The Potential Role of Toxoplasma Gondii Infection in Breast Cancer Through Affecting Programmed Death-1 Genes

Background: This study aimed to evaluate the possible effects of Toxoplasma gondii infection on breast cancer through affecting the serum and expression gene level of programmed death-1 (PD-1) and programmed death-ligand 1 (PD-L1) in breast cancer patients from Thi-qar province, Iraq. Methods: This case-control study was involved 150 patients suffering from breast cancer (BC) who were referring to general hospitals of Thi-Qar province between July to September 2023 and 150 healthy patients (non-BC). Enzyme-linked immunosorbent test (ELISA) kit was used to evaluate the anti-Toxoplasma IgG and the serum level of PD-1 and PDL-1. Furthermore, the expression level of PD-1 and PDL-1 was measured through Real-time PCR. Results: Among 150 breast cancer patients, 71 patients (47.3%) and 25 (16.6%) of healthy subjects exhibited seropositivity for anti-T. gondii IgG antibodies, resepectively. We found that the serum level and the gene expression level of PD-1 and PDL-1 were significantly higher among BC patients seropositive for T. gondii compared with BC patients who were seronegative for T. gondii antibodies (p<0.05). Conclusion: These results indicated that T. gondii may play a role in the occurrence and even progression of cancer probably by elevating levels of PD-1 and PDL-1 genes. However, further studies are required to confirm these findings.