Borges da Silva, Henrique

Abstract Lichen Planopilaris (LPP) is a lymphocyte-mediated scarring alopecia characterized by progressive follicular destruction and fibrosis. In this clinical trial, patients with biopsy proven LPP were treated with deucravacitinib (an oral inhibitor of tyrosine kinase 2 (TYK2)) 6 mg BID for 24 weeks (NCT-06091956). Bulk and single-cell RNA sequencing was performed on paired pre- and post-treatment scalp biopsies from baseline and week 4. Patients (N=10) demonstrated improvements in PGA (88.9%, p=0.008), LPPAI (−2.3 points, SD 1.1, p=0.002) and Skindex-16 (−21.0 points, SD 22.1, p=0.014) scores at week 24. Bulk transcriptomic analysis of untreated LPP revealed upregulation of type I Interferon (IFN)-stimulated genes and pathways related to inflammation, immune activation, keratinization, and extracellular matrix remodelling, with downregulation of immune and inflammatory pathways following treatment. Single-cell RNA-seq of LPP was characterized by enrichment of CD8+GZMK+ T cells which showed downregulation of T-cell receptor signaling as well as antiviral pathways with treatment. Basal keratinocytes exhibited reduced cytokine and interferon signaling and decreased communication with NK cells following treatment. CCL19+ fibroblasts were prominent in untreated disease was attenuated after treatment, with downregulation of type I IFN signaling. Selective TYK2 inhibition with deucravacitinib effectively suppresses these inflammatory circuits in LPP and represents a promising therapeutic strategy.

Abstract Lung cancer is the leading cause of cancer-related deaths worldwide, and despite advances in treatment, immune suppression remains an obstacle to effective therapy. Effector CD4+ T cells (CD4+ Teff) are critical for antitumor immunity, but their function is often inhibited by regulatory T cells (Treg), which accumulate in lung tumors and mediate suppressive functions through multiple mechanisms. This suppression leads to tumor progression and poor patient outcomes. However, the mechanisms underlying Treg-mediated suppression are not fully understood. Herein, we identify the extracellular adenosine 5-triphosphate receptor P2RX7 as a key regulator of Treg function in lung tumors. In a murine lung cancer model induced by Lewis lung carcinoma cells, we found that P2RX7 enhanced the suppressive capacity of tumor-infiltrating Tregs, promoting tumor growth. In T cell–specific P2RX7-knockout (P2RX7-KO) mice, reduced Treg infiltration was accompanied by increased CD4+ Teff accumulation and improved tumor control. Treg-specific P2RX7-KO mice exhibited reduced tumor growth, confirming a Treg-intrinsic role of P2RX7. Suppression assays revealed that tumor-infiltrating wild-type Tregs had greater suppressive activity compared with P2RX7-KO Tregs, which failed to inhibit type 1 and follicular helper T–like responses. This was associated with increased tumor-specific IgG production by lung B cells in P2RX7-KO mice. We also observed that wild-type Tregs expressed higher levels of the immunosuppressive molecule CTLA-4 when compared with P2RX7-KO Tregs. Thus, we conclude that P2RX7 expression on Tregs is essential for their suppressive function in lung cancer and targeting P2RX7 may constitute a strategy to improve lung cancer treatment by alleviating Treg-mediated immune suppression.

Abstract The effectiveness of T cell–based immunotherapy depends on durable T-cell responses that can efficiently eliminate tumor cells. NKG7 was discovered three decades ago as a protein associated with lytic granules. However, only studies published over the past 5 years have contributed substantially to our understanding of NKG7 in T-cell biology. NKG7 has been recognized as an important T-cell functional marker in responses to immune checkpoint inhibitor therapy and in the prognosis of certain cancers. Besides its role in the generation, trafficking, and release of lytic granules, which is critical for efficient T-cell cytotoxicity against tumor cells, NKG7 has been identified as a key negative regulator of mTORC1 activity. By restraining mTORC1 activity, NKG7 promotes T-cell longevity and memory generation after infection. Importantly, NKG7 upregulation has demonstrated therapeutic potential in preclinical T-cell therapy for cancer. Collectively, NKG7 is emerging as a promising biomarker and therapeutic addition to T cell–based immunotherapies.

The differentiation of naive CD8+ T cells into effector or memory populations requires dynamic remodeling of cellular metabolism and proteome composition. In a recent study published in Nature Immunology, Sinclair et al offer critical insights into the role of autophagy, particularly mitophagy, in regulating these processes during CD8+ T cell differentiation. Autophagy, a conserved catabolic mechanism, is traditionally associated with cellular homeostasis and survival during nutrient deprivation. In contrast, Sinclair et al reveal that, in the immune system, autophagy is not simply a survival mechanism but a fine-tuned regulator of CD8+ T cell metabolism and function, fine-tuning CD8+ T cell effector vs quiescence choices.

ABSTRACT Lung cancer is the leading cause of cancer-related deaths worldwide and, despite treatment advances, immune suppression remains an obstacle to effective therapy. Effector CD4 + T cells (CD4 + Teffs) are critical for antitumor immunity, but their function is often inhibited by regulatory T cells (Tregs), which accumulate in lung tumors and perform suppressive functions through multiple mechanisms. This suppression leads to tumor progression and poor patient outcomes. However, the mechanisms underlying Treg-mediated suppression are not fully understood. Here, we identify the extracellular ATP receptor P2RX7 as a key regulator of Treg function in lung tumors. Using a murine lung cancer model induced by Lewis lung carcinoma cells, we demonstrate that P2RX7 enhances the suppressive capacity of tumor-infiltrating Tregs, promoting tumor growth. In T cell-specific P2RX7-KO mice, reduced Treg infiltration was accompanied by increased CD4 + Teff accumulation and improved tumor control. Treg-specific P2RX7-KO mice exhibit reduced tumor growth, confirming a cell-intrinsic role of P2RX7 in Tregs. Suppression assays revealed that tumor-infiltrating WT Tregs have greater suppressive activity compared to P2RX7-KO Tregs, which failed to inhibit type 1 and Tfh-like responses. This was associated with increased tumor-specific IgG production by lung B cells in P2RX7-KO mice. We also observed that WT Tregs express higher levels of the immunosuppressive surface molecule CTLA-4 when compared to P2RX7-KO Tregs. In summary, we show that P2RX7 expression on Tregs is essential for their suppressive function in lung cancer, and targeting of P2RX7 may constitute a novel strategy to improve lung cancer treatment by alleviating Treg-mediated immune suppression.

Abstract Durable T cell immunity against cancer depends on the continual replenishment of effector CD8+ T cells. Thymic output has been correlated with favorable prognosis in cancer patients across a range of ages, suggesting that the thymus is an important source for replenishing T cells capable of controlling cancer progression. However, the effector potential of thymic mature CD8+ T cells and their regulation have not been clearly defined. In this study, we identified the ability of thymic single positive CD8+ T cells to gain effector potential after thymic selection, but they are subject to the regulation of PD-1. We found a previously undisclosed role of PD-1 in limiting both the cytotoxic and exhaustion potential of thymic and peripheral CD8+ T cells. Our results show that although PD-1 inhibition facilitates the expansion of effector CD8+ T cells, effector CD8+ cells gradually lose their antitumor activity within tumor tissues due to advanced exhaustion in the absence of PD-1. Thus, although the preset effector potential in thymic mature CD8+ T cells allows them to rapidly respond to malignant cells in the periphery, PD-1, as a checkpoint, is embedded in the thymic mature CD8+ T cells after positive selection to balance their effector function from exaggeration and exhaustion. Therefore, we propose that a strategy capable of upholding the cytotoxic capacity and avoiding exhaustion of CD8+ T cells during the early stages of PD-1 inhibition therapy is needed to achieve durable antitumor immunity.

Abstract CD8+ T-cell responses are influenced by ion abundance, which can widely vary within the tumor microenvironment. In this issue, Collier and colleagues investigated how intracellular versus extracellular potassium ion (K+) regulates intratumoral CD8+ T cells. They show that, while excessive extracellular K+ induces exhaustion, intracellular K+ is needed for protection from dysfunction. This work shows additional evidence that the regulation of CD8+ T-cell responses depends on a fine balance between intracellular and extracellular metabolite levels. See related article by Collier et al., p. 36 (2) .

The activation and function of T cells is fundamental for the control of infectious diseases and cancer, and conversely can mediate several autoimmune diseases. Among the signaling pathways leading to T cell activation and function, the sensing of extracellular adenosine triphosphate (eATP) has been recently appreciated as an important component. Through a plethora of purinergic receptors, most prominently P2RX7, eATP sensing can induce a wide variety of processes in T cells, such as proliferation, subset differentiation, survival, or cell death. The downstream roles of eATP sensing can vary according to (a) the T cell subset, (b) the tissue where T cells are, and (c) the time after antigen exposure. In this mini-review, we revisit the recent findings on how eATP signaling pathways regulate T-cell immune responses and posit important unanswered questions on this field.

Abstract Expression of the purinergic receptor P2RX7 by CD8+ T cells promotes the generation of memory populations following acute infections. However, data suggest that P2RX7 may limit the efficacy of antitumor responses. Herein, we show that P2RX7 is beneficial for optimal melanoma control in a mouse CD8+ T-cell adoptive transfer model. Tumor-specific P2rx7–/– CD8+ T cells exhibited impaired mitochondrial maintenance and function but did not display signs of overt exhaustion early in the antitumor response. However, as the tumor burden increased, the relative frequency of P2RX7-deficient CD8+ T cells declined within the tumor; this correlated with reduced proliferation, increased apoptosis, and mitochondrial dysfunction. Extending these studies, we found that the transient in vitro stimulation of P2RX7 using the ATP analogue BzATP led to enhanced B16 melanoma control by CD8+ T cells. These findings are in keeping with the concept that extracellular ATP (eATP) sensing by P2RX7 on CD8+ T cells is required for their ability to efficiently eliminate tumors by promoting mitochondrial fitness and underscore the potential for P2RX7 stimulation as a novel therapeutic treatment to enhance tumor immunotherapy.

AbstractIdentifying factors secreted by multiple myeloma (MM) cells that may contribute to MM tumor biology and progression is of the utmost importance. In this study, hepatoma-derived growth factor (HDGF) was identified as a protein present in extracellular vesicles (EVs) released from human MM cell lines (HMCLs). Investigation of the role of HDGF in MM cell biology revealed lower proliferation of HMCLs following HDGF knockdown and AKT phosphorylation following the addition of exogenous HDGF. Metabolic analysis demonstrated that HDGF enhances the already high glycolytic levels of HMCLs and significantly lowers mitochondrial respiration, indicating that HDGF may play a role in myeloma cell survival and/or act in a paracrine manner on cells in the bone marrow (BM) tumor microenvironment (ME). Indeed, HDGF polarizes macrophages to an M1-like phenotype and phenotypically alters naïve CD14+ monocytes to resemble myeloid-derived suppressor cells which are functionally suppressive. In summary, HDGF is a novel factor in MM biology and may function to both maintain MM cell viability as well as modify the tumor ME.