PSGL-1: a novel immune checkpoint driving T-cell dysfunction in obstructive sleep apnea

Two-sample bi-directional causality between two traits with some invalid IVs in both directions using GWAS summary statistics

Mendelian randomization (MR) is a widely used method for assessing causal relationships between risk factors and outcomes using genetic variants as instrumental variables (IVs). While traditional MR assumes uni-directional causality, bi-directional MR aims to identify the true causal direction. In uni-directional MR, invalid IVs due to pleiotropy can violate assumptions and introduce biases. In bi-directional MR, traditional MR can be performed separately for each direction, but the presence of invalid IVs poses even greater challenges. We introduce a new bi-directional MR method incorporating stepwise selection (Bidir-SW) designed to address these challenges. Our approach leverages public genome-wide association study (GWAS) datasets for two traits and uses model selection criteria to identify invalid IVs iteratively by stepwise selection. This method accounts for potential bi-directional causality in the presence of common invalid IVs for both directions, even if only GWAS summary statistics are provided. Through simulation studies, we demonstrate that our method outperforms traditional MR techniques, such as MR-Egger and inverse-variance weighted (IVW), with uncorrelated SNPs. We also provide simulations to compare our approach with existing transcriptome-wide association study (TWAS) to show its effectiveness. Finally, we apply the proposed method to genetic traits such as CRP levels and BMI to explore possible bi-directional relationships among these traits. We also used the proposed method to discover causal protein biomarkers. Our findings suggest that the Bidir-SW approach is a powerful tool for bi-directional MR or TWAS, which can provide a valuable framework for future genetic epidemiology studies.

Revealing the mechanisms and therapeutic potential of immune checkpoint proteins across diverse protein families

Host immune responses to antigens are tightly regulated through the activation and inhibition of synergistic signaling networks that maintain homeostasis. Stimulatory checkpoint molecules initiate attacks on infected or tumor cells, while inhibitory molecules halt the immune response to prevent overreaction and self-injury. Multiple immune checkpoint proteins are grouped into families based on common structural domains or origins, yet the variability within and between these families remains largely unexplored. In this review, we discuss the current understanding of the mechanisms underlying the co-suppressive functions of CTLA-4, PD-1, and other prominent immune checkpoint pathways. Additionally, we examine the IgSF, PVR, TIM, SIRP, and TNF families, including key members such as TIGIT, LAG-3, VISTA, TIM-3, SIRPα, and OX40. We also highlight the unique dual role of VISTA and SIRPα in modulating immune responses under specific conditions, and explore potential immunotherapeutic pathways tailored to the distinct characteristics of different immune checkpoint proteins. These insights into the unique advantages of checkpoint proteins provide new directions for drug discovery, emphasizing that emerging immune checkpoint molecules could serve as targets for novel therapies in cancer, autoimmune diseases, infectious diseases, and transplant rejection.

Identifying and validating immunological biomarkers in obstructive sleep apnea through bioinformatics analysis

Obstructive sleep apnea (OSA) is a prevalent sleep disorder characterized by disrupted breathing patterns and dysfunctions in multiple organ systems. Although studies support a close correlation between OSA and immune function, the broader implications and specific manifestations remain unclear. Therefore, it is pressingly needed to identify potential immune-related markers and elucidate underlying immunological mechanisms of OSA. OSA-related datasets (GSE38792) and immune-related genes were downloaded from the GEO and ImmPort databases and intersected to obtain differentially expressed immune-related genes (DEIRGs). GO, KEGG, and GSEA were employed to explore the biological functions of DEIRGs. Immune cells and immune regulation were analyzed by CIBERSORT. The ROC curve was constructed to assess the accuracy of each DEIRG. The co-regulatory networks of transcription factors, microRNAs, and drugs were built using the NetworkAnalyst database and visualized by Cytoscape. The levels of DEIRGs in clinical samples were validated by RT-qPCR. GO, KEGG, and GSEA revealed that DEGs were mainly enriched in negative regulation of immune response and antigen processing and presentation in OSA. IL33, IL10RB, ANGPTL1, EIF2AK2, SEM1, IFNA16, SLC40A1, FCER1G, IL1R1, TNFRSF17, and ERAP2 were identified as DEIRGs among 175 differentially expressed genes in OSA. Memory B cells, mast cells resting, and dendritic cells resting were the predominant immune cells related to DEIRGs. The co-regulatory network contained 128 miRNAs, 40 transcription factors, and 172 drugs/compounds. Finally, IL33, EIF2AK2, IL10RB, and ANGPTL1 were also upregulated in clinical OSA samples. The present study identified potential immune-related biomarkers and systematically elucidated underlying immunological mechanisms of OSA. These findings provide novel insights into the diagnosis, mechanism research, and management strategies for future studies.

Short sleep time has a greater impact on the gut microbiota of female

BACKGROUND/OBJECTIVE

Short sleep duration (SSD) affects people's health in multiple ways. This study attempted to explore the effect of SSD on the gut microbiota.

METHODS

In the American Gut Project Database, 361 individuals (without troubled by disease recently) with less than 6 h of sleep per day were obtained and matched with normal sleep time individuals according to gender, age, and BMI. Furthermore, the raw data of 16s rRNA in feces were downloaded and analyzed using QIIME2, and STAMP was used for data statistics. PICRUST2 was used for predicting the alteration of microbial function.

RESULTS

The SSD did not affect the microbial α-diversity. SSD increased the abundance of the phylum Verrucomicrobia and the families Rikenellaceae, Verrucomicrobiaceae, and S24-7, and decrased the Coriobacteriaceae. Moreover, PICRUST2 predicted that SSD affected 15 metabolic pathways. Subgroup analyses showed that SSD had more significant effects on the microbiota in normal-weight females.

CONCLUSION

SSD substantially modifies the abundance of specific gut microbiota taxa, exerting a pronounced influence particularly on females, highlighting the need for further investigation into the bidirectional relationship between sleep patterns and gut microbiota.

Dysregulation in CD39/CD73 Axis May Trigger the Upsurge of the Immune Suppressive Agent Adenosine in OSA Patients

INTRODUCTION

Although higher incidence of cancer represents a major burden for obstructive sleep apnea (OSA) patients, the molecular pathways driving this association are not completely understood. Interestingly, adenosinergic signaling has emerged as a powerful immune checkpoint driving tumor development and progression.

METHODS

Here, we explored the expression of the adenosinergic ecto-enzymes CD39 and CD73 in T-lymphocytes of OSA patients without any evidence of cancer, as well as their soluble forms in plasma (sCD39 and sCD73), along with adenosine. In addition, we explored the role of intermittent hypoxia (IH) in this context by in vitro models.

RESULTS

Our results showed that CD39 is upregulated while CD73 is downregulated in OSA T-cells' membrane. Moreover, our findings suggest that IH, through HIF-1, mediates the upregulation of both CD39 and CD73; and that CD73 downregulation could be mediated by a higher release of sCD73 by OSA T-lymphocytes. Importantly, we found that both sCD39 and sCD73 are upregulated in OSA plasma, suggesting T-lymphocytes as a potential source for plasmatic sCD73. Finally, our data propose the alterations in CD39/CD73 axis could underlie the upsurge of adenosine levels in the plasma of OSA patients.

CONCLUSION

Our study reveals a hypoxia-mediated alteration of the CD39/CD73 axis in OSA patients, which could trigger ADO upregulation, thus potentially contributing to the immune suppressive environment and ultimately facilitating tumor development and progression. Therefore, our data highlights the need for new longitudinal studies evaluating CD39 and/or CD73 as potential cancer-risk prognostic biomarkers in OSA patients.