Dynamics of Plasmodium berghei NK-65 parasitaemia and CD3+CD4+CD25+Fox-p3+ T-regulatory cells in experimentally induced malaria during early, mid, and late-pregnancy in BALB/c mice.

ABSTRACT

Introduction: Malaria in pregnancy causes a dual brunt on the mother as well as the foetus. Upregulation of T-regulatory cells (Tregs) during pregnancy allows tolerance towards the growing foetus, their suppression predisposes the mother to infections. This study analyzed the levels of CD3+CD4+CD25+Fox-p3+ Tregs, parasitaemia, maternal and foetal outcomes in BALB/c mice infected with P. berghei NK65 during early-, mid-, and late-pregnancy. Methodology: Total of 114 mice, non-pregnant non-infected (n = 6), non-pregnant infected (n = 12), pregnant non-infected (n = 48) and pregnant infected (n = 48) were included in the study. Infected groups were inoculated intra-peritoneally with 1 × 106 P. berghei infected RBCs during early-, mid-, and late- pregnancy (D6, D10, and D14 respectively). Six mice from each stage were sacrificed on the 5th and 7th day post-infection (DPI) to evaluate parasitaemia (staining) and Tregs from splenocytes (by flow cytometry). Results: The parasitaemia was significantly higher among early pregnancy infected mice (≥ 70%) than mid-pregnancy infected (40-70%), late pregnancy infected (50-65%), and non-pregnant infected mice (≤ 50%) (p < 0.05). The level of Tregs was significantly higher among non-pregnant infected mice as compared to non-pregnant non-infected mice (%Tregs 0.86 vs. 0.44). Among pregnant mice, the levels of Tregs in infected mice were lower than in non-infected mice during all stages of pregnancy. None of the mice infected during early- and mid-pregnancy survived at 6DPI and 7DPI, respectively, and those infected during late-pregnancy delivered premature pups. Conclusion: In contrast to non-pregnant mice, the levels of Tregs among pregnant mice decrease when malaria infection is acquired thereby leading to adverse pregnancy outcomes. Supplementary Information The online version contains supplementary material available at 10.1007/s12088-023-01089-2.