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Cancer cells can develop an immunosuppressive tumor microenvironment to control tumor-infiltrating lymphocytes. The underlying mechanisms still remain unclear. Here, we report that mouse and human colon cancer cells acquire lymphocyte membrane proteins including cellular markers such as CD4 and CD45. We observed cell populations harboring both a tumor-specific marker and CD4 in the tumor microenvironment. Sorted cells from these populations were capable of forming organoids, identifying them as cancer cells. Live imaging analysis revealed that lymphocyte membrane proteins were transferred to cancer cells via trogocytosis. As a result of the transfer in vivo, cancer cells also acquired immune regulatory surface proteins such as CTLA4 and Tim3, which suppress activation of immune cells [T. L. Walunas et al., Immunity 1, 405–413 (1994) and L. Monney et al., Nature 415, 536–541 (2002)]. RNA sequencing analysis of ex vivo–cocultured splenocytes with trogocytic cancer cells showed reductions in Th1 activation and natural killer cell signaling pathways compared with the nontrogocytic control. Cancer cell trogocytosis was confirmed in the patient-derived xenograft models of colorectal cancer and head and neck cancer. These findings suggest that cancer cells utilize membrane proteins expressed in lymphocytes, which in turn contribute to the development of the immunosuppressive tumor microenvironment. [ABSTRACT FROM AUTHOR]

Significantly higher levels of plasma CXCL13 [chemokine (C-X-Cmotif) ligand 13] were associated with the generation of broadly neutralizing antibodies (bnAbs) against HIV in a large longitudinal cohort of HIV-infected individuals. Germinal centers (GCs) perform the remarkable task of optimizing B-cell Ab responses. GCs are required for almost all B-cell receptor affinity maturation and will be a critical parameter to monitor if HIV bnAbs are to be induced by vaccination. However, lymphoid tissue is rarely available from immunized humans,making themonitoring of GC activity by direct assessment of GC B cells and germinal center CD4+ T follicular helper (GC Tfh) cells problematic. The CXCL13-CXCR5 [chemokine (C-X-C motif) receptor 5] chemokine axis plays a central role in organizing both B-cell follicles and GCs. Because GC Tfh cells can produce CXCL13, we explored the potential use of CXCL13 as a blood biomarker to indicate GC activity. In a series of studies, we found that plasma CXCL13 levels correlated with GC activity in draining lymph nodes of immunized mice, immunized macaques, and HIV-infected humans. Furthermore, plasma CXCL13 levels in immunized humans correlated with the magnitude of Ab responses and the frequency of ICOS+ (inducible T-cell costimulator) Tfh-like cells in blood. Together, these findings support the potential use of CXCL13 as a plasma biomarker of GC activity in human vaccine trials and other clinical settings. [ABSTRACT FROM AUTHOR]

The nuclear hormone receptor retinoic acid-related orphan receptor gamma t (RORγt) is a transcription factor (TF) specific to TH17 cells that produce interleukin (IL)-17 and have been implicated in a wide range of autoimmunitγ. Here, we developed a novel therapeutic strategγ to modulate the functions of RORγt using cell-transducible form of transcription modulation domain of RORγt (tRORγt-TMD), which can be delivered effectivelγ into the nucleus of cells and into the central nerve sγstem (CNS). tRORγt-TMD specificallγ inhibited Tï17-related cγtokines induced bγ RORγt, therebγ suppressing the differentiation of naïve T cells into Tï17, but not into Tï1, Tï2, or Treg cells. tRORγt-TMD injected into experimental autoimmune encephalomγelitis (EAE) animal model can be delivered effectivelγ in the splenic CD4+ T cells and spinal cord-infiltrating CD4+ T cells, and suppress the functions of Tï17 cells. The clinical severitγ and incidence of EAE were ameliorated bγ tRORγt-TMD in preventive and therapeutic manner, and significant reduction of both infiltrating CD4+ IL-17+ T cells and inflammatorγ cells into the CNS was observed. As a result, the number of spinal cord demγelin-ation was also reduced after tRORγt-TMD treatment. With the same proof of concept, tTbet-TMD specificallγ blocking Tï1 differentiation improved the clinical incidence of rheumatoid arthritis (RA). Therefore, tRORγt-TMD and tTbet-TMD can be novel therapeutic reagents with the natural specificitγ for the treatment of inflammatorγ diseases associated with Tï17 or Tï1. This strategγ can be applied to treat various diseases where a specific transcription factor has a keγ role in pathogenesis. [ABSTRACT FROM AUTHOR]

The intrinsic role of endogenous IL-17A in spontaneous intestinal. tumorigenesis has not been addressed, previously to our knowledge. Ablation of IL-17A significantly reduced tumor development in mice bearing a heterozygote mutation in the adenomatous polyposis coli (APC) gene (ApcMin/+ mice). There was also a decrease in inflammatory cytokines and proinflammatory mediators. reduced infiltration of lymphocytes including T cells, and preservation of intestinal architecture and the presence of APC protein in intestinal epithelial cells. Interestingly, lL-17A ablation also corrected immunological abnormalities such as splenomegaly and thymic atrophy in ApcMin/+ mice. CD4 Tcells from ApcMin/+ mice showed hyperproliferative potential in vitro and in vivo and increased levels of IL-17A and IL-b. The effector CD4 T cells from ApcMin/+ mice were more resistant to regulatory T cell-mediated suppression. Finally, these CD4 T cells induced colitis in immunodeficient mice upon adoptive transfer, whereas the ablation of IL-17A in CD4 T cells in ApcMin/+ mice completely abolished this pathogenic potential in vivo. Taken together, our results show that CD4 T cellderived lL-17A promotes spontaneous intestinal tumorigenesis with altered functions of CD4 T cells in ApcMin/+ mice. [ABSTRACT FROM AUTHOR]

CTLA-4 (CD152) negatively regulates T cell activation signaling, and the cytdplasmic domain of CTLA-4 (ctCTLA-4) itself has the capacity to inhibitT cell activation in vitro and in viva. In this study, the inhibitory mechanisms of the cell-permeable recombinant protein Hph-1CtCTLA-4 on I cell activation and its ability to prevent collageninduced arthritis were analyzed. Hph-1-ctCTLA-4 prevented human and mouse I cell activation and proliferation by inhibition of T cell receptor-proximal signaling and the arrest of the cell cycle. Furthermore, Hph-1-ctCTLA-4 protected human umbilical vein endothelial cells (HUVEC) from the human CTL allo-response. The incidence and severity of collagen-induced arthritis were significantly reduced and the erosion of cartilage and bone was effectively prevented by i.v. injection and transdermal administration of Hph-1-ctCTLA-4. Inflammatory cytokine production (IL-β, IL-6, TNF-α, lL-17A) and collagenspecific antibody levels were significantly reduced, and the numbers of activated T cells and infiltrating granulocytes were substantially decreased. These results demonstrate that systemic or transdermal application of a cell-permeable form of the cytoplasmic domain of CTLA-4 offers an effective therapeutic approach for autoimmune diseases such as rheumatoid arthritis. [ABSTRACT FROM AUTHOR]

Regulatory T cells that express the Foxp3 transcription factor play important roles in preventing autoimmune diseases. Although several studies have demonstrated that the lack of the forkhead DNA-binding domain of Foxp3 caused severe autoimmune disease in scurfy mutant mice, the other functional domains of Foxp3 are less well characterized. Here, we show that the deletion of glutamic acid (ΔE250) in the leucine-zipper domain of Foxp3 causes a loss of hyporesponsiveness when compared with wild-type Foxp3 upon antigenic stimulation. CD4 T cells that ectopically express the glutamic acid mutant show significant losses of suppressor activity both in vitro and in viva. We also demonstrate that regulation of both Thiand Th2-type cytokine secretion in CD4 T cells that express wild-type Foxp3 is significantly altered by the deletion of glutamic acid. Defects are also observed in the expression of adhesion molecules, such as L-selectin (CD62L) and CD103, suggesting an important role of glutamic acid in the migratory behavior of regulatory T cells. Finally, this mutation reduces transcriptional repressor activity and impairs the homodimerization of Foxp3. Taken together, our results provide insight into the mechanism that controls autoimmune diseases via the deletion of this single glutamic acid residue in the leucine-zipper domain of Foxp3. [ABSTRACT FROM AUTHOR]

Signal transducer and activator of transcription 3 (STAT3) is a key transcriptional mediator for many cytokines and is essential for normal embryonic development. We have generated a unique strain of mice with tissue-specific disruption of STAT3 in bone marrow cells during hematopoiesis. This specific STAT3 deletion causes death of these mice within 4-6 weeks after birth with Crohn's disease-like pathogenesis in both the small and large intestine, including segmental inflammatory cell infiltration, ulceration, bowel wall thickening, and granuloma formation. Deletion of STAT3 causes significantly increased cell autonomous proliferation of cells of the myeloid lineage, both in vivo and in vitro. Most importantly, Stat3 deletion during hematopoiesis causes overly pseudoactivated innate immune responses. Although inflammatory cytokines, including tumor necrosis factor α and IFN-γ, are overly produced in these mice, the NAPDH oxidase activity, which is involved in antimicrobial and innate immune responses, is inhibited. The signaling responses to lipopolysaccharide are changed in the absence of STAT3, leading to enhanced NF-κB activation. Our results suggest a model in which STAT3 has critical roles in the development and regulation of innate immunity, and deletion of STAT3 during hematopoiesis results in abnormalities in myeloid cells and causes Crohn's disease-like pathogenesis. [ABSTRACT FROM AUTHOR]

Examines the immunosuppressive effects of tautomycetin in activated T cells. Induction of T-cell specific apoptosis; Graft survival of allografted rats treated with cyclosporin; Isolation of human peripheral blood lymphocytes from healthy volunteers.

We have identified conditions for forming cultured human umbilical vein endothelial cells (HUVEC) into tubes within a three-dimensional gel that on implantation into immunoincompetent mice undergo remodeling into complex microvessels lined by human endothelium. HUVEC suspended in mixed collagen/fibronectin gels organize into cords with early lumena by 24 h and then apoptose. Twenty-hour constructs, s.c. implanted in immunodeficient mice, display HUVEC-lined thin-walled microvessels within the gel 31 days after implantation. Retroviral-mediated overexpression of a caspase-resistant Bcl-2 protein delays HUVEC apoptosis in vitro for over 7 days. Bcl-2-transduced HUVEC produce an increased density of HUVEC-lined perfused microvessels in vivo compared with untransduced or control-transduced HUVEC. Remarkably, Bcl-2- but not control-transduced HUVEC recruit an ingrowth of perivascular smooth-muscle alpha-actin-expressing mouse cells at 31 days, which organize by 60 days into HUVEC-lined multilayered structures resembling true microvessels. This system provides an in vivo model for dissecting mechanisms of microvascular remodeling by using genetically modified endothelium. Incorporation of such human endothelial-lined microvessels into engineered synthetic skin may improve graft viability, especially in recipients with impaired angiogenesis.

By using antisense RNA, Lck-deficient transfectants of a T helper 2 (Th2) clone have been derived and shown to have a qualitative defect in the T cell receptor signaling pathway. A striking feature observed only in Lck-deficient T cells was the presence of a constitutively tyrosine-phosphorylated 32-kDa protein. In the present study, we provide evidence that this aberrantly hyperphosphorylated protein is p34(cdc2) (cdc2) a key regulator of cell-cycle progression. Lck-deficient transfectants expressed high levels of cdc2 protein and its regulatory units, cyclins A and B. The majority of cdc2, however, was tyrosine-phosphorylated and therefore enzymatically inactive. The transfectants were significantly larger than the parental cells and contained 4N DNA. These results establish that a deficiency in Lck leads to a cell-cycle arrest in G2. Moreover, transfected cells were hypersusceptible to apoptosis when activated through the T cell receptor. Importantly, however, this hypersusceptibility was largely reversed in the presence of T cell growth factors. These findings provide evidence that, in mature T lymphocytes, cell-cycle progression through the G2-M check point requires expression of the Src-family protein tyrosine kinase, Lck. This requirement is Lck-specific; it is observed under conditions in which the closely related Fyn kinase is expressed normally, evincing against a redundancy of function between these two kinases.

Split-thickness pig skin was transplanted on severe combined immunodeficient mice so that pig dermal microvessels spontaneously inosculated with mouse microvessels and functioned to perfuse the grafts. Pig endothelial cells in the healed grafts constitutively expressed class I and class II major histocompatibility complex molecules. Major histocompatibility complex molecule expression could be further increased by intradermal injection of pig interferon-gamma (IFN-gamma) but not human IFN-gamma or tumor necrosis factor. Grafts injected with pig IFN-gamma also developed a sparse infiltrate of mouse neutrophils and eosinophils without evidence of injury. Introduction of human peripheral blood mononuclear cells into the animals by intraperitoneal inoculation resulted in sparse perivascular mononuclear cell infiltrates in the grafts confined to the pig dermis. Injection of pig skin grafts on mice that received human peripheral blood mononuclear cells with pig IFN-gamma (but not human IFN-gamma or heat-inactivated pig IFN-gamma) induced human CD4(+) and CD8(+) T cells and macrophages to more extensively infiltrate the pig skin grafts and injure pig dermal microvessels. These findings suggest that human T cell-mediated rejection of xenotransplanted pig organs may be prevented if cellular sources of pig interferon (e.g., passenger lymphocytes) are eliminated from the graft.