Bifurcated monocyte states are predictive of mortality in severe COVID-19

Coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 infection presents with varied clinical manifestations1, ranging from mild symptoms to acute respiratory distress syndrome (ARDS) with high mortality2,3. Despite extensive analyses, there remains an urgent need to delineate immune cell states that contribute to mortality in severe COVID-19. We performed high-dimensional cellular and molecular profiling of blood and respiratory samples from critically ill COVID-19 patients to define immune cell genomic states that are predictive of outcome in severe COVID-19 disease. Critically ill patients admitted to the intensive care unit (ICU) manifested increased frequencies of inflammatory monocytes and plasmablasts that were also associated with ARDS not due to COVID-19. Single-cell RNAseq (scRNAseq)-based deconvolution of genomic states of peripheral immune cells revealed distinct gene modules that were associated with COVID-19 outcome. Notably, monocytes exhibited bifurcated genomic states, with expression of a cytokine gene module exemplified by CCL4 (MIP-1β) associated with survival and an interferon signaling module associated with death. These gene modules were correlated with higher levels of MIP-1β and CXCL10 levels in plasma, respectively. Monocytes expressing genes reflective of these divergent modules were also detectable in endotracheal aspirates. Machine learning algorithms identified the distinctive monocyte modules as part of a multivariate peripheral immune system state that was predictive of COVID-19 mortality. Follow-up analysis of the monocyte modules on ICU day 5 was consistent with bifurcated states that correlated with distinct inflammatory cytokines. Our data suggests a pivotal role for monocytes and their specific inflammatory genomic states in contributing to mortality in life-threatening COVID-19 disease and may facilitate discovery of new diagnostics and therapeutics.

Abstract PO-083: Utilizing spatial transcriptomics to elucidate tertiary lymphoid structure heterogeneity in human cancer

Blockade of the inhibitory PD1 pathway on CD8+ and CD4+ tumor infiltrating lymphocytes (TILs) has revolutionized standard of care for cancer patients. However, these approaches only benefit approximately 20% of cancer patients, thus a more comprehensive understanding of the immune response is paramount for the development of new therapeutic approaches and enhancement of the anti-tumor immune response. The presence of tertiary lymphoid structures (TLS) correlates with enhanced anti-tumor immunity and improved prognosis in several solid tumors. These ectopic lymphoid aggregates can exhibit features like secondary lymphoid organs (SLOs), including high endothelial venules, a T cell zone with mature dendritic cells (DCs), and a germinal center (GC) with follicular DCs and B cells, that facilitate the induction of immune responses in situ. Furthermore, the presence of TLS correlate with superior responses to immunotherapy and mature, GC-containing TLS correlate with increased T cell function in human tumors. However, current immunotherapies do not target TLS despite their predominance in the tumor microenvironment (TME) and key role in the adaptive immune response. Developing therapies that adequately induce TLS is limited by a lack of objective, bioinformatic analyses to elucidate the cellular and locational heterogeneity of TLS. TLS differences in composition are thought to define maturation levels i.e. early TLS have B and T cell aggregates but lack follicular DC and GC appear as the TLS mature. However, cellular composition is just one aspect of TLS heterogeneity. To successfully increase mature TLS in cancer patients for maximal humoral immunity, we must first understand the complete transcriptomic and proteomic profile of TLS in cancer patients. We have utilized the innovative Nanostring GeoMx platform to spatially interrogate the transcriptomics and proteomics associated with TLS. By pairing this technology with high level multispectral immunofluorescence via the Vectra Polaris system, we can link TLS heterogeneity to TLS position within the tumor. Further, we can analyze the complete activation profile of B and T cells to understand how TLS heterogeneity affects lymphocyte function. Our data have indicated that TLS can be linked to increased CD8+ T cell infiltrate and function. In fact, when mature TLS are not present, CD8+ T cell and Treg interactions increase, ultimately creating a more immunosuppressive TME. Lastly, utilizing a novel, robust bioinformatic pipeline, we have identified new genes that will aid in an objective definition of TLS. Specifically, CD27 is increased within TLS that are proximal to the tumor compared to those in the normal adjacent tissue. These studies will revolutionize the way in which TLS are defined within the TME, ultimately offering comprehensive gene and protein analysis of TLS that includes spatial geography of the structures and an unbiased, objective definition of TLS for future clinical utility and immunotherapeutic targeting.

Citation Format: Dongyan Liu, Xiang Li, Rajesh Acharya, Ernest M. Meyer, Shelley Reynolds, Ayana Ruffin, Robert L. Ferris, Dario A.A. Vignali, Riyue Bao, Tullia C. Bruno. Utilizing spatial transcriptomics to elucidate tertiary lymphoid structure heterogeneity in human cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on Tumor Heterogeneity: From Single Cells to Clinical Impact; 2020 Sep 17-18. Philadelphia (PA): AACR; Cancer Res 2020;80(21 Suppl):Abstract nr PO-083.

Tumor infiltrating B cells co-localize with CD4 T effector cells within organized tertiary lymphoid structures to present antigen and educate the anti-tumor immune response in human primary tumors

Only 20% of cancer patients produce a durable response to current immunotherapies. Thus, a need exists to develop additional therapeutic strategies to treat these patients, which includes evaluation of other tumor infiltrating immune cells that could further augment the T cell response. Tumor infiltrating B cells (TIL-B) represent a possible target for immunotherapy due to their crucial role in the immune response. In fact, current data demonstrate that detection of TIL-Bs within tertiary lymphoid structures (TLS) correlate with increased survival in patients with solid tumors and enhanced response to anti-PD1 immunotherapy. We hypothesize that TIL-Bs help generate potent, long-term immune responses against cancer by presenting tumor antigens to CD4 TILs within TLS.

We observed increased numbers of activated TIL-Bs in the primary tumors of head and neck squamous cell carcinoma and non-small cell lung cancer patients. We further assessed the transcriptional signature and location of TIL-Bs within the TME and demonstrated that they are adjacent to Th1 and Tfh CD4+ tumor infiltrating lymphocytes (TILs) within organized, germinal center containing TLS. Further, we generated an antigen presentation assay in vitro, and we observed increased CD4+ TIL responses when TIL-Bs presented autologous tumor antigens. These data suggest that TIL-Bs influence the function of CD4+ TILs in patient tumors within TLS. Ultimately, results from this study will increase effective targeting of TIL-Bs within patient primary tumors.

The Itch ubiquitin ligase is required for KSHV RTA induced vFLIP degradation

Expression of Kaposi's sarcoma herpesvirus vFLIP, a potent activator of NFkB signaling, promotes latency. Inhibition of NFkB signaling promotes lytic reactivation. We previously reported that lytic inducer, RTA, inhibits vFLIP induced NFkB signaling by inducing the degradation of vFLIP via the proteasome. Here we report that the cellular ubiquitin ligase, Itch, is required for RTA induced degradation of vFLIP. Expression of either Itch targeting shRNA or a dominant negative mutant of the ubiquitin ligase both increased the stability of vFLIP in the presence of RTA. Itch potently ubiquitinated vFLIP in vivo and in vitro. We provide evidence for interaction between RTA, vFLIP and Itch and we identified an RTA resistant mutant of vFLIP that is unable to interact with Itch. These observations contribute to our understanding of how RTA counteracts the activities of vFLIP.

Gender-associated differences in matriculating and graduating medical students

Data from the 1993 Matriculating Student Questionnaire (MSQ) and the 1994 Medical School Graduation Questionnaire (GQ) of the Association of American Medical Colleges were investigated for differences in responses between men and women. Notable differences were discovered, particularly with regard to career plans and experiences during medical school. Findings from the GQ include that a higher proportion of women rated curricular coverage of numerous subjects inadequate and that women students more frequently reported mistreatment during medical school. Women were also more likely than men to work in clinics serving the indigent and to complete a primary care clerkship. Over 30% of the 1994 women seniors, compared with 18% of the men, planned to pursue generalist careers. The authors discuss the gender-associated differences, with reference to previous studies, and conclude that medical educators should ensure that women have access to the same skill-development opportunities that men do and to a humane learning environment. Moreover, educators should examine what adaptations can encourage students of both genders to develop an ethic of "social responsibility."