技术资料

Experimental autoimmune uveoretinitis (EAU) is a mouse model of human autoimmune uveitis marked by ocular autoantigen-specific regulatory immunity in the spleen. The melanocortin 5 receptor (MC5r) and adenosine 2 A receptor (A2Ar) are required for induction of post-EAU regulatory T cells (Tregs) which provide resistance to EAU. We show that blocking the PD-1/PD-L1 pathway prevented suppression of EAU by post-EAU Tregs. A2Ar induction of PD-1+FoxP3+ Tregs in uveitis patients was similar compared to healthy controls,but was significantly reduced with melanocortin stimulation. Further,lower body mass index correlated with responsiveness to stimulation of this pathway. These observations indicate an importance of the PD-1/PD-L1 pathway to provide resistance to relapsing uveitis and shows a reduced capacity of uveitis patients to induce Tregs when stimulated through melanocortin receptors,but that it is possible to bypass this part of the pathway through direct stimulation of A2Ar. View Publication

Aim Reactive oxygen species (ROS) produced by enzymes of the NADPH oxidase family serve as second messengers for cellular signaling. Processes such as differentiation and proliferation are regulated by NADPH oxidases. In the intestine,due to the exceedingly fast and constant renewal of the epithelium both processes have to be highly controlled and balanced. Nox1 is the major NADPH oxidase expressed in the gut,and its function is regulated by cytosolic subunits such as NoxO1. We hypothesize that the NoxO1-controlled activity of Nox1 contributes to a proper epithelial homeostasis and renewal in the gut. Results NoxO1 is highly expressed in the colon. Knockout of NoxO1 reduces the production of superoxide in colon crypts and is not subsidized by an elevated expression of its homolog p47phox. Knockout of NoxO1 increases the proliferative capacity and prevents apoptosis of colon epithelial cells. In mouse models of dextran sulfate sodium (DSS)-induced colitis and azoxymethane/DSS induced colon cancer,NoxO1 has a protective role and may influence the population of natural killer cells. Conclusion NoxO1 affects colon epithelium homeostasis and prevents inflammation. View Publication

Tissue-resident memory CD8+ T (Trm) cells mediate potent local innate and adaptive immune responses and play a central role against solid tumors. However,whether Trm cells cross-talk with dendritic cells (DCs) to support anti-tumor immunity remains unclear. Here we show that antigen-specific activation of skin Trm cells leads to maturation and migration to draining lymph nodes of cross-presenting dermal DCs. Tumor rejection mediated by Trm cells triggers the spread of cytotoxic CD8+ T cell responses against tumor-derived neo- and self-antigens via dermal DCs. These responses suppress the growth of intradermal tumors and disseminated melanoma lacking the Trm cell-targeted epitope. Moreover,analysis of RNA sequencing data from human melanoma tumors reveals that enrichment of a Trm cell gene signature associates with DC activation and improved survival. This work unveils the ability of Trm cells to amplify the breath of cytotoxic CD8+ T cell responses through DCs,thereby strengthening anti-tumor immunity. View Publication

Gastrointestinal dysfunction in cystic fibrosis (CF) is a prominent source of pain among patients with CF. Linaclotide,a guanylate cyclase C (GCC) receptor agonist,is a US Food and Drug Administration-approved drug prescribed for chronic constipation but has not been widely used in CF,as the cystic fibrosis transmembrane conductance regulator (CFTR) is the main mechanism of action. However,anecdotal clinical evidence suggests that linaclotide may be effective for treating some gastrointestinal symptoms in CF. The goal of this study was to determine the effectiveness and mechanism of linaclotide in treating CF gastrointestinal disorders using CF mouse models. Intestinal transit,chloride secretion,and intestinal lumen fluidity were assessed in wild-type and CF mouse models in response to linaclotide. CFTR and sodium/hydrogen exchanger 3 (NHE3) response to linaclotide was also evaluated. Linaclotide treatment improved intestinal transit in mice carrying either F508del or null Cftr mutations but did not induce detectable Cl- secretion. Linaclotide increased fluid retention and fluidity of CF intestinal contents,suggesting inhibition of fluid absorption. Targeted inhibition of sodium absorption by the NHE3 inhibitor tenapanor produced improvements in gastrointestinal transit similar to those produced by linaclotide treatment,suggesting that inhibition of fluid absorption by linaclotide contributes to improved gastrointestinal transit in CF. Our results demonstrate that linaclotide improves gastrointestinal transit in CF mouse models by increasing luminal fluidity through inhibiting NHE3-mediated sodium absorption. Further studies are necessary to assess whether linaclotide could improve CF intestinal pathologies in patients. GCC signaling and NHE3 inhibition may be therapeutic targets for CF intestinal manifestations. NEW {\&} NOTEWORTHY Linaclotide's primary mechanism of action in alleviating chronic constipation is through cystic fibrosis transmembrane conductance regulator (CFTR),negating its use in patients with cystic fibrosis (CF). For the first time,our findings suggest that in the absence of CFTR,linaclotide can improve fluidity of the intestinal lumen through the inhibition of sodium/hydrogen exchanger 3. These findings suggest that linaclotide could improve CF intestinal pathologies in patients. View Publication

Secreted factors derived from Lactobacillus are able to dampen pro-inflammatory cytokine responses. Still,the nature of these components and the underlying mechanisms remain elusive. Here,we aimed to identify the components and the mechanism involved in the Lactobacillus-mediated modulation of immune cell activation. PBMC were stimulated in the presence of the cell free supernatants (CFS) of cultured Lactobacillus rhamnosus GG and Lactobacillus reuteri DSM 17938,followed by evaluation of cytokine responses. We show that lactobacilli-CFS effectively dampen induced IFN-$\gamma$ and IL-17A responses from T- and NK cells in a monocyte dependent manner by a soluble factor. A proteomic array analysis highlighted Lactobacillus-induced IL-1 receptor antagonist (ra) as a potential candidate responsible for the IFN-$\gamma$ dampening activity. Indeed,addition of recombinant IL-1ra to stimulated PBMC resulted in reduced IFN-$\gamma$ production. Further characterization of the lactobacilli-CFS revealed the presence of extracellular membrane vesicles with a similar immune regulatory activity to that observed with the lactobacilli-CFS. In conclusion,we have shown that lactobacilli produce extracellular MVs,which are able to dampen pro-inflammatory cytokine responses in a monocyte-dependent manner. View Publication

Sustained,indolent immune injury of the vasculature of a heart transplant limits long-term graft and recipient survival. This injury is mitigated by a poorly characterized,maladaptive repair response. Vascular endothelial cells respond to proangiogenic cues in the embryo by differentiation to specialized phenotypes,associated with expression of apelin. In the adult,the role of developmental proangiogenic cues in repair of the established vasculature is largely unknown. We found that human and minor histocompatibility-mismatched donor mouse heart allografts with alloimmune-mediated vasculopathy upregulated expression of apelin in arteries and myocardial microvessels. In vivo,loss of donor heart expression of apelin facilitated graft immune cell infiltration,blunted vascular repair,and worsened occlusive vasculopathy in mice. In vitro,an apelin receptor agonist analog elicited endothelial nitric oxide synthase activation to promote endothelial monolayer wound repair and reduce immune cell adhesion. Thus,apelin acted as an autocrine growth cue to sustain vascular repair and mitigate the effects of immune injury. Treatment with an apelin receptor agonist after vasculopathy was established markedly reduced progression of arterial occlusion in mice. Together,these initial data identify proangiogenic apelin as a key mediator of coronary vascular repair and a pharmacotherapeutic target for immune-mediated injury of the coronary vasculature. View Publication

Peripheral serotonin (5-hydroxytryptamine: 5-HT) synthesized in the intestine by enterochromaffin cells (ECs),plays an important role in the regulation of peristaltic of the gut,epithelial secretion and promotes the development and maintenance of the enteric neurons. Recent studies showed that the indigenous gut microbiota modulates 5-HT signalling and that ECs use sensory receptors to detect dietary and microbiota-derived signals from the lumen to subsequently transduce the information to the nervous system. We hypothesized that Clostridium ramosum by increasing gut 5-HT availability consequently contributes to high-fat diet-induced obesity. Using germ-free mice and mice monoassociated with C. ramosum,intestinal cell lines and mouse organoids,we demonstrated that bacterial cell components stimulate host 5-HT secretion and program the differentiation of colonic intestinal stem progenitors toward the secretory 5-HT-producing lineage. An elevated 5-HT level regulates the expression of major proteins involved in intestinal fatty acid absorption in vitro,suggesting that the presence of C. ramosum in the gut promotes 5-HT secretion and thereby could facilitates intestinal lipid absorption and the development of obesity. View Publication

Apoptosis and autophagy are dynamic processes that determine the fate of cells. Vitamin D receptor (VDR) deficiency in the intestine leads to abnormal Paneth cells and impaired autophagy function. Here,we will elucidate the mechanisms of the intestinal epithelial VDR regulation of autophagy and apoptosis. We used in vivo VDRlox and VDR∆IEC mice and ex vivo organoids generated from small intestine and colon tissues. We found that VDR deficiency induced more apoptotic cells and significantly increased cell death in the small intestine and colon of VDR∆IEC mice. The proapoptotic protein B-cell lymphoma 2 (BCL-2) associated X protein (Bax) was enhanced,whereas autophagy related 16 like 1 (ATG16L1) and Beclin-1 were decreased in the intestines of VDR$\Delta$IEC mice. Apoptosis induced by Bax reduced autophagy by decreasing Beclin-1. Physical interactions between Beclin-1 and Bcl-2 were increased in the VDR-deficient epithelia from mice. The growth of VDR∆IEC organoids was significantly slower with fewer Paneth cells than that of VDR+/+ organoids. The expression levels of Beclin-1 and lysozyme were decreased in VDR∆IEC organoids. Bacterial endotoxin levels were high in the serum from VDR∆IEC mice and made mice susceptible to colitis. In the organoids and colitis IL-10-/- mice,vitamin D3 treatment increased VDR and ATG16L1 protein expression levels,which activated autophagic responses. In summary,intestinal epithelial VDR regulates autophagy and apoptosis through ATG16L1 and Beclin-1. Our studies provide fundamental insights into the tissue-specific function of VDR in modulating the balance between autophagy and apoptosis.-Lu,R.,Zhang,Y.-G.,Xia,Y.,Sun,J. Imbalance of autophagy and apoptosis in intestinal epithelium lacking the vitamin D receptor. View Publication

BACKGROUND MiR-199a-3p (miR-199a) can enhance the chemosensitivity of hepatocellular carcinoma (HCC). Because of the easy degradation of miRNA by direct infusion,effective vehicle-mediated delivery of miR-199a may represent a new strategy for improving HCC chemotherapy. Considering mesenchymal stem cell (MSC)-derived exosomes as promising natural nanovectors for drug and molecule delivery,we aimed to determine whether exosomes from adipose tissue-derived MSCs (AMSCs) could be used to deliver miR-199a and improve HCC chemosensitivity. METHODS MiR-199a-modified AMSCs (AMSC-199a) were constructed by miR-199a lentivirus infection and puromycin selection. MiR-199-modified exosomes (AMSC-Exo-199a) were isolated from the supernatant of AMSC-199a and were assessed by transmission electron microscopy,nanoparticle tracking analysis,and flow cytometry analysis. The expression levels of miR-199a in HCC samples,AMSCs,exosomes,and HCC cells were quantified by real-time PCR. The effects of AMSC-Exo-199a on HCC chemosensitivity were determined by cell proliferation and apoptosis assays and by i.v. injection into orthotopic HCC mouse models with doxorubicin treatment. MTOR,p-4EBP1 and p-70S6K levels in HCC cells and tissues were quantified by Western blot. RESULTS AMSC-Exo-199a had the classic characteristics of exosomes and could effectively mediate miR-199a delivery to HCC cells. Additionally,AMSC-Exo-199a significantly sensitized HCC cells to doxorubicin by targeting mTOR and subsequently inhibiting the mTOR pathway. Moreover,i.v.-injected AMSC-Exo-199a could distribute to tumor tissue and markedly increased the effect of Dox against HCC in vivo. CONCLUSIONS AMSC-Exo-199a can be an effective vehicle for miR-199a delivery,and they effectively sensitized HCC to chemotherapeutic agents by targeting mTOR pathway. AMSC-Exo-199a administration may provide a new strategy for improving HCC chemosensitivity. View Publication

The gut microbiome contributes to inflammatory bowel disease (IBD),in which bacteria can be present within the epithelium. Epithelial barrier function is decreased in IBD,and dysfunctional epithelial mitochondria and endoplasmic reticulum (ER) stress have been individually associated with IBD. We therefore hypothesized that the combination of ER and mitochondrial stresses significantly disrupt epithelial barrier function. Here,we treated human colonic biopsies,epithelial colonoids,and epithelial cells with an uncoupler of oxidative phosphorylation,dinitrophenol (DNP),with or without the ER stressor tunicamycin and assessed epithelial barrier function by monitoring internalization and translocation of commensal bacteria. We also examined barrier function and colitis in mice exposed to dextran sodium sulfate (DSS) or DNP and co-treated with DAPK6,an inhibitor of death-associated protein kinase 1 (DAPK1). Contrary to our hypothesis,induction of ER stress (i.e. the unfolded protein response) protected against decreased barrier function caused by the disruption of mitochondrial function. ER stress did not prevent DNP-driven uptake of bacteria; rather,specific mobilization of the ATF6 arm of ER stress and recruitment of DAPK1 resulted in enhanced autophagic killing (xenophagy) of bacteria. Of note,epithelia with a Crohn's disease-susceptibility mutation in the autophagy gene ATG16L1 exhibited less xenophagy. Systemic delivery of the DAPK1 inhibitor DAPK6 increased bacterial translocation in DSS- or DNP-treated mice. We conclude that promoting ER stress-ATF6-DAPK1 signaling in transporting enterocytes counters the transcellular passage of bacteria evoked by dysfunctional mitochondria,thereby reducing the potential for metabolic stress to reactivate or perpetuate inflammation. View Publication

Autoimmune diseases are a physiological state wherein immune responses are directed against and damage the body's own tissues. Cytokines secreted by infiltrated inflammatory cells contribute to the pathogenesis of autoimmune diseases. TIPE2,one of the four family members of Tumor necrosis factor-$\alpha$ induced protein-8 (TNFAIP8),is a negative regulator of innate and adaptive immunity and plays essential roles in the maintenance of immune tolerance. However,studies on the role of TIPE2 during the development of autoimmune diseases have generated contradictory results. In the current study,we sought to determine the role of TIPE2 during the development of IMQ-induced psoriasis and Experimental Autoimmune Uveitis (EAU) in mice. Our study revealed that,while TIPE2-deficiency alleviates psoriasis,it exacerbates the development of EAU. Further studies demonstrated that,although TIPE2-deficient T cells produced more IL-17A,they do not migrate efficiently to the local inflammatory site,i.e.,the skin. This in turn led to the decreased IL-17A production in the skin and consequently reduced the severity of psoriasis in TIPE2-deficient mice. However,although TIPE2-deficient T cells still produced more IL-17A in EAU model,they migrate into the inflamed eye as efficient as TIPE2-sufficient T cells,and consequently exacerbates the development of EAU in TIPE2-deficient mice. Taken together,these results indicate that TIPE2 may either promote or suppress autoimmunity depending on the specific inflammatory microenvironment in different types of autoimmune diseases. View Publication

Cytotoxic chemotherapies could cause the dysregulation of hematopoiesis and even put patients at increased risk of hematopoietic malignancy. Therapy-related leukemia is mainly caused by cytotoxic chemotherapy-induced genetic mutations in hematopoietic stem/progenitor cells (HSPCs). In addition to the intrinsic mechanism,some extrinsic events occurring in the bone marrow (BM) microenvironment are also possible mechanisms involved in genetic alteration. In the present study,we investigated the damage to BM stromal cells induced by a chemotherapy drug,daunorubicin (DNR) and further identified the DNA damage in hematopoietic cells caused by drug-treated stromal cells. It was found that treatment with DNR in mice caused a temporary reduction in cell number in each BM stromal cell subpopulation and the impairment of clonal growth potential in BM stromal cells. DNR treatment led to a tendency of senescence,generation of intracellular reactive oxygen species,production of cytokines and chemokines,and dysfunction of mitochondrial in stromal cells. Transcriptome microarray data and gene ontology (GO) or gene set enrichment analysis (GSEA) showed that differentially expressed genes that were down-regulated in response to DNR treatment were significantly enriched in mitochondrion function,and negative regulators of reactive oxygen species. Surprisingly,it was found that DNR-treated stromal cells secreted high levels of H2O2 into the culture supernatant. Furthermore,coculture of hematopoietic cells with DNR-treated stromal cells led to the accumulation of DNA damage as determined by the levels of histone H2AX phosphorylation and 8-oxo-2'-deoxyguanosine in hematopoietic cells. Overall,our results suggest that DNR-induced BM stromal cell damage can lead to genomic instability in hematopoietic cells. View Publication