Human NLRC4 promotes cancer survival and is associated to type-I interferon signaling and immune infiltration.

The immune system can control cancer progression. However, even though some innate immune sensors of cellular stress are expressed intrinsically in epithelial cells, their potential role in cancer aggressiveness and subsequent overall survival in humans is mainly unknown. Here, we show that NLR family CARD Domain Containing 4 (NLRC4) is downregulated in epithelial tumor cells of colorectal cancer (CRC) patients by using spatial tissue imaging. Strikingly, only the loss of tumor NLRC4 but not stromal is associated with poor immune infiltration (mainly dendritic and CD4+/CD8+ T cells) and accurately predicts progression to metastatic Stage IV and decrease of overall survival. By combining multi-omics approaches, we show that restoring NLRC4 expression in human colorectal cancer cells triggers a broad inflammasome-independent immune reprogramming consisting of Type-I IFN signaling genes and the release of chemokines and myeloid growth factors involved in the tumor infiltration and activation of dendritic cells (DCs) and T cells. Consistently, such reprogramming in cancer cells is sufficient to directly mature human DCs towards a Th1 antitumor immune response through IL-12 production in vitro. In multiple human carcinomas (colorectal, lung, and skin), we confirmed that NLRC4 expression in patient tumors is strongly associated with Type-I IFN genes, immune infiltrates and high microsatellite instability. Thus, we shed light on the epithelial innate immune sensor NLRC4 as a novel therapeutic target to promote an efficient antitumor immune response against the aggressiveness of various carcinomas.

THBS1+ myeloid cells expand in SLD hepatocellular carcinoma and contribute to immunosuppression and unfavorable prognosis through TREM1.

Hepatocellular carcinoma (HCC) is an inflammation-associated cancer arising from viral or non-viral etiologies including steatotic liver diseases (SLDs). Expansion of immunosuppressive myeloid cells is a hallmark of inflammation and cancer, but their heterogeneity in HCC is not fully resolved and might underlie immunotherapy resistance. Here, we present a high-resolution atlas of innate immune cells from patients with HCC that unravels an SLD-associated contexture characterized by influx of inflammatory and immunosuppressive myeloid cells, including a discrete population of THBS1+ regulatory myeloid (Mreg) cells expressing monocyte- and neutrophil-affiliated genes. THBS1+ Mreg cells expand in SLD-associated HCC, populate fibrotic lesions, and are associated with poor prognosis. THBS1+ Mreg cells are CD163+ but distinguished from macrophages by high expression of triggering receptor expressed on myeloid cells 1 (TREM1), which contributes to their immunosuppressive activity and promotes HCC tumor growth in vivo. Our data support myeloid subset-targeted immunotherapies to treat HCC.

Native low-density lipoproteins are priming signals of the NLRP3 inflammasome/interleukin-1ß pathway in human adipose tissue and macrophages.

Elevated plasma numbers of atherogenic apoB-lipoproteins (apoB), mostly as low-density lipoproteins (LDL), predict diabetes risk by unclear mechanisms. Upregulation of the NLRP3 inflammasome/interleukin-1 beta (IL-1ß) system in white adipose tissue (WAT) is implicated in type 2 diabetes (T2D); however, metabolic signals that stimulate it remain unexplored. We hypothesized that (1) subjects with high-apoB have higher WAT IL-1ß-secretion than subjects with low-apoB, (2) WAT IL-1ß-secretion is associated with T2D risk factors, and (3) LDL prime and/or activate the WAT NLRP3 inflammasome. Forty non-diabetic subjects were assessed for T2D risk factors related to systemic and WAT glucose and fat metabolism. Regulation of the NLRP3 inflammasome was explored using LDL without/with the inflammasome's priming and activation controls (LPS and ATP). LDL induced IL1B-expression and IL-1ß-secretion in the presence of ATP in WAT and macrophages. Subjects with high-apoB had higher WAT IL-1ß-secretion independently of covariates. The direction of association of LDL-induced WAT IL-1ß-secretion to T2D risk factors was consistently pathological in high-apoB subjects only. Adjustment for IL-1ß-secretion eliminated the association of plasma apoB with T2D risk factors. In conclusion, subjects with high-apoB have higher WAT IL-1ß-secretion that may explain their risk for T2D and may be related to LDL-induced priming of the NLRP3 inflammasome.ClinicalTrials.gov (NCT04496154): Omega-3 to Reduce Diabetes Risk in Subjects With High Number of Particles That Carry "Bad Cholesterol" in the Blood-Full Text View-ClinicalTrials.gov.

Inflammasomes in Cancer Progression and Anti-Tumor Immunity.

The inflammasomes are critical regulators of innate immunity, inflammation and cell death and have emerged as important regulators of cancer development and control. Inflammasomes are assembled by pattern recognition receptors (PRR) following the sensing of microbial- or danger-associated molecular patterns (MAMPs/DAMPs) and elicit inflammation through the oligomerization and activation of inflammatory caspases. These cysteinyl-aspartate proteases cleave the proinflammatory cytokines IL-1ß and IL-18 into their biologically active mature form. The roles of the inflammasomes and associated pro-inflammatory cytokines vary greatly depending on the cancer type. Here we discuss recent studies highlighting contrasting roles of the inflammasome pathway in curbing versus promoting tumorigenesis. On one hand, the inflammasomes participate in stimulating anti-tumor immunity, but they have also been shown to contribute to immunosuppression or to directly promote tumor cell survival, proliferation, and metastasis. A better understanding of inflammasome functions in different cancers is thus critical for the design of novel cancer immunotherapies.

The Metabolic Control of Myeloid Cells in the Tumor Microenvironment.

Myeloid cells are a key determinant of tumor progression and patient outcomes in a range of cancers and are therefore being actively pursued as targets of new immunotherapies. The recent use of high-dimensional single-cell approaches, e.g., mass cytometry and single-cell RNA-sequencing (scRNA-seq) has reinforced the predominance of myeloid cells in the tumor microenvironment and uncovered their phenotypic diversity in different cancers. The cancerous metabolic environment has emerged as a critical modulator of myeloid cell functions in anti-tumor immunity versus immune suppression and immune evasion. Here, we discuss mechanisms of immune-metabolic crosstalk in tumorigenesis, with a particular focus on the tumor-associated myeloid cell's metabolic programs. We highlight the impact of several metabolic pathways on the pro-tumoral functions of tumor-associated macrophages and myeloid-derived suppressor cells and discuss the potential myeloid cell metabolic checkpoints for cancer immunotherapy, either as monotherapies or in combination with other immunotherapies.

Host-Microbiota Interactions in Liver Inflammation and Cancer.

Hepatocellular carcinoma (HCC) is a classical inflammation-promoted cancer that occurs in a setting of liver diseases, including nonalcoholic fatty liver disease (NAFLD) or alcoholic liver disease (ALD). These pathologies share key characteristics, notably intestinal dysbiosis, increased intestinal permeability and an imbalance in bile acids, choline, fatty acids and ethanol metabolites. Translocation of microbial- and danger-associated molecular patterns (MAMPs and DAMPs) from the gut to the liver elicits profound chronic inflammation, leading to severe hepatic injury and eventually HCC progression. In this review, we first describe how the gut and the liver communicate and discuss mechanisms by which the intestinal microbiota elicit hepatic inflammation and HCC. We focus on the role of microbial products, e.g., MAMPs, host inflammatory effectors and host-microbiome-derived metabolites in tumor-promoting mechanisms, including cell death and senescence. Last, we explore the potential of harnessing the microbiota to treat liver diseases and HCC.

The IL-1 Receptor Is Required to Maintain Neutrophil Viability and Function During Aspergillus fumigatus Airway Infection.

Aspergillus fumigatus airway infections are associated with increased rates of hospitalizations and declining lung function in patients with chronic lung disease. While the pathogenesis of invasive A. fumigatus infections is well studied, little is known about the development and progression of airway infections. Previous studies have demonstrated a critical role for the IL-1 cytokines, IL-1α and IL-1ß in enhancing pulmonary neutrophil recruitment during invasive aspergillosis. Here we use a mouse model of A. fumigatus airway infection to study the role of these IL-1 cytokines in immunocompetent mice. In the absence of IL-1 receptor signaling, mice exhibited reduced numbers of viable pulmonary neutrophils and increased levels of neutrophil apoptosis during fungal airway infection. Impaired neutrophil viability in these mice was associated with reduced pulmonary and systemic levels of G-CSF, and treatment with G-CSF restored both neutrophil viability and resistance to A. fumigatus airway infection. Taken together, these data demonstrate that IL-1 dependent G-CSF production plays a key role for host resistance to A. fumigatus airway infection through suppressing neutrophil apoptosis at the site of infection.

Estrogen-related receptor alpha (ERRα) is a key regulator of intestinal homeostasis and protects against colitis.

The estrogen-related receptor alpha (ERRα) is a primary regulator of mitochondrial energy metabolism, function and dynamics, and has been implicated in autophagy and immune regulation. ERRα is abundantly expressed in the intestine and in cells of the immune system. However, its role in inflammatory bowel disease (IBD) remains unknown. Here, we report a protective role of ERRα in the intestine. We found that mice deficient in ERRα were susceptible to experimental colitis, exhibiting increased colon inflammation and tissue damage. This phenotype was mediated by impaired compensatory proliferation of intestinal epithelial cells (IEC) following injury, enhanced IEC apoptosis and necrosis and reduced mucus-producing goblet cell counts. Longitudinal analysis of the microbiota demonstrated that loss of ERRα lead to a reduction in microbiome α-diversity and depletion of healthy gut bacterial constituents. Mechanistically, ERRα mediated its protective effects by acting within the radio-resistant compartment of the intestine. It promoted disease tolerance through transcriptional control of key genes involved in intestinal tissue homeostasis and repair. These findings provide new insights on the role of ERRα in the gut and extends our current knowledge of nuclear receptors implicated in IBD.

Hepatocellular Carcinoma Immune Landscape and the Potential of Immunotherapies.

Hepatocellular carcinoma (HCC) is the most common liver tumor and among the deadliest cancers worldwide. Advanced HCC overall survival is meager and has not improved over the last decade despite approval of several tyrosine kinase inhibitors (TKi) for first and second-line treatments. The recent approval of immune checkpoint inhibitors (ICI) has revolutionized HCC palliative care. Unfortunately, the majority of HCC patients fail to respond to these therapies. Here, we elaborate on the immune landscapes of the normal and cirrhotic livers and of the unique HCC tumor microenvironment. We describe the molecular and immunological classifications of HCC, discuss the role of specific immune cell subsets in this cancer, with a focus on myeloid cells and pathways in anti-tumor immunity, tumor promotion and immune evasion. We also describe the challenges and opportunities of immunotherapies in HCC and discuss new avenues based on harnessing the anti-tumor activity of myeloid, NK and γδ T cells, vaccines, chimeric antigen receptors (CAR)-T or -NK cells, oncolytic viruses, and combination therapies.

Glioblastoma Immune Landscape and the Potential of New Immunotherapies.

Glioblastoma (GBM) are the most common tumors of the central nervous system and among the deadliest cancers in adults. GBM overall survival has not improved over the last decade despite optimization of therapeutic standard-of-care. While immune checkpoint inhibitors (ICI) have revolutionized cancer care, they unfortunately have little therapeutic success in GBM. Here, we elaborate on normal brain and GBM-associated immune landscapes. We describe the role of microglia and tumor-associated macrophages (TAMs) in immune suppression and highlight the impact of energy metabolism in immune evasion. We also describe the challenges and opportunities of immunotherapies in GBM and discuss new avenues based on harnessing the anti-tumor activity of myeloid cells, vaccines, chimeric antigen receptors (CAR)-T and -NK cells, oncolytic viruses, nanocarriers, and combination therapies.

Migration-induced cell shattering due to DOCK8 deficiency causes a type 2-biased helper T cell response.

Mutations that impact immune cell migration and result in immune deficiency illustrate the importance of cell movement in host defense. In humans, loss-of-function mutations in DOCK8, a guanine exchange factor involved in hematopoietic cell migration, lead to immunodeficiency and, paradoxically, allergic disease. Here, we demonstrate that, like humans, Dock8-/- mice have a profound type 2 CD4+ helper T (TH2) cell bias upon pulmonary infection with Cryptococcus neoformans and other non-TH2 stimuli. We found that recruited Dock8-/-CX3CR1+ mononuclear phagocytes are exquisitely sensitive to migration-induced cell shattering, releasing interleukin (IL)-1ß that drives granulocyte-macrophage colony-stimulating factor (GM-CSF) production by CD4+ T cells. Blocking IL-1ß, GM-CSF or caspase activation eliminated the type-2 skew in mice lacking Dock8. Notably, treatment of infected wild-type mice with apoptotic cells significantly increased GM-CSF production and TH2 cell differentiation. This reveals an important role for cell death in driving type 2 signals during infection, which may have implications for understanding the etiology of type 2 CD4+ T cell responses in allergic disease.

The plot thickens: OTULIN regulation in cell death.

We recently demonstrated that post-translational modifications of the OTU deubiquitinase with linear linkage specificity (OTULIN) regulate its function in cell death. OTULIN hyper-phosphorylation promotes necroptosis by locking ring finger protein 31 (RNF31, also known as HOIP) away from the cylindromatosis (CYLD) complex, resulting in altered receptor interacting serine/threonine kinase 1 (RIPK1) ubiquitination. Further, we identified dual specificity phosphatase 14 (DUSP14) as an OTULIN phosphatase that limits necroptosis.

Immunometabolism of Macrophages in Bacterial Infections.

Macrophages are important effectors of tissue homeostasis, inflammation and host defense. They are equipped with an arsenal of pattern recognition receptors (PRRs) necessary to sense microbial- or danger-associated molecular patterns (MAMPs/DAMPs) and elicit rapid energetically costly innate immunity responses to protect the organism. The interaction between cellular metabolism and macrophage innate immunity is however not limited to answering the cell's energy demands. Mounting evidence now indicate that in response to bacterial sensing, macrophages undergo metabolic adaptations that contribute to the induction of innate immunity signaling and/or macrophage polarization. In particular, intermediates of the glycolysis pathway, the Tricarboxylic Acid (TCA) cycle, mitochondrial respiration, amino acid and lipid metabolism directly interact with and modulate macrophage effectors at the epigenetic, transcriptional and post-translational levels. Interestingly, some intracellular bacterial pathogens usurp macrophage metabolic pathways to attenuate anti-bacterial defenses. In this review, we highlight recent evidence describing such host-bacterial immunometabolic interactions.

The mitochondrial protease HtrA2 restricts the NLRP3 and AIM2 inflammasomes.

Activation of the inflammasome pathway is crucial for effective intracellular host defense. The mitochondrial network plays an important role in inflammasome regulation but the mechanisms linking mitochondrial homeostasis to attenuation of inflammasome activation are not fully understood. Here, we report that the Parkinson's disease-associated mitochondrial serine protease HtrA2 restricts the activation of ASC-dependent NLRP3 and AIM2 inflammasomes, in a protease activity-dependent manner. Consistently, disruption of the protease activity of HtrA2 results in exacerbated NLRP3 and AIM2 inflammasome responses in macrophages ex vivo and systemically in vivo. Mechanistically, we show that the HtrA2 protease activity regulates autophagy and controls the magnitude and duration of inflammasome signaling by preventing prolonged accumulation of the inflammasome adaptor ASC. Our findings identify HtrA2 as a non-redundant mitochondrial quality control effector that keeps NLRP3 and AIM2 inflammasomes in check.

The Interleukin (IL)-1R1 pathway is a critical negative regulator of PyMT-mediated mammary tumorigenesis and pulmonary metastasis.

Breast cancer is the most common cancer in women and the second leading cause of female cancer-related deaths worldwide. Inflammation is an established hallmark of tumorigenesis and an important determinant of tumor outcome and response to therapy. With advances in cancer immunotherapy, there is an urgent need to dissect the contribution of specific immune effectors in cancer development. Here, we genetically investigated the role of the Interleukin-1 (IL-1) receptor 1 (IL-1R1) pathway in breast cancer tumorigenesis and metastasis using the MMTV-PyMT mouse model. Our results indicate that IL-1R1 signaling suppresses mammary tumor cell proliferation early in tumorigenesis and curbs breast cancer outgrowth and pulmonary metastasis. We show that PyMT/Il1r1-/- mice had a higher primary tumor burden and increased mortality rate compared with IL-1R1-sufficient PyMT control mice. This phenotype was independent of the inflammatory caspases-1/-11 but driven by IL-1α, as PyMT/Il1a-/- mice phenocopied PyMT/Il1r1-/- mice. Collectively, our results suggest that IL-1α-mediated IL-1R1 signaling is tumor-suppressive in PyMT-driven breast cancer.

Linking cancer-induced Nlrp3 inflammasome activation to efficient NK cell-mediated immunosurveillance.

We have recently demonstrated that the Nlrp3 inflammasome can detect the presence of colorectal cancer (CRC) metastatic growth in the liver and limit its growth. Inflammasome signaling primed natural killer (NK) cells through Interleukin (IL)-18 and activated their ability to trigger FasL-induced apoptosis of the tumor.

Carcinoembryonic Antigen Cell Adhesion Molecule 1 long isoform modulates malignancy of poorly differentiated colon cancer cells.

OBJECTIVE: Nearly 20%-29% of patients with colorectal cancer (CRC) succumb to liver or lung metastasis and there is a dire need for novel targets to improve the survival of patients with metastasis. The long isoform of the Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1-L or CC1-L) is a key regulator of immune surveillance in primary CRC, but its role in metastasis remains largely unexplored. We have examined how CC1-L expression impacts on colon cancer liver metastasis. DESIGN: Murine MC38 transfected with CC1-L were evaluated in vitro for proliferation, migration and invasion, and for in vivo experimental liver metastasis. Using shRNA silencing or pharmacological inhibition, we delineated the role in liver metastasis of Chemokine (C-C motif) Ligand 2 (CCL2) and Signal Transducer and Activator of Transcription 3 (STAT3) downstream of CC1-L. We further assessed the clinical relevance of these findings in a cohort of patients with CRC. RESULTS: MC38-CC1-L-expressing cells exhibited significantly reduced in vivo liver metastasis and displayed decreased CCL2 chemokine secretion and reduced STAT3 activity. Down-modulation of CCL2 expression and pharmacological inhibition of STAT3 activity in MC38 cells led to reduced cell invasion capacity and decreased liver metastasis. The clinical relevance of our findings is illustrated by the fact that high CC1 expression in patients with CRC combined with some inflammation-regulated and STAT3-regulated genes correlate with improved 10-year survival. CONCLUSIONS: CC1-L regulates inflammation and STAT3 signalling and contributes to the maintenance of a less-invasive CRC metastatic phenotype of poorly differentiated carcinomas.

The Nlrp3 Inflammasome Suppresses Colorectal Cancer Metastatic Growth in the Liver by Promoting Natural Killer Cell Tumoricidal Activity.

The crosstalk between inflammation and tumorigenesis is now clearly established. However, how inflammation is elicited in the metastatic environment and the corresponding contribution of innate immunity pathways in suppressing tumor growth at secondary sites are poorly understood. Here, we show that mice deficient in Nlrp3 inflammasome components had exacerbated liver colorectal cancer metastatic growth, which was mediated by impaired interleukin-18 (IL-18) signaling. Control of tumor growth was independent of differential cancer cell colonization or proliferation, intestinal microbiota effects, or tumoricidal activity by the adaptive immune system. Instead, the inflammasome-IL-18 pathway impacted maturation of hepatic NK cells, surface expression of the death ligand FasL, and capacity to kill FasL-sensitive tumors. Our results define a regulatory signaling circuit within the innate immune system linking inflammasome activation to effective NK-cell-mediated tumor attack required to suppress colorectal cancer growth in the liver.

The Inflammatory Caspases-1 and -11 Mediate the Pathogenesis of Dermatitis in Sharpin-Deficient Mice.

Chronic proliferative dermatitis in mice (cpdm) is a spontaneous multiorgan inflammatory disorder with pathological hallmarks similar to atopic dermatitis and psoriasis in humans. Cpdm mice lack expression of SHANK-associated RH domain-interacting protein, an adaptor of the linear ubiquitin assembly complex, which acts in the NF-κB pathway to promote inflammation and protect from apoptosis and necroptosis. Although skin inflammation in cpdm mice is driven by TNF- and RIPK1-induced cell death, the contribution of initiating innate immunity sensors and additional inflammatory pathways remains poorly characterized. In this article, we show that inflammasome signaling, including the expression and activation of the inflammatory caspase-1 and -11 and IL-1 family cytokines, was highly upregulated in the skin of cpdm mice prior to overt disease onset. Genetic ablation of caspase-1 and -11 from cpdm mice significantly reduced skin inflammation and delayed disease onset, whereas systemic immunological disease persisted. Loss of Nlrp3 also attenuated skin disease, albeit more variably. Strikingly, induction of apoptosis and necroptosis effectors was sharply decreased in the absence of caspase-1 and -11. These results position the inflammasome as an important initiating signal in skin disease pathogenesis and provide novel insights about inflammasome and cell death effector cross-talk in the context of inflammatory diseases.

Role of programmed necrosis and cell death in intestinal inflammation.

PURPOSE OF REVIEW: To critically review recent advances on the role of programmed necrosis and other cell death modalities in intestinal health and inflammatory bowel disease. RECENT FINDINGS: Tight regulation of intestinal epithelial cell proliferation and cell death is required for intestinal physiology, and to maintain an integral barrier that restricts microbiota translocation and ensures immune tolerance. Apoptosis has long been considered as a normal part of intestinal epithelial cell turnover. However, recent studies have demonstrated that excessive cell death leads to deleterious intestinal inflammation, as is observed in inflammatory bowel disease. Additionally, a novel form of cell death dubbed programmed necrosis, or necroptosis, has been recently shown to be pathological in the gut. SUMMARY: The role of cell death in the intestine is complex and its potential implication in intestinal diseases, and inflammatory bowel disease in particular, needs to be reevaluated.