Regulation of PD-L1 Expression by Nuclear Receptors

PD-L1 gene variants as predictors of recurrent pregnancy loss: A case-control study among Kazakh women in Central and West Kazakhstan

Emerging evidence implicates immune dysfunction in maintaining maternal-fetal tolerance, particularly the programmed death-ligand 1 (PD-L1) pathway. The association between PD-L1 gene variants and recurrent pregnancy loss (RPL) in women from Central and West Kazakhstan was investigated, and correlations between PD-L1 genotypes and demographic or clinical features were explored. This case-control study included 197 women with RPL and 198 controls of ethnically Kazakh women. Genotyping of rs2297136, rs2297137, rs4143815, rs822336, and rs822337 PD-L1 variants was performed by real-time PCR. Demographic and clinical characteristics did not differ significantly between RPL cases and controls from Central and West Kazakhstan. Significant associations were found in the West Kazakhstan cohort for rs822336 (p = 0.02) and rs822337 (p = 0.004). The G/C genotype of rs822336 (OR = 2.33, 95 % CI = 1.04-5.26) and rs822337 (OR = 308, 95 % CI = 1.34-7.04) was associated with an increased risk of RPL in West Kazakhstan cohort. Haplotype analysis revealed a significant association of the GTGAG haplotype with RPL in West Kazakhstan (p = 0.018) but not in Central Kazakhstan subjects. Correlation analysis showed that rs822336 was positively correlated with age and BMI (p < 0.05) in Central Kazakhstan, while rs822337 was negatively correlated with live births in West Kazakhstan (p < 0.05). The findings underscore population-specific genetic influences on RPL risk, with notable significant associations between RPL and PD-L1 SNPs and GTGAG haplotype in the West Kazakhstan cohort but not in the Central Kazakhstan cohort. This highlights the contribution of genetic factors to RPL pathogenesis in different populations.

PD-L1 Expression in Receptor-Negative Breast Cancer Tissue

BACKGROUND

The high heterogeneity and pathogenetic diversity of breast cancer (BCa) indicate the need for further study of tumor cell biology in order to identify molecular biological markers associated with the aggressiveness of tumors with a negative receptor status. Among many factors that may be involved in the initiation and progression of this form of cancer, the study of the immune components of tumor microenvironment, in particular PD-L1, is considered promising.

AIM

To investigate the relationship between PD-L1 expression in tumor tissue and clinical and pathological characteristics of BCa, taking into account the status of steroid hormone receptors.

MATERIALS AND METHODS

In tumor tissue of 116 patients with stage I-II BCa, the mRNA levels of CD274 gene were determined using the real-time quantitative polymerase chain reaction. The expression of PD-L1 was studied by the immunohistochemical method.

RESULTS

The tissue of receptor-negative BCa was characterized by a significant decrease in the CD274 mRNA level against the background of the increased PD-L1 expression compared to neoplasms positive for the expression of steroid hormone receptors. An inverse correlation was found between PD-L1 at the protein level and the age of patients with receptor-negative BCa (r = -0.613, p = 0.00003). We showed that a characteristic feature of receptor-negative BCa in menopausal patients is the increased expression of PD-L1 both at the protein and mRNA levels (p = 0.005 and p = 0.046, respectively). The correlation of PD-L1 expression with metastatic lesions in regional lymph nodes (p = 0.050), tumor differentiation grade (p = 0.001), and the patient survival rate was revealed.

CONCLUSIONS

The obtained data indicated the expediency of using PD-L1 expression indicators for in-depth characterization of the tumor microenvironment of receptor-negative BCa, which will allow for the personalized correction of therapy regimens contributing to the improvement of the patients' quality of life.

A Critical Role of Intracellular PD-L1 in Promoting Ovarian Cancer Progression

Disrupting the interaction between tumor-cell surface PD-L1 and T cell membrane PD-1 can elicit durable clinical responses. However, only about 10% of ovarian cancer patients respond to PD-1/PD-L1 blockade. Here, we show that PD-L1 expression in ovarian cancer-patient tumors is predominantly intracellular. Notably, PARP inhibitor treatment highly increased intracellular PD-L1 accumulation in both ovarian cancer-patient tumor samples and cell lines. We investigated whether intracellular PD-L1 might play a critical role in ovarian cancer progression. Mutating the PD-L1 acetylation site in PEO1 and ID8Brca1-/- ovarian cancer cells significantly decreased PD-L1 levels and impaired colony formation, which was accompanied by cell cycle G2/M arrest and apoptosis induction. PEO1 and ID8Brca1-/- tumors with PD-L1 acetylation site mutation also exhibited significantly reduced growth in mice. Furthermore, targeting intracellular PD-L1 with a cell-penetrating antibody effectively decreased ovarian tumor-cell intracellular PD-L1 level and induced tumor-cell growth arrest and apoptosis, as well as enhanced DNA damage and STING activation, both in vitro and in vivo. In conclusion, we have shown the critical role of intracellular PD-L1 in ovarian cancer progression.

Programmed death receptor (PD-)1/PD-ligand (L)1 in urological cancers : the "all-around warrior" in immunotherapy

Programmed death receptor-1 (PD-1) and its ligand, programmed death ligand-1 (PD-L1) are essential molecules that are key in modulating immune responses. PD-L1 is constitutively expressed on various immune cells, epithelial cells, and cancer cells, where it functions as a co-stimulatory molecule capable of impairing T-cell mediated immune responses. Upon binding to PD-1 on activated T-cells, the PD-1/PD-L1 interaction triggers signaling pathways that can induce T-cell apoptosis or anergy, thereby facilitating the immune escape of tumors. In urological cancers, including bladder cancer (BCa), renal cell carcinoma (RCC), and prostate cancer (PCa), the upregulation of PD-L1 has been demonstrated. It is linked to poor prognosis and enhanced tumor immune evasion. Recent studies have highlighted the significant role of the PD-1/PD-L1 axis in the immune escape mechanisms of urological cancers. The interaction between PD-L1 and PD-1 on T-cells further contributes to immunosuppression by inhibiting T-cell activation and proliferation. Clinical applications of PD-1/PD-L1 checkpoint inhibitors have shown promising efficacy in treating advanced urological cancers, significantly improving patient outcomes. However, resistance to these therapies, either intrinsic or acquired, remains a significant challenge. This review aims to provide a comprehensive overview of the role of the PD-1/PD-L1 signaling pathway in urological cancers. We summarize the regulatory mechanism underlying PD-1 and PD-L1 expression and activity, including genetic, epigenetic, post-transcriptional, and post-translational modifications. Additionally, we discuss current clinical research on PD-1/PD-L1 inhibitors, their therapeutic potential, and the challenges associated with resistance. Understanding these mechanisms is crucial for developing new strategies to overcome therapeutic limitations and enhance the efficacy of cancer immunotherapy.

The opportunities and challenges of using PD-1/PD-L1 inhibitors for leukemia treatment

Leukemia poses a significant clinical challenge due to its swift onset, rapid progression, and treatment-related complications. Tumor immune evasion, facilitated by immune checkpoints like programmed death receptor 1/programmed death receptor ligand 1 (PD-1/PD-L1), plays a critical role in leukemia pathogenesis and progression. In this review, we summarized the research progress and therapeutic potential of PD-L1 in leukemia, focusing on targeted therapy and immunotherapy. Recent clinical trials have demonstrated promising outcomes with PD-L1 inhibitors, highlighting their role in enhancing treatment efficacy. This review discusses the implications of PD-L1 expression levels on treatment response and long-term survival rates in leukemia patients. Furthermore, we address the challenges and opportunities in immunotherapy, emphasizing the need for personalized approaches and combination therapies to optimize PD-L1 inhibition in leukemia management. Future research prospects include exploring novel treatment strategies and addressing immune-related adverse events to improve clinical outcomes in leukemia. Overall, this review provides valuable insights into the role of PD-L1 in leukemia and its potential as a therapeutic target in the evolving landscape of leukemia treatment.

Relationship of Low Vitamin B6 Status with Sarcopenia, Frailty, and Mortality: A Narrative Review

Marginal vitamin B6 (B6) deficiency is a widespread global concern. Inadequate B6 levels have been linked to an increased risk of age-related chronic diseases such as cardiovascular diseases and cancers. In recent years, the growing concern over sarcopenia (the age-related loss of muscle mass and strength) and frailty (a decline in physiological resilience and increased vulnerability associated with aging) is particularly relevant due to the emergence of super-aged societies in developed countries. Notably, among the thirty-one studies included in this review, twenty-five showed a significant association of B6 status with sarcopenia, frailty, and all-cause mortality in adults (p < 0.05), while six showed no association. Emerging studies have suggested novel mechanisms underlying this association. These mechanisms involve P2X7 receptor-mediated NLRP3 inflammasome signaling, AMPK signaling, PD-L1 signaling, and satellite cell-mediated myogenesis. Furthermore, the modulation of PLP-dependent enzymes due to B6 deficiency is associated with impaired metabolic processes, affecting energy utilization, imidazole peptide production, and hydrogen sulfide production, as well as the kynurenine pathway, all of which play vital roles in skeletal muscle health and pathophysiology. This narrative review provides an up-to-date assessment of our current understanding of the potential role of nutritional B6 status in combating sarcopenia, frailty, and mortality.

The Role of Gut Microbiota-Derived Lithocholic Acid, Deoxycholic Acid and Their Derivatives on the Function and Differentiation of Immune Cells

A wide variety and large number of bacterial species live in the gut, forming the gut microbiota. Gut microbiota not only coexist harmoniously with their hosts, but they also induce significant effects on each other. The composition of the gut microbiota can be changed due to environmental factors such as diet and antibiotic intake. In contrast, alterations in the composition of the gut microbiota have been reported in a variety of diseases, including intestinal, allergic, and autoimmune diseases and cancer. The gut microbiota metabolize exogenous dietary components ingested from outside the body to produce short-chain fatty acids (SCFAs) and amino acid metabolites. Unlike SCFAs and amino acid metabolites, the source of bile acids (BAs) produced by the gut microbiota is endogenous BAs from the liver. The gut microbiota metabolize BAs to generate secondary bile acids, such as lithocholic acid (LCA), deoxycholic acid (DCA), and their derivatives, which have recently been shown to play important roles in immune cells. This review focuses on current knowledge of the role of LCA, DCA, and their derivatives on immune cells.