Scientific Resources

Helminthic infections modulate host immunity and may protect their hosts from developing immunological diseases like inflammatory bowel disease. Induction of regulatory T cells (Tregs) may be an important part of this protective process. Heligmosomoides polygyrus bakeri infection also promotes the production of the regulatory cytokines TGF-beta and IL-10 in the gut. In the intestines,TGF-beta helps induce regulatory T cells. This study used Foxp3/IL-10 double reporter mice to investigate the effect of TGF-beta on the differentiation of colon and mesenteric lymph node-derived murine Foxp3- IL-10- CD4+ T cells into their regulatory phenotypes. Foxp3- IL-10- CD4+ T cells from H. polygyrus bakeri-infected mice,as opposed to T cells from uninfected animals,cultured in vitro with TGF-beta and anti-CD3/CD28 mAb differentiated into Foxp3+ and/or IL-10+ T cells. The IL-10-producing T cells nearly all displayed CD25. Smad7 is a natural inhibitor of TGF-beta signaling. In contrast to gut T cells from uninfected mice,Foxp3- IL10- CD4+ T cells from H. polygyrus bakeri-infected mice displayed reduced Smad7 expression and responded to TGF-beta with Smad2/3 phosphorylation. The TGF-beta-induced Tregs that express IL-10 blocked colitis when transferred into the Rag/CD25- CD4+ T cell transfer model of inflammatory bowel disease. TGF-beta had a greatly diminished capacity to induce Tregs in H. polygyrus bakeri-infected transgenic mice with constitutively high T cell-specific Smad7 expression. Thus,infection with H. polygyrus bakeri causes down-modulation in Smad7 expression in intestinal CD4+ T cells,which allows the TGF-beta produced in response to the infection to induce the Tregs that prevent colitis. View Publication

Emerging evidence suggests an immunosuppressive role of altered tumor glycosylation due to downregulation of innate immune responses via immunoregulatory Siglecs. In contrast,human T cells,a major anticancer effector cell,only rarely express Siglecs. However,here,we report that the majority of intratumoral,but not peripheral blood,cytotoxic CD8+ T cells expressed Siglec-9 in melanoma. We identified Siglec-9+ CD8+ T cells as a subset of effector memory cells with high functional capacity and signatures of clonal expansion. This cytotoxic T-cell subset was functionally inhibited in the presence of Siglec-9 ligands or by Siglec-9 engagement by specific antibodies. TCR signaling pathways and key effector functions (cytotoxicity,cytokine production) of CD8+ T cells were suppressed by Siglec-9 engagement,which was associated with the phosphorylation of the inhibitory protein tyrosine phosphatase SHP-1,but not SHP-2. Expression of cognate Siglec-9 ligands was observed on the majority of tumor cells in primary and metastatic melanoma specimens. Targeting the tumor-restricted,glycosylation-dependent Siglec-9 axis may unleash this intratumoral T-cell subset,while confining T-cell activation to the tumor microenvironment. View Publication

Clonal expansion of B cell chronic lymphocytic leukemia (B-CLL) occurs within lymphoid tissue pseudofollicles. IL-15,a stromal cell-associated cytokine found within spleens and lymph nodes of B-CLL patients,significantly boosts in vitro cycling of blood-derived B-CLL cells following CpG DNA priming. Both IL-15 and CpG DNA are elevated in microbe-draining lymphatic tissues,and unraveling the basis for IL-15-driven B-CLL growth could illuminate new therapeutic targets. Using CpG DNA-primed human B-CLL clones and approaches involving both immunofluorescent staining and pharmacologic inhibitors,we show that both PI3K/AKT and JAK/STAT5 pathways are activated and functionally important for IL-15→CD122/ɣc signaling in ODN-primed cells expressing activated pSTAT3. Furthermore,STAT5 activity must be sustained for continued cycling of CFSE-labeled B-CLL cells. Quantitative RT-PCR experiments with inhibitors of PI3K and STAT5 show that both contribute to IL-15-driven upregulation of mRNA for cyclin D2 and suppression of mRNA for DNA damage response mediators ATM,53BP1,and MDC1. Furthermore,protein levels of these DNA damage response molecules are reduced by IL-15,as indicated by Western blotting and immunofluorescent staining. Bioinformatics analysis of ENCODE chromatin immunoprecipitation sequencing data from cell lines provides insight into possible mechanisms for STAT5-mediated repression. Finally,pharmacologic inhibitors of JAKs and STAT5 significantly curtailed B-CLL cycling when added either early or late in a growth response. We discuss how the IL-15-induced changes in gene expression lead to rapid cycling and possibly enhanced mutagenesis. STAT5 inhibitors might be an effective modality for blocking B-CLL growth in patients. View Publication

The types and magnitude of Ag-specific immune responses can be determined by the functional plasticity of dendritic cells (DCs). However,how DCs display functional plasticity and control host immune responses have not been fully understood. In this study,we report that ligation of DC-asialoglycoprotein receptor (DC-ASGPR),a C-type lectin receptor (CLR) expressed on human DCs,resulted in rapid activation of Syk,followed by PLCgamma2 and PKCdelta engagements. However,different from other Syk-coupled CLRs,including Dectin-1,signaling cascade through DC-ASGPR did not trigger NF-kappaB activation. Instead,it selectively activated MAPK ERK1/2 and JNK. Rapid and prolonged phosphorylation of ERK1/2 led to sequential activation of p90RSK and CREB,which consequently bound to IL10 promoter and initiated cytokine expression. In addition,DC-ASGPR ligation activated Akt,which differentially regulated the activities of GSK-3alpha/beta and beta-catenin and further contributed to IL-10 expression. Our observations demonstrate that DC-ASGPR induces IL-10 expression via an intrinsic signaling pathway,which provides a molecular explanation for DC-ASGPR-mediated programing of DCs to control host immune responses. View Publication

The cancer stem cell (CSC) model suggests that a subpopulation of cells within the tumor,the CSCs,is responsible for cancer relapse and metastasis formation. CSCs hold unique characteristics,such as self-renewal,differentiation abilities,and resistance to chemotherapy,raising the need for discovering drugs that target CSCs. Previously we have found that the antihypertensive drug spironolactone impairs DNA damage response in cancer cells. Here we show that spironolactone,apart from inhibiting cancerous cell growth,is also highly toxic to CSCs. Notably,we demonstrate that CSCs have high basal levels of DNA double-strand breaks (DSBs). Mechanistically,we reveal that spironolactone does not damage the DNA but impairs DSB repair and induces apoptosis in cancer cells and CSCs while sparing healthy cells. In vivo,spironolactone treatment reduced the size and CSC content of tumors. Overall,we suggest spironolactone as an anticancer reagent,toxic to both cancer cells and,particularly to,CSCs. View Publication

The hexamethylene bisacetamide (HMBA) anticancer drug was dismissed due to limited efficacy in leukemic patients but it may re-enter into the clinics in HIV-1 eradication strategies because of its recently disclosed capacity to reactivate latent virus. Here,we investigated the impact of HMBA on the cytotoxicity of natural killer (NK) cells against acute T lymphoblastic leukemia (T-ALL) cells or HIV-1-infected T cells that exit from latency. We show that in T-ALL cells HMBA upmodulated MICB and ULBP2 ligands for the NKG2D activating receptor. In a primary CD4+ T cell-based latency model,HMBA did not reactivate HIV-1,yet enhanced ULBP2 expression on cells harboring virus reactivated by prostratin (PRO). However,HMBA reduced the expression of NKG2D and its DAP10 adaptor in NK cells,hence impairing NKG2D-mediated cytotoxicity and DAP10-dependent response to IL-15 stimulation. Alongside,HMBA dampened killing of T-ALL targets by IL-15-activated NK cells and impaired NK cell-mediated clearance of PRO-reactivated HIV-1+ cells. Overall,our results demonstrate a dominant detrimental effect of HMBA on the NKG2D pathway that crucially controls NK cell-mediated killing of tumors and virus-infected cells,providing one possible explanation for poor clinical outcome in HMBA-treated cancer patients and raising concerns for future therapeutic application of this drug. View Publication

Lentiviral vectors are the method of choice for stable gene modification of a variety of cell types. However,the efficiency with which they transduce target cells varies significantly,in particular their typically poor capacity to transduce primary stem cells. Here we describe the isolation and enrichment of murine bone-marrow mesenchymal stem cells (MSCs) via fluorescence-activated cell sorting (FACS); the cloning,production,and concentration of high-titer second generation lentiviral vectors via combined tangential flow filtration (TFF) and ultracentrifugation; and the subsequent high-efficiency gene modification of MSCs into insulin-producing cells via overexpression of the furin-cleavable human insulin (INS-FUR) gene. View Publication

Human immunodeficiency virus type 1 (HIV-1) eradication is prevented by the establishment on infection of cellular HIV-1 reservoirs that are not fully characterized,especially in genital mucosal tissues (the main HIV-1 entry portal on sexual transmission). Here,we show,using penile tissues from HIV-1-infected individuals under suppressive combination antiretroviral therapy,that urethral macrophages contain integrated HIV-1 DNA,RNA,proteins and intact virions in virus-containing compartment-like structures,whereas viral components remain undetectable in urethral T cells. Moreover,urethral cells specifically release replication-competent infectious HIV-1 following reactivation with the macrophage activator lipopolysaccharide,while the T-cell activator phytohaemagglutinin is ineffective. HIV-1 urethral reservoirs localize preferentially in a subset of polarized macrophages that highly expresses the interleukin-1 receptor,CD206 and interleukin-4 receptor,but not CD163. To our knowledge,these results are the first evidence that human urethral tissue macrophages constitute a principal HIV-1 reservoir. Such findings are determinant for therapeutic strategies aimed at HIV-1 eradication. View Publication

HIV persists in latently infected CD4+ T cells during antiretroviral therapy (ART). Immune checkpoint molecules,including PD-1,are preferentially expressed at the surface of persistently infected cells. However,whether PD-1 plays a functional role in HIV latency and reservoir persistence remains unknown. Using CD4+ T cells from HIV-infected individuals,we show that the engagement of PD-1 inhibits viral production at the transcriptional level and abrogates T-cell receptor (TCR)-induced HIV reactivation in latently infected cells. Conversely,PD-1 blockade with the monoclonal antibody pembrolizumab enhances HIV production in combination with the latency reversing agent bryostatin without increasing T cell activation. Our results suggest that the administration of immune checkpoint blockers to HIV-infected individuals on ART may facilitate latency disruption. View Publication

The bone marrow microenvironment (BMME) contributes to the regulation of hematopoietic stem cell (HSC) function,though its role in age-associated lineage skewing is poorly understood. Here we show that dysfunction of aged marrow macrophages (Mphis) directs HSC platelet-bias. Mphis from the marrow of aged mice and humans exhibited an activated phenotype,with increased expression of inflammatory signals. Aged marrow Mphis also displayed decreased phagocytic function. Senescent neutrophils,typically cleared by marrow Mphis,were markedly increased in aged mice,consistent with functional defects in Mphi phagocytosis and efferocytosis. In aged mice,Interleukin 1B (IL1B) was elevated in the bone marrow and caspase 1 activity,which can process pro-IL1B,was increased in marrow Mphis and neutrophils. Mechanistically,IL1B signaling was necessary and sufficient to induce a platelet bias in HSCs. In young mice,depletion of phagocytic cell populations or loss of the efferocytic receptor Axl expanded platelet-biased HSCs. Our data support a model wherein increased inflammatory signals and decreased phagocytic function of aged marrow Mphis induce the acquisition of platelet bias in aged HSCs. This work highlights the instructive role of Mphis and IL1B in the age-associated lineage-skewing of HSCs,and reveals the therapeutic potential of their manipulation as antigeronic targets. View Publication

In life sciences,the material properties of suspended cells have attained significance close to that of fluorescent markers but with the advantage of label-free and unbiased sample characterization. Until recently,cell rheological measurements were either limited by acquisition throughput,excessive post processing,or low-throughput real-time analysis. Real-time deformability cytometry expanded the application of mechanical cell assays to fast on-the-fly phenotyping of large sample sizes,but has been restricted to single material parameters as the Young's modulus. Here,we introduce dynamic real-time deformability cytometry for comprehensive cell rheological measurements at up to 100 cells per second. Utilizing Fourier decomposition,our microfluidic method is able to disentangle cell response to complex hydrodynamic stress distributions and to determine viscoelastic parameters independent of cell shape. We demonstrate the application of our technology for peripheral blood cells in whole blood samples including the discrimination of B- and CD4+ T-lymphocytes by cell rheological properties. View Publication

Due to their complex chemical and physical properties,the effects and mechanisms of action of natural sources of dietary fiber on the intestine are unclear. Pigs are commonly fed high-fiber diets to reduce production costs and non-starch polysaccharide (NSP)-degrading enzymes have been used to increase fiber digestibility. We evaluated the expression of mucin 2 (MUC2),presence of goblet cells,and ileal immune profile of pigs housed individually for 28 days and fed either a low fiber diet based on corn-soybean meal (CSB,n = 9),or two high fiber diets formulated adding 40{\%} corn distillers' dried grains with solubles (DDGS,n = 9) or 30{\%} wheat middlings (WM,n = 9) to CSB-based diet. Pigs were also fed those diets supplemented with a NSP enzymes mix (E) of xylanase,beta-glucanase,mannanase,and galactosidase (n = 8,10,and 9 for CSB+E,DDGS+E and WM+E,respectively). Feeding DDGS and WM diets increased ileal MUC2 expression compared with CSB diet,and this effect was reversed by the addition of enzymes. There were no differences in abundance of goblet cells among treatments. In general,enzyme supplementation increased gene expression and concentrations of IL-1beta,and reduced the concentrations of IL-4,IL-17A and IL-11. The effects of diet-induced cytokines on modulating intestinal MUC2 were assessed in vitro by treating mouse and swine enteroids with 1 ng/ml of IL-4 and IL-1beta. In accordance with previous studies,treatment with Il-4 induced Muc2 and expansion of goblet cells in mouse enteroids. However,swine enteroids did not change MUC2 expression or number of goblet cells when treated with IL-4 or IL-1beta. Our results suggest that mucin and immune profile are regulated by diet in the swine intestine,but by mechanisms different to mouse,emphasizing the need for using appropriate models to study responses to dietary fiber in swine. View Publication