Inherited C-terminal TREX1 variants disrupt homology-directed repair to cause senescence and DNA damage phenotypes in Drosophila, mice, and humans.

Age-related microangiopathy, also known as small vessel disease (SVD), causes damage to the brain, retina, liver, and kidney. Based on the DNA damage theory of aging, we reasoned that genomic instability may underlie an SVD caused by dominant C-terminal variants in TREX1, the most abundant 3'-5' DNA exonuclease in mammals. C-terminal TREX1 variants cause an adult-onset SVD known as retinal vasculopathy with cerebral leukoencephalopathy (RVCL or RVCL-S). In RVCL, an aberrant, C-terminally truncated TREX1 mislocalizes to the nucleus due to deletion of its ER-anchoring domain. Since RVCL pathology mimics that of radiation injury, we reasoned that nuclear TREX1 would cause DNA damage. Here, we show that RVCL-associated TREX1 variants trigger DNA damage in humans, mice, and Drosophila, and that cells expressing RVCL mutant TREX1 are more vulnerable to DNA damage induced by chemotherapy and cytokines that up-regulate TREX1, leading to depletion of TREX1-high cells in RVCL mice. RVCL-associated TREX1 mutants inhibit homology-directed repair (HDR), causing DNA deletions and vulnerablility to PARP inhibitors. In women with RVCL, we observe early-onset breast cancer, similar to patients with BRCA1/2 variants. Our results provide a mechanistic basis linking aberrant TREX1 activity to the DNA damage theory of aging, premature senescence, and microvascular disease.

Analysis of the interaction-length dependence of frequency stability in an iodine-stabilized Nd:YAG laser.

We report a numerical simulation and an experimental study on the interaction-length dependence of frequency stability in an iodine-stabilized neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. A saturation spectroscopy model was used in the simulation to calculate the interaction-length dependence of the linewidth and signal-to-noise ratio of the iodine saturation spectrum. We determined that 2 m was the optimal interaction length for laser-frequency stabilization. We confirmed the simulation results by performing modulation transfer spectroscopy and laser-frequency stabilization using 45-cm- and 2-m-long iodine cells and multipass configurations. The results of this study are useful for designing compact and highly stable iodine-stabilized lasers.

Thoracoscopic esophageal drainage for tracheal compression due to mucocele after esophagogastric bypass: a case report.

BACKGROUND: Esophagogastric bypass is performed for esophageal strictures. Mucus retention, known as mucocele, sometimes occurs at the stricture oral side of the remnant esophagus. It is often asymptomatic and is expected to be naturally decompressed, but it may cause respiratory failure depending on the case. Herein, we report a case in which we successfully performed thoracoscopic esophageal drainage as emergency airway management due to tracheal compression by a mucocele after esophagogastric bypass for unresectable esophageal cancer with esophagobronchial fistula. CASE PRESENTATION: A 56-year-old man underwent esophageal bypass surgery for an unresectable esophageal carcinoma with an esophagobronchial fistula following chemotherapy and radiation therapy. Nine months after bypass surgery, he experienced severe dyspnea due to tracheal compression caused by mucus retention on the oral side of the esophageal tumor. We planned thoracoscopic surgery for mucus retention drainage through the right thoracic cavity to secure the airway as an emergency procedure under general anesthesia. Intubation can be performed safely by guiding bronchoscopy in the semi-supine position. Upper esophageal dilation was observed on the cranial side of the azygos arch. We dissected the mediastinal pleura of the upper thoracic esophagus and exposed its wall. A 12-Fr silicone drain was placed in the esophagus through the right chest wall and 120 ml of white fluid was aspirated. He was discharged 9 days after surgery without complications and resumed treatment with an immune checkpoint inhibitor 23 days after surgery. Thereafter, he continued chemotherapy for esophageal cancer, but died of tumor progression and lung metastasis 35 months after bypass surgery and 25 months after thoracoscopic surgery. CONCLUSIONS: Thoracoscopic esophageal drainage could be performed safely as emergency airway management, shorten the period of discontinuance, and allow cancer treatment to be resumed promptly. We believe that this thoracoscopic procedure is an effective and less invasive method if the percutaneous approach is difficult.

The pathogenetic significance of exhausted T cells in a mouse model of mature B cell neoplasms.

Dysfunctional anti-tumor immunity has been implicated in the pathogenesis of mature B cell neoplasms, such as multiple myeloma and B cell lymphoma; however, the impact of exhausted T cells on disease development remains unclear. Therefore, the present study investigated the features and pathogenetic significance of exhausted T cells using a mouse model of de novo mature B cell neoplasms, which is likely to show immune escape similar to human patients. The results revealed a significant increase in PD-1+ Tim-3- and PD-1+ Tim-3+ T cells in sick mice. Furthermore, PD-1+ Tim-3+ T cells exhibited direct cytotoxicity with a short lifespan, showing transcriptional similarities to terminally exhausted T cells. On the other hand, PD-1+ Tim-3- T cells not only exhibited immunological responsiveness but also retained stem-like transcriptional features, suggesting that they play a role in the long-term maintenance of anti-tumor immunity. In PD-1+ Tim-3- and PD-1+ Tim-3+ T cells, the transcription factors Tox and Nr4a2, which reportedly contribute to the progression of T cell exhaustion, were up-regulated in vivo. These transcription factors were down-regulated by IMiDs in our in vitro T cell exhaustion analyses. The prevention of excessive T cell exhaustion may maintain effective anti-tumor immunity to cure mature B cell neoplasms.

Basolateral protein Scribble binds phosphatase PP1 to establish a signaling network maintaining apicobasal polarity.

Scribble, a member of the LAP protein family, contributes to the apicobasal polarity (ABP) of epithelial cells. The LAP-unique region of these proteins, which is essential and sufficient for ABP, includes a conserved Leucine-Rich Repeat (LRR) domain. The major binding partners of this region that could regulate ABP remain unknown. Here, using proteomics, native gel electrophoresis, and site-directed mutagenesis, we show that the concave surface of LRR domain in Scribble participates in three types of mutually exclusive interactions-(i) homodimerization, serving as an auto-inhibitory mechanism; (ii) interactions with a diverse set of polarity proteins, such as Llgl1, Llgl2, EPB41L2, and EPB41L5, which produce distinct multiprotein complexes; and (iii) a direct interaction with the protein phosphatase, PP1. Analogy with the complex between PP1 and LRR domain of SDS22, a well-studied PP1 regulator, suggests that the Scibble-PP1 complex stores a latent form of PP1 in the basolateral cell cortex. Such organization may generate a dynamic signaling network wherein PP1 could be dispatched from the complex with Scribble to particular protein ligands, achieving fast dephosphorylation kinetics.

Chondrosarcoma Arising from the Posterior Iliac Crest Extending into the Spinal Canal.

Chondrosarcoma is a malignant tumor characterized by the production of a cartilage matrix. Extension into the spinal canal from the extracannular space is seen mainly for neurogenic tumors, but it is rare in nonneurogenic tumors. A 75-year-old woman suffered from sciatic pain and numbness in her lower left extremity. The diagnosis was of a low-grade conventional chondrosarcoma, which originated from the posterior ilium with an intraspinal extension at the level of the sacrum, compressing the cauda equina. The tumor extended further into the S1 sacral anterior foramen, in the shape of a dumbbell. The tumor was resected in several blocks posteriorly, and the dumbbell-shaped tumor in the S1 foramen was resected by widening the S1 foramen from behind. The posterior extension of the iliac tumor seemed prevented by the posterior sacroiliac ligament, and the tumor extended into the canal. Here, we report that the iliac chondrosarcoma extending into the spinal canal is rare for this tumor type. An understating of the tumor extension is important for planning the surgical strategy.

Sorting of cadherin-catenin-associated proteins into individual clusters.

The cytoplasmic tails of classical cadherins form a multiprotein cadherin-catenin complex (CCC) that constitutes the major structural unit of adherens junctions (AJs). The CCC in AJs forms junctional clusters, "E clusters," driven by cis and trans interactions in the cadherin ectodomain and stabilized by α-catenin-actin interactions. Additional proteins are known to bind to the cytoplasmic region of the CCC. Here, we analyze how these CCC-associated proteins (CAPs) integrate into cadherin clusters and how they affect the clustering process. Using a cross-linking approach coupled with mass spectrometry, we found that the majority of CAPs, including the force-sensing protein vinculin, interact with CCCs outside of AJs. Accordingly, structural modeling shows that there is not enough space for CAPs the size of vinculin to integrate into E clusters. Using two CAPs, scribble and erbin, as examples, we provide evidence that these proteins form separate clusters, which we term "C clusters." As proof of principle, we show, by using cadherin ectodomain monoclonal antibodies (mAbs), that mAb-bound E-cadherin forms separate clusters that undergo trans interactions. Taken together, our data suggest that, in addition to its role in cell-cell adhesion, CAP-driven CCC clustering serves to organize cytoplasmic proteins into distinct domains that may synchronize signaling networks of neighboring cells within tissues.

Solitary Metastasis of Hepatocellular Carcinoma to the Rectus Abdominis 13 Years After the Initial Treatment.

Solitary muscle metastasis of hepatocellular carcinoma (HCC) is extremely rare, and late metastasis is also rare. We present a 59-year-old man who had received initial treatment for HCC 13 years previously. Ultrasonography revealed a tumor between the abdominal wall and the liver surface. Tumor resection was performed with suspected intrahepatic metastasis or abdominal wall metastasis of HCC, and the tumor was found to be within the rectus abdominis without an association with the liver. Histologically, the resected material was confirmed to be a muscle metastasis of HCC. We discuss the management of muscle metastasis of HCC.

New Assay System Elecsys Anti-p53 to Detect Serum Anti-p53 Antibodies in Esophageal Cancer Patients and Colorectal Cancer Patients: Multi-institutional Study.

BACKGROUND: Several recent studies suggest that serum anti-p53 antibodies (s-p53-Abs) may be combined with other markers to detect esophageal and colorectal cancer. In this study, we assessed the sensitivity and specificity of s-p53-Abs detection of a new electrochemiluminescence immunoassay (ECLIA; Elecsys anti-p53). METHODS: Elecsys anti-p53 assay was used to analyze the level of s-p53-Abs in blood sera from patients with esophageal or colorectal cancer taken before treatment. Control blood sera from healthy volunteers, patients with benign diseases, and patients with autoimmune diseases served as a reference. In addition, squamous cell carcinoma antigen (SCC-Ag) and cytokeratin 19 fragments (CYFRA21-1) were assessed in patients with esophageal cancer, and carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19-9 were assessed in patients with colorectal cancer. RESULTS: Samples from 281 patients with esophageal cancer, 232 patients with colorectal cancer, and 532 controls were included in the study. The median value of s-p53-Abs in control samples was < 0.02 µg/mL (range < 0.02-29.2 µg/mL). Assuming 98% specificity, the cut-off value was determined as 0.05 µg/mL. s-p53-Abs were detected in 20% (57/281) of patients with esophageal cancer and 18% (42/232) of patients with colorectal cancer. In combination with SCC-Ag and CEA, respectively, s-p53-Abs detected 51% (144/281) of patients with esophageal and 53% (124/232) of patients with colorectal cancer. CONCLUSIONS: The new s-p53-Abs assay Elecsys anti-p53 was useful in detecting esophageal and colorectal cancers with high specificity. Adding s-p53-Abs to conventional markers significantly improved the overall detection rates.

A novel staphylococcal enterotoxin SE02 involved in a staphylococcal food poisoning outbreak that occurred in Tokyo in 2004.

Staphylococcal enterotoxins (SEs) are extracellular proteins, produced mainly by Staphylococcus aureus, which cause staphylococcal food poisoning (SFP) when ingested. Here, a novel SE was identified from two strains, which were identified as the causative microbes of the SFP outbreak that occurred in Tokyo in 2004. Both strains harbored the SEA gene, but its production was lower than that of other SEA-producing SFP isolates. Whole-genome sequencing analysis demonstrated that both strains harbored a SE-like gene besides sea. Phylogenetic analysis revealed that the amino acid sequence deduced from the SE-like gene belonged to the SEB group. Therefore, this gene was presumed to be a novel SE gene and termed "SE02." The stability of SE02 against heating and proteolytic digestions was a little different from that of SEA. SE02 has both superantigenic and emetic bioactivities. Namely, SE02 activated mouse splenocytes and exhibited emetic activity in the common marmoset. SE02 mRNA was highly expressed in both isolates during the exponential phase of cultivation. In addition, SE02 protein was produced at 20 °C and 25 °C, which reflects the actual situation of SFP. SE02 appears to be a novel emetic toxin that was likely the causative toxin in combination with SEA in the SFP outbreak.

Minimally invasive esophagectomy and radical lymph node dissection without recurrent laryngeal nerve paralysis.

BACKGROUND: We introduce a novel operative technique to dissect lymph nodes adjacent to the recurrent laryngeal nerve, referred to as the "native tissue preservation" technique. Using this technique, there was no damage to the recurrent laryngeal nerve, which is maintained in its anatomical position. METHODS: From September 2016 to December 2018, minimally invasive esophagectomy was performed in the left lateral decubitus position in 87 patients with esophageal cancer. The native tissue preservation technique for lymphadenectomy around the recurrent laryngeal nerve was used, and all patients were evaluated for recurrent laryngeal nerve paralysis. RESULTS: Minimally invasive esophagectomy was completed in all patients without conversion to thoracotomy. Although an extended lymphadenectomy was performed in all patients, there were no grade II or higher complications (Clavien-Dindo classification) and no incidence of recurrent laryngeal nerve paralysis. CONCLUSION: The native tissue preservation technique may reduce the incidence of recurrent laryngeal nerve paralysis after minimally invasive esophagectomy with radical lymph node dissection.

Farnesoid X receptor and liver X receptors regulate Oct3/4 expression by multiple feedback regulating system in normal renal-derived cells and renal adenocarcinoma cells.

In this study, we found that nuclear receptors FXR and LXR (originally characterized as regulatory factors involved in cholesterol/bile acid homeostasis) regulate the expression of Oct3/4, a marker for cell differentiation, in both normal renal-derived cell line HK-2 and renal adenocarcinoma cell line ACHN. Down-regulation of Oct3/4 expression by activating FXR and LXR occurs only in normal renal cell-derived HK-2 cells. We also found that the RNA-binding protein, ELAVL2, oppositely regulates Oct3/4 expressions in HK-2 and ACHN cells. Moreover, we revealed that LXR-alpha and LXR-beta regulate each other's expression. Although an LXR-beta-specific agonist is assumed to be the basis for an anti-arteriosclerotic drug that only stimulates reverse cholesterol transport, our findings show that the development of such an anti-arteriosclerotic drug would require further elucidation of the complex mechanism of LXR-alpha and LXR-beta regulation.

Multiple ß-Lactam Resistance Gene-Carrying Plasmid Harbored by Klebsiella quasipneumoniae Isolated from Urban Sewage in Japan.

The continuous emergence of carbapenemase-producing Enterobacteriaceae (CPE) presents a great public health challenge. Mitigation of CPE spread in the environment is crucial, particularly from a One Health perspective. Here we describe the isolation of CPE strain SNI47 from influent water of a sewage treatment plant in Japan. SNI47 was identified as Klebsiella quasipneumoniae subsp. quasipneumoniae by phylogenetic analysis and was resistant to ß-lactams, including carbapenems. Of four plasmids detected from SNI47, the 185,311-bp IncA/C2 plasmid (pTMSNI47-1), which carried 10 drug resistance genes, including genes for four ß-lactamases (blaCTX-M-2, blaDHA-1, blaKHM-1, and blaOXA-10), was transferred to Escherichia coli J53 via conjugation. The MICs of all tested ß-lactams for the transconjugant were higher than for the recipient. We constructed recombinant plasmids, into which each ß-lactamase gene was inserted, and used them to transform E. coli DH5α cells, demonstrating that KHM-1 enhanced carbapenem resistance. In addition, these ß-lactamases were responsible for a wide-spectrum ß-lactam resistance acquisition with mutual compensation. KHM-1, recognized as a rare type of metallo-ß-lactamase, was detected in a transferable plasmid, from a sewage treatment plant, involved in horizontal gene transfer. The detection of such plasmids raises a health risk alarm for CPE dissemination.IMPORTANCE In our investigation of urban wastewater in Japan, carbapenem-resistant Klebsiella quasipneumoniae subsp. quasipneumoniae was isolated that carried the pTMSNI47-1 plasmid, which carries four ß-lactamase genes and has transferability among Enterobacteriaceae pTMSNI47-1 was found to encode a rarely reported carbapenemase, KHM-1. Cooperative effects of ß-lactamases encoded by pTMSNI47-1 appeared to have broad-spectrum resistance to ß-lactams. The detection of the KHM-1 gene in urban wastewater suggests that such a rare antimicrobial resistance (AMR) gene can be pooled in the environment, potentially emerging as an AMR determinant in a pathogen. When the number of ß-lactamase resistance genes is increased in one plasmid, the transfer of this plasmid can confer broad-spectrum resistance to ß-lactams, even if the individual gene confers narrow-spectrum resistance. The present study adds important information about the potential risk of sewage treatment plants as reservoirs and environmental suppliers of AMR genes, contributing to the public health from a One Health perspective.

Association of Anoxybacillus sp. with acid off-flavor development in a spoiled, boiled, rice dish.

Off-flavor is one of the most common food complaints. In this study, we demonstrated that acetic acid produced by Anoxybacillus sp. contamination of takikomi-gohan (boiled rice with sweet potato mixed in advance) was considered the causative agent of acid off-flavor development. First, we conducted whole genome sequencing of the bacterial strain (S1674) isolated from the remains of the contaminated takikomi-gohan, and phylogenetic analysis of k-mer diversity demonstrated that S1674 belongs to the Anoxybacillus genus. Gene expression analysis of S1674 RNA sequencing (RNA-seq) and quantitative reverse transcription polymerase chain reaction (qRT-PCR) indicated that the genes encoding enzymes responsible for acetic acid formation, namely ackA1, eutD, pflA, pflB, and pykA, were upregulated in high-temperature cultures in Thermus medium supplemented with soluble starch. Additionally, we succeeded in reproducing the acid off-flavor by adding S1674 to boiled rice stored at 37 °C, 45 °C, and 60 °C. The most strongly detected organic acid was acetic acid, at the odor threshold value or more in both the air and condensation samples. Our findings suggest that some Anoxybacillus sp. produce acetic acid as a byproduct of carbohydrate metabolism, potentially causing the complaint of acid off-flavor even under high-temperature conditions in which other bacteria cannot survive.

Food poisoning outbreak in Tokyo, Japan caused by Staphylococcus argenteus.

Staphylococcus argenteus is a novel species subdivided from Staphylococcus aureus. Whether this species can cause food poisoning outbreaks is unknown. This study aimed to investigate the enterotoxigenic activities of two food poisoning isolates suspected to be S. argenteus (Tokyo13064 and Tokyo13069). The results for phylogenic trees, constructed via whole genome sequencing, demonstrated that both isolates were more similar to a type strain of S. argenteus (MSHR1132) than any S. aureus strain. Moreover, the representative characteristics of S. argenteus were present in both strains, namely both isolates belong to the CC75 lineage and both lack a crtOPQMN operon. Thus, both were determined to be "S. argenteus." The compositions of the two isolates' accessory elements differed from those of MSHR1132. For example, the seb-related Staphylococcus aureus pathogenicity island, SaPIishikawa11, was detected in Tokyo13064 and Tokyo13069 but not in MSHR1132. Both isolates were suggested to belong to distinct lineages that branched off from MSHR1132 lineages in terms of accessory elements. Tokyo13064 and Tokyo13069 expressed high levels of s(arg)eb and produced S(arg)EB protein, indicating that both have the ability to cause food poisoning. Our findings suggest that S. argenteus harboring particular accessory elements can cause staphylococcal diseases such as food poisoning, similarly to S. aureus.

A long-term survival case after surgical resection of skeletal muscle metastasis following esophagectomy for squamous cell carcinoma of the esophagus.

Cases of skeletal muscle metastasis of esophageal carcinoma are very rare, with few reports of long-term survival. We report a case of long-term survival after surgical resection of skeletal muscle metastasis. A 56-year-old man with advanced esophageal cancer and early gastric cancer underwent thoracoscopic esophagectomy, 2-field lymph node dissection, partial gastrectomy and gastric tube reconstruction. Six months later, cervical lymph node metastasis and mediastinal lymph node recurrence were found. Therefore, the patient underwent cervical lymph node dissection and adjuvant chemoradiotherapy. Two years and 3 months after the esophagectomy, a muscle metastasis was found in the left shoulder, and he underwent tumor dissection, followed by adjuvant chemotherapy for a year. There has been no sign of recurrence since, even 13 years after the esophagectomy. We believe our aggressive surgical treatment might have led to long-term survival.

Evaluation of the Infection Risk in Dialysis and Chronic Kidney Disease Patients Using an ATP Monitoring Assay.

The ATP monitoring assay is a useful biomarker for risk monitoring to detect infection and rejection episodes in transplant recipients. Hemodialysis patients have a higher rate of infectious mortality. Infections in hemodialysis patients are mainly caused by venous catheters, uremia, malnutrition and inflammation. However, the risk of infection episodes has not been evaluated using a lymphocyte ATP monitoring assay in hemodialysis and chronic kidney disease (CKD) patients. We measured the ATP amounts in the peripheral CD4+ cells of CKD (N = 85) and dialysis patients (N = 17) using an "Immuknow" assay kit. These CKD patients were divided, according to kidney disease stage, into G3a, G3b, G4, and G5 groups. The ATP amounts in CD4+ cells of the dialysis patients and each of the CKD groups were compared with healthy subjects. In both the dialysis and CKD patients, the ATP amounts in CD4+ cells were lower than in healthy subjects. Furthermore, there were significant differences in the ATP amounts between healthy subjects and each of the CKD-G3a, CKD-G3b, and CKD-G4 groups (P < 0.05). Patients with CKD-G3a, CKD-G3b and CKD-G4 were evaluated as being at high risk for infection according to the lymphocyte ATP monitoring assay. However, the ATP amounts in the dialysis and CKD-G5 patients did not differ from those in healthy subjects to a statistically significant extent. These results suggest that the ATP amount in the CD4+ cells of these patients with serve renal failure are influenced by dialysis treatment, uremia and/or oxidative stress.

[Serial Food Poisoning Outbreaks Caused by Norovirus-Contaminated Shredded Dried Laver Seaweed Provided at School Lunch, Tokyo, 2017].

In February 2017, four food poisoning outbreaks occurred in Tokyo, involving ten schools. Shredded dried laver seaweed processed by a single food manufacturer in December 2016 was provided in common for the school meals that caused all four outbreaks. Of 4,209 persons exposed, 1,193 (28.3%) had symptoms of gastroenteritis. Norovirus (NoV) GII was detected in 207 (78.1%) of 265 cases by real-time RT-PCR. Thirty-one shredded dried laver seaweed samples were examined and seven (22.6%) of them were positive for NoV GII. PCR fragments of NoV ORF1/2 junction region (302 bp) from seven shredded dried laver seaweed samples and 20 clinical samples derived from the four outbreaks were sequenced. All of them displayed complete homology, and the genotype was classified as GII.17. A nearly full-length sequence (7,420 bp) of NoV RNA derived from a case was obtained by next-generation sequencer analysis and phylogenetic analysis indicated that this strain belongs to the same cluster as Hu/GII/JP/2015/GII.P17_GII.17/Kawasaki308. Thus, our investigation elucidated that the causative agent of these four serial food poisoning outbreaks was NoV GII.17 and the infectious source was a single batch of shredded dried laver seaweed. The water activity of the shredded dried laver seaweed was found to be 0.119 to 0.129. It was epidemiologically clarified that NoV does not lose infectivity for about two months even in the dry state. We conclude that a large diffuse outbreak of food poisoning caused by NoV GII.17 contamination of shredded dried laver seaweed had occurred in Tokyo. Our elucidation of the causative agent indicated that the food poisoning outbreaks in multiple areas of Japan, including Tokyo, during January to February 2017 were caused by the same contaminated food.

Effects of arsenic disulfide on proliferation, cytokine production, and frequencies of CD4(+), CD8(+), and regulatory T cells in mitogen-activated human peripheral blood mononuclear cells.

Influence of arsenic disulfide (As2S2) on human immune cells has little been investigated. Effects of As2S2 on proliferation, cytokine production, and frequencies of CD4(+) T, CD8(+) T and CD4(+)CD25(+)Foxp3(+) regulatory T cells in mitogen-activated human peripheral blood mononuclear cells were examined. Anti-proliferative effects of As2S2 on peripheral blood mononuclear cells activated by T-cell mitogen were assessed by a colorimetric assay. Cytokine concentrations in the culture medium were measured with beads-array procedures followed by flow cytometry. CD4(+) T cells, CD8(+) T cells and CD4(+)CD25(+)Foxp3(+) regulatory T cells were stained with fluorescence-labeled specific antibodies followed by flow cytometry analysis. As2S2 at 1-10µM significantly suppressed mitogen-activated proliferation of peripheral blood mononuclear cells (p<0.05). As2S2 at 10µM inhibited production of IL-6, -10, -17A, tumor necrosis factor-α, and interferon-γ from the activated peripheral blood mononuclear cells, though the effects were not statistically significant. As2S2 at 10µM significantly suppressed the frequencies of CD4(+) T and CD8(+) T cells (p<0.05), whereas significantly enhanced the frequency of CD4(+)CD25(+)Foxp3(+) regulatory T cells (p<0.05). The data suggest that As2S2 attenuates T cell-mediated immunity by not only suppressing the proliferation of T cells and cytokine release but also increasing the frequency of regulatory T cells. T cell-mediated autoimmunity contributes to bone marrow failure in myelodysplastic syndrome (MDS), and thus the above As2S2 effects are beneficial for the treatment of MDS patients.