Product Citations: 12

RHOA Loss of Function Impairs the IFNγ Response and Promotes CD19 Antigen Escape to Drive CAR-T Resistance in Diffuse Large B-cell Lymphoma

Preprint on BioRxiv : the Preprint Server for Biology on 4 March 2025 by Newsam, A. D., Ziccheddu, B., et al.

ABSTRACT CD19-directed chimeric antigen receptor (CAR)-T cells are breakthrough therapies for aggressive B-cell lymphomas, but less than half of patients achieve durable responses. We previously showed through whole-genome sequencing of tumors from CAR-T-treated patients that deletions of RHOA (3p21.31) are enriched in cases progressing after treatment. RHOA ’s roles in resistance and pathogenesis are poorly defined, despite loss-of-function alterations that occur in ~20% of newly diagnosed diffuse large B-cell lymphoma (DLBCL) cases. To evaluate mechanisms of CAR-T resistance, we created RHOA-deficient DLBCL systems and confirmed cell-intrinsic loss of response to CAR-19 in vitro and in vivo. RHOA loss promotes AKT activation that impairs cell-intrinsic responses to interferon gamma (IFNγ). Moreover, expression of the CAR target CD19 is consistently down-regulated accompanied by a drive toward plasmablast differentiation. RHOA deficient tumors demonstrate greatly increased sensitivity to AKT-pathway inhibitors, which reverse impaired IFNγ responses. Lymphoma microenvironments in vivo in immunocompetent mice reveal that RHOA loss promotes decreased infiltration by cytotoxic T cells and enrichment of M2-polarized macrophages, known markers of CAR-T resistance in lymphoma clinical cases. Overall, we characterize RHOA deficiency as an AKT-mediated CAR-T resistance driver and implicate avoidance of T-cell mediated killing as a likely reason for RHOA’s frequent loss in DLBCL pathogenesis.

  • Cancer Research
  • Immunology and Microbiology

Moderate Aerobic Exercise Induces Homeostatic IgA Generation in Senile Mice.

In International Journal of Molecular Sciences on 27 July 2024 by Hernández-Urbán, A. J., Drago-Serrano, M. E., et al.

A T-cell-independent (TI) pathway activated by microbiota results in the generation of low-affinity homeostatic IgA with a critical role in intestinal homeostasis. Moderate aerobic exercise (MAE) provides a beneficial impact on intestinal immunity, but the action of MAE on TI-IgA generation under senescence conditions is unknown. This study aimed to determine the effects of long-term MAE on TI-IgA production in young (3 month old) BALB/c mice exercised until adulthood (6 months) or aging (24 months). Lamina propria (LP) from the small intestine was obtained to determine B cell and plasma cell sub-populations by flow cytometry and molecular factors related to class switch recombination [Thymic Stromal Lymphopoietin (TSLP), A Proliferation-Inducing Ligand (APRIL), B Cell Activating Factor (BAFF), inducible nitric oxide synthase (iNOS), and retinal dehydrogenase (RDH)] and the synthesis of IgA [α-chain, interleukin (IL)-6, IL-21, and Growth Factor-β (TGF-β)]; and epithelial cells evaluated IgA transitosis [polymeric immunoglobulin receptor (pIgR), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), IL-4] by the RT-qPCR technique. The results were compared with data obtained from sedentary age-matched mice. Statistical analysis was computed with ANOVA, and p < 0.05 was considered to be a statistically significant difference. Under senescence conditions, MAE promoted the B cell and IgA+ B cells and APRIL, which may improve the intestinal response and ameliorate the inflammatory environment associated presumably with the downmodulation of pro-inflammatory mediators involved in the upmodulation of pIgR expression. Data suggested that MAE improved IgA and downmodulate the cytokine pro-inflammatory expression favoring homeostatic conditions in aging.

  • Mus musculus (House mouse)

Moderate Aerobic Exercise Induces the Homeostatic IgA Generation in Senile Mice

Preprint on Preprints.org on 17 June 2024 by Hernández-Urbán, A. J., Drago-Serrano, M., et al.

T-cell independent (TI) pathway activated by microbiota results in the generation of low-affinity homeostatic IgA with a critical role in intestinal homeostasis. Moderate aerobic exercise (MAE) provides a beneficial impact on intestinal immunity but the action of MAE on TI-IgA generation under senescence conditions is unknown. This study aimed to determine the effects of long-term MAE on TI-IgA production in young (3 months old) BALB/c mice exercised until adulthood (6 months) or aging (24 months). Lamina propria (LP) from the small intestine was obtained to determine B cells and plasma cells sub-populations by flow cytometry and molecular factors related to class switch recombination (TSLP/APRIL/BAFF/iNOS/RDH) and synthesis of IgA (α-chain/IL-6/IL-21/TGF-β); and epithelial cells to evaluate IgA-transitosis (pIgR/TNFα/IFN-/IL-4), by RT-qPCR technique. Results were compared with data obtained from sedentary age-matched mice. Statistical analysis was computed with ANDOVA and P&lt;0.05 was considered as statistically significant difference. Under senescence conditions MAE promoted the B cell and IgA+B cells and APRIL that may im-prove the intestinal response and ameliorated the inflammatory environment associated pre-sumably with the downmodulation of pIgR. Data suggested that MAE improved the IgA and downmodulate the cytokine pro-inflammatory expression favoring homeostatic conditions in aging.

  • Mus musculus (House mouse)

DNA vaccines have been an attractive approach for treating cancer patients, however have demonstrated modest immunogenicity in human clinical trials. Dendritic cells (DCs) are known to cross-present DNA-encoded antigens expressed in bystander cells. However, we have previously reported that B cells, and not DCs, serve as primary antigen-presenting cells (APCs) following passive uptake of plasmid DNA. Here we sought to understand the requirements for B cells to present DNA-encoded antigens, to ultimately increase the immunogenicity of plasmid DNA vaccines. Using ovalbumin-specific OT-1 CD8+ T cells and isolated APC populations, we demonstrated that following passive uptake of plasmid DNA, B cells but not DC, can translate the encoded antigen. However, CD8 T cells were only activated by B cells when they were co-cultured with DCs. We found that a cell-cell contact is required between B cells and DCs. Using MHCI KO and re-purification studies, we demonstrated that B cells were the primary APCs and DCs serve to license this function. We further identified that the gene expression profiles of B cells that have been licensed by DCs, compared to the B cells that have not, are vastly different and have signatures similar to B cells activated with a TLR7/8 agonist. Our data demonstrate that B cells transcribe and translate antigens encoded by plasmid DNA following passive uptake, however require licensing by live DC to present antigen to CD8 T cells. Further study of the role of B cells as APCs will be important to improve the immunological efficacy of DNA vaccines.
© 2023 The Author(s). Published with license by Taylor & Francis Group, LLC.

  • FC/FACS
  • Mus musculus (House mouse)
  • Genetics
  • Immunology and Microbiology

Differential H4K16ac levels ensure a balance between quiescence and activation in hematopoietic stem cells.

In Science Advances on 1 August 2021 by Pessoa Rodrigues, C. & Akhtar, A.

Hematopoietic stem cells (HSCs) are able to reconstitute the bone marrow while retaining their self-renewal property. Individual HSCs demonstrate heterogeneity in their repopulating capacities. Here, we found that the levels of the histone acetyltransferase MOF (males absent on the first) and its target modification histone H4 lysine 16 acetylation are heterogeneous among HSCs and influence their proliferation capacities. The increased proliferative capacities of MOF-depleted cells are linked to their expression of CD93. The CD93+ HSC subpopulation simultaneously shows transcriptional features of quiescent HSCs and functional features of active HSCs. CD93+ HSCs were expanded and exhibited an enhanced proliferative advantage in Mof +/- animals reminiscent of a premalignant state. Accordingly, low MOF and high CD93 levels correlate with poor survival and increased proliferation capacity in leukemia. Collectively, our study indicates H4K16ac as an important determinant for HSC heterogeneity, which is linked to the onset of monocytic disorders.
Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).

  • FC/FACS
  • Mus musculus (House mouse)
  • Stem Cells and Developmental Biology
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