Larry R. Ellingsworth

γ‐Interferon‐Induced Activation of Latent Transforming Growth Factor‐β by Human Monocytes

Transforming growth factor-ps (TGFps), a family of at least four different homologous disulfide-linked homodimeric polypeptides, are potent modulators of cell growth and differentiation.’-3 Analysis of cDNA clones encoding mammalian TGFPs and appropriate cell culture supernatants indicates that the mature molecule is cleaved from the carboxy terminus of a larger glycosylated precurso+6 and is secreted in a latent, inactive form?-9 Transient acidification activates E F P ; however, the physiological mechanism(s) of TGFB secretion and activation, which initiate its potent autocrine and paracrine effects in vivo, are poorly understood. In this study, we asked whether cell association was involved in activation of ‘EFp. The ’’latentrecombinant complex used contains one dimeric TGFpl molecule associated with a disulfide-bonded dimeric remnant of the precursor. Fresh human monocytes stimulated by y-interferon (yIFN), activates the “latent” recombinant E F P l complex ( L m F P l ) in a dose-dependent manner. The activated X F p l released into the media is neutralized by a TGFPl monoclonal antibody and has a mass (24 kD) identical to native TGFB1. Thus, TGFSl activation by monocytes may require y IFN-mediated gene expression as well as a cell-associated processing event. We have recently reported the expression of simian ‘EFP type 1 cDNAIO in Chinese hamster ovary (CHO) cells using dehydrofolate reductase (dhfr) gene amplification.” One CHO cell transfectant, designated clone 17, secretes mg amounts of latent

Hematologic and Hematopoietic Changes Induced by Systemic Administration of TGFβ1

Transforming growth factor-p (TGFP) is a family of pleiotropic proteins found in relatively large amounts in bone and platelets. Its presence in these sites, and their immunohistochemical localization in fetal hematopoietic sites2 suggest that they may be important regulators of hematopoiesis. This notion is supported by in v i m data showing TGFP can inhibit platelet, red cell, and plasma cell precursor differentiat i ~ n ~ ~ , as well as mature lymphocyte The present studies were carried out to investigate whether daily, subcutaneous administration of high doses of TGFPI to mice over a 2-wk period affects a variety of hematologic parameters in the peripheral blood and in the primary and secondary lymphoid organs. The results show a decrease in mature red cells at all levels and in peripheral platelet counts, along with an increase in white cell counts. Granulopoiesis occurred in the spleen and bone marrow, but no significant changes occurred in peripheral blood neutrophil counts. The data suggest that high doses of TGFPl administered subcutaneously can systemically regulate selective murine hematologic pathways.

Transforming Growth Factor-Β in Psoriasis: Pathogenesis and Therapy

Psoriasis is a common skin disease, affecting 1 to 2 % of the U.S. population at a cost of some 1.5 billion dollars per year.’ Psoriasis is characterized by marked increases in keratinocyte proliferation? abnormal patterns of keratinocyte differentiation? prominent alterations in dermal capillary vasculature~ and the presence of dermal and epidermal T cells, monocytehacrophages, and polymorphonuclear leukocytes?.6 We have recently shown that expression of transforming growth factor-a (TGF-a) is markedly increased in psoriatic lesions: This result, coupled with the fluctuating clinical course of psoriasis, suggests that the molecular pathogenesis of psoriasis may involve unstable or altered regulation of TGF-a and possibly other epidermally derived cytokines, such as interleukin-6 (IL-6).8 Transforming growth factor-p (TCF-P) acts synergistically with TCF-a to promote anchorage-independent growth of certain cell types? However, it has potent antiproliferative effects upon a variety of epithelial cell types in vitro,’O including keratinocytes.“ In human keratinocytes, TGF-P causes a reversible inhibition of proliferation, predominantly in the GI phase of the cell cycle.I2 On the basis of these results, it has been hypothesized that TGF-p functions as a negative growth regulator in normal skin.ll,12 Given the marked keratinocyte hyperproliferation characteristic of psoriasis, it is possible that psoriatic keratinocytes could be deficient in either the production of or responsiveness to TGF-p, resulting in a deficient state of growth regulation. We have tested this hypothesis in several different ways with respect to TGF-P1, the first member of the TGF-0 gene family to be molecularly cloned and biochemically characterized. First, we have compared the expression of TGF-01 mRNA in normal and psoriatic epidermis by Northern blotting. These results confirm those already reported using a slot blot procedure? Second, we have compared the responsiveness of keratinocytes cultured from the skin of normal individuals and from psoriatic lesions to purified TCF-pl. The responses studied include TGF-p1-induced alterations in c-myc and plasminogen activator inhibitor-1 (PAI-1) mRNA levels as well as the proliferative response.

Two Forms of Transforming Growth Factor-β Are Equally Potent Selective Growth Inhibitors of Early Murine Hematopoiesisab

This project has been funded at least in part with Federal funds from the Department of Health and Human Services under contract number N01-CO-74102. The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of tradenames, commercial products, or organizations imply endorsement by the U.S. Government. By acceptance of this article, the publisher or recipient acknowledges the right of the U.S. Government to retain a nonexclusive, royalty-free license in and to any copyright covering the article. To whom reprint requests should be addressed.

In Vivo Effects of TGFβ on the Cellular and Humoral Response to an Allogeneic Tumor in Mice

Transforming growth factor-@ (TGFP1) has been shown to inhibit a number of mature immune cell functions in vitro. These include T and B cell proliferation, B cell immunoglobulin secretion, T cell IL-2 production and IL-2 receptor expression, and NK and T cell cytolytic Macrophage function has been shown to be both increased and decreased in different in vitro m0delsP3~ These in vitro studies, while useful in dissecting distinct activities of TGFD, may not take into account many of the cellular interactions that occur in vivo during an immune response. The present study makes use of the immune response to an intraperitoneal (i.p.) allogeneic tumor challenge in mice to test the in vivo immunosuppressive effects of TGFP1. The data indicate that daily, subcutaneous treatments with 5 pg or more of TGFPl inhibit the splenic cytolytic T lymphocyte (CTL) response, but not the serum antibody (Ab) response seen 11 days after immunization. The results suggest that under these conditions subcutaneous TGFPl treatments result in systemic suppression of distinct arms of the immune response.

Synergy between transforming growth factor-β and tumor necrosis factor-α in the induction of monocytic differentiation of human leukemic cell lines

E F P is a well known regulator of cell proliferation. In contrast, much less is known about the ability of WFO to affect cellular differentiation, although it has been shown that TGFj3 can induce terminal differentiation of bronchial epithelial cells. We have investigated whether TGFP plays a role in the regulation of proliferation and differentiation of two human leukemic cell lines: the promyelocytic cell line HL-60 and the monoblastic cell line U937.