the apoptosis in BFT-exposed IECs.

Endemic Severe Fever with Thrombocytopenia Syndrome, Vietnam.

Severe fever with thrombocytopenia syndrome (SFTS), a tickborne viral disease, has been identified in China, South Korea, and Japan since 2009. We found retrospective evidence of SFTS virus (SFTSV) infection in Vietnam, which suggests that SFTSV infections also occur in Vietnam, where the virus has not been known to be endemic.

Severe Fever with Thrombocytopenia Syndrome Virus Infection, South Korea, 2010.

Severe fever with thrombocytopenia syndrome (SFTS) was reported in China in 2009 and in South Korea in 2012. We found retrospective evidence of SFTS virus infection in South Korea in 2010, suggesting that infections in South Korea occurred before previously reported and were more concurrent with those in China.

Clinical Characteristics of Macrolide-Resistant Mycoplasma pneumoniae from Children in Jeju.

Mycoplasma pneumoniae is the major pathogen of community-acquired pneumonia in children. The prevalence of macrolide-resistant M. pneumoniae (MRMP) is important owing to the limited alternative therapies for children. We analyzed 111 M. pneumoniae obtained from 107 children admitted for lower respiratory tract infection at Jeju National University Hospital between 2010 and 2015. Macrolide resistance of M. pneumoniae was searched for using polymerase chain reaction (PCR) and sequencing. Of 107 clinical M. pneumoniae, 11 (10.3%) carried macrolide resistance mutations in the 23S rRNA gene. All macrolide resistance mutations were A2063G transitions. We found an acquired A2063G mutation of M. pneumoniae from a patient during macrolide treatment. Patients' characteristics and clinical severity did not differ between those with MRMP and macrolide-sensitive M. pneumoniae, with the exception of frequent pleural effusion in the MRMP group. The prevalence of MRMP (10.3%) in Jeju Island was relatively lower than those of surrounding countries in East Asia. Previous antimicrobial usage and timing of diagnostic test should be considered when determining of macrolide resistance of M. pneumoniae.

Severe Fever with Thrombocytopenia Syndrome in Patients Suspected of Having Scrub Typhus.

To determine prevalence of severe fever with thrombocytopenia syndrome in South Korea, we examined serum samples from patients with fever and insect bite history in scrub typhus-endemic areas. During the 2013 scrub typhus season, prevalence of this syndrome among patients suspected of having scrub typhus was high (23.0%), suggesting possible co-infection.

B-cell-activating factor is elevated in serum of patients with myasthenia gravis.

INTRODUCTION: Myasthenia gravis (MG) is a B-cell-mediated autoimmune disease. B-cell-activating factor (BAFF) is a major factor in B-cell development and activation. In this study we investigated serum BAFF levels in MG patients. METHODS: We compared the serum BAFF levels of 20 MG patients with gender-matched healthy controls. We assayed serum concentrations of BAFF and anti-acetylcholine receptor antibody (AChR) titers. RESULTS: Serum BAFF levels of MG patients with AChR antibodies were significantly higher than those of healthy controls. A significant positive correlation was observed between serum BAFF levels and anti-AChR antibody titers. BAFF values did not correlate with disease severity. CONCLUSIONS: BAFF may play a major role in the pathogenesis of MG, and it may provide a potential target for therapy in patients with MG. Muscle Nerve 54: 1030-1033, 2016.

Association between serum mercury concentration and leukocyte differential count in children.

There have been a number of animal studies on the immunological effects of mercury. However, there is a lack of studies investigating the effects of mercury in children. We investigated the association between serum mercury and leukocyte differential count in Korean children. The relationship between mercury and leukocyte differential count (segment, lymphocyte, monocyte, basophil, and eosinophil counts) was analyzed by multivariate linear analysis adjusted for sex, BMI, parental smoking, lead, cadmium, and allergic sensitization in 311 children. Mercury showed a positive correlation with lymphocyte count (coefficient 113.8, 95% confidence interval 26.7-200.9). However, mercury was not associated with total leukocyte, segment, monocyte, basophil, or eosinophil count. Mercury was associated with the increased of lymphocyte count in Korean children. Further studies will be required to ascertain the clinical significance of this association.

Three cases of postoperative septic arthritis caused by Mycobacterium conceptionense in the shoulder joints of immunocompetent patients.

Mycobacterium conceptionense is a species member of Mycobacterium fortuitum complex, a potential pathogen of increasing clinical importance among opportunistic infections. This species causes a wide spectrum of cutaneous and extracutaneous diseases. In this report, we describe three patients who underwent shoulder surgery with postoperative joint infection by M. conceptionense.

Correlation between the Cycle Threshold Values in Detection of Severe Fever with Thrombocytopenia Syndrome Virus Using PowerChekTM SFTSV Real-Time PCR Kit and Viral Load: Prognostic Implications.

BACKGROUND: This study aimed to analyze the correlation between the cycle threshold (Ct) values of severe fever with thrombocytopenia syndrome (SFTS) virus small (S) and middle (M) segments and the SFTS viral load, aiming to estimate the initial viral load and predict prognosis in the early clinical course. METHOD: A retrospective study was conducted with confirmed SFTS patients at Jeju National University Hospital (2016-2022). Patients were categorized into non-fatal and fatal groups. RESULTS: This study included 49 patients with confirmed SFTS (non-fatal group, n = 42; fatal group, n = 7). A significant negative correlation (-0.783) was observed between the log SFTS viral load and Ct values (p < 0.001). This negative correlation was notably stronger in the fatal group (correlation coefficient -0.940) than in the non-fatal group (correlation coefficient -0.345). CONCLUSION: In this study, we established a correlation between SFTS viral load and Ct values for estimating the initial viral load and early predicting prognosis. These results are expected to offer valuable insights for SFTS patient treatment and prognosis prediction.

Association of genetic variation in chitotriosidase with atopy in Korean children.

BACKGROUND: The atopic diseases, which are the most common chronic diseases of childhood, are complex genetic diseases that involve the contribution of multiple genetic factors to disease pathophysiology. Chitotriosidase is involved in innate immunity, but the association of chitotriosidase with allergic diseases remains unclear. OBJECTIVE: To examine the contribution of genetic variation of the chitotriosidase-encoding gene CHIT1 to atopic phenotypes in a Korean cohort of children. METHODS: We identified CHIT1 variations in a Korean population and conducted association analyses using 295 atopic and 242 nonatopic children. An independent replication study was performed using DNA samples from 148 atopic and 243 nonatopic children. All children were unrelated. We performed Western blot analysis in each genotype in vitro to see whether the CHIT1 A442G variation affects the final protein expression levels. RESULTS: In the case-control association analysis, atopy was significantly associated with a single A442G (rs1065761) polymorphism in CHIT1 (odds ratio = 1.32, P = .01). Children with the c.442G risk allele had significantly higher blood eosinophils (P = .001), total serum IgE (P = .007), and eosinophil cationic protein (P = .02) levels. The results of the replication stage analysis confirmed a significant association between the A442G polymorphism and childhood atopy. The joint analysis of the exploratory and replication studies displayed a stronger significant association. The relative protein expression levels of chitotriosidase were significantly higher in both cell lysate and media with the G transfection compared with the wild type. CONCLUSION: These results indicate that the nonsynonymous A442G polymorphism in CHIT1 is associated with risk of atopy.