Browsing by Author "Bell, W. Robert"

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    Invasive Fungal Infections of the Head and Neck: A Tertiary Hospital Experience
    (MDPI, 2024-06-23) Hou, Tieying; Bell, W. Robert; Mesa, Hector; Pathology and Laboratory Medicine, School of Medicine
    From the existing millions of fungal species, only a few cause disease. In this study, we investigated invasive fungal infections in the head and neck (H&N) over a 19-year period (2005 to 2024) at a large academic healthcare system. Among the 413 documented fungal H&N infections, 336 were noninvasive, and 77 were invasive. The highest incidence of invasive infections occurred in the sinonasal cavities, with a 15-fold difference compared to other sites. Most infections affected adults over 40 years old. The most common organisms were Mucorales (51%), hyaline molds (29%), and Candida (11%). Risk factors included malignancy, transplant, diabetes, and illicit drug use. Mortality was high in patients with malignancy and/or transplant. Infections affecting the mandible were usually a complication of osteoradionecrosis and were associated with the coinfection of Candida and Actinomyces. At other sites, infections were rare and were usually the result of penetrating injuries or immunosuppression. Treatment typically involved a combination of antifungals and surgical procedures.
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    VISTA Emerges as a Promising Target against Immune Evasion Mechanisms in Medulloblastoma
    (MDPI, 2024-07-24) Muñoz Perez, Natalia; Pensabene, Juliana M.; Galbo, Phillip M., Jr.; Sadeghipour, Negar; Xiu, Joanne; Moziak, Kirsten; Yazejian, Rita M.; Welch, Rachel L.; Bell, W. Robert; Sengupta, Soma; Aulakh, Sonikpreet; Eberhart, Charles G.; Loeb, David M.; Eskandar, Emad; Zheng, Deyou; Zang, Xingxing; Martin, Allison M.; Pathology and Laboratory Medicine, School of Medicine
    Background: Relapsed medulloblastoma (MB) poses a significant therapeutic challenge due to its highly immunosuppressive tumor microenvironment. Immune checkpoint inhibitors (ICIs) have struggled to mitigate this challenge, largely due to low T-cell infiltration and minimal PD-L1 expression. Identifying the mechanisms driving low T-cell infiltration is crucial for developing more effective immunotherapies. Methods: We utilize a syngeneic mouse model to investigate the tumor immune microenvironment of MB and compare our findings to transcriptomic and proteomic data from human MB. Results: Flow cytometry reveals a notable presence of CD45hi/CD11bhi macrophage-like and CD45int/CD11bint microglia-like tumor-associated macrophages (TAMs), alongside regulatory T-cells (Tregs), expressing high levels of the inhibitory checkpoint molecule VISTA. Compared to sham control mice, the CD45hi/CD11bhi compartment significantly expands in tumor-bearing mice and exhibits a myeloid-specific signature composed of VISTA, CD80, PD-L1, CTLA-4, MHCII, CD40, and CD68. These findings are corroborated by proteomic and transcriptomic analyses of human MB samples. Immunohistochemistry highlights an abundance of VISTA-expressing myeloid cells clustering at the tumor-cerebellar border, while T-cells are scarce and express FOXP3. Additionally, tumor cells exhibit immunosuppressive properties, inhibiting CD4 T-cell proliferation in vitro. Identification of VISTA's binding partner, VSIG8, on tumor cells, and its correlation with increased VISTA expression in human transcriptomic analyses suggests a potential therapeutic target. Conclusions: This study underscores the multifaceted mechanisms of immune evasion in MB and highlights the therapeutic potential of targeting the VISTA-VSIG axis to enhance anti-tumor responses.