Can you rely on Treg cells on the rebound?

FoxP3⁺ regulatory T (Treg) cells comprise a highly dynamic population that restrains autoreactivity. Although complete or long‐term depletion of Foxp3⁺CD4⁺ Treg cells in adult mice has been shown to result in chronic inflammation and autoimmune disease, the impact of transient Treg‐cell depletion on self‐reactive responses is poorly defined. A new study published in this issue of the European Journal of Immunology [Eur. J. Immunol. 2014. 44: 3621–3631] shows that, although transient depletion of Treg cells in mice is swiftly followed by recovery of Treg‐cell numbers, the “rebounded” population fails to maintain tolerance, culminating in severe autoimmune gastritis. This commentary explores new questions about the quantitative and qualitative aspects of Treg‐cell function in immunological tolerance raised by this study and others.     

Heterogeneity of Osteosarcoma Cell Lines Led to Variable Responses in Reprogramming

Four osteosarcoma cell lines, Saos-2, MG-63, G-292 and U-2 OS, were reprogrammed to pluripotent state using Yamanaka factors retroviral transduction method. Embryonic stem cell (ESC)-like clusters started to appear between 15 to 20 days post transduction. Morphology of the colonies resembled that of ESC colonies with defined border and tightly-packed cells. The reprogrammed sarcomas expressed alkaline phosphatase and pluripotency markers, OCT4, SSEA4, TRA-1-60 and TRA-1-81, as in ESC up to Passage 15. All reprogrammed sarcomas could form embryoid body-like spheres when cultured in suspension in a low attachment dish for up to 10 days. Further testing on the directed differentiation capacity of the reprogrammed sarcomas showed all four reprogrammed sarcoma lines could differentiate into adipocytes while reprogrammed Saos-2-REP, MG-63-REP and G-292-REP could differentiate into osteocytes. Among the 4 osteosarcoma cell lines, U-2 OS reported the highest transduction efficiency but recorded the lowest reprogramming stability under long term culture. Thus, there may be intrinsic differences governing the variable responses of osteosarcoma cell lines towards reprogramming and long term culture effect of the reprogrammed cells. This is a first report to associate intrinsic factors in different osteosarcoma cell lines with variable reprogramming responses and effects on the reprogrammed cells after prolonged culture.     

Motion‐compensated b‐tensor encoding for in vivo cardiac diffusion‐weighted imaging

Motion is a major confound in diffusion‐weighted imaging (DWI) in the body, and it is a common cause of image artefacts. The effects are particularly severe in cardiac applications, due to the nonrigid cyclical deformation of the myocardium. Spin echo‐based DWI commonly employs gradient moment‐nulling techniques to desensitise the acquisition to velocity and acceleration, ie, nulling gradient moments up to the 2nd order (M2‐nulled). However, current M2‐nulled DWI scans are limited to encode diffusion along a single direction at a time. We propose a method for designing b‐tensors of arbitrary shapes, including planar, spherical, prolate and oblate tensors, while nulling gradient moments up to the 2nd order and beyond. The design strategy comprises initialising the diffusion encoding gradients in two encoding blocks about the refocusing pulse, followed by appropriate scaling and rotation, which further enables nulling undesired effects of concomitant gradients. Proof‐of‐concept assessment of in vivo mean diffusivity (MD) was performed using linear and spherical tensor encoding (LTE and STE, respectively) in the hearts of five healthy volunteers. The results of the M2‐nulled STE showed that (a) the sequence was robust to cardiac motion, and (b) MD was higher than that acquired using standard M2‐nulled LTE, where diffusion‐weighting was applied in three orthogonal directions, which may be attributed to the presence of restricted diffusion and microscopic diffusion anisotropy. Provided adequate signal‐to‐noise ratio, STE could significantly shorten estimation of MD compared with the conventional LTE approach. Importantly, our theoretical analysis and the proposed gradient waveform design may be useful in microstructure imaging beyond diffusion tensor imaging where the effects of motion must be suppressed.     

Expression of S-100 protein in renal cell neoplasms

Polyclonal antibody to S-100 protein has been routinely applied for initial screening of various types of tumors, including, melanocytic tumors and neurogenic tumors. S-100 protein has been shown to have a broad distribution in human tissues, including renal tubules. The potential utility of S-100 protein in renal cell neoplasms has not been extensively investigated. Using an EnVision-Horseradish Peroxidase (HRP; Dako, Carpinteria, Calif) kit, we evaluated the diagnostic value of S-100 protein on tissue microarray sections from 175 cases of renal epithelial neoplasm (145 primary renal neoplasms and 30 metastatic renal cell carcinomas) and 24 non-neoplastic renal tissues. Immunohistochemical stains for pancytokeratin, HMB-45, and Mart-1 were also performed. Western blot using the same antibody (anti-S-100 protein) was performed on 10 cases of renal cell neoplasm. The results demonstrated that nuclear and cytoplasmic staining pattern for S-100 protein was observed in 56 (69%) of 81 conventional (clear cell) renal cell carcinomas (RCCs), 10 (30%) of 33 papillary RCCs, 1 (6%) of 16 ChRCCs, and 13 (87%) of 15 oncocytomas. Among the 81 cases of CRCC, positivity for S-100 protein was seen in 41 (71%) of 58 and 15 (65%) of 23 cases with Furhman nuclear grade I/II and III/IV, respectively. Focal immunostaining was present in 22 (92%) of 24 normal renal tubules. Similar staining pattern was observed in 21 (70%) of 30 metastatic RCCs. Western blotting demonstrated the S-100 protein expression in both renal cell neoplasm and normal renal tissue. Overexpression of S-100 in oncocytomas compared with ChRCCs was confirmed by the data of Western blot and cDNA microarray analysis. Importantly, 14.8% (12/81) of clear cell RCC and 13.3% (4/30) of metastatic RCC revealed an immunostaining profile of pancytokeratin (-)/S-100 protein (+). These data indicate that caution should be taken in interpreting an unknown primary with S-100 positivity and cytokeratin negativity. In addition, it suggests that S-100 has a diagnostic value in differentiating oncocytoma from ChRCC.     

Opinions from ESL instructors and students about curricula on hepatitis B for use in immigrant communities

Background. Chinese immigrants in Canada have a disproportionately high risk for hepatitis B compared with non-Hispanic Whites. Hepatitis B is the leading cause of hepatocellular carcinoma among Asian immigrants to North America. English-as-a-second-language (ESL) classes are an effective way of reaching newly immigrated individuals and are a potential channel for delivering health messages. Methods. Using data from 6 focus groups among ESL instructors and students, we characterized perceptions about activities that are successfully used in ESL classrooms and strategies for delivering hepatitis B information. Results. Instructors and students generally reported that activities that focused on speaking and listening skills and that addressed content relevant to students’ daily lives were successful in the classroom. Instructors generally avoided material that was irrelevant or too difficult to understand. Focus group participants offered strategies for delivering hepatitis B information in ESL classrooms; these strategies included addressing symptoms and prevention and not singling out a specific population subgroup to avoid stigmatization. Conclusions. These findings might assist efforts to develop ESL curricula that target immigrant populations.     

Selective loss of chromosome 11 in pheochromocytomas associated with the VHL syndrome

By using comparative genomic hybridization (CGH), we characterized the genetic profiles of 36 VHL-related pheochromocytomas. We then compared the results with those of sporadic and MEN 2-related pheochromocytomas. In 36 VHL-related tumors, loss of chromosome 3 and chromosome 11 were found in 34 tumors (94%) and 31 tumors (86%), respectively. There was significant concordance of deletions in chromosomes 3 and 11 (Kappa=0.64, P=0.0095), suggesting that they are involved in two different but necessary and complementary genetic pathways. The loss of chromosome 11 appeared to be specific for VHL-related pheochromocytoma as it was not present in any of the 10 VHL-related CNS hemangioblastomas studied and was significantly less common when compared with (a) sporadic pheochromocytomas from previously published results (13%; P=<0.0001), and (b) MEN 2-related pheochromocytomas from this and previously published studies (30%; P=0.0012). In summary, this is the first report of a novel consistent genetic alteration that is selected and specific for VHL-related pheochromocytoma, besides the two hits of the VHL gene.