Biology subjects

Leite, J. A.

Publications and source records attributed to Leite, J. A..

3 recordsLinked to original sources

bioRxiv2026

HIF-1α integrates metabolic and immunoregulatory programs in RORγt⁺ regulatory T cells during intestinal inflammation

Regulatory T (Treg) cells expressing ROR{gamma}t accumulate in the intestinal mucosa, yet the signals that determine whether they remain suppressive or acquire inflammatory features are incompletely defined. We first reanalyzed human ileal single-cell data and identified Crohns disease-enriched FOXP3 states in which RORC, HIF1A, hypoxia-responsive, inflammatory, and metabolic programs converged. We then deleted Hif1a in ROR{gamma}t-expressing cells and tested acute DSS colitis, T cell transfer colitis, and azoxymethane/DSS-induced colitis-associated colorectal cancer (CAC). {Delta}Hif1a mice were protected in all three settings. In lymphopenic recipients given the same pathogenic naive T cells, changing only the genotype of the cotransferred Treg population enhanced protection, linking the phenotype to regulatory-cell function in vivo. Reanalysis of mouse colonic Treg single-cell ATAC-seq nominated suppressive and mitochondrial programs for cell-intrinsic testing during low HIF1- expression. {Delta}Hif1a ROR{gamma}t Treg produced more IL-10 and less IL-17A and IFN-{gamma}, limited responder-cell proliferation, contained fewer dysfunctional and mitochondrial-reactive-oxygen-species-high mitochondria, favored fusion-associated transcription, and displayed greater basal and maximal oxygen consumption and reserve capacity. During CAC, HIF-1 loss blunted inflammatory ROR{gamma}t Treg accumulation and reduced tumor burden. Human trajectory and gene-regulatory-network analyses further predicted that HIF1A perturbation would oppose selected disease-associated branches. Together, these findings identify HIF-1 as a context-dependent checkpoint that connects hypoxia-responsive transcription to mitochondrial fitness and inflammatory plasticity in intestinal ROR{gamma}t Treg.

immunology↗

bioRxiv2025

Aging-Associated Microbiota Drives Treg Dysfunction via TNF Signaling

Aging is associated with a chronic, low-grade inflammatory state referred to as inflammaging, which contributes to impaired immune regulation and increased susceptibility to disease. While regulatory T (Treg) cells are key mediators of immune homeostasis, their role in the context of age-related inflammation remains poorly understood. Here we demonstrate that age-related changes in the microbiota promote impaired Treg cell function, resulting in the differentiation of inflammatory T cells. In agreement, we find that aged germ-free (GF) mice exhibited a more balanced immune profile, where the Treg cells are functional and pro-inflammatory mediators are reduced, suggesting that microbial exposure is essential for the establishment of inflammaging. Furthermore, we show that the use of old microbiota in young animals was sufficient to induce pro-inflammatory T cell responses and impaired mucosal Treg cell proliferation, while young microbiota restored Treg cell function in old animals. Mechanistically, we show that exposure to aged microbiota was associated with sustained TNF signaling, elevated oxidative stress, DNA damage, and increased expression of senescence markers such as {gamma}H2AX and p16 in Treg cells. These findings uncover a microbiota-TNF-dependent mechanism by which age-associated microbial dysbiosis drives Treg cell dysfunction and promotes immune aging, highlighting the therapeutic potential of microbiota-targeted strategies to restore immune homeostasis in the elderly.

immunology↗

bioRxiv2024

Th17 cells require the DNA repair sensor XPC to control oxidative DNA damage

Th17 cells are critical for mucosal immunity, producing IL-17A, IL-17F, and IL-22, but dysregulated Th17 responses are implicated in autoimmune diseases. Despite their susceptibility to oxidative stress in certain conditions, Th17 cells exhibit reduced oxidative DNA damage and cell death compared to other T helper subsets. However, the mechanisms that protect Th17 cells from oxidative stress are poorly understood. Here, we identify Xeroderma Pigmentosum Complementation Group C (XPC) as a key regulator of DNA repair and genomic stability in Th17 cells. In XPC-deficient mice, we demonstrate that the absence of XPC impairs Th17 differentiation, as evidenced by reduced expression of key differentiation markers, including Rorc and Il17a, along with decreased IL-17A production. This deficiency leads to increased oxidative stress, DNA damage, and a metabolic shift from glycolysis to oxidative phosphorylation. Moreover, the transcription factor BATF directly regulates XPC expression, linking the BATF-XPC axis to the maintenance of Th17 cell function. Importantly, we find that restoring antioxidant capacity with N-Acetylcysteine (NAC) rescues IL-17A production and reduces DNA damage in XPC-deficient Th17 cells. Mechanistically, we find that XPC interacts with OGG1, a DNA glycosylase involved in the repair of oxidative DNA damage, highlighting XPCs role in maintaining genomic integrity during Th17 cell differentiation. Our findings reveal a previously unrecognized role for XPC in protecting Th17 cells from oxidative stress, ensuring their proper differentiation and function, with potential implications for targeting DNA repair pathways in autoimmune and inflammatory diseases.

immunology↗