Faculty Bibliography

Thoracic SMARCA4-deficient undifferentiated tumor (SMARCA4d-UT) is an uncommon, aggressive lung neoplasm associated with smoking and characterized by loss of SMARCA4 (BRG-1) expression. Although originally considered to be a primary sarcoma, there is growing evidence that these lesions may represent transformation of conventional non-small cell carcinoma. In this study, we probe this relationship based on the clinical, histologic and molecular findings of 18 SMARCA4-deficient malignancies of the lung. Cases diagnosed as SMARCA4d-UT and SMARCA4-deficient carcinoma were retrospectively reviewed, including histologic and immunophenotypic features, and next generation sequencing studies. Of the 18 tumors, 5 were considered to represent undifferentiated SMARCA4d-UT, and 13 SMARCA4-deficient carcinomas, including 11 adenocarcinomas, 1 squamous cell carcinoma, and 1 poorly differentiated non-small cell carcinoma. All 13 carcinomas had a morphologically identifiable undifferentiated component. Survival outcomes were similar in both SMARCA4d-UT and carcinomas. Genetic alterations often seen in lung cancer were identified in 8 cases, including mutations in EGFR (in 2 SMARCA4-deficient adenocarcinomas), KRAS (1 SMARCA4d-UT and 1 SMARCA4-deficient adenocarcinoma), MAP2K1 (1 SMARCA4-deficient adenocarcinoma), and a gene fusion involving EML4::ALK (1 SMARCA4d-UT). The patient with EML4::ALK fusion was treated with alectinib with partial response. Fusions involving BRAF::CHCHD3 and FGFR1::FILIP1 were identified in 2 SMARCA4-deficient adenocarcinomas. High expression of PD-L1 (TPS >50 %) was seen in 12 cases (67 %). These finding further suggest that SMARCA4d-UT and carcinomas with SMARCA4 loss may be on the same spectrum of disease, and accurate histologic distinction between these lesions may be challenging. A unified terminology may be beneficial for appropriate diagnosis and treatment.

BACKGROUND:Porcine genome editing has revolutionized xenotransplantation, recently enabling the first pig-to-human heart xenotransplants. However, the xeno-immune response in heart xenografts remains largely unexplored. This study aimed to precisely characterize the xeno-immune response and injury in two heart xenografts, transplanted from 10-gene-edited pigs into brain-dead human recipients. METHODS:We analyzed xenograft biopsies at 66-hour post-reperfusion using a multimodal phenotyping approach combining: morphological evaluation, immunophenotyping, ultrastructural assessment, automated quantification of multiplex immunofluorescence staining and gene expression profiling. Xenografts before implantation and wild-type pig hearts with and without ischemia reperfusion injury and brain death were used as controls. RESULTS:Both xenografts showed evidence of endothelial activation and mild microvascular inflammation without capillary C4d deposition. Immune infiltrates were mainly composed of CD15+ and CD68+ innate immune cells. Ultrastructural assessment showed endothelial swelling with occasional intravascular leucocytes. Deep-learning based automated multiplex immunofluorescence analysis confirmed that microvascular inflammation was primarily associated with CD15+ and CD68+ innate immune cells. Both xenografts showed increased expression of genes and pathways associated with monocyte/macrophage activation, neutrophil activation, interferon-gamma response, natural killer cell burden, endothelial activation, apoptosis and injury repair. This phenotype was absent in all control pig hearts, independently from ischemia reperfusion injury and brain death. CONCLUSIONS:Multimodal phenotyping of pig-to-human heart xenografts revealed early signs of xeno-immune response, characterized by mild innate microvascular inflammation, endothelial activation, and molecular signature characteristic of antibody-mediated rejection. Developing such precision diagnostic system could improve graft monitoring in future clinical settings.

There is a body-wide network of interstitial spaces that includes three components: a large-scale fascial network made up of fluid-filled spaces containing collagens and other extracellular matrix components like hyaluronic acid (HA), the peri-vascular/capillary interstitium, and intercellular interstitial spaces. Staining for HA within the colon, skin, and liver has demonstrated spatial continuity of the fascial interstitium across tissue layers and between organs, while continuity of HA staining between perineurial and adventitial sheathes beyond organ boundaries confirmed that they also participate in this body-wide network. We asked whether the pulmonary interstitium comprises a continuous organ-wide network that also connects to the body-wide interstitium via routes along nerves and the vasculature. We studied archival lung lobectomy specimens containing normal tissues inclusive of all lung anatomical units from six females and three males (mean age 53+/- 16.5 years). For comparison, we also studied normal mouse lung. Multiplex immunohistochemical cocktails were used to identify: (1) HA, CD34, and vimentin - highlighting interstitium; (2) HA, CD34, and podoplanin (D2-40) - highlighting relationships between the interstitium, vasculature, and lymphatics. Sizes of extracellular APP were measured. Tissues from nine patients (six females, three males, mean age 53+/- 16.5 years) were studied. HA staining was continuous throughout the five major anatomic compartments of the lung: alveolar walls, subpleural connective tissue, centrilobular peribronchovascular compartment, interlobular septal compartment, and axial peribronchovascular of the hilum, with similar findings in murine lung tissue. Continuity with interstitial spaces of the perineurium and adventitia was confirmed. The distribution of APP corresponded to known routes of lymphatic drainage, superficial and deep. APP within perineurium and perivascular adventitia further demonstrated continuity between intra- and extrapulmonary interstitium. To conclude, all segments of the lung interstitium are connected and are linked along nerves and the vascular tree to a body-wide communication network. These findings have significant implications for understanding lung physiology and pathobiology, suggesting routes of passage for inflammatory cells and mediators, malignant cells, and infectious agents. Interstitial spaces may be important in microbiome signaling within and beyond the lung and may be a component of the lung-brain axis.

BACKGROUND/UNASSIGNED:A thymoma is a tumor originating from thymic epithelial cells variably associated with non-neoplastic lymphocytes. T-lymphoblastic leukemia/lymphoma (T-LBL) is thought to arise from precursor T-cells from bone marrow-derived hematopoietic stem cells that migrate to the thymus. While the association of secondary hematopoietic malignancies in thymoma is well established, only rarely in the literature have T-LBL and thymoma been seen in association and the relationship is poorly understood. Occasionally, distinction between the two can be difficult as immature lymphocytes in thymoma resemble T-LBL both morphologically and immunophenotypically. An accurate diagnosis is essential as treatments vary between these two entities. CASE DESCRIPTION/UNASSIGNED:We present the interesting case of a 64-year-old male, former smoker, originally from Uzbekistan, with a mediastinal mass diagnosed as small cell carcinoma in his home country and treated with chemotherapy. After immigrating to the United States, a positron emission tomography (PET) scan demonstrated a large, metabolically active mediastinal mass. He presented to our institution where a biopsy with histomorphologic and immunohistochemical analysis was diagnostic of type B1 thymoma. He was lost to follow-up, but represented months later with B symptoms. Flow cytometry, cytogenetics, and bone marrow biopsy were diagnostic of T-LBL. Although he was started on chemotherapy, his disease progressed and he expired 6 months after initial presentation. Post-mortem analysis of the mediastinal mass revealed the co-occurrence of benign thymocytes and neoplastic T-LBL lymphoblasts, further confirmed as two distinct entities by T-cell receptor (TCR) sequencing. CONCLUSIONS/UNASSIGNED:Co-occurrence of thymoma and T-LBL is a well-documented, though poorly understood, phenomenon. Literature review for this phenomenon reveals that type B thymoma is most commonly associated with T-LBL in these co-occurrences. Most cases are diagnosed synchronously, though in metachronous cases, the diagnosis of thymoma has always preceded the diagnosis of T-LBL. Of note, recently developed LMO2 immunohistochemical stain is positive in malignant lymphoblasts but negative in benign thymocytes, allowing for post-mortem evaluation of this case to be determined as a synchronous presentation. These entities are difficult to distinguish and require a multimodal diagnostic approach including histology, immunohistochemistry, flow cytometry, cytogenetics, and TCR sequencing.

Immune checkpoint inhibitor (ICI) therapies can increase the risk of cardiovascular events in survivors of cancer by worsening atherosclerosis. Here we map the expression of immune checkpoints (ICs) within human carotid and coronary atherosclerotic plaques, revealing a network of immune cell interactions that ICI treatments can unintentionally target in arteries. We identify a population of mature, regulatory CCR7⁺FSCN1⁺ dendritic cells, similar to those described in tumors, as a hub of IC-mediated signaling within plaques. Additionally, we show that type 2 diabetes and lipid-lowering therapies alter immune cell interactions through PD-1, CTLA4, LAG3 and other IC targets in clinical development, impacting plaque inflammation. This comprehensive map of the IC interactome in healthy and cardiometabolic disease states provides a framework for understanding the potential adverse and beneficial impacts of approved and investigational ICIs on atherosclerosis, setting the stage for designing ICI strategies that minimize cardiovascular disease risk in cancer survivors.

Calcific aortic valve disease (CAVD) is a widely prevalent heart disorder in need of pharmacological interventions. Calcified areas in aortic valves often contain amyloid fibrils that promote calcification in vitro. This opinion paper suggests that amyloid contributes to CAVD development; amyloid-assisted nucleation can accelerate hydroxyapatite deposition onto collagen matrix. Notably, acidic arrays in amyloid match calcium-calcium spacing in the amorphous hydroxyapatite precursor, while oscillating hemodynamic perturbations promote amyloid deposition in the valve. Lipoprotein(a), a genetic risk factor for CAVD, augments calcification via several mechanisms, wherein hydrolysis of oxidized phospholipids (oxPLs) by Lp(a)-associated enzymes helps generate orthophosphate, and apolipoprotein(a) blocks plasmin-induced fibril degradation. Current studies of amyloid-calcium-collagen interactions in solution and in fibrillar complexes allow deeper insight into the role of amyloid in calcification.

TOPIC IMPORTANCE/UNASSIGNED:Chest CT imaging holds a major role in the diagnosis of lung diseases, many of which affect the peribronchovascular region. Identification and categorization of peribronchovascular abnormalities on CT imaging can assist in formulating a differential diagnosis and directing further diagnostic evaluation. REVIEW FINDINGS/RESULTS:The peribronchovascular region of the lung encompasses the pulmonary arteries, airways, and lung interstitium. Understanding disease processes associated with structures of the peribronchovascular region and their appearances on CT imaging aids in prompt diagnosis. This article reviews current knowledge in anatomic and pathologic features of the lung interstitium composed of intercommunicating prelymphatic spaces, lymphatics, collagen bundles, lymph nodes, and bronchial arteries; diffuse lung diseases that present in a peribronchovascular distribution; and an approach to classifying diseases according to patterns of imaging presentations. Lung peribronchovascular diseases can appear on CT imaging as diffuse thickening, fibrosis, masses or masslike consolidation, ground-glass or air space consolidation, and cysts, acknowledging that some diseases may have multiple presentations. SUMMARY/CONCLUSIONS:A category approach to peribronchovascular diseases on CT imaging can be integrated with clinical features as part of a multidisciplinary approach for disease diagnosis.

Cancer diagnosis and management depend upon the extraction of complex information from microscopy images by pathologists, which requires time-consuming expert interpretation prone to human bias. Supervised deep learning approaches have proven powerful, but are inherently limited by the cost and quality of annotations used for training. Therefore, we present Histomorphological Phenotype Learning, a self-supervised methodology requiring no labels and operating via the automatic discovery of discriminatory features in image tiles. Tiles are grouped into morphologically similar clusters which constitute an atlas of histomorphological phenotypes (HP-Atlas), revealing trajectories from benign to malignant tissue via inflammatory and reactive phenotypes. These clusters have distinct features which can be identified using orthogonal methods, linking histologic, molecular and clinical phenotypes. Applied to lung cancer, we show that they align closely with patient survival, with histopathologically recognised tumor types and growth patterns, and with transcriptomic measures of immunophenotype. These properties are maintained in a multi-cancer study.

In a previous study, heart xenografts from 10-gene-edited pigs transplanted into two human decedents did not show evidence of acute-onset cellular- or antibody-mediated rejection. Here, to better understand the detailed molecular landscape following xenotransplantation, we carried out bulk and single-cell transcriptomics, lipidomics, proteomics and metabolomics on blood samples obtained from the transplanted decedents every 6 h, as well as histological and transcriptomic tissue profiling. We observed substantial early immune responses in peripheral blood mononuclear cells and xenograft tissue obtained from decedent 1 (male), associated with downstream T cell and natural killer cell activity. Longitudinal analyses indicated the presence of ischemia reperfusion injury, exacerbated by inadequate immunosuppression of T cells, consistent with previous findings of perioperative cardiac xenograft dysfunction in pig-to-nonhuman primate studies. Moreover, at 42 h after transplantation, substantial alterations in cellular metabolism and liver-damage pathways occurred, correlating with profound organ-wide physiological dysfunction. By contrast, relatively minor changes in RNA, protein, lipid and metabolism profiles were observed in decedent 2 (female) as compared to decedent 1. Overall, these multi-omics analyses delineate distinct responses to cardiac xenotransplantation in the two human decedents and reveal new insights into early molecular and immune responses after xenotransplantation. These findings may aid in the development of targeted therapeutic approaches to limit ischemia reperfusion injury-related phenotypes and improve outcomes.