Cellular and molecular regulation of the programmed death-1/programmed death ligand system and its role in multiple sclerosis and other autoimmune diseases.

Programmed Cell Death 1 (PD-1) receptor and its ligands (PD-Ls) are essential to maintain peripheral immune tolerance and to avoid tissue damage. Consequently, altered gene or protein expression of this system of co-inhibitory molecules has been involved in the development of cancer and autoimmunity. Substantial progress has been achieved in the study of the PD-1/PD-Ls system in terms of regulatory mechanisms and therapy. However, the role of the PD-1/PD-Ls pathway in neuroinflammation has been less explored despite being a potential target of treatment for neurodegenerative diseases. Multiple Sclerosis (MS) is the most prevalent, chronic, inflammatory, and autoimmune disease of the central nervous system that leads to demyelination and axonal damage in young adults. Recent studies have highlighted the key role of the PD-1/PD-Ls pathway in inducing a neuroprotective response and restraining T cell activation and neurodegeneration in MS. In this review, we outline the molecular and cellular mechanisms regulating gene expression, protein synthesis and traffic of PD-1/PD-Ls as well as relevant processes that control PD-1/PD-Ls engagement in the immunological synapse between antigen-presenting cells and T cells. Also, we highlight the most recent findings regarding the role of the PD-1/PD-Ls pathway in MS and its murine model, experimental autoimmune encephalomyelitis (EAE), including the contribution of PD-1 expressing follicular helper T (TFH) cells in the pathogenesis of these diseases. In addition, we compare and contrast results found in MS and EAE with evidence reported in other autoimmune diseases and their experimental models, and review PD-1/PD-Ls-targeting therapeutic approaches.

Efectos adversos inmunomediados por inhibidores de PD-1 / PD-1 inhibitors immune-mediated side effects

Los anticuerpos monoclonales que inhiben los puntos de control PD-1 y CTLA-4 se usan actualmente en el tratamiento del melanoma y cáncer metastásico de pulmón de células no pequeñas, entre otros. Se refiere el caso de una paciente con cáncer de pulmón en tratamiento con pembrolizumab. La paciente se presentó con edema facial y parálisis facial periférica. En el laboratorio se observó la hormona tirotrofina (TSH) elevada y se llegó al diagnóstico de hipotiroidismo por pembrolizumab. Inició tratamiento con levotiroxina con mejoría clínica. Se presenta este caso por el importante papel del dermatólogo en el manejo multidisciplinario del paciente oncológico. (AU)

Monoclonal antibodies that inhibit PD-1 and CTLA-4 control points are currently used in the treatment of melanoma and metastatic non-small cell lung cancer, among others. The case of a patient, with lung cancer being treated with Pembrolizumab. The patient was presented with facial edema and peripheral facial paralysis and in the laboratory the elevated hormone Tyrotrophin (TSH) was observed, the diagnosis of pembrolizumab hypothyroidism was reached. She started treatment with levothyroxine with clinical improvement. This case is presented by the important role of the dermatologist in the multidisciplinary management of the cancer patient. (AU)

PD-1 Expression in HIV-Specific CD8+ T cells Before Antiretroviral Therapy Is Associated With HIV Persistence.

BACKGROUND: The persistence of latently infected T cells remains the principal barrier to HIV cure. Understanding how the early immune responses shape persistence of HIV on antiretroviral therapy (ART) will be fundamental for potential eradication. Here, we aimed to determine the relationship between CD8 T-cell function and phenotype before therapy and HIV persistence on ART. METHODS: Blood samples from 29 individuals enrolled during primary HIV infection (at baseline and every 3 months up to 2 years post-ART initiation) were obtained. HIV-specific T-cell function and expression of the activation markers were evaluated before ART by flow cytometry. Cell-associated HIV DNA and unspliced (US)-RNA were quantified in purified CD4 T cells by real-time polymerase chain reaction. Data were analyzed using nonparametric statistics. RESULTS: Elevated immune activation, dominance of monofunctional CD8 T cells, and skewed distribution of memory profile were observed before ART. After ART initiation, HIV DNA and US-RNA levels rapidly diminished, reaching a plateau by 30 weeks after ART. The proportion of baseline HIV-specific effector memory and terminal effector CD8 T cells directly correlated with HIV DNA levels at 1 year after ART. A strong positive correlation was observed between the proportion of bulk and HIV-specific PD-1 CD8 T cells measured before ART and HIV DNA at 1 year after ART. CONCLUSIONS: A higher proportion of terminally differentiated CD8 T cells and increased PD1 expression were associated with HIV persistence on ART after treatment of primary infection. Thus, the quality of the early CD8 T-cell immune response may serve as a predictor of HIV persistence on ART.