PD-L1 expression on peripheral T-cells and association with coronary heart disease patients: A protocol for systematic reviews and meta-analysis

BACKGROUND: As immune checkpoint pathways, programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) can be exploited by tumor cells to evade immuno-surveillance. Inflammation and immune processes play decisive roles in the occurrence and development of coronary heart disease (CHD). The low expression level of PD-1/ PD-L1 or anti-PD-1/PD-L1 therapy can accelerate the immune processes in CHD and aggravates disease based on numerous studies. However, the expression of PD-L1 and CHD still remains controversial to date. We conducted this meta-analysis to detect the value of PD-L1 expression on peripheral T-cells in CHD. METHODS: We will search PubMed, Embase, Web of Science, Google Scholar, Chinese National Knowledge Infrastructure, Chinese VIP Information, Wanfang Database, and Chinese Biomedical Literature Database for related published studies before February 2021. Two review authors will search and assess relevant studies independently. Case control studies and cohort studies will be included. The Revman 5.3 software was applied to carry out the meta-analysis for the included literature. RESULTS: The findings of this systematic review will be disseminated in a peer-reviewed publication and/or presented at relevant conferences. CONCLUSION: This study will provide a new theoretical basis for the immunological prevention and treatment of CHD. TRIAL REGISTRATION NUMBER: DOI 10.17605/OSF.IO/X3R52. ETHICS AND DISSEMINATION: Formal ethical approval is not required, as the data are not individualized.