Citation: La Manna, M.P.; Di Liberto, D.; Lo Pizzo, M.; Mohammadnezhad, L.; Shekarkar Azgomi, M.; Salamone, V.; Cancila, V.; Vacca, D.; Dieli, C.; Maugeri, R.; et al. The Abundance of Tumor-Infiltrating CD8 + Tissue Resident Memory T Lymphocytes Correlates with Patient Survival in Glioblastoma. Biomedicines 2022, 10, 2454. https://doi.org/10.3390/ biomedicines10102454 Academic Editors: Kyuho Kang and Sungho Park Received: 9 August 2022 Accepted: 23 September 2022 Published: 1 October 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). biomedicines Article The Abundance of Tumor-Infiltrating CD8 + Tissue Resident Memory T Lymphocytes Correlates with Patient Survival in Glioblastoma Marco Pio La Manna 1,2 , Diana Di Liberto 2 , Marianna Lo Pizzo 1,3 , Leila Mohammadnezhad 1,3 , Mojtaba Shekarkar Azgomi 1,3 , Vincenzo Salamone 1,2 , Valeria Cancila 4 , Davide Vacca 4 , Costanza Dieli 1 , Rosario Maugeri 2,5 , Lara Brunasso 2,5 , Domenico Gerardo Iacopino 2,5 , Francesco Dieli 1,2 and Nadia Caccamo 1,2, * 1 Central Laboratory of Advanced Diagnosis and Biomedical Research (CLADIBIOR), University of Palermo, 90129 Palermo, Italy 2 Department of Biomedicine Neurosciences and Advanced Diagnostics, School of Medicine, University of Palermo, 90127 Palermo, Italy 3 Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties, University of Palermo, 90129 Palermo, Italy 4 Tumor Immunology Unit, Department of Health Sciences, University of Palermo, 90127 Palermo, Italy 5 Neurosurgical Clinic, AOUP “Paolo Giaccone”, Post Graduate Residency Program in Neurologic Surgery, 90127 Palermo, Italy * Correspondence: nadia.caccamo@unipa.it Abstract: Glial tumors alone account for 40% of all CNS tumors and present a low survival rate. The tumor microenvironment is a critical regulator of tumor progression and therapeutic effectiveness in glioma. Growing evidence from numerous studies of human solid tumor-infiltrating CD8 + T cells indicates that tissue-resident memory T cells (TRM) represent a substantial subpopulation of tumor- infiltrating lymphocytes (TILs). Although it is reported that some types of cancer patients with high immune infiltration tend to have better outcomes than patients with low immune infiltration, it seems this does not happen in gliomas. This study aimed to characterize TRMs cells in the glioma tumor microenvironment to identify their potential predictive and prognostic role and the possible therapeutic applications. Fluorescence activated cell sorting (FACS) analysis and immunofluorescence staining highlighted a statistically significant increase in CD8 + TRM cells (CD103 + and CD69 + CD8 + T cells) in gliomas compared to control samples (meningioma). In-silico analysis of a dataset of n = 153 stage IV glioma patients confirmed our data. Moreover, the gene expression analysis showed an increase in the expression of TRM-related genes in tumor tissues compared to normal tissues. This analysis also highlighted the positive correlation between genes associated with CD8 + TRM and TILs, indicating that CD8 + TRMs cells are present among the infiltrating T cells. Finally, high expression of Integrin subunit alpha E (ITGAE), the gene coding for the integrin CD103, and high CD8 + TILs abundance were associated with more prolonged survival, whereas high ITGAE expression but low CD8 + TILs abundance were associated with lower survival. Keywords: glioblastoma; tissue resident memory cells; CD8 + lymphocytes; tumor microenvironment 1. Introduction Gliomas define a remarkably heterogeneous group of cancers of the central nervous system originating from the glia cells. In 2016, a new WHO classification system was introduced based on the integration between morphological aspects and tumor molecular alterations, thus providing phenotypic and genotypic parameters that provide diagnostic process objectivity [1,2]. This classification system includes five main categories of adult dif- fuse glioma: glioblastoma, IDH-wild type; glioblastoma, IDH-mutant; diffuse or anaplastic Biomedicines 2022, 10, 2454. https://doi.org/10.3390/biomedicines10102454 https://www.mdpi.com/journal/biomedicines