Latent Transforming Growth Factor Beta Research Articles

The Pathogenesis of Aortopathy in Marfan Syndrome and Related Diseases

Marfan syndrome is a systemic connective tissue disorder that is inherited in an autosomal-dominant pattern with variable penetrance. Although there are many clinical manifestations of this disease, the most life threatening are cardiovascular complications, including mitral valve prolapse and aortic root aneurysm. When the primary defect was discovered in the fibrillin-1 gene, it was hypothesized that mutations in fibrillin-1 resulted in a weakened and disordered elastic architecture. However, recent evidence has suggested that the Marfan syndrome is caused by more than just a disordered microfibril matrix. Interest was stimulated when it was discovered that fibrillin-1 mutations enhanced the release of sequestered latent transforming growth factor-beta, a well-described mediator of vascular remodeling. This article focuses on the pathophysiology of aortopathy in the Marfan syndrome and related diseases, with special emphasis on the role of transforming growth factor-beta in mediating the pathogenesis of this disease.

Modulating T cell functions does not alleviate chronic inflammatory skin lesions in K5.TGFβ1 transgenic mice

To use mice with chronic hyperproliferative skin inflammation as psoriasis models, their thorough phenotypic and functional characterization is indispensable. Mice with keratin 5 promoter-controlled overexpression of latent human Transforming Growth Factor (TGF)beta1 within the basal epidermis (K5.TGF beta 1 mice) show a psoriasiform phenotype, but the underlying pathogenic mechanisms are not entirely clear. To elucidate the contribution of T lymphocytes to the pathogenesis in K5.TGF beta 1 mice, we used three complementary approaches: first, peripheral T cells were eradicated via systemic treatment with CD3- or CD4-depleting antibodies. However, this elimination did not alleviate the chronic inflammatory disorder. Second, bone marrow transplantation from transgenic mice into wildtype recipients and vice versa resulted in the expected reconstitution of both adaptive and innate immune system but had little effect on the cutaneous phenotype both in wildtype and transgenic chimeras. Third, based on the hypothesis that the disease course could be modulated by regulatory T cells (Tregs), we expanded Tregs in vivo using a superagonistic anti-CD28 antibody. While this treatment achieved a threefold increase in Foxp3-expressing Tregs, there was little, if any, effect on the chronic skin inflammation. We conclude from our findings that T cells play little, if any, role in the skin lesions of K5.TGF beta 1 mice.

165. LOCATION OF ACTIVE TGFB1 IN THE MAMMARY GLAND DURING DIFFERENT STAGES OF DEVELOPMENT

Development of the mammary gland involves complex interactions between epithelial and stromal cells under the influence of hormones and cytokines. Transforming growth factor beta 1 (TGFB1) is a multi-functional cytokine that we have reported to be essential for normal mammary gland development. TGFB1 is produced and secreted as part of a latent complex, and requires activation at the site of action to have biological effects. In situ hybridisation studies have shown mRNA encoding Tgfb1 is mainly expressed by mammary epithelium; however, the expression pattern of active TGFB1 in the mammary gland during different developmental stages is still unclear. Mammary gland tissue was collected from mice at puberty (5 weeks old), adult diestrus and late pregnancy (day 18 pc). Frozen sections were stained with antibody specifically reactive with active TGFB1 protein (not latent TGFB1 or other TGFB isoforms) for immunofluorescent analysis. Qualitative assessment of the staining revealed different patterns of active TGFB1 localisation depending on developmental stage. The strongest expression of active TGFB1 was observed in the mammary gland at diestrus compared to puberty and pregnancy. At diestrus, active TGFB1 was located around the surface of mammary epithelial cells. The staining was heterogeneous, with distinct zones of active TGFB1 accumulated around some but not all epithelial cells. During puberty, active TGFB1 was observed only within the lumen of the ducts. During late pregnancy, TGFB1 was homogenously distributed within the alveolar epithelium. The different patterns of active TGFB1 observed during puberty, diestrus and pregnancy suggest that TGFB1 has different roles in the mammary gland dependent on developmental stage.

Transforming growth factor beta (TGFB) signaling is activated during porcine implantation: proposed role for latency-associated peptide interactions with integrins at the conceptus–maternal interface

The process of implantation is mediated by a complex network of signaling and adhesive factors. In the pig, latent and active transforming growth factor beta (TGFB), TGFB receptors (TGFBR), and integrins (ITGs) are present during the peri-implantation period. TGFB signals via TGFBR and activates downstream effector SMAD proteins 2 and 3 (p-SMAD2/3). Latency-associated peptide (LAP), part of the latent TGFB complex, is known to bind to ITG heterodimers and activate TGFB. We hypothesize that active TGFBs and TGFBRs along with LAP and ITGs functionally interact at the conceptus-maternal interface to mediate events essential for conceptus development and attachment in pigs. Uteri and conceptuses from days 10, 12, 16, 20, and 24 pregnant gilts were immunostained for TGFB, LAP, and ITG subunits (ITGAV, ITGB1, ITGB3, ITGB5, ITGB6, and ITGB8). Activation of TGFBRs was evaluated by the presence of phosphorylated downstream effector SMAD2/3. Binding of LAP to ITGs was also evaluated using porcine trophectoderm cells. Abundant active TGFB was detected at the apical surfaces of epithelia at the conceptus-maternal interface, and p-SMAD2/3 was detected at both conceptus attachment and nonattachment sites during implantation. Separate aggregates of LAP, ITGB1, ITGB5, and later ITGB3 were detected at the porcine conceptus-maternal interface, and binding of LAP to ITGs on apical surfaces was demonstrated. Results suggest that functional LAP-ITG adhesion complexes support conceptus attachment and promote TGFB activation leading to TGFB interaction with TGFBR supporting events of porcine implantation.

Intrauterine Infusion of Latency-Associated Peptide (LAP) During Early Porcine Pregnancy Affects Conceptus Elongation and Placental Size1

In the pig, transforming growth factor beta (TGFB), TGFB receptors (TGFBRs), and integrins are present during the peri-implantation period. Latency-associated peptide (LAP), a part of latent TGFB, can bind to integrin heterodimers via its Arg-Gly-Asp (RGD) sequence; therefore, ligand-receptor interactions between TGFB and TGFBRs, along with LAP and integrin heterodimers, may be functional in mediating events supporting conceptus elongation and attachment. With the use of surgically implantable osmotic pumps, we were able to maintain pregnancy with the aim of mechanistically altering in vivo receptor-ligand interactions involving TGFB with TGFBRs and LAP with integrins during porcine pregnancy. Day 9 pregnant gilts received intrauterine infusions of LAP-RGD, a recombinant mutant of LAP (LAP-RGE), or vehicle control and were ovariohysterectomized on Day 13 or 24 of pregnancy. We hypothesized that intrauterine infusion of LAP-RGD would decrease downstream signaling of TGFB while increasing LAP-integrin interactions and that net effect would enhance conceptus survival and attachment early in the peri-implantation period but possibly increase the chance of abnormal placentation later in pregnancy. Additionally, we hypothesized that infusion of LAP-RGE would disrupt TGFB signals but not alter integrin signaling, and thus the net result would be decreased conceptus survival and abnormal development. Unexpectedly, LAP-RGD intrauterine infusions resulted in a reduction of conceptus elongation, whereas infusions of LAP-RGE permitted implantation and placentation but resulted in larger fetal weight, allantois length, and allantoic fluid volume. Results suggest TGFB and integrins are contributing factors in the regulation of conceptus elongation and placental and fetal size.

Mutations in LTBP4 Cause a Syndrome of Impaired Pulmonary, Gastrointestinal, Genitourinary, Musculoskeletal, and Dermal Development

We report recessive mutations in the gene for the latent transforming growth factor-beta binding protein 4 (LTBP4) in four unrelated patients with a human syndrome disrupting pulmonary, gastrointestinal, urinary, musculoskeletal, craniofacial, and dermal development. All patients had severe respiratory distress, with cystic and atelectatic changes in the lungs complicated by tracheomalacia and diaphragmatic hernia. Three of the four patients died of respiratory failure. Cardiovascular lesions were mild, limited to pulmonary artery stenosis and patent foramen ovale. Gastrointestinal malformations included diverticulosis, enlargement, tortuosity, and stenosis at various levels of the intestinal tract. The urinary tract was affected by diverticulosis and hydronephrosis. Joint laxity and low muscle tone contributed to musculoskeletal problems compounded by postnatal growth delay. Craniofacial features included microretrognathia, flat midface, receding forehead, and wide fontanelles. All patients had cutis laxa. Four of the five identified LTBP4 mutations led to premature termination of translation and destabilization of the LTBP4 mRNA. Impaired synthesis and lack of deposition of LTBP4 into the extracellular matrix (ECM) caused increased transforming growth factor-beta (TGF-beta) activity in cultured fibroblasts and defective elastic fiber assembly in all tissues affected by the disease. These molecular defects were associated with blocked alveolarization and airway collapse in the lung. Our results show that coupling of TGF-beta signaling and ECM assembly is essential for proper development and is achieved in multiple human organ systems by multifunctional proteins such as LTBP4.

Sjögren’s Syndrome-Like Ocular Surface Disease in Thrombospondin-1 Deficient Mice

Thrombospondin-1 (TSP-1) is a major activator of latent transforming growth factor-beta in vitro as well as in vivo. Mice deficient in TSP-1, despite appearing normal at birth, develop a chronic form of ocular surface disease that is marked by increased apoptosis and deterioration in the lacrimal gland, associated dysfunction, and development of inflammatory infiltrates that result in abnormal tears. The increase in CD4(+) T cells in the inflammatory infiltrates of the lacrimal gland, and the presence of anti-Sjögren's syndrome antigen A and anti-Sjögren's syndrome antigen B antibodies in the serum resemble autoimmune Sjögren's syndrome. These mice develop an ocular surface disorder dry eye that includes disruption of the corneal epithelial layer, corneal edema, and a significant decline in conjuctival goblet cells. Externally, several mice develop dry crusty eyes that eventually close. The inflammatory CD4(+) T cells detected in the lacrimal gland, as well as those in the periphery of older TSP-1 null mice, secrete interleukin-17A, a cytokine associated with chronic inflammatory diseases. Antigen-presenting cells, derived from TSP-1 null, but not from wild-type mice, activate T cells to promote the Th17 response. Together, these results indicate that TSP-1 deficiency results in a spontaneous form of chronic dry eye and aberrant histopathology associated with Sjögren's syndrome.

Loss of function mutations in the gene encoding latent transforming growth factor beta binding protein 2, LTBP2, cause primary congenital glaucoma

Glaucoma is a heterogeneous group of optic neuropathies that manifests by optic nerve head cupping or degeneration of the optic nerve, resulting in a specific pattern of visual field loss. Glaucoma leads to blindness if left untreated, and is considered the second leading cause of blindness worldwide. The subgroup primary congenital glaucoma (PCG) is characterized by an anatomical defect in the trabecular meshwork, and age at onset in the neonatal or infantile period. It is the most severe form of glaucoma. CYP1B1 was the first gene genetically linked to PCG, and CYP1B1 mutations are the cause of disease in 20-100% of patients in different populations. Here, we report that LTBP2 encoding latent transforming growth factor beta binding protein 2 is a PCG causing gene, confirming results recently reported. A disease-associated locus on chromosome 14 was identified by performing whole genome autozygosity mapping in Iranian PCG families using high density single nucleotide polymorphism chips, and two disease-segregating loss of function mutations in LTBP2, p.Ser472fsX3 and p.Tyr1793fsX55, were observed in two families while sequencing candidate genes in the locus. The p.Tyr1793fsX55 mutation affects an amino acid close to the C-terminal of the encoded protein. Subsequently, LTBP2 expression was shown in human eyes, including the trabecular meshwork and ciliary processes that are thought to be relevant to the etiology of PCG.

Inhibition of latent transforming growth factor-β1 activation by lentivirus-mediated short hairpin RNA targeting the CD36 gene in NR8383 cells

CD36, a cell surface receptor for thrombospondin-1 (TSP-1), is believed to interact with latent transforming growth factor-beta1 (L-TGF-beta1) thereby activating its fibrogenic bioactivity. In this study, a lentiviral vector expressing a short hairpin RNA (shRNA) targeting the rat CD36 gene (Lv-shCD36) is developed and tested. To observe the inhibitory effect of Lv-shCD36 on the activation of L-TGF-beta1, a rat alveolar macrophage cell line (NR8383), infected with either Lv-shCD36 or Lv-shCD36-NC (non-silenced control lentivirus), was treated with 0.1 microg/ml bleomycin, which is known to stimulate alveolar macrophages to release increasing amounts of TGF-beta1. The results show that Lv-shCD36 can suppress expression of CD36 mRNA and protein in bleomycin-treated NR8383 cells. By quantifying active and total TGF-beta1 in the supernatant, it was discovered that the quantity of total TGF-beta1 is not significantly different between the three groups, while the quantity and percent of active TGF-beta1 in the Lv-shCD36 group was significantly lower than in either the bleomycin-treated group or the Lv-shCD36-NC group, respectively (P < 0.05). These results suggest that Lv-shCD36 can inhibit activation of L-TGF-beta1 secreted in bleomycin-treated NR8383 cells by decreasing the expression of CD36 on the cell membrane, thereby reducing binding of CD36 to TSP-1.

Structure and Interdomain Interactions of a Hybrid Domain: A Disulphide-Rich Module of the Fibrillin/LTBP Superfamily of Matrix Proteins

SummaryThe fibrillins and latent transforming growth factor-β binding proteins (LTBPs) form a superfamily of structurally-related proteins consisting of calcium-binding epidermal growth factor-like (cbEGF) domains interspersed with 8-cysteine-containing transforming growth factor β-binding protein-like (TB) and hybrid (hyb) domains. Fibrillins are the major components of the extracellular 10–12 nm diameter microfibrils, which mediate a variety of cell-matrix interactions. Here we present the crystal structure of a fibrillin-1 cbEGF9-hyb2-cbEGF10 fragment, solved to 1.8 Å resolution. The hybrid domain fold is similar, but not identical, to the TB domain fold seen in previous fibrillin-1 and LTBP-1 fragments. Pairwise interactions with neighboring cbEGF domains demonstrate extensive interfaces, with the hyb2-cbEGF10 interface dependent on Ca2+ binding. These observations provide accurate constraints for models of fibrillin organization within the 10–12 nm microfibrils and provide further molecular insights into how Ca2+ binding influences the intermolecular interactions and biomechanical properties of fibrillin-1.

Losartan Preserves Erectile Function After Bilateral Cavernous Nerve Injury via Antifibrotic Mechanisms in Male Rats

Angiotensin II is a known mediator of smooth muscle vasoconstriction and fibrosis. It up-regulates thrombospondin-1, a major activator of latent transforming growth factor-beta. Transforming growth factor-beta induces vascular fibrosis via intracellular SMAD signaling pathways. We evaluated the effect of treatment with the angiotensin II type 1 receptor antagonist losartan on erectile function in the rat following bilateral cavernous nerve injury. A total of 36 adult male rats were divided equally into 6 groups, including group 1-sham surgery with cavernous nerve exposure only plus vehicle, group 2-sham surgery plus oral low dose losartan (10 mg/kg per day), group 3-sham surgery plus high dose losartan (40 mg/kg per day), group 4-bilateral cavernous nerve injury (3-minute crush using a hemostat clamp) plus vehicle, group 5-bilateral cavernous nerve injury plus low dose losartan and group 6-bilateral cavernous nerve injury plus high dose losartan. Seven days following surgery erectile function was measured by electrically stimulating the cavernous nerves and monitoring intracavernous pressure. Penile tissue was collected for Western blot analysis of fibronectin, transforming growth factor-beta, thrombospondin-1, alpha-actin, and phosphorylated and total SMAD2 and SMAD3 expression. Erectile function was significantly decreased after bilateral cavernous nerve injury compared with that after sham surgery (p <0.01). Low and high dose losartan preserved erectile function after bilateral cavernous nerve injury compared to that in vehicle controls (p <0.01 and <0.05, respectively). Fibronectin, pSMAD2, pSMAD3, transforming growth factor-beta-1, thrombospondin-1 and alpha-actin expression was up-regulated, and total SMAD2 and SMAD3 expression was down-regulated in the penis after bilateral cavernous nerve injury. Each dose of losartan after bilateral cavernous nerve injury significantly attenuated the up-regulated expression of fibronectin (p <0.01), pSMAD2 (p <0.05) and thrombospondin-1 (p <0.05), and up-regulated total SMAD2 (p <0.05). These data suggest that fibrotic activators in the penis may cause decreased erectile function after bilateral cavernous nerve injury. Angiotensin II type 1 receptor antagonism may counteract this effect and promote erectile function preservation for conditions associated with penile fibrosis.

Thymus cell antigen‐1‐expressing cells in the oval cell compartment†

Thymus cell antigen-1 (Thy-1)-expressing cells proliferate in the liver during oval cell (OC)-mediated liver regeneration. We characterized these cells in normal liver, in carbon tetrachloride-injured liver, and in several models of OC activation. The gene expression analyses were performed using reverse-transcriptase polymerase chain reaction (RT-PCR), quantitative RT-PCR (Q-RT-PCR) of cells isolated by fluorescence-activated cell sorting (FACS), and by immunofluorescent microscopy of tissue sections and isolated cells. In normal liver, Thy-1(+) cells are a heterogeneous population: those located in the periportal region do not coexpress desmin or alpha smooth muscle actin (alpha-SMA). The majority of Thy-1(+) cells located at the lobular interface and in the parenchyma coexpress desmin but not alpha-SMA, i.e., they are not resident myofibroblasts. Although Thy-1(+) cells proliferate moderately after carbon tetrachloride injury, in all models of OC-mediated liver regeneration they proliferate quickly and expand significantly and disappear from the liver when the OC response subsides. Activated Thy-1(+) cells do not express OC genes but they express genes known to be expressed in mesenchymal stem cells (CD105, CD73, CD29), genes considered specific for activated stellate cells (desmin, collagen I-a2, Mmp2, Mmp14) and myofibroblasts (alpha-SMA, fibulin-2), as well as growth factors and cytokines (Hgf, Tweak, IL-1b, IL-6, IL-15) that can affect OC growth. Activated in vitro stellate cells do not express Thy-1. Subcloning of Thy-1(+) cells from OC-activated livers yield Thy-1(+) fibroblastic cells and a population of E-cadherin(+) mesenchymal cells that gradually discontinue expression of Thy-1 and begin to express cytokeratins. However, upon transplantation these cells do not differentiate into hepatocytes or cholangiocytes. Activated Thy-1(+) cells produce predominantly latent transforming growth factor beta. Thy-1(+) cells in the OC niche are activated mesenchymal-epithelial cells that are distinct from resident stellate cells, myofibroblasts, and oval cells.

Lysophosphatidic Acid Induces αvβ6 Integrin-Mediated TGF-β Activation via the LPA2 Receptor and the Small G Protein Gα q

Activation of latent transforming growth factor beta (TGF-beta) by alphavbeta6 integrin is critical in the pathogenesis of lung injury and fibrosis. We have previously demonstrated that the stimulation of protease activated receptor 1 promotes alphavbeta6 integrin-mediated TGF-beta activation via RhoA, which is known to modulate cell contraction. However, whether other G protein-coupled receptors can also induce alphavbeta6 integrin-mediated TGF-beta activation is unknown; in addition, the alphavbeta6 integrin signaling pathway has not yet been fully characterized. In this study, we show that lysophosphatidic acid (LPA) induces alphavbeta6-mediated TGF-beta activation in human epithelial cells via both RhoA and Rho kinase. Furthermore, we demonstrate that LPA-induced alphavbeta6 integrin-mediated TGF-beta activity is mediated via the LPA2 receptor, which signals via G alpha(q). Finally, we show that the expression levels of both the LPA2 receptor and alphavbeta6 integrin are up-regulated and are spatially and temporally associated following bleomycin-induced lung injury. Furthermore, both the LPA2 receptor and alphavbeta6 integrin are up-regulated in the overlying epithelial areas of fibrosis in patients with usual interstitial pneumonia. These studies demonstrate that LPA induces alphavbeta6 integrin-mediated TGF-beta activation in epithelial cells via LPA2, G alpha(q), RhoA, and Rho kinase, and that this pathway might be clinically relevant to the development of lung injury and fibrosis.

Latent Transforming Growth Factor-β-Binding Protein-4 Regulates Transforming Growth Factor-β1 Bioavailability for Activation by Fibrogenic Lung Fibroblasts in Response to Bleomycin

Recent evidence suggests that subsets of lung fibroblasts differentially contribute to fibrogenic progression. We have previously shown that a subset of rat lung fibroblasts with fibrogenic characteristics [Thy-1 (-) fibroblasts] responds to stimuli (bleomycin, interleukin-4, etc) with increased latent transforming growth factor (TGF)-beta activation, whereas non-fibrogenic Thy-1-expressing [Thy-1 (+)] fibroblasts do not. Activation of latent TGF-beta1 by interstitial lung fibroblasts is critical for fibrogenic responses. To better understand the susceptibility of fibrogenic fibroblasts to the stimulation of TGF-beta activation, we examined the role of latent TGF-beta-binding proteins (LTBPs), key regulators of TGF-beta bioavailability and activation, in TGF-beta1 activation by these fibroblasts. Treatment of fibroblasts with bleomycin up-regulated LTBP-4 mRNA, protein, and soluble LTBP-4-bound large latent TGF-beta1 complexes in Thy-1 (-) fibroblasts to significantly higher levels than in Thy-1 (+) fibroblasts. Bleomycin-induced TGF-beta1 activation required LTBP-4, since lung fibroblasts deficient in LTBP-4 did not activate TGF-beta1. Expression of LTBP-4 restored TGF-beta1 activation in response to bleomycin, but expression either of LTBP-4 lacking the TGF-beta-binding site or only the TGF-beta-binding domain did not. Bleomycin treatment of mice increased LTBP-4 expression in the lung. Thy-1 knockout mice had increased levels of both LTBP-4 expression and TGF-beta activation, as well as enhanced Smad3 phosphorylation compared with wild-type mice. Together, these data identify a critical role for LTBP-4 in the regulation of latent TGF-beta1 activation in bleomycin-induced lung fibrosis.

Augmentation of Murine Vasculogenesis by Injected Human Hematopoietic Stem Cells in Response to Ischemia Follows Early Activation of Innate Immune Response

Although NOD.SCID mice lack an adaptive immune response, their innate immune system is intact. NOD.SCID mice are the model system used for both allo- and xeno-graft cell therapies to in vivo neovascularization of ischemic beds. As most previous studies have used undefined or mixed cell population, we tested the hypothesis that selected human umbilical cord blood (UCB) CD133+ stem cells (human HSC) would promote in vivo neovascularization, thereby conferring a therapeutic advantage over the mixed cell population found in mononuclear cell (MNC) preparations. These experiments focused on the murine response within the ischemic bed to human HSC cells as evaluated by gene array analyses. Gene array data was mined for inflammation, innate immunity and wound repair genes, with a focus on factors favorable to regeneration, angiogenesis and limits collagen deposition (scar formation). Normal mammalian wound repair occurs in 3 overlapping stages inflammation, new tissue formation, and remodeling. To evaluate these cell populations, NOD.SCID mice underwent femoral ligation and were divided into 3 study groups: controls (media alone), human selected UCB CD133+ HSC, or human non-selected UCB MNC. Previously, laser Doppler studies after femoral ligation showed significantly improved blood flow ratio in animals treated with human HSC vs. controls, 0.55±0.06 (n=9) and 0.37±0.03 (n=12, p<0.05), respectfully, and histology confirmed increased capillary density in animals treated with human HSC compared to controls, (320±18 and 131±6.9 cells/mm2; respectively p<0.0001). To compare the treatment effects on the early transcriptome and to wound repair, murine gene expression microarrays (Affymetrix murine GeneChip 430 2.0) of RNA extracted from tissues harvested from the ischemic limbs 3 days following femoral ligation and injection of cells (n=3 each experimental group) were utilized. In comparing control mice to those receiving human selected CD133+ HSC, 414 genes with 2-fold or greater change was observed. Several genes were differentially regulated between study groups. The level of IL12a mRNA was 2-fold lower in the hindlimb tissue of mice treated with CD133+ HSC than in the untreated controls: IL12 is a known regulator of the TH1-associated cytokine INF-g and TNF-a, a primary regulator of immune cells and cytolytic stimuli. While there was no observed change in the levels of INF-g in the hindlimb, 17 interferon induced genes were observed to be significantly lower in the human HSC-treated hindlimb compared to controls. Genes induced by TGF-b were lower including IL-12a, Ras-related genes, and the inhibitor latent transforming growth factor beta binding protein 2 was 3-fold higher in the hindlimbs treated with CD133+ HSC cells compared to controls. Innate immune cytokine receptors IL4 and IL13 mRNAs were expressed at a lower level than that seen in control mice. However, the IL6 receptor increased 3-fold in the human selected CD133+ HSC-treated cells as well as the downstream genes TIMP-1 (tissue inhibitor of matrix metalloprotease) and Pim1 gene, a stressed induced serine-threonine kinase which promotes cell survival. These results confirm prior observations in IL-6−/− knockout mice demonstrating delayed responses in leukocyte infiltration, angiogenesis and tissue remodeling. In addition, there was significant increases in genes regulated by the Wnt signaling pathway, compared to hindlimbs treated with UCB MNC cells including: Jun (2-fold higher), Sox4 (2–5 fold higher), Frizzle homolog 8 (2-fold), and MAPKKK4 (2-fold higher). The modulation of these factors and the observation that the inhibitor of Wnt signaling dickkopf was reduced 2.3-fold may indicate enhanced regenerative mechanisms as Wnt functions during embryogenesis and also during adult limb formation during metamorphosis. In summary, NOD.SCID treated with human selected CD133+ HSC after femoral ligation demonstrate significantly improved capillary density and blood flow recovery at later time points (day 28–42). Receptors and cytokines regulating innate immunity are significantly higher at an early time point (day 3) in mice treated with human CD133+ HSC suggesting an important regulatory role for innate inflammatory responses contributing to augmentation of vasculogenesis after acute vascular injury.

Insulin-Like Growth Factor-II Is Increased in Systemic Sclerosis-Associated Pulmonary Fibrosis and Contributes to the Fibrotic Process via Jun N-Terminal Kinase- and Phosphatidylinositol-3 Kinase-Dependent Pathways

Systemic sclerosis (SSc)-related pulmonary fibrosis, for which there are few effective therapies, is the most common cause of SSc-related mortality. We examined insulin-like growth factor (IGF)-II expression in explanted lung tissues from control and SSc patients to determine its role in the pathogenesis of fibrosis. IGF-II levels in vivo were detected using immunohistochemistry. Primary lung fibroblasts were cultured from lung tissues, and IGF-II mRNA was measured using reverse transcriptase-polymerase chain reaction. Western blot analysis measured extracellular matrix (ECM) production and phosphorylated signaling molecules. Immunostaining revealed increased IGF-II expression in fibroblastic foci of SSc lungs. Furthermore, primary SSc lung fibroblasts had a fourfold increase in IGF-II mRNA and a twofold increase in IGF-II protein compared with normal lung fibroblasts. IGF-II mRNA in SSc lung fibroblasts was expressed primarily from the P3 promoter of the IGF-II gene, and IGF-II induced both a dose- and time-dependent increase in collagen type I and fibronectin production. IGF-II triggered the activation of both phosphatidylinositol-3 kinase and Jun N-terminal kinase signaling cascades, the inhibition of which diminished IGF-II-induced ECM production. Our study demonstrates increased local IGF-II expression in SSc-associated pulmonary fibrosis both in vitro and in vivo as well as IGF-II-induced ECM production through both phosphatidylinositol-3 kinase- and Jun N-terminal kinase-dependent pathways. Our results provide novel insights into the role of IGF-II in the pathogenesis of SSc-associated pulmonary fibrosis.

Expression of latent transforming growth factor beta binding proteins in the rat brain

Transforming growth factor-betas are expressed in the brain, have neuroprotective functions, and may be involved in the pathogenesis of neurodegenerative disorders. Their intracellular processing, secretion, and extracellular activation requires latent transforming growth factor-beta binding proteins (LTBPs) as demonstrated in peripheral organs. Here, we first report that the four types of LTBPs are expressed in the rat brain based on reverse-transcriptase polymerase chain reaction (RT-PCR) and that the subtypes have different topographical distributions based on in situ hybridization histochemistry. LTBP-1 has a high expression level in several brain regions including choroid plexus, cerebral cortex, medial amygdaloid nucleus, anteromedial and midline thalamic nuclei, medial preoptic area, arcuate and dorsomedial hypothalamic nuclei, superior olive, and area postrema. LTBP-3 and -4 are the most widely distributed LTBPs. Both are abundant in the cerebral cortex, cerebellum, hypothalamus, amygdala, brainstem motor nuclei, and area postrema. In addition, LTBP-3 mRNA is also abundant in the choroid plexus, globus pallidus, anterior and reticular thalamic nuclei, mamillary body, substantia nigra, red nucleus, pontine nuclei, some brainstem sensory nuclei, and reticular formation, while LTBP-4 is more abundant in the hippocampus and the parabrachial nuclei. In contrast, the expression of LTBP-2 is restricted to cerebral cortex, CA1 neurons of the hippocampus, and perifornical/lateral hypothalamic areas. The hypothalamic cells were identified by double in situ hybridization histochemistry as orexin-synthesizing neurons, demonstrating that LTBP expression can be very specifically regulated. Our data demonstrate that each type of LTBPs have highly distinct distributional patterns suggesting that the expression of LTBPs are specifically regulated in the brain.

The absence of latent transforming growth factor-beta binding protein–1 (LTBP–1) inhibits TGF-beta secretion

The absence of latent transforming growth factor-beta binding protein–1 (LTBP–1) inhibits TGF-beta secretion

Can matrix metalloproteinases be targeted in hepatic ischemia/reperfusion injury?

Can matrix metalloproteinases be targeted in hepatic ischemia/reperfusion injury?

Latent transforming growth factor binding protein 4 (LTBP‐4) is downregulated in human mammary adenocarcinomas in vitro and in vivo

Transforming growth factor beta (TGF-ss) is able to inhibit proliferation of epithelial cells and is involved in the carcinogenesis of human mammary tumours. Three latent transforming growth factor-beta binding proteins (LTBP-1, -3 and -4) are involved in TGF-beta function. The aim of the study was to analyze the expression profiles of TGF-beta 1 and 2 and LTBP-4 in human mammary carcinoma cell lines as well as in human mammary tumours. Expression analysis was performed at the transcription and protein level under in vivo and in vitro conditions. LTBP-4 expression was quantitatively analysed in human carcinomas of the mammary gland and in healthy mammary tissues of the same patients. Downregulation of LTBP-4 in all investigated human mammary tumours compared to normal tissues could be demonstrated. Results also revealed that protein levels of TGF-beta 1 are downregulated and of TGF-beta 2 are upregulated in human mammary carcinoma cell lines compared to primary (normal) human mammary epithelial cells. LTBP-4 reduction in neoplasms leads to a possible decrease of TGF-beta 1 extracellular deposition with reduced TGF-beta 1 bioavailability. TGF-beta 2 was upregulated, which indicates a possible compensatory mechanism. This study demonstrated a possible functional role of LTBP-4 for TGF-beta bioavailability with respect to carcinogenesis of human mammary tumours in vivo and in vitro.