Zhinan Yin

The Growth Factor Progranulin Binds to TNF Receptors and Is Therapeutic Against Inflammatory Arthritis in Mice

A growth factor protects against arthritis in mice by blocking tumor necrosis factor–dependent signaling. The growth factor progranulin (PGRN) has been implicated in embryonic development, tissue repair, tumorigenesis, and inflammation, but its receptors remain unidentified. We report that PGRN bound directly to tumor necrosis factor receptors (TNFRs) and disturbed the TNFα-TNFR interaction. PGRN-deficient mice were susceptible to collagen-induced arthritis, and administration of PGRN reversed inflammatory arthritis. Atsttrin, an engineered protein composed of three PGRN fragments, exhibited selective TNFR binding. PGRN and Atsttrin prevented inflammation in multiple arthritis mouse models and inhibited TNFα-activated intracellular signaling. Collectively, these findings demonstrate that PGRN is a ligand of TNFR, an antagonist of TNFα signaling, and plays a critical role in the pathogenesis of inflammatory arthritis in mice. They also suggest new potential therapeutic interventions for various TNFα-mediated pathologies and conditions, including rheumatoid arthritis.

STAT3 deletion during hematopoiesis causes Crohn's disease-like pathogenesis and lethality : a critical role of STAT3 in innate immunity

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 Crohns 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 Crohns disease-like pathogenesis.

γδ T Cells Provide an Early Source of Interferon γ in Tumor Immunity

Interferon (IFN)-γ is necessary for tumor immunity, however, its initial cellular source is unknown. Because γδ T cells primarily produce this cytokine upon activation, we hypothesized that they would provide an important early source of IFN-γ in tumor immunosurveillance. To address this hypothesis, we first demonstrated that γδ T cell–deficient mice had a significantly higher incidence of tumor development after challenge with a chemical carcinogen methylcholanthrene (MCA) or inoculation with the melanoma cell line B16. In wild-type mice, γδ T cells were recruited to the site of tumor as early as day 3 after inoculation, followed by αβ T cells at day 5. We then used bone marrow chimeras and fetal liver reconstitutions to create mice with an intact γδ T cell repertoire but one that was specifically deficient in the capacity to produce IFN-γ. Such mice had a higher incidence of tumor development, induced either with MCA or by inoculation of B16 melanoma cells, compared with mice with IFN-γ–competent γδ T cells. Moreover, genetic deficiency of γδ T cells resulted in impaired IFN-γ production by tumor antigen-triggered αβ T cell upon immunization with tumor lysate. These results demonstrate that γδ T cells can play a necessary role in tumor immunity through provision of an early source of IFN-γ that in turn may regulate the function of tumor-triggered αβ T cells.

IL-10 Regulates Murine Lupus

MRL/MpJ-Tnfrsf6lpr (MRL/MpJ-Faslpr; MRL-Faslpr) mice develop a spontaneous lupus syndrome closely resembling human systemic lupus erythematosus. To define the role of IL-10 in the regulation of murine lupus, IL-10 gene-deficient (IL-10−/−) MRL-Faslpr (MRL-Faslpr IL-10−/−) mice were generated and their disease phenotype was compared with littermates with one or two copies of an intact IL-10 locus (MRL-Faslpr IL-10+/− and MRL-Faslpr IL-10+/+ mice, respectively). MRL-Faslpr IL-10−/− mice developed severe lupus, with earlier appearance of skin lesions, increased lymphadenopathy, more severe glomerulonephritis, and higher mortality than their IL-10-intact littermate controls. The increased severity of lupus in MRL-Faslpr IL-10−/− mice was closely associated with enhanced IFN-γ production by both CD4+ and CD8+ cells and increased serum concentration of IgG2a anti-dsDNA autoantibodies. The protective effect of IL-10 in this lupus model was further supported by the observation that administration of rIL-10 reduced IgG2a anti-dsDNA autoantibody production in wild-type MRL-Faslpr animals. In summary, our results provide evidence that IL-10 can down-modulate murine lupus through inhibition of pathogenic Th1 cytokine responses. Modulation of the level of IL-10 may be of potential therapeutic benefit for human lupus.

IFN-γ-Producing γδ T Cells Help Control Murine West Nile Virus Infection

West Nile (WN) virus causes fatal meningoencephalitis in laboratory mice, thereby partially mimicking human disease. Using this model, we have demonstrated that mice deficient in γδ T cells are more susceptible to WN virus infection. TCRδ−/− mice have elevated viral loads and greater dissemination of the pathogen to the CNS. In wild-type mice, γδ T cells expanded significantly during WN virus infection, produced IFN-γ in ex vivo assays, and enhanced perforin expression by splenic T cells. Adoptive transfer of γδ T cells to TCRδ−/− mice reduced the susceptibility of these mice to WN virus, and this effect was primarily due to IFN-γ-producing γδ T cells. These data demonstrate a distinct role for γδ T cells in the control of and prevention of mortality from murine WN virus infection.

The inhibition of tumor growth and metastasis by self-assembled nanofibers of taxol

Molecular hydrogels have big potential for local delivery and sustained release of therapeutic agents. In this paper, we reported on a molecular hydrogel mainly formed by the widely used anti-cancer drug of taxol. The hydrogel was formed by an ester bond hydrolysis process from a taxol derivative (Taxol-SA-GSSG, 1) and could be administrated into solid tumors to dramatically hinder their growths and prevent their metastasis. Besides the improved anti-cancer effect compared to the clinically used intravenous (i.v.) injection of Taxol(®), the concentration of taxol in blood was low due to the local administration of taxol hydrogels, which greatly enhanced the dosage tolerance of mice to taxol and might reduce side effects of taxol during chemotherapy. Our observations suggested that the hydrogel mainly composed of taxol would have great potential for its practical applications.

Helicobacter pylori-Induced Th17 Responses Modulate Th1 Cell Responses, Benefit Bacterial Growth, and Contribute to Pathology in Mice

CD4+ T cell responses are critical for the pathogenesis of Helicobacter pylori infection. The present study evaluated the role of the Th17 subset in H. pylori infection. H. pylori infection induced significant expression of IL-17 and IFN-γ in mouse gastric tissue. IL-23 and IL-12 were increased in the gastric tissue and in H. pylori-stimulated macrophages. Cell responses were examined by intracellular staining for IFN-γ, IL-4, and IL-17. Mice infected with H. pylori developed a mixed Th17/Th1 response; Th17 responses preceded Th1 responses. Treatment of mice with an anti–IL-17 Ab but not a control Ab significantly reduced the H. pylori burden and inflammation in the stomach. H. pylori colonization and gastric inflammation were also lower in IL-17−/− mice. Furthermore, administration of recombinant adenovirus encoding mouse IL-17 increased both H. pylori load and inflammation. Further analysis showed that the Th1 cell responses to H. pylori were downregulated when IL-17 is deficient. These results together suggest that H. pylori infection induces a mixed Th17/Th1 cell response and the Th17/IL-17 pathway modulates Th1 cell responses and contributes to pathology.

Pivotal Role of Reduced let-7g Expression in Breast Cancer Invasion and Metastasis

Screening of the entire let-7 family of microRNAs (miRNA) by in situ hybridization identified let-7g as the only member, the diminished expression of which was significantly associated with lymph node metastasis and poor survival in breast cancer patients. Abrogation of let-7g expression in otherwise nonmetastatic mammary carcinoma cells elicited rapid metastasis from the orthotopic location, through preferential targets, Grb2-associated binding protein 2 (GAB2) and fibronectin 1 (FN1), and consequent activation of p44/42 mitogen-activated protein kinase (MAPK) and specific matrix metalloproteinases. Treatment with estrogen or epidermal growth factor specifically reduced the expression of mature let-7g through activation of p44/42 MAPK and subsequently stimulated expression of GAB2 and FN1, which, in turn, promoted tumor invasion. We thus identify let-7g as a unique member of the let-7 miRNA family that can serve as a prognostic biomarker in breast cancer and also propose a paradigm used by specific signaling molecules via let-7g to cooperatively promote breast cancer invasion and metastasis. Thus, let-7 family members neither possess equivalent clinicopathologic correlation nor function in breast cancer.

T-Bet Expression and Failure of GATA-3 Cross-Regulation Lead to Default Production of IFN-γ by γδ T Cells

γδ T cells predominantly produce IFN-γ upon activation. To determine the basis for default production of IFN-γ by γδ T cells, we analyzed the transcription factors T-box expressed in T cells (T-bet) and GATA-3. T-bet, absent in naive γδ cells, was induced upon TCR signaling, with IFN-γ production. T-bet also regulated IL-4 synthesis, as γδ cells isolated from T-bet-deficient mice displayed enhanced IL-4 levels with reduced IFN-γ production. Notably, T-bet expression after TCR signaling in γδ cells was not down-regulated by IL-4, in conjunction with a higher ratio of T-bet:GATA-3 expression than that found in CD4+ T cells. Indeed, overexpression of GATA-3 failed to inhibit IFN-γ secretion in γδ cells to the degree seen in CD4+ T cells. These results indicate that T-bet enhances IFN-γ secretion and suppresses IL-4 secretion in γδ cells, and that GATA-3 fails to counterbalance T-bet-mediated IFN-γ production, accounting for the default synthesis of IFN-γ by these T lymphocytes.

A small-molecule macrophage migration inhibitory factor antagonist protects against glomerulonephritis in lupus-prone NZB/NZW F1 and MRL/lpr mice.

Autoimmunity leads to the activation of innate effector pathways, proinflammatory cytokine production, and end-organ injury. Macrophage migration inhibitory factor (MIF) is an upstream activator of the innate response that mediates the recruitment and retention of monocytes via CD74 and associated chemokine receptors, and it has a role in the maintenance of B lymphocytes. High-expression MIF alleles also are associated with end-organ damage in different autoimmune diseases. We assessed the therapeutic efficacy of (S,R)-3-(4-hydroxyphenyl)-4,5-dihydro-5-isoxazole acetic acid methyl ester (ISO-1), an orally bioavailable MIF antagonist, in two distinct models of systemic lupus erythematosus: the NZB/NZW F1 and the MRL/lpr mouse strains. ISO-1, like anti-MIF, inhibited the interaction between MIF and its receptor, CD74, and in each model of disease, it reduced functional and histological indices of glomerulonephritis, CD74+ and CXCR4+ leukocyte recruitment, and proinflammatory cytokine and chemokine expression. Neither autoantibody production nor T and B cell activation were significantly affected, pointing to the specificity of MIF antagonism in reducing excessive proinflammatory responses. These data highlight the feasibility of targeting the MIF–MIF receptor interaction by small-molecule antagonism and support the therapeutic value of downregulating MIF-dependent pathways of tissue damage in systemic lupus erythematosus.