Comparison of the cachexia index based on hand-grip strength (H-CXI) with the original CXI for the prediction of cancer cachexia and prognosis in patients who underwent radical colectomy for colorectal cancer.

Background and aims: The cachexia index (CXI) is a novel biomarker for estimating cancer cachexia. The cachexia index based on hand-grip strength (H-CXI) has been recently developed as a simple proxy for CXI. The present study aims to compare both the H-CXI and CXI for the prediction of cancer cachexia and postoperative outcomes in patients who underwent radical colectomy for colorectal cancer. Methods: Patients who underwent radical operations for colorectal cancer were included in this study. Cancer cachexia was diagnosed according to the international consensus outlined by Fearon et al. The cachexia index (CXI) was calculated as [skeletal muscle index (SMI) × serum albumin/neutrophil-to-lymphocyte ratio (NLR)]. The H-CXI was calculated as [hand-grip strength (HGS)/height2 × serum albumin/NLR]. The SMI was measured based on the preoperative CT images at the third lumbar vertebra (L3) level. HGS was measured before surgery. Results: From July 2014 to May 2021, a total of 1,411 patients were included in the present study, of whom 361 (25.6%) were identified as having cancer cachexia. Patients with cachexia had a lower CXI (p < 0.001) and lower H-CXI (p < 0.001) than those without cachexia. A low CXI but not low H-CXI independently predicted cancer cachexia in the multivariate analysis (OR 1.448, p = 0.024). Both a low CXI (HR 1.476, p < 0.001 for OS; HR 1.611, p < 0.001 for DFS) and low H-CXI (HR 1.369, p = 0.007 for OS; HR 1.642, p < 0.001 for DFS) were independent predictors for overall survival (OS) and disease-free survival (DFS) after adjusting for the same covariates. A low H-CXI but not low CXI was an independent risk factor for postoperative complications (OR 1.337, p = 0.044). No significant association was found between cancer cachexia and postoperative complications. Conclusion: The CXI and H-CXI exhibited better prognostic value than cancer cachexia for the prediction of postoperative outcomes in patients who underwent radical colectomy for colorectal cancer. The H-CXI was a superior index over the CXI in predicting short-term clinical outcomes, whereas the CXI demonstrated a closer correlation with Fearon's criteria for cancer cachexia. Ideal tools for the assessment of cancer cachexia should incorporate not only weight loss but also muscle mass, physical function, and inflammatory state.

Prognostic value of GLIM-defined malnutrition in combination with hand-grip strength or gait speed for the prediction of postoperative outcomes in gastric cancer patients with cachexia.

BACKGROUND: Cancer cachexia is associated with impaired functional and nutritional status and worse clinical outcomes. Global Leadership Initiative in Malnutrition (GLIM) consensus recommended the application of GLIM criteria to diagnose malnutrition in patients with cachexia. However, few previous study has applied the GLIM criteria in patients with cancer cachexia. METHODS: From July 2014 to May 2019, patients who were diagnosed with cancer cachexia and underwent radical gastrectomy for gastric cancer were included in this study. Malnutrition was diagnosed using the GLIM criteria. Skeletal muscle index was measured using abdominal computed tomography (CT) images at the third lumbar vertebra (L3) level. Hand-grip strength and 6-meters gait speed were measured before surgery. RESULTS: A total of 356 patients with cancer cachexia were included in the present study, in which 269 (75.56%) were identified as having malnutrition based on the GLIM criteria. GLIM-defined malnutrition alone did not show significant association with short-term postoperative outcomes, including complications, costs or length of postoperative hospital stays. The combination of low hand-grip strength or low gait speed with GLIM-defined malnutrition led to a significant predictive value for these outcomes. Moreover, low hand-grip strength plus GLIM-defined malnutrition was independently associated with postoperative complications (OR 1.912, 95% CI 1.151-3.178, P = 0.012). GLIM-defined malnutrition was an independent predictive factor for worse OS (HR 2.310, 95% CI 1.421-3.754, P = 0.001) and DFS (HR 1.815, 95% CI 1.186-2.779, P = 0.006) after surgery. The addition of low hand-grip strength or low gait speed to GLIM-defined malnutrition did not increase its predictive value for survival. CONCLUSION: GLIM-defined malnutrition predicted worse long-term survival in gastric cancer patients with cachexia. Gait speed and hand-grip strength added prognostic value to GLIM-defined malnutrition for the prediction of short-term postoperative outcomes, which could be incorporated into preoperative assessment protocols in patients with cancer cachexia.

SARS-CoV-2 infection establishes a stable and age-independent CD8+ T cell response against a dominant nucleocapsid epitope using restricted T cell receptors.

The resolution of SARS-CoV-2 replication hinges on cell-mediated immunity, wherein CD8+ T cells play a vital role. Nonetheless, the characterization of the specificity and TCR composition of CD8+ T cells targeting non-spike protein of SARS-CoV-2 before and after infection remains incomplete. Here, we analyzed CD8+ T cells recognizing six epitopes from the SARS-CoV-2 nucleocapsid (N) protein and found that SARS-CoV-2 infection slightly increased the frequencies of N-recognizing CD8+ T cells but significantly enhanced activation-induced proliferation compared to that of the uninfected donors. The frequencies of N-specific CD8+ T cells and their proliferative response to stimulation did not decrease over one year. We identified the N222-230 peptide (LLLDRLNQL, referred to as LLL thereafter) as a dominant epitope that elicited the greatest proliferative response from both convalescent and uninfected donors. Single-cell sequencing of T cell receptors (TCR) from LLL-specific CD8+ T cells revealed highly restricted Vα gene usage (TRAV12-2) with limited CDR3α motifs, supported by structural characterization of the TCR-LLL-HLA-A2 complex. Lastly, transcriptome analysis of LLL-specific CD8+ T cells from donors who had expansion (expanders) or no expansion (non-expanders) after in vitro stimulation identified increased chromatin modification and innate immune functions of CD8+ T cells in non-expanders. These results suggests that SARS-CoV-2 infection induces LLL-specific CD8+ T cell responses with a restricted TCR repertoire.

Comparisons of Drug-Eluting Balloon versus Drug-Eluting Stent in the Treatment of Young Patients with Acute Myocardial Infarction.

BACKGROUND: The incidence of acute myocardial infarction (AMI) in the younger population has been increasing gradually in recent years. The objective of the present study is to investigate the safety and effectiveness of drug-eluting balloons (DEBs) in young patients with AMI. METHODS: All consecutive patients with AMI aged ≤ 45 years were retrospectively enrolled. The primary endpoint was a device-oriented composite endpoint (DOCE) of cardiac death, target vessel myocardial infarction (MI), or target lesion revascularization (TLR). The secondary study endpoints included heart failure and major bleeding events. RESULTS: A total of 276 young patients presenting with AMI were finally included. The median follow-up period was 1155 days. Patients treated with DEBs had a trend toward a lower incidence of DOCEs (3.0% vs. 11.0%, p = 0.12) mainly driven by the need for TLR (3.0% vs. 9.1%, p = 0.19) than those treated with DESs. No significant differences between the two groups were detected in the occurrence of cardiac death (0.0% vs. 0.5%, p = 0.69), MI (0.0% vs. 1.4%, p = 0.40), heart failure (0.0% vs. 1.9%, p = 0.39), or major bleeding events (1.5% vs 4.8%, p = 0.30). Multivariate regression analysis showed that DEBs were associated with a trend toward a lower risk of DOCEs (HR 0.13, 95% CI [0.02, 1.05], p = 0.06). CONCLUSIONS: The findings of the present study suggested that DEBs might be a potential treatment option in young patients with AMI. A larger scale, randomized, multicenter study is required to investigate the safety and effectiveness of DEBs in this setting.

A Novel Reperfusion Strategy for Primary Percutaneous Coronary Intervention in Patients with Acute ST-Segment Elevation Myocardial Infarction: A Prospective Case Series.

BACKGROUND: Ischemia reperfusion injury (IRI) remains a major problem in patients with acute ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI). We have developed a novel reperfusion strategy for PCI and named it "volume-controlled reperfusion (VCR)". The aim of the current study was to assess the safety and feasibility of VCR in patients with STEMI. METHODS: Consecutive patients admitted to Beijing Chaoyang Hospital with STEMI were prospectively enrolled. The feasibility endpoint was procedural success. The safety endpoints included death from all causes, major vascular complications, and major adverse cardiac event (MACE), i.e., a composite of cardiac death, myocardial reinfarction, target vessel revascularization (TVR), and heart failure. RESULTS: A total of 30 patients were finally included. Procedural success was achieved in 28 (93.3%) patients. No patients died during the study and no major vascular complications or MACE occurred during hospitalization. With the exception of one patient (3.3%) who underwent TVR three months after discharge, no patient encountered death (0.0%), major vascular complications (0.0%), or and other MACEs (0.0%) during the median follow-up of 16 months. CONCLUSION: The findings of the pilot study suggest that VCR has favorable feasibility and safety in patients with STEMI. Further larger randomized trials are required to evaluate the effectiveness of VCR in STEMI patients.

Osr1 Regulates Macrophage-mediated Liver Inflammation in Nonalcoholic Fatty Liver Disease Progression.

BACKGROUND & AIMS: Liver macrophage-mediated inflammation contributes to the pathogenesis of the nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). Odd skipped-related 1 (Osr1) is a putative transcription factor previously reported to be involved in NASH progression; however, the underlying mechanisms remain unknown. The current study focused on the role of Osr1 in macrophage polarization and metabolism and its associated functions in the inflammation-induced pathogenesis of NASH. METHODS: OSR1/Osr1 expression patterns were compared in normal and NASH patients and mouse livers. NASH was established and compared between hepatocyte-specific Osr1 knockout (Osr1ΔHep), macrophage-specific Osr1 knockout (Osr1ΔMφ), and wild-type (Osr1F) mice fed with 3 different chronic obesogenic diets and methionine choline-deficient diet. Using genetic and therapeutic strategies in vitro and in vivo, the downstream targets of Osr1 and the associated mechanisms in inflammation-induced NASH were established. RESULTS: Osr1 was expressed in both hepatocytes and macrophages and exhibited different expression patterns in NASH. In NAFLD and NASH murine models, deleting Osr1 in myeloid cells (Osr1ΔMφ), but not hepatocytes, aggravated steatohepatitis with pronounced liver inflammation. Myeloid Osr1 deletion resulted in a polarization switch toward a pro-inflammatory phenotype associated with reduced oxidative phosphorylation activity. These inflamed Osr1ΔMφ macrophages promoted steatosis and inflammation in hepatocytes via cytokine secretion. We identified 2 downstream transcriptional targets of Osr1, c-Myc, and PPARγ and established the Osr1-PPARγ cascade in macrophage polarization and liver inflammation by genetic study and rosiglitazone treatment in vivo. We tested a promising intervention strategy targeting Osr1-PPARγ by AAV8L-delivered Osr1 expression or rosiglitazone that significantly repressed NAFLD/NASH progression in Osr1F and Osr1ΔMφ mice. CONCLUSIONS: Myeloid Osr1 mediates liver immune homeostasis and disrupting Osr1 aggravates the progression of NAFLD/NASH.

Offspring NAFLD liver phospholipid profiles are differentially programmed by maternal high-fat diet and maternal one carbon supplement.

Little is known if and how maternal diet affects the liver phospholipid profiles that contribute to non-alcoholic fatty liver disease (NAFLD) development in offspring. We examined NAFLD phenotypes in male offspring mice of either maternal normal-fat diet (NF group), maternal high-fat diet (HF group), maternal methionine supplement (H1S group), or complete one-carbon supplement (H2S group) added to the maternal HF diet during gestation and lactation. HF offspring displayed worsened NAFLD phenotypes induced by post-weaning HF diet, however, maternal one-carbon supplement prevented such outcome. HF offspring also showed a distinct phospholipid profile from the offspring exposed to H1S or H2S diet. Whole genome bisulfite sequencing (WGBS) analysis further identified five pathways involved in phospholipid metabolism altered by different maternal diet interventions. Furthermore, differential methylated regions (DMRs) on Prkca, Dgkh, Plcb1 and Dgki were identified comparing between HF and NF offspring; most of these DMRs were recovered in H2S offspring. These methylation pattern changes were associated with gene expression changes: HF diet significantly reduced while H1S and H2S diet recovered their levels. Maternal HF diet disrupted offspring phospholipid profiles contributing to worsened hepatic steatosis. The maternal one-carbon supplement prevented such effects, probably through DNA methylation modification.

Heterogeneity and transcriptome changes of human CD8+ T cells across nine decades of life.

The decline of CD8+ T cell functions contributes to deteriorating health with aging, but the mechanisms that underlie this phenomenon are not well understood. We use single-cell RNA sequencing with both cross-sectional and longitudinal samples to assess how human CD8+ T cell heterogeneity and transcriptomes change over nine decades of life. Eleven subpopulations of CD8+ T cells and their dynamic changes with age are identified. Age-related changes in gene expression result from changes in the percentage of cells expressing a given transcript, quantitative changes in the transcript level, or a combination of these two. We develop a machine learning model capable of predicting the age of individual cells based on their transcriptomic features, which are closely associated with their differentiation and mutation burden. Finally, we validate this model in two separate contexts of CD8+ T cell aging: HIV infection and CAR T cell expansion in vivo.

Holistic review and meta-analysis of independent impact of the residual SYNTAX score on prognosis in patients with acute coronary syndrome.

Objectives. The appropriate extent of revascularization following primary intervention is unknown. We conducted a systematic review and meta-analysis of residual Syntax score (rSS) to predict the outcomes and provide guide to optimal management of revascularization following primary intervention. Designs. Previously published studies from 2007 to 2020 assessing the prognostic impact of rSS after ACS were included for this meta-analysis. The primary endpoint was defined as the major adverse clinical events (MACE) in multivariable analysis. The risk ratios (RRs) with 95% confidence intervals (CI) were calculated using the RevMan 5.4 software. Results. A total of 8,157 participants complicated with ACS from 12 clinical studies were included in this analysis. Based on the wide range of rSS studies available, we classified it into two major groups: rSS < 8 and rSS ≥ 8. In multivariate analysis, the rSS was an independent risk marker for MACE [RR = 1.04 (95%CI; 1.00-1.08)], all-cause mortality [RR = 1.05 (1.03-1.07)] and cardiovascular death [RR = 1.05 (1.03-1.07)]. Patients with incomplete revascularization (ICR) showed higher prevalence of MACE along with all-cause mortality, cardiovascular morality, and recurrent myocardial infarction without significant heterogeneity [RR = 1.60 (1.03-1.07), 2.30 (1.57-3.38), 3.57 (2.09-6.10) and 1.70 (1.38-2.09), respectively]. The patients with rSS ≥ 8 presented higher frequency of all-cause mortality [RR = 2.99 (2.18-4.09)], cardiovascular death [RR = 3.32 (2.22-4.95)], and recurrent myocardial infarction [RR = 1.64 (1.34-2.02)]. Conclusion. The meta-analysis indicated that an rSS value of 8 could be a reasonable cut-off for incomplete revascularization after ACS and is an efficient tool to guide revascularization. In future, detailed research should focus on investigation of the optimal value of the rSS score.

Maternal One-Carbon Supplement Reduced the Risk of Non-Alcoholic Fatty Liver Disease in Male Offspring.

Recent studies have suggested that prevention of obesity and non-alcoholic fatty liver disease (NAFLD) should start with maternal dietary management. We previously reported disrupted methionine cycle, associated with NAFLD, in male offspring liver due to maternal high-fat (HF) diet, thus we hypothesize that maternal one-carbon supplement may reduce the risk of NAFLD in offspring via the normalizing methionine cycle. To test it, female mice (F0) were exposed to either a maternal normal-fat diet (NF group) a maternal HF diet (HF group), or a maternal methyl donor supplement (H1S or H2S group) during gestation and lactation. The offspring male mice (F1) were exposed to a postweaning HF diet to promote NAFLD. While the HF offspring displayed obesity, glucose intolerance and hepatic steatosis, the H1S and H2S offspring avoided hepatic steatosis. This phenotype was associated with the normalization of the methionine cycle and the restoration of L-carnitine and AMPK activity. Furthermore, maternal HF diet induced epigenetic regulation of important genes involved in fatty acid oxidation and oxidative phosphorylation via DNA methylation modifications, which were recovered by maternal one-carbon supplementation. Our study provides evidence that maternal one-carbon supplement can reverse/block the adverse effects of maternal HF diet on promoting offspring NAFLD, suggesting a potential nutritional strategy that is administered to mothers to prevent NAFLD in the offspring.

Maternal high-fat diet disrupted one-carbon metabolism in offspring, contributing to nonalcoholic fatty liver disease.

BACKGROUND & AIMS: Pregnant women may transmit their metabolic phenotypes to their offspring, enhancing the risk for nonalcoholic fatty liver disease (NAFLD); however, the molecular mechanisms remain unclear. METHODS: Prior to pregnancy female mice were fed either a maternal normal-fat diet (NF-group, "no effectors"), or a maternal high-fat diet (HF-group, "persistent effectors"), or were transitioned from a HF to a NF diet before pregnancy (H9N-group, "effectors removal"), followed by pregnancy and lactation, and then offspring were fed high-fat diets after weaning. Offspring livers were analysed by functional studies, as well as next-generation sequencing for gene expression profiles and DNA methylation changes. RESULTS: The HF, but not the H9N offspring, displayed glucose intolerance and hepatic steatosis. The HF offspring also displayed a disruption of lipid homeostasis associated with an altered methionine cycle and abnormal one-carbon metabolism that caused DNA hypermethylation and L-carnitine depletion associated with deactivated AMPK signalling and decreased expression of PPAR-α and genes for fatty acid oxidation. These changes were not present in H9N offspring. In addition, we identified maternal HF diet-induced genes involved in one-carbon metabolism that were associated with DNA methylation modifications in HF offspring. Importantly, the DNA methylation modifications and their associated gene expression changes were reversed in H9N offspring livers. CONCLUSIONS: Our results demonstrate for the first time that maternal HF diet disrupted the methionine cycle and one-carbon metabolism in offspring livers which further altered lipid homeostasis. CpG islands of specific genes involved in one-carbon metabolism modified by different maternal diets were identified.

Osr1 regulates hepatic inflammation and cell survival in the progression of non-alcoholic fatty liver disease.

Odd-skipped related 1 (Osr1) is a novel tumor suppressor gene in several cancer cell lines. Non-alcoholic steatohepatitis (NASH) is considered as a high-risk factor for hepatocellular carcinoma (HCC). This study is aimed to investigate the novel role of Osr1 in promoting the progression of hepatic steatosis to NASH. Following 12 weeks of diethylnitrosamine (DEN) and high-fat diet (HFD), wildtype (WT) and Osr1 heterozygous (Osr1+/-) male mice were examined for liver injuries. Osr1+/- mice displayed worsen liver injury with higher serum alanine aminotransferase levels than the WT mice. The Osr1+/- mice also revealed early signs of collagen deposition with increased hepatic Tgfb and Fn1 expression. There was overactivation of both JNK and NF-κB signaling in the Osr1+/- liver, along with accumulation of F4/80+ cells and enhanced hepatic expression of Il-1b and Il-6. Moreover, the Osr1+/- liver displayed hyperphosphorylation of AKT/mTOR signaling, associated with overexpression of Bcl-2. In addition, Osr1+/- and WT mice displayed differences in the DNA methylome of the liver cells. Specifically, Osr1-responsible CpG islands of Ccl3 and Pcgf2, genes for inflammation and macrophage infiltration, were further identified. Taken together, Osr1 plays an important role in regulating cell inflammation and survival through multiple signaling pathways and DNA methylation modification for NAFLD progression.

Lipid Microbubble-Conjugated Anti-CD3 and Anti-CD28 Antibodies (Microbubble-Based Human T Cell Activator) Offer Superior Long-Term Expansion of Human Naive T Cells In Vitro.

Stimulation of human primary T cells with immobilized anti-CD3 and anti-CD28 Abs in vitro provide a system to study T cell activation and proliferation and an avenue for expanding T cells for immunotherapy. Magnetic beads conjugated with anti-CD3 and anti-CD28 Abs (Dynabeads Human T-Activator [D-TCA]) have been a golden standard for stimulating human primary T cells in vitro. In this study, we report that an application using anti-CD3 and anti-CD28 Abs conjugated on lipid microbubbles (microbubble-based human T cell activator [MB-TCA]) to stimulate primary human naive T cells resulted in expansion superior to D-TCA. In 56-d cultures with three repeated stimulation cycles (14 d per stimulation), we found that 1) MB-TCA induced significantly better expansion (20- and 10-fold increase) of naive CD4+ and CD8+ T cells than did D-TCA; 2) MB-TCA- and D-TCA-stimulated T cells had a similar number of initial cell divisions, but MB-TCA had significantly lower activation-induced cell death than D-TCA; 3) MB-TCA-stimulated T cells produced less TNF-α than did D-TCA; and 4) blocking TNF-α action via adding an Ab against TNF-αR (TNFRSF1A) significantly improved expansion of T cells activated by D-TCA in vitro. Together, we demonstrated that the MB-TCA induces a better expansion of human naive T cells in vitro and offers advantages in both basic and clinical applications in which the outcome depends on the number of T cells.

The zebrafish NLRP3 inflammasome has functional roles in ASC-dependent interleukin-1ß maturation and gasdermin E-mediated pyroptosis.

The NLR family pyrin domain containing 3 (NLRP3) inflammasome is one of the best-characterized inflammasomes in humans and other mammals. However, knowledge about the NLRP3 inflammasome in nonmammalian species remains limited. Here, we report the molecular and functional identification of an NLRP3 homolog (DrNLRP3) in a zebrafish (Danio rerio) model. We found that DrNLRP3's overall structural architecture was shared with mammalian NLRP3s. It initiates a classical inflammasome assembly for zebrafish inflammatory caspase (DrCaspase-A/-B) activation and interleukin 1ß (DrIL-1ß) maturation in an apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC)-dependent manner, in which DrNLRP3 organizes DrASC into a filament that recruits DrCaspase-A/-B by homotypic pyrin domain (PYD)-PYD interactions. DrCaspase-A/-B activation in the DrNLRP3 inflammasome occurred in two steps, with DrCaspase-A being activated first and DrCaspase-B second. DrNLRP3 also directly activated full-length DrCaspase-B and elicited cell pyroptosis in a gasdermin E (GSDME)-dependent but ASC-independent manner. These two events were tightly coordinated by DrNLRP3 to ensure efficient IL-1ß secretion for the initiation of host innate immunity. By knocking down DrNLRP3 in zebrafish embryos and generating a DrASC-knockout (DrASC-/-) fish clone, we characterized the function of the DrNLRP3 inflammasome in anti-bacterial immunity in vivo The results of our study disclosed the origin of the NLRP3 inflammasome in teleost fish, providing a cross-species understanding of the evolutionary history of inflammasomes. Our findings also indicate that the NLRP3 inflammasome may coordinate inflammatory cytokine processing and secretion through a GSDME-mediated pyroptotic pathway, uncovering a previously unrecognized regulatory function of NLRP3 in both inflammation and cell pyroptosis.

Maternal diet intervention before pregnancy primes offspring lipid metabolism in liver.

Nonalcoholic fatty liver disease (NAFLD) has a developmental origin and is influenced in utero. We aimed to evaluate if maternal diet intervention before pregnancy would be beneficial to reduce the risk of offspring NAFLD. In our study, female mice were either on a normal-fat diet (NF group), or a high-fat diet for 12 weeks and continued on this diet throughout pregnancy and lactation (HF group), or switched from HF-to-NF diet 1 week (H1N group), or 9 weeks (H9N group) before pregnancy. Compared with the NF offspring, the H1N and HF, but not the H9N offspring, displayed more severe hepatic steatosis and glucose intolerance. More specifically, an abnormal blood lipid panel was seen in the H1N offspring and abnormal hepatic free fatty acid composition was present in both the HF and H1N offspring, while the H9N offspring displayed both at normal levels. These physiological changes were associated with desensitized hepatic insulin/AKT signaling, increased expression of genes and proteins for de novo lipogenesis and cholesterol synthesis, decreased expression of genes and proteins for fatty acid oxidation, increased Pcsk9 expression, and hypoactivation of 5' AMP-activated protein kinase (AMPK) signaling in the HF and H1N offspring. However, these effects were completely or partially rescued in the H9N offspring. In summary, we found that early maternal diet intervention is effective in reducing the risk of offspring NAFLD caused by maternal HF diet. These findings provide significant support to develop effective diet intervention strategies and policies for prevention of obesity and NAFLD to promote optimal health outcomes for mothers and children.

The Interplay Between Pattern Recognition Receptors and Autophagy in Inflammation.

Pattern recognition receptors (PRRs) are sensors of exogenous and endogenous "danger" signals from pathogen-associated molecular patterns (PAMPs), and damage associated molecular patterns (DAMPs), while autophagy can respond to these signals to control homeostasis. Almost all PRRs can induce autophagy directly or indirectly. Toll-like receptors (TLRs), Nod-like receptors (NLRs), retinoic acid-inducible gene-I-like receptors (RLRs), and cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon genes (STING) pathway can induce autophagy directly through Beclin-1 or LC3-dependent pathway, while the interactions with the receptor for advanced glycation end products (RAGE)/high mobility group box 1 (HMGB1), CD91/Calreticulin, and TLRs/HSPs are achieved by protein, Ca2+, and mitochondrial homeostasis. Autophagy presents antigens to PRRs and helps to clean the pathogens. In addition, the induced autophagy can form a negative feedback regulation of PRRs-mediated inflammation in cell/disease-specific manner to maintain homeostasis and prevent excessive inflammation. Understanding the interaction between PRRs and autophagy in a specific disease will promote drug development for immunotherapy. Here, we focus on the interactions between PRRs and autophagy and how they affect the inflammatory response.

BTLA-HVEM Checkpoint Axis Regulates Hepatic Homeostasis and Inflammation in a ConA-Induced Hepatitis Model in Zebrafish.

The BTLA-HVEM checkpoint axis plays extensive roles in immunomodulation and diseases, including cancer and autoimmune disorders. However, the functions of this checkpoint axis in hepatitis remain limited. In this study, we explored the regulatory role of the Btla-Hvem axis in a ConA-induced hepatitis model in zebrafish. Results showed that Btla and Hvem were differentially expressed on intrahepatic Cd8+ T cells and hepatocytes. Knockdown of Btla or Hvem significantly promoted hepatic inflammation. Btla was highly expressed in Cd8+ T cells in healthy liver but was downregulated in inflamed liver, as evidenced by a disparate proportion of Cd8+Btla+ and Cd8+Btla- T cells in individuals without or with ConA stimulation. Cd8+Btla+ T cells showed minimal cytotoxicity to hepatocytes, whereas Cd8+Btla- T cells were strongly reactive. The depletion of Cd8+Btla- T cells reduced hepatitis, whereas their transfer enhanced hepatic inflammation. These observations indicate that Btla endowed Cd8+Btla+ T cells with self-tolerance, thereby preventing them from attacking hepatocytes. Btla downregulation deprived this tolerization. Mechanistically, Btla-Hvem interaction contributed to Cd8+Btla+ T cell tolerization, which was impaired by Hvem knockdown but rescued by soluble Hvem protein administration. Notably, Light was markedly upregulated on Cd8+Btla- T cells, accompanied by the transition of Cd8+Btla+Light- to Cd8+Btla-Light+ T cells during hepatitis, which could be modulated by Cd4+ T cells. Light blockade attenuated hepatitis, thereby suggesting the positive role of Light in hepatic inflammation. These findings provide insights into a previously unrecognized Btla-Hvem-Light regulatory network in hepatic homeostasis and inflammation, thus adding a new potential therapeutic intervention for hepatitis.

Characterization of an NLRP1 Inflammasome from Zebrafish Reveals a Unique Sequential Activation Mechanism Underlying Inflammatory Caspases in Ancient Vertebrates.

NLRP1 inflammasome is one of the best-characterized inflammasomes in humans and other mammals. However, the existence of this inflammasome in nonmammalian species remains poorly understood. In this study, we report the molecular and functional identification of an NLRP1 homolog, Danio rerio NLRP1 (DrNLRP1) from a zebrafish (D. rerio) model. This DrNLRP1 possesses similar structural architecture to mammalian NLRP1s. It can trigger the formation of a classical inflammasome for the activation of zebrafish inflammatory caspases (D. rerio Caspase [DrCaspase]-A and DrCaspase-B) and maturation of D. rerio IL-1ß in a D. rerio ASC (DrASC)-dependent manner. In this process, DrNLRP1 promotes the aggregation of DrASC into a filament with DrASCCARD core and DrASCPYD cluster. The assembly of DrNLRP1 inflammasome depends on the CARD-CARD homotypic interaction between DrNLRP1 and DrASCCARD core, and PYD-PYD interaction between DrCaspase-A/B and DrASCPYD cluster. The FIIND domain in DrNLRP1 is necessary for inflammasome assembly. To understand the mechanism of how the two DrCaspases are coordinated in DrNLRP1 inflammasome, we propose a two-step sequential activation model. In this model, the recruitment and activation of DrCaspase-A/B in the inflammasome is shown in an alternate manner, with a preference for DrCaspase-A followed by a subsequent selection for DrCaspase-B. By using morpholino oligonucleotide-based knockdown assays, the DrNLRP1 inflammasome was verified to play important functional roles in antibacterial innate immunity in vivo. These observations demonstrate that the NLRP1 inflammasome originated as early as in teleost fish. This finding not only gives insights into the evolutionary history of inflammasomes but also provides a favorable animal model for the study of NLRP1 inflammasome-mediated immunology and diseases.

Identification of DEAD-Box RNA Helicase DDX41 as a Trafficking Protein That Involves in Multiple Innate Immune Signaling Pathways in a Zebrafish Model.

DDX41 is an important sensor for host recognition of DNA viruses and initiation of nuclear factor-κB (NF-κB) and IFN signaling pathways in mammals. However, its occurrence and functions in other vertebrates remain poorly defined. Here, a DDX41 ortholog [Danio rerio DDX41 (DrDDX41)] with various conserved structural features to its mammalian counterparts was identified from a zebrafish model. This DrDDX41 was found to be a trafficking protein distributed in the nucleus of resting cells but transported into the cytoplasm under DNA stimulation. Two nuclear localization signal motifs were localized beside the coiled-coil domain, whereas one nuclear export signal motif existed in the DEADc domain. DrDDX41 acts as an initiator for the activation of NF-κB and IFN signaling pathways in a Danio rerio STING (DrSTING)-dependent manner through its DEADc domain, which is a typical performance of mammalian DDX41. These observations suggested the conservation of DDX41 proteins throughout the vertebrate evolution, making zebrafish an alternative model in understanding DDX41-mediated immunology. With this model system, we found that DrDDX41 contributes to DrSTING-Danio rerio STAT6 (DrSTAT6)-mediated chemokine (Danio rerio CCL20) production through its DEADc domain. To the best of our knowledge, this work is the first report showing that DDX41 is an upstream initiator in this newly identified signaling pathway. The DrDDX41-mediated signaling pathways play important roles in innate antibacterial immunity because knockdown of either DrDDX41 or DrSTING/DrSTAT6 significantly reduced the survival of zebrafish under Aeromonas hydrophilia or Edwardsiella tarda infection. Our findings would enrich the current knowledge of DDX41-mediated immunology and the evolutionary history of the DDX41 family.

Peroxiredoxin 1 (Prx1) is a dual-function enzyme by possessing Cys-independent catalase-like activity.

Peroxiredoxin (Prx) was previously known as a Cys-dependent thioredoxin. However, we unexpectedly observed that Prx1 from the green spotted puffer fish Tetraodon nigroviridis (TnPrx1) was able to reduce H2O2 in a manner independent of Cys peroxidation and reductants. This study aimed to validate a novel function for Prx1, delineate the biochemical features and explore its antioxidant role in cells. We have confirmed that Prx1 from the puffer fish and humans truly possesses a catalase (CAT)-like activity that is independent of Cys residues and reductants, but dependent on iron. We have identified that the GVL motif was essential to the CAT-like activity of Prx1, but not to the Cys-dependent thioredoxin peroxidase (POX) activity, and generated mutants lacking POX and/or CAT-like activities for individual functional validation. We discovered that the TnPrx1 POX and CAT-like activities possessed different kinetic features in the reduction of H2O2 The overexpression of wild-type TnPrx1 and mutants differentially regulated the intracellular levels of reactive oxygen species (ROS) and the phosphorylation of p38 in HEK-293T cells treated with H2O2 Prx1 is a dual-function enzyme by acting as POX and CAT with varied affinities towards ROS. This study extends our knowledge on Prx1 and provides new opportunities to further study the biological roles of this family of antioxidants.