NR4A1 suppresses pyroptosis by transcriptionally inhibiting NLRP3 and IL-1β and co-localizing with NLRP3 in trans-Golgi to alleviate pathogenic bacteria-induced colitis

Nur77 as a novel regulator of Paneth cell differentiation and function

Serving as a part of intestinal innate immunity, Paneth cells play an important role in intestinal homeostasis maintenance via their multiple functions. However, the regulation of Paneth cells has been proven to be complex and diverse. Here, we identified nuclear receptor Nur77 as a novel regulator of Paneth cell differentiation and function. Nur77 deficiency led to the loss of Paneth cells in murine ileal crypts. Intestinal tissues or organoids with Nur77 deficiency exhibited the impaired intestinal stem cell niche and failed to enhance antimicrobial peptide expression after Paneth cell degranulation. The defects in Paneth cells and antimicrobial peptides in Nur7-/- mice led to intestinal microbiota disorders. Nur77 deficiency rendered postnatal mice susceptible to necrotizing enterocolitis. Mechanistically, Nur77 transcriptionally inhibited Dact1 expression to activate Wnt signaling activity, thus promoting Paneth cell differentiation and function. Taken together, our data suggest the regulatory role of Nur77 in Paneth cell differentiation and function and reveal a novel Dact1-mediated Wnt inhibition mechanism in Paneth cell development.

Machine learning reveals PANoptosis as a potential reporter and prognostic revealer of tumour microenvironment in lung adenocarcinoma

Lung adenocarcinoma (LUAD), a prominent lung cancer subtype, has an underexplored relationship with PANoptosis, a recently discovered mode of tumour cell death. This study incorporated iron death, copper death, scorch death, necrotizing apoptosis and bisulfide death into a pan-death gene set (PANoptosis) and conducted single-cell analysis of scRNA-seq data from 11 LUAD samples. Differentially expressed genes were identified, and Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed. Univariate COX regression and least absolute shrinkage and selection operator (LASSO) regression were used to screen PANoptosis key genes for constructing an LUAD risk model. The model's prognostic performance was evaluated using survival curves, risk scores and validation in the Gene Expression Omnibus database. The study also explored the correlation between risk scores, tumour biological function, immunotherapy, drug sensitivity and immune infiltration. The SMS gene in the PANoptosis model was silenced in two LUAD cell lines for cellular validation. Single-cell analysis revealed eight major cell types and several PANoptosis genes significantly associated with LUAD survival. The risk model demonstrated strong prognostic performance and association with immune infiltration, suggesting PANoptosis involvement in LUAD tumour immunity. Cellular validation further supported these findings. The PANoptosis key risk genes are believed to be closely related to the tumour microenvironment and immune regulation of LUAD, potentially providing valuable insights for early diagnosis and clinical treatment, and broader applications in other tumours and complex diseases.

Recent updates on pyroptosis in tumors of the digestive tract

Pyroptosis is an inflammasome-dependent form of programmed cell death that is mediated by caspases-1, -4, -5, and -11, and the gasdermin protein family. It is characterized by the rupture of cell membrane and the subsequent release of cell contents and interleukins, leading to inflammatory reaction and activation of the immune system. Recent studies have suggested that pyroptosis plays a role in the development of gastrointestinal tumors, impeding tumor generation and progression as well as providing a favorable microenvironment for tumor growth. In this review we outlined the current knowledge regarding the implications of pyroptosis in gastrointestinal cancers.

Design, synthesis fusidic acid derivatives alleviate acute lung injury via inhibiting MAPK/NF-κB/NLRP3 pathway

Acute lung injury (ALI) refers to a series of lung lesions resulting from multiple lung injuries, even leading to morbidity and death, abundant previous reports have showed that anti-inflammatory as a key to treatment of ALI. Fusidic acid (FA) as an antibiotic has significant anti-bacterial activity and anti-inflammatory effects. In this study, we designed and synthesized 34 FA derivatives to identify new anti-inflammatory drugs. The anti-inflammatory activities of the derivatives were screened using lipopolysaccharide (LPS)-induced RAW264.7 cells to evaluate the anti-inflammatory activity of the compounds, we measured nitric oxide (NO) and interleukin-6 (IL-6). Most of compounds showed inhibitory effects on inflammatory NO and IL-6 in LPS-induced RAW264.7 cells. Based on the screening results, compound a1 showed the strongest anti-inflammatory activity. Compared with FA, the inhibition rate NO and IL-6 of compound a1 increased 3.08 and 2.09 times at 10 μM, respectively. We further measured a1 inhibited inflammatory factor NO (IC50 = 3.26 ± 0.42 μM), IL-6 (IC50 = 1.85 ± 0.21 μM) and TNF-α (IC50 = 3.88 ± 0.55 μM). We also demonstrated that a1 markedly inhibits the expression of certain immune-related cytotoxic factors, including cyclooxygenase-2 (COX-2) and inducible nitric-oxide synthase (iNOS). In vivo results indicate that a1 can reduce lung inflammation and NO, IL-6, TNF-α, COX-2 and iNOS in LPS-induced ALI mice. On the one hand, we demonstrated a1 inhibits the mitogen-activated protein kinase (MAPK) signaling pathway by down-regulating the phosphorylation of p38 MAPK, c-Jun N-terminal kinase (c-JNK) and extracellular signal-regulated kinase (ERK). Moreover, a1 also suppressing the phosphorylation of inhibitory NF-κB inhibitor α (IκBα) inhibits the activation of the nuclear factor-κB (NF-κB) signaling pathway. On the other hand, we demonstrated a1 also role in anti-inflammatory by inhibits nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3) inflammasome and further inhibits Caspase-1 and inflammatory factor interleukin-1β (IL-1β). In conclusion, our study demonstrates that a1 has an anti-inflammatory effect and alleviates ALI by regulating inflammatory mediators and suppressing the MAPK, NF-κB and NLRP3 inflammasome signaling pathways.

The Induction Mechanism of Ferroptosis, Necroptosis, and Pyroptosis in Inflammatory Bowel Disease, Colorectal Cancer, and Intestinal Injury

Cell death includes programmed and nonprogrammed cell death. The former mainly includes ferroptosis, necroptosis, pyroptosis, autophagy, and apoptosis, while the latter refers to necrosis. Accumulating evidence shows that ferroptosis, necroptosis, and pyroptosis play essential regulatory roles in the development of intestinal diseases. In recent years, the incidence of inflammatory bowel disease (IBD), colorectal cancer (CRC), and intestinal injury induced by intestinal ischemia-reperfusion (I/R), sepsis, and radiation have gradually increased, posing a significant threat to human health. The advancement in targeted therapies for intestinal diseases based on ferroptosis, necroptosis, and pyroptosis provides new strategies for treating intestinal diseases. Herein, we review ferroptosis, necroptosis, and pyroptosis with respect to intestinal disease regulation and highlight the underlying molecular mechanisms for potential therapeutic applications.

Nur77 influences immunometabolism to regulate the release of proinflammatory cytokines and the formation of lipid bodies during Mycobacterium tuberculosis infection of macrophages

Infection of macrophages with Mycobacterium tuberculosis induces innate immune responses designed to clear the invading bacterium. However, bacteria often survive within the intracellular environment by exploiting these responses triggered by macrophages. Here, the role of the orphan nuclear receptor Nur77 (Nr4a1) in regulating the response of macrophages infected with M. tuberculosis (Mtb) has been delineated. Nur77 is induced early during infection, regulates metabolism by binding directly at the promoter of the TCA cycle enzyme, isocitrate dehydrogenase 2 (IDH2), to act as its repressor, and shifts the balance from a proinflammatory to an anti-inflammatory phenotype. Depletion of Nur77 increased transcription of IDH2 and, consequently, the levels of intracellular succinate, leading to enhanced levels of the proinflammatory cytokine IL-1β. Further, Nur77 inhibited the production of antibacterial nitric oxide and IL-1β in a succinate dehydrogenase (SDH)-dependent manner, suggesting that its induction favors bacterial survival by suppressing bactericidal responses. Indeed, depletion of Nur77 inhibited the intracellular survival of Mtb. On the other hand, depletion of Nur77 enhanced lipid body formation, suggesting that the fall in Nur77 levels as infection progresses likely favors foamy macrophage formation and long-term survival of Mtb in the host milieu.