Liver X receptors regulate natural killer T cell population and antitumor activity in the liver of mice

FAP-targeted radioligand therapy with 68Ga/177Lu-DOTA-2P(FAPI)2 enhance immunogenicity and synergize with PD-L1 inhibitors for improved antitumor efficacy

BACKGROUND

Fibroblast activation protein (FAP)-targeted radioligand therapy, with immunomodulatory effects, has shown efficacy in both preclinical and clinical studies. We recently reported on a novel dimeric FAP-targeting radiopharmaceutical, 68Ga/177Lu-DOTA-2P(FAPI)2, which demonstrated increased tumor uptake and prolonged retention in various cancers. However, further exploration is required to understand the therapeutic efficacy and underlying mechanisms of combining 68Ga/177Lu-DOTA-2P(FAPI)2 radioligand therapy with PD-1/PD-L1 immunotherapy.

METHODS

Regarding the change in PD-L1 expression and DNA double-strand breaks induced by radiopharmaceuticals, CT26-FAP tumor cells were incubated with 68Ga and 177Lu labeled DOTA-2P(FAPI)2, respectively. Monotherapy with 68Ga-DOTA-2P(FAPI)2, 177Lu-DOTA-2P(FAPI)2, and PD-L1 immunotherapy as well as combination therapy (68Ga/177Lu-DOTA-2P(FAPI)2 and PD-L1 immunotherapy) were tested and evaluated to evaluate in vivo antitumor efficacy. Furthermore, immunohistochemical staining and single-cell RNA sequencing were used to analyze changes in the tumor microenvironment (TME) and elucidate the underlying mechanisms of action of this combination therapy.

RESULTS

Our findings indicated that FAP-targeting radiopharmaceuticals can induce DNA double-strand breaks and upregulate PD-L1 expression, with 177Lu-DOTA-2P(FAPI)2 proving to be more effective than 68Ga-DOTA-2P(FAPI)2. Both 68Ga-DOTA-2P(FAPI)2 and 177Lu-DOTA-2P(FAPI)2 radiopharmaceuticals significantly improved therapeutic outcomes when combined with anti-PD-L1 monoclonal antibody (αPD-L1 mAb). Notably, the combination of 177Lu-DOTA-2P(FAPI)2 with αPD-L1 mAb immunotherapy eliminated tumors in mouse models. Mice treated with this regimen not only exhibited exceptional responses to the initial immune checkpoint inhibitor therapy but also showed 100% tumor rejection on subsequent tumor cell re-inoculation. Further mechanistic studies have shown that 177Lu-DOTA-2P(FAPI)2 combined with αPD-L1 mAb can reprogram the TME, enhancing antitumor intercellular communication, which activates antitumor-related intercellular contacts such as FasL-Fas interactions between T cells and NK cells with tumor cells and increasing the proportion of infiltrating CD8+ T-cells while reducing regulatory T cells and inhibiting tumor progression. Our research also demonstrates that mature neutrophils play a role in enhancing the efficacy of the combined therapy, as shown in neutrophil-blocking experiments.

CONCLUSIONS

Our study robustly advocates for use of FAP-targeting radiopharmaceuticals, particularly 177Lu-DOTA-2P(FAPI)2, alongside immunotherapy in treating FAP-positive tumors. This combination therapy transforms the TME and enables a translatable approach to increasing the sensitivity to PD-1/PD-L1 immunotherapy, leading to improved complete remission rates and extended overall survival.

Theoretical framework and emerging challenges of lipid metabolism in cancer

Elevated lipid metabolism is one of hallmarks of malignant tumors. Lipids not only serve as essential structural components of biological membranes but also provide energy and substrates for the proliferation of cancer cells and tumor growth. Cancer cells meet their lipid needs by coordinating the processes of lipid absorption, synthesis, transport, storage, and catabolism. As research in this area continues to deepen, numerous new discoveries have emerged, making it crucial for scientists to stay informed about the developments of cancer lipid metabolism. In this review, we first discuss relevant concepts and theories or assumptions that help us understand the lipid metabolism and -based cancer therapies. We then systematically summarize the latest advancements in lipid metabolism including new mechanisms, novel targets, and up-to-date pre-clinical and clinical investigations of anti-cancer treatment with lipid metabolism targeted drugs. Finally, we emphasize emerging research directions and therapeutic strategies, and discuss future prospective and emerging challenges. This review aims to provide the latest insights and guidance for research in the field of cancer lipid metabolism.

Immunology of bile acids regulated receptors

Bile acids are steroids formed at the interface of host metabolism and intestinal microbiota. While primary bile acids are generated in the liver from cholesterol metabolism, secondary bile acids represent the products of microbial enzymes. Close to 100 different enzymatic modifications of bile acids structures occur in the human intestine and clinically guided metagenomic and metabolomic analyses have led to the identification of an extraordinary number of novel metabolites. These chemical mediators make an essential contribution to the composition and function of the postbiota, participating to the bidirectional communications of the intestinal microbiota with the host and contributing to the architecture of intestinal-liver and -brain and -endocrine axes. Bile acids exert their function by binding to a group of cell membrane and nuclear receptors collectively known as bile acid-regulated receptors (BARRs), expressed in monocytes, tissue-resident macrophages, CD4+ T effector cells, including Th17, T regulatory cells, dendritic cells and type 3 of intestinal lymphoid cells and NKT cells, highlighting their role in immune regulation. In this review we report on how bile acids and their metabolitesmodulate the immune system in inflammations and cancers and could be exploiting for developing novel therapeutic approaches in these disorders.

Research status and hotspots on the mechanisms of liver X receptor in cancer progression: A bibliometric analysis

BACKGROUND

The mechanism of liver X receptor in cancer has been gradually revealed in recent years. This study is committed to analyzing the current research status of the mechanism of liver × receptor in cancer progression by using bibliometric methods and to explore the development trend of liver × receptor related research in the future, in order to provide some reference for further exploration in this field.

METHODS

The Web of Science core collection database was used to carry out the original data retrieval. Excel software was used for data statistics. Vosviewer and CiteSpace software were used to analyze the publication situation, cooperation network, reference co-citation, keyword and term co-occurrence, term bursts, and cluster analysis, and draw visual maps.

RESULTS

A total of 631 publications meeting the research criteria were included by December 2022, with an average of 32.5 citations per paper. The main research fields were molecular biology, oncology and cell biology, and the papers were mainly published in journals about molecular, biology and immunology. Cell is the journal with the highest citation. The United States is the most influential country, the University of California, Los Angeles is the main research institution, and Gustafsson, Jan-ake is the author with the highest output. In reference co-citation clustering, cluster#2 "cancer development" is the main cluster, and the period from 2014 to 2018 is an important stage of relevant theoretical progress. "Tumor microenvironment" with high burst and novelty became the most noteworthy term in term burst.

CONCLUSION

Using bibliometric methods to reveal the current status of LXR and cancer mechanisms, and making predictions of possible future hotspots based on the analysis of the current situation, the translation of LXR anti-cancer research to clinical applications, the impact on the tumor microenvironment as a whole and more immune pathways, and the formation of a systematic cognition of the effects of more cancer cell lines and oncogenic signaling crosstalk, which is a possible direction for future research.

Role of Brain Liver X Receptor in Parkinson's Disease: Hidden Treasure and Emerging Opportunities

Parkinson's disease (PD) is a neurodegenerative disease due to the degeneration of dopaminergic neurons (DNs) in the substantia nigra (SN). The liver X receptor (LXR) is involved in different neurodegenerative diseases. Therefore, the objective of the present review was to clarify the possible role of LXR in PD neuropathology. LXRs are the most common nuclear receptors of transcription factors that regulate cholesterol metabolism and have pleiotropic effects, including anti-inflammatory effects and reducing intracellular cholesterol accumulation. LXRs are highly expressed in the adult brain and act as endogenous sensors for intracellular cholesterol. LXRs have neuroprotective effects against the development of neuroinflammation in different neurodegenerative diseases by inhibiting the expression of pro-inflammatory cytokines. LXRs play an essential role in mitigating PD neuropathology by reducing the expression of inflammatory signaling pathways, neuroinflammation, oxidative stress, mitochondrial dysfunction, and enhancement of BDNF signaling.In conclusion, LXRs, through regulating brain cholesterol homeostasis, may be effectual in PD. Also, inhibition of node-like receptor pyrin 3 (NLRP3) inflammasome and nuclear factor kappa B (NF-κB) by LXRs could effectively prevent neuroinflammation in PD. Taken together, LXRs play a crucial role in PD neuropathology by inhibiting neuroinflammation and associated degeneration of DNs.

Infections, Reactions of Natural Killer T Cells and Natural Killer Cells, and Kidney Injury

Natural killer T (NKT) cells and NK cells are representative innate immune cells that perform antitumor and antimicrobial functions. The involvement of these cells in various renal diseases, including acute kidney injury (AKI), has recently become evident. Murine NKT cells are activated and cause AKI in response to various stimuli, such as their specific ligand, cytokines, and bacterial components. Both renal vascular endothelial cell injury (via the perforin-mediated pathway) and tubular epithelial cell injury (via the tumor necrosis factor-alpha/Fas ligand pathway) are independently involved in the pathogenesis of AKI. NK cells complement the functions of NKT cells, thereby contributing to the development of infection-associated AKI. Human CD56⁺ T cells, which are a functional counterpart of murine NKT cells, as well as a subpopulation of CD56⁺ NK cells, strongly damage intrinsic renal cells in vitro upon their activation, possibly through mechanisms similar to those in mice. These cells are also thought to be involved in the acute exacerbation of pre-existing glomerulonephritis triggered by infection in humans, and their roles in sepsis-associated AKI are currently under investigation. In this review, we will provide an overview of the recent advances in the understanding of the association among infections, NKT and NK cells, and kidney injury, which is much more profound than previously considered. The important role of liver macrophages in the activation of NKT cells will also be introduced.