Evaluation of PDCD1 and LAG3 Gene Polymorphisms in Psoriasis Patients

Project no. 32590 · Status: Kapanmış (Yayın bekleniyor) · 2024

Summary

Psoriasis is a common autoimmune, systemic, and chronic inflammatory skin disease caused by both environmental and genetic factors. Although its pathogenesis has not been fully elucidated, it is thought to result from disturbances in both innate and adaptive immune responses. The main skin lesions of psoriasis are erythematous plaques with silvery scales, confirmed by histopathological or clinical diagnosis. However, lesion morphology and distribution vary greatly among patients and even within the same patient depending on disease stage. Therefore, psoriasis is classified into subtypes such as plaque, guttate, pustular, and erythrodermic according to lesion morphology, and as scalp, nail, palmoplantar, inverse, or genital psoriasis according to anatomical localization.The most commonly used method to assess disease severity is the Psoriasis Area and Severity Index (PASI), which evaluates erythema, scaling, and induration of lesions on the head, trunk, upper, and lower extremities. PASI scores range from 0 to 72, where <5 indicates mild, 5–10 moderate, and >10 severe disease.Single nucleotide polymorphisms (SNPs) are the most common form of genetic variation, involving substitution of a single base (A, T, G, or C) within the DNA sequence. SNPs are responsible for phenotypic differences between individuals and may be associated with disease susceptibility or treatment responses.The programmed cell death 1 (PDCD1) gene (Gene ID: 5133) is located on chromosome 2q37.3, consists of six exons, and encodes the 288-amino-acid precursor protein (268 amino acids in its mature form) responsible for the expression of the programmed death receptor 1 (PD-1). PD-1 is a transmembrane receptor that functions as an immune checkpoint molecule on peripheral T cells. By binding to its ligands, PD-L1 and PD-L2, PD-1 suppresses immune activation, maintaining tolerance to self-antigens. However, some malignant tumors evade immune surveillance by expressing PD-L1. Therefore, PD-1 and PD-L1 inhibitors have been widely used in cancer immunotherapy. Several case reports describe PD-1/PD-L1 inhibitors exacerbating preexisting psoriasis or inducing psoriasiform eruptions in previously healthy individuals.Bartosińska et al. demonstrated that PDCD1 gene expression is reduced in patients with psoriasis compared to healthy controls. Similarly, Shengyuan et al. reported that individuals carrying the guanine allele in the 3′ untranslated region (3′UTR) of PDCD1 had an increased risk of developing psoriasis in the Chinese population.The lymphocyte activation gene 3 (LAG-3) is located on the short arm of the chromosome and consists of eight exons. It encodes a 498-amino-acid transmembrane receptor that functions similarly to PD-1 and cytotoxic T-lymphocyte–associated antigen 4 (CTLA-4). The LAG-3 receptor, expressed on both CD4+ helper and CD8+ cytotoxic T cells, interacts with the T-cell receptor (TCR)-CD3 complex and binds to several ligands including MHC class II, fibrinogen-like protein 1 (FGL-1), and galectin-3 (Gal-3), thereby inhibiting TCR signaling and downregulating cytokine production.Previous studies have shown downregulation of LAG-3–expressing T cells in autoimmune diseases such as psoriatic arthritis, Hashimoto’s and Graves’ thyroiditis, multiple sclerosis (MS), and type 1 diabetes mellitus. Moreover, SNPs in the intronic region of LAG3 (rs1922452) have been linked to increased comorbidity in MS and a higher risk of Parkinson’s disease. Epidemiological studies also suggest a higher incidence and progression of MS and Parkinson’s disease in psoriasis patients, implying a potential shared immunogenetic background.This study aims to compare LAG3 and PDCD1 gene polymorphisms in patients with psoriasis and healthy individuals, investigating their associations with disease presence, severity, and clinical subtypes, thereby contributing to the understanding of psoriasis pathogenesis. To date, no published data have addressed the impact of LAG3 polymorphisms on psoriasis, and studies exploring PDCD1 variants remain limited.The study will include 115 psoriasis patients newly diagnosed or followed in the Dermatology Clinic and 65 healthy controls without psoriasis, for a total of 180 participants. After obtaining informed consent, demographic (age, sex) and clinical data (disease subtype, PASI score, treatments) will be collected.Peripheral blood samples will be obtained in EDTA tubes from all participants. Total DNA isolation will be performed using a standardized kit protocol involving proteinase K lysis, spin column purification, washing steps, and elution in water or buffer. Isolated DNA samples will then be analyzed using real-time PCR (RT-PCR) to detect LAG3 rs1922452 and PDCD1 rs10204525 polymorphisms. Specific primers will be used to amplify target regions, and reactions will be performed in a total volume of 25 µL containing 1× PCR buffer, 1.5 mM MgCl₂, 200 µM dNTPs, 0.2 µM primers, and 1 unit of Taq polymerase.PCR products will be analyzed using LightCycler 480 software under the melting temperature (Tm) calling mode, and melting curve genotyping will be performed to identify allelic variants for each sample. Statistical analysis will be conducted using SPSS software, with p<0.05 considered statistically significant.Data will be interpreted in light of existing literature to discuss the potential roles of PDCD1 and LAG3 polymorphisms in psoriasis susceptibility and severity, as well as their implications for clinical practice.The study, encompassing patient recruitment, blood sampling, DNA isolation, RT-PCR genotyping, and data analysis, is planned to be completed within an 18-month period.

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