Multiomics reveal the central role of pentose phosphate pathway in resident thymic macrophages to cope with efferocytosis-associated stress.

Tissue-resident macrophages (TRMs) are heterogeneous cell populations found throughout the body. Depending on their location, they perform diverse functions maintaining tissue homeostasis and providing immune surveillance. To survive and function within, TRMs adapt metabolically to the distinct microenvironments. However, little is known about the metabolic signatures of TRMs. The thymus provides a nurturing milieu for developing thymocytes yet efficiently removes those that fail the selection, relying on the resident thymic macrophages (TMφs). This study harnesses multiomics analyses to characterize TMφs and unveils their metabolic features. We find that the pentose phosphate pathway (PPP) is preferentially activated in TMφs, responding to the reduction-oxidation demands associated with the efferocytosis of dying thymocytes. The blockade of PPP in Mφs leads to decreased efferocytosis, which can be rescued by reactive oxygen species (ROS) scavengers. Our study reveals the key role of the PPP in TMφs and underscores the importance of metabolic adaptation in supporting Mφ efferocytosis.

Exploration of the niche effect on tumor satellite budding of head and neck cancer with biomimicking modeling.

Dissemination is an ominous feature of cancer to cause poor prognosis. Formation of tumor satellites is the first step, which is closely interdependent on the factors originating from surrounding niche. Because of lacking appropriate modeling, most studies focusing on cancer-environmental interaction depend on the static pathological analyses of specimens. Using the biomimicking system capable of inducing tumor satellite formation in vitro, the niche factors were explored for their influence on cancer budding. Our results demonstrated the real-time dynamic of tumor satellite formation of head and neck squamous cell carcinoma (HNSCC) that was significantly affected by these niche factors. Hypoxia reduced the incidence and migratory distance of HNSCC tumor satellites via decreasing the nuclear localization of intracellular domain of E-cadherin (iEcad) and ß-catenin. Three-dimensional (3D) architecture and collagen were essential for mediating hypoxia effects on nuclear translocation and signaling transduction of iEcad and ß-catenin in the HNSCC cells. The findings were further confirmed by the compatible in vivo findings of the cancer specimens. This approach revealed the effects of oxygen and extracellular matrices on tumor satellites. The cellular behaviors and molecular dynamics were along a phenotypic spectrum that conferred unique change for specific cancer populations in response to the altered microenvironment. The current study provides a platform to recapitulate the process of cancer budding, and a way to investigate the mutual interaction between the cancer cells and their surrounding microenvironment.

Equilibrative Nucleoside Transporter 3 Regulates T Cell Homeostasis by Coordinating Lysosomal Function with Nucleoside Availability.

T cells are a versatile immune cell population responding to challenges by differentiation and proliferation followed by contraction and memory formation. Dynamic metabolic reprogramming is essential for T cells to meet the biosynthetic needs and the reutilization of biomolecules, processes that require active participation of metabolite transporters. Here, we show that equilibrative nucleoside transporter 3 (ENT3) is highly expressed in peripheral T cells and has a key role in maintaining T cell homeostasis by supporting the proliferation and survival of T cells. ENT3 deficiency leads to an enlarged and disturbed lysosomal compartment, resulting in accumulation of surplus mitochondria, elevation of intracellular reactive oxygen species, and DNA damage in T cells. Our results identify ENT3 as a vital metabolite transporter that supports T cell homeostasis and activation by regulating lysosomal integrity and the availability of nucleosides. Moreover, we uncovered that T cell lysosomes are an important source of salvaged metabolites for survival and proliferation.