Adrian Liston

MicroRNA miR-29c regulates RAG1 expression and modulates V(D)J recombination during B cell development.
Kumari R, Roy U, Desai S, Nilavar NM, Van Nieuwenhuijze A, Paranjape A, Radha G, Bawa P, Srivastava M, Nambiar M, Balaji KN, Liston A, Choudhary B, Raghavan SC

Recombination activating genes (RAGs), consisting of RAG1 and RAG2, are stringently regulated lymphoid-specific genes, which initiate V(D)J recombination in developing lymphocytes. We report the regulation of RAG1 through a microRNA (miRNA), miR-29c, in a B cell stage-specific manner in mice and humans. Various lines of experimentation, including CRISPR-Cas9 genome editing, demonstrate the target specificity and direct interaction of miR-29c to RAG1. Modulation of miR-29c levels leads to change in V(D)J recombination efficiency in pre-B cells. The miR-29c expression is inversely proportional to RAG1 in a B cell developmental stage-specific manner, and miR-29c null mice exhibit a reduction in mature B cells. A negative correlation of miR-29c and RAG1 levels is also observed in leukemia patients, suggesting the potential use of miR-29c as a biomarker and a therapeutic target. Thus, our results reveal the role of miRNA in the regulation of RAG1 and its relevance in cancer.

Cell reports, 36, 2, 13 Jul 2021

Monocyte-driven atypical cytokine storm and aberrant neutrophil activation as key mediators of COVID-19 disease severity.
Vanderbeke L, Van Mol P, Van Herck Y, De Smet F, Humblet-Baron S, Martinod K, Antoranz A, Arijs I, Boeckx B, Bosisio FM, Casaer M, Dauwe D, De Wever W, Dooms C, Dreesen E, Emmaneel A, Filtjens J, Gouwy M, Gunst J, Hermans G, Jansen S, Lagrou K, Liston A, Lorent N, Meersseman P, Mercier T, Neyts J, Odent J, Panovska D, Penttila PA, Pollet E, Proost P, Qian J, Quintelier K, Raes J, Rex S, Saeys Y, Sprooten J, Tejpar S, Testelmans D, Thevissen K, Van Buyten T, Vandenhaute J, Van Gassen S, Velásquez Pereira LC, Vos R, Weynand B, Wilmer A, Yserbyt J, Garg AD, Matthys P, Wouters C, Lambrechts D, Wauters E, Wauters J

Epidemiological and clinical reports indicate that SARS-CoV-2 virulence hinges upon the triggering of an aberrant host immune response, more so than on direct virus-induced cellular damage. To elucidate the immunopathology underlying COVID-19 severity, we perform cytokine and multiplex immune profiling in COVID-19 patients. We show that hypercytokinemia in COVID-19 differs from the interferon-gamma-driven cytokine storm in macrophage activation syndrome, and is more pronounced in critical versus mild-moderate COVID-19. Systems modelling of cytokine levels paired with deep-immune profiling shows that classical monocytes drive this hyper-inflammatory phenotype and that a reduction in T-lymphocytes correlates with disease severity, with CD8+ cells being disproportionately affected. Antigen presenting machinery expression is also reduced in critical disease. Furthermore, we report that neutrophils contribute to disease severity and local tissue damage by amplification of hypercytokinemia and the formation of neutrophil extracellular traps. Together our findings suggest a myeloid-driven immunopathology, in which hyperactivated neutrophils and an ineffective adaptive immune system act as mediators of COVID-19 disease severity.

Nature communications, 12, 1, 05 07 2021

Treatment-Induced BAFF Expression and B Cell Biology in Multiple Sclerosis.
Smets I, Prezzemolo T, Imbrechts M, Mallants K, Mitera T, Humblet-Baron S, Dubois B, Matthys P, Liston A, Goris A

Although fingolimod and interferon-β are two mechanistically different multiple sclerosis (MS) treatments, they both induce B cell activating factor (BAFF) and shift the B cell pool towards a regulatory phenotype. However, whether there is a shared mechanism between both treatments in how they influence the B cell compartment remains elusive. In this study, we collected a cross-sectional study population of 112 MS patients (41 untreated, 42 interferon-β, 29 fingolimod) and determined B cell subsets, cell-surface and RNA expression of BAFF-receptor (BAFF-R) and transmembrane activator and cyclophilin ligand interactor (TACI) as well as plasma and/or RNA levels of BAFF, BAFF splice forms and interleukin-10 (IL-10) and -35 (IL-35). We added an B cell culture with four stimulus conditions (Medium, CpG, BAFF and CpG+BAFF) for untreated and interferon-β treated patients including measurement of intracellular IL-10 levels. Our flow experiments showed that interferon-β and fingolimod induced BAFF protein and mRNA expression (P ≤ 3.15 x 10) without disproportional change in the antagonizing splice form. Protein BAFF correlated with an increase in transitional B cells (P = 5.70 x 10), decrease in switched B cells (P = 3.29 x 10), and reduction in B cell-surface BAFF-R expression (P = 2.70 x 10), both on TACI-positive and -negative cells. TACI and BAFF-R RNA levels remained unaltered. RNA, plasma and experiments demonstrated that BAFF was not associated with increased IL-10 and IL-35 levels. In conclusion, treatment-induced BAFF correlates with a shift towards transitional B cells which are enriched for cells with an immunoregulatory function. However, BAFF does not directly influence the expression of the immunoregulatory cytokines IL-10 and IL-35. Furthermore, the post-translational mechanism of BAFF-induced BAFF-R cell surface loss was TACI-independent. These observations put the failure of pharmaceutical anti-BAFF strategies in perspective and provide insights for targeted B cell therapies.

Frontiers in immunology, 12, 1, 2021