InVivoMAb anti-mouse PD-1 (CD279)

Hepatocellular carcinoma (HCC) evades anti-PD-1 immunotherapy via an immunosuppressive microenvironment, where lactate links metabolic reprogramming to epigenetic regulation. We analyzed pan-lysine lactylation and H3K18 lactylation (H3K18la) in 89 HCC patient pairs, and validated functional mechanisms using glycolysis inhibition, HCC-CD8+ T cell co-cultures, and rescue assays. In vivo efficacy was assessed in subcutaneous and orthotopic HCC mouse models. H3K18la levels were elevated in HCC, correlating with advanced staging and poor prognosis. Lactate induced H3K18la to transcriptionally upregulate KIF20A, which stabilized the c-Myc/PD-L1 axis and suppressed cytotoxic T cell function. Combined glycolysis inhibition and anti-PD-1 therapy reversed this immunosuppression and synergistically inhibited tumor growth. This study identifies an H3K18la-KIF20A/PD-L1 axis as a key metabolic-epigenetic checkpoint, highlighting glycolysis targeting as a promising strategy to enhance anti-PD-1 responses in HCC.

T cell-based immunotherapies have improved outcomes in lung adenocarcinoma (LUAD), yet many patients develop primary or acquired resistance. Tumor-intrinsic mechanisms that suppress CD8+ T cell function remain incompletely understood.

Bone is the most common and preferential site for breast cancer metastasis. Upon dissemination to the bone, breast cancer cells engraft into multiple niches, but it is unclear whether there are region-specific differences that may drive breast cancer progression in bone. We used a proteomic digital spatial profiling (DSP) approach to investigate which proliferation, cell death, and immune-related markers and pathways are enriched in immune and cancer cells residing 1) in the bone marrow or 2) along the endosteal surface, in an E0771, α-PD-1 treated pre-clinical model of breast cancer bone metastasis. We selected morphological markers to identify breast cancer cells and immune cells and applied a multiplexed set of probes targeting >70 proteins to characterize breast cancer and immune cell signaling in the marrow and endosteal regions using a DSP platform. We found multiple immune suppressive markers were enriched in the endosteum, including Foxp3, CD163, CD27, Pd-1, and Pd-l1, while proliferation markers were enriched in tumor cells in the marrow, including p38 Mapk, pan-Ras, Mek1, and phospho-Erk1/2. These findings shed light on the niche-specific proteins and pathways that are activated in breast cancer bone metastases and establish a user-friendly highly multiplexed approach for spatial proteomics in pre-clinical models of bone metastasis.

Bone marrow adipocytes are known to have a critical role within the bone marrow niche. However, our understanding of bone marrow adipose tissue expansion with obesity and the role it plays in immune cell regulation and osteoclastogenesis is limited. Here, we showed the expansion of bone marrow adipocytes promoted osteoclast differentiation and subsequently led to obesity-related trabecular and cortical bone loss through a stimulatory effect of the PD-1/PD-L1 axis. Bone marrow adipocytes isolated from obese mice had increased Mcp-1 expression, a key regulator of osteoclastogenesis and myeloid cell accumulation. With the increase in bone marrow adipose tissue-derived Mcp-1, we found an increase in the number of PD-L1+ myeloid cells. While these cells inhibited activated T-cells, we found evidence of a stimulatory osteoclastogenic effect of PD-L1+ myeloid cells on PD-1-expressing osteoclast precursors. The inhibition of PD-1/PD-L1 signaling during early osteoclastogenesis prevented myeloid cell commitment and resulted in decreased cell fusion, supporting the role of PD-1/PD-L1 signaling in osteoclastogenesis. Using a bone marrow adipocyte depletion mouse model (BMAd-Pparg KO), we demonstrated that obese BMAd-Pparg KO mice had a reduced number of bone marrow PD-L1+ myeloid cells, accompanied by a decrease in PD-1+ osteoclast precursors. The reduction in these precursors resulted in fewer osteoclasts, subsequently leading to improved trabecular bone volume. Since osteoclasts are myeloid cell-derived, these results suggest that bone marrow adipocytes are critical for the commitment and differentiation of myeloid cells into osteoclasts. Targeting bone marrow adipogenesis could ameliorate enhanced osteoclastogenesis and provide a novel approach to treat obesity-related bone loss. Obesity-induced expansion of BM adipocytes leads to PD-1/PD-L1-driven osteoclastogenesis and subsequent bone loss in obese, HFD-fed (OB-HFD) mice. After 12 weeks on a HFD, OB-HFD mice had a significant increase in BM adiposity and BMAT-derived Mcp-1 expression. The increase in BMAT-specific Mcp-1 expression was coupled with an increase in PD-1+ osteoclast (OC) precursors and PD-L1+ myeloid cells. In the context of obesity, the PD-1/PD-L1 axis has a stimulatory effect that enhances osteoclastogenesis and leads to trabecular and cortical bone loss. By depleting BM adipocytes with obesity, BMAT-derived Mcp-1 expression was decreased, as well as a decrease in PD-1+ OC precursors and PD-L1+ myeloid cells. This prevented obesity-related trabecular bone loss. Overall, this work demonstrated a strong correlation between BMAT expansion and PD-1/PD-L1-driven osteoclastogenesis as a mechanism for obesity-induced bone loss. (This image was created using BioRender).