Biology subjects

Villarino, A. V.

Publications and source records attributed to Villarino, A. V..

8 recordsLinked to original sources

bioRxiv2026

MicroRNA-29a enhances and preserves stem-like CD8 T cell differentiation by regulating master epigenetic circuits of exhaustion.

CD8 T cells mediate protective immune responses. However, persisting antigens such as chronic viruses or tumors redirect CD8 T cell differentiation to a sub-optimal, epigenetically defined state called exhaustion. Exhausted T cells (TEX) lose their ability to persist long-term and to initiate functional memory responses. Checkpoint inhibitor blockade temporarily restores effector functions, but immune reinvigoration is not long-lasting, due to the epigenetic stability of TEX. Therefore, epigenetic reprogramming of TEX leading to durable T cell responses is essential to improve disease control. Here, we demonstrate that a single microRNA (miR), miR-29a, epigenetically re-directs TEX differentiation and preserves TEX into a stem-like state, leading to long-term persisting progenitor TEX. MiR-29a rewires epigenetic maintenance programs, including downregulation of key exhaustion-associated regulators (Dnmt1, Dnmt3a, and Dnmt3b), alongside increased expression of progenitor- and stemness-associated genes such as Tcf7 and Il7r. These reprogrammed CD8 T cells are more sensitive to PD-L1 checkpoint blockade. Ectopic expression of miR-29a combined with aPD-L1 treatments enhances effector responses, while preserving T cell stemness. Together, our findings suggest that miR-29a can be leveraged to overcome current barriers to immune checkpoint blockade. HighlightsO_LIMiR-29a rewires key exhaustion-associated epigenetic maintenance programs, while enhancing stemness-associated transcriptional circuits. C_LIO_LIMiR-29a drives extensive remodeling of accessible chromatin in TEX. C_LIO_LIMiR-29a preserves newly generated progenitor TEX in a durable, epigenetically defined stem-like state with increased effector function. C_LIO_LIMiR-29a synergizes with aPD-L1; while miR-29a preserves progenitor TEX state, addition of aPD-L1 enhances the cytotoxic potential of these progenitor TEX cells. C_LI

immunology↗

bioRxiv2025

B12 promotes gut dysbiosis and an inflammatory microenvironment that potentiates Tet2-deficient hematopoiesis.

Recent studies have linked elevated vitamin B12 serum levels with the presence of clonal hematopoiesis (CH) and an increased risk of developing myeloid malignancy. High B12 supplementation increases serum levels, alters gut microbial composition, and reduces the production of short-chain fatty acids (SCFAs), which help maintain gut barrier function and mucosal integrity. TET2 mutation is a frequent driver of CH that progresses in a positive feedback loop in response to microbial signals suggesting that B12 may influence CH via the gut microbiome. We evaluated the microenvironmental effects of B12 supplementation in a Tet2-deficient model of CH and found that B12 enhances myelopoiesis, heightens the responses of myeloid cells to bacterial stimuli, and increases the levels of circulating inflammatory cytokines. B12 supplementation also induced gut dysbiosis and reduced the levels of SCFA-producing bacteria in both wild-type and Tet2-deficient mice. Importantly, the effects of excess B12 were reversible upon oral supplementation with the SCFA butyrate. These findings suggest that B12 may promote CH progression by disrupting microbiome-derived SCFA metabolism, highlighting a potential therapeutic role for SCFA supplementation in mitigating CH.

cancer biology↗

bioRxiv2025

Asymmetry and redundancy of STAT5 paralogs across CD8+ T cell differentiation states

Fostering STAT5 signaling is key to immunotherapies that leverage CD8+ T cell biology. Using mouse models, we demonstrate that the two mammalian STAT5 paralogs, STAT5A and STAT5B, are at once redundant and functionally distinct in CD8+ T cells. Specifically, we establish that they are asymmetric paralogs, exhibiting both widespread homology at molecular level and functional asymmetry at cellular level, with STAT5B emerging as dominant. In fact, compared to STAT5A, STAT5B deficiency had greater impact on nearly all parameters tested. As a mechanism, we determined STAT5B is twice as abundant, accounting for two-thirds of the total STAT5 pool. We also defined both cytokine- and cell state-restricted STAT5B functions, and a core gene signature that highlights universal effects. Together, these studies affirm the centrality of STAT5 in CD8+ T cells, reveal common and circumscribed activities, and present a unifying model for paralog redundancy that foregrounds and explains the dominance of STAT5B. Summary: STAT5 paralog dominance and redundancy in CD8+ T cells

immunology↗

bioRxiv2025

Preserved suppressive function despite loss of Foxp3: insights into the identity of regulatory T cells

Regulatory T (Treg) cells are essential for maintaining immune homeostasis, with Foxp3 acting as the master transcription factor governing their differentiation and function. The acquisition of effector signatures in Treg cells is closely tied to the surrounding tissue-specific immune environment and typically occurs alongside Foxp3 expression. In this study, we investigated the transcriptomic and functional consequences of Treg-mediated regulation in a Th2-driven disease setting. The application of both in vitro systems and in vivo disease models allowed us to mimic Th2-mediated environments. We could demonstrate Th2-driven loss of Foxp3 expression in Treg cells in vitro and in vivo. Transcriptomic analysis revealed a maintained Treg signature despite the loss of active Foxp3 expression. Functional characterization of Tregs both in vitro and in vivo uncovered a preserved suppressive capacity even in the absence of Foxp3. Our findings unveil that, despite loss of Foxp3, a preserved Treg signature remains intact enabling the regulation of Th2-mediated diseases. The persistence of this regulatory transcriptome highlights the importance for developing Treg-cell therapy strategies in cancer and autoimmune diseases independent of Foxp3 expression.

immunology↗

bioRxiv2024

STAT5B leukemic mutations, altering SH2 tyrosine 665, have opposing impacts on immune gene programs

STAT5B is a vital transcription factor for lymphocytes. Here, function of two STAT5B mutations from human T cell leukemias: one substituting tyrosine 665 with phenylalanine (STAT5BY665F), the other with histidine (STAT5BY665H) was interrogated. In silico modeling predicted divergent energetic effects on homodimerization with a range of pathogenicity. In primary T cells in vitro STAT5BY665F showed gain-of-function while STAT5BY665H demonstrated loss-of-function. Introducing the mutation into the mouse genome illustrated that the gain-of-function Stat5bY665F mutation resulted in accumulation of CD8+ effector and memory and CD4+ regulatory T-cells, altering CD8+/CD4+ ratios. In contrast, STAT5BY665H knock-in mice showed diminished CD8+ effector and memory and CD4+ regulatory T cells. In contrast to wild-type STAT5, the STAT5BY665F variant displayed greater STAT5 phosphorylation, DNA binding and transcriptional activity following cytokine activation while the STAT5BY665H variant resembled a null. The work exemplifies how joining in silico and in vivo studies of single nucleotides deepens our understanding of disease-associated variants, revealing structural determinants of altered function, defining mechanistic roles, and, specifically here, identifying a gain-of function variant that does not directly induce hematopoietic malignancy.

genetics↗

bioRxiv2024

Altered Purinergic Signaling and CD8+ T Cell Dysregulation in STAT3 GOF Syndrome

Signal transduction downstream of activating stimuli controls CD8+ T cell biology, however these external inputs can become uncoupled from transcriptional regulation in Primary Immune Regulatory Disorders (PIRD). Gain-of-function (GOF) variants in STAT3 amplify cytokine signaling and cause a severe PIRD characterized by early onset autoimmunity, lymphoproliferation, recurrent infections, and immune dysregulation. In both primary human and mouse models of STAT3 GOF, CD8+ T cells have been implicated as pathogenic drivers of autoimmunity. The molecular mechanisms by which STAT3 GOF variants drive this pathology remain unclear. We found that naive CD8+ T cells have an increased capacity for IFN-{gamma} and TNF- secretion. Given this dysregulation of CD8+ T cell function, we evaluated changes in immunoregulatory pathways and found evidence of dysregulated purinergic signaling via high dimensional immune profiling, single-cell RNA sequencing, and functional assessment. Specifically, while expression of CD39, which transforms ATP to AMP, was increased on CD8+ T cells from patients with STAT3 GOF, downstream purinergic family members, CD73 and the adenosine receptor, A2AR, were downregulated, impairing the potential to produce or sense inhibitory adenosine. Patients with STAT3 GOF can be clinically treated with JAK inhibitors and this partially normalized naive CD8+ T cell dysregulation, including aberrant cytokine production. The extent of normalization of cytokine secretion scaled with normalization of CD73 and A2AR. This suggests that a dysregulated purinergic signaling axis plays an important role in CD8+ T cell dysregulation in STAT3 GOF, which may have implications for other inflammatory disorders with amplified STAT signaling. One Sentence SummaryAmplified STAT3 signaling in CD8+ T cells from STAT3 GOF patients alters purinergic signaling and dysregulates CD8+ T cell function.

immunology↗

bioRxiv2024

A PI3Kδ-Foxo1-FasL signaling amplification loop rewires CD4+ T helper cell signaling, differentiation and epigenetic remodeling

While inputs regulating CD4+ T helper cell (Th) differentiation are well-defined, the integration of downstream signaling with transcriptional and epigenetic programs that define Th-lineage identity remain unresolved. PI3K signaling is a critical regulator of T cell function; activating mutations affecting PI3K{delta} result in an immunodeficiency with multiple T cell defects. Using mice expressing activated-PI3K{delta}, we found aberrant expression of proinflammatory Th1-signature genes under Th2-inducing conditions, both in vivo and in vitro. This dysregulation was driven by a robust PI3K{delta}-IL-2-Foxo1 signaling loop, fueling Foxo1-inactivation, loss of Th2-lineage restriction, altered chromatin accessibility and global impairment of CTCF-DNA interactions. Surprisingly, ablation of Fasl, a Foxo1-repressed gene, restored normal Th2 differentiation, TCR signaling and CTCF expression. BioID revealed Fas interactions with TCR- signaling components, which were supported by Fas-mediated potentiation of TCR signaling. Our results highlight Fas-FasL signaling as a critical intermediate in phenotypes driven by activated-PI3K{delta}, thereby linking two key pathways of immune dysregulation.

immunology↗

bioRxiv2019

Increased Th1 bias in memory T cells corresponds with protection from reinfection in Plasmodium infection, and is regulated by T cell-intrinsic STAT3

Hybrid Th1/Tfh cells (IFN-{gamma}+IL-21+CXCR5+) predominate in response to persistent infections; however, molecular regulation of their function is poorly defined. In infection with Plasmodium spp, an IFN-{gamma}+ T helper-1 (Th1) response controls initial parasitemia, while antibody and IL-21+CXCR5+ T follicular helper (Tfh) function effect final clearance. Here, we found that CD4-intrinsic Bcl6, Blimp-1 and STAT3 all regulate T-bet expression, which controls IFN-{gamma} expression. While Bcl6 and Blimp-1 regulate the level of CXCR5, only T-bet and STAT3 affected the functional bias of the Th1/Tfh phenotype. Infected mice with STAT3-deficient T cells produced less antibody, and more IFN-{gamma}+IL-21-CXCR5lo T cells, significantly increasing protection from re-infection. Conversely, reduced Th1 bias in re-infected T-bet KO was reflected in prolonged secondary parasitemia. In summary, each feature of hybrid Th1/Tfh population in Plasmodium infection is uniquely regulated and the cytokine bias of memory T cells can be modified to enhance the effectiveness of the response.

immunology↗