Unveiling altered CD8 T-cell metabolism and homeostatic proliferation behind a low CD4/CD8 ratio in ART-suppressed HIV individuals with normal CD4 recovery

Vanesa Garrido-Rodríguez¹Angel Bulnes-Ramos¹Israel Olivas-Martínez¹María Del Mar Pozo-Balado¹Francisco Tejerina-Picado^2,3Félix Gutiérrez^4,5Cristina Marco-Sánchez⁶Juan Tiraboschi⁷Antonia Castillo-Navarro⁸Enrique Bernal Morell⁹Maria C Garcia-Guerrero¹⁰Maria Carmen Puertas¹⁰Joaquim Peraire^11,12,13Anna Rull^11,12,13Javier Martinez-Picado^10,14,15Yolanda María Pacheco^1,16*

• ¹Institute of Biomedicine of Seville, Spanish National Research Council (CSIC), Seville, Spain
• ²Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Madrid, Spain
• ³Gregorio Marañón Hospital, Madrid, Madrid, Spain
• ⁴Hospital General Universitario de Elche, Elche, Spain
• ⁵Universidad Miguel Herrnández, Elche, Spain
• ⁶National Centre of Epidemiology, Carlos III Health Institute (ISCIII), Madrid, Madrid, Spain
• ⁷Bellvitge University Hospital, Barcelona, Balearic Islands, Spain
• ⁸Virgen de la Arrixaca University Hospital, Murcia, Murcia, Spain
• ⁹Hospital Reina Sofía de Murcia, Murcia, Murcia, Spain
• ¹⁰IrsiCaixa, Barcelona, Catalonia, Spain
• ¹¹Joan XXIII University Hospital of Tarragona, Tarragona, Catalonia, Spain
• ¹²University of Rovira i Virgili, Tarragona, Catalonia, Spain
• ¹³Pere Virgili Health Research Institute (IISPV), Tarragona, Catalonia, Spain
• ¹⁴University of Vic - Central University of Catalonia, Barcelona, Catalonia, Spain
• ¹⁵Catalan Institution for Research and Advanced Studies (ICREA), Barcelona, Catalonia, Spain
• ¹⁶Universidad de Loyola, Sevilla, Spain

Background. People living with chronic HIV (PLWH) show immune dysfunction, despite viral suppression and normal CD4-recovery, particularly those with low CD4/CD8-ratio. Subjacent cellular alterations of such reliable marker of clinical progression remain elusive. Methods. Categorization by CD4/CD8-ratio after three-years therapy (R<0.8/R>1.2, n=28/n=24) and post-hoc reclassification by nadir-CD4 (N≤350/N>350) were performed in PLWH achieving viral suppression and CD4≥500. CD4 T-cell-associated viral reservoir, as well as metabolism-related gene expression, glucose uptake ability, relative telomere length (RTL) and thymic output for CD4 and CD8 T-cells were determined. Results. Patients with CD4/CD8 ratio <0.8 exhibited reduced CD8 T-cell glucose uptake ability after stimulation (p=0.007), and trends to shorter RTL (p=0.093) and to larger CD4-associated viral reservoir (p=0.068) than R>1.2. Differently, patients with nadir ≤350 exhibited altered CD4 and CD8 T-cell expression of metabolism-related genes, although no differences in glucose uptake ability, and shorter RTL in both cell-subsets, but similar viral reservoir than patients with nadir >350. Remarkably, viral reservoir and both CD4 or CD8 thymic output showed inverse associations (r=-0.623, p=0.01 and r=-0.661, p=0.038, respectively). Conclusion. A low CD4/CD8-ratio in chronic PLWH stands on larger viral reservoir in CD4 T-cells and metabolic alterations in CD8 T-cells, probably related to its exhaustion and compromised effector functionality, and thymic output could contribute to such alterations. Patients with lower nadir-CD4, showed a resting-like CD4 phenotype and a metabolically active CD8 subset, without further viral reservoir extension. Persistence of low CD4/CD8 ratio and low nadir-CD4 counts seem to rely on different immune damage.