NLRC5, the largest member of the nucleotide-binding and oligomerization domain (NOD)-like receptor (NLR) family, has been reported to participate in the regulation of immune function and is associated with chronic inflammatory diseases. However, the biological function of NLRC5 in hepatocellular carcinoma (HCC) has not been fully demonstrated. The aim of this study is to evaluate NLRC5 expression in the tumor tissues of HCC patients undergoing surgical treatment, assess its prognostic value, and explore its relationship with critical immune-related molecules within the tumor microenvironment. A total of 100 patients with hepatitis B virus-associated HCC receiving surgical treatment were enrolled in the study. Immunohistochemical results were obtained by scoring the intensity of cellular staining and the percentage of positive cells in the tissue sections. The association between NLRC5 expression levels and the main clinicopathological factors was analyzed by Chi-square test method. The prognostic values were analyzed by COX regression model and the Kaplan-Meier survival curve. Receiver operating characteristic (ROC) curve analysis was performed to assess the predictive performance of NLRC5 in postoperative patients with HCC. IHC showed that high expression of NLRC5 was observed in 67% of HCC tissue samples. Chi-square test showed that NLRC5 was a risk factor associated with tumor number, satellite nodule, and envelope invasion. Kaplan-Meier survival curves and COX survival analysis showed that high expression of NLRC5 was significantly associated with decreased overall survival (OS) in HCC patients (HR = 1.79, 95% CI 1.03-3.12, p = .041). However, univariate logistic regression analysis revealed that NLRC5 showed positive relationship with GZMB and CD8α suggesting its role in immune escape of HCC. ROC curve analysis showed that the combination of tumor number, envelope invasion, and NLRC5 expression (area under the curve = 0.824, sensitivity = 77.30%, specificity = 82.4%) can more accurately evaluate the prognosis of HCC patients compared to the combination of only tumor number and envelope invasion (area under the curve = 0.690, sensitivity = 43.9%, specificity = 94.1%).NLRC5 plays a crucial role in progression of HCC and can be considered as a potential prognostic and predictive biomarker. Targeting NLRC5 may provide an attractive therapeutic approach for HCC.

BACKGROUND: This study aimed to explore the molecular mechanism through which circular RNA of ataxin 7 (circATXN7) regulates the proliferation and invasion of esophageal cancer (EC) cells via microRNA (miR)-4319/NLR family CARD domain containing 5 (NLRC5).
METHODS: The localization of circATXN7 in EC cells was determined by RNA fluorescent in situ hybridization (RNA-FISH). The mRNA levels of circATXN7, miR-4319, and NLRC5 were quantified by reverse transcription-polymerase chain reactions. The binding activity of circATXN7 to miR-4319 was assessed using RNA-binding protein immunoprecipitation. Whether circATXN7 regulates the proliferation of EC cells via miR-4319 was explored using dual-luciferase reporter gene colony formation assays. Protein levels were quantified by western blot. The effect of NLRC5 on the proliferation and invasion of EC cells was examined using colony formation and Transwell assays. A subcutaneous transplanted tumor nude mouse model was established to observe the effect of circATXN7 on the proliferation of EC cells in vivo.
RESULTS: circATXN7 localized mainly to the cytoplasm. Overexpression or inhibition of miR-4319 significantly regulated the proliferation of EC cells, while circATXN7 competitively inhibited miR-4319 expression. Overexpression of miR-4319 significantly inhibited NLRC5 expression, indicating NLRC5 is a downstream regulatory target of miR-4319. circATXN7 influenced NLRC5 expression via miR-4319. In vivo tumor formation experiments in nude mice revealed that knocking down circATXN7 regulated NLRC5 expression via miR-4319 and significantly inhibited the proliferation of EC cells.
CONCLUSIONS: In vitro cell and in vivo animal experiments showed that circATXN7 regulates the proliferation, invasion, and migration of EC cells through the miR-4319/NLRC5 signaling pathway.

BACKGROUND: Temporomandibular joint osteoarthritis (TMJOA) is a degenerative cartilage disease. 17β-estradiol (E2) aggravates the pathological process of TMJOA; however, the mechanisms of its action have not been elucidated. Thus, we investigate the influence of E2 on the cellular biological behaviors of synoviocytes and the molecular mechanisms.
METHODS: Primary fibroblast-like synoviocytes (FLSs) isolated from rats were treated with TNF-α to establish cell model, and phenotypes were evaluated using cell counting kit-8, EdU, Tanswell, enzyme-linked immunosorbent assay, and quantitative real-time PCR (qPCR). The underlying mechanism of E2, FTO-mediated NLRC5 m6A methylation, was assessed using microarray, methylated RNA immunoprecipitation, qPCR, and western blot. Moreover, TMJOA-like rat model was established by intra-articular injection of monosodium iodoacetate (MIA), and bone morphology and pathology were assessed using micro-CT and H&E staining.
RESULTS: The results illustrated that E2 facilitated the proliferation, migration, invasion, and inflammation of TNF-α-treated FLSs. FTO expression was downregulated in TMJOA and was reduced by E2 in FLSs. Knockdown of FTO promoted m6A methylation of NLRC5 and enhanced NLRC5 stability by IGF2BP1 recognition. Moreover, E2 promoted TMJ pathology and condyle remodeling, and increased bone mineral density and trabecular bone volume fraction, which was rescued by NLRC5 knockdown.
CONCLUSIONS: E2 promoted the progression of TMJOA.

Cervical cancer (CC) is the fourth most common cancer among women worldwide. NLR Family CARD Domain Containing 5 (NLRC5) plays an important role in tumorigenesis. However, its effect and mechanism in CC remains unclear. In this study, we aimed to investigate the function of NLRC5 in CC. NLRC5 was found to be down-regulated in CC tissues compared with normal cervical tissues. However, patients with higher NLRC5 expression had better prognosis, patients with higher age, HPV infection, lymph node metastasis, recurrence and histological grade had worse prognosis. Univariate and multivariate analyses showed NLRC5 to be a potential prognostic indicator for CC. Pearson correlation analysis showed that NLRC5 might exert its function in CC through autophagy related proteins, especially LC3. In vitro experiments demonstrated that NLRC5 inhibited LC3 levels and promoted the proliferation, migration, and invasion of CC cells by activating the PI3K/AKT signaling pathway. Treatment with LY294002 reversed the above phenotype. Taken together, our finding suggested that NLRC5 would participate in cervical tumorigenesis and progression by regulating PI3K/AKT signaling pathway. In addition, NLRC5 and LC3 combined as possible predictors in CC.

The incidence and mortality rate of myocardial infarction are increasing per year in China. The polarization of macrophages towards the classically activated macrophages (M1) phenotype is of utmost importance in the progression of inflammatory stress subsequent to myocardial infarction. Poly (ADP-ribose) polymerase 1(PARP1) is the ubiquitous and best characterized member of the PARP family, which has been reported to support macrophage polarization towards the pro-inflammatory phenotype. Yet, the role of PARP1 in myocardial ischemic injury remains to be elucidated. Here, we demonstrated that a myocardial infarction mouse model induced cardiac damage characterized by cardiac dysfunction and increased PARP1 expression in cardiac macrophages. Inhibition of PARP1 by the PJ34 inhibitors could effectively alleviate M1 macrophage polarization, reduce infarction size, decrease inflammation and rescue the cardiac function post-MI in mice. Mechanistically, the suppression of PARP1 increase NLRC5 gene expression, and thus inhibits the NF-κB pathway, thereby decreasing the production of inflammatory cytokines such as IL-1β and TNF-α. Inhibition of NLRC5 promote infection by effectively abolishing the influence of this mechanism discussed above. Interestingly, inhibition of NLRC5 promotes cardiac macrophage polarization toward an M1 phenotype but without having major effects on M2 macrophages. Our results demonstrate that inhibition of PARP1 increased NLRC5 gene expression, thereby suppressing M1 polarization, improving cardiac function, decreasing infarct area and attenuating inflammatory injury. The aforementioned findings provide new insights into the proinflammatory mechanisms that drive macrophage polarization following myocardial infarction, thereby introducing novel potential targets for future therapeutic interventions in individuals affected by myocardial infarction.

The major histocompatibility complex class I (MHC class I)-mediated tumor antigen processing and presentation (APP) pathway is essential for the recruitment and activation of cytotoxic CD8+ T lymphocytes (CD8+ CTLs). However, this pathway is frequently dysregulated in many cancers, thus leading to a failure of immunotherapy. Here, we report that activation of the tumor-intrinsic Hippo pathway positively correlates with the expression of MHC class I APP genes and the abundance of CD8+ CTLs in mouse tumors and patients. Blocking the Hippo pathway effector Yes-associated protein/transcriptional enhanced associate domain (YAP/TEAD) potently improves antitumor immunity. Mechanistically, the YAP/TEAD complex cooperates with the nucleosome remodeling and deacetylase complex to repress NLRC5 transcription. The upregulation of NLRC5 by YAP/TEAD depletion or pharmacological inhibition increases the expression of MHC class I APP genes and enhances CD8+ CTL-mediated killing of cancer cells. Collectively, our results suggest a crucial tumor-promoting function of YAP depending on NLRC5 to impair the MHC class I APP pathway and provide a rationale for inhibiting YAP activity in immunotherapy for cancer.

BACKGROUND: Endothelial-to-Mesenchymal Transformation (EndMT) plays key roles in endothelial dysfunction during the pathological progression of atherosclerosis; however, its detailed mechanism remains unclear. Herein, we explored the biological function and mechanisms of upstream stimulating factor 1 (USF1) in EndMT during atherosclerosis.
METHODS: The in vivo and in vitro atherosclerotic models were established in high fat diet-fed ApoE-/- mice and ox-LDL-exposed human umbilical vein endothelial cells (HUVECs). The plaque formation, collagen and lipid deposition, and morphological changes in the aortic tissues were evaluated by hematoxylin and eosin (HE), Masson, Oil red O and Verhoeff-Van Gieson (EVG) staining, respectively. EndMT was determined by expression levels of EndMT-related proteins. Target molecule expression was detected by RT-qPCR and Western blotting. The release of pro-inflammatory cytokines was measured by ELISA. Migration of HUVECs was detected by transwell and scratch assays. Molecular mechanism was investigated by dual-luciferase reporter assay, ChIP, and Co-IP assays.
RESULTS: USF1 was up-regulated in atherosclerosis patients. USF1 knockdown inhibited EndMT by up-regulating CD31 and VE-Cadherin, while down-regulating α-SMA and vimentin, thereby repressing inflammation, and migration in ox-LDL-exposed HUVECs. In addition, USF1 transcriptionally activated ubiquitin-specific protease 14 (USP14), which promoted de-ubiquitination and up-regulation of NLR Family CARD Domain Containing 5 (NLRC5) and subsequent Smad2/3 pathway activation. The inhibitory effect of sh-USF1 or sh-USP14 on EndMT was partly reversed by USP14 or NLRC5 overexpression. Finally, USF1 knockdown delayed atherosclerosis progression via inhibiting EndMT in mice.
CONCLUSIONS: Our findings indicate the contribution of the USF1/USP14/NLRC5 axis to atherosclerosis development via promoting EndMT, which provide effective therapeutic targets.

Immunomodulatory effects of long-chain fatty acids (LCFAs) and their activating enzyme, acyl-coenzyme A (CoA) synthetase long-chain family (ACSL), in the tumor microenvironment remain largely unknown. Here, we find that ACSL5 functions as an immune-dependent tumor suppressor. ACSL5 expression sensitizes tumors to PD-1 blockade therapy in vivo and the cytotoxicity mediated by CD8+ T cells in vitro via regulation of major histocompatibility complex class I (MHC-I)-mediated antigen presentation. Through screening potential substrates for ACSL5, we further identify that elaidic acid (EA), a trans LCFA that has long been considered harmful to human health, phenocopies to enhance MHC-I expression. EA supplementation can suppress tumor growth and sensitize PD-1 blockade therapy. Clinically, ACSL5 expression is positively associated with improved survival in patients with lung cancer, and plasma EA level is also predictive for immunotherapy efficiency. Our findings provide a foundation for enhancing immunotherapy through either targeting ACSL5 or metabolic reprogramming of antigen presentation via dietary EA supplementation.

Microglia are believed to be the key immune effectors of the central immune microenvironment, and their dysregulation is associated with neuroinflammation and mood disorders. Nucleotide-binding oligomerization domain-like receptor family caspase recruitment domain-containing five (NLRC5) is a new member of the Nod-like receptor family. Recently, NLRC5 has been reported to be expressed by microglia. Nonetheless, the exact roles of NLRC5 in microglial activation and its function in depression have not been investigated yet. Herein, we found that reducing NLRC5 decreased lipopolysaccharide (LPS)-induced secretion of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) in primary cultured microglia and microglial cell lines but not in bone marrow-derived macrophages (BMDMs). In more detail, reducing NLRC5 diminished the secretion of LPS-induced cytokines by attenuating IKKα/β phosphorylation and inhibiting NF-κB signaling. Moreover, the expression of Nlrc5 in the hippocampus of LPS- or chronic unpredictable mild stress (CUMS)-induced depressive mice was increased. In line with the in vitro findings, Nlrc5 deficiency inhibited microglial activation in the mouse hippocampus and improved LPS- or CUMS-induced depressive-like behaviors. In summary, we demonstrated the critical role of NLRC5 in LPS-induced microglial activation and LPS- or CUMS-induced depressive mouse models.

Parkinson\'s disease (PD) is mainly characterized by the progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and neuroinflammation mediated by overactivated microglia and astrocytes. NLRC5 (nucleotide-binding oligomerization domain-like receptor family caspase recruitment domain containing 5) has been reported to participate in various immune disorders, but its role in neurodegenerative diseases remains unclear. In the current study, we found that the expression of NLRC5 was increased in the nigrostriatal axis of mice with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP)-induced PD, as well as in primary astrocytes, microglia and neurons exposed to different neurotoxic stimuli. In an acute MPTP-induced PD model, NLRC5 deficiency significantly reduced dopaminergic system degeneration and ameliorated motor deficits and striatal inflammation. Furthermore, we found that NLRC5 deficiency decreased the expression of the proinflammatory genes IL-1β, IL-6, TNF-α and COX2 in primary microglia and primary astrocytes treated with neuroinflammatory stimuli and reduced the inflammatory response in mixed glial cells in response to LPS treatment. Moreover, NLRC5 deficiency suppressed activation of the NF-κB and MAPK signaling pathways and enhanced the activation of AKT-GSK-3β and AMPK signaling in mixed glial cells. Furthermore, NLRC5 deficiency increased the survival of primary neurons treated with MPP+ or conditioned medium from LPS-stimulated mixed glial cells and promoted activation of the NF-κB and AKT signaling pathways. Moreover, the mRNA expression of NLRC5 was decreased in the blood of PD patients compared to healthy subjects. Therefore, we suggest that NLRC5 promotes neuroinflammation and dopaminergic degeneration in PD and may serve as a marker of glial activation.