Network analysis of large-scale ImmGen and Tabula Muris datasets highlights metabolic diversity of tissue mononuclear phagocytes

Multifaceted cancer alleviation by cowpea mosaic virus in a bioprinted ovarian cancer peritoneal spheroid model

Ovarian cancer (OvCa) is a leading cause of mortality among gynecological malignancies and usually manifests as intraperitoneal spheroids that generate metastases, ascites, and an immunosuppressive tumor microenvironment. In this study, we explore the immunomodulatory properties of cowpea mosaic virus (CPMV) as an adjuvant immunotherapeutic agent using an in vitro model of OvCa peritoneal spheroids. Previous findings highlighted the potent efficacy of intratumoral CPMV against OvCa in mouse tumor models. Leveraging the precision control over material deposition and cell patterning afforded by digital-light-processing (DLP) based bioprinting, we constructed OvCa-macrophage spheroids to mimic peritoneal spheroids using gelatin methacrylate (GelMA), a collagen-derived photopolymerizable biomaterial to mimic the extracellular matrix. Following CPMV treatment, bioprinted spheroids exhibited inhibited OvCa progression mediated by macrophage activation. Our analysis indicates that CPMV regulates and activates macrophage to both induce OvCa cell killing and restore normal cell-cell junctions. This study deepened our understanding of the mechanism of CPMV intratumoral immunotherapy in the setting of OvCa. This study also highlights the potential of studying immunotherapies using high throughput tissue models via DLP bioprinting.

Liver macrophages revisited: The expanding universe of versatile responses in a spatiotemporal context

The liver is a vital organ that continuously adapts to a wide and dynamic diversity of self-antigens and xenobiotics. This involves the active contribution of immune cells, particularly by the liver-resident macrophages, the Kupffer cells (KCs), which exert a variety of central functions in liver homeostasis and disease. As such, KCs interact with their microenvironment to shape the hepatic cellular landscape, control gut-derived signal integration, and modulate metabolism. On injury, the rapid recruitment of bone marrow monocyte-derived macrophages alters this status quo and, when unrestrained, drastically compromises liver homeostasis, immune surveillance, and tissue organization. Several factors determine the functional roles of liver macrophages in these processes, such as their ontogeny, activation/polarization profile and, importantly, spatial distribution within the liver. Loss of tolerance and adaptability of the hepatic immune environment may result in persistent inflammation, hepatic fibrosis, cirrhosis, and a tumorigenic niche promoting liver cancer. In this review, we aim at providing the most recent breakthroughs in our understanding of liver macrophage biology, particularly their diversity and adaptability in the hepatic spatiotemporal context, as well as on potential therapeutic interventions that may hold the key to tackling remaining clinical challenges of varying etiologies in hepatology.

Metabolic homeostasis of tissue macrophages across the lifespan

Macrophages are present in almost all organs. Apart from being immune sentinels, tissue-resident macrophages (TRMs) have organ-specific functions that require a specialized cellular metabolism to maintain homeostasis. In addition, organ-dependent metabolic adaptations of TRMs appear to be fundamentally distinct in homeostasis and in response to a challenge, such as infection or injury. Moreover, TRM function becomes aberrant with advancing age, contributing to inflammaging and organ deterioration, and a metabolic imbalance may underlie TRM immunosenescence. Here, we outline current understanding of the particular metabolic states of TRMs across organs and the relevance for their function. Moreover, we discuss the concomitant aging-related decline in metabolic plasticity and functions of TRMs, highlighting potential novel therapeutic avenues to promote healthy aging.

Defining solute carrier transporter signatures of murine immune cell subsets

Solute carrier (SLC) transporters are membrane-bound proteins that facilitate nutrient transport, and the movement across cellular membranes of various substrates ranging from ions to amino acids, metabolites and drugs. Recently, SLCs have gained increased attention due to their functional linkage to innate immunological processes such as the clearance of dead cells and anti-microbial defense. Further, the druggable nature of these transporters provides unique opportunities for improving outcomes in different immunological diseases. Although the SLCs represent the largest group of transporters and are often identified as significant hits in omics data sets, their role in immunology has been insufficiently explored. This is partly due to the absence of tools that allow identification of SLC expression in particular immune cell types and enable their comparison before embarking on functional studies. In this study, we used publicly available RNA-Seq data sets to analyze the transcriptome in adaptive and innate immune cells, focusing on differentially and highly expressed SLCs. This revealed several new insights: first, we identify differentially expressed SLC transcripts in phagocytes (macrophages, dendritic cells, and neutrophils) compared to adaptive immune cells; second, we identify new potential immune cell markers based on SLC expression; and third, we provide user-friendly online tools for researchers to explore SLC genes of interest (and the rest of the genes as well), in three-way comparative dot plots among immune cells. We expect this work to facilitate SLC research and comparative transcriptomic studies across different immune cells.

Angiocrine Signaling in Sinusoidal Health and Disease

Liver sinusoidal endothelial cells (LSECs) are key players in maintaining hepatic homeostasis. They also play crucial roles during liver injury by communicating with liver cell types as well as immune cells and promoting portal hypertension, fibrosis, and inflammation. Cutting-edge technology, such as single cell and spatial transcriptomics, have revealed the existence of distinct LSEC subpopulations with a clear zonation in the liver. The signals released by LSECs are commonly called "angiocrine signaling." In this review, we summarize the role of angiocrine signaling in health and disease, including zonation in healthy liver, regeneration, fibrosis, portal hypertension, nonalcoholic fatty liver disease, alcohol-associated liver disease, aging, drug-induced liver injury, and ischemia/reperfusion, as well as potential therapeutic advances. In conclusion, sinusoidal endotheliopathy is recognized in liver disease and promising preclinical studies are paving the path toward LSEC-specific pharmacotherapies.

Signaling is the pathway to macrophage function

Tissue and inflammatory contexts are well appreciated to shape macrophage function to promote health or disease. However, there has been minimal progress towards understanding how these contexts modify signaling-to-transcription networks. Integration of mechanistic modeling and data-driven approaches will be crucial for investigating how cell state impacts macrophage decision-making.

Systems Immunology Approaches to Metabolism

Over the last decade, immunometabolism has emerged as a novel interdisciplinary field of research and yielded significant fundamental insights into the regulation of immune responses. Multiple classical approaches to interrogate immunometabolism, including bulk metabolic profiling and analysis of metabolic regulator expression, paved the way to appreciating the physiological complexity of immunometabolic regulation in vivo. Studying immunometabolism at the systems level raised the need to transition towards the next-generation technology for metabolic profiling and analysis. Spatially resolved metabolic imaging and computational algorithms for multi-modal data integration are new approaches to connecting metabolism and immunity. In this review, we discuss recent studies that highlight the complex physiological interplay between immune responses and metabolism and give an overview of technological developments that bear the promise of capturing this complexity most directly and comprehensively.