Veltkamp, F. | bioRxiv Science

bioRxiv2025

Levamisole-Mediated Suppression of B-Cell Proliferation and Antibody Production Reveals Mechanistic Insights into Idiopathic Nephrotic Syndrome Therapy

Levamisole (LMS) is a small imidazole derivative with immunomodulatory properties. Despite its longstanding clinical use in Idiopathic Nephrotic Syndrome (INS), the mechanisms underlying its immune-regulating effects remain poorly defined. In this study, we investigated the in vitro effects of LMS treatment on human B-cells, and in patients included from the LEARNS (LEvamisole as Adjuvant therapy to Reduce relapses of Nephrotic Syndrome) clinical trial. In vitro experiments showed that LMS directly suppresses activation and proliferation in both T-cell dependent and T-cell independent stimulated B-cells, without inducing cytotoxicity. In agreement, transcriptomic profiling demonstrated downregulation of cell cycle-associated genes and genes involved in immunoglobulin synthesis, while genes involved in terminal B-cell differentiation were upregulated, including SLAMF7. Consistently, LMS treatment decreased immunoglobulin expression and secretion while simultaneously inducing the expression of factors associated with a more terminal B-cell phenotype (CD138/CD319). Flowcytometry analysis of blood samples from LMS-treated INS patients revealed reduced circulating B-cell counts. Collectively, these data suggest that LMS acts as a potent modulator of B-cell function that inhibits proliferation and immunoglobulin synthesis, providing mechanistic support for its therapeutic efficacy in INS management.

immunology↗

bioRxiv2023

Levamisole suppresses activation and proliferation of human T cells by the induction of a p53-dependent DNA damage response

Levamisole (LMS) is a small molecule used in the treatment of idiopathic nephrotic syndrome (INS). The pathogenesis of INS remains unknown, but most evidence points towards an immunological basis of the disease. Recently, LMS has been shown to increase the relapse-free survival in INS patients treated in combination with corticosteroids with relatively few side effects. While LMS has been hypothesized to exert an immunomodulatory effect, its mechanism of action remains unknown. To provide insight into the working mechanism of LMS, we studied its immunomodulatory activity on in vitro activated human T cells. We show here that treatment with LMS decreased activation and proliferation of human CD4+ and CD8+ T cells. In addition, production of T cell activation-associated cytokines such as IL-2, TNF- and IFN-{gamma} were reduced upon LMS treatment, whereas IL-4 and IL-13 production was increased. Gene expression profiling confirmed the suppressive effects of LMS on proliferation as numerous genes involved in cell cycle progression were downregulated. Furthermore, genes associated with p53 activation and cell cycle arrest were upregulated by LMS. In agreement, LMS treatment resulted in p53 phosphorylation and increased expression of the p53 target gene FAS. Accordingly, LMS sensitized activated T cells for Fas-mediated apoptosis. Cell cycle analysis showed that LMS induced a mid-S phase arrest indicating the activation of a replication stress-associated checkpoint. In support, LMS treatment resulted in {gamma}H2AX-foci formation and phosphorylation of CHK1. Our findings indicate that LMS acts as an immunosuppressive drug that directly affects the activation and proliferation of human T cells by induction of DNA damage and the activation of a p53-dependent DNA damage response.

immunology↗