Macrophage STING signaling promotes NK cell to suppress colorectal cancer liver metastasis via 4-1BBL/4-1BB co-stimulation

CYP24A1 affected macrophage polarization through degradation of vitamin D as a candidate biomarker for ovarian cancer prognosis

Ovarian cancer (OC) is a fatal gynecological malignancy with a poor prognosis in which mitochondria-related genes are involved deeply. In this study, we aim to screen mitochondria-related genes that play a role in OC prognosis and investigate its effects. Through single-cell sequencing technology and bioinformatics analysis, including TCGA ovarian cancer data analysis, gene expression signature analysis (GES), immune infiltration analysis, Gene Ontology (GO) enrichment analysis, Gene Set Enrichment Analysis (GSEA), and Principal Component Analysis (PCA), our findings revealed that CYP24A1 regulated macrophage polarization through vitamin D (VD) degradation and served as a target gene for the second malignant subtype of OC through bioinformatics analyses. For further validation, the expression and function of CYP24A1 in OC cells was investigated. And the expression of CYP24A1 was much higher in carcinoma than in paracancerous tissue, whereas the VD content decreased in the OC cell lines with CYP24A1 overexpression. Moreover, macrophages were polarized towards M1 after the intervention of VD-treated OC cell lines and inhibited the malignant phenotypes of OC. However, the effect could be reversed by overexpressing CYP24A1, resulting in the polarization of M2 macrophages, thereby promoting tumor progression, as verified by constructing xenograft models in vitro. In conclusion, our findings suggested that CYP24A1 induced M2 macrophage polarization through interaction with VD, thus promoting the malignant progression of OC.

tBHQ mitigates fatty liver ischemia-reperfusion injury by activating Nrf2 to attenuate hepatocyte mitochondrial damage and macrophage STING activation

BACKGROUND

Liver ischemia-reperfusion (IR) injury is an inevitable pathophysiological process in various liver surgeries. Previous studies have found that IR injury is exacerbated in fatty liver due to significant hepatocellular damage and macrophage inflammatory activation, though the underlying mechanisms are not fully understood. In this study, we aim to explore the role and mechanism of Nrf2 (Nuclear factor erythroid 2-related factor 2) signaling in regulating hepatocellular damage and macrophage immune response in fatty liver IR injury.

METHODS

The study used high-fat diet-induced fatty liver mice to establish an IR model, alongside an in vitro co-culture system of primary hepatocytes and macrophages. This approach was used to examine mitochondrial dysfunction, oxidative stress, mitochondrial DNA (mtDNA) release, and activation of macrophage STING (Stimulator of interferon genes) signaling. We also conducted recovery verification using H-151 (a STING inhibitor) and tBHQ (an Nrf2 activator).

RESULTS

Compared to the control group, mice on a high-fat diet demonstrated more severe liver IR injury, as evidenced by increased histological damage, elevated liver enzyme levels, and heightened inflammatory markers. The HFD group showed significant oxidative stress and mitochondrial dysfunction and damage post-IR, as indicated by elevated levels of ROS and lipid peroxidation markers, and decreased antioxidant enzyme activity. Elevated mtDNA release from hepatocytes post-IR activated macrophage STING signaling, worsening inflammation and liver damage. However, STING signaling inhibition with H-151 in vivo or employing STING knockout macrophages significantly reduced these injuries. In-depth mechanism studies have found that the transfer of Nrf2 protein into the nucleus of liver cells after IR in fatty liver is reduced. Pre-treatment with tBHQ ameliorated liver oxidative stress, mitochondrial damage and suppressed the macrophage STING signaling activation.

CONCLUSIONS

Our study reveals a novel mechanism where the interaction between hepatocellular damage and macrophage inflammation intensifies liver IR injury in fatty liver. Enhancing Nrf2 activation to protect mitochondrial from oxidative stress damage and inhibiting macrophage STING signaling activation emerge as promising strategies for clinical intervention in fatty liver IR injury.

Gut microbiota-mediated activation of GSDMD ignites colorectal tumorigenesis

Activation of Gasdermin D (GSDMD) results in its cleavage, oligomerization, and subsequent formation of plasma membrane pores, leading to a form of inflammatory cell death denoted as pyroptosis. The roles of GSDMD in inflammation and immune responses to infection are well documented. However, whether GSDMD also plays a role in sporadic cancer development, especially that in the gut epithelium, remains unknown. Here, we show that GSDMD is activated in colorectal tumors of both human and mouse origins. Ablation of GSDMD in a mouse model of sporadic colorectal cancer resulted in reduced tumor formation in the colon and rectum, suggesting a tumor-promoting role of the protein in the gut. Both antibiotic-mediated depletion of gut microbiota and pharmacological inhibition of NLRP3 inflammasome reduced the activation of GSDMD. Loss of GSDMD resulted in reduced infiltration of immature myeloid cells, and increased numbers of macrophages in colorectal tumors. Activation of GSDMD is also accompanied by the aggregation of the endosomal sorting complex required for transport (ESCRT) membrane repair proteins on the membrane of colorectal tumor cells, suggesting that active membrane repairment may prevent pyroptosis induced by the formation of GSDMD pore in tumor cells. Our results show that gut microbiota/NLRP3-mediated activation of GSDMD promotes the development of colorectal tumors, and supports the use of NLRP3 inhibitors to treat colon cancer.

Role of T cells in liver metastasis

The liver is a major metastatic site (organ) for gastrointestinal cancers (such as colorectal, gastric, and pancreatic cancers) as well as non-gastrointestinal cancers (such as lung, breast, and melanoma cancers). Due to the innate anatomical position of the liver, the apoptosis of T cells in the liver, the unique metabolic regulation of hepatocytes and other potential mechanisms, the liver tends to form an immunosuppressive microenvironment and subsequently form a pre-metastatic niche (PMN), which can promote metastasis and colonization by various tumor cells(TCs). As a result, the critical role of immunoresponse in liver based metastasis has become increasingly appreciated. T cells, a centrally important member of adaptive immune response, play a significant role in liver based metastases and clarifying the different roles of the various T cells subsets is important to guide future clinical treatment. In this review, we first introduce the predisposing factors and related mechanisms of liver metastasis (LM) before introducing the PMN and its transition to LM. Finally, we detail the role of different subsets of T cells in LM and advances in the management of LM in order to identify potential therapeutic targets for patients with LM.

Mechanism study of tyrosine phosphatase shp-1 in inhibiting hepatocellular carcinoma progression by regulating the SHP2/GM-CSF pathway in TAMs

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. Macrophage-mediated innate immune responses play a crucial role in tumor development. This study revealed the mechanism of SHP-1 in regulating HCC progression. SHP-1 inhibits tumour development in vivo. Increasing SHP-1 expression in macrophages promotes the expression of p-SHP-1, SHP2, and p-SHP-2. In macrophages GM-CSF recruits SHP-2 to the GM-CSF receptor GM-CSFR induces p-SHP-2 dephosphorylation. GM-CSF recruits p-SHP-2 for dephosphorylation by up-regulating HoxA10HOXA10 activates the transcription of TGFβ2 by interacting with tandem cis-elements in the promoter thereby regulating the proliferation and migration of liver cancer cells. GM-CSF inhibits SHP-1 regulation of p-SHP-1, SHP2, and p-SHP-2 in macrophages. Detailed studies have shown that SHP-1 regulates SHP2 expression, and SHP-1 and SHP2 are involved in macrophage M2 polarisation. SHP-1 inhibits HOXA10 and TGFβ2 which in turn regulates the expression of the migration-associated proteins, MMP2/9, and the migration of hepatocellular carcinoma cells. Overexpression of SHP-1 inhibits macrophage M2 polarisation via the p-STAT3/6 signalling pathway Classical markers arginase-1, CD206, CD163 and regulate the expression of M2 polarisation cytokines IL-4 and IL-10. In addition, hypoxia-induced ROS inhibited SHP-1 regulation by suppressing the expression of p-SHP-1. The combined effect of GM-CSF and ROS significantly increased p-HOXA10/TGFβ2 and macrophage M2 polarisation, and the regulatory effect of ROS was significantly suppressed by GM-CSF knockdown. These findings suggest that increasing the expression of tyrosine phosphatase SHP-1 can inhibit hepatocellular carcinoma progression by modulating the SHP2/GM-CSF pathway in TAM and thus inhibit the progression of hepatocellular carcinoma.

Comprehensive Analysis of Predictive Value and the potential therapeutic target of NLRP3 inflammasome in glioma based on tumor microenvironment

BACKGROUND

Glioma exhibits high recurrence rates and poor prognosis. The nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome plays a crucial role in inflammation. There is a lack of research exploring the NLRP3 in glioma.

METHODS

We used several databases, networks, Western blotting, multiple immunofluorescence staining to analyze the role of NLRP3 in inflammatory tumor microenvironment (TME).

RESULTS

NLRP3 is higher-expression in glioma with a low mutation load. NLRP3 expression is linked to the infiltration of immune cells, chemokines, immunomodulators, and the TME. Signaling pathways, co-expression genes and interacting proteins contribute to the up-regulation of NLRP3. Patients responding to immunotherapy positively tend to have lower NLRP3 expression relating to the overall survival based on nomogram. Sensitivity to molecular medicines is observed in relation to NLRP3.

CONCLUSION

The NLRP3 inflammasome plays a pivotal role in TME which could serve as a higher predictive value biomarker and therapeutic target for glioma treatment.

ER stress promotes mitochondrial calcium overload and activates the ROS/NLRP3 axis to mediate fatty liver ischemic injury

BACKGROUND

Fatty livers are widely accepted as marginal donors for liver transplantation but are more susceptible to liver ischemia and reperfusion (IR) injury. Increased macrophage-related inflammation plays an important role in the aggravation of fatty liver IR injury. Here, we investigate the precise mechanism by which endoplasmic reticulum (ER) stress activates macrophage NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) signaling by regulating mitochondrial calcium overload in fatty liver IR.

METHODS

Control- and high-fat diet-fed mice were subjected to a partial liver IR model. The ER stress, mitochondrial calcium levels, and NLRP3 signaling pathway in macrophages were analyzed.

RESULTS

Liver steatosis exacerbated liver inflammation and IR injury and enhanced NLRP3 activation in macrophages. Myeloid NLRP3 deficiency attenuated intrahepatic inflammation and fatty liver injury following IR. Mechanistically, increased ER stress and mitochondrial calcium overload were observed in macrophages obtained from mouse fatty livers after IR. Suppression of ER stress by tauroursodeoxycholic acid effectively downregulated mitochondrial calcium accumulation and suppressed NLRP3 activation in macrophages, leading to decreased inflammatory IR injury in fatty livers. Moreover, Xestospongin-C-mediated inhibition of mitochondrial calcium influx decreased reactive oxygen species (ROS) expression in macrophages after IR. Scavenging of mitochondrial ROS by mito-TEMPO suppressed macrophage NLRP3 activation and IR injury in fatty livers, indicating that excessive mitochondrial ROS production was responsible for macrophage NLRP3 activation induced by mitochondrial calcium overload. Patients with fatty liver also exhibited upregulated activation of NLRP3 and the ER stress signaling pathway after IR.

CONCLUSIONS

Our findings suggest that ER stress promotes mitochondrial calcium overload to activate ROS/NLRP3 signaling pathways within macrophages during IR-stimulated inflammatory responses associated with fatty livers.

Tumor associated macrophages as key contributors and targets in current and future therapies for melanoma

INTRODUCTION

Despite the success of immunotherapies for melanoma in recent years, there remains a significant proportion of patients who do not yet derive benefit from available treatments. Immunotherapies currently licensed for clinical use target the adaptive immune system, focussing on Tcell interactions and functions. However, the most prevalent immune cells within the tumor microenvironment (TME) of melanoma are macrophages, a diverse immune cell subset displaying high plasticity, to which no current therapies are yet directly targeted. Macrophages have been shown not only to activate the adaptive immune response, and enhance cancer cell killing, but, when influenced by factors within the TME of melanoma, these cells also promote melanoma tumorigenesis and metastasis.

AREAS COVERED

We present a review of the most up-to-date literatureavailable on PubMed, focussing on studies from within the last 10 years. We also include data from ongoing and recent clinical trials targeting macrophages in melanoma listed on clinicaltrials.gov.

EXPERT OPINION

Understanding the multifaceted role of macrophages in melanoma, including their interactions with immune and cancer cells, the influence of current therapies on macrophage phenotype and functions and how macrophages could be targeted with novel treatment approaches, are all critical for improving outcomes for patients with melanoma.

cGAS-STING, inflammasomes and pyroptosis: an overview of crosstalk mechanism of activation and regulation

BACKGROUND

Intracellular DNA-sensing pathway cGAS-STING, inflammasomes and pyroptosis act as critical natural immune signaling axes for microbial infection, chronic inflammation, cancer progression and organ degeneration, but the mechanism and regulation of the crosstalk network remain unclear. Cellular stress disrupts mitochondrial homeostasis, facilitates the opening of mitochondrial permeability transition pore and the leakage of mitochondrial DNA to cell membrane, triggers inflammatory responses by activating cGAS-STING signaling, and subsequently induces inflammasomes activation and the onset of pyroptosis. Meanwhile, the inflammasome-associated protein caspase-1, Gasdermin D, the CARD domain of ASC and the potassium channel are involved in regulating cGAS-STING pathway. Importantly, this crosstalk network has a cascade amplification effect that exacerbates the immuno-inflammatory response, worsening the pathological process of inflammatory and autoimmune diseases. Given the importance of this crosstalk network of cGAS-STING, inflammasomes and pyroptosis in the regulation of innate immunity, it is emerging as a new avenue to explore the mechanisms of multiple disease pathogenesis. Therefore, efforts to define strategies to selectively modulate cGAS-STING, inflammasomes and pyroptosis in different disease settings have been or are ongoing. In this review, we will describe how this mechanistic understanding is driving possible therapeutics targeting this crosstalk network, focusing on the interacting or regulatory proteins, pathways, and a regulatory mitochondrial hub between cGAS-STING, inflammasomes, and pyroptosis.

SHORT CONCLUSION

This review aims to provide insight into the critical roles and regulatory mechanisms of the crosstalk network of cGAS-STING, inflammasomes and pyroptosis, and to highlight some promising directions for future research and intervention.

Mechanisms and effects of NLRP3 in digestive cancers

Inflammasomes are thought to be important mediators of host defense against microbial pathogens and maintenance of gastrointestinal tract homeostasis. They can modulate caspase-1 to promote IL-18 and IL-1β secretion and promote phagocytosis induced by bacterial pathogens. NLRP3 is an inflammasome comprising a multiprotein complex assembled by pattern recognition receptors in the cell cytoplasm. It is a crucial component of the innate immune system. Dysregulation of NLRP3 may contribute to inflammatory diseases and intestinal cancers. Recent research suggests that NLRP3 plays an essential role in tumor development; therefore, intensive study of its mechanism is warranted as it could play a key role in the treatment of digestive system tumors. In this review, we discuss the mechanism and role of NLRP3 in tumors of the digestive system and response strategies to modulate NLRP3 for potential use in tumor treatment.

Emerging mechanisms and implications of cGAS-STING signaling in cancer immunotherapy strategies

The intricate interplay between the human immune system and cancer development underscores the central role of immunotherapy in cancer treatment. Within this landscape, the innate immune system, a critical sentinel protecting against tumor incursion, is a key player. The cyclic GMP-AMP synthase (cGAS) and stimulator of interferon genes (STING) pathway has been found to be a linchpin of innate immunity: activation of this signaling pathway orchestrates the production of type I interferon (IFN-α/β), thus fostering the maturation, differentiation, and mobilization of immune effectors in the tumor microenvironment. Furthermore, STING activation facilitates the release and presentation of tumor antigens, and therefore is an attractive target for cancer immunotherapy. Current strategies to activate the STING pathway, including use of pharmacological agonists, have made substantial advancements, particularly when combined with immune checkpoint inhibitors. These approaches have shown promise in preclinical and clinical settings, by enhancing patient survival rates. This review describes the evolving understanding of the cGAS-STING pathway's involvement in tumor biology and therapy. Moreover, this review explores classical and non-classical STING agonists, providing insights into their mechanisms of action and potential for optimizing immunotherapy strategies. Despite challenges and complexities, the cGAS-STING pathway, a promising avenue for enhancing cancer treatment efficacy, has the potential to revolutionize patient outcomes.

Role of cGAS-STING in colorectal cancer: A new window for treatment strategies

Colorectal cancer (CRC) is a common and deadly form of cancer, leading to the need for new therapeutic targets and strategies for treatment. Recent studies have shown the cGAS-STING pathway to be a promising target for cancer therapy. The cGAS-STING pathway is a part of the innate immune system and serves to identify DNA damage and viral infection, promoting an immune response. Activation of this pathway leads to the production of immune mediators, such as type I interferons, that activate immune cells to attack cancer cells. Research has identified the cGAS-STING pathway as a frequently dysregulated component in CRC, promoting tumor growth and metastasis, or leading to chronic inflammation and tissue damage. The modulation of this pathway presents a potential therapeutic approach, either activating or inhibiting the pathway to enhance the immune response and prevent inflammation, respectively. Developing drugs that can modulate the cGAS-STING pathway offers promise for improving treatment outcomes for CRC patients. The present review explores recent research on the role of cGAS-STING in CRC and highlights the potential therapeutic benefits of targeting this pathway.

Harnessing the innate immune system by revolutionizing macrophage-mediated cancer immunotherapy

Immunotherapy is a promising and safer alternative to conventional cancer therapies. It involves adaptive T-cell therapy, cancer vaccines, monoclonal antibodies, immune checkpoint blockade (ICB), and chimeric antigen receptor (CAR) based therapies. However, most of these modalities encounter restrictions in solid tumours owing to a dense, highly hypoxic and immune-suppressive microenvironment as well as the heterogeneity of tumour antigens. The elevated intra-tumoural pressure and mutational rates within fastgrowing solid tumours present challenges in efficient drug targeting and delivery. The tumour microenvironment is a dynamic niche infiltrated by a variety of immune cells, most of which are macrophages. Since they form a part of the innate immune system, targeting macrophages has become a plausible immunotherapeutic approach. In this review, we discuss several versatile approaches (both at pre-clinical and clinical stages) such as the direct killing of tumour-associated macrophages, reprogramming pro-tumour macrophages to anti-tumour phenotypes, inhibition of macrophage recruitment into the tumour microenvironment, novel CAR macrophages, and genetically engineered macrophages that have been devised thus far. These strategies comprise a strong and adaptable macrophage-toolkit in the ongoing fight against cancer and by understanding their significance, we may unlock the full potential of these immune cells in cancer therapy.

Innate Immune Cells in the Tumor Microenvironment of Liver Metastasis from Colorectal Cancer: Contribution to a Comprehensive Therapy

Colorectal cancer (CRC) is the third most prevalent type of cancer, and liver metastasis is the most common site of metastatic development. In the tumor microenvironment (TME), various innate immune cells are known to influence cancer progression and metastasis occurrence. CD274 (PD-L1) and CD206 (MRC1) are proteins that have been associated with poor prognosis and disease progression. We conducted a study on tumoral and non-tumoral biopsies from 47 patients with CRC liver metastasis, using flow cytometry to phenotypically characterize innate immune cells. Our findings showed an increase in the expression of CD274 on classical, intermediate, and non-classical monocytes when comparing tumor with non-tumor samples. Furthermore, tumor samples with a desmoplastic growth pattern exhibited a significantly decreased percentage of CD274- and CD206-positive cells in all monocyte populations compared to non-desmoplastic samples. We found a correlation between a lower expression of CD206 or CD274 on classical, intermediate, and non-classical monocytes and increased disease-free survival, which points to a better prognosis for these patients. In conclusion, our study has identified potential new targets and biomarkers that could be incorporated into a personalized medicine approach to enhance the outcome for colorectal cancer patients.