Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer with a mortality rate of ~30%. In ~80% of cases, MCC development is attributed to the integration of Merkel cell polyomavirus (MCPyV) DNA into the host’s genome, leading to the expression of viral oncoproteins and tumorigenesis. Developing treatments that sustain immunity against MCC is imperative to address recurrent and/or progressive disease. In many cancers, tumor-infiltrating B cells have been associated with better prognosis and response to immunotherapies. However, the mechanisms by which B cells contribute to tumor immunity in humans have been difficult to resolve in part due to the inter-patient heterogeneity of tumor-specific antigens. The shared nature of MCPyV tumor antigens in MCC allows for MCC-specific B cell responses to be studied across patients. Using DNA-barcoded and fluorescently labeled viral oncoprotein tetramers, we analyzed the transcriptome, proteome, and receptor repertoire of MCC tumor-infiltrating B cells in 12 patient samples at single-cell resolution. From paired heavy and light chain sequences, we cloned 8 antibodies from B cells specific for the MCPyV oncoproteins to confirm binding to MCC-specific antigens. Transcriptomic and proteomic analyses of MCPyV-specific B cells revealed heterogeneity of intra-tumoral B cell responses. Interestingly, we found that the absence of MCC-specific germinal center (GC) B cells in MCC tumors associates with disease progression: ~80% of patients with no detectable GC B cells had MCC progression within a year post-surgery, whereas patients with detectable GC B cells remained progression-free a year after surgery (n=12, p=0.0043). These results suggest strong synergy between B cells and T cells may regulate tumor growth, as B cells rely on signals presented by T cells to differentiate into GC cells. Our long-term objective is to identify B cell phenotypes associated with anti-MCC responses to develop therapeutics that boost cancer-specific immunity.

Active galactic nuclei (AGN) found at the center of galaxies are a compact region of space that produce significantly higher than normal luminosity. AGN are powered by the accretion of matter into a supermassive black hole and sometimes present winds called outflows. Whether outflows affect the evolution of their host galaxies is still a topic of research. Outflows with speeds of more than 10% the speed of light, called Extremely high-velocity outflows (EHVOs), have not been thoroughly explored, and due to their large energies, they might play a large role in star formation. In the 16th data release of the Sloan Digital Sky Survey, 98 new quasars with EHVOs were identified. With this new sample, I will present the results of my findings on the following questions: (1) What does the average EHVO quasar look like? (2) Do these extreme outflows vary more or less than other previously explored outflows? (3) Can we detect these EHVOs at higher speeds? To answer the first question, I will present a composite of the 16th data release EHVO cases found. To analyze if they vary more often or less than other EHVOs, I will present the results of a longitudinal variability study on the 51 cases that were observed on multiple occasions in the EHVO sample. For the last question, I will show the results of applying code our team has created to remove the Lya lines from our spectra, so the intrinsic ions (such as NV, Lya, OVI) will be easier to analyze at higher speeds.

My project studies Extremely High Velocity Outflows (EHVO) in Quasars. Quasars are particularly interesting due to the fact that they are one the most luminous cosmological objects that we have observed in the universe. They are systems at the centres of galaxies that host supermassive black holes--which have masses that range from millions to billions of solar masses--surrounded by an accretion disk of superheated plasma, gas, and dust. The phenomenon that we are studying are the EHVOs in quasars, which are gas outflows traveling at above 10% of the speed of light from the active central region. My project attempts to answer the question of whether quasars with EHVOs show distinct physical characteristics when compared to Broad Absorption Line Quasi-Stellar Objects (BALQSOs), which are quasars with outflows that show a broad absorption width but at lower outflow speeds, as well as compared to the general parent sample of quasars. We hypothesized that quasars with EHVOs show distinctive physical characteristics when compared to the other quasar categories. To study quasar physical characteristics to test our hypothesis, we used data from the Sloan Digital Sky Survey (SDSS) in the latest data release. Previously, our group has found the measurement values for all quasar samples to be overestimated. Thanks to data provided in Rankine+2020, we developed software and used the data to cross-correlate the values of physical parameters, such as bolometric luminosity (Lbol), Eddington ratio and black hole mass (Mbh). I will present the preliminary results of the analysis on EHVO quasar’s physical properties when compared to BALQSOs and the parent sample. These results suggest that quasars with EHVOs exhibit larger values of their Lbol and Eddington ratio when compared to the other two classes of quasars, while the Mbh parameter does not show significant differences.


 

Quasars are compact regions at the center of a galaxy that have much higher than normal luminosity. Gas outflowing in winds is common in quasars, and it might play a role in regulating the black hole growth and star formation in the host galaxies. In particular, the ones with extremely high speeds (>~0.1c) have not been thoroughly studied and might pose the biggest challenges to the simulations of how these outflows are driven. A 2020 study by Rodríguez Hidalgo et al. identified 40 quasars with Extremely high-velocity outflows (EHVOs) in the 9th data release of the Sloan Digital Sky Survey by detecting absorption in quasar spectra. The C iv emission properties of this sample were examined in a 2022 study by Rodríguez Hidalgo & Rankine. Compared to the general population as a whole, these extreme outflows seem to be more predominant in quasars with large blueshifts of the C iv emission line, an indication of outflows in emission, but the sample was small. My project aims to answer the question: do EHVO quasars show distinct emission features compared with the general population of quasars? To answer this question, I carried out an extension of a 2022 study, but using a larger sample of 98 new EHVOs that we identified from the latest data release. I built on the python code that our team has previously created, which cross-correlates the sample of 6743 quassars from the 2020 study with measurements calculated by a 2020 study by Rankine et al and allows us to place the EHVO quasars in the C IV emission line parameters space (blueshifts vs emission intensity). Potential connection between the maximum EHVO velocity and increasing C IV blueshifts is also explored.