Meteorin-like protein/METRNL/Interleukin-41 ameliorates atopic dermatitis-like inflammation.

BACKGROUND: Meteorin-like protein (METRNL)/Interleukin-41 (IL-41) is a novel immune-secreted cytokine/myokine involved in several inflammatory diseases. However, how METRNL exerts its regulatory properties on skin inflammation remains elusive. This study aims to elucidate the functionality and regulatory mechanism of METRNL in atopic dermatitis (AD). METHODS: METRNL levels were determined in skin and serum samples from patients with AD and subsequently verified in the vitamin D3 analogue MC903-induced AD-like mice model. The cellular target of METRNL activity was identified by multiplex immunostaining, single-cell RNA-seq and RNA-seq. RESULTS: METRNL was significantly upregulated in lesions and serum of patients with dermatitis compared to healthy controls (p <.05). Following repeated MC903 exposure, AD model mice displayed elevated levels of METRNL in both ears and serum. Administration of recombinant murine METRNL protein (rmMETRNL) ameliorated allergic skin inflammation and hallmarks of AD in mice, whereas blocking of METRNL signaling led to the opposite. METRNL enhanced ß-Catenin activation, limited the expression of Th2-related molecules that attract the accumulation of Arginase-1 (Arg1)hi macrophages, dendritic cells, and activated mast cells. CONCLUSIONS: METRNL can bind to KIT receptor and subsequently alleviate the allergic inflammation of AD by inhibiting the expansion of immune cells, and downregulating inflammatory gene expression by regulating the level of active WNT pathway molecule ß-Catenin.

Senescence defines a distinct subset of myofibroblasts that orchestrates immunosuppression in pancreatic cancer.

PDAC therapeutic resistance is largely attributed to a unique tumor microenvironment embedded with an abundance of cancer associated fibroblasts (CAFs). Distinct CAF populations were recently identified, but the phenotypic drivers and specific impact of CAF heterogeneity remain unclear. In this study, we identify a subpopulation of senescent myofibroblastic CAFs (SenCAFs) in mouse and human PDAC. These SenCAFs are a phenotypically distinct subset of myofibroblastic CAFs that localize near tumor ducts and accumulate with PDAC progression. To assess the impact of endogenous SenCAFs in PDAC, we employed a LSL-KRASG12D;p53flox;p48-CRE;INK-ATTAC (KPPC-IA) mouse model of spontaneous PDAC with inducible senescent cell depletion. Depletion of senescent stromal cells in genetic and pharmacologic PDAC models relieved immune suppression by macrophages, delayed tumor progression and increased responsiveness to chemotherapy. Collectively, our findings demonstrate that SenCAFs promote PDAC progression and immune cell dysfunction.

Decreased HMGCS1 inhibits proliferation and inflammatory response of keratinocytes and ameliorates imiquimod-induced psoriasis via the STAT3/IL-23 axis.

Psoriasis is an immuno-inflammatory disease characterized by excessive keratinocyte proliferation, requiring extensive lipids. 3-hydroxy-3-methylglutaryl-coenzyme A synthase 1 (HMGCS1) is an essential enzyme in the mevalonate pathway, involved in cholesterol synthesis and the inflammatory response. However, the role of HMGCS1 in psoriasis has remained elusive. This study aims to elucidate the mechanism by which HMGCS1 controls psoriasiform inflammation. We discovered an increased abundance of HMGCS1 in psoriatic lesions when analyzing two Gene Expression Omnibus (GEO) datasets and confirmed this in psoriatic animal models and psoriatic patients by immunohistochemistry. In a TNF-α stimulated psoriatic HaCaT cell line, HMGCS1 was found to be overexpressed. Knockdown of HMGCS1 using siRNA suppressed the migration and proliferation of HaCaT cells. Mechanistically, HMGCS1 downregulation also reduced the expression of IL-23 and the STAT3 phosphorylation level. In imiquimod-induced psoriatic mice, intradermal injection of HMGCS1 siRNA significantly decreased the expression of HMGCS1 in the epidermis, which in turn led to an improvement in the Psoriasis Area and Severity Index score, epidermal thickening, and pathological Baker score. Additionally, expression levels of inflammatory cytokines IL-23, IL1-ß, chemokine CXCL1, and innate immune mediator S100A7-9 were downregulated in the epidermis. In conclusion, HMGCS1 downregulation improved psoriasis in vitro and in vivo through the STAT3/IL-23 axis.

"RIPping" off Pancreas Cancer's Blockage of Immune Surveillance.

SUMMARY: MHC-I downregulation is correlated with immunotherapy resistance in PDAC, but efficient strategies to increase cell-surface MHC-I are still lacking. This study by Sang, Zhou, Chen, Yu, and colleagues identified inhibition of tumor-intrinsic RIPK2 as a pharmacologic target to block the degradation of MHC-I on tumor cells and improved PDAC responses to anti-PD-1 immunotherapy. See related article by Sang et al., p. 326 (1) .

Epigenetic regulation during cancer transitions across 11 tumour types.

Chromatin accessibility is essential in regulating gene expression and cellular identity, and alterations in accessibility have been implicated in driving cancer initiation, progression and metastasis1-4. Although the genetic contributions to oncogenic transitions have been investigated, epigenetic drivers remain less understood. Here we constructed a pan-cancer epigenetic and transcriptomic atlas using single-nucleus chromatin accessibility data (using single-nucleus assay for transposase-accessible chromatin) from 225 samples and matched single-cell or single-nucleus RNA-sequencing expression data from 206 samples. With over 1 million cells from each platform analysed through the enrichment of accessible chromatin regions, transcription factor motifs and regulons, we identified epigenetic drivers associated with cancer transitions. Some epigenetic drivers appeared in multiple cancers (for example, regulatory regions of ABCC1 and VEGFA; GATA6 and FOX-family motifs), whereas others were cancer specific (for example, regulatory regions of FGF19, ASAP2 and EN1, and the PBX3 motif). Among epigenetically altered pathways, TP53, hypoxia and TNF signalling were linked to cancer initiation, whereas oestrogen response, epithelial-mesenchymal transition and apical junction were tied to metastatic transition. Furthermore, we revealed a marked correlation between enhancer accessibility and gene expression and uncovered cooperation between epigenetic and genetic drivers. This atlas provides a foundation for further investigation of epigenetic dynamics in cancer transitions.

TNF-α promotes CXCL-1/8 production in keratinocytes by downregulating galectin-3 through NF-κB and hsa-miR-27a-3p pathway to contribute psoriasis development.

OBJECTIVE: Treatment with TNF-α inhibitors improve psoriasis with minimize/minor neutrophils infiltration and CXCL-1/8 expression in psoriatic lesions. However, the fine mechanism of TNF-α initiating psoriatic inflammation by tuning keratinocytes is unclear. Our previous research identified the deficiency of intracellular galectin-3 was sufficient to promote psoriasis inflammation characterized by neutrophil accumulation. This study aims to investigate whether TNF-α participated in psoriasis development through dysregulating galectin-3 expression. METHODS: mRNA levels were assessed through quantitative real-time PCR. Flow cytometry was used to detect cell cycle/apoptosis. Western blot was used to evaluate the activation of the NF-κB signaling pathway. HE staining and immunochemistry were used to detect epidermal thickness and MPO expression, respectively. Specific small interfering RNA (siRNA) was used to knock down hsa-miR-27a-3p while plasmids transfection was used to overexpress galectin-3. Further, the multiMiR R package was utilized to predict microRNA-target interaction. RESULTS AND DISCUSSION: We found that TNF-α stimulation altered cell proliferation and differentiation and promoted the production of psoriasis-related inflammatory mediators along with the inhibition of galectin-3 expression in keratinocytes. Supplement of galectin-3 could counteract the rise of CXCL-1/8 but not the other phenotypes of keratinocytes induced by TNF-α. Mechanistically, inhibition of the NF-κB signaling pathway could counteract the decrease of galectin-3 and the increase of hsa-miR-27a-3p expression whereas silence of hsa-miR-27a-3p could counteract the decrease of galectin-3 expression induced by TNF-α treatment in keratinocytes. Intradermal injection of murine anti-CXCL-2 antibody greatly alleviated imiquimod-induced psoriasis-like dermatitis. CONCLUSION: TNF-α initiates psoriatic inflammation by increasing CXCL-1/8 in keratinocytes mediated by the axis of NF-κB-hsa-miR-27a-3p-galectin-3 pathway.

Context-dependent activation of STING-interferon signaling by CD11b agonists enhances anti-tumor immunity.

Chronic activation of inflammatory pathways and suppressed interferon are hallmarks of immunosuppressive tumors. Previous studies have shown that CD11b integrin agonists could enhance anti-tumor immunity through myeloid reprograming, but the underlying mechanisms remain unclear. Herein we find that CD11b agonists alter tumor-associated macrophage (TAM) phenotypes by repressing NF-κB signaling and activating interferon gene expression simultaneously. Repression of NF-κB signaling involves degradation of p65 protein and is context independent. In contrast, CD11b agonism induces STING/STAT1 pathway-mediated interferon gene expression through FAK-mediated mitochondrial dysfunction, with the magnitude of induction dependent on the tumor microenvironment and amplified by cytotoxic therapies. Using tissues from phase I clinical studies, we demonstrate that GB1275 treatment activates STING and STAT1 signaling in TAMs in human tumors. These findings suggest potential mechanism-based therapeutic strategies for CD11b agonists and identify patient populations more likely to benefit.

Cytotoxic CD161-CD8+ TEMRA cells contribute to the pathogenesis of systemic lupus erythematosus.

BACKGROUND: Systemic lupus erythematosus (SLE) is a prototypical autoimmune disease affecting multiple organs and tissues with high cellular heterogeneity. CD8+ T cell activity is involved in the SLE pathogenesis. However, the cellular heterogeneity and the underlying mechanisms of CD8+ T cells in SLE remain to be identified. METHODS: Single-cell RNA sequencing (scRNA-seq) of PBMCs from a SLE family pedigree (including 3 HCs and 2 SLE patients) was performed to identify the SLE-associated CD8+ T cell subsets. Flow cytometry analysis of a SLE cohort (including 23 HCs and 33 SLE patients), qPCR analysis of another SLE cohort (including 30 HCs and 25 SLE patients) and public scRNA-seq datasets of autoimmune diseases were employed to validate the finding. Whole-exome sequencing (WES) of this SLE family pedigree was used to investigate the genetic basis in dysregulation of CD8+ T cell subsets identified in this study. Co-culture experiments were performed to analyze the activity of CD8+ T cells. FINDINGS: We elucidated the cellular heterogeneity of SLE and identified a new highly cytotoxic CD8+ T cell subset, CD161-CD8+ TEMRA cell subpopulation, which was remarkably increased in SLE patients. Meanwhile, we discovered a close correlation between mutation of DTHD1 and the abnormal accumulation of CD161-CD8+ TEMRA cells in SLE. DTHD1 interacted with MYD88 to suppress its activity in T cells and DTHD1 mutation promoted MYD88-dependent pathway and subsequently increased the proliferation and cytotoxicity of CD161-CD8+ TEMRA cells. Furthermore, the differentially expressed genes in CD161-CD8+ TEMRA cells displayed a strong out-of-sample prediction for case-control status of SLE. INTERPRETATION: This study identified DTHD1-associated expansion of CD161-CD8+ TEMRA cell subpopulation is critical for SLE. Our study highlights genetic association and cellular heterogeneity of SLE pathogenesis and provides a mechanistical insight into the diagnosis and treatment of SLE. FUNDINGS: Stated in the Acknowledgements section of the manuscript.

Stromal and therapy-induced macrophage proliferation promotes PDAC progression and susceptibility to innate immunotherapy.

Tumor-associated macrophages (TAMs) are abundant in pancreatic ductal adenocarcinomas (PDACs). While TAMs are known to proliferate in cancer tissues, the impact of this on macrophage phenotype and disease progression is poorly understood. We showed that in PDAC, proliferation of TAMs could be driven by colony stimulating factor-1 (CSF1) produced by cancer-associated fibroblasts. CSF1 induced high levels of p21 in macrophages, which regulated both TAM proliferation and phenotype. TAMs in human and mouse PDACs with high levels of p21 had more inflammatory and immunosuppressive phenotypes. p21 expression in TAMs was induced by both stromal interaction and/or chemotherapy treatment. Finally, by modeling p21 expression levels in TAMs, we found that p21-driven macrophage immunosuppression in vivo drove tumor progression. Serendipitously, the same p21-driven pathways that drive tumor progression also drove response to CD40 agonist. These data suggest that stromal or therapy-induced regulation of cell cycle machinery can regulate both macrophage-mediated immune suppression and susceptibility to innate immunotherapy.

CD19+CD24highCD27+ B cell and interleukin 35 as potential biomarkers of disease activity in systemic lupus erythematosus patients.

BACKGROUND: Systemic lupus erythematosus (SLE) is a systemic autoimmune disease that associates with aberrant activation of B lymphocytes and excessive autoantibodies. Interleukin 10 (IL-10)/interleukin 35 (IL-35) and IL-10/IL-35-producing regulatory B cells have been demonstrated to possess immunosuppressive functions during systemic lupus erythematosus. Here, we detected the proportion of CD19+CD24highCD27+ B cells as well as IL-10 and IL-35 levels in peripheral blood of SLE patients and healthy individuals, and investigated their relations with clinical features of SLE. METHODS: 41 SLE patients and 25 healthy controls were recruited. The patients were divided into groups based on SLEDAI score, anti-dsDNA antibody, rash, nephritis and hematological disorder. Flow cytometry was used to detect the proportion of CD24hiCD27+ B cells. ELISA was used to detect serum levels of IL-10 and IL-35. RESULTS: Our results showed that the CD19+CD24highCD27+ B population was decreased in active SLE patients, and anti-correlated with the disease activity. Of note, we found significant increase of IL-10 and decrease of IL-35 in SLE patients with disease activity score > 4, lupus nephritis or hematological disorders compared to those without related clinical features. CONCLUSIONS: Reduced CD19+CD24highCD27+ B cells expression may be involved in the pathogenesis of SLE. Moreover, we supposed that IL-35 instead of IL-10 played a crucial role in immune regulation during SLE disease.

Stromal Reprogramming by FAK Inhibition Overcomes Radiation Resistance to Allow for Immune Priming and Response to Checkpoint Blockade.

The effects of radiotherapy (RT) on tumor immunity in pancreatic ductal adenocarcinoma (PDAC) are not well understood. To better understand if RT can prime antigen-specific T-cell responses, we analyzed human PDAC tissues and mouse models. In both settings, there was little evidence of RT-induced T-cell priming. Using in vitro systems, we found that tumor-stromal components, including fibroblasts and collagen, cooperate to blunt RT efficacy and impair RT-induced interferon signaling. Focal adhesion kinase (FAK) inhibition rescued RT efficacy in vitro and in vivo, leading to tumor regression, T-cell priming, and enhanced long-term survival in PDAC mouse models. Based on these data, we initiated a clinical trial of defactinib in combination with stereotactic body RT in patients with PDAC (NCT04331041). Analysis of PDAC tissues from these patients showed stromal reprogramming mirroring our findings in genetically engineered mouse models. Finally, the addition of checkpoint immunotherapy to RT and FAK inhibition in animal models led to complete tumor regression and long-term survival. SIGNIFICANCE: Checkpoint immunotherapeutics have not been effective in PDAC, even when combined with RT. One possible explanation is that RT fails to prime T-cell responses in PDAC. Here, we show that FAK inhibition allows RT to prime tumor immunity and unlock responsiveness to checkpoint immunotherapy. This article is highlighted in the In This Issue feature, p. 2711.

Profiling Serum Cytokines and Anticytokine Antibodies in Psoriasis Patients.

Cytokines like IL-17A have been consistently found to be elevated in psoriatic lesional skin, and therapeutic antibodies to IL-17 have demonstrated efficacy in treating psoriatic skin and joint disease. However, results about the circulating cytokines in psoriasis patients remained controversial. Anticytokine autoantibodies (ACAAs) were detected in various autoimmune diseases but remained largely unknown in psoriasis. We aimed to investigate the serum levels of cytokines and ACAAs in psoriasis patients. The study included 44 biologics-naive psoriasis patients and 40 healthy controls. Serum cytokines and the corresponding autoantibodies were measured by multiplex bead-based technology. The bioactivity of serum IL-17A was determined by IL-8 production in primary keratinocytes. Herein, we found serum levels of IL-12B (median: 6.16 vs. 9.03, p = 0.0194) and Th17 cytokines (IL-17A: median: 0.32 vs. 1.05, p = 0.0026; IL-22: median: 4.41 vs. 4.41, p = 0.0120) were increased in psoriasis patients. More interestingly, bioactive IL-17A was identified in a proportion of patients and positively correlated with disease severity. A few of cytokines were closely associated with each other and formed into a distinct panel in psoriasis. Of 13 anticytokine antibodies, anti-IL-22 was moderately lower (median: 262.8 vs.190.5, p = 0.0418), and anti-IL-15 was slightly higher (median: 25.5 vs. 30.5, p = 0.0069) in psoriasis than controls. None of ACAAs was related to disease severity. Consequently, the ratios of antibodies to cytokines varied with the pattern of cytokines. In summary, our finding suggested that the levels of circulating bioactive IL-17A were associated with disease activity in psoriasis patients. In contrast, the titers of ACAAs were not significantly altered nor correlated with disease severity. However, the functionality of ACAAs remains to be further demonstrated in vitro in future studies.

Etanercept treatment of Stevens-Johnson syndrome and toxic epidermal necrolysis.

BACKGROUND: Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) is a severe cutaneous adverse reaction to drugs with considerable morbidity and mortality. Immunomodulators for SJS/TEN including systemic corticosteroids and intravenous immunoglobulin (IVIG) have been widely used in clinical practice. Emerging evidence suggested the therapeutic effects of tumor necrosis factor-α antagonists on SJS/TEN. OBJECTIVE: To compare the efficacy and safety of IVIG and systemic steroids in conjunction with or without etanercept, a tumor necrosis factor-α inhibitor, for patients with SJS/TEN. METHODS: We undertook a retrospective review of 41 patients with SJS/TEN admitted to our institution from 2015 to February 2021. A total of 25 patients with integrated data were involved in this study, of which 14 patients were treated with IVIG and corticosteroids and 11 were in addition given etanercept. The clinical characteristics, duration of hospitalization, exposure time to high-dose steroids, and the total amount of systemic steroids were analyzed. RESULTS: In comparison to conventional therapy, conjunction with etanercept reduced the duration of hospitalization (13.5 vs 19.0 days; P = .01), the exposure time of high-dose steroids (7.1 vs 14.9 days; P = .01), and the overall amount of systemic steroid (925 mg vs 1412.5 mg; P = .03) in patients with SJS/TEN. No pronounced adverse effects were observed within 6 months of follow-up after the treatment. CONCLUSION: The add-in of etanercept at the time of initiating conventional therapy could be a superior option to accelerate disease recovery and reduce the high dose and total amount of systemic steroids without pronounced adverse events in patients with SJS/TEN.

Enhanced Migratory Ability of Neutrophils Toward Epidermis Contributes to the Development of Psoriasis via Crosstalk With Keratinocytes by Releasing IL-17A.

Microabscess of neutrophils in epidermis is one of the histological hallmarks of psoriasis. The axis of neutrophil-keratinocyte has been thought to play a critical role in the pathogenesis of psoriasis. However, the features and mechanism of interaction between the two cell types remain largely unknown. Herein, we found that blood neutrophils were increased in psoriasis patients, positively correlated with disease severity and highly expressed CD66b, but not CD11b and CD62L compared to healthy controls. Keratinocytes expressed high levels of psoriasis-related inflammatory mediators by direct and indirect interaction with neutrophils isolated from psoriasis patients and healthy controls. The capacity of neutrophils in provoking keratinocytes inflammatory response was comparable between the two groups and is dependent on IL-17A produced by itself. Neutrophils isolated from psoriasis patients displayed more transcriptome changes related to integrin and increased migration capacity toward keratinocytes with high CD11b expression on cell surface. Of interest, neutrophils were more susceptible to keratinocyte stimulation than to fibroblasts and human umbilical vein endothelial cells (HUVECs) in terms of CD11b expression and the production of ROS and NETs. In conclusion, neutrophils from psoriasis patients gain a strong capacity of IL-17A production and integrins expression that possibly facilitates their abilities to promote production of psoriasis-related inflammatory mediators and migration, a phenomenon likely induced by their interaction with keratinocytes but not with fibroblasts. These findings provide a proof-of-concept that development of new drugs targeting migration of neutrophils could be a more specific and safe solution to treat psoriasis.

IRAK4 Signaling Drives Resistance to Checkpoint Immunotherapy in Pancreatic Ductal Adenocarcinoma.

BACKGROUND & AIMS: Checkpoint immunotherapy is largely ineffective in pancreatic ductal adenocarcinoma (PDAC). The innate immune nuclear factor (NF)-κB pathway promotes PDAC cell survival and stromal fibrosis, and is driven by Interleukin-1 Receptor Associated Kinase-4 (IRAK4), but its impact on tumor immunity has not been directly investigated. METHODS: We interrogated The Cancer Genome Atlas data to identify the correlation between NF-κB and T cell signature, and a PDAC tissue microarray (TMA) to correlate IRAK4 activity with CD8+ T cell abundance. We performed RNA sequencing (RNA-seq) on IRAK4-deleted PDAC cells, and single-cell RNA-seq on autochthonous KPC (p48-Cre/TP53f/f/LSL-KRASG12D) mice treated with an IRAK4 inhibitor. We generated conditional IRAK4-deleted KPC mice and complementarily used IRAK4 inhibitors to determine the impact of IRAK4 on T cell immunity. RESULTS: We found positive correlation between NF-κB activity, IRAK4 and T cell exhaustion from The Cancer Genome Atlas. We observed inverse correlation between phosphorylated IRAK4 and CD8+ T cell abundance in a PDAC tissue microarray. Loss of IRAK4 abrogates NF-κB activity, several immunosuppressive factors, checkpoint ligands, and hyaluronan synthase 2, all of which drive T cell dysfunction. Accordingly, conditional deletion or pharmacologic inhibition of IRAK4 markedly decreased tumor desmoplasia and increased the abundance and activity of infiltrative CD4+ and CD8+ T cells in KPC tumors. Single-cell RNA-seq showed myeloid and fibroblast reprogramming toward acute inflammatory responses following IRAK4 inhibition. These changes set the stage for successful combination of IRAK4 inhibitors with checkpoint immunotherapy, resulting in excellent tumor control and markedly prolonged survival of KPC mice. CONCLUSION: IRAK4 drives T cell dysfunction in PDAC and is a novel, promising immunotherapeutic target.

ULK1 Inhibition as a Targeted Therapeutic Strategy for Psoriasis by Regulating Keratinocytes and Their Crosstalk With Neutrophils.

Psoriasis is a common inflammatory skin disease resulting from an interplay of keratinocytes and immune cells. Previous studies have identified an essential role of autophagy in the maintenance of epidermal homeostasis including proliferation and differentiation. However, much less is known about the role of autophagy-related proteins in the cutaneous immune response. Herein, we showed that ULK1, the key autophagic initiator, and its phosphorylation at Ser556 were distinctively decreased in the epidermis from lesional skin of psoriasis patients. Topical application of SBI0206965, a selective ULK1 inhibitor, significantly attenuated epidermal hyperplasia, infiltration of neutrophils, and transcripts of the psoriasis-related markers in imiquimod (IMQ)-induced psoriasiform dermatitis (PsD). In vitro, ULK1 impairment by siRNA and SBI0206965 arrested cell proliferation and promoted apoptosis of keratinocytes but had a marginal effect on the expression of proinflammatory mediators under steady status. Surprisingly, SBI0206965 blocked the production of chemokines and cytokines in keratinocytes stimulated by neutrophils. Of interest, the pro-apoptotic and anti-inflammatory effects of ULK1 inhibition cannot be fully replicated by autophagic inhibitors. Our findings suggest a self-regulatory process by downregulating ULK1 to maintain the immune homeostasis of psoriatic skin via regulating keratinocytes and their crosstalk with neutrophils, possibly through both autophagy-dependent and independent mechanisms. ULK1 might be a potential target for preventing or treating psoriasis.

Comparison of Digestive Enzyme Activities and Expression of Small Intestinal Transporter Genes in Jinhua and Landrace Pigs.

Digestive enzyme activity is involved in the regulation of growth performance because digestive enzymes function to improve the feed efficiency by digestion and in turn to modulate the process of nutrient metabolism. The objective of this study was to investigate the differences of the digestive enzyme activities and expression of nutrient transporters in the intestinal tract between Jinhua and Landrace pigs and to explore the potential breed-specificity in digestion and absorption. The pancreas segments and the digesta and mucosa of the duodenum, jejunum, and ileum were collected from 10 Jinhua pigs and Landrace pigs, respectively. The activities of trypsin, chymotrypsin, amylase, maltase, sucrase, and lipase were measured and the expression levels of PepT1, GLUT2, SGLT1, FABP1, FABP2, and FABP4 were examined. Results showed that the trypsin activity in the pancreas of Jinhua pigs was higher than that in Landrace pigs, but was lower in the small intestine, except for in the jejunal mucosa. The chymotrypsin activity in the small intestine of Jinhua pigs was higher than that in Landrace pigs, except for in jejunal mucosa and contents. Compared with Landrace pigs, the amylase and maltase activity in the small intestine of Jinhua pigs was lower, except for in ileal mucosa. The sucrase activity in the small intestine of Jinhua pigs was also lower than Landrace pigs, except for in jejunal mucosa. Furthermore, the lipase activity in the small intestine of Jinhua pigs was higher than that in Landrace pigs. The mRNA levels of PepT1 and GLUT2 in duodenal, jejunal and ileal mucosa showed no difference between Jinhua and Landrace pigs, whereas SGLT1 in ileal mucosa was lower in Jinhua pigs. The mRNA levels of FABP1, FABP2 and FABP4 in the small intestinal mucosa of Jinhua pigs were higher than in Landrace pigs. These findings indicate that there is a certain difference in the digestibility and absorption of nutrients in small intestine of Jinhua and Landrace pigs, partially resulting in their differences in growth development and fat deposition.

Blockade of IDO-Kynurenine-AhR Axis Ameliorated Colitis-Associated Colon Cancer via Inhibiting Immune Tolerance.

BACKGROUND & AIMS: Chronic inflammation in colon section is associated with an increased risk of colorectal cancer (CRC). Proinflammatory cytokines were produced in a tumor microenvironment and correlated with poor clinical outcome. Tumor-infiltrating T cells were reported to be greatly involved in the development of colon cancer. In this study, we demonstrated that kynurenine (Kyn), a metabolite catalyzed by indoleamine 2,3-dioxygenase (IDO), was required for IDO-mediated T cell function, and adaptive immunity indeed played a critical role in CRC. METHODS: Supernatant of colon cancer cells was used to culture activated T cells and mice spleen lymphocytes, and the IDO1-Kyn-aryl hydrocarbon (AhR) receptor axis was determined in vitro. In vivo, an azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced CRC model was established in IDO-/-, Rag1-/-, and wild-type mice, and tumor-associated T lymphocyte infiltration and Kyn/AhR signaling pathway changes were measured in each group. RESULTS: Kyn promoted AhR nuclear translocation increased the transcription of Foxp3, a marker of regulatory T cells (Tregs), through improving the interaction between AhR and Foxp3 promoter. Additionally, compared WT mice, IDO-/- mice treated with AOM/DSS exhibited fewer and smaller tumor burdens in the colon, with less Treg and more CD8+ T cells infiltration, while Kyn administration abolished this regulation. Rag1-/- mice were more sensitive to AOM/DSS-induced colitis-associated colon cancer (CRC) compared with the wild-type mice, suggesting that T cell-mediated adaptive immunity indeed played a critical role in CRC. CONCLUSIONS: We demonstrated that inhibition of IDO diminished Kyn/AhR-mediated Treg differentiation and could be an effective strategy for the prevention and treatment of inflammation-related colon cancer.

Transcriptome Analysis Reveals the Genes Involved in Growth and Metabolism in Muscovy Ducks.

Muscovy ducks are among the best meat ducks in the world. The objective of this study was to identify genes related to growth metabolism through transcriptome analysis of the ileal tissue of Muscovy ducks. Duck ileum samples with the highest (H group, n = 5) and lowest (L group, n = 5) body weight were selected from two hundred 70-day-old Muscovy ducks for transcriptome analysis by RNA sequencing. In the screening of differentially expressed genes (DEGs) between the H and L groups, a total of 602 DEGs with a fold change no less than 2 were identified, among which 285 were upregulated and 317 were downregulated. Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that glutathione metabolism, pyrimidine metabolism, and protein digestion and absorption processes played a vital role in regulating growth and metabolism. The results showed that 7 genes related to growth and metabolism, namely, ANPEP, ENPEP, UPP1, SLC2A2, SLC6A19, NME4, and LOC106034733, were significantly expressed in group H, which was consistent with the phenotype results. The validation of these 7 genes using real-time quantitative PCR results indicated that the expression level of ENPEP was significantly different between the H and L groups (P < 0.05). This study provides a theoretical basis for exploring the influence of the ileum on growth and metabolism in ducks.

Cecal Microbiota Modulates Fat Deposition in Muscovy Ducks.

Ducks with the same genetic background vary greatly in their adiposity phenotypes. The gut microbiota plays an essential role in host physiological development and metabolism including fat deposition. However, the association of the gut microbiota with the lipogenic phenotype of ducks remains unknown. In this study, we investigated the cecal microbiota of adult Muscovy ducks and the correlation of the cecal microbiota with fat phenotypes. A total of 200 Muscovy ducks were selected from a population of 5,000 Muscovy ducks to record their abdominal fat weight and collect their cecal contents after being slaughtered and defeathered. The cecal contents were subjective to DNA isolation and 16S rRNA gene sequencing. The results were sorted according to the percentage of abdominal fat and the top 20% (n = 40) and the bottom 20% (n = 40) were set as the high and low groups, respectively. Our results indicated that in the cecum of Muscovy ducks, Bacteroidetes, Firmicutes, and Fusobacteria were the predominant phyla while Bacteroides, Oscillospiraceae_uncultured, Parabacteroides, and Bacteroidales_norank were the top 4 dominant genera. Abdominal fat weight (18.57~138.10 g) and percentage of abdominal fat (1.02~27.12%) were significantly correlated (R 2 = 0.92, P < 0.001). Although the lipogenic phenotypes of ducks had a significant difference (P < 0.05), the α-diversities of the high and low groups were not significantly different (P > 0.05). Nevertheless, after random forest analysis, we identified two genera, Treponema and Ruminococcus_torques_group, that were significantly associated with fat deposition in Muscovy ducks. In addition, the abundances of Treponema and Ruminococcus_torques_group gave a significantly negative and positive association with abdominal fat weight, respectively (P < 0.05). Ducks with a low level of Treponema exhibited a tendency toward a high percentage of abdominal fat (P < 0.01), while the percentage of abdominal fat in ducks with high Ruminococcus_torques_group abundance tended to be higher than that in ducks with low Ruminococcus_torques_group abundance (P < 0.01). These findings could provide the basic data on the cecal microbiota in Muscovy ducks as well as a theoretical foundation to limit the fat deposition by modulating the gut microbiota in the duck industry.