Biology subjects

Roychoudhuri, R.

Publications and source records attributed to Roychoudhuri, R..

4 recordsLinked to original sources

bioRxiv2024

Lack of phosphatidylinositol 3-kinase VPS34 in regulatory T cells leads to a fatal lymphoproliferative disorder without affecting their development

Regulatory T (Treg) cells are essential for the maintenance of immunological tolerance, yet the molecular components required for their maintenance and effector functions remain incompletely defined. Inactivation of VPS34 in Treg cells led to an early, lethal phenotype, with massive effector T cell activation and inflammation, like mice lacking Treg cells completely. However, VPS34-deficient Treg cells developed normally, populated the peripheral lymphoid organs and effectively supressed conventional T cells in vitro. Our data suggest that VPS34 is required for the maturation of Treg cells or that mature Treg cells depend on VPS34 for survival. Functionally, we observed that lack of VPS34 activity impairs cargo processing upon transendocytosis, that defective autophagy contributes to, but is not sufficient to explain this lethal phenotype, and that loss of VPS34 activity induces a state of heightened metabolic activity that may interfere with metabolic networks required for maintenance or suppressive functions of Treg cells.

immunology↗

bioRxiv2023

Intracellular K+ limits T cell exhaustion and preserves antitumor function

The cancer-killing activity of T cells is often compromised within tumors, allowing disease progression. We previously found that intratumoral elevations in extracellular K+ related to ongoing cell death constrained CD8+ T cell Akt-mTOR signaling and effector function (1,2). To alleviate K+ mediated T cell suppression, we pursued genetic means to lower intracellular K+. Transcriptomic analysis of CD8+ T cells demonstrated the Na+/K+ ATPase to be robustly and dynamically expressed. CRISPR-Cas9 mediated deletion of the catalytic alpha subunit of the Na+/K+ ATPase lowered intracellular K+ but produced tonic hyperactivity in multiple signal transduction cascades along with the acquisition of co-inhibitory receptors and terminal differentiation in mouse and human CD8+ T cells. Mechanistically, Na+/K+ ATPase disruption led to ROS accumulation due to depletion of intracellular K+ in T cells. Antioxidant treatment or high K+ media prevented Atp1a1 deficient T cells from exhausted T (TEx) cell formation. Consistent with transcriptional and proteomic data suggesting a TEx cell phenotype, T cells lacking Atp1a1 had compromised persistence and antitumor activity in a syngeneic model of orthotopic murine melanoma. Translational application of these findings will include efforts to lower intracellular K+ while limiting ROS accumulation within tumor specific T cells. SynopsisHigh extracellular K+ ({uparrow}[K+]e) is found within tumors and suppresses T cell effector function. Collier et al. find that deletion of the Na+/K+ ATPase in T cells lowers intracellular K+ and promotes ROS accumulation, tonic signal transduction and T cell exhaustion owing to ROS accumulation. Engineering T cell ion transport is an important consideration for cancer immunotherapy.

immunology↗

bioRxiv2023

Time-, tissue- and treatment-associated heterogeneity in tumour-residing migratory DCs

Tumour dendritic cells (DCs) internalise antigen and upregulate CCR7, which directs their migration to tumour-draining lymph nodes (dLN). CCR7 expression is coupled to a maturation programme enriched in regulatory molecule expression, including PD-L1, termed mRegDC. However, the spatio- temporal dynamics and role of mRegDCs in anti-tumour immune responses remain unclear. Using photoconvertible mice to precisely track DC migration, we found that mRegDCs were the dominant DC population arriving in the dLN, but a subset remained tumour-resident despite CCR7 expression. These tumour-retained mRegDCs were phenotypically and transcriptionally distinct from their dLN counterparts and were heterogeneous. Specifically, they demonstrated a progressive reduction in the expression of antigen presentation and pro-inflammatory transcripts with more prolonged tumour dwell-time. Tumour mRegDCs spatially co-localised with PD-1+CD8+ T cells in human and murine solid tumours. Following anti-PD-L1 treatment, tumour-residing mRegDCs adopted a state enriched in lymphocyte stimulatory molecules, including OX40L, which was capable of augmenting anti- tumour cytolytic activity. Altogether, these data uncover previously unappreciated heterogeneity in mRegDCs that may underpin a variable capacity to support intratumoural cytotoxic T cells, and provide insights into their role in cancer immunotherapy.

immunology↗

bioRxiv2022

Multimodal single-cell profiling of intrahepatic cholangiocarcinoma defineshyperactivated Tregs as a potential therapeutic target

The quality of the immune infiltrate of intrahepatic cholangiocarcinoma (iCCA), a rare, yet aggressive tumor of the biliary tract, remains poorly characterized, limiting development of successful immunotherapies. We used high-dimensional flow cytometry to characterise the T cell and myeloid compartments of iCCA comparing these with their tumor-free peritumoral and circulating counterparts. We found poor infiltration of putative tumor-specific CD39+ CD8+ T cells accompanied by abundant infiltration of hyperactivated CD4+ regulatory T cells (Tregs), whose frequency in relation to that of CD4+ CD69+ T cells and conventional type 2 dendritic cells was associated with poor prognosis. Single-cell RNA-sequencing identified an altered network of transcription factors in iCCA-infiltrating compared to peritumoral T cells, suggesting reduced effector functions by tumor-infiltrating CD8+ T cells and enhanced immunosuppression by CD4+ Tregs. Specifically, we found that expression of mesenchyme homeobox 1 (MEOX1) was highly enriched in tumor-infiltrating Tregs, and demonstrated that MEOX1 overexpression is sufficient to reprogram circulating precursors to acquire the transcriptional and epigenetic landscape of tumorinfiltrating Tregs. Interfering with hyperactivated Tregs should be thus explored to enhance antitumor immunity in iCCA.

immunology↗