bims-maitce 2023-11-05 papers

Issue of 2023–11–05
two papers selected by
Andy E. Hogan, Maynooth University

PLoS One. 2023 ;18(11): e0285918

Colonic mucosal associated invariant T cells in Crohn's disease have a diverse and non-public T cell receptor beta chain repertoire.

Andrew J Konecny, Donna M Shows, James D Lord.

OBJECTIVES: Mucosal-Associated Invariant T (MAIT) cells are T cells with a semi-invariant T cell receptor (TCR), recognizing riboflavin precursors presented by a non-polymorphic MR1 molecule. As these precursors are produced by the gut microbiome, we characterized the frequency, phenotype and clonality of MAIT cells in human colons with and without Crohn's disease (CD).
METHODS: The transcriptome of MAIT cells sorted from blood and intestinal lamina propria cells from colectomy recipients were compared with other CD8+ T cells. Colon biopsies from an additional ten CD patients and ten healthy controls (HC) were analyzed by flow cytometry. TCR genes were sequenced from individual MAIT cells from these biopsies and compared with those of MAIT cells from autologous blood.
RESULTS: MAIT cells in the blood and colon showed a transcriptome distinct from other CD8 T cells, with more expression of the IL-23 receptor. MAIT cells were enriched in the colons of CD patients, with less NKG2D in inflamed versus uninflamed segments. Regardless of disease, most MAIT cells expressed integrin α4β7 in the colon but not in the blood, where they were enriched for α4β7 expression. TCR sequencing revealed heterogeneity in the colon and blood, with few public sequences associated with cohorts.
CONCLUSION: MAIT cells are enriched in the colons of CD patients and disproportionately express molecules (IL-23R, integrin α4β7) targeted by CD therapeutics, to suggest a pathogenic role for them in CD. Public TCR sequences were neither common nor sufficiently restricted to a cohort to suggest protective or pathogenic antigen-specificities.

DOI: https://doi.org/10.1371/journal.pone.0285918

Biomed Rep. 2023 Dec;19(6): 95

IgG from patients with mild or severe COVID‑19 reduces the frequency and modulates the function of peripheral mucosal-associated invariant T cells in PBMCs from healthy individuals.

Nicolle Rakanidis Machado, Beatriz Oliveira Fagundes, Iara Grigoletto Fernandes, Daniela Terra De Apoena Reche, Maria Notomi Sato, Jefferson Russo Victor.

Lower levels of peripheral mucosal-associated invariant T (MAIT) cells have been observed in the peripheral blood of patients with severe coronavirus disease 2019 (COVID-19). Following on from previous research into the effect of the IgG repertoire on human lymphocytes, the present study aimed to evaluate if immunoglobulin G (IgG) antibodies obtained from patients with mild or severe COVID-19 contribute to these effects on MAIT cells. Culture experiments were performed using healthy human peripheral blood mononuclear cells (PBMCs) and different repertoires of IgG obtained from patients with COVID-19 as a mild or severe disease and compared with mock, healthy control or therapeutic IgG conditions. The results indicate that the IgG repertoire induced during the development of mild and severe COVID-19 has, per se, the in vitro potential to reduce the frequency of MAIT cells and the production of IFN-γ by the MAIT cell population in PBMCs from healthy individuals. In conclusion, the results of the present study indicate that IgG in patients with severe COVID-19 may participate in the reduction of peripheral MAIT cell frequency and hinder the antiviral activity of these cells.

Keywords: COVID-19; IFN-γ; IL-17; IgG; mucosal-associated invariant T cells

DOI: https://doi.org/10.3892/br.2023.1677