Secreted proteins mediate intercellular and inter-organ communication and are essential for coordinating physiological processes across tissues. Advances in proteomics and proximity labeling have greatly expanded the catalog of circulating secreted factors; however, for many of these molecules, their cognate receptors and mechanisms of action remain unknown. This lack of receptor annotation represents a major bottleneck in understanding systemic signaling networks and translating secretome discoveries into biological insights. In this review, we summarize and evaluate the strengths and limitations of current strategies for deorphanizing secreted proteins, including 1) biochemical approaches such as affinity purification–mass spectrometry and crosslinking-based receptor capture, 2) genetic screening strategies in both in vivo and in vitro systems, including RNA interference and Clustered Regularly-Interspaced Short Palindromic Repeats (CRISPR)-based perturbation and activation platforms, and 3) computational frameworks based on AI-driven protein structure modeling. Finally, we outline future directions aimed at accelerating ligand–receptor identification, including multiplexed screening platforms, approaches to improve sensitivity for low-affinity interactions, synthetic biology tools that convert transient binding events into stable readouts, and integration with single-cell and spatial transcriptomic technologies. Together, these advances provide a roadmap for transforming classical ligand deorphanization into a scalable, context-aware framework for decoding inter-organ communication.

Lymphatic endothelial cells (LECs) and the lymphatic vasculature have evolved from being viewed as passive conduits for fluid drainage and metastatic dissemination to active, dynamic regulators of inflammation and tumor immunity. In solid tumors, both tumor-associated and lymph node (LN)–resident LECs engage in complex interactions with their environment to orchestrate immune processes, including antigen transport and presentation to T cells, leukocyte recruitment and trafficking via chemokine gradients, and local immune modulation through the expression of co-inhibitory ligands such as programmed death-ligand 1 (PD-L1). These multifaceted roles enable LECs to either amplify effector responses or induce tolerance, profoundly influencing the efficacy of cancer immunotherapies depending on their activation state, tissue context, and molecular programming. This minireview synthesizes and discusses recent advances in tumor lymphangiogenesis, the role of LECs and their intensive crosstalk with the immune compartments, in the coordination of anti-tumor immune responses, with particular focus on LEC-autophagy as a lipid metabolic checkpoint controlling lymph node T cell egress, and its far-reaching implications for optimizing immunotherapy outcomes in solid tumors.

Caspase-2 is a key genome-surveillance protease that functions to kill or arrest cells with abnormal chromosome content, via PIDDosome-dependent and -independent mechanisms. However, this surveillance function presents a biological paradox in the liver, where physiological polyploidy, is essential for organogenesis, genomic buffering and adaptive stress responses to maintain liver homeostasis. While short-term caspase-2 loss promotes adaptive polyploidy, our recent work demonstrates that prolonged caspase-2 deficiency drives pathogenic hyperploidy, fuelling chronic inflammation, and increased age-associated hepatocellular carcinoma in mice. These findings underscore the need for tight ploidy control in the maintenance of liver homeostasis. They also highlight potential risks for therapeutic targeting of caspase-2 in fatty liver disease and suggest that pathways governing lipid metabolism also influence long-term tumour surveillance mechanisms. This perspective discusses caspase-2 as a guardian of hepatic genome integrity, and the dual, context-dependent roles of polyploidy in liver physiology and metabolic liver disease.

Background: Cystic fibrosis (CF) is a progressive genetic disease characterized by defective ion transport, mucus accumulation, chronic infection, and inflammation that drive airway damage and ultimately end-stage lung failure. Previous studies show that high levels of proteolytic enzymes in the sputum of CF patients correlate with declining lung function, but the related effects on distal lung extracellular matrix (ECM) and immune responses are unclear.

Methods: To address this gap, induced pluripotent stem cell (iPSC) lines from healthy donors and CF patients were differentiated into macrophages, and stimulated with lipopolysaccharide (LPS) to compare their inflammatory responses. Bulk RNA sequencing, functional assays, and secreted protein profiling revealed key differences between healthy and CF-derived macrophages, providing insight into how these cells may contribute to inflammatory responses in CF patients. Further, human lung ECM from distal CF lung tissue was isolated, used to generate ECM biomaterials, and combined with iPSC-derived macrophages from healthy and CF donors in vitro. Macrophage phenotype was evaluated through cytokine profiling and RNA sequencing.

Results: CF macrophage inflammation was dysregulated, with elevated baseline IL-8, IL-18, and MCP-1 expression, and a blunted inflammatory response to CF ECM compared to healthy macrophages. By using CF ECM and healthy macrophages, we characterized how healthy cells may be altered in a persistent CF milieu after anticipated CFTR modulator therapy.

Conclusion: These findings reveal altered innate immune behavior in CF and demonstrate the utility of iPSC-derived macrophages for modeling extrinsic immune-ECM interactions in disease.