Alexandra-Elena Constantinescu

Exceptional longevity is a multifactorial phenomenon in which optimal immune system function plays an essential role. KIR receptors (Killer-cell Immunoglobulin-like Receptors), expressed on Natural Killer (NK) cells and on subpopulations of CD8+ T lymphocytes, represent key modula-tors of innate immunity. The extensive polymorphism of the KIR locus generates interindividual variability in immune surveillance capacity, with possible implications for aging. NK cells play a pivotal role in the immune response. During the ageing process, the activity and number of NK cells varies. The cytolytic activity of the natural killer cells is controlled by an array of activating and inhibitory cell surface receptors, including the KIRs.The present study aims to explore the frequency of KIR alleles in a cohort of 86 individuals in the 65-90 age bracket from Romania, providing inisghts into genetic diversity and potential implications in longevity. High-resolution KIR typing was performed using next-generation sequencing (NGS) technology, allowing for pre-cise identification of KIR alleles with a high degree of accuracy. The results reveal significant ge-netic diversity within the cohort, with prevalent alleles such as KIR2DL3*0020103, KIR2DL3*0020101, KIR2DS2*0010124, KIR2DS2*0010115 or KIR3DL1*0050101, potentially influencing disease susceptibility and longevity. The study reveals the genetic diversity of KIR alleles in elderly Romanians, highlighting prevalent alleles that could be linked to longevity and disease resistance. Further studies with larger number of samples are needed to confirm findings and uncover their implications for healthy aging and healthcare.

The human leukocyte antigen (HLA) system plays a crucial role in regulating the immune response and is significant in organ transplantation, disease association studies, and population genetics. But does it influence longevity? The present study aims to explore the frequency of HLA alleles in a cohort of 100 individuals in the 65–90 age bracket from Romania, providing insights into genetic diversity and potential implications in longevity. High-resolution HLA typing was performed using next-generation sequencing (NGS) technology, allowing for precise identification of HLA alleles with a high degree of accuracy. The results reveal significant genetic diversity within the cohort, with prevalent alleles such as HLA-A*02:01:01:01, HLA-B*08:01:01:01, and DRB1*01:01:01:01 potentially influencing disease susceptibility and longevity. The study reveals the genetic diversity of HLA alleles in elderly Romanians, highlighting prevalent alleles that could be linked to longevity and disease resistance. Different results from previous research are attributed to the high-resolution analysis and small cohort size. Further studies with larger samples are needed to confirm findings and uncover their implications for healthy aging and healthcare.

Multiple sclerosis (MS) is a chronic autoimmune disease characterized by the immune system attacking the central nervous system, leading to demyelination and neurodegeneration. This work investigates the relationship between specific human leukocyte antigen (HLA) polymorphisms and MS, aiming to reveal the immunogenetic background of this disease for more individualized management approaches. This study employed a case–control design, analyzing HLA allele frequencies in 179 MS patients and 200 control subjects using next-generation sequencing, The key findings indicate significant associations between several HLA Class I and II alleles and MS, including HLA-B*35:03:01:03, HLA-C*04:01:01:14, HLA-DRB1*15:01:01:26, and HLA-DQA1*05:05:01:02. These findings emphasize the critical role of HLA molecules in MS Romanian patients.

Background/Objectives: Tacrolimus is a key immunosuppressant in kidney transplantation, but its high interindividual pharmacokinetic variability complicates dosing. This study aimed to develop a population pharmacokinetic model and identify the factors explaining variability to optimize tacrolimus therapy in Romanian kidney transplant recipients. Methods: The study included 106 kidney transplant recipients treated at Fundeni Clinical Institute (2022–2024). Tacrolimus blood levels were measured using immunoassays, while gene polymorphisms of CYP3A4, CYP3A5, and ABCB1 were identified by real-time polymerase chain reaction. Results: Patients with CYP3A4*1/*1.001 impact clearance (RSE = 11.8%), while hematocrit was a significant covariate for intercompartmental clearance (RSE = 6.14%). Conclusions: Incorporating CYP3A4*1/*1.001 genotype and hematocrit into dosing strategies can improve therapeutic drug monitoring and personalize immunosuppressive therapy.

Human Leukocyte Antigen (HLA) genes are remarkable for their structural complexity and polymorphism. Located on chromosome 6 within the Major Histocompatibility Complex (MHC), these genes exhibit significant frequency variations across human populations and play a crucial role in immune responses, disease susceptibility, and transplant compatibility. This study aimed to assess the genetic profiles and HLA-A/HLA-B/HLA-C/HLA-DRB1 haplotype frequencies in a Romanian cohort. Whole venous blood samples were collected from 405 healthy, unrelated Romanian volunteers. Using next-generation sequencing (NGS), the study population was genotyped for HLA class I (HLA-A, HLA-B, and HLA-C) and class II (HLA-DRB1) loci. Haplotype frequencies were estimated using the expectation-maximization algorithm, addressing phase and allelic ambiguity. The Romanian cohort was compared with multiple populations sourced from the Allele Frequencies Net Database. The study identified 635 different HLA-A/HLA-B/HLA-C/HLA-DRB1 haplotypes. Among them, two haplotypes had frequencies close to 3%: HLA-A*01:01:01/HLA-B*08:01:01/HLA-C*07:01:01/HLA-DRB1*03:01:01, with a frequency of 3.33%, and HLA-A*02:01:01/HLA-B*18:01:01/HLA-C*17:01:01/HLA-DRB1*11:04:01, with a frequency of 2.84%. All other 633 haplotypes (approximately 99.7% of the total) had frequencies below 1%. The results of the current study underscore the extremely high diversity of HLA haplotypes in this population and the fact that even the most frequent haplotypes are relatively low in prevalence (each under 5% in this cohort). These findings and the great haplotypical diversity detected highlight the importance of NGS and high-resolution HLA typing in hematopoietic stem cell and solid organ transplantation, while also contributing to the better understanding of the area-specific population genetics resulting from historical regional dynamics. Further research with larger cohorts is necessary to validate these findings and expand upon their clinical implications.

HLA (Human Leukocyte Antigen) genes are a cornerstone of immunogenetics, having a significant impact on a wide range of biological processes and pathologies, from immune responses to the evolution of autoimmune and infectious diseases. Modern sequencing technologies, such as Next-Generation Sequencing (NGS), allow for detailed analysis of this complex system, providing unprecedented resolution. By integrating these advanced technologies, research in the HLA field opens new opportunities for personalized medicine, enabling early diagnosis, treatment of autoimmune diseases, transplantation, and immunotherapy. Furthermore, HLA sequencing plays a crucial role in vaccine development and innovative treatments, contributing to public health improvement and patient quality of life. In addition to its medical impact, HLA also plays an important role in anthropology, providing essential insights into human genetic diversity, population evolution, and adaptation to the environment, as well as interactions with pathogens. HLA studies help reconstruct human history by identifying migration routes and evolutionary mechanisms. To fully leverage the potential of HLA in research and clinical practice, bioinformatics and artificial intelligence methods are essential, enabling rapid analysis and interpretation of complex data. Technological advancements continue to transform the field, facilitating the development of new therapeutic strategies and high-precision diagnostics.

Next-generation sequencing (NGS) has completely revolutionized the analysis of HLA genes, offering superior resolution and the possibility of identifying previously unknown or rare alleles. NGS technology allows for the complete sequencing of the the HLA locus, the analysis of coding and non-coding regions, and a detailed characterization of haplotypes, with essential benefits in areas such as organ transplantation and in studies of autoimmune diseases. The chapter explores the applications of NGS in personalized medicine, including the identification of neoantigens for oncology immunotherapies and the development of vaccines adapted to the genetic diversity of the population. Bioinformatic and ethical challenges are also discussed. By reducing the limitations of traditional methods and opening up new horizons for research and clinical applications, NGS is redefining the standards in HLA typing and is making a significant contribution to the progress of precision medicine.

Tacrolimus (Tc) is an immunosuppressant used in transplant patients, but its therapeutic range is narrow, making precise dosing essential. This study investigates the association of three single nucleotide polymorphisms (SNPs) (ABCB1 3435C>T, 1236C>T, 2677G>T/A) with Tc levels over time to gain better insights into their role in personalized medicine. We conducted the study over four distinct periods: 1–14 days, 15–30 days, 31–60 days, and beyond 60 days post-transplantation. The analysis included allele, genotype, haplotype, and diplotype frequencies of the three SNPs concerning Tc blood levels. Statistical significance was determined, and false discovery rate (P_FDR) correction was applied where appropriate. Significant associations were found between the C (ABCB1 C1236T), A alleles (ABCB1 G2677T/A), the CAC haplotype and lower Tc levels. The CAC-TGT and TGT-TGT diplotypes significantly influence how patients metabolize the drug. The TGT haplotype and the AA genotype (ABCB1 G2677T/A) were associated with higher Tc levels, suggesting a long-term genetic influence. Genetic factors, specifically certain SNPs and diplotypes, significantly impact Tc blood levels, with their influence varying over time.

Chronic lymphocytic leukemia (CLL) is a distinct category of lymphoproliferative disorder characterized by the clonal expansion of mature B cells, followed by their accumulation in primary and secondary lymphoid organs. Cluster of differentiation (CD) markers such as CD79b, CD45, CD23, CD22 and CD81 serve as reliable prognostic indicators in CLL as well as the human leukocyte antigen (HLA) with its well-documented associations with various cancers. This study aims to investigate, for the first time, potential connections between HLA typing and CD marker expression in CLL. Although it is one of the most prevalent neoplasms, there is a need for biomarkers that can improve survival. This study included 66 CLL patients and 100 controls, with all samples analyzed using biochemical methods, flow cytometry, and cytomorphology. Next-generation sequencing was performed for HLA typing. The results indicate that several CD markers are statistically associated with different HLA alleles, specifically CD45 with HLA-C*07:01:01; CD79b with HLA-DPA1*02:01:02; CD23 with HLA-B*39:01:01; CD22 with HLA-B*49:01:01, HLA-C*07:01:01, HLA-DPB1*02:01:02, and HLA-DRB1*07:01:01; and CD81 with HLA-DPB1*04:02:01, HLA-DQA1*01:04:01, and HLA-DQB1*05:03:01. In conclusion, this research demonstrates significant statistical links between HLA genes and immunophenotypic markers in CLL patients, shedding new light on the immunological context of CLL.

Aging is an exceptionally complex process that depends on genetic, environmental, and lifestyle factors. Previous studies within the International HLA and Immunogenetics Workshop (IHIWS) component “Immunogenetics of Ageing” showed that longevity is associated with positive selection of HLA-DRB1*11- and DRB1*16-associated haplotypes, shown to be protective against diseases. Within the 18th IHIWS, we aimed to investigate the relevance of telomere length for successful aging and its association with classical HLAs. In total 957 individuals from Bulgaria, Turkey, Romania, and Poland in two age groups, elderly individuals (age 65–99 years) and ethnically matched young group (age 18–64 years), were investigated. The obtained results confirmed interpopulation differences in the distribution of HLA alleles, documented the lengths of telomeres in analyzed populations, and demonstrated significant associations of telomere length with aging as well as with the presence of some HLA class I or class II alleles. They suggest that telomere length assessment combined with HLA genotyping may help identify immunogenetic profiles associated with longevity. The associations between HLA and telomeres support the theory that HLA genes influence the aging process. However, further research is needed to clarify the biological basis of the observed relationships.