The involvement of tumour-resident memory T (TRM) cells in responses to immune checkpoint inhibitors remains unclear. Here, we show that while CD103+CD8 TRM cells are involved in response to PD-1 blockade, CD49a+CD4 TRM cells are required for the response to anti-CTLA-4. Using preclinical mouse models, we demonstrate that the benefits of anti-PD-1 treatment are compromised in animals challenged with anti-CD8 and anti-CD103 blocking antibodies. By contrast, the benefits of anti-CTLA-4 are decreased by anti-CD4 and anti-CD49a neutralizing antibodies. Single-cell RNA sequencing on tumour-infiltrating T-lymphocytes (TIL) reveals a CD49a+CD4 TRM signature, enriched in Ctla-4 transcripts, exacerbated upon anti-CTLA-4. CTLA-4 blockade expands CD49a+CD4 TRM cells and increases tumour-specific CD4-TIL-mediated cytotoxicity. A CD49a+CD4 TRM signature enriched in CTLA-4 and cytotoxicity-linked transcripts is also identified in human TILs. Multiplex immunohistochemistry in a cohort of anti-CTLA-4-plus-anti-PD-1-treated melanomas reveals an increase in CD49a+CD4 T-cell density in pre-treatment tumours, which correlates with higher rates of patient progression-free survival. Thus, CD49a+CD4 TRM cells may correspond to a predictive biomarker of response to combined immunotherapy.
© 2025. The Author(s).

NKp46 is a critical regulator of natural killer (NK) cell immunity, but its function in non-NK innate immune cells remains unclear. Here, we show that NKp46 is indispensable for expressing IL-2 receptor-α (IL-2Rα) by non-NK liver-resident type-1 innate lymphoid cells (ILC1s). Deletion of NKp46 reduces IL-2Rα on ILC1s by downregulating NF-κB signaling, thus impairing ILC1 proliferation and cytotoxicity in vitro and in vivo. The binding of anti-NKp46 antibody to NKp46 triggers the activation of NF-κB, the expression of IL-2Rα, interferon-γ (IFN-γ), tumor necrosis factor (TNF), proliferation, and cytotoxicity. Functionally, NKp46 expressed on mouse ILC1s interacts with tumor cells through cell-cell contact, increasing ILC1 production of IFN-γ and TNF, and enhancing cytotoxicity. In a mouse model of acute myeloid leukemia, deletion of NKp46 impairs the ability of ILC1s to control tumor growth and reduces survival. This can be reversed by injecting NKp46+ ILC1s into NKp46 knock-out mice. Human NKp46+ ILC1s exhibit stronger cytokine production and cytotoxicity than their NKp46- counterparts, suggesting that NKp46 plays a similar role in humans. These findings identify an NKp46-NF-κB-IL-2Rα axis and suggest that activating NKp46 with an anti-NKp46 antibody may provide a potential strategy for anti-tumor innate immunity.
© 2025. The Author(s).

The increasing use of anti-programmed cell death 1 (PD-1) immune checkpoint blockade has led to the emergence of immune-related adverse events (irAEs), including dysfunction of the submandibular gland (SMG). In this study, we investigated the immunoregulatory mechanism contributing to the susceptibility of the SMG to irAEs. We found that the SMGs of PD-1-deficient mice and anti-programmed cell death ligand 1 (PD-L1)-treated mice harbor an expanded population of CD8+ T cells. We demonstrate that natural killer (NK) cells expressing PD-L1 tightly regulate CD8+ T cells in the SMG. When this immunoregulation is disrupted, CD8+ T cells clonally expand and acquire a unique transcriptional profile consistent with T cell receptor (TCR) activation. These clonally expanded cells phenotypically overlapped with cytotoxic GzmK+ CD8+ T autoimmune cells identified in patients with primary Sjögren's syndrome. Understanding how NK cells modulate CD8+ T cell activity in the SMG opens new avenues for preventing irAEs in patients undergoing checkpoint blockade therapies.

Sarcoidosis is a multiorgan granulomatous disease that lacks diagnostic biomarkers and targeted treatments. Using blood and skin from patients with sarcoid and non-sarcoid skin granulomas, we discovered that skin granulomas from different diseases exhibit unique immune cell recruitment and molecular signatures. Sarcoid skin granulomas were specifically enriched for type 1 innate lymphoid cells (ILC1s) and B cells and exhibited molecular programs associated with formation of mature tertiary lymphoid structures (TLSs), including increased CXCL12/CXCR4 signaling. Lung sarcoidosis granulomas also displayed similar immune cell recruitment. Thus, granuloma formation was not a generic molecular response. In addition to tissue-specific effects, patients with sarcoidosis exhibited an 8-fold increase in circulating ILC1s, which correlated with treatment status. Multiple immune cell types induced CXCL12/CXCR4 signaling in sarcoidosis, including Th1 T cells, macrophages, and ILCs. Mechanistically, CXCR4 inhibition reduced sarcoidosis-activated immune cell migration, and targeting CXCR4 or total ILCs attenuated granuloma formation in a noninfectious mouse model. Taken together, our results show that ILC1s are a tissue and circulating biomarker that distinguishes sarcoidosis from other skin granulomatous diseases. Repurposing existing CXCR4 inhibitors may offer a new targeted treatment for this devastating disease.

CD8+ T cells provide host protection against pathogens by differentiating into distinct effector and memory cell subsets, but how chromatin is site-specifically remodeled during their differentiation is unclear. Due to its critical role in regulating chromatin and enhancer accessibility through its nucleosome remodeling activities, we investigated the role of the canonical BAF (cBAF) chromatin remodeling complex in antiviral CD8+ T cells during infection. ARID1A, a subunit of cBAF, was recruited early after activation and established de novo open chromatin regions (OCRs) at enhancers. Arid1a deficiency impaired the opening of thousands of activation-induced enhancers, leading to loss of TF binding, dysregulated proliferation and gene expression, and failure to undergo terminal effector differentiation. Although Arid1a was dispensable for circulating memory cell formation, tissue-resident memory (Trm) formation was strongly impaired. Thus, cBAF governs the enhancer landscape of activated CD8+ T cells that orchestrates TF recruitment and activity and the acquisition of specific effector and memory differentiation states.
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