Wuchereria bancrofti-infected individuals harbor distinct IL-10-producing regulatory B and T cell subsets which are affected by anti-filarial treatment

PLoS Negl Trop Dis. 2019 May 23;13(5):e0007436. doi: 10.1371/journal.pntd.0007436. eCollection 2019 May.

Abstract

Despite worldwide mass drug administration, it is estimated that 68 million individuals are still infected with lymphatic filariasis with 19 million hydrocele and 17 million lymphedema reported cases. Despite the staggering number of pathology cases, the majority of LF-infected individuals do not develop clinical symptoms and present a tightly regulated immune system characterized by higher frequencies of regulatory T cells (Treg), suppressed proliferation and Th2 cytokine responses accompanied with increased secretion of IL-10, TGF-β and infection-specific IgG4. Nevertheless, the filarial-induced modulation of the host`s immune system and especially the role of regulatory immune cells like regulatory B (Breg) and Treg during an ongoing LF infection remains unknown. Thus, we analysed Breg and Treg frequencies in peripheral blood from Ghanaian uninfected endemic normals (EN), lymphedema (LE), asymptomatic patent (CFA+MF+) and latent (CFA+MF-) W. bancrofti-infected individuals as well as individuals who were previously infected with W. bancrofti (PI) but had cleared the infection due to the administration of ivermectin (IVM) and albendazole (ALB). In summary, we observed that IL-10-producing CD19+CD24highCD38dhigh Breg were specifically increased in patently infected (CFA+MF+) individuals. In addition, CD19+CD24highCD5+CD1dhigh and CD19+CD5+CD1dhighIL-10+ Breg as well as CD4+CD127-FOXP3+ Treg frequencies were significantly increased in both W. bancrofti-infected cohorts (CFA+MF+ and CFA+MF-). Interestingly, the PI cohort presented frequency levels of all studied regulatory immune cell populations comparable with the EN group. In conclusion, the results from this study show that an ongoing W. bancrofti infection induces distinct Breg and Treg populations in peripheral blood from Ghanaian volunteers. Those regulatory immune cell populations might contribute to the regulated state of the host immune system and are probably important for the survival and fertility (microfilaria release) of the helminth.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Albendazole / administration & dosage
  • Animals
  • Anthelmintics / administration & dosage*
  • B-Lymphocytes, Regulatory / immunology*
  • Elephantiasis, Filarial / drug therapy*
  • Elephantiasis, Filarial / genetics
  • Elephantiasis, Filarial / immunology*
  • Elephantiasis, Filarial / parasitology
  • Female
  • Ghana
  • Humans
  • Interleukin-10 / genetics
  • Interleukin-10 / immunology*
  • Ivermectin / administration & dosage
  • Male
  • Middle Aged
  • T-Lymphocytes, Regulatory / immunology*
  • Th2 Cells / immunology
  • Wuchereria bancrofti / physiology*
  • Young Adult

Substances

  • Anthelmintics
  • Interleukin-10
  • Ivermectin
  • Albendazole

Grants and funding

This work was supported by German Research Foundation (DFG) [PF673/6-1 to KP and HO2009/11-1 to AH] and the BONFOR intramural funding program of the Medical Faculty of Bonn University. Furthermore, AH is financially supported by the German Ministry for Education and Research (BMBF initiative Research Networks for Health Innovations in Sub-Sahara Africa: TAKeOFF). In addition, AH and LEL are members of the Excellence Cluster Immunosensation (DFG, EXC 1023) and of the German Centre of Infectious Disease (DZIF). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.