BMC Med . Helminth antigens differentially modulate the activation of CD4 + and CD8 + T lymphocytes of convalescent COVID-19 patients in vitro

[tetano]

BMC Med


. 2022 Jun 28;20(1):241.
doi: 10.1186/s12916-022-02441-x.
Helminth antigens differentially modulate the activation of CD4 ⁺ and CD8 ⁺ T lymphocytes of convalescent COVID-19 patients in vitro


Tomabu Adjobimey ^{1 2} , Julia Meyer ³ , Vedrana Terkeš ⁴ , Marijo Parcina ³ , Achim Hoerauf ^{3 5}



Affiliations

• PMID: 35764965
• DOI: 10.1186/s12916-022-02441-x

Abstract

Background: The coronavirus disease 2019 (COVID-19) is a respiratory disease caused by SARS-CoV-2, a recently discovered strain of coronavirus. The virus has spread rapidly, causing millions of death worldwide. Contrary to the predictions, prevalence and mortality due to COVID-19 have remained moderate on the African continent. Several factors, including age, genetics, vaccines, and co-infections, might impact the course of the pandemic in Africa. Helminths are highly endemic in Sub-Saharan Africa and are renowned for their ability to evade, skew, and suppress human immune responses through various immune-modulatory mechanisms. Such effects will likely impact SARS-CoV-2 transmission and disease progression.
Methods: Here, we analyzed in vitro the impact of antigen extracts from three major helminth parasites, including Onchocerca volvulus, Brugia malayi, and Ascaris lumbricoides, on the immune reactivity to SARS-CoV-2 peptides in COVID-19 patients. Activation of CD4⁺ and CD8⁺ T cells was investigated using flow cytometry to monitor the expression of CD137 (4-1BB) and CD69. Cytokine expression, including IL-6, IL-10, IFN-γ, and TNFα, was measured by Luminex in cell culture supernatants.
Results: We observed that helminth antigens significantly reduced the frequency of SARS-CoV-2-reactive CD4⁺ T helper cells. In contrast, the expression of SARS-CoV-2-reactive CD8⁺ T cells was not affected and even significantly increased when PBMCs from COVID-19 patients living in Benin, an endemic helminth country, were used. In addition, stimulation with helminth antigens was associated with increased IL-10 and a reduction of IFNγ and TNFα.
Conclusions: Our data offer a plausible explanation for the moderate incidence of COVID-19 in Africa and support the hypothesis that helper T cell-mediated immune responses to SARS-CoV-2 are mitigated in the presence of helminth antigens, while virus-specific cytotoxic T cell responses are maintained.

Keywords: CD137 (4-1BB); CD4+ helper and CD8+ T cytotoxic T cells; CD69; COVID-19; Helminth antigens; SARS-CoV-2; activation markers.