实体瘤中高内皮微静脉 (HEV) 和三级淋巴结构 (TLS) 的存在与许多癌症类型的良好预后和对免疫检查点阻断 (ICB) 的更好反应相关。阐明瘤内 HEV 和 TLS 形成的分子机制及其对抗肿瘤反应的贡献可能有助于开发改进的治疗策略。淋巴毒素β受体 (LTβR) 信号传导是淋巴结器官发生的关键调节因子，可以与抗血管生成和 ICB 治疗相配合，以增强肿瘤相关的 HEV 形成。在这里，我们证明了 LTβR 信号通过多种机制调节肿瘤微环境，以促进抗肿瘤 T 细胞反应。通过激动性抗体治疗系统性激活 LTβR 通路，诱导肿瘤特异性 HEV 形成，上调 TLS 相关趋化因子的表达，并增强同基因肿瘤模型中的树突状细胞 (DC) 和 T 细胞浸润和激活。体外研究证实了 LTβR 激动剂对 DC 活化和成熟以及相关 DC 介导的 T 细胞活化的直接影响。单药LTβR激动剂治疗以CD8 ​​T细胞和HEV依赖性方式抑制同基因肿瘤生长，并且LTβR激动剂增强了抗PD-1和CAR T细胞疗法的抗肿瘤作用。对 TLS 诱导细胞因子的体内肿瘤筛选显示，LTβR 激动和淋巴毒素 α (LT⍺) 表达的组合促进了肿瘤内 TLS 的强烈诱导，并增强了肿瘤对抗 CTLA-4 治疗的反应。总的来说，这项研究强调了 LTβR 信号在调节肿瘤微环境中的关键功能，并可为未来基于 HEV/TLS 的癌症治疗策略提供信息。

The presence of high endothelial venules (HEV) and tertiary lymphoid structures (TLS) in solid tumors is correlated with favorable prognosis and better responses to immune-checkpoint blockade (ICB) in many cancer types. Elucidation of the molecular mechanisms underlying intratumoral HEV and TLS formation and their contribution to anti-tumor responses may facilitate development of improved treatment strategies. Lymphotoxin beta receptor (LTβR) signaling is a critical regulator of lymph node organogenesis and can cooperate with antiangiogenic and ICB treatment to augment tumor-associated HEV formation. Here, we demonstrated that LTβR signaling modulates the tumor microenvironment via multiple mechanisms to promote anti-tumor T cell responses. Systemic activation of the LTβR pathway via agonistic antibody treatment induced tumor-specific HEV formation, upregulated the expression of TLS-related chemokines, and enhanced dendritic cell (DC) and T cell infiltration and activation in syngeneic tumor models. In vitro studies confirmed direct effects of LTβR agonism on DC activation and maturation and associated DC-mediated T cell activation. Single agent LTβR agonist treatment inhibited syngeneic tumor growth in a CD8+ T cell- and HEV-dependent manner, and the LTβR agonist enhanced anti-tumor effects of anti-PD-1 and CAR T cell therapies. An in vivo tumor screen for TLS-inducing cytokines revealed that the combination of LTβR agonism and lymphotoxin alpha (LT⍺) expression promoted robust intratumoral TLS induction and enhanced tumor responses to anti-CTLA-4 treatment. Collectively, this study highlights crucial functions of LTβR signaling in modulating the tumor microenvironment and could inform future HEV/TLS-based strategies for cancer treatments.