Protective role of T regulatory (Treg) cells in systemic lupus erythematosus patients with nephritis

Aim: To assess the role of CD4+CD25+Foxp3+, CD4+CD25- Foxp3+, CD4+CD25+Foxp3- T cells and the fork head family transcription factor (Foxp3) gene polymorphism in systemic lupus erythematosus (SLE) and lupus nephritis (LN) patients. Patients and methods: The study comprised 40 SLE patients (including 38 females and 2 males) and 30 matched controls. SLE disease activity index (SLEDAI) was assessed. The percentage of expression of CD4, CD25 and Foxp3 on T cells was measured by flow cytometry. Foxp3 gene was genotyped using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results: The patients were 38 females and 2 males with a mean age of 30.3 +/- 8.9 years and disease duration of 7.4 +/- 5.7 years. Their mean SLEDAI was 7.5 +/- 6.7. Flow cytometry revealed 3 types of T cells; CD4 +CD25+Foxp3+, CD4+CD25- Foxp3+ and CD4+CD25+Foxp3-. No significant differences were found in the percentage of expression and absolute counts of CD4+CD25+Foxp3+, CD4+CD25- Foxp3+ and CD4 +CD25+Foxp3- T cells in patients and controls (p=0.26, p=0.22, p=0.32 respectively). CD4+CD25+Foxp3 +T cells were significantly lower in patients with LN compared to those without (p<0.001). CD4+CD25Foxp3+ T cells and Foxp3 (G/G) genotype were significantly associated with the grades of LN (p<0.001, p=0.003 respectively). The relationship between SLEDAI and the absolute counts of CD4+CD25+Foxp3+, CD4+CD25- Foxp3+ and CD4+CD25+Foxp3- T cells was insignificant (r=-0.04, p=0.78; r=0.05, p=0.76 and r=0.05, p=0.77 respectively). A significant difference in SLEDAI between patients expressing Foxp3 A/A genotype and those not was observed (p<0.01). Conclusion: CD4+CD25+Foxp3+, CD4+CD25- Foxp3+ and CD4+CD25+Foxp3- T cells are important regarding the pathogenesis of LN and could help assess the severity of renal involvement. (c) 2022 THE AUTHORS. Publishing services by ELSEVIER B.V. on behalf of The Egyptian Society of Rheumatic Diseases. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).