Jong-Baeck Lim

CD4+ T Cell Tolerance to Tissue-Restricted Self Antigens Is Mediated by Antigen-Specific Regulatory T Cells Rather Than Deletion

Deletion of self-antigen-specific T cells during thymic development provides protection from autoimmunity. However, it is unclear how efficiently this occurs for tissue-restricted self antigens, or how immune tolerance is maintained for self-antigen-specific T cells that routinely escape deletion. Here we show that endogenous CD4+ T cells with specificity for a set of tissue-restricted self antigens were not deleted at all. For pancreatic self antigen, this resulted in an absence of steady-state tolerance, while for the lung and intestine, tolerance was maintained by the enhanced presence of thymically-derived antigen-specific Foxp3+ regulatory T (Treg) cells. Unlike deletional tolerance, Treg cell-mediated tolerance was broken by successive antigen challenges. These findings reveal that for some tissue-restricted self antigens, tolerance relies entirely on nondeletional mechanisms that are less durable than T cell deletion. This might explain why autoimmunity is often tissue-specific, and it offers a rationale for cancer vaccine strategies targeting tissue-restricted tumor antigens.

Functional recovery after the transplantation of neurally differentiated mesenchymal stem cells derived from bone barrow in a rat model of spinal cord injury

This study was designed to investigate functional recovery after the transplantation of mesenchymal stem cells (MSCs) or neurally differentiated MSCs (NMSCs) derived from bone marrow in a rat model of spinal cord injury (SCI). Sprague-Dawley rats were subjected to incomplete SCI using an NYU impactor to create a free drop contusion at the T9 level. The SCI rats were then classified into three groups; MSCs, NMSCs, and phosphate-buffered saline (PBS)-treated groups. The cells or PBS were administrated 1 week after SCI. Basso-Beattie-Bresnahan (BBB) locomotor rating scores were measured at 1-week intervals for 9 weeks. Somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs) were also recorded 8 weeks after transplantation. While transplantation of MSCs led to a clear tendency of motor recovery, NMSC-treated rats had significantly improved BBB scores and showed significantly shortened initial latency, N1 latency, and P1 latency of the SSEPs compared to PBS controls. In addition, 5-bromo-2-deoxyuridine (BrdU)-prelabeled MSCs costained for BrdU and glial fibrillary acidic protein (GFAP) or myelin basic protein (MBP) were found rostrally and caudally 5 mm each from the epicenter of the necrotic cavity 4 weeks after transplantation. These results suggest that neurally differentiated cells might be an effective therapeutic source for functional recovery after SCI.

ELISpot for measuring human immune responses to vaccines

The enzyme-linked immunosorbent spot (ELISpot) assay is one of the most commonly used methods to measure antigen-specific T cells in both mice and humans. Some of the primary reasons for the popularity of the method are that ELISpot is highly quantitative, can measure a broad range of magnitudes of response and is capable of assessing critical cellular immune-related activities such as IFN-γ secretion and granzyme B release. Furthermore, ELISpot is adaptable not only to the evaluation of a variety of T-cell functions, but also to B cells and innate immune cells. It is no wonder that ELISpot has evolved from a research tool to a clinical assay. Recent Phase I and II studies of cancer vaccines, tested in a variety of malignancies, have suggested that ELISpot may be a useful biomarker assay to predict clinical benefit after therapeutic immune modulation. This article will discuss the most common applications of ELISpot, overview the efforts that have been undertaken to standardize the assay and apply the method in the analysis of human clinical trials, and describe some important steps in the process of developing a clinical-grade ELISpot.

Role of the tumor microenvironment in the pathogenesis of gastric carcinoma

Gastric carcinoma (GC) is the 4(th) most prevalent cancer and has the 2(nd) highest cancer-related mortality rate worldwide. Despite the incidence of GC has decreased over the past few decades, it is still a serious health problem. Chronic inflammatory status of the stomach, caused by the infection of Helicobacter pylori (H. pylori) and through the production of inflammatory mediators within the parenchyma is suspected to play an important role in the initiation and progression of GC. In this review, the correlation between chronic inflammation and H. pylori infection as an important factor for the development of GC will be discussed. Major components, including tumor-associated macrophages, lymphocytes, cancer-associated fibroblasts, angiogenic factors, cytokines, and chemokines of GC microenvironment and their mechanism of action on signaling pathways will also be discussed. Increasing our understanding of how the components of the tumor microenvironment interact with GC cells and the signaling pathways involved could help identify new therapeutic and chemopreventive targets.

Serum high mobility group box‐1 is a powerful diagnostic and prognostic biomarker for pancreatic ductal adenocarcinoma

Extracellular high mobility group box‐1 (HMGB1) contributes to tumor growth and invasiveness. We evaluated the diagnostic and prognostic ability of serum HMGB1 for pancreatic ductal adenocarcinoma (PDAC). Serum HMGB1 measured by enzyme‐linked immunosorbent assay (ELISA) were compared among normal, chronic pancreatitis, PDAC group in both training (n = 25, each group) and independent validation set (n = 45, each group). To determine the usability of serum HMGB1 as a diagnostic predictor of PDAC, receiver operating characteristic (ROC) curves with sensitivity/specificity and logistic regression were evaluated. To assess the HMGB1‐associated prognosis of PDAC, Kaplan–Meier survival and Cox proportional‐hazards regression were applied. Serum HMGB1 was correlated with presence and advanced‐stage of PDAC. Logistic regression exhibited serum HMGB1 was a remarkable biomarker to predict PDAC as a single or multiple‐markers; sensitivity/specificity of serum HMGB1 were superior to carbohydrate antigen (CA) 19‐9 or carcinoembryonic antigen (CEA) in both training and independent datasets. Kaplan–Meier survival analysis showed PDAC patients with high serum HMGB1 levels (>30 ng/mL; median survival, 192 days) had a worse prognosis than patients with low HMGB1 levels (≤30 ng/mL; 514 days) by log‐rank (P = 0.017). Cox proportional‐hazards model showed the relative hazard ratios in high‐serum HMGB1 group was 3.077 compared with the low‐serum HMGB1 group. In conclusion, serum HMGB1 is a desirable diagnostic and prognostic biomarker for PDAC compared with pre‐existing PDAC biomarkers, CA19‐9 and CEA.

Outbreak by meropenem-resistant Pseudomonas aeruginosa producing IMP-6 metallo-β-lactamase in a Korean hospital

Pseudomonas aeruginosa isolates containing the bla(IMP-6) gene were recovered from 5 patients hospitalized at a tertiary-care hospital in Korea. The bla(IMP-6) gene was in a class 1 integron containing 5 different insert gene cassettes. All of the isolates showed identical pattern in SpeI macrorestriction analysis.

Ex vivo expansion of human umbilical cord blood CD34+ cells in a collagen bead-containing 3-dimensional culture system

Self-renewal of stem cells depends on several critical factors, including the hematopoietic microenvironment, interactions with supporting stromal cells, features of the extracellular matrix, hematopoietic growth factors, and cytokines. Our study investigated the role of artificial 3-dimensional microenvironments as a means of replicating a more physiologic milieu in expansion of cord blood CD34+ cells. In the 3-dimensional model, hematopoietic cells inside collagen beads are exposed to cytokines added to a culture medium. We found that amplification of CD34+ cells with a clonogenic assay, fluorescenceactivated cell sorter analysis, and bone marrow repopulation of NOD/SCID mice showed greater clonogenic ability of cells cultured by the 3-dimensional method compared with the 2-dimensional method. The present study demonstrated that 3-dimensional matrix support may be useful for extended periods in expansion and preservation of stem cells or progenitor cells in vitro.

Composite Three-Marker Assay for Early Detection of Kidney Cancer

Background: Early detection of renal cell carcinoma using serum/plasma biomarkers remains challenging. To validate clinical performance of potential candidate markers for kidney tumors, three-marker assay composed of nicotinamide N-methyltransferase (NNMT), L-plastin (LCP1), and nonmetastatic cells 1 protein (NM23A) was evaluated. Methods: Patients with kidney cancer and control group were included in the clinical evaluation. Participants were divided into cohorts representing the training group of control group including healthy and benign tumors (n = 102) and patients with kidney cancer (n = 87) that were used to identify criteria for scoring. Then, we developed a three-marker assay that was validated with a cohort of test group samples (n = 100). A scoring method based on the cut-point of each of the three markers was used to evaluate the diagnostic performance of the marker combination. Results: Plasma levels of NNMT, LCP1, and NM23A were highly elevated in patients with kidney cancer (P < 0.0001). In 289 blind sample tests with control subjects (n = 175) and patients with kidney cancer (n = 114), the diagnostic accuracy of NNMT alone and the three-marker assay was 0.913 and 0.932, respectively. When 90% specificity was defined, the sensitivity of NNMT and the three-marker assay was 71.9% and 95.7%, respectively. The predictive value of the three-marker assay was 87.2% (+PPV) and 97% (−PPV). Conclusions: The composite assay with NNMT, LCP1, and NM23A was a promising novel serum marker assay for the early detection of malignant kidney tumors covering subtypes of RCC with high diagnostic characteristics. Impact: NNMT/LCP1/NM23A triple markers could be a helpful screening assay to detect early RCC. Cancer Epidemiol Biomarkers Prev; 22(3); 390–8. ©2013 AACR.

Axillary Lymph Node Metastasis: CA-15-3 and Carcinoembryonic Antigen Concentrations in Fine-Needle Aspirates for Preoperative Diagnosis in Patients with Breast Cancer

PURPOSE To assess whether concentrations of the tumor markers breast cancer antigen 15-3 (CA-15-3) and carcinoembryonic antigen (CEA) in fine-needle aspirates (FNAs) differ between benign and malignant lymph nodes and whether FNA concentrations of the tumor markers can improve the sensitivity of axillary lymph node (ALN) FNA in patients with breast cancer. MATERIALS AND METHODS An Institutional Review Board approved this study. All subjects gave written informed consent. Ultrasonographically (US)-guided FNA was performed for 134 ALNs in 134 women (mean age, 49.6 years; range, 28-92 years) with breast cancer. Immediately after obtaining an FNA cytology specimen, the needle was rinsed with 1 mL of normal saline solution. CEA and CA-15-3 concentrations were measured in the washout. Of the 134 ALNs, 86 were malignant and 48 were benign. Sensitivity of FNA cytology alone was compared with the sensitivity of FNA cytology and CEA and CA-15-3 FNA concentrations. RESULTS Patients with a positive metastatic diagnosis had significantly higher FNA concentrations of CEA and CA-15-3 than did those with a negative diagnosis (both P = .02). FNA cytology sensitivity was 87.2%, and the combined sensitivity of FNA cytology and FNA tumor marker concentrations was 96.5% (P = .01). CONCLUSION Evaluation of CEA and CA-15-3 concentrations in FNA could be helpful for the preoperative diagnosis of ALN metastasis in patients with breast cancer. (c) RSNA, 2010.

Comparison of the validity of three biomarkers for gastric cancer screening: carcinoembryonic antigen, pepsinogens, and high sensitive C-reactive protein.

Purpose To identify a desirable serum marker for screening tools for gastric cancer, we evaluated the validity of 3 biomarkers, namely, carcinoembryonic antigen (CEA), pepsinogens (PGs), and high sensitive C-reactive protein (hsCRP). Methods We estimated the mean serum levels of CEA, PGs, and hsCRP and compared the sensitivity and specificity of these 3 biomarkers in 378 subjects who were classified into 7 groups: normal, chronic atrophic gastritis, intestinal metaplasia, adenoma, early gastric cancer (EGC), advanced gastric cancer (AGC) without metastasis, and AGC with metastasis (M1). Results There were no significant differences among the normal, high-risk (chronic atrophic gastritis, intestinal metaplasia, and adenoma), and EGC groups for CEA and hsCRP. However, the levels of CEA were relatively higher in the AGC group with intestinal-type cancer (P<0.01). Likewise, hsCRP was relatively higher in the AGC group with diffuse-type cancer (P<0.01). For the PG I/II ratio, there was no significant difference among the normal, high-risk, and cancer groups, including EGC (P<0.01). In addition, there was a negative correlation with grades (γs=−0.480, P<0.01). However, the PG I/II ratio was relatively less effective in diffuse-type cancer compared with intestinal-type cancer. The combination of serum hsCRP and the PG I/II ratio had a higher sensitivity (77%) than did the PG I/II ratio alone (61%) in diffuse-type cancers. Conclusions The combination of serum hsCRP and PG I/II ratio would be helpful as a screening tool for gastric cancer in high incidence populations and may help to select high-risk subjects in need of further specific invasive screening tools such as endoscopy.