Inhibition Of TGF-β Activity Research Articles

Disruption of TGF-β signaling pathway is required to mediate effective killing of hepatocellular carcinoma by human iPSC-derived NK cells.

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer. Transforming growth factor beta (TGF-β) is highly expressed in the liver tumor microenvironment and is known to inhibit immune cell activity. Here, we used human induced pluripotent stem cells (iPSCs) to produce natural killer (NK) cells engineered to mediate improved anti-HCC activity. Specifically, we produced iPSC-NK cells with either knockout TGF-β receptor 2 (TGFBR2-KO) or expression of a dominant negative (DN) form of the TGF-β receptor 2 (TGFBR2-DN) combined with chimeric antigen receptors (CARs) that target either GPC3 or AFP. The TGFBR2-KO and TGFBR2-DN iPSC-NK cells are resistant to TGF-β inhibition and improved anti-HCC activity. However, expression of anti-HCC CARs on iPSC-NK cells did not lead to effective anti-HCC activity unless there was also inhibition of TGF-β activity. Our findings demonstrate that TGF-β signaling blockade is required for effective NK cell function against HCC and potentially other malignancies that express high levels of TGF-β.

Disruption of TGF-β signaling pathway is required to mediate effective killing of hepatocellular carcinoma by human iPSC-derived NK cells.

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer. Transforming growth factor beta (TGF-β) is highly expressed in the liver tumor microenvironment and is known to inhibit immune cell activity. Here, we used human induced pluripotent stem cells (iPSCs) to produce natural killer (NK) cells engineered to mediate improved anti-HCC activity. Specifically, we produced iPSC-NK cells with either knockout TGF-β receptor 2 (TGFBR2-KO) or expression of a dominant negative (DN) form of the TGF-β receptor 2 (TGFBR2-DN) combined with chimeric antigen receptors (CARs) that target either GPC3 or AFP. The TGFBR2-KO and TGFBR2-DN iPSC-NK cells are resistant to TGF-β inhibition and improved anti-HCC activity. However, expression of anti-HCC CARs on iPSC-NK cells did not lead to effective anti-HCC activity unless there was also inhibition of TGF-β activity. Our findings demonstrate that TGF-β signaling blockade is required for effective NK cell function against HCC and potentially other malignancies that express high levels of TGF-β.

TNF-α and IL-1β Do Not Induce Langerhans Cell Migration by Inhibiting TGFβ Activation

In the skin, Langerhans cells (LCs) require autocrine latent TGFβ that is transactivated by the integrins ανβ6 and ανβ8 expressed by keratinocytes (KCs) for long-term epidermal retention. Selective expression of a ligand-independent, constitutively active form of TGFβR1 inhibits LC migration during homeostasis and in response to UVB exposure. In this study, we found that LC migration in response to inflammatory stimuli was also inhibited by ligand-independent TGFβR1 signaling. Contrary to UVB stimulation, which reduced KC expression of ανβ6, in vitro and in vivo exposure to TNF-α or IL-1β increased ανβ6 transcript and protein expression by KCs. This resulted in increased KC-mediated transactivation of latent TGFβ. Expression of ανβ8 was largely unchanged. These findings show that ligand-independent TGFβR1 signaling in LCs can overcome inflammatory migration stimuli, but reduced KC-mediated transactivation of latent TGFβ by KCs may only drive LC migration during homeostasis and in response to UV stimulation.

Therapeutic targeting of TGF-β in cancer: hacking a master switch of immune suppression.

Cancers may escape elimination by the host immune system by rewiring the tumour microenvironment towards an immune suppressive state. Transforming growth factor-β (TGF-β) is a secreted multifunctional cytokine that strongly regulates the activity of immune cells while, in parallel, can promote malignant features such as cancer cell invasion and migration, angiogenesis, and the emergence of cancer-associated fibroblasts. TGF-β is abundantly expressed in cancers and, most often, its abundance associated with poor clinical outcomes. Immunotherapeutic strategies, particularly T cell checkpoint blockade therapies, so far, only produce clinical benefit in a minority of cancer patients. The inhibition of TGF-β activity is a promising approach to increase the efficacy of T cell checkpoint blockade therapies. In this review, we briefly outline the immunoregulatory functions of TGF-β in physiological and malignant contexts. We then deliberate on how the therapeutic targeting of TGF-β may lead to a broadened applicability and success of state-of-the-art immunotherapies.

Transforming growth factor β in breast cancer: another new trick for the old dog.

Two recent papers from the laboratory of Professor Ming Li demonstrate that inhibition of transforming growth factor β specifically in CD4+ T cells can suppress tumor growth through an unanticipated mechanism.

Abstract 4090: Defeating primary checkpoint resistance: SRTβ1-Ab3 is a first-in-class, fully human antibody that renders resistant tumors sensitive to anti-PD-1

Abstract Despite the clinical breakthroughs achieved by checkpoint blockade therapy (CBT), a majority of patients treated with PD-(L)1 inhibitors fail to respond due to primary or acquired resistance. TGFβ signaling has recently been implicated as a mechanism of primary resistance to CBT, very likely via mechanisms that include immune exclusion. However, therapeutic targeting of the TGFβ pathway has been hindered by dose-limiting cardiotoxicities, most likely due to inhibition of signaling from multiple TGFβ isoforms. Upon secretion, TGFβ growth factor is held dormant in a latent complex with its non-covalently associated prodomain. TGFβ activation is triggered by extracellular events, such as integrin binding or proteolytic cleavage, that release the growth factor from this latent complex. We have demonstrated that isoform-specific inhibition of TGFβ activation can be achieved by targeting the prodomain to stabilize the latent TGFβ complex. We recently identified TGFβ1 as the predominant isoform in many human cancers, especially those for which CBT is approved for therapeutic intervention. SRTβ1-Ab3 is a fully-human antibody against latent TGFβ1 that inhibits its activation without binding or inhibiting latent TGFβ2, latent TGFβ3, or the active TGFβ1 growth factor. In syngeneic tumor models of primary CBT resistance, pharmacologic blockade of TGFβ1 activation with SRTβ1-Ab3 is sufficient to sensitize TGFβ1-predominant tumors to PD-1 inhibition. Mechanistically, combination treatment with anti-PD-1/SRTβ1-Ab3 overcomes immune exclusion in these models, induces CD8+ T cell infiltration into the tumors, and results in a reduction of myeloid immunosuppressive cells. In contrast, monotherapy with either anti-PD-1 or SRTβ1-Ab3 alone has only modest effects on these cell populations. Gene expression profiling of single vs. combination treated tumor samples provides a molecular view of effects on signaling pathways, cell populations, and activation status of these cells. These data demonstrate the efficacy of TGFβ1-specific inhibition in combination with anti-PD-1 in multiple mouse models of primary checkpoint resistance. Taken together, these synergistic effects at the tumor, cellular, and molecular levels, the preclinical safety profile, and the pharmacokinetic properties of SRTβ1-Ab3 establish a strong rationale for advancing the development of SRTβ1-Ab3 toward clinical application in cancer immunotherapy. Citation Format: Thomas Schürpf, Constance J. Martin, Christopher Littlefield, Christopher Chapron, Stefan Wawersik, Ashish Kalra, Allison Simpson, Francis Danehy, Christopher Boston, Anastasia Nikiforov, Susan Lin, Justin Jackson, Gregory J. Carven, Alan Buckler, Abhishek Datta. Defeating primary checkpoint resistance: SRTβ1-Ab3 is a first-in-class, fully human antibody that renders resistant tumors sensitive to anti-PD-1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4090.

Recombinant growth differentiation factor 11 impairs fracture healing through inhibiting chondrocyte differentiation.

Growth differentiation factor 11 (GDF11), a secreted member of the transforming growth factor-β (TGF-β) superfamily, has been reported to have the capacity to reverse age-related pathologic changes and regulate organ regeneration after injury; however, the role of GDF11 in fracture healing and bone repair is still unclear. Here, we established a fracture model in 12-week-old male mice to observe two healing states: the cartilaginous callus and bony callus formation phases. Our results showed that recombinant GDF11 (rGDF11) injection inhibits cartilaginous callus maturation and hard callus formation, thereby impairing fracture healing in vivo. In vitro, rGDF11 administration inhibited chondrocyte differentiation and maturation by phosphorylating SMAD2/3 protein and inhibiting RUNX2 expression. Notably, inhibition of TGF-β activity by a SMAD-specific inhibitor attenuated GDF11 effects. Thus, our study demonstrates that, rather than acting as a rejuvenating agent, rGDF11 impairs fracture healing by inhibiting chondrocyte differentiation and maturation.

Decorin counteracts disease progression in mice with recessive dystrophic epidermolysis bullosa

Loss-of-function mutations in the gene encoding type VII collagen underlie recessive dystrophic epidermolysis bullosa (RDEB), a disease characterized by skin and mucosal blistering, impaired wound healing, and diffuse dermal inflammation and fibrosis. Transforming growth factor-β signaling plays a crucial role in determining RDEB fibrotic microenvironment that leads to the development of disabling secondary disease manifestations, including hand and foot deformities. Experimental findings indicate that expression levels of decorin, a small leucine-rich proteoglycan and an endogenous TGF-β inhibitor, can modulate RDEB disease phenotype by contrasting dermal fibroblast fibrotic behavior. In this study, the ability of decorin to modify RDEB course was investigated by systemically treating RDEB mice with a lentivirus expressing human decorin. Overexpressed decorin was able to enhance survival, and to limit digit contraction and the development of paw deformities. These effects were associated with decreased TGF-β1 levels and TGF-β signaling activation. Fibrotic traits were strongly reduced in paw skin and also attenuated in the non-chronically injured back skin. However, the expression of pro-inflammatory proteins was not decreased in both paw and back skin. Our findings confirm TGF-β role in promoting fibrosis and disease progression in RDEB, and show that decorin counteracts disease manifestations by inhibiting TGF-β activation. More generally, our data indicate that modifying extracellular matrix composition is an option to improve RDEB disease course.

Vitamin D inhibits the epithelial-mesenchymal transition by a negative feedback regulation of TGF-β activity

Vitamin D and TGF-β exert opposite effects on epithelial-mesenchymal EMT transition. Here we report a novel mechanism of action of TGF-β that promotes the counteracting activity of vitamin D; in two models of human epithelial-mesenchymal EMT transition we demonstrated for the first time that TGF-β strongly induced the expression of vitamin D receptor (VDR) and that 1,25(OH)2D3 was able to contrast the TGF-β-driven EMT transition by transcriptional modulation. In human bronchial epithelial cells the effects of TGF-β on EMT transition markers (E-Cadherin expression and cell motility) were reversed by pre-treatment and co-treatment with 1,25(OH)2D3, but not when the hormone was given later. Silencing experiments demonstrated that the inhibition of TGF-β activity was VDR-dependent. 1,25(OH)2D3 abrogated the mitochondrial stimulation triggered by TGF-β. In fact we showed that 1,25(OH)2D3 repressed the transcriptional induction of respiratory complex, limited the enhanced mitochondrial membrane potential and restrained the increased levels of mitochondrial ATP; 1,25(OH)2D3 also decreased the production of reactive oxygen species promoted by TGF-β. Overall, our study suggests that the overexpression and activity of VDR may be a regulatory response to TGF-β signaling that could be exploited in clinical protocols, unraveling the therapeutic potentiality of 1,25(OH)2D3 in the prevention of cancer metastasis.

The Lactate Dehydrogenase Inhibitor Gossypol Inhibits Radiation-Induced Pulmonary Fibrosis.

Exposure of the lung to ionizing radiation that occurs in radiotherapy, as well as after accidental or intentional mass casualty incident can result in pulmonary fibrosis, which has few treatment options. Pulmonary fibrosis is characterized by an accumulation of extracellular matrix proteins that create scar tissue. Although the mechanisms leading to radiation-induced pulmonary fibrosis remain poorly understood, one frequent observation is the activation of the profibrotic cytokine transforming growth factor-beta (TGF-β). Our laboratory has shown that the metabolite lactate activates latent TGF-β by a reduction in extracellular pH. We recently demonstrated that lactate dehydrogenase-A (LDHA), the enzyme that produces lactate, is upregulated in patients with radiation-induced pulmonary fibrosis. Furthermore, genetic silencing of LDHA or pharmacologic inhibition using the LDHA inhibitor gossypol prevented radiation-induced extracellular matrix secretion in vitro through inhibition of TGF-β activation. In the current study, we hypothesized that LDHA inhibition in vivo prevents radiation-induced pulmonary fibrosis. To test this hypothesis, C57BL/6 mice received 5 Gy total-body irradiation plus 10 Gy thoracic irradiation from a 137Cs source to induce pulmonary fibrosis. Starting at 4 weeks postirradiation, mice were treated with 5 mg/kg of the LDHA inhibitor gossypol or vehicle daily until sacrifice at 26 weeks postirradiation. Exposure to radiation resulted in pulmonary fibrosis, characterized by an increase in collagen content, fibrosis area, extracellular matrix gene expression and TGF-β activation. Irradiated mice treated with gossypol had significantly reduced fibrosis outcomes, including reduced collagen content in the lungs, reduced expression of active TGF-β, LDHA and the transcription factor hypoxia-inducible factor-1 alpha (HIF-1α). These findings suggest that inhibition of LDHA protects against radiation-induced pulmonary fibrosis, and may be a novel therapeutic strategy for radiation-induced pulmonary fibrosis.

F-spondin negatively regulates dental follicle differentiation through the inhibition of TGF-β activity

ObjectiveF-spondin is an extracellular matrix (ECM) protein that belongs to the thrombospondin type I repeat superfamily and is a negative regulator of bone mass. We have previously shown that f-spondin is specifically expressed in the dental follicle (DF), which gives rise to the periodontal ligament (PDL) during the tooth root formation stage. To investigate the molecular mechanism of PDL formation, we investigated the function of f-spondin in DF differentiation. DesignThe expression patterning of f-spondin in the developing tooth germ was compared with that of periodontal ligament-related genes, including runx2, type I collagen and periostin, by in situ hybridization analysis. To investigate the function of f-spondin during periodontal ligament formation, an f-spondin adenovirus was infected into the bell stage of the developing tooth germ, and the effect on dental differentiation was analyzed. ResultsF-spondin was specifically expressed in the DF of the developing tooth germ; by contrast, type I collagen, runx2 and periostin were expressed in the DF and in the alveolar bone. F-spondin-overexpresssing tooth germ exhibited a reduction in gene expression of periostin and type I collagen in the DF. By contrast, the knockdown of f-spondin in primary DF cells increased the expression of these genes. Treatment with recombinant f-spondin protein functionally inhibited periostin expression induced by transforming growth factor-β (TGF-β). ConclusionOur data indicated that f-spondin inhibits the differentiation of DF cells into periodontal ligament cells by inhibiting TGF-β. These data suggested that f-spondin negatively regulates PDL differentiation which may play an important role in the immature phenotype of DF.

Halofuginone attenuates osteoarthritis by inhibition of TGF-β activity and H-type vessel formation in subchondral bone

ObjectivesExamine whether osteoarthritis (OA) progression can be delayed by halofuginone in anterior cruciate ligament transection (ACLT) rodent models.Methods3-month-old male C57BL/6J (wild type; WT) mice and Lewis rats were randomised to...

Selective targeting of TGF-β activation to treat fibroinflammatory airway disease.

Airway remodeling, caused by inflammation and fibrosis, is a major component of chronic obstructive pulmonary disease (COPD) and currently has no effective treatment. Transforming growth factor-β (TGF-β) has been widely implicated in the pathogenesis of airway remodeling in COPD. TGF-β is expressed in a latent form that requires activation. The integrin αvβ8 (encoded by the itgb8 gene) is a receptor for latent TGF-β and is essential for its activation. Expression of integrin αvβ8 is increased in airway fibroblasts in COPD and thus is an attractive therapeutic target for the treatment of airway remodeling in COPD. We demonstrate that an engineered optimized antibody to human αvβ8 (B5) inhibited TGF-β activation in transgenic mice expressing only human and not mouse ITGB8. The B5 engineered antibody blocked fibroinflammatory responses induced by tobacco smoke, cytokines, and allergens by inhibiting TGF-β activation. To clarify the mechanism of action of B5, we used hydrodynamic, mutational, and electron microscopic methods to demonstrate that αvβ8 predominantly adopts a constitutively active, extended-closed headpiece conformation. Epitope mapping and functional characterization of B5 revealed an allosteric mechanism of action due to locking-in of a low-affinity αvβ8 conformation. Collectively, these data demonstrate a new model for integrin function and present a strategy to selectively target the TGF-β pathway to treat fibroinflammatory airway diseases.

Vascular Endothelial Growth Factor Receptor Inhibitor SU5416 Suppresses Lymphocyte Generation and Immune Responses in Mice by Increasing Plasma Corticosterone

Inhibitors of vascular endothelial growth factor and its receptors (VEGFRs) are attractive therapeutic candidates for cancer treatment. One such small molecule VEGFR inhibitor, SU5416, limits angiogenesis in vivo and is widely used for investigating VEGFR signaling in tumor pathophysiology. Herein, we describe novel actions of SU5416 on the immune system. Treatment of mice with SU5416 for 3 days induced significant reductions in size and cellularity of peripheral lymph nodes. Interestingly, SU5416 did not affect initial lymphocyte localization to peripheral lymph nodes but did reduce lymphocyte accumulation during long-term migration assays. Treatment with SU5416 also induced severe loss of double-positive thymocytes resulting in thymic atrophy and a reduction in peripheral B cells. Furthermore, immune responses following immunization were reduced in mice treated with SU5416. Findings of thymic atrophy and reduced weight gain during SU5416 treatment suggested elevated corticosterone levels. Indeed, a significant 5-fold increase in serum corticosterone was found 4 hours after treatment with SU5416. Importantly, adrenalectomy negated the effects of SU5416 treatment on primary immune tissues, and partial reversal of SU5416-induced changes was observed following blockade of glucocorticoid receptors. SU5416 has been reported to inhibit the activation of latent transforming growth factor (TGF)-β, a cytokine involved in the regulation of glucocorticoid release by the adrenal glands. Interestingly, treatment with a TGF-β receptor inhibitor, showed a similar phenotype as SU5416 treatment, including elevated serum corticosterone levels and thymic atrophy. Therefore, these results suggest that SU5416 induces glucocorticoid release directly from the adrenal glands, possibly by inhibition of TGF-β activation.

Inhibition of TGF-β signaling in mesenchymal stem cells of subchondral bone attenuates osteoarthritis

Osteoarthritis is a highly prevalent and debilitating joint disorder. There is no effective medical therapy for osteoarthritis due to limited understanding of osteoarthritis pathogenesis. We show that TGF–β1 is activated in the subchondral bone in response to altered mechanical loading in an anterior cruciate ligament transection (ACLT) osteoarthritis mouse model. TGF–β1 concentrations also increased in human osteoarthritis subchondral bone. High concentrations of TGF–β1 induced formation of nestin+ mesenchymal stem cell (MSC) clusters leading to aberrant bone formation accompanied by increased angiogenesis. Transgenic expression of active TGF–β1 in osteoblastic cells induced osteoarthritis. Inhibition of TGF–β activity in subchondral bone attenuated degeneration of osteoarthritis articular cartilage. Notably, knockout of the TGF–β type II receptor (TβRII) in nestin+ MSCs reduced development of osteoarthritis in ACLT mice. Thus, high concentrations of active TGF–β1 in the subchondral bone initiated the pathological changes of osteoarthritis, inhibition of which could be a potential therapeutic approach.

Abstract 340: MT1-MMP triggers an epithelial to mesenchymal transition program via activation of a TGF-β signaling pathway leading to Wnt5a induction

Abstract Metastases account for the vast majority of cancer-related deaths and is thought to involve a process known as epithelial-to-mesenchymal transition (EMT). EMT alters cells from a connected, stationary epithelial state to a more motile, invasive mesenchymal state. Expression of the Membrane-type 1 matrix metalloproteinase (MT1-MMP), one of the key mediators of tumor invasion and metastasis, has been reported to trigger prostate cancer cells to undergo EMT. We have found that MT1-MMP overexpression in LNCaP prostate cancer (LNCaP/MT1-MMP-GFP) and MCF-7 breast cancer (MCF-7/MT1-MMP) cells resulted in increased Wnt5a mRNA and protein. Conversely, MT1-MMP shRNA knockdown, in DU145 cells (DU145/MT1 shRNA) that express high endogenous MT1-MMP, decreased Wnt5a. Increased Wnt5a was required for MT1-MMP-mediated EMT; Wnt5a shRNA expression in MT1-MMP overexpressing cells reversed EMT, resulting in increased E-cadherin and a more epithelial morphology. Increased Wnt5a expression occured via MT1-MMP-mediated activation of a TGF-β signaling pathway. LNCaP/ MT1-MMP-GFP cells had enhanced levels of activated TGF-β, and DU145/MT1 shRNA cells displayed reduced levels of activated TGF-β relative to their respective control cells. Inhibition of TGF-β activity with a neutralizing antibody in LNCaP/MT1-MMP-GFP resulted in decreased Wnt5a expression relative to control cells. MT1-MMP-mediated TGF-β activation was inhibited with the MMP inhibitor BB3103, and LNCaP cells overexpressing the catalytically inactive MT1-MMP (LNCaP/MT1/E240-A) had almost undetectable levels of activated TGF-β. Both LNCaP/MT1-MMP-GFP treated with BB3101 and LNCaP/MT1/E-240-A failed to induce increased Wnt5a. These results support MT1-MMP catalytic activity as a requirement for activating TGF-β and for MT1-MMP mediated upregulation of Wnt5a. The CUTL1 transcription factor has been reported to be regulated by TGF-β signaling. LNCaP/MT1-MMP-GFP and MCF-7/MT1-MMP cells showed enhanced CUTL1 expression, and DU145/MT1 shRNA cells had decreased CUTL1 relative to control DU145/GFP shRNA. shRNA targeting of CUTL1, in LNCaP/MT1-MMP-GFP cells, resulted in decreased Wnt5a expression and reversal of the EMT phenotype. Upregulation of Wnt5a promoted anchorage-independent growth; Wnt5a shRNA knockdown in either LNCaP/MT1-MMP-GFP or in DU145 cells each resulted in markedly decreased growth in soft agar. Wnt5a shRNA expression in LNCaP/MT1-MMP-GFP also significantly decreased the growth of mouse tumors derived from these cells relative to tumors from LNCaP/MT1-MMP-GFP. These results demonstrate the significance of Wnt5a expression in MT1-MMP-mediated tumor progression. Collectively, these results highlight a novel link between MT1-MMP and the Wnt pathway, mediated by TGF-β signaling, that illuminate the relationship between these factors and their roles in EMT and metastasis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 340. doi:1538-7445.AM2012-340

Review of the activation of TGF-β in immunity

The evolutionarily conserved TGF-beta proteins are distributed ubiquitously throughout the body and have a role in almost every biological process. In immunity, TGF-beta has an important role in modulating immunity. Much is understood about the process of TGF-beta production as a latent molecule and of the consequences and the intercellular signaling of active TGF-beta binding to its receptors; however, there is little discussed between the production and activation of TGF-beta. This review focuses on what is understood about the biochemical and physiological processes of TGF-beta activation and identifies the gaps in understanding immune cell activation of TGF-beta. A mechanistic understanding of the process activating TGF-beta can lead to regulating multiple biological systems by enhancing or inhibiting TGF-beta activation.

Transforming growth factor-β in the brain regulates fat metabolism during endurance exercise

We have previously reported that the concentration of transforming growth factor-beta (TGF-beta) increases in the cerebrospinal fluid of rats during exercise and that there is an increase in whole body fat oxidation following the intracisternal administration of TGF-beta. These results led us to postulate that TGF-beta in the brain regulates the enhancement of fatty acid oxidation during exercise. To test this hypothesis, we carried out respiratory gas analysis during treadmill running following the inhibition of TGF-beta activity in rat brain by intracisternal administration of anti-TGF-beta antibody or SB-431542, an inhibitor of the type 1 TGF-beta receptor. We found that each reagent partially blocked the increase in the fatty acid oxidation. We also compared the plasma concentrations of energy substrates in the group administered anti-TGF-beta antibody and the control group during running. We found that the plasma concentrations of nonesterified fatty acids and ketone bodies in the group administered anti-TGF-beta antibody were lower than in the control group at the end of running. In the same way, we carried out respiratory gas analysis during treadmill running after depressing corticotropin-releasing factor activity in the brain using intracisternal administration of astressin, an inhibitor of the corticotropin-releasing factor receptor. However, there were no significant differences in respiratory exchange ratio or oxygen consumption in moderate running (60% maximum oxygen consumption). These results suggest that brain TGF-beta has a role in enhancing fatty acid oxidation during endurance exercise and that this regulation is executed at least partly via the type 1 TGF-beta receptor signal transduction system.

Glycosaminoglycans: use in treatment of diabetic nephropathy.

Glycosaminoglycans: use in treatment of diabetic nephropathy.

Stimulatory Effect of Lipoprotein (a) on Proliferation of Human Mesangial Cells: Role of Lipoprotein (a) in Renal Disease

As lipoprotein (a) [Lp(a)] abnormalities would accelerate glomerular injury, we studied the effect of Lp (a) on proliferation of cultured human mesangial cells (MC). Transfection of human apo (a) gene into human hepatoma cells, HepG2 cells, producing human apo B, resulted in the formation of Lp (a), while no Lp (a) was detected in control cells. In contrast, free apo (a) was detected in the medium of apo (a)-transfected MC. Incubation of cultured medium of HepG2 cells transfected with apo (a) gene with MC resulted in a significant increase in cell number compared to control (P<0.01). In contrast, little effect of transfection of apo (a) gene directly into MC on growth of MC was observed. Of importance, addition of LDL into the medium of MC transfected with apo (a) vector resulted in a significant increase in number of MC compared to control, whereas LDL did not show any effects on MC growth. As active TGF-β was not detected in the medium of MC, and addition of neutralizing anti-TGF-β antibody did not alter growth of MC, Lp (a) stimulated growth of MC via the independent mechanisms from the inhibition of TGF-β activation.