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After weaning, during mammary gland involution, milk-producing mammary epithelial cells undergo apoptosis. Effective clearance of these dying cells is essential, as persistent apoptotic cells have a negative impact on gland homeostasis, future lactation and cancer susceptibility. In mice, apoptotic cells are cleared by the neighboring epithelium, yet little is known about how mammary epithelial cells become phagocytic or whether this function is conserved between species. Here we use a rat model of weaning-induced involution and involuting breast tissue from women, to demonstrate apoptotic cells within luminal epithelial cells and epithelial expression of the scavenger mannose receptor, suggesting conservation of phagocytosis by epithelial cells. In the rat, epithelial transforming growth factor-β (TGF-β) signaling is increased during involution, a pathway known to promote phagocytic capability. To test whether TGF-β enhances the phagocytic ability of mammary epithelial cells, non-transformed murine mammary epithelial EpH4 cells were cultured to achieve tight junction impermeability, such as occurs during lactation. TGF-β3 treatment promoted loss of tight junction impermeability, reorganization and cleavage of the adherens junction protein E-cadherin (E-cad), and phagocytosis. Phagocytosis correlated with junction disruption, suggesting junction reorganization is necessary for phagocytosis by epithelial cells. Supporting this hypothesis, epithelial cell E-cad reorganization and cleavage were observed in rat and human involuting mammary glands. Further, in the rat, E-cad cleavage correlated with increased γ-secretase activity and β-catenin nuclear localization. In vitro, pharmacologic inhibitors of γ-secretase or β-catenin reduced the effect of TGF-β3 on phagocytosis to near baseline levels. However, β-catenin signaling through LiCl treatment did not enhance phagocytic capacity, suggesting a model in which both reorganization of cell junctions and β-catenin signaling contribute to phagocytosis downstream of TGF-β3. Our data provide insight into how mammary epithelial cells contribute to apoptotic cell clearance, and in light of the negative consequences of impaired apoptotic cell clearance during involution, may shed light on involution-associated breast pathologies.

Transforming growth factor (TGF)-beta plays a central role in fibrosis, contributing both to the influx and activation of inflammatory cells, as well as to activation of fibroblasts to elaborate extracellular matrix. In the past few years, new insight has been gained into signal transduction pathways downstream of the TGF-beta receptor serine-threonine kinases with the identification of a family of evolutionarily conserved Smad proteins. Two receptor-activated Smad proteins, Smad2 and Smad3, are phosphorylated by the activated TGF-beta type I receptor kinase, after which they partner with the common mediator, Smad4, and are translocated to the nucleus to where they participate in transcriptional complexes to control expression of target genes. We have shown in wound healing studies of mice null for Smad3, that loss of this key signaling intermediate interferes with the chemotaxis of inflammatory cells to TGF-beta as well as with their ability to autoinduce TGF-beta. Moreover, studies with mouse embryo fibroblasts null for Smad3 show that TGF-beta-dependent induction of c-Jun and c-Fos, important in induction of collagen as well as in autoinduction of TGF-beta, is mediated by Smad3. Based on these observations, we hypothesize that loss of Smad3 will confer resistance to fibrosis and result in reduced inflammatory cell infiltrates, reduced autoinduction of TGF-beta, important to sustain the process, and reduced elaboration of collagen. Preliminary observations in a model of radiation-induced fibrosis confirm this hypothesis and suggest that inhibitors of Smad3 might have clinical application both to improve wound healing and to reduce fibrosis.

Three isoforms of transforming growth factor-beta (TGF-beta) are found in mammalian cells and are potent regulators of inflammation, connective tissue synthesis, cellular proliferation, and differentiation. To determine the distribution and regulation of TGF-beta isoforms during pulmonary injury, a rat model of bleomycin-induced lung inflammation and repair was used. Using immunohistochemistry, we demonstrate that TGF-beta 2 and TGF-beta 3 were localized to alveolar macrophages as well as epithelial and smooth muscle cells of both normal rat lungs and rat lungs obtained at all time intervals after bleomycin administration. Early in bleomycin-induced lung injury, when there is active proliferation of type II alveolar epithelial cells, there was an increase in the number of type II alveolar epithelial cells isolated per lung and an increase in DNA synthesis by explanted type II alveolar epithelial cells. At this time, the secretion of biologically active TGF-beta 1–3, which are potent inhibitors of epithelial cell proliferation, was decreased. However, the secretion of TGF-beta 1–3 activity was markedly increased later in the injury response and coincided with a reduction in the number of type II alveolar epithelial cells isolated per lung and DNA synthesis in vitro. Furthermore, the addition of TGF-beta 1, 2, and 3 to cultures of actively proliferating type II alveolar epithelial cells resulted in inhibition of [3H]thymidine incorporation, whereas, in the presence of anti-TGF-beta 1-3 antibody, there was an increase in [3H]thymidine incorporation. Our findings suggest that altered secretion of TGF-beta 1-3 activity by type II alveolar epithelial cells during bleomycin-induced lung injury may regulate pulmonary alveolar epithelial cell proliferation during injury and repair phases.

The transforming growth factors beta (TGF-beta), a family of regulatory polypeptides, are involved in numerous vital processes including inflammation and wound healing. Since repair of a peripheral nerve lesion includes a series of well-defined steps of cellular actions possibly controlled by TGF-beta s, and since TGF-beta mRNA and immunoreactivity have been found in the normal peripheral nerve, we have examined in the lesioned peripheral nerve. Sciatic nerves of adult rats were either crushed (allowing axonal regeneration) or transfected (to prevent axonal regeneration and to induce Wallerian degeneration in the distal stump). After intervals of 6 hours, 2 and 6 days post-lesion, the rats were sacrificed and each nerve was cut into four segments, two proximal and two distal to the lesion site. TGF-beta 1-3 mRNA were determined for each segment. We demonstrate that TGF-beta 1 mRNA levels are higher than those of TGF-beta 3; the amplitude of mRNA regulation depends on time, type of lesion and localization relative to the lesion site. TGF-beta 2 mRNA could not be detected. For TGF-beta 1-3 immunocytochemistry, animals were sacrificed 12, 24, 48, 72 hours and 7 and 14 days after surgery. TGF-beta immunoreactivity (IR) was observed for all isoforms in lesioned and unlesioned nerves. In the segment directly adjacent to the lesion at its proximal side, an increase of TGF-beta-IR became apparent as soon as 12 hours after surgery; it remained elevated during the whole period observed in both models. In the segment adjoining the distal side of the lesion, an increase of TGF-beta-IR was observed after 48 hours, which was still present after 14 days. At day 7 after crush or transection, an increase of TGF-beta-IR was detected in the most distal segments, which reached its highest levels at the end of our observation period. Our results suggest that the presence of axonal contact might induce an enhancement of TGF-beta expression by Schwann cells in the distal stump of a lesioned and regenerating peripheral nerve. Since we demonstrate an increase of TGF-beta mRNA and protein expression also in the distal stump of transected nerves where Schwann cells are not able to contact sprouting axons from the proximal part, other regulatory pathways must exist. The acquisition of a "reactive" Schwann cell phenotype after peripheral nerve lesion might involve an upregulation of TGF-beta expression.

The use of isoform-specific transforming growth factor-beta (TGF beta) primers, 35S-labeled 40-mer oligonucleotide probes and polyclonal antibodies, reverse transcription-polymerase chain reaction, in situ hybridization, and immunohistochemical observations has revealed that human uterine tissue at various reproductive stages expresses TGF beta s and TGF beta type II receptor messenger RNAs (mRNAs) and proteins. The reverse transcription-polymerase chain reaction revealed the predicted 443-, 310-, 524-, and 431-basepair fragments for TGF beta 1, TGF beta 2, TGF beta 3, and TGF beta type II receptor, respectively, in both endometrial and myometrial tissues, which were further verified by restriction enzyme analysis. In situ hybridization and immunohistochemical observations indicated that all uterine cell types express TGF beta s mRNAs and proteins. In the functionalis region, endometrial luminal and glandular epithelial cells are the primary cell types expressing TGF beta s mRNAs and proteins, with lesser expression in stromal cells, whereas in the basalis region, they are equally expressed in both cell types. In myometrium, TGF beta mRNA and protein expression in smooth muscle cells occurs at a substantially lower level than in endometrial tissue. In endometrial tissue, the highest level of TGF beta mRNA and protein expression appeared in the late proliferative and early to midsecretory phases of the menstrual cycle, with a considerable reduction during the late secretory and postmenopausal periods. The pattern and cellular distribution of TGF beta type II receptor protein were similar to those seen with TGF beta isoforms in both endometrial and myometrial tissues. Quantitative autoradiography (net grain density per 100 microns 2) of specific binding of [125I]TGF beta 1 for different uterine cell types indicated that the stromal cells contain a higher grain density than other uterine cell types (P < 0.05), without a significantly different density in the proliferative, compared with the secretory, phase of the menstrual cycle. These data suggest that TGF beta s acting through their specific receptors may play an important role in a variety of uterine functions in an autocrine/paracrine manner, and ovarian steroids may also regulate their expression in endometrial tissue.

Expression of beta-type transforming growth factor genes (TGF beta 2 and TGF beta 3) in the mouse uterus during the periimplantation period and in response to an acute exposure to 17 beta-estradiol (E2) and progesterone (P4) was studied using Northern blot hybridization and/or immunocytochemistry. Polyclonal antipeptide antibodies specific for TGF beta 2 or TGF beta 3 were employed for immunocytochemistry. In the preimplantation uterus [days (D) 1-4 of pregnancy; day 1 = vaginal plug], immunostaining for TGF beta 2 was observed in luminal and glandular epithelia as well as in myometrium and vascular smooth muscle. In the postimplantation period (D5-D8), TGF beta 2 immunostaining was also detected in decidual cells. In contrast, TGF beta 3 immunostaining was restricted to the myometrium and vascular smooth muscle throughout the periimplantation period (D1-D8). Antisense TGF beta 2 and TGF beta 3 RNA probes were employed for Northern blotting. Northern blot hybridization revealed four TGF beta 2 transcripts (approximately 6.0, 5.0, 4.0, and 3.5 kilobases) in total uterine poly(A)+ RNA on D1-D6 and in poly(A)+ RNA from the deciduum and myometrium collected on D7 and D8 of pregnancy. These TGF beta 2 transcripts were also detected in isolated samples of deciduomata or myometrium obtained from D8 pseudopregnant mice in which the decidual cell reaction was induced experimentally on D4. The levels of these transcripts remained relatively constant during the periimplantation period. Northern blot analysis detected a 3.8-kilobase TGF beta 3 transcript in total uterine poly(A)+ RNA on D1-D6. This transcript was detected in myometrial RNA samples on D7 and D8 of pregnancy or D8 of pseudopregnancy, but was not detected in RNA from the deciduum on D7 and D8 or in that from deciduomata on D8. The effects of ovarian steroids on TGF beta 2 and TGF beta 3 mRNAs were examined in uteri of adult ovariectomized mice. Uterine TGF beta 2 or TGF beta 3 mRNA persisted in ovariectomized mice. However, an injection of E2 induced a rapid (6 h), but transient, induction (approximately 3- to 4-fold) of TGF beta 2 mRNA. An injection of P4 had no effect on TGF beta 2 mRNA levels, and coinjection of P4 with E2 did not antagonize the E2-stimulated transient accumulation of TGF beta 2 mRNA. In comparison, neither an injection of E2 nor one of P4 exerted significant effects on TGF beta 3 mRNA levels.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunohistochemical studies were performed using specific polyclonal antibodies to transforming growth factor (TGF)-beta 1 and TGF-beta 2 to determine their presence and cellular localization in human ovarian tissues of various reproductive states. In the small ovarian follicles, the immunostaining for TGF-beta 1 was present in oocytes, follicle cells, and granulosa and theca cell layers. The level of immunostaining associated with granulosa and theca cell layers intensified as the size of the follicles increased. In the luteal tissue, both the small and large luteal cells immunostained for TGF-beta 1 and their intensities were similar to theca and granulosa cell layers, respectively. The patterns of immunostaining were similar in early (days 14-19), mid (days 22-25), and late (days 26-29) luteal phases; however, the intensity was highest at mid and decreased at late luteal phase. Corpus albicans showed a very weak immunostaining for TGF-beta 1, whereas ectopic pregnancy small luteal cells immunostained relatively intensely. The ovarian stromal, luteal tissue fibroblasts, and arterioles endothelial and smooth muscle cells were also immunostained for TGF-beta 1. The immunostaining of the ovarian tissues for TGF-beta 2 indicated that the theca cell layers were the exclusive cells in the follicles with intense immunostaining, which increased in the larger follicles. A low immunostaining was also observed in granulosa cell of the large follicles. In the luteal tissues, only small luteal cells showed intense immunostaining for TGF-beta 2, which was similar in intensity to that in the theca cells; however, the large luteal cells showed a low level of immunostaining at midluteal phase. The small luteal cells in corpus albicans and ectopic pregnancy luteal tissues retained their immunostaining for TGF-beta 2, but with lower intensity. Endothelial and smooth muscle cells of arterioles also immunostained for TGF-beta 2, but not ovarian stromal cells. Atretic follicles showed very low or no detectable immunostaining for TGF-beta 1 or TGF-beta 2. The results of present studies show that human ovarian tissue at all the reproductive states locally produces TGF-beta 1 and TGF-beta 2, and although TGF-beta 1 is present in most major ovarian cell types, TGF-beta 2 is only produced by theca cells in the follicles and small luteal cells in luteal tissues.

Postimplantation murine decidual tissue from allopregnant C3H mice has been shown to release in vitro a potent immunosuppressive factor closely related to transforming growth factor (TGF)-beta 2 but slightly lower in apparent molecular weight. Decidual suppressor factor (DSF) activity was first detected in decidual tissue supernatant at day 9.5 of gestation and reached a plateau by day 10.5 to 12.5. By Northern analysis of decidual and placental tissue with a simian TGF-beta 2 probe, two characteristic TGF-beta 2 mRNA transcripts were detected in decidual tissue. In situ hybridization analysis of C3H implant sites, with the simian (pGEM-G1G2) TGF-beta 2 riboprobe, revealed a small population of TGF-beta 2+ cells localized to postimplantation decidua basalis and metrial gland cell area after day 8.5. On and before day 8.5, when DSF was not detectable, few TGF-beta 2 mRNA+ cells were detected. To test for TGF-beta release in situ, sections of uterine tissue were stained with antibody specific for TGF-beta 2, that identified DSF in Western blots. In postimplantation tissues (day 9.5, 12.5) patchy anti-TGF-beta 2 staining was seen over decidual tissue. Before day 9.5, slight and diffuse staining over decidual tissue was present with more marked staining of extradecidual tissue. Very little staining was noted over day 9.5 decidual tissue by using anti-TGF-beta 1 antibody as a control; however, some staining was seen over postimplantation fetal trophoblast and myometrial tissue. Fractionation of disaggregated postimplantation decidua by velocity sedimentation revealed that TGF-beta 2 mRNA+ cells were predominantly small and sedimented in the same fraction(s) as those cells previously shown to release DSF in vitro. Thus, the release of TGF-beta 2 related DSF correlates with the in situ detection of TGF-beta 2 mRNA and the in situ release of TGF-beta 2 peptide. These studies suggest that DSF may be a form of TGF-beta 2 released by a population of small lymphocytic decidual suppressor cells.

Transforming growth factor-beta 1 (TGF-beta 1) is a multifunctional cytokine with immunosuppressive effects on T cells in vitro. Experimental allergic encephalomyelitis is an archetypal T cell-mediated autoimmune demyelinating disease of the central nervous system that often serves as a model for multiple sclerosis. In vivo administration of TGF-beta 1 into SJL mice was successful in reducing the incidence of clinical disease and the histologic severity of inflammation and demyelination in the brain and spinal cord. Immunohistochemical studies performed on control animals showed that TGF-beta-1, -2, and -3 were present in inflammatory perivascular lesions in the brain. The use of a naturally occurring cytokine with immunoregulatory functions in the treatment of an autoimmune disease is novel. However, potential long term complications of such therapy must be addressed before its use in human autoimmune disease such as multiple sclerosis.

Non-T small lymphocytic suppressor cells in murine allopregnancy release a potent immunosuppressive factor in vitro that is neutralized by rabbit anti-transforming growth factor (TGF)-beta. Previous studies have suggested that the decidual suppressor factor (DSF) is smaller than TGF-beta 1, and in this paper, we show that DSF on HPLC-sieving columns also elutes later than TGF-beta 2. Nevertheless, DSF has the ability to promote anchorage-independent growth of NRK fibroblasts similar to TGF-beta s. Using turkey antibodies specific for TGF-beta 1 or beta 2, we show that DSF is related to TGF-beta 2 rather than TGF-beta 1, and this relationship was confirmed by using a panel of murine mAb to TGF-subtypes. PAGE and Western blotting showed that the TGF-beta 2-reactive molecules in HPLC-purified DSF was slightly smaller than TGF-beta 2 and approximately 20 to 23 kDa. The DSF molecule is therefore closely related to TGF-beta 2 but as released from decidua, differs in size. The TGF-beta 2-related decidual suppressor factor was also obtained from the decidua of synpregnant C.B.-17 severe combined immune deficiency (SCID) and pregnant SCID-BG (C57BL/6 background) mice, confirming the lack of T or B cell dependence of DSF production and the generality of production of a TGF-beta-related suppressor factor by decidua associated with successful pregnancy in mice.

The main cause of late graft loss or declining long-term graft function is chronic allograft nephropathy (CAN), characterized by progressive interstitial fibrosis. Transforming growth factor (TGF)-beta1 plays a key role in fibrogenesis. We immunohistochemically investigated whether the degree of TGF-beta1 expression in early biopsy specimens routinely obtained from stable allografts at 100 d could predict fibrosis and graft dysfunction in the late phase. Patients were children with grafts from related donors. We immunohistochemically determined intracellular and extracellular expression of TGF-beta1 in the graft using LC antibody (LC) for intracellular TGF-beta1 and CC antibody (CC) for extracellular TGF-beta1. The change in creatinine clearance between 100 d and 3 yr after transplantation (DeltaCcr) was used as an index of long-term graft function. We also used image analysis to calculate the relative area involved by interstitial fibrosis in the trichrome-stained section of graft biopsy specimens at 100 d and 3 yr, designating the change as DeltaFI. DeltaCcr was -4.2+/-9.4 mL/min in subjects with minimal early immunoreactivity for CC and -20.5+/-15.9 mL/min in subjects with strong reactivity (p0.05). DeltaCcr was -14.5+/-18.6 mL/min in subjects with minimal early immunoreactivity for LC and -11.7+/-12.8 mL/min in those with strong reactivity. DeltaFI in subjects with minimal CC reactivity (1.28+/-4.11%) tended to be lower than that in subjects with strong reactivity (8.45+/-15.47%). Neither fibrosis at 100 d nor DeltaFI differed between subjects with minimal and strong LC reactivity. Thus, strong extracellular TGF-beta1 expression in grafts at 100 d after transplantation is associated with a long-term decline in graft function and tends to be associated with increased graft fibrosis at 3 yr.

The eight mammalian Smad proteins mediate cellular signaling from members of the transforming growth factor-beta (TGF-beta), bone morphogenetic protein (BMP), and activin families. Smads 1, 5, and 8 transmit signals from BMPs, while Smads 2 and 3 transmit signals from TGF-betas and activin. Smad 4 is a common mediator of both pathways, while Smads 6 and 7 inhibit signaling. Signal transduction involves translocation of Smad complexes to the nucleus and subsequent gene activation. Little is known about the expression of endogenous Smad proteins during development. We identified commercially available Smad antibodies that specifically recognize a unique Smad protein and are suitable for immunohistochemistry. Here we compare the localization of Smads 1, 2, 3, 4, 5, and 6 in tissues of the 15-day gestation mouse embryo. Immunoreactive Smad proteins are seen in many tissues with differences in the localization being dependent upon the cell type. All tissues express Smad 4 and at least one each of the BMP-specific and TGF-beta-specific Smads, while expression of Smad 6 is more restricted. Differences are observed in the nuclear versus cytoplasmic localization among the Smads in different cell types or tissues, suggesting selective activation of Smads during this stage of development.

The insulin-like growth factor II receptor (IGFIIR) gene has been identified as a coding region target of microsatellite instability in human gastrointestinal (GI) tumors. IGFIIR normally has two growth-suppressive functions: it binds and stimulates the plasmin-mediated cleavage and activation of the latent transforming growth factor-beta1 (LTGF-beta1) complex, and it mediates the internalization and degradation of IGFII ligand, a mitogen. We used an immunohistochemical approach to determine whether IGFIIR mutation affected expression of these proteins in GI tumors. Four highly specific antibodies were used: LC(1-30), which recognizes the active form of TGF-beta1; anti-LTGF-beta1, which detects the LTGF-beta1 precursor protein; anti-IGFIIR; and anti-IGFII ligand. Twenty GI tumors either with (6 of 20) or without (14 of 20) known IGFIIR mutation were examined, along with matching normal tissues. Results were statistically significant in the following categories: (a) decreased active TGF-beta1 protein expression in IGFIIR-mutant tumor tissues versus matching normal tissues or IGFIIR-wild-type tumor tissues; (b) increased LTGF-beta1 protein expression in IGFIIR-mutant tumor tissues versus matching normal tissues or IGFIIR-wild-type tumor tissues; and (c) increased IGFII ligand protein expression in IGFIIR-mutant tumor tissues versus matching normal tissues or IGFIIR-wild-type tumor tissues. These data suggest that in genetically unstable GI tumors, mutation of a microsatellite within the coding region of IGFIIR functionally inactivates this gene, causing both diminished growth suppression (via decreased activation of TGF-beta1) and augmented growth stimulation (via decreased degradation of the IGFII ligand).

Oxygen-induced pulmonary injury is associated with cell death and a significant inflammatory response. Because transforming growth factor (TGF)-beta is a potent modulator of the immune response, changes in expression of the three TGF-beta (beta 1, beta 2, beta 3) isoforms was determined in lungs of adult mice exposed to > 95% oxygen. TGF-beta 1 immunostaining within cuboidal nonciliated bronchiolar epithelial cells was increased within 3 h of oxygen exposure and continued to increase for 48 h before decreasing to control levels by 72 h. A similar but less marked change that was morphologically consistent with alveolar type II cells was observed in granulated cells. Immunostaining for TGF-beta 2 and TGF-beta 3 revealed a similar change in bronchiolar epithelium with little change observed in the alveolar epithelium. Immunohistochemical changes in TGF-beta expression were not observed in any other pulmonary cells. Northern blot analysis of total lung RNA revealed that expression of the TGF-beta mRNA was not markedly altered over the 72-h exposure period. Exposure to > 95% oxygen resulted in cell type-specific posttranscriptional changes in TGF-beta isoforms in the lung.

Transforming growth factor-beta 1 (TGF-beta 1) is a potent growth inhibitor of epithelial cell growth, but can also stimulate stromal cell growth. Loss of responsiveness to TGF-beta 1 or loss of TGF-beta 1 itself may be important in the progression of cervical intraepithelial neoplasia (CIN) to invasive cervical carcinoma. METHODS. To examine the expression of TGF-beta in early stages of malignant transformation of the uterine cervix, paraffin embedded tissue samples from 11 patients with normal cervical epithelium, 15 with CIN I-III, 12 with microinvasive, and 18 with invasive squamous cell carcinoma were examined using an immunohistochemical technique. Tissues were immunostained with polyclonal antibodies that react with intracellular and extracellular forms of TGF-beta 1.Percent positive staining for the intracellular form of TGF-beta 1 was 100% for normal epithelium, 73.3% for CIN, and 44.1% for invasive carcinomas, (P = 0.002). Percent positive staining for the extracellular form of TGF-beta 1 was 63.6% for stroma underlying normal epithelium, 60% for stroma associated with CIN, and 94.1% for stroma surrounding invasive cancer (P = 0.007).Decreased expression of intracellular TGF-beta 1 in neoplastic epithelium and increased expression of extracellular TGF-beta 1 in stroma associated with invasive cervical carcinoma suggest that an early event in the neoplastic transformation of cervical epithelia] cells may involve the loss of TGF-beta 1. Tumor progression may be indirectly promoted by TGF-beta 1 secreted into or produced by supporting stromal elements.

Although it is recognized that three isoforms of transforming growth factor-beta (TGF-beta) exist in mammals, their expression, distribution, and function in injury and repair are not well characterized. Using immunohistochemistry and antibodies to synthetic peptides of TGF-beta 1, TGF-beta 2, and TGF-beta 3, we determined the distribution of TGF-beta isoforms in lung sections with acute and chronic lesions of idiopathic pulmonary fibrosis (IPF), chronic asbestosis and hypersensitivity pneumonitis, as well as non-specific pneumonitis. In lung sections with advanced pulmonary fibrosis and honeycombing, irrespective of the diagnosis, TGF-beta 1 was prominently expressed in epithelial cells and macrophages and was found to be associated with the extracellular matrix. In lungs with early lesions of IPF and only inflammatory changes, TGF-beta 1 was present in alveolar macrophages but TGF-beta 1 was not present in epithelial cells. Small amounts of matrix-associated TGF-beta 1 were present subepithelially in areas of lung sections from patients with IPF with minimal inflammation and no fibrosis. In normal lungs with no evidence of inflammation or fibrosis TGF-beta 1 was not seen in alveolar macrophages, epithelial cells, or extracellularly. TGF-beta 2 and TGF-beta 3 were expressed in alveolar macrophages, epithelial cells, and smooth muscle cells of vessels and bronchi of normal lungs and lungs with both inflammatory and fibrotic changes. Our findings suggest that while TGF-beta 2 and TGF-beta 3 are ubiquitously expressed in the lung, TGF-beta 1 is expressed in epithelial cells of fibrotic lungs where the presence of TGF-beta 1 is not disease-specific but an indication of the chronicity of the injury.

We have studied the localizations of transforming growth factor-beta (TGF-beta) 2 and 3 immunohistochemically using isoform-specific antibodies and TGF-beta 3 mRNA by in situ hybridization in the nervous system of the 3- to 15-day-old chick embryo with special reference to spinal cord, hindbrain, and dorsal root ganglia (DRG). At embryonic day (E) 3, TGF-beta 3 mRNA as well as TGF-beta 2 and 3 immunoreactivities (IRs) were most prominent in the notochord, wall of the aorta, and dermomyotome. At E5 and E7, strong TGF-beta 2 and 3 IR were seen in or on radial glia of spinal cord and hindbrain. Radial glia in the floor plate region and ventral commissure gave the most intense signal. In the DRG, fiber strands of intense IRs representing extracellular matrix or satellite cells were seen. Neuronal perikarya did not become IR for TGF-beta 2 and 3 until E11, but even then the moderate signals for TGF-beta 3 mRNA could not be specifically localized to the neuronal cell bodies. In E11 and older embryos, spinal cord glial or glial progenitor cells, but not neuronal cell bodies were labeled for TGF-beta 3 mRNA. Immunocytochemistry and western blot analysis indicated that E8 DRG neurons have the TGF-beta receptor type II, and treatment of these cells with NGF induces expression of TGF-beta 3 mRNA. The TGF-beta isoforms 1, 2, and 3 did not promote survival of E8 DRG neurons in dissociated cell cultures. All three TGF-beta isoforms, however, promoted neurite growth from E8 DRG explants, but were less potent than nerve growth factor. Our data suggest identical localizations of TGF-beta 2 and -beta 3 IR in the developing chick and mammalian nervous systems, underscoring the general importance of TGF-beta s in fundamental events of neural development.

We have shown previously that primary prostate cancer demonstrates significant extracellular accumulation of transforming growth factor-beta 1 (TGF-beta 1). To further investigate the potential role of TGF-beta 1 in prostate cancer progression, we evaluated an expanded series of primary prostatic carcinomas and associated lymph node metastases.Prostate tissue samples from 37 patients were examined. Three were organ donors, all less than 30 years of age, whose prostates were included as normal controls. Eighteen had undergone radical prostatectomy and pelvic lymph node dissection. Eleven were without evidence of metastasis, whereas seven were found to have prostate cancer within at least one of their pelvic lymph nodes. Sixteen had undergone transurethral resection of the prostate for benign disease, yet all had prostate cancer within the resected specimen (15 were stage T1b; 1 was stage T1a). Twelve of the patients with stage T1b disease underwent pelvic lymph node dissection and implantation of radioactive gold seeds. All 12 had prostate cancer in at least one lymph node. All specimens were examined for the level of expression and localization of TGF-beta 1 by immunohistochemistry using Ab that distinguish intracellular from extracellular TGF-beta 1.Normal prostate tissue and benign prostatic hyperplasia demonstrated negative or weak intracellular and extracellular staining for TGF-beta 1. By comparison, 29 of 34 primary prostate cancers showed extensive extracellular TGF-beta 1 staining with pronounced intracellular accumulation within epithelial cells in 13 of 34 patients. There was no difference in the staining pattern for extracellular TGF-beta 1 between primary cancers with and without pelvic lymph node metastases. However, in primary cancers without pelvic lymph node metastases, only 1 of 15 patients showed strong intracellular staining for TGF-beta 1 compared with 12 of 19 primary tumors with metastatic disease. In addition, only 2 of 19 lymph node metastases demonstrated weak extracellular TGF-beta 1 staining, but all 19 contained intracellular TGF-beta 1.These findings confirm our previous observation that prostate cancer exhibits enhanced intracellular and extracellular accumulation of TGF-beta 1 relative to normal prostate tissue and benign prostatic hyperplasia. In addition, our study documented a significantly more pronounced accumulation of intracellular TGF-beta 1 in primary prostate cancer with metastasis than in primary tumors without metastasis. Moreover, although the pattern of intracellular TGF-beta 1 staining observed in the primary tumor is maintained in the metastasis, a lack of extracellular accumulation of TGF-beta 1 in the metastatic site was noted. This differential pattern may be biologically important and could conceivably reflect a role for TGF-beta 1 in disease progression.

The distribution of transforming growth factor-beta (TGF-beta) was examined in the posterior segment of the monkey, human, and feline eye using antisera to TGF-beta 1, TGF-beta 2, or TGF-beta 3. A number of different antibodies, tissue processing methods, immunolocalization techniques, and microscopic imaging systems were used in an attempt to gain a more comprehensive picture of TGF-beta isoform distribution in the retina and retinal pigmented epithelium (RPE). The results are generally consistent in identifying one or more of the three TGF-beta isoforms in the cytoplasm of a small, overlapping subset of cells. RPE cells, photoreceptors, Mueller cells, ganglion cells, hyalocytes, and cells associated with choroidal and retinal vessels are all represented in this immunoreactive population. No evidence of extracellular labeling was noted. The intracellular distribution of the three isoforms is distinctly different in photoreceptors. Anti-TGF-beta 1 precursor and anti-TGF-beta 2 immunoreactivity is confined primarily to rod outer segments, whereas anti-TGF-beta 3 immunoreactivities are restricted to mitochondria within inner segments. In the RPE, clusters of anti-TGF-beta 2 positive cytoplasmic granules are located near the cells' lateral borders, whereas anti-TGF-beta 3 labeling is concentrated apically. These results provide baseline information from which new hypotheses regarding the function(s) of TGF-beta isoforms in the retina can be formulated.

Reverse transcription-polymerase chain reaction analysis of total ribonucleic acid (RNA) from human fallopian tubes revealed that transforming growth factor-beta 1 (TGF beta 1), TGF beta 2, and TGF beta 3 as well as TGF beta type I-III messenger RNA (mRNA) are expressed in this tissue. In situ hybridization and immunohistochemical observations using TGF beta isoform-specific [35S]40-mer oligonucleotide probes and polyclonal antibodies indicate that all the tubal cell types express TGF beta isoforms and TGF beta type II receptor mRNA and protein. The tubal epithelial cells appeared to express more TGF beta 1 mRNA and TGF beta 1-3 proteins than other cell types, whereas TGF beta 2 and TGF beta 3 mRNA appeared to be equally expressed in the epithelial and other tubal cell types. In the epithelial lining, both ciliated and nonciliated cells in the ampullary and isthmus regions appeared to express mRNA and protein for TGF beta s and TGF beta type II receptor at a similar level. The intensity of immunostaining of TGF beta s in tubal epithelial cells was lower during the early proliferative and late secretory than the mid- to late proliferative and early to midsecretory phases of the menstrual cycle and reduced during the postmenopausal period. However, the intensity of immunoreactive TGF beta type II receptor in these cells did not vary during the cycle as much as that seen with TGF beta s. Quantitative autoradiography of [125I]TGF beta 1 indicates that fallopian tubes contain specific binding sites for TGF beta 1. Net grain density per 100 microns 2, calculated for different cell types, indicates that the epithelial cells had a significantly higher grain density than other tubal cell types (P < 0.05), with similar densities in the late proliferative and early secretory phases of the cycle. These results provide the first evidence that human fallopian tubes express mRNA and protein and contain specific binding sites for TGF beta system, suggesting an autocrine/paracrine role for TGF beta in a variety of tubal functions.

Increasing evidence suggests that the differential regulation of multiple peptide growth factors by steroid hormones contributes significantly to the pleiotropic effects elicited in target tissues. We report here an evaluation of the effects of the potent estrogen, diethylstilbestrol, on the expression of the three mammalian transforming growth factor beta (TGF beta) isoforms, TGF beta 1, TGF beta 2, and TGF beta 3, in both the uterus and the vagina of the prepubescent mouse. Immunohistochemical protein detection, in situ hybridization, and Northern RNA analyses demonstrate overlapping but distinct time-dependent and site-specific induction of all three TGF beta genes in the reproductive tract in response to estrogen. Temporal analysis of steady-state levels of the TGF beta mRNAs in the uterus by Northern blotting clearly demonstrates that diethylstilbestrol significantly but transiently up-regulates TGF beta 3 mRNA within 30 min and TGF beta 1 and TGF beta 2 mRNAs by 3 h with decreases to/or below control levels by 6 h. The vagina also responds to diethylstilbestrol with similar kinetics of induction for TGF beta 2 and TGF beta 3 mRNAs as that observed in the uterus; however, TGF beta 1 mRNA levels increase gradually and peak around 16 h after treatment. Investigation of the steroid specificity demonstrates predominant estrogen specificity in the control of TGF beta expression in the immature mouse reproductive tract. In situ hybridization localizes the mRNAs for all three TGF beta isoforms, primarily to the uterine and vaginal epithelium. Unlike the transient nature of TGF beta mRNA induction elicited by estrogen, immunohistochemistry demonstrates that estrogen treatment results in a more prolonged elevation of the proteins for TGF beta 1, TGF beta 2, and TGF beta 3 in the epithelium of both tissues. Investigation of specific binding of 125I-TGF beta 1 by affinity labeling reveals the existence of the receptor/binding proteins (types I, II, and III) in the uterus. Estrogen treatment significantly reduces binding to each of these components in the uterus, which suggests that estrogen may modulate TGF beta responsiveness at the receptor level. A comparison of TGF beta mRNA expression to the induction of other estrogen-regulated genes, TGF alpha, insulin-like growth factor-1, c-myc, progesterone receptor and lactotransferrin reveals that, in general, the TGF beta transcript levels are regulated in a more transient manner by estrogen.(ABSTRACT TRUNCATED AT 400 WORDS)

Interactions between the epithelial anlage of the developing mouse inner ear and its associated periotic mesenchyme control the differentiation of the cartilaginous otic capsule. Transforming growth factor-beta1 (TGF-β1) is a naturally occurring signal peptide that is present in these tissues at times of active differentiation and morphogenesis. Previous studies have shown that TGF-β1 alone is not a sufficient stimulus to initiate chondrogenesis in cultured periotic mesenchyme. In this study, we provide evidence that basic fibroblast growth factor (bFGF) can elicit a specific but limited chondrogenic response in cultured periotic mesenchymal cells. We also demonstrate that simultaneous addition of bFGF and TGF-β1 to cultured periotic mesenchyme results in a full chondrogenic response comparable to that which occurs when periotic mesenchyme is grown in the presence of its natural inductor tissue (i.e. otic epithelium). Utilizing antibodies directed against bFGF, we show localization of endogenous bFGF in the otic epithelium in vivo and in mixed epithelial-mesenchymal cultures. Additionally, we demonstrate the presence of FGF-like activity in medium conditioned by otic epithelium. Blocking of epithelial elicited chondrogenesis by a combination of both αbFGF and αTGF-β1 antibodies provides further evidence of the necessity for these growth factors in the chondrogenic differentiation of periotic mesenchyme in vitro. Our results suggest a role for both bFGF and TGF-β1 in the regulation of chondrogenesis during otic capsule formation in situ.

Transgenic model systems provide tools for obtaining information that clarifies important relationships between genetic alterations and carcinogenesis. One such relationship is the induction of specific growth factor activities by dominantly acting oncogenes. Using a "transgenic organ" model referred to as mouse prostate reconstitution (MPR) under conditions where the ras and myc oncogenes were introduced using a recombinant retrovirus into both the mesenchymal and epithelial compartments of the urogenital sinus, poorly differentiated prostate cancer (PC) was produced with high frequency (90%) in inbred C57BL/6 mice. Time-course studies using northern blotting and immunohistochemical analysis showed that the transition from benign to malignant status invariably was associated with the induction of elevated transforming growth factor-beta 1 (TGF-beta 1) expression. Additional immunohistochemical analysis of TGF-beta 1 in human PC and benign prostatic hyperplasia (BPH) showed that positive extracellular staining was significantly more extensive in PC compared with BPH. This differential staining pattern was evident in focal areas of PC adjacent to BPH. These findings in both the MPR model system and human PC suggest that elevated TGF-beta 1 expression is involved in the progression to malignancy and that its pattern of expression may become a useful marker of PC. Additional studies using transgenic animal models will continue to provide important clinically useful information about PC in man.

The implantation process involves complex interactions between embryonic and uterine cells. The major events of the implantation process are (i) synchronized development of the preimplantation embryo into a blastocyst and establishment of the receptive uterus (1); (ii) escape of the embryo from immunological responses of the mother (2); (iii) increased endometrial capillary permeability at the site of the blastocyst apposition (1); (iv) localized decidualization of the endometrial stroma following blastocyst attachment (1,3); and (v) controlled uterine invasion by trophoblasts (4). These events are a conglomerate of temporally and spatially regulated proliferation, differentiation, migration, and remodeling of heterogeneous cell types of both the embryonic and uterine tissues.

Suppression of rejection of the conceptus is a thesis arising from the paradigm that the fetus resulting from mating of genetically dissimilar individuals is an allograft that paradoxically is highly successful. Cells able to suppress the generation of cytotoxic T lymphocytes (CTL) against paternal Class I MHC were found in paraaortic lymph nodes draining the uterus in most strains of allogeneically mated mice and, where deficient (i.e., C57B110ScSn, CBA/J), were detectable in the decidua (Clark 1991). Deficient decidual suppressor cell activity was found in mice with a high rate of spontaneous resorption (Clark et al 1986, 1990a, 1991a). It is important to note that kinetic studies of suppressor cell activity in decidua during mouse pregnancy demonstrated two types of suppressor cells, a CD8+ T cell population present during the pre- and peri-implantation phase of pregnancy, and a non-T non-B cell population which developed 4–5 days after implantation (Clark et al 1991b). Both were antigen non-specific, and the latter non-T non-B suppressor cell was particularly interesting as it released a soluble suppressor factor closely related to TGF-β2, and developed just before the usual time of onset of abortion in mice (Clark et al 1990b, 1991b, Lea et al 1992).

We have investigated the ability of tamoxifen to regulate members of the transforming growth factor beta (TGF-beta) family in human breast cancers in vivo. Using immunohistochemical techniques, we find that 3 months of tamoxifen treatment causes a consistent induction of extracellular TGF-beta 1 in breast cancer biopsies, compared with matched pretreatment samples from the same patient. The induced TGF-beta is localized between and around stromal fibroblasts and appears to be derived from these cells. Lower levels of TGF-beta 1,-beta 2, and -beta 3 seen in epithelial cells were not altered by tamoxifen treatment. The increased stromal staining of TGF-beta 1 occurred in estrogen receptor-negative as well as estrogen receptor-positive tumors. These results provide in vivo evidence for a novel, estrogen receptor-independent mechanism of action for tamoxifen, involving the stromal induction of a potent growth inhibitor for epithelial cells.

Transforming growth factor beta (TGF beta) is a multifunctional protein which has been suggested to play a central role in the pathogenesis of chronic inflammation and fibrosis. Nasal polyposis is a condition affecting the upper airways characterized by the presence of chronic inflammation and varying degrees of fibrosis. To examine the potential role of TGF beta in the pathogenesis of this condition, we investigated gene expression and cytokine production in nasal polyp tissues as well as in the normal nasal mucosa. By Northern blot analysis using a porcine TGF beta 1 cDNA probe, we detected TGF beta 1-specific mRNA in nasal polyp tissues, as well as in the tissue from a patient with allergic rhinitis, but not in the normal nasal mucosa. By the combination of tissue section staining with chromotrope 2R with in situ hybridization using the same TGF beta 1 probe, we found that approximately 50% of the eosinophils infiltrating the polyp tissue express the TGF beta 1 gene. In addition, immunohistochemical localization of TGF beta 1 was detected associated with extracellular matrix as well as in cells in the stroma. These results suggest that in nasal polyposis where eosinophils are the most prevalent inflammatory cell, TGF beta 1 synthesized by these cells may contribute to the structural abnormalities such as stromal fibrosis and basement membrane thickening which characterize this disease.

Transforming growth factor-beta 1 (TGF-beta 1) is a multifunctional cytokine with immunosuppressive effects on T cells in vitro. Experimental allergic encephalomyelitis is an archetypal T cell-mediated autoimmune demyelinating disease of the central nervous system that often serves as a model for multiple sclerosis. In vivo administration of TGF-beta 1 into SJL mice was successful in reducing the incidence of clinical disease and the histologic severity of inflammation and demyelination in the brain and spinal cord. Immunohistochemical studies performed on control animals showed that TGF-beta-1, -2, and -3 were present in inflammatory perivascular lesions in the brain. The use of a naturally occurring cytokine with immunoregulatory functions in the treatment of an autoimmune disease is novel. However, potential long term complications of such therapy must be addressed before its use in human autoimmune disease such as multiple sclerosis.

In this study transforming growth factor-beta 1 (TGF-beta 1) has been immunolocalized in developing rat molars using two well characterized polyclonal antibodies, Anti-CC and Anti-LC, that recognize extracellular and intracellular TGF-beta 1, respectively. With immunohistochemical methods and the ABC-peroxidase system of detection, the growth factor was immunolocalized within the ectodermally derived enamel organ and the neural crest-derived dental papilla at the early and advanced bell stages of development. With Anti-CC, widespread and abundant extracellular TGF-beta 1 was found associated with the stellate reticulum and within central and apical regions of dental papilla mesenchyme. In contrast, Anti-LC localized TGF-beta 1 intensely within the cells of the outer dental epithelium. Moderate immunostaining for TGF-beta 1 with Anti-LC was also evident within the apical cytoplasm of inner dental epithelial cells and odontoblasts. These findings support the hypothesis that TGF-beta 1 may play a paracrine role in tooth development by regulating the epithelial-mesenchymal interactions that influence growth and cytodifferentiation events.

Non-T small lymphocytic suppressor cells in murine allopregnancy release a potent immunosuppressive factor in vitro that is neutralized by rabbit anti-transforming growth factor (TGF)-beta. Previous studies have suggested that the decidual suppressor factor (DSF) is smaller than TGF-beta 1, and in this paper, we show that DSF on HPLC-sieving columns also elutes later than TGF-beta 2. Nevertheless, DSF has the ability to promote anchorage-independent growth of NRK fibroblasts similar to TGF-beta s. Using turkey antibodies specific for TGF-beta 1 or beta 2, we show that DSF is related to TGF-beta 2 rather than TGF-beta 1, and this relationship was confirmed by using a panel of murine mAb to TGF-subtypes. PAGE and Western blotting showed that the TGF-beta 2-reactive molecules in HPLC-purified DSF was slightly smaller than TGF-beta 2 and approximately 20 to 23 kDa. The DSF molecule is therefore closely related to TGF-beta 2 but as released from decidua, differs in size. The TGF-beta 2-related decidual suppressor factor was also obtained from the decidua of synpregnant C.B.-17 severe combined immune deficiency (SCID) and pregnant SCID-BG (C57BL/6 background) mice, confirming the lack of T or B cell dependence of DSF production and the generality of production of a TGF-beta-related suppressor factor by decidua associated with successful pregnancy in mice.

We report here that extracellular TGF-beta 1 is associated exclusively with microfibrils of elastin which are present in the extracellular matrix of the inflamed articular joint of the rat. Inflammation was initiated by bacterial cell walls localized in the synovium following intraperitoneal injection of the bacterial components. This synovitis is associated with both destruction of connective tissue components and matrix deposition. The growth factor was localized by using a polyclonal antibody raised to a synthetic peptide corresponding to amino terminal 30 amino acids of TGF-beta 1 in conjunction with a gold-labeled secondary antibody. The results suggest a close association of TGF-beta 1 with proteoglycans which are known to be a major component of the microfibrils in elastin. Proteoglycan-mediated binding and concentration of TGF-beta 1 in specific areas of the extracellular matrix may constitute a mechanism whereby the growth factor could be targeted to specific sites of action.

The growth of synovial fibroblast-like cells from patients with rheumatoid arthritis and rats with streptococcal cell wall (SCW)-induced arthritis in vitro under anchorage-independent conditions is inhibited by transforming growth factor-beta (TGF-beta). Because this growth factor is present in rheumatoid synovial fluids, we studied whether this cytokine might be secreted by cells in rheumatoid synovial tissue. We show that synovial tissues from patients with rheumatoid arthritis and osteoarthritis, and rats with SCW-induced arthritis, contain TGF-beta-1 mRNA. TGF-beta, predominantly type 1, was spontaneously secreted in vitro by synovial tissue explants and synovial fibroblast-like cells. In addition, TGF-beta could be detected immunohistochemically in cells throughout rheumatoid and SCW-induced arthritic rat synovial tissues. Finally, exogenous TGF-beta induced collagen and inhibited collagenase mRNA levels by cultured synoviocytes. These data support an autocrine role for TGF-beta in the regulation of synoviocytes in rheumatoid arthritis and, in light of its demonstrated effects on the immune system, suggest that TGF-beta might also have important paracrine effects on infiltrating inflammatory cells.

Semisynthetic N epsilon- acetimidoglucagon was prepared from the [des- His1 ]analogue by coupling the N-hydroxysuccinimide ester of N alpha- tBoc - Nimidazole -DNP-L-histidine to the peptide in dimethylformamide in the presence of 1-hydroxybenzotriazole. The deprotected, purified product was chemically identical to N epsilon- acetimidoglucagon and equipotent to N epsilon- acetimidoglucagon and native glucagon in its ability to activate adenylate cyclase and displace [125I] iodoglucagon from rat liver plasma membranes. Semisynthetic [ Phe1 ]-, [ Ala1 ]-, and [des- His1 ] glucagons prepared similarly achieved 85, 55, and 35% of the maximal activity and 22, 2, and 6% of the binding potency of N epsilon- acetimidoglucagon . The biological assays indicate that the amino group is involved to a greater extent in transduction than in binding, but the aromatic nature and hydrogen bonding capability of the imidazole ring of histidine-1 are important for both binding and transduction. In circular dichroism studies, all derivatives exhibited increased helicity in 2-chloroethanol. The [ Phe1 ] analogue although less soluble behaved similarly to native glucagon, while the [ Ala1 ] and [des- His1 ] derivatives exhibited an increased helical content in 0.01 N HCl as a result of an increased propensity of these derivatives to self-associate in the absence of 2-chloroethanol. The unexpected conformational changes throughout the molecule may have relevance for the functional activity.

Transforming growth factors-alpha and beta (TGF-alpha and -beta) and platelet-derived growth factor (PDGF), three distinct peptide hormones, acting together, are able to potentiate the phenotypic transformation of normal rat kidney (NRK) cells. Cells transformed by retroviruses have been shown to secrete increased levels of TGF-alpha, TGF-beta and PDGF. We report here that Harvey sarcoma virus-transformed NIH-3T3 cells and Moloney sarcoma virus-transformed NRK cells show increased expression of the mRNAs for TGF-alpha, TGF-beta, PDGF A-chain and nerve growth factor (NGF) compared to their untransformed counterparts. No amplification or rearrangement in the genomic DNA is seen in the transformed cells. In tumor tissue formed by subcutaneous injection of Ha-3T3 cells, this enhanced level of TGF-beta mRNA returns to the control level of the untransformed cells. The increase in TGF-beta mRNA in the transformed cells is paralleled by an increase in the level of TGF-beta protein as shown by immunoprecipitation and Western blotting procedures using specific TGF-beta antibodies.

Human platelets, when induced to degranulate by thrombin, secrete transforming growth factor-beta (TGF-beta) in a biologically latent form. In this form, TGF-beta cannot bind to its cellular receptor, nor can it be immunoprecipitated by polyclonal antisera to TGF-beta, suggesting that the receptor-binding site and other TGF-beta epitopes may be masked. Western blot analysis of the platelet secretate indicates that the latent form of TGF-beta is a 220-235 kDa complex, in which mature TGF-beta (25 kDa) is noncovalently associated with sequences from the remainder of the precursor (74 kDa), and a third unidentified entity (approximately 135 kDa). The third component is immunologically unrelated to other growth factor binding proteins. The complex is glycosylated, and gel filtration analysis suggests it may exist in solution as higher molecular weight aggregates. Further chromatographic analysis indicates that in its latent form, the platelet TGF-beta cannot bind to alpha 2-macroglobulin (alpha 2M), but that if the platelet latent TGF-beta is activated by transient acidification, the released active TGF-beta will bind to alpha 2M. We have previously identified the latent form of TGF-beta found in serum as an alpha 2M.TGF-beta complex (O'Connor-McCourt, M. D., and Wakefield, L. M. (1987) J. Biol. Chem. 262, 14090-14099). We now propose that the latent TGF-beta secreted by platelets may be a cellular delivery complex, whereas the latent form found in serum may represent a clearance complex. Thus alpha 2M may scavenge excess TGF-beta that is released when the platelet latent form is activated, possibly by the clotting process. Finally, we have shown that the latent form of TGF-beta secreted by a variety of cell types in culture is similar, if not identical to that secreted by platelets.

Semisynthetic N epsilon- acetimidoglucagon was prepared from the [des- His1 ]analogue by coupling the N-hydroxysuccinimide ester of N alpha- tBoc - Nimidazole -DNP-L-histidine to the peptide in dimethylformamide in the presence of 1-hydroxybenzotriazole. The deprotected, purified product was chemically identical to N epsilon- acetimidoglucagon and equipotent to N epsilon- acetimidoglucagon and native glucagon in its ability to activate adenylate cyclase and displace [125I] iodoglucagon from rat liver plasma membranes. Semisynthetic [ Phe1 ]-, [ Ala1 ]-, and [des- His1 ] glucagons prepared similarly achieved 85, 55, and 35% of the maximal activity and 22, 2, and 6% of the binding potency of N epsilon- acetimidoglucagon . The biological assays indicate that the amino group is involved to a greater extent in transduction than in binding, but the aromatic nature and hydrogen bonding capability of the imidazole ring of histidine-1 are important for both binding and transduction. In circular dichroism studies, all derivatives exhibited increased helicity in 2-chloroethanol. The [ Phe1 ] analogue although less soluble behaved similarly to native glucagon, while the [ Ala1 ] and [des- His1 ] derivatives exhibited an increased helical content in 0.01 N HCl as a result of an increased propensity of these derivatives to self-associate in the absence of 2-chloroethanol. The unexpected conformational changes throughout the molecule may have relevance for the functional activity.

The growth of synovial fibroblast-like cells from patients with rheumatoid arthritis and rats with streptococcal cell wall (SCW)-induced arthritis in vitro under anchorage-independent conditions is inhibited by transforming growth factor-beta (TGF-beta). Because this growth factor is present in rheumatoid synovial fluids, we studied whether this cytokine might be secreted by cells in rheumatoid synovial tissue. We show that synovial tissues from patients with rheumatoid arthritis and osteoarthritis, and rats with SCW-induced arthritis, contain TGF-beta-1 mRNA. TGF-beta, predominantly type 1, was spontaneously secreted in vitro by synovial tissue explants and synovial fibroblast-like cells. In addition, TGF-beta could be detected immunohistochemically in cells throughout rheumatoid and SCW-induced arthritic rat synovial tissues. Finally, exogenous TGF-beta induced collagen and inhibited collagenase mRNA levels by cultured synoviocytes. These data support an autocrine role for TGF-beta in the regulation of synoviocytes in rheumatoid arthritis and, in light of its demonstrated effects on the immune system, suggest that TGF-beta might also have important paracrine effects on infiltrating inflammatory cells.

Transforming growth factor beta 1 (TGF-beta 1) regulates the growth, differentiation, or function of nearly all cell types. We now report that TGF-beta 1 increases steady-state levels of its own message in six different normal and transformed cells in culture. Accumulation of TGF-beta 1 mRNA can be detected by Northern blot analysis within 3 h of addition of the peptide to cells, and enhanced message levels persist as long as TGF-beta 1 is present in the culture medium. This autoinduction is half-maximal at approximately 10 PM TGF-beta 1, and maximal stimulation corresponds to a 2-3-fold increase in transcript levels. In normal rat kidney cells, the rise in TGF-beta 1 mRNA is actinomycin D-sensitive and is accompanied by a parallel (approximately 3-fold) increase in secretion of TGF-beta 1 protein in the culture medium of treated cells, as detected by immunoprecipitation of biosynthetically labeled 35S-labeled TGF-beta 1 using specific anti-TGF-beta 1 antibodies. Treatment of normal rat kidney cells with either epidermal growth factor or platelet-derived growth factor also results in an increase in TGF-beta 1 mRNA (2-3-fold), although epidermal growth factor and TGF-beta 1 appear to act via distinct mechanisms since their combined effects are greater than additive.

Transforming growth factor-beta (TGF-beta) is now known to have a number of actions in addition to the induction of phenotypic transformation in fibroblastic cells. In this paper, we characterize its inhibition of differentiation in rat myoblasts of Yaffe's L6 strain and demonstrate its identity or very close similarity to the differentiation inhibitor (DI) secreted by Buffalo rat liver cells cultured in serum-free medium. At concentrations as low as 60 pg/ml, TGF-beta gave detectable inhibition of differentiation measured as myoblast fusion and creatine kinase elevation; maximal inhibition was observed at and above 0.5 ng/ml (20 pM). The inhibition persisted as long as fresh TGF-beta was added at 48-h intervals, but it was reversed upon removal of the factor. By itself or in the presence of mitogens, TGF-beta had no mitogenic activity in the L6 cells. Concentration dependencies of human TGF-beta and the rat DI were closely parallel in three assays: inhibition of myoblast differentiation, stimulation of normal rat kidney cell growth in soft agar, and competition for displacement of labeled TGF-beta from binding sites on A549 human lung carcinoma cells. We conclude that most if not all of the DI activity found in medium conditioned by Buffalo rat liver cells can be attributed to the presence of TGF-beta or a very similar molecule. These observations also offer a potentially useful approach to study the control of myogenesis; the process(es) can be blocked in cloned L6 myoblasts by incubation with very small quantities of a pure protein in fully defined serum-free medium.